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Biomedical subjects

K Yoshikawa

Publications and source records attributed to K Yoshikawa.

At least 199 records · Page 11Linked to original sources
PubMed1999

Hypoxia potentiates ultraviolet A-induced riboflavin cytotoxicity.

Flavins are thought to be important chromophores for chronic photo-induced skin injury, but the mechanism is not well known. We have reported that the primary cytotoxicity remaining in ultraviolet A-irradiated riboflavin solution is attributable to hydrogen peroxide. Because the dermis is more hypoxic than the atmosphere, we investigated the cytotoxicity of riboflavin solution during and after ultraviolet A irradiation under hypoxia. Riboflavin solution showed stronger cytotoxicity during irradiation under hypoxia than under air. Riboflavin solution that had been irradiated under hypoxia at lower ultraviolet A doses showed stronger cytotoxicity and contained more hydrogen peroxide than solution irradiated under air at the same doses. At higher ultraviolet A doses, however, the cytotoxicity and hydrogen peroxide quantity were similar in riboflavin solutions irradiated under different oxygen conditions. The effect of a singlet oxygen quencher, sodium azide, on the induction of cytotoxicity and production of hydrogen peroxide by ultraviolet A irradiation of riboflavin solution was examined. The presence of sodium azide in the solution during ultraviolet A irradiation suppressed the cytotoxicity and hydrogen peroxide production to similar levels at various ultraviolet A doses regardless of oxygen conditions. At the maximum suppression by sodium azide, hydrogen peroxide production decreased to 10% of the unsuppressed production. About 40% of the oxygen molecules of hydrogen peroxide produced was thought to be derived from oxygen dissolved in the riboflavin solution.

Cell Line↗
PubMed1999

Pancreatic endocrine carcinoma with multiple hormone production in a raccoon (Procyon lotor).

A pancreatic endocrine carcinoma with lung metastases was found in a 15-year-old male raccoon. This tumour was characterized by great variation in cell size and production of multiple polypeptide hormones. Endocrine markers expressed by the neoplastic cells were, in descending order of frequency, chromogranin A, pancreatic polypeptide (PP), glucagon, somatostatin and insulin. Co-expression of PP and glucagon, somatostatin or insulin was demonstrated immunohistochemically with consecutive sections, and cells with both glucagon and insulin were also observed. The pattern of co-expression was similar to that in the earliest stages of murine pancreatic development. Amyloid deposits in the islets of Langerhans, which reacted with antibody to islet amyloid polypeptide, were thought to be associated with age.

Animals↗
PubMed1999

Folding transition of long duplex DNA from mammalian cells.

Conformational change in individual giant DNAs from pig liver is studied by use of fluorescence microscopy. With the addition of spermidine (a trivalent amine), each DNA chains undergo abrupt transition from an elongated coiled state into a folded compact state. It is found that the all-or-none characteristics in the folding transition for the mammalian DNA is similar to that in phage DNAs.

Animals↗
PubMed1999

Clinical late phase II trials of MultiHance (Gd-BOPTA) for the magnetic resonance imaging of liver tumors in Japan.

OBJECTIVE: The purpose of the study was to evaluate the safety and efficacy of Gd-BOPTA for liver imaging and to determine the most appropriate clinical dose to administer. METHODS: Gd-BOPTA was administered at a dose of 0.05 (group A), 0.1 (group B), or 0.2 (group C) mmol/kg to 201 patients suspected of having malignant liver tumors who had been referred for magnetic resonance imaging. Dynamic phase images (T1-weighted gradient echo sequences obtained during breath-hold), images obtained within 10 min of Gd-BOPTA injection (spin echo images) and delayed images obtained at 40-120 min after Gd-BOPTA injection (T1-weighted spin echo and gradient echo sequences during breathhold) were acquired. All post-contrast images were compared with pre-contrast images (T1- and T2-weighted sequences) obtained immediately prior to Gd-BOPTA administration. Safety was assessed in terms of the incidence of adverse events. RESULTS: The contrast efficacy for the dynamic study was classified as ( ) in 39.7% (27/68), 55.4% (36/65), and 47.0% (31/66) for groups A, B, and C, respectively. The contrast efficacy within 10 min of the injection was classified as ( ) in 7.6% (5/66), 16.9% (11/65), and 12.5% (8/64) for groups A, B, and C, respectively. The contrast efficacy at 40-120 min post-injection was classified as ( ) in 4.4% (3/68), 21.5% (14/65), and 20.0% (13/65) for groups A, B, and C, respectively with significant differences noted between groups A and B and groups A and C. As regards safety, the overall incidence of adverse reactions was 3.5% (7/199). CONCLUSION: Gd-BOPTA is a safe and efficacious contrast agent for use in both dynamic phase imaging and delayed (40-120 min) static imaging. A dose of 0.1 mmol/kg Gd-BOPTA appears to be the ideal dose for use in liver imaging in Japan.

