Testicular hyperthermia reduces testosterone concentrations and alters gene expression in testes of Nelore bulls.

Increased testicular temperature reduces sperm motility, morphology and fertility. Our objectives were to characterize effects of testicular hyperthermia (scrotal insulation) on acute testosterone concentrations and gene expression in Bos indicus testes. Nelore bulls (n = 20), ∼27 mo of age, 375 kg, scrotal circumference >31 cm, with ≥30% motile sperm, were allocated into four groups (n = 5/group): non-insulated (Control) and insulation removed after 12, 24, or 48 h. Immediately after insulation, intratesticular temperatures (needle thermocouples) were coolest in Control bulls and warmest in 48-h bulls (mean ± SEM, 35.28 ± 0.31 vs 38.62 ± 0.57 °C, P < 0.05). Bulls were castrated and testes recovered. Testicular testosterone concentrations were higher in Control versus 48-h bulls (3119 ± 973.3 and 295.5 ± 122.8 ng/g of tissue, respectively, P < 0.05). Total RNA was extracted, reverse transcribed and RT-qPCR done. For STAR, mRNA abundance decreased from Control to 48 h (1.14 + 0.32 vs 0.32 + 0.5, P < 0.05). For BCL2, expression decreased from Control to 24 h (1.00 + 0.07 vs 0.70 + 0.12, P < 0.05), but then rebounded. In addition, GPX1 had a 70% increase (P < 0.05) at 48 h, whereas HSP70 had a 34-fold increase (P < 0.05) at 12 h and 2- and 14-fold increases (P < 0.05) at 24 and 48 h, respectively. HSF1, BAX, P53 and CASP 8 remained unchanged. Downregulation of STAR, critical in androgen production, was consistent with reduced testosterone concentrations, whereas increased GPX1 enhanced testicular antioxidative capability. Huge increases in HSP70 conferred protection again apoptosis and cell destruction, whereas reduced BCL2 promoted apoptosis. These findings provided novel insights into acute tissue responses (testosterone and gene activity) to testicular hyperthermia in B. indicus bulls.

Short-term testicular warming under anesthesia causes similar increases in testicular blood flow in Bos taurus versus Bos indicus bulls, but no apparent hypoxia.

Bull testes must be 4-5 °C below body temperature, with testicular warming more likely to cause poor-quality sperm in Bos taurus (European/British) versus Bos indicus (Indian/zebu) bulls. Despite a long-standing dogma that testicular hyperthermia causes hypoxia, we reported that increasing testicular temperature in bulls and rams enhanced testicular blood flow and O2 delivery/uptake, without hypoxia. Our objective was to determine effects of short-term testicular hyperthermia on testicular blood flow, O2 delivery and uptake and evidence of testicular hypoxia in pubertal Angus (B. taurus) and Nelore (B. indicus) bulls (nine per breed) under isoflurane anesthesia. As testes were warmed from 34 to 40 °C, there were increases (P < 0.0001, but no breed effects) in testicular blood flow (mean ± SEM, 9.59 ± 0.10 vs 17.67 ± 0.29 mL/min/100 g, respectively), O2 delivery (1.79 ± 0.06 vs 3.44 ± 0.11 mL O2/min/100 g) and O2 consumption (0.69 ± 0.07 vs 1.25 ± 0.54 mL O2/min/100 g), but no indications of testicular hypoxia. Hypotheses that: 1) both breeds increase testicular blood flow in response to testicular warming; and 2) neither breed has testicular hypoxia, were supported; however, the hypothesis that the relative increase in blood flow is greater in Angus versus Nelore was not supported. Although these were short-term increases in testicular temperature in anesthetized bulls, results did not support the long-standing dogma that increased testicular temperature does not increase testicular blood flow and an ensuing hypoxia is responsible for decreases in motile, morphologically normal and fertile sperm.

Effects of 6% Tetrastarch and Lactated Ringer's Solution on Extravascular Lung Water and Markers of Acute Renal Injury in Hemorrhaged, Isoflurane-Anesthetized Healthy Dogs.

