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Biomedical subjects

M Walter

Publications and source records attributed to M Walter.

At least 127 records · Page 7Linked to original sources
PubMed1996

Gasless videoendoscopic implantation of an aortobifemoral vascular prosthesis via a transperitoneal versus extraperitoneal approach: an experimental study.

PURPOSE: To report progress in the development of a new minimally invasive surgical technique for aortobifemoral grafting utilizing gasless videoendoscopy. METHODS: In an experimental study, aortobifemoral Dacron vascular prostheses were implanted in 20 human cadavers using videoendoscopic techniques in both transperitoneal and extraperitoneal approaches. Rather than inducing pneumoperitoneum, the abdominal wall was elevated with an electrically powered lifting system. RESULTS: Each approach was utilized in 10 cadavers for implantation of 20 aortobifemoral grafts under endoscopic guidance in a gasless field. Average operative time for transperitoneal approach was 3.8 hours (range 3.0 to 5.5), slightly less than the average 4.1 hours (range 3.0 to 6.0) for the extraperitoneal access. Both access routes provided adequate visualization of the operative field. CONCLUSIONS: Advantages of gasless endoscopy include the use of conventional instruments and the potential benefits associated with a minimally invasive approach. Optical magnification facilitates suturing of the femoral anastomosis, improves examination of the vascular walls, and allows a more accurate suturing technique.

Aorta, Abdominal↗
PubMed1996

[Current treatment strategy in malignant pleural effusion].

Malignant pleural effusions are a grave consequence of advanced cancer disease. The successful suppression of pleural fluid reaccumulation can make a major contribution to the management and palliative care of patients with disseminated cancer. Many treatment concepts have been reported in the literature. The recommended therapy in malignant pleural effusions consists of intrapleural instillation of a sclerotic agent to produce pleurodesis. Different substances have been used, including tetracyclines, cytostatic agents, fibrin, talc, Corynebacterium parvum, cytokines and others. We reviewed the most frequently used techniques of pleurodesis in order to define the most effective treatment concept. In 15 prospective randomized trials the success rates varied from 13% with bleomycin to 100% with talc or Corynebacterium parvum. Talc was superior to other agents in 6 of 6, Corynebacterium parvum in 3 of 4 and bleomycin or tetracycline only in 3 of 8 studies. Adverse effects were frequently observed with cytostatic agents, but were very rare in the case of talc or fibrin instillation. Comparing the recently published data pleurodesis with talc appears to be the most effective treatment strategy, followed by Corynebacterium parvum, bleomycin and tetracycline.

Antibiotics, Antineoplastic↗
PubMed1996

Validity of SEP monitoring in carotid surgery. Review and own results.

OBJECTIVE: The sensitivity of intraoperative monitoring by means of somatosensory evoked potentials (SEP) in carotid surgery is to be examined. EXPERIMENTAL DESIGN: Prospective clinical investigation. In addition, the influence of circulatory parameters on SEP curves will also be tested. SETTING: Department of Surgery of a university clinic. MATERIALS AND METHODS: A total of 200 patients underwent intraoperative monitoring by means of somatosensory evoked potentials (SEP) during carotid endarterectomy between March 1, 1991 and August 1, 1994. MEASURES: In order to exclude blood pressure variations as a cause for amplitude changes the blood pressure and pulse were documented during the entire phase of preparation and clamping. RESULTS: A significant correlation could not be established between parameters of circulation and amplitude changes (r = 0.0026; p = 0.62). In seven cases of intraoperative amplitude reduction of more than 50% a stroke has been avoided by inserting a shunt. Despite the lack of an amplitude reduction, a watershed stroke of A.cerebri media and A.cerebri posterior occurred in two instances. Taking this into consideration the sensitivity of monitoring is 99.0% at a specificity of 100%. CONCLUSIONS: SEP-monitoring in carotid endarterectomy is simple to execute and is superior in sensitivity to EEG analysis. To avoid artefaction by anesthesia, a standard injection anesthesia is recommended. Farfield potentials should also be derived to avoid watershed infarctions.

Blood Pressure↗
PubMed1996

High density lipoproteins enhance the Na+/H+ antiport in human platelets.

