Siraj I. Mufti

Functional and numerical alterations induced by ethanol in the cellular immune system.

Ethanol was found to alter functioning and numbers of lymphoid cells of the cellular immune system in humans and rats. In in-vitro studies on human lymphocytes, a higher than 0.1% concentration of ethanol and acetaldehyde and acetic acid, the metabolites of ethanol, caused a decrease in the formation of E-rosettes. Methanol and propanol also resulted in a decrease in E-rosette formation. The natural killer (NK) cells varied in their ability to lyse tumor cells. In vitro, the NK-cell activity declined at higher than 0.2% concentration of ethanol. The NK activity in cells isolated from spleen and thymus of rats fed 1 g/dl or 7 g/dl ethanol did not differ significantly from the controls. Sprague Dawley rats fed 1 g/dl or 7 g/dl ethanol for 12 weeks had a significantly smaller thymus compared to the controls. Alveolar macrophages isolated from the rats exhibited impaired phagocytic activity. In agreement with other investigators, ethanol was found to result in a loss of T-cell population in the spleens of rats fed ethanol for 13 months. On the other hand, the T-helper cells and the proportion of T-helper to T-suppressor cells were found to increase in the splenocytes from these rats. This latter occurrence, apparently, is to compensate for the general loss of T-cell population observed in the body that occurs with ethanol ingestion. It is hypothesized that immunosuppression and the transient imbalances in the components of the cellular immunity induced by ethanol lead to an increased risk of pathogenesis associated with alcohol consumption.

Vitamin E reduction of lipid peroxidation products in rats fed cod liver oil and ethanol

The purpose of this study was to investigate the effects of vitamin E supplementation on ethanol- and cod liver oil-induced lipid peroxidation. Adult male rats received diets containing ethanol, cod liver oil and supplemented with vitamin E for 28 days. Following treatment, hepatic conjugated dienes, lipid fluorescence, and exhalation of ethane were measured as indices of lipid peroxidation. Ethane expiration over a 3-hour period was reduced by 96% in rats fed ethanol supplemented with vitamin E. Exhalation of ethane was increased by CLO feeding but was reduced 89% in the CLO-fed rats supplemented with vitamin E. In addition, ethane production was elevated in rats fed ethanol plus CLO compared to rats fed diets containing CLO supplemented with vitamin E. Supplementation of the CLO diet with vitamin E also significantly decreased hepatic conjugated fatty acid dienes levels. Levels of hepatic conjugated fatty acid dienes from rats fed ethanol plus vitamin E were reduced 91% compared to rats fed ethanol diets. Additionally, hepatic lipid fluorescence expressed as per mg of hepatic phospholipid basis was also significantly increased in rat groups fed vitamin E, ethanol, and cod liver oil diets. Where vitamin E was added to these same diets a significant decrease of hepatic lipid peroxidation products occurred. The observed reduction in lipid peroxidation by vitamin E may be useful to retard lipid peroxides derived materials involved in the development of alcoholic liver diseases.

Alcohol, cancer, and immunomodulation

There is a great deal of epidemiological evidence indicating that chronic, excessive alcohol consumption is a major risk factor for cancers in humans. However, the experimental basis for the increased cancer risk associated with alcohol intake is not clear. Since it appears that ethanol alone is not carcinogenic, ethanol effects must be explained in terms of its modifying the actions of other causal agents. Current studies indicate that ethanol and its congeners may act as tumor promoters, thereby enhancing the effect of initiating carcinogens from the environment. Available evidence also shows that ethanol is immunosuppressive. Clearly, cirrhosis due to high, prolonged alcohol intake is an indicator of the immunosuppressive effects of ethanol. It is less clear that more moderate intakes of alcohol could have as profound an effect on immune systems. However, changes do occur yielding alterations in lymphocyte sensitivity to alcohol in vitro and in cell development, as shown by increased NK cell function at low concentrations. Since other conditions, such as cytotoxic drugs which suppress cellular immune functions, are clearly associated with increased cancer risk. It is intriguing to think that prolonged exposure to ethanol-induced immunosuppression may be a cofactor in the promotion of cancer. The tumor promotion may take place via a variety of mechanisms as discussed in this paper, including reduced host defenses by direct effects of ethanol, its metabolites, and/or malnutrition. It may be beneficial to test methods for immunostimulation in prolonged alcohol abusers, where cessation of use is unsuccessful or residual immunosuppression remains, to reduce the risk of development or growth of initiated tumors.

