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Biomedical subjects

H Klein

Publications and source records attributed to H Klein.

At least 145 records · Page 8Linked to original sources

Comparison of catheter ablation using direct current energy versus radiofrequency: observations in 147 patients with supraventricular tachyarrhythmias.

We studied the follow-up of 147 patients who underwent catheter ablation because of drug resistant supraventricular tachyarrhythmias. Direct current (DC) ablation was performed in 116 patients, while 31 patients underwent radiofrequency (RF) ablation. In 101 patients (87%) with DC ablation and in 28 patients (90%) with RF ablation, complete atrioventricular (AV) block was achieved initially. Fifteen patients (13%) with DC ablation and three patients (11%) with RF ablation resumed AV conduction. Serious complications occurred in eight patients (7%) with DC ablation and in none of the patients with RF ablation. During the mean follow-up of 45 +/- 24 months, 13 patients died (11%) who underwent DC ablation; during the mean follow-up of 11 plus or minus 3 months, no patient died who had had RF ablation. Transcatheter ablation using DC or RF is an effective treatment in patients with drug resistant supraventricular arrhythmias, providing a beneficial long-term outcome including an improved quality of life. Although the risk of complications is low, this procedure should be reserved for patients with supraventricular arrhythmias who do not respond to conventional drug therapy.

Adult↗

Low dose alpha interferon treatment in chronic hepatitis B virus infection.

Fifty eight patients with chronic viral hepatitis B (HBV) were randomised in a prospectively controlled trial. Thirty patients were treated with 3 million units (MU) of interferon alfa-2b subcutaneously thrice weekly for four months. Twenty eight controls received no treatment. The follow up period after treatment was six months. Twenty eight treated patients and 27 controls completed the protocol. One woman in the treatment group showed a complete response, and eight other treated patients (32%) showed a partial response. Three patients in the control group (11%) lost hepatitis B e antigen and HBV-DNA spontaneously. This finding is statistically significant (p < 0.05). The elimination of HBV markers from the serum was associated with a return to normal of serum aminotransferase activities. Reactivation of hepatitis was not observed after seroconversion.

Adolescent↗

Evidence of androgen receptivity in the pathway of testicular descent in humans. A postnatal study.

The aim of this study was to detect androgen receptors in paratesticular tissue in an attempt to explain a possible mechanism of effect for hormone treatment in undescended testes. A total of 45 biopsies from the gubernaculum testis, musculus cremaster, processus vaginalis and subcutaneous fascia were taken from 13 patients aged 4 months-65 years. All biopsies were instantly frozen in liquid N2 in Norway and later transported to Hamburg for analysis. By using various procedures for stabilization and separation, cytosol was prepared which contained all primary intranuclear and extranuclear androgen receptors. R1881 was used as radioligand. The validity of the procedure was controlled with rat prostate. A full saturation analysis was obtained according to Scatchard. The musculus cremaster was the only structure examined which contained androgen receptors. The results indicate that endocrine treatment in undescended testes is effective in retractile testes only.

Adolescent↗

Bradykinin does not modulate the natriuretic response to atrial natriuretic factor in rats with aortocaval fistula.

Rats with aortocaval fistula, an experimental model of congestive heart failure (CHF), display two distinct patterns of sodium excretion: some rats develop marked sodium retention and worsening edema with urinary excretion of sodium (UNaV) < 200 microEq per 24 hours, i.e., uncompensated CHF, whereas in others sodium balance rapidly returns to normal (UNaV > 1,400 microEq per 24 hours), i.e., compensated CHF. Similar patterns of sodium excretion are found in patients with CHF. The mechanisms underlying these responses are not fully understood. The present study was designed to assess whether bradykinin plays a role in the compensatory response to CHF. Infusions of either 10 or 50 micrograms/kg per minute of synthetic atrial natriuretic factor (ANF)8-33 into sham-operated control animals produced significant increases in urine flow and fractional excretion of sodium (FENa). Infusions of ANF at the same doses into rats with compensated CHF increased FENa from 0.11 +/- 0.03% to a maximum of 6.10 +/- 1.30%, whereas the rise in FENa in animals with uncompensated CHF was significantly reduced (0.05 +/- 0.01% to 0.59 +/- 0.18%) compared with sham-operated controls (0.23 +/- 0.05% to 8.32 +/- 1.0%) or the group with compensated CHF. Treatment of the compensated rats with the bradykinin antagonist HOE-140 (D-Arg,[Hyp3, Thi5, D-Tic7, Oic8]-bradykinin) given at a rate of 100 nmol/kg per hour did not affect their renal response to the ANF. In addition, infusion of the bradykinin antagonist alone into compensated rats with aortocaval fistula had no significant effect on their basal urinary flow rate or sodium excretion during the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

The effects of 2-year treatment with the aminobisphosphonate alendronate on bone metabolism, bone histomorphometry, and bone strength in ovariectomized nonhuman primates.

