Intramembrane proteolysis: theme and variations

Proteases that reside in cellular membranes apparently wield water to hydrolyze the peptide bonds of substrates despite their water-excluding environment. Although these intramembrane proteases bear little or no sequence resemblance to classical water-soluble proteases, they have ostensibly converged on similar hydrolytic mechanisms. Identification of essential amino acid residues of these proteases suggests that they use residue combinations for catalysis in the same way as their soluble cousins. In contrast to classical proteases, however, the catalytic residues of intramembrane proteases lie within predicted hydrophobic transmembrane domains. Elucidating the biological functions of intramembrane proteases, identifying their substrates, and understanding how they hydrolyze peptide bonds within membranes will shed light on the ways these proteases regulate crucial biological processes and contribute to disease.     

Retrospective and prospective studies of transmissible viral proventriculitis in broiler chickens in Brazil

We investigated the occurrence and pathologic findings of transmissible viral proventriculitis (TVP) associated with the chicken proventricular necrosis virus (CPNV) in commercial broiler chickens in southeastern Brazil. Seventy-three broilers, 25–36 d old, with a history of reduced growth, were referred to our veterinary pathology services from 2013 to 2017. Broilers were clinically examined, weighed, and euthanized for postmortem examination. Broilers of different ages with proventricular histologic lesions were positive for CPNV by RT-PCR; however, the intensity of histologic lesions was higher among 33-d-old animals, and viral RNA detection was more frequent among those that were 28 d old. In the proventriculi of 35 of 73 (48%) broilers, lesions were characterized by glandular epithelial necrosis, lymphoplasmacytic and histiocytic infiltrates, and metaplasia of glandular epithelium to ductal epithelium. In 24 of 73 (36%) broilers with histologic TVP-compatible lesions, CPNV was detected by RT-PCR for the viral protein 1 (VP1) gene. Broilers with histologic lesions were lighter than expected compared to the Cobb 500 standard weight. TVP has not been reported previously in broiler chickens in Brazil, to our knowledge.     

Radiography and computed tomography of the heart and lower respiratory tract in toco toucans (Ramphastos toco)

This study aimed to evaluate normal features of the heart and lower respiratory tract in toco toucans by means of radiography and helical computed tomography (CT) scanner. Fifteen healthy adult toco toucans (Ramphastos toco), 10 females and 5 males, average body mass of 650 g were studied. CT examination as well as right lateral and ventrodorsal radiographic examinations of the coelomic cavity were performed under chemical restraint. Heart, lungs, air sacs, trachea and syrinx were analysed. The mean values of heart length, heart width and thoracic cavity in radiographs were, respectively, 23.76 mm, 25.94 mm and 48.87 mm. In both X-rays and CT scans, the lung parenchyma had honeycomb-like pattern. The topographic areas of the anterior and posterior air sacs were visualized as dark and air-filled spaces in X-rays. On CT evaluation, the air sacs occupied a larger area in the coelomic cavity compared to X-ray. In the lateral radiographic view, the cervical part of the trachea was positioned more ventrally in the transition from cervical to thoracic regions showing a V-shaped appearance. In all CT planes was visible division of the trachea into the right and left main bronchi at the level of 3rd thoracic vertebra. The syrinx was difficult to visualize in X-rays, but on CT it was easily identified in axial slice. In conclusion, the normal features of toco toucan's heart and lower respiratory tract that were determined on X-rays and CT scans are useful to compare with sick toco toucans, as well as other bird species.     

Reproductive performance in South Australian dairy herds

SUMMARY Herd breeding records (161) were examined from a random 10% sample of dairy farms (96) in South Australia with more than 40 cows and suitable breeding records for 1988 and/or 1989. Of these farms, 53 (55.2%) had a year-round calving pattern, 42 (43.8%) claimed to be seasonal and one was changing from a year-round to a seasonal pattern. Only 14.6% of farmers observed oestrous behaviour outside milking times and 18.8% used tailpaint. Overall, the average proportion of unobserved heats was estimated to be 32%. Artificial insemination (AI) was carried out on 85.4% of farms (16.7% used AI alone and 68.7% also used bulls) of which 32.9% used commercial technicians and 67.1% were do-it-yourself operators. Overall, the average 30-day submission rate was 59.9% and the average 49-day non-return to service rate was 58.9%. Investigation into the probable causes of suboptimal reproductive performance gave a tentative diagnosis of inefficient oestrous detection, deferral of service, inadequate nutrition, poor AI technique, insufficient bulls, and venereal/other diseases in 69.1, 32.1, 27.2, 28.4, 13.6 and 7.4% of records, respectively.     

