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Biomedical subjects

B Lazarus

Publications and source records attributed to B Lazarus.

At least 19 recordsLinked to original sources
PubMed2000

The role of mast cells in ischaemia-reperfusion injury in murine skeletal muscle.

To determine the role of mast cells in ischaemia-reperfusion (IR) injury to skeletal muscle, W(f)/W(f) mast cell-deficient and their corresponding wild-type mice were subjected to 70 min tourniquet ischaemia and 24 h reperfusion. As measured by nitroblue tetrazolium (NBT) staining, muscle viability was 9% in wild-type and 94% in mast cell-deficient animals (p<0.001). Assay of residual lactate dehydrogenase activity within the injured muscle (p<0.05) and histological examination confirmed the greater muscle necrosis in treated wild-type than in treated mast cell-deficient mice. There was no significant difference in the degree of neutrophil infiltration, tissue myeloperoxidase content or water content of IR-injured muscle in the two mouse phenotypes. To determine further the role of mast cells in IR injury, wild-type mice were treated 30 min prior to reperfusion with an intraperitoneal dose of either saline or the mast cell-stabilizing agent lodoxamide trometamol (2.5, 7.5, 25 or 75 mg/kg). Twenty-four hours after removal of the tourniquet, saline-treated gastrocnemius muscle had a mean viability of 14% compared with 28% (p<0.05) and 48% (p<0.01) after 25 mg/kg and 75 mg/kg of lodoxamide treatment, respectively. The ability of lodoxamide to stabilize mast cells was confirmed by histological examination. Ischaemic muscle reperfused for 1 h showed much less degranulation of mast cells in mice pretreated with lodoxamide (50 mg/kg) than in saline-treated controls. These findings suggest that mast cells are a major source of mediators of necrosis in IR injury to skeletal muscle.

Animals↗
PubMed1992

Is polyurethane lead insulation still controversial?

A controversy arose some 10 years ago over the reliability of polyurethane lead insulation. On the basis of one of the longest standing and largest databanks worldwide, the authors compare the cumulative survival of several thousand polyurethane, standard silastic, and high-performance silastic electrodes as it pertains to the failure criterion described as insulation degradation. With the possible exception of the Medtronic 6972 (Medtronic, Inc.) electrode, polyurethane electrodes have a 100% reliability at 84 months, which is similar to silastic electrodes.

Databases, Factual↗
PubMed1988

Clinical experience with new leads.

Recent developments in cardiac pacemaker electrodes have resulted in significant benefits to the group of pacemaker patients as a whole. The results of analysis of 2,818 chronic pacemaker electrodes are presented. These electrodes are divided into major categories according to their particularities: platinum iridium, elgiloy, carbon-tip, anodized platinum and granulated iridium-platinum. All leads were in the ventricular position. The results of acute and chronic threshold measurements reveal that carbon-tipped electrodes appear to have the most favorable overall characteristics. This will have a major influence on long-term pacing practices.

Carbon↗
PubMed1986

Clinical experience with 910 carbon tip leads: comparison with polished platinum leads.

Since 1980, we have implanted 910 carbon tip leads from three different manufacturers. The pacing thresholds from these leads were compared to those of standard polished platinum electrode configurations. Our major findings are that while acute voltage thresholds are not significantly different, two of the three carbon tip leads that we used in the study have statistically lower chronic thresholds then polished platinum leads (p less than or equal to 0.01).

Carbon↗
PubMed1984

The effect of upper gastrointestinal endoscopy on arterial O2 tension in smokers and nonsmokers with and without premedication.

Fiberoptic upper gastrointestinal endoscopy has become an accepted procedure with recognized and acceptable complication rates. Recently, significant hypoxemia during upper gastrointestinal endoscopy has been identified. This report evaluates changes in arterial blood gases and investigates the effects of drugs, smoking, and length of procedure. Upper gastrointestinal endoscopy was performed on 60 patients--15 patients in four different groups. Group I and II were smokers and nonsmokers who received sedation; groups III and IV were smokers and nonsmokers who received no sedation. A significant drop in PaO2 was noted in each group. Sedation, length of procedure, or smoking did not affect the PaO2 levels significantly. No significant change in PaCO2 was noted in any of the four groups. A V/Q mismatch related to vasospasm and/or bronchospasm is proposed as the main reason for the hypoxemia.

Adolescent↗
PubMed1983

Exercise, diet, or physical characteristics as determinants of HDL-levels in endurance athletes.

Serum lipids, lipoproteins, apolipoproteins, physical characteristics, and 10-day dietary records of 20 male distance runners (aged 20-42 years) were compared with those of 14 sedentary controls (aged 23-34 years). Runners had significantly greater levels (mean +/- SD) of high density lipoproteins (HDL) whether estimated as HDL-cholesterol (66 +/- 12 vs 46 +/- 10 mg/dl) or as the major HDL apolipoproteins, apoA-I (170 +/- 36 vs 124 +/- 27 mg/dl) or apoA-II (39 +/- 5 vs 34 +/- 4 mg/dl). Runners were leaner with considerably less body fat (8.3 +/- 1.7 vs 16.2 +/- 3.9%) than the sedentary men despite consuming 20% more calories. Moreover, the additional calories consumed were largely carbohydrate. This comparison illustrates that high absolute quantities of dietary carbohydrate do not depress HDL levels in lean individuals engaged in exercise training. Furthermore, the results suggest that dietary factors may be as important as exercise itself in producing the lipoprotein pattern characteristic of endurance athletes.

