Scopus 2001-2005
Permanent URI for this collectionhttps://repository.li.mahidol.ac.th/handle/20.500.14594/8809
Browse
Recent Submissions
Publication Metadata only Calorimetric analysis of cephalosporins using an immobilized TEM-1 β-lactamase on Ni2+Chelating Sepharose Fast Flow(2001-09-01) Ratana Lawung; Bengt Danielsson; Virapong Prachayasittikul; Leif Bülow; Lunds Universitet; Mahidol UniversityTwo β-lactamases, penicillinase type I from Bacillus cereus and TEM-1 β-lactamase from Haemophilus ducreyi, were immobilized on a Chelating Sepharose Fast Flow column loaded with Ni2+in an active form. Flow-injection analysis of β-lactams was performed by using an enzyme column reactor fitted into the enzyme thermistor. With both enzymes it was possible to monitor both penicillins and cephalosporins. Moreover, Michaelis constants of the TEM-1 β-lactamase were markedly increased upon immobilization for all substrates, especially carbenicillin, cephaloridine, and cefoperazone. © 2001 Academic Press.Publication Metadata only A comparative trial of albendazole alone versus combination of albendazole and praziquantel for treatment of Trichuris trichiura infection(2001-06-01) Chukiat Sirivichayakul; Chanathep Pojjaroen-anant; Pataraporn Wisetsing; Pornthep Chanthavanich; Rangson Praevanit; Kriengsak Limkittikul; Krisana Pengsaa; Mahidol UniversityA randomized clinical trial was conducted to compare the effectiveness of albendazole alone and albendazole combined with praziquantel in the treatment of Trichuris trichiura infection. The drug regimens consisted of single dose of albendazole 400 mg (Al, n=34), 3 days of albendazole 400 mg daily (A3, n=34), 5 days of albendazole 400 mg daily (A5, n=35), single dose of albendazole 400 mg plus praziquantel 40 mg/kg (A1P1, n=34), and 3 days of albendazole 400 mg plus praziquantel 40 mg/kg daily (A3P3, n=36). It was found that treatment with 3 or more consecutive days of albendazole with or without praziquantel resulted in a significant reduction in density of Trichuris eggs in stools while a single dose of such drug did not. Praziquantel was not shown to have synergistic or antagonistic effects with albendazole. A regimen of 400 mg of albendazole daily for 3 days was found to be the most suitable therapy for Trichuris infection.Publication Metadata only Lack of association of -308A/G TNFA promoter and 196R/M TNFR2 polymorphisms with disease severity in Thai adult malaria patients [3](2001-09-01) Hathairad Hananantachai; Jintana Patarapotikul; Sornchai Looareesuwan; Jun Ohashi; Izumi Naka; Katsushi Tokunaga; Mahidol University; University of TokyoPublication Metadata only Localization of egg-laying hormone in the gonads of a tropical abalone, Haliotis asinina linnaeus(2001-12-01) M. Chanpoo; S. Apisawetakan; A. Thongkukiatkul; C. Wanichanon; V. Linthong; M. Kruatrachue; E. S. Upatham; T. Pumthong; P. J. Hanna; P. Sobhon; Mahidol UniversityConnective tissue frameworks of the gonad of H.asinina consist of the outer gonadal capsule, flat sheets of connective tissue, called trabeculae, that extend from the former toward the inner capsules separating the gonad from the hepatopancreas. Trabeculae, thus, partition the gonad into compartments; and each trabecula acts as the axis on which growing germ cells are attached and proliferate. Each trabecula contains small capillaries in the center, surrounded by muscle cells, collagen fibers intermingled with fibroblasts, and a substantial number of granulated cells that branch extensively. Localization of abalone egg-laying hormone (aELH) was performed by immunoperoxidase technique using polyvalent antibody against recombinant aELH as a probe. Anti-aELH exhibited strong bindings, which implied the presence of aELH, to muscle cells and granulated cells within trabeculae and capsules of both male and female gonads. The cytoplasm of immature oocytes (stages 1, 2, 3) were moderately stained, while that of mature oocytes (stages 4, 5) were only weakly stained. In contrast, male germ cells were not stained.Publication Metadata only Construction of infectious dengue 2 virus cDNA clones using high copy number plasmid(2001-02-14) Rungtawan Sriburi; Poonsook Keelapang; Thaneeya Duangchinda; Sumalee Pruksakorn; Niwat Maneekarn; Prida Malasit; Nopporn Sittisombut; Chiang Mai University; Thailand National Science and Technology Development Agency; Mahidol UniversityProcedures for cloning entire dengue serotype 2 virus genome in the multiple cloning site of a commercially available high copy number plasmid are described. The 10.7 kb viral RNA genome was reverse transcribed, amplified as three overlapping