Virtual Reality: The future of NASA

pg. 10

Miracle Cancer Drug

Princeton professor’s miracle drug

is considered the most

effective treatment

for cancer.

Malaria-ResistantMosquitos Looking towards a

future free of malaria.

VOL. 8 NO. 2 SPRING 2007

INNO ATION The Princeton Journal of Science and Technology

VOL. 8 NO. 2 SPRING 2006

TE

CH

NO

LOG

YControlled growth of E. coli provide breakthroughs in the study of

the mechanisms governing evolution.

A breed of mosquitos has been genetically engineered to be im-

mune to malaria, pointing to a possible eradication of the disease..

Did you think that virtual reality, vertical take-off, and landing

vehicles were in the realm of science fi ction? Think again. A

NASA chief scientist discusses future technologies of NASA

and its space program.

Working together: An interdisciplinary group of Princeton profes-

sors collaborate to decode fMRI brain images.

Dr. Edward C. Taylor of Princ-

eton University has developed

what is hailed as the most suc-

cessful cancer drug in history:

Alimta.

A step-by-step analysis of what really goes on in drug creation and evolution.

Screening for inhibitors of protein aggregation may halt the

onset of Alzheimer’s Disease.

Bacteria as a Model for Evolution

4

6

Malaria-Resistant Mosquitos

The Future of NASA

14Redesigning the Hydrogen Fuel Cell

ME

DIC

INE

18

From Laboratory to Patient

Halting the Onset of Alzheimer’s

Taylor’s Miracle Cancer Drug

20

26

10

INNO ATION

23

APCase8Jennifer Hsiao shares her experience studying the feedback regu-

lation of APCase.

Crossword Challenge 17

6

BIO

LOG

Y

Structural analysis of the cell reveals that the mechanisms regulat-

ing p53 degradation can help in the treatment of cancer.

p53 for Treating Cancer

6

10

Editor-in-ChiefSarah Weinstein

Assistant Editor-in-ChiefDavid Tao

Business AdministrationKenton Murray

WritersLajhem Cambridge

Jill FefferJennifer HsiaoKevin KungBrian LeVeeJessica Lucas

David TaoSarah WeinsteinJosephine Wolff

EditorsLajhem Cambridge

Kevin KungMegan Murray

Anupama PattabiramanAngela Wu

Andrew YangKeren Zhou

Layout TeamHead Alyce Tzue

Janice ChouJill Feffer

Elizabeth Szamreta

LETTER FROM THE EDITOR OUR STAFF

This issue of Innovation is your window into the exciting world of medical research. Highlights include glimpses into can-cer research, a genetically engineered cure for malaria, chem-istry’s approach to Alzheimer’s disease, and the clinical stud-ies supporting drug development. Enriching the issue’s vast swathe of medically oriented articles are excursions into evo-lutionary science, chemical engineering, and NASA’s ongoing conquest of space and search for the technology of tomorrow.

Innovation’s mission has always been twofold – we aim to deliver a microcosm of the momentous science research con-ducted here at Princeton while granting students access to the eminent professors and researchers on campus, thereby forg-ing a rapport between the present and future generations of scientists and discoverers. In other words, dear readers, we seek to bring the sciences to your doorstep, and at the same time, send you out into the vast world of scientiÞ c innovation.

Our journal was made possible by the hard work and dedication of our Innovation team coupled with the generous support of the University and in particular the School for Engineering and Applied Sciences. We would also like to thank the professors and research-ers who so generously offered their time for the ediÞ cation of the Princeton community. And Þ nally, we wish to extend our gratitude to you, dear reader, for your continued support and enthusiasm.

Ad Astra Per Scientiam, Sarah Weinstein, Editor-in-Chief

Please contact us with your advice, questions, and thoughts at slweinst@princeton.edu or innov@princeton.edu. We would love to hear from you.

Many thanks to our contributors, without whom Innovation would not have been possible:

The Departments of Chemical Engineering, Computer Science, Geosciences, and Mo-lecular Biology, the Council of Science and Technology, Pharmanet, and The School of Engineering and Applied Sciences.

Dear Readers,

Cover image courtesy of cs4n.org.

2

INNO ATION

THE INNOVATION SOCIETY is dedicated to bringing scientiÞ ctopics into the mainstream of campus discussion. We areexcited to be able to bring cutting-edge science research to

your doors, but we can’t do it without your support.

For more information contact Sarah Weinsteinat slweinst@princeton.edu or innov@princeton.edu

INNOVATION MAGAZINE

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Structural Analysis Reveals

Interactions Regulating p53

Degradation and Offers Insights

into Cancer Therapeutics

Recent research discoveries

made by structural biologist

Yigong Shi and fellow research-

ers lend insight into the molecular

mechanisms controlling the cell cy-

cle. The life cycle of a cell, includ-

ing growth, division, and death,

is a tightly regulated process that

depends upon the complex, coor-

dinated interactions of numerous

molecules. Abnormalities in cell

cycle control often cause cells to

experience an increase in growth,

a decrease in death, or proliferation

at inappropriate times, all of which

contribute to tumorigenesis and the

onset of cancer. Greater knowledge

of how certain molecules function to

regulate the cell cycle or induce cell

death facilitate both an understand-

ing of how cancer develops and

how to generate targeted therapies

that may help to treat the disease.

One such class of regulatory pro-

teins, known as tumor suppressors,

functions to negatively regulate the

cell cycle and inhibit cell growth.

Thus, abnormal levels of these pro-

teins, along with mutations in the

genes that encode them, are fre-

quently implicated in cancer. In fact,

the most frequently mutated gene in

all cancers involves one particular

tumor suppressor protein p53, which

weighs 53 kDa and is 393 amino

acids long. When cells experience

stress or DNA damage, p53 accu-

mulates and responds with a number

of anti-cancer mechanisms. First, it

may activate genes that encode for

proteins that are responsible for

repairing damaged DNA. Second,

p53 may arrest the cell cycle by up-

regulating cyclin dependent kinase

inhibitors that prevent the transi-

tion from G1 into S phase. Lastly,

upon irreparable DNA damage, p53

can initiate apoptosis, or cell death.

Though 50% of cancers char-

acterized by p53 abnormalities in-

volve TP53 mutations that produce

dysfunctional p53 protein, the other

half of the time patients have a wild-

type p53 gene whose product faces

accelerated degradation. In normal,

unstressed cells, p53 is kept at low

levels by constant degradation me-

diated by another protein, MDM2.

MDM2 is a ubiquitin ligase that spe-

cifi cally tags p53 for degradation by

adding ubiquitin groups and facili-

tating its transport from the nucleus,

Abnormalities in cell cy-cle control often cause cells to experience pro-liferation at inappropri-ate times, contributing to tumorigenesis and the onset of cancer.

// BY JESSICA LUCAS

The diagram shows the progression

of p53 mutation caused by overex-

pression of its inhibitor, the MDM2

oncogene.

4

where it acts a transcription factor, to

proteasomes in the cytosol. Accord-

ingly, higher levels of MDM2 result

in lower levels of p53. Interactions

between p53 and MDM2 can be in-

hibited by the activity of kinases,

whose phosphorylation of p53 in-

duces a conformational change that

blocks MDM2 binding and instead

activates the protein to transcribe

genes involved in cell damage re-

pair, arrest, or death. Thus, control-

ling the cell cycle by interfering at

a number of places in the p53 path-

way offer potential mechanisms

to ameliorate the cell cycle abnor-

malities associated with cancer.

One such approach would involve

the down-regulation of MDM2 to

block p53 degradation and thus up-

regulate its levels. This should help

to achieve normal rates of cell pro-

liferation and death in cancer cells.

