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Biomedical subjects

Y Mishima

Publications and source records attributed to Y Mishima.

At least 55 records · Page 3Linked to original sources
PubMed1998

Difference in chromatin packaging between active and inactive X chromosomes by fractionation and allele-specific detection.

Using a novel method consisting of chromatin fractionation and allele-specific detection, chromatin packaging is compared between active X (Xa) and inactive X (Xi) chromosomes for five tumor cell clones that were derived from inter-subspecific F1 female mice. Separation of heterochromatic (H) and euchromatic (E) fractions is monitored by hybridization with subtelomeric satellite DNA and ribosomal RNA gene and by PCR amplification of p53 gene/pseudogene with one primer set. The H fraction was enriched with satellite and p53 pseudogene probably existing in heterochromatic regions while the E fraction showed inverse, suggesting fair separation. Analysis with seven marker and three gene loci revealed concentration of alleles on Xi in the H fraction and those on Xa in the E fraction, though the concentration levels varied. This implies that the packaging level of Xi is higher than that of active or inactive euchromatin on Xa. Intriguingly, one cell line showed biallelic expression and chromatin relaxation of the Pgk-1 locus, suggesting that the relaxation occur regionally on X chromosome.

Alleles↗
PubMed1998

Short-term in vivo evaluation of small-diameter vascular prosthesis composed of segmented poly(etherurethane)/2-methacryloyloxyethyl phosphorylcholine polymer blend.

A small-diameter vascular prosthesis with potential for clinical use was prepared from a Dacron prosthesis coated with nonthrombogenic polymeric materials. As a coating material, segmented poly(etherurethane) (SPU; Tecoflex 60) was blended with a phospholipid polymer, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, which has excellent blood compatibility. The Dacron prosthesis, 2 mm in diameter, was immersed in a solution of the SPU/MPC polymer blend and dried to evaporate the solvent. The SPU/MPC polymer prosthesis was nonwater permeable and could be sewn to a natural vessel by a microsurgical technique. The SPU solution was used instead of the SPU/MPC polymer blend solution to prepare a control prosthesis (SPU prosthesis). The SPU/MPC polymer prosthesis and the SPU prosthesis were placed as interposition grafts in rabbit carotid arteries. A massive red thrombus became attached to the surface of the SPU prosthesis as early as 90 min after implantation. In the SPU/MPC polymer prosthesis case, the surface was maintained clear even after 5-day implantation. These observations indicated that the MPC polymer in the SPU could improve the nonthrombogenicity of SPU, and the SPU/MPC polymer blend had potential for preparation of small-diameter vascular prostheses.

Animals↗
PubMed1998

Enhanced melanogenesis induced by tyrosinase gene-transfer increases boron-uptake and killing effect of boron neutron capture therapy for amelanotic melanoma.

Specific and powerful cancer killing effect for melanoma by boron neutron capture therapy (BNCT) using DOPA analogue, 10B-p-boronophenylalanine (10B-BPA), has been established, but amelanotic melanoma is insufficiently responsive to 10B-BPA BNCT in comparison with actively melanin-producing melanoma. Although the accumulation mechanism of 10B-BPA within melanoma was not established, we have recently obtained findings suggesting that melanin monomers, key intermediates for melanin polymer formation, play a critical role in 10B-BPA accumulation. In addition, there are some kinds of human amelanotic melanomas, such as MEL2A, in which expression of tyrosinase is repressed or lacking though tyrosinase-related protein (TRP)-1 and TRP-2 are well expressed. Thus, by using a similarly tyrosinase-lacking mouse amelanotic melanoma cell line, A1059, we constructed TA1059 cells by transfecting human tyrosinase-cDNA into these cells. TA1059 cells acquired higher DOPA-oxidase and DOPAchrome tautomerase activity as well as eumelanin content at even higher levels than those of B16F10 cells. TA1059 cells showed about 2.5 times higher P-boronophenylalanine (BPA) uptake than A1059 cells in culture. In animal experiments, by using these cell lines, tumor growth of TA1059 was significantly suppressed by 10B-BPA BNCT as compared with A1059. These findings indicate that the induction of active melanin biosynthesis by melanogenic gene-transfer effectively improves the treatment of amelanotic melanoma by BNCT.

Animals↗
PubMed1998

Comparison of calculated nasal resistance from Röhrer's equation with measured resistance at delta P150Pa.

