Val43 residue of NsrR is crucial for the nitric oxide response of Salmonella Typhimurium.

ABSTRACT: In pathogenic bacteria, the flavohemoglobin Hmp is crucial in metabolizing the cytotoxic levels of nitric oxide (NO) produced in phagocytic cells, contributing to bacterial virulence. Hmp expression is predominantly regulated by the Rrf2 family transcription repressor NsrR in an NO-dependent manner; however, the underlying molecular mechanism in enterobacteria remains poorly understood. In this study, we identified Val43 of Salmonella Typhimurium NsrR (StNsrR) as a critical amino acid residue for regulating Hmp expression. The Val43-to-Ala-substituted mutant NsrR isolated through random and site-directed mutagenesis showed high binding affinity to the target DNA irrespective of NO exposure, resulting in a severe reduction in hmp transcription and slow NO metabolism in Salmonella under NO-producing conditions. Conversely, the Val43-to-Glu-substituted NsrR caused effects similar to nsrR null mutation, which directed hmp transcription and NO metabolism in a constitutive way. Comparative analysis of the primary sequences of NsrR and another NO-sensing Rrf2 family regulator, IscR, from diverse bacteria, revealed that Val43 of enterobacterial NsrR corresponds to Ala in Pseudomonas aeruginosa or Streptomyces coelicolor NsrR and Glu in enterobacterial IscR, all of which are located in the DNA recognition helix α3. The predicted structure of StNsrR in complex with the hmp DNA suggests dissimilar spatial stoichiometry in the interactions of Val43 and its substituted residues with the target DNA, consistent with the observed phenotypic changes in StNsrR Val43 mutants. Our findings highlight the discriminative roles of the NsrR recognition helix in regulating species-specific target gene expression, facilitating effective NO detoxification strategies in bacteria across diverse environments. IMPORTANCE: The precise regulation of flavohemoglobin Hmp expression by NsrR is critical for bacterial fitness, as excessive Hmp expression in the absence of NO can disturb bacterial redox homeostasis. While the molecular structure of Streptomyces coelicolor NsrR has been recently identified, the specific molecular structures of NsrR proteins in enterobacteria remain unknown. Our discovery of the crucial role of Val43 in the DNA recognition helix α3 of Salmonella NsrR offers valuable insights into the Hmp modulation under NO stress. Furthermore, the observed amino acid polymorphisms in the α3 helices of NsrR proteins across different bacterial species suggest the diverse evolution of NsrR structure and gene regulation in response to varying levels of NO pressure within their ecological niches.

[Clostridioides Infection in Patients with Inflammatory Bowel Disease].

Inflammatory bowel disease (IBD), comprising Crohn's disease and ulcerative colitis, is a chronic inflammatory condition of the gastrointestinal tract, which is often accompanied by altered gut microbial composition. Gut dysbiosis in IBD is considered to be the reason for the high risk of Clostridioides difficile infection (CDI) in patients with IBD. Therefore, CDI should be evaluated in IBD patients with a symptom flare. Medical treatment of non-severe CDI in IBD is similar to that in non-IBD patients and includes oral vancomycin or fidaxomicin. The risk of recurrent CDI in IBD is higher than in non-IBD patients and this could be mitigated by fecal microbiota transplantation. As CDI may worsen the clinical outcomes of IBD, patients should be carefully monitored and an escalation of IBD therapy needs to be considered when there is no improvement seen with the antimicrobial treatment of CDI. This review discusses the risk, pathophysiology, diagnosis, and management of CDI in IBD.

Loss of FrmB results in increased size of developmental structures during the multicellular development of Dictyostelium cells.

FERM domain-containing proteins are involved in diverse biological and pathological processes, including cell-substrate adhesion, cell-cell adhesion, multicellular development, and cancer metastasis. In this study, we determined the functions of FrmB, a FERM domain-containing protein, in the cell morphology, cell adhesion, and multicellular development of Dictyostelium cells. Our results show that FrmB appears to play an important role in regulating the size of developmental structures. frmB null cells showed prolonged aggregation during development, resulting in increased size of developmental structures, such as mounds and fruiting bodies, compared to those of wild-type cells, whereas FrmB overexpressing cells exhibited decreased size of developmental structures. These results suggest that FrmB may be necessary for limiting the sizes of developmental structures. Loss of FrmB also resulted in decreased cell-substrate adhesion and slightly increased cell area, suggesting that FrmB had important roles in the regulation of cell adhesion and cell morphology. These studies would contribute to our understanding of the intertwined and overlapped functions of FERM domain-containing proteins.

Clinical Significance of Postinfarct Fever in ST-Segment Elevation Myocardial Infarction: A Cardiac Magnetic Resonance Imaging Study.