Insights into achieving this end

became possible several years ago

with the discovery of HAUSP, an

enzyme that functions

to deubiquitylate,

or remove ubiqutin

from, a target protein

to prevent its degra-

dation. Though ini-

tially discovered as a

p53 directing protein,

it actually was redis-

covered as an essen-

tial protein for MDM2

stability, inhibiting its

self-degradation ac-

tivity through deubiq-

uitylation. Although

p53 and MDM2 bind

HAUSP in a mutu-

ally exclusive manner,

Shi’s team discovered

that MDM2 binds to

HAUSP with a greater

affi nity than p53. They suggest that

perhaps MDM2’s conformation af-

fords more extensive opportunities

for association with HAUSP than

does p53. To obtain insights into

function, Shi and his colleagues

used crystallography to determine

the structure of HAUSP’s catalytic

domain. They discovered that sub-

strates bind to a groove in a section

called the TRAF (Tumor Recep-

tor Associating Factor) domain at

the N-terminus of HAUSP via a

small peptide of fi ve to six amino

acids. They were able to elucidate

the oligopeptide sequence by gen-

erating mutations in amino acid

residues at the substrates’ bind-

ing sites and observing the effects.

The researchers reason that inter-

fering with HAUSP function antago-

nizes cells’ ability to deubiquitylate

MDM2. If MDM2 remains tagged

for degradation, its levels will de-

crease. Without functional ubiquit-

ing ligase to target p53 for degrada-

tion, the protein’s levels will rise.

The therapeutic approach involves

designing small inorganic or pep-

tide-like molecules, which simulate

the MDM 2 moeity that binds to

the TRAF domain of HAUSP. This

“peptidomimetic” molecule would

thus act as a competitive inhibitor

by associating with HAUSP in such

a way that prevents it from interact-

ing with MDM2. As a result, MDM2

will remain ubiquitylated and it will

be degraded, boosting the amount of

p53 to levels that will slow growth

and induce apoptosis of tumor

cells. Shi looks enthusiastically

toward collaboration with venture

capitalist fi rms to synthesize such

compounds. Once a few lead mol-

ecules have been produced, phar-

macokinetic analysis of their ef-

fect on restoring p53 can be tested

in cells that over express MDM2.

Ribbon drawing of the p53 core domain-DNA

complex showing the six most frequently mutated

residues of p53. The side chains of these residues

are colored yellow, the core domain is light blue,

and the DNA is dark blue. The zinc atom is shown

as a red sphere.

Thus, controlling the cell cycle by interfering at a number of places in the p53 ameliorates the cell cycle abnor-malities associated

with cancer.

I’m a junior in the MOL de-

partments pursuing a WWS

certifi cate, and I’m from

Pearl River, NY, a suburb

outside NYC. I’m interested in

a career in oncology clinical

research.

5

// BY LAJHEM CAMBRIDGE

In year and a half, these scien-

tists have created a mini ecosystem

played out on silicon. Escherichia

coli, a bacterium commonly found

in the intestines of humans and other

animals, has commonly been used in

laboratories and is well researched.

In this model, a silicon structure

which provides compartments that

contain different levels of resourc-

es houses the E. coli. The bacteria

must then adapt to the different en-

vironments in order to survive. The

scientists track the E. coli and ob-

serve how these factors affect the

population growth. They are able to

monitor and tweak the different en-

vironments in which the E. coli live.

Initially, Keymer and his col-

leagues were unsure if their experi-

mental bacteria would behave in the

same manner

as they would

under normal

c o n d i t i o n s

given that the

E. coli might

interact differ-

ently in a con-

fi ned space.

Yet using such

a small scale to model real world

complexities can be quite useful,

especially in this case. First, it is

important to consider that human

cells are approximately the same

size as the E. coli bacteria, and that

even the most complex biological

systems are entirely

dependent upon the

interaction between

cells. Moreover,

just as in natural

environments, the

bacteria fi nd nich-

es, or “pockets of

opportunity,” ac-

cording to Key-

mer, responding to abundant re-

sources or competition. The E.

coli bacteria interact in the same

In order to understand the com-plexities of the real world, sci-

entists often refer to models. In this same manner, a team made up of Princeton scientists, including Juan Keymer, PeterGalajda and Robert Austin – all membersof the Physics Department, with strongbackgrounds in Biology – have comeup with a way to model evolution.

b a c t e r i a

provide modelfor

EVOLUT ION

By simply rewarding bacteria with food orpunishing them with a laser, scientists can create the bacterial cells they prefer.

6

way, fi nding niches and adapting

and evolving to fi nd and fi ll them.

The research being done is heav-

ily based in both theoretical and

evolutionary biology. Darwin is

most famous for putting forth his

theory of evolution in On the Origin

of Species. This theory states that

by natural selection those organisms

better adapted to an environment

will produce offspring that have in-

herited the genes that enabled the

parents to survive. This process can

then lead to a new species. In this

experiment, however, it is diffi cult

to say defi nitively whether or not the

E. coli bacteria have evolved, since

drawing the line between species is

more diffi cult for single-celled or-

ganisms. Furthermore, the common

defi nition of a species requires the

organisms to inter-

breed and produce

fertile offspring,

but bacteria such

as E.coli asexu-

ally reproduce,

thus quickly ren-

dering this defi -

nition inapplicable. The team of

scientists, however, has been able

to obtain cells that have adapted

to and survived the environments

in which they have been placed,

and thus, they have been able to

observe the process of speciation

and evolution from the beginning.

Moreover, despite initial concerns,

the bacteria are successfully pro-

viding a great experimental eco-

system that is helping scientists to

understand the natural environment.

Another novel development born

of this research has several interest-

ing implications. Instead of working

from the inside of the bacterial cells,

for example, using

plasmids to alter

the cell’s DNA or

using macrophages

as a microbiologist

would, these scien-

tists need only to

alter the environ-

ment to effect the

desired changes.

With this nanotech-

nology, the scien-

tists can essentially

engineer cells. Just

through what is

understood about

natural selection, they

can select for bacteria that produce

a certain byproduct. By simply “re-

warding” the bacteria with food or

space, or by “punishing” them with

light from a laser,

scientists can choose

and create the bacte-

rial cells they prefer.

In theory, the sci-

entists can make a

whole structure, on

a bigger scale, with

compartments full of bacteria cre-

ating different products. This in-

frastructure can become a cheaper

or more effi cient alternative in re-

source production. What normally

would require money, many trials,

and space, can be simplifi ed and

streamlined. For example, in one

compartment scientists can select for

bacteria that produce hydrogen and

another, oxygen; alter the niche and

alter the cells. It’s as simple as that.

The industrial applications of

this technology are bound only by

the imagination. For instance, giv-

en this technology, cumbersome

oxygen tanks could theoretically

be replaced by inexhaustible appa-

ratuses, as long as food is provided

for the bacteria. According to Key-

mer, another outcome is the possi-

bility of adding “bio-functionality”

to certain materials, such as silicon

or metal alloys, so that the materi-

als gain organic function. Similarly,

the medicinal uses may become ir-

replaceable, as the bacteria struc-

ture could be used in transplants,

perhaps to consume an unwanted

toxin or provided any number of

life saving substances. Although the

realization of such applications will

require a great deal of research and

time, the merge of nanotechnology

and biology in this project to create

these “bacteria machines” is com-

pletely innovative and surely will

lead to advances in many industries.

A fl orescently labeled sample of E. coli bacteria.

The industrialapplications of

this technology are bound only by

the imagination.

Lajhem is a freshman who

plans on majoring in molecular

biology with a pre-med focus.

She is very involved in biology

research and has spent the last

two summers in a biology lab at

Rider University. She has lived in

New Jersey for most of her life.

7

// BY JENNIFER HSIAO

An important metabolic path-

way for organisms is de novo

(i.e. synthesis from smaller molecu-

lar precursors with lower molecular

weight) pyrimidine biosynthesis.

Pyrimidine nucleotides include uri-

dine, cytidine, and thymidine phos-

phates and they are needed for DNA

replication and RNA synthesis, pro-

cesses which are important for all

organisms. In the fi rst step towards

pyrimidine biosynthesis, an enzyme

called aspartate transcarbamylase

(ATCase) catalyzes the conversion of

reactants L-aspartate and carbamoyl

phosphate to carbamoyl aspartate.

