Studies on the cobra neurotoxin inhibiting activity in an extract of Curcuma sp. (Zingiberaceae) rhizome.

A study was carried on the mode of action and some properties of a cobra neurotoxin inhibitor found in the extract of Curcuma sp. (Zingiberaceae). When the principal postsynaptic neurotoxin (STX) of the Thai cobra (Naja naja siamensis) was mixed with an aqueous extract of Curcuma sp. rhizome, the STX was inactivated as tested in mice or in vitro using a rat hemidiaphragm preparation. The 'neurotoxin inhibitor' ('NTxI') was found only in the water insoluble fraction of the rhizome extract. Using radioactively labeled neurotoxins, 125I-STX and 3H-STX, it was demonstrated that the neurotoxin did not form a stable complex with the 'NTxI'; the inactivated neurotoxin remained in the supernatant of the reaction mixture. After inactivation by 'NTxI', the STX exhibited an unchanged molecular weight as judged by SDS-polyacrylamide gel electrophoresis and an unchanged isoelectric point in isoelectric focusing. Extraction of the Curcuma sp. rhizome with at least 0.2% Triton X-100 resulted in solubilization of a component capable of forming a soluble and stable complex with 3H-STX. By column chromatography on Sephadex G-200 in the presence of 0.1% Triton X-100, the toxin-binding compound was shown to have a molecular weight of about 150 kDa. This 150 kDa component was obtained by Triton extraction of the water-insoluble fraction, and much less from the water soluble fraction, of Curcuma sp. rhizome. It did not possess any carbohydrate side-chain capable of binding the lectin Concanavalin A. The time course of the 150 kDa-3H-STX complex formation was extremely slow (approx 22 hours).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoassays of amphetamines: immunogen structure vs antibody specificity.

Various immunoassays have been developed for the detection of amphetamines. These have varying degrees of cross-reactivity to other drug and food components. Information on the immunogen structures used, and the specificities of the antibodies obtained, have allowed formulation of a "structure-specificity" pattern delineated on the basis of immunochemistry and stereochemistry. The 'structure-specificity' relationship should be useful to future developments of these immunoassays. Specifically, immunoassays intended to detect either amphetamine or methamphetamine with minimal cross-reaction, should employ immunogens with amphetamine (or methamphetamine) derivatized via the para position of the phenyl ring. Such assays should show minimal cross-reaction with other secondary (or tertiary) amines but should strongly cross-react with phenyl ring substituted analogs. On the other hand, assays intended for detection of both amphetamine and methamphetamine should employ amphetamine (rather than methamphetamine) derivatized via its amino group as an immunogen. Such assays should show minimal cross-reaction with other tertiary amines and phenyl-substituted amphetamine/methamphetamine.

Studies on the 52 kDa antigen of Salmonella typhi: physicochemical stability, purification by affinity chromatography and immunochemical specificity.

The 52 kDa specific protein antigen of Salmonella typhi, as identified by monoclonal antibodies (Ekpo et al. 1990) has been studied with respect to its physicochemical stability, purification by affinity chromatography and immunochemical specificity. It was found that the 52 kDa protein was degraded into smaller antigenic fragments of MW 30-51 kDa when treated with acetone, ethanol, sodium thiocyanate, 0.3M sodium chloride and Veronal and Tris buffers. The exact chemical nature of the degradation of the protein under these conditions is not known but digestion by conventional proteases and dissociation of the non-covalent subunit type have been ruled out. It is proposed that the degradation may be the result of yet unidentified enzyme(s) which become activated by various physical or chemical treatments. Affinity chromatography using a specific monoclonal antibody has been carried out in an attempt to purify the 52 kDa protein. The binding of S. typhi protein to the column was saturable at 65.6 microgram protein/ml gel. The amount of S. typhi protein adsorbed on the column was 0.51% of the total sonicated cell protein. SDS-PAGE of the immunoadsorbent purified protein revealed bands at Mr 15-58 kDa, indicating that the protein obtained had been severely degraded. However, Western blot of the purified protein stained with a specific monoclonal antibody and with rabbit polyclonal antibody against S. typhi showed striking similarity, indicating that the protein obtained was close to immunochemical purity. The 52 kDa protein purified by affinity adsorbent was used as an antigen for the detection of specific IgM in sera of patients. It was shown that sera of patients infected with S. typhi as well as those infected with other bacteria, contained specific IgM against the 52 kDa protein. Thus, it appears that the 52 kDa protein contains species specific as well as cross-reacting epitopes. The possible development of specific diagnosis of S. typhi based on the present experimental results in discussed.

