Search PubMed⌕ Search

Biomedical subjects

Y Miyauchi

Publications and source records attributed to Y Miyauchi.

At least 145 records · Page 8Linked to original sources
PubMed1990

Enzymatic removal of bilirubin toxicity by bilirubin oxidase in vitro and excretion of degradation products in vivo.

The toxic effects of the degradation products of bilirubin that were formed by reaction with bilirubin oxidase were investigated with the C 1300 mouse neuroblastoma cell line by examining the following parameters: growth inhibition, morphologic characteristics, membrane transport, DNA synthesis, and protein synthesis. The addition of bilirubin to the cells resulted in definite cytotoxic effects on all of these parameters in a dose-dependent fashion; the addition of bilirubin oxidase reversed the toxic effects on the C 1300 cells in vitro. Furthermore, we found that most of these enzymatic degradation products of bilirubin were excreted by the kidney into the urine in a few hours after intravenous injection of the degradation products; in contrast, no intact bilirubin was excreted. Thus, these findings suggest that hyperbilirubinemia in newborn infants (kernicterus) may be prevented by administering polyethylene glycol-conjugated bilirubin oxidase, with a longer plasma half-life which has been reported previously to oxidize bilirubin to its nontoxic components in the bloodstream.

Animals↗
PubMed1990

A monoclonal antibody, RbM2, specific for a lysosomal membrane antigen of rabbit monocyte/macrophages.

An anti-macrophage monoclonal antibody (mAb), RbM2, was produced using thioglycolate-elicited rabbit peritoneal macrophages as immunogen. The immunohistochemical approach revealed an intense reactivity of this mAb to macrophages, particularly those engaged in phagocytosis, in different organs and tissues, and to peripheral blood monocytes. Immunoelectron microscopy demonstrated reaction products of RbM2 in the lysosomes of macrophages and monocytes. This selective reactivity with the mAb was further confirmed in various experiments by endocytosis of Latex particles with different diameters or IgG-coated sheep erythrocytes. The results indicate that RbM2 recognizes a lysosomal membrane antigen of 50,000 molecular weight (MW). In contrast, dendritic cells, such as follicular dendritic cells (FDC) of lymphoid follicles, interdigitating cells (IDC) of lymphoid T zones, or epidermal Langerhans' cells, were not reactive with the antibody. Thus, RbM2 is useful not only in differentiating the phagocytic macrophages from the immunologically accessory dendritic cell populations but also in identifying lysosomes and their related structures in macrophages.

Animals↗
PubMed1989

Neutrophil producing capacity of 5-lipoxygenase metabolites of arachidonic acid after major surgery.

It is well known that patients who undergo surgical operations have a high risk of infection and sepsis. One explanation for this high risk may be a depression of neutrophil functions at the postoperative period. In the present study, the effects of surgical stresses on neutrophil functions were studied in ten patients who underwent general anesthesia and major surgery. The neutrophil functions especially focused on were the producing capacities of 5-lipoxygenase metabolites of arachidonic acid such as Leukotriene B4 (LTB4), LTC4, LTD4, 6-trans-LTB4, and w-oxidation products of LTB4. Neutrophils were stimulated with calcium-ionophore A23187 (2x10(-5) M) in the presence of arachidonic acid (5x10(-5) M) for 5 minutes at 37 degrees C. The arachidonic acid metabolites were extracted by methanol. After centrifugation, the supernatant of the mixture was concentrated and applied to a C-18 column on reversed phase high performance liquid chromatography (RP-HPLC) system, monitoring the absorbance at 280 nm. In all cases, the LTB4 production significantly increased postoperatively with an increment of 6-trans-LTB4 and w-oxidation products of LTB4. The LTC4 production, by contrast, significantly decreased postoperatively. LTD4 production was observed at neither pre nor postoperative periods. The total amount of LTA4 metabolites at the postoperative period, including LTB4, LTC4, and 6-trans-LTB4, increased 1.2 times compared with that at preoperative period. This indicates the possibility of the alteration of the neutrophil metabolism in 5-lipoxygenase cascade, the increment of LTA4 generation and the change of LTA4 metabolism from LTC4 synthesis to LTB4 generating pathway.

