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Biomedical subjects

M Davies

Publications and source records attributed to M Davies.

At least 235 records · Page 13Linked to original sources
PubMed1995

Metalloproteinase generation by human glomerular epithelial cells.

In the present study cultured human glomerular epithelial cells (HGEC) were used to examine the potential role for these cells in the turnover of the glomerular basement membrane (GBM) through the secretion of matrix metalloproteinases. The cells were shown by substrate gel electrophoresis to secrete gelatinase activity of molecular weights 72 kDa and 92 kDa. The gelatinolytic activity was inhibited by EDTA (10 mM), and by both TIMP-I and TIMP-II, but was not inhibited by PMSF (2.5 mM), indicating that the enzymes belonged to the metalloproteinase family. The identity of the enzymes was confirmed by the use of specific antisera to gelatinase A and gelatinase B. In addition, reverse transcription polymerase chain reaction (RT PCR) amplification of HGEC mRNA using specific primers to the two enzymes yielded single bands of amplified DNA and served to verify the identity of the enzymes. In supplementary experiments using both specific antiserum and PCR primers it was shown that HGEC express message and secrete both the specific metalloproteinase inhibitors TIMP-I and TIMP-II. These results indicate that the synthesis and secretion of degradative enzymes and their controlling inhibitors by HGEC have the potential to be involved in the turnover of the extracellular matrix.

Base Sequence↗
PubMed1995

Rat mesangial cells in vitro synthesize a spectrum of proteoglycan species including those of the basement membrane and interstitium.

Accumulation of extracellular matrix within the mesangium is an important event in the development of glomerular disease. In this report we have used indirect immunofluorescence to positively identify a number of constituents of the mesangial matrix synthesized by rat mesangial cells (RMC) in vitro including laminin, fibronectin, type IV collagen and the basement membrane heparan sulphate proteoglycan (BM-HSPG) known as perlecan. In addition, using Mab 2B5 we demonstrate that RMC synthesize a specific basement membrane chondroitin sulfate (BM-CSPG), a matrix component that in normal animals is localized in the mesangium but is not found in the pericapillary glomerular basement membrane (GBM). Further characterization of the proteoglycans synthesized by RMC in vitro revealed: (i) a second large CSPG, identified as versican; (ii) two small dermatan sulphate proteoglycans identified as biglycan and decorin, which together account for the majority of the proteoglycans; (iii) a large HSPG-I, probably related to perlecan; and (iv) a small HSPG-II. The cell layer proteoglycans can be sub-divided into a class that are probably free in the membrane, and a class of anchored molecules of the extracellular matrix or stabilized by cytoskeletal elements.

Animals↗
PubMed1995

Applying contextual interference to the Pawlata roll.

Contextual interference is manipulated by changing the practice order of a number of similar motor tasks, so that the learning context of each interferes with that of the other. The effect has been found to generalize to baseball batting, badminton serving and volleyball skills. The present study examined whether this practice technique could be applied to a Pawlata roll in a kayak. The study was further motivated by the fact that many instructors in Britain currently advocate learning the Pawlata roll in one direction only to a criterion of accuracy, thereafter transferring to the opposite direction. Contextual interference literature predicts that skill retention would be better served by practising on alternate sides. Accordingly, 16 undergraduate students with no kayaking experience were randomly allocated to either a low contextual interference group, which followed U'ren's (1993) recommendations, or a high contextual interference group, which practised the skill on alternate sides. The high contextual interference group took less time to acquire the skill, and were also quicker to achieve successful performance in retention (full roll) and transfer (half roll) tests, regardless of the direction of the roll, 1 week later. The time savings in practice were not expected, as acquisition under high contextual interference was improved rather than impaired. This finding suggests that bilateral transfer was increased by randomizing practice. These results are worthy of further investigation, in that they suggest that the recommended training methods may not be optimal.

Adolescent↗
PubMed1995

Expression of the rat, S-100-related, calcium-binding protein gene, p9Ka, in transgenic mice demonstrates different patterns of expression between these two species.

p9Ka (also known as mts1/18A2/calvasculin/CAPL) is a member of the S-100-related family of small, calcium-binding proteins. Previous studies suggest apparent discrepancies between the expression of the p9Ka gene in rat, mouse, and human tissues. Here we demonstrate that the natural p9Ka gene is expressed at lower levels in mouse than in rat, and that, in mouse but not in rat, p9Ka mRNA is more highly expressed in cells of lymphoid origin. Transgenic mouse strains express rat-p9Ka transgenes in a gene copy-number-dependent manner. The rat p9Ka transgene mRNA shows the same tissue distribution in several lines of transgenic mice, a distribution that is characteristic of the rat, from which the transgenes were derived. These results show that there is a difference in the pattern of expression of the same gene in two closely related species, and that the pattern of expression found in rat is specified by the DNA in the rat gene itself.

