International collaborative assessment study of the AHD575 method for the measurement of blood haemoglobin.

Accurate, economical methods for haemoglobin determination by laboratories in countries with limited resources are not available. This report provides the results of an international collaborative study evaluating the alkaline haematin detergent (AHD575) method as a reference method for laboratory services with limited resources. The study included 6 laboratories; 3 in East Mediterranean countries, 1 in East Africa and 3 in Europe. The (AHD575) method was evaluated against the HiCN method, with blood samples drawn from healthy and sick subjects. The results indicate that the AHD575 method is suitable for measuring haemoglobin in laboratories at all levels.

The surface charge of human glutaraldehyde-fixed erythrocytes.

We measured the number of charged residues at the surface of fresh human erythrocytes after fixation with glutaraldehyde by polyelectrolyte titration using polycations of different chemical composition and various molecular weights. Independent of the reagents used, the number was (8.5 +/- 1.5) X 10(8) negatively charged residues per cell. The surface charge density of 6.3 e/nm2 is considerably higher than that calculated from the electrophoretic mobility for which the surface charge density is calculated to be 0.09 e/nm2.

Protein restriction in the conservative management of uremia.

Protein-restricted diets are widely used in the dietary management of uremia. These diets are undoubtedly effective in ameliorating many aspects of the uremic syndrome. However, there is no consensus as to whether diets providing less than 0.6 g/kg per day of protein are nutritionally adequate and capable of preventing the wasting syndrome. Wasting is common in the adult patient with renal insufficiency as is growth failure in the uremic child. There is some evidence that wasted patients do less well on hemodialysis and are more prone to infection. Experimental studies in uremic animals point ot diminihsed efficiency of utilization of protein, increased gluconeogenesis from animo acids, and increased catabolism of protein in the fasting state; in addition, the metabolism of a number of individual amino acids is altered in uremia. In view of these multiple abnormalities, it would seem unwise to routinely provide less than the Recommended Daily Allowances of protein. More recent developments, i.e., supplementation of essential amino acids and perhaps alpha keto acids, may provide useful alternatives. One important aspect of dietary management, i.e. prevention of hyperlipidemia, has attracted surprisingly little attention so far. Therapy with protein restricted diets in nondialyzed uremic patients has to compete with other modalities of treatment currently available, i.e., hemodialysis and transplantation, in providing optimal medical rehabilitaiton of the patient.

Effect of lipoprotein-X on hepatic cholesterol synthesis.

The effect of different lipoproteins (lipoprotein-X and lipoprotein-B; LP-X and LP-B) on hepatic cholesterol synthesis was studied in vivo in rats. Lipoproteins were continuously infused into rats for 16 hours so that 24 mg cholesterol/100 g body weight were applied. Serum cholesterol level was nearly doubled after the infusion period. Lipoprotein electrophoresis revealed the predominance of the infused lipoprotein in the serum. LP-B infusion caused a reduction of cholesterol synthesis (42% of control values) and reduced the increased cholesterol synthesis of bile fistula rats to values below normal. LP-X did not reduce hepatic cholesterol synthesis significantly nor did it normalize the enhanced synthesis following biliary diversion. However, hepatic free cholesterol concentration increased after LP-X infusion. The effect of LP-X on liver cholesterol synthesis is similar to that of lecithin: cholesterol dispersions. The failure of LP-X to exert a feedback inhibition on cholesterol synthesis may therefore contribute to the mechanism of hypercholesterolemia in obstructive jaundice.

Sitosterol in juvenile type II hyperlipoproteinemia.

The effect of beta-sitosterol on plasma lipids and lipoproteins was evaluated in a randomized double-blind cross-over trial in 15 children and adolescents with familial hypercholesterolemia over a period of 6 months. Twelve patients completed the study, with good adherence to drug intake. Sitosterol lowered the plasma total choelsterol by 6%, LDL cholesterol by 7% and HDL cholesterol by 15% (P less than 0.05). This insufficient response of total and LDL cholesterol and the marked fall of HDL cholesterol appears to advise against the use of beta-sitosterol granulate in juvenile type II hyperlipoproteinemia.

Atherogenesis in experimental uremia.

The development of experimental atherosclerosis was studied in subtotally nephrectomized rats which were subjected to preimmunization with horseradish peroxidase and subsequent feeding with atherogenic diet. Both in sham-operated pair-fed control animals and in uremic animals, the atherogenic diet caused hyperlipemia which was more pronounced in uremic than in control animals (control animals: triglycerides 1.11 +/- 0.04 mmol/l; cholesterol 5.82 +/- 0.21 mmol/l; uremia: triglycerides 1.33 +/- 0.06; cholesterol 10.9 +/- 0.31). An increase of cholesterol was seen both in the VLDL and in the LDL fractions. Despite more pronounced hyperlipemia, lipid concentration in the aortic wall was not increased nor were more marked histological abnormalities encountered in the aorta of uremic animals (cholesterol-fed control: cholesterol 95.4 +/- 4.4 micrograms/mg protein; phospholipids 2.42 +/- 0.9 micrograms/ml protein; cholesterol-fed uremia: cholesterol 96.8 +/- 4.9; phospholipids 2.52 +/- 0.8). The results suggest that despite hyperlipemia short-term experimental renal insufficiency does not promote atherogenesis.

