Potassium-Switch Signaling Pathway Dictates Acute Blood Pressure Response to Dietary Potassium

BACKGROUND

Potassium (K+)-deficient diets, typical of modern processed foods, increase blood pressure (BP) and NaCl sensitivity. A K+-dependent signaling pathway in the kidney distal convoluted tubule, coined the K+ switch, that couples extracellular K+ sensing to activation of the thiazide-sensitive NaCl cotransporter (NCC) and NaCl retention has been implicated, but causality has not been established.

METHODS

To test the hypothesis that small, physiological changes in plasma K+ (PK+) are translated to BP through the switch pathway, a genetic approach was used to activate the downstream switch kinase, SPAK (SPS1-related proline/alanine-rich kinase), within the distal convoluted tubule. The CA-SPAK (constitutively active SPS1-related proline/alanine-rich kinase mice) were compared with control mice over a 4-day PK+ titration (3.8-5.1 mmol) induced by changes in dietary K+. Arterial BP was monitored using radiotelemetry, and renal function measurements, NCC abundance, phosphorylation, and activity were made.

RESULTS

As PK+ decreased in control mice, BP progressively increased and became sensitive to dietary NaCl and hydrochlorothiazide, coincident with increased NCC phosphorylation and urinary sodium retention. By contrast, BP in CA-SPAK mice was elevated, resistant to the PK+ titration, and sensitive to hydrochlorothiazide and salt at all PK+ levels, concomitant with sustained and elevated urinary sodium retention and NCC phosphorylation and activity. Thus, genetically locking the switch on drives NaCl sensitivity and prevents the response of BP to potassium.

CONCLUSIONS

Low K+, common in modern ultraprocessed diets, presses the K+-switch pathway to turn on NCC activity, increasing sodium retention, BP, and salt sensitivity.

A comparative study on prophylactic efficacy of cinnarizine and amitriptyline in childhood migraine: a randomized double-blind clinical trial

BACKGROUND

Pediatric migraine prophylaxis is indicated when headaches are frequent and/or disabling. We aimed to conduct a study to compare the efficacy of cinnarizine and amitriptyline in pediatric migraine prophylaxis.

METHODS

In a randomized, double-blind trial, patients aged 4-17 years with migraine who were eligible for prophylaxis enrolled. The primary outcome was a reduction response rate of ≥50% with p < 0.005 with respect to headache characteristics. The secondary outcome was migraine disability assessment. We evaluated patients every four weeks for three months: T1: week 4, T2: week 8 and T3: week 12. The safety profile was also assessed.

RESULTS

Thirty patients were randomly assigned to each group. However, 43 patients completed the trial. Headache frequency decreased in amitriptyline group more effectively in T1 (p = 0.004). Amitriptyline was more successful in reducing the headache duration in all three periods (p < 0.005). There was no significant difference in severity improvement and reducing disability score between the two groups (p > 0.005). No serious adverse events were observed.

CONCLUSIONS

Both medications are effective in ameliorating migraine headaches and related disabilities. However, amitriptyline appears be a preferable option over cinnarizine, given its faster onset of action, efficacy in reducing headache duration and longer-lasting effects.Trial Registration: The study was registered with the Iranian Registry of Clinical Trials (IRCT) under the code IRCT-20191112045413N1.

Modifying Dietary Sodium and Potassium Intake: An End to the 'Salt Wars'?

Excessive salt intake raises blood pressure, but the implications of this observation for human health have remained contentious. It has also been recognized for many years that potassium intake may mitigate the effects of salt intake on blood pressure and possibly on outcomes such as stroke. Recent large randomized intervention trials have provided strong support for the benefits of replacing salt (NaCl) with salt substitute (75% NaCl, 25% KCl) on hard outcomes, including stroke. During the same period of time, major advances have been made in understanding how the body senses and tastes salt, and how these sensations drive intake. Additionally, new insights into the complex interactions between systems that control sodium and potassium excretion by the kidneys, and the brain have highlighted the existence of a potassium switch in the kidney distal nephron. This switch seems to contribute importantly to the blood pressure-lowering effects of potassium intake. In recognition of these evolving data, the United States Food and Drug Administration is moving to permit potassium-containing salt substitutes in food manufacturing. Given that previous attempts to reduce salt consumption have not been successful, this new approach has a chance of improving health and ending the 'Salt Wars'.

Have changing practices in salvage medical options affected colectomy rates in acute severe ulcerative colitis?

BACKGROUND

In 2014, infliximab (IFX) was listed on the Australian Pharmaceutical Benefits Scheme for acute severe ulcerative colitis (ASUC) and is now the preferred option for medical salvage, superseding cyclosporin A (CsA). Optimal dosing schedules for IFX remain unknown.

AIM

The authors aim to evaluate the effect of changing from predominantly CsA to almost exclusively IFX for the treatment of steroid-refractory ASUC on colectomy rates.

