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Biomedical subjects

S B Smith

Publications and source records attributed to S B Smith.

At least 109 records · Page 6Linked to original sources
PubMed1995

Restraints: retraumatization for rape victims?

Clients who have experienced trauma through rape or sexual assault discuss the traumatic feelings associated with being placed in leather restraints during times of hospitalization for psychiatric/mental health problems. In the eyes of those who have openly discussed their private interpretations of their experiences, restraint becomes revictimization. The clients who came forward to tell their stories may be only a small percentage, or they may represent a much larger percentage of the inpatient psychiatric population than nurses and therapists have recognized. Developing a therapeutic rapport with clients is a critical element of psychiatric/mental health nursing that may be severely impaired if the client perceives nurses to be perpetrators of violence.

Adult↗
PubMed1995

Photoreceptor cells in the vitiligo mouse die by apoptosis. TRPM-2/clusterin expression is increased in the neural retina and in the retinal pigment epithelium.

PURPOSE: To determine the mechanism of photoreceptor cell death in the vitiligo mouse, a model of retinal degeneration in which the genetic defect is not retina specific but is instead caused by single point mutation in the microphthalmia (mi) gene that codes for a basic helix-loop-helix DNA transcription factor. METHODS: Detection of apoptotic cells was performed in fixed retinal tissue using the TUNEL assay in animals 1, 2, 4, 6, 8, 16, 32, 40, and 52 weeks. Electron microscopic analysis was used to confirm the morphologic hallmarks of apoptosis, and Southern blot analysis was used to detect internucleosomal DNA fragmentation. Additionally, the expression of a gene associated with apoptosis, TRPM-2/clusterin, was examined. RESULTS: At ages beyond the time of normal retinal programmed cell death, vitiligo retinas had significantly more TUNEL-positive photoreceptor cells and more photoreceptor cells with condensed chromatin than controls. DNA internucleosomal fragmentation ladders were present in vitiligo retinas even as late as 15 weeks, a time well beyond developmental apoptosis in controls. TRPM-2/clusterin mRNA levels in vitiligo neural retinas were similar to controls initially but were two times greater than controls by 12 weeks. Surprisingly, TRPM-2/clusterin mRNA levels were elevated in the retinal pigment epithelium in the mutant; the expression at one week was two times greater than normals and remained elevated for many months, even though retinal pigment epithelial cells showed no morphologic evidence of apoptosis. CONCLUSIONS: The morphologic and biochemical data suggest that photoreceptor cells die by apoptosis in vitiligo mice. The increased retinal TRPM-2/clusterin mRNA levels may be a direct response to these events. The increased expression of this gene in the retinal pigment epithelium, however, may reflect its role in tissue regression and membrane remodeling. Mechanisms by which the mi gene defect might result in the vitiligo retinopathy are proposed.

Aging↗
PubMed1994

Increase in retinyl palmitate concentration in eyes and livers and the concentration of interphotoreceptor retinoid-binding protein in eyes of vitiligo mutant mice.

Retinyl esters play an important role in the visual cycle because they are involved in regeneration of 11-cis-retinal for use in rhodopsin formation. In the present study, retinyl ester concentrations were significantly elevated in eyes and livers of mice homozygous for the vitiligo mutation (mivit/mivit). Vitiligo mice demonstrate a slowly progressing retinal degeneration characterized by gradual loss of photoreceptor cells and rhodopsin as well as uneven pigmentation of the retinal pigment epithelium (RPE). Analysis of retinoids by h.p.l.c. indicated that the retinyl palmitate level was increased fivefold in eyes of affected mice at 10 weeks postnatally and was threefold higher at 22 weeks of age. Accumulation of retinyl palmitate occurred in the RPE rather than the neural retina. Furthermore, the concentration of all-trans-retinol was elevated in the RPE of vitiligo mice. Levels of interphotoreceptor retinoid binding protein (IRBP) were increased in vitiligo mice between ages 4 and 14 weeks, but returned to normal by 16 weeks. Increased IRBP levels were not due to increased protein synthesis because IRBP mRNA levels did not differ significantly between control and affected animals. To examine possible systemic involvement in vitiligo mice, retinoids were evaluated in liver and plasma. Mean hepatic total vitamin A levels in affected mice were approximately 1.7 times higher than controls. Analysis of esterified and non-esterified retinoids in liver showed that the concentration of retinyl palmitate was elevated. Plasma retinol levels were normal. This study provides the first evidence of altered systemic retinoid metabolism in vitiligo mice, which occurs, significantly, under normal dietary conditions.

Animals↗
PubMed1994

Effects of dark-rearing on the retinal degeneration of the C57BL/6-mivit/mivit mouse.

