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Biomedical subjects

A Hahn

Publications and source records attributed to A Hahn.

At least 73 records · Page 4Linked to original sources
PubMed1998

Altitude training at 2690m does not increase total haemoglobin mass or sea level VO2max in world champion track cyclists.

Haemoglobin mass (Hb mass), maximum oxygen consumption (VO2max), simulated 4000 m individual pursuit cycling performance (IP4000), and haematological markers of red blood cell (RBC) turnover were measured in 8 male cyclists before and after (A) 31 d of altitude training at 2690 m. The dependent variables were measured serially after altitude on d A3-4, A8-9 and A20-21. There was no significant change in Hb mass over the course of the study and VO2max at d A9 was significantly lower than the baseline value (79.3 +/- 0.7 versus 81.4 +/- 0.6 ml x kg(-1) x min(-1), respectively). No increase in Hb mass or VO2max was probably due to initial values being close to the natural physiological limit with little scope for further change. When the IP4000 was analysed as a function of the best score on any of the three test days after altitude training there was a 4% improvement that was not reflected in a corresponding change in VO2max or Hb mass. RBC creatine concentration was significantly reduced after altitude training, suggesting a decrease in the average age of the RBC population. However, measurement of reticulocyte number and serum concentrations of erythropoietin, haptoglobin and bilirubin before and after altitude provided no evidence of increased RBC turnover. The data suggest that for these elite cyclists any benefit of altitude training was not from changes in VO2max or Hb mass, although this does not exclude the possibility of improved anaerobic capacity.

Adult↗
PubMed1998

LU 302 872 and its racemate (LU 224 332) show balanced endothelin-A/B receptor affinity, high oral activity, and inhibit human prostate tissue contractions.

LU 302 872 (racemate LU 224 332) is a new glycerinic acid derivative related to the selective ETA receptor antagonist LU 135 252. LU 302 872 exhibits high and balanced affinity to ETA and ETB receptors (Ki 2.2 and 5.8 nmol/L), whereas LU 135 252 is ETA-selective (Ki 1.4 and 184 nmol/L). Two hours after oral treatment of rats with 10 mg/kg of LU 302 872 or of LU 135 252, the big ET-1-induced (20 micrograms/kg i.v.) blood pressure increase is inhibited by 59 +/- 8% or 52 +/- 2% (n = 6-8; p < 0.05 vs. control), whereas bosentan is without effect (-6 +/- 7%; n = 6). In guinea pigs, 10 mg/kg p.o. of LU 302 872 inhibited the big ET-1 (20 micrograms/kg i.v.)-induced bronchospasm (reduction in respiratory volume) by 78 +/- 7% (n = 6; p < 0.05), whereas the ETA antagonist LU 135 252 was ineffective (0.2 +/- 37%; n = 6). Hence, a high oral effectiveness of the new ETA/B antagonist could be demonstrated in two species for both an ETA- or an ETB-mediated response. In human prostate tissue (excised during cystectomy in bladder cancer patients), ET-1 and in most cases, the ETB agonist sarafotoxin 6c (S6c) caused contractions of similar magnitude but more sustained than that of norepinephrine (10(-6) mol/L). A high concentration (10(-5) mol/L) of the ETA antagonist LU 135 252 only moderately attenuated ET contractions. The ETA/B antagonist LU 302 872 or its racemate, LU 224 332, dose-dependently inhibited ET-1-induced contractions. S6C dose-response curves, too, were shifted to the right or suppressed by the combined ETA/B antagonist (10(-6) mol/L LU 224 332). LU 302 872 may be a suitable candidate for testing in benign prostate hyperplasia (BPH).

Animals↗
PubMed1998

Novel HLA-A and HLA-B alleles.

