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Biomedical subjects

S Isomura

Publications and source records attributed to S Isomura.

At least 19 recordsLinked to original sources
PubMed2001

An immunotherapeutic program for the treatment of nicotine addiction: hapten design and synthesis.

People continue to smoke and use tobacco products despite well-established hazardous consequences. The most contributing factor is the addictive nature of nicotine. There is no highly effective treatment for the problem of nicotine dependence. Immunotherapy offers an alternative to conventional approaches. The chemistry necessary for a comprehensive immunopharmacological program is presented. Haptens for the generation of antibodies specific for naturally occurring (S)-nicotine, (S)- and (R)-nornicotine, and the metabolite (S)-cotinine were prepared with high optical purity. Preliminary data for antinicotine antibodies are reported.

Haptens↗
PubMed2000

Rotavirus infection among infants with diarrhea in Vietnam.

Rotavirus was examined from diarrheal stool samples of 158 infants in rural area near Ho Chi Minh City, Vietnam, from 1994 to 1996. Group A rotavirus was detected in 50%. G1 and G4 were the predominant serotypes. G3 was not detected. The most predominant type changed from year to year. Rotavirus was found in all seasons, especially in winter and autumn. Infants younger than 2 years of age were those mostly infected and the virus was suspected to invade high concentration in this area.

Diarrhea↗
PubMed2000

Rotavirus infection among infants with diarrhea in Pakistan.

Rotavirus was examined in 818 diarrheal stool samples collected in Karachi, Pakistan, from 1990 to 1997. Rotavirus was detected in 112 samples (13.7%). The predominant serotypes were G1 and G4 and G3 was not detected. The predominant type changed between years. Rotavirus was found in all seasons and most infections were found in children aged less than 2 years.

Diarrhea↗
PubMed2000

Properties of hepatitis B virus genome recovered from Vietnamese patients with fulminant hepatitis in comparison with those of acute hepatitis.

Among the many mutations found in the hepatitis B virus (HBV) genome, some have been associated with fulminant hepatitis, as exemplified by precore-defective mutations. The aim of this study was to determine whether such mutations also are found in Vietnamese cases of fulminant hepatitis B. The full-genome nucleotide sequence of HBV in three patients with fulminant hepatitis (F-2, F-3, and F-6) and one with acute hepatitis (A-3), who were admitted to Cho Ray Hospital, Ho Chi Minh City, Vietnam was ascertained. Additionally, two patients with fulminant hepatitis (F-1 and F-7) and three with acute hepatitis (A-1, A-2, and A-5) were examined only for the precore/core region of HBV. Remarkably, the nonsense mutation at precore codon 28 (Trp82Stop) was found in four of the five patients with fulminant hepatitis, while all the acute hepatitis patients harbored wild type (one had a mixture of wild and mutant types). The missense mutations within the core region, Ile97Leu and Pro130Ile/Thr/Ser, were also remarkable in fulminant hepatitis. Only F-2 was free from these precore/core mutations, but F-2 was unique in that it possessed a chimeric genotype: it could be classified into genotype C as a whole, but its X region was of genotype B, like the other four fulminant hepatitis isolates (F-1, F-3, F-6, and F-7). The codon 41 of the X protein was Pro in all three fulminant hepatitis cases examined for this region, while it was Ser in the wild-type isolates of genotype B. Of note as negative data, the mutations C1653T and T1753M of the enhancer II (Enh II) and A1762T and G1764A of the precore/core promoter regions, once reported to be relevant to severe or fulminant hepatitis, were not found in the present cases. The results with the Vietnamese cases of fulminant hepatitis corroborated results of previous studies with respect to the mutations Trp28Stop of precore and Ile97Leu and Pro130Ile/Thr/Ser of core, but not for the mutations within Enh II and precore/core promoter region. Whether the Ser41Pro mutation in the X region of genotype B HBV is Vietnam-specific or disease-specific deserves further investigation.

Adult↗
PubMed2000

Intratypic differentiation & partial nucleotide sequencing of poliovirus isolates of northern India.

The potential resolving power of molecular epidemiological studies has enhanced the precision and reliability of poliovirus (PV) surveillance. PV has an error prone RNA polymerase responsible for rapid evolution of genome (approximately 10(-2) nt substitution/site/year), during inter and intra-human passages. The present study included a serotyped panel of 60 PV (42 PV type-1, 13 PV type-2 and 5 PV type-3) isolated during 1997. They were differentiated into vaccine (Sabin) and wild strains by two methods viz., genotype specific RNA probe hybridization (Rpro-Hy) based on genotypic variability; and ELISA that uses cross-absorbed antiserum (Pab-E) based on phenotypic variability. For obtaining information on molecular epidemiology, partial nucleotide sequencing (VP1/2A region) of five clinical PV isolates was also done. Three of the 60 isolates (two PV type-1 and one PV type-3) intratyped, could not be differentiated correctly by either method. Genotypic characterization of PV isolates was done for confirmation of intratyping results. All five wild PV1 sequenced belonged to the same genotype (> 85% homology) and sequence divergence among the strains was < or = 4.5 per cent. This indicated circulation of a single genetic lineage in the area.

