Friday, January 16, 2009
How Retrovirus Infect Organism?
Other common retrovirus targets include connective tissue cells, which form muscle, cartilage, or bone. On encountering a host cell, the retrovirus attaches itself to receptors on the surface of the host cell’s membrane.In this two-way process, the retrovirus’s glycoproteins and the host cell’s receptors bind together, locking the virus in place. The outer envelope of the retrovirus then fuses with the host cell membrane, enabling the viral capsid to enter the cell itself.
Once inside the cell, the capsid opens, releasing RNA and reverse transcriptase into the cell’s cytoplasm, a watery fluid that is rich in proteins and other chemicals. Using the cell’s chemical resources, reverse transcriptase builds up a double-stranded DNA molecule that mirrors the information stored in the viral RNA.
Initially, this DNA molecule is circular, but it is later spliced apart and inserted into the DNA of the host cell. From this moment onward, the viral DNA, known as a provirus, behaves like the host cell’s own genes.
The only difference is that the provirus contains instructions for assembling replicated viruses, rather than instructions for building or controlling a living cell.
As viral replication proceeds, the provirus directs the host cell to manufacture all the parts needed for more viruses, including capsids and viral RNA. These viral parts spontaneously self-assemble to form new viruses, and the new viruses migrate toward the exterior of the cell.
The newly formed viruses bud away from the host cell, taking with them small areas of the cell membrane, which the viruses use to form outer envelopes. The host cell may survive this viral breakout, but in many infections it becomes so weakened that it dies.
As viruses replicate and infect more cells, the number of cell deaths lead to tissue destruction and disease.
Retroviral disease
In other infections the retrovirus genes become incorporated into a host cell's DNA and enter a latent (dormant) state until some unknown agent or event triggers them to churn out new viruses.
In these cases, symptoms may not become apparent for months or even years after the initial infection.
Once installed, a retrovirus can damage host cells directly, or it can trigger cancer by disabling the systems that normally prevent cells from multiplying out of control.
Scientists first linked retroviruses to cancer in 1911, when American researcher Francis Peyton Rous investigated a form of tumor that occurs in chickens.
Rous passed a solution containing cells from these chicken tumors through a fine filter.The filter was intended to capture infectious agents, such as bacteria and protozoans.
Rous discovered that the filtered fluid from these tumors was still infectious, indicating the presence of an unknown infectious agent.He correctly concluded that a virus, which is so small that it passes through filters, was responsible for the chicken tumor.
Called Rous sarcoma virus, it was discovered many years later to be a member of the retrovirus family. Retroviruses also cause cancer in a range of mammals:
Cats and rodents are two well-studied examples.
In 1965, while studying the Rous sarcoma virus, American virologist Howard Temin made the surprising discovery that the virus’s RNA inserted its own genes into the DNA of the host cell.
In 1970 Temin and American molecular biologist David Baltimore, working independently, identified an RNA viral enzyme that copies genetic information to the host cell's DNA.
The enzyme later became known as reverse transcriptase.The discovery of reverse transcriptase shed new light on how a retrovirus changes a normal cell to a cancer cell.
The first human retrovirus was discovered in 1980. Known as human T-cell leukemia virus (HTLV), it exists in two forms, HTLV-I and HTLV-II, and appears to cause certain types of lymphoma (cancer of the lymphatic system) and leukemia.
In 1983 a third and quite different human retrovirus was discovered in patients suffering from a new immune deficiency disease (an illness that damages the immune system).
Initially labeled HTLV-III, it was renamed HIV in 1986 and has since gained worldwide notoriety as the cause of AIDS.HIV attacks the immune system of its host, undermining the very defenses that keep most viruses in check.
One group of immune system T cells, called CD4 cells, are particularly vulnerable to HIV and become primary targets soon after an infection begins.Initially, the amount of virus in the blood, known as the viral load, quickly climbs as newly replicated viruses are produced and released from host cells.
Following this stage, known as acute retroviral syndrome, the viral load drops, and it looks as though the immune system has brought the infection under control.Despite these promising signs, the virus is never completely eliminated.From its hiding place inside T cells themselves, HIV continues its attack, destroying T cells.
As T cells die, the immune system loses its ability to fight back.
