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Biomedical subjects

T Konno

Publications and source records attributed to T Konno.

At least 37 records · Page 2Linked to original sources
PubMed2001

High-Performance liquid chromatographic analysis of lactone and hydroxy acid of new antitumor drug, DX-8951 (exatecan), in mouse plasma.

A sensitive high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of lactone and total drug (lactone plus hydroxy-acid) of DX-8951 in mouse plasma. Solid-phase extraction by C18 cartridge separated lactone from total drug of DX-8951. Analysis was performed using a reverse-phase ODS column with a mobile phase consisting of acetonitrile/0.05 M potassium dihydrogen phosphate (pH 3) (18: 82, v/v) at a flow rate of 1 ml/min. The limits of quantitation of lactone and total drug were 3 ng/ml in plasma and a linear range of determination were observed over the concentration of 3 to 500 ng/ml. This method was applied to pharmacokinetic study in male mice treated with a single intravenous administration of either lactone or hydroxy-acid of DX-8951. The plasma concentrations of lactone from 2 to 6 h after dosing were similar regardless of the form of DX-8951 administered.

Animals↗
PubMed2001

Systolic dysfunction and blood pressure responses to supine exercise in patients with hypertrophic cardiomyopathy.

Left ventricular function and blood pressure responses were evaluated in 56 patients with non-obstructive hypertrophic cardiomyopathy (HCM) and 12 control subjects by using a radionuclide ventricular function monitor during supine ergometer exercise. Patients with HCM were divided into 2 groups: (i) group A had no decrease in ejection fraction (EF) during exercise; and (ii) group B had a decrease in EF during exercise. During exercise, the change in end-diastolic volume did not differ between the 3 groups. In contrast, the change in end-systolic volume differed between the 3 groups (p<0.0001). The change in systolic blood pressure (SBP) also differed significantly between the 3 groups. The change in SBP in group B was smaller than that in the control group and group A, and changes in the EF and changes in the SBP between rest and peak exercise showed a significant correlation (p<0.005). These results suggest that exercise-induced systolic dysfunction in patients with non-obstructive HCM may contribute to abnormal blood pressure response in those patients.

Adult↗
PubMed2001

Improved survival of children with advanced neuroblastoma treated by intensified therapy including myeloablative chemotherapy with stem cell transplantation: a retrospective analysis from the Tohoku Neuroblastoma Study Group.

In the hospitals of the Tohoku Neuroblastoma Study Group (TNBSG), treatment for children with advanced neuroblastoma (NB) was intensified in the mid-1990's with the introduction of myeloablative therapy (MT) with stem cell transplantation (SCT) including the use of autologous peripheral blood stem cells (PBSC) and bone marrow transplantation (BMT). In this report, we examined whether the intensified therapy improved the outcome of children with advanced NB (age> 12 months) who were diagnosed between 1991 and 1997. Patients were 36 children (23 boys and 13 girls) with an average age of 3.4 years (range; 1 to 14 years). Six of them had stage III disease, and the other 30 had stage IV. They were treated initially with induction chemotherapy, surgery, and post-operative chemoradiotherapy, after which 17 of them continued further chemotherapy and the other 19 received MT/SCT (18 with PBSCT and 1 with BMT). Progression-free survival (PFS) rate at seven years from diagnosis was 43.5% for all patients, 66.7% for stage III patients and 38.2% for stage IV patients. The difference between stage III and IV patients was not significant. Among the 30 patients with stage IV disease, PFS at seven years was significantly higher in the 19 patients who received MT/SCT (55.6%) than in the 11 patients who did not receive it (12.5%). There was no difference in clinical and biological risk factors between these two groups, except for the proportion of patients with favorable response to initial therapy (36% and 80% for patients without and with MT/SCT, respectively). Furthermore, the proportion of patients with N-myc amplification was significantly higher in patients with progressive disease (PD) after MT/SCT than in those in CR after MT/SCT. The results of this retrospective study of children with advanced NB suggest that therapy intensification involving MT/SCT might result in lengthened survival time for patients with stage IV disease, and that post-transplant PD remains a risk for patients with high levels of N-myc amplification.

Antineoplastic Agents↗
PubMed2000

Pressure effect on the conformational fluctuation of apomyoglobin in the native state.

We have investigated the effect of pressure on fluctuations of the native state of sperm whale apomyoglobin (apoMb) by H/D exchange, fluorescence, and limited proteolysis. The results from intrinsic fluorescence showed that a large fraction of apoMb molecules is in the native conformation in the pressure range from 0.1 to 150 MPa at 293 K and pH 6.0. The H/D exchange of protons of the individual backbone amino acids in this pressure range was monitored by NMR. The rate of H/D exchange was enhanced at high pressure, with the protection factors for some residues decreasing by factors of more than 100 compared to the values at 0.1 MPa. The amplitude of the decrease of the protection factor varied among the individual amino acids on the same secondary structure unit. This result suggests that H/D exchange in apoMb is explained best by the penetration model, in which solvent penetrates into the protein matrix via small motions. The result from limited proteolysis under high pressure showed that a pressure increase does not induce local unfolding of the secondary structure units of apoMb. Conformational fluctuations much smaller than local unfolding evidently provide pathways for water to diffuse into the protein interior, and are enhanced by an increase of pressure.

