Biomedical subjects
L Schwartz
Publications and source records attributed to L Schwartz.
Synergy between membrane depolarization and muscarinic receptor activation leads to potentiation of neurotransmitter release (II)
Amplification of muscarinic agonist-induced [3H]noradrenaline ([3H]NE)-release by depolarizing agents, was studied in rat brain cortical slices. [3H]NE basal outflow was enhanced by either K+ (25 mM) or veratridine (2 microM) in a Ca2+-dependent manner and was potentiated beyond additivity in the presence of muscarinic agonists. Facilitation of the [3H]NE-induced release by the simultaneous presence of muscarinic agonists and depolarizing agents is calcium-dependent with a maximal effective concentration of 0.6-0.8 mM. The efficacy of muscarinic agonist to induce basal outflow of [3H]NE is as follows: CCh greater than arecoline greater than oxotremorine M greater than bethanechol greater than pilocarpine, which is similar to their potentiatory effects observed in the presence of depolarizing agents. Potentiation of muscarinic agonist-induced release of [3H]NE by elevated K+ is more pronounced (up to 7-fold) in comparison to potentiation by veratridine (up to 4-fold), irrespective of the various muscarinic agonists. The sequential presence of muscarinic agonists followed by depolarizing agents is not sufficient for eliciting a synergy of [3H]NE outflow, whether receptor activation was initiated prior to depolarization or depolarization was initiated prior to receptor activation. Receptors which do not mediate phosphatidyl inositol (PI) turnover such as nicotine induced [3H]NE-release which is not affected by the presence of depolarizing agents and yielded in their presence additive fractional release only. In this report we establish synergy of [3H]NE release by muscarinic agonists under depolarizing conditions, similar to synergism of inositol phosphate (IP) production which was observed by muscarinic agonists and depolarization agents.(ABSTRACT TRUNCATED AT 250 WORDS)
Percutaneous transluminal angioplasty of stenotic saphenous vein right coronary bypass grafts utilizing a peripheral balloon dilatation catheter without a guiding catheter.
Effective angioplasty of stenosed saphenous vein coronary bypass grafts may be impossible with the standard-size coronary dilatation catheters because the large diameter of these grafts results in unacceptable balloon-to-vessel ratios. We avoided this problem by using a peripheral arterial dilatation catheter with an inflation diameter of 6 mm and obtained a satisfactory short- and long-term result in two patients in whom previous attempts with the largest coronary dilatation catheter (4 mm) had failed. This technique, which precludes the use of a guiding catheter, is suitable only for right bypass grafts.
Don't forget AIDS at any age.
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Two partial remissions induced by an LHRH analogue in two postmenopausal women with metastatic breast cancer.
We report two cases of metastatic breast cancer occurring in two postmenopausal women. Treatment with a luteinizing hormone-releasing hormone (LHRH) analogue, D-TRP6-LHRH, induced partial remission. The blood levels of the follicle stimulating hormone (FSH) and luteinizing hormone (LH) fell sharply under treatment, but the levels of estradiol, estriol, and estrone did not change significantly. We also described the putative mechanisms of action of the LHRH analog.
Randomized trial of chemotherapy versus chemotherapy plus radiotherapy for stage I-II Hodgkin's disease.
A total of 277 patients with untreated Hodgkin's disease, clinical stages I-II, were randomized to cyclophosphamide, vinblastine, procarbazine, and prednisone (CVPP) alone for 6 monthly cycles or to CVPP plus radiation therapy (RT), 3,000 rad, to involved areas (CVPP plus RT). One or more of the following factors were considered as unfavorable prognosis: age greater than 45 years, more than two lymph node areas involved, or bulky disease. In the favorable group, disease-free survival (77% vs. 70%) or overall survival (92% vs. 91%) at 84 months for CVPP versus RT plus CVPP was similar. Patients with unfavorable prognosis treated with RT plus CVPP had longer disease-free survival (75% vs. 34%) (P = .001) and overall survival (84% vs. 66%) than patients treated with CVPP alone.
Aspirin and dipyridamole in the prevention of restenosis after percutaneous transluminal coronary angioplasty.
