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Biomedical subjects

T Miki

Publications and source records attributed to T Miki.

At least 235 records · Page 13Linked to original sources
PubMed1999

[Results of chemotherapy and salvage surgery for advanced testicular cancer].

Since 1980, 73 patients with advanced testicular cancer have been treated with chemotherapy and 43 patients received post-chemotherapy (salvage) surgery. The median age of all patients was 31 years old, ranging from 17 to 63 years. The histology of the primary testicular tumor was pure seminoma in 23 patients and non-seminoma in 50 patients. According to the Japan Urological Association classification, 38 patients were classified as stage II and 35 patients as stage III. As first-line chamotherapy, 52 patients were treated with PVB regimen (cisplatin, vinblastin, bleomycin), 16 patients with PEB (cisplatin, etoposide, bleomycin) and 5 patients with VAB-6 (vinblastine, actinomycin-D, bleomycin, cisplatin, cyclophosphamide). Thirty (41%) of the 73 patients achieved a complete response (CR) with chemotherapy alone and 63 (86%) achieved no evidence of disease (NED) with salvage treatment. As second-line chemotherapy, 16 patients were treated with PE (cisplatin, etoposide), or VIP (etoposide, ifosfamide, cisplatin) or VeIP (vinblastine, ifosfamide, cisplatin). One of the 16 patients achieved CR and 11 (69%) patients achieved NED. As salvage surgery, retroperitoneal lymphnode dissection (RPLND) was performed in 22 patients, RPLND with thoracotomy in 7 cases and thoracotomy alone in 4 cases. Necrosis was found in surgical specimens of 24 (56%) patients, mature teratoma in 6 (14%) and residual cancer in 13 (30%). Ninety-six percent and 100% of the patients with necrosis and mature teratoma survived with NED, respectively, but only 54% of the patients with residual carcinoma survived despite further treatment. Residual cancer was still found in 8 of the 32 (25%) marker normalized cases. Residual cancer could not reliably be predicted or discriminated from necrosis or mature teratoma by the prognostic criteria. Therefore, salvage surgery remains essential in the treatment of advanced testicular cancer.

Adolescent↗
PubMed1999

[High-dose chemotherapy with peripheral blood stem cell autotransplantation for patients with poor-risk testicular germ cell tumors--pilot study of the Japan Blood Cell Transplantation Study Group].

The efficacy and toxicity of a single cycle of high-dose chemotherapy with peripheral blood stem cell autotransplantation (PBSCT) in patients with poor-risk testicular germ cell tumors (GCT) enrolled in the Japan Blood Cell Transplantation Study Group was investigated. Previously untreated poor-risk testicular GCT patients were treated with BEP therapy (cisplatin, etoposide and bleomycin) with or without high-dose chemotherapy (carboplatin, etoposide and ifosphamide) followed by PBSCT. Patients were qualified for a change to high-dose chemotherapy if elevated serum tumor markers (human chorionic gonadotropin-beta, alpha-fetoprotein and lactate dehydrogenase) was observed after 3 cycles of BEP therapy. Eighteen patients were treated with BEP therapy alone and 16 with BEP and high-dose chemotherapy. At the completion of high-dose chemotherapy, all tumor markers had returned to normal in 6 patients. Among them, 1 had only teratoma found at resection and 5 had carcinoma resected. Nine patients who had persistent elevation of any tumor marker were treated with high-dose chemotherapy or another anticancer drug. Thirteen are alive (81%) and 9 (56%) are continuously disease-free at a median follow up of 11 months. The median time from PBSCT to a granulocyte count > 500/microL was 9.5 days and to a platelet count > 50,000/microL was 13 days.

Adolescent↗
PubMed1999

[The salvage chemotherapy for refractory testicular cancer with novel anticancer agents].

