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Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 739 records · Page 41Linked to original sources
PubMed1993

Cancer-associated retinopathy with retinal phlebitis.

A 50-year-old man with cancer-associated retinopathy was investigated using light and electron microscopy, immunofluorescence studies, and western blotting. He had visual disturbance, ring-like scotoma, and night blindness bilaterally. There were narrowed retinal arterioles and dilated retinal venules. Oral corticosteroid therapy had positive effects. Immunostaining using the patient's serum revealed a positive reaction in the ganglion cell layer of normal retina. Western blotting showed that the patient's serum antibody reacted with normal retinal proteins of 24 and 48 kDa. Multiple metastases were evident at autopsy.

Antigens, Neoplasm↗
PubMed1993

Effect of inhaled lyso-platelet-activating factor on airway microvascular leakage in the guinea pig.

Lyso-platelet-activating factor (PAF), the precursor and metabolite of PAF, is considered inactive, although it may be converted to PAF by airway cells. We have investigated the effects of inhaled lyso-PAF on bronchoconstriction and airway microvascular leakage in anesthetized guinea pigs. Lung resistance (RL) was measured for 6 min after inhalation of lyso-PAF (0.3, 1, and 3 mM; 30 breaths) followed by measurement of extravasation of intravenous Evans blue dye into airway tissues, which was used as an index of airway microvascular leakage. Inhaled lyso-PAF caused an increase in RL and leakage of dye at all airway levels in a dose-dependent fashion, but intravenous lyso-PAF (0.25 mg/kg) had no airway effect. The maximum dose of inhaled lyso-PAF increased RL significantly by approximately 200%. The amount of extravasation of dye induced was 96 +/- 4 (SE) ng/mg of tissue in trachea, 77 +/- 8 ng/mg in main bronchi, and 65 +/- 7 and 25 +/- 1 ng/mg in proximal and distal intrapulmonary airways respectively; these values were all significantly higher (P < 0.01) than control values. These responses were completely abolished by a specific PAF-receptor antagonist WEB-2086 (2 mg/kg iv). Our results show that inhaled lyso-PAF is potent in increasing airway microvascular leakage. The effects of lyso-PAF may result from its metabolic transformation to PAF by lyso-PAF:acetyl-CoA acetyltransferase in the airway.

Administration, Inhalation↗
PubMed1993

Allergen-induced airway hyperresponsiveness in Brown-Norway rat: role of parasympathetic mechanisms.

Enhanced parasympathetic mechanisms may contribute to airway hyperresponsiveness. The present study examined whether the in vivo increase in airway responsiveness seen 18-24 h after either a single or chronic aerosolized allergen challenge protocol in actively sensitized Brown-Norway rats was due to altered parasympathetic mechanisms. The roles of central and reflex vagal mechanisms were studied by performing bilateral cervical vagotomy before measurement of airway responsiveness. Bilateral vagotomy failed to reduce the increase in airway responsiveness after either a single or chronic allergen challenge. The roles of increased neural release of acetylcholine (ACh) and increased end organ responsiveness were studied in vitro. The isometric responses of tracheal and bronchial strips to both electrical field stimulation and exogenously applied ACh from rats exposed both to single and chronic allergen challenges were compared with those from saline-exposed rats. The responses to electrical field stimulation and to exogenous ACh were not significantly enhanced 18-24 h after either protocol. We conclude that the airway hyperresponsiveness observed in this allergic rat model is not mediated through an enhancement of parasympathetic mechanisms.

Acetylcholine↗
PubMed1993

Transferable lipids in oxidized low-density lipoprotein stimulate plasminogen activator inhibitor-1 and inhibit tissue-type plasminogen activator release from endothelial cells.

