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K Koyama

Publications and source records attributed to K Koyama.

At least 19 recordsLinked to original sources
PubMed2005

Antigenic epitope for sperm-immobilizing antibody detected in infertile women.

CD52 is a glycosylphosphatidylinositol (GPI) anchor protein occurring in lymphocytes, the epididymis, seminal plasma and on ejaculated sperm surface. The molecular structure of male reproductive tract CD52 (mrtCD52) is quite different from that of lymphocyte CD52 except for a peptide sequence comprising 12 amino acids. The carbohydrate molecule may thus provide antigenic epitopes to females. The repeated N-acetyllactosamine units of the N-linked carbohydrate present in the mrtCD52 were identified as a pathogenic antigen for infertility using a monoclonal antibody (MAb H6-3C4) generated from an infertile patient's peripheral blood lymphocyte. We suggested also the possible presence of O-linked carbohydrate in human mrtCD52, although it is not known whether this carbohydrate is immunogenic or not. This article gives an overview of the structure and function of mrtCD52 as well as the fertilization-blocking mechanism of the antibody against this molecule.

Antibodies, Monoclonal↗
PubMed2005

[Simulation of lung lobe resection with personal computer].

Various patterns of branching are seen for pulmonary arteries and veins in the lung hilum. However, thoracic surgeons usually cannot expect to discern much anatomical detail preoperatively. If the surgeon can gain an understanding of individual patterns preoperatively, the risks inherent in exposing the pulmonary vessels in the hilum can be avoided, reducing invasiveness. This software will meet the increasing needs of them in video-assisted thoracoscopic surgery (VATS) which prefer lesser dissections of the vessels and bronchus of hilum. We have produced free application software, where we can mark on pulmonary arteries, vein, bronchus and tumor of the successive images of computed tomography (CT). After receiving a compact disk containing 60 images of 2 mm CT slices, from tumor to hilum, in DICOM format, we required only 1 hour to obtain 3-dimensional images for a patient with other free software (Metasequoia LE). Furthermore, with Metasequoia LE, we can simulate cut the vessels and change the figure of them 3-dimensionally. Although the picture image leaves much room for improvement, we believe it is very attractive for residents because they can simulate operations.

Computer Simulation↗
PubMed2004

Role of IL-18 in pathogenesis of endometriosis.

BACKGROUND: Endometriosis is a complex disease associated with a wide range of immune responses, including pain, adhesion, exudation of peritoneal fluid, elevation of cytokine levels and generation of autoantibodies. Interleukin (IL)-18 is a strong pleiotropic cytokine known to be involved in various immune diseases. The aim of this study is to elucidate the role of IL-18 in the pathogenesis of endometriosis. METHODS: IL-18 and IL-1beta concentrations were measured in the peritoneal fluid and sera of 39 endometriosis patients and 15 control women. Expression of IL-18 and IL-18 receptor alpha-chain (IL-18Ralpha) was analysed in endometriotic tissues immunohistochemically. The effects of IL-18 on cyclooxygenase (COX)-II gene expression were analysed in peritoneal fluid monocytes and endometriotic cells of endometriosis patients. RESULTS: IL-18 concentrations in the peritoneal fluid of endometriosis patients averaged 592.57 +/- 108.27 pg/ml, significantly higher than 260.50 +/- 55.88 pg/ml in non-endometriotic samples. IL-18 concentrations in the serum did not differ significantly between endometriosis and control patients. Similarly, no significant differences were observed in IL-1beta concentrations in either the peritoneal fluid or the serum. IL-18 and IL-18Ralpha were expressed in endometriotic tissues. IL-18Ralpha expression was also observed in cells infiltrating into the inflammatory area of the endometriosis patients. COX-II was induced in peritoneal fluid monocytes and in endometriotic cells in response to IL-18 stimulation. CONCLUSIONS: The elevation of IL-18 in the peritoneal fluid of endometriosis patients and the induction of COX-II in peritoneal monocytes by IL-18 suggest that IL-18 plays a pathogenic role in endometriosis.

Adult↗
PubMed2004

Possible presence of O-linked carbohydrate in the human male reproductive tract CD52.