Despite the generally high cure rate in patients with metastatic testicular cancer, 20% to 30% of treated patients will become candidates for salvage chemotherapy. We reviewed the recent salvage chemotherapy trials of refractory diseases. CPT-11 is a new derivative of camptothecin and has activity in a variety of solid tumors. We evaluated the antitumor effect of combination chemotherapy using CDDP and CPT-11 against refractory testicular cancer. Fourteen patients who failed to achieve complete remission with salvage chemotherapy were treated with combination chemotherapy with CPT-11 and CDDP or 254-S (nedaplatin) as third line chemotherapy. Six patients remain alive and disease-free and 5 patients died of disease. The combination of CPT-11 and either CDDP or nedaplatin was significantly more effective than other salvage therapy regimens such as VIP. Paclitaxel, ifosfamide, etoposide regimens were also effective in patients with refractory testicular tumors. We concluded that these combination regimens demonstrated significant activity against refractory testicular tumor and further investigation is warranted.

Adult↗
PubMed1999

Effect of saliva on the growth of Helicobacter pylori.

The effect of saliva mixed in culture media from young healthy volunteers on the growth of Helicobacter pylori (H. pylori) was investigated. Saliva was centrifuged at 15,000 rpm for 10 min and the supernatant was mixed with the reference strain of standard H. pylori which was suspended in sterilized physiological saline. The mixture was inoculated onto agar plate and incubated for 3 days. The numbers of colonies were counted. Saliva from a young male volunteer stimulated the growth of H. pylori significantly compared with the control. This result indicates that there may be such individuals who have saliva increasing the growth of H. pylori. But this is the preliminary report and more studies are needed to know what factors in saliva may affect the growth of H. pylori.

Adult↗
PubMed1999

WT1 Gene Expression in Human Testicular Germ-Cell Tumors.

The Wilms' tumor 1 gene (WT1) is a tumor suppressor gene whose alterations are linked to the genesis of Wilms¹ tumor. The gene is expressed in the urogenital organs and plays a key role in their development. Recent studies have shown that the WT1 gene product acts as a growth promoter of human leukemic cells. Because WT1 has been reported to be important in testicular development, we have investigated WT1 messenger RNA (mRNA) expression in testicular germ-cell tumors. Quantitative reverse transcription­polymerase chain reaction (RT-PCR) was used to examine the levels of WT1 mRNA in 34 patients with testicular germ-cell tumor, including 25 low-stage and 9 high-stage tumors. There were 23 seminomas and 11 nonseminomas. The WT1 mRNA was highly expressed in 6 of 9 high-stage lesions (67%) but only 5 of 25 low-stage cases (20%). A significant correlation was observed between the extent of WT1 mRNA expression and tumor stage (P = 0.017). There was no significant difference in WT1 mRNA expression between seminomas and nonseminomatous tumors. These results suggest that WT1 may be causal for the progression of testicular germ-cell tumors.

Journal Article↗
PubMed1998

Evaluation of pulmonary afferent fibers in the nucleus tractus solitarius: a horseradish peroxidase and c-fos like immunohistochemical study in the rat.

Wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected into the rat lung parenchyma, just beneath the lateral surface of the left upper lobe, in order to demonstrate the pulmonary afferents. This injection resulted in heavy accumulation of labeled fibers in the medial nucleus tractus solitarius (NTS). The labeling in the medial NTS was divided into the ventral and dorsal parts at the level around the obex. Some labeling was found in the commissural and ventrolateral NTS. Further confirmation of the central distribution of these pulmonary afferent fibers was made by the expression of fos-like immunoreactivity (FOS-LI) induced by injection of formalin into the lung. It is concluded that afferents of lung parenchyma terminating predominantly in the medial NTS might come from alveoli and terminal bronchioles, because WGA-HRP and formalin injected into the lung are considered to be confined to the terminal areas of the respiratory tract.

Animals↗
PubMed1998

Rho-regulated signals induce apoptosis in vitro and in vivo by a p53-independent, but Bcl2 dependent pathway.

