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Biomedical subjects

M Kikuchi

Publications and source records attributed to M Kikuchi.

At least 217 records · Page 12Linked to original sources
PubMed1999

Mutagenicity of 4-nitroquinoline 1-oxide in the MutaMouse.

As part of a collaborative study, the Mammalian Mutagenesis Study Group (MMS), a sub-organization of the Environmental Mutagen Society of Japan (JEMS) conducted mutagenicity tests in MutaMouse. Using a positive selection method, we studied the organ-specificity and time dependence of mutation induction by 4-nitroquinoline 1-oxide (4NQO). A single dose of 4NQO was administered intraperitoneally (7.5 or 15 mg/kg) or orally (200 mg/kg) to groups of male mice. On days 7, 14 and 28 after treatment, we isolated the liver, kidney, lung, spleen, bone marrow, testis and stomach in the intraperitoneal administration experiment and the liver, lung, bone marrow, testis and stomach in the oral administration experiment. In addition, we performed the peripheral blood micronucleus test to evaluate clastogenicity. In the mice treated intraperitoneally at 7.5 mg/kg, we found increased mutant frequency (MF) only in the lung, where the MF did not vary with expression time. In the mice treated at 15 mg/kg, we found increased MF in the liver, bone marrow and lung. In orally treated mice, the MF was high in the lung and liver and very high in the bone marrow and stomach while the increase in the testis was negligible. As the expression time was prolonged, the MF tended to increase in the liver, decrease in the bone marrow, and remain stable in the lung, testis and stomach. The incidence of micronucleus induction in peripheral blood cells was significantly increased (p<0.01) in the 4NQO groups when compared with the vehicle control group by intraperitoneal treatment. Thus, these assay systems appeared to be of use in detecting not only genetic mutation but also chromosomal aberration.

4-Nitroquinoline-1-oxide↗
PubMed1999

Novel family shuffling methods for the in vitro evolution of enzymes.

It has recently been shown that shuffling of the amino acid sequences of family enzymes allows the generation of improved enzymes. Family shuffling is generally achieved by a DNase I treatment and then by PCR. Shuffling of the xylE and nahH genes, both encoding catechol 2,3-dioxygenases, was carried out by the published method. However, nahH-xylE hybrids were only formed at a very low frequency (less than 1%). Therefore, we developed improved methods for family shuffling by which DNA was cleaved by restriction enzymes instead of by DNase I. With the first improved method, five nahH fragments and five xylE fragments that had been generated by restriction enzyme digestion were subjected to the PCR reactions in two steps, the first being without a primer and the second with a set of primers. This method enabled nahH-xylE hybrid genes to be formed at a high frequency (almost 100%). With the second improved method, nahH and xylE were cleaved by several sets of restriction enzymes, and these digests were then reassembled in two steps. The nahH and xylE DNAs were each cleaved by two (or three) sets of restriction enzymes, and one type of nahH digest and one type of xylE digest were mixed, thus making four (or nine) different mixtures of the nahH and xylE digests. These mixtures were used as templates to carry out PCR without a primer. After the first PCR reaction, all the mixtures were combined, and a second PCR reaction was carried out without a primer. Following these two PCR assembly steps, a third PCR reaction was carried out with two primers to amplify the full-length nahH-xylE hybrid genes. This second method also yielded nahH-xylE hybrids at a frequency of 100%. The degree of recombination of the products with the second method was higher than that with the first method. These methods were used to isolate catechol 2,3-dioxygenases exhibiting relatively high stability at high temperature, one of them being respectively 13- and 26-fold more thermostable than XylE and NahH at 50 degrees C.

Amino Acid Sequence↗
PubMed1999

p85/p110-type phosphatidylinositol kinase phosphorylates not only the D-3, but also the D-4 position of the inositol ring.

Activation of p85/p110-type phosphatidylinositol (PI) kinase has been implicated in various cellular activities. This PI kinase phosphorylates the D-4 position with a similar or higher efficiency than the D-3 position when trichloroacetic acid-treated cell membrane is used as a substrate, although it phosphorylates almost exclusively the D-3 position of the inositol ring in phosphoinositides when purified PI is used as a substrate. Furthermore, the lipid kinase activities of p110 for both the D-3 and D-4 positions were completely abolished by introducing kinase-dead point mutations in their lipid kinase domains (DeltaKinalpha and DeltaKinbeta, respectively). In addition, both PI 3- and PI 4-kinase activities of p110alpha and p110beta immunoprecipitates were similarly inhibited by either wortmannin or LY294002, specific inhibitors of p110. Insulin induced phosphorylation of not only the D-3 position, but also the D-4 position. Indeed, overexpression of p110 in Sf9 or 3T3-L1 cells induced marked phosphorylation of the D-4 position to a level comparable to or much greater than that of D-3, whereas inhibition of endogenous p85/p110-type PI kinase via overexpression of dominant-negative p85alpha (Deltap85alpha) in 3T3-L1 adipocytes abolished insulin-induced synthesis of both. Thus, p85/p110-type PI kinase phosphorylates the D-4 position of phosphoinositides more efficiently than the D-3 position in vivo, and each of the D-3- or D-4-phosphorylated phosphoinositides may transmit signals downstream.

