PubMed Health⌕ Search

Biomedical subjects

J Miyamoto

Publications and source records attributed to J Miyamoto.

At least 37 records · Page 2Linked to original sources
PubMed1997

A rapid drug susceptibility test for Mycobacterium tuberculosis using the hybridization protection assay.

The conventional drug susceptibility tests for Mycobacterium tuberculosis are time-consuming and the results are available only after 2-4 weeks. We have recently reported a new, simple and fast M. tuberculosis drug susceptibility test, using the hybridization protection assay (HPA), that allows the detection of isoniazid- or rifampicin-resistant strains of M. tuberculosis within 24 h of incubation. In the present study, the scope of application of our new test was extended to another two first-line antimycobacterial agents, namely ethambutol and streptomycin, and a quinolone antimicrobial agent, ciprofloxacin. The ethambutol-, streptomycin- and ciprofloxacin-resistance characteristics of M. tuberculosis were also delineated within 72 h of incubation with or without the drug. The results of our novel and rapid drug susceptibility test for M. tuberculosis were not only comparable to those determined by the conventional method, but became available within a few days of incubation. Our results also suggest that the drug susceptibility test using HPA might also be useful for detecting organisms resistant to antimicrobial agents other than antimycobacterials.

Anti-Infective Agents↗
PubMed1997

Rapid prediction of rifampin susceptibility of Mycobacterium tuberculosis.

We evaluated the relationship between rifampin (RIF) susceptiblility and amino acid substitution in rpoB gene of Mycobacterium tuberculosis and the usefulness of rpoB gene sequencing in the rapid prediction of RIF susceptibility of M. tuberculosis in clinical specimens. A total of 76 genetic alterations in the 69 bp core region of rpoB gene were detected in 74 of 130 M. tuberculosis strains. Examination of the correlation between the minimum inhibitory concentrations (MICs) of RIF and amino acid substitutions in the 69 bp core region of rpoB gene revealed that all 43 strains containing amino acid substitution with Leu or Trp in codon 531 showed RIF-resistant phenotypes, with MICs > or = 64 microg/ml. In contrast, a variable level of RIF susceptibility was observed among strains containing amino acid substitutions in either codon 516 or codon 526. In the clinical study, we tested 26 sputum samples, two gastric lavages, and one synovial fluid sample obtained from patients with tuberculosis. The RIF susceptibility predicted by direct rpoB sequencing was satisfactorily compatible with the results of the RIF-susceptibility test and the MICs of RIF against isolated organisms. Our results suggest that rpoB gene sequencing is useful for the detection of M. tuberculosis in clinical samples as well as the rapid prediction of RIF susceptibility of these strains.

Amino Acid Sequence↗
PubMed1997

[Relationship between streptomycin susceptibility and rpsL mutations of Mycobacterium tuberculosis strains].

The relationship between streptomycin (SM) susceptibility and rpsL mutations of Mycobacterium tuberculosis strains was studied. Of 18 clinically isolated SM-resistant M.tuberculosis strains, mutation was suspected in 9 strains (50%) with SM MICs of > or = 256 micrograms/ml by PCR-single strand conformation polymorphism targeting rpsL gene. On the other hand, using PCR-direct sequence method, amino acid substitution caused by single nucleotide point mutation in rpsL gene was demonstrated in 11 out of 18 strains (61%). The same amino acid substitution at codon 43 (Lys-->Arg) was observed in all 11 strains with SM MICs of > or = 256 micrograms/ml. In addition, PCR products obtained from these 11 strains could not be cut by a restriction enzyme, Mbo II, while H37Rv strain and the other 32 strains with SM MICs of < 256 micrograms/ml were cut into 2 fragments. In conclusion, our results suggest that highly SM-resistant M.tuberculosis strains with MICs of > or = 256 micrograms/ml could be rapidly and easily detected by the restriction enzymatic method.

Antibiotics, Antitubercular↗
PubMed1996

New drug susceptibility test for Mycobacterium tuberculosis using the hybridization protection assay.

We developed a novel method for early detection of drug-resistant strains of Mycobacterium tuberculosis by using the hybridization protection assay (HPA). The number of viable bacteria during the incubation period correlated well with the number of relative light units measured by the HPA. In addition, the relative light unit values of susceptible strains on the first, third and fifth days of incubation were significantly different from those of resistant strains for both isoniazid and rifampin. Our results suggest that after isolation of the organism from clinical specimens, drug-resistant strains of M. tuberculosis are accurately detected by the HPA even after 1 day of incubation with the drug.

