Biomedical subjects

K Seguchi

Publications and source records attributed to K Seguchi.

At least 19 recordsLinked to original sources

PubMed2004

Differences between cytotoxicity in photodynamic therapy using a pulsed laser and a continuous wave laser: study of oxygen consumption and photobleaching.

Oxygen consumption at the targeted site has a significant effect on dosimetry in photodynamic therapy (PDT). However, oxygen consumption in PDT using a pulsed laser as a light source has not been clarified. We therefore investigated the dependence of cytotoxicity on the oxygen consumption and the photosensitizer photobleaching of PDT using a pulsed laser by comparing with that using a continuous wave (CW) laser. Mouse renal carcinoma cells (Renca) were incubated with a second-generation photosensitizer, PAD-S31. The cells were then irradiated with either a 670-nm nanosecond pulsed light from the 3rd harmonics of a Nd:YAG laser-pumped optical parametric oscillator with a peak fluence rate of approximately 1 MW/cm(2) at 30 Hz or a 670-nm CW diode laser with a total light dose of 40 J/cm(2). Regardless of laser source, cytotoxic effects exhibited cumulative dose responses to the photosensitizer ranging from 12 to 96 microg/ml. However, cytotoxic effect of PDT using the pulsed light was significantly less than that using the CW light with the photosensitizer concentrations of 24 and 48 microg/ml under identical fluence rates. During PDT, the cells exposed to the pulsed light consumed oxygen more slowly, resulting in a lower amount of oxygen consumption when compared with PDT using CW light. In accordance with oxygen consumption, the pulsed light induced significantly less photobleaching of the photosensitizer than the CW light did. These results indicate that the efficiency of PDT using pulsed light is less when compared with CW light, probably being related to suppressed oxygen consumption during the pulsed light irradiation.

Animals↗

PubMed2002

Critical parameters in the cytotoxicity of photodynamic therapy using a pulsed laser.

Photodynamic therapy (PDT) using a pulsed laser is becoming popular, but its cytotoxic effect is still not clear. We therefore studied the cytotoxicity of PDT using a pulsed laser by changing its irradiation parameters and compared the degrees of cytotoxicity with those of PDT using continuous-wave (CW) light sources. Mice renal cell carcinoma cells were incubated with PAD-S31, a water-soluble photosensitiser of which the excitation peak is 670 nm, and were then irradiated with either a tungsten lamp, a CW diode laser, or a nanosecond pulsed Nd:YAG laser-based optical parametric oscillator system. When the PAD-S31 concentration and total light dose were constant (12 micro g/ml and 40 J/cm(2), respectively), the CW laser caused fluence rate-dependent decrease in cellular proliferation until the fluence rate reached 90 mW/cm(2), at which point inhibition of cellular proliferation was more than 80%. The cytotoxicity then became almost saturated at fluence rates of>90 mW/cm(2). On the other hand, inhibition of cellular proliferation in samples irradiated with the pulsed laser reached 80% even at the fluence rate of 15 mW/cm(2), and, interestingly, the cytotoxicity paradoxically decreased with increase in the fluence rate. Moreover, the cytotoxicity in the PDT using the pulsed laser depended on the repetition rate. The inhibition of cellular proliferation by PDT using 30-Hz irradiation was greater than that by PDT using 5-Hz irradiation when the same fluence rates were used. These results suggest that the efficacy of PDT using a pulsed laser depends considerably on fluence rate and repetition rate.

Animals↗

PubMed2001

Incidentally discovered giant renal arteriovenous malformation.

A case is presented of giant renal arteriovenous malformation (AVM). A 61-year-old woman was admitted to the National Defense Medical College Hospital for further evaluation of a renal cyst. Doppler ultrasonography and magnetic resonance imaging revealed a giant renal AVM, although the patient had no history nor clinical sign suggesting an AVM. Under the diagnosis of a right renal AVM, the patient underwent AVM resection.

Arteriovenous Malformations↗

PubMed2000

Novel human corticosteroid-binding globulin variant with low cortisol-binding affinity.

