Sul meccanismo di azione della streptomicina

Summary A study was undertaken on the variations of the redox potential level produced by streptomycinin vitro andin vivo. We have been able to show that, owing to an oxidative effect, streptomycin produces an increase of the redox potential level. This oxidative effect varies in degree according to the condition of the patient.We also found that in the blood and in the spinal fluid of patients suffering from tubercular meningitis factors are present which inhibit the action of streptomycin.The results of our findings lead to the conclusion that the dose of streptomycin must be varied according to the condition of the patient if the constant level required for an efficient therapy is to be maintained in the blood and in the spinal fluid.     

In vivo effects of immunostimulating lipopeptides on mouse liver microsomal cytochromes P-450 and on paracetamol-induced toxicity

Summary Immunomodulating lipopeptides lauroyl-L-Ala--D-Glu-LL-A2pmNH2-Gly (RP 44.102) and lauroyl-L-Ala--D-Glu-LL-A2pmNH2 (RP 56.142) were found to protect mice against the hepatotoxicity of paracetamol, which is due to cytochrome P-450 dependent formation of toxic metabolites and radicals. In fact they decreased the amount of hepatic microsomal cytochrome P-450, and the level of CCl₄-induced lipid peroxidation. In contrast lauroyl-L-Ala--D-Glu-DD-A2pmNH2 (RP 53.204), which only differs by the configuration of the two chiral carbons of A2pm (diaminopimelic acid) and is not an immunomodulating agent, failed to protect against poisoning by paracetamol and had no effect on the level of hepatic cytochrome P-450 or the microsomal CCl₄-induced lipid peroxidation. This provides a clear connection between the immunostimulating properties of a compound and its effects on xenobiotic biotransformations.     

耐热碱性磷酸酯酶基因的亚克隆及其在大肠杆菌中的表达

根据耐热碱磷酸酯酶基因的酶切图谱和ＤＮＡ序列,分别在基因的起始密友子和终止密码子设计２个突变引物。引物的５‘端分别带有ＮｄｅⅠ和ＢａｍＨⅠ酶切全点。通过ＰＣＲ从质粒ｐＴＡＰ１１８Ｂ中扩增获得了ＦＤ－ＴＡＰ基因的全序列。经过酶切将基因亚克隆于高达载体ｐＪＬＡ５０３。     

Variations au cours de la journée de l'incorporation in vivo de la leucine tritiée dans les protéines du cervelet et du cerveau du jeune rat normal et hypothyro?dien. Daily variations of the in vivo [3H] leucine incorporation into the cerebellar and cerebral proteins of the normal and hypothyroid young rat [(author's transl)

In the normal and hypothyroid 6-day-old rat, the specific radioactivity (RSA) and the relative RSA (ratio of the RSA to the [3H] lecine concentration of the acido soluble phase) of the cerebral and cerebellar proteins, changes during the day synchronally. They show a maximum at 15.00 h and a minimum at 0.300 h. At all stages studied, these values are significantly lower in the hyothyroid animals than in normal ones.     

Nucleolus organizer region location and ‘ring’ chromosomes in the bharal

Summary Silver-staining has been used to identify the nucleolus organizer regions (NORs) in the bharal. These show homology with sheep, goat, cattle and aoudad. The association of the NORs on both telomeres of chromosome 3 results in a ring chromosome.     

输入具有饱和非线性的离散系统闭环稳定性

基于矩阵范数和离散时间系统李雅普诺夫定理，给出了控制输入具有饱和非线性特性的状态反馈控制系统的闭环渐近稳定性判据，并用算例验证了基本原理的正确性。     

西藏黄牛血清淀粉酶（Am）、酯酶（Es）同工酶遗传特性的研究

应用聚丙烯酰胺凝胶电泳法研究了西藏黄牛的Ａｍ和Ｅｓ同工酶，得出了其基因频率和基因型频率．结果表明，西藏黄牛的Ａｍ和Ｅｓ两个同工酶位点的基因分布及其频率与瘤牛种（Ｂｏｓｉｎｄｉｃｕｓ）差异较大，而与普通牛种（Ｂｏｓｔａｕｒｕｓ）较为一致，这进一步从同工酶位点上验证了我们对西藏黄牛的Ｙ染色体特征和血液蛋白多态性的研究结果     

木糖－BZ体系化学振荡反应的研究

首次报道了ＢｒＯ３－－木糖－丙酮－Ｍｎ（２＋）－Ｈ２ＳＯ４体系统的化学振荡反应，测定了振荡反应的条件和典型的振荡波形，研究了反应物浓度，Ｃｌ－，Ｂｒ－，Ａｇ＋及丙烯腈等各种因素对振荡反应的影响，测定了温度对振荡诱导期，振荡周期的影响，并由此计算得到振荡反应的表观活化能．研究了各金属离子对振荡反应的影响以及Ｍｎ（２＋）的催化作用．考察了Ｎ２流代替丙酮时的振荡现象，从而对丙酮在振荡反应中的作用作了说明．分析了振荡反应的产物，并测定了体系中ＢｒＯ３－和木糖反应的化学计量关系，对振荡反应机理作了初步的探索．