Search PubMed⌕ Search

Biomedical subjects

M Taylor

Publications and source records attributed to M Taylor.

At least 469 records · Page 26Linked to original sources
PubMed1992

Glycosaminoglycan synthesis by cultured human hair follicle dermal papilla cells: comparison with non-follicular dermal fibroblasts.

The extracellular matrix of the hair follicle dermal papilla is rich in glycosaminoglycans, the expression of which varies during the hair growth cycle being maximal in anagen and becoming undetectable as the follicle enters telogen. These observations, together with other experimental and clinical evidence, suggest that glycosaminoglycans may be involved in regulating hair growth. To investigate the metabolism of glycosaminoglycans by the dermal papilla we have measured the incorporation of radiolabelled precursors into glycosaminoglycans released into extracellular matrix and culture medium by cultured human dermal papilla cells. We also studied glycosaminoglycan synthesis by cells cultured from the lower follicular connective tissue sheath and by non-follicular dermal fibroblasts. Compared with dermal fibroblasts, dermal papilla cells showed a three to fourfold higher level of incorporation of 35S-sulphate and 3H-glucosamine into extracellular matrix glycosaminoglycans. Dermal papilla cells also released more 3H-glucosamine-labelled glycosaminoglycan into culture medium than dermal fibroblasts but there was no difference in 35S-sulphate labelling. These findings indicate that dermal papilla cells maintain a high level of glycosaminoglycan synthesis in vitro. Specific enzyme/chemical degradation showed that dermal papilla cells and dermal fibroblasts synthesized the same glycosaminoglycan types. However, the results suggested that dermal papilla glycosaminoglycans are less sulphated than those synthesized by dermal fibroblasts and that a higher proportion of sulphated glycosaminoglycans is retained in an extracellular matrix. The synthesis of glycosaminoglycans by connective tissue sheath cells was similar to that of dermal papilla cells, supporting the view that the dermal papilla and connective tissue sheath share certain properties.

Cells, Cultured↗
PubMed1992

The effect of 3 mouthrinses on plaque and gingivitis development.

The aim of this study was to evaluate the effect of 3 mouthrinses, Listerine Antiseptic (thymol), Peridex (chlorhexidine), Perimed (povidone iodine and hydrogen peroxide), and a placebo (water) on the development of dental plaque and gingivitis, when used as the only oral hygiene procedure for 14 days. 71 subjects were entered into a randomized, double-blind study. At the baseline examination, papillary bleeding score (PBS), and plaque index (PI) were registered, after which subjects received supragingival prophylaxis and were assigned to 1 of 4 study cells. Subjects were asked to refrain from all oral hygiene procedures except for the supervised 14-day 2 x daily rinsing with the assigned preparation. At day 14, the same clinical parameters were again registered. Statistical analysis was performed by a one-way analysis of variance (ANOVA) to compare the 4 groups, followed by Duncan's multiple range test to determine specific group differences. At baseline, average PBS and PI scores were similar for all 4 groups. After 14 days, the average PBS for Peridex and Perimed was significantly lower than for Listerine Antiseptic and water. The frequency of interdental units with a PBS greater than 2 was significantly lower for Peridex and Perimed than for Listerine Antiseptic and water. We concluded that both Peridex and Perimed were effective in reducing plaque and gingivitis when used as a 2 x daily mouthrinse by subjects refraining from other oral hygiene procedures. In vitro, a synergistic effect was assumed when inhibition was achieved with Perimed at the same or greater dilution than was achieved with povidone-iodine alone.

Actinomyces viscosus↗
PubMed1992

Necrobacillosis with pancytopenia.

Two young children whose presentation with necrobacillosis caused considerable diagnostic difficulty resulting in referral to an oncology unit are described. In both cases their severe suppurative multisystem illness was complicated by pancytopenia. One had bone marrow infarcts and severe endocarditis in addition to pulmonary involvement and the other had osteitis which resulted in a deformed humerus.

Anti-Bacterial Agents↗
PubMed1992

Linkage analysis of insulin-receptor gene in familial NIDDM.

