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Biomedical subjects

M Nakagaki

Publications and source records attributed to M Nakagaki.

At least 19 recordsLinked to original sources
PubMed1992

Monolayer-bilayer equilibrium of phospholipid: stabilization of neutral lipid droplets in aqueous medium and catabolism of plasma lipoproteins.

Phospholipid spreads as monolayer at air/water and oil/water interfaces. Interfacial pressure of the monolayer in equilibrium with a definite bulk phase of the lipid, (equilibrium) spreading pressure, depends on lyotropic and thermotropic polymorphic state of the lipid bulk phase. Phosphatidylcholine (PC) in hydrated liquid crystalline state (bilayers in L alpha state) gives an appreciably large value of spreading pressure, 45-46 mN/m. Monolayer-bilayer equilibrium of a neutral lipid-phospholipid mixture is determined by miscibilities of the lipids in mixed monolayer, PC bilayer and bulk (liquid or solid) phase of the neutral lipid. A neutral lipid of limited solubility in PC bilayer forms a separate phase in aqueous medium. The phase is stabilized as small particles in the medium by PC monolayer at the particle surface. The monolayer is in equilibrium with the bilayer. This sort of equilibrium plays important roles in formation and catabolism of triglyceride- and cholesteryl ester-rich lipoprotein particles in animal plasma. The equilibrium is a critical factor also in stabilization of aqueous dispersion of lipophilic vitamin (neutral lipid). Coexistence of emulsion particles (neutral lipid core covered with PC monolayer) and vesicles made of PC bilayer are observed in a stable dispersion.

Animals↗
PubMed1992

Structural analysis on the single-stranded genomic DNAs of the virus newly isolated from silkworm: the DNA molecules share a common terminal sequence.

Recently, a parvo-like virus was newly isolated from silkworm larvae and the two viral DNAs (VD1 and VD2) with different electro-mobilities were identified. We cloned the viral DNAs in a plasmid pUC119 and demonstrated that these two DNAs were not a bimorphic molecules though they shared a common terminal sequence of 53 nucleotides. In addition, the sequence at the 5' terminus of each strand of the viral DNA was located in inverted form at its 3' terminus. On the other hand, the nucleotide sequences of VD1 and VD2 were different from that of the Bombyx densovirus (Ina isolate) DNA.

Animals↗
PubMed1992

Permeability of insulin entrapped in liposome through the nasal mucosa of rabbits.

The permeability of liposome entrapping insulin through the nasal mucosa of rabbit has been studied and compared with the permeability of insulin solution with or without pretreatment by sodium glycocholate (GC). Insulin entrapped in liposome was not detected in the receiver cell using the diffusion cells with the nasal mucosa. On the other hand, permeability of insulin entrapped in liposome increased after the pretreatment of GC. The phospholipids which result from liposomes, were not observed in the receiver. Also, the GC remaining in the nasal mucosa was measured. Considering the mechanism of permeation of insulin entrapped in liposome through the nasal mucosa, the GC remaining in the nasal mucosa may cause the lysis of liposomes.

Administration, Intranasal↗
PubMed1991

[Intestinal T-cell lymphoma (so-called malignant histiocytosis of the intestine) complicated by multiple perforations].

We describe a case of intestinal T-cell lymphoma which was histologically diagnosed of malignant histiocytosis of the intestine. A 47-year-old man was admitted to our hospital because of fever and generalized lymphadenopathy. Mild anemia, leukocytosis, positive CRP and a high level of LDH were noted. Pathological finding of the lymph node was compatible with dermatopathic lymphadenopathy with a slight increase in atypical lymphoid cells. At the 14th day after admission, he suffered from abdominal pain and was diagnosed as having perforative peritonitis. In laparotomy, the infiltration of histiocyte-like atypical cells were found around a site of small perforation of the terminal ileum. The findings were compatible with that of malignant histiocytosis of the intestine (MHI). He had recurrent perforations of the small intestine and died of peritonitis and sepsis at the 42nd day. Southern blot analysis of the biopsied lymph node showed TCR-beta gene rearrangement. Some patients diagnosed clinically and pathologically as having MHI may have a T-cell lymphoma like our case.

Histiocytic Sarcoma↗
PubMed1991

Partial characterization of Fusobacterium necrophorum protease.

Partial characterization of Fusobacterium necrophorum protease was investigated. The protease was partially purified by gel filtration with Toyopearl HW 55. The final preparation was inactivated completely by heating at 60 degrees C for 30 min and inhibited by ascorbic acid, sodium thioglycollate and p-hydromercuribenzoate. Antibody response to the protease was demonstrated in mice receiving 10(4) CFU of F. necrophorum.

