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Biomedical subjects

J Merrill

Publications and source records attributed to J Merrill.

At least 37 records · Page 2Linked to original sources
PubMed1991

Detection of lymphocyte subsets using three-color/single-laser flow cytometry and the fluorescent dye peridinin chlorophyll-alpha protein.

The fluorescent dye, Peridinin chlorophyll A protein (PerCP) derived from dinoflagellate organisms (Glenodinium sp.) can be excited by a 488 nm laser and emits light with a large Stokes shift and no major spectral overlap with commonly used chromophores such as fluorescein isothiocyanate (FITC) and R-phycoerythrin (PE). PerCP was conjugated directly to various mouse monoclonal antibodies (mAb) specific for human leukocyte markers or to avidin for use with biotinylated-mAb, and used to perform three color single-laser flow cytometry. The efficacy of this method was demonstrated by analyzing the heterogeneity of thymus T lineage subsets and B lymphocyte subsets in blood. CD4-CD8-, CD4+CD8+ and CD4+CD8- or CD4-CD8+ subsets differ in their expression of cell-cell interaction markers including CD18, CD28, CD44 and Leu 8, and activation/subset markers CD45RO, CD45RA and CD26. Some CD5+ peripheral blood B cells, unlike CD5-B cells, expressed CD45RO or high levels of CD54 (ICAM-1) suggesting the CD5+ B cell population contains activated lymphocytes. The availability of such an accessible method for three color analysis will make it possible to do routine three color monitoring of immunologic diseases such as AIDS, and autoimmune or periodontal diseases.

Antibodies, Monoclonal↗
PubMed1991

Structural elements that regulate pp59c-fyn catalytic activity, transforming potential, and ability to associate with polyomavirus middle-T antigen.

Except for its unique amino-terminal region (residues 1 through 83), which possibly dictates substrate recognition, pp59c-fyn bears a high degree of homology with other members of the src family of tyrosine kinases. Here we show that the carboxy terminus of pp59c-fyn is necessary for stable middle-T-antigen association, that pp59c-fyn is normally phosphorylated on both serine and tyrosine residues, and that Tyr-531 and Tyr-420 are phosphorylation sites in vivo and in vitro, respectively. Analysis of a spontaneously generated mutant encoding a truncated form of pp59c-fyn and of variants specifically mutated at the Tyr-531 and Tyr-420 phosphorylation sites indicates that pp59c-fyn has regulatory elements analogous to those that have already been identified for other src-like tyrosine kinases. However, further examination of the pp59c-fyn variants suggests the likelihood of additional means by which its activities might be regulated. Although alteration of Tyr-531 to phenylalanine (531F) in pp59c-fyn results in a protein which is more active enzymatically that the wild type, the enhancement is much less than that for the analogous variant of pp60c-src. Furthermore, contrary to results of similar experiments on other src-like proto-oncogene products, 531F did not induce transformation of NIH 3T3 cells. Studies involving pp59c-fyn-pp60c-src chimeras in which the unique amino-terminal sequences (residues 1 through 83) of the two kinases were precisely interchanged implied that the inability of 531F to induce transformation is probably not caused by the absence of substrates for pp59c-fyn in NIH 3T3 cells but rather by the insufficient enhancement of pp59c-fyn kinase activity. It is therefore probable that the kinase and transforming activities of pp59c-fyn are repressed by additional regulatory elements possibly located in the amino-terminal half of the molecule.

Amino Acid Sequence↗
PubMed1991

CSF and endocrine studies of premenstrual syndrome.

Eight women with prospectively documented premenstrual syndrome (PMS) underwent multiple samplings for estradiol, progesterone, prolactin, cortisol, and plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) during an asymptomatic midcycle (late follicular) and a symptomatic premenstrual (late luteal) phase of the menstrual cycle. Cerebrospinal fluid (CSF) was collected for analysis of MHPG, norepinephrine (NE), 5-hydroxyindoleacetic acid (5-HIAA), dihydroxyphenylacetic acid (DOPAC), gamma-aminobutyric acid (GABA), homovanillic acid (HVA), tyrosine, tryptophan, beta-endorphin, prostaglandins, adrenocorticotropic hormone (ACTH), and arginine vasopressin (AVP). In subsequent months, a dexamethasone suppression test (DST) and a thyrotropin-releasing hormone (TRH) stimulation test were performed during midcycle and premenstrual phases. Significant results included increased CSF concentrations of MHPG in the premenstrual, as compared with the midcycle, phase of the cycle, and increased plasma cortisol concentrations during the midcycle phase. The DST showed a 62% overall rate of nonsuppression, irrespective of menstrual cycle phase. Though there were no abnormalities of thyrotropin-stimulating hormone (TSH) after TRH stimulation, the mean delta maximum prolactin values after TRH stimulation were higher than reported normal values both at midcycle and premenstrually. These pilot data suggest hormonal axes that might be worthy of further systematic investigation in future studies of PMS.

Adult↗
PubMed1990

Interleukin 6 is essential for antibody secretion by human in vivo antigen-induced lymphoblastoid B cells.

