Search PubMed⌕ Search

Biomedical subjects

B Schneider

Publications and source records attributed to B Schneider.

At least 91 records · Page 5Linked to original sources
PubMed2001

3Beta-brassinosteroid dehydrogenase activity in Arabidopsis and tomato.

Enzymatic conversion of 24-epiteasterone to 3-dehydro-24-epiteasterone, representing a reversible step in the biosynthesis of 24R-methyl brassinosteroids, was monitored in vitro in Arabidopsis thaliana and Lycopersicon esculentum using fluorescent tagging and HPLC analysis. In both species 24-epiteasterone was metabolized by the cytosolic fraction of induced root-callus suspension cultures in a NAD dependent manner. This 3beta-dehydrogenation was only slightly inhibited by 12-fold excess of other 3beta-hydroxy intermediates of the early (cathasterone) and late C-6 oxidation pathway (6-deoxo-cathasterone, 6-deoxo-teasterone), indicating a rather specific protein. 3-Dehydro-6-deoxoteasterone and 3alpha-hydroxy intermediates of brassinosteroid biosynthesis did not reduce conversion of 24-epiteasterone to 3-dehydro-24-epiteasterone. In contrast to light-grown cultures the reaction was clearly inhibited in the dark.

Alcohol Oxidoreductases↗
PubMed2001

AC133 expression on acute myeloid leukemia blasts: correlation to FAB and to CD34 expression and possible implications for peripheral blood progenitor cell purging in AML.

AC133 is an antigen expressed on CD34+ hematopoietic progenitor cells. In acute myeloid leukemia (AML) it is expressed on leukemic blasts of most FAB subtypes. However, few data are available regarding coexpression of other surface antigens. We measured AC133 expression on AML blasts from 28 consecutive patients at initial diagnosis (n=26) or at diagnosis of first relapse (n=2) and on 26 leukapheresis products from 14 patients. In AML AC133 correlated with CD34 expression (Spearman r=0.4711, P=0.0114) and even stronger with combined CD34/CD33 expression (Spearman r=0.5083, P=0.0068). In leukapheresis products AC133 expression correlated with CD34 expression (Spearman r=0.7495, P=0.002) and the yield of the obtained amount of CD34+ cells (Spearman r=0.6484, P=0.0121). In conclusion AC133 expression is closely related to CD34 expression in AML. In leukapheresis products AC133 provides an additional marker for selection of PBPC autografts in AC133- AML.

AC133 Antigen↗
PubMed2001

Mortality in affective disorders.

BACKGROUND: To investigate the mortality rates in affective disorders due to unnatural and natural causes with respect to illness subtype and social-demographic features. METHODS: Mortality data were determined from a prospective study of 354 outpatients with affective disorders during a follow-up period of 5 years. Death from natural and unnatural causes was compared to sex- and age-specific expectations in the general population. Standardized mortality rates (SMR) in diagnostic subgroups and the influence of social-demographic features were investigated. RESULTS: The observed 30 deaths represented nearly three times (SMR, 2.9) the number expected on the basis of age- and sex-standardized reference population rates. Death from natural causes occurred with the same rate as expected (SMR, 1.0), death from unnatural causes was 28.8 times higher than expected. Women with affective disorders had a considerable high risk to die from unnatural causes (SMR, 47.1). A significant excess of unnatural death was found in all subtypes of affective disorders, particularly in recurrent major depressive episodes (SMR, 46.7). LIMITATIONS: The sample was restricted in size. Therefore subgroup differences and multiple relationships of risk factors could not be analyzed with high statistical power. CONCLUSIONS: The results corroborate earlier findings of excess mortality in major affective disorders and strengthen the view that suffering from recurrent major depression confers per se an important biological risk for suicide. Natural causes of death in affective disorders are comparable to expectations from reference populations. Social-demographic characteristics may contribute to an additional risk of premature death by suicide, particularly in women.

Accidents↗
PubMed2001

NDP kinase reactivity towards 3TC nucleotides.

