Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

At least 343 records · Page 19Linked to original sources

PubMed1998

Alcohol consumption enhances liver metastasis in colorectal carcinoma patients.

BACKGROUND: It is important to identify risk factors for liver metastasis in patients with colorectal carcinoma because the liver is the most common site of recurrence. Alcohol consumption reportedly is associated with hematogenous metastasis in certain animal models. Furthermore, some studies have shown that carmofur, a derivative of 5-fluorouracil, is particularly effective as adjuvant chemotherapy for colorectal carcinoma, and may even suppress liver metastasis, although the mechanism by which this occurs remains unknown. In addition, carmofur is known to inhibit alcohol metabolism. To the authors' knowledge, the relation between liver metastasis in colorectal carcinoma and alcohol consumption has not been examined previously. Therefore, the authors studied the relations between liver metastasis in colorectal carcinoma and various clinicopathologic factors including alcohol consumption status. METHODS: This study was comprised of 133 colorectal carcinoma patients with invasion beyond the submucosal layer who had undergone surgical resection. The subjects were examined and divided into two groups according to the occurrence or absence of liver metastasis. The relations between liver metastasis and other clinicopathologic factors were analyzed by univariate and multivariate statistical methods. RESULTS: Univariate analysis showed alcohol consumption (P=0.0021) and blood vessel invasion (P=0.0045) were correlated with liver metastasis. Multivariate analysis showed both to be independent risk factors for liver metastasis. CONCLUSIONS: Alcohol consumption is an independent risk factor for liver metastasis in colorectal carcinoma patients. Therefore, patients with colorectal carcinoma who drink alcohol require intensive examination and follow-up with respect to liver metastasis. Further study is necessary to confirm the effect of adjuvant chemotherapy using carmofur in colorectal carcinoma patients.

Adult↗

PubMed1998

Selection of DNA binding sites for human transcriptional regulator GATA-6.

The DNA-binding sites for transcriptional regulator GATA-6 were selected and amplified by means of a PCR-mediated random-site selection method involving filter binding and gel-mobility shift analysis using the zinc finger region of human GATA-6 fused with GST. Sequencing and comparison of the selected clones suggested that (A/T/C)GAT(A/T)(A) is the consensus binding sequence, which is similar to the GATA motif (A/T)GATA(A/G) and the gastric motif (G/C)PuPu(G/C)NGAT(A/T)PuPy. GATA-6 also binds to a similar sequence containing the GATC but not the GATG sequence. These results indicated that GATA-6 shows broader sequence specificity as to DNA binding. However, adenine is favored on both sides of the core for strong binding [AGAT(A/T)A], and the order of binding is GATA > GATT > GATC. Full-length human GATA-6 expressed in COS-1 cells showed essentially the same binding specificity, suggesting that the zinc finger region of GATA-6 mainly contributes to the selection of the binding sequence. Furthermore, the non-RI method presented in this paper is convenient for determination of the binding sites of other DNA-binding proteins.

Binding Sites↗

PubMed1998

Analysis of polymerase chain reaction products by high-performance liquid chromatography with fluorimetric detection and its application to DNA diagnosis.

We describe the development of a sensitive high-performance liquid chromatographic (HPLC) method for polymerase chain reaction (PCR) products using bisbenzimide (Hoechst 33258 dye) based fluorimetric detection. The detection limit and specificity for double-strand DNA detection are improved in comparison with HPLC with UV absorbance detection. This HPLC, using a column packed with diethylaminoethyl-bonded non-porous resin particles, was applied to the detection of allele-specific PCR and restriction fragment length polymorphism analysis. We also developed a hybridization method analyzed by HPLC. DNA fragments (149 bp) containing the mutation site (C->A,G,T) in the N-ras gene were amplified by PCR. Fluorescein isothiocyanate (FITC)-labeled DNA probes were also prepared by PCR using FITC-labeled 5' primer. Analysis of mutation was performed by the separation of a hybrid and non-reactive DNA probe with HPLC with fluorimetric detection after the hybridization of target DNA (149 bp) and a FITC DNA probe. The effects of various factors on hybridization were examined to establish optimal assay conditions. Under the conditions determined, a point mutation in PCR products obtained from the N-ras gene could be detected specifically by this method. The analysis of PCR products by HPLC may potentially be useful for DNA diagnosis.

