Search PubMed⌕ Search

Biomedical subjects

L Schwartz

Publications and source records attributed to L Schwartz.

At least 181 records · Page 10Linked to original sources
PubMed1987

Mortality of workers in styrene-butadiene polymer production.

A total of 13,920 males who had worked in eight styrene-butadiene rubber polymer manufacturing plants in the US and Canada for at least 1 year were followed for deaths from 1943 when the industry began to 1979. Mortality ratios standardized for age, race, and calendar time using US male rates as a comparison revealed no excess mortality in this population for any cause of death. The overall standardized mortality ratio (SMR) for all causes was 0.81. Only the SMR for arteriosclerotic heart disease among black males showed a significant excess (SMR = 1.28). Examination of risks by major work areas such as production, utilities, maintenance, and other jobs, as well as by salaried and hourly pay grade, revealed no significant differences in cancer mortality by specific sites. Because the ratios for selected digestive cancers were above the all-cause SMR, this group of neoplasms is under further investigation as is the exposure profile of specific jobs within the industry.

Adult↗
PubMed1986

Bilateral angle-closure glaucoma in association with the acquired immune deficiency syndrome.

Two homosexual men, 35 and 42 years old, had bilateral acute angle-closure glaucoma in association with the acquired immune deficiency syndrome. In one patient, the angle-closure attack was the initial manifestation of AIDS. Choroidal effusion with secondary anterior rotation of the ciliary body at the scleral spur appeared to be the pathophysiologic mechanism. Pupillary block, angle crowding, and inflammatory synechial angle closure must be differentiated from anterior rotation of the ciliary body as the mechanism of the angle closure to provide optimal treatment. Whereas primary angle closures are treated with miotics and iridectomy, secondary angle closure may be worsened with this treatment. Cycloplegics and, if necessary, drainage of suprachoroidal fluid may be curative in AIDS-related angle closure associated with a choroidal detachment. Both patients died before the long-term efficacy of this treatment could be assessed.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Can the results of contemporary aortic valve replacement be improved?

Although the results of contemporary aortic valve replacement are excellent, cardiac surgeons must identify the factors that predict postoperative morbidity and mortality to develop alternative strategies for high-risk patients. Two hundred seventy-seven consecutive patients undergoing isolated aortic valve replacement between 1982 and 1984 were evaluated. Thirty-seven clinical and 13 preoperative hemodynamic variables were analyzed by univariate and multivariate statistics to determine the risk factors for postoperative morbidity and mortality. The operative mortality was 3%, the incidence of a postoperative low output syndrome was 12%, and the incidence of a perioperative myocardial infarction was 5%. A multivariate, logistic regression analysis found that age was the only the only independent predictor of mortality. Three factors independently predicted postoperative low output syndrome: age, the presence of coronary artery disease, and the peak systolic gradient in patients with aortic stenosis. Patients with aortic stenosis had a higher incidence of postoperative ventricular dysfunction (17%) than those with mixed valvular disease (9%) or aortic regurgitation (5%). Perioperative myocardial infarction was predicted by the extent of coronary artery disease. The incidence of perioperative myocardial infarction was higher in patients with triple-vessel coronary artery disease (13%) and those with left main stenosis (18%) than in patients with single- or double-vessel disease (4%) or those without coronary artery disease (4%). Because of the higher risk of aortic valve replacement in older patients, the risk-benefit ratio of the operation must be carefully assessed in the elderly. Improved methods of myocardial protection may reduce the risks for patients with aortic stenosis and symptomatic triple-vessel coronary artery disease.

Adult↗
PubMed1986

A device to measure X-ray magnification in preoperative planning for cementless arthroplasty.

Non-cemented press fit prostheses require a high degree of surgical precision for success. Since components vary in size by millimeters, the optimum preoperatively-determined size becomes a vital factor in selecting the correct size at the time of surgery. The preoperatively-determined component size is useful only if the information is obtained in a reliable and reproducible manner. The proper sequence combines X-rays of known magnification and templates of corresponding magnification. X-ray magnification is not a constant value even if the X-ray tube is maintained at a standardized height. Variables such as patient size and positioning make magnification measurements a necessity for every X-ray taken. A dense lead plate was designed for this purpose because commercially-available devices are over-penetrated by the X-ray exposures routinely used for hip roentgenograms. Manufacturers can provide templates in varying magnifications. This makes it possible to obtain a high correlation between the preoperative choice and the actual size chosen at surgery.

