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Biomedical subjects

D McBride

Publications and source records attributed to D McBride.

At least 55 records · Page 3Linked to original sources
PubMed1993

Black America: from community health care to crisis medicine.

This study traces the major policy shifts in medical care that have affected disadvantaged African-Americans and the response of this community's medical leadership to these changes. Since World War II policy has passed through three major phases. The first--engagement--ran from the mid-1960s through the mid-1970s. During this phase a community health policy orientation prevailed as national government targeted resources to health care programs for needy blacks and other poor Americans. From the late 1970s to the mid-1980s the period of submersion occurred: black community health professionals and political leaders experienced a new-found inclusion in health policy debate, but, at the same time, broader policy-making circles in government and health care reduced medical resources for the inner-city poor. Finally, in the third phase--crisis recognition--a network developed of community health advocates who seek to reorient the health system so that it addresses needs within urban American's "New Ghettos."

Black or African American↗
PubMed1993

Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on the proliferation of bovine granulosa cells in vitro.

Treatment of heifers with recombinant bovine somatotrophin (BST) significantly increases the population of small ovarian follicles and peripheral concentrations of somatotrophin, insulin-like growth factor-I (IGF-I) and insulin. To investigate the possible mechanism(s) involved in the action of BST on ovarian follicles, the effects of BST, IGF-I and insulin, given alone or in combination with either FSH or LH, on the proliferation of bovine granulosa cells in vitro were examined using a serum-free culture system. Bovine granulosa cells were obtained from antral follicles classified into three size categories according to diameter: small < 5 mm; medium-sized 5-10 mm and large > 10 mm. The proliferation of granulosa cells was assessed by the incorporation of [3H]thymidine into the cultured cells. Both FSH and LH (1-1000 ng/ml) inhibited the proliferation of bovine granulosa cells obtained from all three size classes of follicles in a dose-dependent manner. BST, at doses ranging from 1 to 1000 ng/ml, had no effect on the proliferation of granulosa cells from small and medium-sized follicles, but inhibited the division of granulosa cells from large follicles in a dose-dependent manner. Treatment with either IGF-I (10-3000 ng/ml) or insulin (0.5-1000 ng/ml) stimulated, in a dose-dependent manner, the proliferation of granulosa cells obtained from all three size categories of follicles. No synergistic interaction between BST (30 ng/ml) and either FSH (50 ng/ml) or LH (5 ng/ml) was observed in granulosa cells from all three size classes of follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Mechanism controlling ovulation rate in ewes in relation to seasonal anoestrus.

Three experiments were carried out during seasonal anoestrus in Finnish Landrace and Scottish Blackface ewes, to establish whether the differences between the breeds in ovulation rate are functional during the non-breeding season and are therefore independent of the mechanism controlling ovulation. In Expt 1, follicles greater than or equal to 2 mm in diameter were dissected from the ovaries of both breeds and incubated individually for 2 h to assess their ability to secrete oestradiol and testosterone. In both breeds, follicles producing greater than or equal to 500 pg oestrogen/ml/h (oestrogen-active) were readily identifiable from a population producing less (oestrogen-inactive). The number of oestrogen-active follicles in each breed was similar to the number of ovulations near the end of the breeding season. Oestrogen-active follicles also had more luteinizing hormone (LH) receptors and larger diameters than oestrogen-inactive follicles. There were, however, no significant differences between the two follicle types in follicular fluid or in-vitro testosterone concentrations. In Expt 2, seasonally anoestrous Scottish Blackface ewes were unilaterally ovariectomized; the second ovary was removed 7 days later. Follicles from both ovaries were processed as described for Expt 1; oestrogen-active follicles were categorized according to their ability to produce greater than 500 pg/ml/h. There were twice as many oestrogen-active follicles in the second ovary as in the first ovary; the number of oestrogen-active follicles in the second ovary was also similar to the total number of oestrogen-active follicles in both ovaries of the Scottish Blackface ewes in Expt 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Anestrus↗
PubMed1992

3 beta-hydroxysteroid dehydrogenase inhibitor reduces ovarian steroid production but increases ovulation rate in the ewe: interactions with gonadotrophins and inhibin.

