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Biomedical subjects

M Kato

Publications and source records attributed to M Kato.

At least 577 records · Page 32Linked to original sources
PubMed1999

[Outpatient chemotherapy with infusional 5-fluorouracil in advanced gastrointestinal cancer].

These studies were designed to evaluate the efficacy, toxicity, and resulting quality of life (QOL) of outpatient chemotherapy with infusional 5-FU for advanced gastrointestinal cancer. Schedule, sch. A: Treatment consisted of CI 5-FU 200 mg/m2/day, days 1-28, IVB Leucovorin 20 mg/m2 q week. Fifteen patients with advanced gastrointestinal cancer were treated to maintain the efficacy of prior inpatient chemotherapy. Twenty-one patients treated with adjuvant chemotherapy were added to evaluate toxicity and QOL. The mean time to progression (TTP) was 2.6 months. Grade 2 toxicities were seen, including mucositis (23%) and diarrhea (7%). Hand-foot syndrome was seen 60% of patients. The mean QOL score was 89.5 +/- 7.8. Sch.B: Treatment consisted of weekly 24 h infusion of 5-FU 2,600 mg/m2. 5-FU was administered using a Groshong catheter and Baxter infusor LV5 (5 ml/hr). Nine patients with advanced gastrointestinal cancer were treated. Twenty-one patients were treated with adjuvant chemotherapy. The mean TTP was 3.6 month. Grade 2 toxicities were seen, including leucocytopenia (7%), mucositis (3%), diarrhea (10%), and nausea and vomiting (10%). The mean QOL score was 82.6 +/- 10.7. In conclusion, both 5-FU schedules are feasible for outpatient chemotherapy for advanced gastrointestinal cancer.

Ambulatory Care↗
PubMed1999

High level production of thermostable alpha-amylase from Sulfolobus solfataricus in high-cell density culture of the food yeast Candida utilis.

The alpha-amylase from Sulfolobus solfataricus has the commercially important ability to hydrolyze glycosyltrehalose and can be used for the production of trehalose from soluble starch. We have produced this enzyme in the food yeast Candida utilis at extremely high levels. Because the S. solfataricus gene was previously shown to be very poorly expressed, the gene was resynthesized based on codons preferentially found in the highly expressed C. utilis glyceraldehyde-3-phosphate dehydrogenase (GAP) gene. Expression of this synthetic gene under the control of the GAP promoter yielded biologically active alpha-amylase, accounting for more than 50% of the soluble protein. Comparison of the expression levels of various chimeric constructs of the synthetic and native genes indicated that the production level of the alpha-amylase was improved more than 2x10(4)-fold by substituting the native gene with the synthesized one. Northern analysis revealed the formation of short mRNAs in transformants with constructs containing native gene fragments, suggesting that premature termination of the transcripts is responsible for the low production level. The alpha-amylase-producing C. utilis cells were grown up to 92 grams dry cell weight per liter in a synthetic medium, yielding 12.3 g/l alpha-amylase which accounts for up to 27% of total cell proteins.

Amino Acid Sequence↗
PubMed1998

Four novel mutations of the connexin 32 gene in four Japanese families with Charcot-Marie-Tooth disease type 1.

DNA-based mutation analysis on the connexin 32 gene was performed in 49 families with Charcot-Marie-Tooth disease (CMT) type 1 but without duplication involving the chromosomal region, 17p12-p11.2. Mutations were identified in five of the 49 families, and four of the five mutations were hitherto undescribed: Va137Met, Glu57His, Arg142Glu, Val177Ala. X-linked CMT sometimes lacks evidence for X-linked transmission and cannot be differentiated from CMT type 2, especially in females with mildly decreased nerve conduction velocity. Therefore, molecular analysis is useful for molecular pathology of their disease.

Adolescent↗
PubMed1998

Novel mutations of the glutaryl-CoA dehydrogenase gene in two Japanese patients with glutaric aciduria type I.

We identified three different point mutations in the glutaryl-CoA dehydrogenase (GCDH) gene in two unrelated Japanese patients with glutaric aciduria type I (GA-I). One patient was a homozygote for Arg355His and the other a compound heterozygote for Ser305Leu and Met339Val. Arg355His and Met339Val are mutations hitherto undescribed, and all three mutations are predicted to alter the secondary structure of GCDH. Molecular analysis is useful for definite diagnosis and/or prenatal diagnosis of GA-I.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

Cloning of a thermostable ascorbate oxidase gene from Acremonium sp. HI-25 and modification of the azide sensitivity of the enzyme by site-directed mutagenesis.

