33 research outputs found
Recommended from our members
Chronic treatment with Carvedilol improves ventricular function and reduces myocyte apoptosis in an animal model of heart failure
BACKGROUND: ÎČ-blocker treatment has emerged as an effective treatment modality for heart failure. Interestingly, ÎČ-blockers can activate both pro-apoptotic and anti-apoptotic pathways. Nevertheless, the mechanism for improved cardiac function seen with ÎČ-blocker treatment remains largely unknown. Carvedilol is a non-selective ÎČ-blocker with α-receptor blockade and antioxidant properties. We therefore studied the impact of the effects of carvedilol in an animal model of end-stage heart failure. RESULTS: To test whether chronic treatment with ÎČ-blockade decreases apoptosis, we treated myopathic turkeys with two dosages of carvedilol, 1 mg/kg (DCM(1)) and 20 mg/kg (DCM(20)), for four weeks and compared them to non-treated DCM animals (DCM(0)) and to control turkeys (CON). Echocardiographic measurements showed that non-treated DCM animals had a significantly lower fractional shortening (FS) when compared to CON (68.73 ± 1.37 vs. 18.76 ± 0.59%, p < 0.001). Both doses of carvedilol significantly improved FS (33.83 ± 10.11 and 27.73 ± 6.18% vs. 18.76 ± 0.59 % for untreated DCM, p < 0.001). DCM left ventricles were characterized by a higher percentage of apoptotic nuclei when compared to CON (5.64 ± 0.49 vs. 1.72 ± 0.12%, respectively p < 0.001). Both doses of carvedilol significantly reduced the number of apoptotic nuclei (2.32 ± 0.23% and 2.36 ± 0.26% 1 mg and 20 mg/kg respectively). CONCLUSIONS: Carvedilol improves ventricular function. Furthermore, treatment with carvedilol decreased the incidence of apoptosis in cardiac myocytes from failing hearts at both doses. These data suggest that the inhibition of apoptosis with carvedilol may lead to improvement in ventricular function and may underlie a beneficial effect of ÎČ-blockade independent of heart rate lowering effects
The use of passive seismological imaging in speleogenetic studies: an example from Kanaan Cave, Lebanon
Among many parameters that control the evolution of caves stands the volume of unconsolidated clay sediments generally produced by the alteration of the calcareous rocks. Here we introduce the use of a passive seismological imaging technique to investigate the clay deposits and estimate its total volume in a cave. Applied for the first time for speleogenesis studies, the HVSR (Horizontal / Vertical Spectral Ration) is a geophysical technique that can help better interpret cave geomorphology. We apply seismological spectral techniques (H/V ratio) on ambient noise vibrations to derive the clay volume, as well as its shape. This technique applied on the clay volume reveals some internal details, such as fallen blocks prior to the deposit accumulation and helps to understand deposit evacuation dynamics. The study focuses on the Kanaan Cave, located in Metn District, Lebanon, and reveals new stages related to the cave speleogenesis. This technique could be applied on âparageneticâ caves where clay volume is frequently present in order to constrain the clay volume and reconstruct the buried floor shape of the cave, underneath the clay deposit
Bcl11a is essential for lymphoid development and negatively regulates p53
