眼镜蛇科蛇毒对S180,EAC腹水癌治疗作用研究

本文报道金环蛇、扁颈蛇、眼镜蛇、银环蛇蛇毒及其细胞毒对小鼠S180,EAC腹水癌的治疗作用。结果表明,蛇毒及其细胞毒在体外有明显杀灭癌细胞作用,体内有较明显的治疗作用,动物存活时间延长,接种率降低。肿瘤细胞呈现不同程度形态变化,主要为膜破裂,坏死等。治疗效应由强到弱为金环蛇毒,扁颈蛇毒,金环蛇细胞毒,眼镜蛇毒,眼镜蛇细胞毒。银环蛇毒无作用。     

Higher order structure is present in the yeast nucleus: autoantibody probes demonstrate that the nucleolus lies opposite the spindle pole body

A panel of sera from 892 autoimmune patients was screened by indirect immunofluorescence on mammalian cells. Seventy-three sera were identified that recognize the nucleolus. Three of these sera appear to stain the nucleolus in yeast, suggesting that they recognize highly conserved antigens. These three sera also immunoprecipitate mammalian U3 snRNA-containing particles, which reside in the nucleolus and have been implicated in rRNA processing. Double immunofluorescence experiments with anti-nucleolus and anti-tubulin antibodies revealed a novel form of non-random nuclear organization in yeast. The spindle pole body and the nucleolus — both of which are associated with the nuclear envelope — preferentially localize at opposite ends of the nucleus. Organization of these and other components into specific regions of the nucleus may be important for optimizing their proper function.     

High-dose mode of death in Tribolium

This study reports the first demonstration within a single insect genus (Tribolium) of both the acute, or lethal-midlethal, dose-independent pattern of mortality, and the hyperacute, dose-dependent pattern, after appropriate doses of ionizing radiation. This demonstration provides resolution of apparently contradictory reports of insect responses in terms of doses required to cause lethality and those based on survival time as a function of dose. A dose-dependent mortality pattern was elicited in adult Tribolium receiving high doses, viz., 300 Gy or greater; its time-course was complete in 10 days, before the dose-independent mortality began. Visual observations of heavily-irradiated Tribolium suggested neural and/or neuromuscular damage, as had been previously proposed by others for lethally-irradiated wasps, flies, and mosquitoes. Results of experiments using fractionated high doses supported the suggestion that the hyperacute or high-dose mode of death is the result of damage to nonproliferative tissues. Relative resistance of a strain to the hyperacute or high-dose mode of death is not necessarily correlated with resistance to the midlethal mode, which is believed to be the result of damage to the proliferative cells of the midgut.

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Résumé Les résultats de nombreuses études des réactions des insectes adultes de différents groupes à l'irradiation s'opposent quant à l'importance de la dose provoquant la létalité et quant aux modalités de la mort. Les diptères et les guèpes impliquent des doses très élevées,-des centaines de Gy-, ne présentent aucune période caractérisant la mort par irradiation, et décèdent de plus en plus tôt avec l'augmentation des doses. Beaucoup d'autres insectes succombent à des doses (milétalelétale) beaucoup plus faibles,-de quelques Gy à des dizaines-, et quelle que soit la dose meurent au bout d'un temps voisin.Au cours de cette étude, nous avons pu observer que ces deux types de mortalité peuvent être provoqués chez le même genre d'insecte (Tribolium), avec des doses convenables d'irradiation . Un syndrôme caractéristique a été provoqué avec des doses très élevées, de 300 Gy ou plus,-à ces doses la mort est obtenue en 10 jours après l'irradiation. L'absence de syndrôme caractéristique se produit avec des doses inférieures ou égales à 80 Gy; la mort a lieu alors entre 10 et 16 jours en fonction de la dose.Les différences entre les deux types de décès indiquent deux processus de mort par irradiation. La manifestation d'une désorientation et d'une perte de coordination motrice chez les Tribolium fortement irradiés suggère des altérations neurales et/ou neuromusculaires comme cause/s de ce type de mort provoquée par des doses élevées. L'implication de tissus sans prolifération a été confortée par les résultats d'expériences utilisant de hautes doses fractionnées. Le type de mort milétal est considéré après de nombreuses observations indépendantes, comme le résultat d'atteintes à la prolifération des cellules de l'intestin moyen.Les données contradictoires sur les réactions des insectes aux irradiations proviennent d'abord de l'absence de connaissances sur le lieu des dégâts. Les diptères sont connus maintenant, après différentes études, comme perdant complètement l'aptitude au renouvellement cellulaire, et présentent ainsi un type de mort avec dose élevée. Beaucoup d'autres insectes adultes ont un renouvellement cellulaire de l'intestin moyen limité, et ainsi présentent le type de mort milétal. Le type de mort, dit haute dose, peut être induit dans cette dernière catégorie d'insectes par une irradiation suffisamment forte, et, dans le cas du Tribolium le déroulement de la mort se produit alors de deux façons bien distinctes.

