Showing papers by "Mahidol University published in 1992"
296 citations
TL;DR: The nucleotide and amino acid sequence homologies of the four HCV-T clones showed that the HCV -T type could be classified into two genotypes,HCV-Ta and HCv-Tb.
174 citations
TL;DR: Both released and wild females showed a low frequency of sugar feeding in nature; both small-bodied and large-bodied individuals failed to sugar feed significantly; Presumably, the nonutilization of plant sugar as an energy source increases the frequency of blood feeding and, therefore, the vectorial capacity of Ae.
Abstract: Female Aedes aegypti (L.) of two different body sizes and provided with different diets (20% sucrose, water only, or 20% sucrose + human blood) were marked and released together in a rural Thai village. Recaptured marked and unmarked (wild) adults were tested for fructose by the cold-anthrone reaction. Both released and wild females showed a low frequency of sugar feeding in nature; both small-bodied and large-bodied individuals failed to sugar feed significantly. Marked females released with sugar in their crop utilized this energy source over the following 2-3 d but failed to replenish it. In contrast, about one-third of wild, resting males showed evidence of recent sugar feeding. This indicated that the absence of plant sugar in females was not caused by a shortage of nectar sources in this rural domestic environment. Presumably, the nonutilization of plant sugar as an energy source increases the frequency of blood feeding and, therefore, the vectorial capacity of Ae. aegypti.
155 citations
TL;DR: The combination of artesunate followed by mefloquine is highly effective and well tolerated in patients with acute, uncomplicated falciparum malaria in Thailand.
150 citations
TL;DR: Although vomiting < 1 h after treatment was more likely in young children, children overall tolerated mefloquine better than adults, and men better than women, and the optimum treatment dose of meFLoquine in this area is 25 mg/kg.
Abstract: The therapeutic efficacy and toxicity of a high-dose (25 mg/kg) mefloquine regimen (M25) and the currently recommended regimen of 15 mg/kg (M15) were compared in 199 patients with acute falciparum malaria in an area with deteriorating multidrug resistance on the Thai-Burmese border. The clinical and parasitologic responses were significantly more rapid with M25. The incidence of treatment failures by day 7-9 was 7% for M15 and 1% for M25 (P = .03) and had increased to 40% and 9%, respectively, by day 28 (P 5 days after treatment experienced subsequent recrudescence. Side effects were dose-related and included dizziness, anorexia, nausea, vomiting, and fatigue. Although vomiting < 1 h after treatment was more likely in young children, children overall tolerated mefloquine better than adults, and men better than women. The optimum treatment dose of mefloquine in this area is 25 mg/kg.
113 citations
TL;DR: A simple mathematical model describing the changes in circulating and sequestered parasite numbers during acute falciparum malaria shows large fluctuations in parasitaemia over short periods related to synchronous sequestration and subsequent reinvasion following merogony.
Abstract: The sequestration of erythrocytes containing mature forms of Plasmodium falciparum in the microvasculature of vital organs may cause large discrepancies between the peripheral blood parasite count and the total body parasite burden in falciparum malaria Despite this, parasitaemia is widely used as an indicator of prognosis and response to treatment A simple mathematical model describing the changes in circulating and sequestered parasite numbers during acute falciparum malaria is presented The model uses two parameters only; the standard deviation (SD) of parasite age since merogony (schizogony) as as a measure of synchronicity, and a multiplication factor each 48 h asexual life cycle The model predicts that during the rising phase of the infection the ratio of circulating to sequestered parasites is dependent largely on the synchronicity of infection rather than multiplication rate, and that in synchronous infections parasitaemias will show considerable fluctuation when the mean stage of parasite development is in the second half of the asexual life cycle The model fitted well to serial parasite counts from 4 patients with acute uncomplicated falciparum malaria whose infections failed to respond to ciprofloxacin All four infections were synchronous (SD < or = 4 h), and showed large fluctuations in parasitaemia over short periods related to synchronous sequestration and subsequent reinvasion following merogony The parasite multiplication rate was determined mainly by the efficiency of merogony or merozoite invasion rather than clearance of circulating parasitized erythrocytes This suggests that the spleen is relatively inactive during the rising phase of the infection Quinine treatment did not prevent sequestration but did stop subsequent multiplication(ABSTRACT TRUNCATED AT 250 WORDS)
109 citations
102 citations
TL;DR: Pyronaridine given orally, intramuscularly or by intravenous drip is not only effective against malaria but also has low toxicity.