Nucleoside diphosphate (NDP) kinase is usually considered as the enzyme responsible for the last step of the cellular phosphorylation pathway leading to the synthesis of biologically active triphospho-derivatives of nucleoside analogs used in antiviral therapies and in particular in the treatment of AIDS. NDP kinase lacks specificity for the nucleobase and can use as substrate both ribo- or 2'-deoxyribonucleotides. However, only nucleoside analogs with a sugar moiety in the D-configuration (e.g. 3'-deoxy-3'-azidothymidine (AZT), 2',3'-didehydro-2',3'-dideoxythymidine (d4T)) have so far been analyzed as substrates of NDP kinase. In contrast, beta-L-2',3'-dideoxy-3'-thiacytidine (3TC), also called lamivudine, is a nucleoside analog that is now widely used in AIDS therapy and has a sugar moiety in the L-configuration. Using protein fluorescence to monitor the phosphotransfer between the enzyme and the nucleotide derivative at the presteady state, we have studied the reactivity of 3TC triphosphate and of other L-dideoxynucleotides with NDP kinase. We found that L-dideoxynucleoside triphosphates have a poor affinity for NDP kinase and that the catalytic efficiency of the phosphorylation of L-dideoxyderivatives is very low as compared with their D-enantiomers. We discuss these results using a computer model of 3TC diphosphate bound to the NDP kinase active site. NDP kinase may not seem to be the major enzyme phosphorylating 3TC-DP, in contrast to current opinion.

Animals↗
PubMed2001

Psychopathological predictors of suicide in patients with major depression during a 5-year follow-up.

OBJECTIVE: It is widely known that the risk of suicide is higher in cases of major depressive disorders in comparison to the general population. The purpose of this study was to examine which psychopathologic symptoms during the index episode are predictors for an increased risk of suicide in the further course of major depression. METHOD: Mortality data were determined from a prospective study of 280 patients with major depression (DSM-III-R, single episode or recurrent) during a follow-up period of 5 years. The predictive power of different depressive symptoms including psychotic symptoms for suicide risk was investigated. RESULTS: Patients who committed suicide (N = 16) during the follow-up period had reported significantly more often hypochondriacal preoccupations or delusions (but not delusions or preoccupations of impoverishment, guilt or sin), suicidal thoughts and suicide attempts as well as feelings of severe hopelessness during the index episode than still living patients or patients who had died from natural causes. CONCLUSION: These symptoms seem to be helpful early predictors for the risk of suicide during the further course of illness. This should be taken into account for suicide prevention in the course of major depression.

Adolescent↗
PubMed2001

Impact of the factor II: G20210A variant on the risk of venous thromboembolism in relatives from families with the factor V: R506Q mutation.

OBJECTIVES: Factor V: R506Q mutation and the prothrombin G20210A variant (factor II: G20210A variant) are associated with an increased risk of venous thromboembolism (VTE). In cohorts of unrelated patients a cosegregation of both mutations has been shown to be associated with an increased risk of developing VTE. The aim of this study was to investigate the impact of the coinheritance of both mutations on the risk of VTE in relatives of symptomatic carriers of the factor V: R506Q mutation and the factor II: G20210A variant. PATIENTS AND METHODS: Four families with 48 family members were investigated for the presence of the factor V: R506Q mutation and the factor II: G20210A mutation, and their clinical history was evaluated. RESULTS: VTE was more frequent in family members with a combined defect (3/10; 30%) compared to those with a single mutation (1/16; 6%) or without a defect (1/12; 8%). The probability for VTE for 40-yr-old individuals with both mutations, a single mutation and no mutation was 56%, 12% and 20%, respectively. CONCLUSIONS: These data suggest that the G to A transition at position 20210 of the prothrombin gene leads to an increase in the risk of VTE in carriers of the factor V: R506Q mutation. The determination of the factor II: G20210A variant in index patients carrying a factor V: R506Q mutation and, if present, in family members may help to identify individuals who are at high risk for VTE.

Adolescent↗
PubMed2001

Monocular unmasking of noise-embedded patterns.

