Pharmacological treatments and risks for the food chain

Veterinarians play a pivotal role in public health control, in particular in the management of risks deriving from pharmacological treatments of food-producing animals. Veterinary medicinal products can represent a risk for animal health and welfare (side effects, decreased efficacy), for farmers and practitioners administering the drug, for consumers of food of animal origin (presence of residues, occurrence of antibiotic resistance) and for the environment. According to pending European guidelines, risk management starts from marketing authorisation that must be based on risk evaluation and can be denied when the risk/benefit ratio is not favourable considering the advantages for animal health and welfare and for safety of consumers. Veterinarians can prevent and control risks by using correct pharmacological criteria to choose and administer medicinal products and undertaking risk-based inspection of residues of drugs in food of animal origin. Moreover, a major tool for veterinarians to prevent and control drug-borne risk is "pharmacovigilance". Risks for the environment are usually assessed during the pre-marketing approval process, however veterinarians, as risk managers, should educate farmers about correct drug handling and disposal, and periodically verify that suggested measures are applied.     

Characterization of alpha-adrenoceptor subtypes in smooth muscle of equine ileum

OBJECTIVE: To determine the concentration and binding characteristics of alpha-adrenoceptor subtypes in smooth muscle cell membranes of equine ileum. SAMPLE POPULATION: Segments of longitudinal and circular smooth muscle from the ileum of 8 male and 8 female adult horses. PROCEDURE: Distribution of alpha-adrenoceptor subtypes was assessed by use of radioligand binding assays incorporating [3H]-prazosin and [3H]-rauwolscine, highly selective alpha1- and alpha2-adrenoceptor antagonists, respectively. Characterization of adrenoceptor subtypes was performed by use of binding inhibition assays. RESULTS: On the basis of binding affinity for specific radioligands, low- and high-affinity alpha1- and alpha2-adrenoceptors were detected. Concentration of low-affinity alpha2-adrenoceptors was significantly greater in male horses, compared with females. Competition studies confirmed the specificity of the radioligands used in the binding assays. Alpha1-adrenoceptors of both subtypes in male and female horses had a higher affinity for prazosin than phentolamine, whereas yohimbine did not compete with the radioligand for binding. For alpha2-adrenoceptors regardless of subtype, potency of inhibition elicited by each drug varied between sexes. In males, yohimbine was a more potent inhibitor than phentolamine, which was more potent than prazosin. In females, yohimbine was more potent than prazosin, which was more potent than phentolamine. CONCLUSIONS AND CLINICAL RELEVANCE: High- and low-affinity alpha1- and alpha2-adrenoceptors were detected in smooth muscle of equine ileum. Because alpha-adrenoceptor subtypes, particularly alpha2-adrenoceptors, are involved in the regulation of gastrointestinal tract function, characterization of these receptors may represent the basis for development of new therapeutic strategies for the control of gastrointestinal disturbances in horses.     

Effects of competition on acute phase proteins and lymphocyte subpopulations – oxidative stress markers in eventing horses

The aim of the study was to evaluate markers of the acute phase response (APR) in eventing horses by measuring acute phase proteins (APP) (haptoglobin, Hp, and serum amyloid A, SAA), lysozyme, protein adducts such as pentosidine‐like adducts (PENT), malondialdehyde adducts (MDA), hydroxynonenal adducts (HNE) and total advanced glycation/glycoxidation end products (AGEs), complete blood count and lymphocyte subpopulations (CD4+, CD8+ and CD21+) both at rest and at the end of an eventing competition. Blood samples were collected from eight Warmblood horses (medium age 10 ± 3) during an official national 2‐day event competition at rest (R) and 10 min after the arrival of the cross‐country test on the second day. Exercise caused a significant increase in red blood cell number, haemoglobin, packed cell volume, neutrophils, white blood cell and lymphocyte number; however, these values remained within the normal range. The CD4+ and CD8+ cells significantly increased, whereas the CD21+ lymphocytes decreased; a significant increase in serum SAA, lysozyme and protein carbonyl derivates was also observed. Two‐day event causes significant changes in APR markers such as lysozyme, protein carbonyl derivates (HNE, AGEs, PENT) and lymphocyte subpopulations. The data support the hypothesis that 2‐day event may alter significantly APR markers. Limitations of the study were the relatively small sample size and sampling time conditioned by the official regulations of the event. Therefore, further studies are needed to investigate the time required for recovery to basal values in order to define the possible effects on the immune function of the athlete horse.     

Concentrations of platelet α2-adrenoceptors,lymphocyte muscarinic receptors,and blood monoamines in dogs (Canis familiaris) affected by canine cognitive dysfunction syndrome

Canine cognitive dysfunction syndrome (CDS) is a neurodegenerative disorder of aged dogs characterized by a progressive decline in cognitive function. In humans and laboratory animals, a variety of neurotransmitter abnormalities have been described in patients affected by age-related dementia. Specifically, the regulatory role of the catecholaminergic, serotonergic, and cholinergic systems has been outlined. The aim of the present study was to measure blood monoamine levels, platelet α₂-adrenergic receptors, and lymphocyte muscarinic receptors in healthy adult and aged dogs and in dogs affected by canine cognitive dysfunction. Based on clinical and behavioral examination, 40 dogs were divided into 3 groups: healthy adults (n = 14), aged dogs (n = 17), and aged dogs affected by canine cognitive dysfunction (n = 9). A significant reduction in plasma levels of norepinephrine and dopamine was observed both in aged dogs (0.16 ± 0.02 ng/mL, P < 0.01; 0.11 ± 02 ng/mL, P < 0.01, respectively) and in CDS dogs (0.14 ± 0.03 ng/mL, P < 0.05; 0.10 ± 00.005 ng/mL, P < 0.01, respectively) compared with adults (0.29 ± 0.04 ng/mL and 0.15 ± 0.02 ng/mL, respectively). No significant differences were observed among groups for α₂-adrenergic receptor concentrations. Canine lymphocytes express 2 distinct classes of muscarinic receptors, characterized by high (HA) and low affinity (LA) for [³H]-N-methyl-scopolamine. A significant age-dependent decrease in HA muscarinic receptors was observed. However, no differences were found between aged dogs (87.65 ± 11.08 sites/cell × 10²) and in CDS dogs (90.17 ± 6.75 sites/cell × 10² ) for HA muscarinic receptor concentrations. As far as LA muscarinic receptors are concerned, CDS dogs showed a significant increase (393.48 ± 63 sites/cell × 10²; P < 0.05) with respect to healthy adult dogs (188.84 ± 16.50 sites/cell × 10²). Our results suggest that the reduction in HA muscarinic receptor-binding sites could be representative of the physiological aging process, whereas the increase in lymphocyte LA muscarinic receptor levels could be related to the cognitive decline.     

Ensemble asteroseismology of solar-type stars with the NASA Kepler mission

In addition to its search for extrasolar planets, the NASA Kepler mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solar-type stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius, and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy.