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Biomedical subjects

N Miyamoto

Publications and source records attributed to N Miyamoto.

At least 19 recordsLinked to original sources
PubMed1992

Modification of water and electrolyte metabolism during head-down tilting by hypoglycemia in men.

The effect of hypoglycemic stress on the changes in water and electrolyte metabolism induced by head-down tilting (HDT) was studied. Six healthy men were subjected to postural changes (30 min standing, 2 h HDT, 1 h standing), with or without the intravenous administration of insulin at the beginning of HDT. When insulin was not given, antidiuretic hormone (ADH), cortisol, plasma renin activity (PRA), aldosterone, and catecholamine levels were decreased and atrial natriuretic polypeptide (ANP) levels increased during HDT. These changes were associated with 2.5- and 1.5-fold increases in urine flow and sodium excretion, respectively, when compared with the amounts before HDT. On the other hand, insulin-induced hypoglycemia during HDT produced increases in ADH, cortisol, PRA, aldosterone, and catecholamine levels. At the same time, an exaggerated ANP response by HDT was observed. These hormonal changes were associated with an abolishment of the increases in urine flow and sodium excretion. It is suggested that acute stress modifies the changes in fluid and electrolyte metabolism induced by HDT.

Adult↗
PubMed1992

A 3',5'-cyclic adenosine monophosphate-dependent pathway is responsible for a rapid increase in c-fos messenger ribonucleic acid by adrenocorticotropin.

ACTH rapidly and transiently increases c-fos mRNA in the rat adrenals in vivo. The present investigation was undertaken in order to determine what kind(s) of second messenger systems is involved in this increase. Rat adrenal cells were grown in monolayers in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum. After 2 days of culture, cells were treated with ACTH and various agents alone or in combination. The amount of c-fos mRNA was determined by dot blot hybridization and corticosterone levels in the media were measured by RIA. ACTH (300 pg/ml) increased c-fos mRNA transiently with a peak level after 60 min. A similar increase was observed when (Bu)2cAMP (1 mM) was substituted for ACTH. Pretreatment with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide (H-89), a selective inhibitor of cAMP-dependent protein kinase, suppressed both basal and ACTH-increased c-fos mRNA. H-89 also suppressed corticosterone production. On the other hand, neither 12-O-tetradecanoyl-phorbol-13-acetate (100 ng/ml) nor elevated potassium ion (50 mM) affected the amount of c-fos mRNA and corticosterone production. Furthermore, pretreatment with cycloheximide (5 micrograms/ml) increased both basal and ACTH-increased c-fos mRNA. These results indicate that ACTH increases c-fos mRNA by phosphorylation of preexisting trans-acting factor(s) via cAMP-dependent protein kinase in common with steroidogenesis.

Adrenal Glands↗
PubMed1992

Spontaneous coronary artery dissection after a natural course for 10 years--a case report.

We encountered a patient with spontaneous coronary artery dissection complicated by acute inferior myocardial infarction. A 58-year-old male was admitted to our hospital due to acute inferior myocardial infarction in 1979. Coronary angiography performed 4 weeks after the onset showed a double lumen divided by a linear intimal flap in the right coronary artery, suggesting coronary artery dissection, but no apparent occlusion. Subsequently, he had been medicated with nitrates without any recurrent infarction. In February, 1989, 10 years after the first examination, coronary angiography was again performed and showed that the dissection had remained unchanged. Acetylcholine infusion into the right coronary artery induced coronary spasm. The prognosis of this condition seems to be better than has been generally considered, particularly in patients such as ours in whom the involvement of coronary spasm in the development of coronary artery dissection and myocardial infarction is suggested. When coronary spasm in controlled by treatment with nitrates or calcium antagonists, an uneventful course may be expected.

Acetylcholine↗
PubMed1992

ACTH increases expression of c-fos, c-jun and beta-actin genes in the dexamethasone-treated rat adrenals.

