[A case of acute emphysematous cholecystitis accompanied with subphrenic abscess].
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Acute Disease↗
Biomedical subjects
T Ohtsubo
Publications and source records attributed to T Ohtsubo.
Identification of human MutY homolog (hMYH) as a repair enzyme for 2-hydroxyadenine in DNA and detection of multiple forms of hMYH located in nuclei and mitochondria.
An enzyme activity introducing an alkali-labile site at 2-hydroxyadenine (2-OH-A) in double-stranded oligonucleotides was detected in nuclear extracts of Jurkat cells. This activity co-eluted with activities toward adenine paired with guanine and 8-oxo-7,8-dihydroguanine (8-oxoG) as a single peak corresponding to a 55 kDa molecular mass on gel filtration chromatography. Further co-purification was then done. Western blotting revealed that these activities also co-purified with a 52 kDa polypeptide which reacted with antibodies against human MYH (anti-hMYH). Recombinant hMYH has essentially similar activities to the partially purified enzyme. Thus, hMYH is likely to possess both adenine and 2-OH-A DNA glycosylase activities. In nuclear extracts from Jurkat cells, a 52 kDa polypeptide was detected with a small amount of 53 kDa polypeptide, while in mitochondrial extracts a 57 kDa polypeptide was detected using anti-hMYH. With amplification of the 5'-regions of the hMYH cDNA, 10 forms of hMYH transcripts were identified and subgrouped into three types, each with a unique 5' sequence. These hMYH transcripts are likely to encode multiple authentic hMYH polypeptides including the 52, 53 and 57 kDa polypeptides detected in Jurkat cells.
Adenine↗
Disruption of mdr1a p-glycoprotein gene results in dysfunction of blood-inner ear barrier in mice.
P-glycoprotein (p-gp), a drug transporter in multidrug-resistant cancer cells, is a transmembrane protein encoded by mdr1a, mdr1b and mdr2 genes in mice. In our previous report, high level p-gp was immunohistochemically detected in capillary endothelial cells of the guinea pig inner ear, supporting a possible role as an extrusion pump in the blood-inner ear barrier (BIB). We investigated the functional involvement of p-gp in the inner ear using mdr1a gene knock-out mice [mdr1a(-/-) mice]. Pharmacokinetic analyses showed that mdr1a(-/-) mice displayed obviously increased accumulations of the p-gp-transported drugs doxorubicin (adriamycin, ADM) and vinblastine in the inner ear tissues compared with those in mdr1a(+/+) mice. Subsequent functional studies using auditory-evoked brainstem responses showed hearing impairment only in mdr1a(-/-) mice after administering these drugs. Furthermore, inhibition of p-gp function by co-administration of cyclosporin A (CsA) with doxorubicin (ADM) in mdr1a(+/+) mice resulted in increased accumulation of ADM in inner ear tissues and hearing impairment similar to that noted in mdr1a(-/-) mice. We conclude that mdr1a p-gp, which acts as an efflux pump in the inner ear, prevents ototoxicity induced by p-gp substrate drugs and contributes to a new functional mechanism in the BIB.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Multicentric hepatocellular carcinomas tend to grow in more damaged segments of the liver.
In 115 patients (68 with liver cirrhosis and 47 without) who underwent curative resection of hepatocellular carcinoma (HCC) caused by hepatitis C virus (HCV)-related chronic liver diseases, we separated the liver into three segments (right, middle, and left) according to the three secondary branches of the Glissonean pedicle. We examined the weight of each resected segment. We also examined the histological findings of the segments in the same liver in 24 other patients with HCV-related chronic liver diseases. The average weight of the segments did not vary significantly in patients without liver cirrhosis. However, the average weight of the segments was significantly different in patients with liver cirrhosis (P = 0.0414) and the weight of the middle segment was lower than that of the other segments. In another group, of 246 patients with curative resection of HCC, of the 90 patients with single nodular HCCs, 45 nodules (50%) were located in the middle segment (P = 0.0004); in the 156 patients with synchronous multicentric HCCs (total, 401 nodules), 220 nodules (54.9%) were located in the middle segment. In 74 of the 156 patients with synchronous multicentric HCCs (47.4%), the HCCs were located in the same segment. The grade, stage of hepatitis, and number of sites of irregular regeneration were significantly different in each segment (P < 0.05), and the middle segment had more advanced hepatitis than the other segments. The rate of occurrence of HCC in the middle segment was higher than that in the other segments. The difference among the segments of the liver in regard to the degree of damage done by hepatitis may be related to the differences in HCC occurrence among the liver segments.
Carcinoma, Hepatocellular↗
Cell cycle progression and apoptosis after irradiation in an acidic environment.
We investigated the effect of an acidic environment on the radiation-induced G2/M arrest and apoptosis using RKO.C human colorectal cancer cells expressing wild-type p53 and RC10.1 cells, a subline of RKO.C cells deficient in p53 as well as p53+/+ MEFs and p53-/- MEFs (mouse embryonic fibroblasts). The cells were irradiated with 4 Gy or 12 Gy of gamma-rays in pH 7.5 medium or pH 6.6 medium. p53 accentuated the progression of cells from radiation-induced G2/M arrest to apoptosis and the pH 6.6 environment suppressed the progression of cells through G2/M-phase to apoptosis after irradiation. Further analysis indicated that the radiation-induced G2/M arrest was due mainly to G2 arrest in both pH 7.5 and pH 6.6. Therefore, it was concluded that p53 enhances, and an acidic environment suppresses, the exit of cells from radiation-induced G2 arrest by altering cyclin B1-Cdc2 kinase activity.
Acids↗
Induction of radioresistance to accelerated carbon-ion beams in recipient cells by nitric oxide excreted from irradiated donor cells of human glioblastoma.
PURPOSE: To investigate whether nitric oxide excreted from cells irradiated with accelerated carbon-ion beams modulates cellular radiosensitivity against irradiation in human glioblastoma A-172 and T98G cells. MATERIALS AND METHODS: Western-blot analysis of inducible nitric oxide synthase, hsp72 and p53, the concentration assay of nitrite in medium and cell survival assay after irradiation with accelerated carbon-ion beams were performed. RESULTS: The accumulation of inducible nitric oxide synthase was caused by accelerated carbon-ion beam irradiation of T98G cells but not of A-172 cells. The accumulation of hsp72 and p53 was observed in A-172 cells after exposure to the conditioned medium of the T98G cells irradiated with accelerated carbon-ion beams, and the accumulation was abolished by the addition of an inhibitor for inducible nitric oxide synthase to the medium. The radiosensitivity of A-172 cells was reduced in the conditioned medium of the T98G cells irradiated with accelerated carbon-ion beams compared with conventional fresh growth medium, and the reduction of radiosensitivity was abolished by the addition of an inducible nitric oxide synthase inhibitor to the conditioned medium. CONCLUSIONS: Nitric oxide excreted from the irradiated donor cells with accelerated carbon-ion beams could modulate the radiosensitivity of recipient cells. These findings indicate the importance of an intercellular signal transduction pathway initiated by nitric oxide in the cellular response to accelerated heavy ions.
Blotting, Western↗
Morphological and functional study of regenerated chorda tympani nerves in humans.
It is still unclear whether the chorda tympani nerves in humans regenerate after being severed during middle ear surgery, although functional studies have demonstrated recovery of taste 1 to 2 years after surgery. To date, 12 cases of regenerated chorda tympani nerves have been found in our series of patients during secondary surgery. The regenerated nerves of 3 cases of the 12 were removed as samples during secondary surgery to detect regenerated myelinated axons. All regenerated nerves were in the submucosal connective tissue layer of the reconstructed eardrum. In the regenerated nerves, myelinated nerve fibers existed in a small fascicle or in connective tissue, but the number of myelinated axons was low compared with that in normal subjects ( 1.752 +/- 78; n = 3), and the distribution was sparse. The total number of regenerated myelinated axons varied from 141 (8.3%) to 979 (55.9%). From a functional study using electrogustometry, incomplete recovery of electrogustation was observed in all 3 cases before secondary surgery, suggesting that chorda tympani nerves actually regenerate in the middle ear and do function.
Adult↗
Nitric oxide is an initiator of intercellular signal transduction for stress response after hyperthermia in mutant p53 cells of human glioblastoma.
