Biomedical subjects

Minoru Nakao

Publications and source records attributed to Minoru Nakao.

35 records · Page 2Linked to original sources

PubMed2004

DNA differential diagnosis of taeniasis and cysticercosis by multiplex PCR.

Multiplex PCR was established for differential diagnosis of taeniasis and cysticercosis, including their causative agents. For identification of the parasites, multiplex PCR with cytochrome c oxidase subunit 1 gene yielded evident differential products unique for Taenia saginata and Taenia asiatica and for American/African and Asian genotypes of Taenia solium with molecular sizes of 827, 269, 720, and 984 bp, respectively. In the PCR-based detection of tapeworm carriers using fecal samples, the diagnostic markers were detected from 7 of 14 and 4 of 9 T. solium carriers from Guatemala and Indonesia, respectively. Test sensitivity may have been reduced by the length of time (up to 12 years) that samples were stored and/or small sample volumes (ca. 30 to 50 mg). However, the diagnostic markers were detected by nested PCR in five worm carriers from Guatemalan cases that were found to be negative by multiplex PCR. It was noteworthy that a 720 bp-diagnostic marker was detected from a T. solium carrier who was egg-free, implying that it is possible to detect worm carriers and treat before mature gravid proglottids are discharged. In contrast to T. solium carriers, 827-bp markers were detected by multiplex PCR in all T. saginata carriers. The application of the multiplex PCR would be useful not only for surveillance of taeniasis and cysticercosis control but also for the molecular epidemiological survey of these cestode infections.

Animals↗

PubMed2004

Molecular cloning, expression, and serological evaluation of an 8-kilodalton subunit of antigen B from Echinococcus multilocularis.

Full-length cDNA and genomic DNA encoding an 8-kDa subunit of antigen B from Echinococcus multilocularis (designated EmAgB8/1) were isolated from an E. multilocularis metacestode cDNA library and a protoscolex genomic DNA library, respectively. The open reading frame of the cDNA clone encodes a polypeptide comprising 85 amino acids with a 20-amino-acid NH(2)-terminal signal sequence, which was confirmed following N-terminal sequencing of the native antigen. Reverse transcription-PCR analysis revealed that the clone encoding EmAgB8/1 is predominantly transcribed in larval E. multilocularis. The gene consists of two exons (encoding the signal sequence and mature protein) separated by a 91-bp intron. The mature form was expressed in Escherichia coli, and its antigenic reactivity was compared with that of a counterpart, an 8-kDa subunit of antigen B from Echinococcus granulosus (EgAgB8/1) by Western blotting and enzyme-linked immunosorbent assay (ELISA) with serum samples from patients confirmed to have cystic echinococcosis (CE) and alveolar echinococcosis (AE). Recombinant EmAgB8/1 showed positive reactions in Western blots with 81.3% (65 of 80) of serum samples from CE patients and 40.6% (26 of 64) of serum samples from AE patients, while recombinant EgAgB8/1 showed positive reactions with 86% (43 of 50) and 42% (19 of 45) of the serum samples from these CE and AE patients, respectively. By the ELISA, both EmAgB8/1 and EgAgB8/1 exhibited similar positive reactions with 88% (44 of 50) of serum samples from CE patients and 37.8% (17 of 45) serum samples from AE patients. Statistical analysis revealed that the sensitivity of EmAgB8/1 was comparable to that of EgAgB8/1 for the serodiagnosis of echinococcal diseases. There was no cross-reaction with sera from patients with cysticercosis, which often cross-react when native antigens are used for serodiagnosis.

Amino Acid Sequence↗

PubMed2004

Solitary neurocysticercosis case caused by Asian genotype of Taenia solium confirmed by mitochondrial DNA analysis.

A Japanese woman presenting with neurologic symptoms was presumptively diagnosed with neurocysticercosis based on imaging findings. Hooklets in the scolex of the resected lesion were not confirmed through histopathological observation. However, the illness was confirmed by mitochondrial DNA analysis to be a solitary neurocysticercosis case caused by the Asian genotype of Taenia solium.

Animals↗

PubMed2004

Cysticercosis: IgG-ELISA evaluations of peak1 antigen and <30 kDa antigen of delipidized extract of Taenia solium metacestodes.

