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Biomedical subjects

R Kramar

Publications and source records attributed to R Kramar.

At least 55 records · Page 3Linked to original sources
PubMed1984

Oligomycin toxicity in intact rats.

Intraperitoneal injection of oligomycin into the rat (0.5 mg per kg, corresponding to the LD33 dose) reduces the oxygen consumption by about 50%, whereas the arterial pO2 remains normal. The large extent of this decrease points to an involvement of liver and muscle tissue. Triiodothyronine pretreatment (3 doses of 0.075 mg/100 g body weight) is not able to prevent this effect. From the blood metabolites measured glucose, pyruvate and the parameters of lipid metabolism remain unchanged; only lactate is significantly increased, causing compensated metabolic acidosis. Heart rate, systolic blood pressure and electrocardiogram are essentially unchanged. Oliguria, reduced renal excretion of urea and increase of plasma urea also indicate a nephrotoxic action. The results are discussed in comparison with some effects of experimental uremia.

Animals↗
PubMed1984

Enhancement of choline dehydrogenase activity in rat liver mitochondria by clofibrate feeding.

Male rats were fed a diet containing 0.75% clofibrate. After three weeks, the specific activity of choline dehydrogenase of a liver mitochondrial fraction was more then doubled. However, the activity of two other NAD-independent flavoenzymes of the inner mitochondrial membrane namely proline and succinate dehydrogenases were not altered significantly. Thus changes of the inner mitochondrial membrane induced by clofibrate seem to be restricted to some particular enzymes.

Alcohol Oxidoreductases↗
PubMed1984

Enhancement of aldehyde dehydrogenase activity in rat liver by clofibrate feeding.

Treatment over a 3-week period of male rats with the hypolipidemic drug clofibrate results in a more than twofold increase of aldehyde dehydrogenase activity in liver homogenate and mitochondrial fraction. As a comparable rise is also found in the postmitochondrial fraction, it is suggested that not only the mitochondrial but also the microsomal moiety of aldehyde dehydrogenase is induced by clofibrate. Possibly the known enhancement of ethanol catabolism and some protective effect on the liver of clofibrate-treated animals is due, at least in part, to the increased acetaldehyde oxidation by liver aldehyde dehydrogenase.

Aldehyde Dehydrogenase↗
PubMed1983

[Continuous peritoneal dialysis in acute kidney failure].

The continuous ambulatory peritoneal dialysis (CAPD) has been proved as alternate method in the treatment of chronic end stage renal failure. This new form of continuous peritoneal dialysis can also be used in the treatment of acute renal failure; by CAPD-system you can reach a steady state in noncatabolic renal failure, in catabolic states the number of acute hemodialyses can be reduced. The main advantage of this continuous peritoneal dialysis is the simple practicability and the independence of machines.

Acute Kidney Injury↗
PubMed1982

[Variant angina non-invasive assessment of coronary morphology].

The predictability of coronary morphology was investigated in 28 patients with variant angina using clinical symptomatology, effectiveness of nifedipine an appropriate ECG changes. Using coronary angiography seven patients had shown normal or not significantly stenosed coronary arteries (group 1), 21 had significant coronary stenoses (greater than 70%) (group 2). Six patients of group 1 showed resting angina only, 11 out of group 2 had in addition exertional angina and 4 had to be assigned clinically to threatening infarct enlargement. Treatment with nifedipine was successful in 6 patients of group 1, however, only in 6 out of 17 patients in group 2. In no case did treatment with nifedipine lead to success in multiple vascular involvement. Normal control ECGs were present in 6 patients of group 1, a pathologic ECG with Q spikes or T inversions was seen in 20 patients of group 2. Results indicate good diagnostic accuracy for normal coronary vessels in the presence of angina at rest, effective treatment with nifedipine and normal control ECGs. Significant coronary stenoses may be assumed when angina at rest and during exertion, ineffective treatment with nifedipine and pathologic control ECGs are demonstrable. Using these parameters prediction of coronary morphology with non-invasive methods was possible in 14 of the 28 patients with variant angina.

Angina Pectoris, Variant↗
PubMed1981

Membranes of rat liver peroxisomes.

Membranes of liver peroxisomes from rats fed with clofibrate were purified in a discontinuous gradient using a zonal rotor. The preparation consists of round or oval vesicles mostly devoid of nucleoids with a diameter ranging from 70-700 nm; open sheets are found very infrequently. Mitochondrial profiles as well as vesicles containing cytochemically demonstrable glucose 6-phosphatase are scarce; accordingly, glucose 6-phosphatase is nearly undetectable biochemically. Monoamine oxidase is absent in peroxisomal membranes. Cytochrome b5 is found in a concentration of 0.3 nmoles/mg protein, an order of magnitude comparable to the content of endoplasmic reticulum membranes. Reduction of this cytochrome with palmitoyl-CoA is possible only after recombination of the membranes with the soluble peroxisomal matrix fraction.

Animals↗
PubMed1979

A characteristic membrane protein of liver peroxisomes inducible by clofibrate.

In sodium dodecyl sulfate polyacrylamide electrophoresis the membranes of rat liver peroxisomes show nine main protein bands (40 000--100 000 dalton); the 40 000-dalton polypeptide cannot be resolved from the membrane by deoxycholate. Treatment of the rats with clofibrate largely increases this protein and another one (about 80 000 dalton) in the peroxisomal but not in the endoplasmic reticulum membrane. Proliferation of peroxisomes seems to be connected with the insertion of specific proteins into the membrane.

Animals↗
PubMed1978

Beta-oxidation in peroxisomes of brown adipose tissue.