Values of nasal resistance at delta P150Pa have been recommended by the International Standardization Committee for clinical use. However, this point seems somewhat high for quiet nasal breathing. To determine the usefulness of calculated nasal resistance at delta P150Pa from Röhrer's equation when transnasal pressure fails to reach the point, the values at delta P150Pa calculated from the method have been compared with actually measured nasal resistances at delta P150Pa by active anterior rhinomanometry with a nasal nozzle. The mean value of measured unilateral nasal resistance in 75 patients is 0.513 +/- 0.511 Pa/cm3/s on expiration and 0.335 +/- 0.193Pa/cm3/s on inspiration. The mean value of calculated nasal resistance from Röhrer's equation is 0.511 +/- 0.515Pa/cm3/s on expiration and 0.337 +/- 0.207Pa/cm3/s on inspiration. Correlations between measured and calculated nasal resistances have been assessed and are almost identical in both expiration and inspiration. Calculated nasal resistance at delta P150Pa from Röhrer's equation seems to be suitable for evaluation when transnasal pressure fails to attain the point.

Adolescent↗
PubMed1997

Pairing of DNA fragments containing (GGA:TCC)n repeats and promotion by high mobility group protein 1 and histone H1.

Tandemly repeated DNA sequences of (GGA:TCC)n are found in tracts up to 50 base pairs long, dispersed at thousands of sites throughout the genomes of eukaryotes. Here we demonstrate the formation of complexes paired between two DNAs containing such repeats in vitro and show enhancement of the pairing by glutathione S-transferase fusion proteins of high mobility group protein 1 and histone H1. This assembly depends on incubation time at 37 degrees C and concentrations of the proteins and DNA, and the enhancement is inhibited by distamycin and actinomycin D interacting DNA through the minor groove. Structure of the DNA-DNA complex is deduced by comparison of its mobility in gel electrophoresis with those of synthetic markers of heterotetramers. Three synthetic and genomic DNA fragments containing repeats that have different arrangements exhibit different efficiencies of DNA pairing, implying that the pairing is affected by the number of repeat units and the arrangement of repeats in a sequence. Intriguingly, pairing occurs between homologous fragments but not between heterologous DNAs among the three. These results suggest that the repeat-mediated DNA pairing plays a role in organization of higher order architecture of chromatin and possibly chromosome segregation requiring sequence-specific association events of DNA molecules.

DNA Fragmentation↗
PubMed1997

Biologic activity of proteoglycan macrophage colony-stimulating factor.

We compared the biologic activities of 85-kDa macrophage-CSF (85-kDa M-CSF), which is fully active, and a proteoglycan M-CSF (PG-M-CSF). Both originate from the same precursor, but the latter retains the carboxyl-terminal portion, which must be proteolytically removed from the precursor to generate 85-kDa M-CSF and which is uniquely modified by a chondroitin sulfate glycosaminoglycan chain. PG-M-CSF supported the formation of murine macrophage colonies such as 85-kDa M-CSF. Furthermore, PG-M-CSF stimulated the proliferation of murine bone marrow macrophages, an M-CSF-dependent murine cell line, and an M-CSF-responsive human cell line established by transfer of the human M-CSF receptor gene. PG-M-CSF and 85-kDa M-CSF had equivalent specific biologic activities on a molar basis in all bioassays. The activity of PG-M-CSF was not affected by enzymatically removing the glycosaminoglycan chain when assayed by the formation of macrophage colonies and proliferation of the bone marrow macrophages. We analyzed the phosphorylation on tyrosine residue(s) of the M-CSF receptor in response to these M-CSFs that trigger mitogenic responses. PG-M-CSF rapidly (within 10 min) induced receptor phosphorylation in human cells with the same potency as 85-kDa M-CSF. These results indicate that PG-M-CSF is not a latent form or precursor of 85-kDa M-CSF but a fully biologically active cytokine.

Animals↗
PubMed1997

Difference in HMG1-induced DNA bending among microsatellites.

Sequence-dependency of high-mobility group protein (HMG) 1-induced DNA bending is examined for microsatellites using a circularization assay which can measure the extent of bending. Fragments of 133 bp containing (GGA/TCC)11 in the middle showed greater bending than those harboring (GAA/TTC)11 and (GT/AC)17 repeats, and fragments possessing (GA/TC)17 exhibited only slight bending. Differences were not detected for fragments having the repeats near the end. Filter binding assays showed no difference in their binding affinity, suggesting that GGA/TCC repeats are more flexible than the other three repeats as concerns HMG1-induced bending. These results suggest that the mammalian genomes comprise flexible and inflexible regions of microsatellites which might play roles in chromatin architectures and in dynamic packaging of genomic DNA during the cell division cycle.

