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  • 1
    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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  • 2
    ISSN: 1573-6830
    Keywords: adenylate cyclase ; catecholamines ; adrenergic receptors ; cyclic AMP ; phosphodiesterase ; neurotransmission ; calcium ; brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The calcium-dependent K+-evoked release of [3H]norepinephrine from guinea pig cerebral cortical vesicular preparations is inhibited by norepinephrine, clonidine, and epinephrine. Isoproterenol has no effect and phentolamine prevents the inhibition by norepinephrine. The results indicate that anα-adrenergic receptor mediates an inhibitory input to the calcium-dependent release process. The inhibition by norepinephrine is prevented by high concentrations (3.0 mM) of calcium ions. 2. A cyclic AMP phosphodiesterase inhibitor, ZK 62771, slightly elevates [3H]cyclic AMP levels in the guinea pig cerebral cortical preparation and potentiates the marked elevation of [3H]cyclic AMP elicited by the adenylate cyclase activator, forskolin. 3. Neither ZK 62771 nor forskolin alone has significant effects on K+-evoked release of [3H]norepinephrine from the cerebral cortical vesicular preparation; however, a combination of ZK 62771 and forskolin inhibits K+-evoked release by as much as 60%. The inhibition is reversed by high concentrations (2.0 mM) of calcium ions. The results suggest that a marked accumulation of cyclic AMP elicited via both activation of adenylate cyclase and inhibition of phosphodiesterase can be inhibitory to neurotransmitter release from central synaptic terminals.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 2 (1982), S. 193-204 
    ISSN: 1573-6830
    Keywords: adenosine ; catecholamines ; neurotransmission ; calcium ; brain ; striatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Adenosine analogues inhibit calcium-dependent K+-evoked release of [3H]norepinephrine from guinea pig cerebral cortical and hippocampal vesicular preparations. Inhibition requires high concentrations (100µM) of the adenosine analogues and is abolished in the presence of high concentrations (2 mM) of calcium ions. The inhibitory effect of 2-chloroadenosine is blocked by theophylline. The structure activity profile (N 6-d-phenylisopropyladenosine ≥N 6-l-phenylisopropyladenosine ≥ 2-chloroadenosine 〉N 6-cyclohexyladenosine, adenosine 5′-cyclopropylcar-boxamide) is not that expected of either A1 (high-affinity) or A2 (low-affinity) adenosine receptors. 2. Calcium-dependent K+-evoked release of [3H]dopamine from guinea pig striatal vesicular preparations is inhibited by apomorphine. However, only 2-chloroadenoine causes an inhibition of K+-evoked release of [3H]dopamine. Other adenosine analogues such asd- andl-phenylisopropyladenosine and adenosine 5′-cyclopropylcar-boxamide cause a facilitation of K+-evoked release. The facilitation is abolished or reduced in the presence of high concentrations (2 mM) of calcium ions. The sites of action of adenosine analogues do not appear to have structural requirements identical to those expected of A1 (high-affinity) or A2 (low-affinity) adenosine receptors. 3. The results indicate that adenosine analogues can have either inhibitory or facilitory effects on K+-evoked release of catecholamines from central synaptic terminals.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 2 (1982), S. 205-213 
    ISSN: 1573-6830
    Keywords: calcium ; catecholamines ; neurotransmission ; brain ; striatum ; calcium antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The calcium antagonists D-600 (1–10µM) and diltiazem (10–25µM) inhibit K+-evoked release of [3H]norepinephrine from guinea pig cerebral cortical vesicular preparations. The inhibition of release is partially reversed by increasing concentrations of calcium to 2 mM. Diltiazem at 100µM has no effect on K+-evoked release of [3H]norepinephrine at 0.15 mM calcium but does inhibit release at 2.0 mM calcium. 2. The calcium antagonist nifedipine and dantrolene, an agent purported to antagonize release of calcium from intracellular storage sites, have no effect on K+-evoked release of [3H]norepinephrine. 3. The calcium antagonists D-600 (1µM) and diltiazem (10µM) inhibit K+-evoked release of [3H]dopamine from guinea pig striatal vesicular preparations. Higher concentrations of drug, namely, 10µM for D-600 and 100µM for diltiazem, cause a potentiation rather than an inhibition of K+-evoked release. The potentiation is reduced in magnitude upon raising the extracellular calcium to 2.0 mM. Indeed, 10µM D-600 then inhibits K+-evoked release of [3H]dopamine. 4. The results indicate that putative calcium antagonists can have both inhibitory and facilitory effects on calcium-dependent K+-evoked release of catecholamines from central synaptic endings. Furthermore, certain peripheral calcium antagonists such as nifedipine and dantrolene may prove ineffective in central systems.
    Type of Medium: Electronic Resource
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  • 5
    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.
    Type of Medium: Electronic Resource
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  • 6
    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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  • 7
    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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  • 8
    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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