Search PubMed⌕ Search

Biomedical subjects

R G Williams

Publications and source records attributed to R G Williams.

At least 109 records · Page 6Linked to original sources
PubMed1987

Direct, standardized assessment of clinical competence.

Doctor ratings of clerkship performance are often discounted as not accurately reflecting clinical competence. Such ratings are influenced by the following uncontrolled variables: case difficulty; differing rater focus and standards; lack of agreement on what constitutes acceptable performance; and collective patient care responsibility masks individual contributions. Standardized direct measures of clinical competence were developed to control these factors and allow direct comparisons of student performance. Students saw 18 patients representing frequently occurring and important patient problems. Student actions and decisions were recorded and subsequent responses to questions revealed knowledge of pathophysiology, basis for actions, use and interpretation of laboratory investigations, and management. Actions and responses were graded using a pre-set key. The examination covered 73% of designated clinical competencies. Examinations scores corresponded with independent measures of clinical competence. Reliability studies indicated that new cases can be substituted in subsequent years with confidence that scores will maintain similar meaning. Costs are +6.95 per student per case, which is modest considering the quality and quantity of information acquired. Methods described are practical for evaluation of clerks and residents and for licensing and specialty certification examinations.

Clinical Clerkship↗
PubMed1987

Congenital abnormalities of the aortic arch: MR imaging.

Thirty-four patients, 1 month to 63 years old, with known or suspected congenital abnormalities of the aortic arch underwent magnetic resonance (MR) imaging. Sixteen patients were studied retrospectively, 18 prospectively. In all retrospective studies, the aortic arch abnormality was seen with MR imaging. In the prospective studies, MR imaging enabled diagnosis in 15 of 18 (83%) patients. Twenty-nine of 34 patients underwent two-dimensional echocardiography; nine were studied retrospectively, 20 prospectively. In the prospective studies, echocardiography enabled diagnosis in 13 of 20 (65%) patients. Although two-dimensional echocardiography has a high sensitivity in the detection of aortic arch abnormalities in the neonate, arch abnormalities in the neonate, its sensitivity is lower in older children, adults, and postoperative patients. The authors' experience shows that MR imaging is an important, noninvasive modality in the evaluation of older children, adults, and postoperative patients with congenital aortic arch abnormalities.

Adolescent↗
PubMed1986

Balloon and blade atrial septostomy facilitated by two-dimensional echocardiography.

Two-dimensional echocardiography (2-D echo) was used as an imaging device for the performance of balloon atrial septostomy (n = 25) and blade atrial septostomy (n = 3). Biplane fluoroscopy with 2-D echo or 2-D echo alone were used in the cardiac catheterization laboratory to place the balloon or blade septostomy catheter in the left atrium. Echocardiography confirmed the position of the septostomy catheter before pullback. Balloon inflation and balloon or blade pullback to the right atrium was performed with 2-D echocardiographic visualization. In 8 critically ill newborn infants, balloon atrial septostomy was done in the neonatal intensive care unit without flouroscopy. The safety and efficacy of 2-D echo to assist balloon or blade atrial septostomy in the catheterization laboratory or as the sole imaging device in the neonatal intensive care unit are confirmed. Use of the subcostal 4-chamber and sagittal views to image cardiac anatomy and catheter position during the procedure are emphasized. Two-dimensional echo is particularly helpful in cases of cardiac malposition and during transseptal puncture of the atrial septum before blade septostomy, and lowers radiation dose when used in conjunction with fluoroscopy.

Cardiac Catheterization↗
PubMed1986

Subaortic obstruction in complex congenital heart disease: management by proximal pulmonary artery to ascending aorta end to side anastomosis.

Six patients with univentricular heart and one patient with d-transposition of the great arteries had transection of the main pulmonary artery with an end to side anastomosis of the main pulmonary artery to the ascending aorta to relieve subaortic obstruction. Two operations were performed as a palliative procedure within the first 6 months of life and five were performed as part of a definitive repair (four modified Fontan procedures and one repair of transposition of the great arteries with ventricular septal defect). There was one surgical death (14%) occurring 1 day postoperatively from low cardiac output. The remaining six patients are doing well 1 to 19 months postoperatively (mean 11.4 months). The proximal pulmonary artery to ascending aorta end to side anastomosis is an effective means of bypassing subaortic obstruction associated with complex congenital heart disease.

Aorta↗
PubMed1985

Physicians' fees.

Explore the source record for details and available documents.

Fees, Medical↗
PubMed1985

Accuracy of prospective two-dimensional echocardiographic evaluation of left ventricular outflow tract in complete transposition of the great arteries.

