Ultrasound during mid‐gestation: Agreement with physical foetal and placental measurements and use in predicting gestational age in sheep

To determine the effects of poor maternal nutrition and litter size on foetal growth during mid‐gestation, pregnant ewes (n = 82) were fed 100%, 60% or 140% of NRC TDN beginning at day 30.2 ± 0.2 of gestation. Transabdominal ultrasound was performed weekly between day 46.0 ± 0.4 and 86.0 ± 0.7 to monitor foetal heart width (HW), umbilical diameter (UMB), rib width (RW) and placentome outer (OD) and inner diameter (ID). Data were analysed with repeated‐measures using the mixed procedure for effects of maternal diet, litter size and gestation, and equations predictive of gestational age were generated using the regression procedure. To determine the agreement of ultrasound measurement and actual size, ewes (n = 20–21) were euthanized at day 45 or 90 to obtain corresponding postmortem measurements for Bland–Altman analysis. The HW, UMB and placentome OD and ID increased with gestation (p < .0001) but were unaffected by maternal diet or litter size (p ≥ .12). Ultrasound underestimated postmortem measurements of HW (14.8%), UMB (7.3%), placentome OD (4.5%) and ID (37.3%) at day 90 of gestation. Ultrasound underestimated RW at day 45 (7.7%) but overestimated RW (23.8%) at day 90, indicating inconsistent bias when reporting RW by ultrasound. Combining the HW, UMB, RW and placentome OD generated the strongest equation predictive of gestational age (R² = .91). These findings indicate that during mid‐gestation, maternal diet or litter size did not affect HW, UMB or placentome diameters and these factors can be used to estimate gestational age.     

Sulfur-associated polioencephalomalacia in cattle grazing plants in the Family Brassicaceae

Polioencephalomalacia was diagnosed histologically in cattle from two herds on the Darling Downs, Queensland, during July–August 2007. In the first incident, 8 of 20 18-month-old Aberdeen Angus steers died while grazing pastures comprising 60% Sisymbrium irio (London rocket) and 40% Capsella bursapastoris (shepherd's purse). In the second incident, 2 of 150 mixed-breed adult cattle died, and another was successfully treated with thiamine, while grazing a pasture comprising almost 100% Raphanus raphanistrum (wild radish). Affected cattle were either found dead or comatose or were seen apparently blind and head-pressing in some cases. For both incidents, plant and water assays were used to calculate the total dietary sulfur content in dry matter as 0.62% and 1.01% respectively, both exceeding the recommended 0.5% for cattle eating more than 40% forage. Blood and tissue assays for lead were negative in both cases. No access to thiaminase, concentrated sodium ion or extrinsic hydrogen sulfide sources were identified in either incident. Below-median late summer and autumn rainfall followed by above-median unseasonal winter rainfall promoted weed growth at the expense of wholesome pasture species before these incidents.     

Generation of recombinant antibody fragments that target canine dendritic cells by phage display technology

One of the main goals in cancer immunotherapy is the efficient activation of the host immune system against tumour cells. Dendritic cells (DCs) can induce specific anti-tumour immune responses in both experimental animal models and humans. However, most preclinical studies using small animal models show only limited correlation with studies carried out in clinical settings, whereas laboratory dogs naturally develop tumours that are biologically and histopathologically similar to their human counterparts. Here, we describe the generation and characterization of recombinant antibodies against canine DCs, isolated using the Tomlinson phage display system. We successfully isolated highly specific single-chain variable fragment (scFv) antibodies in a sequential three-step panning strategy involving depletion on canine peripheral blood mononuclear cells followed by positive selection on native canine DCs. This provides the basis for an antibody-based method for the immunological detection and manipulation of DCs and for monitoring antigen-specific immune responses.     

动物疫苗及其合理使用（一）

疫苗接种是预防动物传染病发生的重要举措。依据免疫学理论,疫苗作为抗原,通过激发动物机体免疫系统,产生特异的体液免疫和细胞免疫,从而获得针对某种疾病的特异性免疫。疫苗一般分为细菌疫苗、病毒疫苗和类毒素疫苗等。用于防病治病的各种疫苗、菌苗又是特殊的生物药品,与普通化学药品具有完全不同的成分、功能和特性,疫苗中含有多种蛋白质（除细菌或病毒外,有的还含有保护剂、鸡胚尿囊液或细胞培养液）,它们均适合许多病原体的生长,有些制品还是活的微生物,一旦污染后果不堪设想。疫苗在保存、运输和使用时有其特别要求。如果方法不当,不但会使活性物质失活,起不到免疫防病作用;而且还可能适得其反,引发动物新的疾病,造成重大损失。     

The Functional Role of Oxytocin in the Induction of Oocyte Meiotic Resumption in Cattle

The aim of the present study was to examine the role of oxytocin (OT) in the progesterone (P4) and prostaglandins (PGs) pathway to induce oocyte meiotic resumption. Cumulus–oocyte complexes were co‐cultured with follicular hemisections for 15 h to determine the effects of different doses of OT or atosiban (ATO; oxytocin receptor antagonist) on oocyte meiotic resumption. In another experiment, we examined the effect of the interaction between P4, OT and PGs on the regulatory cascade of the oocyte meiotic resumption. Oxytocin at 1 μm was effective in inducing meiotic resumption in oocytes co‐cultured with follicular cells (84.0%), not differing from the positive control group (74.4%). Atosiban inhibited in a dose‐dependent manner the positive effect of OT on the meiotic resumption (27.6% metaphase I with 10 μm of ATO, which did not differ from the 25.5% of the negative control group). Furthermore, a third experiment showed that P4 was able to induce oocyte meiotic resumption, which was inhibited by ATO. However, the OT positive effect was not blocked by mifepristone (P4 antagonist), but was inhibited by indomethacin (a non‐selective PTGS2 inhibitor). Collectively, these data suggest a sequential role of P4, OT and PGs in the induction of oocyte meiotic resumption.     

Qualitative and quantitative ultrasound attributes of maternal‐foetal structures in pregnant ewes

The aim of this study was to examine foetal organs and placental tissue to establish a correlation between the changes in the composition of these structures associated with their maturation and the ultrasonographic characteristics of the images. Twenty‐four pregnant ewes were included in the study. Ultrasonography assessments were performed in B‐mode, from the ninth gestational week until parturition. The lungs, liver and kidneys of foetuses and placentomes were located in transverse and longitudinal sections to evaluate the echogenicity (hypoechoic, isoechoic, hyperechoic or mixed) and echotexture (homogeneous and heterogeneous) of the tissues of interest. For quantitative evaluation of the ultrasonographic characteristics, it was performed a computerized image analysis using a commercial software (Image ProPlus^®). Mean numerical pixel values (NPVs), pixel heterogeneity (standard deviation of NPVs) and minimum and maximum pixel values were measured by selecting five circular regions of interest in each assessed tissue. All evaluated tissues presented significant variations in the NPVs, except for the liver. Pulmonary NPVmean, NPVmin and NPVmax decreased gradually through gestational weeks. The renal parameters gradually decreased with the advancement of the gestational weeks until the 17th week and later stabilized. The placentome NPVmean, NPVmin and NPVmax decreased gradually over the course of weeks. The hepatic tissue did not show echogenicity and echotexture variations and presented medium echogenicity and homogeneous echotexture throughout the experimental period. It was concluded that pixels numerical evaluation of maternal‐foetal tissues was applicable and allowed the identification of quantitative ultrasonographic characteristics showing changes in echogenicity related to gestational age.