     

Nonparametric confidence interval estimators for heritability and expected selection response

Statistical methods have not been described for comparing estimates of family-mean heritability (H) or expected selection response (R), nor have consistently valid methods been described for estimating R intervals. Nonparametric methods, e.g., delete-one jackknifing, may be used to estimate variances, intervals, and hypothesis test statistics in estimation problems where parametric methods are unsuitable, nonrobust, or undefinable. Our objective was to evaluate normal-approximation jackknife interval estimators for H and R using Monte Carlo simulation. Simulations were done using normally distributed within-family effects and normally, uniformly, and exponentially distributed between-family effects. Realized coverage probabilities for jackknife interval (2) and parametric interval (5) for H were not significantly different from stated probabilities when between-family effects were normally distributed. Coverages for jackknife intervals (3) and (4) for R were not significantly different from stated coverages when between-family effects were normally distributed. Coverages for interval (3) for R were occasionally significantly less than stated when between-family effects were uniformly or exponentially distributed. Coverages for interval (2) for H were occasionally significantly less than stated when between-family effects were exponentially distributed. Thus, intervals (3) and (4) for R and (2) for H were robust. Means of analysis of variance estimates of R were often significantly less than parametric values when the number of families evaluated was 60 or less. Means of analysis of variance estimates of H were consistently significantly less than parametric values. Means of jackknife estimates of H calculated from log transformed point estimates and R calculated from untransformed or log transformed point estimates were not significantly different from parametric values. Thus, jackknife estimators of H and R were unbiased. Delete-one jackknifing is a robust, versatile, and effective statistical method when applied to estimation problems involving variance functions. Jackknifing is especially valuable in hypothesis test estimation problems where the objective is comparing estimates from different populations.     

Assay of L-3-hydroxyacyl-coenzyme A dehydrogenase with substrates of different chain lengths

A method for assaying L-3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) which permits rate measurements with L-3-hydroxyacyl-CoA substrates of various chain lengths at physiological pH is described. The method is based on a coupled assay system in which 3-ketoacyl-CoA compounds formed by the dehydrogenase are cleaved by 3-ketoacyl-CoA thiolase (EC 2.3.1.16) in the presence of CoASH. The advantages of this assay method are its irreversibility and elimination of product inhibition. The assay procedure was used to determine the kinetic parameters (Km, Vmax) of pig heart L-3-hydroxyacyl-CoA dehydrogenase with several substrates of various chain lengths. The data obtained show the enzyme to be most active with medium-chain substrates whereas Km values for medium-chain and long-chain substrates are almost equal but much lower than those previously reported.     

2-ketoacid dehydrogenase complexes of Escherichia coli: stereospecificities of the three components for (R)-lipoate

Stereospecificities of component enzymes in the pyruvate dehydrogenase complex and 2-ketoglutarate dehydrogenase complex from Escherichia coli for lipoate and dihydrolipoate are determined. Assays of the component enzymes using R,S-, R-, or S-lipoate or the enantiomers of dihydrolipoate show that only the R-enantiomers are substrates for these enzymes. Nonenzymatic reactions involving acetyl group transfer and coupled electron and acetyl group transfer between enantiomeric molecules of lipoate or/and dihydrolipoate proceed at significant rates. Coupled acetyl group and electron transfer from enzyme-bound acetyldihydrolipoyl moieties to free lipoate is also observed. The S-enantiomers are neither substrates nor inhibitors; however, products of S-enantiomers are slowly generated in enzymatic reactions owing to nonenzymatic reactions between enzyme-bound acetyldihydrolipoyl-groups and free S-lipoate or S-dihydrolipoate.     