ATCase is a model enzyme for

studying allosteric regulation. Allo-

steric comes from the Greek words

allos, meaning “other,” and stereos,

meaning “shape.” Therefore, allo-

steric regulation refers to the control

of enzyme activity through binding

of an effector molecule to a site other

than its active site (i.e. an allosteric

site). The allosteric binding causes a

conformational change in the struc-

ture of the enzyme. This can either

inhibit or enhance the activity of the

enzyme. Another common example

of an allosterically regulated protein

is hemoglobin, which carries oxygen

within a red blood cell. The binding

of oxygen to hemoglobin causes a

conformational change in hemoglo-

bin such that the affi nity for oxy-

gen of its active sites is increased.

ATCase is comprised of two dif-

ferent subunits; the larger subunit

is the catalytic (c) subunit, while

the smaller one is the regulatory (r)

subunit. The regulatory subunit has

no catalytic activity. The catalytic

subunit binds the substrates (both

reactants, L-aspartate and carbamyl

phosphate), while the regulatory

subunit can bind NTPs (N=A, C,

G, or U), and is responsible for the

allosteric aspects of ATCase. Wang

et al. have experimentally observed

ordered substrate binding, whereby

carbamoyl phosphate binds fi rst,

causing an induced-fi t conforma-

tional change. This transformation

alters the electrostatics of ATCase’s

active site, thus establishing a suit-

able binding site for L-aspartate.

The binding of L-aspartate triggers

a second induced fi t conformational

change, the “domain closure,” which

not only causes a quaternary confor-

mational change, but more impor-

tantly facilitates the catalytic reac-

tion (Wang 2005). CTP and UTP are

inhibitors, and ATP is an activator;

these have all been shown to bind to

the regulatory (r) subunits (Bethell

1968). According to Bethell et al.,

inhibition of ATCase by CTP results

because such allosteric binding by

CTP drastically reduced the affi n-

ity of ATCase for its substrate car-

bamoyl phosphate (Bethell 1968).

ATCase exists in two states: the

relaxed (R) and tense (T) states; in

the absence of a fi xed concentra-

tion of either substrate, ATCase is in

equilibrium between the two states.

ATCase has a lower affi nity for sub-

strate (and thus lower catalytic ac-

tivity) when it is in the tense state.

CTP inhibition of ATCase activity

is an example of feedback regula-

tion where the end product regu-

lates the activity of an earlier step.

The mechanism of inhibition is sta-

bilization of the tense state. ATP,

on the other hand, binds to ATCase

at an allosteric site in such a way

as to enhance the activity by sta-

bilizing its R state conformation.

I have been doing experiments

with ATCase in Professor Josh Rabi-

nowitz’s lab at Princeton for about a

year. For my experiments, Profes-

sor Evan Kantrowitz of Boston Col-

lege has generously provided me

with ATCase that has been purifi ed

from E. coli cells from his lab. My

fi rst experiments consisted of trying

to replicate data from the literature.

There has been an enormous amount

FeedbackRegulation of

ATC A S E

8

of research done on this enzyme.

For my experiments, I use a colo-

rimetric assay modifi ed from that

of Prescott and Jones and also that

of Kantrowitz. An acidic color re-

agent – which quenches (stops) the

reaction – is added to the reactions

after they have been allowed to run

for about 16 minutes. After being

incubated in the dark at room tem-

perature for at least 16 hours (dur-

ing which it reacts with the product

carbamoyl aspartate), it is then ex-

posed to fl uorescent light at 45°C

for 24 minutes (the reaction is time-

sensitive). A yellow color develops

that is linearly proportional to the

amount of carbamoyl aspartate pro-

duced during the reaction: the more

intense the yellow color, the more

product has formed. An instrument

called a spectrophotometer is used to

measure the intensity of the yellow

color at an absorbance of 466 nm.

The reactions are carried out in bo-

rosilicate glass tubes at pH 7. Water,

buffer (with a known concentration

of ATCase), and a known concentra-

tion of L-aspartate are added to each

tube. Then NTPs are added. The re-

action is initiated by the addition of

carbamoyl phosphate and is allowed

to run for 16 minutes before being

quenched with the color reagent.

At fi rst, I only experimented with

a single NTP. This was mainly

done to ensure that my experiments

produced results that matched the

literature. It was found that—in

agreement with the literature—at

pH 7, ATCase activity was in-

hibited by CTP, further inhibited

when UTP was used in combina-

tion with CTP, inhibited slightly

by GTP, and enhanced by ATP.

These experiments have already

been performed, so what is more

interesting now is the effect of dif-

ferent concentrations of multiple

NTPs on the activity of ATCase.

Recently, I have been investigat-

ing—in conjunction with Profes-

sor Herschel Rabitz’s lab, which

is modeling the data using random

sampling-high dimensional model

representation—the effect of four

NTPs (CTP, ATP, GTP, and UTP) in

combination, varying the concentra-

tions of each for each reaction tube.

The analyses from these experi-

ments are still in progress.

The study of the effects of NTPs

on ATCase provides insight into cru-

cial and interesting mechanisms in

the cell, especially that of feedback

regulation. The cell has developed

its own way of synthesizing some

of the components it needs to func-

tion as well as its own way of regu-

lating how much of the product it

produces. In the case of pyrimidine

biosynthesis, the end product of the

pathway (e.g. CTP) can inhibit the

activity of the enzyme. In doing so,

it prevents the cell from wasting its

resources and making too much of

the product. On the other hand, if

there is more end product needed,

ATP, a purine nucleotide that is not

part of that pathway, can enhance

the activity of the enzyme and in-

duce it to produce more pyrimidine.

_____________

References:

Bethell, M. R. (1968). “Carbamyl Phosphate: An Allosteric Substrate

for Aspartate Trancarbamylase of E. Coli.” Proceedings of the

National Academy of Sciences of the United States of America 60(4):

1442-49.

Else, A. J., and Herve, G. (1989). “A Microtiter Plate Assay for Aspar-

tate Transcarbamylase.” Analytical Biochemistry 186: 219-221.

England, P., Leconte, C., Tauc, P., Herve, G. (1994). “Apparent Coop-

erativity for carbamylphosphate in Escheria coli aspartate transcarba-

mylase only refl ects cooperativity for aspartate.” EJB 94: 775-80.

Gerhart, J. C., and Pardee, A.B. (1961). “The Enzymology of Control

by Feedback Inhibition.” The Journal of Biological Chemistry 237(3):

891-6.

Prescott, L. M., Jones, M.E. (1969). “Modifi ed Methods for Determi-

nation of Carbamyl Aspartate.” Analytical Biochemistry 32: 408-419.

Tymoczko, J. L., Berg, J., and Stryer, L. Biochemis-

try. 5th Ed. New York: W.H. Freeman and Co., 2002.

Wang, J., et al. (2005). “Structural basis for ordered substrate binding and

cooperativity in aspartate transcarbamylase.” PNAS 102(25): 8881-8886.

Jennifer Hsiao ‘07 is from

Windsor, CT. She is major-

ing in Chemistry with

certifi cates in Latin and

Music Performance. She is

working in the Rabinowitz

lab for her senior thesis.

9

...and are not a part of the technol-

ogy of the immediate future, but for

researchers working in technologi-

cal frontiers, the boundary between

the two realms is rapidly merging.

Such is the view of Dennis Bush-

nell of the National Aeronautics and

Space Administration (NASA).

Dennis Bushnell, invited by the

Princeton chapter of the American

Institute for Aeronautics and Astro-

nautics (AIAA), discussed the fu-

ture of NASA’s projects and space

program. Having worked at NASA

for 41 years, Bushnell is now the

chief scientist at the administration’s

Langley Center at Hampton, Vir-

ginia. Before working for NASA,

Bushnell completed his B.S. in Me-

chanical Engineering at the Univer-

sity of Connecticut and a

M.S. degree in Mechanical

Engineering at the Univer-

sity of Virginia.

He has been

fascinated by

fl ow modeling

and speed range

control research,

which was partly why

he decided to work for

NASA. Throughout his

career, Bushnell has

received numerous

awards and has been

appointed by groups

like the National Acad-

emy of Engineers.

