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Biomedical subjects

S Schmidt

Publications and source records attributed to S Schmidt.

At least 199 records · Page 11Linked to original sources
PubMed1999

Transmyocardial laser revascularisation compared with continued medical therapy for treatment of refractory angina pectoris: a prospective randomised trial. ATLANTIC Investigators. Angina Treatments-Lasers and Normal Therapies in Comparison.

BACKGROUND: Transmyocardial revascularisation (TMR) is an operative treatment for refractory angina pectoris when bypass surgery or percutaneous transluminal angioplasty is not indicated. We did a prospective randomised trial to compare TMR with continued medication. METHODS: We recruited 182 patients from 16 US centres with Canadian Cardiovascular Society Angina (CCSA) score III (38%) or IV (62%), reversible ischaemia, and incomplete response to other therapies. Patients were randomly assigned TMR and continued medication (n=92) or continued medication alone (n=90). Baseline assessments were angina class, exercise tolerance, Seattle angina questionnaire for quality of life, and dipyridamole thallium stress test. We reassessed patients at 3 months, 6 months, and 12 months, with independent masked angina assessment at 12 months. FINDINGS: At 12 months, total exercise tolerance increased by a median of 65 s in the TMR group compared with a 46 s decrease in the medication-only group (p<0.0001, median difference 111 s). Independent CCSA score was II or lower in 47.8% in the TMR group compared with 14.3% in the medication-only group (p<0.001). Each Seattle angina questionnaire index increased in the TMR group significantly more than in the medication-only group (p<0.001). INTERPRETATION: TMR lowered angina scores, increased exercise tolerance time, and improved patients' perceptions of quality of life. This operative treatment provided clinical benefits in patients with no other therapeutic options.

Aged↗
PubMed1999

Metabolism of phenylbenzoate by Pseudomonas sp. strain TR3.

A bacterial isolate, tentatively identified as Pseudomonas sp. strain TR3, was found to utilize the diaryl ester phenylbenzoate as sole source of carbon and energy. This strain has the ability to productively degrade phenylbenzoate and some substituted derivatives by a catabolic sequence which was characterized biochemically. The biodegradation of phenylbenzoate is thus initiated by an inducible esterase, effectively hydrolyzing the diaryl esters to produce stoichiometric amounts of two monoaromatic metabolites, identified as benzoate and phenol in the case of phenylbenzoate. The diaryl ester p-tolylbenzoate was hydrolyzed to yield benzoate and 4-methylphenol while 4-chlorophenylbenzoate gave rise to the production of benzoate and 4-chlorophenol. These monoaromatic catabolites were further degraded via the oxoadipate pathway.

Benzoates↗
PubMed1999

Lethal capillary leak syndrome after a single administration of interferon beta-1b.

Interferon beta-1b (IFNbeta-1b) is a potent immunomodulatory drug in the treatment of MS. We report a lethal capillary leak syndrome after the administration of IFNbeta-1b in a patient with disseminated white matter disease, monoclonal gammopathy, and acquired C1 inhibitor (C1-INH) deficiency. IFNbeta-1b may cause a transient release of proinflammatory cytokines finally resulting in an uninhibited activation of the complement cascade in patients with C1-INH deficiency.

Adult↗
PubMed1999

18F-deoxyglucose positron emission tomography (FDG-PET) for the planning of radiotherapy in lung cancer: high impact in patients with atelectasis.