This study examined the effect of 2 yr of treatment with the aminobisphosphonate alendronate (ALN) (0.05 or 0.25 mg/kg i.v. ALN every 2 wk) on estrogen deficiency bone loss and bone strength changes in ovariectomized (OVX) baboons (n = 7 per group) and the ALN mode of action at the tissue level. Biochemical markers of bone turnover increased in OVX animals and were maintained by ALN treatment at non-OVX levels (low dose) or below (high dose). 2 yr of treatment produced no cumulative effects on bone turnover markers. Histomorphometry showed a marked increase in cancellous bone remodeling in OVX animals. Activation frequency increased from 0.48 to 0.86 per yr (L5 vertebra), and the osteoid surfaces from 9 to 13.5% (P < 0.05). No changes were observed in eroded and osteoclast surfaces. ALN treatment decreased activation frequency and indices of bone formation to control levels (low dose) or below (high dose), did not change indices of mineralization, and increased bone mineral density (BMD) in the lumbar vertebrae (L2-L4) by 15% at 0.25 mg/kg (P < 0.05), relative to vehicle-treated animals. The mean strength of cancellous bone (L4) increased by 44% (low ALN dose) and 100% (high dose), compared with vehicle. The strength of individual bones correlated with the square of the L2-L4 BMD (r = 0.91, P < 0.0034). In conclusion, ALN treatment reversed the effects of ovariectomy on cancellous bone turnover and increased bone mass and bone strength in baboons.

Acid Phosphatase↗

Ultrastructural pathology of eccrine sweat gland epithelial cells in globoid cell leukodystrophy.

Three of four children were recognized by deficient beta-galactocerebrosidase activities as having globoid cell leukodystrophy inclusions in sweat gland epithelial cells, similar in ultrastructure to those seen in Schwann cells. This observation in globoid cell leukodystrophy emphasizes the need to include sweat gland epithelial cells in examinations of skin in globoid cell leukodystrophy, as well as in any neurometabolic disorder.

Biopsy↗

Attenuation of insulin actions in primary rat hepatocyte cultures by phenylarsine oxide.

Phenylarsine oxide (PAO), a trivalent arsenical which complexes vicinal dithiols, prevented the action of insulin in primary cultured adult rat hepatocytes. Simultaneous short-term treatment of 48-h old cells with insulin and 2 microM PAO resulted in complete attenuation of the insulin-dependent increase in the level of fructose 2,6-bisphosphate and the activation of phosphofructokinase 2, pyruvate kinase, glucokinase flux and glycolysis. Basal rates of glucose transport and glycolysis were not affected. PAO also abolished stimulation of glycogen synthesis and amino-acid transport and the decrease of glycogenolysis evoked by insulin. The 20-fold activation of the insulin receptor tyrosine kinase by insulin was, however, not reduced by PAO. The data suggest that in differentiated hepatocytes insulin signal transduction involves vicinal sulhydryls located at a post-receptor step.

Amino Acids↗

Regional differences in alcohol consumption and drinkers' attitudes toward drinking.

Based on a November 1986 national probability sample of American adults aged 21 and over (1,069 of whom were deemed "drinkers" on the basis of having consumed at least one alcoholic beverage in the 7 days prior to interview), this study examines whether region of residence influences drinkers' alcohol consumption and/or their perceptions of alcohol use. In addition to examining the main effects of the relationship between geographic region of residence and alcohol use, four measures of urbanization are also investigated for their influence on drinking. Results indicate that geographic region of residence makes little to no difference in people's alcohol use and has only a small impact on their drinking-related attitudes. By and large, urbanization and gender are not influential variables in these relationships.

Adult↗

The relationship between emotional state and alcohol consumption.

