Biomedical subjects

W Sakamoto

Publications and source records attributed to W Sakamoto.

At least 37 records · Page 2Linked to original sources

PubMed1998

Role of the transition zone for elevating serum prostate-specific antigen in benign prostatic hyperplasia.

BACKGROUND: Patients with benign prostatic hyperplasia (BPH) have a wide range of concentrations of PSA. However, it is not known what factors influence the concentration of serum PSA other than the prostate volume. BPH is composed of an enlarged transition zone (TZ) and other zones (nonTZ). The TZ is thought to play a more important role than the nonTZ in determining the concentration of serum PSA in BPH patients. METHODS: We investigated the individual glandular zone volume, the amount of PSA produced by each zone and the PSA density in each zone in 23 patients with histologically-confirmed BPH. The PSA density in the TZ was calculated by dividing the difference between the serum PSA before and after surgical resection by the specimen weight. We examined the influence of these parameters on the concentration of serum PSA in BPH patients. RESULTS: The serum PSA concentration correlated with the amount of PSA produced by the TZ (r=0.90, P< 0.0 1), but not the nonTZ (r=0.25, P=0.29). The concentration of serum PSA also showed a significant correlation with the TZ volume (r=0.67, P< 0.01) and the PSA density in the TZ (r=0.51, P< 0.05), but not with the PSA density in the nonTZ (r=-0.06, P=0.81). Also, age was inversely correlated with the PSA density in the TZ (r=-0.69, P< 0.01). CONCLUSION: The hypertrophic prostate cell volume (TZ volume) and activity (PSA density in the TZ) significantly correlated with the concentration of serum PSA in BPH patients, and the TZ cell activity decreased inversely with age in these BPH patients.

Age Factors↗

PubMed1997

Cloning and molecular analysis of the Arabidopsis gene Terminal Flower 1.

The Arabidopsis gene Terminal Flower 1 (TFL1) controls inflorescence meristem identity. A terminal flower (tfl1) mutant, which develops a terminal flower at the apex of the inflorescence, was induced by transformation with T-DNA. Using a plant DNA fragment flanking the integrated T-DNA as a probe, a clone was selected from a wild-type genomic library. Comparative sequence analysis of this clone with an EST clone (129D7T7) suggested the existence of a gene encoding a protein similar to that encoded by the cen gene which controls inflorescence meristem identity in Antirrhinum. Nucleotide sequences of the region homologous to this putative TFL1 gene were compared between five chemically induced tfl1 mutants and their parental wild-type ecotypes. Every mutant was found to have a nucleotide substitution which could be responsible for the tfl1 phenotype. This result confirmed that the cloned gene is TFL1 itself. In our tfl1 mutant, no nucleotide substitution was found in the transcribed region of the gene, and the T-DNA-insertion site was located at 458 bp downstream of the putative polyadenylation signal, suggesting that an element important for expression of the TFL1 gene exists in this area.

Amino Acid Sequence↗

PubMed1997

Functional complementation of an oxa1- yeast mutation identifies an Arabidopsis thaliana cDNA involved in the assembly of respiratory complexes.

The nuclear gene OXA1 is essential for respiratory growth in yeast. It codes for a chaperon-like protein, and has pleiotropic effects on the assembly of cytochrome c oxidase and ATP synthase of the mitochondrial respiratory chain. To study respiratory complex formation in plants, we have cloned a homolog of the yeast oxa1- in Arabidopsis thaliana, OXA1At, by functional complementation of a yeast oxa1- mutant. OXA1At is a single copy gene and appears to be constitutively expressed in A. thaliana. Although OXA1At encodes a protein sharing only 30% amino acid identity with the yeast Oxa1 protein, hydrophobic domains likely corresponding to trans-membrane domains are strictly conserved. Cytochrome spectra and measurements of respiratory activities show that replacement of the yeast Oxa1 protein with the A. thaliana homolog leads to correct assembly and activity of cytochrome c oxidase, but to partial restoration of ATPase activity. Our results suggest that the Oxa1At protein is essential for the respiratory complex assembly in A. thaliana, and that genes involved in mitochondrial multiprotein complex formation can be conserved between plants and other organisms.

Amino Acid Sequence↗

PubMed1997

An unusual mitochondrial atp9-rpl16 cotranscript found in the maternal distorted leaf mutant of Arabidopsis thaliana: implication of GUG as an initiation codon in plant mitochondria.

