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Biomedical subjects

R Kaneko

Publications and source records attributed to R Kaneko.

At least 19 recordsLinked to original sources
PubMed2007

CD30+ large cell transformation of mycosis fungoides after psoralen plus ultraviolet A photochemotherapy.

Psoralen plus ultraviolet A (PUVA) photochemotherapy is widely used for the therapy of mycosis fungoides (MF). Clinical progression of MF is often associated with an increase in the size of tumour cells known as transformation. We report two patients with CD30+ large cell transformation that appeared after low-dose PUVA therapy for MF. Clinical data, histopathology, immunohistopathology and T-cell receptor gene rearrangement were studied. Nodules consisted of atypical large cells that expressed CD30. Monoclonal rearrangement of T-cell receptors was observed in one case. Low-dose PUVA therapy may be associated with CD30+ large cell transformation in patients with MF.

Aged↗
PubMed2004

Idiopathic acquired generalized anhidrosis due to occlusion of proximal coiled ducts.

Idiopathic acquired generalized anhidrosis is a very rare disease of unknown pathogenesis. We report a 25-year-old man with acquired generalized anhidrosis due to occlusion of the coiled ducts. He did not have sweat secretion over the entire surface of the body, including the palms and soles. Sweat-inducing stimuli provoked tingling pain on the skin. Pilocarpine iontophoresis on the forearm did not induce sweat secretion. Neurological examination did not reveal any abnormality in the central or peripheral nervous system. Skin biopsy showed that the coiled ducts were occluded by an amorphous eosinophilic substance. This amorphous eosinophilic substance was positive with periodic acid-Schiff (PAS) staining and was resistant to digestion by diastase. Electron microscopy demonstrated that the coiled ducts were completely occluded by an amorphous substance. The substance occluding the coiled ducts contained fibrous structures. These findings suggested that the acquired generalized anhidrosis in this patient was caused by occlusion of the coiled ducts by a PAS-positive substance probably derived from dark cell granules.

Adult↗
PubMed2001

An enzymatic cycling method for the measurement of myo-inositol in biological samples.

INTRODUCTION: A sensitive and simple enzymatic cycling method is described for the quantitation of myo-inositol in biological samples. METHODS: The method involves the use of a sensitive and simple enzymatic cycling method is described for the quantitation of myo-inositol in biological samples. The method involves use of thio-NAD(+), NADH and thermostable myo-inositol dehydrogenase (IDH; EC. 1.1.1.18) and measurement of the increase in absorbance at 405 nm of thio-NADH at 37 degrees C. RESULTS: The calibration curve for myo-inositol was linear (r=1.00) between 10 and 400 micromol/l. Analytical recoveries of exogenous myo-inositol added to serum and urine were 100-105% and 98-103%, respectively. Within-run and between-run coefficient of variation (CV) were 0.6-2.1% and 1.1-3.0%, respectively. This method was free from interference by hemoglobin, bilirubin, ascorbate, chyle, various sugars, sugar alcohol and myo-inositol phosphates. With the use of myo-inositol as a standard solution, the serum myo-inositol concentration (mean+/-SD) was significantly greater in patients with diabetes mellitus (DM) without nephropathy (73.0+/-13.8 micromol/l, n=7) than in healthy individuals without DM (61.0+/-12.4 micromol/l, n=20). The urinary myo-inositol concentration was also significantly greater in patients with DM without nephropathy (793.3+/-870.3 micromol/l, n=7) than in healthy individuals without DM (76.0+/-63.0 micromol/l, n=13). CONCLUSIONS: This new method is simple, sensitive and enables quantitative analysis of myo-inositol.

Aged↗
PubMed2001

Curative treatment of central hemangioma in the mandible by direct puncture and embolisation with n-butyl-cyanoacrylate (NBCA).

Management of central hemangioma in the mandible is difficult because of the abundant vascular network in this region. One of the most common signs of these patients, especially in the mixed dentition period, is hypermobility of the teeth with spontaneous hemorrhage from the surrounding gingival sulcus. Various therapeutic modalities have been considered, but surgery is the most frequently used. In cases of a large extensive lesion, however, intralesional injections of sclerosing agents have often been successful. A case of central hemangioma of the mandible with arteriovenous malformations in a 10-year-old girl is reported. She was treated with direct injection of an embolic material, n-butyl-cyanoacrylate, which brought satisfactory results. Preoperative embolisation of feeder vessels with Gelfoam and Avitene soaked in thrombin together with this direct injection is a safe treatment modality that is as effective as surgery.

