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Biomedical subjects

A B Weitberg

Publications and source records attributed to A B Weitberg.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effects of hydrogen peroxide on oral carcinogenesis in hamsters.

The effects of twice weekly topical applications of hydrogen peroxide on the buccal epithelium of Syrian hamsters were studied. Animals were treated either with hydrogen peroxide alone, with hydrogen peroxide and the carcinogen 9, 10-dimethyl-1,2-benzanthracene (DMBA), or with DMBA alone. In animals treated with 30% H2O2 alone, histopathologic examination after 22 weeks revealed hyperkeratosis and hyperplasia in all animals with hyperchromatic cells and mild dysplasia in four of nine: no tumors were seen. In animals treated with DMBA alone, three of seven (43%) developed epidermoid carcinoma, while six of 11 (55%) of animals treated with DMBA plus 3% hydrogen peroxide and five of five (100%) of animals treated with DMBA plus 30% hydrogen peroxide (P = 0.054) developed carcinoma. Thus, hydrogen peroxide can, by itself, induce pathologic changes frequently associated with preneoplastic lesions; it may also augment carcinogenesis associated with DMBA.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1985

Phagocytes as carcinogens: malignant transformation produced by human neutrophils.

In a study of the relation between chronic inflammation and carcinogenesis, C3H mouse fibroblasts of the 10T 1/2 clone 8 line (10T 1/2 cells) were exposed to human neutrophils stimulated to synthesize reactive oxygen intermediates or to a cell-free enzymatic system generating superoxide (xanthine oxidase plus hypoxanthine). After exposure, the 10T 1/2 cells were either placed in tissue culture or immediately injected into athymic nude mice. Both malignant and benign tumors developed in the mice injected with treated cells, but not in those injected with control cells; in one instance cells grown from one of the benign tumors subsequently developed a malignant phenotype. Malignant transformation was also observed in treated cells in the experiments in vitro.

Animals↗
PubMed1985

Asbestos-catalysed lipid peroxidation and its inhibition by desferroxamine.

In an effort to understand the properties of asbestos fibres that might contribute to their being toxic, we incubated three different varieties of asbestos with phospholipid emulsions and looked for evidence of lipid peroxidation. Although all three types of asbestos were able to catalyse lipid peroxidation in the native state, this catalytic activity was inhibited by pre-washing of the asbestos with the iron chelator desferroxamine. This suggests that: lipid peroxidation may be one of the mechanisms by which asbestos produces tissue injury, and treatment with iron chelators might diminish the potential to produce this injury.

Adenosine Diphosphate↗
PubMed1985

The effect of vitamin C on oxygen radical-induced sister-chromatid exchanges.

We studied the effects of vitamin C (sodium ascorbate) on the genotoxicity of oxygen radicals to tissue culture cells. Chinese hamster ovary cells (CHO cells), when exposed to an enzymatic oxygen radical generating system (xanthine oxidase plus hypoxanthine), develop increased numbers of sister-chromatid exchanges (SCEs). Inclusion of ascorbate in these incubations resulted in significant, but variable effects. In some cases, ascorbate (less than 0.1 mM) was protective and fewer SCEs were produced. In others, significant augmentation of oxygen radical-induced SCEs occurred. These experiments illustrate the complexity of the interactions of ascorbate in biologic systems and the difficulty of predicting a desirable or harmful effect.

Animals↗
PubMed1985

Effects of antioxidants on oxidant-induced sister chromatid exchange formation.

