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[This corrects the article DOI: 10.1371/journal.pone.0136486.].
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Interest in the welfare of cattle in the beef industry has intensified over time because of ethical concerns and varying societal perceptions that exist about the treatment and living conditions of farm animals. The definition of welfare will vary according to an individual's philosophies (how one defines and prioritizes what is "good"), experiences (societal and cultural influences of animal roles and relationships), and involvement in the livestock industry (knowledge of how livestock operations work and why). Many welfare concerns in the beef industry could be mitigated by enhancing traditional husbandry practices that utilize practical improvements to alleviate or eliminate heat stress, pain from routine husbandry procedures, negative cattle handling, and the transitional effects of weaning, dry feeding, transportation, and comingling of calves. Recent concerns about the potential welfare effects of feeding technologies such as ß-adrenergic agonists (BAA) have emerged and led to industry-wide effects, including the removal of a single BAA product from the market and the development of BAA-specific welfare audits. Altogether, the beef industry continues to be challenged by welfare issues that question a large range of practices, from traditional husbandry to newer technological advancements. As welfare awareness increases, efforts to improve livestock care and management must focus on scientific investigations, practical solutions, consumer perceptions, and educational tools that advance knowledge and training in livestock welfare. Furthermore, the future of beef cattle welfare must align welfare concerns with other aspects of sustainable beef production such as environmental quality, profitability, food safety, and nutritional quality.
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Criação de Animais Domésticos/métodos , Criação de Animais Domésticos/tendências , Bem-Estar do Animal/normas , Bovinos , Carne , Criação de Animais Domésticos/economia , Bem-Estar do Animal/ética , Animais , Inocuidade dos Alimentos/métodos , Tempo (Meteorologia)RESUMO
The UCNA collaboration is making a precision measurement of the ß asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be Ì Îµ=0.9985(4).
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BACKGROUND: Somatization is a common, costly problem with great morbidity, but there has been no effective screening method to identify these patients and target them for treatment. OBJECTIVES: We tested a hypothesis that we could identify high utilizing somatizing patients from a management information system (MIS) by total number of visits and what we termed "somatization potential," the percentage of visits for which ICD-9 primary diagnosis codes represented disorders in the musculoskeletal, nervous, or gastrointestinal systems or ill-defined complaints. METHODS: We identified 883 high users from the MIS of a large staff model HMO as those having six or more visits during the year studied (65th percentile). A physician rater, without knowledge of hypotheses and predictors, then reviewed the medical records of these patients and identified somatizing patients (n = 122) and nonsomatizing patients (n = 761). In two-thirds of the population (the derivation set), we used logistic regression to refine our hypothesis and identify predictors of somatization available from the MIS: demographic data, all medical encounters, and primary diagnoses made by usual care physicians (ICD-9 codes). We then tested our prediction model in the remaining one-third of the population (the validation set) to validate its usefulness. RESULTS: The derivation set contained the following significant correlates of somatization: gender, total number of visits, and percent of visits with somatization potential. The c-statistic, equivalent to the area under the ROC curve, was 0.90. In the validation set, the explanatory power was less with a still impressive c-statistic of 0.78. A predicted probability of 0.04 identified almost all somatizers, whereas a predicted probability of 0.40 identified about half of all somatizers but produced few false positives. CONCLUSIONS: We have developed and validated a prediction model from the MIS that helps to distinguish chronic somatizing patients from other high utilizing patients. Our method requires corroboration but carries the promise of providing clinicians and health plan directors with an inexpensive, simple approach for identifying the common somatizing patient and, in turn, targeting them for treatment. The screener does not require clinicians' time.
