Biomedical subjects

M Yoshimoto

Publications and source records attributed to M Yoshimoto.

At least 145 records · Page 8Linked to original sources

PubMed1997

Localization of a breast cancer tumour-suppressor gene to a 3-cM interval within chromosomal region 16q22.

Allelic losses on chromosome 16q in tumour cells are frequent in a variety of malignancies, suggesting the presence of one or more tumour-suppressor genes in the region. Among 210 sporadic breast cancers we examined using 15 microsatellite markers on the long arm of chromosome 16, heterozygosity for at least one locus was lost in 141 (67%). Detailed deletion mapping revealed two distinct commonly deleted regions. One region was defined as a 3-cM interval flanked by markers D16S512 and D16S515 at 16q22; the second consisted of a 9.5-cM interval flanked by markers D16S498 and D16S303 at q24.3. Allelic loss on 16q was observed frequently in small tumours, tumours without lymph node metastasis and tumours of the non-invasive histological type as well as in tumours of more advanced phenotype, suggesting that inactivation of one of at least two tumour-suppressor genes on 16q plays a role in early stage breast carcinogenesis.

Breast Neoplasms↗

PubMed1997

Mapping of a breast cancer tumor suppressor gene locus to a 4-cM interval on chromosome 18q21.

DPC4 and DCC, putative tumor suppressor genes implicated in the genesis of several types of human cancer, lie on the long arm of human chromosome 18. We examined 200 primary breast cancers for allelic losses on chromosome 18, using 15 microsatellite markers distributed along the long arm. Allelic loss was detected most frequently (29-30%) at loci mapped to 18q21. Deletion mapping of the 34 tumors showing partial or interstitial deletions identified a commonly deleted region within the 4-cM interval flanked by D18S474 and D18S487 at 18q21.1-q21.3. Although this interval included the DPC4 and DCC genes, we excluded DPC4 from candidacy when polymerase chain reaction-single-strand conformation polymorphism analysis of each exon failed to detect abnormalities in any of the 54 breast cancers that exhibited loss of heterozygosity involving 18q. Allelic loss on 18q was found more frequently in tumors of the solid tubular histological type (24 of 55, 44%) than in other types (24 of 113, 21%) (P = 0.0049). The results suggest that a tumor suppressor gene located within the 4-cM region at 18q21, either DCC or another gene not yet identified, may play a role in the development of some sporadic breast cancers, particularly those of the solid tubular type.

Alleles↗

PubMed1997

Increased telomerase activities in human pancreatic duct adenocarcinomas.

Telomerase is a key enzyme with regard to immortalization of cancer cells and increased activity has been demonstrated in various human malignant neoplasms. Since little is known of its role in pancreatic cancers, we investigated changes in telomerase activity in human pancreatic duct adenocarcinomas and compared the frequency of increased telomerase activity with the presence of K-ras gene mutations. The samples were obtained from 38 pancreatic duct adenocarcinomas and 7 tumor surrounding tissues at surgical resection. Telomerase activity was examined by telomeric repeat amplification protocol assay and terminal restriction fragment (TRF) length was examined by Southern analysis. K-ras mutation was examined by means of polymerase chain reaction-single strand conformation polymorphism analysis. Among 38 pancreatic carcinomas, 32 (84%) exhibited increased telomerase activities with no apparent relation to the histological type of tumor, tumor size, regional lymphnode involvement and distant metastasis or clinical stage. In tissue surrounding the tumor, telomerase activity was not detected. TRF length tended to be reduced in pancreatic carcinomas. Mutations of K-ras gene were found in 24 out of the 38 (63%) cases. Among the 38 cases, 14 showed increased telomerase activity without K-ras mutation and 4 cases showed K-ras mutation without telomerase activity. These results suggest that increased telomerase activity might be a sensitive genetic diagnostic marker and could be a target for future therapy of pancreatic duct carcinomas.

Biomarkers, Tumor↗

PubMed1997

DAX-1 gene mutations and deletions in Japanese patients with adrenal hypoplasia congenita and hypogonadotropic hypogonadism.

Abnormality of the DAX-1 gene accounts for many instances of congenital adrenal hypoplasia. In the present study, we performed molecular genetic analysis of DAX-1 in 4 unrelated Japanese patients with adrenal hypoplasia congenita and hypogonadotropic hypogonadism. A double-point mutation for V126M and W171X was identified in 1 family and a complex de novo insertion-deletion mutation was identified in a second. The DAX-1 gene was entirely deleted in a 3rd patient as well as in a 4th with the additional feature of glycerol kinase deficiency.

