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Cellular effects can cause illness in an individual infected with A virus

Tia

A range of effects on host cells that can be caused by a virus fall into several categories.

Some viruses do not produce pathological detriment - these infections are asymptomatic.

Some viruses, e.g. picornaviruses, described as cytocidal, quickly kill their host cell - releasing. Non-cytocidal viruses replicate and release their progeny without killing the host cell immediately, e.g. influenza, or even at all, like herpes virus. Cytocidal and non-cytocidal viruses both cause acute infections in their hosts.

Sometimes a virus will infect a cell, produce few or no progeny, and the host cell remains largely intact. This type of viral infection is described as persistent e.g. the HIV virus.

Viruses usually produce harmful effects. These alterations in host cells/tissues are described as cytopathic effects-they may appear rounded up, or their nuclei may be swollen, and some cells may even fuse to form giant cells called syncytia.

An infected cells metabolism is corrupted and they can often no longer synthesize protein Pathogenic viruses, especially, cytocidal ones, produce factors that inhibit the synthesis of host DNA, RNA and protein, like the polio virus, which produces proteins known as 2A and 3C that inhibit host cell translation and transcription respectively.

It is not completely known how these viruses kill their host cell as they die before they have exhausted their protein supplies. It could be that the integrity of the plasma membrane is compromised.

Damage to the plasma membrane may lead to the death of the host cell. This is because different concentrations of Na+ions and K+ions inside and outside the cell may no longer be maintained, and dissipation of these ion gradients can have consequences

i.e. osmotic lysis. Infected cells are often found to have viral proteins in their plasma membranes. The immune system recognises them as foreign antigens, and responds accordingly. Alterations to the membranes of a group of infected cells can lead to the membranes fusing to form a giant, multinucleate cell (the syncytia seen in culture). Such cells are observed in measles and HN infections, where upto 50 or 100 cells can conglumerate.

Viruses can also damage intracellular membranes e.g. those of lysosomes, allowing the egradative anzymes to leak out, leading to self-digestion and consequent lysis.

The granules of inclusion bodies consist of sites where new viral components are being synthesized. These sites may be found in the cytosol or the nucleus, depending on the virus involved, and can detriment the cell's ultrastructure.

Poxviruses form inclusion bodies in the cytoplasm, whereas the measles virus forms them in both the cytoplasm and the nucleus. Adenoviruses are assembled in the nucleus. The newly synthesised viral components often pack together to form a crystal-like structure known as a paracrystal line array.

Viruses that penetrate the cell nucleus, e.g adenoviruses and herpes viruses, may disrupt the chromosomes.

Viral replication needs a living/functioning cell, so the host cell is not killed until the progeny have been produced. But, it is in the host's interest that the virally infected cell should die immediately.

Apoptosis-programmed cell death - is thus an important mechanism of host defence, and is demonstrated by cells infected with viruses such as HIV, influenza and picomaviruses. Viruses, though, have evolved their counterstrategies.

Many viral proteins are toxic to the host, because of high concentrations or they may have a morphological change. An example of this is the gp120 viral envelope protein of HIV, which triggers apoptosis in neurons by altering the intracellular concentration of calcium ions.

Cellular effects can cause illness in an individual infected with a virus. Numerous viruses cause acute infections leading to a rapid onset of symptoms followed by recovery, and complete elimination of the virus from the body.

Conversely, viruses can cause persistent infections, here the virus stays in the host for an extended period. They stop any cytopathic activity and successfully invade the immune system. Some viruses adapt both strategies: Varicella zoster, the herpesvirus that causes chickenpox, also causes a type of persistent infection described as latent.

Concluding the acute chickenpox infection, the virus persists in the sensory nerves without replicating and is undetectable i.e. latent. Years later, the virus can reactivate, on several occasions, to produce the skin disease shingles.

Another type of persistent infection is called a slow infection, because following an initial acute stage, the virus eventually brings about symptoms that kill the host e.g. subacute sclerosing panencephalitis, which may be caused by the measles virus.

