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Biomedical subjects

K Yoshikawa

Publications and source records attributed to K Yoshikawa.

At least 91 records · Page 5Linked to original sources
PubMed2001

Inhibition of aminopeptidase N (AP-N) and urokinase-type plasminogen activator (uPA) by zinc suppresses the invasion activity in human urological cancer cells.

Zinc is an essential heavy metal and is more abundant in human prostate and kidney than in other tissues. The effects of zinc on the invasion activity of human prostate and renal cancer cell lines, PC-3, LNCaP and SKRC-1, were investigated in vitro using a Transwell cell-culture chamber and were compared with specific protease inhibitors for MMPs, uPA and AP-N, respectively. The invasion activity of PC-3 cells was effectively suppressed by zinc and by all protease inhibitors in a dose-dependent manner. The invasion activity of LNCaP cells was almost unaffected by these inhibitors. In SKRC-1 cells, the invasion activity was strongly suppressed by MP03, although a moderate inhibition by zinc and bestatin was observed. The purified AP-N activity was strongly inhibited by zinc at a concentration similar to that suppressing the invasion activity of PC-3 cells and this inhibition by zinc was apparently competitive. Although the purified uPA activity was also inhibited by zinc, this inhibition was uncompetitive. AP-N was expressed abundantly on the membrane fraction of PC-3 cells among these cells tested, while its expression on the membrane fraction of SKRC-1 cells was weaker than that of PC-3 cells. The expression of uPA was also highest on the membrane fraction of PC-3 cells. These results suggest that AP-N and uPA may be involved in the invasion of human prostate cancer cells and that zinc probably participates in the invasion and metastasis of cancer cells through the regulation of the enzymatic activity of AP-N and uPA in human cancerous prostate.

Adenocarcinoma↗
PubMed2001

Two new steroidal derivatives from the fruit body of Chlorophyllum molybdites.

Two new steroid derivatives, (22E,24R)-3alpha-ureido-ergosta-4,6,8(14),22-tetraene (1) and (22E,24R)-5alpha,8alpha-epidioxyergosta-6,9,22-triene-3beta-ol 3-O-beta-D-glucopyranoside (2) were isolated from the fruit bodies of Chlorophyllum molybdites (Agaricaceae). The structures were established by spectroscopic and chemical methods. These compounds exhibited cytotoxicity against Kato III cells.

Agaricales↗
PubMed2001

A benzofuran glycoside and an acetylenic acid from the fungus Laetiporus sulphureus var. miniatus.

A new benzofuran glycoside, masutakeside I (1) and a new C10 acetylenic acid, masutakic acid A (2) were isolated from the fruiting bodies of the fungus Laetiporus sulphureus var. miniatus. Their structures were established by spectroscopic and chemical methods. The known compounds 3-6 were also obtained and identified as egonol, demethoxyegonol, egonol glucoside and egonol gentiobioside. Some of these compounds exhibited cytotoxicity against Kato III cells.

Alkynes↗
PubMed2001

Molecular cloning, DNA sequence, and expression of the gene encoding for thermostable pectate lyase of thermophilic Bacillus sp. TS 47.

The gene that encodes a thermostable pectate lyase (called PL 47), from Bacillus sp. TS 47, was cloned, sequenced, and expressed in mesophilic B. subtilis. The gene contained an open reading frame consisting of 1326 bp, which encoded 441 amino acids. The deduced amino acid sequence of the mature enzyme (416 amino acids with a calculated molecular mass of 47,262 Da), showed 52% similarity with PL (BsPel) from mesophilic B. subtilis SO113. The structure-based alignment of the deduced amino acid sequence of PL 47 with that of BsPel suggested that PL 47 might have a parallel beta-helix structure with three long loops. The amino acids making up PL 47 are richer in hydrophobic amino acids and glutamic acid than BsPel. The hydropathy profile of PL 47 indicated that the amino acid sequences around putative calcium binding sites are more hydrophobic than the same region of BsPel. The gene product expressed in B. subtilis as the host was stable up to 70 degrees C and the reaction was optimal around 70 degrees C, as well as native PL 47.

Amino Acid Sequence↗
PubMed2001

Justification of measurement of eight congeners levels instead of twenty congeners of dioxins for mass screening of human exposure.

