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Biomedical subjects

M Albrecht

Publications and source records attributed to M Albrecht.

At least 19 recordsLinked to original sources
PubMed2003

The interleukin-6 promoter polymorphism is associated with elevated leukocyte, lymphocyte, and monocyte counts and reduced physical fitness in young healthy smokers.

Smoking and interleukin-6 are important factors in driving inflammation. This study assessed the relationship between smoking, interleukin-6 genotype, physical fitness, and peripheral blood count in healthy young men. For this interleukin-6 promoter polymorphism -174 genotype-phenotype association study 1,929 healthy German male aviators recruited at the central German Air Force Institute of Aviation Medicine were stratified by smoking habits. Cardiovascular fitness was expressed as maximal physical working capacity (PWCmax) in watts per kilogram body weight as assessed by maximal exercise testing by cycle ergometry up to physical exhaustion. Smokers had higher leukocyte and lymphocyte counts than nonsmokers and lower PWCmax. In the overall study population the C allele of the interleukin-6 polymorphism was weakly associated with elevated leukocytes and lymphocytes; in nonsmokers the interleukin-6 polymorphism was not associated with altered phenotypes, but in smokers the interleukin-6 C allele was associated with higher leukocytes, lymphocytes, and monocytes and with lower PWCmax. Smoking is thus associated with elevated leukocytes and lymphocytes and with reduced physical fitness. Gene carriers with the interleukin-6 C allele may suffer particularly from cigarette smoking.

Adult↗
PubMed2003

Relation of body mass index, physical fitness, and the cardiovascular risk profile in 3127 young normal weight men with an apparently optimal lifestyle.

Obesity is a well-accepted cardiovascular risk factor associated with hypertension and hyperlipidaemia. A body mass index (BMI) within the range of 18.5-25 kg/m(2) is considered normal. To prevent cardiovascular diseases regular physical activity and abstinence from smoking are strongly recommended. Since it is not evident that a lower optimal threshold exists concerning cardiovascular risk factors if other lifestyle conditions are apparently optimised, we studied the relation between BMI and vascular risk factors in 3127 hyperhealthy Caucasian males. They were aged between 18 and 23 y, were nonsmokers, without regular alcohol intake, and had at least 3 h of sports activity per week. Their BMI was below 25 kg/m(2). Low BMI revealed to be significantly associated with high physical fitness, low blood pressure, and low serum lipids. The lower the BMI was, the more favourable these parameters were. Thus, the threshold for an optimal BMI concerning cardiovascular risk factors might be far below 25 kg/m(2) even if other lifestyle conditions are apparently optimal.

Adolescent↗
PubMed2003

Relation between the angiotensinogen (AGT) M235T gene polymorphism and blood pressure in a large, homogeneous study population.

The aim of this study was to assess the association of the angiotensinogen M235T polymorphism with arterial blood pressure (BP) at rest and under physical stress in a homogeneous large-scale study population. In all, 1903 men who passed routine medical examination for military flying duty were recruited. BP and heart rate were measured at rest, during, and after bicycle ergometry. Genotyping for the AGT M235T polymorphism was carried out by PCR and RFLP technique. The AGT T235 allele was associated with a significantly higher diastolic BP (n=1903; MM 81+/-8, MT 83+/-7, TT 83+/-8; P=0.003). Pulse pressure (PP) at rest differed significantly between AGT genotypes (n=1903; MM 51+/-10 mmHg, MT 49+/-10 mmHg, TT 49+/-10 mmHg; P=0.001). During physical activity, BP values showed no significant difference between genotypes. In healthy young men, the AGT T235 allele is significantly associated with elevated diastolic BP but also reduced PP at rest. During physical activity, the AGT polymorphism had no impact on blood pressure, indicating the existence of other counteracting mechanisms, which might balance the influence of this gene.

Adult↗
PubMed2003

The vitamin D receptor gene variant and physical activity predicts fasting glucose levels in healthy young men.

