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Biomedical subjects

K Kaneko

Publications and source records attributed to K Kaneko.

At least 127 records · Page 7Linked to original sources
PubMed2000

Determination of urate crystal formation using flow cytometry and microarea X-ray diffractometry.

Gout is known to be induced by monosodium urate (MSU) crystals. The formation of MSU crystals is the first step of gouty inflammation. Detecting the early stage of crystallization accurately is considered to be important in understanding the mechanism of gouty arthritis. In this study, we employed flow cytometry (FCM) to detect small amounts of crystals produced in a supersaturated solution of uric acid. FCM was sensitive and crystals were determined at 2 h after the beginning of reaction. Gamma-globulin accelerated the formation rate time-dependently and dose-dependently. Low levels of lactic acid (less than 1.0 mg/ml) did not affect the formation rate but lactic acid of 2.0 mg/ml enhanced the formation of urate crystals. The crystals obtained with 2.0 mg/ml of lactic acid were analyzed with a microarea X-ray diffractometer and were shown to be a mixture of MSU and uric acid. FCM is a very useful method to determine the formation of crystals. Furthermore, analysis with a microarea X-ray diffractometer can provide detailed information about crystal composition.

Crystallization↗
PubMed2000

Increased lipid peroxidation in the brains of aceruloplasminemia patients.

Aceruloplasminemia is characterized by excessive neurovisceral accumulation of iron due to mutations in the ceruloplasmin gene. We report that the levels of malonaldehyde (MDA) and 4-hydroxynonenals (4-HNE) were elevated both in the frontal cortex and putamen in two patients with aceruloplasminemia compared with those in controls. Immunohistochemical analysis with an antibody raised against HNE-modified protein showed a large number of immunoreactive neurons and glias in the brain of a patient. MDA and 4-HNE are good indicators of lipid peroxidation because they are generated in the process of oxidation of polyunsaturated fatty acids. The data strongly suggest that the increase of oxygen free radicals associated with excessive iron accumulation plays an important pathogenic role in the process of neuronal cell death in the brains of patients with aceruloplasminemia.

Aged↗
PubMed2000

Sites of action of protein kinase C and phosphatidylinositol 3-kinase are distinct in oxidized low density lipoprotein-induced macrophage proliferation.

Oxidized low density lipoprotein (Ox-LDL) can induce macrophage proliferation in vitro. To explore the mechanisms involved in this process, we reported that activation of protein kinase C (PKC) is involved in its signaling pathway (Matsumura, T., Sakai, M., Kobori, S., Biwa, T., Takemura, T., Matsuda, H., Hakamata, H., Horiuchi, S., and Shichiri, M. (1997) Arterioscler. Thromb. Vasc. Biol. 17, 3013-3020) and that expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) and its subsequent release in the culture medium are important (Biwa, T., Hakamata, H., Sakai, M., Miyazaki, A., Suzuki, H., Kodama, T., Shichiri, M., and Horiuchi, S. (1998) J. Biol. Chem. 273, 28305-28313). However, a recent study also demonstrated the involvement of phosphatidylinositol 3-kinase (PI3K) in this process. In the present study, we investigated the role of PKC and PI3K in Ox-LDL-induced macrophage proliferation. Ox-LDL-induced macrophage proliferation was inhibited by 90% by a PKC inhibitor, calphostin C, and 50% by a PI3K inhibitor, wortmannin. Ox-LDL-induced expression of GM-CSF and its subsequent release were inhibited by calphostin C but not by wortmannin, whereas recombinant GM-CSF-induced macrophage proliferation was inhibited by wortmannin by 50% but not by calphostin C. Ox-LDL activated PI3K at two time points (10 min and 4 h), and the activation at the second but not first point was significantly inhibited by calphostin C and anti-GM-CSF antibody. Our results suggest that PKC plays a role upstream in the signaling pathway to GM-CSF induction, whereas PI3K is involved, at least in part, downstream in the signaling pathway after GM-CSF induction.

