Search PubMed⌕ Search

Biomedical subjects

A Schmidt

Publications and source records attributed to A Schmidt.

At least 307 records · Page 17Linked to original sources
PubMed1996

Proximity of iliosacral screws to neurovascular structures after internal fixation.

The placement of iliosacral screws for the stabilization of pelvic ring lesions is technically demanding. The postoperative computed tomography scans of 31 patients who had 57 iliosacral screws placed for various indications were studied to determine the proximity of these screws to neurovascular structures. The closest distance of the screws from the S1 foramen averaged 3 mm. (range, 0-10.5 mm); the average closest distance to the anterior cortex of the sacral ala was 4.8 mm (range, 0-15.3 mm). The corridor for the insertion of the screws between the S1 foramen and the anterior cortex of the sacrum averaged 21.7 mm (range, 16.2-28.9 mm). Trigonometric analysis of these dimensions suggests that deviations of the surgeon's hand by as little as 4 degrees may direct iliosacral screws either into the S1 foramina or through the anterior cortex of the sacrum.

Bone Screws↗
PubMed1996

Diagnostic results in animal dermatophytoses.

Superficial mycoses caused by dermatophytes, as well as asymptomatic carriership of dermatophytes, have a high prevalence among domestic animals and pets. We examined 606 clinical specimens from skin lesions of animals with a significant tendency towards superficial mycosis due to their clinical features. Samples were obtained from horses, dogs, cats, small rodents, birds, and rabbits. The specimens were examined by microscopic and cultural techniques. Microscopically, there was no significant difference in the prevalence of structures which may develop fungal elements between the groups culturally positive or negative for dermatophytes and yeasts. Overall, 24.6% of the samples were microscopically positive. In specimens obtained from horses, a high contamination rate of 36%, mostly due to moulds, was found with a cycloheximide supplemented medium, making the examination of these cultures for the growth of dermatophytes impossible. The other animals showed a significantly lower contamination rate, 11% on average. In horses, Trichophyton equinum had the highest prevalence, in small rodents. Trichophyton mentagrophytes, and in cats Microsporum canis. Overall, 10% of the culturally examinable samples were positive for dermatophytal or yeast growth, though yeasts had only a very low isolation frequency.

Animals↗
PubMed1996

Cometabolic transformation and cleavage of nitrodiphenylamines by three newly isolated sulfate-reducing bacterial strains.

Three sulfate-reducing bacterial strains (Desulfovibrio sp. strain SHV, Desulfococcus sp. strain WHC, and Desulfomicrobium sp. strain WHB) with the capacity to cometabolize 2-nitrodiphenylamine, 4-nitrodiphenylamine, and 2,4-dinitrodiphenylamine were newly isolated. Before breaking down the diphenylamine structure, these strains cometabolically reduce the nitrodiphenylamines to the corresponding aminodiphenylamines during anaerobic oxidation of the growth substrate lactate (Desulfovibrio strain SHV and Desulfomicrobium strain WHC) or benzoate (Desulfococcus strain WHB), leading to the formation of aniline and a smaller quantity of methylaniline. These compounds were not further metabolized by the sulfate reducers. The anaerobic metabolism of aminodiphenylamines also led to the formation of heterocyclic condensation products such as phenazine and acridine derivatives, provided that they contained an amino group in the ortho position of the diphenylamine (e.g., 2-aminodiphenylamine or 2,4-diaminodiphenylamine). In addition, low levels of indole and benzothiazole derivatives were identified, but these also were not further metabolized by the three sulfate-reducing strains.

Journal Article↗
PubMed1996

Selenium radiography versus storage phosphor and conventional radiography in the detection of simulated chest lesions.

PURPOSE: To compare selenium detectors with three conventional and digital detector systems for the detection of simulated pulmonary lesions. MATERIALS AND METHODS: Templates containing nodules, linear structures, and micronodular opacities were superimposed over an anthropomorphic chest phantom. The authors compared lesion detection with use of storage phosphor radiography (250 speed), selenium radiography (250 speed) with an antiscatter grid, selenium radiography (450 speed) without an antiscatter grid, an asymmetric screen-film system (400 speed), and a conventional screen-film system (250 speed). Detection performance of 10 radiologists was compared by using a multireader-multicase receiver operating characteristic analysis of variance. RESULTS: For the detection of nodules, no statistically significant differences between imaging modes were seen. For the detection of micronodules and linear lesions, both selenium techniques were superior to all other modes (P < .05). In addition, the asymmetric screen-film radiographs were inferior (P < .05) to the conventional screen-film radiographs and to storage phosphor radiographs for the detection of micronodules. CONCLUSION: The selenium detector improves detection of simulated fine linear and low-contrast micronodular details and appears to be superior to other detector systems for chest radiography.