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Sistemas Pré-Pagos de Saúde/estatística & dados numéricos , Sistemas de Informação Administrativa , Prontuários Médicos , Transtornos Somatoformes/diagnóstico , Transtornos Somatoformes/epidemiologia , Revisão da Utilização de Recursos de Saúde/métodos , Adulto , Doença Crônica/epidemiologia , Feminino , Gastroenteropatias/epidemiologia , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Doenças Musculoesqueléticas/epidemiologia , Doenças do Sistema Nervoso/epidemiologia , Visita a Consultório Médico/estatística & dados numéricos , Sensibilidade e Especificidade , Estados Unidos/epidemiologiaRESUMO
In a rare study of effectiveness of an interviewing method, we previously reported a randomized controlled trial demonstrating that training in a step-by-step patient-centered interviewing method improved residents' knowledge, attitudes, and skills and had a consistently positive effect on trained residents' patients. For those who wish to use this evidence-based patient-centered method as a template for their own teaching, we describe here for the first time our training program--and propose that the training can be adapted for students, physicians, nurse practitioners, physician assistants, and other new learners as well. Training was skills-oriented and experiential, fostered positive attitudes towards patient-centered interviewing, and used a learner-centered approach which paid special attention to the teacher-resident relationship and to the resident's self-awareness. Skills training was guided by a newly identified patient-centered interviewing method that described the step-by-step use of specific behaviors.
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Educação de Pós-Graduação em Medicina/métodos , Medicina Baseada em Evidências/organização & administração , Entrevistas como Assunto/métodos , Assistência Centrada no Paciente/organização & administração , Relações Médico-Paciente , Ensino/métodos , Atitude do Pessoal de Saúde , Competência Clínica , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Internato e Residência , Avaliação de Programas e Projetos de SaúdeRESUMO
Survival of Trichomonas gallinae was examined in white-winged dove (Zenaida asiatica) carcasses to assess whether birds that have been dead up to 8 hr can be sampled reliably for this protozoan. Carcasses of 100 T. gallinae-positive white-winged doves were separated into four groups of 25 birds, representing 2, 4, 6, and 8 hr post mortem sampling intervals and placed into an environmental chamber maintained at 27 C and 75% relative humidity. Live T. gallinae were isolated in 96, 100, 100, and 92% of the carcasses at each of the respective post mortem intervals. The experiment was repeated with another 100 carcasses of T. gallinae-positive white-winged doves placed in the environmental chamber, this time maintained at 27 C and 40% relative humidity. Live T. gallinae occurred in 96, 100, 96, and 100% of the carcasses at each of the respective post mortem intervals. Across both trials, the overall ability to detect positive birds from sampling carcasses up to 8 hrs post mortem was 97%. An a posteriori experiment was conducted in which 23 and 18 carcasses from the second trial were maintained in the environmental chamber at 27 C and 40% relative humidity and resampled at 24 and 48 hr post mortem, respectively. Live trichomonads were isolated from 91 and 44% of the carcasses at 24 and 48 hr, respectively. Results suggest live T. gallinae can be obtained from dove carcasses reliably up to 8 hr and possibly up to 24 hr after host death. The ability for T. gallinae to survive within this time interval can aid wildlife personnel in monitoring this protozoan at hunter check stations or obtaining samples from recently killed birds.
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Doenças das Aves/parasitologia , Columbidae/parasitologia , Tricomoníase/veterinária , Trichomonas/isolamento & purificação , Animais , Doenças das Aves/diagnóstico , Cadáver , Fatores de Tempo , Trichomonas/fisiologia , Tricomoníase/diagnóstico , Tricomoníase/parasitologiaRESUMO
Transbilayer phospholipid asymmetry is a common structural feature of most biological membranes. This organization of lipids is generated and maintained by a number of phospholipid transporters that vary in lipid specificity, energy requirements and direction of transport. These transporters can be divided into three classes: (1) bidirectional, non-energy dependent 'scramblases', and energy-dependent transporters that move lipids (2) toward ('flippases') or (3) away from ('floppases') the cytofacial surface of the membrane. One of the more elusive members of this family is the plasma membrane aminophospholipid flippase, which selectively transports phosphatidylserine from the external to the cytofacial monolayer of the plasma membrane. This review summarizes the characteristics of aminophospholipid flippase activity in intact cells and describes current strategies to identify and isolate this protein. The biochemical characteristics of candidate flippases are critically compared and their potential role in flippase activity is evaluated.
