Catabolite control protein C contributes to virulence and hydrogen peroxide-induced oxidative stress responses in Listeria monocytogenes.

Listeria monocytogenes causes listeriosis, an infectious and potentially fatal disease of animals and humans. A diverse network of transcriptional regulators, including LysR-type catabolite control protein C (CcpC), is critical for the survival of L. monocytogenes and its ability to transition into the host environment. In this study, we explored the physiological and genetic consequences of deleting ccpC and the effects of such deletion on the ability of L. monocytogenes to cause disease. We found that ccpC deletion did not impact hemolytic activity, whereas it resulted in significant reductions in phospholipase activities. Western blotting revealed that the ΔccpC strain produced significantly reduced levels of the cholesterol-dependent cytolysin LLO relative to the wildtype F2365 strain. However, the ΔccpC mutant displayed no significant intracellular growth defect in macrophages. Furthermore, ΔccpC strain exhibited reduction in plaque numbers in fibroblasts compared to F2365, but plaque size was not significantly affected by ccpC deletion. In a murine model system, the ΔccpC strain exhibited a significantly reduced bacterial burden in the liver and spleen compared to the wildtype F2365 strain. Interestingly, the deletion of this gene also enhanced the survival of L. monocytogenes under conditions of H2O2-induced oxidative stress. Transcriptomic analyses performed under H2O2-induced oxidative stress conditions revealed that DNA repair, cellular responses to DNA damage and stress, metalloregulatory proteins, and genes involved in the biosynthesis of peptidoglycan and teichoic acids were significantly induced in the ccpC deletion strain relative to F2365. In contrast, genes encoding internalin, 1-phosphatidylinositol phosphodiesterase, and genes associated with sugar-specific phosphotransferase system components, porphyrin, branched-chain amino acids, and pentose phosphate pathway were significantly downregulated in the ccpC deletion strain relative to F2365. This finding highlights CcpC as a key factor that regulates L. monocytogenes physiology and responses to oxidative stress by controlling the expression of important metabolic pathways.

Development of Bioluminescent Virulent Aeromonas hydrophila for Understanding Pathogenicity.

Virulent Aeromonas hydrophila (vAh) strains that cause motile Aeromonas septicemia (MAS) in farmed channel catfish (Ictalurus punctatus) have been an important problem for more than a decade. However, the routes of infection of vAh in catfish are not well understood. Therefore, it is critical to study the pathogenicity of vAh in catfish. To this goal, a new bioluminescence expression plasmid (pAKgfplux3) with the chloramphenicol acetyltransferase (cat) gene was constructed and mobilized into vAh strain ML09-119, yielding bioluminescent vAh (BvAh). After determining optimal chloramphenicol concentration, plasmid stability, bacteria number-bioluminescence relationship, and growth kinetics, the catfish were challenged with BvAh, and bioluminescent imaging (BLI) was conducted. Results showed that 5 to 10 µg/mL chloramphenicol was suitable for stable bioluminescence expression in vAh, with some growth reduction. In the absence of chloramphenicol, vAh could not maintain pAKgfplux3 stably, with the half-life being 16 h. Intraperitoneal injection, immersion, and modified immersion (adipose fin clipping) challenges of catfish with BvAh and BLI showed that MAS progressed faster in the injection group, followed by the modified immersion and immersion groups. BvAh was detected around the anterior mouth, barbels, fin bases, fin epithelia, injured skin areas, and gills after experimental challenges. BLI revealed that skin breaks and gills are potential attachment and entry portals for vAh. Once vAh breaches the skin or epithelial surfaces, it can cause a systemic infection rapidly, spreading to all internal organs. To our best knowledge, this is the first study that reports the development of a bioluminescent vAh and provides visual evidence for catfish-vAh interactions. Findings are expected to provide a better understanding of vAh pathogenicity in catfish.

Investigating the Role of Oxidative Stress in Benign Paroxysmal Positional Vertigo with Spot Urine.

