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Biomedical subjects

M Josephson

Publications and source records attributed to M Josephson.

32 records · Page 2Linked to original sources
PubMed1995

Intermittent preexcitation and mesothelioma of the atrioventricular node: a hitherto undescribed entity.

This is the first documented case of spontaneous intermittent preexcitation associated with mesothelioma of the atrioventricular (AV) node. A 66-year-old male with recurrent atrial arrhythmias, palpitations, heart failure, and marked intra-atrial conduction defect that required a pacemaker died during sleep. Electrophysiologic study revealed left free-wall bypass tract with marked intra-atrial conduction defect and prolonged conduction across the bypass tract. With atrial pacing, high degrees of block were noted in the bypass tract. Serial section of the conduction system and both AV rims revealed two left posterior and lateral bypass pathways with patchy areas of fibrosis. A large mesothelioma (benign AV nodal tumor) almost completely replaced the AV node. In addition, there was marked fatty infiltration of the atria. In summary: (1) the intermittent preexcitation with prolonged conduction across the bypass tract and block with atrial pacing were probably related to the incomplete patchy degenerative changes in the bypass tract, and/or almost complete replacement of the AV node by the tumor; (2) the intra-atrial conduction defect was probably related to the replacement of the AV node by mesothelioma and/or the fatty infiltration of the atria; and (3) the paroxysmal atrial arrhythmias probably reflect the marked atrial pathology.

Aged↗
PubMed1991

Predictors of in-hospital mortality after DC catheter ablation of atrioventricular junction. Results of a prospective, international, multicenter study.

BACKGROUND: The Catheter Ablation Registry was the first international, multicenter, prospective study of the safety and efficacy of catheter ablation. METHODS AND RESULTS: From August 1987 through March 1990, the study comprised 136 patients in whom only DC energy was used in attempted production of third-degree atrioventricular block to treat uncontrollable supraventricular tachycardias. Eight patients died during hospitalization for ablation. In seven (5.1%), the ablation may have contributed to their deaths. Causes of death included ventricular fibrillation (five patients, three with polymorphic ventricular tachycardia), progressive heart failure (one patient), and respiratory failure (two patients, one dying after resuscitation from ventricular fibrillation). Compared with survivors, patients who died were more likely to have had prior aborted sudden death (38% versus 2%, p less than 0.05), congestive heart failure (88% versus 22%, p less than 0.001), cardiomyopathy (50% versus 16%, p less than 0.05), lower baseline systolic blood pressure (106 versus 138 mm Hg, p less than 0.001), prolonged baseline and postablation corrected QT interval (p less than 0.01), and markedly reduced ejection fraction (27% versus 52%, p less than 0.001). Ablation successfully produced third-degree atrioventricular block in 88% of the patients who died and in 83% of survivors. CONCLUSIONS: Catheter ablation of the atrioventricular junction with DC energy carries a significant, previously unrecognized risk of death (5.1%), particularly from lethal arrhythmias, when applied to patients with severe left ventricular dysfunction. Great care should be taken in these seriously ill patients to guard against postablation ventricular arrhythmias.

Bundle of His↗
PubMed1990

[Subendocardial resection in the surgical treatment of ventricular arrhythmia in patients with ischemic heart disease].

The authors have much experience in diagnosing and managing ventricular arrhythmias in patients with coronary heart disease. In most cases, the arrhythmogenic areas are present in the subendocardium and surgeries aimed at improving myocardial revascularization prove to be frequently ineffective in managing arrhythmias. Subendocardial resection proposed by the authors was used in 284 patients. Mortality rates were in 15%, the deaths were mainly due to phenomena of heart failure. Positive results were achieved in 160 (67%) patients. To evaluate the efficacy of the surgical management, the authors consider it advisable to apply programmed endocardial stimulation. The value of pre- and intraoperative mapping is the most important factor that determines the outcome of the surgical management. Subendocardial resection should be regarded as the method of choice just at early stages of the disease in patients with recurrent ventricular tachycardias occurring after acute myocardial infarction.

Aged↗
PubMed1989

Fractionated endocardial electrograms are associated with slow conduction in humans: evidence from pace-mapping.