METHODS

A retrospective review was performed of patients admitted with ASUC between 2012 and 2020. Patients were categorised into two groups according to year of presentation - either 'historical treatment' cohort (2012-2014), when CsA was primarily used, or 'contemporary treatment' cohort (2014-2020), when IFX was mostly prescribed, in either standard or intensive doses.

RESULTS

One hundred thirty-nine patients were included; 37 in the historical treatment cohort and 102 in the contemporary treatment cohort. In the historical treatment cohort, 12 of 37 received salvage therapy and eight (67%) received CsA. In the contemporary treatment cohort, 49 of 102 patients received salvage therapy, 40 (82%) with IFX, of whom 22 (53%) received intensified doses. Colectomy rates were similar at 30 days, 6 months and 12 months between historical and contemporary treatment cohorts (14% vs 12% [P = 0.77], 19% vs 18% [P > 0.99],and 22% vs 18% [P = 0.63], respectively). Difference in 12-month colectomy rates between standard versus intensive IFX did not meet statistical significance (three of 21 [14%] vs nine of 22 [41%]. respectively; P = 0.09).

CONCLUSION

There was no difference in 30-day, 6-month or 12-month colectomy rates between the historical treatment and contemporary treatment cohorts. The use of IFX, rather than CsA, even at intensified dosing, does not appear to reduce the colectomy rate observed in our patients.

Advances in the Acute and Preventive Treatment of Pediatric Migraine

PURPOSE OF REVIEW

Headaches are common in children and adolescents. Treatments for debilitating migraine are often not FDA approved or lack evidence of efficacy for children. This narrative review looks at the evidence for acute and preventative pharmacologic and non-pharmacologic treatment of pediatric migraine, as well as reviewing any recent or ongoing clinical trials.

RECENT FINDINGS

Studies have been published on pharmacological treatments for headache, as well as non-pharmacological treatments. Recent findings in pediatric migraine using onabotulinumtoxinA, calcitonin gene related peptide antagonists, interventional procedures, and devices are reviewed. Pharmacologic as well as non-pharmacologic approaches for the prevention and treatment of migraine show safety and efficacy data that is promising. These treatments should be incorporated in a multi-modal approach to the management of pediatric migraine. Continued studies, prospective and randomized, are needed to further assess these newer treatments for migraine in the pediatric setting.

Dissociation of sodium-chloride cotransporter expression and blood pressure during chronic high dietary potassium supplementation

Dietary potassium (K+) supplementation is associated with a lowering effect in blood pressure (BP), but not all studies agree. Here, we examined the effects of short- and long-term K+ supplementation on BP in mice, whether differences depend on the accompanying anion or the sodium (Na+) intake and molecular alterations in the kidney that may underlie BP changes. Relative to the control diet, BP was higher in mice fed a high NaCl (1.57% Na+) diet for 7 weeks or fed a K+-free diet for 2 weeks. BP was highest on a K+-free/high NaCl diet. Commensurate with increased abundance and phosphorylation of the thiazide sensitive sodium-chloride-cotransporter (NCC) on the K+-free/high NaCl diet, BP returned to normal with thiazides. Three weeks of a high K+ diet (5% K+) increased BP (predominantly during the night) independently of dietary Na+ or anion intake. Conversely, 4 days of KCl feeding reduced BP. Both feeding periods resulted in lower NCC levels but in increased levels of cleaved (active) α and γ subunits of the epithelial Na+ channel ENaC. The elevated BP after chronic K+ feeding was reduced by amiloride but not thiazide. Our results suggest that dietary K+ has an optimal threshold where it may be most effective for cardiovascular health.

Determinants of Short- and Long-Term Outcomes of an Australian Cohort of Patients Admitted with Alcoholic Hepatitis

BACKGROUND AND AIMS

Alcoholic hepatitis is a common condition with high mortality. This study aimed to firstly describe the presentation, treatment, and short- and long-term outcomes of an Australian cohort of patients admitted to hospital with alcoholic hepatitis and secondly to validate existing prognostic models.

METHODS

This is a retrospective study of consecutive patients admitted with alcoholic hepatitis to a major academic liver center in Melbourne, Australia, between January 1, 2010, and December 31, 2019. Cases were identified through appropriate International Classification of Diseases version 10 coding as well as review of non-coded patients with compatible biochemistry. Baseline demographic data, alcohol consumption, laboratory values, treatment, and outcomes at 30 days, 90 days, and 12 months post-diagnosis were collected from electronic medical records. Mortality data were extracted from an independent state government death registry.