Child↗
PubMed2001

Terminal deoxynucleotidyltransferase directly interacts with a novel nuclear protein that is homologous to p65.

BACKGROUND: Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase that enhances Ig and TcR gene diversity in the N region in B- and T-cells. TdT is found as a member of a large protein complex in the lysate of the thymocytes. To elucidate the molecular mechanism of the synthesis of the N region, we first attempted to isolate the genes with products that are interacting directly with TdT. RESULTS: Using a yeast two-hybrid system, we isolated a cDNA clone encoding a novel nuclear protein that interacts with TdT. This protein was designated as TdT interacting factor 1 (TdIF1). TdIF1 has a high degree of homology to the transcription factor p65, which belongs to the nuclear receptor superfamily. TdIF1 contains HMG-I and HMG-Y DNA binding domains (AT-hooks) and can bind to single- and double-stranded DNA. TdT and TdIF1 were co-eluted at position 232 kDa by gel filtration of MOLT4 lysate. TdIF1 can enhance TdT activity fourfold in vitro assay system using oligo(dT)16 as primers. CONCLUSIONS: TdIF1 binds directly to TdT, both in vitro and in vivo. TdIF1 and TdT exist as the members of a 232 kDa protein complex. TdIF1 can enhance TdT activity maximum fourfold in vitro assay system, suggesting that it positively regulates the synthesis of the N region during V(D)J recombination in the Ig and TcR genes.

Amino Acid Sequence↗
PubMed2001

Terminal deoxynucleotidyltransferase is negatively regulated by direct interaction with proliferating cell nuclear antigen.

BACKGROUND: The repertoires of Ig and TcR are generated by a combinatorial rearrangement of variable (V), diversity (D), and joining (J) segments (V(D)J recombination) in B- and T-cells. Terminal deoxynucleotidyltransferase (TdT) adds extra nucleotides (N nucleotides) at the junctions of the gene segments to enhance the Ig and TcR genes diversity. Using an anti-TdT antibody column, TdT has been purified as a member of a megadalton protein complex from rat thymus. The N region would be synthesized with the large protein complex. RESULTS: The cDNAs for proliferating cell nuclear antigen (PCNA) were isolated by yeast two-hybrid screening as the gene products which directly interacted with TdT. The interaction between PCNA and TdT was confirmed by co-immunoprecipitation, both in vitro and in vivo. TdT binds directly to a PCNA trimer, as shown by gel filtration. TdT interacts with PCNA in its DNA polymerization domain (DPD), but not in its BRCA-1 C-terminal (BRCT) domain. TdT activity was reduced to 17% of the maximum value by TdT/PCNA complex formation. CONCLUSION: TdT interacts directly with PCNA through its DPD. A functional consequence of this interaction is the negative regulation of TdT activity. These findings suggest that TdT catalyses the addition of N nucleotides under the negative control of PCNA during V(D)J recombination.

Binding Sites↗
PubMed2001

Structure-sweetness relationship in thaumatin: importance of lysine residues.

To clarify the structural basis for the sweetness of thaumatin I, lysine-modified derivatives and carboxyl-group-modified derivatives were prepared by chemical modification followed by chromatographic purification. The sweetness of derivatives was evaluated by sensory analysis. Phosphopyridoxylation of lysine residues Lys78, Lys97, Lys106, Lys137 and Lys187 markedly reduced sweetness. The intensity of sweetness was returned to that of native thaumatin by dephosphorylation of these phosphopyridoxylated lysine residues except Lys106. Pyridoxamine modification of the carboxyl group of Asp21, Glu42, Asp60, Asp129 or Ala207 (C-terminal) did not markedly change sweetness. Analysis by far-UV circular dichroism spectroscopy indicated that the secondary structure of all derivatives remained unchanged, suggesting that the loss of sweetness was not a result of major disruption in protein structure. The five lysine residues, modification of which affected sweetness, are separate and spread over a broad surface region on one side of the thaumatin I molecule. These lysine residues exist in thaumatin, but not in non-sweet thaumatin-like proteins, suggesting that these lysine residues are required for sweetness. These lysine residues may play an important role in sweetness through a multipoint interaction with a putative thaumatin receptor.

