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Biomedical subjects

K Minami

Publications and source records attributed to K Minami.

At least 235 records · Page 13Linked to original sources
PubMed1994

Regulation of a non-selective cation channel of cultured porcine coronary artery smooth muscle cells by tyrosine kinase.

A non-selective cation channel was found in primary cultured porcine coronary artery smooth muscle cells. In patch-clamp studies in the cell-attached mode, this channel was activated by bath application of genistein, a specific inhibitor of tyrosine kinase, but not by daidzein, which is similar in structure to genistein but has no inhibitory effect on tyrosine kinase. This channel discriminated poorly between Na+ and K+ (permeability ratio PNa/PK = 1.03), and also transported Ca2+. The single-channel conductance measured with a pipette solution containing 150 mM Na+ was 139 +/- 24 pS (mean +/- SD, n = 5), and that for the inward current measured with 100 mM Ca2+ solution was 25 +/- 9 pS (n = 3). This non-selective cation channel was also activated by staurosporine, a non-specific protein kinase inhibitor, but not by H-7, an inhibitor of protein serine/threonine kinase. These results suggest that the activity of the non-selective cation channel is negatively regulated by tyrosine kinase activity, and thus a decrease of the enzyme activity in porcine coronary artery smooth muscle cells may result in membrane depolarization and Ca2+ entry.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Effects of temperature and sodium on myocardial and hepatocellular fatty acid uptake.

Fatty acid influx into human myocardium was studied in 15 patients during the cooling phase of cardiopulmonary bypass at myocardial temperatures of 37 degrees to 25 degrees C. The fitting of the data to a functional relation, developed in this study, revealed fatty acid influx to be a temperature-dependent saturable process corresponding to a Michaelis-Menten constant (Km) at 37 degrees C of 0.26 +/- 0.084 mumol/g, a maximal fatty acid influx velocity (Vmax) at 37 degrees C of 0.28 +/- 0.045 mumol/g per minute, activation energy for fatty acid binding to the putative carrier (E) of 23.8 +/- 5.6 kcal/mol, and a free energy for conformational change of the carrier (U) of 10.9 +/- 8.0 kcal/mol. In short-term cultured hepatocytes, Km increased in the absence of Na+ from 171 +/- 48 to 301 +/- 71 nmol/L, and Vmax of [3H]oleate decreased from 1063 +/- 69 to 847 +/- 68 pmol/min per milligram protein. The fitting of these data to a functional relation revealed a transmembrane potential-dependent component of parameters E and U to be -0.479 and -0.374 kcal/mol, respectively. It is proposed that for fatty acid influx a protonated fatty acid form is preferred that consists of a Na+ complex with the mesomeric form of nondissociated fatty acid from which Na+ and H+ are released during collision with the carrier.

Animals↗
PubMed1994

[Moisture sorption of gelatin powder and collagen fibers].

Moisture sorption properties of gelatin powder and collagen fibers were investigated on the basis of the moisture sorption isotherm, the differential heat of moisture sorption, the decrease in entropy of moisture sorption and the parameter constants of the applicable isotherm equation. The amount of moisture sorbed on collagen fibers was larger than that on gelatin powder. The water molecules were absorbed on gelatin itself rather than on the active sites of gelatin. They were adsorbed on the polar groups of constitutive amino acids at amounts of moisture sorbed up to one or two monolayers and then were absorbed into collagen fibers at higher monolayers. They were kept loosely in gelatin and tightly in collagen. The structural stability of collagen to moisture was higher than that of gelatin.

Adsorption↗
PubMed1994

Synthesis and structure-activity relationships of 7 beta-[(Z)-2-(2- aminothiazol-4-yl)-3-(substituted)-2-propenoyl-amino]-3- desacetoxymethylcephalosporins.

Synthesis and biological activity of a series of 7 beta-[(Z)-2-(2- aminothiazol-4-yl)-3-(substituted)-2-propenoylamino]-3-cephe m-4-carboxylic acids and their pivaloyloxymethyl esters are described. These acid compounds exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Pivaloyloxymethyl esters of selected compounds in this series were found to be well absorbed from small intestine in mice.

Animals↗
PubMed1994

Synthesis and structure-activity relationships of 7 beta-[(Z)-2-(2- aminothiazol-4-yl)-3-(substituted)-2-propenoylamino]-3-cephems with C-3 substitutions.

Synthesis and biological activity of a series of 7 beta-[(Z)-2-(2- aminothiazol-4-yl)-3-(substituted)-2-propenoylamino]-3-cephe m-4-carboxylic acids with C-3 substitutions and their pivaloyloxymethyl esters are described. These acid compounds exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Pivaloyloxymethyl esters of selected compounds in this series were found to be well absorbed from small intestine in mice. Pivaloyloxymethyl 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-pentenoylamino]-3- carbamoyloxymethyl-3-cephem-4-carboxylase hydrochloride hydrate (S-1108) was finally selected as the candidate for clinical evaluation.

