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Biomedical subjects

K Minakuchi

Publications and source records attributed to K Minakuchi.

At least 19 recordsLinked to original sources
PubMed2006

FKBP12 functions as an adaptor of the Smad7-Smurf1 complex on activin type I receptor.

The cytoplasmic immunophilin FKBP12, a 12 kDa FK506-binding protein, has been shown to act as an inhibitor for transforming growth factor-beta (TGF-beta) signaling. FKBP12 binds to the glycine- and serine-rich motif (GS motif) of the TGF-beta type I receptor, and functions as a secure switch to prevent the leaky signal. Upon stimulation with ligand, FKBP12 is released from the receptor to fully propagate the signal. We found that activin, a member of TGF-beta superfamily, also induced the dissociation of FKBP12 from the activin type I receptor (ALK4). However, we observed that the released FKBP12 associates again with the receptor a few hours later. FKBP12 also interacted with another inhibitory molecule of activin signal, Smad7, in an activin-dependent manner, and formed a complex with Smad7 on the type I receptor. FK506, a chemical ligand for FKBP12, which dissociates FKBP12 from the receptor, decreased the interaction between Smad7 and Smad ubiquitin regulatory factor 1 (Smurf1). FK506 also inhibited the ubiquitination of the type I receptor by Smurf1. These findings indicate a new inhibitory function of FKBP12 as an adaptor molecule for the Smad7-Smurf1 complex to regulate the duration of the activin signal.

Activin Receptors, Type I↗
PubMed2001

Effects of losartan in combination with or without exercise on insulin resistance in Otsuka Long-Evans Tokushima Fatty rats.

Hypertension often complicates type 2 diabetes mellitus, and angiotensin converting enzyme inhibitor treatment has been shown to improve insulin resistance in such cases. However, the effect of angiotensin II type-1 (AT(1)) receptor antagonists on insulin resistance is still controversial. To gain further information on this effect, we examined the effect of losartan on insulin resistance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus. Losartan administration alone lowered systolic blood pressure, but did not improve oral glucose tolerance test or insulin resistance in OLETF rats. However, the administration of losartan with exercise significantly improved both systolic blood pressure and insulin resistance relative to control OLETF rats. On the other hand, losartan treatment, regardless of exercise, increased glucose uptake in excised soleus muscle and fat cells. To explore the beneficial effect of losartan on skeletal muscle glucose uptake, we examined intracellular signaling of soleus muscle. Although Akt activity and glucose transporter type 4 (GLUT4) expressions were not affected by losartan with or without exercise, extracellular signal-regulated kinase (ERK1/2) and p38 mitogen-activated protein (MAP) kinase activities were increased by both interventions. These results indicate that angiotensin AT(1) receptor antagonist improved local insulin resistance, but not systemic insulin resistance. These findings may explain the controversy over the effect of angiotensin AT(1) receptor antagonists on insulin resistance in clinical use. The enhancing effect of angiotensin AT(1) receptor antagonist on skeletal muscle glucose uptake may be attributable to MAP kinase activation or other mechanisms rather than phosphatidylinositol 3-kinase activation.

Adipocytes↗
PubMed2001

Endothelium-dependent relaxation by cilostazol, a phosphodiesteras III inhibitor, on rat thoracic aorta.

The relaxation effect of cilostazol, a phosphodiesterase III inhibitor, on the thoracic aorta was investigated. Cilostazol induced the relaxation of the thoracic aorta precontracted by phenylephrine in a concentration-dependent manner. The concentration-dependent relaxation was shifted to the right in the endothelium denuded aorta compared with that of intact endothelium, suggesting that this relaxation was partly dependent on endothelium. Cilostazol-induced relaxation of thoracic aorta tone was reversed by treatment with N(G)-nitro L-arginine (L-NNA), a competitive inhibitor of nitric oxide (NO) synthase. Cilostazol also significantly increased the NO level in the porcine thoracic aorta. In rats treated with cilostazol, the urinary excretion of nitrites, a stable metabolite of NO, and basal production of NO of the aortic ring were significantly greater than in those without treatment. These findings indicate that cilostazol-induced vasodilation of the rat thoracic aorta was dependent on the endothelium, which released NO from aortic endothelial cells.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2001

Role of stem cell factor and c-kit signaling in regulation of fetal intestinal epithelial cell adhesion to fibronectin.