Abstract: Pyronaridine, a hydroxyanilino-benzonaphthyridine derivative synthesized in 1970, is a new antimalarial compound which has been in use in China for more than 10 years. The drug is highly effective against Plasmodium falciparum and P. vivax. Furthermore, it is efficacious in combatting chloroquine-resistant strains of falciparum malaria both in vitro and in vivo, in human patients. Extensive field studies involving several thousand cases have shown that pyronaridine has promising therapeutic value in the treatment of malarial infection, including chloroquine-resistant infections. Pyronaridine given orally, intramuscularly or by intravenous drip is not only effective against malaria but also has low toxicity.
94 citations
TL;DR: The technique of hospital-based collection, labelling and preservation of dead snakes brought by bitten patients is recommended when rapid assessment of a country's medically important herpetofauna is required.
Abstract: Snakes which had been killed and brought to hospital with the patients they had bitten were collected in 80 district and provincial hospitals throughout 67 provinces in Thailand in order to establish the geographical distribution and relative medical importance of the venomous species. Of the 1631 snakes collected, 1145 were venomous: Malayan pit vipers (Calloselasma rhodostoma), green pit vipers (Trimeresurus albolabris) and Russell's vipers (Daboia russelii) were the most numerous, while T. albolabris, C. rhodostoma and spitting cobras ('Naja atra') were the most widely distributed. In 22 cases, non-venomous species were mistaken for venomous ones and antivenom was used unnecessarily. The Malayan krait (Bungarus candidus) was confused with B. fasciatus in 5 cases and B. fasciatus antivenom was used inappropriately. The study extended the known ranges of most of the medically-important venomous species in Thailand. Correct identification of venomous snakes is especially important in Thailand because the locally-produced antivenoms are monospecific. The technique of hospital-based collection, labelling and preservation of dead snakes brought by bitten patients is recommended when rapid assessment of a country's medically important herpetofauna is required.
94 citations
TL;DR: Both functional indices, VRT and CIC, showed significant correlations with plasma zinc and vitamin A, respectively, and suggest that functional improvements in populations with suboptimal vitamin A and zinc nutriture can be accomplished by supplementation with less the recommended dietary allowance of these nutrients.
86 citations
TL;DR: A comparison of the sequence of the dengue-2 16681 virus with that of the candidate vaccine strain derived from it identified 53 of the 10,723 nucleotides which differed between the strains.
TL;DR: Artemether is a well tolerated and rapidly effective parenteral treatment for severe malaria in children, and would be especially valuable in areas with chloroquine-resistant P falciparum.
TL;DR: Of fourteen natural isolates of Trichoderma, no correlation was found between substrate weight loss and phenol oxidase (PO) activity in rice straw cultures and the highest PO producer from these laccase-positive strains was subjected to UV mutagenesis in order to select high and low PO activity mutants.