Two experiments were carried out during the breeding season in ewes, first to investigate the effects of oral administration of a 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) inhibitor (epostane) on the number of corpora lutea, and secondly to investigate the mechanism through which epostane acts. In the first experiment Dorset Horn ewes were treated orally with 25, 50, 100 or 200 mg epostane twice daily between days 10 and 15 of the oestrous cycle. All doses of epostane resulted in an increase in the number of corpora lutea per ewe, although the response was curvilinear, with the 25 mg dose showing the largest response and the 200 mg group the smallest response. Although there was no difference between groups in the number of ewes showing oestrus, the higher doses of epostane had a detrimental effect on fertility. In the second experiment Welsh Mountain ewes were treated twice daily with 25 mg epostane from day 10 of the oestrous cycle and the ovaries were removed for analysis during either the luteal or the follicular phases. Treatment significantly increased the number of follicles greater than 6 mm in diameter, but significantly reduced in-vitro follicular oestradiol and testosterone production. Despite a marked increase in peripheral inhibin concentrations there was no effect on in-vitro inhibin production. Epostane treatment also caused a significant reduction in peripheral FSH concentrations and an increase in mean LH concentration. The latter was due to an increase in LH pulse frequency during the luteal phase and LH pulse amplitude during the follicular phase. These results confirm that treatment of ewes with epostane orally has a significant effect on follicular steroidogenesis and causes a significant increase in the number of corpora lutea per ewe. This effect on ovulation rate is not via an increase in peripheral FSH concentration, but may be caused by a reduction in follicular steroid activity either directly on the ovary or via an alteration in the pattern of LH secretion.

3-Hydroxysteroid Dehydrogenases↗
PubMed1991

Responses of the L5178Y mouse lymphoma forward mutation assay: V. Gases and vapors.

A new protocol for testing vapors and gases in the L5178Y mouse lymphoma assay is presented. Four chemicals, propylene, 1,2-propylene oxide, 1,3-butadiene, and vinylidene chloride, were tested for their mutagenic potential. Cultures were exposed to the chemicals, which were delivered as vapors or gases, for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 microgram/ml. Each chemical was tested at least twice. Significant responses were obtained with 1,2-propylene oxide and vinylidene chloride, but neither cytotoxicity nor mutagenicity was induced by 1,3-butadiene; propylene could not be classified as either mutagenic or non-mutagenic in the assay. Rat liver S9 mix was not a requirement for the mutagenic activity of 1,2-propylene oxide, whereas the liver preparation markedly enhanced both the cytotoxicity and mutagenicity of vinylidene chloride.

Air Pollutants↗
PubMed1991

Responses of the L5178Y mouse Lymphoma cell forward mutation assay. V: 27 coded chemicals.

Twenty-seven chemicals were tested for their mutagenic potential in the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay using procedures based upon those described by McGregor et al. (McGregor DB, Martin R, Cattanach P, Edwards I, McBride D, Caspary WJ (1987): Environ Mol Mutagen 9:143-160). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The chemicals were tested at least twice. Statistically significant responses were obtained with acid orange 10, aniline, benzaldehyde, o-chloroaniline, chlorodibromomethane, cytembena, 1,2-dibromo-4-(1,2-dibromomethyl) cyclohexane, dieldrin, lithocholic acid, oxytetracycline, phenazopyridine HCl, 1-phenyl-3-methyl-5-pyrazolone, sodium diethyldithiocarbamate, solvent yellow 14, tetraethylthiuram disulfide (disulfiram), 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate. Apart from phenazopyridine HCl, acid orange 10, and solvent yellow 14, rat liver S9 mix was not a requirement for the mutagenic activity of these compounds. Chemical not identified as mutagens were N-4-acetylaminofluorene, chlorpheniramine maleate, chloropropamide, 1,4-dioxane, endrin, ethylene glycol, iron dextran, methapyrilene, sodium(2-ethylhexyl)alcohol

Animals↗
PubMed1991

Ciprofloxacin versus gentamicin in prophylaxis against bacteremia in transrectal prostate needle biopsy.

