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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 217 records · Page 12Linked to original sources

A one-step sandwich enzyme immunoassay for human matrix metalloproteinase 2 (72-kDa gelatinase/type IV collagenase) using monoclonal antibodies.

A one-step sandwich enzyme immunoassay (EIA) for human matrix metalloproteinase 2 (MMP-2, 72-kDa gelatinase/type IV collagenase, EC 3.4.24.24) was established with a pair of monoclonal antibodies prepared against the precursor form of MMP-2 (proMMP-2) purified from the conditioned medium of human skin fibroblasts or against a synthetic peptide corresponding to the N-terminal domain of proMMP-2. ProMMP-2 in samples was allowed to simultaneously react with both solid-phase and peroxidase-labeled antibodies. Sensitivity of this EIA system was 2.4 pg/assay (0.24 microgram/l) and linearity was obtained between 10 and 5,000 pg/assay (1.0-500 micrograms/l). The EIA system recognized both the free form of proMMP-2 and its complex form with TIMP-2 with the same degree of immunoreactivity. ProMMP-2 levels in human sera from patients in various disease states were analyzed. In sera from patients with hyperthyroidism (12), primary biliary cirrhosis (8) and hepatocellular carcinoma (11), 749 +/- 166, 716 +/- 135 and 686 +/- 236 micrograms/l of proMMP-2 were detected, respectively and these were significantly higher than that observed in 213 normal human sera (570 +/- 118 micrograms/l). In contrast, the levels in sera from 33 patients with osteoarthritis (449 +/- 72 micrograms/l), 45 with rheumatoid arthritis (408 +/- 139 micrograms/l), 13 with stomach cancer (427 +/- 103 micrograms/l) and 10 with pancreatic cancer (422 +/- 130 micrograms/l) were significantly lower than that found in normal sera. Immunoblot and gel filtration analyses showed that human sera contain several MMP-2 species in addition to proMMP-2 which exist in a complex form with TIMP-2.

Amino Acid Sequence↗

A one-step sandwich enzyme immunoassay for tissue inhibitor of metalloproteinases-2 using monoclonal antibodies.

A one-step sandwich enzyme immunoassay system was developed with a pair of monoclonal antibodies against two individual oligopeptides prepared from the amino acid sequence of the human tissue inhibitor of metalloproteinases-2 (TIMP-2). The assay system consisting of two simultaneous immunoreactions used a solid phase monoclonal antibody and a horse-radish peroxidase-labeled monoclonal antibody. The system detected a free form of TIMP-2 and that complexed with active forms of matrix metalloproteinases (MMPs) giving a different sensitivity for each MMP but not TIMP-2 complexed with the precursor of 72 kDa gelatinase/type IV collagenase (MMP-2). The sensitivity of the system was 1.6 microgram/l (16 pg/assay) and linearity was obtained between 6.3 and 50 micrograms/l (63-500 pg/assay). TIMP-2 levels in the sera of 20 patients with rheumatoid arthritis (68 +/- 25 micrograms/l, mean +/- S.D.) and 13 patients with hepatocellular carcinoma (76 +/- 46 micrograms/l) were significantly higher (P < 0.05) than those of 18 normal subjects (5.6 +/- 7.4 micrograms/l). In contrast, the levels in the sera of 10 patients with gastric cancer (45 +/- 18 micrograms/l) and 7 patients with cancer of the uterus (36 +/- 13 micrograms/l) were significantly lower (P < 0.05 or P < 0.01) than those of normal subjects. Immunoreactivity analyses suggested that the precursor of MMP-2 in normal sera exists in a complexed form with TIMP-2 by interacting with the C-terminal domain of TIMP-2.

Amino Acid Sequence↗

A one-step sandwich enzyme immunoassay for human matrix metalloproteinase 1 (interstitial collagenase) using monoclonal antibodies.

