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Biomedical subjects

K Iwamoto

Publications and source records attributed to K Iwamoto.

At least 181 records · Page 10Linked to original sources
PubMed1988

A new bleeding tendency due to hereditary hyper alpha 2-macroglobulinemia.

A heritable elevation in alpha 2-macroglobulin (alpha 2M) was identified in a 9-year-old girl with a severe bleeding tendency and activated partial thromboplastin time (APTT) prolonged to 49.1 sec (normal 27-38) as well as recalcification time prolonged to 438 sec (less than 180). The addition of her plasma to normal plasma made APTT prolong from 26.8 to 38.3 sec. The plasma alpha 2M levels in her relatives were checked, i.e., proband, her sister, mother, maternal grandmother, father, and paternal grandmother: Their levels were 406, 380, 352, 339, 166 and 236 mg/100 ml (140-285), respectively. Thus the patient's condition was thought to be an autosomal dominant disease, though her other relatives displayed no apparent clinical symptoms. Of significance was that a possible causal association between her elevated alpha 2M and her prolonged APTT was indicated. The activity of the alpha 2M, determined as trypsin-protein esterase, was 351 mg/100 ml (197%). The alpha 2M also demonstrated normal horizontal mobility to anti-alpha 2M plasma with a high precipitin arc (showing the difference of the protein concentration) by crossed immunoelectrophoresis, and a normal horizontal mobility of immunofixation electrophoresis. In addition, after analysis of testing done by SDS-polyacrylamide-gel-electrophoresis, we found no qualitative abnormality in the alpha 2M of the patient.

Blood Coagulation Disorders↗
PubMed1988

Evaluation of lopamidol and diatrizoate in excretory urography: a double-blind clinical study.

Image opacification, patients' tolerance, and clinical and laboratory findings were evaluated in patients having excretory urography at three centers. In a double-blind, parallel study, iopamidol was compared with diatrizoate (50-ml dose), and in an open-label trial, the administration of a 100-ml dose of iopamidol was evaluated. In the double-blind study, a total of 84 patients received 50 ml of either iopamidol or diatrizoate. In the open-label study, another 42 patients received a 100-ml dose of iopamidol. Image opacification scores after the administration of the 50-ml doses showed better opacification with iopamidol than with diatrizoate in the renal calices (p less than .05) and in the composite kidney (p less than .05). Opacification scores were higher for 100-ml doses of iopamidol than for 50-ml doses in all anatomic regions as well as in the composite kidney (p = .0001). Patients' tolerance to iopamidol was significantly better than their tolerance to diatrizoate (p less than .025). Investigators observed adverse drug reactions in a total of 10 patients. In the double-blind study, one of 43 patients had transient bradycardia after the administration of iopamidol. In the same study, four of 41 patients who received diatrizoate had five minor adverse drug reactions. With 100-ml doses of iopamidol, five of 42 patients had adverse reactions. No adverse side effects required therapy in either study. There were no significant changes in vital signs or laboratory values after drug administration. The results of this study show that iopamidol is a suitable agent for excretory urography at doses of 50 and 100 ml. Patients report fewer unpleasant side effects with iopamidol than with diatrizoate. Overall image quality was better with iopamidol than with diatrizoate. Overall evaluation of drug performance was better with iopamidol than with diatrizoate.

Adolescent↗
PubMed1987

Age dependence in capacity-limited jejunal decarboxylation of levodopa in rats.

The extent of levodopa decarboxylation in a jejunal preparation permitting continuous in situ collection of the mesenteric blood was compared in rats 5 to 104 weeks old. The fraction of the absorbed amount that was metabolized (decarboxylated) in the jejunal segment was relatively high (approximately 0.7 to 0.8) in 9- to 15-week-old rats, whereas the fraction in relatively aged (52- and 104-week-old) and young (5- and 7-week-old) rats was considerably less (approximately 0.4 or less). These fractions were found to correlate better with the extent of relative contribution of the intestine in producing the overall first-pass effect of this drug after oral administration. In addition, kinetic studies on the jejunal metabolism of levodopa in vitro showed that a capacity-limited (i.e. saturable) decarboxylation rate was highest in 11-week-old rats. Therefore, the capacity-limited decarboxylation rate in the small intestine may be a determining factor in the age-dependent systemic availability of this drug when administered orally.

Aging↗
PubMed1987

Origin of the initial negative potential (N15) recorded on the skull by superficial radial nerve stimulation in the cat.

The origin of the initial prominent negative potential with a latency of about 15 msec (N15), recorded on the skull by superficial radial nerve stimulation was studied in the cat, and the following results were obtained. In the direct recording from the cortex, SEPs were elicited from the SI and SII areas, as well as the lateral gyrus and anterior suprasylvian gyrus. Among various wave forms recognized in the SI area, diphasic positive-negative (P-N) potential obtained from the postero-lateral part was most distinct, representing the primary evoked potential. Responses recorded on the dura and those directly on the cortex showed similar wave patterns over many sites. Although different forms of evoked potentials were recorded extensively over the skull, the most prominent negative potential was elicited at the site corresponding to the postero-lateral part of the SI area. The latency of this potential was approximately in agreement with that of the negative component of the P-N potential recorded on the cortex. Based on the intracortical laminar analysis of P-N potential, the positive component of this potential was assumed to reflect the activity of cells in the deeper layer of the cortex. The negative component, on the other hand, might represent activities of apical dendrites of the cortex. From the result of functional elimination of the cortex, however, this positive component was thought to contain potentials from far field neural structures. N15 recorded on the skull completely disappeared during cortical spreading depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1987

Origin of short latency somatosensory evoked potential in cats: especially potentials derived from thalamus and cortex.

