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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of biomedical science 1 (1993), S. 1-1 
    ISSN: 1423-0127
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1423-0127
    Keywords: Avascular necrosis ; Femoral head ; Corticosteroid ; Laser Doppler velocimeter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Avascular necrosis of the femoral head is one of the common problems in orthopedic practice in Taiwan. The subchondral bone loses its blood supply which weakens its biomechanical support. Steroid overuse is one of many possible etiologies in reducing blood flow to the femoral head. Laser Doppler velocimeter is a precise monitor of regional blood flow of bone which is expressed in perfusion units (PU). In the control group the rabbits were injected with normal saline and there were no statistical differences between blood flow to the right hip (39.26±5.64 PU) and left hip (38.58±4.35 PU). In group B a weekly injection of methylprednisolone into rabbits for 6 weeks demonstrated the reduction of blood flow of femoral head (24.74±3.13 PU) by the laser Doppler velocimeter. The flow decreased further (15.93±2.33 PU) by 12 weeks of steroid treatment. In group C after a weekly injection of steroid for 6 weeks the flow became 31.63±4.79 PU. The steroid was then discontinued for 3 weeks and the flow was 34.6±1.34 PU. In group D the blood flow was 25.89±4.01 PU after 6 weeks of steroid treatment and we stopped the steroid for 6 weeks, the blood flow became 29.86±2.59 PU. The merit of our experiment established a model of study in avascular necrosis of the femoral head in rabbits.
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  • 3
    ISSN: 1423-0127
    Keywords: Fragile X ; Chromosome abnormalities ; Mental retardation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 560 blood samples collected from mentally retarded children in Taipei were karyotypically analyzed for the incidence of fragile X and other chromosome abnormalities. The fragile site at Xq27.3 was observed in 18 patients (3.21%), 11 males and 7 females, out of the 560 blood cultures using M medium. Down syndrome (6.25%), 24 males and 11 females, was the other major category of abnormality. Other abnormalities, including inversion, translocation, deletion, duplication, ring as well as an extra marker chromosome were observed. The overall incidence of chromosomal abnormalities in these children was 14.82%.
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  • 4
    ISSN: 1423-0127
    Keywords: Common allergenic epitope ; Minor allergen ; Bermuda grass pollen ; Cyn dI ; Lol pI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present study disclosed the cross-reactivity between Bermuda grass pollen (BGP) and other grass pollens using monoclonal antibodies (MAbs) and polyclonal antiserum. MAb 9–13, directed against a group of minor allergens of BGP (Cyn d Bd68K, 48K, 38K) was found to cross-react with extracts of ten other grass pollens. Immunoblotting assays illustrated that MAb 9–13 cross-reacted with multiple components of most of these pollens, and the major cross-reactive components had molecular weights of 29–36 kD. The cross-reactivity between BGP andLol pI, the group I allergen of rye grass pollen, was further evaluated;Lol pI was recognized by MAb 9–13, but not by our MAbs/polyclonal antiserum againstCyn dI, the major allergen of BGP. These results suggest that the epitope recognized by MAb 9–13 is a common (C) epitope shared byLol pI andCyn d Bd68K, 48K, 38K, andCyn dI does not share significant antigenicity withLol pI. In a modified radio-allergosorbent test, IgE antibodies in the serum of BGP-allergic patients reacted mildly with C-epitope-bearing components of both BGP and rye grass pollens, and this binding could be blocked specifically by MAb 9–13. This suggests that in addition to an antigenic cross-reaction, the C epitope can also lead to an allergenic cross-reaction.
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  • 5
    ISSN: 1423-0127
    Keywords: Polyphenols ; Benzene metabolites ; Hydroquinone ; Catechol ; 1,2,4-Benzenetriol ; Pyrogallol ; Active oxygen species ; Hydrogen peroxide ; Superoxide radical ; Hydroxyl free radical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Benzene is strongly suspected of being an animal and human carcinogen, but the mechanisms by which it induces tumors of lymphoid and hematopoietic organs are unknown. Production of active oxygen species from benzene metabolites [hydroquinone (HQ), catechol and 1,2,4-benzenetriol (1,2,4-BT) and related polyphenols (resorcinol, pyrogallol and phloroglucinol) are investigated. Pyrogallol and 1,2,4-BT can produce H2O2, O 2 − and·OH simultaneously, and have powerful mutagenic potential. Resorcinol and phloroglucinol cannot produce all of the active oxygen species, and show no mutagenic effects. Catechol can produce H2O2, but cannot produce O 2 − and·OH, and has no mutagenic activity. These data strongly support the hypothesis that benzene metabolites can cause mutagenicity via the generation of oxygen radicals. Although HQ produces H2O2 only, and less than produced by pyrogallol and 1,2,4-BT, the mutagenicity of HQ is higher. The results indicate that HQ may act via another mechanism to cause mutagenicity. In the presence of trace metal ions, the reactivity of polyphenols is increased. The biological significance of these phenomena are investigated and discussed.