BACKGROUND: Tetrastarch can cause acute kidney injury (AKI) in humans with sepsis, but less likely to result in tissue edema than lactated Ringer's solution (LRS). OBJECTIVES: Compare effects of volume replacement (VR) with LRS and 6% tetrastarch solution (TS) on extravascular lung water (EVLW) and markers of AKI in hemorrhaged dogs. ANIMALS: Six healthy English Pointer dogs (19.7-35.3 kg). METHODS: Prospective crossover study. Animals underwent anesthesia without hemorrhage (Control). Two weeks later, dogs hemorrhaged under anesthesia on 2 occasions (8-week washout intervals) and randomly received VR with LRS or TS at 3 : 1 or 1 : 1 of shed blood, respectively. Anesthesia was maintained until 4 hour after VR for EVLW measurements derived from transpulmonary thermodilution cardiac output. Neutrophil gelatinase-associated lipocalin (NGAL) and creatinine concentrations in plasma and urine were measured until 72 hour after VR. RESULTS: The EVLW index (mL/kg) was lower at 1 hour after TS (10.0 ± 1.9) in comparison with controls (11.9 ± 3.4, P = 0.04), and at 4 hour after TS (9.7 ± 1.9) in comparison with LRS (11.8 ± 2.7, P = 0.03). Arterial oxygen partial pressure-to-inspired oxygen fraction ratio did not differ among treatments from 0.5 to 4 hour after VR. Urine NGAL/creatinine ratio did not differ among treatments and remained below threshold for AKI (120,000 pg/mg). CONCLUSIONS AND CLINICAL IMPORTANCE: Although TS causes less EVLW accumulation than LRS, neither fluid produced evidence of lung edema (impaired oxygenation). Both fluids appear not to cause AKI when used for VR after hemorrhage in healthy nonseptic dogs.

Comparison of Transpulmonary Thermodilution and Calibrated Pulse Contour Analysis with Pulmonary Artery Thermodilution Cardiac Output Measurements in Anesthetized Dogs.

BACKGROUND: Transpulmonary thermodilution (TPTDCO ) and calibrated pulse contour analysis (PCACO ) are alternatives to pulmonary artery thermodilution cardiac output (PATDCO ) measurement. HYPOTHESIS: Ten mL of ice-cold thermal indicator (TI10 ) would improve the agreement and trending ability between TPTDCO and PATDCO compared to 5 mL of indicator (TI5 ) (Phase-1). The agreement and TA between PCACO and PATDCO would be poor during changes in systemic vascular resistance (SVR) (Phase-2). ANIMALS: Eight clinically normal dogs (20.8-31.5 kg). METHODS: Prospective, experimental study. Simultaneous TPTDCO and PATDCO (averaged from 3 repetitions) using TI5 and TI10 were obtained during isoflurane anesthesia combined or not with remifentanil or dobutamine (Phase-1). Triplicate PCACO and PATDCO measurements were recorded during phenylephrine-induced vasoconstriction and nitroprusside-induced vasodilation (Phase-2). RESULTS: Mean bias (limits of agreement: LOA) (L/min), percentage bias (PB), and percentage error (PE) were 0.62 (-0.11 to 1.35), 16%, and 19% for TI5 ; and 0.33 (-0.25 to 0.91), 9%, and 16% for TI10 . Mean bias (LOA), PB, and PE were 0.22 (-0.63 to 1.07), 6%, and 23% during phenylephrine; and 2.12 (0.70-3.55), 43%, and 29% during nitroprusside. Mean angular bias (radial LOA) values were 2° (-10° to 14°) and -1° (-9° to 6°) for TI5 and TI10 , respectively (Phase-1), and 38° (5°-71°) (Phase-2). CONCLUSIONS AND CLINICAL IMPORTANCE: Although TI10 slightly improves the agreement and trending ability between TPTDCO and PATDCO in comparison to TI5 , both volumes can be used for TPTDCO in replacement of PATDCO . Vasodilation worsens the agreement between PCACO and PATDCO . Because of PCACO 's poor agreement and trending ability with PATDCO during SVR changes, this method has limited clinical application.

Effects of muscarinic receptor antagonists on acetylcholine-induced contractions of jejunal smooth muscle in horses.

This study investigated the effects of a muscarinic type 1 (M(1)), 2 (M(2)), and 3 (M(3)) antagonists (4-DAMP, pirenzepine, and methoctramine, respectively) on acetylcholine (Ach)-induced contractions of longitudinal jejunal muscle strips of horses. Strips were irrigated with Krebs-Henseleit solution gassed with 95% O(2) and 5% CO(2), and the developed tension in response to Ach was recorded before and after incubation with increasing concentrations of 4-DAMP (10(-8)-10(-6) M), pirenzepine (10(-6)-10(-4) M), and methoctramine (10(-5)-10(-3) M). When competitive antagonism was characterized, the affinity constant (pA(2)) was calculated by Schild plots. A parallel rightward shift in the concentration-response curves was observed after 4-DAMP and pirenzepine. Methoctramine presented a dual effect on the concentration-response curves: lower concentrations induced a parallel rightward shift without altering the maximum intensity of contraction (E(max)), while the highest concentration increased slope of the concentration-response curve and increased E(max). The pA(2) for 4-DAMP and pirenzepine was 9.18 and 7.13, respectively. Acetylcholine-induced contractions of longitudinal jejunal smooth muscle are mediated mainly via M(3) receptors. The complex role of M(2) receptors in jejunal smooth muscle contractions was evident because methoctramine potentiated the contractile response to higher doses of Ach.

