Biomedical subjects

M Jones

Publications and source records attributed to M Jones.

At least 397 records · Page 22Linked to original sources

PubMed1996

Evaluation of aortic regurgitation with digitally determined color Doppler-imaged flow convergence acceleration: a quantitative study in sheep.

OBJECTIVES: The aim of the present study was to validate a digital color Doppler-based centerline velocity/distance acceleration profile method for evaluating the severity of aortic regurgitation. BACKGROUND: Clinical and in vivo experimental applications of the flow convergence axial centerline velocity/distance profile method have recently been used to estimate regurgitant flow rates and regurgitant volumes in the presence of mitral regurgitation. METHODS: In six sheep, a total of 19 hemodynamic states were obtained pharmacologically 14 weeks after the original operation in which a portion of the aortic noncoronary (n = 3) or right coronary (n = 3) leaflet was excised to produce aortic regurgitation. Echocardiographic studies were performed to obtain complete proximal axial flow acceleration velocity/distance profiles during the time of peak regurgitant flow (usually early in diastole) for each hemodynamic state. For each steady state, the severity of aortic regurgitation was assessed by measurement of the magnitude of the regurgitant flow volume/beat, regurgitant fraction and instantaneous regurgitant flow rates determined by using both aortic and pulmonary artery electromagnetic flow probes. RESULTS: Grade I regurgitation (regurgitant volume/beat < 15 ml, six conditions), grade II regurgitation (regurgitant volume/beat between 16 ml and 30 ml, five conditions) and grade III-IV regurgitation (regurgitant volume/beat > 30 ml, eight conditions) were clearly separated by using the color Doppler centerline velocity/distance profile domain technique. Additionally, an equation for correlating "a" (the coefficient from the multiplicative curve fit for the velocity/distance relation) with the peak regurgitant flow rates (Q [liters/min]) was derived showing a high correlation between calculated peak flow rates by the color Doppler method and the actual peak flow rates (Q = 13a + 1.0, r = 0.95, p < 0.0001, SEE = 0.76 liters/min). CONCLUSIONS: This study, using quantified aortic regurgitation, demonstrates that the flow convergence axial centerline velocity/distance acceleration profile method can be used to evaluate the severity of aortic regurgitation.

Animals↗

PubMed1996

Evaluation of eccentric aortic regurgitation by color Doppler jet and color Doppler-imaged vena contracta measurements: an animal study of quantified aortic regurgitation.

To evaluate the utility of measurements of the color Doppler jet area, jet length, and width of the color Doppler-imaged vena contracta (the smallest flow diameter in any part of the flow acceleration field) as methods for quantifying aortic regurgitation (AR), eight sheep with surgically induced AR were studied. AR was quantified as peak and mean regurgitant flow rates, regurgitant stroke volumes, and regurgitant fractions as determined with pulmonary and aortic electromagnetic flow probes and flowmeters balanced against each other. Simple linear regression analysis between the maximal color jet areas, jet length, and flowmeter data showed only moderately good correlation (jet area: 0.42 < or = r < or = 0.57, SEE = 2.85 cm2; jet length: 0.42 < or = r < or = 0.59, SEE = 1.23 cm). In contrast, the width of color Doppler-imaged vena contracta was a better indicator of the severity of AR on the basis of the electromagnetic flowmeter methods (0.73 < or = r < or = 0.90, SEE = 0.15 cm). Therefore the color Doppler jet length and jet area methods have limited use for determining AR, whereas the width of the color Doppler-imaged vena contracta can be used for quantifying the severity of AR.

Animals↗

PubMed1996

Cisapride as a treatment for gastroparesis in traumatic brain injury.