Nitric oxide is known to be a multifunctional physiological substance. Recently, it was suggested that nitric oxide is involved in p53-dependent response to many kinds of stress, such as heat shock and changes in cellular metabolism. To verify this hypothesis, we examined the effect of nitric oxide produced endogenously by heat-shocked cells on nonstressed cells using a human glioblastoma cell line, A-172, and its mutant p53 (mp53) transfectant (A-172/mp53). The accumulation of inducible nitric oxide synthase was caused by heat treatment of the mtp53 cells but not of the wild-type p53 (wtp53) cells. The accumulation of heat shock protein 72 (hsp72) and p53 was observed in nontreated mtp53 cells cocultivated with heated mp53 cells, and the accumulation of these proteins was suppressed by the addition of a specific inducible nitric oxide synthase inhibitor, aminoguanidine, to the medium. Furthermore, the accumulation of these proteins was observed in the wtp53 cells after exposure to the conditioned medium by preculture of the heated mp53 cells, and the accumulation was completely blocked by the addition of a specific nitric oxide scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, to the medium. In addition, the accumulation of hsp72 and p53 in the wtp53 cells was induced by the administration of an nitric oxide-generating agent, S-nitroso-N-acetylpenicillamine, to the medium. Finally, the thermosensitivity of the wtp53 cells was reduced in the conditioned medium by preculture of the heated mp53 cells as compared with conventional fresh growth medium. Our finding of the accumulation of hsp72 and p53 in nitric oxide-recipient cells cocultivated with heated nitric oxide-donor cells provides the first evidence for an intercellular signal transduction pathway via nitric oxide as intermediate without cell-to-cell interactions such as gap junctions.
Benzoates↗
Inhibition of N-linked glycosylation by tunicamycin enhances sensitivity to cisplatin in human head-and-neck carcinoma cells.
Tunicamycin (TM), a naturally occurring antibiotic, blocks the first step in the biosynthesis of N-linked oligosaccharides in cells. In this study, we investigated whether changes in N-linked glycosylation affect the sensitivity of head-and-neck carcinoma cell lines to cis-diaminedichloroplatinum(II) (cisplatin) in vitro and in vivo. In vitro treatment of the IMC-3 and KB cell lines with TM significantly decreased the 50% inhibitory concentration (IC50) of cisplatin, as determined by the MTT assay (24.15 to 10.97 microg/ml, p < 0.05). In addition, TM significantly decreased the IC50 of cisplatin against established cisplatin-resistant IMC-3/CR cells (>100 to 14.4 microg/ml, p < 0.05) to levels similar to those against parental IMC-3 cells. TM treatment decreased the number of Con A- and L-PHA-binding sites on the surface of tumor cells but had no effect on the intracellular platinum concentration. Induction of apoptosis in vitro by TM plus cisplatin in combination was increased compared with that by cisplatin alone. Furthermore, in vivo administration of TM plus cisplatin in combination significantly inhibited local tumor growth in the cisplatin-resistant in vivo C3H/He mouse model as compared with the control group (p < 0.05) and increased in vivo apoptosis of tumor cells. Our results suggest that the manipulation of glycosylation by TM in tumor cells might be a useful therapeutic strategy for successful chemotherapy using cisplatin against head-and-neck cancer.
Animals↗
Granulocyte-colony-stimulating factor enhances invasive potential of human head-and-neck-carcinoma cell lines.
Granulocyte-colony-stimulating factor (G-CSF), a hematopoietic cytokine, regulates the proliferation and differentiation of granulocytic progenitor cells and functionally activated mature neutrophils. G-CSF also affects nonhematopoietic tumor cells by the binding of G-CSF to its specific receptor (G-CSFR) on the cells. In this study, we investigated the effect of G-CSF on the invasive potential of head-and-neck carcinoma cells, and explored the intracellular events initiated by the binding of G-CSF in tumor cells. In vitro treatment of head-and-neck-carcinoma cell lines, IMC-2, IMC-3, KB, Ca9-22, SCCKN and SCCTF, with recombinant G-CSF (rG-CSF) significantly augmented their invasive potential in dose- and time-dependent manners. Among these cancer cells, IMC-2, IMC-3, KB and Ca9-22 cells produced little G-CSF, while large amounts of G-CSF were produced by SCCKN and SCCTF cell lines. Anti-G-CSF antibody (Ab) abrogated the rG-CSF-enhanced invasiveness to the control level of that in untreated cancer cell lines. Immunocytochemical staining and Western blotting using anti-G-CSFR monoclonal antibody (MAb) revealed the expression of G-CSFR on head-and-neck-cancer cell lines exhibiting the enhancement of invasive activity by rG-CSF. IMC-2 cells, having the highest invasive ability among the cell lines used, showed augmentation of G-CSFR expression on stimulation with rG-CSF. Furthermore, stimulation of IMC-2 cells with rG-CSF induced rapid activation of tyrosine-phosphorylated JAK1, suggesting that the G-CSF signal may be transduced into the cells through G-CSFR. Moreover, the gelatinolytic activity of IMC-2 cells was enhanced by stimulation of rG-CSF, and the enhanced invasiveness was inhibited on addition of the tissue inhibitors of metalloproteinases (TIMPs). These results suggest that exogenous rG-CSF may increase the risk of metastasis and/or local recurrence in patients with G-CSFR-positive head-and-neck squamous-cell carcinoma, via an invasive mechanism.