Short latency somatosensory evoked potential (SSEP) was recorded in cats to identify the potentials originating from the cortex and the thalamus, and the following results were obtained. When SSEP was elicited on the bregma by stimulation of the contralateral superficial radial nerve, P2, P4, P4.5, P5.5, P7, P8, N8.5, P11, P9.5, N11.5, N12.5 and N14 were recognized. Of these components N11.5, N12.5 and N14 consisted of large negative potential (LNP). When KCl was applied to the sensorimotor cortex to induce spreading depression, the positive component of the primary evoked potential was markedly decreased and the negative component disappeared. In SSEP, components preceding N8.5 were unchanged. N8.5-P11 and P11-N12.5, however, markedly diminished or disappeared. The latency of the first component of the field potential recorded in the VPL nucleus of the thalamus was about 5 ms. When a small amount of Nembutal was injected into VPL nucleus, components between P2 and P4.5 remained unchanged, but P5.5 disappeared. P7, P8 and N8.5 were preserved. The amplitude of N8.5-P11 was markedly decreased and LNP disappeared. From these results, among various components of SSEP, P5.5 should originate from the thalamus, and P7, P8 and N8.5 from the extralemniscal system. N8.5-P11 should mainly represent post-synaptic potential (PSP) in the deep somatic layer, and P11-N12.5 represent PSP in the apical dentrites of the sensorimotor cortex. N14 probably represents PSP via the diffuse projection system. Thus, LNP should consist of complex potentials of specific and non-specific sensory systems.

Animals↗
PubMed1987

Mandibular and parotid salivary excretion of procainamide and N-acetylprocainamide after intravenous administration of procainamide to rats.

Flow rate, protein level and pH of mandibular and parotid saliva samples in rats were almost stabilized 2 h after induction of salivation with pilocarpine (9.0 mg h-1 kg-1). Salivary excretion profiles of procainamide, 50 mg kg-1 i.v., and its metabolite N-acetylprocainamide (NAPA) were then investigated. Plasma and salivary procainamide levels declined bi-exponentially with time almost in parallel. Salivary procainamide levels (Y) from both types of gland were correlated with the plasma level (X) over a wide concentration range [Y = 0.108X + 1.96 (r = 0.795) for mandibular and Y = 0.917X (r = 0.974) for parotid glands]. The mean saliva to plasma concentration ratio (S/P ratio) was significantly higher in parotid (0.974 +/- 0.243) than in mandibular (0.284 +/- 0.119) saliva samples. Similar correlations and S/P ratios were observed for NAPA. Procainamide and NAPA mean S/P ratios for saliva from both glands were fairly consistent with the calculated value according to the pH-partition hypothesis.

Acecainide↗
PubMed1987

High capacity for pulmonary first-pass elimination of propranolol in rats.

Plasma propranolol concentrations after i.v. and i.a. 1, 2.5, 5 and 10 mg kg-1 doses of the drug given intravenously or intra-arterially have been compared in 7-week-old male Wistar rats. The areas under the curves after i.a. dosing were almost twice those after i.v. dosing at any dose, despite the elimination half-lives being the same. The difference in total body clearance after i.a. dosing from that after i.v. dosing indicated a significant contribution by pulmonary clearance, which ranged from about 20 to 30 mL min-1 kg-1, to the overall first-pass elimination after the i.v. administration. The pulmonary extraction ratio was approximately 0.4 to 0.5 at the i.v. doses used. Mean pulmonary transit time was estimated to be about 1 to 2 min. There was no dose-dependence in the pulmonary first-pass elimination kinetics of propranolol.

Animals↗
PubMed1987

Effect of age on gastrointestinal and hepatic first-pass effects of levodopa in rats.

Presystemic elimination of levodopa (20 mg kg-1) has been studied in 5- to 104-week-old male Wistar rats. The gastrointestinal and hepatic contribution to the overall first-pass effect was estimated separately after the drug had been administered intravenously, orally and intraportally. The contribution of the gut to the overall first-pass effect of this drug was greater than that of the liver in any age-group of the rats. Both the overall and intestinal first-pass effects of levodopa were greatest in 11-week-old rats and relatively small in both young (between weeks 5 and 7) and aged (between weeks 52 and 104) rats. In contrast, the hepatic first-pass effect did not show any significant age-dependent change. Age-related change in the jejunal blood flow could not explain the unique age-dependence in the intestinal first-pass metabolism of levodopa. However, the present age-dependence in the oral systemic availability of this drug between adult (11 weeks) and aged (52 to 104 weeks) rats was found to be similar to the tendency that has been reported between normal adult subjects and aged patients with Parkinson's disease.

Administration, Oral↗