Humans↗
PubMed1996

Heparin-induced overexpression of basic fibroblast growth factor, basic fibroblast growth factor receptor, and cell-associated proteoheparan sulfate in cultured coronary smooth muscle cells.

Basic fibroblast growth factor (bFGF), a potent mitogen for arterial smooth muscle cells (SMCs), plays a pivotal role in the pathogenesis of arteriosclerosis and restenosis. Heparin in nanogram quantities may promote or even be required for binding of bFGF to its cognate receptor. Conversely, heparin in microgram doses is a strong inhibitor of arterial SMC replication in vitro and in vivo. Bovine coronary SMCs (cSMCs) express bFGF, bFGF receptor (FGF-R1), and cell membrane-integrated proteoheparan sulfate (HSPG). These three molecules are known to form a trimolecular complex that promotes signal transduction and mitogenesis. The bFGF synthesized by cSMCs is distributed to an intracellular and a pericellular compartment. Resting cultured cells retain about 80% of their bFGF intracellularly; 20% is found in the pericellular region. During proliferation, 70% to 80% of total bFGF is expressed in the pericellular compartment. Trypsinization generates soluble forms of the complex of bFGF with the ectodomains of the bFGF receptor and cell membrane-integrated HSPG in the pericellular compartment, thus allowing quantification of pericellular bFGF by a highly specific enzyme immunoassay. Standard heparin inhibits the proliferation of cSMCs by up to 80% in a concentration range between 10 and 100 micrograms/mL medium in a dose-dependent manner but increases the protein content of cSMCs compared with proliferating control cells. The heparin-induced increase in cellular protein content includes a 60% to 100% increase in the expression of pericellular bFGF, FGF-R1, and cell membrane-integrated HSPG. Thus, under heparin treatment, the heparan sulfate side chains of cell membrane-integrated HSPG incorporate more [35S]sulfate, and the proportion of [35S]heparan sulfate among total glycosaminoglycans increases from 36% to 52%. Fluorescence-activated cell sorting analysis and [3H]thymidine incorporation experiments provide evidence for multiple effects of heparin, including blocks at early and late checkpoints of the cell cycle in heparin-treated cells. These results indicate that heparin, despite its anti-proliferative potency, stimulates the expression of all components of the bFGF system even in coronary SMCs in which growth is inhibited.

Animals↗
PubMed1996

Angiotensin-converting enzyme polymorphism in patients with terminal renal failure.

An insertion/deletion polymorphism has been described for the gene that encodes the angiotensin-converting enzyme. The deletion allele is associated with higher angiotensin-converting enzyme plasma levels, which ultimately might lead to increased angiotensin II concentrations. Because angiotensin II is a mediator for progressive renal injury, this study determined the frequency of distribution of the angiotensin-converting enzyme insertion/deletion polymorphism in 106 hemodialysis patients and in a group of 95 healthy control patients. There was no difference between the two groups as far as the distribution of the insertion and deletion allele was concerned. Of the total hemodialysis population, 26.4% exhibited the deletion/deletion genotype, as compared with 37.9% of the healthy control population. Also, when patients with terminal renal failure as a result of glomerular disease were analyzed separately, the frequency of the deletion/deletion genotype was identical to that of the control group. Furthermore, the frequency of hypertension, coronary artery disease, left ventricular hypertrophy, and dilated cardiomyopathy, were analyzed according to the angiotensin-converting enzyme genotype, but the deletion allele could not be defined as a risk factor in the study's hemodialysis population. It was therefore concluded that the angiotensin-converting enzyme insertion/deletion polymorphism is not a major risk factor for development of end-stage renal failure. Additionally, in hemodialysis patients, there is no association between the risk for cardiovascular diseases and the angiotensin-converting enzyme genotype.

Adult↗
PubMed1996

Symptom reporting and interoceptive attention in panic patients.

The present study investigated whether bodily sensations reported by panic-disorder patients can be due to interoceptive attention. The attention of two groups, one of 16 panic patients and one of 17 normal control subjects was manipulated towards and away from bodily sensations. After each manipulation they had to report the sensations experienced. As expected, panic patients did report more sensations than controls in a baseline condition but against the hypothesis that a ceiling effect would occur in the panic group, both panic patients and controls reported more sensations after being instructed to attend to them. However, when their attention was diverted, panic patients showed a decrease in sensations greater than control subjects showed. The findings suggest that interoceptive attention may partly account for the sensations reported by panic patients.

Adult↗
PubMed1996

Two- and three-dimensional imaging for interventional MRI and CT guidance.

