A Scoping Review of the Oral Microbiome in Preterm Infants.

The purpose of this scoping review was to examine the oral microbiome composition in preterm infants, sampling and collection methods, as well as exposures associated with oral microbiome composition and health implications. We conducted a scoping review of the literature using the Arskey and O'Malley framework. We identified a total of 13 articles which met our inclusion criteria and purpose of this scoping review. Articles included in this review compared the oral microbiome in preterm infants to term infants, examined alterations to the oral microbiome over time, compared the oral microbiome to different body site microbiomes, and explored associations with clinically relevant covariates and outcomes. Exposures associated with the diversity and composition of the oral microbiome in preterm infants included delivery mode, oral feeding, oropharyngeal care, skin-to-skin care, and antibiotics. Day of life and birth weight were also associated with oral microbiome composition. The oral microbiome may be associated with the composition of the tracheal and gut microbiomes, likely due to their proximity. Alpha and beta diversity findings varied across studies as well as the relative abundance of taxa. This is likely due to the different sampling techniques and timing of collection, as well as the wide range of infant clinical characteristics. Multiple factors may influence the composition of the oral microbiome in preterm infants. However, given the heterogeneity of sampling techniques and results within this review, the evidence is not conclusive on the development as well as short- and long-term implications of the oral microbiome in preterm infants and needs to be explored in future research studies. KEY POINTS: · Day of life is a critical factor in oral microbiome development in preterm infants.. · The oral microbiome may be associated with tracheal and gut microbiome colonization.. · Future research should examine sampling methodology for examining the oral microbiome.. · Future research should explore associations with the oral microbiome and adverse health outcomes..

Sociodemographic Factors and Intestinal Microbiome Development in Preterm, Very Low Birth Weight Infants.

OBJECTIVE: Preterm very low birth weight (VLBW) infants are at risk for intestinal morbidities and dysbiotic development of the intestinal microbiome. Despite the influence of sociodemographic factors on premature infant health outcomes, whether they shape the intestinal microbiome early in life is not clear. The objective was to explore the associations between race, sex, and socioeconomic status and the intestinal microbiome of VLBW infants during the first 4 weeks of life. STUDY DESIGN: This was a secondary analysis of data from an ongoing randomized trial of 79 infants ≤30 weeks' gestation and ≤1,500 g. Stool samples were collected at week 1 through week 4, frozen to -80°C and analyzed by 16S rRNA sequencing of the V4 region using Illumina MiSeq. Reads were analyzed to measure α and ß diversity as well as relative abundance of bacteria in the intestinal microbiome. RESULTS: Of the 79 infants, 63 had at least one sample available. Twenty-three (37%) of infants were African American, 30 (48%) were male, and 44 (71%) had Medicaid insurance. There were no statistically significant (<0.05) differences in α diversity or ß diversity, and the differential abundance analysis suggests limited patterns of distinction in the intestinal microbiome between non-African American and African American infants, male and female infants, and infants with maternal private or Medicaid insurance. CONCLUSION: Our results suggest race, sex, and socioeconomic status shape colonization of specific microorganisms to a limited extent. Future studies should confirm these findings and determine clinical relevance through further study of differentially abundant microorganisms and additional factors contributing to colonization patterns. KEY POINTS: · Diversity of the gut microbiome was similar between infants of varying race, sex, and socioeconomic status.. · We observed sociodemographic-linked differences in colonization of individual taxa.. · Further study is required to confirm these results and the clinical relevance of these findings..

Pasteurization of human milk affects the miRNA cargo of EVs decreasing its immunomodulatory activity.