Transcription factors play important roles in lymphopoiesis. We have previously demonstrated that Bcl11a is essential for normal lymphocyte development in the mouse embryo. We report here that, in the adult mouse, Bcl11a is expressed in most hematopoietic cells and is highly enriched in B cells, early T cell progenitors, common lymphoid progenitors (CLPs), and hematopoietic stem cells (HSCs). In the adult mouse, Bcl11a deletion causes apoptosis in early B cells and CLPs and completely abolishes the lymphoid development potential of HSCs to B, T, and NK cells. Myeloid development, in contrast, is not obviously affected by the loss of Bcl11a. Bcl11a regulates expression of Bcl2, Bcl2-xL, and Mdm2, which inhibits p53 activities. Overexpression of Bcl2 and Mdm2, or p53 deficiency, rescues both lethality and proliferative defects in Bcl11a-deficient early B cells and enables the mutant CLPs to differentiate to lymphocytes. Bcl11a is therefore essential for lymphopoiesis and negatively regulates p53 activities. Deletion of Bcl11a may represent a new approach for generating a mouse model that completely lacks an adaptive immune system
Caractérisation des ARN régulateurs dépendants du systÚme à deux composants CiaRH chez Streptococcus agalactiae
International audienceStreptococcus agalactiae st la premiĂšre cause dâinfections nĂ©onatales humaines. Cette bactĂ©rie sâadapte Ă son environnement en modulant lâexpression de ses gĂšnes grĂące aux ARN rĂ©gulateurs pouvant eux mĂȘmes ĂȘtre rĂ©gulĂ©s par des systĂšmes Ă deux composants (TCS). Chez S. agalactiae, quatre ARN rĂ©gulateurs potentiellement dĂ©pendants du TCS CiaRH ont prĂ©cĂ©demment Ă©tĂ© identifiĂ©s par RNAseq : Srn015, Srn024, Srn070 et Srn085. Les objectifs sont de dĂ©montrer lâimplication de CiaRH dans lâexpression de ces ARN, dâidentifier une cible et la fonction biologique de Srn024. Cette Ă©tude a mis en Ă©vidence une rĂ©gulation positive des quatre ARN par CiaRH et lâimportance de la sĂ©quence promotrice TTTAAG-5N-TTTAAG dans la rĂ©gulation de Srn024. Une analyse in silico a rĂ©vĂ©lĂ© une similaritĂ© de sĂ©quence entre Srn024 et lâARNm sap, codant une pullulanase. Cette Ă©tude a dĂ©montrĂ© une rĂ©gulation nĂ©gative de cette cible par Srn024. La protĂ©ine Sap est connue pour ĂȘtre impliquĂ©e dans la dĂ©gradation des α-glucanes tel que le pullulane et dans la liaison aux cellules Ă©pithĂ©liales cervicales humaines. Le mutant dâinactivation du gĂšne sap empĂȘche la croissance de S. agalactiae dans un milieu contenant comme seule source nutritive du pullulane. Ce mutant produit Ă©galement moins de biofilm que la souche sauvage. Les mutants de dĂ©lĂ©tion des gĂšnes srn024 et ciaRH prĂ©sentent une meilleure croissance en prĂ©sence de pullulane et produisent plus de biofilm que la souche sauvage. Ces rĂ©sultats suggĂšrent lâimplication de Srn024 dans lâadaptation de S. agalactiae aux changements environnementaux et la formation de biofilm grĂące Ă la rĂ©gulation du gĂšne sap
An Inventory of CiaR-Dependent Small Regulatory RNAs in Streptococci
International audienceBacteria adapt to the different environments encountered by rapid and tightly controlled regulations involving complex networks. A first line of control is transcriptional with regulators such as two-component systems (TCSs) that respond to physical and chemical perturbations. It is followed by posttranscriptional regulations in which small regulatory RNAs (sRNAs) may affect RNA translation. Streptococci are opportunistic pathogens for humans and farm animals. The TCS CiaRH is highly conserved among this genus and crucial in bacterial survival under stressful conditions. In several streptococcal species, some sRNAs belong to the CiaRH regulon and are called csRNAs for cia-dependent sRNAs. In this review, we start by focusing on the Streptococcus species harboring a CiaRH TCS. Then the role of CiaRH in streptococcal pathogenesis is discussed in the context of recent studies. Finally, we give an overview of csRNAs and their functions in Streptococci with a focus on their importance in bacterial adaptation and virulence
Srn024, un petit ARN nécessaire à la croissance bactérienne chez le pathogÚne <em>Streptococcus agalactiae</em>