Interstitial collagenase (EC 3.4.24.7, matrix metalloproteinase-1, MMP-1) is synthesized and secreted by many cells, and plays an important role in a wide variety of pathophysiological degradation processes of extracellular matrices. The activity of MMP-1 is regulated by tissue inhibitors of metalloproteinases, TIMP-1 or TIMP-2, which form a non-covalent complex with the active enzyme. We raised monoclonal antibodies against zymogen of MMP-1, proMMP-1 purified from human skin fibroblasts. The antibodies recognized both precursor and active forms of MMP-1, but did not cross-react with 72-kDa and 92-kDa gelatinase/type IV collagenases or stromelysin-1. A specific and sensitive one-step sandwich enzyme immunoassay for human MMP-1 was developed using a solid phase monoclonal antibody and a horseradish peroxidase-labeled monoclonal antibody (Fab'). The assay can be completed within 1 h (30 min for immunoreaction and 15 min for color development) and the sensitivity is 0.12 microgram/l with the linearity between 0.12 and 10 micrograms/l. Active MMP-1 shows 1.3-fold higher absorption at 492 nm than proMMP-1. However, the recognition rate of MMP-1 is decreased to approximately 50% and < 3% for the MMP-1-TIMP-1 and MMP-1-TIMP-2 complex forms, respectively. The MMP-1 levels in human sera from 120 healthy subjects are shown to be in the range of 8.5 +/- 5.2 micrograms/l (mean +/- S.D.) and the levels of 95% of the samples range from 0 to 20 micrograms/l.

Amino Acid Sequence↗

Membrane cofactor protein (CD46) protects cells predominantly from alternative complement pathway-mediated C3-fragment deposition and cytolysis.

Membrane cofactor protein (MCP) cDNA was transfected into Chinese hamster ovarian tumor (CHO) cells and the functional properties of the expressed protein were studied. Cells adherent to flasks were essential for continuous expression of MCP on CHO cells. If the cells were maintained in noncoated flasks, MCP expression was markedly reduced but upon being transferred to coated flasks reexpressed the protein. MCP expressed on CHO cells had the expected m.w., approximately 50 kDa, and possessed factor I-cofactor activity. By a propidium iodide incorporation assay and by 51Cr release assay, antibody-sensitized CHO cells expressing MCP were protected from C-mediated cytotoxicity. The inhibition of lytic activity correlated with a decrease in C3 deposition. This host cell protective activity was exerted efficiently for the alternative pathway. The classical pathway was not blocked by MCP unless the cells were presensitized with low concentrations of antibody. These results imply that MCP primarily protects host cells from alternative pathway-mediated C3 targeting. In a pathologic state such as autoimmune diseases, the binding of an autoantibody to a target may overcome this protective effect of MCP via the classical pathway.

Animals↗

Response properties of primary somatosensory cortical neurons responsive to cold stimulation of the facial skin and oral mucous membrane.

The distribution and response characteristics of the primary somatosensory cortical (SI) neurons activated by cold stimulation of the facial skin and oral mucous membrane were studied in cats. The discharge activities of 53 cold-sensitive SI neurons that responded to a decrease in temperature of the facial skin and/or oral mucous membrane were recorded. Each of these neurons was classified according to its responsiveness to mechanical stimulation as follows: LTM (low-threshold mechanoreceptive, 14/53), WDR (wide dynamic range, 39/53) and NS (nociceptive-specific, none identified). Encoding and non-encoding SI cold-sensitive neurons were identified, according to their responsiveness to decremental thermal stimulation. Only 14 cold-sensitive SI neurons demonstrated increased firing frequencies when subjected to incremental stimulus intensity increases and were classified as the encoding-type, whereas 39 non-encoding-type neurons did not.

Animals↗

B16-G4F mouse melanoma cells: an MSH receptor-deficient cell clone.

The two mouse melanoma cell lines B16-F1 and B16-G4F retain their melanogenic capacity when cultured in vitro. Melanotropic peptides such as alpha-melanocyte-stimulating hormone (alpha-MSH) induce formation and release of melanin pigment in B16-F1 cells. In contrast, B16-G4F cells do not respond to alpha-MSH. Using receptor-binding analysis and photoaffinity crosslinking we demonstrate that the lack of response of B16-G4F cells to alpha-MSH is due to the absence of functional MSH receptors from the cell surface. Northern blot analysis of receptor mRNA revealed that MSH receptor mRNA is not expressed in B16-G4F cells. These cells represent a new tool for the study of signal pathways related to the control of melanogenesis in melanoma cells.

Animals↗

Effects of a novel thyrotropin-releasing hormone analogue, JTP-2942, on extracellular acetylcholine and choline levels in the rat frontal cortex and hippocampus.

