Surgery of hepatic cysts in a cat.

A 2-year-old female Japanese domestic cat weighing 3.6 kg was presented due to marked abdominal distention and was diagnosed as hepatic cyst. The bile acid concentration of the hepatic cyst was as low as the serum bile acid concentration. The membrane of the cysts was excised from the edge of the compressed hepatic tissue and no other surgical manipulation was performed. This surgical procedure is simple and quick compared to hepatic lobectomy, however, it is necessary to evaluate the fluid of the cyst before performing this procedure.     

Effect of Illuminance Transition Rate on Survival of Juvenile Pacific Bluefin Tuna,Thunnus orientalis

To investigate the reason for the high mortality of cultured juvenile Pacific bluefin tuna (PBT), especially during land‐based culture, we examined the effect of the rate of light‐intensity change during the dawn period. Juvenile PBT kept in a natural light environment (control) were compared with those exposed to an artificially slowed change in light intensity during the dawn period (test group). For the test group, lamps, which were connected to automatic timers and placed above the rearing tank, were switched on from 0345 to 0515 h at 15‐min intervals. After 9 d, the survival rate of the test and control group was identical. Between Day 1 and Day 6, whole‐body cortisol levels were not different between groups. However, whole‐body glucose levels in the test group were significantly higher than those in the control group. Both groups displayed a diel rhythm in plasma cortisol concentration that peaked at 0300–0600 h. These results suggest that slowing the increase in light intensity during the dawn period did not improve survival and that low light intensity itself induces high mortality in cultured PBT juveniles.     

Effect of calcium ion on the thermal denaturation of subfragment-1 and rod regions of squid myosin upon the heating of myofibrils

Thermal inactivation of Ca²⁺ ATPase of squid myofibrils was significantly suppressed in the presence of Ca²⁺. Monomeric myosin content decreased much faster than Ca²⁺ ATPase inactivation in Ca medium, which was well explained by fast rod denaturation. In contrast, rod denaturation was slower than S-1 in EDTA medium. The decrease in monomeric myosin content was explained by faster S-1 denaturation. Comparing the S-1 and rod denaturation rates at a fixed temperature, it was concluded that S-1 denaturation was suppressed by Ca²⁺ whereas the rod denaturation was not. An unfolding experiment with isolated myosin rod confirmed that there was no stabilizing effect of Ca²⁺ on myosin rod. It was concluded that significant stabilization of the S-1 portion by Ca²⁺ generated the apparently different myosin denaturation patterns in the two media.     

Milking performance evaluation and factors affecting milking claw vacuum levels with flow simulator

Milking performance of milking machines that matches the production capability of dairy cows is important in reducing the risk of mastitis, particularly in high‐producing cows. This study used a simulated milking device to examine the milking performance of the milking system of 73 dairy farms and to analyze the factors affecting claw vacuum. Mean claw vacuum and range of fluctuation of claw vacuum (claw vacuum range) were measured at three different flow rates: 5.7, 7.6 and 8.7 kg/min. At the highest flow rate, only 16 farms (21.9%) met both standards of mean claw vacuum ≥35 kPa and claw vacuum range ≤ 7 kPa, showing that milking systems currently have poor milking performance. The factors affecting mean claw vacuum were claw type, milk‐meter and vacuum shut‐off device; the factor affecting claw vacuum range was claw type. Examination of the milking performance of the milking system using a simulated milking device allows an examination of the performance that can cope with high producing cows, indicating the possibility of reducing the risk of mastitis caused by inappropriate claw vacuum.     

Central injection of ketone body suppresses luteinizing hormone release via the catecholaminergic pathway in female rats

Ketosis is found in various pathophysiological conditions, including diabetes and starvation, that are accompanied by suppression of gonadal activity. The aim of the present study was to determine the role of ketone body in the brain in regulating pulsatile luteinizing hormone (LH) secretion in female rats. Injection of 3-hydroxybutyrate (3HB), a ketone body, into the fourth cerebroventricle (4V) induced suppression of pulsatile LH secretion in a dose-dependent manner in ovariectomized (OVX) rats with an estradiol (E2) implant producing diestrus plasma E2 levels. Plasma glucose and corticosterone levels increased immediately after the 4V 3HB injection, suggesting that the treatment caused a hunger response. The 3HB-induced suppression of LH pulses might be mediated by noradrenergic inputs to the hypothalamic paraventricular nucleus (PVN) because a local injection of α-methyl- p-tyrosine, a catecholamine synthesis inhibitor, into the PVN blocked 3HB-induced suppression of LH pulses and PVN noradrenaline release was increased by 4V 3HB injection in E2-primed OVX rats. These results suggest that ketone body sensed by a central energy sensor in the hindbrain may suppress gonadotropin release via noradrenergic inputs to the PVN under ketosis.     