DNA fragments and successively ligated into pBluescript II KS, which contains the colE1 origin of replication. When propagated at room temperature (20-25°C) under low level of antibiotic selection, the full-length recombinant plasmid was stable upon serial passages in two common Escherichia coli strains employed. Under the same culture conditions the whole dengue cDNA sequence was transferred successfully to another high copy number plasmid, pGem 3Z. Following in vitro transcription and lipofectin-mediated transfection, capped RNA transcripts derived from the plasmid initiated virus replication in C6/36 mosquito cells and BHK-21 cells within 3-4 days of transfection. Upon subsequent expansion in C6/36 cells, dengue viruses derived from the first- and eighth-plasmid passages achieved similar titers as the parent virus. They were also indistinguishable from the parent virus by the criteria of replication kinetics in mosquito and mammalian cell lines, and size and reactivity of selected viral proteins as detected with polyclonal and monoclonal antibodies. The cloning scheme and resultant recombinant plasmids based on high copy number cloning vectors allows greater flexibility in manipulation of dengue viral genome when compared with previous attempts employing low-copy number counterparts. © 2001 Elsevier Science B.V.Publication Metadata only TPA-activated transcription of the human MnSOD gene: Role of transcription factors SP-1 and Egr-1(2001-01-01) Sureerut Porntadavity; Yong Xu; Kelley Kiningham; Vivek M. Rangnekar; Daret K. St. Clair; Vivek M. Rangnekar; Sureerut Porntadavity; Virapong Prachayasitikul; University of Kentucky College of Medicine; University of Kentucky; Mahidol UniversityInduction of manganese superoxide dismutase (MnSOD) in response to oxidative stress has been well established in animals, tissues, and cell culture. However, the role of the human MnSOD (hMnSOD) promoter in stimulus-dependent activation of transcription is unknown. The hMnSOD promoter lacks both a TATA and a CAAT box but possesses several GC motifs. In a previous study, we showed that the basal promoter contains multiple Sp1 and AP-2 binding sites and that Sp1 is essential for the constitutive expression of the hMnSOD gene. In this study, we identified an Egr-1 binding site in the basal promoter of hMnSOD. We also found that the basal promoter is responsive to 12-O-tetradecanoylphorbol-13-acetate (TPA)-activated hMnSOD transcription in the human hepatocarcinoma cell line HepG2. The contributions of these binding sites and the roles of the transcription factors Egr-1, AP-2, and Sp1 in the activation of hMnSOD transcription by TPA were investigated by site-directed mutation analysis, Western blotting, and overexpression of transcription factors. The results showed that Sp1 plays a positive role for both basal and TPA-activated hMnSOD transcription, whereas overexpression of Egr-1 has a negative role in the basal promoter activity without any effect on TPA-mediated activation of hMnSOD transcription.Publication Metadata only The activation of platelet aggregation by human cholangiocarcinoma cells is mediated through thrombin receptor(2001-12-01) Pravit Akarasereenont; Sirikul Chotewuttakorn; Tipsuchon Aiamsa-Ard; Athiwat Thaworn; Mahidol UniversityTumor cell induced platelet aggregation (TCIPA) played an importance role in early state of thrombosis in cancer patients. In addition, TCIPA was recognized as one important step in metastatic cascade. Cholangiocarcinoma, one of the most common cancers in the north-eastern part of Thailand, associated with thrombosis was reported. The authors investigated the effects of Cholangiocarcinoma cells on platelet function as measured by platelet aggregation. Primary human chlolangiocarcinoma (HuCCA) cells were established in our laboratory. Cells were cultured as standard techniques and grown to confluence until used, after which cells were replaced with fresh medium (Dulbeco Modified Eargle's Medium, DMEM) without serum for 24, 48 and 72 h. Then, the conditioned medium (CM) was collected. CM (24, 48 and 72 h) from HuCCA failed to induce platelet aggregation, whereas, HuCCA pellets induced platelet aggregation and potentiated platelet aggregation induced by submaximal concentration of thrombin. Interestingly, platelet aggregation induced by HuCCA was inhibited by hirudin (thrombin receptor antagonist; 10, 20 and 40 U) in a dose dependent manner. Thus, Cholangiocarcinoma cells can induce platelet aggregation in a direct tumor cell-platelet contact via thrombin receptor. Therefore, the use of antiplatelet agents especially via thrombin