The effects of a novel thyrotropin-releasing hormone (TRH) analogue, N alpha-[(1S,2R)-2-methyl-4-oxocyclopentanecarbonyl]-L-histidyl-L-pr olinamide (JTP-2942) on acetylcholine (ACh) release and on the extracellular choline level were investigated in rat frontal cortex and hippocampus by microdialysis, and were compared with effects of TRH. JTP-2942 (0.3 mg/kg i.p.) produced a marked (> 300%) and persistent increase of ACh release in both the frontal cortex and hippocampus, while TRH (3 mg/kg i.p.) caused a significant but transient increase of ACh to about 200% in the frontal cortex. Both drugs significantly decreased the choline levels in both brain regions. Investigation of the effects of JTP-2942 (0.001-1 mM) and TRH (1 and 10 mM) on ACh release and choline levels when perfused through the dialysis probe revealed that JTP-2942 had a greater effect than TRH in both the frontal cortex and the hippocampus. The action of JTP-2942 was about 1000-fold more potent than that of TRH in both brain regions. Oral administration of JTP-2942 at a dose of 10 mg/kg markedly and persistently increased the release of ACh and at doses of 1-10 mg/kg decreased the extracellular choline level in the frontal cortex and hippocampus. These results also suggest that JTP-2942 has some selectivity for the hippocampus compared to the frontal cortex after both systemic administration and local injection. The increase of ACh release caused by JTP-2942 was completely antagonized by perfusion with tetrodotoxin (TTX, 1 microM), suggesting that the action of JTP-2942 on cholinergic neurons was mediated via neuronal activity.

Acetylcholine↗

Addition of serum from patients with collagen diseases increases to cultured human endothelial cells production and release of von Willebrand factor.

The addition of sera from patients with collagen diseases, particularly those with vascular complications, to the supernatant of cultured vascular endothelial cells (EC) in vitro significantly increased the surface and intracellular amounts of von Willebrand factor antigen (vWF:Ag) compared with results obtained with sera from normal healthy subjects. Peak levels of vWF:Ag occurred after 24 h of in vitro culture. Moreover, the amounts of vWF:Ag secreted into the EC supernatant with patient serum added were significantly higher than the amounts secreted into EC supernatant with control serum added, even after 48 h of in vitro culture. Levels of large and intermediate multimers (LIM) of von Willebrand factor (vWF) increased in EC supernatant exposed to serum from patients with collagen diseases as compared with levels in supernatant exposed to serum from normal controls, whereas no significant differences were detected overall between adding the plasma of patients and of normal subjects. In addition, C-reactive protein (CRP) induced a time- and dose-related release of vWF:Ag from EC, while glucocorticoid did not effect the release of vWF:Ag from EC. These results suggest that the sera of patients with collagen diseases, particularly those with vascular complications, stimulate the production and release of LIM of vWF from EC.

C-Reactive Protein↗

Nd:YAG laser trabeculopuncture (YLT) for glaucoma with traumatic angle recession.

Traumatic angle recession caused by blunt trauma often induces uncontrollable glaucoma despite the maximum medical therapy tolerated, such as argon laser trabeculoplasty (ALT), with no or little benefit. Therefore, instead of ALT, we tried Nd:YAG laser trabeculopuncture (YLT) on 11 patients with this type of glaucoma. The intraocular pressure of these patients was followed up for 15 +/- 7 months (average +/- SD). In 6 of 7 eyes treated initially with YLT, the IOP was significantly reduced, so medication was discontinued. Four other cases with uncontrollable IOP after failed ALT were treated with YLT. The IOP of 3 cases was successfully controlled by medication after YLT. These YLT results were then compared with those of ALT in 11 glaucoma patients with traumatic angle recession. Seven of 11 cases treated initially with ALT failed in less than 3 months, and surgical intervention or additional laser treatments were required. The probability of success from the time-series analysis at 12 months after each laser application was 0.909 in YLT, 0.273 in ALT. YLT offers significant advantages over ALT for the treatment of glaucoma with traumatic angle recession after blunt trauma and thus merits further study.

Adolescent↗

Monoclonal antibodies against two epitopes in the human alpha 1 (IX) collagen chain.

Type IX collagen is a component of cartilage and vitreous humor. Its structure and matrix localization suggest it may serve to mediate interactions between fibrillar collagen, proteoglycan and other matrix components. Consequently, abnormalities in type IX collagen may result in chondrodysplasia. In this paper we describe the preparation and use of two monoclonal antibodies which recognize peptide sequences within the human cartilage alpha 1 (IX) collagen chain. Antibody 23-5D1 is highly sensitive and highly specific. It permits the immunoblot detection of type IX collagen extracted from milligram amounts of normal and chondrodysplastic cartilage; it also identifies the "short" form of the alpha 1 (IX) chain in human vitreous humor. Antibody 37-10H7 is highly specific, but of low sensitivity. It was used to make the new observation that an N-linked oligosaccharide is present in the amino-terminal globular domain of the alpha 1 (IX) chain. We anticipate that these antibodies may be valuable tools in the study of human and other mammalian chondrodysplasias.

