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At least 1,351 records · Page 75Linked to original sources
PubMed2002

Messenger ribonucleic acid levels of interleukin-1 beta, interleukin-6 and interleukin-8 in the lower uterine segment increased significantly at final cervical dilatation during term parturition, while those of tumor necrosis factor alpha remained unchanged.

OBJECTIVE: To investigate the content of tumor necrosis factor alpha, interleukin-1 beta, interleukin-6 and interleukin-8 messenger ribonucleic acid (mRNA) in the lower uterine segment during term parturition. STUDY DESIGN: mRNA extracts from the lower uterine segment obtained from 53 women undergoing non-elective caesarean section at term were analyzed by semi-quantitative reverse transcriptase polymerase chain reaction. The patients were grouped according to cervical dilatation (less than 2 cm, n=18; 2 to less than 4 cm, n=13; 4-6 cm, n=7; more than 6 cm, n=15) at the time of caesarean section. RESULTS: Interleukin-1 beta and interleukin-8 mRNA-contents at more than 6 cm cervical dilation were significantly higher than at less than 2 cm. The levels of interleukin-6 were already significantly increased in the 4-6 cm group, while the tumor necrosis factor alpha ribonucleic acid content did not change during parturition. CONCLUSION: The process of cervical dilatation during parturition at term is associated with an increased expression of interleukin-1 beta, interleukin-6 and interleukin-8 mRNA in the lower uterine segment. These findings support the theory that the activation of the inflammatory network plays an important role in the progress of cervical dilatation.

Cervix Uteri↗
PubMed1975

Kinetics of the onset of catabolite repression in Escherichia coli as determined by lac messenger ribonucleic acid initiations and intracellular cyclic adenosine 3',5'-monophosphate levels.

The rates of synthesis of beta-galactosidase (EC 3.2.1.23) and the intracellular levels of cyclic 3',5'-adenosine monophosphate (cAMP) soon after the addition of glucose or glycerol to exponentially growing cultures of Escherichia coli have been determined. Within 10 s of its addition, glucose, but not glycerol, lowered the apparent initiation frequency of lac messenger ribonucleic acid. The glucose-generated reduction in initiations is identified as catabolite repression by its reversibility with cAMP. The intracellular cAMP levels respond virtually identically to glucose and glycerol additions. Thus, no correlation was observed between the rate of messenger ribonucleic acid initiation and the level of cAMP.

Cyclic AMP↗
PubMed1997

Measurement of human growth hormone receptor messenger ribonucleic acid by a quantitative polymerase chain reaction-based assay: demonstration of reduced expression after elective surgery.

Studies of GH receptor (GHR) gene expression in human tissues have been hampered by the limited amount of tissue available for analysis and the low sensitivity of conventional methods. We have developed a quantitative reverse transcriptase-PCR assay for measurement of GHR messenger ribonucleic acid levels in small human tissue biopsies. To compensate for sample to sample variation, an internal RNA standard, which differs from the wild-type GHR transcript by only a few nucleotides, was reverse transcribed and amplified together with the GHR transcripts. PCR was carried out using one biotinylated primer to permit the purification of single stranded PCR products on streptavidin-coated microtiter plates. The ratio between the wild-type and mutated transcripts was determined by two separate minisequence reactions in which a primer, annealed immediately 3' of a variable nucleotide, was extended by a single 3H-labeled nucleotide, complementary to either the wild-type or mutated sequence. The assay range was 0.125-8 x 10(5) transcripts/sample, the mean intraassay coefficient of variation was 8.7%, and the lower limit of detection was 0.125 x 10(5) transcripts/sample. GHR messenger ribonucleic acid levels were detectable in small amounts (10-100 ng) of total RNA extracted from adipose tissue, skeletal muscle, and liver. The GHR gene expression in liver was approximately 10-fold higher than that in skeletal muscle, whereas intermediate levels were found in adipose tissue. In nine patients undergoing elective abdominal surgery, GHR gene expression in skeletal muscle was reduced on day 3 after surgery compared to the baseline level. The decrease in GHR gene expression was accompanied by a decrease in skeletal muscle glutamine. This suggests that the postoperative protein catabolism may be caused at least partly by acquired GH insensitivity due to reduced expression of the GHR gene.

