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  • Life and Medical Sciences  (26)
  • in vitro fertilization  (5)
  • calcium  (4)
  • 1
    ISSN: 1432-1424
    Keywords: calcium ; calmodulin ; absorption ; ileum ; brush-border vesicle ; phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In rabbit ileum, Ca2+/calmodulin (CaM) appears to be involved in physiologically inhibiting the linked NaCl absorptive process, since inhibitors of Ca2+/CaM stimulate linked Na+ and Cl− absorption. The role of Ca2+/CaM-dependent phosphorylation in regulation of the brush-border Na+/H+ antiporter, which is believed to be part of the neutral linked NaCl absorptive process, was studied using purified brush-border membrane vesicles, which contain both the Na+/H+ antiporter and Ca2+/CaM-dependent protein kinase(s) and its phosphoprotein substrates. Rabbit ileal villus cell brush-border membrane vesicles were prepared by Mg precipitation and depleted of ATP. Using a freezethaw technique, the ATP-depleted vesicles were loaded with Ca2+, CaM, ATP and an ATP-regenerating system consisting of creatine kinase and creatine phosphate. The combination of Ca2+/CaM and ATP inhibited Na+/H+ exchange by 45±13%. This effect was specific since Ca2+/CaM and ATP did not alter diffusive Na+ uptake, Na+-dependent glucose entry, or Na+ or glucose equilibrium volumes. The inhibition of the Na+/H+ exchanger by Ca2+/CaM/ATP was due to an effect on theV max and not on theK m for Na+. In the presence of CaM and ATP, Ca2+ caused a concentration-dependent inhibition of Na+ uptake, with an effect 50% of maximum occurring at 120nm. This Ca2+ concentration dependence was similar to the Ca2+ concentration dependence of Ca2+/CaM-dependent phosphorylation of specific proteins in the vesicles. The Ca2+/CaM/ATP-inhibition of Na+/H+ exchange was reversed by W13, a Ca2+/CaM antagonist, but not by a hydrophobic control, W12, or by H-7, a protein kinase C antagonist. we conclude that Ca2+, acting through CaM, regulates ileal brush-border Na+/H+ exchange, and that this may be involved in the regulation of neutral linked NaCl absorption.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of assisted reproduction and genetics 12 (1995), S. 406-412 
    ISSN: 1573-7330
    Keywords: in vitro fertilization ; estradiol ; fertilization rates ; pregnancy rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective Exogenous estradiol (E2) has a well-recognized interceptive action when administered shortly after ovulation. The influence of extremely elevated levels of endogenous E2 on human oocyte fertilization and implantation are unclear. The purpose of this study was to evaluate a potential antinidatory role of extremely high endogenous E2 concentrations on implantation and pregnancy duringin vitro fertilization-embryo transfer (IVF-ET). Methods Twenty-five patients receiving human menopausal gonadotropins (hMG) following midluteal GnRHa administration for IVF-ET, in which the maximal E2 concentration was 〉5000 pg/ml (range 5358–16,344 pg/ml) were studied. Cycle parameters including oocyte and embryo characteristics, fertilization, cleavage, and implantation rates as well as pregnancy outcomes were compared to those of 25 patients treated contemporaneously whose treatment cycles had peak E2 values 〈3500 pg/ml. Patients groups were matched for age, infertility diagnoses, duration of infertility and stimulation protocol. Results Cycles characterized by very high endogenous E2 levels resulted in significantly more oocytes per retrieval (21.4± 1.7 versus 8.4± 0.6;P 〈 0.0001), fewer postmature oocytes (1.6%± 1.0% versus 14%± 5.0%;P 〈 0.03), and a decreased fertilization rate (63%±4.0% versus 73%±3.0%;P 〈 0.04) compared to control cycles. There were no differences in the overall mean morphologic grade or cleavage rates between groups. However, high E2 cycles were associated with a significantly increased implantation rate (14%±4.0% versus 8.0%±4.0%;P 〈 0.01) and pregnancy rate per embryo transfer (62%±16% versus 36%±16%;P 〈 0.01) compared to controls. The incidence of spontaneous abortion did not differ between groups. Conclusions Extremely high endogenous E2 levels do not appear to adversely affect implantation or overall cycle pregnancy rates in IVF-ET cycles. However, impaired fertilization rates in such cycles support a potential adverse effect on oocyte quality.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of assisted reproduction and genetics 11 (1994), S. 33-37 
    ISSN: 1573-7330
