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B Schneider

Publications and source records attributed to B Schneider.

At least 127 records · Page 7Linked to original sources
PubMed2000

The methionine chain elongation pathway in the biosynthesis of glucosinolates in Eruca sativa (Brassicaceae).

Glucosinolates are nitrogen- and sulfur-containing plant natural products that have become increasingly important in human affairs as flavor precursors, cancer-prevention agents, and crop protectants. While many glucosinolates are biosynthesized from common amino acids, the major glucosinolates in economically important species of the Brassicaceae, such as Brassica napus (oilseed rape), are thought to be formed from chain-elongated derivatives of methionine or phenylalanine. We investigated the chain elongation pathway for methionine that is involved in glucosinolate biosynthesis in Eruca sativa. Isotopically labeled methionine and acetate were administered to cut leaves and the major product, 4-methylthiobutylglucosinolate (isolated as its desulfated derivative), was analyzed by MS and NMR. Administration of ¿U-(13)Cmethionine showed that the entire carbon skeleton of this amino acid, with the exception of the COOH carbon, is incorporated as a unit into 4MTB. Administration of ¿(13)C- and ¿(14)Căcetate gave a labeling pattern consistent with the operation of a three-step chain elongation cycle which begins with the condensation of acetyl-CoA with a 2-oxo acid derived from methionine and ends with an oxidative decarboxylation forming a new 2-oxo acid with one additional methylene group. Administration of ¿(15)Nmethionine provided evidence for the transfer of an amino group to the chain-elongated 2-oxo acid, forming an extended amino acid which serves as a substrate for the remaining steps of glucosinolate biosynthesis. The retention of a high level of (15)N in the products suggests that the amino transfer reactions and the chain elongation cycle are localized in the same subcellular compartment.

Acetates↗
PubMed2000

Role of immunological lymphocyte subset typing as a screening method for lymphoid malignancies in daily routine practice.

BACKGROUND: The major diagnostic role of peripheral lymphocyte subset typing is to distinguish between malignant and reactive conditions. METHODS: The present study evaluates the screening efficacy of flow cytometric lymphocyte subset typing for the presence of a lymphoid malignancy. Four hundred samples were analyzed with a combination of anti-T-, B-, and natural killer (NK)-cell monoclonal antibodies. RESULTS: Two hundred and twenty (55%) samples showed a normal distribution of lymphocyte subsets, 73 (18%) samples exhibited unspecific alterations of lymphocyte subsets, 19 (5%) samples exhibited a reactive phenotype typical of Epstein-Barr virus/cytomegalovirus (EBV/CMV) infection, and 88 (22%) samples expressed a phenotype suggestive of lymphoma. The most predictive independent factor of a lymphoma-specific phenotype was the absolute lymphocyte count (P = 0.0001, odds ratio 73.225). Seventy-eight percent of samples containing >/=4 x 10(9)/l lymphocytes and 2% of samples with lymphocyte counts <4 x 10(9)/l exhibited a lymphoma-specific phenotype. The specificity of the referring clinical comment was the second best predictor of a lymphoma-specific typing outcome (P = 0.0001, odds ratio 19.589). The independent predictive values of lymphocyte morphology and of relative lymphocyte counts were of borderline significance. CONCLUSIONS: The use of flow cytometric lymphocyte subset typing as a diagnostic screening method for lymphoma should be restricted to cases of unexplained elevation of absolute lymphocyte counts with or without morphological atypias and to cases with definite clinical symptoms of lymphoma.

Cytomegalovirus Infections↗
PubMed2000

[Comparison of manual lymph drainage with physical therapy in complex regional pain syndrome, type I. A comparative randomized controlled therapy study].