Presently, Bushnell considers

the space program to be in crisis

because of major job cuts and re-

duced research funding. But despite

these conditions, Bushnell is confi -

dent that “things can only get bet-

ter.” In order to improve, however,

there is a tremendous need to rein-

vent. Bushnell focused on two as-

pects: the social application of past

space research and the space pro- by Kevin Kung

10

NASA Chief Scientist Discusses

and Space Program

ertical take-off, landing vehicles,

virtual reality, antimatter fuels—you may think that these belong to the realm of science fi ction...

gram of tomorrow.

The primary social application

of space-program technologies can

be divided into three groups: trans-

portation, telecommunications, and

virtual reality. With regard to trans-

portation, Bushnell concentrated on

what he called the PC version of

aviation, the automatic robotic ver-

tical take-off and landing (VTOL)

delivery vehicles. The major feature

of VTOL is that it is point-to-point,

safe, long-ranged, and automatic;

there is no need to steer. Bushnell

envisions the replacement of ordi-

nary automobiles with VTOL, ac-

companied by the civilian use of

high-resolution global positioning

system (GPS) and satellite commu-

nications. VTOL’s ability to fl y and

drive as well as its higher energy

effi ciency have many implications.

The population density along the

Eastern Seaboard can be reduced as

long-distance travel becomes more

affordable, and in turn, traffi c con-

gestions will diminish. Furthermore,

Bushnell mentioned that VTOL was

approved for possible use in future

warfare. Thus, there is potentially

a twofold market for VTOL: com-

mercial and military.

Telecommunications and vir-

tual reality are two other intricately

linked areas within NASA. In the

area of virtual reality, the success-

ful implementation of haptic touch,

smell, and taste by an M.I.T. group

in 2004 has been one such break-

through. Bushnell mentioned future

advances such as optical communi-

cations and direct brain feeds by vir-

tual stimuli. In fi ve to seven years,

he predicts many business meetings

and conferences will be held through

virtual reality, preventing the need

of extensive travel. Even ordinary

routines such as shopping may also

take the form of tele-control.

What exactly will motivate these

technological developments? Ac-

cording to Bushnell, lowered costs

and reduced traffi c congestion will

serve as a strong incentive: he es-

timates that the combined profi t for

these technologies may sum up to

one trillion dollars annually.

The other facet of NASA is the

future of the aerospace program.

The path of airplane research will

likely differ from that of spacecrafts

because the two areas of research

are surrounded by different envi-

ronmental and technical issues. In

aircraft design, Bushnell empha-

sized that it is the emission of wa-

ter vapor, instead of CO2, that will

produce the most signifi cant envi-

ronmental impact. This is because

high-altitude water vapor induces

artifi cial cirrus clouds, which in turn

alter the Earth’s albedo—the means

through which solar energy enters

and leaves the planet. Thus, while

fuel cells are an important technol-

ogy in reducing CO2 and nitrous

oxide emissions, they are equally

disastrous for NASA because the

burning of hydrogen gas produces

dangerous amounts of water vapor.

Other environmental problems re-

lated to airplanes include ozone de-

pletion, the generation of high-tem-

perature regions, and sonic booms.

Several proposals have been offered

to effectively deal with these prob-

lems. Some of them include fl ying

below 30,000 feet, storing electric-

ity in airplanes, injecting water for

take-off, managing waste products

more appropriately, and improving

aircraft design. Bushnell explored

the latter three proposals at length.

The main function of take-off water

injection is to reduce aircraft noise.

“The major feature of VTOL is that it is

point-to-point, safe, long-ranged, and

automatic; there is no need to steer.”

“In aircraft design, Bushnell em-

phasized that it is the emission

of water vapor, instead of CO2,

that will produce the most sig-

nifi cant environmental impact.“

11

Though high-altitude water vapor

creates problems, it usually poses

no signifi cant issues at ground level.

On the other hand, the emission of

waste products can be avoided by

effl ux-storage technologies such as

storing water as ice crystals to be

brought back to the ground. Concur-

rently, an important area of design

development is the so-called Pfen-

ninger strut and truss-braced wings.

The tail of an airplane in this design

actually slants forward and joins the

main wings. If the concept is opti-

mized, then a high aspect ratio can

be achieved, allowing the aircraft to

travel at high speeds (Mach 2) with-

out experiencing considerable drag

and conserving fuel.

Perhaps the fi eld most easily as-

sociated with NASA is space explo-

ration. Bushnell sums up the pres-

ent paradox as “what is safe is not

affordable and what is affordable

is not safe.” Indeed, especially af-

ter the explosion of Columbia, the

question of human and operational

safety is of paramount importance

to NASA. In addressing hazards to

humans in space, Bushnell raised

several possible solutions. For in-

stance, one method of reducing

radiation exposure is to bury the

crew inside a hydrogen gas tank. A

low-level pulsating electromagnetic

fi eld may slow down bone loss due

to microgravity. In addition, there is

the more controversial concept of

“designer humans,” whereby some

people are genetically modifi ed to

be fi t in space. In some instances, it

is advisable to reduce the number of

people in space. To achieve this end,

holographic astronauts, generated on

earth using virtual reality techniques

discussed above, may replace actual

crew. Of course, a problem with a

holographic crew is that the space-

craft is confi ned to a limited space

around the Earth: a longer distance

delays transmission. Bushnell even

hinted at 2001: A Space Odyssey, a

Stanley Kubrick fi lm from the late

1960’s, in which, for long-distance

travel, the astronaut’s hypothalamus

is suppressed, leading to suspended

animation and a lower metabolic

rate.

In addition to crew safety in long-

distance fl ights, the possession of an

affordable and effi cient power and

propulsion source is indispensable.

There are no less than eight cur-

rent areas of research. For example,

antimatter fuels and nuclear fusion

exploit the enormous amount of en-

ergy released by converting mass

to energy, drawing upon Einstein’s

proverbial equality, E = mc2. There

are also thoughts on capturing the

radiation pressure from cosmic rays

using “solar sails” and cultivating

hydrogen-fuel-producing plants or

microbes, which may be promising

not only for space fl ight but also as

a substitute for oil in cars. Bushnell

also stresses the importance of in-

space infrastructures, such as the

International Space Station (ISS), as

nodes between near-Earth and inter-

planetary travels. If some of these

technologies can be developed suc-

cessfully, then they will translate

into important applications within

our society, repeating a cycle of in-

vention and application.

In Bushnell’s view, the predicted

era of change from automobile to

“...one method of

reducing radia-

tion exposure is

to bury the crew

inside a hydro-

gen gas tank. A

low-level pulsat-

ing electromag-

netic fi eld may

slow down bone

loss due to mi-

crogravity.”

12

VTOL vehicle resembles the trans-

formation from horse to automo-

bile of the early 20th century. Both

eras, he argued, are characterized

by growths in economy, speed, and

possibility frontiers. However, he

also believes that the current transi-

tion will be easier, since, whereas a

high cost was expended to build the

infrastructure for automobiles, the

transformation from cars to VTOL

vehicles and other comparable tech-

nologies “is a matter of electrons.”

We eagerly await the technological

advances the future will bring.

translate into important applications

within our society, repeating a cycle

of invention and application.

The Bell Boeing V-22 Osprey, a successful V/STOL military aircraft designed both to

take off like a helicopter and fl y at high altitudes as a turboprop airplane.

The Moller M400

Skycar, a com-

mercial VTOL

model that its

makers hopes will

become an af-

fordable house-

hold item.

The Cosmos 1 spacecraft, designed to be

propelled by its solar sails (prominent in this

illustration), is one of the fi rst attempts to im-

plement this method of energy capture.

A physics major hailing from Taipei, Kevin Kung (‘08) has enjoyed writing for magazines such as The Innovation, besides various other exploits. He writes half what he believes, and he believes half what he writes.

13

Some of the best discoveries are

accidental. Penicillin, the x-ray,

and Velcro are some examples. Al-

though accidental discoveries are

impressive because of their nov-

elty and unpredictability, it still

takes a pioneering intellect to ap-

preciate the applicability of what

has been found. In the summer of

2006, such a discovery in hydro-

gen fuel cells was made by Jay

Benziger, Professor of Chemical

Engineering, and Claire Woo ’06.

