vaccine

A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease.

Vaccines can be prophylactic (e.g. to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).

The term "vaccine" derives from Edward Jenner's 1796 use of cowpox (Latin variolæ vaccinæ, adapted from the Latin vaccīn-us, from vacca cow), which, when administered to humans, provided them protection against smallpox.

History

The earliest vaccines were based on the concept of variolation originating in China, in which a person is deliberately infected with a weak form of smallpox as a form of inoculation. Jenner realized that milkmaids who had contact with cowpox did not get smallpox. The process of distributing and administrating vaccines is thus referred to as "vaccination". Jenner's work was continued by Louis Pasteur and others in the 19th century. Since vaccination against smallpox was much safer than smallpox inoculation, the latter fell into disuse and was eventually banned in England in 1849.

The 19th and 20th centuries saw the introduction of several successful vaccines against a number of infectious diseases. These included bacterial and viral diseases, but not (to date) any parasitic diseases.

Types

Avian Flu vaccine development by reverse genetics techniques.

Vaccines may be dead or inactivated organisms or purified products derived from them.

There are four types of traditional vaccines:^[1]

• Vaccines containing killed microorganisms - these are previously virulent micro-organisms which have been killed with chemicals or heat. Examples are vaccines against flu, cholera, bubonic plague, and hepatitis A.
• Vaccines containing live, attenuated virus microorganisms - these are live micro-organisms that have been cultivated under conditions that disable their virulent properties or which use closely-related but less dangerous organisms to produce a broad immune response. They typically provoke more durable immunological responses and are the preferred type for healthy adults. Examples include yellow fever, measles, rubella, and mumps. The live tuberculosis vaccine is not the contagious strain, but a related strain called "BCG"; it is used in the United States very infrequently.
• Toxoids - these are inactivated toxic compounds in cases where these (rather than the micro-organism itself) cause illness. Examples of toxoid-based vaccines include tetanus and diphtheria. Not all toxoids are for micro-organisms; for example, Crotalis atrox toxoid is used to vaccinate dogs against rattlesnake bites.
• Subunit - rather than introducing an inactivated or attenuated micro-organism to an immune system (which would constitute a "whole-agent" vaccine), a fragment of it can create an immune response. Characteristic examples include the subunit vaccine against HBV that is composed of only the surface proteins of the virus (produced in yeast) and the virus-like particle (VLP) vaccine against human papillomavirus (HPV) that is composed of the viral major capsid protein.

A number of innovative vaccines are also in development and in use:

• Conjugate - certain bacteria have polysaccharide outer coats that are poorly immunogenic. By linking these outer coats to proteins (e.g. toxins), the immune system can be led to recognize the polysaccharide as if it were a protein antigen. This approach is used in the Haemophilus influenzae type B vaccine.
• Recombinant Vector - by combining the physiology of one micro-organism and the DNA of the other, immunity can be created against diseases that have complex infection processes
• DNA vaccination - in recent years a new type of vaccine, created from an infectious agent's DNA called DNA vaccination, has been developed. It works by insertion (and expression, triggering immune system recognition) into human or animal cells, of viral or bacterial DNA. Some cells of the immune system that recognize the proteins expressed will mount an attack against these proteins and cells expressing them. Because these cells live for a very long time, if the pathogen that normally expresses these proteins is encountered at a later time, they will be attacked instantly by the immune system. One advantage of DNA vaccines is that they are very easy to produce and store. As of 2006, DNA vaccination is still experimental.

While most vaccines are created using inactivated or attenuated compounds from micro-organisms, synthetic vaccines are composed mainly or wholly of synthetic peptides, carbohydrates or antigens.

Vaccines may be monovalent (also called univalent) or multivalent (also called polyvalent). A monovalent vaccine is designed to immunize against a single antigen or single microorganism.^[2] A multivalent or polyvalent vaccine is designed to immunize against two or more strains of the same microorganism, or against two or more microorganisms.^[3]

ORYZA

Scientific classification
Kingdom:Plantae
(unranked):Angiosperms
(unranked):Monocots
(unranked):Commelinids
Order:Poales
Family:Poaceae
Subfamily:Bambusoideae
Tribe:Oryzeae
Genus:OryzaL.

Oryza is a genus of 7-20 species of grasses in the tribe Oryzeae, within the subfamily Bambusoideae. native to tropical and subtropical regions of Asia and Africa. They are tall wetland grasses, growing to 1-2 m tall; the genus includes both annual and perennial species.
Oryza is situated within the tribe Oryzeae, which is characterized morphologically by its single flowered spikelets whose glumes are almost completely suppressed. In Oryza, two sterile lemma simulate glumes. The tribe Oryzeae is within the subfamily Bambusoideae, a group of Poaceae tribes with certain features of internal leaf anatomy in common. The most distinctive leaf character of this subfamily is their arm cells and fusoid cells found in their leafs. The Bambusoideae are in the family Poaceae, as they all have fibrous root systems, cylindrical stems, sheathing leaves with parallel veined blades, and inflorescences with spikelets. [1]
While USDA plants lists only 7 species, others have identified up to 17, including sativa, barthii, glaberrima, meridionalis, nivara, rufipogon, punctata, latifolia, alta, grandiglumis, eichingeri, officinalis, rhisomatis, minuta, australiensis, granulata, meyeriana, and brachyantha. One species, Rice (O. sativa), provides twenty percent of global grain and is a food crop of major global importance. The many species mentioned above are divided into two subgroups within the genus
Selected species
Oryza barthii
Oryza glaberrima
Oryza latifolia
Oryza longistaminata
Oryza punctata
Oryza rufipogon
Oryza sativa

DNA structure

DNA structure
Main article: DNA

The chemical structure of DNA.
DNA usually exists in a double-stranded structure, with both strands coiled together to form the characteristic double-helix. Each single strand of DNA is a chain of four types of nucleotide: adenine, cytosine, guanine, and thymine. A nucleotide consists of a phosphate and a deoxyribose sugar forming the backbone of the DNA double helix plus a base that points inwards. Nucleotides are matched between strands through hydrogen bonds to form base pairs. Adenine pairs with thymine and cytosine pairs with guanine.
The physical pairing of bases in DNA means that the information contained within each strand is redundant. The nucleotides on a single strand can be used to reconstruct nucleotides on a newly synthesized partner strand.
DNA strands have a directionality, and the different ends of a single strand are called the "3' end" and the "5' end" (these refer to the carbon atom in ribose that the next phosphate in the chain attaches to). In addition to being complementary, the two strands of DNA are antiparallel: they are orientated in opposite directions. This directionality has consequences in DNA synthesis, because DNA polymerase can only synthesize DNA in one direction by adding nucleotides to the 3' end of a DNA strand