receptors may help to prevent TCIPA or metastasis by CCA.Publication Metadata only Efficacy and safety of Menatetrenone-4 postmenopausal Thai women(2001-12-01) Narong Bunyaratavej; Nipat Kittimanon; Aviga Bonjongsat; Pornthip Penkitti; Peerapong Boonsangsom; Somporn Yunoi; Mahidol UniversityClinical and comparative study of the efficacy and adverse events of Menatetrenone-4. The control group (n=40) received elemental calcium carbonate 800 mg/day and the Menatetrenone-4 treated group received elemental calcium carbonate 800 mg/day plus vitamin K2 45 mg/day (n=43). The vitamin K2 treated group showed a marked decrease of undercarboxylated osteocalcin at 2 weeks, six months (51.52% p=0.0001) and twelve months (87.26% p=0.0001) compared to the calcium treated group. At the end of the sixth and twelve months both groups did not increase bone mass of the hip but the vitamin K2 treated group increased 0.6 percent of bone mass of the lumbar spine and decreased bone resorption 65.42 percent (p=0.0001) compared to the calcium treated group. The calcium treated group was switched to the vitamin K2 treated group at the end of six months and showed a decrease of the level of undercarboxylated osteocalcin the same as the former vitamin K2 treated group. The adverse events were 2 cases of mild skin rash which subsided after cessation of medication.Publication Metadata only Low genetic diversity in Japanese populations of the Eurasian badger Meles meles (Mustelidae, Carnivora) revealed by mitochondrial cytochrome b gene sequences(2001-11-01) Naoko Kurose; Yayoi Kaneko; Alexei V. Abramov; Boripat Siriaroonrat; Ryuichi Masuda; Graduate School of Science; Japan National Institute for Land and Infrastructure Management; Zoological Institute, Russian Academy of Sciences; Mahidol University; Hokkaido UniversityTo assess the level of genetic variations of the Eurasian badger Meles meles in Japan, the entire sequences (1,140 base pairs) of the mitochondrial cytochrome b gene were phylogenetically examined. Most of substitutions between haplotypes were transitions resulting in synonymous mutations. A phylogenetic tree reconstructed by sequence differences clearly showed that Japanese populations of Meles meles were differentiated from continental populations (from the Baikal area and eastern Europe) of M. meles. By contrast, genetic distances among Japanese populations were much smaller, and their geographic structures did not reflect geographic distances between sampling localities. The results indicate that polymorphisms of the ancestral populations still remain via loss of haplotypes by population size changes. In addition, M. meles could have occupied the present habitats in Japanese main islands (Honshu, Shikoku, and Kyushu) in a short period, possibly after the last glacial age.Publication Metadata only Study of the level of biochemical bone markers: NMID osteocalcin and bone resorptive marker (beta CTx) in Thai women(2001-10-01) Narong Bunyaratavej; Nipat Kitimanon; Siriwan Boonthitikul; Mahidol University; Praputhjinaraj HospitalStudy of the level of NMID osteocalcin and Beta CTx in 700 Thai women. The mean of NMID osteocalcin = 21.45 SD = 11.18 95% CI = 20.12 to 22.79 ng/ml and beta crosslap = 0.445 ng/ml SD = 0.25 with 95% CI = 0.414 to 0.478 ng/ml in women who menopaused less than 10 years ago (n=237), these values were higher than in young adult females (n=63) and menstruating women (n=123) which was statistically signigficant (p=0.0001). The value of both bone markers in elderly women who had menopaused more than 10 years ago and were aged more than 60 years (n=94) showed a marked increase of NMID osteocalcin, 25.63 ng/ml SD = 14.22 ng/ml but the value of betacrosslap was below the young- menopausal women, 0.394 ng/ml SD = 0.241 ng/ml 95% CI = 0.344 to 0.444 ng/ml. Menopausal women are at a high risk of osteoporosis due to high bone turnover. In our study, the NMID osteocalcin had a high correlation with betacrosslap (r=0.789 p=0.0001) while both bone markers had a weak correlation with bone mass density of radius, lumbar spine and hip by DXA. (r=0.29 p=0.0001).Publication Metadata only Clinical trial of halofantrine with modified doses for treatment of malaria in the hospital for tropical diseases(2001-06-01) Srivicha Krudsood; Pratap Singhasivanon; Udomsak Silachamroon; Sombat Treeprasertsuk; Wongphan Kaivipakbanyai; Kobsiri Chalermrut; Nuntaporn Phophak; John Horton; Dennis Kyle; Sornchai Looareesuwan; Mahidol University; GlaxoSmithKline plc.; Armed Forces Research Institute of Medical Sciences, ThailandThe spread of falciparum malaria resistant to chloroquine all