Alleles↗

PubMed1998

Amino acids and peptides. XXXIII. A bifunctional poly(ethylene glycol) hybrid of laminin-related peptides.

A novel amino acid type poly(ethylene glycol) (aaPEG) was prepared and its application as a drug-carrier was examined. The peptides, Pro-Asp-Ser-Gly-Arg (PDSGR) and Tyr-Ile-Gly-Ser-Arg (YIGSR) which are active fragments of Laminin (a cell adhesion protein), were previously reported to be inhibitors of experimental metastasis. Both peptides were conjugated with aaPEG (average molecular weight, 3,000) to prepare a bifunctional peptide-PEG hybrid. The hybrid, PDSGR-aaPEG-YIGSR, was manually prepared by the solid-phase fluorenylmethyloxycarbonyl (Fmoc) strategy. The antimetastatic activity of the peptides in mice was not lost when conjugated to form a larger aaPEG molecule. YIGSR(375 nmol) and PDSGR (375 nmol and 750 nmol) did not demonstrate antimetastatic activity, but a mixture of PDSGR (187 nnmol) and YIGSR (187 nmol) exhibited an inhibitory effect. The inhibitory effect of the hybrid (187 nmol) was more potent than that of the mixture (PDSGR and YIGSR), indicating that the inhibitory effect of the peptides was potentiated by hybrid formation with aaPEG.

Animals↗

PubMed1998

A novel brain-specific isoform of beta spectrin: isolation and its interaction with Munc13.

Munc13 is a component of the neurotransmitter release machinery which is specifically expressed in brain. Munc13 interacts with Doc2 and syntaxin which are also implicated in the neurotransmitter release process. Here we isolated another Munc13-interacting molecule from a rat brain cDNA library by use of the yeast two-hybrid system, identified it to be a novel type of beta spectrin, and named it beta SpIII sigma 1. beta SpIII sigma 1 was specifically expressed in brain, where it was enriched in the synaptic vesicle and plasma membrane fractions. Because spectrin has been shown to interact with the actin cytoskeleton which is involved in the exocytotic process, the present results suggest that the Munc13-beta SpIII sigma 1 interactions play a role in neurotransmitter release.

Amino Acid Sequence↗

PubMed1998

Characterization of fetal serum 5'-nucleotide phosphodiesterase: a novel function as a platelet aggregation inhibitor in fetal circulation.

The study was performed to indicate the ADPase activity of 5'-nucleotide phosphodiesterase (PDEase) from human umbilical cord blood serum and demonstrates the effect of this enzyme on ADP-induced platelet aggregation. The PDEase was purified by using p-nitrophenyl-5'-TMP as a substrate. The PDEase had a molecular weight of 128,000 daltons, and activity of 103 nmol/min/mg protein. The PDEase activity was inhibited by 5'-AMP, ADP, ATP. But 2'-AMP, 3'-AMP, 3':5' cAMP, and adenosine had no inhibiting effects. Kinetic analysis indicated that ADP was a competitive inhibitor with a Ki value of 4.05x10(-5) M. The enzyme was markedly inhibited by 1 mM EDTA. The ADPase activity of the PDEase was 7.79 nmol/min/mg protein. The hydrolized products of ADP by the PDE ase were AMP and phosphoric acid. The platelet aggregation by ADP was inhibited by the addition of the PDEase in the platelet-rich plasma.

Adenosine Diphosphate↗

PubMed1998

Identification of a point mutation associated with a silent phenotype of human serum butyrylcholinesterase--a case of familial cholinesterasemia.

