Drug delivery systems

Drug delivery refers to approaches, formulations, technologies, and systems for transporting a pharmaceutical compound in the body as needed to safely achieve its desired therapeutic effect.[1] It may involve scientific site-targeting within the body, or it might involve facilitating systemic pharmacokinetics; in any case, it is typically concerned with both quantity and duration of drug presence. Drug delivery is often approached via a drug's chemical formulation, but it may also involve medical devices or drug-device combination products. Drug delivery is a concept heavily integrated with dosage form and route of administration, the latter sometimes even being considered part of the definition.[2]Drug delivery technologies modify drug release profile, absorption, distribution and elimination for the benefit of improving product efficacy and safety, as well as patient convenience and compliance. Drug release is from: diffusion, degradation, swelling, and affinity-based mechanisms.[3] Most common routes of administration include the preferred non-invasive peroral (through the mouth), topical (skin), transmucosal (nasal, buccal/sublingual, vaginal, ocular and rectal) and inhalation routes.[4][5] Many medications such as peptide and protein, antibody, vaccine and gene based drugs, in general may not be delivered using these routes because they might be susceptible to enzymatic degradation or can not be absorbed into the systemic circulation efficiently due to molecular size and charge issues to be therapeutically effective. For this reason many protein and peptide drugs have to be delivered by injection or a nanoneedle array. For example, many immunizations are based on the delivery of protein drugs and are often done by injection.Current efforts in the area of drug delivery include the development of targeted delivery in which the drug is only active in the target area of the body (for example, in cancerous tissues) and sustained release formulations in which the drug is released over a period of time in a controlled manner from a formulation. In order to achieve efficient targeted delivery, the designed system must avoid the host's defense mechanisms and circulate to its intended site of action.[6] Types of sustained release formulations include liposomes, drug loaded biodegradable microspheres and drug polymer conjugates. What are drug delivery systems?Drug delivery systems are engineered technologies for the targeted delivery and/or controlled release of therapeutic agents.Drugs have long been used to improve health and extend lives. The practice of drug delivery has changed dramatically in the last few decades and even greater changes are anticipated in the near future. Biomedical engineers have not only contributed substantially to our understanding of the physiological barriers to efficient drug deliverysuch as transport in the circulatory system and drug movement through cells and tissuesthey have contributed to the development of a number of new modes of drug delivery that have entered clinical practice.Yet, with all of this progress, many medications, even those discovered using the most advanced molecular biology strategies, have unacceptable side effects due to the drug interacting with parts of the body that are not the target of the drug. Side effects limit our ability to design optimal medications for many diseases such as cancer, neurodegenerative diseases, and infectious diseases.Drug delivery systems control the rate at which a drug is released and the location in the body where it is released. Some systems can control both.How are drug delivery systems used in current medical practice?Clinicians historically have attempted to direct their interventions to areas of disease or areas at risk for disease. Depending on the medication, the way it is delivered, and how our bodies respond, side effects sometimes occur. These side effects can vary greatly from person to person in type and severity. For example, an oral drug for seasonal allergies may cause unwanted drowsiness or an upset stomach. Administering drugs locally rather than systemically (affecting the whole body) is a common way to decrease side effects and drug toxicity while maximizing a treatments impact. A topical (used on the skin) antibacterial ointment for a localized infection or a cortisone injection of a painful joint can avoid some of the systemic side effects of these medications. There are other ways to achieve targeted drug delivery, but some medications can only be given systemically.What technologies are NIBIB-funded researchers developing for drug delivery?Current research on drug delivery systems can be described in four broad categories: routes of delivery, delivery vehicles, cargo, and targeting strategies.Routes of DeliveryMedications can be taken in a variety of waysby mouth, by inhalation, by absorption through the skin, or by intravenous injection. Each method has advantages and disadvantages, and not all methods can be used for every medication. Improving current delivery methods or designing new ones can enhance the use of existing medications.