Antibodies, Monoclonal↗
Intercellular signaling initiated by nitric oxide produced in heat-shocked human glioblastoma cells.
The accumulation of inducible nitric oxide synthase was caused by heat shock of human glioblastoma T98G cells but not of A-172 cells. The accumulation of hsp72 and p53 was observed in A-172 cells cocultivated with heat-shocked T98G cells, which was suppressed by the addition of aminoguanidine to the medium. The accumulation of these proteins was observed in A-172 cells after exposure to the conditioned medium of heat-shocked T98G cells, which was completely blocked by the addition of 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide to the medium. In addition, the accumulation of these proteins in A-172 cells was induced by the administration of S-nitroso-N-acetylpenicillamine to the medium. Finally, the thermosensitivity of A-172 cells was reduced in the conditioned medium of heat-shocked T98G cells compared with conventional fresh growth medium. Our findings demonstrate that the accumulation of stress-induced proteins and thermoresistance in NO recipient cells cocultivated with heat-shocked NO donor cells is induced through an intercellular signal transduction pathway initiated by NO without cell-to-cell interactions such as gap junctions.
Brain Neoplasms↗
Acidic environment causes apoptosis by increasing caspase activity.
An exposure of HL-60 human promyelocytic leukaemia cells to acidic media with pH 6.2-6.6 caused an up-regulation of Bax protein expression within 2 h, which lasted for longer than 6 h. On the other hand, the apoptosis, as judged from PARP cleavage, DNA fragmentation and flow cytometric determination of cell population with sub-G1 DNA content, occurred after the cells were incubated in the acidic media for longer than 4 h. The PARP cleavage and DNA fragmentation in the cells exposed to an acidic environment could be effectively suppressed by inhibitors specific for ICE or CPP32, indicating that activation of these caspases is an essential step in acidic stress-induced apoptosis. It has been known that Bax is involved in the activation of caspases. Taken together, it appears that acidic stress first up-regulates Bax protein thereby activating caspases followed by PARP cleavage and DNA fragmentation. The observation that inhibition of either ICE or CPP32 could suppress acidic stress-induced apoptosis suggested that ICE activates pro-CPP32, which then cleaves PARP. Flow cytometric analysis indicated that acidic stress-induced apoptosis occurs mainly in G1 cells. The finding in the present study demonstrated that acidic intra-tumour environment may markedly perturb the tumour cell proliferation and tumour growth.
Apoptosis↗
Identification of NRF2, a member of the NF-E2 family of transcription factors, as a substrate for caspase-3(-like) proteases.
Apoptosis is mediated by members of the interleukin-1beta converting enzyme (ICE) family of proteases (caspases), which are activated by diverse stimuli, although the downstream molecular targets of caspases are still poorly understood. Using the modified yeast two-hybrid system, which we recently established to clone genes for caspase substrates, we identified NRF2 as a novel caspase substrate. NRF2 is a member of the NF-E2 family of basic region leucine-zipper transcription factors and has been shown to induce phase II detoxifying enzymes through anti-oxidant response elements. NRF2 was cleaved at two sites by recombinant caspase-3 in vitro as well as in HeLa cells during TNFalpha-mediated apoptosis. Overexpression of the C-terminal cleavage fragment containing the DNA binding and leucine-zipper domains induced apoptosis in HeLa cells. These observations suggest that NRF2 might have some role in the induction of apoptosis after cleavage by caspases.
3T3 Cells↗
Free peroneal skin flap for oropharyngeal reconstruction.