Abdomen↗
PubMed1976

Regulation of acetylcholinesterase in chick muscle cultures after treatment with diisopropylphosphorofluoridate: ribonucleic acid and protein synthesis.

Previous studies have established that short treatments with diisoprophylphosphorofluoridate of chick embryo muscle cultures irreversibly inhibit the enzyme acetylcholinesterase and that the enzyme's levels in the cells rapidly recover due to synthesis of new protein. In addition, it has been shown that acetylcholine, acetyl-beta-methylcholine and choline increase the acetylcholinesterase content of the cultures. In the experiments presented here, actinomycin D and cycloheximide were used to study the relationships between the synthesis of ribonucleic acid and of protein, the recovery of acetylcholinesterase levels after diisopropylphosphorofluoridate treatment and the increase of acetylcholinesterase levels evoked by choline and its esters. Both recovery of acetylcholinesterase and the increase in its activity with acetyl-beta-methylcholine occurred in the absence of ribonucleic acid synthesis but required protein synthesis. The results suggest that transcription of desoxyribonucleic acid and a change in the degradation rate of acetylcholinesterase are not involved. An additional finding was that the level of newly synthesized acetylcholinesterase activity continued to increase for a short period of time after synthesis of protein had ceased, as if some previously synthesized protein was being transformed into active enzyme.

Acetylcholinesterase↗
PubMed1976

Altered nutritional requirements associated with mutations affecting the structures of ribonucleic acid polymerase in Lactobacillus casei.

Rifampin-resistant mutants were isolated from Lactobacillus casei S1 and examined for possible simultaneous alteration in nutritional properties. Among the 36 mutants obtained either spontaneously or after mutagenesis with 2-aminopurine, 22 were found to be altered with respect to the specific growth requirements. The majority (20 of 22) of the latter mutants were shown to require L-glutamine in addition to the nutrients required by the parental strain for maximal growth, whereas the remaining mutants had apparently lost the requirement for L-aspartate. Further studies with one of the glutamine-requiring mutants revealed that the rifampin resistance of this strain is due to the resistance of ribonucleic acid polymerase itself and that a single mutation is responsible for both rifampin resistance and the glutamine requirement. These results strongly indicate that a structural alteration of the ribonucleic acid polymerase caused by the rifampin resistance mutation somehow affected glutamine metabolism, possibly through change in selective transcription of the genes involved.

2-Aminopurine↗
PubMed1994

Messenger ribonucleic acid expression of platelet-derived growth factor subunits and receptors in pituitary adenomas.

Little is known about the expression of growth factors and their receptors in pituitary tumors or the relationship of growth factors to pituitary neoplasia. Platelet-derived growth factor (PDGF) is a potent mitogen that has been postulated to stimulate tumor growth through autocrine and/or paracrine loops in a number of human tumors. In the present study we demonstrate messenger ribonucleic acid expression of the PDGF subunits and receptors in a variety of human pituitary adenomas and in a normal human anterior pituitary gland. Northern blot analysis performed on 34 pituitary adenomas showed that all tumors expressed the PDGF-A and PDGF-B subunits, the majority (94%) expressed the PDGF-beta receptor, and a subset (44%) expressed the PDGF-alpha receptor. The normal anterior pituitary studied expressed all of the PDGF subunits and receptor subunits. Clinically, there was no correlation between expression of the PDGF subunits or receptors and tumor size or with invasion into adjacent structures (cavernous sinus, sphenoid sinus, or clivus). A higher proportion of the endocrinologically active adenomas expressed the PDGF-alpha receptor (5 of 8) compared to the endocrine inactive tumors (10 of 26). The function of PDGF in the pituitary is currently not known. The finding that PDGF subunit and receptor messenger ribonucleic acids are coexpressed in pituitary adenomas and normal anterior pituitary suggests that autocrine and/or paracrine loops involving PDGF may exist in pituitary adenomas and normal anterior pituitary.

Adenoma↗
PubMed2001

A developmental increase in the expression of messenger ribonucleic acid encoding a second form of gonadotropin-releasing hormone in the rhesus macaque hypothalamus.

