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T Konno

Publications and source records attributed to T Konno.

At least 19 recordsLinked to original sources
PubMed2000

A partially unfolded structure of the alkaline-denatured state of pepsin and its implication for stability of the zymogen-derived protein.

Pepsin, a gastric aspartic proteinase, is a zymogen-derived protein that undergoes irreversible alkaline denaturation at pH 6-7. Detailed knowledge of the structure of the alkaline-denatured state is an important step in understanding the mechanism of the formation of the active enzyme. An extensive analysis of the denatured state at pH 8.0 was performed using a variety of techniques including (1)H nuclear magnetic resonance spectroscopy and solution X-ray scattering. This analysis indicates that the denatured state under these conditions has a compact and globular conformation with a substantial amount of secondary and tertiary structures. The data suggest that this partially structured species has a highly folded region and a flexible region. The NMR measurements suggest that the folded region contains His53 and is located at least partly in the N-terminal lobe of the protein. The alkaline-denatured state experiences a further reversible denaturation step at higher pH or on heating; the midpoints of the unfolding transition are pH 11.5 (at 25 degrees C) and 53.1 degrees C (at pH 8.0), respectively. The present findings suggest that the proteolytic processing of pepsinogen has substantially modified the ability of the protein to fold, such that its folding process cannot progress beyond the partially folded intermediate of pepsin.

Alkylating Agents↗
PubMed2000

Novel interaction of the voltage-dependent sodium channel (VDSC) with calmodulin: does VDSC acquire calmodulin-mediated Ca2+-sensitivity?

The voltage-dependent sodium channel (VDSC) interacts with intracellular molecules to modulate channel properties and localizations in neuronal cells. To study protein interactions, we applied yeast two-hybrid screening to the cytoplasmic C-terminal domain of the main pore-forming alpha-subunit. We found a novel interaction between the C-terminal domain and calmodulin (CaM). By two-hybrid interaction assays, we specified the interaction site of VDSC in a C-terminal region, which is composed of 38 amino acid residues and contains both IQ-like and Baa motifs. Using a fusion protein of the C-terminal domain, we showed that interaction with CaM occurred in the presence and absence of Ca(2+). Two synthetic peptides, each covering the IQ-like (NaIQ) or the Baa motifs (NaBaa), were used to examine the binding property by a gel mobility shift assay. Although the NaIQ and NaBaa sequences are overlapped, NaBaa binds only to Ca(2+)-bound Ca(2+)CaM, whereas NaIQ binds to both Ca(2+)CaM and Ca(2+)-free apoCaM. Fluorescence spectroscopy of dansylated CaM showed Ca(2+)-dependent spectral changes not only for NaBaa.CaM but also for NaIQ.CaM. The results, taken together with other results, indicate that whereas the NaBaa.CaM complex is formed in a Ca(2+)-dependent manner, the NaIQ.CaM complex has two conformational states, distinct with respect to the peptide binding site and the CaM conformation, depending on the Ca(2+) concentration. These observations suggest the possibility that VDSC is functionally modulated through the direct CaM interaction and the Ca(2+)-dependent conformational transition of the complex.

Amino Acid Sequence↗
PubMed2000

Columnar epidermal necrosis: a unique manifestation of transfusion-associated cutaneous graft-vs-host disease.

BACKGROUND: In 1978, the first case of columnar epidermal necrosis was reported in a 6-year-old boy. There were scaly, partially vesicular or crusty, erythematous lesions mainly involving the extremities that histopathologically showed peculiar features of focal, total epidermal necrosis accompanied by a lichenoid tissue reaction. He developed the skin eruption after receiving a blood transfusion from his mother when he showed debility induced by vaccination with an alternated live measles virus vaccine. The lesions rapidly regressed after sun exposure. To our knowledge, there has been no report of a similar case despite such unique features. OBSERVATION: We encountered a similar case of columnar epidermal necrosis in a 15-year-old Japanese girl with chronic graft-vs-host disease; the lesions occurred 3 months after the transfusion of peripheral blood stem cells from her HLA antigen-matched brother. However, there was no exacerbation of liver dysfunction, diarrhea, or bone marrow aplasia. The peculiar cutaneous lesions responded well to topical phototherapy. CONCLUSION: These 2 patients shared a similarity in their lesions and circumstances under which the blood transfusion was performed to a debilitated patient from a close family member. We believe that focal epidermal necrosis observed in patients with this condition represents a variant of blood transfusion-associated lichenoid graft-vs-host disease that occurs uniquely in a skin-targeted fashion.

