Correction: Cyclooxygenase pathway mediates the inhibition of Na-glutamine co-transporter B0AT1 in rabbit villus cells during chronic intestinal inflammation

[This corrects the article DOI: 10.1371/journal.pone.0203552.].

Maternal and Neonatal Outcomes in Women with Metabolic Syndrome and Substance Use Disorder

INTRODUCTION

Metabolic syndrome amplifies the risk of gestational diabetes, preeclampsia, and preterm labor in pregnant women. Similarly, women with substance use disorder have worsened obstetric and birth outcomes. Despite these two conditions being major healthcare disparities in Appalachia, the health outcomes of this cohort have not been studied thus far. This study looks at the health outcomes of this cohort.

METHOD AND RESULTS

In this retrospective cohort study, we analyzed 27,955 mothers who delivered at Cabell Huntington Hospital between January 2010 and November 2021. We implemented Chi-square tests to determine the associations and multiple logistic regression methods for comparison after controlling for other factors, and found that MetS, together with SUD, significantly increases the risk as well as the number of pregnancy complications such as gestational diabetes (p-value < 0.001), preeclampsia (p-value < 0.001), premature rupture (p-value < 0.001), preterm labor (p-value < 0.001), and newborn disorder (p-value < 0.001) compared to the women who had none or had either MetS or SUD alone.

CONCLUSION

Women with both metabolic syndrome and substance abuse had worsened pregnancy and neonatal outcomes compared to women with metabolic syndrome or SUD alone. In conclusion, analysis of all the variables is crucial to strategically planning and implementing health interventions that will positively influence the health outcome of the pregnant woman as well as the child.

The Role of Gut Microbiota and Metabolites in Obesity-Associated Chronic Gastrointestinal Disorders

The gut microbiota is a complex community of microorganisms that has become a new focus of attention due to its association with numerous human diseases. Research over the last few decades has shown that the gut microbiota plays a considerable role in regulating intestinal homeostasis, and disruption to the microbial community has been linked to chronic disease conditions such as inflammatory bowel disease (IBD), colorectal cancer (CRC), and obesity. Obesity has become a global pandemic, and its prevalence is increasing worldwide mostly in Western countries due to a sedentary lifestyle and consumption of high-fat/high-sugar diets. Obesity-mediated gut microbiota alterations have been associated with the development of IBD and IBD-induced CRC. This review highlights how obesity-associated dysbiosis can lead to the pathogenesis of IBD and CRC with a special focus on mechanisms of altered absorption of short-chain fatty acids (SCFAs)

Molecular Mechanism of Stimulation of Na-K-ATPase by Leukotriene D4 in Intestinal Epithelial Cells

Na-K-ATPase provides a favorable transcellular Na gradient required for the functioning of Na-dependent nutrient transporters in intestinal epithelial cells. The primary metabolite for enterocytes is glutamine, which is absorbed via Na-glutamine co-transporter (SN2; SLC38A5) in intestinal crypt cells. SN2 activity is stimulated during chronic intestinal inflammation, at least in part, secondarily to the stimulation of Na-K-ATPase activity. Leukotriene D4 (LTD4) is known to be elevated in the mucosa during chronic enteritis, but the way in which it may regulate Na-K-ATPase is not known. In an in vitro model of rat intestinal epithelial cells (IEC-18), Na-K-ATPase activity was significantly stimulated by LTD4. As LTD4 mediates its action via Ca-dependent protein kinase C (PKC), Ca levels were measured and were found to be increased. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, also mediated stimulation of Na-K-ATPase like LTD4, while BAPTA-AM (Ca chelator) and calphostin-C (Cal-C; PKC inhibitor) prevented the stimulation of Na-K-ATPase activity. LTD4 caused a significant increase in mRNA and plasma membrane protein expression of Na-K-ATPase α1 and β1 subunits, which was prevented by calphostin-C. These data demonstrate that LTD4 stimulates Na-K-ATPase in intestinal crypt cells secondarily to the transcriptional increase of Na-K-ATPase α1 and β1 subunits, mediated via the Ca-activated PKC pathway.

The Adipose Tissue-Derived Secretome (ADS) in Obesity Uniquely Induces L-Type Amino Acid Transporter 1 (LAT1) and mTOR Signaling in Estrogen-Receptor-Positive Breast Cancer Cells

Obesity increases the risk of postmenopausal breast cancer (BC). This risk is mediated by obesity-induced changes in the adipose-derived secretome (ADS). The pathogenesis of BC in obesity is stimulated by mTOR hyperactivity. In obesity, leucine might support mTOR hyperactivity. Leucine uptake by BC cells is through L-Type Amino Acid Transporter 1 (LAT1). Our objective was to link obesity-ADS induction of LAT1 to the induction of mTOR signaling. Lean- and obese-ADS were obtained from lean and obese mice, respectively. Breast ADS was obtained from BC patients. Estrogen-receptor-positive BC cells were stimulated with ADS. LAT1 activity was determined by uptake of 3H-leucine. The LAT1/CD98 complex, and mTOR signaling were assayed by Western blot. The LAT1 antagonists, BCH and JPH203, were used to inhibit LAT1. Cell migration and invasion were measured by Transwell assays. The results showed obese-ADS-induced LAT1 activity by increasing transporter affinity for leucine. Consistent with this mechanism, LAT1 and CD98 expression were unchanged. Induction of mTOR by obese-ADS was inhibited by LAT1 antagonists. Breast ADS from patients with BMIs > 30 stimulated BC cell migration and invasiveness. Collectively, our findings show that obese-ADS induction of LAT1 supports mTOR hyperactivity in luminal BC cells.

