PubMed Health⌕ Search

Biomedical subjects

A Rothman

Publications and source records attributed to A Rothman.

At least 73 records · Page 4Linked to original sources
PubMed1994

Studies on the effect of ethanol on the Na+, and the Na+, K(+)-ATPase activities of plasma membranes of rat kidney proximal tubular cells.

In the present work it was investigated the effect of 2% ethanol on the Na+ and on the Na+, K(+)-ATPase activities. The differential effect of the alcohol on the two ATPases (approximately 40% inhibition of the Na(+)-ATPase and approximately 10% inhibition of the Na+, K(+)-ATPase), is not due to a higher degree of denaturalization of the enzyme, nor to a faster effect of ethanol on the Na(+)-than on the Na+, K(+)-ATPase. Our results show that ethanol affects the selectivity of the Na+, K(+)-ATPase for Na+ and/or for K+, enhancing the Na+ affinity for the K+ sites, and/or reducing the K+ affinity for its own sites. This effect was not seen for the Na(+)-ATPase, indicating that 2% ethanol inhibits the two ATPases in a totally different way.

Animals↗
PubMed1993

Contralateral femoral vein removal of a circumferentially ruptured balloon-catheter following pulmonary artery angioplasty.

While attempting to remove a circumferentially ruptured balloon following branch pulmonary artery angioplasty, the shaft of the catheter broke, leaving the distal portion of the balloon and catheter in the femoral vein but still on the exchange wire. We describe a method to retrieve the broken balloon catheter via the contralateral femoral vein.

Angioplasty, Balloon↗
PubMed1993

The ethics objective structured clinical examination.

OBJECTIVE: To develop objective structured clinical examination (OSCE) stations to assess the ability of physicians to address selected clinical-ethical situations, and to evaluate inter-rater agreement in these stations. DESIGN: Two ten-minute OSCE stations were developed using video-taped encounters between attending physicians and standardized patients. One scenario involved a daughter requesting a do-not-resuscitate (DNR) order for her competent mother without the mother's knowledge; the other involved a competent elderly woman requesting not to be re-intubated if her congestive heart failure worsened. The scenarios were evaluated using foreign medical graduates taking an OSCE. Each candidate was scored on his or her interaction with a standardized patient in the two OSCE stations by two independent observers. PARTICIPANTS: Eight attending physicians from the Division of General Internal Medicine at the Toronto Hospital were used to develop the OSCE stations, and 69 foreign medical graduates taking the University of Toronto Pre-Internship Program OSCE were used to evaluate the stations. RESULTS: The inter-rater reliability coefficients for the DNR and intubation scenarios were 0.79 (95% CI 0.69-0.87) and 0.75 (95% CI 0.62-0.84), respectively. For the DNR station, the scores of the two examiners, on a scale of 0 to 10, agreed exactly for 34 candidates (50%), within one mark for 59 candidates (87%), and within two marks for 65 candidates (96%). For the intubation station, the scores of the two examiners agreed exactly for 27 candidates (40%), within one mark for 56 candidates (84%), and within two marks for 63 candidates (94%). CONCLUSIONS: The authors produced ethics OSCE stations with face and content validity and satisfactory inter-rater agreement. Ethics OSCE stations may be suitable for evaluating the ability of medical students and residents to address selected clinical-ethical situations.

Analysis of Variance↗
PubMed1993

Percutaneous coil embolization of superfluous vascular connections in patients with congenital heart disease.

Transcatheter Gianturco coil embolization of 26 superfluous but hemodynamically significant vascular connections was attempted in 19 patients with congenital heart disease. There were 18 aortopulmonary collaterals, two vessels involved in pulmonary sequestration, two surgical aortopulmonary shunts (one inadvertently connected from the left subclavian artery to a left upper pulmonary vein), two cases of patent ductus arteriosus, one regurgitant left ventricular-to-descending aorta conduit, and a left superior vena cava-to-left atrium post Fontan procedure. The mean ratio of coil to vessel diameter was 1.6 +/- 0.7, and a mean of 1.5 +/- 1.1 coils were used per vessel. Occlusion was achieved in 24 of 26 attempts (92%), being complete in 21 (81%) and near complete (> 80% decrease in flow) in three (12%). Two attempts failed; a tortuous aortopulmonary collateral was engaged by the delivery catheter but the coil could not be advanced past an acute angle, and another aortopulmonary collateral had a narrow origin and enlarged distally, resulting in coil migration to a distal pulmonary artery branch. One patient had a transient decrease in leg pulses that resolved spontaneously. Fever occurred in four patients (21%) within 12 hours of coil placement, and resolved in all without sequelae or complications. A variety of undesirable vascular connections in patients with congenital heart disease can be safely and effectively treated by percutaneous coil embolization.

Aorta↗
PubMed1993

Guidelines for estimating the real cost of an objective structured clinical examination.

