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  • 1
    ISSN: 1432-0428
    Keywords: Islet of Langerhans ; insulin secretion ; nitric oxide ; cyclic guanosine monophosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The involvement of nitric oxide as an intracellular messenger in the control of insulin secretion from pancreatic Beta cells was studied in rat islets of Langerhans by measuring: (i) nitric oxide generation in response to physiological insulin secretagogues; (ii) the effects of inhibitors of nitric oxide synthesis on insulin secretory responses to physiological secretagogues, and on insulin synthesis; (iii) changes in islet cyclic guanosine monophosphate in response to secretagogues; (iv) the effects of exogenous cyclic guanosine monophosphate and dibutyryl cyclic guanosine monophosphate on insulin secretion from electrically permeabilised islets and from intact islets, respectively. These studies produced no evidence that nitric oxide generation is required for the initiation of insulin secretion by common secretagogues. However, the results of our experiments suggest that the generation of nitric oxide may be involved in long-term, glucose-dependent increases in cyclic guanosine monophosphate content of islet cells, although the physiological relevance of these changes requires further investigation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta diabetologica 30 (1993), S. 99-104 
    ISSN: 1432-5233
    Keywords: Insulin synthesis ; Islet of Langerhans ; Northern blotting ; Phorbol ester ; Protein kinase C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Activation of protein kinase C (PKC) by the phorbol ester 4β-phorbol myristate acetate (4β-PMA) stimulated (pro)insulin biosynthesis in collagenase-isolated rat islets of Langerhans, as assessed by measuring the incorporation of [35S]cysteine into proinsulin and insulin after fractionation by high performance liquid chromatography. The stimulatory effects of 4β-PMA were observed at a substimulatory concentration of glucose (2 mM) but were not additive to the stimulatory effects of 20 mM glucose on insulin biosynthesis. Prolonged exposure to 4β-PMA caused a marked down-regulation of PKC activity in islets. PKC-depleted islets showed a much reduced biosynthetic response to 20 mM glucose, but this was caused, at least in part, by an enhanced basal rate of (pro)insulin synthesis. These elevations in the basal rate of insulin synthesis were not secondary to an inerease in the amount of preproinsulin mRNA in PKC-depleted islets since Northern blot analysis showed that prolonged exposure to 4β-PMA, and the subsequent loss of PKC activity, did not detectably alter basal levels of preproinsulin mRNA. These results suggest that the activation of PKC stimulates (pro)insulin synthesis in rat islets by enhancing translation of existing preproinsulin mRNA, and that this may play some part in the biosynthetic responses of β-cells to glucose.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-5233
    Keywords: Islet of Langerhans ; Insulin secretion ; Protein phosphorylation ; Protein kinase C ; Protein kinase A ; Inhibitory peptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have used electrically permeabilised rat islets of Langerhans to investigate the role of protein phosphorylation in the regulation of insulin secretion using pseudosubstrate inhibitory peptides for cyclic AMP-dependent protein kinase (PKA) and for protein kinase C (PKC). The protein kinase inhibitor (PKI) peptide, PKI(6–22), completely inhibited the effects of cyclic AMP on islet PKA activity in vitro, on endogenous protein phosphorylation and on insulin secretion. This peptide had no significant effect on islet PKC activity in vitro, on CA2+-induced protein phosphorylation and on secretory responses to Ca2+ or to the PKC activator, 4β-phorbol myristate acetate (PMA). The PKC pseudosubstrate inhibitory peptide, PKC(19–36), caused a marked inhibition of islet PKC activity in vitro and inhibite PMA-induced insulin secretion without affecting secretory responses to cyclic AMP and Ca2+. These results demonstrate that PKA-and PKC-induced protein phosphorylation is obligatory for cyclic AMP-and PMA-stimulated insulin secretion, respectively, and suggest that there is little “crosstalk” between the response elements of the secretory pathways to the different, second messengers, at least after the generation of the messengers within the β-cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-3725
    Keywords: 23.20.Nx ; 29.30.Dn ; 23.20.Lv ; 21.10.Re ; 25.70.Jj ; 27.70.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using conversion electron and γ-ray spectroscopy combined with a recoil gating method, excited states in 188Pb have been investigated. Further evidence for two excited low-lying 0+ states has been found leading to an interpretation as a multiple shape coexistence in 188Pb.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-3725