A gene encoding a thermostable ascorbate oxidase (ASOM) was cloned from Acremonium sp. HI-25 and sequenced. The gene comprised 1709 bp and was interrupted by a single intron of 57 bp. ASOM consisted of 551 amino acids including a signal peptide with a molecular mass of 61200, and contained four histidine-rich regions with high sequence homology to the corresponding regions of other multicopper oxidases. The ASOM gene was expressed in Aspergillus nidulans under the Aspergillus oryzae Taka-amylase A gene promoter. The recombinant enzyme (An-ASOM) exhibited almost the same enzymatic properties as ASOM. The ASOM gene was mutated by site-directed mutagenesis with reference to the amino acid sequences of plant enzymes to generate enzymes with altered azide sensitivity. Site-directed mutagenesis at the trinuclear active copper site resulted in an increase in azide resistance; the Ala465Leu and Phe463Trp/Ala465Leu mutants exhibited approximately 10 and 20% increases in azide resistance, respectively.

Acremonium↗
PubMed1998

Outcomes of stent-graft treatment of false lumen in aortic dissection.

BACKGROUND: Stent-graft treatment for aortic disease promises to lead to a less invasive therapy than conventional surgical therapy. However, this treatment has not been established as a therapy for aortic dissection. The aim of this study was to examine the effect of stent-graft treatment of aortic dissection, as measured by follow-up data on entry site closure, clotting in the false lumen, and the outcome of the false lumen from the acute to chronic phase after operation. METHODS AND RESULTS: We used a stent-graft of our own design to close the entry site of aortic dissection in 21 cases: 9 were acute (< 14 days), 8 subacute (< 6 months), and 4 chronic (> 6 months). Nine were type A and 12 were type B. In 15 cases, the stent-graft was inserted through the transverse arch, which had been surgically opened under median sternotomy. In the other 6 cases, the stent-graft was inserted by means of a transcatheter through a femoral artery. Using computed tomographic scans, we followed and examined clot formation in the false lumen and reduction in size of the false lumen at 3 levels: at the level of maximum aortic diameter, at the distal end of the stent-graft, and 50 mm distal to the stent-graft. The entry sites were successfully closed in 19 cases (90.4%); in the remaining 2 (both treated with a transcatheter) there was perigraft leakage into the false lumen. The hospital mortality rate of these stent-graft treatments was 14.3% (3 of 21). At 2 weeks after operation, the false lumen had completely clotted, respectively, in 100%, 77%, and 38% of cases at the 3 measurement levels. Substantial shrinkage (> 50% in diameter) of the false lumen at 6 months after the operation was observed in 72%, 60%, and 38% of cases at the respective levels. Shrinkage of the false lumen was particularly enhanced in patients treated within 6 months from the onset of dissection: The false lumen shrank by > 50% in 93%, 75%, and 50% of patients. CONCLUSIONS: In cases of aortic dissection, the stent-graft is an effective tool for closing the entry site and promoting clot formation in the false lumen and for reducing the size of the false lumen within 6 months of the onset of dissection if the entry site has been closed.

Adult↗
PubMed1998

Distribution, morphology, and gamma-aminobutyric acid immunoreactivity of horizontally projecting neurons in the macaque inferior temporal cortex.

In area TE of the macaque inferior temporal cortex, horizontal axons running parallel to the pial surface mediate interactions between laterally displaced sites across the cortex. We examined the spatial distribution and the types of cells that give rise to these horizontal axons, which are important factors in determining the nature of the lateral interactions in TE. Intracortical injections of retrograde tracers labeled columnar clusters of cells and cells diffusely scattered within TE. The clusters were 0.35 +/- 0.11 mm (mean +/- SD) in diameter and were laterally distributed up to 6 mm from the injection site. Labeled cells were found in layers 2 to 6, with only a few labeled cells seen in layer 4. The clustering of labeled cells in layers 5 and 6 was looser than that in layers 2 and 3. Intracellular staining of the retrogradely labeled cells revealed that the majority of them were typical or modified pyramidal cells, both within and between the clusters. Only a few nonpyramidal interneurons were also stained at the fringe of the tracer injection site. Consistent with these results, only a small proportion of the retrogradely labeled cells exhibited gamma-aminobutyric acid (GABA)-like immunoreactivity, mostly found within 1 mm from the injection site. The results indicate that direct horizontal interactions in TE are predominantly mediated by pyramidal or modified pyramidal cells in layers 2, 3, 5, and 6 and are primarily excitatory in nature. The contribution of GABAergic interneurons to direct horizontal interactions is restricted to only short-distance projections.

