Loss-of-function SLC30A2 mutants are associated with gut dysbiosis and alterations in intestinal gene expression in preterm infants

Loss of Paneth cell (PC) function is implicated in intestinal dysbiosis, mucosal inflammation, and numerous intestinal disorders, including necrotizing enterocolitis (NEC). Studies in mouse models show that zinc transporter ZnT2 (SLC30A2) is critical for PC function, playing a role in granule formation, secretion, and antimicrobial activity; however, no studies have investigated whether loss of ZnT2 function is associated with dysbiosis, mucosal inflammation, or intestinal dysfunction in humans. SLC30A2 was sequenced in healthy preterm infants (26-37 wks; n = 75), and structural analysis and functional assays determined the impact of mutations. In human stool samples, 16S rRNA sequencing and RNAseq of bacterial and human transcripts were performed. Three ZnT2 variants were common (>5%) in this population: H346Q, f = 19%; L293R, f = 7%; and a previously identified compound substitution in Exon7, f = 16%). H346Q had no effect on ZnT2 function or beta-diversity. Exon7 impaired zinc transport and was associated with a fractured gut microbiome. Analysis of microbial pathways suggested diverse effects on nutrient metabolism, glycan biosynthesis and metabolism, and drug resistance, which were associated with increased expression of host genes involved in tissue remodeling. L293R caused profound ZnT2 dysfunction and was associated with overt gut dysbiosis. Microbial pathway analysis suggested effects on nucleotide, amino acid and vitamin metabolism, which were associated with the increased expression of host genes involved in inflammation and immune response. In addition, L293R was associated with reduced weight gain in the early postnatal period. This implicates ZnT2 as a novel modulator of mucosal homeostasis in humans and suggests that genetic variants in ZnT2 may affect the risk of mucosal inflammation and intestinal disease.

Image-based assessment of sarcopenic obesity predicts mortality in major trauma

BACKGROUND

Patients with obesity are also at risk for sarcopenia, which is difficult to recognize in this population. Our study examines whether sarcopenic-obesity (SO) is independently associated with mortality in trauma.

METHODS

Using a retrospective database, we performed logistic regression analysis. . Admission CT scans were used to identify SO by calculating the visceral fat to skeletal muscle ratio >3.2.

RESULTS

Of 883 patients, the prevalence of SO was 38% (333). Patients with SO were more likely to be male (79% versus 43%, p < 0.001), older (mean 66.5 years versus 46.3 years, p < 0.001), and less likely to have an injury severity score (ISS) ≥ 24 (43% versus 55%, p = 0.0003). Using multivariable logistic regression analysis, SO was independently associated with mortality (OR 2.8; 95% CI 1.6-4.8, p < 0.001). Causal mediation analysis found admission hyperglycemia as a mediator for mortality.

CONCLUSIONS

Sarcopenic obesity is an independent predictor of mortality in major trauma.

Nudging patients and surgeons to change ambulatory surgery pain management: Results from an opioid buyback program

BACKGROUND

Optimal postoperative opioid stewardship combines adequate pain medication to control expected discomfort while avoiding abuse and community diversion of unused prescribed opioids. We hypothesized that an opioid buyback program would motivate patients to return unused opioids, and surgeons will use that data to calibrate prescribing.

METHODS

Prospective cohort study of postambulatory surgery pain management at a level II Veterans Affairs rural hospital (2017-2019). Eligible patients were offered $5/unused opioid pill ($50 limit) returned to our Veterans Affairs hospital for proper disposal. After 6 months, buyback data was shared with each surgical specialty.

RESULTS

Overall, 934 of 1,880 (49.7%) eligible ambulatory surgery patients were prescribed opioids and invited to participate in the opioid buyback. We had 281 patients (30%) return 3,165 unused opioid pills; this return rate remained constant over the study period. In 2017, 62.4% of patients were prescribed an opioid; after data was shared with providers, prescriptions for opioids were reduced to 50.7% and 38.3% of eligible patients in 2018 and 2019, respectively (P < .0001). The median morphine milligram equivalents prescribed also decreased from 108.8 morphine milligram equivalents in 2017 to 75.0 morphine milligram equivalents in 2018 and sustained at 75.0 morphine milligram equivalents in 2019 (P < .001). Surgical providers, surgeries performed, patient characteristics, and 30-day refill rates were similar throughout the study period.

CONCLUSION

A small financial incentive resulted in patients returning unused opioids after ambulatory surgery. Feedback to surgeons regarding opioids returned reduced the proportion of patients prescribed an opioid and the amount of opioid after ambulatory surgery without an increase in refills.

Incidence, risk factors, and outcomes of early postoperative hyperglycemia in surgical patients: a protocol for a systematic review and meta-analysis

BACKGROUND

Early postoperative hyperglycemia (POHG) is common and associated with poor postoperative outcomes. Currently, there is no systematic review and meta-analysis that addresses the knowledge gap of the incidence of POHG in surgical patients and that explores the associated risk factors and complications. The objective of this study will be to estimate the pooled incidence, risk factors, and clinical outcomes of early postoperative hyperglycemia in men and women globally.

METHODS

We designed and registered a study protocol for a systematic review and meta-analysis of studies reporting the incidence of postoperative hyperglycemia (POHG). We will search PubMed (MEDLINE), Scopus, Web of Science, EMBASE, Cochrane Library, OVID (HEALTH STAR), OVID (MEDLINE), and Joana Briggs Institute EBF Database (from inception onwards). Randomized controlled trials and observational cohort studies reporting the incidence of POHG and conducted in surgical patients will be included. No age, geographical location, study design, or language limits will be applied. The primary outcome will be the incidence of POHG. Secondary outcomes will be risk factors and clinical outcomes of POHG. Two reviewers will independently screen citations, full text articles, and abstract data, extract data, and evaluate the quality and bias of included studies. Discrepancies will be resolved through discussion or consultation with a third researcher. The risk of bias and study methodological quality of included studies will be evaluated by the appropriate Cochrane risk of bias tool for randomized trials and Newcastle-Ottawa Scale for cohort studies. If feasible, we will conduct random effects meta-analysis with a logit transformation of proportions. We will report the probability of postoperative hyperglycemia as a measure of incidence rate, relative risk ratios (RR), and 95% confidence intervals to report the effects of the risk factors and postoperative outcomes. Additional analyses will be conducted to explore the potential sources of heterogeneity (e.g., age, gender, geographical location, publication year, comorbidities, type of surgical procedure). The Egger test and funnel plots will be used to assess small study effects (publication bias).

DISCUSSION

This systematic review and meta-analysis will identify, evaluate, and integrate the evidence on the incidence, risk factors, and outcomes of early POHG in surgical patients. The results of this study can be used to identify populations which may be at particular risk for POHG. Future studies which use this information to better guide post-operative glycemic control in surgical patients could be considered.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42020167138.

Macrolets: Outsized Extracellular Vesicles Released from Lipopolysaccharide-Stimulated Macrophages that Trap and Kill Escherichia coli

Macrophages release a variety of extracellular vesicles (EVs). Here we describe a previously unreported class of EVs that are released from macrophages in response to Escherichia coli endotoxin, lipopolysaccharide (LPS), that we have named "macrolets" since they are extruded as large "droplets" released from macrophages. Morphologically, macrolets are anuclear, bounded by a single lipid membrane and structurally dependent on an actin cytoskeleton. Macrolets are enriched in tetraspanins and separable on this basis from their parent macrophages. Macrolets are distinguished from classic exosomes by their larger size (10–30 μm), discoid shape, and the presence of organelles. Macrolets are rich in both interleukin 6 (IL-6) and interleukin 6 receptor (IL-6R),and are capable of trapping and killing E. coli in association with production of reactive oxygen species. Our observations offer insights into the mechanisms by which macrophage activities may be amplified in sites of infection, inflammation, and healing.

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Macrolets, outsized extracellular vesicles, release from LPS-stimulated macrophages

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Macrolets are rich in tetraspanin proteins such as CD81, CD63, and CD9

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Macrolets capture and internalize E. coli bacteria within acidic compartments

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Macrolets kill E. coli by a mechanism associated with production of ROS and superoxide

The Impact of Minimally Invasive Gastrectomy on Survival in the USA

BACKGROUND

Minimally invasive surgical approaches for gastric adenocarcinoma are increasing in prevalence. Although recent studies suggest such approaches are associated with improvements in short-term outcomes, long-term outcomes have not been well studied. This study aimed to evaluate the impact of minimally invasive gastrectomy on long-term survival.

METHODS

The National Cancer Database (NCDB) was used to identify patients who underwent gastrectomy for adenocarcinoma between 2010 and 2015. Patient characteristics were stratified by open and minimally invasive approaches and compared using chi-square and t tests. Unadjusted survival functions were estimated using Kaplan-Meier methodology. Multivariable modeling of risks factors for survival was analyzed with Cox proportional hazard models. Covariate imbalance was controlled using propensity score matching.

RESULTS

The study included 17,449 patients who underwent gastrectomy. Cox proportional hazard modeling demonstrated that minimally invasive surgery improved survival (hazard ratio = 0.86, P < 0.0001). Predictors of worsened survival included community facility type, comorbidities, tumor size, extent of gastrectomy, clinical T and N staging (P < 0.0060 for all). After propensity score matching, minimally invasive surgery had a significantly improved survival at 5 years compared to an open approach, 51.9% versus 47.7% (P < 0.0001). Survival was not significantly different between propensity score-matched patients who received laparoscopic and robotic approaches (P = 0.2611).

CONCLUSIONS

Minimally invasive approaches for gastric carcinoma are associated with improved long-term survival. There was no significant difference in survival when comparing laparoscopic to robotic gastrectomy. The mechanisms that drive these improvements deserve further investigation.

A common genetic variant in zinc transporter ZnT2 (Thr288Ser) is present in women with low milk volume and alters lysosome function and cell energetics

Suboptimal lactation is a common, yet underappreciated cause for early cessation of breastfeeding. Molecular regulation of mammary gland function is critical to the process lactation; however, physiological factors underlying insufficient milk production are poorly understood. The zinc (Zn) transporter ZnT2 is critical for regulation of mammary gland development and maturation during puberty, lactation, and postlactation gland remodeling. Numerous genetic variants in the gene encoding ZnT2 (SLC30A2) are associated with low milk Zn concentration and result in severe Zn deficiency in exclusively breastfed infants. However, the functional impacts of genetic variation in ZnT2 on key mammary epithelial cell functions have not yet been systematically explored at the cellular level. Here we determined a common mutation in SLC30A2/ZnT2 substituting serine for threonine at amino acid 288 (Thr288Ser) was found in 20% of women producing low milk volume (n = 2/10) but was not identified in women producing normal volume. Exploration of cellular consequences in vitro using phosphomimetics showed the serine substitution promoted preferential phosphorylation of ZnT2, driving localization to the lysosome and increasing lysosome biogenesis and acidification. While the substitution did not initiate lysosome-mediated cell death, cellular ATP levels were significantly reduced. Our findings demonstrate the Thr288Ser mutation in SLC30A2/ZnT2 impairs critical functions of mammary epithelial cells and suggest a role for genetic variation in the regulation of milk production and lactation performance.

Risk factors of perioperative mortality from complicated peptic ulcer disease in Africa: systematic review and meta-analysis

Introduction

In 2013, peptic ulcer disease (PUD) caused over 300 000 deaths globally. Low-income and middle-income countries are disproportionately affected. However, there is limited information regarding risk factors of perioperative mortality rates in these countries.

Objective

To assess perioperative mortality rates from complicated PUD in Africa and associated risk factors.

Design

We performed a systematic review and a random-effect meta-analysis of literature describing surgical management of complicated PUD in Africa. We used subgroup analysis and meta-regression analyses to investigate sources of variations in the mortality rates and to assess the risk factors contributing to mortality.

Results

From 95 published reports, 10 037 patients underwent surgery for complicated PUD. The majority of the ulcers (78%) were duodenal, followed by gastric (14%). Forty-one per cent of operations were for perforation, 22% for obstruction and 9% for bleeding. The operations consisted of vagotomy (38%), primary repair (34%), resection and reconstruction (12%), and drainage procedures (6%). The overall PUD mortality rate was 6.6% (95% CI 5.4% to 8.1%). It increased to 9.7% (95% CI 7.1 to 13.0) when we limited the analysis to studies published after the year 2000. The correlation was higher between perforated PUD and mortality rates (r=0.41, p<0.0001) than for bleeding PUD and mortality rates (r=0.32, p=0.001). Non-significant differences in mortality rates existed between sub-Saharan Africa (SSA) and North Africa and within SSA.

Conclusion

Perioperative mortality rates from complicated PUD in Africa are substantially high and could be increasing over time, and there are possible regional differences.

Regional, racial, gender, and tumor biology disparities in breast cancer survival rates in Africa: A systematic review and meta-analysis

BACKGROUND

The survival rates from breast cancer in Africa are poor and yet the incidence rates are on the rise. In this study, we hypothesized that, in Africa, a continent with great disparities in socio-economic status, race, tumor biology, and cultural characteristics, the survival rates from breast cancer vary greatly based on region, tumor biology (hormone receptor), gender, and race. We aimed to conduct the first comprehensive systematic review and meta-analysis on region, gender, tumor-biology and race-specific 5-year breast cancer survival rates in Africa and compared them to 20-year survival trends in the United States.

METHODS

We searched MEDLINE, EMBASE, and Cochrane Library to identify studies on breast cancer survival in African published before October 17, 2018. Pooled 5-year survival rates of breast cancer were estimated by random-effects models. We explored sources of heterogeneity through subgroup meta-analyses and meta-regression. Results were reported as absolute difference (AD) in percentages. We compared the survival rates of breast cancer in Africa and the United States.

FINDINGS

There were 54 studies included, consisting of 18,970 breast cancer cases. There was substantial heterogeneity in the survival rates (mean 52.9%, range 7-91%, I2 = 99.1%; p for heterogeneity <0.0001). Meta-regression analyses suggested that age and gender-adjusted 5-year survival rates were lower in sub-Saharan Africa compared to north Africa (AD: -25.4%; 95% CI: -34.9 - -15.82%), and in predominantly black populations compared to predominantly non-black populations (AD: -25.9%; 95% CI: 35.40 - -16.43%). Survival rates were 10 percentage points higher in the female population compared to male, but the difference was not significant. Progesterone and estrogen receptor-positive breast cancer subtypes were positively associated with survival (r = 0.39, p = 0.08 and r = 0.24, p = 0.29 respectively), but triple-negative breast cancer was negatively associated with survival. Survival rates are increasing over time more in non-black Africans (55% in 2000 versus 65% in 2018) compared to black Africans (33% in 2000 versus 40% in 2018); but, the survival rates for Africans are still significantly lower when compared to black (76% in 2015) and white (90% in 2015) populations in the United States.

CONCLUSION

Regional, sub-regional, gender, and racial disparities exist, influencing the survival rates of breast cancer in Africa. Therefore, region and race-specific public health interventions coupled with prospective genetic studies are urgently needed to improve breast cancer survival in this region.

Pain and Dysfunction with Sexual Activity after Inguinal Hernia Repair: Systematic Review and Meta-Analysis

BACKGROUND

The reported incidence rates of sexual dysfunction (SD) and pain with sexual activity (PSA) after inguinal hernia repair in males vary considerably. This meta-analysis explores the rates of SD and PSA after different surgical and anesthesia types to understand patient risk after inguinal hernia repair.

STUDY DESIGN

We performed a systematic review and meta-analysis using Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines to search 3 databases (EMBASE, MEDLINE, and Cochrane Library). We identified retrospective, prospective, and randomized controlled trial studies, published on or before March 1, 2019, reporting on SD and PSA after inguinal hernia repair. We used random-effects models to calculate pooled estimates of incidence rates of SD and PSA after inguinal hernia repair. Subgroup meta-analyses and meta-regression were used to explore sources of variation.

RESULTS

A total of 4,884 patients from 12 studies were identified. Study-level median age at the time of repair was 52.3 years old, and study-level median follow-up was 10.5 months. Definitions of SD and PSA focused on completion of intercourse for the former and pain with erection/ejaculation for the latter. The overall incidence of new-onset, postoperative SD was 5.3% (95% CI 3.6% to 7.9%) and of PSA was 9.0% (95% CI 5.8% to 13.6%). Rates of SD associated with minimally invasive surgical (MIS) and open repair were, respectively, 7.8% (95% CI 5.4% to 11.3%) and 3.7% (95% CI 2.0% to 6.8%); rates of PSA were 7.4% (95% CI 4.7% to 11.5%) and 12.5% (95% CI 6.4% to 23.3%), respectively.

CONCLUSIONS

Sexual dysfunction and PSA are not rare after inguinal hernia repair. They should be included in preoperative discussions and as standard metrics in reporting outcomes of repair in large cohorts or trials.

The Role of Genetic Variant rs13266634 in SLC30A8/ZnT8 in Post-Operative Hyperglycemia after Major Abdominal Surgery

CONTEXT

Following major surgery, post-operative hyperglycemia (POHG) is associated with suboptimal outcomes, among diabetics and non-diabetics. A specific genetic variant, rs13266634 (c.973C>T; p.ARG325TRP) in zinc transporter SLC30A8/ZnT8, is associated with protection against Type-2 Diabetes, suggesting it may be actionable for predicting and preventing POHG.

OBJECTIVE

To determine independent and mediated influences of a genetic variant on POHG in patients undergoing a model major operation, complex abdominal ventral hernia repair (cVHR).

PATIENTS AND METHODS

For 110 patients (mean BMI 34.9±5.8, T2D history 28%) undergoing cVHR at a tertiary referral center (January 2012 to March 2017), multivariate regression was used to correlate the rs13266634 variant to pre-operative clinical, laboratory and imaging-based indices of liver steatosis and central abdominal adiposity to POHG. Causal Mediation Analysis (CMA) was used to determine direct and mediated contributions of SLC30A8/ZnT8 status to POHG.

RESULTS

Variant rs13266634 was present in 61 patients (55.4%). In univariate models, when compared to patients with rs13266634, the homozygous wild-genotype (C/C, n=49) was associated with significantly higher risks of POHG (OR= 0.30 95%CI =0.14, 0.67, P=0.0038). Multivariate regression indicated that the association was independent (OR= 0.39 95%CI 0.15-0.97, p=0.040). In addition, CMA suggested that rs13266634 protects against POHG directly and indirectly through its influence on liver steatosis and central adiposity.

CONCLUSIONS

In medically complex patients undergoing major operations, the rs13266634 variant protects against POHG and its associated outcomes, through independent and mediated contributions. In C/C patients undergoing major operations, SLC30A8/ZnT8 may prove useful to stratify risk of POHG and potentially as a therapeutic target.

Excess Dietary Zinc Intake in Neonatal Mice Causes Oxidative Stress and Alters Intestinal Host-Microbe Interactions

SCOPE

Greater than 68% of young infants are exposed to dietary zinc (Zn) levels that are higher than the Tolerable Upper Intake Limit. However, the consequences of excess dietary Zn during early life on intestinal function and host-microbe interactions are unknown.

METHODS AND RESULTS

Neonatal mice are gavaged with 100 Zn µg d^-1 from postnatal day (PN) 2 through PN10 and indices of intestinal function and host-microbe interactions are compared to unsupplemented mice. Excess dietary Zn causes oxidative stress, increases goblet cell number and mucus production, and are associated with increased intestinal permeability and systemic inflammation. Over 900 genes are differentially expressed; 413 genes display a fold-change >1.60. The Gene Ontology Biological processes most significantly affected include biological adhesion, the immune system, metabolic processes, and response to stimulus. Key genes most highly and significantly upregulated include ALDH2, MT1, TMEM6, CDK20, and COX62b, while CALU, ST3GAL4, CRTC2, SLC28A2, and COMMA1 are downregulated. These changes are associated with a microbiome enriched in pathogenic taxa including Pseudomonadales and Campylobacter, and greater expression of bacterial stress response genes.

CONCLUSION

Excess dietary Zn may have unforeseen influences on epithelial signaling pathways, barrier function, and luminal ecology in the intestine that may have long-term consequences on intestinal health.

Marginal dietary zinc deprivation augments sepsis-induced alterations in skeletal muscle TNF-α but not protein synthesis

Severe zinc deficiency is associated with an increased systemic inflammatory response and mortality after sepsis. However, the impact of mild zinc deficiency, which is more common in populations with chronic illnesses and sepsis, is unknown. In this study, we hypothesized that marginal dietary Zn deprivation (ZM) would amplify tissue inflammation and exacerbate the sepsis-induced decrease in muscle protein synthesis. Adult male C57BL/6 mice were fed a zinc-adequate (ZA) or ZM diet (30 or 10 mg Zn/kg, respectively) over 4 weeks, peritonitis was induced by cecal ligation and puncture (CLP), and mice were examined at either 24 h (acute) or 5 days (chronic) post-CLP Acute sepsis decreased the in vivo rate of skeletal muscle protein synthesis and the phosphorylation of the mTOR substrate 4E-BP1. Acutely, sepsis increased TNF-α and IL-6 mRNA in muscle, and the increase in TNF-α was significantly greater in ZM mice. However, muscle protein synthesis and 4E-BP1 phosphorylation returned to baseline 5 days post-CLP in both ZA and ZM mice. Protein degradation via markers of the ubiquitin proteasome pathway was increased in acute sepsis, yet only MuRF1 mRNA was increased in chronic sepsis and ZM amplified this elevation. Our data suggest that mild zinc deficiency increases TNF-α in muscle acutely after sepsis but does not significantly modulate the rate of muscle protein synthesis.

Inability to replete white adipose tissue during recovery phase of sepsis is associated with increased autophagy, apoptosis, and proteasome activity

Adipose tissue is an important energy depot and endocrine organ, and the degree of adiposity impacts the host response to infection. However, little is known regarding the mechanisms by which white adipose tissue (WAT) is lost acutely and then restored after the resolution of sepsis. Therefore, the signaling pathways governing protein synthesis, autophagy, apoptosis, and the ubiquitin-proteasome were investigated to identify potential mechanisms mediating the acute (24 h) loss of WAT after cecal ligation and puncture as well as the failure to replenish WAT during recovery (day 10). While whole body fat mass was decreased equally in pair-fed control and septic mice at 5 days after cecal ligation and puncture, fat mass remained 35% lower in septic mice at day 10 During sepsis-recovery, protein synthesis in epididymal WAT was increased compared with control values, and this increase was associated with an elevation in eukaryotic translation initiation factor (eIF)2Bε but no change in mammalian target of rapamycin complex 1 activity (eIF4E-binding protein-1 or S6 kinase 1 phosphorylation). Protein breakdown was increased during sepsis-recovery, as evidenced by the elevation in ubiquitin-proteasome activity. Moreover, indexes of autophagy (light chain 3B-II, autophagy-related protein 5/12, and beclin) were increased during sepsis-recovery and associated with increased AMP-activated kinase-dependent Ser⁵⁵⁵-phosphorylated Unc-51-like autophagy activating kinase-1. Apoptosis was increased, as suggested by the increased cleavage of caspase-3 and poly(ADP-ribose) polymerase. These changes were associated with increased inflammasome activity (increased NLR family, pyrin domain containing 3; TMS1; and caspase-1 cleavage) and the endoplasmic reticulum stress response (increased eIF2α and activating transcription factor-4) and browning (uncoupling protein-1) in epididymal WAT. Our data suggest that WAT stores remain depleted during recovery from sepsis due to sustained inflammation and elevations in protein and cellular degradation, despite the increase in protein synthesis.

Immune and metabolic responses in early and late sepsis during mild dietary zinc restriction

BACKGROUND

Mild dietary zinc (Zn) deficiency is widespread in human populations, but its influence on recovery after acute illness is poorly understood. In a mouse model of abdominal sepsis (cecal ligation puncture), systemic immune responses and liver metabolism were monitored in early (24 h) and late (5 d) phases, under control conditions and during mild dietary Zn restriction.

METHODS

Mice were fed diets adequate or marginally deficient (ZM) in Zn (30 versus 10 mg zinc/kg diet) for 4 wk, before undergoing laparotomy alone (nonseptic control) or cecal ligation puncture (septic).

RESULTS

Among nonseptic mice, the ZM state was not associated with differences in inflammation or metabolic responses. Among septic mice, mortality did not differ between the zinc adequate and ZM groups. In the early phase, the ZM state amplified increases in plasma interleukin (IL) 6, tumor necrosis factor alpha, and IL-10, while dampening the interferon gamma response. In the late phase, subtle but significant ZM-associated increases were observed in plasma IL-5 and interferon gamma levels and hepatic protein synthesis, the latter of which appeared to be mammalian target of rapamycin independent and was associated with increased hepatic tumor necrosis factor alpha messenger RNA content.

CONCLUSIONS

Without increasing mortality, the ZM state is associated with a more disordered acute systemic inflammatory response and persistence or enhancement of acute phase responses within the liver parenchyma.

Oral omega-3 fatty acids promote resolution in chemical peritonitis

BACKGROUND

Recent studies suggest that purified omega-3 fatty acids may attenuate acute inflammation and hasten the transition to healing. In this study, we tested the hypothesis that pretreatment with omega-3-rich fish oil (FO) would promote resolution of peritoneal inflammation through production of specific lipid mediators.

METHODS

C57/BL6 mice were given a daily 200-μL oral gavage of saline (CTL) or FO (1.0-1.5 g/kg/d docosahexaenoic acid and 1.3-2.0 g/kg/d eicosapentaenoic acid) for 7 d before chemical peritonitis was induced with thioglycollate. Peritoneal lavage fluid was collected before induction and at days 2 and 4 after peritonitis onset. Prostaglandin E2 (PGE2), Leukotriene B4 (LTB4), Resolvin D1 (RvD1), and the composition of immune cell populations were examined in peritoneal lavage exudates. Cells harvested from the peritoneum were assessed for macrophage differentiation markers, phagocytosis, and lipopolysaccharide-induced cytokine secretion profiles (interleukin [IL]-6, IL-10, IL-1β, TNFα).

RESULTS

The ratio of RvD1 to pro-inflammatory PGE2 and LTB4 was increased in the peritoneal cavity of FO-supplemented animals. FO induced a decrease in the number of monocytes in the lavage fluid, with no change in the number of macrophages, neutrophils, or lymphocytes. Macrophage phagocytosis and M1/M2 messenger RNA markers were unchanged by FO with the exception of decreased PPARγ expression. FO increased ex vivo TNFα secretion after stimulation with lipopolysaccharide.

CONCLUSIONS

Our findings provide evidence that nutraceutically relevant doses of FO supplements given before and during chemical peritonitis shift the balance of lipid mediators towards a proresolution, anti-inflammatory state without drastically altering the number or phenotype of local innate immune cell populations.

ZnT2-Mediated Zinc Import Into Paneth Cell Granules Is Necessary for Coordinated Secretion and Paneth Cell Function in Mice

BACKGROUND & AIMS

Defects in Paneth cell (PC) function are associated with microbial dysbiosis and intestinal inflammation. PC granules contain antimicrobial peptides, cytokines, and substantial stores of zinc (Zn). We hypothesized that Zn, transported into the granule through the Zn transporter (ZnT)2, is critical for signature PC functions.

METHODS

ZnT2 was localized to PC granules using immunofluorescence and sucrose gradient fractionation in wild-type (wt) mice, and consequences of ZnT2 loss were characterized in ZnT2 knockout (ZnT2ko) mice. Terminal ilea were harvested for immunofluorescence, electron microscopy, and fluorescent imaging with the Zn reporter Zinpyr-1. Alterations in fecal microbiota were characterized using 16s ribosomal RNA sequencing. PC degranulation, bacterial translocation, cytokine response to Escherichia coli endotoxin lipopolysaccharide, crypt viability after exposure to the oxidant monochloramine (NH₂Cl), and bactericidal activity of luminal contents of terminal ilea against enteropathogenic E coli were assessed.

RESULTS

ZnT2 was localized to the membrane of PC granules. In ZnT2ko mice, spontaneous degranulation was observed more frequently than among wt mice. Secretory granules were hypodense with less active lysozyme, and there was evidence of autophagosome accumulation and granule degradation in PCs from ZnT2ko mice. Gut microbiota of ZnT2ko mice were enriched in Bacteroidales S24-7 and relatively depleted of species commonly found in wt mice. Evidence of PC dysfunction in ZnT2ko mice included impaired granule secretion and increased inflammatory response to lipopolysaccharide, less bactericidal activity, and greater susceptibility to cell death from NH₂Cl.

CONCLUSIONS

ZnT2 is critical for Zn import into PC granules, and the inability to import Zn leads to profound defects in PC function and uncoordinated granule secretion.

Subtype-specific accumulation of intracellular zinc pools is associated with the malignant phenotype in breast cancer

BACKGROUND

Zinc (Zn) hyper-accumulates in breast tumors and malignant cell lines compared to normal mammary epithelium. The mechanisms responsible for Zn accumulation and the consequence of Zn dysregulation are poorly understood.

METHODS

Microarrays were performed to assess differences in the expression of Zn transporters and metallothioneins (MTs) in human breast tumors and breast cancer cell lines. Real-time PCR and immunoblotting were employed to profile Zn transporter expression in representative luminal (T47D), basal (MDA-MB-231), and non-malignant (MCF10A) cell lines. Zn distribution in human tumors was assessed by X-ray fluorescence imaging. Zn distribution and content in cell lines was measured using FluoZin-3 imaging, and quantification and atomic absorption spectroscopy. Functional consequences of ZnT2 over-expression in MDA-MB-231 cells including invasion, proliferation, and cell cycle were measured using Boyden chambers, MTT assays, and flow cytometry, respectively.

RESULTS

Gene expression profiling of human breast tumors and breast cancer cell lines identified subtype-specific dysregulation in the Zn transporting network. X-ray fluorescence imaging of breast tumor tissues revealed Zn hyper-accumulation at the margins of Luminal breast tumors while Zn was more evenly distributed within Basal tumors. While both T47D and MDA-MB-231 cells hyper-accumulated Zn relative to MCF10A cells, T47D cells accumulated 2.5-fold more Zn compared to MDA-MB-231 cells. FluoZin-3 imaging indicated that Zn was sequestered into numerous large vesicles in T47D cells, but was retained in the cytoplasm and found in fewer and larger, amorphous sub-cellular compartments in MDA-MB-231 cells. The differences in Zn localization mirrored the relative abundance of the Zn transporter ZnT2; T47D cells over-expressed ZnT2, whereas MDA-MB-231 cells did not express ZnT2 protein due to proteasomal degradation. To determine the functional relevance of the lack of ZnT2 in MDA-MB-231cells, cells were transfected to express ZnT2. ZnT2 over-expression led to Zn vesicularization, shifts in cell cycle, enhanced apoptosis, and reduced proliferation and invasion.

CONCLUSIONS

This comprehensive analysis of the Zn transporting network in malignant breast tumors and cell lines illustrates that distinct subtype-specific dysregulation of Zn management may underlie phenotypic characteristics of breast cancers such as grade, invasiveness, metastatic potential, and response to therapy.

Marginal zinc intake reduces the protective effect of lactation on mammary gland carcinogenesis in a DMBA-induced tumor model in mice

Breastfeeding can reduce breast cancer risk; however, unknown factors modify this protective effect. Zinc (Zn) modulates an array of cellular functions including oxidative stress, cell proliferation, motility and apoptosis. Marginal Zn intake is common in women and is associated with breast cancer. We reported that marginal Zn intake in mice leads to mammary gland hypoplasia and hallmarks of pre-neoplastic lesions. In the present study, we tested the hypothesis that marginal Zn intake confounds the protective effect of lactation on breast cancer. Nulliparous mice fed control (ZA, 30 mg Zn/kg) or a marginal Zn diet (ZD, 15 mg Zn/kg), were bred and offspring were weaned naturally. Post-involution, mice were gavaged with corn oil or 7,12-dimethylbenz(a)anthracene (DMBA, 1 mg/wk for 4 weeks) and tumor development was monitored. A ZD diet led to insufficient involution, increased fibrosis and oxidative stress. Following DMBA treatment, mice fed ZD had higher oxidative stress in mammary tissue that correlated with reduced levels of peroxiredoxin-1 and p53 and tended to have shorter tumor latency and greater incidence of non-palpable tumors. In summary, marginal Zn intake creates a toxic mammary gland microenvironment and abrogates the protective effect of lactation on carcinogenesis.

Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction

The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36% of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D(103)E and T(288)S) were identified with high frequency (9 and 16%, respectively) and expression of T(288)S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A(28)D, K(66)N, Q(71)H, D(103)E, A(105)P, Q(137)H, T(288)S and T(312)K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either 'loss-of-function' or 'gain-of-function', and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.

Emphysematous gastritis and gastric emphysema: similar radiographic findings, distinct clinical entities

INTRODUCTION

Despite similar appearances on imaging studies, emphysematous gastritis (EG) and gastric emphysema (GE) are rare clinical entities encountered in surgical practices. The purpose of this review is to clarify the presentation, natural history, and optimal treatment strategies for these two disorders.

METHODS

We conducted a comprehensive literature review for reported adult cases of EG and GE in MEDLINE. Two cases from our institution were also included. Patient with demographics, diagnostic and therapeutic data, and outcomes were compared between patients with EG and GE.

RESULTS

A total of 75 cases were included for our review. The finding of intramural air in the stomach was often associated with portal vein gas, pneumatosis intestinalis, or pneumoperitoneum in both groups. Surgical removal of the stomach was performed in 23.1% of EG patients, but only one patient in the GE group. In the EG group, overall mortality (55%) appeared to be driven by sepsis and its complications, whereas in the GE group, mortality (29%) was attributable to comorbid conditions and the underlying illness.

CONCLUSIONS

Prompt surgical intervention is more commonly indicated for severe EG and is directed at removal of the septic organ, while the primary indication for surgical intervention in GE is the uncertainty of the diagnosis.

Redistribution of tissue zinc pools during lactation and dyshomeostasis during marginal zinc deficiency in mice

Zinc (Zn) requirements are increased during lactation. Increased demand is partially met through increased Zn absorption from the diet. It is estimated that 60-80% of women of reproductive age are at risk for Zn deficiency due to low intake of bioavailable Zn and increased demands during pregnancy and lactation. How Zn is redistributed within the body to meet the demands of lactation, and how Zn deficiency affects this process, is not understood. Female C57bl/6J mice were fed a control (ZA; 30mg Zn/kg) or a marginally Zn deficient (ZD; 15mg Zn/kg) diet for 30 days prior to mating through mid-lactation and compared with nulliparous mice fed the same diets. While stomach and plasma Zn concentration increased during lactation in mice fed ZA, mice fed ZD had lower stomach Zn concentration and abrogated plasma Zn levels during lactation. Additionally, femur Zn decreased during lactation in mice fed ZA, while mice fed ZD did not experience this decrease. Furthermore, red blood cell, pancreas, muscle and mammary gland Zn concentration increased, and liver and adrenal gland Zn decreased during lactation, independent of diet, while kidney Zn concentration increased only in mice fed ZD. Finally, maternal Zn deficiency significantly increased the liver Zn concentration in offspring but decreased weight gain and survival. This study provides novel insight into how Zn is redistributed to meet the increased metabolic demands of lactation and how marginal Zn deficiency interferes with these homeostatic adjustments.

Paradoxical zinc toxicity and oxidative stress in the mammary gland during marginal dietary zinc deficiency

Zinc (Zn) regulates numerous cellular functions. Zn deficiency is common in females; ∼80% of women and 40% of adolescent girls consume inadequate Zn. Zn deficiency enhances oxidative stress, inflammation and DNA damage. Oxidative stress and inflammation is associated with breast disease. We hypothesized that Zn deficiency increases oxidative stress in the mammary gland, altering the microenvironment and architecture. Zn accumulated in the mammary glands of Zn deficient mice and this was associated with macrophage infiltration, enhanced oxidative stress and over-expression of estrogen receptor α. Ductal and stromal hypercellularity was associated with aberrant collagen deposition and disorganized e-cadherin. Importantly, these microenvironmental alterations were associated with substantial impairments in ductal expansion and mammary gland development. This is the first study to show that marginal Zn deficiency creates a toxic microenvironment in the mammary gland impairing breast development. These changes are consistent with hallmarks of potential increased risk for breast disease and cancer.

Operative volume in colon surgery: a matched cohort analysis

Although previous studies have suggested that higher volumes of colectomies performed by surgeons and hospitals are associated with lower mortality, less is known about the relationship between volume and resource utilization. The research team tested the association between volume, costs, complications, length of stay, and mortality using data from the National Inpatient Sample. Results suggest higher volumes for both surgeons and hospitals were associated with lower costs, fewer complications, shorter length of stay, and lower mortality. Propensity score matching showed no significant difference in mortality by surgeon volume (7.38% vs 7.46%, P=.0.842), but significantly fewer complications (45.06% vs 49.10%, P=.008), shorter length of stay (11.8 vs 13.1 days, P<.0001), and lower costs ($33,142 vs $29,578, P<.0001) for high-volume surgeons. Although the major driver of complications and mortality is burden of disease and comorbid conditions, individual surgeon volume is an important determinant of length of stay and costs.

Operative management of recurrent choledocholithiasis

INTRODUCTION

With the advent of endoscopic and image-directed percutaneous approaches, it is increasingly uncommon to require a surgical approach for recurrent bile duct stones.