Measurement of blood dioxin levels to monitor human exposure is tedious and expensive work, although high-resolution mass spectrometers equipped with high-resolution gas chromatography are becoming relatively common in Japan. The Ministry of Health and Welfare and the Environmental Agency require measurement of 17 dioxins, seven PCDDs and 10 PCDFs, according to a statement in "Dioxin Measurement Guidelines" published in 1997. Additionally, three coplanar polychlorinated biphenyls, for which TEFs were determined, have been included for measurement ad libitum. Recently, we have examined 316 blood samples from four groups of subjects, living in areas 5 km away from any incinerator (A), within 2 km from incinerators that emitted slightly higher levels of dioxins than the allowed level (higher than 80 ng/Nm3) (B), within 2 km of an incinerator which emitted a high level of dioxin (C), and workers at this incinerator (D), for dioxin levels by measuring 20 congeners, including three coplanar PCBs. The average pg TEQ/g lipid values were 23.8 +/- 12.3, 25.6 +/- 11.6, 39.1 +/- 18.8 and 100.7 +/- 127.4 for A, B, C and D, respectively. It was found that more than 90% of the total TEQs of the subjects in all groups were accounted for by eight congeners, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, 3,3',4,4',5-PeCB, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF and 2,3,4,6,7,8-HxCDF. This is also the case for a further 30 blood samples that had no connection with incinerators. Further, regression analysis of the 346 samples leads to an equation of y = 1.109x - 1.077, with a correlation coefficient, r = 0.9996. Here, y = total pg TEQ of 20 congeners/g lipid of blood, and x = total pg TEQs of eight congeners/g lipid. Accordingly, we propose that measurement of eight instead of 20 congeners is appropriate to obtain dioxin TEQ values of blood, at low cost, with high accuracy and with high efficiency, in a short time.

Adult↗
PubMed2001

CA19-9-producing transitional cell carcinoma of the renal pelvis: a case report.

We report a case of CA19-9-producing transitional cell carcinoma of the renal pelvis. A 59-year-old male patient with left hydronephrosis was referred to us from a local physician. Retrograde pyelogram revealed irregular filling defects involving calices, pelvis and proximal ureter. The serum CA19-9 level was elevated. Under the diagnosis of renal pelvic tumor, we performed radical left nephroureterectomy. The tumor was histologically diagnosed as transitional cell carcinoma. The tumor cells showed positive immunostaining for CA19-9. The serum CA19-9 level was normalized after the operation. To our knowledge, this is the 28th case of a CA19-9-producing tumor in the Japanese literature.

CA-19-9 Antigen↗
PubMed2001

Metabolism of 99mTc-ethylcysteinate dimer in infarcted brain tissue of rats.

UNLABELLED: Brain SPECT with 99mTc-ethylcysteinate dimer (99mTc-ECD) reveals a subacute cerebral infarct as a hypoactive area, even in the presence of postischemic hyperperfusion. The brain retention of 99mTc-ECD depends on hydrophilic conversion mediated by enzymes, and impaired enzymatic trapping is hypothesized to depress the retention efficiency in the infarcted region. The aim of this study was to determine whether the metabolic rate of 99mTc-ECD is actually reduced in infarcted brain tissue. METHODS: In 50 mmol/L phosphate buffer (pH 7.4), 99mTc-ECD was incubated for 30 min with homogenates of rat brain tissue with and without triphenyltetrazolium chloride (TTC) staining. The ratio of polar products was determined by thin-layer chromatography as a function of incubation time, and metabolic rates were obtained. Permanent focal ischemia was induced by occlusion of the right middle cerebral artery (MCA) in rats. The brain was removed 24 h after MCA occlusion, and the infarcted area was defined by TTC staining. The metabolic rate of 99mTc-ECD was determined in homogenates of infarcted tissue, contralateral noninfarcted tissue, and tissue sampled from sham-operated rats. The infarct volume was measured by direct and indirect methods to assess volume expansion caused by edema, and the metabolic rate in infarcted tissue was corrected for the effect of edema. RESULTS: TTC staining had no effect on the metabolic rate of 99mTc-ECD. The metabolic rates in the infarcted tissue were 0.222%/min +/- 0.054%/min and 0.285%/min +/- 0.064%/min before and after correction for edema, respectively. These rates were significantly lower than those in the contralateral noninfarcted tissue (0.426%/min +/- 0.028%/min) and the tissue sampled from the sham-operated rats (0.439%/min +/- 0.031%/min). No substantial difference in rates was observed between the contralateral tissue and the tissue from the sham-operated rats. CONCLUSION: The results of this study showed that infarction decreases the activity of enzymes that mediate the hydrophilic conversion of 99mTc-ECD in the brain and suggest that reduced metabolic activity is related to decreased accumulation of 99mTc-ECD in hyperperfused infarcts.