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Proteínas de Transporte/química , Membrana Celular/metabolismo , Bicamadas Lipídicas/química , Proteínas de Membrana/química , Proteínas de Transferência de Fosfolipídeos , Animais , Transporte Biológico , ATPase de Ca(2+) e Mg(2+)/metabolismo , Proteínas de Transporte/isolamento & purificação , Proteínas de Transporte/metabolismo , Linhagem Celular , Membrana Celular/enzimologia , Grânulos Cromafim/enzimologia , Membrana Eritrocítica/enzimologia , Humanos , Proteínas de Membrana/isolamento & purificação , Proteínas de Membrana/metabolismo , Nucleotidases/metabolismo , Fosfatidilserinas/metabolismo , Especificidade por SubstratoRESUMO
PURPOSE: To evaluate the effect of intensive attitudinal training on residents' learning the patient-centered interviewing skills required to establish a healthy provider-patient relationship and to communicate effectively. METHOD: While teaching 53 residents patient-centered interviewing skills, the authors also trained them to recognize previously unrecognized, negative attitudes that interfered with learning the skills. The authors, using an iterative, consensus-building process based on the residents' performances and personality data, identified a spectrum of responses to the educational intervention. Barriers to and facilitators of mastery of skills were analyzed and this information was used to help residents overcome skill deficits. RESULTS: To varying degrees, 44 residents became aware of previously unrecognized attitudes to the extent that they improved their patient-centered interviewing skills. Six residents failed to develop awareness of negative attitudes and showed little learning and clinical use of the interviewing skills being taught. Three residents who rapidly developed superb interviewing skills showed no negative attitude towards using them. CONCLUSIONS: Pending a confirmatory hypothesis-testing study, the authors believe that, as residents learn how to conduct patient-centered interviews, training in awareness of interfering attitudes should accompany training in skills.
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Atitude do Pessoal de Saúde , Medicina de Família e Comunidade/educação , Internato e Residência , Entrevistas como Assunto , Assistência Centrada no Paciente/métodos , Relações Médico-Paciente , Competência Clínica , Feminino , Humanos , MasculinoRESUMO
BACKGROUND: Interviewing and the physician-patient relationship are crucial elements of medical care, but residencies provide little formal instruction in these areas. OBJECTIVE: To determine the effects of a training program in interviewing on 1) residents' attitudes toward and skills in interviewing and 2) patients' physical and psychosocial well-being and satisfaction with care. DESIGN: Randomized, controlled study. SETTING: Two university-based primary care residencies. PARTICIPANTS: 63 primary care residents in postgraduate year 1. INTERVENTION: A 1-month, full-time rotation in interviewing and related psychosocial topics. MEASUREMENTS: Residents and their patients were assessed before and after the 1-month rotation. Questionnaires were used to assess residents' commitment to interviewing and psychosocial medicine, estimate of the importance of such care, and confidence in their ability to provide such care. Knowledge of interviewing and psychosocial medicine was assessed with a multiple-choice test. Audiotaped interviews with real patients and videotaped interviews with simulated patients were rated for specific interviewing behaviors. Patients' anxiety, depression, and social dysfunction; role limitations; somatic symptom status; and levels of satisfaction with medical visits were assessed by questionnaires and telephone interviews. RESULTS: Trained residents were superior to untrained residents in knowledge (difference in adjusted post-test mean scores, 15.7% [95% CI, 11% to 20%]); attitudes, such as confidence in psychological sensitivity (difference, 0.61 points on a 7-point scale [CI, 0.32 to 0.91 points]); somatization management (difference, 0.99 points [CI, 0.64 to 1.35 points]); interviewing of real patients (difference, 1.39 points on an 11-point scale [CI, 0.32 to 2.45 points]); and interviewing (data gathering) of simulated patients (difference, 2.67 points [CI, 1.77 to 3.56 points]). Mean differences between the study groups were consistently in the appropriate direction for patient satisfaction and patient well-being, but effect sizes were too small to be considered meaningful. CONCLUSION: An intensive 1-month training rotation in interviewing improved residents' knowledge about, attitudes toward, and skills in interviewing.
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Competência Clínica , Medicina de Família e Comunidade/educação , Internato e Residência , Entrevistas como Assunto , Atitude do Pessoal de Saúde , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Satisfação do Paciente , Relações Médico-Paciente , Inquéritos e QuestionáriosRESUMO
PURPOSE: To use a controlled, randomized design to assess the effect on patient satisfaction of an intensive psychosocial training program for residents. METHOD: Twenty-six first-year residents, in two internal medicine and family practice community-based programs affiliated with the Michigan State University College of Human Medicine, were randomly assigned during 1991 and 1992 to a control group or a one-month intensive training program. Experiential teaching focused on many psychosocial skills required in primary care. A 29-item questionnaire administered before and after the residents' training evaluated their patients' satisfaction regarding patient disclosure, physician empathy, confidence in physician, general satisfaction, and comparison of the physician with other physicians. Analyses of covariance with groups and gender as factors and pre-training patient satisfaction scores as the covariate evaluated the effect of the training. RESULTS: The patients of the trained residents expressed more confidence in their physicians (p = .01) and more general satisfaction (p = .02) than did the patients of controls. The effect of training on patient satisfaction with patient disclosure (p < .01) and physician empathy (p < .05) was greater for female than for male residents. CONCLUSION: The intensive psychosocial training program for residents improved their patients' satisfaction.
