Biomedical subjects

M Yoshimoto

Publications and source records attributed to M Yoshimoto.

At least 127 records · Page 7Linked to original sources

PubMed1998

A novel member of the Ig superfamily, RPE7, expressed on the retinal pigment epithelial cell and Müller cell of the bovine retina.

The retinal pigment epithelium of the vertebrate eye plays a major part in the maintenance of ocular function. To identify molecules involved in the exertion of their physiological functions, monoclonal antibodies against bovine retinal pigment epithelial cells were made. Analysis by immunofluoresence and immunoelectron microscopy showed that one of the monoclonal antibodies named anti-RPE7 stained the cell surface of retinal pigment epithelial cells and Müller cells. The anti-RPE7 antibody was revealed to recognize molecules of 45-55 kDa by Western blot analysis. Molecular cloning of the RPE7 cDNA and sequence analysis of the amino acids revealed that protein RPE7 belonged to the Ig superfamily. The high homology of RPE7 with metalloproteinase inducer suggests that the protein RPE7 might play a role in the matrix (interphotoreceptor matrix and basement membranes) remodeling as well as in retinal pigment epithelial cell migration under pathological conditions.

Amino Acid Sequence↗

PubMed1998

Accumulation of alpha-synuclein/NACP is a cytopathological feature common to Lewy body disease and multiple system atrophy.

Recently, we have shown that the precursor of the non-Abeta component of Alzheimer's disease amyloid (NACP), also known as alpha-synuclein, is a major component of Lewy bodies (LBs) as well as neuronal and glial cytoplasmic inclusions in multiple system atrophy (MSA). To elucidate whether the accumulation of NACP is specific to LB disease and MSA, we further studied 83 autopsied cases with various neurological disorders, using anti-NACP antibodies. In LB disease, NACP immunoreactivity was present in all of the LBs and Lewy neurites in both the central and peripheral nervous systems, the pale bodies in the substantia nigra, and dystrophic neurites in the hippocampal CA2/3 region. Immunoelectron microscopy revealed that the reaction product was localized within filamentous structures and associated granular structures. In MSA, NACP immunoreactivity was found in the intracytoplasmic inclusions of both neuronal and oligodendroglial cells, neuronal intranuclear inclusions, and swollen neuronal processes. No NACP immunoreactivity was found in a variety of other neuronal or glial inclusions in other disorders, including Alzheimer's disease, Pick's disease, progressive supranuclear palsy, corticobasal degeneration, motor neuron disease and triplet-repeat diseases. These findings strongly suggest that the accumulation of NACP is a cytopathological feature common to LB disease and MSA.

Cellular Senescence↗

PubMed1998

High proportion of missense mutations of the BRCA1 and BRCA2 genes in Japanese breast cancer families.

Mutations in either of two recently identified genes, BRCA1 and BRCA2, are thought to be responsible for approximately two-thirds of all cases of autosomal-dominantly inherited breast cancer. To examine the nature and frequency of BRCA1 and BRCA2 mutations in Japanese families exhibiting a high incidence of breast cancer, we screened 78 unrelated families in this category for mutations of these two genes. Examining the entire coding sequences as well as exon-intron boundaries of both genes by polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) and multiplex-SSCP analysis, we identified possible disease-causing alterations in BRCA1 among affected members of 15 families and in BRCA2 in another 14 families. In 15 of those 29 families, the affected individuals carried missense mutations, although most germline mutations reported worldwide have been deletions or nonsense mutations. Our results, indicating that missense mutations of BRCA1 and BRCA2 tend to predominate over frameshifts or nonsense mutations in Japanese breast cancer families, will contribute significantly to an understanding of mammary tumorigenesis in Japan, and will be of vital importance for future genetic testing.

BRCA2 Protein↗

PubMed1998

Fabrication of a new substrate for atomic force microscopic observation of DNA molecules from an ultrasmooth sapphire plate.

A new stable substrate applicable to the observation of DNA molecules by atomic force microscopy (AFM) was fabricated from a ultrasmooth sapphire (alpha-Al2O3 single crystal) plate. The atomically ultrasmooth sapphire as obtained by high-temperature annealing has hydrophobic surfaces and could not be used for the AFM observation of DNA. However, sapphire treated with Na3PO4 aqueous solution exhibited a hydrophilic character while maintaining a smooth surface structure. The surface of the wet-treated sapphire was found by x-ray photoelectron spectroscopy and AFM to be approximately 0.3 nm. The hydrophilic surface character of the ultrasmooth sapphire plate made it easy for DNA molecules to adhere to the plate. Circular molecules of the plasmid DNA could be imaged by AFM on the hydrophilic ultrasmooth sapphire plate.

