Helicobacter pylori-Induced Decrease in Membrane Expression of Na,K-ATPase Leads to Gastric Injury.

Helicobacter pylori is a highly prevalent human gastric pathogen that causes gastritis, ulcer disease, and gastric cancer. It is not yet fully understood how H. pylori injures the gastric epithelium. The Na,K-ATPase, an essential transporter found in virtually all mammalian cells, has been shown to be important for maintaining the barrier function of lung and kidney epithelia. H. pylori decreases levels of Na,K-ATPase in the plasma membrane of gastric epithelial cells, and the aim of this study was to demonstrate that this reduction led to gastric injury by impairing the epithelial barrier. Similar to H. pylori infection, the inhibition of Na,K-ATPase with ouabain decreased transepithelial electrical resistance and increased paracellular permeability in cell monolayers of human gastric cultured cells, 2D human gastric organoids, and gastric epithelium isolated from gerbils. Similar effects were caused by a partial shRNA silencing of Na,K-ATPase in human gastric organoids. Both H. pylori infection and ouabain exposure disrupted organization of adherens junctions in human gastric epithelia as demonstrated by E-cadherin immunofluorescence. Functional and structural impairment of epithelial integrity with a decrease in Na,K-ATPase amount or activity provides evidence that the H. pylori-induced downregulation of Na,K-ATPase plays a role in the complex mechanism of gastric disease induced by the bacteria.

Intestinal Re-Transplantation.

The history of intestinal transplantation can be traced back to the turn of the twentieth century. Although advancements have been made, the intestine still presents a greater challenge to transplantation than does that of other solid organs, experiencing higher rates of graft rejection and lower long-term survival. Increasingly, intestinal re-transplantation (re-ITx) is seen as a viable option and is now the fourth most common indication for ITx. Changes to immunosuppression protocols, technical modifications, and infectious disease monitoring have contributed to improved outcomes. The authors review the literature on re-ITx in regard to the history, management considerations, and future directions.

Treatment of an Adolescent Female With Nonalcoholic Steatohepatitis-Related Cirrhosis With Liraglutide.

Nonalcoholic fatty liver disease is the most common chronic liver disease in children in the United States and encompasses a range of disease from steatosis to cirrhosis. The mainstay of treatment is lifestyle modifications like increased physical activity and healthier eating habits. These are sometimes augmented with medications or surgery for weight loss. We present a patient with biopsy-proven nonalcoholic steatohepatitis-related cirrhosis that did not improve with suboptimal lifestyle changes. This patient's disease progression reversed after liraglutide treatment, as evidenced by improved imaging and laboratory results, despite no significant improvement in her body mass index percentile. This case demonstrates the importance of considering liraglutide for patients with nonalcoholic steatohepatitis and suggests a hepatic effect independent of effects related to weight loss.

REG3α is a novel biomarker that potentially correlates with acute allograft rejection after intestinal transplantation.

Monitoring of intestinal allograft function remains a challenge. While frequent endoscopies and biopsies are the gold standard, no single biomarker exists to screen for intestinal transplant rejection. The novel REG3α, an antimicrobial peptide secreted by intestinal enterocytes and Paneth cells, has been associated with inflammatory bowel disease as well as intestinal graft versus host disease. Our aim was to identify and describe a role of REG3α in monitoring or predicting acute allograft rejection after intestinal transplantation (ITx). Since 2019, we have incorporated REG3α into the standard monitoring of patients after ITx. We conducted a retrospective analysis of a prospectively maintained IRB-approved database and present, herein, the results of 2 adults with irreversible intestinal failure who underwent isolated ITx under this monitoring protocol. Increases in REG3α corresponded with acute allograft rejection in both cases and preceded acute allograft rejection by 1 week in one of the cases. We describe REG3α as a non-invasive marker of acute allograft rejection after adult isolated ITx which not only corresponded with acute allograft rejection but also preceded histopathological changes by 1 week.

Non-HLA AT1R antibodies are highly prevalent after pediatric intestinal transplantation.

