hormones and their act on body

DEFINITION:

Hormones are chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work.

EXPLANATION:
Hormones are secreted by specialized endocrine glands/tissues.
•    Endocrine: ductless, and secreted straight into the blood.
•    Exocrine: with ducts
It then acts on target organs to produce certain functions, and is important for the balance in the body. Many hormones are released in a pulsatile fashion (in it’s own timing, not all the time).
Here are the major endocrine glands with it’s hormones:
Hypothalamus    TRH, CRH, GHRH, GHIH, GnRH, PIF
Ant Pituitary    HH, TSH, ACTH, Prolactin, FSH, LH
Post Pituitary    Oxytocin, ADH
Thyroid    T3, T4, Calcitonin
Adrenal Cortex    Cortisol, Aldosterone
Adrenal Medulla    Epinephrine, Norepinephrine
Pancreas    Insulin, Glucagon
Parathyroid     PTH
Testes    Testosterone
Ovary    Oestrogen, Progesterone
Placenta    HCG, Human Somatomammotropin, Oestrogen, Progesterone
Kidney    Renin, Erythropoeitin, 1,25-Dihydroxycholecalciferol
Heart    ANP
Stomach    Gastrin
Small Intestine    Secretin, CCK
Adipocytes    Leptin
These hormones are produced either from Amino Acids (proteins) / Lipid Precursors (Cholesterol/Steroids)
•    Amino acid derivatives: thyroxine, serotonin
•    Peptides: Insulin, TSH, TRH, Vasopressin, Somatostatin, gonadotrophin
•    Steroids: Cortisol, sex hormones (testosterone, oestrogens, progesterone)

FUNCTIONS OF HORMONES

1.    Growth & Development
2.    Reproduction (both male & female have receptors for both male & female hormones)
3.    Production, Utilization, Energy Storage
4.    Maintain internal environment of the body
Sexual dimorphism controls the reproductive functions of the human body, this being the difference in the amount and pattern of secretions of the sexual hormones). Therefore, boys can grow into man, and girls can grow into ladies.
CHEMICAL CONSTITUTION:
One of the chemical messengers produced by endocrine glands, whose secretions are liberated directly into the bloodstream and transported to a distant part or parts of the body, where they exert a specific effect for the benefit of the body as a whole. The endocrine glands involved in the maintenance of normal body conditions are pituitary, thyroid, parathyroid, adrenal, pancreas, ovary and testis. However, these organs are not the only tissues concerned in the hormonal regulation of body processes. For example, the duodenal mucosa, which is not organized as an endocrine gland, elaborates a substance called secretin which stimulates the pancreas to produce its digestive juices. The placenta is also a very important hormone-producing tissue. See separate articles on the individual glands.The hormones obtained from extracts of the endocrine glands may be classified into four groups according to their chemical constitution:
(1) phenol derivatives, such as epinephrine, norepinephrine, thyroxine, and triiodothyronine
(2) proteins, such as the anterior pituitary hormones, with the exception of adrenocorticotropic hormone (ACTH), human chorionic gonadotropin, pregnant-mare-serum gonadotropin, and thyroglobulin
(3) peptides, such as insulin, glucagon, ACTH, vasopressin, oxytocin, and secretin
(4) steroids, such as estrogens, androgens, progesterone, and corticoids. Hormones, with a few exceptions like pituitary growth hormone and insulin, may also be classified as either tropic hormones or target-organ hormones. The former work indirectly through the organs or glands which they stimulate, whereas the latter exert a direct effect on peripheral tissues.

CHEMICAL NATURE OF HORMONE:
Chemically, most hormones belong to one of three major groups: proteins and peptides, steroids (fat-soluble molecules whose basic structure is a skeleton of four carbon rings), or derivatives of the amino acid tyrosine, characterized by a 6-carbon, or benzene, ring. There are some hormones, such as melatonin from the pineal gland and the locally acting prostaglandins, which cannot be included in any of these groups, but may share a number of their characteristics. The glands which produce protein and peptide hormones are the pituitary, certain cells of the thyroid, the parathyroids, and the pancreas. Steroids are produced by the cortex or outer layer of the adrenal gland and by the ovaries and testes. The tyrosine derivatives are the thyroid hormones, and the catecholamines (adrenaline and noradrenaline) which are produced in the medulla of the adrenal glands.

Knowledge of the chemical nature of a hormone is important as it enables one to predict how the hormone is produced, how rapidly it can be released in response to a stimulus, in what form it circulates in the blood, how it acts, the time course of its effect, and the route of administration therapeutically.

HORMONE ACTION

The chemical nature of the hormone also affects the mechanism of action. All hormones act on cells by way of their 'receptors'. Each hormone has its own receptor to which it binds, matching rather like a lock and key. This is why hormones circulating throughout the body in the blood may leave capillaries to enter the extracellular fluid of many tissues, but act only on those cells which possess the appropriate receptor. Proteins and peptides cannot enter the cell and so act via cell membrane receptors, producing their effects by 'second messengers', which are activated in the cell as soon as the hormone binds to the receptor. Thus peptide hormones can produce quite rapid responses. Steroid and thyroid hormones, by contrast, can enter the cell and bind to intracellular receptors, producing their effects by stimulating the production of new proteins. There is therefore a relatively long lag period before the response to these hormones is seen.

