Biomedical subjects

S Ichiyama

Publications and source records attributed to S Ichiyama.

At least 55 records · Page 3Linked to original sources

PubMed1998

Diagnostic value of the Amplicor PCR assay for initial diagnosis and assessment of treatment response for pulmonary tuberculosis.

We evaluated the Amplicor PCR assay as an initial diagnostic tool on the basis of clinical diagnosis, and assessed this assay as a follow-up test for patients with pulmonary tuberculosis during chemotherapy. Of the 208 specimens from 155 patients who were bacteriologically and/or clinically diagnosed with active tuberculosis before chemotherapy, 144 were Amplicor PCR-positive (sensitivity, 69.2%), which was equal to the results of culturing. Among 89 specimens which showed positive results by smear and culturing, the Amplicor PCR assay detected 87 (97.8%), whereas among 55 specimens which showed smear-negative but culture-positive results, the Amplicor PCR assay detected 46 (83.6 %)(P= 0.003). No false positive results were found in the two systems (specificity, 100%, 120/120). The Amplicor PCR assay was also evaluated as a follow-up test using 926 specimens from 207 patients receiving active tuberculosis chemotherapy. Among 433 specimens which showed Amplicor-PCR positive, 222 (51.3%) were culture-negative. On the other hand, among 233 culture-positive specimens, only 12 (5.2%) were Amplicor PCR-negative. Therefore, this assay is useful for the rapid diagnosis of tuberculosis. The duration of Amplicor PCR-positive after culture-negative conversion was significantly associated with the presence of cavitary lesion, smear-positive specimens before treatment, and smear-positive specimens with negative cultures during chemotherapy.

Antitubercular Agents↗

PubMed1998

Heterogeneity of phenotypic and genotypic traits including organic-acid resistance in Escherichia coli O157 isolates.

We undertook an epidemiologic study for the sensitivity of both Shiga-like toxin (Slt)-producing Escherichia coli (STEC) O157 and non-STEC O157 strains isolated from different patients with diarrhea to hydrochloric acid (HCl) and organic acids such as acetate, propionate, butyrate and lactate, and other pathogenic factors. The E. coli O157 isolates examined showed a wide variety of organic-acid susceptibility patterns. E. coli O157 isolates resistant to HCl or acetate were found more frequently than those resistant to other organic acids. These isolates also showed diverse pathogenicity patterns for the presence of the virulence genes, antibiotic susceptibility and plasmid profile.

Acids, Acyclic↗

PubMed1998

Effect of gene transfer of tumor necrosis factor receptors into human lung carcinoma cell line.

The human lung adenocarcinoma cell line A549 is known to be resistant to tumor necrosis factor alpha (TNF-alpha)-mediated tumor cell lysis in spite of the expression of 55 kDa TNF receptor (TNF-R55) mRNA and its cell surface protein. In this study, we investigated the mechanism of TNF-alpha resistance and the role of two types of TNF receptors (TNF-R55 and TNF-R75 (75 kDa TNF receptor)). TNF-R55 or TNF-R75 cDNA was transfected into A549 cells. In addition, a C-terminal deletion mutant of TNF-R75 which lacks the intracellular domain of TNF-R75 was also transfected into A549 cells. We assessed the TNF-alpha-mediated tumor cell lysis of these transfected clones, and found that the cytotoxic effect increased in transfected clones highly expressing TNF- R55, but not in low-expression clones. As for TNF-R75, the cytotoxic effect of TNF-alpha was observed in TNF-R75-transfected clones even when expression was low. Furthermore, the cytotoxic effect was also observed in clones transfected with the deletion mutant of TNF-R75, as well as the complete TNF-R75. These results indicate that a certain level of expression of TNF-R75 is necessary for obtaining TNF-alpha-mediated tumor cell lysis in the absence of TNF-R75. On the other hand, the expression of TNF-R75 strongly induces TNF-alpha-mediated cytotoxicity through TNF-R55 in the absence of an intracellular signal via TNF-R75.

