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Biomedical subjects

R G Williams

Publications and source records attributed to R G Williams.

At least 55 records · Page 3Linked to original sources
PubMed1995

The effects of the nematode peptide, KHEYLRFamide (AF2), on the somatic musculature of the parasitic nematode Ascaris suum.

AF2 is an endogenous RFamide-like peptide from the parasitic nematode Ascaris suum. The potent stimulatory effects of this peptide on the somatic musculature of Ascaris strongly suggest that it may have an important role in the motornervous system. Here we have investigated the possibility that AF2 may elicit a stimulatory action on Ascaris muscle by potentiating the actions of the excitatory cholinergic motonervous system either pre-synaptically, post-synaptically or both. In in vitro pharmacological experiments AF2 produced a dose-dependent increase in the frequency and amplitude of spontaneous contractions of Ascaris muscle strip which lasted for more than 1 h after a 3 min application of AF2 (10 nM-10 microM; N = 7). In addition, AF2 (100 nM) potentiated the contraction elicited by ACh by 43 +/- 9% (P < 0.01; N = 8). In electrophysiological recordings from muscle cells, AF2 (10-100 nM; N = 10) potentiated the amplitude of EJPs (excitatory junction potentials). For 100 nM AF2, the potentiation of the EJP was 218 +/- 48% (N = 7; P < 0.01). This effect reversed after a wash of 10 min. AF2 did not potentiate the depolarization of the muscle cell elicited by bath applied ACh. These latter two observations are consistent with a presynpatic action of AF2. AF2 (10-100 nM) generated spontaneous muscle cell action potentials in previously quiescent cells. This effect took more than 1 h to wash out. These observations are discussed in terms of the paralysis of Ascaris that is elicited by AF2.

Acetylcholine↗
PubMed1995

'Ceruminoma'--a defunct diagnosis.

The clinical and pathological features of glandular tumours of the external auditory meatus are presented. Their heterogenous clinical and pathological features make the collective term 'ceruminoma' ambiguous and misleading. The spectrum of pathological behaviour and histological features demonstrated by these interesting tumours necessitate a broader classification system. In our hospital 32 patients presented with tumours of the external auditory meatus over a 30-year period, of which seven were glandular in origin. A review of the histology of these glandular tumours enabled us to reclassify them as adenoma, cylindroma, adenoid cystic carcinoma or ceruminous adenocarcinoma. Together with the less common mucoepidermoid carcinoma and pleomorphic adenoma this subdivision forms a basis for a more meaningful classification system with prognostic and therapeutic implications specific to each tumour type. The term 'ceruminoma' should no longer be used unqualified.

Adenocarcinoma↗
PubMed1994

Pediatric cardiology in the 1990s.

OBJECTIVES: In 1991, all active board-certified pediatric cardiologists were polled by questionnaire to examine the relation of subspecialty training and motivational and satisfaction issues to practice characteristics. BACKGROUND: Previous questionnaires with regard to manpower status and practice characteristics were published in 1967 and 1980. These indicated a field predominantly centered in academic medicine with growth in manpower close to predicted need. METHODS: The questionnaire was mailed to 844 of 884 active board-certified pediatric cardiologists and was returned anonymously by 570, a 68% response rate. RESULTS: Among respondents, the mean year in which fellowship training was completed was 1974. The average length of subspecialty training was 31 months for all respondents and 34 months among those completing training since 1981. Seventy-seven percent of subspecialty training centered on clinical training. Although there has been a slight increase in research training in recent years, only 18 respondents completed > or = 22 months of research training. Respondents devote a mean of 89% of professional hours to subspecialty activities and spend 63% of total hours in clinical care. Total hours, income and procedures were related to site of professional activity. Professional satisfaction was high in the factors considered more important: professional challenge and interaction, clinical resources, career security and clinical autonomy. CONCLUSIONS: The field of pediatric cardiology is a subspecialty centered on patient care and performance of diagnostic and interventional techniques. Professional activities varied according to practice site. Pediatric cardiologists with basic research training and professional activity remain a minority. Satisfaction is high, with greatest satisfaction in professional interactions and least satisfaction with income and free time.

Cardiology↗
PubMed1994

Conversion of atriopulmonary to cavopulmonary anastomosis in management of late arrhythmias and atrial thrombosis.