Adult↗
PubMed2001

Sweetness of sweet protein thaumatin is more thermoresistant under acid conditions than under neutral or alkaline conditions.

Thermostability of thaumatin and mechanisms of thermoinactivation were examined at 80 degrees C in the pH range from 2 to 10. The sweetness of thaumatin disappeared on heating at pH above 7 for 15 min, but the sweetness remained even after heating at 80 degrees C for 4 h at pH 2. This indicated that the sweet protein thaumatin is more thermoresistant under acid conditions than under neutral or alkaline conditions. Prolonged heating of thaumatin under acid conditions slowly reduced sweetness, and produced a heterogeneous population of molecules, all of which was soluble and monomeric. The resultant molecules were clearly distinct from those generated by heating at pH above 7. Hydrolysis of peptide bonds and other irreversible chemical reactions slowly took place in the molecule heated under acid conditions, and it would be, in part, a cause of thermoinactivation of thaumatin under acid conditions. The thermostability of thaumatin and the mechanism of thermoinactivation were largely dependent on pH.

Drug Stability↗
PubMed2000

Tandem mass spectrometric analysis of (13)C-containing ions from a mixture of homologous peptides differing by one mass unit at a residue.

Tandem mass spectrometry of a mixture of two peptides that differ from each other by a single mass unit due to mutation is presented. The mutant beta-globin of hemoglobin Hoshida is present along with the normal counterpart, and the amino acid substitution of glutamine for glutamic acid is located within tryptic peptide T5 of M(r) 2057. 9. The mass of the mutated peptide is 1 u lower. In the isotopic cluster for the doubly charged ion of the peptide T5, the resolved ion with mass of 1030.0 represents the normal peptide with 93 (12)C atoms and the mutated one with 92 (12)C and one (13)C atoms. Collision-induced dissociation (CID) of this composite ion identified the mutation by presenting a key fragment derived from the (12)C-only mutant peptide, as reported in a previous study. Similarly, when an ion containing multiple (13)C atoms was selected as a precursor for CID, the mutation could be identified, even in large fragments, by a marked change in the shape of the isotopic cluster for the consecutive product ions. This study demonstrates the merit of selecting a resolved ion rather than the whole isotopic cluster as a precursor in the CID measurements of large peptides or proteins for characterizing heterozygous mutations.

Amino Acid Sequence↗
PubMed2000

Site-directed mutagenesis in hemoglobin: test of functional homology of the F9 amino acid residues of hemoglobin alpha and beta chains.

The cysteine residue at F9(93) of the human hemoglobin (Hb A) beta chain, conserved in mammalian and avian hemoglobins, is located near the functionally important alpha1-beta2 interface and C-terminal region of the beta chain and is reactive to sulfhydryl reagents. The functional roles of this residue are still unclear, although regulation of local blood flow through allosteric S-nitrosylation of this residue is proposed. To clarify the role of this residue and its functional homology to F9(88) of the alpha chain, we measured oxygen equilibrium curves, UV-region derivative spectra, Soret-band absorption spectra, the number of titratable -SH groups with p-mercuribenzoate and the rate of reaction of these groups with 4, 4'-dipyridine disulfide for three recombinant mutant Hbs with single amino acid substitutions: Ala-->Cys at 88alpha (rHb A88alphaC), Cys-->Ala at 93beta (rHb C93betaA) and Cys-->Thr at 93beta (rHb C93betaT). These Hbs showed increased oxygen affinities and impaired allosteric effects. The spectral data indicated that the R to T transition upon deoxygenation was partially restricted in these Hbs. The number of titratable -SH groups of liganded form was 3.2-3.5 for rHb A88alphaC compared with 2.2 for Hb A, whereas those for rHb C93betaA and rHb C93betaT were negligibly small. The reduction of rate of reaction with 4,4'-dipyridine disulfide upon deoxygenation in rHb A88alphaC was smaller than that in Hb A. Our experimental data have shown that the residues at 88alpha and 93beta have definite roles but they have no functional homology. Structure-function relationships in our mutant Hbs are discussed.