Binocular disparity cues may help an observer "unmask" a target in a background, thereby enhancing its detectability (e.g., Moraglia & Schneider, 1992). Here, we sought to determine whether similar effects could be produced by monocular displacement cues resulting from a two-frame sequential presentation of a Gabor pattern (a sinusoidal modulation of luminance combined with a Gaussian modulation of local contrast) embedded in an unvarying field of two-dimensional Gaussian noise. The Gabor in the second frame was spatially displaced relative to its location in the first frame; the horizontal displacement corresponded to a phase shift of the peak spatial frequency of the Gabor of 0 degree, 90 degrees, 180 degrees, 360 degrees, or 540 degrees. Monocular detection thresholds for the Gabor were appreciably lower for the 90 degrees, 180 degrees, and 540 degrees shift, than for the 0 degree and 360 degrees values. We explain these findings in terms of a model that constitutes the monocular analog of our summation model of binocular unmasking.

Adult↗
PubMed2001

Deregulated expression of prostate apoptosis response gene-4 in less differentiated lymphocytes and inverse expressional patterns of par-4 and bcl-2 in acute lymphocytic leukemia.

INTRODUCTION: Prostate apoptosis response gene-4, known as par-4, is a new proapoptotic factor functionally required but not sufficient for apoptosis. Since there is evidence from prostate cancer cells that par-4 is involved in regulation of bcl-2 we assessed expression of par-4 and bcl-2 in different populations of normal and neoplastic lymphocytes. MATERIALS AND METHODS: Expression of par-4 mRNA and protein in different subpopulations of normal and neoplastic lymphocytes was assessed by reverse transcription polymerase chain reaction and Western blot. RESULTS: Par-4 mRNA was not detectable in lymphocytes of healthy volunteers (n = 10), but was present in the majority of samples of chronic lymphocytic leukemia (n = 30), chronic lymphocytic leukemia/prolymphocytic leukemia (n = 6) and acute lymphocytic leukemia (n = 10). Par-4 protein was expressed unanimously in samples of mononuclear cells from healthy volunteers and patients with CLL, but less frequently in immature lymphocytes, including neoplastic cells of CLL/PLL and ALL. The decreased frequency of par-4 expression in immature subpopulations was confirmed by results on lymphocytic cell lines at various stages of maturation. Comparing the expressional patterns of par-4 and bcl-2 there was an inverse relationship of both proteins in ALL and different lymphocytic cell lines, indicating a functional relationship of par-4 and bcl-2. CONCLUSIONS: This study establishes par-4 as a factor expressed in the majority of normal and neoplastic lymphocytic cells, demonstrating a decreased frequency of protein expression in less differentiated lymphocytes and an inverse expressional pattern of par-4 and bcl-2 in lymphocytic cell lines and ALL.

Apoptosis Regulatory Proteins↗
PubMed2001

T-large granular lymphocyte leukaemia with natural killer cell-like cytotoxicity and expression of two different alpha- and beta-T-cell receptor chains.

We describe a case of cytotoxic T-large granular lymphocyte leukaemia showing typical morphological features, expressing antigens characteristic for cytotoxic T cells and exhibiting marked natural killer-like cytotoxicity towards different target cells. Moreover, characterization of the T-cell receptors revealed simultaneous expression of two different types of beta-chains as well as alpha-chains by the malignant cell clone. The patient had an 8 year history of indolent disease, before progressing to an aggressive clinical course hardly responsive to chemotherapeutic treatment. This is the first description of a peripheral T-cell neoplasm expressing four distinct types of T-cell receptor molecules.

Disease Progression↗
PubMed2001

Mechanism of phosphoryl transfer by nucleoside diphosphate kinase pH dependence and role of the active site Lys16 and Tyr56 residues.

Nucleoside diphosphate (NDP) kinase phosphorylates nucleoside diphosphates with little specificity for the base and the sugar. Although nucleotide analogues used in antiviral therapies are also metabolized to their triphosphate form by NDP kinase, their lack of the 3'-hydroxyl of the ribose, which allows them to be DNA chain terminators, severely impairs the catalytic efficiency of NDP kinase. We have analyzed the kinetics parameters of several mutant NDP kinases modified on residues (Lys16, Tyr56, Asn119) interacting with the gamma-phosphate and/or the 3'-OH of the Mg2+-ATP substrate. We compared the relative contributions of the active-site residues and the substrate 3'-OH for point mutations on Lys16, Tyr56 and Asn119. Analysis of additional data from pH profiles identify the ionization state of these residues in the enzyme active form. X-ray structure of K16A mutant NDP kinase shows no detectable rearrangement of the residues of the active site.

