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Biomedical subjects

I Amano

Publications and source records attributed to I Amano.

At least 37 records · Page 2Linked to original sources
PubMed1994

Dephosphorylation of nuclear non-histone proteins in submandibular glands of rats treated with isoproterenol.

Protein phosphatase that removed [32P]phosphate from non-histone proteins, i.e., phenol-soluble acidic proteins, more rapidly and strongly than from histone proteins was present in nuclei of rat submandibular glands, but was not associated with chromatin. Cyclic AMP (10(-4)-10(-2) mM) stimulated the dephosphorylation of non-histone proteins, but not that of histone proteins. After a single injection of isoproterenol (IPR), the dephosphorylation of non-histone proteins in rat submandibular gland nuclei increased within 15 min, reached a maximum in 30 min and returned to normal control levels within 4 h. The stimulation of dephosphorylation of non-histone proteins induced by IPR was not observed after prior treatment of the animals with dichloroisoproterenol. The dephosphorylation of histone proteins was not affected by the injection of IPR. Stimulation of beta-adrenoceptors with IPR in rat submandibular glands resulted in increase in cyclic AMP and decrease in RNA synthesis in the tissues in the first few hours after the injection. This decrease in RNA synthesis was temporary and was preceded by the increase in cyclic AMP level and in the dephosphorylation of non-histone acidic proteins in the tissues. These results suggest that protein phosphatase in nuclei plays an important part in the events controlling RNA synthesis by regulating the state of phosphorylation of non-histone acidic proteins. In addition, the phosphatase may be regulated by a function of the cytoplasmic membranes.

Animals↗
PubMed1993

Age-dependent changes in the phosphorylation of nuclear proteins of submandibular glands in isoproterenol-treated rats.

Age-dependent changes in the regulation of the phosphorylation of nuclear proteins were investigated in relation to DNA synthesis in rat submandibular glands after injection of isoproterenol (IPR). The level of phosphorylation of nuclear proteins in the tissue increased rapidly after birth, reaching a maximum at 4 weeks, and then decreased to the level of 52-week-old rats. The level of protein kinase activity in nuclei varied in parallel with that of phosphorylation of nuclear non-histone proteins after birth. The time after the injection of IPR required to initiate the phosphorylation of nuclear non-histone proteins of rat submandibular glands, which occurs prior to the onset of RNA synthesis that precedes the replication of DNA, increased with age. These results suggest that this delayed onset of phosphorylation plays a regulatory role in cell proliferation and cell function during aging.

Aging↗
PubMed1993

[Accumulation of a disopyramide metabolite in renal failure].

Twenty-nine cases of hypoglycemia induced by disopyramide (DP) have been reported in the literature to date. Twenty of the reported cases showed hypo-renal function and a high concentration was rare. DP is metabolized to mono-N-dealkyldisopyramide (MND) in the liver and accumulation of MND is to be expected in renal failure. Both DP and MND bind mainly to alpha-1-acid glycoprotein (AAG) in the plasma. In 10 hemodialysis (HD) patients with normal liver function receiving DP therapy in the steady state. DP, MND and AAG were measured pre- and post-HD. Ten patients with normal renal and liver function were selected as the controls. The DP concentration was 2.08 +/- 0.39 micrograms/ml (mean +/- SD) in the control group, and the pre- and post-HD levels were 2.40 +/- 1.08 micrograms/ml and 1.73 +/- 0.87 micrograms/ml, respectively, in the HD group. The MND concentration was 0.42 +/- 0.23 micrograms/ml in the controls, 1.53 +/- 0.52 micrograms/ml in pre-HD and 1.08 +/- 0.32 micrograms/ml in post-HD. Although DP and MND are both classified as substances of small molecular weight, the average decrease in plasma concentration from pre- to post-HD was under 30% with both agents. The MND/DP ratio in the HD group was higher than in the controls, but there was no significant difference between pre- and post-HD. The AAG level was 75 +/- 5mg/dl in the controls and 109 +/- 11mg/dl before HD in the HD group (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Diurnal variation of amylase secretion is coupled with alterations of beta-adrenoceptors in the rat parotid gland.

Diurnal changes in the neurotransmitter receptors are important for studying the receptor function in neurophysiology. The purpose of this study is to gain an insight into the regulatory mechanisms of the diurnal variation of amylase secretion. Rat salivary amylase levels showed a diurnal variation with two peaks, a marked peak at 13 h and a lesser peak at 21 h. This increase in salivary amylase levels was completely inhibited by pretreatment of rats with the beta-adrenergic antagonist propranolol, but not by the alpha-adrenergic antagonist phentolamine. Amylase level in parotid tissue homogenate also showed a diurnal change, but there was only one peak, at 13 h. The number of maximal binding sites (Bmax) for [3H]dihydroalprenolol (DHA) in parotid membranes showed a diurnal variation with two marked peaks at 13 and 21 h, but the affinity of parotid beta-adrenoceptors for agonists or antagonists did not show any diurnal changes. Phosphorylation of nuclear non-histone proteins in the rat parotid gland showed diurnal variation with two marked peaks at 13 and 21 h. These results indicate that a diurnal variation in the number of rat parotid beta-adrenoceptors, which is presumably regulated by gene expression, is coupled with a change in salivary amylase secretion.

Amylases↗
PubMed1991

Clinical effect of continuous gastric cooling for massive GI bleeding in uremia.