The original atriopulmonary connection or "classic" Fontan operation is associated with several late complications such as arrhythmias, right atrial dilatation, and thromboembolism. This report describes our experience with 3 patients who presented with the acute onset of atrial arrhythmias and upon further evaluation were found to have significant hemodynamic lesions. After failing medical management, all 3 patients were treated successfully with surgical conversion of their atriopulmonary connection to a lateral tunnel cavopulmonary Fontan. The postoperative course of these patients was uneventful. However, long-term evaluation is needed to assess the efficacy of this technique in the prevention of postoperative morbidity.

Acute Disease↗
PubMed1994

Acute hemodynamic effects of adjustable atrial septal defect closure in the lateral tunnel Fontan procedure.

OBJECTIVES: This study evaluated the acute hemodynamic changes with atrial septal defect closure in the postoperative period in patients undergoing the Fontan procedure. BACKGROUND: The adjustable atrial septal defect is a modification of the Fontan procedure designed to improve cardiac output and reduce systemic venous hypertension during the postoperative period. Limited information is available on the effects of inter-atrial shunting on the physiology of direct cavopulmonary connection. METHODS: In 11 patients (aged 9 months to 14.5 years), the atrial septal defect was closed 8 h to 4.6 days (mean 1.7 days) postoperatively. Indications for closure included mean right atrial pressure < 15 mm Hg or arterial oxygen saturation < 80%, or both. RESULTS: Data presented are mean values +/- 1 SD. Mean right atrial pressure was 13.4 +/- 3.0 mm Hg on admission to the intensive care unit, 10.0 +/- 2.0 mm Hg (p = 0.02) immediately before closure and 11.4 +/- 2.8 mm Hg (p = 0.02) after closure. There was a significant decrease in cardiac output, as calculated from arteriovenous oxygen saturation difference (26 +/- 9%, p = 0.003), Doppler aortic flow (19 +/- 9%, p = 0.0002) and ventricular volumes by two-dimensional echocardiography (20 +/- 8%, p = 0.0001). Arterial oxygen saturation increased from 82 +/- 5% to 94 +/- 4% (p = 0.0001), and arteriovenous oxygen saturation difference increased from 25 +/- 8% to 33 +/- 9% (p = 0.0001). Systemic oxygen delivery decreased from 727 +/- 354 to 655 +/- 325 ml/min per m2 (p = 0.02). One patient required reopening of the atrial septal defect. CONCLUSIONS: These data demonstrate that a controlled right to left atrial shunt improves cardiac output and systemic oxygen delivery and facilitates the postoperative management of patients after the Fontan procedure. Atrial septal defect closure increases systemic saturation to normal values and prevents potential systemic embolization but significantly decreases oxygen delivery and might limit exercise tolerance.

Adolescent↗
PubMed1994

A nematode FMRFamide-like peptide, SDPNFLRFamide (PF1), relaxes the dorsal muscle strip preparation of Ascaris suum.

PF1 (SDPNFLRFamide) is a FMRFamide-like peptide extracted from the free-living nematode Panagrellus redivivus. Here we show that this peptide causes a hyperpolarization of somatic muscle cells of the parasitic nematode Ascaris suum and a relaxation of the somatic muscle strip preparation. We have assessed whether or not the relaxation of Ascaris dorsal muscle strip by PF1 is due to (i) inhibition of the release of the excitatory neuromuscular junction transmitter acetylcholine (ACh), (ii) potentiation of the release of the inhibitory neuromuscular junction transmitter gamma-aminobutyric acid (GABA) or (iii) a direct inhibitory action of the peptide on the muscle cells. Under the experimental conditions described here, tonic ACh release does not seem to be involved in determining the resting membrane potential or resting tone of the Ascaris dorsal muscle strip and thus inhibition of tonic ACh release is unlikely to explain the relaxation elicited by the peptide. Furthermore, PF1 (100 nM-1 microM) inhibited the contraction of the muscle strip elicited by bath application of ACh, suggesting either a direct inhibitory action of the peptide on the muscle cells or a potentiation of GABA release. In electrophysiological experiments, the reversal potential for the PF1 hyperpolarization was not the same as that for GABA. Thus, PF1 hyperpolarizes Ascaris muscle by a mechanism that does not involve stimulation of GABA release from inhibitory pre-synaptic terminals.

