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Biomedical subjects

M Kasahara

Publications and source records attributed to M Kasahara.

At least 55 records · Page 3Linked to original sources
PubMed2000

Three aromatic amino acid residues critical for galactose transport in yeast Gal2 transporter.

Tyr(446) in putative transmembrane segment 10 (TM10) of the yeast galactose transporter Gal2 has previously been identified as essential for galactose recognition. In the present study, alignment of the amino acid sequences of 63 sugar transporters or related proteins revealed 14 aromatic sites, including Tyr(446) of Gal2, that are conserved in >75% of these proteins. The importance of the remaining 13 conserved aromatic amino acids was examined individually by random mutagenesis using degenerate primers. Galactose transport-positive clones were identified by plate selection and subjected to DNA sequencing. For those transport-positive clones corresponding to Tyr(352), and Phe(504) mutants, all the amino acid substitutions comprised aromatic residues. The importance of the aromatic residues at these sites was further investigated by replacing them individually with each of the other 19 amino acids and measuring the galactose transport activity of the resulting mutants. Among both Tyr(352) and Phe(504) mutants, the other aromatic amino acids supported galactose transport; no other amino acids conferred high affinity transport activity. Thus, at least three aromatic sites are critical for galactose transport: one at the extracellular boundary of putative TM7 (Tyr(352)), one in the middle of putative TM10 (Tyr(446)), and one in the middle of putative TM12 (Phe(504)).

Amino Acids↗
PubMed2000

RecA protein-dependent R-loop formation in vitro.

The RecA protein of Escherichia coli, which has crucial roles in homologous recombination, DNA damage repair, induction of the SOS response, and SOS mutagenesis, was found to catalyze assimilation of complementary RNA into a homologous region of a DNA duplex (R-loop). The reaction strictly requires a region of mismatch in the duplex, which may serve as a nucleation site for RecA protein polymerization. The optimum conditions for the assimilation reaction resemble those for the previously studied RecA protein-catalyzed homologous pairing and strand exchange reaction between two DNA molecules. Our finding lends strong support to the proposal that RecA protein-catalyzed assimilation of a transcript into duplex DNA results in formation of an R-loop at certain regions of the chromosome and that, when stabilized, the R-loop can serve as an origin of chromosome replication.

Adenosine Triphosphate↗
PubMed2000

Analyses of proliferative potential in schwannomas.

We report studies of schwannomas with a high percentage of MIB-1 positive cells. Thirty-eight specimens from 36 cases of schwannoma in the intracranial and spinal regions comprise the substance of this study. The MIB-1 positive cells were measured using immunohistochemical staining. In nine cases with a positivity index (PI) of 5% or more, immunohistochemical staining using DNA topoisomerase IIalpha (topo-II) and CD68 was performed. In some cases, we also searched for apoptosis with the TdT-mediated dUTP-biotin nick-end labeling (TUNEL) method. Three of nine cases with 5% or more positive MIB-1 cells had a very high cellularity with mitotic figures and were considered cellular Schwannomas. Their MIB-1 PI values were 8.21%, 10.00%, and 21.37%. However, the remaining six cases showed little evidence of malignancy. Their PIs were comparatively low, ranging from 5.19% to 8.41%, and the positive findings were localized in many cases. In these cases, we examined the sites where MIB-1 was measured and found that they corresponded to the borderline site between Antoni type A and B patterns and tended to be associated with an infiltration of CD68-positive macrophage. Furthermore, apoptotic cells appeared in the sites. With topo-II staining, the PIs in the same sites of these six cases were low, ranging from 0.78% to 1.93%. This implies that the high MIB-1 PI that was seen in these six cases was caused by reaction of MIB-1 to tumor cells that brought about an abnormality in the cell cycle by degeneration, such as apoptosis. In the site of formation of Antoni type B, MIB-1 may be a false positive in tumors with degenerative findings such as schwannomas. Topo-II was useful in these cases.

Adult↗
PubMed2000

Adenosine and amrinone reverse felypressin-induced depression of myocardial tissue oxygen tension in dogs.