Unique Regulation of Coupled NaCl Absorption by Inducible Nitric Oxide in a Spontaneous SAMP1/YitFc Mouse Model of Chronic Intestinal Inflammation

In the small intestine, Na:H (NHE3) and Cl:HCO3 (DRA or PAT1) exchangers present in the brush border membrane (BBM) of absorptive villus cells are primarily responsible for the coupled absorption of NaCl, the malabsorption of which causes diarrhea, a common symptom of inflammatory bowel disease (IBD). Inducible nitric oxide (iNO), a known mediator of inflammation, is increased in the mucosa of the chronically inflamed IBD intestine. An SAMP1/YitFc (SAMP1) mouse, a spontaneous model of chronic ileitis very similar to human IBD, was used to study alterations in NaCl absorption. The SAMP1 and control AKR mice were treated with I-N(6)-(1-Iminoethyl)-lysine (L-NIL) to inhibit iNO production, and DRA/PAT1 and NHE3 activities and protein expression were studied. Though Na:H exchange activity was unaffected, Cl:HCO3 activity was significantly decreased in SAMP1 mice due to a reduction in its affinity for Cl, which was reversed by L-NIL treatment. Though DRA and PAT1 expressions were unchanged in all experimental conditions, phosphorylation studies indicated that DRA, not PAT1, is affected in SAMP1. Moreover, the altered phosphorylation levels of DRA was restored by L-NIL treatment. Inducible NO mediates the inhibition of coupled NaCl absorption by decreasing Cl:HCO3 but not Na:H exchange. Specifically, Cl:HCO3 exchanger DRA but not PAT1 is regulated at the level of its phosphorylation by iNO in the chronically inflamed intestine.

Mechanism of Na-K-ATPase Inhibition by PGE2 in Intestinal Epithelial Cells

The primary means of intestinal absorption of nutrients by villus cells is via Na-dependent nutrient co-transporters located in the brush border membrane (BBM). These secondary active co-transport processes require a favorable transcellular Na gradient that is provided by Na-K-ATPase. In chronic enteritis, malabsorption of essential nutrients is partially due to inhibition of villus Na-K-ATPase activity mediated by specific immune inflammatory mediators that are known to be elevated in the inflamed mucosa. However, how Prostaglandin E2 (PGE2), a specific mediator of nutrient malabsorption in the villus BBM, may mediate the inhibition of Na-K-ATPase is not known. Therefore, this study aimed to determine the effect of PGE2 on Na-K-ATPase in villus cells and define its mechanism of action. In vitro, in IEC-18 cells, PGE2 treatment significantly reduced Na-K-ATPase activity, accompanied by a significant increase in the intracellular levels of cyclic Adenosine Monophosphate (cAMP). The treatment with cAMP analog 8-Bromo-cAMP mimicked the PGE2-mediated effect on Na-K-ATPase activity, while Rp-cAMP (PKA inhibitor) pretreatment reversed the same. The mechanism of inhibition of PGE2 was secondary to a transcriptional reduction in the Na-K-ATPase α1 and β1 subunit genes, which was reversed by the Rp-cAMP pretreatment. Thus, the PGE2-mediated activation of the PKA pathway mediates the transcriptional inhibition of Na-K-ATPase activity in vitro.

Mast Cell Mediated Regulation of Small Intestinal Chloride Malabsorption in SAMP1/YitFc Mouse Model of Spontaneous Chronic Ileitis

In Inflammatory Bowel Disease (IBD), malabsorption of electrolytes (NaCl) results in diarrhea. Inhibition of coupled NaCl absorption, mediated by the dual operation of Na:H and Cl:HCO₃ exchangers on the brush border membrane (BBM) of the intestinal villus cells has been reported in IBD. In the SAMP1/YitFcs (SAMP1) mice model of spontaneous ileitis, representing Crohn’s disease, DRA (Downregulated in Adenoma) mediated Cl:HCO₃ exchange was shown to be inhibited secondary to diminished affinity of the exchanger for Cl. However, NHE3 mediated Na:H exchange remained unaffected. Mast cells and their secreted mediators are known to be increased in the IBD mucosa and can affect intestinal electrolyte absorption. However, how mast cell mediators may regulate Cl:HCO₃ exchange in SAMP1 mice is unknown. Therefore, the aim of this study was to determine the effect of mast cell mediators on the downregulation of DRA in SAMP1 mice. Mast cell numbers and their degranulation marker enzyme (β-hexosaminidase) levels were significantly increased in SAMP1 mice compared to control AKR mice. However, treatment of SAMP1 mice with a mast cell stabilizer, ketotifen, restored the β-hexosaminidase enzyme levels to normal in the intestine, demonstrating stabilization of mast cells by ketotifen. Moreover, downregulation of Cl:HCO₃ exchange activity was restored in ketotifen treated SAMP1 mice. Kinetic studies showed that ketotifen restored the altered affinity of Cl:HCO₃ exchange in SAMP1 mice villus cells thus reinstating its activity to normal. Further, RT-qPCR, Western blot and immunofluorescence studies showed that the expression levels of DRA mRNA and BBM protein, respectively remained unaltered in all experimental conditions, supporting the kinetic data. Thus, inhibition of Cl:HCO₃ exchange resulting in chloride malabsorption leading to diarrhea in IBD is likely mediated by mast cell mediators.

Moderate Alcohol Consumption Uniquely Regulates Sodium-Dependent Glucose Co-Transport in Rat Intestinal Epithelial Cells In Vitro and In Vivo

BACKGROUND

Chronic alcohol use often leads to malnutrition. However, how the intestinal absorption of nutrients such as glucose may be affected during moderate ethanol use has not been investigated. Glucose is absorbed via sodium (Na)-dependent glucose co-transport (SGLT1; SLC5A1) along the brush border membrane (BBM) of intestinal absorptive villus cells.

OBJECTIVE

The aim of this study was to investigate how moderate alcohol consumption affects the absorption of glucose via SGLT1.

METHODS

Intestinal epithelial cells (IEC-18; rat) were exposed to 8.64 mM ethanol over 1, 3, 6, and 12 h. Rats (16-wk-old, male, Sprague-Dawley) were administered 2 g/kg ethanol over 1, 3, and 6 h. Na-dependent 3H-O-methyl-d-glucose uptake was measured to assess SGLT1 activity. Na-K-ATPase activity was measured as a function of inorganic phosphate release. Protein expression was analyzed by Western blot analysis and immunohistochemical staining.

