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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 1,387 records · Page 77Linked to original sources
PubMed1985

3-Methoxy-4-aminoazobenzene, a selective inducer for a high spin form of cytochrome P-448 in rat liver microsomes.

Treatment of Sprague Dawley rats with 3-methoxy-4-aminoazobenzene (3-MeO-AAB) resulted in striking increase of the activity of hepatic microsomal cytochrome P-450s which could efficiently catalyze the mutagenic activation of hepatocarcinogenic aromatic amines such as a tryptophan-pyrolysate component, Trp P-2, and a glutamic acid-pyrolysate component, Glu P-1. The 3-MeO-AAB-induced cytochrome P-450 (3-MeO-AAB-P-450) was examined for the molecular character by immuno-Western blotting using monoclonal antibody to 3-methylcholanthrene-induced cytochrome P-448 (P-448H; m.w. 54,000).

Animals↗
PubMed1985

Nanosecond fluorescence studies of noncovalent interaction of monomeric and dimeric intercalators with DNA.

The noncovalent interaction of 2-aminodipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2) and its derivatives, which are potent mutagens isolated from L-glutamic acid pyrolysate, with calf thymus DNA was studied by steady-state and nanosecond fluorescence spectroscopies. The fluorescence of these compounds exhibits static quenching by noncovalent interaction with DNA. Fluorescence lifetimes of the free and intercalated states of these compounds were determined to be 9-10 and 0.5-1 ns, respectively. The bisintercalative effect of the dimeric analogue of Glu-P-2, bis(Glu-P-2)spermine (2GP-SP), to DNA was also investigated. This 2GP-SP, which has two Glu-P-2 moieties at each end of spermine, indicates a strong intramolecular interaction exhibiting remarkable quenching of fluorescence spectrum and lifetime (tau = 3.5 ns) in the absence of DNA. In the presence of DNA, however, the 3.5-ns lifetime component of fluorescence disappeared, and a two-exponential decay of fluorescence (t = approximately 10 and 1.5 ns) was observed at a DNA concentration of more than approximately 0.001 mM P, while the solution containing a very dilute DNA concentration (less than or equal to 0.001 mM P) exhibits a three-component decay of fluorescence (1.5, 3.5, and approximately 10 ns). The potent bis intercalation of two moieties in 2GP-SP with an identical DNA molecule was suggested by the DNA-concentration dependence of these fluorescence lifetimes and their intensity.

Animals↗
PubMed1985

Effects of arachidonic acid on the metabolism of eicosapentaenoic acid in washed human platelets.

We examined effects of arachidonic acid (AA) on eicosapentaenoic acid (EPA) metabolism in washed human platelets. Although human platelets had been considered to metabolize scarcely EPA, a simultaneous addition of EPA and AA to washed platelet suspensions stimulated markedly EPA metabolism. In addition, the stimulatory effect was more potent over the formation of thromboxane (TX) B3 than that of 12-hydroxy-5,8,10,14,17-eicosapentaenoic acid (HEPE). The stimulation by AA can be due to AA itself and/or AA metabolites. Indomethacin decreased the stimulatory effect of AA on the HEPE formation, suggesting that cyclooxygenase product(s) of AA stimulated the HEPE formation. Among the metabolites of AA investigated, prostaglandin (PG)G2 and 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid had the stimulatory effect on both TXB2 and HEPE formations, whereas PGH2, PGD2, TXB2 and 12-hydroxy-5, 8,10,14-eicosatetraenoic acid were ineffective.

Arachidonic Acid↗
PubMed1985

Monoclonal antibodies against a high spin form of rat cytochrome P-448.

Ten monoclonal antibodies reactive with a high spin form of rat cytochrome P-448 (P-448-H) were obtained from hybridoma clones established by a fusion between P3X63Ag8.653 mouse myeloma cells and spleen cells of a BALB/c mouse hyperimmunized with the cytochrome. One monoclonal antibody recognized an epitope characteristic for P-448-H. Five monoclonal antibodies were cross-reactive with a low spin form of rat cytochrome P-448, but not with cytochrome P-450. Reactivity of these monoclonal antibodies with microsomes of rats pretreated with drug metabolizing inducers and Western blots of the microsomal cytochrome P-450 components are also demonstrated.