Consecutive patients with abnormal rectal examinations underwent transrectal needle prostate biopsy at VA Medical Center, New Orleans. Each patient was randomized to receive either gentamicin 1.5 mg/kg intravenously (IV) or 500 mg ciprofloxacin (Cipro-Miles) p.o., before and after the biopsy. Serum and prostate tissue levels of ciprofloxacin and gentamicin were measured by high-pressure liquid chromatography and by competitive binding immunoassay, respectively. Blood cultures were obtained, and the patients were observed for twenty-four hours after biopsy. After discharge the patients were followed up by telephone. The incidence of bacteremia and postbiopsy symptoms were less with ciprofloxacin. Prostate tissue levels of this drug were higher than gentamicin, while serum levels were roughly equivalent. Ciprofloxacin is less nephrotoxic, can be given orally, and has a better antimicrobial spectrum. We, therefore, recommend it as prophylaxis against bacteremia in transrectal prostate needle biopsy. Furthermore, it appears that prostatic drug levels are more important than serum levels in preventing bacteremia.

Aged↗
PubMed1991

An analysis of cerebral blood flow in acute closed-head injury using technetium-99m-HMPAO SPECT and computed tomography.

Technetium-99m-hexamethylpropyleneamine (HMPAO) SPECT and x-ray CT were compared in 15 patients with acute closed-head injury. There were 44 focal lesions in all. Fifteen (34%) lesions were seen on both x-ray and SPECT. Seventeen (39%) lesions were seen only on SPECT. Twelve (27%) of the lesions were seen on x-ray tomography only. Of the lesions seen on x-ray tomography but not on SPECT, two were subarachnoid hemorrhage, two were thin subdural hematomas, and eight were contusions. This study shows that SPECT can detect focal disturbances of cerebral blood flow that are not seen on x-ray tomography. It also suggests that there are two types of contusions: those with a decreased cerebral blood flow (i.e., detectable on SPECT) and those with a cerebral blood flow equal to that of the surrounding brain.

Acute Disease↗
PubMed1990

L5178Y mouse lymphoma cell mutation assay results with 41 compounds.

Forty-one chemicals were tested for their abilities to induce trifluorothymidine resistance in L5178Y mouse lymphoma (MOLY) cells. These chemicals were included in the National Toxicology Program's evaluation of four in vitro short-term toxicity assays for predicting carcinogenicity in the rodent bioassay. Of the 41 chemicals examined for this report, 8 were equivocal in the rodent bioassay, and 7 were questionable in- the MOLY assay. If these chemicals are eliminated from an analysis of concordance, the remaining 26 chemicals lead to a concordance of 69% with a sensitivity of 71%. The specificity could not be determined because only two non-carcinogens were detected.

Animals↗
PubMed1990

Studies on the activities of benzo[a]pyrene, benzidine and ethyl methanesulphonate in the L5178Y TK +/- mouse lymphoma mutagenicity assay using standardized and non-standardized protocols.

As part of the third UKEMS collaborative trial, ethylmethane sulphonate (EMS), benzo[a]pyrene (B[a]P) and benzidine (BZD) were assayed for mutagenicity using the L5178Y mouse lymphoma TK +/- forward mutation system. Exogenous metabolic activation was achieved with two different sources of rat liver S9 which were used under optimized conditions for B[a]P and BZD, the latter being tested also without S9. EMS was assayed in the absence of S9 only. Mutants were selected for trifluorothymidine (TFT) resistance after 48 and 72 h expression time. Mutant frequency (MF) data were subjected to ANOVA analysis and t-tests for differences between replicate cultures, linear trend and differences from solvent controls. Large TFT resistant colonies are believed to be due to induction of small amounts of genetic damage (point mutations, small deletions) at the tk locus, whilst small colonies are thought to be a result of larger effects. The relative proportions of the two colony types were determined in some experiments. All three compounds induced dose-related increases in MF under all conditions. B[a]P induced equal proportions of large and small colonies at all doses. EMS induced predominantly large colonies at all doses. The effect of BZD on colony size was variable. The source of S9 did not exert any consistent effect on toxicity, mutagenicity or mutant colony size. Maximum MF values occurred at 72 h for B[a]P and BZD but the results with EMS were variable. No consistent differences were apparent between estimates of toxicities made either by cloning immediately after treatment (day 0 cloning) or by estimating the relative total growth (RTG) at expression time.

Animals↗
PubMed1989

Drug defect reporting.

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Drug-Related Side Effects and Adverse Reactions↗
PubMed1988

Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay. II: 18 coded chemicals.

