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  • 1990-1994  (280)
  • 1910-1914
  • 1991  (280)
  • Life and Medical Sciences  (280)
  • 1
    Electronic Resource
    Electronic Resource
    The effects of α-amanitin and cycloheximide on nuclear progression, protein synthesis, and phosphorylation during bovine oocyte maturation in vitro (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 28 (1991), S. 249-254 
    Details
    ISSN: 1040-452X
    Keywords: Cow ; In vitro maturation ; Inhibitors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine cumulus oocyte complexes were cultured for various periods and either denuded and orcein stained or radiolabeled with 35S-methionine or 32P-orthophosphate. Specific inhibitors were added to the culture medium to investigate mRNA and protein synthesis requirements for both nuclear and cytoplasmic changes during maturation in vitro. Inhibition of mRNA synthesis by α-amanitin during the first 2 h of culture prevented the phosphorylation of some specific proteins preceding GVBD and decreased the occurrence of GVBD from 97% to 27%. In addition, in oocytes that had undergone GVBD, only part of the changes in protein synthesis after GVBD were observed. Addition of α-amanitin after 3 h of culture had no effect on meiotic maturation. When cumulus oocyte complexes were cultured in the presence of cycloheximide, the phosphorylation of specific proteins was also blocked and only 5% of the oocytes underwent GVBD. Addition of cycloheximide after 4, 6, or 8 h of culture resulted in an increasing percentage of GVBD, but the oocytes became arrested in metaphase I. When cycloheximide was added from 12 h of culture onwards, nuclear progression to metaphase II was increasingly restored.It is concluded that after the onset of culture, both mRNA and protein synthesis are necessary for the phosphorylation of specific proteins and for GVBD. Further-more, transcription during the first hours of culture is needed for the synthesis of new proteins after GVBD.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080280306
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  • 2
    Electronic Resource
    Electronic Resource
    Protein synthesis and phosphorylation patterns of bovine oocytes maturing in vivo (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 29 (1991), S. 271-275 
    Details
    ISSN: 1040-452X
    Keywords: Cow ; Maturation ; Oocyte ; Protein phosphorylation ; Superovulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To investigate protein synthesis and phosphorylation during bovine oocyte maturation in vivo, oocytes were collected at consecutive times after the preovulatory luteinizing hormone (LH) peak. Therefore, heifers treated for superovulation were ovariectomized between 3 and 20 h after the maximum of the LH peak. Subsequently, cumulus-enclosed oocytes, selected from nonatretic follicles 〉10 mm, were radiolabeled with 35S-methionine or 32P-orthophosphate for 3 h and individually prepared for gel electrophoresis. Changes in the protein synthesis patterns were observed coinciding with germinal vesicle breakdown (GVBD). No changes were detected during the ensuing maturation period or coinciding with the extrusion of the first polar body. In addition, the protein phosphorylation patterns exhibited striking differences around GVBD. In particular, a phosphoprotein band of 19 kDa and the two heavily phosphorylated proteins with apparent molecular weights between 50 and 60 kDa were present in patterns of oocytes in the germinal vesicle stage. The results are discussed in relation to previous data obtained during maturation in vitro.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080290309
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of age on nuclear bodies and nuclear volume in pituicytes of the rat neurohypophysis (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 230 (1991), S. 319-324 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study has analyzed age-related changes in the nuclear organization of pituicytes of the rat. The cytological study of the cell nucleus and the quantitative analysis of nuclear bodies (NBs) were performed on ultrathin sections. Nuclear diameter, perimeter, and area were measured on semithin sections, and nuclear volume was estimated from these data. The nucleolus was mainly composed of a few large fibrillar centers with their associated dense fibrillar component, whereas the granular component tended to form large masses at the nucleolar periphery. The most frequent configuration of NBs was a globular inclusion composed of a fibrillar capsule with a core that contained a few electron-dense granules. Intranuclear glycogen was detected on rare occasions and only in old rats. The proportion of nuclear sections containing NBs increased significantly from 1.5% in 3-month-old rats to 8.6% in 18-month-old rats. A significant increase in the nuclear volume was detected in older rats with respect to the younger ones (157±69 vs. 98±43 μm3, mean ±S.D.). Our results suggest an age-related activation of nuclear metabolism in pituicytes resulting in a nuclear expansion and an increase in the frequency of appearance of NBs. This activation might be a reactive cellular event induced by the degenerative changes in neurosecretory nerve endings naturally occurring in older animals.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092300304
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  • 4
    Electronic Resource
    Electronic Resource