The antigenicity of ether-delipidized Taenia solium metacestode extract (DLPAg) was investigated by IgG-ELISA. The antigen showed higher antigenicity than that of non-delipidized antigen (NDLPAg). Then the DLPAg was subjected to Sephacryl S-200 gel chromatography and a partially purified antigen (DLPP1Ag) was identified as the promised antigen by IgG-ELISA using 25 sera from cysticercosis cases, 177 cases of 24 heterologous infections, and healthy controls. Sensitivity was 52% and specificity was 91.8% at the cut-off value (X + 7SD), 0.399. Cross-reactivity occurred with 17 cases of eight diseases: cystic echinococcosis (7/11), taeniasis (1/16), gnathostomiasis (2/8), strongyloidiasis (1/12), angiostrongyliasis (1/12), paragonimiasis heterotremus (2/15), opisthorchiasis (1/9) and fascioliasis (2/7). When DLPP1Ag was fractionated through Ultra free centrifugal tube (retained 30 kDa) and Amicon (PM10), MWCOP1Ag (<30-10> kDa) was obtained; the antigen showed better results than DLPP1Ag with 88% sensitivity and 95.6% specificity at the cut-off value (X + 4SD), 0.264. Nine cases of six diseases cross-reacted with this antigen: cystic echinococcosis (2/11), gnathostomiasis (2/8), trichinellosis (2/12), toxocariasis (1/5), schistosomiasis (1/6), and fascioliasis (1/7). MWCOP1Ag gave higher sensitivity than that of DLPP1Ag but some cross-reactivity occurred.

Animals↗

PubMed2003

Human Taeniasis and cysticercosis in Asia.

CONTEXT: Human Taeniasis caused by the pork, Taenia solium, or beef, T saginata, tapeworm arises after eating pork or beef contaminated with metacestodes, the larval stage of these parasites. Taeniasis with T solium can lead to neurocysticercosis and threaten others by accidental ingestion of eggs released from asymptomatic Taeniasis patients. The 2003 World Health Assembly declared that T solium is of worldwide public-health importance, and that it is an eradicable parasitic disease worldwide. Adult taeniid tapeworms expelled from people in almost all Asian countries appeared to be T saginata (the so-called Asian Taenia), even though they ate pork. The organism is now named T asiatica, and has been found in Taiwan, Korea, China, Vietnam, and Indonesia. But it has been difficult to differentiate T saginata from beef and Asian Taenia from pork. STARTING POINT: Marshall Lightowlers and colleagues (Int J Parasitol 2003; 33: 1207-17) recently demonstrated that recombinant oncosphere vaccines against several taeniid cestodes, including T ovis, T saginata, T solium, and Echinococcus granulosus, are highly effective. Protection was almost 100%, in the laboratory and in the field. These researchers found several common features, including a predicted secretory signal sequence, and one or two copies of a fibronectin type III domain, each encoded by separate exons within the associated gene. WHERE NEXT? Molecular and immunological techniques, including vaccine research and development of animal models for differentiation of taeniid species in humans, have greatly advanced over the past decade. The clinical importance of infections by these taeniids, including T asiatica, in humans, and the potential for cysticercosis attributable to T asiatica in humans, needs further study.

Animals↗

PubMed2003

Development of Em18-immunoblot and Em18-ELISA for specific diagnosis of alveolar echinococcosis.

Extensive experience has documented that Em2(plus)-ELISA, Em10-ELISA and Em18-immunoblot and Em18-ELISA are reliable serologic methods for detection of alveolar echinococcosis (AE) caused by the metacestodes of Echinococcus multilocularis. Among these, tests based on detection of antibodies to the specific Em18 antigen, either immunoblot or ELISA, appears to be the most specific for AE. Between 90 and 97% of AE cases with characteristic hepatic lesions detectable by image analysis have been positive in Em18-serology. In contrast Antigen B (8 kDa)-immunoblot is the most sensitive for all forms of echinococcosis, although it can not differentiate AE from cystic echinococcosis (CE). Primary serologic screening for echinococcosis, especially for CE using hydatid cyst fluid of Echinococcus granulosus appears to be highly sensitive in endemic areas. Glycoproteins (GPs) purified from cyst fluid of Taenia solium are highly specific for diagnosis of T. solium neuorcysticercosis (NCC). Using currently available antigens it is not difficult to differentiate these three larval cestodiases serologically. We recommend that (1) primary screening of CE in endemic areas should be carried out using hydatid cyst fluid of E. granulosus prepared from cysts in either sheep, human or mouse for immunoblot and from sheep or mouse for ELISA, (2) both primary screening and confirmation of AE in endemic areas should be carried out using Em18-ELISA, Em18-immunoblot or Em2(plus)-ELISA. Serodiagnosis in areas where both AE and CE are endemic, such as in China, should be carried out as a combination of (1) and (2), and (3) serology of NCC should be carried out using GP-ELISA or GP-immunoblot. All samples showing antibody to Em18 are exclusively from echinococcosis cases. There have been no false positive test reactions with sera from other diseases. Strongest Em18 responders are all from patients with AE but some weaker responses may be found in sera of persons with advanced complex lesions of CE. These highly reliable serodiagnostic methods using native, recombinant and synthetic antigens are briefly summarized and experiences with these methods in Japan is reviewed. We believe that use of these specific antigens in screening and confirmation programs for AE in Japan will improve specificity and reduce the confusion, anxiety and expense in persons whose sera give false positive reactions with crude echinococcal antigens.