Adenocarcinoma↗

PubMed1998

Carbapenem-induced endotoxin release in gram-negative bacterial sepsis rat models.

The carbapenem-induced endotoxin release was evaluated using experimental models of gram-negative bacterial sepsis in Wistar rats. Infections with Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris and Proteus mirabilis resulted in an increase of the plasma endotoxin concentration after treatment with ceftazidime and carbapenems including imipenem, panipenem, meropenem and biapenem. Except for P. aeruginosa, the plasma endotoxin concentrations after carbapenem treatment were significantly lower than those after ceftazidime treatment. It is noteworthy that treatment of P. aeruginosa sepsis with meropenem or biapenem induced significantly more endotoxin release than other carbapenems and the endotoxin concentrations induced by these carbapenems reached those of ceftazidime treatment. The plasma endotoxin concentrations appeared to correlate with the reduction of platelet counts and the elevation of both glutamic oxaloacetic transaminase and glutamic pyruvic transaminase values.

Animals↗

PubMed1998

Differential normalization of mucosal interleukin-8 and interleukin-6 activity after Helicobacter pylori eradication.

There is differential resolution of mucosal infiltration with neutrophils and mononuclear cells following successful Helicobacter pylori eradication. We investigated the effects of H. pylori eradication on mucosal interleukin-8 (IL-8) and IL-6 activity in relation to the resolution of H. pylori-associated gastritis. Eighty-one duodenal ulcer patients with H. pylori infection received dual- or triple-treatment eradication therapy, and mucosal biopsy specimens obtained at the initial and follow-up endoscopic examinations were cultured in vitro for 24 h. The levels of IL-8 and IL-6 were measured by enzyme-linked immunosorbent assays. In the 42 patients in whom H. pylori eradication failed, there was little change in the numbers of neutrophils and mononuclear cells infiltrating the mucosa and in IL-8 and IL-6 activity. In the 39 patients in whom H. pylori was eradicated, there was normalization both in the numbers of infiltrating neutrophils and in mucosal IL-8 activity, which was evident within 1 month following therapy. In contrast, there was a gradual resolution of mononuclear cell infiltration over a 6-month period, accompanied by a gradual normalization in IL-6 levels. Addition of H. pylori to cultures of mucosal tissues induced a significant increase in IL-8 activity in both uninfected control subjects and patients from whom H. pylori was eradicated. However, this introduction yielded a significant increase in IL-6 activity only in the latter group. This study indicates a dichotomy in the changes of mucosal IL-8 and IL-6 activity after H. pylori eradication. The rapid normalization of IL-8 after H. pylori eradication and the ability of H. pylori cells to stimulate IL-8 in control tissues indicate that IL-8 induction is a part of the innate (nonimmune) responses to this organism. In contrast, the results of experiments analyzing IL-6 activity in cultured mucosal tissues suggest that the gradual resolution of mucosal IL-6 activity and mononuclear infiltration after successful eradication observed in vivo may reflect gradually diminishing residual immune responses against H. pylori.

Adult↗

PubMed1998

Evaluation of a membrane filter assay system, Ortho HCV Ab Quick Pack, for detection of anti-hepatitis C virus antibody.

A simple membrane immunoassay assay system, Quik Pack, for the detection of hepatitis C virus antibody was compared with two enzyme-linked immunosorbent assays (ELISAs) in a study of 600 serum samples. Quik Pack exhibited excellent sensitivity and specificity: 96.0 and 99.7%, respectively, versus the ELISA-2 and 99.7 and 99.4%, respectively, versus the ELISA-3.

Enzyme-Linked Immunosorbent Assay↗

PubMed1998

Polymerase chain reaction of pleural biopsy specimens for rapid diagnosis of tuberculous pleuritis.