RESULTS

Ethanol significantly decreased Na-dependent glucose absorption in enterocytes in vitro (ethanol treatment: 48.4% of controls at 1 h; P < 0.01) and in vivo (ethanol treatment: 60.0% of controls at 1 h; P < 0.01). Na-K-ATPase activity was significantly inhibited in vitro (ethanol treatment: 36.9% of controls at 1 h; P < 0.01) and in vivo (ethanol treatment: 42.1% of controls at 1 h; P < 0.01). Kinetic studies showed that the mechanism of inhibition of Na-glucose co-transport was secondary to a decrease in the affinity (1/Km) of the co-transporter for glucose both in vitro and in vivo. Western blots and immunohistochemistry further demonstrated unaltered amounts of SGLT1 after ethanol treatment.

CONCLUSIONS

Moderate ethanol significantly decreases glucose absorption in IEC-18 cells and in villus cells of Sprague-Dawley rats. The inhibition of SGLT1 is secondary to an altered Na gradient at the cellular level and secondary to diminished affinity of the co-transporter for glucose at the protein level in the BBM. These observations may, at least in part, explain 1 possible mechanism of the onset of malnutrition associated with alcohol consumption.

Mechanisms of Regulation of Transporters of Amino Acid Absorption in Inflammatory Bowel Diseases

Intestinal absorption of dietary amino acids/peptides is essential for protein homeostasis, which in turn is crucial for maintaining health as well as restoration of health from significant diseases. Dietary amino acids/peptides are absorbed by unique transporter processes present in the brush border membrane of absorptive villus cells, which line the entire length of the intestine. To date, the only nutrient absorptive system described in the secretory crypt cells in the mammalian intestine is the one that absorbs the amino acid glutamine. Majority of the amino acid transporters are sodium dependent and therefore require basolateral membrane Na-K-ATPase to maintain an efficient transcellular Na gradient for their activity. These transport processes are tightly regulated by various cellular and molecular mechanisms that facilitate their optimal activity during normal physiological processes. Malabsorption of amino acids, recently described in pathophysiological states such as in inflammatory bowel disease (IBD), is undoubtedly responsible for the debilitating symptoms of IBD such as malnutrition, weight loss and ultimately a failure to thrive. Also recently, in vivo models of IBD and in vitro studies have demonstrated that specific immune-inflammatory mediators/pathways regulate specific amino acid transporters. This provides possibilities to derive novel nutrition and immune-based treatment options for conditions such as IBD. © 2020 American Physiological Society. Compr Physiol 10:673-686, 2020.

Inhibition of intestinal villus cell Na/K-ATPase mediates altered glucose and NaCl absorption in obesity-associated diabetes and hypertension

During obesity, diabetes and hypertension inevitably coexist and cause innumerable health disparities. In the obesity, diabetes, and hypertension triad (ODHT), deregulation of glucose and NaCl homeostasis, respectively, causes diabetes and hypertension. In the mammalian intestine, glucose is primarily absorbed by Na-glucose cotransport 1 (SGLT1) and coupled NaCl by the dual operation of Na-H exchange 3 (NHE3) and Cl-HCO3 [down-regulated in adenoma (DRA) or putative anion transporter 1 (PAT1)] exchange in the brush border membrane (BBM) of villus cells. The basolateral membrane (BLM) Na/K-ATPase provides the favorable transcellular Na gradient for BBM SGLT1 and NHE3. How these multiple, distinct transport processes may be affected in ODHT is unclear. Here, we show the novel and broad regulation by Na/K-ATPase of glucose and NaCl absorption in ODHT in multiple species (mice, rats, and humans). In vivo, during obesity inhibition of villus-cell BLM, Na/K-ATPase led to compensatory stimulation of BBM SGLT1 and DRA or PAT1, whereas NHE3 was unaffected. Supporting this new cellular adaptive mechanism, direct silencing of BLM Na/K-ATPase in intestinal epithelial cells resulted in selective stimulation of BBM SGLT1 and DRA or PAT1 but not NHE3. These changes will lead to an increase in glucose absorption, maintenance of traditional coupled NaCl absorption, and a de novo increase in NaCl absorption from the novel coupling of stimulated SGLT1 with DRA or PAT1. Thus, these novel observations provide the pathophysiologic basis for the deregulation of glucose and NaCl homeostasis of diabetes and hypertension, respectively, during obesity. These observations may lead to more efficacious treatment for obesity-associated diabetes and hypertension.-Palaniappan, B., Arthur, S., Sundaram, V. L., Butts, M., Sundaram, S., Mani, K., Singh, S., Nepal, N., Sundaram, U. Inhibition of intestinal villus cell Na/K-ATPase mediates altered glucose and NaCl absorption in obesity-associated diabetes and hypertension.

Unique Regulation of Na-K-ATPase during Growth and Maturation of Intestinal Epithelial Cells

Na-K-ATPase on the basolateral membrane provides the favorable transcellular Na gradient for the proper functioning of Na-dependent nutrient co-transporters on the brush border membrane (BBM) of enterocytes. As cells mature from crypts to villus, Na-K-ATPase activity doubles, to accommodate for the increased BBM Na-dependent nutrient absorption. However, the mechanism of increased Na-K-ATPase activity during the maturation of enterocytes is not known. Therefore, this study aimed to determine the mechanisms involved in the functional transition of Na-K-ATPase during the maturation of crypts to villus cells. Na-K-ATPase activity gradually increased as IEC-18 cells matured in vitro from day 0 (crypts) through day 4 (villus) of post-confluence. mRNA abundance and Western blot studies showed no change in the levels of Na-K-ATPase subunits α1 and β1 from 0 to 4 days post-confluent cells. However, Na-K-ATPase α1 phosphorylation levels on serine and tyrosine, but not threonine, residues gradually increased. These data indicate that as enterocytes mature from crypt-like to villus-like in culture, the functional activity of Na-K-ATPase increases secondary to altered affinity of the α1 subunit to extracellular K⁺, in order to accommodate the functional preference of the intestinal cell type. This altered affinity is likely due to increased phosphorylation of the α1 subunit, specifically at serine and tyrosine residues.