Corticosteroid-binding globulin (CBG) is the plasma transport protein that regulates the access of glucocorticoid hormones to target cells. Genetic deficiencies of CBG are rare, and only a single human CBG variant (Trancortin Leuven) has been related so far to decreased cortisol-binding affinity. We report here on a 43-yr-old woman, referred for chronic asthenia and hypotension, with repeatedly low morning serum cortisol levels (22-61 nmol/L; normal range, 204-546 nmol/L), normal plasma ACTH levels (38-49 pg/mL; normal, <50 pg/mL), and normal urinary cortisol (10-76 nmol/24 h; normal range, 10-105 nmol/24 h). An increased percent-free (dialysable fraction) serum cortisol (8.7-9.7%, normal range, 2.9-3.9%) suggested abnormal CBG binding activity. Indeed, she had a low serum CBG concentration (24 mg/L vs. 44+/-6 mg/L in normal women), and the affinity of her CBG for cortisol was decreased (association constant, Ka = 0.12 L/nmol vs. 0.82+/-0.29 L/nmol). In her immediate family members, the serum CBG concentration and cortisol-binding activity were normal in her husband, but the four living children had slightly lower serum CBG concentrations than the reference ranges for their pre- and postpubertal status. Measurements of cortisol distribution in undiluted serum indicated that an increase in the percentage of nonprotein-bound cortisol offsets the low cortisol levels to give approximately normal concentrations of free cortisol in serum. Direct sequencing of PCR-amplified exons encoding CBG revealed that the proband was homozygous for a polymorphism (GAC-AAC) in the codon for residue 367, which results in a Asp367-->Asn substitution. Her children were heterozygous for this polymorphism. When this nucleotide change was introduced into a normal human CBG complementary DNA, for expression in Chinese hamster ovary cells, Scatchard analysis demonstrated that the Asn367 substitution reduced the affinity of human CBG for cortisol by approximately 4-fold (Ka = 0.15 L/nmol), as compared to normal recombinant CBG (Ka = 0.66 L/nmol). These results suggest that Asp367 is an important determinant of CBG steroid-binding activity and that normal negative regulation of the hypothalamic-pituitary-adrenal axis is maintained by relatively normal serum-free cortisol concentrations, despite a marked reduction in the steroid-binding affinity of this novel human CBG variant, which we have designated as CBG-Lyon.

Adrenal Cortex Diseases↗

PubMed1999

Secretion of protease nexin-II/amyloid beta protein precursor by human colorectal carcinoma cells and its modulation by cytokines/growth factors and proteinase inhibitors.

Trypsin inhibitors secreted by human colorectal adenocarcinoma cell lines were analyzed by reverse zymography. Among eleven cell lines analyzed, the major inhibitor secreted was protease nexin-II (PN-II), a secreted form of amyloid beta protein precursor (APP) containing a Kunitz-type serine proteinase inhibitor domain. Expression of the APP gene was also confirmed in the cell lines and the main APP mRNA species were PN-II types. The APP gene expression was constant during cell growth in vitro. On the other hand, the rate of extracellular PN-II accumulation markedly increased after long-term serum-free maintenance of the confluent culture. The extracellular accumulation of PN-II was also strongly stimulated either by interleukin-1beta (IL-1beta) treatment or to a lesser extent by basic fibroblast growth factor, tumor necrosis factor-alpha, hepatocyte growth factor or epidermal growth factor. Neither serum depletion- nor IL-1beta-induced stimulation of extracellular PN-II accumulation were accompanied by obvious alteration of the levels of APP mRNA and cellular APP holoprotein, suggesting that the enhanced extracellular accumulation of PN-II might result from up-regulation of the secretory pathway of APP. The IL-1beta-induced PN-II secretion was significantly inhibited by relatively high concentrations (50-200 microg/ml) of aprotinin, a serine proteinase inhibitor, in a dose-dependent manner without obvious cell-toxic effects.

Adenocarcinoma↗

PubMed1998

Sinus histiocytosis with massive lymphadenopathy: a case of multiple dural involvement.

An exceptional case of Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) arising from the meninges in a 60-year-old Japanese man is presented. Computerized tomographic scans and magnetic resonance images demonstrated well-circumscribed tumorous lesions that were homogeneously enhanced with contrast medium. Systemic examination revealed no abnormalities except for a cervical lymphadenopathy and diabetes mellitus. Microscopic examination of the resected specimens showed proliferated histiocytosis and infiltration of plasma cells and lymphocytes. The histology was characterized by the presence of histiocytes demonstrating lymphophagocytosis and immunoreactivity for S-100 protein staining. Immunohistochemical studies and electron microscopy were useful in confirming the diagnosis. The clinical and histopathological features of this disease are discussed.

Brain Diseases↗

PubMed1997

[Acute acalculous cholecystitis as a complication of cerebrovascular disease].