Adolescent↗
PubMed2000

Tumor-targeted chemotherapy with SMANCS in lipiodol for renal cell carcinoma: longer survival with larger size tumors.

OBJECTIVES: To evaluate the anticancer effects of a lipophilic macromolecular anticancer agent, poly(styrene-co-maleic acid)-conjugated neocarzinostatin (SMANCS), dissolved in a lipid contrast medium (Lipiodol) given via the renal artery to patients with renal cell carcinoma. METHODS: Among 467 patients with renal cell carcinoma treated between April 1984 and March 1993, 191 were treated with SMANCS dissolved in a lipid contrast medium (a 3:2 mixture of Lipiodol F and Lipiodol Ultrafluid; Lpd). Selective arterial infusion of SMANCS/Lpd was performed at a dose of 1.0 or 1. 5 mg/mL. The infusion was repeated at intervals of about 2 weeks or longer, but the doses and the total number of infusions varied among patients, according to results of computed tomography analysis. RESULTS: Statistical analysis was performed for 415 patients who met the criteria of this study. Twenty-six surgical patients with metastases who underwent infusion therapy of SMANCS/Lpd for primary lesions showed 3 and 5-year survival rates of 23.0% and 12.8%, respectively; the rates were 19.3% and 9.7% in 31 patients who did not receive SMANCS infusion therapy. In 125 surgical patients without metastases who underwent SMANCS/Lpd infusion, the 5 and 10-year survival rates were 83.0% and 75.2%, respectively, whereas rates of 84.6% and 78.9% were observed in 199 surgical patients whose median tumor size was significantly smaller, however, than the SMANCS/Lpd infusion group. The maximal tumor diameter at the beginning of treatment was significantly larger (mean diameter 70.8 mm) in the SMANCS/Lpd infusion group than in the noninfusion group (59.1 mm). The survival rate was statistically better for patients with tumors of 100 mm diameter or larger in the SMANCS/Lpd infusion group (P <0.05): 5 and 10-year survival rates were 70.4% and 61.6%, respectively, for the infusion group and 64.6% and 50.9% for the group receiving no drug. In patients with larger tumor (greater than 110 mm), the survival rate at 13 years was 75% in the SMANCS/Lpd infusion group and 0% in the surgery group. CONCLUSIONS: Arterial infusion therapy with SMANCS/Lpd appears to be effective for large renal cell carcinoma without metastases in conjunction with surgery.

Adolescent↗
PubMed2000

Fluorinated alcohol, the third group of cosolvents that stabilize the molten-globule state relative to a highly denatured state of cytochrome c.

The effects of 1,1,1,3,3,3-hexafluoro-isopropanol (HFIP) on the conformation of cytochrome c (cyt c) at pH 1.9 were studied using a combination of spectroscopic and physical methods. Analysis varying the HFIP concentration showed that a compact denatured conformation (M(HF)) accumulates in a low concentration range of HFIP in the middle of structural transition from the highly unstructured acid-denatured state to the highly helical alcohol-denatured state of cyt c. This contrasts clearly with the effect of isopropanol (IP), in which no compact conformation accompanied with the transition. Analysis varying concentrations of HFIP and NaCl concurrently showed that the M(HF) state of cyt c is essentially identical to the salt-induced molten-globule (M(G)) state, and the M(G) state in the presence of salt was also stabilized by a low concentration of HFIP. Furthermore, 2,2,2-trifluoroethanol stabilized M(HF) similarly to HFIP, supporting the proposition that the specific effect observed for HFIP is caused by fluorination of alcohol. The mechanism stabilizing compact conformation by HFIP remains unclear, but is probably distinct from that of salts and polyols, which are also known to stabilize the M(G)-like state.

2-Propanol↗
PubMed2000

Myofiber length and myofiber arrangement in the antebrachial and leg muscles of sheep.

