The influence of sex on biochemical markers of bone turnover in dogs.

Biochemical markers of bone turnover have been shown to be useful as inexpensive and noninvasive tools for monitoring skeletal health. The reference range for bone markers in dogs has been set by different age groups. However, other sources of biological variations were not fully investigated in dogs. To explore whether sex influences the interpretation of bone marker data we examined serum bone markers in 33 male and 25 female dogs. The bone markers selected for this study were: bone alkaline phosphatase (BALP) and osteocalcin (OC) as indicators of bone formation, and C-terminal telopeptide (CTx) of type I collagen as marker of bone resorption. All concentrations of bone markers were lower, but still within the reference range reported for dogs. We found statistically significant differences of the median OC and CTx serum concentrations between males and females. The results of this study suggest that there are sex differences in biochemical markers of bone turnover in dogs which should be considered in interpretation of bone marker data.

Serum platelet-activating factor acetylhydrolase and paraoxonase-1 activity in horses infected with Leptospira spp.

The aim of the study was to investigate the effect of infection with Leptospira spp. in horses on activities of platelet-activating factor acetylhydrolase (PAF-AH) and paraoxonase-1 (PON1) considering the anti-inflammatory/anti-oxidative properties of both enzymes. A total of 63 sport and leisure horses' sera were chosen among those routinely serologically examined on leptospirosis during the year 2009 in Croatia. Sera were divided into three groups according to the estimated level of antibody titre against Leptospira spp; group 1: sera serologically negative to leptospirosis (antibody titre<50) (n=21); group 2: sera with residual or anamnestic antibody titre (50-200) (n=23); group 3: sera with high antibody titre (≥1600) indicating recent Leptospira infection (n=19). Serum PAF-AH and PON1 activity was not significantly different between investigated groups (p>0.05). There were no statistical differences in lipid status parameters (p>0.05) among study groups as well. However, significant positive correlations (p<0.05) of PAF-AH and PON1 with total cholesterol and HDL-C were found. Results may indicate low levels of systemic inflammatory response and oxidative stress in horses with subclinical leptospirosis. Further studies with clinically manifested disease are needed to elucidate the potential role of PAF-AH and PON1 as prognostic markers of the leptospirosis outcome.

Effect of splenectomy and autologous spleen transplantation on the serum platelet-activating factor acetylhydrolase (PAF-AH) activity and acute phase response (APR) in a porcine model.

The aim of this study was to evaluate the inflammatory response after total splenectomy and spleen autotransplantation in a porcine model by measuring serum platelet-activating factor acetylhydrolase activity, C-reactive protein and albumin concentrations. Nineteen piglets were used in the experiment. After induction of anesthesia, animals were randomly divided into three groups: sham-operation with spleens intact (n = 6), total splenectomy (n = 6), and splenic autotransplantation (n = 7) with small fragments of the spleen autotransplanted into the greater omentum. The blood samples were taken just before surgery and on day 1st, 5th, 12th, 26th and 40th postoperatively. PAF-AH activity, CRP and albumin concentrations were assayed in the sera. After total splenectomy, PAF-AH activity was significantly increased on day 5th, while there was no significant increase after spleen autotransplantation or the sham-operation. CRP was significantly increased after surgery in all experimental groups. Albumin was significantly decreased after surgery from day 5th until day 40th in splenectomized and autotransplanted pigs. Increased PAF-AH activity after splenectomy and spleen autotransplantation might be attributed to inflammatory conditions due to the loss of splenic tissue and trauma. Time-course increase of CRP, in all groups after surgery suggests post-injury inflammatory response due to tissue lesion during operation.

Bovine platelet-activating factor acetylhydrolase (PAF-AH) activity related to fertility.

Plasma platelet-activating factor acetylhydrolase (PAF-AH), the enzyme characterized by the association with plasma lipoproteins, degrades platelet-activating factor (PAF) as well as PAF-like oxidatively fragmented phospholipids produced during oxidative stress. Apart from pro-inflammatory properties, PAF is also related to reproductive processes and successful fertility. In order to get a better insight into the involvement of PAF-AH in the fertility of cows, the aim of the study was to determine the PAF-AH activity as well as the C-reactive protein, cholesterol and high density lipoprotein-cholesterol (HDL-C) in the serum of dairy cows throughout the pregnancy and lactation, as well as in infertile cows. The results showed that serum PAF-AH activity changes throughout pregnancy and lactation with a lower level during periparturient period. It is also found higher PAF-AH activity in lactating cows with reproductive disorders compared to high lactating cows without reproductive disorders. Strong correlation between PAF-AH activity and HDL-C concentration indicates that HDL could have considerable influence on PAF-AH activity in bovine plasma. CRP concentration was also lower during transition period suggesting that lactation might stimulate CRP synthesis in bovine. A higher CRP concentration in cows with reproductive disorders compared to fertile cows at the peak of lactation, demonstrates that milk production is not the only factor influencing CRP in cows. A significant correlation between PAF-AH activity and CRP level shows that both parameters could be influenced by reproductive status of dairy cows.