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At least 865 records · Page 48Linked to original sources

PubMed1978

[Possible role of neuropeptides in regulating nucleic acid biosynthesis in the brain].

It has been studied the role of intracysternal administration of neuropeptides--five analogous of 8-lysinvasopressin (LVP) [Des-9-Gly-cine-amide-LVP (DGLVP), Tri-Gly-LVP, deamino-LVP (1--beta-mercaptopropionic acid-LVP), Leu4-LVP, Asn1,6-LVP] and two cardiotrop hexapeptides (acetylated and non) separated from the hypothalamus in the regulation of various types of RNA (GC and AU types n-RNA, r-RNA, t-RNA) biosynthesis in the brain. Using the combined method of phenol extraction, differential ultracentrifugation, gel-filtration and ultraviolet spectroscory of various types of RNA has been shown the increase in the content of r-RNA and t-RNA under the influence of DGLVP, Leu4-LVP and cardiotrop hexapeptide. Deamino-LVP, Tri-Gly-LVP and acetylated hexapeptide stimulate the rise in the content of r-RNA and AU type n-RNA (precursor of m-RNA). Ans1,6-LVP shows a nonspecific influence on the biosynthesis of the brain RNA. It has been suggested a hypothesis about a participation of the neuropeptides in the regulation of various types of the brain RNA biosynthesis, as a primary messanger (starting signals) during the stimulation of the initiation of cycloadenylate- and cycloguanylate-sensitive transcription, via phosphorylation of diverse RNA-polymerases. It was given a scheme of interaction between the messanger conception of neuropeptides and cyclic-3', 5'-monophosphate nucleotide-dependent transcription by which the cycloadenylate-dependent transcription appears to play a great role in the r-RNA and t-RNA biosynthesis and the cycloguanylate-dependent transcription -- in the biosynthesis of m-RNA.

Amanitins↗

PubMedDate not supplied

[The time-dependent stimulating action of hydrocortisone on mitochondrial RNA biosynthesis in the rat liver].

Mitochondrial RNA biosynthesis was studied at different time after hydrocortisone administration. Hydrocortisone induced liver mitochondrial RNA biosynthesis in vivo and in isolated organellae 15 min., 1.5 and 4 h after hormone injection. As shown by means of molecular hybridization of RNA-DNA, an increase in liver mitochondrial RNA biosynthesis induced by hydrocortisone administration was due to an increase in the expression of all mitochondrial genes simultaneously rather than to selective enhancement of individual gene transcription. Hydrocortisone changed the biosynthesis and transport of cytoplasmic RNA in the liver of intact rats. The incorporation of 3H-UTP into RNA by isolated liver mitochondria of control and hydrocortisone-treated rats was inhibited by ethidium bromide. RNA biosynthesis in isolated rat liver mitochondria was unchanged in 15-300 min. of 0.9% NaCl administration.

Animals↗

PubMed1987

Thromboxane A2 biosynthesis in human disease.

Thromboxane A2 (TxA2), the predominant cyclooxygenase product of human platelets, is a potent vasoconstrictor and platelet agonist. Although its biological properties are readily appreciable in vitro, it has been difficult to define its biological importance in vivo. To a large extent this reflected the problems associated with efforts to monitor biosynthesis of this eicosanoid and the lack of selective pharmacological probes that prevented the synthesis of TxA2 or antagonized its biological action in vivo. Recently the analysis of urinary metabolites of TxB2 has become simplified so that the methodology is readily applicable to clinical studies. This provides a noninvasive, time-integrated index of Tx biosynthesis. Although one cannot definitively establish a tissue of origin for metabolites measured in urine, indirect evidence suggests that urinary TxB2 derives primarily from the kidney whereas its dinor metabolite predominantly reflects platelet biosynthesis under physiological conditions. Although plasma concentrations of TxB2 are readily confounded by platelet activation ex vivo, the enzymatic metabolites formed from TxB2 have recently been identified and appear to bypass this problem. Combined analysis of long-lived (e.g., 11-dehydro-TxB2) and short-lived (e.g., 2,3-dinor-TxB2) metabolites in plasma promise to more accurately localize phasic increases in the biosynthesis of TxA2 and have been paralleled by the development of antagonists of the TxA2/prostaglandin endoperoxide receptor and their study of humans. The use of such specific probes in conditions characterized by abnormal biosynthesis of TxA2 promises to define the biological role of this mediator for humans.

