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Biomedical subjects

M Slater

Publications and source records attributed to M Slater.

At least 19 recordsLinked to original sources
PubMed1995

Thrombospondin co-localises with TGF beta and IGF-I in the extracellular matrix of human osteoblast-like cells and is modulated by 17 beta estradiol.

Thrombospondin (TSP) is a multifunctional glycoprotein which is synthesised by several cell types including osteoblasts, and incorporated into the extracellular matrix (ECM) of these cells. The function and regulation of TSP in bone is not clear. In this study, using a long term culture model of human osteoblast-like cells, we examined the distribution of TSP in the ECM and its modulation by added estradiol. In this model the osteoblast-like cells form a regular multilayer which continues to increase in depth up to 50 days post confluence. In the ECM of these cultures and in 19-week fetal bone, the bone markers osteocalcin and alkaline phosphatase were diffusely distributed in the matrix. In contrast, labelling for TSP was concentrated, confined to the banded collagen and its immediately adjacent ECM. This pattern of labelling resembled that of the growth factors transforming growth factor beta-I (TGF beta), and insulin-like growth factor-I (IGF-I), with which TSP label co-localised. Labelling intensities were comparable between fetal bone and the in vitro material for TSP, TGF beta and IGF-I. TSP label was present by 10 days post confluence, reached a maximum by 20 days, and declined slowly thereafter, a time course which was similar to that of IGF-I. Incubation of osteoblast-like cell cultures with 17 beta estradiol resulted in an increase in multilayer depth and a maximal 3-fold increase in TSP labeling at 30 days as well as approximately 2-fold increases for TGF beta and IGF-I. The dose-response relationship for these responses to estradiol treatment was biphasic with maximal increases at 10(-10) M-10(-11) M of added estradiol. Treatment with 17 alpha estradiol produced labelling intensities that were not significantly different from controls. Studies with other cell types have suggested that TSP may be involved in modulation of growth factor activity. The similarities between TSP, TGF beta and IGF-I, in terms of their distribution and regulation by 17 beta estradiol treatment, may indicate a role for TSP in modulating bone cell proliferation and function through interaction with local growth factors.

Alkaline Phosphatase↗
PubMed1995

Involvement of platelets in stimulating osteogenic activity.

Osteoblast-like cells have been shown to be sensitive to the proliferative action of a wide variety of growth factors. Many of these growth factors have been isolated from platelets and are thought to be released at local sites in response to injury. In this study, we tested whether human platelet concentrate, as a supplement to basic medium, would support the proliferative and functional activity of human fetal osteoblast-like cells in both short-term and long-term culture. In short-term studies, uptake of [3H]thymidine was increased in platelet-treated cultures by more than 4-fold compared with 10% serum-supplemented controls. When cultured for prolonged periods on coverslips, the cells formed multilayers, with a collagen-based matrix separating the layers. Long-term cultures that were treated with 1.5% (vol/vol) platelets in serum-supplemented medium showed increases in the depth of the multilayers of as much as 36-fold at 30 days after confluence, compared with the 10% serum-supplemented controls; this difference persisted until day 50. Incorporation of growth factor in the matrix was examined with the use of colloidal gold immunoelectron microscopy. Immunogold labeling intensities for transforming growth factor-beta 1 were significantly lower in the platelet-treated cultures at 20 days and then increased to a maximum level of 2.1-fold more than in the controls at 40 days. Labeling intensities for insulin-like growth factor-I and basic fibroblast growth factor were significantly lower in the platelet-treated cultures than in the controls at all stages of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1994

Role of chondroitin sulfate glycosaminoglycans in mineralizing osteoblast-like cells: effects of hormonal manipulation.

A monoclonal anti-chondroitin sulfate antibody (CS-56) that recognizes native chondroitin sulfate glycosaminoglycans (CSGAG) was used to quantify changes in CSGAG labeling levels in mineralizing human fetal osteoblast-like cell multilayers up to 40 days postconfluence. In control cultures, mean labeling of CSGAG increased in nonmineralized areas from around eight gold probes per micron 2 (gpm) at 20 days to 26 gpm at 40 days. Labeling was markedly increased in the mineralized tissue, to 560 gpm at 30 days and 580 gpm at 40 days. In beta-glycerophosphate-treated cultures, the mineralized areas were increased and appeared earlier (20 days) than in the control cultures. In these cultures, mean CSGASG labeling increased in nonmineralized areas from around 5 gpm at 20 days to 26 gpm at 30 days and was further increased in mineralized areas to 270 gpm at 20 days and 298 gpm at 30 days. Mineralization was not noted in cultures treated with 10(-8) M 1,25-dihydroxyvitamin D, and CSGAG labeling remained low (< 5 gpm) during the study period. These results indicate that an increase in immunoreactive CSGAG is associated with mineralization in this culture system. One possible interpretation of these findings is that proteoglycan molecules or at least their CSGAG side chains may be involved in the mineralization process.