Animals↗

PubMed2003

Multiple genotypes of Taenia solium--ramifications for diagnosis, treatment and control.

Mitochondrial DNA sequences of Taenia solium have fully been analyzed. Analysis of the full length of cytochrome c oxidase subunit 1 (1620 bp) and cytochrome b (1068 bp) genes of T. solium, isolated from Asia (China, Thailand, Indonesia and India), from Latin America (Mexico, Ecuador, Bolivia, Peru and Brazil) and from Africa (Tanzania, Mozambique and Cameroon), has revealed that the two phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia formed a single cluster, whereas those from Latin America combined with those from Africa to form an additional cluster. It was estimated that these two genotypes emerged approximately 4-8 x 10(5) years ago. These results together with recent study of the ancient of human taeniid cestodes emerged several MYA in Africa, historical data on swine domestication, distribution of pigs and colonization patterns suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that T. solium of another origin independently spread in Asian countries, perhaps from China. Why did not T. solium of European origin invade or spread into Asia during the colonial age? Analysis of T. solium distribution must include other Taenia species, especially T. saginata and T. asiatica, which can not be differentiated from each other morphologically. BESS T-base analysis for differentiation of all human Taenia species including the two genotypes of T. solium, and T. saginata and T. asiatica has also been characterized. BESS T-base analysis differentiates African isolates from Latin American isolates as well but more samples should be analyzed for obtaining conclusive evidence for the latter. Serological analysis of cyst fluid of T. solium cysticerci obtained in China and Indonesia and from Mozambique and Ecuador indicates geographical differences in their banding patterns. These differences are discussed in the light of possible differences in pathology of T. solium worldwide. As it has been speculated that the ancient T. solium emerged several million years ago in Africa, it is necessary to analyze more isolates from Africa. Such working hypothesis may be evaluated combined with symptomatology and serology when we get additional DNA data from such areas, since there are some varieties of manifestation of neurocysticercosis with or without subcutaneous cysticercosis and of antigens of cyst fluid of T. solium from Asia and from Africa and/or America. Transfer of techniques of molecular identification and sero- and immuno-diagnoses between researchers and technicians from endemic countries using their own materials should be promoted with the aim of better international cooperation for the control of cysticercosis.

Animals↗

PubMed2003

Isolation of polymorphic microsatellite loci from the tapeworm Echinococcus multilocularis.

Two microsatellites were isolated from a genomic library of Echinococcus multilocularis. The microsatellites, designated EMms1 and EMms2, consist of tandem repeats of CAC-trinucleotide unit. Southern blot hybridization suggests that each of them is a single locus. Using fox-derived wild tapeworms (N=104), PCR-amplification of microsatellites was performed to assess the usefulness of these loci. We found four alleles of EMms1 and two alleles of EMms2. The heterozygosities observed were 10.6% in EMms1 and 7.7% in EMms2. The result suggests that both selfing and outcrossing occur in the adult stage of E. multilocularis.

Animals↗

PubMed2003

Evaluation of use of recombinant Em18 and affinity-purified Em18 for serological differentiation of alveolar echinococcosis from cystic echinococcosis and other parasitic infections.

To further evaluate recombinant Em18 antigen (rEm18) for immunodiagnosis of human alveolar echinococcosis, 208 serum samples were examined by enzyme-linked immunosorbent assay (ELISA). To comparatively assess the results of rEm18-ELISA, ELISA and immunoblot analysis with two affinity-purified native antigens were also performed with 45 selected serum samples. The results indicate that rEm18 is highly useful for serodiagnosis.

