Stable potassium isotopes (41K/39K) track transcellular and paracellular potassium transport in biological systems

As the most abundant cation in archaeal, bacterial, and eukaryotic cells, potassium (K⁺) is an essential element for life. While much is known about the machinery of transcellular and paracellular K transport–channels, pumps, co-transporters, and tight-junction proteins—many quantitative aspects of K homeostasis in biological systems remain poorly constrained. Here we present measurements of the stable isotope ratios of potassium (⁴¹K/³⁹K) in three biological systems (algae, fish, and mammals). When considered in the context of our current understanding of plausible mechanisms of K isotope fractionation and K⁺ transport in these biological systems, our results provide evidence that the fractionation of K isotopes depends on transport pathway and transmembrane transport machinery. Specifically, we find that passive transport of K⁺ down its electrochemical potential through channels and pores in tight-junctions at favors ³⁹K, a result which we attribute to a kinetic isotope effect associated with dehydration and/or size selectivity at the channel/pore entrance. In contrast, we find that transport of K⁺ against its electrochemical gradient via pumps and co-transporters is associated with less/no isotopic fractionation, a result that we attribute to small equilibrium isotope effects that are expressed in pumps/co-transporters due to their slower turnover rate and the relatively long residence time of K⁺ in the ion pocket. These results indicate that stable K isotopes may be able to provide quantitative constraints on transporter-specific K⁺ fluxes (e.g., the fraction of K efflux from a tissue by channels vs. co-transporters) and how these fluxes change in different physiological states. In addition, precise determination of K isotope effects associated with K⁺ transport via channels, pumps, and co-transporters may provide unique constraints on the mechanisms of K transport that could be tested with steered molecular dynamic simulations.

Oral Health Inequalities among Indigenous and Non-Indigenous Children

INTRODUCTION

Our ability to address child oral health inequalities would be greatly facilitated by a more nuanced understanding of whether underlying disease experience or treatment opportunities account for a larger share of differences between social groups. This is particularly relevant in the context of population subgroups who are socially marginalized, such as Australia's Indigenous population. The decayed, missing, and filled (dmf) surfaces index is at once a reflection of dental caries experience (d) and its management (m and f).

OBJECTIVES

To 1) describe socioeconomic inequalities in dental caries experience and its management among Indigenous and non-Indigenous children and 2) compare these inequalities using absolute and relative measures.

METHODS

Data were from the Australian National Child Oral Health Study 2012-2014. Absolute and relative income inequalities were assessed for overall dmfs and its individual components (ds, ms, fs) using adjusted means and health disparity indices (Slope Index of Inequality [SII] and Relative Index of Inequality [RII]).

RESULTS

Mean dmfs among Indigenous children aged 5 to 10 y was 6.4 (95% confidence interval [CI], 5.4-7.4), ranging from 2.3 in the highest to 9.1 in the lowest income group. Mean dmfs among non-Indigenous children was 2.9 (95% CI, 2.8-3.1), ranging from 1.9 in the highest to 4.2 in the lowest income group. Age- and gender-adjusted social gradients for Indigenous children were evident across all dmfs components but were particularly notable for ds (SII = -4.6, RII = -1.7) and fs (SII = -3.2, RII = -1.5). The social gradients for non-Indigenous children were much lower in magnitude: ds (SII = -1.8, RII = -1.6) and fs (SII = -0.7, RII = -0.5).

CONCLUSION

Our findings suggest that socioeconomic disadvantage may translate into both higher disease experience and increased use of dental services for both Indigenous and non-Indigenous groups, with the social gradients being much more amplified among Indigenous children.

KNOWLEDGE TRANSFER STATEMENT

The findings of this study demonstrate the magnitude of disparities in dental caries among children by population groups in Australia. Our results suggest that the relationship between socioeconomic disadvantage and poor oral health is more deleterious among Indigenous than non-Indigenous children. Tackling upstream determinants of health might not only affect population patterns of health and disease but also mitigate the overwhelming racial inequalities in oral health between Indigenous and non-Indigenous Australians.