PURPOSE: 18F-deoxyglucose positron emission tomography (FDG-PET) is increasingly applied in the staging of lung cancer (LC). This study analyzes the potential contribution of PET in radiotherapy planning for LC with special respect to tumor-associated atelectasis. METHODS AND MATERIALS: Thirty-four patients with histologically confirmed LC, who had been examined by PET during pretreatment staging, were included. All were irradiated after CT-based therapy planning with anterior/posterior (AP) portals encompassing the primary tumor and the mediastinum (CT portals, CP). The result of the PET examination was unknown in treatment planning. In retrospect, a PET portal (PP) was delineated and compared with the CP. RESULTS: In 12/34 cases, the shape and/or size of the portals were changed, primarily (n = 10) the size of the fields was reduced. The median area of CP was 182 cm2 versus 167 cm2 of PP. Seventeen of 34 patients had dys- or atelectasis caused by a central primary tumor. In these cases, differences between CP and PP were significantly more frequent than in the other patients (8/17 vs. 3/17, p = 0.03). CONCLUSION: In this retrospective analysis, the information provided by FDG-PET would have contributed to a substantial reduction of the size of radiotherapy portals. This applies particularly for patients with tumor-associated dys- or atelectasis.

Carcinoma, Non-Small-Cell Lung↗
PubMed1999

Imaging protein kinase Calpha activation in cells.

Spatially resolved fluorescence resonance energy transfer (FRET) measured by fluorescence lifetime imaging microscopy (FLIM), provides a method for tracing the catalytic activity of fluorescently tagged proteins inside live cell cultures and enables determination of the functional state of proteins in fixed cells and tissues. Here, a dynamic marker of protein kinase Calpha (PKCalpha) activation is identified and exploited. Activation of PKCalpha is detected through the binding of fluorescently tagged phosphorylation site-specific antibodies; the consequent FRET is measured through the donor fluorophore on PKCalpha by FLIM. This approach enabled the imaging of PKCalpha activation in live and fixed cultured cells and was also applied to pathological samples.

3T3 Cells↗
PubMed1999

Transcription mapping in a medulloblastoma breakpoint interval and Smith-Magenis syndrome candidate region: identification of 53 transcriptional units and new candidate genes.

The chromosomal band 17p11.2 is associated with a number of neurological disorders and malignant diseases. This region is also characterized by the presence of complex repeat elements that are probably responsible for the frequent occurrence of interstitial deletions, duplications, and isochromosome formation. In the course of the molecular analysis of this interval, an integrated map with YACs, PACs, and cosmids covering approximately 6 Mb was established. Focusing on the 1.4-Mb interval containing the Smith-Magenis syndrome critical region and the breakpoint region for medulloblastomas, we constructed a detailed transcript map between the marker PS2 and the proximal CMT1A repeat. FISH analysis of the PACs allowed determination of the position of the transcripts with respect to the SMS critical region and the presumptive chromosomal breakpoint in medulloblastomas. One PAC (G21100) provided evidence for the presence of a novel complex repeat unit, indicating that there are at least three independent repeat elements within 2 Mb. Five genes were mapped to clone G21100 and are likely to form part of this novel complex sequence repeat. In summary, 53 new transcripts were isolated by using cDNA selection and exon trapping. This included 8 known but previously unmapped genes and 45 novel transcripts. The expression profile of 21 transcripts was determined by RT-PCR. Based on their homologies to known genes or proteins, some of the novel genes are considered candidate genes either for malignant diseases or for the Smith-Magenis syndrome.

Brain Neoplasms↗
PubMed1999

Some factors affecting enantiomeric impurity determination by capillary electrophoresis using ultraviolet and laser-induced fluorescence detection.

The key factors influencing enantiomer trace determination were investigated; these include resolution capillary diameter, limit of detection, linear range and type of detection. Chiral reagents, (+)- and (-)-1-(9-fluorenyl)ethyl chloroformate (FLEC), were employed as probes to demonstrate the influence of the variables. In order to find the best resolution, separation variables were optimized in both capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) modes by the application of factorial design experiments. A highly efficient chiral separation of the (+/-)-FLEC, derivatized with nonchiral amino acids, was achieved when using gamma-cyclodextrin as the chiral selector. The benefits of using a small diameter capillary for direct determination of both (+) and (-)-FLEC impurity (0.05-0.1% area/area) were demonstrated using UV detection and applying a sample stacking condition. A frequency-doubled argon ion laser (244 nm) was used as light source for laser-induced fluorescence (LIF) detection. Excitation light was provided by means of an optical fiber directed into the Hewlett Packard 3D capillary cartridge. The signals from UV and LIF were monitored simultaneously. The application of LIF detection greatly improved sensitivity and linear range. Further, as a consequence of the increased sensitivity, sample loading could be decreased, which led to an improvement of separation efficiency. Direct determination of 0.005% impurity could be achieved within the linear range.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed1999

Systematic search for susceptibility genes in different populations.