Animals↗
PubMed2001

Biodegradation of poly(tetramethylene succinate-co-tetramethylene adipate) and poly(tetramethylene succinate) through water-soluble products.

Poly(tetramethylene succinate-co-tetramethylene adipate) (PBSA) and poly(tetramethylenesuccinate) (PBS) were hydrolyzed experimentally into water-soluble oligomers and monomers by Chromobacterium extracellular lipase. The oligomers were identified by high-performance liquid chromatography-mass spectrometry and 1H-nuclear magnetic resonance, which indicated that a total of 28 oligomer species were liberated from PBSA, and that 13 of them were identical to the hydrolysates from PBS. Moreover, 20 of the species were polyester-based compounds of monomer units, and the other 8 species were small amounts of diurethane compounds. Bis(hydroxybutyl) succinate (BSB) and bis(hydroxybutyl) hexamethylene dicarbamate (BHB) were the typical oligomers and were chemically synthesized. Biodegradability of BSB and BHB was examined for 28 d in the activated sludge, and analysis of the results of this study indicated that the final conversion rate of constituent carbon to carbon dioxide was estimated at 80 mol% for BSB and 10 mol% for BHB. The remaining amount of carbon in the undegraded BHB was 20 mol%. In the presence of BSB, the biodegradability of BHB was increased by about 1.5 times. The suggestion was made that BSB induced a growth of microorganisms and helped BHB degradation. This is consistent with the observation that the biodegradation of BHB in native soil for 60 d reached > 60%.

Adipates↗
PubMed2001

Epithelial-mesenchymal interactions in wounds: treatment of palmoplantar wounds by nonpalmoplantar pure epidermal sheet grafts.

BACKGROUND: Palms and soles differ from other body sites in terms of clinical and histologic appearance and response to mechanical stress. We previously reported that palmoplantar fibroblasts regulate keratin 9, which is a marker of palms and soles. OBJECTIVE: To treat palmoplantar wounds by using nonpalmoplantar pure epidermal sheets as a graft. DESIGN: Nonrandomized controlled trials. SETTING: University dermatology and plastic surgery services. PATIENTS: Forty-eight patients with palmoplantar wounds caused by burns, trauma, chronic ulcers, and the resection of malignant tumors, such as squamous cell carcinoma and acral lentiginous melanoma. INTERVENTIONS: The patients received nonpalmoplantar pure epidermal sheet grafts (n = 14), nonpalmoplantar donor site skin grafts (n = 17), or palmoplantar donor site skin grafts (n = 17). MAIN OUTCOME MEASURES: Clinical and histologic findings. RESULTS: The pure epidermal sheets were successfully grafted and gradually demonstrated the adoption of a palmoplantar phenotype when reticular dermis of the recipient site remained. The epidermis showed hyperkeratosis and acanthosis by histologic studies and stained positively for keratin 9 in all of the suprabasal keratinocyte layers like palmoplantar-type skin. Pure epidermal sheets were placed on deeper wounds after the wounds had an artificial dermis applied and adopted the palmoplantar phenotype without erosions and ulcerations. Neither nonpalmoplantar split-thickness nor full-thickness skin grafts resulted in a palmoplantar phenotype. CONCLUSIONS: Pure epidermal sheet grafting would be useful for the treatment of palmoplantar wounds as nonpalmoplantar epidermis is much easier to obtain clinically. In addition, secondary procedures are not required to repair the donor site, since this wound is superficial.

Adolescent↗
PubMed2001

[Aortoesophageal fistula due to ruptured thoracic aortic aneurysm: case report of successful primary reconstruction of esophagus].

We report a successful surgical case of 78-year-old woman with aortoesophageal fistula subsequent to the operation for sealed rupture of thoracic aortic aneurysm. She underwent one-stage operation consisted of esophagectomy, transmediastinal interposition of the stomach and esophagogastroanastomosis, to re-establish the gastrointestinal tract. The patient recovered well postoperatively without infection.

Aged↗
PubMed2001

Inverse correlation of thioredoxin expression with estrogen receptor- and p53-dependent tumor growth in breast cancer tissues.