Based on a November 1986 national probability sample of 1,069 American drinkers (i.e., people who drank at least one alcoholic beverage in the past 7 days) aged 21 and over, this study investigates the relationship between 10 emotional states (i.e., happy, sad, calm, tense, stimulated, bored, irritable, romantic, festive, and lonely) and the amount of beer, wine, distilled spirits, and/or wine cooler consumed during respondents' last drinking episode. The results indicate that: (1) Although all of the mediating variables studied affected the relationship between affect and alcohol consumption, age appears to be the most influential of these variables; and (2) For each alcoholic beverage type, at least one emotional state was significantly related to amount consumed.

Adult↗

[The automatic implantable cardioverter-defibrillator for prevention of sudden heart death in children and adolescents].

Little experience exists with the automatic implantable cardioverter-defibrillator in the pediatric population. Since 1990, an automatic implantable cardioverter defibrillator was implanted in four young patients (mean age 15.8 years, mean body weight 53.3 kg) with life-threatening ventricular tachyarrhythmias at our institution. In three patients, a cardiac anomaly was evident (dilated cardiomyopathy, status post Rastelli operation for complex transposition of the great arteries, status post atrial switch for transposition of the great arteries), the last patient had a normal cardiac anatomy. Indications for implantation were resuscitation from documented hypotensive ventricular tachycardia in one patient and recurrent syncope of suspected cardiac origin in the remaining three patients. At preimplantation electrophysiological study, all four patients had inducible ventricular tachycardia and/or ventricular fibrillation. At implantation of the cardioverter defibrillator in the operating theatre, the ventricular tachyarrhythmias were again induced and terminated reliably by the device. After a mean follow-up of 13 months, three of the four patients had appropriate discharges without syncope or resuscitation. The automatic implantable cardioverter-defibrillator appears to be a feasible and effective therapy also in pediatric patients for prevention of sudden cardiac death due to ventricular tachyarrhythmias.

Adolescent↗

[Results and experiences of transvenous endocardial defibrillator therapy].

We studied the follow-up of 72 patients who underwent implantation of a transvenous defibrillation lead system (ELS) (Endotak, CPI). All patients had ventricular tachycardia (VT) or fibrillation (VF) refractory to antiarrhythmic drug therapy. There were 51 patients with coronary disease and 21 patients had non-ischemic VT/VF. ELS was combined with a subcutaneous patch in 52 patients and implanted alone ("single lead only") in 20 patients. 40 patients received the ELS combined with antitachycardia pacing devices (Ventak PRx, CPI; Cadence, Ventritex) and 32 patients with the Ventak P 1600 or P2, CPI. Implantation of the ELS was attempted in 80 patients and performed in 72 patients (90%): Intraoperatively, the mean defibrillation threshold (DTF) was > 25 Joule (J) in five patients and no reliable ELS position was possible to achieve in three patients. These eight patients underwent thoracotomy with epicardial patch implantation. The mean DFT was < or = 20 J in all 72 patients with a mean DFT of 14 +/- 8 J in VT patients and 17 +/- 10 J in VF patients. Two of 80 patients (3%) died: one patient died intraoperatively and one during the mean follow-up of 6 +/- 2 (< 1 to 18) months. Complications occurred in three patients (4%): Dislocation of the Endotak electrode was observed in two patients (3%) and one patient developed pneumothorax postoperatively. Our data show that the ELS is most suitable in the majority of patients with VT/VF and is the approach of first choice for cardioverter defibrillator implantation at the present time. However, despite a relatively low intra- and perioperative complication rate, this approach should not be performed in institutions without cardiac surgery.

Adolescent↗

Eicosanoid-mediated contractility of hepatic stellate cells.

To approach experimentally the problem of contractility, stellate cells from rats were isolated and grown on a flexible silicone rubber substrate. Increases or decreases in the number of wrinkles of the silicone membrane beneath the cells that were easily observable by microscopy was employed as semi-quantitative measure of stellate cell motility. Contraction of stellate cells accompanied by diminution of cell body size was induced by U46619 (a thromboxane A2 analogue) and prostaglandin (PG) F2 alpha. Wrinkle formation became detectable 1.5 min after addition of 2 microM-U46619 and reached its maximum 10-15 min later. The effect of PGF2 alpha was not so striking, but lasted for a longer period of time. On the other hand, dibutyryl cyclic AMP, Iloprost (a PGI2 analogue) and PGE2 led to the disappearance or decrease in the number of wrinkles, indicating relaxation of contracted stellate cells. For instance, after addition of 2 microM-Iloprost, 47, 75 and 82% of contracted stellate cells had relaxed within 5, 10 and 20 min respectively. Moreover, dibutyryl cyclic AMP induced disappearance of alpha-smooth muscle actin stress fibres. This response became recognizable 10 min after addition of dibutyryl cyclic AMP; 40 min later, 97% of stellate cells were devoid of stress fibres. Thus stellate cells are able to undergo reversible contraction in primary culture, and the contraction of these cells may be mediated by eicosanoids that can be produced within the liver.

