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Biomedical subjects

M Kikuchi

Publications and source records attributed to M Kikuchi.

At least 541 records · Page 30Linked to original sources
PubMed1994

Replacement of both tryptophan residues at 388 and 412 completely abolished cytochalasin B photolabelling of the GLUT1 glucose transporter.

A mutated GLUT1 glucose transporter, a Trp-388, 412 mutant whose tryptophans 388 and 412 were both replaced by leucines, was constructed by site-directed mutagenesis and expressed in Chinese hamster ovary cells. Glucose transport activity was decreased to approx. 30% in the Trp-388, 412 mutant compared with that in the wild type, a similar decrease in transport activity had been observed previously in the Trp-388 mutant and the Trp-412 mutant which had leucine at 388 and 412 respectively. Cytochalasin B labelling of the Trp-388 mutant was only decreased rather than abolished, a result similar to that obtained previously for the Trp-412 mutant. Cytochalasin B labelling was finally abolished completely in the Trp-388, 412 mutant, while cytochalasin B binding to this mutant was decreased to approx. 30% of that of the wild-type GLUT1 at the concentration used for photolabelling. This level of binding is thought to be adequate to detect labelling, assuming that the labelling efficiency of these transporters is similar. These findings suggest that cytochalasin B binds to the transmembrane domain of the glucose transporter in the vicinity of helix 10-11, and is inserted covalently by photoactivation at either the 388 or the 412 site.

Animals↗
PubMed1994

Cloning and sequencing of hen magnum cDNAs encoding vitelline membrane outer layer protein I (VMO-I).

Two cDNAs encoding hen vitelline membrane outer layer protein I (VMO-I), which is classified as a new type of multi-beta-sheet assembly, were cloned and sequenced. Northern blot analysis using vmo-I cDNA as a probe showed the presence of three mRNA species. Strikingly, expression of these mRNAs was restricted to a specific region of the hen oviduct, the area joining the infundibulum to the magnum.

Amino Acid Sequence↗
PubMed1994

Dermatofibroma: superficial fibrous proliferation with reactive histiocytes. A multiple immunostaining analysis.

BACKGROUND: Dermatofibroma (DF) is a superficial form of benign fibrous histiocytoma, composed of a mixture of fibroblastic cells and histiocytic cells. The histogenesis of this lesion is a matter of controversy. METHODS: Forty-five cases of DF were investigated by single and multiple immunostaining techniques, using panel of 12 antibodies including proliferating cell nuclear antigen (PCNA), vimentin, and macrophage/histiocyte markers (HAM56 and CD68). RESULTS: Double immunostaining demonstrated that 58% of the DF cells simultaneously expressed PCNA and vimentin, whereas only 5% were PCNA+/HAM56+, and 2% were PCNA+/CD68+. By triple-stain for PCNA, vimentin, and HAM56, 56% of the DF cells were PCNA+/vimentin+/HAM56-, but only a few cells were PCNA+/HAM56+/vimentin+/-. Of the PCNA positive cells, 88% were vimentin+HAM56- and 10% were HAM56+ vimentin-/+. The cells positive for CD68 showed similar distribution to that of HAM56+ cells, though there were fewer of the former than the latter in most cases. These results suggest that the majority of the proliferating cells in DF express vimentin but not histiocytic markers. Morphologically, the PCNA+/vimentin+/HAM56- (or CD68-) cells exhibited a spindle-shaped configuration resembling fibroblasts, whereas most of the HAM56+/CD68+ cells possessed abundant rounded cytoplasm and were similar to normal histiocytes. CONCLUSIONS: The present study suggests that the proliferative compartment of DF cells is composed chiefly of mesenchymal/fibroblastic lineage, accompanied by varying numbers of normal reactive histiocytes.

Adolescent↗
PubMed1994

A common ancestry for multiple catalytic antibodies generated against a single transition-state analog.