RESULTS

In total, 126 patients (72 males [57%], median age 51 years) were included in the final analysis. Ninety-five (75%) were cirrhotic at diagnosis, 81 (64%) met criteria for severe alcoholic hepatitis, and 41 (33%) had an infection during their index admission. 54% of eligible patients were treated with corticosteroids. 30-day and 12-month mortality rates were 8.7% and 27.1%, respectively, with hepatic encephalopathy (hazard ratio 5.45) and neutrophil-to-lymphocyte ratio (hazard ratio 1.09) independent markers for 12-month mortality on Cox regression analysis. Glasgow alcoholic hepatitis score outperformed other major prognostic models for short-term mortality.

CONCLUSIONS

The 12-month mortality rate of 27% following alcoholic hepatitis is lower than previously reported studies, with hepatic encephalopathy and neutrophil-to-lymphocyte ratio predictive of long-term outcome.

A Randomized, Double-blind, Placebo-controlled, Parallel Study Evaluating the Efficacy of Bacillus subtilis MB40 to Reduce Abdominal Discomfort, Gas, and Bloating

INTRODUCTION

Bloating is a common yet poorly managed complaint among healthy people, with a complex etiology that impacts health and general well-being. The study intended to evaluate the efficacy and safety of supplementation with a probiotic, Bacillus subtilis MB40 (MB40), on bloating, abdominal discomfort, and gas in healthy participants.

METHODS

In this multi-center, double-blind, placebo-controlled, parallel trial, 100 participants were randomized to receive either MB40 at 5 × 109 colony forming units (CFU; n = 50) or a placebo (n = 50) once daily for 4-weeks. Participants completed 3 questionnaires daily: a modified Abdominal Discomfort, Gas, and Bloating (mADGB) questionnaire, a modified Gastrointestinal Symptoms Rating Scale (mGSRS), and a Bowel Habits Diary (BHD). Participants' responses to each question were combined into weekly averages.

RESULTS

At the end of 4-weeks, there were no significant differences in average weekly change in daily bloating intensity, number of days with and duration of bloating, abdominal discomfort and gas between MB40 and placebo groups. However, the male sub-group on MB40 achieved clinical thresholds with a greater decrease over placebo in the intensity of (1.38) and number of days with (1.32) bloating, the number of days (1.06) and duration (86-minutes) of gas, the number of days with abdominal discomfort (1.32) and diarrhea symptom score (1.02). Role limitation (physical; P = .026), vitality (P = .034) and social functioning (P = .037) were significantly improved from baseline to week 4 in the MB40 group. At 2-weeks, physical functioning (P = .017) significantly improved in the MB40 group versus placebo.

CONCLUSIONS

Although MB40 supplementation did not significantly improve bloating across all populations, the male sub-group demonstrated clinically significant reductions in bloating intensity, number of days with abdominal discomfort, gas, bloating, and duration of gas, compared to placebo. Additionally, the male sub-group receiving MB40 had a 10% improvement in general health score. MB40 supplementation at a dose of 5 × 109 CFU daily for 4-weeks was also safe and well-tolerated as all biometric, vital, and hematological measures remained within normal laboratory ranges (Clinical Trials NCT02950012).

Activation of the kidney sodium chloride cotransporter by the β2-adrenergic receptor agonist salbutamol increases blood pressure

The thiazide-sensitive sodium-chloride-cotransporter (NCC) in the kidney distal convoluted tubule (DCT) plays an essential role in sodium and potassium homeostasis. Here, we demonstrate that NCC activity is increased by the β2-adrenoceptor agonist salbutamol, a drug prevalently used to treat asthma. Relative to β1-adrenergic receptors, the β2-adrenergic receptors were greatly enriched in mouse DCT cells. In mice, administration of salbutamol increased NCC phosphorylation (indicating increased activity) within 30 minutes but also caused hypokalemia, which also increases NCC phosphorylation. In ex vivo kidney slices and isolated tubules, salbutamol increased NCC phosphorylation in the pharmacologically relevant range of 0.01-10 μM, an effect observed after 15 minutes and maintained at 60 minutes. Inhibition of the inwardly rectifying potassium channel (Kir) 4.1 or the downstream with-no-lysine kinases (WNKs) and STE20/SPS1-related proline alanine-rich kinase (SPAK) pathway greatly attenuated, but did not prevent, salbutamol-induced NCC phosphorylation. Salbutamol increased cAMP in tubules, kidney slices and mpkDCT cells (model of DCT). Phosphoproteomics indicated that protein phosphatase 1 (PP1) was a key upstream regulator of salbutamol effects. A role for PP1 and the PP1 inhibitor 1 (I1) was confirmed in tubules using inhibitors of PP1 or kidney slices from I1 knockout mice. On normal and high salt diets, salbutamol infusion increased systolic blood pressure, but this increase was normalized by thiazide suggesting a role for NCC. Thus, β2-adrenergic receptor signaling modulates NCC activity via I1/PP1 and WNK-dependent pathways, and chronic salbutamol administration may be a risk factor for hypertension.