GnRH-I is thought to represent the primary neuroendocrine link between the brain and the reproductive axis. Recently, however, a second molecular form of this decapeptide (GnRH-II) was found to be highly expressed in the brains of humans and nonhuman primates. In this study, in situ hybridization was used to examine the regional expression of GnRH-II messenger ribonucleic acid in the hypothalamus of immature (0.6 yr) and adult (10-15 yr) male and female rhesus macaques (Macaca mulatta). Overall, no sex-related differences were observed. In all of the animals (n = 3 animals/group), intense hybridization of a monkey GnRH-II riboprobe was evident in the paraventricular nucleus and supraoptic nucleus and to a lesser extent in the suprachiasmatic nucleus, but no age- or sex-related differences were apparent. Intense hybridization of the riboprobe also occurred in the mediobasal hypothalamus, and this was markedly greater in the adults than in the immature animals. These data show that the expression of GnRH-II messenger ribonucleic acid increases developmentally in a key neuroendocrine center of the brain. Moreover, because GnRH-II can stimulate LH release in vivo, it is plausible that changes in its gene expression represent an important component of the mechanism by which the hypothalamus controls reproductive function.

Animals↗
PubMed1999

Myometrial nitric oxide synthase messenger ribonucleic acid expression does not change throughout gestation or with the onset of labor.

OBJECTIVE: The purposes of this study were to examine expression of nitric oxide synthase isoforms in human myometrium and to determine any changes in expression with gestational age and with the onset of labor at term. STUDY DESIGN: Myometrial samples were collected from patients undergoing cesarean delivery at term before and after the onset of labor (n = 17) and throughout gestation (n = 13). Expressions of inducible, calcium-independent nitric oxide synthase and constitutive, calcium-dependent endothelial nitric oxide synthase were determined by semiquantitative reverse transcriptase-polymerase chain reaction. RESULTS: Messenger ribonucleic acid for inducible, calcium-independent nitric oxide synthase and constitutive, calcium-dependent endothelial nitric oxide synthase is expressed in human myometrium at term and throughout the second and third trimesters. Levels of messenger ribonucleic acid for both inducible, calcium-independent nitric oxide synthase and constitutive, calcium-dependent endothelial nitric oxide synthase do not change with either gestational age or the onset of labor. CONCLUSION: Changes in myometrial nitric oxide synthase expression and thus of levels of endogenous nitric oxide are unlikely to be directly involved in myometrial quiescence or the onset of human parturition.

Calcium↗
PubMed1996

Genomic structure of a Y-specific ribonucleic acid binding motif-containing gene: a putative candidate for a subset of male infertility.

The genetic basis of infertility remains unclear in a majority of infertile men. Deletion mapping studies suggest that genes on the long arm of the Y-chromosome (Yq) may be important in the spermatogenic process and may play a pathogenetic role in a subset of infertile men. Complementary DNA sequences of two Y-specific genes that contain ribonucleic acid binding motifs and, therefore, referred to as RBM genes (previously named YRRM) were published recently. To develop a PCR-single strand conformation polymorphism strategy for detection of point mutations in the RBM gene(s) in infertile men, we determined the genomic structure and flanking sequences at the intron-exon junctions. Two separate strategies were used in parallel to isolate the genomic fragment bearing the RBM gene. The first strategy employed screening of a P1 genomic library using PCR primers corresponding to the sequences in the 5'- and 3'-ends of the published RBM-1 complementary DNA sequence. The second strategy used subcloning of the YAC clone 925D10 (that contained the RBM gene described here) into cosmids. The P1 and cosmid clones were further restriction mapped and subcloned for DNA sequencing. Because the sequences contained in the P1 and cosmid clones were identical, the sequence information was pooled. A 15-kilobase genomic segment includes the entire RBM gene. The genomic structure of this RBM gene is characterized by 12 exons and 11 introns. There is considerable homology among exons VII, VIII, IX, and X; each encodes one of the SRGY boxes. Several introns also have a high degree of homology among them (introns VI, VII, VIII, and IX). Eleven of the 12 exons have complete sequence homology with the RBM-1 sequence. There is 1 base difference in exon IV at position 495 (a T in the previously published DNA sequence vs. an A in the sequence reported here). The exonic sequences of this gene are distinct from that of the RBM-2 gene. The flanking sequences at the exon-intron junctions were also determined and are reported. Reverse transcription-PCR analysis, using human testis ribonucleic acid suggests that this gene is either not expressed in the testis or, more likely, the single base difference from RBM1 represents a polymorphism in the YAC clone. A high degree of homology between intronic and exonic sequences within the same gene and between different members of the RBM gene family (data not reported in this paper) suggests origin from common ancestral sequences; this also indicates that development of a single strand conformation polymorphism approach for detection of point mutations is likely to prove difficult for some of the exons of this gene.

