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Biomedical subjects

M Sato

Publications and source records attributed to M Sato.

At least 19 recordsLinked to original sources

The alpha 3 beta 3 and alpha 1 beta 1 complexes of ATP synthase.

Two catalytic structures of H(+)-motive ATP synthase (Fig. 1), the alpha 3 beta 3 oligomer (M(r) = 319,581) and alpha 1 beta 1 promoter (M(r) = 106,527) (Fig. 2), were isolated using high pressure liquid chromatography (Fig. 3) and polyacrylamide gel electrophoresis (Figs. 4 and 5). These were reconstituted from the alpha and beta subunits of thermophilic F1 (TF1), and the alpha 3 beta 3 oligomer was also crystallized. Common to both F1 and the alpha 3 beta 3 oligomer were the nucleotide specificity, the two Km values, the presence of protomer-oligomer activities, and the one-hit--one-kill phenomenon. A synchrotron experiment on the ATP hydrolysis cycle revealed the dynamic shrinkage and expansion of F1(44) that correspond, respectively, to the ATP-induced association and ADP-induced dissociation of the alpha 3 beta 3 oligomer. The oligomer, like mitochondrial F1 and TF1, exhibited two kinds of ATPase activity: one was cooperative and was inhibited by only one inhibitor per hexamer, and the other was inhibited by three inhibitors per hexamer.

Adenosine Triphosphate

Three-dimensional solution structure of the B domain of staphylococcal protein A: comparisons of the solution and crystal structures.

The three-dimensional solution structure of the recombinant B domain (FB) of staphylococcal protein A, which specifically binds to the Fc portion of immunoglobulin G, was determined by NMR spectroscopy and hybrid distance geometry-dynamical simulated annealing calculations. On the basis of 692 experimental constraints including 587 distance constraints obtained from the nuclear Overhauser effect (NOE), 57 torsion angle (phi, chi 1) constraints, and 48 constraints associated with 24 hydrogen bonds, a total of 10 converged structures of FB were obtained. The atomic root mean square difference among the 10 converged structures is 0.52 +/- 0.10 A for the backbone atoms and 0.98 +/- 0.08 A for all heavy atoms (excluding the N-terminal segment from Thr1 to Glu9 and the C-terminal segment from Gln56 to Ala60, which are partially disordered). FB is composed of a bundle of three alpha-helices, i.e., helix I (Gln10-His19), helix II (Glu25-Asp37), and helix III (Ser42-Ala55). Helix II and helix III are antiparallel to each other, whereas the long axis of helix I is tilted at an angle of about 30 degrees with respect to those of helix II and helix III. Most of the hydrophobic residues of FB are buried in the interior of the bundle of the three helices. It is suggested that the buried hydrophobic residues form a hydrophobic core, contributing to the stability of FB.(ABSTRACT TRUNCATED AT 250 WORDS)

Amides

[A stent therapy for portal tumor thrombi. Use of Dacron sheet covered self expandable metallic stent].

We developed a method of intraportal placement of a covered stent against portal tumor thrombi. Half around a z-stent was covered with a Dacron mesh sheet. In one case with portal tumor thrombi protruding into the main portal branch, the stent was placed percutaneously-transhepatically, through a coaxial introducer. Immediately after the placement, portal vein was dilated and, which was still patent after six months. No complication has been observed.

Carcinoma, Hepatocellular

Involvement of p53 mutation in the development of human salivary gland pleomorphic adenomas.

We examined the status of the p53 mutation, a putative tumor suppressor gene, as well as the expressions of myc and mos oncogene products in human salivary gland pleomorphic adenoma cells in culture derived from four individuals using techniques which enabled selective and favourable growths of tumor cells. Culture techniques empolyed in this study consisted of type I collagen gel-coated dishes and serum-free medium as substrates and growth medium, respectively. Cells grown under above conditions were subjected to the analyses of p53, myc and mos expression. When analyzed by both immunocytochemical staining and immunoblot, mutant forms of p53 specifically detected by PAb240 were observed in three of 4 cases. However, none of the 4 cases expressed myc and mos oncogene products. These results may imply a role for p53 mutation in the development of human salivary gland pleomorphic adenomas.