Hormones produce a variety of responses throughout the body and may be grouped according to their actions, although there is overlap between the groups.

First there are the metabolic hormones which control the digestion of food, its storage and use. Such hormones include those produced by the digestive tract, which control secretion of digestive juices and activity of the muscle in the wall of the tract; also the hormones which regulate blood glucose, namely insulin, (which lowers it), and glucagon, growth hormone, the thyroid hormones, and cortisol, which all raise it.

Second are the hormones which regulate the composition of the blood, and hence of all the body fluids. Excluding those that regulate the glucose content, these are: aldosterone and atrial natriuretic hormone (produced in the heart), which control the amount of sodium in the blood; vasopressin or antidiuretic hormone, which controls the amount of water; parathyroid hormone and vitamin D, which raise blood calcium; and calcitonin, which lowers blood calcium. It is perhaps surprising to learn that a vitamin can also be a hormone, but it is similar in many ways to the steroid hormones, and the active form is produced in one part of the body for action an another. The vitamin D taken in the diet or formed in the skin under the action of UV light is not the active form: this is produced after modification takes place first in the liver and then the kidney.

Next are the stress hormones, primarily adrenaline and noradrenaline, which are under the control of the autonomic nervous system: cortisol and a number of the pituitary hormones are also involved in the response to stress.

A further group are those responsible for growth, development, and reproduction. These include growth hormone itself, and the hormones controlling ovarian and testicular function (luteinizing hormone, LH, and follicular stimulating hormone, FSH) - all of which come from the pituitary - and the hypothalamic hormones, which in turn control these pituitary secretions. Included also are the steroid hormones, produced by the ovaries (oestrogens and progesterone) and testes (testosterone), and those hormones involved in birth and lactation, chiefly oxytocin and prolactin.

The final major group includes those hormones that control other endocrine systems, and therefore interact with the other groups. The pituitary hormones adrenocorticotrophic hormone (ACTH), thyroid stimulating hormone (TSH), and the gonadotrophic hormones LH and FSH control the release of some of the metabolic and stress hormones and of the reproductive hormones, whilst hypothalamic hormones in turn control pituitary function.

HOW THEY ACT ON OUR BODY

A hormone will act on target tissues. Imagine it as a homing missile. When the hormone reaches the target tissues, it either acts on the plasma membrane of the cells (peptide hormones and epinephrine) or in the cytosol/nucles (steroid, thryroid hormones, active vit D3, retinoic acid). It is very specific in that sense.
The component that receives the hormone is called a receptor, a protein. When the hormone binds into the receptor’s active site, a series of mechanism takes place which at last produces the intended action. However, the interaction is swift and reversible, so there will be a rapid onset (quick action) and then the action will be terminated (not permanent). The hormones secreted is very very little (in pico/nanomole concentrations) therefore, the receptor affinity must be high, meaning the receptor must be willing to accept the hormone. When the hormone is needed badly, the receptor is up-regulated (increase) or vice versa – down-regulated.
When the hormone binds to the receptor (ligand interaction), the receptor will undergo conformational changes (change shape), which activates G-protein in the cell (which can be stimulatory, Gs, or inhibitory, Gi). Assuming that it is stimulatory, it will cause phosphorylation of GDP to convert to GTP which will bind to the effector (enzyme adenylyl cyclase) coverting ATP to cAMP. cAMP will activate Protein Kinase A which inturn will lead to phosphorylation of intracellular mediators called second messengers (relay message from the hormone) producing intracellular effects.

Since intracellular receptors are in the cell which is bounded by the phospholipid bilayer, hormones have different mechanisms to enter the cell. Steroids are cholesterol derivatives, therefore it is a lipid and will be able enter thru the cell membrane by simple diffusion. Thyroid hormones however enter the cell thru facilitated diffusion.
As usual, when a hormone binds to the receptor, the receptor undergo conformational changes when activated, therefore it becomes competent to bind to DNA stimulating transcription. Small amounts of hormone will bring about major physiologic effect.
Therefore, it is important to have a control/ feedback mechanism to control these actions. Most hormones when in high amounts will bring about a negative feedback, only certain hormones like LH and Oxytocin encourages positive feedback.
Besides the amount of hormone, hormones are also controlled and secreted in bursts, such as during sleep,following a diurnal cycle, aging and stages of development.
Growth hormone: High during strenuous exercise and 1st few hours of deep sleep.
ACTH & Cortisol: High during last few hours before waking up, uptil several hours after waking up.
FSH & LH: Following the normal menstrual cycle.
Hormones can be measured using immunoassay (usually double sandwich ELISA), where monoclonal antibodies will bind to specific epitopes on the hormone, producing a formation of a colored fluorescent product. The amount of these fluorescent products will then be measured using optical methods such as: spectrophotometer, fluro meter, lumino meter, or radio chemical assays.
As we know different hormones are released in different timings, therefore it is best to determine the optimum time to get a blood sample, or by serial measurements.

viruses and their reproduction

Introduction of viruses.

