HERP index

Davis (1989, 332-33) also argues that neither the HERP index nor, implicitly, an analogue developed from the TI rather than the TD50 measure can account for... 

Although one cannot say whether the ranked chemical exposures are likely to be of major or minor importance in human cancer, it is not prudent to focus attention on risks at the bottom of a ranking if the same methodology identifies numerous, common human exposures that pose much greater possible risks. Our rankings are based on the human exposure/rodent potency (HERP) index, which is the ratio between the average human exposure to a chemical and the dose that caused cancer in 50 percent of exposed rodents. 

A detailed examination of HERP-index did not provide the possibility to conclude that the risk of exposure to industrial carcinogens and pesticides outside the workplace are trivial compared with those of naturally occurring carcinogens found mostly in the diet... 

While qualitatively useful the HERP index does not take into account impotant interactions among naturally occurring and synthetic constituents in foods, nor does it permit examination of the possible role of evolved resistance. But the pqiers of Ames and co-authors pay attention to the problem of carcinogenicity of natural chemicals which have not yet been investigated. 

An increased IgA index is found in aseptic meningitis in 40% of cases and in herpes encephalitis in almost 100% of cases as a result of virus-specific IgA antibody production. In neuromberculosis, an increased IgA index is often accompanied by normal IgC and IgM indices (LI). 

In 1965, the FDA banned investigation in humans of dimethyl sulfoxide owing to the appearance of changes in the refractive index of the lens of the eye in experimental animals. However, in 1966, the FDA allowed the study of dimethyl sulfoxide in serious conditions such as scleroderma, persistent herpes zoster, and severe rheumatoid arthritis, and in 1968 permitted studies using short-term topical application of the solvent. By 1980, the FDA no longer specifically regulated investigations of dimethyl sulfoxide. ... 

Fluoroidoaracystosine (FIAC, Fig. 7-16) is a potent and selective inhibitor of herpes viruses. Like acyclovir and BVDU, it, too, must be phosphorylated by viral thymidine kinase to act. Its selectivity toward the viral enzyme is several thousand times higher so that it is active against HSV-1 and -2 and herpes zoster virus (HZV) with a good therapeutic index. Clinical studies seem promising. 

Vidarabine 4.16) differs from adenosine in the same way that cytarabine differs from cytidine, namely the natural sugar has been replaced by arabinose. However, the anti-viral properties of vidarabine are more to the fore than any anti-cancer power, the exact opposite of cytarabine s properties. Vidarabine, also known as Ara A, is 9-j8-D-arabinofuranosyladenine and it has a reasonably high therapeutic index (Muller et al., 1977). Its most successful and spectacular application has been in herpes virus encephalitis, of which several thousands of cases break out in the United States each year, killing 70% of the sufferers... 

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). 

Fig. 8.2. A. B. Ex vivo antigen-specific proliferation of peripheral blood mononuclear cells (PBMC) isolated on day 25 post-withdrawal of CLA from the diet. Pigs had been fed either a control diet (left) or a CLA-supplemented diet (right) for 72 days. PBMC were cultured for 5 days with spirochetal antigens (B. hyodysenteriae), viral antigens (pseudorabies virus a relative of herpes simplex virus) or both. Data represents the mean stimulation index of cells in a lymphocyte blastogenesis assay based on incorporation of methyl-[3H] thymidine. Pigs were immunized on days 0 and 20. Significant differences (P < 0.05) caused by the interaction between vaccine and diet are shown with the (yen) sign.

All essential oils from anise, hyssop, thyme, ginger, camomile and sandalwood possess virucidal activity against HSV-2 mainly before adsorption probably by interacting with the viral envelope (Koch et al. 2008). Camomile oil exhibited a high selectivity index and seems to be a promising candidate for topical therapeutic application as virucidal agents for treatment of herpes genitalis (Koch et al. 2008). 

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