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The yeast Saccharomyces cerevisiae mRNA capping enzyme is composed of two subunits of alpha (52 kDa, mRNA guanylyltransferase) and beta (80 kDa, RNA 5'-triphosphatase). We have isolated the alpha subunit gene (CEG1) by immunological screening. In this report, with the aid of partial amino acid sequences of purified yeast capping enzyme, we isolated the gene, designated CET1, encoding the S. cerevisiae capping enzyme beta subunit. Amino acid sequence analysis revealed that the gene encodes for 549 amino acids with a calculated M(r) of 61,800 which is unexpectedly smaller than the size estimated by SDS-PAGE. Gene disruption experiment showed that CET1 is essential for yeast cell growth. The purified recombinant CET1 gene product, Cet1, exhibited an RNA 5'-triphosphatase activity which specifically removed the gamma-phosphate from the triphosphate-terminated RNA substrate, but not from nucleoside triphosphates, confirming the identity of the gene. Interaction between the Cet1 and the Ceg1 was also studied by the West-Western procedure using recombinant Ceg1-[32P]GMP as probe. 相似文献
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KS Tsai WC Cheng TV Sanchez CK Chen PU Chieng RS Yang 《Canadian Metallurgical Quarterly》1997,20(4):365-369
Whether an association exists between cystopathy and progression of diabetic nephropathy has never been clarified. The aim of the present study was to measure the degree of cystopathy in relation to the rate of progression of diabetic nephropathy. To that end, 17 insulin-dependent diabetic patients with diabetic nephropathy but without voiding symptoms were investigated urodynamically. The median age of the patients was 45 years (range 27-67 years), diabetes duration 23 years (range 14-44 years) and the serum creatinine level was 162 mumol/L (median, range 65-449 mumol/L) at the time of the study. The progression rate of diabetic nephropathy was analysed retrospectively by measuring changes in yearly mean values of Log10 serum creatinine for a period of 13 years (3-15 years) before the investigation. The progression rate was 0.028 mumol/L/year (median). Patients with a progression rate above and below the median rate were considered to be rapid (n = 8) and slow (n = 9) progressors, respectively. More women than men had a rapid progression rate of nephropathy. Rapid progressors were found to have smaller volume or residual urine (90 vs 165 ml; p < 0.05), larger volume voided (440 vs 270 ml; p < 0.05), lower opening pressure (18 vs 48 cm H2O; p < 0.05) and lower pressure at maximum flow (37 vs 64 cm H2O; p < 0.05) compared to slow progressors. However, these variables were not related to the progression rate of nephropathy (MANOVA). Furthermore, these results should be interpreted with caution because of the natural gender differences in pressure conditions. In conclusion, rapid progression of diabetic nephropathy does not seem to be associated with dysfunction of the urinary bladder measured with cystometry and pressure flow. 相似文献
136.
PURPOSE: To examine second messenger pathways involved in neurokinin induced bladder contractions. MATERIALS AND METHODS: Neurokinin induced changes in inositol phosphate production and in adenylyl cyclase activity are measured in the guinea pig bladder. RESULTS: Substance P, substance P methyl ester, neurokinin A, and neurokinin B each increase [3H]-inositol phosphate production in the guinea pig bladder. Substance P (10(-6) M) increases [3H]-inositol trisphosphate levels within 30 sec. Substance P and neurokinin A have an additive effect on inositol phosphate production, however substance P (10(-5) M) or neurokinin A (10(-5) M) induced inositol phosphate production is less than that induced by carbachol (10(-5) M). Neurokinin B and to a lesser extent neurokinin A inhibit forskolin-activated adenylyl cyclase activity. CONCLUSIONS: These data are compatible with neurokinin-induced inositol phosphate production being coupled to increases in contractile force of the guinea pig urinary bladder, however more than one second messenger pathway may be involved. 相似文献
137.
The kinetics of efflux of calcium mobilized from intracellular stores following activation of human neutrophils with the synthetic chemotactic tripeptide, fMLP (1 microM), as well as that of the subsequent store-operated influx of this cation, has been measured by radiometric procedures using 45Ca. These procedures enabled distinction between net efflux and influx of 45Ca. Preincubation of neutrophils in medium containing 45Ca as the sole source of Ca2+, followed by activation with fMLP, resulted in a rapid efflux of the cation, which coincided with its release from intracellular stores. Efflux terminated at approximately 30 s after addition of fMLP to neutrophils and resulted in the loss of 42 +/- 3% (P < 0.005) of cell-associated 45Ca. Net influx of 45Ca, which was insensitive to the voltage-dependent Ca2+ channel blockading agent, verapamil (20 microM), could only be detected at 30-60 s after the addition of fMLP to neutrophils, and proceeded for about 5 min, resulting in intracellular concentrations of Ca2+ which were 27 +/- 3% (P<0.05) higher than preactivation levels. These results demonstrate that the efflux of cytoplasmic Ca2+ mobilized from intracellular stores during activation of neutrophils by fMLP, and the subsequent influx of extracellular Ca2+ to replete these stores, are chronologically distinct events in fMLP-activated neutrophils. 相似文献
138.