Base Sequence↗
PubMed2000

Sequence diversity of serine repeat antigen gene exon II of Plasmodium falciparum in worldwide collected wild isolates.

Field isolates of Plasmodium falciparum collected from endemic areas of Southeast Asia, Solomon Islands, tropical African countries and Brazil were analyzed for the genetic diversity of the exon II of serine repeat antigen gene (SERA) by sequencing of genomic DNA. Of sixty-nine isolates, as compared to the reported FCR3, K1 and Honduras-1 types of exon II sequences, 5, 9 and 20 new allelic forms were found in 23 isolates of the FCR3 type, 36 of the K1 type and 10 of the Honduras-1 type. A group of novel non-synonymous substitutions, 4 new insertions and 3 new deletions of octamer units were found in the octamer repeat region (OR) of the exon II, and most of them clustered within a 40-residues domain. An octamer "SNPVSSEP" revealed in the OR was confirmed as a new repeat unit. Based on the sequences of the serine repeat region (SR) of the exon II, the allelic forms of the Honduras-1 type were conjectured to be the recombinant forms between the K1 type and FCR3 type. The allelic forms of K1 type with less or more repeat serine residues in the serine stretch of the SR than the reported 21 serine residues had most of the variations in the OR. Moreover, a biased geographical distribution of allelic forms was observed. Isolates from African and Southeast Asian countries accounted for most of the new allelic forms (29/33). All of the three types were detected in Southeast Asia but none of the FCR3 type in Africa. One of two groups of FCR3 new allelic forms was found solely in Brazil while another was mainly in Solomon Islands.

Alleles↗
PubMed1999

An infectious DNA clone of HIV type 1 subtype C.

Among the 10 subtypes of the M group of human immunodeficiency virus type 1, subtype C is the most prevalent in India and may dominate worldwide in the near future; however, there has been no report on the infectious DNA clone of this subtype. We have isolated an infectious DNA clone of the 93IN101 strain of HIV-1 subtype C, which was isolated in India in 1993. MAGIC5 cells, which are derived from HeLa-CD4-LTR-beta-gal (MAGI) cells and express CCR5, were inoculated with the 93IN101 strain of HIV-1 subtype C. The genomic DNA of the infected cells was used as a template for amplification of the HIV-1 genome. The genome DNA obtained was subcloned into pBR322, and the resulting plasmid was designated as pIndie-C1. The insert of pIndie-C1 was 9680 bp in length and had an intact genomic organization with open reading frames of all structural, regulatory, and accessory proteins. Phylogenetic analysis confirmed that the nucleotide sequence of pIndie-C1 is closely related to those of HIV-1 subtype C isolated in India. Transfection of pIndie-C1 into 293T cells yielded as much virus as did pNL432, one of the most widely used HIV DNA clones. The recovered Indie-C1 virus infected MAGIC5 but not the parent MAGI cells, indicating that Indie-C1 is CCR5 tropic. Expressed Env protein was reacted efficiently with the sera of HIV-1-infected patients of India, but not of Japan. Expression of Nef and Vpr was also confirmed by immunoblotting.

Gene Products, env↗
PubMed1999

Phospholipase A2-like catalytic antibody.

The phospholipase A2-like catalytic antibody 13C2-1F6 was elicited against the hapten 1 as the transition state analog for the hydrolysis of the C2 ester in the phospholipid. The Michaelis-Menten kinetics for the hydrolysis of the phospholipid 2 by 13C2-1F6 afforded a kcat of 1.0 x 10(-2) min(-1) and aKm of 71 microM. This antibody hydrolyzes the C2 ester in (R)-2, regio- and enantioselectively.

Antibodies, Catalytic↗
PubMed1999

Evaluation of an enzyme-linked immunosorbent assay based on binding inhibition for type-specific quantification of poliovirus neutralization-relevant antibodies.

To detect neutralization-relevant antibodies against 3 types of poliovirus (PV) without using tissue cultures and live viruses, an enzyme-linked immunosorbent assay (ELISA) based on monoclonal antibody-binding inhibition was evaluated using sera from 80 vaccinated Japanese children and 60 Pakistani poliomyelitis patients. Compared with the neutralization test, the sensitivity of the inhibition ELISA was 100% (111/111) for detection of anti-PV1 antibody, 98.3% (118/120) for anti-PV2, and 96.5% (82/85) for anti-PV3, and the specificity was 93.1% (27/29), 100% (20/20), and 92.7% (51/55), respectively. Thus, the inhibition ELISA showed excellent potential as a seroepidemiologic tool in both vaccinated and naturally-infected populations.

