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M Rössle

Publications and source records attributed to M Rössle.

At least 19 recordsLinked to original sources
PubMed2006

Mechanical manipulation of molecular lattice parameters in smectic elastomers.

Smectic liquid crystalline elastomers (SLCE) represent unique materials that combine a 1-D molecular lattice arrangement and orientational order with rubber-elasticity mediated by a polymer network. Such materials may exhibit large thermo-mechanical, opto-mechanical and electro-mechanical effects, due to the coupling of macroscopic sample geometry and microscopic structural features. It is shown that the molecular layer dimensions in the smectic phases can be influenced reversibly by macroscopic strain of the material. We present a microscopic model on the basis of experimental results obtained by mechanical dilatation measurements, optical interferometry, X-ray scattering, (13)C NMR, FTIR and polarizing microscopy data. The model gives an explanation of the controversial results obtained in different types of smectic elastomers.

Computer Simulation↗
PubMed2006

Effect of vardenafil, an inhibitor of phosphodiesterase-5, on portal haemodynamics in normal and cirrhotic liver -- results of a pilot study.

BACKGROUND: Dysregulation of the cyclic guanosine 3',5' monophosphate-nitric oxide system is in part responsible for portal hypertension in cirrhosis. AIM: To test the effects of inhibitors of phosphodiesterase-5 on portal haemodynamics. METHODS: To 18 healthy subjects and 18 patients with Child A liver cirrhosis, 10 mg of vardenafil, an inhibitor of phosphodiesterase-5, were administered orally. Doppler sonographic measurements of hepatic and splanchnic blood flow, systemic blood pressure and heart rate were recorded before, 1 h after, and 48 h after the application. Vardenafil plasma levels were determined after 1 h. In five patients, invasive registration of free and wedged hepatic vein pressure was performed. RESULTS: Portal venous flow increased in patients from 0.82 +/- 0.30 L/min (mean +/- s.d.) by 26% (CI: 16-37%, P = 0.0004) and in healthy subjects from 0.75 +/- 0.20 L/min (mean +/- s.d.) by 19% (CI: 9-28%; P = 0.0010). Celiac and hepatic artery resistivity indices rose significantly. Systemic blood pressure decreased slightly in patients. The wedged hepatic venous pressure gradient decreased in four of five patients with liver cirrhosis. Vardenafil plasma levels were higher in patients (14 +/- 10 microg/L) than in healthy subjects (9 +/- 6 microg/L; n.s.). CONCLUSIONS: Inhibition of phosphodiesterase-5 increases portal flow and lowers portal pressure by a decrease in sinusoidal resistance and may be a novel therapeutic strategy for portal hypertension.

Adult↗
PubMed2006

The use of a polytetrafluoroethylene-covered stent graft for transjugular intrahepatic portosystemic shunt (TIPS): Long-term follow-up of 100 patients.

PURPOSE: To retrospectively evaluate results and clinical outcome of transjugular intrahepatic portosystemic shunt (TIPS) after implantation of a polytetrafluoroethylene (PTFE)-covered stent graft. MATERIAL AND METHODS: The stent graft was used in 112 patients with higher risk of primary (i.e. patients with Budd-Chiari syndrome) or secondary shunt failure (patients with occlusion of a previous uncovered stent), or a complicated TIPS procedure with an imminent technical complication requiring covered stent. Patients were scheduled at 3- to 6-month intervals for duplex-sonographic control of shunt function. Radiological revision was performed in patients with a decrease in shunt function by >25%, primary non-response, or relapse of the index symptom. RESULTS: Twelve patients were lost to follow-up, and 100 patients were followed for 22+/-15 months. The actuarial rates of shunt patency were 90, 84, and 74% at 1, 2, and 3 years of follow-up, respectively. Two patients developed early (within 1 month) and 14 patients late shunt failure. Except for one transient rise in liver enzymes due to outflow obstruction by the stent graft, no technical complications were seen. Primary response to treatment was seen in 97% of patients treated for variceal bleeding and 84% of patients treated for refractory ascites. A relapse of the index symptom was seen in 13% of bleeders and 9% of patients treated for refractory ascites. CONCLUSION: TIPS created with a PTFE-covered stent graft showed favorable long-term results.

Adolescent↗
PubMed2005

[A rare cause of subacute parotitis. The pathogenetic role of crystals from an infarcted Whartin's tumour?].

