排序方式： 共有50条查询结果，搜索用时 15 毫秒
1.
Effects of diet restriction on life span and age-related changes in dogs 总被引：11，自引：0，他引：11
Kealy RD Lawler DF Ballam JM Mantz SL Biery DN Greeley EH Lust G Segre M Smith GK Stowe HD 《Journal of the American Veterinary Medical Association》2002,220(9):1315-1320
OBJECTIVE: To evaluate the effects of 25% diet restriction on life span of dogs and on markers of aging. DESIGN: Paired feeding study. ANIMALS: 48 Labrador Retrievers. PROCEDURES: Dogs were paired, and 1 dog in each pair was fed 25% less food than its pair-mate from 8 weeks of age until death. Serum biochemical analyses were performed, body condition was scored, and body composition was measured annually until 12 years of age. Age at onset of chronic disease and median (age when 50% of the dogs were deceased) and maximum (age when 90% of the dogs were deceased) life spans were evaluated. RESULTS: Compared with control dogs, food-restricted dogs weighed less and had lower body fat content and lower serum triglycerides, triiodothyronine, insulin, and glucose concentrations. Median life span was significantly longer for dogs in which food was restricted. The onset of clinical signs of chronic disease generally was delayed for food-restricted dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that 25% restriction in food intake increased median life span and delayed the onset of signs of chronic disease in these dogs. 相似文献
2.
3.
Grant JA Arvidson R Bell JF Cabrol NA Carr MH Christensen P Crumpler L Des Marais DJ Ehlmann BL Farmer J Golombek M Grant FD Greeley R Herkenhoff K Li R McSween HY Ming DW Moersch J Rice JW Ruff S Richter L Squyres S Sullivan R Weitz C 《Science (New York, N.Y.)》2004,305(5685):807-810
The Mars Exploration Rover Spirit has traversed a fairly flat, rock-strewn terrain whose surface is shaped primarily by impact events, although some of the landscape has been altered by eolian processes. Impacts ejected basaltic rocks that probably were part of locally formed lava flows from at least 10 meters depth. Some rocks have been textured and/or partially buried by windblown sediments less than 2 millimeters in diameter that concentrate within shallow, partially filled, circular impact depressions referred to as hollows. The terrain traversed during the 90-sol (martian solar day) nominal mission shows no evidence for an ancient lake in Gusev crater. 相似文献
4.
Cutts JA Blasius KR Briggs GA Carr MH Greeley R Masursky H 《Science (New York, N.Y.)》1976,194(4271):1329-1337
During October 1976, the Viking 2 orbiter acquired approximately 700 high-resolution images of the north polar region of Mars. These images confirm the existence at the north pole of extensive layered deposits largely covered over with deposits of perennial ice. An unconformity within the layered deposits suggests a complex history of climate change during their time of deposition. A pole-girdling accumulation of dunes composed of very dark materials is revealed for the first time by the Viking cameras. The entire region is devoid of fresh impact craters. Rapid rates of erosion or deposition are implied. A scenario for polar geological evolution, involving two types of climate change, is proposed. 相似文献
5.
Wind tunnel experiments have revealed a characteristic flow field pattern over raised-rim craters which causes distinctive zones of aeolian erosion and deposition. Comparisons of the results with Mariner 9 images of Mars show that some crater-associated dark zones result from wind erosion and that some crater-associated light streaks are depositional. 相似文献
6.
Greeley EH Spitznagel E Lawler DF Kealy RD Segre M 《Veterinary immunology and immunopathology》2006,111(3-4):287-299
Caloric restriction (CR) has been shown to retard immunosenescence and to extend median and maximum life span in rodent species. Longitudinal effects of CR on the canine immune system are presented in this report. A group of 48 Labrador Retrievers, divided at weaning into weight- and sex-matched pairs, were maintained on a diet restriction protocol from age 8 weeks until death. Each restricted dog received 75% of the total food consumed by its control-fed pair mate. Immune parameters were monitored from 4 to 13 years. CR retarded age-related declines in both lymphoproliferative responses and absolute numbers of lymphocytes and the T, CD4, and CD8-cell subsets. In females, CR attenuated the age-related increase in T-cell percentages and marginally retarded the age-related increase in memory cell percentages. Age-related changes in B-cell percentages and numbers were augmented by CR. No direct effect of CR on phagocytic activity of PMN, antibody production or NK cell activity, was observed. Lower lymphoproliferative responses, lower numbers of lymphocytes, T, CD4 and CD8 cells, lower CD8 percentages and higher B-cell percentages were all found to be significantly associated with a decreased likelihood of survival in these dogs. 相似文献
7.