Animals↗
PubMed1985

High concentrations of arachidonic acid induce platelet aggregation and serotonin release independent of prostaglandin endoperoxides and thromboxane A2.

We examined platelet aggregation and serotonin release, induced by less than 60 micro M arachidonic acid, using washed platelet suspensions in the absence of albumin. The concentration of arachidonic acid used did not cause platelet lysis. Platelet responses induced by less than 20 micro M arachidonic acid were inhibited by aspirin, whereas those induced by above 30 micro M arachidonic acid were not inhibited, even by both aspirin and 5,8,11,14-eicosatetraynoic acid. Although phosphatidic acid and 1,2-diacylglycerol increased after the addition of arachidonic acid in aspirin-treated platelets, the amounts were not parallel to platelet aggregation. Oleic, linoleic and linolenic acids also induced platelet responses, while palmitic, stearic and arachidic acids did not. EDTA, dibutyryl cyclic AMP, apyrase and creatine phosphate/creatine phosphokinase brought about almost the same effects in platelet responses induced by the unsaturated fatty acids, other than arachidonic acid, as those induced by 40 micro M arachidonic acid. These results suggest that the mechanism of the actions of more than 30 micro M arachidonic acid on platelets is the same as that of the other unsaturated fatty acids and is independent of prostaglandin endoperoxides, thromboxane A2 and, perhaps, phosphatidic acid and 1,2-diacylglycerol.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1985

Active T-cell receptor genes have intron deoxyribonuclease hypersensitive sites.

The T-cell receptor beta-chain gene has a nuclease hypersensitive site in several kinds of T cells, which does not appear in B cells expressing immunoglobulins. Conversely, the kappa immunoglobulin gene shows a known hypersensitive site at its enhancer element in B cells, as expected, but this site is absent in T cells. As is the case with immunoglobulin genes, the T-cell receptor site lies within the gene, in the intron separating joining and constant region segments. These nuclease hypersensitive DNA configurations in the introns of active T-cell receptor and immunoglobulin genes may arise from control elements that share ancestry but have diverged to the extent that each normally acts only in lymphoid cells which use the proximal gene product.

Animals↗
PubMed1985

Time-dependent inhibition of the cyclooxygenase pathway by 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid.

We examined effects of small dose (1 microM or less) of exogenous 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid (12-HPETE) on the formation of cyclooxygenase products from exogenous arachidonic acid (AA) in washed human platelets. With a simultaneous addition of AA, 12-HPETE did not affect the formation of thromboxane (TX)B2 and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT). However, by being preincubated with platelets before an addition of AA, 0.1 microM or greater of 12-HPETE inhibited the formation of TXB2 and HHT dose-dependently. In addition, the inhibitory effect of 12-HPETE increased as the preincubation time was prolonged. These results suggest that 12-HPETE is a strong inhibitor for the cyclooxygenase pathway.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1985

Abnormal high density lipoprotein of primary biliary cirrhosis analyzed by high performance liquid chromatography.

The lipoprotein profile of patients with primary biliary cirrhosis (PBC) has been assessed by high performance liquid chromatography (HPLC). Without exception, all subjects with PBC had an abnormal high density lipoprotein (HDL), which was larger than normal HDL. The elution time from an HPLC column of the abnormal HDL separated it clearly from normal HDL. The HDL of subjects with asymptomatic and symptomatic PBC could also be distinguished. The HDL of asymptomatic subjects was eluted between that of normal and symptomatic subjects. The lipid and protein composition of abnormal HDL was characterized by an increase in phospholipid and a decrease in protein, resulting in an increase in the ratio of phospholipid/protein. This ratio was higher in symptomatic than in asymptomatic PBC. Incubation of dimyristoyl phosphatidylcholine liposomes with normal serum resulted in the formation of an altered high density lipoprotein. These findings suggest that an overload of phospholipid may play a role in the formation of the abnormal HDL in primary biliary cirrhosis.

Adult↗
PubMed1985

Aspirin inhibition of 1 alpha-hydroxyvitamin D3 or parathyroid hormone induced hypercalcemia in vivo in rats. A mechanism independent of prostaglandin biosynthesis inhibition.