In the present study, we investigated the effect of high density lipoproteins 3 (HDL3) on Na+/H+ exchanger activity and cytosolic pH (pHi) in human platelets. HDL3 alone failed to affect pHi, but preincubation with HDL3 significantly enhanced the Na+/H+ antiport activation brought about by acidification with 100 mM sodium propionate or stimulation with 0.05 U/ml thrombin. the stimulatory effect of HDL3 was unaffected by indomethacin excluding a role for cyclooxygenase products. The HDL3 effect was not mediated by Ca2+/calmodulin-dependent protein kinase as HDL3 failed to increase cytosolic free calcium concentration. However, the potentiating effect of HDL3 was completely blocked in the presence of the protein kinase C inhibitor, bisindoylmaleimide and the phosphatidylcholine-specific phospholipase C inhibitor, D609. Furthermore, the effect of HDL3 was abolished after covalent modification of HDL3 with dimethylsuberimidate and was not observed in platelets from Glanzmann thrombasthenia type 1 which do not express GP IIb/IIIa, as well as in platelets preincubated with anti-GP IIb/IIIa polyclonal antibodies. We conclude that HDL3 enhances the sodium propionate- and thrombin-induced Na+/H+ antiport activity in human platelets via binding to GP IIb/IIIa and activation of protein kinase C and phosphatidylcholine-specific phospholipase C.

Blood Platelets↗
PubMed1996

[The beginnings of reconstructive vascular surgery in Austria].

Hans von Haberer (1875-1958) gained wide experience in the reconstructive surgery of traumatic aneurysms during the 1st world war at the Surgical Department of the University of Innsbruck. In the period 1914-1918 he operated on altogether 201 vascular aneurysms, mainly using a direct circular vascular suture. In 1914 von Haberer described the first reconstruction of a carotid aneurysm. On the basis of the detailed case notes and operation reports written by Hans von Haberer between 1904 und 1949 on approximately 16000 cases and from the contemporary literature, we describe his experiences in vascular surgery at the Surgical Department of the University of Innsbruck between 1914 and 1918.

Austria↗
PubMed1996

[Talc pleurodesis in recurrent malignant pleural effusion--a prospective follow-up study].

Talc pleurodesis was performed in a prospective trial in 38 patients with recurrent malignant pleural effusion. After insertion of a chest tube a slurry containing 8g of iodined talcum, 0.5 ml of 1% xylocain/kg/body weight, and 80 ml of 0.9% NaCl was administered and suction drainage was performed. The chest tube could be removed after 4 +/- 1.7 days. A successful therapy could be achieved in 33/38 patients (86.8%). 2 patients (5.3%) suffered from recurrent pleural effusion which only in 1 case had to be drained. 3 patients died within the first month after talc pleurodesis due to an advanced cancer stage. Complications did not come to evidence in any case.

Adult↗
PubMed1996

[Preliminary results of a prospective randomized study vascular replacement above the knee].

In case of insufficient or missing greater saphenal vein or if the saphenal vein might be of important use for future bypass grafts, the question arises which alternative bypass material is the more appropriate choice. A literature review to that topic produced only unsatisfactory results. In a prospective randomized controlled clinical study (n = 250 patients) we compare the patency rates of either PTFE or Dacron as bypass material for femoropopliteal P-I-Bypass in chronic arterial occlusive disease. A preliminary evaluation of n = 103 patients (PTFE n = 52; Dacron n = 51) reveals an operative and immediate mortality rate of 0% and a loss of limb rate of 3.9% (PTFE) and 3.8% (Dacron). The secondary cumulative patency rate after 540 days of observation is 79.6% (PTFE) and 87.1% (Dacron). We so far find no statistically significant difference between both graft materials.

Adult↗
PubMed1996

Effects of a hemoglobin-based oxygen carrier (HBOC-201) on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery.

We conducted a pilot study to evaluate the effects of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After induction of anesthesia and isovolemic hemodilution with 1 L of lactated Ringer's solution, 13 patients were randomly assigned to receive, within 30 min, 3 mL/kg of either HBOC-201 or 6% hydroxyethyl starch (HES). Monitored variables included invasive arterial and pulmonary artery pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic and pulmonary vascular resistance indices, oxygen delivery index (DO2I), oxygen consumption index (VO2I), and oxygen extraction ratio (O2ER). Thirty minutes after HBOC-201 infusion, mean arterial pressure, systemic vascular resistance index, and CI were 149% (P = 0.028), 169% (P = 0.046), and 75% (P = 0.46) of the preinfusion values, respectively. No significant changes were noticed in heart rate and pulmonary vascular resistance index. DO2I and VO2I, 30 min after the infusion of HBOC-201, were 79% (P = 0.046) and 76% (P = 0.028) of the preinfusion values, respectively, whereas CaO2 and O2ER remained unaffected. We conclude that HBOC-201, at a dose of 3 mL/kg, impairs oxygen delivery because of adverse effects on cardiac output.

Adolescent↗
PubMed1996

[Institutional handling of criminal measures in sexual abuse. Results of a survey of experts].