Objectives: The objectives of this study were to evaluate the role of oxidative stress in benign paroxysmal positional vertigo (BPPV) by measuring urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), 8-hydroxy-guanosine (8-OHG), and 8-hydroxy-guanine levels. Methods: Thirty-one adult female patients diagnosed with BPPV were included in this study. Patients with central pathologies and other peripheral causes of vertigo were excluded from the study. The patients were evaluated for oxidative stress during and after the BPPV attack with blood samples and spot urine tests. Depression, anxiety, and stress scale (DASS) questionnaire was used to evaluate emotional stress. A control group consisting of 30 age-matched healthy women was formed. Results: Urinary oxidative stress values during the attack were significantly higher than the post-treatment group and the healthy control group (p<0.05). There was no significant difference between the urinary oxidative stress values of the BPPV group after treatment and the healthy control group (p>0.05). DASS scores were significantly higher during the attack and after the treatment compared to the healthy control group (p<0.05). Conclusion: The increase in spot urinary 8-OHdG, 8-OHG, and 8-hydroxy-guanine levels can be used as a biomarker for oxidative stress in patients with BPPV. Furthermore, emotional stress can also trigger BPPV attacks by increasing oxidative stress.

Middle Ear Adenomatous Neuroendocrine Tumor: A Case Report and Review of Literature.

Middle ear adenomatous neuroendocrine tumor (MEANT) is a rare entity and accounts for approximately 2% of all middle ear tumors. Histologically, the presence of neuroendocrine and glandular structures has led to the use of a wide variety of terminologies such as adenoma, carcinoid tumor, and neuroendocrine tumor. The patients usually have nonspecific symptoms such as unilateral hearing loss, auditory fullness, tinnitus, and otalgia. There is no specific radiological finding. A definitive diagnosis is based on complete removal of the tumor and combined histopathology and immunohistochemical examination. In this case-report, we describe a patient with MEANT who complained of hearing loss and auditory fullness in her left ear. Otomicroscopy revealed a mass of polypoid tissue filling the left external auditory canal. In the pure tone audiometry test, the pure-tone average was reported as L45/5 R10/0, and the tympanogram was type B on the left ear. In temporal bone computed tomography, the soft-tissue mass located in the middle ear was found to extend to the antrum and the external auditory canal. Biopsy taken under local anesthesia from the visible mass in the external auditory canal was reported as MEANT and the diagnosis was confirmed by histopathology and immunochemistry after surgery.

Use of Neutrophil-To-Lymphocyte and Platelet-To-Lymphocyte Ratio to Predict Early Postoperative Periorbital Edema and Ecchymosis After Primary Septorhinoplasty.

PURPOSE: To investigate the benefit of preoperative neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) in predicting early postoperative periorbital edema and ecchymosis in patients undergoing primary septorhinoplasty. METHODS: Sixty patients in ASA-I (American Society of Anesthesiologists) who were scheduled for elective primary septorhinoplasty were prospectively included in the study. Periorbital edema and ecchymosis levels of the patients were scored on the postoperative second day. The relationship between early postoperative periorbital edema and ecchymosis levels and preoperative neutrophil, lymphocyte, platelet, NLR, and PLR values were investigated. RESULTS: The mean age of the 60 patients was 24.05 ± 6.83 years. The patients were divided into 2 groups according to the total periorbital edema scores in both eyes on the second day after surgery. There was no significant difference between the two groups in terms of neutrophil, platelet, and NLR ( P > 0.05). In addition, the lymphocyte count was found to be statistically significantly lower and PLR significantly higher in the group with high edema scores ( P < 0.05). When the patients were divided into groups according to their periorbital ecchymosis scores, no significant correlation was found between any blood values and periorbital ecchymosis ( P > 0.05). CONCLUSION: Preoperative PLR may be used to predict early postoperative periorbital edema in patients undergoing primary rhinoplasty. However, a blood value that can predict periorbital ecchymosis has not been determined yet.

The association of metabolic syndrome status with sensorineural hearing loss in pediatric obese patients.