Regression tree analysis of the relationship between the concentrations of antimicrobial components and the microbiota of normal milk from dairy cows

The purpose of this study was to determine the concentrations of antimicrobial components (immunoglobulin A (IgA), lactoferrin (LF), lingual antimicrobial peptide (LAP), and S100A7) in normal milk and their relation to host factors (Age, somatic cell count (SCC), days in milk, richness, and alpha diversity of the milk microbiota) in dairy cows using multivariate regression tree analyses, and to clarify how the milk microbiota is related to the obtained results. Thirty normal milk samples were collected from a commercial dairy farm in June 2020. The thresholds that predicted the concentration of each antimicrobial component in milk were obtained by regression tree analysis, and the beta-diversity of the milk microbiota composition between groups divided according to each threshold was compared by an analysis of similarities test. The IgA and LF concentrations were mainly predicted by the SCC (177,500 and 70,000 cells/ml, respectively), and the LAP and S100A7 concentrations were predicted by Age (29.667 and 40.3 months, respectively). No relationship was observed between the concentration of IgA, LAP, or S100A7 and the milk microbiota composition between the groups divided by the threshold for prediction, but the milk microbiota composition was significantly different between the groups divided by the threshold for predicting the LF concentration. Our results indicated that the LF concentration in normal milk may be associated with the milk microbiota composition.     

A rat model for the energetic regulation of gonadotropin secretion: role of the glucose-sensing mechanism in the brain

Energy availability has been considered to regulate gonadal activity by modulating the release of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) at various reproductive phases, such as lactation and puberty in domestic as well as wild animals. Experimental models with rats and sheep have demonstrated that fasting or glucoprivation suppresses pulsatile LH release. From those experiments, the information on energy deficiency is considered to be detected by specific central sensors and conveyed to the hypothalamus to regulate LH release as well as food intake. Noradrenergic neurons, originating in the medulla oblongata and projecting to the hypothalamic paraventricular nucleus (PVN), is reported to be one of the pathways mediating the response of LH release to energy deficiency. The other component is considered to be an energy-sensing mechanism in the brain. Glucose or other oxidizable fuels may function as a metabolic signal to regulate LH release. Previous studies suggest the presence of a glucose-sensing mechanism in the rat hindbrain. From our previous results in the rat, the ependymocytes lining the wall of the cerebroventricle could possibly serve as a glucose sensor to regulate GnRH/LH release. Greater understanding of the nature of the energy-sensing mechanism in the brain will contribute to the nutritional manipulation of reproductive performance in domestic animals in various conditions.     

A spontaneously occurring malignant ovarian Sertoli cell tumor in a young Sprague Dawley rat

Primary ovarian tumors are generally uncommon in rats used in toxicologic studies. A malignant Sertoli cell tumor was present in the ovary of a 19-week-old female Sprague Dawley rat. Macroscopically, the mass was white and firm, 10 × 13 × 17 mm in size, and located in the right ovary. Histopathologically, the mass was composed of nests of pleomorphic cells, which formed seminiferous-like tubules separated by a thin fibrovascular stroma. The tubules were lined by tumor cells, which had basally located nuclei and abundant eosinophilic and vacuolated cytoplasm. In some areas, the tumor cells were arranged in a retiform growth pattern, mimicking a rete testis/ovarii. Disseminated metastases to the surfaces of the mesentery, spleen and liver were also present. Immunohistochemically, many tumor cells were strongly positive for vimentin, estrogen receptor α and Ki 67. Some tumor cells were positive for pancytokeratin and inhibin α. These findings closely resemble those of an ovarian-derived human malignant Sertoli cell tumor. From our review of the literature, we believe this is the first report of a spontaneous malignant Sertoli cell tumor in the ovary of a young laboratory rat. This case might provide useful historical control information for rat toxicity studies.