Hip Joint↗
PubMed1985

The use of dextran-40 during percutaneous transluminal coronary angioplasty: a report of three cases of anaphylactoid reactions--one near fatal.

Successful percutaneous transluminal coronary angioplasty is achieved by fracture of the atheromatous plaque and perhaps dilatation of the arterial walls to increase the luminal diameter of the artery. Because this "controlled" injury stimulates platelet adhesion on the subendothelial matrix, the use of dextran-40 in addition to heparin has been advocated. The overall incidence of Dextran-induced anaphylactoid reactions at our institution was 0.6% and of severe life-threatening reactions, 0.2%. With the recent doubts cast on the efficacy of dextran-40, the question arises regarding its routine use in PTCA.

Aged↗
PubMed1985

Percutaneous transluminal angioplasty of coronary saphenous vein bypass grafts.

Between December 1981 and August 1983, percutaneous transluminal angioplasty of saphenous vein grafts was performed in 14 men and 4 women, selected because of recurrent anginal symptoms and graft stenosis. The interval from bypass to angioplasty was 41 +/- 36 months. Of 24 lesions, 9 were at the proximal anastomosis, 13 in the distal segment and 2 in the middle segment of the vein graft. The primary success rate was 79%. Failure to cross the stenosis occurred in three patients and failure to dilate in one. The stenosis was reduced from a mean of 82% +/- 13% to 26% +/- 15%. No patient required emergency coronary artery bypass grafting but two underwent elective grafting after the angioplasty had failed. No patient sustained a Q-wave myocardial infarction and all who had a successful angioplasty were asymptomatic or much improved after the procedure. Angiographic follow-up was available in 12 of 14 patients (86%). Six patients had significant symptoms (Canadian Cardiovascular Society class II to III) and five of these had evidence of restenosis. Among the six patients who were asymptomatic, two had angiographic evidence of restenosis. The overall rate of restenosis was 58% (7 of 12). Repeat angioplasty was successful in three of the five patients in whom it was attempted. The authors conclude that percutaneous transluminal angioplasty of a saphenous vein graft for a localized area of stenosis is effective and safe, but there is a high rate of restenosis that possibly is due to intimal fibrous proliferation in saphenous vein grafts.

Adult↗
PubMed1985

Correlation of macrophage migration-inhibition factor and protection from challenge exposure in calves vaccinated with Salmonella typhimurium.

Migration of bovine macrophages under agarose was used to assess cellular immunity in 7 nonvaccinated calves and 9 calves vaccinated with Salmonella typhimurium. The 9 vaccinated calves were allotted to 4 groups. Group I calves were vaccinated twice orally with small doses of virulent S typhimurium; group II calves were vaccinated twice orally with genetically altered aromatic-dependent (aro-) S typhimurium SL3261; group III calves were vaccinated twice IM with small doses of virulent S typhimurium; and group IV calves were vaccinated twice IM with aro- S typhimurium SL1479. Samples of blood were obtained from these calves at 2 weeks after the 2nd vaccinal dose was given, and lymphocytes were harvested, using lymphocyte separation medium. Lymphocytes in serum-free medium were then incubated with S typhimurim antigen for 48 hours. Lymphocytes were then transferred to antigen-free medium and incubated for 48 hours, and the supernatant was assayed for the migration-inhibition factor (MIF). Lymphocyte supernatant was assayed for MIF by incubating it for 48 hours with 2.0 X 10(4) alveolar macrophages in agar wells. The macrophage migration distance was measured and compared with control values. Macrophage migration was inhibited in the presence of supernatant of lymphocytes from vaccinated calves that had been incubated with antigen, indicating the presence of the MIF in the supernatant. Migration distances, as a percentage of control, were 33% for group I calves (oral vaccination, virulent vaccinal organism), 60% for group II calves (oral vaccination, aro- vaccinal organism), 41% for group III (IM vaccination, virulent organism), and 25% for group IV (IM vaccination, aro- vaccinal organism).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Thrombosis of a prosthetic valve managed by thrombolysis: a case report.

Thrombosis of a prosthetic valve is one of the most serious cardiovascular events. Emergency replacement of the prosthetic valve has been the standard method of management but carries a high operative risk. This paper describes the successful use of streptokinase, given intravenously, to manage a patient with this complication in the acute phase. Eventually, operation was necessary because the presence of residual organized clot was suspected, but the procedure was performed electively 10 days later.

