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B Luther

Publications and source records attributed to B Luther.

At least 19 recordsLinked to original sources
PubMed2000

An algebraic/graphical tool to compare ecosystems with respect to their pollution V: cluster analysis and Hasse diagrams.

In case of large data matrices comparative evaluations of objects/regions with the technique of Hasse diagrams may be troublesome due to a messy system of lines in the graphical representation. Here fuzzy clustering leads to useful simplifications because regions with slightly different pollution pattern are grouped together. However, fuzzy clustering implies to introduce a threshold value for the membership of an object to a cluster and to select the best number of clusters. Therefore many arbitrarities evolve. Within the systematic study presented here we found that some objects are very stable against variations of the threshold value and the number of cluster whereas other objects behaves different. According to their behaviour we investigated a classification of the objects. Formal Concept Analysis shows that in some cases specific pollution pattern imply the membership to one of these classes. For example objects which are characterized by high Pb-, Zn-concentration and moderate S-concentration imply a high stability against variants of the clustering process. Further implications are described in the paper.

Cadmium↗
PubMed2000

Surgical treatment of 50 carotid dissections: indications and results.

PURPOSE: This article analyzes the course of 48 patients with 49 chronic carotid dissections (who were treated surgically at our institution after a median anticoagulation period of 9 months because of a persistent high-grade stenosis or an aneurysm) and the course of one additional patient with acute carotid dissection (who underwent early operative reconstruction 12 hours after onset because of fluctuating neurologic symptoms). METHODS: All medical and surgical records and imaging studies were reviewed retrospectively. All histologic specimens were reevaluated by a single pathologist to assess the cause of dissection. Follow-up of 41 patients (85%) after 70 months (range, 1-190 months) consisted of an examination of the extracranial vessels in the neck by Doppler ultrasound scanning and a questionnaire about the patients' medical history and their personal appraisals of cranial nerve function. RESULTS: Seventy percent of the dissections had developed spontaneously; 18% were caused by trauma; 12% of all patients (22% of the women) had a fibromuscular dysplasia. Indication for surgery was a high-grade persisting stenosis and a persisting or newly developed aneurysm. Flow restoration was achieved by resection and vein graft replacement in 40 cases (80%) and thromboendarterectomy and patch angioplasty in three cases (6%). Gradual dilatation was performed and effective in two cases (4%). Five internal carotid arteries (10%) had to be clipped because dissection extended into the skull base. One patient died of intracranial bleeding. Five patients (10%) experienced the development of a recurrent minor stroke (ipsilateral, 4 patients; contralateral, 1 patient). Cranial nerve damage could not be avoided in 29 cases (58%) but were transient in most of the cases. During follow-up, one patient died of unrelated reasons, and only one patient had experienced the development of a neurologic event of unknown cause. CONCLUSION: Chronic carotid dissection can be effectively treated by surgical reconstruction to prevent further ischemic or thromboembolic complications, if medical treatment for 6 months with anticoagulation failed or if carotid aneurysms and/or high-grade carotid stenosis persisted or have newly developed.

Anticoagulants↗
PubMed1999

[Controlled reperfusion of ischemic extremity musculature to prevent free radical induced lesions].

Tissue injury following reperfusion represents an essential problem of reconstructive vascular surgery. Pathogenetically toxic oxygen radicals are considered to play a pivotal role. Pharmacotherapeutical approaches are based particularly on antioxidants and vasodilators. However, a standardized regimen is not yet clinically introduced. In 48 adult Lewis-rats lower limb ischemia was induced by aortal cross-clamping. Following 3.5 hours of ischemia intravascular flushing perfusion via the distal aorta with a heparinized electrolyte solution (group B). Group C received additionally oxypurinol, group D alprostadil and group E sodium selenite into the flushing solution. At 4 hours recirculation was established. After 10 min, 30 min and 24 hours of reperfusion we determined lactate, creatine kinase, lactate dehydrogenase, urea, malondialdehyde and the laser Doppler flux. At the end of the experiments biopsies were taken from M. tibialis anterior. In comparison to control animals (group A) we observed an attenuation of reperfusion injury in the groups treated with flushing perfusion. Free oxygen radical reactions measured by malondialdehyde release were significantly reduced (30 min: A-209.1 +/- 45.4, B-127.3 +/- 36.9, C-113.2 +/- 14.1, D-99.6 +/- 24.5, E-123.6 +/- 11.2 mmol/l, p < 0.05). The laser Doppler flux measurements corresponded with the biochemical analyses (30 min: A-52.4 +/- 11.1, B-48.0 +/- 11.0, C-72.6 +/- 12.0, D-74.4 +/- 13.3, E-62.6 +/- 10.8% of baseline). Histologically, treatment with alprostadil (PGE1) and oxypurinol revealed superior results. Standardized intraarterial flushing perfusion with antioxidants and vasodilators reduces reperfusion injury. Clinical trials are urgently required to confirm the experimental findings and to optimize the therapy of extremity ischemia/reperfusion injury in humans.