OBJECTIVES: The prevalences of pediatric obesity and its associated comorbidities such as metabolic syndrome (metS) are rising. The aim of this study was to evaluate the association of metS status with sensorineural hearing loss in pediatric obese patients. METHODS: A two-center observationalprospective study was designed. In this study, 252 consecutive treatment-naive pediatric obese patients aged 5.8-17.8 yr in a tertiary pediatric Endocrinology outpatient clinic were prospectively enrolled. Following standard clinical and biochemical evaluations, the obese patients were diagnosed as having metabolic syndrome (metS) or not according to Internetional Diabetes Federation Criteria. All the patients were evaluated with tympanometry and pure tone audiometry tests after otomicroscopic examination. Comparative analyses of audiometric evaluations were performed between metS+ and metS- subgroups of the obese patients. RESULTS: The median age of the patients was 12.5 yr (range: 6.0-17.8 yr) and 56.3% of the patients were male. Metabolic syndrome was diagnosed in 82 (32.5%) patients. Age, gender distribution, history of the ventilation tube, and pubertal stage of the metS + patients and metS- counterparts were not statistically different (p > 0.05 for all). Pure tone hearing thresholds at all frequencies (125, 250, 500, 1k, 2k, 4k, 8k) were significantly higher in the metS + group then the metS- group (p˂0.05 for all). The tympanometry results were not statistically different between the two groups (p˃0.05). Abdominal obesity, hypertension, fasting hyperglycemia and dyslipidemia were not associated with increased hearing thresholds in metS + patients (p˃0.05 for all). CONCLUSION: Metabolic syndrome was associated with increased rates of subclinical hearing loss in our cohort. None of the investigated metS components emerged as a positive association with hearing loss in our cohort. Longitudinal follow-up of our cohort may help probe the causality of the association we found.

Can Wideband Absorbance Be Used in the Detection of Ossicular Chain Defects?

Introduction: We aimed to compare the effectiveness of wideband absorbance in detecting ossicular chain discontinuity with intraoperative findings. Materials and Methods: In this study, 58 ears from 38 patients with chronic otitis media (COM) were included. Twenty-six ears with perforation and intact ossicular chain were determined as Group 1, 12 ears with perforation and ossicular chain defects were determined as Group 2, and 20 ears with normal hearing and intact tympanic membrane were determined as Group 3. The comparison of the groups was made considering the static (non-pressure) absorbance analysis performed using wideband tympanometry. Results: When perforation sites were evaluated in Group 1 and Group 2; there were 12 anterior perforations, 7 posterior perforations, and 19 subtotal perforations. Air conduction thresholds in Group 2 were significantly (P<0.05) higher than in Group 1, as expected in pure tone audiometry. When wideband absorbance (WBA) measurements were evaluated in all 3 groups, no significant difference (P>0.05) was found between the frequencies 226 to 1000 Hz. WBA measurements at 8 frequencies between 1888-2311 Hz in Group 1 were significantly lower than Group 3 (P<0.05). WBA measurements at 4 frequencies between 3462-3886 Hz frequencies in Group 2 were significantly lower than Group 1 (P<0.05). Conclusions: Our findings concluded that a significant decrease in absorbance values in the narrow frequency range may be valuable in predicting ossicular chain defects.

Identification of genetic elements required for Listeria monocytogenes growth under limited nutrient conditions and virulence by a screening of transposon insertion library.