The role of angiotensin II type-1 receptor (AT1R) antibodies in intestinal transplantation (ITx) is unclear. The aims were 1) to identify the prevalence of AT1R antibodies in pediatric ITx, compared to pediatric intestinal failure (IF), and 2) to determine whether AT1R antibodies were associated with graft dysfunction. 46 serum samples from 25 ITx patients (3 isolated ITx, 22 liver-inclusive ITx) were collected during routine visits >6 months apart and during episodes of graft dysfunction as a result of infectious enteritis or rejection. For comparison, samples were collected from 7 IF control patients. AT1R antibodies were considered positive for levels >17 U/mL. The median (range) AT1R antibody level for ITx patients was 40.0 U/mL (7.2-40.0), compared to 7.0 U/mL (5.7-40.0) for IF patients (p = .02). There was a trend toward higher prevalence of AT1R antibodies in ITx compared with IF patients (68% versus 29%, p = .09). Among ITx patients, the prevalence of AT1R antibodies was not different between periods of active graft dysfunction and normal health (83% versus 67%, p = .31). For 16 patients with >2 samples, AT1R antibodies remained positive in 67% cases, developed in 14% cases, disappeared in 10% cases, and remained negative in 10% cases. The changes in AT1R antibodies did not correlate with de/sensitizing events. This is the first study of AT1R antibodies in pediatric ITx. AT1R antibodies are highly prevalent after ITx and may be triggered by immune activation associated with the transplant. However, their pathogenicity and clinical utility remain in question.

Prognostic and predictive value of circulating tumor DNA during neoadjuvant chemotherapy for triple negative breast cancer.

Response to neoadjuvant chemotherapy (NAC) in triple negative breast cancer (TNBC) is highly prognostic and determines whether adjuvant chemotherapy is needed if residual tumor is found at surgery. To evaluate the predictive and prognostic values of circulating tumor DNA (ctDNA) in this setting, we analyzed tumor and serial bloods from 26 TNBC patients collected prior, during, and after NAC. Individual digital droplet PCR assays were developed for 121 variants (average 5/patient) identified from tumor sequencing, enabling ctDNA detection in 96% of patients at baseline. Mutant allele frequency at baseline was associated with clinical characteristics. Levels drastically fell after one cycle of NAC, especially in patients whose tumors would go on to have a pathological complete response (pCR), but then rose significantly before surgery in patients with significant residual tumor at surgery (p = 0.0001). The detection of ctDNA early during treatment and also late at the end of NAC before surgery was strongly predictive of residual tumor at surgery, but its absence was less predictive of pCR, especially when only TP53 variants are considered. ctDNA detection at the end of neoadjuvant chemotherapy indicated significantly worse relapse-free survival (HR = 0.29 (95% CI 0.08-0.98), p = 0.046), and overall survival (HR = 0.27 95% CI 0.075-0.96), p = 0.043). Hence, individualized multi-variant ctDNA testing during and after NAC prior to surgery has prognostic and predictive value in early TNBC patients.

Helicobacter pylori infection impairs chaperone-assisted maturation of Na-K-ATPase in gastric epithelium.

Helicobacter pylori infection always induces gastritis, which may progress to ulcer disease or cancer. The mechanisms underlying mucosal injury by the bacteria are incompletely understood. Here, we identify a novel pathway for H. pylori-induced gastric injury, the impairment of maturation of the essential transport enzyme and cell adhesion molecule, Na-K-ATPase. Na-K-ATPase comprises α- and ß-subunits that assemble in the endoplasmic reticulum (ER) before trafficking to the plasma membrane. Attachment of H. pylori to gastric epithelial cells increased Na-K-ATPase ubiquitylation, decreased its surface and total levels, and impaired ion balance. H. pylori did not alter degradation of plasmalemma-resident Na-K-ATPase subunits or their mRNA levels. Infection decreased association of α- and ß-subunits with ER chaperone BiP and impaired assembly of α/ß-heterodimers, as was revealed by quantitative mass spectrometry and immunoblotting of immunoprecipitated complexes. The total level of BiP was not altered, and the decrease in interaction with BiP was not observed for other BiP client proteins. The H. pylori-induced decrease in Na-K-ATPase was prevented by BiP overexpression, stopping protein synthesis, or inhibiting proteasomal, but not lysosomal, protein degradation. The results indicate that H. pylori impairs chaperone-assisted maturation of newly made Na-K-ATPase subunits in the ER independently of a generalized ER stress and induces their ubiquitylation and proteasomal degradation. The decrease in Na-K-ATPase levels is also seen in vivo in the stomachs of gerbils and chronically infected children. Further understanding of H. pylori-induced Na-K-ATPase degradation will provide insights for protection against advanced disease.NEW & NOTEWORTHY This work provides evidence that Helicobacter pylori decreases levels of Na-K-ATPase, a vital transport enzyme, in gastric epithelia, both in acutely infected cultured cells and in chronically infected patients and animals. The bacteria interfere with BiP-assisted folding of newly-made Na-K-ATPase subunits in the endoplasmic reticulum, accelerating their ubiquitylation and proteasomal degradation and decreasing efficiency of the assembly of native enzyme. Decreased Na-K-ATPase expression contributes to H. pylori-induced gastric injury.