A broad spectrum of very different institutions is confronted with the problem of sexual child abuse. So far, only a few systematic descriptions of institutional interventions and their impact on sexually abused children exist. In this article, first results are presented of a study investigating "individual and institutional reactions on sexual child abuse'. In dealing with this problem legal provisions are of special importance. The results presented are based on data obtained from questionnaires and qualitative interviews with experts (median of vocation experience: 8 years) in two german cities (berlin/cologne). Questionnaires were filled in by 195 experts from the entire institutional spectrum (counselors, clinical centres, youth welfare departments, public prosecutors, courts of justice, police), of whom 40 additionally took part in a detailed interview. This article focuses on the question, how different institutions handle legal provisions. The use of criminal law exemplarily shows the different impact of legal provisions on the interventions of counselors. The close connection between the assessment of legal interventions and counseling concepts could be shown at the example of the allegedly homogeneous group of specific counselors.

Adolescent↗
PubMed1996

[Therapy of renovascular hypertension in neurofibromatosis: surgical revascularization versus percutaneous transluminal angioplasty].

Vasculopathy is a rare and undervalued complication in neurofibromatosis. Histopathological changes of the vascular wall may lead to relevant renal artery stenosis. We report a case of a 17-year-old patient with neurofibromatosis and severe renovascular hypertension resulting from a proximal renal artery stenosis. Attempted percutaneous renal angioplasty was unsuccessful and the patient was referred for operative revascularization. After insertion of an aortorenal bypass with a reversed saphenous vein graft the patient became normotensive without medication. Based on our own experience and a review of the literature we recommend operative reconstruction of stenotic renal arteries in neurofibromatosis.

Adolescent↗
PubMed1995

HDL3 activates phospholipase D in normal but not in glycoprotein IIb/IIIa-deficient platelets.

Glycoprotein IIb/IIIa has been proposed as the platelet receptor for high density lipoproteins (HDL3). We characterized the HDL3-induced second messenger response in normal and glycoprotein IIb/IIIa-deficient platelets. In normal platelets physiological concentrations of HDL3 induced the time-dependent generation of phosphatidic acid in the absence of phosphoinositide turnover. The rise in phosphatidic acid preceded that of diacyglycerol which was inconsistent with phospholipase C/diacylglycerol kinase pathway being the source of phosphatidic acid and suggested the involvement of phospholipase D. In the presence of butanol, HDL3 stimulated the accumulation of phosphatidylbutanol, an unequivocal indicator of phospholipase D activity. No increase in phosphatidic acid, diacylglycerol, and phosphatidylbutanol was observed upon addition of HDL3 to glycoprotein IIb/IIIa-deficient platelets. We conclude that phosphatidic acid is generated in HDL3-stimulated platelets by phospholipase D and that glycoprotein IIb/IIIa is the receptor involved in this process.

Diglycerides↗
PubMed1995

Identification of an inhibitory element within the human 68-kDa (U1) ribonucleoprotein antigen.

Various nuclear proteins are the major targets of autoimmune responses in various rheumatic disorders. In particular, autoantibodies directed against a 68-kDa protein associated with the (U1) RNA-containing small nuclear ribonucleoprotein complexes typically occur in sera of patients with mixed connective tissue disease and related rheumatic disorders, such as systemic lupus erythematosus, and therefore are very useful as a serological marker. For establishing powerful immunoassays, it was necessary to generate recombinant human P68 antigen as the antigenic target. In this study we demonstrated that the cDNA coding for the full-length human P68 antigen could not be expressed by a traditional bacterial vector system due to a putative inhibitory sequence designated as inhibitory sequence X which is located between the autoreactive domains C' and D' of the human P68 antigen. The construction of corresponding hybrid plasmids carrying two functional and independent gene blocks indicated the trans-active function of the inhibitory sequence X, which could be localized by expression studies of various deletion constructs. Comparable Northern blot analysis clearly demonstrated that the inhibitory sequence X could act on the translation of the P68 mRNA. After excision of the inhibitory sequence X a dramatic increase in the production of recombinant human P68 antigen was observed.

Amino Acid Sequence↗
PubMed1995

Autoreactive epitopes within the human alpha-enolase and their recognition by sera from patients with endometriosis.

Patients with endometriosis significantly develop autoantibodies directed against endometrial proteins, which may be involved in the aetiology of this gynaecological disease. Based on standard Western blot analysis, a 48 kDa protein was localized in the soluble protein extract of endometrial adenocarcinoma cells using sera from patients with clinically staged endometriosis and identified as the glycolytic enzyme alpha-enolase. The corresponding cDNA coding for the human alpha-enolase was isolated from a human endometrial cDNA library and cloned into the vector pH6EX3, allowing the efficient expression of recombinant human alpha-enolase with an N-terminal histidine-hexapeptide as affinity ligand in Escherichia coli. The purified recombinant human alpha-enolase was evaluated as a specific antigenic tool for the diagnostic measurement of antiendometrial antibodies in sera from patients with endometriosis. With selected endometriosis sera, two linear autoreactive epitopes were localized within the recombinant human alpha-enolase using epitope mapping techniques, and they were characterized.

Adenocarcinoma↗
PubMed1995

The thrombosed popliteal aneurysm with distal arterial occlusion--successful therapy by interdisciplinary management.