Electrolyte and transporter responses to angiotensin II induced hypertension in female and male rats and mice

AIM

Sexual dimorphisms are evident along the nephron: Females (F) exhibit higher ratios of renal distal to proximal Na⁺ transporters' abundance, greater lithium clearance (C_Li ) more rapid natriuresis in response to saline infusion and lower plasma [K⁺ ] vs. males (M). During angiotensin II infusion hypertension (AngII-HTN) M exhibit distal Na⁺ transporter activation, lower proximal and medullary loop transporters, blunted natriuresis in response to saline load, and reduced plasma [K⁺ ]. This study aimed to determine whether responses of F to AngII-HTN mimicked those in M or were impacted by sexual dimorphisms evident at baseline.

METHODS

Sprague Dawley rats and C57BL/6 mice were AngII infused via osmotic minipumps 2 and 3 weeks, respectively, and assessed by metabolic cage collections, tail-cuff sphygmomanometer, semi-quantitative immunoblotting of kidney and patch-clamp electrophysiology.

RESULTS

In F rats, AngII-infusion increased BP to 190 mm Hg, increased phosphorylation of cortical NKCC2, NCC and cleavage of ENaC two to threefold, increased ENaC channel activity threefold and aldosterone 10-fold. K⁺ excretion increased and plasma [K⁺ ] decreased. Evidence of natriuresis in F included increased urine Na⁺ excretion and C_Li , and decreased medullary NHE3, NKCC2 and Na,K-ATPase abundance. In C57BL/6 mice, AngII-HTN increased abundance of distal Na⁺ transporters, suppressed proximal-medullary transporters and reduced plasma [K⁺ ] in both F and M.

CONCLUSION

Despite baseline sexual dimorphisms, AngII-HTN provokes similar increases in BP, aldosterone, distal transporters, ENaC channel activation and K⁺ loss accompanied by similar suppression of proximal and loop Na⁺ transporters, natriuresis and diuresis in females and males.

Galectin isolated from parasite inhibits remission of experimental autoimmune encephalomyelitis by up-regulating autoantibody

Recently, parasite infections or parasite-derived products have been suggested as a therapeutic strategy with suppression of immunopathology, which involves the induction of regulatory T cells or/and T helper type 2 (Th2) responses. In a recent study, researchers reported that constructed recombinant galectin (rTl-gal) isolated from an adult worm of the gastrointestinal nematode parasite Toxascaris leonina attenuated clinical symptoms of inflammatory bowel disease in mice treated with dextran sulphate sodium. Noting the role of rTl-gal in inflammatory disease, we attempted to investigate the effect of the parasite via its rTl-gal on neuronal autoimmune disease using experimental autoimmune encephalomyelitis (EAE), a mouse inflammatory and demyelinating autoimmune disease model of human multiple sclerosis. In this model, rTl-gal-treated experimental autoimmune encephalomyelitis (EAE) mice failed to recover after the peak of the disease, leading to persistent central nervous system (CNS) damage, such as demyelination, gliosis and axonal damage. Further, rTl-gal-treated EAE mice markedly increased the number of CD45R/B220(+) B cells in both infiltrated inflammation and the periphery, along with the increased production of autoantibody [anti-myelin oligodendrocyte glycoprotein (MOG)35-55 ] in serum at chronic stage. Upon antigen restimulation, rTl-gal treatment affected the release of overall cytokines, especially interferon (IFN)-γ and tumour necrosis factor (TNF)-α. Our results suggest that galectin isolated from a gastrointestinal parasite can deliver a harmful effect to EAE contrary to its beneficial effect on inflammatory bowel disease.

