5-bromo-2'-deoxyuridine blocks myogenesis by extinguishing expression of MyoD1   总被引：16，自引：0，他引：16  

S J Tapscott  A B Lassar  R L Davis  H Weintraub 《Science (New York, N.Y.)》1989,245(4917):532-536

The pyrimidine analog 5-bromodeoxyuridine (BUdR) competes with thymidine for incorporation into DNA. Substitution of BUdR for thymidine does not significantly affect cell viability but does block cell differentiation in many different lineages. BUdR substitution in a mouse myoblast line blocked myogenic differentiation and extinguished the expression of the myogenic determination gene MyoD1. Forced expression of MyoD1 from a transfected expression vector in a BUdR-substituted myoblast overcame the block to differentiation imposed by BUdR. Activation of BUdR-substituted muscle structural genes and apparently normal differentiation were observed in transfected myoblasts. This shows that BUdR blocks myogenesis at the level of a myogenic regulatory gene, possibly MyoD1, not by directly inhibiting the activation of muscle structural genes. It is consistent with the idea that BUdR selectively blocks a class of regulatory genes, each member of which is important for the development of a different cell lineage.  相似文献   

Trenbolone acetate/estradiol combinations in feedlot steers: dose-response and implant carrier effects.     

S J Bartle  R L Preston  R E Brown  R J Grant 《Journal of animal science》1992,70(5):1326-1332

Two experiments were conducted at three locations to determine the correct dosage and carrier for trenbolone acetate (TBA) and estradiol (E2) implants in feedlot steers. In the dose-response experiment, 1,296 steers were allotted to six implant treatments (48 pens per location): control, 140 mg of TBA (140/0), 30 mg of E2 (0/30), 20 mg of TBA + 4 mg of E2(20/4), 80 mg of TBA + 16 mg of E2(80/16), and 140 mg of TBA + 28 mg of E2 (140/28). In the carrier experiment, 575 steers were allotted to five implant treatments (25 pens per location): control, 140 mg of TBA + 28 mg of E2 in lactose (140/28-LA), 140 mg of TBA + 28 mg of E2 in cholesterol (140/28-CH), 140 mg of TBA + 20 mg of E2 in LA (140/20-LA), and 200 mg of progesterone + 20 mg of E2 benzoate (SS, reimplanted). In both experiments steers were fed a finishing diet for 140 to 168 d. In the dose-response experiment, response to TBA alone (140/0) did not differ from control (P greater than .2). Estradiol alone (0/30) improved ADG by 7% (P less than .01) and tended to improve feed efficiency over control (3%, P = .17). The highest dosage (140/28) improved ADG by 18% (P less than .001) and feed efficiency by 10% (P less than .001) over control and 10% (P less than .001) and 7% (P less than .01) over E2 alone, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Riding arenas and different riding track surfaces in relation to the airway contamination in horses. Laboratory studies on riding surfaces]     

H J Rapp  F J Bockisch  R Weiss  M Becker  M Stechele  K Heisse 《Tier?rztliche Praxis》1992,20(5):503-508

29 samples of commonly used surfaces were tested for their water characteristics (litre weight, water capacity, water binding, water evaporation) and their contribution to airborne fungal spores (dust formation, dust setting). The results are discussed in comparison to the literature with regard to the environment. The results are: 1. Any surface--no matter of what material--eventually causes air pollution with fungal spores and dust. 2. Correct watering prevents air pollution by any surface. 3. Artificial products have no advantage over natural materials in the parameters tested. 4. The question of proper disposal of old surface material has to be clarified before purchase. The results show that a mixture of sand and wood shavings should be recommended as a surface for indoor arenas, especially in regard to environmental protection and proper disposal.  相似文献   

COMPARISON OF FOUR EXTENDERS FOR LONG-TERM STORAGE OF FRESH BOAR SEMEN     

J.P. Laforest  D. Allard 《Reproduction in domestic animals》1995,31(1):275-276

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Acquired syringomyelia in a dog.     

L Cauzinille  J N Kornegay 《Journal of the American Veterinary Medical Association》1992,201(8):1225-1228

Acquired syringomyelia was diagnosed in an 11-year-old Fox Terrier with progressive paresis in the left pelvic limb. Myelography and magnetic resonance imaging confirmed an intramedullary lesion involving the left dorsolateral portion of the spinal cord at the level of L-2 and L-3 vertebrae. Clinical signs improved after surgical syringotomy. Microscopic evaluation of a biopsy specimen from the cyst wall did not establish a definitive histologic diagnosis. The cyst was decreased in size on magnetic resonance imaging 7 months later.  相似文献   

Humoral recognition of lipopolysaccharide core antigens of gram-negative bacteria in neonatal swine     

J W Tyler  J S Cullor  M C Thurmond  D W Hird  K M Parker 《American journal of veterinary research》1989,50(1):126-130