Androstadienes↗
PubMed2000

Micropore Filling of Supercritical Xe in Micropores of Activated Carbon Fibers.

The adsorption isotherms of Xe vapor at 196 K and supercritical Xe at 300 K on activated carbon fibers of different pore widths were gravimetrically measured. The adsorption isotherms of Xe vapor were compared with the N(2) adsorption isotherms. A Dubinin-Radushkevich (DR) plot of the adsorption isotherms of Xe vapor showed a good linearity, indicating that Xe vapor is adsorbed by the representative micropore filling mechanism. The adsorption isotherms of supercritical Xe were approximated by the Langmuir equation. The saturated adsorption amounts of supercritical Xe, W(L), were in the range of 0.14 to 0.22 ml g(-1). The adsorption isotherms of supercritical Xe were described by the supercritical DR equation, which provides the quasisaturated vapor pressure P(0q). Both P(0q) and W(L) lead to the reduced isotherm, which can describe three isotherms. The obtained reduced isotherm derived from the isotherms of supercritical Xe could describe even those of Xe vapor. Hence, both Xe vapor and supercritical Xe should be adsorbed by the same mechanism. The isosteric heat of Xe adsorption was greater than the enthalpy of vaporization of Xe by more than 12 kJ mol(-1). These results suggest that Xe molecules are stabilized in the form of a cluster in micropores even at 300 K. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

A synthetic peptide initiates Gerstmann-Sträussler-Scheinker (GSS) disease in transgenic mice.

The molecular basis of the infectious, inherited and sporadic forms of prion diseases is best explained by a conformationally dimorphic protein that can exist in distinct normal and disease-causing isoforms. We identified a 55-residue peptide of a mutant prion protein that can be refolded into at least two distinct conformations. When inoculated intracerebrally into the appropriate transgenic mouse host, 20 of 20 mice receiving the beta-form of this peptide developed signs of central nervous system dysfunction at approximately 360 days, with neurohistologic changes that are pathognomonic of Gerstmann-Sträussler-Scheinker disease. By contrast, eight of eight mice receiving a non-beta-form of the peptide failed to develop any neuropathologic changes more than 600 days after the peptide injections. We conclude that a chemically synthesized peptide refolded into the appropriate conformation can accelerate or possibly initiate prion disease.

Amino Acid Sequence↗
PubMed2000

Endogenous adenosine regulates the effects of low-frequency stimulation on the induction of long-term potentiation in CA1 neurons of guinea pig hippocampal slices.

A train of low-frequency afferent stimuli (LFS, 1 Hz, 1000 pulses), given 60 min prior to a tetanus (100 Hz, 100 pulses), suppresses the induction of long-term potentiation (LTP) in which a short-term potentiation decreases gradually back to the pre-tetanic level within 40-50 min (LTP suppression). We investigated the effects of adenosine A1 or A2 receptor antagonists (8-cyclopentyltheophylline (8-CPT) and CP-66713, respectively) on LTP suppression in CA1 neurons of guinea pig hippocampal slices. When the LFS was delivered in the presence of 8-CPT (1 microM), LTP suppression was not significantly affected. However, when LFS was delivered in the presence of CP-66713 (10 microM), LTP suppression was inhibited, leading to successful LTP induction. These results indicate that endogenous adenosine, acting via A2 receptors, is involved in the mechanism of LTP suppression.

Adenosine↗
PubMed2000

High rate of TTV infection in multitransfused patients with pediatric malignancy and hematological disorders.

