Is sluice gate management beneficial for spawning migrations? The case of the shark catfish (Helicophagus waandersii) in the Mun River below the Pak Mun Dam,Thailand

The reproductive ecology of shark catfish Helicophagus waandersii in the Mun River, the largest Mekong tributary in Thailand, was studied from July 2003 to December 2004. The aim of the study was to determine whether shark catfish, which contribute greatly to fish catches, benefits in terms of spawning, from the management regime of the Pak Mun Dam to open all sluice gates annually for 4 months during the rainy season. In total, 228 females were studied. The highest average gonadosomatic index (4.42% ± 1.90%) was observed in the rainy season in June 2004. Fecundity ranged from 21 550 to 191 540 eggs. Three hormonal profiles viz. testosterone (T), 17 β‐estradiol (E₂), and 17, 20 β‐dihydroxy‐4‐pregnen‐3‐one (17, 20 βP) were determined by radioimmunoassay. The highest levels of T (0.96 ng ml⁻¹), E₂ (14.37 pg ml⁻¹), and 17, 20 βP (0.81 ng ml⁻¹) were respectively measured in April to May, July, and May. Changes in the maturity stage and the annual sex hormonal profiles revealed that the spawning period of H. waandersii is from May to June. There was no spatial statistical difference (p > 0.05) for each sex steroid profiles. The results indicated that H. waandersii spawn during the rainy season in the rapid areas, both downstream and upstream, and the sluice gates opening management regime for 4 months in the rainy season is of advantage for H. waandersii in terms of feeding and nursery grounds in the upstream area. Copyright © 2006 John Wiley & Sons, Ltd.     

Analysis of disuiphide bridge function in recombinant bovine prolactin using site-specific mutagenesis and renaturation under mild alkaline conditions: a crucial role for the central disuiphide bridge in the mitogenic activity of the hormone

We have previously described a method for isolating Escherichiacoli-produced methionyl bovine prolactin (Met-bPRL) and itsrenaturation using thioredoxin. This report describes an alternativerenaturation procedure in which extracted Met-bPRL is incubatedin air at pH 10 and 20°C. Within 1 h of such treatment essentiallyall of the reduced Met-bPRL was converted to the oxidized form;this was accompanied by an increase to full mitogenic activityin the Nb2 cell bioassay. It was also found that, to minimizecontamination by high mol. wt Met-bPRL derivatives, it is essentialto have a reducing agent (dithiothreitol) present during disruptionof the bacteria and to extract the protein at neutral pH. Thecontribution of each of the three disuiphide bridges in bPRLto its bioactivity was studied with Met-bPRL variants, preparedvia site-specific mutagenesis, in which cysteines were replacedby serines to prevent disulphide bond formation. Variants lackingthe C4–C11 bridge, the C191–C199 bridge or boththese terminal bridges were as mitogenic as authentic bPRL.(Variants lacking the C191–C199 bridge had markedly increasedsolubility in the presence of deoxycholate.) In contrast, variantslacking the C58–C174 bridge had greatly reduced bioactivity,indicating that integrity of the large disulphide loop is crucialto the hormone's mitogenic activity.     

牛血清白蛋白荧光猝灭测定药物中的头孢孟多酯

应用牛血清白蛋白（BSA）荧光猝灭法建立了一种测定药物中头孢孟多酯（CEF）含量的新方法。牛血清白蛋白具有很强的内源荧光性,而头孢孟多酯溶液本身不产生荧光。当头孢孟多酯与BSA结合后,会导致其荧光强度下降。牛血清蛋白在λex=340 nm处的荧光猝灭程度与头孢孟多酯的量在一定浓度范围内呈良好的线性关系,据此建立测定药品中头孢孟多酯含量的新方法。该结合物的最大发射波长为λmax=340 nm,与头孢孟多酯物质的量浓度在2.18×10^-6~2.62×10^-5 mol·L-1范围内线性关系良好。其线性回归方程为ΔF=2.42×10^7CCEF-35.155,相关系数r=0.996 9,检出限为8.582 58×10-7 mol·L-1,RSD为0.16%,加标回收率为94.67%~98.43%。本方法操作简便、快速,用于实际样本的测定,结果满意。     