Antibodies, Monoclonal↗
PubMed1994

Immunogold localization of TGF beta 1 protein and mRNA in human skin using a colloidal gold/digoxygenin system.

Tissue preservation, and immunogold cytochemical and in-situ hybridization labelling intensities vary according to the preparatory protocols used. We wished to determine which preparative protocols produce optimal preservation, protein and mRNA labelling. Nine combinations of fixative and embedding resin were therefore studied using postembedding immunoelectron microscopy and a novel immunogold digoxygenin in situ hybridization (ISH) system, to quantitate the presence of transforming growth factor beta 1 (TGF beta 1) protein and message in human skin. The best preservation was observed in tissue fixed in 1% glutaraldehyde and embedded in LR White resin or low acid glycolmethacrylate resin (LA-GMA). Preservation was poor in tissue fixed with 1% glutaraldehyde and fair in 4% paraformaldeyde, when embedded in Unicryl. Ethanediol dehydration coupled with LA-GMA embedding resulted in reasonable preservation. Based on quantitative measures of the labelling density for TGF beta 1 protein and mRNA, immunogold labelling was adequate with 1% glutaraldehyde fixation coupled with LR White or LA-GMA resins, and also with 4% paraformaldehyde and LR White resin, but was best with ethanediol dehydration and LA-GMA embedding. ISH labelling under basal conditions was best in LA-GMA with 1% glutaraldehyde or 4% paraformaldehyde. The ISH label in tissue fixed with 1% glutaraldehyde and embedded in LA-GMA was significantly increased by treatment with proteinase K. Overall, ethanediol dehydration was associated with a good immunoelectron microscopic (IEM) label while LA-GMA with 1% glutaraldehyde or 4% paraformaldehyde resulted in a consistently detectable ISH label. LA-GMA embedding with 1% glutaraldehyde fixation gave a good result with both IEM and ISH labelling.

Digoxigenin↗
PubMed1994

Modulation of growth factor incorporation into ECM of human osteoblast-like cells in vitro by 17 beta-estradiol.

Human fetal osteoblast-like cells formed a regular multilayered structure in vitro with an extensive collagen-based extracellular matrix. With colloidal gold immunocytochemistry, labels for alkaline phosphatase and osteocalcin were distributed in a relatively diffuse pattern, in contrast to the bone growth factors, insulin-like growth factors I and II (IGF-I and IGF-II), transforming growth factor-beta 1 (TGF-beta 1), and basic fibroblast growth factor, which were colocalized in the collagenous matrix of the multilayer. The inclusion of 17 beta-estradiol (10(-11) to 10(-9) M) in the culture medium increased multilayer depths, increased labeling for IGF-I, IGF-II, and TGF-beta 1, and resulted in earlier detection of TGF-beta 1 label. In contrast, the increase in multilayer depth resulting from treatment with human platelets, an exogenous source of growth factors, was not accompanied by an increase in matrix IGF-I, IGF-II, or TGF-beta 1 label, suggesting a particular effect of estradiol to facilitate this process. Because growth factors in bone matrix may act as coupling agents when released during resorption, reduced growth factor incorporation in the presence of reduced sex steroid concentrations may lead to uncoupling of resorption and subsequent formation.

Alkaline Phosphatase↗
PubMed1994

The determination of comparable labeling densities in quantitative immunoelectron microscopic double labeling studies.

In quantitative ultrastructural studies using colloidal gold immunocytochemical techniques, labeling intensities vary according to the size of the probe used. Using postembedded indirect two-sided double labeling and single labeling protocols, the labeling characteristics of four antigens were studied using two probe sizes commonly used in double labeling studies. It was determined that the labeling intensity variation resulting from the use of different probe sizes was unpredictable after correcting for the increased probe size alone. It was possible, however, to obtain comparable labeling densities by first determining the labeling intensities for each probe size with its antigen in single label studies on serial sections and using the same procedure as the double labeling studies. A probe size correction factor for each antigen was calculated from these data. This factor was used to obtain comparable measurements of the relative abundance of each label.

Antibodies↗
PubMed1994

Dental health of 14-year-old children in St. Ouen, France and Salford, England.

Fourteen-year-old children in two schools, 82 in St Ouen, France and 133 in Salford, England were examined to compare their dental health. The mean DMFT in St Ouen was 4.83 and in Salford 5.49. This difference was not significant. However, St Ouen children had significantly fewer fillings with a mean of 1.16 compared with 1.95 in Salford (P < 0.05). Eighty-two per cent of the Salford children said that they had visited the dentist in the past year compared with 54 per cent of the St Ouen children (P < 0.001). Significantly more Salford children considered that regular visits to the dentist were very/fairly important for preventing dental caries and periodontal disease.

