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Biomedical subjects

K Ishikawa

Publications and source records attributed to K Ishikawa.

At least 37 records · Page 2Linked to original sources
PubMed2005

Selective and efficient culturing of retinal pigment epithelial cells using a feeder layer.

BACKGROUND: The techniques to isolate and purify retinal pigment epithelial (RPE) cells from small piece of autologous tissues are extremely difficult, and it is important to develop an efficient cell culture technique for RPE cells. The purpose of this study was to investigate the effect of 3T3-J2 cells and conditioned medium from 3T3-J2 cells on the proliferation of cultured RPE cells. METHODS: RPE cells from pigmented rabbits and a human RPE-derived cell line, ARPE-19, were used. First, the effects of co-culturing RPE cells with 3T3-J2 cells on the growth of the cells were analyzed. Second, the effects of the conditioned medium from 3T3-J2 cells on the proliferation of both types of cells were investigated. And third, the effects of the conditioned medium on RPE cell culture from a surgically removed choroidal neovascular (CNV) membrane were investigated. RESULTS: The 3T3-J2 cells increased the proliferation of both rabbit RPE cells and ARPE-19 cells. The number of rabbit RPE cells cultured in a mixture of the conditioned medium from 3T3-J2 cells was significantly higher than that in the reported optimal condition, and a similar tendency was observed for ARPE-19 cells. The results from enzyme-linked immunosorbent assay showed the presence of PDGF-AB, VEGF and IGF-I in the conditioned medium. The conditioned medium also promoted selective growth of human RPE cells from CNV. DISCUSSION: The results from this study present the conditions for efficient and selective culture of primary RPE cells.

3T3 Cells↗
PubMed2004

Cryopreservation of immature seeds of Bletilla striata by vitrification.

An efficient protocol was established for the cryopreservation of immature seeds of a terrestrial orchid, Bletilla striata. Immature seeds collected 2-4 months after pollination (MAP) were treated using three different cryogenic procedures: (1) direct plunging into liquid nitrogen, (2) vitrification, and (3) vitrification with preculture. When immature seeds collected 3 MAP and 4 MAP were precultured for 3 days on New Dogashima medium supplemented with 0.3 M sucrose and cryopreserved by vitrification, the survival rate after preservation, as assessed by staining with 2,3,5-triphenyltetrazolium chloride, was 92% and 81%, respectively. Immature seeds thus treated showed no decrease in germination rate relative to untreated immature seeds, and they developed into normal plantlets in vitro.

Cell Culture Techniques↗
PubMed2004

Impaired glucose tolerance is accompanied by decreased insulin sensitivity in tissues of mice implanted with cells that overexpress resistin.

AIM/HYPOTHESIS: Resistin, the expression of which is suppressed by thiazolidinedione treatment in adipocytes, is one of the key molecules for the tight link between adiposity and insulin resistance. Here, we show the in vivo effects of resistin on insulin sensitivity in mature mice using a cell implantation method. METHODS: Resistin cDNA was transfected into 3T3-L1 pre-adipocytes, which were then implanted into subcutaneous areas of nude mice. Metabolic analyses were performed 4 or 6 weeks after implantation. RESULTS: The mice implanted with 3T3-L1 cells overexpressing resistin (R-mice) showed significantly (p<0.05) increased plasma resistin levels. After a glucose load plasma insulin levels were significantly greater in R-mice than in mice implanted with mock-transfected cells (M-mice). The AUC of insulin after glucose loading was positively correlated with circulating resistin levels. Significantly decreased glucose responses after insulin injection were observed in R-mice, compared to M-mice. The insulin-induced phosphorylation level of IRS-1 was significantly lower in muscles of R-mice than M-mice. The expression of TNF-alpha mRNA in intra-peritoneal fat tissues was significantly greater in R-mice than in M-mice, but there was no difference between the two groups with regard to subcutaneous fat tissues. The concentration of TNF-alpha in plasma was positively correlated with resistin levels in R-mice. CONCLUSIONS/INTERPRETATION: Resistin, when actually secreted from cells in mature mice, causes disturbed glucose metabolism, possibly based on decreased insulin sensitivity in muscle. The in vivo effects of resistin on insulin sensitivity might be in part mediated by increased TNF-alpha expression in visceral fat tissues.

