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  • 1
    ISSN: 1432-0428
    Keywords: Salt Bush ; Atriplex Ash ; Mannoheptulose ; Sand Rats ; Diabetogenesis ; Alloxan-diabetic Rats ; Glucose Tolerance Test ; R. Q.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le diabète a été provoqué chez le rat des sables par une augmentation de la prise de calories. Le développement du diabète a été marqué par l'élévation progressive des taux d'hyperglycémie dans le test de tolérance au glucose, par l'apparition de cataracte, de glycosurie et d'obésité. La cétonurie n'a jamais été constatée. Les rats des sables diabétiques ont un BMR légèrement élevé et un RQ de 1 approximativement. Ils répondent au D-mannoheptulose par une hyperglycémie, mais non par un RQ réduit. La cendre de l'AtriplexHalimus ne réduit pas l'hyperglycémie due au test de tolérance au glucose alors qu'elle la réduit chez les rats alloxanisés. Les rats alloxanisés répondent au D-mannoheptulose, il se peut que la réponse au D-mannoheptulose soit sous la dépendance d'une sécrétion de glucagon.
    Abstract: Zusammenfassung Bei Sandratten wurde ein Diabetes durch erhöhte Kalorienaufnahme in der Nahrung erzielt. Der Entwicklung des Diabetes folgte eine fortschreitende Erhöhung des Blutzuckerspiegels beim Glucosetoleranztest, sowie Glykosurie, Fettsucht und Katarakt. Eine Ketonurie wurde niemals beobachtet. Die diabetischen Ratten hatten einen leichten erhöhten Grundumsatz und einen respiratorischen Quotienten von etwa 1,0. Auf D-Mannoheptulose reagierten sie mit Hyperglykämie, nicht aber mit einer Erniedrigung des respiratorischen Quotient. Die Gabe von Asche von Atriplex halimus (Staudenmelde) setzte den hyperglykämischen Glucosetoleranztest nicht herab, wie es bei alloxan-diabetischen Ratten beobachtet wurde. Alloxan-diabetische Ratten behalten ihre Reaktionsfähigkeit auf D-Mannoheptulose; es wird vermutet, daß diese Reaktionen auf D-Mannoheptulose von einer Glucagon-Sekretion abhängig ist.
    Notes: Summary Diabetes was induced in sand rats by increasing the dietary intake of calories. The development of diabetes was followed by progressively greater hyper-glycaemic levels in the glucose tolerance test and the appearance of cataract, glucosuria and obesity. Ketonuria was never seen. Diabetic sand rats had a slightly elevated BMR and an RQ of approximately 1. They responded to D-mannoheptulose with hyperglycaemia but not with reduced RQ.Atriplex halimus ash did not reduce the hyperglycaemic response to glucose, though it has been reported to do so in alloxanized rats. Alloxanized rats were shown to retain responsiveness to D-mannoheptulose and it is speculated that response to D-mannoheptulose may be dependent on secretion of glucagon.
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  • 2
    ISSN: 0148-7280
    Keywords: oocyte maturation ; LH ; ovum culture ; germinal vesicle breakdown ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Immature rats, aged 27 days, were stimulated to develop preovulatory follicles by subcutaneous injection of 15 IU of pregnant mare serum gonadotrophin (PMSG). Two days later their oocytes were collected. They were cultured under conditions that permitted continuous observation. Times of the initial stages of maturation were carefully noted, in the absence and the presence of 10 μg/ml of bovine luteinizing hormone (LH). LH did not accelerate germinal vesicle disappearance. It was concluded that the immature PMSG-treated rat was not an appropriate model for the study of LH action; it was speculated that persistence of PMSG mimicked LH in all the oocytes from such donors.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 6 (1982), S. 1-10 
    ISSN: 0148-7280
    Keywords: rat ; superpregnancy ; preimplantation wastage ; zygote development ; uterotubal zygote transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The development of zygotes in immature, superovulated, and adult female rats was followed by flushing their oviducts and uteri on each of the days L1-L4 (LO is day of sperm finding). Superovulated rats showed a 3.6 times greater rate of preimplantation losses. The loss occurred between L1 and L2 in immatures and was restricted to some of the females; in matures the loss was between L3 and L4. In the immatures some zygotes were already in the uterus on L2. The loss of zygotes in the immature rats is attributed to accelerated transport leading to expulsion as well as lysis of some zygotes within the tract. These latter may be the zygotes identified as morphologicaly abnormal. It is speculated that PMSG may force the ovulation of unfit oocytes.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 1 (1978), S. 27-37 
    ISSN: 0148-7280
    Keywords: oocyte ; fertilization ; incorporation cone ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: At the time of in vivo sperm-egg fusion in the rat, a small region of the oolemma under the head of the fertilizing sperm is observed to be free of microvilli. The microvilli-free region increases in area, and by one hour after sperm-egg contact extends over an area 20-30 μ in circumference and bulges out to form an “incorporation cone” visible by light microscopy. The microvilli-free incorporation cone reaches its maximum size at about two hours after sperm-egg interaction. It soon becomes smaller and has disappeared three to four hours after sperm-oocyte fusion. The cone cytoplasm is characterized by a 0.1 μ zone of thin filaments below the plasma membrane. Cytochalasin-B, 2.5 μg/ml, prevents formation of the cone or destroys the intact cone. It is suggested that micro filaments may be involved in the formation of the incorporation cone.