Amino Acid Sequence↗

The expression of invasive behavior of differentiated squamous carcinoma cell line evaluated by an in vitro invasion model.

In order to elucidate the factors contributory to the expression of invasiveness of oral squamous cell carcinoma, we conducted biochemical and morphological comparisons of well differentiated squamous carcinoma cell line OSC-19 (oral squamous cell carcinoma) and undifferentiated carcinoma cell line KB, both cultured on 3T3 cell-embedded collagen gel (in vitro invasion model). OSC-19 cells invaded 3T3 cell-embedded collagen gel, while KB cells and OSC-19 cells on 3T3 cell-free gel matrix were less invasive. Cultured OSC-19 cells were characterized by lower proliferating activity, lower secretion of laminin and higher secretion of fibronectin than those of KB cells. Although the basement membrane with deposition of laminin and type IV collagen was formed, it was discontinuous at the invasion front. Gelatin zymography and western blotting showed matrix metalloproteinases (MMP), i.e., 72 kDa gelatinase (MMP-2) and 92 kDa gelatinase (MMP-9). Gelatinolytic activity was assayed, and was higher in OSC-19 cells than in KB cells or OSC-19 cells of the 3T3 cell-free model. By immunohistochemical analysis, MMP-2-positive cells were found scattered in both cell lines without any preferential localization, and the positivity for MMP-9 was localized in the invasion front of OSC-19 cells. These results strongly suggest that the invasiveness of squamous cell carcinoma is well correlated with cell-matrix adhesion by fibronectin and with focal elaboration of metalloproteinases, especially MMP-9, which play a major role in degrading the extracellular matrix components.

3T3 Cells↗

Assessment of body composition measured by bioelectrical impedance in children.

Bioelectrical impedance methods have been found to be a valid and reliable way of estimating per cent body fat (%BF) in adults. We applied them to healthy children and compared them with conventional anthropometry methods. One thousand two hundred and sixteen children participated in this study. Impedance and skinfold thickness were measured, and %BF was estimated using these values. Bodyweight and height were measured, and per cent obesity (%OB) and body mass index (BMI) were obtained. The values of %BF by the bioelectrical impedance method (%BFi) were 8.6 +/- 4.0% in the junior male group, 14.2 +/- 2.8% in the junior female group, 7.9 +/- 4.7% in the senior male group and 16.1 +/- 2.9% in the senior female group. The %BFi correlated strongly with skinfold thickness, %OB and BMI. Thus %BFi correlated strongly with variables from conventional methods. It was concluded that it is a reliable way of assessing lipid storage in children.

Adolescent↗

Conjunctival biopsy in adult form galactosialidosis.

Conjunctival biopsy was performed in two siblings with adult-form galactosialidosis. Electron microscopically, several types of intracytoplasmic inclusion were observed in the fibroblasts in conjunctival stroma, lymphatic capillary endothelial cells, Schwann cells, and epithelial cells. Membrane-bound vesicles with fibrillogranular content were frequently observed, and occasional lamellar structures were noted in these inclusions. Dense granular inclusions and oil droplets were also seen. Dense granular inclusions have not been reported in this disease previously.

Adult↗

Intraocular pressure-dependent progression of visual field loss in advanced primary open-angle glaucoma: a 15-year follow-up.

We studied the relationship between intraocular pressure (IOP) and progression of visual filed loss in 83 eyes of 83 patients with advanced primary open-angle glaucoma (loss of at least one quarter of the visual field on Goldmann perimetry). During the 15-year follow-up study, 71 eyes (86%) showed progression of visual field loss. The mean IOP was significantly lower in eyes that remained stable (13.4 +/- 1.3 mm Hg) than in those that showed progression of visual field loss (19.4 +/- 2.6 mm Hg). These results suggest that it is necessary to reduce IOP to below 15 mm Hg to prevent further progression of visual filed loss in advanced glaucoma.

Adult↗

Intracerebral hemorrhage associated with migrainous headache--a case report.

A case of intracerebral hemorrhage that developed some time after severe headache is reported in a relatively young woman. It is proposed that hemorrhage may also be included among the causes of so-called migraine-related stroke, which has generally been known to result from infarction.

Cerebral Hemorrhage↗