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Biomedical subjects

J Weiss

Publications and source records attributed to J Weiss.

At least 397 records · Page 22Linked to original sources
PubMed1983

Localization of the accessory pathway in the Wolff-Parkinson-White syndrome from the ventriculo-atrial conduction time of right ventricular apical extrasystoles.

In 18 consecutive patients with the Wolff-Parkinson-White syndrome undergoing electrophysiologic study, the ventriculo-atrial conduction time of right ventricular apical extrasystoles which advanced atrial activation during circus movement tachycardia was studied in relation to accessory pathway location. Accessory pathway location was determined by delta wave morphology during maximal pre-excitation, mapping of atrial activation during circus movement tachycardia and ventricular pacing, the effect of bundle branch block on ventriculo-atrial conduction time during circus movement tachycardia, and the effect of pacing from different sites in the atria on the stimulus-to-delta wave interval. In 7 patients with septal accessory pathways, ventriculo-atrial conduction time was similar during circus movement tachycardia and following right ventricular apical extrasystoles (mean difference 0 +/- 6 ms, range -5 to +10 ms). In contrast, in 11 patients with a left free wall accessory pathway, ventriculo-atrial conduction time increased by 46 +/- 15 ms (range 15 to 65 ms) following right ventricular apical extrasystoles. Therefore, measurement of the ventriculo-atrial conduction time of right ventricular extrasystoles during circus movement tachycardia provides an easy way to distinguish between septal and left free wall accessory pathways. This finding may be of particular use in determining the location of concealed bypass tracts.

Adolescent↗
PubMed1983

An unusual mechanism of initiation of circus movement tachycardia in a patient with concealed Wolff-Parkinson-White syndrome.

Infranodal conduction delay is an uncommon mechanism of initiation of circus movement tachycardia in the Wolff-Parkinson-White syndrome. A patient with a concealed left free wall atrioventricular accessory pathway who underwent electrophysiological study is presented. During atrial extrastimulus testing, a pattern of alternating bundle branch block was observed and was most marked after the administration of intravenous procainamide. Conversion from right bundle branch block to left bundle branch block was reproducibly associated with the initiation of circus movement tachycardia utilizing the normal conducting system antegradely and the accessory pathway retrogradely. Initiation of tachycardia was critically related to the increase in the HV interval associated with left bundle branch block. Of interest, conduction in the right bundle branch became progressively slower as the prematurity of the atrial extrastimulus increased, whereas conduction time through the left bundle branch remained fixed prior to block. Implications of these findings are discussed. To our knowledge, this is the first report of alternating bundle branch block during atrial extrastimulus testing as a mode of initiation of circus movement tachycardia in the Wolff-Parkinson-White syndrome.

Adult↗
PubMed1983

Vulnerability and immune response. An overview.

A summary of the scope and mechanisms of the immune response is given and the hypothesis is put forth that, from the immunologic point of view, infections and neoplasms are the result of deficient recognition or arousal of effective defense systems against a foreign invader. An overview is provided of animal and human natural history, epidemiological, or experimental studies relating psychosocial variables to host defenses against infectious and neoplastic disorders; these studies implicate the involvement and competency of the immune system. An exploratory study is reported examining the relationship of a depressive reaction in 7 human subjects to the immune function of polymorphonuclear neutrophils. The 3 most depressed and/or hostile subjects showed significant inhibition of normal (chemiluminescence) immune response of polymorphonuclear neutrophils as compared to nondepressed healthy subjects. This inhibition of the immune response could not be attributed to the effects of pharmacologic agents, plasma cortisol levels, or differences in circadian rhythm.

Adjustment Disorders↗
PubMed1983

Role of charge and hydrophobic interactions in the action of the bactericidal/permeability-increasing protein of neutrophils on gram-negative bacteria.