We analyzed the first replicate of each of the four simulated population samples from three distinct populations by linkage and association genome scans and could identify three regions with susceptibility loci for the disease: on chromosome 1, marker D1G024, with strong evidence for gene x environment interaction; or chromosome 3, around marker D3G045; and on chromosome 5, markers D5G035-D5G042. Our results were obtained without knowing the true disease model and are compared with this model in the discussion.

Alleles↗
PubMed1999

Incorporating larger families in identity-by-descent based linkage analysis.

Genome scans for alcoholism susceptibility genes were carried out using identity-by-descent-based statistics for qualitative traits. We compared the results when 1) multipoint information was used for all families, where some had to be truncated, 2) multipoint information was used only for small families while large (untruncated) pedigrees were analyzed with a single-point approach, and 3) single-point analysis was used for all pedigrees. Differences between the methods were observed, but neither method could identify regions related to the susceptibility for alcoholism.

Alcoholism↗
PubMed1999

Analysis of principal component based quantitative phenotypes for alcoholism.

Principal component analysis was used to construct quantitative phenotypes for alcoholism. These were analyzed for linkage to genomic regions with a variance components approach. The four phenotypes considered were a factor describing medical symptoms of alcohol dependency, a factor describing a psychological profile correlated with susceptibility to alcoholism, monoamine oxidase B (MAOB) activity and an average measurement of the P3 component of event-related potentials (ERP) at the Fp electrode placements. One region (around marker GATA123C09 on chromosome 3) with suggestive evidence for linkage was detected for the P3 (Fp) measurement. For three of the four distinct phenotypes, modest evidence for linkage to a similar region (around marker ADH3 on chromosome 4) was found.

Alcoholism↗
PubMed1999

Preoperative assessment of mortality risk in hepatic resection by clinical variables: a multivariate analysis.

Hepatic resection is a chance for cure for primary and secondary liver tumors and a variety of benign diseases. Despite advances in surgical technique and patient care, preoperative and postoperative morbidity in patients undergoing liver resection remains high. Because a high morbidity represents a risk factor contributing to a fatal outcome of the surgical procedure, our study aimed to investigate the contribution of different risk factors to a fatal outcome and if mortality can be predicted by the presence of certain risk factors. Two hundred fifty-seven patients undergoing hepatic resection (curative and palliative) were analyzed preoperatively, immediately after surgery, and 10 days after surgery for 60 potential risk factors. Survivors (n = 238) and nonsurvivors (n = 19) were compared univariately. The analysis identified 14 variables to differentiate between groups. These variables were processed by multivariate logistic regression analysis. Three models to estimate 30-day mortality were identified, tested for statistical accuracy, and assessed for their receiver-operated characteristics (ROCs). The variables in the multivariate models were as follows: preoperatively, age, number of comorbid factors, and presence of cirrhosis; immediately after surgery, age, number of comorbid factors, and percentage of resected liver; and 10 days after surgery, age, hours of ventilation, and number of adverse events. Goodness of fit was 0. 863, 0.912, and 0.966, respectively. Areas under the ROC curves were 83.6%, 85.7%, and 98.0%. The specificity (probability to identify survivors correctly) was greater than 90% for all models, although sensitivity (probability to identify nonsurvivors correctly) was greater than 90% only for 10 days after surgery. We conclude that logistic regression is appropriate to assess the importance of risk factors in the course of hepatic resection and to identify patient groups at high risk.

Female↗
PubMed1999

A comparison of two controlled-release delivery systems for the delivery of amiloride to control angiogenesis.

