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排序方式: 共有65条查询结果,搜索用时 15 毫秒
1.
Köster LS Schoeman JP Meltzer DG 《Journal of the South African Veterinary Association》2007,78(3):133-136
Serum cortisol response was assessed in 8 captive cheetahs, of varying ages, after the intravenous administration of 500 microg of tetracosactide (Synacthen Depot, Novartis, Kempton Park) while maintained under general anaesthesia. In addition, 8 cheetahs were anaesthetised and given an equal volume of saline in order to establish baseline cortisol concentrations at similar stages of anaesthesia. A significant difference in the median cortisol concentration measured over time was found following ACTH administration in the ACTH group (P < 0.001). There was no difference between the median cortisol concentrations in the ACTH group at time-points 120, 150 and 180 min after ACTH stimulation (P = 0.867). Thus it appears appropriate to collect serum 120 to 180 min after tetracosactide administration to assess maximal stimulation of the adrenal in the cheetah. No statistically significant rise was seen in the anaesthetised control group following the injection of saline (P = 0.238). 相似文献
2.
N. Snapir J. Rulf A. Meltzer G. Gvaryahu I. Rozenboim B. Robinzon 《British poultry science》1998,39(4):572-574
1. Mule ducks were produced by naturally mating Muscovy drakes and Khaki Campbell ducks. 2. Semen was collected from 6-month-old mule drakes via an artificial vagina. The fluid was clear without any spermatozoa or spermatids. 3. Testes from 27-week-old mule drakes were smaller in size than those of Khaki Campbell drakes but heavier than Muscovy males of the same age. Histological sections of these testes revealed that spermatogenesis was not complete. 4. Testosterone concentration in the mule drakes was higher than in Muscovy males but similar to Khaki Campbell drakes. 5. Mule drakes have strong sexual drives as a result of high concentrations of testosterone, but, because spermatogenesis is incomplete, their semen had no sperm. 相似文献
3.
Yonow T Brewster CC Allen JC Meltzer MI 《The Onderstepoort journal of veterinary research》1998,65(4):263-273
We present a simple model of the dynamics of heartwater that we use to explore and better understand various aspects of this disease. We adapted the Ross-Macdonald model for malaria epidemiology so that we could consider both host and vector populations, and evaluate the interactions between the two. We then use two more biologically detailed models to examine heartwater epidemiology. The first includes a carrier state and host mortality, and the second includes density dependence. The results from all three models indicate that a stable equilibrium with high disease levels is probably the standard situation for heartwater (R0 between 5.7 and 22.4). More than 80% of cattle become infected with heartwater if only 12% of infected tick bites produce an infection in cattle, if tick burdens are as low as only five ticks per host per day, or if tick lifespans are as short as 7 d. A host recovery rate of 30 d results in over 50% of the cattle becoming infected with heartwater. Our analyses indicate that it is quite difficult to prevent the establishment and maintenance of high levels of heartwater in a herd, thereby supporting previous suggestions that any attempts at controlling this disease through stringent tick control regimens are not warranted. 相似文献
4.
Brantsaeter AL Haugen M Rasmussen SE Alexander J Samuelsen SO Meltzer HM 《Public health nutrition》2007,10(8):838-847
OBJECTIVE: To validate a new food-frequency questionnaire (FFQ) for measuring the intake of fruit, vegetables and tea reported by women participating in the Norwegian Mother and Child Cohort Study (MoBa). DESIGN: Intake of fruits, vegetables and tea estimated by the FFQ was compared with urinary flavonoid excretion, plasma carotenoid concentration and intake measured by a 4-day weighed food diary (FD). The triangular method was applied to calculate FFQ validity coefficients using two independent biomarkers. SETTING AND SUBJECTS: One hundred and nineteen women participating in MoBa. RESULTS: The FFQ estimate of fruit intake was significantly correlated with urine phloretin (r = 0.33), citrus fruit/juice with urine hesperetin (r = 0.44), cooked vegetables with plasma alpha-carotene (r = 0.37), and tea with urine kaempferol (r = 0.41) (P < 0.01 for all). On average, 60% of the participants fell into the same or adjacent quintiles when classified by FFQ and biomarkers. Significant correlations between the FFQ and FD were found for fruit (r = 0.39), vegetables (r = 0.34), juices (r = 0.50) and tea (r = 0.53). The FFQ validity coefficient was 0.65 for citrus fruit/juice and 0.59 for cooked vegetables as calculated by the triangular method. CONCLUSIONS: The validation study shows that the MoBa FFQ can be used to estimate fruit, juice, vegetable and tea intake in pregnant Norwegian women, and to rank individuals within the distribution. 相似文献
5.