Adenosine Triphosphate↗
PubMed2001

[The role of dobutamine stress echocardiography in the clinical routine of a department of cardiology].

BACKGROUND: The aim of this study was to assess the role of dobutamine stress echocardiography (SE) for diagnosis and therapy of coronary artery disease (CAD) in the routine practice of a cardiological department in which bicycle stress-testing, scintigraphy and coronary angiography are available. METHODS: Between January 1997 and September 1998, 123 patients (79 men, 44 women, 60.1 +/- 9.9 years) underwent SE. SE-indication, SE-result and the consequence of the SE were registered. A telephone follow-up, asking for events and cardiac interventions, took place after at least one year. RESULTS: SE was performed in 57 patients with suspected CAD and in 66 patients with known CAD. The indications were inconclusive bicycle stress-testing or perfusion scintigrams (n = 77), search for hibernation (n = 22), discrepancy between presenting symptoms and results of previous investigations (n = 14) and preoperative risk stratification (n = 10). In the group with suspected CAD, the proportion of female patients was higher (p = 0.001), in the group with known CAD the proportion of male patients was higher (p = 0.002). SE showed an ischemic reaction in 35 patients, hibernation in 24 patients, no ischemic reaction in 56 patients and was inconclusive in 8 patients. The consequence of SE was recommendation for diagnostic coronary angiography (n = 27), revascularisation (n = 10), abstention from any invasive intervention (n = 77), noncardiac surgery (n = 9) and electrophysiological investigation (n = 1). During the investigated period, 955 bicycle stress-tests, 677 Thallium scintigrams and 987 coronary angiograms were carried out. During the follow-up (15 +/- 2.9 months) 4 patients died. In 6 patients cardiac interventions were carried out. No differences were observed regarding events and interventions depending on SE results and consequences. CONCLUSIONS: At a cardiological department SE plays a role if findings are inconclusive and if hibernation or operative risk is looked for. A negative SE result most commonly leads to abstention from invasive intervention. If the SE result is positive, the recommendation for invasive intervention is also influenced by the clinical symptoms and the size of the ischemically reacting myocardium.

Adrenergic beta-Agonists↗
PubMed2001

A preceding exchange with polyglucose versus glucose solution modifies peritoneal equilibration test results.

The peritoneal equilibration test (PET) is an important tool for evaluating peritoneal membrane characteristics. The polyglucose icodextrin induces ultrafiltration caused by colloid osmosis through the small pores of the peritoneal membrane and therefore is especially effective during long dwell times. The main indications for polyglucose solutions are daytime dwells in patients on automated peritoneal dialysis and nighttime exchanges in continuous ambulatory peritoneal dialysis (CAPD) patients. In CAPD patients, PET is started immediately after the icodextrin exchange. Therefore, we performed two PETs in each of 15 CAPD patients. PET post-1.36% glucose was performed immediately after a preceding exchange with 2 L of 1.36% glucose dialysate solution (dwell time, 10 hours). PET postpolyglucose was started immediately after a preceding exchange with 2 L of 7.5% icodextrin solution (dwell time, 10 hours). The dialysate to plasma (D/P) ratio of creatinine, phosphate, and sodium during PET postpolyglucose was significantly greater than during PET post-1.36% glucose at 1, 2, 3, and 4 hours of dwell time. The quotient of dialysate glucose at 1, 2, and 4 hours of dwell time to dialysate glucose at 0 dwell time was significantly lower in PET postpolyglucose compared with PET post-1.36% glucose. In the case of creatinine, phosphate, and glucose, PET postpolyglucose curves tended to be steeper than those of PET post-1.36% glucose during the first hour of dwell time, whereas both curves were parallel between 1 and 4 hours of dwell time. The course of D/P ratio curves of urea nitrogen, protein, and albumin was nearly identical between PET postpolyglucose and PET post-1.36% glucose. In a subgroup of 5 patients, D/P ratios of creatinine and phosphate were also greater in PET postpolyglucose compared with PET performed after a long dwell with 2.27% glucose solution. Before a scheduled PET, CAPD patients using icodextrin solution during the nighttime should perform their nighttime exchange with conventional glucose solution.

