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991.
Although AA requirements for the mean in a population of growing pigs are well established, there are no direct estimates of their variability within the population. The indicator AA oxidation method allows repeated measurements in a short period of time so that the AA requirement can be determined for individual pigs. The objective was to determine the Lys requirement in individual pigs to derive a first estimate of the population mean requirement and its variability. Nine individually housed barrows (15 to 18 kg) were surgically implanted with venous catheters for isotope infusion. Pigs were offered, in random order, isonitrogenous and isoenergetic diets with one of seven Lys concentrations (4.8 to 15.5 g of Lys/kg diet, as-fed basis). The pigs were fed twice daily, except for study days when they received one-half of the daily allowance in eight equal hourly meals. After a validated minimum adaptation period, indicator (Phe) oxidation was determined for each dietary Lys level during a 4-h primed, constant infusion of L-[1-(14C)]Phe at a rate of 464 kBq/h. The Lys requirement was calculated using a two-phase linear regression crossover analysis within individual pigs. For each pig, Phe oxidation decreased linearly (P < 0.02) as the dietary Lys concentration increased until the requirement was reached; thereafter, Phe oxidation was not different. The true ileal digestible Lys requirement ranged from 7.5 to 10.6 g/kg of diet (as-fed basis) for the nine animals. The mean requirement for all pigs was 9.1 g/d (CV, 11.6%) or 93.9% (CV, 9.8%) of the predicted (NRC, 1998) requirement based on each pig's mean BW and energy intake. The measured and predicted requirements did not differ. The indicator AA oxidation method gave values for Lys requirement similar to conventional methods. The short (< 3 wk) experimental period allows, for the first time, the estimate of population variability, which provides for more accurate calculation of the effect of altering Lys intake on herd performance and production economics. This method is suitable to use with all dietary indispensable AA.  相似文献   
992.
Chondrocytes dedifferentiate to a fibroblast‐like phenotype on plastic surfaces. Dedifferentiation is reversible if these cells are then cultured embedded in gels as alginate, agarose or collagen. Chondrocytes cultured in suspension on a non‐adherent surface are also known to form aggregates of differentiated cells. The knowledge of chondrocyte behavior in culture is relevant for tissue engineering purposes. In this report we describe a simple method to culture differentiated or redifferentiated rabbit auricular chondrocytes on plastic surfaces with a stable phenotype. When chondrocyte aggregates formed in suspension are next seeded on plastic surfaces, most of them attach to the plastic as round or polygonal cells, and this morphological differentiation, confirmed by the presence of type II collagen, is stable for long culture periods. We also report that the addition of aggregates to monolayer cultures of dedifferentiated chondrocytes results in their redifferentiation, as is shown by their morphological changes and the synthesis of type II collagen. Therefore, this simple method can be useful for the study of chondrocyte behavior on plastic surfaces and for redifferentiating previously proliferated chondrocytes in tissue engineering techniques. Furthermore, these results demonstrate that, in addition to culture conditions such as cell isolation method or cell‐density, chondrocyte behavior on plastic depends on the presence or absence of aggregates resulting from the dissociation process.  相似文献   
993.
Genetic and phylogenetic analyses of the region containing the glycoprotein (G) gene, which is related to pathogenicity and antigenicity, and the G-L intergenic region were carried out in 14 Brazilian rabies virus isolates. The isolates were classified as dog-related rabies virus (DRRV) or vampire bat-related rabies virus (VRRV), by nucleoprotein (N) analysis. The nucleotide and amino acid (AA) homologies of the area containing the G protein gene and G-L intergenic region were generally lower than those of the ectodomain. In both regions, nucleotide and deduced AA homologies were lower among VRRVs than among DRRVs. There were AA differences between DRRV and VRRV at 3 antigenic sites and epitopes (IIa, WB+ and III), suggesting that DRRV and VRRV can be distinguished by differences of antigenicity. In a comparison of phylogenetic trees between the ectodomain and the area containing the G protein gene and G-L intergenic region, the branching patterns of the chiropteran and carnivoran rabies virus groups differed, whereas there were clear similarities in patterns within the DRRV and VRRV groups. Additionally, the VRRV isolates were more closely related to chiropteran strains isolated from Latin America than to Brazilian DRRV. These results indicate that Brazilian rabies virus isolates can be classified as DRRV or VRRV by analysis of the G gene and the G-L intergenic region, as well as by N gene analysis.  相似文献   
994.
