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Biomedical subjects

T Okuno

Publications and source records attributed to T Okuno.

At least 19 recordsLinked to original sources
PubMed1995

Structural analysis of PKS1, a polyketide synthase gene involved in melanin biosynthesis in Colletotrichum lagenarium.

Albino mutants (Pks-) of Colletotrichum lagenarium form nonmelanized appressoria and possess little penetrating ability on the host plant. The defect in albino mutant 79215 (Pks-) is considered to lie in pentaketide biosynthesis and/or pentaketide cyclization during melanin biosynthesis. The cosmid pAC7, carrying the PKS1 gene, when transformed into the albino mutant restores the wild-type melanin phenotype. We have determine the DNA sequence and the transcriptional organization of the PKS1 gene. The PKS1 gene contains one open reading frame, consisting of 3 exons separated by two short introns. The predicted PKS1 polypeptide consists of 2187 amino acids and shows significant similarities with other polyketide synthases, particularly that encoded by wA in Aspergillus nidulans, involved in conidial pigmentation. The PKS1 gene contains highly conserved beta-ketoacyl synthase, acetyl/malonyl transferase, and acyl carrier protein domains. We propose that the C. lagenarium PKS1 gene encodes a polyketide synthase involved in melanin biosynthesis.

Amino Acid Sequence↗
PubMed1995

Hepatic hepatitis C virus RNA as a predictor of a long-term response to interferon-alpha therapy.

OBJECTIVE: To identify predictors of a long-term response to interferon-alpha therapy in chronic hepatitis C and to determine whether hepatitis C virus (HCV) was eradicated in patients with chronic hepatitis C who had a long-term response to therapy. DESIGN: A retrospective analysis. SETTING: In- and outpatient liver clinic of a municipal hospital in Japan. PATIENTS: 47 patients with chronic hepatitis C who responded to interferon-alpha were divided into two groups: 22 patients with a long-term response (serum aminotransferase levels remained normal for > 1 year after therapy) and 25 patients with a short-term response (serum aminotransferase levels increased again after therapy). MEASUREMENTS: Genotyping of HCV, titers of HCV RNA in liver and serum samples (using the reverse transcriptase-polymerase chain reaction), histologic activity index, and liver histologic tests during and 1 year after therapy. RESULTS: Among the 22 long-term responders, HCV RNA was no longer detectable in liver and serum samples of 21 (95%) at the end of therapy and remained undetectable in the serum of 20 (91%) and in the liver of 19 (86%) 1 year after therapy. Liver histologic tests improved substantially immediately after therapy and 1 year after therapy in the long-term responders; however, 18 (82%) of these patients still had mild, chronic hepatitis. Among the 25 short-term responders, HCV RNA was still detected in the liver of 19 (76%) and in the serum of 9 (36%) at the end of therapy. Multivariate logistic regression analysis showed that the persistent presence of hepatic HCV RNA at the end of therapy was the strongest predictor of relapse. CONCLUSION: These findings suggest that HCV infection was eradicated in most of the long-term responders to interferon-alpha therapy because HCV RNA could no longer be detected in their serum and liver samples and because a significant improvement gradually occurred in their liver histologic results. The persistent presence of hepatic HCV RNA at the end of therapy was the most important predictor of relapse.

Adult↗
PubMed1995

Chemical form of selenium-containing metabolite in small intestine and liver of mice following orally administered selenocystine.

The chemical form of a selenium-containing metabolite in the small intestine following a single oral administration of selenocystine was investigated with ICR male mice. Selenium content in the small intestine of animals treated with 50 mg/kg selenocystine significantly increased 15 min, 1 h and 6 h after treatment. In contrast, selenocystine significantly depressed the intestinal reduced glutathione (GSH) level at 1 h after administration. A significant negative correlation between the selenium level and the level of GSH in the small intestine was observed (r = -0.83, p < 0.001). Analysis of the intestinal metabolite of selenocystine showed that selenium-containing metabolites elute in two fractions from a Sephadex G-25 column: the low-molecular fraction (peak I) contained the selenocystine, while the high-molecular fraction (peak II) contained selenocysteine-containing metabolite. An in vitro experiment was performed to gain insight into the mechanism for selenocysteine-containing metabolite production in the intestinal cytosol. When selenocystine or selenocysteine reacted with excess GSH in the presence of intestinal homogenate, the peak II fraction which involved the selenocysteine-containing metabolite was recognized in the Sephadex G-25 chromatogram. From an examination of the distribution of the selenocysteine-containing metabolite, it was recognized that this metabolite exists in plasma and liver cytosol of mice after oral administration of selenocystine. These results suggested that the mice treated with selenocystine produce selenocysteine-containing metabolite by reaction of selenocystine with excess GSH in the small intestine, and the metabolite is then transported to the liver through blood plasma.

Administration, Oral↗
PubMed1995

Inhibition of brome mosaic virus (BMV) amplification in protoplasts from transgenic tobacco plants expressing replicable BMV RNAs.

Transgenic tobacco plants (V123 plants) expressing a set of full-length brome mosaic virus (BMV) genomic RNAs from the cauliflower mosaic virus 35S promoter were produced. The accumulation level of BMV RNAs in V123 plant cells was approximately 1% of that in nontransgenic tobacco protoplasts inoculated with BMV RNAs. The level of BMV RNA in V123 protoplasts did not increase after inoculating the protoplasts with BMV RNAs, whereas V123 protoplasts supported the accumulation of cucumber mosaic virus (CMV) RNAs to a level similar to that in non-transgenic tobacco protoplasts after inoculation with CMV RNA. Such BMV-specific resistance was also observed in protoplasts from V12 plants expressing full-length BMV RNA1 and RNA2, both of which are required and sufficient for BMV RNA replication. On the other hand, protoplasts from M12 plants, expressing truncated BMV RNA1 and RNA2 in which the 3' 200 nucleotides required for BMV RNA replication were deleted, exhibited weaker resistance to infection with BMV RNA than V12 protoplasts, although the accumulation level of truncated BMV RNA1 and RNA2 in M12 protoplasts was higher than that of BMV RNA1 and RNA2 in V12 protoplasts. These results suggest that expression of BMV RNA replicons is involved in the induction of resistance, rather than high-level accumulation of BMV RNAs and/or their encoded proteins.

Bromovirus↗
PubMed1995

Magnetic resonance imaging for the diagnosis of prostate cancer metastatic to bone.

OBJECTIVE: To examine the role of magnetic resonance imaging (MRI) in the evaluation of osseous metastasis in patients with prostate cancer. PATIENTS AND METHODS: A series of 36 patients with known prostate cancer, who were undergoing MRI and an isotope bone scan, were studied. RESULTS: Of 19 positive bone scans, MRI was read as negative for metastasis in one. Of eight equivocal scans, two MR images were interpreted as positive and six as negative. Of nine negative scans MRI was positive in one. Further MRI demonstrated additional metastatic lesions that were not shown by bone scintigraphy in six patients. MRI clearly indicated the areas of spinal cord compression in five patients with spinal metastases and associated myelopathy. CONCLUSION: MRI is helpful in the diagnosis of metastatic prostate cancer, especially when other radiographic examinations are inconclusive or spinal cord compression is suspected.

Bone Neoplasms↗
PubMed1995

Human herpesviruses 6 and 7 in cervixes of pregnant women.

We looked for human herpesvirus 6 (HHV-6) and HHV-7 genomes in the cervixes of pregnant women in the late stages of their pregnancies. Of 72 samples collected with cervical swabs and amplified by nested PCR, we found that 14 (19.4%) and 2 (2.7%) contained detectable HHV-6 and HHV-7 genomes, respectively. The two samples in which HHV-7 DNA was detected also contained HHV-6 genomes. Hybridization of HHV-6 DNA amplified by PCR with variant-specific probes revealed that all of these DNA samples belonged to variant type B. These results indicated that HHV-6 and/or HHV-7 exists in the cervixes of infected women in late pregnancy and may cause perinatal infection.

Base Sequence↗
PubMed1995

[Magnetic resonance imaging for the evaluation of prostate cancer metastatic to bone].

The response of bone metastatic lesions to endocrine therapy was assessed by repeated magnetic resonance imaging (MRI) and an isotope bone scan after an average period of 7.0 months (2-10 months) in 12 patients with prostate cancer. MRI used both T1-weighted spin echo technique and short TI IR (STIR) sequence. Of 7 patients with hormone-dependent cancer, the bone metastatic lesions resolved or became vague in all patients on STIR image, while in only 4 and 3 on T1-weighted image and bone scan, respectively. Of 5 patients with hormone-refractory cancer, the lesions progressed on both MRI and bone scan in all patients except one who had initially had diffusely metastatic lesions of systemic bone. The results indicate that STIR image of MRI is helpful for the therapeutic evaluation of bone lesions.

Adenocarcinoma↗
PubMed1995

The virological and histological states of anti-hepatitis C virus-positive subjects with normal liver biochemical values.

We investigated anti-hepatitis C virus (HCV) titers, HCV RNA levels in liver and serum, genetic variability in the hypervariable region of the genome, the form of the virus in the circulation, and liver histology in 21 anti-HCV-positive subjects with sustained normal liver biochemical values. Titer of anti-HCV was determined by second generation anti-HCV-passive hemagglutination assay, and HCV RNA levels were semiquantitated by reverse transcriptase polymerase chain reaction (PCR). In 19 (90%) of the 21 subjects who had a higher titer of anti-HCV (> or = 2(14)), HCV RNA was detected in both serum and liver, and histological examination showed minimal or mild chronic hepatitis in all. In the remaining 2 patients who had a lower titer of anti-HCV, HCV RNA was not detected in serum and liver, and liver histology was normal. Anti-HCV titers and HCV RNA levels in serum and liver in the 19 HCV RNA-positive subjects were compared with those levels in the 41 patients with biopsy-proven chronic hepatitis C and elevated serum aminotransferase levels as a control group. There were no significant differences in viral levels in serum and liver between the two groups. To further investigate virological differences between the two groups with regard to degree of genetic variability and the form in the circulation, we performed the PCR-single strand conformation polymorphism (PCR-SSCP) of the hypervariable region 1 and the immunoprecipitation analyses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Tubulointerstitial nephropathy--radionuclide imaging diagnosis].

There are many spectrums in renal diseases which induce tubulointerstitial nephropathy (TIN). Primarily, the renal tubule and interstitium are involved but glomerular and vascular lesions are found in the chronic course of TIN. Renal scintigraphy is poor for evaluating characteristic aspects of tubular function of TIN but demonstrate individual renal function as a whole. Particularly, measurement of the 99m-Tc-DMSA renal uptake rate is useful for evaluating a functioning tubular mass.

Humans↗
PubMed1995

[A case of spinal dural arteriovenous fistula associated with normal pressure hydrocephalus].

A 62-year-old male presented with urinary incontinence, gait disturbance and dementia for 6 months. Neurological examination revealed severe paraparesis (1/5), sensory disturbance below Th10, neurogenic bladder and absence of patellar and achilles tendon reflexes. CT scan showed mild brain atrophy and symmetric ventriculomegaly with periventricular lucency. Magnetic resonance imaging (MRI) showed a linear flow void lesion on the dorsal surface on the back of his swollen lower spinal cord. Myelography showed a filling defect and flow disturbance of contrast medium in lower thoracic levels, suggesting the presence of adhesive arachnoiditis. Spinal angiography demonstrated a fistula formation between dural branches of bilateral L4 lumbar arteries and ventral spinal and radicular veins on the surface of the dura mater of L4/5 levels. Considering his past history of repeated lumbar puncture for tuberculous meningitis at the age of 22 years, a diagnosis of acquired spinal dural arteriovenous fistula probably due to repeated lumbar puncture was made. Fistulas were embolized with N-butyl cyanoacrylate. And normal pressure hydrocephalus was treated by ventriculoperitoneal shunt. Follow-up CT scans showed a decrease of the size of the ventricular system. Etiology of acquired spinal arteriovenous fistula has been reported. In the case, repeated lumbar puncture may be a possible cause of arteriovenous fistula in the lower spinal dura mater. However, the reason why it took so long to form a fistula after the lumbar puncture remains to be elucidated. We suggest that an increased protein concentration due to disturbance of cerebrospinal fluid flow might be a cause of normal pressure hydrocephalus (NPH).