A point mutation which caused a silent phenotype of human serum butyrylcholinesterase (BChE) was identified in the DNA of a 47-year-old Japanese woman who visited our hospital complaining of hypertension. The propositus exhibited an unusually low level of BChE activity, whereas her younger sister and her daughter had intermediate levels of BChE activity and her elder sister a normal level. Immunologically, the amount of BChE protein in the serum of the propositus was normal. DNA sequence analysis of the propositus identified a point mutation at codon 199 (GCA --> GTA), resulting in a Ala --> Val substitution. This alteration is one downstream codon from the catalytic active site (Ser, 198). A family study showed her younger sister and her daughter to have the same mutation.

Blotting, Western↗

PubMed1998

Dual-tracer assessment of coupling between cardiac sympathetic neuronal function and downregulation of beta-receptors during development of hypertensive heart failure of rats.

BACKGROUND: Heart failure is associated with activation of the sympathetic nervous system and downregulation of beta-receptors. However, the coupling between cardiac sympathetic neuronal function and the beta-receptor during the development of hypertensive heart failure is not clear. METHODS AND RESULTS: We determined cardiac neuronal function and beta-receptors with a dual-tracer method of [131I]metaiodobenzylguanidine (MIBG) and 125I-cyanopindolol (ICYP) in Dahl salt-sensitive (DS) and salt-resistant (DR) rats. The rats were fed an 8% NaCl diet after the age of 6 weeks. Blood pressure was raised to >200 mm Hg at 12 weeks in DS rats and remained elevated until 18 weeks, but only slightly in DR rats. Left ventricular (LV) function of DS rats was preserved at 12 weeks but deteriorated at 18 weeks. Despite a 56% reduction of cardiac norepinephrine (NE) content at 12 weeks in DS rats, neither MIBG nor ICYP uptake in DS rats was different from that of DR rats. At 18 weeks, both MIBG and ICYP uptakes decreased, by 52% and 39%, respectively, in association with 71% reduction of cardiac NE, in DS rats. MIBG uptake of the LV was homogeneous at 6 weeks but was lower in the LV endocardial regions at 18 weeks in DS rats. CONCLUSIONS: The present results indicate that cardiac sympathetic neuronal function is relatively preserved at the compensated, hypertrophic stage of DS rats but deteriorates in association with beta-receptor downregulation at the failing stage. The cardiac neuronal dysfunction occurs heterogeneously. A combination of scintigraphic portrayal of beta-receptors with MIBG should provide valuable information regarding sympathetic nerve signaling in living hearts.

3-Iodobenzylguanidine↗

PubMed1998

Citrus auraptene exerts dose-dependent chemopreventive activity in rat large bowel tumorigenesis: the inhibition correlates with suppression of cell proliferation and lipid peroxidation and with induction of phase II drug-metabolizing enzymes.

In our previous short-term experiment, Citrus auraptene inhibited the development of azoxymethane (AOM)-induced aberrant crypt foci, which are precursor lesions for colorectal carcinoma. In the present study, the possible inhibitory effect of dietary administration of auraptene was investigated using an animal colon carcinogenesis model with a colon carcinogen AOM. Male F344 rats were given s.c. injections of AOM (15 mg/kg body weight) once a week for 3 weeks to induce colon neoplasms. They also received diets containing 100 or 500 ppm auraptene for 4 weeks in groups of "initiation" feeding, starting 1 week before the first dosing of AOM. The diets containing auraptene were also given to rats for 38 weeks in groups of "postinitiation" feeding. At the termination of the study (38 weeks), dietary administration of auraptene caused dose-dependent inhibition in AOM-induced large bowel carcinogenesis. Auraptene feeding during the initiation phase reduced the incidence of colon adenocarcinoma by 49% at 100 ppm (P = 0.099) and 65% at 500 ppm (P = 0.0075). Auraptene administration during the postinitiation phase inhibited the incidence of colon adenocarcinoma by 58% at 100 ppm (P = 0.021) and 65% at 500 ppm (P = 0.0075). Also, the multiplicity of colon carcinoma was significantly reduced by initiation feeding at a dose level of 500 ppm (P < 0.01) and postinitiation feeding at a level of 100 and 500 ppm (P < 0.05 and P < 0.01, respectively). Feeding of auraptene suppressed the expression of cell proliferation biomarkers (ornithine decarboxylase activity and polyamine content) in the colonic mucosa and reduced the production of aldehydic lipid peroxidation [malondialdehyde and 4-hydroxy-2(E)-nonenal]. In addition, auraptene increased the activities of Phase II drug-metabolizing enzymes (glutathione S-transferase and quinone reductase) in the liver and colon. These findings suggest that the inhibitory effects of auraptene on AOM-induced colon tumorigenesis at the initiation level might be associated, in part, with increased activity of Phase II enzymes, and those at the postinitiation stage might be related to suppression of cell proliferation and lipid peroxidation in the colonic mucosa.