Gastroparesis is a well-documented finding among patients with severe traumatic brain injuries. The treatment of choice has been metoclopramide, but it is less than ideal given its central dopaminergic blocking activity. Cisapride is a newer prokinetic agent without side effects on the central nervous system and might be a superior treatment. The case of a healthy 22-year-old man who suffered a severe traumatic brain injury and multiple trauma in a motor vehicle accident is reported. The patient required gastrostomy tube placement but developed recurrent aspiration pneumonia once feedings were initiated. Despite receiving metoclopramide, barium studies revealed gastroparesis, a significant decrease in gastric peristalsis, and reflux. A jejunostomy tube was placed to prevent further aspiration. The administration of cisapride was begun, and 2 days later the patient was changed back to G-tube feedings with no evidence of residual aspirates. Repeat barium study showed definite improvement in peristalsis. This case demonstrates the potential usefulness of cisapride in patients with traumatic brain injury. Although further research is necessary, efficacy without central dopamine blockage may make cisapride the treatment of choice for gastroparesis and reflux in traumatic brain injury.

Adult↗

PubMed1996

Overexpression of p53 in tall cell variants of papillary thyroid carcinoma.

BACKGROUND: The tall cell variant (TCV) is a clinically aggressive subtype of papillary thyroid cancer. The aim of this study was to discover the prevalence of mutant forms of p53 protein in this subtype and relate it to clinical outcome. METHODS: Eighteen patients with TCV and a control group with common papillary cancers, matched for age and gender, were studied. The p53 mutations were identified by means of immunohistochemical staining. Data reviewed were overall survival, recurrence, TNM stage, and p53 positivity. RESULTS: p53 mutations occurred in 11 (61%) patients with TCV compared with two (11%) in control group (p = 0.05). In the TCV group two patients died of the disease (11%) and eight (44%) had local recurrences or distant metastases compared with none in the control group. All deaths and 70% of the recurrences occurred in patients with stage III or IV disease. p53 positivity did not correlate with any reduction in survival (7% compared with 9%) but with increased rate of local (23% compared with 4%) and distant (23% compared with 13%) recurrences. CONCLUSIONS: TCV was associated with a significantly higher rate of p53 positivity than common papillary carcinoma. The stage of the disease seemed to be a better prognostic indicator than p53 positivity for overall survival.

Adult↗

PubMed1996

"Inadvertent" thrombolytic administration in patients without myocardial infarction: clinical features and outcome.

STUDY OBJECTIVES: Increasing pressure to deliver thrombolytic agents quickly to patients with suspected myocardial infarction (MI), along with expanded indications, may contribute to inappropriate administration of these agents, with potentially catastrophic results. We sought to identify the extent to which MI is ruled out in patients given thrombolytic therapy for acute MI and to characterize the clinical course and outcome in such patents. METHODS: We studied 609 consecutive patients admitted to the CCU of an urban teaching hospital who were treated with thrombolytic agents for suspected acute MI between January 1986 and December 1993. In 35 (5.7%), MI was ruled out on the basis of persistently normal serum creatine kinase-MB isoenzyme levels. Hospital course and alternative diagnoses were established by means of chart review and database inquiry. RESULTS: Patients in whom MI was ruled out were similar to those with MI with regard to baseline demographic and clinical features. Presenting ECGs in patients without MI were less likely to show Q waves (43 versus 64%, P < .02) but more likely to show left ventricular hypertrophy (26 versus 7%, P = .001) and nonspecific ST-segment and T-wave changes (54 versus 32%, P < .01) compared the ECGs of MI patients. Transient ST-segment elevation was detected in 51%. Hospital complications of patients without MI were similar to those of MI patients. No patient in whom MI was ruled out sustained a major hemorrhage. Final diagnoses of patients without MI included unstable angina (n = 20, 57%) undefined chest pain (n = 8, 17%) pericarditis (n = 3), pancreatitis (n = 2), esophagitis (n = 1), and aortic dissection (n = 1). Two patients died, one of aortic dissection and another of pericarditis. CONCLUSION: In a consecutive series of CCU patients in whom MI was ruled after thrombolysis, we found no demographic or presenting clinical features to distinguish them from patients in whom MI was diagnosed. Transient ST-segment elevation potentially justifying thrombolytic therapy was present in more than half of the patients in whom MI was ruled out but may have represented transient coronary occlusion, coronary spasm, or other manifestations of unstable angina. In this study, patients in whom MI was ruled out had a high incidence of coronary disease and risk of in-hospital complications similar to that of patients with acute MI. Our findings support the rationale and safety of policies to rapidly and aggressively administer thrombolytic agents in the emergency department.

