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Biomedical subjects

J Kaiser

Publications and source records attributed to J Kaiser.

At least 199 records · Page 11Linked to original sources
PubMed1991

Catheter-induced tricuspid regurgitation. Incidence and clinical significance.

The incidence and severity of catheter-induced tricuspid regurgitation has not been studied extensively. Given the frequency with which right heart catheters are employed to measure cardiac output, it is important to know whether the severity of catheter-induced tricuspid regurgitation is sufficient to invalidate the measurement of thermodilution cardiac output. Accordingly, the purpose of the present prospective study was to determine the incidence and severity of catheter-induced tricuspid regurgitation in 25 men (mean age, 58.1 +/- 1.4 years) using Doppler ultrasound. The tricuspid valve was interrogated from two orthogonal views using pulsed-wave and color flow Doppler, either in the presence or absence of a 7-French catheter across the tricuspid valve. The severity of catheter-induced tricuspid regurgitation was graded semiquantitatively using a validated scoring system. Pulsed-wave Doppler studies showed that the incidence of catheter-induced tricuspid regurgitation was 48 percent, and that the average tricuspid regurgitation score increased from 0.41 +/- 0.16 to 0.61 +/- 0.17 (p less than 0.01). Color flow Doppler studies showed similar findings. Further, the incidence of catheter-induced tricuspid regurgitation was not related to the patient's underlying hemodynamic status or right ventricular geometry. In conclusion, this study shows for the first time that the quantitative extent of catheter-induced tricuspid regurgitation is small, and is therefore unlikely to be important clinically, particularly with regard to the assessment of thermodilution cardiac output.

Cardiac Catheterization↗
PubMed1991

Prospective and retrospective time estimation.

30 students, when performing a task that required listening to 19 sentences for 150 sec., overestimated the duration of the task less in the prospective condition than in the retrospective one (46 sec. vs 85 sec.).

Adult↗
PubMed1991

[Experiences with intraoperative radiotherapy in gastric carcinoma (Berlin method)].

The aim of our pilot study is to determine whether intraoperative radiotherapy in gastric cancer cannot only prevent a local relapse but also improve the survival rate. Since November 1987, 26 patients with resectable gastric cancer were irradiated intraoperatively with the linear accelerator using fast electrons (single dose: 12 to 16 Gy). Percutaneous radiotherapy was performed postoperatively with 24 to 38 Gy (4 x 2 Gy per week). For intraoperative and percutaneous radiotherapy the target absorbed dose was selected in a way that their combined effect on the tumor was approximately equivalent to that of a total dose of 60 Gy in the usual fractionating. Up to now, the median survival time for stage III patients (UICC 1987) has been twelve months. In five patients who died of a relapse or of peritoneal carcinosis, histologic evaluation revealed in every case a diffuse tumor type according to Lauren-classification. All relapses occurred within the first eight months. The two-year survival rate according to Kaplan-Meier is 67% for stage III. Advanced resectable gastric cancer of the intestinal tumor type seems to profit from adjuvant intraoperative radiotherapy. The results warrant further research within the framework of a prospective randomized multicenter study.

Adenocarcinoma↗
PubMed1990

High lumbar disc degeneration. Incidence and etiology.

Three hundred seventy-nine consecutive magnetic resonance images (MRIs) with dual-echo images of the entire lumbar spine were reviewed by the authors. All 379 patients presented with back pain and/or leg pain; they were interviewed and examined. Pain drawings were completed by all. There were 42 patients (11.1%) with disc pathologies involving T12-L1, L1-2, and/or L2-3 levels. Six patients (1.6%) had isolated disc degeneration and/or herniations limited only to these high lumbar segments. The remaining 36 patients had degenerative changes of the higher discs with variable involvement of the lower lumbar discs. Out of 12 spondylolistheses of L5 on S1, 7 had high disc pathologies at one or more levels presenting as skipped lesions; more severe high disc lesions were noted in Grade II slips. Isolated high disc degeneration is often associated with pre-existing abnormalities such as end-plate defects, Scheuermann's disease, limbus vertebra, and so forth, and stressful cumulative work activities such as in construction workers, airplane mechanics, and so forth. High disc degeneration was noted above or below previous fractures. High disc involvement with diffuse changes in lower lumbar spine was more commonly found in ascending fashion in older age groups, and in patients who have had previous lower lumbar spine surgeries, prior fusions in particular. Our findings suggest that altered mechanics are associated with the high lumbar disc pathologies.