Ileostomy After Intestinal Transplantation: The First in Depth Report on Techniques, Complications, and Outcomes.

BACKGROUND: Temporary ileostomy during intestinal transplantation (ITx) is the standard technique for allograft monitoring. A detailed analysis of the ITx ileostomy has never been reported. METHODS: A retrospective review of a single-center ITx database was performed. The analysis was divided into ileostomy formation and takedown episodes. RESULTS: One hundred thirty-five grafts underwent ileostomy formation, and 79 underwent ileostomy takedown. Median age at ITx was 7.7 years and weight was 23 kg. Allograft types were intestine (22%), liver/intestine (55%), multivisceral (16%), and modified multivisceral (7%). Sixty-four percent had 1-stage ITx, whereas 36% required 2-staged ITx. Final ileostomy types were end (20%), loop (10%), distal blowhole (59%), and proximal blowhole (11%). Ileostomy formation: Thirty-one grafts had complications (23%), including prolapse (26%), ischemia (16%), and parastomal hernia (19%). Twelve required surgical revision. There were no significant differences in graft type, ileostomy type, survival, and ileostomy takedown rate between grafts with and without complications. Colon inclusive grafts had higher complication rates (P = 0.002). Ileostomy takedown: Ileostomy takedown occurred at a median of 422 days post-ITx. Twenty-five complications occurred after 22 takedowns (28%), including small bowel obstruction (27%) and abscess (18%). Fifteen grafts required surgical correction. Recipients with complications had longer hospital stay (17 versus 9 d; P = 0.001) than those without complications. Graft type, ileostomy type, and survival were not different. CONCLUSIONS: The first of its kind analysis of the surgical ileostomy after ITx reveals that most recipients can undergo successful ileostomy formation/takedown, complication rates are significant but within an acceptable range, and complications do not affect survival. This study demonstrates that the routine use of transplant ostomies remains an acceptable practice after ITx. However, true analysis of risk and benefit will require a randomized control trial.

A Unique Morphological Phenotype in Chemoresistant Triple-Negative Breast Cancer Reveals Metabolic Reprogramming and PLIN4 Expression as a Molecular Vulnerability.

The major obstacle in successfully treating triple-negative breast cancer (TNBC) is resistance to cytotoxic chemotherapy, the mainstay of treatment in this disease. Previous preclinical models of chemoresistance in TNBC have suffered from a lack of clinical relevance. Using a single high dose chemotherapy treatment, we developed a novel MDA-MB-436 cell-based model of chemoresistance characterized by a unique and complex morphologic phenotype, which consists of polyploid giant cancer cells giving rise to neuron-like mononuclear daughter cells filled with smaller but functional mitochondria and numerous lipid droplets. This resistant phenotype is associated with metabolic reprogramming with a shift to a greater dependence on fatty acids and oxidative phosphorylation. We validated both the molecular and histologic features of this model in a clinical cohort of primary chemoresistant TNBCs and identified several metabolic vulnerabilities including a dependence on PLIN4, a perilipin coating the observed lipid droplets, expressed both in the TNBC-resistant cells and clinical chemoresistant tumors treated with neoadjuvant doxorubicin-based chemotherapy. These findings thus reveal a novel mechanism of chemotherapy resistance that has therapeutic implications in the treatment of drug-resistant cancer. IMPLICATIONS: These findings underlie the importance of a novel morphologic-metabolic phenotype associated with chemotherapy resistance in TNBC, and bring to light novel therapeutic targets resulting from vulnerabilities in this phenotype, including the expression of PLIN4 essential for stabilizing lipid droplets in resistant cells.

