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Biomedical subjects

W Klein

Publications and source records attributed to W Klein.

At least 379 records · Page 21Linked to original sources
PubMed1983

Role of calcium antagonists in the treatment of essential hypertension.

The calcium antagonists, diltiazem and nifedipine, are effective in mild-to-moderate chronic essential hypertension. The overall responder rate is 80%. Diastolic blood pressure is lowered by 10-15% at rest and during exercise. Systolic blood pressure is reduced only at rest. Heart rate may be unchanged by nifedipine and lowered by diltiazem. Both drugs lead to a decrease of peripheral resistance by 15-20% at rest and 30% during work. As a consequence of afterload reduction, cardiac output, stroke index, and stroke work index increased by 17, 21, and 7% with nifedipine and 34, 26, and 20% with diltiazem. During exercise, these changes are even more pronounced. However, pulmonary artery pressure and pulmonary vascular resistance are reduced only by nifedipine, not by diltiazem. Presumably due to this combined preload and afterload reduction, nifedipine therapy is associated with a reflex activation of the sympathetic nervous system in all cases, with an increase in norepinephrine plasma concentration and, sometimes, tachycardia. Diltiazem, however, has the advantage of being a potent blood pressure-lowering agent, with afterload reduction and increased stroke index, with less pronounced catecholamine increase, and without tachycardia. Side effects with this drug are rare, and long-term therapy is well tolerated.

Adult↗
PubMed1982

[Double-blind, placebo-controlled trial of propranolol vs celiprolol in stable effort angina: antianginal efficacy and side effects ].

A new cardioselective betablocker, celiprolol (C) in a dosage of 100 mg t.i.d. and propranolol (P) 40 mg t.i.d. were compared in 21 patients with angiographically documented obstructive coronary artery disease (stenosis of 75% or more in at least one vessel) and stable angina in a double-blind, placebo-controlled trial. C led to a significant reduction of anginal attacks and of nitroglycerin consumption (P less than 0.01), to a reduction of diastolic blood pressure (P less than 0.01) and heart rate (P less than 0.001) during rest and exercise. Under P, however, the number of anginal attacks and used nitroglycerin tablets was only slightly decreased, diastolic blood pressure remained constant and only heart rate was reduced significantly during rest and exercise (P less than 0.001). Total work performed was higher on drug treatment than on placebo (placebo: 238 +/- 21, celiprolol: 285 +/- 25, propranolol: 308 +/- 34 Watt/min). The difference against placebo is significant (p less than 0.01) with both drugs, but there is no difference between C and P. C led to a slight but constant decrease of triglycerides. Side effects were minor with both drugs.

Adrenergic beta-Antagonists↗
PubMed1982

Ketone-body utilization by homogenates of adult rat brain.

The regulation of ketone-body metabolism and the quantitative importance of ketone bodies as lipid precursors in adult rat brain has been studied in vitro. Utilization of ketone bodies and of pyruvate by homogenates of adult rat brain was measured and the distribution of 14C from [3-14C]ketone bodies among the metabolic products was analysed. The rate of ketone-body utilization was maximal in the presence of added Krebs-cycle intermediates and uncouplers of oxidative phosphorylation. The consumption of acetoacetate was faster than that of D-3-hydroxybutyrate, whereas, pyruvate produced twice as much acetyl-CoA as acetoacetate under optimal conditions. Millimolar concentrations of ATP in the presence of uncoupler lowered the consumption of ketone bodies but not of pyruvate. Indirect evidence is presented suggesting that ATP interferes specifically with the mitochondrial uptake of ketone bodies. Interconversion of ketone bodies and the accumulation of acid-soluble intermediates (mainly citrate and glutamate) accounted for the major part of ketone-body utilization, whereas only a small part was oxidized to CO2. Ketone bodies were not incorporated into lipids or protein. We conclude that adult rat-brain homogenates use ketone bodies exclusively for oxidative purposes.

2,4-Dinitrophenol↗
PubMed1982

Long-term fate of organochlorine xenobiotics in aquatic ecosystems. Distribution, residual behavior, and metabolism of hexachlorobenzene, pentachloronitrobenzene, and 4-chloroaniline in small experimental ponds.

Hexachlorobenzene (HCB), pentachloronitrobenzene (PCNB), and 4-chloroaniline (4-CA) were dosed into the water of small experimental ponds in Southern Germany. The average concentration of the chemicals in the pond water during the application period (4-6 weeks) was about 50 micrograms/liter. Chemical residue concentrations were determined in water, sediment, and flora and fauna species up to 166 weeks after application. The decrease of all chemicals in the water phase follows exponential functions and can be correlated to some extent with the physicochemical properties such as volatility from water and vapor pressure. Although chemically quite different, the residual behavior of the model compounds followed a similar pattern resulting in relatively high initial concentrations in biota and a slow buildup and subsequent decline of concentrations in the sediment. As to some fauna species (backswimmers and libellula larvae) and to sediment (0- to 20-cm layers), even 3 years after application, 14C residues of about 0.1 mg/kg could be found. In all analyzed flora species, however, no more residues could be measured in the new vegetation period after application. The amounts of the chemicals used did not cause detectable symptoms of poisoning over the investigation period. Anisols and azo compounds were found to be conversion products of pentachloronitrobenzene and 4-chloroaniline.

Adsorption↗
PubMed1982

[Alpha receptor blocking and cardial insufficiency].

