scholarly journals Inhibition of ovarian steroidogenesis by cyclic GMP in a fly

2003 ◽  
Vol 177 (1) ◽  
pp. 35-44 ◽  
Author(s):  
G Maniere ◽  
E Vanhems ◽  
F Gautron ◽  
JP Delbecque
Keyword(s):  
Close Correlation ◽  
Negative Control ◽  
Phormia Regina ◽  
No Donor ◽  
Ovarian Steroidogenesis ◽  
Cgmp Analog ◽  
Ecdysteroid Biosynthesis ◽  
Negative Effect ◽  
First Time

Previous investigations in the female blowfly Phormia regina have shown that 3-isobutyl-1-methylxanthine (IBMX), a broad spectrum inhibitor of phosphodiesterases (PDEs), fails to mimic the steroidogenic effects of cAMP on ovaries, although it efficiently increases the concentrations of this second messenger. In this study, experiments carried out to clear up this contradiction demonstrated that IBMX, besides its effect on cAMP, also increased cGMP concentrations in blowfly ovary and that these two cyclic nucleotides controlled ovarian steroidogenesis antagonistically. In particular, a selective inhibitor of cGMP-specific PDEs, unlike IBMX, had a very strong negative effect on ovarian steroidogenesis. Moreover, a cGMP analog was able to inhibit steroid biosynthesis in previtellogenic and vitellogenic ovaries, thus affecting basal and acute steroidogenesis respectively. Our observations also demonstrated that cGMP was always present in blowfly ovary, reaching its maximal levels at the end of vitellogenesis, in close correlation with the physiological decrease in ovarian steroidogenesis. Experiments using an inhibitor of protein kinase G clearly indicated that the effects of cGMP were mediated by this enzyme. On the contrary, these effects did not seem to involve cGMP-regulated PDEs or ion channels. Our results also indicated that ovarian cGMP concentrations were not controlled by brain factors, suggesting a probable involvement of paracrine/autocrine factors. Nitric oxide (NO) appeared to be a good candidate for such a control, because an NO donor was able to stimulate ovarian cGMP concentrations and to drastically decrease ovarian ecdysteroid biosynthesis in blowflies. These data thus demonstrate, for the first time in invertebrates, a potent role of cGMP in the negative control of ovarian steroidogenesis and suggest a possible co-regulation with NO.

Insurance regulations, risk and performance in Ghana

2019 ◽  
Vol 28 (1) ◽  
pp. 74-96
Author(s):  
Baah Aye Kusi ◽  
Abdul Latif Alhassan ◽  
Daniel Ofori-Sasu ◽  
Rockson Sai
Keyword(s):  
Random Effect ◽  
Least Square ◽  
Insurance Market ◽  
Content Type ◽  
Ordinary Least Square ◽  
Negative Effect ◽  
And Performance ◽  
First Time

Purpose This study aims to examine the hypothesis that the effect of insurer risks on profitability is conditional on regulation, using two main regulatory directives in the Ghanaian insurance market as a case study. Design/methodology/approach This study used the robust ordinary least square and random effect techniques in a panel data of 30 insurers from 2009 to 2015 to test the research hypothesis. Findings The results suggest that regulations on no credit premium and required capital have insignificant effects on profitability of insurers. On the contrary, this study documents evidence that both policies mitigate the effect of underwriting risk on profitability and suggests that regulations significantly mitigate the negative effect of underwriting risk to improve profitability. Practical implications The finding suggests that policymakers and regulators must continue to initiate, design and model regulations such that they help tame risk to improve the performance of insurers in Ghana. Originality/value This study provides first-time evidence on the role of regulations in controlling risks in a developing insurance market.

scholarly journals The Effects of Corporate Bonds on Employment: Early Evidence from Greece

2020 ◽  
Vol 12 (2) ◽  
pp. 235-253
Author(s):  
Sotirios Karagiannis ◽  
Dimitrios Thomakos
Keyword(s):  
Corporate Bonds ◽  
Banking System ◽  
External Financing ◽  
Listed Firms ◽  
Negative Effect ◽  
The Impact ◽  
First Time ◽  
Investment Choices ◽  
Positive Effect

This study investigates the impact of corporate bonds issued by Greek listed firms on employment. Even though external financing and the effects on employment has been studied in the literature, we extend the existing literature by focusing for the first time on the specific role of corporate bonds on employment. We have collected all the relevant papers on this line of the literature and concisely report them in a table format and then use them in analyzing our results. Our empirical analysis is based on a panel dataset from 2001 to 2014 and we examine the effect of corporate bonds in the pre and post period of the Greek economic crisis, in which the banking system is vulnerable and unable to provide financing to the firms. The results suggest that corporate bonds have a positive effect on employment in the pre-crisis sample, denoting that firms hire employees and proceed to investment choices. On the contrary, during the recession, corporate bonds have a negative effect on employment. Firms reduce their costs and try to control their debt obligations by issuing corporate bonds.

