Interferon affects intracellular calmodulin levels

Interferon lowers calmodulin levels in two cell lines sensitive to its antiproliferative effect. Further, in synchronized cells, interferon strongly inhibits the increase in calmodulin observed when control cells enter the S phase, and concomitantly inhibits DNA synthesis. Calmodulin has been implicated in the control of cell proliferation and an increase in this protein seems to be necessary for the progression of cells into the S phase of the cell cycle. Therefore, the effect of interferon on calmodulin content might constitute part of the molecular mechanism by which interferon inhibits DNA synthesis.     

A modified method of UDS detection in vitro suitable for screening the DNA-damaging effects of chemicals

The UDS induced in cultured FL cells by exposure to chemicals was measured as hydroxyurea-resistant incorporation of 3H-TdR in the acid-insoluble fraction of the 14C-TdR-prelabelled cells synchronized by the combination of arginine starvation and pretreatment with hydroxyurea. The level of UDS is represented by the ratios of 3H/14C radioactivities which are measures of specific activities of 3H. Two direct-acting alkylating agents, MMS and MNNG, a cross-linking agent, mitomycin C, and 3 procarcinogens, B(a)P, AFB1 and cyclophosphamide elicited UDS in the absence or presence of the liver-metabolizing system. Three chemicals of unknown carcinogenicity were also able to induce UDS in this assay system, i.e., bis-(O,O-diethylphosphinothioyl)-disulphide, 4-chlorophenoxy acetic acid (sodium salt) and caramelized malt sugar. With the exception of 4-chlorophenoxy acetic acid, they were also active in the Ames test.     

天冬酰胺酶及PEG_2-天冬酰胺酶对L-天冬酰胺、谷氨酰胺亲和性的研究

本文报导了天冬酰胺酶及PEG_2-天冬酰胺酶对废物L-天冬酰胺、谷氨酰胺亲和性的研究,结果表明:PEG_2-天冬酰胺酶对谷氨酰胺的亲和性明显强于天冬酰胺酶(Km值分别为7.35×10~(-3)mol/L和7.14×10~(-2)mol/L),对天冬酰胺的亲和性略强于天冬酰胺酶(Km值分别为2.9×10~(-5)mol/L和4.0×10~(-5)mol/L)。天冬酰胺酶和PEG_2-天冬酰胺酶的CD光谱表明:天冬酰胺和谷氨酰胺对天冬酰胺酶和PEG_2-天冬酰胺酶的构象影响较大,但天冬酰胺酶和PEG_2-天冬酰胺酶的构象变化趋势有明显的不同。     

下肢长骨骨重的非对称性

本文测量82副中国成年下股长骨即股骨,胫骨和腓骨的重量,在两侧骨重相差>1％时,则股骨、胫骨和腓骨及其三骨总重均以非对称性为多,均具有非常显著性差异(P<0.001)。除腓骨重具有明显侧别差异外,其余无显著性侧别差异,对腓骨侧差解释为:①腓骨主要机能是肌的附着,而下肢对踢和足趾取物具有明显的侧别差异;②以两侧骨重相差>1％时为非对称性的标准,由于腓骨绝对重量较小,在两侧相差<0.5克时即多属非对称性。     

云南景颇族的体质特征

本文调查了云南景颇族261人（男105人,女156人）。年龄为成年人（男24－60岁,女23－55岁）。主要测量均值与现代中国汉族和云南省各少数民族比较和聚类分析的结果表明,景颇族属黄种人的东亚类型,但也有南亚类型特征表现。体质特征与傣族、哈尼族和彝族接近,与基诺族和布郎族较远。     

钐在小鼠肝脏细胞中的动态观察

It is generally considered that the rare earth compounds are plasma membrane-impermeable, thus affecting the cells only on their surface. Recently, we found that after repeated injections to mice of large dose of samarium trichloride, a soluble compound of rare earth, samarium aggregates appeared in Kupffer cells and hepatocytes of liver. In this study, we aimed at observing the route by which samarium enters the liver cells and the process of the formation of samarium aggregates. Samarium trichloride was given to Swiss mice at one dose of 70 mg/kg intravenously. Thereafter, at different intervals from 15 min to 48 h after the injection, the samarium in liver was traced dynamically by electron microscopy and X ray microanalysis. From 15 min to 2 h both Kupffer cells and hepatocytes endocytosed samarium-containing particles and formed phagosomes, in which the ingested particles were progressively concentrated. Besides, the small phagosomes fused with each other. Phagocytosis was especially active in Kupffer cells. During the 4 h to 24 h many Kupffer cells were degenerated and broken. In hepatocytes the phagosomes gathered mostly around the bile canaliculi. Groups of highly electron-dense particles were found in the lumen of bile canaliculi, implying the excretion of samarium by bile. At the 48 h, the samarium-containing phagosomies were found still in both kinds of cells in the liver.     

Identification of a crotoxin-binding protein in membranes from guinea pig brain by photoaffinity labeling

Crotoxin is a neurotoxic phospholipase A₂ capable of blocking synaptic transmission by inhibiting the release of neurotransmitters. The photoaffinity labeling technique was used to identify the neural membrane molecules involved in the binding of crotoxin. A photoactivatable, radioactive derivative of crotoxin was synthesized by reacting crotoxin withN-hydroxysuccinimidyl-4-azidobenzoate and with Na[¹²⁵I]. Photoirradiation of synaptosomes from guinea pig brains in the presence of the crotoxin derivative resulted in the formation of a major radioactive conjugate of 100,000 daltons as revealed by autoradiography of a sodium dodecyl sulfate-polyacrylamide gel electrophoretic pattern. Pretreatment of the synaptosomes with trypsin,Staphylococcus aureus protease, or papain prevented the formation of this conjugate. The conjugate was not detected when plasma membranes from several nonneural tissues replaced the brain synaptosomes. Unmodified crotoxin inhibited the formation of this adduct with an IC₅₀ of about 10^–8 M. Mojave toxin, caudoxin, notexin,Naja naja PLA, and taipoxin also inhibited adduct formation with different potencies, while -bungarotoxin and pancreatic PLA were ineffective. We concluded that an 85,000-dalton protein is the major component responsible for the binding of crotoxin to synaptosomal membranes.On leave from Department of Biochemistry and Biophysics, University of Hawaii School of Medicine, Honolulu, Hawaii.     

Simultaneous convective and diffusive mass transfers in a hemodialyser

The mass transfer in a hemodialyser in the presence of combined dialysis and ultrafiltration has been calculated by integration of mass fluxes across the boundary layers in blood and dialysate phase taking into account the partial rejection of solute as well as changes in local blood flow and ultrafiltration flux along the membrane. Clearances of creatinin, vitamin B12, and myoglobin have been calculated as a function of blood and ultrafiltrate flow rate and were found to be in good agreement with in vitro measurements. The data suggest the following empirical correlation for the hemodiafiltration clearance.     

云南的金鹬虻属五新种（双翅目：鹬虻科）

本文报道了在云南发现的金鹬虻属五新种,并与已发表种作了必要的比较。