The thicknesses of three dermal flaps, platysma, forearm, and fibula, which are often used for oropharyngeal reconstruction, were measured in 21 subjects using 15 MHz Doppler ultrasonography. The mean (SD) thicknesses were 2.2 (0.3), 3.1 (0.5), and 3.8 (0.6) mm, respectively. The free peroneal skin flap from the leg was used in 14 patients with head and neck cancer. These flaps were successfully transplanted in 13 of 14 patients (93%) with no problems at the donor site. This flap offers many advantages, including its distance from the head and neck, its cosmetic superiority to a forearm flap, it allows two flaps with two cutaneous branches, it is possible to close the donor site primarily without a skin graft, and it has thin subcutaneous tissue. We found that the free peroneal skin flap is particularly useful for oropharyngeal reconstruction.
Adult↗
Expression and differential intracellular localization of two major forms of human 8-oxoguanine DNA glycosylase encoded by alternatively spliced OGG1 mRNAs.
We identified seven alternatively spliced forms of human 8-oxoguanine DNA glycosylase (OGG1) mRNAs, classified into two types based on their last exons (type 1 with exon 7: 1a and 1b; type 2 with exon 8: 2a to 2e). Types 1a and 2a mRNAs are major in human tissues. Seven mRNAs are expected to encode different polypeptides (OGG1-1a to 2e) that share their N terminus with the common mitochondrial targeting signal, and each possesses a unique C terminus. A 36-kDa polypeptide, corresponding to OGG1-1a recognized only by antibodies against the region containing helix-hairpin-helix-PVD motif, was copurified from the nuclear extract with an activity introducing a nick into DNA containing 8-oxoguanine. A 40-kDa polypeptide corresponding to a processed form of OGG1-2a was detected in their mitochondria using antibodies against its C terminus. Electron microscopic immunocytochemistry and subfractionation of the mitochondria revealed that OGG1-2a locates on the inner membrane of mitochondria. Deletion mutant analyses revealed that the unique C terminus of OGG1-2a and its mitochondrial targeting signal are essential for mitochondrial localization and that nuclear localization of OGG1-1a depends on the NLS at its C terminus.
Alternative Splicing↗
Genetic polymorphism of aldehyde dehydrogenase 2 in patients with upper aerodigestive tract cancer.
BACKGROUND: Alcohol consumption is one of the major risk factors of the upper aerodigestive tract (UADT) cancers, and combined cancers are frequently discovered in the patients with UADT cancer. The association between esophageal cancer and alcohol-related metabolizing enzymes is well studied, but only a few examinations about the association between head and neck cancer and the enzymes were performed. METHODS: Fifty-two patients with UADT cancer (head and neck cancer in 25, esophageal cancer in 19, and multiple cancers in 8) were examined in the alcohol habit and in the polymorphisms of aldehyde dehydrogenase 2 (ALDH2) and cytochrome P-4502E1. RESULTS: Patients with multiple cancers had significantly higher ethanol consumption than the other two groups (p < 0.001). The frequency of ALDH2*1/2*2 heterozygote was significantly lower (p = 0.009) in patients with head and neck cancer (5/25) than patients with esophageal cancer (11/19). The allele frequency of P-4502E1 did not show a significant difference between the groups (p = 0.700). CONCLUSIONS: These results demonstrated the difference in the frequency of ALDH2 heterozygote between the patients with esophageal cancer and patients with head and neck cancer.
Aged↗
Synthesis of extremely simplified compounds possessing the key pharmacophore units of taxol, phenylisoserine and oxetane moieties.
Straight chain compounds having a phenylisoserine unit and an oxetane ring at the alpha- and omega- position, respectively as extremely simplified analogues of taxol were prepared. None of these compounds showed promising tubulin inhibitory activity.
Alcohols↗
Prevalence and characterization of hepatitis C virus in hemodialysis patients.
OBJECT: Chronic hepatitis C virus (HCV) infection is common in hemodialysis (HD) patients. In the present study, the prevalence and properties of HCV in HD patients were analyzed. METHODS AND RESULTS: Of 125 HD patients, 34 (27%) were positive for antibody to HCV, and HCV-RNA was detected in 23 (68%) of the 34 patients using reverse transcription polymerase chain reaction. The HCV-RNA sequence analysis did not identify the alterations specific to HD patients with HCV, although one patient had a variant virus containing the deletion of the core gene sequence. When serial changes in the levels of HCV-RNA were evaluated in 15 patients by a branched DNA assay, the values decreased immediately after HD procedure, but returned to the baseline values 2 days after the procedure. CONCLUSION: These results indicate that HCV in HD patients is replication-competent, although a transient reduction in the levels of HCV-RNA occurs during HD.
Adult↗