over Southeast Asian continent has led to increasing use of alternative antimalarial drugs. Halofantrine has been shown to be effective against multidrug resistant Plasmodium falciparum. One hundred and twenty falciparum malaria cases were randomly assigned to one of three different halofantrine regimes. Group I (HA1) received 500 mg three times daily for 3 days (total dose: 4,500 mg), group II (HA2) received 500 mg three times daily for the first and the third day (total dose: 3,000 mg) and group III (HA3) received 500 mg three times for one day followed by 500 mg once daily for 7 days (total dose: 4,500 mg). No significant difference in the cure rate was observed among the three regimes (cure rate: 89%, 73%, 97% respectively). However, the cure rate was significantly higher in the HA3 group when compared to the HA2 group. There were no overt cardiac problems seen in this study. Thus, halofantrine has high efficacy in the recommended treatment dose of 500 mg three times after meals on the first day followed by 500 mg once a day after a meal for 7 days (total dose: 4,500 mg).Publication Metadata only Fake artesunate in southeast Asia(2001-06-16) Paul Newton; Stephane Proux; Michael Green; Frank Smithuis; Jan Rozendaal; Sompol Prakongpan; Kesinee Chotivanich; Mayfong Mayxay; Sornchai Looareesuwan; Jeremy Farrar; Francois Nosten; Nicholas J. White; Mahidol University; John Radcliffe Hospital; Shoklo Malaria Research Unit; Centers for Disease Control and Prevention; Médecins Sans Frontieres (Netherlands); Centre for Tropical Diseases Vietnam; European Commission/Cambodia Malaria Control ProjectArtesunate is a key antimalarial drug in the treatment of multidrug-resistant Plasmodium falciparum malaria in southeast Asia. We investigated the distribution of counterfeit artesunate tablets by use of the validated, simple, and inexpensive Fast Red TR dye technique. We also aimed to identify distinguishing characteristics of the fake drugs. Of 104 shop-bought "artesunate" samples from Cambodia, Laos, Myanmar (Burma), Thailand, and Vietnam, 38% did not contain artesunate. Characteristics such as cost and physical appearance of the tablets and packaging reliably predicted authenticity. The illicit trade in counterfeit antimalarials is a great threat to the lives of patients with malaria. The dye test will assist national malaria control authorities in urgently needed campaigns to stop this murderous trade.Publication Metadata only Can serial qualitative polymerase chain reaction monitoring predict outcome of pulmonary tuberculosis treatment?(2001-12-01) Nitipatana Chierakul; Angkana Chaiprasert; Nipa Tingtoy; Wiyada Arjratanakul; Sa Nga Pattanakitsakul; Mahidol UniversityBackground: The aim of this study was to assess the use of qualitative one-tube nested polymerase chain reaction (PCR) for monitoring the treatment response in smear-positive pulmonary tuberculosis, and the factors determining the negative conversion of sputum smear, culture, and PCR during treatment. Methodology: A total of 53 patients receiving a standard short course of chemotherapy with 24 months follow-up period after treatment cessation were included in the study. Sputum specimens were collected serially for smear, culture, and PCR until the treatment was complete. Results: The conversion rate for sputum culture, smear, and PCR at 8 weeks after treatment were 84.9, 58.5, and 47.1%, and at 16 weeks of treatment were 100, 88.7, and 79.2%, respectively. At the end of the treatment period, there were four PCR persisters, one of whom had disease relapse. Only cavitary disease had an influence over the negative conversion of the smear and PCR at 8 weeks (RR 3.5, 95% CI 1.04-11.95, P = 0.04 for smear; RR 5.06, 95% CI 1.196-21.42, P = 0.03 for PCR). Conclusion: Qualitative PCR was not useful for monitoring therapy in smear-positive pulmonary tuberculosis. Mycobacterium DNA was cleared slowly in cavitary disease. The PCR may be performed at the time of treatment cessation to identify those with potential for disease relapse.Publication Metadata only Diagnosis of intestinal amebiasis using salivary IgA antibody detection(2001-12-01) Paibul Punthuprapasa; Nitaya Thammapalerd; Udomporn Chularerk; Kravee Charoenlarp; Manoon Bhaibulaya; Faculty of Medicine, Siriraj Hospital, Mahidol University; Mahidol UniversityAttempts were made to use soluble antigen extract of strain HK-9 of Entamoeba histolytica to detect salivary IgA antibodies in intestinal amebiasis patients by using ELISA. Total salivary samples of 109 individuals were divided into four groups. Group I comprised 32 patients whose stools were positive