Acute acalculous cholecystitis (AAC) is a potentially life-threatening complication, which is sometimes found in patients with multiple injuries, burns, or after an operation. It is unclear, however, whether AAC occurs after cerebrovascular disease (CVD). We studied the incidence of AAC complicating CVD and the clinical characteristics of AAC that occurs after CVD. One thousand three patients with CVD were studied who had been admitted at the acute stage to Kenwakai Hospital from January 1989 through September 1995 and to Seguchi Hospital of Neurosurgery from January 1993 through September 1995. There were 557 patients with cerebral infarction, 273 with cerebral hemorrhage, 94 with subarachnoid hemorrhage, and 79 with TIA/RIND. Twelve patients developed acute cholecystitis, ten of whom had AAC. Of the ten patients with AAC, six had cerebral infarction, two cerebral hemorrhage, and two TIA/RIND. Eight of ten were male. The incidence of AAC was 1.0% in the CVD patients studied. The majority of the AAC patients showed severe hemiparesis. The time interval from CVD to the onset of AAC ranged from 1 to 89 days, with a mean of 25.1 days. AAC occurred 0 to 16 days (mean 5.8 days) after the start of oral or tube food intake in five patients. The most common initial symptom was fever (70%), whereas abdominal pain was infrequent (20%). All the patients showed elevated CRPs and abnormal ultrasonographic findings for the gallbladder and some also had leukocytosis (60%) and elevated aminotransferase of more than 100 IU/l (30%). Cholecystectomy was performed on four AAC patients, but five were successfully treated with antibiotics. The cause of AAC complicating CVD seems to be multifactorial and probably is related to fasting, increased bile concentration, and arteriosclerosis. Our results strongly suggest that AAC is an unrecognized but important complication during acute stage CVD patients.

Acute Disease↗

PubMed1997

Establishment and characterization of a new human glioblastoma cell line (MGM-1) with highly motile phenotype.

A new cell line MGM-1 was established from a primary tumor of the left temporal lobe with histological diagnosis of glioblastoma multiforme, removed from a 64-year-old Japanese male. The patient died of recurrence and unusual extracranial metastases of the tumor 7 months after the surgery. The cultured MGM-1 cells are spindle or polygonal in shape. After serial passages, glial fibrillary acidic protein became negative immunocytochemically in vitro. The modal chromosome number was 61-64. Doubling time and soft agar colony forming efficiency were 42.9h and 0.4%, respectively (at 25th passage). MGM-1 is a highly motile cell line in vitro and its serum-free conditioned medium is chemotactic and chemokinetic for other glioma cells. Secretion of gelatinases (probably MMP-2/72-kDa type i.v. collagenase) and MMP-9/92-kDa type i.v. collagenase) and urokinase-type plasminogen activator were also investigated. MGM-1 would therefore be useful for studying the mechanisms regulating glioma-cell motility and invasion. The MGM-1 cell line has been propagated continuously by serial passages (more than 100 passages) during the past 4 years.

Brain Neoplasms↗

PubMed1996

Effects of hepatocyte growth factor (HGF) on human glioma cells in vitro: HGF acts as a motility factor in glioma cells.

Expression of c-Met, the receptor for hepatocyte growth factor (HGF), and the biological roles of HGF were examined in cultured human glioma cells. All of the 5 glioma cell lines examined expressed c-Met protein as well as the c-met gene. Expression of the c-met gene was also confirmed in a glioblastoma tissue. Three cell lines (MGM-3, U251, KG-1-C) demonstrated chemotactic response to HGF in a dose-dependent manner. The response was not only chemotactic but also chemokinetic as judged by a checkerboard analysis. The amounts of c-Met mRNA and protein were abundant in the cell lines which showed a migratory response to HGF. Moreover, c-Met protein expression was highest in U251 with the highest migratory response to HGF. Among the cell lines, KG-1-C produced notable amounts of HGF protein as well as of c-Met, suggesting that HGF may act in an autocrine fashion in this case. HGF did not act as an apparent growth factor in the glioma cell lines examined. Furthermore, HGF stimulated the production of metalloproteinase, probably gelatinase A, in U251 cells.

Cell Division↗

PubMed1996

Unilateral tongue atrophy due to an enlarged emissary vein in the hypoglossal canal.

