Pituitary receptors for GnRH and estradiol, and pituitary content of gonadotropins in beef cows. I. Changes during the estrous cycle     

T M Nett  D Cermak  T Braden  J Manns  G Niswender 《Domestic animal endocrinology》1987,4(2):123-132

To further characterize the endocrinological changes in the hypothalamo-hypophyseal axis thoughout the bovine estrous cycle, cycling beef heifers (n = 24) were randomly assigned to six groups. These heifers were slaughtered 6, 12, 18, 19, 20 or 21 days following their previous estrus (day 0). Anterior pituitaries and hypothalami were collected. Hypothalami were divided into the preoptic area and medial basal hypothalamus, and content of gonadotropin-releasing hormone (GnRH) was quantified by radioimmunoassay. Contents of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in the anterior pituitary gland were quantified by radioimmunoassay. Membrane receptors for GnRH were quantified by a standard curve technique and receptors for estradiol in anterior pituitary cytosol were quantified by saturation analysis. There was no significant change in content of GnRH in the hypothalamus or content of FSH in the anterior pituitary on any of the days examined; however, content of GnRH in the preoptic area was lower (P less than .1) on day 19 postestrus. Cytosolic receptors for estradiol increased (P less than .05) on day 18 post-estrus and returned to baseline by day 19. Content of LH and the number of receptors for GnRH in the anterior pituitary gland decreased (P less than .01) on day 19 postestrus, and the number of receptors for GnRH remained low through day 21 postestrus. The reduction in anterior pituitary content of LH was transient indicating that synthesis of LH restores pituitary content to preovulatory levels before the number of receptors for GnRH returns to normal.  相似文献   

Mechanisms of luteolysis in domestic livestock   总被引：1，自引：1，他引：1  

J J Knickerbocker  M C Wiltbank  G D Niswender 《Domestic animal endocrinology》1988,5(2):91-107

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Temperature-induced momentum-dependent spectral weight transfer in Bi2Sr2CaCu2O8+delta     

Z Shen  PJ White  DL Feng  C Kim  GD Gu  H Ikeda  R Yoshizaki  N Koshizuka 《Science (New York, N.Y.)》1998,280(5361):259-262

Angle-resolved photoemission data from the cuprate superconductor Bi2Sr2CaCu2O8+delta above and below the superconducting transition temperature Tc reveal momentum-dependent changes that extend up to an energy of about 0.3 electron volt, or 40kTc (where k is the Boltzmann constant). The data suggest an anomalous transfer of spectral weight from one momentum to another, involving a sizable momentum transfer Q approximately (0.45pi, 0). The observed Q is intriguingly near the charge-order periodicity required if fluctuating charge stripes are present.  相似文献   

Pb isotopic variability in melt inclusions from oceanic island basalts, polynesia     

AE Saal  SR Hart  N Shimizu  EH Hauri  GD Layne 《Science (New York, N.Y.)》1998,282(5393):1481-1484

Previous studies have suggested that melting processes are responsible for the trace element variability observed in olivine-hosted basaltic melt inclusions. Melt inclusions from three individual lava samples (two from Mangaia, Cook Islands, and one from Tahaa, Society Islands) have heterogeneous Pb isotopic compositions, even though the erupted lavas are isotopically homogeneous. The range of Pb isotopic compositions from individual melt inclusions spans 50 percent of the worldwide range observed for ocean island basalts. The melt inclusion data can be explained by two-component mixing for each island. Our data imply that magmas with different isotopic compositions existed in the volcanic plumbing system before or during melt aggregation.  相似文献   

Piroxicam and doxycycline treatment for an oral squamous cell carcinoma in an inshore bottlenose dolphin (Tursiops aduncus)          下载免费PDF全文

DT March  DJ Blyde  GD Bossart  AP Begg  DP Taylor  V McClure 《Australian veterinary journal》2016,94(6):203-207

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Rigid removable cover for dorsal wound protection and tube fixation in pigs          下载免费PDF全文

GD Stynes  GK Kiroff  WA Morrison  GA Edwards  RS Page  MA Kirkland 《Australian veterinary journal》2016,94(4):111-116

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Epidemiology of Bovine Venereal Campylobacteriosis: Geographic Distribution and Recent Advances in Molecular Diagnostic Techniques     

GD Mshelia  JD Amin  Z Woldehiwet  RD Murray  GO Egwu 《Reproduction in domestic animals》2010,45(5):e221-e230

Bovine venereal campylobacteriosis (BVC) is a major cause of economic loss to the cattle industries in different parts of the world. Camplylobacter fetus subsp. venerealis (Cfv), the main causative agent of BVC, is highly adapted to the genital tract of cattle and is transmitted by carrier bulls. However, infertility and abortions can also be caused by the intestinal pathogens C. fetus subsp. fetus (Cff), and C. jenuni, which are not venereally transmitted. Bovine venereal campylobacteriosis, caused by Cfv associated with lowered fertility, embryo mortality and abortion, repeated returns to service, reduced pregnancy rates and extended calving intervals, has the highest prevalence in developing countries where natural breeding in cattle is widely practised. The epidemiology, pathogenesis and diagnosis of the disease have been the subject of previous reviews. The main focus of this review is to highlight the epidemiology of this disease with particular reference to geographical distribution and recent advances in molecular diagnostic techniques. It is hoped that further research interest of scientists will be stimulated with a view to finding lasting solutions to the reproductive problems associated with the disease for better livestock productivity, particularly in developing endemic countries.  相似文献   

The effects of ventilation on intercranial and cerebral perfusion pressures in isoflurane-anaesthetized horses     

RJ Brosnan  EP Steffey  RA LeCouteur  A Imai  GD Kortz 《Veterinary anaesthesia and analgesia》2002,29(2):91-92

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Induction of ovulation with deslorelin: Options to facilitate implant removal     

Patrick M. McCue DVM  PhD  Diplomate ACT  Kory D. Niswender MS  DVM  Valerie J. Farquhar MS 《Journal of Equine Veterinary Science》2002,22(2)

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Release of FSH and LH in beef heifers by synthetic gonadotrophin releasing hormone   总被引：1，自引：0，他引：1  

C C Kaltenbach  T G Dunn  T E Kiser  L R Corah  A M Akbar  G D Niswender 《Journal of animal science》1974,38(2):357-362

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