To examine the role of antiplatelet therapy in the prevention of arterial restenosis after percutaneous transluminal coronary angioplasty (PTCA), we conducted a randomized, double-blind, placebo-controlled study in 376 patients. The active treatment consisted of an oral aspirin-dipyridamole combination (330 mg-75 mg) given three times daily, beginning 24 hours before PTCA. Eight hours before PTCA, the oral dipyridamole was replaced with intravenous dipyridamole at a dosage of 10 mg per hour for 24 hours, and oral aspirin was continued. Sixteen hours after PTCA, the initial combination was reinstituted. Treatment was continued in patients with a successfully dilated vessel until follow-up angiography four to seven months after PTCA--or earlier, if symptoms dictated. Of 249 patients who underwent follow-up angiography, 37.7 percent of patients receiving the active drug had restenosis in at least one segment, as compared with 38.6 percent of patients taking placebo (P not significant). The number of stenotic segments was virtually the same in the two groups. Among the 376 randomized patients, there were 16 periprocedural Q-wave myocardial infarctions--13 in the placebo group and 3 in the active-drug group (6.9 percent vs. 1.6 percent, P = 0.0113). Although the use of this antiplatelet regimen before and after PTCA did not reduce the six-month rate of restenosis after successful coronary angioplasty, it markedly reduced the incidence of transmural myocardial infarction during or soon after PTCA. Thus, the short-term use of antiplatelet agents in relation to PTCA can be recommended.
Treatment of retinoblastoma. Results obtained from a prospective study of 51 patients.
During 4 years, 51 patients with retinoblastoma were studied (unilateral 32, and bilateral 19). Treatment consisted of enucleation of those eyes which showed massive involvement followed by radiotherapy when there was optic nerve and/or orbit involvement. Systemic chemotherapy was administered to all patients who underwent nonsurgical treatment and when the histologic examination showed choroidal optic nerve head and/or optic nerve involvement or residual tumor after enucleation. When there was compromise of the central nervous system intrathecal chemotherapy was administered. Nonsurgical treatment consisted of radiotherapy and/or light coagulation. Survival was 90.6% for unilateral cases and 84.2% for the bilateral. The median follow-up was 31 months and 29 months, respectively. Of 19 conservated eyeballs, 16 preserve useful vision (63%).
An atherosclerosis risk factor assessment program for patients with peripheral arterial occlusive disease.
From a group of 251 high-risk patients less than 65 years of age, 84 with angiographic or vascular laboratory proven peripheral arterial occlusive disease were evaluated in detail. The following risk factors were identified: smoking in 91% with an average of 35 +/- 18 pack/years; treated or untreated hypertension in 40%; hyperlipidemia in 49%; obesity with a body weight greater than 120% of ideal in 18%; diabetes in 9%; family history of premature vascular disease in 70%; and hyperuricemia in 13%. Based on these results, we have introduced a practical approach for investigating and managing risk factors that can be administered by paramedical personnel, utilizing a questionnaire given to patients and standard blood tests to identify important risk factors. The results of the completed questionnaires and blood test are entered on a microcomputer. A program written using d-Base III stores the data, identifies the risk factors and grades their severity. We have designed an information booklet that highlights the individual patient's risk factors and suggests alternatives for management based on the sources of medical and community help available in our area.
Five-year follow-up of Hancock pericardial valves: management of premature failure.
The durability and function of bovine pericardial valves are dependent upon design, preservation, patient factors (age, sex), and site of valve implantation. In 1983, a shelf recall of all Hancock bovine pericardial valves (HPV) was instituted by the manufacturer. This report represents the results of an organized 5-year follow-up in a hospital Prosthetic Valve Registry of 129 HPV implanted in 122 patients (79 males, 43 females) between May 1982 and April 1985 using echo Doppler and careful clinical evaluation. Mean age was 56 +/- 15 years. There were 81 AVR, 33 MVR, 7 DVR, and 1 TVR. Concomitant coronary bypass was performed in 38 patients (31%). Surgery was on a redo basis in 25 patients (20%), urgent in 14 (11%), and for SBE in 8 patients (7%). There were seven hospital deaths (5.7%). Mean follow-up was 44 months (maximum 66 months) for 114 patients (99% complete), representing 417 patient years. There have been 20 late deaths (18%), of which 7 were directly valve related. Linearized frequency of major events (per pt-yr) was: thromboembolism, 1.6%; anticoagulant related hemorrhage, 0.8% (1 late death); prosthetic valve endocarditis 1.3%; primary tissue failure, 5.8%. Patient symptomatology was a more accurate predictor of bioprosthetic failure requiring reoperation than echo Doppler studies, which were completed in 74 of 97 patients examined during scheduled follow-up visits. Twenty-four of the 96 patients (25%) have required re-replacement at a mean interval of 44 months (27-59 months) from initial implantation. This was due to vertical shear starting at the top of the strut anchoring commissural attachments in every case.(ABSTRACT TRUNCATED AT 250 WORDS)
[Evaluation by U.E.R. of health sciences: medicine, pharmacy and odontology].