Stimulation of constitutive nitric oxide uniquely and compensatorily regulates intestinal epithelial cell brush border membrane Na absorption

In the mammalian small intestine, sodium is primarily absorbed by Na+ /H+ exchange (NHE3) and Na-glucose cotransport (SGLT1) in the brush border membrane (BBM) of villus cells. However, how enhanced cellular constitutive nitric oxide (cNO) may affect NHE3 and SGLT1 remains unclear. Both in vivo in rabbit intestinal villus cells and in vitro IEC-18 cells, administration of NO donor, GSNAP, modestly increased cNO. GSNAP stimulated SGLT1 in villus and IEC-18 cells. The mechanism of stimulation was secondary to an increase in the affinity of SGLT1 for glucose. The change in SGLT1 was not secondary to altered Na-extruding capacity of the cell since Na+ /K+ -ATPase was decreased by GSNAP treatment. In contrast, GSNAP inhibited NHE3 activity in villus cell BBM. The mechanism of NHE3 inhibition was secondary to reduced BBM transporter numbers. These studies demonstrated that the physiological increase in cNO uniquely regulates mammalian small intestinal NHE3 and SGLT1 to maintain Na homeostasis.

Cyclooxygenase pathway mediates the inhibition of Na-glutamine co-transporter B0AT1 in rabbit villus cells during chronic intestinal inflammation

In the mammalian intestine, glutamine assimilation by the absorptive villus cells is mediated by Na-glutamine co-transport, specifically by B0AT1. In a rabbit model of chronic intestinal inflammation, B0AT1 is inhibited secondary to a decrease in the number of co-transporters in the brush border membrane (BBM). This inhibition can be reversed by treatment with a broad-spectrum immune modulator such as glucocorticoid suggesting that immune inflammatory mediators may regulate B0AT1 during chronic intestinal inflammation. Arachidonic acid (AA) metabolites (AAM) are increased during chronic intestinal inflammation. However, whether AAM may regulate B0AT1 during chronic intestinal inflammation is unknown. Treatment of rabbits with ATK, to prevent the release of AAM reversed the inhibition of B0AT1. AAM are products of cyclooxygenase (COX) and/or lipoxygenase (LOX) pathways. Inhibition of COX with piroxicam, therefore reduction of prostaglandin formation in the chronically inflamed intestine, reversed the inhibition of B0AT1 to its normal levels. In contrast, inhibition of LOX with MK886, thus reduction of leukotriene formation during chronic enteritis, did not affect the inhibition of B0AT1. Kinetic studies showed that the mechanism of restoration of B0AT1 by ATK or piroxicam was secondary to the restoration of BBM co-transporter numbers. Western Blot analysis also demonstrated restoration of BBM B0AT1 co-transporter numbers. In conclusion, this study demonstrates that Na-glutamine co-transport mediated by B0AT1 in villus cells is regulated by prostaglandins rather than leukotrienes in the chronically inflamed intestine.

The Regulation and Function of the L-Type Amino Acid Transporter 1 (LAT1) in Cancer

The progression of cancer is associated with increases in amino acid uptake by cancer cells. Upon their entry into cells through specific transporters, exogenous amino acids are used to synthesize proteins, nucleic acids and lipids and to generate ATP. The essential amino acid leucine is also important for maintaining cancer-associated signaling pathways. By upregulating amino acid transporters, cancer cells gain greater access to exogenous amino acids to support chronic proliferation, maintain metabolic pathways, and to enhance certain signal transduction pathways. Suppressing cancer growth by targeting amino acid transporters will require an in-depth understanding of how cancer cells acquire amino acids, in particular, the transporters involved and which cancer pathways are most sensitive to amino acid deprivation. L-Type Amino Acid Transporter 1 (LAT1) mediates the uptake of essential amino acids and its expression is upregulated during the progression of several cancers. We will review the upstream regulators of LAT1 and the downstream effects caused by the overexpression of LAT1 in cancer cells.

Selective duodenography for controlled first-pass bolus distention of the duodenum in neonates and young children with bile-stained vomiting

AIM

To compare "selective duodenograms" performed through nasogastric tubes advanced into the proximal duodenum against traditional contrast studies regarding visualisation of a first-pass bolus distention of the duodenum and frequency of inconclusive results.

MATERIALS AND METHODS

Retrospective comparison of "selective duodenograms" and traditional upper gastrointestinal contrast studies in neonates with bile-stained vomiting, regarding demonstration of the duodenal C-loop, first-pass bolus capture, degree of distention of the duodenum, and number of inconclusive studies. Statistical comparison was performed using the two-tailed Fishers exact and chi-squared tests.

RESULTS

There were 31 "selective duodenograms" and 70 traditional studies. The C-loop was demonstrated in 93% of traditional studies versus 100% in "selective duodenograms" and was demonstrated significantly more often during the first-pass (94% versus 73%; p=0.018) and more often with distention of the duodenum for "selective duodenography" (94% versus 56%, p<0.001). There were more inconclusive traditional studies (7% versus 3%; non-significant).

CONCLUSION

Emergency upper gastrointestinal tract studies performed in neonates using the "selective duodenogram" technique demonstrated the duodenum with 100% success, with significantly more frequent first-pass bolus visualisation and duodenal distention than traditional studies. The five (7%) inconclusive traditional studies, present a significant diagnostic conundrum in the emergency setting because emergency surgery must be contemplated without proof.

Unique regulation of Na-glutamine cotransporter SN2/SNAT5 in rabbit intestinal crypt cells during chronic enteritis

The only Na‐nutrient cotransporter described in mammalian small intestinal crypt cells is SN2/SNAT5, which facilitates glutamine uptake. In a rabbit model of chronic intestinal inflammation, SN2 stimulation is secondary to an increase in affinity of the cotransporter for glutamine. However, the immune regulation of SN2 in the crypt cells during chronic intestinal inflammation is unknown. We sought to determine the mechanism of regulation of Na‐nutrient cotransporter SN2 by arachidonic acid metabolites in crypt cells. The small intestines of New Zealand white male rabbits were inflamed via inoculation with Eimeria magna oocytes. After 2‐week incubation, control and inflamed rabbits were subjected to intramuscular injections of arachidonyl trifluoromethyl ketone (ATK), piroxicam and MK886 for 48 hrs. After injections, the rabbits were euthanized and crypt cells from small intestines were harvested and used. Results: Treatment of rabbits with ATK prevented the release of AA and reversed stimulation of SN2. Inhibition of cyclooxygenase (COX) with piroxicam did not affect stimulation of SN2. However, inhibition of lipoxygenase (LOX) with MK886, thus reducing leukotriene formation during chronic enteritis, reversed the stimulation of SN2. Kinetic studies showed that the mechanism of restoration of SN2 by ATK or MK886 was secondary to the restoration of the affinity of the cotransporter for glutamine. For all treatment conditions, Western blot analysis revealed no change in SN2 protein levels. COX inhibition proved ineffective at reversing the stimulation of SN2. Thus, this study provides evidence that SN2 stimulation in crypt cells is mediated by the leukotriene pathway during chronic intestinal inflammation.