    An immunocytochemical study of cutaneous innervation and the distribution of neuropeptides and protein gene product 9.5 in man and commonly employed laboratory animals (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 191 (1991), S. 369-383 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cutaneous nerves of rat, cat, guinea pig, pig, and man were studied by immunocytochemistry to compare the staining potency of general neural markers and to investigate the density of nerves containing peptides. Antiserum to protein gene product 9.5 (PGP 9.5) stained more nerves than antisera to neurofilaments, neuronspecific enolase (NSE), and synaptophysin or histochemistry for acetylcholinesterase (AChE). Peptidergic axons showed species variation in density of distribution and were most abundant in pig and fewest in man. However, the specific peptides in nerves innervating the various structures were consistent between species. Nerve fibers immunoreactive for calcitonin gene-related peptide (CGRP) and/or vasoactive intestinal polypeptide (VIP) predominated in all the species; those immunoreactive to tachykinins (substance P and neurokinin A [NKA]) and neuropeptide tyrosine (NPY) were less abundant. Neonatal capsaicin, at the doses employed in this study, destroyed approximately 70% of CGRP- and tachykinin-immunoreactive sensory axons; whereas 6-hydroxydopamine (6-OHDA) at the doses employed resulted in a complete loss of NPY and tyrosine hydroxylase (TH) immunoreactivity without affecting VIP, CGRP, and tachykinins.Thus, this study confirms that antiserum to PGP 9.5 is the most suitable and practical marker for the demonstration of cutaneous nerves. Species differences exist in the density of peptidergic innervation, but apparently not for specific peptides. Not all sensory axons immunoreactive for CGRP and substance P/NKA are capsaicin-sensitive. However, all sympathetic TH- and NPY- immunoreactive axons are totally responsive to 6-OHDA; but no change was seen in VIP-immunoreactive axons, suggesting some demarcation of cutaneous adrenergic and cholinergic sympathetic fibers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001910404
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  • 5
    Electronic Resource
    Electronic Resource
    Modulation of responsiveness to cAMP stimulating agonists by phorbol ester in fetal rat osteoblasts (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 147 (1991), S. 87-92 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We studied the effect of activation of protein kinase C (PKC) by a phorbol ester on cAMP accumulation in fetal rat osteoblasts. Activation of PKC by phorbol 12-myristate 13-acetate (PMA) caused a potentiation of cAMP accumulation induced by parathyroid hormone (PTH), forskolin, and cholera toxin. The results suggest that the potentiating effect of PMA on PTH-induced cAMP accumulation was not due to an effect on the PTH-receptor nor to an effect on cAMP degradation, as the effect of PMA persisted in the presence of a phosphodiesterase inhibitor. Pretreatment of the cells with pertussis toxin did not prevent the action of PMA, indicating that PMA does not act via the inhibitory G-protein. PMA had a biphasic effect on prostaglandin E2 (PGE2)-induced cAMP accumulation; i.e., at concentrations ≥ 10-6 M, PMA potentiated the PGE2-induced cAMP response but PMA attenuated cAMP accumulation induced by concentrations of PGE2 ≤ 5.10-7 M. From our data we conclude that PKC can interact with a stimulated cAMP pathway in a stimulatory and inhibitory manner. Potentiation of cAMP accumulation is probably due to modification of the adenylate cyclase complex, whereas attenuation of stimulated cAMP accumulation appears to be due to an effect on a different site of the cAMP generating pathway, which may be specific to PGE2-induced cAMP accumulation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041470112
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  • 6
    Electronic Resource
    Electronic Resource
    Poly(ADP-ribosylation) of atypical CS histone variants is required for the progression of S phase in early embryos of sea urchins (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 46 (1991), S. 234-241 
    Details
    ISSN: 0730-2312
    Keywords: ADP-ribosylation ; CS histone variants ; cell cycle ; sea urchin zygotes ; 3 aminobenzamide ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The patterns of poly(ADP-ribosylation) in vivo of CS (cleavage stage) histone variants were compared in sea urchin zygotes at the entrance and the exit of S1 and S2 in the initial developmental cell cycles. This post-translational modification was detected by Western immunoblots with rabbit sera anti-poly(ADP-ribose) that was principally reactive against ADP-ribose polymers and slightly against ADP-ribose oligomers. The effect of 3 aminobenzamide (3-ABA), an inhibitor of the poly(ADP-ribose) synthetase, on S phase progression was determined in vivo by measuring the incorporation of 3H thymidine into DNA. The results obtained indicate that the CS histone variants are poly(ADP-ribosylated) in a cell cycle dependent manner. A significantly positive reaction of several CS variants with sera anti-poly(ADP-ribose) was found at the entrance into S phase, which decreases after its completion. The incubation of zygotes in 3-ABA inhibited the poly(ADP-ribosylation) of CS variants and prevented both the progression of the first S phase and the first cleavage division. These observations suggest that the poly(ADP-ribosylation) of atypical CS histone variants is relevant for initiation of sea urchin development and is required for embryonic DNA replication.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240460306
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  • 7
    Electronic Resource
    Electronic Resource
    Extraspinal course of the fifth lumbar spinal nerve: An update of its topographical relationships (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 4 (1991), S. 319-326 
    Details
    ISSN: 0897-3806