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Clinical results of pericardial xenograft valves: the Ionescu-Shiley and Hancock valves.
Between 1979 and 1985, 552 Ionescu-Shiley valves were implanted in 511 patients. The Hancock valve was implanted in 122 patients (129 valves) between 1982 and 1983. Sixty percent of procedures were isolated aortic valve replacements. In the Ionescu series, 59% of these were 19 or 21 mm valves while only 15% of the Hancock valves were of this size. For isolated mitral valve replacement, 76% of Ionescu-Shiley valves were 25 to 27 mm, compared to 36% of the Hancock valves. Patient age, sex, prior operations, concomitant surgery (usually coronary bypass), operative mortality and late deaths were similar for both valves. A mean follow-up of 38 months was obtained for each valve population (99% complete) representing a cumulative 1497 patient-years for the Ionescu-Shiley valve and 375.4 patient-years for the Hancock valve. Actuarial survival for the former was 73 +/- 4% at 72 months, and 65 +/- 14% for Hancock valves at 60 months. The frequency of major events during follow-up (thromboembolism, anticoagulant related hemorrhage, bland perivalvular leak and prosthetic valve endocarditis) were similar, but the frequency of primary tissue valve failure was markedly different for the two valves (1.1% per patient-year for Ionescu-Shiley valves and 5.9% for the Hancock valve). The mean interval to replacement of an Ionescu mitral prosthesis was significantly shorter (23.4 months) than for replacement of an aortic prosthesis (42 months) while the mean interval to replacement of an Ionescu aortic and/or a Hancock aortic or mitral were all similar.(ABSTRACT TRUNCATED AT 250 WORDS)
Clinical performance of Bjork-Shiley mechanical heart valves: a perspective on outlet strut fractures in the 60 degrees and 70 degrees convexo-concave disc models.
The convexo-concave disc model of Bjork-Shiley mechanical heart valve is a significant improvement over the spherical disc model and compares favourably to other valves, including bioprostheses, with respect to hemodynamics, thromboembolism, anticoagulant related hemorrhage and prosthetic endocarditis. A small number of the 60 degrees and 70 degrees welded outlet strut Bjork-Shiley convexo-concave valves are at risk of sudden structural failure. The risk is constant or decreasing with time. Elective explanation is not recommended. The integral outlet monostrut 70 degrees Bjork-Shiley convexo-concave valve demonstrates further improvements in design and durability, and is recommended for use in patients who are appropriate candidates for mechanical cardiac prostheses.
Arachidonic acid-induced inflammation: inhibition by dual inhibitor of arachidonic acid metabolism, SK&F 86002.
The antiinflammatory activity of the structurally novel dual inhibitor of arachidonic acid metabolism, SK&F 86002 was evaluated using arachidonic acid-induced edema and inflammatory cell infiltration. Histological examination demonstrated extensive subcutaneous edema and neutrophil (PMN) accumulation in perivascular and interstitial locations one hour after application of arachidonic acid to the ear. SK&F 86002 and, to a lesser extent, phenidone demonstrated potent inhibition of this inflammatory response following oral and topical administration. Nordihydroguaiaretic acid (NDGA) displayed only topical activity. The selective cyclooxygenase inhibitors ibuprofen and naproxen were either inactive or stimulated ear swelling. Histological evaluation of the lesion in drug-treated animals revealed that SK&F 86002 impaired edema formation and caused a significant reduction in numbers of infiltrating neutrophils. Using arachidonic acid-induced peritoneal exudation, a reduction in the cellular infiltrate was observed after oral treatment with SK&F 86002 or phenidone, but not with naproxen. Taken together, these data illustrate the potent antiinflammatory effects of SK&F 86002 and support the suggestion that 5-lipoxygenase products play a significant role in both the edematous and cellular phases of arachidonic acid-induced inflammation.