Acetylcholine↗
PubMed1994

Pilot study of the use of the ECFMG clinical competence assessment to provide profiles of clinical competencies of graduates of foreign medical schools for residency directors. Educational Commission for Foreign Medical Graduates.

PURPOSE: To conduct the first of a series of pilot projects of the clinical competence assessment (CCA) of the Educational Commission for Foreign Medical Graduates (ECFMG) in order to provide profiles of clinical competencies of graduates of foreign medical schools for residency directors in the United States and for governments and institutions in other countries. METHOD AND RESULTS: In September 1992 the first pilot project of the ECFMG CCA was conducted for a program director who wanted to evaluate ten first-year residents in a midwestern U.S. program. The CCA consists of integrated clinical encounters with ten standardized patients, 60 laser videodisc pictorials, and analysis of test items of previously completed ECFMG certification examinations. Profiles of the following clinical competencies were provided to the program director: data gathering (history and physical examination), interviewing and interpersonal skills, diagnosis and management skills, interpretation of diagnostic and laboratory procedures, written communication of information to the health care team, and spoken-English proficiency. The profiles were provided as individual scores compared with mean scores of a reference group of 525 first-year residents who took the CCA at four U.S. assessment centers, and as percentile scores with a range of one standard error of measurement. CONCLUSION: The individual performance data in this first pilot project were valuable to the program director, who used them to supplement scores on a written examination during the first residency year. The pilot project has shown the ECFMG CCA to be a useful tool for program directors to evaluate applicants and residents who are graduates of foreign medical schools.

Clinical Competence↗
PubMed1994

Voice changes in acromegaly.

The fundamental frequency of 14 patients undergoing hypophysectomy was studied. Eight patients had acromegaly, 3 had a prolactinoma, and 3 had nonfunctioning adenomas. The fundamental frequency of 22 normal, healthy volunteers was measured for comparison. In addition, the external size of the larynx of all patients and volunteers was measured and a relationship between external laryngeal size and the mean fundamental frequency was identified in the volunteers. The mean fundamental frequency in patients with acromegaly was significantly lower than the other 6 patients undergoing hypophysectomy and, in addition, was also lower than the 22 normal volunteers. Postoperatively the fundamental frequency of the acromegalic patients increased rapidly to within the expected normal range. Patients with acromegaly have a lowered fundamental frequency which is most likely due to altered vocal cord mass and elasticity, which is a reversible change. Patients with acromegaly can expect a rapid and complete return of normal fundamental frequency within 2 weeks of surgery to remove the pituitary adenoma.

Acromegaly↗
PubMed1993

ECFMG assessment of clinical competence of graduates of foreign medical schools. Educational Commission for Foreign Medical Graduates.

OBJECTIVE: To develop an assessment of clinical competence of graduates of foreign medical schools and to determine the reliability and validity of the assessment and the feasibility of large-scale administration. DESIGN: The Educational Commission for Foreign Medical Graduates (ECFMG) clinical competence study included (1) clinical encounters with standardized patients to assess history taking, physical examination, and communication skills; (2) laser videodisk pictorials to assess identification and interpretation of diagnostic procedures; (3) written clinical vignettes to assess diagnosis and management skills; and (4) assessment of spoken English. A uniform method of operating the test centers and of training the standardized patients was developed. SETTING: Medical schools and their primary teaching hospitals and affiliated hospitals. PARTICIPANTS: Six hundred twenty-four first-year residents, of whom 525 are graduates of foreign medical schools. MAIN OUTCOME MEASURES: Scores, reliability coefficients, validity measures, feasibility of multisite administration, trends of scores over time, and acceptability by examinees. RESULTS: The ECFMG clinical competence assessment was conducted at four geographically separate test centers. Reliability coefficients were high (.85) for the integrated clinical encounter and were in a reasonable range (.71 to .82) for all test components. The assessment adds to the predictability of the residents' performance in the hospital over that of current ECFMG certification examinations. Test security was addressed by demonstrating no consistent pattern of change in scores over testing dates. Virtually all examinees thought the assessment was appropriate. Standardized patients were able to assess spoken English accurately. CONCLUSION: The feasibility of conducting a reliable and valid test of clinical competence for graduates of foreign medical schools was demonstrated for this test population.