Minimally invasive techniques using endoscopes for image guided therapy are common in the surgical field and in internal medicine. Interventional procedures in the past were performed with either fluoroscopic, sonographic or CT-guidance, but now MRI-guided interventional procedures are being developed. Combining these technologies will improve surgical access and reduce complications. Today, tomographic 2 D and 3 D imaging (CT, EBT, MRI) can be used for precise and transparent guidance of endoscopes and surgical instruments inside the body for the field of minimally invasive therapy. 3 D imaging is helpful for anatomical, but not for morphological understanding. It has to be used interactively with actual cross sectional imaging for instrument guidance. This will offer a safe and effective access into the body, especially in high risk areas and lead to the new field of "Surgical Tomography".

Endoscopes↗
PubMed1996

In vitro susceptibility of Malassezia furfur.

Malassezia (M.) furfur is an anthropophilic fungus with complex growth requirements. Apart from its physiological appearance on human skin it is the causative agent of several skin disorders. A method for in vitro antifungal susceptibility testing of M. furfur in a microtiter plate assay has been developed. Read-out was performed colorimetrically in modified Leeming-Notman medium after incubation with alamarBlue. Twenty-two strains of M. furfur were tested, minimum inhibitory concentrations (MICs) were determined for climbazole, piroctone-olamine, selenium disulfide, zinc pyrithione. These substances are of common use in topical therapy of M. furfur-associated skin conditions. For climbazole, the range of MICs was between < 0.03 and 2 micrograms/ml with an empirical median mean of 0.03 micrograms/ml. For piroctoneolamine the range of MICs was between 16 and 64 micrograms/ml (mean = 64 micrograms/ml), for selenium disulfide between 2 and 64 micrograms/ml (mean = 8 micrograms/ml), and for zinc pyrithione between 0.12 and 8 micrograms/ml (mean = 1 micrograms/ml). These data indicate the high in vitro activity of climbazole against M. furfur, followed by zinc pyrithione. Selenium disulfide and piroctone-olamine were less active.

Antifungal Agents↗
PubMed1996

The Dornier-Lithotripter U30. First clinical experience.

OBJECTIVE: It can be claimed that ESWL is an optimal alternative for ablation of calculi by external shock waves. The new developments in ESWL have focussed more on the economic aspects of treatment rather than enhancing its efficacy or reducing the side effects. Since August 1993, the prototype of the Dornier Lithotripter U-30 was used at the Department of Urology of the Katharinen hospital in Stuttgart. METHODS/RESULTS: In 16 months, 1092 stones were treated requiring 1533 sessions. Complete disintegration was achieved in 84%; after 3 months' follow-up, 85.5% of the patients were stone free. CONCLUSION: The Dornier Lithotripter U-30 provides easy handling and a short learning curve and a sufficient disintegration of the stones. The device is suitable for safe and effective treatment of all urinary calculi, with special respect to in situ treatment of ureteral stones.

Equipment Design↗
PubMed1996

Expression of the adhesion molecules ICAM, VCAM, and ELAM in the arteriosclerotic plaque.

Subject of investigation was the demonstration of the different expression of ICAM-1, and VCAM in 13 complete cross sections of the Aorta abdominalis and the Arteria iliaca immediately available post operationem during the process of arteriosclerosis. With increasing severity of the arteriosclerosis, ELAM showed a decreasing expression of the endothelium of the main vessel and a moderate one of the cells in the adventitia. On the endothelium of the main vessel and the vasa vasorum, we detected ELAM-1, showing a decreasing tendency when the arteriosclerosis was aggravating. In case of severe arteriosclerosis, a focal expression was also found on cells in the intima and media. In the adventitia, the expression was relatively constant during the process of arteriosclerosis. The more serious the disease, the more provable was VCAM on endothelial cells. In cases of severe arteriosclerosis, we also detected a focal staining in deeper layers of the wall. This study supports the concept of the active role of endothelial cells in the recruitment of leucocytes during the early steps of the arteriosclerotic process. In this process, with the disease aggravating, the endothelium seems to be less significant than the smooth muscle cells, which obviously play an important role in the course of arteriosclerosis.

Aorta, Abdominal↗
PubMed1996

A fixed-dose combination of low molecular weight heparin with dihydroergotamine versus adjusted-dose unfractionated heparin in the prevention of deep-vein thrombosis after total hip replacement.

