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Biomedical subjects

M Katayama

Publications and source records attributed to M Katayama.

At least 145 records · Page 8Linked to original sources
PubMed1994

Neuroprotection by glial cells through adult T cell leukemia-derived factor/human thioredoxin (ADF/TRX).

Adult T cell leukemia-derived factor (ADF) is a human homologue of thioredoxin (TRX) with many biological functions and is induced by various stimuli and stress. In the central nervous system (CNS), expression of ADF/TRX occurs in glial cells during ischemia and reperfusion. We showed that ADF/TRX was actively released from U251 astrocytoma cells upon exposure to a low concentration of H2O2. The addition of conditioned medium from H2O2-stimulated U251 cells or recombinant ADF (rADF) to the culture medium promoted the survival of neurons from embryonic mouse cortex and striatum, but the addition of mutant ADF (mADF), which has no reducing activity, did not. In addition to rADF, incubation with two other thiol compounds, 2-mercaptoethanol (2-ME) and N-acetyl-L-cysteine (NAC), also increased the neuronal cell survival rate. In contrast, L-buthionine-(S,R)-sulfoximine (BSO), which inhibited the synthesis of glutathione (GSH), decreased the neuronal cell survival rate. Intracellular GSH was increased by incubation with rADF for 24 h, as it is with 2-ME and NAC. Redox active molecules such as thiol compounds may be survival factors for central neurons in vitro, and this capacity may be supplied by endogenous molecules, such as ADF/TRX and glutathione, under certain pathologic conditions in vivo.

Acetylcysteine↗
PubMed1994

Osteonectin/SPARC regulates cellular secretion rates of fibronectin and laminin extracellular matrix proteins.

Osteonectin (OTN) has been implicated in controlling cell adhesivity onto substratum and extracellular matrix (ECM) remodeling. Significant amounts of OTN were synthesized not only by normal fibroblasts and endothelial cells, but also by HT-1080 fibrosarcoma and MG-63 osteosarcoma cells. Levels of secreted OTN were likely to be slightly elevated by the addition of exogenous placental laminin (LN), but not by supplementation of plasma fibronectin (FN). Exogenously supplemented purified bone OTN was not apparently incorporated into the ECM of the adhering cells and had no effect on cell spreading and growth, whereas secretion of type I collagen or FN in the tumor cells was moderately diminished in the presence of soluble OTN. Concentration-dependent down-regulation of cellular LN secretion appeared to be most significant, suggesting that OTN participates in regulating extracellular secretion of ECM components in the cells either with or without the ability to synthesize cellular OTN.

Amino Acid Sequence↗
PubMed1994

Immunoenzymometric analysis for plasma von Willebrand factor degradation in diabetes mellitus using monoclonal antibodies recognizing protease-sensitive sites.

High-molecular-weight von Willebrand factor (vWf) multimers were separated from their smaller multimers by molecular-sieve chromatography and were measured by several sandwich enzyme-linked immunosorbent assays (ELISA) with monoclonal antibodies (moABs) against human vWf. The epitopes of these moABs were mapped partially using fragments generated by V-8 protease digests of native vWf. Large multimers were more immunoreactive with the sandwich ELISA using immobilized VW28-1 and enzyme-labeled VW92-3 than with any other ELISA. The epitopes recognized by these two moABs were sensitive to trypsin and plasmin digestion, and the other moABs appeared to be reactive with the extensively digested antigen. Relative reactivities of this ELISA to plasma vWf multimers in diabetes mellitus were significantly reduced compared to those in healthy subjects. These data demonstrate that molecular abnormalities of vWf circulating in diabetic patients may be caused by some plasma proteases that increase in the microcirculation of patients with diabetic vascular diseases.

Adult↗
PubMed1994

Nitric oxide-related inhibition of carotid chemosensory nerve activity in the cat.