Listeria monocytogenes, the causative agent of listeriosis, displays a lifestyle ranging from saprophytes in the soil to pathogenic as a facultative intracellular parasite in host cells. In the current study, a random transposon (Tn) insertion library was constructed in L. monocytogenes strain F2365 and screened to identify genes and pathways affecting in vitro growth and fitness in minimal medium (MM) containing different single carbohydrate as the sole carbon source. About 2,000 Tn-mutants were screened for impaired growth in MM with one of the following carbon sources: glucose, fructose, mannose, mannitol, sucrose, glycerol, and glucose 6-phosphate (G6P). Impaired or abolished growth of L. monocytogenes was observed for twenty-one Tn-mutants with disruptions in genes encoding purine biosynthesis enzymes (purL, purC, purA, and purM), pyrimidine biosynthesis proteins (pyrE and pyrC), ATP synthase (atpI and atpD2), branched-chain fatty acids (BCFA) synthesis enzyme (bkdA1), a putative lipoprotein (LMOF2365_2387 described as LP2387), dUTPase family protein (dUTPase), and two hypothetical proteins. All Tn-mutants, except the atpD2 mutant, grew as efficiently as wild-type strain in a nutrient rich media. The virulence of twenty-one Tn-mutants was assessed in mice at 72 h following intravenous (IV) infection. The most attenuated mutants had Tn insertions in purA, hypothetical protein (LMOf2365_0064 described as HP64), bkdA1, dUTPase, LP2387, and atpD2, confirming the important role of these genes in pathogenesis. Six Tn-mutants were then tested for ability to replicate intracellularly in murine macrophage J774.1 cells. Significant intracellular growth defects were observed in two Tn-mutants with insertions in purA and HP64 genes, suggesting that an intact purine biosynthesis pathway is important for intracellular growth of L. monocytogens. These findings may not be fully generalized to all of L. monocytogenes strains due to their genetic diversity. In conclusion, Tn-mutagenesis identified that biosynthesis of purines, pyrimidines, ATP, and BCFA are important for L. monocytogens pathogenesis. Purine and pyrimidine auxotrophs play an important role in the pathogenicity in other bacterial pathogens, but our study also revealed new proteins essential for both growth in MM and L. monocytogenes strain F2365 virulence.

Do the Age of Implantation, the Widths of Internal Acoustic Canal and Bony Cochlear Nerve Canal Affect the Auditory Performance of Primary School Children with Bilateral Cochlear Implants?

Objective: To reveal the correlation between implantation age, the internal acoustic canal (IAC) width, bony cochlear nerve canal (BCNC) width, and auditory performance in primary school children with bilateral cochlear implantation (CI). Methods: Preoperative IAC and BCNC widths of 57 pre-lingually deaf children aged 7-11 years who had previously undergone bilateral CI in our institution were reviewed and cut-off values were calculated. Twenty-four patients who had additional problems and could not attend school and those who refused to participate in the study were excluded. The remaining 33 were invited to the hospital, and their speech perception tests, and language development scores were analyzed (16 of 33 patients had been operated on before the age of 24 months). Results: The cut-off values calculated from the 114 ears of 57 patients were 3.86 mm for IAC width and 1.56 mm for BCNC width. The auditory performances of the 33 patients after CI were not significantly different in the narrow and normal width groups. However, speech perception test results, and language development scores of patients implanted before the age of 24 months were significantly higher. Conclusion: There are some studies showing that children with bilateral sensorineural hearing loss have narrower IAC and BCNC widths. However, we concluded that the widths of the IAC and the bone cochlear nerve canal did not affect auditory performance. We found that implantation age is the single most important determinant of speech-language development after CI.

Evaluation of Edwardsiella piscicida basS and basR mutants as vaccine candidates in catfish against edwardsiellosis.

