Effect of different Thai traditional processing of various hot chili peppers on urethane-induced somatic mutation and recombination in Drosophila melanogaster: assessment of the role of glutathione transferase activity.

Four different Thai traditional chili peppers, namely bird pepper (Capsicum frutescens), red chili spur peppers (Capsicum annuum), green bell peppers and sweet pepper (C. annuum) were investigated for their antimutagenic properties. Each chili was prepared in three formulations commonly used for chili food processing; raw paste (chili ground in water), pickled in vinegar or stir-fried in palm oil. Each sample was tested for its antimutagenic effect against urethane by using the somatic mutation and recombination of wing hair of Drosophila melanogaster as an indicator. Three-day-old larvae, trans-heterozygous for two genetic markers, multiple wing hairs mwh and orrigon (ORR;flr3), were exposed to urethane alone or in combination with each chili formulation. The various processing methods for chilies differentially extracted the antimutagenic chili components. The specific chili as well as the method of processing influenced the observed antimutagenic properties against urethane. This suggested each chili contains a unique complex mixture of many antimutagens. Co-treatment and pre-treatment experiments showed that both direct and indirect protective mechanisms are involved in an 'activation' process to give antimutagenesis effects. An association between antigenotoxicity and glutathione transferase activity could not be established.

Analysis of polymorphism of the interleukin-6 gene in Thai subjects with osteoporosis.

Osteoporosis is the imbalance between bone formation by osteoblast and bone resorption by osteoclast. The genetic factors play an important role in determining bone mass and several genes probably act as regulators of this process. Interkeukin-6 (IL-6) is one of the candidate genes to regulate bone density, since IL-6 has some effect on stimulation of osteoclast resorption and has been implicated in the pathogenesis of bone loss associated with estrogen deficiency. We investigated the relationship between bone mineral density (BMD) and a polymorphic AT rich repeat in the 3' flank of the IL-6 gene in 272 Thai subjects. The subjects were classified into 3 groups i.e. normal healthy control (n=95), border-line (n=112) and osteoporotic patients (n=65). Five alleles different in sizes were identified (designated a, b, c, e and f). It was observed that c/c was the most common genotype in Thais (86.76%). The other genotype frequencies were 0.74, 3.31, 8.09, 0.74 and 0.37 for a/c, b/c, c/e, c/f and b/e genotypes, respectively. The common genotype was different from the Caucasians in a previous study. These frequencies were significantly different from the Caucasians (p<0.05). There was no significant relationship between 3' flanking AT repeat of the IL-6 genotypes and the BMD values of the distal forearm that were determined by One-way ANOVA (p>0.05). Additionally, the impact of the IL-6 genotypes on risk of osteoporosis was assessed by determination of the odds ratio. The c/e genotype may be a protective factor of osteoporosis. On the contrary, the b/c and c/c genotypes were considered to be risk factors of osteoporosis.

Polymorphism of the gene encoding lipoprotein lipase in thai primary hyperlipoproteinemias.

Lipoprotein lipase (LPL) plays a central role in the clearance of very low density lipoprotein (VLDL) and chylomicrons from the circulation. It also affects the maturation of high density lipoprotein (HDL) and low density lipoprotein (LDL). LPL is an important candidate gene in determining the risk factor in metabolic disorders including primary hyperlipidemia. Our study is the first report from Thailand on the characterization of two common DNA polymorphisms, i.e Pvu II and Hind III at introns 6 and 8, respectively of the LPL gene in 94 Thai dyslipidemic subjects compared to 32 normolipidemic subjects using PCR-RFLP. It was observed that the frequencies of the cut and uncut alleles of Pvu II were 0.67 and 0.33 in normolipidemic subjects. Such frequencies were 0.64 and 0.36 in hyperlipidemic subjects. Additionally, the frequencies of the cut and uncut alleles of Hind III were found to be 0.73 and 0.27 in normolipidemic subjects. They were 0.85 and 0.15 in hyperlipidemic subjects. The allele frequencies of the Hind III but not Pvu II polymorphism in hyperlipidemic subjects were significantly different from normolipidemic subjects (p<0.05). The relation between these polymorphisms and lipid traits was not statistically significant (p>0.05).

Screening for a D9N common mutation in exon 2 of the LPL gene in Thai normolipidemic and hyperlipidemic subjects.

Lipoprotein lipase (LPL) is a multifunctional protein, playing a major role in the hydrolysis of triglyceride-rich lipoproteins. It also affects the maturation of high density lipoprotein (HDL) and low density lipoprotein (LDL). A D9N substitution is a frequent mutation found in exon 2 of the LPL gene. It is due to a G --> A transition causing a substitution of Asp by Asn at amino acid residue 9 of the protein. This mutation was screened for in 94 Thai primary dyslipidemic (46 hypercholesterolemic and 48 combined hyperlipidemic) subjects compared to 32 normal healthy subjects using PCR-RFLP. Such a mutation has not, yet, been detected in any of these Thai subjects.

Heterogeneity in patterns of malarial oocyst infections in the mosquito vector.