Adult↗
PubMed1990

Cross-sectional echocardiographic characterization of atelectatic lung segments. Differentiation from extracardiac tumors.

This report describes a unique series of patients who, during routine cross-sectional echocardiographic examination, were each noted to have a large echo-dense extracardiac mass adherent to the lateral aspect of the left ventricle. While this echo-dense mass was considered initially to represent an extracardiac tumor, this mass was shown subsequently to be an atelectatic segment of the left lower lobe of the lung. The salient echocardiographic findings that were considered to be helpful in terms of differentiating these adherent pulmonary atelectatic lung segments were that the lung segments always occurred in the presence of a moderate to large left pleural effusion; in real-time examination, the atelectatic lung masses generally appeared solid, as opposed to cystic, with a characteristic brightly reflective ground-glass appearance; there was never any evidence of extrinsic compression of the heart by the lung mass.

Aged↗
PubMed1989

Cardiac arrhythmias are ameliorated by local inhibition of angiotensin formation and bradykinin degradation with the converting-enzyme inhibitor ramipril.

We investigated the influence of the angiotensin-converting enzyme (ACE) inhibitor ramipril on cardiac arrhythmias in guinea pigs and rats. Ramiprilat, the active moiety of ramipril, did not influence action potentials of isolated guinea-pig papillary muscle or rabbit sinus node, thereby excluding cellular electrophysiological evidence of anti-arrhythmic properties. Ramipril protected against cardiac arrhythmias induced by digoxin infusion in guinea pigs. This effect was comparable with that of lidocaine. In isolated perfused ischemic working rat hearts, angiotensin (ANG) I (3 x 10(-9) M/l) and ANG II (1 x 10(-9) M/l) aggravated reperfusion arrhythmias, accompanied by deterioration of cardiodynamic and metabolic events. Bradykinin (BK) (1 x 10(-10)-1 x 10(-8) M/l), in contrast, protected against reperfusion arrhythmias, which corresponded to an increase in energy-rich phosphates and glycogen stores and a decrease in lactate levels in myocardial tissue. Identical changes were seen in hearts from rats pretreated with ramipril (1 mg/kg PO) or perfused with ramiprilat (2.58 x 10(-7)-2.58 x 10(-5) M/l). Local ACE inhibition in these ischemic hearts antagonized ANG I but not ANG II effects and enhanced BK effects. The BK antagonist D-Arg-(Hyp2, Thi5,8, D-Phe7)BK abolished the beneficial effects of BK, ramipril, and ramiprilat. Increased concentrations of BK or ramiprilat were able to reverse the antagonism. The antiarrhythmic agent nicainoprol, a fast-sodium-channel blocking drug (class Ib), also protected isolated rat hearts against reperfusion arrhythmias, but was without beneficial effects on cardiac hemodynamics and biochemical parameters, in contrast to the ACE inhibitor. These results suggest that the beneficial effects of the ACE inhibitor ramipril on digoxin and reperfusion arrhythmias are not mediated by their direct actions on ionic channels in the cell membrane. It seems that other factors are responsible for its beneficial effects on reperfusion arrhythmias, cardiac function, and metabolism, which are associated with a reduction in ANG II generation and BK degradation by local ACE inhibition in the heart.

Action Potentials↗
PubMed1989

Reversion of mitral valve preclosure in acute aortic insufficiency secondary to infective endocarditis.