Aldehydes↗

PubMed1998

Effect of side chain location in (2-aminoethyl)-aminomethyl-2-phenylquinolines as antitumor agents.

Three new derivatives of 2-phenylquinoline having an (2-aminoethyl)aminomethyl group in 7-, 6-, or 4'- (para position of 2-phenyl ring) positions of aromatic system have been prepared. The antitumor activity of these compounds together with 8- or 4- substituted isomers against the HeLa cell is in the order of 8- > 7- > 4- approximately 6- approximately 4'- substituted ones, which is almost in good agreement with that of DNA-binding ability evaluated by means of DNA-titration of UV-VIS spectra, DNA melting experiment, and ethidium displacement assay. Two representative compounds (8- and 4- isomers) are confirmed to have an ability to intercalate into double stranded DNA by topoisomerase I superhelix unwinding assay.

Animals↗

PubMed1998

Design of new inhibitors for cdc2 kinase based on a multiple pseudosubstrate structure.

New inhibitors have been designed for cdc2 kinase based on a multiple pseudosubstrate structure. The new inhibitors have three different structural components: 3,4-bis(indol-3-yl)maleimide, Ac-Cys-(Ser)-Pro-Lys-Lys-NHMe, and ethyloxy group between the two components. Inhibitory activities toward cdc2 and other protein kinases were investigated, and the compound (21) with Ac-Cys-Pro-Lys-Lys-NHMe connected with the triethylene glycol spacer exhibited the most potent inhibition with relatively high selectivity.

Binding Sites↗

PubMed1998

Protein release from collagen matrices.

The effective delivery of protein drugs is an important research subject in the field of pharmacology, and to prolong the effect of protein drugs, many studies are being conducted to control the release of proteins from various carrier materials. Collagen is one of the most useful candidates for this purpose, and many studies have been reported; pharmaceutical formulations containing collagen in gel, film and sponge form are used to incorporate low-molecular-weight compounds such as antibiotics and carcinostatics, and the release of these compounds is controlled by the concentration of the gel as well as the shape and degree of crosslinking of the matrix. However, it is still difficult to retain protein drugs in the collagen. In this article, we report on the controlled release of protein drugs using collagen which exhibits good biocompatibility as a carrier, focusing on a new drug delivery system, the Minipellet, which we have developed.

Journal Article↗

PubMed1998

Autoradiographic determination of local cerebral blood flow and local cerebral glucose utilization during chemical stimulation of the nucleus tractus solitarii of anesthetized rats.