Eighteen chemicals were tested for their mutagenic potential in the L5178Y tk+/- mouse lymphoma cell forward mutation assay by the use of procedures based upon those described by Clive and Spector [Mutat Res 44:269-278, 1975] and Clive et al [Mutat Res 59:61-108, 1979]. Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The chemicals were tested at least twice. Significant responses were obtained with benzofuran, benzyl chloride, bromodichloromethane, butylated hydroxytoluene, chlorendic acid, o-chlorobenzalmalonitrile, 1,2,3,4-diepoxybutane, dimethyl formamide, dimethyl hydrogen phosphite, furfural, glutaraldehyde, hydroquinone, 8-hydroxyquinoline, and resorcinol. Apart from bromodichloromethane, butylated hydroxytoluene and dimethyl hydrogen phosphite, rat liver S9 mix was not a requirement for the activity of any of these compounds. Chemicals not identified as mutagens were water, tert-butyl alcohol, pyridine, and witch hazel.

Animals↗
PubMed1988

Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay: III. 72 coded chemicals.

Seventy-two chemicals were tested for their mutagenic potential in the L5178Y tk+/- mouse lymphoma cell forward mutation assay, using procedures based upon those described by Clive and Spector (Mutat Res 44:269-278, 1975) and Clive et al. (Mutat Res 59:61-108, 1979). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The chemicals were tested at least twice. Significant responses were obtained with allyl isothiocyanate, p-benzoquinone dioxime, benzyl acetate, 2-biphenylamine HCl, bis(2-chloro-1-methylethyl)ether, cadmium chloride, chlordane, chlorobenzene, chlorobenzilate, 2-chloroethanol, chlorothalonil, cytarabine.HCl, p,p'-DDE, diazinon, 2,6-dichloro-p-phenylenediamine, N,N-diethylthiourea, diglycidylresorcinol ether, 2,4-dimethoxy aniline.HCl, disperse yellow 3, endosulfan, 1,2-epoxyhexadecane, ethyl acrylate, ethyl benzene, ethylene thiourea, F D and C yellow Number 6, furan, heptachlor, isophorone, mercuric chloride, 4,4'-methylenedianiline.2 HCl, methyl viologen, nickel sulfate.6H2O, 4,4'-oxydianiline, pentachloroethane, piperonyl butoxide, propyl gallate, quinoline, rotenone, 2,4,5,6-tetrachloro-4-nitro-anisole, 1,1,1,2-tetrachloroethane, trichlorfon, 2,4,6-trichlorophenol, 2,4,5-trimethoxybenzaldehyde, 1,1,3-trimethyl-2-thiourea, 1-vinyl-3-cyclopetene dioxide, vinyl toluene, and ziram. Apart from 2-biphenylamine.HCl, 2-chloroethanol, disperse yellow 3, ethylene thiourea, FD and C yellow number 6, phenol, and 1,1,2-tetrachloroethane, rat liver S9 mix was not a requirement for these compounds. Chemicals not identified as mutagens were acid red, 11-aminoudecanoic acid, boric acid, 5-chloro-o-toluidine, coumaphos, cyclohexanone, decabromodiphenyl oxide, di(2-ethylhexyl)adipate, ferric chloride, fluometuron, melamine, monuron, phenesterin, phthalimide, reserpine, sodium dodecyl sulfate, 4,4-sulfonyldianiline, tetrachloroethylene, and zearalenone. The assay was incapable of providing a clear indication of whether some chemicals were mutagens; these were benzyl alcohol, 1,4-dichlorobenzene, phenol, succinic acid-2,2-dimethyl hydrazide, and toluene.

Animals↗
PubMed1987

Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay to coded chemicals. I: Results for nine compounds.

Nine substances were tested for their mutagenic potential in the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay, by means of procedures based upon those described by Clive and Spector (Mutat Res 44:269-278, 1975) and Clive et al (Mutat Res 59:61-108, 1979). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The coded chemicals were tested at least twice. Significant responses were obtained with calcium chromate, 3-(chloromethyl)pyridine, 1,2-epoxybutane, monochloroacetic acid, dicyclohexylthiourea, 2,4-diaminophenol hydrochloride, and pentachloroanisole. Apart from pentachloroanisole, rat liver S9 mix was not a requirement for the clearly mutagenic activity of any of these compounds. Compounds not identified as mutagens were 3-amino-1,2,4-triazole and sucrose.

Acetates↗