Greater inequalities in dental treatment than in disease experience

This study aimed to (1) describe social gradients in dental caries in a population-level survey and (2) examine whether inequalities are greater in disease experience or in its treatment. Using data from Australia's National Survey of Adult Oral Health 2004-2006, we examined absolute and relative income inequalities for DMFT and its separate components (DT, MT, FT) using adjusted proportions, means, and health disparity indices [Slope Index of Inequality (SII) and Relative Index of Inequality (RII)]. Approximately 90% of Australian adults had experienced caries, with prevalence ranging from 89.7% in the highest to 96.6% in the lowest income group. Social gradients in caries were evident across all components of DMFT, but particularly notable in Missing (SII = -15.5, RII = -0.3) and untreated Decay (SII = -23.7, RII = -0.9). Analysis of age- and gender-adjusted data indicated less variation in levels of disease experienced (DMFT) than in the health outcomes of its management (missing teeth). The findings indicate that social gradients for dental caries have a greater effect on how the disease was treated than on lifetime disease experience.

Neuraxial anesthesia for cardiac surgery: thoracic epidural and high spinal anesthesia - why is it different?

Anesthesiologists can offer much more then stable blood pressure and heart rate in the intraoperative period. By choosing appropriate anesthetic techniques they can tremendously influence perioperative stress. This may positively impact on the overall surgical outcome. One of the most intriguing aspects of neuraxial anesthesia is its ability to attenuate the stress response to surgery. At present there is no agreement on the clinical importance of such a response but there is substantial indirect evidence that it may play an important role in a patient's outcome. Neuraxial anesthesia supplemented by general anesthesia is justified and can be safely used in cardiac surgery. The authors of this expert opinion prefer spinal anesthesia to thoracic epidural anesthesia and have been using it routinely for the last 20 years without any neurological complications. The risk of spinal hematoma from a 27G spinal needle prior to full heparinization is unknown but in our opinion is remote. Both epidural and spinal techniques can and should have a place in modern cardiac anesthesia practice and should be further investigated.

Evaluation of wheelchair sling seat and sling back crashworthiness

Many wheelchairs are used as vehicle seats by those who cannot transfer to a vehicle seat. Although ANSI/RESNA WC-19 has been recently adopted as a standard to evaluate crashworthiness of the wheelchairs used as motor vehicle seats, replacement or after-market seats may not be tested to this standard. This study evaluated the crashworthiness of two specimens each of three unique sling backs and three unique sling seats using a static test procedure intended to simulate crash loading conditions. To pass the test, a sling back is required to withstand a 2290 lb load, and a sling seat should be capable of withstanding a 3750 lb load. All, but two sling back specimens which failed at 1567 lb and 1787 lb, withstood the test criterion load. Two of six tested sling seats failed to pass the test: one failed at 3123 lb and the other failed to sustain the load for 5 s although it reached the test criterion load. Most of the failures occurred at the seams of the side openings of upholsteries where the wheelchair frame inserts for attachment.

Wheelchairs used as motor vehicle seats: seat loading in frontal impact sled testing

Wheelchairs are not typically designed to function as motor vehicle seats. However, many wheelchair users are unable to transfer to a vehicle seat and instead travel seated in their wheelchair. ANSI/RESNA WC19: Wheelchairs Used as Seats in Motor Vehicles provides design and testing requirements, but does not provide wheelchair manufacturers with design guidance related to expected loads imposed upon wheelchair components during a crash. To provide manufacturers with crashworthy design guidance, our study measured wheelchair seat loading during 20g/48kph frontal impact sled tests with a 50th percentile male test dummy. Loading conditions were assessed using two different rear securement point positions. Results of four sled impact tests revealed downward loads ranging from 17 019 to 18 682 N, depending upon rear securement point configuration. Maximum fore/aft shear loads ranged from 4424 to 6717 N across the tests.