Immunization with a single haptenic transition-state analog generates a few catalytic antibodies among the dozens of antibodies capable of binding the hapten. The diversity of the immune response has raised some fundamental issues, such as How do catalytic and noncatalytic antibodies differ on a structural basis? To address this issue, the variable region primary sequences of 11 antibodies (including 6 catalytic and 5 noncatalytic antibodies) elicited against a single haptenic transition-state analog were deduced from cDNA sequences. Cluster analyses using phylogenetic trees constructed by the neighbor-joining method have revealed that the amino acid sequences of noncatalytic antibodies bear no relationship to one another, while the catalytic antibodies share significant structural identity. Furthermore, no catalytic antibodies possessing amino acid sequences with high homology to those of noncatalytic antibodies were detected. Five catalytic antibodies examined showed 89-95% and 74-84% sequence homologies in the complete light- and heavy-chain variable regions, respectively. Thus, it seems likely that the catalytic antibodies elicited against a single hapten use the canonical set of variable region genes. Interestingly, one catalytic antibody showed only limited sequence similarity to the other catalytic antibodies and was found to exhibit a distinctly different substrate specificity. From the broad range of their binding constants to the hapten, it is unlikely that highly homologous catalytic antibodies are generated as a result of simple high-affinity choices. These results emphasize the utility of rationally designed transition-state analogs for the induction of antibody molecules with catalytic activity.

Amino Acid Sequence↗
PubMed1994

Hepatocellular carcinoma after transcatheter hepatic arterial embolization. A histopathologic study of 84 resected cases.

BACKGROUND: Recently, transcatheter arterial embolization (TAE) has been used to treat hepatocellular carcinoma (HCC), yet much is still unknown regarding its optimal use. METHODS: Eighty-four patients with HCC after TAE underwent surgical resection. Fifty of the tumors were less than 3 cm (small HCC [S-HCC]), and 34 were 3 cm or larger (large HCC [L-HCC]). Necrosis rate, distribution of residual HCC, histopathology of the main tumor, and proliferating activity of residual HCC by means of proliferative cell nuclear antigen (PCNA) were examined. Twenty-two randomly selected patients with HCC treated with standard chemotherapy were used as non-TAE control subjects. RESULTS: A necrosis rate of greater than 95% was seen in 35 cases of S-HCC and in 15 of L-HCC. All five nonencapsulated tumors were L-HCC and had a much lower necrosis rate. No tumors in the control group showed a necrosis rate of greater than 95%. Encapsulated tumors were categorized according to their tumor interiors, capsules, and extracapsular zones. Complete necrosis of the tumor interior was 80.0% and 35.3% in S-HCC and L-HCC, respectively. Viable residual tumors were found mainly in the extracapsular zone in S-HCC, whereas in L-HCC they were located primarily in the tumor interior. Most capsules were affected by tumor necrosis and the subsequent healing process, resulting in a thick secondary capsule. Tumor interior necrosis was uniform and coagulative in S-HCC, in contrast to L-HCC, in which necrotic regions comprised several necrosis units of differing texture and were divided by fibrous septa. In contrast, the control group revealed spotty, sparse necrosis. Non-TAE tumor capsules were thin and pathologically characteristic of those naturally occurring in tumors, as opposed to the thick fibrous capsules, which are inducible by TAE therapy. In the TAE group, the PCNA positivity rates were 37.5%, 52.5%, and 100% in Grades 1, 2, and 3/4 combined, respectively. At the tumor-nontumor boundary of the extracapsular region, PCNA-positive cells were detected in 55.0% of the cases. CONCLUSIONS: The thickened tumor capsule serves as a good postoperative indicator of TAE response. Small tumors seem to be affected in the tumor interior, whereas extracapsular invasion undermines the TAE effect. PCNA was helpful in detecting the tumor-nontumor boundary and useful as a parameter of viability of HCC after TAE.

Adolescent↗
PubMed1994

Expression of adult and fetal natural killer cell markers in sinonasal lymphomas.

The majority of sinonasal non-Hodgkin's lymphomas (NHLs) are thought to originate from T-cell lineage. However, they often express natural killer (NK)-cell markers so that their origin still remains obscure. In this study, cell type of sinonasal NHLs were characterized by immunohistochemical and Southern blot analyses. We examined nine patients with sinonasal NHL. Six patients with tonsillar or pharyngeal non-B-cell lymphomas served as a control group. Immunohistochemical study showed that all nine cases of sinonasal NHL were CD56+CD2+, whereas controls were CD56-CD2+. According to the rearrangement of T-cell receptors (TCRs) and expression of CD3 markers, the sinonasal NHL cases were classified into three groups: TCR-CD56(Leu-19)+CD3(Leu4)- NHL (three patients), TCR-CD56+CD3+ NHL (five patients), and TCR+CD56+CD3+ NHL (one patient). In contrast, control patients' NHLs were TCR+CD56-CD3+. These results imply that eight cases of TCR-CD56+ sinonasal NHL are of NK-cell lineage. Among these eight cases, TCR-CD56+CD3+ cases (five of eight patients) were rather similar to the phenotype of fetal NK cells. From these results, the majority of sinonasal NHLs seem to originate from varying maturation stages of NK-cell lineage.

