Search PubMed⌕ Search

Biomedical subjects

W Münster

Publications and source records attributed to W Münster.

At least 19 recordsLinked to original sources
PubMed1999

Influence of Iodixanol-270 and Iopentol-150 on the microcirculation in man: influence of viscosity on capillary perfusion.

UNLABELLED: PURPOSE, MATERIAL AND METHODS: The aim of this study was to investigate the influence of direct intraarterial application of the contrast agents Iodixanol-270 and Iopentol-150 on the capillary perfusion. This was accomplished through continuous recording of the capillary perfusion in the nailfold capillaries of the right hand before and after a bolus injection of 20 ml of contrast agent into the right axillary artery. RESULTS: After injecting 20 ml of Iodixanol-270, which has a high viscosity compared to the plasma viscosity, a statistically significant decrease in the erythrocyte velocity of 60.8% from 0.439+/-0.273 mm/s to 0.172+/-0.090 mm/s was observed already 10 s after the injection (p = 0.0001). The decreased velocity was maintained until the end of the observation period of 6 min. In contrast to this finding, no change in the erythrocyte velocity was observed after injection of 20 ml of the low-viscous Iopentol-150 (p = 0.1508). CONCLUSIONS: The erythrocyte velocity in cutaneous capillaries therefore strongly depends on the viscosity of the contrast agent.

Aged↗
PubMed1998

Polyamine modulation of mitochondrial calcium transport. I. Stimulatory and inhibitory effects of aliphatic polyamines, aminoglucosides and other polyamine analogues on mitochondrial calcium uptake.

In this study, the regulation of mitochondrial Ca2+ transport by polyamines structurally related to spermine and by analogous polycationic compounds was characterized. Similar to spermine, a number of amino groups containing cationic compounds exerted a dual effect on Ca2+ transport of isolated rat liver mitochondria: a decrease in Ca2+ uptake velocity and an enhancement of Ca2+ accumulation. In contrast to the effects of spermine and other aliphatic polyamines, however, the accumulation-enhancing effect of aminoglucosides, basic polypeptides, and metal-amine complexes turned into an inhibition of Ca2+ accumulation at higher concentrations. Within groups of structurally related compounds, the potency to decrease Ca2+ uptake velocity and to enhance Ca2+ accumulation correlated with the number of cationic charges. The presence of multiple, distributed cationic charges was a necessary, but not sufficient criterion for effects on mitochondrial Ca2+ transport, because cationic polyamines and basic oligopeptides which did not enhance mitochondrial Ca2+ accumulation could be identified. Spermine was not able to antagonize the blocking of Ca2+ uptake by ruthenium red, but rather showed an apparent synergism, which can be explained as a displacement of membrane-bound Ca2+ by spermine. The aminoglucosides, gentamicin and neomycin, but not the inactive polyamine bis(hexamethylene)-triamine, inhibited the binding of spermine to intact mitochondria. Apparently, the binding of spermine, gentamicin, and a number of polyamine analogues to low-affinity binding sites at mitochondria, which have low, but distinct structural requirements and which may correspond to phospholipid headgroups, indirectly influences the activity state of the mitochondrial Ca2+ uniporter. The ability of aminoglucosides to displace spermine from the mitochondria and to inhibit mitochondrial Ca2+ accumulation may contribute to the mitochondrial lesions, which are known to occur early in the course of aminoglucoside-induced nephrotoxicity.

Aminoglycosides↗
PubMed1996

Relation between accumulation of phospholipase A2 reaction products and Ca2+ release in isolated liver mitochondria.

A Ca(2+)-dependent stimulation of mitochondrial phospholipase A2 is often assumed to play a role in mitochondrial Ca2+ release. We sought to clarify this relation by measuring Ca2+ transport and determining phospholipase A2 reaction products from the same sample of isolated, incubated rat liver mitochondria. When mitochondria had accumulated and spontaneously released again Ca2+, most probably by membrane permeability transition, there was no increase of phospholipase A2 reaction products. However, when the incubation was continued after Ca2+ release, significant increases of the content of lysophosphatidylcholine and unesterified fatty acids could be seen. Quinacrine, an inhibitor of phospholipase A2 activity, prevented Ca2+ release and p-hydroxymercuribenzoic acid, an inhibitor of lysophospholipid reesterification, induced a fast release of Ca2+ from isolated mitochondria. Such effects are usually taken as indirect evidence for a participation of phospholipase A2 in mitochondrial Ca2+ release, but analysis of the mitochondrial lipids revealed that no significant changes of the mass of phospholipase A2 reaction products had occurred. These experiments suggest that the accumulation of phospholipase A2 reaction products in mitochondria is the consequence rather than the cause of the membrane permeability transition. Exogenous phospholipase A2 products, lysophosphatidylcholine and arachidonic acid, induced mitochondrial Ca2+ release after a time lag, which decreased with aging of the mitochondrial preparation. The amount of lysophosphatidylcholine taken up by the mitochondria from the incubation medium during these experiments was measured and compared to the amount of lysophosphatidylcholine produced endogenously by mitochondrial phospholipase A2. From these data it appears likely that the amount of lysophosphatidylcholine generated in the mitochondria after the permeability transition is sufficient to sustain the permeable state. An accumulation of mitochondrially generated phospholipase A2 reaction products after the permeability transition could thus be a decisive factor for the limited reversibility of the membrane permeability transition.

Animals↗
PubMed1994

[100 years after Billroth... Laparoscopic Billroth I and Billroth II distal stomach resection].

In the period October 1993-February 1994, we performed three distal stomach resection operations laparoscopically (two Billroth-II anastomoses, one Billroth-I anastomosis combined with truncal vagotomy). The first patient, 83-year old, presented a stenosing, bleeding, prepyloric, malignant Non-Hodgkin lymphoma. The second patient, 84-year old, presented an ulcerated, non-malignant leiomyoblastoma of the antrum. Due to the histological type of the tumors a radical lymphadenectomy was not performed. The partially resected stomach (two thirds) was removed in a lap sac through a 3.5 cm infraumbilical incision. The third patient presented a persisting, prepyloric ulcer combined with an almost complete stenosis of the pylorus. In all three cases, it was possible to follow the principles of conventional open surgery. The anastomoses were all stapled intracorporally, no intraabdominal complications occurred. However, the first patient died on the 21st postoperative day from cardiopulmonary failure, the remaining two patients were discharged on day 11/day 12 postoperatively.

Aged↗
PubMed1993

Effect of spermine on mitochondrial matrix calcium in relation to its enhancement of mitochondrial calcium uptake.

The mechanism of spermine-induced enhancement of mitochondrial Ca2+ uptake was explored using the fluorescent Ca2+ indicator Fluo-3/AM to measure the free matrix Ca2+ concentration. Simultaneously, the extramitochondrial Ca2+ concentration was registered by a Ca(2+)-ion selective electrode. Spermine lowered the extramitochondrial steady state Ca2+ concentration and at the same time induced a decrease of the intramitochondrial Ca2+ concentration. However, there is a concentration-dependent reversal of the stimulatory action of spermine, which may be explained by the existence of a second, low-affinity binding site for spermine which mediates an inhibition of uptake in spite of the existence of an inwardly directed Ca2+ gradient.

Aniline Compounds↗
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↗