1-Phosphatidylinositol 4-Kinase↗
PubMed1999

Genetic analysis of sorted Hodgkin and Reed-Sternberg cells using comparative genomic hybridization.

Hodgkin and Reed-Sternberg (H and RS) cells are generally considered to be the neoplastic cells of Hodgkin's disease (HD); however, such cells are found only in a minority of HD lesions. Very few data have so far been published on the cytogenetic abnormalities in HD. An analysis of unknown genetic aberrations has only recently become possible through the use of comparative genomic hybridization (CGH), which is based on the competitive binding of tumor and control DNA to metaphase chromosomes. In order to exclude the reaction of non-tumor cells, we used 100 sorted H-RS cells as the tumor DNA, then 100 sorted reactive T cells or B cells as the control DNA. We obtained the amplified DNA, using degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). In addition, to confirm whether or not the lymphocytes in the background were reactive, we performed CGH with 100 sorted B cells and 100 sorted T cells. CGH was thus performed on 9 HDs, including 6 cases of mixed-cellularity (MC) sub-type and 3 cases of nodular-sclerosis (NS) sub-type. CGH of the B and T cells showed no genetic changes in any cases. In contrast, CGH of H-RS cells revealed both gains and losses of DNA in all 9 cases, and multiple changes were also observed. In situ hybridization showed an Epstein-Barr-virus infection in 5 cases of MC; however, no definite relationship was observed between the EBV infection and genetic changes. The most commonly observed genetic aberrations were a loss on 16q11/21 in 6 cases, a gain on 1p13 in 5 cases, and a gain on 7q35/36 in 5 cases. The large number of chromosomal alterations in HD suggests, therefore, that an increased degree of genetic instability play a role in the formation of H-RS cells.

Adult↗
PubMed1999

Interferon-gamma prevents apoptosis in Epstein-Barr virus-infected natural killer cell leukemia in an autocrine fashion.

The significant function of cytokines includes maintenance of cell survival as well as induction of cell differentiation and/or proliferation. We demonstrate here that interferon-gamma (IFN-gamma) plays a role for progression of Epstein-Barr virus (EBV)-infected natural killer cell leukemia (NK leukemia) through maintaining cell survival. NK leukemia cells obtained from 7 patients had clonal episomal forms of EBV, indicating that the leukemic cells were of clonal origin. Although normal NK cells constitutively expressed Bcl-2, the EBV-infected NK leukemia cells lacked endogenous Bcl-2 expression and were hypersensitive to apoptosis in vitro. The addition of IFN-gamma to the culture significantly inhibited their spontaneous apoptosis without inducing cell proliferation or upregulation of Bcl-2. The NK leukemia cells constitutively secreted IFN-gamma, and the patients' sera contained a high concentration of IFN-gamma, levels that were high enough to prevent NK leukemia cells from apoptosis. Bcl-XL was not involved in the IFN-gamma-induced NK leukemia cell survival. These data suggest that the acquisition of IFN-gamma-mediated autocrine survival signals, other than Bcl-2 or BCL-XL, might be important for the development of EBV-infected NK leukemia.

Adolescent↗
PubMed1999

Identification of a SART-1-derived peptide capable of inducing HLA-A24-restricted and tumor-specific cytotoxic T lymphocytes.

