Identification of novel immunoreactive proteins of Streptococcus zooepidemicus with potential as vaccine components

Background

Streptococcus zooepidemicus is an important opportunistic pathogen of the equine respiratory and reproductive tracts. A normal tonsillar and mucosal commensal, it becomes invasive under conditions of stress such as virus infection, weaning, high temperature, prolonged transportation and failure of uterine involution. The aim of this study was to evaluate the vaccine potential of several surface exposed and secreted proteins of a novel mucoid clone of SzNC78 (ST-307) from an epizootic of equine respiratory disease.

Methods

An expression gene library of SzNC78 was probed with a pool of convalescent equine sera from a clonal epizootic of respiratory disease. Eleven proteins were selected and purified based on putative function, surface expression or secretion and possible importance as virulence factors. Three additional proteins (AhpC, GAPDH and enolase) were also included based on their putative virulence function. Groups of ICR mice were vaccinated subcutaneously with each recombinant antigen and QuilA and later challenged with SzNC78.

Results

SzM protected 100% mice (P < 0.01), followed by SzP and HylC which protected 90% mice (P = 0.01). MAP, SzMAC and ScpC each protected 63% (P < 0.05) mice. No control mouse survived challenge. SzM, MAP and ScpC in combination protected mice against a 10 fold higher dosage of SzNC78 than each antigen given separately. Protection against heterologous challenge (SzW60) was conferred by combinations of HylC + ScpC (60%; P = 0.05), followed by HylC + MAP (50%; P = 0.06) and ScpC + MAP (40%; P = 0.1). Serum antibody responses of horses recently recovered from Sz respiratory infection were highest against ScpC, MAP and SzP. A combination of SKC and Sz115 stimulated no protection against challenge with SzW60.

Conclusion

A subset of Sz proteins reactive with convalescent equine antibody have potential as components of experimental vaccines to aid in prevention of opportunistic Sz infections.     

Diagnostic markers in combination improve the identification of growth-restricted neonates

Background

The identification of growth-restricted neonates is hampered by the lack of an appropriate diagnostic tool.

Aim

To determine the value of combining diagnostic markers in detecting growth-restricted neonates.

Methods

A set of anthropometric indices, nutritional status and placental weight were assessed in the study population soon after birth. Insulin-like growth factor I (IGF-I) and its binding protein 3 (IGFBP-3) were assayed in cord blood. Babies having low values (≤25th centile for gestational age) in 0, 1 or more of four anthropometric indices were classified as Group₂₅0, Group₂₅1 and Group₂₅2, respectively. For statistical evaluation the Mann-Whitney test and a multiple regression analysis were performed.

Results

One hundred-eighty (180) singleton babies of over 36 weeks of gestational age (GA) were studied. IGF-I, IGFBP-3 levels and placental weight were significantly lower in Group₂₅2 than both Group₂₅0 (P < 0.0001) and Group₂₅1 (p < 0.0001 to p = 0.03). Group₂₅1 and Group₂₅0 did not differ significantly regarding IGF-I and IGFBP-3 levels (p values 0.09 and 0.13, respectively). The combination of anthropometric indices enhanced their ability to predict IGF-I, IGFBP-3 levels and placental weight; the nutritional status of the babies added power to all individual models in predicting the three outcome variables. Analogous results were obtained when the 10th (instead of the 25th) centile for GA was used for the anthropometric indices.

Conclusion

The combination of simple diagnostic markers of growth restriction can define a reference test with enhanced diagnostic potential compared to the potential of the same markers in isolated use.     

Diabetes attenuates the minimum anaesthetic concentration (MAC) and MAC-blocking adrenergic response reducing actions of clonidine in rats

BACKGROUND: It is well known that clonidine, an alpha2 agonist, reduces anaesthetic requirement and attenuates haemodynamic responses against noxious stimuli. However, the diabetic state is known to affect several functions of alpha2 adrenoceptors. We investigated the effects of streptozotocin (STZ)-induced diabetes mellitus (DM) on these beneficial actions of clonidine in halothane-anaesthetized rats. METHODS: The rats were randomly assigned to one of three groups: diabetes (n=24, induced by 50 mg x kg(-1) IV STZ), diabetes treated with insulin (n=24), or control (n=24). We evaluated the effects of clonidine on minimum anaesthetic concentration (MAC) and minimum concentration of halothane needed to suppress cardiovascular responses evoked by a noxious stimulus (MAC-blocking adrenergic responses: MAC-BAR) in each group. MAC and MAC-BAR of halothane were determined by the tail clamp method. MAC-BAR was defined as the MAC which attenuated haemodynamic responses within 10% following the tail clamp. RESULTS: The diabetic state decreased MAC of halothane by approximately 10%, while MAC-BAR of halothane had been little affected. In the diabetes group, MAC reducing action of clonidine (30 and 100 microg x kg(-1), IV) was completely abolished and MAC-BAR reducing action of clonidine was partially reduced (30 but not 100 microg x kg(-1), IV). Insulin treatment preserved these actions of clonidine. CONCLUSION: It is suggested that the diabetic state attenuates the beneficial actions of clonidine and that insulin treatment of diabetes preserves these actions of clonidine.     

车间空气中尿素卫生标准的研究

[目的 ]研究车间空气中尿素的国家卫生标准。 [方法 ]现场接触工人的职业流行病学调查。尿素的急性及慢性毒性试验。收集国内外有关资料。 [结果 ]尿素的大鼠经口LD50 为 8471mg/kg。大鼠吸入慢性阈浓度为 (45 9± 9 8)mg/m3。车间空气中尿素浓度在 10mg/m3,未发现接触工人有中毒症状。 [结论 ]建议车间空气中尿素的最高容许浓度为10mg/m3,其时间加权平均容许浓度为 5mg/m3。     

IEEE 802.11 WLAN多业务综合传输性能分析

研究了IEEE802．11标准中的多址接入协议(MAC)在数据、语音业务综合传输情况下的性能。数据业务由分布协调功能(DCF)传送,语音业务由点协调功能(PCF)传送。通过仿真,评估了协议参数对网络通过量和平均MAC协议数据单元(MPDU)时延的影响。确定在一定数据通过量前提下IEEE802．11能支持的最大语音用户个数。特别地,语音业务对时延抖动敏感,指出了影响其抖动性能的主要因素。数值结果表明,合理选择参数对性能至关重要,IEEE802．11性能必须在语音站点数量和数据业务通过量之间进行折衷。最后。通过理论推导验证了仿真结果的正确性。     

木尘对健康危害及卫生标准研究

长期接触木尘可使鼻粘膜炎、慢性支气管炎检出率明显增高。木工的鼻粘膜炎检出率与车间内木尘浓度有关。将木尘浓度控制在5mg/m~3以下,鼻粘膜炎检出率接近对照组水平,但不易实现。如木尘浓度维持在10mg/m~3或10mg/m~3以上时,木工的鼻粘膜炎检出率明显增高,比对照组高19.84～21.0%,对肺功能损害也比较重。若将木尘浓度控制在5～10mg/m~3之间,鼻粘膜炎检出率比对照组高13.7～14.3%,对工人健康虽有一定的危害但不严重。结合我国经济条件和防尘技术的可行性,建议木尘最高容许浓度为8mg/m~3。