Although non-insulin-dependent diabetes mellitus (NIDDM) is clearly inherited, the mode of inheritance and genetic etiology remain unknown. Impaired insulin action is an important component of NIDDM, which may precede NIDDM onset, and appears to be inherited. Numerous defects of the insulin-receptor gene have been described in syndromes of extreme insulin resistance, and this gene is a strong candidate for genetic predisposition to NIDDM. To test this hypothesis, we examined 18 white pedigrees from Utah that had two or more siblings with NIDDM. For each pedigree, individuals not known to be affected were tested by standard oral glucose tolerance test, and diagnoses of NIDDM and impaired glucose tolerance were made by World Health Organization criteria. Each individual was typed for seven restriction-fragment-length polymorphism markers at the insulin-receptor locus, and marker phase was established by segregation. Linkage was examined with the LINKAGE program under six models, including autosomal dominant and autosomal recessive, with individuals with impaired glucose tolerance counted either as affected or of unknown status and with or without sporadic cases of diabetes. Under each model, linkage was significantly rejected. Neither inspection of individual pedigree log of odds scores nor formal tests of heterogeneity suggested a subgroup in which linkage of NIDDM and insulin-receptor gene was likely. In addition, sharing of insulin-receptor gene haplotypes among 108 affected sibling pairs drawn from the pedigrees did not deviate from that expected by chance alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Long-term increases in excitability in the CA1 region of rat hippocampus induced by beta-adrenergic stimulation: possible mediation by cAMP.

The cellular mechanisms underlying beta-adrenergic potentiation in the CA1 region of the rat hippocampus were examined. A 10 min treatment with isoproterenol (ISO) induced a long-term depolarization of the pyramidal neurons that persisted for at least 30 min of washout; the ISO-induced decrease in the calcium-activated potassium conductance (afterhyperpolarization, or AHP) was similarly prolonged. The long-term excitability changes induced by ISO did not depend upon the calcium concentration of the medium and could be elicited in medium containing as little as 240 microM calcium. The persistent increase in population spike induced by ISO was mimicked by superfusion with several cAMP analogs and by forskolin (which directly activates adenylate cyclase), but not by the inactive dideoxyforskolin. Forskolin and cAMP analogs also induced decreases in AHPs that could be quite prolonged, but did not depolarize pyramidal neurons as consistently as did ISO. We hypothesize that activation of beta-adrenergic receptors in the CA1 region of hippocampus may induce an alteration of the hippocampal "state" that can persist for as long as several hours, during which the induction of other forms of plasticity may be enhanced.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Streptozotocin-induced diabetes and the effects of endurance exercise training.

The purpose of this investigation was to determine if endurance exercise training would alter the degenerative effects of streptozotocin diabetes on cardiac function and alter the responses of streptozotocin diabetic rats to induced myocardial ischemia. Diabetic rats experienced a significant (p < 0.05) reduction in cardiac function as evidenced by left ventricular peak systolic pressure (LVPSP), maximal time rate of change of pressure (+dP/dTmax), rate pressure product (RPP), and heart rate (HR). Exercise training apparently reduced the effect of diabetes since the function of non-ischemic hearts from trained diabetic rats was not different from that of non-diabetic rats. It also was not different from the sedentary diabetic rat hearts. Training did not alter the response of the hearts of either group of diabetic rats to induced myocardial ischemia.

Analysis of Variance↗
PubMed1991

Characterization of muscarinic receptors mediating release of epithelial derived relaxant factor (EpDRF) in guinea-pig isolated trachea.

Muscarinic receptors mediating the release of epithelial derived relaxant factor (EpDRF) have been studied by using both contractions of the guinea-pig tracheal strip (with epithelium intact or denuded) or a coaxial bioassay assembly (rat anococcygeus-recipient; guinea-pig trachea-donor tissue). Indomethacin (1 microM/1) and physostigmine (0.1 microM/1) were both present throughout the study. In the tracheal strip studies, the potencies and maximal effects of all agonists studied (acetylcholine, arecoline, bethanechol, carbachol, (+)cis-dioxolane, ethoxyethyltrimethylammonium, L-660,863, (+/-)methacholine and OXA-22) were not affected or were only slightly (but significantly) reduced by removal of the epithelium. The -log KB for the muscarinic antagonists, atropine, pirenzepine, methoctramine and 4-DAMP (4-diphenyl-acetoxy-N-methylpiperidine) were also not affected and the -log KB values were consistent with M3 muscarinic receptor function. However, the -log KB value of para-fluoro-hexahydro-siladifendol (p-F-HHSiD) was significantly (P less than 0.05) increased upon epithelial denudation (epithelium intact, 7.1; epithelium removed, 7.6). The coaxial bioassay assembly provided more convincing evidence for release of EpDRF in that all muscarinic agonists studied caused relaxations of a precontracted anococcygeus tissue. These relaxations were observed only in the presence of a tracheal tube possessing an intact epithelium. The rank order of potencies for agonists at receptors mediating EpDRF dependent relaxation were similar to those estimated at receptors causing contraction. These data suggested that a substantial receptor reserve was associated with the receptors mediating both EpDRF release and contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Characterization of a new cell line (ESKOL) resembling hairy-cell leukemia: a model for oncogene regulation and late B-cell differentiation.