Properties of an unusual atp9-rpl16 cotranscript preferentially found in the maternal distorted leaf mutant of Arabidopsis thaliana, which had arisen from a genetic cross between chloroplast mutator and wild-type plants, were examined. Analysis of RNA editing of this cotranscript showed that one editing event in the rpl16 coding region created a UGA stop codon. This raises a possibility that a downstream GUG codon can serve as an initiation codon for rpl16.

Amino Acid Sequence↗

PubMed1997

Putative phospholipid hydroperoxide glutathione peroxidase gene from Arabidopsis thaliana induced by oxidative stress.

An Arabidopsis cDNA encoding putative phospholipid hydroperoxide glutathione peroxidase (PHGPX) was cloned and sequenced. The cDNA comprised 803 bp and included an open reading frame which encodes a polypeptide of 169 amino acid residues. The deduced amino acid sequence showed about 80 and 50% homology with plant putative PHGPXs and mammalian PHGPXs, respectively. Southern blot analysis suggested that putative PHGPX gene was a single-copy gene. The expression profile of the putative PHGPX in Arabidopsis under NaCl and Al/Fe treatments, which generate oxidative stress, was analyzed. Northern blot analysis revealed that the Arabidopsis putative PHGPX mRNA levels were increased about 3 and 4.5 times after exposure to NaCl and Al/Fe, respectively. These results suggest that the putative PHGPX gene is induced by oxidative stress in Arabidopsis.

Aluminum↗

PubMed1996

Effect of vitamin E on expression of cyclooxygenase-2 in lipopolysaccharide-stimulated rat macrophages.

To clarify the role of vitamin E (alpha-tocopherol) for the induction of cyclooxygenase-2 (COX-2) in rat macrophages stimulated by lipopolysaccharide (LPS), vitamin E-enriched macrophages were prepared by intraperitoneal injection of vitamin E for 6 days at a rate of 5 mg per day. The production of PGE2 was increased in dose- and time-dependent manners by addition of LPS in both control and vitamin E-enriched peritoneal macrophages. The maximum effect of LPS was observed in 12 h at concentration of 5 micrograms/ml. By analyzing COX-2 mRNA level by Northern blot and COX-2 enzyme mass and phosphotyrosine by Western blot, it was revealed that the increase of PGE2 production reflected the induction of COX-2 expression through activation of tyrosine kinase. Vitamin E failed to inhibit PGE2 production in LPS-stimulated macrophages; however, genistein, a tyrosine kinase inhibitor, completely inhibited the production at 100 microM. These results suggest that vitamin E does not inhibit COX-2 expression via LPS-mediated tyrosine kinase signal transduction pathway.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1996

Identification of macrophage migration inhibitory factor (MIF) in human skin and its immmunohistochemical localization.

The presence and tissue localization of macrophage migration inhibitory factor (MIF) in human skin were examined. Reverse transcription-polymerase chain reaction analysis revealed that MIF mRNA was expressed in both surgically obtained normal human epidermis and primary cultured human keratinocytes. The expression of MIF was further confirmed by Western blot analysis, which demonstrated a single band at about 12.5 kDa using a polyclonal antibody against human recombinant MIF. Immunohistochemical studies showed that MIF existed in human epidermis, especially in the basal layer. The pathophysiological role of MIF in human skin remains undefined; however, the present results indicate that MIF may play an important role in immunity, inflammation and cellular differentiation of epidermal cells.

Animals↗

PubMed1996

Isolation and characterization of cDNA clones corresponding to the genes expressed preferentially in floral organs of Arabidopsis thaliana.

Seventeen cDNA clones of genes corresponding to mRNAs expressed preferentially in floral organs of Arabidopsis thaliana were obtained by differential screening of a flower bud cDNA library, and classified into five groups (1A, 17A, 1B, 4B and 5B) by cross-hybridization and restriction analysis. Sequence analysis revealed that the 1A-1 and 17A-1 clones encode vegetative storage proteins (VSPs). The VSP mRNAs were detected in a small amount in leaves and increased to a limited level by wounding. Both 1B-1 and 5B-1 clones were homologous to transmembrane protein cDNAs. The protein encoded by 4B-1 clone contained a proline-rich region, but no homologous proteins were found in databases.

Amino Acid Sequence↗

PubMed1996

Degradation of T-kininogen by cathepsin D and matrix metalloproteinases.