We have recently provided evidence suggesting that the action of purified cationic bactericidal/permeability-increasing protein (BPI) from neutrophils on susceptible gram-negative bacteria requires saturation binding to negatively charged surface sites (Weiss, J., S. Beckerdite-Quagliata, and P. Elsbach, 1980, J. Clin. Invest., 65: 619-628.)We now show that this charge interaction is necessary but not sufficient to produce the effects of BPI on the envelope and on viability. By altering the hydrophobic properties of the bacterial (outer) membrane, it is possible to separate saturation binding from the biological action of BPI, indicating that steps beyond surface binding are needed for the antibacterial action. Outer membrane properties were modified by (a) reducing temperature during BPI-Escherichia coli interaction; (b) growing E. coli at 42 degrees C to increase the saturated fatty acid content of membrane phospholipids; and/or (c) using smooth E. coli with a natively less fluid outer membrane. Hydrophobic interaction chromatography on phenyl-Sepharose and measurement of sensitivity to the hydrophobic antibiotic rifampicin were used to monitor the changes in hydrophobic properties of the bacterial outer membrane produced by these manipulations. Nearly all BPI can be removed from the bacterial surface by 80 mM MgCl(2) or by trypsin. At 37 degrees C, removal of BPI results in repair of the envelope alterations, but viability is irreversibly lost, even when Mg(2+) is added after only 15 s of exposure of the bacteria to BPI. However, under conditions of reduced outer membrane hydrophobicity, when saturation binding still occurs within 30 s, E. coli can be rescued by addition of Mg(2+) after up to 5-min exposure to BPI, indicating retardation of postbinding steps. We conclude that after initial binding BPI must enter into a hydrophobic interaction with the outer membrane in order to produce its antibacterial effects. These postbinding events reversibly mediate the membrane perturbations and irreversibly trigger the bactericidal action of BPI.

Animals↗
PubMed1983

House officer management of the febrile child. A survey.

Questionnaires were used to survey 95 pediatric house officers in order to determine their reasons and methods for treating fever, as well as their knowledge of fever physiology. The reasons given for treating fever were to make the child comfortable (99%), to prevent seizures (63%), and to satisfy parents (44%). The average temperature at which antipyretic medication was started was 38.6 +/- 0.3 C. Alternating doses of aspirin and acetaminophen were used by 53 per cent, and sponging was recommended by 76 per cent of the residents. The average temperature at which sponging was started was 39.5 +/- 0.6 C. The percentage of house officers who use sponging and/or alternating doses of antipyretics differed greatly from hospital to hospital. Sixty-one per cent of the residents felt that fever is a defense mechanism which does not require treatment. Despite this belief, the majority of these residents use vigorous means to lower fever in children.

Acetaminophen↗
PubMed1983

Reproductive physiology and penile papillae morphology of rats after sexual experience.

Research which examined acute and chronic changes in the reproductive physiology and morphology of male rats after mating is reported. A group of sexually experienced (SE) and a group of sexually inexperienced (SI) animals were castrated on day 110 of age. Those animals and a group of SE and a group of SI gonadally intact males were left undisturbed for 30 days, and all animals were killed on day 140 of age. Testes, epididymides, penes and levator ani muscles were heavier in SE males, and those males had increased titres of circulating testosterone. Moreover, testicular sperm production was higher in SE than SI males immediately after the weekly copulatory sessions. Scanning electron microscopic examination of the surfaces of the glans penes revealed that sexual experience slowed the decay of penile papillae. More importantly, SE-intact males possessed uniformly large penile papillae, while the large papillae on penes from SI-intact males were interspersed with smaller papillae in various stages of development. The results suggest that mating provokes substantial changes in the endocrine integrity, fecundity and penile morphology of male rats.

Animals↗
PubMed1983

Computerized tomography in pericardial disease.

In many patients conventional radiographic procedures aid the detection of pericardial pathology. Echocardiography is undoubtedly the most satisfactory investigation for assessing pericardial thickening and fluid. However, in special circumstances CT of the mediastinum is able to offer additional information. Small quantities of pericardial air, associated tumor masses, and the extent of a pericardial effusion or pericardial calcification can be displayed most advantageously by CT.

Adult↗
PubMed1982

The role of phospholipase A2 lysines in phospholipolysis of Escherichia coli killed by a membrane-active neutrophil protein.

Purified rabbit bactericidal/permeability-increasing protein at bactericidal concentrations is a membrane-perturbing agent that triggers hydrolysis of envelope phospholipids of a phospholipase A-less Escherichia coli (S17) mutant by a highly basic (pI greater than 10) phospholipase A2, purified from Agkistrodon halys blomhoffii snake venom. Most other purified phospholipases A2 do not degrade the phospholipids of E. coli killed by the bactericidal protein. To study the role of enzyme charge in bactericidal protein-dependent phospholipid hydrolysis, lysines of the Agkistrodon phospholipase A2 were modified, either by carbamylation (decreases net charge), or by reductive methylation (no delta charge). Incorporation of [14C]cyanate or [14C]formaldehyde and amino acid analysis served to monitor modification. Modification appears to be limited to epsilon-NH2 groups. Incorporation of up to 5 mol of cyanate or formaldehyde/mol of enzyme did not affect catalytic activity. In contrast, incorporation of, on average, 1 mol of either reagent/mol of protein reduced by 80% the activity of the enzyme toward E. coli S17 killed by the bactericidal protein. Since this loss is similar with carbamylation and reductive methylation, the role of the epsilon-NH2 group in the bactericidal protein-dependent hydrolysis seems independent of charge. Thus, the lysines in this phospholipase A2 are not essential for catalysis and substrate binding, but are essential for the action of this enzyme on E. coli killed by the bactericidal protein.