A 59-year-old man presented with culture-negative endocarditis. Serial echocardiographic/Doppler studies disclosed progressive aortic insufficiency with resultant premature closure of the mitral valve. At the time the patient developed PMVC he was considered for emergent aortic valve replacement; ultimately, however, he was deemed inoperable because of his underlying medical problems. Surprisingly, the patient gradually improved on antibiotic therapy alone, with subsequent hemodynamic stabilization and reversion of the PMVC. This case represents the first description of reversion of PMVC in a medically treated patient with severe aortic insufficiency secondary to infective endocarditis, and underscores the importance of basing management decisions concerning aortic valve replacement in infective endocarditis upon the entire constellation of clinical findings rather than a single echocardiographic sign.

Aortic Valve Insufficiency↗
PubMed1989

[Congestive heart failure in rickets caused by vitamin D deficiency].

We describe a case of a three and half month old infant presenting with a congestive heart failure due to hypocalcemic cardiomyopathy. Vitamin D deficiency rickets was found to be the cause for the hypocalcemia. The heart failure responded promptly to adequate Calcium therapy accompanied by usual anticongestive therapy.

Cardiomyopathy, Dilated↗
PubMed1988

Evidence for a distinct Ca2+ antagonist receptor for the novel benzothiazinone compound HOE 166.

The pharmacological and binding properties of the novel enantiomerically pure benzothiazinone (R)-(+)-3,4-dihydro-2-isopropyl-4-methyl-2-[2-[4-[4-[2-(3,4,5-tri- methoxyphenyl)-ethyl]-piperazinyl]-butoxyl-phenyl]-2H-1,4- benzothiazine-3-one dihydrochloride (HOE 166), are described. HOE 166 stereoselectively inhibited KCl-but not noradrenaline-induced contractions of guinea-pig pulmonary arteries, rabbit aorta, rat mesenteric artery preparations and k-strophantin-induced enhancement of guinea-pig papillary muscle contraction in a dose-dependent manner. KCl-induced smooth muscle contraction was inhibited by HOE 166 with IC50-values of approximately 70 nM (5-11 times less potent than nifedipine, 2-16 times more potent than verapamil), the respective S-(-)-enantiomer being approximately 10-fold less potent. HOE 166 decreased the upstroke velocity of the slow action potential in partially depolarized guinea-pig papillary muscle at similar concentrations than nifedipine. To investigate possible interactions with the calcium channel, HOE 166 and its S-(-)-enantiomer were characterized by radioligand binding studies in heart, brain and skeletal muscle transverse-tubule membranes. HOE 166 was a 4-15 times more potent inhibitor of reversible (+)-[3H]PN200-110, (-)-[3H]desmethoxyverapamil and d-cis [3H]diltiazem binding compared to its pharmacologically less active (S)-(-)-enantiomer, with IC50 values in the low nanomolar range. Extensive equilibrium and kinetic studies suggest that HOE 166 exerts its Ca2+-antagonistic effect by binding to a Ca2+-channel-associated drug receptor which is distinct from the 1,4-dihydropyridine, phenylalkylamine or benzothiazepine-selective domain. This HOE 166-selective site is, however, allosterically linked to the other sites of the Ca2+ antagonist receptor complex. We conclude that HOE 166 is a novel calcium antagonist.

Action Potentials↗
PubMed1988

Effect of monensin on receptor recycling during continuous endocytosis of asialoorosomucoid.

The binding of asialoglycoproteins to their liver cell receptor results in internalization of the ligand-receptor complex. These complexes rapidly appear in intracellular compartments termed endosomes whose acidification results in ligand-receptor dissociation. Ligand and receptor subsequently segregate: ligand is transported to lysosomes and is degraded while receptor recycles to the cell surface. The proton ionophore monensin prevents acidification of endosomes and reversibly inhibits this acid-dependent dissociation of ligand from receptor. The present study determined the effect of monensin treatment of short-term cultured rat hepatocytes on cell-surface-receptor content, determined both by their binding activity and immunologically, following continuous endocytosis of asialoorosomucoid. Inclusion of 5 microM monensin in the incubation medium reduced the number of immunologically detectable cell-surface receptors by 20% in the absence of ligand. During continuous endocytosis of asialoorosomucoid, inclusion of monensin resulted in a 30-40% reduction of cell-surface receptor detectable either by ligand binding or immunologically. These results suggest that the reduced liver-cell-surface content of receptor in monensin is due to intracellular trapping of ligand-receptor complexes. The reduction of surface receptor during monensin incubation in the absence of ligand suggests that "constitutive recycling" of plasma membrane components also requires intracellular acidification.

