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Biomedical subjects

Y Fukushi

Publications and source records attributed to Y Fukushi.

At least 19 recordsLinked to original sources
PubMed1999

Heterologous desensitization of muscarinic receptors by P2Z purinoceptors in rat parotid acinar cells.

We studied the heterologous desensitization of muscarinic receptors by ATP in fura-2-loaded rat parotid acinar cells. Exposure to ATP or 3'-o-(4-benzoyl) benzoyl-ATP shortened the duration and decreased the magnitude of acetylcholine-induced Ca2+ release from intracellular Ca2+ stores in a dose-dependent manner. The shortening was observed only in an early stage of desensitization (within 20 s), whereas the decrease in the magnitude of the response was dependent upon the time the cells were exposed to the nucleotides. Atropine induced a profound shortening during the progressive decrease in the magnitude of acetylcholine-induced Ca2+ release. 3'-o-(4-Benzoyl) benzoyl-ATP did not induce an increase in the cytosolic Ca2+ concentration when the cells were incubated in the Ca2+- and Na+-free medium, but it did induce a strong desensitization of muscarinic receptors. The specific protein kinase C inhibitor bisindoylmaleimide resensitized the 3'-o-(4-benzoyl) benzoyl-ATP-treated muscarinic receptors. Phorbol 12-myristate 13-acetate potentiated the desensitization of muscarinic receptors. Ceramides that prevent the activation of phospholipase D resensitized the 3'-o-(4-benzoyl) benzoyl-ATP-treated muscarinic receptors. These results suggest that ATP, acting through P2Z purinoceptor-mediated phospholipase D, may produce a Ca2+-independent protein kinase C. Heterologous desensitization of muscarinic receptors by protein kinase C may shorten the duration and decrease the magnitude of acetylcholine-induced Ca2+ release.

Acetylcholine↗
PubMed1999

Significance of multi-drug-resistant proteins in predicting chemotherapy response and prognosis in epithelial ovarian cancer.

OBJECTIVES: To clarify the expression of multi-drug-resistant (MDR) markers, GST-pi, c-Jun, P-glycoprotein (Pgp), and MDR-associated protein (MRP) in epithelial ovarian cancer, and to determine whether their expression is predictive of chemotherapy response and patient prognosis. METHODS: Specimens of 58 epithelial ovarian cancer cases obtained at initial surgery were studied immunohistochemically using antibodies. RESULTS: Overall positive rates in the 58 specimens were 58.6% for GST-pi, 44.8% for c-Jun, 27.6% for Pgp, and 22.4% for MRP. The 5-year disease-free survival rate was 26.0% for patients with MRP-positive tumors and 75.2% for those with MRP-negative tumors. The prognosis for those with MRP-positive tumors was significantly poorer (p < 0.05). Patients with GST-pi-positive tumors had a significantly worse prognosis than those with GST-pi-negative tumors (51.9% vs 79.2%, p < 0.05). Multivariate analysis showed that residual tumors 2 cm or larger and MRP expression were independent prognostic factors for chemotherapy resistance. The relative risk of chemotherapy resistance in a patient with a residual tumor 2 cm or larger, positive MRP, and positive GST-pi was 10.6 times greater than the risk in a patient without these factors. CONCLUSION: MRP and GST-pi expression might be potential predictors of the response to standard chemotherapy in epithelial ovarian cancer. Their expression also might contribute to individualizing clinical trials of postoperative chemotherapy.

Antineoplastic Agents↗
PubMed1997

Na+-dependent release of intracellular Ca2+ induced by purinoceptors in parotid acinar cells of the rat.

In rat parotid acinar cells, ATP caused a transient increase in the intracellular Ca2+ concentration ([Ca2+]i) in the absence of external Ca2+. The ATP-induced Ca2+ response was strongly suppressed by removal of external Na+. The sequence of potency in increasing [Ca2+]i was 3'-o-(4-benzoyl) benzoyl-ATP > ATP > uridine 5'-triphosphate (UTP). Adenosine, AMP, ADP or alpha,beta-metylene ATP did not cause an increase in [Ca2+]i. The 3'-o-(4-benzoyl) benzoyl-ATP-induced increase in [Ca2+]i was abolished by removal of external Na+, but the UTP-induced response was not. The threshold external Na+ concentration required for ATP- or 3'-o-(4-benzoyl) benzoyl-ATP-induced Ca2+ release was 10-20 mM. ATP but not UTP caused a rise in the intracellular Na+ concentration ([Na+]i). Ca2+ release stimulated by caffeine or treatment with ryanodine reduced the Ca2+ release evoked by ATP. These results suggest that ATP, acting through P2Z purinoceptors, causes Na+ entry by opening cation-permeable channels, and thereafter the increase in [Na+]i triggers Ca2+ release from ryanodine-sensitive stores. UTP, acting through P2U purinoceptors, causes Ca2+ release independent of external Na+.

