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Biomedical subjects

M A Parsons

Publications and source records attributed to M A Parsons.

At least 55 records · Page 3Linked to original sources
PubMed1998

One-two rural residency tracks in family practice: are they getting the job done?

BACKGROUND: In the 1990s, the Residency Review Committee for Family Practice (RRCFP) and the American Board of Family Practice used the development of rural training programs as a strategy to bridge training experiences across urban referral centers and rural community hospitals. These programs are relatively small and attract trainees who are predisposed to rural practice. Aggregating data from several programs yields insight about their challenges and their ability to produce graduates who enter rural practice. METHODS: This descriptive analysis is based on self-reported data from a 1996 survey mailed to the residency program directors of rural training programs, identified by the RRCFP office as one-two programs. RESULTS: More than half of the rural training programs surveyed were located in health professions shortage areas, most in communities with little urban influence. These programs are equally likely to be sponsored by university- or community-based residency programs. Most (75%) placed two or fewer residents per year in the rural site; minorities accounted for 4% of placements. Thirty percent of programs report unfilled positions. Seventy-five percent use televideo communications and find experiences in surgery and obstetrics relatively easy to arrange but dermatology and critical care difficult. Seventy-six percent of graduates enter rural practice after graduation. CONCLUSIONS: This survey suggests that family practice rural one-two residencies are meeting the goal of providing trainees with a rural immersion experience, in anticipation of selecting rural practice after graduation.

Community Health Services↗
PubMed1998

Involvement of calcium in retinal pigment epithelial cell proliferation and pigmentation.

PURPOSE: The aim of this study is to explore the role of intracellular calcium in the mechanism of co-regulation of retinal pigment epithelial cells (RPE) by vitreous fluid and platelet mitogens, in order to evaluate the use of calcium modulating drugs in preventing RPE cell proliferation and contraction of fibrocellular membranes. METHODS: Monolayers of human RPE cells were loaded with Fura-2-AM and examined in a fluorimeter for changes in intracellular free calcium in response to platelet mitogens (PDGFAB or TGFbeta1) and vitreous fluid (containing vitreous substrate proteins), both alone or in combination. The effect of the calcium antagonists TMB8 and verapamil and the calmodulin antagonists J8 and tamoxifen were then examined on RPE cell proliferation and pigmentation, both in the presence and absence of vitreous substrate and platelet mitogens. RESULTS: We report that co-exposure of RPE cells to platelet mitogens and vitreous fluid produces an increase in intracellular free calcium of greater duration than that with either PDG-FAB, TGFbeta1 or vitreous fluid alone. Calcium and calmodulin antagonists significantly reduce RPE cell proliferation in both the presence and absence of vitreous substrate and platelet mitogens. Calcium antagonists also stimulate the accumulation of autofluorescent granules within RPE cells. CONCLUSIONS: Calcium signalling plays a role in the co-regulation of RPE cells by vitreous substrate and platelet mitogens. Drugs that lower intracellular calcium or inhibit calmodulin may offer an additional approach to preventing the hyperproliferation of RPE cells in PVR.

Adult↗
PubMed1997

Abnormalities of chromosomes 3 and 8 in posterior uveal melanoma correlate with prognosis.

Posterior uveal melanomas have nonrandom alterations affecting chromosomes 3, 6, and 8. Loss of chromosome 3 in uveal melanoma has been shown to act as a predictor of disease-free and overall survival. To confirm the significance of chromosome 3 loss and to extend the observations to include those of the associated alterations of chromosome 8, we have conducted a cytogenetic analysis on a series of 42 tumours from patients with primary uveal melanoma who were followed up for a median of 31 months (range = 8-96 months). Abnormalities of chromosomes 3 and 8 were the commonest changes and were confirmed in 10 tumours using fluorescence in situ hybridization. Monosomy of chromosome 3 was found in 21 (50%) of the tumours, and 23 (54%) tumours had additional copies of 8q. Alterations of chromosomes 3 and 8 were found occurring together in 19 (45%) of the tumours and were significantly associated with a ciliary body component (P < 0.0001). Prognostic indicators and changes of chromosomes 3 and 8 were analysed for correlation with patient survival. Of the chosen parameters, only ciliary body involvement (P = 0.003), monosomy of chromosome 3 (P = 0.0007), and additional copies of 8q (P = 0.003) correlated with reduced survival. Evaluation of the dosage effect of additional copies of chromosome arm 8q showed a significant association with reduced survival (P = 0.0001), which was also predictive of a decreased disease-free interval (P = 0.01). Thus, the cytogenetic analysis of uveal melanoma may provide a valuable predictor of prognosis.

