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T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 937 records · Page 52Linked to original sources
PubMed1988

Insulin-degrading enzyme is capable of degrading receptor-bound insulin.

In the investigation of the intracellular sites of insulin degradation, it might be important whether receptor-bound insulin could be a substrate for insulin-degrading enzyme (IDE). Insulin receptor and IDE were purified from rat liver using a wheat germ agglutinin column and monoclonal anti-IDE antibody affinity column, respectively. [125I]insulin-receptor complex was incubated with various amounts of IDE at 0 degree C in the presence of disuccinimidyl suberate and analyzed by reduced 7.5% SDS-PAGE and autoradiography. With increasing amounts of IDE, the radioactivity of 135 kd band (insulin receptor alpha-subunit) decreased, whereas that of 110 kd band (IDE) appeared then gradually increased, suggesting that IDE could bind to receptor-bound insulin. During incubation of insulin-receptor complex with IDE at 37 degrees C, about half of the [125I]insulin was dissociated from the complex. However, the time course of [125I]insulin degradation in this incubation was essentially identical to that of free [125I]insulin degradation. Cross-linked, non-dissociable receptor-bound [125I]insulin was also degraded by IDE. Rebinding studies to IM-9 cells showed that the receptor binding activity of dissociated [125I]insulin from insulin-receptor complex incubated with IDE was significantly (p less than 0.001) decreased as compared with that without the enzyme. These results, therefore, show that IDE could recognize and degrade receptor-bound insulin, and suggest that IDE may be involved in insulin metabolism during receptor-mediated endocytosis through the degradation of receptor-bound insulin in early neutral vesicles before their internal pH is acidified.

Animals↗
PubMed1988

Wyburn-Mason syndrome: report of a rare case with computed tomography and angiographic evaluations.

A case of Wyburn-Mason syndrome comprising unilateral retinocephalic vascular malformations is reported in a 7-year-old girl presenting with proptosis of the left eye associated with injection of the bulbar conjunctiva. This rare congenital vascular disorder is reviewed in the literature, and in particular the neuroradiological findings are detailed in the presented case.

Cerebral Angiography↗
PubMed1988

Expression of rat alpha-fetoprotein cDNA in Escherichia coli and in yeast.

Rat alpha-fetoprotein (AFP) cDNA spanning the complete coding region was cloned and expressed in Escherichia coli as well as in yeast, Saccharomyces cerevisiae. The recombinant AFPs (rAFPs) were purified and characterized. The molecular weights determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis were 65,000 for E. coli rAFP and 69,000 for yeast rAFP. Amino acid and N-terminal sequence analyses indicated that yeast cells produced mature AFP by processing the signal peptide properly but E. coli rAFP lacked the N-terminal 53 amino acid residues of preAFP. The yeast rAFP was found to be indistinguishable from authentic AFP in the Ouchterlony immunodiffusion test, radioimmunoassay and estradiol-binding assay while E. coli rAFP was less reactive in these tests. These observations indicated that the rAFP expressed in yeast emulated the properties of authentic AFP.

Amino Acid Sequence↗
PubMed1988

A theoretical study of the dielectric constant of protein.

The dielectric properties of a protein molecule were investigated by calculating a 'local dielectric constant' with the aid of normal mode analysis. This local dielectric constant was calculated from the electronic polarization of atoms and the orientational polarization of local dipoles. The former was obtained from atomic polarizations of the whole atoms in a protein molecule. The latter was determined from the fluctuation-dissipation theorem. The degree of dipole fluctuation was calculated from the positional fluctuation of each atom obtained by the normal mode analysis. Assuming a minimum volume for a continuum model, the resulting local dielectric constants ranged from 1 to 20 inside the protein.

Electric Conductivity↗
PubMed1988

The effect of ouabain on pressor responses to infused noradrenaline in patients with essential hypertension.