A major impediment to the use of the objective structured clinical examination (OSCE) is that it is a labor-intensive and costly form of assessment. The cost of an OSCE is highly dependent on the particular model used, the extent to which hidden costs are reported, and the purpose of the examination. The authors detail hypothetical costs of running a four-hour OSCE for 120 medical students at one medical school. Costs are reported for four phases of this process: development, production, administration, and post-examination reporting and analysis. Costs are reported at two ends of the spectrum: the high end, where it is assumed that little is paid for by the institution and that faculty receive honoraria for work put into the examination; and the low end, where it is assumed that the sponsoring institution defrays basic costs and that faculty do not receive honoraria for their participation. The total costs reported for a first-time examination were $104,400 and $59,460 (Canadian dollars) at the high and low ends, respectively. These translate to per-student costs of $870 and $496. The cost of running an OSCE is high. However, the OSCE is uniquely capable of assessing many fundamental clinical skills that are presently not being assessed in a rigorous way in most medical schools.

Canada↗
PubMed1992

Effect of ethanol on the Na(+)- and the Na+,K(+)-ATPase activities of basolateral plasma membranes of kidney proximal tubular cells.

The Na(+)- and the Na+,K(+)-ATPase activities of basolateral plasma membranes from rat kidney proximal tubular cells were affected differentially by ethanol. Moreover, at concentrations of ethanol that can be reached in vivo in the blood plasma (50 mM) there was a significant effect on the Na(+)-ATPase activity and practically no effect on the Na+,K(+)-ATPase activity.

Adenosine Triphosphatases↗
PubMed1992

An objective structured clinical examination for the licentiate: report of the pilot project of the Medical Council of Canada.

The Medical Council of Canada (MCC) administers a qualifying examination for the issuance of a license to practice medicine. To date, this examination does not test the clinical skills of history taking, physical examination, and communication. The MCC is implementing an objective structured clinical examination (OSCE) to test these skills in October 1992. A pilot examination was developed to test the feasibility, reliability, and validity of running a multisite, two-form, four-hour, 20-station OSCE for national licensure. In February 1991, 240 volunteer first- and second-year residents were tested at four sites. The candidates were randomly assigned to one of two forms of the test and one of two sites for two of the four sites. Generalizability analysis revealed that the variance due to form was 0.0 and that due to site was .16 compared with a total variance of 280.86. The reliabilities (inter-station) were .56 and .60 for the two forms. Station total-test score correlations, used to measure station validity, were significant for 38 of the 40 stations used (range .14-.60). The results of the OSCE correlated moderately with the MCC qualifying examination; these correlations were .32 and .35 for the two test forms. Content validity was assessed by postexamination questionnaires given to the physician examiners using a scale of 0 (low) to 10 (high). The physicians' mean ratings were: importance of the stations, 8.1 (SD, 1.8); success of the examination in testing core skills, 8.1 (SD, 1.6); and degree of challenge, 7.8 (SD, 2.1). The results indicate that a full-scale national administration of an OSCE for licensure is feasible using the model developed. Aspects of validity have been established and strategies to augment reliability have been developed.

Canada↗
PubMed1992

Intraluminal ultrasound imaging through a balloon dilation catheter in an animal model of coarctation of the aorta.

BACKGROUND: Controversy still exists over the optimal balloon size, extent of vascular disruption, and long-term results of balloon dilation therapy for coarctation of the aorta. Intravascular ultrasound imaging has been used in patients with coronary artery disease to provide further insight into the anatomy of atherosclerotic lesions and the results of angioplasty and atherectomy. Initial observations of the results of balloon dilation of coarctations with intravascular ultrasound imaging have shown prominent dissections of the inner vascular layers that are often not detected by angiography. The purpose of this study was to test a new transballoon catheter ultrasonic imaging system capable of on-line direct visualization of lumen diameter and vessel wall structure for imaging before, during, and after dilation in an acute animal model of aortic coarctation. METHODS AND RESULTS: Abdominal aortic coarctations were created surgically in three 14-19-kg mongrel dogs by using Teflon gauze ties. The 6.8F ultrasound balloon catheter was placed percutaneously in the right femoral artery through a 9F sheath. Ultrasound imaging allowed measurement of the coarctation diameter, characterization of the vessel wall structure, localization of the stenosis, and placement of the midportion of the balloon at the narrowest area. Imaging through the balloon was performed through several dilations (five to eight per animal), and after balloon deflation, it provided information on postdilation diameter, intimal tears, long-segment dissections, and intramural thrombi, findings that were confirmed at postmortem examination. CONCLUSIONS: The results of this study demonstrate that imaging with a new intraballoon ultrasound device is feasible during inflation to therapeutic dilation pressures; it allows visualization of the changes in diameter and vascular wall structure after serial dilations without having to recross the obstructed area. Adaptation to larger balloon sizes and lower frequencies should make this system applicable to interventional catheterizations in patients with congenital cardiac and vascular lesions.

Animals↗
PubMed1992

Transesophageal echocardiography in infants and children with congenital heart disease.