Nine novel HLA-A and HLA-B alleles are described: A*2609, A*6803, A*6806, B*1539, B*1540, B*2712, B*4103, B*5109, and B*5603. Most appear to have arisen by gene conversion events. B*5603 appears to have arisen by a reciprocal recombination event joining exon 2 of a B*55/ *56 allele with exon 3 of a B*15 allele. Serologically, the antigen encoded by this allele types with broad B22- and Bw6-specific alloantisera. Also unique, the antigen encoded by B*2712 does not react with B27-specific alloantisera but does react with Bw6-specific alloantisera.

Alleles↗
PubMed1998

Viral genetic evolution in macaques infected with molecularly cloned simian immunodeficiency virus correlates with the extent of persistent viremia.

Genetic evolution of the simian immunodeficiency virus (SIV) envelope glycoprotein was evaluated in a group of six macaques (Macaca nemestrina) infected with the molecularly cloned, moderately pathogenic SIVsm62d. The extent of envelope evolution was subsequently evaluated within the context of the individual pattern of viremia and disease outcome. Two macaques in this cohort developed AIDS by 1.5 years postinoculation (progressors), whereas the remaining four macaques remained asymptomatic (nonprogressors). Compared with the nonprogressor macaques, the two progressor macaques exhibited higher persistent plasma viremia, higher homologous neutralizing antibody titers, and more extensive mutation and evolution in the V1 region of envelope. Although clearly distinct in each of these parameters from the progressors, the four nonprogressors exhibited more individual variability with respect to the extent of persistent viremia and genetic evolution of the V1 region of envelope. The extent of V1 envelope varied from no apparent V1 evolution in a macaque with good viral containment to extensive evolution in one macaque with persistent viremia. This study underscores the critical role of persistent replication in the genetic evolution of SIV.

Amino Acid Sequence↗
PubMed1997

Cloning of the mouse laminin alpha 4 cDNA. Expression in a subset of endothelium.

Endothelial cells express a 400-kDa or 240-kDa laminin alpha chain, depending on their tissue of origin or physiological state [1, 2]. Using differential display and subsequent screening of a mouse endothelial cell cDNA library we here identify the gene coding for the 240-kDa laminin chain as the laminin alpha 4 gene. The complete mouse laminin alpha 4 cDNA sequence is reported and compared with other laminin alpha chains. In situ hybridization of embryonic and new born mouse tissues revealed expression of laminin alpha 4 mRNA in a subset of endothelium, in particular aortic endothelium, endocardium and endothelium of blood vessels in the skin and in the brain. Strong laminin alpha 4 expression by aortic endothelia was confirmed by data obtained from cultured bovine aortic endothelial cells (BAEC). Isolation of laminin from BAEC conditioned medium revealed a Y-shaped molecule in rotary shadowing. Subsequent sequencing of BAEC laminin resulted in laminin alpha 4, beta 1 and gamma 1 amino acid sequences, confirming that laminin alpha 4 is one of the major laminin alpha chains expressed by aortic endothelium not only in the mouse. In addition, strong laminin alpha 4 mRNA expression occurred in peripheral nerves, cardiac muscle, fat, the dermis of the skin and lung stroma of mouse tissues. The data demonstrate a cytokine and progesterone-regulated differential expression of laminin alpha 4 mRNA in mouse endothelium, suggesting a distinct functional role for this laminin chain in endothelium.

Amino Acid Sequence↗
PubMed1997

Clinical implications of maximal respiratory pressure determinations for individuals with Duchenne muscular dystrophy.