Once the T-cell count drops below a critical level, microorganisms that are normally kept in check by a healthy immune system can reproduce at a rapid rate.
Without effective treatment, these opportunistic infections, rather than HIV itself, often have fatal results.
Retroviruses that cause immune deficiency diseases affect animals other than humans.
This group of retroviruses includes feline immunodeficiency virus (FIV), which infects cats, and simian immunodeficiency virus (SIV), which attacks monkeys and apes.
SIV is of particular interest in medicine as the origin of HIV. Scientists believe that SIV from a chimpanzee likely infected humans and underwent mutations to form HIV.
Scientists uses Retrovirus
Preventing the spread of the virus has proved a more difficult challenge.Despite intensive research, a vaccine against HIV still does not exist, largely because the virus mutates at such a rapid rate.
As a group, however, retroviruses may one day play a more positive role in human health. In gene therapy scientists use genetically altered viruses to insert beneficial genes into human cells.Once in place, these genes can potentially correct inherited disorders, such as cystic fibrosis. Retroviruses make suitable delivery vehicles because they have the chemical apparatus that is needed to splice genes into particular target cells.
Once the genes are inserted, they are copied and handed on each time the recipient cells divide.Gene therapy is still in its experimental stages, and where retroviruses are concerned, there are a number of practical problems to overcome.One of these involves the space where the genetic information of a retrovirus is stored.This space is small, which means that there is a limited amount of storage space for the beneficial genes that are to be transferred.
Another problem is safety, a prime consideration with agents associated with disease. Retroviruses used in gene therapy are genetically engineered to prevent them from replicating. However, there is still a slight possibility that these genetically engineered retroviruses may insert genes in an inappropriate region of DNA, triggering cancer or other problems.
In early 2003, the United States Food and Drug Administration (FDA) halted 27 gene therapy clinical trials that used a retrovirus to ferry genes into blood-producing cells.Two children involved in the trials became ill with a condition resembling leukemia, and the FDA decided it was unsafe to continue using this procedure.
Once safety problems can be overcome, however, the use of retroviruses in gene therapy may become a matter of routine.
Human Immunodeficiency Virus
HIV-1 is the primary cause of AIDS worldwide.HIV-2 is found mostly in West Africa.HIV belongs to the retrovirus family of viruses, whose members share a unique method of replicating themselves when they infect living cells.
Retroviruses store their genetic information in molecules of ribonucleic acid (RNA). However, unlike other RNA viruses, retroviruses use RNA as a template (master pattern) for forming deoxyribonucleic acid (DNA), the genetic material that puts viral replication instructions into effect.
This process, called reverse transcription, is the exact opposite of the normal flow of genetic information in living things, in which DNA serves as the template for RNA formation.HIV consists of a flexible outer membrane, called the envelope, that surrounds a protein case known as the capsid.
The envelope is studded with glycoproteins, chemical receptors that enable the virus to lock onto target cells.
Inside the capsid reside two identical strands of RNA.
These RNA strands make up the virus’s genetic program and store all the instructions needed to replicate HIV once it has infected a host cell.
HIV also contains molecules of an enzyme called reverse transcriptase.
When HIV infects a cell, reverse transcriptase copies the genetic instructions in the virus’s RNA and uses the instructions to build complementary strands of DNA.
HIV transmission occurs when a person is exposed to body fluids infected with the virus, such as blood, semen, vaginal secretions, and breast milk.
The primary modes of HIV transmission are
- (1) sexual relations with an infected person
- (2) sharing hypodermic needles or accidental pricking by a needle contaminated with infected blood
- (3) transfer of the virus from an infected mother to her baby during pregnancy, childbirth, or through breast-feeding.
When HIV enters the body, it infects lymphocytes, which are a type of white blood cell in the immune system.
HIV uses its glycoproteins to attach itself to receptors on the surface of a lymphocyte.
The outer envelope of HIV then fuses with the lymphocyte, enabling the HIV capsid to enter the lymphocyte itself.
HIV commandeers the genetic material of the lymphocyte, instructing the cell to replicate more viruses.
The newly formed viruses break free from the host, destroying the cell in the process. The new viruses go on to infect and destroy other lymphocytes.Over a period that may last from a few months to up to 15 years, HIV may destroy enough lymphocytes that the immune system becomes unable to function properly.