Base Sequence↗
PubMed1989

Neurons expressing thyrotropin-releasing hormone-like messenger ribonucleic acid are widely distributed in Xenopus laevis brain.

Neurons containing messenger ribonucleic acid encoding thyrotropin-releasing hormone (TRH) in the brain of Xenopus laevis were visualized using in situ hybridization histochemistry. TRH-like mRNA-containing cells were detected in each coronal section tested, from the rostral tip of the telencephalon to the brainstem. In the telencephalon, labeled cells were observed in the olfactory nucleus, nucleus accumbens, striatum, diagonal band, and amygdala. Many intensely labeled cells were found in the hypothalamus, especially the preoptic nucleus and infundibular nuclei (dorsal and ventral). TRH-like mRNA-containing cells were also observed in the thalamus, optic tectum, and brain stem. These results suggest that the TRH neuronal system of X. laevis is organized in a manner similar to that of mammals, in that it is widely distributed throughout forebrain. However, Northern blot analysis of RNA extracted from Xenopus brain indicated that additional mRNAs possessing a TRH-like sequence may be present, suggesting that the regulation of TRH gene expression in Xenopus is different from that of the rat.

Animals↗
PubMed1997

Effect of dietary ribonucleic acid on bacterial translocationand survival following blood transfusion and thermal injury.

Ribonucleic acid (RNA) has been shown to have a key role in the maintenance of normal cellular function and host resistance to infection. The effect of experimental diets containing RNA on microbial translocation, killing of translocated bacteria and the survival rate of the host was studied in a burn animal model which included immunosuppression. Balb/c mice were fed for 10 days with an RNA supplemented diet (AIN/76A). Control groups were fed with two commercial diets: AIN-76A or Purina chow 5001 (chow). After 10 days of feeding, all animals received an allogenic transfusion. On day 15 the animals were gavaged with 10(10)(14)C radiolabeled or unlabeled Escherichia coli, and given a 20% total body surface area (TBSA) burn injury. Animals gavaged with unlabeled bacteria were observed for survival (n = 60) and animals gavaged with labeled bacteria were sacrificed 4 h post-burn (n = 30) and the mesenteric lymph nodes, liver and spleen were harvested. Slightly less translocation was observed in the liver and spleen of animals fed on RNA diet. Bacterial counts were measured and the percentages of translocated organisms that survived in the tissues were calculated and showed no statistical differences between the three groups. Survival was 45% in RNA group versus 55% in the non-supplemented AIN-76A and 50% in the chow group. It is concluded that a diet enriched in RNA slightly affects bacterial translocation but does not affect survival after severe injury.

Journal Article↗
PubMed1981

Effects of procollagen peptides on the translation of type II collagen messenger ribonucleic acid and on collagen biosynthesis in chondrocytes.

Type II procollagen messenger ribonucleic acid (mRNA) was isolated from chick sternum and rat chondrosarcoma cells and translated in a reticulocyte lysate cell-free system. A high molecular weight band was identified as type II procollagen by gel electrophoresis, collagenase digestion, and specific immunoprecipitation. The translation of type II mRNA was specifically inhibited by addition of type I procollagen amino-terminal extension peptide. When this peptide was added to the media of cultured fetal calf chondrocytes, chick sternal chondrocytes, or chick tendon fibroblasts, no inhibition of collagen synthesis was evident. These data suggest a general regulation of collagen biosynthesis by these peptides in the cell-free translation system. However, as indicated by the cell culture experiments, cellular characteristics and evolutionary divergence of animal species seem to restrict the effect of the peptides.

Animals↗
PubMed1976

Ribonucleic acid synthesis in normal and immune macrophages after antigenic stimulus.

