A radioimmunoassay for human antibody specific for microbial antigens.

A simple and sensitive method for detecting and quantitating antibody specific for microbial antigens is described. Bacterial, fungal, parasitic or viral antigens attached to bromoacetyl cellulose or the intact cells themselves were added to a series of two-fold dilutions of human serum. After a short incubation period, which allowed human antibody to attach to the antigens, the complex was thoroughly washed and carbon-14 labeled anti-human light chain antibody was added to each dilution. The resulting complex was washed, collected on a filter pad, placed in a scintillation vial and radioassayed. The relationship between radioactivity bound and --log2 of the serum dilution was linear. The endpoint for each assay and a confidence interval was calculated by doing inverse prediction from simple linear regression. Results obtained using this assay indicated the presence of antibody in a pool of normal human sera specific for herpes virus and for both cell surface and intracellular antigens of Streptococcus mutans, Naegleria fowleri, and Cryptococcus neoformans. In general the dominant response was against the intracellular antigens rather than cell surface antigens.

Role of dimethylnitrosamine-demethylase in the metabolic activation of dimethylinitrosamine.

In vivo administration to rats of the mixed-function oxidase modifiers 3-methylcholanthrene (MC), pregnenolone-16 alpha-carbonitrile (PCN) or beta-naphthoflavnoe (beta-f) inhibits the hepatic microsome-catalyzed in vitro binding of dimethylnitrosamine (DMN) to DNA. This parallels their effect on DMN-demethylase I, regarded to be the sole activating step in DMN carcinogenesis and fails to account for the previously observed anomaly that MC and PCN inhibit, while beta-NF enhances, the hepatocarcinogenic activity of DMN. The in vitro binding of DMN is clearly dependent on microsomes and NADPH, and is strongly enhanced by soluble cytoplasmic proteins; the presence of the latter has no effect. however, on the relative response to pretreatment by the modifiers. In mice beta-NF enhances and PCN inhibits DMN-demethylase I; beta-NF has no effect on either the cytochrome P-450 level or on the LD50, while PCN strongly increases the cytochrome P-450 level but without influencing the LD50. Neither of the two modifiers has any effect in mice on the host-mediated mutagenicity of DMN in a dose-response study, except for the highest dose of DMN (200 mg/kg) where PCN pretreatment significantly enhanced mutagenicity. To account for the anomalous observations, other potential pathways of DMN metabolism have been explored. Whole rat liver nuclei or isolated nuclear membrane fractions contain no DMN-demethylase or diethylnitrosamine-deethylase activity. In a microsomal mixed-function amine-oxidase assay system neither purified enzyme preparations nor whole microsomes catalyze NADPH oxidation in the presence of DMN as substrate. In addition, the purified enzyme does not catalyze formaldehyde production in the DMN-demethylase assay system. Benzylamine, a typical inhibitor of mitochondrial monoamine oxidase (MAO), is a potent inhibitor of DMN-demethylase activity, but microsomes are devoid of MAO activity. Furthermore, purified MAO has no DMN-demethylase activity. The differential effect of modifiers on the carcinogenicity of DMN probably involves pathways other than DMN metabolism.

In vitro cell transformation screening of 4 toluene diamine isomers.

2,4-, 2,5-, 2,6- and 3,4-Toluene diamine (TDA) were tested for their ability to enhance the transformation of primary hamster embryo cells (HEC) by Simian adenovirus 7 (SA7) when administered either prior to or after virus inoculation and for their ability to transform secondary HEC. 2,4-TDA was inactive when given prior to SA7, but active if given after. 2,5-TDA was active in both protocols. 2,6-TDA was marginally active if administered before virus and was the most active of the isomers when administered after virus. 3,4-TDA was the most active compound when added prior to SA7, and was also active when given after virus. All the isomers were capable of producing good dose--responses and absolute increases in the number of virus-transformed foci per dish in one or both of the experimental regimens. Each isomer chemically transformed secondary HEC but good dose--responses were rare, and none of the chemicals were active in more than 50% of the 5 or 6 separate tests performed on each.

In vitro mutagenicity and cell transformation screening of phenylglycidyl ether.

Phenylglycidyl ether (1,2-epoxy-3-phenoxy propane) (PGE) was tested for genetic activity in bacterial and mammalian tests. It was active in the Salmonella/microsome mutagenicity test. Concentration-dependent mutagenicity was demonstrated in S. typhimurium strains TA1535 and TA100 with and without rat S9, but not in strains TA98, TA1537, or TA1538. These results suggest PGE, is a direct-acting mutagen causing base substitutions. Phenylglycidyl ether did not induce 6-thioguanine-resistant mutants of Chinese hamster ovary cells, with or without rat S9, and with or without serum in the medium. Dose-dependent enhancement of SA7 virus transformation of primary hamster embryo cells was observed at concentrations of 1.6 microgram/ml and higher. In addition, this compound was able to chemically transform secondary hamster embryo cells at concentrations of 6.2 micrograms/ml and higher. At a dose of 2500 mg/kg p.o., PGE was active in the host-mediated assay using C57B1/6 X C3H mice and S. typhimurium strain TA1535. This activity represented a positive response in 2 of 5 animals tested. Murine testicular DNA synthesis was not inhibited by oral administration of PGE at 500 mg/kg.