The etiology of a subacute inflammatory swelling in the area of the right parotid gland in a 62-years old man could not be resolved clinically. The histomorphological examination of the surgical specimen showed an intraglandular area of predominantly chronic histiocytic inflammation with foreign body reaction in the intimate neighbourhood of a small, subtotally infarcted Warthin's tumour. Not birefringent spindle-shaped crystals could be demonstrated both within the parotitis or intraluminally in vital parts of the Warthin's tumour. In terms of the possible causes of the severe intraglandular inflammation, all arguments favour a primary infarction of the Warthin's tumour with the release of intraluminal preformed crystals which secondarily induce a massive inflammation with foreign body reaction, corresponding to the clinical presentation of a subacute parotitis.

Acute Disease↗
PubMed2004

[Chronic circumferential aortic dissection with intimo-intimal intussusception].

A circumferential aortic dissection with so-called intimo-intimal intussusception is a very rare complication of a dissecting aneurysm, in which the sock-like intimal flap is upended in the true lumen by the blood stream. The few cases reported thus far are based on radiological or intraoperative findings in acute dissections. The present postmortem study documents the very rare case of long-term survival of a chronic circumferential dissection with intimo-intimal intussusception.

Aortic Dissection↗
PubMed2001

Severe veno-occlusive disease after allogeneic bone marrow or peripheral stem cell transplantation--role of transjugular intrahepatic portosystemic shunt (TIPS).

AIMS: Veno-occlusive disease of the liver is a severe complication of allogeneic bone marrow or peripheral stem cell transplantation with a high mortality. In its severe form, the portal vein is used as an outflow tract for the arterial hepatic perfusion. A portosystemic side-to-side shunt, e.g. a transjugular intrahepatic portosystemic shunt, may facilitate portal outflow thus increasing hepatic (i.e. arterial) perfusion. METHODS: The effect of a transjugular shunt on liver function and blood flow was studied in three patients receiving shunt treatment 0-2 days after the diagnosis of severe veno-occlusive disease occurring 28, 20, and 17 days after allogeneic transplantation for acute myeloid leukemia, Hodgkin's disease and chronic myeloid leukemia, respectively. RESULTS: The transjugular shunt reduced the portosystemic pressure gradient from 23 to 8, 18 to 5, and 33 to 13 mmHg in patients 1, 2, and 3, respectively, increased the stagnant portal vein flow to normal, and decreased the arterial resistive index, indicating an increase in the arterial perfusion of the liver. This was accompanied by rapid relief from abdominal pain and removal of ascites. The AST concentration dropped from 1230, 417, and 2930 U/l before to 93, 20, and 41 U/l and the PT-time ratio improved 3-7 days after shunt treatment while the bilirubin concentration continued to rise until the patients died 26, 42, and 33 days after transplantation from multiorgan failure (two patients) or intracerebral hemorrhage. CONCLUSIONS: The transjugular shunt may have improved abdominal and hepatic perfusion and prevented further necrosis of hepatocytes. It did not, however, affect jaundice or survival, which was limited by extrahepatic complications.

Adult↗
PubMed2001

Quantification of mucosal leucocyte endothelial cell interaction by in vivo fluorescence microscopy in experimental colitis in mice.

Leucocyte recruitment to sites of intestinal inflammation is a crucial, multi-step process that leads ultimately to the accumulation of cells in the inflamed tissue. We established a new in vivo model system of experimental colitis to quantify leucocyte-endothelial cell interaction and leucocyte extravasation in the inflamed mucosa of the colon. Furthermore, we investigated the pathophysiological role of ICAM-1 in the intestinal microcirculation in vivo. Using the model of dextran sodium sulphate (DSS)-induced acute and chronic colitis in mice, in vivo microscopy was performed in the colonic submucosal postcapillary venules and the submucosal collecting venules in normal or inflamed murine colonic segments. ICAM-1 expression was blocked by an anti-ICAM-1 monoclonal antibody or by suppressing NF-kappaB activation by gliotoxin. Significant increases in leucocyte adhesiveness (51-fold in postcapillary venules, 30-fold in collecting venules, P < 0.01) and extravasation (6.5-fold) could be demonstrated as early as day 2 of DSS-application in acute colitis (P < 0.01). This was paralleled by increases in both the histological damage scores and myeloperoxidase activities. In chronic dextran sodium sulphate-induced colitis significant increases in leucocyte-endothelium interactions and leucocyte extravasation were observed. Blocking ICAM-1 expression with a monoclonal antibody or gliotoxin, leucocyte sticking and extravasation were significantly down-regulated in vivo compared to controls (> 70%; P < 0.01). This new model system offers the possibility to specifically assess the role of adhesion molecules in the colonic mucosa in vivo as well as to investigate and quantify the effectiveness of experimental therapeutic approaches in acute or chronic intestinal inflammation.

Acute Disease↗
PubMed2001

Prevention of rebleeding from oesophageal-gastric varices.

