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Biomedical subjects

J Merrill

Publications and source records attributed to J Merrill.

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

Ethnic differences in self-poisoning: a comparison of Asian and white groups.

The characteristics of Asian patients admitted to a Birmingham hospital following deliberate self-poisoning were compared with those of British-born white self-poisoners. Asian patients were more likely to be young, female, and married. They were less likely to have previously self-poisoned, received previous psychiatric treatment, be diagnosed psychiatrically ill, or suffer from a personality disorder. Culture conflict was common among the Asian patients and was present in the majority of unmarried Asian females. The rate of self-poisoning for Asian females was higher than for white females, but for Asian males was lower than for white males.

Adolescent↗
PubMed1986

Competition versus regulation: some empirical evidence.

In response to dramatic rises in health care costs, policymakers have been debating the relative merits of regulatory and competitive strategies as a means of containing costs. One major activity espoused by proponents of competition is the growth of health maintenance organizations (HMOs) which, in their opinion, will result in the market better determining efficient levels of utilization and costs. Extending this argument, the larger the percent of the population in a market area who enroll in HMOs, the greater the market-forcing effect of HMOs in reducing overall hospital expenditures; that is, if HMOs are providing lower-cost care, then the fee-for-service system will be forced to reduce costs in order to be competitive. The authors studied the 25 largest SMSAs from 1971-1981, and controlling for environmental conditions in each market, they examined the impact of both HMO growth and regulatory activity on costs and utilization. They conclude that neither competition nor regulation had a significant impact in reducing overall hospital costs. While there may have been some impact in specific communities, no generalizable effect could be observed. However, the authors did find that increases in costs and utilization were essentially driven by supply factors such as the number of hospital beds or medical specialists in a given community.

Catchment Area, Health↗
PubMed1985

1,4-Bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) and related compounds as inducers of hepatic monooxygenases. Structure-activity effects.

1,4-Bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) resembles phenobarbital (PB) in its mode of induction of the hepatic drug-metabolizing enzymes in mice. The structural features of this molecule include: a linear tricyclic aromatic ether ring system, an internal 1,4-disubstituted benzene ring and two 3,5-dichloropyridyloxy substituents. Ten analogs of TCPOBOP have been synthesized and their activities as microsomal enzyme inducers evaluated. Dose-response induction of mice hepatic microsomal cytochrome P-450, aldrin epoxidase and dimethylaminoantipyrine N-demethylase gave ED50 values for TCPOBOP and five homologs. The results illustrate that changes in the structure of the pyridyloxy ring markedly affect enzyme induction activity. The order of activity for the substituents was 3,5-dibromopyridyloxy approximately 3,5-dichloropyridyloxy greater than 5-bromopyridyloxy approximately 5-chloropyridyloxy greater than 3-chloropyridyloxy greater than pyridyloxy. In addition, the effects of altered substitution pattern of the benzene ring and structural alterations of the internal ring moiety were evaluated by measuring hepatic microsomal coumarin hydroxylase activity. The results confirm the microsomal monooxygenase enzyme induction activity of TCPOBOP, and the observed structure-dependent potencies of several related homologs support a receptor-mediated mechanism of action for the process.

Animals↗
PubMed1985

Factors that affect the HMO enrollment decision: a tale of two cities.

Although there is agreement that utilization patterns in HMOs differ from those in non-HMO systems, there is less agreement on how and why these differences are achieved. Selection bias is one frequently offered explanation. In an attempt to identify those individual and site-specific factors that help determine employees' choice of coverage, we developed and tested a logistic model of the enrollment decision. We used both survey data and claims data to study the decision to enroll in either an HMO or a traditional indemnity plan among state employees in Tallahassee, Florida, and Salt Lake City, Utah. We found that many factors affected the decision--factors that could be altered by an HMO or insurance company to correct selection bias if and when it is encountered.

Adult↗
PubMed1984

PCBs and PBBs: biologic and toxic effects on C57BL/6J and DBA/2J inbred mice.

Treatment of genetically inbred "responsive" C57BL/6J and "non-responsive" DBA/2J mice with Aroclor 1254 or fireMaster BP-6 resulted in the induction of hepatic microsomal benzo[a]pyrene hydroxylase only in the former mouse strain and aminopyrine N-demethylase in both strains of mice. In contrast, 3,3',4,4',5-pentachlorobiphenyl and 3,3',4,4'-tetrabromobiphenyl, induced benzo[a]pyrene hydroxylase in both C57BL/6J and DBA/2J but did not enhance aminopyrine N-demethylase in either strain of mouse. Both these coplanar halogenated biphenyls also caused thymic atrophy in the responsive and non-responsive mice and their effects resembled those of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Treatment of the inbred mice with several mono-ortho substituted analogs of the coplanar halogenated biphenyls, including 2,3,3',4,4'-pentachloro-, 2,3',4,4',5-pentabromo-, 2,3,3',4,4',5-hexachloro- and 3',4'-dibromo-2,3,4,5-tetrachlorobiphenyl, gave hepatic enzyme-induction results similar to those observed for the commercial halogenated biphenyls. At dose levels of 1500 mumol/kg, most of these compounds caused thymic atrophy in C57BL/6J mice but not in DBA/2J mice. The structure-activity correlations in the mice complement similar studies with the halogenated biphenyls in rats and support the proposed receptor-mediated mechanism for the toxic halogenated aromatics.