DNA polymerase
Main article: DNA polymerase

DNA polymerase adds nucleotides to the 3' end of a strand of DNA. If a mismatch is accidentally incorporated, the polymerase is inhibited from further extension. Proofreading removes the mismatched nucleotide and extension continues.
DNA polymerases are a family of enzymes critical for all forms of DNA replication.[4] A DNA polymerase synthesizes a new strand of DNA by extending the 3' end of an existing nucleotide chain, adding new nucleotides matched to the template strand one at a time. Some DNA polymerases may also have some proofreading ability, removing nucleotides from the end of a strand in order to remove any mismatched bases. DNA polymerases are generally extremely accurate, making less than one error for every 109 nucleotides added.
The energy for the process of DNA polymerization comes from the two additional phosphates attached to each of the unincorporated nucleotides. These free nucleotides, also known as nucleoside triphosphates, contain a total of three phosphates. When a nucleotide is being added to a growing DNA strand, two of the phosphates are removed and the energy produced is used to attach the remaining phosphate to the growing chain. The energetics of this process may also explain the directionality of synthesis - if DNA were synthesized in the 3' to 5' direction, the energy for the process would come from the 5' end of the growing strand rather than from free nucleotides. During proofreading, if the 5' nucleotide needed to be removed this triphosphate end would be lost, losing the energy source required to add a new nucleotide to the end.
DNA polymerase can only extend an existing DNA strand paired with a template strand, it cannot begin the synthesis of a new strand. To do this a short fragment of DNA or RNA, called a primer, must be created and paired with the template strand before DNA polymerase can synthesize new DNA.

[DNA replication within the cell
Main articles: Prokaryotic DNA replication and Eukaryotic DNA replication

Origins of replication
For a cell to divide, it must first replicate itself into newer ones DNA.

[5] This process is initiated at particular points within the DNA, known as "origins", which are targeted by proteins that separate the two strands and initiate DNA synthesis.

[3] Origins contain DNA sequences recognized by replication initiator proteins (eg. dnaA in E coli' and the Origin Recognition Complex in yeast).

[6] These initiator proteins recruit other proteins to separate the two strands and initiate replication forks.
Initiator proteins recruit other proteins to separate the DNA strands at the origin, forming a bubble. Origins tend to be "AT-rich" (rich in adenine and thymine bases) to assist this process because A-T base pairs have two hydrogen bonds (rather than the three formed in a C-G pair)—strands rich in these nucleotides are generally easier to separate.

[7] Once strands are separated, RNA primers are created on the template strands and DNA polymerase extends these to create newly synthesized DNA.
As DNA synthesis continues, the original DNA strands continue to unwind on each side of the bubble, forming replication forks. In bacteria, which have a single origin of replication on their circular chromosome, this process eventually creates a "theta structure" (resembling the Greek letter theta: θ).

In contrast, eukaryotes have longer linear chromosomes and initiate replication at multiple origins within these.

photorespiration

The details of photorespiration
The uptake of O2 by RUBISCO forms:
the 3-carbon molecule 3-phosphoglyceric acid — just as in the Calvin cycle
the 2-carbon molecule glycolate.
The glycolate enters peroxisomes where it uses O2 to form intermediates that
enter mitochondria where they are broken down to CO2. So this process uses O2 and liberates CO2 as cellular respiration does which is why it is called photorespiration.
It undoes the good anabolic work of photosynthesis, reducing the net productivity of the plant. For this reason, much effort — so far largely unsuccessful — has gone into attempts to alter crop plants so that they carry on less photorespiration.
The problem may solve itself. If atmospheric CO2 concentrations continue to rise, perhaps this will enhance the net productivity of the world's crops by reducing losses to photorespiration.

C4 Plants
Over 8000 species of angiosperms, scattered among 18 different families, have developed adaptations which minimize the losses to photorespiration. They all use a supplementary method of CO2 uptake which forms a 4-carbon molecule instead of the two 3-carbon molecules of the Calvin cycle. Hence these plants are called C4 plants. (Plants that have only the Calvin cycle are thus C3 plants.)
Some C4 plants — called CAM plants — separate their C3 and C4 cycles by time. CAM plants are discussed below.
Other C4 plants have structural changes in their leaf anatomy so that
their C4 and C3 pathways are separated in different parts of the leaf with
RUBISCO sequestered where the CO2 level is high; the O2 level low.These adaptations are described now.
The details of the C4 cycle
After entering through stomata, CO2 diffuses into a mesophyll cell.
Being close to the leaf surface, these cells are exposed to high levels of O2, but
have no RUBISCO so cannot start photorespiration (nor the dark reactions of the Calvin cycle).
Instead the CO2 is inserted into a 3-carbon compound (C3) called phosphoenolpyruvic acid (PEP) forming
the 4-carbon compound oxaloacetic acid (C4).
Oxaloacetic acid is converted into malic acid or aspartic acid (both have 4 carbons), which is
transported (by plasmodesmata) into a bundle sheath cell. Bundle sheath cells
are deep in the leaf so atmospheric oxygen cannot diffuse easily to them;
often have thylakoids with reduced photosystem II complexes (the one that produces O2).
Both of these features keep oxygen levels low.
Here the 4-carbon compound is broken down into
carbon dioxide, which enters the Calvin cycle to form sugars and starch.
pyruvic acid (C3), which is transported back to a mesophyll cell where it is converted back into PEP.These C4 plants are well adapted to (and likely to be found in) habitats with
high daytime temperatures
intense sunlight. Some examples:
crabgrass
corn (maize)
sugarcane
sorghum
C4 cells in C3 plantsThe ability to use the C4 pathway has evolved repeatedly in different families of angiosperms. Perhaps the potential is in them all.
A report in the 24 January 2002 issue of Nature (by Julian M. Hibbard and W. Paul Quick) describes the discovery that tobacco, a C3 plant, has cells capable of fixing carbon dioxide by the C4 path. These cells are clustered around the veins (containing xylem and phloem) of the stems and also in the petioles of the leaves. In this location, they are far removed from the stomata that could provide atmospheric CO2. Instead, they get their CO2 and/or the 4-carbon malic acid in the sap that has been brought up in the xylem from the roots.
If this turns out to be true of many C3 plants, it would explain why it has been so easy for C4 plants to evolve from C3 ancestors.
CAM PlantsThese are also C4 plants but instead of segregating the C4 and C3 pathways in different parts of the leaf, they separate them in time instead. (CAM stands for crassulacean acid metabolism because it was first studied in members of the plant family Crassulaceae.)
At night,
CAM plants take in CO2 through their open stomata (they tend to have reduced numbers of them).
The CO2 joins with PEP to form the 4-carbon oxaloacetic acid.
This is converted to 4-carbon malic acid that accumulates during the night in the central vacuole of the cells.In the morning,
the stomata close (thus conserving moisture as well as reducing the inward diffusion of oxygen).
The accumulated malic acid leaves the vacuole and is broken down to release CO2.
The CO2 is taken up into the Calvin (C3) cycle.These adaptations also enable their owners to thrive in conditions of
high daytime temperatures
intense sunlight
low soil moisture.Some examples of CAM plants:
cacti
Bryophyllum
the pineapple and all epiphytic bromeliads
sedums
the "ice plant" that grows in sandy parts of the scrub forest biome