Oocyst prevalence and intensity have been recorded in 349 laboratory infections of Anopheles stephensi with Plasmodium berghei. Intensity and prevalence of infection are shown to be predictably related. The structure and heterogeneity in the infections has been analysed with the objective of describing the biological mechanisms by which the observed negative binomial oocyst distributions are generated. The analysis has revealed that the most likely processes lie within the population dynamic events of malaria within the mosquito, namely gametogenesis, fertilization and mortality. The distribution is similar in all Plasmodium-mosquito combinations examined so far, whether they are of laboratory (P. gallinaceum in Aedes aegypti) or field (P. vivax in An. albimanus and P. falciparum in An. gambiae s.l. and An. funestus) origin. Further we conclude that there is competition between parasites in the vector. Oocyst frequency distribution analysis shows that under natural conditions of transmission intensity, and even under the best laboratory conditions, significant numbers (> 10%) of fully susceptible mosquitoes will not be infected under conditions where the mean infection is as high as 250 oocysts. Failure to infect is not therefore an absolute indicator of refractoriness. In assessing transmission data it is shown that sample sizes should not be less than 50, and ideally 100 mosquitoes, if reliable data are to be obtained. In field it is suggested that difficulties in determining the low natural intensity of oocyst infections indicate that prevalence estimates are a useful and accessible parameter to measure.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of immunity induced by the affinity-purified 21-kilodalton zygote-ookinete surface antigen of Plasmodium berghei.

By using affinity-purified ookinete surface antigen from the rodent malaria parasite Plasmodium berghei, a transmission-blocking immunity was induced in mice. Groups of mice were immunized via different routes, with total quantities of antigen ranging from 0.5 to 40 micrograms (with or without Freund adjuvant). Vaccination by the intramuscular route with 20 micrograms of antigen in the absence of adjuvant and boosted once with the same amount of protein induced a total transmission blockade. Immunoblot analysis confirmed that immune sera invariably recognized Pbs21 antigen. The isotype and titer of the anti-Pbs21 immunoglobulin G (IgG) response was determined by enzyme-linked immunosorbent assay. The antibody isotype was predominantly IgG1. The concentration of specific anti-Pbs21 IgG reached a peak of 182.45 +/- 92.13 micrograms/ml by week 7 postimmunization and fell progressively to 38 micrograms/ml at week 34 (at which time the transmission was still inhibited by 98%).

Three non-repeated transmission blocking epitopes recognized in the 21 kD surface antigen of zygotes-ookinetes of Plasmodium berghei.

Two-site and competitive ELISA have been developed against a surface antigen of zygotes-ookinetes of Plasmodium berghei using monoclonal antibodies (MoAbs) which block transmission of the parasite to the mosquito. Three such MoAbs have been studied, each of which recognized a protein of an Mr 21 kD (Pbs21) using immunoblot techniques. The assays showed that there are at least 3 single B-cell epitopes expressed in Pbs21. One epitope recognized by MoAb 17.9 is conformation dependent and antibodies bound to it interfered with other MoAbs (12.1 and 13.1) each recognizing a different, apparently linear epitope. Glycosylation might not be relevant to the binding of any of the antibodies tested to their respective epitopes.

Ookinete antigens of Plasmodium berghei. Appearance on the zygote surface of an Mr 21 kD determinant identified by transmission-blocking monoclonal antibodies.

Zygotes and ookinetes of the rodent malaria Plasmodium berghei can be enriched 50-fold, from whole blood cultures by ammonium chloride lysis. Three monoclonal antibodies (MoAbs) raised against such enriched preparations specifically bind to a determinant of Mr 21 kD as assessed by 125I-labelled goat anti-mouse IgG probed immunoblots of Western transfers of SDS-PAGE gels. Indirect immunofluorescence indicates that the 21 kD determinant bound by specific MoAbs, whilst not detectable on gametocytes or gametes, appears on the parasite surface within 2 h of exflagellation/fertilization and increases thereafter. The three MoAbs specifically binding the 21 kD determinant block oocyst development in mosquitoes by at least 90%, as assessed either by in-vitro membrane feeds or by live feeds on passively immunized mice. These MoAbs reduce ookinete formation in vitro by between 52 and 100%. Possible mechanisms of action of these MoAbs are discussed.

Differentiation of Plasmodium falciparum clones by means of a repetitive DNA probe.

A recombinant DNA probe, pBRK1-14, was constructed by inserting a repetitive DNA fragment of 753 base pairs obtained from Plasmodium falciparum, isolate K1, into the EcoRI/PstI cloning sites of pBR322. This probe could discriminate between different parasite clones derived from a single isolate by hybridization with Southern genomic blots.

Ookinete antigens of Plasmodium berghei: a light and electron-microscope immunogold study of expression of the 21 kDa determinant recognized by a transmission-blocking antibody.

The expression of a 21 kDa transmission-blocking determinant on the malarial parasite Plasmodium berghei was studied by using the immunogold method at the light, scanning-electron and transmission-electron microscope levels. The determinant was shown to be expressed exclusively on the macrogamete and its immediate progeny the zygote, ookinete and oocyst. It is first detected on the plasmalemma two hours after the escape of the parasite from the red blood cell, reaches a maximal density on the young ookinete some ten hours later, and is still found on the oocyst after six days. The antigen is distributed evenly over the entire surface of the zygote and ookinete, but is readily shed from the parasite surface. The general applicability of the silver-enhanced immunogold method in parasitological research is emphasized.