Assessing the Impact of CALGB 9343 on Surgical Trends in Elderly-Women With Stage I ER+ Breast Cancer: A SEER-Based Analysis.

Purpose: Lumpectomy (L) and breast radiotherapy (RT) results in equivalent outcomes in comparison to mastectomy (M) for early-stage breast cancer (BC) based on randomized controlled trials (RCT). Since 2004, RCT support that L without RT yields equivalent survival and acceptable local-regional outcomes in women ≥70-years old with T1N0 hormone-sensitive (ER+) BC on endocrine therapy. Based on this, we hypothesized that M rates should decrease substantially after 2004 in this low-risk elderly population. Methods: We used the Surveillance Epidemiology and End Results registry data to conduct this study. We included women with T1N0 ER+ BC from 2000 to 2014. We compared M rates in women diagnosed from 2000 to 2004 vs. 2005-2012 using the Chi-Square test. Logistic regression analyses was performed to examine demographic/clinical factors associated with mastectomy. Results: 67,506 women met the study criteria. In elderly Stage I ER+ BC, the M rate decreased by 6.3%: 29.0% before 2004 to 22.7% after 2004 (p < 0.0001). M rates remained higher in elderly non-Hispanic black (NHB, 27.1%, p < 0.0001), non-Hispanic Asian-Pacific-Islander (NHAPI, 30.1%, p < 0.0001), and Hispanics (24.4%, p = 0.0004) vs. non-Hispanic White (NHW, 21.5%). Treatment in the modern cohort was associated with decreased odds of mastectomy (OR = 0.71, 95% CI 0.68-0.74, p < 0.0001) while NH-API race was associated with the highest increased odds of mastectomy (OR = 1.65, 95% 1.53-1.78, p < 0.0001). In the modern cohort specifically (2005-2014), Hispanic women (OR = 1.12, p = 0.014), NHB women (OR = 1.21, p < 0.0001), and NHAPI women (OR = 1.73, p < 0.0001) all had higher odds of undergoing mastectomy relative to NHW women after adjusting for all other patient and tumor related factors. Conclusions: In elderly patients with stage I, ER+ BC, M rates have decreased modestly since 2004. These trends are driven mostly be decreases in the M rate in NHW women, but M rates remain ~25% in Hispanic, NHB, and NHAPI women. Further research is needed to identify why M, which is associated with higher cost and morbidity than L alone, has not changed substantially in elderly, low-risk BC.

Intestinal failure after bariatric surgery: Treatment and outcome at a single-intestinal rehabilitation and transplant center.

BACKGROUND: Though intestinal failure (IF) after bariatric surgery (BS) is uncommon, its prevalence is increasing. However, data on the outcomes for these patients are limited. OBJECTIVES: To analyze the outcomes of treatment for patients with IF after BS. SETTING: University hospital. METHODS: A single-center analysis (1991-2016) of outcomes according to treatment arms established by a multidisciplinary team. RESULTS: Twenty-five IF patients were identified (median age 45 yr). BS was 92% Roux-en-Y gastric bypass. The major cause of IF was volvulus/internal hernia (72%). Median time from BS to IF was 48 months. Treatment arms were intestinal rehabilitation (IR, n = 15), transplantation (TXP, n = 5), and parenteral nutrition (PN, n = 5). For IR, median bowel length was 60 cm. Forty-six percent ultimately discontinued PN. Twenty-seven percent were partially weaned PN and 27% failed IR. Common surgical rehabilitation was Roux-en-Y gastric bypass reversal and restoration of gastrointestinal continuity. The 5-year overall survival was 74%. For TXP, 7 patients were listed for TXP (5 initially and 2 after failed IR). Three underwent TXP, 2 isolated intestine and 1 isolated liver. Three were delisted (1 improvement and 2 death). For PN, 6 patients required long-term PN (5 initially and 1 after failed IR). Four patients are alive currently. CONCLUSIONS: IF after BS is an increasing problem facing IR centers. Internal hernia is the major cause. Surgical IR is the first-line therapy and affords the best outcome. TXP is reserved for rescuing patients who failed IR or develop PN complications. Long-term PN is suitable for patients in whom IR or TXP is impractical.

