Evaluation of various rapid chloride tests for assessing urinary NaCl excretion.

BACKGROUND/AIMS: The evidence linking NaCl intake to high blood pressure and probably to other diseases has become stronger. Therefore, a population-wide reduction of NaCl intake is generally recommended. Measuring NaCl excretion in urine is the preferred method for estimating dietary NaCl intake. Rapid tests measuring urinary NaCl excretion might be useful for self-monitoring the individual NaCl consumption. METHODS: The accuracy of four rapid tests measuring chloride content in urine was assessed. Three tests were originally not designed for urine analysis, but for water and food analysis. Totally 204 urine samples were analysed both with the 4 different rapid tests and with quantitative routine laboratory procedures for chloride and sodium. RESULTS: Chloride and sodium were highly correlated (r = 0.96), indicating chloride determination as a reasonable method to assess sodium and NaCl contents in urine. Accuracy of the rapid tests was acceptable in three cases. The drawback of two tests was their narrow calibration range, so that most urine samples had to be diluted. Use of one test showed problems in interpreting its results because the decolouration of the test pads was difficult to recognize. CONCLUSION: It is concluded that rapid chloride tests designed for water analysis might be suitable to determine NaCl in urine samples.

[Definition of "salt sensitivity"]. / Definition von "Salzsensitivität".

To examine how the term "salt sensitivity" has heretofore been defined, two medical data bases, DIMDI and MEDLINE were searched. 32 clinical studies, published between 1978-1992 and using the terms salt-, sodium- or sodium chloride-sensitive or sensitivity were found and analysed. Salt sensitivity was experimentally determined and applied in quite varied ways to normotensive and hypertensive persons. There were three types of studies: in type 1 (n = 15), a phase of low sodium intake was followed by one with a high intake; in type 2 (n = 8), a phase of high or "normal" sodium intake was followed by a low intake one; in type 3 (n = 9), there was a randomized sequence of differing sodium intake phases, in some cases with cross-over. It is concluded from these studies that there is insufficient evidence to distinguish between salt sensitive and salt insensitive subjects. Consequently scientific discussion of this question should not lead to hypertensives being discouraged from reducing their salt intake.

Effect of amino acid based dialysis solution on peritoneal permeability and prostanoid generation in patients undergoing continuous ambulatory peritoneal dialysis.

The acute effect of amino acid based dialysis solution on peritoneal kinetics of amino acids and plasma proteins in comparison to conventional glucose-based dialysate was studied in 9 patients with end-stage renal failure on continuous ambulatory peritoneal dialysis. Instillation of 2.6% amino acid solution resulted in raised plasma concentrations of all essential amino acids included in the dialysis fluid (p less than 0.005). The amino acid solution induced an augmented leakage of plasma proteins into the dialysate at all dwell times investigated (1-8 h). After a dwell time at 8 h, the dialysate total protein increased from 2.62 +/- 0.45 g with glucose dialysate to 3.85 +/- 0.42 g with amino acid solution (p less than 0.05). Corresponding results were obtained for beta 2-microglobulin, albumin, transferrin, IgG, and for the non-essential amino acids alanine, citrulline, and glutamine (p less than 0.025) not included in the initial amino acid composition of the dialysis fluid. During the use of amino acid based dialysis fluid, the effluent prostaglandin E2 concentration increased by more than 80% in comparison to glucose dialysate (p less than 0.025). The augmented loss of proteins induced by the amino acid solution was positively correlated with increased dialysate prostaglandin E2 (r = 0.8894; p less than 0.001). Peritoneal ultrafiltration was not affected by the use of amino acid based dialysate fluid. The present results indicate that amino acid based dialysis fluid enhances the peritoneal permeability for plasma proteins and amino acids, probably mediated by locally generated prostanoids.

Obesity in Europe.

The high prevalence of obesity in Europe is similar to that in other industrialized areas. Obesity and its related diseases, such as hypertension, hyperlipidemia, diabetes, and hyperuricemia, have become a major problem, particularly in terms of cost. Prospective studies in Scandinavia strongly suggest obesity and its related diseases lower life expectancy. Divergent results from the Seven Countries Study are critically discussed.

Studies on thromboxane B2 and prostaglandin E2 production in the course of murine autoimmune disease: inhibition by oral histidine and zinc supplementation.