Sympathetic blockage and physiotherapy are among the most effective treatment approaches for the complex regional pain syndrome (CRPS). It is important to institute the treatment as early as possible in order to avoid major functional limitations of the affected limb. Unfortunately, there is a paucity of vigorously applied randomised or placebo-controlled trials for these therapeutic approaches. A prospective randomised study of 35 outpatient clinic patients with type I complex regional pain syndrome of the lower extremities lasting less than 6 months is described. One of two treatments, exercise alone or exercise in combination with manual lymph drainage, was applied for six weeks, three times a week, to the affected limb. Clinical and subjective parameters for pain, swelling, temperature, and range of motion were evaluated. Manual lymph drainage was chosen as adequate therapy for oedema reduction, whereas exercise was applied as standard therapy for contracture prophylaxis in reflex sympathetic dystrophy. Both groups were asked not to use analgesics but received extensive instructions for avoiding pain. Significant improvements in clinical parameters were observed in both groups, but no significant effect between treatment groups was found. Pain measurement alone with a verbal rating scale showed a tendency towards greater pain reduction in the group receiving lymph drainage. The results indicate that, during the first 6 months of complex regional pain syndrome type I, manual lymph drainage provides no additional benefit when applied in conjunction with an intensive exercise program.

Drainage↗
PubMed2000

The role of the Mg2+ cation in ATPsynthase studied by electron paramagnetic resonance using VO2+ and Mn2+ paramagnetic probes.

The electron paramagnetic resonance (EPR), electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation (HYSCORE) spectra of Mg2+-depleted chloroplast F1-ATPase substituted with stoichiometric VO2+ are reported. The ESEEM and HYSCORE spectra of the complex are dominated by the hyperfine and quadrupole interactions between the VO2+ paramagnet and two different nitrogen ligands with isotropic hyperfine couplings /A1/ = 4.11 MHz and /A2/ = 6.46 MHz and nuclear quadrupole couplings e2qQ1 approximately 3.89-4.49 MHz and e2qQ2 approximately 1.91-2.20 MHz, respectively. Aminoacid functional groups compatible with these magnetic couplings include a histidine imidazole, the epsilon-NH2 of a lysine residue, and the guanidinium group of an arginine. Consistent with this interpretation, very characteristic correlations are detected in the HYSCORE spectra between the 14N deltaM1 = 2 transitions in the negative quadrant, and also between some of the deltaM1 = 1 transitions in the positive quadrant. The interaction of the substrate and product ADP and ATP nucleotides with the enzyme has been studied in protein complexes where Mg2+ is substituted for Mn2+. Stoichiometric complexes of Mn x ADP and Mn x ATP with the whole enzyme show distinct and specific hyperfine couplings with the 31P atoms of the bonding phosphates in the HYSCORE (ADP, A(31Pbeta) = 5.20 MHz: ATP, A(31Pbeta) = 4.60 MHz and A(31Pgamma) = 5.90 MHz) demonstrating the role of the enzyme active site in positioning the di- or triphosphate chain of the nucleotide for efficient catalysis. When the complexes are formed with the isolated alpha or beta subunits of the enzyme, the HYSCORE spectra are substantially modified, suggesting that in these cases the nucleotide binding site is only partially structured.

Chloroplasts↗
PubMed2000

Partial pressure of ammonia versus ammonia in hepatic encephalopathy.

Ammonia is considered the major pathogenetic factor of cerebral dysfunction in hepatic failure. The correlation between total plasma ammonia and the severity of hepatic encephalopathy (HE), however, is variable. Because ammonia that is present in gaseous form readily enters the brain, the correlation with the grade of HE of the pH-dependent partial pressure of gaseous ammonia (pNH(3)) could be better than that of total arterial ammonia levels. To test this hypothesis, 56 cirrhotic patients with acute episodes of clinical HE (median age, 54 years; range, 21-75) were studied by clinical examination and by long-latency median-nerve sensory-evoked potentials (SEPs) N70 peak, an objective and sensitive electrophysiological measure of HE. pNH(3) was calculated from arterial blood according to published methods. The clinical grade of HE correlated (P <.001) with both pNH(3) and total ammonia, but correlation was stronger with pNH(3) (r =.79 vs.69, P =.01). A similar correlation was found for N70 peak latency (r =.71 with pNH(3) vs.64 with total ammonia, respectively, P =.08). In summary, arterial pNH(3) correlates more closely than total ammonia with the degree of clinical and electrophysiological abnormalities in HE. These findings support the ammonia hypothesis of HE and suggest that pNH(3) might be superior to total ammonia in the pathophysiological evaluation of HE.