We have described the SART-1 gene-encoding peptides recognized by HLA-A2601-restricted and tumor-specific cytotoxic T lymphocytes (CTLs). We now have investigated whether SART-1 encodes peptides capable of inducing the HLA-A24-restricted CTLs. Among the 18 different peptides with HLA-A24-binding motifs, the SART-1(690-698) peptide (EYRGFTQDF) was most strongly recognized by the HLA-A24-restricted and tumor-specific CTLs established from an esophageal cancer patient. After a third stimulation in vitro, this peptide induced HLA-A24-restricted CTLs recognizing the SART-1(259)+ tumor cells in PBMCs of all HLA-A24 homozygous and the majority of HLA-A24 heterozygous cancer patients and healthy donors tested. A similar activity, induction of CTLs from PBMCs, was observed in the Saccharomyces cerevisiae-derived nonapeptide (EYRGFTPMF) that shares 7 amino acids with the SART-1(690-698) peptide. The SART-1(690-698) peptide-induced CTL activity was significantly higher in PBMCs of HLA-A24 homozygotes than in HLA-A24 heterozygotes. The CTL precursor frequency in PBMCs after a third stimulation in vitro with the SART-1(690-698) peptide was high (>1/200) in both cancer patients and healthy donors. The SART-1(690-698) peptide could thus be useful for specific immunotherapy of HLA-A24+ cancer patients.

Antigens, Neoplasm↗
PubMed1999

[Effect of benzene exposure on hematology and hepatic drug metabolic enzymes in ethanol administrated rats].

There are few reports regarding the effects of benzene and ethanol being administered simultaneously. In our experiments with 4 groups (controls, ethanol, benzene and ethanol plus benzene) Wistar male rats were treated with ethanol (20%) for 5 weeks, and then exposed to benzene (0.26 g/kg) for 5 days per week for 3 weeks. We also investigated the effects of benzene on the body weight, organ weight, peripheral hematology and hepatic drug metabolizing enzymes in the ethanol administrated rats. The liver weight increased significantly, but spleen weight decreased significantly in the benzene exposed group. Hematological examination showed a decrease of leukocyte in the two groups of benzene and ethanol plus benzene in comparison with the controls, but an effect promoted by ethanol was not found. Serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) values were not significantly different in the exposure groups when compared with the controls. The contents of microsomal cytochrome P450 in all the exposed groups showed a tendency to increase, but they were not significantly different in comparison with the controls. On the other hand, hepatic glutathione S-transferase activity in the exposed groups increased significantly.

Alanine Transaminase↗
PubMed1999

Sporadic amyotrophic lateral sclerosis of long duration mimicking spinal progressive muscular atrophy: a clinicopathological study.

We report an autopsy case of amyotrophic lateral sclerosis (ALS) clinically diagnosed as spinal progressive muscular atrophy (SPMA). The patient was a Japanese woman without hereditary burden. She developed muscle weakness of the distal part of the left lower extremity at age 42, followed by muscle weakness and atrophy of the right lower extremity and upper extremities. At age 57, she needed transient ventilatory support. Slight weakness in the facial muscles and fasciculation of the tongue appeared at age 60. At age 61, she died of sudden respiratory arrest. During the clinical course, neurological examination revealed neither Babinski signs nor hyperreflexia. The neuropathological examination revealed not only neuronal loss with gliosis in the facial nucleus, hypoglossal nucleus, and anterior horns of the spinal cord, but also loss of Betz cells and degeneration of the pyramidal tracts. Based on these clinicopathological findings and review of literature, we conclude that sporadic ALS mimicking SPMA is present.

Amyotrophic Lateral Sclerosis↗
PubMed1999

The proto-oncogene Bc16 inhibits apoptotic cell death in differentiation-induced mouse myogenic cells.

The Bc16 gene is located at chromosomal band 3q27, a breakpoint for translocation that frequently occurs in B cell lymphomas. Bc16 has been found to be preferentially expressed in germinal center B cells, and expression of this gene has been shown to be essential for germinal center formation in vivo. The physiological function of Bc16 and its role in lymphomagenesis, however, are not yet known. Since significant expression of Bc16 has been demonstrated in skeletal muscle, we have utilized a differentiation-inducible mouse myogenic cell line, C2C12, to elucidate the function of the Bc16 gene product. Expression of Bc16 mRNA was very low in growing myocytes, but was increased in differentiating myocytes cultured in serum-starved medium. Incubation of these cells with cytokines or chemicals that are known to block differentiation suppressed this increased Bc16 message abundance, indicating that Bc16 induction is related to the process of terminal differentiation in muscle cells. While a fraction of myocytes is known to undergo apoptosis after serum-starvation to induce differentiation, adenovirus-mediated overexpression of Bc16 enhanced the viability of the differentiating cells by preventing the apoptosis. High levels of Bc16 antisense mRNA expression induced substantial apoptosis during the differentiation of C2C12 cells, but this was effectively prevented by infection with adenovirus that expressed Bc16 sense mRNA. These results indicate that Bc16 acts to prevent apoptotic cell death in differentiating myocytes. The deregulation of expression of this antiapoptotic gene may also contribute to the development of B cell lymphomas.