TEE applications for children and infants with congenital heart disease are now clinically established and TEE is being used in most major pediatric cardiovascular centers. This technology has evolved to the point that it is capable of providing diagnostic quality imaging, even for small infants. With expanding technology and increasing experience, new and more sophisticated applications will be found for pediatric TEE.

Child↗
PubMed1992

Development and characterization of a cloned rat pulmonary arterial smooth muscle cell line that maintains differentiated properties through multiple subcultures.

BACKGROUND: Pulmonary hypertension is associated with abnormal pulmonary arterial contractility and growth. The mechanisms for these abnormalities are largely unknown. To study these processes, we sought to develop an in vitro system. Even though cultured aortic and pulmonary artery smooth muscle cells (SMCs) have been of considerable value in studying smooth muscle biology, one drawback of this system has been that these cells often lose differentiated properties in an unpredictable manner when they are passaged in culture. In addition, there appear to be significant differences in physiological and pathological responses between the systemic and pulmonary circulations, many of which could be directly related to the smooth muscle. We therefore established a cloned population of rat pulmonary arterial SMCs (PASMCs) that maintain differentiated properties through multiple subcultures. METHODS AND RESULTS: PASMCs were obtained initially by enzymatic dissociation from pulmonary arteries of adult Sprague-Dawley rats. From these cells, clones were isolated. The cloned cells retained expression of functional surface receptors for angiotensin II, norepinephrine, and alpha-thrombin and high levels of the smooth muscle isoforms of alpha-actin, myosin heavy chain, myosin regulatory light chain, and alpha-tropomyosin mRNAs even after multiple passages. The cells could also be transfected and processed exogenous transcripts in a smooth muscle-specific fashion. CONCLUSIONS: These cloned PASMCs retain many differentiated characteristics and should be valuable for future studies of pulmonary vascular smooth muscle cell biology.

Animals↗
PubMed1991

Stretch increases inositol trisphosphate and inositol tetrakisphosphate in cultured pulmonary vascular smooth muscle cells.

There are no reports of the effect of stretch on inositol phosphates in smooth muscle. Phosphoinositide and inositol phosphate metabolism was studied in cultured rat vascular smooth muscle cells subjected to stretching. The masses of inositol trisphosphate and tetrakisphosphate increased (+34 +/- 7% and +58 +/- 12%, respectively; p less than 0.001) after 25 s of a single 20% stretch and had returned to control levels by 45 s; phosphatidylinositol, phosphatidylinositol phosphate and bisphosphate did not change. Repetitive stretch did not alter the masses of any of the compounds. A single stretch also increased 45Ca2+ efflux (+52 +/- 5%, p less than 0.01). These data suggest that stretch of cultured vascular smooth muscle can elicit a rapid, short-lived increase in inositol phosphates, which may subsequently affect Ca2+.

Animals↗
PubMed1990

Ruptured arteriovenous malformation complicating thrombolytic therapy with tissue plasminogen activator.

It is though that the clot-specific activity of tissue plasminogen activator, used in the treatment of acute myocardial infarction, makes bleeding complications less common than does the use of either streptokinase or urokinase. The incidence of intracerebral hemorrhage complicating the use of tissue plasminogen activator has been estimated to be 0.68%. This is a report of the rupture of an intracranial arteriovenous malformation complicating the use of tissue plasminogen activator therapy. Theories for the mechanism of hemorrhage in this instance are presented, as are suggestions for future use of the enzyme.

Aged↗
PubMed1990

Early results and follow-up of balloon angioplasty for branch pulmonary artery stenoses.

Two hundred eighteen balloon angioplasty procedures were performed in 135 patients with branch pulmonary artery stenoses from June 1984 to February 1989. Arteries were dilated in patients with tetralogy of Fallot (n = 49), tetralogy of Fallot/pulmonary atresia (n = 64), isolated peripheral pulmonary artery stenoses (n = 58) and "other" lesions (the majority had truncus arteriosus or single ventricle and surgically induced pulmonary artery stenoses (n = 47). Mean age at dilation was 6.6 +/- 6.3 years (range 1 month to 38.5 years). The mean diameter of the lesion increased from 3.8 +/- 1.7 to 5.5 +/- 2.1 mm with dilation (p = 0.001). The overall success rate was 58% (127 of 218 dilations), assessed by the following criteria: an increase greater than or equal to 50% of predilation diameter, an increase greater than 20% in flow to the affected lung or a decrease greater than 20% in systolic right ventricular to aortic pressure ratio. Success did not correlate with patient age. Mean balloon to artery ratio was higher in successful (4.2) than in failed (3.0) angioplasty procedures (p = 0.0001). There were four early deaths: two of the patients had pulmonary artery rupture with angioplasty performed less than 1 month after pulmonary artery surgery. An aneurysm occurred in 11 arteries and transient pulmonary edema in four patients. At angiography performed a mean of 10 months (range 1 to 54) after dilation, the mean diameter of 57 arteries was unchanged (5.5 versus 5.4 mm). However, 5 of 32 initially successfully dilated vessels had returned to predilation size as a result of restenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