Amino Acid Sequence↗
PubMed1995

Vitamin D intoxication causes hypercalcaemia by increased bone resorption which responds to pamidronate.

OBJECTIVE: Vitamin D intoxication is a relatively rare but treatable cause of hypercalcaemia. In the past this has been undertaken using corticosteroids. Previous observations have suggested that there is increased bone resorption in hypervitaminosis D. If this were to be the case, specific inhibitors of bone resorption might provide more effective treatment. We have therefore studied the mechanisms of hypercalcaemia and response to therapy in a group of patients with vitamin D intoxication. DESIGN: Vitamin D metabolites were measured in six patients with vitamin D intoxication; in five of these the components of hypercalcaemia were calculated. These measurements were repeated following treatment with corticosteroids (two patients) or the bisphosphonate, pamidronate (three patients). RESULTS: In each case the serum 25-hydroxyvitamin D was grossly elevated and there was a more modest elevation in serum 1,25-dihydroxyvitamin D. The components of hypercalcaemia suggest that there was a significant degree of bone resorption in all six patients and that this is the major determinant of hypercalcaemia. Pamidronate treatment resulted in a brisk reduction in plasma calcium concentration. Following corticosteroids the return of calcium to normal was more delayed. CONCLUSION: The hypercalcaemia of vitamin D intoxication is mediated by increased bone resorption and bisphosphonates have a role in its management.

Adrenal Cortex Hormones↗
PubMed1995

Seasonal rhythm of platelet [3H]imipramine binding in adolescents who attempted suicide.

OBJECTIVE: This study was designed to determine the seasonality of serotonin functions among adolescents who attempt suicide. METHOD: Platelet [3H]imipramine binding was assessed over a period of 18 months in 98 adolescents who attempted suicide and a comparison group of 23 never-suicidal youths with conduct disorder. RESULTS: [3H]Imipramine (Bmax) was uncorrelated with age, but showed considerable seasonal variability over time in those who had attempted suicide. CONCLUSIONS: [3H]Imipramine binding density in adolescents who attempted suicide exhibited significant seasonality, reaching a nadir in late winter/early spring.

Adolescent↗
PubMed1995

How fish power predation fast-starts

Short-horned sculpin (Myoxocephalus scorpius L.) were acclimated for 6­8 weeks to either 5 °C or 15 °C (12 h dark: 12 h light). Fast-starts elicited by prey capture were filmed from above in silhouette using a high-speed video camera (200 frames s-1). Outlines of the body in successive frames were digitised and changes in strain for the dorsal fast muscle calculated from a knowledge of backbone curvature and the geometrical arrangement of fibres. For 15 °C-acclimated fish at 15 °C, muscle strain amplitude (peak-to-peak) during the first tail-beat was approximately 0.16 at 0.32L, 0.19 at 0.52L and 0.15 at 0.77L, where L is the total length of the fish. Fast muscle fibres were isolated and subjected to the strains calculated for the first tail-beat of the fast-start (abstracted cycle). Preparations were electrically stimulated at various times after the initiation of the fast-start using an in vivo value of duty cycle (27 %). Prior to shortening, muscle fibres at 0.52L and 0.77L were subjected to a pre-stretch of 0.055l0 and 0.085l0 respectively (where l0 is resting muscle length). The net work per cycle was calculated from plots of fibre length and tensile stress. For realistic values of stimulus onset, the average power output per abstracted cycle was similar at different points along the body and was in the range 24­31 W kg-1 wet muscle mass. During shortening, the instantaneous power output reached 175­265 W kg-1 wet muscle mass in middle and caudal myotomes. At the most posterior position examined, the muscle fibres produced significant tensile stresses whilst being stretched, resulting in an initially negative power output. The fibres half-way down the trunk produced their maximum power at around the same time that caudal muscle fibres generated significant tensile stress. Fast muscle fibres at 0.37­0.66L produced 76 % of the total work done during the first tail-beat compared with only 14 % for fibres at 0.67­0.86L, largely reflecting differences in muscle mass. The effect of temperature acclimation on muscle power was determined using the strain fluctuations calculated for 0.52L. For 5 °C-acclimated fish, the average power per cycle (± s.e.m.; W kg-1 wet muscle mass) was 21.8±3.4 at 5 °C, falling to 6.3±1.8 at 15 °C. Following acclimation to 15 °C, average power per cycle increased to 23.8±2.8 W kg-1 wet muscle mass at 15 °C. The results indicate near-perfect compensation of muscle performance with temperature acclimation.