Estrogen receptor (ER) and p53 are important transcription factors in the growth regulation of tumor cells in breast cancer. We reported previously that thioredoxin (TRX) regulates the DNA binding activities of ER and p53 in vitro. The expression of pS-2, a trefoil factor, is also correlated with that of ER. To clarify the regulation mechanism of tumor growth in breast cancer, here we investigated the expression of TRX, ER, pS-2, and p53 and the mitotic index (MI) in 147 breast cancer tissues using immunohistochemical analysis. Of 123 TRX+ cases, ER+ cases (n = 62) showed a higher pS-2 score and lower MI than did ER- cases (n = 61). Furthermore, p53- cases (no mutation in p53; n = 76) also showed a lower MI than did p53+ cases (n = 47). There was no significant correlation between pS-2 and ER, MI and ER, or p53 and MI in the TRX- group. Among the ER+ and p53- cases (ER+/p53- group; n = 61), MI was lower in the TRX+ group (n = 46) than in the TRX- group (n = 15). However, in all other groups (n = 86) with abnormalities in the immunohistochemical expression of either p53 or ER, there was no significant correlation between MI and TRX expression. In the TRX+ and ER +/p53- group (n = 46), histological grading was lower than that in all other groups (n = 101). These findings suggest that TRX expression is linked to the ER- and p53-dependent regulation of tumor growth in breast cancer. In addition, TRX expression in ER+ and p53 intact (wild-type p53+) groups may mean better prognosis than in other conditions.

Adult↗
PubMed2001

[The role of MN/CA IX antigen in carcinogenesis and metastasis of renal cell carcinoma].

MN/CA IX is a carbonic anhydrase (CA) isoenzyme expressed in normal alimentary tract in a tissue-specific manner. This antigen is activated in the majority of renal cell carcinomas (RCC) but not in normal kidney tissues. Although the exact role of CA activity in carcinogenesis and metastasis has not been established, MN/CA9 has been suggested to be implicated in acidification of extracellular milieu surrounding the cancer cells and thus create a microenvironment conductive to tumor growth and spread. Mutations in the von Hippel-Lindau (VHL) gene cause the familial syndrome and are also found in the majority of sporadic RCC. Wild-type VHL was recently described to down-regulate MN/CA9 in RCC cell lines, and the molecular mechanism of MN/CA9 and VHL in renal carcinogenesis is of interest. To investigate the mechanism of MN/CA9 activation in RCC, we examined the methylation status of this gene in RCC cell lines and human tissue samples and found that hypomethylation in the promoter region may play an important role in the expression of MN/CA9. RT-PCR analysis of blood samples from RCC patients revealed the presence of circulating MN-positive cells in the blood. This antigen may be a potential therapeutic target as well as diagnostic marker for RCC. Therefore, we are currently investigating whether or not MN/CA IX peptide could be an appropriate molecule for use antigen specific immunotherapy on RCC patients.

Antigens, Neoplasm↗
PubMed2001

Self-oscillating polymer chain in a laser field.

We have investigated the dynamical behaviour of the rhythmic conformational change between the folded compact state and the unfolded state in a single polymer chain under thermodynamically open conditions. It is shown that the spontaneous rhythmic change in the conformation of a single polymer chain (T4DNA, 166 kbp, contour length: 56 microns) is generated using a focused continuous wave (CW) Nd:YAG laser beam (wavelength lambda = 1064 nm), where the focused laser beam plays a dual role, both trapping a polymer chain at the focus and creating a temperature gradient around the focus. Furthermore, the whole process of the rhythmic conformational change: the course of melting, nucleation and growth between the folded and unfolded states has been clarified. The rhythmic change in the conformation is discussed in terms of the limit-cycle oscillation driven by the dissipation of the photon energy.

Bacteriophage T4↗
PubMed2000

Two distinct signaling pathways in hair cycle induction: Stat3-dependent and -independent pathways.