Adolescent↗

PubMed1997

Pubertal changes in testicular 3 beta-hydroxysteroid dehydrogenase activity in a male with classical 3 beta-hydroxysteroid dehydrogenase deficiency showing spontaneous secondary sexual maturation.

Males with classical 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) deficiency manifest appropriate secondary sexual maturation with an elevation in serum testosterone levels at pubertal age. To define the origin of serum testosterone, we evaluated a male patient with classical 3 beta-HSD who showed pubertal development. High values of testosterone and a ratio of delta(5) to delta(4) steroids in the spermatic vein indicated direct production of considerable amounts of testosterone and a persistent defect of 3 beta-HSD activity in the gonad. Immunohistochemical analysis showed distinct immunoreactivity in the Leydig cells of the patient. The patient was homozygous for a nonsense mutation in the type-II 3 beta-HSD gene. We propose that gonadal type-I 3 beta-HSD could be expressed by gonadotropin stimulation at pubertal age, and delta(4)-steroid precursors would convert to testosterone.

3-Hydroxysteroid Dehydrogenases↗

PubMed1996

Two distinct commonly deleted regions on chromosome 13q suggest involvement of BRCA2 and retinoblastoma genes in sporadic breast carcinomas.

BACKGROUND: Frequent allelic losses on the long arm of chromosome 13 in sporadic breast carcinomas suggest that a tumor suppressor gene(s) on 13q is involved in this type of carcinoma. The presence of a familial breast carcinoma susceptibility gene, BRCA2, and the retinoblastoma susceptibility gene (RB) on the same chromosomal arm implies that one or the other, or both, of these genes may be critically affected by those allelic losses. METHODS: To investigate the possible involvement of BRCA2 and RB in sporadic breast carcinomas, the authors examined allelic losses in 246 breast carcinomas with 14 polymorphic microsatellite markers on 13q12.q14. RESULTS: Allelic loss was observed in 95 of the 246 sporadic breast carcinomas (39%). Detailed deletion mapping identified two commonly deleted regions. The more proximal of these two segments was located in a 6-cM interval flanked by marker loci D13S289 and D13S267 and containing the BRCA2 gene; the more distal region was located in a 9-cM interval flanked by marker loci D13S328 and D13S172 and containing the RB gene. Allelic loss on 13q was found more frequently in tumors of the solid tubular histologic type (36 of 66; 55%) than in other types (52 of 146; 36%) (P = 0.0096). Furthermore, a significant association was observed between allelic loss on 13q and the absence of progesterone receptor (P = 0.0001). CONCLUSIONS: The results indicate that BRCA2 and RB are independent targets of allelic loss and that inactivation of either of these genes may play a role in the development of some sporadic breast carcinomas, particularly those of the solid tubular type.

Chromosome Mapping↗

PubMed1996

Characterization of single chain urokinase-type plasminogen activator with a novel amino-acid substitution in the kringle structure.

ECV304 is a cell line established by a spontaneous transformation of endothelial cells of a human umbilical vein. It was shown that ECV304 secretes single chain urokinase-type plasminogen activator (scu-PA). A subclone, ECV304 clone 15, was obtained by acclimatization of parental clone to serum-free medium followed by limiting dilution. The clone was found to produce approximately five times as much scu-PA (approximately 20 IU/10(6) cells per day) as the parental clone after a 40 days' culture. Though the biochemical characteristics of the purified scu-PA were indistinguishable from those of the native scu-PA, it had a lower affinity for fibrin clots under the employed conditions. Molecular cloning of a cDNA encoding the scu-PA has identified a novel substitution from C to T in the nucleotide sequence encoding the kringle structure. The substitution resulted in an alteration from Pro (CCG) to Leu (CTG) at amino-acid position 121, which may be directly or indirectly involved in the decrease in the apparent affinity.

Amino Acid Sequence↗

PubMed1996

Yearly variation of spontaneous somatic mutation frequency in the stamen hairs of Tradescantia clone KU 9 grown outdoors, which showed a significant increase after the Chernobyl accident.