In order to appreciate the inge-

nuity and signifi cance of the Ben-

ziger-Woo fuel cell, it is helpful to

understand the way the typical fuel

cell works. First, hydrogen fuel en-

ters the cell and is broken up into its

constituents upon reaching the an-

ode catalyst, forming a proton and

an electron. The electrolytic mem-

brane then allows the proton to fi lter

through while the electron is forced

to move around the membrane, pro-

viding a fl ow of electrons that pro-

vides the current

that produces

electric power.

The electron

and proton join

at the cathode

where they react

with oxygen to

form water. In the

typical fuel cell,

the water is then

transported out

of the fuel cell

through evacu-

ation tubes. The

power output of

the fuel cell is

related to the amount of hydrogen

fuel that enters the cell—the more

hydrogen, the more electrons, the

more current. In order to control

output, the typical fuel cell utilizes a

mechanism that modifi es the amount

of fuel allowed

to enter the cell.

What differenti-

ates the Benziger-

Woo fuel cell is that

it does not need an

external power-con-

suming mechanism

to control power

output. It regu-

lates its own power.

When Benziger

and Woo began their

research project,

their intention was

to illustrate that such

self-regulation was

impossible. Rather than designing

the fuel cell to regulate its air in-

take, which was the conventional

An accidental discovery made by Professor Jay Benziger and Claire Woo

‘06 is redesigning fuel cells in an unforeseen niche market.

// BY BRIAN LEVEE

Redesigning the

Hydrogen Fuel

Cell

Not only did the cell provide a sim-ple and effi cient water regulating

mechanism, but it also allowed the

fuel cell to maintain constant power

output without re-quiring any outside

mechanism.

14

approach to integrate self-regula-

tion into fuel cells, Benziger and

Woo designed a cell that regulates

the volume of the reaction chamber.

By allowing the water produced in

the reaction to fall to the bottom of

the chamber, rather than evacuat-

ing it through complex channels,

as was done in previous fuel cells,

they unknow-

ingly created the

new self-regu-

lating fuel cell.

If the fi gure

of the fuel cell

were turned on

its side so that

the cathode pole

that allows wa-

ter and heat to

leave the system

is on the bot-

tom, water col-

lects on the bottom of the cell due

to gravity. The water level is able to

rise or fall due to the pressure inside

the cell by attaching a tube to the

hole where the water would typi-

cally leave the cell thus allowing

the water to reach an equilibrium

level that is sensitive to air pressure.

When the pressure

inside the chamber increases due

to additional hydrogen fuel intake,

water is pushed downwards caus-

ing the volume of the chamber to

increase, thus decreasing the fuel

cell’s power output. A drop in pres-

sure causes the water level to rise

while lowering the chamber volume

and increasing power output. DYT

When their simple power

regulating cell

worked, Ben-

ziger and Woo

were aston-

ished. They

soon realized

that their design

was progres-

sive in a num-

ber of ways.

Not only did

the cell provide

a simple and

effi cient water

regulating mechanism, but it also al-

lowed the fuel cell to maintain con-

stant power output without requir-

ing any outside mechanism. This

new design increases the effi ciency

of the fuel cell by eliminat-

ing the need

to expend energy on power out-

put control and water evacuation.

In addition, whereas the typi-

cal Honda or Toyota vehicle fuel

cell converts only 30 to 40% of the

hydrogen fuel into water and power

and then relies on another mecha-

nism to retain the extra hydrogen

fuel that was left over for the next

cycle, the Benziger-Woo fuel cell

is nearly 100% effi cient. The wa-

ter at the bottom of the chamber

blocks all escape paths during the

reaction, causing the chamber to

be securely enclosed, allowing it

to be perfectly effi cient, bypassing

the need for hydrogen clean-up.

Benziger explains that their

“work is leading the way for think-

ing about how to redesign the

fuel cell as a chemical reactor.”

Rather than using the fuel cells in au-

tomobilesDYT, which is the primary

focus of most private hydrogen fuel

cell developers, the newly designed

fuel cell will function mainly in

small engines, such as lawn mowers.

According to Benziger, the small en-

gine mar-

15

Whereas the typical Honda or Toyota ve-

hicle fuel cell converts only 30 to 40% of the

hydrogen fuel into power, the Benziger-Woo fuel cell is nearly

100% effi cient.

Professor Benziger in his

lab at Princeton.

ket is a major source of pollution in

suburbia because such engines lack

emission controls and therefore most

are highly polluting. The Benziger-

Woo design holds a signifi cant po-

tential for reducing such pollutants.

The Benziger-Woo fuel cell also

provides the most utility to small

engines because in small fuel cells,

a large portion of the power out-

put is used for regulating and ex-

porting water. In small engines,

like lawn mowers, the new design

may save a signifi cant percentage

of the power output, causing the

Benziger-Woo fuel cell to be more

economically viable in this niche

rather than in larger engines where

the extra power is less signifi cant.

Unlike the serious infrastructural

problems facing fuel cell-powered

automobiles, the use of this tech-

nology in smaller engines would

not present such a problem. Hy-

drogen fuel could be bought from

stores and plugged into fuel cell

devices in the same way that pro-

pane is purchased to fuel barbeques.

Although their innovation will

probably not reshape contemporary

electronics, it holds great promise

for solving a myriad of technical

problems making hydrogen fuel

cells more effi cient and useful to an

environmentally conscious world.

My intended major is either

EE or physics. I am a fresh-

man from Los Angeles. I

don’t surf, but I live a few

blocks from the beach. I

know, its a crime.

Hydrogen fuel could be bought from stores and plugged into fuel cell devices in the same way that propane is purchased to fuel barbeques.

17

Plasmodium merozoites being released from

a lysed red blood cell.

Genetically Engineered

MalariaResistant

New advances in the

development of ma-

laria-resistant mosquitoes

suggest that when a cure

for malaria is discovered

it may bring about a new

breed of mosquitoes rather

than a vaccine. For de-

cades, scientists have been

working to create a ma-

laria vaccination to combat

the widespread mosquito-

borne infectious disease

that kills between 700,000 and

2.7 million people every year

. Some biologists, however,

have been working on devel-

oping genetically engineered

mosquitoes which are immune

to the disease and thus can not

transmit the disease to humans.

Two recent breakthroughs in

this line of genetic engineer-

ing may prove to be more in-

strumental in eradicating ma-

laria than the ongoing search

for a vaccine has ever been.

Jason Rasgon, a professor of

microbiology and immunology

at Johns Hopkins University, led

a research team that developed a

breed of mosquitoes resistant to

Plasmodium berghei, the strain

of malaria that infects mice. An-

other study, led by molecular bi-

ology professor Anthony James

from the University of California

at Irvine, genetically engineered

mosquitoes that are resistant to

Plasmodium gallinacium, the

malaria parasite for chickens.

Although researchers have yet

to develop a breed of mosqui-

toes resistant to human malaria,

these two studies represent ma-

jor progress towards that goal.

The mouse and chicken strains

of malaria are easier to manipu-

late for laboratory research than

the human strain, and although

they, represent fairly accurate

models for the human strain, the

parasites are not entirely similar.

Malaria is caused by Plas-

modium parasites that are trans-

mitted by female Anopheles

mosquitoes. The mosquitoes

consume the parasites while

feeding, and, once ingested, the

Plasmodium parasite’s male and

female gametes fuse and form

an ookinete in the mosquito’s

gut. The ookinete then devel-

ops into an oocyst that releases

sporozoites. The sporozoites

move through the mosquito’s

circulatory system to the sali-

vary glands and are then in-

jected into a human host when

the mosquito bites a person.

// BY JOSEPHINE WOLFF

Mosquitoes

18

Different scientists have attempted

to target the Plasmodium parasites

and eliminate them in the engi-

neered mosqui-

toes at different

points in the

parasite’s life

cycle. James’

research team

created a gene

that produces

an antibody for

a protein found

in the Plasmodi-

um sporozoites.