Arachidonic Acid↗

PubMed1988

The role of redox in the regulation of manganese-containing superoxide dismutase biosynthesis in Escherichia coli.

The manganese-containing superoxide dismutase in Escherichia coli is an inducible enzyme that protects cells against oxygen toxicity. The manganese-enzyme is induced by oxygen, nitrate, redox active compounds that react with oxygen to generate superoxide radicals, as well as iron chelators. In order to test the hypothesis that the redox state of the cell is involved in regulating manganese-superoxide dismutase biosynthesis, we studied the effects of several oxidants on growth and superoxide dismutase biosynthesis. The data showed, that under anaerobic conditions, the active manganese-enzyme is induced in the presence of potassium ferricyanide, copper-cyanide complex, ammonium persulfate, and hydrogen peroxide. Western blot analysis revealed that the induction of manganese-superoxide dismutase by the oxidants is associated with de novo protein biosynthesis. Potassium ferricyanide and hydrogen peroxide induced the enzyme under aerobic conditions as well. It is concluded that the redox state of the cell possibly influences the biosynthesis and/or activity of an iron-containing repressor protein that serves to negatively regulate manganese-superoxide dismutase biosynthesis.

Ammonium Sulfate↗

PubMed1988

Biosynthesis of MAM-6, an epithelial sialomucin. Evidence for involvement of a rare proteolytic cleavage step in the endoplasmic reticulum.

MAM-6 is a major epithelial sialomucin which is abundantly present at the apical surface of ductal and alveolar cells of normal tissues and on many different carcinoma cells. MAM-6, as defined by monoclonal antibodies, consists of one or two sialylated glycoproteins with apparent molecular masses of over 400 kDa under reducing as well as nonreducing conditions. The mobility and number of glycoproteins immunoprecipitated vary depending on the cell line of origin. We have employed immunoprecipitation techniques to study the biosynthesis and glycosylation of this mucin. The biosynthesis of MAM-6 was studied in the ZR-75-1 breast cancer cell line. Two glycoproteins with apparent molecular masses of approximately 450 and 650 kDa, representing the mature form, were immunoprecipitated. By pulse-chase analysis, we show that the biosynthesis of the 450-kDa glycoprotein proceeded through intermediates of 220, 200, and 500 kDa which became perceptible after 1, 4, and 30 min, respectively. The biosynthesis of the 650-kDa glycoprotein followed a similar course through 380, 350, and 700-kDa intermediates. The processing of the 220- and 350-kDa precursors involves a rare proteolytic cleavage step which occurs in the endoplasmic reticulum. The late precursors of 500/700 kDa, observed after 30 min chase, and the mature glycoproteins were generated by extensive O-linked glycosylation. The formation of the 500/700-kDa precursors was not affected by monensin. However, the final step of maturation, sialylation of the 500/700-kDa precursors, could be inhibited by monensin. The extensive O-linked glycosylation causes the apparent high molecular weight as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Our data on the biosynthesis show that the early MAM-6 precursors contain N-linked glycans, suggesting the presence of N-linked glycans on the mature MAM-6 molecule. Although the copresence of N- and O-linked glycans has been found on many molecules, no N-linked glycans have been reported on mucus glycoproteins previously.

Breast Neoplasms↗

PubMed1988

[Effect of L-arabinose and sucrose on the biosynthesis of heliomycin by its producer Streptomyces olivocinereus 11-98].