Adenosine Triphosphate↗
PubMed1997

The effects of clomiphene citrate on normally ovulatory women.

OBJECTIVE: To investigate the efficacy of clomiphene citrate (CC) on normally ovulatory women who complained of infertility. DESIGN: A randomized study. SETTING: University Hospital. PATIENT(S): Thirty-three normally ovulatory women with unexplained infertility. INTERVENTION(S): Eighteen women received CC at a 50-mg dosage. Fifteen women received no ovulation-induction drugs. MAIN OUTCOME MEASURES: The pregnancy rate (PR) per patient, the PR per cycle, and the cumulative pregnancy rate. RESULT(S): Seven patients in the CC group stopped taking CC, and observations were terminated because of antiestrogenic effects. The pregnancy rate (PR) per patient and the PR per cycle were significantly decreased (P < 0.005) in the CC group (4 of 18 [22.2%] and 4 of 66 [6.1%], respectively) than in the spontaneous group (11 of 15 [73.3%] and 11 of 52 [21.2%], respectively). Kaplan-Meier tests showed that the cumulative pregnancy rate in the CC group was significantly lower than in the spontaneous group (P < 0.05). Five of seven patients who had stopped taking CC became pregnant in spontaneous cycles. CONCLUSION(S): Administration of CC to normally ovulatory women is not efficacious in terms of increasing the pregnancy rate.

Adult↗
PubMed1997

A catalytic amino acid and primary structure of active site in Aspergillus niger alpha-glucosidase.

The catalytic amino acid residue of Aspergillus niger alpha-glucosidase (ANGase) was identified by modification with conduritol B epoxide (CBE), a mechanism-based irreversible inactivator. The inactivation by CBE followed pseudo-first order kinetics. The interaction of CBE and ANGase conformed to a model with a reversible enzyme-inhibitor complex formed before covalent inactivation. A competitive inhibitor, Tris, decreased the inactivation rate. The incorporation of one mole of CBE per mole of ANGase was completely abolished the enzyme activity. A dissociated carboxyl group (-COO-) in the active site was suggested to attack the C-1 of CBE. ANGase was composed of two subunits (P1 and P2), of which P2 was modified by CBE. The labelled residue was included in a peptide (LY3) that was obtained from Lys-C protease digestion of CBE-bound P2. The sequence analysis of CBE-labelled LY3 showed that an Asp was the modified residue, that is, one of the catalytic amino acid residues of ANGase. The primary structure of LY3 was determined by analyzing the sequence of peptide fragments prepared by several proteases.

Amino Acid Sequence↗
PubMed1996

Role of extracellular Ca2+ in acetylcholine-induced repetitive Ca2+ release in submandibular gland acinar cells of the rat.

Acetylcholine (ACh) caused repetitive transient Cl- currents activated by intracellular Ca2+ in single rat submandibular grand acinar cells. As the concentration of ACh increased the amplitude and the frequency of the transient Cl- currents increased. These responses occurred also in the absence of extracellular Ca2+ but disappeared after several minutes. Repetitive transient Cl- currents were restored by readmission of Ca2+ to the extracellular solution. The higher the concentration of extracellular Ca2+ readmitted, the larger the amplitude of the transient Cl- currents. Ca2+ entry through a store-coupled pathway was detected by application of Ca2+ to the extracellular solution during a brief cessation of stimulation with ACh. In these experiments too, the higher the concentration of Ca2+, the larger the transient Cl- currents activated by Ca2+ released from the stores. The time course of decrease in total charge movements of repetitive transient responses to ACh with removal of extracellular Ca2+ depended on a decrease in charge movements of each transient event rather than a decrease in frequency of the repetitive events. The decrease of charge movements of each transient event was due to a decrease in its amplitude rather than its duration. The results suggest that in this cell type and amplitude-modulated mechanism is involved in repetitive Ca2+ release and that Ca2+ entry is essential to maintain the repetitive release of Ca2+. The results further suggest that the magnitude of Ca2+ entry determines the number of unitary stores filled with Ca2+ which can synchronously respond to ACh.

Acetylcholine↗
PubMed1996

Depletion of ryanodine-sensitive Ca2+ store activates Ca2+ entry in rat submandibular gland acinar cells.

