INDEX viral infections

Theophylline is a narrow therapeutic index drug with significant difference in bioavailability following oral administration. The half-life of the drug is increased by heart failure, cirrhosis and viral infections, in elderly patients, and by certain drugs, such as cimetidine, ciprofloxacin, oral contraceptives and fluvoxamine. The half-life is decreased in smokers, chronic alcoholism, and by certain drugs, such as phenytoin, rifampicin and carbamazepine. 

Antiviral activity. Epigallocatechin-3-gal-late, administered to Hep2 cells in culture, produced a therapeutic index of 22 and an ICjf, of 25 pM. The agent was the most effective when added to the cells during the transition from the early to the late phase of viral infection suggesting that the polyphenol inhibits one or more late steps in virus infection " . 

Despite its lack of specificity, Bik determination has been shown to correlate well (p < 0.01) with other indexes of inflammation, including C-reactive protein (CRP), WBC count, and erythrocyte sedimentation rate (ESR) [4]. The urine strip is an alternative to a blood CRP measurement. The Bik test was more predictive of upper respiratory and urinary tract infections as well as kidney diseases. Furthermore, it was more sensitive to bacterial and viral infection vs CRP. Because plasma proteins, that is CRP, are not cleared and circulate until hepatic metabolism, urinary Bik appears to be a better predictor of an abnormal WBC, ESR, and neutrophil degranulation. 

HIV infection occurs through three primary modes of transmission sexual, parenteral, and perinatal. The most common method for transmission is receptive anal and vaginal intercourse, with the probability of transmission up to 3% per sexual contact for the former, and up to 0.2% per sexual contact for the latter. The probability of transmission increases when the index partner has a high level of viral replication (which occurs at the very beginning of infection or late in disease), or when the uninfected partner has ulcerative disease, compromised mucosal surfaces, or (in the case of men) has not been circumcised. 

Smallpox spread slower than other viral rash illnesses like chickenpox and measles. When smallpox still occurred naturally, most people who became infected were close contacts of an index case, snch as household members, close friends and health care workers. Honsehold secondary attack rates were typically 50-60% (25). Larger ontbreaks in schools were nncommon. Two reasons for this are that that transmission did not occnr before rash onset and that the disease caused severe incapacitation. By the time of rash onset, victims were so ill that they did not attend school or go to other commnnity events where they might have exposed others. Secondary cases typically occnrred in hospital and household contacts. 

Acyclovir 4,19) is undoubtedly the most interesting of the known anti-viral drugs because of its.high therapeutic index. It is, for example, 3000 times more toxic to herpes simplex virus than to mammalian cells. Somewhat like amino-idoxuridine 4,14b), acyclovir is monophosphorylated by a virus-specified thymidine kinase and then converted to the triphosphoryl derivative which injures the virus by competing, against deoxyguanosine triphosphate, for the virus-specified DNA polymerase in the infected cells (Fyfe et al, 1978). This inhibition puts an end to all DNA synthesis in these cells. Its phosphorylation does not take place in healthy cells, which are thereby spared, and this accounts for most of the selectivity. For the rest the DNA polymerase of infected cells is more sensitive to acyclovir triphosphate than is the DNA polymerase of healthy mammalian cells which, in any case, receive very little of this product (Elion, 1980). 

The antiviral activities of the test compounds/extracts are measured with the CPE inhibition assay (Liu et al. 2008b). Viral suspension (200 TCIDj ml, 100 pi) is added to each well of a 96-well plate containing a confluent cell monolayer. After incubation at 37°C for 2 h, the virus solution is removed, and 100 pi of consecutive threefold serial dilutions of the test compounds/extracts and reference compounds are added to each well, using the MNCC as the highest concentration. An infection control without samples is also included. The plates are incubated at 37°C in a humidified CO atmosphere (5% CO ) for 24 h, after which the CPE is assessed. The virus-induced CPE is scored as follows 0=no CPE, 1=0-25% CPE, 2=25-50% CPE, 3 = 50-75% CPE, and 4 = 75-100% CPE. The reduction in virus multiplication is calculated as a percentage of the virus control (% virus control = CPE Z 100). The IC, of the CPE with respect to the virus control is estimated using the Reed-Muench method. The selective index (SI) is calculated as the ratio CC /IC... 

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