Abdominal Neoplasms↗
PubMed1989

Neural crest origin of clear cell sarcoma of tendons and aponeuroses. Ultrastructural and enzyme cytochemical study of human and nude mouse-transplanted tumours.

In order to clarify the histogenesis of clear cell sarcoma of tendons and aponeuroses (CCS), two cases of human and one nude mouse-transplanted CCS line were studied using an ultrastructural and enzyme cytochemical approach. Most of the tumour cells obtained from the primary and transplanted CCS demonstrated melanosomes in various stages of development within the cytoplasm, whereas no melanosomes could be identified in the metastatic CCS. However, cholinesterase and tyrosinase activities could be demonstrated not only in the melanotic primary and transplanted CCS but also in the amelanotic metastatic CCS. The results therefore support the hypothesis that CCS is a soft tissue tumour derived from the neural crest.

Animals↗
PubMed1989

Complement activation and neutrophil dysfunction in burned patients with sepsis--a study of two cases.

The changes in complement components and neutrophil functions were investigated in two cases of flame burn patients who died of multiple organ failure following septic shock. In the period of bacteremia, complement activation was observed in the plasma of both patients, using an immunoblotting method demonstrating C3a-related antigens. Coincidently, reduced neutrophil function and a decrease in the superoxide and leukotriene producing capacity, were also observed. An in vitro study showed that the capacity to produce superoxide and leukotriene became reduced in normal neutrophils after exposure to complement activated serum. These observations suggested that complement activation, probably brought about by massive bacterial infection, induced the impairment of neutrophil functions and resulted in a further breakdown of the host defence system, thereby leading to sepsis.

Adult↗
PubMed1989

Effect of cold cardioplegic solution and hypothermia on response to acetylcholine in perfused epicardial coronary artery of pig.

The effect of cold cardioplegic solution and hypothermia on the response to acetylcholine, a major postganglionic neurotransmitter of the parasympathetic nervous system, was studied using perfused epicardial coronary arteries of pigs. Cold crystalloid cardioplegic solution (5 degrees C) and hypothermia including topical cooling with slushed ice significantly augmented the coronary flow reduction by acetylcholine at one and two hours after rewarming. Cold Krebs-Henseleit solution (5 degrees C) with hypothermia showed similar effects. However, cardioplegic solution at 37 degrees C did not affect the responsiveness. The coronary flow reduction induced by potassium chloride (60 mmol/L) did not change even after the administration of cold cardioplegic solution (5 degrees C) or cold Krebs-Henseleit solution (5 degrees C), indicating that cooling did not necessarily augment the coronary contractile response generally. It is concluded that cooling and subsequent rewarming can potentiate the contractile response of the coronary artery of the pig to acetylcholine. This suggests that cold cardioplegic solution with hypothermia can promote intraoperative coronary spasm upon activation of the parasympathetic nervous system.

Acetylcholine↗
PubMed1989

Postischemic administration of idazoxan, an alpha-2 adrenergic receptor antagonist, decreases neuronal damage in the rat brain.

The effect of an alpha-2 receptor antagonist, idazoxan, on ischemic neuronal damage in the hippocampus and neocortex was studied in rats following 10 min of forebrain ischemia. Idazoxan was given 0.1 mg/kg i.v. immediately after recirculation, followed by 48 h of continuous infusion at a rate of 10 micrograms/kg/min. A histopathological examination of the CA1 region of the dorsal hippocampus and neocortex from each hemisphere was made on paraffin-embedded sections following 7 days of survival. In ischemic animals receiving an infusion of saline, 71% of the neurons in the hippocampal CA1 region were degenerated. In contrast, in the idazoxan-treated animals only 31% of the neurons were irreversibly damaged (p less than 0.01). We conclude that postischemic administration of the alpha-2 antagonist idazoxan protects neurons against damage following cerebral ischemia. Rapid postischemic administration of alpha-2 adrenergic receptor antagonists could be an effective treatment after stroke and cardiac arrest.