The existence of ryanodine-sensitive Ca2+ stores and their role in the Ca2+ entry mechanism were examined in the rat submandibular gland acinar cells, using the microfluorimetry of intracellular Ca2+ concentration ([Ca2+]i). In the presence of thapsigargin, a Ca(2+)-ATPase inhibitor of inositol (1, 4, 5) triphosphate (InsP3)-sensitive Ca2+ stores, caffeine caused an increase in [Ca2+]i, which was inhibited by treatment with ryanodine (a ligand to the Ca(2+)-induced Ca2+ release channels). In the cells treated with ryanodine, 1 mM Ca2+ addition to a Ca(2+)-free solution caused a marked increase in [Ca2+]i, which was eliminated by application of Ni2+ or SK & F 96365, suggesting a Ca2+ entry triggered by ryanodine. The maximal change in the net increase in [Ca2+]i caused by the ryanodine-coupled Ca2+ entry, was 104.0 +/- 16.0 nM, which intense was caused by 10 microM ryanodine. Emptying the InsP3-sensitive stores by treatment with thapsigargin also caused Ca2+ entry, which maximally changed [Ca2+]i by 349.6 +/- 15.1 nM. Ten mumol/liter ryanodine was confirmed to cause a release of 45Ca2+ from the parotidic microsomal fraction enriched in endopalsmic reticulum. We propose that ryanodine-sensitive Ca2+ stores are present in rat submandibular gland acinar cells. We further propose that release of Ca2+ from the ryanodine-sensitive stores, which means eventually depletion of the ryanodine-sensitive Ca2+ stores, can activate the Ca2+ entry. The ability for Ca2+ entry coupled with the ryanodine-sensitive Ca2+ stores seems to be about 30% of the ability for Ca2+ entry coupled with the thapsigargin-sensitive Ca2+ stores.

Animals↗
PubMed1996

[Expression of glutathione S-transferase pi and numerical aberration of chromosome 11 in human ovarian cancer as a prognostic indicator].

In 33 patients with primary ovarian cancer who had not received any chemotherapy before surgery, expression of glutathione S-transferase pi (GST-pi) was studied immunohistochemically in relation to the response to chemotherapy with CDDP, and furthermore it was examined whether numerical aberration of chromosome 11 was available as a prognostic indicator. The obtained results were as follows: 1. Of 33 ovarian cancer tissue samples, 19 (57.6%) showed positive staining and 14 (42.4%) negative staining for GST-pi. 2. The 5 year survival rate of the patients with GST-pi positive tumors was significantly lower than that of those with GST-pi negative tumors (p < 0.01). 3. The frequency of detection of cells showing numerical aberration of chromosome 11 in tissues was significantly higher in ovarian cancers than in benign ovarian tumors and normal ovaries. 4. The 5 year survival rate of the patients with ovarian cancer in which the cells showing numerical aberration of chromosome 11 at 20% or more was significantly lower than that of those in which such cells were under 20% (p < 0.02). These results show that expression of GST-pi and numerical aberration of chromosome 11 in the tissues of human ovarian cancers are useful as prognostic indicators.

Chromosome Aberrations↗
PubMed1995

Galactosylgloboside expression in seminoma. Inverse correlation with metastatic potential.

BACKGROUND: Altered glycosylation is a common phenotype expressed in essentially all types of human cancer and has been found to be correlated closely with the invasive and metastatic properties of a given tumor. Because there was no prognostic information concerning aberrant glycosylation of seminoma, the authors studied this topic. METHODS: Glycosphingolipid (GSL) composition of orchiectomy samples of seminoma were analyzed systematically. GSL patterns from seminoma samples of the following three groups were compared after a 44-month postoperative period: Stage I disease with no evidence of metastasis during the 44-month postoperative period, Stage I with metastatic relapse during this period, and Stage II with retroperitoneal lymph node metastasis. Unknown GSLs detected were analyzed chemically by 1H-nuclear magnetic resonance spectroscopy and mass spectrometry. RESULTS: All nonmetastatic seminomas (n = 12) contained a GSL band that was identified as galactosylgloboside (Gb5; Gal beta 1-->3GalNAc beta 1-->3Gal alpha 1-->4 Gal beta 1-->4Glc beta 1-->1Cer). All metastatic seminomas (n = 5) lacked this GSL, although the sample sizes were admittedly small. CONCLUSION: Only the presence or absence of galactosylgloboside (Gb5), but of no other GSL or gangliosides, clearly correlated with metastatic potential in patients with seminoma. This observation is useful in the estimation of prognosis of patients with seminoma, especially those with Stage I disease.