Catfish farming is the largest aquaculture industry in the United States and an important economic driver in several southeastern states. Edwardsiella piscicida is a Gram-negative pathogen associated with significant losses in catfish aquaculture. Several Gram-negative bacteria use the BasS/BasR two-component system (TCS) to adapt to environmental changes and the host immune system. Currently, the role of BasS/BasR system in E. piscicida virulence has not been characterized. In the present study, two mutants were constructed by deleting the basS and basR genes in E. piscicida strain C07-087. Both mutant strains were characterized for virulence and immune protection in catfish hosts. The EpΔbasS and EpΔbasR mutants were more sensitive to acidic environments and produced significantly less biofilm than the wild-type. In vivo studies in channel catfish (Ictalurus punctatus) revealed that both EpΔbasS and EpΔbasR were significantly attenuated compared with the parental wild-type (3.57% and 4.17% vs. 49.16% mortalities). Moreover, there was significant protection, 95.2% and 92.3% relative percent survival (RPS), in channel catfish vaccinated with EpΔbasS and EpΔbasR against E. piscicida infection. Protection in channel catfish was associated with a significantly higher level of antibodies and upregulation of immune-related genes (IgM, IL-8 and CD8-α) in channel catfish vaccinated with EpΔbasS and EpΔbasR strains compared with non-vaccinated fish. Hybrid catfish (channel catfish ♀ × blue catfish ♂) challenges demonstrated long-term protection against subsequent challenges with E. piscicida and E. ictaluri. Our findings demonstrate BasS and BasR contribute to acid tolerance and biofilm formation, which may facilitate E. piscicida survival in harsh environments. Further, our results show that EpΔbasS and EpΔbasR mutants were safe and protective in channel catfish fingerlings, although their virulence and efficacy in hybrid catfish warrant further investigation. These data provide information regarding an important mechanism of E. piscicida virulence, and it suggests EpΔbasS and EpΔbasR strains have potential as vaccines against this emergent catfish pathogen.

How useful is electrocardiography in children with cochlear implantation?

OBJECTIVES: Hearing loss is an important health problem in children and cochlear implantation is used in its treatment. In addition, in children with hearing loss, accompanying renal, neurological, structural and cardiac conductive pathologies can often accompany. In this study, it was aimed to evaluate the electrocardiographic findings, especially QT duration in children who underwent cochlear implantation. METHODS: The data were obtained from the medical records of our hospital, which is a tertiary referral cochlear implant center. All children who had cochlear implantation surgery due to sensorineural hearing loss and admitted to our hospital for speech therapy between 2019 and 2020 were evaluated with 12-channel ECG. RESULTS: Sixty children (15 girls and 45 boys) with a mean age of 6.5 years were analyzed. Children with a history of heart disease were excluded. In cardiac examinations, five (8.3%) had systolic murmur, four (6.6%) had mid systolic click, and two (3.3%) had stiffening in the first heart sound. Abnormalities were detected in 25% (n = 15) of the electrocardiograms. The most common ECG abnormalities were prolonged QT in 4 cases, left ventricular hypertrophy in 3 cases, left axis deviation in 2 cases, and T wave changes in 2 cases. Long QT syndrome (3.3%) was diagnosed in 2 of the cases with long QT. CONCLUSION: This study demonstrates the need for electrocardiography and cardiac examinations in children undergoing cochlear implantation for hearing loss. These cases should be evaluated especially in terms of the presence of cardiac arrhythmias and potential for fatal ion channelopathy.

Spatial relation learning in complementary scenarios with deep neural networks.

A cognitive agent performing in the real world needs to learn relevant concepts about its environment (e.g., objects, color, and shapes) and react accordingly. In addition to learning the concepts, it needs to learn relations between the concepts, in particular spatial relations between objects. In this paper, we propose three approaches that allow a cognitive agent to learn spatial relations. First, using an embodied model, the agent learns to reach toward an object based on simple instructions involving left-right relations. Since the level of realism and its complexity does not permit large-scale and diverse experiences in this approach, we devise as a second approach a simple visual dataset for geometric feature learning and show that recent reasoning models can learn directional relations in different frames of reference. Yet, embodied and simple simulation approaches together still do not provide sufficient experiences. To close this gap, we thirdly propose utilizing knowledge bases for disembodied spatial relation reasoning. Since the three approaches (i.e., embodied learning, learning from simple visual data, and use of knowledge bases) are complementary, we conceptualize a cognitive architecture that combines these approaches in the context of spatial relation learning.

Long-Term Effects of Metal-on-Metal Cobalt-Chromium-Containing Prostheses Used in Total Knee Arthroplasty on Hearing and Tinnitus.