Our recent finding that ACTH increases c-fos mRNA in the adrenal gland of hypophysectomized rats indicates that the gene product FOS may play an important role(s) in mediating the action of ACTH. However, hypophysectomy employed in that study causes the disappearance of trophic hormones other than ACTH and may modify the effect of ACTH. Thus, in the present investigation, dexamethasone-treated rats were used. Since FOS functions only when it dimerizes with JUN (the product of c-jun gene), the changes in the levels of c-fos and c-jun mRNAs were studied together with that of beta-actin mRNA which is also affected by ACTH. Northern blot analysis was employed to determine the mRNA levels. It was demonstrated that ACTH increases the mRNAs coding c-fos and c-jun in the adrenal glands of dexamethasone-treated, ACTH-suppressed rats. The c-fos mRNA was not detectable before ACTH administration. After ACTH administration, the mRNA levels were transiently increased, the maximum level being observed at 30 min after ACTH. At 180 min post ACTH, the level returned to the unstimulated level. The mRNA coding c-jun was detectable before ACTH administration and it also increased rapidly after ACTH with maximal stimulation at 30 min. However, the mRNA level at 180 min post ACTH was still higher than the unstimulated level. The changes in beta-actin mRNA were approximately the same as those of c-jun mRNA. These results suggest that increased expression of c-fos, c-jun and beta-actin genes by ACTH may play an important role in mediating its action on the adrenals.

Actins↗
PubMed1992

Gonadotropin induces expression of c-fos and c-jun genes in rat ovaries.

It has been shown that the expression of protooncogenes, c-fos and c-jun, induced by growth factors and hormones plays important roles in cellular proliferation, tissue differentiation and transcription of certain genes. Since gonadotropin stimulates ovarian steroidogenesis and cellular proliferation, we investigated whether gonadotropin affects the expression of c-fos and c-jun genes in rat ovaries. The expression of mRNA coding side chain cleavage enzyme (P450scc), the rate limiting enzyme in ovarian steroidogenesis was also studied. The effect of gonadotropin was examined in female rats whose gonadotrophs were medically ablated by GnRH agonist (TAP-144-SR). After intravenous administration of pregnant mare's serum gonadotropin (PMSG:30 IU/rat), their ovaries were dissected out at various time intervals and total RNA was extracted. Changes in the levels of c-fos, c-jun and P450scc mRNAs were determined by Northern blot analysis. The levels of c-fos and c-jun mRNAs increased rapidly and transiently with the peak levels at 15 min after PMSG administration. The levels of both mRNAs were decreased by 30 to 60 min. On the other hand, the levels of P450scc mRNA started to increase 60 min after PMSG. These results indicate that gonadotropin-induced increase in the expression of c-fos and c-jun genes may play important roles in mediating the action of gonadotropin on the ovaries.

Actins↗
PubMed1992

[Relationship between the symptomatic cytomegalovirus infection and the fluctuation of anti-CMV antibodies in patient after renal transplantation].

Between Sept.1, 1989 and Feb.28, 1990, 19 patients received renal allografts, and all of them were examined by serological tests for CMV infection before and after the transplantation. Six patients who had some clinical symptoms such as fever and cough were monitored for anti-CMV antibodies by the ELISA method during the first 3 months after the transplantation. Five of the 6 patients complained of mild clinical symptoms but their condition was not serious. The other patients, a 42-year-old man developed serious CMV infection. His serological CMV antibody titer had decreased one month after the transplantation compared to that before the transplantation. By contrast, the other patients showed either elevation or no change of CMV antibody titer. Therefore, special attention should be paid to the case of decrease rather than increase in CMV antibody titer one month after the transplantation in patients with severe symptoms.

Antibodies, Viral↗
PubMed1992

[Inversion of chromosome 16 observed in acute myeloblastic leukemia (M2) with biphenotypic surface markers lacking monocytosis and eosinophilia].

Inversion of chromosome 16 was found in a 73-year-old female with acute myeloblastic leukemia (FAB:M2). Complete remission was achieved by combined chemotherapy (DNR, Ara-C, 6-MP, Prednisolone), but she relapsed 6 months later without CNS involvement and died of respiratory failure presumably due to cerebrovascular accident during remission reinduction chemotherapy. Biphenotypic surface markers (CD2+ and CD13+) were observed on relapse. Eosinophilia was not observed throughout. Our patient and the other reported case suggest that biphenotypism and the lack of eosinophilia and monocytosis in inv (16) leukemia may be correlated with a poor prognosis.

Aged↗
PubMed1992

[A case of large cell carcinoma of the lung which is suspected of producing granulocyte colony-stimulating factor].

