Hip dysplasia and dog breeding

Summary

Hip dysplasia is considered to be one of the most serious problems in dog breeding. In the past 20 years the studies of, and the attempts to control, this condition have been directed mainly to the overall picture of the abnormality of the hips. The various efforts have resulted in a decrease in the incidence of HD in several breeds of dogs. For other breeds the results have not been very convincing, however. In some instances they are even said to be conflicting with other aims of breeding. Based on these data some separate studies have recently been performded in respect of the details of the disorders in the hip joints and of the heritability of these elements.

The present study concerns itself with the roots of the disorders as they are observed in the various breeds. A great variety of data indicates that selection within the canine species for specific morphological traits must be considered as one of the most important roots of the occurrence of HD. The collected data strongly indicate that improvements in the HD status in the various breeds can be reached by selection against specific disorders of the hip joints in these breeds.     

Progress in studying the mechanism of fever using knockout mice

Increasing evidence suggests that a complex net-work of fever induction pathways in mammalian exists. In this article, the overview of recent studies on the mechanism of fever induced by different pyrogens using IL-1, IL-1R, ICE, IL-1ra, IL-1RacP, IL-6, IL-10, TNFR, cPLA₂, COX, EP, AT₂, iNOS and D_2/3 knockout mice is presented. Hyperthermia respond to localized infection/inflammation (e.g., sc injection of turpentine) is mediated by IL-1β and IL-6 in turn.While fever induced by systemic infection/inflammation (e.g., treatment with LPS intraperitoneally) varies with the different doses of pyrogens administered. Fever caused by a low dose of LPS administered ip is IL-6 dependent, but the IL-6 independent pathway is crucial for the fever evoked by a high dose of LPS. Febrile responses during both local and systemic infection/inflammation develop totally through central PGE₂ dependent mechanism, but some stress induced hyperthermia otherwise.     

不同方法对受体母牛诱导同期发情效果的比较

为了给胚胎移植受体牛选择高效的同期发情方法,选出99头本年引进南阳牛作为胚胎移植受体牛进行试验,采用一次前列腺素注射法(随机注射)、海绵栓 PMSG PG法、口服孕酮法3种方法处理对比.结果显示:一次前列腺素法受体牛同期发情率达到25%,48小时同期率达到14.3%,受胎率达到35.7%;海绵栓 PMSG PG法受体牛同期发情率达到75%,48小时同期率达到62.5%,受胎率达到44.4%;口服孕酮法受体牛同期发情率达到50%,48小时同期率达到33.3%,受胎率达到44.4%.海绵栓 PMSG PG法有较高的同期发情率和受胎率,并且处理成本低(85.8元),是3种方法中最优的一种.     

Localization of cyclooxygenase isozymes in cardiovascular tissues of dogs treated with naproxen

Prostaglandins have diverse roles in the cardiovascular system mediating both physiologic and inflammatory responses. Two cyclooxygenase isoforms, cyclooxygenase-1 and cyclooxygenase-2, catalyze prostaglandin production. In many tissues and cell types studied, cyclooxygenase-1 is constitutively active whereas cyclooxygenase-2 expression is primarily responsible for prostaglandin production during inflammation. However, little information exists concerning which isoform is responsible for prostaglandin-mediated effects in the heart. We examined cyclooxygenase-1 and cyclooxygenase-2 expression in heart and vascular tissue of dogs using isoform-specific antibodies. In addition, tissues from dogs treated with naproxen (5–10 mg/kg/day), an inhibitor of prostaglandin production were also examined. Cyclooxygenase-1 expression was evident in endothelial cells of the microvasculature of the heart, aorta and renal artery. Cyclooxygenase-1 expression was also found in fibrocytes of the tricuspid valve and in the chordae tendinae. Animals treated with naproxen exhibited a similar pattern and intensity of cyclooxygenase-1 staining. No cyclooxygenase-2 expression was evident in cardiac tissue. However, minimal cyclooxygenase-2 immunoreactivity was present in the vascular endothelial cells of small myocardial blood vessels located in several regions of the heart as well as in endothelial cells of the aorta. These data may expand our understanding of the effects of non-steroidal anti-inflammatory drugs on cardiac function.     

