Daily Rhythm of Lactate Dehydrogenase in Rat (Rattus norvegicus) Carrying a Per1-luciferase Transgene: Assessment on Serum and Liver

Veterinary Research Communications -     

Blood serum branched chain amino acids and tryptophan modifications in horses competing in long-distance rides of different length

During long-distance exercise, branched-chain amino acid (BCAA) catabolism could lead to an increase in the blood tryptophan/BCAA ratio and an early onset of 'central fatigue'. Based on these considerations, we studied the modifications of blood serum BCAA and tryptophan (Try) levels in 30 endurance horses competing in rides varying in distance from 20 to 72 km. From all horses, blood samples were drawn just before and just after the end of the ride. Samples were analysed for their leucine (Leu), valine (Val), isoleucine (Iso) and Try levels. Data were processed by anova, using sampling moment and ride as factors, and by LSD post hoc test. Significant differences were recorded among the different distance rides for Leu, Val, Iso, Try, Try/BCAA ratio; the same trend was recorded between samples taken at the start and the end of the race for Val and Leu. The main effect observed was an increase of BCAA levels for all rides, except the 72-km ride; for Try, a significant increase was present in all races, except the 50-km ride. The Try/BCAA ratio decreased in 20- and 50-km races and increased in the others. These data confirm that long-distance exercise involves a mobilization of BCAA. The utilization of BCAA seems to be important in prolonged exercise: in the 72-km ride, we observed a decrease in BCAA blood serum levels, while a major role of Try was indicated by its increase, resulting in a rise of the Try/BCAA ratio.     

Daily rhythm of salivary and serum urea concentration in sheep

Background  

In domestic animals many biochemical and physiological processes exhibit daily rhythmicity. The aim of the present study was to investigate the rhythmic pattern of salivary and serum urea concentrations in sheep.     

Central fatigue and nycthemeral change of serum tryptophan and serotonin in the athletic horse

Background  

The serotonergic system is associated with numerous brain functions, including the resetting of the mammalian circadian clock. The synthesis and metabolism of 5-HT in the brain increases in response to exercise and is correlated with high levels of blood-borne tryptophan (TRP). The present investigation was aimed at testing the existence of a daily rhythm of TRP and 5-HT in the blood of athletic horses.     

Daily rhythmicity in nutrient content of asinine milk

Asinine (donkey) milk has been proposed as an alternative to bovine (cow) milk for consumption by human infants who are allergic to bovine milk proteins. To expand the current knowledge of asinine lactation, we investigated daily rhythmicity in the concentration of major constituents of asinine milk. We observed no daily rhythmicity in somatic cell count and pH but observed robust rhythmicity in lipid, lactose, and protein content (robustness greater than 70%, p < 0.01). Lipid and lactose content peaked during the night, whereas protein content peaked during the day. Lipid content of asinine milk was lower than that of human milk, and asinine milk resembled human milk better than bovine milk regarding sugar and protein content.     

A Comparison of Daily Rhythm of Creatinine and Creatine Kinase in the Sedentary and Athlete Horse

The goal of this study was to investigate the existence of a daily rhythm of creatinine or creatine kinase (CK) and the influence of physical exercise on these rhythms. Blood samples from 20 Sella Italiana horses were collected every 4 hours for 48 consecutive hours via an intravenous cannula inserted into the jugular vein. The horses were divided into two equal groups (Sedentary [S] and Athlete [A]). After 2 weeks of rest, athletes (AR) were subjected again to sample collection every 4 hours for 48 consecutive hours, and sera creatinine and CK were assessed. Statistical analysis of the data was performed by one-way repeated analysis of variance (ANOVA), paired Student's t-test, unpaired Student's t-test, and analysis of single cosinor method. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. In all horses, we found a highly significant effect of time of the day on the studied parameters (P < .01). Statistically significant differences were observed for mean serum CK values between sedentary and athlete horses. The application of the periodic model showed a daily rhythm of the parameters studied in all experimental conditions. The results obtained during the experimental period indicated a daily rhythm of creatinine and CK in sedentary and athlete horses and also indicated that physical exercise was able to influence amplitude, acrophase, and robustness of the creatinine and CK circadian rhythm.     

Daily rhythms of blood pressure, heart rate, and body temperature in fed and fasted male dogs

Daily or circadian rhythmicity in physiological processes has been described in a large number of species of birds and mammals. However, in dogs, most studies have either failed to detect rhythmicity or have found that rhythmicity reflects merely an acute exogenous effect of feeding rather than an autonomous rhythmic process. In the present study, we investigated the rhythmicity of body temperature, blood pressure, and heart rate in dogs fed daily as well as in dogs deprived of food for 60 h. Our results document clear rhythmicity in all three parameters and demonstrate that the rhythmicity is independent of the feeding schedule. The failure of various previous investigations to document daily rhythmicity in dogs is probably due to lack of experimental rigour rather than to weakness of daily rhythmicity in dogs.     

Incidence of positive heartworm antibody and antigen tests at IDEXX Laboratories: trends and potential impact on feline heartworm awareness and prevention

Data from the IDEXX Laboratories Reference Laboratory Network were retrospectively examined for feline heartworm testing trends in testing frequency, geographic bias, and prevalence for the years 2000--2006. Examination of the data supports the commonly held view that veterinarians do not embrace heartworm disease testing or prevention in cats to the same degree they do in dogs. Despite significant awareness and adoption of heartworm testing and prevention in dogs, we hypothesized that heartworm testing rates are lower for cats than for dogs despite a significant prevalence of feline infection. This is important because a perceived low rate of infection in cats is likely to manifest in a low adoption of testing and prevention. In reality, the overall feline heartworm antigen-positive rate is significant--on average 0.9% over the period studied--and in some regions was estimated to be as high as 4.6%. This compares with an average canine heartworm prevalence rate of 1.2%, a feline leukemia virus prevalence of 1.9%, and a feline immunodeficiency prevalence of 1.0%. Based on the low rate of testing and these prevalence rates, practitioners are routinely missing cases of adult feline heartworm infections and the recently defined heartworm-associated respiratory disease (H.A.R.D). Increased antigen testing would result in detection of a significant number of positive cases. In addition, this population of infected cats would represent the "tip of the iceberg" relative to the greater number of cats that have early infection or are at risk for infection.