    Keywords: 23.20.Nx ; 29.30.Dn ; 23.20.Lv ; 21.10.Re ; 25.70.Jj ; 27.70.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using conversion electron and γ-ray spectroscopy combined with a recoil gating method, excited states in 188Pb have been investigated. Further evidence for two excited low-lying 0+ states has been found leading to an interpretation as a multiple shape coexistence in 188Pb.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 203 (1982), S. 293-299 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This paper describes an extensive study of the growth of ossification centers in limb long bones of the human fetus from 8 to 26 weeks of conceptual age. Longitudinal measurements were made of the femur, tibia, fibula, humerus, radius, and ulna. Comparisons were made between bones on the left and right sides of the body and between the sexes. Standards are presented for the growth of these centers. They compare well with previous studies, any differences being accounted for by different methods of aging and measurement.A complicated picture of growth of the two sides of the fetal body is presented. Growth of the humerus, tibia, and fibula appears to be dominant on the left side of the body while growth in the femur is dominant on the right. At present, no explanation is available, but it is possible that factors such as manual dominance may be related. Evidence also is presented which suggests that the female fetus is in advance of the male in terms of ossification but only after 21 weeks gestation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 204 (1982), S. 265-270 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Only a few studies have concerned themselves with the development of the fetal vertebral column, and this paper attempts to extend the literature. Standards are presented for the growth in width of the human vertebral column between 10 and 26 weeks of conceptual age. The growth patterns show that cervical and lumbar enlargements are not present at 8 weeks but develop slowly and become clearly present at 26 weeks. The growth equations also show that groups of vertebrae have their own growth patterns, indicating that the vertebral column could be separated into five groups: C1-C5, C6-C7, T1-T12, L1-S1, and S2-S5. Furthermore, comparisons with growth patterns available for growth in length from other studies reveal that some vertebrae appear to develop in one dimension independently of another.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 208 (1984), S. 265-270 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Variations of the vertebral column were considered to be those deviations from the norm which were still compatible with normal life and not pathological. The incidence of these variations is described as seen radiographically in a group of normal human fetuses.Ossification centers for the costal processes of cervical vertebra 7 were found to be common (19%), being present in approximately one-fifth of the total number of fetuses studied. They were mostly present as bilateral centers (15%), but because of the cross-sectional nature of the study, it could not be determined whether these centers would have developed into actual cervical ribs. Far less common were the presence of lumbar ribs (1%). Ossification of the vertebral centra was found to be confusing with no clearly defined pattern being evident. In particular, there was a suggestion that some of the vertebral centra might well develop at least initially from bilateral centers. There was also evidence that the vertebral body was the product of four centers and this was supported by other literature. No variations were found which suggested that the vertebra develops from two somite levels, and this appears to be in conflict with the commonly accepted resegmentation theory.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 41 (1995), S. 513-520 
    ISSN: 1040-452X
    Keywords: Aerosome reaction ; Calcium binding ; Membrane fusion ; Pyroantimonate ; Vesiculation ; Ram spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Calcium was identified by a pyroantimonate-osmium fixation technique in ram spermatozoa undergoing a spontaneous acrosome reaction induced by incubation of diluted semen at 39°C. Intracellular calcium was only detected in diluted spermatozoa and increased in amount and distribution over 4 hr At 4 hr, the majority of the spermatozoa displayed ultrastructural evidence of an acrosome reaction. Calcium was initially evident on the outer acrosomal membrane in multiparticulate clusters, which were seen to be located on scalloped crests of acrosomal membrane as fusion developed; it was also located in the region of the acrosomal ridge beneath the outer acrosomal membrane. Vesiculation commenced just anterior to the equatorial segment and proceeded anteriorly. As vesiculation advanced, calcium particles became associated with the periphery of the vesicles attached in the region of the fusion between the two membranes, but were never seen inside the vesicles. The equatorial segment was not labelled until much later in the reaction, at which time calcium particles were also evident on the nuclear membrane; vesiculation of the equatorial segment was also noted at this time.Dense labelling of the postacrosomal dense lamina was seen in all incubated spermatozoa. At the anterior margin of this structure the labelling was seen to be in a “sawtooth” arrangement. The disposition of the calcium both temporally and spatially is discussed in relation to its possible mechanisms in bringing about membrane fusion. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 73 (1969), S. 37-42 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of temperature on intracellular ATP levels in cells of the ascitic Hepatoma 129 has been determined using an UV-enzymic method. ATP levels are found to vary inversely with temperature over the range (4°-37°C) studied, and this variation is found to be reversible. An indication of a possible direct correlation of ADP level with temperature was also obtained.A correlation is deduced between rise in intracellular ATP level and decrease in cytoplasmic viscosity, both from the present results, and from similar effects recently reported by Landau ('61) for increase in pressure.The significance of these observations is discussed with reference to the model for cytoplasmic viscosity proposed by Marsland ('56) and the wider biological significance of this effect is explored.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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