Antibiotics, Antitubercular↗
PubMed1996

[Differential diagnosis of tuberculous pleurisy by the measurement of cytokine concentration in pleural effusion].

Pleural fluids obtained from 26 patients with tuberculous pleurisy (T-group), 11 with parapneumonic pleurisy (B-group) and 21 with malignant pleurisy (M-group) were tested for their biologic parameters and cytokine concentrations. 1) The average age of T-group was over 10 years lower than that of M-group with a statistically significant difference. 2) The average CRP value of B-group and the positivity on PPD skin test of T-group were higher than those of the other groups, respectively. 3) Yellowish pleural fluids were mainly observed in T- and B-group, while bloody pleural fluids were mostly seen in M-group with a statistically significant difference. The average total protein amount and adenosine deaminase value in pleural fluid significantly increased in T-group. The percentage of polymorphonuclear leukocytes showed a significant increase in B-group, while lymphocytes significantly increased in T-group with a statistically significant difference. 4) Although no significant difference in concentrations of IL-1 beta, IL-2, IFN-gamma and TNF-alpha in serum was noticed among the three groups, the average concentrations of IFN-gamma and TNF-alpha in pleural fluid in T-group were significantly higher than those in the other groups. 5) TNF-alpha-mRNA of mononuclear cells in pleural fluid was strongly expressed in 3 out of 11 patients of T-group, while no expression was observed in 6 patients of M-group. In conclusion, the measurement of concentrations of two kinds of cytokines in pleural fluid, IFN-gamma and TNF-alpha, may be clinically useful for the differential diagnosis of tuberculous pleurisy from parapneumonic pleurisy and malignant pleurisy.

Adult↗
PubMed1995

Pyrethroids, nerve poisons: how their risks to human health should be assessed.

The extensive worldwide efforts of structural modification of natural pyrethrins for better performances have resulted in successful development of a wide variety of synthetic pyrethroids with tremendously high efficacy, knock-down activity or vapor action, and/or with acceptable environmental stability and safety. Currently these pyrethroids including their preferentially manufactured stereoisomers are widely used in agriculture, and for public health as well as household insect control. The detailed toxicology and metabolism studies intended to attain human risk assessment have revealed that with voltage-dependent sodium channel as target site pyrethroids induce pronounced repetitive activity characterized grossly by tremor, hypersensitivity, choleoathetosis, and salivation. In addition, so-called cyano-pyrethroids cause transient skin paresthesia in workers. With regard to tumorigenicity, mutagenicity, teratogenicity and developmental toxicity, no significant findings have been reported. Pyrethroids are eliminated from the animals quite rapidly and completely, undergoing oxidation and ester hydrolysis followed by various conjugations, with low tissue residues. Thus, overall, sound scientific bases exist for human risk assessment under the present usage conditions.

Animals↗
PubMed1995

[A rapid susceptibility test of Mycobacterium tuberculosis using hybridization protection assay].

The conventional drug susceptibility tests of Mycobacterium tuberculosis are time-consuming and usually require 2 to 4 weeks to obtain final results. In this study, we attempted to develop a novel method for rapid detection of drug-resistant M. tuberculosis using hybridization protection assay (HPA). Clinically isolated strains of M. tuberculosis including seven isoniazid (INH) susceptible strains and six resistant strains were used. The organisms grown on Ogawa egg medium were inoculated into Middlebrook 7H9 broth and cultured at 37 degrees C for one week. Then, the inoculum of each strain was prepared as a tenfold dilution of bacterial suspension at McFarland No. 0.5. The inocula were mixed with INH solutions to yield final concentrations of 0.1 and 1.0 micrograms/ml, and the resulting bacterial suspensions with or without test drug were cultured on the swaying plate at 37 degrees C for up to 5 days. At intervals, 50 microliters of each sample was withdrawn and subjected to the protocol of the HPA using acridinium-ester (AE) labeled DNA probe, and then the relative light unit (RLU) was read in a luminometer. In the case of the susceptible strains, a significant difference in the mode of increase in RLU ratio (% of RLU on day x/RLU on day 0) was observed between the INH-treated and drug-free control sets within three days of cultivation, while no such differences were seen in the case of the resistant strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Acridines↗
PubMed1994

[Clinical investigation of obstructive pneumonia with lung cancer].