Peroxisomes and mitochondria from brown adipose tissue of the rat were separated by differential pelleting and isopycnic gradient centrifugation. Both fractions oxidized palmitoyl-CoA with comparable specific activities. Unlike the mitochondrial beta-oxidation the peroxisomal activity was not influenced by carbon monoxide. Peroxisomal beta-oxidation together with carnitine acetyl-transferase, which is also located in peroxisomes, might be involved in chemical thermogenesis by delivering acetyl groups to the mitochondria.

Adipose Tissue, Brown↗
PubMed1978

Catalase positive particles from pig lung. Biochemical preparations and morphological studies.

In pig lung tissue catalase positive particles (CPs) are abundant especially in type II pneumocytes and in Clara cells. In both cell types they occur as circular, oval or elongated membrane profiles surrounding a moderately electron dense matrix lacking a crystalline core. In Clara cells and in part of type II pneumocytes they are located as individual particles without any evident morphological relation to other cell organelles. In part of type II pneumocytes 5-8 particles are forming a group and their close relation to agranular endoplasmic reticulum cisterns is evident. The particles can be purified from lung homogenates by fractionated pelleting and subsequent rate sedimentation in a sucrose gradient using a zonal rotor. The catalase rich fraction bands in the middle of the gradient whereas cytochrome oxidase and part of the acid phosphatase sediments at its heavy end. A second part of acid phosphatase stays at the light end of the gradient and--according to morphological control--seems to correspond to lamellar bodies of the type II pneumocytes. The purified catalase positive particles do not contain hydroxyacid and D-aminoacid oxidases thought to be characteristic H2O2 producing enzymes of peroxisomal systems. The buoyant density of the particles (d = 1.195 g/cm3) is lower than that of liver peroxisomes. Cytochemical controls of the peroxisomal pellets exhibit the particles partly uniformly filled with reaction product, partly irregularly stained.

Acid Phosphatase↗
PubMed1978

[Recurrence of pseudotumour cerebri (intracranial hypertension) after renal transplantation (author's transl)].

The case report is presented of a 24-year-old male who developed the clinical signs and syptoms of pseudotumour cerebri (intracranial hypertension) twice during the course of protracted rejection 1 and 4 months after renal transplantation. Clinically, headache, nausea, hypertensive crisis and, finally, severe coma with an acute mid-brain syndrome was observed. Neurologically a mild left-sided hemiparesis was found on the second occasion. Examination of the fundi revealed bilateral papilloedema. Electroencephalograms showed pathological changes of a diffuse nature, later followed by abnormal delta range activity in the right frontotemporal projection. The withdrawal of corticosteroid therapy may have been responsible for the pseudotumour cerebri in this case.

Adult↗
PubMed1978

Preparation of peroxisomes from carp liver by zonal rotor density gradient centrifugation.

Peroxisomes from carp liver can be separated by isopycnic density gradient centrifugation in sucrose. Without reaching complete sedimentation equilibrium, the purification by this method is quite successful. There is a 40-fold enrichment of catalase, the peroxisomal marker, with a total yield of 27%. No pretreatment of animals is necessary for separation from lysosomes, which, besides high fragility, show lower buoyant densities than peroxisomes. The enzyme content of carp liver peroxisomes is similar to that of rat liver, with the exception of alpha-glycerophosphate dehydrogenase, which in this tissue is a completely soluble cytoplasmic enzyme. Total activities are much lower than in the rat, for the characteristic peroxisomal oxidases the difference being in the range of one order of magnitude.

Alcohol Oxidoreductases↗
PubMed1976

Enzymic and morphological studies on catalase positive particles from brown fat of cold adapted rats.

Brown adipose tissue of normal and cold-adapted adult rats has been investigated morphologically and cytochemically. In thin-sections catalase-positive particles appear as circular, oval or elongated profiles lying either as single particles or forming groups. Biochemical studies on peroxisomal enzymes show an increase of catalase activity to the tenfold amount after cold adaptation. The tissue is devoid of D-aminoacid oxidase and glycolate oxidase, while low activities of middle-chain-alpha-hydroxyacid oxidases could be detected. The catalase-positive particles were purified by differential and is lower than that of the liver peroxisomes. Enzymic investigations of the fractions render it probably that particles contain carnitine acetyltransferase, whereas they are lacking NAD-dependent glycerophosphate dehydrogenase. The pellets derived from the gradient centrifugation have been checked morphologically for purity. After performing DAB-cytochemistry for identification of the peroxidatic activity of catalase, most of the particles were shown to be structurally intact and homogeneously filled with reaction product.

Adipose Tissue, Brown↗
PubMed1976

Effect of clofibrate application on morphology and enzyme content of liver peroxisomes.

Male albino rats (Sprague Dawley) were fed for 2-6 weeks on a diet containing 0.75% clofibrate. Liver cell fractions obtained from these animals were assayed for peroxisomal enzymes. In the cell homogenate the catalase activity was doubled, whereas the activity of urate oxidase was found to be only slightly depressed. The activity of carnitine acetyltransferase increased several times. In liver peroxisomes purified by isopycnic gradient centrifugation the specific activity of urate oxidase decreased appreciably showing that peroxisomes formed under the proliferative influence of clofibrate are not only modified with respect to their morphological characteristics but also to their enzymic equipment. This is also obvious from the changes in peroxisomal carnitine acetyltransferase activity which was enhanced by clofibrate to more than the fivefold amount. In purified mitochondria this enzyme was even more active: clofibrate advances both, the peroxisomal and the mitochondrial moiety of carnitine acetyltransferase. Morphological and cytochemical studies showed an increase in the number of microbodies and as compared to the controls microbodies were lying in groups more frequently. Small particles located closely adjacent to "normal" sized peroxisomes were found particularly after short feeding periods. While the number of coreless microbodies increased studies gave no clear evidence for an increase in marked shape irregularities of the peroxisomes.

Animals↗