Animals↗

PubMed2003

The mitochondrial genome of the tapeworm Taenia solium: a finding of the abbreviated stop codon U.

The complete nucleotide sequence of the tapeworm Taenia solium mitochondrial DNA (mtDNA) has been determined. The sequence is 13,709 base pairs in length and contains 36 genes (12 for proteins involved in oxidative phosphorylation, 2 for ribosomal RNAs, and 22 for transfer RNAs). The gene content and organization of the T. solium mtDNA are identical to those of other taeniid mtDNAs. All genes are transcribed in the same direction, and all protein-coding genes appear to initiate with the AUG or GUG codon. In a gene for NADH dehydrogenase subunit 1, the abbreviated stop codon U was confirmed for the first time in flatworm mtDNAs.

Animals↗

PubMed2003

Short report: Identification of Echinococcus species from a yak in the Qinghai-Tibet plateau region of China.

The species identification of an echinococcal lesion in the liver of a yak in the Qinghai-Tibet plateau region of China, where both Echinococcus granulosus and E. multilocularis are present, was difficult to determine because of the atypical appearance of the lesion. Polymerase chain reaction-based mitochondrial genotyping allowed us to discriminate the Echinococcus species. Nucleotide sequences of the cytochrome c oxidase subunit 1 (cox1) and cytochrome b (cytb) genes amplified from the echinococcal lesion demonstrated that the yak was infected with the E. granulosus G1 genotype (sheep strain).

Animals↗

PubMed2003

Magnetic resonance imaging and immunoblot analyses in rats with experimentally induced cerebral alveolar echinococcosis.

The early stage of experimentally induced secondary cerebral alveolar echinococcosis (AE) in rats was investigated by use of magnetic resonance imaging (MRI) and immunoblot (western blot) analyses. Thirty-six female Wistar rats (6 to 8 weeks old) were injected intracranially with a 10% homogenate of echinococcal larval tissues in which the concentrations of microvesicles and protoscolices were estimated to be 3.8 and 1.5 x 10(4)/ml, respectively. To observe the fine structure of the rat brain, MRI was performed under a high magnetic field of 7.05 T. Histologic examination also was performed. The T2-weighted MR images revealed a hyperintense region in the cerebral cortex at two weeks after injection of the homogenate. At three weeks after injection, this region was found to have cysts on the basis of results of histologic examination. Signal-void regions corresponding to hyperplasia and the subsequent calcification of the cuticle layer at six and 13 weeks after injection, respectively, were observed in T2-weighted and proton density MR images. On the other hand, at nine weeks after injection, AE was discernible by use of western blot analysis of sera with antibodies of two epitopes (Em18 and Em16) of E. multilocularis. Using this secondary cerebral AE animal model, it was concluded that the MRI method was suitable for early detection of secondary cerebral AE.

Animals↗

PubMed2002

The complete mitochondrial DNA sequence of the cestode Echinococcus multilocularis (Cyclophyllidea: Taeniidae).

The 13,738 bp mitochondrial DNA from the cestode Echinococcus multilocularis has been sequenced. It contains two major noncoding regions and 36 genes (12 for proteins involved in oxidative phosphorylation, two for rRNAs and 22 for tRNAs) but a gene for ATPase subunit 8 is missing. All genes are transcribed in the same direction. Putative secondary structures of tRNAs indicate that most of them are conventional clover leaves but the dihydrouridine arm is unpaired in tRNA(Ser(AGN)), tRNA(Ser(UCN)), tRNA(Arg) and tRNA(Cys). The base composition at the wobble positions of fourfold degenerate codon families is highly biased toward U and against C.

Journal Article↗

PubMed2002

Usefulness of hydatid cyst fluid of Echinococcus granulosus developed in mice with secondary infection for serodiagnosis of cystic Echinococcosis in humans.