Adult↗
PubMed2000

Axillary lymph nodes in breast cancer: is size related to metastatic involvement?

Usually when using imaging procedures, such as axillary mammography or ultrasonography, a cutoff level of 5 mm for lymph node size is postulated to be not only the limit of lymph node visibility but also a sign of metastatic involvement. The aim of this study was to evaluate whether this assumption, used as a basic hypothesis in many reports, is true. A series of 72 axillary specimens from 71 breast carcinoma patients operated at the university hospital of Vienna were analyzed. A comparison of histologically noninvolved axillary specimens with those showing metastatic involvement revealed that the two groups did not differ significantly according to the number or size of lymph nodes per axilla. For lymph nodes <5 mm the probability of being metastatically involved was still 10%. Enlarged lymph nodes (5-20 mm) had a slightly higher risk of being malignant (20%). In contrast, the probability of metastatic involvement for lymph nodes >20 mm was only 40%. We suggest that many reports dealing with the prediction of malignancy in axillary lymph nodes may have used misleading basic assumptions, so the results of these studies must be viewed critically.

Axilla↗
PubMed2000

Effect of interleukin-3, stem cell factor and granulocyte-macrophage colony-stimulating factor on committed stem cells, long-term culture initiating cells and bone marrow stroma in a one-step long-term bone marrow culture.

Long-term bone marrow culture (LTBMC) supports both differentiation and conservation of hematopoietic progenitor cells. During the culture period, the frequency and proliferative potential of early repopulating stem cells that give rise to progenitors detectable after 5 weeks in LTBMC--so-called long-term culture-initiating cells (LTC-IC)--can be investigated. The adherent stroma cell layer was modified by interleukin-3 (IL-3) + granulocyte-macrophage colony-stimulating factor (GM-CSF)+ stem-cell factor (SCF) with an increased cellularity and higher percentage of differentiated myeloid cells and a reduced percentage of stroma cells. We have studied the effects of stimulative cytokines, such as GM-CSF, SCF, and IL-3, on proliferation of committed colony-forming unit cells (CFU-C), LTC-IC, and stroma cell formation in LTBMC of unseparated bone-marrow cells. IL-3, GM-CSF, and SCF significantly stimulated the cumulative proliferation of nucleated cells and committed CFU-C. Weekly stimulation of LTBMC during the culture period did not exhaust the proliferative capacity of stem cells as seen in maintenance of LTC-IC after 5 weeks in LTBMC. In contrast, no LTC-IC were seen in limiting dilution analyses from LTBMC cultured 5 weeks without cytokine supplementation. Our data indicate that an increased proliferation of committed stem cells can be achieved by the addition of stimulatory growth factors, and maintenance of LTC-IC is possible over a period of 5 weeks. A net expansion of LTC-IC if compared with the starting bone-marrow suspension could not be obtained after a 5-week LTBMC period.

Bone Marrow↗
PubMed2000

Comparison of immersion ultrasound biometry and partial coherence interferometry for intraocular lens calculation according to Haigis.

BACKGROUND: The precision of intraocular lens (IOL) calculation is essentially determined by the accuracy of the measurement of axial length. In addition to classical ultrasound biometry, partial coherence interferometry serves as a new optical method for axial length determination. A functional prototype from Carl Zeiss Jena implementing this principle was compared with immersion ultrasound biometry in our laboratory. PATIENTS AND METHODS: In 108 patients attending the biometry laboratory for planning of cataract surgery, axial lengths were additionally measured optically. Whereas surgical decisions were based on ultrasound data, we used postoperative refraction measurements to calculate retrospectively what results would have been obtained if optical axial length data had been used for IOL calculation. For the translation of optical to geometrical lengths, five different conversion formulas were used, among them the relation which is built into the Zeiss IOL-Master. IOL calculation was carried out according to Haigis with and without optimization of constants. RESULTS: On the basis of ultrasound immersion data from our Grieshaber Biometric System (GBS), postoperative refraction after implantation of a Rayner IOL type 755 U was predicted correctly within +/- 1 D in 85.7% and within +/- 2 D in 99% of all cases. An analogous result was achieved with optical axial length data after suitable transformation of optical path lengths into geometrical distances. CONCLUSIONS: Partial coherence interferometry is a noncontact, user- and patient-friendly method for axial length determination and IOL planning with an accuracy comparable to that of high-precision immersion ultrasound.

