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Biomedical subjects

N Akiyama

Publications and source records attributed to N Akiyama.

At least 19 recordsLinked to original sources
PubMed1998

Enhancement of gene expression under hypoxic conditions using fragments of the human vascular endothelial growth factor and the erythropoietin genes.

PURPOSE: Selective gene expression in response to tumor hypoxia may provide new avenues, not only for radiotherapy and chemotherapy, but also for gene therapy. In this study, we have assessed the extent of hypoxia responsiveness of various DNA constructs by the luciferase assay to help design vectors suitable for cancer therapy. MATERIALS AND METHODS: Reporter plasmids were constructed with fragments of the human vascular endothelial growth factor (VEGF) and the erythropoietin (Epo) genes encompassing the putative hypoxia-responsive elements (HRE) and the pGL3 promoter vector. Test plasmids and the control pRL-CMV plasmid were cotransfected into tumor cells by the calcium phosphate method. After 6 h hypoxic treatment, the reporter assay was performed. RESULTS: The construct pGL3/VEGF containing the 385 bp fragment of the 5' flanking region in human VEGF gene showed significant increases in luciferase activity in response to hypoxia. The hypoxic/aerobic ratios were about 3-4, and 8-12 for murine and human tumor cells, respectively. Despite the very high degree of conservation among the HREs of mammalian VEGF genes, murine cells showed lower responsiveness than human cells. We next tested the construct pGL3/Epo containing the 150 bp fragment of the 3' flanking region in the Epo gene. Luciferase activity of pGL3/Epo was increased with hypoxia only in human cell lines. The insertion of 5 copies of the 35-bp fragments derived from the VEGF HREs and 32 bp of the E1b minimal promoter resulted in maximal enhancement of hypoxia responsiveness. CONCLUSIONS: The constructs with VEGF or Epo fragments containing HRE may be useful for inducing specific gene expression in hypoxic cells. Especially, the application of multiple copies of the HREs and an E1b minimal promoter appears to have the advantage of great improvement in hypoxia responsiveness.

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↗
PubMed1997

Isolation of a candidate gene, CAB1, for cholesterol transport to mitochondria from the c-ERBB-2 amplicon by a modified cDNA selection method.

An improved cDNA selection method was established to isolate expressed genes efficiently from an amplified chromosome region in human cancer. Biotinylated yeast artificial chromosome DNA containing c-ERBB-2 was hybridized in solution with PCR-amplifiable cDNAs of an esophageal cancer cell line bearing the c-ERBB-2 amplification. After capturing the hybrids on avidin-coated magnetic beads, the cDNAs were amplified by PCR. Four new genes (A39, C51, CAB1, and GRB-7) coamplified with c-ERBB-2 were isolated from the enriched cDNA library. CAB1, GRB-7, and c-ERBB-2 were overexpressed in gastric and esophageal cancer cells in correspondence with the amplification. The deduced amino acid sequence of the CAB1 gene had significant homology to the recently discovered steroidogenic acute regulatory protein, StAR, which plays an essential role in cholesterol transport to mitochondria. It was established that multiple overexpressed genes are frequently present in a single amplicon.

Amino Acid Sequence↗
PubMed1997

Molecular cloning of human GRB-7 co-amplified with CAB1 and c-ERBB-2 in primary gastric cancer.

Many amplified-chromosome regions in human cancers have been identified, while there are only a limited number of reports for amplified genes in a single amplicon. We recently isolated four cDNA clones, A39, B47, C51, and CAB1, from 500 kilobases of yeast artificial chromosome DNA containing the c-ERBB-2 gene. B47 consisted of 615 base pairs and had about 85% homology with the corresponding sequence of mouse Grb-7. We report here the structure of human GRB-7 cDNA, and we report that the amounts of mRNA for c-ERBB-2, CAB1, and GRB-7 were elevated in concordance with the amplification.

Amino Acid Sequence↗
PubMed1997

A novel antiallergic drug epinastine inhibits IL-8 release from human eosinophils.

