Histologic characterization of spontaneous catecholamine-induced cardiomyopathy in laboratory New Zealand White rabbits.

Catecholamine-induced cardiomyopathy (CCM) is an entity associated with increased levels of catecholamines causing subendocardial and papillary muscle cardiomyocyte degeneration and necrosis. In 2020, 49 autopsies from early rabbit deaths in a colony used for medical device biocompatibility studies were submitted for microscopic examination. Of the 49 rabbits, 26 had histologic changes consistent with CCM. No common stressor for CCM was determined in affected rabbits. Animals were generally male, were 12-16-wk-old, and were found dead or had bloating, lethargy, and/or diarrhea. Those observed with clinical signs were euthanized and autopsied per the organization's standard operating procedures. Heart lesions consisted of various degrees of apical subendocardial myocardial degeneration and necrosis. Common non-cardiac lesions included pulmonary congestion and edema, hepatic congestion and centrilobular hepatocellular degeneration, and/or variable intestinal submucosal edema.

Adipocyte-Specific Laminin Alpha 4 Deletion Preserves Adipose Tissue Health despite Increasing Adiposity.

Laminins are heterotrimeric glycoproteins with structural and functional roles in basement membranes. The predominant laminin alpha chain found in adipocyte basement membranes is laminin α4 (LAMA4). Global LAMA4 deletion in mice leads to reduced adiposity and increased energy expenditure, but also results in vascular defects that complicate the interpretation of metabolic data. Here, we describe the generation and initial phenotypic analysis of an adipocyte-specific LAMA4 knockout mouse (Lama4AKO). We first performed an in-silico analysis to determine the degree to which laminin α4 was expressed in human and murine adipocytes. Next, male Lama4AKO and control mice were fed chow or high-fat diets and glucose tolerance was assessed along with serum insulin and leptin levels. Adipocyte area was measured in both epididymal and inguinal white adipose tissue (eWAT and iWAT, respectively), and eWAT was used for RNA-sequencing. We found that laminin α4 was highly expressed in human and murine adipocytes. Further, chow-fed Lama4AKO mice are like control mice in terms of body weight, body composition, and glucose tolerance, although they have larger eWAT adipocytes and lower insulin levels. High-fat-fed Lama4AKO mice are fatter and more glucose tolerant when compared to control mice. Transcriptionally, the eWAT of high-fat fed Lama4AKO mice resembles that of chow-fed control mice. We conclude from these findings that adipocyte-specific LAMA4 deletion is protective in an obesogenic environment, even though overall adiposity is increased.

Right Atrioventricular Valvular Dysplasia in a New Zealand White Rabbit.

A sixteen-week-old, male New Zealand White rabbit was euthanized following an acute onset of respiratory distress and cyanosis. On necropsy, the rabbit had marked right atrioventricular eccentric hypertrophy, absence or rudimentary presence of the septal leaflet of the right atrioventricular valve, focally extensive left ventricular infarction, diffuse hepatic chronic passive congestion, and diffuse pulmonary edema. To our knowledge, right atrioventricular valvular hypoplasia, dysplasia, or aplasia has not been previously described in rabbits.

Leucine acts in the brain to suppress food intake but does not function as a physiological signal of low dietary protein.

Intracerebroventricular injections of leucine are sufficient to suppress food intake, but it remains unclear whether brain leucine signaling represents a physiological signal of protein balance. We tested whether variations in dietary and circulating levels of leucine, or all three branched-chain amino acids (BCAAs), contribute to the detection of reduced dietary protein. Of the essential amino acids (EAAs) tested, only intracerebroventricular injection of leucine (10 µg) was sufficient to suppress food intake. Isocaloric low- (9% protein energy; LP) or normal- (18% protein energy) protein diets induced a divergence in food intake, with an increased consumption of LP beginning on day 2 and persisting throughout the study (P < 0.05). Circulating BCAA levels were reduced the day after LP diet exposure, but levels subsequently increased and normalized by day 4, despite persistent hyperphagia. Brain BCAA levels as measured by microdialysis on day 2 of diet exposure were reduced in LP rats, but this effect was most prominent postprandially. Despite these diet-induced changes in BCAA levels, reducing dietary leucine or total BCAAs independently from total protein was neither necessary nor sufficient to induce hyperphagia, while chronic infusion of EAAs into the brain of LP rats failed to consistently block LP-induced hyperphagia. Collectively, these data suggest that circulating BCAAs are transiently reduced by dietary protein restriction, but variations in dietary or brain BCAAs alone do not explain the hyperphagia induced by a low-protein diet.