Multilineage Potential Research of Bovine Amniotic Fluid Mesenchymal Stem Cells

The use of amnion and amniotic fluid (AF) are abundant sources of mesenchymal stem cells (MSCs) that can be harvested at low cost and do not pose ethical conflicts. In human and veterinary research, stem cells derived from these tissues are promising candidates for disease treatment, specifically for their plasticity, their reduced immunogenicity, and high anti-inflammatory potential. This work aimed to obtain and characterize bovine amniotic fluid mesenchymal stem cells (AFMSC). The bovine AF from the amniotic cavity of pregnant gilts in the early stages of gestation (3- and 4-m-old bovine embryos) was collected. AFMSCs exhibit a fibroblastic-like morphology only starting from the fourth passage, being heterogeneous during the primary culture. Immunofluorescence results showed that AFMSCs were positive for β-integrin, CD44, CD73 and CD166, but negative for CD34, CD45. Meanwhile, AFMSCs expressed ES cell markers, such as Oct4, and when appropriately induced, are capable of differentiating into ectodermal and mesodermal lineages. This study reinforces the emerging importance of these cells as ideal tools in veterinary medicine; future studies aimed at a deeper evaluation of their immunological properties will allow a better understanding of their role in cellular therapy.     

牛血清白蛋白荧光猝灭法测定药物中的头孢硫脒

应用牛血清白蛋白(BSA)荧光猝灭法建立一种测定药物中头孢硫脒(C-18)物质量浓度的新方法.BSA具有很强的内源荧光性,而C-18溶液本身不产生荧光.当C-18与BSA结合后,会导致其荧光强度下降.BSA在λex=340 nm处结合C-18后的荧光猝灭强度与C-18的量在一定范围内呈良好的线性关系,据此建立测定药品中C-18含量的新方法.该结合物的最大发射波长为λmax=340 nm,与C-18摩尔浓度在2.5×10-6～3×10-5mol/L范围内线性关系良好.其线性回归方程为△F=2.177 95× 107CC-18-28.007,相关系数r=0.9962,检出限为1.60×10-6mol/L,RSD为0.24％～0.30％,加标回收率为94.36％～97.52％.该方法操作简便、快速,可用于实际样本的测定,结果满足要求.     

Stability Analysis of Information Spreading on SNS Based on Refined SEIR Model

Investigating the stability of information spreading over SNS helps to understand the principles inherent in the spreading behavior. This paper explores the mechanisms of information spreading including stifling mechanism, latent mechanism and forgetting mechanism, establishes a refined SEIR model, and builds the corresponding mean-field equations. The methods of the differential dynamics and the next generation matrix are used to calculate the equilibriums and the basic reproductive number, and the asymptotical stability of the network equilibriums are proved theoretically. Simulation experiments are carried out to analyze the effect of the spreading mechanisms on the information spreading process and the results support our conclusions.     

动态力校准中力传感器端部等效质量测量方法研究

力传感器端部等效质量是动态力校准中的重要部分,其测量误差会对动态力校准产生较大影响。本文通过了解力传感器结构,确定力传感器端部等效质量的构成,并简单介绍了四种测量端部等效质量的方法。最后,利用两次配重消去法进行实验,将不同配合不同工况下得到的结果进行对比分析,说明该方法可以较好的解决测量端部等效质量问题。     

Cationic Bovine Serum Albumin Based Self‐Assembled Nanoparticles as siRNA Delivery Vector for Treating Lung Metastatic Cancer