The relationship between changes in the pressor response to infused noradrenaline induced by intravenous injection of ouabain, an Na+,K+-ATPase inhibitor, and plasma renin activity and plasma ionized calcium was examined in 16 normotensive subjects and in 16 patients with essential hypertension. These patients were divided into 11 normal-renin and five low-renin essential hypertensives. The pressor response was significantly greater in low-renin hypertensives than in normotensives and normal-renin hypertensives. Following the injection of ouabain, the pressor response was significantly increased with no change in basal levels of blood pressure, plasma noradrenaline concentration, plasma calcium and plasma parathyroid hormone in both normotensives and essential hypertensives. The pressor response to noradrenaline was negatively correlated with levels of plasma noradrenaline and calcium after the injection of ouabain as well as before the injection in normotensives and essential hypertensives. The regression line between the pressor response and that of plasma noradrenaline or plasma calcium was significantly shifted towards a higher pressor response in normotensives, but not in essential hypertensives. The changes in the pressor response to noradrenaline induced by the injection of ouabain was significantly smaller in essential hypertensives, particularly in low-renin hypertensives, compared with normotensives. These results suggest that: (1) ouabain increases the pressor response to noradrenaline; (2) this increase is related to calcium metabolism; (3) endogenous Na+,K+-ATPase inhibitor(s) might be elevated in essential hypertensives; and (4) an increase in endogenous Na+,K+-ATPase inhibitor might, therefore contribute to an enhanced noradrenaline response in essential hypertensives, particularly in low-renin hypertensives.

Blood Pressure↗
PubMed1988

Transcatheter embolization in the treatment of massive bleeding due to maxillofacial injury.

Thirty-one cases of massive bleeding due to blunt maxillofacial injuries were treated by several procedures. Blind techniques, such as nasal and/or oral packing or ligation of external carotid artery, failed to achieve hemostasis in 13 of the 18 cases (72.2%) in which they were employed before 1984. Since then, carotid angiography has documented the location of the bleeding in 12 of the 13 cases (92.3%) in which it was employed. Each of the four cases in which extravasation was visualized from the external carotid artery was successfully treated by transcatheter embolization. We conclude that selective, angiographically guided embolization can reliably achieve hemostasis in a high proportion of patients with maxillofacial injury who are in danger of exsanguination from the branches of the external carotid artery.

Adult↗
PubMed1988

Assessment of the thickness of the right ventricular free wall by magnetic resonance imaging in patients with hypertrophic cardiomyopathy.

Electrocardiogram gated magnetic resonance imaging was performed in nine healthy volunteers, in four patients with pulmonary hypertension, and in 16 patients with hypertrophic cardiomyopathy. Fifty two short axis images in diastole were examined to assess the usefulness of magnetic resonance imaging for the measurement of the thickness of the free wall of the right ventricle and the degree of hypertrophy of the right ventricular free wall in hypertrophic cardiomyopathy and pulmonary hypertension. Magnetic resonance imaging gave a clear image of 68% of the length of the right ventricular free wall, showing both the endocardial and epicardial margins. The mean (1 SD) thickness of the right ventricular free wall measured at a total of 512 points was 0.44 (0.12) cm in patients with hypertrophic cardiomyopathy, 0.29 (0.08) cm in healthy individuals, and 0.73 (0.27) cm in patients with pulmonary hypertension.

Cardiomyopathy, Hypertrophic↗
PubMed1988

[14C]butanol distribution: a new method for measurement of spinal cord blood flow.

