SEARCH · PubMed Health

Results for “Dual control”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources

PubMed1984

Adrenergic innervation of the tunica media in the saphenous artery of the fetal and newborn guinea-pig.

Previous studies have demonstrated that adrenergic nerves are located in the medial-adventitial border of the muscular arteries. Observations made in this study have revealed that adrenergic nerves penetrate into the outer medial layer of the saphenous artery in fetal and newborn guinea-pigs, while in the adult these nerves are located in the medial-adventitial border. It is proposed that the adrenergic nerves located in the tunica media may have a trophic effect on the medial smooth muscle. It is further suggested that the final refinement of the dual control system of arterial walls, by nerves and circulating catecholamines, involves exclusion of adrenergic nerves from the tunica media.

Adrenergic Fibers↗

PubMed1984

The hypothalamo-hypophysial system of the wild carp, Cyprinus carpio L. I. Structure and ultrastructure of the posterior neurohypophysis.

The posterior neurohypophysis (PNH)-pars intermedia complex of the wild and pond carp, Cyprinus carpio L., has been studied by light, fluorescence and electron microscopy. "Gomori-positive" neurosecretory fibres are abundant in the main trunk of the neurohypophysis as well as its roots penetrating the pars intermedia. Terminals of these fibres are in contact with capillaries of the general circulation and with glandular cells of the pars intermedia. Monoaminergic fibres with a weak green fluorescence, somewhat increasing after injection of nialamide into the pond carp, have largely the same distribution. Three types of neurosecretory fibres and their terminals have been recognized in the PNH-pars intermedia complex. Types-A1 and -A2 fibres, containing granules of 140-180 nm and 100-160 nm in diameter respectively, are peptidergic "Gomori-positive". Type-A2 fibres predominate in the PNH. The least frequent monoaminergic type-B fibres have granules of 60-100 nm in diameter. Numerous peptidergic and few monoaminergic neurosecretory terminals make contact with the capillaries located within the roots of the PNH as well as at the border between them and the pars intermedia. Both peptidergic and monoaminergic terminals make direct synaptoid contacts with the gland cells or end close to connective tissue septa, basal lamina or pituicytes. The PAS-positive gland cells and to a lesser degree the lead-haematoxylin-positive gland cells show these relationships with neurosecretory terminals. The question concerning the mode of interaction between peptidergic and monoaminergic structures in the dual control of the gland cells of the pars intermedia of teleosts is discussed.

Animals↗

PubMed1991

The requirement of ArcA and Fnr for peak expression of the cyd operon in Escherichia coli under microaerobic conditions.

Transcriptional regulation of cyd, encoding the cytochrome d complex for O2 scavenging, was studied in Escherichia coli by monitoring phi(cyd-lac) expression under atmospheres containing 0-21% O2. Peak expression of this operon occurred under microaerobic conditions. Mutations in arcA (a trans-acting regulatory gene involved in aerobic respiration) greatly lowered phi(cyd-lac) expression under all conditions. Mutations in fnr (a trans-acting regulatory gene involved in anaerobic respiration) shifted the pattern of phi(cyd-lac) expression, lowering the microaerobic and aerobic expression. In an arcA-fnr double mutant, phi(cyd-lac) expression became insignificant, irrespective of the availability of O2. It thus appears that the expression of the phi(cyd-lac) operon is under dual control by the two pleiotropic activators, ArcA and Fnr, which interact to give the peak microaerobic expression.

Aerobiosis↗

PubMed1985

Genetic analysis of uxuR and exuR genes: evidence for ExuR and UxuR monomer repressors interactions.

The uxuAB operon is under the dual control of uxuR- and exuR-encoded repressors whereas the exu regulon genes are regulated by the sole ExuR repressor. Mutations affecting the two exuR and uxuR regulatory genes were selected to investigate the relationship between the two repressors. The isolation of exuR and uxuR negative dominant mutations on a multicopy plasmid indicated that the active form of the two repressors was multimeric. The introduction of a uxuR negative dominant allele into a wild-type strain resulted in a significant increase in exu gene expression. This unexpected effect may have been the consequence of the formation of hybrid repressor molecules. This protein must be composed of native ExuR+ subunits aggregated with altered UxuR subunits. The same interference was observed for the exuR negative dominant allele on uxu gene derepression. The hypothesis given here implies that the two regions of the ExuR and UxuR repressors involved in the subunit aggregation present enough homologies to allow the formation of hybrid repressor molecules.