Adult↗
PubMed1999

Deadtime correction in measurement of fractional renal accumulation of 99Tcm-MAG3.

Fractional renal accumulation of a radiotracer is often used to measure renal function with camera-based methods. We evaluated the effect of deadtime count loss on the calculation of fractional renal accumulation of 99Tcm-mercaptoacetyltriglycine (99Tcm-MAG3). In 15 patients, dynamic renal scintigraphy was performed after the injection of 250 MBq of 99Tcm-MAG3. A reference source was placed on the periphery of the field of view of the gamma camera to monitor the loss of counts in dynamic imaging. The activity in the syringe was also counted with the camera to measure the injected dose, and the deadtime count loss in the syringe was computed from the observed count rate and deadtime in imaging a point source. Fractional renal accumulation, the ratio of renal accumulation on dynamic imaging to the injected dose, was assessed with and without correction for deadtime loss. Fractional renal accumulation was over-estimated by 4.1% with no deadtime correction, when the value after correction for loss in both syringe counts and dynamic imaging was used as a standard. It was underestimated by 4.0% with correction for syringe counts only. The results suggest that correction for count loss only in measuring the injected dose does not lead to a significant improvement in the accuracy of estimating renal function with camera-based methods.

Algorithms↗
PubMed1999

Information operations with an excitable field.

It is well established that a traveling wave can be generated on an excitable field, which is described with a pair of partial differential equations for an activator and inhibitor. In the present paper, we use a numerical simulation to show that the traveling wave, or signaling pulse, can be transmitted from an excitable field to an opposing excitable field via an intervening passive diffusion field in a characteristic manner depending on the spatial geometry of the excitable fields. Using such characteristics, it is possible to design various kinds of logic gates together with a time-sequential memory device. Thus, these functions can perform time-sensitive operations in the absence of any controlling clock. It may be possible to accomplish these computations with excitable fields in an actual system, or to create a "field computer" composed of electronic active and passive units.

Journal Article↗
PubMed1999

Decreased regional cerebral metabolic rate for glucose in systemic lupus erythematosus patients with psychiatric symptoms.

To determine brain functional abnormality in systemic lupus erythematosus (SLE) patients with psychiatric symptoms, we evaluated 12 active SLE patients with or without psychiatric symptoms by means of [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (PET), magnetic resonance imaging and neuropsychological testing. Patients with psychiatric symptoms showed significantly poorer performance in tests which subserved attentional function. The PET study revealed that the psychiatric patients had significantly decreased regional cerebral metabolic rates for glucose in the prefrontal, inferior parietal and anterior cingulate regions. Prefrontal, inferior parietal and anterior cingulate dysfunction may be related to attentional deficits that are involved in various psychiatric symptoms in SLE. PET is an invaluable tool to reveal such brain functional abnormality seen in SLE patients with psychiatric symptoms.

Adolescent↗
PubMed1999

Inhibitor studies of a new antibiotic, korormicin, 2-n-heptyl-4-hydroxyquinoline N-oxide and Ag+ toward the Na+-translocating NADH-quinone reductase from the marine Vibrio alginolyticus.