Aged↗

PubMed1996

The role of the periodontal ligament in bone modeling: the initial development of a time-dependent finite element model.

Current remodeling theories, as applied to long bones, suggest that such processes are controlled by mechanical strains either within or on the bone surface. In this study, the stresses and strains within the periodontal ligament and surrounding bone, consequent to orthodontic loading of a tooth, were investigated by application of the finite element method. Previously, various authors have applied two and three dimensional instantaneous (essentially static) models to analyze the problems. The study reported in this article describes an initial time-dependent (continuous/dynamic) finite element model for tooth movement that uses newly developed software, the results being cross-referenced against historical data. These early results, from a two-dimensional mathematical model of a loaded canine tooth, suggest that the remodeling process may be controlled by the periodontal ligament rather than the bone. In the finite element model, bone was found to experience a low strain of 1 x 10(-5), whereas the periodontal ligament experienced a strain of 0.1 when the "tooth model" is loaded. Only this latter figure is above the threshold usually reported to be necessary to initiate the remodeling process. Further developments in this rapidly advancing area of biomechanical research should facilitate a greater increase in our knowledge of tissue stress and strain after loading.

Bone Remodeling↗

PubMed1996

MHC class II tolerant T cells undergo apoptosis upon re-exposure to tolerogen in vivo.

Tolerance of MHC class II alloantigens can be achieved by intravenous injection of semiallogeneic hematopoietic cells into neonatal mice. Lymphoid cells of tolerant mice fail to proliferate or secrete interleukins IL-2 or IL-4 when stimulated in vitro with tolerogen. Since the lymphoid organs of B10.T(6R) tolerant mice contain normal levels of I-E reactive (V beta 11+) CD4+ T cells, deletion of alloreactive T cells does not appear to be the mechanism involved in the tolerance induction. To test whether T cells from tolerant animals can become activated under conditions that do not involve alloantigen stimulation, we stimulated these cells with immobilized anti-V beta 11 antibodies. Spleen cells from grafted tolerant and rejector mice proliferated in response to anti-V beta 11+ antibodies, suggesting they were not inert. We then tested whether V beta 11+ T cells from grafted mice can be induced to proliferate following stimulation with alloantigen in vivo. We adoptively transferred T cells from grafted tolerant and rejector mice into irradiated (B10.AQR x B10.T(6R))F1 mice and harvested the lymphoid organs after 65 h. Cells from both grafted tolerant and rejector mice underwent blast transformation, but only cells from rejector mice proliferated when exposed to immobilized anti-V beta 11 antibodies. The failure of V beta 11+ cells from tolerant mice to proliferate after in vivo stimulation may be because they are apoptotic. To test this hypothesis, spleen cells from naive or neonatally tolerized (with (B10.AQR x B10.T(6R))F1 cells) B10.T(6R) mice were adoptively transferred into irradiated (B10.AQR x B10.T(6R))F1 mice and bcl-2 expression was analysed in harvested V beta 11+ cells. Large cells recovered from recipients of naive 6R cells expressed bcl-2 mRNA. By contrast, large cells harvested from recipients of tolerized 6R cells did not express bcl-2 mRNA, suggesting bcl-2 mRNA expression was downregulated in these mice. Moreover, in another experiment, large V beta 11+ cells from grafted tolerant animals recovered after transfer into irradiated (B10.AQR x B10.T(6R))F1 mice did not express the bcl-2 protein as determined by flow cytometry, and contained fragmented DNA as assessed by the TUNEL method. Taken together, these data suggest that MHC class II tolerant T cells undergo apoptosis upon re-exposure to tolerogen in vivo.

Animals↗

PubMed1996

Heterogeneous T cell receptor V beta gene repertoire in murine interstitial nephritis.