BACKGROUND: Little is known about causality and pathological mechanism underlying association of postinfarct fever with myocardial injury in patients with ST-segment elevation myocardial infarction. METHODS AND RESULTS: In 276 patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction, cardiac magnetic resonance imaging was performed a median of 3.4 days after the index procedure. Forty-five patients had postinfarct fever (peak body temperature within 4 days after primary percutaneous coronary intervention ≥37.7°C; Fever group) whereas 231 did not (no-Fever group). Primary outcome was myocardial infarct size as assessed by cardiac magnetic resonance imaging. Secondary outcomes were extent of area at risk, myocardial salvage index, and microvascular obstruction area. In cardiac magnetic resonance imaging analysis, myocardial infarct size (25.6% [19.7-32.4] in the Fever group versus 17.2% [11.8-25.4] in the no-Fever group; P<0.01), extent of area at risk (43.7% [31.9-54.9] versus 35.3% [24.0-43.7]; P<0.01), and microvascular obstruction area (4.4% [0.0-13.2] versus 1.2% [0.0-5.1]; P=0.02) were greater in the Fever group than in the no-Fever group. Myocardial salvage index tended to be lower in the Fever group compared to the no-Fever group (37.7 [28.5-56.1] versus 47.0 [34.1-56.8]; P=0.13). In multivariate analysis, postinfarct fever was associated with larger myocardial infarct (odds ratio, 3.48; 95% CI, 1.71-7.07; P<0.01) and lower MSI (odds ratio, 2.10; 95% CI, 1.01-4.08; P=0.03). CONCLUSIONS: Postinfarct fever could predict advanced myocardial injury and less salvaged myocardium in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention.

Normal Echocardiographic Measurements in a Korean Population Study: Part II. Doppler and Tissue Doppler Imaging.

BACKGROUND: Hemodynamic and functional evaluation with Doppler and tissue Doppler study as a part of comprehensive echocardiography is essential but normal reference values have never been reported from Korean normal population especially according to age and sex. METHODS: Using Normal echOcaRdiographic Measurements in a KoreAn popuLation study subjects, we obtained normal reference values for Doppler and tissue Doppler echocardiography including tricuspid annular velocities according to current guidelines and compared values according to gender and age groups. RESULTS: Mitral early diastolic (E) and late diastolic (A) velocity as well as E/A ratio were significantly higher in women compared to those in men. Conversely, mitral peak systolic and late diastolic annular velocity in both septal and lateral mitral annulus were significantly lower in women compared to those in men. However, there were no significant differences in both septal and lateral mitral early diastolic annular (e') velocity between men and women. In both men and women, mitral E velocity and its deceleration time as well as both E/A and E/e' ratio considerably increased with age. There were no significant differences in tricuspid inflow velocities and tricuspid lateral annular velocities between men and women except e' velocity, which was significantly higher in women compared to that in men. However, changes in both tricuspid inflow and lateral annular velocities according to age were similar to those in mitral velocities. CONCLUSION: Since there were significant differences in Doppler and tissue Doppler echocardiographic variables between men and women and changes according to age were even more considerable in both gender groups, normal Doppler echocardiographic values should be differentially applied based on age and sex.

Normal 2-Dimensional Strain Values of the Left Ventricle: A Substudy of the Normal Echocardiographic Measurements in Korean Population Study.

BACKGROUND: It is important to understand the distribution of 2-dimensional strain values in normal population. We performed a multicenter trial to measure normal echocardiographic values in the Korean population. METHODS: This was a substudy of the Normal echOcardiogRaphic Measurements in KoreAn popuLation (NORMAL) study. Echocardiographic specialists measured frequently used echocardiographic indices in healthy people according to a standardized method at 23 different university hospitals. The strain values were analyzed from digitally stored images. RESULTS: Of a total of 1003 healthy participants in NORMAL study, 2-dimensional strain values were measured in 501 subjects (265 females, mean age 47 ± 15 years old) with echocardiographic images only by GE echocardiographic machines. Interventricular septal thickness, left ventricular (LV) posterior wall thickness, systolic and diastolic LV dimensions, and LV ejection fraction were 7.5 ± 1.0 mm, 7.4 ± 1.0 mm, 29.9 ± 2.8 mm, 48.9 ± 3.6 mm, and 62 ± 4%, respectively. LV longitudinal systolic strain (LS) values of apical 4-chamber (A4C) view, apical 3-chamber (A3C) view, apical 2-chamber (A2C) view, and LV global LS (LVGLS) were -20.1 ± 2.3, -19.9 ± 2.7, -21.2 ± 2.6, and -20.4 ± 2.2%, respectively. LV longitudinal systolic strain rate (LVLSR) values of the A4C view, A3C view, A2C view, and LV global LSR (LVGLSR) were -1.18 ± 0.18, -1.20 ± 0.21, -1.25 ± 0.21, and -1.21 ± 0.21-s, respectively. Females had lower LVGLS (-21.2 ± 2.2% vs. -19.5 ± 1.9%, p < 0.001) and LVGLSR (-1.25 ± 0.18-s vs. -1.17 ± 0.15-s, p < 0.001) values than males. CONCLUSION: We measured LV longitudinal strain and strain rate values in the normal Korean population. Since considerable gender differences were observed, normal echocardiographic cutoff values should be differentially applied based on sex.