An infected person develops multiple life-threatening illnesses from infections that normally do not cause illnesses in people with a healthy immune system.
Some people who have HIV infection may not develop any of the clinical illnesses that define the full-blown disease of AIDS for ten years or more.
Doctors prefer to use the term AIDS for cases where a person has reached the final, life-threatening stage of HIV infection.
No treatment is available that cures AIDS, but a number of drugs have been developed that suppress HIV replication, thereby preventing the destruction of the immune system.
Known as antiretroviral therapy, these drugs target different stages in the life cycle of HIV. There are four main classes of drugs used against HIV: nucleoside analogues, non-nucleoside reverse transcriptase inhibitors, protease inhibitors, and fusion inhibitors.
Nucleoside analogues and non-nucleoside reverse transcriptase inhibitors use different mechanisms to block the action of the enzyme reverse transcriptase.
Protease inhibitors interfere with protease, an enzyme vital to the formation of new HIV. When these drugs block protease, defective HIV forms that is unable to infect new cells.
In 2003 the U.S. Food and Drug Administration approved the use of enfuvirtide, sold under the brand name Fuzeon.
This drug belongs to a new class of drugs called fusion inhibitors, which prevent the binding or fusion of HIV to lymphocytes.
The Immune system protects itself from infections
The Wasserman blood test for syphilis was developed in 1906 and the tuberculin skin test for tuberculosis appeared in 1908.
By the 1930s new techniques for growing viruses in the laboratory led to vaccines against viral diseases.
These included a yellow fever vaccine in the late 1930s and the first effective influenza vaccine in the 1940s. The American physician Jonas E. Salk developed a polio vaccine in 1954.
Later virologist Albert B. Sabin developed a safer oral polio vaccine, which was in wide use by the 1960s.
Later came vaccines for other childhood diseases, including measles, German measles, mumps, and chicken pox.
Simple tips can help
try this!! "COWS MILk+
EGGYOLK = MEDICINE "- 12 GLASS OF WATER /DAY----in 12 days 12
- 10 GLASS OF WATER/DAY------in 10 days 10
- 8 GLASS OF WATER/day -----regular day 8
To help our Immune System.
Immune System, group of cells, molecules, and organs that act together to defend the body against foreign invaders that may cause disease;
- bacteria
- viruses
- fungi.
Breath odor as a clue to health problem
Collecting a breath sample and analyzing it, useful in medicine to diagnose certain conditions, and also used by the police to measure alcohol consumption.Since the time of Hippocrates in ancient Greece doctors have been aware that the odor of a patient's breath can aid diagnosis.
For example, the breath of a person with kidney failure smells similar to urine, and an undiagnosed diabetic's breath has a fruity odor.In 1784 French scientists Antoine Lavoisier and Pierre Simon Laplace analyzed the breath of a guinea pig to reveal that it consumed oxygen and exhaled carbon dioxide.
Many breath tests require the patient to consume a substance beforehand, with the test checking for the broken down products of this substance.Abnormal quantities of the broken down product indicate disease.
For example, before a breath test to diagnose malabsorption syndrome (a condition characterized by severe, chronic diarrhea caused by the small intestine failing to absorb food efficiently) the patient must eat a dose of xylose, a sugar normally completely absorbed in the intestine.Large amounts of hydrogen in the breath within the next few hours reveal the disease is present. Research into using an electronic "nose" to analyze patients' breath began in Britain in 1995.
Blood alcohol level
Forensic science uses sophisticated laboratory techniques to detect the presence of substances in the victim, in the suspected criminal, or at the crime scene.
For example, in determining whether alcohol was involved in a crime, the amount of alcohol in the blood can be measured in two ways.
One is to measure the amount of alcohol exhaled in the breath of an individual, which reveals the concentration of alcohol in the person's blood.Recent advances in technology have produced alcohol breath-testing instruments so accurate that their results are evidential (capable of providing evidence in court).
Blood-alcohol level can also be determined by actual blood tests, usually through gas chromatography.In this method, the blood sample is vaporized by high temperature, and the gas is then sent through a column that separates the various chemical compounds present in the blood.
Gas chromatography permits the detection not only of alcohol but also of other drugs, such as barbiturates, cocaine, amphetamines, and heroin.