Anti-tubular basement membrane disease (alpha TBM) produces T cell-mediated interstitial nephritis in SJL/J mice following immunization with heterologous renal tubular antigen. Initial mononuclear infiltrates appear in vivo after six to eight weeks, with subsequent progression to renal fibrosis and endstage kidney disease. Cultured lymph node derived nephritogenic T cells from these mice react to a small epitopic region of the 3M-1 target antigen and share a common amino acid motif in their V beta CDR3 regions. We now have used RT-PCR to further characterize the renal expression of T cell receptor (TcR) V beta gene repertoires during the course of this disease. Individual kidneys with focal mononuclear infiltrates characteristic of early alpha TBM disease express up to three different TcR V beta genes; however, the same V beta genes are not found in all kidneys at the same early stage of injury. DNA sequencing of the V beta RT-PCR products reveals a heterogeneous population of VDJ recombinations and deduced CDR3 amino acid sequences. Our studies do not support TcR V beta region gene restriction in histologically-detectable alpha TBM disease, but are more consistent with a dynamic, organ-specific autoimmune disease, directed at multiple autoantigenic epitopes.

Amino Acid Sequence↗

PubMed1996

Follow-up evaluation of respiratory isolation rooms in 10 midwestern hospitals.

As a follow-up to a 1992 study or respiratory isolation, we studied compliance with recommendations for respiratory isolation through smokestick testing (1993) and surveys (1994). Effective negative pressure was demonstrated in 80 of 156 rooms and was associated with the presence of anterooms (P < .001). The proportion of surveyed hospitals periodically testing isolation rooms increased from 0% (1992) to 30% (1993) to 100% (1994; P < .001).

Cross Infection↗

PubMed1996

CD34+ progenitor cell selection: clinical transplantation, tumor cell purging, gene therapy, ex vivo expansion, and cord blood processing.

A unique avidin-biotin immunoadsorption system (CellPro CEPRATE SC) has been developed for the rapid clinical scale purification of CD34+ cells from bone marrow, mobilized peripheral blood (PBSC), or cord blood. This system has been used to treat more than 2500 patients worldwide in a variety of clinical studies. In the autologous transplantation setting, selection for CD34+ cells results in significant reduction (2- > 5 logs) of contaminating tumor cells in the enriched fractions, as documented using sensitive immunocytochemistry staining techniques or quantitative PCR analyses. In the allogeneic bone marrow or PBSC transplant setting, using the CEPRATE SC system as a method for T cell depletion has shown a 3-log reduction in overall T cell content, with more rapid hematopoietic recovery after PBSC reinfusion as compared with bone marrow. CD34+ enrichment is required for efficient ex vivo expansion of progenitor cells as well as for gene therapy applications involving the genetic modification of stem cells.

Antigens, CD↗

PubMed1996

Varicella zoster virus-specific cytotoxicity following secondary immunization with live or killed vaccine.

Subjects > or = 55 years of age were immunized with attenuated varicella zoster virus (VZV) vaccine (live) or with the same vaccine, which had been heated to 56 degrees C for 7 days (killed). The ability of subjects' blood lymphocytes to lyse target cells infected with VZV was determined before and 3 months after immunization using autologous Epstein-Barr virus (EBV) lymphoblasts as targets for human leukocyte antigen (HLA) class I restricted cytotoxicity and human fibroblasts as targets for unrestricted (natural killer [NK]) cytotoxicity. The live vaccine recipients showed an increase in their class I-restricted lysis of targets compared with the recipients of the killed vaccine. The two populations showed equivalent increase in their NK-dependent lysis of fibroblast targets. The results support the view that both the live and killed vaccines stimulate cytotoxicity by VZV-specific lymphocytes but that the live vaccine stimulates relatively more class I-restricted killing.

Aged↗

PubMed1996

Nosocomial outbreak of gastroenteritis due to Salmonella senftenberg.