Serologic recognition of common lipopolysaccharide core antigens has been related to enhanced resistance to gram-negative bacterial disease in several species. Class-specific titers (IgG, IgM) were determined by direct ELISA, using intact Escherichia coli (J5) as a plate antigen. Serum samples were obtained from 224 neonatal swine between the ages of 36 and 60 hours. The mean (+/- SEM) log10 IgG titer against gram-negative core antigens was 1:1,713 +/- 0.4718 and the mean log10 IgM titer was 1:202 +/- 0.5644. The IgG titer was directly related with litter size, birth weight, and serum total IgG concentration; IgM titer was directly related with dam parity and serum total IgG concentration.  相似文献   

瘤胃阳离子和可溶性蛋白与牛易感受苜蓿膨胀病的关系   总被引：1，自引：0，他引：1  

Hall  JW 《牧草与饲料》1989,(1):53-56

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Pathotypes of Synchytrium endobioticum in Germany     

E. LANGERFELD  H. STACHEWICZ  J. RINTELEN† 《EPPO Bulletin》1994,24(4):799-804

Results are given of a survey on the occurrence of pathotypes (races) of Synchytrium endobioticum (potato wart) in both parts of re-unified Germany. An assortment of six differential cultivars appears to be sufficient to distinguish between the seven presently important German wart pathotypes. A total of ten pathotypes was recorded. Two West and two East German pathotypes seem to be identical, based on the results obtained with presently available cultivars. In contrast to pathotype 1 (common race) which prior to 1945 was distributed over the whole German territory, the 'new' pathotypes seem to prefer the central and south German mountain areas.  相似文献   

Heterosis and recombination effects in Hampshire and Landrace swine: II. Performance and carcass traits.     

T J Baas  L L Christian  M F Rothschild 《Journal of animal science》1992,70(1):99-105

Twelve different mating types among the Hampshire and Landrace breeds were used to determine direct, maternal, heterosis, and recombination effects for performance and carcass traits. Mating types used were two purebred, two F1, two F2, two F3, and four backcross. Carcass data were collected on 238 barrows and 262 gilts over four replications. Traits measured were length (LENG), 10th rib off midline backfat (BF10), longissimus muscle area (LMA), and dressing percentage (DRS%). Average backfat (AVBF) was calculated as the mean of three midline fat depths measured opposite the first rib, last rib, and last lumbar vertebra. The model used to evaluate the carcass traits included main effects of mating type, farrowing season, and sex and included slaughter weight as a covariate. The performance traits of ADG, feed efficiency (FE), daily feed consumption (DFC), lean gain per day (LNGN), and lean efficiency (LNEF) were measured on a pen basis. Comparisons of reciprocal F1 crosses showed that carcasses from pigs sired by Hampshire boars were leaner and had more LMA than those sired by Landrace boars. Heterosis percentages were significant for AVBF (7.2%; P less than .01), BF10 (8.8%; P less than .01), DRS% (1.5%; P less than .01), ADG (11.5%; P less than .01), DFC (10.2%; P less than .01), LNGN (10.6%; P less than .01), and LNEF (6.0%; P less than .05). Epistatic recombination losses in the offspring were significant for LENG (3.6 cm; P less than .05) and approached significance for BF10 (6.1 mm; P less than .10).  相似文献   

Pharmacokinetic evaluation of ceftiofur in serum, tissue chamber fluid and bronchial secretions from healthy beef-bred calves.          下载免费PDF全文

S L Halstead  R D Walker  J C Baker  R E Holland  G E Stein    J G Hauptman 《Canadian journal of veterinary research》1992,56(4):269-274

Ceftiofur is a new broad spectrum cephalosporin marketed for the treatment of acute bovine respiratory disease. In this investigation ceftiofur was administered by intramuscular injection, at 24 h intervals, to healthy beef-bred calves for four days at dosages of 2.2 and 4.4 mg/kg of body weight, with 4 wk intervals between dosing regimens. Serum, tissue chamber fluid (TCF), and bronchial secretion (BS) concentrations of ceftiofur were measured by microbiological assay after the first and fourth dose of each dosing regimen. Peak serum concentrations (Cmax) of 8.8 micrograms/mL and 17.3 micrograms/mL were obtained approximately 2 h (Tmax), the time of mean peak concentration) after single injections of 2.2 mg/kg and 4.4 mg/kg, respectively. The Cmax was increased approximately twofold following multiple doses of 2.2 mg/kg (Cmax = 13.1 micrograms/mL) and 4.4 mg/kg (Cmax = 24.1 micrograms/mL). Ceftiofur accumulated slowly into TCF and peak concentrations were found to be approximately 14% of those observed in serum after the first dose and approximately 24% after multiple dosing. Concentrations of ceftiofur in BS were obtained rapidly with peak concentrations reaching 45% of the serum Cmax after the first dose. After multiple dosing the Cmax for BS was approximately 25% of the serum Cmax. This study found that both the 2.2 mg/kg and 4.4 mg/kg dosing regimens resulted in continuous serum, TCF and BS concentrations of ceftiofur that exceeded the minimal concentration required to inhibit the bacteria most frequently isolated from calves with acute bovine respiratory disease.  相似文献