Animals↗
PubMed1998

Correlation analysis between fatty acid compositions of zooplankter individuals, fed on different phytoplankton species by means of pyrolysis-gas chromatography combined with on-line methylation.

Pyrolysis-gas chromatography (Py-GC) combined with on-line methylation was applied to a correlation analysis between the distributions of fatty acid components in the lipids of zooplankter individuals and those of ingested algae using principal component analysis (PCA). Py-GC in the presence of organic alkali, tetramethylammonium hydroxide (TMAH), was used to estimate the apparent distributions of fatty acid components contained in a single individual zooplankter weighing several tens of micrograms and a small sample size of ingested algae samples in the order of 10 microg. The observed fatty acid compositions were used as a database for the PCA in order to discriminate the zooplankton and ingested algae samples. The result obtained indicated that the fatty acid compositions of zooplankton individuals used in this work were significantly reflected in those of their ingested food in spite of some contribution from isomerization and/or elongation of fatty acid components during digestion of the ingested algae phytoplankton in living zooplankters.

Animals↗
PubMed1998

An epidemiologic study of herpes simplex virus type 1 and 2 infection in Japan based on type-specific serological assays.

A seroepidemiologic study of herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) was performed on Japanese adults. Serum samples collected between 1985-9 from a total of 536 healthy adults, female prostitutes, males with sexually transmitted diseases (STD), homosexual men, and pregnant women were studied by immunodot assays using HSV type-specific antigens, glycoproteins G (gG1 and gG2). HSV-1 infections correlated mostly with age and was widely prevalent among subjects < 40 years. HSV-2 prevalence varied greatly among subgroups defined by sexual activity and was associated with risk behaviours for prostitution, infection with STD, and homosexual activity. HSV-2 seroprevalence was highest among prostitutes (80%), lowest among pregnant women (7%), and intermediate in STD patients (23%) and homosexuals (24%). Because HSV-1 infection during childhood has been decreasing, primary genital HSV-2 infection, with its higher frequency of clinical manifestations, will become a greater burden to the public health in Japan.

Adult↗
PubMed1998

High prevalence of Plasmodium malariae and Plasmodium ovale in malaria patients along the Thai-Myanmar border, as revealed by acridine orange staining and PCR-based diagnoses.

The prevalence of the four human malaria parasites was investigated among malaria patients at northern, central and southern towns in Thailand along the border with Myanmar between September 1995 and May 1996. Thin smears obtained from 548 Thai and Burmese patients were reviewed by an acridine orange staining method, and many mixed infections with two to four species, including P. malariae and P. ovale, were detected. These diagnostic results were compared with those by two PCR-based diagnoses, microtitre plate hybridization (MPH) and a nested PCR method, both of which targets the same, species-specific regions in the 18S rRNA genes. In both PCR diagnoses, many P. malariae and P. ovale infections were also detected. Detection sensitivity of P. malariae infection was higher in nested PCR than MPH, and a total prevalence of P. malariae infection estimated by nested PCR reached 24.3% (133/548). In 16 of them, the size of PCR products amplified by the P. malariae-specific primer was about 20-bp shorter than the expected size of 115-bp. Four of 16 possessed two different bands with normal and shorter sizes, suggesting that P. malariae isolates may be separated into two types, and that those with shorter products may be new variant form (s) with a nucleotide deletion in the target region. On the other hand, 21 P. ovale infections (3.8%) were detected by nested PCR, but four of them were MPH-negative because of the sequence variation at the probe region. These results indicated that the prevalence of P. malariae and P. ovale along the Thai-Myanmar border may be substantially higher than previously reported.

Acridine Orange↗
PubMed1998

Sequence variation in the small-subunit rRNA gene of Plasmodium malariae and prevalence of isolates with the variant sequence in Sichuan, China.

By two PCR-based diagnostic methods, Plasmodium malariae infections have been rediscovered at two foci in the Sichuan province of China, a region where no cases of P. malariae have been officially reported for the last 2 decades. In addition, a variant form of P. malariae which has a deletion of 19 bp and seven substitutions of base pairs in the target sequence of the small-subunit (SSU) rRNA gene was detected with high frequency. Alignment analysis of Plasmodium sp. SSU rRNA gene sequences revealed that the 5' region of the variant sequence is identical to that of P. vivax or P. knowlesi and its 3' region is identical to that of P. malariae. The same sequence variations were also found in P. malariae isolates collected along the Thai-Myanmar border, suggesting a wide distribution of this variant form from southern China to Southeast Asia.

