Paper replication method for isolation of radiation-sensitive mutants.

A filter paper replication system particularly useful for isolation of radiation-sensitive mutants of pigmented bacteria was devised. The fidelity of replication was high. Adhesion between a paper disk and a properly dried master plate provided adequate contact pressure. The replicas arising from this technique constitute a convenient apparatus for general application in isolation of clones sensitive to a discriminating treatment.     

Studies on the Indochina I/CDC strain of Plasmodium falciparum in Colombian and Bolivian Aotus monkeys and different anophelines

The Indochina I/CDC strain of Plasmodium falciparum was isolated from a physician returning to the United States after working in the refugee camps along the Thailand-Kampuchean border. The strain was established in splenectomized Aotus monkeys from Colombia after being grown in vitro for 50 days. During the first three passages in Colombian monkeys, the parasites were not infective to Bolivian Aotus monkeys. After six intervening passages in Saimiri sciureus monkeys, the parasites produced high parasitemias in both Colombian and Bolivian Aotus, but gametocytes were no longer produced. Mosquito infections were obtained only during the first three passages in the Colombian monkeys. The most susceptible mosquito was Anopheles freeborni, followed by An. dirus, An. stephensi, An. maculatus, An. culicifacies, and, rarely, An. gambiae. Sporozoites were found in the salivary glands of the An. freeborni, An. dirus, An. stephensi, and An. maculatus.     

Studies of the Sal I strain of Plasmodium vivax in the squirrel monkey (Saimiri sciureus)

The Sal I strain of Plasmodium vivax was successfully adapted to three phenotypes of the squirrel monkey, Saimiri sciureus. Through five linear blood passages, parasitemias in excess of 200,000/mm3 blood were attained; Bolivian phenotype Saimiri appear to develop higher peak parasitemias. Sporozoites of the Sal I strain inoculated intravenously produced patent parasitemias in all five squirrel monkeys challenged, with prepatent periods ranging from 21 to 38 days. Anopheles freeborni and An. gambiae were the most susceptible of eight anopheline species fed on infected squirrel monkeys. As a model for in vivo studies of P. vivax the Sal I strain in Saimiri has great potential.     

The proteolytic digestion of ox neurofilaments with trypsin and alpha-chymotrypsin.

Brief digestion of ox neurofilaments with trypsin liberates fragments that are soluble and have molecular weights ranging from 164 000 to 97 000. Peptide fingerprinting indicates that these regions, termed the tryptic head-regions, arise from the 205 000- and 158 000-mol.wt. components of the triplet. The remains of the parent polypeptides sediment with normal filaments and have been termed tail-regions. Digestion of neurofilaments with chymotrypsin also liberates soluble fragments (chymotryptic head-regions) but these have mol.wts. 171 000 and 119 000, though they too originate from the higher-molecular-weight triplet polypeptides. Tryptic and chymotryptic head-regions have extensive homology, and a low (less than or equal to 20%) helix content. Electron microscopy shows that chymotryptic digestion rapidly reduces the length of filaments, probably because this enzyme preferentially attacks the 72 000-mol.wt. polypeptide. In contrast, brief digestion with trypsin does not reduce filament length even though more than 90% of the two higher-molecular-weight components have been cleaved. These results indicate that the backbone of native filaments is formed from the 72 000-mol.wt. polypeptide together with the tail-regions from the 205 000- and 158 000-mol.wt. polypeptides. The corresponding head-regions of these components, which can represent nearly 75% of each molecule, are not necessary for preserving the backbone of native neurofilaments and are therefore good candidates for being the side arms that connect these filaments in nerve cells.     

Postural influence on maternal capillary oxygen and carbon dioxide tension

The effect of posture on maternal capillary blood Po₂ and Pco₂ was studied in pregnant and non-pregnant women. There was a significant decrease of Po₂ (mean 13·0 mm. Hg) and significant decrease of Pco₂ (mean 2·4 mm. Hg) when pregnant women sat up, but these changes did not occur in the non-pregnant. These findings may be relevant to debate on the optimum posture for labour.     

