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.     

Inducible nitric oxide synthase and arterial pressure regulation

AIM and METHODS:To clarify the role of inducible nitric oxide synthase (iNOS) in the regulation of blood pressure,in the present study, we examined the effect of aminoguanidine (AG), a selective inhibitor of iNOS on the hemodinamical response of Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats to low (0.3%) or high (8%) sodium chloride (NaCl) infusion by chronical in vivo hemodynamic experiment, and the effect of NaCl or NaCl plus AG infusion on urinary nitrate (NO₃)/nitrite (NO₂), the end product of nitric oxide (NO), excretion by Greiss Reaction. Furthermore, NOS activity assay was also carried out to probe the effect of NaCl and AG on calcium-dependent or independent NOS activity in renal tissue. RESULTS:1. High or low NaCl-infused DR rats and low NaCl-infused DS rats have no hemodinamical response to AG, however, the hypertensive effect of high NaCl (8%) infusion on DS rats were greatly amplified by co-infusion of AG. 2. Administration of high NaCl significantly elevated the iNOS activity of renal tissue, and greatly increased urinary NO₃/NO₂ excretion. CONCLUSION:Inducible NOS is an important modulator of arterial pressure, especially in case of higher blood pressure.     

ESP值和黏粒含量对土壤表面封闭作用的影响

降雨导致土壤表面结皮形成封闭是自然现象,它能降低土壤入渗,增加土表径流,导致土壤侵蚀。该文系统地研究了不同性质土壤表面的封闭作用过程,分别确定封闭过程中的物理机械作用和化学作用。试验采用了具有不同土壤交换性钠百分率(ESP)值(2、5、10、20)和黏粒含量(10％、20％、40％、60％)的4种土壤进行降雨模拟试验,通过土壤表面播撒磷石膏(PG)(2000 kg/hm²)和PG与聚丙烯酰胺(PAM)(PG 2000 kg/hm²+PAM 20 kg/hm²)混合物的处理,分别抑制了土壤的化学封闭和物理封闭,论述了ESP值和黏粒含量对土壤化学封闭和物理封闭作用的影响,结果表明：在高ESP值土壤中,化学封闭作用占土壤封闭的主导作用;低ESP值土壤中,土壤的物理封闭作用增大。当黏粒含量较低时,土壤物理封闭作用较低;当黏粒含量较大时,土壤物理封闭作用显著增大。     

白蚁肠道可培养菌群及其功能初探

白蚁是一种危害严重的昆虫,其以破坏木质而家喻户晓.文献表明,白蚁对木质强大的消化能力很大程度上取决于其肠道微生物的影响.为了探究白蚁肠道微生物的类群,本试验以黑翅土白蚁为材料,分离纯化获得其肠道主要可培养微生物的纯培养112种,其中喜氧菌35种,厌氧菌77种;在分离出的微生物类群中,通过刚果红法初步筛选出12种喜氧菌菌株可能具有纤维素酶活性,其最大透明圈达到4.0㎝×4.0㎝;进一步检测这些菌株的纤维素酶活性发现,12株菌均具有羧甲基纤维素钠盐(CMC-NA)酶活性和滤纸酶活性,但是大部分菌株羧甲基纤维素酶活性较弱,而一些菌株如 NBY14滤纸酶活较高,可达到16.188u/mL.试验结果可为黑翅土白蚁防治提供依据,亦可为纤维素酶的开发利用奠定基础.     

磺胺间甲氧嘧啶钠注射液含量测定的能力比对结果分析

为加强兽药检验检测机构能力建设,进一步提升检测技术水平,组织开展了全国省级兽药检验机构磺胺间甲氧嘧啶钠注射液含量测定的能力比对。依据《中国兽药典》2020年版一部附录0701电位滴定法与永停滴定法以及中国合格评定国家认可委员会（CNAS）规定的程序进行本次能力比对。分别采用单因子方差分析法和Ss≤0.3σ准则对测试样品进行均匀性检验,采用t检验方法和■准则对样品进行稳定性考察,采用Z比分数评价各参加实验室的测试结果。参加本次能力比对的36家兽药检测实验室中,33家结果为满意,满意率91.7%。     

基于Bacillus cereus 3BS1的生物肥研究

[目的]本研究主要目的是探索海藻酸钠细菌颗粒生物肥最佳基材配方,对此种生物肥在贮存及应用中的性质及土壤中降解特性进行研究。[方法]生物肥最佳包埋基材的筛选,细菌计数法研究生物肥在4℃和室温条件下贮存时细菌活性的变化情况,通过生物肥直径变化研究其在土壤中的生物降解情况。[结果]研究表明,基材配方为1.5%海藻酸钠+0.5%大米粉的生物肥,能够达到最佳构形及最高细菌活性,与未加入大米粉的1.5%纯海藻酸盐基材相比,细菌包含率最高,为112.3%,且在贮存过程中能够保持细菌的高活性。此生物肥埋在土壤中3 cm深时降解最快,11 d可完全降解。[结论]获得一种低成本、实用、高效的生物肥,基材最佳配方为1.5%海藻酸钠+0.5%大米粉。     

