我国优秀划船运动员肱骨X线测量分析

本文对全国优秀划船运动员进行了肱骨X线摄片与测量,同时,将划船运动员与非运动员以及划船运动各专项运动员分别进行了对比。结果表明:划船运动,尤其是划艇专项训练对肱骨的生长发育具有良好的影响。本文资料可作为体育训练及运动员选材的参考。     

Some cellular immune reactions in infants. MIF,E-rosette formation and changes in nucleolar morphology

The cellular immune response (MIF, E-rosette formation and changes in nucleolar morphology of lymphocytes) was followed as related to age and antigenic stimulation. MIF in healthy infants increased from the 2nd to the 12th week of life as compared with the first week, probably due to BCG vaccination. The total and active E-rosette formation did not change during the whole period of investigation. Ring-shaped nucleoli increased gradually from the second week of life. Active nucleoli increased up to the 4th week,i.e. after BCG vaccination and then slowly decreased. Micronucleoli being high in the first week, decreased during 24 weeks of life. After artificial colonization of the intestine the production of MIF was slightly lower in colonized infants than in controls from the 2nd to the 12th week. The other parameters followed were not influenced by colonization.     

Crystal structure of cholestanyl caprylate and binary phase behavior with cholesteryl caprylate

The crystal structure of cholestanyl n-octanoate (caprylate) (C35H62O2) is monoclinic with space group A2 and cell dimensions a = 10.103(7), b = 7.646(7), c = 87.63(7) A, beta = 90.51(6) degrees; Z = 8 [two molecules (A, B) in asymmetric unit], V = 6769 A3, Dc = 1.010 g cm-3. Integrated X-ray intensities for 3798 reflections with I greater than 2 sigma (I) were measured with a rotating anode diffractometer at room temperature. The structure was determined using direct methods. Block diagonal least squares refinement gave R = 0.111. Molecules A and B have almost fully extended conformations, but differ significantly in the rotation about the ester bond and in the C17 chains. The molecular packing in the crystal structure of cholestanyl caprylate consists of stacked bilayers each having d002 = 43.8 A in thickness and within each bilayer, cholestanols pack with cholestanols and caprylate chains pack with caprylate chains. The crystal structure is very similar to that of cholesteryl myristate but is quite different from that of cholesteryl caprylate. The phase equilibria of the cholestanyl caprylate/cholesteryl caprylate binary system have been shown to involve limited mutual solubility of the two components and to have a eutectic point at 73% cholestanyl caprylate. The cholesteric mesophase is monotropic at all compositions except for a narrow range near the eutectic point where it is enantiotropic.     

Isolation, expression, and mutation of a rabbit skeletal muscle cDNA clone for troponin I. The role of the NH2 terminus of fast skeletal muscle troponin I in its biological activity.

A cDNA for rabbit fast skeletal muscle troponin I (TnI) was isolated and sequenced. The clone contains a coding sequence predicting a 182-amino-acid protein with a molecular mass of 21,162 daltons. The translated sequence is different from that reported by Wilkinson and Grand (Wilkinson, J. M., and Grand, R. J. A. (1978) Nature 271, 31-35) in that Arg-153, Asp-154, and Leu-155 must be inserted into their original sequence. Amino acid sequencing of adult rabbit TnI confirmed this result. In order to investigate the role of the NH2 terminus of TnI in its biological activity, we have expressed a recombinant deletion mutant (TnId57), which lacks residues 1-57, in a bacterial expression system. Both wild type TnI (WTnI) and TnId57 inhibited acto-S1-ATPase activity and this inhibition could be fully reversed by troponin C (TnC) in the presence of Ca2+. Additionally both WTnI and TnId57 bound to an actin affinity column. Thus, both inhibitory actin binding and Ca(2+)-dependent neutralization by TnC were retained in TnId57. TnC affinity chromatography was used to compare the binding of TnI and TnId57 to TnC. Using this method, two types of interaction between TnC and TnI were observed: 1) one which is metal independent (or structural) and 2) one dependent on Ca2+ or Mg2+ binding to the Ca(2+)-Mg2+ sites of TnC. The same experiments with TnId57 demonstrated that the type 1 interaction was weakened, and type 2 binding was lost. This method also revealed an interaction between TnC and TnI which is dependent upon Ca2+ binding to the Ca(2+)-specific sites of TnC and which is retained in TnId57. Taken together, these results suggest that the NH2 terminus of TnI may constitute a Ca(2+)-Mg(2+)-dependent interaction site between TnC and TnI and play, in part, a structural role in maintaining the stability of the troponin complex while the COOH terminus of TnI contains a Ca(2+)-specific site-dependent interaction site for TnC as well as the previously demonstrated Ca(2+)-sensitive inhibitory and actin binding activities.     