Carbohydrate Dehydrogenases↗

PubMed1995

Changes in stiffness induced by hindlimb suspension in rat soleus muscle.

Soleus muscle atrophy was induced by hind-limb suspension of rats for 3 weeks with the intention of inducing a relative increase in the percentage of fast-twitch fibres and assessing modifications in muscle stiffness. A method of dual controlled releases was used to obtain tension/extension curves and force/velocity relationships characterizing the mechanical behaviour of the soleus. Fibre typing was achieved by myofibrillar adenosine 5'-triphosphatase staining. Results showed that hindlimb suspension decreased the percentage of slow-twitch fibres (-31%) to the profit of fast-twitch fibres (+370%) and intermediate fibres (+255%). This led to an increase in maximal shortening velocity. Tension/extension curves indicated a decrease in soleus stiffness after 3 weeks of unloading. Changes in elastic properties are interpreted in terms of modifications occurring in the active part and the passive part of the so-called series elastic component. These changes also suggest that the parameters derived from a twitch are inappropriate to account for modifications in speed-related properties of muscle.

Adaptation, Physiological↗

PubMed1994

Effects of stretch-shortening cycle training on mechanical properties and fibre type transition in the rat soleus muscle.

The effects of exercise training on mechanical properties and fibre type transitions have been investigated in rat soleus muscles. The exercise was a repetition of stretch-shortening cycles. A method of dual controlled releases was applied to obtain tension/extension curves, which characterize the elastic behaviour of the series elastic component (SEC), and the force/velocity relationship characterizing the contractile elements. Other contractile measurements included: contraction time (tc), half-relaxation time (t1/2) and twitch/tetanus ratio (Pt/Po). Additionally, the muscle fibre type composition was determined by a classical histochemical method. A 12-week period of training induced a significantly higher percentage of fast-twitch fibres and a lower percentage of slow-twitch fibres (P < 0.01). This fibre adaptation led to a significant (P < 0.01) decrease in tc and an increase in maximum shortening velocity (Vmax). An increase in compliance of the SEC was also observed. This elastic adaptation is interpreted in terms of modification of the active components of the SEC. All the histochemical and mechanical data presented in this study show that rat soleus muscles trained by stretch-shortening cycles acquired faster characteristics. Thus the results confirm that a slow-twitch to a fast-twitch fibre transition is obtainable in mature rats.

Animals↗

PubMed1990

The solar wind and human birth rate: a possible relationship due to magnetic disturbances.

Data obtained from the literature on the annual pattern of human conceptions and plasma melatonin at high latitudes indicated that simple annual rhythms do not exist. Instead, prominent semiannual rhythms are found, with equinoctial troughs and solsticial peaks. A prominent semiannual environmental event is the magnetic disturbance induced by the solar wind. The semiannual magnetic disturbances are worldwide, but most pronounced in the auroral zones where the corpuscular radiation enters the atmosphere. Magnetic indices that predominantly reflect these events were obtained from the literature and correlated with the melatonin and conception data. Significant and inverse correlations were found for Inuit conceptions and the melatonin data. The correlations obtained for 48 contiguous states of the United States indicated that only the extreme northern states exhibited this relationship. These data were compared with a previous correlational study in the United States which established that sunshine was correlated with conceptions in the middle latitude and southern states. An hypothesis of dual control by electromagnetic and magnetic energies is proposed: melatonin is a progonadal hormone in humans controlled by both factors, depending on their relative strength. Other studies are reviewed regarding the possible factors involved in determining the annual pattern of human conceptions. Demographic studies of geographic variation in temporal patterns of conceptions, with particular regard to variations of the magnetic fields on the earth's surface, may provide some insight into the efficacy of these different factors.

Birth Rate↗

PubMed1994

Acceleration of desipramine-induced changes on the dopamine receptor-coupled adenylate cyclase system by pertussis toxin.