Adult↗
PubMed2001

Prevention of venous thromboembolism after knee arthroscopy with low-molecular weight heparin (reviparin): Results of a randomized controlled trial.

PURPOSE: Deep venous thrombosis (DVT) is a common, important complication of major orthopaedic surgery, particularly knee arthroplasty. Knee arthroscopy is increasingly performed on an outpatient basis. Few reports have elucidated the incidence of venous thromboembolism (VTE) in patients undergoing arthroscopic surgery receiving no prophylaxis. The objective of the present trial was to evaluate the risk of VTE in those patients and to determine efficacy and safety of a low-molecular weight heparin (LMWH) in preventing VTE. TYPE OF STUDY: This is the first controlled randomized trial using objective diagnostic methods with blinded outcome assessment to reveal the incidence of VTE in outpatient arthroscopy and determine efficacy and safety of a LMWH (reviparin sodium) in preventing VTE in these patients. METHODS: There were 262 patients undergoing elective knee arthroscopy prospectively randomized to receive either no treatment or reviparin once daily subcutaneously for 7 to 10 days. The blindly assessed primary outcome measure was the incidence of DVT detected by compression color-coded sonography. Both groups were comparable with regard to demographics and baseline characteristics. RESULTS: 239 patients were evaluable (122 no treatment, 117 receiving LMWH). 6 DVT were detected - 5 in the control group (5/117 - 4.1%) and only one in the active treatment group (1/116 - 0.85%). This particular patient had a low level of protein C and a subnormal level of protein S. The odds ratio of 4.95 approximates a relative risk reduction of about 80%. Treatment with reviparin was safe and well tolerated. There was no major bleeding, four patients with minor bleedings. One patient had a transitory fall in platelet count below 100 giga-particles/L without any clinical symptoms. CONCLUSIONS: Patients undergoing knee arthroscopy have a moderate risk of VTE and effective prophylaxis can be achieved with LMWH (reviparin).

Adult↗
PubMed2001

Double-blind randomised placebo-controlled phase III study of an E. coli extract plus 5-fluorouracil versus 5-fluorouracil in patients with advanced colorectal cancer.

The primary aim of this study was to evaluate the toxicity (mucositis, diarrhea and leucopenia) of a therapy with 5-fluorouracil (CAS 51-21-8; 5-FU) plus an E. coli extract (LC-Extract, Laves coli extract, Colibiogen inject, cell-free soluble fraction from lysed E. coli, Laves strain) in comparison with 5-FU plus placebo. Secondary endpoints included general toxicity, response rate according to WHO, survival time and quality of life. 164 patients with advanced colorectal cancer were enrolled in this randomised, placebo-controlled, double-blind, multicenter phase III study. The treatment consisted of 0.167 ml/kg/d LC-Extract or placebo followed by 500-750 mg/m2/d 5-FU on five consecutive days, repeated every three weeks for up to six treatment cycles. 158 (77 verum, 81 placebo) patients were evaluable for toxicity, 144 (72 verum, 72 placebo) evaluable for response. The therapy with LC-Extract was well tolerated. Adverse events that occurred during the study were mainly judged as 5-FU- or tumor-related. Toxicity from treatment with 600 mg/m2/d 5-FU in both treatment groups was very low. After treatment with 750 mg/m2/d 5-FU patients in the placebo-group experienced a higher CTC toxicity than in the LC-Extract groups. Remission rate and survival time showed a slight trend in favour of LC-Extract. These results suggest a positive benefit-risk ratio of the additional application of LC-Extract to 5-FU in the treatment of advanced colorectal cancer especially for administration of high doses of 5-FU.

Adolescent↗
PubMed2001

[Dementia and suicide].

