Glycosylation of transferrin in Alzheimer's disease and alcohol-induced dementia.

Transferrin is a glycosylated metal-binding serum protein. Carbohydrate-deficient transferrin (CDT) is a marker of recent and heavy alcohol intake. A genetic variant of transferrin, TfC2, occurs with increased frequency in patients with Alzheimer's disease (AD). Hence the question arose whether, in addition to an altered amino acid sequence, there could also be a difference in the glycosylation state of transferrin in patients with dementia. Serum samples of 37 AD and 13 Alcohol-induced dementia patients as well as 10 healthy controls were analyzed for abnormal Tf variants, using isoelectric focusing followed by blotting with anti-Tf antibodies. This allowed the direct visualization of glycosylation variants of transferrin, and assessment of any increase in underglycosylated forms (di-, mono- and asialo transferrin).

National health accounts in developing countries: appropriate methods and recent applications.

Better information on the financing of the health sector is an essential basis for wise policy change in the area of health sector reform. Analysis of health care financing should begin with sound estimates of national health expenditure--total spending, the contributions to spending from different sources and the claims on spending by different uses of the funds. The member countries of the OECD have successfully established such comparative health expenditure accounts in terms of standardized definitions of the uses of funds and breakdowns by public and private sector sources. This has resulted in important research on health system differences which could explain variations in the level and composition of financing. The United States has developed a more detailed approach called National Health Accounts, which expands the OECD method into a more disaggregated 'sources and uses' matrix. In the developing countries, analysis of health expenditures has been much less systematic, despite several decades of calls by international researchers for more attention. This paper reviews previous work done in developing countries and proposes renewed attention to national health expenditures, adapting the recent experience of the United States. Because most developing countries have more pluralistic health financing structures than are found in most industrialized countries, an enhanced and adapted version of the 'sources and uses' matrix method is proposed. This method should be modified to address the relevant categories of expenditures prevalent in the developing countries. Examples of recent applications of such 'national health accounts' from the Philippines, Egypt, India, Mexico, Colombia and Zambia are presented. Experience to date suggests that development of sound estimates using this method in low and middle income countries is feasible and affordable. National health accounts estimates can significantly influence policy. They provide decision makers with a holistic picture of the health sector, showing the actual emphasis of spending and the roles of different payers. They also provide a consistent framework for modelling reforms and for monitoring the effects of changes in financing and provision. An easy to use software tool has been developed for training and data management. Regional networks of collaborating national groups are proposed as a first step in expanding use of the method and to gain both national and cross-national comparative benefits.

Artemisinin enhances heme-catalysed oxidation of lipid membranes.

Artemisinin, a sesquiterpene endoperoxide derived from a traditional Chinese herbal remedy for fevers, is a promising new antimalarial drug, particularly useful against multidrug resistant strains of P. falciparum. Despite widespread clinical use, its mode of action remains uncertain. We investigated whether its antimalarial properties could be explained by an ability to enhance the redox activity of heme, formed in the parasite food vacuole from digested hemoglobin. Artemisinin caused a sustained threefold increase, followed by a gradual decline, in the peroxidase activity of heme. It also enhanced the ability of heme to oxidize membrane lipids about sixfold. An unexpected finding was the potentiation of heme-catalysed membrane lipid oxidation by Vitamin E. The changes in redox-catalytic activity induced by artemisinin were paralleled by major changes in the absorption spectrum of heme, culminating in loss of the Soret band. We propose a model in which artemisinin binds irreversibly to heme in the parasite food vacuole, preventing its polymerization to chemically inert hemozoin, and promoting heme-catalysed oxidation of the vacuolar membrane by molecular oxygen, which leads, ultimately, to vacuole rupture and parasite autodigestion.

The iron environment in heme and heme-antimalarial complexes of pharmacological interest.

