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Biomedical subjects

H Sugimoto

Publications and source records attributed to H Sugimoto.

At least 361 records · Page 20Linked to original sources
PubMed1985

Reactivity and activation of dioxygen-derived species in aprotic media (a model matrix for biomembranes).

In aprotic media the electrochemical reduction of dioxygen yields superoxide ion (O2-), which is an effective Brønsted base, nucleophile, one-electron reductant, and one-electron oxidant of reduced transition metal ions. With electrophilic substrates (organic halides and carbonyl carbons) O2- displaces a leaving group to form a peroxy radical (ROO.) in the primary process. Superoxide ion oxidizes the activated hydrogen atoms of ascorbic acid, catechols, hydrophenazines and hydroflavins. Combination of O2- with 1,2-diphenylhydrazine yields the anion radical of azobenzene, which reacts with O2 to give azobenzene and O2- (an example of O2--induced autoxidation). With phenylhydrazine, O2- produces phenyl radicals. The in situ formation of HO2. (O2- plus a proton source) results in H-atom abstraction from allylic and other groups with weak heteroatom--H bonds (binding energy (b.e.) less than 335 kJ). This is a competitive process with the facile second-order disproportionation of HO2. to H2O2 and O2 (kbi approximately equal to 10(4) mol-1 s-1 in Me2SO). Addition of [FeII(MeCN)4] (ClO4)2 to solutions of hydrogen peroxide in dry acetonitrile catalyses a rapid disproportionation of H2O2 via the initial formation of an adduct [FeII(H2O2)2+----Fe(O)(H2O)2+], which oxidizes a second H2O2 to oxygen. In the presence of organic substrates such as 1,4-cyclohexadiene, 1,2-diphenylhydrazine, catechols and thiols the FeII-H2O2/MeCN system yields dehydrogenated products; with alcohols, aldehydes, methylstyrene, thioethers, sulphoxides, and phosphines, the FeII(H2O2)2+ adduct promotes their monoxygenation. The product from the FeO2+-H2O2 reaction, [FeII(H2O2)22+], exhibits chemistry that is closely similar to that for singlet oxygen (1O2), which has been confirmed by the stoichiometric dioxygenation of diphenylisobenzofuran, 9,10-diphenylanthracene, rubrene and electron-rich unsaturated carbon-carbon bonds (Ph2C = CPh2, PhC = CPh and cis-PhCH = CHPh). In dry ligand-free acetonitrile (MeCN), anhydrous ferric chloride (FeIIICl3) activates hydrogen peroxide for the efficient epoxidation of alkenes. The FeIIICl3 further catalyses the dimerization of the resulting epoxides to dioxanes. These observations indicate that strong Lewis acids that are coordinatively unsaturated, [FeII(MeCN)4]2+ and [FeIIICl3], activate H2O2 to form an effective oxygenation and dehydrogenation agent.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Membrane↗
PubMed1985

Abnormalities of platelet-derived growth factors in insulin-dependent diabetes.

Platelets are involved in homeostasis of the vascular wall at various levels. An important feature of this involvement is the potential for platelet proliferation. Platelets from normal subjects contain platelet-derived growth factor (PDGF), epithelial growth factor (EGF), and transforming growth factor. We have detected the presence of an excessive growth-promoting activity in the heated supernatant fraction derived from the platelets of young, insulin-dependent diabetics. This activity is most pronounced when measured in cultures of smooth muscle cells and fibroblasts. This activity may be further separated into cationic and anionic fractions by ion exchange chromatography of the platelet-rich supernatant. The cationic factor corresponds to PDGF, whereas the anionic factor appears to be identical to EGF. Chronic, intensive insulin therapy normalizes the excessive growth-promoting activity of platelets from diabetics. Further studies are needed to evaluate the differential release of those growth-promoting factors found in platelets of normal subjects and in patients with vascular disease.

Adult↗
PubMed1985

Transesophageal echocardiographic dimensional analysis of four cardiac chambers during positive end-expiratory pressure.

The authors examined the effects of positive end-expiratory pressure (PEEP) on cardiac function by dimensional analysis of the four heart chambers using M-mode transesophageal echocardiography (TEE). The accuracy of cardiac output (CO) calculated from TEE was confirmed by its close correlation (r = 0.97) with CO, determined by the thermodilution technique. The reliability of TEE also was confirmed by excellent correlation (r = 0.95) between left ventricular end-diastolic (LVEDD) and end-systolic (LVESD) dimensions measured by the two-dimensional precordial echocardiography and those by TEE. With 10 cmH2O PEEP LVEDD decreased from its level during zero end-expiratory pressure (ZEEP), and the calculated stroke volume also decreased. These decreases were greater during 15 cmH2O PEEP, where heart rate increased slightly but significantly. Ejection fraction (EF) and fractional shortening (FS), as a whole, did not change significantly. Mean velocity of circumferential fiber shortening (mean Vcf) significantly increased and LVESD significantly decreased with PEEP. Although systolic blood pressure (SBP) significantly decreased, the (SBP-PEEP value)/LVESD ratio was not changed with PEEP. Such measures of left ventricular systolic function as EF, FS, mean Vcf, and (SBP-PEEP value)/LVESD were not decreased. Right ventricular end-diastolic dimension decreased with PEEP. Right atrial end-diastolic dimension began to decrease immediately after PEEP was initiated, whereas left atrial end-diastolic dimension began to decrease a few seconds later, suggesting that left ventricular preload decreased as a result of a decrease in right ventricular preload. The authors therefore conclude that CO was decreased as a result of the decrease in right and left ventricular preloads.