Scoring of spontaneous somatic pink mutation frequency in the stamen hairs of Tradescantia clone KU 9, a heterozygote for flower color (blue/pink; the blue color being dominant), was carried out for 11 years on plants grown outdoors, during the period of May 11-31 (for 3 weeks) in every year from 1982 to 1992. Weekly and yearly variations of the spontaneous mutation frequency were observed, and such variations could mostly be correlated to the difference in temperature. That is, the mutation frequency was generally higher in the weeks and years when the temperature was relatively low, showing the strongest negative correlation with the average minimum temperature. The variations were also correlated to the diurnal temperature difference, the mutation frequency being higher with larger diurnal temperature difference in general. However, the mutation frequency observed in 1986 was exceptionally higher than that expected from the temperature for this year, and was very significantly higher than for other years. The scoring of mutation frequency was thus continued in 1986 for an additional 4 weeks (June 1-28), and it was confirmed that such higher mutation frequencies lasted for 6 weeks in total. The exceptionally high mutation frequency seemed to be related to the radioactive fallout which occurred in early to mid May of 1986, even in Japan, after the serious nuclear reactor accident at Chernobyl, and also to the biological concentrations of radioactive nuclides which subsequently occurred, although it was difficult to conclude this definitely. The mutation frequency in 1987 was second highest, and was also significantly higher than the lowest mutation frequency observed in 1990.

Climate↗

PubMed1996

Mutations in the BRCA1 gene in Japanese breast cancer patients.

Predisposing germline mutations in the BRCA1 gene were identified recently in families with 17 q-linked breast and ovarian cancers. Using single-strand conformation polymorphism (SSCP) analysis, we examined primary breast cancers for mutations in coding exons of BRCA1 in a panel of 103 patients, of whom all either represented early-onset cases (< 35 of age), were members of multiply-affected families, and/or had developed bilateral breast cancers. Mutations were detected in tumors from four patients, all of whom had developed breast cancers bilaterally: a frame-shift due to a 2-bp deletion at codon 797; a nonsense mutation at codon 1214; and two missense mutations, one at codon 271 leading to Val-->Met substitution, and the other at codon 1150 leading to Pro-->Ser substitution. In each case the same mutation was present in constitutional DNA. The mean age of onset was 49 years among the Japanese carriers of BRCA1 mutations identified in this study, in contrast to the mean age of 35 observed among carriers of BRCA1 mutations in a similar U.S. study (Futreal et al., 1994). The evidence reported here supports a rather limited role of BRCA1 in breast carcinogenesis.

Adult↗

PubMed1996

Liver targeting of interferon through pullulan conjugation.

PURPOSE: The purpose of this study was to actively target interferon (IFN) to the liver through its chemical conjugation with pullulan, a water-soluble polysaccharide with a high affinity for the liver. METHODS: Chemical conjugation of IFN with pullulan was achieved by a cyanuric chloride method. Following intravenous injection of the conjugates to mice, their body distribution and the activity of an IFN-induced enzyme, 2', 5'-oligoadenylate (2-5A) synthetase in the liver and other organs, were evaluated. RESULTS: The cyanuric chloride method enabled us to prepare an IFN-pullulan conjugate that retained approximately 7-9% of the biological activity of IFN. Pullulan conjugation enhanced the liver accumulation of IFN and the retention period with the results being reproducible. When injected intravenously to mice, the IFN-pullulan conjugate enhanced the activity of 2-5A synthetase in the liver. The activity could be induced at IFN doses much lower than those of free IFN injection. In addition, the liver 2-5A synthetase induced by conjugate injection was retained for 3 days, whereas it was lost within the first day for the free IFN-injected mice. CONCLUSIONS: IFN-pullulan conjugation was promising for IFN targeting to the liver with efficient exertion of its antiviral activity therein.

2',5'-Oligoadenylate Synthetase↗

PubMed1996

Area dorsalis pars lateralis of the telencephalon in a teleost (Sebastiscus marmoratus) can be divided into dorsal and ventral regions.