Adrenergic alpha-Antagonists↗
PubMed1989

Noradrenaline metabolism in neocortex and hippocampus following transient forebrain ischemia in rats: relation to development of selective neuronal necrosis.

Noradrenaline (NA) metabolism in the neocortex and hippocampus was examined in rats at 1, 24, and 48 h following 15 min of reversible forebrain ischemia. As assessed by the ratio of accumulated 3,4-dihydroxyphenylalanine (DOPA) to the tissue NA level after inhibition of DOPA decarboxylase, the NA turnover rates were markedly increased (120-148% above the control) at 1 h postischemia in both the neocortex and hippocampal formation (CA1 and CA3 plus dentate gyrus). The DOPA:NA ratio went back to control levels after longer postischemic survival times. The ratio between levels of the deaminated NA metabolite, 3,4-dihydroxyphenylethyleneglycol (DOPEG), and NA, which gives another measure of NA turnover rate, showed similar changes. In the neocortex and the CA3 plus dentate gyrus, the DOPEG:NA ratio was markedly increased (89-118%) 1 h after the ischemia, but this change had disappeared at 24 and 48 h. Thus, both the DOPA accumulation experiments and the NA and DOPEG measurements indicate that following transient forebrain ischemia, there is an increased NA turnover in the hippocampus and cortex only in the early recirculation period and not after longer postischemic survival times. The degree of neuronal necrosis in the CA1 region was examined light microscopically on celestine blue-acid fuchsin-stained sections at 24, 48, and 96 h following the ischemic insult. The neuronal damage in CA1 was sparse after 24 h of recovery, had increased markedly after 48 h, and was very pronounced at 96 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Ultrastructural cytochemistry of epithelial gland-like component in synovial sarcoma].

In order to analyze the mucoid substance in the epithelial component of synovial sarcoma, electron microscopic and cytochemical studies were made on three of these neoplasms. The mucoid substances in the glandular lumen were intensely stained with ruthenium red (RR), appearing as granular, fibrillar and amorphous structures. RR staining of proteoglycans was diminished after treatment with chondroitinase AC or ABC, and was partially diminished by exposure to streptomyces hyaluronidase. Trypsin treatment did not affect RR staining of proteoglycans in the lumen. On thin sections stained with periodic acid-thiocarbo-hydrazide-silver proteinate (PA-TCH-SP), deposits of reaction product were observed on the mucoid substances within the lumen, and were localized in the Golgi complex, including the rough endoplasmic reticulum, small vesicle and lysosome-like dense body. Trypsin digestion decreased the stain intensity of PA-TCH-SP. These results indicate that the lumen of the gland-like component contains glycoproteins as well as proteoglycans mainly consisting of chondroitin sulfate and hyaluronic acid, and suggest that GERL (Novikoff) is closely related to production, storage and transport of glycoproteins in the cytoplasm of tumor cells.

Adolescent↗
PubMed1989

[Transplantable osteosarcomas in rats. I. The growth behavior of spontaneous and 4-HAQO induced osteosarcomas in rats].

While there are a number of experimental animal models for osteosarcoma development, the available rat systems are limited both in number and applicability. The present report concerns our attempts to establish an appropriate rat model to allow development of new experimental approaches to human osteosarcoma. A spontaneously occurring osteosarcoma (J. H. 1-OS) was found in a 35 week old male rat. The tumor could be transplanted and grew well and although the bone forming activity decreased after the 18th generation, the growth potential remained high.

4-Hydroxyaminoquinoline-1-oxide↗
PubMed1989

[Breast cancer associated with pregnancy].