Multiple rainfall event pollution transport by sustainable drainage systems: the fate of fine sediment pollution

A key design criterion of sustainable urban drainage systems is to mitigate urban stormwater pollution. Current research defines sustainable urban drainage systems (SuDS) pollutant treatment efficiency through the detention of total suspended solids, urban nutrients and heavy metal pollutants within the system during a design flow event, with research focusing on sand (>2 mm) sediment movement. The impact of multiple rainfall-runoff events on the fine sediment (<2 mm) treatment efficiency of SuDS is not yet well defined, and the temporal movement of detained sediment has not been investigated in detail. The field research presented in this paper addresses this research gap, monitoring ongoing fine sediment transport through a best-practice-designed SuDS network over 12 months through the use of a novel rare earth oxide trace methodology. Through time-stepped monitoring of the fine sediment pollution across three SuDS treatment trains (networks), the following key conclusions have been drawn. (1) That fine sediment becomes re-suspended and re-deposited within SuDS assets and the network as a result of ongoing multiple rainfall-runoff events. (2) That this re-suspension continues for over 52 weeks. (3) That by area, linear wetlands (within the monitored networks) outperform wetland and swale assets in multiple event fine sediment detention. And (4) that multiple event monitoring and analysis of fine sediment within a SuDS network highlights the under-performance of SuDS assets against current design event expectations.

Aryl hydrocarbon receptor (AHR) regulation of L-Type Amino Acid Transporter 1 (LAT-1) expression in MCF-7 and MDA-MB-231 breast cancer cells

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that is regulated by environmental toxicants that function as AHR agonists such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). L-Type Amino Acid Transporter 1 (LAT1) is a leucine transporter that is overexpressed in cancer. The regulation of LAT1 by AHR in MCF-7 and MDA-MB-231 breast cancer cells (BCCs) was investigated in this report. Ingenuity pathway analysis (IPA) revealed a significant association between TCDD-regulated genes (TRGs) and molecular transport. Overlapping the TCDD-RNA-Seq dataset obtained in this study with a published TCDD-ChIP-seq dataset identified LAT1 as a primary target of AHR-dependent TCDD induction. Short interfering RNA (siRNA)-directed knockdown of AHR confirmed that TCDD-stimulated increases in LAT1 mRNA and protein required AHR expression. TCDD-stimulated increases in LAT1 mRNA were also inhibited by the AHR antagonist CH-223191. Upregulation of LAT1 by TCDD coincided with increases in leucine uptake by MCF-7 cells in response to TCDD. Chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assays revealed increases in AHR, AHR nuclear translocator (ARNT) and p300 binding and histone H3 acetylation at an AHR binding site in the LAT1 gene in response to TCDD. In MCF-7 and MDA-MB-231 cells, endogenous levels of LAT1 mRNA and protein were reduced in response to knockdown of AHR expression. Knockdown experiments demonstrated that proliferation of MCF-7 and MDA-MB-231 cells is dependent on both LAT1 and AHR. Collectively, these findings confirm the dependence of cancer cells on leucine uptake and establish a mechanism for extrinsic and intrinsic regulation of LAT1 by AHR.

Mast cell regulation of Na-glutamine co-transporters B0AT1 in villus and SN2 in crypt cells during chronic intestinal inflammation

Background

In the chronically inflamed rabbit small intestine, brush border membrane (BBM) Na-glutamine co-transport is inhibited in villus cells (mediated by B0AT1), while it is stimulated in crypt cells (mediated by SN2/SNAT5). How mast cells, known to be enhanced in the chronically inflamed intestine, may regulate B0AT1 in villus and SN2/SNAT5 in crypt cell is unknown. Thus, the aim of the present study is to determine the regulation of B0AT1 and SN2/SNAT5 by mast cells during chronic enteritis.

Methods

Chronic intestinal inflammation was induced in male rabbits with intra-gastric inoculation of Eimeria magna oocytes. Rabbits with chronic inflammation were treated with ketotifen (10 mg/day) or saline (Placebo) for 2 days. Villus and crypts cells were isolated from the rabbit intestine using the Ca++ chelation technique. Na/K-ATPase activity was measured as Pi from cellular homogenate. BBM vesicles (BBMV) were prepared from villus and crypt cells and uptake studies were performed using rapid filtration technique with ³H-Glutamine. Western blot analyses were done using B0AT1 and SN2 specific antibodies.

Results

In villus cells, Na-glutamine co-transport inhibition observed during inflammation was completely reversed by ketotifen, a mast cell stabilizer. In contrast, in crypt cells, Na-glutamine co-transport stimulation was reversed to normal levels by ketotifen. Kinetic studies demonstrated that ketotifen reversed the inhibition of B0AT1 in villus cells by restoring co-transporter numbers in the BBM, whereas the stimulation of SN2/SNAT5 in crypts cells was reversed secondary to restoration of affinity of the co-transporter. Western blot analysis showed that ketotifen restored immune-reactive levels of B0AT1 in villus cells, while SN2/SNAT5 levels from crypts cell remained unchanged.

Conclusion

In the present study we demonstrate that mast cells likely function as a common upstream immune pathway regulator of the Na-dependent glutamine co-transporters, B0AT1 in villus cells and SN2 in crypts cells that are uniquely altered in the chronically inflamed small intestine.