Area dorsalis pars lateralis was shown to be subdivided into a dorsal region and a ventral region by a shallow groove on the telencephalic surface. In the dorsal region, three layers were distinguished by Nissl staining; a surface layer I, a middle layer II, and a deep layer III. Although a three-layered structure was also observed in the ventral region, it was not as clear as that in the dorsal region. Cells in area dorsalis pars lateralis were classified by Golgi-Cox staining into 5 types; small cells, horizontal cells, pyriform cells, inverted cells, and multipolar cells. The distribution of zinc was examined by the Neo-Timm method and found to be present in layers I and II and weakly in layer III of the dorsal region but not in layers I and II of the ventral region. The presence of zinc in synaptic terminals in the dorsal region was verified by analytical electron microscopy. Following separate and localized injections of horseradish peroxidase into dorsal and ventral regions, some different fiber connections were revealed. Both dorsal and ventral regions had reciprocal connections with ipsilateral area dorsalis pars centralis, area ventralis pars supracommissuralis, area ventralis pars dorsalis, area ventralis pars posterior, nucleus prethalamicus, and had afferent connections from area ventralis pars lateralis, area ventralis pars intermedia, raphe nuclei, and locus ceruleus. Only the dorsal region, however, received projections from contralateral area dorsalis pars centralis, ipsilateral area dorsalis pars dorsalis, area dorsalis pars medialis, and area dorsalis pars posterior and sent fibers to the inferior lobe, nucleus paracommissuralis, and optic tectum. Although area dorsalis pars lateralis had been thought to be a homogeneous region of the primary visual area of the telencephalon, histochemistry of zinc and fiber connections of the region indicates that the area is subdivided into two regions: dorsal and ventral.

Animals↗

PubMed1996

[Density distribution of dopaminergic neurons in the retina of a marine teleost, Thamnoconus (Navodon) modestus].

By means of tyrosine hydroxylase immnocytochemical detection, regional densities of dopaminergic (DAergic) neurons were measured in 6 whole-mounted retinas of a marine teleost, Thamnoconus (Navodon) modestus. Isodensity lines of DAergic cells in the right retina were drawn to make a contour map. Depending upon the range of cell densities, the retinal field was divided into 3 regions: zone A, containing more than 300 per mm square; zone B, from 200 to 299; and zone C, below 200. Zone A was located in the small temporal (A1) and nasal (A2) areas as well as in the peripheral margin (A3). Zone B formed a horizontal streak-like band between regions A1 and A2. Low density areas (C) were located dorsally or ventrally to zone B. Where the densities were higher, soma sizes appeared to be smaller. DAergic neurons in the peripheral zone A3 were bipolar and the dendrites ran parallel to the retinal margin, while DAergic neurons in the other zones were multipolar and the dendrites ran in various directions. The presence of the small temporal (A1) and nasal areas (A2) with high densities of DAergic neurons, as well as the streak-like area (B) with a relatively high density, may correspond to similar areas in the isodensity contour map of ganglion cells.

Animals↗

PubMed1996

[Assessment of response to chemotherapy by tumor marker in solid neoplasms].

The points at issue in the assessment of response to chemotherapy by tumor marker are discussed, and our guideline is proposed. In cancer clinics, many paradoxical movements of tumor marker are usually recognized in the situations such as heterogeneity changes of neoplasms, acute tumor cytolysis, non-peculiar rise of tumor marker, low level rise of markers near the basal level, which show paradoxical movements apart from clinical response to treatment. Then the guidelines must be settled based under the consideration of these phenomena and tumor marker kinetics. Partial response > = 65% decrease over 4 weeks; No change within < 65% decrease or < 40% increase over 8 weeks; Progressive disease > = 40% increase over 8 weeks. CR must not be defined.

Biomarkers, Tumor↗

PubMed1996

[Recent progress in the diagnosis of nonpalpable breast lesions].

Recent advances in the diagnosis of nonpalpable breast lesions are reviewed. Recently, the technique of stereotaxic fine-needle breast biopsy for nonpalpable, mammographically detected breast lesions is available, and the technique has been proposed as an alternative to surgical biopsy. New equipment of stereo-guided breast biopsy system (LORAD co, system), which is produced for the use of stereotaxic core biopsy, is introduced. We examined 103 nonpalpable, mammographic lesions by this system and 14 carcinomas, including 11 noninfiltrating ones, were discovered. This system has been evident as a cost-effective and reliable method of evaluating mammographic lesions.

Biopsy, Needle↗

PubMed1995

Molecular cloning of mouse epiregulin, a novel epidermal growth factor-related protein, expressed in the early stage of development.

A cDNA clone encoding a novel epidermal growth factor (EGF)-related growth regulator, epiregulin, was isolated from a cDNA library prepared from a mouse fibroblast-derived tumor cell line, NIH3T3/clone T7. The predicted amino acid sequence revealed that the purified epiregulin peptide of 46-amino acids was synthesized as an internal segment of a 162-amino acid putative transmembrane precursor. The structural organization was similar to that of TGF-alpha precursor among the members of the EGF family. Although epiregulin transcript was not detected in several adult normal tissues by Northern blot analysis, approximately 4.8-kb transcript was present in 7-day-old mouse embryo and then diminished to very low or undetectable levels. Our results suggest that epiregulin may play an important role in the regulation of epithelial cell growth during early development.

