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Biomedical subjects

M Yasuda

Publications and source records attributed to M Yasuda.

At least 235 records · Page 13Linked to original sources
PubMed1997

A case of epithelioid hemangioendothelioma associated with an artery.

We report a case of epithelioid hemangioendothelioma (EHE) arising in the left elbow of a 67-year-old woman. The tumor was characterized by centrifugal growth and association with the brachial artery, causing complete occlusion. Immunohestochemical and electron microscopical features were typical of EHE. The patient was free of local recurrence or disease metastasis for more than 3 years after tumor resection, but subsequently died of respiratory failure due to a primary lung cancer.

Aged↗
PubMed1996

Sequence analysis of the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803. II. Sequence determination of the entire genome and assignment of potential protein-coding regions.

The sequence determination of the entire genome of the Synechocystis sp. strain PCC6803 was completed. The total length of the genome finally confirmed was 3,573,470 bp, including the previously reported sequence of 1,003,450 bp from map position 64% to 92% of the genome. The entire sequence was assembled from the sequences of the physical map-based contigs of cosmid clones and of lambda clones and long PCR products which were used for gap-filling. The accuracy of the sequence was guaranteed by analysis of both strands of DNA through the entire genome. The authenticity of the assembled sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA using the assembled sequence data. To predict the potential protein-coding regions, analysis of open reading frames (ORFs), analysis by the GeneMark program and similarity search to databases were performed. As a result, a total of 3,168 potential protein genes were assigned on the genome, in which 145 (4.6%) were identical to reported genes and 1,257 (39.6%) and 340 (10.8%) showed similarity to reported and hypothetical genes, respectively. The remaining 1,426 (45.0%) had no apparent similarity to any genes in databases. Among the potential protein genes assigned, 128 were related to the genes participating in photosynthetic reactions. The sum of the sequences coding for potential protein genes occupies 87% of the genome length. By adding rRNA and tRNA genes, therefore, the genome has a very compact arrangement of protein- and RNA-coding regions. A notable feature on the gene organization of the genome was that 99 ORFs, which showed similarity to transposase genes and could be classified into 6 groups, were found spread all over the genome, and at least 26 of them appeared to remain intact. The result implies that rearrangement of the genome occurred frequently during and after establishment of this species.

Bacterial Proteins↗
PubMed1996

Mutations in the p53 gene and human papillomavirus infection as significant prognostic factors in squamous cell carcinomas of the oral cavity.

The p53 gene has been indicated to be a tumour suppressor gene that is found in mutated form in common human cancers. Human papillomavirus (HPV) has oncogenic activity in cervical and oral squamous cell carcinomas (SCCs). The E6 protein of HPV is known to bind with p53 protein and inactive the tumor suppressor activity by promoting p53 degradation. Because of this background, we examined 38 primary, resected specimens of oral SCCs for detection of p53 mutations and HPV DNAs. Exons 5 through 8 of the p53 Mutations were observed in nine cases (24%). HPV-DNA detection and typing were performed using PCR with ¿high risk group' HPV-specified primers. HPV DNA sequences were detected in eight cases (21%). The AvaII digestion pattern of PCR-amplified HPV DNA showed that HPV-16 was present in all eight cases. Seven cases were p53 mutation-positive/HPV-negative, six cases were p53 mutation-negative/HPV-positive, and two intraosseus SCC cases were p53 mutation-positive/ HPV-positive. Thus, 15/38 (40%) cases had inactivation of the p53 protein. Interestingly, p53 mutation-negative/ HPV-negative cases had a poorer prognosis than p53 mutation positive or HPV-positive cases (P < 0.01). We conclude that (1) mutation in the p53 gene and/or HPV infection are frequent (40%) in oral SCC; (2) inactivation of p53 function by mutation and HPV infection are important genetic events in the development of 40% integral of oral SCCs; (3) p53 mutation and HPV infection are not mutually exclusive events and (4) other oncogenes or tumor suppressor genes may be crucial in the development of oral SCC if the prognosis is poor.

