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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Physics of atomic nuclei 63 (2000), S. 635-641 
    ISSN: 1063-7788
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The semiclassical approach to modeling atomic collision systems lies between the easy classical model, which is most useful for simple systems in which quantum effects can be neglected, and the full quantum mechanical description, which is generally too difficult for more than simple systems. By adding a mathematical model of quantum-mechanical effects to a classical Hamiltonian, the calculational simplicity of the manybodied classical model can be extended to the quantum realm; the validity of this approach can be measured by the degree to which the semiclassical model can replicate experimental data. Evolving from earlier work by Kirschbaum and Wilets, our model uses momentum-dependent pseudopotentials to exclude particles from quantum mechanically forbidden regions of phase space: a Heisenberg pseudopotential stabilizes the system by preventing atomic electrons from collapsing into the nucleus, while a Pauli pseudopotential holds identical electrons apart in phase space, structuring the electron configuration. This semiclassical model of an atom is then used as a target in collision simulations with a heavy projectile, which is itself treated classically. Collision cross sections are calculated from a series of simulation runs with Monte Carlo target orientations and impact parameters. The model is dialed in to match published experimental proton stopping powers, then applied to other systems of interest. Here, we present stopping and capture cross sections for antiprotons colliding with our semiclassical model of He. Antiproton stopping on He is compared with the results reported recently by the OBELIX group, and initial capture states are discussed in some detail, including a comparison with the quantum-mechanical calculations originally presented by Yamazaki and Ohtsuki and the later paper by Shimamura; among the differences: (1) In our calculations, the angular momentum of captured antiprotons obeys the classical limit l=n, and (2) the angular momentum distribution of our $$He^ + \bar p$$ states extends beyond that of the quantum calculations. It should be emphasized that our calculations are for times much shorter than the metastable lifetimes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 6 (1927), S. 212-213 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1424
    Keywords: Noninactivating cardiac Na+ channels ; Removal of inactivation ; Cardiac Na+ channel protein ; α-subunit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Elementary Na+ currents were recorded in inside-out patches from neonatal rat heart cardiocytes to analyze the influence of a site-directed polyclonal anti-serum against the linker region between the domains III and IV (amino acids 1489–1507 of the cardiac Na+ channel protein) on Na+ channel gating and to test whether this part of the α-subunit may be considered as a target for modifying agents such as the (−)-enantiomer of DPI 201-106. Anti-SLP 1 serum (directed against amino acids 1490–1507) evoked, usually within 10–15 min after cytosolic administration, modified Na+ channel activity. Antiserum-modified Na+ channels retain a single open state but leave, at −60 mV for example, their conducting configuration consistently with an about threefold lower rate than normal Na+ channels. Another outstanding property of noninactivating Na+ channels, enhanced burst activity, may be quite individually pronounced, a surprising result which is difficult to interpret in terms of structure function relations. Removal of inactivation led to an increase of reconstructed peak I Na (indicating a rise in NP o) and changed I Na decay to obey second-order kinetics, i.e., open probability declined slowly but progressively during membrane depolarization. The underlying deactivation process is voltage dependent and responds to a positive voltage shift with a deceleration but may operate even at the same membrane potential with different rates. Iodatemodified Na+ channels exhibit very similar properties including a conserved conductance. They are likewise controlled by an efficient, voltage-dependent deactivation process. Modification by (−)-DPI 201-106 fundamentally contrasts to the influence of anti-SLP 1 serum and the protein reagent iodate since (−)-DPI-modified Na+ channels maintain their open probability for at least 120 msec, i.e., a deactivation process seems lacking. This functional difference suggests that the linker region between the domains III and IV of the α-subunit may not be the only target for (−)-DPI 201-106 and related compounds, if at all.