The Oxidative Stress,Antioxidant Profile and Acid–base Status in Preterm and Term Canine Neonates

During the initiation of neonatal pulmonary respiration, there is an exponential increase in reactive oxygen species that must be scavenged by antioxidant defences. However, neonate and preterm newborns are known to possess immature antioxidant mechanisms to neutralize these toxic effects. The purposes of this study were to compare the development of antioxidant system between preterm and term canine neonates and to evaluate the magnitude of acid–base balance during the initial 4 h of life. A prospective study was conducted involving 18 neonatal puppies assigned to Term Group (63 days of gestation; n = 5), Preterm‐57 Group (57 days of gestation; n = 8) and Preterm‐55 Group (55 days of gestation; n = 5). Neonates were physically examined through Apgar score and venous haemogasometry within 5 min, 2 and 4 h after birth. No difference on amniotic fluid and serum superoxide dismutase (SOD), glutathione peroxidase (GPx) and the marker of oxidative stress (thiobarbituric acid reactive substances; TBARS) was verified. Irrespective of prematurity, all neonates presented low vitality, hypothermia, acidosis, hypoxaemia and hypercapnia at birth. However, term puppies clinically evolved more rapidly than preterm newborns. During the course of the study, premature neonates presented more severe complications, such as prolonged hypoxaemia and even death. In conclusion, premature puppies have no signs of immature enzymatic mechanisms for controlling oxidative stress, although SOD and GPx may participate in achieving acid–base balance. Aside from initial unremarkable symptoms, premature puppies should be carefully followed up, as they are at high risk of succumbing to odds of prematurity.     

ELASTOGRAPHIC EVALUATION OF NATURALLY OCCURING TENDON AND LIGAMENT INJURIES OF THE EQUINE DISTAL LIMB

Compression elastography is an ultrasonographic technique that estimates tissue strain and may have utility in diagnosing and monitoring soft tissue injuries in the equine athlete. Recently, elastography has been proven to be a feasible and repeatable imaging modality for evaluating normal tendons and ligaments of the equine distal forelimb. The purposes of this prospective study were to investigate the ability of elastography to detect spontaneously occurring lesions of equine tendons and ligaments diagnosed with magnetic resonance imaging (MRI) and gray‐scale ultrasound (US) and to characterize the differences in the elastographic appearance of acute vs. chronic injuries. Fifty seven horses with a total of 65 lesions were evaluated. Images were assessed quantitatively and qualitatively. Acute lesions were found to be significantly softer (P < 0.0001) than chronic lesions (P < 0.0001) and the stiffness of lesions increased with progression of healing (P = 0.0138). A negative correlation between lesion hypoechogenicity and softness was appreciated with more hypoechoic lesions appearing softer (P = 0.0087) and more hyperechoic regions harder (P = 0.0002). A similar finding occurred with increased signal intensity on short tau inversion recovery (STIR) and proton density (PD) MRI sequences correlating with increased softness on elastography (P = 0.0164). Using US and MRI as references, commonly encountered soft tissue injuries of the equine distal limb could be detected with elastography. However, elastography was limited for detecting small, proximal injuries of the hindlimb proximal suspensory ligament. Elastographic evaluation of equine tendons and ligaments may allow better characterization of lesion chronicity and severity, and sequential examinations may optimize lesion management, rehabilitation, and return to training.     

Attenuation of allergic contact dermatitis through the endocannabinoid system

Allergic contact dermatitis affects about 5% of men and 11% of women in industrialized countries and is one of the leading causes for occupational diseases. In an animal model for cutaneous contact hypersensitivity, we show that mice lacking both known cannabinoid receptors display exacerbated allergic inflammation. In contrast, fatty acid amide hydrolase-deficient mice, which have increased levels of the endocannabinoid anandamide, displayed reduced allergic responses in the skin. Cannabinoid receptor antagonists exacerbated allergic inflammation, whereas receptor agonists attenuated inflammation. These results demonstrate a protective role of the endocannabinoid system in contact allergy in the skin and suggest a target for therapeutic intervention.