Adolescent↗
PubMed1994

Comparison of species and numbers of bacteria in concurrently cultured samples of proximal small intestinal fluid and endoscopically obtained duodenal mucosa in dogs with intestinal bacterial overgrowth.

Concurrent bacterial culturing of duodenal/proximal jejunal fluid and duodenal mucosa was performed on 2 occasions in each of 16 IgA-deficient German Shepherd Dogs with small intestinal bacterial overgrowth. The interval between sample collections in each dog was 74 to 78 days. Species of bacteria and numbers of bacterial colony-forming units (CFU) per milliliter of fluid were compared with species and numbers found in the concurrent duodenal mucosa sample. There was inconsistent correlation for number of CFU and minimal correlation for species of bacteria isolated from the 2 sites. Fewer bacterial CFU usually were isolated from the mucosa than from the concurrent fluid sample. When the same numeric criteria used for diagnosing small intestinal bacterial overgrowth in samples of intestinal fluid (ie, > or = 10(5) bacterial or > or = 10(4) anaerobic CFU/ml) were used to interpret results of culturing duodenal mucosa, quantitations of bacterial CFU in duodenal mucosa was found to be a specific, but insensitive test.

Animals↗
PubMed1992

French Dental Association Conference.

Paris was invaded twice by dentists during November 1991! On November 17, dentists were at the head of 400,000 health professionals demonstrating against Government proposals for changes in the health system. They feel that changes would result in loss of freedom of choice for the patient, and would threaten the autonomy of the independent health professions. Many of the same dentists returned to the capital on November 27, for the most important dental continuing education meeting of the year, the twentieth ADF Conference.

Computers↗
PubMed1991

Plurihormonality in the secretory granules of the normal human pituitary. An immunoelectron microscopic study.

Normal human autopsy anterior pituitary tissue from 5 cases was embedded in LR White resin and immunolabelled using silver-enhanced 5-nm protein A gold probes. Follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), adrenocorticotrophic hormone (ACTH), growth hormone (GH) and prolactin (PRL) were immunolocalised to the level of secretory granule. A two-sided double-labelling method was used to cross-react two hormones at a time with respect to their corresponding antibodies. All possible combinations of the six pituitary hormones were tested. Plurihormonal granules were found that contained LH + FSH, LH + TSH, and FSH + TSH. Each hormone was also found in monohormonal granules. Granule diameter was significantly larger in the pluri as opposed to monohormonal granules.

Aged↗
PubMed1991

A program to prepare minority students for careers in medicine, science, and other high-level professions.

The Gateway to Higher Education program is a comprehensive four-year high school program with specially designed enrichments and supports. Its principal goal is to increase the number of minority students who will be prepared to enter training for high-level professional careers, especially in medicine and science. The program was established in September 1986 to demonstrate that minority students who perform at least at grade level can begin a rigorous curriculum in the ninth grade and achieve outstanding results, provided that the necessary support systems are in place. For 1990-91, 750 students are enrolled in Gateway programs at five New York City public high schools, and the first 119 students graduated in June 1990. The graduates have demonstrated significant achievement compared with that of their peers, as measured by standardized tests and the graduates' participation in research mentorships and college acceptances. In order to expand on its initial success, the program has increased its scope of activity to include over 400 students at the junior high school level.

Achievement↗
PubMed1991

Immunoelectron microscopic localization of fibronectin and complement to 'dense bodies' in Bowman's capsule and the glomerular basement membrane in membranous nephropathy.

This study describes dense bodies seen in Bowman's capsule and the glomerular basement membrane in biopsies of membranous glomerulonephritis. Within these bodies, silver-enhanced immunogold labelling demonstrated the presence of fibronectin and the complement component C3b. These results suggests that dense bodies may play a role in opsonization and the immune process in membranous glomerulonephritis.

Basement Membrane↗
PubMed1991

A method for the examination of the same cell using light, scanning and transmission electron microscopy.

A method is described for preparing the same cell from a cytospin preparation for comparative investigation by light microscopy, scanning electron microscopy and transmission electron microscopy. A permanent numbered grid pattern was etched on a glass microscope slide to facilitate cell location in each microscopic mode. Data from one cell or group of cells was thus obtained from three sources. This method provides a useful adjunct to routine cytological diagnosis.

Cells↗
PubMed1991

Differential silver enhanced double labeling in immunoelectron microscopy.

A two-sided double labeling method using protein A gold was used to demonstrate the presence of two hormones within the same anterior pituitary cell granule. A single probe size was used for both section faces but one side of the grid was silver enhanced. The use of a single probe size reduced the cost of the study and eliminated the variations in labeling efficiency that result from the use of different probe sizes.

Follicle Stimulating Hormone↗