The prevalence of transfusion-transmitted virus (TTV) infection has not been known in patients suffering from pediatric malignancies and hematological disorders who receive blood transfusion and/or blood products during treatment. Blood samples were taken from 75 patients. TTV infection was identified when TTV DNA was detected in serum by a polymerase chain reaction (PCR) assay. Hepatitis C virus (HCV) and hepatitis G virus (HGV) RNA were also assayed by PCR. TTV DNA was detected in 38 of 75 patients (51%). In 4 of 38 patients, the amount of blood transfused was less than 3 units. By time since last transfusion, TTV DNA was detected in 12 of 35 patients after more than 4 years, 12 of 21 between 1 and 4 years, and 14 of 19 within 1 year. Six patients had mixed infection of TTV and HCV, and 12 patients had mixed infection of TTV and HGV. Three different kinds of virus were found simultaneously in serum from 3 patients. Eight out of 75 patients showed abnormal levels of alanine aminotransferase (ALT) (>40 IU/liter), and 3 of them had TTV DNA. All patients who had TTV DNA and elevated ALT levels also were positive for HCV RNA and HGV RNA. The prevalence of TTV infection is high in patients with pediatric malignancies and hematological disorders after episodes of blood transfusion. Transfusion is one of the most important risk factors for TTV infection regardless of the amount of blood transfused.

Adolescent↗
PubMed2000

Wavelet compression on detection of brain lesions with magnetic resonance imaging.

The purpose of this report is to assess clinically acceptable compression ratios on the detection of brain lesions at magnetic resonance imaging (MRI). Four consecutive T2-weighted and the corresponding T1-weighted images obtained in 20 patients were studied for 109 anatomic sites including 50 with lesions and 59 without lesions. The images were obtained on a 1.5-T MR unit with a pixel size of 0.9 to 1.2 x 0.47 mm and a section thickness of 5 mm. The image data were compressed by wavelet-based algorithm at ratios of 20:1, 40:1, and 60:1. Three radiologists reviewed these images on an interactive workstation and rated the presence or absence of a lesion with a 50 point scale for each anatomic site. The authors also evaluated the influence of pixel size on the quality of image compression. At receiver operating characteristic (ROC) analysis, no statistically significant difference was detected at a compression ratio of 20:1. A significant difference was observed with 40:1 compressed images for one reader (P = .023), and with 60:1 for all readers (P = .001 to .012). A root mean squared error (RMSE) was higher in 0.94- x 0.94-mm pixel size images than in 0.94- x 0.47-mm pixel size images at any compression ratio, indicating compression tolerance is lower for the larger pixel size images. The RMSE, subjective image quality, and error images of 10:1 compressed 0.94- x 0.94-mm pixel size images were comparable with those of 20:1 compressed 0.94- x 0.47-mm pixel size images. Wavelet compression can be acceptable clinically at ratios as high as 20:1 for brain MR images when a pixel size at image acquisition is around 1.0 x 0.5 mm, and as high as 10:1 for those with a pixel size around 1.0 x 1.0 mm.

Algorithms↗
PubMed2000

Incidence of neonatal hypoglycemia in large-for-gestational-age infants of dichorionic twin pregnancies.

The aim of this study was to estimate standards of large-for-gestational-age (LGA) infants of twin pregnancies based on the incidence of neonatal hypoglycemia. We examined 277 dichorionic twin infants (in 201 dichorionic twin pregnancies) who were delivered weighing > or = 2,500 g at 37-41 weeks of gestation. LGA in twin pregnancies was identified when the infant deviated > by 1.5SD from the mean gestational age of this study (LGA based on the twin pregnancy standard), or when the infant deviated by >1.5 SD of the intrauterine growth curve of Japanese (LGA based the singleton pregnancy standard). Using the twin pregnancy standard, the incidence of neonatal hypoglycemia in LGA twin infants was not measurably different from that in appropriate-for-gestational-age (AGA). However, using the singleton pregnancy standard, the incidence of neonatal hypoglycemia was significantly higher than that in AGA infants. In conclusion, LGA in twin pregnancies should be studied based on the singleton pregnancy standard to assess the incidence of neonatal hypoglycemia.

Birth Weight↗
PubMed2000

Surgical treatment of old pelvic fractures.

We report on 4 patients, aged 24-51 years, with untreated pelvic ring fractures. The chief complaints were gait disturbances and pain in the buttocks and lower limb. The period between the initial injury and the surgical treatment ranged from 2.5 months to 3 years. Palsy was not improved, but pain and gait ability was improved in all patients.

