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Biomedical subjects

K Hayakawa

Publications and source records attributed to K Hayakawa.

At least 145 records · Page 8Linked to original sources
PubMed1998

Cytotoxic effect of paclitaxel (taxol) either alone or in combination with irradiation in two rat yolk sac tumour cell lines with different radiosensitivities in vitro.

PURPOSE: To investigate the differences between two rat yolk sac tumour cell lines with different radiosensitivities in paclitaxel sensitivity and in the sensitizing effects of paclitaxel in combination with irradiation. MATERIALS AND METHODS: NMT-1 is a parent radiosensitive cell line and NMT-1R is a variant radioresistant cell line. RESULTS: Clonogenic assay demonstrated almost the same paclitaxel sensitivity with Do of 5.15 nM in NMT-1 and 5.02 nM in NMT-1R. Many apoptotic cells and DNA ladder formations were observed at 24 h after exposure to paclitaxel in both cell lines. The incidence of DNA fragmentation after 24 h exposure to 20 nM paclitaxel was 12.4 +/- 3.3% for NMT-1, and 13.0 +/- 1.9% for NMT-1R. Paclitaxel showed a supra-additive effect in combination with irradiation in both cell lines at 12 h after paclitaxel treatment only when the accumulation of cells in the G2/M phase reached its peak. CONCLUSIONS: Paclitaxel had the same cytotoxic effect in two cell lines with different radiosensitivity due to the induction of apoptosis. A supra-additive effect to radiation was observed with 12 h pretreatment in both cell lines. Paclitaxel may be effective for tumours with a component of different radiosensitivity in combination with irradiation.

Animals↗
PubMed1998

Significance of water solubility in the gastrointestinal absorption of trans-bis(n-valerato)(1R,2R-cyclohexanediamine)(oxalato)platinum(IV), an orally active antitumor platinum complex, and its analogs.

Trans-bis(n-valerato)(1R,2R-cyclohexanediamine)(oxalato++ +)platinum(IV) (C5-OHP) is an orally active platinum complex we prepared. The gastrointestinal absorption of C5-OHP was examined in rats and compared with those of C5-OHP analogs which have a general formula of trans-bis(n-OCOCnH2n+1)(1R,2R-cyclohexanediamine)(oxalato )platinum(IV) as well as C5-OHP. The complexes did not show significant differences in pharmacokinetic behavior after i.v. injection. Plasma platinum level after a single oral administration at a dose was higher for a complex with higher water solubility. The intestinal absorption rate measured by an in situ recirculating perfusion technique was higher for a complex with higher lipophilicity. These results indicate that the water solubility is a more dominant factor than the lipophilicity in the gastrointestinal absorption of the complexes. Then, the effects of surfactants and alpha-cyclodextrin (alpha-CD) on the solubility of C5-OHP was studied. Among the agents tested, alpha-CD showed the highest effect in increasing the solubility. Administration of C5-OHP together with alpha-CD gave approximately three times higher plasma platinum levels than administration of C5-OHP alone. Water solubility was found to be a dominant factor in the gastrointestinal absorption of C5-OHP and its analogs.

Animals↗
PubMed1998

Characterization of a granule-bound starch synthase isoform found in the pericarp of wheat.

Waxy wheat (Triticum aestivum L.) lacks the waxy protein, which is also known as granule-bound starch synthase I (GBSSI). The starch granules of waxy wheat endosperm and pollen do not contain amylose and therefore stain red-brown with iodine. However, we observed that starch from pericarp tissue of waxy wheat stained blue-black and contained amylose. Significantly higher starch synthase activity was detected in pericarp starch granules than in endosperm starch granules. A granule-bound protein that differed from GBSSI in molecular mass and isoelectric point was detected in the pericarp starch granules but not in granules from endosperm. This protein was designated GBSSII. The N-terminal amino acid sequence of GBSSII, although not identical to wheat GBSSI, showed strong homology to waxy proteins or GBSSIs of cereals and potato, and contained the motif KTGGL, which is the putative substrate-binding site of GBSSI of plants and of glycogen synthase of Escherichia coli. GBSSII cross-reacted specifically with antisera raised against potato and maize GBSSI. This study indicates that GBSSI and GBSSII are expressed in a tissue-specific manner in different organs, with GBSSII having an important function in amylose synthesis in the pericarp.

