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Biomedical subjects

J C Merrill

Publications and source records attributed to J C Merrill.

35 records · Page 2Linked to original sources
PubMed1985

The in vitro metabolism of benzo[a]pyrene by polychlorinated and polybrominated biphenyl induced rat hepatic microsomal monooxygenases.

The metabolism of benzo[a]pyrene by halogenated biphenyl-induced rat hepatic microsomal monooxygenases was determined using a high pressure liquid chromatographic assay system. Incubation of benzo[a]pyrene with microsomes from rats pretreated with phenobarbitone or phenobarbitone-type inducers (2,2',4,4',5,5'-hexachlorobiphenyl, 2,2',4,4',6,6'-hexachlorobiphenyl, 2,2',5,5'-tetrachlorobiphenyl, 2,2',4,4',5,5'-hexabromobiphenyl, and 2,2',5,5'-tetrabromobiphenyl) resulted in increased overall metabolism of the hydrocarbon (less than fourfold) into phenolic, quinone, and diol metabolites, with the most striking increase observed in the formation of 4,5-dihydro-4,5-dihydroxybenzo[a]pyrene. In contrast, the metabolism of benzo[a]pyrene by microsomes from rats induced with 3-methylcholanthrene or 3,3',4,4'-tetrachlorobiphenyl resulted in a greater than 10-fold increase in overall benzo[a]pyrene metabolism, with the largest increases observed in the formation of the trans-7,8- and -9,10-dihydrodiol metabolites of benzo[a]pyrene. However, in comparison to control and phenobarbitone-induced microsomes, the oxidative conversion of benzo[a]pyrene by microsomes induced with 3-methylcholanthrene and 3,3',4,4'-tetrachlorobiphenyl into the 6,12-quinone was substantially inhibited. Previous reports have shown that the commercial halogenated biphenyl mixtures, fireMaster BP-6, and Aroclor 1254 are mixed-type inducers and that microsomes from rats pretreated with these mixtures markedly enhance the overall metabolism of benzo[a]pyrene. Not surprisingly, the metabolism of benzo[a]pyrene by microsomes from rats pretreated with the mixed-type inducers, 2,3,3',4,4'-penta-,2,3,3',4,4',5-hexa-, and 2',3,3',4,4',5-hexa- chlorobiphenyl was also increased and the metabolic profile was similar to that observed with fireMaster BP-6 and Aroclor 1254 induced microsomes.

Animals↗
PubMed1984

DRG-based case mix and public hospitals.

The 12 acute care public hospitals in New York City (HHC hospitals) are compared with a matched group of nonpublic hospitals (non-HHC hospitals). The following questions are considered: using DRGs to define case mix, how does the case mix of HHC and non-HHC hospitals differ; to what extent do differences in case mix account for differences in average length of stay (ALOS); can factors other than case mix be identified that may explain differences in ALOS? Although about one half of the 20 most prevalent DRGs are similar in both types of institutions, there are clear case mix differences. The higher percentage of abortion, psychiatric, and chemical dependence discharges and the lower prevalence of surgery in HHC hospitals contribute to this difference. The case load is more concentrated in fewer DRGs in HHC hospitals. HHC hospitals treat more patients in DRGs with a shorter ALOS, but, on the average, patients in the same DRG stay more than 1 day longer in HHC facilities. To some extent, this longer LOS can be explained by differences in payor type, primary diagnosis within a DRG, and, most important, in the percentage of outlier patients.

Costs and Cost Analysis↗
PubMed1984

Health care institutions: survival in a changing environment.

The health care system in the United States has been altered by recent economic and political events, including a major recession and a retrenchment in federal nonentitlement spending programs. The economic recovery and the continuing high federal deficits prompt new questions about both the future expansion and the distribution of health spending. Long-term economic forecasts and public opinion polls suggest that health will consume a growing share of the national resources. Nevertheless, the level of health spending will not grow as rapidly as in the past, and the distribution of that spending may also change. Because of these changes, the growth in health spending will not guarantee the survival of existing institutions. New competitive forces and revised reimbursement mechanisms will lead to a redistribution of the health dollar, and this redistribution will create both risk and opportunity for America's important health care institutions and their health professionals.

Academic Medical Centers↗
PubMed1983

Effects of species, MFO inducers and conjugation agents on the in vitro covalent binding of 14C-3-methylindole metabolite in liver and lung tissues.