Male reproductive tract CD52 (mrtCD52) is an antigen recognized by a complement-dependent sperm-immobilizing monoclonal antibody (SI-Abs) derived in an infertile patient. The molecule has been shown to contain a unique N-linked carbohydrate that does not cross-react with other tissues. In this study, we have investigated whether O-linked carbohydrate as well as N-linked carbohydrate is present in mrtCD52 using specific lectins and anti-CD52 core peptide antiserum. The lectin PNA, which recognizes O-linked carbohydrate [Galbeta1-3GalNAc], reacted with mrtCD52 and showed a similar polymorphic reaction pattern to that of the anti-peptide antiserum in western blotting analysis on two-dimensional SDS-PAGE. The PNA-reactive spots disappeared after removal of O-linked carbohydrate, but not after removal of N-linked carbohydrate. These results suggest that O-linked carbohydrate is present in mrtCD52. The moiety may possibly contribute to a specific antigenic epitope of mrtCD52.

Antibodies, Monoclonal↗
PubMed2004

Predicted values of propofol EC50 and sevoflurane concentration for insertion of laryngeal mask Classic and ProSeal.

BACKGROUND: A new laryngeal mask airway, the ProSeal (PLMA), is said to be more difficult to insert than the laryngeal mask airway Classic (CLMA) using propofol anaesthesia. Therefore, we expected a greater dose of propofol and sevoflurane to be required to insert the PLMA compared with the CLMA. We determined the effective concentration 50% (EC(50)) of propofol and end-tidal sevoflurane to allow insertion of the PLMA and the CLMA. METHODS: Seventy-six elective female patients (aged 20-60 yr and ASA I-II) were randomly assigned to one of four groups. Either a PLMA or a CLMA was inserted using either propofol target controlled infusion or sevoflurane. Both propofol and sevoflurane targets were determined with a modified Dixon's up-and-down method. After equilibration between the predetermined blood and effect site concentrations, which had been held steady for more than 10 min, LMA insertion was attempted without neuromuscular block. RESULTS: The predicted EC(50CLMA) and EC(50PLMA) for propofol were 3.14 (0.33) and 4.32 (0.67) micro g ml(-1). E'(CLMA) and E'(PLMA) of sevoflurane (mean (SD)) were 2.36 (0.22) and 2.82 (0.45)% (P<0.01 and 0.05, respectively). CONCLUSIONS: The estimated concentration of propofol and the sevoflurane concentration needed to allow insertion of the ProSeal are respectively 38 and 20% greater than those needed for insertion of the Classic LMA.

Adult↗
PubMed2004

A new walking orthosis for paraplegics: hip and ankle linkage system.

For paraplegics, two major disadvantages of hip-knee-ankle-foot orthotic systems that have a medial single hip joint are the short stride and horizontal rotation of the pelvis. The authors consider the pelvic rotation is caused by two factors; one is the lack of a mechanism to assist hip flexion, and the other is fixed ankle joints that cause instability when the step length becomes longer. Users must rotate their pelvis to initiate a swing in their legs and to achieve stability by making their two legs as parallel as possible in order to avoid losing balance. To overcome those disadvantages, the authors developed a new orthosis named "HALO" (Hip and Ankle Linked Orthosis), which has a linking mechanism that connects both ankle joints with a medial single hip joint. This new orthosis allows users to keep both feet always parallel to the floor while walking, and assists the swinging of the leg when the contralateral ankle is flexed dorsally by loading. Gait analysis revealed that the pelvic rotation with "HALO" either in parallel bars or with Lofstrand crutches was within 20 degrees, which was within the physiologically normal level.

Adult↗
PubMed2003

Cancer incidence in children and young adults did not increase relative to parental exposure to atomic bombs.

We have examined whether parental exposure to atomic bomb radiation has led to increased cancer risks among the offspring. We studied 40,487 subjects born from May 1946 through December 1984 who were cancer-free in January 1958. One or both parents were in Hiroshima or Nagasaki at the time of the bombing and for childbirth. Using population-based tumor registry data we analyzed cancer incidence data from 1958 to 1997 by Cox regression models, and we examined the effects of both paternal and maternal irradiation with adjustment for city, sex, birth year, and migration. During follow-up, 575 solid tumor cases and 68 hematopoietic tumor cases were diagnosed. Median age at diagnosis was 39.7 years. Median doses were 143 millisierverts for 15,992 exposed (5+ millisierverts or unknown dose) fathers and 133 millisierverts for 10,066 exposed mothers. Cancer incidence was no higher for subjects with exposed parents than for the reference subjects (0-4 millisierverts), nor did the incidence rates increase with increasing dose. For 3568 subjects with two exposed parents, the adjusted risk ratio for all cancer was 0.97 (95% confidence interval 0.70-1.36). Because of the small number of cases, however, we cannot exclude an increase in cancer incidence at this time.

