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Biomedical subjects

W Münster

Publications and source records attributed to W Münster.

At least 19 recordsLinked to original sources
PubMed1992

Effects of alloxan and ninhydrin on mitochondrial Ca2+ transport.

Alloxan at millimolar concentrations slightly inhibited the velocity of Ca2+ uptake by isolated rat liver mitochondria irrespective of the free Ca2+ concentration between 1 and 10 microM and was an effective concentration-dependent stimulator of mitochondrial Ca2+ efflux. Ninhydrin also slightly inhibited the velocity of mitochondrial Ca2+ uptake but only at free Ca2+ concentrations above 5 microM. However, ninhydrin was a strong stimulator of mitochondrial Ca2+ efflux even at micromolar concentrations, 10-50 times more potent than alloxan. The mitochondrial membrane potential was reduced 10-20% at most by alloxan and ninhydrin. Alloxan and ninhydrin also stimulated Ca2+ efflux from isolated permeabilized liver cells. When isolated intact liver cells had been pre-incubated with alloxan or ninhydrin before permeabilization of the cells the ability of spermine to induce mitochondrial Ca2+ uptake was abolished. Glucose provided the typical protection against the effects of alloxan on mitochondrial Ca2+ transport only in experiments with intact cells but not in experiments with permeabilized cells or isolated mitochondria. Therefore glucose protection is apparently due to inhibition of alloxan uptake into the cell. Glucose provided no protection against effects of ninhydrin under any of the experimental conditions. Thus both alloxan and ninhydrin are potent stimulators of Ca2+ efflux by isolated mitochondria but very weak inhibitors of the velocity of mitochondrial Ca2+ uptake. The direct effects of ninhydrin on mitochondrial Ca2+ efflux may contribute to the cytotoxic action of this agent whereas the direct effects of alloxan on mitochondrial Ca2+ transport require concentrations which are too high to be of relevance for the induction of the typical pancreatic B-cell toxic effects of alloxan. However, the effects on mitochondrial Ca2+ transport during incubation of intact cells which may result from the generation of cytotoxic intermediates during alloxan xenobiotic metabolism may well contribute to the pancreatic B-cell toxic effect of alloxan.

Alloxan↗
PubMed1992

Dual effect of spermine on mitochondrial Ca2+ transport.

1. A dual effect of the polyamine spermine on Ca2+ uptake by isolated rat liver, brain and heart mitochondria could be demonstrated by using a high-resolution system for studying mitochondrial Ca2+ transport. Depending on the experimental situation, spermine had an inhibiting or accelerating effects on mitochondrial Ca(2+)-uptake rate, but invariably increased the mitochondrial Ca2+ accumulation. 2. Both effects were concentration-dependent and clearly discernible on the basis of their different kinetic characteristics. For mitochondria from all three tissues the half-maximally effective concentration for inhibition of the initial rate of Ca2+ uptake was approx. 180 microM, whereas that for the subsequent stimulation of Ca2+ accumulation was approx. 50 microM. 3. Acceleration of the initial uptake rate could be seen when the mitochondria were preloaded with spermine during a 2 min preincubation period and thereafter incubated in a medium without spermine. 4. When such spermine-preloaded mitochondria were incubated in a spermine-containing medium, the increase in Ca(2+)-accumulation capacity was maintained in spite of an unchanged rate of Ca2+ uptake. 5. Mg2+ interacted with the effects of spermine in a differential manner, enhancing the initial inhibition of the rate of mitochondrial Ca2+ uptake and diminishing the subsequent stimulation of mitochondrial Ca2+ accumulation. 6. This dual effect of spermine on mitochondrial Ca2+ transport resolves the apparent paradox that a polycationic compound can act as a stimulator of Ca2+ uptake.

Animals↗
PubMed1992

[Therapeutic embolization of pulmonary arteriovenous malformations].

It is reported on the practicability and the results of therapeutic embolizations in 7 patients with pulmonary av-malformations. The embolizations were carried out by detachable balloons. In all cases there were immediate and well-defined occlusions. In direct fistulas the embolization represents a curative procedure. However, in cases of angiomatous malformations with slow flow character, only a reduction of shunt or decreasing of size is obtained.

Angiography↗
PubMed1990

[Imaging procedures in diagnosis of variceal hemorrhage].

Imaging procedures in patients suffering from portal hypertension and the problems arising from this condition are limited to the demonstration of the morphology of the collateral circulation towards the superior and the inferior vena cava. Imaging is essential prior to elective and emergency treatment of bleeding varices. Non-invasive and invasive imaging procedures are available. Acute hemorrhage of varices usually can not be demonstrated with any of the methods. Important is the preoperative evaluation of the portal system and the angiographic demonstration of the anatomy.

Diagnostic Imaging↗
PubMed1989

[Changing trends in percutaneous and endoscopic bile duct drainage].

