玻璃纤维滤纸型气溶胶中~(210)Pb、~(210)Po的同时测定方法

试验介绍了用铜箔自沉积镀片方法同时测定气溶胶中210Pb和210Po放射性活度。针对玻璃纤维滤纸型气溶胶提出了全溶法和浸洗法。并对两种方法测量结果进行比对,测量结果显示,全溶法测量结果比浸洗法结果高10%以上,测量结果准确度更高。     

镍镀片富集 α、β粒子计数法同时测定岩石及土壤中的210Pb、210Bi、210Po

提出以Ni箔为镀片富集210Bi、210Po,以α、β粒子计数法同时快速测定岩石、土壤样品中210Pb、210Bi、210Po的分析方法。通过对制源溶液的酸度、体积、温度及还原剂的优化选择,有效地消除了可能存在的共存元素和同位素的干扰,自镀时间缩短至40 min。在最佳条件下,建立了210Po、210Bi、210Pb的校准曲线,其相关系数在0998 3～0999 7之间,线性范围在10×10-3~10×102 Bq之间,210Po、210Bi、210Pb的检出限分别为 6×10-4 Bq/g、6×10-3 Bq/g、6×10-3Bq/g,方法的测试精度(RSD,n=11)优于16%,样品加标回收率在95%~105 %之间,实现了岩石及土壤中210Pb、 210Bi、210Po的同时测定。     

Prediction of vertebral and femoral strength in vitro by bone mineral density measured at different skeletal sites

The aim of the present study was to investigate the prediction of vertebral and femoral strength in vitro by bone mineral density (BMD) measured at different skeletal sites. The third lumbar vertebral body, the right proximal femur, and the right calcaneus were removed from 38 male and 32 female cadavers (mean age 69 years, range 23-92 years). Areal BMD of all bone specimens was determined by dual-energy X-ray absorptiometry (DXA). The failure load of the vertebral body and the femur was determined by mechanical testing. Vertebral and femoral strength were both greater in males than females (p < 0.01), as was BMD at all sites (p < 0.01). Vertebral strength correlated well with vertebral BMD (r2 = 0.64) but was only moderately correlated with BMD measured at the femur (r2 = 0.36) or the calcaneus (r2 = 0.18). Femoral strength showed the highest correlations with femoral BMD (r2 = 0.88) and somewhat weaker relationships with BMD at the vertebra (r2 = 0.50) and the calcaneus (r2 = 0.54). BMD values at the vertebra, femur, and calcaneus were only moderately interrelated (r2 = 0.31-0.65), and vertebral strength correlated only modestly with the strength of the femur (r2 = 0.36). These in vitro results support the concept that optimal prediction of vertebral or femoral strength by DXA requires site-specific assessments.     

Elastic properties of human cortical and trabecular lamellar bone measured by nanoindentation

An experimental investigation was undertaken to measure the intrinsic elastic properties of several of the microstructural components of human vertebral trabecular bone and tibial cortical bone by the nanoindentation method. Specimens from two thoracic vertebrae (T-12) and two tibiae were obtained from frozen, unembalmed human male cadavers aged 57 and 61 years. After drying and mounting in epoxy resin nanoindentation tests were conducted to measure Young's modulus and the hardness of individual trabeculae in the vertebrae and single osteons, and interstitial lamellae in the tibiae. Measurements on the vertebral trabeculae were made in the transverse direction, and the average Young's modulus was found to be 13.5 +/- 2.0 GPa. The tibial specimens were tested in the longitudinal direction, yielding moduli of 22.5 +/- 1.3 GPa for the osteons and 25.8 +/- 0.7 GPa for the interstitial lamellae. Analysis of variance showed that the differences in the measured moduli are statistically significant. Hardness differences among the various microstructural components were also observed.     