Adult↗
PubMed1985

Morbidity and mortality in mitral valve surgery.

To develop strategies for the management of high-risk patients, contemporary risk factors for operative mortality and postoperative ventricular dysfunction were identified in 214 patients undergoing mitral valve surgery in 1982 and 1983. Thirty-eight preoperative and perioperative variables were prospectively collected and analyzed by univariate and multivariate statistics. The overall mortality was 4.6% and the incidence of postoperative low-output syndrome (LOS) was 18.7%. Forty-seven patients with coronary artery disease (CAD) had a higher mortality and incidence of LOS (as evidenced by the need for inotropic drugs or counterpulsation to maintain blood pressure) (those with CAD 15% mortality, 40% LOS; those without CAD 2% mortality, 13% LOS; p less than .05). The presence of unstable angina and ischemic mitral regurgitation further increased the risk. Age was also a predictor of outcome. Patients who died or had LOS were older (those who died, 65 +/- 7 years, those with LOS, 58 +/- 11 years) than patients who survived and did not have postoperative dysfunction (those who survived, 53 +/- 11; those with no LOS, 53 +/- 11; p less than .01). Mitral regurgitation was associated with a higher (p less than .05) mortality and incidence of LOS (mortality 10.5%, LOS 36%; n = 76) than was mitral stenosis (mortality 0%, LOS 4%; n = 74) or mixed lesions (mortality 3%, LOS 15%; n = 64). In patients without CAD, mitral regurgitation remained a significant predictor of mortality and ventricular dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Comparison of two consecutive trials for treatment of childhood non-Hodgkin's lymphoma.

Two consecutive trials for the treatment of childhood non-Hodgkin's lymphoma were evaluated, carried out by the same cooperative groups. Group A: From June, 1973 to December, 1975, 50 evaluable patients under 16 years of age participated in a study that included vincristine and prednisone plus surgery and/or radiotherapy as induction. This was followed by 2400 rad of cranial radiotherapy plus 5 doses of intrathecal methotrexate-dexamethasone and anti-leukemia (6-mercaptopurine, methotrexate, cyclophosphamide) or anti-lymphoma (cyclophosphamide, vincristine, procarbazine, and prednisone) maintenance treatment. Group B: From January, 1976 to December, 1980, 55 evaluable patients participated in a consecutive study that added Adriamycin (doxorubicin) and cyclophosphamide to the former induction regimen. Central nervous system (CNS) prevention was performed with 5 doses of intrathecal methotrexate-dexamethasone. Maintenance treatment was the same. Prognostic factors as stage and primary site were comparable in both groups. A total of 33 (66%) of 50 children of Group A and 48 (87%) of 55 children of Group B achieved complete remission (P less than 0.005). Disease-free survival at 60 months was 27% in Group A and 49% in Group B; for Stage I-II, 30% in Group A and 85% in Group B (P less than 0.025); for Stage III-IV 28% in Group A and 36% in Group B (not significant). In Group A, 9.1% and in Group B, 8.3% had primary CNS relapse. Both maintenance schedules had the same relapse rate. It was concluded that: (1) the addition of Adriamycin and cyclophosphamide to vincristine-prednisone in Group B produces a higher rate of complete remission in Stage III-IV, a higher rate of disease-free survival in Stage I-II, and a higher survival rate in all stages; (2) CNS prevention with intrathecal methotrexate-dexamethasone is equally effective as cranial radiation plus intrathecal methotrexate-dexamethasone; and (3) anti-leukemia and anti-lymphoma maintenance are equally effective in the context of this study.

Adolescent↗
PubMed1984

Nonseminomatous malignant germ cell tumors in children. Multidrug therapy in Stages III and IV.