AIMS: Vitamin D can influence lipolysis and insulin secretion. A common genetic polymorphism of the vitamin D receptor (VDR), which has been found to be associated with bone mineral density, has been reported to be also associated with Type 2 diabetes mellitus (DM). To test the influence of the VDR polymorphism on fasting glucose in healthy young men before the onset of Type 2 DM, we studied a homogeneous population of aircrew members. METHODS: A total of 1539 individuals were recruited during routine medical qualification for flying duty. Physical activity was assessed in all individuals and categorized into low physical activity ( 3 h per week). The BsmI VDR polymorphism was analysed by polymerase chain reaction. On the day of blood testing the individuals were fasting for at least 8 h overnight. Serum glucose was measured within 60 min after sampling venous blood. RESULTS: In young males with low physical activity (n = 752) gene carriers with the VDR genotype BB (n = 137) have significantly (P < 0.001) higher levels of fasting glucose (5.61 +/- 0.49 mmol/l) than gene carriers with the genotype Bb (n = 370; 5.44 +/- 0.44 mmol/l) or bb (n = 245; 5.38 +/- 0.44 mmol/l). Of BB gene carriers, 47% had fasting glucose levels > 5.55 mmol/l compared with 36% of Bb gene carriers and 34% of bb gene carriers (P = 0.018). This effect is absent in gene carriers with high physical activity (n = 787). CONCLUSIONS: The VDR genotype is associated with altered fasting glucose levels in young men with low physical activity. If this association is confirmed in other populations it might be worthwhile studying the particular benefits of an exercise programme in dependents of the VDR genotype.

Adult↗
PubMed2002

Novel sb induced reconstruction of the (113) surface of ge.

Sb induces on Ge(113) a c(2 x 2) reconstruction in which Sb breaks one Ge-Ge bond and occupies an interstitial site, in contrast to Sb adsorption on other Si or Ge surfaces. Sb saturates the three dangling bonds per unit cell of the (113) surface inducing a large strain which is released by occupation of the interstitial site. Two neighboring Sb at interstitial sites form a dimer. The structure has been determined by x-ray diffraction, applying direct methods, and ab initio density-functional-theory calculations. The adsorption geometry and the high binding energy lead one to expect that Sb cannot be used as a surfactant for the growth of Si/Ge layers on the (113) surface.

Journal Article↗
PubMed2002

Application of Nomarski interference contrast microscopy as a thickness monitor in the preparation of transparent, SiC-based, cross-sectional TEM samples.

Reflected light optical microscopy using a Nomarski prism and a differential interference contrast filter have been employed in concert to achieve a technique that provides an accurate color reference for thickness during the dimpling and ion milling of transparent transmission electron microscopy samples of 6H-SiC(000 1) wafers. The samples had thin films of AIN, GaN, and Au deposited on the SiC substrate. A sequence of variously colored primary and secondary interference bands was observed when the SiC was thinner than 20 microm using an optical microscope. The color bands were correlated with the TEM sample thickness as measured via scanning electron microscopy. The interference contrast was used to provide an indication of the dimpling rate, the ion milling rate, and also the most probable location of perforation, which are useful to reduce sample breakage. The application of pressure during the initial cross-sectional preparation reduced the separation of the two halves of the sample sandwich and resulted in increased shielding of the film surface from ion milling damage.

Journal Article↗
PubMed2002

Effects of dexamethasone on proliferation of and fibronectin synthesis by human primary prostatic stromal cells in vitro.

Glucocorticoids are anti inflammatory stress hormones and have been suggested to be involved in a large number of pathological processes. To test the effects of glucocorticoids on stromal prostatic cell growth and proliferation in vitro, the influence of a synthetic glucocorticoid (dexamethasone, dex) on recently established human primary cells from prostatic stroma (hPCPs) was analysed. The localization and distribution of the glucocorticoid receptor (GR) was investigated by immunohistochemistry. In addition, expression of the active isoform of the receptor (alpha-GR) was examined by reverse transcription PCR, and the effect of different doses of dex on proliferation of the stromal cells evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and amido black assays. alpha-GR mRNA was expressed by the hPCPs, and the GR protein was detected in the cytoplasm and nucleus of these cells. Incubating the cells with dex resulted in an enhanced cell proliferation that was mainly restricted to the fibroblasts. Moreover, fibronectin (FN) gene expression and secretion of the protein was increased by high doses of dex (> or = 10(-8) M), whereas low doses of dex (10(-10)M) showed no effect. Human prostatic stromal cells show sensitivity to dex in vitro, resulting in an increase in cell proliferation and FN synthesis. The authors assume that locally accumulating glucocorticoids can also influence the regulation of cell growth and extracellular matrix synthesis in the human prostate in vivo and may play a role in the pathologically altered prostate.

