Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of previous studies have indirectly (electron paramagnetic resonance, nitrite/nitrate, ribonuclease protection assay for inducible nitric oxide synthase (iNOS) mRNA, l-citrulline assay) demonstrated the production of nitrogen monoxide (NO) during early cardiac allograft rejection. This study reports the first direct, quantitative measurement using an electrochemical method of NO produced from rejecting allograft tissue studied in vitro. A rat heterotopic abdominal transplant preparation was utilized. Day 7 isograft (ACI to ACI) or allograft (Lewis to ACI) transplanted hearts were atraumatically harvested and suspended at 4 degrees C in Ringers-Hepes solution. An electrochemical system highly sensitive and specific for NO consisting of a Nafion-coated platinum disk electrode (lower limit, 50 nM NO) coupled to an analysis system measured ongoing oxidation of NO. Measurements were carried out after inserting the electrode in the tissue block and warming the block to 25 degrees C. Additional measurements were also made after incubation of tissue with aminoguanidine (AG), a relatively selective iNOS inhibitor. Direct measurements (mean +/- SEM) from allograft tissue indicated a fourfold increase in NO as compared with isografts (13.41 +/- 4.40 microM NO vs. 3.43 +/- 2.04 microM NO). Incubation of allograft tissue with AG reduced NO levels to isograft levels (13.41 +/- 4.40 microM NO vs. 5.94 +/- 3.14 microM NO); AG had no effect on measured isograft NO levels. Direct, quantitative measurement of NO from tissue is feasible and reproducible, and discrimination between different levels of NO production can be made. These results confirm the imputed results from the previous studies using this experimental model. This technology promises to be a valuable tool for evaluating specific modulators of NO production studied under a variety of physiologic and pathophysiologic conditions.
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PMID:In situ measurement of nitric oxide production in cardiac isografts and rejecting allografts by an electrochemical method. 1173 Mar 63

To understand the role of estrogen in testicular and epididymal function of rhesus monkeys, we measured steroids in the spermatic and peripheral venus circulation and aromatase activity and its mRNA in testis and epididymis. Testosterone, estradiol-17beta, and estrone, but not androstenedione, were elevated in the spermatic vein serum compared to the peripheral circulation. Aromatase activity in testis and in caput epididymis (259+/-16 [SEM] vs 274+/-47 fmol of 3H2O/mg of protein/h [n = 10], respectively) was significantly higher (p < 0.01) than in corpus and cauda (124+/-28 and 113+/-33 fmol of 3H2O/mg of protein/h [n = 10], respectively). In the ribonuclease protection assay, two P450arom mRNA transcripts were identified in testis and epididymis. One corresponded with the aromatase full-length transcript and the other was a truncated isoform. The latter was significantly more abundant than the former (p < 0.01). Our results demonstrate that the monkey testis and, to a lesser extent, the epididymis can aromatize androgens. However, in the epididymis, like in some areas of the brain, there was a discrepancy between the aromatase activity and the mRNA. The fact that P450arom mRNA and aromatase activity do not correlate in the epididymis may indicate that aromatase activity is not strictly regulated at the level of RNA expression and that other mechanisms for this regulation should be considered.
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PMID:Cytochrome P450 aromatase in testis and epididymis of male rhesus monkeys. 1182 22

In the present study, it was hypothesized that the adrenocorticotrophin hormone receptor (ACTH-R) would be up-regulated in the adrenal gland of the sheep fetus following infusion of physiological amounts of ACTH, as shown for adrenal cortical cells in culture. In chronically catheterized sheep, an intravenous infusion of ACTH(1-24) was given to 6 fetuses for 24 h at a rate of 0.5 microg h(-1), starting on Day 126 or 127 of gestation (term approximately 147 days). Four control fetuses received an infusion of vehicle (saline). Total RNA was extracted from the fetal adrenal glands by the guanidinium thiocyanate method. Expression of specific mRNAs was determined by ribonuclease protection assay using cRNA probes directed against: ACTH-R; the steroid enzymes side-chain cleavage (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17apha-hydroxylase (P450c17) and 21beta-hydroxylase (P450c21); and beta-actin. Ratios of mRNA expression to beta-actin mRNA expression (arbitrary units) were calculated to correct for differences in RNA quality between samples. The concentration (mean +/- SEM) of immunoreactive cortisol in fetal plasma was greater after ACTH infusion than after vehicle infusion (47 +/- 3 v. 13 +/- 2 ng mL(-1) respectively; P<0.001). Adrenal expression of P450scc and P450c21 mRNA increased after ACTH infusion (P<0.05), whereas expression of P450c17 and 3beta-HSD mRNA was unchanged. There was no difference in ACTH-R mRNA expression between ACTH- and vehicle-infused fetuses (254 +/- 48 v. 305 +/- 76 arbitrary units respectively). It was concluded that ACTH is able to increase plasma cortisol concentrations in the sheep fetus by up-regulating cortisol synthesis in the adrenal gland, but that in vivo this does not require up-regulation of ACTH-R mRNA.
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PMID:Adrenocorticotrophic hormone (ACTH) stimulation of sheep fetal adrenal cortex can occur without increased expression of ACTH receptor (ACTH-R) mRNA. 1205 14

Bovine seminal-ribonuclease (BS-RNase) is a member of the 'ribonucleases with special biological actions' family since it possesses specific anti-tumour, anti-spermatogenic and embryotoxic activities and exerts an immunosuppressive effect on T lymphocytes. In previous studies it was demonstrated that BS-RNase induced apoptosis in proliferating, malignant and normal cells and that telomerase activity loss also caused apoptotic death in neoplastic cells. Since an obvious relationship between cell proliferation and telomerase activity exists, the aim of this work was to study if the pro-apoptotic cytotoxic action exerted by BS-RNase on proliferating malignant cells (HT29) and proliferating normal cells (PHA-stimulated lymphocytes) could be linked to a possible BS-RNase effect on telomerase activity. In BS-RNase-treated HT29 cells (Na-butyrate-differentiated or not) and human lymphocytes (proliferating or not), we investigated cell vitality (MTT method) and morphology (SEM), BS-RNase localization (immunofluorescence), telomerase activity (TRAP-ELISA method), hTR mRNA expression (RT-PCR), and hTERT levels (western blot). While no BS-RNase effect was detectable on not proliferating cells, a clear relationship was noticed between the diminished number of vital elements of both proliferating cell populations after treatment (48 h and 72 h for HT29 and PHA-stimulated lymphocytes, respectively) with 50 microg/ml BS-RNase and the decrease of their telomerase activity. At the same time, we found that hTR levels, the RNA subunit of telomerase, in proliferation-inhibited BS-RNase-treated cells were diminished. Moreover, by immunofluorescence technique, we detected BS-RNase in the HT29 cell nucleolus after 3-h treatment. Therefore, as hTR has been recently proven to co-fractionate with nucleoli, we hypothesize that a BS-RNase direct action on the telomerase hTR subunit could be a possible mechanism of action by which BS-RNase exerts its pro-apoptotic effects only on proliferating cells.
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PMID:Bovine seminal ribonuclease is cytotoxic for both malignant and normal telomerase-positive cells. 1614 25


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