In this report, we evaluated the effect of the pasteurization (P) process of mother's own milk (MOM) on the miRNA content of extracellular vesicles (EVs) and its impact on innate immune responses. Differences in size or particle number were not observed upon pasteurization of MOM (PMOM). However, significant differences were observed in the EV membrane marker CD63 and miRNA profiles. miRNA sequencing identified 33 differentially enriched miRNAs between MOMEV and PMOMEV. These changes correlated with significant decreases in the ability of PMOMEV to modulate IL-8 secretion in intestinal Caco2 cells where only MOMEV were able to decrease IL-8 secretion in presence of TNFα. While EVs from MOMEV and PMOMEV were both able to induce a tolerogenic M2-like phenotype in THP-1 macrophages, a significant decrease in the transcript levels of IL-10 and RNA sensing genes was observed with PMOMEV. Together, our data indicates that pasteurization of MOM impacts the integrity and functionality of MOMEV, decreasing its EVs-mediated immunomodulatory activity. This data provides biomarkers that may be utilized during the optimization of milk processing to preserve its bioactivity.

Vasovagal Syncope at Work: A Narrative Review for an Occupational Management Proposal.

Syncope is a complex clinical manifestation that presents considerable diagnostic difficulties and, consequently, numerous critical issues regarding fitness for work, especially for high-risk tasks. To date, it is impossible to quantify the exact impact of syncope on work and public safety since it is highly improbable to identify loss of consciousness as the fundamental cause of work or driving-related accidents, especially fatal injuries. Working at high-risk jobs such as public transport operators, in high elevations, or with exposure to moving parts, construction equipment, fireworks, or explosives demand attention and total awareness. Currently, no validated criteria or indicators are available for occupational risk stratification of a patient with reflex syncope to return to work. By drawing inspiration from the updated literature, this narrative review intends to summarise the leading knowledge required regarding the return to work for subjects affected by syncope. According to the available data, the authors highlighted some key findings, summarised in macro-items, such as defined risk stratification for vasovagal accidents, return to work after a critical event, and a focus on pacemaker (PM) implementation. Lastly, the authors proposed a flowchart for occupational physicians to help them manage the cases of workers affected by syncope and exposed to levels of risk that could represent a danger to the workers' health.

Antimicrobial Prescribing Practices in Hospital Settings in Italy: A Retrospective Study.

BACKGROUND: This study aims to evaluate the antimicrobial prescribing practices in hospital settings in Italy, focusing on the appropriateness of antibiotic use. METHODS: This study was carried out through a retrospective review of medical records of patients admitted in three public hospitals located in Campania Region (Italy) between 1 January and 31 December 2018. RESULTS: More than one third (34.2%) of patients received at least one inappropriate antibiotic prescription (antibiotic administered and not indicated). Being female, having a >1 Charlson comorbidity index score, and having a longer hospital stay were significant determinants of an inappropriate antibiotic prescription. Instead, patients who had had a non-urgent hospital admission, an infection on hospital admission, and a microbiological culture test during hospital stay were significantly less likely to have an inappropriate prescription. When the antibiotic prescriptions were analyzed, in 26.6% of cases they were not indicated, while among the 687 antibiotic prescriptions with indication, incorrect choice of antibiotics (36.8%) was the most common reason of the inappropriateness. CONCLUSIONS: The findings of the study indicate that the inappropriate use of antibiotics continues to be a relevant issue in the hospital setting and specific interventions are needed to encourage a wider utilization of diagnostic tools to practice targeted therapies and to counter the antimicrobial resistance.

Smoking Habits and Workplace Health Promotion among University Students in Southern Italy: A Cross-Sectional Pilot Investigation.

The study aimed to investigate the tobacco smoking prevalence, habits and awareness among a cohort of healthcare students from a university hospital in southern Italy and the associations with socio-demographic determinants. A secondary outcome was to estimate the educational needs to receive information on smoking-related risk factors. Five hundred and forty-nine students completed a self-administered questionnaire (180 male and 369 female, average age 25 yo, ±5.9 SD), enrolled from October 2018 to November 2019 at the University of Naples 'Luigi Vanvitelli', and the collected data were analysed by descriptive and inferential statistical analysis. The sample's prevalence of current smokers was 25.3%, without a significant sex difference. The multiple logistic regression model showed the link between smoking habits and alcoholic beverage consumption (p < 0.001) and living with smokers (p = 0.003). The enrolled cohort does not seem to need more information about the risks of cigarette smoking (p = 0.028). The data analysis and the comparison with the current literature allowed the authors to hypothesise a training model to be adopted within a workplace health promotion programme managed by an occupational physician. This model included targeted training for smoking dissuasion, focusing on sex and gender, cohabitant's influence, and combined addiction management. Further research will focus on the effectiveness of these proposed models.