Meltzer SJ 《Science (New York, N.Y.)》1916,43(1115):675-680
6.
Airan RD Meltzer LA Roy M Gong Y Chen H Deisseroth K 《Science (New York, N.Y.)》2007,317(5839):819-823
The hippocampus is one of several brain areas thought to play a central role in affective behaviors, but the underlying local network dynamics are not understood. We used quantitative voltage-sensitive dye imaging to probe hippocampal dynamics with millisecond resolution in brain slices after bidirectional modulation of affective state in rat models of depression. We found that a simple measure of real-time activity-stimulus-evoked percolation of activity through the dentate gyrus relative to the hippocampal output subfield-accounted for induced changes in animal behavior independent of the underlying mechanism of action of the treatments. Our results define a circuit-level neurophysiological endophenotype for affective behavior and suggest an approach to understanding circuit-level substrates underlying psychiatric disease symptoms. 相似文献
7.
8.
Suppression of macrophage activation and T-lymphocyte function in hypoprolactinemic mice 总被引:22,自引:0,他引:22
The effects of prolactin on lactation and reproductive organs are well known. However, the other possible target organs and physiological consequences of altered levels of circulating prolactin remain poorly understood. In this study, mice were treated with bromocryptine, a dopamine receptor agonist that inhibits pituitary prolactin secretion. Bromocryptine treatment prevented T-cell-dependent induction of macrophage tumoricidal activity after the intraperitoneal injection of Listeria monocytogenes or Mycobacterium bovis. Coincident treatment with ovine prolactin reversed this effect. Of the multiple events leading to macrophage activation in vivo, the production by T-lymphocytes of gamma-interferon was the most impaired in bromocryptine-treated mice. Lymphocyte proliferation after stimulation with mitogens in vitro was also depressed in spleens of bromocryptine-treated mice, and coadministration of prolactin also reversed this effect. Bromocryptine treatment also reduced the number of deaths resulting from inoculation of mice with Listeria; exogenous prolactin significantly reversed this effect. The critical influence of pituitary prolactin release on maintenance of lymphocyte function and on lymphokine-dependent macrophage activation suggests that, in mice, lymphocytes are an important target tissue for circulating prolactin. 相似文献
9.
10.
Genetic basis for species vulnerability in the cheetah 总被引:31,自引:0,他引:31
S J O'Brien M E Roelke L Marker A Newman C A Winkler D Meltzer L Colly J F Evermann M Bush D E Wildt 《Science (New York, N.Y.)》1985,227(4693):1428-1434
A population genetic survey of over 200 structural loci previously revealed that the South African cheetah (Acinonyx jubatus jubatus) has an extreme paucity of genetic variability, probably as a consequence of a severe population bottleneck in its recent past. The genetic monomorphism of the species is here extended to the major histocompatibility complex, since 14 reciprocal skin grafts between unrelated cheetahs were accepted. The apparent consequences of such genetic uniformity to the species include (i) great difficulty in captive breeding, (ii) a high degree of juvenile mortality in captivity and in the wild, and (iii) a high frequency of spermatozoal abnormalities in ejaculates. The species vulnerability of the cheetah was demonstrated by an epizootic of coronavirus-associated feline infectious peritonitis in an Oregon breeding colony in 1983. Exposure and spread of the coronavirus, which has a very low morbidity in domestic cats (approximately 1 percent), has decimated a heretofore productive and healthy captive population. The extreme genetic monomorphism, especially at the major histocompatibility complex, and the apparent hypersensitivity of the cheetah to a viral pathogen may be related, and provide a biological basis for understanding the adaptive significance of abundant genetic variation in outbred mammalian species. 相似文献