Evaluation of the thermal property of bovine intramuscular adipose tissue using differential scanning calorimetry

The thermal property of bovine intramuscular adipose tissue (IAT) was evaluated using differential scanning calorimetry (DSC) and compared with the melting point temperature (MP) of the fat extract of IAT, which was measured using the slip point method. The beef samples were classified according to the beef marbling score (BMS). Beef with a high BMS contained less protein than that with middle or low BMS. Beef with a high BMS contained significantly more fat than that with a low BMS (P < 0.05). The endothermic point temperature (EP) of IAT, measured by DSC, was significantly higher than the MP of IAT fat (P < 0.05). The EP showed no significant difference among the three marbling grade groups. Although the MP was correlated with the monounsaturated fatty acids (MUFA) content of IAT (R² = 0.505), there was no correlation between the EP and the MUFA (R² = 0.040). However, the EP of IAT treated with collagenase was relatively highly correlated with the MP (R² = 0.655). Thus, these results suggested that DSC analysis would give us the practical thermal information regarding the melt‐in the‐mouth of beef such as the gelatinization of collagen, along with the melting of fat in IAT.     

Effects of medetomidine-midazolam,midazolambutorphanol, or acepromazine-butorphanol as premedicants for mask induction of anesthesia with sevoflurane in dogs

OBJECTIVE: To characterize the effects of medetomidine-midazolam, midazolam-butorphanol, or acepromazine-butorphanol as premedicants for mask induction of anesthesia with sevoflurane in dogs. ANIMALS: 10 healthy Beagles. PROCEDURE: The following premedicants were administered intramuscularly: medetomidine-midazolam (20 microg/kg and 0.3 mg/kg, respectively), midazolam-butorphanol (0.1 and 0.2 mg/kg, respectively), and acepromazine-butorphanol (0.05 and 0.2 mg/kg, respectively). Saline (0.9% NaCI) solution (0.1 ml/kg) was administered intramuscularly as a control. Anesthesia was induced in each dog with sevoflurane in a 100% O2 at a flow rate of 4 L/min developed by a facemask. Vaporizer settings were increased by 0.8% at 15-second intervals until the value corresponding to 4.8% sevoflurane was achieved. Time to onset and cessation of involuntary movements, loss of the palpebral reflex, negative response to tail-clamp stimulation, and endotracheal intubation were recorded, and the cardiopulmonary variables were measured. RESULTS: Mask induction with sevoflurane in dogs that received each premedicant resulted in a shorter induction time and milder changes in heart rate, mean arterial blood pressure, cardiac output, and respiratory rate, compared with mask induction without premedicants. Treatment with medetomidine-midazolam resulted in a shorter and smoother induction, compared with acepromazine-butorphanol or midazolam-butorphanol treatment, whereas the cardiovascular changes were greater. Cardiopulmonary variables of dogs during induction following treatment with acepromazine-butorphanol or midazolam-butorphanol were maintained close to the anesthetic maintenance values for sevoflurane, with the exception of mild hypotension that was observed in dogs following acepromazine-butorphanol treatment. CONCLUSION AND CLINICAL RELEVANCE: In dogs use of premedicants provides a smoother and better quality mask induction with sevoflurane.     

Developmental competence of cat oocytes from ovaries stored at various temperature for 24 h