A 16-year-old girl presented to our clinic with right-sided tongue atrophy and fasciculations of 1-year duration. Enlargement of the outer opening of the hypoglossal canal was reveal by conventional and computed tomography of the skull. Magnetic resonance imaging disclosed an enlarged venous system extending from the jugular vein to the internal jugular vein on the right, with low signal density suggestive of a flow void. A right-sided occipital craniotomy was performed. When the hypoglossal canal was opened, an enlarged emissary vein compressing the hypoglossal nerve was identified. This is the first reported case of unilateral tongue atrophy and an enlarged hypoglossal canal due to an enlarged emissary vein.

Adolescent↗

PubMed1995

Targeted disruption of 01H1 encoding a particular H1 histone variant causes changes in protein patterns in the DT40 chicken B cell line.

Six members of the chicken H1 gene family, all of which are located in two major histone gene clusters, have been shown to encode six different protein variants. The intracellular mRNA level from one of them, 01H1, encoding the 01H1 variant composed of 218 amino acid residues, constitutes 9.9% of the total H1 mRNA in the DT40 chicken B cell line. To study the specific role of this particular H1 variant, besides its well-known functions as a linker in chromatin maintenance and as a general repressor of transcription, we used targeted integration to construct heterozygous and homozygous DT40 mutants with disruption of one and two 01H1 alleles, respectively. Analyses of the stable transfectants showed that the growth rate of DT40 was unchanged in the absence of two 01H1 alleles. Moreover, the remaining H1 genes were shown to be expressed more in these mutants than in the wild-type cell lines. Two-dimensional polyacrylamide gel electrophoresis showed that within an almost constant background in the homozygous mutants several cellular proteins newly appeared or increased, while some other proteins disappeared or decreased quantitatively. These variable proteins all differed from those that varied in DT40 mutants deprived of one of the eight chicken H2B genes, H2B-V, encoding a particular H2B variant. These results suggest that the 01H1 variant is involved in the regulation of expression of genes that encode the proteins that vary in 01H1-deleted mutants of DT40 cells.

Alleles↗

PubMed1995

Reverse-zymographic analysis of protease nexin-II/amyloid beta protein precursor of human carcinoma cell lines, with special reference to the grade of differentiation and metastatic phenotype.

Trypsin inhibitors in serum-free conditioned media (SFCM) of various human carcinoma cell lines were analyzed by reverse zymography. Most of the cells secreted high-molecular-weight trypsin inhibitors (HMTI) larger than 100 kDa. The cell lines of colorectal carcinoma origin had a tendency to secrete HMTI whose molecular weight was a little higher than that of the other cell lines. Analysis of SFCM of subclones with different histological differentiation and metastatic/invasive potentials derived from a single pancreatic carcinoma cell line SUIT-2 showed that the HMTI activity in SFCM was correlated to the degree of histological differentiation in vivo and tended to be inversely correlated to their metastatic/invasive capabilities. Immunoblotting analysis revealed that these HMTI were protease nexin-II/amyloid beta protein precursors (PN-II/APP). Semi-quantificative reverse-transcriptase/polymerase-chain reaction study for PN-II/APP mRNAs suggested that the differences in PN-II/APP activities in SFCM between the subclones might be post-transcriptional or post-secretional events. In addition, SFCM of a highly metastatic subclone contained 43-kDa protein which reacted to anti-APP monoclonal antibody (MAb) suggesting that the subclone may have APP-degrading activity.

Adenocarcinoma↗

PubMed1995

A case report of colonic ileus due to eosinophilic nodular lesions caused by Gnathostoma doloresi infection.

Gnathostomiasis is primarily a disease of the skin characterized as creeping eruption or mobile erythema. However, larval Gnathostoma sometimes migrate into an unexpected site to elicit serious illness. Here we describe a case of colonic ileus caused by Gnathostoma doloresi. The patient was a 57-year-old man living in Miyazaki Prefecture, Japan, which is known as an area endemic for this parasite. One week after having eaten a few slices of the flesh of a snake (Agkistrodon halys), he developed severe abdominal pain. An abdominal radiograph revealed multiple gas-fluid levels with a distended bowel of an inverted U shape. A barium enema revealed a tumor in the ascending colon near the hepatic flexure that was surgically removed by simple colonic resection. An oblique section of a parasite surrounded by massive infiltration of eosinophils was found by postoperative histopathologic examination. The entire body of the advanced third-stage larva of G. doloresi was dissected from a specimen-embedded paraffin block.

Animals↗

PubMed1995

Establishment and characterization of a human renal carcinoma cell line MRT-1, with special reference to the production of serine proteinase inhibitors.