PURPOSE: To determine whether continuous infusion of adenosine triphosphate (ATP), nitroglycerin (NTG) or amrinone (AM) would ameliorate the reductions in coronary blood flow (CBF) and myocardial oxygen tension (PmO2) induced by felypressin. METHODS: Seven open-chest dogs were studied under urethane and alpha-chloralose anesthesia. Hemodynamic variables including heart rate (HR), systolic blood pressure, diastolic blood pressure (DBP), mean pulmonary artery pressure, pulmonary capillary wedge pressure, CBF (ultrasound flowmetry), PmO2(polarography) and cardiac output (thermodilution method) were recorded. Felypressin was infused in a loading dose of 6 mIU x kg(-1) for five minutes and then continued at 0.2 mIU x kg(-1) x min(-1). After 30 min felypressin infusion, each agent was administered for 15 min to evaluate hemodynamic changes. Infusions were 100 and 200 microg x kg(-1) x min(-1) for ATP, 2.5 and 5 microg x kg(-1) x min(-1) for NTG, and 10 and 20 microg x kg(-1) x min(-1) for AM. RESULTS: After felypressin DBP increased by 17 +/- 5 (mean +/- SD) %; CBF decreased by 49 +/- 9%; CI decreased by 40 +/- 13%; HR decreased by 29 +/- 11%; PmO2 in the inner layer decreased by 21 +/- 7%. The Cl and CBF returned to baseline afterATP 100 and 200 microg x kg(-1) x min(-1), AM 10 and 20 microg x kg(-1) x min(-1), but not after NTG. The PmO2 in the inner layer returned to the baseline value by any infusion except for NTG 5 microg x kg(-1) min(-1) CONCLUSION: Adenosine and amrinone, but not nitroglycerin reverses the adverse cardiovascular effects of felypressin.

Adenosine↗
PubMed2000

Metastasis to the forearm skeletal muscle from an adenocarcinoma of the colon: report of a case.

While the liver and lung are primary targets for distant metastasis from colorectal carcinoma, metastasis in other distant sites is rarely found. We report herein an unusual case of metastasis to the skeletal muscle of the right forearm from an adenocarcinoma of the transverse colon. A 60-year-old man was originally admitted to our hospital for surgical treatment of an intestinal obstruction caused by a transverse colon carcinoma. Transverse colon resection along with lymph node dissection was performed and no evidence of distant metastatic foci was found. Angiography-enhanced computed tomography scanning done 14 months after the first operation revealed multiple hepatic metastases which were resected. A metastasis was subsequently detected in the right extensor carpi ulnaris muscle 2 years after the primary resection, and a major part of the right extensor carpi ulnaris and the extensor digiti minimi muscle were resected, warranting a sufficient margin of 5 cm of normal tissue from the tumor. Reattachment of the residual muscles into the ulna was performed. Metastases to bone and/or soft tissues from colorectal carcinomas are extremely rare and to our knowledge, only eight other cases have been reported in the world literature. This low incidence may be related to the anatomical characteristics and/or the biochemical environment of the skeletal muscle, but it is also possible that the true incidence is underestimated. Recent improvements in interventional radiological procedures may facilitate a diagnosis of skeletal muscle metastasis being made more frequently.

Adenocarcinoma↗
PubMed2000

Effect of probucol in a murine model of slowly progressive polycystic kidney disease.

Epithelial proliferation, extracellular matrix remodeling, and interstitial inflammation are central elements in the pathogenesis of slowly progressive polycystic kidney disorders. Probucol, an antioxidant that lowers plasma cholesterol, has been shown to decrease smooth muscle cell proliferation and macrophage accumulation in blood vessels and to prevent restenosis after coronary angioplasty. We determined in 30-day-old male BDF1-pcy hybrid mice (derived from mating DBA/2FG-pcy and C57BL/6FG-pcy) the effect of probucol administered in the diet (1%) for 200 days on kidney weight relative to body weight (KW/BW), cyst expansion, renal interstitial fibrosis, and serum urea nitrogen (SUN) concentration. Animals were fed a moderately high-protein diet (HPD, 36%) to accentuate the development of renal cysts and to promote interstitial fibrosis. Probucol decreased serum cholesterol from 68 to 16 mg/dL but had no effect on food intake or body weight. Probucol decreased relative kidney size from 4.16% +/- 0.55% to 2.64% +/- 0.12% KW/BW (P < 0.01), SUN from 30.5 +/- 1.8 to 25.9 +/- 1.0 mg/dL (P < 0.05), cystic index from 2.45 +/- 0.11 to 1.36 +/- 0.10 (P < 0.01), and fibrosis index from 2.40 +/- 0.11 to 1.82 +/- 0.08 (P < 0.01). We conclude that probucol ameliorates the progressive deterioration in renal function and structure in pcy mice ingesting a relatively high level of dietary protein.