Eosinophils are believed to be one of the important sources of cytokines at the site of allergic inflammation. A novel antiallergic agent epinastine showed a dose- and time-dependent suppressive effect on IL-8, one of the chemokines for eosinophils, released from eosinophils isolated from atopic diseases. The time-dependent accumulation of IL-8 inhibited by cycloheximide and the evaluation of the IL-8 mRNA levels by reverse transcriptase-polymerase chain reaction suggested that its action occurred in the posttranscriptional processes. It was suggested that epinastine might prevent the autocrine cycle for recruitment of human eosinophils by inhibiting IL-8 release from these cells.

Calcimycin↗
PubMed1997

A comparison of CORVITA and expanded polytetrafluoroethylene vascular grafts implanted in the abdominal aortas of dogs.

The utility of CORVITA vascular grafts, composed of an inner layer of meshed polyurethane fibers and an outer layer of meshed Dacron reinforcement, for replacement of the abdominal aorta was assessed in a canine model and compared with expanded polytetrafluoroethylene (ePTFE) grafts. CORVITA or ePTFE vascular grafts were implanted and left in place for 3 or 6 months. After removal, they were inspected macroscopically and histologically. Microspectrophotometry was used to quantify smooth muscle cells (SMCs), elastin (EL), and collagen (CL) in the media of the native artery. The patency rate of the CORVITA grafts after 6 months was 100%, whereas that of the ePTFE grafts was only 50%. Moreover, stenoses were apparent in all of the ePTFE grafts, but in only 43% of the CORVITA grafts. The intimal thickness at the distal anastomosis was significantly greater at 3 months in the ePTFE grafts (P < 0.01), and there were significantly more SMCs in the host arterial media at the proximal and distal anastomoses in these grafts. Thus, better long-term patency can be expected with CORVITA grafts than with ePTFE grafts. This conferred advantage is most likely attributable to the less pronounced intimal hyperplasia which results from the proliferation of SMCs in the media of the native artery.

Anastomosis, Surgical↗
PubMed1997

Necrotizing Bacillus cereus infection of the meninges without inflammatory reaction in a patient with acute myelogenous leukemia: a case report.

A 64-year-old man in a severely immunocompromised state due to acute myelogenous leukemia died, respirator-unaided, about 10 h after the abrupt onset of coma. An earlier blood culture had yielded Bacillus cereus. The autopsy, performed 2 h after death, demonstrated diffuse subarachnoid hemorrhage without berry aneurysms, and the formalin-fixed brain was tinged with gray-brownish discoloration. The sections of the brain presented a whitish tint of the surface layer of all portion of the cerebral cortices, even those in the sulci. Histological examination of the brain revealed leptomeningeal B. cereus dissemination, and widespread necrosis of the leptomeninges and arachnoid vessels without inflammatory cell reaction. The grossly recognizable whitish surface layer of the cerebral cortex showed overt hyperchromatism, and contained neurons more degenerative than those located in the deeper cortical layer. The total absence of inflammatory reaction may be explained by a combination of the immunocompromised state of the patient and the character of B. cereus infection, which in itself induces little inflammatory reaction. The prominent lesions were confined to the cerebral surface layer and leptomeningeal tissue including the arachnoid vessels, which were all bathed in the cerebrospinal fluid, suggesting that some necrotizing toxins had been secreted into the fluid by the B. cereus. The necrosis of arachnoid vessels is thought to have in turn caused diffuse subarachnoid hemorrhage and marked disturbance of the cerebral blood flow, resulting in the terminal coma.

Bacillus cereus↗
PubMed1997

Pilot study for preoperative administration of l-OHP to patients with advanced scirrhous type gastric cancer.

A new DACH platinum complex, l-OHP, was developed by Kidani as an anticancer agent. A clinical trial took place in Europe which demonstrated its therapeutic efficacy for colorectal cancer. An effective treatment, especially chemotherapy for patients with a advanced scirrhous type gastric cancer, has not yet been established. An in vitro study showed that l-HOP inhibited cell growth in human gastric cancer cell lines. Our pilot study determined the efficacy of preoperative administration of l-OHP, 67 mg/m2 to 100 mg/m2, every 2-3 weeks, for two to three cycles, in five patients with this disease (Stage III and IV) roentogenoscopically and histologically. The platinum concentration in the tissues was also measured. By X-ray examination of the stomach at the time of pre- and post-administration of l-OHP, extension of the lesional gastric wall was observed. Histologically three Grade 2 responses and two Grade 1a responses were obtained according to the criteria presented by Japanese Research Society for Gastric Cancer. The mean platinum concentrations in the lesional tissues were 0.98 ppm and 0.5 ppm in the patients administered l-OHP for three and two cycles respectively. There was no toxicity that prevented surgery. These preliminary results showed the possibility that 1-OHP would be effective for patients with advanced scirrhous type gastric cancer as a neoadjuvant therapy.

