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Biomedical subjects

K Iwatsuki

Publications and source records attributed to K Iwatsuki.

At least 217 records · Page 12Linked to original sources
PubMed1982

Water sorption-desorption test of the skin in vivo for functional assessment of the stratum corneum.

Based on the evidence from our previous studies that we can evaluate the hydration state of the skin surface quickly and quantitatively in terms of conductance to the high frequency electric current of 3.5 MHz, we have established a simple in vivo function test that furnishes information on the hygroscopic property and water-holding capacity of the stratum corneum in a few minutes. The test procedure consists of electromeasurements before and after application of a droplet of water on the skin for 10 seconds to obtain data on the hygroscopic property of the skin surface and later serial measurements at an interval of 30 seconds for 2 min to evaluate the water-holding capacity. Under usual ambient conditions normal skin surface showed a high rise in conductance just after application of water, which was followed by a rapid fall-off within 30 seconds, thereafter by gradual return to the prehydration levels by 2 min. By this method we have demonstrated that (i) the superficial horny layer of normal skin is much less hygroscopic and less capable of holding water than the corresponding deeper portions and that (ii) scaly skin shows functional defects in both hygroscopicity and water-holding capacity, between which the former normalizes much faster than the latter.

Absorption↗
PubMed1982

The speckled epidermal nuclear immunofluorescence of mixed connective tissue disease seems to develop as an in vitro phenomenon.

The pathogenesis of speckled epidermal nuclear immunofluorescence in patients with mixed connective tissue disease (MCTD) was studied by reproducing this reaction in guinea-pigs, using serum samples containing high titre antibody to ribonucleoprotein (RNP). Immunofluorescence studies on specimens obtained from guinea-pig skin into which serum samples containing high titre RNP antibody had been injected intradermally, revealed positive epidermal nuclear staining for IgG. This speckled immunofluorescence was demonstrable immediately after injection and remained so for 24 or 48 h. The pattern of fluorescence was similar in all cases, and there was no penetration of RNP antibody through the cell membrane. The epidermal nuclear fluorescence was not detected with sera at a dilution of 1:100 or more. These results provide strong evidence that the epidermal nuclear immunofluorescence observed in patients with high titre antibody to RNP develops as an in vitro phenomenon.

Animals↗
PubMed1982

Cardiac effects of YM-09538, a new alpha- and beta-adrenoceptor blocking agent, on SA nodal pacemaker activity and contractility in isolated atria and intact dogs.

The effects of a newly synthetic alpha- and beta-adrenoceptor blocking agent, YM-09538, on SA nodal pacemaker activity and contractility of atria and intact dogs were studied using isolated and blood-perfused canine atrial muscle preparations supported by a donor dog. Intravenous administration of YM-09538 (10-100 micrograms/Kg) caused hypotension without tachycardia, but was accompanied with bradycardia in anesthetized dogs. In these cases, the SA nodal pacemaker activity and atrial contractility in isolated atria was influenced little. This indicates that the concentration of YM-00538 that induces hypotension has no direct cardiac effects. Direct administration of YM-09538 to isolated atria caused dose-dependent negative chronotropic and inotropic effects, and the potency was 3-30 times less than that of propranolol. In electrically paced preparations, a large dose of YM-09538 produced a uniform depression of the developed tension at all frequencies examined (2-3 Hz). On the other hand, verapamil caused a greater suppression of developed tension at higher frequencies, indicating that the mode of action of YM-09538 is different from that of verapamil.

Adrenergic alpha-Antagonists↗
PubMed1982

Lymphadenoid structure induced by gold hypersensitivity.

An allergic sensitivity to gold earrings produced a lymphadenoid reaction with germinal centers in the dermis of the pierced earlobes of a 21-year-old woman, However, a patch test for 1% gold sodium thiomalate gave a long-lasting, clinically and histologically eczematous response. Electron microscopic and cytochemical observations showed that non-T lymphocytes and plasma cells were dominant in the dermal infiltrate of the lesions, whereas lymphocytes with convoluted nuclei (which were probably T cells) and monocytes invaded the epidermis in the patch test site. These findings suggest that continuous exposure of the dermis to gold in a sensitized person may induce a lymphadenoid cellular reaction different from the histologic findings seen after contact with the epidermis.

Adult↗
PubMed1982

Secretory and vascular responses to 1,1-dimethyl-4-phenylpiperazinium (DMPP) of the blood-perfused canine pancreas.

Effects of DMPP on the secretory and vascular responses were investigated in preparations of the isolated, blood-perfused canine pancreas. DMPP (10-300 micrograms) injected intra-arterially caused a dose-dependent increase in the secretion of pancreatic juice with a transient vasodilation followed by a long-lasting vasoconstriction. The secretory activity of 300 micrograms of DMPP was approximately equal to that of either 100 micrograms of acetylcholine or 0.07 units of secretin. DMPP-induced pancreatic secretion and vasodilation was completely inhibited by pretreatment with tetrodotoxin, hexamethonium, atropine and attenuated by haloperidol. DMPP-induced vasoconstriction was suppressed by tetrodotoxin, hexamethonium and phentolamine. DMPP increased protein concentration in the pancreatic juice. This action was similar to that of acetylcholine and different from that of secretin. From these results, it is suggested that the secretory and vascular responses to dMPP are due to the stimulation of both parasympathetic and sympathetic ganglia.

Acetylcholine↗
PubMed1981

Effects of nicardipine on the cross-perfused canine atrium.

Effects of nicardipine, a newly synthesized dihydropyridine vasodilator exhibiting cyclic phosphodiesterase inhibitory properties, were studied in the isolated canine atrium which was cross-perfused with blood from a donor dog. When nicardipine (1.0-10 micrograms/kg) was administered intravenously to the donor dogs, the systemic blood pressure decreased and the heart rate did not significantly change. However, the contraction and beat rate of the isolated atrium were only slightly decreased. At larger doses (30-100 micrograms/kg, i.v.), the systemic blood pressure fell markedly and was usually accompanied by marked bradycardia, which was greater than that of the isolated atrium. Nicardipine injected into the sinus node artery of the isolated atrium caused dose-related negative chronotropic and inotropic effects which were less pronounced than those of verapamil. In contrast, papaverine increased right atrial rate and contractile force. Nicardipine similarly to verapamil and unlike manganese ion caused greater inhibition of the right atrial contraction at higher than lower pacing frequencies. From these results, it is concluded that nicardipine may produce predominantly cardiac depressant properties as a calcium antagonistic, and that such may not be related to phosphodiesterase inhibition in cardiac tissues.

Anesthesia↗
PubMed1981

Effect of histamine on pancreatic exocrine secretion in the dog.

The effect of histamine on the secretion of pancreatic juice was investigated in preparations of isolated, blood-perfused dog pancreas. Histamine (3-30 microgram) injected intra-arterially caused dose-dependent increases in the secretion of pancreatic juice after a delay of a few minutes. 4-Methylhistamine (10-100 microgram), a selective histamine H2-receptor agonist, caused changes of the pancreatic secretion similar to those of histamine. Metiamide (100 microgram), a selective H2-receptor antagonist, blocked the increases of the pancreatic secretion in responses to both histamine or 4-methylhistamine. In contrast, diphenhydramine even at large doses (1 mg), a selective H1-receptor antagonist, did not effect histamine, or 4-methylhistamine-induced secretion. Histamine increased both bicarbonate and protein concentration in the juice. This action was different from that of secretion or pancreozymin. These results suggest that histamine increases pancreatic secretion acting directly on pancreatic cells through H2-receptors.

Animals↗