This study was conducted to determine whether the decrease in cerebral blood flow (CBF) observed during chemical stimulation of the nucleus tractus solitarius (NTS) can be explained by a decrease in cerebral metabolism. In anesthetized (urethane and chloralose), paralyzed and artificially ventilated rats, neurons in the NTS were chemically stimulated by microinjection of L-glutamate. Local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) were quantified in 43 brain structures by quantitative autoradiographic techniques using [14C]iodoantipyrine and 2-[14C]deoxyglucose, respectively. During chemical stimulation of the NTS (n = 6), LCBF decreased significantly in 32 of the 43 structures investigated when compared to either a control group with artificial cerebrospinal fluid injection (n = 6), or a controlled hemorrhage group (n = 5). In the controlled hemorrhage group, blood pressure was decreased to a degree comparable to that induced by microinjection of L-glutamate into the NTS. Mean blood flow of all structures investigated was significantly (P < 0.01) lower in the stimulation group than that in the control group and in the hemorrhage group. No significant differences in LCGU were observed between the three investigated groups in all structures examined except for an increase in LCGU in the chemically stimulated NTS site. It is concluded that the decrease in LCBF measured in most brain structures during chemical stimulation of the NTS is not caused by a decrease in LCGU in these structures and may therefore be explained by neurogenic influences on brain vessels.

Animals↗

PubMed1998

The involvement of matrix metalloproteinases and inflammation in lumbar disc herniation.

STUDY DESIGN: Surgically obtained herniated lumbar disc specimens were stained with hematoxylin-eosin or toluidine blue (for detection of proteoglycans) or were immunostained with monoclonal antibodies (CD68), antihuman interstitial collagenase (matrix metalloproteinase [MMP]-1) and antihuman stromelysin (MMP-3). OBJECTIVE: To investigate the possible correlation of matrix metalloproteinase activity to granulation tissue formation and lumbar disc herniation, depending on the type of herniation. SUMMARY OF BACKGROUND DATA: Interstitial collagenase and stromelysin have been implicated in the degradation of the matrix of articular cartilage in rheumatoid arthritis, osteoarthritis and degenerated disc tissues. However, their role in the herniation of the intervertebral disc has received little study. METHODS: Twenty-one specimens of lumbar disc herniation (classified as protrusions, subligamentous extrusions, transligamentous extrusions, and sequestrations) and four nonherniated discs were stained with hematoxylin-eosin or toluidine blue or were immunostained with monoclonal antibodies to CD20, CD45RO, and CD68, anti-MMP-1, and anti-MMP-3, using the avidin-biotin-peroxidase complex method. The amount of granulation tissue and results of staining were graded to examine differences in histology among the four herniation types. RESULTS: In sequestration and transligamentous extrusion specimens, granulation tissue containing many CD68-positive macrophages was commonly observed. Most cells in granulation tissue, as well as chondrocytes, stained positively with anti-MMP-1 and anti-MMP-3 antibodies. Granulation tissue was less commonly observed in subligamentous extrusions and was absent from most protrusion specimens and all nonherniated specimens. B and T lymphocytes could not be demonstrated in granulation tissue. CONCLUSIONS: The increased staining of MMP-1 and MMP-3 associated with inflammatory cells of granulation tissue in herniated discs suggests a causal correlation of these proteinases to tissue degradation in herniation.

Adolescent↗

PubMed1998

Symptomatic monostotic fibrous dysplasia of the thoracic spine.

STUDY DESIGN: A case report of monostotic fibrous dysplasia of the thoracic spine with symptoms of chest and back pain. OBJECTIVE: To treat this lesion with surgery. SUMMARY OF BACKGROUND DATA: Monostotic fibrous dysplasia of the thoracic spine is rarely seen. Few reports of this disorder appear in the literature. This is the fifth case of monostotic fibrous dysplasia of the thoracic spine presented to date. METHODS: The patient was a 48-year-old woman with monostotic fibrous dysplasia involving the thoracic spine of the 10th vertebral body and the 10th left rib. Surgical removal of the tumor was carried out. The defect was packed with hydroxyapatite graft material. Arthrodesis or internal fixation was not made. RESULTS: The diagnosis of fibrous dysplasia was made histologically. No obvious recurrence of the lesion has been seen for 3 years. CONCLUSION: Surgical removal of the tumor and transplantation of hydroxyapatite was effective treatment for the reported patient.

