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Biomedical subjects

K Iwatsuki

Publications and source records attributed to K Iwatsuki.

At least 181 records · Page 10Linked to original sources
PubMed1986

Effects of diazepam on pancreatic exocrine secretion in the dog.

The effects of diazepam on pancreatic exocrine secretion were investigated in the vascularly isolated and self-hemoperfused dog pancreas under constant perfusion pressure of 100 mmHg. Close-arterial injections (i.a.) of diazepam (0.3-3.0 mg) caused dose-dependent increases in the secretion of pancreatic juice and in the rate of perfusion blood flow. Protein and bicarbonate concentrations of the pancreatic juice stimulated by 3.0 mg of diazepam were significantly higher than those of the resting pancreatic juice. The secretory activity of 1.0 mg (i.a.) of diazepam was comparable to that of 0.05 units (i.a.) of secretin. These secretory and vascular responses to diazepam were not modified by pretreatments with atropine, sulpiride, cimetidine, theophylline and Ro 15-1788. These results suggest that large doses of diazepam act directly on both acinar and ductular cells of the pancreas and induce protein and bicarbonate secretions.

Animals↗
PubMed1986

Blocking effects of verapamil on pancreatic exocrine secretion induced by dopamine in the dog.

The effects of verapamil on the dopamine-induced pancreatic exocrine secretion were investigated in the isolated and blood-perfused canine pancreas at a constant flow rate in situ. All drugs were given intra-arterially. Dose-related increases in the volume of pancreatic secretion induced by dopamine (1-10 micrograms) were reduced by infusion of 50 and 100 micrograms/min of verapamil, but were not affected by diltiazem (100 micrograms/min) and dilazep (100 micrograms/min) infusions. Protein concentration in pancreatic juice induced by dopamine was decreased significantly by the infusion of verapamil, diltiazem and dilazep, but bicarbonate concentration was not. These results suggest that verapamil reduced the dopamine-induced pancreatic secretion by virtue of its dopamine antagonist activity and inhibited protein secretion by virtue of its calcium channel blocking action.

Animals↗
PubMed1986

Effects of arterial pH and HCO-3 concentration on HCO-3 secretion in the isolated blood-perfused dog pancreas.

We examined the effects of plasma pH and plasma HCO-3 concentration on pancreatic HCO-3 secretion in resting state and in stimulated state by secretin, pancreozymin or dopamine, using the isolated blood-perfused dog pancreas. Secretin- or pancreozymin-induced HCO-3 secretion was sensitive to changes in both plasma pH and HCO-3 concentration. On the other hand, neither plasma pH nor plasma HCO-3 concentration affected dopamine-induced HCO-3 secretion and spontaneous HCO-3 secretion. These results suggest that secretin- or pancreozymin-induced pancreatic HCO-3 secretion is induced by the active H+-pump, but dopamine-induced or spontaneous pancreatic HCO-3 secretion may be caused by different mechanisms.

Animals↗
PubMed1985

Adenosine potentiates secretin-stimulated pancreatic exocrine secretion in the dog.

Pretreatment with graded doses of adenosine (0.1-1.0 mg), injected close-arterially (i.a.) to the vascularly isolated and self-hemoperfused dog pancreas, increased secretin (0.025 units i.a.)-stimulated secretory volume dose dependently and this effect of adenosine was reversed by further pretreatment with theophylline (0.3 mg i.a.). Adenosine itself did not affect the rate of resting secretion and the concentrations of protein and bicarbonate of the resting pancreatic juice. Adenosine decreased the concentration of protein and increased that of bicarbonate in the pancreatic juice stimulated by secretin. Adenosine, however, did not affect dopamine (3 micrograms i.a.)-stimulated pancreatic secretion. Adenosine (0.1-1.0 mg i.a.)-induced vasodilation was also reversed by the pretreatment with theophylline (0.3 mg i.a.). These results suggest the existence of adenosine 'R' receptors in the exocrine cells and the vasculature of the dog pancreas.

Adenosine↗
PubMed1985

Primary tissue culture of spontaneously regressing flat warts. In vitro attack by mononuclear cells against wart-derived epidermal cells.

Although tumors may be resolved due to host immune response, it is difficult to obtain direct evidence of this in man. Numerous flat warts, human papilloma virus type 3-induced papillomas, disappear systemically and simultaneously after showing inflammatory changes. Histologically, there is a dense cellular infiltration composed of lymphocytes and mononuclear phagocytes as identified by alpha-naphthyl acetate esterase staining in situ, the former being predominant in most cases. The primary tissue culture of such inflamed flat warts from ten cases revealed a proliferation of wart-derived keratinocytes as is the case with ordinary flat warts. However, in nine of the ten cases, massive mononuclear cells, most of which were T-lymphocytes, migrated out of the explants and began to attack these keratinocytes, inducing degenerative changes. These findings indicate that cell-mediated tumor cell destruction rather than antiviral reaction induces systemic spontaneous regression of multiple papillomas in man.

Adolescent↗
PubMed1985

Deuterium oxide (D2O) enhances the photosensitivity of Stentor coeruleus.