MELANIN IN HUMANS

In humans, melanin is the primary determinant of human skin color and also found in hair, the pigmented tissue underlying the iris, the medulla and zona reticularis of the adrenal gland, the stria vascularis of the inner ear, and in pigment-bearing neurons within areas of the brain stem, such as the locus ceruleus and the substantia nigra.
Dermal melanin is produced by melanocytes, which are found in the stratum basale of the epidermis. Although human beings generally possess a similar concentration of melanocytes in their skin, the melanocytes in some individuals and ethnic groups more frequently or less frequently express the melanin-producing genes, thereby conferring a greater or lesser concentration of skin melanin. Some individual animals and humans have very little or no melanin in their bodies, a condition known as albinism.
Because melanin is an aggregate of smaller component molecules, there are a number of different types of melanin with differing proportions and bonding patterns of these component molecules. Both pheomelanin and eumelanin are found in human skin and hair, but eumelanin is the most abundant melanin in humans, as well as the form most likely to be deficient in albinism.
Eumelanin polymers have long been thought to comprise numerous cross-linked 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) polymers; recent research into the electrical properties of eumelanin, however, has indicated that it may consist of more basic oligomers adhering to one another by some other mechanism. Thus, the precise nature of eumelanin's molecular structure is once again the object of study.[citation needed] Eumelanin is found in hair and skin, and colors hair grey, black, yellow, and brown. In humans, it is more abundant in peoples with dark skin. There are two different types of eumelanin, which are distinguished from each other by their pattern of polymer bonds. The two types are black eumelanin and brown eumelanin, with black melanin being darker than brown. Black eumelanin is in mostly non-Europeans and aged Europeans, while brown eumelanin is in mostly young Europeans. A small amount of black eumelanin in the absence of other pigments causes grey hair. A small amount of brown eumelanin in the absence of other pigments causes yellow (blond) color hair.
Pheomelanin is also found in hair and skin and is both in lighter skinned humans and darker skinned humans. In general women have more pheomelanin than men, and thus women's skin is generally redder than men's. Pheomelanin imparts a pink to red hue and, thus, is found in particularly large quantities in red hair. Pheomelanin is particularly concentrated in the lips, nipples, glans of the penis, and vagina.[4] Pheomelanin also may become carcinogenic when exposed to the ultraviolet rays of the sun. Chemically, pheomelanin differs from eumelanin in that its oligomer structure incorporates benzothiazine units which are produced instead of DHI and DHICA when the amino acid L-cysteine is present.
Neuromelanin is the dark pigment present in pigment bearing neurons of four deep brain nuclei: the substantia nigra (in Latin, literally "black substance") - Pars Compacta part, the locus ceruleus ("blue spot"), the dorsal motor nucleus of the vagus nerve (cranial nerve X), and the median raphe nucleus of the pons. Both the substantia nigra and locus ceruleus can be easily identified grossly at the time of autopsy due to their dark pigmentation. In humans, these nuclei are not pigmented at the time of birth, but develop pigmentation during maturation to adulthood. Although the functional nature of neuromelanin is unknown in the brain, it may be a byproduct of the synthesis of monoamine neurotransmitters for which the pigmented neurons are the only source. The loss of pigmented neurons from specific nuclei is seen in a variety of neurodegenerative diseases. In Parkinson's disease there is massive loss of dopamine producing pigmented neurons in the substantia nigra. A common finding in advanced Alzheimer's disease is almost complete loss of the norepinephrine producing pigmented neurons of the locus ceruleus. Neuromelanin has been detected in primates and in carnivores such as cats and dogs.LA

SKINPIGMENTS

INTRODUCTION

Various shades and colors of human skin are created by the brown pigment, melanin. Without melanin, the skin would be pale white with varying shades of pink caused by the blood flowing through it. Fair-skinned people produce very little melanin; darker-skinned people produce moderate amounts; and very dark skinned people produce a great deal. People with albinism have no melanin.
Melanin is produced by special cells (melanocytes) that are interspersed among the other cells in the top layer of the skin, the epidermis. After melanin is produced, it spreads into other nearby skin cells.
When exposed to sunlight, melanocytes produce increased amounts of melanin, causing the skin to darken, or tan. In some fair-skinned people, certain melanocytes produce more melanin than others in response to sunlight. This uneven melanin production results in spots of pigmentation known as freckles. A tendency to freckles runs in families. Increased amounts of melanin can also occur in response to hormonal changes, such as those that may take place in Addison's disease, in pregnancy, or with oral contraceptive use. Some cases of skin darkening, however, are not related to increased melanin at all, but rather to abnormal pigments that make their way into the skin. Diseases such as hemochromatosis or hemosiderosis or some drugs that are applied to the skin, swallowed, or injected can cause skin darkening. A buildup of bilirubin (the main pigment in bile) causes the skin to turn yellow (jaundice).
An abnormally low amount of melanin (hypopigmentation) may affect large areas of the body or small patches. Decreased melanin usually results from a previous injury to the skin such as a blister, ulcer, burn, or skin infection. Sometimes pigment loss results from an inflammatory condition of the skin or, in rare instances, is hereditary. A common skin infection, tinea versicolor BACTIRIAL SKIN DISORDERS