Wheelchair integrated occupant restraints: feasibility in frontal impact

Individuals often use their wheelchair as a motor vehicle seat when traveling in motor vehicles. The current use of fixed vehicle-mounted wheelchair occupant restraint systems (FWORSs) often results in poor belt fit and discomfort. Additionally, satisfaction, usability and usage rate of FWORSs during transit use are often low. The automotive industry has shown improved occupant restraint usage, belt fit and injury protection when integrating the upper torso and pelvic restraint in a motor vehicle seat. This study compared occupant injury measures of a FWORS to a concept wheelchair integrated restraint system (WIRS) using a 20g frontal sled impact test with a 30 mph change in velocity. Neck loads, neck moments, head, pelvis and chest acceleration, sternum compression and knee and head excursion data were recorded from the wheelchair seated 50th percentile male hybrid III anthropomorphic test dummy (ATD). The WIRS resulted in a lower head injury criteria (HIC) value, lower sternum compression and a lower upper-torso restraint load than the FWORS. Compared with the FWORS, increased head, knee and wheelchair excursions and higher neck loads and moments were measured in the WIRS test. Both restraint scenario injury parameters were complied with occupant injury criteria based on General Motors Injury Assessment Reference Values (GM-IARVs) and occupant kinematic requirements defined by the Society of Automotive Engineers (SAE) voluntary standard, J2249. A higher motion criteria index was calculated for the WIRS scenario and a comparable combined injury criteria index was calculated for both restraint scenarios. The sled impact test showed WIRS concept feasibility, facilitating further development by industrial manufacturers who might further want to pursue this restraint principle to increase wheelchair occupant safety and comfort during transport in motor vehicles.

Evaluation of wheelchair drop seat crashworthiness

Wheelchair seating crash performance is critical to protecting wheelchair users who remain seated in their wheelchairs during transportation. Relying upon computer simulation and sled testing seat loads associated with a 20 g/48 kph (20 g/30 mph) frontal impact and 50th percentile male occupant were estimated to develop test criteria. Using a static test setup we evaluated the performance of various types of commercially available drop seats against the loading test criteria. Five different types of drop seats (two specimens each) constructed of various materials (i.e. plastics, plywood, metal) were evaluated. Two types of drop seats (three of the total 10 specimens) met the 16650 N (3750 lb) frontal impact test criteria. While additional validation of the test protocol is necessary, this study suggests that some drop seat designs may be incapable of withstanding crash level loads.

Evaluation of wheelchair seating system crashworthiness: "drop hook"-type seat attachment hardware

OBJECTIVE

To evaluate the crashworthiness of commercially available hardware that attaches seat surfaces to the wheelchair frame.

DESIGN

A low cost static crashworthiness test procedure that simulates a frontal impact motor vehicle crash.

SETTING

Safety testing laboratory.

SPECIMENS

Eleven unique sets of drop-hook hardware made of carbon steel (4), stainless steel (4), and aluminum (3).

INTERVENTIONS

Replicated seat-loading conditions associated with a 20g/48 kph frontal impact. Test criterion for seat loading was 16,680 N (3750 lb).

MAIN OUTCOME MEASURES

Failure load and deflection of seat surface.

RESULTS

None of the hardware sets tested met the crashworthiness test criterion. All failed at less than 50% of the load that seating hardware could be exposed to in a 20g/48 kph frontal impact. The primary failure mode was excessive deformation, leading to an unstable seat support surface.

CONCLUSIONS

Results suggest that commercially available seating drop hooks may be unable to withstand loading associated with a frontal crash and may not be the best option for use with transport wheelchairs.

Configurational analysis of chiral acids as O-trifluoroacetylated (-)-menthyl esters by achiral dual-capillary column gas chromatography

The simultaneous enantiomeric separation of 30 racemic acids including 24 hydroxy acids in a single analysis is described for the determination of their absolute configurations. It involves the conversion of each enantiomer into diastereomeric O-trifluoroacetylated (-)-menthyl ester for the direct separation by gas chromatography on achiral dual-capillary columns of different polarities, with subsequent identification and chiral discrimination by retention index (I) library matching. Among the acids studied, the enantiomers of 27 acids were discriminatively resolved on both non-polar DB-5 and the intermediate-polar DB-17 columns with resolution factors in the range of 0.7-7.7 and separation factors in the range of 1.002-1.021. Enantiomers of 3-hydroxybutyric and alpha-methoxyphenylacetic acids were partially resolved on DB-5 (resolution factor of 0.9), but not resolved on DB-17, while the baseline resolution for 3-hydroxydecanoic acid and the minimal separation on the peak top (resolution factor less than 0.7) for 2-hydroxyglutaric acid were achieved on DB-17 but not on DB-5. The temperature-programmed I values measured on both columns were characteristic of each enantiomer and thus simple I matching with the reference values was useful in cross-checking for their chemical identification and the chiral discrimination as well. When applied to a clinical urine sample, the present method allowed positive identification of endogenous (S)-lactic acid and (S)-2-hydroxybutyric acid along with (R)-3-hydroxybutyric acid.