The interaction of stem cell factor (SCF) and c-kit is considered to be an important signaling event for the homeostasis of the epithelial barrier function in the intestinal tract. This study was designed to investigate the role of the SCF and c-kit signaling pathway in adhesion of intestinal epithelial cells (IECs) to fibronectin (FN) using primary cells. Fetal murine IECs were prepared from the small intestine of mouse fetus. The mRNAs coding for SCF in mesenchymes and c-kit in IECs were detected by reverse transcription-PCR. The expression of FN receptor VLA-5 on IECs was examined by flow cytometry. A cell adhesion assay showed that the stimulation of IECs with SCF increased the number of cells adhering to FN. Experiments using specific antibody against SCF indicated that this increase in cell adhesion was SCF-dependent. On the other hand, SCF did not influence the expression of VLA-5 on IECs. The IEC adhesion to FN was inhibited by specific antibody against the FN receptor (VLA-5), as well as competitive Arg-Gly-Asp (RGD) peptide. When alteration of intracellular signal transduction induced by SCF was examined, it was found that SCF stimulated a tyrosine-specific c-kit autophosphorylation cascade of IECs. Further, preincubation of IECs with an optimal concentration of genistein resulted in the inhibition of SCF-induced c-kit phosphorylation and adhesion of IECs to FN. These results suggested that adhesion of immature IECs to FN is regulated by activation of RGD-dependent VLA-5 through the SCF and c-kit signal transduction pathway. SCF, which may be produced by mesenchymes locally, is an important regulatory factor for the adhesion of immature IECs to basement membrane matrix via VLA-5 and FN interaction. This cytokine-regulated interaction between VLA-5 and FN may play an important role in the development and wound repair of the intestinal tract.

Animals↗
PubMed2001

The effect of tranexamic acid on cochlear blood flow in guinea pigs measured by laser Doppler flowmetry.

OBJECTIVE: This study investigated the vasoactive effect of tranexamic acid on the cochlear blood flow in guinea pigs. METHOD: 3 ml solution (infusion speed, 0.5 ml/min) containing different concentrations of tranexamic acid was intravenously infused into 15 guinea pigs under general anesthesia. The guinea pigs were grouped according to four levels of dosage of the medicine (470 mg/kg, n=6; 220 mg/kg, n=3; 4 mg/kg, n=3; 1 mg/kg, n=3). Before administering medicine, saline solution was administered in similar volume and speed as a control. The cochleas were surgically exposed and laser Doppler flowmetry monitored cochlear blood flow volume (CBF). The left femoral artery was cannulated to permit a transducer to monitor systemic blood pressure (BP). RESULTS: (1) Stimulatory effect of tranexamic acid on CBF was dose-dependent at concentrations of 1-470 mg/kg and, (2) the time course of changes in CBF was almost identical to that in BP following tranexamic acid administration. CONCLUSION: Preliminary findings suggest that intravenous administration of tranexamic acid increases CBF due to vasomotorial mechanism effect on BP.

Animals↗
PubMed2001

[A case of disseminated intravascular coagulopathy (DIC) and multiple organ failure (MOF) after ingestion of hydrochloric acid].

Ingestion of caustic materials causes systemic damages and requires treatment in an intensive care unit. This report presents a case of disseminated intravascular coagulopathy (DIC) and multiple organ failure after ingestion of hydrochloric acid in an attempted suicide. The patient was admitted to the emergency ward within 1 hr after ingestion of 60 ml of 35% hydrochloric acid. Initial blood examination suggested hemolysis without anemia or thrombocytopenia. Arterial blood gas analysis exhibited evident metabolic acidosis with hypoxia. Two hours after ingestion, severe hemolysis, anemia, thrombocytopenia emerged with abnormal results from clotting and fiblinolysis tests, and a diagnosis of DIC was made. Subsequently, conjugate deviation and severe bleeding diathesis appeared. No evidence for gastrointestinal bleeding and brain hemorrhage was obtained in our abdominal echography and brain computed tomography, respectively. In spite of vigorous suppurative therapy including transfusion of blood, fresh frozen plasma, and catecholamines, the patient expired 29 hrs after ingestion. Autopsy was not carried out. Rapid progressive DIC as an acute complication of acid ingestion must be born in mind.