Adult↗
PubMed1995

Antimicrobial stress compounds from Hypochoeris radicata.

The exudates of Hypochoeris radicata leaves stressed with cupric chloride afforded two eudesmane- and guaiane-type sesquiterpenes, and two alkenals, (2E,4E)-6-hydroxyhexadienal and (2E,4E)-hexadienedial (mucondialdehyde). Their structures were determined by spectroscopic and synthetic methods.

Antifungal Agents↗
PubMed1995

Ca2+ entry through the store-mediated pathway directly activates only the K+ current but the subsequent Ca2+ release from the store activates both K+ and Cl- currents in submandibular gland acinar cells of the rat.

The store-mediated Ca2+ entry was detected in single and cluster of rat submandibular acinar cells by measuring the Ca2+ activated ionic membrane currents. In the cells where intracellular Ca2+ was partly depleted by stimulation with submaximal concentration of acetylcholine (ACh) under a Ca2(+)-free extracellular condition, an employment of external Ca2+ in the absence of ACh caused a sustained increase of the K+ current without affecting the Cl- current. A renewed ACh challenge without external Ca2+ caused repetitive spikes of both K+ and Cl- currents due to the Ca2+ release. SK & F 96365 inhibited the generation of the sustained K+ current and refilling of the Ca2+ store following the Ca2+ readmission. It is suggested that the Ca2+ enters the cell through the store-mediated pathway new the K+ channels and is taken up by the store. Thus, only Ca2+ released from the store can activate both the K+ and Cl- currents.

Acetylcholine↗
PubMed1995

Sr2+ can pass through Ca2+ entry pathway activated by Ca2+ depletion, but can be hardly taken up by the Ca2+ stores in the rat salivary acinar cells.

When Sr2+ was introduced to the external solution after the depletion of Ca2+ from stores of submandibular acinar cells by ACh stimulation, Sr2+ entered cytoplasm of the cell, like the case of Ca2+. SK&F 96365, a Ca2+ channel blocker, or Ni2+ blocked this divalent cation entry. Sr2+ entering the cell continued to increase to a steady level, after the cessation of stimulation, when Sr2+ was present in the external solution, unlike the case of Ca2+. Ca2+ entered cells which had been stimulated with ACh in Sr(2+)-containing external solution. In the cells to which Sr2+ has been applied after the store depletion with ACh, Sr2+ cannot be released by the renewed ACh stimulation, unlike the case of Ca2+. 89Sr2+ uptake by the parotidic microsomal fraction 100 min after addition of ATP was 15.08 +/- 0.70 nmol/mg protein, whereas 45Ca2+ uptake was 144.19 +/- 16.93 nmol/mg protein. It was concluded that in the salivary acinar cells Sr2+ can be a substituent for Ca2+ in the mechanism of entry from the extracellular fluid but cannot be in the mechanism of uptake into the stores.

Animals↗
PubMed1995

Stimulated Ca2+ entry activates Cl- currents after releasing Ca2+ from the intracellular store in submandibular gland cells of the rat.

In order to examine whether Ca2+ entry is directly involved in controlling exocrine secretion, the Ca(2+)-activated Cl- currents were recorded in single and clusters of rat submandibular gland cells using the whole-cell patch-clamp method. Extracellularly applied acetylcholine (ACh, 10 nM) as well as intracellularly applied GTP gamma S and InsP3 caused repetitive transients of the Cl- currents activated by intracellular Ca2+. These responses occurred also in the absence of external Ca2+, but disappeared after several minutes. Readmission of Ca2+ to the extracellular solution restored the repetitive current transients, while introduction of Sr2+ failed to restore the current signals in spite of the presence of Sr2+ entry detected by microfluorimetry. On the other hand, direct application of Sr2+ to the cell inside caused activation of the Cl- currents although less effectively than Ca2+. When Ca2+ was introduced to the extracellular solution during an interruption of ACh stimulation after the ACh-induced depletion of intracellular Ca2+ store, the Cl- current was not elicited. However, a subsequent challenge with ACh at the same concentration in the absence of extracellular Ca2+ caused repetitive transient Cl- currents. The results suggest that in this cell type the stimulated Ca2+ entry does not by itself activate the Cl- currents but activates them indirectly by triggering Ca2+ release from the intracellular Ca2+ store which may take up Ca2+ soon after the Ca2+ entry.