Objectives: We aimed to determine the long-term effects of metal-on-metal (MoM) cobalt (Co)-chromium-containing prostheses used in total knee arthroplasty (TKA) on hearing and tinnitus. Methods: A total of 88 patients with the normal otoscopic examination and normal blood B12 levels, consisting of 44 patients who had been using MoM Co-chromium-containing total knee prosthesis for more than 5 years, and 44 non-implanted patients with similar demographic characteristics, were randomly selected and included in the study. Patients with previous ear surgery, chronic middle ear disease, or conductive hearing loss were excluded from the study. All participants were evaluated with pure-tone audiometry (PTA), distortion product otoacoustic emission (DPOAE), tinnitus handicap inventory (THI), and tinnitus reaction questionnaire (TRQ). Results: The mean age of the 88 patients was 67.22±10.4 years. The mean age of 44 patients who underwent TKA at least 5 years ago was 72.89±7.18 years, 75% of these patients had bilateral prostheses, and the mean prosthesis duration was 11.00±5.08 years (range 5-25). The two groups were compared statistically using PTA, DPOAE, THI, and TRQ scores. When the patient groups with and without prostheses were compared in terms of hearing and tinnitus, we did not find a significant difference between the two groups (p>0.05). Conclusion: In our study, we observed that the long-term use of MoM Co-chromium total knee prostheses did not have an ototoxic effect, contrary to what was believed. We also found that prolonged prosthesis duration or undergoing bilateral surgery did not worsen hearing and tinnitus.

Thermal Characteristics of Different Types of Cochlear Implants in Pediatric Cochlear Implant Users: AComparative Digital-Infrared Thermal Imaging Analysis.

BACKGROUND: This study aimed to evaluate thermal characteristics of different types of pediatric cochlear implants METHODS: A total of 39 pediatric patients using Med-El (Synchrony®), Cochlear (Nucleus®), or Advanced Bionics (HiRes 90K®) type of cochlear implants were included. A digital infrared thermal imaging analysis was performed to measure the heating over the implant and the tissue heat- ing of the skin below and around the device, while skin thickness and visual analog scale scores were also recorded. RESULTS: Over the implant, heating values were significantly higher in the on-mode vs. off-mode of device for each type of implant (P ranged from <.05 to <.001). The implants groups were similar in terms of skin thickness, visual analog scale scores, on-mode values for heating over the implant, and the heating of the skin (below or around the device; <36°C for each), while the off-mode values for heating over the implant were significantly higher in the Med-El (Synchrony®) implants compared to other implants (median 31.75 vs. 31.30 and 30.20°C, P = .001). Skin thick- ness was negatively correlated with the heating over the implant (off-mode, r=-0.708, P < .001) and heating of the skin (around the device, r = -0.479, P = .028) in Advanced Bionics (HiRes 90K®) implants. CONCLUSION: Our findings emphasize that there is no hazard or discomfort from a cochlear implant in terms of heating of skin and no significant difference between 3 implant types in terms of skin thickness or tissue heating, whereas indicate the increased likelihood of thermal characteris- tics of implant to differ with respect to skin thickness in Advanced Bionics (HiRes 90K®) users.

Cochlear Implant Complications in a Tertiary Referral Center in Istanbul.

OBJECTIVE: All surgeons should inform the patients about complications and also their clinic's complication rates of cochlear implantation (CI). We aimed to review the complications of CI in 1,148 pediatric and adult patients. METHODS: It is a retrospective case review study enrolled in a tertiary referral center in Istanbul where CI was mostly performed. A total of 1,148 pediatric and adult CIs (unilateral or bilateral CI and revision surgery) performed by the same experienced surgeon in our institution were examined. Complications were noted as major and minor. RESULTS: The mean age of first CI of 702 children and 157 adult patients was 10.2 years (1-75 years). The overall complication rate was 13.68%, comprising 8.28% of minor and 5.4% of major complications. Swelling (wound seroma or hematoma) was the most common minor complication. The most common cause of major complications was related to implanted devices. Despite the high rates of minor complications in children, there was no statistically significant difference between children and adults (p = 0,194). CONCLUSIONS: Our clinic has a low major complication rate. Surgeons should be aware of postoperative complications, apply appropriate procedures, and inform patients about their surgical complication rates.