TV Gurvits ME Shenton H Hokama H Ohta NB Lasko MW Gilbertson SP Orr R Kikinis FA Jolesz RW McCarley RK Pitman 《Canadian Metallurgical Quarterly》1996,40(11):1091-1099
This study used quantitative volumetric magnetic resonance imaging techniques to explore the neuroanatomic correlates of chronic, combat-related posttraumatic stress disorder (PTSD) in seven Vietnam veterans with PTSD compared with seven nonPTSD combat veterans and eight normal nonveterans. Both left and right hippocampi were significantly smaller in the PTSD subjects compared to the Combat Control and Normal subjects, even after adjusting for age, whole brain volume, and lifetime alcohol consumption. There were no statistically significant group differences in intracranial cavity, whole brain, ventricles, ventricle:brain ratio, or amygdala. Subarachnoidal cerebrospinal fluid was increased in both veteran groups. Our finding of decreased hippocampal volume in PTSD subjects is consistent with results of other investigations which utilized only trauma-unexposed control groups. Hippocampal volume was directly correlated with combat exposure, which suggests that traumatic stress may damage the hippocampus. Alternatively, smaller hippocampi volume may be a pre-existing risk factor for combat exposure and/or the development of PTSD upon combat exposure. 相似文献
139.
VM Mikha?lov VN Reushkin GD Reushkina TV Sebekina TM Smirnova 《Canadian Metallurgical Quarterly》1995,29(6):26-32
With the use of dispersion analysis the variation of indices of central and peripheral hemodynamics in healthy volunteers stayed from 1 to 7 days under conditions of "dry" immersion (DI) was studied. Nine persons were investigated at rest, 5 individuals during orthostatic tests before and after dry immersion sessions. The central hemodynamic indices were calculated, the arterial pressure (AD) was measured by Korotkoff's method, indices of rheoencephalographic and rheoplethysmographic indices of lower leg were found. The significant differences of mean values of measured parameters before and after DI at rest were not revealed. Two-factor dispersion analysis of the orthostatic test data revealed the high levels of significance of influencing immersion and personality factors as well as their interaction on the variation of most indices. For excluding an individual uniformity there has been done an analysis of dynamics of indices according to their relative values which allowed one to isolate qualitative peculiarities of changes and distinctions between persons with different orthostatic tolerance even before orthostatic testing. 相似文献
140.
G Seyoum MC Robertson TV Persaud JA Paterson RP Shiu 《Canadian Metallurgical Quarterly》1999,160(2):231-237
Rat placental lactogen-I (rPL-I), the first prolactin-like hormone expressed in the placenta during pregnancy in the rat, is known to influence maternal functions. In the present study, we have investigated the effects of rPL-I on the growth and development of cultured whole rat embryos. Rat embryos, with or without ectoplacental cone (EPC) attached, were explanted at day 9 of gestation. After 48 h of culture, the embryos, enclosed by the yolk sacs, were assessed by the presence of visible heart contractions ('heart beats'), crown-rump length (CRL) and yolk sac diameter (YSD). When intact embryos with EPC were cultured, the concentrations of rPL-I and rPL-II (products of EPC) in the medium were 850+/-841 and 92+/-181 ng/ml respectively (means+/-s.e.m.). In embryo cultures with the EPC removed, rPL-I levels decreased to=10 ng/ml, and only 70% of the embryos were viable, with visible heart beats. In the viable embryos, both CRL and embryonic DNA synthesis were reduced compared with controls, and the addition of rPL-I (1 microg/ml) did not prevent this reduction. YSD and yolk sac DNA synthesis were also reduced compared with control embryos, and the addition of rPL-I significantly prevented this decrease by 45%. In embryos cultured without EPC in the presence of neutralizing rabbit anti-rat prolactin serum (anti-rPRL), embryonic and yolk sac DNA synthesis were reduced by 35% compared with embryos exposed to normal rabbit serum. Addition of rPL-I significantly increased (P<0.05) embryonic and yolk sac growth. Thus the effects of rPL-I on embryo growth could only be seen in the absence of prolactin. The addition of human prolactin in the presence of anti-rPRL also resulted in significant increases (P<0.05) in embryonic DNA synthesis and CRL. These results suggest that rPL-I may substitute for prolactin to influence the growth of the rat embryo. 相似文献