Mössbauer spectroscopy has been utilized to probe the electronic environment of iron in a number of Ferriprotoporphyrin IX complexes of relevance to malaria. The markedly different iron environments found for the complexes of hemin with quinine, chloroquine, and the Chinese herbal antimalarial artesunate suggest that these compounds act by protecting the heme from polymerization to insoluble hemozoin, and by facilitating the transport of the protected heme to the food vacuole membrane where it is able to exercise its cytotoxic redox catalytic activity. Mössbauer parameters determined here for purified malaria pigment and synthetic beta-hematin confirm the chemical identical-ness of these species. The Mössbauer spectra of the complexes are discussed in light of the proposed structures of the complexes.

Reaction between ferriprotoporphyrin IX and the antimalarial endoperoxide artesunate gives an intermediate species with enhanced redox catalytic activity.

The kinetics of the reaction between ferri(Fe(III) protoporphyrin IX (haemin) and the potent sesquiterpene endoperoxide antimalarial artesunate are shown to be consistent with a three-step, two-intermediate mechanism, with the final product possessing a degraded tetrapyrrole ring system. Microscopic rate constants for the mechanism have been evaluated. The redox catalytic capability of the haem artesunate complex is shown to be approximately fourfold that of haemin alone, suggesting a possible mechanism of action of the drug.

Xanthine oxidase inhibits growth of Plasmodium falciparum in human erythrocytes in vitro.

Malaria parasites, unable to synthesize purine de novo, use host-derived hypoxanthine preferentially as purine source. In a previous study (1990. J. Biol. Chem. 265:6562-6568), we noted that xanthine oxidase rapidly and completely depleted hypoxanthine in human erythrocytes, not by crossing the erythrocyte membrane, but rather by creating a concentration gradient which facilitated hypoxanthine efflux. We therefore investigated the ability of xanthine oxidase to inhibit growth of FCR-3, a chloroquine-resistant strain of Plasmodium falciparum in human erythrocytes in vitro. Parasites were cultured in human group O+ erythrocytes in medium supplemented, as required, with xanthine oxidase or chloroquine. Parasite viability was assessed by uptake of radiolabeled glycine and adenosine triphosphate-derived purine into protein and nucleic acid, respectively, by nucleic acid accumulation, by L-lactate production, and by microscopic appearance. On average, a 90% inhibition of growth was observed after 72 h of incubation in 20 mU/ml xanthine oxidase. Inhibition was notably greater than that exerted by 10(-7) M chloroquine (less than 10%) over a comparable period. The IC50 for xanthine oxidase was estimated at 0.2 mU/ml, compared to 1.5 x 10(-7) M for chloroquine. Inhibition was completely reversed by excess hypoxanthine, but was unaffected by oxygen radical scavengers, including superoxide dismutase and catalase. The data confirms that a supply of host-derived hypoxanthine is critical for nucleic acid synthesis in P. falciparum, and that depletion of erythrocyte hypoxanthine pools of chloroquine-resistant malaria infection in humans. of chloroquine-resistant malaria infection in humans.

Regulation of 5-phosphoribosyl 1-pyrophosphate and of hypoxanthine uptake and release in human erythrocytes by oxypurine cycling.

Uptake and release of purines by red blood cells has been shown to be markedly sensitive to changes in pH, inorganic phosphate (Pi), and oxygen concentration (Berman, P., Black, D., Human, L., and Harley, E. (1988) J. Clin. Invest. 82, 980-986). The mechanism of this regulation has been further studied. We have shown that incubation of red cells in medium containing xanthine oxidase rapidly and completely depletes intracellular hypoxanthine and causes accumulation of 5-phosphoribosyl 1-pyrophosphate (PRPP) at physiological Pi concentrations. Hypoxanthine release from intracellular IMP is strictly dependent on PRPP depletion, induced by either alkalinizing the cells or by adding excess adenine. Xanthine oxidase abolishes this dependence. Oxygen depletion enhances adenine uptake and prevents hypoxanthine release. The results suggest that hypoxanthine release is governed by PRPP-dependent recycling of hypoxanthine to IMP. We propose that PRPP accumulation in red cells is regulated by a substrate cycle, comprising hypoxanthine, IMP, and inosine. Cycle flux is controlled by Pi inhibition and 2,3-bisphosphoglycerate activation of purine-5'-nucleotidase, which converts IMP to inosine. Oxypurine cycling may account for the sensitive control of purine uptake and release by changes in pH and oxygen tension that occur physiologically.