3T3 Cells↗
PubMed2004

Photoinduced structural instability of the InP (110)-(1x1) surface.

A scanning tunneling microscopy study reveals the removal of P and In atoms at intrinsic surface sites of InP (110)-(1x1) through an electronic mechanism under ns-laser excitation. Femtosecond nonresonant ionization spectroscopy detects desorption of P and In atoms associated directly with the bond rupture, and shows their translational energies characteristic of electronic bong breaking. The rate of P-atom removal is 4 times higher than that of In-atom removal, revealing a prominent species-dependent effect of structural instability under electronic excitation on semiconductor surfaces.

Journal Article↗
PubMed2004

Laparoscopy-assisted distal gastrectomy for early gastric cancer in obese and nonobese patients.

BACKGROUND: Conventional open gastrectomy has been reported to result in increased morbidity in obese patients. To date, there has been no study evaluating laparoscopic gastrectomy in such patients; therefore, we assessed the short-term results of this procedure in a group of obese patients. METHODS: The study included 99 consecutive patients who underwent laparoscopy-assisted distal gastrectomy (LDG) for the cure of early gastric cancer. The patients were divided into two groups: obese (body mass index [BMI] > or =25.0, n = 16) and nonobese (BMI <25.0, n = 83). Patient characteristics, operative details, and postoperative outcomes were compared and analyzed. RESULTS: Patient characteristics, including age, sex, American Society of Anesthesiologists (ASA) status, and disease stage, were not different between obese and nonobese patients. Operating time was significantly longer in obese patients than in nonobese patients (271 vs 239 min, p < 0.05). However, there was no significant difference between obese and nonobese patients in time to first flatus (3.7 vs 3.3 days), time to solid diet (6.3 vs 5.2 days), length of postoperative hospital stay (18.7 vs 17.9 days), or frequency of major (25% vs 16%) and minor (19% vs 12%) postoperative complications. There were no conversions to conventional open surgery and no perioperative deaths. CONCLUSION: The only difference between our two study groups was that LDG required a longer operating time in obese patients; morbidity and length of hospital stay were not increased. Thus, we believe that LDG is likely to become the treatment of choice for obese patients with early gastric cancer.

Adult↗
PubMed2004

Distal myopathy with rimmed vacuoles (DMRV): new GNE mutations and splice variant.

Study of the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase gene (GNE) revealed that almost all cases of distal myopathy with rimmed vacuoles were caused by GNE mutations. Seven new mutations were identified, including M712T, which is the most common mutation in Jewish hereditary inclusion body myopathy. In addition, a splice-variant characteristic of the skeletal muscle was found, whereas the difference of the expression level between GNE-mutated and -nonmutated patients was not apparent.

Adolescent↗
PubMed2004

Anomalously hindered E2 strength B(E2;2+(1)-->0+) in 16C.

The electric quadrupole transition from the first 2(+) state to the ground 0(+) state in 16C is studied through measurement of the lifetime by a recoil shadow method applied to inelastically scattered radioactive 16C nuclei. The measured mean lifetime is 77+/-14(stat)+/-19(syst) ps. The central value of mean lifetime corresponds to a B(E2;2+(1)-->0(+)) value of 0.63e(2) fm(4), or 0.26 Weisskopf units. The transition strength is found to be anomalously small compared to the empirically predicted value.

Journal Article↗
PubMed2004

Preoperative radio/chemo-radiotherapy in combination with intraoperative radiotherapy for T3-4Nx rectal cancer.

