Biomedical subjects

Y Miki

Publications and source records attributed to Y Miki.

At least 73 records · Page 4Linked to original sources

PubMed1998

Cloning of TCFL5 encoding a novel human basic helix-loop-helix motif protein that is specifically expressed in primary spermatocytes at the pachytene stage.

We have isolated a novel human gene that is expressed specifically in primary spermatocytes in the testis. The cDNA contains an open reading frame of 1356 bp, encoding a 452-amino-acid protein that includes a basic Helix-Loop-Helix (bHLH) motif. The gene, which was mapped to chromosome region 20q13.3-->qter by fluorescence in situ hybridization, consists of six exons and spans approximately 24 kb of genomic DNA. Immunohistochemical staining located the gene product exclusively in cell nuclei of primary spermatocytes at the pachytene stage, but not in those at the leptonema stage. We named this gene TCFL5 (transcription factor-like 5, basic helix-loop-helix). The cell-type and stage-specific expression of TCFL5 indicates that this protein may function in a crucial role in spermatogenesis as a transcription factor by regulating cell proliferation or differentiation of cells through binding to a specific DNA sequence like other bHLH molecules.

Animals↗

PubMed1998

Isolated U-fiber involvement in MS: preliminary observations.

We studied the frequency and location of isolated U-fiber involvement in MS and correlated these findings exploratively with physical disability and neuropsychological impairment. Fifty-three MS patients were examined. Three-millimeter-thick, fast spin-echo T2-weighted MR images and spin-echo postgadolinium T1-weighted images were obtained. Computer software that which had been validated previously for quantitation of MS lesions was used to detect lesions on the T2-weighted images. The Expanded Disability Status Scale (EDSS), Ambulation Index (AI), and a battery of neurocognitive tests were performed on each patient. Forty-two arcuate hyperintensities along the U-fiber were detected by the software in 28 patients (53%). Twenty-seven lesions (64.3%) were seen in the frontal lobe, eight (19.0%) in the temporal lobe, three (7.1%) in the parietal lobe, three (7.1%) in the occipital lobe, and one (2.4%) in both frontal and parietal lobes. Four lesions (9.5%) showed gadolinium enhancement. Seventeen lesions (40%) were hypointense on the T1-weighted images. Scores of three of the 11 neuropsychological tests reflecting performance in executive control and memory were significantly different at least at the p = 0.05 level between the eight patients with multiple, isolated U-fiber lesions and the 45 patients without any or with only a single U-fiber lesion. No significant difference was noted for EDSS or AI. Isolated U-fiber involvement is an underappreciated MR finding in MS. Our preliminary hypothesis is that U-fiber lesions may contribute to neuropsychological impairment, although our observation requires confirmation.

Adult↗

PubMed1998

Correlation of volumetric magnetization transfer imaging with clinical data in MS.

We examined the relations between quantitative volumetric estimates of cerebral lesion load based on magnetization transfer imaging (MTI), clinical data, and measures of neuropsychological function in 44 patients with clinically diagnosed MS. In this population we assessed the correlation between several volumetric MTI measures, measures of neurologic function (Kurtzke Expanded Disability Status Scale and Ambulation Index), and disease duration using Spearman's correlation coefficient. Patients were classified on the basis of neuropsychological test performance as severely impaired, moderately impaired, and normal. We assessed differences between these groups with respect to MTI results using the Kruskal-Wallis test. MTI measures corrected for brain volume were found to correlate with disease duration (p < 0.01) and showed suggestive correlations with measures of neurologic impairment (p < 0.05). Individual neuropsychological tests correlated with MTI measures corrected and not corrected for brain volume (p < 0.001). An MTI measure not corrected for brain volume differed (p < 0.05) between severely impaired, moderately impaired, and normal patients. These preliminary results suggest that volumetric MTI analysis provides new measures that reflect more accurately the global lesion load in the brain of MS patients, and they may serve as a method to study the natural course of the disease and as an outcome measure to evaluate the effect of drugs.

Adult↗

PubMed1998

Multiple possible sites of BRCA2 interacting with DNA repair protein RAD51.

To investigate the biological consequences of aberrant BRCA2 protein during mammary carcinogenesis, we attempted to identify proteins that normally interact with BRCA2. By using a yeast two-hybrid system with a hybrid protein that contained residues 639-1,508 of BRCA2 protein fused to the GAL4 DNA-binding domain, we isolated five independent cDNA clones that encoded parts of RAD51 protein, a human homolog of bacterial RecA. In vitro experiments using anti-RAD51 antibody confirmed interaction of BRCA2 with RAD51. The RAD51-binding region of BRCA2 detected in the present study was distinct from the region reported recently. Further studies using smaller portions of BRCA2 defined at least two additional RAD51-binding domains, residues 982-1,066 and 1,139-1,266. Our results suggest that BRCA2 can interact with RAD51 through multiple sites of BRCA2 and that control of mitotic and meiotic recombination and/or of genomic integrity through binding to RAD51 may be a crucial mechanism by which BRCA2 suppresses abnormal proliferation of mammary cells.