    Keywords: epidermal growth factor ; preimplantation embryo development ; in vitro fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose Enhanced embryo maturity and advanced stages of cleavage at the time of embryo transfer are associated with superior pregnancy rates in in vitrofertilization procedures. This study was performed to assess the potential usefulness of epidermal growth factor (EGF) to enhance the development of murine preimplantation embryos cultured in vitro.Two-cell stage mouse embryos were cultured for 72 hr with EGF at concentrations of 0.1 to 100 ng/ml. The percentage of embryos which developed to the expanded and hatching blastocyst stage at 72 hr was determined. Results The percentage of fully expanded and hatching murine blastocysts at 72 hr was significantly higher following incubation with EGF at concentrations of 2 ng/ml (44±4.1%; p〈0.02), 20 ng/ml (41±3.2%; P=0.04), 50 ng/ml (43±2.5%; P〈0.04), and 100 ng/ml (46±3.6%; P=0.001) compared to controls. This effect of enhanced embryonic development by EGF was neutralized by coincubation with 1.0 Μg/ml of anti-EGF antibody. Conclusion EGF at concentrations of 2 to 100 ng/ml significantly enhanced the percentage of expanded and hatching murine blastocysts at 72 hr.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of assisted reproduction and genetics 4 (1987), S. 107-110 
    ISSN: 1573-7330
    Keywords: in vitro fertilization ; human menopausal gonadotropins ; luteinizing hormone release ; estradiol levels ; hypothalamic pituitary axis ; follicle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study demonstrates that luteinizing hormone (LH) release may occur despite sustained elevations of estradiol E2 in women receiving human menopausal gonadotropin. Mean levels of E2 did not correlate with the LH surge, however, the follicle number and a rapid rise in E2 did. Therefore, it appears that the protective influence of inhibitory proteins secreted by multiple follicles can be overridden, allowing spontaneous LH release.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of assisted reproduction and genetics 4 (1987), S. 153-158 
    ISSN: 1573-7330
    Keywords: serum ; fractions ; effects ; in vitro fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To examine the effect of various fractions of human fetal cord serum (HCS) on mouse embryos cultured in vitro, heat-inactivated HCS was separated by ultrafiltration into five distinct fractions: Fractions A, MW〉30,000; B, MW 30,000−10,000; C, MW 10,000−5000; D, MW 5000−1000; and E, MW 〈1000. Seven hundred twentyeight single-cell embryos were cultured in TYH- 280 medium supplemented with 8 mg/ml bovine serum albumin (BSA) and a 20% concentration of Fraction A, B, C, D, or E, whole HCS, or BSA alone. Embryos cultured with Fraction A or E or whole HCS demonstrated a significantly reduced growth rate (P〈0.01), while embryos cultured with Fraction D demonstrated a significantly increased growth rate (P〈0.01). Additionally, 649 singlecell embryos were cultured in medium which was supplemented with 8 mg BSA/ml and a 0, 1,2, or 5% concentration of Fraction A or E. Fraction E displayed toxicity even at a 1% concentration (P〈 0.07), while Fraction A demonstrated growth inhibition at a 5% concentration (P 〈0.05) but increased the hatching rate at a 1% concentration (P 〈 0.01). Finally, 635 single-cell embryos were cultured with four distinct fractions of HCS obtained from a Sephacryl S-200 column: Fractions I, MW 100,000; II, MW 70,000−100,000; III, MW 30,000−70,000; and IV, low molecular weight (〈5000). Fraction I or III significantly reduced the embryo growth rate as seen with Fraction A (P〈0.01) and Fraction II significantly increased only the hatching rate (P〈0.01), while Fraction IV significantly increased the growth rate as seen with Fraction D. In conclusion, HCS contains embryo growth inhibitory properties in the high (〉30,000) and low (〈1000) molecular weight components, while growth promoting factors are found in the 1000−5000 MW fraction. It also seems that there are some factors in the 70,000−100,000 MW fraction which may promote the ability of the embryo to hatch.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-7330
    Keywords: follicular fluid ; follicular proteins ; in vitro fertilization ; oocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study was carried out from in vitro fertilization (IVF) attempts to analyze further the total and specific protein contents of 47 follicular fluids yielding one oocyte. The aim was to find correlations between the follicular concentrations of such proteins and the occurrence of coupled oocyte cleavage. These findings would be used as markers of IVF outcome. Two groups of follicular samples were distinguished: one group with cleavage occurrence (25 cases) and another group without cleavage or even fertilization (22 cases). In the group with cleavage a significantly higher level was observed for six proteins: C3 complement fraction and ceruleoplasmin (P 〈0.02), α-antitrypsin and transferrin (P 〈0.01), and α2-macroglobulin and β2-microglobulin (P 〈0.001). The data are discussed with respect to changes in follicle permeability with advancing maturity.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 38 (1994), S. 142-147 
    ISSN: 1040-452X