Aluminum Oxide↗

PubMed1998

Single and repeated electroconvulsive shocks activate dopaminergic and 5-hydroxytryptaminergic neurotransmission in the frontal cortex of rats.

1. The effect of electroconvulsive shock (ECS) on the extracellular concentration of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) was examined in the frontal cortex of rats with the use of in vivo microdialysis. 2. The extracellular concentration of DOPAC, HVA and 5-HIAA was largely increased after the first ECS treatment. The increase after the eighth ECS treatment tended to be attenuated or was significantly attenuated as compared to that after the first ECS treatment. The baseline concentration of DOPAC and 5-HIAA was significantly increased after repeated ECS, though that of DA and HVA did not show any significant change after repeated ECS. 3. These results suggest that the activating effect of repeated ECT on 5-hydroxytryptaminergic (5-HT) and DA neurotransmission, (especially on 5-HT neurotransmission), is significant in improving depression both in patients with Parkinson's disease (PD) and in those who do not suffer from PD.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1998

Identification of a new commonly deleted region within a 2-cM interval of chromosome 11p11 in breast cancers.

Allelic loss has been observed on the short arm of chromosome 11 in a variety of human cancers. We have examined 184 breast cancers for allelic loss anywhere in chromosome 11p, using 15 well-spaced microsatellite markers. Allelic loss was observed in 86 cases (47%) and a new commonly deleted region 2-cM in length was identified at 11p11 between loci D11S986 and D11S1313, in addition to a 12-cM region of a common deletion at 11p15.5. A significant association was found between allelic loss on 11p15.5 and LOH on 11p11 and the loss of progesterone receptors.

Autoradiography↗

PubMed1998

Expression pattern of synucleins (non-Abeta component of Alzheimer's disease amyloid precursor protein/alpha-synuclein) during murine brain development.

The non-Abeta component of Alzheimer's disease amyloid precursor protein (NACP) is predominantly a neuron-specific presynaptic protein that may play a central role in neurodegeneration because NACP fragments are found in Alzheimer's disease amyloid and a mutation in the NACP gene is associated with familial Parkinson's disease. In addition, NACP may play an important role during synaptogenesis and CNS development. To understand better the patterns of NACP expression during development, we analyzed the levels of this protein as well as the levels of another synaptic protein (synaptophysin) by ribonuclease protection assay, western blotting, and immunocytochemistry in fetal, juvenile, and adult mouse brain. From embryonic day 12 to 15, there was a slight increase, which was then followed by a more dramatic increase at later time points. Immunocytochemical staining for NACP increases throughout these stages as well. Although NACP appeared early in CNS development, synaptophysin levels started to rise at a later stage. These findings support the contention that NACP might be important for CNS development. Furthermore, the cytosolic component of NACP precedes the particulate component in development, indicating that a redistribution of the protein to the membrane fraction may be important for events later in neuronal development and in synaptogenesis.

Alzheimer Disease↗

PubMed1998

Multiplex mutation screening of the BRCA1 gene in 1000 Japanese breast cancers.

To detect BRCA1 mutations in Japanese breast cancer patients, we screened 1,000 unselected primary cancers for mutations in exon 11, which accounts for 61% of the entire BRCA1 coding sequence. Using a method based on multiplex single-strand conformational polymorphism (SSCP) analysis of multiple restriction fragments generated by restriction-enzyme digestion of amplified DNA, we identified eight mutations. All eight were germline mutations; four of them were non-sense mutations or small deletions resulting in premature stop codons, and the other four were missense mutations. The Japanese carriers of these mutant BRCA1 alleles had developed breast cancers at ages ranging from 45 to 62, five of them bilaterally.

Aged↗

PubMed1998

Mapping of a new target region of allelic loss to a 2-cM interval at 22q13.1 in primary breast cancer.

Allelic losses on chromosome arm 22q are frequently observed in human meningiomas and in carcinomas of the colon, ovary, and breast. Among 140 primary breast cancers we examined for loss of heterozygosity (LOH) at 16 polymorphic loci on the long arm of chromosome 22, 56 (40%) showed LOH for at least one locus. Eleven of these tumors had retained heterozygosity for markers proximal to the NF2 locus but showed LOH for markers distal to NF2. Deletion mapping indicated a new common region of deletion, 2-cM in extent, at q13.1 between Interleukin 2 receptor beta (IL2RB) and D22S279. Our results raise the possibility that one or more tumor suppressor genes associated with breast cancer may exist at 22q13.1. Comparison of these results with clinicohistological data indicated that allelic losses on 22q tend to occur more frequently in tumors of malignant histological types.

Alleles↗

PubMed1998

[Relationship between DNA ploidy and survival in breast cancer].