Journal Article↗
PubMed1995

Patients with multiple sclerosis presenting to psychiatric hospitals.

BACKGROUND: Although many neuropsychiatric syndromes are associated with multiple sclerosis, few recent studies have examined the clinical features of psychiatric illness in inpatients with multiple sclerosis. Florid psychopathology can obscure neurologic symptoms in multiple sclerosis. It is therefore important to consider the range of severe psychiatric states that can occur in multiple sclerosis and the frequency with which multiple sclerosis patients are seen in inpatient facilities. METHOD: We examined records for 2720 consecutive admissions to three psychiatric units and conducted a chart review comparing the DSM-III psychiatric diagnoses of patients with multiple sclerosis with those of the inpatient population as a whole. RESULTS: The 10 patients with multiple sclerosis were significantly more likely to present with histories of mania and manic psychosis than the inpatient population as a whole. Further, 7 of the 10 patients had psychiatric hospitalizations before the multiple sclerosis diagnosis. In 4 of these 7 patients, a review of the medical record documented neurologic symptoms that were not recognized as typical of multiple sclerosis. Three of these 4 patients were psychotic and the fourth was catatonic at the time of their admissions. CONCLUSION: While multiple sclerosis patients account for a small proportion of all psychiatric admissions, clinicians should consider the diagnosis of multiple sclerosis in patients exhibiting manic symptoms in tandem with unexplained neurologic findings.

Adult↗
PubMed1995

Source of peritoneal proteoglycans. Human peritoneal mesothelial cells synthesize and secrete mainly small dermatan sulfate proteoglycans.

This study describes experiments that compare the proteoglycans (PGs) extracted from the dialysate from patients receiving continuous peritoneal ambulatory dialysis (CAPD) with those secreted by metabolically labeled human peritoneal mesothelial cells in vitro. The PGs isolated from both sources were predominantly small chondroitin sulfate/dermatan sulfate PGs. Western blot of the core proteins obtained after chondroitin ABC lyase treatment with specific antibodies identified decorin and biglycan. With [35S]sulfate and [35S]methionine as labeling precursors it was shown that dermatan sulfate rather than chondroitin sulfate were the major glycosaminoglycan chains and that decorin was the predominant species. These data provide the first evidence that human peritoneal mesothelial cells may be the principal source of PGs in the peritoneum. Given the proposed functions of decorin and biglycan, the results suggest that these PGs may be involved in the control of transforming growth factor-beta activity and collagen fibril formation in the peritoneum.

Ascitic Fluid↗
PubMed1995

Computerized support of pressure ulcer prevention and treatment protocols.

Pressure ulcer prevention and treatment protocols were developed and implemented at LDS Hospital. While the protocols were initially implemented "on paper", compliance was not optimum until the hospital's information system was modified to support the clinician in following the new protocols. Preliminary results indicate a significant reduction in the incidence of pressure ulcers.

Clinical Protocols↗
PubMed1995

Monitoring the uptake of Hib vaccine in Forth Valley.

Haemophilus influenzae type b (Hib) infection is an important cause of morbidity and mortality among young children in this country. Immunisation against the disease using protein conjugate Hib vaccine was introduced in the United Kingdom on 1 October 1992. To monitor the impact of this new vaccine in the routine childhood immunisation schedule in Forth Valley Health Board area, a survey of the parents of 200 children born during August 1992 was carried out. A total of 163 (82%) parents responded. While most parents had heard of Hib vaccine or of diseases caused by Hib, specific gaps in their knowledge were noted. In particular a substantial minority (31%) were not aware of the role of Hib vaccine in preventing meningitis. Among health professionals who advised parents on immunisation, the most important group identified by parents were health visitors, followed by family doctors. Leaflets produced by the Health Education Board for Scotland also formed an important and valuable source of information for parents, as did television, radio and newspapers. Monitoring the uptake of Hib vaccine in the sample of 200 children revealed a high uptake of the three recommended doses (96%), with only one child receiving no immunisations at all. If this level of uptake is achieved in other areas then the full potential of the new Hib vaccine in preventing infection among young children will be considerable.

Child, Preschool↗