Synthesis of both prostaglandin E2 and thromboxane B2 in liver and kidney tissue of NZB/W F1 hybrid mice was found to increase with advancing age. The rise in prostanoid generation coincided with the appearance and progression of the spontaneous systemic lupus erythematosus (SLE)-like disorders seen in these mice. Substitution of a diet supplemented with histidine (50 g kg-1 dry weight) and/or zinc (160 mg kg-1 dry weight) suppressed the autoimmune disease associated increase in prostanoid generation. The parent NZB and NZW strains also revealed an age-dependent increase in prostanoid synthesis whereas no age-related changes of tissue prostanoid generation were seen in healthy DBA-2 and C57-BL/6 control mice. In a previous study [Schwerdtfeger et al. 1980] a protective effect of histidine and/or zinc on the course of SLE-like disease in NZB/W F1 mice was reported. The current work suggests that this effect may in part have been mediated by the modulation of cellular arachidonic acid metabolism. The proposal that prostanoids are involved in the pathogenesis of autoimmune disease in NZB/W F1 mice is supported by these results.

Effect of L-histidine in vivo on human platelet function and arachidonic acid metabolism.

The effect of the amino acid l-histidine on human platelet function and arachidonic acid metabolism was studied in 18 healthy subjects with increased spontaneous platelet aggregation. The participants received placebo or l-histidine 3g/day for 7 days. The intake of l-histidine reduced the degree of spontaneous platelet aggregation (p less than 0.05) and inhibited the generation of platelet TXB2 by 47% (p less than 0.001) whereas platelet PGE2 synthesis was not affected. The mean l-histidine plasma concentration increased from 83.1 +/- 2.4 to 108 +/- 8.1 mumol/l (p less than 0.01) during the study. L-histidine was found to be an effective inhibitor of spontaneous platelet aggregation and platelet TXB2 generation. The present data verify interactions of histidine with human platelet function, probably mediated by arachidonic acid metabolites.

Kidney independent serine synthesis in the rat. Effect of dietary serine and glycine restriction.

The potential role of the kidney in renal serine synthesis was elucidated in rats following dietary serine as well as serine and glycine depletion for 6 weeks. Serine deficient diet caused a significant rise in blood serine and glycine values. In contrast, blood glycine concentration decreased significantly following serine and glycine depletion, whereas blood serine levels remained unchanged. Bilateral nephrectomy caused a significant decrease of blood serine values of control and serine deficient rats. Serine concentration, however, was not affected by bilateral nephrectomy following serine and glycine deficiency indicating kidney-independent serine synthesis under these conditions. There was a significant increase of blood lactate and pyruvate levels under serine and serine/glycine deficient diet compared with control animals, whereas blood ketone bodies fell. In contrast, 24 h after bilateral nephrectomy blood ketone bodies rose and blood lactate and pyruvate concentrations decreased significantly. 24 h after bilateral nephrectomy there was a marked rise in blood citrate values of female rats compared with male animals indicating sex dependency of kidney citrate metabolism in the rat.

Synthetic amino-acid diet prolongs survival in autoimmune murine disease.

The effect of substituting a fully synthetic diet for standard laboratory pellet feed on the course of spontaneous autoimmune disease in New Zealand Black/White hybrid mice was examined. Delays in the development of anti-nuclear antibody, proteinuria and circulating immune complexes were seen; the survival was markedly prolonged. This type of dietary manipulation has a beneficial effect on the course of murine autoimmune disease.

[Potassium and sodium content of hospital general diets--comparison of calculated and analytical values]. / Zur Frage des Kalium- und Natriumgehaltes von Klinik-Vollkost--Gegenüberstellung von Berechnungen und Analysen.

Our knowledge on the composition of general hospital diets still relates virtually exclusively to calculated values derived from food tables. To find out how relevant these are for the estimation of potassium and sodium contents of the general diet data were chemically analysed and compared to table values. The chemical analysis of daily general diet portions resulted in a mean value of 1.86 g potassium/day in contrast to the calculated mean value of 2.72 g/day. As far as the sodium contents of the general diets are concerned, the picture was reversed (calculated: 3.16 g/day, analysed: 5.20 g/day). These results suggest that only chemical analysis of hospital diets guarantees an adequate supply of potassium and sodium.

[Double blind study of the influence of aristolochic acid on granulocyte phagocytic activity]. / Doppelblindstudie zur Beeinflussung der Phagozytosefähigkeit von Granulozyten durch Aristolochiasäure.

In two double blind studies, separated by a time interval, the influence on phagocytic activity of peripheral granulocytes was investigated by aid of 3H-labelled staphylococci following administration of therapeutic doses of aristolochic acid, a nitrophenanthrene carboxylic acid derivative, to 12 healthy test subjects. Both double blind studies showed that aristolochic acid in a dosage of 0.9 mg/d produced a definite increase in phagocytic activity in healthy test persons after the third day of treatment; this increase reached a maximum within a 10-day treatment period between the seventh and tenth days; following discontinuation of treatment normal values were recorded again within a week. Other laboratory parameters investigated were not influenced.