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Biomedical subjects

M Collins

Publications and source records attributed to M Collins.

At least 127 records · Page 7Linked to original sources
PubMed1996

Bridging the research-practice gap: the role of the link nurse.

This article describes the gap between research and practice, and highlights an initiative at Rampton Hospital to bridge this gap through the introduction of ward-based link people. The authors outline the rationale behind the initiative and describe in detail how the strategy was put into practice.

Humans↗
PubMed1996

Functional analysis of aquaporin-1 deficient red cells. The Colton-null phenotype.

The aquaporin-1 (AQP1) water transport protein contains a polymorphism corresponding to the Colton red blood cell antigens. To define the fraction of membrane water permeability mediated by AQP1, red cells were obtained from human kindreds with the rare Colton-null phenotype. Homozygosity or heterozygosity for deletion of exon I in AQP1 correlated with total or partial deficiency of AQP1 protein. Homozygote red cell morphology appeared normal, but clinical laboratory studies revealed slightly reduced red cell life span in vivo; deformability studies revealed a slight reduction in membrane surface area. Diffusional water permeability (Pd) was measured under isotonic conditions by pulsed field gradient NMR. Osmotic water permeability (Pf) was measured by change in light scattering after rapid exposure of red cells to increased extracellular osmolality. AQP1 contributes approximately 64% (Pd = 1.5 x 10(-3) cm/s) of the total diffusional water permeability pathway, and lipid permeation apparently comprises approximately 23%. In contrast, AQP1 contributes > 85% (Pf = 19 x 10(-3) cm/s) of the total osmotic water permeability pathway, and lipid permeation apparently comprises only approximately 10%. The ratio of AQP1-mediated Pf to Pd predicts the length of the aqueous pore to be 36 A.

Aquaporin 1↗
PubMed1996

Health education about sun and skin cancer: language, ideas and perceptions of young children.

Excessive sunlight in early childhood is thought to be a risk factor for skin cancer. We report the use of the 'draw and write' technique for determining changing perceptions, attitudes and knowledge of young children (aged 4-12 years) to the sun and skin cancer. Children were asked to draw pictures and label them in response to a series of carefully worded invitations and questions. The captions were then analysed to assess changing views and perceptions about particular issues in relation to behaviour in the sun. Four hundred and sixty children completed the exercise. An increasing spiral of knowledge with age about effects of the sun and appropriate behaviour was demonstrated. The study revealed a relatively high level of knowledge. Misconceptions and stereotypes were demonstrated. This technique is a simple and effective way of eliciting information from children about health issues. It provides baseline data for producing material for health education for children in relation to sun and skin. It is also a method of assessing the effectiveness in young children of health promotion initiatives.

Art↗
PubMed1996

Primary school children's perceptions of the effects of sun on skin.

To assess whether young children understand the dangers and results of sun exposure, a novel Draw and Write technique was used to survey a group of 5-8 year old primary school children. One hundred and ninety-four children were invited to draw and write comments to six scenarios involving sun exposure. Of the children surveyed, 84% gave a negative sentiment to sunburn, with only 6% displaying positive sentiments towards sunbathing. Sixty-five per cent of children suggested the use of sun blocks, 69% the use of protective clothing, 45% the wearing of hats and 43% the use of shade as a mechanism for protecting the skin from sun damage. Only 2% of children made any reference to skin cancer. The primary school children surveyed had a good level of awareness of the dangers of sunburn and the need to take appropriate actions to avoid sun damage.

Attitude to Health↗
PubMed1996

An enhanced-sensitivity branched-DNA assay for quantification of human immunodeficiency virus type 1 RNA in plasma.

The quantification of human immunodeficiency virus type 1 (HIV-1) RNA has facilitated clinical research and expedited the development of antiretroviral drugs. The branched-DNA (bDNA) assay provides a reliable method for the quantification of HIV-1 RNA in human plasma and is considered one of the most reproducible assays ready for use in clinical trials. A series of oligonucleotide probe design and solution changes have been developed to enhance the sensitivity of the bDNA assay while maintaining its performance characteristics. Among the changes incorporated into the enhanced-sensitivity bDNA (ES bDNA) assay to reduce the background level and enhance the signal are the use of shorter overhang sequences of target probes for capture, the cruciform design of target probes for amplification, and the addition of preamplifier molecules. The ES bDNA assay is at least 20-fold more sensitive than the first-generation bDNA assay, yet it maintains a high level of accuracy, linearity, and reproducibility. Further, quantification values obtained with the ES bDNA assay and the first-generation bDNA assay are highly correlated, thus allowing for meaningful comparisons of HIV-1 RNA levels in specimens tested with either assay. The ES bDNA assay may be useful in determining the prognostic value of HIV-1 RNA levels of below 10,000 copies per ml and in assessing the clinical benefit of antiretroviral therapy-induced decreases in plasma HIV-1 RNA sustained at levels of below 10,000 copies per ml.