Animals↗
PubMed2000

Expression of topoisomerase II alpha, Ki-67 and p53 in early stage laryngeal carcinomas not featuring vocal cord fixation.

AIM: To determine whether topoisomerase II alpha (topoIIa) expression is an additional prognostic marker for less advanced stage laryngeal cancers first treated without surgery. Ki-67 and p53 protein levels were also assessed for comparison. EXPERIMENTAL DESIGN: Formalin-fixed, paraffin-embedded tumor material from 63 cases of squamous cell carcinoma (SCC) of the larynx (glottis, stages 0,1,2) was immunohistochemically stained for topoIIa, Ki-67 (MIB-1) and p53 (DO-7) and the results were compared with clinicopathologic findings. RESULTS: There were 7 stage 0 (TisN0M0), 33 stage I (T1N0M0), and 23 stage II (T2N0M0) SCCs with the TNM classification. Significant differences between carcinomas and normal mucosa were found for the topoIIa-LI, Ki-67-LI, and topoIIa-to-Ki-67 ratio. Regarding histologic grade, a significant difference in topoIIa-to-Ki-67 ratio was evident between well or moderately and poorly differentiated lesions. There were 19 cases of recurrence and 44 cases of nonrecurrence, but no significant differences were found for either of the indices or their ratio. No significant variation with p53 positivity was evident with reference to histologic differentiation, T-factor, clinical course, or proliferation. CONCLUSIONS: The results demonstrate that the topoIIa-to-Ki-67 ratio is a more sensitive parameter reflecting proliferation, for histologic grading of less advanced laryngeal SCCs, than topoIIa- or Ki-67-LIs.

Adult↗
PubMed2000

Solitary squamous cell papilloma of the lung in a 40-year-old woman with recurrent laryngeal papillomatosis.

A rare case of recurrent respiratory papillomatosis (RRP) is reported with a review of the literature. A 40-year-old Japanese woman had suffered from RRP since 1 year of age. She developed a pulmonary squamous papilloma with a thin-walled cavity, which was suspected as being lung carcinoma. The trachea and bronchi around the tumor were intact, and no malignant transformation was present. Two types of human papillomavirus, 6 and 16, were detected, both in the laryngeal and pulmonary papillomas by in situ hybridization and the polymerase chain reaction method. To date, only 40 cases of juvenile laryngeal papilloma with pulmonary involvement have been reported in the English literature.

Adult↗
PubMed2000

Angiomyomatous hamartoma and associated stromal lesions in the right inguinal lymph node: a case report.

Angiomyomatous hamartoma is a rare disease with a predisposition for the inguinal lymph nodes. A 51-year-old male patient visited a local hospital because of a right inguinal mass, measuring 3 x 4 cm in size, which was resected. The resected specimen showed irregularly distributed thick-walled vessels in the hilum, extending into the medulla and focally into the cortex of the node, eventually becoming more dispersed and associated with smooth muscle cells splaying into sclerotic stroma. These findings are compatible with an angiomyomatous hamartoma. Another tumor-like mass appeared shortly after the resection at the same location, but was not an angiomyomatous hamartoma, rather it was composed of edematous stromal tissue with proliferating smooth muscle cells. The stromal component included thick-walled blood vessels and lymphatics. Although it could not be determined whether these associated changes in the surrounding stroma are a cause or an effect of angiomyomatous hamartoma, they indicate the clinical difficulty in determining an appropriate area of resection and may provide clues to the pathogenesis of angiomyomatous hamartoma.

Actins↗
PubMed2000

Primary primitive neuroectodermal tumor of the kidney.

Primitive neuroectodermal tumor (PNET) is a small round cell sarcoma that mainly develops in the central nervous system and soft tissues of childhood; however recently, primary occurrence of this tumor in the kidney has been reported. We experienced one case of PNET primarily arose in the kidney without metastasis. The patient was a 28-year-old man whose chief complaint was abdominal pain, especially on exercise. On computed tomography scan and magnetic resonance imaging, a solid lesion was found in the left kidney, and a left nephrectomy was performed based on the diagnosis of a tumor in the left kidney. The tumor was within the parenchyma of lower end of left kidney protruding into the abdominal cavity. Histologically, diffuse proliferation of primitive small round cells with rosette formation was found. Immunohistochemically, MIC2 gene product, neuron-specific enolase and S-100 protein were positive. No metastasis to the regional lymph nodes was found. From these observations, the tumor was diagnosed as PNET primarily arising in the left kidney. Although chromosome analysis was not performed, EWS-FLI1 chimera gene was identified by reverse transcriptase-polymerase chain reaction on the freshly frozen specimen and fluorescence in situ hybridization on paraffin sections.