Amino Acid Sequence↗

PubMed1997

Clinicopathological Features of Hereditary Breast Cancer.

The possible role of germline mutations of BRCA1 and BRCA2 as causative agents of familial breast cancer was assessed. Their possible involvement in the carcinogenesis of hereditary breast cancer was investigated using 63 clinically suspect families. Twenty-one lineages (33.3%) had mutations in one of the two BRCA genes. This relatively low incidence suggested that germline mutations in unknown genes are involved in the carcinogenesis of hereditary breast cancer in the Japanese population. However, the clinicopathological features characteristic of hereditary breast cancer, such as early disease onset, a high incidence of bilateral breast cancer, and a high incidence of multiple primary carcinomas in other organs were confirmed in the present study.

Journal Article↗

PubMed1997

Hyperlipidemia enhancement of renal preneoplasia but not tumor formation is due to elevated apoptosis in the Eker rat.

The influence of a high-fat diet on the appearance of renal tumors was assessed in the Eker rat model of hereditary renal carcinoma. Examination of H&E-stained sections showed a significant increase in the number of microscopic solid adenomas in the high-fat group compared with the low-fat group, whereas there was no significant difference in the number of macroscopic tumors between the two groups. Where had the tumor buds gone? Staining for apoptotic bodies occasionally revealed apoptosis in and around the microscopic adenomas. In addition, an Eker rat renal tumor-derived cell line showed apoptosis when it was cultured with high concentrations of native and acetylated low-density lipoprotein. These findings suggested that tumor buds repeatedly appeared and disappeared in Eker rats on a high-fat diet.

Adenoma↗

PubMed1997

Use of a binary mixture of quaternary ammonium salts in fluorometric determination of glycosaminoglycans.

The concentration of glycosaminoglycans, in an aqueous solution was determined by observing the fluorescent intensity of the ion of 2-hexadecyl-9H-pyrido[4,3b]indole at 450 nm by irradiating 253-nm light after dissolution of the insoluble salt in ethanol, which was formed by the reaction between a solution of a sample of glycosaminoglycan and an aqueous solution of the binary mixture of fluorescent 2-hexadecyl-9H-pyrido[4,3b]indolium bromide and hexadecyl pyridinium chloride. The fluorescent quaternary ammonium salt, which was slightly soluble in water, was solubilized in water by forming mixed micelles with a nonfluorescent soluble quaternary ammonium salt. The present method showed good linearity for the calibration curves between 5 and 1000 micrograms/ml in all samples of glycosaminoglycan except keratan sulfate. The relative standard deviation in determination was less than 3% for the whole calibration range.

Chondroitin Sulfates↗

PubMed1997

Cloning and functional expression of a novel glucuronyltransferase involved in the biosynthesis of the carbohydrate epitope HNK-1.

The HNK-1 carbohydrate epitope is characteristically expressed on a series of cell adhesion molecules and also on some glycolipids in the nervous system over a wide range of species from insect to mammal. The HNK-1 epitope is involved in cell-cell and/or cell-substrate interaction and recognition during the development of the nervous system. In this study, we isolated a novel glucuronyltransferase from rat brain, which is a key enzyme of the biosynthesis of the HNK-1 epitope on glycoproteins. Based on the partial amino acid sequences, we isolated cDNA encoding the glucuronyltransferase. The primary structure deduced from the cDNA sequence predicted a type II transmembrane protein with 347 amino acids and had no detectable similarity with any other proteins of known functions, including glucuronyltransferases of the liver and olfactory epithelium. Expression of a soluble recombinant form of the enzyme in COS-1 cells produced an active glucuronyltransferase. The selective expression of the glucuronyltransferase gene in the nervous system was consistent with the almost exclusive localization of the HNK-1 epitope in the nervous system. Transfection of the glucuronyltransferase cDNA into COS-1 cells induced not only expression of the HNK-1 epitope on the cell surface but also marked morphological changes of the cells, suggesting that the HNK-1 epitope associates with the cell-substratum interaction.

Amino Acid Sequence↗

PubMed1997

New method for incorporating solvent influence into the evaluation of X-ray scattering intensity of proteins in solution.

A new method, the surface integration method, is presented for taking into account the influence of solvent on the intensity of X-ray scattered from proteins in solution. It requires no averaging numerically over the solute orientation. The solvent is modeled by a continuous medium with electrons of uniform density. This method is applied to amino acids, peptides and native proteins to confirm its effectiveness. The solvent influence on the normalized scattering intensity I(K) I(0) is more noticeable for larger solutes and at larger scattering angles, where I(K) is the intensity of scattered X-ray with the magnitude of scattering vector K.

