This study was performed to evaluate the efficacy of various treatment modalities for hyperkalemia in 8 end-stage renal disease (ESRD) patients. Simultaneous administration of sodium bicarbonate and insulin with glucose was compared with infusion of either bicarbonate alone or insulin and glucose. Plasma potassium was measured at the baseline and after 60 min of infusion with each regimen. Infusion of 8.4% solution of sodium bicarbonate at 2 mEq/ min for 60 min induced a significant rise in blood bicarbonate from 21.7 ± 2.1 to 26.3 ± 1.7 mEq/l (p < 0.01), but failed to lower plasma potassium (6.4 ± 0.1 vs. 6.3 ± 0.2 mEq/l, before and after). Intravenous infusion of insulin and glucose (5 mU/kg/min for 60 min) significantly lowered plasma potassium from 6.3 ± 0.1 to 5.7 ± 0.1 mEq/l (p < 0.01). The combined infusion of bicarbonate and insulin with glucose showed the greatest decline in plasma potassium, from 6.2 ± 0.2 to 5.2 ± 0.1 mEq/l (p < 0.01). With the combined regimen, the increases in plasma bicarbonate (22.3 ± 1.7 to 25.8 ± 1.9 mEq/l, p < 0.05) and blood pH (7.36 ± 0.02 to7.42 ± 0.02, p < 0.01) were significant, but somewhat less than those with bicarbonate administration alone. Plasma insulin levels before treatment were similar in all treatment regimens, and increased markedly following the infusion of insulin with glucose, either with or without sodium bicarbonate (9 ± 1.5 vs. 10 ± 10 μU/ml before insulin, and 196 ± 18.0 vs. 201 ± 26.4 μU/ml after insulin). Plasma epinephrine, norepinephrine, osmolality and plasma aldosterone before and after treatment did not show any significant differences among the 3 different regimens. In conclusion, the ineffectiveness of sodium bicarbonate alone and its synergistic effect with insulin and glucose in acute therapy of hyperkalemia in ESRD patients suggest that mild metabolic acidosis, which is common in patients on maintenance hemodialysis, may contribute to tissue insensitivity to the action of insulin on transcellular potassium shift.

The foremost step in the initial clinical management of hyperkalemia is to decide whether a hyperkalemic patient requires immediate treatment to avoid a life-threatening situation (serum potassium concentration >6.0 mEq/l and EKG changes). When the decision for urgent treatment of hyperkalemia is based on EKG changes, an important caveat for clinicians is that absent or atypical EKG changes do not exclude the necessity for immediate intervention. Once an urgent situation has being handled with intravenous push of a 10% calcium salt, the initiation of short-term measures can be launched by either a single or combined regimen of the three agents that cause a transcellular shift of potassium – insulin with glucose, β₂-agonist (albuterol), and NaHCO₃. As the first choice among these available options, we favor an intravenous bolus of 10 units of insulin with 50 ml of 50% glucose alone or in combination with 10–20 mg of albuterol by nebulizer. These can be repeated as required until the institution of hemodialysis. The combination of insulin with glucose and NaHCO₃ as an another option needs further clarification for its additive effects. However, NaHCO₃ has lost its favor because of its poor efficacy as a potassium-lowering agent when used alone. The next step is to remove potassium from the body – diuretics (furosemide), cation exchange resin (kayexelate) with sorbitol, and dialysis (preferably hemodialysis). The final important step for the managements of hyperkalemia is a long-term plan to prevent its recurrence or worsening. In addition to every effort to elucidate underlying causes and pathophysiologic mechanisms for hyperkalemia, an extensive search must be made to uncover overt or sometimes covert medications that may have led to the development of hyperkalemia. Furthermore, one must obtain detailed dietary and medical history of hyperkalemic patients.

