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  • Anguilla australis  (1)
  • Artemisinin  (1)
  • 1
    ISSN: 1573-5168
    Schlagwort(e): spawning migration ; spermatogenesis ; freshwater eels (Teleostei) ; Anguilla dieffenbachii ; Anguilla australis ; male ; histology ; steroid profiles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Immature and maturing male New Zealand freshwater eels, the shortfinned Anguilla australis and the longfinned A. dieffenbachii, were caught from the wild to obtain data on the natural reproductive physiology of these fish. Plasma samples were analysed for steroid hormones by radioimmunoassay and values related to the developmental stage of the testes. Our histological observations on testes largely confirmed those reported previously. Thus, the gonad of non-migrating eels often appeared undifferentiated or poorly developed, containing only type A or early type B spermatogonia. In contrast, the testes of migrating shortfins were in early spermatogenesis as evidenced by the presence of late type B spermatogonia. Similarly, early spermatogenic stages were common in migratory longfins, but eels in midspermatogenesis (all germ cell stages present) were also encountered. Unlike a previous study, patches of testicular regression were commonly seen in migrants of both species. Levels of several androgens, androstenedione (AD), testosterone and 11-ketotestosterone (KT), were elevated in migrants compared to non-migrants. AD was higher in early to midspermatogenic A. dieffenbachii (0.63 ng ml−1) than in A. australis (0.25 ng ml−1) in the spermatogonial proliferation stage, while the inverse was observed for KT (27.78 ng ml−1 and 50.52 ng ml−1, respectively). Levels of 17,20β-dihydroxy-4-pregnen-3-one were nearly undetectable (less than 0.12 ng ml−1) in all animals. Plasma 17-hydroxyprogesterone concentrations in fyke-caught eels were elevated to a greater extent in non-migrants (up to 1.92 ng ml−1) than in migrants (around 0.5 ng ml−1), and correlated well with levels of cortisol in all groups. Histological results are compared to previous studies and the presence of regression in the testes is discussed. In addition, the role of steroid hormones, in particular AD and KT, in reproduction and stress is considered.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0568
    Schlagwort(e): Key words Lateral reticular nuclei ; Paramedian reticular nuclei ; Perihypoglossal nuclei ; Malaria ; Arteether ; Artemisinin ; Neurotoxicity ; Rhesus monkey ; Antimalarial drugs ; Cerebral malaria ; Macaca mulatta ; Plasmodium falciparum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Malaria poses a threat across several continents: Eurasia (Asia and parts of Eastern Europe), Africa, Central and South America. Bradley (1991) estimates human exposure at 2,073,000,000 with infection rates at 270,000,000, illnesses at 110,000,000, and deaths at 1,000,000. Significant mortality rates are attributed to infection by the parasite Plasmodium falciparum, with an estimated 90% among African children. A worldwide effort is ongoing to chemically and pharmacologically characterize a class of artemisinin compounds that might be promising antimalarial drugs. The U.S. Army is studying the efficacy and toxicity of several artemisinin semi-synthetic compounds: arteether, artemether, artelinic acid, and artesunate. The World Health Organization and the U.S. Army selected arteether for drug development and possible use in the emergency therapy of acute, severe malaria. Male Rhesus monkeys (Macaca mulatta) were administered different daily doses of arteether, or the vehicle alone (sesame oil), for a period of either 14 days, or 7 days. Neuropathological lesions were found in 14-day arteether treated monkeys in the precerebellar nuclei of the medulla oblongata, namely: (1) the lateral reticular nuclei (subnuclei magnocellularis, parvicellularis, and subtrigeminalis), (2) the paramedian reticular nuclei (subnuclei accessorius, dorsalis, and ventralis), and the perihypoglossal nuclei (n. intercalatus of Staderini, n. of Roller, and n. prepositus hypoglossi). The data demonstrate that the simian medullary precerebellar nuclei have a high degree of vulnerability when arteether is given for 14 days at dose levels between 8 mg/kg per day and 24 mg/kg per day. The neurological consequences of this treatment regimen could profoundly impair posture, gait, and autonomic regulation, while eye movement disorders might also be anticipated.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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