    Keywords: Micromanipulation ; Zona pellucida ; DNA repair ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The treatment of male factor-related infertility has been approached with the advent of several methods for microsurgical fertilization, such as the partial dissection of the zona pellucida (PZD) and the injection of sperm into the perivitelline space (PVSI) of oocytes. These techniques are designed to increase sperm-oolemma interaction by circumventing passage of the sperm through the zona pellucida. The present study was performed to evaluate the influence of PZD and PVSI on the in vitro development of mouse embryos by assessing the rate of sister chromatid exchange (SCE). SCE is considered to be a sensitive indirect indicator of DNA lesions due to various conditions. Oocytes were cultured in vitro after PZD or PVSI and then examined for SCE. There was no significant difference in SCE between control and treatment groups of embryos and the values were similar to those reported by Saito et al. (Fertil Steril 41:460-464, 1984). The rate of SCE was low during the first two mitotic cycles, then increased from cycle two to three before declining slightly between the 3rd and 4th cycles of cell division. These data demonstrate that the direct interaction of sperm and oocyte by PZD or PVSI did not have an adverse effect on the development of mouse embryos as assessed by the rate of SCE. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 35 (1993), S. 69-75 
    ISSN: 1040-452X
    Keywords: Amphibian ; Microfilaments ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rhodamine phalloidin (Rph) staining was used to examine the microfilament organization of the Xenopus laevis egg cortex during the early stages of fertilization. Unactivated eggs possessed a cytochalasin B (CR)-insensitive Rph-stained matrix that was reorganized upon egg activation and diminished in the presence of CB. Xenopus laevis sperm caused a temporary local increase in Rph staining on the Xenopus cortex. In CB-treated eggs, the local increases of cortical Rph staining later changed to a Rph-free area. These temporary local increases of cortical Rph staining were also observed when Notophthalmus viridescens sperm fertilized Xenopus and Rana pipiens eggs, and were followed by the appearance of concentric rings of stained and unstained areas. Our data suggest that Xenopus and Notophthalmus sperm have activities that can both organize and disrupt the cortical filamentous actin of the Xenopus egg. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 203 (1995), S. 477-490 
    ISSN: 1058-8388
    Keywords: Thrombospondin ; Development ; Extracellular matrix ; In situ hybridization ; Chondrogenesis ; Osteogenesis ; Cornea ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The thrombospondins are a family of related glycoproteins found in the embryonic extracellular matrix. To date, five members of this family have been identified. Thrombospondin-1 and thrombospondin-2 have similar primary structure, but are expressed in different tissues at different times during development. Thrombospondins-3, -4, and cartilage oligomeric protein belong to a second thrombospondin subgroup in which the carboxyl-half of each molecule is most similar to thrombospondin-1 and -2. Here, we report the cloning and sequencing of a novel probe to avian thrombospondin-4. We have used this probe to determine the origins of thrombospondin-4 in the chick embryo by in situ hybridization. Thrombospondin-4 transcripts first appear in the mesenchyme surrounding bone anlage coinciding with the initial stages of osteogenesis. The expression in osteogenic tissues is transient: thrombospondin-4 mRNAs are not seen in the osteoblasts of bone collars in developing long bones. This pattern is distinct from avian thrombospondin-2, which is expressed in perichondrium and embryonic fibrous connective tissues. Our observations indicate that connective tissues are the principal site of thrombospondin-4 expression in the chick. The diverse origins of different thrombospondin gene family members imply distinctive roles for these proteins related to the growth and differentiation of cartilage, tendons, and bone. ©1995 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 51 (1931), S. 527-543 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A vacuome (‘Golgi apparatus’) consisting of small globular inclusions has been demonstrated in Chlamydomonas sp. These inclusions may be seen in the living, unstained organism; they are stainable vitally with neutral red; they have been stained vitally with neutral red and then blackened with osmic vapor under direct observation, and they have been impregnated by osmic and silver methods without previous treatment with neutral red.The reaction of these inclusions to the iodin test for starch suggests that they may play some rǒle, possibly one of storage, in the cycle of starch metabolism.
    Additional Material: 2 Ill.
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