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Internato e Residência , Satisfação do Paciente , Relações Médico-Paciente , Psicologia/educação , Competência Clínica , Medicina de Família e Comunidade/educação , Feminino , Humanos , Medicina Interna/educação , Entrevistas como Assunto , Masculino , Michigan , Educação de Pacientes como Assunto , Autoimagem , Fatores Sexuais , Ensino/métodosRESUMO
OBJECTIVE: To evaluate an intensive training program's effects on residents' confidence in their ability in, anticipation of positive outcomes from, and personal commitment to psychosocial behaviors. DESIGN: Controlled randomized study. SETTING: A university- and community-based primary care residency training program. PARTICIPANTS: 26 first-year residents in internal medicine and family practice. INTERVENTION: The residents were randomly assigned to a control group or to one-month intensive training centered on psychosocial skills needed in primary care. MEASUREMENTS: Questionnaires measuring knowledge of psychosocial medicine, and self-confidence in, anticipation of positive outcomes from, and personal commitment to five skill areas: psychological sensitivity, emotional sensitivity, management of somatization, and directive and nondirective facilitation of patient communication. RESULTS: The trained residents expressed higher self-confidence in all five areas of psychosocial skill (p < 0.03 for all tests), anticipated more positive outcomes for emotional sensitivity (p = 0.05), managing somatization (p = 0.03), and nondirectively facilitating patient communication (p = 0.02), and were more strongly committed to being emotionally sensitive (p = 0.055) and managing somatization (p = 0.056), compared with the untrained residents. The trained residents also evidenced more knowledge of psychosocial medicine than did the untrained residents (p < 0.001). CONCLUSIONS: Intensive psychosocial training improves residents' self-confidence in their ability regarding key psychosocial behaviors and increases their knowledge of psychosocial medicine. Training also increases anticipation of positive outcomes from and personal commitment to some, but not all, psychosocial skills.
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Medicina Interna/educação , Internato e Residência , Relações Médico-Paciente , Médicos de Família/educação , Competência Clínica , Feminino , Humanos , Masculino , Médicos de Família/psicologia , Programas de Autoavaliação , Inquéritos e QuestionáriosRESUMO
Regulation of the neural cell adhesion molecule (NCAM) was examined in primary cultures of chick skeletal muscle grown in serum-free defined medium. Relative levels of NCAM (per microgram protein) increased 20-30% in myotubes grown on Matrigel, a reconstituted basement membrane preparation, compared to those grown on collagen; total NCAM levels on Matrigel were increased 40-55% due to the additional increase in total protein. A dose dependent increase in relative NCAM levels in myotubes grown on Matrigel in defined medium was observed with the addition of adsorbed horse serum, while relative NCAM levels in myotubes grown on collagen were unaffected by altering the serum concentration. Thus, extracellular matrix molecules and soluble factors exert trophic effects on myotube NCAM expression. Similar developmental changes in the expression of the different molecular size forms of NCAM occurred in myotubes grown on collagen and Matrigel: levels of 150K and 135K Mr forms decreased during development, while 125K remained prominent in older myotubes. Relative NCAM levels were specifically enhanced 11-26% by several factors: nerve growth factor, thyroxine, insulin-like growth factor II, dibutyryl cyclic AMP, veratridine (a sodium ion channel agonist), and nisoldipine (a calcium ion channel agonist). Total protein and overall myotube development in serum-free cultures were enhanced by fetuin, insulin-like growth factor II, acidic fibroblast growth factor, calcitonin gene-related peptide, dibutyryl cyclic AMP, and veratridine. Thus, changes in extracellular matrix, intracellular calcium, and sodium ions, as well as extracellular trophic factors, such as nerve growth factor, thyroxine, and insulin-like growth factor II, may regulate muscle NCAM expression during embryonic development.
