Immunolocalisation of sodium/proton exchanger-like proteins in the gills of elasmobranchs

Na⁺/H⁺ exchangers are integral membrane proteins that exchange Na⁺ and H⁺ across cell membranes. The Na⁺/H⁺ exchangers 2 and 3 are epithelial isoforms in mammals and contribute to acid–base homeostasis. The gills of fishes, including elasmobranchs, are also associated with acid/base balance, and are probably the primary acid/base regulatory organ. This study examines the presence of Na⁺/H⁺ exchangers 2 and 3 using immunohistochemistry and immunoblotting in the gills of four species of elasmobranchs, the banjo ray (Trygonorrhina fasciata), southern eagle ray (Myliobatis australis), the gummy shark (Mustelus antarcticus) and the Australian angel shark (Squatina australis) using heterologous antibodies. Na⁺/H⁺ exchanger 2-like immunoreactivity was observed in the gills of the banjo ray, eagle ray and angel shark. In the banjo and eagle rays, this Na⁺/H⁺ exchanger-like immunoreactivity co-localised with immunoreactivity to Na⁺/K⁺-ATPase, a marker for the mitochondrial-rich cells of fishes. Na⁺/H⁺ exchanger 3-like immunoreactivity was only observed in the gills of the angel and gummy sharks, some Na⁺/H⁺ exchanger 3-like cells also showed Na⁺/K⁺-ATPase immunoreactivity. However, immunoblotting of banjo and eagle ray gill membranes demonstrated Na⁺/H⁺ exchanger 3-like immunoreactivity, which was not consistent with the immunohistochemical results. These data demonstrate the presence of epithelial Na⁺/H⁺ exchangers 2 and 3 in the gills of elasmobranchs and a link with acid/base regulation is suggested.

Determination of sodium oxalate in Bayer liquor using flow-analysis incorporating an anion exchange column and tris(2,2`-bipyridyl)ruthenium(II) chemiluminescence detection

Semi-automated flow injection instrumentation, incorporating a small anion exchange column coupled with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy)₃²⁺) chemiluminescence detection, was configured and utilised to develop rapid methodology for the determination of sodium oxalate in Bayer liquors. The elimination of both negative and positive interferences from aluminium(III) and, as yet, unknown concomitant organic species, respectively are discussed. The robustness of the methodology was considerably enhanced by using the temporally stable form of the chemiluminescence reagent, tris(2,2′-bipyridyl)ruthenium(III) perchlorate in dry acetonitrile. Real Bayer process samples were analysed and the results obtained compared well with those performed using standard methods within industrial laboratories.

New insights into the structures of diorganotellurium Oxides. The first polymeric diorganotelluroxane[(p-MeOC6H4)2TEO]n

The characterization of the previously reported diorganotellurium oxides R₂TeO (R = Ph (1) and p-MeOC₆H₄ (2)) was revisited by osmometric molecular weight determinations, ¹²⁵Te NMR spectroscopy, and electrospray spectrometry (ESMS) in solution and by 125Te MAS NMR spectroscopy in the solid state. The single-crystal X-ray structure of 2 revealed a polymeric arrangement that features a zigzag configured Te-O backbone without any secondary Te···O interactions. In solution 1 and 2 exist predominantly as monomers but appear to be in equilibrium with higher oligomers to a minor extent.

Decreasing dietary sodium while following a self-selected potassium-rich diet reduces blood pressure

Reducing dietary sodium reduces blood pressure (BP), a major risk factor for cardiovascular disease, but few studies have specifically examined the effect on BP of altering dietary sodium in the context of a high potassium diet. This randomized, crossover study compared BP values in volunteer subjects self-selecting food intake and consuming low levels of sodium (Na+; 50 mmol/d) with those consuming high levels of sodium (> or =20 mmol/d), in the context of a diet rich in potassium (K+). Sodium supplementation (NaSp) produced the difference in Na+ intake. Subjects (n = 108; 64 women, 44 men; 16 on antihypertensive therapy) had a mean age of 47.0 ± 10.1 y. Subjects were given dietary advice to achieve a low sodium (LS) diet with high potassium intake (50 mmol Na+/d, >80 mmol K+/d) and were allocated to NaSp (120 mmol Na+/d) or placebo treatment for 4 wk before crossover. The LS diet decreased urinary Na+ from baseline, 138.7 ± 5.3 mmol/d to 57.8 ± 3.8 mmol/d (P < 0.001). The NaSp treatment returned urinary Na+ to baseline levels 142.4 ± 3.7 mmol/d. Urinary K+ increased from baseline, 78.6 ± 2.3 to 86.6 ± 2.1 mmol/d with the LS diet and to 87.1 ± 2.1 mmol/d with NaSp treatment (P < 0.001). The LS diet reduced home systolic blood pressure (SBP) by 2.5 ± 0.8 mm Hg (P = 0.004), compared with the NaSp treatment. Hence, reducing Na+ intake from 140 to 60 mmol/d significantly decreased home SBP in subjects dwelling in a community setting who consumed a self-selected K+-rich diet, and this dietary modification could assist in lowering blood pressure in the general population.