National audienceIntroduction et objectif : Streptococcus agalactie est la cause majeure des infections nĂ©onatales humaines, mais aussi un pathogĂšne Ă©mergent chez les adultes immunodĂ©primĂ©s. Sa capacitĂ© Ă coloniser diffĂ©rents hĂŽtes montre son aptitude Ă sâadapter aux changements environnementaux, qui serait en partie due aux ARN rĂ©gulateurs, trĂšs peu Ă©tudiĂ©s chez S. agalactie. LâARN potentiellement rĂ©gulateur Srn024 a Ă©tĂ© identifiĂ© par RNAseq mais sa fonction reste inconnue. Par ailleurs, il serait rĂ©gulĂ© par le systĂšme Ă deux composants CiaRH, qui semble impliquĂ© dans diffĂ©rents processus tels que la formation de biofilm et lâantibiorĂ©sistance. Lâobjectif ici est dâidentifier la fonction de Srn024 afin de mieux comprendre les rĂ©seaux de rĂ©gulation bactĂ©riens sous le contrĂŽle des ARN. MatĂ©riels et mĂ©thodes : La prĂ©valence du gĂšne srn024, identifiĂ© dans la souche S. agalactiae NEM316, premiĂšre souche sĂ©quencĂ©e, a Ă©tĂ© Ă©tudiĂ©e dans 374 souches reprĂ©sentatives de la diversitĂ© gĂ©nĂ©tique de lâespĂšce en utilisant des techniques de biologie molĂ©culaire et des analyses in silico de gĂ©nomes sĂ©quencĂ©s. Puis, un mutant de dĂ©lĂ©tion de srn024 a Ă©tĂ© construit dans la souche NEM316. DiffĂ©rents phĂ©notypes liĂ©s Ă CiaRH ont Ă©tĂ© recherchĂ©s dans la souche mutante : la formation de biofilm, la sensibilitĂ© aux antibiotiques et la croissance bactĂ©rienne. RĂ©sultats, discussion et conclusion : Srn024 est prĂ©sent chez toutes les souches quelle que soit leur origine anatomique ou leur position phylogĂ©nĂ©tique. Le rĂŽle biologique de Srn024 a Ă©tĂ© Ă©tudiĂ© en construisant un mutant NEM316âsrn024. Les concentrations minimales inhibitrices des diffĂ©rents antibiotiques testĂ©s sont identiques pour la souche sauvage et NEM316âsrn024. La formation du biofilm semble Ă©galement similaire pour les deux souches. En revanche, un dĂ©faut de croissance de la souche mutante par rapport Ă la souche sauvage a Ă©tĂ© mis en Ă©vidence en milieu chimiquement dĂ©fini (MCD) alors que ces deux souches ont une croissance identique en milieu Todd-Hewitt. Ces rĂ©sultats semblent indiquer que lâARN rĂ©gulateur Srn024 permettrait Ă la bactĂ©rie de sâadapter en MCD. Des expĂ©riences de complĂ©mentation du phĂ©notype de la souche mutante sont indispensables pour confirmer ces rĂ©sultats. Des analyses plus poussĂ©es seront nĂ©cessaires pour comprendre le mĂ©canisme dâadaptation de ce mutant Ă ce milieu
Biofilm Formation in Streptococcus agalactiae Is Inhibited by a Small Regulatory RNA Regulated by the Two-Component System CiaRH
International audienceRegulatory small RNAs (sRNAs) are involved in the adaptation of bacteria to their environment. CiaR-dependent sRNAs (csRNAs) are controlled by the regulatory twocomponent system (TCS) CiaRH, which is widely conserved in streptococci. Except for Streptococcus pneumoniae and Streptococcus sanguinis, the targets of these csRNAs have not yet been investigated. Streptococcus agalactiae, the leading cause of neonatal infections, has four conserved csRNA genes, namely, srn015, srn024, srn070, and srn085. Here, we demonstrate the importance of the direct repeat TTTAAG-N5-TTTAAG in the regulation of these csRNAs by CiaRH. A 24-nucleotide Srn024-sap RNA base-pairing region is predicted in silico. The sap gene encodes a LPXTG-cell wall-anchored pullulanase. This protein cleaves a-glucan polysaccharides such as pullulan and glycogen present in the environment to release glucose and is involved in adhesion to human cervical epithelial cells. Inactivation of S. agalactiae pullulanase (SAP) leads to no bacterial growth in a medium with only pullulan as a carbon source and reduced biofilm formation, while deletion of ciaRH and srn024 genes significantly increases bacterial growth and biofilm formation. Using a new translational fusion vector, we demonstrated that Srn024 is involved in the posttranscriptional regulation of sap expression. Complementary base pair exchanges in S. agalactiae suggest that Srn024 interacts directly with sap mRNA and that disruption of this RNA pairing