scholarly journals Pesticide Residues and Stuck Fermentation in Wine: New Evidences Indicate the Urgent Need of Tailored Regulations

Fermentation ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 23 ◽  
Author(s):  
Pasquale Russo ◽  
Carmen Berbegal ◽  
Cristina De Ceglie ◽  
Francesco Grieco ◽  
Giuseppe Spano ◽  
...  
Keyword(s):  
Microbial Growth ◽  
Culture Media ◽  
Candida Spp ◽  
Inhibitory Spectrum ◽  
Negative Effect ◽  
Screening Procedures ◽  
Moderately Resistant ◽  
First Time ◽  
Commercial Fungicide

For three consecutive years, an Italian winery in Apulia has dealt with sudden alcoholic stuck fermentation in the early stages of vinification process, i.e., typical defects addressable to bacterial spoilage. After a prescreening trial, we assessed, for the first time, the influence of the commercial fungicide preparation Ridomil Gold® (Combi Pepite), containing Metalaxyl-M (4.85%) and Folpet (40%) as active principles, on the growth of several yeasts (Saccharomyces cerevisiae and non-Saccharomyces spp.) and lactic acid bacteria of oenological interest. We also tested, separately and in combination, the effects of Metalaxyl-M and Folpet molecules on microbial growth both in culture media and in grape must. We recalled the attention on Folpet negative effect on yeasts, extending its inhibitory spectrum on non-Saccharomyces (e.g., Candida spp.). Moreover, we highlighted a synergic effect of Metalaxyl-M and Folpet used together and a possible inhibitory role of the fungicide excipients. Interestingly, we identified the autochthonous S. cerevisiae strain E4 as moderately resistant to the Folpet toxicity. Our findings clearly indicate the urgent need for integrating the screening procedures for admission of pesticides for use on wine grape with trials testing their effects on the physiology of protechnological microbes.

scholarly journals Intercultural Mobility and European Identity: Impact of the Erasmus Exchange Programme in Terms of Cultural Differences

2020 ◽  
Vol 13 (1) ◽  
pp. 77-94
Author(s):  
Fatih Goksu
Keyword(s):  
National Identity ◽  
Cultural Differences ◽  
Positive Impact ◽  
European Identity ◽  
Structured Interviews ◽  
Semistructured Interviews ◽  
Negative Effect ◽  
Exchange Programme ◽  
First Time

European mobility programmes have been seen as a promising method to promote European identity, particularly with a focus on young generations. In this article, I discussed the constructing role of the Erasmus exchange programme by employing the result of direct crosscultural interaction. Data from Eurobarometer surveys and outcomes concluded from the semistructured interviews revealed that socialising with other Europeans strengthened European identity but contact with the host country remained limited. Diff erent from other studies, this paper also reveals that the national identity of the participants precisely empower as a result of coaction. Furthermore, for the first time in the literature, semi-structured interviews unveiled that cultural differences such as stereotypes and prejudices have no negative effect in promoting European identity among students. Rather, it generates a positive impact for the awareness of national identity.

scholarly journals Citrate Inhibition-Resistant Form of 6-Phosphofructo-1-Kinase from Aspergillus niger

2006 ◽  
Vol 72 (7) ◽  
pp. 4515-4521 ◽  
Author(s):  
Tina Mlakar ◽  
Matic Legiša
Keyword(s):  
Aspergillus Niger ◽  
Posttranslational Modification ◽  
Binding Sites ◽  
Positive Control ◽  
Negative Control ◽  
Negative Effect ◽  
Flow Through ◽  
First Time ◽  
Citrate Inhibition

ABSTRACT Two forms of Aspergillus niger 6-phosphofructo-1-kinase (PFK1) have been described recently, the 85-kDa native enzyme and 49-kDa shorter fragment that is formed from the former by posttranslational modification. So far, kinetic characteristics have never been determined on the enzyme purified to near homogeneity. For the first time, kinetic parameters were determined for individual enzymes with respect to citrate inhibition. The native 85-kDa enzyme was found to be moderately inhibited by citrate, with the Ki value determined to be 1.5 mM, in the system with 5 mM Mg2+ ions, while increasing magnesium concentrations relieved the negative effect of citrate. An identical inhibition coefficient was determined also in the presence of ammonium ions, although ammonium acted as a strong activator of enzyme activity. On the other hand, the shorter fragment of PFK1 proved to be completely resistant to inhibition by citrate. Allosteric citrate binding sites were most probably lost after the truncation of the C-terminal part of the native protein, in which region some binding sites for inhibitor are known to be located. At near physiological conditions, characterized by low fructose-6-phosphate concentrations, a much higher efficiency of the shorter fragment was observed during an in vitro experiment. Since the enzyme became more susceptible to the positive control by specific ligands, while the negative control was lost after posttranslational modification, the shorter PFK1 fragment seems to be the enzyme most responsible for generating undisturbed metabolic flow through glycolysis in A. niger cells.