We conducted two experiments to investigate the effects of storage temperature and period for cat ovaries on the meiotic and developmental competence of oocytes collected from the ovaries. In Experiment 1, ovaries were stored in physiological saline for 24 h at 4 C, 23-25 C, or 38 C (cold, room, and incubator temperature groups, respectively), and then oocytes were collected from the ovaries in each group. Morphologically intact oocytes were then selected and cultured in maturation medium for 24 h. Significantly more oocytes reached metaphase II (MII) in the cold temperature group (53.4%) than in the room and incubator temperature groups (20.0 and 2.4%, respectively). In Experiment 2, ovaries were stored in physiological saline at room temperature for 0, 6, 12 or 18 h, and then they were stored at 4 C (cold storage) until reaching a total storage period of 24 h. After storage of the ovaries, morphologically intact oocytes were matured, fertilized with frozen-thawed spermatozoa, and cultured in vitro. The rates of morphologically intact oocytes obtained from the ovaries stored at room temperature for 0, 6, 12 or 18 h were 35.3, 30.0, 26.4 and 14.7%, respectively, and the rates of intact oocytes that reached MII were 63.2, 36.4, 26.5 and 11.9%, respectively. The results suggested that the numbers of morphologically intact oocytes and intact oocytes that reached MII after in vitro maturation decrease gradually as the period of storage at room temperature before cold storage increases. Only oocytes from ovaries stored for 6 h developed to the blastocyst stage after in vitro maturation and fertilization when ovaries were stored at room temperature before cold storage. These results indicate that 24 h storage of ovaries at high temperatures (>23 C) decreases the meiotic competence of oocytes. The quality and developmental competence of oocytes are influenced by the length of storage at room temperature before cold storage.     

Adipocytes suppress differentiation of muscle cells in a co‐culture system

The development of adipose tissue in skeletal muscle is important for improving meat quality. However, it is still unclear how adipocytes grow in the proximity of muscle fibers. We hypothesized that adipocytes would suppress muscle cell growth so as to grow dominantly within muscle. In this study, we investigated the effect of adipocytes on the differentiation of muscle cells in a co‐culture system. The fusion index of C2C12 myoblasts co‐cultured with 3T3‐L1 adipocytes was significantly lower than that of the control. The expression of myogenin and myosin heavy chain in C2C12 muscle cells co‐cultured with 3T3‐L1 adipocytes was significantly lower than in the control. Furthermore, the expression of Atrogin‐1 and MuRF‐1 was higher in C2C12 muscle cells co‐cultured with 3T3‐L1 adipocytes than the control. These results suggest that 3T3‐L1 adipocytes suppress the differentiation of C2C12 myoblasts. In addition, 3T3‐L1 adipocytes induced the expression and secretion of IL‐6 in C2C12 muscle cells. The fusion index and myotube diameter were higher in C2C12 muscle cells co‐cultured with 3T3‐L1 cells in medium containing IL‐6‐neutralizing antibody than the control. Taken together, there is a possibility that adipocyte‐induced IL‐6 expression in muscle cells could be involved in the inhibition of muscle cell differentiation via autocrine.     

Pharmacokinetics of fentanyl after single intravenous injection and constant rate infusion in dogs

OBJECTIVE: To determine the plasma concentration and define the pharmacokinetic characteristics of fentanyl (10 microg kg(-1)) administered as a single intravenous (IV) injection followed by: (a) no further drug; or (b) a constant rate infusion (CRI) of fentanyl 10 microg kg(-1) hour(-1) lasting 1, 3 or 4 hours in dogs. Animals Fourteen healthy adult beagles (seven males and seven females). EXPERIMENTAL DESIGN: Randomized cross-over design. MATERIALS AND METHODS: Dogs were randomly assigned to four treatment groups. Drugs were administered to each dog in a randomized cross-over design with at least a 14-day washout interval between experiments. All dogs received an IV loading dose of fentanyl (10 microg kg(-1)). One group received no further fentanyl. In others, the loading dose was followed by a CRI of fentanyl (10 microg kg(-1) hour(-1)) for 1, 3 or 4 hours. Blood samples were collected and plasma fentanyl concentrations determined using high-performance liquid chromatography-mass spectrometry. Plasma pharmacokinetic estimates were obtained by plotting plasma concentrations versus time data and by fitting the change in concentration to a pharmacokinetic model, using a purpose-built program written by the Graduate School of Pharmaceutical Sciences (Kyoto University) in Visual Basic (VBA) on Excel (Microsoft Corporation). RESULTS: Plasma fentanyl concentration decreased rapidly after single IV injection: the plasma concentration-time curve best fitted a two-compartment model. Pharmacokinetic variables for IV injection were characterized by a short distribution half-time (t1/2alpha was 4.5 minutes), a relatively long elimination half time (t1/2beta was 45.7 minutes), a large volume of distribution (approximately 5 L kg(-1)) and high total body clearance (77.9 mL minute(-1) kg(-1)). Stable plasma fentanyl levels were obtained in all CRI groups although pharmacokinetic variables were influenced by the duration of administration. CONCLUSIONS AND CLINICAL RELEVANCE: While this study clarified the pharmacokinetic features of rapid IV fentanyl injection and CRI in dogs, the plasma concentration achieving analgesia was not and so further research is needed. Further studies on the effects of other sedatives and/or anaesthetics on fentanyl's disposition are also required as the drug is commonly used with other agents.     