Genomic and proteomic characterization of two strains of Shigella flexneri 2 isolated from infants' stool samples in Argentina.

BACKGROUND: Shigella specie is a globally important intestinal pathogen disseminated all over the world. In this study we analyzed the genome and the proteomic component of two Shigella flexneri 2a clinical isolates, collected from pediatric patients with gastroenteritis of the Northwest region of Argentina (NWA) in two periods of time, with four years of difference. Our goal was to determine putative changes at molecular levels occurred during these four years, that could explain the presence of this Shigella`s serovar as the prevalent pathogen in the population under study. RESULTS: As previously reported, our findings support the idea of Shigella has a conserved "core" genome, since comparative studies of CI133 and CI172 genomes performed against 80 genomes obtained from the NCBI database, showed that there is a large number of genes shared among all of them. However, we observed that CI133 and CI172 harbors a small number of strain-specific genes, several of them present in mobile genetic elements, supporting the hypothesis that these isolates were established in the population by horizontal acquisition of genes. These differences were also observed at proteomic level, where it was possible to detect the presence of certain secreted proteins in a culture medium that simulates the host environment. CONCLUSION: Great similarities were observed between the CI133 and CI172 strains, confirming the high percentage of genes constituting the "core" genome of S. flexneri 2. However, numerous strain specific genes were also determined. The presence of the here identified molecular elements into other strain of our culture collation, is currently used to develop characteristic markers of local pathogens. In addition, the most outstanding result of this study was the first description of a S. flexneri 2 producing Colicin E, as one of the characteristics that allows S. flexneri 2 to persist in the microbial community. These findings could also contribute to clarify the mechanism and the evolution strategy used by this pathogen to specifically colonize, survive, and cause infection within the NWA population.

Neonatal Feeding Tube Colonization and the Potential Effect on Infant Health: A Review.

Background: Infants in the neonatal intensive care unit (NICU) often require feeding tubes (FT) for weeks to months. Because FTs are in near constant contact with human milk and/or formula, rapid and extensive bacterial growth is possible. Due to their immature immunologic and gastrointestinal (GI) systems, infants may be at significant health risk due to FT colonization. In adults, length of time FTs remain in place (dwell time) affects the degree of colonization and biofilm formation which is important in infants whose tubes remain in place up to 30 days. Objective: The purpose of this review was to describe and summarize the evidence regarding FT bacterial colonization in infants and identify gaps needing further investigation. Methods: Medline, CINAHL, and Embase databases were searched for clinical and/or laboratory-based observational and randomized controlled studies investigating the presence of bacteria in neonatal FTs. Results: This review of 10 studies found evidence that neonatal FTs may contain high quantities of potentially pathogenic and antibiotic resistant bacteria and longer dwell times may increase the bacterial load. Furthermore, evidence suggests FT colonization may be nosocomial in origin and contribute to adverse infant health. Feeding tubes are an unrecognized source of bacterial colonization which may increase morbidity in premature infants and thus the presence of bacteria in FTs is an important area of investigation in the nutritional care of vulnerable infants in the NICU. Implications: Further appropriately powered studies which are clinically based, use appropriate analyses, and control for potential covariates are necessary to make clinical recommendations.

SARS-CoV-2 emergency in the workplace: are companies ready to protect their workers? A cross-sectional survey.