Adenoma, Pleomorphic

[Development of a moving target aiming system using an ultrasound imaging unit].

We developed an ultrasound imaging unit for gating the irradiation of proton beams or acquiring CT scan data for treatment planning according to the motion of tumors in the abdomen. In proton therapy, it is essential that the maximum region of dose rate distribution in a body always coincide with the volume of the tumor in motion during irradiation. Gated proton bean irradiation based on tumor motion could solve this problem and minimize undesirable dose distribution to normal tissues in the vicinity of the tumor. This device can generate the TTL level signal of time width corresponding to the period that the tumor would be sited in a region determined in advance, to control the various kinds of machines. Results of our preliminary experiment using X-ray irradiation showed that this aiming device was able to make the width of the gated irradiation area coincide with that of the planned area within a difference of about 0.5 mm.

Humans

Mitogen-induced tyrosine-phosphorylated 41- and 43-kDa proteins are family members of extracellular signal-regulated kinases/microtubule-associated protein 2 kinases.

Two antipeptide antibodies, one against the peptide corresponding to residues 307-327 (alpha Y91) and one against the peptide corresponding to the C-terminal portion (alpha C92) of the deduced amino acid sequence of the extracellular signal-regulated kinase 1 (ERK1), precipitated two 41-kDa and/or two 43-kDa phospho-proteins from mitogen-stimulated Swiss 3T3 cells. Electrophoretic mobilities on two-dimensional gels of the immunoprecipitated 41- and 43-kDa phosphoproteins were similar to those of the 41- and 43-kDa cytosol proteins, whose increased tyrosine phosphorylation we and others had originally identified in various mitogen-stimulated cells (Cooper, J. A., Sefton, B. M., and Hunter, T. (1984) Mol. Cell. Biol. 4, 30-37; Kohno, M. (1985) J. Biol. Chem. 260, 1771-1779); phosphopeptide map analysis revealed that they were respectively identical molecules. All those phosphoproteins contained phosphotyrosine, and the more acidic forms contained additional phosphothreonine. Immunoprecipitated 41- and 43-kDa phosphoproteins had serine/threonine kinase activity toward myelin basic protein (MBP) and microtuble-associated protein 2 (MAP2). With the combination of two-dimensional gel electrophoresis and the kinase assay in MBP-containing polyacrylamide gels of the alpha Y91 immunoprecipitates, with or without phosphatase 2A treatment, we showed that only their acidic forms were active. These results clearly indicate that 41- and 43-kDa proteins, the increased tyrosine phosphorylation of which is rapidly and commonly induced by mitogen stimulation of fibroblasts, are family members of ERKs/MAP2 kinases and that phosphorylation both on tyrosine and threonine residues is necessary for their activation.

3T3 Cells

Occurrence of differentiated keratin peptide(K1) in cultured human squamous cell carcinomas.

To date, the largest keratin peptide(K1, 68 KD) has been absent in cultured human squamous cell carcinomas. Using a low salt aqueous solution, not containing high salt and Triton X-100, as a washing buffer for keratin extraction, followed by two dimensional polyacrylamide gel electrophoresis, immunological techniques and Northern blot analysis, we demonstrated K1 peptide in two kinds of cultured human squamous cell carcinomas. Until now keratin extraction has been done using high salt/Triton X-100 solution during which K1 peptide may be removed together developed an affinity with the buffer. Many investigators may have therefore overlooked K1.

Amino Acid Sequence

Regional variability of colonocyte growth and differentiation in the rat.

The location of stem cells and the direction of colonocyte migration in the normal rat colonic crypt were investigated using a serial bromodeoxyuridine (BrdU) and [3H]thymidine labeling protocol. The results demonstrate that in the distal colon the stem cells are located in the crypt base and that cells migrate up toward the luminal surface. In the proximal colon, however, the stem cells are located in the midcrypt, and the colonocytes migrate in two directions, up toward the luminal surface and down toward the crypt base.

