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Biomedical subjects

I Amano

Publications and source records attributed to I Amano.

At least 19 recordsLinked to original sources
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↗
PubMedDate not supplied

Development of alumina ceramic transcutaneous connector to prevent skin exit site infections around CAPD catheters.

It is very important to prevent skin exit site infections in order to continue continuous ambulatory peritoneal dialysis (CAPD) safely over the long-term. The silicon material conventionally used can result in sinus formation between the skin and the catheter, and may trigger exit site infections. To resolve this problem, we employed a bioinert, rigid, and nonporous transcutaneous connector made of alumina ceramic. Earlier long-term animal experiments with alumina ceramic placed in soft tissue demonstrated the outstanding biocompatibility of this material. The transcutaneous connector was designed with a simple cylindrical configuration; in order to make sufficient contact between this connector and the patient, a silicon tube was made into a swan neck catheter with a disk-shaped Dacron cuff at the upper position in order to reinforce adhesion to soft tissue. Ten CAPD patients (maximum time on dialysis of 14 months) have used the new CAPD catheter system with no exit site infections to date. Furthermore, there has been virtually no downgrowth of the skin around the connector, while the connector and tissue have remained in very close contact.

Aluminum↗