When Streptomyces olivocinereus 11-98 MFU was grown in media containing L-arabinose or sucrose there was observed a converse relation between the culture growth and heliomycin biosynthesis. In media with two carbon sources: L-arabinose and glycerol or sucrose and glycerol at first L-arabinose or sucrose was consumed while the level of glycerol consumption remained low as compared to the control. After exhaustion of the first carbon source there was observed increased consumption of the second one i.e. glycerol. While the medium contained L-arabinose or sucrose the culture growth was mainly provided by these carbon sources and biosynthesis of heliomycin was inhibited. The culture started biosynthesis of heliomycin when L-arabinose or sucrose in the medium was exhausted. Probably control of heliomycin biosynthesis by L-arabinose or sucrose is achieved by catabolic type carbon regulation known as the general mechanism regulating biosynthesis of various antibiotics.

Anti-Bacterial Agents↗

PubMedDate not supplied

Biosynthesis of the luteinizing hormone releasing hormone (LH-RH) in the rat hypothalamus.

The biosynthesis of LH-RH was followed and evaluated in the hypothalamus of intact and castrated female rats after the infusion into the 3rd cerebral ventricle of L-3H-Glycine and its incorporation into the synthetized hormone. Incorporation of 3H-Gly into the LH--RH molecule that means biosynthesis of this hormone was found 30 min after the infusion of labeled amino acid. The incorporation rate in castrated animals was 2 times higher than in intact ones. Estradiol-17 beta only slightly depressed the LH--RH biosynthesis rate in castrated animals. Pretreatment with cycloheximide or puromycin decreased biosynthesis rate of the hormone by 50%. On the basis of cycloheximide and puromycin action it is suggested that the ribosomes are involved in the biosynthesis of LH--RH.

Animals↗

PubMed1987

[Effect of stress and the antioxidant ionol on the biosynthesis of catecholamines and the content of dopamine in the heart and adrenal glands].

The effects of a synthetic antioxidant ionol (dibunol) on the biosynthesis and content of catecholamines in the heart and adrenal glands were studied. It was shown that in stress a mobilization of catecholamine reserve is combined with a considerable increase in dopamine concentration. In conditions of physiological rest, ionol did not affect the studied indices of adrenal catecholamine biosynthesis, while in the heart it enhanced the dopamine synthesis and content. With ionol administration, stress did not suppress but, on the contrary, increased the neuronal uptake and noradrenaline biosynthesis, catecholamine concentration remaining practically unchanged. Simultaneously, a manyfold increase in the biosynthesis along with a considerable increase in the concentration of dopamine developed in both organs. The data obtained suggest that ionol realizes its stress-defensive effect to a great extent due to the activation of catecholamine biosynthesis and to a concomitant increase in dopamine accumulation.

Adrenal Glands↗

PubMed1985

[Inhibition of oleandomycin biosynthesis by glucose].

The results of the study on the effect of glucose and various carbohydrates on biosynthesis of oleandomycin by Streptomyces antibioticus are presented. It was found that glucose added at the beginning or by the 48th hour of the fermentation process on the complex medium inhibited oleandomycin biosynthesis. To investigate the mechanism of the glucose effect, a fermentation medium was developed. It provided variation of the carbohydrate composition, determination of the protein content in the culture and evaluation of the mycelium productivity. With the use of this medium it was shown that monosaccharides such as galactose, fructose and glucose significantly activated the mycelium growth as compared to lactose and sucrose. At the same time glucose completely inhibited oleandomycin biosynthesis when added either as an only carbohydrate component or in combination with galactose or fructose, while the presence of the other two monosaccharides did not prevent antibiotic production, though the mycelium productivity was lowered as compared to that with the use of the disaccharide. Therefore, the inhibitory effect of glucose on biosynthesis of oleandomycin was not connected with activation of the culture growth by it. Acidification of the medium on cultivation of the streptomycete in the presence of glucose only partially explained its inhibitory effect, since inhibition was maintained on the medium with addition of CaCO3 which stabilizes pH. Addition of 2-deoxy-D-glucose, a nonmetabolized glucose analog, to the fermentation medium retarded antibiotic production. It is possible that the inhibitory effect of glucose on biosynthesis of oleandomycin is not associated with its metabolism.