Ethanol-mediated promotion of oral carcinogenesis in hamsters: association with lipid peroxidation.

Pouches of male Syrian Golden hamsters were painted with 1% 7,12-dimethylbenz[a]anthracene (DMBA) three times for one week. One week after DMBA treatment, hamsters were fed an ethanolic diet and continued on this diet until they were killed 22 and 35 weeks after the start of the experiment. Phospholipids, cholesterol, indexes of lipid peroxidation (malondialdehyde, diene and triene conjugates, lipid fluorescence), and the antioxidants glutathione and vitamin E were determined in the buccal mucosa, as was the incidence of tumors. At 22 weeks, the relative proportion of cholesterol to phospholipids in ethanol-consuming hamsters was significantly increased. At 35 weeks, most of the treatments showed a return of cholesterol vs. phospholipids toward that of untreated mucosa at 22 weeks. Ethanol consumption also increased the indexes of lipid peroxidation at 22 weeks; the largest increases occurred when ethanol use was combined with DMBA treatment. However, at 35 weeks such increases in lipid peroxidation had either returned to intermediate levels or were not different from the untreated controls at 22 weeks. Glutathione decreased in pouches of hamsters fed ethanol diets at 22 weeks, but at 35 weeks there was no appreciable difference. However, vitamin E increased significantly with ethanol consumption at 22 weeks, which increased further when combined with DMBA treatment, but at 35 weeks these values were intermediate. No tumors were seen at 22 weeks. At 35 weeks, DMBA-treated ethanol-fed hamsters had a significantly higher incidence of tumors, more multiple tumors per hamster with tumors, and more of the larger tumors than DMBA-treated control-fed hamsters. The results suggest that an increase in lipid peroxidation occurs with ethanol-related tumor promotion processes, but this lipid peroxidation declines when tumors appear to be preceded by increases in cholesterol relative to phospholipids and increases in vitamin E.

Alcohol stimulation of lipid peroxidation and esophageal tumor growth in mice immunocompromised by retrovirus infection

Tumor appearance can be accelerated in the immunodeficient and immunosuppressed animal. The role of lipid peroxidation and immune dysfunction induced by retrovirus and ethanol treatments on cancer promotion were investigated. Following the initiation of esophageal cancer by methylbenzylnitrosamine, ethanol consumption and retrovirus infection individually and concomitantly increased growth of esophageal tumors. Dietary supplementation with vitamin E reduced the size and frequency of the developed tumors. Tumor growth modifications in the vitamin E supplemented animals may be due to changes in T-cell numbers and functions stimulated by vitamin E. In addition, increased production of free radicals following ethanol treatment and retrovirus infection, and the suppression of these formations lipid peroxide by vitamin E is accompanied by lower incidence and size of tumors. Thus, the mechanisms of tumor enhancement observed in immunocompromised animals may include a combination of immunomodulation and modification of oxidant production by ethanol consumption and retrovirus infection.

Dietary polyunsaturated fatty acid promote peroxidation and its possible role in the promotion of cancer.

It is known that an interplay between dietary, hereditary and environmental factors initiate and/or promote cancer. Several factors associated with high risk of the development of diseases including cancer have been identified. Included in these is the amount and type of dietary fat. Circumstantial evidence provided by epidemiological studies is further supported by laboratory models that provide strong correlation between dietary fat and cancer. These studies have consistently shown that high dietary fat level of 20 percent (w/w) or 40 percent by calories promote spontaneous or induced mammary tumor growth in rats and mice (Tinsley et al., 1981, Carrol et al., 1970). Polyunsaturated fatty acid containing several double bonds are unstable molecules and are readily oxidized by non-specific and specific lipoxygenases and cyclo-oxygenase enzymes systems to yield free radicals and peroxides, which are toxic to cells. Although the peroxidation of lipids have been involved in certain forms of tissue pathology and tumor growth, the mechanism and role of these fatty acids in the development of tumors has not been completely defined. Therefore, the effect of dietary cod liver oil, a polyunsaturated fatty acid, in vivo -1-lipid peroxidation as measured by ethane exhalation was investigated.