TECHNIQUE

We describe open side-to-side choledochoduodenostomy as one of the surgical options for recurrent bile duct stones. This procedure includes the following elements: exposure of the common bile duct, mobilization of the duodenum (Kocher maneuver), choledochotomy, inspection of the bile duct with a choledochoscopy, and anastomosis of the bile duct with the duodenum. Other options for operative management are discussed.

CONCLUSION

Surgical drainage procedures for recurrent bile duct stones can be performed for patients who fail to respond to endoscopic and nonoperative interventional treatments with good long-term outcomes.

Demand for Zn2+ in acid-secreting gastric mucosa and its requirement for intracellular Ca2+

BACKGROUND AND AIMS

Recent work has suggested that Zn(2+) plays a critical role in regulating acidity within the secretory compartments of isolated gastric glands. Here, we investigate the content, distribution and demand for Zn(2+) in gastric mucosa under baseline conditions and its regulation during secretory stimulation.

METHODS AND FINDINGS

Content and distribution of zinc were evaluated in sections of whole gastric mucosa using X-ray fluorescence microscopy. Significant stores of Zn(2+) were identified in neural elements of the muscularis, glandular areas enriched in parietal cells, and apical regions of the surface epithelium. In in vivo studies, extraction of the low abundance isotope, (70)Zn(2+), from the circulation was demonstrated in samples of mucosal tissue 24 hours or 72 hours after infusion (250 µg/kg). In in vitro studies, uptake of (70)Zn(2+) from media was demonstrated in isolated rabbit gastric glands following exposure to concentrations as low as 10 nM. In additional studies, demand of individual gastric parietal cells for Zn(2+) was monitored using the fluorescent zinc reporter, fluozin-3, by measuring increases in free intracellular concentrations of Zn(2+) {[Zn(2+)](i)} during exposure to standard extracellular concentrations of Zn(2+) (10 µM) for standard intervals of time. Under resting conditions, demand for extracellular Zn(2+) increased with exposure to secretagogues (forskolin, carbachol/histamine) and under conditions associated with increased intracellular Ca(2+) {[Ca(2+)](i)}. Uptake of Zn(2+) was abolished following removal of extracellular Ca(2+) or depletion of intracellular Ca(2+) stores, suggesting that demand for extracellular Zn(2+) increases and depends on influx of extracellular Ca(2+).

CONCLUSIONS

This study is the first to characterize the content and distribution of Zn(2+) in an organ of the gastrointestinal tract. Our findings offer the novel interpretation, that Ca(2+) integrates basolateral demand for Zn(2+) with stimulation of secretion of HCl into the lumen of the gastric gland. Similar connections may be detectable in other secretory cells and tissues.

Redistribution of labile plasma zinc during mild surgical stress in the rat

Zinc is an essential trace element and cofactor for many cellular processes. Uptake of ionized divalent zinc (Zn(2+)) in peripheral tissues depends on its total content in the circulation and on mechanisms facilitating delivery to tissues in its labile form. Understanding mechanisms of Zn(2+) delivery has been hindered by the absence of techniques to detect labile Zn(2+) in the circulation. In this study, we report the use of the fluorescent zinc-binding dye (ZnAF-2) to detect changes in labile Zn(2+) in the circulating plasma of the rat under standardized conditions, including exogenous infusions to increase plasma Zn(2+) and an infusion of the chelator, citrate, to decrease labile Zn(2+) in the plasma without altering total Zn(2+) content. In a model of mild surgical stress (unilateral femoral arterial ligation), plasma levels of total and labile Zn(2+) decreased significantly 24 h after the operation. Ultrafiltration of plasma into high- and low-molecular weight macromolecule fractionations indicated that binding capacity of zinc in the high-molecular weight fraction is impaired for the entire 24-h interval after induction of mild surgical stress. Affinity of the filtrate fraction was rapidly and reversibly responsive to anesthesia alone, decreasing significantly at 4 h and recovering at 24 h; in animals subjected to moderate surgical stress, this responsiveness was lost. These findings are the first reported measurements of labile Zn(2+) in the circulation in any form of mild systemic stress. Zinc undergoes substantial redistribution in the plasma as a response to surgical stress, leading to increased availability in lower molecular weight fractions and in its labile form.

Antioxidant pre-treatment prevents omeprazole-induced toxicity in an in vitro model of infectious gastritis

Omeprazole is a mainstay of therapy for gastroesophageal reflux disease (GERD) and gastritis, and is increasingly used as an over-the-counter remedy for dyspepsia. Omeprazole acts by selectively oxidizing thiol targets in the gastric proton pump, but it also appears to be toxic to the gastric mucosa. We hypothesized that omeprazole toxicity is due to non-specific oxidation of cell structures other than the proton pump, and tested the efficacy of antioxidants to prevent omeprazole-induced toxicity in isolated rabbit gastric glands. Toxicity was measured by uptake and converstion of calcein-AM, following three hours of exposure to omeprazole and a non-selective thiol-oxidant, monochloramine. Intracellular concentration of Zn(2+) and the capacity to maintain luminal acidity were monitored using the fluorescent reporters fluozin-3 and Lysosensor DND-160, respectively. Both omeprazole and monochloramine caused marked reduction in cell viability. The toxicity of omeprazole was independent of monochloramine toxicity. The thiol reducing agent dithiothreitol protected gastric glands from injury. The oxidant scavenger Vitamin C also protected, and did not impair the anti-secretory effects of omeprazole. Thus, omeprazole toxicity appears to be oxidative and preventable with antioxidant therapy, including Vitamin C. Vitamin C may be a safe and efficacious addition to treatments requiring the use of PPIs.