The C57BL/6J-mivit/mivit mouse has a retinal degeneration in which photoreceptor cells are lost slowly at a rate of about one row per month beginning at 8 weeks. ROS are severely disrupted by 4 months, but inner segments maintain a normal length through 6 months. In addition to photoreceptor changes, the retinal pigment epithelium is unevenly pigmented. The present study utilized histological and biochemical techniques to assess the effects of dark-rearing on the progression of the retinal degeneration in the mivit/mivit mouse at ages 4, 6, 8, 12, 16, 20, 24, and 28 weeks. Results of systematic morphometric evaluation indicated that the rate of loss of photoreceptor cells did not differ significantly from the rate determined for mivit/mivit animals reared in a standard light cycle. Furthermore, retinal detachment from RPE, the displacement of darkly-staining cells into the subretinal space and the influx of macrophage-like cells in the area of the ROS were still present in mivit/mivit animals reared in darkness. ROS of mivit/mivit seemed to be preserved for a slightly longer period of time in the dark-rearing condition. Rhodopsin levels in 4-week dark-reared mivit/mivit mice were 0.32 +/- 0.04 nmol per retina which was comparable to mivit/mivit mice reared under standard lighting conditions. At 20 and 28 weeks, rhodopsin levels decreased in mivit/mivit retinas to a similar level regardless of their lighting history. The findings of the study suggest that light deprivation does not retard the degeneration mivit/mivit retina. Results are discussed in comparison with effects of dark-rearing on other models of retinal degeneration.

Animals↗
PubMed1994

Stearoyl coenzyme A desaturase enzyme activity and mRNA levels are not different in subcutaneous adipose tissue from Angus and American Wagyu steers.

We proposed that greater stearoyl coenzyme A (CoA) desaturase enzyme activity caused the elevated monounsaturated fatty acids observed in American Wagyu adipose tissue. Stearoyl CoA desaturase mRNA concentrations and enzyme activities were measured in subcutaneous adipose samples from Angus (n = 5) and American Wagyu (n = 5), fed to the Japanese market end point. A rat liver stearoyl CoA desaturase cDNA clone was used to measure the relative amounts of stearoyl CoA desaturase mRNA. Enzyme activities and mRNA concentrations, as measured by laser densitometry of slot-blot autoradiograms, were not significantly different between the two breeds at this stage of growth. This investigation has demonstrated that, at this stage of maturity, differences in fatty acid composition between Angus and American Wagyu steers cannot be attributed to differences in stearoyl CoA desaturase enzyme activity.

Adipose Tissue↗
PubMed1994

Evidence for preadipocyte proliferation during culture of subcutaneous and intramuscular adipose tissues from Angus and Wagyu crossbred steers.

The primary objective of this study was to provide evidence for preadipocyte proliferation during culture of adipose tissue explants; a secondary objective was to compare the lipogenic activity and cellularity of adipose tissues from American Wagyu crossbred steers. Subcutaneous (s.c.) and intramuscular (i.m.) adipose tissues were obtained at slaughter from the 2nd to 6th lumbar region of the loin from Angus (n = 10) and Wagyu crossbred steers (n = 10) that had been fed for 552 d by typical Japanese production standards. Adipose tissue explants were incubated 36 h with [3H]thymidine in the absence and presence of aphidicolin (a specific inhibitor of genomic DNA replication). Adipocytes were liberated by collagenase treatment and [3H]thymidine incorporation into DNA was measured. Whereas there were no significant differences between adipose tissue depots, Wagyu s.c. and i.m. preadipocytes and stromal-vascular cells exhibited greater (P < .05) [3H]thymidine incorporation into DNA than adipocytes from Angus steers. Intramuscular adipose tissue from both breeds exhibited lower (P < .05) rates of lipogenesis from acetate both before and after long-term (36-h) incubation than s.c. adipose tissue. Furthermore, i.m. adipocytes were smaller (P < .05) than s.c. adipocytes. The activities of fatty acid synthetase and glucose-6-phosphate dehydrogenase were greater (P < .05) in Wagyu s.c. adipose tissue and less in Wagyu i.m. adipose tissue than in corresponding Angus tissues. There were no differences between breed types (P = .17) in rates of lipogenesis from acetate, either before or after explant culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipocytes↗
PubMed1994

Simple bone cyst of the calcaneus. A case report and literature review.

The authors presented a case report of a patient presenting with heel pain symptoms and physical findings similar to those associated with a heel spur syndrome. With a standard x-ray, the presence of a simple bone cyst was evident. Although mainly reported in tubular bones, steroid injection therapy has been successful and appears to be replacing surgical curettage and packing as the preferred choice of treatment in many cases. As more reports of the successful eradication of simple bone cysts of the calcaneus with steroid injections are reported, greater confidence for using it as a treatment choice for this particular lesion may be gained. The surgical approach in the patient presented here was chosen because of factors that the authors believe increased the likelihood of a pathologic fracture, such as size and extent of the lesion, history of progressive pain, and activity level of the patient. The larger body weight and the resulting stress of the patient more likely to present with a calcaneal cyst may also be factors to consider.

