Effects of cow age and pregnancy on Bartonella infection in a herd of dairy cattle

Bartonella spp. are small hemotropic bacteria infecting mammals. Four Bartonella species have been recently described in cattle and wild ruminants. To date, the biology and possible pathogenic role of Bartonella species isolated from ruminants are poorly understood. Therefore, a dairy herd of 448 cows and heifers was surveyed in order to establish the prevalence of Bartonella bovis and B. chomelii infections, the level of bacteremia, and the relationship between bacteremia and age or pregnancy status. The putative impact of Bartonella infection on production performance (individual milk cell count, milk yield) and reproductive status (success of artificial insemination [AI], placental retention, embryonic death, and abortion) was also assessed. The overall mean prevalence of B. bovis bacteremia was 59%, with the highest prevalence in heifers (92.5%). No B. chomelii was isolated, and 95% (114/120) of the B. bovis strains isolated and tested by PCR-restriction fragment length polymorphism belonged to type I. The level of bacteremia was higher in pregnant cows than in nonpregnant cows (P = 0.05), and the level of bacteremia rose during the last two-thirds of gestation (P < 0.001). There was no correlation between bacteremia and milk yield, individual milk cell count, success of first AI, interval between two calvings, or incidence of abortion and embryonic death. The interval from calving to first AI was shorter and the incidence of placental retention was lower in bacteremic animals than in nonbacteremic ones (P = 0.03 and P = 0.01, respectively).     

Accounting for velocity of the pivot shift test manoeuvre decreases kinematic variability

The pivot shift test is the only clinical test which correlates with knee function following rupture of the ACL. A grade is given to the pivot shift in a subjective manner, leading to efforts to quantify the bone movements and correlate them to the grade. However, the dynamic and unconstrained nature of the manoeuvre introduces important kinematic variability.Our main objective was to develop a method to lessen the variability attributable to clinician technique, therefore increasing inter-grade differences.Three different orthopaedic surgeons each performed the pivot shift test on 12 subjects. Knee joint kinematics were recorded using electromagnetic motion capture devices. Inter-clinician variability was quantified and a method was developed to diminish it, using the angular velocity of flexion. This method was then applied to a larger population composed of 127 knees with various degrees of instability, evaluated by one of eight different orthopaedic surgeons.The clinical grades given by the clinicians were in almost perfect agreement (kappa = 0.83). Normalization of kinematic parameters using the angular velocity of knee joint flexion produced by the clinicians reduced the intra-clinician variability by 20%, resulting in an intra-class correlation coefficient (ICC) of 0.52, up from 0.41 before normalization. This allowed for more significant differences between the grades of pivot shift.Simple normalisation of pivot shift kinematics using the angular velocity of flexion reduces clinician-related variability and allows for significant differences between the different grades. These results are an important step towards developing an objective measurement tool for the pivot shift phenomenon.     

老年阻塞性睡眠呼吸暂停综合征与心血管疾病的研究进展

0 引言 睡眠呼吸暂停综合征(sleep apnea syndrome, SAS)是指每晚7 h睡眠中出现持续10 s以上的呼吸暂停大于30次或睡眠呼吸暂停/低通气指数(AHI,即平均每小时呼吸暂停次数 低通气次数)≥5,60岁以上老年人AHI≥10.SAS分为三型,即阻塞性(obstructive sleep apnea, OSA)、中枢性(central sleep apnea, CSA)和混合性(mixed sleep apnea, MSA).