Central venous catheter repair is highly successful in children with intestinal failure.

PURPOSE: Damaged central venous catheters (CVCs) are commonly repaired to avoid line replacement and preserve vascular access. However, limited data suggest an increased risk for central line-associated bloodstream infections (CLABSIs) associated with the repair procedure. The purpose of this study was to describe outcomes of CVC repairs among parenteral nutrition (PN) dependent children with intestinal failure (IF). METHODS: A 2-year retrospective review was performed on children with IF on home PN > 6 months. Outcomes of interest were repair success and postrepair CLABSI incidence. Descriptive statistics included medians and frequencies. RESULTS: A total of 36 pediatric IF patients underwent 96 CVC repairs during the study period. The median CVC repair count was 1.5 repairs/patient (range, 1 to 16 repairs/patient) with >1 repair in half the patients. Ninety-four broken catheters (98%) were successfully repaired with restoration of function. Of the unsuccessful repairs (2%), the two catheters eventually required surgical removal and replacement. One repair (1%) was followed by a CLABSI with Enterococcus faecalis in an immunocompromised patient. CONCLUSION: CVC repair is a highly successful procedure with a low risk for infection. Catheter repair should be considered whenever possible as it may extend the lifetime of the catheter and decrease the risk for vascular access loss. LEVEL OF EVIDENCE: Treatment study; level IV.

Esophageal IgG4: Clinical, Endoscopic, and Histologic Correlations in Eosinophilic Esophagitis.

OBJECTIVE: Recent studies show increased serum and esophageal IgG4 in patients with eosinophilic esophagitis (EoE), suggesting a possible IgG4-involved process. The role of IgG4 in pediatric EoE has not been extensively investigated. Our aim was to analyze IgG4 in esophageal tissue in children in parallel to that in adults with EoE. METHODS: In a retrospective institutional review board-approved study, we performed immunohistochemical staining of IgG4 in esophageal biopsy specimens from 39 subjects: children with EoE (n = 16), adults with EoE (n = 15), children with reflux esophagitis (n = 4), and pediatric controls (n = 4). We assessed the relationships between IgG4 staining and clinical, endoscopic, and histopathologic characteristics. RESULTS: Patients with EoE were significantly more likely to stain positively for IgG4 than children with reflux esophagitis or controls (P = 0.015). Fifteen of 31 (48%) EoE cases stained positively for IgG4. None of the reflux esophagitis or control cases stained positively. IgG4 staining had 48% sensitivity and 100% specificity for EoE. There was a trend toward IgG4 staining being associated with foreign body/food impaction (P = 0.153). There was a strong association between distal IgG4 staining and basal zone hyperplasia (P = 0.003). CONCLUSIONS: Our study suggests IgG4 is not a consistent finding of EoE at disease diagnosis. Although IgG4 staining was specific for EoE, it had a poor sensitivity with positive staining in only 48% of EoE patients. Further studies are warranted to fully elucidate the role of IgG4 in EoE.

Characterization of T cell immunophenotypes in intestinal transplantation: A pilot study.

Immunophenotyping of peripheral blood mononuclear cells has been shown to be a useful, non-invasive method of predicting acute cellular rejection (ACR) following intestinal transplantation (ITx). Our objectives were to characterize differences in the T cell immunophenotype of ITx recipients in peripheral blood samples (1) collected late versus early after ITx and (1) associated with episodes of ACR and infectious enteritis. An IRB-approved, cross-sectional study of ITx recipients was performed. Peripheral blood samples were collected during normal visits and episodes of allograft dysfunction. A total of 38 patients were included in the analysis: 31 ITx recipients (87% liver-inclusive allografts) and 7 intestinal failure control patients. Of the ITx patients, 26 patients were pediatric patients (<21 years). A total of 70 samples were analyzed from ITx recipients, including 51 during normal visits and 19 during episodes of allograft dysfunction (median of 2 samples per patient; range of 1-6 samples per patient). In the late (n = 32) versus early post-ITx (n = 19) normal samples, there was a significantly higher percentage of central memory CD4 T cells (p = .001). In the ACR (n = 5) versus infectious enteritis (n = 14) samples, there was a higher percentage of CD8 T cells expressing HLA-DR (p = .002), CD57 (p < .001), and KLRG1 (p < .001) and a higher percentage of CD4 T cells expressing CD57 (p = .03). Additional studies are needed with larger cohorts to validate these changes in the T cell immunophenotype. Further elucidating T cell immunophenotypes in ITx will lead to a better understanding of immune mechanisms of allograft dysfunction, identification of potential biomarkers in ITx, and optimized selection of immunosuppressive therapies.

Clinical characteristics and outcomes of PTLD following intestinal transplantation.

Post-transplant lymphoproliferative disease (PTLD) has the highest incidence following intestinal transplantation (ITx). Our center has seen a recent increase in PTLD. Our aim was to review a single-center PTLD experience with a focus on clinical characteristics and outcomes. We completed a retrospective review of biopsy-proven PTLD cases using a prospectively maintained database of 115 ITx recipients transplanted between 1991 and 2014. Nineteen (17%) ITx recipients developed 25 PTLD cases during a median follow-up time of 6.4 (1.6-14.6) years. The incidence of early PTLD was 6% (n = 7). There was a trend toward increased risk of PTLD in children compared with adults (P = .11) and a significantly increased risk of PTLD in re-ITx compared with primary ITx recipients (P = .03). Most PTLD cases were diagnosed between 2010 and 2014 (n = 14). All early PTLD cases were EBV+ on in situ hybridization. Overall graft and patient survival are 68% and 74%, respectively. Second episodes of PTLD were diagnosed in 43% of surviving pediatric patients. Our program has a low incidence of early PTLD with overall excellent graft and patient survival following diagnosis. However, we have also seen a rising incidence of late PTLD. The cause of the increase is unknown as no major changes in immunosuppression protocols have occurred since 1999.

Measurement of Internal pH in Helicobacter pylori by Using Green Fluorescent Protein Fluorimetry.

Helicobacter pylori is an organism known to colonize the normal human stomach. Previous studies have shown that the bacterium does this by elevating its periplasmic pH via the hydrolysis of urea. However, the value of the periplasmic pH was calculated indirectly from the proton motive force equation. To measure the periplasmic pH directly in H. pylori, we fused enhanced green fluorescent protein (EGFP) to the predicted twin-arginine signal peptides of HydA and KapA from H. pylori and TorA from Escherichia coli The fusion proteins were expressed in the H. pylori genome under the control of the cagA promoter. Confocal microscopic and cell fractionation/immunoblotting analyses detected TorA-EGFP in the periplasm and KapA-EGFP in both the periplasm and cytoplasm, while the mature form of HydA-EGFP was seen at low levels in the periplasm, with major cytoplasmic retention of the precursor form. With H. pylori expressing TorA-EGFP, we established a system to directly measure periplasmic pH based on the pH-sensitive fluorimetry of EGFP. These measurements demonstrated that the addition of 5 mM urea has little effect on the periplasmic pH at a medium pH higher than pH 6.5 but rapidly increases the periplasmic pH to pH 6.1 at an acidic medium pH (pH 5.0), corresponding to the opening of the proton-gated channel, UreI, and confirming the basis of gastric colonization. Measurements of the periplasmic pH in an HP0244 (FlgS)-deficient mutant of H. pylori expressing TorA-EGFP revealed a significant loss of the urea-dependent increase in the periplasmic pH at an acidic medium pH, providing additional evidence that FlgS is responsible for recruitment of urease to the inner membrane in association with UreI.IMPORTANCEHelicobacter pylori has been identified as the major cause of chronic superficial gastritis and peptic ulcer disease. In addition, persistent infection with H. pylori, which, if untreated, lasts for the lifetime of an infected individual, predisposes one to gastric malignancies, such as adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. A unique feature of the neutralophilic bacterium H. pylori is its ability to survive in the extremely acidic environment of the stomach through its acid acclimation mechanism. The presented results on measurements of periplasmic pH in H. pylori based on fluorimetry of fully active green fluorescent protein fusion proteins exported with the twin-arginine translocase system provide a reliable and rapid tool for the investigation of acid acclimation in H. pylori.