The research-

ers introduced

the gene into

the mosqui-

toes by in-

fecting them with a virus and the

mosquitoes effectively eliminat-

ed 99.99% of the sporozoites in

the mosquitoes’ salivary glands.

Initially, scientists struggled with

the challenge of

how to geneti-

cally modify the

Anopheles mos-

quito. In order

to alter the ge-

netic code, they

needed to attach

a new gene to a

transposon (short

piece of DNA)

that would incor-

porate itself into

the mosquito’s

genome. This

process had been

successfully im-

plemented with

fruit fl ies using

the P transposon.

However, research-

ers discovered that the same trans-

poson used in fruit fl ies did not suc-

cessfully modify

the genome of

m o s q u i t o e s .

In the 1990s,

researchers at

the University

of Maryland at

College Park

and the Univer-

sity of Califor-

nia at Riverside

discovered a

new series of

t r a n s p o s o n s

including the

Hermes trans-

poson, which

biologists found

could be used to successfully modify

the genome of Anopheles mosquitoes.

The advances made by Ras-

gon and James suggest that it will

not be long before a mosquito re-

sistant to human malaria can be en-

gineered. Once that task is accom-

plished, however, scientists will

face the obstacle of replacing the

existing mosquito population with

the new malaria-resistant breed.

Since the malaria disease affects

mosquitoes as well as humans, the

resistant mosquitoes would have a

signifi cant advantage over the non-

engineered mosquitoes. Rasgon’s

team performed a study showing

that, in a population with equal

numbers of the malaria-resistant

mosquitoes and regular mosquitoes,

after nine generations, the geneti-

cally-engineered mosquitoes com-

prised over 70 percent of the popu-

lation. These results indicate that

if enough of the engineered mos-

quitoes were released, they could

rapidly eliminate a large majority

of the malaria-carrying mosquitoes

by the process of natural selection.

There would be no need to resort to

the use of environmentally-hazard-

ous pesticides. Though these stud-

ies are promising indicators of a fu-

ture end to malaria, Rasgon warns

that “we’re not anywhere near a

fi eld release.” The continued devel-

opment of well-engineered malaria-

resistant mosquitoes is undoubt-

edly bringing biologists closer and

closer to ultimately fi nding a cure.

The advances made by Rasgon and

James suggest that it will not be long before a mosquito resistant to human

malaria can beengineered.

How malaria from a parasite infects its host.

Josephine Wolff is a freshman

from Cambridge, MA. She

hopes to study math or archi-

tecture and pursue a certifi -

cate in French. She also enjoys

sudoku puzzles, playing the pi-

ano, Grey’s Anatomy, the Bos-

ton Red Sox, and the New York

Times Sunday Styles section.

19

If you were a lung cancer pa-

tient, your fi ve-year survival rate

would be around 6 percent for men

and 7 for women. That very sta-

tistic itself could almost obliterate

your hope for life, but a new pill

on the market approved by the

FDA could change that. Online

fan clubs and doctors worldwide

are hailing the drug as the most

successful cancer drug in history.

Approved in over 70 countries,

this drug is not your typical ex-

tensively chemotherapy-backed,

side-effects-ridden drug. Its name

is Alimta and it could just make

battling cancer that much easier.

Dr. Edward C. Taylor of Princ-

eton University developed Alimta

in collaboration with Eli Lilly and

Company. Dr. Taylor is the A. Bar-

ton Hepburn Professor of Organic

Chemistry, Emeritus at Princeton.

He is one of the world’s foremost

experts on heterocyclic compounds

and was previously a consultant for

Eli Lilly. He did his undergraduate

and graduate studies at Cornell. Sur-

prisingly, chemistry was not even

on his radar until late in high school.

He was planning to do English, but

after taking one chemistry class he

became so enticed by the subject

that he went on to take all of them

his school had offered. The discov-

ery of Alimta was not his expected

goal. He jokes in a speech given

at Princeton “No one would want

to fund a project on the investiga-

tion of pigments in butterfl y wings.”

He points out that the lesson to be

learned is the importance of origi-

nal inquiry and he reminisces about

“the golden days when researchers

didn’t have to know the outcome

before starting a project.” When

Dr. Taylor sent the fi rst sample of

his new compound to Eli Lilly for

tests, the company sent a letter to

him saying there must have been

a mistake and further

trials were needed.

When he received a

second letter, Eli Lilly

apologized to him and

said there was actu-

ally no mistake. They

were just extremely

surprised that all types

of cancer cells reacted

to his new compound.

In February 2004

after 12 long years of

clinical trials, Dr. Tay-

lor’s drug that goes

by the brand name of

Alimta also known as

Pemetrexed (C20H21N5O6 ) was

fi rst approved by the FDA for treat-

ment of non-small cell lung cancer

and malignant pleural mesothelio-

ma. Mesothelioma often surfaces

approximately forty years after ex-

posure to asbestos, and its effects

are only now beginning to emerge.

Luckily, however, this latency peri-

od has allowed Alimta to be devel-

Professor emeritus Edward Taylor de-

veloped Alimta at Princeton.

“When Dr. Taylor sent the fi rst sample of his new

compound to Eli Lilly for tests, the company sent a letter to him saying there

must have been a mistake. When he received a second

letter, Eli Lilly apologized and said there was actually no mistake. They were just extremely surprised that

all types of cancercells reacted to hisnew compound. “

Taylor’s miracle cancer drug: Alimta// BY DAVID TAO

20

oped just in time to treat it. Alimta

is in a chemical group similar to fo-

lic acid known as antimetabolites,

and therefore, patients must be on

folic acid and vitamin B12 supple-

ments during the course of their

therapy. Alimta functions by inhib-

iting three enzymes used in purine

and pyrimidine synthesis—thymi-

dylate synthase (TS), dihydrofolate

reductase (DHFR), and glycinamide

ribonucleotide formyl transferase

(GARFT). This stops the precur-

sors to nucleotide formation

thereby preventing the syn-

thesis of the DNA and

RNA of cancer cells.

A major ad-

vantage of

Alimta is the

minimal pre-

ventive measures

needed to counteract the side effects

of the drug as compared to traditional

chemotherapeutic procedures. Five

to seven days before the fi rst Alim-

ta injection, the patient is required

to take a folic acid pill once every

day. Folic acid can counteract the

anemia associated with vitamin B12

defi ciency over the course of the

therapy. 350 to 1000 mg

should continue to be

taken until

21 days after

the last cycle

of Alimta. The

d o c t o r

will inject

vitamin B12

the week the patient

starts on Alimta and

then every 9 weeks after that.

The use of an oral steroid called

dexamethasone will minimize the

risk of a skin rash. What is most

surprising is that this is also an out-

patient treatment, almost unheard

of in treatments against cancer.

In addition, the side effects of this

regimen amount to those character-

istics of a minor fl u including nau-

sea, fever, sore throat, and loss of

appetite. Compare this with those

of traditional chemotherapy, usually

involving a combination of immune

suppression, radiation therapy, and

surgery with serious well-known

side effects such as hair loss, ane-

mia, malnutrition, cardiotoxicity,

and even death. Currently, Alim-

ta is under clinical trials for a host

of other cancers. Dr. Taylor said

“We have had complete cures of

breast cancer, but it has not been

approved yet and the treatment of

colon cancer has been effective at

Mayo Clinic.” Treatments of some

are more effective than others, but

Dr. Taylor hopes that some day Al-

imta can replace or supplement many

of the other procedures and reduce

the suffering of cancer patients. His

contributions to chemistry and med-

icine have earned him the Heroes in

Chemistry Award from the Ameri-

can Chemical Society and will con-

tinue to offer hope to thousands of

cancer patients around the world. 1

1 “Cancer Survival Rates Improved During 1998-

2001,” National Statistics Online, http://www.statis-

tics.gov.uk/cci/nugget.asp?id=861 (accessed March

20, 2007).

2 Wikipedia.org, s.v. “Alimta”, http://en.wikipedia.

org/wiki/Alimta (accessed March 20, 2007).

3 Ibid.

4 “Treatment with Alimta,” Alimta.com, http://

www.alimta.com/treatment/treatment/index.

jsp?reqNavId=2.1 (accessed March 21, 2007).