The Embodied Crossmodal Self Forms Language and Interaction: A Computational Cognitive Review.

Human language is inherently embodied and grounded in sensorimotor representations of the self and the world around it. This suggests that the body schema and ideomotor action-effect associations play an important role in language understanding, language generation, and verbal/physical interaction with others. There are computational models that focus purely on non-verbal interaction between humans and robots, and there are computational models for dialog systems that focus only on verbal interaction. However, there is a lack of research that integrates these approaches. We hypothesize that the development of computational models of the self is very appropriate for considering joint verbal and physical interaction. Therefore, they provide the substantial potential to foster the psychological and cognitive understanding of language grounding, and they have significant potential to improve human-robot interaction methods and applications. This review is a first step toward developing models of the self that integrate verbal and non-verbal communication. To this end, we first analyze the relevant findings and mechanisms for language grounding in the psychological and cognitive literature on ideomotor theory. Second, we identify the existing computational methods that implement physical decision-making and verbal interaction. As a result, we outline how the current computational methods can be used to create advanced computational interaction models that integrate language grounding with body schemas and self-representations.

Virulence and live vaccine potential of Edwardsiella piscicida phoP and phoQ mutants in catfish against edwardsiellosis.

Edwardsiella piscicida is a Gram-negative facultative intracellular bacterium causing edwardsiellosis in catfish, the largest aquaculture industry in the United States. A safe and effective vaccine is an urgent need to avoid economic losses associated with E. piscicida outbreaks. PhoP/PhoQ is a two-component signal transduction system (TCS) that plays an important role in bacterial pathogenesis through sense and response to environmental and host stress signals. This study aimed to explore the contribution of PhoQ/PhoP in E. piscicida virulence and develop live attenuated vaccines against E. piscicida infection in channel catfish (Ictalurus punctatus) and hybrid catfish (channel catfish ♀ × blue catfish (I. furcatus) ♂). In the current study, two in-frame deletion mutants were constructed by deleting phoP (ETAC_09785) and phoQ (ETAC_09790) genes in E. piscicida strain C07-087, and the virulence and protection efficacy of the constructed strains were evaluated in catfish following intraperitoneal injection. Both EpΔphoP and EpΔphoQ strains had a delayed adaptation to oxidative stress (0.2% H2 O2 ) compared to E. piscicida wild type. The EpΔphoP and EpΔphoQ mutants produced significantly less biofilm compared to wild-type E. piscicida. Notably, EpΔphoP and EpΔphoQ mutants were significantly attenuated in channel catfish compared with wild-type E. piscicida (6.63% and 4.17% versus 49.16% mortalities), and channel catfish vaccinated with EpΔphoP and EpΔphoQ were significantly protected (95.65% and 97.92% survival) against E. piscicida infection at 21 days post-vaccination. In hybrid catfish, EpΔphoP was significantly more attenuated than EpΔphoQ, but EpΔphoQ provided significantly better protection than EpΔphoP. EpΔphoP and EpΔphoQ strains both induced specific antibodies in channel catfish against E. piscicida at 14 and 21 days post-vaccination. This result indicated that EpΔphoP and EpΔphoQ mutants were safe and protective in channel catfish fingerlings, while EpΔphoP was safe in hybrid catfish. Our findings show that PhoP and PhoQ are required for adaptation to oxidative stress and biofilm formation and may help E. piscicida face tough environmental challenges; thus, functional PhoP and PhoQ are critical for a successful infection.

Cleft Palate Patient With Conductive Hearing Loss Due to Stapes Fixation.

Congenital stapes fixation is characterized by congenital conductive hearing loss that is not progressive. This rare disease may be accompanied by additional middle ear anomalies. However, the occurrence of congenital stapes fixation with cleft palate and oligodontia was described by Gorlin et al. in 1973, and no further cases have been reported in the literature. Congenital stapes fixation was detected after the exploratory tympanotomy operation performed on a 15-year-old male patient admitted to our clinic with hearing loss, more prominent on the left. The patient also had a previous operation due to cleft lip and had congenital deficiencies in the upper and lower teeth. We present the second case report in the literature which we think belongs to this syndrome, which is defined as cleft palate, stapes fixation, and oligodontia syndrome by Gorlin et al. Laryngoscope, 131:E1279-E1281, 2021.