Alpha receptor blocking drugs like Phentolamine, Phenoxybenzamine and Prazosin are potent vasodilators for the treatment of severe left ventricular failure refractory to treatment with digitalis and diuretics. 11 patients with congestive heart failure showed significant clinical and haemodynamic improvement after 4-week administration of 9 mg Prazosin/day. The cardiothoracic ratio was reduced significantly. Haemodynamically a marked decrease of peripheral vascular resistance, an increase of cardiac output, stroke volume and stroke work was noted. Heart rate and plasma catecholamines (dopamine, adrenaline, noradrenaline) showed no significant change. It is concluded that Prazosin exerts a beneficial effect in severe congestive heart failure after 4 week treatment without significant counterregulation to the vasodilatation.

Adrenergic alpha-Antagonists↗
PubMed1982

[Treatment of stable exercise angina with calcium blockers-a double-blind, placebo-controlled comparison of diltiazem and nifedipine].

In a placebo-controlled, randomized double-blind study, 43 out-patients with stable angina pectoris were treated for 2 months with a calcium-antagonist. 9 patients received a constant dose of 60 mg diltiazem t.i.d.; 12 patients underwent a dose increase to 90 mg t.i.d. after 4 weeks of treatment because of insufficient therapy response. In 5 patients 10 mg nifedipine t.i.d. was sufficient, 17 patients received 20 mg t.i.d. during the second part of the study. The patients were examined and subjected to symptom-limited ergometric tests at 2-week intervals. Under both medications, the frequency of anginal attacks decreased significantly; this was accompanied by a concomitant decrease of nitroglycerin consumption. During the tests, the time to occurrence of anginal complaints and thereby work capacity increased. ST-depression and ST-index were diminished. Heart rate, blood pressure and pressure-rate product did not change at rest or under exercise. There was no statistically significant difference between the two calcium-antagonists. Patients who showed satisfactory results under one of the two medications participated in an open, uncontrolled long-term trial and were treated with 60 mg or 90 mg diltiazem t.i.d. over a one-year period. There were no clinically remarkable events on changing from nifedipine to diltiazem. The monthly controls and the quarterly ergometric tests showed an unchanged efficacy of diltiazem. During the double-blind short-term treatment, the frequency of side effects was slightly lower under diltiazem than under nifedipine. Long-term treatment especially confirms the good tolerance of diltiazem.

Angina Pectoris↗
PubMed1981

Studies on 3-chloro-4-methyl-(4-14C)-7-hydroxycoumarin in rats.

The distribution, excretion and biotransformation of 3-chloro-4-methyl-(4-14C)-7-hydroxycoumarin [(14C) chlorferron] were studied in the rats after single oral administration. Male and female Wistar rats were given single oral doses of 0.5 and 20.0 mg/kg body weight of (14C) chlorferron and routes and rates of elimination of 14C activity were followed for 7 days. Following administration of 20 mg/kg, 96.74 +/- 3.68% and 94.98 +/- 6.15% of the dose were excreted by male and female rats, respectively. The excretion of total radioactivity after 0.5 mg/kg was significantly (P less than 0.05) higher in male rats (93.77 +/- 2.27%) as compared to female rats (87.23 +/- 1.96%). Approximately 80-90% of the excreted radioactivity was detected in urine. Analysis of urine showed no qualitative difference in the biotransformation pattern of (14C) chlorferron in male and female rats. (14C) chlorferron derived metabolites were excreted in both conjugated and unconjugated forms. After 7 days of dosing, very low concentrations of (14C) chlorferron derived residues were detected in different body tissues. No detectable sex difference in body distribution of radioactivity was observed. These results suggest that (14C) chlorferron is rapidly eliminated from the body and only small amounts are stored in the organs.

Animals↗
PubMed1981

Biotransformation and disposition of the coumaphos metabolite 3-chloro-4-methyl-(4-14C)-7-hydroxycoumarin in rats.

The biotransformation and disposition of 3-chloro-4-methyl-(4-14C)-7-hydroxycoumarin [(14C) chlorferron] were investigated in rats after single oral administration. Following administration of (14C) chlorferron at 0.5 and 20 mg/kg body weight to male rats, greater than 90% of the given dose was eliminated in the urine (77-84%) and faeces (7-15%) within 24 h. Low levels of (14C) chlorferron derived residues were detected in different organs of rats 7 days after dosing. Administration of (14C) chlorferron at 20 mg/kg allowed the isolation of three metabolites in the 24-h urine of male and female rats. Compounds tentatively identified were dechlorinated metabolites of chlorferron besides unchanged chlorferron. The majority of the metabolites were excreted in conjugated forms. The pattern of biotransformation of chlorferron was qualitatively similar in male and female rats. Comparative studies on the elimination and biodistribution of (14C) chlorferron and its parent compound (14C) coumaphos in male rats indicated rapid metabolism and faster elimination of chlorferron and its metabolites from the body than that of the parent compound.

Animals↗
PubMed1981

Osmium dependent argentaffin staining of lysosomes.

Lysosomes stain with the argentaffin reaction after fixation with glutaraldehyde followed by osmium tetroxide. The reaction works well both at the level of the light and electron microscope. Control experiments show that this argentaffinity is caused by reduced osmium tetroxide. No staining could be observed in freeze-dried material, in tissues fixed only with glutaraldehyde, or after bleaching of the sections with hydrogen peroxide solutions. In the electron microscopy, the population of lysosomes appears heterogeneous as related to the density of silver deposits over the organelles. No correlation is found between size and argentaffinity of lysosomes. X-ray microanalysis of sections from glutaraldehyde/osmium tetroxide fixed material reveals significantly higher amounts of osmium in lysosomes, as compared to other cell organelles (e.g. peroxisomes or mitochondria). A significant peak for silver is observed in lysosomes after treatment of the sections with ammoniacal silver solution, whereas the signal for osmium is reduced. Amounts of sulphur are too low to be detected in lysosomes. It is concluded that argentaffin staining of lysosomes is an osmium dependent reaction.

Animals↗