Adult↗
PubMed1994

Reduction of phagosomes in the vitiligo (C57BL/6-mivit/mivit) mouse model of retinal degeneration.

PURPOSE: The vitiligo (C57BL/6-mivit/mivit) mouse has a slowly progressing retinal degeneration, in which photoreceptor cell nuclei are gradually lost and the retinal pigment epithelium (RPE) is unevenly pigmented. The purpose of the present study was to assess the phagocytic ability of the RPE in the vitiligo mouse by determining whether and when a phagocytic burst occurs in affected mice and whether the number of phagosomes varies between control and affected animals. METHODS: Eyes of control and vitiligo mice 4 to 20 weeks of age were embedded in Spurr. Thin sections were cut and examined by electron microscopy to confirm the presence of phagosomes, particularly in the affected animals. Thick (1 micron) sections were cut, and quantitative morphometry was performed at the light microscope level. The length of RPE was determined, and phagosomes were counted in RPE cytoplasmic and microvillous areas. Data were expressed as phagosomes per 1000 microns. RESULTS: The vitiligo mouse has a peak phagocytic episode approximately 2 hours after light onset. The number of phagosomes in 4-week-old affected mice was significantly less than that in controls (13 phagosomes per 1000 microns compared to 30 phagosomes per 1000 microns). By week 8, the number was reduced to approximately 5 per 1000 microns. Phagosome number was not reduced further between weeks 8 and 20 in the affected animal. Macrophage-like cells containing pigment granules and phagosomes were observed in the subretinal space in areas where the rod outer segments had been separated from the RPE. CONCLUSIONS: The vitiligo mouse RPE contains phagosomes, but there are significantly fewer than in controls. It is not known whether a defect in RPE phagocytosis is the direct cause of the retinal defect in this model.

Animals↗
PubMed1994

Electroretinographic study of the C57BL/6-mivit/mivit mouse model of retinal degeneration.

PURPOSE: The C57BL/6-mivit/mivit mouse model of retinal degeneration is characterized by slow progressive loss of photoreceptor cells, concomitant loss of rhodopsin, and uneven pigmentation of the retinal pigment epithelium. The purpose of this study was to determine how these alterations affected the electroretinogram (ERG). METHODS: Scotopic ERGs were measured in two litters of mivit/mivit mice beginning at 4 weeks and continued in the same animals at 2-week intervals through 18 weeks. RESULTS: The mean of the maximum b-wave amplitude (Vmax) at 4 weeks was 234 +/- 14 microV in mivit/mivit mice, which did not differ significantly from controls (266 +/- 26 microV). With increasing age, all components of the ERG decreased and by 12 weeks, the mean of the Vmax had decreased to 170 microV. At 18 weeks, the mean Vmax was 75 microV, and the b- to a-wave ratio was still > 1.0. Comparison of these physiologic data to previously reported morphologic and biochemical data showed a high correlation between the b-wave amplitude and the number of photoreceptor cell nuclei (r = 0.9772) as well as the b-wave amplitude and rhodopsin levels (r = 0.9019). CONCLUSIONS: The loss of all components of the ERG and the lack of a negative-type ERG suggested that the primary cells altered in the mivit/mivit mouse were the photoreceptors. The high correlations between the ERG amplitude and the number of photoreceptor nuclei indicate that the Vmax of the ERG is a good measure of the degree of photoreceptor loss.

Animals↗
PubMed1993

Towards a molecular description of pulsed-field gel electrophoresis.

An improved understanding of the molecular processes of migration and reorientation of DNA molecules undergoing conventional and pulsed-field gel electrophoresis (PFGE) should provide the basis for the rational optimization of these techniques. This review of common pulsed-field methods emphasizes the range of their applications as well as their current limitations. The molecular mechanisms involved in electrophoresis, as they are beginning to emerge from a combination of direct observations using a microscope and computer-modeling studies, are also discussed.

Computer Simulation↗
PubMed1993

Fatty acid-binding protein in bovine longissimus dorsi muscle.

Experiments were conducted to purify and obtain amino acid sequence data for fatty acid-binding protein from bovine longissimus dorsi muscle. 1. Separation of sarcoplasmic proteins by fractionation on Sephadex and DEAE cellulose columns indicated that a low abundance fatty acid-binding protein exists in bovine l. dorsi muscle. 2. Fatty acid-binding protein in bovine l. dorsi muscle cannot be separated from myoglobin by standard protein purification procedures. However, partial sequencing of a partially purified protein fraction indicated the presence of an NH2-terminally blocked protein. 3. Myoglobin bound palmitate under the in vitro conditions of these experiments.