Cathepsin D, matrix metalloproteinase (MMP)-2, MMP-3 (stromelysin), and MMP-9 were isolated from rat granulomatous tissues. HT1080 human fibrosarcoma cells and rheumatoid synovial cell CM. At acidic conditions, cathepsin D cleaved T-kininogen into small peptides and released Met-T-kinin-Leu (kinin precursor), but failed to release kinin. MMP-3 cleaved T-kininogen into a 57 kDa fragment as measured by SDS-PAGE and Western blot analysis using anti-T-kininogen antiserum. On the other hand, no degradation of T-kininogen occurred during incubation with MMP-2 or MMP-9100/1) at pH 7.5 for 7 h.

Cathepsin D↗

PubMed1996

Altered mitochondrial gene expression in a maternal distorted leaf mutant of Arabidopsis induced by chloroplast mutator.

Chloroplast mutator (chm) of Arabidopsis is a recessive nuclear mutation that causes green and white variegation in leaves and is inherited in a non-Mendelian fashion. In this study, we have identified and characterized a mutant observed in F1 and backcrossed BC1 populations from a cross between chm1-3 and ecotype Columbia. This mutant, maternal distorted leaf (MDL), grows very poorly and is distinguished by distorted rough leaves and aborted flowering organs. Electron microscopic observation showed that in MDL plants, a significant portion of mitochondria are abnormal and appear to be nonfunctional. DNA gel blot and sequence analysis of the MDL mitochondrial DNA (mtDNA) revealed rearrangements in two mtDNA fragments associated with rps3-rpl16 genes (encoding ribosomal proteins S3 and L16, respectively). One rearrangement resulted in the insertion of the rps3-rpl16 operon downstream of atp9. An independent deletion in this region had eliminated the majority of rps3. In contrast, another rearrangement deleted part of rpl16, whereas rps3 remained intact. RNA gel blot analysis indicated that expression of these genes is also altered as a consequence of the mtDNA rearrangements. Thus, a mutation at the CHM locus affects mitochondrial gene expression, and impaired mitochondrial function may result in the distorted phenotype.

Amino Acid Sequence↗

PubMed1995

The C-terminal region, Arg201-Gln209, of glutathione S-transferase P contributes to stability of the active-site conformation.

The C-terminal region of rat glutathione S-transferase P (GST-P) was deleted by either carboxypeptidase (CPase) A and B or site-specific truncation to evaluate the role of the region in the catalytic mechanism. The C-terminal sequence from the 201st to 209th amino-acid residues is Arg-Pro-Ile-Asn-Gly-Asn-Gly-Lys-Gln. When seven of the C-terminal amino-acid residues from the C-terminus were removed by the CPases, the catalytic activity decreased in parallel with the amino-acid removal, amounting to less than 5% of that of the wild-type GST-P. On the other hand, a decrease of the catalytic activity was observed in a different manner when the C-terminal sequence was site-specifically truncated. The VmaxGSH/KmGSH values of the mutants withthree (GSTd207-209), four (GSTd206-209) and seven (GSTd203-209) C-terminal amino-acid residues deleted, were comparable or similar to that of the wild-type GST-P, whereas those of five (GSTd205-209), six (GSTd204-209), and eight (GSTd202-209) amino-acid residue-truncated mutants decreased to 43%, 40%, and 19% of that of the wild-type GST-P, respectively. Similar results were obtained as for VmaxCDNB/KmCDNB. The nine amino-acid residue-truncated mutant showed no catalytic activity. Heat treatment at 50 degrees C for 5 min had little effect on the catalytic activities of the wild-type GST-P and GSTd204-209, whereas those of GSTd207-209, GSTd206-209, GSTd203-209 and GSTd202-209 decreased to 22%, 27%, 18% and 10%, respectively, compared to the catalytic activity of the non-treated enzymes. Considering these results, it is concluded that the C-terminal region, Arg201-Gln209, has an important role in stabilizing the active-site conformation.

Amino Acid Sequence↗

PubMed1995

[Primary hyperparathyroidism--choice of surgical procedures and follow up after surgery].

Surgery for primary hyperparathyroidism (PHPT) is usually one of the most gratifying of all operations; however, at times, it can be one of the most frustrating. Parathyroidectomy has been practiced for about 70 years. During that time, a great deal of knowledge about the anatomy, embryology, pathology, and physiology of this disease has been acquired. Difficulties in parathyroidectomy for PHPT are due to the variability in the number of parathyroid glands, the different locations of normal and pathologic glands from others that are subtly diseased. To be successful, a parathyroid surgeon must have an excellent knowledge of the anatomy, embryology, and pathophysiology of the parathyroid glands. The results of parathyroid surgery for PHPT in the 1990s are excellent when done by experienced surgeons. These findings strongly advocate special training and interest in parathyroid surgery in order to ensure success.