Purpose. The SARS-CoV-2 pandemic has affected all aspects of everyday life worldwide, including the entire working sector. This study aims to evaluate the response capacity of some Italian companies to the emergency about workers' health and safety. Methods. Data were cross-sectional, collected by a specially drafted 19-item checklist sent to 60 enterprises located in the province of L'Aquila, Abruzzo, Italy. Results. Forty-one companies (68%) responded by filling in the checklist; more than 50% have fewer than 50 employees each and most of the companies belong to the food industry and the financial services. Adherence to the containment measures for the COVID-19 emergency was analysed, especially relating to job organization, social distancing, sanitization and specific training. Large enterprises and the banking sector showed ductile work reorganization according to the containment measures compared to small companies and the food sector. Conclusions. Italian companies have shown a good response to the regulatory restrictions resulting from the SARS-CoV-2 emergency. This is a worthy premise for the imminent management of Phase 2, with the progressive reopening of Italian companies.

Lactobacillus johnsonii N6.2 and Blueberry Phytophenols Affect Lipidome and Gut Microbiota Composition of Rats Under High-Fat Diet.

Obesity is considered a primary contributing factor in the development of many diseases, including cancer, diabetes, and cardiovascular illnesses. Phytochemical-rich foods, associated to healthy gastrointestinal microbiota, have been shown to reduce obesity and associated comorbidities. In the present article, we describe the effects of the probiotic Lactobacillus johnsonii N6.2 and blueberry extracts (BB) on the gut microbiota and lipid profile of rats under a high-fat (HF) or low-calorie (LC) diet. L. johnsonii was found to increase the levels of long chain fatty acids (LCFA) in the serum of all animals under HF diet, while reduced LCFA concentrations were observed in the adipose tissue of animals under HF diet supplemented with BB extracts. All animals under HF diet also showed lower protein levels of SREBP1 and SCAP when treated with L. johnsonii. The gut microbiota diversity, ß-diversity was significantly changed by L. johnsonii in the presence of BB. A significant reduction in α-diversity was observed in the ileum of animals under HF diet supplemented with L. johnsonii and BB, while increased α-diversity was observed in the ilium of animals under LC diet supplemented with L. johnsonii or BB. In summary, L. johnsonii and BB supplementation induced significant changes in gut microbiota diversity and lipid metabolism. The phospholipids pool was the lipidome component directly affected by the interventions. The ileum and colon microbiota showed clear differences depending on the diet and the treatments examined.

Frozen Mother's Own Milk Can Be Used Effectively to Personalize Donor Human Milk.

Feeding preterm infants mother's own milk (MOM) lowers rates of sepsis, decreases necrotizing enterocolitis, and shortens hospital stay. In the absence of freshly expressed MOM, frozen MOM (FMOM) is provided. When MOM is unavailable, preterm infants are often fed pasteurized donor human milk (DHM), rendering it devoid of beneficial bacteria. We have previously reported that when MOM is inoculated into DHM to restore the live microbiota [restored milk (RM)], a similar microbial diversity to MOM can be achieved. Yet, it is unknown if a similar diversity to MOM can be obtained when FMOM is inoculated into DHM. The goal of this study was to determine whether a similar microbial composition to MOM could be obtained when FMOM is used to personalize DHM. To this end, a fresh sample of MOM was obtained and divided into fresh and frozen fractions. MOM and FMOM were inoculated into DHM at different dilutions: MOM/FMOM 10% (RM/FRM10) and MOM/FMOM 30% (RM/FRM30) and incubated at 37°C. At different timepoints, culture-dependent and culture-independent techniques were performed. Similar microbiota expansion and alpha diversity were observed in MOM, RM10, and RM30 whether fresh or frozen milk was used as the inoculum. To evaluate if microbial expansion would result in an abnormal activation on the innate immune system, Caco-2 epithelial cells were exposed to RM/FRM to compare interleukin 8 levels with Caco-2 cells exposed to MOM or DHM. It was found that RM samples did not elicit a significant increase in IL-8 levels when compared to MOM or FMOM. These results suggest that FMOM can be used to inoculate DHM if fresh MOM is unavailable or limited in supply, allowing both fresh MOM and FMOM to be viable options in a microbial restoration strategy.