The response of adenylate cyclase to GTP and to dopamine (DA) was investigated in striatal membranes from desipramine (DMI)-treated rats (10 mg/kg, b.i.d., for 5 days). GPT exerted the same biphasic effect on basal and DA-stimulated enzyme activity in membranes from DMI-treated rats as on saline-treated rats. Rats were injected intraventricularly once with islet activating protein (IAP), pertussis toxin, and given extended treatment with DMI in order to study the effects on the inhibitory GTP-binding protein (Gi). Gi loses its function as a signal transducer on being ADP-ribosylated selectively by the IAP. D2 inhibition of adenylate cyclase by DA was attenuated by the IAP treatment in both DMI-and saline-treated rats; peak levels of DA plus GTP stimulation shifted from 1 microM to 100 microM GTP. D1 stimulation of adenylate cyclase by DA was also attenuated by the IAP in the DMI-treated rats. Since long-term treatment with DMI (15 mg/kg, once a day, for 3 weeks) resulted in suppression of D1 stimulation similar to that seen in the present findings, uncoupling between D2 receptors and Gi due to IAP treatment might accelerate DMI-induced adaptive changes of dual control of adenylate cyclase system by DA.

Adenosine Diphosphate Ribose↗

PubMed1988

[Guanidine nucleotide binding proteins as membrane signal transduction components and regulators of enzymatic effectors].

The vast majority of extracellular signals alters cell function by activating cell surface receptors. The transmembranous signalling process initiated by an activated receptor leads to the generation of an intracellular signal and eventually to a cellular response. In contrast to receptors that are permanently coupled to an enzyme or an ion channel representing the effector, a large number of surface receptors for hormones, neurotransmitters and receptors for exogenous chemical or physical stimuli reversibly interacts with membranous signal transduction components which, in turn, regulate intracellular messenger-generating effectors. The transducer molecules isolated so far form a family of guanine nucleotide-binding proteins (G- or N-proteins). All isolated G-proteins are composed of three different subunits (alpha, beta, gamma). The alpha-subunit, which is specific for the individual G-protein, binds and hydrolyzes GTP and is target of ADP-ribosylating bacterial toxins. Hormone-induced activation of a receptor causes interaction with the alpha-subunit of a G-protein and the exchange of bound GDP with GTP. The GTP-bound form of the alpha-subunit represents the active form of the G-protein, which is capable of stimulating or inhibiting the respective effector. The active state of the alpha-subunit is terminated by its inherent GTPase activity causing hydrolysis of bound GTP. The beta gamma-complexes of G-proteins are structurally very similar and functionally interchangeable; they appear to dissociate from the alpha-subunits during receptor activation of the G-protein. Possible functions of the beta gamma-complex are to anchor the non-activated G-protein in the membrane, to facilitate G-protein-receptor interaction, and to promote the inactive state of the alpha-subunit. G-protein-regulated effectors include enzymes, ion channels and probably transporters. The best studied G-protein-regulated enzyme is the retinal cyclic GMP-phosphodiesterase which is activated by bleached rhodopsin via the tissue-specific G-protein, termed transducin. The ubiquitously occurring membrane-bound adenylate cyclase is under dual control by families of stimulatory and inhibitory receptors, acting via G-proteins called Gs and Gi, respectively. Moreover, the receptor control of phospholipases A2 and C and probably of phospholipase D most likely involves G-proteins which have not yet been identified. Finally, the activity of NADPH oxidase of neutrophils and that of cyclic AMP phosphodiesterases in liver and fat cells may be regulated via G-proteins. Modulations of non-enzymatic effectors are reviewed elsewhere.

Animals↗

PubMed1996

Requirement for two conserved cysteine residues in the Ada protein of Escherichia coli for transactivation of the ada promoter.

