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Biomedical subjects

Y Shintani

Publications and source records attributed to Y Shintani.

At least 73 records · Page 4Linked to original sources
PubMed1996

Regulation of chloride channel trafficking by cyclic AMP via protein kinase A-independent pathway in A6 renal epithelial cells.

The apical membrane of renal epithelial A6 cells has 3 and 8 pS Cl- channels. Both types of the channels were blocked by NPPB (5-Nitro-2-(3-phenylpropylamino)-benzoic acid; 100 microM). 8-bromo-cAMP (Br-cAMP) increased the open probability of 3 pS Cl- channel and this action was inhibited by pretreatment with H89, an inhibitor of cAMP-dependent protein kinase (PKA). On the other hand, the number of 8 pS Cl- channel was increased by Br-cAMP. The increase in number of 8 pS Cl- channel by Br-cAMP was inhibited by brefeldin A (a blocker of movement of membrane protein from an intracellular pool to the cell surface) but not by H89. These observations indicate that cAMP could activate the 3 pS Cl- channel through PKA-dependent phosphorylation, and that cAMP could stimulate translocation of the 8 pS Cl- channel through PKA-independent pathways. We conclude that PKA-independent pathways are involved in cAMP signaling mechanisms in addition to PKA-dependent pathways.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Regulation of single Cl- channel conductance by insulin and tyrosine phosphatase.

The apical membrane of distal nephron epithelium (A6) had a Ca(2+)-activated outwardly rectifying Cl- channel with single-channel conductances of 3 pS for outward current and 0.8 pS for inward current. The single-channel conductance for inward current was dependent on cytosolic Ca2+ concentration. Insulin increased the single-channel conductance for the inward current by increasing Ca2+ sensitivity about 300-fold. The insulin action was diminished by vanadyl hydroperoxide (vanadate, an inhibitor of protein tyrosine phosphatase (PTP)). Application of protein tyrosine kinase, p60c-src, reversibly diminished the insulin-induced increase in single-channel conductance. Further, the application of PTP to the cytosolic surface of the inside-out patch membrane, like insulin, increased single-channel conductance. PTP-mediated dephosphorylation of the phospho-tyrosine of the channel protein, as a mechanism of intracellular signaling of insulin action, is a novel mechanism for regulating single-channel conductance by modulating Ca2+ sensitivity.

Animals↗
PubMed1996

Roles of tyrosine kinase in insulin action on cell volume of fetal rat type II pneumocyte.

The aim of the present study was to investigate the roles of tyrosine kinase (TK) in the insulin action on cell volume in fetal rat (20-day gestational age) type II pneumocyte. Insulin (100 nmol/l) increased cell volume, and this insulin (100 nmol/l) action was completely blocked by 50 micromol/l bumetanide (BMT) and 10 micromol/l amiloride (AML). This observation indicates that 100 nmol/l insulin activates BMT-sensitive Na+/K+/2Cl- cotransporter and AML-sensitive pathways. The stimulatory action of 100 nmol/l insulin on BMT-sensitive Na+/K+/2Cl- cotransporter was completely abolished by 10 micromol/l lavendustin A (LAV-A, an inhibitor of TK), however 100 nmol/l insulin could stimulate AML-sensitive pathways even in LAV-A (10 micromol/l)-treated cells. These observations indicate that the insulin (100 nmol/l) action on the BMT-sensitive Na+/K+/2Cl- cotransporter is mediated through TK-dependent pathways, while 100 nmol/l insulin requires a TK-independent pathway to show the stimulatory action on the AML-sensitive pathways. From these observations we conclude that TK-dependent and -independent pathways are involved in the insulin (100 nmol/l) signaling in fetal rat type II pneumocyte.

Amiloride↗
PubMed1996

Prolonged fecal excretion of hepatitis A virus in adult patients with hepatitis A as determined by polymerase chain reaction.

In hepatitis A virus (HAV) infection, fecal excretion of the virus has been reported to cease shortly after symptoms occur. Although there have been several reports on detection of HAV in feces using polymerase chain reaction (PCR), the duration of fecal HAV shedding in human adult hepatitis A has not been well described. In the present study, we applied the reverse-transcription (RT)-PCR system to the detection of fecal HAV RNA in 10 patients with sporadic hepatitis A. The viral genomic RNA was detected in the stools from five patients after the onset of clinical symptoms. All stool samples collected within 10 days of onset of illness were HAV-RNA-positive, and the duration of positivity lasted from a few days to as long as 3 months. In four patients, HAV RNA was detected in the stool even after the serum alanine transaminase (ALT) levels had peaked, and in one patient well after ALT levels fell to normal. These results show that fecal shedding of HAV can last for months after resolution of symptoms and such patients could be a source of further spreading of the virus in the community.