Animals↗
PubMed1999

Enhanced phosphoinositide hydrolysis via overexpression of phospholipase C beta1 or delta1 inhibits stimulus-induced insulin release in insulinoma MIN6 cells.

To study the effects of enhanced phosphoinositide hydrolysis on insulin secretion, phosphoinositide-specific phospholipase Cbeta1 (PLCbeta1) or PLCdelta1 was overexpressed in insulinoma MIN6 cells via adenoviral vectors. Inositol phosphate production stimulated by NaF (with AlCl3) in PLCbeta1-overexpressing cells and that stimulated by KCl or glucose in both PLCbeta1- and PLCdelta1-overexpressing cells were greater than that in control cells. In addition, reduced phosphatidylinositol-4,5-bisphosphate levels were observed in these cells stimulated by NaF or KCl. The greater phosphoinositide hydrolysis was accompanied by 25-45% inhibition of insulin secretion. These data suggest that excessive phosphoinositide hydrolysis inhibits secretagogue-induced insulin release in MIN6 cells.

Adenoviridae↗
PubMed1999

B-cell lymphoma of 708 cases in Japan: incidence rates and clinical prognosis according to the REAL classification.

New insights into the pathogenesis of lymphoid malignancies have been gained through novel techniques such as genetic, molecular and immunologic methods. Recently, based on those findings, a new classification system for lymphoid malignancies, known as the REAL classification, has been proposed. To clarify the relation between the histological classification and prognosis of B-cell lymphoid malignancies, we re-classified 708 cases. In all cases, the B-cell phenotype and/or genotype was confirmed by immunohistochemical staining and/or receptor gene analysis. The most common B-cell lymphoma types were diffuse large B-cell lymphoma (58.8%), follicular lymphoma (12.1%), marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) (9.0%) and mantle cell lymphoma (5.9%). Minor types were lymphoblastic lymphoma (3.4%), Burkitt's lymphoma (2.4%), nodal marginal zone lymphoma (2.1%), lymphoplasmacytic lymphoma (2.0%) and plasmacytoma (1.4%). Rare types were prolymphocytic lymphoma and splenic marginal zone lymphoma. Using overall survival rates, the various B-cell lymphoma types could be divided into three broad groups for prognostic purposes: (1) the low risk group consisted of follicular lymphoma, marginal zone lymphoma of MALT, nodal marginal zone lymphoma, plasmacytoma and lymphoplasmacytic lymphoma; (2) the intermediate risk group consisted of diffuse large B-cell lymphoma, Burkitt's lymphoma and mantle cell lymphoma; and (3) the high risk group consisted of lymphoblastic lymphoma. In MALT, the low grade type had a better prognosis than the high grade type. In diffuse large B-cell lymphoma, the common type had a better prognosis than the variant type, which mainly consisted of the immunoblastic lymphoma. The histological classification will have a benefit for the clinical approach.

Adolescent↗
PubMed1999

Survival of patients with HTLV-I-associated lymph node lesions.

Adult T-cell leukaemia/lymphoma (ATLL), is a malignant condition associated with human T-cell leukaemia virus type I (HTLV-I). Usually, although not uniformly, histopathological examination of the lymph nodes shows a pleomorphic type. In addition, some patients with pre-overt ATLL show a Hodgkin's disease-like morphology and lymph nodes in non-neoplastic carriers show features of lymphadenitis. To characterize further the clinicopathological features of HTLV-I-associated lymphadenopathy, the histopathological features of the lymph nodes of 289 patients were classified into five types: lymphadenitis ( n=14), Hodgkin's-like (Hodgkin's) ( n=18), pleomorphic (medium and large cells) ( n=219), pleomorphic small cell ( n=11), and anaplastic large cell (ALC) ( n=27). Survival data were analysed according to the histopathological features of the lymph nodes. The pleomorphic type, which showed typical features of ATLL, was associated with a highly aggressive course and an initially high mortality, followed by a rapid decrease in survival. This pattern was also observed in patients with the ALC type. All cases with lymphadenitis were still alive at the end of the study, while survival progressively decreased in the Hodgkin's type. The small cell type showed an initial rapid decrease in survival followed by a plateau. These results show that the survival trends of patients with pleomorphic and anaplastic lymph node lesions are similar to those with ATL lymphoma, while patients with the lymphadenitis type of lesion were considered to have a non-neoplatic status. There is at present no effective therapy for ATLL, but in the future, these classification and survival data might be useful for the selection of appropriate chemotherapeutic regimens for patients with ATLL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Cell culture test of TCP/CPLA composite.

