Changes of K+ channels of outer hair cells in guinea pig cochlea with streptomycin ototoxicity

AIM:To study the changes of K⁺ channels of outer hair cells in guinea pig cochlea with streptomycin ototoxicity. METHODS:Auditory brainstem responses (ABR) and whole-cell patch clamp techniques were used.RESULTS:(1) The body weight of guinea pigs with streptomycin ototoxicity decreased significantly; (2) The ABR threshold markedly increased in streptomycin group (Ⅱ,Ⅲ);(3)The number of dissociated outer hair cells of guinea pigs (Ⅱ,Ⅲ) was lower than that of control (Ⅰ); (4) Streptomycin decreased the Ca²⁺-sensitive K⁺ currents and delayed outward K⁺ currents distinctly; (5) There was no significant difference of K⁺ currents between Ⅰ and Ⅱ/Ⅲ. CONCLUSION:These results suggest that the inhibition of K⁺ channels is the basis of streptomycin ototoxicity, but not the direct reason for cell death.     

Role of calcineurin in airway remodeling in guinea pig model of asthma

AIM:To investigate the role of calcineurin (CaN) in airway remodeling in guinea pig model of asthma.METHODS:Male guinea pigs were randomly divided into three groups: control, asthma group and CsA group. The following parameters were measured: 1. The protein content, cell count and differential count of BALF; 2. The amount of [³H]-TdR incorporation into central airway smooth muscle; 3. The mean thickness of airway wall and airway smooth muscle of small airwaysl; 4.CaN activity of trachea and lung tissue.RESULTS:1. The protein content, cell count and eosinophil of BALF in CsA group were 46%, 51% and 60% lower than those in asthma group, respectively (P＜0.01); 2. [³H]-TdR incorporation in CsA group was 22% lower than that in asthma group (P＜0.05);3. The mean thickness of airway wall and airway smooth muscle were 34% and 37% less in CsA group than those in asthma group, respectively (P＜0.01); 4. CaN activity of lung tissue and trachea were 52% and 44% lower in CsA group than those in asthma group, respectively (P＜0.01).CONCLUSION:CsA reduced airway remodeling in guinea pig model of asthma, indicating the role of CaN in the airway remodeling.     

Changes of intracellular potassium activity and membrane potential in guinea pig ventricular myocardium during superfusion with low sodium solutions and effects of low pH

AIM:To investigate the changes in intracellular potassium activity(aⁱK) and membrane potential(V_m) induced by low external sodium infusion (Low [Na]_o) and to detect the mechanisms involved and the relationship between aⁱK and V_m. METHODS:aⁱK and V_m were measured in infusion with different sodium concentrations using methods of convenient and ion selective microelectrodes in guinea pig ventricular myocardium. RESULTS:Low [Na]_o resulted in a decrease in aⁱK and an increase in V_m in a Na⁺ concentration-dependent manner.At the same time,contraction and resting potential increased, and action potential duration decreased markedly,but action potential amplitude was not affected. A change of the pH from 7.4 to 7.0 in low [Na]_o solution reduced the decrease in aⁱK, but did not affect the increase in V_m.CONCLUSION:A better linear relationship appeared between the changes in aⁱk and [Na]_o or in V_m and [Na]_o,while during each low [Na]_o the change in both aⁱK or V_m may reach a new balance level.     

Upregulation of neurokinin A levels by nerve growth factor in the experimental asthmatic guinea pig

AIM: To explore the regulatory mechanism of nerve growth factor (NGF) on neurokinin A in the experimental asthmatic guinea pig. METHODS: Radioimmunoassay was used to determine the alteration of neurokinin A levels in the lower respiratory tract and visceral sensory afferent sites while NGF was absent (inhalation of NGF antibody through nasal cavity) in the asthmatic guinea pig. RESULTS: The contents of neurokinin A in the trachea, bronchus, lung, C₇-T₅ spinal ganglia and the correspondent spinal dorsal horn, nodose ganglia and solitary nucleus area in the experimental asthmatic guinea pig with the absent of NGF in the respiratory tract were much lower than those in the asthmatic and control groups (P＜0.01). CONCLUSION: NGF upregulated the contents of neurokinin A in the lower respiratory tract and visceral sensory sites of the experimental asthmatic guinea pig, and both might be involved in the pathogenesis of asthma.     