Animals↗
PubMed1982

Cell-type differences in the serum and cyclic AMP-dependent regulation of ornithine decarboxylase activity in two cultured fibroblast types.

Serum re-feeding stimulated ornithine decarboxylase (ODC) activity 8 to 10-fold in FS fibroblasts and 5 to 8-fold in 3T3 fibroblasts. Addition of dibutyryl cyclic AMP or 3-isobutyl-1-methylxanthine at the time of serum re-feeding further stimulated ODC activity in 3T3 fibroblasts but inhibited the serum stimulation of ODC activity in FS fibroblasts. It is suggested that serum and cyclic AMP independently regulate ODC activity in cultured fibroblasts.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Multiple localizations of adenylate cyclase in rat hippocampus. A histochemical study.

A new method for the histochemical demonstration of adenylate cyclase activity, introduced and biochemically tested by Poeggel et al. (1981 a), was employed in nervous tissue. Using this method a multiple pattern of activity was detectable. Activity occurs in nervous as well as glial elements. Biochemical results and physiological conclusions could be confirmed by ultrahistochemical visualization of adenylate cyclase activity in nervous tissue. The specificity of the reaction is controlled by a number of variations of the incubation methods.

Adenylyl Cyclases↗
PubMed1982

Effect of isoproterenol on the anterograde refractory period of the accessory pathway in patients with the Wolff-Parkinson-White syndrome.

To evaluate the effect of beta adrenergic stimulation on the duration of the anterograde refractory period of the accessory pathway, isoproterenol was infused in seven patients with the Wolff-Parkinson-White syndrome. In two patients the effect of isoproterenol was studied during long-term oral amiodarone administration. To avoid rate-related changes induced by isoproterenol, the anterograde refractory period of the accessory pathway was determined using the single test stimulus method at identical basic cycle lengths. Isoproterenol shortened the anterograde refractory period of the accessory pathway in six of the seven patients studied. In two of the three patients with an initial anterograde refractory period of the accessory pathway of equal to or less than 290 ms, shortening measured 30 ms. In three patients having an anterograde refractory period of the accessory pathway of more than 290 ms, isoproterenol abbreviated these values by 30, 60 and 80 ms, respectively. The greatest amount of shortening was observed in patients having the longest initial values for the anterograde refractory period of their accessory pathway. In the two patients receiving oral amiodarone therapy, isoproterenol shortened the anterograde refractory period of the accessory pathway by 180 and 60 ms, respectively, indicating that the effect of isoproterenol can not be prevented by long-term oral amiodarone administration. Our observations may be of importance in patients with the Wolff-Parkinson-White syndrome and atrial fibrillation. They suggest that beta adrenergic stimulation induced by hypotension or anxiety may result in shortening of the anterograde refractory period of the accessory pathway, leading to increased ventricular rates during atrial fibrillation.

Adult↗
PubMed1982

A modified life table method to study congenital genetic disorders: an application in sickle cell anemia.

A modified life table procedure is introduced designed to study the survival of patients with congenital genetic disorders with the endpoint defined by a complication or death. It uses the ages of the patients as the time axis as in "population' or "current' life tables, and it allows patients to enter and exit the study as in survival life tables. The procedure uses the exact length of time that each patient is observed in the study to determine the conditional probabilities of developing the complication. The proposed procedure is especially helpful in studying recurrent complications or events that occur frequently. The proposed life table procedure is demonstrated in the study of the conditional probability of developing a sickle cell crisis in 509 patients with sickle cell anemia (SS) with different number of prior crises. The demonstration is intended to illustrate the use of the proposed method and not to investigate the clinical severity of sickle cell anemia. It was found that the risk of crisis was to investigate the clinical severity of sickle cell anemia. It was found that the risk of crisis was positively related to the number of prior crises in SS patients (P less than 0.001). This trend was significant in the first three decades of life.

Actuarial Analysis↗