"Low dose" colestipol in children, adolescents and young adults with familial hypercholesterolemia.

The effect of colestipol on plasma lipids and lipoproteins was studied in children, adolescents and young adults with familial hypercholesterolemia. O.125 g or 0.25 g/kg body weight were given in randomized sequence for period of 4 weeks. Total cholesterol was lowered by 13 and 18% with the smaller and larger dose , respectively, and LDL cholesterol lowered by 15% with the smaller and 12% with the larger dose. HDL cholesterol rose by 18 an 32%. LDL composition before and during the study was abnormal due to a markedly reduced triglyceride content. "Low-dose" colestipol is less effective lowering total plasma and LDL cholesterol than conventional doses but may, due to very few side effects, by advantageously used in cases of familial hypercholesterolemia when plasma cholesterol levels after dietary management are only 15-20% above normal.

The association of hyperlipoproteinemia with dysimmunoglobulinemia.

In a study of the immunoglobulin concentrations in an urban population and in patients with hyperlipoproteinemia we observed significant positive correlations between serum triglycerides and IgA independent of sex, age and body weight. In men serum triglycerides also correlated with IgG and IgM, and serum cholesterol with IgA. The prevalence of hyper- and hypoimmunoglobulinemia was significantly higher in hyperlipidemic than in normolipemic subjects. We propose that the occurrence of hyperlipoproteinemia with hypoimmunoglobulinemia may be caused by different pathobiological mechanisms than the occurrence with hyperimmunoglobulinemia.

Acute dietary effects on diurnal plasma lipids in normal subjects.

The effects of different dietary carbohydrates and different dietary fats as well as of differently spaced dietary constituents on 24-h plasma free fatty acids and triglycerides were determined in healthy young males. If, in an isocaloric diet containing 15-20% protein, 37% fat and 43--48% carbohydrates, sucrose is compared with glucose, 24-h plasma triglycerides are significantly higher with the former carbohydrate. When palm oil (mainly 16 : 0 fatty acids) is compared with olive oil (mainly 18 : 1 fatty acids), 24-h triglycerides are significantly higher with the latter. If the carbohydrate component of a mixed meal is removed, alimentary lipemia is considerably greater. Our findings supplement long term studies regarding the effect of different dietary fats and carbohydrates on plasma lipids and allow calculation of "upper normal limits" for 24-h plasma triglycerides and free fatty acid patterns on isocaloric diets of "prudent" composition.

Effect of prolonged exercise on serum lipids and lipoproteins.

It has been shown that physical exercise lowers serum triglyceride levels and may increase high density lipoprotein-cholesterol levels. Understanding of the mechanisms responsible for these beneficial adaptations is still incomplete. Twenty-six men, who played soccer continuously for 64 hours to establish a world's record, were monitored for acute changes in lipid metabolism. Food intake was determined before and during the exercise period. Blood specimens were taken before and repeatedly during the match for the measurement of triglycerides (TG), total cholesterol (CH), glycerol, apolipoprotein A-I (apoA-I), and cholesterol in various lipoprotein fractions (quantitative lipoprotein electrophoresis). During exercise TG levels decreased from 116 +/- 26 to 66 +/- 13 mg/dL and CH from 180 +/- 22 to 135 +/- 25 mg/dL. Both TG and glycerol showed an initial increase followed by a continuous decrease. Alpha-CH increased by 19% whereas beta-CH and pre-beta-CH decreased markedly (39% and 78%, respectively). In contrast to alpha-CH, apo A-1 fell only slightly by 10%. These results indicate that the effect of chronic exercise on lipids and lipoproteins can be mimicked by acute prolonged exercise. Similar mechanisms may be involved in these adaptations. Moreover, the extreme length of physical exertion substantially lowered CH.

The effect of polycations on the inhibitory action of antithrombin III on thrombin in the absence and presence of polyanions.

Polycations of biological and synthetic origin inhibit the action of AT III on thrombin activity. The effect is more pronounced with increasing molecular weight of branched polycations. Quantitatively protamine causes the same effect as quaternized polycations on the basis of charge equivalence. The accelerating effect of heparin or potassium polyvinylsulfate for the inhibitory action of AT III is abolished by charge equivalent amounts of polycation. The observations indicate a dual action of polycations in the heparin/AT III/thrombin interaction.

24-Hour patterns of blood sugar, plasma insulin and free fatty acids in patients with primary endogenous hyperlipoproteinemia on isocaloric diets containing 30, 43 and 79 cal% carbohydrates.