AIMS: To analyse the results of a single institution experience of combined preoperative radio/chemo-radiotherapy and intraoperative electron-radiation therapy (IORT) for locally advanced rectal cancer and to compare the results with surgery alone retrospectively. METHODS: The study cohort comprised 99 patients with clinical T3-4NxM0 adenocarcinoma of the rectum who had received preoperative radio/chemo-radiotherapy, radical surgery, and IORT [Group I]. Until 1998, 67 patients were treated with radiation only [Group Ia], and after 1999, 32 patients were concurrently given tegafur and uracil (UFT) [Group Ib]. 68 patients with clinical T3-4NxM0 rectal cancer were treated with surgery alone [Group II]. RESULTS: The median follow-up was 67 months in Group I and 83 months in Group II. Local recurrence rate was 2% in Group I, which was significantly lower than 16% in Group II (p=0.002) Both disease-free survival and overall survival in Group I were significantly better than those in Group II (p=0.04, p=0.02, respectively). Sphincter preservation was possible in 78% in Group Ib, which was significantly more than 42% in Group Ia (p=0.002). CONCLUSIONS: The combined preoperative radio/chemo-radiotherapy and IORT for clinical T3-4Nx rectal cancer significantly reduces local recurrence and improves prognosis. Combination of preoperative radiotherapy and oral UFT improves the feasibility of sphincter-preservation.

Adenocarcinoma↗
PubMed2004

Basic properties of apatite cement containing spherical tetracalcium phosphate made with plasma melting method.

Apatite cement (AC) can be injected through syringe and forms apatite mass. Therefore, AC is very useful for a minimally invasive surgical operation aimed for the reconstruction of bone defects. However, injectability of current AC is not satisfactory for its clinical use. In this investigation, therefore, spherical tetracalcium phosphate (s-TTCP) was prepared with plasma melting method and its effect on injectability were evaluated as well as other basic properties of AC. We found much better handling property and injectability when we used s-TTCP as a component of AC (s-AC). For example, cement spread area used as an index of consistency of the s-AC paste was 512 mm2 whereas that of ordinary AC with irregular TTCP (i-AC) was 158 mm2 when powder to liquid mixing ratio was 2.5. However, diametral tensile strength of set s-AC (1.4 MPa) was significantly lower than that of set i-AC (10.7 MPa) when the powder to liquid ratio was 4.0. X-ray powder diffraction analysis revealed limited formation of apatite in the case of s-AC. Although there are some drawbacks, we feel the use of spherical particle is very useful to improve the injectability of AC. Therefore, it is important to find suitable method to prepare spherical powder as the component of AC.

Apatites↗
PubMed2004

Hypertension in a patient with Gitelman's syndrome.

Gitelman's syndrome is an autosomal recessive disorder characterized by sodium wasting and hypotension. A middle-aged woman was diagnosed with Gitelman's syndrome because of typical clinical manifestations in the youth and homozygous mutations of 18-base-pair insertion in exon 6 of thiazide-sensitive NaCl-cotransporter gene. It was unusual that she showed hypertension with advancing age. Her serum potassium levels remained low at around 3.5 mEq/l despite potassium supplementation. This case demonstrates that hypertension could result in spite of the extremely decreased sodium reabsorption in Gitelman's syndrome and that essential hypertension is genetically heterogeneous, and abnormality of all genes may not be necessarily required to cause blood pressure rise.

Adult↗
PubMed2004

Prevention of critical telomere shortening by oestradiol in human normal hepatic cultured cells and carbon tetrachloride induced rat liver fibrosis.