New light from an old reagent: chemiluminescence from the reaction of potassium permanganate with sodium borohydride

When aqueous sodium borohydride (50 mM) is added to a solution of potassium permanganate (1mM, in sodium hexametaphosphate) at acidic pH, bright red-orange emission is easily visible in a darkened room. This chemiluminescence emission is due to an excited state of manganese (II) that undergoes solution phase phosphorescence and provides an excellent opportunity for students to explore the relationship between the initial oxidation state of the manganese and the likelihood of luminescence. Not surprisingly Mn(VII), Mn(IV) and Mn(III) all give rise to chemiluminescence where as Mn(II) fails to react.

Synthesis and structure of bis(para-methoxyphenyl)selenoxide and its monohydrate. theoretical considerations of the hydration of diorganoselenium oxides

The title compound was prepared by base hydrolysis of (p-MeOC₆H₄)₂SeCl₂ in water and isolated as the crystalline monohydrate, (p-MeOC₆H₄)₂SeO·H₂O, in which the water molecule is associated via hydrogen-bonding. Water-free (p-MeOC₆H₄)₂SeO was obtained crystalline after drying and recrystallisation from toluene. Both crystal phases were investigated by single crystal X-ray diffraction. Preliminary DFT calculations at the B3LYP/LANL2DZdp level of theory suggest that the hydrogen bonded complexes R₂SeO·H₂O (R = H, Me, Ph) are by 2.79, 3.36 and 11.10 kcal mol^-1 more stable than the corresponding elusive diorganoselenium dihydroxides R₂Se(OH)₂. The hydrogen bond energies of R₂SeO·H₂O (R = H, Me, Ph) are 5.98, 7.18 and 5.89 kcal mol^-1.

Understanding ring strain and ring flexibility in six - and eight-membered cyclic organometallic group 14 oxides

A simple model was developed for the approximation of ring strain energies of homo- and heterometallic, six- and eight-membered cyclic organometallic group 14 oxides and the degree of puckering of their ring conformations. The conformational energy of a ring is modelled as the sum of its angular strain components. The bending potential energy functions for the various endocyclic M–O–M′ and O–M–O linkages (M, M′=Si, Ge, Sn) were calculated at the B3LYP/(v)TZ level of theory using H3MOM′H3 and H2M(OH)2 as model compounds. For the six-membered rings, the minimum total angular contribution to ring strain, ERSGmin was calculated to decrease in the order: cyclo-(H2SiO)3 (13.0 kJ mol−1)>cyclo-H2Sn(OSiH2)2O (7.0 kJ mol−1)>cyclo-H2Ge(OSiH2)2O (4.9 kJ mol−1)>cyclo-H2Si(OSnH2)2O (3.4 kJ mol−1)>cyclo-(H2SnO)3 (1.7 kJ mol−1)>cyclo-H2Si(OGeH2)2O (0.8 kJ mol−1)≈cyclo-H2Ge(OSnH2)2O (0.7 kJ mol−1)>cyclo-H2Sn(OGeH2)2O (0.1 kJ mol−1)≈cyclo-(H2GeO)3 (0 kJ mol−1). All of the six-membered rings were predicted to adopt (nearly) planar conformations (a=0.996<a<1). By contrast, all eight-membered rings were predicted to adopt strainless, but puckered conformations. The degree of puckering was predicted to increase in the order: cyclo-(H2SiO)4 (a=0.983)<cyclo-H2Sn(OSiH2O)2SiH2 (a=0.959)<cyclo-(H2SiO)2(H2SnO)2 (a=0.942)< cyclo-H2Si(OSnH2O)2SiH2 (a=0.935)<cyclo-(H2SnO)4 (a=0.916)<cyclo-(H2GeO)4 (a=0.885). The differences in ring strain and the degree of puckering were linked to the different electronegativities of Si, Ge and Sn. The results obtained are consistent with experimental ring strain energies; reactivities towards ring opening polymerizations or ring expansion reactions and observed ring conformations of cyclic organometallic group 14 oxides.

The influence of sodium salts on binary mixtures of bitter-tasting compounds

In order to study potential mixture interactions among bitter compounds, selected sodium salts were added to five compounds presented either alone or as binary bitter- ompound mixtures. Each compound was tested at a concentration that elicited ‘weak’ perceived bitterness. The bitter compounds were mixed at these concentrations to form a subset of possible binary mixtures. For comparison, the concentration of each solitary compound was doubled to measure bitterness inhibition at the higher intensity level elicited by the mixtures. The following sodium salts were tested for bitterness inhibition: 100 mM sodium chloride (salty), 100 mM sodium gluconate (salty), 100 and 20 mM monosodium glutamate (umami), and 50 mM adenosine monophosphate disodium salt (umami). Sucrose (sweet) was also employed as a bitterness suppressor. The sodium salts differentially suppressed the bitterness of compounds and their binary combinations. Although most bitter compounds were suppressed, the bitterness of tetralone was not suppressed, nor was the bitterness of the binary mixtures that contained it. In general, the percent suppression of binary mixtures of compounds was predicted by the average percent suppression of its two components. Within the constraints of the present study, the bitterness of mixtures was suppressed by sodium salts and sucrose independently, with few bitter interactions. This is consistent with observations that the bitter taste system integrates the bitterness of multi-compound solutions linearly.

