Vitronectin and its fragments purified as serum inhibitors of Staphylococcus aureus gamma-hemolysin and leukocidin, and their specific binding to the hlg2 and the LukS components of the toxins.

Staphylococcal gamma-hemolysin and leukocidin are bi-component cytolysins, consisting of LukF (or Hlg1)/Hlg2 and LukF/LukS, respectively. Here, we purified serum inhibitors of gamma-hemolysin and leukocidin from human plasma. Protein sequencing showed that the purified inhibitors of 62, 57, 50 and 38 kDa were the vitronectin fragments with truncation(s) of the C-terminal or both N- and C-terminal regions. The purified vitronectin fragments specifically bound to the Hlg2 component of gamma-hemolysin and the LukS component of leukocidin to form high-molecular-weight complexes with them, leading to inhibition of the toxin-induced lysis of human erythrocytes and human polymorphonuclear leukocytes, respectively. Intact vitronectin also showed inhibitory activity to the toxins. The ability of gamma-hemolysin and leukocidin to bind vitronectin and its fragments is a novel function of the pore-forming cytolysins.     

Corticosteroidogenesis in the hypertrophic adrenal gland produced by betamethasone 17, 21-dipropionate in the rat fetus

Betamethasone 17, 21-dipropionate (BMDP), a potent glucocorticoid, produces adrenal hypertrophy in the rat fetus. The present study was performed to investigate the possible alterations of corticosteroidogenesis due to endogeneous substrates or exogenous pregnenolone in the incubation of homogenates of fetal hypertrophic adrenals caused by BMDP given to pregnant rats at day 19 of pregnancy.The corticosteroidal products and those levels per mg homogenate in an incubate of the hypertrophic adrenal homogenate did not differ from those of a normal adrenal. No accumulations of abnormal precursors or intermediates were found in the incubates of the hypertrophic adrenals. It is concluded from these findings that no qualitative alterations in the pathway of corticosteroidogenesis occurred in the hypertrophic adrenal glands caused by BMDP in the rat fetus. When the calculation was done per adrenal gland, the content of corticosterone in the incubate of the homogenate of the hypertrophic adrenal was remarkably higher than that found in a normal gland. This finding was compatible with the significant increase of the plasma corticosterone concentration in the fetuses with the adrenal hypertrophy caused by BMDP.     

Incorporation of Serine-3-14C into Sphingolipid by Rat Liver Particulate

Four semi-synthetic and fourteen quassinoids were tested for their antifeedant and insecticidal activity against 3rd instar larvae of the diamondback moth (Plutella xylostella). In this quassinoid series, isobrucein-B was the most potent compound in both assays. Chemical conversion of the methoxy and/or methylenedioxy groups in the A and C rings to hydroxy groups among these quassinoids resulted in decreased activity.     

Digestibility of the hydrogenated derivative of an isomaltooligosaccharide mixture by rats.

The digestibility of the hydrogenated derivative of an isomaltooligosaccharide mixture (IMO-H) was investigated. In an in vitro experiment, the digestibility of IMO-H was examined by models of the digestive system. IMO-H was resistant to two types of alpha-amylase and to artificial gastric juice. Enzymes in the rat small intestinal mucosa hydrolyzed tri-, tetra- and higher saccharide alcohols to disaccharide alcohol, removing successive glucose units from the non-reducing ends of the chains. The hydrolysis ratio for IMO-H was intermediate between the values for maltose and maltitol. In an in vivo study, growing rats were fed on an experimental diet containing IMO-H, maltitol, or hydrogenated palatinose in the range from 5% to 20%. The growth parameters of the rats fed on the test sugar show that the availability of IMO-H was about 1.2 to 1.25 times that of maltitol or hydrogenated palatinose.     

Neoplastic cell transformation by heavy ions

We have studied the induction of morphological transformation by heavy ions. Golden hamster embryo cells were irradiated with 95 MeV 14N ions (530 keV/microns), 22 MeV 4He ions (36 keV/microns), and 22 MeV 4He ions with a 100-microns Al absorber (77 keV/microns) which were generated by a cyclotron at the Institute of Physical and Chemical Research in Japan. Colonies were considered to contain neoplastically transformed cells when the cells were densely stacked and made a crisscross pattern. It was shown that the induction of transformation was much more effective with 14N and 4He ions than with gamma or X rays. The relative biological effectiveness (RBE) relative to 60Co gamma rays was 3.3 for 14N ions, 2.4 for 4He ions, and 3.3 for 4He ions with a 100-microns Al absorber. The relationship between RBE and linear energy transfer was qualitatively similar for both cell death and transformation.     

Analgesic effects of dynorphin-A and morphine in mice

To investigate whether or not dynorphin-A is analgesic, the effect of this peptide was tested in comparison with that of morphine in mice. Dynorphin-A produced a potent analgesic effect in the acetic acid writhing and tail pinch tests, but a weak effect in the tail flick test when given by intracerebroventricular injection. In contrast, morphine caused a potent analgesia in all the tests. Dynorphin-A was more effective when given by intrathecal injection than by intracerebroventricular injection, whereas morphine was equipotent by both injection routes. The results suggest that dynorphin-A is analgesic and that its analgesia may be differentiated from that of morphine.     

On computational efficiency of the hybrid Monte Carlo method applied to the multicanonical ensemble

Abstract

In the present paper, computational efficiency of the hybrid Monte Carlo (HMC) method applied to the multicanonical ensemble is studied; the HMC is an equation of motion guided Monte Carlo method. As in the standard HMC for the canonical ensemble, the multicanonical HMC calculations with high acceptance ratio show better efficiency; about 60% acceptance yields the best performance for the system examined.