Adult↗
PubMed1997

Physical activity and physical fitness in African-American girls with and without obesity.

Lack of physical activity and low levels of physical fitness are thought to be contributing factors to the high prevalence of obesity in African-American girls. To examine this hypothesis, we compared habitual physical activity and physical fitness in 54 African-American girls with obesity and 96 African-American girls without obesity residing in rural South Carolina. Participation in vigorous (> or = 6 METs) (VPA) or moderate and vigorous physical activity (> or = 4 METs) (MVPA) was assessed on three consecutive days using the Previous Day Physical Activity Recall. Cardiorespiratory fitness was assessed using the PWC 170 cycle ergometer test. Upper body strength was determined at two sites via isometric cable tensiometer tests. Relative to their counterparts without obesity, girls with obesity reported significantly fewer 30-minute blocks of VPA (0.90 +/- 0.14 vs. 1.3 +/- 0.14) and MVPA (1.2 +/- 0.18 vs. 1.7 +/- 0.16) (p < 0.01). Within the entire sample, VPA and MVPA were inversely associated with body mass index (r = -0.17 and r = -0.19) and triceps skinfold thickness (r = -0.19 and r = -0.22) (p < 0.05). In the PWC 170 test and isometric strength tests, girls with obesity demonstrated absolute scores that were similar to, or greater than, those of girls without obesity; however, when scores were expressed relative to bodyweight, girls with obesity demonstrated significantly lower values (p < 0.05). The results support the hypothesis that lack of physical activity and low physical fitness are important contributing factors in the development and/or maintenance of obesity in African-American girls.

Black People↗
PubMed1997

Demographic factors: interaction effects on health-promoting behavior and health related factors.

The purpose of this study was to examine the main and interaction effects of race, gender, and education on health-promoting behaviors, problem solving appraisal, health value, and health definition. Using a convenience sample of 331 employees, a series of three-way ANOVAs were performed. Only gender exerted main effects on health-promoting behaviors, including exercise, relaxation, and health promotion. No interaction effects were presented. Neither main nor interaction effects were found for approaching problems and having confidence in solving problems. However, interaction effects indicated that better educated women and better educated black employees perceived less personal control when solving problems. Women valued health more than men, even though there were no gender, race or education differences in the sample's definition of health. Community health nurses and workplace wellness planners are challenged to design programs sensitive to gender differences regarding health behaviors and the valuing of health. Developing training programs to enhance personal control over problem situations is also indicated.

Adult↗
PubMed1997

Health-promoting behaviors of black and white college women.

There is growing recognition that race and socioeconomic variables in health research demand greater attention. The investigators compared racial differences in health definition, health value, and health-promoting behavior of 62 pairs (N = 124) of Black and White college women matched on age, body mass index, and socioeconomic status. Both groups of women had similar definitions of health, valued health to the same extent, and reported similar levels of self-actualization, health responsibility, exercise, and stress management. Black women, relative to White women, practiced fewer nutrition behaviors and had less interpersonal support. Interventions to reduce health risk associated with nutrition practices of Black women are warranted and further research is needed to explore the influence of the social structure of educational institutions on interpersonal relationships and other health behaviors. When socioeconomic status is taken into consideration, Black and White college women demonstrated more commonalities in health behavior than differences.

Black or African American↗
PubMed1996

Predictors of alcohol use among rural adolescents.

There is increasing evidence that alcohol use is becoming more common during childhood and early adolescence. However, little is known about alcohol use among rural youths. This article reports a study of alcohol use among 367 fifth-grade students in two rural South Carolina school districts. More than one third (n = 131) of the fifth graders reported having used alcohol. Of these, 34 percent (n = 44) reported drinking during the previous month; 8 percent had been intoxicated during the previous two months; and 54 percent reported drinking in the home with or without parental approval. Logistic regression analysis was used to determine the predictors of alcohol use by fifth graders. The results indicated that gender (OR = 2.82), mother's alcohol use (OR = 1.86), father's alcohol use (OR = 2.13), and smoking (OR = 8.30) were significantly associated with alcohol use. The findings suggest that prevention programs address cigarette smoking and drinking behaviors of parents to reduce alcohol use and the acquisition of other health compromising behavior by youths. Early intervention approaches must go beyond the schools and target families as well as community populations.

Adolescent↗
PubMed1996

Ocular and cerebral trauma in non-accidental injury in infancy: underlying mechanisms and implications for paediatric practice.