Inhibition of ethanol induced ethane exhalation by carcinogenic pretreatment of rats 12 months earlier

The exhalation of ethane was used as a measure of in vivo lipid peroxidation in rats treated with the hepatocarcinogen diethylnitrosamine followed by 2-acetylaminofluorene (AAF), and carbon tetrachloride, and subsequently fed a liquid diet containing 7% ethanol for 12 months. The other groups consisted of animals treated with methylbenzylnitrosamine (MBN), an esophageal carcinogen, or non-carcinogen pretreated animals with or without 7% ethanol feeding. Ethane production was increased in rats consuming ethanol irrespective of their pretreatment with MBN. In sharp contrast, the ethanol-induced increase of ethane production was absent in rats given the hepatocarcinogenic regime. Our results strengthen recent observations indicating decreased susceptibility of tumor cells to lipid peroxidation. In addition, they confirm the debated concept that there is increased lipid peroxidation following ethanol consumption.

Inhibition of UV and psoralen-plus-light mutagenesis in phage T4 by gene 43 antimutator polymerase alleles.

Abstract— Mutagenesis by UV light or psoralen‐plus‐light was measured by increases in the reversion of nonsense mutants of phage T4. In the presence of either of two gene 43 antimutator polymerase alleles, tsCB120 or tsCB87, UV‐induced reversion was inhibited. Likewise psoralen‐plus‐light mutagenesis was inhibited when the tsCB120 allele was present. These results imply that the gene 43 DNA polymerase has a role in the formation of mutations from the DNA lesions induced by UV and psoralen‐plus‐light.

Effect of ethanol consumption and vitamin E supplementation on in vivo lipid peroxidation in rats

Abstract This study investigated the effects of short and long term vitamin E supplementation on ethanol induced lipid peroxidation in rats. Groups of rats were fed liquid diets in which ethanol provided 36% of the total calories (v/v) for 28 days or 18 months. The 28-day fed rats received supplemental alpha tocopherol 142 IU/kg of diet while those fed ethanol for 18 months were injected i.p. with 528 IU alpha tocopherol/kg body weight/day for 2 days prior to termination. At the end of the feeding period, ethane exhalation, conjugated dienes and lipid fluorescence were estimated as indices of free radical mediated products. Rats fed the ethanol diets for 28 days and 18 months exhaled more ethane than pair-fed controls. Increases in conjugated dienes and lipid fluorescence were observed in both the 28 day and 18 month groups of alcohol fed rats (p

Mutator effects of alleles of phage T4 genes 32, 41, 44, and 45 in the presence of an antimutator polymerase

Abstract When eight phage T4 rII base substitution mutations were each combined with an antimutator allele of gene 43 (DNA polymerase), reversion frequencies of the rII mutations were reduced from 3- to 90-fold. When these eight rII-gene 43 allele combinations were then combined with an allele of gene 32 (helix-destabilizing protein), the low reversion index was maintained in five cases. In the remaining three cases, strong mutator effects by the gene 32 allele were observed. One of these three rII alleles was then used as a tester in combination with an allele from each of genes 30, 37, 39, 41, 44, 45, 47, and 56. The corresponding triple mutants, consisting of the rII allele, the gene 43 antimutator allele, and an allele from each of the above genes was also constructed. The alleles of genes 41, 44, and 45 displayed strong mutator effects in the presence of the gene 43 antimutator polymerase and much weaker mutator effects in the presence of wild-type polymerase. The tested alleles of genes 30, 37, 39, 47, and 56 did not have such mutator effects. The genes whose alleles showed strong mutator effects (32, 41, 44, and 45) have been identified previously as being essential for DNA synthesis in vivo, and for a rapid rate of replication in vitro. It has recently been hypothesized that these gene products and the products of genes 61 and 62 may interact with the gene 43 DNA polymerase to form a multienzyme replicative complex which governs the accuracy of replication. The data presented here, together with previously reported results on mutator effects, support the hypothesis that all seven gene products of the replicative complex have a strong influence on the accuracy of replication.