Animals

Immunocytochemical and in situ hybridization evidence for the coexistence of GABA and tyrosine hydroxylase in the rat locus ceruleus.

We have demonstrated the coexistence of GABA-like and tyrosine hydroxylase-like immunoreactivities (GABA-LI and TH-LI, respectively) in the same neurons of the rat locus ceruleus (LC). The profiles of these cells were labeled by alternately immunostaining adjacent sections for GABA-LI or TH-LI by the avidin-biotin-peroxidase complex method or the peroxidase-anti-peroxidase method after perfusion (either Zamboni's fixative or PPG), and observation at light and electron microscopic levels. For light microscopy, pairs of adjacent sections of more than 590 (Zamboni's) and 260 (PPG), and for electron microscopy, 40 ultrathin sections cut from adjacent semithin plastic sections (Zamboni's), were examined. GABA-LI was found in 80% (1,309/1,642 in total) of small and medium-sized neurons, uniformly scattered throughout the LC. Observations unequivocally show that the majority of GABA-ergic neurons are also noradrenergic. Several neurons are neither noradrenergic nor GABA-ergic, while other noradrenergic neurons do not show GABA-LI. It is shown that astrocytes, but not oligodendrocytes, contain GABA. In situ hybridization using a probe DNA fragment of the glutamic acid decarboxylase (GAD) cDNA, amplified by the polymerase chain reaction, detected GAD mRNA signals in many neurons throughout the LC, supporting the presence of a GAD/GABA system in the LC. Multiple "classical" transmitters, including GABA, serotonin, and noradrenaline, coexist in many LC neurons and may contribute to its widely diverging projections throughout the entire CNS.

Animals

Experimental study on the indications for barbiturate therapy. Change in haemodynamics and the influence of dopamine.

The effect of barbiturates on the cerebral haemodynamics and the influence of dopamine on barbiturates were investigated using 20 cats, and clinical indication of barbiturate therapy is discussed. Cerebral blood flow, oxygen extraction fraction, and cerebro-vascular resistance as well as physiological variables were evaluated at various concentrations of barbiturates in the blood. Thiamylal caused simultaneous reduction of mean arterial blood pressure and cerebral blood flow. As the disruption of autoregulation proceeded, cerebro-vascular resistance and oxygen extraction fraction increased till the barbiturate-induced coma stage. Furthermore, cerebro-vascular resistance increased much more markedly by the combined use of dopamine. Clinically, our results indicate barbiturates would increase cerebral circulatory disturbances caused by vasospasm following subarachnoid haemorrhage because barbiturates further increase cerebro-vascular resistance. Then again, the combined use of dopamine is not preferable because of deterioration in vasospasm.

Animals

Proliferating cell nuclear antigen expression in normal, preneoplastic, and neoplastic colonic epithelium of the rat.

Expression of the proliferating cell nuclear antigen (PCNA) was examined in normal rat intestinal tissues and in carcinogen-treated nonneoplastic and neoplastic colonic mucosa. In the normal intestine, PCNA expression was confined to the expected region of the proliferative compartment. A strong correlation was observed between PCNA labeling index and both [3H]thymidine labeling index (R = 0.993, P = 0.007) and percent of cells in S phase as determined by flow cytometry (R = 0.982, P = 0.018) and between the location of the maximal staining for PCNA and [3H]thymidine (R = 0.997, P less than 0.05). In animals treated with dimethylhydrazine (DMH), crypt hyperplasia, an increased PCNA labeling index, and shifts in both the region of maximal and the upper extent of PCNA expression were observed during DMH exposure; significant crypt hyperplasia and expansion of the PCNA-positive compartment persisted after completion of DMH injections. The patterns of PCNA expression and bromodeoxyuridine incorporation were similar in DMH-induced tumors. It is concluded that PCNA immunohistochemistry can be used as a reliable marker of the proliferative compartment in both normal and neoplastic colonic mucosa.

1,2-Dimethylhydrazine

Changes in the microstructure of cultured porcine aortic endothelial cells in the early stage after applying a fluid-imposed shear stress.