Cell Division↗
PubMed2001

Response-adapted radiotherapy in the treatment of pediatric Hodgkin's disease: an interim report at 5 years of the German GPOH-HD 95 trial.

PURPOSE: A multinational trial on pediatric Hodgkin's disease (HD) with the aim to reduce the risk of long-term toxicity of combined modality treatment by restricting dose and volume of radiation therapy (RT) while maintaining the excellent treatment results of previous German multicenter trials (DAL-HD82-90). METHODS AND MATERIALS: Patients were treated according to stage of disease (CS) and defined risk factors in three treatment groups (TG) with 2, 4, or 6 cycles of combination chemotherapy. When a complete remission (CR) had been achieved, treatment was terminated without RT independent of initial stage or tumor bulk. Patients with a partial remission (PR) of >75% tumor regression were irradiated with 20 Gy using modified involved fields; in the case of PR <75% RT dose was 30 Gy, residual masses >50 mL received 35 Gy. RESULTS: From August 1995 to July 2000 a total of 956 patients have been registered, 830 as trial patients, 39% in TG1, 27% in TG2, 34% in TG3. 827 patients were evaluable by June 2001 with a median follow-up of 38 months. Chemotherapy (CTx) resulted in CR in 22%, PR >75% in 62%, PR <75% in 12%. Event-free survival (EFS) for the entire group is 90% (SD 0.01), for TG1 94%, TG2 91%, and TG3 84%; the overall survival is 97% in Kaplan-Meier-analysis. Relapse-free survival (RFS) is superior for patients with RT after PR (93%) than for those without RT after CR (89%); the difference is significant (p = 0.01) for advanced stages, however not in TG1. Seventy-two events were observed by June 2001: 28 progressions during the initial therapy or within the first 3 months, 38 relapses, 3 second malignancies, three fatal accidents or infections; 18 patients have died. CONCLUSION: Treatment results of the GPOH-HD 95 trial are excellent thus far. The reduction of RT dose and volume in PR has not caused a significant impairment of overall and event-free survival in comparison to the previous German trials; however, failure rates are higher in advanced stages when RT is omitted after achieving a CR. It is too early to tell whether the HD 95 protocol will be successful in reducing late toxicity.

Adolescent↗
PubMed2001

Dinuclear titanium(IV) complexes from amino acid bridged dicatechol ligands: formation, structure, and conformational analysis.

Amino acid bridged dicatechol ligands 3a-e-H4 form dinuclear double-stranded coordination compounds [(3a-e)2Ti2(OCH3)2]2- with titanium(IV) ions. Due to the directionality of the ligands, the chirality of the strand, and the chiral complex units, up to seven isomers, I-VII, can be obtained for the double-stranded complexes of ligands 3a-e-H4. The composition of the mixture of isomeric compounds in solution is strongly dependent on the conditions of complex formation. Under thermodynamic control, only a few isomers are obtained, one of which is the major component of the mixture. X-ray structure analyses were performed for K2[(3b)2Ti2(OH)2] and K2[(3d)2Ti2(OH)2] (type I), and for the meso complex Na2[(3e)(3e')Ti2(OCH3)2]. A conformational analysis that uses Ramachandrans method revealed that the conformation of the amino acids in the ligand strands can be compared with those found for amino acids in helical peptide structures. The most favored isomer of [(3)2Ti2(OCH3)2]2- appears to be of type I, with the catecholamide unit located at the N terminus of the ligand strand that binds to a lambda-configurated titanium(IV) complex unit and the dihydroxybenzyl group at the C terminus that coordinates to a delta-configurated titanium(IV) complex unit. The lambda configuration at the N terminus induces the conformation of a right-handed helix in the amino acid residue, while the delta configuration induces the less favored left-handed helix.

Amino Acids↗
PubMed2001

C(arenium)-C(alkyl) bond making and breaking: key process in the platinum-mediated C(aryl)-C(alkyl) bond formation. Analogies to organic electrophilic aromatic substitution.