Stentor coeruleus exhibits negative phototaxis and step-up photophobic response (avoiding reaction) to visible light (maximum at 610-620 nm in both responses). In the presence of deuterium oxide (D2O) the step-up photophobic response was markedly enhanced, whereas the phototactic orientation response was inhibited. The induction time for the step-up photophobic response was longer in D2O than in H2O, and the duration of ciliary reversal for the response was also longer in D2O than in H2O, indicating that certain steps of the sensory transduction chain are subject to solvent deuterium isotope effects. The enhancement of the step-up photophobic response in D2O was canceled by LaCl3, while the inhibition of the phototactic orientation response in D2O was partially removed by LaCl3, even though LaCl3 did not affect the phototactic orientation response. These results suggest that the sensory transduction mechanisms for the two photoresponses are different, although the photoreceptors (stentorin) are the same.

Animals↗
PubMed1985

Identification of Ten Gibberellins from Sporophytes of the Tree fern, Cyathea australis.

Ten gibberellins (GAs) have been identified by Kovats retention indices and full mass spectra from GC-MS analysis of purified extracts of sporophytes of the tree-fern, Cyathea australis. These include the known GA(1), GA(4), GA(9), GA(15), GA(24), GA(35), and GA(58) and three new GAs, 12beta-hydroxyGA(9) (GA(69)), 12alpha-hydroxyGA(9) (GA(70)) and 12beta-hydroxyGA(4) (GA(71)). The structure of GA(71) was established by the preparation and characterization of its methyl ester (as a metabolite of GA(4) methyl ester in a culture of prothallia of Lygodium japonicum).

Journal Article↗
PubMed1985

The Langerhans cell granule is an adsorptive endocytic organelle.

The role of Langerhans cell granules (LCG) in adsorptive endocytosis was studied by using concanavalin A (Con A) and heterologous anti-epidermal cell serum (AES) as ligands. Isolated epidermal cells were obtained by trypsinization of guinea pig skin fragments and exposed to ferritin-conjugated Con A or AES followed by ferritin-conjugated second antibody at 37 degrees C for various times up to 30 min. Langerhans cells among the treated epidermal cells were observed by electron microscopy. Shortly after the incubation, a few LCG in the cell periphery were filled with ferritin particles in the bulb portion. After prolonged incubation, ferritin-containing LCG increased in number and seemed to move to the juxtanuclear area. The granules were derived from plasma membrane invaginations that collected ferritin particles in a saclike extension at the end. Some of these invaginations were apparently of coated pit origin. The contents in the bulb of LCG seemed to be delivered finally to intracellular degradation compartments. Our findings clearly demonstrate that LCG are an adsorptive endocytic organelle.

Adsorption↗
PubMed1985

Alterations of surface receptors on intralesional neutrophils in pustular psoriasis and palmo-plantar pustulosis.

Alterations of binding capacity of surface IgG-Fc and complement receptors were demonstrated in polymorphonuclear neutrophils (PMNs) obtained from the pustular lesions of psoriasis. A marked decrease of C3 receptors, but not of IgG-Fc, was found in PMNs from the lesions of palmo-plantar pustulosis (PPP) and bacterial pustules. PMNs from pustular lesions of psoriasis exhibited only a slight decrease in the number of C3 receptors. No significant decrease in membrane receptors was noted in circulating PMNs from psoriatic patients. We suggest that mechanisms of formation of aseptic subcorneal pustules, mediated by PMN membrane receptors for C3 fragments, are different in pustular psoriasis and PPP.

Bacterial Infections↗
PubMed1985

Contribution of prostaglandins to dopamine actions in the pancreas of anesthetized dogs.

We investigated the effect of dopamine and arachidonic acid on pancreatic blood flow and exocrine secretion in the isolated blood-perfused pancreas of pentobarbital sodium-anesthetized dogs without or with pretreatment with indomethacin or sodium meclofenamate in the absence and during infusion of prostaglandins I2 or E2 (PGI2 or PGE2). Intra-arterial administration of dopamine (50-500 ng/kg) produced an initial vasoconstriction followed by vasodilation and enhanced flow rate of pancreatic exocrine secretion. Arachidonic acid (0.5-5 micrograms/kg) produced vasodilation without altering the flow rate of pancreatic exocrine secretion. In animals pretreated with indomethacin or sodium meclofenamate (10 mg/kg iv), the magnitude and the duration of the biphasic vascular response but not the increase in flow rate of pancreatic exocrine secretion elicited by dopamine were reduced. Arachidonic acid-induced vasodilation was abolished by the cyclooxygenase inhibitors. During infusion of PGI2 or PGE2 (10 ng X kg-1 X min-1 ia), the inhibitory effect of indomethacin or sodium meclofenamate on the vasodilator phase of the response to dopamine was diminished. These data suggest that prostaglandins, presumably PGI2 and PGE2, contribute to the effect of dopamine to increase pancreatic blood flow but not to increase pancreatic exocrine secretion in anesthetized dogs.

Animals↗
PubMed1985

Effects of synthesized phosphodiesterase inhibitors, DM 9278 and HWA 285, on pancreatic exocrine secretion of the dog.