Abstract: Of fourteen natural isolates of Trichoderma, no correlation was found between substrate weight loss and phenol oxidase (PO) activity in rice straw cultures. The highest PO producer from these laccase-positive strains was subjected to UV mutagenesis in order to select high and low PO activity mutants. There was no significant difference in substrate weight loss for mutant strains with six times higher and six times lower PO activity than the parent strain. Nor did the enzyme activity result in decreased growth inhibition by inhibitory phenolic compounds. PO enzyme from the parent Trichoderma and one of its high-PO-activity mutants was subsequently purified by ethanol precipitation from liquid cultures optimized by supplementation with copper sulphate and cycloheximide. Protein staining and activity staining of disc electrophoresis gels showed that only one PO enzyme of approximately 71 000 Da was produced. The enzyme could be defined as a laccase (benzenediol: oxygen oxidoreductase E.C. 1.10.3.2) because it catalysed the oxidation of syringaldazine and p-phenylenediamine in the absence of hydrogen peroxide, and because it was inhibited by cetyltrimethylammonium because but not by cinnamic acid. No specific in-vivo function could be assigned to this enzyme.
TL;DR: It is concluded that changes in pyrimethamine resistance of malaria parasites may arise in at least 2 ways: (1) by structural changes in the DHFR domain of the DH FR-TS gene (as previously found by other workers); (2) by other changes, possibly affecting the expression of theDHFR-TS genes.
TL;DR: An extremely halophilic archaeobacterium, strain ORE, was isolated from traditionally fermented Thai fish sauce, which has a concentration of 4·4–5·1 M NaCl, and produced salt‐stable extracellular proteases which are likely to be important in the fermentation process.
Abstract: An extremely halophilic archaeobacterium (halobacterium), strain ORE, was isolated from traditionally fermented Thai fish sauce (nam pla) which has a concentration of 4.4−5.1 M NaCl. Polar liquid analysis and DBA hybridization revealed that it was a representative of the species Halobacterium salinarium. In common with many other strains of Halobacterium salinarium this organism produces salt-stable extracellular proteases which are likely to be important in the fermentation process
TL;DR: The peritoneum appears to be intact as if the problem was an infected haematoma which is an unusual cause of wound disruption in the editor's experience; yet the authors encountered 15 cases in 19 months, and quoted no case of the complete wound dehiscence referred to above.
Abstract: The usefulness of honey application as an alternative method of managing abdominal wound disruption was assessed. Fifteen patients whose wound disrupted after Caesarean section were treated with honey application and wound approximation by micropore tape instead of the traditional method of wound dressing with subsequent resuturing. We achieved excellent results in all the cases with complete healing within 2 weeks. Honey application is inexpensive, effective and avoids the need to resuture which also requires general anaesthesia.
TL;DR: Oral artemether can be considered as an alternative drug for multiple-drug-resistant falciparum malaria with a significantly faster parasite clearance time than mefloquine, and a significantly better cure rate with fewer episodes of dizziness and vomiting.
Journal Article•
TL;DR: Coagulation factors V, VII, and IX were the most sensitive parameters in the expression of coagulation defects and most coagulated abnormalities were due to liver involvement, however, 2 of 20 complicated cases of P. falciparum showed evidence of disseminated intravascular coagulations (DIC).
Abstract: One hundred and twenty-six patients with malaria (30 cases of P. vivax and 96 cases of P. falciparum) were studied for evidence of hematological coagulation and fibrinolysis abnormalities. Anemia associated with malaria was observed only in P. falciparum infections and there was no correlation between the degree of anemia and the percentage of parasitemia. Decreased hematocrit levels were found to be statistically significant in P. vivax infected patients (P greater than 0.05). Thrombocytopenia was observed in both P. vivax and P. falciparum malaria patients (P less than 0.001) and correlated with the degree of parasitemia (r = 0.974). Plasmin activity was normal in P. vivax malarial patients but it was significantly increased in patients with a P. falciparum of more than 5 per cent parasitemia. Coagulation profiles showed normal PT, aPTT, and TT in P. vivax infected patients while prolonged PT and aPTT were observed in P. falciparum infection which correlated with the degree of parasitemia (r = 0.0992). Coagulation factors V, VII, and IX were the most sensitive parameters in the expression of coagulation defects and most coagulation abnormalities were due to liver involvement. However, 2 of 20 complicated cases of P. falciparum showed evidence of disseminated intravascular coagulation (DIC).