Administration, Oral↗
PubMed1994

Mechanical ventricular support using pulsatile Abiomed BVS 5000 and centrifugal Biomedicus-pump in postcardiotomy shock.

Since we started using ventricular assist devices (VAD) in July 1987 up to August 1993, 63 of 15,650 (0.4%) patients (pts) who underwent open heart surgery were supported postoperatively by VAD at out institution. Forty-three were male and 20 female, mean age 55.5 years. In 49 pts coronary artery bypass grafting (CABG), in 8 pts valve surgery, in 3 pts combined CABG and valve surgery and in 3 pts corrective procedures for congenital heart disease were performed. Perioperative myocardial infarction was the most frequent indication (73%). In 37 of the 63 pts (58.7%) a centrifugal (Biomedicus pump (group A) was used and in 26 pts (41.3%) a pulsatile Abiomed BVS 5000 (group B). Fourteen of 37 pts (38%) in group A were weaned from the VAD and all of them were discharged. Twenty-three pts were unable to be weaned and 19 of these pts died. The remaining 4 pts were transplanted successfully and subsequently 3 died and 1 was discharged. In all, 15 pts (39%) were long-term survivors. Sixteen of 26 pts (62%) in group B were weaned from VAD and 13 (50%) of them were discharged of whom 3 died. Ten patients were unable to be weaned and 7 of these died. The remaining 3 pts were transplanted successfully. In all, 16 pts (61.5%) were long-term survivors. The shorter the interval between beginning resuscitation and application of VAD the better the outcome. Younger age, VAD installation in OR, support time between 2 and 7 days and Abiomed pump, influence the survival rate positively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

C-type natriuretic peptide stimulates catecholamine synthesis through the accumulation of cyclic GMP in cultured bovine adrenal medullary cells.

We examined the effects of C-type natriuretic peptide (CNP) on cyclic GMP production and catecholamine synthesis in cultured bovine adrenal medullary cells. 1) CNP increased intracellular cyclic GMP content in a concentration-dependent manner (10-1000 nM). 2) The cyclic GMP production induced by 1 microM CNP reached a 200-fold increase, and the effect of CNP was most potent among the natriuretic peptide family. 3) The CNP-induced cyclic GMP production was attenuated by endothelin (1 microM) and angiotensin II (0.1-1 microM). 4) When the cells were cultured with hypertonic NaCl medium, the CNP-induced cyclic GMP production was potentiated in a time (1-4 days)- and concentration (25-100 mM)-dependent manner. 5) CNP stimulated the synthesis of 14C-labeled catecholamines from [14C] tyrosine but not from [14C] dopa. The stimulatory effect of CNP on the 14C-labeled catecholamine synthesis was observed at the concentrations of 100 to 100 nM. 6) 8-Bromo cyclic GMP, a membrane-permeable cyclic GMP analog, and sodium nitroprusside, an activator of soluble guanylate cyclase, also stimulated the synthesis of 14C-labeled catecholamines from [14C]tyrosine, whereas C-ANF, a specific ligand for the ANP-C (clearance) receptor that does not increase cyclic GMP content, failed to stimulate the synthesis of 14C-labeled catecholamines. 7) CNP (1 microM) as well as 8-bromo cyclic GMP and sodium nitroprusside increased the activity of tyrosine hydroxylase in the cells. These results suggest that in the adrenal medulla, CNP is a potent agonist for cyclic GMP production, which is modulated by endothelin, angiotensin II and the hypertonic NaCl condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMed1993

Receptors for C-type natriuretic peptide in cultured rat glial cells.

To characterize sites of action of C-type natriuretic peptide (CNP) in the glial cells, the effect of CNP on cGMP accumulation and the binding of [125I]CNP in rat astrocyte RCR-1 cells were studied. CNP stimulated cGMP accumulation in the cells from 10(-9) M in a dose-dependent manner, but ANP (atrial natriuretic peptide) had a negligible effect on cGMP accumulation in the cells. [125I]CNP was bound to the cells and its Kd value was 2 orders of magnitude lower than that of the ED50 value for stimulation of cGMP accumulation in the cells. Not only CNP but also ANP displaced [125I]CNP binding to the cells. These results suggest that RCR-1 cells have a B-receptor which contains a guanylate cyclase domain and is preferentially activated by CNP, and that they also have a C-receptor which does not contain a guanylate cyclase domain that reacts with both ANP and CNP.

Animals↗
PubMed1993

Protein kinase C inhibits the Ca(2+)-activated K+ channel of cultured porcine coronary artery smooth muscle cells.