Adult↗
PubMed1981

Acute effects of a single exercise session on serum lipids in untrained men.

Acute reductions in triglycerides and calculated low density lipoprotein cholesterol with little change in high density lipoprotein cholesterol have been reported in trained men after a single exercise session. To examine if a similar acute exercise effect occurs in sedentary subjects, wer measured triglycerides, total cholesterol, and high density lipoprotein cholesterol in eight sedentary men before and for 66 hours after a single 30-minute exercise session. The exercise was designed to simulate a typical exercise training session for untrained subjects. An isolated reduction in estimated low density lipoprotein cholesterol was observed 66 hours after the exercise. All other serum lipid measurements at 5 minutes and 1, 4, 18, 42, and 66 hours after exercise did not differ from pre-race concentrations. Consequently, the reductions in triglycerides and low density lipoprotein cholesterol and increase in high density lipoprotein cholesterol reported in previously sedentary subjects after exercise training are a chronic rather than an acute exercise effect.

Adult↗
PubMed1981

Comparison of the results and reproducibility of arm and leg exercise tests in men with angina pectoris.

The results and reproducibility of arm and leg exercise tests were compared in 11 men with angina pectoris induced by both forms of testing. Leg testing was performed using a bicycle ergometer; arm testing was performed using the same apparatus modified to permit arm cranking. Subjects performed 2 days of arm and 2 days of leg testing over a 2 week period. Four tests were performed on each test day. The duration of exercise, oxygen uptake, heart rate, systolic and diastolic blood pressures and the rate-pressure product were determined at the onset of angina. Within day and between product were determined at the onset of angina. Within day and between day coefficients of variation were low and similar for arm and leg tests, indicating that both forms of testing are highly reproducible. Performing four tests on a single day did little to reduce variability. Oxygen uptake increased between the first and second arm or leg test on a single day, but there was little change after the second test. Repetition of the arm and leg tests did not affect performance over the study period. It is concluded that the reproducibility of arm exercise testing in men with angina pectoris is comparable with that of leg exercise. Subjects with angina induced by arm exercise who cannot perform leg testing can be evaluated and followed up with arm exercise tests.

Angina Pectoris↗
PubMed1981

Effect of exercise training on the untrained limb exercise performance of men with angina pectoris.

This study examined the exercise capacity of trained and untrained limbs in men with angina pectoris before and after 8 weeks of arm ( n = 4) or leg (n = 7) physical training or a control (n = 4) period. Time to angina (mean +/- standard deviation) increased 3.6 +/- 2.7 minutes (p less than 0.01) during trained limb and 1.6 +/- 1.2 minutes (p less than 0.01) during untrained limb exercise. Myocardial oxygen demand at angina estimated by the product of heart rate and systolic blood pressure did not change with training. At a constant subanginal work load, rate-pressure product x 10(-2) was reduced by 35 +/- 22 (p less than 0.001) during trained limb and by 18 +/- 27 (p less than 0.05) during untrained limb exercise. The decrease in rate-pressure product with both trained and untrained limbs was greatest in subjects with the highest rate-pressure product at angina before training. Control subjects showed no change in any exercise measurement. Exercise training increases the exercise capacity of untrained limbs in patients with angina pectoris by a generalized training effect not dependent on adaptations in trained skeletal muscle. The improvement for both trained and untrained limbs results from a reduced rate-pressure product at subanginal work loads rather than from an increase in myocardial oxygen delivery. Subjects with the highest pretraining coronary arterial oxygen supply at the onset of angina benefit most from physical training.

Angina Pectoris↗
PubMed1980

[Arrhythmia in patients with demand pacemakers caused by faulty conduction material in the electrode. 36 cases--Value of Holter monitoring].

36 cases of paroxysmal pacing failure in patients with demand pacemakers are reported. The possible causes of pacing lead problems, excluding inhibition by muscular contractions, are related to the distal extremity at the electrode itself, on the lead (rupture) or at the connection between the lead and the pulse generator. The recognition of the precise cause of the pacing failure leads to appropriate treatment. These arrrythmias are not always easy to detect and Holter monitoring is a very useful means of diagnosis.

Arrhythmias, Cardiac↗
PubMed1978

Methods for recording intermittent contact signals in demand pacemaker arrhythmias (11 cases).

This report describes some of the various techniques which may be used to demonstrate intermittent and/or incomplete fracture of a pacing lead. Eleven patients treated with an R-wave-inhibited demand pacer showed signs of paroxysmal arrhythmias. Intraoperative recordings of the ventricular electrogram showed the presence of spurious signals mimicking an R-wave. These signals varied from patient to patient but remained morphologically constant when a given technique was used in a given case. The most significant signals were picked up when pacing and recording on the same lead.

Arrhythmias, Cardiac↗