Biomedical subjects

M Kansha

Publications and source records attributed to M Kansha.

4 recordsLinked to original sources

PubMed2001

Propofol inhibits FMLP-stimulated phosphorylation of p42 mitogen-activated protein kinase and chemotaxis in human neutrophils.

Propofol is used in the peri-operative setting and may affect some neutrophil functions. The effects of propofol on the function and intracellular signal transduction systems of neutrophils is controversial. Mitogen-activated protein kinase families (MAPKs) are members of the intracellular signal-transducing systems in eukaryotes. MAPKs have been shown to be involved in neutrophil chemotaxis by the use of PD98059, the specific inhibitor of MAPK/ERK kinase (MEK). The effects of propofol in dimethyl sulfoxide on phosphorylation of MAPKs and chemotaxis were investigated in human neutrophils. Isolated neutrophils (2 x 10(7) cells per ml) from healthy volunteers were incubated with propofol (2-500 microM) and stimulated by N-formyl-L-methionyl-phenylalanine (FMLP) (100 nM). The effects of propofol on the phosphorylation of p44/42 MAPK were investigated by immunoblotting. The effects of FMLP (1 microM) on chemotaxis were investigated with the under-agarose method. The phosphorylation of p42 MAPK and chemotaxis stimulated by FMLP were both inhibited by propofol at clinically relevant concentrations (> or = 10 and > or = 20 microM respectively). PD98059 (50 microM) also inhibited chemotaxis stimulated by FMLP, suggesting the involvement of p42 MAPK in the response. Propofol might therefore inhibit human neutrophil chemotaxis, at least in part, by suppressing the p44/42 MAPK pathway.

Anesthetics, Intravenous↗

PubMed1999

Dibucaine and tetracaine inhibit the activation of mitogen-activated protein kinase mediated by L-type calcium channels in PC12 cells.

BACKGROUND: An elevation of the intracellular calcium level, which is mediated by N-methyl-D-aspartate receptors and L-type Ca2+ channels both, activates the mitogen-activated protein (MAP) kinase signaling pathway involved in synaptic modification. It has recently been suggested that MAP kinase plays a role in coupling the synaptic excitation to gene expression in the nucleus of postsynaptic neurons. Because the effects of local anesthetics on cellular signal transduction in neuronal cells are not well-known, the authors investigated whether they affect the MAP kinase signaling pathway using PC12 cells. METHODS: The cells were stimulated with either 50 mM KCl or 1 microM ionomycin, and activated MAP kinase was thus immunoprecipitated. The immunocomplexes were then subjected to an Elk1 phosphorylation assay. Both the phosphorylation of MAP kinase and the induction of c-Fos were detected by immunoblotting. RESULTS: Pretreatment of the cells with 1 mM (ethylenedioxy)-diethyl-enedinitrilotetraacetic acid or 5 micron nifedipine blocked the MAP kinase activation induced by 50 mM KCl, whereas pretreatment with 2 microM omega-conotoxin GIVA did not. The expression of c-Fos induced by potassium chloride was also suppressed by dibucaine, tetracaine (concentrations that inhibited 50% of the activity of positive control [IC50s] were 16.2+/-0.2 and 73.2+/-0.7 microM, respectively), and PD 98059, a mitogen-activated/extracellular receptor-regulated kinase inhibitor. Higher concentrations of dibucaine and tetracaine were needed to suppress the activation of MAP kinase induced by ionomycin (the IC50 values of dibucaine and tetracaine were 62.5+/-2.2 and 330.5+/-32.8 microM, respectively) compared with potassium chloride (the IC50 values of dibucaine and tetracaine were 17.7+/-1.0 and 70.2+/-1.2 microM, respectively). Although probable targets of these local anesthetics might be L-type Ca2+ channels or components between Ca2+ and Ras in MAP kinase pathway, the possibility that they directly affect MAP kinase still remains. CONCLUSIONS: Dibucaine and tetracaine at clinical concentrations were found to inhibit the activation of MAP kinase and the expression of c-Fos mediated by L-type Ca2+ channels in PC12 cells. The suppression of MAP kinase pathway may thus be a potential target site for the actions of dibucaine and tetracaine, including the modification of the synaptic functions.

Anesthetics, Local↗

PubMed1997

Anesthetic management of children with moyamoya disease.

A review of the surgical and postoperative records of 127 revascularization procedures performed on 82 children with Moyamoya disease was done to evaluate changes we made in anesthetic management in response to perioperative complications. From 1982 to 1996, out of 82 children who underwent revascularization surgery at our hospital, five developed perioperative complications. One developed circulatory instability during surgery; the cause seemed to be a depth of anesthesia insufficient for preventing surgical stress. To rectify this problem, an increased dose of fentanyl was used to improve the maintenance of anesthesia. Four patients developed cerebral infarction during the early postoperative period due, in part, to inadequate management of postoperative pain. We began to administer supplemental doses of meperidine to patients after they emerged from anesthesia to provide better control of postoperative pain. Our review confirmed the effectiveness of these measures. The data suggest that during the perioperative management of children with Moyamoya disease, close attention should be paid to balancing the patients' anesthetic state against surgical stress and providing adequate postoperative analgesia.

Analgesics, Opioid↗

PubMed1993

Decrease in the phosphotyrosine phosphatase activity in the plasma membrane of human neutrophils on stimulation by phorbol 12-myristate 13-acetate.

Phorbol 12-myristate 13-acetate (PMA) induced a decrease in the phosphotyrosine phosphatase (PTPase) activity in human neurophils. The decrease in the activity induced by PMA was blocked by the treatment of the cells with staurosporine, indicating that protein kinase C is involved in the decrease. The PTPase activity was localized in the plasma membrane. The activity in the membrane with the optimum pH at 5.5 had a Km value for phosphotyrosine of 2.2 mM and Vmax of 2.0 mumol/min per mg of protein. No activity was observed against phosphoserine and phosphothreonine. Vanadate, molybdate, zinc and a sulfhydryl reagent, p-chloromercuribenzenesulphonic acid, inhibited the PTPase. The PMA-induced decrease in activity was almost completely recovered by treatment of the plasma membrane with Triton X-100 at low concentrations which did not solubilize the activity from the membrane. When the plasma membrane was treated with trypsin, the PTPase of the membrane from PMA-treated cells was mostly protected from the proteinase attack while that from the resting cells was not protected. Pretreatment of the plasma membrane with Triton X-100 enabled trypsin to gain access to all the PTPase in the membrane from both PMA-treated and resting cells. The PMA treatment affected neither subcellular localization of the PTPase nor the orientation of the plasma membrane vesicles. These findings suggest that conformational changes of the enzyme induced by PMA result in the decrease in PTPase activity.

Alkaloids↗