The aim of this work was to assess the usefulness of hydatid cyst fluid (HCF) of Echinococcus granulosus, obtained from mice experimentally infected with hydatid cyst tissue homogenates, for the serodiagnosis of cystic echinococcosis (CE) in humans. The sensitivity and specificity of HCF obtained from mice for the detection of immunoglobulin G (IgG) antibodies in the sera of CE patients were compared with those of HCF from sheep and/or from a human CE patient by using immunoblotting (IB) and an enzyme-linked immunosorbent assay (ELISA). HCFs obtained from three different host species all were highly useful for immunoblotting, and sera from 19 (95%) of 20 CE patients equally recognized the antigen B subunit (approximately 8 kDa). HCF from mice showed a cross-reaction with 9 of 20 alveolar echinococcosis (AE) sera (45%), whereas HCFs from two other host species cross-reacted with 14 of the AE sera (70%). Although 2 (10%) of 20 sera from neurocysticercosis (NCC) patients were false positive with HCF from both sheep and humans, none of these sera showed a positive reaction with HCF from mouse origin. ELISAs with HCFs from both mouse and sheep origins detected all 20 CE and AE sera; however, these ELISAs showed 45% (9 of 20) and 60% (12 of 20) false-positive reactions with 20 NCC sera, respectively. The presence of nonspecific human IgG in HCF obtained from a CE patient prevented us from applying it to the ELISA. HCF of E. granulosus, obtained from laboratory mice with a secondary infection with hydatid cyst tissue homogenates, appears to be highly useful for the serodiagnosis of CE in humans and may be useful in domestic animals.

Animals↗

PubMed2002

DNA differential diagnosis of human taeniid cestodes by base excision sequence scanning thymine-base reader analysis with mitochondrial genes.

For DNA differential diagnosis of human Taenia cestodes, a base excision sequence scanning thymine-base method using the cytochrome c oxidase subunit I and cytochrome b genes as targets was used. The characteristic thymine-base peak profiles provide four distinct types, unique for T. saginata, T. asiatica, and two genotypes of T. solium. This approach provides a useful tool for the identification and diagnosis of human taeniid cestodes without DNA sequencing if nucleotide sequence databases are available.

Cytochrome b Group↗

PubMed2002

Evaluation of an enzyme-linked immunosorbent assay (ELISA) with affinity-purified Em18 and an ELISA with recombinant Em18 for differential diagnosis of alveolar echinococcosis: results of a blind test.

Alveolar echinococcosis (AE) is the most potentially lethal parasitic zoonosis of the nontropical areas in the northern hemisphere, where cystic echinococcosis (CE) is also endemic. Both AE and CE are highly endemic in China, and both serologic detection of echinococcosis, either AE or CE, and differentiation of AE from CE are crucial problems. Evaluation of Western blot analysis (WB) and enzyme-linked immunosorbent assay (ELISA) for the Em18 antigen, using affinity-purified and recombinant Em18, was carried out "blindly" using 60 human sera from patients diagnosed in France. The results were compared with those obtained using a commercially available Echinococcus WB immunoglobulin G (IgG) kit developed in France. The Em18 WB and Echinococcus WB IgG showed very similar results for detection of AE. Both affinity-purified Em18 or a recombinant Em18 WB and Echinococcus WB IgG seem useful for identification of AE, and the latter seems appropriate for both AE and CE, whereas affinity-purified Em18 ELISA and the newly developed recombinant Em18 ELISA appear to be suitable for detection of AE, especially for epidemiological surveys.

Animals↗

PubMed2002

Alveolar echinococcosis: characterization of diagnostic antigen Em18 and serological evaluation of recombinant Em18.

The Echinococcus multilocularis protein Em18 is one of the most promising antigens for use in serodiagnosis of alveolar echinococcosis in human patients. Here we identify an antigenic relationship between Em18 and a 65-kDa immunodominant E. multilocularis surface protein previously identified as either EM10 or EmII/3. The NH(2)-terminal sequence of native Em18 was determined, revealing it to be a fragment of EM10. Experiments were undertaken to investigate the effect of proteinase inhibitors on the degradation of EM10 in crude extracts of E. multilocularis protoscoleces. Em18 was found to be the product of degradation of EM10 by cysteine proteinase. A recombinant Em18 (RecEm18, derived from (349)K to (508)K of EM10) was successfully expressed by using Escherichia coli expression system and then evaluated for use in serodiagnosis of alveolar echinococcosis. RecEm18 was recognized by 27 (87.1%) and 28 (90.3%) of 31 serum samples from clinically and/or pathologically confirmed alveolar echinococcosis patients by enzyme-linked immunosorbent assay and immunoblotting, respectively. Of 33 serum samples from cystic echinococcosis patients, 1 was recorded as having a weak positive reaction to RecEm18; however, none of the serum samples which were tested from neurocysticercosis patients (n = 10) or healthy people (n = 15) showed positive reactions. RecEm18 has the potential for use in the differential serodiagnosis of alveolar echinococcosis.

Amino Acid Sequence↗