A 41-year-old male complaining of fever and left shoulder pain was admitted to our hospital for further examination of an abnormal shadow on chest X-ray film. His laboratory data on admission showed marked leukocytosis and elevation of serum alkaline phosphatase. The diagnosis of large cell carcinoma of the lung was made by percutaneous biopsy and he was staged clinically as T3N0M0. Chemotherapy including CDDP and VDS resulted in resolution of symptoms and normal laboratory data. After three courses of chemotherapy, he underwent left upper lobectomy with chest wall resection. Pathological diagnosis of the resected tumor was large cell carcinoma with giant cells, and he was staged postoperatively as T3N0M0. Since colony stimulating activity was demonstrated in both homogenate of tumor cells and tumor conditioned medium, and preoperative serum granulocyte colony-stimulating factor (G-CSF) was 105 pg/ml, we concluded that leukocytosis in this patient was caused by G-CSF produced by tumor cells. The patient was in good health two years after surgery with no signs of recurrence.

Adult↗
PubMed1992

Surgical excision of hemophilic pseudotumor of the ilium.

The iliac hemophilic pseudotumor is a rare complication of hemophilia occurring in 1-2% of patients with Factor VIII or Factor IX deficiency. It is frequently disabling and life threatening. This report presents a comparative study of postoperative results of two cases of hemophilic pseudotumor of ilium. One patient undergoing partial resection showed a favorable postoperative course, whereas the patient with complete resection of the pseudotumor died of postoperative bleeding and sepsis. Studies on the postoperative results of these two cases indicate that careful preoperative consideration of tumor size and degree of infiltration is of the utmost importance in operative management. Early excision of tumors eliminates the possibility of endogenous infection. Even partial resection of huge tumors, leaving the lateral wall intact for compression, can promote recovery of functions.

Angiography↗
PubMed1991

Diuretics modify [Arg8]vasopressin-stimulated cAMP but not atrial natriuretic peptide-stimulated cGMP formation in renal cells.

The present study was undertaken to examine whether sulfonamide-derived diuretics affect [Arg8]vasopressin (AVP)-stimulated or atrial natriuretic peptide (ANP)-stimulated cyclic nucleotide formation in cells cultured from rat or dog kidney. In rat renal cells, all four sulfonamide-derived diuretics examined significantly suppressed 10(-9) M AVP-stimulated cAMP formation at concentrations of 10(-4) and 10(-3) M, while basal cAMP formation was unchanged by the diuretics. When cells were stimulated with 10(-7) M AVP, low ceiling diuretics (indapamide and trichlormethiazide) did not suppress cAMP formation, while high ceiling diuretics (furosemide and azosemide) significantly suppressed cAMP formation at concentrations of 10(-4) and 10(-3) M. The suppressive effect of the diuretics on AVP-stimulated cAMP formation in vitro paralleled the reported diuretic potency of the agents in vivo. In dog renal cells, all four diuretics significantly suppressed 10(-9) M AVP-stimulated cAMP formation at concentrations from 10(-6) to 10(-5) M, while these diuretics did not change basal cAMP levels. High ceiling diuretics suppressed 10(-7) M AVP-stimulated cAMP formation, whereas low ceiling diuretics did not. The difference in effective doses between rats and dogs seems to be consistent with the species difference observed in vivo. None of the diuretics affected basal levels of intracellular cGMP or ANP-stimulated cGMP formation in cultured rat renal cells. In addition to the inhibition of the Na/K/Cl co-transporter, it is suggested that most sulfonamide-derived diuretics act, at least in part, by inhibiting the actions of AVP.

Animals↗
PubMed1991

Pleomorphic adenoma of the external auditory canal in Japan, with a case report.

A rare case of a 51-year-old female with a pleomorphic adenoma, measuring 0.9 x 0.7 x 0.6 (cm3), originating from the right external auditory canal (EAC), was reported. The authors discussed the 7 reported cases of EAC pleomorphic adenoma in Japan, comparing them with pleomorphic adenomas occurring in the nasal cavity and the parotid gland. It is currently too early to conclude that pleomorphic adenoma in the EAC does not tend to recur or shows a marked tendency toward canceration. The best possible treatment for EAC pleomorphic adenoma at present seems to be, as in cases of tumors in other sites, surgical resection together with removal of a sufficient range of surrounding normal tissue, followed by careful long-term postoperative observation of the clinical course.

Adolescent↗
PubMed1991

Influence of mode of delivery on fetal pituitary-thyroid axis.