The low dose heparin regimen (LDH) is not appropriate for prevention of intra- and postoperative thromboembolic complications in high risk patients, especially those undergoing elective hip replacement. Despite LDH prophylaxis, the incidence of deep-vein thrombosis (DVT) remains in a range of 20 to 35%. Adjusted-dose unfractionated heparin prophylaxis is thought to be one of the most effective regimens for thrombosis prophylaxis in this indication, but it requires two or three daily injections as well as precise monitoring of the activated partial thromboplastin time (aPTT). As an attractive alternative, we investigated the efficacy and safety of the low molecular weight heparin (LMWH) certoparin combined with dihydroergotamine (DHE) given once daily. In a randomised, open clinical trial, a total number of 305 patients undergoing total elective hip replacement were enrolled and divided into two groups, either receiving a fixed-dose combination of LMWH (3,000 IU) and DHE (0.5 mg) subcutaneously once daily, or adjusted-dose unfractionated heparin (UFH) subcutaneously every 8 h. The UFH dosage was adjusted daily to keep an aPTT of about 50 s. The aPTT was determined 3 h after the morning injection. During the study, the starting dose (15,000 IU/day) was increased to a plateau value of 28,800 +/- 7,150 IU/day (mean +/- SD) to maintain the aPTT in the prescribed range. The plateau value was achieved after 8 postoperative days. For analysis of efficacy 289 patients were evaluable. The occurrence of deep vein thrombosis was determined by bilateral ascending venography, which was performed on the same day in patients with clinical signs suggesting DVT; and in all remaining patients at the end of the prophylaxis period. Deep vein thrombosis was diagnosed in 17 of 142 patients (12.0%) treated with LMWH/DHE and in 13 of 147 patients (8.8%) treated with adjusted-dose UFH. Combined distalproximal thrombosis was more frequently in patients receiving UFH (n = 5; 3.4%) compared to the LMWH/DHE group (n = 2; 1.4%). These differences are statistically not significant. In the UFH group one case of non-fatal pulmonary embolism occurred. Both prophylaxis regimens were well tolerated; wound bleeding was observed in 8 (5.3%) patients in the LMWH group and in 6 (4.0%) patients in the UFH group. Intraoperative blood-loss volume (mean +/- SD) was 751 +/- 339 mL (LMWH/DHE) and 736 +/- 380 mL (UFH), whereas postoperative drain-loss volume (mean +/- SD) was found to be 523 +/- 333 mL (LMWH/DHE) and 581 +/- 404 mL (UFH). Whole blood transfusion volumes (mean +/- SD) were 570 +/- 202 mL (LMWH/DHE) and 748 +/- 455 mL (UFH). Additionally, red cell replacement volumes (mean +/- SD) were 804 +/- 435 mL (LMWH/DHE) and 720 +/- 328 mL (UHF). Revision of wound or additional drainage were necessary in 3 LMWH/DHE and 7 UFH patients. One patient needed reoperation due to bleeding, 3 (2.0%) had petechia and 1 exhibited an allergic exanthema, all of them in the UFH group. A slight erythema at the injection site was observed in 6 (3.9%) patients receiving LMWH/DHE. During the course of prophylaxis, injection hematomas were documented in 57.9% (LMWH/DHE) and in 61.4% (UFH) of the patients. All differences were statistically not significant. Single daily subcutaneous injections of LMWH/DHE appeared to be safe and efficacious compared to adjusted-dose UFH for prophylaxis of DVT in high-risk patients.

Aged↗
PubMed1996

Nuclear accumulation and homeostasis of the unusual polymer beta-poly (L-malate) in plasmodia of Physarum polycephalum.

The plasmodium of Physarum polycephalum specifically contains an unusual polyester, beta-poly(L-malate), which is not found in any of the mononucleate forms of its life cycle. Plasmodia growing on D-glucose have been analyzed for beta-poly(L-malate) in nuclei, cytosol and culture medium after cell fractionation, purification by chromatography on DEAE-cellulose and digestion of proteins/nucleic acids. Nuclei contained 400 micrograms polymer per 1 g of plasmodia, corresponding to a nuclear concentration of 230 mM L-malyl residues, not depending on growth rates, lengths of growth periods, and the growth form as micro- or macroplasmodia. The synthetic rate increased during the phase of rapid enlargement of the nuclei after mitosis. Beta-Poly(L-malate) was polydisperse in molecular mass, these tending to be higher in nuclear than in cytosolic extracts and being lowest in the culture medium. Beta-Poly(L-malate) was not degraded when contained in plasmodia, in contrast to degradation and the occurrence of low molecular mass polymer in the culture medium. During pulse-chase feeding with D-[14C]glucose (0.8 micrometerCi/mol), beta-[14C]poly(L-malate) appearance followed kinetics indicating a release of polymer from nuclei into the culture medium when it was in excess of a threshold. Injection experiments with purified beta-[14C]poly(L-malate) revealed a re-entry from the cytoplasm into the nuclei and thus the possibility of commutation between the cytoplasm and the nuclei. The observed homeostasis in nuclei supports the assumption that beta-poly(L-malate) plays an essential role in growing plasmodia.