The effects of synthesized phosphodiesterase inhibitors, DM 9278 and HWA 285, on pancreatic exocrine secretion were investigated in isolated and blood-perfused canine pancreas. Close-arterial injections of DM 9278 (10-300 micrograms) and HWA 285 (300-3000 micrograms) caused dose-dependent increases in the flow rate of pancreatic juice and perfusion blood flow. Bicarbonate concentration in the pancreatic juice stimulated by DM 9278 (300 micrograms) or HWA 285 (3000 micrograms) was significantly higher than that in the resting pancreatic juice, although neither of the compounds affected protein concentrations in the pancreatic juice. In the secretory volume, 100 micrograms of DM 9278 corresponded roughly to 1000 micrograms of HWA 285, 0.1 units of secretin or 0.3 units of pancreozymin. These secretory and vascular effects were not modified by pretreatment with atropine or sulpiride. This study suggests that both DM 9278 and HWA 285 act directly on ductular cells of the pancreas and induce secretion of water and electrolytes.

Animals↗
PubMed1985

Permissive role of prostaglandins in the action of bradykinin on the pancreas of anesthetized dogs.

We have investigated the contribution of prostaglandins (PGs) to the effect of bradykinin on pancreatic blood flow and pancreatic exocrine secretion by examining its actions in the isolated blood-perfused pancreas of pentobarbital-anesthetized dogs. Intra-arterial injections of bradykinin (0.05-5 ng/kg) into the pancreas produced a dose-dependent vasodilation and increased pancreatic blood flow; the rate of flow, bicarbonate concentration, protein content or pH of the pancreatic juice was not altered. Administration of arachidonic acid (0.5-5 micrograms/kg) into the pancreas also produced vasodilation without altering pancreatic exocrine secretion. In animals pretreated with indomethacin or sodium meclofenamate (10 mg/kg i.v.), the vasodilator effect of bradykinin was attenuated, whereas that of arachidonic acid was abolished; the pancreatic exocrine secretion was not altered. The vasodilation produced by sodium nitroprusside (0.3 micrograms/kg i.a.) in the pancreas was not altered by indomethacin. During infusion of PGI2 or PGE2 (10 ng/kg/min i.a.), the effect of indomethacin or sodium meclofenamate to attentuate bradykinin-induced vasodilation was reduced. However, the sodium nitroprusside-induced vasodilation in animals treated with indomethacin was not altered during infusion of PGI2 or PGE2. These data indicate that PGs, presumably PGI2 and PGE2, play a permissive role in the vasodilator effect of bradykinin in the pancreas of anesthetized dogs. Moreover, these studies suggest that neither bradykinin nor PGs contribute to the regulation of pancreatic exocrine secretion.

Animals↗
PubMed1985

Effects of thyrotropin-releasing hormone on pancreatic exocrine secretion in the dog.

Effects of thyrotropin-releasing hormone (TRH) on pancreatic exocrine secretion were investigated in isolated and blood-perfused canine pancreas preparations. During constant intra-arterial infusion of secretin (0.03-0.05 units/min), concentrations of protein and bicarbonate in the pancreatic juice were measured before and after intra-arterial injection of TRH (0.1-10 ng). TRH did not produce any significant changes in the flow rate of pancreatic juice and in the rate of pancreatic blood flow. TRH caused a significant suppression of protein and bicarbonate output in a dose-dependent manner. At 10 ng of TRH, this suppression lasted about 20 min. From these data, it is suggested that TRH acts directly on both acinar and ductular cells of the pancreas and inhibits the secretions of digestive enzymes and bicarbonate.

Animals↗
PubMed1985

Effects of isosorbide dinitrate on pancreatic exocrine secretion in the dog.

The effects of isosorbide dinitrate (ISDN) on pancreatic exocrine secretion were investigated after intravenous administration in the whole animal and after close-arterial administration on the isolated and blood-perfused dog pancreas preparations. ISDN (10-100 micrograms/kg), injected into the femoral vein, caused a dose-dependent increase in flow rate of pancreatic juice and in protein concentration of the pancreatic juice. Close-arterial injections of ISDN (100-1000 micrograms) produced a dose-dependent increase in perfusion blood flow, flow rate of pancreatic juice and protein concentration of the pancreatic juice without affecting its bicarbonate concentration. These vascular and secretory effects were not modified by pretreatment with atropine. From these data, it is suggested that ISDN induces pancreatic enzyme secretion by acting directly on the acinar cells of the pancreas.

Animals↗
PubMed1984

Mechanisms of pustule formation in cutaneous bacterial and viral infections: alterations of neutrophil membrane surface receptors.

Changes in membrane surface receptors have been demonstrated by rosetting methods in polymorphonuclear leukocytes obtained from the pustules of different infectious dermatoses. There was a distinct difference in numbers of receptors in neutrophils from bacterial and viral pustules, i.e., C3b receptors were decreased on neutrophils from both bacterial and viral pustules, whereas IgG-Fc receptors were decreased only in neutrophils from viral pustules. The difference appears to be due to variations in the defence mechanisms against the invading micro-organisms.

Acne Vulgaris↗