Viruses are infectious pathogens that are too small to be seen with a light microscope, but despite their small size they can cause chaos. The simplest viruses are composed of a small piece of nucleic acid surrounded by a protein coat. As is the case with other organisms, viruses carry genetic information in their nucleic acid which typically specifies three or more proteins. All viruses are obligate parasites that depend on the cellular machinery of their hosts to reproduce. Viruses are not active outside of their hosts, and this has led some people to suggest that they are not alive. All types of living organisms including animals, plants, fungi, and bacteria are hosts for viruses, but most viruses infect only one type of host. Viruses cause many important plant diseases and are responsible for losses in crop yield and quality in all parts of the world.
The purpose of this chapter is to provide an overview of the fascinating microscopic world of plant viruses and to describe the basic concept of a virus, the structure of virus particles and genomes, virus life cycles, the evolution and diversity of plant viruses, as well as the common manifestations of plant virus diseases and major approaches to managing these diseases. We hope to convey to the reader our grudging admiration for these small pathogens and for their success in manipulating their plant hosts so successfully.

Basic Biology.

Viruses represent not just another group of pathogens, but rather a fundamentally different form of life. Unlike all other living organisms, viruses are non-cellular. In contrast to cells, which multiply by dividing into daughter cells, viruses assemble from pools of their structural components. Mature virus particles are dormant; they come alive and reproduce only inside infected cells. In other words, viruses are obligate parasites that cannot be cultivated using any growth media suitable for bacterial, fungal, plant or animal cell types. All viruses lack protein-synthesizing and energy-producing apparatuses. As a rule, virus particles are immobile outside the infected host; they rely on the aid of other organisms or the environment for their dissemination.

Morphology.

There is a simple structural principle that applies to virtually all viruses in their mature form. Virus particles (virions) are composed of two principal parts, the genome that is made of nucleic acid, and a protective shell that is made of protein. In addition, some virus particles are enveloped by an outer membrane containing lipids and proteins (lipoprotein membrane). The protein shells of plant viruses (capsids) are assembled in accord with one of the two fundamental types of symmetry. The first type of virion is helical (roughly elongated). The elongated viruses come in two major variants, rigid rods and flexuous filaments. In both of these variants, the nucleic acid is highly ordered: it assumes the same helical conformation as the proteinaceous capsid. The second type of virus particle is icosahedral (roughly spherical; the variations of this basic shape include bacilliform virions and twin virions composed of two joined incomplete icosahedra . In the icosahedral virions, the genomic nucleic acid forms a partially ordered ball inside the proteinaceous capsid. The icosahedral and elongated virions alike can self-assemble in a test tube if the nucleic acid and protein subunits are incubated under proper conditions.
Viruses are the smallest among all known organisms. The typical diameter of a spherical plant virus is ~30 nm. The rigid, rod-shaped TMV particle is 300 x 18 nm and consists of an RNA genome of about 6,400 nucleotides encapsidated by 2,130 copies of the TMV coat protein. Some of the filamentous viruses reach the length of ~2000 nm or 2 µm. For comparison, the typical size of a leaf mesophyll cell is ~50 µm.
Reproduction
As in other organisms, the information for virus reproduction is contained within its genome.
Althouh the genetic material for most organisms is double-stranded (ds) DNA, only a minority of plant viruses possess ds DNA genomes. Some of the plant viruses have genomes that are composed of single-stranded (ss) DNA. However, the majority of plant viruses do not use DNA at all. Instead, the genomes of nearly all plant viruses are made of RNA. Most of these genomes are composed of ssRNA that is the same (positive-sense) polarity as the messenger RNAs of the cell. Some of the RNA viruses use ssRNAs of negative polarity, and yet others have genomes made of dsRNA. Due to this enormous variation in the very nature of the genetic material of viruses, the reproductive cycles and life styles of different viruses are often very distinct from each other.
Since plant viruses are obligate, biographic parasites, their life cycles start by penetration of the virion into the cell. Plant viruses are unable to penetrate the plant cuticle and cell wall. It is believed that the virion enters the cytoplasm of the cell passively through wounds caused by mechanical damage to the cuticle and cell wall. The next phase of virus infection is the partial or complete removal of the coat protein shell of the virion in the cytoplasm. Next the cell mediates expression of the viral genome by providing a transcription apparatus (for DNA viruses) and a translation apparatus (for all viruses). The DNA viruses must be transported to the nucleus for transcription in order to gain access to the cell proteins required for the production of messenger RNA from viral DNA. Translation of viral RNA in the cytoplasm produces viral proteins that are required for completion of the virus life cycle.
All viruses must direct the formation of at least three types of proteins: replication proteins that are essential for nucleic acid production, structural proteins that form the protein shell and other components contained in the virions, and movement proteins that mediate virus transport between plant cells .The viral replication proteins combine with cellular proteins to produce a complex of proteins that manufactures multiple copies of the virus genome. These newly made genomes interact with the structural proteins to form new virions.

gymnosperms importance

Gymnosperms Importance:

Here is the impotance of  Gymnosperms
Gymnosperm consists of about 700 species of woody plants with seeds which are not enclosed by fruits. It is a group of seed-producing plants that includes Ginkgo, conifers, and cycads, which is an opposed to an angiosperm whose seeds are enclosed fruits or by mature ovaries.

Generations in Gymnospermic plants.

Gymnosperms, like all vascular plants have a sporophyte-dominant life-cycle like the Conifers which are far the most abundant extant group of gymnosperms with six to eight families. It’s a woody plant and most are evergreen, there leaves are long, thin and needle-like not like an ordinary plant leaves. Seeds which are not borne inside a fruit are said to be “naked”. The name of the class comes from the Greek words gymnos which means naked and sperma which means seed. Gymnosperm includes two phyla plants which are the Phylum Cycadophyta and Phylum Coniferophyta   

 Gymnosperms As Ornamentals.

