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Masaaki Matsumoto

Publications and source records attributed to Masaaki Matsumoto.

10 recordsLinked to original sources
PubMed2006

Contribution of xanthoma tissue-derived LDL density substances in the transformation of macrophages to foam cells.

BACKGROUND: The source of accumulated lipids in the foam cells of xanthoma is primarily the lipoproteins existing in the lesional dermis. OBJECTIVE: This study was designated to clarify the contribution of low density lipoprotein (LDL) density substances existing in xanthoma tissue to foam cell formation. METHODS: An LDL density fraction was obtained from homogenized rabbit experimental xanthoma tissue. Biochemical and functional characteristics of xanthoma-extracted LDL density substance were examined. The in vivo foam cell-inducing ability of xanthoma-extracted LDL density substance was examined microscopically at the intradermal injection site. RESULTS: Xanthoma-extracted LDL density substance showed more negatively charged mobility on agarose gel electrophoresis than plasma native LDL. A small amount of aggregated material remained at the origin on agarose gel electrophoresis. Xanthoma-extracted LDL density substance contained much higher level of lipid peroxides than native LDL. Mouse peritoneal macrophages internalized xanthoma-extracted LDL density substance extensively and transformed into foam cells by incubation with xanthoma-extracted LDL density substance. Intradermal injection of the xanthoma-extracted LDL density substance induced foam cell infiltration in the skin of a normolipemic rabbit. CONCLUSION: LDL density substances prepared ex vivo from experimental xanthoma tissue contained lipid-protein complexes that have physiochemical properties of oxidized LDL. The lipid-protein complexes were incorporated into foam cells. The substances were considered to contribute to foam cell recruitment during the persistence of xanthoma lesions.

Animals↗
PubMed2006

High-speed observation of the piston effect near the gas-liquid critical point.

We investigated adiabatic changes in a near-critical fluid on acoustic time scales using an ultrasensitive interferometer. A sound emitted by very weak continuous heating caused a stepwise adiabatic change at its front with a density change of order 10(-7) g/cm(3) and a temperature change of order 10(-5) K. Very small heat inputs at a heater produced short acoustic pulses with width of order 10 micros, which were broadened as they moved through the cell and interacted with the boundaries. The pulse broadening became enhanced near the critical point. We also examined theoretically how sounds are emitted from a heater and how applied heat is transformed into mechanical work. Our predictions agree well with our data.

Journal Article↗
PubMed2005

Hyaluronan forms complexes with low density lipoprotein while also inducing foam cell infiltration in the dermis.

BACKGROUND: Xanthoma is a foam cell infiltrating lesion similar to atherosclerosis. Glycosaminoglycans and proteoglycans have long been considered to play a role in atherogenesis. OBJECTIVE: The purpose of this study is to investigate the role of hyaluronan, the main dermal glycosaminoglycan, in xanthoma formation. METHODS: The complex formation of low density lipoprotein (LDL) with hyaluronan was investigated by assaying the cholesterol level of precipitates that were formed by incubating LDL, hyaluronan and cetylpyridinium chloride in the presence of Ca2+. The uptake of LDL by mouse peritoneal macrophages was studied by assaying the cellular cholesterol esterification activity. The responsible receptor for the LDL internalization was examined by saturating hyaluronan receptor and blocking class A macrophage scavenger receptor (CD204). Hyaluronan was injected into the dorsal skin of diet-induced hypercholesterolemic rabbits to reveal the xanthoma inducing activity of hyaluronan. RESULTS: Cetylpyridinium chloride precipitated hyaluronan, which had formed complexes with LDL. The macrophages incorporated hyaluronan-LDL complexes and oxidized LDL via CD204. Foam cell infiltration and cholesterol accumulation were induced by intradermal injections of hyaluronan in diet-induced hypercholesterolemic rabbits. CONCLUSION: Hyaluronan, like other sulfated glycosaminoglycans, retains LDL by forming a complex. Via macrophage scavenger receptors, macrophages incorporate not only LDL-hyaluronan complexes, but also oxidized LDL, which has been oxidized during the retention time.

Animals↗
PubMed2005

IgE- and IgE+Ag-mediated mast cell migration in an autocrine/paracrine fashion.

Mast cells are the major effector cells for immediate hypersensitivity and chronic allergic reactions. These cells accumulate in mucosal tissues of allergic reactions, where immunoglobulin E (IgE) is produced locally. Here we provide evidence that, in addition to antigen that can attract IgE-bound mast cells, the type of IgE molecules that efficiently activate mast cells can promote the migration of mast cells in the absence of antigen. IgE- and IgE+Ag-mediated migration involves an autocrine/paracrine secretion of soluble factors including adenosine, leukotriene B4, and several chemokines. Their secretion depends on 2 tyrosine kinases, Lyn and Syk, and they are agonists of G-protein-coupled receptors and signal through phosphatidylinositol 3-kinase gamma, leading to mast cell migration. In mouse experiments, naive mast cells are attracted to IgE, and IgE-sensitized mast cells are attracted to antigen. Therefore, IgE and antigen are implicated in mast cell accumulation at allergic tissue sites with local high IgE levels.

Animals↗
PubMed2003

Different mechanisms of adhesion molecule expression in human dermal microvascular endothelial cells by xanthoma tissue-mediated and copper-mediated oxidized low density lipoproteins.