TL;DR: It seems unlikely that the concurrent administration of mefloquine, or other antimalarials, with primaquine will lead to appreciably altered disposition, and the dependency of metabolite formation on NADPH indicates that cytochrome P450 isozyme(s) catalysed metabolite production.
Journal Article•
TL;DR: This report reviews work carried out over the past decades at the Hospital for Tropical Diseases, Bangkok, which monitors patients from many areas, including the Thai-Cambodian border, which harbors the world's most severe multi-drug resistant Plasmodium falciparum.
Abstract: Drug resistance of malaria parasites is a major problem confronting efforts to treat and control malaria. Starting with chloroquine, the emergence of resistance to other drugs has led to multi-drug resistance patterns that pose increasing threats for the future. This report reviews work carried out over the past decades at the Hospital for Tropical Diseases, Bangkok, which monitors patients from many areas, including the Thai-Cambodian border, which harbors the world's most severe multi-drug resistant Plasmodium falciparum.
TL;DR: Three patterns of TNF plasma concentrations were evident: relatively constant values between 100 and 500 pg/ml, high admission concentrations associated with early death, and an apparent pulse release after treatment, with peak values greater than 1000 pg/ML, which then declined with a mean (SD) apparent half-time of 131 (50) min.
Abstract: Plasma concentrations of the cytokine tumor necrosis factor (TNF) were measured serially in 91 patients suspected of having septicemic melioidosis. This was confirmed in 55. TNF was detectable in admission plasma (TNF0) in 3 of 15 survivors of septicemic melioidosis and 21 of 26 fatal cases (P less than .001). The median (range) TNF0 concentration in melioidosis patients who died was 96 (1-4774) pg/ml, and the median time to death was 25 (5-672) h. TNF0 was inversely correlated with the lowest mean arterial pressure in the succeeding 12 h (Spearman's rank correlation coefficient = .67, 2P less than .001). Three patterns of TNF plasma concentrations were evident: relatively constant values between 100 and 500 pg/ml (n = 7), high admission concentrations (greater than 1000 pg/ml) associated with early death (n = 4), and an apparent pulse release after treatment, with peak values greater than 1000 pg/ml, which then declined with a mean (SD) apparent half-time of 131 (50) min (n = 8). Further studies are necessary to determine whether TNF contributes to lethality in melioidosis.
TL;DR: The results suggest that sequential treatment with artesunate followed by mefloquine is effective and well-tolerated in patients with recrudescent falciparum malaria.
Abstract: A sequential combination of artesunate followed by mefloquine was evaluated prospectively in 24 patients with acute recrudescent falciparum malaria. The sequential combination was used to minimize possible side effects and to take advantage of the ability of artesunate to rapidly clear parasitemia and the prolonged effect of mefloquine to clear residual parasites. All patients had experienced one or more treatment failures with one or more courses of the following drugs (administered alone or in combination): quinine, tetracycline, mefloquine, artesunate, and sulfadoxine/pyrimethamine. Sequential treatment with artesunate (600 mg over five days) followed by mefloquine (750 mg and 500 mg six hours apart) cured all 24 patients. Each patient was followed for 28 days and 10 were observed for at least 35 days without clinical or parasitologic evidence of recrudescence. Fever and parasite clearance times after treatment with the sequential combination were 32.8 +/- 19.3 hr (mean +/- SD) and 40.0 +/- 16.2 hr, respectively. Susceptibility testing of selected parasite isolates indicated that all of the isolates tested were resistant to one or more antimalarial drugs. These results suggest that sequential treatment with artesunate followed by mefloquine is effective and well-tolerated in patients with recrudescent falciparum malaria.
Journal Article•
TL;DR: Pulmonary thromboembolic lesions were found in 24 of 58 patients with beta-thalassemia/hemoglobin E disease (beta-thal/HbE), including whole lungs from five, 13 patients with hemoglobin H disease (HbH), and eight patients withBeta-thalsemia major (beta) including whole lung from one, with the incidence increasing with age.