5 “Alimta,” Drugs.com, September 29, 2006,

http://www.drugs.com/alimta.html (accessed March

21, 2007).

6 Wikipedia.org, s.v. “Chemotherapy”, http://

en.wikipedia.org/wiki/Chemotherapy (accessed

March 20, 2007).

Structural drawing of Alimta

From Lexington, KY

Princeton Class of 2010

Potential molecular biol-ogy major and neurosci-ence minor.

21

The Art of Choosing WellSM

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service providers. PharmaNet provides an unrivaled combination of experienced project management

teams, senior management oversight, and an exclusive approach to building cooperative relationships

with sponsors. For comprehensive Phase I–IV services in clinical development and consulting, choose

your CRO wisely. Choose PharmaNet.

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© 2007 PharmaNet Development Group, Inc. All rights reserved. 0307.9989.

The PharmaNet name, logo, and The Art of Choosing Well are marks of PharmaNet Development Group, Inc.

Learn more about the premier global CRO serving

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The Science and Ethics Behind Drug Testing and Clinical StudiesSniffl es, a scratchy throat, and

a throbbing headache. Upon

rushing off to the doctor’s offi ce,

eager to get antibiotics, one hardly

stops to think of the creation and

evolution of the desired medication.

In fact, drugs undergo a lengthy

process from lab tests to an eventual

approval by the FDA before they

can be sold on the pharmaceutical

market. Pharmanet, for instance, is

a company involved in the regula-

tion of the clinical studies in drug

development held subsequent to the

drug-discovery phase in laborato-

ries.

A company like Pharmanet is em-

ployed by a pharmaceutical compa-

ny looking to market a new medi-

cation and carries out and oversees

all phases of the drug study. There

are four such phases of testing that

a drug must undergo before it gains

FDA approval. Phase I is primarily

focused on toxicity studies wherein

patients are subjected to what is

known as “dose escalation studies.”

In these studies, the participants are

given a certain dosage of the medi-

cine that is gradually and incremen-

tally increased to fi nd the maximum

tolerated dose of the drug. Given

the nature of Phase I, patients par-

ticipating in the study are likely not

expecting full treatment or recovery

but rather are volunteering with the

understanding that there is no guar-

antee that the drug will even pro-

duce the desired effects. Following

this, Phase II involves the actual tar-

geting of the population of patients

that would be treated in a real world

setting; thus the aim of these stud-

ies is effi cacy, understanding how

well the drug in question cures a

particular illness. These studies are

small in scale, involving no more

than 10-20 hospitals and approxi-

mately one hundred patients. Phase

III continues to focus on the patients

targeted for use of a specifi c drug.

These studies are large in scale, of-

ten global, and yield enough data for

the FDA to decide whether or not to

approve the drug. Phase IV, the fi -

nal stage, involves thousands of pa-

tients taken from large patient reg-

istries. Participants in these studies

will often buy a drug with the un-

derstanding that their results will be

documented and used for these larg-

er-scale studies. This phase tends to

focus on the long-term effects of the

drug and is consequently conducted

after the drug has been approved by

the FDA and sold on the market (i.e.

post marketing studies), and compa-

nies often use this phase to expand

their label.

This entire process (Phases I-IV) can take anywhere from 7-10 years, and its du-ration depends heavily upon how quickly companies can recruit the patients needed for the study.

Given the apparent complexity,

there are several regulatory steps

designed to keep the tests both ethi-

cally and scientifi cally sound. There

are two boards in particular that

monitor the studies – the Data Safe-

ty Monitoring Board and the Insti-

tutional Review Board (IRB). The

Data Safety Monitoring Board is ac-

tive during phases II-IV, reviewing

the data (often blindly) and decid-

ing whether or not to push the study

through to the next phase. Thus,

they look at the data and judge from

a scientifi c standpoint whether or

not it makes sense to move on with

a study. The IRB on the other hand,

is concerned less with what makes

sense from a scientifi c or logical

standpoint, and more

by Sarah Weinstein

23

with whether or not the studies are

ethically sound. At any point in the

study, the IRB is capable of putting

an end to the

tests on ethical grounds.

Clinical drug studies present

the companies with myriad press-

ing ethical issues. One of the fi rst

and most important considerations

of a company conducting medici-

nal studies is ensuring that the par-

ticipants are adequately informed

about all the procedures and pos-

sible outcomes of the study. Prior

to recently mandated informed

consent forms, there was little

regulation in this area, and in fact,

these measures were developed in

response to ethically repugnant ex-

periments where the participants

were not adequately informed

about the study. The Tuskegee

Experiment (1932-1972), for in-

stance, was one of the most serious

and notable studies gone morally

awry. In this experiment, the phy-

sicians involved were aware that

the participants were infected with

syphilis, a serious sexually trans-

mitted disease, and knowing this

only told the patients that

they were being treated

for “bad blood” and in

fact offered next to no

treatment. Essentially,

the physicians know-

ingly did nothing for the

patients and instead

followed the prog-

ress of the disease

to completion.

The partici-

pants of the study,

who were mostly poor, uneducated

sharecroppers from Alabama were

deliberately misled in order to en-

sure their full participation.

At one point, the patients were duped into participat-ing in a dangerous spinal tap with a letter that was sent out entitled “Last Chance for Special Free Treatment.”

The Tuskegee experiment has been

referred to as “the longest nonthera-

peutic experiment on human beings

in medical history1,” and indeed, the

experiment had severe consequenc-

es. After the forty years of experi-

mentation, 28 of the men had died

of syphilis, 100 had died of related

complications, 40 of their wives had

been infected, and 19 of their chil-

dren had been born with congenital

syphilis. Thus, when the full gamut

of the researchers’ ethical transgres-

sions were revealed to the public,

it became painstakingly clear that

stricter regulations were necessary.

A second more circumstantial

ethical issue in clinical studies aris-

es when a particular patient wants to

participate in a study but for what-

ever reason does not qualify. For

instance, oncology studies often re-

quire of their patients a certain white

blood cell count; patients falling be-

low the desired count would not be

admitted to the study. In this case,

Phases of Clinical Drug Trials:

Phase II: effi cacy studies

Phase III: global effi cacy studies

Phase IV: long term effects

and post-marketing studies

Phase I: toxicity and dosage studies

Upon rushing off to the doctor’s offi ce, eager to get an-

tibiotics, one hardly stops to think of the creation

and evolution of the desired medication.

24

the doctors are aware that on the

one hand the patient might benefi t

signifi cantly from having access to

this medicine, but on the other hand,

they are conscious of the fact that

allowing a participant who failed

to meet the necessary requirements

is likely to contaminate the results.

Most companies are thus rather strict

about not allowing unqualifi ed par-

ticipants into the study. However,

some patients can acquire what is

known as a single patient IND (in-

vestigational new drug) on a “com-

passionate use basis.” This type of

exception allows one patient to get

the drug apart from the study for

one cycle of treatment even though

the drug is not FDA-approved.

Finally, the most widely dis-cussed ethical issue con-cerning clinical drug studies is the use of placebos for studying the treatment of serious medical conditions.

Along the same lines as the last eth-

ical conundrum, the use of placebos

is essentially the purposeful non-

treatment of a condition that is po-

tentially terminal – one that might

theoretically be cured by dispensing

the actual drug to all test subjects.

To avoid this problem, drug com-

panies often will give the standard

treatment to one group of patients,

and to the second group they will

give the standard treatment plus the

experimental drug, so that each pa-

tient is at least receiving some form

of treatment. When it is impossible

to incorporate a standard drug into

the study, then patients who are ini-

tially given only placebos later have

access to the experimental drug

– once the study is concluded.

The current system of clinical

drug testing is long and painstaking,

compounded by a series of ethical

concerns, and yet it is only one small

step in the larger process taking a

drug from its inception to a shelf

in your local pharmacy. Perhaps in

leaving the drug store, antibiotics in

hand, you might stop to consider the

complexity and evolution of drug

development and the years of labo-

ratory work and clinical testing that

made your purchase possible.

