On-site production of a dialysis bath from dry salts. Results of solute concentration control by routine clinical chemistry.

BACKGROUND.: Dialysis bath production, at least in Europe, is currently based on pre-produced aqueous solutions of dialysis salts (concentrate), which are re-handled by dialysis machines to deliver the final dialysate concentrations. Because of the logistics of aqueous solution creation, a large amount of transportation capacity is needed. Therefore, we changed this process to use pre-produced dry salt containers and to undertake in-clinic dissolution of salts and concentration production. Because no preclinical control for solute concentrations is available so far using this new process, we employed routine clinical chemistry analytics. METHODS.: We report the controls of solute concentrations created by these methods for 746 samples of concentrates and 151 dissolution processes. For analysis, absolute and relative deviations from prescriptions and associations between the solute concentrations and the density controls of the concentrates were computed. RESULTS.: A total of 98% of all the concentrates were found to be within a 10% margin of error from the prescriptions. The mean relative deviation of the solute concentrations from the prescriptions was -0.635 ± 3.83%. Among particular solutes, sodium had the highest maximum deviation of 26 mmol/L from the prescription. Calcium and magnesium (small concentration solutes) exhibited small systematic errors of 1.37 and 1.22%, respectively. Other solute concentrations showed random errors only and no associations with the mean relative deviations of all the solutes within a production batch or with the density controls. CONCLUSIONS.: Single solute concentration control by routine clinical chemistry after dry salt production of concentrates is a valuable additional tool for monitoring clinical risk with dialysate concentrates. The analytical random error of clinical chemistry exceeds the weight tolerance of production; therefore, such analytics cannot be used for precision production and control of dry salt containers.

Minigenes encoding N-terminal domains of human cardiac myosin light chain-1 improve heart function of transgenic rats.

In this study we investigated whether the expression of N-terminal myosin light chain-1 (MLC-1) peptides could improve the intrinsic contractility of the whole heart. We generated transgenic rats (TGR) that overexpressed minigenes encoding the N-terminal 15 amino acids of human atrial MLC-1 (TGR/hALC-1/1-15, lines 7475 and 3966) or human ventricular MLC-1 (TGR/hVLC-1/1-15, lines 6113 and 6114) isoforms in cardiomyocytes. Synthetic N-terminal peptides revealed specific actin binding, with a significantly (P<0.01) lower dissociation constant (K(D)) for the hVLC-1/1-15-actin complex compared with the K(D) value of the hALC-1/1-15-actin complex. Using synthetic hVLC-1/1-15 as a TAT fusion peptide labeled with the fluorochrome TAMRA, we observed specific accumulation of the N-terminal MLC-1 peptide at the sarcomere predominantly within the actin-containing I-band, but also within the actin-myosin overlap zone (A-band) in intact adult cardiomyocytes. For the first time we show that the expression of N-terminal human MLC-1 peptides in TGR (range: 3-6 muM) correlated positively with significant (P<0.001) improvements of the intrinsic contractile state of the isolated perfused heart (Langendorff mode): systolic force generation, as well as the rates of both force generation and relaxation, rose in TGR lines that expressed the transgenic human MLC-1 peptide, but not in a TGR line with undetectable transgene expression levels. The positive inotropic effect of MLC-1 peptides occurred in the absence of a hypertrophic response. Thus, expression of N-terminal domains of MLC-1 represent a valuable tool for the treatment of the failing heart.

Monocyte-expressed urokinase regulates human vascular smooth muscle cell migration in a coculture model.

Interactions of vascular smooth muscle cells (VSMC) with monocytes recruited to the arterial wall at a site of injury, with resultant modulation of VSMC growth and migration, are central to the development of vascular intimal thickening. Urokinase-type plasminogen activator (uPA) expressed by monocytes is a potent chemotactic factor for VSMC and might serve for the acceleration of vascular remodeling. In this report, we demonstrate that coculture of human VSMC with freshly isolated peripheral blood-derived human monocytes results in significant VSMC migration that increases during the coculture period. Accordingly, VSMC adhesion was inhibited with similar kinetics. VSMC proliferation, however, was not affected and remained at the same basal level during the whole period of coculture. The increase of VSMC migration in coculture was equivalent to the uPA-induced migration of monocultured VSMC and was blocked by addition into coculture of soluble uPAR (suPAR). Analysis of uPA and uPAR expression in cocultured cells demonstrated that monocytes are a major source of uPA, whose expression increases in coculture five-fold, whereas VSMC display an increased expression of cell surface-associated uPAR. These findings indicate that upregulated uPA production by monocytes following vascular injury acts most likely as an endogenous activator of VSMC migration contributing to the remodeling of vessel walls.