Adolescent↗
PubMed1985

Effect of plasma, serum and platelets from diabetics on DNA synthesis in cultured vascular smooth muscle cells.

Abnormalities in the regulation of proliferation of vascular smooth muscle are believed to be involved in the development of atherosclerosis. This study addresses the question of whether altered levels or activity of circulating factors in diabetes may influence the growth of vascular smooth muscle cells and fibroblasts. Plasma prepared from a group of patients with insulin-dependent diabetes mellitus was less capable of stimulating DNA synthesis in cultured vascular smooth muscle cells and human lung fibroblasts than plasma from control subjects. In contrast a platelet lysate prepared from the same patients caused significantly greater DNA synthesis than did a platelet lysate prepared from the controls. Thus both increased and decreased growth promoting activity exist in diabetes. The end result of these abnormalities may depend on the sensitivity of the target organ and platelet function, but may be related to the increased risk of atherosclerosis amongst the diabetic population.

Animals↗
PubMed1985

[Chloride and lactate composition of hypertonic sodium solution for fluid resuscitation of burn injury].

This study was performed to determine the appropriate anion composition of hypertonic sodium solution for fluid therapy of severely burned patients. Two different solutions with equal sodium concentration (Na 300 mEq/1) were prepared. The first one, low chloride solution (C1 88 mEq/1), was used for ten patients (group I); the second, high chloride solution (C1 244 mEq/1), for other ten patients (group II). Two groups had the same severity of burn injury. The infusion rate was controlled to achieve an adequate urine output (1.0 ml/kg/hour). The observation period was eight hours after injury and water and sodium intake and renal function were measured. Ccr and FENa were identical in two groups. Although both had same urine output, CH2O of group I increased. Water and sodium intake of group I were lower than those of group II. Water diuresis was related with limited chloride intake in group I and this suggested the relation between urine concentration and chloride loading in kidney. conclusively, hypertonic sodium solution with low chloride concentration requires less volume for resuscitation and may be preferred to high chloride solution in the initial therapy of burn injury.

Acid-Base Equilibrium↗
PubMed1984

Base (O.-2, e-, or OH-)-induced autoxygenation of organic substrates: a model chemical system for cytochrome P-450-catalyzed monoxygenation and dehydrogenation by dioxygen.

When catalytic quantities of superoxide ion (O.-2; or of electrons from electrolysis or of OH-) are introduced into a dry acetonitrile solution that contains excess substrate (RH), ambient air (O2), 1,2-diphenylhydrazine (PhNHNHPh), and iron(II), the substrate is rapidly and efficiently monoxygenated (e.g., triphenylphosphine----triphenylphosphine oxide, benzyl alcohol----benzaldehyde, diphenylsulfoxide----diphenylsulfone) or dehydrogenated (1,4-cyclohexadiene----benzene). The model consists of (i) an O2-activation segment that produces H2O2 from an O.-2-initiated autoxidation of disubstituted hydrazine (a model for reduced flavin), (formula; see text) and (ii) a H2O2-activation segment via the iron(II)-induced formation of ferryl ion (FeO2+), Fe(II) + H2O2----FeO2 + H2O, an effective monoxygenating agent: FeO2+ + RH----Fe(II) + ROH. The combination of i and ii provides a catalytic system for the autoxidation of organic substrates with reaction cycles that are similar to those for cytochrome P-450 monoxygenases.

Cytochrome P-450 Enzyme System↗
PubMed1984

Effects of positive end-expiratory pressure on tissue gas tensions and oxygen transport.

To determine whether positive end-expiratory pressure (PEEP) impairs peripheral tissue oxygenation, hemodynamic variables including blood and subcutaneous tissue gas tensions were measured at 0, 5, 10, 15, and 20 cm H2O of PEEP, in 9 patients who were being mechanically ventilated for acute pulmonary failure. Increasing the level of PEEP produced parallel decreases in cardiac output and oxygen delivery (DO2 = cardiac output X arterial oxygen content); however, there were no significant changes in mean arterial blood pressure (MAP), oxygen consumption (VO2), mixed-venous oxygen tension (PvO2), pH, or base excess. Subcutaneous tissue oxygen (PtO2) and carbon dioxide (PtCO2) tensions, which were directly measured in the femoral region by a mass spectrometer, also remained at their baseline levels (zero end-expiratory pressure). We concluded that peripheral tissue oxygenation is not impaired up to the level of 20 cm H2O of PEEP, even though DO2 significantly decreases.

Acute Disease↗
PubMed1984

Renal allografts with glomerulonephritic change and proteinuria.

Eight cases of renal allografts with glomerulonephritic change and proteinuria were classified into three groups according to the morphological features of the glomerular lesions. Group I (3 cases): By light microscope, remarkable reduplication of glomerular basement membrane (GBM), widening of mesangial region, and slight increase in mesangial cells, were observed. Electron microscopy revealed thickening of subendothelial space by deposition of electron-lucent material, mesangial interposition, and dense deposits in various regions (mainly in the subendothelial space). Group II (3 cases): By light microscope, crescent formation and reduplication of GBM were observed, while by electron microscope, changes of GBM similar to group I, but less remarkable, were seen. Group III (2 cases): Light microscope revealed spike formation in one case, but not in the other. With an electron microscope, subepithelial dense deposits were observed in both cases. Thickening of subendothelial space by deposition of electron-lucent material was noted in one case, while thickening of lamina densa was observed in the other case. Morphological change caused by rejection was observed in all eight cases, with six cases showing massive proteinuria and the other two showing slight proteinuria.

Adult↗