Amino Acid Sequence↗
PubMed1998

Sialoglycoconjugates in primary and recurrent mixed tumors of lacrimal glands.

We examined the activity of Griffonia simplicifolia II agglutinin (GS2) before and after neuraminidase treatment in 2 cases of primary benign mixed tumor (BMT) and a case of recurrent mixed tumor (MT). Histologically, each type of MT is comprised of epithelial and mesenchymal components. GS2, which showed no binding to either structural component in the primary BMT, was specifically bound to the mesenchymal component in the recurrent MT. After neuraminidase treatment, there was a marked increase in GS2-binding levels in the epithelial component of the primary BMT and in both components of the recurrent MT. These results might reveal a prominent sialylation in the recurrent MT.

Adult↗
PubMed1998

Bronchial asthma induced by rice.

A 43-year-old patient with rice-induced bronchial asthma was first admitted to our hospital for developing bronchial asthma induced by mite and house dust. At that time, there was no sign of allergic response to rice. Two years later, he was readmitted in an emergency state, with a severe attack of bronchial asthma. This time, however, the result of immunoglobulin E (IgE)-radioallergosorbent test (RAST) for rice was positive, with those to mite and house dust were unexpectedly negative. The causative factors and pathological mechanisms of various kinds of food allergies still remain unknown. The patient is now followed up in an ambulatory setting, and has been eating hypoallergenic rice with no bronchial asthma-induced attack. The present case, being an adult patient with severe grain-induced bronchial asthma previously allergic to mite and house dust, seems to be rather rare in the literature.

Adult↗
PubMed1998

[A girl with transient psychological disturbance caused by orally administered acyclovir--differentiation between acyclovir neurotoxicity and herpes simplex encephalitis].

A previously healthy 7-year-old girl suffered from oral herpetic gingivostomatitis. After four days, oral administration of acyclovir (ACV), 1,000 mg in five divided doses, was started. She became irritable and intermittently delirious next day. Laboratory tests of blood and cerebrospinal fluid (CSF) were within normal limits and EEG showed no abnormality. Brain CT and MRI demonstrated mild asymmetry of the lateral ventricle. SPECT showed low perfusion area in the bilateral thalamus. The titer of IgG and IgM against herpes simplex virus (HSV) was increased in the serum but not in the CSF. A PCR study of HSV DNA was negative in the CSF. ACV was discontinued after 5 days' administration and she recovered from neurological disorders within 48 hours. ACV neurotoxicity is self-limiting and dose-dependent. It may be distinguished from herpes simplex encephalitis by the lack of fever, headache, focal neurologic signs, and abnormal CSF and neuroradiological findings. However, when the differentiation should be difficult, we believe that the administration of ACV can be carefully continued because the potential fatality of HSE is high while ACV neurotoxicity is reversible.

Acyclovir↗
PubMed1997

The structure and function of the actin-binding domain of myosin light chain kinase of smooth muscle.

In addition to its kinase activity, the myosin light chain kinase (MLCK) of smooth muscle has an actin binding activity through which it can regulate the actin-myosin interaction of smooth muscle (Kohama, K., Okagaki, T., Hayakawa, K., Lin, Y., Ishikawa, R., Shimmen, T., and Inoue, A. (1992) Biochem. Biophys. Res. Commun. 184, 1204-1211). In this study, we have analyzed the actin binding activity of MLCK and related it to its amino acid sequence by producing native and recombinant fragments of MLCK. Parent MLCK exhibited both calcium ion (Ca2+) and calmodulin (Ca2+/CaM)-sensitive and Ca2+/CaM-insensitive binding to actin filaments. The native fragment, which consists of the Met1-Lys114 sequence (Kanoh, S., Ito, M., Niwa, E., Kawano, Y., and Hartshorne, D. J. (1993) Biochemistry 32, 8902-8907), and the recombinant NN fragment, which contains this 1-114 sequence, showed only Ca2+/CaM-sensitive binding. An inhibitory effect of the NN fragment on the actin-myosin interaction was observed by assaying in vitro motility and by measuring the actin-activated ATPase activity of myosin. The recombinant NN/41 fragment, which is constructed without the Met1-Pro41 sequence of the NN fragment, lost both the actin binding activity and the inhibitory effect. We confirmed the importance of the 1-41 sequence by using a few synthetic peptides to compete against the NN fragment in binding to actin filaments. The experiments using recombinant fragments and synthetic peptides also revealed that the site for CaM-binding is the Pro26-Pro41 sequence. The site for the Ca2+/CaM-insensitive binding, which is shown to be localized between the Ca2+/CaM-sensitive site and the central kinase domain of MLCK, exerted no regulatory effects on the actin-myosin interaction.