The hypothesis that endogenous nitric oxide may play a physiological role in the regulation of carotid chemosensory activity was tested in this study. The nitric oxide synthase (NOS) inhibitors, L-nitro-arginine-methyl ester (L-NAME, 25-200 microM) and NG-monomethyl-L-arginine acetate (L-NMMA, 50 and 100 microM) were used to study its effects on the chemosensory activity of perfused and superfused cat carotid bodies (n = 21) in vitro at 37-37 degrees C. L-NAME elicited slow excitation of the sensory activity as did L-NMMA. The peak-response was dose-dependent, and approached saturation around 200 microM. The excitation by L-NAME showed the following characteristics (mean +/- SEM): latency of response, 2.2 min +/- 0.3 min; time to peak response, 5.5 min +/- 1.0 min and the peak response increased to 407 +/- 42 imp/sec from 88 +/- 13 imp/sec. The peak response was significantly different (P < 0.05) from the baseline activity. L-arginine (50-500 microM) only briefly reversed the stimulation. Hypoxia enhanced the excitation by L-NAME. On the other hand, sodium nitroprusside (SNP, 0.5-10 microM) which supplies NO, terminated the excitatory effect of L-NAME. The results provide evidence in favor of an inhibitory role of endogenous NO in the carotid body, and exogenous application of NO confirms the inhibitory effect.

Amino Acid Oxidoreductases↗
PubMed1994

Soluble E-cadherin fragments increased in circulation of cancer patients.

Monoclonal antibodies were raised against human placental soluble E-cadherins and used in an immunoenzymometric assay to detect soluble E-cadherins in biological fluids. The E-cadherin assay was accurate enough to quantitate the concentration of soluble E-cadherin in the cell culture supernatants. Immunoreactive E-cadherins, identified as existing in the soluble form in normal serum, were shown to have apparent lower molecular mass (approximately 80 kDa) than intact molecules of E-cadherin. We found that the immunoreactive E-cadherin levels in the serum of the studied cancer patients were significantly elevated (mean +/- s.d. 3.80 +/- 2.36 micrograms ml-1, P < 0.0001) when compared with the normal levels (1.99 +/- 0.50 micrograms ml-1). We also found that serum E-cadherin levels in the 22 patients with gastric cancer (3.51 +/- 1.78 micrograms ml-1, P < 0.02) or the 11 patients with hepatocellular cancer (5.55 +/- 3.11 micrograms ml-1, P < 0.001) were significantly higher than those in the 26 diabetic patients (2.33 +/- 1.58 micrograms ml-1). Of the 54 cancer patients, 53.7% exhibited an elevated amount of soluble E-cadherin in serum. Thus, it is evident that soluble E-cadherin in circulation can be used as a prospective tumour marker that accurately reflects the progressive regeneration of E-cadherin at tumour sites, potentially induced by tumour-associated proteolytic degradation.

Adult↗
PubMed1994

Expression of recombinant mouse/human chimeric antibody specific to human GMP-140/P-selectin.

To construct a mouse/human chimeric antibody, we cloned the genomic DNAs for Ig from a murine hybridoma that produces PL7-6 monoclonal antibody specific to human P-selectin and expressed them in SP2/0 myelomas using a series of pSV2 vectors. Transfected cells that produce the mouse/human chimeric anti-human P-selectin antibody were geneticin-selected and screened by an immunoassay using immobilized antigen. The chimeric antibody, cPL-2R1, expressed by the resultant clone has the murine Ig variable region and the human Ig constant region. The native antibody PL7-6 and the chimeric antibody cPL-2R1 react equally with purified P-selectin and thrombin-stimulated platelets. Competitive inhibition tests demonstrated that the native antibody PL7-6 and the chimeric antibody cPL-2R1 had identical affinity for purified human P-selectin. Thus, although human IgG1 constant region was substituted for the murine counterpart in this chimeric antibody, its specificity and binding affinity for P-selectin was not altered. This chimeric antibody may prove useful when employed in combination with imaging reagents or therapeutic drugs for targeting activated platelets or endothelium in patients with thrombosis or intravascular inflammation.

Amino Acid Sequence↗
PubMed1994

Alternative treatment may lower the need for use of extracorporeal membrane oxygenation.