The skin provides a remarkably good barrier against bacterial infections. Although many bacteria come in contact with or reside on the skin, they are normally unable to establish an infection. When bacterial skin infections do occur, they can range in size from a tiny spot to the entire body surface. They can range in seriousness as well, from harmless to life threatening.
Many types of bacteria can infect the skin. The most common are Staphylococcus and Streptococcus. Skin infections caused by less common bacteria may develop in people while hospitalized or living in a nursing home, while gardening, or while swimming in a pond, lake, or ocean.
Some people are at particular risk of contracting skin infections. For example, people with diabetes are likely to have poor blood flow, especially to the hands and feet, and the high levels of sugar in their blood decrease the ability of white blood cells to fight infections. People with human immunodeficiency virus (HIV) or AIDS or other immune disorders and those undergoing chemotherapy are at higher risk as well, because they have a weakened immune system. Skin that is inflamed or damaged by sunburn, scratching, or other trauma is more likely to be infected. In fact, any break in the skin predisposes a person to infection.
Prevention involves keeping the skin undamaged and clean. When the skin is cut or scraped, the injury should be washed with soap and water and covered with a sterile bandage. Antibiotic creams and ointments may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. If an infection develops, small areas may be treated with antibiotic creams. Larger areas require antibiotics taken by mouth or given by injection. Abscesses (pus-filled pockets) should be cut open by the doctor and allowed to drain, and any dead tissue must be surgically removed.

major classes of peptides;

Here are the major classes of peptides, according to how they are produced:
Ribosomal peptides
Are synthesized by translation of mRNA. They are often subjected to proteolysis to generate the mature form. These function, typically in higher organisms, as hormones and signaling molecules. Some organisms produce peptides as antibiotics, such as microcins.

[1] Since they are translated, the amino acid residues involved are restricted to those utilized by the ribosome. However, these peptides frequently have posttranslational modifications, such as phosphorylation, hydroxylation, sulfonation, palmitylation, glycosylation and disulfide formation. In general, they are linear, although lariat structures have been observed.

[2] More exotic manipulations do occur, such as racemization of L-amino acids to D-amino acids in platypus venom

.[3]
Nonribosomal peptides
These peptides are assembled by enzymes that are specific to each peptide, rather than by the ribosome. The most common non-ribosomal peptide is glutathione, which is a component of the antioxidant defenses of most aerobic organisms.[4] Other nonribosomal peptides are most common in unicellular organisms, plants, and fungi and are synthesized by modular enzyme complexes called nonribosomal peptide synthetases.[5] These complexes are often laid out in a similar fashion, and they can contain many different modules to perform a diverse set of chemical manipulations on the developing product.[6] These peptides are often cyclic and can have highly-complex cyclic structures, although linear nonribosomal peptides are also common. Since the system is closely related to the machinery for building fatty acids and polyketides, hybrid compounds are often found. Oxazoles, thiazoles often indicate that the compound was synthesized in this fashion.[7]
Peptones
See also Tryptone
Are derived from animal milk or meat digested by proteolytic digestion. In addition to containing small peptides, the resulting spray-dried material includes fats, metals, salts, vitamins and many other biological compounds. Peptone is used in nutrient media for growing bacteria and fungi.[8]
Peptide Fragments
Refer to fragments of proteins that are used to identify or quantify the source protein.[9] Often these are the products of enzymatic degradation performed in the laboratory on a controlled sample, but can also be forensic or paleontological samples which have been degraded by natural effects.[10][11]

Peptides in molecular biology
Peptides have received prominence in molecular biology in recent times for several reasons. The first and most important is that peptides allow the creation of peptide antibodies in animals without the need to purify the protein of interest.[12] This involves synthesizing antigenic peptides of sections of the protein of interest. These will then be used to make antibodies in a rabbit or mouse against the protein.
Another reason is that peptides have become instrumental in mass spectrometry, allowing the identification of proteins of interest based on peptide masses and sequence. In this case the peptides are most often generated by in-gel digestion after electrophoretic separation of the proteins.
Peptides have recently been used in the study of protein structure and function. For example, synthetic peptides can be used as probes to see where protein-peptide interactions occur.
Inhibitory peptides are also used in clinical research to examine the effects of peptides on the inhibition of cancer proteins and other diseases.

Well-known peptide families in humans
The peptide families in this section are all ribosomal peptides, usually with hormonal activity. All of these peptides are synthesized by cells as longer "propeptides" or "proproteins" and truncated prior to exiting the cell. They are released into the bloodstream where they perform their signalling functions.

The Tachykinin peptides
Substance P
Kassinin
Neurokinin A
Eledoisin
Neurokinin B

Vasoactive intestinal peptides
VIP (Vasoactive Intestinal Peptide; PHM27)
PACAP Pituitary Adenylate Cyclase Activating Peptide
Peptide PHI 27 (Peptide Histidine Isoleucine 27)
GHRH 1-24 (Growth Hormone Releasing Hormone 1-24)
Glucagon
Secretin

Pancreatic polypeptide-related peptides
NPY
PYY (Peptide YY)
APP (Avian Pancreatic Polypeptide)
PPY Pancreatic PolYpeptide

Opioid peptides
Proopiomelanocortin (POMC) peptides
Enkephalin pentapeptides
Prodynorphin peptides

Calcitonin peptides
Calcitonin
Amylin
AGG01

Other peptides
B-type Natriuretic Peptide (BNP) - produced in myocardium & useful in medical diagnosis

Notes on terminology
A polypeptide is a single linear chain of amino acids.
A protein is one or more polypeptides more than about 50 amino acids long.
An oligopeptide or (simply) a peptide is a polypeptide less than 30-50 amino acids long.
A dipeptide has two amino acids.
A tripeptide has three amino acids.
A pentapeptide has five amino acids.
An octapeptide has eight amino acids. (e.g., angiotensin II.
A nonapeptide has nine amino acids (e.g., oxytocin).
A decapeptide has ten amino acids (e.g., gonadotropin-releasing hormone & angotensin I).
A neuropeptide is a peptide that is active in association with neural tissue.
A peptide hormone is a peptide that acts as a hormone.