AIMS: To determine the sites, mechanisms, and clinical significance of injuries to the eyes and brains of children with non-accidental injuries in relation to differing levels of trauma. METHODS: A forensic pathological study of injuries in the eyes and brains of 23 consecutive children dying of non-accidental injuries over a 4 year period (1988-92) under the jurisdiction of Yorkshire and Humberside coroners. RESULTS: Sixteen children died from cerebral injuries and seven died from non-cerebral causes. There were high incidences of retinal detachment (63%) and subhyaloid (75%), intraretinal (75%), and perineural (68%) haemorrhages in CNS deaths. Local subhyaloid haemorrhages and retinal detachment were more common at the periphery and optic disc than at the equator. There was a strong correlation between CNS and eye trauma scores in all 23 children (r = 0.7551, p < 0.0001). Ranking of injuries by severity suggests progressively more trauma required for (a) subdural haemorrhage, (b) subhyaloid, intraretinal, perineural haemorrhages, and (c) retinal detachment. At highest trauma levels choroidal and vitreous haemorrhages were associated with additional cerebral lacerations, intracerebral and subarachnoid haemorrhages. CONCLUSIONS: In non-accidental (and probably accidental) infantile head injury the earliest eye injuries (coinciding with subdural haemorrhage) could be missed if indirect ophthalmoscopy is not performed. Retinal detachment and multiple (particularly choroidal/vitreous) haemorrhages may indicate additional cerebral lacerations and/or intracerebral haemorrhage. Vitreous traction is the likely cause of intraocular pathology.

Battered Child Syndrome↗
PubMed1996

Human ocular melanocytes and retinal pigment epithelial cells differ in their melanogenic properties in vivo and in vitro.

PURPOSE: The vertebrate eye contains both melanocytes and retinal pigment epithelial (RPE) cells. Little is known of the pigmentary behaviour of these embryologically dissimilar cells. The aim of this study was to examine aspects of the pigmentary properties of both cell types in vitro and ex vivo to learn more of the function of these cells. METHODS: Sections of normal adult human eye were stained for tyrosinase related protein 1(TRP1), and cultures of RPE cells and choroidal melanocytes were examined immunocytochemically for TRP1 and 2 and enzymatically for tyrosinase activity (by assaying dopa oxidase activity). RESULTS: Over half of the choroidal melanocytes expressed TRP1 ex vivo; in contrast, a very small percentage of RPE cells were TRP1 positive. In vitro, passage 1 to 3 ocular melanocytes expressed TRP1 and TRP2 and had tyrosinase activity, which was influenced by the choice of substrate on which the cells were grown. Tyrosinase activity was highest when cells were grown on fibronectin and plastic, intermediate on laminin and lowest on vitreous extracellular matrix (ECM) containing pigment to which they attached and spread out poorly. In contrast, passage 3 RPE cells (which were unpigmented) showed little evidence of tyrosinase activity in short-term culture, irrespective of the substrate on which they were grown, and failed to express TRP1 and TRP2. When cells were grown on plastic for greater than 3 weeks in culture, a very low percentage of cells (< 0.1%) became TRP1 positive and this percentage was increased threefold if cells were cultured on laminin in the presence of bFGF. A few cells were also seen to contain pigment but cultures failed to show any tyrosinase activity. In contrast, RPE cells (but not melanocytes) showed a marked ability to take up pigment granules in vitro. CONCLUSIONS: The data suggest that normal human ocular melanocytes retain the capacity to produce pigment throughout adult life, and this can be demonstrated both ex vivo and in vitro. In contrast, we were unable to confirm that the majority of RPE cells play any significant role in active pigment production in the adult.

Adult↗
PubMed1996

Additive effects of extra cellular matrix proteins and platelet derived mitogens on human retinal pigment epithelial cell proliferation and contraction.

PURPOSE: In proliferative vitreoretinopathy (PVR) retinal pigment epithelial cells (RPE) cells are thought to synthesize and interact with extracellular matrix (ECM) proteins to form fibrocellular membranes attached to the retina, which the cells then progressively contract detaching the retina. Haemorrhage into the eye is an exacerbating factor in the pathology. To investigate some of the possible interactions between ECM proteins, platelet mitogens and RPE cells in this study, we examined the combined effect of platelet derived mitogens and ECM proteins on RPE cell proliferation and contraction. METHODS: Cells were cultured on a range of individual ECM proteins as well as on the ECM deposited by normal vitreous fluid and exposed to platelet mitogens. Effects on cell proliferation and cell detachment from these substrates and tissue culture plastic were examined. RESULTS: We report additive/synergistic effects of platelet mitogens (PDGF and TGFb1) as well as bFGF, with ECM proteins (laminin, fibronectin, collagen 1 and vitreous-deposited ECM) on RPE proliferation. Further we report stimulation of RPE cell contraction on vitreous proteins when exposed to serum prepared from platelet-rich plasma. In this context it was noticeable that it was cells grown on vitreous matrix plus pigment rather than cells grown on clear vitreous that exhibited this behaviour. CONCLUSIONS: This study supports a combined action of platelet mitogens and matrix proteins in inducing RPE cell proliferation and contractility and provides a simple in vitro model of some of the late stages of PVR.