The interactions of calcium-regulating hormones, active forms of vitamin D and parathyroid hormone, and aspirin were studied in rats. Aspirin, a prostaglandin biosynthesis inhibitor, abolished the hypercalcemia induced by 1 alpha-hydroxyvitamin D3 at 20, 50 and 100 mg/kg p.o. in parathyroidectomized or thyroparathyroidectomized rats with or without vitamin D deficiency, and in thyroparathyroidectomized plus nephrectomized rats. Aspirin did not affect the stimulation of intestinal calcium absorption by 1 alpha-hydroxyvitamin D3. By contrast, indomethacin, another prostaglandin biosynthesis inhibitor, did not affect hypercalcemia or stimulation of intestinal calcium absorption by 1 alpha-hydroxyvitamin D3. Aspirin also abolished the hypercalcemic action of parathyroid hormone in rats with or without intact thyroparathyroid glands. Moreover, aspirin alone caused hypocalcemia in rats with intact thyroparathyroid glands. Indomethacin had no effect in either of these systems. These data suggest that aspirin may inhibit bone resorption by the active form of vitamin D or parathyroid hormone via a mechanism independent of prostaglandin biosynthesis inhibition.

Animals↗
PubMed1985

Use of Millipore diffusion chambers to assay in vivo IL-2 activity.

Lymphokine-activated killer (LAK) cells were grown from C57BL/6 mouse spleen cells by culturing the cells with recombinant human IL-2 (r-IL-2). The unlabeled or [3H]uridine-labeled LAK cells were enclosed in a diffusion chamber, which was implanted into the peritoneal cavity of a syngeneic mouse, and the mouse was treated with an i.p. injection of r-IL-2 or saline (control). In order to detect the activity of administered r-IL-2, the diffusion chambers were taken out from the mice 20-40 h after the implantation, and the viability and cytotoxic activity of LAK cells in the chambers were determined by measuring the radioactivity of the cells and their cytotoxicity to EL 4 mouse leukemia cells respectively. When the mice were treated with saline, the radioactivity of LAK cells was greatly decreased. However, when the mice were treated with r-IL-2, the radioactivity of LAK cells was sustained. An i.p. administration of IL-2 also prevented any decrease in the cytotoxic activity of LAK cells.

Animals↗
PubMed1985

Pig-skin epidermal calmodulin: effects of antagonists of calmodulin on DNA synthesis of pig-skin epidermis.

Although epidermal keratinocytes contain significant amounts of calmodulin, the exact role of calmodulin in epidermal biological activity remains to be determined. Pig-skin (epidermal) calmodulin was purified to homogeneity by DEAE/Sepharose- and phenothiazine-affinity-column chromatography. The characteristics of the purified calmodulin proved to be in good agreement with those of calmodulin obtained from other sources. Phenothiazines (trifluoperazine and chlorpromazine), mepacrine, propranolol, and colchicine inhibited the effect of the purified epidermal calmodulin on the calmodulin-deficient phosphodiesterase of bovine heart. These calmodulin antagonists all had inhibitory effects on the thymidine incorporation of pig-skin epidermal keratinocytes. These observations support the assumption that calmodulin might play an important role in epidermal keratinocyte proliferation.

Animals↗
PubMed1985

Lymphokine-activated cell-associated antigen involved in broad-reactive killer cell-mediated cytotoxicity.

Spleen cells from rats which had been hyperimmunized with mouse lymphokine-activated killer (LAK) cells, were fused with the mouse myeloma cell line, P3 X 63 Ag8.653. Antibodies secreted by 1500 cultures were selected by their blocking effect on LAK cell-mediated cytotoxicity in the absence of complement. Two monoclonal antibodies (KBA4 and KBA6) greatly inhibited the cytotoxic activity of LAK cells, which were induced from mouse spleen cells by culture with recombinant human interleukin 2 (r-IL-2). These antibodies also blocked the cytotoxic activity of natural killer (NK) cells, but activated macrophages (A-M phi) were only slightly sensitive to them. However, no effect of the antibodies on the cytotoxic activity of cytotoxic T lymphocytes (CTL) was detected. These data suggest that the specific antigen, lymphokine-activated cell-associated (LAA) antigen, defined by these monoclonal antibodies may be associated with the recognition mechanisms of broad-reactive killer (BRK) cell-mediated cytotoxicity. The observation that low levels of LAA antigen are distributed in all lymphoid cells and that it was significantly enhanced by treatment of the cells with r-IL-2 suggests that the antigen may be involved in lymphocyte-activation mechanisms. We also found that the LAA antigen consists of two distinct polypeptides with Mr of 180,000 and 95,000 Da, which are similar to that of LFA 1 antigen. However, the biological characteristics of LAA antigen did not coincide with those of LFA 1. Therefore, KBA MAb may recognize a carbohydrate epitope distinct from that of LFA 1.