Stimulated human phagocytes produce sister chromatid exchanges in cultured mammalian cells by a mechanism involving oxygen metabolites. Experiments were designed to determine whether antioxidants inhibit this process. Superoxide dismutase, catalase, and hydroxyl radical scavengers (benzoate, mannitol) protected target Chinese hamster ovary cells from phagocyte-induced sister chromatid exchanges, implicating the involvement of hydroxyl radicals in this chromosomal damage. N-acetylcysteine and beta-carotene were also protective. alpha-Tocopherol (greater than 5 microM) protected target cells exposed to phagocytes but not to enzymatically generated oxidants when the vitamin was added just before the source of oxygen radicals, suggesting, as reported by others, that the principal action of tocopherol in this setting was to inhibit the release of oxidants from phagocytes. On the other hand, cultivation of target cells with supplemental tocopherol protected them from the toxic effects of the enzymatic oxidant-producing system, indicating a role for membrane-associated free radicals in the mechanism of sister chromatid exchange induction. Low concentrations of sodium selenite (0.1-1.0 microM) protected the target cells. However, higher concentrations (10 microM) of selenite had no effect on oxidant-induced sister chromatid exchange formation, and 0.1 mM selenite increased the number of exchanges. Sodium selenite concentrations of 0.1 mM also decreased the intracellular glutathione concentration of target cells during an oxidant stress, and reducing target cell glutathione concentrations with buthionine sulfoximine increased their sensitivity to oxygen-related chromosomal damage. Therefore, the potentiation of oxygen radical-induced chromosomal damage observed with high concentrations of selenite may result from a decrease in the thiol antioxidant defense systems within the cell. The findings suggest that the hydroxyl radical has an important role in the production of phagocyte-induced cytogenetic injury, membrane-derived intermediates may be involved, depletion of intracellular glutathione renders cells more susceptible to this injury, and supplementation of target cells with antioxidants can protect them from oxygen radical-generated chromosomal injury.

Acetylcysteine↗
PubMed1985

Immunogenicity of hepatitis B vaccine in oncology patients receiving chemotherapy.

We evaluated the immunogenicity and safety of three 40 micrograms doses of hepatitis B vaccine in oncology patients receiving chemotherapy. Of 76 patients screened for entry into the study, 13 (17%) already had been exposed to hepatitis B and were ineligible; 26 chose to join the study. The cumulative life-table response rate during the 12-month observation period was 70.8%; adequate immune response was linked to survival, 73% in survivors completing the study and 9% in nonsurvivors. Adverse effects were minor. We conclude that hepatitis B vaccine is safe and usually effective in inducing immunity in oncology patients younger than 60 years of age who are receiving chemotherapy.

Adult↗
PubMed1984

Chronic treatment with hydrogen peroxide. Is it safe?

The regular application of hydrogen peroxide to gingival tissues is becoming widely used as part of dental hygiene. Since hydrogen peroxide can be toxic under certain experimental conditions, proof of both safety and efficacy of its chronic administration should be available before prescription to the general public.

Animals↗
PubMed1982

Effect of low-dose heparin on the platelet count.

Thrombocytopenia has been associated with the use of intravenous heparin, but the effect of low-dose, subcutaneously administered heparin on the platelet count is not known. We monitored the platelet counts in 50 patients admitted to a coronary care unit and given low doses of heparin for at least three days. No patient had thrombocytopenia during an observation period of 15 days. We conclude that routine measurement of the platelet count is unnecessary when low-dose heparin is used in this patient population.

Adult↗
PubMed1981

Streptococcus bovis meningitis and carcinoma of the colon.

A 90-year-old woman who presented with Streptococcus bovis meningitis was found at autopsy to have a colonic carcinoma. Although the association between colonic carcinoma and S. bovis endocarditis or bacteremia is well-documented in the literature, S. bovis meningitis is uncommon. A thorough investigation of the gastrointestinal tract should be undertaken in patients with S. bovis infections even in the absence of gastrointestinal signs or symptoms.

Aged↗
PubMed1980

Minidose heparin therapy. Treatment of chronic intravascular coagulation syndrome.

An elderly patient had multiple life-threatening episodes of disseminated intravascular coagulation (DIC). There was no apparent cause other than an abdominal aortic aneurysm. Her condition was maintained with minidoses of subcutaneously administered heparin sodium in the acute stages and as an outpatient for seven months, which proved to be an effective therapy. We suggest that minidoses of heparin can be used in the treatment of DIC and that this is a safe, easily administered mode of therapy, especially in the outpatient setting.

Aged↗