Adult↗
PubMed1996

Immunoradiometric assay for follistatin: serum immunoreactive follistatin levels in normal adults and pregnant women.

A sensitive and specific immunoradiometric assay for follistatin was developed using antifollistatin mouse monoclonal and rabbit polyclonal antibodies. The sensitivity of the assay was 0.5 micrograms/L, and cross-reactivities with recombinant human activin A and bovine inhibin were less than 0.1%. The intra- and interassay coefficients of variation were less than 10%, and the recovery rate was about 90% in human serum. The addition of activin A to the same sample resulted in a minimal influence on follistatin recovery, indicating that this assay system can measure the total level of activin-bound and unbound follistatin. Gel filtration analysis of human serum showed that the majority of immunoreactivity was eluted in a larger molecular size position than that of free follistatin, suggesting that the large part of follistatin is bound to other proteins, presumably activins, in serum. Using this assay, immunoreactive follistatin levels in various biological fluids and human sera were examined. The dose-response curves of porcine follicular and amniotic fluids were parallel to the standard curve, and porcine follicular fluid contained extremely high follistatin immunoreactivity (5.6 mg/L). The serum follistatin level in normal human volunteers was 13.3 +/- 4.7 micrograms/L (mean +/- SD; n = 60), with a tendency to increase gradually with age. On the other hand, the serum follistatin level was remarkably elevated in pregnant women (62.7 +/- 35.3 micrograms/L; n = 57), with a positive correlation with weeks of pregnancy. These data indicated that circulating immunoreactive follistatin is detectable in human serum, and the levels vary with physiological conditions such as aging and pregnancy.

Activins↗
PubMed1996

Serum immunoreactive activin A levels in normal subjects and patients with various diseases.

We developed and validated a RIA for measuring serum activin A. The least detectable value of this assay was 0.1 micrograms/L, and the antibody used cross-reacted slightly with bovine inhibin (3.2%) and porcine activin AB (10.0%) but not with porcine activin B (< 0.5%). Serum activin A was extracted with acetonitrile and trifluoroacetic acid to get rid of the interaction with possible binding proteins in serum. As a result of this extraction procedure, the dose-response curve of serum extract was parallel to the standard curve and a single immunoreactive (ir-) peak was demonstrated on gel chromatographic analysis with constant recovery rates over 80%. Serum ir-activin A level in healthy adults was 1.27 +/- 0.03 micrograms/L (mean +/- SEM, n = 180); being 1.38 +/- 0.05 micrograms/L (n = 90) in male, and 1.16 +/- 0.05 micrograms/L (n = 90) in female subjects, with a tendency to increase with age. Serum ir-activin A level during pregnancy showed a marked increase with the advance of gestation; 1.65 +/- 0.41 micrograms/L (n = 7) in the early, 4.50 +/- 1.13 micrograms/L (n = 21) in the middle, and 16.32 +/- 2.25 micrograms/L (n = 26) in the late trimester, with a rapid decline after delivery. On the other hand, serum ir-activin A level was elevated in patients with hyperthyroidism (1.91 +/- 0.37 micrograms/L, n = 31), liver cirrhosis (2.03 +/- 0.71 micrograms/L, n = 10), chronic renal failure (3.41 +/- 0.34 micrograms/L, n = 41), and advanced solid cancer (2.24 +/- 0.52 micrograms/L, n = 67). These findings indicate that serum ir-activin A level varies with physiological conditions such as aging and pregnancy, and that it may reflect the altered production and metabolism of activin A in certain diseased conditions.

Activins↗
PubMed1996

Effects of LHRH, FSH and activin A on follistatin secretion from cultured rat anterior pituitary cells.