A215 MDR3 DEFICIENCY MIMICKING WILSON DISEASE

Background

The chronic phenotype of ALF includes a broad differential diagnosis. Class III multi-drug resistance P-glycoprotein 3 (MDR3) deficiency, also referred to as progressive familial intrahepatic cholestasis type 3, is an autosomal recessive genetic disorder. It is caused by a defect on the ABCB4 gene located on chromosome 7, which encodes MDR3. MDR3 is responsible for transporting phosphatidylcholine across the canalicular membrane, thereby allowing it to be incorporated into bile micelles. MDR3 deficiency results in increased levels of free bile acids and detergent bile. Progressive cholangiopathy ensues from this detergent bile and indirectly leads to cholestasis and liver failure in severe cases. Significantly increased urinary and hepatic copper (Cu), which are hallmarks of Wilson disease, have also been reported in patients with acute hepatitis and cholestasis including patients with MDR3 deficiency

Aims

We report a case of a girl who presented with a chronic phenotype of PALF, who had multiple features of Wilson disease and so was treated as such until genetic analysis confirmed MDR3 deficiency

Methods

Results

A 6 year old girl presented to the ED with a 1mth history of epistaxis and a 1wk history of abdominal pain and distension, facial edema, pallor and fever. Her family history was significant for parental consanguinity and maternal itch during pregnancy. On examination she had clubbing, scleral icterus and a distended abdomen with hepatosplenomegaly. Her bloodwork showed bicytopenia (HGB 53 & Plts 63) along with liver dysfunction (INR 2.9, albumin 25, conjugated bilirubin 9) and raised liver enzymes (transaminases & GGT &gt;10xULN). Her total serum bile acids were raised at 134. An US showed hepatosplenomegaly with multiple hyperechoic nodules and perisplenic varices. She was extensively worked up for malignancy, autoimmune and metabolic disease. Serum ceruloplasmin was reduced, ophthalmology examination showed no KF rings and her 24hr urinary Cu was 10xULN. Liver Cu quantification was markedly raised at 40xULN. Liver biopsy showed cirrhosis with fibrosis related minimal non-specific portal and septal inflammation. Additionally, complete loss of canalicular staining on immunohistochemistry for MDR3 protein was noted, suggestive of MDR3 deficiency. Based on the Cu levels, a provisional diagnosis of Wilson disease was made and Cu chelation therapy was commenced pending genetic testing. A cholestatic gene panel subsequently showed homozygous pathogenic variant for the ABCB4 gene. Trientine was stopped and she was commenced on ursodeoxycholic acid. Though biochemically she remains largely unchanged, she is clinically stable whilst awaiting a liver transplant

Conclusions

This case highlights the diagnostic difficulties associated with Cu test result interpretation in patients with chronic cholestatic liver disease and urges a thorough consideration of alternative diagnoses of PALF

Funding Agencies

None

Amoebic colitis: A case series of a recurring missed diagnosis

Entamoeba histolytica, a pathogenic protozoan that causes amoebiasis, remains the second leading cause of death from parasitic infections worldwide. We present a case series of patients presenting to metropolitan tertiary gastroenterology units in Melbourne, Australia, highlighting the complexities of diagnosing amoebic colitis and the potential for misdiagnosis. These cases illustrate four key lessons in the identification of amoebic colitis: (i) obtaining a thorough travel and exposure history, (ii) having a high index of suspicion, (iii) understanding the limitations of available investigations, and (iv) being aware that amoebic colitis may masquerade as other common conditions.

The Ability of Quercetin and Ferulic Acid to Lower Stored Fat is Dependent on the Metabolic Background of Human Adipocytes

SCOPE

Dietary flavonoids and phenolic acids can modulate lipid metabolism, but effects on mature human adipocytes are not well characterized.

MATERIALS AND METHODS

Human adipocytes are differentiated, and contain accumulated lipids, mimicking white adipocytes. They are then cultured either under conditions of actively synthesizing and accumulating additional lipids through lipogenesis ("ongoing lipogenic state") or under conditions of maintaining but not increasing stored lipids ("lipid storage state"). Total lipid, lipidomic and transcriptomics analyses are employed to assess changes after treatment with quercetin and/or ferulic acid.

RESULTS

In the "lipid storage state," a longer-term treatment (3 doses over 72 h) with low concentrations of quercetin and ferulic acid together significantly lowered stored lipid content, modified lipid composition, and modulated genes related to lipid metabolism with a strong implication of peroxisome proliferator-activated receptor (PPARα)/retinoid X receptor (RXRα) involvement. In the "ongoing lipogenic state," the effect of quercetin and ferulic acid is markedly different, with fewer changes in gene expression and lipid composition, and no detectable involvement of PPARα/RXRα, with a tenfold higher concentration required to attenuate stored lipid content.

CONCLUSIONS

Multiple low-dose treatment of quercetin and ferulic acid modulates lipid metabolism in adipocytes, but the effect is dramatically dependent on the metabolic state of the cell.