only for E. histolytica cysts and/or trophozoites. Group II comprised 12 individuals whose stools were positive for E. histolytica and other intestinal parasites. Group III comprised 36 individuals whose stools were negative for E. histolytica but contained other intestinal parasites such as E. coli, E. nana, Blastocystis hominis, Trichomonas hominis. Giardia lamblia. Opisthorchis viverrini, and hookworm. Group IV comprised 29 healthy individuals whose stools were free from any intestinal parasitic infections. Based on the mean optical density, OD + 2SD of the results from 29 parasitologically negative healthy individuals, the cut-off OD value for salivary IgA antibodies was 1.265. Therefore, the assays were positive in 14 out of 32 (43.75%) of group 1 and 2 out of 12 (16.6%) of group II. The assays were positive in 16 out of 36 (44.44%) for group III whereas 2 out of 29 (6.90%) for group IV were positive. The overall sensitivity and specificity of the assays were 36% and 72%, respectively. The false positive rate was 28% and the false negative rate was 64%. The predictive values of positive and negative results were 47% and 63%, respectively. The diagnostic accuracy of ELISA for the presence of salivary IgA antibodies was 58%.Publication Metadata only Burkholderia pseudomallei-specific recombinant protein and its potential in the diagnosis of melioidosis(2001-08-14) P. Wongprompitak; C. Thepthai; S. Songsivilai; T. Dharakul; Mahidol UniversityMelioidosis is an important public health problem in Southwest Asia and Northern Australia. This disease is caused by the gram-negative bacilli, Burkholderia pseudomallei. Wide spectra of clinical manifestations are observed in melioidosis ranging from asymptomatic to septicemic infection. Although serodiagnostic methods of melioidosis have been improved significantly in recent years, a highly specific diagnostic test that can differentiate asymptomatic seropositive individuals and melioidosis patients remains to be the subject of current investigations. In this study, a B. pseudomallei-specific gene, pBps-1, expressing a novel 18.7 kDa recombinant protein was selected from genomic libraries of two B. pseudomallei virulent isolates by using pooled sera from septicemic melioidosis patients. Nucleotide sequence analysis demonstrated that this gene is unique and does not show substantial similarity with any known genes in the Genbank database. The Bps-1 recombinant protein was evaluated for its potential in serodiagnosis of melioidosis by Western blot analysis. A high degree of specificity was demonstrated using sera from healthy individuals in the endemic (98.5%) and non-endemic areas (100%), with moderate sensitivity (69.7%) in melioidosis patients. The study demonstrated that this approach can be used to obtain highly specific recombinant antigens such as that described in the present report. A combination of such antigens should provide materials for successful serodiagnosis of melioidosis in the endemic areas.Publication Metadata only Combined fresh frozen plasma with recombinant factor VIIa in restoring hemostasis for invasive procedures in children with liver diseases(2001-04-24) A. Chuansumrit; S. Treepongkaruna; P. Phuapradit; Mahidol UniversityPublication Metadata only Erratum: A double-blind, adjuvant-controlled trial of human immunodeficiency virus type 1 (HIV-1) immunogen (remune) monotherapy in asymptomatic, HIV-1-infected thai subjects with CD4-cell counts of >300 (Clinical and Diagnostic Laboratory Immunology (2000) 7:5 (728-733))(2001-01-01) V. Churdboonchart; C. Sakondhavat; S. Kulpradist; B. Isarangkura Na Ayudthya; V. Chandeying; S. Rugpao; C. Boonshuyar; W. Sukeepaisarncharoen; W. Sirawaraporn; D. J. Carlo; R. Moss; Mahidol UniversityPublication Metadata only Mitrofanoff procedure incombination with enterocystoplasty for detrusor hyperreflexia with external sphincter dyssynergia: One-year experience of 12 cases(2001-07-01) Wachira Kochakarn; Verasing Muangman; Mahidol UniversityTwelve patients with the mean age of 35 years who had undergone Mitrofanoff procedure incombination with enterocystoplasty between 1998-1999 were interviewed. All of the patients had suprasacral spinal cord injuries for the mean of 3.5 years from the accident to the operation and failure of medical treatment to suppress hyperreflexic bladder. The vermiform appendix was used to implant as continent stoma in 10 cases and ileal segment was used in 2 cases due to prior appendectomy. The bladder capacity was increased from the mean of 180 ml before the operation to 300 ml intraoperation and 800 ml at 1 year post-operation. Up to 