BACKGROUND AND AIM: Significant telomere shortening of hepatocytes is associated with replicative senescence and a non-dividing state in chronic liver disease, resulting in end stage liver failure and/or development of hepatocellular carcinoma. To prevent critical telomere shortening in hepatocytes, we have focused on oestrogen dependent transactivation of the human telomerase reverse transcriptase (hTERT) gene as a form of telomerase therapy in chronic liver disease. METHODS: We examined expression of hTERT mRNA and its protein, and telomerase activity (TA) in three human normal hepatic cell lines (Hc-cells, h-Nheps, and WRL-68) before and after treatment with 17beta-oestradiol. The effects of exogenous oestradiol administration were examined in a carbon tetrachloride (CCl(4)) induced model of liver fibrosis in rats. RESULTS: Expression of hTERT mRNA and its protein was upregulated by oestradiol treatment. Telomere length decreased in Hc-cells and h-Nheps with accumulated passages whereas with long term oestradiol exposure it was greater than without oestradiol. The incidence of beta-galactosidase positive cells, indicating a state of senescence, decreased significantly in oestradiol treated cells in comparison with non-treated cells (p<0.05). TA in both male and female rats with CCl(4) induced liver fibrosis was significantly higher with oestradiol administration than without (p<0.05). Long term oestradiol administration markedly rescued the hepatic telomere from extensive shortening in both male and female rats. CONCLUSION: These results suggest that oestradiol acts as a positive modulator of the hTERT gene in the liver. Oestrogen dependent transactivation of the hTERT gene is a new strategy for slowing the progression of chronic liver disease.

Animals↗
PubMed2004

Acute myocardial infarction caused by thrombotic occlusion at a stent site two years after conventional stent implantation.

Two cases of acute myocardial infarction caused by thrombotic occlusion at the conventional stented site two years after stenting are described. Late thrombotic stent occlusion may be caused by atherosclerotic regression, sustained inflammatory reaction, and inhibition of proliferation of neointima. Cardiologists must be aware of the potential for late thrombosis following even conventional stent implantation.

Adult↗
PubMed2003

Pathogenicity and kinetics of virus propagation in swine infected with the cytopathogenic classical swine fever virus containing defective interfering particles.

To analyze the pathogenicity and in vivo kinetics of the cytopathogenic (cp) classical swine fever virus (CSFV) WB82 strain, which is composed of cp defective interfering (DI) particles and noncytopathogenic (noncp) helper virus (WB82/E(+) strain), WB82 and WB82/E(+) strains were administered separately to domestic pigs. After inoculation with either strain, all pigs showed typical symptoms of classical swine fever (CSF), such as leucopenia and high fever. There were few differences in clinical signs and survival times between each group. However, the appearance of some symptoms of CSF had a tendency to be delayed following infection with the WB82 strain, when compared with the WB82/E(+) strain. Virus isolation and detection of subgenomic (sg) and full-length viral (flv) RNA by RT-PCR was carried out using sera, 10% homogenized organs and oral, nasal and rectal swabs. Both noncytopathogenic helper virus and cp DI particles were detected in samples from pigs infected with the WB82 strain, but only noncp phenotype virus was isolated from pigs infected with the WB82/E(+) strain. Interestingly, the cp DI particles appeared six to seven days later than helper virus in sera from pigs infected with the WB82 strain. Although active cp DI particles could not be isolated from swabs, sg RNA as well as flv RNA was detected in swabs from animals infected with the WB82 strain. These results suggest that progeny cp DI particles are replicated from parent DI particles after noncp virus replication, and subsequently discharged from infected animals. Furthermore, propagation of DI particles or replication of sg RNA, following propagation of helper virus, appears to inhibit the appearance of CSF symptoms induced by virulent helper CSFV.

Animals↗
PubMed2003

Rice stripe virus 23.9 K protein aggregates and forms inclusion bodies in cultured insect cells and virus-infected plant cells.