A110 DGAT1 MUTATION OF LIPID TRAFFICKING ASSOCIATED WITH A RARE CASE OF CONGENITAL DIARRHEA

Background

Congenital diarrheas and enteropathies (CODEs) are rare and cause severe chronic diarrhea in children under 2 years of age.1 Current genomic research has identified several monogenic defects resulting in epithelial disorders of nutrient and electrolyte transport, enzymes function, metabolism and trafficking.

Aims

To discuss a rare case of congential diarrhea.

Methods

Case Report.

Results

A 10-month-old Ashkenazi Jewish boy was referred to Pediatric Gastroenterology for loose stools and failure to thrive. Born at 27 weeks, he was a NICU inpatient for his first 3 months of life. Explosive loose stools were first noticed after discharge and treated as cow’s milk protein allergy. At aged 10 months he was admitted to his local hospital with irritability, abdominal distension, foul smelling loose stools and developmental delay. Despite an intake of 130kcal/kg/day he failed to gain weight (weight and length &lt; 3rd centile). His abdomen was distended but there was no organomegaly on examination.

On transfer to Sick Kids he underwent extensive work up with low albumin 24 g/L but normal CBC, amylase, lipase and IgA and

anti-TTG negative. The lipid profile showed hypertriglyceridemia 2.98 mmol/L (normal &lt;0.85), low HDL 0.81 mmol/L but normal total cholesterol. Low apoliprotein A1 0.79 g/L (0.92 - 1.96), low apoliprotein B 0.54 g (0.59 - 1.46) and vitamin E deficiency 9.6 umol/L (14.5 - 33.0). Normal fecal elastase (&gt; 500 ug/g stool). Upper GI endoscopy showed duodenal villi blunting with non-specific chronic inactive duodenitis on histopathology.

Due to ongoing poor weight gain he commenced TPN. A repeat endoscopy four weeks after admission revealed patchy villous blunting, crypt hyperplasia and enterocyte vacuolization. However, ultrastructural electron microscopy examination showed normal enterocyte brush border with well-formed microvilli with no inclusions or vesicular bodies. With a differential diagnosis of chylomicron retention disorder, abetalipoproteinemia or hypolipoproteinemia he was commenced on a low-fat diet with MCT feeds. A 72-hour fecal fat collection on this diet was within normal range 5.4 mmol/day (2–7).

One year later his weight is now on 3rd centile and his albumin levels have normalized. However, triglycerides remain elevated. Whole exome sequencing identified two pathogenic variants in the DGAT1 gene; c.629_631delCCT, pSer210del and c751 + 2T&gt;C, IVSB+2T&gt;C.

Conclusions

Diacylglycerol acyltransferase (DGAT)1 catalyzes triglyceride biosynthesis.2 Loss of function DGAT1 gene mutations are described in several cases studies3,4 characterized by electrolyte transport–related diarrhea, protein-losing enteropathy and growth failure. Our cases adds to the understanding of the phenotypic and histological spectrum of DGAT1 mutations. Management strategies currently focus on growth with dietary lipid restriction, while substituting fat-soluble vitamins and essential fatty acids.

Funding Agencies

CAG

National Criticality Experiments Research Center (NCERC) - capabilities and recent measurements

The National Criticality Experiments Research Center (NCERC) located at the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS) and operated by Los Alamos National Laboratory (LANL) is home to four critical assemblies which are used to support of range of missions, including nuclear criticality safety and nuclear nonproliferation. Additionally, subcritical systems can also be assembled at NCERC. NCERC is providing critical and subcritical experiments valuable to the nuclear data community and experiments performed at NCERC are often published as benchmarks in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook. This manuscript will give a broad overview of recent experiments performed at NCERC, upcoming experiments, and why integral measurements are important and useful to the nuclear data community.

The four critical assemblies are GODIVA IV, FLATTOP, COMET, and PLANET. GODIVA IV is a cylindrical metal fast burst reactor, the fourth in the GODIVA series that dates back to the 1950’s. FLATTOP is an highly enriched uranium (HEU) or Pu core reflected by natural uranium. COMET and PLANET are vertical lift assemblies, where one half of the reactor can be lifted to the upper half of the reactor to create a critical system. Some recent experiments include various critical intermediate energy assemblies with lead, and subcritical measurements of plutonium reflected by copper, tungsten, and nickel. Work is also underway to make a better measurement of the critical mass of neptunium, using a neptunium sphere surrounded by nickel shells. Additionally, measurements will be performed next year with HEU shells from Rocky Flats. These HEU shells will be stacked together to make larger systems, allowing for a large range of criticality (from subcritical to delayed critical). Other upcoming measurements include an HEU critical assembly sensitive to intermediate energy neutrons.

