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.

International collaborative assessment study of the AHD [575] 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 [AHD[575]] 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 [AHD[575]] method was evaluated against the HiCN method, with blood samples drawn from healthy and sick subjects. The results indicate that the AHD[575] method is suitable for measuring haemoglobin in laboratories at all levels

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.

Health care in the developing world: need for appropriate laboratory technology.

Health care technology is rapidly advancing, and the development of equipment based on new principles has had a strong impact on laboratory services in Western countries. The use of such technologies frequently creates problems in countries of the Third World, because the effects of several interacting elements are not always taken into account. Not only technical factors but also socioeconomic and political factors, as well as differences in diseases in developing countries, must be considered. Standardization of equipment and methodology, and adaptation to local health systems, will facilitate improvement of laboratory services. Training and incentives for local initiatives are fundamental elements for the provision of cost-effective health care.

Kinetic analysis of the clotting system in the presence of heparin and depolymerized heparin.

The kinetics of the activation of the plasmatic clotting system in the presence of heparin and depolymerized heparin (Kabi 2165), respectively, was compared with the kinetics of activation in plasma with isolated factor deficiency. Measurements were made with a chromogenic substrate method using Tos-Gly-Pro-Arg-p-nitroanilide acetate. The extinction curves were analyzed to determine the characteristics of a curve that was fitted to the experimental data to sufficiently describe the slope of the curves by constants. In the activated extrinsic clotting system, the action of heparin and depolymerized heparin results in a distribution pattern for the two relevant constants. K(1), defining the time of the point of inflection of the curve, and K(2), relating to the slope of the curve at the point of inflection, which is identical with the pattern observed in plasma with factor II deficiency. This distribution pattern can be explained by an inhibitory reaction on factor IIa, which is accelerated by the anticoagulant. In contrast, the pattern of K(2)/K(1) for the activated intrinsic system is identical with the pattern for plasma with factor X deficiency. Qualitative differences in the action of heparin and depolymerized heparin are not evident. The investigation confirms that the molecular action of heparin and depolymerized heparin as accelerators of the plasmatic clotting system is qualitatively the same. However, their action in the extrinsic and intrinsic system has different effects. Furthermore, the study reveals that constant K(2) is a more sensitive indicator to measure low heparin and depolymerized heparin activities than K(1) or its equivalent, the clotting time.

Simulation of the extrinsic pathway of the plasmatic clotting system.

Activation of the extrinsic plasmatic clotting system was simulated in a computerized analysis. The results were compared with previously described experimental investigations in plasma with isolated clotting factor deficiency, which led to the conclusion that the sequence of patterns for constants of a function describing the extinction curves is related to the sequence of steps of clotting factor activation. The kinetics of activation resulting in extinction curves that correspond to the curves obtained from experimental measurements are described by sets of stiff coupled linear differential equations. The set of functions can be numerically solved without further approximations. As for experimental extinction curves the simulated extinction curves are characterized by an empirical function with three constants. The distribution patterns for the constants are qualitatively similar to experimental patterns, if the following assumptions are made: (1) feedback reaction occurs from factor IIa via factor V, and (2) the conversion of factor II by factor Xa occurs at a rate considerably slower than the conversion of factor II by the prothrombinase complex. A feedback reaction by factor Xa via factor VII accelerates the formation of factor X, although the distribution pattern remains similar to the distribution pattern for a mechanism without the feedback reaction, provided that the initial activation of factor X occurs at a fast rate. A feedback reaction by factor Xa via factor V in addition to the feedback reaction by factor IIa via factor V accelerates the activation, while the pattern distribution remains unchanged. The simultaneous inhibition of factor Xa and factor IIa by antithrombin III does not change the pattern distribution, while the formation of activated factor II is decelerated.

Basic laboratory procedures in clinical bacteriology / Basic laboratory procedures in clinical bacteriology

Communicable diseases are the most common cause for death in developing countries, and their diagnosis and treatment represent a significant challenge to the health services in those areas. To ensure accurate identification of causative microorganisms, laboratories need to use standard procedures for microbiological investigations and susceptibility testing, and to implement an effective programme of quality assurance

This manual is a practical guide, for use by laboratory workers in health centres and district hospitals, to the procedures to be followed in obtaining specimens, isolating and identifying bacteria, and assessing their resistance to antibiotics. It covers bacteriological investigation of blood, cerebrospinal fluid, urine, stool, sputum, pharyngeal and genital specimens, and purulent exudates. Particular attention is given to the need for quality control of all laboratory procedures. A list of media and reagents needed for the isolation and identification of the most common bacterial pathogens is included, together with an indication of their relative importance for the intermediate laboratory. This list is intended for adaptation to local circumstances

Computerized analysis of the in vitro activation of the plasmatic clotting system.

We analyzed the kinetics of the clotting system by a chromogenic substrate method in plasma with isolated factor deficiency. The sigmoidal extinction curve obtained was mathematically described by an equation with four constants K(i) relating to the activity of clotting factors and to the concentration of fibrinogen. The analysis of constants obtained from dilution series of factor-deficient plasma revealed a distribution pattern differing from one factor to another both for the extrinsic and the intrinsic system. The observations indicated that isolated factor deficiency may be identified through the analysis of 2 of the 4 constants, K(1) being the time value of the point of inflection of the extinction curve and K(2) a measure for the slope of the curve at the point of inflection. The observation was confirmed by a reclassification through nearest-neighbor discriminant analysis of K(1) and K(2) which revealed a correct classification in the pathological range for all factor deficiencies investigated with the exception of factors VIII and IX, the distribution patterns of which were superposed within the limits of distribution.

Selective removal of low-density lipoproteins from plasma by polyacrylate-coated Fractogel in vitro and in experimental extracorporeal perfusion.

Polyacrylate, covalently bound to Fractogel, was tested as a sorbent for lipoproteins from human plasma in a perfusion column. Experiments in vitro indicated complete elimination of low-density lipoproteins from citrated plasma. No binding of high-density lipoproteins, fibrinogen, or the complement factors C3 and C4 was observed. Biocompatibility was demonstrated by extracorporeal plasma perfusion in sheep. The results indicate the potential use of polyacrylate-coated Fractogel for the removal of low-density lipoproteins from plasma ex vivo.

Long-term effect of magnesium pyridoxal 5-phosphate glutamate in rabbits developing hypercholesterolemia.

36 male rabbits were fed with a diet enriched with 20 g cholesterol/kg for a period of 8 weeks under a strict daily dietary control. Magnesium pyridoxal 5-phosphate glutamate (MPPG, Sedalipid) was supplemented to the diet at different quantities. Hypercholesterolemia developed later and less pronounced in animals receiving a medium or high dose of MPPG. Microscopical analysis indicated a protective effect of MPPG on calcium deposition in the aorta. The fatty acid pattern in serum showed only minor differences and was unchanged in liver extracts in animals supplemented with MPPG. This observation suggest that MPPG may act on the mechanism of cholesterol absorption in the intestine.

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.

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.