Some infections with DNA viruses or retroviruses can detriment a cell by altering its behaviour. Transformation is sometimes affiliated with integration of viral nucleic acid into the host genome, disturbing the genetic sequence, so lacking the regulatory mechanisms and may grow quicker than its neighbours. These cells can cause cancer e.g. some types of cervical cancer have been linked with certain papilloma viruses.

Medicine at our doorsteps: Tejpat

-Jamayet Ali

Tejpat is a medium-sized evergreen tree with fragrant oblong lanceolate leaves, occasionally planted in gardens for its leaves in many places. But the leaves which constitute the actual drug, are readily available as a commercial commodity everywhere in the country. The plants are raised from seeds sown in nursery beds in March-April. Seedlings appear 30-45 days after sowing and are transplanted when 4-5 years old. Sufficient shade is provided in the early stages of growth and shade trees are cleared after 8-9 years. The fields are not usually manured; under-growth in occasionally removed. The leaves are ready for harvesting when the trees become 10 years old, and they continue to bear for a century. The leaves are collected every year from young plants and in alternate years from old and weak ones. Collections are made in dry weather from October to till March. Continuous rain diminishes the aroma of the leaves. Small branches with leaves are dried in the sun for 3 or 4 days and tied up into bundles for collection.

Botanical name of Tejpat is Cinnammomum Tamala. The tree is cultivated in all districts of the country. It is also found wild in Tropical and subtropical Himalaya, 3000-7800 ft., Sylhet and Khasia hills, 3000 - 4000 ft. The leaves are commonly used as a condiment, but they are also employed in calico-printing in combination with marabolans. The outer bark of the plant yields on distillation an essential oil. It is chiefly used in the manufacture of soap, especially what is called Military soap. The oil from bark contains cinnamaldehyde (70-85 %) as a major constituent. The leaves are mainly used as spice. The dried leaves act as anti-oxidant to oils and fats.

Medicinal Properties: The leaf is bitter, sweetish; heating, alexiteric; useful in "vata", scabies, diseases of the anus and rectum, "tridosha", piles, heart troubles, ozoena, bad taste (Ayurveda). The leaf has a sharp taste; tonic to the brain, anthelmintic, diuretic; good for the liver and spleen; useful in inflammation, sore eyes; stops salivation (Yunani). In the Punjab, the leaves are used in rheumatism, being considered stimulant; also in colic and diarrhoea. The bark is given for gonorrhoea. Given in decoction or powder in suppression of lochia after child-birth, with much benefit. The oil from the bark is ineffective as an anthelmintic. The leaves are not an antidote to either snakevenom or to scorpion-venom. (Indian Medicinal Plants, K.R. Kirtikar & B.D. Basu, Vol. Ill, 2146-47)

Medicine: The bark is given for gonorrhoea, and the leaves are used in rheumatism as a stimulant. The latter "are supposed to have furnished the Folia malabathri. They are held in considerable repute by the ancients for their stomachic and sudorific properties. They partake of the aroma and pungency, and probably also of the carminative properties, of cinnamon." They are used in flatulent colic, diarrhoea and other diseases arising from the disordered state of the bowels. They resemble cloves closely in medicinal properties, for which they may be substituted. Baden Powel Powell says that the leaves are considered by the natives hot and cardiac, and that they are useful in colic, indigestion, and nausea. The bark is prescribed by the hakims in debility of the stomach, enlargement of the spleen, affections of the nerves or heart, pains in the womb, also in retention of urine and catamenia, and bites of serpents and poisoning by opium. An aromatic oil extracted from the fruit and leaves is used as a medicine.