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Platinum, emitted from automobile exhaust catalysts, is mainly oxidised in a humic soil, as described previously [1]. An experiment with nutrient plants was carried out to elucidate the bioavailability and accumulation of these platinum containing species. The plants [Allium cepa L. (Weiß, Frühling), Rephanus sativus L. (Riesenbutter), Vicia faba L. (Hedin, Herzfreya), Zea mays L. (Delis) and Solanum tuberosum L. (Selma)] were grown under natural conditions. For mass balances all ways of platinum transport into and out of the system were monitored during the growing period. Plants growing in untreated soil took up less than 1% of the platinum naturally present in the soil [0.15±0.11 μg kg-1 (78%)]. Plants growing in soil treated with a platinum containing tunnel dust took up slightly more platinum. The comparison of ICPquadrupole-MS results with those obtained by a double focusing magnetic sector ICP-MS showed a strong dependence of the platinum concentration on the Hf-content in the sample. An evaluation method for the correction of the Hf-influence for ICP-quadrupole-MS is presented.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 64 (1990), S. 210-217 
    ISSN: 1432-0738
    Keywords: Aspirin ; Diclofenac ; Diflunisal ; Ibuprofen ; Indomethacin ; Non-steroidal anti-inflammatory agents ; Gastrointestinal toxicity ; Prostaglandins ; Biliary excretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aspirin, diclofenac, diflunisal, ibuprofen and indomethacin were given orally or intravenously to fasted or fed rats. The resulting gastric and intestinal damage was assessed using standard methods. The same drugs were administered to rats with biliary fitulas, and the fraction of drug excreted in bile was quantified using HPLC methods. We found that gastric damage occurred only in the fasted animals and was found to be dose-dependent and related to the amount (r=0.871) and solubility (r=0.909) of the individual drug. As far as acute gastric toxicity is concerned, neither the potency of a drug as an inhibitor of cyclo-oxygenase nor the fraction of unchanged or conjugated agent excreted in bile appeared to be relevant. Secondly, ulcerations of the small intestine occurred in fed animals only. The degree of damage was related to the amount of unchanged or conjugated drug excreted in bile and cyclo-oxygenase inhibitory potency (r=0.873). The administered dose (within the range investigated) and drug solubility appeared not to contribute to intestinal toxicity. It is concluded that, in the rat, acute gastric and intestinal toxicity of non-steroidal anti-inflammatory drugs are due to different mechanisms. Whereas gastric toxicity is strongly influenced by the amount of drug dissolved under the pH conditions in the stomach, intestinal toxicity appears to depend on biliary excretion and enterohepatic circulation of a drug as well as on its potency as an inhibitor of prostaglandin synthesis.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 167 (1938), S. 284-290 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Die Arbeit berichtet über eine Methode, bei welcher mittels eines in die Vagina des Kaninchens eingeführten Ballons Reaktionen aufgezeigt werden, welche gleichförmig mit denen des Uterus verlaufen. Die Methode ist einfach und unblutig. Sie ist geeignet als Test für fraglich uteruserregende Substanzen.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1076
    Keywords: Acute lymphoblastic leukemia ; Hypothyroidism ; L-asparaginase ; Thyroxine binding globulin ; Thyroid hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recently it has been observed that L-asparaginase causes transient thyroxine binding globulin (TBG) deficiency in adults. In the present study we investigated the influence of L-asparaginase on the pituitary-thyroid axis and on the synthesis of TBG. 14 children with acute lymphoblastic leukemia were treated with a combination of L-asparaginase, vincristine, prednisone and daunomycin for remission induction. Thyroid function was monitored by measuring total T4, free T4, total T3, TSH and TBG with specific radioimmunoassays before, during and after treatment. Within 3 weeks of L-asparaginase therapy total T4 fell significantly from 10.7±1.6 to 2.9±1.8 μg/100 ml, free T4 from 1.77±0.4 to 0.94±0.35 ng/100 ml, total T3 from 0.99±0.23 to 0.35±0.2 ng/ml and TBG from 29.4±3.6 to 8.0±3.8 μg/ml. Basal TSH values tinuation of L-asparaginase, but following further treatment with other antileukemic agents, all values became normal within 2–4 weeks. In 6 patients with hypothyroid free T4 values TRH induced TSH release was totally blocked during L-asparaginase therapy. Our data clearly demonstrated that L-asparaginase caused a transient TBG deficiency. Total T4 and T3 were in the hypothyroid range because of low TBG concentrations. In addition to TBG deficiency transient, secondary hypothyroidism occurred in approximately 40–50% of all patients treated with L-asparaginase. These alterations were most likely caused by drug induced inhibition of protein synthesis. Under certain circumstances thyroid hormone replacement might be life-saving in severely ill patients suffering from transient, drug induced hypothyroidism.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 137 (1981), S. 41-44 
