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Biomedical subjects

R Michels

Publications and source records attributed to R Michels.

13 recordsLinked to original sources
PubMed1991

Effects of electric and magnetic transcranial stimulation on long latency reflexes.

The interaction of transcranial electric and magnetic brain stimulation with electrically elicited short- and long latency reflexes (LLR) of hand and forearm flexor muscles has been investigated in normal subjects. In the first paradigm, the motor potential evoked in thenar muscles by transcranial stimulation was conditioned by median nerve stimulation at various conditioning-test intervals. At short intervals (electric: 5-12.5 ms, magnetic: 0-7.5 ms) facilitation occurred that corresponded to the H-reflex and at longer intervals (electric: 25-40 ms, magnetic: 22.5-35 ms) there was a facilitation corresponding to the LLR. Electric and magnetic stimulation resulted in a similar degree of facilitation. A second paradigm investigated the facilitation of the forearm flexor H-reflex by a cutaneo-muscular LLR elicited by radial superficial nerve stimulation and transcranial stimulation used separately or together. When electric and magnetic brain stimulation were compared, magnetic brain stimulation was followed by significant extrafacilitation but electric stimulation was not. This result favours an interaction between the afferent volley eliciting the LLR and transcranial magnetic stimulation most likely at supraspinal level.

Adult↗
PubMed1991

Sequence analysis of the ARG7 gene of Schizosaccharomyces pombe coding for argininosuccinate lyase. Expression of the gene in Saccharomyces cerevisiae.

The complete nucleotide sequence of the ARG7 gene, coding for argininosuccinate lyase (EC 4.3.2.1), in the fission yeast (Schizosaccharomyces pombe) has been determined. It consists of an open reading frame of 461 codons. The deduced protein has a molecular weight of 51,200 Da. The gene is devoid of introns which is confirmed by the fact that it is expressed in Escherichia coli after spontaneous insertion of a bacterial sequence probably bearing a prokaryotic promoter. A perfect "TATA" box is found at -72 and the major transcription initiation site in Saccharomyces cerevisiae is located at -11 as shown by primer extension experiments. Comparison of the S. pombe lyase with related proteins from other organisms reveals an important degree of conservation except in the carboxyterminal part of the polypeptide. Additionally, a deletion removing 66 amino acids of the carboxy terminus yields an enzyme exhibiting some biological activity. A unique 1,500 b transcript was found in S. cerevisiae when the intact gene was present, but the deleted version of the gene gave rise to at least three transcripts of 1,800, 2,800 and 3,900 b.

Amino Acid Sequence↗
PubMed1991

Coronary angioplasty via saphenous vein grafts.

Percutaneous transluminal angioplasty of coronary stenoses distal to anastomosis of a venous graft was attempted through the graft 22 times in 19 patients. Ten patients had stable angina, seven unstable angina and two patients acute myocardial infarction. The mean interval between bypass surgery and angioplasty was 6.5 years (range 1-15). Fifteen lesions were dilated in the left anterior descending artery, five in the right coronary artery, and two in the circumflex artery. Three procedures were for double lesions. In two cases, a stenosed vein graft was also dilated. All grafts were cannulated with an El Gamal guiding catheter. The procedure failed in two cases. The remaining 20 lesions were successfully dilated. Early and late occlusion of the graft occurred in one patient, and coronary arterial stenosis recurred in two patients. All three patients underwent successful redilatation. The 17 patients undergoing successful dilatation were asymptomatic, with a normal exercise test and/or maintained angiographic result at follow-up of 14 months mean duration (range 2-48). Angioplasty of coronary stenosis through a vein graft is feasible, safe and effective. This therapeutic approach avoids the need for repeat bypass surgery and, as judged by long-term follow-up, has a favourable clinical outcome.

Angina Pectoris↗
PubMed1990

Value of immediate angioplasty after intravenous streptokinase in acute myocardial infarction.

To improve reperfusion, immediate percutaneous transluminal coronary angioplasty (PTCA) was considered after intravenous streptokinase (0.75 to 1.5 million U) was administered to 98 patients with acute myocardial infarction less than 4 hours after the onset of chest pain. Thirty-four culprit arteries were occluded (group A); 42 arteries were patent with residual stenosis of more than 70% (group B). Twenty-two patients had residual stenosis of less than 70% (group C); eight of these had severe disease of the remaining vessels. Group C patients were either treated conservatively or underwent bypass surgery. Immediate PTCA was attempted in 74 patients (32 in group A, 42 in group B) and was successful in 68 (92%). Emergency bypass surgery for acute occlusion after PTCA was required in two patients. Follow-up averaged 23 months (range, 16 to 47 months). Asymptomatic occlusion recurred in three patients. Restenosis occurred in five patients: four had early restenosis (one in group A, three in group B) and one had late restenosis (group B). These arteries were successfully redilated. Late reinfarction occurred in two patients. They were treated with intravenous urokinase and repeat PTCA. Elective bypass surgery was performed in three patients because of recurrent angina. They had severe three-vessel disease as revealed by control angiography. The mortality rate was 2.7% (two patients; one in group B had early reinfarction, and one patient in group A died suddenly after 17 months). Eighty-five percent of patients treated with PTCA alone remain free of symptoms. This approach has a high success rate and low morbidity and mortality rates. Long-term results are superior to thrombolysis alone.

Angioplasty, Balloon, Coronary↗
PubMed1990

The future of psychiatry.