Special Opinions: "The leaves in Kashmir, Barg-i-Taj, are employed as a substitute for Chavica Betle, Retz" (Surgeon-Major J.E.T. Aitchison, Simla). "Dalchini, used in dispensary in place of true cinnamon; equally efficacious" (Assistant Surgeon Nehal Sing, Saharunpore). "Used with long-pepper and honey in coughs and colds, also in bronchitis and hayasthma" (Brigade Surgeon J.H. Thornton, Monghyr). "Given in decoction or powder in suppression of lochia after child-birth, with much benefit" (Surgeon Major J.J.L. Ratton, Salem) "Is used in coughs, flatulence, and fevers" (Surgeon Major D.R. Thomson, Madras). (Dictionary of the Economic Products of India, Watt, Vol. II, 321, 322)

Properties and uses: Leaves are carminative, stimulant, diuretic, diaphoretic, lactagogue and aromatic. They are used in the treatment of colic, diarrhoea, anoerexia, skin diseases, sore throat, coughs and colds. The leaves show antibacterial anti fungal activities. They are also used for treating scorpion-sting. The leaves also possess hypoglycaemic properties. Ethanolic extract of the leaves significantly lowers plasma glucose level and exhibits anti-hypercholesterolemic and anti-hypertriglyceridemic effects in hyperglycemic rats. Being effective diuretic and emmenagogue the leaves are applied over the stomach and lower regions to bring about urine and menses. The bark is used in the treatment of gonorrhoea. It also acts as a carminative. Leaves and bark mixed with tea cures coughs and colds. Essential oil exhibits anti bacterial and anti fungal activities. (Medicinal Plants of Bangladesh, Abdul Ghani, Second Edition, 164)

Medicinal values: The leaves are carminative, and are used in colic, diarrhoea and rheumatism. They are considered hot and cardiac and are used with long pepper and honey in cough and cold. The leaf powder is reported to have distinct hypoglycaemic action.

Two teaspoonfuls of the powder given to diabetic patients four times a day for one month, accompanied by controlled diet, significantly reduces the blood sugar level and helps in release or manufacture of more insuline. The bark is aromatic. It is coarser than the bark of true cinnamon and is one of its common adulterants. It is carminative and is also given for gonorrhoea (Wealth of India, Raw Materials, Vol. III, 581).

Information about Malaria

Name and type of causative organism: Malaria is caused by the protozoan (single-celled, protoctists that have animal-like cells that are not able to photosynthesize) parasites of the genus Plasmodium (of the phylum Apicomplexa).

Is it a newly evolved disease? No. It has probably afflicted humans throughout our evolutionary history, but the first historical reports of symptoms that match those of malaria date back to the ancient Egyptians (around 1550 B.C.) and the ancient Greeks (around 413 B.C.).

Number of deaths per year worldwide: Approximately 1.3 - 2 million.

Symptoms: Fever, shivering, arthralgia, vomiting, anaemia caused by haemolysis, haemoglobinuria, and convulsions. Additional complications include coma and death if not treated properly. Children and pregnant women are more vulnerable.

Feature: Malaria: Route of transmission: It is transmitted by biting. When the Anopheles mosquito sucks blood it injects saliva. If the blood sucked in contains malarial parasites- they undergo reproduction in its salivary glands. If these mosquitoes mouth parts pierce a healthy person, saliva containing parasites is injected into the bloodstream and he/she may develop malaria

Reservoir of infection: The transmission vector for human malarial parasite is the female Anopheles mosquito.

Type of cells affected : Red blood cells ( erythrocytes)

Time course : Symptoms initiate after an incubation period of 10 to 14 days after the infective bite, during which the parasite inhabits the liver and disease then reproduces in the blood. Fever usually recurs every few days, in accordance with the erythrocytic cycle. Every time the infected cells burst, new merozoites, toxic metabolites and malarial antigens are released.

The immune system responds with a fever.

What treatment is available? Anti-malarial drugs:

Quinine (Therapy only)

Chloroquine (Therapy and prophylaxis; usefulness now reduced due to resistance)

Sulfadoxine- pyrimethamine (Therapy; prophylaxis for semi-immune pregnant women in endemic countries as "Intermittent Preventive Treatment" - IPT)

Is a vaccine available : No vaccination yet.