SETTING: Government-administered regional teaching hospital. OBJECTIVE: To improve timeliness and sensitivity of laboratory diagnosis of tuberculous pleuritis. DESIGN: We applied polymerase chain reaction (PCR) to detect DNA (IS6110) specific for Mycobacterium tuberculosis complex in pleural biopsy specimens. RESULTS: Of 28 patients with pleural disease, 11 were diagnosed by microbiology (smear/culture of sputum or pleural fluid) with tuberculous pleuritis, eight were diagnosed with tuberculous pleuritis by histology (of pleural biopsies) and/or clinical presentation, and nine were diagnosed with carcinomatous pleuritis. Seventeen of the patients' pleural biopsies were PCR positive. Based on microbiological results, the sensitivity of the PCR assay was 100% (11/11). On the other hand, based on the results of the histological and clinical data, sensitivity and specificity of the PCR results were 89% (17/19) and 100% (9/9), respectively. CONCLUSION: PCR of pleural biopsy specimens can be a useful method when employed in combination with microbiological and histological examinations of pleural biopsy for rapid diagnosis of tuberculous pleuritis.

Adult↗

PubMed1997

Prevalence of the speA2 and speA3 alleles in Streptococcus pyogenes isolated from TSLS patients in Japan.

More than 100 cases have been identified as streptococcal toxic shock-like syndrome (TSLS) in Japan, since the first case was reported in 1993. Of 26 S. pyogenes isolates associated with TSLS, 69% were M-types 1 and 3. This study focused on speA alleles which were carried by all M-type 1 and 3 isolates and isolates of some other M-types, irrespective of sources. We sequenced the nucleotides of the relevant region of the speA allele in all of these isolates. Consistent with other reports, these M-type 1 and 3 isolates carried the speA2 and speA3 alleles, respectively. Our results indicate that these two speA alleles, which were prevalent world-wide have been disseminating in Japan.

Alleles↗

PubMed1997

Investigation of nosocomial infection caused by arbekacin-resistant, methicillin-resistant Staphylococcus aureus.

An outbreak of coagulase VII-producing, arbekacin (ABK)-resistant, methicillin-resistant Staphylococcus aureus (MRSA) occurred between September 1994 and December 1995, involving five different wards. Twenty-one patients developed skin, wound, drainage, or respiratory tract colonization with coagulase VII-producing, (ABK)-resistant MRSA. Phenotypic characteristics (production of enterotoxin and TSST-1, antimicrobial susceptibility) and molecular-typing procedure (plasmid DNA profile, pulsed-field gel electrophoresis [PFGE] and arbitrarily primed polymerase chain reaction [AP-PCR] of chromosomal DNA) in isolated strains were compared. Plasmid analysis identified four different profiles and 19 of 22 strains recovered had identical patterns. PFGE of chromosomal DNA identified three different subtypes and 18 (81.8%) isolates shared the same subtype. AP-PCR also demonstrated that most strains had the same phenotypic characteristics. Although traditional epidemiological methods; for example, coagulase typing, plays a central role in hospital infection control, combination of plasmid DNA profile, AP-PCR, and PFGE may prove to be a particularly informative means of tracking the nosocomial spread of MRSA.

Adult↗

PubMed1997

A clinical and bacteriologic investigation of invasive streptococcal infections in Japan on the basis of serotypes, toxin production, and genomic DNA fingerprints.

In a survey of invasive streptococcal infections in Japan, we analyzed isolates of Streptococcus pyogenes collected between 1992 and 1994. Genomic DNA fingerprints produced by pulsed-field gel electrophoresis (PFGE) were compared by computer-assisted analysis. Conventional serologic M types were subdivided into PFGE types showing close genetic similarity. Among the 42 isolates from patients with invasive diseases, 16 PFGE types were identified and genetic diversity was clearly demonstrated. Identical fingerprints were observed in both invasive and noninvasive isolates. Only 43% of invasive isolates produced streptococcal pyrogenic exotoxin A (SPE A), and 31% did not contain the speA gene. These findings suggest that the dissemination of a specific clone is not sufficient to explain all cases of these diseases in Japan and pose a question as to the role of SPE A as a major virulent factor. Bacterial factors other than SPE A and host factors should be considered in evaluation of the pathogenesis of the diseases.