Rho proteins are a branch of GTPases that belongs to the Ras superfamily which are critical elements of signal transduction pathways leading to a variety of cellular responses. This family of small GTPases has been involved in diverse biological functions such as cytoskeleton organization, cell growth and transformation, cell motility, migration, metastasis, and responses to stress. We report that several human Rho proteins including Rho A, Rho C and Rac 1, are capable of inducing apoptosis in different cell systems like murine NIH3T3 fibroblasts and the human erythroleukemia K562 cell line. Since K562 cells are devoid of p53, apoptosis induced by Rho in this system is independent of p53. Rho-dependent apoptosis is mediated by the generation of ceramides, and it is drastically inhibited by ectopic expression of Bcl2, both under in vitro and in vivo conditions. Furthermore, the human oncogenes vav and ost that have been shown to function as guanine exchange factors for Rho proteins, were also able to induce apoptosis under similar conditions. Finally, we also report that the levels of endogenous Rho proteins are increased when U937 myeloid leukemia cells are exposed to apoptosis-inducing conditions such as TNF alpha treatment. Furthermore, TNF alpha-induced apoptosis in these cells is inhibited by expression of a dominant negative mutant of Rac 1 but it is not affected by a similar mutant of Rho A. These results suggest that Rho proteins play an important role in the physiological regulation of the apoptotic response to stress-inducing agents.

3T3 Cells↗
PubMed1998

DNA damage activates p53 through a phosphorylation-acetylation cascade.

Activation of p53-mediated transcription is a critical cellular response to DNA damage. p53 stability and site-specific DNA-binding activity and, therefore, transcriptional activity, are modulated by post-translational modifications including phosphorylation and acetylation. Here we show that p53 is acetylated in vitro at separate sites by two different histone acetyltransferases (HATs), the coactivators p300 and PCAF. p300 acetylates Lys-382 in the carboxy-terminal region of p53, whereas PCAF acetylates Lys-320 in the nuclear localization signal. Acetylations at either site enhance sequence-specific DNA binding. Using a polyclonal antisera specific for p53 that is phosphorylated or acetylated at specific residues, we show that Lys-382 of human p53 becomes acetylated and Ser-33 and Ser-37 become phosphorylated in vivo after exposing cells to UV light or ionizing radiation. In vitro, amino-terminal p53 peptides phosphorylated at Ser-33 and/or at Ser-37 differentially inhibited p53 acetylation by each HAT. These results suggest that DNA damage enhances p53 activity as a transcription factor in part through carboxy-terminal acetylation that, in turn, is directed by amino-terminal phosphorylation.

Acetylation↗
PubMed1998

Defective insulin secretion and enhanced insulin action in KATP channel-deficient mice.

ATP-sensitive K+ (KATP) channels regulate many cellular functions by linking cell metabolism to membrane potential. We have generated KATP channel-deficient mice by genetic disruption of Kir6.2, which forms the K+ ion-selective pore of the channel. The homozygous mice (Kir6.2(-/-)) lack KATP channel activity. Although the resting membrane potential and basal intracellular calcium concentrations ([Ca2+]i) of pancreatic beta cells in Kir6.2(-/-) are significantly higher than those in control mice (Kir6.2(+/+)), neither glucose at high concentrations nor the sulfonylurea tolbutamide elicits a rise in [Ca2+]i, and no significant insulin secretion in response to either glucose or tolbutamide is found in Kir6.2(-/-), as assessed by perifusion and batch incubation of pancreatic islets. Despite the defect in glucose-induced insulin secretion, Kir6.2(-/-) show only mild impairment in glucose tolerance. The glucose-lowering effect of insulin, as assessed by an insulin tolerance test, is increased significantly in Kir6.2(-/-), which could protect Kir6.2(-/-) from developing hyperglycemia. Our data indicate that the KATP channel in pancreatic beta cells is a key regulator of both glucose- and sulfonylurea-induced insulin secretion and suggest also that the KATP channel in skeletal muscle might be involved in insulin action.

Animals↗
PubMed1998

Site-directed mutational analysis for the ATP binding of DnaA protein. Functions of two conserved amino acids (Lys-178 and Asp-235) located in the ATP-binding domain of DnaA protein in vitro and in vivo.