Time course changes in the cell shape and in the patterns of microfilament distribution were analyzed quantitatively using cultured porcine aortic endothelial cell monolayers before and after a shear flow exposure. Geometrical parameters of the cell and of the microfilament were measured on fluorescent photomicrographs of the cells stained with rhodamine-phalloidin. After the shear flow exposure (20 dyn cm-2, 0-24 h), the endothelial cells on glass were elongated and oriented to the direction of the flow. Under the no-flow condition, F-actin filaments were mainly localized at the periphery of the cell, although some filaments were seen in the more central portion. The angles of the filaments were randomly distributed. After 3 h, the stress fiber-like structure of an F-actin bundle was formed in the central part of the cells, and these filaments were oriented to the direction of the flow. The degree of orientation increased as the time of exposure to shear stress became longer. This change in F-actin preceded cell elongation and orientation; these changes were statistically significant only after 6 h. After 24 h, peripheral filaments were again observed, and the fluorescence intensity of rhodamine-phalloidin-stained cells was enhanced. These findings suggest that the redistribution of F-actin filaments is one of the early cellular responses to the onset of shear stress and that it is one of the most important factors controlling cell elongation and orientation to the direction of the flow.

Actin Cytoskeleton

Stimulatory effects of quinpirole hydrochloride, D2-dopamine receptor agonist, at low concentrations on prolactin release in female rats in vitro.

Dopamine (DA) has dual actions (inhibitory and stimulatory) in the regulation of prolactin (PRL) release, depending on its concentration. To investigate the stimulatory effects of DA, perifused rat anterior pituitary cells were exposed to the highly-specific DA D2 receptor agonist, quinpirole hydrochloride (LY). Very low concentrations of LY (10(-12)-10(-10) M) stimulated PRL release and potentiated thyrotropin-releasing hormone (TRH)-induced PRL release. Higher concentrations of LY did not stimulate. Pretreatment with pertussis toxin (30 ng/ml, 24 h) completely abolished these effects of LY. The D2 receptor antagonist, metoclopramide, also blocked the potentiation by LY of TRH-induced PRL release. These data indicate that very low concentrations of dopamine stimulate PRL release via an interaction with a D2 receptor connected to a pertussis toxin-sensitive G protein.

Animals

Modulating effect of tanshinones on mutagenic activity of Trp-P-1 and benzo[a]pyrene in Salmonella typhimurium.

The modulating effects of the Chinese medicinal plant 'Tan-shen', the radix of Salvia miltiorrhiza Bunge, on the mutagenic activities of Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole) and B(a)P (benzo[a]pyrene) were investigated using Salmonella typhimurium TA98. Ether- and hot water-extracted 'Tan-shen' enhanced both mutagens at low concentrations, but suppressed them at high concentrations. Extracts by ether treatment were more effective than those extracted by hot water. Dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA were isolated from the ether extract by high performance liquid chromatography (HPLC) and were recognized to be the mutagenic modulators. 4 tanshinones enhanced the mutagenicity of Trp-P-1 by 8-24-fold at 20 micrograms/plate and the enhancement was reduced at the higher concentration. Dihydrotanshinone I suppressed Trp-P-1 activity completely at 100 micrograms/plate.

Abietanes

Low ligand binding activities of two distinct types of Fc gamma receptor on guinea-pig peripheral blood polymorphonuclear leukocytes are differentially improved by proteolysis or platelet activating factor.