Acidosis↗
PubMed2000

Case of hemorrhagic shock due to hypermenorrhea during anticoagulant therapy.

We report the case of a patient with uterine myoma who developed uncontrollable massive hemorrhage from the uterus during anticoagulant therapy after cardiac valve replacement and required hysterectomy. There was a discrepancy between the laboratory findings regarding the blood coagulation system and the clinical manifestations, suggesting a combination of multiple factors, such as a hormonal imbalance. This was a case that demanded strict attention to the management of the uterine lesions during the conduct of anticoagulant treatment.

Anticoagulants↗
PubMed2000

Long-term regulation of catecholamine formation by ouabain in cultured bovine adrenal chromaffin cells.

The long-term effects of ouabain, an inhibitor of Na+/K+ -ATPase, on catecholamine formation in cultured bovine adrenal chromaffin cells were examined. The increase in [14C]catecholamine formation from [14C]tyrosine induced by ouabain was dependent on incubation time, and its maximal effect was observed after incubation for 8 h. The stimulatory effect of ouabain was concentration dependent (10-300 nM), causing maximal stimulation at 300 nM. The formation of [14C]catecholamines induced by ouabain was not increased by incubation with [14C]DOPA instead of [14C]tyrosine. Ouabain-induced [14C]catecholamine formation was influenced by decreases in extracellular Ca2+ concentration, but not by the presence of cycloheximide or actinomycin D. These results suggested that ouabain stimulates continuous activation of hydroxylation of tyrosine through a Ca2+ -dependent mechanism in cultured bovine adrenal chromaffin cells.

Animals↗
PubMed2000

Synergistic effect of combining theophylline and drugs that potentially elevate serum creatine kinase.

An increase in the serum creatine kinase (CK) level is one of the side effects of theophylline; on rare occasions, the increase may be followed by rhabdomyolysis. Theophylline is often administered with drugs that potentially elevate the serum CK level (CK-elevating drugs) such as beta-agonists and steroids. However, the effects of the combined treatment of theophylline and CK-elevating drugs have not been reported. We, therefore, retrospectively investigated the effects of combined treatment on the serum CK level, in 391 asthmatic outpatients. In this study, the number and type of the CK-elevating drugs administered, and the serum levels of CK and theophylline, were investigated. The patients were divided into four groups: the theophylline-treated and CK-elevating drug-treated group, the theophylline-treated and non-CK-elevating drug-treated group, the non-theophylline-treated and CK-elevating drug-treated group, and the non-theophylline-treated and non-CK-elevating drug-treated group. The theophylline-treated and CK-elevating drug-treated group showed about 100% higher serum CK levels (225 IU/L) than any other group (102-124 IU/L), and no increase in the serum theophylline level. This result indicates that there is a synergistic effect of theophylline and CK-elevating drugs on the serum CK level. The combined treatment of theophylline and CK-elevating drugs induces a synergistic increase in the serum CK level, indicating not pharmacokinetic but pharmacodynamic interactions with these drugs.

Adolescent↗
PubMed1999

Stimulatory effect of enkephalins on calcium efflux from bovine adrenal chromaffin cells in culture.

The effects of leucine- and methionine-enkephalin, opiate peptides, on Ca2+ efflux from cultured bovine adrenal chromaffin cells were examined. These enkephalins stimulated the efflux of 45Ca2+ from cells in a concentration-dependent manner (10(-8) M-10(-6) M). Leucine-enkephalin did not increase the intracellular free Ca2+ level, 45Ca2+ uptake, catecholamine secretion, cAMP level or cGMP level. The peptide-stimulated 45Ca2+ efflux was not inhibited by incubation in Ca2+-free medium, but was inhibited by incubation in Na+-free medium. These results indicate that enkephalins stimulate extracellular Na+-dependent 45Ca2+ efflux from cultured bovine adrenal chromaffin cells, probably by stimulating membrane Na+/Ca2+ exchange.

Adrenal Medulla↗
PubMed1999

Nitric oxide-forming reactions of the water-soluble nitric oxide spin-trapping agent, MGD.