Culture Media↗

PubMed1966

RNA biosynthesis in adipose tissue: effect of fasting.

RNA metabolism has been examined in intact adipose tissue and isolated fat cells from rats. The lipocyte contains three species of RNA with sedimentation rates corresponding to those of ribosomal and transfer RNA. The de novo biosynthesis of RNA by adipose tissue cells in vitro was demonstrated. The base ratios of the RNA formed indicate that it was synthesized from a DNA template. Actinomycin D administered in vivo and in vitro decreased total RNA synthesis with the most marked effect on the synthesis of the heavy RNA components. Actinomycin D or puromycin added in vitro was not toxic: they did not inhibit total fatty acid biosynthesis or glucose utilization by the fat pad nor did they inhibit the immediate stimulation of fatty acid biosynthesis and glucose uptake by the addition of insulin in vitro. Starvation for 48-72 hr significantly depressed the synthesis of the heavy RNA components as measured by in vitro uridine incorporation into the individual RNA classes. Refeeding the fasted rat with glucose repaired the defect in RNA biosynthesis before the biosynthesis of monoenoic fatty acid was completely restored. Actinomycin D administered at the time of refeeding prevented the repair of monoenoic fatty acid synthesis. It is concluded that RNA metabolism is intimately involved in the control of biosynthetic reactions in adipose tissue.

Adipose Tissue↗

PubMed1980

[Effect of cyclic adenosine-3,5-monophosphate and its dibutyryl analog on macromolecule biosynthesis in actively proliferating cells].

The effect of cAMP and its dibutyryl analogue on the biosynthesis of nucleic acids and protein in active proliferating cells was studied. It was shown that cAMP (10(-3)--10(-4)M) caused stimulation of the biosynthesis of DNA and RNA in Ehrlich's ascites carcinoma (EAC) cells and intensification of collagen biosynthesis in the chick embryo cartilage tissue in vitro. Dibutyryl -- cAMP (10(-3)--10(-4)M) has an inhibitory action on the biosynthesis of macromolecules both in EAC cells and embryonic cartilage tissue. Addition of cAMP phosphodiesterase inhibitors together with cAMP to the incubation media prevents the stimulation of macromolecular biosynthesis observed under the influence of cAMP. Studies on cAMP metabolism revealed that this compound is rapidly catabolized to AMP and adenosine. The latter enters the cells and incorporates into the adenyl nucleotide intracellular pool. The stimulant action of exogenous cAMP is related to its extracellular metabolism rather than to the intracellular effects of the nucleotide.

Animals↗

PubMedDate not supplied

Fetal hemoglobin biosynthesis in clonal cell culture.

Availability of the clonal erythropoietic cell culture methods provided a unique opportunity to study human hemoglobin biosynthesis under controlled conditions. Observations in several laboratories during the last four years fundamentally agree and can be summarized as follows: (1) Biosynthesis of fetal hemoglobin (HbF) is markedly augmented in cultures of adult erythropoietic precursors. (2) HbF biosynthetic capabilities inversely parallel the maturational stages of adult erythropoietic precursors in the marrow. (3) Adult circulating precursors (BFU-e) are also capable of augmented HbF biosynthesis in culture. (4) The pattern of Hb synthesized by fetal erythropoietic precursors corresponds very closely to the Hb compositions in the mature erythrocytes of the donors. (5) Burst-promoting activities (BPA) rather than erythropoietin (Ep) appear to stimulate HbF biosynthesis by augmentation of proliferation of precursors which are programmed to produce F cells in vivo. (6) Individual BFU-e are heterogeneously committed to HbF biosynthesis and their frequency distributions reveal normal distributions. (7) Increase in HbF production in culture is primarily due to increased production of the number of cells containing Hbf. (8) Commitment to produce HbF continues during subcolony formation in culture. (9)HbF synthesized in culture of adult and umbilical cord blood BFU-e reveal "adult" and "intermediate" values of G gamma:A gamma ratios, respectively. (1)) Frequency distributions of individual bursts varying in relative G gamma synthesis (G gamma/[G gamma+A gamma]) reveal unimodal distributions. (11) Positive correlations exist between gamma/(gamma+beta) and G gamma/(G gamma + A gamma) values in individual bursts.