Contributions of a LysR Transcriptional Regulator to Listeria monocytogenes Virulence and Identification of Its Regulons.

The capacity of Listeria monocytogenes to adapt to environmental changes is facilitated by a large number of regulatory proteins encoded by its genome. Among these proteins are the uncharacterized LysR-type transcriptional regulators (LTTRs). LTTRs can work as positive and/or negative transcription regulators at both local and global genetic levels. Previously, our group determined by comparative genome analysis that one member of the LTTRs (NCBI accession no. WP_003734782) was present in pathogenic strains but absent from nonpathogenic strains. The goal of the present study was to assess the importance of this transcription factor in the virulence of L. monocytogenes strain F2365 and to identify its regulons. An L. monocytogenes strain lacking lysR (the F2365ΔlysR strain) displayed significant reductions in cell invasion of and adhesion to Caco-2 cells. In plaque assays, the deletion of lysR resulted in a 42.86% decrease in plaque number and a 13.48% decrease in average plaque size. Furthermore, the deletion of lysR also attenuated the virulence of L. monocytogenes in mice following oral and intraperitoneal inoculation. The analysis of transcriptomics revealed that the transcript levels of 139 genes were upregulated, while 113 genes were downregulated in the F2365ΔlysR strain compared to levels in the wild-type bacteria. lysR-repressed genes included ABC transporters, important for starch and sucrose metabolism as well as glycerolipid metabolism, flagellar assembly, quorum sensing, and glycolysis/gluconeogenesis. Conversely, lysR activated the expression of genes related to fructose and mannose metabolism, cationic antimicrobial peptide (CAMP) resistance, and beta-lactam resistance. These data suggested that lysR contributed to L. monocytogenes virulence by broad impact on multiple pathways of gene expression.IMPORTANCEListeria monocytogenes is the causative agent of listeriosis, an infectious and fatal disease of animals and humans. In this study, we have shown that lysR contributes to Listeria pathogenesis and replication in cell lines. We also highlight the importance of lysR in regulating the transcription of genes involved in different pathways that might be essential for the growth and persistence of L. monocytogenes in the host or under nutrient limitation. Better understanding L. monocytogenes pathogenesis and the role of various virulence factors is necessary for further development of prevention and control strategies.

An Edwardsiella piscicida esaS mutant reveals contribution to virulence and vaccine potential.

Edwardsiella piscicida is a Gram-negative pathogen that causes disease in diverse aquatic organisms. The disease leads to extensive losses in commercial aquaculture species, including farmed U.S. catfish. The type III secretion system (T3SS) often contributes to virulence of Gram-negative bacteria. The E. piscicida esaS gene encodes a predicted T3SS export apparatus protein. In the current study, an E. piscicida esaS mutant was constructed and characterized to increase our understanding of the role of T3SS in E. piscicida virulence. Deletion of esaS did not significantly affect biofilm formation and hemolytic activity of E. piscicida, but it had significant effects on expression of hemolysis and T3SS effector genes during biofilm growth. EpΔesaS showed significantly (P < 0.05) reduced virulence in catfish compared to the parent strain. No mortalities occurred in fish infected with EpΔesaS at 6.3 × 105 and 1.26 × 106 CFU/fish compared to 26% mortality in fish infected with wild-type E. piscicida at 7.5 × 105 CFU/fish. Bioluminescence imaging indicated that EpΔesaS invades catfish and colonizes for a short period in the organs. Furthermore, catfish immunized with EpΔesaS at 6.3 × 105 and 1.26 × 106 CFU provided 47% and 87% relative percent survival, respectively. These findings demonstrated that esaS plays a role in E. piscicida virulence, and the deletion mutant has vaccine potential for protection against wild-type E. piscicida infection.