See also
Peptidomimetics (such as peptoids and β-peptides) to peptides, but with different properties.
bis-peptide
Peptide synthesis
Translation
Ribosome
Argireline

peptides

Ribosomal peptides
Are synthesized by translation of mRNA. They are often subjected to proteolysis to generate the mature form. These function, typically in higher organisms, as hormones and signaling molecules. Some organisms produce peptides as antibiotics, such as microcins.[1] Since they are translated, the amino acid residues involved are restricted to those utilized by the ribosome. However, these peptides frequently have posttranslational modifications, such as phosphorylation, hydroxylation, sulfonation, palmitylation, glycosylation and disulfide formation. In general, they are linear, although lariat structures have been observed.[2] More exotic manipulations do occur, such as racemization of L-amino acids to D-amino acids in platypus venom.[3]
Nonribosomal peptides
These peptides are assembled by enzymes that are specific to each peptide, rather than by the ribosome. The most common non-ribosomal peptide is glutathione, which is a component of the antioxidant defenses of most aerobic organisms.[4] Other nonribosomal peptides are most common in unicellular organisms, plants, and fungi and are synthesized by modular enzyme complexes called nonribosomal peptide synthetases.[5] These complexes are often laid out in a similar fashion, and they can contain many different modules to perform a diverse set of chemical manipulations on the developing product.[6] These peptides are often cyclic and can have highly-complex cyclic structures, although linear nonribosomal peptides are also common. Since the system is closely related to the machinery for building fatty acids and polyketides, hybrid compounds are often found. Oxazoles, thiazoles often indicate that the compound was synthesized in this fashion.[7]
Peptones
See also Tryptone
Are derived from animal milk or meat digested by proteolytic digestion. In addition to containing small peptides, the resulting spray-dried material includes fats, metals, salts, vitamins and many other biological compounds. Peptone is used in nutrient media for growing bacteria and fungi.[8]
Peptide Fragments
Refer to fragments of proteins that are used to identify or quantify the source protein.[9] Often these are the products of enzymatic degradation performed in the laboratory on a controlled sample, but can also be forensic or paleontological samples which have been degraded by natural effects.[10][11]

[edit] Peptides in molecular biology
Peptides have received prominence in molecular biology in recent times for several reasons. The first and most important is that peptides allow the creation of peptide antibodies in animals without the need to purify the protein of interest.[12] This involves synthesizing antigenic peptides of sections of the protein of interest. These will then be used to make antibodies in a rabbit or mouse against the protein.
Another reason is that peptides have become instrumental in mass spectrometry, allowing the identification of proteins of interest based on peptide masses and sequence. In this case the peptides are most often generated by in-gel digestion after electrophoretic separation of the proteins.
Peptides have recently been used in the study of protein structure and function. For example, synthetic peptides can be used as probes to see where protein-peptide interactions occur.
Inhibitory peptides are also used in clinical research to examine the effects of peptides on the inhibition of cancer proteins and other diseases.

[edit] Well-known peptide families in humans
The peptide families in this section are all ribosomal peptides, usually with hormonal activity. All of these peptides are synthesized by cells as longer "propeptides" or "proproteins" and truncated prior to exiting the cell. They are released into the bloodstream where they perform their signalling functions.

[edit] The Tachykinin peptides
Substance P
Kassinin
Neurokinin A
Eledoisin
Neurokinin B

[edit] Vasoactive intestinal peptides
VIP (Vasoactive Intestinal Peptide; PHM27)
PACAP Pituitary Adenylate Cyclase Activating Peptide
Peptide PHI 27 (Peptide Histidine Isoleucine 27)
GHRH 1-24 (Growth Hormone Releasing Hormone 1-24)
Glucagon
Secretin

[edit] Pancreatic polypeptide-related peptides
NPY
PYY (Peptide YY)
APP (Avian Pancreatic Polypeptide)
PPY Pancreatic PolYpeptide

[edit] Opioid peptides
Proopiomelanocortin (POMC) peptides
Enkephalin pentapeptides
Prodynorphin peptides

[edit] Calcitonin peptides
Calcitonin
Amylin
AGG01

[edit] Other peptides
B-type Natriuretic Peptide (BNP) - produced in myocardium & useful in medical diagnosis

[edit] Notes on terminology
A polypeptide is a single linear chain of amino acids.
A protein is one or more polypeptides more than about 50 amino acids long.
An oligopeptide or (simply) a peptide is a polypeptide less than 30-50 amino acids long.
A dipeptide has two amino acids.
A tripeptide has three amino acids.
A pentapeptide has five amino acids.
An octapeptide has eight amino acids. (e.g., angiotensin II.
A nonapeptide has nine amino acids (e.g., oxytocin).
A decapeptide has ten amino acids (e.g., gonadotropin-releasing hormone & angotensin I).
A neuropeptide is a peptide that is active in association with neural tissue.
A peptide hormone is a peptide that acts as a hormone.

[edit] See also
Peptidomimetics (such as peptoids and β-peptides) to peptides, but with different properties.
bis-peptide
Peptide synthesis
Translation
Ribosome
Argireline