scholarly journals The Possible Role of the Nitroso-Sulfide Signaling Pathway in the Vasomotoric Effect of Garlic Juice

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 590 ◽  
Author(s):  
Andrea Berenyiova ◽  
Marian Grman ◽  
Anton Misak ◽  
Samuel Golas ◽  
Justina Cuchorova ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Soluble Guanylyl Cyclase ◽  
Cardiovascular Effects ◽  
Bioactive Compound ◽  
Isometric Tension ◽  
No Donor ◽  
Organic Sulfides ◽  
Relaxant Response ◽  
First Time

The beneficial cardiovascular effects of garlic have been reported in numerous studies. The major bioactive properties of garlic are related to organic sulfides. This study aimed to investigate whether garlic juice works exclusively due to its sulfur compounds or rather via the formation of new products of the nitroso-sulfide signaling pathway. Changes in isometric tension were measured on the precontracted aortic rings of adult normotensive Wistar rats. We evaluated NO-donor (S-nitrosoglutathione, GSNO)-induced vasorelaxation and compare it with effects of hydrogen sulfide (H2S)/GSNO and garlic/GSNO. Incubation with garlic juice increased the maximal GSNO-induced relaxation and markedly changed the character of the relaxant response. Although incubation with an H2S donor enhanced the maximal vasorelaxant response of GSNO, neither the absolute nor the relative relaxation changed over time. The mixture of GSNO with an H2S donor evoked a response similar to GSNO-induced relaxation after incubation with garlic juice. This relaxation of the H2S and GSNO mixture was soluble guanylyl cyclase (sGC) dependent, partially reduced by HNO scavenger and it was adenosine triphosphate-sensitive potassium channels (KATP) independent. In this study, we demonstrate for the first time the suggestion that H2S itself is probably not the crucial bioactive compound of garlic juice but rather potentiates the production of new signaling molecules during the GSNO-H2S interaction.

The permissive role of endothelial NO in CO-induced cerebrovascular dilation

2004 ◽  
Vol 287 (4) ◽  
pp. H1459-H1465 ◽  
Author(s):  
Ebrahim Barkoudah ◽  
Jonathan H. Jaggar ◽  
Charles W. Leffler
Keyword(s):  
Guanylyl Cyclase ◽  
Constant Concentration ◽  
No Donor ◽  
Tetraethylammonium Chloride ◽  
Dimanganese Decacarbonyl ◽  
Cgmp Analog ◽  
Pial Arterioles ◽  
Permissive Role ◽  
Intravascular Pressure

Carbon monoxide (CO) and nitric oxide (NO) are important paracrine messengers in the newborn cerebrovasculature that may act as comessengers. Here, we investigated the role of NO in CO-mediated dilations in the newborn cerebrovasculature. Arteriolar branches of the middle cerebral artery (100–200 μm) were isolated from 3- to 7-day-old piglets and cannulated at each end in a superfusion chamber, and intravascular pressure was elevated to 30 mmHg, which resulted in the development of myogenic tone. Endothelium removal abolished dilations of pressurized pial arterioles to bradykinin and to the CO-releasing molecule Mn2(CO)10 [dimanganese decacarbonyl (DMDC)] but not dilations to isoproterenol. With endothelium intact, Nω-nitro-l-arginine (l-NNA), 1 H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), or tetraethylammonium chloride (TEA+), inhibitors of NO synthase (NOS), guanylyl cyclase, and large-conductance Ca2+-activated K+ (KCa) channels, respectively, also blocked dilation induced by DMDC. After inhibition of NOS, a constant concentration of sodium nitroprusside (SNP), a NO donor that only dilated the vessel 6%, returned dilation to DMDC. The stable cGMP analog 8-bromo-cGMP also restored dilation to DMDC in endothelium-intact, l-NNA-treated, or endothelium-denuded arterioles, and this effect was blocked by TEA+. Similarly, in the continued presence of ODQ, 8-bromo-cGMP restored DMDC-induced dilations. These findings suggest that endothelium-derived NO stimulates guanylyl cyclase in vascular smooth muscle cells and, thereby, permits CO to cause dilation by activating KCa channels. Such a requirement for NO could explain the endothelium dependency of CO-induced dilation in piglet pial arterioles.