Gymnosperms plants are widely used as ornamentals. Conifers are often featured in formal gardens and are used for bonsai. Yews and junipers are often low-growing shrubs cultivated for ground cover and hedges. Conifers are effective windbreaks, especially those that are evergreen. Cycads are used as garden plants in warmer latitudes, and some may even thrive indoors. Their leathery green foliage and sometimes colourful cones are striking. Ginkgo is a hardy tree, and although it once approached extinction, it is now cultivated extensively and survives such challenging habitats as the streets of New York City. 
Some gymnosperms are weedy in that they invade disturbed areas or abandoned agricultural land. Pines and junipers are notorious invaders, making the land unusable for growing crops    source of Lumber
Most of the commercial lumber in the Northern Hemisphere is derived from the trunks of conifers such as pine, Douglas fir, spruce, fir, and hemlock. Araucaria, kauri, and Podocarpus are important conifers of the Southern Hemisphere used for lumber. The wood is straight-grained, light for its strength, and easily worked. Wood of gymnosperms is often called softwood to differentiate it from the hardwood angiosperms. Wood of angiosperms typically has more kinds of elements than does softwood of gymnosperms. In addition to its use in building construction, gymnosperms wood is used for utility poles and railroad ties. Aromatic wood of cedar is frequently used in the construction of closets or clothes chests and apparently repels cloth-eating moths. Most plywood is gymnosperms. Fibres of conifers make up paper pulp and may occasionally be used for creating artificial silk or other textiles. Conifers are frequently planted in reforestation projects. Conifer bark is often the source of compounds involved in the leather tanning industry. Bark is also used extensively as garden mulch.

Manufacture of paints and varnish.

From conifer resins are derived turpentine, rosin, and wood alcohol (methanol). A hardened form of resin from a kauri (Agathis australis), called copal, is used in the manufacture of paints and varnishes. Some resins, such as balsam (from hemlock) and dammar (from Agathis) are used in the preparation of mounting media for microscope slides. Many types of amber are derived from fossilized resin of conifers.

Source of Oil use in Scents.

 Commercially useful oils are derived from such conifers as junipers, pines, hemlock, fir, spruces, and arborvitae. These oils serve as air fresheners, disinfectants, and scents in soaps and cosmetics.
•    Source of Food
Seeds are often food sources. Roasted pine seeds are a delicacy eaten plain or used as a garnish on bakery products. Seeds of Ginkgo and cycads may be poisonous unless detoxified. “Berries” (in reality the fleshy cones) of juniper are used to flavour gin.
Although gymnosperm consist of about 500 species only, the rank among most economically important plant; many species of the group are significant as timber trees, food and medicinal plants. In forest, gymnosperms are important in erosion control, protection of water sheds and enhancement of aesthetic value of natural communities.

Biological Importance.

Gymnosperms are of great biological importance because of their diversity of form and structure, and of their well documented fossil record. Of interest, too, to naturalist is the tallest tree representative of the gymnosperm, the Giant redwood ( Sequoia-dendron giganteum )which rise to more than 100 meters above the ground. Gymnosperms have major economic uses like the fir; spruce, Pine, and cedar which are all examples of conifers that are used for lumber. Some other common uses for gymnosperms are soap, varnish, nail polish, food, gum, and perfumes.

The tallest flora in the world

The giant redwood (Sequoiadendron giganteum) a coniferous plant is the reigning tallest living organism in the world. The tallest redwood tree is more than 112 meters in height. It can be found in the Redwood National park in California. Coast redwood is one of the most valuable timber species in the lumbering industry which is the sole living species of the genus Sequoia in the cypress family Cupressaceae. Which is the tallest tree living now on Earth.
Gymnosperms account for approximately 75 percent of the world's timber and a large amount of the wood pulp used to make paper. In North America the white spruce, Picea glauca, is the main source of pulpwood used for newsprint and other paper. Other spruce wood is used by to manufacture violins and similar string instruments because the wood produces a desired resonance. The Douglas fir, Pseudotsuga menziesii, provides more timber than any other North American tree species and produces some of the most-desirable lumber in the world. The wood is strong and relatively free of knots. Uses for the wood include house framing, plywood production, structural beams, pulpwood, railroad ties, boxes, and crates. Since most naturally occurring areas of growth have been harvested, the Douglas fir is being grown in managed forests. The wood from the redwood Sequoia sempiternal is used for furniture, fences, posts, some construction, and has various garden uses.

Importance in paper industry.

In addition to the wood and paper industry, gymnosperms are important in making resin and turpentine. Resin, the sticky substance in the resin canals of conifers, is a combination of turpentine, a solvent, and a waxy substance called rosin. Turpentine is an excellent paint and varnish solvent but is also used to make deodorants, shaving lotions, medications, and limonene-a lemon flavoring used in the food industry. Resin has many uses; it is used by baseball pitchers to improve their grip on the ball and by batters to improve their grip on the bat; violinists apply resin to their bows to increase friction with the strings; dancers apply resin to their shoes to improve their grip on the stage.

tips to help prevent medical errors

Tips To Help Prevent Medical Errors:

According to patient fact sheet here are some steps to understands medical errors.
Medical errors can occur anywhere in the health care system: In hospitals, clinics, surgery centers, doctors' offices, nursing homes, pharmacies, and patients' homes. Errors can involve medicines, surgery, diagnosis, equipment, or lab reports. These tips tell what you can do to get safer care.
Most errors result from problems created by today's complex health care system. But errors also happen when doctors* and patients have problems communicating. These tips tell what you can do to get safer care.
What You Can Do to Stay Safe
The best way you can help to prevent errors is to be an active member of your health care team. That means taking part in every decision about your health care. Research shows that patients who are more involved with their care tend to get better results.

