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  • 1
    ISSN: 1432-0428
    Keywords: Keywords Pancreatic islets ; nitric oxide synthase ; haem oxygenase ; imunocytochemistry ; confocal microscopy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. To map the cellular location of inducible and constitutive nitric oxide synthase and haem oxygenase in rat islets to clarify the morphological background to putative nitric oxide and carbon monoxide pathways. Methods. Immunocytochemistry and confocal microscopy. Results. After treatment with endotoxin, immunoreactivity for inducible nitric oxide synthase was expressed in a large number of islet cells, most of which were insulin-immunoreactive beta cells and in single glucagon-immunoreactive and pancreatic polypeptide-immunoreactive cells. Somatostatin-immunoreactive cells lacked immunoreactivity for inducible nitric oxide synthase. In untreated rats, immunoreactivity for constitutive nitric oxide synthase occurred in the majority of insulin-immunoreactive and glucagon-immunoreactive cells, in most pancreatic polypeptide-immunoreactive and somatostatin-immunoreactive cells and in islet nerves. Similarly, immunoreactivity for constitutive haem oxygenase was detected in all four types of islet cells. Endotoxin treatment did not change the pattern of immunoreactivity for constitutive and inducible haem oxygenase. After treatment with alloxan, insulin-immunoreactivity was observed only in single islet cells, being almost devoid of immunoreactivity for constitutive nitric oxide synthase and haem oxygenase. Conclusion/interpretation. In vivo endotoxin-induced expression of inducible nitric oxide synthase in insulin-producing and in scattered glucagon-producing and pancreatic polypeptide-producing cells strengthens previous suggestions of a pathophysiological role for inducible nitric oxide synthase in the development of insulin-dependent diabetes mellitus. The presence of constitutive nitric oxide synthase and haem oxygenase in all four types of islet cells, together with recent functional data of ours support roles for nitric oxide and carbon monoxide as intracellular, paracrine or neurocrine modulators of islet hormone secretion. [Diabetologia (1999) 42: 978–986]
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Okadaic acid (OA) is a frequently used phosphatase inhibitor that by inhibiting dephosphorylation increases the net phosphorylation level in various systems. In the present study OA was used to assess the role of balanced phosphorylation-dephosphorylation reactions for successful regeneration of peripheral nerves. To achieve this, the effects of OA on phosphorylation levels, neurite outgrowth, injury-induced support cell proliferation, and neurofilament stability, respectively, were investigated in the in vitro regenerating, adult frog sciatic sensory nerve. OA at a moderate concentration (20 nM) increased phosphorylation levels and almost completely inhibited the in vitro regeneration in a reversible way. The effect on regeneration was not due to induced neurofilament instability and was only seen when the drug was applied in the outgrowth region. The latter and the absence of effects on support cell proliferation indicate that OA acts locally at the level of newly formed axons. However, the inhibition of regeneration was not a consequence of reduced delivery of proteins by axonal transport, because this process in fact was increased by OA. Altogether, the study suggests that properly balanced phosphorylating-dephosphorylating reactions are critical for regeneration of peripheral nerves.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: PACS: 25.55.Kr 2H-,3He- and 4He-induced charge exchange reactions – 14.20.Gk Baryon resonances with S = 0 – 24.10.Eq Coupled channel and distorted wave models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The inclusive 2(3He,t) reaction has been studied at 2 GeV for energy transfers up to 500 MeV and scattering angles from 0.250 up to 40. Data are well reproduced by a model based on a coupled-channel approach for describing the NN and NΔ systems. The effect of final state interaction is important in the low energy part of the spectra. In the delta region, the cross-section is very sensitive to the effects of Δ-N interaction and ΔN → NN process. The latter has also a large influence well below the pion threshold. The calculation underestimates the experimental cross-section between the quasi-elastic and the delta peaks; this is possibly due to projectile excitation or purely mesonic exchange currents.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5168
    Keywords: thyroid hormones ; equilibrium dialysis ; immersion ; radioimmunoassay ; development ; hypothyroid ; smoltification ; teleost ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thyroid hormones transiently increase during parr-smolt transformation in coho salmon, Oncorhynchus kisutch, and are believed to trigger morphological, physiological, behavioural, and neural changes. The effectiveness of propylthiouracil (PTU) to induce hypothyroidism in smolting coho salmon was determined by immersing coho salmon, Oncorhynchus kisutch, in 30 mg l−1 PTU from May 1, two weeks prior to the consistent annual total thyroxine (TT4) peak in mid-May, until the last sampling date. Plasma was obtained at two sampling dates from control and PTU -treated coho salmon: May 15, during the plasma TT4 peak; and May 26, after the TT4 peak. Radioimmunoassays were used to measure plasma TT4, total triiodothyronine (TT3), free thyroxine (FT4), and salmon growth hormone (sGH). The PTU -treatment inhibited the natural smoltification-related increases in plasma TT4, TT3 and GH levels compared with controls, but PTU-treatment did not affect these hormone levels when they were low. PTU -treatment increased FT4 and decreased TT3 and sGH levels in the May 26 sample. In the May 15 sample, FT4 levels were unaffected by PTU-treatment, whereas TT4 levels were decreased. These data demonstrate the ability of PTU to induce hypothyroidism in salmonids as shown by the decrease in TT4 and TT3. These data demonstrate that PTU treatment by immersion can induce hypothyroidism in salmonids as shown by: (1) the inhibition of the natural increases of TT4 and TT3; (2) the increase in FT4 levels corresponding to the lowered TT3 levels, suggesting an inhibition of thyroxine 5′-monodeiodinase activity. We also show for the first time that PTU treatment can lower plasma GH levels in salmonids. This lowering of plasma GH level is associated with the decrease in TT3 levels and the increase in FT4 levels. The PTU induced lowering in GH levels may contribute to the observed changes in FT4 and TT3, since GH is known to increase thyroxine 5′-monodeiodinase activity.
    Type of Medium: Electronic Resource
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