Homeostatic regulation of protein intake: in search of a mechanism.

Free-living organisms must procure adequate nutrition by negotiating an environment in which both the quality and quantity of food vary markedly. Recent decades have seen marked progress in our understanding of neural regulation of feeding behavior. However, this progress has occurred largely in the context of energy intake, despite the fact that food intake is influenced by more than just the energy content of the diet. A large number of behavioral studies indicate that both the quantity and quality of dietary protein can markedly influence food intake. High-protein diets tend to reduce intake, low-protein diets tend to increase intake, and rodent models seem to self-select between diets in order to meet protein requirements and avoid diets that are imbalanced in amino acids. Recent work suggests that the amino acid leucine regulates food intake by altering mTOR and AMPK signaling in the hypothalamus, while activation of GCN2 within the anterior piriform cortex contributes to the detection and avoidance of amino acid-imbalanced diets. This review focuses on the role that these and other signaling systems may play in mediating the homeostatic regulation of protein balance, and in doing so, highlights our lack of knowledge regarding the physiological and neurobiological mechanisms that might underpin such a regulatory phenomenon.

Chronic exercise preserves renal structure and hemodynamics in spontaneously hypertensive rats.

AIMS: Exercise training (ExT) is a recommended adjunct to many pharmaceutical antihypertensive therapies. The effects of chronic ExT on the development of hypertension-induced renal injury remain unknown. We examined whether ExT would preserve renal hemodynamics and structure in the spontaneously hypertensive rat (SHR), and whether these effects were mediated by improved redox status and decreased inflammation. Normotensive WKY rats and SHR underwent moderate-intensity ExT for 16 weeks. One group of SHR animals was treated with hydralazine to investigate the pressure-dependent/independent effects of ExT. Acute renal clearance experiments were performed prior to sacrifice. Tissue free radical production rates were measured by electron paramagnetic resonance; gene and protein expression were measured by real time RT-PCR and Western blot or immunofluorescence, respectively. Plasma angiotensin II levels and kidney antioxidants were assessed. Training efficacy was assessed by citrate synthase activity assay in hind-limb muscle. RESULTS: ExT delayed hypertension, prevented oxidative stress and inflammation, preserved antioxidant status, prevented an increase in circulating AngII levels, and preserved renal hemodynamics and structure in SHR. In addition, exercise-induced effects, at least, in part, were found to be pressure-independent. INNOVATION: This study is the first to provide mechanistic evidence for the renoprotective benefits of ExT in a model of hypertension. Our results demonstrate that initiation of ExT in susceptible patients can delay the development of hypertension and provide renoprotection at the functional and ultrastructural level. CONCLUSION: Chronic ExT preserves renal hemodynamics and structure in SHR; these effects are partially mediated by improved redox status and decreased inflammation.

A blueberry-enriched diet attenuates nephropathy in a rat model of hypertension via reduction in oxidative stress.

OBJECTIVE AND BACKGROUND: To assess renoprotective effects of a blueberry-enriched diet in a rat model of hypertension. Oxidative stress (OS) appears to be involved in the development of hypertension and related renal injury. Pharmacological antioxidants can attenuate hypertension and hypertension-induced renal injury; however, attention has shifted recently to the therapeutic potential of natural products as antioxidants. Blueberries (BB) have among the highest antioxidant capacities of fruits and vegetables. METHODS AND RESULTS: Male spontaneously hypertensive rats received a BB-enriched diet (2% w/w) or an isocaloric control diet for 6 or 12 weeks or 2 days. Compared to controls, rats fed BB-enriched diet for 6 or 12 weeks exhibited lower blood pressure, improved glomerular filtration rate, and decreased renovascular resistance. As measured by electron paramagnetic resonance spectroscopy, significant decreases in total reactive oxygen species (ROS), peroxynitrite, and superoxide production rates were observed in kidney tissues in rats on long-term dietary treatment, consistent with reduced pathology and improved function. Additionally, measures of antioxidant status improved; specifically, renal glutathione and catalase activities increased markedly. Contrasted to these observations indicating reduced OS in the BB group after long-term feeding, similar measurements made in rats fed the same diet for only 2 days yielded evidence of increased OS; specifically, significant increases in total ROS, peroxynitrite, and superoxide production rates in all tissues (kidney, brain, and liver) assayed in BB-fed rats. These results were evidence of "hormesis" during brief exposure, which dissipated with time as indicated by enhanced levels of catalase in heart and liver of BB group. CONCLUSION: Long-term feeding of BB-enriched diet lowered blood pressure, preserved renal hemodynamics, and improved redox status in kidneys of hypertensive rats and concomitantly demonstrated the potential to delay or attenuate development of hypertension-induced renal injury, and these effects appear to be mediated by a short-term hormetic response.

