Is salt sensitivity of blood pressure linked to the cardiometabolic syndrome?

Validation of low-cost mobile phone applications and comparison with professional imaging systems for three-dimensional facial imaging: A pilot study

PURPOSE

The objective of this study was to investigate the accuracies of three-dimensional (3D) facial scanning mobile phone applications as compared to professional 3D facial imaging systems.

MATERIALS AND METHODS

A manikin head model was used as the subject for comparing six 3D facial imaging systems which comprised three professional 3D scanners (3dMDface, Artec Eva and Vectra H2) and three mobile phone applications (Bellus3D, ScandyPro and Hedges). For each system, five scans were taken to analyse (1) linear accuracy using 9 measurements (2) global and (3) regional 3D accuracy of the scanned surface by root mean square (RMS) and colour map analysis. Another set of five scans was repeated by a second operator to evaluate the inter-operator reproducibility for each system.

RESULTS

All the facial imaging systems had absolute errors lesser than 1.0 mm for the linear measurements. The technical error of measurement (TEM) for inter-examiner and intra-examiner linear measurements were within acceptable limits. Artec Eva, Vectra H2 and Scandy Pro had poor global 3D trueness (RMS > 1.0 mm) but good 3D regional trueness (RMS < 1.0 mm). 3dMDface, Bellus3D Face App and Heges had good global and regional 3D trueness. All the facial imaging systems had good global and regional 3D precision and reproducibility (RMS < 1.0 mm).

CONCLUSION

This study demonstrated that mobile phone 3D scanning applications had comparable trueness, precision and reproducibility to professional systems. Colour map analysis supplemented the use of the RMS value to demonstrate facial regions of significant deviation. Clinicians should also consider the specific area or region of inaccuracies for each system to determine whether the chosen system is appropriate for the clinical condition or procedure.

CLINICAL SIGNIFICANCE

Mobile phone 3D facial imaging applications may be as accurate as 3D professional facial scanning systems for craniomaxillofacial purposes. However, the choice of the system may vary depending on the specific area of interest.

Sodium bicarbonate cotransporter NBCe2 gene variants increase sodium and bicarbonate transport in human renal proximal tubule cells

RATIONALE

Salt sensitivity of blood pressure affects >30% of the hypertensive and >15% of the normotensive population. Variants of the electrogenic sodium bicarbonate cotransporter NBCe2 gene, SLC4A5, are associated with increased blood pressure in several ethnic groups. SLC4A5 variants are also highly associated with salt sensitivity, independent of hypertension. However, little is known about how NBCe2 contributes to salt sensitivity, although NBCe2 regulates renal tubular sodium bicarbonate transport. We hypothesized that SLC4A5 rs10177833 and rs7571842 increase NBCe2 expression and human renal proximal tubule cell (hRPTC) sodium transport and may be a cause of salt sensitivity of blood pressure.

OBJECTIVE

To characterize the hRPTC ion transport of wild-type (WT) and homozygous variants (HV) of SLC4A5.

METHODS AND RESULTS

The expressions of NBCe2 mRNA and protein were not different between hRPTCs carrying WT or HV SLC4A5 before or after dopaminergic or angiotensin (II and III) stimulation. However, luminal to basolateral sodium transport, NHE3 protein, and Cl-/HCO3- exchanger activity in hRPTCs were higher in HV than WT SLC4A5. Increasing intracellular sodium enhanced the apical location of NBCe2 in HV hRPTCs (4.24±0.35% to 11.06±1.72% (P<0.05, N = 3, 2-way ANOVA, Holm-Sidak test)) as determined by Total Internal Reflection Fluorescence Microscopy (TIRFM). In hRPTCs isolated from kidney tissue, increasing intracellular sodium enhanced bicarbonate-dependent pH recovery rate and increased NBCe2 mRNA and protein expressions to a greater extent in HV than WT SLC4A5 (+38.00±6.23% vs HV normal salt (P<0.01, N = 4, 2-way ANOVA, Holm-Sidak test)). In hRPTCs isolated from freshly voided urine, bicarbonate-dependent pH recovery was also faster in those from salt-sensitive and carriers of HV SLC4A5 than from salt-resistant and carriers of WT SLC4A5. The faster NBCe2-specific bicarbonate-dependent pH recovery rate in HV SCL4A5 was normalized by SLC4A5- but not SLC4A4-shRNA. The binding of purified hepatocyte nuclear factor type 4A (HNF4A) to DNA was increased in hRPTCs carrying HV SLC4A5 rs7571842 but not rs10177833. The faster NBCe2-specific bicarbonate-dependent pH recovery rate in HV SCL4A5 was abolished by HNF4A antagonists.

CONCLUSION

NBCe2 activity is stimulated by an increase in intracellular sodium and is hyper-responsive in hRPTCs carrying HV SLC4A5 rs7571842 through an aberrant HNF4A-mediated mechanism.

Dietary sodium and health: more than just blood pressure

Sodium is essential for cellular homeostasis and physiological function. Excess dietary sodium has been linked to elevations in blood pressure (BP). Salt sensitivity of BP varies widely, but certain subgroups tend to be more salt sensitive. The mechanisms underlying sodium-induced increases in BP are not completely understood but may involve alterations in renal function, fluid volume, fluid-regulatory hormones, the vasculature, cardiac function, and the autonomic nervous system. Recent pre-clinical and clinical data support that even in the absence of an increase in BP, excess dietary sodium can adversely affect target organs, including the blood vessels, heart, kidneys, and brain. In this review, the investigators review these issues and the epidemiological research relating dietary sodium to BP and cardiovascular health outcomes, addressing recent controversies. They also provide information and strategies for reducing dietary sodium.

Office and ambulatory blood pressure-lowering effects of combination valsartan/hydrochlorothiazide vs. hydrochlorothiazide-based therapy in obese, hypertensive patients

The authors evaluated the blood pressure (BP)-lowering effects of combination valsartan/hydrochlorothiazide (HCTZ) vs. amlodipine/HCTZ in a 16-week, double-blind, randomized, forced-titration study and ambulatory BP monitoring (ABPM) substudy involving centrally obese hypertensive patients 40 years and older. Patients were started on valsartan/HCTZ 160/12.5 mg or HCTZ 12.5 mg monotherapy, force-titrated at week 4 to valsartan/HCTZ 320/25 mg and HCTZ 25 mg, respectively. The HCTZ group initiated amlodipine 5 mg at week 8 and 10 mg at week 12. A subset of patients had 24-hour ABPM at baseline and weeks 8 and 16. At week 16 in the intent-to-treat population (n=401), valsartan/HCTZ and amlodipine/HCTZ lowered office systolic BP (-30.6 vs. -28.3 mm Hg; P=.14). In the ABPM subgroup (n=111), valsartan/HCTZ was more effective than amlodipine/HCTZ in reducing 24-hour systolic BP (-20.6 vs. -14.5 mm Hg; P=.011). In obese hypertensive patients, valsartan/HCTZ reduced office BP similar to amlodipine/HCTZ but lowered 24-hour systolic BP more.

Blood pressure AsSAuLTed by the circadian clock

While Cry proteins are necessary for circadian rhythmicity, they now appear to play a seminal role in blood pressure regulation. In a recent issue of Nature Medicine, Doi et al., 2009 show how the circadian clock may use Cry proteins to protect from salt-sensitive hypertension.