Aged↗
PubMed1996

What is the earliest malignant lesion in the esophagus?

BACKGROUND: The incidence of early esophageal cancer is definitely increasing due to recent advances in diagnostics. When we discuss early carcinoma of the esophagus, however, there is still controversy as to whether dysplasia is either benign or the earliest malignant lesion. METHODS: Nineteen resected esophaguses with both cancer and dysplasia (including 19 cancers concomitant with 26 dysplastic lesions) were studied for expression of p53 protein. RESULTS: Immunohistochemical overexpression of p53 protein in esophageal dysplasia is almost the same as that in cancer. CONCLUSIONS: Esophageal dysplasia should be recognized as the earliest malignant lesion which already demonstrates cancerous features although it is not immediately critical. A routine endoscopic Lugol's solution test is very useful for both detection and following-up of the early nests in the esophagus. These lesions are good candidates for endoscopic mucosal resection for the purpose of accurate diagnosis or curative treatment.

Esophageal Neoplasms↗
PubMed1996

Histological changes in rat embryonic blood cells as a possible mechanism for ventricular septal defects produced by an N-phenylimide herbicide.

An N-phenylimide herbicide, S-53482, inhibits protoporphyrinogen oxidase, an enzyme common to chlorophyll and heme biosynthesis, and produces embryolethality, teratogenicity [mainly ventricular septal defects (VSD) and wavy ribs], and growth retardation in rats. In order to elucidate the mechanism of the developmental toxicity, in particular VSD, effects of the herbicide on rat embryonic blood cells were investigated histologically at the light and electron microscopic levels at 6, 12, 24, 36, and 48 h after oral administration of the chemical to pregnant rats on day 12 of gestation, the most sensitive day for toxicity. Electron and light microscopy demonstrated mitochondrial lesions, including abnormal iron deposits that were probably due to inhibition of heme biosynthesis, in erythroblasts derived from the yolk sac. Subsequently, degeneration of these erythroblasts occurred followed by erythrophagocytosis. Histologically hearts from exposed embryos had a thin ventricular wall, which may reflect a compensatory reaction to a loss of embryonic blood cells. Thus, the herbicide may induce VSD due to hematological dysfunction caused by the inhibition of heme biosynthesis rather than by direct injurious effects on the heart.

Animals↗
PubMed1996

Species difference in protoporphyrin IX accumulation produced by an N-phenylimide herbicide in embryos between rats and rabbits.

There was a remarkable species difference in developmental toxicity exhibited by S-53482, an N-phenylimide photobleaching herbicide, between rats and rabbits. S-53482 showed embryolethality, teratogenicity, and growth retardation in rats. In contrast, no developmental toxicity was shown in rabbits. The herbicidal activity of S-53482 is due to the photodynamic action of accumulated protoporphyrin IX (PPIX) as a result of inhibition of protoporphyrinogen oxidase (PPO), which is one of the key enzymes in porphyrin biosynthesis common to both plants and animals as part of chlorophyll and heme synthesis. Some plant PPO inhibitors were reported to inhibit mammalian PPO. Therefore, in a search for a possible link between developmental toxicity and enzyme inhibition, PPIX accumulations presumably resulting from PPO inhibition in rat and rabbit embryos were investigated. The results demonstrated that PPIX concentration was increased in rat embryos by 2 orders of magnitude when compared to that of nontreated embryos. On the other hand, no PPIX was accumulated in rabbit embryos even by treatment with a high dose level of S-53482. It was concluded that the species difference in PPIX accumulation corresponded very well to that of the developmental toxicity exhibited by S-53482.

Animals↗
PubMed1996

Lateral lunate morphology: an x-ray study.