Aneurysms of the popliteal artery are rare. Their rate of incidence is reported from 0.1% up to 2.8%. Whereas surgical treatment in an asymptomatic stage bears no problems, the symptomatic stage in a high percentage of patients leads to extremity loss due to thrombosis or embolism. In these cases, amputation rates are reported from 16 to 69%. In the period 1981 - 1994 we saw 39 patients suffering from 58 popliteal aneurysms: 53.4% of these aneurysms were symptomatic. 24.1% of the popliteal aneurysms angiographically showed an occlusion of the popliteal and peripheral outflow tract with concomitant critical limb ischemia. By applying a preoperative local catheter fibrinolysis the outflow tract could be reopened in 13 ischemic extremities and a receiving segment could be recanalized for reconstruction. Following this procedure, in spite of the high number symptomatic cases we gained very good postoperative results in 70.7% of the treated extremities after a maximum follow-up time of 62 months. An aneurysm is commonly seen as a contraindication for the application of lytic therapy. But in the presence of critical extremity ischemia due to a thrombosed or embolizing popliteal aneurysm, preoperative catheter fibrinolysis can often help to save the extremity.

Adult↗
PubMed1995

HDL3 stimulates multiple signaling pathways in human skin fibroblasts.

The influence of HDL3 on phospholipid breakdown was examined in human skin fibroblasts. HDL3 elicited phosphatidylcholine (PC) and phosphatidylinositol (PI) turnover and activated multiple phospholipases. In [14C]lyso-PC-labeled or [14C]choline (Cho)-labeled cells, a biphasic activation of PC-specific phospholipase D (PLD) with peak maxima 30 to 60 seconds and 5 to 7 minutes after stimulation with 20 micrograms/mL HDL3 was shown by (1) a 1.5- to 3-fold increase in Cho release, and (3) transphosphatidylation of PC to phosphatidylbutanol in the presence of 0.3% butanol. Activation of PC-specific PLD was paralleled by an activation of PC-specific phospholipase C (PLC). A significant increase in [14C]diacylglycerol (DG) was seen from 2 minutes after stimulation onward and remained for at least 2 hours. By means of butanol, the PA-phosphohydrolase (PPH) inhibitor propranolol, and the PC-PLC inhibitor D609, we demonstrated that the initial PC-derived DG formation occurred primarily by a coupled PLD/PPH pathway and that a major part of the sustained DG formation was derived directly from PC by PC-PLC. By down-regulating protein kinase C (PKC) we demonstrated that PKC activates PC-PLC and desensitizes PC-PLD at no longer incubation times. The sustained PC hydrolysis as well as HDL3-mediated PI turnover and PC resynthesis was observed on stimulation with 5 to 75 micrograms/mL HDL3, whereas the rapid activation of PC-PLD/PPH was detected only on stimulation with HDL3 at concentrations of between 10 and 75 micrograms/mL. Only the latter response could be mimicked by apolipoprotein A-I and apolipoprotein A-II proteoliposomes, and only this response was inducible by cholesterol loading. The HDL3-mediated second-messenger responses were inhibited by modification of HDL3 by tetranitromethane and could not be mimicked by protein-free liposomes. These data suggest that HDL3-induced cell signaling in human skin fibroblasts is mediated by specific protein-receptor interaction and that more than one agonist activity may be involved.

Cells, Cultured↗
PubMed1995

Lymphocytic Na(+)-H+ exchange increases after an oral glucose challenge.

The effects of oral glucose challenge on plasma glucose concentration, plasma insulin concentration, arterial blood pressure, cytosolic pH (pHi), cytosolic free Na+ concentration ([Na+]i), and cellular Na(+)-H+ exchange activity were investigated in 16 healthy subjects. The pHi, [Na+]i, and Na(+)-H+ exchange activity were measured in intact lymphocytes by using the fluorescent dye technique. The oral glucose challenge significantly increased plasma glucose, plasma insulin, and the lymphocytic Na(+)-H+ exchange activity, measured as change of pHi per second (control [0 hours], 5.20 +/- 0.53 x 10(-3) dpHi/s; 1 hour after glucose administration, 8.28 +/- 1.07 x 10(-3) dpHi/s; 2 hours after glucose administration, 8.15 +/- 1.18 x 10(-3) dpHi/s; P = .002). The lymphocytic Na(+)-H+ exchange was significantly correlated with plasma glucose concentration (r = .357, P = .041). During steady state euglycemic hyperinsulinemic clamp, the Na(+)-H+ exchange activity was not significantly changed compared with baseline values. The study shows that changes of blood glucose levels can induce an acute increase in Na(+)-H+ exchange activity. Systolic blood pressure and Na(+)-H+ exchange activity were significantly (P < .001) but weakly correlated during an oral glucose challenge.

Adult↗