It is generally believed that intravenous application of cationic vectors is limited by the binding of abundant negatively charged serum components, which may cause rapid clearance of the therapeutic agent from the blood stream. However, previous studies show that systemic delivery of cationic gene vectors mediates specific and efficient transfection within the lung, mainly as a result of interaction of the vectors with serum proteins. Based on these findings, a novel and charge‐density‐controllable siRNA delivery system is developed to treat lung metastatic cancer by using cationic bovine serum albumin (CBSA) as the gene vector. By surface modification of BSA, CBSA with different isoelectric points (pI) is synthesized and the optimal cationization degree of CBSA is determined by considering the siRNA binding and delivery ability, as well as toxicity. The CBSA can form stable nanosized particles with siRNA and protect siRNA from degradation. CBSA also shows excellent abiliies to intracellularly deliver siRNA and mediate significant accumulation in the lung. When Bcl2‐specific siRNA is introduced to this system, CBSA/siRNA nanoparticles exhibit an efficient gene‐silencing effect that induces notable cancer cell apoptosis and subsequently inhibits the tumor growth in a B16 lung metastasis model. These results indicate that CBSA‐based self‐assembled nanoparticles can be a promising strategy for a siRNA delivery system for lung targeting and metastatic cancer therapy.     

A spatiotemporal model of interactions among metastable pits and the transition to pitting corrosion

A spatiotemporal model of metastable pitting at a homogeneous metal surface under potentiostatic conditions is presented. The model accounts for local changes adjacent to metastable pits and their effect on the nucleation of subsequent events. The local changes considered include concentration, potential drop and oxide film damage. The interactions among events can lead to the formation of clusters of metastable pits and to an explosive growth in the total number of pits. Effects of metastable pit generation rate, convective mass transport (e.g., solution stirring), solution conductivity and ohmic potential drop in solution on formation of corrosion patterns at the surface are presented. The effect of the presence of a stable pit is also considered.     

Effect of intrauterine infusion of ceftiofur on uterine health and fertility in dairy cows

Objectives were to determine the effects of intrauterine (i.u.) infusion of ceftiofur hydrochloride on uterine health and fertility of dairy cows already receiving PGF_2α for estrous synchronization. Holstein cows at 44 ± 3 d in milk (DIM) were blocked by parity and diagnosis of metritis in the first 14 DIM and of other illnesses and, within each block, randomly assigned to 1 of 2 treatments: a single i.u. infusion of 125 mg of ceftiofur hydrochloride at 44 ± 3 DIM (ceftiofur, n = 396), or no i.u. infusion (control, n = 416). All cows received 25 mg of PGF_2α at 37 ± 3 and 51 ± 3 DIM as part of an estrous synchronization protocol. A subset of 547 cows was evaluated for clinical endometritis immediately before treatment, and 202 cows had an aseptic uterine sample collected before the injection of PGF_2α at 51 ± 3 DIM for bacteriology and diagnosis of subclinical endometritis (≥5% neutrophils). Pregnancy on d 38 ± 3 and 180 ± 7 after the first artificial insemination, pregnancy loss, and interval from calving to pregnancy in the first 300 DIM were evaluated. The proportions of cows diagnosed with clinical endometritis before treatment were similar between ceftiofur and control treatments. Intrauterine infusion with ceftiofur did not influence prevalence of subclinical endometritis and positive uterine culture 7 d after treatment; however, it reduced the prevalence of positive uterine culture in cows with clinical endometritis (29.0 vs. 51.4%) and reduced the overall prevalence of Arcanobacterium pyogenes (1.0 vs. 7.6%) at 51 ± 3 DIM. Cows with clinical endometritis had increased prevalence of A. pyogenes (10.3 vs. 1.5%), Escherichia coli (5.9 vs. 0.75%), and overall positive uterine culture (41.2 vs. 22.4%); however, cows with subclinical endometritis only had an increased prevalence of A. pyogenes (10.2 vs. 1.5%). Ceftiofur did not affect pregnancy per artificial insemination in all cows or in cows previously diagnosed with metritis or clinical endometritis. Interval to pregnancy was similar for control and ceftiofur cows. Intrauterine infusion of ceftiofur hydrochloride reduced the prevalence of uterine infection in cows with clinical endometritis, and the prevalence of A. pyogenes, but did not affect the prevalence of subclinical endometritis or fertility of dairy cows already receiving PGF_2α.