1 year, no immediate and late complication was detected except one case who had orchitis at eleven months post-operation. All of them still have continence and self-intermittent catheterization can easily be performed via con-tinent stoma at the abdominal wall.Publication Metadata only Biochemical markers of bone turnover and response of bone mineral density to intervention in early postmenopausal women: An experience in a clinical laboratory(2001-06-11) L. O. Chailurkit; B. Ongphiphadhanakul; N. Piaseu; S. Saetung; R. Rajatanavin; Mahidol UniversityBackground: Markers of bone formation and resorption may be useful as early indicators of response to therapy. Our aim in this study was to investigate the use of bone markers for monitoring of intervention for bone loss in early postmenopausal women and to assess the relationships between these markers and changes in bone mineral density (BMD). Methods: Subjects were randomly assigned to the following groups: a control group; a group receiving calcium alone; groups receiving calcium plus low or conventional doses of conjugated equine estrogen; and groups receiving calcium plus low or conventional doses of calcitriol. At baseline and at 1 and 3 months after intervention, we measured serum intact osteocalcin, serum N-terminal midfragment osteocalcin, serum C-terminal telopeptide of type I collagen (CTx), urinary deoxypyridinoline cross-links, and urinary CTx. The BMD of the lumbar spine and the femoral neck was measured at baseline and after 1 and 2 years of intervention. Results: No marker changed significantly in the control group except urinary CTx, which increased at 3 months. Serum CTx decreased in all regimens at 1 or 3 months of intervention. In addition, the changes of all markers at 3 months were inversely associated with the change in the BMD of the lumbar spine at 1 or 2 years (r = -0.144 to -0.314), whereas only the changes of bone resorption markers at 3 months were inversely correlated with the changes in femoral BMD at 1 or 2 years (r = -0.143 to -0.366). Conclusions: Biochemical markers of bone turnover appear to be of use in assessing early response to therapy. Bone resorption markers, especially serum CTx, are better indicators than bone formation markers for estimating the response to intervention in early postmenopausal women. However, the early changes in bone markers were weakly related to the later changes in BMD. © 2001 American Association for Clinical Chemistry.Publication Metadata only Viral load differences in early infection with two HIV-1 subtypes(2001-04-13) Dale J. Hu; Suphak Vanichseni; Timothy D. Mastro; Suwanee Raktham; Nancy L. Young; Philip A. Mock; Shambavi Subbarao; Bharat S. Parekh; La Ong Srisuwanvilai; Ruengpung Sutthent; Chantapong Wasi; Walid Heneine; Kachit Choopanya; National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention; Bangkok Metropolitan Administration; HIV/AIDS Collaboration; National Center for Infectious Diseases; Mahidol UniversityObjectives: Information on early HIV-1 infection has come primarily from studies of persons infected with subtype B in North America and Europe; much less is known about other subtypes. The purpose of the present study was to compare the virologic and immunologic parameters following seroconversion among recently-infected persons infected with either of two different HIV-1 subtypes. Method: A prospective cohort study was carried out at methadone treatment clinics administered by the Bangkok Metropolitan Administration, Thailand. A total of 130 HIV-1-infected seroconverters (103 with HIV-1 subtype E and 27 with subtype B) were included in the study. The main outcome measures were serial HIV-1 RNA viral load, natural killer cell percentage, CD4 and CD8 lymphocyte counts since seroconversion. Results: The demographic and behavioral characteristics of persons with either subtype were similar. Median RNA viral levels at the earliest time within 3 months of seroconversion were more than three times higher for persons infected with subtype E than subtype B (63 100 versus 18 050 copies/ml, P = 0.001). However, this difference decreased over time such that viral loads were similar at 12, 18, and 24 months following seroconversion. The CD4 and CD8 lymphocyte counts were similar in infections with either subtype during the entire period up to 24 months post-seroconversion. Conclusions: Higher viral loads associated with subtype E may result from inter-subtype biological differences; however, the epidemiological dynamics of transmission in Bangkok may have also contributed to this phenomenon. © 2001 Lippincott Williams & Wilkins.