Bone Marrow↗

PubMedDate not supplied

[Regulation of the biosynthesis of endo-1,4-beta-glucanase, eco-1,4-beta-glucosidase and cellobiase in Aspergillus terreus].

This work was aimed at studying how the biosynthesis of endo-1,4-beta-glucanase, exo-1,4-beta-glucosidase and cellobiase, components of the cellulase complex was regulated in an Aspergillus terreus strain isolated from soil. The biosynthesis of endoglucanase and cellobiase was suppressed by readily metabolizable substrates and stimulated in the course of growth on lactose and celluloses. The activity of exoglucosidase was found in the medium only when the strain was grown on celluloses. Catabolite repression was assumed to be an important mechanism regulating the biosynthesis of cellulases by the culture. The derepression was insufficient however to stimulate the biosynthesis of all the three enzymes. Besides lactose and celluloses, cellobiose taken at a low concentration also exhibited the inducing effect. Under the conditions of derepression and induction, the activity of the three enzymes, the components of the complex, increases in the growth medium in parallel to the cultural growth. The synthesis and excretion of endoglucanase and exoglucosidase coincided in time whereas a considerable portion of the cellobiase activity was displayed by the cells. The results suggest that the regulation of endoglucanase, exoglucosidase and cellobiase biosynthesis are coordinated at the level of catabolite repression and induction.

Aspergillus↗

PubMed1984

[Combined therapy with polyamine biosynthesis inhibitors and mitomycin C].

An attempt was made to analyse tumor growth after cessation of combined therapy with the polyamine biosynthesis inhibitors, alpha-difluoromethylornithine (DFMO) and methylglyoxal-bis-guanylhydrazone (MGBG), as well as mitomycin C (MMC). DFMO 1000 mg/kg, MGBG 50 mg/kg and/or MMC 2 mg/kg were given intraperitoneally to BALB/c nu/nu mice xenotransplanted human gastric cancer, and its growth as well as DNA biosynthesis were measured daily, after cessation of these combined treatments. Histological observation of the tumor was also performed by hematoxylin-eosin staining. The combination with DFMO and MGBG stunted tumor growth during the treatment, but 3 days later its growth and DNA biosynthesis were accelerated distinctly. MMC injection halted tumor growth, and 5 days after termination of MMC injection its growth rate and DNA biosynthesis almost completely recovered. The microscopic findings on the 4th day after termination of MMC injection were similar to those of DFMO + MGBG treatment. The combination DFMO, MGBG and MMC suppressed not only tumor growth during the treatment, but also tumor growth and DNA biosynthesis over 7 days. The histologic observation 4 days later revealed extensive damage.

Animals↗

PubMed1983

Glycogen content and lipid biosynthesis in the lungs of fetuses of diabetic rats.

The fetal pulmonary glycogen content and the pulmonary biosynthesis of neutral lipids and phospholipids were estimated at gestational days 18, 20, and 22 in the offspring of normal, manifest diabetic, and insulin-treated diabetic rats. In all groups the fetal pulmonary glycogen concentration was highest on gestational day 20 and decreased during the subsequent 2 days. At the same time the biosynthesis of neutral lipids and phospholipids increased in the fetal lungs. The fetuses of the manifest diabetic rats showed an increased glycogen concentration and decreased total lipid biosynthesis compared with the other two groups. Insulin treatment of the rat mothers largely normalized the pulmonary lipid biosynthesis and glycogen accumulation in their fetuses. These data suggest that the diabetic maternal environment induces a transient block in the fetal utilization of pulmonary glycogen for the biosynthesis of lipids, in particular for the production of surfactant phospholipids.