The myofibers of the skeletal muscle vary in length in muscle and from muscle to muscle. Information about myofiber length and myofiber arrangement is necessary to understand the architecture of muscles and differences in myofiber length in muscles. The purpose of the present study was to determine myofiber lengths, ratio of myofiber length to muscle length, and myofiber arrangement of the antebrachial and leg muscles in the sheep. The myofibers of the antebrachial muscles ranged from 7.3 mm (m. extensor carpi ulneris, bipennate muscle) to 39.6 mm (m. flexor digitorum profundus caput radiale, unipennate muscle) in length. The myofibers of the leg muscles ranged from 10.0 mm (m. flexor digitorum superficialis, multipennate muscle) to 119.2 mm (m. soleus, fusiform muscle) in length. The ratio of myofiber length to muscle length in the fusiform muscle was higher than that in the uni-, bi-, and multipennate muscles. The unipennate muscles tended to have a higher ratio of myofibers length to muscle length than did the bi- and multipennate muscles. No difference in the ratio of myofiber length to muscle length existed between the bipennate muscles and multipennate muscles.

Animals↗
PubMed1999

Amyloid-like aggregates of a plant protein: a case of a sweet-tasting protein, monellin.

We report here a novel case of amyloid-like aggregation of a plant protein. A sweet-tasting protein, monellin, experiences an irreversible heat denaturation at pH 2.5 and 85 degrees C. Addition of 100 mM NaCl couples this process with protein aggregation. The aggregates were structured as regular fibers with approximately 10 nm width and capable of binding to Congo red, similarly to well-known amyloid fibrils. The amyloid-like aggregation process was also successfully monitored with a calorimetric method. This work supports the universality of the amyloid-like aggregation, not restricted to some special categories of protein.

Amyloid↗
PubMed1999

Grf40, A novel Grb2 family member, is involved in T cell signaling through interaction with SLP-76 and LAT.

We molecularly cloned a new Grb2 family member, named Grf40, containing the common SH3-SH2-SH3 motif. Expression of Grf40 is predominant in hematopoietic cells, particularly T cells. Grf40 binds to the SH2 domain-containing leukocyte protein of 76 kD (SLP-76) via its SH3 domain more tightly than Grb2. Incidentally, Grf40 binds to linker for activation of T cells (LAT) possibly via its SH2 domain. Overexpression of wild-type Grf40 in Jurkat cells induced a significant increase of SLP-76-dependent interleukin (IL)-2 promoter and nuclear factor of activated T cell (NF-AT) activation upon T cell receptor (TCR) stimulation, whereas the COOH-terminal SH3-deleted Grf40 mutant lacked any recognizable increase in IL-2 promoter activity. Furthermore, the SH2-deleted Grf40 mutant led to a marked inhibition of these regulatory activities, the effect of which is apparently stronger than that of the SH2-deleted Grb2 mutant. Our data suggest that Grf40 is an adaptor molecule involved in TCR-mediated signaling through a more efficient interaction than Grb2 with SLP-76 and LAT.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Functional role of interleukin-4 (IL-4) and IL-7 in the development of X-linked severe combined immunodeficiency.

X-linked severe combined immunodeficiency (X-SCID) is characterized by an absent or diminished number of T cells and natural-killer (NK) cells with a normal or elevated number of B cells, and results from mutations of the gammac chain. The gammac chain is shared by interleukin-2 (IL-2), IL-4, IL-7, IL-9, and IL-15 receptors. Recently, a survival signal through the IL-7 receptor alpha (IL-7Ralpha) chain was shown to be important for T-cell development in mice and was suggested to contribute to the X-SCID phenotype. In the present study, we examined function of a mutant gammac chain (A156V) isolated from an X-SCID patient and found that T cells expressing the mutant gammac chain were selectively impaired in their responses to IL-4 or IL-7 compared with the wild-type gammac chain expressing cells although responses to IL-2 or IL-15 were relatively maintained. The result shows that IL-4- and/or IL-7-induced signaling through the gammac chain is critical for T-cell development and plays an important role in the development of the X-SCID phenotype.

Genetic Linkage↗
PubMed1999

Immunological reconstitution by allogeneic bone marrow transplantation in a child with the X-linked hyper-IgM syndrome.