Acid-regulated gene expression of Helicobacter pylori: Insight into acid protection and gastric colonization.

BACKGROUND: The pathogen Helicobacter pylori encounters many stressors as it transits to and infects the gastric epithelium. Gastric acidity is the predominate stressor encountered by the bacterium during initial infection and establishment of persistent infection. H. pylori initiates a rapid response to acid to maintain intracellular pH and proton motive force appropriate for a neutralophile. However, acid sensing by H. pylori may also serve as a transcriptional trigger to increase the levels of other pathogenic factors needed to subvert host defenses such as acid acclimation, antioxidants, flagellar synthesis and assembly, and CagA secretion. MATERIALS AND METHODS: Helicobacter pylori were acid challenged at pH 3.0, 4.5, 6.0 vs nonacidic pH for 4 hours in the presence of urea, followed by RNA-seq analysis and qPCR. Cytoplasmic pH was monitored under the same conditions. RESULTS: About 250 genes were induced, and an equal number were repressed at acidic pHs. Genes encoding for antioxidant proteins, flagellar structural proteins, particularly class 2 genes, T4SS/Cag-PAI, Fo F1 -ATPase, and proteins involved in acid acclimation were highly expressed at acidic pH. Cytoplasmic pH decreased from 7.8 at pHout of 8.0 to 6.0 at pHout of 3.0. CONCLUSIONS: These results suggest that increasing extracellular or intracellular acidity or both are detected by the bacterium and serve as a signal to initiate increased production of protective and pathogenic factors needed to counter host defenses for persistent infection. These changes are dependent on degree of acidity and time of acid exposure, triggering a coordinated response to the environment required for colonization.

Epidemiology and Risk Factors for Outpatient-Acquired Catheter-Related Bloodstream Infections in Children Receiving Home Parenteral Nutrition.

BACKGROUND: Few studies have examined the epidemiology and risk factors for the development of outpatient-acquired catheter-related bloodstream infections (CRBSIs) in children receiving home parenteral nutrition. This study aimed to (1) characterize the incidence, clinical presentation, and epidemiology of CRBSIs and (2) identify risk factors for CRBSIs in children receiving home parenteral nutrition. METHODS: A longitudinal database approved by our Institutional Review Board was created to prospectively track CRBSIs in the UCLA pediatric population from January to December 2012. Eligible patients included those < 18 years old receiving home parenteral nutrition. RESULTS: Thirty of 60 patients (50%) were diagnosed with 66 CRBSIs, for an overall CRBSI rate of 3.6 per 1000 catheter days. Of the CRBSIs, 73% were due to single microorganisms and 27% were polymicrobial. There was a significant difference in median (range) time for blood cultures to turn positive depending on type of CRBSIs (p = 0.03), with polymicrobial infections detected at 13.4 (8.7-24.3) hours, gram-negative infections at 16.5 (9-30.8) hours, and gram-positive infections at 18.9 (8.4-37.1) hours. The most common presenting symptom was fever (82%), followed by gastrointestinal symptoms (42%) and chills (29%). The only significant multivariate risk factor for CRBSIs was presence of a feeding tube (2.3-fold increase in CRBSI risk, p = 0.04). DISCUSSION: Outpatient-acquired CRBSIs are common in children receiving home parenteral nutrition. CRBSIs typically present with fever, but are also associated with gastrointestinal and/or respiratory symptoms. The presence of feeding tubes may predispose children on home parenteral nutrition to developing CRBSIs.