Animals↗
PubMed1998

The effect of methamphetamine on the release of acetylcholine in the rat striatum.

We examined the effect of methamphetamine on the release of acetylcholine in the striatum of freely moving rats, using an in vivo microdialysis method. The basal level of acetylcholine was 3.67+/-0.47 pmol/30 microl per 15 min in the presence of neostigmine (10 microM). Tetrodotoxin (1 microM), a selective blocker of voltage-dependent Na+ channels, markedly inhibited the release of acetylcholine in the striatal perfusates. Apomorphine (1.0 mg/kg, i.p.), a dopamine receptor agonist, also significantly attenuated acetylcholine release. Methamphetamine (0.1 and 0.5 mg/kg, i.p.) did not immediately affect acetylcholine release in the striatum, but a dose of 1.0 mg/kg (i.p.) induced an increase of acetylcholine release in the striatum at 15-60 min. Striatal infusion of methamphetamine (5 and 10 microM) did not influence acetylcholine release. The increase following intraperitoneal administration of methamphetamine was slightly diminished by haloperidol (0.5 mg/kg). After microinjection of the neurotoxin, 6-hydroxydopamine (6 microg/3 microl), in the substantia nigra 7 days before, the increase of acetylcholine induced by the administration of methamphetamine (1.0 mg/kg) was slightly attenuated, whereas the administration of reserpine (2 mg/kg, i.p.) 24 h before, combined with alpha-methyl-p-tyrosine (300 mg/kg, i.p.) 2.5 h before, completely blocked the increase in release of acetylcholine. These findings suggest that methamphetamine exerts an excitatory influence on striatal acetylcholine release in freely moving rats, and that this excitatory effect involves the dopaminergic system and the catecholaminergic system.

Acetylcholine↗
PubMed1998

Level of HgCl2-mediated phosphorylation of intracellular proteins determines death of thymic T-lymphocytes with or without DNA fragmentation.

Exposure to Hg2+ at a wide range of concentrations (approximately 1-100 microM) more or less caused the death of murine thymic T-lymphocytes, and exposure to 1 microM but not 10 microM (or more) of Hg2- induced DNA fragmentation. Exposure of cells to Hg2+ caused phosphorylation of multiple cellular proteins at the tyrosine residue in a concentration-dependent manner. We found that not only the DNA fragmentation induced by 1 microM Hg2+ but also the cell death bypassing DNA fragmentation caused by 10 microM or more Hg2+ was partly inhibited by protein kinase inhibitors such as staurosporine and herbimycin A. This result suggested the involvement of a protein phosphorylation-linked signal in the mechanism of the Hg2+-mediated cell death with or without DNA fragmentation. Analysis of proteins by both one- and two-dimensional electrophoresis and immunoblot showed that a 52-kDa Shc protein was heavily phosphorylated by an early signal delivered by a high concentration of Hg2+, which also phosphorylated extracellular signal-regulated kinase 1 (ERK1; p44) and ERK2 (p42) of the mitogen-activated protein kinase (MAPK) family in a concentration- and time-dependent manner. The c-Jun amino terminal kinase (p54), which is a distant relative of the MAPK family, was also phosphorylated by the treatment with Hg2+. This eventually formed the signaling cascade that ended with a nuclear target by phosphorylating c-jun at the serine 73. This phosphorylation of c-jun was inhibited by staurosporine. These results suggest that a high level of Hg2+-mediated protein phosphorylation-linked signal induces rapid cell death bypassing DNA fragmentation, whereas a lower level induces cell death accompanying DNA fragmentation. This conclusion in turn implies that DNA fragmentation is not always a prerequisite for the signal transduction-dependent cell death of T-lymphocytes.

Animals↗
PubMed1998

Evidence for the presence of multiple forms of Sph kinase in human platelets.

The intracellular distribution of sphingosine (Sph) kinase activity was examined in human platelets. A large proportion (72%) of the total activity was found to be associated with the membrane fraction, and the membrane-associated fraction had higher specific activity compared with the cytosolic enzyme. Most of the membrane-associated activity could be extracted with 1 M NaCl. The cytosolic activity was unstable upon heat treatment, with 80% of the activity being lost during incubation at 45 degreesC for 1 h, whereas the NaCl-extractable fraction was stable under the same conditions. When subjected to Mono Q column chromatography, the cytosolic fraction produced two activity peaks and the NaCl-extractable fraction gave a single peak. These three Sph kinase activities showed different responses to stimulation by beta-octylglucoside and inhibition by N, N-dimethylsphingosine and l-threo-dihydrosphingosine, suggesting the presence of multiple enzyme forms in human platelets.