Animals↗
PubMed1988

Catheter infection. A comparison of two catheter maintenance techniques.

Incidence of catheter-related infections was studied using two techniques: changing catheters over a guide-wire or placing a new catheter at a new site every 3 days. Patients were randomized into two groups: Group 1 (new site) and Group 2 (guide-wire). Of the 105 catheterization sites (20 arterial and 85 central lines) in patients of Group 1, none were considered infected (i.e., having 15 or more colonies at the time of semi-quantitative microbiology analysis and clinical signs of infection at the catheter site). Of the 274 catheterization sites (56 arterial and 218 central) of patients of Group 2, eight (2.9%) were infected (chi 2 = 1.89, p greater than 0.05). Colonization (15 or more cultures without clinical signs of infection) occurred in three of 105 (2.9%) and in four of 274 (1.5%) of the catheterization sites of Groups 1 and 2, respectively (chi 2 = 0.23, p greater than 0.05). Study results indicate no significant difference in infection or colonization rates between the two methods of catheter replacement.

Adolescent↗
PubMed1988

Normal magnetic resonance imaging with abnormal discography.

In degenerative lumbar spine disease, recent studies have supported the clinical usefulness of discography, especially when used with computed tomography (CT) scanning. The role and capabilities of magnetic resonance imaging (MRI) scanning are currently evolving and being defined. This study reviews a series of patients with prolonged disabling symptoms who had normal MRI scans and abnormal discography. Discograms and discogram-CT scans may at times allow detection of clinically correlative and significant pathology (usually annular disruptions) not suggested by MRI scanning. This fact should be considered in patients with normal MRI scanning and continuing unexplained symptomatology.

Adult↗
PubMed1987

[Sedation in ambulatory BERA (brainstem electric response audiometry) studies in childhood].

We use BERA to determine the hearing threshold of children. This examination is most of the time performed on outpatients and often combined with a minor surgery. That's the reason why a sedation has to fulfill following conditions: 1. a quick, non-traumatic induction of anaesthesia--normally--without premedication; 2. an anesthesia deep enough to enable us to carry out a minor surgery as well as to get the best reliable BERA results; 3. a short period of wake-up as the patient should leave the hospital as soon as possible. In short, we got the best results first using Halothane as inhalant for the minor surgery and continuing with Midazolam as i.v. sedative for BERA examination.

Anesthesia, General↗
PubMed1984

Monocytes direct T lymphocyte stimulation of human peripheral blood granulocyte-macrophage colony formation.

The committed granulocyte-macrophage progenitor cell (or colony-forming unit, CFU-GM) differentiates in vitro under the influence of the soluble glycoprotein factor(s) termed colony stimulating activity (GM-CSA), which can be derived from several cellular sources, including normal human peripheral blood mononuclear cells (PBMNC). We have investigated the respective roles of the monocyte and T lymphocyte components of PBMNC in generating GM-CSA using as an assay CFU-GM colony formation by purified peripheral blood null cells. Highly purified unstimulated T-lymphocytes did not themselves stimulate null cell CFU-GM colony formation, but when monocytes were also included, large numbers of colonies were observed, far greater than those stimulated by monocytes alone. This synergism was independent of HLA phenotype, occurring with T-lymphocyte and monocyte fractions from unrelated donors. Media conditioned by unstimulated purified monocytes promoted CFU-GM colonies from null cells only in the presence of T-lymphocytes, suggesting that monocytes produce a factor directing the synthesis and/or release of GM-CSA by T cells.

Cells, Cultured↗
PubMed1984

Hoe 263, a new substance with calcium channel antagonistic activity.