Medicines:

Make sure that all of your doctors know about every medicine you are taking.
This includes prescription and over-the-counter medicines and dietary supplements, such as vitamins and herbs.
 Bring all of your medicines and supplements to your doctor visits.
Your medicines can help you and your doctor talk about them and find out if there are any problems. It can also help your doctor keep your records up to date and help you get better quality care.
 Make sure your doctor knows about any allergies and adverse reactions you have had to medicines.
This can help you to avoid getting a medicine that could harm you.
When your doctor writes a prescription for you, make sure you can read it.
If you cannot read your doctor's handwriting, your pharmacist might not be able to either.
Ask for information about your medicines in terms you can understand both when your medicines are prescribed and when you get them:
Is this medicine safe to take with other medicines or dietary supplements I am taking?
What food, drink, or activities should I avoid while taking this medicine?
When you pick up your medicine from the pharmacy, ask: Is this the medicine that my doctor prescribed
Ask your pharmacist for the best device to measure your liquid medicine.
For example, many people use household teaspoons, which often do not hold a true teaspoon of liquid. Special devices, like marked syringes, help people measure the right dose.
Ask for written information about the side effects your medicine could cause.
If you know what might happen, you will be better prepared if it does or if something unexpected happens.
Hospital Stays
If you are in a hospital, consider asking all health care workers who will touch you whether they have washed their hands.
Hand washing can prevent the spread of infections in hospitals.
When you are being discharged from the hospital, ask your doctor to explain the treatment plan you will follow at home.
This includes learning about your new medicines, making sure you know when to schedule follow-up appointments, and finding out when you can get back to your regular activities.
It is important to know whether or not you should keep taking the medicines you were taking before your hospital stay. Getting clear instructions may help prevent an unexpected return trip to the hospital.

Surgery:

If you are having surgery, make sure that you, your doctor, and your surgeon all agree on exactly what will be done.
Having surgery at the wrong site (for example, operating on the left knee instead of the right) is rare. But even once is too often. The good news is that wrong-site surgery is 100 percent preventable. Surgeons are expected to sign their initials directly on the site to be operated on before the surgery.
If you have a choice, choose a hospital where many patients have had the procedure or surgery you need.
Research shows that patients tend to have better results when they are treated in hospitals that have a great deal of experience with their condition.
Speak up if you have questions or concerns.
You have a right to question anyone who is involved with your care.
Make sure that someone, such as your primary care doctor, coordinates your care.
This is especially important if you have many health problems or are in the hospital.
Make sure that all your doctors have your important health information.
Do not assume that everyone has all the information they need.
Ask a family member or friend to go to appointments with you.
Even if you do not need help now, you might need it later.
Know that "more" is not always better.
It is a good idea to find out why a test or treatment is needed and how it can help you. You could be better off without it.
If you have a test, do not assume that no news is good news.
Ask how and when you will get the results.
Learn about your condition and treatments by asking your doctor and nurse and by using other reliable

cancer causing viruses and its vaccine

Cancer causing viruses and its vaccine

 Today we discussing about cancer and its vaccination

Cancer:

Cancer , known medically as a malignant neoplasm, is a broad group of diseases involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invading nearby parts of the body. The cancer may also spread to more distant parts of the body through the lymphatic system or bloodstream. Not all tumors are cancerous; benign tumors do not invade neighboring tissues and do not spread throughout the body. There are over 200 different known cancers that affect humans.

Viruses:

Viruses also have the ability to cause cancer by altering cell genes. Cancer viruses change cells by integrating their genetic material with the host cell's DNA. The infected cell is regulated by the viral genes and gains the ability to undergo abnormal new growth. Several viruses have been linked to certain types of cancer in humans. The Epstein-Barr virus has been linked to Burkitt's lymphoma, the hepatitis B virus has been linked to liver cancer, and the human papilloma viruses have been linked to cervical cancer.

Viruses and Cancer:

Cancer (Latin cancer, crab) is one of our most serious medical problems and the focus of an immense amount of interest and research.A tumor (Latin tumere, to swell) is a growth or lump of tissue resulting from neoplasia or abnormal new cell growth and reproduction due to a loss of regulation. Tumor cells have aberrant shapes and altered plasma membranes that contain distinctive tumor antigens. They may invade surrounding tissues to form unorganized cell masses. They often lose the specialized metabolic activities characteristic of differentiated tissue cells and rely greatly upon anaerobic metabolism. This reversion to a more primitive or less differentiated state is called anaplasia. There are two major types of tumors with respect to overall form or growth pattern. If the tumor cells remain in place to form a compact mass, the tumor is benign. In contrast, malignant or cancerous tumor cells can actively spread throughout the body in a process known as metastasis, often by floating in the blood and establishing secondary tumors. Some cancers are not solid, but cell suspensions. For example, leukemias are composed of malignant white blood cells that circulate throughout the body. Indeed, dozens of kinds of cancers arise from a variety of cell types and afflict all kinds of organisms.
At present, viruses have been implicated in the genesis of atleast eight human cancers:
1 ) The Epstein-Barr virus (EBV) is one of the best-studied human cancer viruses. EBV is a herpes virus and the cause of two cancers. Burkitt’s lymphoma is a malignant tumor of
the jaw and abdomen found in children of central and western Africa. EBV also causes nasopharyngeal carcinoma. Both the virus particles and the EBV genome have been found within tumor cells; Burkitt’s lymphoma patients also have high blood levels of antibodies to EBV.Interestingly there is some reason to believe that a person also must have had malaria to develop Burkitt’s lymphoma. Environmental factors must play a role, because EBV does
not cause much cancer in the United States despite its prevalence. Possibly this is due to a low incidence of malaria in the United States.
2) Hepatitis B virus appears to be associated with one form of liver cancer (hepatocellular carcinoma) and can be integrated into the human genome.
3) Hepatitis C virus causes cirrhosis of the liver, which can lead to liver cancer.
4) Human herpes virus 8 is associated with the development of Kaposi’s sarcoma.
5) Some strains of human papilloma viruses have been linked to cervical cancer.
6) At least two retroviruses, the human T-cell lymphotropic virus I (HTLV-1) and HTLV-2, seem able to cause cancer, adult T-cell leukemia, and hairy-cell leukemia, respectively  Other retrovirus-associated cancers may well be discovered in the future.It appears that viruses can cause cancer in several ways. They may bring oncogenes into a cell and insert them into its
genome. Rous sarcoma virus (a retrovirus) carries an src gene that codes for tyrosine kinase. This enzyme is located mainly in the plasma membrane and phosphorylates the amino acid tyrosine in several cellular proteins. It is thought that this alters cell growth and behavior. Since the activity of many proteins is regulated by phosphorylation and several other oncogenes also code for protein kinases, many cancers may result at least partly from altered cell regulation due to changes in kinase activity. The human T-cell lymphotropic viruses, HTLV-1 and HTLV-2, seem to transform T cells by producing a regulatory protein that sometimes activates genes involved in cell division as well as stimulating virus reproduction. Some oncogenic viruses carry one or more very effective promoters oenhancers. If these viruses integrate themselves next to a cellular oncogene, the promoter or enhancer will stimulate its transcription,leading to cancer.
Causes of Cancer:
Cancer results from the development of abnormal properties in normal cells that enable them to grow excessively and spread to other locations. This abnormal development can be caused by mutations that occur from factors such as chemicals, radiation, ultraviolet light, and chromosome replication errors. These mutagens alter DNA by changing nucleotide bases and can even change the shape of DNA. The altered DNA produces errors in DNA replication, as well as errors in protein synthesis. These changes influence cell growth, cell division, and cell aging.
Cancer Cell Properties:
Cancer cells have characteristics that differ from normal cells.

•    Cell Reproduction

Cancer cells acquire the ability to reproduce uncontrollably. These cells may have gene mutations or chromosome mutations that affect the reproductive properties of the cells. Cancer cells gain control of their own growth signals and continue to multiply unchecked. They don't experience biological aging and maintain their ability to replicate and grow.
•    Cell Communication
Cancer cells lose the ability to communicate with other cells through chemical signals. They also lose sensitivity to anti-growth signals from surrounding cells. These signals normally restrict cellular growth.

•    Cell Adhesion

 Cancer cells lose the adhesion molecules that keep them bonded to neighboring cells. Some cells have the ability to metastasize or spread to other areas of the body through the blood or lymph fluid. Once in the bloodstream, cancer cells release chemical messengers called chemokines that enable them to pass through blood vesselsinto the surrounding tissues.
•    Cell Specialization
Cancer cells are unspecialized and do not develop into cells of a specific type. Similar to stem cells, cancer cells proliferate or replicate many times, for long periods of time. Cancer cell proliferation is rapid and excessive as these cells spread through out the body.