is sufficient to yield the biofilm phenotype of Srn024 deletion. These results suggest the involvement of Srn024 in the adaptation of S. agalactiae to environmental changes and biofilm formation, likely through the regulation of the sap gene. IMPORTANCE Although Streptococcus agalactiae is a commensal bacterium of the human digestive and genitourinary tracts, it is also an opportunistic pathogen for humans and other animals. As the main cause of neonatal infections, it is responsible for pneumonia, bacteremia, and meningitis. However, its adaptation to these different ecological niches is not fully understood. Bacterial regulatory networks are involved in this adaptation, and the regulatory TCSs (e.g., CiaRH), as well as the regulatory sRNAs, are part of it. This study is the first step to understand the role of csRNAs in the adaptation of S. agalactiae. This bacterium does not currently exhibit extensive antibiotic resistance. However, it is crucial to find alternatives before multidrug resistance emerges. Therefore, we propose that drugs targeting regulatory RNAs with Srn024-like activities would affect pathogens by reducing their abilities to form biofilm and to adapt to host niches
Srn024, un petit ARN nécessaire à la croissance bactérienne chez le pathogÚne Streptococcus agalactiae
poster + "pitch" de 90 secondes de prĂ©sentation du posterStreptococcus agalactie est la cause majeure des infections nĂ©onatales humaines, mais aussi un pathogĂšne Ă©mergent chez les adultes immunodĂ©primĂ©s. Sa capacitĂ© Ă coloniser diffĂ©rents hĂŽtes montre son aptitude Ă sâadapter aux changements environnementaux, qui serait en partie due aux ARN rĂ©gulateurs, trĂšs peu Ă©tudiĂ©s chez S. agalactie. LâARN potentiellement rĂ©gulateur Srn024 a Ă©tĂ© identifiĂ© par RNAseq mais sa fonction reste inconnue [1]. Par ailleurs, il serait rĂ©gulĂ© par le systĂšme Ă deux composants CiaRH, qui semble impliquĂ© dans diffĂ©rents processus tels que la formation de biofilm et lâantibiorĂ©sistance [2]. Lâobjectif ici est dâidentifier la fonction de Srn024 afin de mieux comprendre les rĂ©seaux de rĂ©gulation bactĂ©riens sous le contrĂŽle des ARN.La prĂ©valence du gĂšne srn024, identifiĂ© dans la souche S. agalactiae NEM316, premiĂšre souche sĂ©quencĂ©e, a Ă©tĂ© Ă©tudiĂ©e dans 374 souches reprĂ©sentatives de la diversitĂ© gĂ©nĂ©tique de lâespĂšce en utilisant des techniques de biologie molĂ©culaire et des analyses in silico de gĂ©nomes sĂ©quencĂ©s. Puis, un mutant de dĂ©lĂ©tion de srn024 a Ă©tĂ© construit dans la souche NEM316. DiffĂ©rents phĂ©notypes liĂ©s Ă CiaRH ont Ă©tĂ© recherchĂ©s dans la souche mutante : la formation de biofilm, la sensibilitĂ© aux antibiotiques et la croissance bactĂ©rienne.Srn024 est prĂ©sent chez toutes les souches quelle que soit leur origine anatomique ou leur position phylogĂ©nĂ©tique. Le rĂŽle biologique de Srn024 a Ă©tĂ© Ă©tudiĂ© en construisant un mutant NEM316Îsrn024. Les concentrations minimales inhibitrices des diffĂ©rents antibiotiques testĂ©s sont identiques pour la souche sauvage et NEM316Îsrn024. La formation du biofilm semble Ă©galement similaire pour les deux souches. En revanche, un retard de croissance de la souche mutante par rapport Ă la souche sauvage a Ă©tĂ© mis en Ă©vidence en milieu chimiquement dĂ©fini (MCD) alors que ces deux souches ont une croissance identique en milieu Todd-Hewitt. Ces rĂ©sultats semblent indiquer que lâARN rĂ©gulateur Srn024 permettrait Ă la bactĂ©rie de sâadapter en MCD. Des expĂ©riences de complĂ©mentation du phĂ©notype de la souche mutante sont indispensables pour confirmer ces rĂ©sultats. Des analyses plus poussĂ©es seront nĂ©cessaires pour comprendre le mĂ©canisme dâadaptation de ce mutant Ă ce milieu
Srn024, un petit ARN impliquĂ© dans lâadaptation du pathogĂšne Streptococcus agalactiae Ă son environnement