The reaction of cationic platinum aqua complexes 2 [Pt(C(6)H(2)[CH(2)NMe(2)](2)-E-4)(OH(2))](X') (X' = SO(3)CF(3), BF(4)) with alkyl halides RX gave various air-stable arenium complexes 3-5 containing a new C-C bond (R = Me, 3; Et, 4; Bn, 5). Electron-releasing oxo-substituents on the aromatic ligand (E = e.g., OH, b; OMe, c) enhance the reactivity of the aqua complex 2 and were essential for arenium formation from alkyl halides different from MeX. This process is initiated by oxidative addition of alkyl halides to the platinum(II) center of 2, which affords (alkyl)(aryl) platinum(IV) complexes (e.g., 9, alkyl = benzyl) as intermediates. Spectroscopic analyses provided direct evidence for a subsequent reversible 1,2-sigmatropic shift of the alkyl group along the Pt-C(aryl) bond, which is identical to repetitive C(arenium)-C(alkyl) bond making and breaking and concerted metal reduction and oxidation. Temperature-dependent NMR spectroscopy revealed DeltaH degrees = -1.3 (+/- 0.1) kJ mol(-1), DeltaS degrees = +3.8 (+/- 0.2) J mol(-1) K(-1), and DeltaG degrees (298) = -2.4 (+/- 0.1) kJ mol(-1) for the formation of the arenium complex 5b from 9 involving the migration of a benzyl group. The arenium complexes were transformed to cyclohexadiene-type addition products 7 or to demetalated alkyl-substituted arenes, 8, thus completing the platinum-mediated formation of a sp(2)-sp(3) C-C bond which is analogous to the aromatic substitution of a [PtX](+) unit by an alkyl cation R(+). The formation of related trimethylsilyl arenium complexes 6 suggests arenium complexes as key intermediates, not only in (metal-mediated) sp(2)-sp(3) C-C bond making and breaking but also in silyl-directed cyclometalation.

Journal Article↗
PubMed2001

Multiple use of soluble metallodendritic materials as catalysts and dyes.

Different sizes of core-functionalized metallodendritic wedges were prepared by anchoring sensor-active arylplatinum(II) sites at the focal point of Fréchet-type polyether dendritic wedges of various generations. The strong color of these metallodendrimers in the presence of SO2 was used to assess the permeability of nanofiltration membranes (molecular weight cut-off of 400 dalton) at ambient pressure. A primary result of these studies is that dendrimers do not have to be exceptionally large for successful retention. Hence, nanofiltration, membrane-capped. immersion vials were developed, which operate as sensor devices when loaded with metallodendrimers with good retention properties. Appropriate substitution of the dye site at the focal point of these metallodendritic wedges by a catalytically active group afforded dendritic catalysts that exhibit essentially the same physical properties (shape, retention) as the corresponding dyefunctionalized dendritic wedges. When this homogeneous catalyst is compartmentalized in membrane-capped vials, a unique and convenient method for its retrieval from product solutions is available. Moreover, such immobilized metallodendritic catalysts can be regenerated and stored for months without losing their activity; this provides access for the development of novel sustainable homogeneous catalysts.

Journal Article↗
PubMed2001

Identification and characterization of neutral endopeptidase (EC 3. 4. 24. 11) from human prostasomes--localization in prostatic tissue and cell lines.

BACKGROUND: An antibody directed against a 100 kDa protein was immunoselected from a polyvalent antiserum against human prostasomes. The antibody as well as biochemical characteristics of the respective antigen were used to study the structural relationship of the latter with prostate membrane specific antigen (PMSA), another 100 kDa membrane protein of the prostate. METHODS: The isolated purified 100 kDa protein was characterized by tryptic degradation, aminoacid-sequencing and mass spectroscopy peptide-fingerprinting as well as mono-saccharide analysis and lectin binding and identified as a prostasomal neutral endopeptidase (NEP, EC 3.4.24.11). Immunohistochemistry, immunoelectron microscopy, in situ hybridization, and RT-PCR were performed to analyze the expression and distribution of the protein in normal and malignant human prostatic tissues and cell lines. RESULTS: Prostatic NEP, which has no relationship with PMSA, is a glycosylated, integral membrane protein type II. The prevalent glycosyl residues are NeuNAc, GlcNAc, GalNAc, Gal, Man, Fuc. NEP-mRNA is expressed in human prostatic epithelial and some stromal cells. NEP-immunoreactivity is strong in normal prostatic epithelium and confined to the apical plasma membrane. During apocrine secretion, the enzyme is released from the secretory cells, contributing to the formation of prostasomes. In prostate cancer specimens, immunoreactivity of apical plasma membranes is lost, while generalized cytoplasmic immunoreactivity develops. CONCLUSIONS: Prostatic secretory cells contain a membrane-bound, highly glycosylated neutral endopeptidase which is restricted to the apical plasma membrane. The enzyme is released from the cells in an apocrine fashion and contributes to the formation of prostasomes. In prostate cancer cells a preferential cytoplasmic localization is observed, pointing to alterations in intracellular targeting.