Fractionated ventricular electrograms recorded during catheter mapping may arise from areas of asynchronous depolarization associated with slow conduction, the substrate for reentrant ventricular tachycardia, but can also be a nonspecific abnormality or even artifact. To determine whether fractionated sinus rhythm electrograms are associated with slow conduction in humans, the results of endocardial catheter mapping and pacing at 133 endocardial sites in 13 patients were analyzed. Eleven patients had sustained monomorphic ventricular tachycardia and two patients had old myocardial infarction without ventricular tachycardia. Functional evidence of slow conduction at the recording site was assessed by pacing at that site and measuring the interval between the stimulus artifact (S) and the onset of the QRS complex in the 12 lead electrocardiogram (ECG). During pacing at 89 of 90 sites without fractionated sinus rhythm electrograms, the S-QRS interval was less than 40 ms, a value consistent with rapid propagation of the stimulated wave front away from the pacing site. During pacing at 21 (49%) of 43 sites with fractionated sinus rhythm electrograms, the S-QRS interval was greater than 40 ms (range 40 to 140), consistent with slow conduction at the pacing site (p less than 0.001 versus nonfractionated sites). In 9 of the 11 patients with ventricular tachycardia analysis of the paced QRS configuration, electrograms during induced ventricular tachycardia or programmed stimulation during tachycardia suggested that a site with a long S-QRS interval during pacing was located at or near a ventricular tachycardia circuit. Therefore, fractionated sinus rhythm electrograms are often associated with slow conduction, which may be the substrate for reentrant ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Hemodynamic effects of flestolol, a titratable short-acting intravenous beta-adrenergic receptor blocker.

The hemodynamic effects of flestolol were evaluated in 30 patients undergoing routine cardiac catheterization. Hemodynamic measurements were obtained during baseline (prior to flestolol), at steady state during IV flestolol infusion (1, 5, and 10 micrograms/kg/min) and at 20 to 30 minutes after discontinuation (postinfusion). Flestolol-induced hemodynamic changes were similar to those induced by other beta blockers without intrinsic sympathomimetic activity. Significant dose-dependent reduction in heart rate, rate pressure product, and increase in peripheral vascular resistance were seen. Flestolol produced clinically insignificant decrease in myocardial contractility as shown by slight decrease in LVdp/dt, CI, and LVEF. Hemodynamic data from patients with paced heart rate, further confirms a direct mild cardiac depressant effect of flestolol, a finding common to other beta blockers. Consistent with the short elimination half-life of flestolol (t1/2 = 6.5 minutes), most of the hemodynamic changes rapidly returned to preinfusion level within 20 to 30 minutes following its discontinuation. Thus flestolol, with its unique pharmacokinetic profile and titrability, may be beneficial in the treatment of critically ill patients.

Adrenergic beta-Antagonists↗
PubMed1988

Resetting of ventricular tachycardia: implications for localizing the area of slow conduction.

Analysis of local endocardial electrograms recorded during reentrant ventricular tachycardia does not provide direct information as to the participation of the recording site in the tachycardia circuit. To determine if programmed electrical stimulation at the recording site can assist in localizing areas of slow conduction that are participating in the tachycardia circuit, seven patients with sustained monomorphic ventricular tachycardia were studied. The cardiac cycle was scanned with single stimuli delivered during ventricular tachycardia at multiple endocardial sites. In four patients, an endocardial site was identified at which stimuli advanced the tachycardia with marked conduction delay and without alteration of the ventricular activation sequence, as indicated by a lack of change in the configuration of the QRS complex and endocardial electrograms distant from the stimulation site. This finding was seen only during stimulation at sites displaying abnormal electrograms and is consistent with premature depolarization of an area of slow conduction within the tachycardia focus by stimuli delivered at or near that area. Attempted endocardial catheter ablation at or adjacent to these sites in three patients was followed by persistent noninducibility of ventricular tachycardia in one patient, marked modification of the configuration and cycle length of inducible tachycardia in one patient and transient noninducibility of tachycardia in one patient. Programmed electrical stimulation during ventricular tachycardia at sites with abnormal electrograms may provide information about the proximity of the stimulation site to the tachycardia circuit.

Aged↗
PubMed1986

Disaturated phosphatidylcholine as a fetal lung maturity test: lack of interference by seminal ejaculate as a contaminant in vaginally pooled amniotic fluid samples.

Seminal ejaculates obtained from four men were added to amniotic fluid pools. Lecithin/sphingomyelin ratios in amniotic fluid were significantly lowered in the presence of small amounts of contaminating semen. In contrast, the determination of disaturated phosphatidylcholine was not affected by the presence of this contaminant.

Amniotic Fluid↗
PubMed1980

Mitochondrial biogenesis during fungal spore germination. Purification, properties and biosynthesis of cytochrome c oxidase from Botryodiplodia theobromae.

1. Cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) was purified from the mycelial fungus Botryodiplodia theobromae by sodium cholate and ammonium sulfate solubilization, ammonium sulfate fractionation, and DEAE-cellulose chromatography. The purified enzyme contained 6--7 nmol heme a/mg of protein. The specific activity of the purified enzyme was 2.1--2.3 . 10(3) k (min-1) per mg of protein with 15 mumol ferrocytochrome c and at pH 5.9 and optimal phosphate and Tween 80 concentrations (65 mM and 0.1%, respectively). The Km for ferrocytochrome c was determined to be 1.2--1.3 . 10(-5) M, while at infinite substrate concentration the enzyme catalyzed the oxidation of about 60 mumole of ferrocytochrome c/min per mg of protein. Sedimentation behavior and kinetic evidence suggest that the purified enzyme exists as aggregates of the single molecule. The purified B. theobromae cytochrome c oxidase with its 428 nm Soret absorption maximum may be similar if not identical to oxygenated forms of the enzyme from other fungal species. 2. The purified enzyme was shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis to consist of seven polypeptides with the following respective molecular weights: I, 41 000; II, 28 000; III, 19 000; IV, 14 800; V, 12 800; VI, 11 500; and VII, 9300. Biosynthesis studies showed that the three highest molecular weight polypeptides of the enzyme were synthesized on mitochondrial ribosomes, and the four smaller polypeptides were products of cytoplasmic ribosomes.