Antibodies, Bacterial↗

PubMed1997

Transmission of Streptococcus pyogenes causing toxic shock-like syndrome among family members and confirmation by DNA macrorestriction analysis.

Streptococcus pyogenes can cause severe infections, such as toxic shock-like syndrome (TSLS). The transmission and pathogenesis of TSLS are poorly understood, and information is needed to develop prevention strategies. Four cases were identified in which the organism was transmitted among patients with TSLS and their family members. DNA macrorestriction endonuclease analysis using pulsed-field gel electrophoresis demonstrated the spread of S. pyogenes clones that caused TSLS among the family members. Although 14 persons related to the case-patients experienced only colonization or self-limited disease, 3 developed invasive infections (pneumonia, severe pharyngitis requiring hospitalization, and puerperal sepsis). These findings indicate that antimicrobial prophylaxis for close contacts of patients with TSLS should be considered and reinforce the need for further studies on epidemic control of TSLS.

Adult↗

PubMed1997

Mucosal chemokine activity in Helicobacter pylori infection.

We examined secretion, mRNA expression, and histologic localization of interleukin-8 (IL-*) and growth-related gene product-alpha (GRO alpha) in the Helicobacter pylori-infected gastric antral mucosa. Antral biopsies were obtained from an area of endoscopically intact mucosa. Significantly higher levels of IL-8 and GRO alpha were secreted in organ cultures from patients with H. pylori infection, and their elevation was prominent in patients with duodenal ulcer. There was a significant association between these alpha-chemokine levels and histologic grades of activity, inflammation, and H. pylori density. In fresh antral biopsies, IL-8 and GRO alpha mRNA expression was detected more frequently in H. pylori-infected patients compared with those without infection. Immunofluorescence microscopy showed localization of IL-8 and GRO alpha proteins in gastric epithelial cells and infiltrating CD68+ macrophages. In the chemotaxis assay, a significant positive correlation was found between neutrophil migration induced by the organ culture supernatants and their contents of IL-8 and GRO alpha. After H. pylori eradication, a significant decrease was observed in IL-8 and GRO alpha levels detected in organ cultures. In conclusion, mucosal alpha-chemokine activity correlates well with histologic severity of H. pylori-associated antral gastritis and can be used to predict the effects of H. pylori eradication therapy.

Adult↗

PubMed1997

Nosocomial spread of cephem-resistant Escherichia coli strains carrying multiple Toho-1-like beta-lactamase genes.

Escherichia coli HKY56, which demonstrated resistance to various beta-lactams except carbapenems, was isolated from the throat swab of an inpatient in 1994. Conjugal transfer of cephem resistance from HKY56 to E. coli CSH2 was not successful. Three cefotaxime-resistant E. coli clones harboring plasmid pMRE001, pMRE002, or pMRE003, each of which carried a 3.4-, 5.8-, or 6.2-kb EcoRI fragment insert, respectively, were obtained from HKY56. Although restriction analysis suggested their different origins, these clones showed similar profiles of resistance to various beta-lactams. The sequence of 10 amino acid residues at the N terminus of beta-lactamase purified from E. coli HB101(pMRE001) was identical to that of Toho-1. This Toho-1-like beta-lactamase-1 (TLB-1) was able to hydrolyze cefoperazone and cefotaxime efficiently, but it failed to hydrolyze cephamycins. A Toho-1-specific DNA probe was hybridized with three distinct EcoRI fragments derived from the chromosomal DNA of strain HKY56, and these fragments corresponded to DNA inserts carried by pMRE001, pMRE002, and pMRE003, respectively. PCR and Southern hybridization analysis suggested that all six cephem-resistant E. coli strains, strains HKY273, HKY285, HKY288, HKY305, HKY316, and HKY335, which were isolated in 1996 at the same hospital where strain HKY56 had been isolated, also possessed multiple Toho-1-like beta-lactamase (TLB) genes, and the hybridization patterns obtained with the Toho-1-specific probe were quite similar among these six isolates. The DNA fingerprinting patterns observed by pulsed-field gel electrophoresis revealed that among the E. coli isolates tested, all isolates except HKY56 possessed a similar genetic background. These findings suggested that E. coli strains that carry chromosomally multiplied TLB genes may have been proliferating and transmitted among patients in the same hospital.