Animals↗
PubMed1996

[Renal side effects of angiotensin converting enzyme inhibitors].

Angiotensin converting enzyme (ACE) inhibitors are used widely in the treatment of hypertension and congestive heart failure. An increasing number of patients with chronic renal failure is treated with ACE inhibitors because of their antiproteinuric effect. In patients with diabetic nephropathy ACE inhibitors also slow the progression of renal failure. Direct drug related nephrotoxic effects, like the induction of proteinuria, glucosuria or an interstitial nephritis are rare events. The often observed reduction of the glomerular filtration rate after the induction of an ACE inhibitor therapy is due to the specific intrarenal action of these agents and therefore not an adverse drug reaction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Basic fibroblast growth factor controls the expression and molecular structure of heparan sulfate in corneal endothelial cells.

Cultured bovine corneal endothelial cells express 5-8 ng basic fibroblast growth factor (bFGF)/mg cell protein and distribute it between the intracellular and pericellular compartment. Confluent cultures retain approximately 80% of the total bFGF intracellularly, whereas 20% is present in the pericellular (trypsin-releasable) compartment. No bFGF can be detected in the culture medium. The presence of 1-2 ng/ml medium of endogenous or exogenous (human recombinant) bFGF is sufficient to support cell growth. Simultaneously, cells incorporate [35S]sulfate and [3H]glucosamine into the sulfated proteoglycans associated with the cell layer at a rate that is three times higher than in the absence of bFGF. The enhanced proteoglycan synthesis is accompanied by a shift in proteoglycan distribution. In control cells, cell-associated heparan sulfate accounts for about 30% of the total glycosaminoglycans, whereas under the influence of bFGF the amount of heparan sulfate increases to approximately 60%. At the same time, the molecular structure of the heparan sulfate molecule undergoes bFGF-specific changes as indicated by the [35S]oligosaccharide pattern generated by heparitinase I degradation. The proportion of [35S]oligosaccharides with greater than six monosaccharides decreases on account of disaccharides and tetrasaccharides under the influence of bFGF. Pretreatment of bFGF with neutralizing antibodies against bFGF abolishes its biological activity. The results suggest a bFGF-dependent change in the rate of synthesis and structural features of the membrane-associated heparan sulfate in corneal endothelial cells. The modification of the heparan sulfate structure could influence its bFGF-binding and antiproliferative activity.

Animals↗
PubMed1995

[Residual postoperative pneumothorax: harmless radiological finding or complication-prone diagnosis?].

470 patients underwent either lobectomy, bilobectomy or decortication at our institution between 1980 and 1991. A residual postoperative pneumothorax was observed in 20.7% of the patients at discharge after removal of the chest tubes. There was no significant correlation between the development of a residual postoperative pneumothorax and the patient's age and gender, the type of operation (lobectomy vs bilobectomy vs decortication) and the date of operation (as related to the introduction of stapling devices). This residual postoperative pneumothorax at discharge resolved without any further treatment in 95% of the patients during follow-up. Complete regression was observed in 91% of the patients within one year after the operation and the duration of regression did not correlate with the size of the pneumothorax at discharge. No empyema was observed in any patient with residual pneumothorax during follow-up, which also holds true for patients who underwent resection or decortication for inflammatory disease. We conclude that there is no need for treatment of residual postoperative pneumothorax, either with space-filling maneuvers at the initial operation or repeat chest tube insertions during follow-up, provided there is no evidence of lung collapse.

Female↗
PubMed1995

Activator carbamino carbon to inhibitor phosphorus internuclear distances in ribulose-1,5-bisphosphate carboxylase/oxygenase. A solid-state NMR study.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is a hexadecamer of approximately 550 kDa in most organisms. Rotational-echo double-resonance (REDOR) and transfer-echo double-resonance (TEDOR) solid-state NMR were used to obtain the average internuclear distance between the 99% 13CO2-labeled activator carbamino carbon to the phosphate phosphorus nuclei of active-site-bound 2-carboxy-D-arabinitol 1,5-bisphosphate (CABP), in freeze-quenched, lyophilized samples of confrey Rubisco. The distance 7.5 +/- 0.5 A determined by solid-state NMR is in agreement with the distance of 7.7 A inferred from the crystal-structure coordinates for spinach Rubisco-CABP-CO2-Mg2+ quaternary complex.

Binding Sites↗