Normal Echocardiographic Measurements in a Korean Population Study: Part I. Cardiac Chamber and Great Artery Evaluation.

BACKGROUND: Measurement of the cardiac chamber is essential, and current guidelines recommend measuring and reporting values for both sides of the cardiac chamber during echocardiographic evaluation. Normal echocardiographic reference values have been suggested previously, but detailed information about right-sided chambers and values according to gender was not included. METHODS: This is a prospective multicenter (23 centers) study evaluating normal Korean adult subjects using comprehensive echocardiography. We included normal adult subjects (age; 20-79 years old) who had no significant cardiac disorders or illnesses, such as hypertension or diabetes, which could affect cardiac structure and function. We measured the cardiac chamber including both right and left ventricles as well as atria according to current echocardiography guidelines and compared values according to gender and age groups. RESULTS: A total of 1003 subjects were evaluated and the mean age was 48 ± 16 years. Left ventricular (LV) dimensions increased, but LV volume decreased in older subjects. Right ventricular (RV) area decreased in women and older subjects, and the RV long-axis dimension showed a similar trend. Left atrial (LA) volume increased in men but there were no differences in LA volume index between men and women. The dimension of great arteries increased in men and older subjects. CONCLUSION: Since there were considerable differences between men and women and in the different age groups, and the trends differed significantly between different echo variables, normal echocardiographic cutoff values should be differentially applied based on age and gender.

The role of rpoS, hmp, and ssrAB in Salmonella enterica Gallinarum and evaluation of a triple-deletion mutant as a live vaccine candidate in Lohmann layer chickens.

Salmonella enterica Gallinarum (SG) causes fowl typhoid (FT), a septicemic disease in avian species. We constructed deletion mutants lacking the stress sigma factor RpoS, the nitric oxide (NO)-detoxifying flavohemoglobin Hmp, and the SsrA/SsrB regulator to confirm the functions of these factors in SG. All gene products were fully functional in wild-type (WT) SG whereas mutants harboring single mutations or a combination of rpoS, hmp, and ssrAB mutations showed hypersusceptibility to H2O2, loss of NO metabolism, and absence of Salmonella pathogenicity island (SPI)-2 expression, respectively. A triple-deletion mutant, SGΔ3 (SGΔrpoSΔhmpΔssrAB), was evaluated for attenuated virulence and protection efficacy in two-week-old Lohmann layer chickens. The SGΔ3 mutant did not cause any mortality after inoculation with either 1 × 10(6) or 1 × 10(8) colony-forming units (CFUs) of bacteria. Significantly lower numbers of salmonellae were recovered from the liver and spleen of chickens inoculated with the SGΔ3 mutant compared to chickens inoculated with WT SG. Vaccination with the SGΔ3 mutant conferred complete protection against challenge with virulent SG on the chickens comparable to the group vaccinated with a conventional vaccine strain, SG9R. Overall, these results indicate that SGΔ3 could be a promising candidate for a live Salmonella vaccine against FT.

Clinical features of right-sided infective endocarditis occurring in non-drug users.

Right-sided infective endocarditis (RIE) occurs predominantly in intravenous drug users in western countries, and it has a relatively good prognosis. Clinical features and prognosis of RIE occurring in non-drug users are not well known. We investigated the clinical findings of RIE in non-drug users. We retrospectively reviewed 345 cases diagnosed with IE. Cases with RIE or left-sided infective endocarditis (LIE) defined by the vegetation site were included and cases having no vegetation or both-side vegetation were excluded. Clinical findings and in-hospital outcome of RIE were compared to those of LIE. Among the 245 cases, 39 (16%) cases had RIE and 206 (84%) cases had LIE. RIE patients were younger (40 ± 19 yr vs 50 ± 18 yr, P=0.004), and had a higher incidence of congenital heart disease (CHD) (36% vs 13%, P<0.001) and central venous catheter (CVC) (21% vs 4%, P=0.001) compared to LIE patients. A large vegetation was more common in RIE (33% vs 9%, P<0.001). Staphylococcus aureus was the most common cause of RIE, while Streptococcus viridans were the most common cause of LIE. In-hospital mortality and cardiac surgery were not different between the two groups. CHD and use of CVC were common in non-drug users with RIE. The short-term clinical outcome of RIE is not different from that of LIE.