Cs(2)CO(3)-promoted efficient carbonate and carbamate synthesis on solid phase

[reaction: see text] Mild and efficient preparation of alkyl carbonates and carbamates on solid supports is described herein. Alcohols or amines were coupled with Merrifield's resin through a CO(2) linker in the presence of cesium carbonate and tetrabutylammonium iodide (TBAI).

Evaluation of wheelchair back support crashworthiness: combination wheelchair back support surfaces and attachment hardware

Automotive seats are tested for compliance with federal motor vehicle safety standards (FMVSS) to assure safety during impact. Many wheelchair users rely upon their wheelchairs to serve as vehicle seats. However, the crashworthiness of these wheelchairs during impact is often unknown. This study evaluated the crashworthiness of five combinations of wheelchair back support surfaces and attachment hardware using a static test procedure simulating crash loading conditions. The crashworthiness was tested by applying a simulated rearward load to each seat-back system. The magnitude of the applied load was established through computer simulation and biodynamic calculations. None of the five tested wheelchair back supports withstood the simulated crash loads. All failures were associated with attachment hardware.

Enantiomeric separation and discrimination of 2-hydroxy acids as O-trifluoroacetylated (S)-(+)-3-methyl-2-butyl esters by achiral dual-capillary column gas chromatography

An efficient method is described for the simultaneous enantiomeric separation of 18 different racemic 2-hydroxy acids for the determination of their absolute configurations. It involves the conversion of each enantiomer into a diastereomeric O-trifluoroacetylated (S)-(+)-3-methyl-2-butyl ester for the direct separation by achiral dual-capillary column gas chromatography with subsequent identification and determination of its chirality by retention index (I) library matching. The enantiomers of each acid were well separated with high resolution values (R > or = 1.4) on DB-5 and DB-17 columns of different polarity. When temperature-programmed I values of 2-hydroxy acid enantiomers as their diastereomeric derivatives were measured on both columns, the I values were characteristic of each enantiomer. Simple I matching with the reference values was thus useful in cross-checking each acid enantiomer for the identification and chiral discrimination. When applied to urine samples, the present method allowed positive identification of most of the spiked 2-hydroxy acids from normal urine and for endogenous (S)-lactic acid and (S)-2-hydroxybutyric acid from a clinical urine specimen.

[Relationship between genotype of angiotensin converting enzyme gene and left ventricular hypertrophy in Chinese hypertensives]

OBJECTIVE

To search into the relationship between genotype of angiotensin-converting enzyme (ACE) gene and left ventricular hypertrophy(LVH) in Chinese hypertensives.

METHODS

ACE genotyping with polymerase chain reaction (PCR) was performed in 33 unrelated hypertensives with LVH, 55 hypertensives without cardio-cerebrovascular diseases and 62 healthy controls.

RESULTS

The frequencies of DD genotype (0.394) and deletion allele (0.606) among hypertensives with LVH were significantly higher than those (0.129 and 0.387) among controls and those (0.128 and 0.400) among hypertensives without cardio-cerebrovascular diseases.

CONCLUSION

A deletion polymorphism of ACE gene probably increases the risk for left ventricular hypertrophy in Chinese hypertensives.