Anti-HIV Agents↗
PubMed1996

Accurate quantification of hepatitis C virus (HCV) RNA from all HCV genotypes by using branched-DNA technology.

In studies monitoring disease progression and therapeutic response, it is essential that the method used for hepatitis C virus (HCV) quantification not be influenced by genotypic variability. The branched DNA assay provides a reliable method for the quantification of HCV RNA. A modified set of oligonucleotide probes for the branched DNA assay was developed to enhance the efficiency of binding to genotypic variants of HCV. The improved branched DNA assay (HCV RNA 2.0) yielded highly reproducible quantification of hepatitis C virus RNA and displayed a nearly 600-fold dynamic range in quantification up to 120 Meq of HCV RNA per ml. The quantification limit was set at 0.2 Meg of HCV RNA per ml to ensure a specificity of > or = 95%. With this lowered quantification limit and the enhanced hybridization of the probes, the HCV RNA 2.0 assay exhibited a high level of sensitivity (96%) and was virtually unaffected by the genotypic variability of HCV. The HCV RNA 2.0 assay may be a useful tool for following HCV RNA levels throughout the course of disease, selecting patients for therapy, and evaluating therapeutic response.

Base Sequence↗
PubMed1996

Phosphaturic effect of L-NMMA in the presence of parathyroid hormone.

The objective of this study was to examine the effect of NG-monomethyl-L-arginine (L-NMMA) on phosphate excretion in the presence and absence of parathyroid hormone (PTH). Renal clearances were obtained before and during infusion of L-NMMA (15 mg/kg bolus and 500 micrograms.kg-1.min-1 infusion) in Sprague-Dawley rats with intact parathyroid glands (n = 6), in thyroparathyroidectomized (TPTX) rats receiving a constant infusion of PTH-(1-34) (0.01-0.03 U.kg-1.min-1) (n = 11) throughout the experiment, or in TPTX rats, that received an acute infusion of PTH-(1-34) (33 U/kg bolus and 1 U.kg-1.min-1 infusion) after L-NMMA infusion alone (n = 7). In rats with intact parathyroid glands, L-NMMA increased the fractional excretions of phosphate (FEPi) and sodium (FENa) and mean arterial pressure (MAP) (delta 8.6 +/- 1.5%, delta 0.62 +/- 0.1%, and delta 26.7 +/- 4.9 mmHg, respectively; P < 0.05). In TPTX rats receiving a constant infusion of PTH, L-NMMA again increased FEPi, FENa, and MAP (delta 9.5 +/- 3.6%, delta 1.1 +/- 0.4%, and delta 28.4 +/- 4.5 mmHg, respectively; P < 0.05). However, in TPTX rats, L-NMMA alone did not increase FEPi (delta 0.9 +/- 0.3%), whereas the subsequent infusion of PTH with L-NMMA increased FEPi (delta 15.6 +/- 3.1%; P < 0.05). In an additional group of intact and TPTX rats, the fractional excretion of lithium (FELi) was measured as an index of proximal reabsorption. L-NMMA increased FELi in intact rats (delta 13.2 +/- 2.6%; P < 0.05), but not in TPTX rats (delta 4.2 +/- 3.3%). In conclusion, L-NMMA increases phosphate excretion in association with increases in MAP and FENa, and this phosphaturic effect is dependent on the presence of PTH.

Animals↗
PubMed1996

Inhibition of plasminogen activator inhibitor-1 activity by two diketopiperazines, XR330 and XR334 produced by Streptomyces sp.

Two diketopiperazines, XR334 (1) and the novel compound XR330 (2), were isolated from the lyophilised biomass of an unidentified Streptomyces sp. Their structures were elucidated on the basis of spectroscopic studies and confirmed by chemical synthesis. Both compounds inhibited plasminogen activator inhibitor-1 activity in an amidolytic assay of tissue plasminogen activator mediated plasmin generation. Compound 1 also enhanced fibrinolysis ex vivo and protected against thrombus formation in the rat. These diketopiperazines represent the first low molecular weight inhibitors of plasminogen activator inhibitor-1, a physiological regulator of fibrinolysis.

Animals↗
PubMed1996

The corporate practice of health care ... a panel discussion.