Ayurvedic Medicine
Ayurveda does not seek to treat the symptoms of disease; instead, it seeks to restore the underlying balance of the doshas.The Ayurvedic practitioner diagnoses a patient’s constitutional type and imbalances through such techniques as questioning;
a. specialized pulse measurementsb. observation of the tonguec. eyesd. nailse. face and skinf. voice qualityg. urineh. breath odor.The practitioner then makes specific recommendations to bring the doshas back into balance.
What causes Bad breath?
Halitosis, foul-smelling breath.
Could it be your breath?
Maybe you shouldn't have put extra onions on your hamburger at lunch.
The good news is that bad breath happens to everyone once in a while. Let's find out how to detect it, prevent it, and even treat it.
What's That Smell?
Bad breath is the common name for the medical condition known as halitosis .Many different things can cause halitosis — from not brushing your teeth to certain medical conditions.
Sometimes, a person's bad breath can blow you away — and he or she may not realize there's a problem.There are tactful (nice) ways of letting someone know about bad breath.You could offer mints or sugarless gum without having to say anything.
If you need to tell a friend he or she has bad breath, you could say that you understand foods can cause bad breath because you've had it before yourself.
By letting someone know that bad breath isn't something unusual, you'll make the person feel more comfortable and less embarrassed about accepting your piece of chewing gum.
If you suspect your own breath is foul, ask someone who will give you an honest answer without making fun of you.
(Just don't ask your brother or sister — they just might tell you your breath stinks even when it doesn't!)
Although everyone gets bad breath sometimes, if you have bad breath a lot, you may need to visit your dentist or doctor.
What Causes Bad Breath?
Here are three common causes of bad breath:a. foods and drinksb. garlicc. onionsd. cheesee. orange juicef. soda
Poor dental hygiene
Meaning you don't brush and floss as you shouldsmoking and other tobacco use
Poor oral hygiene
Leads to bad breath because when you leave food particles in your mouth, these pieces of food can rot and start to smell.
The food particles may begin to collect bacteria, which can be smelly, too.Plus, by not brushing your teeth regularly, plaque (a sticky, colorless film) builds up on your teeth.
Plaque
Is a great place for bacteria to live and yet another reason why breath can turn foul.Preventing Smelly Breath
Don't smoke or use tobacco products
And take care of your mouth by brushing your teeth at least twice a day and flossing once a day.Brush your tongue, too, because bacteria can grow there. Flossing once a day helps get rid of particles wedged between your teeth. Also, visit your dentist twice a year for regular checkups and cleanings.Not only will you get a thorough cleaning, the dentist will look around your mouth for any potential problems, including those that can affect breath.
For example,
Gum disease
Also known as periodontal disease, can cause bad breath and damage your teeth.
If you're concerned about bad breath, tell your doctor or dentist.But don't be surprised if he or she leans in and take a big whiff! Smell is one way doctors and dentists can help figure out what's causing the problem.
The way a person's breath smells can be a clue to what's wrong.
For instance, if someone has uncontrolled diabetes, his or her breath might smell like acetone
(the same stuff that's in nail polish remover).
If you have bad breath all the time and the reason can't be determined by your dentist, he or she may refer you to a doctor to make sure there is no other medical condition that could be causing it.
Sometimes sinus problems
And rarely liver or kidney problems, can cause bad breath.Usually, there's a less complicated reason for a kid's bad breath — like what you had for lunch.So keep up with your brushing and flossing and you should be breathing easy — and odor free!
Diseases and Disorders of the Mouth
Infectious disease of horses, cattle, swine, and humans, also called lumpy jaw or big jaw.
It is caused by several species of bacteria of the genus Actinomyces .In humans it is caused mainly by Actinomyces israelii, a component of the normal flora of the mouth and tonsillar crypts.
The bacteria invade decayed teethdiseased tonsilssoft mouth tissues
The disease is characterized chiefly by abscessed, swollen, and lumpy tissues of the jaw.The lungs and intestinal tract may also become infected.It is treated by draining abscessed tissues and by using large doses of penicillin or tetracycline.
b. Canker Sore
Small sore on the inside of the lips or cheeks, or on any other part of the mouth that is coated with mucus.
Usually invisible when the mouth is closed, canker sores are small blisters that rupture and become painful, whitish-yellow ulcers.