    Keywords: lumbosacral junction ; ventral rami ; dorsal rami ; ligaments ; osteoligamentous tunnels ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fifth lumbar spinal nerve traverses a highly mobile transitional junction of the vertebral column. Evidence suggests that it is often implicated in the etiology of low-back pain, notably in entrapment syndromes. There appears to be a high incidence of unsuccessful attempts at surgical decompression in cases of suspected entrapment of the nerve, suggesting that perhaps the anatomical information on the topography of the nerve is incomplete. The present study examined the course and relations of the fifth lumbar spinal nerve by gross dissection of human cadaveric material. The results showed that the nerve and its subdivisions follow a complex, tortuous course as they cross the lumbosacral junction. The trunk and ventral and dorsal rami are all related to strong ligaments that are thought to be protective. The nearness of these nerves to ligaments in such an area of high mobility, however, predisposes them to impingement or entrapment in the event of joint or ligamentous pathology. It is suggested therefore that investigations of spondylogenic low-back pain should include a detailed evaluation of the status of all parts of the fifth lumbar spinal nerve as they traverse their individual osteoligamentous compartments.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ca.980040502
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  • 8
    Electronic Resource
    Electronic Resource
    Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 12 (1991), S. 47-56 
    Details
    ISSN: 0197-8462
    Keywords: pulsed microwaves ; amplitude modulation ; in vivo ; immune response ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Irradiation by pulsed microwaves (9.4 GHz, 1 μs pulses at 1,000/s), both with and without concurrent amplitude modulation (AM) by a sinusoid at discrete frequencies between 14 and 41 MHz, was assessed for effects on the immune system of Balb/C mice. The mice were immunized either by sheep red blood cells (SRBC) or by glutaric-anhydride conjugated bovine serum albumin (GA-BSA), then exposed to the microwaves at a low rms power density (30 μW/cm2; whole-body-averaged SAR ∼ 0.015 W/kg). Sham exposure or microwave irradiation took place during each of five contiguous days, 10 h/day. The antibody response was evaluated by the plaque-forming cell assay (SRBC experiment) or by the titration of IgM and IgG antibodies (GA-BSA experiment). In the absence of AM, the pulsed field did not greatly alter immune responsiveness. In contrast, exposure to the field under the combined-modulation condition resulted in significant, AM-frequency-dependent augmentation or weakening of immune responses.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250120107
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  • 9
    Electronic Resource
    Electronic Resource
    Collagen type conservation during metamorphic repatterning of the dermal fibers in salamanders (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 208 (1991), S. 99-107 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The orientation of the fibers in the dermis of the tiger salamander, Ambystoma tigrinum, undergoes a dramatic repatterning at metamorphosis. The pre-metamorphic, larval dermis is a tight layer composed of crossed fibers that wind helically around the trunk. This condition is retained by neotenic adults which do not undergo metamorphosis. In contrast, the metamorphosed adult dermis consists of a superficial, loose network of fibers invested with large multicellular glands - -the stratum spongiosum - and a deeper tight layer of fibers - the stratum densum. However, unlike the crossed fibers of the pre-metamorphic dermis, there is no preferred orientation to the fibers in either layer of the post-metamorphic dermis.In order to evaluate whether these two distinctly different fiber patterns are constructed from biochemically similar fibers, the collagen types present in the pre- and post-metamorphic dermis were determined using SDS-polyacrylamide gel electrophoresis. Type I collagen is the predominant collagen of the dermis and the same major collagen types are present for all individuals, whether preor post-metamorphic. Thus, the major types of collagen that compose the dermal fibers do not change during metamorphic repatterning of the dermis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052080105
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  • 10
    Electronic Resource
    Electronic Resource
    Acid phosphatase activity in mature secretory granules of the salivary gland of Bradysia hygida (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 208 (1991), S. 247-255 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It is uncommon to find acid phosphatase activity in mature secretory granules. This paper demonstrates by light and electron microscope cytochemistry an acid phosphatase in mature secretory granules in the cells of one region of the salivary gland of Bradysia hygida (Diptera, Sciaridae). These secretory granules increase in number during larval development up to the beginning of the pre-pupal period when they undergo massive exocytosis. Biochemical assays show that upon exocytosis of the majority of the granules the total acid phosphatase activity in the granular gland region drops to 10% of the maximum reached before exocytosis. During and after exocytosis, two other acid phosphatases, eletrophoretically different and much weaker in activity, become increasingly detectable in all gland regions. At the same time, in whole mount preparations, numerous tiny acid phosphatase-positive granules (probably secondary lysosomes) become evident in all major cell types of the salivary gland. These results indicate that the S2 region of the salivary gland has mature secretory granules containing an acid phosphatase destined for exocytosis which is different in molecular properties from other acid phosphatases (likely lysosomal) made by the gland.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052080302
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