Access to artificial surfactant and high frequency oscillatory ventilation (HFO) in Japan seems to affect the actual indications for extracorporeal membrane oxygenation (ECMO). The relation between the methods of treatment and survival and/or neurological sequelae of 27 neonates with severe respiratory failure who would have met the US ECMO entry criteria in the Neonatal Intensive Care Unit of National Children's Hospital, Tokyo between January 1988 and May 1992 were retrospectively analyzed. Out of 27 neonates, conventional treatment including artificial surfactant was successful in 6 cases (22%). High frequency oscillatory ventilation was used for the 21 cases who did not respond to conventional treatment and it was effective in 5 cases (19% of total). Extracorporeal membrane oxygenation was used on 11 (40% of total) of 16 cases who did not respond to HFO. Eight (29% of total or 73% of ECMO cases) of these cases survived and 3 cases (11% of total) died. The remaining 5 cases (19% of total) who met the exclusion criteria of ECMO died. No patient with respiratory distress syndrome (RDS) became ill enough to meet the US ECMO entry criteria. Six out of 8 congenital diaphragmatic hernia cases were saved on a delayed surgery protocol with HFO. Only about 1% of the neonates who were admitted to our NICU during the last 4 years needed ECMO treatment. Forty-one per cent of the patients who would have met the US ECMO entry criteria were treated successfully without ECMO. The necessity for ECMO is less in Japan than in the US because other methods can often be used successfully to treat severe respiratory disorders.

Extracorporeal Membrane Oxygenation↗
PubMed1994

[Thyroid scintigraphy in patients with thyroid tumors using 99mTc-hexakis 2-methoxy isobutyl isonitrile].

Early and delayed thyroid scintigraphy with 99mTc-hexakis 2-methoxy isobutyl isonitrile (99mTc-MIBI) was performed in 18 patients with thyroid tumor, including 8 with papillary carcinoma, 1 each with follicular carcinoma, anaplastic carcinoma, and malignant lymphoma, and 7 with thyroid adenoma. Scintigrams obtained were compared with those taken with other radionuclides. In all 11 patients with malignant tumors, increased 99mTc-MIBI uptake was noted in the tumors on early images, although anaplastic carcinoma and malignant lymphoma had mild uptake. On delayed images, 99mTc-MIBI washout was noted in 45.4% (5/11). In one patient with extensive cervical lymph node metastasis, 99mTc-MIBI concentration was evident in the metastatic foci. In the 4 where, the thyroid adenoma consisted mainly of cystic degeneration, a focal defect was noted, but two of the three patients whose thyroid adenoma consisted mainly of a solid component had an intense tracer uptake in the tumors on early and delayed images. In conclusion, there were increased 99mTc-MIBI accumulations in all of the 14 solid thyroid tumors. The quality of 99mTc-MIBI scintigraphic images of thyroid tumors was equal or slightly superior to that taken with 201Tl scintigraphy. 99mTc-MIBI thyroid scintigraphy may be useful in detecting a solid thyroid tumor and its metastasis, although it cannot be used to differentiate between benign and malignant tumors.

Adenocarcinoma, Follicular↗
PubMed1994

[Differential diagnosis between osseous metastasis and degenerative joint disease of the vertebrae by bone SPECT: analysis by accumulation pattern].

To find whether or not bone SPECT can differentiate osseous metastasis from degenerative joint disease (DJD) of the vertebrae, 43 patients with increased vertebral uptake on bone scan, including 25 lesions with bone metastasis, 24 with DJD, and 4 with compression fractures due to osteoporosis, underwent bone planar scanning and SPECT. Increased accumulation in the vertebral lesions on bone SPECT transaxial images was classified into five accumulation patterns; mosaic, large hot, diffuse, peripheral and articular pattern. Mosaic, large hot and diffuse patterns were more frequently noted in patients with osseous metastasis (82%, 67% and 62%, respectively). On the other hand, 80% of the lesions with peripheral pattern and 70% of those with articular pattern were ascribed to DJD. In conclusion, bone SPECT provided much better anatomic information on the extent of 99mTc-MDP. Differential diagnosis between osseous metastasis and DJD of the vertebrae may be improved by bone SPECT.