1 Encylopedia Brittanica.

A man being treated during

the Tuskegee Experiment,

which involved the delib-

erate withholding of treat-

ment information from citi-

zens suffering from syphilis.

Sarah is a junior in the

philosophy department

pursuing certifi cates in

French and music per-

formance. She is from Ft.

Lauderdale, Florida but

secretly loves the snow.

25

// BY JILL FEFFER

According to chemistry profes-

sor Michael Hecht, Alzheim-

er’s disease (AD) is becoming “a

number one health problem” be-

cause people are living longer now-

adays. AD has become prevalent

because the average human lifespan

has been lengthened by advances in

medical technology. He elaborated

that AD is a “post-evolutionary dis-

ease,” meaning it was not eradicated

by natural selection because it only

strikes after the reproductive age and

at an age that people did not natu-

rally live to see, so it was never an

evolutionary concern. According to

the Alzheimer’s Association’s web-

site, “one in 10 individuals over 65

and nearly half of those over 85 are

affected.” The most apparent symp-

toms of AD are loss of memory and

cognitive functions, and physiologi-

cal signs of AD include the degener-

ation of neural cells and the growth

of protein tangles in the brain.

Evidence from previous scien-

tifi c studies indicates that a certain

threshold of protein tangle accumu-

lation is associated with the onset

of AD, so Dr. Hecht rationalized

that an effective treatment would

only have to slow the aggregation

process enough to keep accumula-

tion below this threshold, not stop

it entirely, which would be a more

daunting task because protein ag-

gregation is a naturally occurring,

constant process in the brain. In

fact, it is estimated that there is a

mere 20% difference in the accumu-

lation totals between

non-AD patients and

those affl icted with

the disease. The

realistic research

goal is therefore to

fi nd a way of delay-

ing the threshold

level of accumula-

tion for a few years,

thereby delaying the onset of

AD, perhaps permanently if the

lag is long enough for people to

die of something else in old age.

This particular physiological

marker provides the basis for one

ongoing research project in Hecht’s

chemistry laboratory. As a result of

an investigation into the molecular

causes of AD, he has developed an

inexpensive method for screening

libraries of small organic molecules

for inhibitors of the aggregation of

the protein A-ß-42, a known com-

ponent of the amyloid

protein plaque that

builds up in the brains

of AD patients, with

the hope that their

identifi cation will lead

to a preventive treat-

ment. The screen is

advantageous because

it is high-throughput,

meaning it can test many candidates

at once; it is cost-effective; it is selec-

tive for inhibition at earlier stages of

amyloid accumulation; and its trials

are relatively easily reproducible.

Professor Michael Hecht developed the

screen in his Princeton chemistry lab.

Screening for inhibitors of proteinaggregation to halt the onset of

Alzheimer’s Disease

26

The screen is a promising initial tool for selecting

proteins that mer-it further scrutiny.

The screening process employs the

common biological method of iden-

tifying inhibitors by monitoring the

activity level of a reporter protein.

In this case, A-ß-42 is fused to green

fl uorescent protein (GFP) from jel-

lyfi sh. GFP activity is easy to deter-

mine because, as the name suggest,

it fl uoresces. This protein folds into

an active state at a much slower

rate than A-ß-42 aggregates, so in

the absence of an inhibitor, A-ß-42

will aggregate quickly and interfere

with GFP’s folding process. Conse-

quently, the fused GFP will only be

able to fold correctly and fl uoresce

if the fused A-ß-42 does not aggre-

gate because an inhibitor is present.

This screen

avoids the pit-

fall of being

prone to gener-

ic inhibitors of

protein folding

because GFP

folding would

be likewise in-

hibited by them.

In the initial

execution of the

screen, a library

of approximate-

ly 1000 triazine compounds (a class

of organic molecules with the em-

pirical formula C3H3N3) was test-

ed for inhibitory capacity toward

A-ß-42 aggregation in the following

manner: E. coli cells containing the

genes to express the fused protein

were distributed into 96 wells. In-

dividual candidate molecules from

the library were added to each well

and an activator, isopropyl-ß-D-

thiogalactopyranoside, was added

to induce production of the fused

protein. The setup was then incu-

bated for three hours be-

fore an automated plate

reader checked for fl uo-

rescence. Samples were

screened multiple times

and consistent fl uores-

cent positives, or “hits,”

were identifi ed as pos-

sible A-ß-42 aggrega-

tion inhibitors. Subse-

quent experiments have

proven that a compara-

ble screen, although less

effi cient, can be performed in vitro

rather than in E. coli cells to detect

the same hits so the hits are not con-

tingent on the presence of bacterial

cells. Electron microscopy results

have confi rmed the

inhibitory capac-

ity toward A-ß-42 of

many proteins iden-

tifi ed as hits by the

screen. Thus, the

screen is a promising

initial tool for select-

ing proteins that mer-

it further scrutiny.

Dr. Hecht said the

original AD-related

experiment involved

mutating parts of

A-ß-42 to see how to prevent ag-

gregation. The idea for utilizing

GFP as a reporter protein arose

separately, from a 1999 paper about

proteomics, specifi cally testing the

solubility of proteins. Initially, his

laboratory wanted to use this tech-

nique for devising solubility for

proteins they generated de novo.

The two strains of thought eventu-

ally merged to produce the screen,

which was published in 2006.

Currently, a graduate student

from Dr. Hecht’s laboratory is at

the Broad Institute at MIT using the

screen to test libraries there for in-

hibitory capacity. Once inhibitors

are identifi ed, the next steps would

be to perform specialized research

such as animal studies in order to

eventually produce something that

is clinically useful such as pharma-

ceuticals that can be preventive rath-

er than therapeutic, as all presently

available treatments for AD are. Dr.

Hecht hopes the screen’s potential to

“turn partial chemical effectiveness

into full effectiveness at the pub-

lic health level” will be recognized

in time to save many aging Baby

Boomers and their families from the

drawn-out suffering caused by AD.

____________________

Kim W, Kim Y, Min J, Kim DJ, Chang

YT, & Hecht MH (2006) A High-Through-

put Screen for Compounds That Inhibit

Aggregation of the Alzheimer’s Peptide.

ACS Chemical Biology 1, 461-469.

Jill is a sophomore from New York

majoring in molecular biology. She

plays fl ute and is Business Manager

for the Wind Ensemble. In addi-

tion to the biology and chemistry

involved, Jill is personally interested

in research that holds promise for

treating Alzheimer’s disease.

27

Once inhibitors are identifi ed, the next steps would be to

perform specialized research such as ani-mal studies in order

to eventually produce something that is clini-

cally useful

A protein inhibitor at work.

Two New CoursesComing Next Fall

Science Journalism

STC 349 Professor Michael D. Lemonick

Develop your science writing skills from a jour-nalism perspective and learn how to present complex material about science and technology for non-technical readers. Through class discus-sion, analysis of published writing exercises, as well as interviews with Princeton scientists, participants will learn to write about science with both clarity and style.

Health and Human Rights in the

World Community

STC 398Allen S. Keller

Interested in the relationship between health and human rights? Learn about human rights viola-tions in the world today and analyze their health consequences. In this course you will consider how individual and community health can be improved by protecting and promoting human rights. You will also explore the role of the health professional in caring for victims of human rights abuses, documenting the health consequences of human rights violations, and participating in hu-man rights advocacy in education.

Fountain of Youth Lecture

2007 Evening Lecture

Genes from theFountain of Youth

From Worms to Mammals:Genes that Control theRate of Aging

Thursday, May 3, 2007

PROFESSOR CYNTHIA KENYON

Herbert Boyer Distinguished Professor

of Biochemistry and Biophysics,

University of California,

San Francisco

8:00 p.m. Reynolds Auditorium,

McDonnell Hall

The Gregory T. Pope ‘80 Prize for Science WritingAwarded annually to a graduating senior for an outstanding article on a scientiÞ ctopic written for a broad audience. This article may be based on work previously

submitted or be original work, but may not exceed 3000 words.

Entry deadline: May 15, 2007Award presented: Class Day: June 4, 2007

Prize: $500