A new human cell line MRT-1 was established from a metastatic lymph node of renal cell carcinoma of a 47 years old Japanese male. The cultured MRT-1 cells exhibit an epithelial appearance and contain lipid vacuoles in their cytoplasm in vitro. The modal chromosome number was 70. Doubling time and plating efficiency were 32.5 h and 5%, respectively (at the 47th passage). Injection of 1X10(6) MRT-1 cells beneath the renal capsule of nude mice resulted in tumor formation resembling the original tumor. Serine proteinase inhibitors produced by the cell line were analyzed. The cultured cells produced alpha 1-antitrypsin (alpha 1-AT) and plasminogen activator inhibitor-1 (PAl-1) into the conditioned medium. Most of the MRT-1 derived alpha 1-AT had lost the affinity to Concanavalin A when compared to the normal plasma alpha 1-AT.

Animals↗

PubMed1994

Subarachnoid hemorrhage due to rupture of infundibular dilation of a circumflex branch of the posterior cerebral artery: case report.

The authors describe a rare case in which an infundibular dilation at the origin of a circumflex branch of the P1 segment of the posterior cerebral artery caused subarachnoid hemorrhage. Wrapping was performed by a subtemporal approach in the delayed stage. At the time of surgery, the rupture point was found in the infundibular dilation.

Arcuate Nucleus of Hypothalamus↗

PubMed1994

Protein-free culture of the human pancreatic cancer cell line, SUIT-2.

A human pancreatic cancer cell line (SUIT-2), usually cultured in serum-supplemented medium (DMEM/FBS), was adapted to protein-free conditions using a 1:1 mixture of DMEM and Ham's F12 medium (DMEM/F12). The cells have been maintained in DMEM/F12 for more than 2 years, with over 50 passages. The SUIT-2 cells grew in DMEM/F12 with a doubling time of 35.7 h, which was similar to that in DMEM/FBS (35.0 h). The cellular morphology was similar in both media. Type IV collagenolytic activity was detected in the conditioned media from cells grown in DMEM/F12. The secretion of CEA and CA19-9 initially decreased in DMEM/F12. CEA was not detected after passage 5 (p5) but the concentration of CA19-9 did not decrease further after the first few serial passages in protein-free medium. Xenografts of SUIT-2 cells cultured in DMEM/F12 remained tumorigenic and could form metastatic tumors in nude mice. In conclusion, SUIT-2 cells grown in protein-free media continued to produce CA19-9 and type IV collagenase in vitro and formed metastatic tumors in vivo.

Animals↗

PubMed1993

Properties of alpha 1-antitrypsin secreted by human adenocarcinoma cell lines.

alpha 1-Antitrypsin; (alpha 1-AT) produced by various human carcinoma (non-hepatoma) cell lines were analyzed. Five out of eight cell lines secreted detectable amounts of alpha 1-AT into the conditioned media. All were adenocarcinoma cell lines. The tumor cell-derived alpha 1-ATs had higher molecular weights (MW) than the normal plasma form. Most of this difference was an overall reflection of altered N-glycosylation. As judged by binding of lectins, the glycosylation had shifted towards higher levels of triantennary oligosaccharides and higher levels of fucosylation. The conditioned media also contained lower MW alpha 1-AT species, possibly, proteolytically cleaved forms.

Adenocarcinoma↗

PubMed1993

Establishment and characterization of a human lung adenocarcinoma cell line (LC-2/ad) producing alpha 1-antitrypsin in vitro.

A new human cell line, LC-2/ad was established from pleural effusion of pulmonary adenocarcinoma of a 51 year old Japanese female. The LC-2/ad cells exhibit an epithelial appearance and a tendency to form small domes as observed with phase-contrast microscopy. The modal chromosome number was 53-56. Plating efficiency and doubling time were 6.8% and 58 h, respectively (32th passage). Immunocytochemically, the cells were strongly positive for CEA and cytokeratins including cytokeratin no. 18 which is present in simple epithelia. Ultrastructurally, the cultured cells were characterized by well-formed junctional complexes and microvilli. Subcutaneous injection of 5 x 10(6) cells into a nude mouse resulted in tumor formation classified histologically as a moderately differentiated adenocarcinoma. This cell line produced at least two functionally active trypsin inhibitors together with several proteinases in vitro. The main inhibitor was purified partially from the serum-free conditioned medium and confirmed immunologically as human alpha 1-antitrypsin (AAT). Immunohistochemically, the xenografted tumor was also positive for AAT. The cell line LC-2/ad is useful for the study of tumor-derived serine proteinase inhibitors, in particular AAT.

Adenocarcinoma↗