Adolescent↗
PubMed2003

Brachial-ankle pulse wave velocity measured automatically by oscillometric method is elevated in diabetic patients with incipient nephropathy.

AIMS: To examine whether brachial-ankle pulse wave velocity (baPWV), a possible early marker of atherosclerotic vascular damage, is associated with albuminuria in patients with Type 2 diabetes. METHODS: BaPWV was measured by automatic oscillometric method in 346 Type 2 diabetic patients with normoalbuminuria (a mean level of three times measurements of albumin-to-creatinine (ACR)<30 microg/mg creatinine; n=200), incipient nephropathy (a mean level of ACR> or =30 and <300 microg/mg creatinine; n=119), and clinical nephropathy (a mean level of ACR> or =300 microg/mg creatinine; n=27), and without peripheral vascular disease. RESULTS: BaPWV (cm/s) was significantly higher in patients with incipient nephropathy (1722 +/- 382) and clinical nephropathy (1763 +/- 322) than in patients with normoalbuminuria (1559 +/- 343, P<0.0001, respectively). By univariate analysis it correlated significantly with age (r=0.44, P<0.0001), systolic blood pressure (r=0.55, P<0.0001), diastolic blood pressure (r=0.42, P<0.0001), albuminuria (r=0.24, P<0.0001) and HbA1C (r=0.11, P<0.05). Albuminuria revealed an independent significant association with baPWV (P<0.01) after adjustment for age, sex, smoking, BMI, HbA1C, hyperlipidemia, and hypertension. Multiple regression analysis showed age, diastolic blood pressure and albuminuria were independently associated with baPWV (adjusted R2=0.42, P<0.0001). CONCLUSIONS: The results might indicate a possible link between the pathogenesis of atherosclerosis and diabetic nephropathy. Future studies are needed to clarify the usefulness and its predictable value.

Aged↗
PubMed2003

Epitope analysis for human sperm-immobilizing monoclonal antibodies, MAb H6-3C4, 1G12 and campath-1.

Human monoclonal antibody, MAb H6-3C4, possesses strong sperm immobilizing activity. MAb H6-3C4 has been suggested by several research groups to react with a carbohydrate moiety of male reproductive tract CD52 (mrtCD52). In the present study, we analysed the epitope on mrtCD52 for MAb H6-3C4 and found that it was polymorphic in Western blot analysis and disappeared after enzymatic removal of the N-linked carbohydrate moiety. Two other monoclonal antibodies (1G12, campath-1) with sperm-immobilizing activity recognized mrtCD52 in a polymorphic manner similar to MAb H6-3C4. Further analysis showed that 1G12 recognized a structure formed by the peptide and/or a glycosylphosphatidylinositol (GPI) anchor portion as does campath-1. Results of a lectin binding assay suggested the presence of O-linked carbohydrates on mrtCD52. Our results also indicated that the peptide portion of CD52 could serve as an epitope for sperm-immobilizing antibodies. It was concluded that the epitope of MAb H6-3C4 is similar to, but distinct from, those of 1G12 and campath-1, and that mrtCD52 contains different antigenic epitopes.

Antibodies, Monoclonal↗
PubMed2003

Assessment of myocardial viability with a positron coincidence gamma camera using fluorodeoxyglucose in comparison with dedicated PET.

The use of dual-head gamma camera modified positron coincidence detection (PCD) is a new, alternative method of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) imaging. This study investigated the potential ability of evaluating myocardial viability in patients with ischaemic heart disease by FDG imaging using PCD. A total of 21 patients (18 male, three female; mean age 59.7+/-8.5 years) with a history of previous myocardial infarction and confirmed coronary angiography underwent FDG PCD and FDG PET after oral glucose loading (75 g). Quantitative analysis was compared between images of FDG PCD and FDG PET. A significant linear correlation between the segmental percentage of FDG uptake obtained by PCD and PET was observed (r=0.63, P<0.001). By receiver operating characteristic (ROC) analysis, using FDG PET as the 'gold standard', at the 50% threshold value in PET, FDG PCD showed a sensitivity of 92% and specificity of 63% in detecting myocardial viability. Regional analysis showed lower agreement of FDG PCD and FDG PET in the inferior (79%) and septal (70%) walls compared with the other walls. Quantitative evaluation of myocardial viability using FDG PCD yielded comparable clinical results in apex, anterior and lateral walls to that of FDG PET. However, the agreement was lower in the inferior and septal walls. Therefore, results of FDG PCD should be carefully interpreted in evaluating myocardial viability in the inferior and septal walls. The application of a measured attenuation correction and scatter correction are needed to improve the detectability of myocardial viability in FDG imaging by coincidence gamma camera.