Actins↗
PubMed1997

Outcome of radiation therapy for patients with Kasabach-Merritt syndrome.

PURPOSE: The efficacy of radiation therapy for Kasabach-Merritt syndrome, which is characterized by a huge hemangioma with consumption coagulopathy, remains controversial. In this study, we retrospectively investigated the treatment outcome of radiation therapy for seven neonates with Kasabach-Merritt syndrome. METHODS AND MATERIALS: During the past 25 years we have seen seven children with Kasabach-Merritt syndrome who were treated with radiation therapy. Their ages ranged from 1 day to 5 months, with a median age of 1 month. The hemangioma was located in the extremities in four of seven children. Tumor sizes ranged from 70 cm to more than 150 cm in greatest diameter. Initial platelet counts were all less than 40,000/mm3 except for one patient. In principle, the total dose applied to the hemangioma was 8-10 Gy, with a daily dose of 1 Gy five times a week. RESULTS: Four of seven hemangiomas responded dramatically, with a concomitant rise of the platelet count to radiation therapy. Although the remaining three hemangiomas, all of which were ill circumscribed by widespread overlying shiny, dusky purple skin, became less tense during radiation therapy. Disseminated intravascular coagulopathy was not improved, but they have responded favorably to two or three courses of radiation therapy with an extended radiation field by 1.5 years of age. As a result, all seven patients are now surviving with no evidence of hemangioma or hematological abnormalities. Shortening of the extremity was observed in three patients who received multiple courses of radiation therapy. CONCLUSIONS: Radiation therapy appears to be one of the effective treatment options for Kasabach-Merritt syndrome despite the risk of growth delay and malignancy.

Disseminated Intravascular Coagulation↗
PubMed1997

Repeated elicitation of contact hypersensitivity induces a shift in cutaneous cytokine milieu from a T helper cell type 1 to a T helper cell type 2 profile.

We previously demonstrated that repeated application of 2,4,6-trinitro-1-chlorobenzene resulted in a site-restricted shift in the time course of Ag-specific hypersensitivity responses from a typical delayed-type to an early-type response. Here we demonstrated that the cutaneous microenvironment at the time of Ag presentation to T cells in the elicitation, but not the induction, phase of contact hypersensitivity is responsible for the shift. To investigate the differences in the cutaneous cytokine milieu between the acute and chronic phases of contact hypersensitivity, sequential cytokine dynamics after 2,4,6-trinitro-1-chlorobenzene application were assessed in the acute vs chronic lesions. In the acute lesions, increased mRNA levels for IFN-gamma and IL-2 were rapidly detected at 1 h and remained elevated at 12 h, while mRNA expression for IL-4 and IL-10 was minimally up-regulated between approximately 12 and 24 h. In chronic lesions, high levels of constitutive expression of IL-4 mRNA were observed and IL-10 mRNA was dramatically up-regulated at 1 approximately 3 h in an Ag-specific fashion, whereas the expression of Th1-type cytokines was markedly reduced. Increased mRNA levels for Th2-type cytokines in the chronic lesions was also reflected at the protein level. These results indicate that repeated elicitation with Ag alters the balance of cytokines released locally, with a shift toward Th2-dominated responses, which would represent the natural evolution processes directed toward reducing a more deleterious Th1 response.

Administration, Cutaneous↗
PubMed1997

Serum protein determination by high-performance gel-permeation chromatography.