We measured the cord serum levels of thyroid-stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) in 922 neonates delivered by mothers who had no thyroid disorders. The T4 and T3 levels increased progressively from the 27th to the 40th week of gestation. However, the TSH levels varied widely and had no correlation with gestational age, because they were affected by the mode of delivery. The mean cord serum TSH level in neonates delivered by vacuum extraction was 16.3 +/- 10.0 microU/ml (n = 30), which was significantly higher than the level following normal vaginal delivery (9.5 +/- 6.0 microU/ml, n = 622) (p less than 0.005). The mean cord serum TSH level following elective caesarean section was 6.5 +/- 3.1 microU/ml (n = 79), and this was significantly lower than after normal vaginal delivery (p less than 0.005). TSH levels in high-risk neonates were significantly higher than in neonates without risk factors. A significant positive correlation was found between the duration of the second stage of labor and the cord serum TSH level (r = 0.45, n = 412, p less than 0.01). However, there was no correlation between the cord serum TSH level and the congenital hypothyroidism screening TSH level (r = 0.01, n = 468). We conclude that the cord serum TSH level reflects delivery stress and that an elevated level does not influence the congenital hypothyroidism screening TSH test in which blood is obtained at five days of life.

Adult↗
PubMed1991

Hyperbaric diuresis is associated with decreased antidiuretic hormone and increased atrial natriuretic polypeptide in humans.

When men are exposed to a hyperbaric environment, urine flow increases. In order to elucidate the mechanism of this hyperbaric diuresis, a dry saturation dive experiment was carried out. Five male subjects were exposed to a 16-21 ATA (atmospheric pressure absolute) helium-oxygen (He-O2) environment for 4 days. Five blood samples were obtained in the early morning (0600-0630 h): once at predive 1 ATA air, 3 times at 16-21 ATA He-O2, and once at postdive 1 ATA air. Eight-hour timed urine samples, 0600-1400 h, 1400-2200 h, and 2200-0600 h (night urine), were collected throughout the experimental period. Urine flow markedly increased by the exposure to hyperbaria in the presence of constant creatinine clearance. The increase was mostly attributable to the urine flow during 2200-0600 h. The secretion of antidiuretic hormone (ADH) was suppressed at daytime and night during the exposure. On the other hand, the secretion of atrial natriuretic polypeptide (ANP) increased solely at night during hyperbaria and correlated with the increases of both the nocturnal urine flow and the nocturnal urinary excretion of sodium. These results suggest that both suppressed ADH secretion and stimulated ANP secretion cause hyperbaric diuresis.

Adult↗
PubMed1991

[A case of ruptured aneurysm of the descending thoracic aorta associated with active Behçet's disease].

A 63-year-old male receiving steroid for active Behçet's disease was admitted of massive hemoptysis. A pseudoaneurysm of about 5 cm in diameter caused by rupture of the aortic wall penetrating into the lung was detected on the descending thoracic aorta. Operation was performed using left atrium-femoral artery bypass with centrifugal pump. The technique of graft interposition was selected rather than patch closure to prevent postoperative anastomotic aneurysm. We consider that in the treatment of inflammatory aneurysm, use healthy aortic wall for suture and end-to-end anastomosis are very important. In spite of steroid supplementation, the inflammatory reaction get worse postoperatively and the dosage of steroid had to be increased to control inflammation. The patient is well 20 months after surgery.

Aorta, Thoracic↗
PubMed1991

[Squamous cell carcinoma of the thymus].

A 68-year-old woman was admitted with cough and dyspnea. Her chest X-ray showed right pleural effusion and a mediastinal tumor. She underwent mediastinotomy following a preoperative diagnosis of invasive thymoma. A tumor originating from the thymus had invaded the right middle lobe and pericardium, and multiple pleural dissemination was also found. Therefore, considering the patient's age and pulmonary function, we performed only subtotal resection of the tumor. The pathological diagnosis was poorly differentiated squamous cell carcinoma. The patient received irradiation and chemotherapy including Cisplatin after surgery, but she died 1 year later because of rapid progression of distant metastases.

Aged↗
PubMed1990

Primate's p53 inhibits SV40 DNA replication in vitro.

Previous reports indicated that rodent p53 inhibits simian virus 40 (SV40) DNA replication in vitro as well as in vivo while that from primate cells does not (1-4). Here we report the evidence that p53 of primate origin also inhibits SV40 DNA replication in vitro. p53-SV40 large tumor antigen (T antigen) complex purified from SV40 infected COS-1 cells had little replication activity and inhibited SV40 DNA replication in vitro. These results suggest that inhibition of SV40 DNA replication by p53 should be regarded as general property of the protein and does not determine the mode of species specific replication of SV40 DNA.

Animals↗