Thirty-two consecutive infants with transposition of the great arteries (TGA) and ventricular septal defect underwent subxiphoid 2-dimensional echocardiography (2-D echo). Two independent observers prospectively evaluated each echocardiogram for the presence or absence of left ventricular (LV) outflow tract obstruction, whether outflow obstruction was dynamic or fixed, or both, and the precise anatomic type of fixed obstruction. Compared with the LV-to-pulmonary artery gradient determined at cardiac catheterization, 2-D echo yielded low false-negative (7 to 13%) and false-positive (0 to 6%) rates for diagnosing the presence or absence of LV outflow tract obstruction. Moreover, the false-negative cases were only minor errors, because the measured LV-pulmonary artery gradients proved to be less than 25 mm Hg. Compared with the long-axial oblique LV angiogram, 2-D echo yielded no false-negative results in detection of outflow tract obstruction, which was at least partly fixed. Compared with autopsy/surgical observation, 2-D echo made no significant errors in delineating the exact anatomic type of fixed obstruction. The diagnostic accuracy of 2-D echo in detecting and characterizing LV outflow tract obstruction limits the need for "routine" cardiac catheterization before repair in infants with TGA and intact ventricular septum. Furthermore, because certain types of fixed LV outflow tract obstruction are difficult for the surgeon to visualize and alleviate, precise knowledge of the anatomic type of fixed obstruction influences the choice among Rastelli, intraatrial baffle and arterial switch procedures in patients with TGA and ventricular septal defect.

Cardiac Catheterization↗
PubMed1985

Echocardiography in the neonate and young infant.

The neonate and young child present unique problems in echocardiographic diagnosis because of the wide spectrum of possible abnormalities and the tendency toward multiple lesions, requiring clear visualization of all great veins and arteries as well as intracardiac structures. Performance and interpretation of echocardiograms in this age group require an extensive knowledge of the pathologic anatomy of congenital heart disease. Recognition of unusual lesions is facilitated by displaying the heart in an anatomically familiar (upright) format in order to draw from experience in angiography and pathology. The subxiphoid (subcostal) transducer position provides a flexible acoustic window for scanning the heart and great vessels in a multitude of planes, providing a general orientation for each cardiac segment. All other transducer positions are utilized to provide specific anatomic information. Although in this age group echocardiographic visualization of intracardiac anatomy is superior to other techniques, delineation of the great vessels remains its greatest limitation. Tortuous vessels may not lie in a single plane and, therefore, cannot always be displayed throughout its length by a "slice" technique such as echocardiography. In addition, limited focal range of most high frequency transducers is a continuing impediment to imaging structures in the posterior and superior mediastinum. Echocardiography provides a cost-effective means for identifying the neonate with life-threatening cardiovascular disease. It provides a complete and definitive anatomic diagnosis, in some cases eliminating the need for further procedures, while in others, improving the timing and performance of cardiac catheterization. Future studies should investigate the proper utilization of echocardiography as adjunct to or replacement of other techniques in the management of the young child.

Angiography↗
PubMed1985

Cholecystokinin and gastrin forms in the nervous system.

Cholecystokinin octapeptide is the predominant representative of the gastrin-CCK family in the central nervous system. Other forms occur in low concentrations, or restricted locations, as do the gastrins. The pathways of biosynthetic processing can now be studied in detail, following the elucidation of the cDNA sequence for the two peptides. In the vagus both CCK and gastrin can be found. Brain stem neurons receiving an input from gastric mechanoreceptors respond to CCK-8, but most do not respond to gastrin given intravenously or intra-arterially. This system, which may well be involved in mediating the peripheral satiety effect of CCK, is therefore able to distinguish between the two peptides.

Amino Acid Sequence↗
PubMed1985

Morphological and electrophysiological determination of the projections of jaw-elevator muscle spindle afferents in rats.