3T3 Cells↗

PubMed1995

Classic steroid 11 beta-hydroxylase deficiency caused by a C-->G transversion in exon 7 of CYP11B1.

Steroid 11 beta-hydroxylase deficiency (11 beta OHD) is derived from mutations in the P45011 beta gene (CYP11B1) and inherited in an autosomal recessive manner. In the present study, we have performed a molecular genetic analysis of CYP11B1 in a Japanese patient clinically diagnosed as classic 11 beta OHD. Nucleotide sequencing of the PCR-amplified exons from the patient's genomic DNA reveals a unique C-->G transversion that converts codon 384 CGA (arginine) to GGA (glycine) in exon 7. Restriction fragment length polymorphism (RFLP) data demonstrate that the patient is homozygous for this mutation. When the full-length cDNA corresponding to CYP11B1 of the patient is transfected into COS-7 cells, no steroid 11 beta-hydroxylase activity is detectable in mitochondria of the cells. These results indicate that this point mutation completely abolishes P45011 beta activity and causes the classic 11 beta OHD.

Adolescent↗

PubMed1995

Two sisters with clinical diagnosis of Wiskott-Aldrich syndrome: is the condition in the family autosomal recessive?

We report two sisters in a family representing manifestations of Wiskott-Aldrich syndrome (WAS), an X-linked immunodeficiency disorder. An elder sister had suffered from recurrent infections, small thrombocytopenic petechiae, purpura, and eczema for 7 years. The younger sister had the same manifestations as the elder sister's for a 2-year period, and died of intracranial bleeding at age 2 years. All the laboratory data of the two patients were compatible with WAS, although they were females. Sialophorin analysis with the selective radioactive labeling method of this protein revealed that in the elder sister a 115-KD band that should be specific for sialophorin was reduced in quantity, and instead an additional 135-KD fragment was present as a main band. Polymerase chain reaction (PCR) analysis of the sialophorin gene and single-strand conformation polymorphism (SSCP) analysis of the PCR product demonstrated that there were no detectable size-change nor electrophoretic mobility change in the DNA from both patients. The results indicated that their sialophorin gene structure might be normal. Studies on the mother-daughter transmission of X chromosome using a pERT84-MaeIII polymorphic marker mapped at Xp21 and HPRT gene polymorphism at Xq26 suggested that each sister had inherited a different X chromosome from the mother. Two explanations are plausible for the occurrence of the WAS in our patients: the WAS in the patients is attributable to an autosomal gene mutation which may regulate the sialophorin gene expression through the WAS gene, or, alternatively, the condition in this family is an autosomal recessive disorder separated etiologically from the X-linked WAS.

Antigens, CD↗

PubMed1995

NACP, the precursor protein of the non-amyloid beta/A4 protein (A beta) component of Alzheimer disease amyloid, binds A beta and stimulates A beta aggregation.

NACP, a 140-amino acid presynaptic protein, is the precursor of NAC [the non-amyloid beta/A4 protein (A beta) component of Alzheimer disease (AD) amyloid], a peptide isolated from and immunologically localized to brain amyloid of patients afflicted with AD. NACP produced in Escherichia coli bound to A beta peptides, the major component of AD amyloid. NACP bound to A beta 1-38 and A beta 25-35 immobilized on nitrocellulose but did not bind to A beta 1-28 on the filter under the same conditions. NACP binding to A beta 1-38 was abolished by addition of A beta 25-35 but not by A beta 1-28, suggesting that the hydrophobic region of the A beta peptide is critical to this binding. NACP-112, a shorter splice variant of NACP containing the NAC sequence, bound to A beta, but NACP delta, a deletion mutant of NACP lacking the NAC domain, did not bind A beta 1-38. Furthermore, binding between NACP-112 and A beta 1-38 was decreased by addition of peptide Y, a peptide that covers the last 15 residues of NAC. In an aqueous solution, A beta 1-38 aggregation was observed when NACP was also present in an incubation mixture at a ratio of 1:125 (NACP/A beta), whereas A beta 1-38 alone or NACP alone did not aggregate under the same conditions, suggesting that the formation of a complex between A beta and NACP may promote aggregation of A beta. Thus, NACP can bind A beta peptides through the specific sequence and can promote A beta aggregation, raising the possibility that NACP may play a role in the development of AD amyloid.

Alzheimer Disease↗