Determination of beta-lactams in milk using a surface plasmon resonance-based biosensor

Two surface plasmon resonance (SPR)-based biosensor assays for detection of beta-lactam antibiotics in milk are reported. The assays are based on the enzymatic activity of a carboxypeptidase converting a 3-peptide into a 2-peptide, a reaction that is inhibited in the presence of beta-lactams. Antibodies were used to measure either the amount of formed enzymatic product or the amount of remaining enzymatic substrate. Both assays detected different beta-lactams at or below European maximum residue limits (MRLs), and the detection limit for penicillin G was 1.2 microg/kg and 1.5 microg/kg for the 2- and 3-peptide assays, respectively. The precision (CV) was < 5%, both within and between assays at the penicillin G MRL (4 microg/kg). The biosensor results obtained upon analysis of incurred milk samples were compared with results obtained by liquid chromatography (HPLC), and the method agreements were, in general, good.     

Expression and properties of two types of protein kinase C: alternative splicing from a single gene

Two complementary DNA's, encoding the complete sequences of 671 and 673 amino acids for subspecies of rat brain protein kinase C, were expressed in COS 7 cells. The complementary DNA sequence analysis predicted that the two enzymes are derived from different ways of splicing and differ from each other only in the short ranges of their carboxyl-terminal regions. Both enzymes showed typical characteristics of protein kinase C that responded to Ca2+, phospholipid, and diacylglycerol. The enzymes showed practically identical physical and kinetic properties and were indistinguishable from one of the several subspecies of protein kinase C that occurs in rat brain but not in untransfected COS 7 cells. Partial analysis of the genomic structure confirmed that these two subspecies of protein kinase C resulted indeed from alternative splicing of a single gene.     

Persistent BVDV infection in mousedeer infects calves. Do we know the reservoirs for BVDV?

Bovine virus diarrhoea virus (BVDV)-1f was isolated from a Lesser Malayan Mousedeer in Copenhagen Zoo during a routine screening. Analysis of animals related to the Copenhagen mousedeer revealed that its mother and all siblings were virus positive, a pattern also seen for persistently infected (PI) cattle. BVDV could be transmitted from the PI mousedeer to a calf after indirect contact. The host spectrum for BVDV seems to be even wider than expected; the implications for BVDV control are discussed.     

Successful conversion of equine atrial fibrillation using oral flecainide

Atrial fibrillation is the most common arrhythmia affecting performance in horses. Conversion to sinus rhythm carries a good prognosis if no significant underlying cardiac disease is present and horses commonly return to performance at the previous level or above. The drug most commonly used to convert equine atrial fibrillation is quinidine. However, quinidine has the potential for a number of adverse effects including colic, nasal mucosal edema, dyspnea and laminitis. Quinidine also requires administration through a nasogastric tube, as the drug is very bitter and acidic and may cause oral ulcerations if administered PO. Flecainide is an antiarrhythmic agent of Singh-Vaughan Williams class Ic, whereas quinidine belongs to class Ia. Intravenously administered flecainide has been reported to be a safe and effective drug for treatment of induced atrial fibrillation in the horse, with fewer adverse effects compared to quinidine, but has been less effective when administered to horses with naturally occurring atrial fibrillation. The pharmacokinetics of oral flecainide and the oral dosage required to treat equine atrial fibrillation have been determined. To the authors' knowledge, there are no reports describing treatment of equine atrial fibrillation with oral flecainide. This report describes the successful conversion of naturally occurring atrial fibrillation, by means of oral flecainide, in a horse.     

Affinity and rate constants for interactions of bovine folate-binding protein and folate derivatives determined by optical biosensor technology. Effect of stereoselectivity

The interactions between bovine folate-binding protein (FBP) and different folate derivatives in pure diastereoisomeric forms were studied at pH 7.4 by a surface plasmon resonance technology (Biacore). The results show that folic acid had the most rapid association rate (k(a) = 1.0 x 10(6) M(-)(1) s(-)(1)), whereas (6S)-5-HCO-5,6,7,8-tetrahydrofolic acid had the most rapid dissociation rate (k(d) = 3.2 x l0(-)(3) s(-)(1)). The equilibrium dissociation constant (K(D)), calculated from the quotient of k(d)/k(a), showed that the two forms of folates not occurring in nature, that is, folic acid and (6R)-5-CH(3)-5,6,7,8-tetrahydrofolic acid, had the highest affinities for FBP, 20 and 160 pmol/L, respectively. The results thus show that there were great differences in the interactions between folate-binding protein and the major forms of folate derivatives. The nutritional implications of these differences are discussed.     