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Moléculas de Adesão Celular Neuronais/metabolismo , Substâncias de Crescimento/fisiologia , Músculos/metabolismo , Acetilcolinesterase/metabolismo , Animais , Cálcio/metabolismo , Cálcio/farmacologia , Moléculas de Adesão Celular Neuronais/química , Células Cultivadas , Embrião de Galinha , Meios de Cultura , AMP Cíclico/farmacologia , GMP Cíclico/farmacologia , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Desenvolvimento Muscular , Músculos/citologia , Sistemas do Segundo Mensageiro/efeitos dos fármacos , Sódio/metabolismo , Sódio/farmacologiaAssuntos
ATPase de Ca(2+) e Mg(2+)/sangue , Proteínas de Transporte/sangue , Eritrócitos/enzimologia , Proteínas de Membrana/sangue , Fosfatidilserinas/sangue , Proteínas de Transferência de Fosfolipídeos , Transporte Biológico , ATPase de Ca(2+) e Mg(2+)/isolamento & purificação , Proteínas de Transporte/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Humanos , Cinética , Proteínas de Membrana/isolamento & purificação , Peso MolecularRESUMO
This study prospectively tested the hypothesis that patients with periodic limb movement disorder (PLMD) have longer motor conduction latencies than normals. Six healthy adults, 13 patients with PLMD, and 8 patients with long-term multiple sclerosis (MS) had recordings of motor conduction latencies during wake and sleep. MS subjects were included only to show that we could detect prolongation of central conduction; nonMS subjects were used to test the hypothesis. Subjects had no other medical or sleep problems. A novel magnetic stimulator, the Cadwell MES-10, was discharged over the vertex and the C7 cervical spine. It triggered compound muscle action potentials that were recorded in the abductor digiti minimi in the hand. The conduction latencies were the total conduction time (TCT), measured vertex to hand, and the peripheral conduction time (PCT), measured C7 to hand. The difference was the central conduction time (CCT). Only TCT could be obtained during sleep. Supporting the use of TCT as an indirect measure of central conduction was that, in all waking subjects, TCT correlated with CCT (r = 0.91, p = 0.001) but not with PCT. Reliabilities during wake and sleep were 0.95 or higher for TCT and PCT measurements. Waking CCT was greater in MS subjects (13.77 milliseconds) than those without MS (9.21 milliseconds), p = 0.001. Sleeping TCT was much less impressive in distinguishing MS subjects [27.08 milliseconds in nonrapid eye movement (NREM) sleep; 28.64 milliseconds in rapid eye movement (REM) sleep] from nonMS subjects (24.45 milliseconds in NREM; 24.84 milliseconds for REM), p = 0.07 for NREM and p = 0.04 for REM.(ABSTRACT TRUNCATED AT 250 WORDS)
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Magnetismo , Transtornos dos Movimentos/fisiopatologia , Músculos/fisiopatologia , Adulto , Feminino , Humanos , Perna (Membro)/fisiopatologia , Masculino , Pessoa de Meia-Idade , Periodicidade , Tempo de Reação/fisiologia , Sono/fisiologiaRESUMO
Previously reported serum-free defined media for muscle cell culture require supplementation with hormones, purified growth factors or attachment factors. This report describes a culture system that enhances embryonic chick, skeletal muscle cell growth and differentiation in a serum-free defined medium, without added specialized trophic factors. Myoblasts adhered more to and proliferated more rapidly on a reconstituted basement membrane substrate, Matrigel, than on rat-tail collagen. Matrigel contains several basement membrane attachment molecules which apparently obviate the need for added purified attachment factors. Matrigel also appeared to play a trophic role in subsequent development by enabling the serum-free growth of myotubes which suggests that Matrigel mediates the cellular interaction of growth or attachment factors. Collagen, on the other hand, did not support serum-free myotube growth. Supplementation of defined medium with increasing levels of horse serum enhanced total protein in myotubes grown on both substrates; protein was higher in Matrigel cultures for each medium tested. The serum-free defined medium supported complete morphological differentiation of myotubes grown on Matrigel and maintained myotube cultures up to 22 days. Fibroblast proliferation was higher in cultures on collagen in defined medium with high serum levels, but was virtually eliminated in cultures on Matrigel in serum-free defined medium. The culture system described supports the differentiation of embryonic muscle cells in a simple, serum-free defined medium, thus providing an in vitro model of developing myotubes which should be particularly useful for studies of regulation mediated by extracellular factors.