Adenocarcinoma, Scirrhous↗
PubMed1997

Fulminant septicemic syndrome of Bacillus cereus in a leukemic patient.

We report a rapidly fatal Bacillus cereus septicemia in a leukemic patient receiving remission-induction therapy. Symptoms resembling food poisoning and fever preceded coma accompanied by neurologic abnormalities. Autopsy revealed necrotizing leptomeningitis with subarachnoid hemorrhage and coagulation necrosis of the liver with bacterial infiltration. These clinicopathologic findings were closely similar to those of reported cases. Because of a rapidly fatal clinical course, suspicion of this syndrome early in the course is important to determine an appropriate treatment. Therefore, we propose that this type of septicemia should be termed as fulminant septicemic syndrome of Bacillus cereus.

Bacillus cereus↗
PubMed1997

Possible involvement of MSX-2 homeoprotein in v-ras-induced transformation.

A truncated MSX-2 homeoprotein was found to induce flat reversion when expressed in v-Ki-ras-transformed NIH3T3 cells. Although the expression of endogenous MSX-2 gene is low in most of the normal adult tissues examined, it is frequently activated in carcinoma-derived cell lines. Likewise, the gene is inactive in untransformed cells but is transcriptionally activated after transformation by v-Ki-ras oncogene, suggesting that the intact MSX-2 may play a positive, rather than suppressive, role in cell transformation. To test this possibility, we isolated a full-length human MSX-2 cDNA and tested its activities in two cell systems: fibroblast and myoblast. In NIH3T3 fibroblasts, although the gene by itself failed to confer a transformed phenotype, antisense MSX-2 cDNA as well as truncated MSX-2 cDNA interfered with the transforming activities of both v-Ki-ras and v-raf oncogene. In C2C12 myoblasts, MSX-2 was found to suppress MyoD gene expression, as do activated ras oncogenes, under certain culture conditions, and truncated MSX-2 cDNA was found to inhibit the activities of both MSX-2 and ras in this system as well. Our findings not only suggest that the truncated version MSX-2 may act as a dominant suppressor of intact MSX-2 but also raise the possibility that MSX-2 gene may be an important downstream target for the Ras signaling pathways.

3T3 Cells↗
PubMed1996

Characterization of mutations induced by 300 and 320 nm UV radiation in a rat fibroblast cell line.

The cytotoxic and mutagenic activities of monochromatic ultraviolet light (UV) at four wavelengths (254, 290, 300 and 320 nm) were determined using a rat fibroblast cell line CREF stably infected with a retroviral vector carrying the neo and HSV-tk markers. In this system, mutations can be positively detected as acyclovir-resistant colonies. Although the action spectra for these activities closely fit some of the previously reported spectra for photochemical DNA modifications, erythema, cell killing and mouse skin carcinogenesis, they diverge at 320 nm from the absorption spectrum for DNA and the action spectrum for bacterial inactivation and mutagenesis. Structural comparison of the HSV-tk mutants detected after irradiation with 300 and 320 nm UV revealed (1) CC dimers and C oligomers as predominant targets at both wavelengths; (2) increased incidence of relatively large deletions at 300 nm; and (3) greatly increased frequency of tandem double mutations at both wavelengths and of clustered multiple mutations at 320 nm. These results suggest the involvement of distinct mechanisms specifically operating, or becoming evident, in UV-mediated mutagenesis at these different wavelengths in mammalian cells.

Acyclovir↗
PubMed1996

Characterization of a human MSX-2 cDNA and its fragment isolated as a transformation suppressor gene against v-Ki-ras oncogene.

