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Biomedical subjects

J Turner

Publications and source records attributed to J Turner.

At least 199 records · Page 11Linked to original sources
PubMed1995

Size constancy in structure from motion.

The relative motions of points in a structure-from-motion display involving parallel projection provide depth information in an object-centered framework: differences in velocity do not reflect differences in distance from an eyepoint. In contrast, size constancy is generally regarded to be a perspective effect, based on the relationship between projected size and distance from an eyepoint. Five subjects judged the relative sizes of objects in structure-from-motion scenes. Although the scenes were displayed without perspective, judged size was related to the simulated separation in depth of the objects. These results suggest that relative depths recovered from object-centered information are incorporated into a viewer-centered framework.

Depth Perception↗
PubMed1995

Quinupristin/dalfopristin (RP 59500) therapy for vancomycin-resistant Enterococcus faecium aortic graft infection: case report.

A 46-year-old woman was admitted to the hospital with severe peripheral vascular disease, requiring multiple vascular surgical procedures. During the sixth hospital week, after prior therapy with multiple antibiotics, Enterococcus faecium was isolated as the only organism from an operating room culture of an infected aortic graft. Histological examination of the graft showed infiltration with polymorphonuclear leukocytes. Subsequently, cultures of an infected inguinal wound yielded Enterococcus faecium with mixed bacterial growth. Both isolates of Enterococcus faecium were resistant to all available antimicrobials, including ampicillin, vancomycin, tetracycline, chloramphenicol, and ciprofloxacin. Compassionate use therapy with quinupristin/dalfopristin (RP59500) was administered for 25 days, the patient's clinical condition improved, and wound healing occurred. Transient elevation of serum alkaline phosphatase was noted. This case demonstrates successful eradication of deep VREF infection by quinupristin/dalfopristin with good tolerance of prolonged therapy.

Anti-Bacterial Agents↗
PubMed1995

MDTV Telemedicine Project: technical considerations in videoconferencing for medical applications.

In spite of the many advances in technology, complex problems must be addressed in establishing and maintaining a telemedicine system. Although most such systems are built around interactive videoconferencing (IAVC) equipment, clinical requirements dictate that these systems offer more than traditional IAVC systems. Input from system users should be obtained early in the design process to ensure the functionality necessary to achieve maximum utilization. Surprisingly, audio, rather than video, signals may present the greatest challenge to achieving consistent, high-quality videoconferencing encounters. Audio technical problems can be frustrating for patients and providers alike and can undermine user confidence in IAVC as a vehicle for healthcare delivery. A capability for remote access and control of components at distant sites seems essential to providing cost-effective and technically reliable service.

Humans↗
PubMed1995

Autoproliferation in HIV-1-infected patients undergoing active HIV-1-specific immunotherapy.

We have observed a treatment-associated autoproliferative response in cultured peripheral blood mononuclear cells (PBMC) of asymptomatic HIV-1-infected subjects receiving a gp120-depleted, inactivated HIV-1 antigen in incomplete Freund's adjuvant (IFA; HIV-1 Immunogen). The frequency and magnitude of the autoproliferative response appeared to be dose-related (P < 0.05), and was not observed in subjects receiving IFA alone. Immunophenotyping of the proliferating cells demonstrated the presence of both CD4+ and CD8+ lymphocytes, with the CD4+ blasts almost exclusively expressing the CD45RO+ phenotype. A comparison of this response with the HIV-1-specific antigen stimulation responses in this cohort revealed a significant correlation between increases in HIV-1-specific cell-mediated immunity and autoproliferation (r2 = 0.61, P < 0.001). These findings suggest that immunization with the HIV-1 Immunogen induces an autoproliferative response that may reflect changes in HIV-1-specific cell-mediated immunity in infected individuals.

AIDS Vaccines↗
PubMed1995

Predictors of patient adherence to long-term home nebulizer therapy for COPD. The IPPB Study Group. Intermittent Positive Pressure Breathing.