Arteriovenous Fistula↗
PubMed1995

[A case of absence of the left internal carotid artery].

A case of absence of the left internal carotid artery with epilepsy was reported. Only a few cases of absence of the internal carotid artery with epilepsy in childhood have been reported in Japan. A flow void image of the cavernous sinus portion of the left internal carotid artery was not obtained on MRI. MR angiography and digital subtraction angiography also did not reveal the left internal carotid artery. On thin slice, axial CT scanning of the skull base, the right carotid canal was normally observed, but the left carotid canal was hypoplastic. It was suggested that the epileptic focus was in the right hemisphere, judging from the fast waves dominant over the right hemisphere on ictal EEG, and the hyperfusion in the right parietal and occipital lobes seen on 99mTc-HMPAO SPECT one hour after the seizure.

Angiography, Digital Subtraction↗
PubMed1994

Molecular epidemiological studies of human herpesvirus 6 in families.

The mode of transmission of human herpesvirus 6 (HHV-6) was investigated by molecular epidemiological techniques in four families. HHV-6 was isolated from the peripheral blood of seven infants with exanthem subitum, including siblings, and from the saliva of two mothers. These isolates were examined for genetic relatedness by means of restriction enzymes analysis of purified DNA. While the profiles of the digestion patterns differed among families, they were very similar in a particular family. These results may suggest that HHV-6 is transmitted primarily from mother to child.

Adult↗
PubMed1994

Functional roles of terminal glycomoieties in varicella-zoster virus infection.

Terminal glycomoieties of varicella-zoster virus glycoproteins were characterized by their reactivity with lectins and glycosidases, and the functional roles of terminal sugars were analyzed by cell-free virus infectivity. Terminal glycan structures of gpl possessed sialic acid linked alpha (2-3) to galactose of O-linked glycan and galactose-beta (1-4)-N-acetylglucosamine of N-linked glycan. Those of the putative gpIV possessed galactose-beta (1-4)-N-acetylglucosamine of N-linked glycan. Both glycoproteins had mannose alpha (1-3, 6, or 2) linked to mannose in their glycans. Their biological functions on cell-free virus infectivity were assessed by using lectins and exoglycosidases. Sialic acid of glycans on both the viral envelope and the cell surface had a negative effect on infectivity, and the latter had a larger effect on infectivity than the former. Maackia amurensis agglutinin, which recognizes sialic acid, enhanced infectivity more than expected from the simple neutralization of the negative effects of sialic acids between cells and virus. alpha-Mannosidase and alpha-glucosidase treatments of virus significantly reduced infectivity but those of cells did not. Therefore, alpha-mannose and alpha-glucose residues on the viral envelope had functional roles in cell-free virus infection. Inactivation of virus infectivity by concanavalin A was mainly due to the blocking of functional roles of terminal alpha-mannose and alpha-glucose residues of viral glycoproteins.

Acetylglucosamine↗
PubMed1994

Restoration of pathogenicity of a penetration-deficient mutant of Collectotrichum lagenarium by DNA complementation.

Infection by Colletotrichum lagenarium requires formation of an appressorium and of a penetration peg. A mutant, 83,348, defective in morphogenesis of the penetration peg was unable to penetrate into cellulose membranes or infect cucumber leaves. DNA transformation using a wild-type genomic library constructed in pKVB resulted in two transformants, Ppr1 and Ppr2, with restored penetration peg formation, from 2,000 benomyl-resistant transformants. However, penetration into cellulose membranes by these transformants ranged from 30 to 40% compared to greater than 90% by wild-type. Southern-blot hybridization showed that a single copy of a cosmid clone had integrated into the genome of the transformants. A 12.0-kbp fragment of the cosmid vector with the flanking region of wild-type genomic DNA was recovered by plasmid rescue from Ppr1. Using the flanking DNA sequences as a probe for colony blot hybridization, a genomic clone was identified and designated pRP46. Transformants obtained following transformation with pRP46 were able to penetrate cellulose membranes. The penetration frequency of pRP46 transformants ranged from 25 to 65%. Transformants were also pathogenic on cucumber.

Cloning, Molecular↗