Abstract: Chronic pulmonary thromboembolism plays an important role in cardiac failure which is a major cause of death in thalassemic patients over 20 years of age. This report is a study of autopsy lung tissue from 58 patients with beta-thalassemia/hemoglobin E disease (beta-thal/HbE), including whole lungs from five, 13 patients with hemoglobin H disease (HbH), and eight patients with beta-thalassemia major (beta-thal) including whole lung from one. Pulmonary thromboembolic lesions were found in 24 of 58 (41%) patients with beta-thal/HbE, of which 21 of 39 (54%) were splenectomized patients and 3 of 19 (16%) were nonsplenectomized patients, with the incidence increasing with age. Lung maps showed the greatest number of lesions in the lingula, right middle lobe, and anterior segments of both upper lobes. Pulmonary thromboembolic lesions were also found in one of 13 HbH patients and one of 8 beta-thal patients, both splenectomized. Eight of the 27 patients with these lesions had right ventricular and 14 biventricular hypertrophy, reflecting the deleterious effect of such lesions. Possible causative factors are discussed.
TL;DR: Red mud has been activated by dissolution in hydrochloric acid and reprecipitation with ammonia and has been evaluated as a catalyst for the hydrogenation of naphthalene, phenanthrene and pyrene as discussed by the authors.
TL;DR: An acoustic perceptual investigation of the five lexical tones of Thai was conducted to evaluate the nature of tonal disruption in patients with unilateral lesions in the left and right hemisphere, and found that left hemisphere nonfluent speakers signaled and tonal contrasts at a lower level of proficiency.
TL;DR: Pregnant women with unfavorable cervix and well established gestational age of at least 42 weeks were selected for management by either antepartum fetal testing or prostaglandin gel induction of labor and the data show that there is no particular advantage in letting the pregnancy go beyond 42 completed weeks of gestation.
TL;DR: The data do not support a role for tissue edema in the pathogenesis of cerebral malaria but reveal an association between markers of disease severity and a generalized increase in systemic capillary permeability.
Abstract: Capillary permeability was investigated in 32 Thai patients aged 14-49 years who had acute falciparum malaria with use of three distinct techniques: quantitation of the urinary albumin/creatinine ratio (ACR), estimation of the transcapillary escape rate of radiolabeled albumin (TER), and retinal photography/fluorescein angiography. Fourteen patients had uncomplicated infections and 18 were severe cases. The severely ill patients had significantly higher ACRs (median, 4.8 mg/mmol; 95% confidence limits, 2.4-19.9 mg/mmol) and TERs (median, 8.3%/h; 95% confidence limits, 6.2-13.2%/h) than the uncomplicated cases (ACR: median, 2.1 mg/mmol; 95% confidence limits, 6.2-13.2%/h) than the uncomplicated cases (ACR: median, 2.1 mg/mmol; 95% confidence limits, 1.0-8.8 mg/mmol; TER: median, 5.9%/h; 95% confidence limits, 3.8-10.6%/h; P = .014 and .042). Both variables were significantly associated with biochemical indices of disease severity including total serum bilirubin levels (rs greater than or equal to 0.398, P less than .025 in each case), but there were no significant differences between ACRs and TERs among comatose and noncomatose patients with severe infections (P greater than or equal to .08). Retinopathy (hemorrhages, cotton-wool spots, capillary nonperfusion, and/or extravasation of fluorescein) was found in eight severely ill patients and in two uncomplicated cases. Fluorescein leakage was evident in six patients. Although fluorescein leakage had the strongest parametric correlation with the presence of coma relative to both ACR and TER in the full patient series (r = 0.58, P less than .01), multiple linear regression analysis indicated that concentrations of plasma lactate (t = 2.998, P = .006) and serum creatinine (t = 2.200, P = .036) were the factors responsible for this association. These data do not support a role for tissue edema in the pathogenesis of cerebral malaria but reveal an association between markers of disease severity and a generalized increase in systemic capillary permeability.