Metabolomic Profile of Personalized Donor Human Milk.

Human milk could be considered an active and complex mixture of beneficial bacteria and bioactive compounds. Since pasteurization drastically reduces the microbial content, we recently demonstrated that pasteurized donor human milk (DHM) could be inoculated with different percentages (10% and 30%) of mother's own milk (MOM) to restore the unique live microbiota, resulting in personalized milk (RM10 and RM30, respectively). Pasteurization affects not only the survival of the microbiota but also the concentration of proteins and metabolites, in this study, we performed a comparative metabolomic analysis of the RM10, RM30, MOM and DHM samples to evaluate the impact of microbial restoration on metabolite profiles, where metabolite profiles clustered into four well-defined groups. Comparative analyses of DHM and MOM metabolomes determined that over one thousand features were significantly different. In addition, significant changes in the metabolite concentrations were observed in MOM and RM30 samples after four hours of incubation, while the concentration of metabolites in DHM remained constant, indicating that these changes are related to the microbial expansion. In summary, our analyses indicate that the metabolite profiles of DHM are significantly different from that of MOM, and the profile of MOM may be partially restored in DHM through microbial expansion.

Epidemiological study of prevalent pathogens in the Northwest region of Argentina (NWA).

Northwest Argentina (NWA) is a poor economic-geographical region, with the highest rate of diarrhea diseases. At the moment, there are no reports showing the epidemiological status of this region that would allow to establish methods for prevention and control of these infections and to indicate of the prevalent pathogen that produces them. Therefore we carried out an epidemiological study of the gastroenteritis etiological agents and their incidence in the pediatric population. A total of 17 823 fecal samples were collected, 14 242 from HNJ-Tuc, 2,257 from CePSI-Stgo and 1,324 from HINEP-Cat. In 2,595 samples a bacterial agent was identified, the 93.64% corresponded to Shigella/Salmonella clinical isolates. Shigella genus was the prevalent pathogen, being Shigella flexneri 2 the most frequent serotype. Most of the Shigella clinical isolates presented themselves as multidrug-resistant (MDR), harboring 2 to 3 genetic resistance determinants. 50% of the affected patients were children under 4 years old. Here, we demonstrate that bacterial gastrointestinal diseases strongly affect the health of NWA population. The appearance of epidemic outbreaks, as happened during 2014, suggest that they may be related to the socio-economic poverty of NWA. Recently, Shigella flexneri 2 has become the highest NWA´s incidence infectious agent. The acquisition of new antibiotic resistance determinants may play an important role in their adaptation and persistence.

Tuberculosis Infection Screening in 5468 Italian Healthcare Students: Investigation of a Borderline Zone Value for the QFT-Test.

Healthcare workers are at an increased risk of contracting Mycobacterium tuberculosis infection. Tuberculin skin test (TST) and interferon gamma release assay (IGRA) represent the available tests most used for the diagnosis of latent tuberculosis infection (LTBI). Different borderline zones have been proposed for defining conversions and reversions to improve the interpretation of the IGRA test results as part of serial testing. From 2012 to 2017, 5468 health students of an Italian University Hospital were screened for tuberculosis infection through the execution of the TST and, in case of positivity, of the QuantiFERON-TB® Gold In-Tube assay (QFT-GIT). The QFT-GIT is considered "borderline" with values from 0.35 to 0.99 IU/mL. Among the students who performed the QFT-GIT assay, 27 subjects presented a range of values defined as borderline. The QFT-GIT was repeated after 90 days on 19 subjects with borderline values and showed a negativization of the values in 14 students and a positive conversion in three cases, while for two students, a borderline value was also found for the second test, with a 74% regression of the borderline cases. The introduction of QuantiFERON borderline values is a useful assessment tool to bring out LTBI case candidates for chemoprophylaxis.