Image of microneedle patch the size of a fingertip used to deliver influenza vaccines. Photo Credit: Dr. Mark Prausnitz, Georgia Institute of TechnologyMicroneedle arrays are one example of a new method to deliver medications through the skin. In these arrays, dozens of microscopic needles, each far thinner than a strand of hair, can be coated or filled with a medicine. The needles are so small that, although they penetrate the skin, they dont reach nerves in the skin, thus delivering medications painlessly.NIBIB-funded scientists are developing a microneedle patch for vaccine delivery. These patches are easy to use, do not need to be refrigerated, and dont require special disposal methods, so they could be used by patients themselves at home. Such technology could be especially helpful in rural communities that may not have many health care providers or adequate storage facilities for traditional, refrigerated medicines.Delivery VehiclesJust as its easier to carry a drink in a glass rather than on a plate, finding the right carrier for medications helps to ensure they arrive at their destination intact.NanospongesExternal link Please review our disclaimer, created by NIBIB-funded researchers, are a promising vehicle in treating cancer. Comprising a scaffold of tiny, specialized polyester particles coated with disease-targeting compounds and filled with an anticancer drug, the nanosponges home in on tumors after being injected into the body. Once at their intended site, they safely and slowly degrade, releasing medication at the tumor site at a steady, controlled rate. Early studies have also shown the nanosponges can be used to treat glaucoma, the fourth leading cause of blindness.By limiting the release of medications throughout the body, the nanosponge and related biotechnologies may revive the use of drugs that were previously unsafe for disease treatment. Beyond broadening treatment options, targeted vehicles for drug delivery may also help to address multi-drug resistant diseases.CargoPerhaps the most obvious route to improving disease treatment would be to focus on the medications themselves. But there are also other treatment options. Drug delivery researchers are also exploring the use of genes, proteins, and stem cells as treatments.

Tiny biodegradable particles for antigen couplingSource: Lonnie Shea and Stephen MillerOne example of a protein treatment is being examined in an NIBIB-funded project to treat autoimmune disorders, in which the bodys own defense system mistakenly attacks and destroys healthy tissue. Current treatments generally involve drugs that reduce the overall activity of the immune system, which also increases a persons risk of infections and other illnesses.Taking cues from the bodys natural process for preventing the immune reaction, the researchers developed microscopic, biodegradable particlesthat can selectively shut down immune cells associated with the autoimmune disorder multiple sclerosis (MS). Bound with pieces of the protein myelin, the insulating material covering nerve cells that is destroyed in MS, the microparticles were effective at preventing the start of MS in mice and at stopping disease progression when injected after the first sign of illness. The microparticle therapy may also be useful in treating other immune-related conditions, including allergies, or to suppress organ rejection in transplant patients.Targeting StrategiesWorking backwards on a problem can sometimes reveal a solution. In drug delivery research, this means starting with a delivery method that has a known target, which may be whole organs (heart, lung, brain), tissue types (muscle, nerve), disease-specific structures (tumor cells), or structures inside of cells.NIBIB-funded researchers developed a plant virus nanoparticle that can target and attach itself to prostate cancer cells. When labeled with fluorescent dyes, the viral nanoparticles can show researchers whether cancer cells have spread into bone at earlier stages of the disease than with traditional bone scans.Made from modified viruses, viral nanoparticles take advantage of the natural ways that viruses have developed to slip past immune defenses and enter cells. This means they do not need to be modified as much as other types of nanoparticles to behave in desired ways, and their actions within the human body are well understood. Plant-based viral nanoparticles are also biodegradable, harmless to humans, easy to use, and cheap to produce.Further research aims to develop viral nanoparticles that can deliver chemotherapy drugs directly to tumors. Such an advance would reduce the severe side effects usually associated with cancer treatment.What are some important areas for future research in drug delivery systems?As scientists study how diseases develop and progress, they are also learning more about the different ways our bodies respond to illness and the influence of specific environmental or genetic cues. Coupled with advances in technology, this increased understanding suggests new approaches for drug delivery research. Key areas for future research include:Crossing the Blood-Brain Barrier (BBB) in Brain Diseases and DisordersWhen working properly, the various cells that comprise the BBB constantly regulate the transfer of essential substances between the bloodstream and the central nervous system, as well as recognize and block entry of substances that may harm the brain. Delivering drugs into the brain is critical to the successful treatment of certain diseases such as brain tumors, Alzheimers disease, and Parkinsons disease, but better methods are needed to cross or bypass the BBB. One method currently under study uses advanced ultrasound techniques that disrupt the BBB briefly and safely so medications can target brain tumors directly, with no surgery required.Enhancing Targeted Intracellular DeliveryJust as our immune systems defend our bodies against disease, each of our cells also has internal processes to recognize and get rid of potentially harmful substances and foreign objects, which may include drugs enclosed in targeted delivery vehicles. So as researchers work to develop reliable methods of delivering treatments to targeted cells, further engineering is still needed to ensure the treatments reach the correct structures inside cells. Ideally, future health care will incorporate smart delivery systems that can bypass cellular defenses, transport drugs to targeted intracellular sites, and release the drugs in response to specific molecular signals.Combining Diagnosis and TreatmentThe full potential of drug delivery systems extends beyond treatment. By using advanced imaging technologies with targeted delivery, doctors may someday be able to diagnose and treat diseases in one step, a new strategy called theranostics Flavonoids: definition, structure and classification What are flavonoids?Flavonoids are the most abundant polyphenols in human diet, representing about 2/3 of all those ones ingested. Like other phytochemicals, they are the products of secondary metabolism of plants and, currently, it is not possible to determine precisely their number, even if over 4000 have been identified.In fruits and vegetables, they are usually found in the form of glycosides and sometimes as acylglycosides, while acylated, methylated and sulfate molecules are less frequent and in lower concentrations.They are water-soluble and accumulate in cell vacuoles.