Adult↗
PubMed1994

Site-specific O-glycosylation of cell adhesive lysozyme in yeast.

The cell adhesive protein RGD8 has been constructed using a yeast expression system by inserting eight amino acid residues (TGRGDSPA) between Val74 and Asn75 of human lysozyme [Yamada et al. (1993) J. Biol. Chem. 268, 10588-10592]. Purified RGD8 from yeast culture supernatant was found to contain glycosylated variants, in addition to the unglycosylated form. Peptide mapping analyses suggested that the glycosylation occurred at the inserted Thr residue in the RGD8 molecule. Electrospray ionization mass spectrometric analysis demonstrated the presence of four or five hexose residues in the glycosylated variants. Only mannose was detected in the sugar analysis of the oligosaccharide mixture obtained by mild alkaline treatment of the variants, and the structures of these carbohydrate chains were identified as Man alpha 1-3Man alpha 1-2Man alpha 1-2Man alpha and Man alpha 1-3Man alpha 1-3Man alpha 1-2Man alpha 1-2Man alpha by 1H-NMR spectroscopy. No other glycosylation was found, although the RGD8 molecule possesses a total of 13 Thr and Ser residues. In addition, no O-glycosylation was observed when the RGD8 protein was expressed in mouse L-cells. Thus, this O-glycosylation looks specific for yeast and the site of the Thr residue. The O-glycosylated variants of RGD8 exhibited a high level of adhesion activity to baby hamster kidney cells, which was almost comparable to that of the unglycosylated form.

Amino Acid Sequence↗
PubMed1994

Protein disulfide isomerase associates with misfolded human lysozyme in vivo.

Wild-type human lysozyme (hLZM) is quantitatively secreted into the media when expressed in mouse fibroblast cells, but some misfolded hLZMs are retained and rapidly degraded in a pre-Golgi compartment (Omura, F., Otsu, M., Yoshimori, T., Tashiro, Y., and Kikuchi, M. (1992) Eur. J. Biochem. 210, 591-599). To detect the association with misfolded hLZMs of cellular proteins involved in their folding, retention, and pre-Golgi degradation, a co-precipitation experiment was carried out using anti-hLZM antibody and metabolically labeled cell lysates, which were treated with a membrane-permeable cross-linking reagent. Here we report that protein disulfide isomerase associated in vivo with misfolded hLZMs, but not with the wild-type protein, and discuss the possible role of protein disulfide isomerase in the quality control of newly synthesized proteins in the endoplasmic reticulum.

Amino Acid Sequence↗
PubMed1994

Involvement of two sulfur atoms of protein disulfide isomerase and one sulfur atom of the DsbA/PpfA protein in the oxidation of mutant human lysozyme.

Protein disulfide isomerase (PDI) and the DsbA/PpfA protein catalyze the oxidation of mutant human lysozyme, L79CC81A, which has two native disulfide bonds, Cys6-Cys128 and Cys30-Cys116, a non-native Cys79-Cys95, and 2 free cysteine residues at positions 65 and 77. Oxidation of L79CC81A (R-form) yielded two isomers, L79CC81A-a (A-form) with tandem-linked Cys65-Cys77 and Cys79-Cys95, and L79CC81A-b (B-form) with cross-linked Cys65-Cys79 and Cys77-Cys95 (Kanaya, E., Ishihara, K., Tsunasawa, S., Nokihara, K., and Kikuchi, M. (1993) Biochem. J. 292, 469-476). PDI mainly enhanced the formation of the A- form in the absence of oxidized glutathione (GSSG); however, as the concentration of GSSG increased, it markedly accelerated the formation of the B-form. In contrast, the DspA/PpfA protein mainly enhanced the formation of the A-form, regardless of the presence or absence of GSSG. These results and the presumed spatial locations of Cys65, Cys77, and Cys79-Cys95 in the R-form suggest that 1 of the half-cystine residues in the active site of PDI and the DsbA/PpfA protein can react with 1 of the 2 free Cys residues of the R-form. The dependence on GSSG of the B-form formation with PDI can be explained by the formation of two transient intermolecular disulfide bonds between PDI and the R-form and the attack of GSSG by the resultant thiolate anion of Cys79 or Cys95. The independence of the reaction with the DsbA/PpfA protein from GSSG can be explained by the formation of one transient intermolecular disulfide bond. The possible formation of the two transient intermolecular disulfide bonds involving two sulfur atoms of PDI and 2 cysteine or half-cystine residues of the substrate could explain the high isomerase activity of PDI.

