Serum copper concentration in adults with acute, uncomplicated falciparum malaria infection.

Serum copper concentration was measured in 80 adult patients (40 males and females each; age range: 18-40 yr) presenting with acute, uncomplicated falciparum malaria infection and a control group of 20 age-matched, healthy individuals. The mean serum copper concentration was 109.0 +/- 40.0 microg/dL in healthy individuals. Both male and female patients were found to have a significantly decreased serum copper concentration (p < 0.05). In the male patients, the mean serum copper concentration decreased by 33.95%, whereas it dropped by 38.53% in their female counterparts. A compromised enzymatic antioxidant defense capability, particularly superoxide dismutase (SOD) activity, has been reported in patients with falciparum malaria infection. Because SOD activity is dependent on copper, the ineffective SOD activity can be related to the decrease in the concentration of copper during the infection. Low serum copper can also contribute to the ineffective immune response of the host to the antigenic challenge of the falciparum parasite because copper is also important for normal immune function.

Potential role of serum magnesium measurement as a biomarker of acute falciparum malaria infection in adult patients.

Serum magnesium concentration was measured in 80 adult patients (age range: 18-40 yr) presenting with acute, uncomplicated falciparum malaria infection and a control group of 20 age-matched, healthy individuals. The mean serum magnesium concentration in the patients was 1950.0 +/- 10.0 microg/dL. The control serum magnesium was 640.0 +/- 40.0 microg/dL. This represents an over threefold increase in serum magnesium levels above normal value, p < 0.01. The key pathogenic event in acute falciparum malaria infection is the hemolysis of both infected and uninfected red blood cells. Therefore, the increased serum magnesium concentration might occur because of the hemolysis arising from erythrocytic merogony because red blood cells contain high amounts of magnesium. In conclusion, the increased serum magnesium has potential application as a biomarker of acute falciparum malaria infection in adults.

Total serum lactate dehydrogenase activity in acute Plasmodium falciparum malaria infection.

INTRODUCTION: Lactate dehydrogenase (LDH) activity was assayed in the sera of 76 adult male and 76 adult female patients within the age group of 18-40 years presenting with acute, uncomplicated Plasmodium falciparum malaria infection and a control group of 80 healthy adults within the same age group. METHODS: Patient selection and pre-qualification were done by simple random sampling of individuals presenting at the Bauchi Specialist Hospital Outpatient Department with a history of fever and malaise within a period of one to eight days, and who were confirmed to be infected with the P. falciparum malaria parasite by microscopical examination of Giemsa-stained thin blood slides. RESULTS: The mean serum LDH activity in male patients was found to be 789.4 +/- 35.0 IU. This activity is significantly higher than the control LDH activity of 247.10 +/- 19.0 IU (p-value is less than 0.05). The mean serum LDH activity among female patients was 634.0 +/- 35.0 IU, which is a relatively higher activity compared to the control LDH activity of 247.10 +/- 19.0 IU (p-value is less than 0.05). CONCLUSION: The combination of acute hepatocellular injury and red cell haemolysis induced by the invading merozoites may account for the increase in serum LDH activity during this infection. Therefore serum LDH activity is a potentially valuable enzymatic marker of acute, uncomplicated P. falciparum malaria infection, especially in the absence of other complicating diseases known to be associated with the above normal serum LDH activities.

Dental fluorosis and fluoride mapping in Langtang town, Nigeria.