Aminopyrine N-Demethylase↗
PubMed1983

An autopsy study of histologic progression in non-Hodgkin's lymphomas. 192 cases from the National Cancer Institute.

Histologic slides were reviewed from 192 autopsies of patients with non-Hodgkin's lymphomas admitted to the National Cancer Institute (NCI) from 1953 to 1975. Each autopsy was classified according to the systems of Rappaport and Lukes-Collins. Comparisons with the initial diagnosis were made. The initial histologic diagnoses of the autopsied population were similar in distribution to other published series of non-Hodgkin's lymphomas. Of the 56 cases which initially demonstrated nodular patterns of growth, the following distribution was found at autopsy: 25%, no lymphoma; 6%, nodular lymphoma; 32%, diffuse histiocytic (large cell) lymphoma (DHL); 21%, diffuse undifferentiated (non-Burkitt's) lymphoma (DUL); and 16%, the remaining diffuse morphologies. Of the 136 patients with initial diagnosis of diffuse lymphoma, the following distributions were observed at autopsy: 20%, no lymphoma; 0%, nodular lymphoma; 31%, diffuse histiocytic (large cell) lymphoma; 12%, diffuse undifferentiated (non-Burkitt's) lymphoma; 9%, Burkitt's tumor; 14%, diffuse poorly differentiated lymphocytic lymphoma; and 14%, the remaining diffuse morphologic types. One hundred and thirty-four cases which were initially diagnosed as follicular center cell type within the Lukes-Collins classification gave the following distribution at autopsy: 21%, no lymphoma; 25%, small noncleaved type; 17%, large noncleaved type; 23%, non-follicular center cell lymphomas (17% immunoblastic B); and the remaining 13% were distributed among the other follicular center cell types. This autopsy review demonstrates the rarity of nodular (follicular) lymphomas at autopsy, and the predominance of the diffuse histiocytic or "transformed" type. This study provides a comparison of the rate of histologic progression of lymphomas in the same patient population at autopsy with a previously published study of progression during life.

Adolescent↗
PubMed1981

Interferon-induced NK augmentation in humans. An analysis of target recognition, effector cell recruitment and effector cell recycling.

By combining a single-cell cytotoxicity assay in agarose with estimations of the maximal natural killer (NK) cell potential (Vmax) by 51Cr release, the mechanism behind interferon augmentation of human NK cells were analysed. The number of target-binding cells (TBCs) the fraction of active TBCs and NK cell recycling were studied after short-term interferon treatment. The results demonstrate a dual effect of interferon on human NK cells: effector cell recruitment and increased effector cell recycling. Both of these variables were increased when NK cells were tested against the standard target K-562 and against Daudi and BJAB cells, derived from B-type lymphomas. However, when T cell lines derived from acute lymphocytic leukaemia (Molt-4 and 1310) were used as targets, a larger fraction of active NK cells were found among untreated TBCs, whereas interferon treatment only resulted in increased effector cell recycling and not in effector cell recruitment. No increase in TBCs after interferon treatment could be detected with any cell line tested. The difference seen between T and non-T cell lines with regard to interferon-induced effector cell recruitment is discussed in relation to known characteristics of the human NK system.

Cell Fractionation↗
PubMed1981

Monocyte-induced human natural killer cell suppression followed by increased cytotoxic activity during short-term in vitro culture in autologous serum.

When normal human peripheral blood mononuclear cells were tissue-cultured in autologous serum under conditions permitting cell contact, spontaneous fluctuations in cytotoxic activity were found. An analysis demonstrated that monocytes have the capacity to suppress initially (days 1-2) natural killer (NK) activity and that, at later time points (days 3-7), cytotoxic activity against the NK-susceptible target cell Molt-4 occurs which increases above initial NK levels. The newly induced killing depended on adequate cell contact for its induction and correlated with spontaneous proliferation in the cultures. The monocyte-induced NK suppression was found to be independent of cell contact and inhibited by the presence of indomethacin, thus most probably mediated by secreted prostaglandins. Suppressed NK cells (at day 1) had a lower number of target-binding cells (TBCs) and a smaller fraction of active NK cells among TBCs as compared with control cells. The fluctuations in cytotoxicity as seen in the present in vitro system are discussed in relation to clinical conditions with decreased NK activity, such as multiple sclerosis and Hodgkin's disease.

Cell Communication↗
PubMed1976

Adriamycin and enhanced radiation reaction in normal esophagus and skin.

Clinical evaluation of 10 patients with small cell carcinoma of the lung treated with radiotherapy and periodic cycles of combination chemotherapy with cyclophosphamide, vincristine, and adriamycin showed frequent and occasionally severe esophageal and skin reactions. Eight of the 10 patients had esophagitis, four required supportive intravenous fluids, and two subsequently developed esophageal narrowing and stricture formation. Recurrent esophagitis with augmentation of injury in the recently irradiated esophagus was observed 11 times in eight of the 10 patients after cycles of chemotherapy, and contributed to the sustained toxicity seen in two patients. Dermatitis in the form of moist desquamation was observed in five of the patients at very low doses of supervoltage radiation therapy. Acute pulmonary reactions was notably absent. This combination of chemotherapy, particularly adriamycin, potentiates the effect of radiotherapy on the normal esophagus and skin, and further implicates the radiosensitizing property of adriamycin.

Carcinoma, Small Cell↗