Junctional epidermolysis bullosa with pyloric atresia: A case with favourable outcome

BACKGROUND

Pyloric atresia is a rare but serious condition that can occur with junctional epidermolysis bullosa (PA-JEB). Early recognition is necessary for timely intervention, but prognosis can be serious and mortality is high.

OBJECTIVE

We describe the case of a patient with PA-JEB who not only survived past infancy, but showed improvement in cutaneous blistering as she grew older.

CONCLUSION

With early surgical intervention, some patients with PA-JEB can survive and look forward to a favourable prognosis, with improvement of cutaneous blistering by early childhood.

[The relationship between angiotensin-converting enzyme gene polymorphism and brain infarction in Chinese hypertensives]

OBJECTIVE

To identify the insertion/deletion(I/D) polymorphism of angiotensin-converting enzyme(ACE) gene in Chinese hypertensives complicated with brain infarction.

METHODS

ACE genotyping with polymerase chain reaction(PCR) was performed in 62 unrelated healthy controls, 55 hypertensives without cardio-cerebrovascular diseases and 44 hypertensives complicated with brain infarction (all controls had no hypertension family history, while the cases had hypertension family history).

RESULTS

No significant differences could be detected between ACE gene I/D polymorphism and hypertension. However,the frequencies of DD genotype and deletion allele among hypertensives complicated with brain infarction (29.6% vs 56.8%) were higher than those among healthy controls (12.9% vs 38.7%, P<0.05 and P<0.01) and those among hypertensive without cardio-cerebrovascular diseases(12. 8% vs 40%, P<0.05 and P<0.02).

CONCLUSION

A deletion polymorphism of ACE gene is probably an important hereditary factor of brain infarction's morbidity in Chinese hypertensives. The detection of ACE genotypes in hypertensives would improve the early diagnosis of brain infarction.

Cholinergic innervation of cerebral cortex in organotypic slice cultures: sustained basal forebrain and transient striatal cholinergic projections

Slices of entire forebrain hemispheres were taken from early postnatal rat pups and maintained as organotypic slice cultures. Basal forebrain cholinergic neurons, identified by histochemical staining for acetylcholinesterase, develop axons that grow rapidly into cerebral cortex. Ingrowth occurs by two routes: some axons course laterally from the basal forebrain region to reach lateral neocortex; others course dorsally from the septum to reach medial cortex. By one to two weeks in vitro, acetylcholinesterase-positive axons have extended throughout most of the cortical territory. In addition to basal forebrain cholinergic axons, the normally local circuit cholinergic neurons of the striatum also send axons into cerebral cortex. These striatum-derived axons can be distinguished from basal forebrain axons by their distinct morphological characteristics and by their different response to excision of the striatum or basal forebrain. Further, acetylcholinesterase-positive axons in cortex that originate from striatum appear to retract or degenerate after about one week in culture, while those from basal forebrain remain present and apparently healthy beyond two weeks. These data document the basal forebrain cholinergic ingrowth into cerebral cortex using this whole hemisphere slice culture system and also demonstrate different degrees of maintenance of cortical afferents that are derived from different subcortical sources.

Separation of nucleosides and nucleotides by reversed-phase high-performance liquid chromatography with volatile buffers allowing sample recovery

Reversed-phase high-performance liquid chromatography using a C18 column with volatile buffers as the eluant was applied to the separation of a number of nucleosides and nucleotides. Groups of seven nucleosides and five nucleoside monophosphates were separated isocratically employing 0.1 M trimethylammonium acetate and 2% acetonitrile at pH 7.0. Groups of seven nucleoside diphosphates and seven nucleoside triphosphates were separated with 0.1 M triethylammonium bicarbonate and 2% acetonitrile titrated to a pH of 7.1 with acetic acid. The techniques described give resolution and separations comparable to nonvolatile buffers. Moreover, the eluant trimethylammonium acetate or triethylammonium bicarbonate buffer can easily be removed in vacuo from the column effluent, making the technique useful for preparative separations of these compounds. The observed elution pattern of nucleoside phosphates suggests that "paired-ion" chromatography is involved in the separation.