The degree of tissue covalent binding of 14C-3-methylindole metabolite in goat and rat pretreated with phenobarbital or 3-methylcholanthrene was compared. The effect of conjugating agents, i.e. glutathione (GSH), cysteine and sulfate, in reducing the degree of tissue covalent binding was measured. The degree of tissue covalent binding was significantly higher in the lung than the liver of goats. In rats, covalent binding was higher in the liver than the lung. Glutathione and cysteine were effective in decreasing the degree of in vitro covalent binding in both liver and lung tissues of goat and rat.

Animals↗
PubMed1983

The effect of dietary and sulfur compounds in alleviating 3-methylindole-induced pulmonary toxicity in goats.

The present experiment was designed to determine the effect of tissue concentrations of glutathione (GSH) and GSH-S-transferase activity on 3-methylindole (3MI)-induced pulmonary toxicity in vivo. Forty goats were given high protein, normal protein, high cysteine, high sulfate or diethyl maleate (DEM) to vary tissue concentrations of GSH before i.v. infusion of 3MI. The severity of lung lesion was scored. Tissue GSH concentration, GSH-S-transferase activity and cytochrome P-450 content were measured. Compared to goats fed normal protein diet, high cysteine or high sulfate increased the tissue GSH levels and reduced the severity of the lung lesion induced by 3MI. Pretreatment with DEM, by which the tissue GSH was depleted, increased the severity of 3MI-induced lung lesion. Tissue GSH-S-transferase activity was not changed. These results indicate that the tissue concentration of conjugating agents play an important role in 3MI-induced lung disease.

Animals↗
PubMed1982

The effect of dietary protein quantity on the activity of UDP-glucuronyltransferase and its physiological significance in drug metabolism.

Low dietary protein has been shown to induce the activity of rat hepatic UDP-glucuronyltransferase (UDPGTase) as measured in vitro. The assay of UDPGTase in vitro is hampered by the need to solubilize the microsomal membrane, without destroying the physiological significance of the measurements. The present work was to determine the effect of dietary protein on the activity of UDPGTase and on the activity of UDP-glucose dehydrogenase. Chloral hydrate induced sleeping time was used as a bioassay for UDPGTase, confirming the physiological significance of the in vitro analysis. Sixty male rats were maintained on three different protein levels (7.5, 15, and 45%) for 16 days. Fifteen rats from each group were sacrificed and hepatic UDPGTase, cytochrome P-450, UDP-glucose dehydrogenase, and alcohol dehydrogenase were assayed. Five rats from each group were dosed with 7.5% chloral hydrate (4.8 mL/kg body weight) to measure sleeping time. Rats on 7.5% dietary protein had significantly higher UDPGTase activity than rats fed either 15 or 45% protein diets. These differences in enzyme activity in vitro correlated with the differences in chloral hydrate sleeping time. Dietary protein was not found to affect the activity of UDP-glucose dehydrogenase as measured in vitro.

Animals↗
PubMed1975

Localization of radioactive lead in ocular and skin melanoma.

The ability of radioactive lead to localize melanomas was studied. The Greene melanoma in the Syrian Golden hamster served as a model for both skin and ocular melanoma. The affinity of heavy metals for neoplasms has been studied but previous reports have been inconsistent as to tumor specificity. For this investigation the radioactive lead (203-Pb,) was studied as the chemical complex 203-Pb-Tris. Significant tumor:nontumor ratios were found in ocular melanoma and the concentration in the lens was minimal. The ratio of per cent uptake per gram of tumor: per cent uptake per gram in control tissue with skin melanoma was 9.4 at 24 hours and for the eye melanoma the ratio was 26.3 at 24 hours. The affinity of 203-Pb-Tris for melanomas appears to be as promising as other compounds presently being evaluated for ocular scintigraphy, namely, labeled quinoline analogs. Therefore, further preclinical evaluation is warranted.

Animals↗
PubMedDate not supplied

Radiation therapy technologist survey: state of Michigan.

A survey of institutions in Michigan utilizing megavoltage equipment demonstrated a shortage of certified radiation therapy technologists. The low number of such personnel who can be trained in the available approved programs in the state is barely sufficient to maintain the present level. Projections show a continued shortage and a need for more approved radiation therapy technology training programs.

Michigan↗