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Colágeno/farmacologia , Laminina/farmacologia , Microtúbulos/efeitos dos fármacos , Músculos/metabolismo , Proteoglicanas/farmacologia , Animais , Divisão Celular/fisiologia , Embrião de Galinha , Meios de Cultura , DNA/biossíntese , Combinação de Medicamentos , Fibroblastos/efeitos dos fármacos , Músculos/citologia , Músculos/ultraestruturaRESUMO
STUDY OBJECTIVE: To determine the efficacy of a comprehensive, one-month psychosocial training program for first-year medical residents. DESIGN: Nonrandomized, controlled study with immediate pre/post evaluation. Limited evaluation of some residents was also conducted an average of 15 months after teaching. SETTING: Community-based, primary care-oriented residency program at Michigan State University (MSU). SUBJECTS: All 28 interns from the single-track MSU residency program during 1986/87-88/89 participated in this required rotation; there was no dropout or instance of noncompliance with the study. In the follow-up study in 1989, all 13 available trainees participated. Of 20 untrained, volunteer controls, ten were second/third-year residents in the same program during 1986/87 and ten were interns from a similar MSU program in Kalamazoo, MI, during 1988/89. TEACHING INTERVENTION: An experiential, skill-oriented, and learner-centered rotation with competency-based objects focused on communication and relationship-building skills and on the diagnosis and management of psychologically disturbed medical patients. MEASUREMENTS AND MAIN RESULTS: The two subsets of the control group were combined because residents and training programs were similar and because means and standard deviations for the subsets were similar on all measures. By two-way analyses of variance (group x gender), the trainee group showed significantly greater gains (p less than 0.001) on questionnaires addressing knowledge, self-assessment, and attitudes; a mean of 15 months following training, there was no significant deterioration of attitude scores. All trainees were also able to identify previously unrecognized, potentially deleterious personal responses using a systematic rating procedure. Residents' acceptance of the program was high. CONCLUSIONS: Intensive, comprehensive psychosocial training was well accepted by residents. It improved their knowledge, self-awareness, self-assessment, and attitudes, the latter improvement persisting well beyond training.
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Competência Clínica , Medicina Interna/educação , Internato e Residência , Entrevista Psicológica/métodos , Relações Médico-Paciente , Adulto , Atitude do Pessoal de Saúde , Currículo , Feminino , Humanos , Masculino , Encaminhamento e Consulta , Programas de Autoavaliação , Ensino/métodosRESUMO
Neural cell adhesion molecule (NCAM) has been described as a family of membrane glycoproteins. However, soluble NCAM immunoreactivity has long been recognized. We here show that soluble NCAM is composed of two quantitatively major polypeptides of Mr 180,000 and 115,000 and two minor components of Mr 160,000 and 145,000. Soluble NCAM was immunochemically identical to membrane NCAM, was polysialylated and carried the HNK-1 epitope. It only constituted 0.8% of total NCAM in newborn rat brain. Soluble NCAM appeared in neuronal cell culture medium 15-30 min after the start of synthesis preceding accumulation of membrane-associated NCAM on the cell surface. This indicates that soluble NCAM contains a secreted component.