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  • 6
    ISSN: 1423-0127
    Keywords: Atria, human ; Cardiomyocytes ; Prostaglandin ; Action potential ; Contractile force ; Ionic currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The aim of this study was to characterize the electropharmacological effects of prostacyclin (PGI2) in human atrial fibers and cardiomyocytes. Atrial tissues obtained from the hearts of 28 patients undergoing corrective cardiac surgery were used. Transmembrane action potentials were recorded using a conventional microelectrode technique, and twitch force by a transducer. Effects of PGI2 (1 nM–10 µM) on action potential characteristics and contraction of atrial fibers were evaluated in normal [K]o (4 mM) and high [K]o (27 mM) in the absence and presence of cardiotonic agents. In addition, atrial and ventricular myocytes were isolated enzymatically from atrial tissues and hearts of 4 patients undergoing cardiac transplant. The effects of PGI2 on Na- and Ca-dependent inward currents (INa and ICa) of cardiomyocytes were tested. In 9 human atrial fibers showing fast-response action potentials (mean dV/dtmax = 101 ± 15 Vs−1) in 4 mM [K]o, PGI2 did not influence dV/dtmax of phase 0 depolarization even at 1 µM. However, at a concentration as low as 10 nM, PGI2 depressed spontaneous rhythms or slow-response action potentials in high-K-depolarized fibers. PGI2 also depressed delayed afterdepolarizations and aftercontractions induced by cardiotonic agents. In isolated cardiomyocytes, PGI2 reduced ICa but not INa. The present findings show that, in human atrial fibers and cardiomyocytes, PGI2 induces greater depressant effects on the slow-response action potential, ICa and triggered activity than on the fast-response action potential. It is suggested that PGI2 may act through a selective reduction of transmembrane Ca influx.
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  • 7
    ISSN: 1423-0127
    Keywords: Adenosine ; Adenosine deaminase deficiency ; Apoptosis ; c-myc ; DNA fragmentation ; Proto-oncogene ; L1210 lymphocytic leukemia cells ; Severe combined immunodeficiency syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract High concentrations of adenosine (Ado), when added to L1210 lymphocytic leukemia cells, resulted in apoptosis or programmed cell death. The apoptotic process was accompanied by distinct morphological changes including chromatin condensation and blebbing of plasma membranes. Extensive DNA fragmentation was correlated with Ado concentrations. Furthermore, apoptosis in these cells was preceded by an early but transient expression of c-myc proto-oncogene, and was not influenced by homocysteine thiolactone added to the cells. Since severe combined immunodeficiency (SCID) is associated with a deficiency of adenosine deaminase, leading to defects in both cellular and humoral immunity, Ado-induced apoptosis may thus be a contributing factor in the pathology of SCID.
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  • 8
    ISSN: 1423-0127
    Keywords: Polyphenolic catechins ; HIV reverse transcriptase activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Three polyphenolic catechins, epigallocatechin (1), epicatechin-3-O-gallate (2) and epigallocatechin-3-O-gallate (3), were isolated from Chinese green tea, Ti-Kaun-Yin(Camellia sinensis) and demonstrated as a new class of human immunodeficiency virus-reverse transcriptase (HIV-RT) inhibitor. The concentrations required for 50% inhibition for the compounds (1), (2) and (3) were 7.80, 0.32 and 0.68 µM, respectively. The polyphenolic catechins with a galloyl group at the 3 position were potent inhibitors of HIV-RT. Kinetic analysis indicated that the polyphenolic catechins were competitive inhibitors with respect to the template-primer (rA)n(dT)12–18 and noncompetitive inhibitors to dTTP.
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  • 9
    ISSN: 1423-0127
    Keywords: Sulfated glucuronyl glycolipids ; Motor and sensory nerve ; Myelin ; Axolemma ; HNK-1 ; Polyneuropathy ; IgM paraprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sulfated glucuronyl glycolipids (SGGL) have been implicated as important target antigens in patients with demyelinating polyneuropathy and IgM paraproteinemia. Sulfated glucuronyl paragloboside (SGPG), a major species of SGGL, was identified in the subcellular fractions of human peripheral motor and sensory nerves using a simple and quantitative method. SGPG was found to be concentrated in the myelin-enriched fractions of both motor and sensory nerves (1.3±0.3 and 1.5±0.4 µg/mg protein, respectively), whereas its concentration was 0.9±0.2 and 1.8±0.6 µg/mg protein in the axolemma-enriched fractions of motor and sensory nerves, respectively. Our finding that SGPG is more abundant in the human sensory nerve axolemma-enriched fraction may account for the clinical and pathological observations that the lesions are more heavily concentrated in the sensory nerve than in other parts of the nerve tissues in this disorder.
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  • 10
    ISSN: 1423-0127
    Keywords: Inward K+ rectification ; Negative slope conductance ; Depolarization-induced activity ; Early afterdepolarizations ; Cromakalim ; Barium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The role of the inward K+ rectifier in the repetitive activity at depolarized levels was studied in guinea pig single ventricular myocytes by voltage- and current-clamp methods. In action potentials arrested at the plateau by a depolarizing current, small superimposed hyperpolarizing currents caused much larger voltage displacements than at the resting potential and sometimes induced a regenerative repolarization. Around −20 mV, sub- and suprathreshold repetitive inward currents were found. In the same voltage range, small hyperpolarizing currents reversed their polarity. During depolarizing voltage-clamp ramps, around −20 mV there was a sudden decrease in the outward current (Ins: current underlying the negative slope in the inward K+ rectifier steady state I−V relation). During repolarizing ramps, the reincrease in outward current was smaller and slower. During depolarizing and repolarizing current ramps, sudden voltage displacements showed a similar asymmetry. Repetitive Ins could continue as long as the potential was kept at the level at which they appeared. Depolarizing voltage-clamp steps also caused repetitive Ins and depolarizing current steps induced repetitive slow responses. Cadmium and verapamil reduced Ins amplitude during the depolarizing ramp. BRL 34915 (cromakalim), an opener of the ATP-sensitive K+ channel, eliminated the negative slope and Ins, whereas barium increased Ins frequency (an effect abolished by adding BRL). Depolarization-induced slow responses persisted in an NaCl-Ca-free solution. Thus, the mechanism of repetitive activity at the depolarized level appears to be related to the presence of the negative slope in the inward K+ rectifier I–V relation.
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