Animals↗
PubMed1998

Reference typing report for complement component C4.

During the 7th Complement Genetics Workshop, Mainz, Germany, May 1998, a complement component C4 typing exercise took place with the aim of applying present technologies to the definition of reference C4 alleles/phenotypes and the recognition of nonexpressed (Q0) C4 alleles within expressed haplotypes. Eleven samples were submitted from 3 laboratories and tested by 14 participating laboratories with basic protein-typing technologies; in addition, each laboratory contributed data from local expertise. The samples were introduced to the reference typing for one or more characteristic allotype or for partial or total nonexpression of one isotype. The blinded samples were centrally evaluated and the results discussed among the participants at a plenum meeting. From the results, the samples could be classified into a group of common, easy to diagnose pheno-/allotypes, less common but still unanimously recognised variants, and a third group with difficult pheno-/allotypes. Within the latter group, the allotypes were either new (C4A '92'; C4B '93') and/or showed partial or total reversed antigenicity and unusual Rodgers/Chido (Rg/Ch) PCR subtypes (C4A '92'; C4A 12; C4B '35'; C4B '13'). Semiquantitative C4-alpha-chain estimates of relative isotype levels correlated well with the number of alleles seen at each locus by agarose gel electrophoresis, and were superior to other isotype quantitation methods. From the evaluation of the reference typing it was concluded that the recognition of rare, aberrant or hybrid C4 alleles with partial or total reversed Rg/Ch antigenicity or monoclonal reactivity is still difficult in most instances; besides isotype-dependent lysis, relative migration values, immunoblots with Rg- and Ch-specific monoclonal antibodies, Rg/Ch PCR typing, side-by-side comparison with already described allotypes will ultimately be required. The recognition of nonexpressed alleles within C4A and C4B expressed phenotypes remains the major obstacle in C4 genetic typing. Finally, a conclusive interpretation of DNA typing results will be achieved only in the context of complete allotyping results at the protein level, and at present cannot replace conventional protein allotyping.

Alleles↗
PubMed1997

[Aortic aneurysm in horseshoe kidney--special diagnosis and therapy].

The co-existence of horseshoe kidney (HSK) and abdominal aortic aneurysm (AAA) is rare and demands a special diagnostic workup and a meticulous surgical procedure. Ten patients with HSK associated with AAA are reported. All underwent aortic replacement with successful preservation of multiple renal arteries. One patient died at the 7th postoperative day from myocardial infarction. HSK does not represent a contraindication for aortic repair. Angiography for identification of aberrant renal arteries and classification into three types for surgical management is mandatory. In type I and II we recommend a standard midline transperitoneal approach. Only in type III does a thoraco-abdominal approach seem favourable. The aortic reconstruction should be performed with tube grafts, if possible. Aberrant renal arteries are reattached directly to the prosthesis. Dissection of renal isthmus should be avoided. Temporary cold renal perfusion is indicated to extend the ischemic tolerance time. As repair of a ruptured AAA in patients with HSK may be quite difficult and time consuming, we recommend more liberal indications for aneurysm surgery in patients with HSK.

Adult↗
PubMed1996

[Perioperative intra-arterial irrigation perfusion for adjuvant therapy of acute intestinal circulatory disorders].

The extent of mesenteric infarctions caused by intestinal circulation disorders essentially depends on reactive vasoconstriction and oxygen radical induced lesions of enteric mucosa. Animal experiments indicated protective effects of an intraarterial flushing perfusion of mesenteric arteries with vasodilators and anti-oxidants. We carried out a transaortic perfusion of the superior mesenteric artery with lactated Ringer's-solution and vasodilators (papaverin, tolazolin, PGE1) in acute occlusion of mesenteric arteries in 12 patients (case reports). Three patients were treated successfully without reconstruction by conservative method alone. Only one patient (8.33%) died because of uncontrolled enteric ischemia. Angiological therapy is necessary in modern treatment of acute mesenteric ischemia. Surgical goals are elimination of central vascular occlusions and resection of necrobiotic areas of intestinal organs.