Healthcare Workers and Manual Patient Handling: A Pilot Study for Interdisciplinary Training.

Manual patient handling (MPH) is a major occupational risk in healthcare settings. The aim of this study was to propose an MPH training model involving interdisciplinary aspects. A scheduled training program was performed with 60 healthcare workers (HCWs) from a hospital in Naples, Italy, providing training divided into three sections (occupational health-section one; physical therapy-section two; psychosocial section-section three) and lasting six hours. Fifty-two HCWs performed the training session. In section one, a questionnaire about risk perception related to specific working tasks was administered. Section two provided specific exercises for the postural discharge of the anatomical areas most involved in MPH. The last section provided teamwork consolidation through a role-playing exercise. The training program could also be useful for risk assessment itself, as they can examine the perceptions of the specific risk of the various workers and incorrect attitudes and therefore correct any incorrect procedures, reducing exposure to specific risks in the field. This pilot study proposes a training model that explores all aspects related to MPH risk exposure and also underlines the need for standardization of this formative model, which could represent a useful tool for studying the real effectiveness of training in workplaces.

HBV vaccination status among healthcare workers: A cross-sectional study.

OBJECTIVE: The development of a vaccine against hepatitis B virus (HBV) is one of the improvements in strategy prevention during the last decades. AIM: To evaluate HBV-related vaccine status in healthcare workers (HCW) exposed to biological risk. METHODS: The serum markers for HBV were collected from HCWs in two tertiary care hospitals in Naples (Italy). Multivariate statistical analysis was then performed to identify associated factors linked to the long-term immunogenicity of the HCWs. RESULTS: All HBV vaccinated individuals were screened for whole marker patterns; all were HBsAg/anti-HBc negative. Of individuals, 20% had an anti-HB antibody titre < 10 IU/L. Multivariate statistical analysis highlighted that women were more protected than men (73.6% vs. 26.4%, P < 0.05). Additionally, nurses seem to maintain a higher antibody titre than doctors and other staff, such as auxiliary technicians (P < 0.05). CONCLUSIONS: Our data support the evidence of a strong immunogenicity against HBV, assessed through the circulating antibody titre, when prophylactic vaccination is conducted in non-infantile age, particularly for women. The outcome of the study supports the central role of occupational physicians within the hospital districts in terms of primary prevention and maximum protection of HCWs.

RcsB-dependent effects on nar operon regulation during the aerobic growth of Salmonella Typhimurium.

The intracellular pathogen Salmonella is an important cause of human foodborne diseases worldwide. Salmonella takes advantage of the phosphorelay regulatory systems to survive in the hostile environment of the host's gastrointestinal tract. It has been reported that the nitrate reductase Z (NR-Z), encoded by the narUZYV operon, is required during Salmonella transition to anaerobic environments and is constitutively produced at low levels, but little is known about the regulatory mechanism involved in the operon gene expression. In this work, we found that the RcsCDB system is activated by high concentrations of specific sugars as a carbon source. In this activation state, the RcsCDB system participates in the negative control of narUZYWV expression. This control strategy occurs during exponential growth when the carbon source is high, allowing for normal aerobic respiration. The RcsCDB system's participation in aerobic respiration is necessary to ensure efficient metabolism and optimal energy consumption when the bacteria are growing exponentially.

Cross-talk between the RcsCDB and RstAB systems to control STM1485 gene expression in Salmonella Typhimurium during acid-resistance response.

Bacterial survive and respond to adverse changes in the environment by regulating gene transcription through two-component regulatory systems. In Salmonella Typhimurium the STM1485 gene expression is induced under low pH (4.5) during replication inside the epithelial host cell, but it is not involved in sensing or resisting to this condition. Since the RcsCDB system is activated under acidic conditions, we investigated whether this system is able to modulate STM1485 expression. We demonstrated that acid-induced activation of the RcsB represses STM1485 transcription by directly binding to the promoter. Under the same condition, the RstA regulator activates the expression of this gene. Physiologically, we observed that RcsB-dependent repression is required for the survival of bacteria when they are exposed to pancreatic fluids. We hypothesized that STM1485 plays an important role in Salmonella adaptation to pH changes, during transition in the gastrointestinal tract. We suggest that bacteria surviving the gastrointestinal environment invade the epithelial cells, where they can remain in vacuoles. In this new environment, acidity and magnesium starvation activate the expression of the RstA regulator in a PhoPQ-dependent manner, which in turn induces STM1485 expression. These levels of STM1485 allow increased bacterial replication within vacuoles to continue the course of infection.