Retinoid receptors and the induction of apoptosis in canine osteosarcoma cells

Retinoids, all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid (9-cis-RA), induced morphological changes and apoptosis-like cell death characterized by cell shrinkage, chromatin condensation and nuclear disintegration in three canine osteosarcoma cells, OOS, HOS and POS, at a concentration of 10(-5) M. Both retinoid receptors, RARs and RXRs, were identified in these cells. 9-cis-RA bound to both the RXRs and the RARs, whereas ATRA bound to only the RARs in these cells. Those results indicate that the induction of apoptosis in canine osteosarcoma cells may be mediated by the specific control of RARs and RXRs.     

Effects of perineural capsaicin treatment on cardiopulmonary reflexes elicited by laryngeal instillations of capsaicin and distilled water in sevoflurane-anesthetized dogs

The aim of this study was to determine the effect of perineural capsaicin (CAPS) treatment on cardiopulmonary reflexes elicited by topical laryngeal instillation of CAPS and distilled water (DW) in sevoflurane-anesthetized dogs. Cardiopulmonary reflexes elicited by CAPS (10 microg/ml, 10 ml) were attenuated by perineural CAPS treatment to the superior laryngeal nerves (SLNs) (P<0.05), whereas those by DW (10 ml) remained unaffected (P>0.05). The reflex responses to DW that remained even after the perineural CAPS treatment were eliminated by laryngeal anesthesia with lidocaine. These results suggest that cardiopulmonary reflexes from the laryngeal mucosa elicited by CAPS instillation can be blocked by perineural CAPS treatment to the SLNs, which may result from inhibition of the laryngeal CAPS-sensitive C-fiber afferents.     

Effect of all-trans and 9-cis retinoic acid on growth and metastasis of xenotransplanted canine osteosarcoma cells in athymic mice

OBJECTIVE: To determine effects of all-trans and 9-cis retinoic acid (RA) on tumor growth and metastatic ability of canine osteosarcoma cells transplanted into athymic (nude) mice. ANIMALS: Forty-five 5-week-old female BALB/c nude mice. PROCEDURE: 1 X 10(7) POS osteosarcoma cells were transplanted subcutaneously into the intrascapular region of mice. All-trans RA (3 or 30 microg/kg of body weight in 0.1 ml of sesame oil), 9-cis RA (3 or 30 mg/kg in 0.1 ml of sesame oil), or sesame oil (0.1 ml; control treatment) were administered intragastrically 5 d/wk for 4 weeks beginning 3 days after transplantation (n = 4 mice/group) or after formation of a palpable tumor (5 mice/group). Tumor weight was estimated weekly by measuring tumor length and width, and retinoid toxic effects were evaluated daily. Two weeks after the final treatment, mice were euthanatized, and number of mice with pulmonary metastases was determined. RESULTS: Adverse treatment effects were not detected. Tumor weight was less in mice treated with either dose of 9-cis RA than in control mice, although this difference was not significant. Treatment with 30 mg of 9-cis RA/kg initiated after tumor formation significantly reduced the incidence of pulmonary metastasis, compared with the control group. CONCLUSIONS AND CLINICAL RELEVANCE: 9-cis RA decreased the incidence of pulmonary metastasis in nude mice transplanted with canine osteosarcoma cells and may be a potential adjunct therapy for treatment of osteosarcoma in dogs.