Amino Acid Sequence↗
PubMed1993

Comparison of the fatty acid composition of subcutaneous adipose tissue from mature Brahman and Hereford cows.

The fatty acid composition of adipose tissue was measured in 37 mature Brahman and 32 mature Hereford cows to determine breed effect. Diet was held constant among all cows. When biopsied, cows were on oats and native cool-season annual pastures of good quality. Real-time ultrasound measurements of subcutaneous fat were taken at three locations (between the 12th and 13th rib, at the rump, and at the perianal region) to determine overall fatness. Overall fat thickness from these measurements was 1.3 cm for Brahman cows and 1.7 cm for Hereford cows (P < .01). Subcutaneous adipose tissue biopsy samples were collected from the perianal region, and fatty acid composition was determined using a gas chromatograph. Fatty acids were expressed in both normalized (area percentage) and gravimetric (grams/100 grams of fresh tissue) formats. In addition to greater overall subcutaneous fat thickness, Hereford cows contained 5 g more of fatty acids per 100 g of fresh adipose tissue than Brahman cows (P < .05). Subcutaneous adipose tissue from Hereford cows was higher (P < .01) in total saturated fatty acids and lower in mono- and polyunsaturated fatty acids than subcutaneous adipose tissue from Brahman cows. Compositional differences remained when breeds were compared by analysis of covariance at a common body fatness. The data suggest a genetic basis for the differences in fatty acid composition of Brahman and Hereford cows.

Adipose Tissue↗
PubMed1993

Tissue-specific activity of pentose cycle oxidative enzymes during feeder lamb development.

Relationships between pentose cycle oxidative activity and differential fat growth were evaluated. Rambouillet wether lambs (n = 60) were slaughtered serially at 0, 40, 80, and 120 d on feed (15 lambs/group). Rack dissection and kidney fat weights were collected, and longissimus muscle i.m. fat content was determined. Postmortem longissimus muscle, s.c. fat, intermuscular fat (INT), and kidney fat (KP) samples were assayed in vitro for glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activity (nanomoles.minute-1.gram of tissue-1), and samples were subjected to electrophoresis (PAGE) to separate tissue-specific isoforms. Allometric coefficients for rack components indicated that s.c. fat was the earliest-maturing, slowest-growing depot, INT was the latest-maturing, fastest-growing depot, and i.m. fat was intermediate (P < .05). Kidney fat grew faster than carcass weight and, as carcass weight increased, the growth rate of KP accelerated (P < .05). Enzyme activities increased until 40 d on feed and declined thereafter. Activities differed across tissues and time on feed end points (P < .05). Ratios of G6PDH:6PGDH, reflecting flux through the oxidative phase of the pentose cycle and, therefore, lipogenic activity, suggested growth patterns similar to those indicated by allometric analysis, except in the i.m. fat depot. Development of i.m. fat initially was intermediate to KP and INT, but G6PDH:6PGDH ratios increased with time on feed, suggesting a different regulatory mechanism and maturing pattern. Multiple forms of G6PDH were detected with PAGE, and although polymorphism was not detected, a tissue-specific isoform was isolated for INT fat.

Adipose Tissue↗
PubMed1993

Opsin synthesis in the C57BL/6-mivit/mivit mouse model of retinal degeneration.

The capacity of photoreceptor cells to synthesize opsin was evaluated in a newly-described mouse model of retinal degeneration, the C57BL/6-mivit/mivit. The mivit/mivit mouse loses photoreceptor cells at a rate of about one row per month beginning at 8 weeks, ROS are severely disrupted at 4 months, RPE is unevenly pigmented. Retinas of affected and control mice ages 4, 6, 8, 12, 16, 20, 24, 28, 32 and 52 weeks were incubated for 2 hours in medium containing [3H] leucine. Homogenates of retina samples were subjected to SDS-PAGE using disc gels. The gels were sliced and counted by scintillation. The incorporation of [3H] leucine into opsin was compared with its incorporation into other retinal proteins. During the early time points studied, mivit/mivit retinas incorporated proportionately similar amounts of [3H] leucine into opsin versus other retinal proteins as did controls. At 12 weeks, the percentage was about 80% and it continued to decline over the succeeding weeks studied. By 1 year, the proportion of leucine incorporated into opsin versus other proteins was only about 23% the amount incorporated in controls. The results of the present study suggest that the mivit/mivit photoreceptor cells are able to synthesize opsin and the gradual decline in synthetic ability follows the gradual loss of cells and is not correlated with the disruption of ROS.

Aging↗