Clinical Competence↗
PubMed1993

Damus-Stansel-Kaye procedure: current indications and results.

Between October 1983 and August 1991, 29 consecutive Damus-Stansel-Kaye procedures were performed. Indications for operation included restrictive bulboventricular foramen or subaortic stenosis associated with complex univentricular congenital heart disease (25) and Taussig-Bing heart, subaortic stenosis, or both associated with complex biventricular congenital heart disease (4). Twelve patients underwent concurrent Fontan procedures. Average age at operation was 39.8 months (range, 1 to 132 months). Average outflow tract gradient was 28 mm Hg (range, dynamic to 80 mm Hg). Of the 29 patients, 23 were male and 6 were female. There were three early deaths (10%), two in patients who had a concurrent Fontan procedure. Although there was a trend toward lower age and higher outflow tract gradients in nonsurvivors, these and other factors were not statistically significant predictors of death. Actuarial freedom from cardiac-related death was 88% at 5 years (n = 7). In a mean follow-up of 3.5 years (range, 0.1 to 7.7 years), 3 patients have required reoperation (10%), 2 for aortic valve insufficiency (5 days and 2.75 years) and 1 for a gradient across the anastomosis (5.75 years). Actuarial freedom from reoperation related to a failed Damus-Stansel-Kaye procedure was 90% at 4 years and 75% at 6 years (n = 7).

Actuarial Analysis↗
PubMed1993

Technical issues: test application. AAMC.

Eighteen questions are posed that the authors believe address the major technical issues involved in the application of standardized patients (SPs). Following each question, selected empirical evidence and commentary are provided in response to the question and as background for further consideration of the issues. The authors conclude that the evidence from this large and systematic knowledge base about SP examinations is encouraging and should be cause for optimism. Moreover, it is noted that far less is known about the measurement properties of conventional procedures for clinical assessment in medical school courses and clerkships. The collective evidence from this extensive SP research base suggests that medical educators should move ahead to realize the benefits of the high-fidelity standardized approach provided by standardized-patient examinations.

Clinical Clerkship↗
PubMed1993

Use of NBME and USMLE examinations to evaluate medical education programs.

Criteria are presented for determining whether licensure and/or achievement test results should be used as a basis for making various types of comparisons and judgments about medical education programs for program evaluation purposes. United States Medical Licensing Examination (USMLE) examinations and National Board of Medical Examiners (NBME) subject tests are then considered as sources of evaluation data for medical education programs by evaluating these examinations in the light of the proposed criteria. It is concluded that NBME examination and USMLE results may properly be considered one of several tools to use in an evaluation of medical education programs but are not recommended as the sole basis for a judgment of program effectiveness. However, care must be taken to ensure that test score differences are large enough to be real and to have practical significance. Furthermore, changes in curriculum should not be considered or implemented on the basis of NBME/USMLE results unless the changes in test scores are maintained for at least two years. The focus should generally be on inordinately high failure rates rather than on changes in mean class scores. Efforts to develop objective, standardized, and controlled measures of other clinical competencies for national use should be encouraged to minimize the temptation to use USMLE Step 1 and Step 2 scores as the sole basis for comparisons of medical education programs.

Education, Medical, Undergraduate↗
PubMed1993

Echocardiography in the management of single ventricle: fetal through adult life.

Echocardiography contributes to the management of patients with single ventricle by providing an initial comprehensive evaluation in fetal and neonatal life. This allows planning of the initial surgical palliation, usually without the need for cardiac catheterization. Serial surveillance for problems such as subaortic stenosis, valvar insufficiency, or complications of the mitral palliation aids in planning for the timing and type of subsequent surgical procedures. Evaluation of single ventricle size, shape, and mass provides some indication of risk for a Fontan procedure. Transesophageal echocardiography provides an excellent window for the evaluation of the interatrial baffle for shunts, thrombi, or occlusion in the early postoperative period. Later, studies of ventricular and valve function help to direct medical management such as afterload reduction and diuretic therapy.

Echocardiography↗