Decreased fibrinolytic activity has been reported in atherosclerotic cardiovascular diseases. To determine whether oxidized low-density lipoprotein (Ox-LDL), which accumulates in atherosclerotic arteries, modulates the endothelial fibrinolytic system, cultures of human umbilical vein endothelial cells were incubated with low-density lipoproteins or lipids, and levels of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA) antigens in the conditioned medium were measured by enzyme-linked immunosorbent assay. Ox-LDL (30 micrograms protein/mL) and its extracted lipid (50 micrograms cholesterol/mL) stimulated PAI-1 release by 42 +/- 3% and 29 +/- 3% of control cultures, respectively, whereas Ox-LDL and its lipid inhibited t-PA release by 42 +/- 4% and 53 +/- 3% of control cultures, respectively. Native LDL and its lipid were inactive on their release. Ox-LDL depleted of hydrophilic lipids, which was prepared by the incubation with defatted albumin (an acceptor for hydrophilic lipids), lost both the stimulatory action on PAI-1 and the inhibitory action on t-PA. The extracted lipid from the incubated albumin, which has been found to accept the hydrophilic lipids from Ox-LDL, gained the stimulatory action on PAI-1 and the inhibitory action on t-PA. Ox-LDL depleted of lysophosphatidylcholine (LPC), which was prepared by the incubation with phospholipase B, lost the stimulatory effect on PAI-1, whereas the inhibitory effect on t-PA remained present in the Ox-LDL depleted of LPC. The incubation with synthetic palmitoyl LPC (10 microM) stimulated PAI-1 release by 85 +/- 7% of control.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Survival↗
PubMed1993

Delayed catabolism of high density lipoprotein apolipoproteins A-I and A-II in human cholesteryl ester transfer protein deficiency.

Deficiency of the cholesteryl ester transfer protein (CETP) in humans is characterized by markedly elevated plasma concentrations of HDL cholesterol and apoA-I. To assess the metabolism of HDL apolipoproteins in CETP deficiency, in vivo apolipoprotein kinetic studies were performed using endogenous and exogenous labeling techniques in two unrelated homozygotes with CETP deficiency, one heterozygote, and four control subjects. All study subjects were administered 13C6-labeled phenylalanine by primed constant infusion for up to 16 h. The fractional synthetic rates (FSRs) of apoA-I in two homozygotes with CETP deficiency (0.135, 0.134/d) were found to be significantly lower than those in controls (0.196 +/- 0.041/d, P < 0.01). Delayed apoA-I catabolism was confirmed by an exogenous radiotracer study in one CETP-deficient homozygote, in whom the fractional catabolic rate of 125I-apoA-I was 0.139/d (normal 0.216 +/- 0.018/d). The FSRs of apoA-II were also significantly lower in the homozygous CETP-deficient subjects (0.104, 0.112/d) than in the controls (0.170 +/- 0.023/d, P < 0.01). The production rates of apoA-I and apoA-II were normal in both homozygous CETP-deficient subjects. The turnover of apoA-I and apoA-II was substantially slower in both HDL2 and HDL3 in the CETP-deficient homozygotes than in controls. The kinetics of apoA-I and apoA-II in the CETP-deficient heterozygote were not different from those in controls. These data establish that homozygous CETP deficiency causes markedly delayed catabolism of apoA-I and apoA-II without affecting the production rates of these apolipoproteins.

Adult↗
PubMed1993

Freeze-drying of cephalothin sodium: granularly agglomerated crystallization during freezing. I.

Optimal conditions for the crystallization and subsequent freeze-drying of an aqueous cephalothin sodium (CET-Na) solution of supersaturated concentrations to obtain granular crystalline CET-Na have been discussed, as have the qualities of the product thus obtained. In general, CET-Na in supersaturated aqueous solution is barely recrystallized, even when in its frozen stage. Our previous report revealed that when the solution is kept at low temperatures for a long duration, the molecules begin to change structurally to as condensed a state as that of liquid crystals, and such change facilitates a spontaneous nucleation and seed-independent crystal growth in the frozen solution. These findings prompted the authors to investigate optimal CET-Na concentrations and thermal histories during the crystallization and subsequent freeze-drying process without seeding. It has subsequently been found out that optimization of the latter conditions gives granular agglomerated crystalline CET-Na contaminated with neither the amorphous nor the quasi-crystalline form. The optimized conditions are: 25-28% CET-Na concentrations; storage before the freezing process at 0 degrees C for 2 h, and subsequent storage at 20-25 degrees C for 1 h; cooling in the freezing process at a rate not faster than 0.5 degrees C/min; warming of the solution for facilitating crystallization prior to vacuum application for drying at -4 degrees C. Under these conditions, the freeze-dried product of CET-Na in granular form has been successfully obtained in a shorter freeze-drying cycle, exhibiting a faster reconstitution time than those of CET-Na prepared according to seeded crystallization followed by a conventional freeze-drying.

Cephalothin↗
PubMed1993

Freeze-drying of cephalothin sodium: granularly agglomerated crystallization during freezing. II.