A cDNA (termed CT124) encoding a carboxyl-terminal fragment of the human homeobox protein MSX-2 was found to induce flat reversion when expressed in v-Ki-ras-transformed NIH3T3 cells. Although the expression of endogenous MSX-2 gene is low in most of the normal adult tissues examined, it is frequently activated in carcinoma-derived cell lines. Likewise, the gene is inactive in NIH3T3 cells but is transcriptionally activated after transformation by v-Ki-ras oncogene, suggesting that the intact MSX-2 may play a positive, rather than suppressive, role in cell transformation. To test this possibility, we isolated a near full-length human MSX-2 cDNA and tested its activities in two cell systems, i.e. fibroblast and myoblast. In NIH3T3 fibroblasts, although the gene by itself failed to confer a transformed phenotype, antisense MSX-2 cDNA as well as truncated CT124 cDNA interfered with the transforming activities of v-Ki-ras oncogene. In C2C12 myoblasts, MSX-2 was found to suppress MyoD gene expression, as do activated ras oncogenes, under certain culture conditions, and CT124 was found to inhibit the activities of both MSX-2 and ras in this system as well. Our findings not only suggest that CT124 may act as a dominant suppressor of MSX-2 but also raise the possibility that MSX-2 gene may be an important downstream target for the Ras signaling pathways.

3T3 Cells↗
PubMed1996

Changes in angiographic features and the ankle/brachial pressure index of femorodistal arterial bypass grafts during knee flexion.

Systolic ankle pressure was measured in limbs in the extended and 90 degrees-flexed positions in three groups of patients who had undergone below-knee femorodistal arterial bypass. Group 1 consisted of eight limbs in seven patients who had received an autologous saphenous vein (ASV) graft; group 2 consisted of seven limbs in seven patients who had received a ringed expanded polytetrafluorethylene (ePTFE) graft; and group 3 consisted of five limbs in five patients who had received a reinforced biosynthetic borine collagen vascular (Omniflow) graft. Intravenous digital subtraction angiography was performed within 3 months of implantation. The ankle/brachial index (ABI) was significantly lower when the knee was flexed than when it was extended in group 1 and 3, but not in group 2. The ABI flexion in group 1 was similar to that in group 2. Morphologic changes such as kinking were demonstrated angiographically in groups 1 and 3. Given that the ABIs in groups 1 and 2 were similar with the knee flexed, despite the morphologic changes in group 1, we concluded that saphenous vein and ringed ePTFE grafts are more durable when subjected to acute knee flexion than Omniflow grafts. Thus, as graft failure is unlikely to result from kinking as a result of knee flexion alone, further clinical studies are required to elucidate the precise causes of graft failure.

Aged↗
PubMed1996

Successful management of a giant spinal arteriovenous malformation with multiple communications between primitive arterial and venous structures by embolization: report of a case.

A 47-year-old woman was admitted to our hospital with a giant spinal arteriovenous malformation (AVM) causing heart failure and thoracic myelopathy. Angiography revealed that the spinal AVM had multiple feeding vessels branching from the 5th through 12th intercostal arteries. The drainage vein flowed to the azygos vein and superior vena cava. The AVM destroyed the 7th thoracic vertebra. The cardiac output was 16.7l/min and the shunt ratio was 64% before treatment. Embolization with cyanoacrylate was performed because the operation was considered to be associated with a significant risk of paraplegia and organ ischemia. The cardiac output decreased to 11.6l/min and the shunt ratio was reduced to 32%. After embolization the patient demonstrated no symptoms of either heart failure or sensory deficits. During embolization, provocative tests using sodium amytal and lidocaine with magnetic stimulation were also performed. The above findings suggest that provocative tests and magnetic stimulation are useful to predict paraplegia, which could result from embolization while, in addition, embolization is considered to be a useful treatment for multiple shunt and nidus in this region.

Angiography↗
PubMed1996

An orally active antitumor cyclohexanediamine-Pt(IV) complex: trans,cis,cis-bis(n-valerato)(oxalato)(1R,2R-cyclohexane diamine)Pt(IV).