Accidental Falls↗
PubMed2000

Pathologic changes in the common bile duct of an experimental model with pancreaticobiliary maljunction without biliary dilatation.

Pancreaticobiliary maljunction (PBM), a congenital anomaly, causes regurgitation of pancreatic juice into the biliary tract, where it exerts a hazardous influence. However, changes in the common bile duct (CBD) remain obscure due to a lack of suitable experimental models. Using cats, we have developed an experimental model of PBM without bile-duct dilatation that allows the pure effects of PBM to be studied. Histologic and cellular kinetic changes in the CBD were analyzed in 6 controls and 9 experimental animals that survived for more than 6 months. CBD sections were stained with hematoxylin and eosin and a monoclonal antibody to the proliferating cell nuclear antigen (PCNA). Invaginations of the bile-duct epithelium or parietal sacculi increased, and peribiliary glands were well-developed. PCNA-positive cells significantly increased in the CBD, especially in the parietal sacculi and glands. It is concluded that PBM increases the cell cycle in CBD epithelium and subsequently developed peribiliary glands. These developed glands may be associated with the formation of protein plugs, often seen in patients with PBM.

Animals↗
PubMed2000

Hypoplasia of bilateral humeral trochlea associated with bilateral ulnar nerve palsy.

We document a case of bilateral ulnar nerve palsy that developed in an 27-year-old Japanese man who had bilateral hypoplasia of the humeral trochlea. Surgical management produced good results regarding the ulnar nerve palsy. The pathogenesis of the nerve paresis in this particular condition is discussed. There have been no reports outside Japan. Whether this deformity occurs only in persons of Japanese extraction or is simply overlooked by foreign surgeons is an interesting question.

Adult↗
PubMed2000

The initial fixation of the press-fit acetabular shell--clinical observation and experimental study.

The initial solid fixation of an uncemented acetabular component affects the amount of bone ingrowth. We had several problems with broken screws in cases of acetabular revision. In recent years, the development of uncemented components without screws has attempted to improve these problems. We started to use "press-fit"-type acetabular shells in November 1996. Our thirty cases undergoing 2 mm under-reaming show good initial stability. The aim of our biomechanical study was to assess the most suitable degree of under-reaming of the bony acetabulum for the implantation of an uncemented hemispherical porous coated component.

Acetabulum↗
PubMed2000

Non-lupus nephropathy associated with antiphospholipid antibodies.

Renal biopsy was performed in a 12-year-old girl with hematuria and proteinuria which was first detected at the age of 7, and the findings were the mesangial proliferative glomerulonephritis with IgG and C3 deposits. The routine blood examination for the biopsy disclosed the presence of the prolonged activated partial thromboplastin time and the biological false positive reaction in the syphilis test. These results led us to the further investigation, which revealed the presence of high titers of anticardiolipin antibodies. Since this girl presented no extra-renal symptoms of systemic lupus erythematosus (SLE) and had negative serologic tests for SLE, we hypothesize that her nephritis is closely related to antiphospholipid antibodies.

Antibodies, Antiphospholipid↗
PubMed2000

Nonoperative treatment of reperforated duodenal ulcer: report of three cases.

During the period between 1983 and 1998, a total of 58 patients were admitted to the surgical department of Akita Red Cross Hospital with acute duodenal perforation. Of these 58 patients, 16 were treated operatively and 42 were treated nonoperatively. Among the 38 men and 4 women who received nonoperative treatment, 3 developed reperforation. The incidence of reperforation was 7.1% and the mean average interval from the initial treatment until reperforation was 3.5 years. Endoscopic biopsy and/or serum anti-H. pylori IgG measurement revealed Helicobacter pylori infection in all three patients. No serious complications developed during the nonoperative treatment of reperforation in these three patients, and their recovery was uneventful. The hospital stay ranged from 10 to 18 days, with a mean stay of 12 days after the first perforation and from 14 to 18 days, with a mean stay of 15.6 days after the reperforation. Nonoperative treatment proved successful as a life-saving procedure for reperforation of a duodenal ulcer in all three patients.

Adult↗