[edit] References
^ Duquesne S, Destoumieux-Garzón D, Peduzzi J, Rebuffat S (2007). "Microcins, gene-encoded antibacterial peptides from enterobacteria". Natural product reports 24 (4): 708–34. doi:10.1039/b516237h. PMID 17653356.
^ Pons M, Feliz M, Antònia Molins M, Giralt E (1991). "Conformational analysis of bacitracin A, a naturally occurring lariat". Biopolymers 31 (6): 605–12. doi:10.1002/bip.360310604. PMID 1932561.
^ Torres AM, Menz I, Alewood PF, et al (2002). "D-Amino acid residue in the C-type natriuretic peptide from the venom of the mammal, Ornithorhynchus anatinus, the Australian platypus". FEBS Lett. 524 (1-3): 172–6. doi:10.1016/S0014-5793(02)03050-8. PMID 12135762.
^ Meister A, Anderson M (1983). "Glutathione". Annu Rev Biochem 52: 711 – 60. doi:10.1146/annurev.bi.52.070183.003431. PMID 6137189.
^ Hahn M, Stachelhaus T (2004). "Selective interaction between nonribosomal peptide synthetases is facilitated by short communication-mediating domains". Proc. Natl. Acad. Sci. U.S.A. 101 (44): 15585–90. doi:10.1073/pnas.0404932101. PMID 15498872.
^ Finking R, Marahiel MA (2004). "Biosynthesis of nonribosomal peptides1". Annu. Rev. Microbiol. 58: 453–88. doi:10.1146/annurev.micro.58.030603.123615. PMID 15487945.
^ Du L, Shen B (2001). "Biosynthesis of hybrid peptide-polyketide natural products". Current opinion in drug discovery & development 4 (2): 215–28. PMID 11378961.
^ Payne JW (1976). "Peptides and micro-organisms". Adv. Microb. Physiol. 13: 55–113. PMID 775944.
^ Hummel J, Niemann M, Wienkoop S, et al (2007). "ProMEX: a mass spectral reference database for proteins and protein phosphorylation sites". BMC Bioinformatics 8: 216. doi:10.1186/1471-2105-8-216. PMID 17587460.
^ Webster J, Oxley D (2005). "Peptide mass fingerprinting: protein identification using MALDI-TOF mass spectrometry". Methods Mol. Biol. 310: 227–40. PMID 16350956.
^ Marquet P, Lachâtre G (1999). "Liquid chromatography-mass spectrometry: potential in forensic and clinical toxicology". J. Chromatogr. B Biomed. Sci. Appl. 733 (1-2): 93–118. doi:10.1016/S0378-4347(99)00147-4. PMID 10572976.

VACCINE

For other uses, see Vaccine (disambiguation).
A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease.
Vaccines can be prophylactic (e.g. to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).

Name and history
The term "vaccine" derives from Edward Jenner's 1796 use of cowpox (Latin variolæ vaccinæ, adapted from the Latin vaccīn-us, from vacca cow), which, when administered to humans, provided them protection against smallpox. The earliest vaccines were based on the concept of variolation originating in China, in which a person is deliberately infected with a weak form of smallpox as a form of inoculation. Jenner realized that milkmaids who had contact with cowpox did not get smallpox. The process of distributing and administrating vaccines is thus referred to as "vaccination" .
Jenner's work was continued by Louis Pasteur and others in the 19th century. Since vaccination against smallpox was much safer than smallpox inoculation, the latter fell into disuse and was eventually banned in England in 1849.
The 19th and 20th centuries saw the introduction of several successful vaccines against a number of infectious diseases. These included bacterial and viral diseases, but not (to date) any parasitic diseases.

Types

Avian Flu vaccine development by reverse genetics techniques.
Vaccines may be dead or inactivated organisms or purified products derived from them.
There are four types of traditional vaccines:[1]
Vaccines containing killed microorganisms - these are previously virulent micro-organisms which have been killed with chemicals or heat. Examples are vaccines against flu, cholera, bubonic plague, and hepatitis A.
Vaccines containing live, attenuated virus microorganisms - these are live micro-organisms that have been cultivated under conditions that disable their virulent properties or which use closely-related but less dangerous organisms to produce a broad immune response. They typically provoke more durable immunological responses and are the preferred type for healthy adults. Examples include yellow fever, measles, rubella, and mumps. The live tuberculosis vaccine is not the contagious strain, but a related strain called "BCG"; it is used in the United States very infrequently.
Toxoids - these are inactivated toxic compounds in cases where these (rather than the micro-organism itself) cause illness. Examples of toxoid-based vaccines include tetanus and diphtheria. Not all toxoids are for micro-organisms; for example, Crotalis atrox toxoid is used to vaccinate dogs against rattlesnake bites.
Subunit - rather than introducing an inactivated or attenuated micro-organism to an immune system (which would constitute a "whole-agent" vaccine), a fragment of it can create an immune response. Characteristic examples include the subunit vaccine against HBV that is composed of only the surface proteins of the virus (produced in yeast) and the virus-like particle (VLP) vaccine against human papillomavirus (HPV) that is composed of the viral major capsid protein.
A number of innovative vaccines are also in development and in use:
Conjugate - certain bacteria have polysaccharide outer coats that are poorly immunogenic. By linking these outer coats to proteins (e.g. toxins), the immune system can be led to recognize the polysaccharide as if it were a protein antigen. This approach is used in the Haemophilus influenzae type B vaccine.
Recombinant Vector - by combining the physiology of one micro-organism and the DNA of the other, immunity can be created against diseases that have complex infection processes
DNA vaccination - in recent years a new type of vaccine, created from an infectious agent's DNA called DNA vaccination, has been developed. It works by insertion (and expression, triggering immune system recognition) into human or animal cells, of viral or bacterial DNA. Some cells of the immune system that recognize the proteins expressed will mount an attack against these proteins and cells expressing them. Because these cells live for a very long time, if the pathogen that normally expresses these proteins is encountered at a later time, they will be attacked instantly by the immune system. One advantage of DNA vaccines is that they are very easy to produce and store. As of 2006, DNA vaccination is still experimental.
While most vaccines are created using inactivated or attenuated compounds from micro-organisms, synthetic vaccines are composed mainly or wholly of synthetic peptides, carbohydrates or antigens.
Vaccines may be monovalent (also called univalent) or multivalent (also called polyvalent). A monovalent vaccine is designed to immunize against a single antigen or single microorganism.[2] A multivalent or polyvalent vaccine is designed to immunize against two or more strains of the same microorganism, or against two or more microorganisms.[3]

[edit] Developing immunity
The immune system recognizes vaccine agents as foreign, destroys them, and 'remembers' them. When the virulent version of an agent comes along the body recognises the protein coat on the virus, and thus is prepared to respond, by (1) neutralizing the target agent before it can enter cells, and (2) by recognizing and destroying infected cells before that agent can multiply to vast numbers.
Vaccines have contributed to the eradication of smallpox, one of the most contagious and deadly diseases known to man. Other diseases such as rubella, polio, measles, mumps, chickenpox, and typhoid are nowhere near as common as they were just a hundred years ago. As long as the vast majority of people are vaccinated, it is much more difficult for an outbreak of disease to occur, let alone spread. This effect is called herd immunity. Polio, which is transmitted only between humans, is targeted by an extensive eradication campaign that has seen endemic polio restricted to only parts of four countries.[2] The difficulty of reaching all children as well as cultural misunderstandings, however, have caused the eradication date to be missed several times.