The lunate has been described by Kauer as being thinner dorsally than volarly when measured proximal to distal. We used an x-ray method to measure the shape of the lunate in order to compare dorsal and volar thicknesses after recognizing clinically a group of patients with scapholunate dissociation in whom volar flexed lunates were present. Using this method, 292 standard lateral views of the lunate were collected randomly and measured. The shape of the lunate could be classified into 3 types: type D lunates have a thinner dorsal segment and correspond to Kauer's description; type V lunates have a thinner volar segment; type N lunates have equal dorsal and volar segments. There were 196 type D lunates (67%), 67 type V lunates (23%), and 29 type N lunates (10%). The radiolunate angles were measured in a random selection from type D and type V lunates to determine any relationship between the volar segment to dorsal segment thickness (wedge) ratio. No relationship within these groups was identified. However, there was a significant difference in the radiolunate angles between these two groups. Recognition of the prevalence of the type V lunate alters concepts proposed by Kauer and warrants further investigation of factors influencing lunate position.

Carpal Bones↗
PubMed1996

Oesophageal cancer composed of mixed histological types.

Glandular or adenoid cystic differentiation and sarcomatous features are sometimes encountered in oesophageal cancer and such histological variants often coexist with ordinary squamous cell carcinoma. So far no serial evaluation of such mixed histological types of oesophageal cancer has ever been performed, we therefore clinicopathologically investigated such cases While an immunohistochemical study of the p53 protein was also done on four available cases in order to discuss the histogenesis of these tumours. Among the 600 patients with surgically resected oesophageal cancer, seven cases were found to have a mixture of histological variants with ordinary SCC (squamous cell carcinoma) (adenocarcinoma 1, adenoid cystic cancer 3, sarcomatous component 2, basaloid cystic cancer and sarcomatous component 1). All but one case had an elevated type tumour while the predominant components of protrusion were not SCC but variant histological types. Six tumours were restricted to the submucosal layer. An immunohistochemical study of the p53 protein revealed that two of four cases were positive in both the SCC and variant patterns. Mixed histological types of oesophageal cancer composed of SCC and other variants often occur and thus the carcinogenesis of both histological types are considered to be aspects of the same mechanism.

Adenocarcinoma↗
PubMed1996

Involvement of Fyn tyrosine kinase in progression of cytokinesis of B lymphocyte progenitor.

We analyzed the role of Fyn tyrosine kinase in cell cycle progression of B lymphocyte progenitor (pro B cell). Whereas there were no substantial defects in the intramarrow B cell genesis in the fyn(-) mouse, and long-term proliferation of fyn(-) pro B cells was maintained in vitro under a serum containing culture condition, the cell cycle was arrested at G2/M upon serum deprivation. Morphological analyses demonstrated that the cytokinesis of fyn(-) pro B cells was retarded in the presence of serum and that the entry of fyn(-) pro B cells into late telophase was completely blocked under the serum-free condition. In contrast, the earlier phases of mitosis of fyn(-) pro B cells proceeded normally without FCS. This failure to initiate late telophase resulted in the accumulation of elliptical binucleated cells that might be the outcome of the nuclear division without cytokinesis. Consistent with this defect in the progression of cytokinesis, Fyn was localized in the midspace of dividing pro B cells at anaphase. These results suggested that Fyn localizes at the midspace of dividing pro B cells and regulates the progression of cytokinesis.

Animals↗
PubMed1996

Quinolone-resistant Neisseria gonorrhoeae: correlation of alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV with antimicrobial susceptibility profiles.

Fifty-five clinical strains of Neisseria gonorrhoeae were examined for mutations in the gyrA and parC genes and for antimicrobial susceptibility profiles. The MICs of quinolones for 31 strains with alterations in GyrA were significantly higher than the MICs for 24 strains without such alterations. Eleven strains with alterations in both GyrA and ParC were significantly more resistant to fluoroquinolones than those with alterations in GyrA alone. The MICs of cephalosporins for these strains were also significantly higher than those for other strains.