Adult↗
PubMed2000

Postischemic cardiac function recovery in the isolated rat heart: effects of adenosine deaminase and nucleoside transport inhibition.

BACKGROUND AND AIMS: This study assessed the cardioprotective effects of inhibitors of adenosine metabolism in an isolated perfused rat heart model. Specifically, we studied the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)-adenine and the selective nucleoside transport inhibitor S-(p-nitrobenzyl)-6-thioinosine, in terms of their potential to enhance protection when added to Bretschneider's cardioplegic solution. METHODS: Rat hearts were infused for 5 min with Krebs-Henseleit buffer solution (group 1), Bretschneider's cardioplegic solution (group 2), Bretschneider's cardioplegic solution with the addition of 25 microM erythro-9-(2-hydroxy-3-nonyl)-adenine and 5 microM S-(p-nitrobenzyl)-6-thioinosine (group 3), and Bretschneider's cardioplegic solution with the addtion of 25 microM erythro-9-(2-hydroxy-3-nonyl)-adenine only (group 4). After cardioplegic arrest and 45 min of ischemic storage at 25 degrees C, the functional recovery of the hearts was tested during 15 min of Langendorff reperfusion and then 45 min of working heart reperfusion. RESULTS: In relation to the cardioprotective effects of Bretschneider's cardioplegic solution alone, we observed an improved recovery of hemodynamic function of the hearts with the addition of both erythro-9-(2-hydroxy-3-nonyl)-adenine and S-(p-nitrobenzyl)-6-thioinosine. However, the myocardial adenosine triphosphate (ATP) concentration remained unchanged. Bradycardia observed under the addition of erythro-9-(2-hydroxy-3-nonyl)-adenine alone was prevented by the addition of S-(p-nitrobenzyl)-6-thioinosine. CONCLUSION: A combination of both substances may be tested further for cardiac preservation, as it might improve the recovery from ischemia at moderate temperatures.

Adenine↗
PubMed2000

Defining the role of stereotactic radiosurgery versus microsurgery in the treatment of single brain metastases.

Stereotactic radiosurgery (RS) and surgery have proved to be effective treatment modalities for brain metastasis. We followed 133 patients whose treatment for intracranial disease was either RS or a single surgical resection at the University of Vienna from August 1992 through October 1996. All patients who received additional Whole Brain Radiotherapy were included. This was a retrospective, case-control study comparing these treatment modalities. Sixty-seven patients were treated by RS and 66 patients were treated by microsurgery. The median size of the treated lesions for RS patients was 7800 mm3, and 12500 mm3 for microsurgery patients, respectively. The median dose delivered to the tumour margin for RS patients was 17 gray. The median survival for patients after RS was 12 months, and 9 months for patients after microsurgery. This difference was not statistically significant (p = 0.19). Comparison of local tumour control, defined as absence of regrowth of a treated lesion, showed that tumours following RS had a preferred local control rate (p < 0.05). Univariate and multivariate analysis showed that this fact was due to a greater response rate of "radioresistant" metastasis to RS (p < 0.005). Postradiosurgical complications included the onset of peritumoural oedema (n = 5) and radiation necrosis (n = 1). Two patients after microsurgery experienced local wound infection. One postoperative death occurred due to pulmonary embolism in this group. On the basis of our data we conclude that RS and microsurgery combined with Whole Brain Radiotherapy are comparable modalities in treating single brain metastasis. Concerning morbidity and local tumour control, in particular in cases of "radioresistant" primary tumours, RS is superior. Therefore we advocate RS except for cases of large tumours (> 3 cm in maximum diameter) and for those with mass effect.

Brain Neoplasms↗
PubMed2000

Vitamin D in schizophrenia, major depression and alcoholism.