Two cases of breast cancer associated with pregnancy were reported and the immunological assessment was performed in the second case. Case 1: A 36 year-old woman in the first trimester of pregnancy and having a large axillary mass and breast lump was admitted. She was diagnosed as having Stage IIIb breast cancer. After interruption of pregnancy, she received an extended radical mastectomy and radiotherapy. However, she died nine months after surgery for brain and liver metastases. Case 2: A 30 year-old woman in her second trimester of pregnancy was admitted for a large breast mass. She was diagnosed as having Stage IIIa breast cancer. Interruption of pregnancy was again necessary to perform surgery followed by chemotherapy. After an extended radical mastectomy she was placed on a combination chemotherapy regimen with cyclophosphamide, adriamycin and 5-FU. In both cases tumors began to develop rapidly at pregnancy. Immunological studies in Case 2 showed a depression of T-lymphocyte function and NK cell activity. Our study suggests that the depression of cell-mediated immunity during pregnancy may promote tumor growth.

Adenocarcinoma↗
PubMed1989

[Benefits and limitation of extracorporeal circulation with autologous blood using low priming membrane oxygenator].

The high incidence of hepatitis following cardiopulmonary bypass has stimulated attempts to develop a technique of perfusion without homologous blood. Between October, 1987 and March, 1988, 36 patients underwent open heart surgery without homologous blood transfusion were investigated. Patients with infective endocarditis and urgent surgical cases were excluded from this study. Out of 36 patients using hemoconcentrator, autologous blood and the Variable Prime Cobe Membrane Lung (VPCML), 28 patients (78%) could avoid homologous blood transfusion during the operation and 24 patients (67%) received no homologous blood throughout their hospital stay. Thus, the application of lower volume extracorporeal oxygenator system, reinfusion of residual pump volume using hemoconcentrator and predonated autologous blood could achieved cardiac surgery without homologous blood transfusions in the majority of patients. Moreover, the VPCML had sufficient gas transfer in adult patients with body weight ranging from 37 kg to 70 kg. In renal function, serum creatinine levels in patients without homologous blood were within normal limits throughout 1 month after surgery. However, creatinine level was significantly elevated at the third postoperative day in the homologous blood transfusion group. Thus, these results suggest that application of VPCML and hemoconcentrator combined with predonated autologous blood is useful to achieve open heart surgery without donor blood.

Blood Transfusion, Autologous↗
PubMed1989

[Surgical treatment of thoracoabdominal aortic aneurysm].

Graft replacement for thoracoabdomital aortic aneurysm was performed in 8 patients between 1982 and 1989. Five patients in our series underwent reattachment of the branch vessels to openings made in the graft. Partial bypass or external shunt was used in 6 patients during aortic cross-clamping. Selective blood perfusion to the branch vessels was performed in 5 patients intraoperatively. Neither hospital death nor postoperative paraplegia was found in our series. One patient without selective perfusion of abdominal branch vessels during reattachment to the graft developed an acute jaundice postoperatively, but 4 of the 5 patients receiving selective perfusion of branch vessels developed no complication related to abdominal ischemia. These results suggest that intraoperative blood perfusion of aortic branch might be useful for prevention of anoxic complication of the abdominal organs after surgery of thoracoabdominal aortic aneurysm.

Adult↗
PubMed1988

Effects of perivascular nerve stimulation on the flow rate in isolated epicardial coronary arteries of pigs.

The effect of perivascular nerve stimulation on coronary contraction was examined by perfusing the isolated epicardial coronary artery of pigs. Coronary flow decreased in a frequency-dependent manner after electrical stimulation, with a maximum percent flow reduction of 23.8 +/- 1.1% (n = 10) at 20 Hz. The reduction in flow rate was not inhibited by phentolamine nor propranolol but was inhibited by atropine. Neostigmine enhanced the flow reduction induced by nerve stimulation. Acetylcholine reduced the flow rate dose dependently but norepinephrine showed no effect. We conclude that perivascular nerve stimulation of the epicardial coronary artery of pigs causes a modest flow reduction through activation of a cholinergic mechanism.