Amino Acid Sequence↗
PubMed2001

Virologic and CD4 cell response to zidovudine or zidovudine and lamivudine following didanosine treatment of human immunodeficiency virus infection.

To optimize nucleoside reverse transcriptase inhibitor (nRTI) antiretroviral therapy, 137 subjects who had been treated with didanosine monotherapy for more than 3 years in the AIDS Clinical Trials Group (ACTG) 175 study were randomized to zidovudine and didanosine (dual therapy) or zidovudine, didanosine, and lamivudine (triple therapy). Evaluation of early (8 week) change in HIV plasma RNA demonstrated that addition of lamivudine and zidovudine provided significantly greater virologic suppression compared to the addition of zidovudine alone (mean decrease of 1.27 vs. 0.74 log(10) copies/ml, n = 108, p = 0.007). Both dual and triple therapy provided significant long-term decreases (from study entry to mean at Weeks 40 and 48) in HIV plasma RNA: 0.62 and 0.86 log(10) copies/ml, respectively (n = 110). However, the difference between treatments was not significant (p = 0.16). At 48 weeks, 26% of subjects starting study treatment had <500 copies/ml of plasma HIV RNA. The CD4 count response was greater at 4 weeks for triple versus dual therapy: a mean increase of 51 vs. 12 CD4 cells/ml(3) (n = 126, p = 0.039). The difference at Weeks 40 and 48 was not significant (a 22 cell increase vs. a 1 cell decrease, n = 129, p = 0.41). Zidovudine and didanosine treatment, with or without lamivudine, was well tolerated and only 2 of 137 (1.5%) of study participants developed an AIDS-defining event over 48 weeks.

Adult↗
PubMed2001

Effects of inhalation of perfluorocarbon aerosol on oxygenation and pulmonary function compared to PGI2 inhalation in a sheep model of oleic acid-induced lung injury.

OBJECTIVE: To evaluate the effects of PFC aerosol compared to PGI2 aerosol and NaCl aerosol on gas exchange and lung mechanics in oleic acid-induced acute lung injury. DESIGN: A prospective, controlled, randomised, in vivo animal laboratory study. SETTING: Research laboratory at an university hospital. SUBJECTS: Twenty one (n = 21) adult sheep of either gender weighing 26.8+/-6.4 kg. INTERVENTIONS: The animals were randomised to three groups: PFC aerosol (perfluorooctane), PFC group; prostacyclin aerosol (Flolan), PGI2 group; and NaCl aerosol (0.9% sodium chloride solution), control group. After induction of anaesthesia and placement of vascular catheters, lung injury was induced with 0.12 ml x kg(-1) oleic acid. Aerosols were continuously administered for 2 h using a jet nebuliser. Gas exchange, pulmonary mechanic, and haemodynamic parameters were obtained at regular intervals. MEASUREMENTS AND MAIN RESULTS: PFC aerosol increased oxygenation (PaO2) 15 min after the initiation of treatment up to 120 min (P < 0.05). Transpulmonary shunt improved in the PFC group (P < 0.05) while it did not change in the two other groups. PFC aerosol reduced maximum airway pressure (Pmax) (median) significantly from (median) 38 mbar to 32 mbar (P < 0.05). Static compliance improved significantly in the PFC group (P < 0.05). CONCLUSION: The inhalation of a PFC aerosol led to a significant improvement in pulmonary mechanics and gas exchange, which was not observed in the other two groups. These data suggest that a small dose of perfluorocarbon will have beneficial effects on gas exchange and respiratory mechanics. Therefore, the non-invasive aerosol application technique seems to be a reasonable alternative to administer perfluorocarbons in severe lung injury.

