Metolazone vs chlorothiazide in acute heart failure patients with diuretic resistance and renal dysfunction: a retrospective cohort study.

Guidelines recommend intravenous (IV) loop diuretics as first-line therapy for patients hospitalized with acute heart failure (AHF) and volume overload. Additional agents can be utilized for augmentation but there is limited guidance on agent selection. The study objective was to determine if chlorothiazide or metolazone is associated with differences in diuretic efficacy or safety in loop diuretic-resistant patients with AHF and renal dysfunction. We conducted a multi-center, retrospective cohort study of patients hospitalized with AHF and renal dysfunction who received metolazone or chlorothiazide in addition to IV loop diuretics. The primary endpoint was a comparison of 24-hour urine output (UOP) between the 24 hours before and after thiazide administration. Secondary and safety endpoints included weight change, requirement for vasopressors or inotropes, electrolyte abnormalities, and changes in renal function. A total of 223 patients were included. The mean daily diuretic doses were chlorothiazide 632 mg and metolazone 7 mg. Mean 24-hour UOP increased more among chlorothiazide- (1668 to 3826 mL) versus metolazone-treated patients (1672 to 2834 mL) (p<0.001) after addition of the second diuretic. No statistically significant differences in weight or serum creatinine changes were observed. More hypomagnesemia was observed in the chlorothiazide group; no differences in other electrolytes or serum creatinine were observed. Chlorothiazide was associated with a greater increase in 24-hour UOP than metolazone without an excess of potassium or serum creatinine derangements. However, weight changes did not differ significantly between groups. Future prospective studies are needed to confirm potential differences in diuretic response and safety.

Regulation of fibroblast Fas expression by soluble and mechanical pro-fibrotic stimuli.

BACKGROUND: Fibroblast apoptosis is a critical component of normal repair and the acquisition of an apoptosis-resistant phenotype contributes to the pathogenesis of fibrotic repair. Fibroblasts from fibrotic lungs of humans and mice demonstrate resistance to apoptosis induced by Fas-ligand and prior studies have shown that susceptibility to apoptosis is enhanced when Fas (CD95) expression is increased in these cells. Moreover, prior work shows that Fas expression in fibrotic lung fibroblasts is reduced by epigenetic silencing of the Fas promoter. However, the mechanisms by which microenvironmental stimuli such as TGF-ß1 and substrate stiffness affect fibroblast Fas expression are not well understood. METHODS: Primary normal human lung fibroblasts (IMR-90) were cultured on tissue culture plastic or on polyacrylamide hydrogels with Young's moduli to recapitulate the compliance of normal (400 Pa) or fibrotic (6400 Pa) lung tissue and treated with or without TGF-ß1 (10 ng/mL) in the presence or absence of protein kinase inhibitors and/or inflammatory cytokines. Expression of Fas was assessed by quantitative real time RT-PCR, ELISA and Western blotting. Soluble Fas (sFas) was measured in conditioned media by ELISA. Apoptosis was assessed using the Cell Death Detection Kit and by Western blotting for cleaved PARP. RESULTS: Fas expression and susceptibility to apoptosis was diminished in fibroblasts cultured on 6400 Pa substrates compared to 400 Pa substrates. TGF-ß1 reduced Fas mRNA and protein in a time- and dose-dependent manner dependent on focal adhesion kinase (FAK). Surprisingly, TGF-ß1 did not significantly alter cell-surface Fas expression, but did stimulate secretion of sFas. Finally, enhanced Fas expression and increased susceptibility to apoptosis was induced by combined treatment with TNF-α/IFN-γ and was not inhibited by TGF-ß1. CONCLUSIONS: Soluble and matrix-mediated pro-fibrotic stimuli promote fibroblast resistance to apoptosis by decreasing Fas transcription while stimulating soluble Fas secretion. These findings suggest that distinct mechanisms regulating Fas expression in fibroblasts may serve different functions in the complex temporal and spatial evolution of normal and fibrotic wound-repair responses.

Evaluating Risk Factors for Developing Hypoglycemia During Treatment of Hyperkalemia With Intravenous Regular Insulin.

Background: The conventional dose of 10 units of intravenous (IV) regular insulin to treat hyperkalemia has been associated with hypoglycemia. There have been retrospective studies evaluating weight-based dose vs conventional dose of IV regular insulin but the comparative efficacy and safety is not well established. Objective: Evaluate the difference in weight-based dosing of IV regular insulin between patients who experienced hypoglycemia vs. patients who did not experience hypoglycemia after the administration of IV regular insulin. Methods: This was a retrospective, electronic chart review at a single academic medical center which included patients ≥18 years of age with an emergency department or inpatient encounter who were administered IV regular insulin within 6 hours of a pre-treatment potassium of ≥5 mmol/L. Results: There was no significant difference in the weight-based insulin dose between patients who experienced a hypoglycemic event and patients who did not experience a hypoglycemic event (.14 vs .22 units/kg; P = .44). The potassium-lowering effect was similar between the two groups (1.02 vs .96 mmol/L; P = .56). A regression analysis revealed that female sex, low baseline blood glucose (glucose <140 mg/dL), and those who received a repeat dose of IV regular insulin were independent risk factors for development of hypoglycemia. Conclusion: This study found no difference in hypoglycemic events and potassium lowering based on IV weight-based regular insulin dosing, however other risk factors may predict hypoglycemia.