DnaA protein, the initiator of chromosomal DNA replication in Escherichia coli, is activated by binding to ATP in vitro. We introduced site-directed mutations into two amino acids of the protein conserved among various ATP-binding proteins and examined functions of the mutated DnaA proteins, in vitro and in vivo. Both mutated DnaA proteins (Lys-178 --> Ile or Asp-235 --> Asn) lost the affinity for both ATP and ADP but did maintain binding activity for oriC. Specific activities in an oriC DNA replication system in vitro were less than one-tenth those of the wild-type protein. Assay of the generation of oriC sites sensitive to P1 nuclease, using the mutated DnaA proteins, revealed a defect in induction of the duplex opening at oriC. On the other hand, expression of each mutated DnaA protein in the temperature-sensitive dnaA46 mutant did not complement the temperature sensitivity. We suggest that Lys-178 and Asp-235 of DnaA protein are essential for the activity needed to initiate oriC DNA replication in vitro and in vivo and that ATP binding to DnaA protein is required for DNA replication-related functions.

Adenosine Triphosphate↗
PubMed1998

Stage and organ dependent effects of 1-O-hexyl-2,3,5-trimethylhydroquinone, ascorbic acid derivatives, n-heptadecane-8-10-dione and phenylethyl isothiocyanate in a rat multiorgan carcinogenesis model.

The effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), phenylethylisothiocyanate (PEITC), 3-O-ethylascorbic acid, 3-O-dodecylcarbomethylascorbic acid and n-heptadecane-8, 10-dione were analyzed in a rat multiorgan carcinogenesis model. Groups of 15 animals were given a single intraperitoneal (i.p.) injection of diethylnitrosamine and 4 i.p. injections of N-methylnitrosourea as well as N-butyl-N-(4-hydroxybutyl) nitrosamine in the drinking water during the first 2 weeks. Then 4 subcutaneous (s.c.) injections of dimethylhydrazine and 2,2'-dihydroxy-di-n-propylnitrosamine were given in the drinking water over the next 2 weeks for initiation. Test compounds were administered during the initiation or post-initiation periods. The dietary dose was 1% except for n-heptadecane-8, 10-dione and PEITC (0.1%). Complete autopsy was performed at the end of experimental week 28. All 5 compounds reduced the number of lung hyperplasia, particularly PEITC when given during the initiation period. In addition, HTHQ lowered the incidence of esophageal hyperplasia in the initiation period, and of small and large intestinal adenomas in the post-initiation period. However, it also enhanced the development of hyperplasia and papilloma in the forestomach and tongue. PEITC lowered the induction of esophageal hyperplasia, kidney atypical tubules and liver glutathione S-transferase placental form (GST-P)-positive foci when given during the initiation period but enhanced the development of liver GST-P positive foci and urinary bladder tumors in the post-initiation period. Moreover, it induced hyperplasia of the urinary bladder. Our results indicate minor adverse effects for HTHQ in the forestomach and tongue, and demonstrate that PEITC, which inhibits carcinogenesis at the initiation stage in several organs, also exhibits promotion potential in liver and urinary bladder in the post-initiation stage under the present experimental conditions.

Animals↗
PubMed1998

A method for motion compensation of a moving nematode Caenorhabditis elegans and its application to frequency analysis of pharyngeal pulsation.

A new sequential image processing method for motion compensation of a moving object with stringy shape has been developed for estimating the pharyngeal pulsation of the nematode Caenorhabditis elegans under several environmental conditions. The method is based on the pixel data transfer on a new image frame while changing the boundary shape and the position but preserving the conformation of the inner structure of an object. All digitized image frames of C. elegans were first converted to motion-compensated images to arrange the pulsation site in the same region of the every transformed frame. The pulsation site was then automatically detected by determining the pixels where the temporal brightness variation was much larger than that of the other pixels. Finally, the pulsation frequency was determined by the Fourier analysis. The validity of our method has been confirmed by analyzing various test data, and the method has been applied for detecting the pharyngeal pulsation frequencies of C. elegans on some environmental conditions, i.e. feed bacteria-free/rich, doping of nerve inactivating ethyl-alcohol and nerve stimulant neurochemical substance of serotonin. The motion compensation method automatically provided reasonable pulsation frequencies which were found to be comparable to those obtained by manual counting. Thus the method is useful for systematic investigations on the variation of pharyngeal pulsation associated with the activity change of the nervous system in environments.

Algorithms↗
PubMed1998

Importance of glucose-6-phosphate dehydrogenase in the adaptive response to hydrogen peroxide in Saccharomyces cerevisiae.