Cysteine residue 69 of the Escherichia coli Ada transcription factor, which accepts a methyl group from methylphosphotriester in methylated DNA, was substituted by each of 19 other amino acids. Only the mutant Ada (C69H), carrying a histidine substitution of Cys69, exhibited a limited degree of transactivating potential for the ada promoter in E. coli cells although the mutant protein was completely devoid of methylphosphotriester-DNA methyltransferase activity. Using a multicopy plasmid system for the expression of Ada protein, we have shown that Ada C69H has a transactivating capacity equivalent to that of wild-type Ada protein in the absence of an alkylating agent. This indicates that the zinc-binding capacity of histidine at residue 69 is likely to be sufficient for Ada to recognize and bind to the ada promoter. Furthermore, transactivation of the ada promoter by Ada C69H was enhanced up to 6-fold by treatment with methylating agents. An additional substitution was made with alanine in Ada C69H, replacing Cys321, the site for acceptance of a methyl group from O6-methylguanine and O4-methylthymine residues in DNA, with alanine. This renders the protein completely inactive as a methyltransferase but this derivative is constitutively active as a transactivator for the ada promoter. Therefore, acquisition of a methyl group at Cys321 apparently enhances the transactivating capacity of Ada protein on the ada promoter. We propose that the transcription-regulating function of Ada protein is under dual control by methylation of cysteine residues at positions 69 and 321; the former enhances DNA binding, while the latter enhances the transactivating capacity of the protein.

Amino Acid Sequence↗

PubMed1984

Regulation of prolactin secretion during suckling: involvement of the hypothalamo-pituitary GABAergic system.

Previous results demonstrated that GABA exerts a dual control on PRL secretion, one excitatory mediated in part by the impairment of the tubero-infundibular dopaminergic (TIDA) system function, the other inhibitory occurring at the level of the anterior pituitary (AP), where 3H-GABA and 3H-Muscimol (3H-M) recognition sites have been described. This report provides evidence for a physiological role of the tubero-infundibular GABAergic system (TI-GA-BA) on PRL secretion in the rat. In lactating rats separated for 4 h from their pups reinstitution of suckling for different periods resulted in an increase either in glutamic acid decarboxylase (GAD) activity in the mediobasal hypothalamus (MBH) or in AP-GABA content. Dynamic changes of the GABAergic function in the MBH-AP system seemed to have a certain degree of specificity because suckling did not affect GAD activity in the caudate nucleus. In lactating rats 2, 4, 8 and 24 h after removal of the offsprings AP-GABA concentrations and plasma PRL titers significantly decreased with respect to values present in rats never separated from their pups. Since it has been demonstrated that the PRL lowering effect of GABA is a receptor-mediated event, we have investigated the plasticity of AP-GABA receptors during suckling. The inhibitory action of GABA seems to be mediated mainly by the activation of the high affinity binding sites. This proposition is supported by the fact that in lactating rats, where only the high affinity receptor population is present, M was still able to decrease significantly plasma PRL concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Genetic basis of methicillin resistance in Staphylococcus aureus.

Methicillin resistance in staphylococci is due to the acquisition of the mecA gene encoding a new penicillin-binding protein (PBP2', PBP2a) that has a lower affinity to methicillin than the endogenous PBPs. PBP2' is involved in the assembly of the cell wall peptidoglycan in the presence of high concentrations of beta-lactams that otherwise inhibit the endogenous PBPs. The production of PBP2' is under dual control by its own mecR1-mecI- and the penicillinase blaR1-blaI-encoded regulatory elements. Resistance to high levels of methicillin depends, in addition to PBP2', on chromosomally encoded factors that are involved in the synthesis and degradation of the peptidoglycan. Any mutations that reduce peptidoglycan precursor formation or change the chemical composition of the muropeptide precursor result in lowered resistance.

Evolution, Molecular↗

PubMed1999

The rat suspension model is also a good tool for inducing muscle hyperactivity.

The aim of the present study was to investigate changes in the mechanical characteristics of the rat epitrochlearis muscle as a result of a period of hyperactivity. A tail suspension model was used to impose postural activity in the forelimb musculature with the intention of inducing a relative slowness in the fast epitrochlearis muscle. A method of dual-controlled releases was used to obtain force-velocity and tension-extension relationships characterizing muscle mechanics. Results showed that: (1) mechanical characteristics are that of a fast-twitch muscle and (2) suspension induces a decrease in the maximal shortening velocity and a decrease in the compliance of series elastic elements. Changes in fibre type proportions are consistent with these mechanical adaptations. This demonstrates that an usual model of muscle hypoactivity can also be used for imposing hyperactivity of a postural nature, inducing muscle transformations towards a slower twitch muscle.

Animals↗

PubMed2001

The stringent response, sigmaH-dependent gene expression and sporulation in Bacillus subtilis.