STUDY OBJECTIVE: Patients with moderate to severe COPD are frequently prescribed expensive and complicated therapies that require adjustments in usual activities of daily living. However, little is known about factors that are associated with adherence to such treatment. The objective of this study was to identify characteristics of patients who were adherent to long-term home nebulizer therapy. DESIGN: Patients were stratified into two adherence groups based on average minutes of nebulizer use each day. A logistic regression model was developed to predict adherence based on baseline variables. A questionnaire was administered to patients to assess reasons for adherence to therapy. SETTING: Five clinical centers in the United States and Canada. PARTICIPANTS: Nine hundred eighty-five patients with moderate to severe COPD enrolled in the Intermittent Positive Pressure Breathing (IPPB) Trial. INTERVENTIONS: Long-term home IPPB and nebulizer therapy. MEASUREMENTS AND RESULTS: Altogether 50.6% of patients were adherent, and 49.4% were nonadherent. Among baseline variables, good adherence was predicted by white race, married status, abstinence from cigarettes and alcohol, serum theophylline level > or = 9 micrograms/mL, more severe dyspnea, and reduced FEV1 (p < 0.05). Subjects who were adherent to nebulizer therapy were older, better educated, had a stable lifestyle, were more likely to report that the therapy made them feel better, and were more likely to keep clinic appointments. CONCLUSIONS: Sociodemographic, physiologic, and quality of life variables were associated with adherence to long-term nebulizer therapy.

Adult↗
PubMed1995

Epidemiology of isosporiasis among persons with acquired immunodeficiency syndrome in Los Angeles County.

To determine factors associated with isosporiasis in persons with acquired immunodeficiency syndrome (AIDS) in Los Angeles County, data from the AIDS surveillance registry were analyzed for the eight-year period 1985-1992. Isosporiasis was reported in 127 (1.0%) of 16,351 persons with AIDS during the study period. Prevalence of infection was highest among foreign-born patients (3.2%), especially those from El Salvador (7.4%) and Mexico (5.4%), and in all persons of Hispanic ethnicity (2.9%). Persons with a history of Pneumocystis carinii pneumonia (PCP) were less likely than PCP-negative patients to have isosporiasis (0.2% and 1.4%, respectively, P < 0.01). A decrease in the prevalence of isosporiasis in patients negative for PCP was observed beginning in 1989 (P = 0.02). Prevalence decreased with age (P < 0.01, by chi-square test for trend). After controlling for multiple factors by logistic regression, isosporiasis was more likely to occur in foreign-born patients than in those born in the United States (adjusted odds ratio [OR] = 5.8, 95% confidence interval [CI] 3.4, 9.9, P < 0.001) and in Hispanics than in whites (non-Hispanics) (adjusted OR = 3.5, 95% CI 1.7, 7.2, P < 0.001). A prior history of PCP continued to be negatively associated with isosporiasis (adjusted OR = 0.2, 95% CI 0.1, 0.3, P < 0.001). Age and time remained independently associated with infection. These data suggest that isosporiasis among persons with AIDS in Los Angeles County may be related to travel exposure and/or recent immigration and that the use of trimethoprim-sulfamethoxazole (TMP-SMX) for PCP may effectively prevent primary infection or expression of latent isosporiasis. Physicians should have an increased index of suspicion for Isospora in AIDS patients with diarrhea who have immigrated from or traveled to Latin America, among Hispanics born in the United States, in young adults, and in those not receiving PCP prophylaxis. Food and water precautions should be advised and TMP-SMX prophylaxis considered for the prevention of Isospora infection for patients with human immunodeficiency virus infection who travel to Latin America and other developing countries.

AIDS-Related Opportunistic Infections↗
PubMed1995

A human retinal pigment epithelial cell line that retains epithelial characteristics after prolonged culture.

