Enzyme histochemical features of equine gluteus muscle fibers

Gluteal muscle specimens were taken from 4 horses. From 1 of the 4 gluteal muscles, serial sections were prepared. Individual muscle fibers were identified and studied, using photomicrographs of sections stained by different enzyme histochemical methods. In specimens in which cytoplasmic soluble enzymes were studied, use was made of the semi-permeable membrane technique to hamper enzyme diffusion into reaction fluids. Enzymes involved in glycogenolysis, glycolysis, the tricarboxylic acid cycle, synthesis of reduced nicotinamide adenine dinucleotide phosphate, the pentose phosphate cycle, the alpha-glycerolphosphate shuttle, the respiratory chain, catabolism, and muscular contraction were studied. Some key enzymes of different metabolic pathways were also included. Each of 3 fiber types identified had distinct features. Type I fibers were characterized by a relatively strong aerobic capacity, compared with type IIA fibers, which were more glycolytic and had strong aerobic and moderate-to-strong anaerobic capacity. Type IIB fibers were characterized by a relatively low aerobic and a relatively high anaerobic capacity, and were glycolytic. Activities of phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and alpha-naphtylesterase (nonspecific esterase) were so markedly different in the 3 fiber types that fiber typing was possible, aided by the demonstration of the activities of these enzymes. In type IIB fibers, the pentose phosphate cycle was more important than in the other fiber types. Except for the unexplained high alpha-naphtylesterase activity in type IIB fibers, catabolic enzymes were not active in healthy equine muscle fibers.     

The effects of canthaxanthin on porcine oocyte maturation and embryo development in vitro after parthenogenetic activation and somatic cell nuclear transfer

The objective of this study was to examine the effects of canthaxanthin (Cx) treatment during in vitro maturation (IVM) of porcine oocytes on embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT), on intracellular glutathione (GSH) and reactive oxygen species (ROS) levels in mature oocytes, and on gene expression in both PA‐ and SCNT‐derived blastocysts. To determine the optimal effective concentration of Cx, porcine oocytes were cultured in IVM medium supplemented with various concentrations (0, 20, 40 and 80 μM) of Cx for 22 hr. Compared to other groups, supplementation with 40 μM Cx significantly improved blastocyst formation rates after PA (p < .05), but no significant differences were observed among groups in total blastocyst cell numbers. Subsequently, oocytes were cultured in IVM medium supplemented with or without 40 μM Cx. Oocytes treated with 40 μM Cx showed significantly increased cleavage and blastocyst formation rates after SCNT compared to the control group (p < .05). Moreover, significantly increased intracellular GSH and reduced ROS levels were observed in the Cx‐treated group (p < .05). In addition, both PA‐ and SCNT‐derived blastocysts from the 40 μM Cx‐treated group showed significantly increased mRNA expression of Bcl2 and Oct4 and decreased Caspase3 expression level (p < .05), when compared with the control group. PA‐derived blastocysts from the 40 μM Cx‐treated group also exhibited significantly decreased expression of Bax (p < .05). Our results demonstrated that treatment with 40 μM Cx during IVM improves the developmental competence of PA and SCNT embryos. Improvement of embryo development by Cx is most likely due to increased intracellular GSH synthesis, which reduces ROS levels in oocytes, and it may also positively regulate apoptosis‐ and development‐related genes.     

Effects of EGLN1 siRNA on growth of rat pulmonary artery smooth muscle cells under hypoxic condition

AIM: To observe whether EGLN1 gene is involved in the growth of pulmonary arterial smooth muscle cells (PASMCs) during hypoxia when EGLN1 gene expression was interference by siRNA. METHODS: The rat primary pulmonary arterial smooth muscle cells were cultured, and the specific lipidosome of EGLN1 siRNA was constructed and transfected into the PASMCs. The transfected PASMCs were cultured under hypoxia or normoxia conditions, respectively. The viability of the PASMCs was detected by CCK-8 assay. The protein expression of EGLN1 and vascular endothelial growth factor (VEGF) was determined by Western blot. RESULTS: The viability of the PASMCs was increased and the protein expression of VEGF was up-regulated in the PASMCs under hypoxic condition in a time-dependent manner. In hypoxia or normoxia condition, the viability and VEGF protein expression of the PASMCs were suppressed by EGLN1 siRNA. CONCLUSION: EGLN1 gene may involve in the growth of rat PASMCs by regulating VEGF protein level under hypoxic condition.     

Prevalence and risk factors for medical events following exercise at Australian Greyhound race meetings

Aim

A prospective, observational study to determine the prevalence of post‐exercise conditions at Australian Greyhound race meetings and to assess association with race performance and other environmental, race‐ and dog‐related factors was undertaken.

Methods

A total of 4020 starters were observed (2813 Greyhounds, 1009 trainers, 536 races, 52 race meets, 48 race dates and 11 race tracks) following a race. The presence of diaphragmatic flutter (DF), ataxia, seizure, collapse or sudden death was recorded. Risk factors were screened by univariable logistic regression prior to multivariable backward stepwise model building.

Results

In this study, 962 starters (n = 768 dogs) had DF (23.9%), 16 starters were ataxic (0.4%) and there were no observed cases of collapse, seizure or sudden death. Race track location, increasing race distance, race grade based on increasing 1st place prize value, lower (earlier) race number at the meeting, age, a previous observation of DF at the last start, females, colour (white) and better finishing position were all associated with an increased risk of a Greyhound being observed with DF. However, when logistic regression assessing the random effect of dog was performed, the presence of previous DF was not significant. In this cohort, DF was common following strenuous exercise in Greyhounds and on its own does not appear to result in reduced performance or distress to the animal.

Conclusion

The incidence of ataxia was low and collapse, seizure and sudden death were not observed. However, even though uncommon, ataxia has welfare concerns for racing Greyhounds that warrants further investigation.     

Intramuscular dosing strategy for ampicillin sodium in horses, based on its distribution into tissue chambers before and after induction of inflammation

The Pharmacokinetics (PK) and distribution into tissue chamber fluid (TCF) of intramuscularly (i.m.) administered ampicillin sodium were examined in horses in order to design adequate dosing strategies. Concentration-time curves of ampicillin in plasma and TCF were determined in six horses following administration of 15 mg/kg ampicillin sodium, before and after the induction of local inflammation with 0.5% carrageenan. The calculated parameters were used to simulate various dosage-dosing interval combinations. Ampicillin was absorbed very rapidly following i.m. administration. Plasma concentrations were maximual between 18 and 21 min after administration. None of the plasma PK parameters were affected significantly by local (TC) inflammation. Penetration of ampicillin into and elimination from the TCF were affected significantly by inflammation and the half-life of elimination from the tissue fluid t1/2(d) was significantly shorter in inflammation. In the simulated dosage-dosing interval scenarios, only a dosage of 15 mg ampicillin/kg four times daily would successfully treat all ampicillin-susceptible bacterial isolates in well vascularized tissues. However a dosage as low as 10 mg/kg twice daily, would, in theory, treat all ampicillin-susceptible isolates in the inflamed poorly vascularized tissues. Decreasing the dosage results in loss of efficacy that cannot be completely compensated for by increasing the frequency of dosing.     

乔科型藏羊遗传资源保护及制种供种体系建设思路

作者通过调查乔科型藏羊遗传资源现状,发现乔科型藏羊纯种数量当前仍有不断下降的风险,为了避免乔科型藏羊种群数量不断减少,作者分析了乔科型藏羊种质资源的优良特性,总结了开展乔科型藏羊遗传资源保护的意义,提出了乔科型藏羊遗传资源保护及制种供种体系建设的思路,并提出了建议。