Aerosols↗
PubMed2001

Dysfunction of vasomotor reactivity in severe sepsis and septic shock.

OBJECTIVE: Perfusion abnormalities are an overall phenomenon in severe sepsis and septic shock, leading to organ dysfunction. We investigated whether carbon dioxide (CO2)-induced vasomotor reactivity (VMR) is impaired in septic patients, compared with values obtained outside sepsis. DESIGN: Prospective, clinical study. SETTING: Six-bed neurologic critical care unit of a university hospital. PATIENTS AND PARTICIPANTS: Eight consecutive patients with severe sepsis and septic shock. MEASUREMENTS AND RESULTS: CO2-reactivity was measured during and outside a period of severe sepsis or septic shock according to ACCP/SCCM criteria by means of transcranial Doppler sonography and near-infrared spectroscopy (NIRS). VMR was calculated as the percentage change of cerebral blood flow velocity (normalized CO2-reactivity, NCR) and absolute changes in concentration of oxygenated hemoglobin, deoxygenated hemoglobin, total hemoglobin (HbO2, Hb, HbT) and Hbdiff (difference between HbO2 and Hb) in micromol/l per 1% increase in end-tidal CO2 (CR-HbO2, CR-Hb, CR-HbT, CR-Hbdiff). NCR and NIRS-reactivities were significantly reduced during severe sepsis and septic shock compared with values outside sepsis (mean, SD, Wilcoxon): NCR 11.0 (7.1) versus 30.7 (13.0), p < 0.02; CR-HbO2 0.70 (0.61) versus 2.33 (1.11), p < 0.02; CR-Hb -0.17 (0.74) versus -1.42 (1.28), p < 0.04; CR-HbT 0.53 (0.48) versus 1.05 (0.40), p < 0.03; CR-Hbdiff 0.91 (1.33) versus 3.75 (2.33), p < 0.02. This indicates a severely disturbed VMR. CONCLUSIONS: In the advent of a disturbed cerebral autoregulation, critical drops in blood pressure during sepsis are transferred directly into the vascular bed, leading to cerebral hypoperfusion. This mechanism might contribute to the pathogenesis of septic encephalopathy.

Aged↗
PubMed2001

The fat redistribution syndrome in patients infected with HIV: measurements of body shape abnormalities.

OBJECTIVE: To describe the body shape changes in the syndrome of fat redistribution or lipodystrophy seen in patients infected with HIV. DESIGN: An objective description of patients with HIV with fat redistribution syndrome. Body-height, weight, shape, and composition were measured by anthropometrics and biolectrical impedance analysis by a single observer. Clinical data were collected by chart review. SUBJECTS/SETTING: Thirty-nine patients with HIV receiving primary HIV care at a university hospital-affiliated infectious disease clinic who presented with complaints of body shape changes or who were referred by their primary care providers for body shape changes. ANALYSIS: Descriptive statistics were performed. RESULTS: Four of the 39 patients (10%) had not used protease inhibitor therapy. HIV status (by clinical presentation, CD4 and VL) varied widely. Laboratory abnormalities were moderate. Percent body fat differed widely when measured by bioelectrical impedance analysis and anthropometry (23% vs 13%). The mean body mass index was 25.6 kg/m2 for men and 25.8 kg/m2 for women. The mean waist/hip ratio was above normal, at 1.02. The mean mid-arm circumference and triceps skinfolds were below national standards for both men (30.4 cm and 8.1 mm, respectively) and women (26.7 cm and 7.5 mm, respectively). Nine patients (23%) had an increased dorso-cervical pad. Seventeen patients returned for follow-up measurements at 3 months; no significant differences were found between baseline and follow-up measurements. CONCLUSIONS: The waist/hip ratio, mid-arm and mid-thigh circumference, and triceps skinfolds were useful measures to define and follow the fat redistribution syndrome in patients with HIV. These body composition changes were not transitory in this short follow-up period.

Adipose Tissue↗