Psychiatry is rapidly changing. The authors review the history of psychiatry in the United States, its gradual integration into medicine and society, and the dialectic between its "biologic" and "mentalist" outlooks. After describing the current state of the profession and its knowledge base, they discuss the likely future of the field: psychiatry's projected mode of practice and economics; its future as a science for understanding human behavior; its expected boundaries with other treatment disciplines; its anticipated relationship with academia and with the community at large; and internal issues for the profession. Unprecedented internal and external pressures on the field are likely to require important reconceptualizations of psychiatry both by its members and by the rest of the American public.

Forecasting↗
PubMed1989

Bilateral mammary artery surgery or percutaneous transluminal coronary angioplasty for multivessel coronary artery disease? An analysis of effects and costs.

Seventy-two patients with stable or unstable angina treated since 1983 by multivessel-PTCA(MVP) were retrospectively compared with 44 similar patients that were suitable for MVP, but who had undergone bilateral mammary artery (BIMA) surgery (and additional vein grafts in 60.5% of the patients) since 1986. Both groups were comparable (P = not significant [NS]) for gender, age, most risk factors, objective ischaemia and left ventricular function; however, in the BIMA group there were more previous infarctions (P = 0.02), hypertension (P = 0.03), three-vessel disease (P = 0.0001), and less severe angina (P = 0.007). In the BIMA group, a mean of 3.1 (range 2-5) vessels were treated and in the MVP group 2.0 (range 2-3) vessels (P = 0.0001). Both groups were almost completely revascularized (NS). In 39.5% of the BIMA group, no veins were used and in 20.9% the BIMAs were used as sequential grafts. In-hospital mortality was comparable: 2.3% for BIMA and 1.4% for MVP, so were periprocedural infarctions (13.6% vs 8.3%), rethoracotomies (9.1% vs 0%), emergency procedures (0% vs 5.7%), low cardiac output (2.3% vs 5.6%) and other complications (18.2% vs 9.2%). The mean stay (days) on the ICU/CCU for BIMA was 2.3 and for MVP 1.6 (P = 0.005) and the mean hospital stay for BIMA 12.3 and for MVP 6.6 (P = 0.0001). The maximum and mean follow-up (months) of 43 BIMA and 71 MVP hospital survivors was 35 vs 72 and 9.5 vs 22.3 (P = 0.0001) with a late mortality of 0% and 4.2% (NS). MVP patients, including 12 with re-procedures, had more recurrent angina (17.7% vs 4.7%, P less than 0.05) and more often used anti-anginal medications (62.0% vs 18.6%, P less than 0.0001). Late complications (excluding re-procedures) were comparable for MVP and BIMA (20% vs 9.3%, 4.4% vs 0%, 9.2% vs 14%). MVP patients had more re-hospitalizations (34 vs 5, P less than 0.0001), re-catheterizations (33% vs 2.3%, P less than 0.0001) and cardiac re-procedures (16 vs 0, P = 0.0006) than BIMA patients. Recurrent-angina-free survival at 1 year was 96% after BIMA and 64% after MVP (P less than 0.01). Event-free survival at 1 year was 86% after BIMA and 58% after MVP (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1979

Intra-aortic balloon pumping in coronary artery disease.

Cardiogenic shock and severe left ventricular failure after acute myocardial infarction, refractory angina pectoris at rest either of new onset or superimposed on stable angina pectoris, or occurring in the post infarct (less than 2 weeks) period, and the suspicion of a slowly evolving infarction are the main indications for intra-aortic balloon pumping at the Thoraxcenter. 76 patients were treated with intra-aortic balloon pumping for cardiogenic shock after acute myocardial infarction and left ventricular failure, 42/76 (55%) could be weaned, 9 (12%) died within 3 months, 33 (43%) survived over 3 months, to date 29 are alive. 42 patients with refractory angina at rest were treated with intra-aortic balloon pumping. Pain relief was prompt in 41 (98%), who subsequently underwent coronary artery bypass grafting. Total myocardial infarction rate was 11% (5/42), total mortality rate was 7%. Perioperative myocardial infarction rate was 8% (4/42) and perioperative mortality was 7% (3/42). Pain relief was prompt in 14/17 patients (82%) with post infarct refractory angina. In 3 patients pain persisted despite intra-aortic balloon pumping, all sustained a myocardial infarction, 1 died, 2 other patients were excluded for surgery. 12 patients underwent coronary artery bypass grafting, none died, none developed acute myocardial infarction, 3 have mild stable angina. In 8 patients a slowly evolving myocardial infarction was suspected. Pain relief was prompt in 7/8 (88%) after institution of intra-aortic balloon pumping. Intra-aortic balloon pumping improves prognosis in cardiogenic shock after myocardial infarction, and abolishes refractory ischemic pain.

Adult↗
PubMed1975

A clinical clerkship in psychiatry.

A clinical clerkship was organized around the goal of teaching information and skills that would be needed by the nonpsychiatrist physician. In most clinical clerkships the students work on an inpatient service. In the clerkship described here the setting is an outpatient clinic, which provides a more relevant experience. Videotaped psychiatric interviews are used extensively and have been found to provide a valuable teaching format. They are effective in holding student interest, in avoiding the practical difficulties of live interviews, and in teaching active listening and interviewing technique, as well as in demonstrating a variety of psychopathology. Field trips to state psychiatric hospitals, institutions for mental defectives, clinics for treating alcoholics or addicts, and other mental health facilities have been used but have not been found to be a very valuable part of the program.

Education, Medical, Undergraduate↗