Binding Sites↗
PubMed1994

Overexpression of hexokinase I but not GLUT1 glucose transporter alters concentration dependence of glucose-stimulated insulin secretion in pancreatic beta-cell line MIN6.

The recently established pancreatic beta-cell line MIN6 retains the ability to secrete insulin in response to physiological glucose concentrations. To investigate the role of glucose transport and phosphorylation in glucose-stimulated insulin secretion by beta-cells, MIN6 cells were stably transfected with a rabbit GLUT1 glucose transporter cDNA or a rat hexokinase I cDNA cloned in an expression vector. Overexpression of GLUT1 increased 3-O-methylglucose uptake, but did not alter either glucose utilization or glucose-stimulated insulin secretion. In contrast, clones overexpressing hexokinase I exhibited enhanced glucose-stimulated insulin secretion at glucose concentrations below 10 mM with a concomitant increase in glucose utilization. Maximal insulin secretion as well as the maximal rate of glucose utilization were not altered in these clones. Insulin secretion stimulated by 2-ketoisocaproate, a non-glucose secretagogue, was not affected by hexokinase I expression. These results strongly suggest that the glucose phosphorylating step, but not glucose transport step, regulates glucose-stimulated insulin secretion by modulating the glycolytic rate in the beta-cell.

3-O-Methylglucose↗
PubMed1994

Primary central nervous system lymphomas. Immunophenotypic, virologic, and cytogenetic findings of three patients without immune defects.

BACKGROUND: Primary central nervous system (PCNS) lymphoma is a relatively rare disease, but an increasing incidence is reported. The Epstein-Barr virus (EBV), which is often found in lymphomas of immunocompromised patients, has been implicated in the development of lymphomas. Many cytogenetic analyses of nodal B cell lymphomas have been performed, but few studies on PCNS lymphomas have been reported. METHODS: The detection of EBV genome using the polymerase chain reaction (PCR) method and cytogenetic studies were performed, in addition to histopathologic and immunophenotypic approaches in biopsied tissue from three patients with PCNS lymphoma. Immunosuppressive states and exposure to mutagens were not clear in all patients. RESULTS: Histopathologic examination disclosed a diffuse type of malignant lymphoma in all patients. Immunophenotypic studies revealed B cell phenotype in all patients, two of whom showed positive reaction for CD5. The PCR method revealed no involvement of EBV genome in tumors in any patients. The cytogenetic study showed clonal chromosome abnormalities in all patients, and abnormalities of chromosome 1 (1q21), 6 (-6, 6q15 and 6q21), 7 (-7 and 7p15), and 14 (14q24 and 14q32) were prominent. The t(6;14)(q15;q32) observed in Patient 1 is the first case to be reported in human de novo lymphoma. CONCLUSIONS: These findings indicate that the causative role of EBV in PCNS lymphoma without immune defects is not clear. The cytogenetic findings were similar to those observed in nodal B-cell lymphoma, suggesting that the origin of PCNS lymphoma cells does not differ from nodal B cell lymphoma cells cytogenetically.

Aged↗
PubMed1994

Pituitary adenylate cyclase activating polypeptide is an extraordinarily potent intra-pancreatic regulator of insulin secretion from islet beta-cells.