Allosteric Regulation↗
PubMed1999

Establishment of a combined strategy of genetic and mass spectrometric analyses for characterizing hemoglobin mutations. An example of Hb Hoshida (beta43Glu-->Gln).

Structural analysis of mutant hemoglobins has been efficiently accomplished by a consecutive mass spectrometric strategy: molecular mass measurement of the protein to detect mutation and to determine the molecular mass change, and fragmentation analysis with collision-induced dissociation to determine the site and type of mutation. A flaw of this method is an inherent inability to detect a mutation associated with no or little change of the molecular mass. In the present study, the strategy was improved by incorporating genetic analysis prior to mass spectrometry, which confirms the resulting amino acid change and searches for possible post-translational modifications. The method was applied to an unknown mutant, and elucidated a substitution of glutamine for glutamic acid at position 43 of beta-globin subunit, the mutation of Hb Hoshida.

Amino Acid Sequence↗
PubMed1999

Conformational fluctuation of native-like and molten-globule-like cytochrome c observed by time-resolved hole burning.

Nanosecond to millisecond conformational fluctuations of Zn-substituted cytochrome c (ZnCytc) have been studied by the time-resolved transient hole-burning method. The investigation of low-temperature dynamics has been made on the ZnCytc solution sample in a water-glycerol mixture. The conformational fluctuations in the native-like and the molten-globule (MG)-like states have been compared for the aqueous solution samples at room temperature. ZnCytc in the MG-like state has been prepared by adding 200 mM NaClO4 to the protein solution with a pH of 2.1, and the formation of the MG-like state has been confirmed by both the far-UV CD and the visible absorption spectra. The hole spectrum of ZnCytc has been found to consist of two nearly degenerate components, that is, the Qx and Qy bands. The temporal change in the Qx component hole spectrum has been extracted by fitting the observed hole spectrum to the three-Gaussian form. The experimental results for ZnCytc dissolved in a water-glycerol mixture have revealed that the conformational fluctuation of ZnCytc is suppressed around 200 K, which is nearly the same temperature as the glass-like transition point of Zn-substituted myoglobin (ZnMb) and also as the glass-transition point of the solvent. This supports the idea of the solvent-induced glass-like transition of a protein. It has been also found that at physiological temperatures the time scale of the conformational fluctuation of ZnCytc lies around a few tens of nanoseconds, which is 2-3 orders of magnitude faster than that of ZnMb. The experimental results for the aqueous solution samples have shown that the difference between the native-like and the MG-like states is not conspicuous. However, they are indicative of the appearance of the slower conformational fluctuation in the MG-like state.

Animals↗
PubMed1999

Analysis of Th1 and Th2 cytokine production by peripheral blood mononuclear cells as a parameter of immunological dysfunction in advanced cancer patients.

PURPOSE: The presence of immunological dysfunction has not been well demonstrated in cancer patients. Recent studies have revealed that the immune response can be classified into types 1 and 2, and in the present work the immunological function of patients was studied from the perspective of these two types of response. METHODS: Types 1 and 2 immune response were evaluated by monitoring the production of various cytokines by peripheral blood mononuclear cells from 38 patients with advanced cancer of various organs and 20 healthy subjects. The usual immunological parameters, differential cell leukocyte counts, the level of T cell subsets (CD4 and CD8) and natural killer activity were also examined. RESULTS: The production of interleukin-2 (IL-2), interferon gamma, IL-10, IL-12 and tumor necrosis factor alpha was found to be significantly lower in the patients (75 +/- 57, 171 +/- 205, 40 +/- 34, 8 +/- 8, 1450 +/- 1010 pg/ml) than in healthy subjects (143 +/- 99, 422 +/- 296, 64 +/- 34, 16 +/- 10, 2550 +/- 950 pg/ml); however, the mean level of IL-4 in the patients seemed to be higher. The correlations between different cytokine levels suggested that they were produced differently. Lymphocyte counts were significantly lower in patients, but there was no difference in the other usual immunological parameters. CONCLUSIONS: Patients with advanced cancer are deficient in monocytes and the type 1 immune response. The measurement of various cytokines reported in this study provides a more sensitive and valuable tool for evaluating the function of cell-mediated immunity in cancer patients than do the usual tests.

Adult↗