Blood Platelets↗
PubMed1998

Premature bifurcation of the apical dendritic trunk of vibrissa-responding pyramidal neurones of X-irradiated rat neocortex.

1. Electrophysiological and morphological experiments were performed on the pyramidal neurones of the somatosensory neocortex of the adult rat that had been exposed in utero to 200 rad of X-irradiation. Under urethane anaesthesia, evoked gross potentials, extracellular and intracellular neuronal responses, and laminar field potentials were recorded. The evoked epicortical potential to deflection of a single whisker was a long-lasting positive wave which contrasted with a biphasic positive-negative complex in unirradiated controls. Neurones were initially tested during extracellular recording for responses to whisker deflections. This was followed by intracellular injection with horseradish peroxidase (HRP), and the HRP-stained neuronal elements were visualized using diaminobenzidine as a chromagen. 2. Fifty neurones were recorded and stained through the soma. The mean response latency was 15.1 ms. Of these, thirty-six showed premature bifurcation of the apical dendrite. The angle of bifurcation of the apical dendrite was measured in the coronal plane and was found to be a function of the depth at which the soma was located and the distance between the soma and bifurcation point. It was suggested that the apical dendrites of these neurones underwent premature bifurcation due to an imbalance between the growth of neurones and skull. 3. Fifteen neurones were recorded and stained through the presumed apical dendritic shaft. The mean response latency was 19.5 ms. The electrode track left in the histological specimen pointed to the stained apical dendrite. Dendritic elements distal to the entry point were preferentially filled with HRP. In no cases were somata stained. There was, in turn, no evidence of recording from dendritic elements distal to the bifurcation since no electrode track was found to point to these elements. That dendritic spike responses may not travel beyond the bifurcation was further substantiated by laminar analysis of field potentials.

Algorithms↗
PubMed1998

In vivo effects of pioglitazone on uncoupling protein-2 and -3 mRNA levels in skeletal muscle of hyperglycemic KK mice.

Pioglitazone is a thiazolidinedione drug (TZD) which potently and specifically stimulates peroxisome proliferator-activated receptor gamma (PPAR gamma) and sensitizes cells to insulin. Since TZDs are thought to increase energy expenditure, changes in mitochondrial thermogenesis uncoupling protein-2 and -3 mRNA levels in response to pioglitazone treatment were measured in mouse skeletal muscle. Normally hyperglycemic and hyperinsulinemic KK/Ta mice were given pioglitazone for 2 weeks to treat this non-insulin dependent diabetes-like condition. During treatment, UCP2 mRNA levels increased to 185% of normal untreated control levels in soleus muscle. In contrast, UCP3 mRNA levels significantly decreased, up to 67% of normal untreated control levels. Interestingly, UCP3 mRNA levels correlated quite strongly with blood glucose levels, with r = 0.82 for gastrocnemius tissue and r = 0.92 for soleus tissue. These results may indicate that pioglitazone increases glucose catabolism by direct upregulation of muscle UCP2 gene expression in vivo. Therefore, UCP3 gene expression is controlled by a different mechanism than UCP2 expression.

Animals↗
PubMed1998

Transgenic mouse model for skin malignant melanoma.

We report here on a novel metallothionein-I (MT)/ret transgenic mouse line in which skin melanosis, benign melanocytic tumor and malignant melanoma metastasizing to distant organs develop stepwise. The process of tumor development and its malignant transformation in this line may resemble that of the human giant congenital melanocytic nevus that is present at birth and that frequently gives rise to malignant melanoma during aging. We observed an increase in the expression level and activity of the ret transgene during the disease progression. That increase in transgene expression accompanied an activation of mitogen-activated protein kinases (MAPKs) and c-Jun as well as matrix metalloproteinases. These results suggest that progressive dysregulation of the expression level of the ret transgene might play a crucial role in the malignant transformation of melanocytic tumors developed in the MT/ret transgenic mouse line.

Animals↗
PubMed1998

High-pressure solution X-ray scattering of protein using a hydrostatic cell with diamond windows.

A hydrostatic high-pressure cell (maximum pressure 700 MPa) with synthetic diamond windows is applied to measure small-angle X-ray scattering of a protein at high pressure. Use of the present cell allows an accurate solvent background correction, providing quantitative analyses. The performance of the present cell for X-ray scattering is shown by using lysozyme as a sample solution. From the Guinier plot, values of the radius of gyration of lysozyme are evaluated to be 15.31 +/- 0.09 A at 1 atm (0.10 MPa) and 14.80 +/- 0.15 A at 400 MPa.

Journal Article↗