The fluorescent compound Lucifer Yellow was injected into the somata of nine identified jaw-elevator muscle spindle afferents, located in the V mesencephalic nucleus. Reconstructions of the central course of their axons were subsequently made from serial, transverse, sections to identify sites of projection. Three sites of termination were identified on the basis of collaterals that ended in varicosities and/or boutons. All afferents projected to the V nucleus oralis and, all but one, also to the V motor nucleus. Two out of nine afferents had terminations in the supra-trigeminal nucleus, though a further four appeared to send collaterals to this area. The relative density of projection, judged by the number of collaterals supplied to each area, decreased in the order: V nucleus oralis, V motor nucleus and supra-trigeminal nucleus. The central course of the afferent axons was such that impulses from the periphery would arrive first at the V motor nucleus, then the V nucleus oralis, the supra-trigeminal nucleus, and finally the afferent somata in the V mesencephalic nucleus. In animals in which the masseter nerve was exposed in-continuity for electrical stimulation, electrophysiological recordings were made in the three areas described above to identify units that received a monosynaptic input from spindles in the masseter muscle. Criteria were formulated on the basis of the pattern of responses on stimulation of the masseter nerve, and the morphology of labelled neurones, for differentiating between afferents, interneurones, and motoneurones. In the V motor nucleus, monosynaptic excitatory post-synaptic potentials (e.p.s.p.s) were obtained in both synergist and masseter motoneurones. These were assumed to arise from a masseter muscle spindle input as the thresholds for exciting such afferents and eliciting e.p.s.p.s were similar. Some interneurones, chiefly in the V nucleus oralis, were activated at thresholds close to that of muscle spindle afferents and could also fire in response to muscle stretch. As their latencies (measured extracellularly) were similar to that of e.p.s.p.s in motoneurones, they were assumed to receive a monosynaptic muscle spindle input. However, most interneurones were activated at longer latencies (up to 7 ms) and some also fired to muscle stretch. Arguments are advanced, based on the long rise time of e.p.s.p.s recorded in some, that the majority of these may also be candidates for monosynaptic activation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Early and late results in the treatment of patients with pulmonary atresia and intact ventricular septum.

The courses of 22 consecutive patients with pulmonary atresia and intact ventricular septum who underwent surgery between 1977 and 1984 were reviewed. This included 18 patients undergoing an initial surgical palliation, and four patients referred for a definitive procedure. A surgically oriented classification based on the degree of right ventricular hypoplasia was developed and applied. Three groups were identified and were termed the mild, moderate, and severe hypoplasia groups. Those in the mild and moderate groups had mild or moderate right ventricular and tricuspid hypoplasia with well-developed right ventricular outflow tracts and were therefore acceptable candidates for procedures to create an opening between the right ventricle and pulmonary artery. Those in the severe hypoplasia group and severe hypoplasia of the tricuspid valve, the right ventricle, and the right ventricle outflow tract so that attempts at establishing continuity with the pulmonary artery were thought to be unlikely to succeed. There were three patients with mild, 11 with moderate, and eight with severe hypoplasia. In the mild hypoplasia group, all three patients initially underwent valvotomy alone, but two required a shunt in the early postoperative period. In the moderate hypoplasia group, all patients underwent a valvotomy and received a central shunt with a snare, which allowed subsequent adjustment of pulmonary flow without thoracotomy in four patients. In the severe hypoplasia group, five patients received a shunt alone and one underwent valvotomy with atrial septectomy. This last patient represents the only early (less than 30 days) death in the series (6% mortality).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Vessel Prosthesis↗
PubMed1984

Evidence for different patterns of post-translational processing of pro-enkephalin in the bovine adrenal, colon and striatum indicated by radioimmunoassay using region-specific antisera to Met-Enk-Arg6-Phe7 and Met-Enk-Arg6-Gly7-Leu8.

Specific antisera to two opioid peptides, Met-Enk-Arg6-Phe7 and Met-Enk-Arg6-Gly7-Leu8, were used in radioimmunoassay to study molecular forms in extracts of bovine adrenal, striatum and colon. The antisera to Met-Enk-Arg6-Phe7 and Met-Enk-Arg6-Gly7-Leu8 were each highly specific for the C-terminus of their respective haptens and showed less than 1% cross-reactivity with related enkephalins and their variants. In adrenal extracts, gel filtration on Sephadex G-50 indicated N-terminally extended forms of Met-Enk-Arg6-Phe7 and Met-Enk-Arg6-Gly7-Leu8 as the predominating immunoreactive species, whereas in the striatum and colon the main immunoreactive forms were compatible with the hepta- and octapeptides. The results suggest different patterns of post-translational processing of precursors in the adrenal medulla compared with striatal and colonic neurones.

Adrenal Glands↗
PubMed1984

Moyamoya disease and cerebral hemorrhage.

A case with the clinical, x-ray, and computed tomographic features characteristic of moyamoya disease and a large intracerebral hemorrhage is presented. The recent literature is reviewed, noting current concepts in diagnosis, treatment, and prognosis of this curious disorder. Although much has been written about moyamoya disease and its treatment, it remains a very unusual disorder, particularly in a middle-aged white adult.

Arterial Occlusive Diseases↗
PubMed1984

Cancer of the mouth in an isolated community--the results of treatment.

A survey is presented of all known cases of cancer of the mouth in a population of nearly half a million in a relatively isolated part of Yorkshire, with the results of treatment of squamous carcinoma, adeno-carcinoma, lympho-sarcoma, malignant tumours of odontogenic origin and sarcomas.

Adenocarcinoma↗