Follow-Up Studies↗

PubMed1994

A role for oxygen radicals in rat monocytic leukemia cell differentiation under stimulation with platelet-activating factor.

Combined stimulation, by superoxide ions generated by the xanthine-xanthine oxidase reaction, and platelet-activating factor (PAF), induced cell differentiation of rat monocytic leukemia cells (c-WRT-LR) to macrophage-like mature cells. Monitoring of cytochrome c reduction revealed that PAF stimulation induced the release of superoxide ions from c-WRT-LR. To further investigate the effect of superoxide ions in the autocrine or paracrine mechanism in cell differentiation, molecular species of the oxygen radicals under PAF stimulation were examined using the EPR spin trap, 5,5'-dimethyl-1-pyrroline N-oxide (DMPO). PAF and/or phorbol myristate acetate caused the formation of EPR spectra, a combination of DMPO/.OOH and DMPO/.OH. Since both spectra were diminished in the presence of superoxide dismutase, it was concluded that DMPO/.OH was derived from superoxide ions. Mannitol and catalase suppressed cell differentiation induced by combined stimulation with PAF and oxygen radicals generated by the xanthine-xanthine oxidase reaction. Taken together, these results suggest that hydroxyl radicals generated by Fenton reaction from H2O2 may be involved in the mechanism of cell differentiation in rat monocytic leukemia cells.

Animals↗

PubMed1994

Function of the Chlamydomonas reinhardtii petd 5' untranslated region in regulating the accumulation of subunit IV of the cytochrome b6/f complex.

Translational control is an important regulatory mechanism in chloroplasts, and is thought to be mediated by cis-acting elements in the 5' untranslated regions (UTRs) of mRNAs. Chloroplast transformation was used to replace the wild-type Chlamydomonas reinhardtii petD 5' UTR with mutated versions. Transformants containing altered 5' UTRs had either a wild-type photosynthetic phenotype, a leaky non-photosynthetic phenotype, or were unable to grow photosynthetically. Among those transformants with a wild-type phenotype were ones containing mutations in a putative Shine-Dalgarno sequence element. The results indicate that two regions of the 362 nucleotide (nt) 5' UTR may act as positive elements for translation, one located between nt 150 and 200, and the other situated approximately 40 nt upstream of the start codon, at nt 320. In every case where translation was compromised, petD mRNA accumulated to a lower level than in wild-type cells, ranging from 15% to 60% in different strains. It was concluded that specific regions of the petD 5' UTR mediate translational activation, and that mRNA stability may be linked to translatability.

Animals↗

PubMed1994

The petD gene is transcribed by functionally redundant promoters in Chlamydomonas reinhardtii chloroplasts.

FUD6, a nonphotosynthetic mutant of Chlamydomonas reinhardtii, was previously found to be deficient in the synthesis of subunit IV of the cytochrome b6/f complex, the chloroplast petD gene product (C. Lemaire, J. Girard-Bascou, F.-A. Wollman, and P. Bennoun, Biochim. Biophys. Acta 851:229-238, 1986). The lesion in FUD6 is a 236-bp deletion between two 11-bp direct repeats in the chloroplast genome. It extends from 82 to 72 bp upstream of the 5' end of wild-type petD mRNA to 156 to 166 bp downstream of the 5' end. Thus, the deletion extends into the putative promoter and 5' untranslated region of petD. No petD mRNA of the normal size can be detected in FUD6 cells, but a low level of a dicistronic message accumulates, which contains the coding regions for subunit IV and cytochrome f, the product of the upstream petA gene. petD transcriptional activity in FUD6 is not significantly altered from the wild-type level. This transcriptional activity was eliminated by petA promoter disruptions, suggesting that it originates at the petA promoter. We conclude that the petD-coding portion of most cotranscripts is rapidly degraded in FUD6, possibly following processing events that generate the 3' end of petA mRNA. A chloroplast transformant was constructed in which only the sequence from -81 to -2 relative to the major 5' end of the petD transcript was deleted. Although this deletion eliminates all detectable petD promoter activity, the transformant grows phototrophically and accumulates high levels of monocistronic petD mRNA. We conclude that the petD gene can be transcribed by functionally redundant promoters. In the absence of a functional petD promoter, a lack of transcription termination allows the downstream petD gene to be cotranscribed with the petA coding region and thereby expressed efficiently.