Chronic and selective inhibition of basolateral membrane Na-K-ATPase uniquely regulates brush border membrane Na absorption in intestinal epithelial cells

Na-K-ATPase, an integral membrane protein in mammalian cells, is responsible for maintaining the favorable intracellular Na gradient necessary to promote Na-coupled solute cotransport processes [e.g., Na-glucose cotransport (SGLT1)]. Inhibition of brush border membrane (BBM) SGLT1 is, at least in part, due to the diminished Na-K-ATPase in villus cells from chronically inflamed rabbit intestine. The aim of the present study was to determine the effect of Na-K-ATPase inhibition on the two major BBM Na absorptive pathways, specifically Na-glucose cotransport and Na/H exchange (NHE), in intestinal epithelial (IEC-18) cells. Na-K-ATPase was inhibited using 1 mM ouabain or siRNA for Na-K-ATPase-α1 in IEC-18 cells. SGLT1 activity was determined as 3-O-methyl-D-[(3)H]glucose uptake. Na-K-ATPase activity was measured as the amount of inorganic phosphate released. Treatment with ouabain resulted in SGLT1 inhibition at 1 h but stimulation at 24 h. To further characterize this unexpected stimulation of SGLT1, siRNA silencing was utilized to inhibit Na-K-ATPase-α1. SGLT1 activity was significantly upregulated by Na-K-ATPase silencing, while NHE3 activity remained unaltered. Kinetics showed that the mechanism of stimulation of SGLT1 activity was secondary to an increase in affinity of the cotransporter for glucose without a change in the number of cotransporters. Molecular studies demonstrated that the mechanism of stimulation was not secondary to altered BBM SGLT1 protein levels. Chronic and direct silencing of basolateral Na-K-ATPase uniquely regulates BBM Na absorptive pathways in intestinal epithelial cells. Specifically, while BBM NHE3 is unaffected, SGLT1 is stimulated secondary to enhanced affinity of the cotransporter.

Inducible nitric oxide regulates intestinal glutamine assimilation during chronic intestinal inflammation

To facilitate assimilation of glutamine, different Na-dependent glutamine absorptive pathways are present in the rabbit small intestine, specifically B0AT1 in villus and SN2 in crypt cell brush border membrane. Further, both are uniquely regulated in the chronically inflamed intestine. B0AT1 is inhibited secondary to reduced number of brush border membrane (BBM) co-transporters while SN2 is stimulated secondary to an increased affinity for glutamine. These unique changes are reversible by treatment with a broad spectrum immune modulator such as glucocorticoids. However, whether inducible nitric oxide (iNO), known to be elevated in the mucosa of the chronically inflamed intestine, may be responsible for these co-transporter alterations is not known. In the present study, treatment of chronically inflamed rabbits with L-NIL, a selective inhibitor of iNO synthase, reversed the inhibition of B0AT1 in villus and the stimulation of SN2 in crypt cells. At the level of the co-transporter in the brush border membrane, inhibition of iNO production reversed the inhibition of villus B0AT1 by restoring the co-transporter numbers while the stimulation of crypt SN2 was reversed back to normal by restoring its affinity for glutamine. Western blot analyses of BBM proteins also confirmed the kinetic studies. Thus, L-NIL treatment restores the uniquely altered Na-glutamine co-transporters in the enterocytes of chronically inflamed intestine. All these data indicate that iNO functions as an upstream immune modulator directly regulating glutamine assimilation during chronic intestinal inflammation.

Protein kinase C-mediated phosphorylation of RKIP regulates inhibition of Na-alanine cotransport by leukotriene D(4) in intestinal epithelial cells

Leukotriene D4 (LTD4) is an important immune inflammatory mediator that is known to be elevated in the mucosa of chronically inflamed intestine and alter nutrient absorption. LTD4 inhibits Na-alanine cotransport in intestinal epithelial cells by decreasing the affinity of the cotransporter ASCT1. LTD4 is known to increase intracellular Ca(++) and cAMP concentrations. However, the intracellular signaling mechanism of LTD4-mediated ASCT1 inhibition is unknown. In the present study, pretreatment with calcium chelator BAPTA-AM or inhibition of Ca(++)-dependent protein kinase C (PKC), specifically PKCα, resulted in the reversal of LTD4-mediated inhibition of ASCT1, revealing the involvement of the Ca(++)-activated PKC pathway. PKCα is known to phosphorylate Raf kinase inhibitor protein (RKIP), thus activating its downstream signaling pathway. Immunoblotting with anti-RKIP-Ser(153) antibody showed an increase in phosphorylation levels of RKIP in LTD4-treated cells. Downregulation of endogenous RKIP showed no decrease in ASCT1 activity by LTD4, thus confirming its involvement in ASCT1 regulation. Phosphorylation of RKIP by PKC is known to activate different signaling pathways, and in this study it was found to activate cAMP-activated protein kinase A (PKA) pathway. Although protein abundance of ASCT1 was not altered in any of the experimental conditions, there was an increase in the levels of phosphothreonine in ASCT1 protein, thus showing that phosphorylation changes were responsible for the altered affinity of ASCT1 by LTD4. In conclusion, LTD4 inhibits ASCT1 through PKC-mediated phosphorylation of RKIP, leading to the subsequent activation of PKA pathway, possibly through β2-andrenergic receptor activation.

Cardiac responses to 24 hrs hyperoxia in Bmp2 and Bmp4 heterozygous mice

BACKGROUND

Hyperoxia or clinical oxygen (O2) therapy is known to result in increased oxidative burden. Therefore, understanding susceptibility to hyperoxia exposure is clinically important. Bone morphogenetic proteins (BMPs) 2 and 4 are involved in cardiac development and may influence responses to hyperoxia.

METHODS

Bmp2(+/)(-). Bmp4(+/)(-) and wild-type mice were exposed to hyperoxia (100% O2) for 24 hrs. Electrocardiograms (ECG) were recorded before and during exposure by radio-telemetry.

RESULTS

At baseline, a significantly higher low frequency (LF) and total power (TP) heart rate variability (HRV) were found in Bmp2(+/)(-) mice only (p < 0.05). Twenty-four hours hyperoxia-induced strain-independent reductions in heart rate, QTcB and ST-interval and increases in QRS, LF HRV and standard deviation of RR-intervals were observed. In Bmp4(+/)(-) mice only, increased PR-interval (PR-I) (24 hrs), P-wave duration (P-d; 18 and 21-24 hrs), PR-I minus P-d (PR - Pd; 24 hrs) and root of the mean squared differences of successive RR-intervals (24 hrs) were found during hyperoxia (p < 0.05).

