An isolated rat lung perfusion system for use in tobacco smoke studies

An isolated rat lung perfusion system has been developed for use in tobacco smoke studies. The lungs are ventilated by means of subatmospheric (negative) pressure produced through operation of an artificial thorax. The system enables standard respiratory conditions to be employed and so eliminates variations in animal breathing characteristics. The various tests of viability which have been carried out have shown that the preparations are viable for periods of at least 1 hr. It was also demonstrated that transfer of 14C-nicotine from smoke to perfusate was rapid and linear over the period of smoke exposure and that first-pass metabolism of nicotine was of little significance.     

An autoradiographic study on the localization of 131I-labeled thyroid hormones in the tissues of the pig

Autoradiographic studies on the localization of 131I-labeled thyroxine and triiodothyronine in the various organs and tissues of the pig have been conducted. The isotopes were compared as to the intensity of radioactivity on the basis of the concentration of developed silver grains in the tissues following the respective radioactive hormone injections. In general, for an identical dose of the isotope and with analogous processing procedures, the autoradiographs of most of the tissues after triiodothyronine were relatively more radioactive than after thyroxine. In both the hormone treatments, the tissues from younger pigs were relatively more radioactive than the tissues of older pigs. The various tissormones. Based on differential localization of radioactivity, the pigs excreted more radioiodine through bile, pancreatic and salivary secretions and in urine.     

Intracranial chondromas

Biochemical and hormonal effects of oral calcium supplementation in premature and asphyxiated neonates during the first few days of life are described. Eight pairs of infants were matched for gestational age and one-minute Apgar score. One member of each pair served as a control and the other was given supplemental oral calcium (75 mg/kg/24 hr) beginning at 12 and ending at 72 hours of age. The supplemental infants had significantly higher serum calcium values both during the time of supplementation and for 36 hours after supplementation was stopped. The oral calcium supplements had no significant effect on serum concentrations of phosphate, magnesium, 25-hydroxy-vitamin D3, or parathyroid hormone, The incidence of hypocalcemia after 12 hours of age was 0 in eight supplemented infants and three in eight control infants. In patients at risk for hypocalcemia, prospective use of oral calcium supplements during the period when there is inadequate calcium intake from feedings may prevent hypocalcemia, appears to be without deleterious effect on measurable chemical and hormonal factors important in calcium homeostasis, and results in maintenance of higher serum calcium levels after supplementation has been discontinued.     

Penicillin transport from cerebrospinal fluid

The passage of penicillin G from cerebrospinal fluid (CSF) was studied by continuous ventriculocisternal perfusion in conscious rabbits. The concentration of penicillin G in the perfusate, collected from the cisterna magna, was 76.5 percent +/- 1.0 (SEM) of that entering the ventricles (having adjusted for normal secretion of CSF). The mean concentration of penicillin G rose 15 percent (p less than 0.005) in the cisternal CSF after probenecid (2 mg per milliliter) was added to the perfusion fluid. We conclude that an active transport system removes penicillin G from the CSF; this mechanism can be inhibited by intraventricular probenecid. Our results are in accord with observations deriving from studies on anesthetized animals given probenecid intravenously or intraperitoneally.     

Radioimmunossay of secretin in human plasma

A radioimmunoassay is presented which employs 125I-labelled synthetic secretin, antibody against synthetic secretin, and standards prepared from pure natural porcine secretin. Secretin to be measured was extracted into methanol from heparinized plasma containing aprotinin, which together with cysteine hydrochloride was used as stabilizer throughout the assay. With polyethylene glycol separation, a within assay precision of 10% at 17 pmol/1 was found. The between assay precision was 15% at 17 pmol/1 and thelimit of detection 2.5 pmol/1 plasma. Accuracy was 70-85%. The immunoreactive secretin levels in human plasma increased from 4.5+/-0.5 pmol/1 (mean+/-S.E.M.) to 19.5+/-7.5 pmol/1 (mean+/-S.E.M.) after duodenal acidification (n=5). Pancreatic flow rate increased from 0.5+/-0.1 ml/min (mean+/-S.E.M.) to 4.8+/-0.5 ml/min (mean+/-S.E.M.), and bicarbonate output from 9.6+/-1.8 mumol/min (mean+/-S.E.M.) to 268+/-51 mumol/min (mean+/-S.E.M.) after duodenal acidification.     