The object of this study was to investigate the role of epidermal growth factor (EGF) and IGF-I in the regulation of preantral follicular growth, antrum formation, and granulosal cell proliferation/ apoptosis. Porcine preantral follicles were manually dissected and cultured for up to 8 d in Waymouth's (Exp. 1) or alpha-minimum Eagle's essential medium (Exp. 2 and 3) supplemented with 10 microg/mL of transferrin, 100 microg/mL of L-ascorbic acid, and 2 mU/mL of ovine FSH, in the presence (Exp. 1 and 3) or absence (Exp. 2) of 7.5% fetal calf serum. According to the experimental protocol, IGF-I (0, 1, 10, or 100 ng/mL; Exp. 1), or IGF-I (50 ng/mL), EGF (10 ng/mL) and EGF+IGF-I (Exp. 2 and 3) were added to the culture media. In Exp. 1, follicles exhibited a concentration-dependent response (P < 0.05) to IGF-I, with the highest rates of granulosal cell proliferation, follicular integrity, and recovery rate of cumulus cell-oocyte complexes and lowest incidence of apoptosis occurring at the highest IGF-I dose. In Exp. 2 serum-free medium, granulosal cell proliferation was low (1 to 5%), irrespective of whether EGF and/or IGF-I were present and cellular apoptosis was increased (P < 0.05) on d 4 and 8 in the EGF+IGF-I group compared with the addition of either factor alone. In Exp. 3, granulosal cell proliferation was high in all follicles cultured in serum-containing medium for the first 3 d, but fell sharply (P < 0.05) on d 4, except in media containing IGF-I. Collectively, EGF and IGF-I increased granulosal cell proliferation, decreased apoptosis, and promoted follicular antrum formation. These results may provide useful information for developing a preantral follicular culture system in which the oocytes are capable of fertilization and embryonic development.  相似文献   
995.
A Geographic Information System (VetEpiGIS) was used to analyze the ADV (Aujeszky's disease virus) sero-status in large-scale pig units regarding certain geographical features in a county of southern Hungary. The ADV sero-statuses were collected from all swine units in Csongrád county in 1998-2000. The units' coordinates were combined with a vector graphical digital map of the county, with a resolution of 1:100,000. Logistic regression tested the associations between sero-status of large-scale units and presence of topographical features, other units and villages in the neighborhood. "Neighborhood" was defined by circular zones with radius 1-10km around the unit (in 1km increments; one logistic regression for each radius). The following topographical features showed significant positive association with the ADV seropositivity: lake (3km OR: 5.7; 5km OR: 7.5; 6km OR: 6.1; 10km OR: 5.4) and highway (5km OR: 4.2; 6km OR: 5.3). Other features had negative association with ADV seropositivity: forest (3km OR: 0.13; 4km OR: 0.15; 5km OR: 0.15; 6km OR: 0.10; 7km OR: 0.10; 8km OR: 0.23) and uninfected large-scale unit (4km OR: 0.07; 5km OR: 0.27; 6km OR: 0.32; 7km OR: 0.31).  相似文献   
996.
OBJECTIVE: To determine the pharmacokinetics of doxorubicin in sulphur-crested cockatoos, so that its use in clinical studies in birds can be considered. DESIGN: A pharmacokinetic study of doxorubicin, following a single intravenous (i.v.) infusion over 20 min, was performed in four healthy sulphur-crested cockatoos (Cacatua galerita). PROCEDURE: Birds were anaesthetised and both jugular veins were cannulated, one for doxorubicin infusion and the other for blood collection. Doxorubicin hydrochloride (2 mg/kg) in normal saline was infused i.v. over 20 min at a constant rate. Serial blood samples were collected for 96 h after initiation of the infusion. Plasma doxorubicin concentrations were assayed using an HPLC method involving ethyl acetate extraction, reverse-phase chromatography and fluorescence detection. The limit of quantification was 20 ng/mL. Established non-parametric methods were used for the analysis of plasma doxorubicin data. RESULTS: During the infusion the mean +/- SD for the Cmax of doxorubicin was 4037 +/- 2577 ng/mL. Plasma concentrations declined biexponentially immediately after the infusion was ceased. There was considerable intersubject variability in all pharmacokinetic variables. The terminal (beta-phase) half-life was 41.4 +/- 18.5 min, the systemic clearance (CI) was 45.7 +/- 18.0 mL/min/kg, the mean residence time (MRT) was 4.8 +/- 1.4 min, and the volume of distribution at steady state (V(SS)) was 238 +/- 131 mL/kg. The extrapolated area under the curve (AUC(0-infinity)) was 950 +/- 677 ng/mL x h. The reduced metabolite, doxorubicinol, was detected in the plasma of all four parrots but could be quantified in only one bird with the profile suggesting formation rate-limited pharmacokinetics of doxorubicinol. CONCLUSIONS AND CLINICAL RELEVANCE: Doxorubicin infusion in sulphur-crested cockatoos produced mild, transient inappetence. The volume of distribution per kilogram and terminal half-life were considerably smaller, but the clearance per kilogram was similar to or larger than reported in the dog, rat and humans. Traces of doxorubicinol, a metabolite of doxorubicin, were detected in the plasma.  相似文献   
997.