In vivo immunization of normal subjects with a variety of antigens generates circulating lymphoblastoid (LB) B cells, which in vitro spontaneously secrete significant levels of specific antibody. Since activation and initial differentiation of these cells occurs in vivo, they provide a useful model for the study of the later stages of B cell maturation. In the present study, we investigated the requirement of interleukin 6 (IL-6) for the "spontaneous" in vitro production of IgG-Tet by LB B cells. Addition of IL-6 to cultures of LB B cells in medium supplemented with 10% fetal calf serum failed to increase the levels of IgG-Tet produced in vitro. However, addition of anti-IL-6 antibodies decreased IgG-Tet production as much as 70%, and this inhibition could be reversed by the addition of IL-6. LB B cells cultured in serum-free medium in order to restrict endogenous IL-6 production secreted only low levels of antibody, unless exogenous IL-6 was added. Addition of 2.5 units/ml of IL-6 to serum-free cultures induced an increase in IgG-Tet secretion nearly comparable to that seen in cultures supplied with serum. The magnitude of the increase in IgG-Tet secretion in response to exogenous IL-6 was inversely related to the number of cells in culture, which was due in part to increased endogenous IL-6 production in cultures with higher cell concentrations. Experiments including hydroxyurea in serum-free cultures indicated that IL-6-dependent enhancement of LB B cells' IgG-Tet secretion was not primarily mediated by cell growth. These observations suggest that in vivo generated LB B cells are not totally committed to antibody secretion, and that IL-6 is essential for in vivo antigen-induced LB B cells to reach the antibody-secreting stage.

Antibodies↗
PubMed1990

Lipopolysaccharide from Actinobacillus actinomycetemcomitans stimulates macrophages to produce interleukin-1 and tumor necrosis factor mRNA and protein.

Actinobacillus actinomycetemcomitans is associated with periodontal disease in children and adults. We report that low concentrations of lipopolysaccharide (LPS) from A. actinomycetemcomitans stimulated human macrophages to increase dramatically their accumulation of mRNA coding for interleukin-1 alpha (IL-1 alpha), IL-1 beta as well as tumor necrosis factor (TNF). Protein levels of IL-1 and TNF alpha also increased. Levels of these mRNAs increased by 4-5 fold as compared with unstimulated macrophages when these cells were cultured with as little as 2 ng/ml LPS from A. actinomycetemcomitans. Polymyxin binds and blocks the action of LPS; polymyxin inhibited the ability of LPS from A. actinomycetemcomitans to increase levels of IL-1 beta mRNA. The LPS of A. actinomycetemcomitans stimulated increased levels of IL-1 beta mRNA in the presence of cycloheximide, showing that stimulation by this LPS did not require new synthesis of protein. Furthermore, dexamethasone inhibited the ability of LPS from A. actinomycetemcomitans to stimulate the accumulation of mRNA coding for IL-1 beta. A. actinomycetemcomitans is an invasive microorganism of the gingiva; high intragingival numbers correlate with sites undergoing local destruction of the periodontium. IL-1 alpha, IL-1 beta, and TNF are potent monokines that mediate inflammation and resorption of bone. Out studies suggest that macrophages migrating to these gingival sites of A. actinomycetemcomitans infection will be stimulated by LPS of A. actinomycetemcomitans to produce IL-1 alpha, IL-1 beta and TNF. These cytokines will mediate gingival inflammation and stimulate resorption of alveolar bone.

Actinobacillus↗
PubMed1990

Age and attempted suicide.

Clinical and demographic factors associated with suicide attempts admitted to the West Midlands Poisons Unit over a 2-year period were compared by age group. Risk factors for future suicide (living alone, physical illness, psychiatric illness and high suicidal intent in the attempt) were significantly more common among elderly patients (65 years and over) than middle-aged patients (35-64 years) and significantly less common among young patients (under 35 years) than middle-aged patients. Elderly patients that attempted suicide resemble elderly patients that completed suicide and should be considered at high risk of future suicide.

Adult↗
PubMed1990

Aging in place: a dilemma for retirement housing administrators.

The phenomenon of aging in place poses fundamental questions for administrators and planners of housing for the elderly. Based on a planning study for one retirement facility in the upper Midwest, we reviewed current knowledge pertinent to aging in place and present the findings of interviews with 13 housing administrators and present some limited market analysis of the host community of the subject retirement facility.

Activities of Daily Living↗
PubMed1990

Asian suicides.

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Adult↗
PubMed1988

Self-poisoning among four immigrant groups.

Rates of deliberate self-poisoning in four immigrant groups, Asian, West Indian, Irish and Scottish were compared with those of English-born residents in an inner-city area of Birmingham. For both Asian and West Indian groups males and older females were underrepresented but young females had rates similar to the English group. Irish females and Scottish of both sexes were overrepresented. The rates of self-poisoning for all four immigrant groups considerably exceeded those of their country of origin, the difference being most marked among young Asian females. Explanations for these findings are examined.

Adolescent↗
PubMed1987

Ethnic differences in self-poisoning. A comparison of West Indian and white groups.

The characteristics of West Indian patients admitted to a Birmingham hospital following deliberate self-poisoning were compared with those of White self-poisoners. West Indian patients were more likely to be young, female and single. They were less likely to have previously self-poisoned, have received previous psychiatric treatment, or be suffering from a personality disorder or alcoholism, but were more often followed-up by a social worker. Rates of self-poisoning for those aged under 25 were similar but for those aged over 25 were lower for West Indians than Whites.

Adolescent↗
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↗