Glucose-6-phosphate dehydrogenase (G6PDH)-deficient cells of Saccharomyces cerevisiae showed increased susceptibility and were unable to induce adaptation to oxidative stress. Historically, mainly in human erythrocytes, it has been suggested and accepted that decreased cellular GSH, due to loss of the NADPH-dependent activity of glutathione reductase (GR), is responsible for the increased sensitivity to oxidative stress in G6PDH-deficient cells. In the present study we investigated whether the increased susceptibility and the inability to induce adaptation to H2O2 stress of G6PDH-deficient yeast is caused by incompleteness of glutathione recycling. We constructed G6PDH- and GR-deficient mutants and analysed their adaptive response to H2O2 stress. Although G6PDH-deficient cells contained comparable amounts of GSH and GR activity to wild-type cells, GSSG was not reduced efficiently, and intracellular GSSG levels and the ratio of GSSG to total glutathione (GSSG/tGSH) were higher in G6PDH-deficient cells than in wild-type. On the other hand, GR-deficient cells showed a susceptibility identical with that of wild-type cells and induced adaptation to H2O2 stress, even though the GSSG/tGSH ratio in GR-deficient cells was higher than in G6PDH-deficient cells. These results indicate that incompleteness of glutathione recycling alone is not sufficient to account for the increased sensitivity and inability to induce adaptation to H2O2 stress of G6PDH-deficient yeast cells. In S. cerevisiae, G6PDH appears to play other important roles in the adaptive response to H2O2 stress besides supplying NADPH to the GR reaction.

Adaptation, Physiological↗
PubMed1998

Construction of a yeast expression system with positive selection for gene insertion in the absence of a specific phenotype.

A positive-selection system of cloned inserts in Escherichia coli has been devised using a streptomycin-resistant (Smr) gene and streptomycin-dependent (Smd) E. coli. A vector, pHA394, based on the yeast expression vector pAM82 has the Smr gene, which inactivates streptomycin (Sm) and invalidates the streptomycin dependence, resulting in a very low transformation efficiency. Replacement of the Smr gene by the recombinant vector allows high-frequency transformation. This system was applied to the lysozyme gene. After the yeast secretion signal was fused to the lysozyme gene using an intermediate vector, pHA474, the Smr gene of pHA394 was replaced by the fusion gene, followed by transformation of Smd E. coli. Analysis of the transformants showed that the plasmid gene contained 100% of the lysozyme gene.

Anti-Bacterial Agents↗
PubMed1998

Prognostic factors of renal cell carcinoma: a multivariate analysis.

BACKGROUND AND OBJECTIVES: To establish appropriate therapeutic modalities for renal cell carcinoma (RCC), informations on the factors affecting prognosis of patients are essential. For this purpose, multivariate analysis including a large set of variables is necessary. METHODS: Prognostic significance of 14 clinical factors and 19 histologic factors including counting of silver-stained nucleolar organizer regions (AgNORs) were evaluated in 96 patients. Age of patients ranged from 41 to 85 (median 59) yr with a male to female ratio of 4:1. The tumors were staged based on the TNM classification as follows: 7 in stage I, 58 in stage II, 15 in stage III, and 11 in stage IV. RESULTS: The overall and metastasis-free survival rates in all patients were 80.1% and 72.7%, respectively. Multivariate analysis using Cox's proportional hazards model performed on the factors proved to be significant at the univariate analysis. Univariate analysis revealed four clinical factors including presence of macroscopic hematuria, symptoms such as pain and palpable abdominal mass, anemia, and adjuvant therapy, and nine histologic factors, including AgNOR count, to be significant for survival. Multivariate analysis showed that anemia, pathological stage, and AgNOR count were independent factors for overall survival of patients. The AgNOR count, in particular, is the only predictive factor for metastasis-free survival. CONCLUSIONS: Among various clinicopathological factors, anemia, pathological stage, and AgNOR count are significant prognosticators of RCC. The AgNOR count is also predictive factor for metastasis-free survival.

Adult↗
PubMed1998

Photodynamic effect of a new photosensitizer ATX-S10 on corneal neovascularization.