Nineteen episodes (18 patients) of obstructive pneumonia occurring in 247 patients with lung cancer were clinically examined, and the following findings were obtained. 1) All 18 patients were male smokers, with an average of 64 years. 2) Body temperatures stood above 37 degrees C in 95% of the 19 episodes. Leukocytosis was detected in 41%, and neutrophilia was observed in 69%. CRP values were positive in all episodes. 3) The frequency of obstructive pneumonia according to the site of lung cancer was 13.2% in proximal tumors and 1.7% in peripheral tumors. Pathologically, the frequency was 5.2% in adenocarcinomas 7.6% in squamous cell carcinomas, 15.6% in small cell carcinomas and 9.1% in large cell carcinomas. Squamous cell carcinomas even in Stage I led to obstructive pneumonia at the rate of 13.0%. In contrast, higher frequency was observed in adenocarcinomas in Stage II or later and small cell carcinomas in Stage IIIB or later. 4) Obstructive pneumonia was detected at the time of discovery of lung cancer in 48% of the 18 patients, and during treatment and in the terminal stage in 26% respectively. 5) Chest X-ray examinations showed that 42% of the pneumonia cases were lobar pneumonia and 11% had pleural effusion. 6) In expectorated sputum, 50% of bacteria isolated were gram-negative, 10% were gram-positive and 40% were unknown. 7) Most of the bacteria isolated from expectorated sputum showed a good susceptibility to antimicrobial agents, but those proved clinically ineffective. 8) The prognosis of obstructive pneumonia was significantly affected by performance status and levels of total protein and choline-esterase.

Aged↗
PubMed1994

[Evaluation for rapid detection of rifampicin-resistant mycobacterium tuberculosis by polymerase chain reaction-single strand conformation polymorphism].

We evaluated usefulness of the rapid diagnostic method for detection of rifampicin (RFP)-resistant Mycobacterium tuberculosis, which was based on polymerase chain reaction. The MICs of RFP were measured for 38 clinical isolates of Mycobacterium tuberculosis which were suspected to be RFP-resistant organisms, and 12 strains were found to be resistant to RFP. The PCR primers used were the same as those reported by Telenti et al, which were targeting the RNA polymerase beta subunit gene (rpoB). We confirmed that this gene was possessed by all the strains tested. Eight strains out of the 12 strains with RFP-resistant phenotype were demonstrated to have a point mutation or some alterationin the rpoB gene on the basis of PCR-single strand conformation polymorphism (SSCP). Thus, the sensitivity of our method was calculated as 67%. In addition, we could not detect any alterations in the rpoB gene by all RFP-susceptible strains. These results indicated that rapid detection of the RFP-resistant Mycobacterium tuberculosis was possible directly from clinical specimens by using PCR-SSCP technique.

Base Sequence↗
PubMed1993

Effects of procymidone on reproductive organs and serum gonadotropins in male rats.

To investigate the mechanism and toxicological significance of testicular interstitial cell tumors (ICT) observed in a long-term rat study with procymidone, N-(3,5-dichlorophenyl)-1,2-dimethylcyclopropane-1,2-dicarboximi de, male Sprague-Dawley rats were fed procymidone in diets for up to 6 months with a positive control group receiving a single subcutaneous injection of cadmium chloride. Examinations mainly for gonadal functions such as serum testosterone and luteinizing hormone (LH), reproductive organ weight and histopathology presented evidence of the indirect involvement of gonadotropins in the production of ICT in rats. A significant increase in both serum testosterone and LH was observed in the early stage at high dietary concentrations of procymidone without any lesion in gonadal systems in histopathology, whereas administration of cadmium chloride produced the expected substantial increase in serum LH and a concomitant decrease in serum testosterone with a marked damaging effect on gonadal systems. Increases in serum testosterone and LH levels in animals receiving procymidone were reversible. The no-effect level for procymidone on serum testosterone and LH was 300 ppm over six months of treatment. The possible mechanism of ICT production in rats by non-genotoxic procymidone, structurally similar to flutamide, a synthetic non-steroidal antiandrogen, is likely to be derived from its induction of a hypergonadotropism due to the competitive binding to the androgen receptor, preventing the normal effect of testosterone to control the circulating level of LH.

Animals↗
PubMed1993

Studies on the therapeutic effect of 2-pyridine aldoxime methiodide (2-PAM) in mammals following organophosphorus compound (OP)-poisoning (report II): aging of OP-inhibited mammalian cholinesterase.

We studied the ability of 2-PAM to reactivate cholinesterase (ChE) inhibited by organophosphorus compounds (OPs) and aging. We estimated the reactivation rate with 2-PAM following inhibition of ChE by fenitrothion, methylparathion or ethylparathion using erythrocytes of rat and rabbit and rat brain. The period of time during which inhibited ChE could be reactivated was shorter in the case of inhibition by fenitrothion or methylparathion than in the case of inhibition by ethylparathion. This results suggest that aging is related to the presence of the alkyl group in OPs, and occurs faster in the case of inhibition by OPs with an O,O-dimethyl moiety than in the case of inhibition by OPs with an O,O-diethyl moiety.

