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Biomedical subjects

Yuichi Yokoyama

Publications and source records attributed to Yuichi Yokoyama.

17 recordsLinked to original sources
PubMed2006

AMF/G6PI induces differentiation of leukemic cells via an unknown receptor that differs from gp78.

Autocrine Motility Factor (AMF)/maturation factor (MF)/neuroleukin (NLK) is a multifunctional protein, which acts as a glucose 6-phosphate isomerase (G6PI) intracellularly. Exto-G6PI stimulates invasion and metastasis of tumor cells, neurotropic growth and differentiation of leukemic cells. The cell motility and proliferation receptor is known to be gp78 (78 kilo-Dalton glycoprotein), which has seven transmembrane domains in its N-terminal region, but the maturation factor receptor remains unclear. The human acute monocytic leukemia line does not express gp78 and its motile activity is not enhanced by AMF though it is well differentiated by AMF exposure. The forced expression of gp78 in leukemic cells recovered acceptable motile stimulation, concomitant with reduced differentiation ability. Two unknown proteins were detected by crosslinking between AMF and leukemic cells. The results of this report suggest that the receptor molecule for AMF/NLK/MF in leukemic differentiation is not gp78.

Animals↗
PubMed2005

Chronic effects of AJ-9677 on energy expenditure and energy source utilization in rats.

The effects of AJ-9677 on metabolic parameters were examined in rats that had or had not been chronically treated with this beta3-adrenoceptor agonist. A challenge administration of AJ-9677 increased both the temperature of brown adipose tissue and energy expenditure in both groups of rats. However, whereas the former effect was subject to desensitization, the latter effect was augmented by prior chronic administration of AJ-9677. Whereas a challenge administration of AJ-9677 induced a decrease in the respiratory quotient that persisted for at least 15 h in rats pretreated with vehicle, the initial decrease in this parameter lasted for only 4 h in rats pretreated with AJ-9677. These results suggest that, in rats subjected to chronic treatment with AJ-9677, a challenge administration of this drug increased energy expenditure by stimulation not only of fat oxidation but also of glucose oxidation.

Acetates↗
PubMed2005

Inducible production of alcohol oxidase and catalase in a pectin medium by Thermoascus aurantiacus IFO 31693.

Thermoascus aurantiacus showed the best growth on medium containing pectin as a carbon source. The enzyme involved in the production of catalase in the fungus was alcohol oxidase. Formaldehyde dehydrogenase and formate dehydrogenase, in addition to alcohol oxidase and catalase, were detected in the cells grown on pectin. Alcohol oxidase was alkali resistant (pH 7 to 11), and was comparatively heat stable (55 degrees C).

Alcohol Oxidoreductases↗
PubMed2005

Purification and characterization of intracellular and extracellular, thermostable and alkali-tolerant alcohol oxidases produced by a thermophilic fungus, Thermoascus aurantiacus NBRC 31693.

Intracellular and extracellular alcohol oxidases (AO int and AO ext) were purified from the liquid and solid cultures of a thermophilic fungus, Thermoascus aurantiacus NBRC 31693, as electrophoretically and isoelectrophoretically homogeneous proteins, respectively. Both enzymes contained a flavin adenine dinucleotide (FAD) cofactor and were stained with Schiff's reagent. The molecular weight of AO int was estimated to be about 320 kDa and its subunit was 75 kDa. The molecular weight of AO ext was about 560 kDa, and it was composed of two types of subunits (75 kDa and 59 kDa). The pIs of AO int and AO ext were 5.88 and 6.08, respectively. AO int and AO ext were stable up to 60 degrees C and 55 degrees C, respectively. The enzymes were stable over a wide range of pH from 6 to 11. AO int oxidized short straight-chain alcohols (K(m) for methanol, 13.5 mM and K(m) for ethanol, 15.8 mM). On the other hand, AO ext could oxidize secondary alcohols and aromatic alcohols (veratryl alcohol and benzyl alcohol) in addition to straight-chain alcohols (K(m) for methanol, 0.5 mM and K(m) for ethanol, 10.2 mM).

Alcohol Oxidoreductases↗
PubMed2004

Non-multiple lymphomatous polyposis form of mantle cell lymphoma in the gastrointestinal tract.