The DNA ploidy pattern from fresh frozen specimens and survival rate was investigated in 91 primary breast cancers. Diploid patterns were found in 32 (35.2%) and aneuploid patterns in 59 (64.8%). The 5-year overall survival rate was significantly lower in aneuploid cases (76.3%) than diploid cases (93.8%) (p = 0.042), while there was no significant difference in disease-free survival between the two groups. there were negative nodes, no significant differences in 5-year overall or disease-free survival between patients with diploidy and aneuploidy. In contrast, when there were positive nodes, the 5-year overall and disease-free survival rates in patients with aneuploidy were 60.6% and 48.5%, which were significantly lower (p = 0.048 and p = 0.030) than the corresponding percentages of 92.3% and 84.6%, in those with diploidy. When the ploidy pattern was compared with other factors, a very close correlation was found between the ploidy pattern and histological grading (p < 0.0001). The ploidy pattern determined by flow cytometric DNA analysis may reflect the grade of malignancy of the breast cancer.

Breast Neoplasms↗

PubMed1998

Changes in morphology of neuroblastoma cells treated with all-trans retinoic acid combined with transfer of the C-terminal region of the amyloid precursor protein.

Alzheimer disease is a progressive neurodegenerative disorder that is characterized by a loss of cognitive and memory functions. Amyloid fibrils deposited in neuritic plaque is mainly beta-amyloid protein (Abeta) that is derived from amyloid precursor protein (APP). The secreted form of APP, which is corresponded to N-terminal portion of APP, shows neurotrophic activities. On the other hand, Abeta and cytoplasmic domains of APP are thought to be neurotoxic. In order to investigate the effect of C-terminal fragment of APP covering Abeta and the cytoplasmic domain upon cell growth and differentiation, we established a stably transfected cell line producing the C-terminal 100 amino acid peptide of APR The transfected clones stained positively with anti-Abeta monoclonal antibody, TB-1. The growth rate of the transfected cells was not significantly different from that of mock-transfected cells or native NB39 cells. After treatment with all-trans retinoic acid (ATRA), mock-transfected cells extended neurite processes and showed neuronal-like differentiation, while a transfected clone overexpressing C-terminal fragment did not present neuronal-like morphology. These results suggest that ATRA-induced neurite extension may be suppressed by overexpression of the C-terminal fragment of APP.

Amyloid beta-Peptides↗

PubMed1997

Correlation of Allelic Losses and Clinicopathological Factors in Primary Breast Cancers.

Human breast cancers frequently show allelic loss or loss of heterozygosity (LOH) at apecific chromosomal regions. To understand the possible role of these genetic alterations in tumor development and progression, we examined LOH at loci on chromosomal arms 1p, 3p. 11p, 13q, 16q, 18q, and 22q in 140 to 246 cases of primary breast cancers and compared it with lymph node metastasis, histological type, tumor stage, estrogen receptor (ER) and progesterone receptor (PgR) status. LOH at 1p22-31 correlated with lymph node metastasis and a tumor size of greater than 2 cm. LOH at 13q12-14 and 18q21 were most frequently observed in tumors of the solid-tubular type. LOH at 1p34-36 was more frequent in tumors of the scirrhous and solid-tubular types than in other less aggressive histological types. Furthermore, a significant association was observed between LOH at 3p14-21, 11p11-15 and 13q12-14 and the absence of progesterone receptors. These results suggest that some clinical characteristics of breast cancers are determined by loss of tumor supperssor genes present at specific chromosomal regions.

Journal Article↗

PubMed1997

NACP, a presynaptic protein, immunoreactivity in Lewy bodies in Parkinson's disease.

NACP, originally identified as a precursor of the non-Abeta component of Alzheimer's disease amyloid (NAC), is now known to be identical to alpha-synuclein, a presynaptic protein in the human brain. Recently, a mutation in the alpha-synuclein gene in families with autosomal dominant Parkinson's disease (PD) was identified. We carried out immunohistochemical examinations of the brains of sporadic PD patients using anti-NACP and anti-ubiquitin antibodies. Consistent with previous studies, the anti-NACP antibody immunostained the neuropil in a punctate pattern throughout the brain. Moreover, much stronger NACP immunoreactivity was found in Lewy bodies and degenerating neurites in the brainstem. Serial sections immunolabeled with anti-ubiquitin or anti-NACP showed that all ubiquitin-immunoreactive LBs were also NACP-immunoreactive. These findings suggest that alteration of NACP metabolism is involved in the pathogenesis of PD, particularly in Lewy body formation, leading to neurodegeneration.

Aged↗

PubMed1997

NACP, a synaptic protein involved in Alzheimer's disease, is differentially regulated during megakaryocyte differentiation.