Recently, we found that transcription of the yvyD gene of Bacillus sibtilis from a sigmaH-dependent promoter is induced in response to amino acid starvation. This induction occurred in the wild type, but not in the relA mutant, suggesting that ppGpp might be involved in the activa tion of sigmaH. In order to substantiate this finding we looked for other sigmaH-dependent genes which also required an active relA gene product for activation in amino acid-starved cells. Three additional transcription units, namely spo0A, spoVG and the ytxGHI operon (also known as the csb40 operon), were found to be under the dual control of RelA and sigmaH in amino acid-starved cells, but many other sigmaH-dependent genes were not activated under these conditions. Of particular interest is the observation that spo0A is one of the genes that need a functional relA gene product for sigmaH-dependent gene activation. Furthermore, in sporulation medium, both Spo0A accumulation and phosphorylation are delayed in the relA deletion strain, leading to a delay in sporulation. A comparison between a relA point mutant and a relA deletion mutant revealed that the relA deletion mutant exhibits a more pronounced delay in the appearance of spores. These results suggest that the stringent response is not required for sporulation per se, but rather enhances the efficiency of sporulation.

Amino Acids↗

PubMed2006

The sexual excitation/sexual inhibition inventory for women: psychometric properties.

This article reports on the development of a new questionnaire designed to assess the propensity for sexual excitation and sexual inhibition in women: The Sexual Excitation/Sexual Inhibition Inventory for Women (SESII-W). The theoretical model underlying this research, the Dual Control Model, postulates that sexual response depends on a balance between excitatory and inhibitory mechanisms and that individuals vary in their propensity for excitation and inhibition. This study describes the development and initial validation of the SESII-W in a sample of 655 women (M age, 33.9 years). Factor analysis identified eight factors and two higher-order factors: one related to sexual excitation and one to sexual inhibition. The measure demonstrated good test-retest reliability and discriminant and convergent validity. Our data underscore that a number of factors affect women's sexual arousal and these appear to be related to opposing processes of sexual excitation and sexual inhibition. Theoretical issues, possible gender differences, and the value of using qualitative data to inform questionnaire development are discussed.

Adult↗

PubMed2006

Plus- and minus-stranded foot-and-mouth disease virus RNA quantified simultaneously using a novel real-time RT-PCR.

Even though tagged RT-PCR and rTth RT-PCR have been developed to improve strand-specific detection of RNA virus, these assays are not quantitative. In this study, a novel real-time RT-PCR assay, which combines the benefits of both the tagged and rTth RT-PCR has been developed to quantify the strand-specific RNA of foot-and-mouth disease virus (FMDV). The tagged-primers plus a TaqMan probe located within the highly conserved viral 3D region were used. The in vitro synthesized minus-and plus-stranded RNA templates were used as a dual control along with the copy number of viral RNA molecules, which is more reliable than reported RT-PCR employing a DNA-based standard. This assay was used to quantify FMDV RNA from 10(9) to 10(1) copies with a maximum sensitivity of between ten and five copies and was shown to be highly reproducible with low intra-and inter-assay variation. Coefficients of variation (CV) values were 0.70-1.39% and 0.98-2.1%, respectively. Importantly, the method was applied to simultaneously quantify both plus-stranded and minus-stranded FMDV RNA using tagged-RT and tagged-FP primer during a high-temperature reverse transcription. Highly sensitive and strand-specific real-time RT-PCR assay has been established. We tested the ratio of viral plus-stranded to minus-stranded RNA in acutely infected and persistently infected BHK-21 cells, for which the values ranged from 22/1 to 143/1 and from 287/1 to 334/1, respectively, suggesting different replication patterns of plus-and minus-stranded RNA in acutely infected and persistently infected cells. This value ranged from 83/1 to 93/1 in enriched FMDV virions, indicating that FMDV encapsidation is highly specific for plus-stranded RNAs. In addition, the method was applied to surveille the FMDV replication at animal level.

Animals↗

PubMed1988

Differential sensitivity of alpha o and alpha i to ADP-ribosylation by pertussis toxin in the intact cultured embryonic chick ventricular myocyte. Relationship to the role of G proteins in the coupling of muscarinic cholinergic receptors to inhibition of adenylate cyclase activity.