Chemical structure of flavonoidsFig. 1 Skeleton of DiphenylpropaneTheir basic structure is a skeleton of diphenylpropane, namely, two benzene rings (ring A and B, see figure) linked by a three carbon chain that forms a closed pyran ring (heterocyclic ring containing oxygen, the C ring) with benzenic A ring. Therefore, their structure is also referred to as C6-C3-C6.In most cases, B ring is attached to position 2 of C ring, but it can also bind in position 3 or 4; this, together with the structural features of the ring B and the patterns of glycosylation and hydroxylation of the three rings, makes the flavonoids one of the larger and more diversified groups of phytochemicals, so not only of polyphenols, in nature.Their biological activities, for example they are potent antioxidants, depend both on the structural characteristics and the pattern of glycosylation.Classification of flavonoidsFig. 2 Flavonoid SubgroupsThey can be subdivided into different subgroups depending on the carbon of the C ring on which B ring is attached, and the degree of unsaturation and oxidation of the C ring.Flavonoids in which B ring is linked in position 3 of the ring C are called isoflavones; those in which B ring is linked in position 4, neoflavonoids, while those in which the B ring is linked in position 2 can be further subdivided into several subgroups on the basis of the structural features of the C ring. These subgroup are: flavones, flavonols, flavanones, flavanonols, flavanols or catechins and anthocyanins.Finally, flavonoids with open C ring are called chalcones. FlavonesThey have a double bond between positions 2 and 3 and a ketone in position 4 of the C ring. Most flavones of vegetables and fruits has a hydroxyl group in position 5 of the A ring, while the hydroxylation in other positions, for the most part in position 7 of the A ring or 3 and 4 of the B ring may vary according to the taxonomic classification of the particular vegetable or fruit.Glycosylation occurs primarily on position 5 and 7, methylation and acylation on the hydroxyl groups of the B ring.Some flavones, such as nobiletin and tangeretin, are polymethoxylated.FlavonolsCompared to flavones, they have a hydroxyl group in position 3 of the C ring, which may also be glycosylated. Again, like flavones, flavonols are very diverse in methylation and hydroxylation patterns as well, and, considering the different glycosylation patterns, they are perhaps the most common and largest subgroup of flavonoids in fruits and vegetables. For example, quercetin is present in many plant foods. Flavanones Flavanones, also called dihydroflavones, have the C ring saturated; therefore, unlike flavones, the double bond between positions 2 and 3 is saturated and this is the only structural difference between the two subgroups of flavonoids.The flavanones can be multi-hydroxylated, and several hydroxyl groups can be glycosylated and/or methylated.Some have unique patterns of substitution, for example, furanoflavanones, prenylated flavanones, pyranoflavanones or benzylated flavanones, giving a great number of substituted derivatives.Over the past 15 years, the number of flavanones discovered is significantly increased. FlavanonolsFlavanonols, also called dihydroflavonols, are the 3-hydroxy derivatives of flavanones; they are an highly diversified and multisubstituted subgroup. IsoflavonesAs anticipated, isoflavones are a subgroup of flavonoids in which the B ring is attached to position 3 of the C ring. They have structural similarities to estrogens, such as estradiol, and for this reason they are also called phytoestrogens. NeoflavonoidsThey have the B ring attached to position 4 of the C ring. Flavanols or flavan-3-ols or catechinsFlavanols are also referred to flavan-3-ols as the hydroxyl group is almost always bound to position 3 of C ring; they are called catechins as well Unlike many flavonoids, there is no double bond between positions 2 and 3. Another distinctive features, e.g. compared to flavanonols, with which they share a hydroxyl group in position 3, is the lack of a carbonyl group, that is, a keto group, in position 4. This particular chemical structure allows flavanols to have two chiral centers in the molecule, on positions 2 and 3, then four possible diastereoisomers. Epicatechin is the isomer with the cis configuration and catechin is the one with the trans configuration. Each of these configurations has two stereoisomers, namely, (+)-epicatechin and (-)-epicatechin, (+)-catechin and (-)-catechin.(+)-Catechin and (-)-epicatechin are the two isomers most often present in edible plants. Another important feature of flavanols, particularly of catechin and epicatechin, is the ability to form polymers, called proanthocyanidins or condensed tannins. The name proanthocyanidins is due to the fact that an acid-catalyzed cleavage produces anthocyanidins.Proanthocyanidinstypically contain 2 to 60 monomers of flavanols.Monomeric and oligomeric flavanols(containing 2 to 7 monomers) are strong antioxidants. AnthocyanidinsChemically, anthocyanidins are flavylium cations and are generally present as chloride salts.They are the only group of flavonoids that gives plants colors (all other flavonoids are colorless).Anthocyanins are glycosides of anthocyanidins. Sugar units are bound mostly to position 3 of the C ring and they are often conjugated with phenolic acids, such as ferulic acid.The color of the anthocyanins depends on the pH and also by methylation or acylation at the hydroxyl groups on the A and B rings. ChalconesChalcones and dihydrochalcones are flavonoids with open structure; they are classified as flavonoids because they have similar synthetic pathways