L-乳酸脱氢酶热变性的热力学研究

用差示扫描量热法对L-乳酸脱氢酶的热变性进行了研究(温度扫描范围为290—390K,酶蛋白溶液浓度为0.28—0.72mg蛋白/mg溶液)。实验观察到当酶溶液浓度在0.62—0.72mg蛋白/mg溶液范围内有一个吸热转变,酶溶液浓度小于0.62mg蛋白/mg溶液时有两个未完全分开的吸热转变。 这个酶的量热焓与范德霍夫焓的比远大于1,而接近于2,这表明乳酸脱氢酶的变性过程不是一个简单的两态转变,从热力学和吸热峰的形状、大小分析,可以推断乳酸脱氢酶分子是由两个以弱相互作用相连结的合作结构区组成,而每一个结构区是由两个相互作用很强的亚基组成。也就是说乳酸脱氨酶的变性过程包括两个半独立的合作结构区的转变,每一个结构区的转变都近似一个两态转变,ΔHeal与ΔHvh的比值是随着两个半独立部分相互作用的增强,即蛋白浓度的增加而减小。随着蛋白浓度的减小,蛋白质周围水分子增多,酶分子中两个半独立部分的相对独立性增强,这可由热谱图上一个吸热转变变成两个半独立的转变得到证实。     

化学诱导的B95-8细胞中TK酶的分离和性质研究

巴豆油和正丁酸钠(nSB)诱导Raji和B95-8细胞株生成胸腺嘧啶核苷激酶(TK),其粗提液,经DEAE—纤维素柱层析,可分成两个性质不同的TK活性峰—峰Ⅰ和峰Ⅱ:(1)峰Ⅰ是穿过峰,峰Ⅱ为洗脱峰,在120mMol/L从K_2HPO_4缓冲液时洗脱下来;(2)峰Ⅱ含量在病毒生产性细胞B95-8中高于非生产性的Raji细胞;(3)B95-8细胞经联合诱导48小时后,峰Ⅱ比活性最高;(4)TTP对峰Ⅰ和峰Ⅱ的抑制效应不同,两峰利用GTP能力也不同;(5)PAGE结果表明:峰Ⅰ的Rm值为0.044,峰Ⅱ呈现两条带,Rm值分别为0.015和0.276;(6)峰Ⅰ的Km值为0.86μMol/L,峰ⅡKm值为0.29μMol/L。根据以上的结果,我们认为:峰Ⅰ是细胞TK(C-TK),而峰Ⅱ具有许多疱疹病毒TK的特性,因此,峰Ⅱ是EB病毒相关TK(EBV-TK)。     

The efficacy of biobehavioral and compliance interventions in the adjunctive treatment of mild pregnancy-induced hypertension

This investigation assessed the efficacy of a biobehavioral intervention in the adjunctive treatment of mild pregnancy-induced hypertension (PIH), a potentially serious complication of pregnancy in which normotensive women develop hypertension, proteinuria, and edema of unknown etiology late in gestation. Forty-five women with symptoms of PIH were randomly assigned to one of three treatment conditions: bed rest alone (the most common obstetrical treatment), bed rest with individualized compliance enhancement training, or a four-session biobehavioral treatment consisting of bed rest, compliance enhancement training, and individualized thermal biofeedback-assisted relaxation training. Results indicated that while blood pressure for the bed rest and compliance enhancement groups continued to rise and pose an increasing health risk to maternal and fetal well-being, subjects in the biobehavioral group maintained their blood pressure at a significantly lower, and presumably safer, level. The biobehavioral treatment is hypothesized to affect blood pressure levels in subjects with mild PIH through the mediation of the sympathetic nervous system, decreasing peripheral vascular resistance and cardiac output. The results of this investigation suggest that the biobehavioral intervention may be an effective adjunct to bed rest in the treatment of mild PIH remote from term.