12E7 Antigen↗
PubMed2000

Is extended lymph node dissection necessary for gastric cancer in elderly patients?

OBJECTIVE: To compare the outcome after limited and extended gastric resections to find out whether extended lymph node dissection is indicated for gastric cancer in elderly patients. DESIGN: Retrospective study. SETTING: University hospital, Japan. SUBJECTS: 182 patients over 75 years of age with gastric cancer who had gastric resections from 1980 to 1995. INTERVENTIONS: 161 patients had limited lymph node dissection (limited group) and 21 had extended lymph node dissection (extended group). MAIN OUTCOME MEASURES: Histopathological features, morbidity, mortality, and long-term survival. RESULTS: Postoperative morbidity was 27% (n = 44) in the limited group and 57% (n = 12) in the extended group, and postoperative mortality was 1% (n = 2) in the limited group and 10% (n = 2) in the extended group; these differences are significant (p = 0.005 and p = 0.002). The 5-year survival did not differ significantly between the two groups. Only the T classification and presence of lymph node metastases had a significant influence on the outcome of gastric cancer in elderly patients. CONCLUSIONS: The presence of lymph node metastases is a critical factor in the prognosis of gastric cancer, and extended lymph node dissection has therefore been recommended. However, extended lymph node dissection in elderly patients did not influence the 5-year survival; in addition, the mortality and morbidity in the extended group were higher than in the limited group. Extended lymph node dissection is therefore usually not indicated for gastric cancer in elderly patients.

Gastrectomy↗
PubMed2000

A half-type ABC transporter TAPL is highly conserved between rodent and man, and the human gene is not responsive to interferon-gamma in contrast to TAP1 and TAP2.

TAPL is a half-type ABC transporter with sequence similarity to TAP1 and TAP2 that is transcribed in various rat tissues [Yamaguchi, Y., Kasano, M., Terada, T., Sato, R., and Maeda, M. (1999) FEBS Lett. 457, 231-236]. Primary structures of the human and mouse orthologous counterparts were deduced from cDNAs cloned by means of polymerase chain reaction, and they were compared with that of the rat. The mammalian TAPLs (rat, mouse, and human) are highly conserved, since about 95% of the amino acid residues are identical between rodents and man. Phylogenetic analysis demonstrated that the evolutional rate of TAPL is much slower than those of TAP1 and TAP2, although TAPL could have diverged from an ancestor of TAP1 or that of TAP1 and TAP2. The TAPL-GFP fusion protein transiently expressed in Cos-1 cells was co-localized with PDI, suggesting that TAPL is inserted into endoplasmic reticulum membrane. The conservation of the peptide-binding motifs of TAP proteins in TAPL raises the possibility that the TAPL might be a peptide transporter. The gene for human TAPL is assigned to chromosome 12q24.31-q24.32, while those for TAP1 and TAP2 are located at the MHC locus of chromosome 6p21.!3. Furthermore, the transcription of TAPL gene is not responsive to interferon-gamma, in contrast to TAP1 and TAP2. These results indicate that the gene regulation of TAPL is different from those of TAP1 and TAP2.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Characterization and expression of monosaccharide transporters (osMSTs) in rice.

This study deals with the cloning and characterization of monosaccharide transporter cDNAs in rice. OsMST1-3 (Oryza sativa monosaccharide transporters 1-3) have two sets of putative six transmembrane domains separated by a central long hydrophilic region. Heterologous expression of OsMST3 in the yeast Saccharomyces cerevisiae indicated that OsMST3 has transport activity for some monosaccharides in an energy-dependent H+ co-transport manner. Northern blot and in situ hybridization analyses showed that OsMST3 mRNA is detectable in leaf blades, leaf sheaths, calli and roots, especially the xylem as well as in sclerenchyma cells in the root. These results suggested that OsMST3 is involved in the accumulation of monosaccharides required for cell wall synthesis at the stage of cell thickening.

Amino Acid Sequence↗