Hyponatremia timing, incidence, and associated risk factors in patients treated with cisplatin for lung cancer: a retrospective study.

The incidence of cisplatin-derived hyponatremia remains unknown, although nausea, vomiting, and renal dysfunction are common adverse events of cisplatin, a platinum-based preparation. The factor contributing to hyponatremia is described but not well known. This study aimed to retrospectively investigate the incidence of hyponatremia, timing, and associated risk factors. This study surveyed patients with lung cancer who received cisplatin chemotherapy from August 2013 to July 2019 at Shizuoka Cancer Center. The severity of hyponatremia was evaluated based on Common Terminology Criteria for Adverse Events. A total of 814 patients were included in this study. 682 (83.7%) patients had hyponatremia of any grade: grade 1 (<135-130 mmol/L), grade 3 (<130-120 mmol/L), and grade 4 (<120 mmol/L) hyponatremia were observed in 619 (76.0%), 51 (6.3%), and 12 (1.5%) patients, respectively. Of 63 patients with grade 3-4 hyponatremia, 43 (68.3%) developed it in the first treatment cycle. In multivariate analysis, the short hydration regimen (<3000 mL/day) has a lower incidence of grade 3-4 hyponatremia than a normal (>3000 mL) hydration regimen (OR: 0.35 [0.16-0.80], p = 0.013). In addition, if the Na+ value before the start of administration is < 135mmol/L, the incidence of grade3 and 4 hyponatremia is higher (OR:0.14 [0.07-0.28], p < 0.001). Hyponatremia due to cisplatin is likely to occur in patients with low Na levels before administration, such as the elderly. Since short hydration might avoid diuretics, hydration methods might need to be reconsidered to prevent hyponatremia.

Enhanced microbial biomass assay using mutant luciferase resistant to benzalkonium chloride.

In a biomass assay based on adenosine 5(')-triphosphate (ATP) bioluminescence, extracellular ATP is removed; then intracellular ATP is extracted from the microorganism by an ATP extractant and subsequently reacted with luciferase. To provide a highly sensitive assay, the concentration of benzalkonium chloride (BAC) in the ATP extractant was optimized by using a mutant luciferase resistant to BAC. The use of 0.2% BAC, which was acceptable for the luciferase, simultaneously achieved the maximum extraction of intracellular ATP from microorganisms and the inactivation of the ATP-eliminating enzymes for removal of extracellular ATP. The detection limit (blank+3 SD) for ATP was 1.8x10(-14)M (1.8x10(-18)mol/assay) in the presence of the ATP extractant with coefficients of variation of 0.7 to 6.3%. The reagent system coupled with the ATP-eliminating enzymes allowed for the detection of 93 colony-forming units (CFU)/ml of Escherichia coli ATCC 25922, 170CFU/ml of Pseudomonas aeruginosa ATCC 27853, 170CFU/ml of Proteus mirabilis ATCC 29906, 68CFU/ml of Staphylococcus aureus ATCC 25923, and 7.7CFU/ml of Bacillus subtilis ATCC 6051. The yeast cell of Saccharomyces cerevisiae IFO 10217 could be detected at 1CFU/ml. With 54 kinds of microorganisms, the average ATP extraction efficiency compared to the trichloroacetic acid extraction method was 81.0% in 24 strains among gram-negative bacteria, 99.4% in 13 strains among gram-positive bacteria, and 97.0% in 17 strains among yeast. The ATP contents of the gram-negative bacteria, gram-positive bacteria, and yeasts ranged from 0.40 to 2.70x10(-18)mol/CFU (mean=1.5x10(-18)mol/CFU), from 0.41 to 16.7x10(-18)mol/CFU (mean=5.5x10(-18)mol/CFU), and from 0.714 to 54.6x10(-16)mol/CFU (mean=8.00x10(-16)mol/CFU), respectively.

Enumeration of bacterial cell numbers by amplified firefly bioluminescence without cultivation.

We recently developed a novel bioluminescent enzymatic cycling assay for ATP and AMP with the concomitant use of firefly luciferase and pyruvate orthophosphate dikinase (PPDK), where AMP and pyrophosphate produced from ATP by firefly luciferase were converted back into ATP by PPDK. Background luminescence derived from contaminating ATP and AMP in the reagent was reduced using adenosine phosphate deaminase which degrades ATP, ADP, and AMP, resulting in constant and highly amplified bioluminescence with low background luminescence. To detect bacterial cells without cultivation, we applied the above bioluminescent enzymatic cycling reagent to rapid microbe detection system. ATP spots (0.31-5.0 amol/spot) at the level of a single bacterial cell were detected with 5 min signal integration, signifying that integrated luminescence was amplified 43 times in comparison to traditional ATP bioluminescence. Consequently, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Lactobacillus brevis in beer were detected without cultivation. Significant correlation was observed between the number of signal spots obtained using this novel system and the colony-forming units observed with the conventional colony-counting method (R(2)=0.973).