10 patients with primary, endogenous hypertriglyceridemia (type IV hyperlipoproteinemia) underwent three different isocaloric dietary regimes of 10 days duration each. The diets contained either 30, 43 or 79% of calories as carbohydrate with 20% of calories from protein. Analyses of insulin, blood sugar and free fatty acids were conducted on the last day of each dietary period, at frequent intervals. There were no differences in either fasting or diurnal blood sugars with the different diets. Insulin levels were positively correlated with the amount of carbohydrate in the diet and there was an inverse correlation between the carbohydrate contents of the diets and circulating free fatty acid levels during waking hours. Since glucose tolerance is maintained, and diurnal plasma lipid levels are lowest with the low fat regime, such diets may be advantageously used for patients with endogenous hypertriglyceridemia.

24-hour patterns of blood sugar, plasma insulin and free fatty acids in patients with primary endogenous hyperlipoproteinemia on isocaloric diets containing 30, 40 and 79 cal% carbohydrates.

10 patients with primary, endogenous hypertriglyceridemia (type IV hyperlipoproteinemia) underwent three different isocaloric dietary regimes of 10 days duration each. The diets contained either 30, 43 or 79% of calories as carbohydrate with 20% of calories from protein. Analyses of insulin, blood sugar and free fatty acids were conducted on the last day of each dietary period, at frequent intervals. There were no differences in either fasting or diurnal blood sugars with the different diets. Insulin levels were positively correlated with the amount of carbohydrate in the diet and there was an inverse correlation between the carbohydrate contents of the diets and circulating free fatty acid levels during waking hours. Since glucose tolerance is maintained, and diurnal plasma lipid levels are lowest with the low fat regime, such diets may be advantageously used for patients with endogenous hypertriglyceridemia.

Rapid development of immunoprecipitins in agarose gel.

A procedure for the rapid development of immunoprecipitins in agarose gels has been developed using polyanion precipitation after immunoelectrophoretical separations. Excellent results are obtained for serum apolipoproteins, immunoglobulins and other proteins. It is shown that quantitative determination of apolipoprotein B in hyperlipemic serum and isolated lipoproteins is affected by immunoprecipitated complexes when rocket immunoelectrophoresis is used. This effect can be avoided by addition of polyvinylpyrrolidone.

Unchanged hormone sensitivity of rat fat cell adenylate cyclase in uremia.

The sensitivity to hormones of the fat cell adenylate cyclase system was tested in uremic rats and in pair-fed control animals. Basal enzyme activities averaged 1.25 nmoles of cAMP formed per mg protein per 15 min in controls compared to 1.30 nmoles cAMP/mg protein/15 min in fat cell ghosts obtained from uremic rats. NaF caused an approximately 4-fold stimulation of enzyme activities in both systems. It was shown that parathyroid hormone should be included amongst the hormones which act as stimulators of the enzyme system. The responsiveness of the rat fat cell adenylate cyclase system towards saturating concentrations of ACTH, glucagon, epinephrine and parathyroid hormone was not altered in the presence of chronic renal failure.

Diet and high density lipoproteins.

The acute and subacute effects of different diets on serum high density lipoprotein (HDL) cholesterol concentration and/or HDL composition are described. In obese normolipemic, hypercholesterolemic (type II) and hypertriglyceridemic (type IV) patients, low HDL cholesterol values remained low during total starvation for 2 weeks. Prudent diets in patients with type II and IV hyperlipoproteinemia had no significant effects on HDL cholesterol within 3 weeks, whereas in normal individuals, a high carbohydrate diet given for 10 days caused significant decreases in HDL cholesterol with concomitant increases in HDL triglycerides as compared to a high-fat diet. The HDL triglyceride fatty acid composition changed in healthy volunteers during the day, depending on the type of ingested fat. The data demonstrate the possibility of acute manipulations of HDL in normal patients and the difficulties of normalizing low HDL cholesterol levels in patients by dietary means. Additional information on the function of HDL is desirable before the therapeutic manipulation of HDL cholesterol or other constituents of HDL can be evaluated regarding their effectiveness in the prevention of ischemic vascular disease.

Phosphate, calcium and lipid metabolism.

Ca and Pi interact with lipid metabolism in several different ways. The enzymes of lipolysis and lipogenesis are sensitive to Ca. Ca and Pi concentrations affect insulin secretion and insulin action. Raising intestinal Ca lowers serum cholesterol and triglycerides presumably by sequestration of cholesterol and bile acids. Administration of vitamin D or increased sensitivity to vitamin D raise serum cholesterol levels. PTH acts primarily by activating adipose tissue lipase. Increased FFA delivery to the liver should increase hepatic lipoprotein synthesis. Experimental data in secondary hyperparathyroidism of renal insufficiency are consistent with this notion. Clinical observations in primary or renal secondary hyperparathyroidism, however, are not explicable by this simple schema.

The World Health Organization's role and future plans in laboratory standardization.

WHO is monitoring health care and the status of health of the population in each of its member states. The statistics provides valuable information for the comparison of the effectiveness of different health systems. As part of its global responsibility on health WHO issues international reference materials (IRMs), assigns international nonproprietary names for therapeutics (INNs), publishes guidelines for good manufacturing practice (GMP) and good laboratory practice (GLP) and, in collaboration with international professional organizations, makes recommendations towards achieving global harmonization of clinical laboratory investigations.