Macrophage ribonucleic acid (RNA) synthesis is an important metabolic process intimately related to the function of these cells. Mouse peritoneal macrophage RNA was extracted with phenol in the presence of bentonite and electrophoresed on composite agarose-polyacrylamide gels. The pulse-chase technique was used to follow the precursor relationships in macrophage ribosomal RNA (rRNA) maturation. The rRNA species at 18S and 28S appeared at 15 and 45 min, respectively, after RNA synthesis was halted. Their appearance corresponded closely to decreases in the rRNA precursors at 45S, 36S, and 34S. Studies of RNA methylation aided in confirming the identity of these ribosomal species. Unmethylated RNA species appeared as messenger RNA between 5S and 15S, and at about 55S probably represented heterodisperse nuclear RNA. When normal macrophages were incubated with heat-killed Salmonella enteritidis, an acceleration in the maturation of RNA was observed. The accelerated maturation was indicated by the earlier appearance of 28S rRNA and the more rapid development of an equilibrium state, where further labeling did not change the RNA profile. In macrophage RNA from mice immunized with S. enteritidis, rRNA species appeared rapidly but did not accumulate to the same extent as observed for normal macrophages. Precursor rRNA and other RNA species developed as usual, suggesting specific degradation of mature rRNA. Such rRNA wastage could indicate a mechanism controlling ribosome assembly in the non-proliferating activated macrophage. The pattern of RNA synthesis in immune macrophages was essentially unchanged by the presence of heat-killed S. enteritidis in vitro.

Animals↗
PubMed1973

Control of arginine biosynthesis in Escherichia coli: role of arginyl-transfer ribonucleic acid synthetase in repression.

The physiological role of arginyl-transfer ribonucleic acid (Arg-tRNA) synthetase (E.C. 6.1.1.13, arginine: RNA ligase adenosine monophosphate) in repression of arginine biosynthetic enzymes was examined. Mutants with nonrepressible synthesis of arginine biosynthetic enzymes were isolated from various strains of Escherichia coli by resistance to growth inhibition by canavanine, an arginine analogue. These mutants possessed reduced Arg-tRNA synthetase activities which were qualitatively different from the synthetase activity of the wild type. The mutant enzymes exhibited turnover in vivo and were less stable in vitro than the wild type at both 4 C and 40 C; they possessed different affinities for both arginine and canavanine as measured by the three common assay systems for aminoacyl-tRNA synthetases. Furthermore, in one case it was shown that (i) the mutant possesed unaltered uptake of arginine, and (ii) that the mutant possessed diminished ability to incorporate canavanine into proteins and to attach canavanine to tRNA. These observations suggested that the mutation to canavanine resistance involved a structural change in Arg-tRNA synthetase. Likewise, the results of genetic experiments suggested that the mutants differed from the wild-type strain at only one locus, and that this lies in the region of the chromosomes that includes a structural gene for Arg-tRNA synthetase. It appears that Arg-tRNA synthetase may be involved in some way in repression by arginine of its own biosynthetic enzymes.

Amino Acyl-tRNA Synthetases↗
PubMed1975

Characterization of 5.8S ribosomal ribonucleic acid in Neurospora crassa.

Neurospora crassa ribosomes contain a species of ribonucleic acid (RNA) of molecular weight 54,000, similar to 5.8S ribosomal RNA previously described for other eukaryotic organisms. The 5.8S RNA from N. crassa was found to be released by heat treatment at 60 C from 25S ribosomal RNA but not from 18S ribosomal RNA. The base composition of N. crassa 5.8S RNA was similar to that of 5.8S RNA from Saccharomyces cerevisiae, but differed from animal 5.8S RNA. During the course of this study, it was discovered that N. crassa 25S ribosomal RNA had a number of internal cleavages that may exist in vivo.

Cytidine↗
PubMed1975

Association of nascent ribosomal ribonucleic acid with polyribosomes in Escherichia coli.

Sedimentation distributions of rapidly labeled ribonucleic acid (RNA) in extracts prepared from cells labeled for 60 s or less with [3H]uridine showed that the immature ribosome precursor particles themselves have an RNA precursor which sediments with polyribosomes and 70s ribosomes. In extracts prepared from cultures labeled for 30 s, the fraction of labeled RNA which did not sediment with polyribosomes was much less than the fraction which was ribosomal RNA (rRNA). Rapidly labeled RNA associated with polyribosomes had a nucleotide base composition consistent with the presence of rRNA, and was shown by RNA-deoxyribonucleic acid hybridization to contain 30 to 40% rRNA. Nascent rRNA is thus associated with polyribosomes during its transcription. The sedimentation distribution of rapidly labeled 16s and 23s rRNA showed that these molecules are separated during transcription and associated with different polyribosomes.

Azides↗