Oxypurine cycle in human erythrocytes regulated by pH, inorganic phosphate, and oxygen.

The effect of pH, PO2, and inorganic phosphate on the uptake and metabolism of hypoxanthine by erythrocytes has been studied. Uptake of hypoxanthine and accumulation of inosine 5'-monophosphate (IMP) were markedly increased at acid pH, high external phosphate concentrations, and low PO2. Release of accumulated IMP as hypoxanthine occurred at alkaline pH values and low external phosphate concentrations. Conditions favoring IMP accumulation gave rise, in the absence of hypoxanthine, to a corresponding increase in 5'-phosphoribosyl-1-pyrophosphate. Intracellular phosphate concentrations were markedly pH dependent and a model is presented whereby hypoxanthine uptake and release are controlled by intracellular concentrations of inorganic phosphate and 2,3-bisphosphoglycerate. These allosteric effectors influence, in opposing ways, two enzymes governing IMP accumulation, namely 5'-phosphoribosyl-1-pyrophosphate synthetase and 5'-nucleotidase. These metabolic properties suggest that the erythrocyte could play a role in the removal of hypoxanthine from anoxic tissue.

Vitamin and mineral status of trained athletes including the effects of supplementation.

We measured serum concentrations of thiamin, riboflavin, nicotinic acid, pyridoxine, folate, cyanocobalamin, ascorbic acid, retinol, tocopherol, zinc, magnesium, copper, iron, and ferritin as well as hemoglobin, hematocrit, percentage transferrin saturation, and total iron-binding capacity in athletes who ingested a multivitamin and mineral supplement for 3 mo. All blood variables were normal and except for pyridoxine and riboflavin there were no significant changes in the blood concentrations of any other vitamins or minerals measured. This may have been due to variable interactions between the vitamins and minerals in the supplement that prevented their being adequately absorbed. There were no signs or symptoms of serious toxic side effects. We conclude that multivitamin and mineral supplementation was without any measurable ergogenic effect and that such supplementation is unnecessary in athletes ingesting a normal diet.

Community-based health workers: head start or false start towards health for all?

Health service delivery programs using minimally-trained community-based health workers (CHWs) have been established in many developing countries in recent years. These programs are expected to improve the cost-effectiveness of health care systems by reaching large numbers of previously underserved people with high-impact basic services at low cost. The reported experience with these programs has been mixed, raising questions about whether the community health worker is an optimal vehicle for extending primary health care. This review of six large-scale community-based worker programs suggests that they have succeeded in some of their objectives but not in others. CHWs increase the coverage and equity of service delivery at low cost compared with alternative modes of service organization. However, they do not consistently provide services likely to have substantial health impact and the quality of services they provide is sometimes poor. Large-scale CHW systems require substantial increases in support for training, management, supervision, and logistics. The evidence suggests that, in general, their potential has not been achieved in large routine programs. Further development of these programs is needed to reinforce their successes and assure that they are adequately supported as an integral component of the basic health system.

Prenatal diagnosis of cystic fibrosis in South Africa.

Prenatal diagnosis of cystic fibrosis (CF) has been made possible by the finding that the activity of various enzymes derived from the microvillar membranes of the fetus is decreased in 2nd trimester amniotic fluid. Gamma-glutamyl transpeptidase, aminopeptidase M and the phenylalanine-inhibitable form of alkaline phosphatase (AP) have been found to be of most diagnostic use in this respect, the odds of the fetus being affected with CF being 28:1 if the AP test is positive. When couples have already had a child with CF, pregnancies are being monitored by these methods at the University of Cape Town.

Village health workers in Java, Indonesia: coverage and equity.