Antibodies, Bacterial↗
PubMed1989

Factors affecting the bioadhesive property of tablets consisting of hydroxypropyl cellulose and carboxyvinyl polymer.

The bioadhesive property of tablets consisting of hydroxypropyl cellulose (HPC) and carboxyvinyl polymer (CP) was investigated using the mouse peritoneal membrane. The adhesion force was significantly affected by the mixing ratio of HPC and CP in the tablet, and the weakest adhesion force was observed at the ratio of 3:2 (HPC:CP). Interpolymer complex formation was confirmed between HPC and CP in the acidic medium by turbidity and viscosity measurements. The interaction between CP carboxyl groups and HPC molecules was considered to be a possible mechanism for this complex formation on the basis of a Fourier-transform infrared spectroscopy. These observations suggested that the adhesion force of the HPC--CP tablet to the mucous membrane was significantly affected by the interpolymer complex formation between HPC and CP.

Acrylic Resins↗
PubMed1989

Decrease in the solubility product of hydroxyapatite by the adsorption of surface-active ion.

The solubility product (Ksp) of hydroxyapatite (HAP) in ionic surfactant solutions decreased with an increase in the adsorbed amount of the surface-active ions (dodecylammonium and dodecyl sulfate ions). In the presence of nonionic surfactant (polyoxyethylene(10) octylphenyl ether), Ksp was almost constant within the limit of experimental error. It was concluded that the decrease in Ksp is due to the decrease in the chemical potential of HAP through the adsorption of the surface-active ion on HAP, and due to the spontaneous change in the constituent ions of the HAP surface (i.e., surface complex formation) by ion-exchange with the surface-active ion.

Adsorption↗
PubMed1986

Effects of lysophosphatidylcholine micelle and phosphatidylcholine liposome on photoreduction of methylviologen.

Photoinduced reduction of methylviologen (MV2+) by ethylenediaminetetraacetate (EDTA3-), which was sensitized by thiacarbocyanine dyes having long alkyl chains (C+m-n) embedded in palmitoyl lysophosphatidylcholine micelle and dipalmitoyl phosphatidylcholine liposomal membrane, was carried out. The formation rate of reduced methylviologen cation radical (MV+.) decreased with the time of irradiation with visible light, and the deceleration was more pronounced in the micellar solution. In kinetic studies, we found that the sensitizer divalent cation radical (C2+.m-n) is formed through the reaction of photoexcited sensitizer (C+*m-n) with MV2+ as an intermediate in this reaction, and that the reduction of C2+.m-n with EDTA3- inhibits the back reaction of MV+. with C2+.m-n. The inhibition was greater in the liposomal solution than in the micellar solution. This was ascribed to a higher concentration of EDTA3- on the liposomal surfaces through the electrostatic interaction between EDTA3- and the liposomal surfaces, the charge of which is attributed to the univalent cation sensitizer embedded in the liposomal membrane. The difference in the positive charge density of the surface of these lipid aggregates was due to the difference in the curvature of the micelle and the liposome. These results suggest that the dipalmitoyl phosphatidylcholine liposome is a more effective carrier than the palmitoyl lysophosphatidylcholine micelle for the production of MV+. in the photoreduction studied here.

Edetic Acid↗
PubMed1985

Interaction of differently oriented lipids in monolayer: mixed monolayers of 16-(9-anthroyloxy)palmitic acid with phosphatidylcholine and cholesterol.

16-(9-Anthroyloxy)palmitic acid (16-AP) is a bifunctional molecule with carboxyl and 9-anthroyloxy groups attached at both ends of the hydrocarbon chain. At the air-water interface, in a monolayer, the 16-AP molecule has horizontal and vertical orientations, depending on the surface pressure of the monolayer. The miscibilities of 16-AP with dimyristoylphosphatidylcholine (DMPC), cholesterol (CH), and fatty acids in mixed monolayers were evaluated in investigations of monolayer phase transitions. Lipid molecules with flexible hydrocarbon chains, i.e., DMPC and fatty acids, formed homogeneous mixed monolayers with horizontally oriented 16-AP. On the other hand, the rigid molecule, CH, could not accommodate the horizontally oriented 16-AP in a monolayer, and there was a phase separation from 16-AP. In biological and reconstituted membranes, preferential binding of phospholipid to the integral protein and exclusion of cholesterol in close vicinity of the membrane protein have been recognized. On the basis of this work, it can be expected that flexible lipids readily accommodate the rough hydrophobic surface of integral proteins and stabilize the structure of the protein, while rigid lipids such as cholesterol are removed from the immediate environment of the membrane protein, if the protein does not interact specifically with the rigid lipids.

Calorimetry↗