The hair follicle is an epidermal derivative that undergoes cycles of growth, involution, and rest. The hair cycle has well-orchestrated kinetics regulated by interactions between mesenchymal and epithelial cells, although the intracellular signals remain unclear. We previously established keratinocyte-specific Stat3-disrupted mice, by which we demonstrated that signal transducer and activator of transcription 3 (Stat3) is required for wound healing and anagen progression in the hair cycle. Growth factor-dependent migration of Stat3-disrupted keratinocytes was severely impaired, suggesting that not only wound healing but also telogen-to-anagen progression required organized keratinocyte migration in response to mesenchymal stimuli. In the present study, to examine whether Stat3 activation in keratinocytes is a prerequisite for hair cycle progression, we applied methods for experimental anagen induction to Stat3-disrupted mice. It was demonstrated that anagen was successfully induced in Stat3-disrupted as well as wild-type mice by chemical or mechanical stimulation, i.e. , by topical application of phorbol 12-myristate 13-acetate (PMA) or by hair plucking, respectively. This result indicated that anagen in these methods occurred in the absence of Stat3. Furthermore, PMA stimulated the migration of Stat3-disrupted keratinocytes in vitro, supporting a hypothesis that the protein kinase C (PKC) and Stat3 pathways occur independently in the postnatal anagen induction. Both Stat3-dependent and -independent migration of keratinocytes was inhibited by a phosphoinositide 3-kinase (PI3K) inhibitor, wortmannin. Therefore, we infer that entry into anagen is mediated by at least two distinct signaling pathways: Stat3-dependent pathway for spontaneous hair cycling and Stat3-independent (probably PKC-dependent) pathway for exogenously induced hair cycling, whereas both pathways require PI3K activation.

Animals↗
PubMed2000

The postmitotic growth suppressor necdin interacts with a calcium-binding protein (NEFA) in neuronal cytoplasm.

Necdin, a growth suppressor expressed predominantly in postmitotic neurons, interacts with viral oncoproteins and cellular transcription factors E2F1 and p53. In search of other cellular targets of necdin, we screened cDNA libraries from neurally differentiated murine embryonal carcinoma P19 cells and adult rat brain by the yeast two-hybrid assay. We isolated cDNAs encoding partial sequences of mouse NEFA and rat nucleobindin (CALNUC), which are Ca(2+)-binding proteins possessing similar domain structures. Necdin interacted with NEFA via a domain encompassing two EF hand motifs, which had Ca(2+) binding activity as determined by (45)Ca(2+) overlay. NEFA was widely distributed in mouse organs, whereas necdin was expressed predominantly in the brain and skeletal muscle. In mouse brain in vivo, NEFA was localized in neuronal perikarya and dendrites. By immunoelectron microscopy, NEFA was localized to the cisternae of the endoplasmic reticulum and nuclear envelope in brain neurons. NEFA-green fluorescent protein (GFP) fusion protein expressed in neuroblastoma N1E-115 cells was retained in the cytoplasm and partly secreted into the culture medium. Necdin enhanced the cytoplasmic retention of NEFA-GFP and potentiated the effect of NEFA-GFP on caffeine-evoked elevation of cytosolic Ca(2+) levels. Thus, necdin and NEFA might be involved in Ca(2+) homeostasis in neuronal cytoplasm.

Animals↗
PubMed2000

Abnormal expression of BRCA1 and BRCA1-interactive DNA-repair proteins in breast carcinomas.

Breast cancer is one of the most common malignancies among women. The molecular mechanisms involved in breast carcinogenesis, however, remain to be elucidated. Although somatic mutation of BRCA1 is rare, BRCA1 protein expression is reduced in about 30% of sporadic breast carcinomas (Yoshikawa et al., Clin. Cancer Res., 5:1249-1261, 1999), indicating its possible involvement even in sporadic breast carcinogenesis. Among the BRCA1-interactive proteins are hRAD51 (a human homologue of Escherichia coli rec A protein), BARD1 (BRCA1-associated RING domain 1) and p53, all of which are involved in DNA repair. We have analyzed the expression patterns of the hRAD51, BARD1 and p53 proteins in five breast cancer cell lines, including a BRCA1-deficient cell line, and in 179 breast cancer tissue samples from Japanese women, including 113 sporadic, 47 hereditary (i.e., BRCA1 status unknown), and 19 BRCA1-associated cases. Of the 179 breast carcinomas, fifty-four (30%) exhibited reduced hRAD51 expression, and sixty-two (35%) exhibited p53 overexpression. On the other hand, reduced expression level of BARD1, and of hMSH2 and hMLH1, which are components of DNA mismatch-repair pathway and are involved in colorectal carcinogenesis, was observed respectively in only 10 (6%), 8 (5%) and 3 (2%) cases. The overall frequency of sporadic breast carcinomas with abnormal expression of either BRCA1 or the BRCA1-interactive proteins was 67% (76/113). These results indicate that there may be an important role for the BRCA1-associated DNA-repair pathway, not only in BRCA1-associated breast carcinomas, but also in sporadic breast carcinomas.

Adaptor Proteins, Signal Transducing↗