Bone Substitutes↗

PubMed1998

Pyk2 is a downstream mediator of the IL-2 receptor-coupled Jak signaling pathway.

Many cytokines transmit signals to the cell interior through activation of receptor-associated, Janus family protein tyrosine kinases (Jak PTKs). The interleukin-2 receptor (IL-2R) is associated with the Jak1 and Jak3 PTKs, and ligand-induced activation of these PTKs is essential for lymphocyte proliferation. Here, the nonreceptor PTK, Pyk2, was found to be activated following IL-2 stimulation in a Jak-dependent manner. Furthermore, physical association was detected between endogenous Pyk2 and Jak3, and a dominant interfering mutant of Pyk2 inhibited IL-2-induced cell proliferation without affecting Stat5 activation. Collectively, these results suggest that Pyk2 is a newly identified component of the Jak-mediated IL-2 signaling pathway.

Binding Sites↗

PubMed1998

Rho-kinase phosphorylates COOH-terminal threonines of ezrin/radixin/moesin (ERM) proteins and regulates their head-to-tail association.

The ezrin/radixin/moesin (ERM) proteins are involved in actin filament/plasma membrane interaction that is regulated by Rho. We examined whether ERM proteins are directly phosphorylated by Rho-associated kinase (Rho-kinase), a direct target of Rho. Recombinant full-length and COOH-terminal half radixin were incubated with constitutively active catalytic domain of Rho-kinase, and approximately 30 and approximately 100% of these molecules, respectively, were phosphorylated mainly at the COOH-terminal threonine (T564). Next, to detect Rho-kinase-dependent phosphorylation of ERM proteins in vivo, we raised a mAb that recognized the T564-phosphorylated radixin as well as ezrin and moesin phosphorylated at the corresponding threonine residue (T567 and T558, respectively). Immunoblotting of serum-starved Swiss 3T3 cells with this mAb revealed that after LPA stimulation ERM proteins were rapidly phosphorylated at T567 (ezrin), T564 (radixin), and T558 (moesin) in a Rho-dependent manner and then dephosphorylated within 2 min. Furthermore, the T564 phosphorylation of recombinant COOH-terminal half radixin did not affect its ability to bind to actin filaments in vitro but significantly suppressed its direct interaction with the NH2-terminal half of radixin. These observations indicate that the Rho-kinase-dependent phosphorylation interferes with the intramolecular and/ or intermolecular head-to-tail association of ERM proteins, which is an important mechanism of regulation of their activity as actin filament/plasma membrane cross-linkers.

3T3 Cells↗

PubMed1998

The upregulation of p27Kip1 by rapamycin results in G1 arrest in exponentially growing T-cell lines.

An immunosuppressant Rapamycin (Rap) has been reported to cause G1 arrest by inhibiting p70 S6 kinase and G1 cyclin/cdks kinase activities when added to quiescent cells with mitogens. However, antiproliferative effects of Rap on exponentially growing cells have been poorly investigated. We examined the intracellular events after the treatment of Rap in exponentially growing T cells and found that Rap upregulated a cdks inhibitor, p27Kip1 at both mRNA and protein levels in Rap-sensitive cells. Antiproliferative effect of Rap was mainly ascribed to the inhibition of cyclin E/cdk2 kinase activity through the formation of cyclin E/cdk2-p27Kip1 complex rather than inhibition of p70 S6 kinase activity. Furthermore, we showed that Rap-sensitive cells with elevated p27Kip1 expression lost sensitivity to Rap when antisense p27Kip1 was introduced, which indicates that the basal level of p27Kip1 is one of the limiting factors that determine the sensitivity to Rap in already cycling cells. These data suggest the presence of a putative threshold level of p27Kip1 at late G1 phase in already cycling cells. Rap may cause G1 arrest by upregulating the amount of p27Kip1 beyond the threshold in some Rap-sensitive cells that are exponentially growing.

CDC2-CDC28 Kinases↗