Although the sores may develop singly, they usually appear in groups of fewer than five, and they tend to heal in about ten days.
Outbreaks involving more than ten small sores at a time are not unknown, however.
Fever and fatigue may accompany these larger outbreaks, which can take up to three months to heal and result in scarring.
The precise cause of canker sores is unknown, but they often result from oral irritation, injury, or viral infection, and are also associated with acute emotional stress and with various kinds of allergies.
In addition, the sores have been linked to dietary deficiencies of iron, vitamin B12, and folic acid.
Although not caused by bacterial infection, canker sores provide breeding grounds for bacteria that make the sores take longer to heal and cause more pain.
Most people will suffer from canker sores at some time in their lives; men have a lower rate of incidence than women.
Most canker sores heal on their own, and no special treatment will speed the process.
Mild pain-killing and anti-inflammatory ointments and mouthwashes provide some relief for people with recurring canker sores.
c. Cold Sore
Also called fever blister, a small, painful blister on the face, especially around the lips and nose and inside the mouth.
A cold sore first appears as a small red pimple that gradually develops into a small, painful blister full of clear fluid.
When the blister ruptures, it appears yellowish, dry, and crusted.
Cold sores are caused by a herpes simplex virus.
They spread from one individual to another by direct contact between skin surfaces, and they usually erupt in clusters.
Most people infected by the herpes simplex virus contract it before adolescence, but only a small percent of exposed children actually develop symptoms at that time.
When the herpes simplex virus is inactive, it lies dormant in neurons, or nerve cells.
Later, illnesses or emotional upsets can reactivate the virus and trigger the development of cold sores, and affected individuals often suffer from recurring attacks.
Cold sores tend to accompany common colds and infectious diseases, such as pneumonia and diphtheria, that are characterized by fever.
The cold sore infection itself can raise body temperature above normal and account for swelling in the lymph nodes of the neck.
Cold sores usually last from ten days to two weeks, and no preventive measures are known, although complications caused by the bacterial infections that often accompany cold sores can be controlled by antibiotic ointments.
The antiviral ointments known as vidarabine and acyclovir may also be prescribed to relieve the pain of cold sores.
Life Practical Suggestions
by: Psychologist Sonja Lyubomirsky University of California
1. Count your blessing;=Once a week write down three to five things that you are thankful for.
2. Practice acts of kindness;=Being kind to others makes you feel generous and capable, and gives you a sense of connection with others.
3. Savours life's joys;=The warmth of the sun or the beauty of nature. Take menthal photographs of pleasurably experiences to reflect on in less happy times.4. Thank a mentor=Someone to whom you owe your gratitude for their guidance during a challenging time.
5. Lear to forgive=Let go of anger and resentment. Write a letter of forgiveness to someone that has wronged you.
6. Invest time and energy into friends and family;=Personal relationships are the biggest factor in your own satifaction with your life.7. Take care of your body;=Get plenty of sleep, exercise, smiles and laughter.
8. Develop strategies for coping with stress and hardships;=The belief that hardtimes will pass and things will get better.Cold Symptoms
Acute viral nasopharyngitis, or acute coryza, usually known as the common cold, is a highly contagious, viral infectious disease of the upper respiratory system, primarily caused by picornaviruses (including rhinoviruses) or coronaviruses.Common symptoms are sore throat, runny nose, nasal congestion, sneezing and coughing; sometimes accompanied by 'pink eye', muscle aches, fatigue, malaise, headaches, muscle weakness, and loss of appetite. Fever and extreme exhaustion are more usual in influenza. The symptoms of a cold usually resolve after about one week, but can last up to two. Symptoms may be more severe in infants and young children. Although the disease is generally mild and self-limiting, patients with common colds often seek professional medical help, use over-the-counter drugs, and may miss school or work days. The annual cumulative societal cost of the common cold in developed countries is considerable in terms of money spent on remedies, and hours of lost productivity.
The primary method to prevent infection is hand-washing to minimize person-to-person transmission of the virus. There are no antiviral drugs approved to treat or cure the infection. Most available medications are palliative and treat symptoms only. Megadoses of vitamin C, preparations from echinacea, and zinc gluconate have been studied as treatments for the common cold, but none have been approved by the Food and Drug Administration or European Medicines Agency.