A new antibiotic, korormicin, isolated from a marine bacterium Pseudoalteromonas sp. F-420, was found to strongly inhibit the respiratory chain-linked Na+-translocating NADH-quinone reductase (NQR) from the marine Vibrio alginolyticus. Similar to 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO), korormicin specifically inhibited the Na+-dependent reaction in the NQR complex that is directly coupled to the extrusion of Na+ from the cells. Both korormicin and HQNO acted as purely noncompetitive inhibitors with regard to Q-1, and the inhibitor constants were estimated to be 82 pM and 0.3 microM, respectively. Mutual exclusiveness of korormicin and HQNO was analyzed by kinetic methods, which indicated that a part of the binding site of korormicin and HQNO overlapped, preventing a simultaneous binding of the two inhibitors to the NQR complex. The site of Ag+ inhibition was the initial reaction of the NQR complex catalyzed by Nqr6 subunit. The time courses of Ag+ inhibition and the release of FAD indicate that the Ag+-denatured Nqr6 subunit gradually releases FAD.

Anti-Bacterial Agents↗
PubMed1999

Pregnane glycosides, gymnepregosides G-Q from the roots of Gymnema alternifolium.

The structural elucidation of eleven new related polyoxypregnane glycosides, gymnepregosides G (1), H (2), I (3), J (4), K (5), L (6), M (7), N (8), O (9), P (10) and Q (11), from the roots of Gymnema alternifolium (Asclepiadaceae) was achieved by a detailed study of 1H- and 13C-NMR spectral data and chemical means. The results obtained for new compounds, 1-11, show that they are (20S)-pregn-6-ene-3 beta,5 alpha,8 beta,12 beta,14 beta,17 beta,20-heptaol 3-O-glycosides, and all the sugars at C-3 are beta(i-->4)-linked. Some of them possess benzoyl, (E)- and (Z)-cin-namoyl, and tigloyl residues as the ester linkages located at C-12 and/or C-20 of the aglycone.

Carbohydrate Sequence↗
PubMed1999

Phlebosclerosis of the colon with positive anti-centromere antibody.

A 56-year-old woman with symptoms of chronic bowel disease presented a peculiar calcification of the mesenteric vein of the ascending to transverse colon on barium enema study. The resected colon was hard and black. Histo-pathologic examinations demonstrated fibrous change of the colon with a calcified and hyaline-deposited mesenteric vein. No cell infiltration was observed. These findings were compatible with phlebosclerosis and also with systemic sclerosis. Positive anti-centromere antibody and Raynaud's phenomenon, hallmarks of a variant systemic sclerosis, the CREST syndrome were observed. We therefore speculated that the pathogenesis of the phlebosclerosis of the colon is related to the CREST syndrome.

Autoantibodies↗
PubMed1999

Distribution of JC virus DNA in peripheral blood lymphocytes of hematological disease cases.

OBJECTIVE: The distribution of JC virus DNA in peripheral blood was surveyed by the polymerase chain reaction using the late genes as markers. RESULTS: Six out of 52 cases of hematological diseases and one systemic lupus erythematosus case out of 17 cases were positive for JCV DNA. After separation into B and T lymphocytes by a cell sorter, JCV DNA was found in both cell types prepared from adult T cell leukemia and PML patients. CONCLUSION: Only 1 or 2 copies of JCV genome were calculated to exist in a cell based on the time course analysis of PCR. Only B lymphocytes and glial brain cells are known to produce nuclear factors which support the growth of the virus. The result that B lymphocytes contained a copy number of JCV genome similar to T lymphocytes suggests that there is some barrier to viral growth in susceptible B lymphocytes, and that the growth of JCV is different from that of other virulent viruses.

Aged↗
PubMed1999

Time trends of incidence for cutaneous melanoma among the Japanese population: an analysis of Osaka Cancer Registry data, 1964-95.

Cutaneous malignant melanoma occurs much less frequently among non-white populations than among white populations. Little is known of the descriptive epidemiology of melanoma among Japanese. We investigated time trends of incidence of invasive cutaneous malignant melanoma using data from the Osaka Cancer Registry (Japan) among 321 men and 313 women diagnosed between 1964-95. Average, annual, age-standardized incidence rates per 1,000,000 population were 2.45 (95% confidence interval (CI): 2.17-2.72) for men and 2.04 (95% CI: 1.81-2.28) for women. The age-standardized rate ratio among men from 1964-71 as a reference was almost constant during the study period, whereas that among women increased up to 1.8 fold (95% CI: 1.25-2.56) in 1980-87 and seems to have reached a plateau recently. Among men, the ratio for head and neck lesions decreased to 0.5 fold (95% CI: 0.26-0.99) in 1988-95. Among women, the ratio for lesions of the extremities steeply increased up to 4.7 fold (95% CI: 2.68-8.35) in 1980-87 from the reference period of 1964-71, whereas a slight increase for trunk lesions and no increase for head and neck lesions were noted during the same period. Possible explanations for the subsite-specific time trends are discussed.