Blood Platelets↗
PubMed1995

Involvement of anterior chamber angle structures in disseminated histoplasmosis: report of three cases.

This study describes the involvement of anterior chamber (AC) angle structures in patients with disseminated histoplasmosis. The postmortem eyes from three patients (aged 33, 41, and 42 years, respectively) with disseminated histoplasmosis, two of whom had acquired immunodeficiency syndrome, were examined by light microscopy using hematoxylin-eosin, periodic acid-Schiff (PAS), and Gomori's methenamide silver (GMS) stains. Electron microscopy studies of the choroid were performed in one eye. Significant numbers of budding yeast forms of Histoplasma capsulatum measuring 2-5 microns in diameter were observed within the trabecular meshwork, Schlemm's canal and in the deep intrascleral plexuses. All eyes showed massive involvement of the choroidal vasculature, including the choriocapillaris. The organisms were observed freely as well as in small clusters within the cytoplasm of circulating monocytes. The vessels of the limbal conjunctiva (two eyes) and ciliary body (three eyes) contained many Histoplasma organisms. In one eye, several budding yeast were noted in an iris vessel and in occasional histiocytes within the ciliary muscle. Blood smears containing Histoplasma organisms were observed in two cases. None of the patients had an ophthalmologic examination prior to death. Involvement of the intravascular structures of the eye as well as the AC angle was observed in three patients with disseminated histoplasmosis. The fungus most likely reached the AC angle structures by direct hematogenous dissemination or via the aqueous humor by migration from vessels in the ciliary body and iris. An abnormal retrograde blood flow into the AC angle structures may have also played an important role. We suggested that the intraocular pressure be monitored in cases of suspected disseminated histoplasmosis to detect functional alterations indicative of a blockage in the outflow channels.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Xanthogranulomatous cholecystitis.

Clinical, radiological and pathological findings in 31 patients with xanthogranulomatous cholecystitis have been reviewed. The spectrum of presentation was similar to that of cholelithiasis but fewer patients had biliary colic (17 per cent) and there were more complications (32 per cent). Four patients had a biliary fistula and four a perforated gallbladder with abscess formation. Patients characteristically had gallstones. Appearances often mimicked carcinoma of the gallbladder at ultrasonography and/or laparotomy, with xanthogranulomatous tissue extending to adjacent structures. Xanthogranulomatous cholecystitis and carcinoma of the gallbladder coexisted in three patients. The possibility should be considered that an 'inoperable tumour' of the gallbladder may in fact be xanthogranulomatous cholecystitis, a benign condition that frozen-section biopsy may confirm.

Adult↗
PubMed1994

Primary sebaceous carcinoma of lacrimal gland: a previously unreported primary neoplasm.

We describe a patient who presented with a rapidly growing neoplasm of the lacrimal gland which histologically was a sebaceous gland carcinoma. The eyelid was entirely normal on examination under anaesthesia. Sebaceous differentiation has been described on only three previous occasions, arising within pre-existing tumours of the lacrimal gland such as pleomorphic adenoma. In this case there is a single tumour cell line within normal lacrimal gland, and the eyelid is normal. This points to a previously unreported diagnosis of primary sebaceous carcinoma of the lacrimal gland.

Adenocarcinoma, Sebaceous↗
PubMed1994

Factors influencing physical activity in average-weight and overweight young women.

Young women are a specific population that is falling short of performing what is considered to be an optimal level of physical activity. The purpose of this study was to determine the ability of nine explanatory variables to predict physical activity in a sample of average-weight (n = 225) and overweight (n = 115) young women. Personal control, race, regular participation in organizations and groups, and interpersonal support were the significant predictors of physical activity in overweight women. For average-weight women, only three variables--personal control, regular participation, and race--were significantly related to physical activity. Recreational activity was routinely performed by 25% of the women. Of the 14% who reported regular vigorous physical activity, 26% were White and 10% were Black. The findings suggest that nurses in community settings design interventions that are sex and race specific and that include personal-control skill building, interpersonal support systems, and multiple forms of physical activity, particularly recreational forms.

Adolescent↗