Acetylcholine↗
PubMed1994

Modulation of ischemia-reperfusion-induced hepatic injury by Kupffer cells.

To elucidate the role of Kupffer cells in ischemia-reperfusion-induced hepatic injury, hepatic injury induced by ischemia-reperfusion was analyzed after modulation of Kupffer cell function. Ischemia of the liver was performed by occlusion of both the portal vein and hepatic artery, which enter into the left lateral and median lobes of the liver. Blood flow in the ischemic lobe was reduced, in contrast to an increased blood flow in the nonischemic lobe during occlusion of the veins. Although hepatocyte damage was not demonstrated by ischemia for < 60 min, hepatic injury was found after reperfusion of the liver, and activation of Kupffer cells was morphologically demonstrated by electron microscopies. Suppression of Kupffer cells, induced by previous administration of gadolinium chloride or latex particles, reduced the grade of hepatic injury induced by ischemia-reperfusion. On the other hand, stimulation of Kupffer cell phagocytosis, induced by administration of latex particles at the time of reperfusion, aggravated the ischemia-reperfusion-induced hepatotoxicity, which was then reduced by simultaneous administration of superoxide dismutase. Kupffer cells, isolated from the rats treated with the ischemia-reperfusion procedure, have been found to release increased amounts of oxygen radical intermediates. These results suggest that hepatic injury induced by ischemia-reperfusion is modulated by the function of Kupffer cells and that superoxide anion released from Kupffer cells could play an important role in ischemia-reperfusion hepatic injury.

Animals↗
PubMed1994

Plasma peroxidized low-density lipoprotein with hydroperoxidized cholesteryl linoleates estimated in patients with familial hypercholesterolemia.

A study was conducted to ascertain the presence of peroxidized low-density lipoprotein (LDL) in plasma and to determine the chemical structure of the peroxidized LDL so that the mechanism by which vascular complications develop may be elucidated in patients with familial hypercholesterolemia (FH). Family trees showing hypercholesterolemia and moderate grade thickness of the Achilles' tendon were confirmed in all patients. Cholesteryl ester, triglycerides (TG), free fatty acid (FFA), free cholesterol (FC), and phospholipids in normal LDL were stained on a thin-layer chromatography (TLC) plate, but from peroxidized LDL, spot X1 between TG and FFA, and spot X2 between FFA and FC were identified clearly except for the lipids recognized in normal LDL on the TLC plates. From intermediate-density lipoprotein (IDL), LDL1, and LDL2 of FH patients, spot X1 was clearly recognized. Hydroperoxidized cholesteryl linoleate (HPO-CL) was estimated and identified from Cu(2+)-treated standard CL, Cu(2+)-treated LDL and LDL obtained from FH patients by means of high-pressure liquid chromatography, mass spectrometry, nuclear magnetic resonance, positive reaction of p-methoxydiphenylpyrenyl-phosphine and various chemical reactions. The percentage of HPO-CL to total lipids in LDL was in the order of IDL < LDL1 < LDL2 in FH patients, and it was markedly higher in FH patients when compared to healthy persons. Spot X1 obtained from Cu(2+)-treated CL, from Cu(2+)-treated normal LDL and from LDL of FH patients was chemically identical, consisting of at least 4 kinds of HPO-CL isomer. LDL2-cholesterol levels were higher in FH patients than those of LDL1-cholesterol, whereas in healthy persons LDL1 cholesterol levels were higher compared to those of LDL2 cholesterol. The capacity of LDL2 for peroxidization by Cu2+ was greater than that of LDL1 in healthy persons. Biological functions, such as acceleration of platelet aggregation, great internalization into macrophages and injuries of the arterial endothelia, were reported for LDL with HPO-CL in our previous experiments. Thus, the existence of peroxidized LDL with HPO-CL may be one of the important risks for vascular complications in FH patients.

Adult↗
PubMed1994

Malignant pleural mesothelioma presenting as achalasia.

A 65-year-old man with an occupational history of asbestos exposure developed dysphagia and vomiting. Clinical examinations at onset revealed a dilated esophagus with smooth narrowing at the gastroesophageal junction and no apparent tumor in and around the esophagus. Achalasia was suspected. Dysphagia progressed gradually and examinations performed three months after the onset disclosed a tumor in the pleural and the peritoneal cavities. At laparotomy, the tumor extended from the pleural cavity into the peritoneal cavity. Histological examination of the biopsied specimen demonstrated malignant mesothelioma. We report the first case of malignant pleural mesothelioma presenting as achalasia.

Aged↗