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  • 2000-2004  (1)
  • 1990-1994  (3)
  • Stallion spermatozoa  (2)
  • kinetics  (2)
  • 1
    ISSN: 1573-5168
    Keywords: fish ; sea raven ; gluconeogensis ; hepatocytes ; redox ; LDH ; isozymes ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have reported very low rates of gluconeogenesis from lactate in sea raven (Hemitripterus americanus) hepatocytes compared to other teleosts studied. This study examines whether hepatic cell redox or lactate dehydrogenase (LDH) characteristics may explain this observation. Sea raven hepatic optimal LDH activities (pyruvate reductase direction) were more than 40 times less compared with rainbow trout liver values (40 vs 1914 μmol·min−1·g−1 protein). The Km(lactate) was 9.24 and 0.86 mM for sea raven and trout hepatic LDH, but the Km(pyruvate) was similar between the two species (0.11 and 0.21 mM, respectively). These results suggested that sea raven liver LDH did not favour lactate use and was more indicative of the mammalian M-isozyme. Gel electrophoresis showed a predominant intermediate isozyme, with a small amount of the M-type LDH. Phosphoenolpyruvate carboxykinase (PEPCK) was localized to the mitochondrial compartment, while there was no apparent mitochondrial glutamate-oxaloacetate transaminase (GOT) activity. No in vitro lactate flux to glucose was found in untreated, 10 mM ethanol-treated, or 3 mM NH4Cl-treated sea raven hepatocytes, although CO2 production from lactate was decreased by ethanol and increased by NH4Cl. These results provide evidence that cell redox does not limit gluconeogenesis from lactate, while low activities and the kinetic characteristics of LDH may partially explain the low lactate gluconeogenesis reported in sea raven hepatocytes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 747-755 
    ISSN: 1572-8943
    Keywords: benzoic acid ; europium complex ; kinetics ; non-isothermal ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition of Eu2(BA)6(bipy)2 (BA=C2H5N– 2, benzoate; bipy=C10H8N2, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method, the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)2/3.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 152-158 
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; Acrosome reaction ; Monoclonal antibody ; Zona-free hamster eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 ± 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona-free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 361-365 
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; lonophore ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vitro fertilizing ability of stallion spermatozoa was assessed using horse follicular oocytes matured in vitro. After collection, stallion spermatozoa were either: 1) washed and incubated in TALP medium with 3 mg/ml bovine serum albumin (BSA) and 10 μg/ml heparin for 4 h, 2) washed and incubated in TALP with 3 mg/ml BSA for 3 h and cultured for a further 1 h with 1 mM caffeine and 5 mM dbcAMP, 3) washed and incubated in TALP medium with 3 mg/ml BSA at pH 7.9-8.2 for 2-4 h, or 4) diluted and incubated in TALP medium with 10 mg/ml BSA and 7.14 μM calcium ionophore A 23187 for 5-10 min followed by washing. After a given pretreatment, suspensions were diluted into B2 medium to a concentration of 5 × 106 sperm/ml and co-incubated with oocytes for 12 h or 24-48 h. In the ionophoretreated group, 18 of 54 oocytes (33%) were fertilized by 12 h, and 11 of 45 (24%) cleaved by 24-48 h. Evidence of fertilization was not found in the oocytes incubated with spermatozoa from other treatment procedures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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