The diuretic amiloride has been reported to inhibit both Na+-H+ antiport and the urokinase-type plasminogen activator. As a consequence of these inhibitions, neovascularization may also be inhibited. We hypothesized that if amiloride could be effectively delivered in a site-specific manner, a system might be developed that could inhibit localized angiogenesis. In order to evaluate this possibility we conducted a study that compared two different controlled-release systems into which amiloride had been incorporated. The effectiveness of amiloride release from each delivery system was determined by quantitating angiogenic patterns in a chick chorioallantoic membrane (CAM) system using a fractal analysis software program. The two delivery systems compared were sucrose acetate isobutyrate (SAIB) and calcium alginate. Initial HPLC laboratory tests confirmed that amiloride could be released from both SAIB and calcium alginate in vitro in a sustained manner for 72 h. The CAM studies confirmed that neither SAIB nor calcium alginate alone promoted or inhibited angiogenesis when compared to nontreated controls. The release of amiloride from each delivery vehicle resulted in a significant (P < 0.05) inhibition of angiogenesis following both 24 and 48 h of release compared to controls. There was no difference in inhibition of angiogenesis, however, when comparing SAIB + amiloride treated CAMs with calcium alginate + amiloride treated CAMs. These data suggest that both SAIB and calcium alginate may be useful delivery vehicles for the localized application of amiloride to control angiogenesis. Such a system could potentially control tumor angiogenesis without systemic effects.

Alginates↗
PubMed1999

[Epiphyseal injuries of the distal tibia. Does MRI provide useful additional information?].

Plain film radiography often underestimates the extent of injury in children with epiphyseal fracture. Especially Salter-Harris V fractures (crush fracture of the epiphyseal plate) are often primarily not detected. MRI of the ankle was performed in 10 children aged 9-17 (mean 14) years with suspected epiphyseal injury using 1.0-T Magnetom Expert. The fractures were classified according to the Salter-Harris-Rang-Odgen classification and compared with the results of plain radiography. In one case MRI could exclude epiphyseal injury; in four cases the MRI findings changed the therapeutic management. The visualisation of the fracture in three orthogonal planes and the possibility of detection of cartilage and ligamentous injury in MR imaging makes this method superior to conventional radiography and CT. With respect to radiation exposure MRI instead of CT should be used for the diagnosis of epiphyseal injuries in children.

Adolescent↗
PubMed1999

MRI findings in Hirayama's disease: flexion-induced cervical myelopathy or intrinsic motor neuron disease?

Hirayama's disease is a benign juvenile form of focal amyotrophy affecting the upper limbs. Previous studies have suggested that the disorder is a neck flexion induced cervical myelopathy. We report clinical and magnetic resonance imaging findings in nine patients with Hirayama's disease. Cervical imaging of seven patients revealed spinal cord changes consisting of focal atrophy and foci of signal alterations. On neck flexion a forward movement and mild reduction in the anteroposterior diameter of the lower cervical cord against the vertebral bodies was noted in affected individuals as well as in five normal controls. In contrast to earlier reports, none of our patients showed complete obliteration of the posterior subarachnoid space. Measurement of the anteroposterior spinal cord diameter in each vertebral segment (C4-C7) revealed no significant differences in the degree of spinal cord flattening between the two groups. Furthermore, two of our patients had significant degenerative changes in the cervical spine (disc herniation, retrospondylosis) contralateral to the clinically affected side. These degenerative changes resulted in a marked cord compression on neck flexion but were not associated with ipsilateral clinical abnormalities or spinal cord alterations. Our results argue against a flexion-induced cervical myelopathy and support the view that Hirayama's disease is an intrinsic motor neuron disease.

Adolescent↗
PubMed1999

Radiotherapy of unilateral choroidal metastasis: unilateral irradiation or bilateral irradiation for sterilization of suspected contralateral disease?