The effect of crosslinking by bis(3,5-dibromosalicyl) fumarate on the autoxidation of hemoglobin

Bis(3,5-dibromosalicyl) fumarate was used to crosslink hemoglobin both in the oxy and deoxy states. This double headed diaspirin was known to crosslink oxy Hb A selectively between Lys 82 beta 1 and Lys 82 beta 2 (Walder, J. A., et al. (1979) Biochemistry 18, 4265) and deoxy Hb A between Lys 99 alpha 1 and Lys 99 alpha 2 (Chatterjee R. Y., et al. (1986) J. Biol. Chem. 261, 9929). The autoxidation at 37 degrees C of oxy alpha 99 crosslinked hemoglobin was found to be 1.8 times as fast as that of Hb A while that of the oxy beta 82 crosslinked hemoglobin was only 1.2 times as fast. After 5 hours the formation of methemoglobin in the alpha crosslinked Hb A is 21.3% compared to 10.8% in beta crosslinked Hb A and 6.4% in Hb A. These results may effect the proposed use of alpha 99 crosslinked hemoglobin as a blood substitute by demonstrating the need for protection from autoxidation during storage.     

Photoaffinity labeling of platelet activating factor binding sites in rabbit platelet membranes

A photoreactive, radioiodinated derivative of platelet activating factor (PAF), 1-O-(4-azido-2-hydroxy-3-iodobenzamido)undecyl-2-O-acetyl-sn- glycero-3-phosphocholine ([125I]AAGP), was synthesized and used as a photoaffinity probe to study the PAF binding sites in rabbit platelet membranes. The nonradioactive analog, IAAGP, induced rabbit platelet aggregation with an EC50 value of 3.2 +/- 1.9 nM as compared to 0.40 +/- 0.25 nM for PAF. Specific binding of [125I]AAGP to rabbit platelet membranes was saturable with a dissociation constant (Kd) of 2.4 +/- 0.7 nM and a receptor density (Bmax) of 1.1 +/- 0.2 pmol/mg protein. Photoaffinity labeling of platelet membranes with [125I]AAGP revealed several 125I-labeled components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A protein species with apparent molecular weight of 52,000 was consistently observed and inhibited significantly by unlabeled PAF at nanomolar concentrations. The labeling was specific since the PAF antagonists, SRI-63,675 and L-652,731, at 1 uM also blocked the appearance of this band; whereas lysoPAF was not effective at the same concentration. These results suggest that the binding sites of PAF receptor in rabbit platelets reside in the polypeptide of Mr = 52,000.     

Fetal and adult sheep adrenal cortical cells contain glucocorticoid receptors

Specific receptors for glucocorticoids were identified in the fetal and adult sheep adrenal cortex by a whole-cell binding assay using [3H]triamcinolone acetonide ([3H]TA) as the radiolabelled ligand. [3H]TA binding sites were saturable and of high affinity, with dissociation constant (Kd) of 2-3nM. Scatchard analysis revealed a single class of binding sites with a binding capacity (Bmax) of 207 and 5 fmol/10(6) cells for d100 fetuses and adults, respectively. By single point analyses at saturating [3H]TA concentration, we found that glucocorticoid receptors (GR) were present in the fetal adrenal cortex as early as d60. Highest concentrations were found at d100-110. GR decreased to d125, then increased to term (approx. d145) before declining again in newborn and adult animals. This demonstration of glucocorticoid receptors in ovine fetal adrenal cortical cells provides a mechanistic basis for the concept that glucocorticoids may act, perhaps in a paracrine or autocrine fashion, to influence adrenocorticotropin (ACTH)-induced activation of fetal adrenal function and the events leading to parturition.