OBJECTIVE: To analyze the relationship between disease progression, pulmonary volumes, respiratory muscle strength (maximum inspiratory [MIP] and expiratory [MEP] pressure), and arterial blood gases for patients with Duchenne muscular dystrophy (DMD). DESIGN: An inception cohort study of pulmonary volumes, MIPs, and MEPs, correlated with age and PaCO2 levels and with each other using linear and nonlinear regression analyses. SETTING: Outpatient clinic. PATIENTS: Fifty-two consecutive DMD patients who presented for regular evaluations at a regional DMD center. RESULTS: Maximum expiratory pressures were 47.7% +/- 10.9% of normal in the 167- to 14-year-old patients and decreased linearly thereafter (MEP% = -2.7 x age +73.8; p < .001). Declines in MEP also correlated linearly with expiratory reserve volume (p < .001) and inversely with residual volume (p < .001). By contrast, MIP was 66.3% +/- 19.0% in the 357- to 14-year-old patients and then declined to 30.2% +/- 19.5% after age 14. No linear relationships were found with age but declines did correlate linearly with inspiratory reserve volume (p < .001) and total lung capacity (p < .001). PaCO2 elevations correlated best with decreases in MIP (p < .0001) and appeared when MIP was below 30cmH2O. CONCLUSIONS: Lung volume changes in DMD patients correlate with respiratory muscle weakness, and although inspiratory muscle dysfunction plays a key role in the development of chronic ventilatory insufficiency, reductions in expiratory muscle strength are the first signs of dysfunction and lead to the first episodes of respiratory failure.

Adolescent↗
PubMed1997

Fuzzy sets and fuzzy decision making in nutrition.

OBJECTIVE: This paper demonstrates that a nutrient intake can be described in a differentiated way and can be evaluated by employing fuzzy decision making. It also examines whether fuzzy decision making can simplify nutrition education by small individual improvements in food selection behaviour. RESULTS: The recommendations for nutrient intakes are presented as fuzzy sets, so that the intake of each nutrient can be evaluated by an objective fuzzy value. The evaluation of the harmonic minimum allows, for the first time, that the fuzzy value of an individual nutrient can be stated as a total value. On the basis of individual nutrition assessment, fuzzy logic in connection with fuzzy decision making, allows optimization of meals considering individual food preferences. This makes it possible in nutrition counselling to improve the nutrient intake markedly with relative small changes in food choice. CONCLUSION: Fuzzy decision making can simplify and optimize nutrition education.

Adult↗
PubMed1997

Pain in Guillain-Barré syndrome.

OBJECTIVES: To determine the character, intensity and frequency of pain in Guillain-Barré syndrome (GBS) and to evaluate the response to treatment. DESIGN: A prospective longitudinal study. SETTING: Academic hospital-based practices. PATIENTS: Fifty-five consecutive patients with GBS. INTERVENTIONS: Patients were evaluated on admission and at 2, 4, 8, 16, and 24 weeks. MAIN OUTCOME MEASURES: Character of pain, pain intensity using Visual Analogue Scale ([VAS] 0 to 10 cm) and Present Pain Intensity of McGill Pain Questionnaire, pain relief (VAS 0 to 10 cm), Disability Grading Scale for GBS. RESULTS: Forty-nine patients (89.1%) described pain during the course of their illness. On admission, mean pain intensity (VAS) was 4.7 +/- 3.3. However, 26 patients (47.3%) described pain that was either distressing, horrible, or excruciating (mean VAS, 7.0 +/- 2.0). The most common pain syndromes observed were deep aching back and leg pain and dysesthetic extremity pain. Pain intensity on admission correlated poorly with neurologic disability on admission (r = 0.26, p = 0.06) and throughout the period of study (r < 0.20, p > 0.10). Forty-one patients (74.5%) required opioid analgesics, with 16 (29.0%) receiving parenteral morphine to provide adequate pain relief. CONCLUSIONS: Moderate to severe pain is a common and early symptom of GBS and requires aggressive treatment. Pain intensity on admission is not a predictor of poor prognosis. Back and leg pain usually resolves over the first 8 weeks, but dysesthetic extremity pain may persist longer in 5 to 10% of patients despite motor recovery and the use of adjuvant analgesics.

Back↗
PubMed1996

Selective staining of the cerebellar molecular layer by serum IgG in Miller-Fisher and related syndromes.