In vitro mutagenicity and cell-transformation screening of N-(2,3-epoxy-propyl)-phthalimide.

N-(2,3-Epoxy-propyl)-phthalimide (EPP) was tested for genetic activity in the Salmonella/microsome mutagenicity test. Concentration-dependent mutagenicity was demonstrated in S. typhimurium strains TA1535, TA1537 and TA100 with and without rat S9. It was inactive in strain TA1538, and active without rat S9 in TA98 at the high dose. EPP induced 6-thioguanine-resistant mutants of Chinese hamster ovary cells in the absence of an exogenous activating system. EPP produced dose-dependent enhancement of SA7 virus transformation of primary hamster-embryo cells, and transformed secondary hamster-embryo cells in a non-dose-related fashion. At a dose of 5 g/kg p.o. or i.m., EPP was inactive in the host-mediated assay using C57Bl/6XC3H mice and S. typhimurium strain TA1535. Murine testicular DNA synthesis was not inhibited by oral administration of EPP at 1000 mg/kg.

Current epidemiologic status on aging in U.S. blacks: update on hypertension and diabetes.

The total number of American blacks aged 65 years and over is estimated to be approximately 2.3 million, and the black elderly population will continue to increase faster than the white elderly population throughout the remainder of this century. During the period 1985 to 2025, the elderly population in the United States will increase to 105 percent.The prevalence of hypertension and diabetes for the elderly population (65 years and over) is much higher in blacks than in whites. During the period 1976 to 1980, 76.5 percent of black women aged 65 to 74 years had definite hypertension, compared with 53.4 percent of white women.Many factors are associated with the development of hypertension and diabetes in blacks. Specfic epidemiologic studies are necessary to identify black-white differences in risk factors, including biomedical risk, socioeconomic status, psychosocial risk, nutritional status, lifestyle, and genetic factors.

Comprehensive family practice clerkship in a minority institution.

A comprehensive family practice clerkship program at Howard University College of Medicine has been conducted since 1970. This institution is one of three predominantly black institutions offering a family practice program. The senior clerkship is mandatory and at least 20 to 25 percent of each class elect to participate in a four-to six- week family practice preceptorship. As a result of the clerkship's success, over 50 percent of the program's graduates actively practice in primary medical manpower shortage or medically underserved areas.

Pulmonary tuberculosis in the elderly. Report of a case discovered at death.

Tuberculosis in the elderly takes on new significance. The case of an 87-year-old female nursing home resident is presented. She was admitted to the hospital with atypical pulmonary manifestations and right pleural effusion. Tuberculin skin tests were negative. The patient deteriorated and died. Disease due to Mycobacteria tuberculosis was discovered by culture after death.The prevalence of tuberculosis in the aged is increasing as the population ages. In the long-term-care setting, residents infected early in life outlive their tubercle bacilli. They are at risk of being infected again.Continuous clinical awareness in the geriatric segment of the population is essential if tuberculosis control is to be achieved. Tuberculin skin testing is important, with chemoprophylaxis for converters, and treatment for active disease.

Multifocal defects and splenomegaly in sarcoidosis: a new scintigraphic pattern.

Sarcoidosis involves the spleen in a significant percentage of patients afflicted with this disease. The most commonly applied modality for studying such patients is the (99m)Tc-sulfur colloid scan. Different patterns have been recognized: "normal" spleen and nonspecific splenic enlargement, with or without focal areas of photon deficiency, which was thought to represent an infarction in a previous report. We have encountered two patients showing splenomegaly and multifocal photon deficiencies secondary to sarcoid granulomata. These cases are presented to inform clinicians of a new pattern. Our patients were managed with systemic corticosteroids and palliation of pain. If symptoms persist or worsen, splenectomy may be necessary to avoid spontaneous rupture. An abbreviated differential diagnosis of the enlarged spleen with multiple focal defects is discussed.

In vitro mutagenicity and cell transformation screening of caprolactam.

Caprolactam was tested for genetic activity in bacterial and mammalian screens. It was inactive in the following tests: a) Salmonella/microsome mutagenicity; b) Chinese hamster ovary cell mutagenicity (induction of 6-thioguanine mutants); c) Enhancement of SA7 virus transformation of primary hamster embryo cells, when administered before or after virus, and; d) Chemical transformation of secondary hamster embryo cells.