Cytoprotection by omega-3 fatty acids as a therapeutic drug vehicle when combined with nephrotoxic drugs in an intravenous emulsion: Effects on intraglomerular mesangial cells

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Distinct concentrations of Ketorolac/Gentamicin are toxic to mesangial (MES 13) cells.

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Omega-3 fatty acids protect intraglomerular mesangial cells against nephrotoxic drugs.

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Omega-6 fatty acids do not protect MES 13 cells against nephrotoxic drugs.

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Cytoprotection by n-3 PUFA may be due to increased intracellular redox state.

During therapeutic interventions, blood concentrations of intravenously applied drugs are higher, and their onset of pharmacological action is faster than with other routes of drug administration. However, acute drug therapy often produces nephrotoxic side effects, as commonly seen after treatment with Ketorolac or Gentamicin leading to questions about their use, especially for patients at risk for acute renal failure. Omega-6(n-6) and omega-3(n-3) polyunsaturated fatty acids (PUFA) affect eicosanoid metabolism, which plays a role in the regulation of inflammation. Eicosanoids derived from n-6 FA have proinflammatory and immunoactive functions, whereas eicosanoids derived from n-3 PUFA have anti-inflammatory and cytoprotective properties. We hypothesized that providing such injectable drugs with nephrotoxic potential in combination with n3-PUFAs from the outset, might afford rapid cytoprotection of renal cells, given the recent evidence that intravenously administered n3-PUFAs are rapidly incorporated into cell membranes. We used intraglomerular mesangial cells (MES13) that are sensitive to treatment with Ketorolac or Gentamicin instead of proximal tubular cells which do not respond to Ketorolac. We found a significant inhibition of Ketorolac (0.25, 0.5, 1 mM) or Gentamicin (2.5, 5 mM) induced cytotoxicity after pretreatment of MES13 cells with 0.01% of 20%w/v LipOmega-3 Emulsion 9/1, containing 90:10 wt/wt mixture of fish oil derived triglycerides to medium chain triglycerides.

Evaluation of implementation of a fully automated algorithm (enhanced model predictive control) in an interacting infusion pump system for establishment of tight glycemic control in medical intensive care unit patients

BACKGROUND

The objective of this study was to investigate the performance of a newly developed decision support system for the establishment of tight glycemic control in medical intensive care unit (ICU) patients for a period of 72 hours.

METHODS

This was a single-center, open, non-controlled feasibility trial including 10 mechanically ventilated ICU patients. The CS-1 decision support system (interacting infusion pumps with integrated enhanced model predictive control algorithm and user interface) was used to adjust the infusion rate of administered insulin to normalize blood glucose. Efficacy and safety were assessed by calculating the percentage of values within the target range (80-110 mg/dl), hyperglycemic index, mean glucose, and hypoglycemic episodes (<40 mg/dl).

RESULTS

The percentage of values in time in target was 47.0% (+/-13.0). The average blood glucose concentration and hyperglycemic index were 109 mg/dl (+/-13) and 10 mg/dl (+/-9), respectively. No hypoglycemic episode (<40 mg/dl) was detected. Eleven times (1.5% of all given advice) the nurses did not follow and, thus, overruled the advice of the CS-1 system. Several technical malfunctions of the device (repetitive error messages and missing data in the data log) due to communication problems between the new hardware components are shortcomings of the present version of the device. As a consequence of these technical failures of system integration, treatment had to be stopped ahead of schedule in three patients.

CONCLUSIONS

Despite technical malfunctions, the performance of this prototype CS-1 decision support system was, from a clinical point of view, already effective in maintaining tight glycemic control. Accordingly, and with technical improvement required, the CS-1 system has the capacity to serve as a reliable tool for routine establishment of glycemic control in ICU patients.

Detection of small selenium-containing proteins in tissues of the rat

The important role of selenium in the mammalian organism has been manifested by the detection of several selenoenzymes, and there are still numerous selenium-containing proteins to be identified. After in vivo labeling of rats with [75Se]-selenite, gel electrophoretic separation of the proteins in tissue homogenates and autoradiography of the labeled bands, information on the selenium-containing proteins present in the different tissues was obtained. In the separation by SDS-PAGE and two-dimensional IEF/SDS-PAGE a large number of selenium-containing proteins or protein subunits with apparent molecular masses in the range from 116 to 8 kDa could be distinguished. This range was extended by applying a modified Tricine-SDS-PAGE, which allows the determination of smaller proteins. Using this method in the separation of the homogenates of the adrenal, brain, diaphragm, epididymis, heart, kidney, liver, lung, pituitary, prostate, skeletal muscle, spleen, thymus and thyroid, four additional selenium-containing proteins with molecular masses of approximately 7 kDa, 5kDa, 4 kDa and 3kDa were detected. The 5 kDa protein and the 7 kDa protein were identified as selenocysteine-containing selenoproteins.

Speciation of selenium in the mammalian organism

As almost all of the selenium present in the mammalian organism is protein-bound, speciation is mostly concerned with the determination of the different selenium-containing proteins. Information on their distribution and their concentrations in the different tissues of the rat was obtained by means of tracer procedures which, after application of 75Se-selenite with a very high specific activity to selenium-depleted animals and electrophoretic separation of the labelled proteins, allow the determination of these compounds in the pmol to fmos range. A method was developed for the determination of selenocysteine and selenomethionine in the selenium-containing proteins. The identification of specific selenoproteins was achieved by analysis of their selenoamino acid residues and by studies on their characteristics and possible biological functions. This is being followed by the development of methods for the quantitative analysis of the selenoproteins in questions in the tissues of animals and man. In this paper the strategies and procedures used in the identification, characterization and determination of the selenium species present in the mammalian organism will be discussed.