Ovarian steroids modulate tumor necrosis factor-α and nitric oxide-regulated prostaglandin secretion by cultured bovine oviductal epithelial cells

Ovarian steroids assure an optimum environment for the final maturation of oocytes, gamete transport, fertilization, and early embryonic development. The aim of experiment 1 was to examine the influence of ovarian steroids on tumor necrosis factor-α (TNF-α)- or nitric oxide (NO)-regulated prostaglandin (PG), and nitrite/nitrate (NO₂/NO₃) secretion by cultured bovine oviductal epithelial cells (BOECs). BOECs were pretreated with 17β-estradiol (E₂; 10⁻⁹ M) and/or progesterone (P₄; 10⁻⁷ M) for 24 h. For the next 24 h, BOECs were treated with TNF-α (10 ng/mL) or spermine nitric oxide complex (NONOate; 10⁻⁵ M). Prostaglandin F_2α and PGE₂ secretion was measured in medium by ELISA. The pretreatment of cells with P₄ (progesterone), E₂ (17 β-estradiol), or E₂/P₄ augmented TNF-α-induced PGF_2α and PGE₂ secretion (P < 0.01). The pretreatment of cells with E₂ or E₂/P₄ increased NONOate-induced PGF_2α and PGE₂ secretion (P < 0.01). TNF-α induced NO₂/NO₃ production by BOECs. The pretreatment of cells with E₂ augmented only TNF-α-induced NO₂/NO₃ production (P < 0.05). The aim of experiment 2 was to examine the influence of TNF-α, NO, and ovarian steroids on the protein content of enzymes specifically involved in PG and NO production, PG synthases, and NO synthases (NOSs). BOECs were treated with TNF-α (10 ng/mL) or NONOate (10⁻⁵ M). TNF-α increased the protein content of PGG/H synthase, PGF synthase, and PGE synthase (P < 0.05) and endothelial and inducible NOSs (P < 0.05). Nitric oxide increased the protein content of PGF synthase, PGE synthase, endothelial NOS, and inducible NOS (P < 0.05). These results show possible linkage between TNF-α and NO, modulated by ovarian steroids, in the regulation of PG synthesis by BOECs that may be important for triggering the process of oviductal contractions.     

Expression of Glucocorticoid Receptor α and Its Regulation in the Bovine Endometrium: Possible Role in Cyclic Prostaglandin F2α Production

Cortisol (Cr), the most important glucocorticoid (GC), is well known to suppress uterine prostaglandin F2α (PGF) production. However, the details of the regulatory mechanisms controlling the cyclic changes in endometrial PGF production remain unclear. Here we investigated the expression of the GC receptor (GC-Rα), the actions of cortisol throughout the estrous cycle and the regulatory mechanism of GC-Rα in the bovine endometrium. The levels of GC-Rα protein were greater at the mid-luteal stage (Days 8–12) than at the other stages. Cr more strongly suppressed PGF production at the mid-luteal stage than at the follicular stage. GC-Rα expression was increased by progesterone (P4) but decreased by estradiol-17β (E2) in cultured endometrial stromal cells. The overall results suggest that ovarian steroid hormones control the cyclic changes in endometrial PGF production by regulating GC-Rα expression in bovine endometrial stromal cells.     

雌激素对荷斯坦奶牛输卵管上皮细胞中前列腺素E2受体EP2和EP4 mRNA表达的影响

本实验旨在探讨奶牛输卵管上皮细胞中是否存在前列腺素E2受体EP2和EP4,且该受体mRNA表达是否受雌激素(E2)的调控。将前列腺素类化合物PGE2和受体选择性激动剂(butaprost)按10-9mol/L-10-5mol/L的浓度分别作用于体外培养的奶牛输卵管上皮细胞,应用Elisa方法检测细胞中第二信使cAMP量的变化。然后,将E2作用于体外培养的奶牛输卵管上皮细胞,应用real time RT-PCR技术检测EP2和EP4受体mRNA表达量的变化。Elisa实验结果显示,前列腺素类化合物PGE2和受体选择性激动剂(butaprost)可引起奶牛输卵管上皮中cAMP量的变化,且cAMP量具有对PGE2和butaprost浓度依存性的变化规律,表明奶牛输卵管上皮细胞中存在前列腺素受体EP2和EP4。Real time RT-PCR实验结果表明,奶牛输卵管上皮细胞中存在前列腺素受体EP2和EP4,且E2对EP2和EP4受体mRNA的表达具有调控作用,低浓度(10-12mol/L)可提高该受体mRNA的表达量。