DISCUSSION

Elevated baseline LF and TP HRV in Bmp2(+/)(-) mice suggests an altered autonomic nervous system regulation of cardiac function in these mice. However, this was not related to strain specific differences in responses to 24 hrs hyperoxia. During hyperoxia, Bmp4(+/-) mice were the most susceptible in terms of atrioventricular conduction changes and risk of atrial fibrillation, which may have important implications for patients treated with O2 who also harbor Bmp4 mutations. This study demonstrates significant ECG and HRV responses to 24 hrs hyperoxia in mice, which highlights the need to further work on the genetic mechanisms associated with cardiac susceptibility to hyperoxia.

Regulation of sodium-glutamine cotransport in villus and crypt cells by glucocorticoids during chronic enteritis

BACKGROUND

Assimilation of the preferred nutrient of enterocytes is mediated primarily by sodium (Na)-dependent cotransport (NGct) in the intestine. The predominant NGcT in villus cells, B0AT1, is inhibited secondary to a decrease in cotransporter numbers during chronic intestinal inflammation. In contrast, NGcT mediated by SN2 in crypt cells is stimulated secondary to increased affinity of the cotransporter for glutamine during chronic ileitis. Glucocorticoid is a mainstay of treatment for inflammatory bowel disease. However, its effect on NGcT is not known.

METHODS

The inhibition of B0AT1 in villus cells during chronic intestinal inflammation was reversed back to normal by methylprednisolone (MP). This was secondary to the restoration of the cotransporter numbers in the brush border membrane rather than an alteration in the affinity. The stimulation of NGcT in crypt cells during chronic ileitis was also restored back to its normal levels by MP treatment. This reversal was secondary to the restoration of the altered affinity of the cotransporter SN2 for glutamine.

RESULTS

Kinetic studies and western blot analysis were consistent with functional studies for both cotransporters. Thus, glucocorticoids restore two uniquely altered Na-glutamine cotransporters, B0AT1 in villus and SN2 in crypt cells during chronic enteritis.

CONCLUSIONS

These data indicate that glucocorticoids function as an upstream broad spectrum immune modulator in the chronically inflamed intestine.

Na-glutamine co-transporters B(0)AT1 in villus and SN2 in crypts are differentially altered in chronically inflamed rabbit intestine

Glutamine is a major nutrient utilized by the intestinal epithelium and is primarily assimilated via Na-glutamine co-transport (NGcT) on the brush border membrane (BBM) of enterocytes. Recently we reported that B(0)AT1 (SLC6A19) mediates glutamine absorption in villus while SN2 (SLC38A5) does the same in crypt cells. However, how B(0)AT1 and SN2 are affected during intestinal inflammation is unknown. In the present study it was shown that during chronic enteritis NGcT was inhibited in villus cells, however, it was stimulated in crypt cells. Our studies also demonstrated that the mechanism of inhibition of NGcT during chronic enteritis was secondary to a reduction in the number of B(0)AT1 co-transporters in the villus cell BBM without a change in the affinity of the co-transporter. In contrast, stimulation of NGcT in crypt cells was secondary to an increase in the affinity of SN2 for glutamine without an alteration in the number of co-transporters. Thus, glutamine assimilation which occurs via distinct transporters in crypt and villus cells is altered in the chronically inflamed intestine.

Runoff infiltration, a desktop case study

The use of sustainable drainage systems (SuDS) or best management practice is becoming increasingly common. However, rather than adopting the preferred 'treatment train' implementation, many developments opt for end-of-pipe control ponds. This paper discusses the use of SUDS in series to form treatment trains and compares their potential performance and effectiveness with end-of-pipe solutions. Land-use, site and catchment characteristics have been used alongside up-to-date guidance, Infoworks CS and MUSIC to determine whole-life-costs, land-take, water quality and quantity for different SuDS combinations. The results presented show that the use of a treatment train allows approaches differing from the traditional use of single SuDS, either source or 'end-of-pipe', to be proposed to treat and attenuate runoff. The outcome is a more flexible solution where the footprint allocated to SUDS, costs and water quality can be managed differently to fully meet stakeholder objectives.

Prioritising sewerage maintenance using inferred sewer age: a case study for Edinburgh

The reported research project focuses on using a database which contains details of customer contacts and CCTV data for a key Scottish catchment to construct a GIS based sewer condition model. Given the nature of the asset registry, a key research challenge was estimating the age of individual lengths of pipe. Within this context, asset age was inferred using the estimated age of surface developments-this involved overlaying the network in a GIS with historical digital maps. The paper illustrates that inferred asset age can reliably be used to highlight assets which are more likely to fail.

The holistic prioritisation of proactive sewer maintenance

In sewerage asset management, there has been a concerted move away from primarily assessing system capacity or physical performance, to focus on "serviceability" as a key performance indicator. After identifying flooding due to blockages as a key failure mode, this paper documents the development of a tool which can contribute towards efficient sewerage asset management within the context of maintaining "serviceability" to customers, the public and the environment. Against the background of poor availability of reliable data, the reported project provides a process based on FMECA which can be implemented with limited information and without the need for additional data gathering. Land use and network characteristics data have been used alongside a hydrodynamic model to determine critical points in a network. Based on this, a methodology for identifying where blockage likelihood lies is outlined alongside an approach which allows failure consequence to be quantified. The text then outlines a framework which allows failure likelihood and consequence to be combined to prioritise sewerage asset maintenance.

Identification and characterization of rabbit small intestinal villus cell brush border membrane Na-glutamine cotransporter

Glutamine, the primary metabolic fuel for the mammalian small intestinal enterocytes, is primarily assimilated by Na-amino acid cotransporters. Although Na-solute cotransport has been shown to exist in the brush border membrane (BBM) of the absorptive villus cells, the identity of Na-glutamine cotransport in rabbit small intestinal villus cells was unknown. Na-dependent glutamine uptake is present in villus BBM vesicles. An intravesicular proton gradient did not stimulate this Na-dependent glutamine uptake, whereas Li+ did not significantly suppress this uptake. These observations in concert with amino acid substitution studies suggested that Na-glutamine cotransporter in the villus cell BBM was the newly identified cotransporter B0AT1 (SLC6A19). Quantitative real-time PCR identified the message for this cotransporter in villus cells. Thus a full-length cDNA of B0AT1 was cloned and expressed in MDA-MB-231 cells. This expressed cotransporter exhibited characteristics similar to those observed in villus cells from the rabbit small intestine. Antibody was generated for B0AT1 that demonstrated the presence of this cotransporter protein in the villus cell BBM. Kinetic studies defined the kinetic parameters of this cotransporter. Thus this study describes the identification, cloning, and characterization of the Na-amino acid cotransporter responsible for the assimilation of a critical amino acid by the absorptive villus cells in the mammalian small intestine.