PURPOSE: A spontaneously arising, apparently transformed, cell line has been cloned from a primary culture of human retinal pigment epithelial (RPE) cells and has been subcultured more than 200 times. The similarities of these cells to human RPE cells in vivo have been determined. METHODS: The structure of the transformed cells has been determined by light and electron microscopy and by immunocytochemistry using antibodies that detect cytoskeletal and other proteins. The ability of the cell line to bind and phagocytose photoreceptor material has also been assessed by fluorescence and electron microscopy. The metabolism of all-trans-retinol has been investigated by incubation of the cells with 3H-all-trans-retinol and analysis of the metabolic products by high-performance liquid chromatography. RESULTS: The transformed cells possess an epithelial cobblestone morphology with intercellular junctional complexes containing N-cadherin. The cytoskeleton of these cells comprises cytokeratins that are characteristic of epithelial cells, together with actin, spectrin, and vimentin. The keratins expressed are those typical of RPE cells. The cells also express cellular retinaldehyde binding protein and retinol dehydrogenase activity but do not express retinoid isomerase or lecithin retinol acyl transferase activities. These cells also exhibit phagocytic activity. CONCLUSIONS: This cell line retains many of the metabolic and morphologic characteristics of RPE cells in vivo although there are some differences, particularly the loss of some enzymatic activities and cytoskeletal polarization. These cells should be useful in further studies of RPE cell metabolism and other functions.

Cell Line, Transformed↗
PubMed1995

Prospective randomised double-blind trial of the in vivo use of recombinant human erythropoietin in bone marrow transplantation from HLA-identical sibling donors. The Australian Bone Marrow Transplant Study Group.

Ninety one patients between the ages of 17 and 58 years undergoing histocompatible allogeneic transplants from sibling donors were entered into a double-blind randomised trial to evaluate the effect of human erythropoietin (rhu EPO) at a dose of 300 units per kg/day given thrice weekly by intravenous injection on erythropoiesis and on erythrocyte and platelet transfusion requirements. Dose was ceased when the haemoglobin exceeded 12g/dL and recommenced if the haemoglobin fell below 12 g/dL, at 150 units/kg/day. If the haemoglobin exceeded 12 g/dL on a further occasion, the dose of rhu EPO was not given. Patients received two units of erythrocytes when the haemoglobin dropped below 8.5g/dL and received platelet transfusions when the count dropped below 20 x 10(9)/L. Univariate analysis revealed a significantly higher reticulocyte count, haemoglobin concentration and bone marrow erythropoiesis after day 14 in the group receiving rhu EPO but this was not reflected in decreased erythrocyte transfusion (7 +/- 5 in controls versus 6 +/- 5 in rhu EPO group) or in platelet transfusions (11 +/- 7 in controls versus 11 +/- 9 in rhu EPO group). Hospitalisation in each group was the same (29 +/- 8 in the control group and 28 +/- 8 in the rhu EPO group). However, in the multivariate analysis, the administration of rhu EPO was associated with an 18% reduction in erythrocyte transfusion requirement when other variables were taken into account. No side-effects due to rhu EPO were detected in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

FK506 and cyclosporin A each inhibit antigen-specific signaling in the T cell line 171 in the absence of a calcium signal.

Antigen-specific signal transduction leading to IL2 induction and secretion in the T cell line 171 is augmented by association of p56lck with CD4. Although no change in cytoplasmic calcium level ([Ca2+]i) was detectable during antigen-specific signal transduction of 171-CD4+ cells, IL2 induction was inhibited by FK506 and CsA. Since these drugs are thought to act selectively by inhibiting calcineurin, a calcium-calmodulin-dependent protein phosphatase associated with activation of the IL2 promoter, we considered the possibility that calcineurin is constitutively active in 171 cells. However, we found no evidence for this because PMA failed to supplement any putatively active calcineurin to induce IL2 secretion. We suggest that IL2 secretion induced by antigen presentation to TCR/CD4/p56lck requires an FK506 and cyclosporin A-sensitive step which may be independent of calcium signaling. Rapamycin did not inhibit IL2 secretion induced by TCR/CD4/p56lck, emphasizing the specific action of FK506 and cyclosporin A.

Amino Acid Sequence↗
PubMed1994

An explanation for lagging strand replication: polymerase hopping among DNA sliding clamps.

The replicase of E. coli, DNA polymerase III holoenzyme, is tightly fastened to DNA by its ring-shaped beta sliding clamp. However, despite being clamped to DNA, the polymerase must rapidly cycle on and off DNA to synthesize thousands of Okazaki fragments on the lagging strand. This study shows that DNA polymerase III holoenzyme cycles from one DNA to another by a novel mechanism of partial disassembly of its multisubunit structure and then reassembly. Upon completing a template, the polymerase disengages from its beta clamp, hops off DNA, and reassociates with another beta clamp at a new primed site. The original beta clamp is left on DNA and may be harnessed by other machineries to coordinate their action with chromosome replication.