Animals↗
PubMed1993

Studies on the therapeutic effect of 2-pyridine aldoxime methiodide (2-PAM) in mammals following organophosphorus compound-poisoning (report III): distribution and antidotal effect of 2-PAM in rats.

The metabolic fate of 2-PAM and its antidotal effect on organophosphorus compound poisoning in rats were studied. When 14C-2-PAM was administered intravenously, the amount of 14C reaching the brain was small. Following administration by intramedullary injection, 14C was present in high concentrations in the brain, and 72-90% of the 14C present in the brain corresponded to the unchanged form of 2-PAM. 2-PAM was rapidly excreted into the urine and feces following either intramedullary or intravenous administration. The half-life of 2-PAM in the brain following intramedullary administration was 1.52 hr. Intramedullary administration of 2-PAM to rats poisoned with fenitrothion or malathion enabled their survival and induced reactivation of brain cholinesterase.

Animals↗
PubMed1993

The affinity of procymidone to androgen receptor in rats and mice.

To clarify the mechanism of gonadotropin imbalances and the differential response of rat and mouse testicular interstitial cells (Leydig cells) to procymidone, N-(3,5-dichlorophenyl)-1,2-dimethylcyclopropane-1,2-dicarboximi de, male Sprague-Dawley rats and ICR mice were fed procymidone in diet for 2 weeks at 0, 700, 2,000 and 6,000 ppm for rats, or 0, 1,000, 5,000 and 10,000 ppm for mice. Testosterone and luteinizing hormone (LH) levels in serum, testis or pituitary and the in vitro binding affinities of procymidone, flutamide and related compounds to the androgen receptor in prostate cytosol of rats and mice were examined. Hypergonadotropism in rats and mice was clearly observed in the same order two weeks after the initiation of treatment with procymidone. Increased levels of testosterone and LH in serum at 6,000 ppm and LH in pituitary at and above 700 ppm in rats were observed. In mice, testosterone levels in serum and testis elevated at 10,000 ppm. LH levels in serum and pituitary elevated significantly as well at around 5,000 to 10,000 ppm. In the competitive binding assay, procymidone showed a significant but lower binding affinity comparing to that of cyproterone acetate, the steroidal androgen receptor antagonist, for the androgen receptor in both rats and mice under the condition that unlabeled dihydrotestosterone (DHT) effectively inhibited the binding of [3H]-DHT to the androgen receptor in both species. The relative binding affinity (RBA) of procymidone was of the same order as that of flutamide, a synthetic non-steroidal antiandrogen structurally similar to procymidone. These results indicate that procymidone is an active antiandrogen and the androgen receptor antagonism is the likely mechanism of action.

Animals↗
PubMed1992

Effect of a novel class I antiarrhythmic agent, TYB-3823, on the calcium current in single guinea pig ventricular myocytes.

The effect of TYB-3823 on Ca2+ current (ICa) of guinea pig ventricular myocytes was investigated by means of whole-cell patch-clamp technique. TYB-3823 (100-1,000 microM) caused a concentration-dependent decrease in ICa. Furthermore, a reduction of ICa induced by TYB-3823 (1,000 microM) was progressively accentuated by repetitive membrane depolarization, indicating a rate-dependent block of ICa. However, the inhibitory potency on ICa was approximately 1/1000 of a Ca2+ antagonistic agent, verapamil hydrochloride. Considering evidence that 3-30 microM TYB-3823 decreased the maximum upstroke velocity of the action potential of guinea pig ventricular muscles, it is indicated that the drug does not show its Ca2+ antagonistic property in the usual concentration range as a class I antiarrhythmic agent.

Animals↗
PubMed1992

[A clinical study of tuberculous pleurisy].

Forty-eight cases of tuberculous pleurisy were examined and the following results were obtained. (1) Most of the patients were male, and there was no significant age and underlying diseases. (2) Fever and chest pain were observed mainly in younger patients, and sputum and dyspnea in older patients. (3) All of the cases examined had exudative pleural effusion, and increased ADA activity was frequently observed. (4) Mycobacterium tuberculosis was detected in the sputum of 65%, and also in the pleural effusion of 28% of the patients. The pathological diagnosis of tuberculosis was made by pleural biopsy in 83% of the patients, suggesting that pleural biopsy is very useful in the diagnosis of tuberculosis pleurisy. (5) The prognosis of the patients with tuberculosis pleurisy was good. Steroid therapy was generally ineffective.

Adolescent↗