Nutritive constituents of Silky fowl eggs: comparison with hen eggs of White Leghorn origin

In the present study, proportional parts, amounts of major constituents, vitamins, minerals and fatty acids composition of Silky fowl eggs were examined compared with those of hen eggs. The ratio of egg yolk weight to whole egg weight of Silky fowl egg was significantly larger than that of egg yolk of hen egg. The amount of cholesterol of Silky fowl eggs were significantly (P < 0.01) less than those of hen eggs. The amount of vitamins (B2, B6, D and E), calcium and potassium in Silky fowl eggs were significantly higher than those of hen eggs. Unsaturated fatty acids in Silky fowl eggs were 62.5% among total fatty acids, the unsaturated fatty acids of hen eggs were 53.9%. Especially, the contents of arachidonic acid, docosapentaenoic acid and docosahexaenoic acid in Silky fowl eggs were significantly larger than in hen eggs.     

Salmonella Gallinarum field isolates and its relationship to vaccine strain SG9R

1. The aim of the present study was to determine if the 9R-strain of the Salmonella Gallinarum live vaccine was responsible for having fowl typhoid outbreaks in chicken flocks from both chicken and turkey breeders as well as to verify the antimicrobial resistance of the isolates from the outbreaks.

2. The triplex polymerase chain reaction, standard antimicrobial test, beta-lactamase genes identification and Ion Torrent PMG whole-genome sequence were used in the field isolates and in the vaccine strain of S. Gallinarum.

3. The 60 tested isolates were not from vaccine origin and manifested high resistance to drugs from macrolide and quinolone groups. Whole-genome sequencing (WGS) and single nucleotide polymorphism analysis on selected isolates for core genes from Salmonella enterica confirmed the wild origin of these isolates and showed two possible sources of S. Gallinarum in the studied outbreaks.

4. S. Gallinarum isolated from fowl typhoid outbreaks in the studied period were not caused by the use of the SG9R live vaccine. The source of strains sequenced was diverse.     

禽腺病毒血清4型贵州株全基因序列分析

为了解禽腺病毒血清4型(FAdV-4)地方流行毒株的分子进化情况,基于实验室分离的2株FAdV-4贵州株GZ-BJ株和GZ-QL株,分别对2株FAdV-4毒株进行PCR分段扩增,扩增产物克隆至载体,提取质粒进行PCR和双酶切鉴定后筛选出重组质粒进行测序,将测序结果依次拼接得到病毒的全基因组,获得FAdV-4贵州株的全基因序列,并对其进行序列和遗传进化分析。结果显示,通过PCR分段扩增成功获得了2株FAdV-4贵州株(GZ-BJ株和GZ-QL株)的全基因序列,长度分别为43352、43723 bp,FAdV-4 GZ-BJ株全基因序列长度比FAdV-4 GZ-QL株短371 bp,少6个ORF(22K、putative 9.1 ku、u-exon、ORF17、ORF28、ORF42),二者的氨基酸同源性为57.1%。2株FAdV-4贵州株同国内外不同地区FAdV-4毒株核苷酸同源性在88.7%~100%,与FAdV-4经典毒株ON1比对,2株FAdV-4贵州株和国内FAdV-4分离株均缺失ORF19、ORF27、ORF30。系统进化树分析显示,2株FAdV-4贵州株GZ-BJ株和GZ-QL株仍属于Ⅰ群C种FAdV。研究结果表明,2株贵州株FAdV-4 GZ-BJ株和FAdV-4 GZ-QL株较国内外FAdV-4毒株均存在进化与突变,且FAdV-4 GZ-BJ株变化较大,但尚未改变其血清型,这为探索FAdV-4致病机理的分子机制研究提供依据。     

鸡白痢鸡伤寒对种鸡生产性能的影响

鸡白痢鸡伤寒是一种经蛋垂直传播且具有严重危害性的传染病。为在种鸡群中进行血清学检查,检出并淘汰阳性鸡以确保无白痢的健康种鸡群,达到种群净化的目的,本研究应用全血平板凝集试验对江苏太仓广东温氏家禽有限公司某种鸡场的5133羽新兴黄鸡进行了检测。检测结果:鸡白痢鸡伤寒的抗体阳性检出率为2.7%。在相同的饲养环境下通过为时40 d试验,对阳性鸡群与阴性鸡群的产蛋率,受精率及孵化率进行比较观察,结果表明:鸡白痢鸡伤寒抗体呈阳性鸡群的上述生产性能在不同程度上低于抗体呈阴性鸡群。鸡白痢疾鸡伤寒阳性带菌鸡群的产蛋率、受精率、孵化率分别低于鸡白痢阴性鸡群为8.1%～21.8%、0.87%～1.6%、10.6%～11.4%。