Insulin secretion from pancreatic islets is controlled by peptides as well as by nutrients. We report here a novel, extraordinarily potent peptidergic regulation of insulin secretion. A 27-residue form of pituitary adenylate cyclase activating polypeptide (PACAP27) as low as 10(-14) to 10(-13) M stimulated insulin release from rat islets in a glucose-dependent manner. PACAP27 also increased cytosolic free Ca2+ concentration ([Ca2+]i) in islet beta-cells. Nitrendipine, a blocker of the L-type Ca2+ channel, abolished both [Ca2+]i and insulin responses. Vasoactive intestinal peptide, a peptide exhibiting 68% amino acid homology with PACAP, also increased [Ca2+]i in beta-cells but only at concentrations in the nanomolar range, indicating that PACAP27 is 4 logs more potent. A 38-residue form of the peptide (PACAP38) stimulated insulin release and increased beta-cell [Ca2+]i in a manner similar to that of PACAP27. PACAP-like immunoreactivity was demonstrated in pancreatic nerve fibers, islets, and capillaries. The results indicate that PACAP is a physiologically occurring peptide in pancreas and that PACAP, in a glucose-dependent manner, activates beta-cells presumably via a high affinity PACAP-selective receptor, raises [Ca2+]i by increasing the activity of L-type Ca2+ channels, and consequently stimulates insulin release. PACAP appears to be by far the most potent insulinotropic peptide known.

Animals↗
PubMed1994

Effect of low-intensity argon laser irradiation on mitochondrial respiration.

We studied influences of low-intensity argon laser irradiation at various wavelengths on mitochondrial respiration in vitro. Isolated guinea pig liver mitochondria were suspended in an isotonic buffer solution (pH 7.4, 37 degrees C). The mitochondrial suspension was introduced into a constant temperature reaction chamber in which an irradiation fiber, a thermocouple, an oxygen electrode, and a stirrer were installed. Under respiratory conditions of state 4, state 3, and uncoupled respiration, mitochondrial oxygen consumption was measured during low-intensity argon laser irradiations at 351nm, 458 nm, and 514.5 nm. The 351 nm and the 458 nm irradiations at 200 mW inhibited uncoupled respiration by 19% and 11%, respectively, and the irradiation at 351 nm inhibited state 3 respiration as well by 10%. In contrast, the 514.5 nm irradiation enhanced both state 3 and uncoupled respiration by 6-7%. Temperature reference experiments indicated that the thermal effect alone could not account for the effects of laser irradiation on mitochondrial oxygen consumption. These results suggest that the 351 nm and the 458 nm laser irradiation may injure the mitochondrial inner membrane, while the 514.5 nm laser irradiation may slightly promote the rate of ATP synthesis.

2,4-Dinitrophenol↗
PubMed1994

Primary osteosarcoma of the uterus: report of a case with immunohistochemical analysis.

Primary osteosarcoma of the uterus is an extremely rare neoplasm, and its immunohistochemical characteristic is unknown. We report a case of osteosarcoma occurring primarily in the uterine corpus of a 67-year-old woman with lower abdominal pain. The excised tumor showed bony inconsistency and histologically displayed a "pure" osteosarcoma of the uterus. Immunocytochemically, the tumor cells were positive for vimentin but negative for epithelial markers. The patient died 4 months after surgery because of developed local recurrence and pulmonary metastases. In conclusion, uterine osteosarcoma differs from malignant mixed Müllerian tumor (MMMT) in biological behavior, macroscopic and histologic features, and immunohistochemical profile. Osteosarcoma shows more aggressive behavior than MMMT, and displays nonpolypoid feature in appearance and no evidence of epithelial differentiation.

Aged↗
PubMed1994

Analysis of herpesvirus genomes in Kikuchi's disease.

We examined the cervical lymph nodes of 30 patients with Kikuchi's disease and 15 patients with non-specific lymphadenitis, using Southern blot analysis and polymerase chain reaction (PCR) to identify human herpesviruses such as Epstein-Barr virus (EBV), cytomegalovirus, herpes simplex virus, and varicella-zoster virus. By Southern blot analysis, no virus DNA was recognized, but 16 of the 30 nodes from patients with Kikuchi's disease and 8 of the 15 nodes from patients with non-specific lymphadenitis showed amplified EBV DNA by PCR.

Adolescent↗
PubMed1994

Budd-Chiari syndrome and Epstein-Barr virus (EBV) associated plasmacytoma in a patient with chronic active EBV infection.

A 42-year-old Japanese man with chronic active Epstein-Barr virus (EBV) infection initially responded to treatment with interleukin-2 (IL-2). Six months later he developed thrombosis in the hepatic veins, and Budd-Chiari syndrome associated with severe hepatic damage was diagnosed. He also developed a solitary EBV-positive plasmacytoma in the right femur. Since these rare complications occurred after long-term IL-2 therapy, the possibility that long-term IL-2 therapy might cause Budd-Chiari syndrome and liver damage as well as EBV-associated plasmacytoma is discussed.

Adult↗