Animals↗
PubMed1985

Partial purification of the apolipoprotein E receptor of rat liver membrane.

The liver has two distinct lipoprotein receptors; one is the apolipoprotein (apo) B, E receptor and the other the apo-E receptor. In this study, the protein to which apo-E HDLc (cholesterol-induced high density lipoprotein containing apo-E as the predominant protein species) bound specifically was partially purified from the rat liver membrane by ion exchange chromatography and preparative gel electrophoresis. The molecular weight of the protein was estimated to be about 36K daltons and the protein bound to 125I-apo-E HDLc in a specific and saturable manner, suggesting that the protein is the apo-E receptor.

Animals↗
PubMed1985

Direct Observation of Reversible and Irreversible Stomatal Responses of Attached Sunflower Leaves to SO(2).

The effects of SO(2) on stomatal aperture of attached sunflower leaves were observed with a remote-control light microscope system that permitted continuous observation of stomatal responses over periods of several hours. The relationship between actual stomatal aperture and stomatal conductance, measured with a porometer, also was examined on leaves before and after exposure to SO(2).A distinction between uninjured and injured regions was clearly visible on leaves after exposure to 1.5 microliters per liter SO(2) for less than an hour. During the exposure, the mean value of apertures for many stomata, which indicates stomatal conductance and transpiration rate, tended to decrease simultaneously in the uninjured and injured regions. However, the rate of decrease in the injured region was slower than that in the uninjured region because of a transient opening induced by water-soaking in the injured region. The transient opening was less common in stomata near veins and veinlets.There was a good correlation between pore width and stomatal conductance measured with a porometer before exposure to SO(2). This correlation continued in leaves exposed to SO(2) until visible, irreversible injury occurred, but then it disappeared.The results of these experiments indicate the necessity of continuous observation of individual stomata under the microscope to understand the effects of air pollutants such as SO(2) on stomatal behavior.

Journal Article↗
PubMed1985

Calmodulin activities are significantly increased in both uninvolved and involved epidermis in psoriasis.

In order to elucidate a part of calmodulin actions in the hyperproliferative state in human epidermis, calmodulin activities in the psoriatic and in the normal human epidermis were determined using calmodulin-deficient phosphodiesterase from bovine heart and purified pig skin epidermal calmodulin as a standard. Skin samples were obtained from 11 normal healthy controls and from both the uninvolved and involved regions of 8 nonconsanguineous psoriatic patients. Pure epidermal samples, prepared by the microdissection method, were used for calmodulin assays. Normal human epidermis contained 270 +/- 13 ng/mg dry weight, whereas calmodulin activities were significantly increased in psoriatic epidermis, 412 +/- 29 ng/mg dry weight for the uninvolved epidermis and 747 +/- 46 ng/mg dry weight for the involved epidermis, respectively. These results suggest that calmodulin may play an important role in cell proliferation in human epidermis.

Adolescent↗
PubMed1985

Changes in collagen types during the healing of rabbit tooth extraction wounds.

Three alpha chains of type V collagen--alpha 1 (V), alpha 2 (V), and alpha 3 (V)--were initially demonstrated together with the expected collagen types I and III in the pepsin-soluble fraction of both normal mandibular bone and tooth extraction wound tissues of rabbits, as analyzed by sodium dodecyl sulfate-gel electrophoresis. The total collagen content of each extraction wound, as determined by the hydroxyproline assay, was observed to increase continuously from day 5 through day 17 and then leveled off or decreased. The ratio of type V to type I collagen was significantly higher in the initial stage of wound healing and decreased sharply down to the level of mandibular bone by day 5. The ratio of type III to type I collagen in the pepsin-soluble fraction increased and reached a maximum on day 5, whereas it was maximal on day 7 in the cyanogen bromide-soluble fraction, and thereafter decreased gradually in both fractions. The ratio for the pepsin-soluble fraction was, however, significantly higher than that for the cyanogen bromide-soluble fraction in the early stage of wound healing.

Alveolar Process↗