The pros and cons of treating health care as a profit-making business got a lively airing in Boston May 16, when the Harvard School of Public Health's "Second Conference on Strategic Alliances in the Evolving Health Care Market" presented what was billed as a "Socratic panel." The moderator was Charles R. Nesson, J.D., a Harvard Law School professor of 30 years' standing whose knack for guiding lively discussions is well known to viewers of such Public Broadcasting Service series as "The Constitution: That Delicate Balance. "As one panelist mentioned, Boston was an interesting place for this conversation. With a large and eminent medical establishment consisting mostly of traditionally not-for-profit institutions, the metropolis of the only state carried in 1972 by liberal Presidential candidate George McGovern is in one sense a skeptical holdout against the wave of aggressive investment capitalism that has been sweeping the health care industry since the 1994 failure of the Clinton health plan. In another sense, though, managed care-heavy Boston is an innovative crucible of change, just like its dominant HMO, the not-for-profit but merger-minded Harvard Pilgrim Health Care. Both of these facets of Beantown's health care psychology could be discerned in the comments heard during the panel discussion. With the permission of the Harvard School of Public Health--and asking due indulgence for the limitations of tape-recording technology in a room often buzzing with amateur comment--MANAGED CARE is pleased to present selections from the discussion in the hope that they will shed light on the business of health care.

Community-Institutional Relations↗
PubMed1995

Transfection of TCR alpha-chains into suppressor and T helper cell hybridomas. Production of suppressor factors with predicted antigen specificity.

Conditioned medium from Ag-specific suppressor T cell hybridomas contains soluble factors (TsF) that modulate immune responses in an Ag-specific manner. We previously generated a series of TCR-alpha- and TCR-beta- expression variants from a 4-hydroxy-3-nitrophenyl acetyl (NP)-specific inducer suppressor T cell hybridoma and demonstrated that loss of TCR alpha-chain mRNA, but not TCR-beta chain mRNA, was accompanied by concomitant loss of suppressor bioactivity. Suppressor factor bioactivity was restored by expression of TCR alpha-chain cDNA, suggesting that the TCR alpha-chain plays a critical role in Ag-specific suppressor cell function. We have now transfected TCR alpha-chain from a Th cell clone specific for arsanylated peptides plus I-Ad into a TCR-alpha- derivative of an NP-specific inducer suppressor T cell hybridoma. The transfectants expressed a new hybrid TCR-alpha beta complex and produced soluble factors that suppressed azobenzenearsonate hapten (ABA) but not NP delayed-type hypersensitivity responses. These supernatants mediated suppression of the induction, but not the effector phase of the delayed-type hypersensitivity reaction. In reciprocal experiments we transfected a TCR alpha-chain from an NP-specific suppressor T cell hybridoma into a TCR-alpha- hybridoma derived from the ABA-specific Th cell hybridoma. The NP-specific TCR alpha-chain was expressed in the Th cell hybridoma, but the supernatant from this transfectant did not suppress DTH responses to either NP or ABA. However, the latter supernatants, when combined with cell lysates derived from a TCR-alpha- Ts hybridoma, specifically suppress NP DTH responses. These data are consistent with the interpretation that TCR alpha-chain imparts Ag specificity to the suppressor molecule and a second, yet undefined, component produced by the Ts hybridoma controls the immunoregulatory bioactivity.

Animals↗
PubMed1995

T cell receptor alpha-chain defines the antigen specificity of antigen-specific suppressor factor but does not impart genetic restriction.

Previous studies utilizing NP (4-hydroxy, 3-nitrophenyl acetyl hapten)-specific, T suppressor hybridomas have indicated that expression of TCR-alpha, but not TCR-beta, mRNA is required for expression of Ag-specific suppressor factor bioactivity. Suppressor-effector factor has been shown to be Ag specific and I-J restricted. Although the expression of TCR-alpha mRNA was necessary for suppressor activity, the role of TCR-alpha, as it pertained to the functional properties of T cell suppressor factor (TsF), was not established. To determine which properties of TsF could be accounted for by TCR-alpha expression, TCR-alpha cDNA, derived from NP-specific, suppressor T cell (Ts) hybridomas, was transfected into recipient Ts hybridomas of a second Ag specificity. The resulting heterologous transfectants displayed NP-specific, genetically restricted TsF activity. The Ag specificity corresponded to that of the TCR-alpha donor; however, the genetic restriction was influenced by the recipient cell, implying that TCR-alpha did not control genetic restriction of the TsF. Examination of TCR-beta expression in one of the MHC-restricted transfectants indicated that the genetic restriction of TsF could not be accounted for by TCR-beta gene products. The data support the conclusion that TCR-alpha expression is not only obligate for TsF bioactivity, but that the Ag specificity of the TCR-alpha dictates the Ag specificity of the resulting suppressor factor.

Animals↗