UNLABELLED: A successful transplantation of sibling marrow in a patient with the X-linked hyper-IgM syndrome is reported. Engraftment of HLA-identical marrow cells was obtained, although complicated by grade I acute graft-versus-host disease. Expression of the CD40 ligand (CD40L, CD154) by activated T-cells from the recipient remained at low levels until 10 months after the transplantation, but then normalized. The patient is now fully competent in immune function without any episodes of severe infection 24 months later. CONCLUSION: Allogeneic bone marrow transplantation is a reasonable therapeutic option for X-linked hyper-IgM syndrome if HLA-matched family donors are available. Whether dysregulation of CD40L expression causes post-transplant immunological abnormalities remains to be clarified.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1999

Influence of diet on fatty acids of three subtropical fish, subfamily Caesioninae (Caesio diagramma and C. tile) and family Siganidae (Siganus canaliculatus).

The total lipid and fatty acid compositions of tissues and the stomach contents of three subtropical marine fish species, subfamily Caesioninae, Caesio diagramma and C. tile, and family Siganidae Siganus canaliculatus, were investigated to clarify the differences between these species. Triacylglycerols (TAG) were the dominant depot lipids of the three species, whereas wax esters were found as a minor component. In particular, muscle lipids were found to contain mainly glycerol derivatives such as TAG and phospholipids. The major fatty acids identified in the three species were 16:0, 18:0, 18:1 n-9, and 22:6n-3 (docosahexaenoic acid, DHA). In addition, noticeable levels of 16:1 n-7, 18:1 n-7, 20:4n-6 (arachidonic acid, AA), and 20:5n-3 (eicosapentaenoic acid) were found. DHA was the most abundant polyunsaturated fatty acid (PUFA) in the muscle and viscera lipids of the three species. The high DHA levels in the lipids of all the organs were found to be higher than those of the lipid extracted from the stomach contents of the three fishes. In addition, the specimens of S. canaliculatus contained significantly higher levels of AA in its tissues than did the other two species. A high AA content is unusual since such high levels of n-6 PUFA are rarely found in higher marine organisms. These levels may be due to its characteristic feeding pattern, because S. canaliculatus prefer and mainly feed on seaweed, which often contains high amounts of n-6 PUFA, such as linoleic acid (18:2n-6) and AA.

Animals↗
PubMed1999

Bilateral pneumothoraces with multiple bullae in a patient with asymptomatic bronchiolitis obliterans 10 years after bone marrow transplantation.

A 16-year-old boy developed bronchiolitis obliterans (BO) 10 years after BMT for myelodysplastic syndrome. Although the patient complained of almost no dyspnea on exertion, he had mild hypercapnea with a markedly reduced forced expiratory volume of 0.32 l. Chest X-rays showed occasional bilateral minimal pneumothoraces, which is in accordance with the existence of multiple small bullae found on the pleural surface at video-assisted thoracic surgery. Histologic examination of the biopsied lung revealed BO. This case indicates that BO in adolescence following BMT and possible chronic GVHD may be masked because of lung immaturity at BMT, and BO after BMT may be associated with multiple pleural bullae.

Adolescent↗
PubMed1999

A novel mutant gammac chain from a patient with typical phenotype of X-linked severe combined immunodeficiency (SCID) has partial signalling function for mediating IL-2 and IL-4 receptor action.

Mutations of the common gamma (gammac) chain result in X-linked SCID (X-SCID), which is characterized by the reduction in number or absence of peripheral blood T cells and natural killer (NK) cells, with retention of normal numbers of B cells. In the present study we describe a novel mutant gammac chain of an X-SCID patient with a typical X-SCID phenotype. This mutant receptor subunit is able to associate with Jak3 to transduce a weak signal. The Jak3-specific action is demonstrated by the induction of gene expression through the haematopoietin receptor response element (HRRE) by IL-2 and IL-4 in the experimental model of transiently transfected hepatoma cells over-expressing Jak3. This result suggests that a threshold in the gammac-Jak3 interaction determines the X-SCID phenotype.

Genetic Linkage↗
PubMed1999

The compact and expanded denatured conformations of apomyoglobin in the methanol-water solvent.