In order to elucidate the mechanism by which a new photosensitizer ATX-S10 causes the photodynamic effect on neovasculature, we investigated the kinetics and localization of dye accumulation in the neovascular cornea of rats after systemic administration and the development of vascular injury induced by subsequent laser irradiation, compared to those in the normal iris. Under a fluorescence microscope, the neovascular cornea always exhibited more intense fluorescence than the iris between 0.5 and 4 hr after ATX-S10 administration, indicating the preferential deposit of dye in the former tissue. The fluorescence was found inside the vascular lumen at the earliest time period and thereafter in the vascular lining cells, interstitial tissue and infiltrating neutrophils until 6 hr. As observed using light and electron microscopy, laser irradiation performed 2.5 hr after ATX-S10 injection caused extensive vascular thrombosis with endothelial destruction, which persisted for at least 3 days. The proportion of thrombosed vessels at 6 hr after laser irradiation in the neovascular cornea (64+/-5%; n=3) was significantly (P<0.01) higher than that in the normal iris (44+/-8%; n=3). In the non-thrombosed vessels from heparinized rats, in which thrombosis-related ischemic effect was excluded, mitochondrial vacuolation was the pathologic change commonly seen in the endothelial cells, pericytes and neutrophils. Morphometric analysis revealed that the mitochondria of endothelial cells in the corneal new vessels were more severely injured than those in the iris vessels. The present results indicate that ATX-S10 is a potent photosensitizer which induces photodynamic occlusion particularly of new vessels probably due to the preferential biodistribution of dye in the neovascular tissue.

Animals↗
PubMed1998

The PKC activator PMA preconditions rabbit heart in the presence of adenosine receptor blockade: is 5'-nucleotidase important?

While there is good evidence that both protein kinase C (PKC) and adenosine are involved in ischemic preconditioning, their sequence in the intracellular signaling cascade is in dispute. One hypothesis proposes that PKC activation causes release of adenosine which then protects the heart, while the other proposes that adenosine stimulates PKC which in turn causes protection. Accordingly, we studied the effects of specified sequences of pharmacologic triggers and blockers on the infarct-sparing effect of a preconditioning protocol. The combination of the adenosine receptor agonist R(-)N6-(2-phenylisopropyl) adenosine (PIA) and the PKC blocker chelerythrine would be protective only if the first hypothesis were correct. On the other hand, the combination of the adenosine receptor blocker 8-(p-sulfophenyl) theophylline (SPT) and a PKC activator would be protective only if the second hypothesis were correct. Isolated, Krebs-perfused rabbit hearts experienced 30 min of regional ischemia and 2 h of reperfusion. Infarct size was quantitated by triphenyltetrazolium chloride staining. In untreated control hearts, 30.0 +/- 2.7% of the risk zone infarcted. Fifty nmol/l PIA for 20 min starting 10 min prior to ischemia resulted in only 8.4 +/- 1.9% infarction (P<0.01), while the combination of PIA and 5 micromol/l chelerythrine resulted in large infarcts of 27.8 +/- 3.2%. This attenuation of the protective effect continued to be observed even when the PIA infusion was continued to the end of the reperfusion period. Conversely, 0.2 nmol of the PKC activator phorbol 12-myristate 13-acetate (PMA) infused during the 10-min interval prior to ischemia protected the hearts (6.5 +/- 1.3% infarction, P<0.01 v control). And protection persisted when PMA-treated hearts were also exposed to 100 microM SPT for 35 min starting 5 min prior to ischemia (9.5 +/- 1.9% infarction, P<0.01 v control). When PKC activation by the PKC-coupled agonist phenylephrine was continued to the end of ischemia and adenosine blockade was extended throughout the reperfusion period by prolonged infusion of SPT, protection was unaffected. The administration of either SPT or chelerythrine alone did not confer any protection (32.5 +/- 3.3 and 34.0 +/- 3.2% infarction, respectively). Thus, because the combination of PKC activation and adenosine receptor blockade was protective while that of adenosine receptor agonist and PKC blockade was not, adenosine receptors must be upstream of PKC in preconditioning.

Adenosine↗