Thirty-five children with Stage III and IV nonseminomatous malignant germ cell tumors were treated, between June 1, 1977 and December 31, 1982, at Institut Gustave-Roussy, Villejuif, France, and Hospital General de Ninos, Buenos-Aires, Argentina: 11 sacrococcygeal, 12 ovarian, 6 testicular, 5 intrathoracic, and 1 intrabdominal site. All of them had yolk sac component with high level of AFP, seven had also elevated level of HCG. Thirteen patients had primary chemotherapy, 18 received chemotherapy after incomplete surgical excision, and 4 patients with testicular Stage III tumors had chemotherapy immediately following retroperitoneal lymphadenectomy after orchiectomy, because of persistently elevated AFP levels. The chemotherapy regimen for 1 year's duration, repeated every 21 days, and consisted of 6 courses of dactinomycin-Cytoxan (cyclophosphamide) D1 to D5 and vincristine, Adriamycin (doxorubicin) D21, bleomycin D23, and cisplatin D24. Only three patients received complementary radiotherapy. The toxicity of the chemotherapy regimen was severe, but only one death was due to the therapy (pulmonary fibrosis with bleomycin). The number of surviving patients without evidence of disease was 12 of 16 for Stage III and 12 of 19 for Stage IV. The 25-month survival rate was 63% with a follow-up of 11 months to 5.5 years (median, 22 months). This constitutes a dramatic improvement when compared with the survival rate of 21% of 48 similar patients treated at Institut Gustave-Roussy between 1968 and 1977 with surgery, radiotherapy, and chemotherapy (methotrexate, dactinomycin, and Cytoxan).

Abdominal Neoplasms↗
PubMed1984

Acute coronary artery occlusion during percutaneous transluminal coronary angioplasty treated by redilation of the occluded segment.

Acute occlusion of a coronary artery during percutaneous coronary angioplasty usually results in unremitting ischemia requiring emergency surgical intervention. Seven patients are described, in whom complete occlusion occurred during coronary angioplasty as a result of coronary artery dissection. Despite this, it was possible to reintroduce the balloon catheter immediately and redilate the vessel with abrupt reversal of clinical and electrocardiographic manifestations of ischemia. Six patients had no subsequent evidence of myocardial infarction. The seventh had a slight elevation of serum creatine kinase and transient electrocardiographic changes. All patients were discharged from the hospital without further intervention. Four patients had elective coronary artery bypass surgery (greater than 4 weeks after angioplasty) and three have remained asymptomatic or in improved condition since the coronary angioplasty. It is concluded that sudden occlusion of a coronary artery during coronary angioplasty can be safely treated by redilation in the acute stage.

Acute Disease↗
PubMed1984

Coronary risk factors and exercise test performance in asymptomatic hypercholesterolemic men: application of proportional hazards analysis.

The association of established coronary risk factors with submaximal graded treadmill exercise test performance was examined in 6,850 asymptomatic, white 34--59-year-old hypercholesterolemic men screened between 1973 and 1976 at 12 North American Lipid Research Clinics for participation in their Coronary Primary Prevention Trial. The prevalence of ischemic electrocardiographic responses (greater than or equal to 1 mm S-T segment depression) was 8.6%. The Cox proportional hazards method was adapted so as to take into account the level of exercise at which ischemic responses occurred and to which subjects without ischemic responses were exposed. The results were compared with those obtained by standard logistic regression. In both models, age, blood pressure, plasma cholesterol, and (inversely) plasma high-density lipoprotein cholesterol and alcohol consumption were significant independent predictors of an ischemic response to exercise. Surprisingly, ischemic responses were less frequent in smokers than in nonsmokers. However, when the proportional hazards method was used, cigarette smoking was weakly but significantly (p less than 0.01) predictive of an ischemic response on the treadmill. Results from this model differed from those of the logistic model because the former takes into account the reduced exercise capacity of smokers, which renders them less likely to reach workloads sufficient to induce myocardial ischemia. The proportional hazards model similarly demonstrated a possible beneficial effect of habitual physical activity which was not apparent in the logistic model. Quetelet index and plasma triglyceride were only weakly associated with the probability of an ischemic response, and did not contribute significantly to either model.

Adult↗
PubMed1984

Low serum 24,25 dihydroxyvitamin D in Duchenne muscular dystrophy.

Levels of serum 24,25(OH)2D3 (0.69 +/- 0.17 ng/ml) were lower in DMD patients than in age-matched controls (2.13 +/- 0.15 ng/ml). Circulating levels of 1,25(OH)2D3 and 25(OH)D3 were within the accepted normal range. Bearing in mind the proposed pathophysiologic role of calcium in DMD and the influence of vitamin D metabolites on muscle ATP and protein synthesis, as well as on sarcoplasmic reticulum calcium transport and muscle mitochondrial calcium content, the above findings of low or deficient 24,25(OH)2D3 levels in DMD could be meaningful from the etiologic and therapeutic points of view.

24,25-Dihydroxyvitamin D 3↗