A general high-performance gel-permeation chromatography (HPGPC) method was developed to determine protein in human serum with improved sensitivity and speed. The optimum UV wavelength for protein detection was found to be 210 nm, by comparing the protein values obtained by varying the UV wavelength of the HPLC detection system with the protein values obtained from spectrophotometric protein assays, i.e., the bicinchoninic acid (BCA) method and the biuret method. The analysis time was less than 1 min. Since this HPGPC serum protein assay method is simple and rapid, it is expected to be particularly well adapted for use in clinical laboratories.

Adolescent↗
PubMed1997

Circularly permuted beta-lactamase from Staphylococcus aureus PC1.

The role that domain flexibility plays in the enzymatic activity of beta-lactamase from Staphylococcus aureus PC1 was investigated by producing two circularly permuted molecules. The C- and N-termini of the wild-type enzyme are adjacent to each other and remote from the active site, which is located between two domains. The polypeptide chain crosses over from one domain to the other twice. For the circularly permuted molecules, the termini were joined by an eight amino acid residue insertion, and new termini were introduced elsewhere. The first construct, termed cp254, was cleaved in a loop remote from the domain interface. The crystal structure of cp254 has been determined and refined at 1.8 A resolution, revealing essentially the same structure as that of the native protein. The activity profile with a representative sample of beta-lactam antibiotics is also very similar to that of wild-type beta-lactamase. The termini of the second circularly permuted mutant, cp228, occur within the second crossover region and therefore may enhance the flexibility of the molecule. Cp228 beta-lactamase shows a large decrease in enzymatic activity toward the sample of beta-lactam antibiotics, with catalytic rates that are 0.5-1% of those of the wild-type enzyme. One exception is the hydrolysis of the third generation cephalosporin, cefotaxime, which is hydrolyzed by the cp228 enzyme 10-fold faster than by wild-type beta-lactamase. Cp228 has not been crystallized. However, the circular dichroism spectra of the two circularly permuted proteins are very similar, indicating that, by analogy to cp254, cp228 adopts a global folded state. Thermal denaturation experiments reveal that cp254 is somewhat less stable than the wild-type enzyme, whereas cp228 is substantially less stable. Together, the data highlight the profound consequences that introducing flexibility at the domain interface has on both enzyme activity and protein stability.

Amino Acid Sequence↗
PubMed1997

Magnetic resonance imaging of skeletal muscles in the polymyositis.

Magnetic resonance imaging of skeletal muscles was performed in 11 patients with polymyositis. Two types of muscle lesions were revealed. The first, inflammation, showed increased signal intensity on T2-weighted images and iso-intensity on T1-weighted images. The second, fatty replacement, showed increased signal intensity on both images. The coronal sections could elucidate the extension of the lesion in each affected muscle. Inflammation was relatively diffuse, while homogeneous fatty replacement tended to begin at the lower myotendinous junctions.

Adipose Tissue↗
PubMed1997

Rapid rise in FDG uptake in an irradiated human tumour xenograft.

In order to investigate early changes in the glucose metabolism of irradiated tumours, tumour uptake of 2-[18F]fluoro-2-deoxy-d-glucose (18FDG) was studied in human tumour xenografts. Three human tumour lines [ependymoblastoma (NNE), small cell lung cancer (GLS), and glioblastoma (KYG)] showing different radiosensitivities and incidences of radiation-induced apoptosis were subcutaneously transplanted into nude mice, and were irradiated at a single dose of 10 Gy. Then 0.5 mCi of 18FDG was intravenously administered 1 h before sacrifice. The animals were sacrificed at 2, 4 and 6 h following irradiation, and 18FDG accumulation in the tumours was examined. Before irradiation, GLS and KYG tumours showed significantly higher rates of 18FDG accumulation compared with NNE tumours (P <0.004 and P <0.001, respectively). NNE (the most radiosensitive tumour with the highest incidence of radiation-induced apoptosis), however, displayed a 2.3-fold higher rate of 18FDG accumulation at 2 h following irradiation compared with a non-irradiated group (P <0.01), and thereafter showed a plateau up to 6 h. The accumulation did not increase significantly in the other tumours with lower radiosensitivity and much less radiation-induced apoptosis. The rapidity of the increase in 18FDG accumulation in the most radiosensitive tumour line, occurring as early as 2 h following irradiation, suggests that the increase was independent of recovery phenomena following radiation damage.

Animals↗