Suppression of bitterness using sodium salts

Bitterness is an ongoing taste problem for both the pharmaceutical and food industries. This paper reports on how salts (NaCI, NaAcetate, NaGluconate, LiCI, KCI) and bitter compounds (urea, quinine-HCI, caffeine, amiloride-HCI, magnesium sulfate, KCI) interact to influence bitter perception. Sodium salts differentially suppress bitterness of these compounds; for example urea bitterness was suppressed by over 70% by sodium salts, while MgSO4 bitterness was not reduced. This study indicated that lithium ions had the same bitter suppressing ability as sodium ions, however the potassium cation had no bitter suppression ability. Changing the anion attached to the sodium did not affect bitter suppression, however, as the anion increased in size, perceived saltiness decreased. This indicates that sodium's mode of action is at the peripheral taste level, rather than a cognitive affect. A second experiment revealed that suppressing bitterness with a sodium salt in a bitter/sweet mixture causes an increase in sweetness. This suggests adding salt to a food matrix will not only increase salt perception, but also potentiate flavor by differential suppression of undesirable tastes such as bitter, while increasing more desirable tastes such as sweet.

Sodium adsorption using activated alumina for application in the dairy industry

Basic activated alumina with negatively charged surface is considered as a potential adsorbent for a targeted molecule with positive polarity. Adsorption of sodium by basic activated alumina was investigated as a method for desalting dairy waste streams, in which sodium ion concentration averaged 600 mg/L. Sodium equilibrium and kinetic adsorption were investigated using basic activated alumina with synthetic brines. The results of equilibrium adsorption show that uptake of sodium by activated alumina is significantly higher when the pH is greater than 8 and increases as the pH of the brines increases until pH reaches around 10. The results of kinetic adsorption show that 90 hours were needed to reach equilibrium for sodium adsorption. Binding and diffusion processes are suggested to have taken place within the activated alumina.

Gender differences in adherence to sodium-restricted diet patients with heart failure.

Background

Despite the importance of the sodium-restricted diet (SRD) to heart failure (HF) management, patient adherence is poor. Little is known about gender differences in adherence or factors that affect patients' ability to follow SRD recommendations. The purposes of this study were to determine whether there were gender differences in (1) adherence to the SRD; (2) knowledge about SRD and HF self-care; and (3) perceived barriers to following the SRD.
Methods and Results

Forty-one men and 27 women completed the Heart Failure Attitudes and Barriers questionnaire that measured HF self-care, knowledge, and perceived barriers to follow an SRD. Diet adherence was measured by 24-hour urinary sodium excretion (UNa). Women were more adherent to the SRD than men as reflected by 24-hour urine excretion (2713 versus 3859 mg UNa, P = .01). Women recognized signs of excess sodium intake such as fluid buildup (P = .001) and edema (P = .01) more often than men and had better understanding of appropriate actions to take related to following an SRD. There were no gender differences in perceived barriers to follow an SRD.
Conclusions

Although men and women perceived similar barriers, women were more adherent to the SRD and had greater knowledge about following an SRD. Further investigation of this phenomenon is warranted to determine if better adherence contributes to improved outcomes in women.

Effect of sodium bicarbonate on muscle metabolism during intense endurance cycling

Introduction: Sodium bicarbonate (NaHCO₃) ingestion has been shown to increase both muscle glycogenolysis and glycolysis during brief submaximal exercise. These changes may be detrimental to performance during more prolonged, exhaustive exercise. This study examined the effect of NaHCO₃ ingestion on muscle metabolism and performance during intense endurance exercise of ~60 min in seven endurance-trained men. Methods: Subjects ingested 0.3 g·kg^-1 body mass of either NaHCO₃ or CaCO₃ (CON) 2 h before performing 30 min of cycling exercise at 77 ± 1% [latin capital V with dot above]O_2peak followed by completion of 469 ± 21 kJ as quickly as possible (~30 min, ~80% [latin capital V with dot above]O_2peak). Results: Immediately before, and throughout exercise, arterialized-venous plasma HCO₃- concentrations were higher (P < 0.05) whereas plasma and muscle H⁺ concentrations were lower (P < 0.05) in NaHCO₃ compared with CON. Blood lactate concentrations were higher (P < 0.05) during exercise in NaHCO₃, but there was no difference between trials in muscle glycogen utilization or muscle lactate content during exercise. Reductions in PCr and ATP and increases in muscle Cr during exercise were also unaffected by NaHCO₃ ingestion. Accordingly, exercise performance time was not different between treatments. Conclusion: NaHCO₃ ingestion resulted in a small muscle alkalosis but had no effect on muscle metabolism or intense endurance exercise performance in well-trained men.