The guanine nucleotide regulatory proteins, alpha i and alpha o, coexist in a variety of tissues, including heart, brain, and adipose tissues and are ADP-ribosylated by pertussis toxin (Gilman AG, G-proteins and dual control of adenylate cyclase. Cell 26: 577-579, 1984). Previous studies in which purified G proteins were reconstituted with cell membranes and/or phospholipid vesicles have suggested that an alpha i-like protein mediates GTP-dependent inhibition of adenylate cyclase activity. However, direct studies comparing the role of alpha i and alpha o in mediating the inhibition of adenylate cyclase activity in the intact cell have not appeared. In the present study, we demonstrated that, in the intact cell, alpha o was more sensitive to ADP-ribosylation in the presence of pertussis toxin than was alpha i. The T1/2 for pertussis toxin-mediated ADP-ribosylation of alpha i was 199 +/- 10 min (mean +/- SE, N = 10) compared to 157 +/- 7 min for alpha o. The IC50 for pertussis toxin-induced ADP-ribosylation of alpha i was 158 +/- 40 pg/ml (mean +/- SE, N = 11) compared to 35 +/- 8 pg/ml for alpha o. The differences in both T1/2 and IC50 for alpha i and alpha o were statistically significant (P less than 0.001). Studies were carried out to determine whether alpha o was involved in coupling the muscarinic cholinergic receptor to inhibition of adenylate cyclase activity in intact cells. The time course and dose dependence of the pertussis toxin-induced uncoupling of the muscarinic receptor from inhibition of adenylate cyclase closely paralleled the time course and dose dependence for the ADP-ribosylation of alpha i but differed significantly (P less than 0.001) from the time course and dose dependence for the ADP-ribosylation of alpha i but differed significantly (P less than 0.001) from the time course and dose dependence of the pertussis toxin mediated ADP-ribosylation of alpha o. The T1/2 and IC50 values for the pertussis toxin-induced decrease in the inhibition of adenylate cyclase activity were 210 +/- 6 min (mean +/- SE, N = 11) and 169 +/- 25 pg/ml (mean +/- SE, N = 12), respectively, which were not significantly different from the T1/2 and IC50 for pertussis toxin mediated ADP-ribosylation of alpha i. The data are consistent with the hypothesis that, in the intact cell, a pertussis toxin-sensitive alpha i-like protein, but not alpha o, couples muscarinic receptors to inhibition of adenylate cyclase activity.

Adenosine Diphosphate Ribose↗

PubMed1988

Evidence for involvement of an adrenal catecholamine in the beta-adrenergic inhibition of oxytocin release in lactating rats.

Adrenergic systems exert dual control over the release of oxytocin (OT) in rats, with stimulation of alpha-adrenergic receptors exciting, and stimulation of beta-adrenergic receptors inhibiting, release of this neurohormone. Because suckling stimulation also releases epinephrine from the adrenal medulla, the present experiments tested whether catecholamines of adrenal origin may participate in the adrenergic regulation of OT release during lactation. In two independent experiments, adrenal demedullation of rats in midlactation did not alter the basal plasma levels of OT, but markedly enhanced the suckling-induced release of OT, suggesting an inhibitory action of an adrenal catecholamine. The OT release induced by suckling in both sham-operated and adrenal demedullated rats was prevented by stimulation of beta-adrenergic receptors with isoproterenol. Conversely, blockade of beta-adrenergic receptors with propranolol prevented the inhibitory effects of isoproterenol, and when given alone, mimicked the effects of demedullation to enhance suckling-induced OT release. Stimulation of peripheral alpha-adrenergic receptors with phenylephrine did not affect either basal or suckling-induced OT release, but blockade of alpha-adrenergic receptors with phentolamine also completely prevented the release of OT by suckling. These data support the concept that stimulation of beta-adrenergic receptors inhibits OT secretion, and further suggest that this may be due, at least in part, to an action of an adrenal catecholamine, which may act centrally and/or directly on the neurohypophysis. The present results also provide further evidence that activation of central, but not peripheral, alpha-adrenergic mechanisms is necessary for suckling-induced OT release.

Adrenal Medulla↗