Continuous gastric cooling (CGC) with dialysate was done in nine hemodiaysis patients with massive gastro-intestinal (GI) bleeding. Eight patients were treated by direct irrigation using a double-lumen naso-gastric (NG) tube without balloon. Four patients with bleeding from the duodenum (B-f-D) had complete hemostasis, and there was only one recurrence. However, two out of four patients with bleeding from the stomach (B-f-S) had complete hemostasis, but all four suffered recurrence. The NG tube had to be reinserted in three patients with B-f-S because of obstruction by clots. The direct irrigation method of CGC thus appears to be more effective for the treatment of B-f-D than B-f-S, so we investigated a three lumen, single-balloon catheter (3L-SBC) with which the bleeding site in the stomach can be cooled and pressed without removing coagula. CGC using the 3L-SBC was done in one patient with B-f-S, and complete hemostasis was obtained without recurrence.

Adult↗
PubMed1990

Desensitization of mucin secretion from rat submandibular tissues in response to isoproterenol.

Studies on the secretory response of rat submandibular tissues to isoproterenol (IPR) and the neurotransmitter receptors show that beta-adrenoceptors are altered with specific changes in mucin secretion by brief treatment of the tissues with IPR. Mucin secretion is stimulated by IPR in a dose dependent manner. Pretreatment with 10 microM of IPR for 10, 15, or 30 min reduces mucin secretion during further incubation with the same amount of IPR and increases the EC50 values of mucin secretion for IPR. A binding experiment of [3H] dihydroalprenolol (DHA) shows that this pretreatment also reduces the Bmax of beta-adrenoceptors from 162 +/- 2 to 140 +/- 1 fmol/mg protein and increases the IC50 values of IPR from 195 +/- 17 to 685 +/- 73 nM. The alteration in beta-adrenoceptors by brief treatment of IPR is paralleled by a change in the cyclic AMP content in the tissues from 143.2 +/- 3.2 to 102.3 +/- 4.6 pmol/mg protein.

Adenylyl Cyclases↗
PubMed1990

Clinical experience with alumina ceramic transcutaneous connector to prevent skin-exit infection around CAPD catheter.

To prevent skin-exit infection, an important CAPD complication, we developed a transcutaneous connector made of Alumina ceramic. The new connector could be downsized, because an Alumina ceramic is characteristically bio-inert, rigid and non-porous. Our animal experiments with Alumina ceramic in soft tissue demonstrated the outstanding bio-compatibility of this material. The shape of the new transcutaneous connector was of simple cylindrical configuration so as to inhibit macrostress beneath the skin. To make contact with this connector in the body, a silicon tube was made into a Swan-necked catheter with a disk-shaped polyester cuff, which was positioned subcutaneously beneath the transcutaneous connector in order to reinforce adhesion to soft tissue. The silicon tube itself was L-shaped in its outside portion just before reaching the connector. We are now using this new transcutaneous connector made of Alumina ceramic on a CAPD catheter in 8 patients. In the longest case of a patient using it, there has been no skin-exit infection for 12 months. Also, there has been virtually no downgrowth phenomenon in the skin around the connector, and the connector and tissue have remained in very close contact, although fibrous connective tissue has been seen to form in the area.

Aluminum Oxide↗
PubMed1989

Peritoneal dialysis as therapy for electrolyte and acid base disorders.

Peritoneal dialysis (PD) does not demand special equipment and its fluid composition can be easily changed according to the individual condition. Nine patients with chronic or acute renal failure presented severe metabolic alkalosis (MA). Hemodialysis (HD) proved virtually ineffective and the MA persisted. Physiological saline solution was adopted as the main component of the PD fluid for the treatment of MA. By this method, Cl- can be shifted from PD fluid to extracellular fluid (ECF) and HCO3- from ECF to PD fluid by ionic gradient. Therefore, pH and base excess (BE) of these patients both improved to the normal range after several fluid exchanges. The lowering effect of BE (delta BE/L) ranged from 0.99 to 2.6. Hyposaline and normo-osmol solution (Na+ 70 mEq/L) were used for one patient with hypernatremia and consciousness disturbance. Serum (S)-Na decreased from 170 to 138 mEq/L, and consciousness became almost clear with the use of 15 L of PD fluid. Hypersaline solution (Na+ 190 mEq/L) was used for two patients with hyponatremia (S-Na 113 and 121 mEq/L). S-Na rose to within the normal range after 16 and 9 L in the two cases. A fluid mixed with distilled water, 10% NaCl and 7% NaHCO3 (HCO3 34-68 mEq/L) was used to treat lactic acidosis in two patients. By this method, HCO3- can be shifted from PD fluid to ECF and lactic acid from ECF to PD fluid. Two patients recovered from prolonged shock, and pH was corrected by 10 L and 4 L, respectively. PD should be considered for application in other diseases besides renal failure.

Acid-Base Imbalance↗
PubMed1986

An ovulation inducing agent containing clomiphene citrate causes DNA-strand breaks without SOS responses in Escherichia coli.

Effects of Clomid, an ovulation-inducing drug containing clomiphene citrate, on Escherichia coli were investigated. Radiation-sensitive mutants, uvrA and recA, were more sensitive to Clomid than the parental wild-type strain. DNA synthesis in these two strains was more depressed by Clomid than that in the wild-type strain. Clomid caused DNA-strand breaks, but few SOS responses such as mutation, induction of prophage and expression of the umuC+ gene were induced.

Clomiphene↗