Hoe 263 inhibited the contraction of the potassium-depolarized pulmonary artery of the guinea pig. In this experiment it was slightly more active than verapamil. The calcium uptake of the potassium-depolarized pulmonary artery was inhibited by Hoe 263 more effectively than by prenylamine. The upstroke velocity of the potassium-depolarized papillary muscle of the guinea pig was depressed with similar concentrations of Hoe 263 and verapamil. In the (3H)-nitrendipine binding test, Hoe 263 was effective at similar concentrations as prenylamine and verapamil. The positive inotropic effect of K-strophanthin was depressed by Hoe 263 at concentrations which were comparable with those necessary for verapamil.

Animals↗
PubMed1984

Cardiovascular and antihypertensive activities of the novel non-sulfhydryl converting enzyme inhibitor 2-[N-[(S)-1-ethoxycarbonyl-3-phenylpropyl]-L-alanyl]-(1S,3S,5S)-2- azabicyclo[3.3.0]octane-3-carboxylic acid (Hoe 498).

The cardiovascular and antihypertensive activities of the novel orally active non-sulfhydryl converting enzyme (CE) inhibitor 2-[N-[(S)-1-Ethoxycarbonyl-3-phenyl-propyl]-L-alanyl] -(1S,3S,5S)-2-azabicyclo[3.3.0]octane-3-carboxylic acid (Hoe 498) were evaluated in several experimental preparations. The hemodynamic profile of Hoe 498 in anesthetized animals was characterized by a reduction in systemic blood pressure which was associated with a decrease in total peripheral and renal vascular resistance. These effects were enhanced upon sodium depletion. In conscious normotensive rats a single oral administration of Hoe 498 reduced systemic blood pressure for more than 5 h. The development of acute renovascular hypertension in anesthetized rats was prevented by oral pretreatment with Hoe 498. In conscious rats with renovascular hypertension (two-kidney, one clip) single oral doses of Hoe 498 induced a long lasting antihypertensive effect. Chronic oral treatment of spontaneously hypertensive rats with Hoe 498 lowered arterial blood pressure more effectively than enalapril. The threshold antihypertensive dose for Hoe 498 was 0.01 mg/kg/d, for enalapril 1 mg/kg/d. In conscious hypertensive dogs (two-kidney, two wrapped) Hoe 498 at a single oral dose of 10 mg/kg reduced systemic blood pressure for more than 6 h. Oral administration of Hoe 498 in a dose of 1 mg/kg/d for 5 d normalized systemic blood pressure in conscious hypertensive dogs. These findings demonstrate that in various models of experimental hypertension the novel orally active converting enzyme inhibitor Hoe 498 exerts marked cardiovascular and potent prolonged antihypertensive activities, which merit exploration with respect to possible therapeutic benefits.

Anesthesia↗
PubMed1984

Quantitative analysis of the role of accessory cells in the development of human blood BFU-E-derived erythroid colonies.

A simplified method for the purification of human peripheral blood erythroid progenitor cells (BFU-E) using standard immunological techniques is described. Following removal of platelets, erythrocytes, nylon-wool-adherent cells, and sheep erythrocyte rosette-forming cells (RFC), BFU-E are routinely concentrated tenfold in the null cell fraction. Null cells plated at low density in erythroid cell cultures containing optimal amounts of methylcellulose, erythropoietin, and fetal calf serum did not give rise to spontaneous erythroid colonies. Coculture of null cells with highly purified, autologous RFC at a ratio of 1:25 yielded well-hemoglobinized erythroid colonies which were noticeably smaller than those found in cultures containing unfractionated peripheral blood mononuclear cells. However, further addition of very low numbers of purified adherent cells to null plus RFC dramatically increased the total hemoglobin content as well as the size and number of BFU-E-derived erythroid colonies. Addition of adherent cells alone to null cells had virtually no effect. Under conditions of optimal stimulation by adherent cells and RFC, the number of erythroid bursts was linearly related to null cells plated over an eightfold range. The synergism exhibited between adherent cells and RFC was not restricted by mismatched histocompatibility antigens. This system should be generally useful in quantitating the roles of more highly purified cellular and molecular populations in human erythropoiesis.

Cell Adhesion↗