Regulatory Effect of SlyA on rcsB Expression in Salmonella enterica Serovar Typhimurium.

The Salmonella enterica serovar Typhimurium RcsCDB system regulates the synthesis of colanic acid and the flagellum as well as the expression of virulence genes. We previously demonstrated that the rcsC11 mutant, which constitutively activates the RcsB regulator, attenuates Salmonella virulence in an animal model. This attenuated phenotype was also produced by deletion of the slyA gene. In this work, we investigated if this antagonistic behavior is produced by modulating the expression of both regulator-encoding genes. We demonstrated that SlyA overproduction negatively regulates rcsB transcription. A bioinformatics analysis enabled us to identify putative SlyA binding sites on both promoters, P rcsDB and P rcsB , which control rcsB transcriptional levels. We also determined that SlyA is able to recognize and bind to these predicted sites to modulate the activity of both rcsB promoters. According to these results, SlyA represses rcsB transcription by direct binding to specific sites located on the rcsB promoters, thus accounting for the attenuated/virulence antagonistic behaviors. Moreover, we showed that the opposite effect between both regulators also physiologically affects the Salmonella motility phenotype. In this sense, we observed that under SlyA overproduction, P rcsB is repressed, and consequently, bacterial motility is increased. On the basis of these results, we suggest that during infection, the different RcsB levels produced act as a switch between the virulent and attenuated forms of Salmonella Thereby, we propose that higher concentrations of RcsB tilt the balance toward the attenuated form, while absence or low concentrations resulting from SlyA overproduction tilt the balance toward the virulent form.IMPORTANCE The antagonistic behavior of RcsB and SlyA on virulence gene expression led us to hypothesize that there is interplay between both regulators in a regulatory network and these could be considered coordinators of this process. Here, we report that the SlyA virulence factor influences motility behavior by controlling rcsB transcription from the P rcsB promoter. We also demonstrate that SlyA negatively affects the expression of the rcsB gene by direct binding to P rcsDB and P rcsB promoters. We suggest that different levels of RcsB act as a switch between the virulent and attenuated forms of Salmonella, where high concentrations of the regulator tend to tilt the balance toward the attenuated form and low concentrations or its absence tilt it toward the virulent form.

Low-Level Radiofrequency Exposure Does Not Induce Changes in MSC Biology: An in vitro Study for the Prevention of NIR-Related Damage.

BACKGROUND: The ubiquitous diffusion of radiofrequency (RF) radiation across human living environments has attracted the attention of scientists. Though the adverse health effects of RF exposure remain debatable, it has been reported that the interaction of such radiation with biological macromolecular structures can be deleterious for stem cells, inducing impairment of their main functions involving self-renewal and differentiation. PURPOSE: The purpose of this study was to determine whether exposure to RF of 169 megahertz (MHz) that is part of very high radiofrequency (VHF) range 30-300 MHz, could cause damage to stem cells by inducing senescence and loss of regenerative and DNA repair capacity. METHODS: The study was conducted on mesenchymal stromal cells (MSCs) containing a subpopulation of stem cells. The MSCs were exposed to RFs of 169 MHz administered via an open meter 2G "Smart Meter" for different durations of time. RESULT: We did not observe modifications in MSC biology as a result of the RF exposure conducted in our experiments. CONCLUSION: We concluded that MSCs are insensitive to RF radiation exposure at 169 MHz for various time intervals, including longer durations.