25-Hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, calcium, phosphate and parathyreoidal hormone levels were assessed in 34 patients with schizophrenia (DSM-III-R, 44% female, mean age 38.9 +/- 2.1 years), 30 patients with alcohol addiction (16% female, mean age 48.7 +/- 2.2 years), 25 patients with major depression (56% female, mean age 57.6+/- years) and 31 healthy controls. Only 25-hydroxyvitamin D3 and 1,25-dihydroxvitamin D3 levels were significantly lower in all groups of psychiatric patients than in normal controls, but not phosphate, calcium and parathyreoidal hormone levels. Significant differences in the vitamin D levels could not be found between the three psychiatric groups. These findings do not support the idea that vitamin D is specifically involved in the pathophysiology of depression. The difference in patients as compared to the healthy controls might be related to a different social background resulting in differing habits e.g. of nutrition.

Adult↗
PubMed2000

Variability of phenylpropanoid precursors in the biosynthesis of phenylphenalenones in Anigozanthos preissii.

Feeding experiments using 13C labelled precursors and NMR spectroscopic studies revealed general biosynthetic incorporation of phenylalanine and variable incorporation of cinnamic acid, p-coumaric acid, caffeic acid and ferulic acid into phenylphenalenones in root cultures of Anigozanthos preissii. Evidence was obtained for parallel pathways of phenylphenalenone biosynthesis, with respect to the left phenylpropanoid unit, and a sequence involving utilisation of p-coumaric acid with late generation of an intermediate catechol moiety in the right phenylpropanoid unit.

Magnetic Resonance Spectroscopy↗
PubMed2000

Effects of estradiol and estradiol sulfamate on the uterus of ovariectomized or ovariectomized and hypophysectomized rats.

Estradiol sulfamate (J995), estradiol-17beta with a substituted sulfamate group in position 3, has much higher systemic estrogenic activity after oral administration than 17beta-estradiol (E2) due to reduced hepatic metabolism of the drug. The lower dose necessary for achievement of adequate systemic estrogenic effects results in a substantial reduction of otherwise commonly observed hepatic side-effects. This makes J995 a strong candidate as an estrogen suitable for oral administration. The present study was performed to examine and compare the effects of J995 and E2 on the uterus after oral or subcutaneous administration to ovariectomized or ovariectomized+hypophysectomized female rats, in particular on the levels of the estrogen receptor (ER) (alpha+beta), ERalpha mRNA and insulin-like growth factor-I (IGF-I) mRNA. The ER levels were determined using a ligand binding assay and the mRNA levels using solution hybridization. The doses of J995 or E2 were chosen to achieve comparable uterotrophic activity. The rats were treated with hormones for 7 days and the treatment was initiated 14 days after surgery. We conclude that there are no major differences in the uterine response to treatment with J995 or E2 with respect to the effects on ER and ERalpha mRNA levels. The IGF-I mRNA level though, is more affected by J995 than by E2 after 7 days of treatment, indicating a prolonged effect of J995.

Administration, Oral↗
PubMed2000

Phenalenones from Strelitzia reginae.

Phytochemical analysis of rhizomes of Strelitzia reginae resulted in the isolation and identification of an unusual new (1) and four known phenalenone-type compounds, which were identified using MS and NMR spectroscopic techniques. The occurrence of phenalenones in Strelitziaceae, which has been established for the first time, is of chemotaxonomic interest.

Magnetic Resonance Spectroscopy↗
PubMed2000

Role of nucleoside diphosphate kinase in the activation of anti-HIV nucleoside analogs.

Nucleoside analogs are currently used in antiretrovirus therapies. The best known example is AZT one of the first drug to be used for the treatment of AIDS. However, only the triphosphate derivatives of these compounds act as substrates of the viral reverse transcriptase. Since they do not enter cells, nucleoside analogs are administered and phosphorylated by cellular kinases. The last step in this phosphorylation pathway is catalyzed by nucleoside diphosphate (NDP) kinase. The incorporation of the nucleoside triphosphates into nascent viral DNA chain results in termination of the elongation process. We have performed kinetics studies of the phosphorylation reaction by NDP kinase of dideoxynucleoside diphosphates such as 2',3'-dideoxy-3'-azidothymidine diphosphate (AZT-DP) and 2',3'-dideoxy-2',3'-didehydrothymidine diphosphate (d4T-DP). We show that the catalytic efficiency is strongly decreased and, therefore, that the reaction step catalyzed by NDP kinase constitutes a bottleneck in the processing pathway of anti-HIV compounds. In addition, the affinity of the analogs in the absence of catalysis was determined using a catalytically inactive NDP kinase mutant, showing a reduction of affinity by a factor of 2 to 30, depending on the analog. The structure of NDP kinase provides a structural explanation for these results. Indeed, all nucleoside analogs acting as chain terminators must lack a 3'-OH in the nucleotide deoxyribose. Unfortunately, this same substitution is detrimental for their capacity to be phosphorylated by NDP kinase. This defines the framework for the design of new nucleoside analogs with increased efficiency in antiretroviral therapies.