We demonstrated the release of follistatin, an activin-binding protein, from cultured rat anterior pituitary cells by measuring immunoreactive (ir-) follistatin in a specific immunoradiometric assay. Ir-follistatin release gradually increased in cultures over 1-18 days and reached its maximal level at 12-15 days of incubation. The basal ir-follistatin levels in the culture media increased about 3- (P < 0.01) and 5-fold (P < 0.001) in 2 and 10% fetal calf serum for 6 days, respectively. LHRH and activin A caused an approximately 2.0- (P < 0.05) and 1.8-fold (P < 0.05) rise in ir-follistatin release, respectively, in contrast to the lack of significant FSH effects. The culture medium condensed on sulfate-cellulofine gel was resolved by polyacrylamide gel electrophoresis and blotted with anti-follistatin polyclonal antibody, resulting in at least three protein bands ranging from 35 to 50 kDa under non-reducing conditions. These results indicated that follistatin is produced in anterior pituitary cells and that its secretion is regulated at least in part by LHRH and activin, implying an autocrine/paracrine role of activin and follistatin in the pituitary.

Activins↗
PubMed1996

Immunohistochemical localization of activin A and follistatin in human tissues.

We immunohistochemically investigated the localization of activin A and follistatin in various human tissues with specific antibodies to recombinant human (rh-) activin A and rh-follistatin. Specific immunostaining of activin A was detected in Leydig and Sertoli cells of the testis. In the ovary, granulosa cells of mature follicle and luteal cells of the corpus luteum stained for activin A. Immunoreactive activin A was present in somatotrophs of the pituitary gland and insulin-positive B cells of the pancreatic islets. Immunoreactivity for activin A was also found in thyroid follicular cells, adrenocortical cells, neuronal cells of the cerebrum and monocytoid cells in the bone marrow. Follistatin, an activin-binding protein, was immunostained in the same tissues as activin A. These findings indicated that activin A and follistatin are widely distributed in human tissues, suggesting that activin plays important roles as a common regulator in various tissues under the control of co-existing follistatin.

Activins↗
PubMed1996

Regulation of immunoreactive activin A secretion from cultured rat anterior pituitary cells.

Immunoreactive activin A (ir-activin A) release from cultured rat anterior pituitary cells was examined by measuring ir-activin A in culture medium by a specific radioimmunoassay. Ir-activin A release into the medium increased over 1-18 days, and reached a maximal level at 12-15 days. The basal levels of ir-activin A in the culture media were 0.70 +/- 0.10 (mean +/- SD), 1.30 +/- 0.36 and 1.83 +/- 0.44 ng/10(6) cells, when cultured for 6 days with 0, 2 and 10% fetal calf serum, respectively. LHRH induced an approximate 1.4-fold increase in ir-activin A release in contrast to a 40-60% inhibition with FSH, but LH did not affect the activin A release. In the presence of 12-o-tetradecanoylphorbol acetate (TPA), iractivin A release was enhanced, but no significant effect was induced by forskolin. Activin A was distinctly immunostained in cultured rat anterior pituitary cells. These results suggested that activin A release from the pituitary is modified by FSH and LHRH, and that the activation of protein kinase C may be involved in the action of LHRH.

Activins↗
PubMed1996

A case report of an elderly patient with acromegaly.

We encountered a 91-year-old patient with acromegalic features. The serum levels of growth hormone (GH) and insulin-like growth factor-I (IGF-I) were increased to 23.3 ng/ml and to 268 ng/ml, respectively. Both thyrotropin-releasing hormone and luteinizing hormone-releasing hormone tests demonstrated a 2-3 fold increase in the serum GH level. Magnetic resonance imaging disclosed a pituitary mass in the enlarged sella. The patient was diagnosed as having acromegaly due to overproduction of GH from a pituitary tumor. She manifested cardiac hypertrophy with severe aortic stenosis and mild hypertension, but without diabetes mellitus. After the administration of octreotide subcutaneously at a dose of 25 to 50 micrograms daily for 20 days, the serum GH level increased transiently but decreased rapidly to approximately half the initial level, and suppression of the GH level persisted thereafter for over 2.5 months. This patient seems to be the oldest patient with acromegaly among those reported in Japan.

Acromegaly↗
PubMed1996

Determination of free follistatin levels in sera of normal subjects and patients with various diseases.