The Doctor Can See You Now: A Key Stakeholder Study Into The Acceptability Of Ambulance Based Telemedicine

Using telecommunications technology it would be possible to link a patient and paramedic to a Doctor in the Emergency Department (ED) at the point of first patient contact. A questionnaire-based study on telemedicine in the pre-hospital environment involving patients, paramedics, doctors and nurses in the ED, was performed to assess if they would want and accept telemedicine in pre-hospital emergency care. When asked 98.5% (55) of patients, 89% (11) of doctors, 76% (14) of nurses and 91% (42) of ambulance personnel saw the potential of an audio-visual link from the pre-hospital environment to the ED. The potential benefits were felt to be in diagnosis of time-dependent illnesses, time management, increased hospital preparedness for incoming patients and increased triage efficiency. Stakeholder enthusiasm for pre-hospital telemedicine must be met with the technological requirements to provide such a service. As noted by one patient a pre-hospital audio-visual link to the ED could be “potentially a life saving service”.

Acute inhibition of PMCA4, but not global ablation, reduces blood pressure and arterial contractility via a nNOS-dependent mechanism

Cardiovascular disease is the world's leading cause of morbidity and mortality, with high blood pressure (BP) contributing to increased severity and number of adverse outcomes. Plasma membrane calcium ATPase 4 (PMCA4) has been previously shown to modulate systemic BP. However, published data are conflicting, with both overexpression and inhibition of PMCA4 in vivo shown to increase arterial contractility. Hence, our objective was to determine the role of PMCA4 in the regulation of BP and to further understand how PMCA4 functionally regulates BP using a novel specific inhibitor to PMCA4, aurintricarboxylic acid (ATA). Our approach assessed conscious BP and contractility of resistance arteries from PMCA4 global knockout (PMCA4KO) mice compared to wild‐type animals. Global ablation of PMCA4 had no significant effect on BP, arterial structure or isolated arterial contractility. ATA treatment significantly reduced BP and arterial contractility in wild‐type mice but had no significant effect in PMCA4KO mice. The effect of ATAin vivo and ex vivo was abolished by the neuronal nitric oxide synthase (nNOS) inhibitor Vinyl‐l‐NIO. Thus, this highlights differences in the effects of PMCA4 ablation and acute inhibition on the vasculature. Importantly, for doses here used, we show the vascular effects of ATA to be specific for PMCA4 and that ATA may be a further experimental tool for elucidating the role of PMCA4.

Reduced expression of PMCA1 is associated with increased blood pressure with age which is preceded by remodelling of resistance arteries

Hypertension is a well‐established risk factor for adverse cardiovascular events, and older age is a risk factor for the development of hypertension. Genomewide association studies have linked ATP2B1, the gene for the plasma membrane calcium ATPase 1 (PMCA1), to blood pressure (BP) and hypertension. Here, we present the effects of reduction in the expression of PMCA1 on BP and small artery structure and function when combined with advancing age. Heterozygous PMCA1 null mice (PMCA1^Ht) were generated and conscious BP was measured at 6 to 18 months of age. Passive and active properties of isolated small mesenteric arteries were examined by pressure myography. PMCA1^Ht mice exhibited normal BP at 6 and 9 months of age but developed significantly elevated BP when compared to age‐matched wild‐type controls at ≥12 months of age. Decreased lumen diameter, increased wall thickness and increased wall:lumen ratio were observed in small mesenteric arteries from animals 9 months of age and older, indicative of eutrophic remodelling. Increases in mesenteric artery intrinsic tone and global intracellular calcium were evident in animals at both 6 and 18 months of age. Thus, decreased expression of PMCA1 is associated with increased BP when combined with advancing age. Changes in arterial structure precede the elevation of BP. Pathways involving PMCA1 may be a novel target for BP regulation in the elderly.

Selective inhibition of plasma membrane calcium ATPase 4 improves angiogenesis and vascular reperfusion

AIMS

Ischaemic cardiovascular disease is a major cause of morbidity and mortality worldwide. Despite promising results from pre-clinical animal models, VEGF-based strategies for therapeutic angiogenesis have yet to achieve successful reperfusion of ischaemic tissues in patients. Failure to restore efficient VEGF activity in the ischaemic organ remains a major problem in current pro-angiogenic therapeutic approaches. Plasma membrane calcium ATPase 4 (PMCA4) negatively regulates VEGF-activated angiogenesis via inhibition of the calcineurin/NFAT signalling pathway. PMCA4 activity is inhibited by the small molecule aurintricarboxylic acid (ATA). We hypothesize that inhibition of PMCA4 with ATA might enhance VEGF-induced angiogenesis.