The I/LWEQ domain in RapGAP3 required for posterior localization in migrating cells.

Cell migration requires a defined cell polarity which is formed by diverse cytoskeletal components differentially localized to the poles of cells to extracellular signals. Rap- GAP3 transiently and rapidly translocates to the cell cortex in response to chemoattractant stimulation and localizes to the leading edge of migrating cells. Here, we examined localization of truncated RapGAP3 proteins and found that the I/LWEQ domain in the central region of RapGAP3 was sufficient for posterior localization in migrating cells, as opposed to leading-edge localization of full-length Rap- GAP3. All truncated proteins accumulated at the leading edge of migrating cells exhibited clear translocation to the cell cortex in response to stimulation, whereas proteins localized to the posterior in migrating cells displayed no translocation to the cortex. The I/LWEQ domain appears to passively accumulate at the posterior region in migrating cells due to exclusion from the extended front region in response to chemoattractant stimulation rather than actively being localized to the back of cells. Our results suggest that posterior localization of the I/LWEQ domain of RapGAP3 is likely related to F-actin, which has probably different properties compared to newly formed F-actin at the leading edge of migrating cells, at the lateral and posterior regions of the cell.

RapGAP9 regulation of the morphogenesis and development in Dictyostelium.

Recent reports have demonstrated that the importance of Rap1-specific GTPase-activating proteins (GAPs) in the spatial and temporal regulation of Rap1 activity during cell migration and development in Dictyostelium. Here, we identified another putative Rap1 GAP-domain containing protein, showing high sequence homologies with those of human Rap1GAP and Dictyotelium RapGAP3, by bioinformatic search. Loss of RapGAP9 resulted in some defects in morphogenesis and development in Dicytostelium. rapGAP9 null cells were more flattened and spread, and highly multinucleated. Compared to wild-type cells, cells lacking RapGAP9 exhibited increased levels of F-actin and more filopodia. These results suggest that RapGAP9 is involved in the regulation of cytoskeleton reorganization and cytokinesis. rapGAP9 null cells showed a small increase of cell-substratum attachment and slightly lower moving speed and directionality compared to wild-type cells. In addition, the loss of RapGAP9 resulted in an altered morphology of fruiting body with a shorter length of stalk and spore. Identification and characterization of RapGAP9 in this study will provide further insights into the molecular mechanism by which Rap1 regulates cytoskeleton reorganization and morphogenesis in Dictyostelium.

Cell migration: regulation of cytoskeleton by Rap1 in Dictyostelium discoideum.

Cell movement involves a coordinated regulation of the cytoskeleton, F-actin-mediated protrusions at the front and myosin-mediated contraction of the posterior of a cell. The small GTPase Rap1 functions as a key regulator in the spatial and temporal control of cytoskeleton reorganization for cell migration. This review outlines the establishment of cell polarity by differential localizations of the cytoskeleton and discusses the spatial and temporal regulation of cytoskeleton reorganization via the Rap1 signaling pathway during chemotaxis with a focus on recent advances in the study of chemotaxis using a simple eukaryotic model organism, Dictyostelium discoideum.

Extraosseous osteosarcoma: single institutional experience in Korea.

AIM: Extraosseous osteosarcoma (EOO) is a rare soft tissue form of osteosarcoma without involvement of the skeletal system. Due to the rarity of disease, its clinical features and optimal treatment are yet to be defined. METHODS: Between 1 January 1999 and 30 June 2008 ten patients were pathologically confirmed with extra-skeletal osteosarcoma. A retrospective analysis of the ten patients was performed. RESULTS: The anatomical distribution of the osteosarcomas was as follows: lower extremities (n = 3), upper extremities (n = 2), breast (n = 2), lung (n = 1), cheek (n = 1) and retroperitoneum (n = 1). Nine patients initially underwent resection of the primary mass. One patient, who received six cycles of adjuvant doxorubicin and cisplatin chemotherapy was alive in remission at 42.6 months. One patient with postoperative radiotherapy after curative surgery was alive in remission at 6.2 months. However, all three patients who received curative resection but no postoperative radiotherapy or chemotherapy died of the disease at 10.7, 11.1 and 15.6 months after surgery. The median time to failure was only 4.4 months (95% CI, 0.6, 8.2 months) and the median survival time of all patients was only 11.1 months (95% CI, 5.6, 16.6 months). At the time of analysis, seven patients were dead and all died of the disease recurrence. CONCLUSION: EOO should be treated as a soft tissue sarcoma with aggressive behavior and multimodality treatment should be actively sought to improve treatment outcome. The impact of adjuvant chemotherapy on survival of EOO needs further investigation.