DNA↗
PubMed1994

Amyloid precursor protein secretion and beta A4 amyloid generation are not mutually exclusive.

The cellular factors regulating the generation of beta A4 from the amyloid precursor protein (APP) are unknown. Protein phosphorylation by protein kinase C (PKC) has been found to influence the processing and metabolism of APP. In this report, we show that in the human neuroblastoma cell line SY5Y, beta A4 generation from full-length APP is not changed by PKC activation whereas production of the non-amyloidogenic secretory fragment (APPsec) and of the C-terminal fragment of beta A4 (p3) are stimulated. In addition, beta A4 generation from the membrane inserted C-terminal 100 residues (SPA4CT) of APP is stimulated by PKC activation. Accordingly attempts to divert APP processing from the amyloidogenic, beta A4-generating, to the non-amyloidogenic, secretory, pathway, have to address the nature and regulation of the two pathways and/or of the process leading to the cleavage of APP at the C-terminus of the beta A4 domain. The data reported here suggest that these mechanisms are cell-type specific.

Amyloid beta-Peptides↗
PubMed1994

Plasma brain natriuretic peptide in assessment of acute dyspnoea.

Recognition of heart failure (HF) may be difficult in patients presenting with acute dyspnoea, particularly in the presence of chronic airways obstruction. Since increased secretion of the cardiac hormones atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) occurs early in the course of HF, we have assessed the value of measuring these hormones in plasma in the diagnosis of suspected HF in 52 elderly patients presenting with acute dyspnoea, and compared values with left-ventricular ejection fraction (LVEF), a standard measure of left-ventricular function, by radionuclide angiography. Patients were enrolled prospectively. On the basis of clinical findings, conventional tests, and response to specific treatment, 20 of the 52 patients were classified as having primary lung disorder (PLD), 12 as HF alone, and 20 as HF with underlying PLD (HF/PLD). Compared with findings in PLD patients, LVEF was significantly depressed in HF and HF/PLD patients (p < 0.001), whereas both plasma ANP and BNP were significantly increased (p < 0.001). Admission plasma BNP concentration more accurately reflected the final diagnosis of HF (93% sensitivity and 90% specificity when BNP > or = 22 pmol/L) than LVEF or plasma ANP concentration. When all patients were considered together, there were strong negative correlations between LVEF and log BNP (r = -0.7, p < 0.001) and log ANP (r = -0.59, p < 0.001). Our finding that plasma BNP is raised in dyspnoeic patients with HF but not in acutely breathless patients with PLD, suggests that rapid BNP assays may assist in the diagnosis of patients with acute dyspnoea.

Acute Disease↗
PubMed1994

Combined hyperthermia and immunotherapy treatment of multiple pulmonary metastases in mice.

The combination of immunotherapy and hyperthermia results in a greater reduction in tumour growth compared to either therapy used alone in a murine subcutaneous tumour model. To evaluate this combination further we tested it in a murine pulmonary metastasis model. Mice were given 5 x 10(5) MCA-105 sarcoma cells on day 0 intravenously resulting in the formation of pulmonary metastases. Mice were treated with local hyperthermia to the left hemithorax with a transcutaneous microwave applicator or with whole-body hyperthermia to 41 degrees C for 30 min on days 3 and 6. Immunotherapy included 5 x 10(7) syngeneic LAK cells administered on days 3 and 6 and interleukin-2 given intraperitoneally three times daily on days 3-7. Animals were killed on day 12 and pulmonary nodules enumerated. While the addition of whole-body hyperthermia to immunotherapy had no significant effect on tumour growth, the combination of local hyperthermia and immunotherapy significantly decreased the number of pulmonary nodules by 94% compared to controls in combined experiments. The mechanism of this beneficial effect may be related to increased trafficking of immune active cells to the tumour-bearing site, an increase in the sensitivity of tumour cells to lysis, or perhaps a local release of cytokines induced by hyperthermia. This study established the efficacy of combined immunotherapy and hyperthermia for the treatment of visceral metastases and provides impetus for the initiation of clinical trials.