The objective of this study was to elucidate the nitric oxide-forming reactions of the iron-N-methyl-D-glucamine dithiocarbamate (Fe-MGD) complex from the nitrogen-containing compound hydroxyurea. The Fe2+(MGD)2 complex is commonly used in electron paramagnetic resonance (EPR) spectroscopic detection of NO both in vivo and in vitro. The reaction of Fe2+(MGD)2 with NO yields the resultant NO-Fe2+(DETC)2 complex, which has a characteristic triplet EPR signal. It is widely believed that only NO reacts with Fe2+(MGD)2 to form the NO-Fe2+(MGD)2 complex. In this report, the mechanism leading to the formation of NO-Fe2+(MGD)2 was investigated using oxygen-uptake studies in conjunction with the EPR spin-trapping technique. We found that the air oxidation of Fe2+(MGD)2 complex results in the formation of the Fe3+(MGD)3 complex, presumably concomitantly with superoxide (O3*-). Dismutation of superoxide forms hydrogen peroxide, which can subsequently reduce Fe3+(MGD)3 back to Fe2+(MGD)2. The addition of NO to the Fe3+(MGD)3 complex resulted in the formation of the NO-Fe2+(MGD)2 complex. Hydroxyurea is not considered to be a spontaneous NO donor, but has to be oxidized in order to form NO. We present data showing that in the presence of oxygen, Fe2+(MGD)2 can oxidize hydroxyurea to yield the stable NO-Fe2+(MGD)2 complex. These results imply that hydroxyurea can be oxidized by reactive oxygen species that are formed from the air oxidation of the Fe2+(MGD)2 complex. Formation of the NO-Fe2+(MGD)2 complex in this case could erroneously be interpreted as spontaneous formation of NO from hydroxyurea. The chemistry of the Fe2+(MGD)2 complexes in aerobic conditions must be taken into account in order to avoid erroneous conclusions. In addition, the use of these complexes may contribute to the overall oxidative stress of the system under investigation.

Chelating Agents↗
PubMed1999

Plasma levels of free and sulfoconjugated catecholamines in patients with atherosclerosis.

We have studied the relationship between free and sulfoconjugated catecholamines (CAs) in the plasma of patients with various cardiovascular diseases and have described the physiological significance of sulfoconjugated CAs in plasma. In the present study, we measured free and sulfoconjugated dopamine (DA) and noradrenaline (NA) in the plasma of patients with atherosclerosis (AS). Results showed that the plasma levels of free DA and NA in patients with atherosclerosis were higher than those in control subjects. Moreover, it was also observed that the plasma levels of conjugated DA and NA in patients had a tendency to be higher than the levels in control subjects. These results suggest the involvement of free CAs in atherosclerosis and that elevated free CAs may be converted to sulfoconjugated forms in patients with atherosclerosis.

Adult↗
PubMed1999

[Evaluation of dissolution behavior for the products containing tegafur and uracil].

Generic drugs are widely used with the object of cost saving in many Japanese therapeutic scenes now. The products containing the same active ingredient(s), even if they are innovative drugs or generic ones, must be designed to possess the equivalent quality. In this report, we observed the dissolution behavior patterns of three generic drugs that contain Tegafur and Uracil, drugs A, B, and C, and compared them with that of an innovative product, UFT. Drugs B and C were similar to UFT in the dissolution rate of Tegafur, but drug A was not. On the dissolution rate of Uracil, all the generic products, drugs A, B and C, did not amount to the level equivalent to that of UFT. Therefore, these generic products did not indicate the same dissolution behavior pattern as UFT. It was suggested that the pharmaceutical technology used in the manufacture was not equivalent even if the products of the same dosage form contain the same kind and content of the active ingredient(s).

Capsules↗
PubMed1999

Possible role of bradykinin on stimulus-secretion coupling in adrenal chromaffin cells.