The levels of main urinary metabolite of prostaglandin F1alpha and F2alpha in human subjects measured by radioimmunoassay

Previous researchers have suggested that TMR children lack the competence to process negation. Questions about the appropriateness of using reversible sentences to test comprehension and observations on TMR children's imitative processing of simple affirmative and negative sentences led to an experimental reexamination of the earlier findings. Institutionalized students ranging in age from 10 to 21 years with a mean IQ of 30 were asked to evaluate 16 picture pairs, 8 each for nonreversible and reversible sentences. Nonreversible sentences, both positive and negative, were interpreted correctly more often than reversible sentences. There was a significant correlation between comprehension and mental age. The results were interpreted as substantiating the adverse effect of sentence reversibility on comprehension and as evidence for the position that retarded children develop basic grammatical structures including negation at a relatively late age, but in normal interrelationship and sequence with other language and cognitive abilities.     

Lipopolysaccharide and IL-1 alpha activate CNS pathways as measured by NK cell activity

An outward current (Iout) was produced by stereoisomers of beta-hydroxy-L-glutamic acid (L-BHGA), an L-glutamic acid (L-Glu) derivative, applied by brief pneumatic pressure ejection on an identifiable neurone type, v-LCDN (ventral-left cerebral distinct neurone), of Achatina fulica Férussac. However, L- and D-Glu were almost ineffective on this neurone type. The pharmacological features of this Iout caused by L-BHGA were elucidated in the present study. According to the dose (pressure duration)-response studies on the L-BHGA stereoisomers that produced the Iout, the effective potency of threo-L-BHGA was approximately similar to that of erythro-L-BHGA. The dose (pressure duration)-response curve of quisqualic acid was shifted towards the left direction from those of threo-and erythro-L-BHGA, suggesting that the binding activity of quisqualic acid to the receptors would be stronger than those of the L-BHGA stereoisomers. GABA, glycine and L-homocysteic acid showed an inward current (Iin) on this neurone type, in contrast to the Iout caused by L-BHGA. beta-Alanine and taurine had absolutely no effect. Therefore, no amino acid inhibitory neurotransmitter candidate was found for this neurone type except for L-BHGA. It was assumed that L-BHGA, in either threo-or erythro-configuration, would be an inhibitory neurotransmitter for this neurone type. Mammalian L-Glu receptor antagonists. D(-)-AP-5, (+/-)-CPP, CNQX and L(+)-AP-3, applied by perfusion, showed no effect on the Iout of v-LCDN caused by threo-L-BHGA, indicating that the features of the inhibitory receptor activated by L-BHGA were much different from those of any type of the mammalian L-Glu receptors. Among the inhibitors of ATP-sensitive K+ channel, glipizide significantly inhibited the Iout caused by threo-L-BHGA, whereas tolbutamide did not. Inhibitors of intracellular signal transduction systems, H-7, H-8, H-9, staurosporine, calphostin C, KT5823 and W-7, had no effect on the Iout caused by threo-L-BHGA, suggesting that the receptors activated by threo-L-BHGA would be ionotropic.     

Redox behavior of cytochrome oxidase in the rat brain measured by near-infrared spectroscopy

Using near-infrared spectroscopy, we developed a new approach for measuring the redox state of cytochrome oxidase in the brain under normal blood-circulation conditions. Our algorithm does not require the absorption coefficient of cytochrome oxidase, which differs from study to study. We employed this method for evaluation of effects of changes in oxygen delivery on cerebral oxygenation in rats. When fractional inspired oxygen was decreased in a stepwise manner from 100 to <10%, at which point the concentration of oxygenated hemoglobin ([HbO2]) decreased by approximately 60%, cytochrome oxidase started to be reduced. Increases in arterial PO2 under hyperoxic conditions caused an increase in [HbO2], whereas further oxidation of cytochrome oxidase was not observed. The dissociation of the responses of hemogloblin and cytochrome oxidase was also clearly observed after the injection of epinephrine under severely hypoxic conditions; that is, cytochrome oxidase was reoxidized with increasing blood pressure, whereas hemoglobin oxygenation was not changed. These data indicated that oxygen-dependent redox changes in cytochrome oxidase occur only when oxygen delivery is extremely impaired. This is consistent with the in vitro data of our previous study.