Population genetic structure of North American thinhorn sheep (Ovis dalli)

The thinhorn sheep (Ovis dalli ssp.) provides a rare example of a North American large mammal that occupies most of its native range and maintains close to ancestral population size. There are currently two recognized subspecies, Dall's sheep (O. d. dalli) and Stone's sheep (O. d. stonei), the validity of which remains uncertain. We investigated the spatial genetic structure of thinhorn sheep populations representing both subspecies by genotyping individuals (n = 919) from across the species range at 12 variable microsatellite loci. We found high levels of genetic diversity within (HE = 0.722) and significant genetic structure among the 24 sampled areas (FST = 0.160). Genetic distance measures and Bayesian clustering analyses revealed the presence of at least eight subpopulations that are delineated by mountain range topology. A strong overall pattern of isolation-by-distance is evident across the sampling range (r = 0.75, P < 0.001) suggesting limited dispersal and extensive philopatry. Partial Mantel tests of this relationship showed mountain range distinctions represent significant barriers to gene flow (P = 0.0001), supporting the Bayesian analyses. Genetic structure was more strongly pronounced in southern Yukon and Alaska than elsewhere. We also show evidence for genetic differences between the two currently recognized thinhorn subspecies.

Flies and fish: birds of a feather

The identification of specific clock-containing structures has been a major endeavour of the circadian field for many years. This has lead to the identification of many key components of the circadian system, including the suprachiasmatic nucleus in mammals, and the eyes and pineal glands in lower vertebrates. However, the idea that these structures represent the only clocks in animals has been challenged by the discovery of peripheral pacemakers in most organs and tissues, and even a number of cell lines. In Drosophila, and vertebrates such as the zebrafish, these peripheral clocks appear to be highly autonomous, being set directly by the environmental light/dark cycle. However, a hierarchy of clocks may still exist in mammals. In this review, we examine some of the current views regarding peripheral clocks, their organization and how they are entrained.

Scedosporium prolificans keratouveitis in association with a contact lens retained intraocularly over a long term

Scedosporium prolificans is a soil saprophyte that is associated with a large variety of infectious processes and with respiratory colonization in immunocompetent and immunocompromised patients. We report the first described case of S. prolificans keratouveitis associated with the intraocular long-term retention of a contact lens in a 76-year-old female patient.

The effects of chloroquine on bleeding time and disappearance of platelet 5-hydroxytryptamine in rabbits

BACKGROUND

Chloroquine inhibits platelet aggregation in vitro and in vivo. Because inhibition of platelet aggregation may prolong bleeding time, the effect of chloroquine administration on bleeding time and disappearance of platelet serotonin, which may affect bleeding time, were studied.

METHODS AND RESULTS

Platelets were harvested from 12 rabbits. They were labelled with (111)In to tag individual platelets and (14)C-labelled 5-hydroxytryptamine (5HT) or serotonin. Doubly labelled platelets from the rabbits were returned to their donors. At timed intervals, from 2 to 66 hours, blood samples were drawn and platelets collected. (111)In and (14)C were separately counted. In 6 experiments, the animals served as control and received normal saline intraperitoneally (IP) daily for 4 days; the other 6 rabbits served as test and were given a therapeutic dose of chloroquine phosphate (10 mg/kg, IP) daily for 4 days. Indium disappeared in an exponential fashion in both control and test groups. The fraction of indium disappearing per hour was significantly less in chloroquine-treated rabbits than in control rabbits (P <.001). Ninety-nine percent of the indium-labelled platelets disappeared in 7.0 days in chloroquine-treated rabbits and 5.8 days in control rabbits (P <.001). Bleeding times in chloroquine-treated and control rabbits were not significantly different (64.8 +/- 2.2 vs. 62.3 +/- 4.0 sec, respectively). However, the labelled platelet serotonin disappeared more slowly in chloroquine-treated rabbits than in control rabbits. (K for chloroquine-treated and control rabbits was 0.0096 +/- 0.0064 and 0. 0254 +/- 0.0016; respectively, P <.001).

CONCLUSION

Chloroquine prolongs platelet survival but does not affect bleeding time in rabbits. Chloroquine also slows down the disappearance of labelled platelet serotonin. We propose that chloroquine increases the recycling of platelet 5HT, passing it on from platelet to platelet in rabbits and this may have a role in the maintenance of hemostasis.

Interferon-induced reversible acute renal failure with nephrotic syndrome

Although there has been considerable experience with interferons in clinical trials during the past decade, acute renal failure as a side effect of interferon treatments has rarely been reported. We report a case in which acute renal failure with nephrotic syndrome was associated with therapy with two types of interferons. We note incomplete return of renal function upon withdrawal of therapy.

Hyperkalemia associated with intravenous labetalol therapy for acute hypertension in renal transplant recipients

Three renal transplant recipients developed potentially life-threatening hyperkalemia after receiving intravenous labetalol for postoperative hypertension. Even as beta-adrenergic agonists find increasing use in the therapy of acute hyperkalemia, physicians should be aware of the potential of beta blockers to cause profound elevations of serum potassium.

Decerebrate posturing with the syndrome of inappropriate secretion of antidiuretic hormone

Decerebrate and/or decorticate posturing have not yet been described as possible features of the syndrome of inappropriate secretion of antidiuretic hormone. Cerebral edema and loss of brain electrolytes are contributing factors resulting in altered excitability of the neural membrane. We describe a patient who, on the eighth day after a head injury, presented with decerebrate posturing, which coincided with the development of the syndrome of inappropriate secretion of antidiuretic hormone, and which rapidly reversed with the correction of the hyponatremia. We believe that the syndrome of inappropriate secretion of antidiuretic hormone should be included in the differential diagnosis of abnormal posturing in the head-injured patient.