•    Cell Death

 When the genes in a normal cell are damaged beyond repair, certain DNA checking mechanisms signal for cell destruction. Mutations that occur in gene checking mechanisms allow for the damages to go undetected. This results in the loss of the cell's ability to undergo programmed cell death.
Retroviruses:
Retroviruses are viruses with an RNA genome (RNA viruses), that replicate by way of reversetranscription of their RNA into DNA. These viruses penetrate their cell host intact. Once inside, their capsid protein coat is removed, releasing a single stranded RNA genome. An RNA-dependent DNA polymerase, encoded by the virus, generates a complementary DNA strand which becomes integrated into the host cell genome and serves as the template for the synthesis of new viral RNA genomes. Protein synthesis from these genomes results in development of new viral progeny which are released slowly from the host cell by budding, thereby not causing lysis and death of the infected cell, but allowing ongoing replication of new viruses.
Retroviruses are responsible for causing some forms of leukemia (a type of cancer) in humans, and the virus that causes AIDs (HIV) is a retrovirus. Despite this, retroviruses are also useful tools for protein engineering, used for introducing new genes into a host cell. These types of virus integrate into host DNA at random sites, however, therefore the locations for gene insertions cannot (as yet) be controlled.
Discovering the First Cancer-Causing Virus: A farmer had brought him a hen with a large lump in her breast. Rous, a pathologist, diagnosed the lump as a sarcoma a tumor of cells in the connective tissue. He first tested whether the tumor could be transplanted into chickens closely related to the original one. It could, and with each passing, the tumor became more aggressive. To find out whether an infectious agent caused the cancer, Rous prepared an extract he minced a sample of the tumor tissue in saline solution and passed this through a filter to eliminate bacteria and tumor cells. Then he injected the extract into healthy chickens. Contrary to his expectations, it produced new tumors.
Describing these experiments, Rous suggested that the tumor-inducing agent was "a minute parasitic organism"a virus. There are two types of cancers caused by viruses: acutely transforming or slowly transforming cancers. In acutely transforming viruses, the virus carries an overactive oncogene, and the infected cell becomes cancerous as soon as the overactive viral gene is expressed. In contrast, in slowly transforming viruses, the virus genome is inserted near a previously existing proto-oncogene in the genome of the infected cell. The virus causes overexpression of that proto-oncogene, which typically induces uncontrolled cell division. Because the virus' genes might not insert near enough to a proto-oncogene to trigger the cancerous changes, and, even if optimally located, it might take some time to become activated, slowly transforming viruses usually cause tumors much longer after infection than the acutely transforming viruses.
Infection by some hepatitis viruses, especially hepatitis B and hepatitis C, can induce a chronic viral infection that leads to liver cancer in about 1 in 200 of people infected with hepatitis B each year (more in Asia, fewer in North America), and in about 1 in 45 of people infected with hepatitis C each year. People with chronic hepatitis B infection are more than 200 times more likely to develop liver cancer than uninfected people. Liver cirrhosis, whether from chronic viral hepatitis infection or alcohol abuse or some other cause, is independently associated with the development of liver cancer, and the combination of cirrhosis and viral hepatitis presents the highest risk of liver cancer development. Because chronic viral hepatitis is so common, and liver cancer so deadly, liver cancer is one of the most common causes of cancer-related deaths in the world, and is especially common in East Asia and parts of sub-Sarahan Africa.
Human papillomaviruses (HPV) are another particularly common cancer-causing virus. HPV is well known for causing genital warts and essentially all cases of cervical cancer, but it can also infect and cause cancer in several other parts of the body, including the larynx, lining of the mouth, nose, and throat, anus, and esophagus. The Papanicolaou smear ("Pap" smear) is a widely used cancer screening test for cervical cancer. DNA-based tests to identify the virus are also available.
Herpesviruses are a third group of common cancer-causing viruses. Two types of herpesviruses have been associated with cancer: the Epstein-Barr virus (EBV) and human herpesvirus 8 (HHV-8). EBV appears to cause all nonkeratinizing nasopharyngeal carcinomas and some cases of lymphoma, including Burkitt’s lymphoma the association is especially strong in Africa—and Hodgkin’s disease. EBV has also been found in a variety of other types of cancer cells, although its role in causing these other cancers is not well established. HHV-8 causes all cases of Kaposi’s sarcoma, and has been found in some cases of a cancer-related condition called Castleman's disease. Studies involving other kinds of cancer, particularly prostate cancer, have been inconsistent. Both of these herpesviruses are commonly found in cancerous cells of primary effusion lymphoma. Herpesviruses also cause cancer in animals, especially leukemias and lymphomas.
HIV does not directly cause cancer, but it is associated with a number of malignancies, especially Kaposi's sarcoma, non-Hodgkin's lymphoma, anal cancer and cervical cancer. Kaposi's sarcoma is caused by human herpesvirus 8. AIDS-related cases of anal cancer and cervical cancer are commonly caused by human papillomavirus. After HIV destroys the immune system, the body is no longer able to control these viruses, and the infections manifest as cancer. Certain other immune deficiency states (e.g. common variable immunodeficiency and IgA deficiency) are also associated with increased risk of malignancy.
Cancer vaccines:
Preventative vaccines, like those that protect against viruses or the flu, are given before a person becomes sick.  In recent years, scientists have been attempting to develop therapeutic vaccines, with the first successful prostate cancer vaccine called Provenge approved in 2010 by the US FDA.  In contrast to preventive vaccines the therapeutic cancer vaccines are given to a person who already has the disease. Therapeutic cancer vaccines are designed to treat cancer by boosting the immune system to fight against the cancer.
Cancer vaccines are active immunotherapies because they are meant to trigger the patient's immune system to respond. Cancer vaccines are targeted because they do not just boost the immune system in general, but because they cause the immune system to attack the cancer cells, honing in on one or more specific tumor antigens.