The effect of protein kinase C (C-kinase) on the Ca(2+)-activated K+ channel (KCa-channel) was studied in cultured smooth muscle cells from porcine coronary artery by the patch-clamp technique. In cell-attached patches, bath application of phorbol 12-myristate 13-acetate (PMA, 1 microM), a C-kinase activator, significantly decreased the open probability of the activated KCa-channel in the presence of the calcium ionophore A23187 (20 microM), which increases intracellular Ca2+. This decrease in the open probability was reversed by subsequent application of staurosporine (1 nM), a C-kinase inhibitor. Application of 1-oleoyl-2-acetylglycerol (OAG, 30 microM) or 1,2-dioctanoylglycerol (DG8; 30 microM), activators of C-kinase, also inhibited KCa-channel activation by A23187, and these inhibitions were also reversed by staurosporine. PMA (1 microM) also inhibited KCa-channel activation by dibutylyl cyclic AMP (db-cAMP, 2 mM) or caffeine (30 mM). In inside-out patches, bath application of the C-kinase fraction from rat brain in the presence of ATP (1 mM) and PMA (1 microM) markedly inhibited the KCa-channel. These results indicate that activation of C-kinase inhibits the KCa-channel and may cause membrane depolarization and vascular contraction.

Adenosine Triphosphate↗
PubMed1993

Dynamics of iron-ascorbate-induced lipid peroxidation in charged and uncharged phospholipid vesicles.

Peroxidation of egg yolk phosphatidylcholine (egg PC) liposomes was induced by addition of ascorbic acid (AsA) and Fe(II) in the presence of a trace of autoxidized egg PC (PC-OOH), but not in the absence of PC-OOH. PC-OOH was degraded upon addition of AsA and Fe(II) but not of either one alone. The results suggest that PC-OOH is necessary to initiate lipid peroxidation by AsA/Fe(II). AsA oxidation in the bulk water phase was also associated with an increase in lipid peroxidation by AsA/Fe(II) in the presence of PC-OOH, but not in the absence of PC-OOH. Furthermore, the spin probe 12-NS [12-(N-oxyl-4,4'-dimethyloxazolidin-2-yl)stearic acid], which labels the hydrophobic region of dimyristoyl phosphatidylcholine (DMPC) liposomal membranes, was degraded upon addition of AsA and Fe(II) in the presence of PC-OOH, but not in the absence of PC-OOH. These results indicate that the "induction message" that is associated with decreases of PC-OOH and AsA in the initiation step of lipid peroxidation must be transferred from the membrane surface to the inner hydrophobic membrane region. AsA in the bulk phase was oxidized faster and more extensively upon its addition together with Fe(II) to egg PC liposomes than to DMPC liposomes, though the initial content of PC-OOH in the former was 5-10 times lower than in the latter. This suggests that, in egg PC liposomes, the OOH-groups of new PC-OOH generated in the inner membrane regions must become accessible from the surface, enabling reaction with AsA/Fe(II) which in turn would result in an extensive decrease in AsA.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascorbic Acid↗
PubMed1993

Traumatic sinus of Valsalva fistula and aortic valve rupture.

A rare case of nonpenetrating trauma-induced fistula from the right sinus of Valsalva to the right atrium and aortic cusp disruption is reported. The trauma occurred 2 1/2 years previously. The fistula was closed with a Dacron patch, and the cusp tear was sutured.

Accidents, Traffic↗
PubMed1993

Mechanism of activation of the Ca(2+)-activated K+ channel by cyclic AMP in cultured porcine coronary artery smooth muscle cells.

Activation of the Ca(2+)-activated K+ channel (KCa-channel) by adenosine 3', 5'-cyclic monophosphate (cAMP) and cAMP-dependent protein kinase (A-kinase) in cultured smooth muscle cells from porcine coronary artery was investigated using the patch-clamp technique. In cell-attached patches, the KCa-channel was activated when forskolin (10 microM) was applied to the bath. In excised inside-out patches, application of 50 microM cAMP to the bath activated the KCa-channel in the presence of A-kinase (10 units/ml) and ATP (1 mM). In addition, the KCa-channel was activated directly by application of cAMP to the cytoplasmic side of the membrane in the absence of A-kinase. The activation by cAMP or by A-kinase required intracellular Ca2+, and was enhanced by increase of intracellular Ca2+. At a low concentration (3 x 10(-7) M) of Ca2+, more than 2 mM cAMP was required for activation of the KCa-channel, but with 10(-6) M Ca2+, 100 microM cAMP was sufficient for activation. These results suggest that there are two mechanisms of activation of the KCa-channel by cAMP: direct activation, and indirect activation via phosphorylation of the channel by A-kinase.

Animals↗
PubMed1993

Delayed brachial plexus paralysis due to subclavian pseudoaneurysm after clavicular fracture.

Injuries to the brachial plexus and subclavian artery are serious complications of shoulder girdle trauma. Due to the close anatomical relationship between the brachial plexus and the subclavian artery in the thoracic outlet, both structures are often simultaneously involved in shoulder girdle injuries. Isolated lesions of the subclavian artery or the brachial plexus can also occur, especially with clavicular fractures. When a false subclavian aneurysm leads to a gradually increasing compression of the brachial plexus, the neurological signs and symptoms develop insidiously after the traumatic event.

Adult↗