Germans seek China tie to blood thinner heparin

Carter Dougherty

The German authorities said Friday that they had asked all German producers of the blood thinner heparin to check whether their ingredients came from China, after allergic reactions to the drug there were linked to two Chinese suppliers.

In cases where China did supply the raw ingredient, manufacturers were asked to test for any irregularities. The German authorities recalled the suspect heparin on Wednesday after receiving reports of allergic reactions in about 80 patients.

Heparin manufactured with Chinese ingredients has been linked to 19 deaths in the United States. Federal drug regulators there said sophisticated tests had found what might be a counterfeit ingredient in the heparin associated with the deaths and serious allergic reactions in more than 700 patients.

That unknown substance mimics real heparin and was found in concentrations of up to 20 percent in some of the suspect drug, according to the United States Food and Drug Administration. But the agency said it had not yet established whether the contaminant was responsible for the allergic reactions.

The suspect heparin in the United States was made by Baxter International, with ingredients from a Chinese company called Changzhou SPL. The discovery that the ingredients for the German-made heparin came from two different Chinese plants has led investigators to suspect that the problem may lie farther back in the supply chain.

The German authorities identified the two plants as Changzhou Quianhong Bio Pharma Company, and the Yantai Dongcheng Biochemicals Company. Both are among the top 10 Chinese exporters of heparin, according to a report last September by the China Chamber of Commerce for the Import and Export of Medicines and Health Products. Officials in the sales departments of both Chinese companies said Friday that they were unaware of the problems in Germany.

The suspect heparin was manufactured by Rotexmedica, a subsidiary of the French company Groupe Panpharma. Rotexmedica, based in Trittau in northern Germany, said Friday that it would not comment on the recall because its executives were busy consulting with regulators. Rotexmedica has issued a worldwide recall for its heparin-containing products, which are mostly exported from Germany, said Ulrich Hagemann, an official in the pharmaceutical safety department of the Federal Institute for Drugs and Medical Devices.

The European Medicines Agency, which is based in Britain, has looked through databases in Europe and concluded that there had been no allergic reactions to heparin in any European countries except Germany.

He said the reactions in Germany were far less severe than those in the United States, and had been traced to three specific batches of heparin produced by Rotexmedica. Those batches as well as other batches containing raw materials from the same sources were recalled March 5, and there have been no other patient reactions since.

Heparin is an injectable blood thinner given to prevent and treat blood clots. It is also used in kidney dialysis and open heart surgery. Adverse reactions have included lowered blood pressure, shortness of breath and an elevated heart rate.

The German authorities first got word of a possible problem on Feb. 14, Mr. Hagemann said, when three hospitals reported that three patients had “severe allergic reactions” to a heparin-containing product. Since allergic responses to these medicines are known to happen from time to time, this information alone was not enough to trigger a recall.

But toward the end of last week a group that provides home kidney dialysis told regulators that 80 people had suffered reactions to the products. Subsequent analysis of the reports suggested that not every patient was having a reaction to heparin-linked products, Mr. Hagemann said, but the initial information was enough to start the recall.

“At that point, we had to look at all heparin-containing products of Rotexmedica,” he said. A separate heparin-containing product produced by Rotexmedica, which is more finely processed, appears not to be affected, he added.

Although the German firm has no link to Baxter, those German batches are now being analyzed to see if they have the same chemical impurity as the contaminated Baxter heparin in the United States, Mr. Hagemann said. The German federal agency is still waiting for reports from state health authorities on whether any companies in their jurisdictions purchased active ingredients from China.

Much of the world’s heparin originates in China, where the raw material for the drug is gathered from pigs. In the first half of last year, China exported heparin to 42 countries and regions, according to Chinese officials. China exported the most heparin, about 13 tons, to Germany.

(Carter Dougherty reported from Frankfurt, and Elisabeth Rosenthal from Rome. Walt Bogdanich contributed reporting from New York, and Jake Hooker from Beijing.)