We developed an assay system for measuring free follistatin by using an anti-follistatin mouse monoclonal antibody and [125I]activin A. The sensitivity of this assay was 0.5 microgram/l and cross-reactivities with inhibin, luteinizing hormone, follicle-stimulating hormone and growth hormone were all less than 0.5%. The dose-response curves of human sera and follicular fluid were parallel to the standard curve, and the follicular fluid contained a large amount of follistatin (6.4 +/- 0.5 mg/l, mean +/- SEM; N = 13). The within- and between-assay coefficients of variation calculated from the analysis of serum samples of four different concentrations were 3.3-7.8% and 3.9-11.0%, respectively. The recovery rates of free follistatin at five different doses were 86.4 - 102.4%. When activin A was added to the same sample, free follistatin recovery rate declined dose-dependently. Gel filtration analyses of human serum and follicular fluid resulted in a single peak corresponding to authentic follistatin. Using this assay, free follistatin concentrations in sera were measured in normal, pregnant and diseased subjects. The free follistatin level in serum of normal adults was 3.5 +/- 0.2 micrograms/l (N = 60), which was significantly elevated in pregnant women (16.7 +/- 1.3 micrograms/l, N = 56), and in patients with chronic liver disease (8.1 +/- 1.1 micrograms/l, N = 20), chronic renal failure (6.7 +/- 0.9 micrograms/l, N = 42), advanced solid cancer (8.5 +/- 1.0 micrograms/l, N = 39) and hematological malignancies (6.8 +/- 1.0 micrograms/l, N = 18). These data indicated that the free follistatin concentration in serum is detectable and varies during pregnancy and in various diseased states.

Adult↗
PubMed1996

Double pituitary adenoma--two case reports.

A 43-year-old male and a 39-year-old male presented with multiple pituitary adenomas with two distinct histological types. The first patient who had multiple endocrine neoplasia type 1 had developed acromegaly due to a growth hormone-releasing hormone (GHRH)-producing pancreatic tumor. Both plasma GHRH and growth hormone (GH) levels decreased to normal after resection of the pancreatic tumor. However, the plasma GH level gradually increased again and magnetic resonance imaging revealed pituitary adenoma formation. Histological examination revealed two different histological types of pituitary adenoma: GH cell adenoma and null cell adenoma. The second patient, with no such genetic condition, had a non-functioning pituitary adenoma. Histological examination revealed two different histological types of silent GH cell adenoma and silent gonadotroph adenoma. Careful histological examination is required to exclude the possibility of multiple pituitary adenomas.

Adenoma↗
PubMed1995

Difficulties of families with handicapped children after the Hanshin-Awaji earthquake.

In order to clarify the difficulties which handicapped people experienced in the Hanshin-Awaji earthquake disaster, 678 families with handicapped children were studied 1.5 months after the earthquake. All the students who were enrolled in this study were going to some type of school or training classes for handicapped children in January 1995. The study was completed between 1 and 10 March. The questionnaires which were designed for this study consisted of three parts: the difficulties which the families were faced with, their requirements for social and medical services and the symptoms and reactions of their children after the earthquake. A total of 466 answers were obtained from their parents. The kinds of difficulties differed between the families of mentally retarded children and those of the physically handicapped. While many parents with physically handicapped children desired better medical information or materials, many parents with mentally retarded children wanted better care services for their children. Physical and psychological effects of the earthquake were only temporary in most cases. However, some of the handicapped children were still suffering from such reactions as of 10 March. From the results of our study it became evident that a systematic relief program for these handicapped people should be established. The relief program should include the distribution of information regarding medical and social services. Psychological reactions such as panic, excitement and suppression of mental activity were still observed in some handicapped children on 10 March. Further observation will therefore be necessary.

Child↗
PubMed1995

Two different pituitary adenomas in a patient with multiple endocrine neoplasia type 1 associated with growth hormone-releasing hormone-producing pancreatic tumor: clinical and genetic features.

The clinical and genetic features of a 43-year-old male patient with multiple endocrine neoplasia type 1 were reported. He developed hyperparathyroidism, a GHRH-producing pancreatic tumor, and acromegaly between 1980 and 1983. Because his pituitary gland increased in size even after resecting the GHRH-producing pancreatic tumor, transsphenoidal hypophysectomy was performed six years later. The pituitary contained two histologically-different adenomas composed of somatotroph cells and null cells. Genetic analyses revealed loss of heterozygosity on chromosome 11 in common in the pituitary adenomas, the pancreatic endocrine tumors, and a parathyroid hyperplasia. On the other hand, mutations of ras, p53, Gs alpha, and Gi2 alpha genes were not found in these tumors. The loss of the tumor suppressor gene on chromosome 11q12-13 was involved in the formation of two pituitary adenomas, two pancreatic endocrine functioning tumors, and a parathyroid hyperplasia in this patient, but the tumorigenic factors in the specific endocrine organs remain to be studied.