Journal Article↗

PubMed1997

Laparoscopic diagnosis of blunt abdominal trauma in children

This study evaluates the safety and role of laparoscopy in the diagnosis of blunt abdominal trauma in children. Laparoscopy was performed in five patients aged 3 to 13 years because of persistent abdominal pain after blunt trauma. A laparotomy was not indicated from the physical examination, laboratory data, or radiologic findings. With the patient under general anesthesia, a 10-mm trocar was inserted through the umbilical fossa and the intra-abdominal organs were observed for 10 - 60 min under an insufflation pressure of 10 - 12 mmHg. The patients remained hemodynamically stable without pneumothorax development. Three patients underwent laparatomies: one, who had blood in the omental sac, had a duodenal injury with hemorrhagic necrosis and underwent a resection; one with ascites and high amylase levels had an injury of the main pancreatic duct and underwent resection of the pancreatic tail; and one who had fresh blood in the upper abdomen and Douglas' pouch had a splenic hemorrhage and underwent hemostasis. The other two had serous or serosanguinous ascites and recovered without surgery. In patient 1, the same amount of information might have been obtained from a barium study. In patient 2, the pancreatic transection might have been diagnosed from ascites shown on serial computed tomograms. Patient 3 might also have been treated successfully non-surgically. It hus appears that laparoscopy may be a safe diagnostic method for blunt abdominal trauma in children, however, this small series has yielded insufficient information to assess its usefulness in making the diagnosis and the decision for laparotomy. Further studies are required to ascertain whether it will make any significant difference in the form of management.

Journal Article↗

PubMed1997

Necrotizing enterocolitis in a term infant with coarctation of the aorta complex.

Necrotizing enterocolitis (NEC) sometimes occurs in term infants with congenital heart disease. This article reports a rare case of a term infant with coarctation of the aorta complex who developed NEC on the 8th day after birth. Spontaneous closure of the ductus arteriosus in the 1st week of life may cause intestinal ischemia and hypoxia with resultant NEC.

Aortic Coarctation↗

PubMed1997

Laparoscopic cholecystectomy and time-course changes in renal function. The effect of the retraction method on renal function.

BACKGROUND: Recently, the retraction method has been used to reduce intraabdominal pressure (IAP) during laparoscopic surgery. The purpose of this study was to determine the serial changes in renal function during laparoscopic cholecystectomy (LC) using the retraction method. METHODS: Urine output, effective renal plasma flow (ERPF), and glomerular filtration rate (GFR) were measured serially in seven patients who underwent LC with 12 mmHg pneumoperitoneum (High-IAP group) and five who underwent LC using the retraction method with 4 mmHg pneumoperitoneum (Low-IAP group). RESULTS: Urine output, ERPF, and GFR were decreased during pneumoperitoneum in the High-IAP group, whereas no significant changes in any of these parameters were observed in the Low-IAP group. CONCLUSIONS: Our findings demonstrate that reduction of IAP to 4 mmHg using the retraction method prevents the transient renal dysfunction caused by prolonged 12 mmHg pneumoperitoneum during LC, suggesting that the retraction method reduces the risk of perioperative renal dysfunction during laparoscopic surgery.

Adult↗

PubMed1997

The change of periapical exudate prostaglandin E2 levels during root canal treatment.

We have previously demonstrated that detectable levels of prostaglandin E2 exist in periapical exudates (PE-PGE2) from root canals of periapical periodontitis. Our data from a cross-sectional study also suggested the association of PE-PGE2 concentrations with the active phase of periapical lesions. The objective of this study was to investigate the longitudinal changes of PE-PGE2 levels during root canal treatment. Periapical exudate specimens were quantitatively sampled from root canals of 20 nonvital teeth at consecutive treatment visits to measure PGE2 concentrations. The mean PE-PGE2 levels significantly decreased following the endodontic therapy (158.0 +/- 54.1 pg/microliter in the first samples versus 48.4 +/- 37.9 pg/microliter in the second samples). A significant correlation was also found between the changes in PE-PGE2 levels and the clinical disease expression of periapical periodontitis (p < 0.01). Decreased PGE2 production is considered to reflect the remission of disease activity. These results suggest the central roles of PGE2 in regulatory mechanisms for the expression of periapical disease.

Dental Pulp Cavity↗

PubMed1997

Non-random ionic-charge distribution responsible for the structural stability and molecular recognition of proteins.