We have performed a detailed study of methanol-induced conformational transitions of horse heart apomyoglobin (apoMb) to investigate the existence of the compact and expanded denatured states. A combination of far- and near-ultraviolet circular dichroism, NMR spectroscopy, and small-angle X-ray scattering (SAXS) was used, allowing a phase diagram to be constructed as a function of pH and the methanol concentration. The phase diagram contains four conformational states, the native (N), acid-denatured (U(A)), compact denatured (I(M)), and expanded helical denatured (H) states, and indicates that the compact denatured state (I(M)) is stable under relatively mild denaturing conditions, whereas the expanded denatured states (U(A) and H) are realized under extreme conditions of pH (strong electric repulsion) or alcohol concentration (weak hydrophobic interaction). The results of this study, together with many previous studies in the literature, indicate the general existence of the compact denatured states not only in the salt-pH plane but also in the alcohol-pH plane. Furthermore, to determine the general feature of the H conformation we used several proteins including ubiquitin, ribonuclease A, alpha-lactalbumin, beta-lactoglobulin, and Streptomyces subtilisin inhibitor (SSI) in addition to apoMb. SAXS studies of these proteins in 60% methanol showed that the H states of these all proteins have expanded and nonglobular conformations. The qualitative agreement of the experimental data with computer-simulated Kratky profiles also supports this structural feature of the H state.

Apoproteins↗
PubMed1999

PCR-RFLP analysis of cytomegalovirus infections associated with bone marrow transplantation in Japanese children.

In order to investigate the longitudinal molecular epidemiology of cytomegalovirus (CMV) infections associated with bone marrow transplantation (BMT) in Japanese children, we analyzed 36 CMV strains from 11 cases. Three regions (DNA polymerase, glycoprotein H, and immediate-early regions) of CMV DNA were amplified by polymerase chain reaction (PCR), and amplified products were each digested with two restriction enzymes, followed by electrophoresis. These restriction fragment length polymorphism (RFLP) analyses allowed the differentiation of 36 strains into 13 genotypes. Each patient excreted his or her own CMV with distinct genotype over the study period of up to one year. CMVs of two different genotypes were recovered during a one-month study from one recipient, who received a peripheral blood stem cell transplantation. Although the majority of patients and donors were CMV-seropositive before BMT, multiple CMV infections might not be common and the reactivation of latently infected CMV might be prominent in Japanese children receiving transplants.

Adolescent↗
PubMed1998

Localization in the II-III loop of the dihydropyridine receptor of a sequence critical for excitation-contraction coupling.

Skeletal and cardiac muscles express distinct isoforms of the dihydropyridine receptor (DHPR), a type of voltage-gated Ca2+ channel that is important for excitation-contraction (EC) coupling. However, entry of Ca2+ through the channel is not required for skeletal muscle-type EC coupling. Previous work (Tanabe, T., Beam, K. G., Adams, B. A., Niidome, T., and Numa, S. (1990) Nature 346, 567-569) revealed that the loop between repeats II and III (II-III loop) is an important determinant of skeletal-type EC coupling. In the present study we have further dissected the regions of the II-III loop critical for skeletal-type EC coupling by expression of cDNA constructs in dysgenic myotubes. Because Ser687 of the skeletal II-III loop has been reported to be rapidly phosphorylated in vitro, we substituted this serine with alanine, the corresponding cardiac residue. This alanine-substituted skeletal DHPR retained the ability to mediate skeletal-type EC coupling. Weak skeletal-type EC coupling was produced by a chimeric DHPR, which was entirely cardiac except for a small amount of skeletal sequence (residues 725-742) in the II-III loop. Skeletal-type coupling was stronger when both residues 725-742 and adjacent residues were skeletal (e.g. a chimera containing skeletal residues 711-765). However, residues 725-742 appeared to be critical because skeletal-type coupling was not produced either by a chimera with skeletal residues 711-732 or by one with skeletal residues 734-765.

Amino Acid Sequence↗
PubMed1998

The Ah receptor is not involved in 2,3,7,8-tetrachlorodibenzo- p-dioxin-mediated apoptosis in human leukemic T cell lines.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a common environmental pollutant causing public concern. Its toxic effects include disruption of the immune, endocrine, and reproductive systems, impairment of fetal development, carcinogenicity, and lethality in rodents. Here, we report that TCDD induces apoptosis in two cultured human leukemic lymphoblastic T cell lines. This cell death was found not to be dependent on an aryl hydrocarbon receptor and to be inhibited by the inhibitor of tyrosine kinases and caspases. Apoptosis-linked c-Jun N-terminal kinase is rapidly activated in these cells by the treatment with TCDD. A dominant-negative mutant of c-Jun N-terminal kinase prevented cell death in the treatment with TCDD. Furthermore, TCDD decreases the Bcl-2 protein level in these cell lines. These findings will help in the understanding of the molecular mechanism underlying TCDD-mediated immunotoxicity.

Apoptosis↗