Analysis of 1,104 non-surgical biliary drainages (600 ERCD, 531 PTCD) from 1983 to 1988 concerning changing frequency, indications and success rates. With a continuous increase of the total numbers, the fraction of percutaneous-transhepatic drainages has decreased to 28%. With increasing degree of difficulty and risk PTCD (90.9% success) is indicated primarily in case of impossible ERCD (85.9% success) and hilar benign and malign biliary obstruction for temporary or permanent biliary drainage. Both methods are complementary and are increasingly used for combined palliative drainage.

Adolescent↗
PubMed1989

[Embolization therapy using detachable balloons].

Report on the application of a new (valve equipped) detachable balloon for percutaneous transvasal embolization therapy in 372 patients with (noncerebral) curative preoperative and palliative indications.

Embolization, Therapeutic↗
PubMed1989

[A double-blind randomized comparative study of iopromide and amidotrizoate in the angiocardiography of infants and young children with congenital heart defects].

For 50 sucklings and small infants with cyanotic and acyanotic heart defects the non-ionic contrast medium Iopromide was tested against the ionic contrast medium Amidotrizoate in angiography. With consideration to the applied method the tested cardiospecific enzymes (CK MB, alpha-HBDH, lactate) as well as hematocrit, oxygen content of central venous blood, heart rate, systolic pressures in both ventricles and ECG showed no significant differences. The different end-diastolic pressures in both ventricles and the average pressure in the right atrium, however, showed the cardiotoxicity of Amidotrizoate. Conclusively the use of Iopromide is demanded for infants, small infants and sucklings.

Angiocardiography↗
PubMed1989

[Animal experimental studies on the microcirculation of ionic and nonionic x-ray contrast media].

In vivo microscopic (video) investigations on the variability of flow conditions in the myocardium and intestines of anaesthesized normal tension rats after application of various ionic and non-ionic contrast media (Amidotrizoate, Ioxaglate, Iopromide, Iohexol, Iotrolan). Amidotrizoate causes heterogeneous microperfusion and functional shunt vessels (distribution disorder) with the typical symptoms of disturbed microcirculation. Ioxaglate, Iopromide, Iohexol and Iotrolan influence microcirculation differently but always to a far less degree.

Animals↗
PubMed1989

[Experimental studies of the vascular reactions in selected microcirculatory areas as affected by various x-ray contrast media].

After application of various ionic and non-ionic contrast media in the myocardium and intestine of rats, significant changes of flow conditions in the terminal vascular bed were observed with intravital microscopy: Amidotrizoate causes severe disorder in microcirculation distribution (heterogeneous perfusion, functional shunts), while Ioxaglate, Iopromide, Iohexol, Iotrolan cause significantly less microcirculation reactions.

Animals↗
PubMed1987

[Improvement in the prognosis of renal cell carcinoma by percutaneous transvascular embolization].

In a retrospective study of 303 patients with renal cell carcinomas the prognostic influence of the percutaneous transvasal embolization of the renal artery was demonstrated. In form of the life-table-method we compared statistically the survival rates of preoperatively or palliatively embolized patients with such ones who were only nephrectomized or treated only symptomatically. In the tumour stages T2 and T3 the preoperative percutaneous transvasal embolization leads to a clearly higher survival rate; in stage T2 statistically significant. After palliative embolization the improvement of the prognosis is evident compared with the inoperable patients who were treated only symptomatically. The prognosis after palliative preoperative percutaneous transvasal embolization and retarded nephrectomy is not worse than after preoperative percutaneous transvasal embolization and immediate nephrectomy. The effect of the preoperative and palliative embolization improving the prognosis should incite all partners who up to now objected to this therapeutic method to reconsider their therapy concept.

Carcinoma, Renal Cell↗
PubMed1985

[Left ventricular function following transluminal coronary dilatation or operative revascularization in chronic ischemic heart disease].

To assess changes in resting left ventricular function after reestablishment of myocardial perfusion, echocardiographic studies were performed before, at three resp. six days after as well as three months after successful PTCA in 19 patients and after coronary artery bypass grafting in 20 patients. Reference data were obtained from analog processing of values from 20 healthy control subjects. Baseline values (in addition to primary morphologic criteria) were indicative of a clearly functional selection pattern. As compared with those undergoing PTCA, patients who underwent bypass surgery had more unfavorable values for ejection fraction at rest. Immediately after the intervention, there was a consistent tendency to transiently reduced resting pump function. At three months, however, in both groups, cardiac performance had returned to control values and the global and regional parameters of contractility had either reached or exceeded the preoperative values. The mean values showed more improvement in the PTCA group, a finding most probably attributable to the more favorable baseline situation. Paradoxic septum motion was found frequently in those who had undergone bypass surgery. All patients with grafting to the right coronary artery were included in the latter group. Whether perioperative injury, the varying perfusion conditions or the pericardiotomy is responsible for this phenomenon, remains to be established.

Adult↗