Amino Acid Sequence↗
PubMed1996

Comparison among performances of a ligase chain reaction-based assay and two enzyme immunoassays in detecting Chlamydia trachomatis in urine specimens from men with nongonococcal urethritis.

We evaluated the performances of a ligase chain reaction (LCR)-based assay and two enzyme immunoassays (Chlamydiazyme and IDEIA) in the detection of Chlamydia trachomatis in urine specimens. We compared the results of testing urine specimens by these assays with those of urethral swab culture by examining samples from 131 men with nongonococcal urethritis. Discrepant results were analyzed by testing urethral swab specimens for C. trachomatis by a PCR-based assay. After the resolution of discrepant results, the sensitivity of urethral swab culture was 85.3%, whereas those of the LCR assay, Chlamydiazyme, and IDEIA with urine specimens were 94.1, 82.4, and 94.1%, respectively. The LCR assay and IDEIA were more sensitive than was urethral swab culture. In addition, the LCR assay, with a sensitivity equal to that of IDEIA, was more specific. Overall, the LCR assay proved to be superior to the enzyme immunoassays in detecting C. trachomatis in urine specimens. Testing urine specimens by LCR assay should be a helpful alternative method for diagnosing C. trachomatis urethral infection in men with nongonococcal urethritis.

Chlamydia Infections↗
PubMed1996

Rapid detection of point mutations of the Neisseria gonorrhoeae gyrA gene associated with decreased susceptibilities to quinolones.

Mutations in the gyrA gene resulting in amino acid changes at Ser-91 and Asp-95 are significantly associated with decreased susceptibilities to quinolones in Neisseria gonorrhoeae. To detect these mutations, we developed a rapid and simple assay based on amplification of the region of the gyrA gene containing the mutation sites by PCR and digestion of the PCR product with a restriction enzyme. A naturally occurring HinfI restriction site was present in the region containing the Ser-91 codon, and an artificial HinfI restriction site was created in the region containing the Asp-95 codon by the method of primer-specified restriction site modification. The mutations generating alterations at Ser-91 and Asp-95 were detected as restriction fragment length polymorphisms of the PCR products digested with HinfI. Fifty-five clinical strains of N. gonorrhoeae were examined for mutations in the gyrA gene by this method. Mutations at Ser-91 and/or Asp-95 were detected in all the 31 strains in which the mutations had been confirmed by DNA sequencing. Our method allows simultaneous testing of a large number of strains and provides results within 8 h. This rapid and simple assay could be a useful screening device for genetic alterations associated with decreased susceptibilities to quinolones in N. gonorrhoeae and could facilitate epidemiological studies on clinical isolates of N. gonorrhoeae with decreased susceptibilities to quinolones.

Base Sequence↗
PubMed1996

Enhancement of TdT-mediated dUTP-biotin nick end-labeling (TUNEL) method using mung bean nuclease, a single-stranded DNA digestion enzyme.

The TdT-mediated dUTP-biotin nick end-labeling (TUNEL) method has been employed widely to demonstrate apoptotic cells in routinely prepared paraffin sections. Because the apoptotic cells were reactive with the antibody to single-stranded DNA, we attempted to enhance the TUNEL positivity by pretreatment with single-stranded DNA digestion enzymes, S1 nuclease, and mung bean nuclease. When mung bean nuclease (5 U/50 microliter/section) was incubated at 37 degrees C for 30 min, the TUNEL reaction was most effectively enhanced. Pretreatment with S1 nuclease (0.25 U/50 microliter/section) at 37 degrees C for 45 min was less reliable. Compared with the conventional TUNEL sequence, the enhancement technique using mung bean nuclease enabled us to detect more apoptotic cells in human small intestine, colon, tonsil, thymus, endometrium, ovary, liver, kidney, and pancreas. The positivity was not affected by autolytic change. The mechanism of enhancement is discussed.

Apoptosis↗