Animals↗

PubMed1982

Sites and regulation of carnitine biosynthesis in mammals.

Although the pathway of carnitine biosynthesis in mammals is known, the location of active synthesis of carnitine and regulation of the pathway have not been clearly defined. Studies in several laboratories have shown that the enzymes that collectively convert epsilon-N-trimethyllysine (epsilon-N-TML) to gamma-butyrobetaine are found in all tissues studied in rats and humans, but distribution of the final enzyme of the pathway, gamma-butyrobetaine, 2-oxoglutarate dioxygenase (gamma-butyrobetaine hydroxylase) is variable from one species to another. Evidence from studies in rats and humans indicates that uptake and metabolism of epsilon-N-TML by the kidney is necessary for carnitine biosynthesis from circulating epsilon-N-TML. Limited data now available suggest that some of the intracellularly derived epsilon-N-TML is metabolized to gamma-butyrobetaine and carnitine in the tissue of origin, and some is released into the circulation. epsilon-N-TML in mammals is apparently derived from lysine residues in proteins, which are methylated and later released by protein hydrolysis. This source probably provides sufficient substrate for carnitine biosynthesis. Carnitine biosynthesis from epsilon-N-TML is not regulated by end-product feedback mechanisms. Hepatic gamma-butyrobetaine hydroxylase activity in rats and humans is developmentally regulated, and is increased by dietary L-thyroxine in adult rats. No other mechanisms for regulation of carnitine biosynthesis have been identified.

Adult↗

PubMedDate not supplied

[Cortisol inhibition of cholesterol and phospholipid biosynthesis in the rat liver].

Effect of hydrocortisone on biosynthesis of cholesterol and phospholipids in liver tissue was studied using intact rats, in adrenalectomy, under conditions of stimulation of lipid biosynthesis by cholestyramine and Triton WR-1339. Hydrocortisone was shown to inhibit biosynthesis of cholesterol and phospholipids in rat liver tissue if 2-14C-acetate was used as a precursor. The hormone inhibited biosynthesis of lipid components in membranes of adrenalectomized rats. Under conditions of preactivation of the lipid biosynthesis, using simulation with cholestyramine and Trition WR-1339, hydrocortisone decreased the synthesis of cholesterol and phospholipids.

Adrenalectomy↗

PubMed1993

C1-inhibitor-serine proteinase complexes and the biosynthesis of C1-inhibitor by Hep G2 and U 937 cells.

The biosynthesis of the serpin alpha 1-proteinase inhibitor is regulated by a feedback mechanism whereby complexes between alpha 1-proteinase inhibitor and serine proteinases bind to liver cells and monocytes, a reaction that activates alpha 1-proteinase-inhibitor gene transcription. Such a mechanism may form the basis for the development of new therapeutic strategies for serpin deficiency states with reduced levels of otherwise normally functioning serpins. This issue was addressed for C1-inhibitor, the missing serpin in hereditary angioedema. C1-inhibitor biosynthesis by Hep G2 hepatoma cells was assessed by enzyme-linked immunosorbant assay, by metabolic labeling followed by immunoprecipitation, and by Northern blotting. C1-inhibitor biosynthesis was stimulated by gamma-interferon (100 U/mL) but not by cell exposure to C1-inhibitor-kallikrein (1 mumol/L), C1-inhibitor-C1s (1 mumol/L), and C1-inhibitor-plasmin complexes (1 mumol/L) or to reactive site-cleaved C1-inhibitor (1 mumol/L). Moreover, radioiodinated C1s-C1-inhibitor complex did not bind to Hep G2 cells. C1-inhibitor-kallikrein complex was also without effect on C1-inhibitor mRNA in U 937 cells. Therefore, the proposed mechanism, by which serpin-enzyme complex or reactive site-cleaved serpin binding to a specific receptor provides a signal for the stimulation of the biosynthesis of that serpin, is not operative for the biosynthesis of C1-inhibitor by Hep G2 or U 937 cells.

Amino Acid Sequence↗