Lipids: definition, classification and functionsWhat are lipids? High Fat/Oil FoodsLipids, together withcarbohydrates, proteins and nucleic acids, are one of the four major classes of biologically essential organic molecules found in all living organisms; their amounts and quality in diet are able to influence cell, tissue and body physiology.Unlikecarbohydrates, proteins and nucleic acids they arent polymers but small molecules, with a molecular weights that range between 100 and 5000, and also vary considerably in polarity, including hydrophobic molecules, like triglycerides or sterol esters, and others more water-soluble like phospholipids or very short-chain fatty acids, the latter completely miscible with water and insoluble in non polar solvents.The little or absent water-solubility of many of them means that they are subject to special treatments at all stages of their utilization, that is in the course of digestion, absorption, transport, storage and use.

Chimical structure of lipidsThere are eight general categories of lipids, but I will only go into seven(fatty acids, waxes, triacylglycerides, phospholipids, prostaglandins, steroids,and lipophilic vitamins)

Classification of lipidsThey may be classified based on their physical properties at room temperature (solid or liquid, respectively fats and oils), on polarity, or on their essentiality for humans, but the preferable classification is based on their structure.Based on structure, they can be classified in three major groups. Simple lipidsThey consist of two types of structural moieties.They include:glyceryl esters that is esters of glycerol and fatty acids: e.g. triacylglycerols, mono- and diacylglycerols;cholesteryl esters that is esters of cholesterol and fatty acids;waxes which are esters of long-chain alcohols and fatty acids, so including esters of vitamins A and D;ceramides that is amides of fatty acidswith long-chain di- or trihydroxy bases containing 1222 carbon atoms in the carbon chain: e.g. sphingosine.carbon chain: e.g. sphingosine. Complex lipidsThey consist of more than two types of structural moieties.They include:phospholipids that is glycerol esters of fatty acids;phosphoric acid, and other groups containing nitrogen;phosphatidic acid that is diacylglycerol esterified to phosphoric acid;phosphatidylcholine that is phosphatidic acid linked to choline, also called lecithin;phosphatidylethanolamine;phosphatidylserine;posphatidylinositol;phosphatidyl acylglycerol in which more than one glycerol molecule is esterified to phosphoric acid: e.g. cardiolipin and diphosphatidyl acylglycerol;glycoglycerolipids that is 1,2-diacylglycerol joined by a glycosidic linkage through position sn-3 with a carbohydrate moiety;gangliosides that is glycolipids that are structurally similar to ceramide polyhexoside and also contain 1-3 sialic acid residues; most contain an amino sugar in addition to the other sugars;sphingolipids, derivatives of ceramides;sphingomyelin that is ceramide phosphorylcholine;cerebroside: they are ceramide monohexoside that is ceramide linked to a single sugar moiety at the terminal hydroxyl group of the base)ceramide di- and polyhexoside that is linked respectively to a disaccharide or a tri- or oligosaccharide;cerebroside sulfate that is ceramide monohexoside esterified to a sulfate group. Derived lipidsThey occur as such or are released from the other two major groups because of hydrolysis that is are the building blocks for simple and complex lipids.They include:fatty acidsand alcohols;fat soluble vitamins A, D, E and K;hydrocarbons;sterols.Classification adapted from: Bloor W.R. Proc Soc Exp Biol Med, 17, 138, 1920; Christie W.W. in Lipid Analysis Pergamon Press, Oxford, 1982; Pomeranz Y. and Meloan C.L. in Food Analysis; Theory and Practice 4th ed., AVI, Westport, Connecticut, 1994; Akoh C.C. and Min D.B. Food lipids: chemistry, nutrition, and biotechnology 3th ed. 2008.Functions of lipids They are stored in adipose tissue (triglycerides) and are one of the major energy source. Lipids are the best energy source for humans since at a parity of weight they provide the major part of calories: ifcarbohydrates, on average, gives 4 kcal/g, as proteins, lipids provide, on average, 9 kcal/g. Moreover, they can be present in foods without there are also fiber or water (forpolysaccharides2 g water/g)allowing to contain a great quantity of energy in a little weight.Mostly of Nutrition Organizations recommend that lipids must contribute up to 30% (with saturated