998.
The onset of action and behavioural effects following intravenous (i.v.) and intramuscular (i.m.) administration of 0.05, 0.5, 1.0, 2.0 and 5.0 mg/kg of midazolam were studied for 2 h in 20 awake, healthy cats. All cats, except one that received 0.05 mg/kg i.m., showed effects of the drug, whereas no effects were observed in cats administered only the vehicle in which midazolam was dissolved. The onset of action was rapid following both i.v. and i.m. administration, some cats became ataxic, while others assumed positions of sternal or lateral recumbency. Even after administration of the highest dose (5.0 mg/kg), anaesthesia was not induced, with swallowing reflexes and conscious perception of a clamp placed on the tail still present in all cats. An abnormal arousal state was observed in many cats after administration of midazolam. During the first hour, restlessness was more commonly observed, while from 1 to 2 h, sedation was more prominent in cats that received the highest dose. Ataxia occurred in all but one cat, was short-lived in cats that received the lower doses, but still present at 2 h in all cats that received 2.0 and 5.0 mg/kg. Midazolam caused some of the cats to behave differently when approached and restrained compared with behavioural patterns identified prior to administration of the drug. The cats were more likely to behave abnormally following i.v. administration rather than i.m. administration and, for the most part, abnormal behaviour was equally distributed between the two extremes; cats being easier to approach and restrain and cats being more difficult to approach and restrain. Food consumption increased significantly, during the 2 h period, following all i.m. doses and all but the highest (5.0 mg/kg) i.v. dose, with most of the food being consumed in the first hour after administration.  相似文献   
999.
1000.
Two-year-old crossbred beef heifers were used to test the effects of porcine relaxin (pRelaxin) alone, or in combination with dexamethasone, on the induction of parturition, the incidence of dystocia, and retained placentas. Effects of treatment on pelvic area, postpartum interval, milk production, colostrum quality, calf birth weight, calf vigor, and calf performance were also evaluated. On Day 275 of gestation, heifers from two fetal-sire groups were randomly assigned to one of four groups in a 2 × 2 factorial design and received: no treatment (controls, N = 19), 20 mg of dexamethasone intramuscularly (im) (n = 22), 5 mg of pRelaxin (3,000 U/mg) im (n = 19), or 20 mg of dexamethasone plus 5 mg of pRelaxin (n = 17). Length of gestation (in days) was less (P < 0.05) in heifers treated with dexamethasone (279.8 ± 1.0) than in controls (286.6 ± 0.9), but was not influenced (P > 0.05) by treatment with pRelaxin. The incidence of retained placentas in heifers treated only with dexamethasone (27.3%) was not reduced by concomitant treatment with pRelaxin (35.3%). Retained placentas were not observed in any control heifers and in only one heifer (5.2%) treated solely with pRelaxin. Ease of calving (1 = unassisted, 5 = abnormal presentation) was not influenced by treatment (P > 0.05), even though birth weights (in kilograms) of calves from heifers treated with dexamethasone (36.4 ± 0.8) were less (P < .01) than those of calves from nondexamethasone-treated heifers (39.2 ± 0.8). Dexamethasone tended to reduce (P < 0.07) calf vigor (1 = healthy and strong, 5 = dead on arrival; 1.48 ± 0.11 vs. 1.18 ± 0.11), but was not (P > 0.05) influenced by pRelaxin. The duration of the postpartum anestrous interval (73.1 ± 1.8 d across groups) and pelvic areas following treatment and parturition were not influenced (P > 0.05) by dexamethasone or pRelaxin. Although determinants of colostrum quality (P < 0.01) and quantity (P < 0.08) of milk produced were influenced by dexamethasone, adjusted 205-d weights of calves did not differ (P > 0.05) among groups. In conclusion, treatment with pRelaxin alone failed to induce parturition or, when combined with dexamethasone, to reduce the incidence of retained placentas.  相似文献   
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