Journal Article•
TL;DR: It is concluded that artemether can be considered as an alternative antimalarial for multiple drug resistant falciparum malaria, however, the cure rate of severe malaria in this study is not considered satisfactory in areas with multiple drugresistant falcIParum Malaria.
Abstract: Artemether has the potential to be an alternative antimalarial for multiple drug resistant falciparum malaria. However, it has been associated with high recrudescent rates which may be due to incorrect dosage regimens. The dosage regimens are varied from country to contry. We have carried out a comparative study of two dosage regimens, ie 480 mg and 600 mg total dose given over 5 days in uncomplicated and severe falciparum malaria. 167 patients were included in the study, 61 with acute uncomplicated falciparum malaria and 106 with severe malaria. All patients showed a good initial response. The difference in total dose had no effect on the parasite or fever clearance time (PCT or FCT). However, the severity of the disease did have some influence of these times. The PCT and FCT from either regimen of uncomplicated malaria were significantly faster than those of severe malaria (p < 0.005 and = 0.05, respectively). The cure rate seems to have some correlation with the amount of drug given and severity of the disease. The cure rates in uncomplicated malaria were 84 and 92%, respectively, for 480 mg and 600 mg. In severe malaria the cure rates dropped to 65 and 76%, respectively, for 480 and 600 mg. We conclude that artemether can be considered as an alternative antimalarial for multiple drug resistant falciparum malaria. However, the cure rate of severe falciparum malaria in this study is not considered satisfactory in areas with multiple drug resistant falciparum malaria. Further studies are needed to assess the curative efficacy with different dosage regimens.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Mixtures of chromosomal forms A, B, C and D in natural populations of Anopheles dirus Peyton & Harrison sensu lato in Thailand show significant positive values of Wright's fixation index for six enzyme‐electromorph loci, which supports the hypothesis that the chromosomal/electrophoretic forms C, D, A and D represent four distinct biological species within the An.dirus complex.
Abstract: . Mixtures of chromosomal forms A, B, C and D in natural populations of Anopheles dirus Peyton & Harrison sensu lato in Thailand show significant positive values of Wright's fixation index for six enzyme-electromorph loci. The mean value of FIS over all loci was found to be +0.28 (SD 0.02), with a range of +0.57 (Odh) to +0.10 (Idh-2). Partitioning electromorph data for the chromosomal forms reduces the mean FIS to 0.03 (SD 0.01), which suggests that positive assortative mating is a characteristic of each form. This supports the hypothesis that the chromosomal/electrophoretic forms A, B, C and D represent four distinct biological species within the An.dirus complex.
An example is given of the use of enzyme electromorphs as a means of vector identification during a malaria entomological field study involving a mixture of An.dirus species A and D. Electromorph identifications of 323 sp. A and 161 sp. D were more than 98% correct when cross-referenced to specific DNA probes.
Journal Article•
TL;DR: It is suggested that a non-immunologically mediated mechanism is involved in the pathogenesis of thrombocytopenia in malaria.
Abstract: The relationship between platelet counts and platelet bound (direct) or platelet directed (indirect) serum antibody concentrations was studied in 17 patients with Plasmodium falciparum malaria and 12 patients with P. vivax malaria. Platelet counts rose with recovery from infection from 196 +/- 84 x 10(9)/l (mean +/- SD) and 195 +/- 34 x 10(9)/l to 319 +/- 99 and 283 +/- 62 x 10(9)/l respectively (p less than 0.002), but there was no relationship between either absolute platelet count or changes in counts and either indirect or direct platelet antibody levels. These findings suggest that a non-immunologically mediated mechanism is involved in the pathogenesis of thrombocytopenia in malaria.