Comparative study between atropine and hyoscine-N-butylbromide for reversal of detomidine induced bradycardia in horses.

REASONS FOR PERFORMING STUDY: Bradycardia may be implicated as a cause of cardiovascular instability during anaesthesia. HYPOTHESIS: Hyoscine would induce positive chronotropism of shorter duration than atropine, without adversely impairing intestinal motility in detomidine sedated horses. METHODS: Ten minutes after detomidine (0.02 mg/kg bwt, i.v.), physiological saline (control), atropine (0.02 mg/kg bwt) or hyoscine (0.2 mg/kg bwt) were randomly administered i.v. to 6 horses, allowing one week intervals between treatments. Investigators blinded to the treatments monitored cardiopulmonary data and intestinal auscultation for 90 min and 24 h after detomidine, respectively. Gastrointestinal transit was assessed for 96 h via chromium detection in dry faeces. RESULTS: Detomidine significantly decreased heart rate (HR) and cardiac index (CI) from baseline for 30 and 60 min, respectively (control). Mean ± s.d. HR increased significantly 5 min after atropine (79 ± 5 beats/min) and hyoscine (75 ± 8 beats/min). After this time, HR was significantly higher after atropine in comparison to other treatments, while hyoscine resulted in intermediate values (lower than atropine but higher than controls). Hyoscine and atropine resulted in significantly higher CI than controls for 5 and 20 min, respectively; but this effect coincided with significant hypertension (mean arterial pressures >180 mmHg). Auscultation scores decreased from baseline in all treatments. Time to return to auscultation scores ≥12 (medians) did not differ between hyoscine (4 h) and controls (4 h) but atropine resulted in significantly longer time (10 h). Atropine induced colic in one horse. Gastrointestinal transit times did not differ between treatments. CONCLUSION: Hyoscine is a shorter acting positive chronotropic agent than atropine, but does not potentiate the impairment in intestinal motility induced by detomidine. Because of severe hypertension, routine use of anticholinergics combined with detomidine is not recommended. POTENTIAL RELEVANCE: Hyoscine may represent an alternative to atropine for treating bradycardia.

Comparison of the cardio-respiratory effects of methadone and morphine in conscious dogs.

The effects of methadone and morphine were compared in conscious dogs. Six animals received morphine sulfate (1 mg/kg) or methadone hydrochloride (0.5 mg/kg [MET0.5] or 1.0 mg/kg [MET1.0]) intravenously (i.v.) in a randomized complete block design. Cardiopulmonary variables were recorded before (baseline), and for 120 min after drug administration. One outlier was not included in the statistical analysis for hemodynamic data. Morphine decreased heart rate (HR) compared to baseline from 30 to 120 min (-15% to -26%), while cardiac index (CI) was reduced only at 120 min (-19%). Greater and more prolonged reductions in HR (-32% to -46%) and in CI (-24% to -52%) were observed after MET1.0, while intermediate reductions were recorded after MET0.5 (-19 to -28% for HR and -17% to -27% for CI). The systemic vascular resistance index (SVRI) was increased after methadone; MET1.0 produced higher SVRI values than MET0.5 (maximum increases: 57% and 165% for MET0.5 and MET1.0, respectively). Compared to morphine, oxygen partial pressure (PaO(2)) was lower (-12% to -13%) at 5 min of methadone (0.5 and 1.0 mg/kg), while carbon dioxide partial pressure (PaCO(2)) did not change significantly. It was concluded that methadone induces cardiovascular changes that are dose-related and is a more potent cardiovascular depressant agent than morphine in conscious dogs.

Alterações do pH, da P O2 e da P CO2 arteriais e da concentração de lactato sangüíneo de cavalos da raça Arabe durante exercício em esteira de alta velocidade / Changes in arterial pH, P O2, P CO2 and blood lactate concentration in Arabian horses during exercise on a high-speed treadmill

Avaliaram-se as alterações do pH, da P O2 e da P CO2 do sangue arterial e da concentração de lactato sangüíneo de 11 cavalos adultos da raça Arabe, submetidos a exercício progressivo em esteira de alta velocidade. Antes do exercício, no intervalo dos 15 segundos finais de cada mudança de velocidade e aos 1, 3 e 5 minutos após o término do exercício foram coletadas amostras de sangue arterial e venoso para a mensuração dos gases sangüíneos e da concentração de lactato. O exercício resultou em diminuição do pH, da pressão parcial de O2 (P O2) e da pressão parcial de CO2 (P CO2). A concentração de lactato sangüíneo elevou-se exponencialmente a partir da velocidade de 8,0m/s até os momentos após término do exercício.