Animals↗
PubMed1998

Allelic diversity at the merozoite surface protein-1 locus of Plasmodium falciparum in clinical isolates from the southwestern Brazilian Amazon.

Nucleotide sequences of each variable block in the Plasmodium falciparum merozoite surface protein-1 gene (PfMSP-1) may be grouped into one of two or three possible allelic types, named after the reference isolates MAD20, K1, and RO33. Allelic diversity at this locus basically results from different combinations of allelic types in variable blocks. We used a polymerase chain reaction (PCR)-based strategy to type the variable blocks 2, 4a, 4b, and 10 of the PfMSP-1 gene of P. falciparum isolates from 54 symptomatic malaria patients living in Rondonia, a hypoendemic area in the southwestern Brazilian Amazon. Ten different PfMSP-1 gene types, defined as unique combinations of allelic types in variable blocks, were identified among the 54 isolates. Twenty-one isolates (39%) harbored more than one gene type and two had at least three genetically distinct clones. Hybrid sequences, with a MAD20-type sequence in the 5' segment (4a) and a K1-type sequence in the 3' segment (4b), were quite common in block 4. Direct sequencing of block 4 PCR products revealed a new putative recombination site in four isolates. In contrast with previous studies, the observed distribution of gene types does not deviate significantly from that expected under the null hypothesis of random association between allelic types detected in each variable block. These contradictory data are discussed with reference to the immunoepidemiologic features prevailing in distinct malaria-endemic areas.

Adolescent↗
PubMed1998

Prevalence of hepatitis B, hepatitis C, and GB virus C/hepatitis G virus infections in liver disease patients and inhabitants in Ho Chi Minh, Vietnam.

The prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), and GB virus C or hepatitis G virus (GBV-C/HGV) infections was determined in 289 patients with liver disease in Ho Chi Minh City and 890 healthy inhabitants of its rural area, Dalat City, Vietnam, respectively. Serum HCV RNA and GBV-C/HGV RNA were detected by reverse transcription-polymerase chain reaction (RT-PCR). HBsAg, HCV antibodies, and GBV-C/HGV RNA were detected in 139 (47%), 69 (23%), and ten (3%) subjects, respectively, often accompanied by elevated serum levels of alanine aminotransferase. HBsAg and HCV antibodies or HCV antibodies and GBV-C/HGV RNA were detectable simultaneously in 8% and 2% of the patients, respectively. In the inhabitants, HBsAg, HCV antibodies, and GBV-C/HGV RNA were found in 51 (5.7%), nine (1.0%), and 11 (1.2%) subjects, respectively. Thus, the prevalence of HBsAg, HCV antibodies, and GBV-C/HGV RNA was significantly higher in liver disease patients than those in the general population. In the samples from 69 patients and nine inhabitants who were seropositive for HCV antibodies, HCV RNA was detectable in 42 (61%) and 4 (44%), respectively. In patients with liver disease, ten belonged to HCV genotype 1a, ten to HCV 1b, three to HCV 2a, four to HCV 2b, and two to HCV 3a by PCR with genotype-specific primers. Nine patients had mixed genotypes, and the remaining four were not classified. Of the GBV-C/HGV RNA-positive individuals, two patients and two inhabitants were positive for HBsAg, while none of the residents had HCV antibodies, although six HCV antibodies (60%) and four HCV RNA (40%) were found in patients. When a phylogenetic tree of GBV-C/HGV was constructed based on the nucleotide sequences, the 21 isolates were classified into at least two genotypes; four isolates belonged to G2, and 17 to G3. The results indicate that in Ho Chi Minh HCV infection prevails with broad distribution of genotypes together with HBV infection among patients with liver disease. This study suggests that GBV-C/HGV infection occurs independently in the two different districts in association with HCV infection.

Adolescent↗
PubMed1996

Epidemiology of poliomyelitis in Karachi, Pakistan: prospective studies during 1990-93.

Between October 1989 and September 1993, 245 cases of poliomyelitis visited the Department of Pediatrics, Civil Hospital Karachi, Pakistan. The majority of them were between 6 months and 2 years of age and the epidemic occurred during the hot season. The dominant serotype was polio type 1. All of the polioviruses isolated from the patients were wild type. Virological studies also disclosed that enteroviruses other than polioviruses were prevalent among healthy children as well as diarrheal and polio patients. Serodiagnosis by poliovirus-specific immunoglobulin M antibody tests using the capture enzyme-linked immunosorbent assay method were in good agreement with the results of virus isolation. The present study demonstrated that Pakistan is a region endemic for wild poliovirus and more aggressive preventive measures are needed to eradicate poliomyelitis from the region.

Child, Preschool↗