Mantle cell lymphoma (MCL) comprises 2.5%-7% of all non-Hodgkin's lymphomas, and the gastrointestinal tract is involved in about 20% of cases. Multiple lymphomatous polyposis (MLP) is an uncommon disease that is regarded as the intestinal form of MCL. We present a rare case of gastrointestinal MCL without MLP, and demonstrate that rituximab was effective for the treatment of this patient. A 61-year-old man presented with continuous diarrhea and hematochezia for a period of 5 months. Superficial lymph nodes were not palpable, but both tonsilla were enlarged. The level of soluble interleukin (IL)2-receptor was 3480 U/ml (normal <500 U/ml). Colonoscopy showed diffuse redness with erosion, without observation of any venous capillary, with these findings continuing from the rectum to the ileum. Upper gastrointestinal endoscopy showed a slightly rough gastric mucosal surface, and chicken-skin like mucosa was observed in the second portion of the duodenum. Small-to-medium size lymphoma cells were seen histologically from the tonsilla to the rectum. The lymphoma cells were immunohistochemically positive for CD5, CD20, CD79a, and cyclin D1. Polymerase chain reaction analysis revealed a chromosomal translocation t(11;14)(q13;q32) in the bcl-1 gene. We diagnosed this as a case of MCL from these findings. For treatment, the patient received a total of ten courses of combination chemotherapy consisting of cyclophosphamide (1000 mg), doxorubicin (70 mg), vincristine (2 mg) and prednisolone (50 mg) (CHOP), which led to a partial remission. However, 2.5 years later, massive infiltrations of the lymphoma cells were found in the colon and stomach. As the infiltrating lymphoma cells expressed CD20 molecules on their surfaces, the patient was treated with a chimeric anti-CD20 monoclohal antibody, rituximab, which showed significant efficacy, and a second partial remission was achieved.

Antibodies, Monoclonal↗
PubMed2004

Co-existence of early esophageal carcinoma and leiomyoma: a case report.

There have been several reports of co-existing esophageal squamous cell carcinoma and esophageal submucosal tumor. However, there is no previous report describing a submucosal tumor located within an area of early esophageal cancer. This report presents the case of a 64-year-old man who developed early esophageal cancer with leiomyoma situated within the lesion in the upper third of the esophagus. Since leiomyoma existed within the area of the esophageal cancer, it was misdiagnosed as a component of esophageal cancer and the depth of esophageal cancer invasion was overdiagnosed by endoscopic ultrasonography. Therefore, surgery was chosen as treatment for esophageal cancer. If the leiomyoma had been diagnosed correctly as a submucosal tumor by endoscopy and endoscopic ultrasonography, an endoscopic mucosal resection would have been the therapeutic procedure of choice for an esophageal tumor.

Carcinoma, Squamous Cell↗
PubMed2003

Analysis of K-ras codon 12 mutation in flat and nodular variants of serrated adenoma in the colon.

PURPOSE: The developmental process of serrated adenomas is obscure, and the importance of genetic alterations has not been elucidated clearly. The possibility that the developmental process and genetic alterations of serrated adenomas could differ from those of ordinary tubular adenomas was explored in this work. METHODS: Serrated adenomas were obtained by endoscopic resection (n = 57) and divided into two groups: flat (n = 10) and nodular (n = 47). Mutation of the K-ras gene was analyzed by enriched polymerase chain reaction-enzyme-linked mini-sequence assay, which can detect not only the presence of a mutation but also the mutation type of K-ras codon 12 with high sensitivity. Methylation-specific polymerase chain reaction was performed with specific primers for the DNA repair gene O6-methylguanine-DNA methyltransferase. RESULTS: Serrated adenomas located in the rectum were more likely to have a K-ras mutation (9/12, 75 percent), whereas serrated adenomas of the flat type were less likely to have one (1/10, 10 percent). Furthermore, nodular serrated adenomas that occurred in the rectum possessed a high frequency of K-ras gene codon 12 point mutation (8/10, 80 percent) despite an overall frequency of 46.8 percent (22/47). A mutation of the K-ras codon 12 gene was detected in 23 (40.4 percent) of 57 serrated adenomas. Three types of point mutations of codon 12 were detected, with the mutation of GAT being observed most frequently. CONCLUSIONS: This study shows that development of nodular serrated adenomas may depend on the mutation of the K-ras codon 12 gene, whereas development of flat serrated adenomas may not. Additionally, serrated adenomas that occur in the rectum are closely related to the mutation of the K-ras codon 12 gene. K-ras mutations in serrated adenomas may be unaffected by the epigenetic silencing of O6-methylguanine-DNA methyltransferase by promoter hypermethylation.