The 'ionic-charge shuffling method' is presented to generate a complete set of electrostatic mutants for a natural protein where ionic charges on the molecular surface of the template protein are exhaustively interchanged with each other. Total Coulomb interaction energies are evaluated for all of the mutants by numerically solving the finite difference Poisson-Boltzmann equation and their distribution in the ensemble is obtained. This method has been applied to five natural proteins to reveal that they have a significantly lower Coulomb energy than the average over the ensemble of their mutants. It is also shown that these natural proteins have a significantly larger and smaller number of pairs of attractive and repulsive ionic groups, respectively, than those expected for their randomly shuffled ensemble: They have been 'designed' through molecular evolution so that a pair of ionic charges with opposite signs may have a higher tendency to be located close to each other, while a pair with the same sign are away from each other.

Ions↗

PubMed1997

Protein stability; optimization of electrostatic contributions by partially neutralizing surface ionic charges.

'Partial Charge-Neutralization Method' is developed to study influence of the relative amount of positive and negative charges in proteins on their structural stability. A given number of either positively or negatively charged groups are neutralized in all of their possible combinations to generate a whole set of distinct species. The Coulomb energy of each species is calculated by numerically solving the Poisson-Boltzmann equation for aqueous solutions. Partial neutralization of lysine residues of tuna cytochrome c in aqueous solution at neutral pH with the Debye-Hückel screening parameter kappa = 1 nm-1 reproduces qualitatively well the destabilization of acetylated cytochrome c observed in physicochemical measurements at pH 7. The stabilization of its molten globule state at pH 2 is also studied with the present method. It is shown that the electrostatic contribution to the structural stability of natural proteins can be optimized by changing the difference in number of their positive and negative charges.

Cytochrome c Group↗

PubMed1997

Multiple sclerosis lesion quantification using fuzzy-connectedness principles.

Multiple sclerosis (MS) is a disease of the white matter. Magnetic resonance imaging (MRI) is proven to be a sensitive method of monitoring the progression of this disease and of its changes due to treatment protocols. Quantification of the severity of the disease through estimation of MS lesion volume via MR imaging is vital for understanding and monitoring the disease and its treatment. This paper presents a novel methodology and a system that can be routinely used for segmenting and estimating the volume of MS lesions via dual-echo fast spin-echo MR imagery. A recently developed concept of fuzzy objects forms the basis of this methodology. An operator indicates a few points in the images by pointing to the white matter, the grey matter, and the cerebro-spinal fluid (CSF). Each of these objects is then detected as a fuzzy connected set. The holes in the union of these objects correspond to potential lesion sites which are utilized to detect each potential lesion as a three-dimensional (3-D) fuzzy connected object. These objects are presented to the operator who indicates acceptance/rejection through the click of a mouse button. The number and volume of accepted lesions is then computed and output. Based on several evaluation studies, we conclude that the methodology is highly reliable and consistent, with a coefficient of variation (due to subjective operator actions) of 0.9% (based on 20 patient studies, three operators, and two trials) for volume and a mean false-negative volume fraction of 1.3%, with a 95% confidence interval of 0%-2.8% (based on ten patient studies).

Algorithms↗

PubMed1997

Infrequent mutation of the H-cadherin gene on chromosome 16q24 in human breast cancers.

To investigate the molecular basis of altered expression of the H-cadherin gene, we used polymerase chain reaction-single strand conformation polymorphism and DNA sequencing to examine the H-cadherin gene in 48 primary breast cancers in which loss of the long arm of chromosome 16 had been detected. We identified no mutations other than somatic 5-bp deletion within the coding region in a single tumor. The very low frequency of mutation found in these experiments suggests that H-cadherin is usually not a primary target for carcinogenesis in human breast cancers, and that reduction of its expression is likely to be a consequence of some other genetic event(s).

Breast Neoplasms↗

PubMed1997

Effects of basic fibroblast growth factor on human periodontal ligament cells.

In order to clarify the regulatory mechanisms of periodontal regeneration by basic fibroblast growth factor (bFGF), effects of bFGF on proliferation, alkaline phosphatase activity, calcified nodule formation and extracellular matrix synthesis of human periodontal ligament (PDL) cells were examined in this study. bFGF enhanced the proliferative responses of PDL cells in a dose-dependent manner. The maximum mitogenic effect of bFGF on PDL cells was observed at the concentration of 10 ng/ml. In contrast, bFGF inhibited the induction of alkaline phosphatase activity and the mineralized nodule formation by PDL cells. Moreover, employing the reverse transcription-polymerase chain reaction (RT-PCR) technique, we observed that the levels of laminin mRNA of human PDL cells was specifically upregulated by bFGF stimulation, but that of type I collagen mRNA was downregulated. On the other hand, the expression of type III collagen and fibronectin mRNA were not altered even when the cells were activated by bFGF. These results suggest that suppressing cytodifferentiation of PDL cells into mineralized tissue forming cells, bFGF may play a role in wound healing by inducing growth of immature PDL cells and that in turn accelerates periodontal regeneration.

Alkaline Phosphatase↗