Acetylcholine↗
PubMed1988

Effect of surgery on neutrophil functions, superoxide and leukotriene production.

Perioperative changes of neutrophil function were investigated in 28 patients who underwent major surgery, particularly focusing on the potential capacity for superoxide and leukotriene production, which seem to be important in host defence. The superoxide-producing capacity of neutrophils, which was examined using N-formyl-peptide or phorbol myristate acetate as an attractant, significantly decreased postoperatively to 55 and 69 per cent of the pre-operative values, respectively. The leukotriene-producing capacity of neutrophils, which was stimulated with calcium ionophore A23187 in the presence of arachidonic acid, significantly changed postoperatively. The leukotriene B4 (LTB4) production increased together with an increment of production of 6-trans 6-trans LTB4, however, increased postoperatively to 1.2 times the (LTC4) production decreased postoperatively. The total production of leukotriene A4 (LTA4) metabolites consisting of LTB4, LTC4, and 6-trans LTB4, however, increased postoperatively to 1.2 times the pre-operative values. This indicates that neutrophils in the postoperative period have a higher capacity for LTA4 production but a lower capacity for superoxide production than those in the pre-operative period.

Adult↗
PubMed1988

Production of an eosinophil chemotactic lymphokine by a monocyte-derived factor from patients with hypereosinophilia.

Peripheral OKT4-positive T lymphocytes from patients with hypereosinophilia spontaneously and selectively produced an eosinophil chemotactic factor (ECF) with chemokinetic activity. The molecular weight of the ECF was about 45,000 to 70,000. A possible mechanism of its spontaneous production by T lymphocytes was analyzed. Culture supernatants of blood monocytes from the patients showed little or no ECF activity, but they had a potency to induce the ECF production from T lymphocytes from normal donors when the cells were stimulated by the supernatants, which suggests that a monocyte-derived soluble factor (MDF) stimulated T lymphocytes to produce an ECF resembling this spontaneously produced ECF from the patients. MDF seemed to be a synthesized protein by the cells. Gel filtration indicated that molecular weight of MDF ranged between 70,000 and 100,000. MDF activity was stable at 56 degrees C for 30 min but more, supernatants of stimulated monocytes by lipopolysaccharide or silica particles failed to show ECF-producing activity, whereas they showed evident lymphocyte-activation activity. Neither recombinant IL-1 nor IL-2 had ECF and ECF-producing activity. From the present experiments, it was suggested that MDF was at least partly involved in the induction of ECF production by OKT4-positive T lymphocytes in patients with hypereosinophilia.

Adult↗
PubMed1988

Complement conversion and leukocyte kinetics in open heart surgery.

Complement conversions and a pulmonary leukocyte sequestration were observed during cardiopulmonary bypass (CPB) in all of twenty patients who received open heart surgery. A systemic neutropenia was initially observed in the early phase of CPB, and it subsequently turned into a systemic neutrocytosis during the late phase of it. A significant leukocyte sequestration was found in the pulmonary circulation during CPB coincidently with the systemic neutropenia. The contribution of the transpulmonary sequestration to the leukopenia was major, being as high as 80 per cent. Plasma C3, C4, and CH50 levels rapidly decreased following the commencement of CPB. Alterations of the C3 molecule in the patients' plasma were demonstrated using the immunoblotting method. The appearances of C3a and C3b with the apparent molecular weights of 10,000 and 170,000 respectively, might be evidence of the complement activation during CPB. Another type of alteration in the C3 molecule was observed in the generation of a new fragment with the apparent molecular weight of 14,000. The appearance of this fragment, which did not share common epitopes with C3a, might suggest the consumption of complement components during CPB, unrelated to the activation of the complement systems.

Adult↗