scholarly journals Downregulation of Soluble Guanylate Cyclase and Protein Kinase G With Upregulated ROCK2 in the Pulmonary Artery Leads to Thromboxane A2 Sensitization in Monocrotaline-Induced Pulmonary Hypertensive Rats

2021 ◽  
Vol 12 ◽  
Author(s):  
Suhan Cho ◽  
Hyun Namgoong ◽  
Hae Jin Kim ◽  
Rany Vorn ◽  
Hae Young Yoo ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Thromboxane A2 ◽  
Immunoblot Analysis ◽  
No Donor ◽  
Cgmp Signaling ◽  
Cgmp Analog ◽  
Pulmonary Arterial

Thromboxane A2 (TXA2) promotes various physiological responses including pulmonary artery (PA) contraction, and pathophysiological implications have been suggested in cardiovascular diseases including pulmonary hypertension. Here, we investigated the role of TXA2 receptor (TP)-mediated signaling in the pathophysiology of pulmonary arterial hypertension (PAH). The sensitivity of PA to the contractile agonist could be set by relaxing signals such as the nitric oxide (NO), soluble guanylate cyclase (sGC), and cGMP-dependent kinase (PKG) pathways. Changes in the TP agonist (U46619)-induced PA contraction and its modulation by NO/cGMP signaling were analyzed in a monocrotaline-induced PAH rat model (PAH-MCT). In the myograph study, PA from PAH-MCT showed higher responsiveness to U46619, that is decreased EC50. Immunoblot analysis revealed a lower expression of eNOS, sGC, and PKG, while there was a higher expression of RhoA-dependent kinase 2 (ROCK2) in the PA from PAH-MCT than in the control. In PAH-MCT, the higher sensitivity to U46619 was reversed by 8-Br-cGMP, a membrane-permeable cGMP analog, but not by the NO donor, sodium nitroprusside (SNP 30 μM). In contrast, in the control PA, inhibition of sGC by its inhibitor (1H− [1,2,4] oxadiazolo [4,3−a] quinoxalin-1-one (ODQ), 10 μM) lowered the threshold of U46619-induced contraction. In the presence of ODQ, SNP treatment had no effect whereas the addition of 8-Br-cGMP lowered the sensitivity to U46619. The inhibition of ROCK by Y-27632 attenuated the sensitivity to U46619 in both control and PAH-MCT. The study suggests that the attenuation of NO/cGMP signaling and the upregulation of ROCK2 increase the sensitivity to TXA2 in the PAH animal, which might have pathophysiological implications in patients with PAH.

Social Motives Predict Loneliness During a Developmental Transition

2017 ◽  
Vol 76 (4) ◽  
pp. 145-153 ◽  
Author(s):  
Jana Nikitin ◽  
Alexandra M. Freund
Keyword(s):  
Social Relationships ◽  
Well Being ◽  
Social Avoidance ◽  
Social Approach ◽  
Social Motives ◽  
Developmental Transitions ◽  
Avoidance Motivation ◽  
Negative Effect ◽  
Low Levels

Abstract. Establishing new social relationships is important for mastering developmental transitions in young adulthood. In a 2-year longitudinal study with four measurement occasions (T1: n = 245, T2: n = 96, T3: n = 103, T4: n = 85), we investigated the role of social motives in college students’ mastery of the transition of moving out of the parental home, using loneliness as an indicator of poor adjustment to the transition. Students with strong social approach motivation reported stable and low levels of loneliness. In contrast, students with strong social avoidance motivation reported high levels of loneliness. However, this effect dissipated relatively quickly as most of the young adults adapted to the transition over a period of several weeks. The present study also provides evidence for an interaction between social approach and social avoidance motives: Social approach motives buffered the negative effect on social well-being of social avoidance motives. These results illustrate the importance of social approach and social avoidance motives and their interplay during developmental transitions.

Psychological Resilience Provides No Independent Protection From Suicidal Risk

Crisis ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Danica W. Y. Liu ◽  
A. Kate Fairweather-Schmidt ◽  
Richard Burns ◽  
Rachel M. Roberts ◽  
Kaarin J. Anstey
Keyword(s):  
Risk Factors ◽  
Well Being ◽  
Current Status ◽  
Psychological Resilience ◽  
Cross Sectional ◽  
Life Project ◽  
Resilience Factors ◽  
First Time

Abstract. Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.

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