METHODS AND RESULTS

We show that inhibition of PMCA4 with ATA in endothelial cells triggers a marked increase in VEGF-activated calcineurin/NFAT signalling that translates into a strong increase in endothelial cell motility and blood vessel formation. ATA enhances VEGF-induced calcineurin signalling by disrupting the interaction between PMCA4 and calcineurin at the endothelial-cell membrane. ATA concentrations at the nanomolar range, that efficiently inhibit PMCA4, had no deleterious effect on endothelial-cell viability or zebrafish embryonic development. However, high ATA concentrations at the micromolar level impaired endothelial cell viability and tubular morphogenesis, and were associated with toxicity in zebrafish embryos. In mice undergoing experimentally-induced hindlimb ischaemia, ATA treatment significantly increased the reperfusion of post-ischaemic limbs.

CONCLUSIONS

Our study provides evidence for the therapeutic potential of targeting PMCA4 to improve VEGF-based pro-angiogenic interventions. This goal will require the development of refined, highly selective versions of ATA, or the identification of novel PMCA4 inhibitors.

Developing a risk-based trading scheme for cattle in England: farmer perspectives on managing trading risk for bovine tuberculosis

This paper examines farmer attitudes towards the development of a voluntary risk-based trading scheme for cattle in England as a risk mitigation measure for bovine tuberculosis (bTB). The research reported here was commissioned to gather evidence on the type of scheme that would have a good chance of success in improving the information farmers receive about the bTB risk of cattle they buy. Telephone interviews were conducted with a stratified random sample of 203 cattle farmers in England, splitting the interviews equally between respondents in the high-risk area and low-risk area for bTB. Supplementary interviews and focus groups with farmers were also carried out across the risk areas. Results suggest a greater enthusiasm for a risk-based trading scheme in low-risk areas compared with high-risk areas and among members of breed societies and cattle health schemes. Third-party certification of herds by private vets or the Animal and Plant Health Agency were regarded as the most credible source, with farmer self-certification being favoured by sellers, but being regarded as least credible by buyers. Understanding farmers' attitudes towards voluntary risk-based trading is important to gauge likely uptake, understand preferences for information provision and to assist in monitoring, evaluating and refining the scheme once established.

Improved Delivery through Biological Membranes. Synthesis and Antiviral Activity of a Series of Ribavirin Chemical Delivery Systems: 2′ and 3′ Derivatives

Ribavirin was chemically manipulated to provide a number of derivatives in which a 1,4-dihydrotrigonellinate species was attached to either the 2′ or 3′-position. In addition, a variety of other modifications was used to augment the lipophilicity and stability of the ribavirin redox systems. Prepared compounds were tested in a murine model of viral encephalitis. Intravenous administration of an isomeric pair of derivatives (1-[3′-O-(N-methyl-3-carbonyl-1,4-dihydropyridine)-2′-O-benzoyl-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide/1-[2′-O-(N-methyl-3-carbonyl-1,4-dihydropyridine)-3′-O-benzoyl-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide) resulted in 43% survival compared with 0% for vehicle treatment and resulted in a decrease in brain viral titres by 10-fold.

Calcium Extrusion Pump PMCA4: A New Player in Renal Calcium Handling?

Calcium (Ca²⁺) is vital for multiple processes in the body, and maintenance of the electrolyte concentration is required for everyday physiological function. In the kidney, and more specifically, in the late distal convoluted tubule and connecting tubule, the fine-tuning of Ca²⁺ reabsorption from the pro-urine takes place. Here, Ca²⁺ enters the epithelial cell via the transient receptor potential vanilloid receptor type 5 (TRPV5) channel, diffuses to the basolateral side bound to calbindin-D_28k and is extruded to the blood compartment via the Na⁺/Ca²⁺ exchanger 1 (NCX1) and the plasma membrane Ca²⁺ ATPase (PMCA). Traditionally, PMCA1 was considered to be the primary Ca²⁺ pump in this process. However, in recent studies TRPV5-expressing tubules were shown to highly express PMCA4. Therefore, PMCA4 may have a predominant role in renal Ca²⁺ handling. This study aimed to elucidate the role of PMCA4 in Ca²⁺ homeostasis by characterizing the Ca²⁺ balance, and renal and duodenal Ca²⁺-related gene expression in PMCA4 knockout mice. The daily water intake of PMCA4 knockout mice was significantly lower compared to wild type littermates. There was no significant difference in serum Ca²⁺ level or urinary Ca²⁺ excretion between groups. In addition, renal and duodenal mRNA expression levels of Ca²⁺-related genes, including TRPV5, TRPV6, calbindin-D_28k, calbindin-D_9k, NCX1 and PMCA1 were similar in wild type and knockout mice. Serum FGF23 levels were significantly increased in PMCA4 knockout mice. In conclusion, PMCA4 has no discernible role in normal renal Ca²⁺ handling as no urinary Ca²⁺ wasting was observed. Further investigation of the exact role of PMCA4 in the distal convoluted tubule and connecting tubule is required.