Acromegaly↗
PubMed1994

Purification and characterization of two collagenase inhibitors from mouse sarcoma 180 conditioned medium.

We have previously shown that mouse sarcoma 180 cells produce vascular endothelial growth factor [VEGF; Rosenthal et al., 1990, Growth Factors, 4: 53-59], an endothelial mitogen that stimulates angiogenesis. Recent reports have implicated metalloproteinases and their inhibitors in the regulation of vascular morphogenesis, tumor invasion, and metastasis. We report here that mouse sarcoma 180 cells produce two collagenase inhibitors. These inhibitors were purified by heparin-Sepharose affinity chromatography, gel filtration, and C4 reverse phase h.p.l.c. Analytical gel electrophoresis of the purified inhibitors (MS-22 and MS-31) revealed molecular masses of 22,000 and 31,000 Da under reducing conditions, and 20,000 and 30,000 Da under nonreducing conditions, respectively. The NH2-terminal amino acid sequence of MS-22 was identical to that of tissue inhibitor of metalloproteinases type 2 (TIMP-2) produced by human melanoma cells [Stetler-Stevenson et al., 1989, J. Biol. Chem. 264: 17374-17378) over the first 30 amino acids. The NH2-terminal amino acid sequence of MS-31 was identical to that of murine TIMP-1 [Gewert et al., 1989, EMBO J 6:651-657]. Statistical analysis of the amino acid composition data of these two mouse sarcoma 180-derived collagenase inhibitors confirms the identification of MS-22 as TIMP-2 and MS-31 as TIMP-1.

Amino Acid Sequence↗
PubMed1994

Measurement of somatostatin release in rat brain by microdialysis.

We determined the most suitable conditions for measuring the somatostatin (SRIF) level by brain microdialysis and investigated its release from the hypothalamus. The relative recovery rate of SRIF was 8.4 +/- 0.5% (mean +/- SE) using a polycarbonate (PC) membrane with the push-pull method at a flow rate of 2 microliters/min. Using tubes with an internal diameter of 0.28 mm and lengths of 5, 25, 50 and 100 cm, the relative recovery rates using a PC membrane with the push method were 8.2 +/- 0.5%, 7.3 +/- 0.6%, 6.2 +/- 0.5% and 4.1 +/- 0.6%, respectively. When using tubes with an internal diameter of 0.1 mm and lengths of 5, 25, 50 and 100 cm, the relative recovery rates were 7.3 +/- 0.7%, 5.6 +/- 1.0%, 3.5 +/- 1.1% and 1.4 +/- 0.7%, respectively. The relative recovery rate was 5.2 +/- 0.5% with a polysulfone (PS-F, Fresenius) membrane, 4.5 +/- 0.4% with a PS-H (Hospal) membrane, 2.6 +/- 0.2% with an ethylenevinyl alcohol membrane (EVAL), 5.1 +/- 0.8% with a polyvinyl alcohol (PVA) membrane and 10.4 +/- 0.8% with a PS-K (Kaneka) membrane. With the push method, the extracellular SRIF level in rat pituitary was 42.8 +/- 1.8 pg/ml with a PC membrane, 23.1 +/- 2.9 pg/ml with an EVAL membrane at a flow rate of 2 microliters/min. With the push-pull method, it was 52.7 +/- 5.2 pg/ml using a PC membrane, 33.5 +/- 2.8 pg/ml using a PVA membrane and 54.4 +/- 3.2 pg/ml using a PS-K membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics↗
PubMed1994

Lung cancer containing growth hormone-releasing hormone associated with hypertrophic osteoarthropathy. Case report.

In a 49-year-old man, large-cell carcinoma of the lung was accompanied by raised serum levels of growth hormone (GH) and growth hormone-releasing hormone (GHRH) and hypertrophic osteoarthropathy. Immunohistochemically the tumour contained GHRH but not GH. The osteoarthropathy disappeared after resection of the primary tumour and did not reappear after its recurrence. The high serum GH level presumably was due to ectopic GHRH production in the tumour. The hypertrophic osteoarthropathy was not clearly attributable to these hormones.

Carcinoma, Non-Small-Cell Lung↗