A B-lymphoblastoid cell line ESKOL, composed of differentiated cells resembling hairy-cell leukemia (HCL) has been established from the peripheral blood (PB) of a HCL patient. Morphologically, ESKOL cells share several features with HCL B cells. Flow cytometric analysis revealed that ESKOL cells express HC2, CD21, PCA-1, CD24, FMC7, and CD25. Analysis by Northern-blot hybridization indicated that cultured cells expressed the oncogenes c-myc, H-ras and c-fos. RNA from 3T3 cells transfected with ESKOL DNA hybridized with H-ras and c-fos DNA probes. The ESKOL cells cultured in the presence of increasing concentrations, of alpha interferon demonstrated a decrease in the rate of cellular growth and an increase in the expression of CD21, CD25, FMC7 and PCA-1. Scanning electron microscopy revealed that cells incubated in the presence of alpha interferon underwent membranous changes with a loss of villosity. These observations suggest that IFN tends to drive HC out of their developmental arrest towards maturation.

Aged↗
PubMed1991

Characterization of an expressible nonclassical class I HLA gene.

Screening of a human cosmid library representing genomic DNA from an individual homozygous for the HLA-DR2 B7 A2 haplotype yielded 109 class I HLA-specific clones. One cosmid clone, Ice 6.23, had a full-length nonclassical class I gene within a 5.4-kb HindIII fragment. The Ice 6.23-5.4H gene was cloned into the unique NotI site of an expression vector pSV2.Not, a derivative of pSV2neo, which was constructed to contain a second SV40 early region promoter adjacent to an introduced NotI site. The resulting construct was transfected into the P815-B2M cell line, a derivative of the mouse mastocytoma P815 (HTR) line which expressed human beta2-microglobulin following stable transfection with a cloned human beta2-microglobulin gene. Following transfection the Ice 6.23-5.4 H gene was found to be expressed at both the mRNA and cell surface product levels. DNA sequencing of this gene suggests that it is allelic to the HLA-6.0 gene clone (HLA-G) of Geraghty et al. (Proceedings of the National Academy of Sciences USA, 84:9145, 1987); thereby revealing a HindIII restriction fragment length polymorphism at the HLA-G locus. An extraordinarily high degree of sequence similarity (99.92%) between these two genes, which derive from unrelated HLA haplotypes, suggests strong conservative selection pressure at the HLA-G locus. A flanking single copy sequence probe 4 kb distant from the Ice 6.23-5.4H gene was used to generate long-range restriction mapping at the HLA-G locus.

Amino Acid Sequence↗
PubMed1991

Effects of dietary supplementation on work performance in Gambian laborers.

The effect of food supplementation on productivity of Gambian subsistence farmers was studied during a natural food shortage induced by the annual hungry season. Sixteen men in two groups matched for weight, height, hemoglobin, and physical-work capacity followed a crossover protocol with 6-wk supplementation and control periods. Productivity was assessed over the final 3 wk of each period by quantifying piece-rate-paid road building. Supplementation comprised an ad libitum supply of highly palatable energy-dense food provided three times daily. Outcome variables were total loads transported, loads per working hour, time per load, total energy expenditure assessed by doubly labeled water and heart-rate monitoring, postwork activity, and anthropometry. Body weight decreased during control periods, indicating a real energy deficit, and increased during supplementation in both groups. Supplementation had no significant impact on productivity variables. Energy-deficient men can maintain maximal productivity over short periods if sufficiently motivated but at the expense of body weight.

Adult↗
PubMed1991

Reproducibility of attachment level measurements with two models of the Florida Probe.

Clinical assessment of the progression of periodontitis is based on the measurement of periodontal probing attachment levels over time. In calculating these changes, duplicate measurements from fixed reference points, including cemento-enamel junctions and acrylic stents, have been used to assist in detecting progressive disease. The Florida Probe has been previously shown to improve the reproducibility of these measurements when used with an acrylic stent. The objective of the present study was to evaluate the reproducibility of 2 models of the Florida Probe, the original stent model and the modified disk model, in measuring attachment level. The disk probe differs from the stent probe in that it uses the occlusal surface of the tooth as a static reference point in calculating changes in attachment level measurements. In 10 subjects, sites were probed 2 x by 2 examiners using both types of probe. Standard deviations and intra- and inter-examiner correlations were calculated. These results demonstrate that the new disk probe yields reproducible measurements similar to the stent probe and is therefore suitable for use in longitudinal clinical studies.

Equipment Design↗
PubMed1991

Intussusception in cystic fibrosis.

Two cases of acute intussusception in older children with cystic fibrosis are reported. Both cases presented with symptoms and signs consistent with meconium ileus equivalent, which delayed the final diagnosis. Both cases required abdominal surgery but made full and uneventful recoveries.

Cystic Fibrosis↗