Multiple forms of human kidney mutarotase

Summary 4 forms of mutarotase from human kidney were demonstrated by DEAE-cellulose column chromatography. A major form of them was purified to homogeneity.     

Influence of pinealectomy on serum estrogen and progesterone levels in blind-anosmic female rats

Summary Previous studies show that the suppression of gonadal function in blind-anosmic rats is dependent on the pineal gland. The present results demonstrate that in young female rats both the pineal gland and dual sensory deprivation have additional independent antigonaldal effects.This work was partially supported by state institutional funds and by NSF grant No. PCM 74-06276-276-A02. The radioimmunoassays of the steroids were carried out with the aid of the Radioimmunoassay Core which is supported by USPHS grant No. 1T30 HD-10202. We also thank Constance Stahl for typing assistance.     

Geranylgeranylacetone protects human monocytes from mitochondrial membrane depolarization independently of Hsp70 expression

The anti-ulcer drug geranylgeranylacetone (GGA) has been shown to induce the expression of heat shock proteins (HSPs), in particular of Hsp70, in gastric and small intestine cells. In this study, we investigated whether GGA was able to induce Hsp70 in another cell type, human monocytes, which represent a well-established model of Hsp70 expression under oxidative stress. In these cells, GGA had no significant effect either on basal or tobacco smoke-induced Hsp70 expression. We further investigated the effects of GGA on mitochondria, a key organelle of oxidant-mediated cell injury and a putative target for GGA-mediated protection. GGA significantly increased basal mitochondrial membrane polarization and inhibited the decrease in mitochondrial membrane potential of human monocytes exposed to distinct sources of clinically relevant oxidants such as tobacco smoke and y-irradiation. Our results indicate that mitochondria are targets for GGA-mediated protection against oxidative stress in human monocytes, independently of Hsp70.     

N-acetylglucosaminyltransferase V modifies the signaling pathway of epidermal growth factor receptor

Transfection of sense cDNA of N-acetylglucosamyltransferase V (GnTV-S) into human H7721 hepatocarcinoma cells resulted in an increase in the N-acetylglucosamine1,6mannose1,3- branch (GnT-V product) on the N-glycans of epidermal growth factor (EGF) receptor (EGFR), and promotion of its EGF binding and tyrosine autophosphorylation, but showed little effect on the expression of EGFR protein. The phosphorylation at T308, S473 and tyrosine residue(s) and the activity of protein kinase B (Akt/PKB) as well as the phosphorylation of p42/44 mitogen-activated protein kinase (MAPK) and MAPK kinase (MEK) before and after EGF stimulation were concomitantly increased. Conversely, in the antisense GnT-V (GnTV-AS)-transfected H7721 cells, all the results were the reverse of those with GnTV-S-transfected cells. After the cells were treated with 1-deoxymannojirimycin, an inhibitor of N-glycan processing at high mannose, or antibody against the extracellular glycan domain of EGFR, the differences in PKB activity, p42/44 MAPK and MEK phosphorylation among GnTV-S-, GnTV-AS- and mock-transfected cells were significantly attenuated. These findings indicate that the altered expression of GnT-V will change the glycan structure and function of EGFR, which may modify downstream signal transduction.Received 24 March 2004; received after revision 1 May 2004; accepted 25 May 2004     

Intraventricular administration of isoproterenol inhibits both heat production and heat loss mechanisms in rats

Summary At an ambient temperature (T_a) of 8°C, intraventricular administration of isoproterenol inhibited metabolic heat production and led to hypothermia in rats. In contrast, at a T_a of 22°C and of 30°C, isoproterenol decreased cutaneous circulation and led to hyperthermia. The data indicate that isoproterenol inhibits both heat production and heat loss mechanisms in rats.This work was supported by a grant from the National Science Council of the Republic of China. The authors are grateful to Dr C.Y. Chai for pertinent advice.     

Reversible depression of spontaneous brain electrical activity induced by actinomycin D and 7-aminoactinomycin D in rats

Summary Various types of actinomycin (C, D, S₂, I and V) and 7-amino-analogue of actinomycin D were injected into the right lateral ventricle of the brain through a chronically implanted cannula. In rats but not in mice actinomycin D, actinomycin S₂ and 7-aminoactinomycin D caused depression of EEG, while cardiac and respiratory activity were maintained. This effect of the EEG was reversible and a normal EEG pattern reappeared at least 3 h after administration.     

Contraction of the large conductance coronary artery produced by acetylcholine in the mini pig

Summary In the mini pig, acetylcholine reduced the coronary blood flow and constricted the large coronary artery. These effects were abolished by atropine, but not by phentolamine, suggesting that cholinergic mechanisms may be involved in coronary artery vasoconstriction.     

Photoresponses in colorlessParamecium

Summary Two species of colorlessParamecium, P. caudatum andP. tetraurelia, were suspended in a saline solution. They accumulated in the shaded region when they were introduced into a half-shaded glass tube and illuminated. 520 nm light was most effective in stimulating the accumulation.The work was supported by grants from Mitsubishi Foundation and from Ministry of Education of Japan to Y.N. (144006, 411802, 411808, 510902, 511201).The authors would like to thank Drs T. Ikawa, F. Fukui, K. Kobayashi and S. Ishizaka for many suggestions and helpful discussions. To whom reprint requests should be addressed.