Thermoplastic polymers filled with a ceramic powder (here described as a "composite") of beta-tricalcium phosphate (TCP) and copoly-L-lactide (CPLA) was prepared by a heat-kneading method. The TCP/CPLA composite obtained had a three-point bending strength of 51.26 +/- 634 MPa, a Young's modulus of 5.18 +/- 1.11 GPa, and a fracture strength of 52.64 +/- 2.975 MPa, which is sufficient for usage as an artificial bone implant material. According to cell culture tests using MC3T3-E1 cells, the TCP/CPLA composite showed no cytotoxicity and the cells were in close contact with the surfaces of the composite without any observable morphological change. These results suggest that a composite consisting of osteoconductive TCP and biodegradable CPLA is suitable as a bioactive artificial bone material.

Absorbable Implants↗
PubMed1999

Forearm heating band used in apheresis therapy that employs a positive-temperature coefficient polymer heater.

For standard apheresis therapy, blood is withdrawn from the ante-cubital vein of one arm and processed blood is returned to a vein of the opposite arm. For low-density lipoprotein apheresis or for the treatment of patients with Guillain-Barré syndrome, a sufficient quantity of blood is readily obtained by this method. In some patients with collagen diseases, however, it may be difficult to secure a reliable vein due to vasospasm or it may not be possible to obtain sufficient blood flow. We constructed a forearm heating band by employing a positive-temperature coefficient heater and evaluated the device to determine whether the application of heat to the forearm is effective in securing a sufficient quantity of blood in those patients with collagen disease (eight with systemic lupus erythematosus and one with multicentric Castleman's disease). Both forearms were heated by using this heating band, in addition to systemic warming with an electric blanket, starting 30 minutes before apheresis. The body surface temperature was sequentially monitored by employing a needle-type thermometer. The surface temperature of the heated area became constant at 37.6+/-0.3 degrees C within approximately 20 minutes (34.7+/-1.3 degrees C at the control site, P<0.001). It was found that this heating band makes it possible to obtain the quantity of blood that is necessary for apheresis and reduce the time required for the treatment. No adverse effects attributable to heating of the forearm were recognized.

Blood Component Removal↗
PubMed1999

Effect of season and photoperiod on FSH in male great tits.

The present study investigated (1) the photoperiodic threshold for an increase in FSH and LH secretion in male great tits (Parus major) from south Sweden and (2) seasonal changes in FSH secretion patterns in short day (SD; 8 L:16 D) and long day (LD; 20 L:4 D) exposed great tits. When fully photosensitive great tits were exposed to a simulated vernal increase in day lengths plasma levels of FSH started to rise at a shorter day length (10.5 h) than did LH (11 h). Once the photoperiodic threshold was exceeded FSH levels increased slowly, but continuously, and reached maximum levels when day lengths had reached 13-14 h, whereas LH levels rose to maximum levels more or less immediately. Great tits break photorefractoriness in September. Exposing sham-operated and castrated great tits to SD or LD in October and February resulted in clear seasonal differences in their FSH cycles. At both times the great tits responded to castration and exposure to long days. However, castration and photoperiodic FSH responses were not only more rapid in February, but also of a higher magnitude.

Animals↗
PubMed1999

Temporal profile of visual evoked responses to pattern-reversal stimulation analyzed with a whole-head magnetometer.

Magnetoencephalography (MEG) has become accepted as a useful method for non-invasively studying brain functions, including visual perception. The present study used MEG to elucidate information processing following pattern-reversal stimulation by analyzing the origins and properties of visual evoked magnetic fields (VEFs). The VEFs of ten healthy adults were recorded in a magnetically shielded room using a 122-channel whole-head magnetometer. The visual stimulation of checkerboard-pattern reversal at 1.7 Hz was presented to the subject's right hemifield. Visual evoked potentials (VEPs) were recorded simultaneously, and 150 responses were each averaged for VEFs and VEPs. For the contrast profile study, pattern-reversal stimuli at five different contrast levels from 96% to 8% were used. In all subjects, the VEFs showed three components with latencies of approximately 95, 120, and 160 ms. The equivalent current dipoles for the first and the third components were located and were oriented close to each other in the left occipital lobe, but these dipoles were separated from that of the second component, which showed an opposite direction. Stimuli at a moderate contrast level markedly reduced the first component, but not the third. These findings indicate that the first and the third components of VEFs appear to originate from anatomically closely situated, almost identical, sources, but that their physiological properties differ.

Adult↗