Adolescent↗
PubMed1999

Immunohistochemical staining of DNA topoisomerase IIalpha in human gliomas.

OBJECT: The enzyme DNA topoisomerase IIalpha (Topo IIalpha) was tested as a measure of cell proliferation in gliomas. METHODS: Immunostaining for the Topo IIalpha and for the Ki-67 antigen (MIB-1 antibody) was performed in paraffin-embedded tissue sections obtained from 25 resected human gliomas. Additionally, cultured human glioma cells were subjected to simultaneous flow cytometry to determine Topo IIalpha and DNA content. Using flow cytometric analysis, the authors found that the Topo IIalpha antibody labeled cells in the S, G2, and M phases of the cell cycle and also those in some parts of the G0 and G1 phases. In histological sections, Topo IIalpha showed more distinct staining than MIB-1, particularly in older archival cases. The proliferative indices (PIs) based on cells staining for MIB-1 and Topo IIalpha correlated highly with one another (r = 0.96). The Topo IIalpha PI immunopositivity was seen in 4.07% of cells in the low-grade astrocytoma group, 11.97% in the anaplastic astrocytoma group, and 13.84% in the glioblastoma multiforme group, representing significant differences between low-grade astrocytoma and both anaplastic astrocytoma and glioblastoma. A Topo IIalpha PI less than 5% predicted longer patient survival (p = 0.003). CONCLUSIONS: Immunostaining for Topo IIalpha represents a useful alternative to MIB-1 as a proliferative index in human gliomas.

Adolescent↗
PubMed1999

Erythrocyte P1 group antigen expression in VTEC-associated hemolytic uremic syndrome.

BACKGROUND: The P1 blood group antigen has been postulated as a protective host factor against the development of the verotoxin-associated with hemolytic uremic syndrome (HUS). PATIENTS AND METHODS: In this study the P1 blood group antigen in 59 Japanese children with a past history of hemorrhagic colitis (HC) was scored with a direct agglutination method using a commercial anti P1 antibody. RESULTS: The P1 antigen was positive in 4 (21.1%) of 19 patients with a history of postdiarrheal HUS and in 11 (28.0%) of 40 patients with no history. There were no significant differences in the frequency of the P1 phenotype between the 2 groups (p = 0.629). CONCLUSION: We concluded that the P1 blood group antigen is not a protective factor against the development of HUS from verotoxin-producing Escherichia coli(VTEC)-infected hemorrhagic colitis in Japanese individuals.

Bacterial Toxins↗
PubMed1999

Increased renal retention of 99mTc-methylene diphosphonate after nephron-sparing surgery.

UNLABELLED: Nephron-sparing surgery has become established as an effective treatment for localized renal cell carcinoma when preservation of renal function is necessary. The surgery usually requires temporary renal artery occlusion and may induce ischemic renal damage. In this study, we retrospectively evaluated renal activity on bone scintigraphy after nephron-sparing surgery. METHODS: Eleven patients who underwent nephron-sparing surgery for renal cell carcinoma and had a normal contralateral kidney were studied. A total of 12 bone scintigraphy images with 99mTc-labeled methylene diphosphonate were obtained within 1 y after surgery in these patients to assess skeletal metastasis. Activity in the spared renal parenchyma was compared visually with that in the contralateral normal kidney. RESULTS: The tumor was successfully resected in every patient, and no clinically significant complications occurred. Activity in the spared renal parenchyma was elevated in six of seven examinations performed within 21 d after surgery. In three examinations, the increase in renal activity was heterogeneous, being relatively prominent near the surgical margin. Increased renal activity was not observed on five examinations performed 3 mo or more after surgery. CONCLUSION: Renal retention of bone-seeking agents is elevated in the early period after nephron-sparing surgery, probably as a result of ischemic insult during the surgical procedure. Bone scintigraphy may aid in evaluating the presence and degree of ischemic damage of the spared renal parenchyma.

Adult↗