Carbapenems↗

PubMed1997

Mechanism of nitric oxide-dependent killing of Mycobacterium bovis BCG in human alveolar macrophages.

We demonstrated that products of the L-arginine-dependent pathway of human alveolar macrophages (AM) effectively kill the Mycobacterium bovis bacillus Calmette-Guérin (BCG) in vitro. The formation of products was triggered by inoculation with BCG itself. Many reports have shown that activated rodent AM could produce an amount of nitric oxide (NO) sufficient to suppress the growth of mycobacteria. However, there have been no definitive results as to whether human AM might have the NO-dependent mechanism for the killing of mycobacteria. Therefore, we have undertaken some experiments to answer this question. Immunofluorescence assays showed an increased production of inducible nitric oxide synthase (iNOS) and peroxynitrite in BCG-inoculated AM from patients with pulmonary fibrosis. Reverse transcriptase-PCR also revealed the higher expression of iNOS-coding mRNA. Colony assays demonstrated that these human AM effectively killed BCG in their cytoplasm. However, treatment of AM with N(G)-monomethyl-L-arginine monoacetate resulted in markedly reduced killing activity. These results clearly show that BCG-induced NO and its reactive product with the oxygen radical peroxynitrite could play an important role in the killing of BCG in human AM.

Bronchoalveolar Lavage↗

PubMed1997

Diagnostic value of the strand displacement amplification method compared to those of Roche Amplicor PCR and culture for detecting mycobacteria in sputum samples.

We compared the ability of the semiautomated BDProbeTec-SDA system, which uses the strand displacement amplification (SDA) method, with that of the Roche Amplicor-PCR system and the Septi-Chek AFB culture system to directly detect Mycobacterium tuberculosis complex (MTB) and other mycobacteria in sputum samples. A total of 530 sputum samples from 299 patients were examined in this study. Of the 530 samples, 129 were culture positive for acid-fast bacilli with the Septi-Chek AFB system; 95 for MTB, 29 for M. avium-M. intracellulare complex (MAC), and 5 for other mycobacteria. The BDProbeTec-SDA system detected 90 of the 95 samples culture positive for MTB (sensitivity, 94.7%), and the Amplicor-PCR system detected 85 of the 95 samples culture positive for MTB (sensitivity, 89.5%). The specificity of each system, based on the clinical diagnosis, was 99.8% for SDA and 100% for PCR, respectively. Among the 29 samples culture positive for MAC, the BDProbeTec-SDA system detected MAC in 24 samples (sensitivity, 82.8%), whereas the Amplicor-PCR system detected MAC in 23 samples (sensitivity, 79.3%). The specificities of the systems were 98.3 and 100%, respectively. The high degrees of sensitivity and specificity of the BDProbeTec-SDA system suggest that it should be very useful in clinical laboratories for the rapid detection of mycobacteria in sputum samples.

Bacteriological Techniques↗

PubMed1997

Large-restriction-fragment analysis of Mycobacterium kansasii genomic DNA and its application in molecular typing.