Chromatin↗
PubMed1997

Perforation of acalculous cholecystitis associated with localized atherosclerosis: report of a case.

We describe herein the unusual case of a 68-year-old Japanese man who underwent laparotomy for an acute abdomen caused by diffuse peritonitis, which revealed perforation of the gallbladder without any stones. A cholecystectomy was subsequently carried out, and histological examination showed marked atherosclerosis of the gallbladder associated with acute inflammatory changes. It is most likely that circulatory disturbance of the gallbladder wall due to the atherosclerosis played an important role in the events leading to perforation. Acute acalculous cholecystitis is an uncommon condition which is extremely difficult to diagnose preoperatively. The clinicopathological features of this patient are of particular interest and importance in terms of pathogenesis as well as treatment.

Acute Disease↗
PubMed1997

Effect of IL-6 on tumor cell invasion of vascular endothelial monolayers.

The effect of interleukin-6 (IL-6) on the invasive capacity of B16-F1 mouse melanoma cells into vascular endothelial monolayers was examined, and an in vitro assay system for the quantitative determination of tumor cell invasiveness, using confocal microscopy with a fluorescence image analyzer, was developed. First, the invasive capacity of B16-F1 mouse melanoma cells against bovine vascular endothelial monolayers was estimated; then, the gap junctional intercellular communication (GJIC) of endothelial cells was examined. Treatment of endothelial cells with IL-6 resulted in a remarkable increase in the invasion of tumor cells into the endothelial monolayer, which was found to be significant from 25 ng/ ml, and peaked at levels of more than 50 ng/ml. This stimulatory effect of IL-6, which was observed from 3 h after the initiation of treatment and lasted for up to 24 h, was abolished by the addition of the anti-IL-6 antibody. Although phase-contrast microscopy did not reveal any morphological changes in the endothelial cells following treatment with 25-200 ng/ml IL-6 for 24 h, the GJIC was observed to be significantly decreased. These findings indicate that the invasive capacity of tumor cells into endothelial cells is affected by IL-6.

Analysis of Variance↗
PubMed1997

In vivo diagnosis of human malignant melanoma with positron emission tomography using specific melanoma-seeking 18F-DOPA analogue.

Detection and diagnosis of human malignant melanoma by Positron Emission Tomography (PET) using 18F-10B-L-BPA, a specific melanogenesis-seeking compound synthesized for use in Boron Neutron Capture Therapy for malignant melanoma (NCT), has been developed. This resulted in a novel, highly effective methodology for the selective three dimensional imaging of metastatic malignant melanomas, and for accurate determination of 10B concentration in the tumor and surrounding tissue, providing almost all diagnostic information necessary for complete non-invasive radiation dose planning in the treatment of malignant melanoma both for NCT as well as other therapeutic modalities.

Boron↗
PubMed1997

Telomerase activity and metastasis: expansion of cells having higher telomerase activity within culture lines and tumor tissues.

Tumor cells with metastatic potential may have a high telomerase activity that augments telomeric DNA repeats, allowing the cells to escape from the inhibition of cell proliferation due to shortened telomeres. We examined the expression level of telomerase activity using the telomeric repeat amplification protocol among a series of cell lines obtained by repeated transplantation of a mouse fibrosarcoma. The lines could be grouped into three; one has no metastatic potential, and the other two show metastatic abilities after intravenous or subcutaneous injection. Comparison of their telomerase activity indicated that more malignant lines had higher activity. A similar relation was seen in metastatic nodules formed through clonal expansion from the heterogeneous population of inoculated cells; clonality was monitored in terms of variable patterns of subtelomeric repeats. The results suggest that a high level of telomerase activity may not be requisite for metastasis, but may confer a propensity to dominate in a tumor tissue.

Animals↗
PubMed1997

[From vascular surgery to gastrointestinal surgery].

From the basic and clinical study of the peripheral vascular disturbance, my interest has gradually focused on the visceral circulation, following the first experience of an acute bowel gangrene. Thereafter, I have investigated acute mesenteric ischemia and ischemic enterocolitis both clinically and experimentally. Furthermore, I have also noticed on the combined vascular resection for the malignancies of the gastrointestinal organs. Finally, I have discussed on the role of newly introduced vascular intervention for the gastrointestinal disorders. Further development in many fields will surely lead to great possibility in the future.