Endoscopic sclerotherapy or ligation and/or drugs are the standard treatments for the prevention of variceal rebleeding. Failure of this treatment indicates the need for rescue transjugular intrahepatic portosystemic shunt (TIPS) implantation. The current practice to use endoscopic treatment as first-line and TIPS as second-line treatment is, however, not based on evidence since, in unselected patients, both treatments have a comparable survival. In addition, the timing for a change from endoscopic treatment to TIPS is not exactly defined. According to the randomized studies available a change may be recommended when uncontrolled rebleeding or more than two rebleedings within a time interval of 6-12 months indicate failure of the endoscopic treatment. This regimen may be reconsidered when future developments improve outcome of one or the other treatment. In this regard the TIPS treatment has a potential of improvement if further reduction of the rate of rebleeding can be achieved with less stenosis, and/or reduced encephalopathy.

Endoscopy↗
PubMed2001

Treatment of refractory hepatic hydrothorax with transjugular intrahepatic portosystemic shunt: long-term results in 40 patients.

BACKGROUND/AIMS: Hepatic hydrothorax is a complication of portal hypertension secondary to ascites. In this study, we investigated retrospectively the effects of the transjugular intrahepatic portosystemic shunt (TIPS) on hepatic hydrothorax refractory to diuretic treatment. METHODS: Forty patients (Child-Pugh class B, 24 patients; Child-Pugh class C, 16 patients) with hydrothorax refractory to diuretic treatment, pleurocenteses or pleurodesis were included. The TIPS implantation was successful in all patients, who were then followed for 16 +/- 14 months (range 1 day-54 months). RESULTS: TIPS reduced the portosystemic pressure gradient from 26 +/- 6 to 10 +/- 5 mmHg. In the 17 patients whom we followed for 12 months or longer, improvements were found for the Child--Pugh score (8.6 +/- 1.8 v. 6.7 +/- 1.5), serum albumin concentration (3.1 +/- 0.5 v. 3.6 +/- 0.5 g/l), and urinary sodium excretion (22 +/- 29 v. 89 +/- 43 mmol/24 h) (P< 0.05). Two patients developed severe hepatic encephalopathy requiring shunt occlusion. Hydrothorax improved in 82% of patients and resolved in 71% of patients. Fifty per cent of patients developed shunt insufficiency within 7 +/- 9 months, contributing to a probability of relapse-free 1-year survival of 35%. In these patients, shunt revision resulted in a secondary response rate of 82.3%. The 1-year survival was 64%. Both hydrothorax response and survival showed a significant inverse correlation with age over 60 years (P< 0.01 and P< 0.003, respectively) but not with other biomedical variables. CONCLUSION: TIPS is effective for hydrothorax refractory to diuretic treatment and other standard interventions to bridge the time to transplantation. Patients older than 60 years have a poor response and short survival.

Adult↗
PubMed2001

How much reduction in portal pressure is necessary to prevent variceal rebleeding? A longitudinal study in 225 patients with transjugular intrahepatic portosystemic shunts.

OBJECTIVES: This longitudinal study determines the risk of rebleeding in relation to the reduction of the portosystemic pressure gradient in patients with a transjugular intrahepatic portosystemic shunt (TIPS) for variceal bleeding. METHODS: The study included 225 patients in whom a TIPS revision was indicated by the endoscopic finding of varices with a high risk for rebleeding (n = 167) or a recent variceal rebleed (n = 58). The portosystemic pressure gradient was determined before and after TIPS placement and at revision performed after a mean of 10 +/- 15 months. RESULTS: The portosystemic pressure gradient at revision approached the index pressure gradient before TIPS implantation (23.1 +/- 5.5 mm Hg) by 8.4 +/- 31%. Rebleeding was inversely correlated with the reduction in index pressure gradient found at revision. Thus, 80% of rebleedings occurred with pressure gradients close to the index pressure gradient (< 25% reduction) or with gradients equal to or greater than the index pressure gradient. In contrast, only one patient (0.4%) and three patients (1.3%) rebled with a pressure gradient of < 12 mm Hg or a reduction of the index pressure gradient by > 50%, respectively. Kaplan-Meier analysis of rebleeding, which included the 225 patients at risk, showed a probability of rebleeding of 18%, 7%, and 1% for a reduction of the index pressure gradient by 0%, 25-50%, and > 50%, respectively. CONCLUSIONS: Most rebleedings occurred with pressure gradients similar to the index-pressure gradient measured at first bleeding. Accordingly, a graded reduction by 25-50% sufficiently prevents rebleeding. It can be assumed that, in comparison with the widely used threshold value of 12 mm Hg, a reduction by 25-50% may have a favorable benefit-to-risk ratio with respect to shunt-induced hepatic encephalopathy and liver failure. It should therefore be a goal in the decompressive treatment of portal hypertension and maintained during follow-up of patients with variceal bleeding.