The solubility of inclusion proteins from Bacillus thuringiensis is dependent upon protoxin composition and is a factor in toxicity to insects.

Bacillus thuringiensis subsp. aizawai HD133 is one of several strains particularly effective against Plodia interpunctella selected for resistance to B. thuringiensis subsp. kurstaki HD1 (Dipel). B. thuringiensis subsp. aizawai HD133 produces inclusions containing three protoxins, CryIA(b), CryIC, and CryID, and the CryIC protoxin has been shown to be active on resistant P. interpunctella as well as on Spodoptera larvae. The CryIA(b) protoxin is very similar to the major one in B. thuringiensis subsp. kurstaki HD1, and as expected, this protoxin was inactive on resistant P. interpunctella. A derivative of B. thuringiensis subsp. aizawai HD133 which had been cured of a 68-kb plasmid containing the cryIA(b) gene produced inclusions comprising only the CryIC and CryID protoxins. Surprisingly, these inclusions were much less toxic for resistant P. interpunctella and two other Lepidoptera than those produced by the parental strain, whereas the soluble protoxins from these strains were equally effective. In contrast, inclusions from the two strains were about as active as soluble protoxins for Spodoptera frugiperda larvae, so toxicity differences between inclusions may be due to the solubilizing conditions within particular larval guts. Consistent with this hypothesis, it was found that a higher pH was required to solubilize protoxins from inclusions from the plasmid-cured strain than from B. thuringiensis subsp. aizawai HD133, a difference which is probably attributable to the absence of the CryIA(b) protoxin in the former. The interactions of structurally related protoxins within an inclusion are probably important for solubility and are thus another factor in the effectiveness of B. thuringiensis isolates for particular insect larvae.     

In vivo inhibition of megakaryocyte and platelet production by platelet factor 4 in mice.

The in vivo effect of human platelet factor 4 (PF4) on murine megakaryocytopoiesis and thrombopoiesis was studied. Administration of PF4 induced a dose-dependent decrease in the numbers of megakaryocytes and their progenitor cells (CFU-MK), continuing for 1 week after the injection. However, the size of megakaryocytes and their colonies was not changed following PF4 injection. Platelet levels were significantly decreased at days 3-4. The number of CFU-GM was decreased at days 1-2. White blood cells and hemoglobin were unaffected by PF4. These data indicate that PF4 inhibits megakaryocyte and platelet production in vivo by acting on the early stage of megakaryocyte development.     

Sugar transport by the bacterial phosphotransferase system. Fluorescence studies of subunit interactions of enzyme I

Enzyme I of the bacterial phosphoenolpyruvate:glycose phosphotransferase system (PTS) exhibits a temperature-dependent monomer/dimer equilibrium. The accompanying paper (Han, M. K., Roseman, S., and Brand, L. (1990) J. Biol. Chem. 265, 1985-1995) shows that the C-terminal -SH residue (Cys-575) can be modified specifically with fluorescent probes such as pyrene maleimide. The derivative retains full enzyme activity, and is capable of forming dimers at room temperature. In the present studies, Enzyme I labeled in this way is found to exhibit a temperature-, concentration-, and pH-dependent monomer/dimer association. The kinetics of dimer formation of Enzyme I is measured in the following way. A derivatized Enzyme I sample is prepared with a pyrene moiety irreversibly attached to the C-terminal -SH residue and 5,5'-dithiobis-2-nitrobenzoic acid reversibly attached to the other 3 -SH residues. This modified enzyme does not form dimers at room temperature. Addition of dithiothreitol results in total release of the thionitrobenzoate anion within 2 min. After the three -SH groups are unblocked, steady-state and nanosecond time-resolved emission anisotropy measurements indicate the dimer is formed over a period of 30 min. In a similar experiment, little dimer formation is observed at 3 degrees C, at temperature at which the native enzyme also does not form dimers. Tryptophan fluorescence is also examined during the release of the thionitrobenzoate. After the completion of thionitrobenzoate release, additional slow steady-state tryptophan fluorescence changes are observed. These results suggest that dimer formation may be preceded by a conformational change following thionitrobenzoate release.