fatty acids only less than 10%) of the total daily energy intake. Some lipids are essential nutrients like fat-soluble vitamins A, (necessary for vision) and D (necessary for calciummetabolism), present in some fats and oils of animal origin, vitamin E (prevention of autoxidation of unsaturated lipids), present in vegetable oils, and vitamin K (normal clotting of blood) present in green leaves, essential fatty acids, in particularlinoleicand-linolenicacids, founders of the family ofomega-6andomega-3fatty acids respectively. During growth they are utilized as bricks for construction of biological membranes (phospholipids, cholesterol and glycolipids together with proteins), so contributing to construction of that barrier that separates intracellular environment from extracellular one and, inside cell, circumscribes organelles like mitochondria, Golgi apparatus or nucleus, and whose integrity is the basis of life itself; moreover they are also important for maintenance, physiochemical properties and repairing of cell membranes themselves. Many hormones are lipids: steroid hormones, like estrogens, androgens and cortisol, are formed from cholesterol (essential also during embryogenesis), prostaglandins, prostacyclin, leukotrienes, thromboxanes, and other compounds (all eicosanids) fromomega-3andomega-6polyunsaturated fatty acids with 20 carbon atoms. On plasmatic cell membranes they can act as receptors, antigens and membrane anchors for proteins and can modify the structure, and therefore the functionality, of membrane enzymes. Many lipids, like diacylglycerol, ceramides, sphingosine and platelet-activating factor act as regulators of intracellular processes. There are fat deposits not accessed during a fast, classified as structural fat, the function of which is to hold organs and nerves in the right position protecting them against traumatic injuries and shock; fat pads on the palms and buttocks protect the bones from mechanical pressure. A subcutaneous layer of fat is present in humans: it insulates the body reducing the loss of body heat and contributing to maintain body temperature. On epidermis they are involved in maintaining water barrier. They are electrical insulator of axon of neurons that are covered over and over again by plasmatic membranes of Swann cells, in peripheral nervous system, and of oligodendrocytes in central nervous system; these plasmatic membranes have a lipid content greater than that of the other cells. This lipoprotein coating is On digestive tract they facilitate the digestive process depressing gastric secretion, slowing gastric emptying and stimulating biliary and pancreatic flow. Bile salts (by-products of cholesterol) are natural detergents synthesized in the liver and secreted into bile. They solubilize phospholipids and cholesterol in the bile, permitting the secretion of cholesterol into the intestine (the excretion of both cholesterol and bile acids is the major way by which cholesterol is removed from the body). Bile salts also aid in the digestion and absorption of fat and soluble-fat vitamins in gut. In many animals, some lipids are secreted into external environment and act as pheromones that attract or repel other organisms. They affect the texture and flavor of food and so its palatability.Food manufacturers use fat for its textural properties, e.g. in baked goods fat increase the tenderness of the product. Chefs know that fat addiction add to the palatability of meal and increase satiety after a meal. Cancer What is cancer? Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. Cancer cells can spread to other parts of the body through the blood and lymph systems.Cancer is not just one disease but many diseases. There are more than 100 different types of cancer. Most cancers are named for the organ or type of cell in which they start - for example, cancer that begins in the colon is called colon cancer; cancer that begins in melanocytes of the skin is called melanomaOrigins of CancerAll cancers begin in cells, the body's basic unit of life. To understand cancer, it's helpful to know what happens when normal cells become cancer cells.The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die and are replaced with new cells.However, sometimes this orderly process goes wrong. The genetic material (DNA) of a cell can become damaged or changed, producing mutations that affect normal cell growth and division. When this happens, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called a tumor.