Adult↗
PubMed2000

A comparison of paracentesis and transjugular intrahepatic portosystemic shunting in patients with ascites.

BACKGROUND: In patients with cirrhosis and ascites, creation of a transjugular intrahepatic portosystemic shunt may reduce the ascites and improve renal function. However, the benefit of this procedure as compared with that of large-volume paracentesis is uncertain. METHODS: We randomly assigned 60 patients with cirrhosis and refractory or recurrent ascites (Child-Pugh class B in 42 patients and class C in 18 patients) to treatment with a transjugular shunt (29 patients) or large-volume paracentesis (31 patients). The mean (+/-SD) duration of follow-up was 45+/-16 months among those assigned to shunting and 44+/-18 months among those assigned to paracentesis. The primary outcome was survival without liver transplantation. RESULTS: Among the patients in the shunt group, 15 died and 1 underwent liver transplantation during the study period, as compared with 23 patients and 2 patients, respectively, in the paracentesis group. The probability of survival without liver transplantation was 69 percent at one year and 58 percent at two years in the shunt group, as compared with 52 percent and 32 percent in the paracentesis group (P=0.11 for the overall comparison, by the log-rank test). In a multivariate analysis, treatment with transjugular shunting was independently associated with survival without the need for transplantation (P=0.02). At three months, 61 percent of the patients in the shunt group and 18 percent of those in the paracentesis group had no ascites (P=0.006). The frequency of hepatic encephalopathy was similar in the two groups. Of the patients assigned to paracentesis in whom this procedure was unsuccessful, 10 received a transjugular shunt a mean of 5.5+/-4 months after randomization; 4 had a response to this rescue treatment. CONCLUSIONS: In comparison with large-volume paracentesis, the creation of a transjugular intrahepatic portosystemic shunt can improve the chance of survival without liver transplantation in patients with refractory or recurrent ascites.

Adult↗
PubMed2000

Conformational rearrangements of an archaeal chaperonin upon ATPase cycling.

Chaperonins are double-ring protein assemblies with a central cavity that provides a sequestered environment for in vivo protein folding. Their reaction cycle is thought to consist of a nucleotide-regulated alternation between an open substrate-acceptor state and a closed folding-active state. The cavity of ATP-charged group I chaperonins, typified by Escherichia coli GroEL [1], is sealed off by a co-chaperonin, whereas group II chaperonins--the archaeal thermosome and eukaryotic TRiC/CCT [2]--possess a built-in lid [3-5]. The mechanism of the lid's rearrangements requires clarification, as even in the absence of nucleotides, thermosomes of Thermoplama acidophilum appear open in vitrified ice [6] and closed in crystals [4]. Here we analyze the conformation of the thermosome at each step of the ATPase cycle by small-angle neutron scattering. The apo-chaperonin is open in solution, and ATP binding induces its further expansion. Closure seems to occur during ATP hydrolysis and before phosphate release, and represents the rate-limiting step of the cycle. The same closure can be triggered by the crystallization buffer. Thus, the allosteric regulation of group II chaperonins appears different from that of their group I counterparts.

Adenosine Triphosphatases↗
PubMed2000

Complementary visualization of mitotic barley chromatin by field-emission scanning electron microscopy and scanning force microscopy.

The surface structure of mitotic barley chromatin was studied by field-emission scanning electron microscopy (FESEM) and scanning force microscopy (SFM). Different stages of the cell cycle were accessible after a cell suspension was dropped onto a glass surface, chemical fixed, and critically point dried. Imaging was carried out with metal-coated specimen or uncoated specimen (only for SFM). The spatial contour of the chromatin could be resolved by SFM correlating to FESEM data. The experimentally determined volume of the residue chromatin during mitosis was within the range of 65-85 microm(3). A comparison with the theoretically calculated volume indicated a contribution of about 40% of internal cavities. Decondensation of chromosomes by proteinase K led to a drastic decrease in the chromosome volume, and a 3-D netlike architecture of the residue nucleoprotein material, similar to that in the intact chromosome, was obvious. Incubation of metaphase chromosomes in citrate buffer permitted access to different levels of chromatin packing. We imaged intact chromosomes in liquid by SFM without any intermediate drying step. A granular surface was obvious but with an appreciably lower resolution. Under similar imaging conditions proteinase K-treated chromosomes exhibited low topographic contrast but were susceptible to plastic deformations.