    ISSN: 1432-1076
    Keywords: Gynecomastia ; Prolactin ; Gonadotropins ; Steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Pubertal gynecomastia normally occurs as a transient phenomenon of several months duration, whereas marked pubertal gynecomastia (more than 6 cm in diameter) may persist into aduldhood. In the present study the possible involvement of prolactin (PRL) secretion in the development of marked pubertal gynecomastia was investigated. The diurnal variations of PRL, luteinizing hormone (LH), follicle-stimulating hormone (FSH), as well as the basal values of testosterone (T) and estradiol (E2) were determined in 5 pubertal boys with marked gynecomastia and in 5 age-matched controls. Mean age of all patients was 14.4 years. The pubertal development was classified as P 3–4. In comparison to controls, boys with marked gynecomastia revealed no differences in basal values of PRL, LH and FSH, as well as in peak values of all hormones during sleep. The response of PRL, LH and FSH to LHRH/TRH stimulation was normal for pubertal age in both groups. In comparison to controls, decreased mean plasma T levels (P〈0.05) and slightly increased E2 levels (P〈0.05) were found in boys with marked gynecomastia. The E2/T ratio was also higher in boys with gynecomastia (P〈0.005). These data suggest that prolactin, a hormone which may be increased in galactorrhea, is not involved in the development of marked pubertal gynecomastia in boys. The above findings suggest that slightly elevated day-time E2 levels may be involved in the development of female-appearing breasts in pubertal boys.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1076
    Keywords: Acute lymphoblastic leukemia ; Hypergonadotropic hypogonadism ; SHBG-deficiency ; Hyperprolatinaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Five pubertal boys (puberty stage Iv–V) and four prepubertal girls with acute lymphoblastic leukemia were treated with a combination of prednisone, vincristine, daunorubicin and l-asparaginase for remission induction. The hypothalamopituitary-gonadal axis was investigated by measuring basal plasma levels of LH, FSH, and PRL in both groups as well as the response to LHRH/TRH stimulation in pubertal boys before, on day 10, 21, and 28 during induction therapy and 23 days after the induction phase (day 51). Furthermore, the binding capacity of sex-hormone-binding globulin (SHBG), plasma levels of testosterone (T) and estradiol (E2) were monitored as well as the testicular volumes of the boys. Within three weeks of induction chemotherapy, plasma T, E2 and the binding capacity of SHBG decreased in both groups, together with a reduction of testicular volumes in the boys. Concommitantly, basal LH, FSH, and PRL values doubled with a normal gonadotrophin response to LHRH. The PRL response to TRH increased at the end of the induction phase, when chemotherapy with vincristine, daunorubicin and l-asparaginase was terminated, but prednisone treatment was continued for 7 another days. During the subsequent prophylactic irradiation of the central nervous system combined with other antileukemic drugs, all hormonal values including testicular volumes in pubertal boys became normal within a period of 3 weeks. Our data clearly demonstrate that an induction chemotherapy regimen such as that employed by the Berlin protocol leads to a transient castrating effect at the gonadal level and to a transient failure of synthesis of SHBG at the hepatic level. Increased prolactin values as well as an increased response to TRH may be related to a decrease in T indicating the existence of a negative feed-back-loop mechanism between T and PRL.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 135 (1980), S. 103-105 
    ISSN: 1432-1076
    Keywords: Thalassemia ; Blackfan-Diamond anemia ; Hypothalamic dysfunction ; Hyperprolactinemia ; Hypogonadotropic hypogonadism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 13 year old boy with Blackfan-Diamond anemia treated with frequent transfusions was investigated for endocrine abnormalities. Prepubertal plasma LH and FSH values, lack of sleep-related hormone rhythms of the gonadotropins, as well as prepubertal responses of LH and FSH to acute stimulation with LHRH strongly suggests that a hypothalamic-pituitary abnormality is the cause of the hypogonadotropic hypogonadism observed in this patient. As a result of impaired stimulation of the gonads plasma testosterone was prepubertal. A three-to fourfold increase of basal plasma PRL values was found without any signs of a typical sleep-dependent increase. Values obtained ranged between 21 ng/ml and 24 ng/ml (normal range 5–8 ng/ml). A normal response to TRH stimulation was found. These results suggest that hemosiderosis may responsible for the hyperprolactinemia as a result of hypothalamic-pituitary dysfunction. Furthermore, dysfunction is demonstrated by prepubertal responses of LH and FSH to LHRH stimulation.
    Type of Medium: Electronic Resource
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