In order to develop orally active antitumor platinum complexes, several cyclohexanediamine-Pt(IV) complexes of a general formula trans,cis,cis-[Pt(IV) (OCOCnHn+1)2 (oxalato)(1R,2R-cyclohexanediamine)] were synthesized by derivatizing oxaliplatin [Pt(II)(oxalato)(1R,2R-cyclohexanediamine), I-OHP], which is a potent antitumor cyclohexanediamine-Pt(II) complex we have prepared and now undergoing clinical trials. The I-OHP derivatives were found to be stable, lipophilic and reduced to yield I-OHP, an active species, quantitatively by ascorbate in vitro. All the derivatives were antitumor active against mouse lymphocytic leukemia L1210 when given i.p. In particular, trans-bis-valerato-oxalato-1R,2R-dach-Pt(IV), C5-OHP, showed markedly high activity. C5-OHP also exhibited significant antitumor activity against L1210 when orally administered. C5-OHP was considered to be a suitable candidate for the oral cancer chemotherapy agent to be developed.

Animals↗
PubMed1996

Effect of E5510 on anastomotic intimal hyperplasia and platelet aggregation in dogs.

We examined the effect of an antiplatelet agent, E5510, which inhibits both platelet aggregation and release of platelet-derived growth factor (PDGF), on anastomotic intimal hyperplasia and platelet aggregation. Twenty Beagle dogs underwent infrarenal aortic reconstruction with an expanded polytetrafluoroethylene (ePTFE) graft 5 mm in diameter and 3 cm long. The dogs were divided into three groups: placebo (control group, 7 dogs), E5510 1 mg/day (1-mg group, 6 dogs), and E5510 4 mg/day (4-mg group, 7 dogs). E5510 was administered orally 2 h before operation and once daily for 3 months after operation. Grafts were harvested 3 months after operation. All 13 grafts in the treated groups remained patent without evidence of intimal hyperplasia, whereas only 4 of 7 grafts (57%) remained patent in the control group, including 1 graft with > 50% stenosis. Three occluded grafts showed severe intimal hyperplasia at the anastomoses. The platelet aggregation ratio (PAR) with collagen (100 micrograms/ml) before drug administration at 3 months in the 4-mg group was significantly lower than that in the control and 1-mg groups. PAR after drug administration at 3 months in the 1- and 4-mg groups was significantly lower than that in the control group. Intimal thickness at the distal anastomosis was 817 +/- 190 microns in the control group, 240 +/- 80 microns in the 1-mg group, and 197 +/- 28 microns in the 4-mg group. Intimal thickness in the control group was significantly greater than that in the 1- and 4-mg groups. Smooth muscle cell (SMC) values in the intima at the distal anastomosis were 65.6 +/- 4.4% extinction (%E) in the control group, 47.6 +/- 3.4%E in the 1-mg group, and 51.3 +/- 3.5%E in the 4-mg group. SMC value in the control group was significantly greater than that in the 1- and 4-mg groups. E5510 inhibited PAR and reduced the degree of anastomotic intimal hyperplasia.

Anastomosis, Surgical↗
PubMed1996

[Peripheral nerve myelin antigen-specific T cells in human].

In recent years, anti-myelin glycolipid antibodies have been reported to be specific for acute inflammatory demyelinating polyneuritis (AIDP) so the involvement of autoimmune mechanism by such autoantibodies was strongly suggested as a cause of AIDP. However, the cellular immunity of AIDP has been seldom reported yet. To examine the T cell response to peripheral nerve antigens in human, we tried to establish T cell lines reactive to peripheral myelin antigens. P0 56-71, P0 180-199 and P2 59-78 peptides from human peripheral blood of controls and patients with inflammatory demyelinating polyneuritis. Frequencies of T cells reactive with P0 56-71, P0 180-199 and P2 59-78 peptides in five controls were (0.59 +/- 0.81) x 10(-7), (1.53 +/- 0.53) x 10(-7) and (0.11 +/- 0.24) x 10(-7), respectively. Frequency of P0 180-199-reactive T cells in one AIDP patient of acute stage was 3.5 x 10(-7) and approximately 2 times high value of controls. There is no significant association between their frequency and specific MHC class II genotypes in subjects until now. Thus, peripheral myelin antigen-specific T cell lines in particular recognizing P0 180-199 were established from the majority of controls and polyneuritis patients. These results suggest that the residues of P0 180-199 might be one of T cell epitopes also in human subjects.

Autoantigens↗