    Additional Material: 15 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 1 (1978), S. 59-63 
    ISSN: 0148-7280
    Keywords: oocyte maturation ; LH ; ovum culture ; germinal vesicle breakdown ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The purpose of this study was to analyze the effect of luteinizing hormone (LH) on the earliest stage of oocyte maturation - the stage of breakdown of the dictyate nucleus. Oocytes were isolated from the preovulatory follicles of adult, cyclic rats. They were incubated in culture medium with or without 10 μg/ml LH. The cultures were observed continuously for up to 3 hours. Analysis of the rate of disappearance of the germinal vesicle nucleolus revealed that LH accelerated the breakdown process. The median times of disappearance were 91.3 minutes without LH and 62.3 minutes with LH. This is in accord with earlier reports on enhancement of fertilizability of oocytes matured in vitro with LH. Thus, although oocytes mature spontaneously in culture, the maturation remains LH sensitive.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 1 (1978), S. 281-285 
    ISSN: 0148-7280
    Keywords: calcium ; fertilization in vitro ; rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The purpose of this study was to develop a modification of the medium of Toyoda and Chang which would permit high rates of fertilization in vitro in rats of our colony. Elevation of the calcium concentration from 1.71 to 3.42 mM increased the fertilization rate by 87%. Greater additions of calcium gave no further improvement. This effect was not due to reduction in phosphate activity, nor was it due to antagonism of heavy-metal contamination. Although calcium is known to enhance the fertilizing capacity of spermatozoa, our results suggest that it may also affect the oocyte.
    Additional Material: 2 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 115-119 
    ISSN: 0148-7280
    Keywords: cumulus oophorus ; ovulation ; progesterone ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study was designed to determine whether cumulus oophorus cells secrete progesterone. Immature PMS-primed, hCG-treated rats were used. Their cumuli were isolated from pre-ovulatory (no hCG) and peri-ovulatory (after hCG) follicles, and from post-ovulatory oviducal ampullae. Treatment with hCG increased progesterone secretion by almost two-and-one-half-fold. It was speculated that the cumulus oophorus secretion of progesterone modifies the accumulation of fluid in the ampulla, thus providing the medium in which fertilization takes place.
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  • 8
    ISSN: 0148-7280
    Keywords: rat ; superovulation ; superpregnancy ; preimplantation wastage ; zygote survival aminoglutethimide phosphate ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The purpose of this study was to test the hypothesis that the preimplantation losses of zygotes in pregnant superovulated juvenile rats was due to an imbalance of ovarian hormones. Twenty-seven or twenty-eight-day-old rats were injected with 20 iu of PMSG, 25 iu of hCG 50 hr later and mated overnight. From a mean ovulation rate of 52 ± 2 only 16 ± 4 zygotes survived after 4 days. After ligation of the cervical ends of the uteri on the day following fertilization the mean yield of zygotes was 22 ± 6. Ovariectomy on the day of fertilization increased the yield of zygotes to 39 ± 6, but the recovery of the zygotes was seriously complicated by postoperative adhesions and deformations of the adnexa. Inhibition of steroidogenesis with aminogluthehimide phosphate also increased the yield of zygotes. The optimal dose was 45 mg in six divided doses over 3 days, which gave a mean recovery of 57 ± 3 zygotes (of which 75% were blastocysts), that is 100% salvage. A lower dose (30 mg) reduced the recovery to the level of untreated animals, while increasing it to 60 mg resulted in maternal mortality and morbidity, as well as in developmental retardation of zygotes.
    Additional Material: 2 Tab.
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  • 9
    ISSN: 0148-7280
    Keywords: rat ; oocyte maturation ; cumulus mucification ; progesterone ; luteinizing hormone ; fertilization in vitro ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effects of luteinizing hormone (NIH-bovine LH) and progesterone on maturation in vitro of oocyte-cumulus complexes from adult proestrous rats were studied by comparing proportions of oocytes showing germinal vesicle breakdown, mucification of the cumulus oophorus, and fertilizability. Addition of either or both of the hormones to the medium in concentrations between 1.25 and 10 μg/ml during maturation had no discernible effect on germinal vesicle breakdown or on fertilization. Mucification was stimulated by LH and even more by LH plus progesterone. It was concluded that maturation in vivo is the result of concerted action of the two hormones. However, addition of LH + progesterone had no effect on the fertilizability of these oocytes. We attribute this to a relative insensitivity of the system for fertilization in vitro to subtle changes in the oocyte.
    Additional Material: 3 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 11 (1985), S. 99-106 
    ISSN: 0148-7280
    Keywords: rat ; fertilization in vitro ; oocytes ; cleavage (time of) ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The purpose of this study was to analyze the effect of postovulatory ‘aging’ in the oviduct on the rate of zygotic development. Two ovulatory ages were tested: oocytes collected from the oviducal ampullae 1) soon after ovulation (denoted freshly ovulated) or 2) 7-hour postovulation. All the oocytes were from superovulated immature rats. By manipulation of the timing of the ovulatory hormone treatment, it was possible to place both types of oocytes into sperm suspension from the same pool and at the same time. The oocytes and spermatozoa were coincubated overnight. Cleavage was established by interference contrast microscopy. The time of the first cleavage of ova from the 7-hour postovulation group was clearly advanced. Because the cleavage time curves were not parallel, no reliable estimate of the time difference could be made, but it was clearly in the range of 2 hr. This shift could not be related to any difference in the time of sperm penetration. Both groups of oocytes underwent penetration by spermatozoa at the same time. The time interval between maximal sperm penetration (94% of oocytes in both groups) and maximal cleavage (50% in both groups) was 23 hr in the freshly ovulated and 21 hr in the 7-hour postovulatory eggs. Nor was the difference related to polyspermy, which was approximately 14% in both groups. These results support the hypothesis that developmental processes are under way in the oocyte before fertilization, but at a much slower rate than after fertilization.
    Additional Material: 1 Ill.
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