Analysis on Sustained Release of Protein from Microcapsule Prepared by Alginate

The paper studies a drug deliversy system for protein and find the optimum preparation condition.Cross-linked alginate(Alg) microcapsule was used to prepare microcapsule for protein,using bovine serum album(BSA) as a model drug.Effect of different cations and content of protein on configuration,size and enveloped rate of microcapsule were investigated.It is shown that Ba-Alg microcapsule has steady configuration,homogeneous size and high-enveloped rate.Also electrophoresis of native BSA before microencapsulation and after microencapsulation is measured by(SDS-PAGE),it is found that no significant change is observed BSA integrity.Release of BSA from microcapsule in vitro presents sustained release in some extent,and initial burst effect is significantly obvious.Microenpsulation drug in alginate will be a wishful drug delivery system.     

不同浓度褪黑素对氯化钠胁迫下宝岛蕉幼苗的影响

为了研究不同浓度褪黑素对于宝岛蕉幼苗氯化钠胁迫的影响,通过不同浓度褪黑素处理宝岛蕉幼苗叶片,研究其对宝岛蕉幼苗叶片和根系的可溶性糖含量、MDA含量、脯氨酸含量及叶质膜透性的影响。结果表明,100μmol/L褪黑素能够降低宝岛蕉幼苗叶质膜透性,提高叶片和根系可溶性糖含量,降低叶片和根系MDA含量,提高叶片和根系脯氨酸含量,提高幼苗的耐盐性,以缓解氯化钠胁迫对宝岛蕉幼苗的伤害。     

盛荚期喷施亚硒酸钠对大豆籽粒硒含量及单株产量的影响

为了研究喷施亚硒酸钠对大豆籽粒硒含量及单株产量的影响,采用裂区设计,主区为盛荚期喷施不同用量的亚硒酸钠,共5个处理（CK（清水）：0 g/hm²,C1:30 g/hm²,C2: 60 g/hm²,C3: 90 g/hm²,C4: 120 g/hm²）,副区为8个大豆品种。分析8个大豆品种在喷施5种用量亚硒酸钠处理中籽粒硒含量及单株产量变化规律。结果表明,试验地土壤达到富硒水平,在CK处理中,不同大豆品种籽粒硒含量均未达到富硒大豆标准,需要额外喷施硒肥。随着喷施亚硒酸钠用量的增加,8个大豆品种籽粒中硒含量均呈增加趋势,亚硒酸钠用量与大豆籽粒硒含量呈显著或者极显著正相关。8个大豆品种籽粒硒含量均值随亚硒酸钠用量的增加呈上升趋势,与CK相比,C1～C4处理均能极显著提高8个大豆品种籽粒硒含量均值,提高了571.186 %～2 489.831%。亚硒酸钠用量对大豆籽粒硒含量的影响大于大豆品种对大豆籽粒硒含量的影响。喷施亚硒酸钠用量（X）与每种用量下8个大豆籽粒硒含量均值（Y -均）的直线回归方程为Y -均=0.012X+0.003,r =0.986,达到极显著正相关。根据该方程,当大豆籽粒硒含量达到富硒大豆标准（0.1～1 mg/kg）,喷施亚硒酸钠用量的范围为8.08～83.08 g/hm²。分析喷施亚硒酸钠用量与大豆籽粒硒含量的回归方程发现,郑9525的回归方程斜率最大,C4处理中籽粒硒含量达到最大值1.997 mg/kg,籽粒富集硒能力最强;齐黄34斜率最小,C4处理中籽粒硒含量达到最小值1.133 mg/kg,籽粒富集硒能力最弱。在本试验条件下,喷施亚硒酸钠对大豆单株产量没有显著影响。大豆品种对单株产量的影响大于亚硒酸钠用量对单株产量的影响。     

壳聚糖/海藻酸钠微球对红景天苷控制释放的研究

将含有药物的海藻酸钠溶液滴入到壳聚糖和氯化钙的混合溶液中形成微球,制备一系列红景天苷微球,研究微球对红景天苷的包载能力及释药特性。结果表明:海藻酸钠、氯化钙、壳聚糖的质量浓度、海藻酸钠与红景天苷的比例及壳聚糖溶液pH值对微球的包埋率、载药率及缓释性能有影响,而成膜反应时间对载药率和包埋率有影响,对缓释性能没有影响。缓释效果最佳的微球制备工艺条件为海藻酸钠与红景天苷质量比为1.5,海藻酸钠2.5 g/mL,壳聚糖0.8 g/mL,氯化钙1.5 g/mL,成膜时间为5 min,pH值为5.5。