Examples of Cancer vaccines

         The examples of Cancer vaccines include: Tumor cell vaccines, Antigen Vaccines, Dendritic cell vaccines (Provenge), Anti-idiotype vaccines, DNA vaccines, Vector-based vaccines.   
A cancer vaccine may contain cancer cells, parts of cells, or purified tumor-specific antigens and is designed to increase the targeted immune response against cancer cells already present in the patient. A cancer vaccine may be combined with other substances or cells called adjuvants that help boost the immune response even further.
Cancer vaccines generally fall into two categories: a) cell-based cancer vaccines, which are created using cells from the patient's own cancer that have been presented to and cultured with the patient's own immune system cells.  These activated immune cells from the patient are delivered back to the same patient with other proteins (e.g., IL-2) to further facilitate immune activation of these tumor antigen primed immune cells; and b) vector-based cancer vaccines in which an engineered virus, or other vector, is used to introduce cancer specific proteins and other molecules to the patient in order to stimulate the patient's immune system to recognize the tumor cells and fight the cancer.
Both approaches are designed to stimulate the patient's own immune system to attack tumor cells.

what is protein and its features

      Protein and its features :  

A representation of the 3D structure of the protein myoglobin showing turquoise alpha helices. This protein was the first to have its structure solved by X-ray crystallography. Towards the right-center among the coils, a prosthetic group called a heme group (shown in gray) with a bound oxygen molecule (red).
Proteins : Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, replicating DNA, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in folding of the protein into a specific three-dimensional structure that determines its activity.
A polypeptide is a single linear polymer chain derived from the condensation of amino acids. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids; however, in certain organisms the genetic code can include selenocysteine and in certain archaea pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by posttranslational modification, which alters the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors. Proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes.
Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells. Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. Proteins are also necessary in animals' diets, since animals cannot synthesize all the amino acids they need and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.
Proteins may be purified from other cellular components using a variety of techniques such as ultracentrifugation, precipitation, electrophoresis, and chromatography; the advent of genetic engineering has made possible a number of methods to facilitate purification. Methods commonly used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, nuclear magnetic resonance and mass spectrometry.

Biochemistry

Main articles: Biochemistry, Amino acid, and peptide bond
Chemical structure of the peptide bond (bottom) and the three-dimensional structure of a peptide bond between an alanine and an adjacent amino acid (top/inset)
Resonance structures of the peptide bond that links individual amino acids to form a protein polymer
Most proteins consist of linear polymers built from series of up to 20 different L-a-amino acids. All proteinogenic amino acids possess common structural features, including an a-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this basic structure as it contains an unusual ring to the N-end amine group, which forces the CO–NH amide moiety into a fixed conformation.[1] The side chains of the standard amino acids, detailed in the list of standard amino acids, have a great variety of chemical structures and properties; it is the combined effect of all of the amino acid side chains in a protein that ultimately determines its three-dimensional structure and its chemical reactivity.[2] The amino acids in a polypeptide chain are linked by peptide bonds. Once linked in the protein chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen, and oxygen atoms are known as the main chain or protein backbone.[3]
The peptide bond has two resonance forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar. The other two dihedral angles in the peptide bond determine the local shape assumed by the protein backbone.[4] The end of the protein with a free carboxyl group is known as the C-terminus or carboxy terminus, whereas the end with a free amino group is known as the N-terminus or amino terminus. The words protein, polypeptide, and peptide are a little ambiguous and can overlap in meaning. Protein is generally used to refer to the complete biological molecule in a stable conformation, whereas peptide is generally reserved for a short amino acid oligomers often lacking a stable three-dimensional structure. However, the boundary between the two is not well defined and usually lies near 20–30 residues.[5] Polypeptide can refer to any single linear chain of amino acids, usually regardless of length, but often implies an absence of a defined conformation.
Synthesis

Biosynthesis

Main article: Protein biosynthesis
A ribosome produces a protein using mRNA as template.
The DNA sequence of a gene encodes the amino acid sequence of a protein.
Proteins are assembled from amino acids using information encoded in genes. Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene encoding this protein. The genetic code is a set of three-nucleotide sets called codons and each three-nucleotide combination designates an amino acid, for example AUG (adenine-uracil-guanine) is the code for methionine. Because DNA contains four nucleotides, the total number of possible codons is 64; hence, there is some redundancy in the genetic code, with some amino acids specified by more than one codon.[6] Genes encoded in DNA are first transcribed into pre-messenger RNA (mRNA) by proteins such as RNA polymerase. Most organisms then process the pre-mRNA (also known as a primary transcript) using various forms of Post-transcriptional modification to form the mature mRNA, which is then used as a template for protein synthesis by the ribosome. In prokaryotes the mRNA may either be used as soon as it is produced, or be bound by a ribosome after having moved away from the nucleoid. In contrast, eukaryotes make mRNA in the cell nucleus and then translocate it across the nuclear membrane into the cytoplasm, where protein synthesis then takes place. The rate of protein synthesis is higher in prokaryotes than eukaryotes and can reach up to 20 amino acids per second.[7]
The process of synthesizing a protein from an mRNA template is known as translation. The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodon located on a transfer RNA molecule, which carries the amino acid corresponding to the codon it recognizes. The enzyme aminoacyl tRNA synthetase "charges" the tRNA molecules with the correct amino acids. The growing polypeptide is often termed the nascent chain. Proteins are always biosynthesized from N-terminus to C-terminus.[6]
The size of a synthesized protein can be measured by the number of amino acids it contains and by its total molecular mass, which is normally reported in units of daltons (synonymous with atomic mass units), or the derivative unit kilodalton (kDa). Yeast proteins are on average 466 amino acids long and 53 kDa in mass.[5] The largest known proteins are the titins, a component of the muscle sarcomere, with a molecular mass of almost 3,000 kDa and a total length of almost 27,000 amino acids.[8]

care about atmosphere changes

care about atmosphere changes 

These days atmosphere is going to change we must take care of this situation we must use proper food and proper dressing. best way is we use orange more and more it is very good for our health and skin.