Immunodiagnosis of snake venom poisoning.

Uncertainty as to the species diagnosis remains a serious problem in the management of snake venom poisoning. This is particularly so in areas inhabited by numerous species, the venoms of which elicit similar pharmacological effects and clinical symptoms and against which para-specific cross-neutralizing antivenom is not available. Attempts have been made to eliminate some of this ambiguity through the development of various immunodiagnostic tests. Tests based on ELISA are sensitive, specific and even quantitative and adaptable to field application. In the development of diagnostic tests for use in developing countries, however, practical consideration must be given to speed, cost, simplicity in terms of equipment and expertise, and stability to the climate and storage conditions. This may dictate further modification or selection of more suitable alternative methodologies. Furthermore, the test may have to allow more flexibility in accommodating local species distributions and to address probable complications of heterophile antibodies in test samples from rural people.

Serum folate and folic acid binding proteins in iron deficiency anaemia.

Serum and red cell folate and folic acid binding protein (FABP) concentrations were determined on 20 iron deficiency anaemic children of both sexes aged 6--12 years. All cases had haemoglobin level less than 12 gm% or haematocrit less than 36% with low serum iron and elevated unsaturated iron binding capacity. Serum folate levels in the anaemic group was not significantly different from that of normal subjects while red cell folate level was significantly lower in the anaemic group. However, all cases had red cell folate levels higher than 100 ng/ml. There was a direct relationship between the haemoglobin concentration and serum folate level. Serum FABP level in the anaemic group was found to be significantly higher than that of normal subjects and showed no correlation with haemoglobin, haematocrit, serum or red cell folate levels. The significance of elevated serum FABP was discussed.

Vitamin B12 and vitamin B12 binding proteins in iron deficiency anaemia.

Vitamin B12 and vitamin B12 binding proteins were determined in 20 patients with iron deficiency anaemia who showed low haemoglobin, haematocrit, serum iron levels and hypochromic microcytic red blood cells. The serum vitamin B12 levels in these patients were significantly lower than that of the normal subjects. Nine of 20 patients had serum vitamin B12 less than 350 pg/ml. There was a significant increase in serum UBBC and TBBC levels in patient group and 9 of 20 patients had higher UBBC values than those of the normal subjects. The absolute values of TCI and TCII increased significantly while TCIII was within the normal limit even though the percentage of UBBC were not different from that of the normal subjects.

The absence of antagonism between extracts of Clinacanthus nutans Burm. and Naja naja siamensis venom.

Clinacanthus nutans Burm, a herb reputed in Thailand and Malaysia to be "snakebite antidote" has been tested in vitro and in vivo for antivenin activity. The aqueous extract of C. nutans leaves has been found to have no effect on the inhibition of neuromuscular transmission produced by purified Naja naja siamensis neurotoxin in isolated rat phrenic-nerve diaphragm preparations. The extract of C. nutans, when given orally or intraperitoneally, are ineffective in prolonging the survival time of experimental mice receiving lethal doses of N.n. siamensis crude venom. Oral administrations of the herb extracts pretreated with alpha-amylase or beta-amylase also fail to protect the animal. It is concluded that the extract of C. nutans can not antagonize the action of cobra venom.

Juvenile rheumatic fever and rheumatic heart disease at Ramathibodi Hospital, Thailand.

One hundred consecutive cases of rheumatic fever and rheumatic heart disease who were seen at Department of Pediatrics. Ramathibodi Hospital were reviewed. Particular attention was given to the pattern and the outcome of the cardiac status of the patients. The high incidence of severe carditis and tight mitral stenosis was similar to most reports from other developing countries. There was a poor prognosis for the cardiac status of those who came late, had more than valvular lesions, were in congestive heart failure, or had preexisting heart disease and atrial fibrillation. In spite of this, 6 patients had no evidence of heart disease after being followed up for less than 5 years.