Adenoma↗
PubMed2003

A rare case of idiopathic retroperitoneal fibrosis involving obstruction of the mesenteric arteries, duodenum, common bile duct, and inferior vena cava.

Idiopathic retroperitoneal fibrosis (IRF), usually affects the ureter, although the biliary tree, duodenum and vasculature may also be susceptible. This case report describes a 64-year-old man with IRF, who presented painless watery diarrhea, radiological features of obstructive jaundice and duodenal obstruction, and ultimately an obstruction of the inferior vena cava. We employed tamoxifen for his treatment, but the disease progressed and the patient died of multiple organ failure two years after the onset. While the cause of IRF in this patient was obscure, we suspected his painless watery diarrhea indicated chronic ischemia of the small bowel, and the findings of an abdominal CT scan were extremely valuable in indicating IRF.

Angiography↗
PubMed2002

Pit pattern and three-dimensional configuration of isolated crypts from the patients with colorectal neoplasm.

BACKGROUND: This study examined the usefulness of magnifying videoscopic pit-pattern diagnosis in the differential diagnosis of colonic neoplasms. The relationship between pit patterns and the three-dimensional configuration of the neoplastic gland was evaluated for its contribution toward an understanding of pit patterns. METHODS: A total of 3005 colorectal lesions were examined endoscopically and histopathologically. Pit patterns were classified into six types. All materials used for crypt isolation were derived from segments of 21 colorectal lesions and one normal colonic mucosa. For the crypt isolation, the HCl-digestion method was used. RESULTS: The magnifying videoscopic diagnosis was comparable with the histological diagnosis in the 3005 colorectal lesions. Isolated crypts with the type-I pit pattern resembled a test-tube; the type-II pit pattern was also tubular, but had observed fissures at the bottom; the type-III l pit pattern was a reversed triangle or tongue-like in shape; and the type-III s pit pattern was columnar and either tapered off or meandered. Isolated crypts with the type-IV b pit pattern appeared as long reversed triangles with protuberances, and the type-IV v pit pattern was flat with slender tubules or finger-like processes. The isolated crypts with the type-V pit pattern were complicated and indistinct in shape. CONCLUSIONS: Evaluation of the three-dimensional configuration revealed that when the pit patterns, of each isolated crypt differed, their three-dimensional configurations also differed. Recognition of the differences in the three-dimensional configuration should contribute toward both an understanding of pit-pattern diagnosis and the further development of the endoscopic diagnosis of various colorectal lesions.

Adenoma↗
PubMedDate not supplied

Myosin isoform expression and MAFbx mRNA levels in hibernating golden-mantled ground squirrels (Spermophilus lateralis).

Hibernating mammals present many unexplored opportunities for the study of muscle biology. The hindlimb muscles of a small rodent hibernator (Spermophilus lateralis) atrophy slightly during months of torpor, representing a reduction in the disuse atrophy commonly seen in other mammalian models. How torpor affects contractile protein expression is unclear; therefore, we examined the myosin heavy-chain (MHC) isoform profile of ground squirrel skeletal muscle before and after hibernation. Immunoblotting was performed first to identify the MHC isoforms expressed in this species. Relative percentages of MHC isoforms in individual muscles were then measured using SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). The soleus and diaphragm did not display differences in isoforms following hibernation, but we found minor fast-to-slow isoform shifts in MHC protein in the gastrocnemius and plantaris. These subtle changes are contrary to those predicted by other models of inactivity but may reflect the requirement for shivering thermogenesis during arousals from torpor. We also measured mRNA expression of the Muscle Atrophy F-box (MAFbx), a ubiquitin ligase important in proteasome-mediated proteolysis. Expression was elevated in the hibernating gastrocnemius and the plantaris but was not associated with atrophy. Skeletal muscle from hibernators displays unusual plasticity, which may be a combined result of the intense activity during arousals and the reduction of metabolism during torpor.

Animals↗