Gastroenterology↗
PubMed1997

[A case of lumbosacral lipoma-associated adult onset tethered cord syndrome with initial symptoms of sensory disturbance and intractable foot ulcers].

A 63-year-woman who complained of sensorimotor disturbance of the lower extremities and urinary disturbance was presented. She noted loss of superficial sensation in both feet and foot ulcers at the age of 20 years. Her illness was initially diagnosed as hereditary sensory neuropathy type 1 (HSN1). The foot ulcers were so intractable that she had to have her right leg amputated at the age of 48 years. She had a severely impaired superficial sensation in the lower extremities and buttock, distal weakness of the left leg, and dysuria at the age of 60 years. The neurological examination revealed that she had segmental sensorimotor disturbance below the levels of the 5th lumbar segment. MRI demonstrated tethered cord with a lumbosacral lipoma. Adult onset tethered cord syndrome (TCS) that presents with HSN 1-like symptoms as initial clinical features has not yet been reported. Foot ulcers are often seen in child onset TCS in which the degree of tethered cord is severer than adult onset cases. It is reported that release of the tethered cord promotes healing of the foot ulcers. We recommend MRI for the study of the lumbosacral cord of patients with HSN 1-like symptoms, because there is a possibility that such patients may have TCS and early surgical treatment is effective for TCS.

Charcot-Marie-Tooth Disease↗
PubMed1997

[A case of cortical reflex positive-negative myoclonus--electrophysiological study].

An 11-year-old girl who had the positive-negative myoclonus and the history of the generalized tonic clonic seizure was electrophysiologically studied. She had no siblings with either myoclonus or epilepsy, and her intellectual level was normal. She had no other neurological deficits including ataxia, pyramidal and extrapyramidal signs. Surface EMG showed a brief increase in the EMG activity followed by the silent period associated with positive and negative myoclonus during sustained wrist extension. Giant SEP and C reflex (38.6 ms) following electric stimulation of the median nerve at the wrist were obtained in the resting condition and the silent period (about 180 ms) following C reflex was obtained during voluntary contraction. Jerk-locked back averaging of the EEG time-locked to the onset of the myoclonic discharge recorded from the right biceps muscle showed a cortical spike at the left central region preceding the myoclonus onset by 12.6 ms. The latency of C reflex in this case was very short compared with that of previously reported cortical reflex myoclonus. The estimated cortical delay between the arrival of the somatosensory volley and the motor cortex discharge responsible for the C reflex was -1.0 ms and this value was shorter than that in patients with typical cortical reflex myoclonus (mean 3.7 +/- 1.1 ms). Conditioning stimuli (C) of the right median nerve at the wrist started to facilitate the amplitude of the motor evoked potential recorded from the right abductor pollicis brevis muscle after magnetic test stimuli (T) of the left motor cortex at 20 ms of the C-T interval. This C-T interval was shorter than that (24.6 +/- 1.6 ms) in patients with the typical cortical myoclonus. These electrophysiological findings suggested the shorter reflex pathway of the cortical reflex myoclonus in this case than in typical cortical reflex myoclonus. We speculated that the myoclonus was based upon the direct sensory projection from the thalamus to the motor cortex in this case.

Child↗
PubMed1996

A novel activity of HMG domains: promotion of the triple-stranded complex formation between DNA containing (GGA/TCC)11 and d(GGA)11 oligonucleotides.

The high mobility group protein (HMG)-box is a DNA-binding domain found in many proteins that bind preferentially to DNA of irregular structures in a sequence-independent manner and can bend the DNA. We show here that GST-fusion proteins of HMG domains from HMG1 and HMG2 promote a triple-stranded complex formation between DNA containing the (GGA/TCC)11 repeat and oligonucleotides of d(GGA)11 probably due to G:G base pairing. The activity is to reduce association time and requirements of Mg2+ and oligonucleotide concentrations. The HMG box of SRY, the protein determining male-sex differentiation, also has the activity, suggesting that it is not restricted to the HMG-box domains derived from HMG1/2 but is common to those from other members of the HMG-box family of proteins. Interestingly, the box-AB and box-B of HMG1 bend DNA containing the repeat, but SRY fails to bend in a circularization assay. The difference suggests that the two activities of association-promotion and DNA bending are distinct. These results suggest that the HMG-box domain has a novel activity of promoting the association between GGA repeats which might be involved in higher-order architecture of chromatin.

Base Composition↗