Nodules are formed on legume roots as a result of signaling between symbiotic partners and in response to the activities of numerous genes. We cloned fragments of differentially expressed genes in spot-inoculated soybean (Glycine max) roots. Many of the induced clones were similar to known genes related to oxidative stress, such as thioredoxin and b-carotene hydroxylase. The deduced amino acid sequences of full-length soybean cDNAs for thioredoxin and b-carotene hydroxylase were similar to those in other species. In situ RNA hybridization revealed that the thioredoxin gene is expressed on the pericycle of 2-d-old nodules and in the infected cells of mature nodules, suggesting that thioredoxin is involved in nodule development. The thioredoxin promoter was found to contain a sequence resembling an antioxidant responsive element. When a thioredoxin mutant of yeast was transformed with the soybean thioredoxin gene it became hydrogen peroxide tolerant. These observations prompted us to measure reactive oxygen species levels. These were decreased by 3-to 5-fold in 7-d-old and 27-d-old nodules, coincident with increases in the expression of thioredoxin and b-carotene hydroxylase genes. Hydrogen peroxide-producing regions identified with cerium chloride were found in uninoculated roots and 2-d-old nodules, but not in 7-d-old and 27-d-old nodules. RNA interference-mediated repression of the thioredoxin gene severely impaired nodule development. These data indicate that antioxidants such as thioredoxin are essential to lower reactive oxygen species levels during nodule development.

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This study aimed to assess the effects of different dialysate bicarbonate concentrations in correcting acid-base imbalance in 53 stable hemodialysis patients in a university-hemodialysis unit. Three different bicarbonate concentrations were assigned, i.e. 25 mEq/L in 10, 30 mEq/L in 30, and 35 mEq/L in 13 patients. Blood gas analyses from arterial line blood samples before and after dialysis in the mid-week were performed for the determination of pH and serum bicarbonate (HCO3-) concentration. The mean values of predialysis arterial HCO3- were mildly acidotic in all 3 groups, but not significantly different among them, whereas those of post-dialysis arterial HCO3- were alkalotic, especially in the group of 35 mEq/L as compared with the other two groups. The mean blood pH was not significantly different among the 3 groups. As expected, there was a positive correlation between pre-dialysis pH and post-dialysis pH (r=0.45, p=0.001), and pre-dialysis HCO3- and post-dialysis HCO3- (r=0.58, p=0.000), but with a negative correlation between pre-dialysis HCO3- and the increment of intradialytic HCO3- following hemodialysis (r=-0.46, p=0.001). In conclusion, this study shows that the impact of conventional dialysate bicarbonate concentrations ranging from 25 to 35 mEq/L is not quite different on the mild degree of predialysis acidemia, but the degree of postdialysis alkalemia is more prominent in higher bicarbonate concentrations. Base supply by hemodialysis alone does not seem to be the main factor to determine the predialysis acidosis in end-stage renal disease patients on chronic maintenance hemodialysis.

Time-series sediment traps were deployed on the Chukchi Sea and East Siberian Sea slopes from August 2017 to August 2018 with the aim of elucidating the temporal and spatial variations in particle fluxes and identifying the main processes affecting those variations. Particle fluxes showed a typical seasonal pattern, with high values in summer and low values in other seasons, and a large inter-annual variation was observed only on the East Siberian Sea slope, where particle fluxes were one order of magnitude higher in early August 2018 than in late August 2017. This large inter-annual variation in particle flux resulted from the episodic intrusion of nutrient-enriched shelf water in the East Siberian Sea, which enhanced biological production at the surface and particle fluxes. The Chukchi Sea slope was influenced by the inflow of Anadyr Water, with high salinity and high nutrient concentrations, which had little annual variability. Therefore, particle flux showed little inter-annual variation on the Chukchi Sea slope. Under-ice phytoplankton blooms were observed in both the Chukchi Sea and East Siberian Sea slopes, and increases in particulate organic carbon (POC) flux and the C:N ratio under the sea ice were related to transparent exopolymer (TEP) production by ice algae. On the East Siberian Sea slope, particle fluxes increased slightly from 115 to 335 m, indicating lateral transport of suspended particulate matter; POC and lithogenic particles may be laterally transported to the slope as nutrient-rich shelf waters flowed from the East Siberian Sea to the Makarov Basin. Annual POC fluxes were 2.3 and 2.0 g C m–2 year–1 at 115 and 335 m, respectively, on the East Siberian Sea slope and was 2.1 g C m–2 year–1 at 325 m on the Chukchi Sea slope. Annual POC fluxes were higher on the Chukchi Sea and East Siberian Sea slopes than in Arctic basins, lower than on Arctic shelves, and generally similar to those on western Arctic slopes.