Anti-HIV Agents↗
PubMed2000

Formulation development and antitumor activity of a filter-sterilizable emulsion of paclitaxel.

PURPOSE: Paclitaxel is currently administered i.v. as a slow infusion of a solution of the drug in an ethanol:surfactant:saline admixture. However, poor solubilization and toxicity are associated with this drug therapy. Alternative drug delivery systems, including parenteral emulsions, are under development in recent years to reduce drug toxicity, improve efficacy and eliminate premedication. METHODS: Paclitaxel emulsions were prepared by high-shear homogenization. The particle size of the emulsions was measured by dynamic light scattering. Drug concentration was quantified by HPLC and in vitro drug release was monitored by membrane dialysis. The physical stability of emulsions was monitored by particle size changes in both the mean droplet diameter and 99% cumulative distribution. Paclitaxel potency and changes in the concentration of known degradants were used as chemical stability indicators. Single dose acute toxicity studies were conducted in healthy mice and efficacy studies in B 16 melanoma tumor-bearing mice. RESULTS: QW8184, a physically and chemically stable sub-micron oil-in-water (o/w) emulsion of paclitaxel, can be prepared at high drug loading (8-10 mg/mL) having a mean droplet diameter of <100 nm and 99% cumulative particle size distribution of <200 nm. In vitro release studies demonstrated low and sustained drug release both in the presence and absence of human serum albumin. Based on single dose acute toxicity studies, QW8184 is well tolerated both in mice and rats with about a 3-fold increase in the maximum-tolerated-dose (MTD) over the current marketed drug formulation. Using the B16 mouse melanoma model, a significant improvement in drug efficacy was observed with QW8184 over Taxol. CONCLUSIONS: QW8184, a stable sub-micron o/w emulsion of paclitaxel has been developed that can be filter-sterilized and administered i.v. as a bolus dose. When compared to Taxol, this emulsion exhibited reduced toxicity and improved efficacy most likely due to the composition and dependent physicochemical characteristics of the emulsion.

Animals↗
PubMed2000

Relative hypoleptinemia in patients with type 1 and type 2 diabetes mellitus.

OBJECTIVE: To determine the relation between plasma leptin concentrations and metabolic control in human diabetes mellitus. DESIGN AND SUBJECTS: Cross sectional study consisting of 156 patients with diabetes mellitus type 1 (n=42), type 2 (n=114), and non-diabetic subjects (n=74). RESULTS: Plasma leptin concentrations were lower (P<0.05) in type 1 (8.3+/-1.7 ng/ml) and type 2 diabetic (14.9+/-1.8 ng/ml) than in non-diabetic humans (18.3+/-1.9 ng/ml). Only female type 1 and type 2 diabetic subjects also had decreased leptin/BMI ratios (P<0.05 vs non-diabetic females). The log rank test identified age-adjusted correlation of plasma leptin concentration with sex (P<0.0004) and body mass index (P<0.0218), but not with glycosylated haemoglobin A1c (P>0.5) in all groups. Plasma leptin was correlated with age (P<0.0058) and serum triglycerides (P<0.0199) in type 1 diabetic patients, and with serum cholesterol (P<0.0059) and LDL (P<0.0013) in type 2 diabetic patients. CONCLUSIONS: Defective leptin production and/or secretion might be present independently of metabolic control in female patients with type 1 or type 2 diabetes mellitus.

Adult↗