This study is aimed at measuring the fluoride concentrations of different water supplies in a Nigerian community known to have endemic fluorosis. This is with the view of mapping out a pattern and to investigate the relationship of this pattern with the distribution of dental fluorosis among residents of the community. A representative sample of 475 persons selected on the basis of criteria described in an earlier publication, constituted the study subjects. Clinical examination were carried out after obtaining sociodemographic information from the subjects. Analyses of fluoride concentrations in 136 water samples revealed, in general the highest levels in stream water range: 2.39-3.96 ppm, followed by wells (range: 1.26-2.82 ppm) and the least in pipe-borne water (range: 0.5-0.97 ppm). In plotting specific fluoride readings from the different identified sources on the geographical map of the study area, a distinctive pattern emerged. High fluoride readings were generally in the highland areas from which rivers and streams took origin. Approximately 50% of the town was supplied with water containing fluoride above the optimum. As reported in the earlier publication, the prevalence of dental fluorosis was found to be 26.1%. The age specific prevalence rate indicated the highest occurrence rate among those aged 10-19 years. Six of the participating children had involvement of deciduous teeth. Even though no correlation was established between dental fluorosis and sex on one hand and fluorosis and ethnicity on the other, there was a markedly significant association between fluorosis and source of drinking water (P < 0.05). Those who drank from streams appeared more likely to have fluorosis. It was concluded that though other sources of fluoride ingestion have been documented, it appeared that water may play a very significant role in the aetiology of fluorosis in this community.

Glutathione deficiency does not elevate susceptibility of bacteria to the mutagenicity of chlorinated humic acids.

1. Rat liver 9,000 g supernatant protected against the mutagenic effect of chlorinated hydrophilic macromolecular humic acids (CHMA) in Salmonella typhimurium strain TA100. 2. Protection against mutagenicity of CHMA was mediated by glutathione and was partially dependent on glutathione S-transferase activity. 3. In contrast to the above findings, CHMA showed lower mutagenicity in Salmonella typhimurium and Escherichia coli strains of bacteria that are deficient in glutathione compared to their mutagenicity in parental (glutathione-rich) bacterial strains. 4. Glutathione-deficient cells do not provide test systems with elevated sensitivity for the detection of mutagenic chlorinated humic substances.

The goitre-soil-water-diet relationship: case study in Plateau State, Nigeria.

The effect of drinking water, soil mineral composition and nutrition on the incidence of goitre in Plateau State, Nigeria, was studied. The study shows that the water used for drinking and cooking in the goitrous areas is low in iodine content and trihalomethanes, but high in mineral content, including calcium, magnesium, nitrate, chloride and total hardness. The water is also high in organic, inorganic and bacterial pollution content. Soil pH in the goitrous area is acidic and mineral composition follows the same pattern indicated from water analysis. Soil iodine content is very low. Diet in the goitrous zone consists mostly of foods with high cyanogenic glycoside and low iodide. The ratios of iodide to thiocyanate in urine excreted by subjects from both goitrous and non-goitrous areas show a strong correlation with goitre endemia. These studies exemplify goitre as having multicausal factors--lack/deficiency of iodine, familial or genetic tendencies, diet, and pollutants which serve as goitrogens.

Distance changes at the regulatory and catalytic sites on Escherichia coli glutamine synthetase: a spin label study on the effect of substrate(s) binding.

A spin-labeled ATP analogue, 2,2,6,6-tetramethylpiperidine-1-oxyl adenosine triphosphatase (Tempo-ATP) is used to adenylate Escherichia coli glutamine synthetase (L-glutamine: ammonia ligase (ADP-forming), EC 6.3.1.2). The Tempo adenylylated glutamine synthetase (Tempo-GS) exhibits similar catalytic properties, pH profile and inhibitor susceptibility as those of glutamine synthetase adenylylated with normal ATP. Using the spin label on the enzyme as a probe and employing the spin-spin interactions between the label probe and paramagnetic Mn2+, the distances from the nitroxyl moiety of the covalently bound Tempo-AMP to the two Mn2+ binding sites, n1 and n2 were determined. The n1 site is the structural site and n2 is located at the catalytic site. The distances from Mn2+ at n1 and n2 sites to the nitroxyl radical are 19 and 16 A, respectively. Binding of the substrate, L-Glu, causes a protein conformational change which is reflected by the reduction of approximately 2 A for the n1 to Tempo-AMP distance and lengthening of approximately 2 A for the n2 to the Tempo-AMP distance. Addition of ATP to the Tempo-GS/L-Glu complex increases the distance between n1 and Tempo-AMP, and n2 and Tempo-AMP by 4 and 3 A, respectively.

Spin-labeled analogues of ATP, ADP and AMP: substitutes for normal nucleotides in biochemical systems.