Production and characteristics of glycerin mutants of S. typhimurium

S. typhimurium glycerine mutants-gly 90 and gly 87 were obtained under the action of ethylmethanesulfonate. The mutants obtained were characterized by the site of block in the course of glycerine utilization:gly 90 mutant bore the mutation in the glp K-gene, this leading to the defect by glycerokinase-the enzyme of the first stage of glycerine metabolism; gly 87 mutant had derangements in the other stage of glycerine utilization. Both mutants lost their capacity to induce keratoconjunctivitis in guinea pigs, but differed by the LD50 value in intraperitoneal infection of albino mice (y gly 87--5 cells, y gly 90--1x10(7) cells).     

myo-Inositol metabolism during lactation and development in the rat. The prevention of lactation-induced fatty liver by dietary myo-inositol

Effects of dietary myo-inositol deprivation were examined during prenatal and postnatal development and during lactation in the rat. The deficient diet contained no detectable myo-inositol while the supplemented diet contained 0.5% (w/w) myo-inositol while the supplemented diet ct contained 0.5% (w/w) myo-inositol at the expense of sucrose. Both diets contained 25% casein, adequate amounts of all known vitamins, choline, and essential fatty acids as well as 0.5% (w/w) phthalylsulfathiazole to depress myo-inositol contribution to the diet by microorganisms. Pregnant rats of the Holtzman strain were fed the respective diets during gestation and lactation, and pups were fed the corresponding diet after weaning until 3 months of age. There were no significant differen-es in body weight between experimental groups. Supplementation of the diet with myo-inositol significanly increased the levels of myo-inositol in plasma, liver, kidney, and intestine of pups at all ages examined, and significantly increased the levels of myo-inositol in the milk and mammary tissue during lactation. During lactation, the myo-inositol deprived dams developed severe fatty livers (31% w/w) characterized by diminished phosphatidyl-inositol (50%) and total phospholipid phosphorus (57%) levels as compared with controls. After weaning, the liver lipid content of the myo-inositol deprived dams returned to normal (4.5%). The data suggest that a possible threshold level of free myo-inositol (approximately 0.15 mumoles/g lipid-free tissue) was required to prevent fatty liver in lactating dams under these dietary conditions. Effects of the deficient diet on fertility were also examined. Based on sperm count and production of offspring, there were no differnences between the experimental and control males. Females of both groups showed equal ability to produce offspring.     

正交空时分组码性能估计的一种方法

本文给出并证明了采用正交空时分组码传输的衰落信道条件下,接收机输出瞬时信噪比的一般表达形式,分析了瑞利衰落信道条件下接收机输出符号差错性能.给出了正交空时分组码的符号差错概率的最小距离球界,由此可以得到空时分组码关于发送天线数量的"地板效应".     

关于三门峡水库若干问题认识与思考

对三门峡水利枢纽工程四十年来的原建、增建、改建过程做了系统回顾和合理划分,对枢纽工程运用探索在有关重点问题进行了综合分析,认为综过增、改建过程和按“蓄清排浑”控制运用后,基本上实现了1969年“四省会议”原定目标,并就小浪底工程投运引起的条件变化,来水来沙变化和三门峡水利枢纽自身运用条件变化,对三门峡水库今后提出了几点参考意见。     

Crack growth predictions in a complex helicopter component under spectrum loading

Fatigue crack growth predictions have been made on a helicopter round‐robin crack configuration. The crack configuration was a small corner defect at the edge of a large central hole in a flanged plate made of 7010 aluminium alloy and the component was subjected to a simulated helicopter spectrum loading. The crack growth rate data and the stress‐intensity factor (K) solution for the crack configuration were provided in the round‐robin. The FASTRAN life‐prediction code was used to predict fatigue crack growth under various load histories on the aluminium alloy, such as Rotorix and Asterix, on both compact tension C(T) specimens and the complex crack configuration. A BEASY three‐dimensional stress‐intensity factor solution for the round‐robin problem was also provided for this paper and is compared with the original K solution. Comparisons are made between measured and predicted fatigue crack growth lives for both crack configurations. The predicted lives for the C(T) specimens were 15–30% longer than the measured lives; and crack growth in the round‐robin configuration agreed very well in the early stages of crack growth, but the life was 30% short of the test results at the final crack length.