Chromatin↗
PubMed1999

Platelet aggregation and platelet-derived growth factor inhibition for prevention of insufficiency of the transjugular intrahepatic portosystemic shunt: a randomized study comparing trapidil plus ticlopidine with heparin treatment.

Intimal proliferation at the interface between prosthetic material and tissue is an intrinsic phenomenon of stenting and the major cause of insufficiency of the transjugular intrahepatic portosystemic shunt (TIPS). For its prevention, a randomized study was performed comparing standard heparin treatment with a combination of trapidil, a drug with anti-platelet-derived growth factor (PDGF) activity, and ticlopidine, a platelet aggregation inhibitor. Ninety patients with cirrhosis who received a transjugular shunt were randomized, and 84 patients completed the trial. Group 1 (n = 42) received a bolus of heparin (12 to 24 U/kg) at shunt placement, followed by 1 week of intravenous and 4 weeks of subcutaneous heparin treatment. Group 2 (n = 42) received the same heparin bolus, followed by a 1-day intravenous heparin treatment and a 6-month treatment with trapidil (400 mg/d) and ticlopidine (250 mg/d). Shunt function was assessed by duplex-sonography and angiography. Stenoses were classified according to their location as type 1 (within the stent) and type 2 (in the draining hepatic vein). The estimated rate of overall stenoses (intention-to-treat analysis) at 1 year showed a significant reduction in patients receiving trapidil and ticlopidine (group 2) as compared with heparin (33 vs. 57%; P =.047). There was no difference in the estimated 1-year rate of type 1 stenoses between the two groups, but there was a significant reduction in type 2 stenoses (group 1: 58%, group 2: 19%; P =.016). The treatment effect continued after withdrawal of the drugs and was accompanied by a decreased incidence of rebleeding. The study demonstrates that the incidence of type 2 stenosis of the transjugular shunt can be reduced by combined inhibition of platelet aggregation and PDGF activity. The findings may be of relevance not only for the transjugular shunt, but also for other stent applications, e.g., vascular and biliary, as well as for bypass and shunt surgery.

Drug Therapy, Combination↗
PubMed1999

Cardiac function and haemodynamics in alcoholic cirrhosis and effects of the transjugular intrahepatic portosystemic stent shunt.

BACKGROUND: A portosystemic stent shunt may impair cardiac function and haemodynamics. AIMS: To investigate the effects of a transjugular intrahepatic portosystemic shunt (TIPS) on cardiac function and pulmonary and systemic circulation in patients with alcoholic cirrhosis. PATIENTS/METHODS: 17 patients with alcoholic cirrhosis and recent variceal bleeding were evaluated by echocardiography and catheterisation of the splanchnic and pulmonary circulation before and after TIPS. The period of catheter measurement was extended to nine hours in nine of the patients. The portal vein was investigated by Doppler ultrasound before and nine hours after TIPS. RESULTS: Baseline echocardiography showed the left atrial diameter to be slightly increased and the left ventricular volume to be in the upper normal range. Nine hours after TIPS, the left atrial diameter and left ventricular end diastolic volume were increased (by 6% (p<0.01) and 7% (p<0.01) respectively); end systolic volume had not changed significantly. Invasive measurements showed a sharp increase in right atrial pressure (by 101%; p<0.01), mean pulmonary artery pressure (by 92%; p<0.01), pulmonary capillary wedge pressure (by 111%; p<0.01), and cardiac output (8.1 (1.6) to 11.9 (2.4) l/min; p<0.01). Systemic vascular resistance decreased (824 (242) to 600 (265) dyn.s.cm-5 p<0.01), and total pulmonary resistance increased (140 (58.5) to 188 (69.5) dyn.s.cm-5; p<0.05). Total pulmonary resistance (12%; NS), cardiac output (1.4 l/min; p<0. 05), and portal vein blood flow (1.4 l/min; p<0.05) remained elevated for nine hours after TIPS in the subgroup. Portoatrial pressure gradient (43%; p<0.05), portohepatic vascular resistance (72%; p<0.05), and systemic vascular resistance (27%; p<0.01) were consistently reduced. CONCLUSIONS: The increase in the left atrial diameter, the pulmonary capillary wedge pressure, and total pulmonary resistance observed after the TIPS procedure reflected diastolic dysfunction of the hyperdynamic left ventricle in patients with alcoholic cirrhosis. The haemodynamic effects of the portosystemic stent shunt itself on the splanchnic circulation seem to be mainly responsible for the further decrease in systemic vascular resistance. TIPS may unmask a coexisting preclinical cardiomyopathy in patients with alcoholic cirrhosis and portal hypertension.

Adult↗