The relationship between suicide and dementia has not systematically been investigated, although the prevalence of both, dementia and suicide, increases with age. In contrast to patients with other psychiatric disorders, patients with dementia were not found to die from suicide more often than expected (SMR, 0). Thus the diagnosis of dementia does not contribute to the elevated suicide risk in old age. In studies using the psychological autopsy method, dementia was rarely diagnosed in suicide victims. Suicide attempts were observed in less than 1% of all patients with dementia. Depression as an important common risk factor of suicide and dementia is often found in patients with Alzheimer's disease (0% to 86%) as well as in patients with multi-infarct dementia (20% to 45%). However major depression was found significantly more often in vascular dementia than in dementia of Alzheimer type. Suicidal thoughts and intents, wishes to die and feelings that life is not worth living were reported in 1% to 42% of all patients with dementia, especially if these patients also suffered from depression. This review comprehensively presents the association between cognitive deficits, insight in early stages of dementia and suicidality and possible confounders which have not systematically been investigated up to now.

Autopsy↗
PubMed2001

Diamond stents for palliation of malignant bile duct obstruction: a prospective multicenter evaluation.

BACKGROUND AND STUDY AIMS: Various types of self-expandable metal stents have been introduced for biliary drainage in patients with malignant jaundice, showing prolonged patency compared with plastic endoprostheses. However, there has only been prolonged experience with a meaningful number of patients using the Wallstent. We evaluated the Diamond stent, a self-expanding uncoated biliary metal stent, in a prospective uncontrolled multicenter setting. PATIENTS AND METHODS: The eligibility criterion was obstructive jaundice due to inoperable malignant disease. Between August 1995 and January 2000, 126 patients, who received a total of 134 Diamond stents in four European centers, were followed prospectively. RESULTS: Technical and clinical success rates were 96 % and 98 %, respectively. No major procedure-related complications occurred. The 30-day mortality rate was 13 %. Stent occlusion occurred in 28 patients (22 %). Overall median stent patency was 477 days; overall median survival was 173 days. Stent occlusion, confirmed by endoscopic retrograde cholangiopancreatography, was successfully treated with plastic stents in all patients. Cost analysis revealed estimated costs of 3440 euros per patient for palliative treatment with the Diamond stent. CONCLUSIONS: The Diamond stent compares favorably with other biliary metal stents for patients requiring biliary drainage of malignant jaundice.

Adult↗
PubMed2001

Estrogen sulfamates: a new approach to oral estrogen therapy.

Sulfamate substitution (-O-SO2-NH2) at carbon atom 3 of the steroid skeleton leads to orally active prodrugs of estrogens with much higher systemic, but lower hepatic, estrogenic activity than their parent steroids. This dissociation is achieved by first passage through the liver in erythrocytes, followed by systemic hydrolysis which releases the 'parent' estrogen. In the rat, orally administered tritiated estradiol sulfamate, unlike estradiol, appears in the circulation at high concentrations. At Cmax, approximately one third of the administered dose forms a depot in the circulation (98% in erythrocytes, 2% in plasma). Significant estradiol, estrone and estrone sulfate concentrations were recorded in plasma during depletion of the red blood cell pool. Estradiol sulfamate (J995) has no estrogen receptor affinity per se or estrogenic activity in vitro ( i.e. without hydrolysis). Its oral uterotropic activity in rats is approximately 100 times greater than that of estradiol, however, its hepatotropic activity is only marginally elevated. These functions include bile secretion, the secretion of angiotensinogen, lipoproteins (total and high-density lipoprotein cholesterol) and insulin-like growth factor I (IGF-I). Orally administred estradiol sulfamate led to systemic estrogenic effects without significant hepatic responses, whereas estradiol and other 'conventional' estrogens exerted parallel systemic and hepatic estrogenic effects. Sulfamate technology represents an approach to the use of natural estrogens for fertility control and hormone replacement therapy in both genders. In this context, reduced effects on hemostatic factors, angiotensinogen, bile and IGF-I secretion seem the most important aspects. In addition, blood concentrations of estrogens are less variable than with conventional estrogens.

Administration, Oral↗