Radiotherapy is the highly effective standard in the treatment of choroidal metastasis. Visual acuity can be stabilized or increased in about 70-80% of eyes treated, thus prevailing the quality of life in these worse prognostic patients. In about 30-40% bilateral macroscopic disease is found at diagnosis. The best treatment for unilateral metastasis remains controversial: unilateral or bilateral irradiation for sterilization of suspected contralateral metastasis or unilateral irradiation without irradiation of the contralateral choroidea. In the analysis of a prospective study (ARO 95-08) 35 out of 50 patients with choroidal metastasis had unilateral disease and received unilateral irradiation with a lateral field using 6 MeV-photons (40 Gy in 20 fractions) without sparing the contralateral choroidea. Therefore the posterior contralateral choroidea received 50-70% of the total dose (20-28 Gy) for suspected micrometastasis. None of these patients developed contralateral choroidal metastasis during the median follow up time of 11.5 months. A unilateral field with 40 Gy for unilateral choroidal metastasis without sparing the contralateral choroidea seems to be effective in destroying contralateral micrometastasis with a lower risk of late side effects compared with bilateral fields.

Adult↗
PubMed1999

Catabolism of 2,7-dichloro- and 2,4,8-trichlorodibenzofuran by Sphingomonas sp strain RW1.

Due to their physicochemical and toxicological properties, polychlorinated dibenzofurans are regarded as a class of compounds providing reason for serious environmental concern. While the nonhalogenated basic structure dibenzofuran is effectively mineralized by appropriate bacterial strains, its polychlorinated derivatives are not. To elucidate the ability of the strain Sphingomonas sp RW1 to metabolize some of these chlorinated derivatives, we performed turnover experiments using 2,7-dichloro- and 2,4,8-trichlorodibenzofuran. As indicated by the oxygen-uptake rates determined for these two chlorinated dibenzofurans, Sphingomonassp RW1 can catabolize these chlorinated dibenzofurans yielding small quantities of oxidation products, which we isolated and subsequently characterized employing GC/MS and (1)H- as well as (13)C-NMR spectroscopy. In the case of 2,7-dichlorodibenzofuran, two metabolites accumulated, which we identified as 6-chloro- and 7-chloro-2-methyl-4H-chromen-4-one. The single metabolite isolated from the turnover experiments performed with 2,4,8-trichlorodibenzofuran was unequivocally identified as 6,8-dichloro-2-methyl-4H-chromen-4-one.

Journal Article↗
PubMed1999

Increased frequency of G-protein beta 3-subunit 825 T allele in dialyzed patients with type 2 diabetes.

BACKGROUND: A polymorphism (C825T) in exon 10 of the gene encoding the beta 3 subunit of heterotrimeric G proteins (GN beta 3) has recently been described, and the T allele was found to be associated with late-onset hypertension. Because hypertension is a known risk factor for the development of clinically manifest progressive renal disease, we examined the C825T polymorphism in older hemodialysis patients suffering from nondiabetic renal disease or type 2 diabetes with presumed diabetic nephropathy, respectively, and in older healthy controls. METHODS: Genotyping was performed by polymerase chain reaction, followed by restriction enzyme analysis. RESULTS: The study showed that the frequency of the T allele in the nondiabetic patients on dialysis (0.232) was significantly (P < 0.03) lower than in older healthy controls (0.293). In contrast, the frequency was significantly (P < 0.02) higher in older patients with type 2 diabetes on dialysis. No significant change in T-allele frequency was noted in older patients with type 2 diabetes without microangiopathy (0.286). The odds ratios for patients with type 2 diabetes on dialysis versus nondiabetic patients on dialysis were 3.24 (1.3 to 7.9, P < 0.00079) for TT/CC and 1.82 (1.07 to 3.09, P < 0.02) for CT/CC. The respective odds ratios for patients with type 2 diabetes on dialysis versus controls were 2.05 (1.07 to 3.9, P < 0.028) for CT/CC and 1.216 (0.79 to 1.87; P < 0.37) for CT/CC. CONCLUSION: The data do not support a role of the hypertension-associated T allele in the genesis of dialysis-dependent end-stage renal failure in general, but are compatible with a specific role of the T allele in the development or progression of diabetic nephropathy.

Aged↗