Nonapeptide bradykinin is known to be a central nervous system neurotransmitter and to play a role in regulation of neuronal function. However, few details are known of the function of its peptide on stimulus-secretion coupling in neuronal cells. In this article, the role of bradykinin on catecholamine biosynthesis, secretion and Ca2+ movement in adrenal chromaffin cells as a model for catecholamine-containing neurons are examined. Bradykinin receptors are classified as B1 and B2 receptor subtypes. These receptors are present on the adrenal chromaffin cell membrane. Bradykinin increases the influx of Ca2+ and the turnover of phosphoinositide through the stimulation of bradykinin B2 receptor. The secretion of catecholamine from the cells is initiated by the raise of [Ca2+]i. An increase in [Ca2+]i and production of diacylglycerol stimulate the activation of calcium-dependent protein kinases. These kinases stimulate the activation of tyrosine hydroxylase, a rate-limiting enzyme in the biosynthesis of catecholamine. Otherwise, bradykinin increases Ca2+ efflux from the cells through the stimulation of the bradykinin-B2 receptor. This action may be explained by an extracellular Na(+)-dependent mechanism, probably through acceleration of Na+/Ca2+ exchange. It is interesting that bradykinin, which stimulates the biosynthesis and secretion of catecholamine in adrenal chromaffin cells, plays a role in the termination of calcium-signal transduction through the stimulation of Ca2+ efflux from the cells.

Adrenal Glands↗
PubMed1999

[Bacteriological and clinical break points: evaluation of the usefulness of cefozopran based on MIC].

Drug sensitivity of clinically isolated bacteria to cefozopran (CZOP), which is a new cephem antibiotic, was investigated, and the usefulness of the drug was evaluated from the viewpoint of bacteriological and clinical (pneumonia) break points. The following results were obtained. 1. According to bacteriological break points, methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus spp. showed low sensitivity to cefozopran (CZOP). However, the sensitivity of methicillin-sensitive Staphylococcus aureus (MSSA), E. coli, and Klebsiella spp., which are often isolated as pathogens of common infections, was 100%, that of Enterobacter spp., Serratia sp., and Citrobacter sp. was 90% or higher, and that of Pseudomonas aeruginosa was 80% or higher; the values were comparable to or better than those for ceftazidime (CAZ). These results suggest a expanded antibacterial spectrum and enhanced antibacterial potency of CZOP. 2. The estimated response rate of pneumonia to CZOP was 87.5% in outpatients and 51.9% in inpatients. Therefore, CZOP is considered to be one of the first choices especially in outpatient empiric therapy.

Cephalosporins↗
PubMed1998

Effects of a time-varying strong magnetic field on transient increase in cytosolic free Ca2+ induced by bradykinin in cultured bovine adrenal chromaffin cells.

We tested the effects of exposure to a time-varying magnetic field changing between 0.07 and 1.7 T at an interval of 3 s on transient increase in intracellular Ca2+ stimulated by bradykinin in bovine adrenal chromaffin cells. Addition of bradykinin induced the increase in intracellular Ca2+ within a few minutes. The exposure to the magnetic field perfectly suppressed the increase in intracellular Ca2+ in Ca2+-free medium. The inhibition occurred for 15 min when the maximum magnetic flux density was more than 1.4 T. These results suggest that the exposure inhibits Ca2+ release from intracellular Ca2+ stores.

Animals↗
PubMed1998

Correlation between the growth of uterine leiomyomata and estrogen and progesterone receptor content in needle biopsy specimens.

OBJECTIVE: To examine the relationship between estrogen receptor (ER) and progesterone receptor (PR) content in needle biopsy specimens and the growth of uterine leiomyomata after biopsy. DESIGN: Prospective clinical study. SETTING: University teaching hospital. PATIENT(S): Thirty-one women with uterine leiomyomata and a normal menstrual cycle. INTERVENTION(S): Transcervical needle biopsy of uterine leiomyomata. MAIN OUTCOME MEASURE(S): The relationships between histologic features (smooth muscle content, immunohistochemical expression of ER and PR) and the percent increase over a 12-month observation period in the volume of the largest myoma nodule measured by magnetic resonance imaging were analyzed. RESULT(S): Both the density and intensity of immunohistochemical staining of PRs in uterine leiomyoma tissue showed significant positive correlation with leiomyoma growth. CONCLUSION(S): The growth of uterine leiomyomata can be determined by histologic and immunohistochemical analysis of needle biopsy specimens from uterine leiomyomata.

Adult↗