Large-restriction-fragment (LRF) polymorphisms in Mycobacterium kansasii isolates from 84 patients with bronchopulmonary infections in Japan between the 1960s and 1995 were studied by pulsed-field gel electrophoresis (PFGE). Chromosomal fragments digested with VspI were most suitable for PFGE separation of 16 to 21 fragments of between 40 and 550 kbp. All 84 isolates and the type strain M. kansasii ATCC 12478 were successfully typed by LRF analysis with VspI digestion. Twenty-one distinctive LRF types were identified, and the LRF patterns tested over time were reproducible and stable. A computer-assisted dendrogram of the percent similarity demonstrated that isolates of 18 LRF types had relatively close genetic relatedness, while isolates of the remaining 3 types showed divergence. Sequence analysis of the 16S rRNA gene in the isolates showing divergent genetic relatedness revealed a sequence identical to that of a previously reported subspecies of M. kansasii. In the Chugoku district of Japan, 11 cases of M. kansasii infection which occurred in workers in a coastal industrial zone between 1982 and 1993 were caused by one particular strain tentatively named LRF type M. When both detailed demographic data for the patients and ecologic data for the M. kansasii isolates are obtained, LRF typing may be of potential use for investigating the source and transmission of M. kansasii infection.

Bacterial Typing Techniques↗

PubMed1997

Determination of anti-streptolysin O antibody titer by a new passive agglutination method using sensitized toraysphere particles.

We developed a new method for determining the anti-streptolysin O (ASO) titer on the basis of a passive agglutination reaction. This new method uses Toraysphere particles sensitized with streptolysin O. This method was used to measure the ASO titer in 130 serum samples (from 31 patients with post-streptococcal glomerulonephritis, 26 patients with group A streptococcal pharyngitis, 5 patients with scarlet fever, 29 patients with non-group A streptococcal pharyngitis, 20 healthy children, and 19 healthy adults). The results were compared with those obtained simultaneously by two conventional methods, the Rantz-Randall and the NA-Latex-ASL methods. The results obtained by the Toraysphere method showed an excellent correlation with those obtained by each conventional method (correlation coefficients, 0.932 for the Rantz-Randall method and 0.913 for the NA-Latex-ASL method). The performance of each method was evaluated with respect to the clinical and microbiological diagnoses for each patient. The sensitivity, specificity, positive predictive value, and negative predictive value for the Toraysphere method were 76, 84, 81, and 79%, respectively. The corresponding values for the Rantz-Randall method were 48, 78, 67, and 62%, respectively, while those for the NA-Latex-ASL method were 60, 82, 76, and 69%, respectively. Because the Toraysphere method is simple and reproducible, has a short reaction time, and has a clear-cut endpoint for the analysis, we recommend it for routine use in determining the ASO titer in the clinical microbiology laboratory.

Adolescent↗

PubMed1997

Exfoliative toxin detection using reversed passive latex agglutination: clinical and epidemiologic applications.

A rapid and simple method for detecting exfoliative toxin serotypes A and B from clinical isolates has been developed as a test kit (EXT-RPLA; Denka Seiken Co. Ltd., Niigata, Japan). This method is based on reversed passive latex agglutination. The detection limit of the EXT-RPLA observed for purified exfoliative toxin serotypes A and B was 1 ng/ml. We evaluated the clinical and epidemiologic uses of the EXT-RPLA. A total of 381 isolates of Staphylococcus aureus, 292 from various clinical specimens and 89 from the skin of dermatologic patients, were studied. The EXT-RPLA detected 19 exfoliative toxin producers, including 16 serotype A producers and 3 serotype B producers, but no double producers. The sensitivity and specificity of the EXT-RPLA were confirmed by the newborn mouse bioassay and a PCR assay for the structural genes for exfoliative toxin serotypes A and B (eta and etb, respectively). The overall positivity rate of exfoliative toxin producers was 5.0% (19 of 381), including 16 serotype A isolates and 3 serotype B isolates. Of the 89 isolates from the skin of dermatologic patients, 12 (13.5%) were positive for exfoliative toxin production. Only 2 (1.3%) of the 153 methicillin-resistant S. aureus isolates produced exfoliative toxin, while 17 (7.5%) of the 228 methicillin-sensitive isolates produced exfoliative toxin. The EXT-RPLA assay is a simple and reliable method for detecting exfoliative toxin, and we recommend its use for the rapid diagnosis of staphylococcal scalded skin syndrome. We also recommend its use for detection of this syndrome so that effective control measures can be taken against the spread of this syndrome.

Agglutination Tests↗