The genome of Rice stripe virus (RSV, genus Tenuivirus) contains seven open reading frames (ORFs). Little is known about the products of four of these ORFs, including the 23.9 K protein encoded by the virus-sense ORF of RNA3. Western blotting revealed that the 23.9 K protein was synthesized in the host plant and also in the planthopper vector of RSV. Using a baculovirus vector, the 23.9 K protein was expressed, both unfused and fused with red-shifted green fluorescent protein, in Spodoptera frugiperda cells. Inclusion bodies were observed by light microscope in cells expressing fused or unfused proteins. Inclusion bodies in cells expressing the fused protein fluoresced under blue light. By immunoelectron microscopy, electron-dense inclusion bodies in cells expressing the unfused protein were specifically labeled with 23.9 K protein antiserum. Moreover, electron-dense masses labeled with 23.9 K protein antiserum were observed in virus-infected wheat tissue by electron microscopy. This paper thus demonstrates that RSV 23.9 K protein can aggregate in vivo and form inclusion bodies in infected plant tissue.

Animals↗
PubMed2003

Changes of alpha1-protease inhibitor and secretory leukocyte protease inhibitor levels in gingival crevicular fluid before and after non-surgical periodontal treatment.

OBJECTIVES: The possible contribution of alpha1-protease inhibitor (alpha1-PI) and secretory leukocyte protease inhibitor (SLPI) in gingival crevicular fluid (GCF) to predict the periodontal disease activity was evaluated. DESIGN: GCF samples were collected at each site before scaling and root planning (SRP), 2 and 4 weeks after SRP. SUBJECTS AND METHODS: Forty-one sites that initially bled on probing in 21 patients with moderate to severe periodontitis were studied. Sites were classified according to the presence or absence of bleeding on probing (BOP) at 4 weeks. In GCF alpha1-PI and SLPI were determined by enzyme-linked immunosorbent assays. RESULTS: A significant decrease was observed in alpha1-PI at 2 and 4 weeks in BOP(-) sites and at 4 weeks in BOP(+) sites. SLPI significantly increased at 2 weeks in BOP(+) site, while SLPI did not significantly differ at both time points in BOP(-) sites and at 4 weeks in BOP(+) sites. GCF alpha1-PI was significantly less at 2 weeks in BOP(-) than in BOP(+) sites. CONCLUSION: At 2 weeks GCF alpha1-PI may reflect the healing response of the periodontal tissues following nonsurgical periodontal treatment. GCF SLPI levels may be influenced by healing.

Adult↗
PubMed2003

Successful treatment of natural killer (NK) cell leukemia following a long-standing chronic active Epstein-Barr virus (CAEBV) infection with allogeneic bone marrow transplantation.

The optimal treatment for natural killer (NK) cell leukemia after chronic active Epstein-Barr virus (CAEBV) infection has not been determined. A 15-year-old boy presented with NK cell leukemia following CAEBV infection for 5 years. The peripheral blood and BM had an increased number of CD3(-)CD56(+) large granular lymphocytes and a monoclonal integration of the EBV genome was detected. Chemotherapy was not sufficiently effective to control the disease. Allogeneic BMT from an HLA-identical sister was performed using a conditioning regimen consisting of total body irradiation, cyclophosphamide and thiotepa. The patient is disease-free with a perfect performance status 24 months after BMT. This is the first report to show that allogeneic BMT is potentially able to cure NK cell leukemia after CAEBV infection.

Adolescent↗
PubMed2003

Release of non-glycosylated polymeric immunoglobulin receptor protein.

Using a recombinant vaccinia virus containing the T7 RNA polymerase, we have established a system for the transient expression of human polymeric immunoglobulin receptor (pIgR) in baby hamster kidney cells, a baby hamster-derived fibroblastic cell line. This transfection system resulted in the successful expression of pIgR in these cells, and Western blot analysis showed that human pIgR was expressed as two different molecular weight forms of 92 and 107 kDa. Treatment with endoglycosidase H showed that the difference between these two forms was due to the glycosylation status of the protein. In order to examine the functional role of glycosylation, we treated the transfected cells with tunicamycin, which prevents a core glycosylation step in the endoplasmic reticulum. Non-glycosylated pIgR was released into the culture medium of the transfected cells, albeit with extremely low efficiency. Taking these results together, we conclude that the glycosylation of pIgR may play a positive role in the efficient transport or release of free pIgR.

Animals↗