Cancer is not one disease. It is a group of more than 100 different and distinctive diseases. Cancer can involve any tissue of the body and have many different forms in each body area. Most cancers are named for the type of cell or organ in which they start. If a cancer spreads (metastasizes), the new tumor bears the same name as the original (primary) tumor.

SymptomsSigns and symptoms caused by cancer will vary depending on what part of the body is affected. Some general signs and symptoms associated with, but not specific to, cancer include: Fatigue Lump or area of thickening that can be felt under the skin Weight changes, including unintended loss or gain Skin changes, such as yellowing, darkening or redness of the skin, sores that won't heal, or changes to existing moles Changes in bowel or bladder habits Persistent cough Difficulty swallowing Hoarseness Persistent indigestion or discomfort after eating Persistent, unexplained muscle or joint pain Persistent, unexplained fevers or night sweatsHow Cancer is TreatedThe cancer treatment options your doctor recommends depends on the type and stage of cancer, possible side effects, and the patient's preferences and overall health. In cancer care, different types of doctors often work together to create a patient's overall treatment plan that combines different types of treatments.all the main cancer treatments: surgery, radiotherapy, chemotherapy, hormone therapy biological therapies, bisphosphonates bone marrow and stem cell transplants. There is also information about complementary and alternative therapies.

Tumor Definition of tumor: An abnormal mass of tissue. Tumors are a classic sign of inflammation, and can be benign or malignant (cancerous). There are dozens of different types of tumors. Their names usually reflect the kind of tissue they arise in, and may also tell you something about their shape or how they grow. For example, a medulloblastoma is a tumor that arises from embryonic cells (a blastoma) in the inner part of the brain (the medulla). Diagnosis depends on the type and location of the tumor. Tumor marker tests and imaging may be used; some tumors can be seen (for example, tumors on the exterior of the skin) or felt (palpated with the hands).Cancer stem cells may play a major role in tumor growth, three studies published in the journals Nature and Science revealed in August 2012. Scientists believe cancer might have its own stem cells that impact on the regrowth of tumors. They added that if further studies confirm their findings, the way we treat cancerous tumors may change dramatically.What is a benign tumor?A benign tumor (benign neoplasm) cannot metastasize - it cannot spread. Examples include uterine fibroids and moles. "Benign" means it is non-progressive, it remains as it is.

Most benign tumors are not harmful to human health. Even though they are not cancerous, some may press against nerves or blood vessels and cause pain or other negative effects. Benign tumors of endocrine tissues may result in the excessive production of some hormones.

Examples of benign tumors include: Adenomas - tumors that arise from glandular epithelial tissue - epithelial tissue is the thin membrane that covers glands, organs and other structures in the body. A polyp in the colon is a type of adenoma. Other examples include pituitary adenoma, adrenocortical adenoma, basal cell adenoma, bile duct adenoma, chromophobe adenoma, follicular adenoma, hepatocellular adenoma, and nipple adenoma (there are many more).

Although adenomas are not cancerous, they can change and become so; then they are called adenocarcinomas.

Fibroids (fibromas) - benign tumors that grow on fibrous or connective tissue of any organ in the body. Uterine fibroids are common. Uterine fibroids can cause vaginal bleeding, pelvic pain or discomfort, and urinary incontinence.