The expression and ligand binding activity of Fc receptors for IgG (Fc gamma R) on guinea-pig peripheral blood polymorphonuclear leukocytes (blood PMN) have been compared with those on casein-elicited peritoneal PMN (exudate PMN). Both the PMN were found to express two distinct types of Fc gamma R, one specific for IgG1 and IgG2 (Fc gamma 1/gamma 2 R) and the other for IgG2 alone (Fc gamma 2 R), when evaluated by their reactivity to monoclonal antibodies (mAb) directed against each type of Fc gamma R. The surface density of Fc gamma 1/gamma 2 R was not significantly different between the two cell types, whereas exudate PMN expressed five times as many Fc gamma 2 R as blood PMN. Moreover, IgG immune complex (IC) binding activities of both the Fc gamma R on blood PMN were markedly low as compared with those on exudate PMN. In addition, blood PMN could not significantly generate superoxide anion (O2-) when exposed to IC. However, these lower activities were improved by protease treatment of the cells or by incubation with platelet activating factor (PAF). Fc gamma 2 R on blood PMN was found to be sensitive to pronase, whereas Fc gamma 1/gamma 2 R was resistant. Pronase-treated blood PMN showed a marked IC binding activity, though they lacked Fc gamma 2 R. This activity was completely blocked by anti-Fc gamma 1/gamma 2 R mAb, indicating that the proteolysis augments the ligand binding capacity of Fc gamma 1/gamma 2 R. In contrast, PAF was found to specifically modulate Fc gamma 2 R. The Fc gamma 2 R expression was significantly increased within 5 min incubation with PAF, whereas that of Fc gamma 1/gamma 2 R was not affected. The cells also exhibited enhanced IgG2-IC binding and subsequent O2- generating activities. These results indicate that both the Fc gamma R on blood PMN are functionally immature and are converted to exhibit intrinsic activities by proteases and PAF; such changes may occur in vivo during exudation and at inflammatory sites.

Animals

Inhibitory effects of nicotinamide on recombinant human interferon-gamma-induced intercellular adhesion molecule-1 (ICAM-1) and HLA-DR antigen expression on cultured human endothelial cells.

Intercellular adhesion molecule-1 (ICAM-1), HLA-A, B, C and HLA-DR antigen on endothelial cells (EC) play important roles in the development of inflammatory processes in autoimmune disorders. In the present study, we investigated the effect of nicotinamide, an inhibitor of poly(ADP ribose) synthetase, on interferon-gamma (IFN gamma)-induced ICAM-1 and HLA-DR antigen expression on the surface of cultured human umbilical vein endothelial cells, assessed by flow cytometry, and EC proliferation by counting cell numbers and [3H]thymidine incorporation assays. Nicotinamide dose-dependently inhibited the IFN-gamma-induced ICAM-1 and HLA-DR antigen expression, but not HLA-A, B, C antigen expression on cultured EC. Furthermore, nicotinamide significantly inhibited endothelial cell proliferation, as assessed by [3H]thymidine incorporation assay. Our findings suggest that nicotinamide may suppress mononuclear cell infiltration, antigen presentation and angiogenesis in the lesions of autoimmune disorders by reducing both IFN gamma-induced ICAM-1 and HLA-DR antigen expression on EC, and EC proliferation. Therefore, nicotinamide can be used for the treatment and prevention of the development of autoimmune disorders.

Antigens, CD

Co-expression of glycine receptor beta subunit and GABAA receptor gamma subunit mRNA in the rat dorsal root ganglion cells.

We examined the expression of the beta subunit mRNA of the glycine receptor and the gamma subunit mRNA of the GABAA receptor in the rat dorsal root ganglion (DRG) using in situ hybridization histochemistry with oligonucleotide probes. About 44% and 37% of the all DRG neurons were labeled by the probes for glycine receptor beta subunit and GABAA receptor gamma subunit mRNAs. Labeled neurons were mostly large cells that simultaneously expressed both glycine receptor beta subunit and GABAA receptor gamma subunit mRNA as demonstrated using consecutive sections. Thus, we suggest the possibility that both GABA and glycine presynaptically regulate the activity of neurons involved in low-threshold mechanoreception at axo-axonic synapses in the spinal cord.

Animals

Co-expression of the alpha 1 and beta 2 subunit genes of the GABAA receptor in the magnocellular preoptic nucleus.

Co-localization of the alpha 1 and beta 2 subunit mRNAs of the GABAA receptor was examined on serial sections of the rat magnocellular preoptic nucleus using in situ hybridization histochemistry. More than half of the labeled neurons in this nucleus contained both transcripts, while 31.9% and 17.4% of them contained only alpha 1 or beta 2 subunit mRNA, respectively. These results indicate that there may be three GABAA receptor subtypes in this nucleus, with co-localization of the alpha 1 and beta 2 subunits occurring in the most common subtype.

Animals