BACKGROUND: Oxidation of low density lipoprotein (LDL) has been implicated in infiltration of foam cells derived from circulating monocytes. Monocyte adhesion to endothelial cells and migration into dermis are essential steps for infiltration of foam cells. OBJECTIVE: We investigated the role of adhesion molecules contributing to the process of monocyte adhesion to human dermal microvascular endothelial cells (HDMEC). Special attention was paid to the signal transduction for adhesion molecule expression induced by two distinct types of oxidized LDL. METHODS: HDMEC were incubated with xanthoma tissue-modified LDL (x-LDL), a model of extravasated LDL oxidized in xanthoma lesions, or Cu(2+)-treated LDL (Cu-LDL), a model of oxidized LDL. Adhesion of U937 cells, a human monocytic leukemia cell line, to HDMEC and expression of endothelial cell adhesion molecules on HDMEC were examined. Signal transduction pathways for the adhesion molecule expression were evaluated by employing specific inhibitors. RESULTS: x-LDL induced adhesion of U937 cells to HDMEC through vascular cell adhesion molecule-1 (VCAM-1) and E-selectin by activating tyrosine kinase pathway. Cu-LDL up-regulated the adhesion through not only VCAM-1 and E-selectin but also intercellular cell adhesion molecule-1 (ICAM-1) by activating G(i) protein pathway. CONCLUSION: Extravasated and oxidized LDL in xanthoma lesions contributes to foam cell recruitment by activating tyrosine kinase pathway and inducing adhesion of monocytes to HDMEC through VCAM-1 and E-selectin. Cu-LDL, on the other hand, activates G(i) protein pathway and induces the adhesion through ICAM-1, VCAM-1 and E-selectin.

Cell Adhesion↗
PubMed2002

Increased synthesis of calcitonin gene-related peptide stimulates keratinocyte proliferation in murine UVB-irradiated skin.

Repeated ultraviolet (UV) irradiations have been shown to induce keratinocyte proliferation with acanthosis, stimulate the cutaneous nerve proliferation, and increase the synthesis of calcitonin gene-related peptide (CGRP). In the current study, we examined the role of CGRP in the UVB-induced proliferation of murine keratinocytes. UVB irradiation increased the number of bromodeoxyuridine (BrdU)-labeled basal keratinocytes and caused acanthosis. In addition, CGRP expression was up-regulated in the peripheral nerves of the upper dermis and lower epidermis. Repeated intradermal injections of CGRP increased the number of BrdU-labeled basal cells and caused acanthosis. Intradermal injections of capsaicin prior to UVB-irradiation inhibited the UVB-induced CGRP expression, BrdU labeling in basal keratinocytes and epidermal thickening. Intradermal injections of anti-CGRP antibody inhibited the UVB-induced BrdU labeling in basal keratinocytes, but epidermal thickening was not significantly inhibited. These results indicate that CGRP is one of the stimulators to UVB-induced keratinocyte proliferation. On the other hand, expression of substance P, another neuropeptide in the peripheral nerve, was not up-regulated by UVB irradiation.

Animals↗
PubMed2002

Low density lipoprotein oxidized in xanthoma tissue induces the formation and infiltration of foam cells.

Human low density lipoprotein (LDL) was incubated with rabbit xanthoma tissue or non-lesional dermis. The xanthoma tissue-modified LDL (x-LDL) was oxidized showing a 12-fold higher level of thiobarbituric acid-reactive substances (TBARSs) and a faster anodic electrophoretic mobility than native LDL (n-LDL). The LDL treated with non-lesional dermis (d-LDL) had a twofold higher TBARS level compared with n-LDL, but the electrophoretic mobility of d-LDL and n-LDL was similar. Cholesterol esterifying activity in mouse peritoneal macrophages, an indicator of LDL uptake, was up-regulated 5-fold and 1.8-fold by incubation with x-LDL and d-LDL, respectively, compared with n-LDL. Macrophages transformed into foam cells in incubation with x-LDL, and intradermal injections of x-LDL induced infiltration of great many foam cells in the normolipemic rabbit dermis. d-LDL had much less effects on the foam cell formation and foam cell infiltration than x-LDL. Cholesterol:protein ratio was higher in x-LDL than in n-LDL and d-LDL, suggesting that x-LDL-induced foam cells accumulated the lipids by incorporating the cholesterol-rich x-LDL. In conclusion, extravasated LDL receives oxidation and contributes to foam cell recruitment in xanthoma lesions. On the other hand, extravasated LDL in non-lesional dermis receives limited oxidation and additional promoting factors are necessary for initiation of xanthoma development.

Animals↗
PubMed2002

[A long-term survivor undergoing microwave coagulation therapy for hepatocellular carcinoma located just above the main trunk of right hepatic vein].

A 52-year-old male had hepatocellular carcinoma (HCC), located just above the main trunk of the right hepatic vein. Firstly, this patient was treated by TAE. However, the effect was incomplete, so the patient was referred to Kurashiki Medical Center for additional therapy. Microwave coagulation therapy (MCT) under laparotomy was performed due to the deterioration of hepatic functional reserve. The level of AFP decreased to the normal range. Recurrent HCC was found at medial segment of the liver by MRI taken seven months after the first MCT. MCT was performed again intraoperatively. The main trunk of the right hepatic vein was proved to be patent by enhanced CT. Furthermore, this patient has lived without tumor recurrence for 34 months after the second MCT. This case shows that MCT is a useful method to treat HCC located near the main hepatic vein.

Carcinoma, Hepatocellular↗