The fibroma durum (hard fibroma) is made up of many fibers and few cells. The fibroma molle (soft fibroma) is made up of several loosely connected cells and less fibroid tissue. Soft fibroma is usually found in the armpits, groin, neck and eyelids.

There are many types of fibromas, such as angiofibroma, cystic fibroma (fibroma cysticum), myxofibroma (fibroma myxomatodes), nonossifying fibroma, ossifying fibroma, cemento-ossifying fibroma, pleomorphic fibroma, fibroma of tendon sheath nuchal fibroma, chondromyxoid fibroma, desmoplasmic fibroma, collagenous fibroma, and perifollicular fibroma.

Some fibromas can cause symptoms and may require surgical removal. Rarely, fibroids can change and eventually become cancerous, they are then called fibrosarcomas.

Hemangiomas - benign tumors which consists of a collection of too many blood cells. They can sometimes be seen on the surface of the skin and are colloquially called strawberry marks. The majority of hemangiomas appear at birth and gradually go away after some months or years.

Hemangiomas do not usually require any treatment. If they affect the patient's ability to eat, hear or see, the doctor may recommend treatment with corticosteroids. If the patient is over 10 years of age, they are more commonly removed today using laser surgery. Lipomas - the most common form of soft-tissue tumor. Lipomas consist of adipose tissue (fat cells). Most of them are very small, painless, soft to the touch, and generally movable. They are more common among people aged 40+ years. Experts disagree on whether lipomas can change and become cancerous (malignant).

There are many kinds of lipomas, such as angiolipoleiomyoma, angiolipoma, chondroid lipoma, corpus callosum lipoma, hibernoma, intradermal spindle cell lipoma, neural fibrolipoma, pleomorphic lipomas, and superficial subcutaneous lipoma (the most common type, found just below the skin's surface).What is a premalignant tumor?A premalignant or precancerous tumor is one that is not yet malignant, but is about to become so.

Examples of premalignant growths include: Actinic keratosis - also known as senile keratosis or solar keratosis is a premalignant growth consisting of crusty, scaly and thick patches of skin. Fair-skinned people are more susceptible to these types of growths, especially those who are exposed to sunlight (it is linked to solar damage).

Actinic keratoses are seen as potentially premalignant because a number of them progress to squamous cell carcinoma. Doctors usually recommend treating them because of this. There is a 20% risk that untreated lesions eventually become cancerous. Continuous sun exposure increases the risk of malignancy.

Dysplasia of the cervix - the normal cells lining the cervix of the uterus change. The growth can be premalignant, a prelude to cervical cancer. Cervical dysplasia is diagnosed with a PAP smear. According to the National Institutes of Health, USA, about 5% of PAP smears detect the presence of cervical dysplasia. They are more common in women aged 25 to 35. They may be removed with Cryotherapy (freezing), or conization (the cone of tissue from the cervix is removed).

Metaplasia of the lung - the growths occur in the bronchi, tubes that carry air from the windpipe into the lung. The bronchi are lined with glandular cells, which can change and become squamous cells. Metaplasia of the lung is most commonly caused by smoking.

Leukoplakia - thick, white patches form on the gums, bottom of the mouth, insides of the cheeks, and less commonly on the tongue. They cannot be scraped off easily. Experts believe tobacco smoking and/or chewing is the main cause. Although Leukoplakia is rarely dangerous, a small percentage are premalignant and can eventually become cancerous. Many mouth cancers occur next to areas of leukoplakia.

If smokers quit, the condition usually clears up. Quitting both alcohol and tobacco together has better results. The patches can be removed using laser, a scalpel or a cold probe that freezes the cancer cells (cryoprobe).What is a malignant tumor?Malignant tumors are cancerous tumors, they tend to become progressively worse, and can potentially result in death. Unlike benign tumors, malignant ones grow fast, they are ambitious, they seek out new territory, and they spread (metastasize).

The abnormal cells that form a malignant tumor multiply at a faster rate. Experts say that there is no clear dividing line between cancerous, precancerous and non-cancerous tumors - sometimes determining which is which may be arbitrary, especially if the tumor is in the middle of the spectrum. Some benign tumors eventually become premalignant, and then malignant.