Complications associated with the guide wire in percutaneous transluminal coronary angioplasty.
This report describes three cases of unraveling of the platinum coil of the guide wire during percutaneous transluminal coronary angioplasty. In one case the wire ruptured and required surgical removal. The exact cause of this phenomenon is not known, but wire entrapment may be a factor. This is more likely to occur with tortuous vessels. Precautions to avoid uncoiling and rupture of guide wires during coronary angioplasty are discussed.
The association of increased levels of intermediate-density lipoproteins with smoking and with coronary artery disease.
Studies were undertaken to determine whether there is an association between elevated levels of intermediate-density lipoproteins (IDL) (Sf 12-60 lipoproteins) and coronary artery disease. Forty-five to sixty-five-year-old men with objectively documented coronary artery disease (n = 58) who were free of known risk factors (diabetes, hypertension, obesity, hyperuricemia, and hypercholesterolemia) were compared with similar men who were free of coronary artery disease (n = 52). Smokers could not be excluded. The coronary artery disease group had a higher rate of cigarette smoking (NS, due to large variations); higher concentrations of triglycerides in their plasma (p = .003) and higher levels of very low-density lipoproteins (VLDL) (p = .007), IDL (p = .016), and low-density lipoproteins (LDL) (p = .04); as well as somewhat lower levels of high-density lipoprotein (HDL) cholesterol (p = .04). Chi-squared analysis demonstrated a strong association between coronary artery disease and IDL apolipoprotein (apo) B (p = .006), coronary artery disease and IDL triglyceride (p = .032), and coronary artery disease and IDL apo B times IDL triglyceride (p = .006) when the top quintile of the population was compared with the bottom quintile for each of these variables. Stepwise logistic regression analysis resulted in rejection of an association between coronary artery disease and HDL cholesterol, plasma triglyceride, VLDL triglyceride, or LDL triglyceride. However, it did show that coronary artery disease was most strongly associated with smoking and that the second strongest association was with IDL.(ABSTRACT TRUNCATED AT 250 WORDS)
The female offender: a Canadian study.
Consecutive female admissions to the Winnipeg Remand Centre were studied and data concerning personal history, family background, psychological factors and mental health were recorded. An effort was made to determine a typical profile of female offenders and relate this to the alleged offences. Our data failed to identify what has been described by others as the "new female criminal".
Vitamin D3 metabolites in amniotic fluid in relation with maternal and fetal sera in term pregnancies.
The concentration of 25-hydroxyvitamin D3 (25(OH)D3), 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were determined in amniotic fluid, fetal cord serum and maternal serum in 26 cases of elective cesarean sections at term. All the women had a normal pregnancy and did not get any vitamin D fortified preparations. The samples were collected during December 1982-April 1983, at 37-40 weeks of pregnancy. The respective levels (+/- S.D.) of 25(OH)D3, 24,25(OH)2D3 and 1,25(OH)2D3 in maternal serum were: 18.03 +/- 10.8 ng/ml, 1.473 +/- 1.562 ng/ml and 36 +/- 21.5 pg/ml; in fetal cord serum: 13.15 +/- 8.3 ng/ml, 0.9 +/- 0.76 ng/ml and 29.2 +/- 18.55 pg/ml and in amniotic fluid: 0.732 +/- 0.508 ng/ml, 0.212 +/- 0.104 ng/ml and 14.3 +/- 10.0 pg/ml. The levels of the three metabolites in maternal and fetal cord serum were not statistically different. There was a statistically significant correlation between maternal and fetal serum levels of 25(OH)D3 and 24,25(OH)2D3 (r = 0.79, p less than 0.01 and r = 0.743, p less than 0.01 respectively). No significant correlation was found in 1,25(OH)2D3 levels between maternal and fetal cord sera. This lack of correlation may well be in agreement with the recent findings of Kouppala, et al. who demonstrated that the fetus contributes to its own pool of 1,25(OH)2D3. A significant difference was found between maternal serum and amniotic fluid levels of the three metabolites. A statistically significant difference was also found between fetal serum levels of 25(OH)D3 and 24,25(OH)2D3 and amniotic fluid levels.(ABSTRACT TRUNCATED AT 250 WORDS)