Early pathogenesis of classical swine fever virus (CSFV) strains in Danish pigs

Host-virus interactions play an important role for the clinical outcome of classical swine fever virus (CSFV) infections in pigs. Strain virulence, host characteristics and environment are all factors that markedly influence disease severity. We tested CSFV strains of varying virulence in an experimental set-up, reducing the influence of host and environmental factors. Thus, weaner pigs were inoculated with one of 4 CSFV strains in order to compare the pathogenesis for a 3-week-period after infection. CSFV strains selected were 2 new and 2 previously characterized. None of these strains had been tested in Danish outbred pigs before. Clinical observations grouped the infected pigs into two different categories reflecting either non-specific, mainly gastro-intestinal, problems, or severe disease including high fever within the first week after inoculation. Gross-pathological findings varied between strains, however, lymphoid atrophy and growth retardation represented a consistent finding for all 4 strains. Virus distribution, viral load and in particular virus persistence differed, but supported present practice that recommends lymphoid tissue, most optimal tonsil and lymph nodes, as target material to be applied for early laboratory diagnosis. The present study demonstrated constraints associated with early detection of infections with CSFV strains of low virulence. Since neither clinical symptoms nor pathological lesions observed with these strains constituted characteristic signs of CSF, the risk of neglecting a CSF suspicion is immediate. Therefore, topical information on new outbreaks and continuous enhancement of an efficient surveillance system is of great importance to prevent further spread of CSF within the pig population.     

Prognostic value of clinicopathologic variables obtained at admission and effect of antiendotoxin plasma on survival in septic and critically ill foals

This prospective study compared survival rates of critically ill and septic foals receiving 1 of 2 different types of commercial equine plasma and analyzed admission variables as possible predictors of survival. Standardized clinical, hematologic, biochemical, and hemostatic admission data were collected and foals received either conventional commercially available hyperimmune equine plasma or equine plasma specifically rich in antiendotoxin antibodies in a double-blinded, coded fashion. Sepsis was defined as true bacteremia or sepsis score >11. Overall survival rate to discharge was 72% (49/68). Foals that were nonbacteremic and demonstrated a sepsis score of < or = 11 at admission had a 95% (18/19) survival rate. The survival rate to discharge for septic foals was 28/49 (57%), with truly bacteremic foals having a survival rate of 58% (14/24), whereas that for nonbacteremic, septic foals was 56% (14/25). Sensitivity and specificity for sepsis score >11 as a predictor of bacteremia were 74 and 52%, respectively. For the entire study population, a higher survival rate to discharge was documented for those foals receiving hyperimmune plasma rich in antiendotoxin antibodies (P = .012, odds ratio [OR] 6.763, 95% confidence interval [CI]: 1.311, 34.903). Administration of plasma rich in antiendotoxin antibodies also was associated with greater survival in septic foals (P = .019, OR 6.267, 95% CI: 1.186, 33.109). Statistical analyses demonstrated that, among 53 clinical and clinicopathologic admission variables, high sepsis score (P < .001), low measured IgG concentration (P = .01), high fibrinogen concentration (P = .018), low segmented neutrophil count (P = .028), and low total red blood cell numbers (P = .048) were the most significant predictors of overall mortality.     

鱼目标三维信息采集平台中干扰现象的判定与消除

为了保证鱼类行为数据采集的准确性和鲁棒性,本实验提出了一种干扰消除算法,对鱼目标三维定位算法进行优化。主要针对鱼目标三维信息采集平台中出现的一种由全反射引起的干扰现象,利用光学原理分析其出现原因,总结干扰现象特点,之后通过基于轮廓的运动目标跟踪方法,设计干扰消除算法,优化鱼目标三维定位算法,实现对干扰现象影响的消除,提高定位精度。通过对红鲫和仿真鱼的定位实验,结果发现,本实验提出的去干扰优化算法可以有效消除干扰像对于目标定位的影响,准确获取鱼目标的三维坐标,保证鱼目标三维定位跟踪的准确性和鲁棒性,提高鱼目标行为信息采集精度。     

Determination of the sequence of the complete open reading frame and the 5'NTR of the Paderborn isolate of classical swine fever virus

The classical swine fever (CSF) epidemic in the Netherlands in 1997-1998 lasted 14 months, during which 429 infected and 1300 at risk herds were culled, at an estimated economical cost of 2 billion US dollars. Despite the overwhelming scale of the epizootic, the CSF virus (CSFV) strain causing the outbreak has remained largely uncharacterized. The Dutch epizootic is epidemiologically linked to a small CSF outbreak in 1997, in Paderborn in Germany. E2 and partial 5' NTR sequencing has shown that the index Paderborn isolate, and several Dutch isolates taken during the 1997-1998 epizootic, are virtually identical, confirming that the Paderborn isolate triggered the Dutch outbreak, and furthermore showing that this single isolate was stable throughout the whole Dutch outbreak (the above reviewed in [C. Terpstra, A. J. de Smit, Veterinary Microbiol. 77 (2000) 3-15]). We determined the nucleotide sequence of the 5' NTR (by 5' RACE) and the complete open reading frame of the Paderborn isolate (GenBank AY072924). Our sequence was identical to previously published partial 5'NTR and E2 sequences for the index Paderborn 1997 and Dutch 1997 (Venhorst) isolates, confirming the identity of the virus we sequenced. Phylogenetic analysis based on the complete open reading frame showed that Paderborn is genetically very different from common European laboratory reference strains. Neutralization studies showed that Paderborn is also antigenically very different from common laboratory strains such as Alfort 187. Paderborn is the only recent European CSFV field isolate for which a complete sequence is available, and given Paderborns genetic and antigenic uniqueness, the Paderborn sequence may have practical use for diagnostic and vaccine antigen development.