Adolescent↗
PubMed1993

Effects of 2-mercaptoethanol on survival and differentiation of fetal mouse brain neurons cultured in vitro.

Effects of 2-mercaptoethanol on primary cultures of fetal mouse brain neurons have been investigated. The addition of 2-mercaptoethanol to the culture medium increased 6- or 200-fold the survival rates of embryonic day-16 murine striatum neurons and day-18 cerebral cortical neurons cultured in serum-free medium, respectively, and also induced neurite outgrowth, particularly being prominent in cortical neurons. Moreover, this drug enhanced trophic activities of the conditioned medium of VR-2g or BIM cells. These findings indicate that 2-mercaptoethanol can support the viability and differentiation of fetal mouse brain neurons.

Animals↗
PubMed1993

Activation of nitric oxide synthase from cultured aortic endothelial cells by phospholipids.

Nitric oxide is a recently discovered biomolecule with a broad range of actions and synthesized by nitric oxide synthases. We investigated effects of lipids on particulate nitric oxide synthase purified from cultured bovine aortic endothelial cells by monitoring the conversion of L-[3H]arginine to L-[3H]citrulline. Phosphatidylcholine, lysophosphatidylcholine, and phosphatidylethanolamine dose-dependently enhanced the enzyme activity up to 3 fold in the presence of Ca2+, calmodulin, NADPH, FAD, and (6R)-5,6,7,8-tetrahydrobiopterin. These phospholipids increased the Vmax of nitric oxide synthase without altering the Km for L-arginine and the affinities for Ca2+ and calmodulin. These findings suggest that phospholipids play an important role in modulating endothelial nitric oxide synthase activity.

Amino Acid Oxidoreductases↗
PubMed1993

Increased fragmentation of urinary fibronectin in cancer patients detected by immunoenzymometric assay using domain-specific monoclonal antibodies.

Monoclonal antibodies (MoAbs) recognizing the distinct domains of human fibronectin had previously been established and they were used to construct several sandwich immunoenzymometric assays (IEMAs) for the structural analysis of fibronectin found in the urine of cancer patients. Urinary fibronectin (UFN) was immunodetectable only with FN12-8 and FN30-8 MoAbs against cell-binding domains and was less reactive with other IEMAs using MoAbs directed to terminal domains, indicating that UFN was almost completely fragmented and consisted mainly of cell-binding regions. The IEMA using MoAbs against cell-binding domains had sufficient immunoreactivities with the antigen fragmented by artificial proteolysis, but these fragments could hardly be detected by other IEMAs. UFN levels were significantly elevated in various cancer patients and extremely elevated in some patients with distant metastasis. It is presumed that UFN fragments which increase in cancer patients are generated by extracellular matrix destruction. Thus UFN levels and the ratio of the fragmented UFN level to the non-fragmented UFN level appear to be informative clinical indicators of tumor malignancy or metastatic ability in cancer patients.

Animals↗
PubMed1993

Determination of estrogens in plasma by high-performance liquid chromatography after pre-column derivatization with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole.

A sensitive method for the determination of estrogens by high-performance liquid chromatography with fluorimetric detection was reported. The estrogens were derivatized with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole to their esters in the presence of 4-piperidinopyridine and 1-isopropyl-3-(3-dimethylaminopropyl)carbodiimide perchlorate. The resulting esters were extracted with a Sep-Pak C18 plus cartridge, and then esters were separated on a Wakosil 5C18 column with water-methanol (10:90, v/v) as the mobile phase. The esters were detected by fluorimetric detection (excitation wavelength = 336 nm, emission wavelength = 440 nm). The within-day relative standards deviations (n = 6) for each estrogen (1.0 ng per 100 microliters of plasma) were 8.7-13.0%, and day-to-day relative standard deviations (n = 6) were 8.3-11.8%. The limits of detection for estrogens (estrone, estradiol, estriol, estetrol, ethynyl-estradiol, 2-hydroxyestradiol, 4-hydroxyestradiol) were 0.1-0.2 pg per 100 microliters of plasma (signal-to-noise ratio 3).

Benzimidazoles↗