Aged↗
PubMed2002

Electron acceleration and high-order harmonic generation by an intense short pulse laser in a magnetic field.

Electron acceleration and short-wavelength radiation generation by an intense, short, linearly polarized laser pulse in an external magnetic field parallel to that of the light wave is investigated classically. It is found that enhanced electron acceleration by the laser can occur. After the pulse has passed, much of the energy gained by the electron is retained in its relativistic cyclotron motion. The electron emits radiation at high harmonics of the cyclotron frequency until the static magnetic field decays.

Journal Article↗
PubMed2002

Chaotic mixing generated by acoustic streaming.

The acoustic mixer presented in this paper is a closed cylinder containing chemical solutions. The ultrasound was generated in a water bath outside of the cylinder. The mixing efficiency was measured by using a laser-photodiode system and by mixing iodine and sodium thiosulfate. Iodine solution has a light brown color which becomes transparent if the solution is mixed with sodium thiosulfate. The unmixed regions of the solution in the container remain dark. Starch was used to make the solution darker. Considering the relative position between the cylinder and the transducer, it was shown that displacements parallel to the axes of the streaming have little effect on the mixing speed. Indeed, the distance of the cylinder from the center of the streaming is more important to obtain ideal mixing performances. The frequency and size of the transducers has been investigated too and little effect was found. In contrast, the wave amplitude seems to be the biggest factor in obtaining rapid mixing.

Journal Article↗
PubMed2002

Structure-antiemetic-activity of some diarylheptanoids and their analogues.

The structure-activity relationship of diarylheptanoids and their analogues inhibitory of emesis induced by copper sulfate in young chicks was investigated by testing 19 compounds. The compounds are 5 diarylheptanoids isolated from Alpinia katsumadai (Zingiberacea), 5 chemical derivatives of them, 6 analogues isolated from Zingiber officinale rhizome (Zingiberaceae), and 3 analogues available on the market. Among them, two types of essential functional structure of diarylheptanoids and their analogues showed the inhibitory effects against emesis.

Animals↗
PubMed2001

Modulation of 11 beta-hydroxysteroid dehydrogenase type 2 activity in Ishikawa cells is associated with changes in cellular proliferation.

An important determinant of the potency of steroid hormones is the presence of activating and inactivating enzymes in target cells. The 11 beta-hydroxysteroid dehydrogenase type 1 and type 2 enzymes (11 beta HSD1 and 11 beta HSD2) modulate glucocorticoid action and may be important in regulating cellular growth. In the present study we examined 11 beta-hydroxysteroid dehydrogenase in Ishikawa endometrial cancer cells to see if modulation of enzyme activity could potentiate the antiproliferative effects of glucocorticoids. Ishikawa cells contain an NAD dependent enzyme migrating at 41 kDa on Western blots, consistent with the presence of the glucocorticoid-inactivating enzyme 11 beta HSD2, while the NADP dependent 11 beta HSD1 is barely detectable. Given that glucocorticoids decrease cellular proliferation we asked whether inhibition of 11 beta HSD2 could further enhance this effect. Cultivation of cells in the presence of 1 microM cortisol resulted in an elevation of 11 beta HSD2 and this was associated with a decrease in cell number. Enzyme activity and cell proliferation showed a biphasic response to the synthetic anti-progestin and anti-glucocorticoid RU38486, with < or =10 nM exerting agonistic effects and > or =100 nM producing antagonist effects in the presence of 1 microM cortisol. Inhibition of 11 beta HSD2 activity by glycyrrhetinic acid did not enhance the anti-proliferative effects of 1 microM cortisol, but the inhibitor showed significant antiproliferative activity in the absence of added glucocorticoid, consistent with protection of the low levels of glucocorticoids present in culture medium. Interestingly, the commonly used 11 beta HSD inhibitor, Carbenoxolone, did not block 11 beta HSD2 activity in whole Ishikawa cells, and there was no effect on cell proliferation, however, complete inhibition of 11 beta HSD2 was achieved in cellular homogenates suggesting that a barrier exists to entry of the inhibitor into intact cells. This study suggests that inhibition of 11 beta HSD2 activity can enhance the antiproliferative effects of low, but not high concentrations of glucocorticoids, and that beneficial effects may be attained in vivo at the nadir of diurnal glucocorticoid levels.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