[edit] Schedule
Main article: Vaccination schedule
See also: Vaccination policy
In order to provide best protection, children are recommended to receive vaccinations as soon as their immune systems are sufficiently developed to respond to particular vaccines, with additional 'booster' shots often required to achieve 'full immunity'. This has led to the development of complex vaccination schedules. In the United States, the Advisory Committee on Immunization Practices, which recommends schedule additions for the Center for Disease Control, recommends routine vaccination of children against: hepatitis A, hepatitis B, polio, mumps, measles, rubella, diphtheria, pertussis, tetanus, HiB, chicken pox, rotavirus, influenza, meningococcal disease and pneumonia. The large number of vaccines and boosters recommended (up to 24 injections by age two) has led to problems with achieving full compliance. In order to combat declining compliance rates, various notification systems have been instituted and a number of combination injections are now marketed (e.g., Prevnar and ProQuad vaccines), which provide protection against multiple diseases.
Besides recommendations for infant vaccinations and boosters, many specific vaccines are recommended at other ages or for repeated injections throughout life -- most commonly for measles, tetanus, influenza, and pneumonia. Pregnant women are often screened for continued resistance to rubella. The human papillomavirus vaccine is currently recommended in the U.S. and UK for ages 11–25. Vaccine recommendations for the elderly concentrate on pneumonia and influenza, which are more deadly to that group. In 2006, a vaccine was introduced against shingles, a disease caused by the chicken pox virus, which usually affects the elderly.
In Australia, a massive increase in vaccination rates was observed when the federal government made certain benefits (such as the universal 'Family Allowance' welfare payments for parents of children) dependent on vaccination. As well, children were not allowed into school unless they were either vaccinated or their parents completed a statutory declaration refusing to immunize them, after discussion with a doctor, and other bureaucracy. (Similar school-entry vaccination regulations have been in place in some parts of Canada for several years.) It became easier and cheaper to vaccinate one's children than not to. When faced with the annoyance, many more casual objectors simply gave in.[citation needed]

[edit] Efficacy
Vaccines do not guarantee complete protection from a disease. Sometimes this is because the host's immune system simply doesn't respond adequately or at all. This may be due to a lowered immunity in general (diabetes, steroid use, HIV infection) or because the host's immune system does not have a B-cell capable of generating antibodies to that antigen.
Even if the host develops antibodies, the human immune system is not perfect and in any case the immune system might still not be able to defeat the infection.
Adjuvants are typically used to boost immune response. Adjuvants are sometimes called the dirty little secret of vaccines [3] in the scientific community, as not much is known about how adjuvants work. Most often aluminium adjuvants are used, but adjuvants like squalene are also used in some vaccines and more vaccines with squalene and phosphate adjuvants are being tested. The efficacy or performance of the vaccine is dependent on a number of factors:
the disease itself (for some diseases vaccination performs better than for other diseases)
the strain of vaccine (some vaccinations are for different strains of the disease) [4]
whether one kept to the timetable for the vaccinations (see Vaccination schedule)
some individuals are 'non-responders' to certain vaccines, meaning that they do not generate antibodies even after being vaccinated correctly
other factors such as ethnicity or genetic predisposition
When a vaccinated individual does develop the disease vaccinated against, the disease is likely to be milder than without vaccination.
The following are important considerations in the effectiveness of a vaccination program:[citation needed]
careful modelling to anticipate the impact that an immunisation campaign will have on the epidemiology of the disease in the medium to long term
ongoing surveillance for the relevant disease following introduction of a new vaccine and
maintaining high immunisation rates, even when a disease has become rare.
In 1958 there were 763,094 cases of measles and 552 deaths in the United States.[4][5] With the help of new vaccines, the number of cases dropped to fewer than 150 per year (median of 56).[5] In early 2008, there were 64 suspected cases of measles. 54 out of 64 infections were acquired outside of the United States, and 63 of 64 either had never been vaccinated against measles, or were uncertain whether they had been vaccinated.[5]

Serum Free Media -ADVANTAGE

Serum Free Media

-In view of the disadvantages due to serum, extensive investigations have been made to develop serum-free formulations of culture media. These efforts were mainly based on the following three approaches:

(1) analytical approach based on the analysis of serum constituents,

(2) synthetic approach to supplement basal media by various combinations of growth factors, and
(3) limiting factor approach consisting of lowering the serum level in the medium till growth stops and then supplementing the medium with vitamins, amino acids, hormones, etc. till growth resumes.These approaches have resulted in several elaborate media formulations in which serum in sought to be replaced by a mixture of amino acids, vitamins, several other organic compounds, etc.; hormones, growth factors and other proteins are supplemented when required. However, addition of 5-20% of serum even in these media is essential for optimum growth.

Advantages of Serum Free Media

- 1.

Improved reproducibility of results from different laboratories and over time since variation due to batch change of serum is avoided.

2. Easier downstream processing of products from cultured cells.

3. Toxic effects of serum are avoided.

4. Biassays are free from interference due to serum proteins.

5. There is no danger of degradation of sensitive proteins by serum proteases.

6. They permit selective culture of differentiated and producing cell types from the heterogenous cultures.

FRUCTOSE

Fructose (also levulose or laevulose) is a simple reducing sugar (monosaccharide) found in many foods and is one of the three important dietary monosaccharides along with glucose and galactose. Honey, tree fruits, berries, melons, and some root vegetables, such as beets, sweet potatoes, parsnips, and onions, contain fructose, usually in combination with glucose in the form of sucrose. Fructose is also derived from the digestion of granulated table sugar (sucrose), a disaccharide consisting of glucose and fructose, and high-fructose corn syrup (HFCS).
Crystalline fructose and high-fructose corn syrup are often mistakenly confused as the same product. The former is simply pure (100%) fructose. The latter is composed of nearly equal amounts of fructose and glucose. Crystalline fructose is held to offer many unique benefits such as improved product texture, taste and stability. Specifically, when combined with other sweeteners and starches, crystalline fructose is said to boost cake height (in baked goods) and mouth-feel of foods and beverages and to produce a pleasing brown surface color and pleasant aroma when baking.[1]
Contents[hide]
1 Chemical Properties
1.1 Classification and Structure
1.2 Chemical Reactions
1.2.1 Fructose and Maillard Reaction
1.2.2 Fructose and Fermentation
2 Physical and Functional Properties
2.1 Relative Sweetness
2.2 Fructose Solubility and Crystallization
2.3 Fructose and Starch Functionality in Food Systems
3 Food Sources
3.1 Table 1 – Sugar Content of Selected Common Plant Foods (g/100g)
3.2 Commercial Sweeteners (% of Carbohydrate)
4 Digestion and Absorption
4.1 Capacity and rate of absorption
4.2 Malabsorption
5 Fructose Metabolism
5.1 Fructolysis
5.2 The Metabolism of Fructose to DHAP and Glyceraldehyde
5.3 Synthesis of glycogen from DHAP and Glyceraldehyde 3 Phosphate
5.4 Synthesis of Triglyceride from DHAP and Glyceraldehyde 3 Phosphate
6 Health effects
7 See also
8 References
9 External links
//