During 1 year, we used immunocytochemical staining of human cerebellum to screen 1,488 serums for IgG autoantibodies to Hu and Yo antigens. Three serums had none of the classically described patterns of IgG binding but instead, selectively stained the cerebellar molecular layer. Evaluation of clinical data showed that the patients had either typical Miller Fisher syndrome (MFS) or Guillain-Barré syndrome with ophthalmoplegia. Further analysis by ELISA, assay showed that all three serums had high titers of IgG anti-GQ1b autoantibodies. IgG autoantibody staining of human cerebellum, which is used for the diagnosis of paraneoplastic disorders, may have additional specificity for other, presumably autoimmune, syndromes such as MFS. The specificity of the serum IgG autoantibody binding to the cerebella molecular layer may be related to the ataxia that often occurs in these patients.

Adult↗
PubMed1996

Progressive autologous graft-versus-host disease induced by cyclosporin A.

The development of graft-versus-host disease (GVHD) in patients undergoing allogeneic bone marrow transplantation for leukemias and lymphomas has been associated with a lower incidence of relapse. This phenomenon is thought to be secondary to the anti-tumor effect of adoptively transferred cells. Cyclosporin A (CsA) therapy is known to cause autologous and syngeneic GVHD in experimental models and humans, and has been used in patients undergoing autologous bone marrow transplantation. It has been the consensus to date that CsA-induced autologous GVHD is generally mild, confined to the skin, self-limiting and non-life-threatening. We report by case of severe and progressive GVHD induced by CsA in a child following autologous bone marrow transplantation for acute lymphoblastic leukemia in second remission.

Bone Marrow Transplantation↗
PubMed1995

High-performance liquid chromatographic determination of nicotinic acid and nicotinamide in biological samples applying post-column derivatization resulting in bathmochrome absorption shifts.

An ion-pair reversed-phase high-performance liquid chromatographic procedure for the rapid separation and sensitive quantitation of nicotinic acid (NA) and nicotinamide (NAM) in biological samples was developed. The vitamers were separated within 10 min on an octadecylsilica column applying a linear gradient of tetrabutylammonium phosphate and methanol. NA and NAM were converted to highly absorbing derivatives by a modified König's reaction using a double post-column derivatization arrangement consisting of two pumps and two knitted tubular reactors. The proposed method is highly sensitive and specific and applicable to biological materials as was shown by the analysis of rat intestinal tissue.

Animals↗
PubMed1995

Insulin increases cyclic nucleotide content in human vascular smooth muscle cells: a mechanism potentially involved in insulin-induced modulation of vascular tone.

It has been suggested that insulin exerts a vasodilating effect, but the mechanisms involved are not completely understood. Since cyclic nucleotides mediate the vasodilation induced by endogenous substances, such as prostacyclin and nitric oxide, we aimed to investigate the influence of insulin (concentration range 240-960 pmol/l) on both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) content in human vascular smooth muscle cells. Insulin dose-dependently increased both nucleotides (cAMP: from 0.7 +/- 0.1 to 2.6 +/- 0.4 pmol/10(6) cells, p = 0.0001; cGMP: from 1.3 +/- 0.2 to 3.4 +/- 0.7 pmol/10(6) cells, p = 0.033). This increase is receptor-mediated, since it was blunted when cells were preincubated with the tyrosine kinase inhibitor genistein. The effect of insulin remained significant (p = 0.0001) when preincubation with the phosphodiesterase inhibitor theophylline prevented cyclic nucleotide catabolism. The increase of cGMP was blunted when the cells were preincubated with the guanylate cyclase inhibitor methylene blue, and with the nitric oxide-synthase inhibitor NG-monomethyl-L-arginine. At all the concentrations tested, insulin potentiated the increase of cAMP induced by the stable prostacyclin analogue Iloprost (p = 0.0001), whereas only at 1920 pmol/l did it potentiate the cGMP increase induced by glyceryltrinitrate (p = 0.05). This study demonstrates that the vasodilating effects exerted by insulin may at least in part be attributable to an increase of both cGMP and cAMP via a receptor-mediated activation of adenylate and guanylate cyclases in human vascular smooth muscle cells and that the insulin effect on cGMP is mediated by nitric oxide.

Arterioles↗