We describe a prolonged nosocomial outbreak of Salmonella senftenberg, an uncommon human pathogen. We detected 22 cases of infection due to S. senftenberg that occurred from March 1993 through November 1994 and involved 18 patients and four healthy employees. All infected persons had consumed food prepared by the hospital kitchen. The estimated attack rate for the period of the outbreak was 0.19-0.23 cases per 100,000 meals served. Infection control interventions included observation of food preparation, disinfection of kitchen devices, and education of food handlers. The consumption of lettuce (11 of 15 patients who could recount extended dietary histories vs. 4 of 20 controls; P = .005), cauliflower (5 of 15 vs. 0/20; P = .02), cottage cheese (4 of 15 vs. 0/20; P = .03), and deli turkey (8 of 15 vs. 0/20; P < .001) was associated with S. senftenberg infection. The isolates had identical antibiograms and pulsed-field gel electrophoretic patterns. Cultures of stool samples from food handlers as well as food items, kitchen devices, and kitchen surroundings were negative for S. senftenberg. Interruption of the outbreak occurred coincidentally with the institution of infection control measures. This prolonged outbreak of salmonellosis was probably related to contamination in the kitchen from turkey, with cross-contamination via equipment.

Adult↗

PubMed1996

Pruritus and skin hydration during dialysis.

BACKGROUND: Dry skin is frequently observed in uraemic patients and a link with the common complaint of pruritus has been suggested. Objective data on skin dryness in haemodialysed patients is sparse and equivocal. No such information exists for the many patients now receiving peritoneal dialysis. We assessed the prevalence and severity of both pruritus and skin dryness in a uraemic population receiving maintenance dialysis. METHODS: Forty-eight haemodialysis and 24 peritoneal dialysis patients were examined and skin dryness assessed by clinical grading and measurement of stratum corneum hydration using a corneometer. Forty age- and sex-matched controls were also assessed. Several biochemical parameters with possible relevance to pruritus were measured. Regular emollient therapy was prescribed to pruritic dialysis patients and efficacy assessed. RESULTS: Dialysis patients overall had clinically drier skin than controls, especially the peritoneal dialysis group. Stratum corneum hydration levels were significantly reduced in the peritoneal dialysis (P < 0.004), but not the haemodialysis, population. Twenty-seven per cent of haemodialysed and 54% of peritoneal dialysis patients complained of pruritus. Pruritic patients in each dialysis group had significantly lower hydration than non-pruritic patients (P < 0.05). Regular emollient use in pruritic patients produced a marked reduction in severity of pruritus, abolishing the symptom in nine of 21 patients treated. CONCLUSION: Reduced stratum corneum hydration correlates with pruritus in patients on maintenance haemodialysis and peritoneal dialysis, and may be alleviated by simple emollient therapy.

Adolescent↗

PubMed1996

Does exposure to immunosuppressive therapy increase the 10 year malignancy and mortality risks in rheumatoid arthritis? A matched cohort study.

Rheumatoid arthritis (RA) is associated with increased mortality and an increased risk of neoplasms of the immune system (NIM). To establish whether immunosuppressive therapy alters these risks, a matched cohort study was conducted. The exposed cohort were 259 RA patients, resident in the UK, who first received immunosuppressive drugs (mainly azathioprine, cyclophosphamide and chlorambucil) between 1979 and 1982. The unexposed cohort were 259 patients matched for age, sex and disease, resident in the USA, who had never received immunosuppressives. Both cohorts had no prior reported malignancies and were followed for 10 yr. There was a small increase in mortality in the exposed compared to the unexposed cohort. Most of the excess deaths were due to malignancy. The relative risk (RR) of developing malignancy [1.5 (95% CI 0.9-2.3)] was lower than the RR of dying from malignancy [4.2 (95% CI 1.7-10.0)]. The RR of developing a NIM in the immunosuppressive-exposed group was 7.0 (95% CI 0.9-56.5). These results may be explained in part by differences in cancer registration and death rates between the UK and the USA. Nevertheless, the results suggest that exposure to immunosuppressive therapy increases the 10 yr malignancy risk in RA, but not mortality from other causes.

Adult↗

PubMed1996

School-based health services.

Children, particularly adolescents, have unique health care needs and experience frequent barriers to receiving needed medical care. The expansion of school-based health services since the early 1970s is one recent development in the area of health services delivery that is a specific response to facilitate meeting the medical needs of youth. Limited resources, shrinking budgets, demographic and behavioral changes among our nation's youth, and recent trends toward managed care all demand innovative strategies by school-based health services if they are to ensure their viability in providing adequate health care to children and adolescents. This article reviews the recently published literature regarding the role of school-based health centers as sites providing primary care services to children and adolescents. In addition, it addresses recent efforts to develop strategies that school-based health centers may need to consider in order to adapt and survive within the environment of health care reform and managed care.

Adolescent↗

PubMed1996

Cigarette smoking at hire as a predictor of employment outcome.

We have reported that cigarette smoking at the time of hire is associated with elevated rates of accidents, injuries, absence, discipline, and firing among US postal workers. We followed this cohort of 2537 for a second year to assess whether these associations would change with time in a workplace with active smoking cessation programs. Smokers' elevated risks for accidents, injuries, and discipline decreased after the first year. Risk for involuntary turnover was slightly higher in the 2-year analysis. The elevation in the rate of absence for smokers remained comparable in both periods. Although it is possible that the decline in the relative risk of accidents, injuries, and discipline may reflect changes in smoking status, we were unable to obtain follow-up data on smoking status to test this hypothesis.

Absenteeism↗

PubMed1996

The relationship of perceived benefits of and barriers to reported exercise in older African American women.

The purpose of this descriptive study was to determine the perceived benefits of and barriers to exercise of a convenience sample of older African American women in senior citizen centers in an urban area in the mid-South. This descriptive study utilized a convenience sample of older African American women over 60 years of age and examined the relationship among their current exercise levels, their perceptions regarding the importance of exercise, and the benefits of and barriers to engaging in regular exercise. The level of exercise was measured using the Exercise scale of the Health Promotion Lifestyle Profile (HPLP), the perceptions of the importance of exercise were measured by a Cantril ladder, and the benefits of and barriers to exercise were measured by the Exercise Benefits/Barriers Scale (EBBS) and one open-ended question on perceived barriers. A significant relationship was found between reported exercise levels and perceived benefits of and barriers to exercise (p < 0.001). Benefits most cited by participants reflected those categorized as life enhancing. Barriers cited most often related to exercise accessibility and availability. Results of this study support the need for community-based exercise programs for specific populations. Nursing interventions are needed that help women in general and African American women in particular to adopt exercise as a daily health-promotive activity.

Black or African American↗

PubMed1996

A Novel Strategy for Control of Microbial Biofilms through Generation of Biocide at the Biofilm-Surface Interface.

Biofilms of a mucoid clinical isolate of Pseudomonas aeruginosa (24 h; ca. 10(sup6) CFU/cm(sup2)) were established by immersion of polymer discs in nutrient broth cultures at 37(deg)C. Biofilms exposed for 30 min to various concentrations (0 to 3 mg/ml) of hydrogen peroxide or potassium monopersulfate were rinsed and shaken vigorously in sterile saline to detach loosely associated cells, and the residual viable attached population was quantified by a blot succession method on agar plates. Incorporation of copper and cobalt phthalocyanine catalysts within the polymers significantly enhanced the activity of these oxidizing biocides towards biofilm bacteria by several orders of magnitude. Biofilms established on the control discs resisted treatment with concentrations of either agent of up to 3 mg/ml. Enhancement through incorporation of a catalyst was such that concentrations of potassium monopersulfate of as low as 20 (mu)g/ml gave no recoverable survivors either on the discs or within the washings. Catalysts such as these will promote the formation of active oxygen species from a number of oxidizing agents such as peroxides and persulfates, and it is thought that generation of these at the surface-biofilm interface concentrates the antimicrobial effect to the interfacial cells and generates a diffusion pump which further provides active species to the biofilm matrix. The survivors of low-concentration treatments with these agents were more readily removed from the catalyst-containing discs than from the control discs. This indicated advantages gained in hygienic cleansing of such modified surfaces.

Journal Article↗