Animals↗
PubMed2000

A new alternative method to quantify residual structure in 'unfolded' proteins.

Pig (pCSD1) and human (hCSD1) calpastatin domain 1 proteins were studied to characterize common features of the denatured state of proteins. These proteins were chosen for the present investigation, because pCSD1 was suggested previously to be unstructured in water even at 25 degrees C (1) [T. Konno et al., Biochim. Biophys. Acta 1342 (1997) 73-82]. hCSD1 could be expected to exhibit similar features on the basis of preliminary spectroscopic studies. In the present study, the experimental grounds for the estimate of residual structure in the unfolded state were differential scanning calorimetry heat capacity and circular dichroism (CD) measurements over the temperature range 10-80 degrees C. At selected temperatures, we studied also the effect of guanidinium hydrochloride (GdnHCl) which is known to promote further unfolding of the polypeptide chain. All other measurements were performed at pH 6 in pure water. The present results support the conclusion that the comparison of the experimentally obtained heat capacity data with theoretical heat capacity values calculated on the basis of a newly established increment system gives insight into the degree of hydration of the unfolded polypeptide chain. The percentage by which the experimental heat capacity of the unfolded polypeptide chain differs from the calculated heat capacity permits a quantitative estimate of the residual structure. This estimate is in good agreement with that based on CD absorption. The heat capacity approach has the advantage of comparing fully hydrated and partially hydrated residues in the same aqueous environment, whereas for example spectroscopic measurements, such as CD, are generally referred to the fully unfolded chain in concentrated urea or GdnHCl solutions. As the unfolded chains of pCSD1 and hCSD1 exhibit a smaller heat capacity than that calculated on the new peptide-based increment system [M. Häckel et al., J. Mol. Biol. 291 (1999) 197-213], we conclude that the residues in the unfolded polypeptide chain are less hydrated than the same residues in oligopeptides. This suboptimal hydration is the result of residual structure in the chain as observed in both CD and heat capacity measurements.

Amino Acid Sequence↗
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

Synthesis, characterization, and chiral properties of CoIII2AgI3 pentanuclear, CoIII4ZnII4 octanuclear, and CoIII mononuclear complexes with aza-capped hexadentate-N3S3 thiolate ligands: crystal structures of.

The reaction of an S-bridged Co2(III)Ag3(I) pentanuclear complex, [Ag3[Co(aet)3]2][BF4]3 (aet = NH2CH2CH2S-), with paraformaldehyde in basic acetonitrile, followed by adding aqueous ammonia, produced an aza-capped Co2(III)-Ag3(I) complex, [Ag3[Co(L)]2]3+ ([1]3+) (L = N(CH2NHCH2CH2S-)3). The crystal structure of [1]3+ was determined by X-ray crystallography. [1][PF6]3 x H2O, empirical formula C18H44Ag3Co2F18N8OP3S6, crystallizes in the tetragonal space group 142m with a = 13.012(1) A, c = 24.707(2) A, and Z = 4. In [1]3+ the two aza-capped [Co(L)] units are linked by three Ag(I) atoms, such that the two Co(III) atoms are encapsulated in a macrobicyclic metallocage, [Ag3(I)(L)2]3-. [1]3+ was converted to an aza-capped Co4(III)Zn4(II) octanuclear complex, [Zn4O[Co(L)]4]6+ ([2]6+), by reaction with I- in the presence of Zn2+ and ZnO in water. The crystal structure of [2]6+ was also determined by X-ray crystallography. [2][PF6]6 x 8H2O, empirical formula C36H100Co4F36N16O9P6S12Zn4, crystallizes in the monoclinic space group P2(1/n) with a = 14.33(7) A, b = 25.67(10) A, c = 24.83(6) A, beta = 101.3(3) degrees , and Z = 4. In [2]6+ each of four [Co(L)] units is bound to each trigonal Zn3(II) face of the tetrahedral [Zn4(II)O]6+ core, such that each Co(III) atom is encapsulated in a macrobicyclic [Zn4(II)O(L)] fragment. Treatment of [2]6+ with a basic aqueous solution resulted in a cleavage of the Zn-S bonds to produce an aza-capped Co(III) mononuclear complex, [Co(L)] ([3]), from which [1]3+ is readily reproduced by the reaction with Ag+ in water. All the reactions were found to proceed with retention of the absolute configuration (delta or lambda) of the Co(III) chiral centers; deltadelta-[1]3+, deltadeltadeltadelta-[2]6+, and A-[3] were derived from deltadelta-[Ag3[Co(aet)3]2]3+. The contributions to circular dichroism (CD) from the triple helicity in [1]3+, besides from the asymmetric N and S donor atoms and the Co(III) chiral centers in [1]3+ and [2]6+, were estimated by comparing the CD spectra of deltadelta-[1]3+, deltadeltadeltadelta-[2]6+, and delta-[3].

Journal Article↗
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↗