[edit] Chemical Properties

[edit] Classification and Structure
Fructose, also referred to as fruit sugar is a simple monosaccharide with a ketone functional group. Fructose is an isomer of glucose with the same molecular formula (C6H12O6) but with a different structure. Fructose is a 6-carbon polyhydroxyketone. Like glucose, it forms ring structures when dissolved in solution. When fructose forms a 5-member ring, the OH group on the fifth carbon atom attaches to the carbonyl group that is on the second carbon atom (D-Fructofuranose). Alternatively, the OH group on the sixth carbon may attach to the carbonyl carbon to form a 6-member ring (D-Fructopyranose). Fructose may be found at equilibrium containing a mixture of 70% fructopyranose and 30% fructofuranose [2]
Figure 1 Isomeric Forms of Fructose



[edit] Chemical Reactions

[edit] Fructose and Maillard Reaction
Fructose undergoes the Maillard reaction, non-enzymatic browning, with amino acids. Because of fructose exists to a greater extent in the open-chain form than does glucose, the initial stages of the Maillard reaction occurs more rapidly than with glucose. Therefore, fructose potentially may contribute to changes in food palatability, as well as other nutritional effects, such as excessive browning, volume and tenderness reduction during cake preparation, and formation of mutagenic compounds. [3]

[edit] Fructose and Fermentation
Fructose may be anaerobically fermented by yeast or bacteria. [4] Yeast enzymes convert sugar (glucose, or fructose) to ethanol and carbon dioxide. The carbon dioxide released during fermentation will remain dissolved in water where it will reach equilibrium with carbonic acid unless the fermentation chamber is left open to the air. The dissolved carbon dioxide and carbonic acid produce the carbonation in bottle fermented beverages. [5] Colonic bacterial fermentation of fructose and the osmotic retention of additional water in the colin may cause gas, cramps, and diarrhea in people with fructose malabsorption. [6]

[edit] Physical and Functional Properties

[edit] Relative Sweetness
The primary reason that fructose is used commercially in foods and beverages is because of its relative sweetness. It is the sweetest of all naturally occurring carbohydrates. Fructose is 1.73 times sweeter than sucrose[7][8] .
Figure 2 Relative Sweetness of Sugars and Sweeteners


The Sweetness Intensity Profile of Fructose The sweetness of fructose is perceived earlier than that of sucrose or dextrose, and the taste sensation reaches a peak (higher than sucrose) and diminishes more quickly than sucrose. Fructose can also enhance other flavors in the system[7]
Sweetness Synergy Fructose exhibits a sweetness synergy effect when used in combination with other sweeteners. The relative sweetness of fructose blended with sucrose, aspartame, or saccharin is perceived to be greater than the sweetness calculated from individual components[9].

[edit] Fructose Solubility and Crystallization
Compared to other sugars and sugar alcohols, fructose has the highest solubility. As a result, fructose is difficult to crystallize from an aqueous solution.[7] Sugar mixes containing fructose, such as candies, are softer than those containing other sugars because of the greater solubility of fructose [10].
Fructose Hygroscopicity and Humectancy Fructose is quicker to absorb moisture and slower to release it to the environment than sucrose, dextrose, or other nutritive sweeteners [9]. Fructose is an excellent humectant and retains moisture for a long period of time even at low relative humidity (RH). Therefore, fructose can contribute to improved quality, better texture, and longer shelf life to the food products in which it is used.[7]
Freezing Point Fructose has a greater effect on freezing point depression than disaccharides or oligosaccharides, which may protect the integrity of cell walls of fruit by reducing ice crystal formation. However, this characteristic may be undesirable in soft-serve or hard-frozen dairy desserts.[7]

[edit] Fructose and Starch Functionality in Food Systems
Fructose increases starch viscosity more rapidly and achieves a higher final viscosity than sucrose because fructose lowers the temperature required during gelatinizing of starch, causing a greater final viscosity [11].

[edit] Food Sources
The primary food sources of fructose are fruits, vegetables, and honey [12]. Fructose exists in foods either as a free monosaccharide or bound to glucose as the disaccharide, sucrose. Fructose, glucose, and sucrose can all be present in a food; however, different foods will have varying levels of each of these three sugars.
The sugar content of common fruits and vegetables are presented in Table 1. In general, foods that contain free fructose have equal amount of free glucose. In other words, the ratio of fructose to glucose roughly equals 1:1. A value that is above 1 indicates higher proportion of fructose to glucose and vice versa. Some of the fruits have larger proportions of fructose to glucose compared to others. For example, apples and pears contain more than twice as much free fructose as glucose, while apricots contain less than a half of fructose than glucose.
Apple and pear juices are of particular interest to pediatricians due to the juices’ high concentration of free fructose relative to glucose, which can cause diarrhea in children. The cells of the small intestine, enterocytes, have lower affinity for fructose absorption compared with that for glucose and sucrose [13]. Unabsorbed fructose creates higher osmolarity in the small intestine, which draws water into the gastrointestinal tract, resulting in osmotic diarrhea. This phenomenon is discussed in greater details in Health Effects section.
Table 1 also shows the amount of sucrose found in common fruits and vegetables. Sugar cane and sugar beet have a high concentration of sucrose, and are used for commercial preparation of pure sucrose. Extracted cane or beet juices are clarified from the impurities and concentrated by removing excess of water. The end product is 99.9% pure sucrose. Sucrose containing sugars include common white granulated sugar, powdered sugar, as well as brown sugar [14].