Reported herein are hematocrit and total and differential WBCs obtained from 132 clinically healthy male and female white-footed mice (Peromyscus leucopus) of four different age groups: 4, 5-8, 9-20, and >32 wk old. Minimal differences were identified between the age groups. The number and percentage of neutrophils in the 4-wk-old mice were significantly higher than those in the other groups; the relative percentage of lymphocytes in the 4-wk-old mice was significantly lower than in the 9-20-wk-old mice. The only significant gender effects identified were higher numbers of WBCs and lymphocytes in females of the 4-wk-old group and higher hematocrits in males of the 5-8- and >32-wk-old groups. 相似文献
8.
CH Annandale PC Irons VP Bagla UI Osuagwuh EH Venter 《Reproduction in domestic animals》2010,45(2):250-255
The objectives of this work were to determine the site of persistence of lumpy skin disease virus (LSDV) in bulls shedding the virus in semen for a period longer than 28 days, to determine if the virus is present in all fractions of semen and to study lesions that developed in the genital tract. Six serologically negative postpubertal bulls were experimentally infected with a virulent field isolate of LSDV. The polymerase chain reaction (PCR) was performed on sheath washes, vesicular fluid, supernatant and cell‐rich fractions of semen from day 10 to day 26 postinfection (p.i.). Bulls that were positive by PCR on the whole semen sample collected on day 28 p.i. were slaughtered and tissue samples from their genital tracts submitted for histopathological evaluation, immunoperoxidase staining, virus isolation and PCR. Two of the bulls developed severe lumpy skin disease (LSD) and were found to be shedding viral DNA in their semen on day 28 p.i. Viral DNA was identified in all semen fractions from all bulls, but mostly from the cell‐rich fraction and from the severely affected bulls. The PCR assay was positive on postmortem samples of testes and epididymides from the two severely affected bulls. Virus could be recovered from the testes of these two bulls and from the epididymis of one of them. Immunoperoxidase staining was positive for LSDV staining in sections of testes and epididymides exhibiting necrosis. This study suggests that the testis and epididymis are sites of persistence of LSDV in bulls shedding virus in semen for prolonged periods and revealed that viral DNA is present in all fractions of the ejaculate. 相似文献
9.
S Gür G Türk E Demirci A Yüce M Sönmez Ş Özer EH Aksu 《Reproduction in domestic animals》2011,46(2):289-295
The aim of this study was to determine the changes in diameter of corpus luteum (CL), maternal progesterone (P) concentration, lipid peroxidation and non‐enzymatic antioxidant levels along with enzymatic antioxidant activities in pregnant ewes bearing single and twin foetuses. The ewes were selected from healthy animals that were brought to the abattoir for slaughtering. The ewes were divided into three groups: Group 1 (non‐pregnant, non‐oestrous, n = 30), Group 2 (pregnant bearing a single foetus, n = 30) and Group 3 (pregnant bearing twin foetuses, n = 12) after they were slaughtered. Pregnant ewes were in the first half of the pregnancy. The diameter of CL and P concentration of pregnant ewes bearing a single foetus or twin foetuses were found higher than that found in non‐pregnant ewes. Similarly, the P concentration of pregnant ewes bearing twin foetuses was higher than that found in pregnant ewes bearing a single foetus. Malondialdehyde (MDA) level in pregnant ewes bearing twin foetuses was higher than that found in both non‐pregnant and pregnant ewes bearing a single foetus. The serum glutathione (GSH) level and glutathione‐peroxidase (GSH‐Px) activity of pregnant ewes bearing twin foetuses were found lower than that found in non‐pregnant ewes. Additionally, the GSH‐Px activity of pregnant ewes bearing twin foetuses was found lower than that found in pregnant ewes bearing a single foetus. No significant difference was found between pregnant ewes bearing female and male foetus with respect to diameter of CL, P concentration and oxidative stress parameters. There were significant positive correlations between foetal number (0, 1, 2) and diameter of CL, P concentration, MDA level, and between P concentration and diameter of CL, MDA level. However, significant negative correlations were found between foetal number (0, 1, 2) and GSH level, GSH‐Px activity, and between P concentration and GSH‐Px activity. In conclusion, the diameter of CL enlarges, P production increases and oxidant/antioxidant balance impairs because of the gestation stress in ewes during pregnancy. 相似文献
10.
Greeley JP 《Science (New York, N.Y.)》2012,336(6083):810-811