Changes in arterial blood pH, P O2 and P CO2, and blood lactate concentration in Arabian horses during exercise on a high-speed treadmill were investigated. Eleven horses were submitted to a conditioning period as well as to the incremental exercise test. The arterial and venous blood samples were obtained to evaluate the blood gas values and lactate concentration, prior to the beginning of the exercise, on the last 15 final seconds between every change of speed and at the 1, 3 and 5 minutes after the exercise. A decrease in pH, partial pressure of oxygen (P O2), and partial pressure of carbon dioxide (P CO2) and the blood lactate levels exponentially increase beyond the speed of 8m/s, during the incremental exercise test.

Effects of four anaesthetic protocols on the neurological and cardiorespiratory variables of puppies born by caesarean section.

Twenty-four bitches which had been in labour for less than 12 hours were randomly divided into four groups of six. They all received 0.5 mg/kg of chlorpromazine intravenously as premedication, followed 15 minutes later by either 8 mg/kg of thiopentone intravenously (group 1), 2 mg/kg of ketamine and 0.5 mg/kg of midazolam intravenously (group 2), 5 mg/kg of propofol intravenously (group 3), or 2.5 mg/kg of 2 per cent lidocaine with adrenaline and 0.625 mg/kg of 0.5 per cent bupivacaine with adrenaline epidurally (group 4). Except for group 4, the bitches were intubated and anaesthesia was maintained with enflurane. The puppies' heart and respiratory rates and their pain, sucking, anogenital, magnum and flexion reflexes were measured as they were removed from the uterus. The puppies' respiratory rate was higher after epidural anaesthesia. In general the puppies' neurological reflexes were most depressed after midazolam/ketamine, followed by thiopentone, propofol and epidural anaesthesia.

Avaliaçäo cardiocirculatória do sevofluorano como agente de manutençäo anestésica em cäes, em diferentes concentraçöes de oxigênio e óxido nitroso / Sevoflurane cardiocirculatory study in dog with different oxygen and nitrous oxide concentrations

Com o objetivo de avaliar as alteraçöes cardiocirculatórias resultantes da manutençäo anestésica com sevofluorano, três grupos de 10 cäes cada foram anestesiados por 60 minutos com fluxo diluente de 100 por cento de oxigênio (grupo 1), de 50 por cento de oxigênio e de óxido nitroso (grupo 2) ou 27 por cento de oxigênio e 63 por cento de óxido nitroso (grupo 3). A tranqüilizaçäo foi realizada com levomepromazina (0,5 mg/kg) e a induçäo com tiopental (12,5 mg/lg). A freqüência cardíaca apresentou elevaçäo significativa após a induçäo (P<0,05), mantendo-se mais alta que a basal, em todos os grupos, durante toda a anestesia. As variaçöes das pressöes arteriais sistólica, média e diastólica foram pouco significativas e mantiveram-se em todos os grupos dentro de valores aceitáveis para a espécie e a utilizaçäo do óxido nitroso näo interferiu nessa variaçäo. O sevofluorano demonstrou ser um bom agente de manutençäo anestésica em cäes, e a adiçäo de 63 por cento de óxido nitroso ao fluxo diluente de oxigênio reduziu a necessidade anestésica de maneira significativa

Tratamento alternativo de feridas de papilas mamárias de vacas através do emprego de membrana biológica (Biofill) / Alternative treatment in tits wounds in cows by using biological membrane (Biofill)

Neste trabalho, avaliou-se a evoluçäo cicatricial de feridas provocadas experimentalmente em papilas mamárias de 16 vacas näo lactentes, através do emprego de uma membrana biológica que substitui temporariamente a pele, comparando-a com tratamento à base de pomada epitelizante. Em cada animal, a membrana foi colocada na ferida da papila mamária anterior direita e o tratamento com pomada foi realizado na papila mamária posterior direita. Foram feitas observaçöes clínicas e análise histológica no 3§, 7§, 14§ e 28§ dias do pós-operatório. Das observaçöes realizadas, verificou-se que as papilas tratadas com a membrana biológica cicatrizaram com uma semana de antecedência, quando comparadas às controle (pomada epitelizante). A utilizaçäo da membrana biológica, permitiu ainda uma reduçäo na freqüência de curativos