Cytochrome c Group↗
PubMed1978

Mitochondrial biogenesis during fungal spore germination: effects of the antilipogenic antibiotic cerulenin upon Botryodiplodia spores.

Germination of spores of the fungus Botryodiplodia theobromae was inhibited by the antilipogenic antibiotic cerulenin. The spores remained viable in the presence of the antibiotic, however, and after prolonged incubation they were able to overcome the inhibition. Cerulenin inhibition of germination was reversed by Tween 40 and Tween 60 (derivatives of palmitate and stearate, respectively), but not by representatives of a range of free fatty acids or their soaps. Cerulenin abolished incorporation of [14C]acetate into sterols and triglycerides and reduced its incorporation into fatty acids by 69%. Cyanide-sensitive oxygen consumption by spores incubated in the presence of cerulenin was greatly reduced throughout germination, and the activity of cytochrome c oxidase was no more than 13% of the activity in untreated spores, even after prolonged incubation. However, low-temperature difference spectra of mitochondrial extracts showed that the cerulenin-treated spores accumulated a threefold excess of cytochrome a, whereas the cellular concentrations of cytochroms c and b were identical to those of untreated spores. Cerulenin treatment sharply reduced the rates of whole spore protein and RNA synthesis. Cerulenin had no effects upon mitochondrial morphology which could be discerned with an electron microscope.

Antifungal Agents↗
PubMed1977

Mitochondrial biogenesis during fungal spore germination: respiratory cytochromes of dormant and germinating spores of Botryodiplodia.

The mitochondrial respiratory cytochrome contents of dormant and germinating conidia of Botryodiplodia theobromae were examined. Oxidized versus reduced difference spectra at 77 degrees K of whole mitochondria from physiologically mature germinated spores showed a typical a-band pattern for cytochromes c, b, and a, with absorption maxima at 549, 554 + 559, and 604 nm, respectively, whereas the difference spectrum of the counterpart mitochondrial fraction from dormant spores showed no cytochrome a bands. However, a fraction prepared from dormant spore mitochondria by detergent extraction and (NH4)2SO4 fractionation contained readily detectable quantities of cytochromes c and b (as shown by the a and Soret absorption bands), but it did not contain the a or Soret bands of cytochrome a observed in a counterpart preparation from germinated spores. The pyridine hemochromogen preparation from the dormant spore mitochondria contained no material that is spectroscopically characteristic of a-type heme and protoheme. These results suggest that cytochrome a is not present as a functional molecule in dormant spores. The first spectroscopically detectable cytochromes were observed in whole mitochondria at 210 min of spore germination, and the amount of each of the cytochromes increased with cell growth. A precursor of the heme porphyrin, delta-[4-14C]aminolevulinic acid, was first incorporated (at accelerating rates) into acid-insoluble spore material at 180 min of germination, which appears to be the approximate time of organization of new mitochondria in these spores.

Aminolevulinic Acid↗
PubMedDate not supplied

Differences in the association between psychosocial work conditions and physical work load in female- and male-dominated occupations. MUSIC-Norrtälje Study Group.

This study investigated whether there is a relationship between high physical work load and adverse psychosocial work factors, and whether this relationship is different for women and men. Separate analyses for female registered nurses and assistant nurses were made because these are common occupations involving high physical and psychological demands. This study was part of the MUSIC-Norrtälje study, a population study with the overall aim of identifying risk factors for musculoskeletal disorders. The respondents, 1423 gainfully employed men and women, were randomly selected from the study population. The exposure assessments referred to a typical workday during the previous 12 months. Physical exposure was investigated by interview, psychosocial work factors by interview and questionnaire. For the women, but not the men, mainly routine work and a job strain situation, according to the model of Karasek and Theorell, increased the probability of having a high physical work load, assessed as a time-weighted average of energy expenditure in multiples of the resting metabolic rate. Results indicated that in female-dominated occupations, high physical work load might also imply adverse psychosocial conditions. A higher frequency of high physical work load and job strain was observed among assistant nurses compared with registered nurses. Covariance between physical and psychosocial demands makes it difficult to determine the relative influence of each in health problems. Results of the present study imply that this is a larger problem in studies of women than men.

Adult↗