Necrotizing Infiltrative Lipomatosis in a Miniature Zebu Bull (Bos primigenius indicus).

Lipomatosis is described in a miniature Zebu, Bos primigenius indicus, bull that died of perianesthetic complications. This is the first pathologic description of lipomatosis that we are aware of in this species and breed of cattle. Infiltration of multiple visceral organs is described and depicted along with comparison to previously published cases of lipomatosis in other breeds of cattle.

Electroporation advances in large animals.

In vivo electroporation-mediated gene therapy in large animals is gaining ground as one of the most important means for non-viral gene therapy. This review focuses on the novel aspects of reversible electroporation as applied to large animals, improvement of electroporation delivery technique, and development of electroporation-based vaccines. In regard to large animals, we have summarized the initial use of electroporation-mediated antineoplastic gene therapy in humans, vaccination in monkeys, reversing and preventing cachexia in dogs, and increases growth rate and piglet survival in pigs. Novel techniques incorporating electroporation, including ex vivo manipulations, electron avalanche transfection, and electrosonoporation illustrate evolving modifications. Specific alterations of electroporation parameters and DNA formulations along with ideas of enhancing gene transfection efficiency are provided in addition to a discussion of some of the current limitations of electroporation-mediated gene therapy.

Spinal lymphoma and pulmonary filariasis in a pet domestic rabbit (Oryctolagus cuniculus domesticus).

Spinal lymphoma and concurrent pulmonary filariasis are reported in a pet rabbit. The rabbit presented for pelvic limb paralysis resulting from extradural spinal lymphoma, presumably rising from the body of the sixth lumbar vertebra. The neoplasm was subsequently immunophenotyped as a B-cell lymphoma. Pulmonary filariasis was an incidental finding at necropsy.

Pituitary acidophil macroadenoma in a pygmy goat (Capra hircus hircus).

This report describes a pituitary acidophil macroadenoma in a goat. Antemortem clinical findings included hypothermia and rumen stasis. Clinicopathologic findings included refractory hypoglycemia, low total thyroxin and insulin concentrations, elevated bile acid concentration, and hyposthenuria. In addition to the pituitary macroadenoma, bilateral atrophy of the zona reticularis of the adrenal glands was observed histologically.

Tracheal hypoplasia with a discrete subaortic septal ridge in a Rottweiler puppy.

Concurrent tracheal hypoplasia and discrete subaortic stenosis are described in a 12-week-old Rottweiler puppy that presumably died of pulmonary edema. A brief literature review and comparison to previously published cases of tracheal hypoplasia in other breeds is presented along with a description of a subaortic septal ridge and comparison to the analogous condition in humans.

Comparison of methods for assay of fecal proteolytic activity.

Fecal proteolytic activity (FPA) in ten normal dogs was readily detected either calorimetrically using azocasein substrate or by radial enzyme diffusion into agar gels containing casein substrate. Daily FPA ranged from 17 to 207 azocasein units/g (ACUIG) or 4 to 18 mm of casein hydrolysis, while mean 3-day FPA ranged from 58 to 10 1 ACUIG or 7 to 15 mm. Studies of proteolytic activity remaining after treatment of fecal extracts with a specific trypsin inhibitor indicated that trypsin accounted for 0% to 71% of proteolytic activity. Proteolytic activity decreased steadily in fecal specimens stored at room temperature or above, but there was only slight loss in activity during storage for up to 5 days at 4 degrees C. Proteolytic activity was unaffected by repeated freezing and thawing and samples could be stored for long periods at -2 degrees C without noticeable loss of activity. It is concluded that assays of FPA using either azoprotein substrate or radial enzyme diffusion into agar gels containing casein substrate allow evaluation of exocrine pancreatic function in dogs, provided that several samples are tested. These methods are suitable for application in a variety of species.