Aged↗
PubMed1996

[Pharmacologic modification of intestinal reperfusion injury in the animal experiment].

We evaluated experimentally (80 Lewis-rats) possible pharmacological strategies in the treatment of intestinal reperfusion injury in hypo- and normothermia. We used a specific perfusion solution containing PGI2 or radical scavengers (superoxide dismutase, oxypurinol, tocopherol, ascorbate). Decreased malondialdehyde (MDA) plasma release after reperfusion proved the antioxidative efficiency of the administered radical scavengers (normothermia-control group: MDA increase after 15 min of reperfusion to 160 +/- 30% compared to level at the end of ischemia, oxypurinol: 110 +/- 23%, tocopherol: 112 +/- 12%, ascorbate: 104 +/- 20%; p < 0.05). The ATP/ADP-ratio of the therapy groups was stable in contrast to the control group. Alkaline phosphatase release was significantly diminished under radical scavenger administration (normothermia/15 min reperfusion-control group: 7.7 +/- 0.9 mumol/ls, oxypurinol: 4.4 +/- 0.4 mumol/ls, tocopherol: 3.5 +/- 0.1 mumol/ls, ascorbate: 5.9 +/- 0.3 mumol/ls; p < 0.05). Histologically we observed a mucosa protective effect particularly in the ascorbate group. Other pharmacological strategies are discussed.

Animals↗
PubMed1996

[Vascular surgery operations in tumor diseases].

In a retrospective analysis covering 10 years, we examined 53 patients with malignant tumors, who had undergone 74 vascular reconstructive operations. The rate of all complications was 40%. Thirty-two patients died within a period of 3.1 years because their tumor progression; the survival rate after an average of 6.9 years was 65.6%.

Aortic Aneurysm, Abdominal↗
PubMed1995

Perioperative vascular flushing perfusion in acute mesenteric artery occlusion.

AIM: To evaluate in animals and patients a perioperative vascular flushing perfusion with antioxidants in order to improve postischaemic condition of the bowel and hence, to prolong the warm ischaemia tolerance time. MATERIALS: 40 rats and 10 patients with acute mesenteric artery occlusion. METHODS: Intestinal ischaemia was induced in 40 rats by clipping the superior mesenteric artery for 1 h. Thirty animals received a vascular flushing perfusion with oxygen radical scavengers (ascorbate, tocopherol or oxypurinol). Histology, ATP, ADP levels were examined in tissue biopsies and malondialdehyde, lactate dehydrogenase, alkaline phosphatase levels were measured in blood during ischaemia and 60 min after reperfusion. RESULTS: ATP restoration was particularly improved in the oxypurinol group (ATP/ADP-ratio = 2 vs. 1.2 in the control group). Malondialdehyde increase observed after reperfusion as a marker of radical induced lipid destruction was significantly attenuated (control group 160% of base level vs. 127% in the ascorbate group, 133% in the tocopherol group, 121% in the oxypurinol group). Histological alterations during ischaemia/reperfusion were markedly less extensive in the perfusion groups than in control. The patients treated perioperatively with arterial flushing perfusion had an overall mortality of 10%. CONCLUSION: Vascular flushing perfusion with oxygen radical scavengers prevents radical induced ischaemic damage and may prolong the warm ischaemic tolerance time of the intestine.

Acute Disease↗
PubMed1993

Monoclonal antibodies with in vitro borreliacidal activities define the outer surface proteins A and B of Borrelia burgdorferi.

Thirteen monoclonal antibodies (mAb) were produced against Borrelia burgdorferi strains B31 and PKa. Five mAb recognized the outer surface protein OspA (relative molecular mass (M(r)) 31,000) and four OspB with an M(r) of 34,000. Two of these mAb were directed against flagellin with an M(r) of 41,000, and the remaining two against the antigens of B. burgdorferi with M(r) values of 19,000 and 17,000. Immunoblot and immunofluorescence studies with these mAb on five isolates of B. burgdorferi revealed differences in the individual antigenic epitopes of OspA and OspB. OspA and OspB specific mAb showed a borreliacidal activity in vitro. These antibodies were additionally reactive in haemagglutination and immunofluorescence assays. Enzymatic digestion investigations on intact borreliae suggest that the antigenic determinants of mAb with borreliacidal activity are located in the peptide chain of OspA and OspB.

Animals↗