[14C]butanol distribution was used to quantitate regional blood flow (SCBF) in the spinal cord (levels T3-5, T7-9, L1-2, L3-S) and in the sciatic nerves (NBF) of control pentobarbital sodium-anesthetized rats (group A), after 1 h of hemorrhagic hypotension (group B), after 15 min of stimulation of one sciatic nerve (group C-1), and after stimulation of one sciatic nerve plus hemorrhage, which maintained mean arterial pressure (MAP) at control (130 mmHg). Group A SCBF ranged from 52.3 +/- 3.5 (L3-S) to 67.4 +/- 2.7 (L1-2) ml.min-1.100 g-1. NBF was 8.0 +/- 0.9 ml.min-1.100 g-1. Group B SCBF was unchanged. NBF fell to 4.0 +/- 0.4 ml.min-1.100 g-1. Group C-1 SCBF was markedly elevated (range 122 +/- 23.1 to 150.1 +/- 18.7 ml.min-1.100 g-1). NBF was 33.5 +/- 4.1 ml.min-1.100 g-1 (stimulated side) and 14.7 +/- 1.4 ml.min-1.100 g-1 (nonstimulated). MAP was elevated (163 +/- 6 mmHg). In group C-2 (MAP was 130 +/- 4 mmHg), SCBF was still elevated at T3-5, L3-S, and marginally elevated at L1-2. NBF was 22.6 +/- 4.7 ml.min-1.100 g-1 (stimulated) but unchanged contralaterally. [14C]butanol distribution provides a sensitive reproducible measure of SCBF and NBF. Autoregulation of SCBF (but not of NBF) occurred in the range 60-160 mmHg MAP. Spinal cord stimulation via the sciatic nerve increased SCBF two- to threefold, but when hypertension was avoided by blood withdrawal, a modest (38%) increase in SCBF still occurred.

Animals↗
PubMed1988

Assessment of warfarin therapy under full dose using indium-111 platelet scintigraphy in patients with intracardiac thrombi.

Twenty patients in whom intracardiac thrombi were detected by indium-111 platelet scintigraphy (the first platelet scintigraphy) were prospectively studied to examine the effect of warfarin therapy under full dose on the intracardiac thrombogenicity. Eleven patients (group I) who received 2-6 mg/day of warfarin and 9 patients (group II) who did not receive warfarin had the second platelet scintigraphies 14-71 days after the first platelet scintigraphies. In group I, 10 platelet scintigraphies became negative and one remained positive for intracardiac thrombi after administration of warfarin, while in group II 8 platelet scintigraphies remained positive and only one changed to negative. The incidence of negative image at the second platelet scintigraphy was significantly lower in group II than that in group I. In group I, the degree of accumulation of platelets onto the surface of the thrombus (%IE), showed significant reduction (0.69 +/- 0.48 to 0.11 +/- 0.21) after warfarin therapy, while in group II %IE at the second scintigraphy (1.07 +/- 1.03) were not significantly different from those at the first scintigraphy (1.13 +/- 0.79). These results indicated that warfarin therapy under full dose inhibited the deposition of platelets on the intracardiac thrombi and thrombogenicity in the patients with intracardiac thrombi which were detected by indium-111 platelet scintigraphy.

Adult↗
PubMed1988

[Experimental knee pain model in rats and analgesic effect of sodium hyaluronate (SPH)].

Using the model of knee pain reaction induced by intra-articular injection of endogenous pain substances, especially bradykinin (BK) in rats, the mechanism of the analgesic effect of sodium hyaluronate (SPH) was investigated. The simultaneous administration of prostaglandin E2 with BK or hyaluronidase digestion of endogenous hyaluronic acid (HA) in our experiments brought remarkable hyperalgesia on BK-induced knee pain. These results suggest that higher sensitivity to the pain reaction is induced in a diseased joint (higher prostaglandin content, lower concentration and molecular size of HA in synovial fluid) than in a normal one. SPH definitely decreased BK-induced pain, and its analgesic effect was observed for a longer period, depending on its dose in pre-treatment and the degree of its distribution in synovial tissues. As the analgesic effect of SPH was observed in the hyaluronidase-treated joint as well, it is suggested that the increasing viscosity of synovial fluid caused by increasing HA concentration can decrease the pain even without normalizing molecular size of HA in the joint. HA oligomer and other compounds with similar viscosity or with similar polyanionic character as SPH showed no analgesic effect. From these results, it seems that the characteristic steric configurations of higher molecular HA are needed for the manifestation of the analgesic effect. SPH seems to show its analgesic effect by covering pain receptors in synovial tissues and holding endogenous pain substances in its molecule.

Analgesics↗