Plasma membrane calcium ATPases (PMCAs) as potential targets for the treatment of essential hypertension

The incidence of hypertension, the major modifiable risk factor for cardiovascular disease, is increasing. Thus, there is a pressing need for the development of new and more effective strategies to prevent and treat hypertension. Development of these relies on a continued evolution of our understanding of the mechanisms which control blood pressure (BP). Resistance arteries are important in the regulation of total peripheral resistance and BP; changes in their structure and function are strongly associated with hypertension. Anti-hypertensives which both reduce BP and reverse changes in resistance arterial structure reduce cardiovascular risk more than therapies which reduce BP alone. Hence, identification of novel potential vascular targets which modify BP is important. Hypertension is a multifactorial disorder which may include a genetic component. Genome wide association studies have identified ATP2B1, encoding the calcium pump plasma membrane calcium ATPase 1 (PMCA1), as having a strong association with BP and hypertension. Knockdown or reduced PMCA1 expression in mice has confirmed a physiological role for PMCA1 in BP and resistance arterial regulation. Altered expression or inhibition of PMCA4 has also been shown to modulate these parameters. The mechanisms whereby PMCA1 and 4 can modulate vascular function remain to be fully elucidated but may involve regulation of intracellular calcium homeostasis and/or comprise a structural role. However, clear physiological links between PMCA and BP, coupled with experimental studies directly linking PMCA1 and 4 to changes in BP and arterial function, suggest that they may be important targets for the development of new pharmacological modulators of BP.

A peer outreach initiative to increase the registration of minorities as organ donors

Background

Black, Asian and minority ethnic (BAME) communities are disproportionately affected by inequalities in transplant services in the UK. There are some indications from pilot programmes that appeals for BAME organ donors may be more effectively communicated by employing grassroots, community-networking approaches, but such initiatives have not been adequately described or evaluated.

Methods

Lay individuals from BAME communities were trained as peer outreach workers. They attended a series of public events to promote knowledge of organ donation and transplantation among the public. Information was gathered from 806 evaluation forms completed by event attendees at 34 separate events. From these, 54 follow-up interviews were conducted with event attendees who completed evaluation forms, indicated that they intended to sign up to the NHS Organ Donor Register (ODR) within the next month and consented to follow-up.

Results

Peer outreach initiatives of the type evaluated are associated with increased numbers of BAME people registering as organ donors. A total of 8.8% of event attendees signed up to the NHS ODR. The programme was most effective with people who had previously considered becoming organ donors but who did not know how to go about it. It was less effective with people who had not previously considered it, or who were scared about signing up, or who feared family or religious disapproval.

Conclusions

Peer outreach programmes with BAME communities can be an effective way of reducing inequalities by increasing the number of people on the NHS ODR and encouraging people to think about the issue.

Mutual information as a measure of image quality for 3D dynamic lung imaging with EIT

We report on a pilot study of dynamic lung electrical impedance tomography (EIT) at the University of Manchester. Low-noise EIT data at 100 frames per second were obtained from healthy male subjects during controlled breathing, followed by magnetic resonance imaging (MRI) subsequently used for spatial validation of the EIT reconstruction. The torso surface in the MR image and electrode positions obtained using MRI fiducial markers informed the construction of a 3D finite element model extruded along the caudal-distal axis of the subject. Small changes in the boundary that occur during respiration were accounted for by incorporating the sensitivity with respect to boundary shape into a robust temporal difference reconstruction algorithm. EIT and MRI images were co-registered using the open source medical imaging software, 3D Slicer. A quantitative comparison of quality of different EIT reconstructions was achieved through calculation of the mutual information with a lung-segmented MR image. EIT reconstructions using a linear shape correction algorithm reduced boundary image artefacts, yielding better contrast of the lungs, and had 10% greater mutual information compared with a standard linear EIT reconstruction.

Dance as a Complex Intervention in an Acute Mental Health Setting: A Place ‘In-Between’

Introduction:

There is little research on dance in acute mental health settings in the National Health Service. This study evaluated a dance programme in an acute setting. Occupational therapists collaborated with a professional dancer to facilitate the programme.

Method:

The literature review revealed that studies on the benefits of dance tended to focus on clinical outcomes. This study adopted a mixed-method psychosocial approach. It used the Herth Hope Index with 11 service users. Fifteen interviews were conducted with service users. Five members of staff were interviewed and film-based data were also utilised. Interpretation panels were used to analyse and triangulate findings.

Findings:

The study found that the value of the dance programme was related to its ‘in-between’ status. Dance connected the inner and outer experience of service users by engaging the creative imagination and translating it into movement. It also contributed to a hopeful but realistic sense of connection between mind and body and to social groups inside and outside the hospital.

Conclusion:

Dance is a complex intervention, which provides an appropriate challenge for service users in acute mental health settings while contributing to a sense of biopsychosocial integration. As such, it has much to offer contemporary occupational therapy.