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Antígenos de Superfície/análise , Química Encefálica , Animais , Animais Recém-Nascidos/metabolismo , Anticorpos Monoclonais/análise , Antígenos de Superfície/genética , Antígenos de Superfície/imunologia , Adesão Celular , Moléculas de Adesão Celular , Membrana Celular/análise , Células Cultivadas , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Epitopos/análise , Técnicas de Imunoadsorção , Neurônios/metabolismo , RNA Mensageiro/análise , Ratos , Ácidos Siálicos/análise , SolubilidadeRESUMO
Glucose 6-phosphate dehydrogenase (G6PDH) activity was examined in the developing embryonic chick in brachial and lumbar spinal cord and pectoral and leg muscle. Enzyme activity was generally highest at the earliest stage examined, embryonic day 5. The developmental profiles for G6PDH activity in the two muscles were similar: a sharp initial decrease occurred between days 5 and 9, with relatively low levels present by day 18; peaks of G6PDH activity at days 12 and 16 were more prominent in leg muscle. Similar levels of G6PDH were also detected in spinal cord with the developmental profile in the brachial spinal cord resembling that seen in muscle. In lumbar spinal cord, initial G6PDH activity was lower than in brachial spinal cord; the developmental profile, however, resembled that seen in the brachial spinal cord, with an initial drop in enzyme activity seen between days 5 and 7. Neural regulation of G6PDH activity in mature muscle is believed to repress enzyme synthesis. The drop in G6PDH activity observed in embryonic spinal cord and muscle between days 5 and 9 coincides with the initiation of functional neuromuscular contacts. Hence, the normal regulation of G6PDH during embryonic development may involve the repression of G6PDH in spinal cord neurons and muscle, possibly effected by their interaction.
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Glucosefosfato Desidrogenase/metabolismo , Músculos/embriologia , Medula Espinal/embriologia , Animais , Embrião de Galinha , Citosol/enzimologia , Desenvolvimento Embrionário e Fetal , Cinética , Músculos/enzimologia , Medula Espinal/enzimologiaRESUMO
The biosynthesis of the neural cell adhesion molecule (N-CAM) was studied in primary cultures of rat cerebral glial cells, cerebellar granule neurons, and skeletal muscle cells. The three cell types produced different N-CAM polypeptide patterns. Glial cells synthesized a 135,000 Mr polypeptide B and a 115,000 Mr polypeptide C, whereas neurons expressed a 200,000 Mr polypeptide A as well as polypeptide B. Skeletal muscle cells produced polypeptide B. The polypeptides synthesized by the three cell types were immunochemically identical. The membrane association of polypeptide C was investigated with methods that distinguish peripheral and integral membrane proteins. Polypeptide C was found to be a peripheral membrane protein, whereas polypeptides A and B were integral membrane proteins with cytoplasmic domains of approximately 50,000 and approximately 25,000 Mr, respectively. The affinity of the membrane binding of polypeptide C increased during postnatal development. The posttranslational modifications of polypeptide C were investigated in glial cell cultures, and it was found to be N-linked glycosylated and sulfated.
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Antígenos de Superfície/biossíntese , Adesão Celular , Glicoproteínas/biossíntese , Proteínas de Membrana/biossíntese , Fatores Etários , Animais , Astrócitos/metabolismo , Moléculas de Adesão Celular , Células Cultivadas , Cerebelo/metabolismo , Citoplasma/metabolismo , Substâncias Macromoleculares , Peso Molecular , Músculos/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Ratos , Sulfatos/metabolismo , Tunicamicina/farmacologiaRESUMO
The joining together of neurites to form fascicles and the growth of axons along glial surfaces during early development suggest that neurone-neurone and neurone-glial adhesion interactions are of considerable importance for defining nerve tracts. In vitro studies have indicated that adhesion between neurones involves a glycoprotein that has been independently studied under the names of N-CAM (for neural cell adhesion molecule), D2-CAM and BSP-2 (refs 10, 11). As N-CAM/D2-CAM appears to be a homophilic ligand that binds to N-CAM/D2-CAM polypeptide on adjacent cells, this glycoprotein is potentially important in adhesion interactions between any two N-CAM/D2-CAM-expressing cells. While it has been suggested that neurone-glial adhesion involves molecules other than N-CAM/D2-CAM, it is known that N-CAM/D2-CAM antigenic determinants are expressed by glial cells in vivo and that injection of anti-N-CAM antibodies into the eye-cup of chick embryos disrupts normal patterns of neuritic apposition to glial endfeet in the developing optic stalk. Do the molecules expressed by glia share restricted antigenic determinants, or binding domains, with N-CAM/D2-CAM, or are N-CAM/D2-CAM polypeptides expressed by glia? Here we present immunocytochemical evidence which suggests that all classes of macroglia express N-CAM/D2-CAM antigenic determinants on their surfaces and immunochemical analyses which indicate that the molecules expressed by purified astrocytes are closely similar, or identical, to at least some forms of N-CAM/D2-CAM obtained from whole brain or purified neurones. However, our results also suggest that different N-CAM/D2-CAM polypeptides may be separately expressed by neurones and astrocytes.