International audienceIntroduction et objectifs : Streptococcus agalactiae est la premiĂšre cause dâinfections nĂ©onatales humaines et un pathogĂšne opportuniste pour plusieurs hĂŽtes. Afin de survivre et coloniser lâhĂŽte, la bactĂ©rie sâadapte Ă son environnement en modulant lâexpression de ses gĂšnes. Les petits ARN (sRNA), impliquĂ©s dans cette rĂ©gulation, peuvent eux-mĂȘmes ĂȘtre rĂ©gulĂ©s par les systĂšmes Ă deux composants (TCS). Chez S. agalactiae, quatre sRNA ont Ă©tĂ© identifiĂ©s par RNAseq : Srn015, Srn024, Srn070 et Srn085 [1]. Des prĂ©dictions bio-informatiques indiquent que ces sRNA, nommĂ©s csRNA, seraient rĂ©gulĂ©s par le TCS CiaRH [2]. Les objectifs de ce travail sont de prouver le rĂŽle de CiaRH dans lâexpression de ces sRNA et dâidentifier une cible de Srn024, afin de mieux comprendre les rĂ©seaux de rĂ©gulation bactĂ©riens.MatĂ©riels et mĂ©thodes : Pour prouver lâappartenance de ces sRNA au rĂ©gulon CiaR, leur expression a dâabord Ă©tĂ© quantifiĂ©e par fusions transcriptionnelles dans les souches NEM316WT, NEM316ÎciaRH et NEM316ÎciaRH::ciaRHin situ. La sĂ©quence promotrice TTTAAG-5N-TTTAAG de Srn024, qui semble indispensable Ă la rĂ©gulation des sRNA par la protĂ©ine CiaR, a Ă©tĂ© mutĂ©e afin dâĂ©valuer par fusion transcriptionnelle lâimpact de ces mutations sur lâexpression de Srn024.Des prĂ©dictions bio-informatiques ont Ă©tĂ© rĂ©alisĂ©es pour identifier les cibles potentielles de Srn024. La rĂ©gulation traductionnelle des gĂšnes cibles par Srn024 a Ă©tĂ© Ă©valuĂ©e dans NEM316WT, NEM316Îsrn024 et NEM316Îsrn024::srn024 in situ Ă lâaide dâun plasmide de fusion traductionnelle construit au laboratoire.RĂ©sultats, discussion et conclusion : Les fusions transcriptionnelles ont permis de mettre en Ă©vidence une rĂ©gulation positive des quatre sRNA par le TCS CiaRH. De plus, les mutations rĂ©alisĂ©es dans la sĂ©quence promotrice TTTAAG-5N-TTTAAG montrent que cette sĂ©quence est indispensable pour la rĂ©gulation de Srn024 par CiaR. Les analyses bio-informatiques ont permis dâidentifier lâARNm Gbs1288 comme cible potentielle de Srn024 (-17,17 âg). La fusion traductionnelle a montrĂ© une rĂ©gulation nĂ©gative de cette cible par Srn024. Gbs1288 est une pullulanase produite en prĂ©sence de pullulane et de glycogĂšne dans la souche COH1. Cependant, cette protĂ©ine nâest pas exprimĂ©e en prĂ©sence de glucose [3]. Ces rĂ©sultats semblent indiquer que S. agalactiae sâadapte aux sources nutritives disponibles dans son environnement par le biais de Srn024
Is COVID-19 incriminated in new onset type 2 diabetes mellitus in Lebanese adults?
Abstract Background The effects of COVID-19 on the organism are still being investigated, especially after the transformation of this virus from a respiratory disease in its first appearance to a multi-organ disease that can affect nearly all systems and organs including the endocrinological system. The objective of the study was to find an association between COVID-19 infection and new onset type 2 diabetes in Lebanese adults. Methods A retrospective caseâcontrol study (2019â2022) included 200 subjects, 100 cases with new onset diabetes and 100 controls recruited from endocrinology clinics in rural and suburban located regions of Lebanon. Univariate and multivariate logistic regression were performed. Results Older age (aORâ=â1.07; 95% CI 1.03â1.12), higher BMI (aORâ=â1.32; 95% CI 1.17â1.48), having been infected with COVID-19 (aORâ=â2.38; 95% CI 1.001â5.68) and having a family history of diabetes (aORâ=â11.80; 95% CI 4.23â32.87) were significantly associated with higher odds of having new onset type 2 diabetes after adjusting for multiple risk factors. Conclusion In addition to the traditional risk factors for developing type 2 diabetes, a recent COVID-19 infection was associated with the new onset DM in our study. Subsequently screening for diabetes should be strongly recommended for patients post COVID-19 infection