The different roles and effectiveness of adenosine monophosphate, diphosphate and triphosphate labeled at the 6 position of the purine ring with 2,2,6,6-tetramethylpiperidine-1-oxyl in reactions catalyzed by Escherichia coli glutamine synthetase (GS) have been investigated. Our results show that the spin-labeled ATP (Tempo-ATP) serves as a substrate in the glutamine synthesis reaction and in the adenylation of E. coli glutamine synthetase catalyzed by ATP: glutamine adenylyl transferase (ATase) with essentially the same effectiveness as normal ATP. In another reaction (gamma-glutamyltransferase), Tempo ADP serves as an effector with a Km of 9.4 . 10(-8) M compared to 1.2 . 10(-8) M for the normal ADP, while covalently bonded Tempo-AMP serves as a modifier on the catalytic properties of E. coli glutamine synthetase just as the covalently bonded normal AMP does. The dissociation constants between the labeled nucleotides, Mn2+, Mg2+ and Ca2+ are in the same order of magnitude as the binding constants for those cations and the corresponding normal nucleotides. Our findings indicate that the spin-labeled nucleotides are good substitutes for the normal nucleotides in the biochemical systems studied.

Catalytic cycle of the biosynthetic reaction catalyzed by adenylylated glutamine synthetase from Escherichia coli.

The covalently attached AMP moiety of adenylylated glutamine synthetase from Escherichia coli has been replaced by its fluorescent analog, 2-aza-1,N6-etheno-AMP (aza-epsilon-AMP). The modified glutamine synthetase (aza-epsilon-GS) exhibits divalent cation requirement (Mn2+, rather than Mg2+), pH profile, Vmax, and Km similar to those of naturally adenylylated glutamine synthetase. Whereas naturally adenylylated glutamine synthetase exhibits only negligible fluorescence changes upon the binding of substrates, aza-epsilon-GS exhibits large fluorescence changes. The fluorescence changes have been used by means of a stopped flow technique to reveal the involvement of five fluorometrically distinct intermediates in the catalytic cycle for the biosynthesis of glutamine catalyzed by the adenylylated glutamine synthetase. The mechanism is very similar to that previously established for the unadenylylated enzyme, using intrinsic tryptophan fluorescence. Substrates bind via a rapid equilibrium random mechanism, but the reaction proceeds in a stepwise manner. The formation of an enzyme-bound intermediate (probably gamma-glutamyl phosphate + ADP) from ATP and L-glutamate is the rate-limiting step, with the subsequent reaction of the enzyme-bound intermediate occurring very rapidly. The success in elucidating this complex mechanism is due largely to the vastly different amplitudes of the fluorescence changes at the two excitation maxima (300 nm and 360 nm) of the aza-epsilon-AMP moiety which accompany the formation of the various intermediates.

Fluorometric studies of aza-epsilon-adenylylated glutamine synthetase from Escherichia coli.

Glutamine synthetase in Escherichia coli is regulated by adenylation and deadenylation reactions. The adenylation reaction converts the divalent cation requirement of the enzyme from Mg2+ to Mn2+. Previously, the catalytic action of unadenylated glutamine synthetase was elucidated by monitoring the intrinsic tryptophan fluorescence change accompanying substrate binding. However, due to the lack of changes in the tryptophan fluorescence, a similar study could not be done with the adenylated enzyme. In this study, therefore, an extrinsic fluor is introduced into the adenylated glutamine synthetase by adenylating the enzyme with 2-aza-1,N6-ethenoadenosine triphosphate, a fluorescent analog of ATP. The modified enzyme (aza-epsilon-glutamine synthetase) exhibits catalytic and kinetic properties similar to those of the naturally adenylated enzyme. The results of fluorometric studies on this aza-epsilon-glutamine synthetase indicated that L-glutamate and ATP bind to both Mn2+ and Mg2+ forms of the enzyme in a random order, but only the Mn2+ form is capable of forming a highly reactive enzyme-bound intermediate which is a prerequisite for the reaction with NH4+ to form products. The extrinsic fluorescence changes are also used to determine the binding constants of various substrates and inhibitors of both the biosynthetic and gamma-glutamyl transfer reactions.