Animals↗

PubMed1994

petD mRNA maturation in Chlamydomonas reinhardtii chloroplasts: role of 5' endonucleolytic processing.

Complex processing of primary transcripts occurs during the expression of higher-plant chloroplast genes. In Chlamydomonas reinhardtii, most chloroplast genes appear to possess their own promoters, rather than being transcribed as part of multicistronic operons. By generating specific deletion mutants, we show that petD, which encodes subunit IV of the cytochrome b6/f complex, has an RNA processing site that is required for accumulation of monocistronic petD mRNA in petD promoter deletion mutants; in such mutants, transcription of petD originates from the upstream petA promoter. The 5' ends of transcripts initiated at the petD promoter are probably also generated by processing, since the 5' end of monocistronic petD mRNA is the same in wild-type strains as it is in the petD promoter mutants. The location and function of the processing site were further examined by inserting petD-uidA fusion genes into the chloroplast genome (uidA is an Escherichia coli gene that encodes beta-glucuronidase). When a promoterless petD-uidA fusion gene was inserted downstream of petA, a monocistronic uidA transcript accumulated, which was apparently initiated at the petA promoter and was processed at a site corresponding precisely to the petD mRNA 5' end. When a construct including only sequences downstream of +25 relative to the mature mRNA 5' end was inserted into the same site, a dicistronic petA-uidA transcript accumulated but no monocistronic uidA transcript could be detected, suggesting that a processing site lies at least partially within the region from -1 to +25. Beta-glucuronidase activity was not detected in transformants that accumulated only the dicistronic petA-uidA transcript, suggesting that the first 25 bp of the 5' untranslated region are required for translation initiation. One explanation for this translational defect is that Chlamydomonas chloroplasts cannot translate the second coding region of some dicistronic messages.

Animals↗

PubMed1994

Urinary levels of gamma-carboxyglutamic acid and its clinical significance.

Urinary gamma-carboxyglutamic acid (gamma-Gla) levels were determined in healthy subjects of all ages. The urinary gamma-Gla levels were highest in infants (0-1 years), then fell in an age-dependent manner, again in subjects reaching a minimum value in adults, then gradually increased over 60 years of age. Urinary gamma-Gla levels therefore change markedly with aging. The relationships between the urinary gamma-Gla excretion and plasma levels of prothrombin and protein C in patients with various hepatic diseases or diabetes mellitus were examined and compared with those in healthy adults. Both plasma prothrombin and protein C levels were decreased in all patients with liver disease compared with healthy adults. In patients with hepatitis and liver cirrhosis, the decrease did not, however, affect the gamma-Gla excretion. In addition, in patients with hepatoma or carcinoma with liver metastases, the urinary gamma-Gla levels were increased. In patients with diabetes mellitus, the urinary gamma-Gla levels and plasma levels of prothrombin and protein C tended to increase, but this was not significant. The present results indicate that simultaneous measurement of the levels of urinary gamma-Gla and plasma prothrombin and protein C is a useful tool for the diagnosis of liver diseases and diabetes mellitus.

1-Carboxyglutamic Acid↗

PubMed1994

[Clinical study of primary hyperparathyroidism--diagnosis, parathyroidectomy and late result of operation].

We retrospectively studied clinical problems for 55 patients with primary hyperparathyroidism who were operated on at our hospital. The chance to discovery of primary hyperparathyroidism and its accompanied symptoms were various. Other than classical symptoms, hypertension was noted in 12 patients and malignant tumors in 9. Forty-four percent of patients who had no bone related symptoms were found to have decreased bone mineral density (BMD). Even the patients with normal BMD were seen to increase the BMD, postoperatively. We thought that the parathyroidectomy was indicated for the asymptomatic patients with normal BMD. Biochemical investigation showed that positive rate were 50% for PTH-C, 94% for PTH-HS, 78% for intact PTH, 87% for serum total calcium and 98% for serum ionized calcium. Serum ionized calcium and intact PTH were useful for the diagnosis of patients who had normocalcemia or slight elevation of serum calcium. The sensitivity was 61% for ultrasound sonography (US) and 49% for computer tomography (CT) and scintigram, respectively. The detection rate of US and CT was positively related to the size of the parathyroid glands, but scintigram was not. The rate with which the parathyroid glands can be recognized during operation increased from 30% in the former group to 52% in the later group. As a result, 11% of the patients with adenoma had too much surgery and 29% of the patients with hyperplasia had too little surgery.

Adult↗