Animals↗

The bisphosphonate, alendronate, prevents bone loss in ovariectomized baboons.

We examined the effect of the amino bisphosphonate alendronate, administered IV every 2 weeks at 0.05 and 0.25 mg/kg for 1 year, on bone loss and parameters related to bone metabolism in ovariectomized baboons. Relative to non-OVX animals, the OVX baboons experienced increased bone turnover, reflected in biochemical and histomorphometric measurements, and bone loss assessed by dual-beam absorptiometry in the lumbar spine, which was similar to changes observed in ovariectomized women. Alendronate treatment maintained all parameters of bone turnover at control (nonovariectomized) levels and prevented the bone loss in a dose-dependent manner. We concluded that ovariectomized baboons offer a suitable model for the bone changes observed in ovariectomized women and that these changes can be prevented by sustained administration of an appropriate dose of this aminobisphosphonate.

Acid Phosphatase↗

Role of mapping-guided surgery in patients with recurrent ventricular tachycardia.

To assess the value of ventricular tachycardia (VT) surgery 108 patients with recurrent episodes of VT were studied. There were 97 patients with coronary artery disease (group I) and 11 patients without coronary artery disease (group II). All patients in group I underwent subendocardial resection; 12 patients also underwent cryoablation. Cryoablation alone was performed in all patients in group II. During a mean follow-up period of 40 +/- 27 months, 29 patients (30%) in group I and two patients (18%) in group II died (p = 0.33). There were nine patients (9%) in group I and six patients (55%) in group II who had nonfatal recurrences of VT after surgery (p less than 0.01). In group I, there was a higher mortality rate among patients who had VT of posterolateral origin (14 of 31 patients; 45%) compared with 3 of 11 patients (28%) who had VT of anterolateral origin, 1 of 8 patients (12%) who had VT of inferoseptal, and 11 of 39 (29%) patients who had VT of anteroseptal origin. None of the eight patients with two distinct origins of VT died.

Adult↗

Surgical therapy for drug-refractory ventricular tachycardia: role of additional aneurysmectomy or bypass grafting.

To assess whether additional aneurysmectomy and/or bypass grafting influence prognosis we studied 97 patients with recurrent sustained monomorphic ventricular tachycardia after an old myocardial infarction. All patients underwent subendocardial resection due to drug-refractory ventricular tachycardia. There were 41 patients who had resection alone, 27 patients had resection and aneurysmectomy, 13 patients had resection and bypass grafting and the remaining 16 patients had resection with both, aneurysmectomy and bypass grafting. During the mean follow-up of 40 +/- 27 months 29 patients died (30%) (total mortality), 7 patients suddenly (7%) and 20 patients from cardiac causes (20%). There were no significant differences in total mortality between patients with resection alone (32%), patients with resection and aneurysmectomy (22%), patients with resection and bypass grafting (31%) and patients who had resection, aneurysmectomy and bypass grafting (38%). In addition, no significant differences were observed in the incidence of sudden death and nonfatal recurrences between patients with resection alone: sudden death 12%, recurrences 7%; patients with resection and aneurysmectomy: sudden death 0%, recurrences 19%; patients with resection and bypass grafting: sudden death 0%, recurrences 8%; and patients with resection, aneurysmectomy and bypass grafting: sudden death 13%, recurrences 0%. Postoperatively, left ventricular function improved in 56% of patients who had resection and aneurysmectomy compared to 17% of patients with resection alone, 31% of patients with resection and bypass grafting and 19% of patients who had resection, aneurysmectomy and bypass grafting. There is a low risk of sudden death and nonfatal recurrences after subendocardial resection. An influence of additional surgical approaches (aneurysmectomy or bypass grafting) on prognosis is not visible.

Adult↗