Non-amyloid-beta component precursor (NACP) is a presynaptic protein which may play a role in amyloidogenesis in Alzheimer's disease (AD). Since an abnormal function of platelets has been demonstrated in AD, platelets could be used as a model to investigate the role of NACP in this disease. We characterized the patterns of NACP and beta-synuclein expression in a megakaryocyte-platelet system (K562). In this hematopoietic cell line, NACP expression was up-regulated during phorbol ester-induced megakaryocytic differentiation, while beta-synuclein was down-regulated. Consistent with this, NACP but not beta-synuclein was abundantly expressed in platelets. Immunogold electron microscopy of platelets showed that NACP is loosely associated with the plasma membrane, the endomembrane system and, occasionally, with the membrane of secretory alpha-granules. These findings suggest that coordinate expression of the synuclein family members may play a critical role during hematopoietic cell differentiation. Additionally, expression of the synuclein family members may be developmentally regulated during neural differentiation.

Amyloid↗

PubMed1997

Terminal morphology of two branches arising from a single stem-axon of pretectal (PSm) neurons in the common carp.

The induction of postsynaptic structures by presynaptic terminals is suggested in a teleost brain. Neurons in the nucleus pretectalis superficialis pars magnocellularis (PSm) in the common carp are known to send fibers to the corpus mamillare (CM) and the nucleus lateralis valvulae (NLV). Individual axons of PSm neurons bifurcate (or give off an axon collateral), both of which reach the target areas in the CM and NLV. The morphology of horseradish peroxidase-labeled terminals in the CM and NLV appears quite different in light microscopy. Terminals in the CM appear as a fine network of beaded (2-4 microns in diameter) fibers, while those in the NLV are larger (8-12 microns in transverse diameter) and cup-shaped, partially enveloping the soma of individual NLV neurons. In electron microscopy, however, these synapses in the CM and NLV share several ultrastructural similarities. Small (0.2 to 0.4-micron thick, 0.4 to 0.7-micron long) spine-like protrusions arising from dendrites in the CM, and from cell bodies in the NLV, invaginate into the axon terminals, and the synaptic junctions are always formed at the base of the protrusion in both areas. Development of this unusual morphology is inferred to be directed from the presynaptic side. The morphological similarity of the spine-like protrusions to the "spinule," which is thought to be formed in response to synaptic activation, is discussed.

Animals↗

PubMed1997

Interaction between botulinum neurotoxin type A and ganglioside: ganglioside inactivates the neurotoxin and quenches its tryptophan fluorescence.

This study found that ganglioside quenched the tryptophan fluorescence of botulinum neurotoxin type A (BoNT A), accompanied by the inactivation of the toxin under low ionic strength conditions. This finding suggests that the ganglioside-binding site of BoNT A contains tryptophan residues. The quantum yield (a conformation parameter) in BoNT A under high ionic strength conditions differed from that under low ionic strength. This observation indicates that high ionic strength may alter the conformation of BoNT A, resulting in failure of the interaction between BoNT A and ganglioside.

Botulinum Toxins, Type A↗

PubMed1997

Dopamine releasing response in rat striatum to single and repeated electroconvulsive shock treatment.

1. The effect of electroconvulsive shock (ECS) on extracellular concentration of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) was examined with the use of in vivo microdialysis in rat striatum. 2. Extracellular concentration of DA was markedly increased up to 183% after single ECS, and that of DOPAC, HVA and 5-HIAA was also significantly increased. The increase after the eighth ECS was attenuated compared to their increase soon after the first ECS. After repeated ECS, baseline concentration of DOPAC, HVA and 5-HIAA was significantly increased, and baseline DA concentration tended to increase. 3. These results suggested that single and repeated ECS activated metabolism of DA and 5-hydroxytryptamine in rat striatum. Activated metabolism of DA may be responsible for the clinical effect of electroconvulsive therapy for parkinsonism.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Magnetic resonance galactography for a patient with nipple discharge.

A new method of galactography using magnetic resonance imaging for a patient with nipple discharge is developed. The method is as follows; coronal T1-weight images are obtained after an injection of contrast medium of 1 mmol/L Gd-DTPA directly into the discharge duct, before and after rapid intravenous infusion of Gd-DTPA. A case of a 29-year-old woman with ductal carcinoma in situ with minimal invasion is reported, in which all portions of the entire discharge duct system is clearly shown as viewed from the surface and the surrounding area is enhanced with Gd-DTPA. The enhanced area is coincidental with the extent of the disease. This magnetic resonance galactography for patients with nipple discharge may be used to supplement conventional mammography and/or galactography especially for the evaluation of the extent of disease, although it is somewhat inferior to mammographic galactography in terms of differential diagnosis of ductal disease.

Adult↗