Metastasis - malignant tumors invade nearby cells, and then the cells near those, and spread. Some cells can break off from the tumor and spread to various parts of the body through the bloodstream or the lymphatic system, and establish themselves anywhere in the body, and form new malignant tumors. Metastasis is the process by which cancer cells spread from their primary site to distant locations in the human body. For example, a patient may have started off with melanoma (skin cancer) which metastasized in their brain.The cancer cells that metastasize are the same as the original ones. If a lung cancer spreads to the liver, those cancer cells that grow in the liver are lung cancer cells which have acquired the ability to invade other organs.

There are different types of tumors, which are made up of specific types of cancer cells: Carcinoma - these tumors are derived from the skin or tissues that line body organs (epithelial cells). Carcinomas can be, for example, of the stomach, prostate, pancreas, lung, liver, colon or breast. Many of the most common tumors are of this type, especially among older patients.

Sarcoma - these are tumors that start off in connective tissue, such as cartilage, bones, fat and nerves. They originate in the mesenchymal cells outside the bone marrow. The majority of sarcoma tumors are malignant. They are called after the cell, tissue or structure they arise from, for example fibrosarcoma, liposarcoma, angiosarcoma, chondrosarcoma, and osteosarcoma. Lymphoma/Leukemia - cancer arises from the blood forming (hematopoietic) cells that originate in the marrow and generally mature in the blood or lymph nodes. Leukemia accounts for 30% of childhood cancers. Leukemia is thought to be the only cancer where tumors are not formed.

Germ cell tumor - these are tumors that arise from a germ cell, pluripotent cells (cells than can turn into any kind of cell). Germ cell tumors most commonly present in the ovary (dysgerminoma) or testicle (seminoma). The majority of testicular tumors are germ cell ones. Less commonly, germ cell tumors may also appear in the brain, abdomen or chest.

Blastoma - tumors derived from embryonic tissue or immature "precursor" cells. These types of tumors are more common in children than adults. "Blastoma" is often the root word used in longer ones that describe tumors, for example, medulloblastoma and glioblastoma are kinds of brain tumors, retinoblastoma is a tumor in the retina of the eye, osteoblastoma is a type of bone tumor, while a neuroblastoma is a tumor found in children of neural origin.What is a biopsy?To decide whether a tumor is malignant or not, a sample must be taken by a surgeon or an interventional radiologist and sent to the laboratory and examined under a microscope by a pathologist - the sample is called a biopsy. There are three different types of biopsies: Excisional biopsy - the entire lump or suspicious area is surgically removed.

When the specimen plus some surrounding uninvolved tissue is sent to the lab, the pathologist determines the extent of surgical margins around it to see whether the cancer spread beyond the area biopsied. Clear margins, also known as negative margins means that none of the tumor has spread beyond the edges of the biopsied specimen. Positive margins means the tumor has grown beyond the biopsied specimen. Sometimes a wider excision may be needed if the diagnosis is uncertain. Incisional (core) biopsy - a sample is surgically removed from the tumor

Needle aspiration biopsy - fluid or a sample of tissue is removed with a needle.

CELL:Definition: is the basic structural, functional, and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology.Cells consist of a protoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. Organisms can be classified as unicellular (consisting of a single cell; including most bacteria) or multicellular (including plants and animals). While the number of cells in plants and animals varies from species to species, humans contain about 100 trillion (1014) cells.] Most plant and animal cells are visible only under the microscope, with dimensions between 1 and 100micrometresThe cell was discovered by Robert Hooke in 1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.

Healty cellA healthy cell does not turn into a cancer cell overnight. Its behaviour gradually changes, a result of damage to between three and seven of the hundreds of genes that control cell growth, division and life span. First, the cell starts to grow and multiply. Over time, more changes may take place. The cell and its descendants may eventually become immortal, escape destruction by the body's defences, develop their own blood supply and invade the rest of body.

Unhealty cell:

Shapes of Healthy and Unhealthy Cells What is the basic difference between a healthy cell and an unhealthy cell? A healthy cell has a clean surface and innards. It produces clean energy for its functions and efficiently cleanses itself of waste. An unhealthy cell is swollen and its surface and innards are smeared with toxic materials. It cannot breathe well, produce clean energy, or rid itself of toxins. Near their death, diseased cells somtimes shrink. A healthy cell has a sharp outline (cell membrane) and its internal structures can be seen clearly with a microscope. An unhealthy cell has a fuzzy cell membrane and its innards are swollen and irregularly shaped.