A Nonluminescent and Highly Virulent Vibrio harveyi Strain Is Associated with “Bacterial White Tail Disease” of Litopenaeus vannamei Shrimp

Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was characterized by “white tail” and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905) was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN), white tail disease (WTD) or penaeid white tail disease (PWTD). To differentiate from such diseases as with a sign of “white tail” but of non-bacterial origin, the present disease was named as “bacterial white tail disease (BWTD)”. Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system

Evolutionary Trajectory of White Spot Syndrome Virus (WSSV) Genome Shrinkage during Spread in Asia

Background - White spot syndrome virus (WSSV) is the sole member of the novel Nimaviridae family, and the source of major economic problems in shrimp aquaculture. WSSV appears to have rapidly spread worldwide after the first reported outbreak in the early 1990s. Genomic deletions of various sizes occur at two loci in the WSSV genome, the ORF14/15 and ORF23/24 variable regions, and these have been used as molecular markers to study patterns of viral spread over space and time. We describe the dynamics underlying the process of WSSV genome shrinkage using empirical data and a simple mathematical model. Methodology/Principal Findings - We genotyped new WSSV isolates from five Asian countries, and analyzed this information together with published data. Genome size appears to stabilize over time, and deletion size in the ORF23/24 variable region was significantly related to the time of the first WSSV outbreak in a particular country. Parameter estimates derived from fitting a simple mathematical model of genome shrinkage to the data support a geometric progression (

Value of a single preoperative PFA-100® measurement in assessing the risk of bleeding in patients taking cyclooxygenase inhibitors and undergoing total knee replacement

Background. The usefulness of the PFA-100® in assessing the risk of bleeding in non-cardiac surgery is not clear. This study aims to examine this by correlating preoperative PFA-100® measurement with perioperative bleeding in patients receiving cyclooxygenase (COX) inhibitors. Methods. PFA-100® with adenosine-5'-diphosphate (ADPCT) and epinephrine (EPICT) cartridges were measured before operation in consecutive patients undergoing elective total knee replacement and taking different COX inhibitors. Surgery and anaesthesia were performed by the same team using standardized techniques. Intraoperative blood loss and postoperative drain output were recorded by anaesthetists and nurses blinded to the PFA-100 ® measurements. Surgeons, similarly blinded, were asked to rate the quality of haemostasis. Correlation was sought between these data and PFA-100® measurements. Results. Thirty patients were studied, involving 51 knees. Preoperative PFA-100® EPICT was correlated with drain output (r=0.30, P=0.03). The correlation becomes stronger when a 20 in vitro haemodiluted sample was used for measurement (r=0.42, P=0.01). Receiver-operating characteristic curve analysis using the diluted measurements [area under curve (AUC) 0.74 (95 CI 0.54-0.94)] suggested using a cut-off value of 188 s for EPICT, which will predict excessive drain output with 89 sensitivity, 54 specificity, and a likelihood ratio of 1.93. Diluted EPICT was also correlated with surgeon rating of haemostasis (r=0.36, P=0.04) although none of the measurements correlated with intraoperative blood loss. Conclusions. Preoperative PFA-100® prolongation is correlated with increased postoperative drain output. It can be a potentially useful preoperative measurement in patients taking COX inhibitors.link_to_OA_fulltex

Comprehensive Preoperative Evaluation of Platelet Function in Total Knee Arthroplasty Patients Taking Diclofenac

The severity and variability of platelet dysfunction in preoperative arthritic patients taking nonsteroidal anti-inflammatory drugs (NSAIDs) have not been well studied previously. We evaluate 30 preoperative patients taking diclofenac (group D) by routine coagulation screen, platelet count, fibrinogen concentration, thrombelastography, and PFA-100 (Dade Behring, Inc, Deerfield, IL)) platelet function analyzer. Ten patients (group P) and 30 healthy volunteers (group N) not taking NSAIDs serve as control. Diclofenac causes significant prolongation of mean PFA-100 closure times (P < .0001). However, the prolongation is highly variable; and up to 33% of patients are still having normal platelet function despite diclofenac consumption. Low body weight is a significant predictor of more severe platelet dysfunction (P < .01). Other tests are not useful. We conclude that not all patients taking NSAIDs have similar platelet dysfunction and that preoperative monitoring with PFA-100 is preferable. © 2008 Elsevier Inc. All rights reserved.link_to_subscribed_fulltex