Animals↗
PubMed1994

FK 506 and cyclosporin each block antigen-induced T cell receptor signalling that is dependent on CD4 co-receptor and operates in the absence of detectable cytoplasmic calcium fluxes.

The T cell hybridoma "171", which lacks CD4 but expresses T cell receptor (TCR) for hen egg white lysozyme, requires introduction of wild-type CD4 for antigen-mediated induction and secretion of interleukin-2 (IL-2). Mutant CD4, which fails to associate with the tyrosine kinase p56lck does not support IL-2 secretion, suggesting that a role of CD4 is to bring cytoplasmic p56lck into alignment for signal transduction to the IL-2 promotor. Using 171, 171-CD4 (wild-type) and 171-CD4 (mutant), we found that IL-2 secretion was inhibited by FK 506 and cyclosporin but not by rapamycin. However, this inhibition was not associated with calcium fluxes since no change in cytoplasmic free calcium levels ([Ca]i; resting level 80 nM) was detectable during antigen stimulation of the 171 or 171-CD4 cells. Thus, although FK 506 and cyclosporin inhibited calcium-dependent signalling to the IL-2 promoter via inhibition of the protein phosphatase calcineurin, it is possible that IL-2 induction via TCR/CD4 requires an FK 506 (and cyclosporin) sensitive step which is independent of cytoplasmic calcium changes.

Animals↗
PubMed1994

Women in medicine--socialization, stereotypes and self perceptions.

Eleven women in various specialities, including the academic and administrative spheres, were interviewed with regard to their experiences throughout their career. These women all held senior positions in Medicine and represent a broad age range (35-69 years). Information gathered during the interviews was analysed thematically in an attempt to develop a basis for further research examining predictors of success for women in medicine.

Adult↗
PubMed1994

Influence of asthma or allergies on the utilization of health care resources and quality of life of college students.

The objectives of this study were to describe the treatment regimens of college students with asthma or allergies, to determine how asthma or allergies affect the lives of college students, and to evaluate the health care resources utilized by college students with asthma or allergies. A mail survey was sent to 275 students who received treatment for asthma or allergies at the Thomson Student Health Center at The University of South Carolina (TSHC-USC) during the fall 1991 semester. This survey, consisting of 46 questions, covered three key areas: current asthma or allergy management, class and work days missed, and utilization of health care resources. Students with "asthma and allergy" missed on average 2.4 days of class during the fall semester, whereas those with "asthma only" and "allergy only" missed on average 0.8 day and 1.5 days of class, respectively. Students with "allergy only" appeared to have a greater interference in their daily class and academic activities than students with "asthma and allergy" and "asthma only." In conclusion, students reported interference in their college activities and reported missing days of work and school because of asthma or allergies. This study also showed that a majority of these college students have not received asthma or allergy patient education nor utilized appropriate asthma or allergy management skills.

Absenteeism↗
PubMed1994

Women's knowledge of emergency contraception.

BACKGROUND: More widespread use of emergency contraception could help to reduce the number of unwanted pregnancies. AIM: The objective of this study was to assess women's knowledge of emergency contraception. METHOD: A questionnaire was distributed to 1290 women aged between 16 and 50 years attending 14 general practice surgeries in London over a two-week period in 1990. RESULTS: The response rate was 70%. Over three quarters of the women had heard of emergency contraception; these were mainly women who used contraception, who had higher educational qualifications or who were not Muslim. Women who were the most likely to need and to use emergency contraception--those using barrier methods--had no more accurate knowledge than women using any other method of contraception. Only 53% of barrier method users knew emergency contraception could be used as a backup when other methods failed. Only one fifth of women had heard about this method from their general practitioner or any other health professional, while half had obtained their information from the media. CONCLUSION: These results suggest that including information on emergency contraception in consultations with users of barrier methods of contraception is a small step which general practitioners and practice nurses could take to increase the use of emergency contraception.

Adolescent↗