Village health workers are often the main vehicle for promoting the primary health care approach in developing countries. Services provided by these workers are expected to be more appropriate to the health needs of populations than those of clinic-based services, to be less expensive and to foster self-reliance and local participation. Because village workers are more accessible and acceptable to clients in their communities, they are expected to improve the overall coverage of services as well as equity--increased service use by poorer individuals and households. This paper presents research on coverage and equity from village health worker programs in Java, Indonesia. Rural health and nutrition projects in Java using village-level volunteers with limited training have grown since the early 1970s to include large national programs managed by the government's rural health system. Volunteer village workers are now the most extensive link between the rural population and the formal health service structure. Previous research on coverage and equity of these village worker activities is reviewed and results from the author's own study are presented. Services provided by village health workers achieve significantly higher levels of population coverage than similar clinic-based services. In most cases, village workers show no bias towards better-off clients and they may favor poorer beneficiaries. These findings show that village workers are meeting the coverage and equity objectives of the primary health care approach. However, some of the research reviewed raises questions about the ability of village worker activities to maintain these results over a longer period. The rapid expansion of these programs requires continued research, not only on coverage and equity, but also on health outcomes, costs, and participation.

Epsilon-aminocaproic acid-induced myopathy. A case report.

The prolonged administration of epsilon-aminocaproic acid (EACA) resulted in the development of severe proximal myopathy associated with high plasma creatine kinase values, rhabdomyolysis, myoglobinuria, and mild hyperbilirubinaemia. Withdrawal of the drug led to spontaneous resolution of the clinical and biochemical syndrome. Structural and enzyme studies of a biopsy specimen of the involved skeletal muscle supported the presence of subclinical myopathy. The mechanism whereby EACA produces its toxicity in muscle may in part be due to inhibition of cathepsin D, but the possibility that other proteases are involved has not been excluded. The fact that this clinical syndrome is rare despite the widespread use of EACA may be because it only occurs in subjects with a subclinical skeletal muscle disorder which is unmasked by the drug.

Selective primary health care: is efficient sufficient?

Developing countries are increasingly using economic evaluation methods to assess and plan their health services. Inappropriate application of these methods may lead to serious errors in developing primary health care strategies. In 'Selective Primary Health Care', Julia Walsh and Kenneth Warren present a logical approach to health planning based on cost-effectiveness techniques. Their paper is a timely example of the risks of using simple technical criteria to plan solution to complex public health problems. Cost-effectiveness is not a sufficient criterion for planning primary health care. Related issues are discussed in these comments. As an alternative, a multiple-objective approach is suggested.

Ketonuria in pregnancy--with special reference to calorie-restricted food intake in obese diabetics.

Early morning ketonuria, as judged by Ketostix testing, occurred in 19% of urine samples from insulin-independent diabetic pregnant women eating 1000 calorie diets, in 14% from diabetics on higher calorie diets, and in 7% of urines from nondiabetic pregnant women. Ketostix test was never found to be positive in blood, even when it was 2+ in urine samples, and acetoacetate levels were always below 1 mmol/L. Enzymatic estimations of acetoacetate (AA) and beta-hydroxybutyrate (BB) in urine and plasma samples revealed (1) no significant differences in range or mean between the groups receiving different restricted diets or full diets, the highest value observed for plasma AA being 0.34 mmol/L; (2) that Ketostix became positive at a concentration of AA above 1 mmol/L and that such a value in urine corresponded to plasma levels of between 0.06 and 0.1 mmol/L, i.e., double the normal; and (3) a 50-100-fold increase in urine AA when blood levels exceeded 0.08 mmol/L. Neonates born to diabetic mothers with ketonuria had no fetal distress or asphyxia neonatorum. The lowest Apgar score at 5 min was 8; 80% of neonates had a score of 10. Hence, positive Ketostix tests in urine samples do not indicate toxic levels in the blood, and a 1000 calorie diet for obese pregnant diabetics appears to be safe as regards neonatal outcome.