The mechanism of granularly agglomerated crystallization during freezing of cephalothin sodium (CET-Na) in aqueous solution has been discussed. Our previous report noted that strict control of the following is important in order to obtain crystalline granular agglomerates of CET-Na: (1) thermal history of the solution before receiving freezing, (2) cooling rate in freezing, and (3) aging temperature level in the crystal growth step. In order to clarify the physico/chemical meanings of the individual controls, further investigations have been made: 1) with varying thermal history, aqueous 30-% CET-Na solutions were prepared for storage, first at 0 degrees C with its supersaturation and secondly at 25 degrees C, in an unsaturated state for observing any structural changes by viscosimetry, refractometry, and surface tensiometry; 2) morphological changes in ice crystals during freezing at varying cooling rates, as well as those during the crystal growth step, were observed by polarized-light cryomicroscopy and scanning electron microscopy; 3) melting, as well as crystal growth, at several aging temperature levels were observed by electrical conductometry and also by the above-mentioned techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

Cephalothin↗
PubMed1993

Piperidineacrylate derivatives as potential antiallergy agents.

A new series of piperidineacrylate derivatives was prepared and evaluated for antiallergic activity. Most of the compounds showed potent activities in the rat passive cutaneous anaphylaxis (PCA) assay. In particular, ethyl 1-[2-bis(4-fluorophenyl)methoxyethyl]-4-piperidineacrylate (1a) was more potent than oxatomide and terfenadine in this assay, and was selected for further study. Some pharmacological properties of 1a are presented.

Acrylates↗
PubMed1993

Plasma lipoprotein(a) levels and fibrinolytic activity in patients with unstable angina.

The relationship between plasma Lipoprotein(a) (Lp(a)) levels and plasminogen activator inhibitor (PAI) activity and tissue plasminogen activator (t-PA) antigen levels were studied in 15 patients with unstable angina. Plasma levels of Lp(a) (mg/dl) were significantly higher in patients with unstable angina after treatment 2 weeks than on admission (19.7 +/- 2.8 vs 14.6 +/- 2.3, p < 0.01). On the other hand, the plasma levels of PAI activity (IU/ml) and t-PA antigen (ng/ml) in patients with unstable angina were significantly higher on admission than after treatment (PAI activity: 11.4 +/- 1.4 vs 7.7 +/- 1.5, t-PA antigen: 8.7 +/- 0.9 vs 7.0 +/- 0.9, p < 0.01). We conclude that patients with unstable antigen have reduced fibrinolytic capacity, as indicated by increased PAI activity, and that the plasma Lp(a) level may be decreased due to binding with fibrin during the acute stage of unstable angina.

Adrenergic beta-Antagonists↗
PubMed1993

Williams syndrome. A middle-aged case of markedly delayed diagnosis.

A rare case of Williams syndrome diagnosed at the age of 41 is documented. The first subjective symptom was chest pain and the patient displayed many other features in addition to severe supravalvular aortic stenosis with a systolic gradient of 60 mmHg. The stenotic lesion had an area of 0.5 cm2, and was associated with dilated and tortuous coronary arteries. Extended aortoplasty was successfully performed and the postoperative course has been excellent without any cardiac symptoms. In spite of the severe cardiac lesions, this case had been largely asymptomatic and presented unusual features related to the diagnosis and management of this syndrome in an adult. The pattern of abnormalities found in this case suggested problems in relation to the calcitonin/calcitonin gene related peptide (CGRP) and the elastin gene occurring in embryonic organogenesis.

Abnormalities, Multiple↗
PubMed1993

Exacerbation of ulcerative colitis during alpha-interferon therapy for chronic hepatitis C.

We report a 34-year-old man with chronic hepatitis C who showed exacerbation of ulcerative colitis during alpha-interferon (IFN alpha) therapy. Discontinuance of the IFN alpha therapy improved his symptoms, suggesting that IFN alpha administration might worsen ulcerative colitis. The administration of sulfasalazine allowed the patient to receive IFN alpha again without flare-up of ulcerative colitis. This case suggests the possible efficacy of sulfasalazine therapy in patients with ulcerative colitis complicated by some other diseases requiring IFN alpha administration.

Adult↗
PubMed1993

Long-term follow-up study of "epileptic type" moyamoya disease in children.

Twenty-three patients with epileptic type moyamoya disease are reviewed among 200 moyamoya disease patients. Ten boys and 13 girls aged 5 months to 12 years were followed over 6 months to 17.3 years. Six had generalized seizure and 17 had focal seizure. Operations were performed within 1 year in eight patients, within 1-3 years in five, and more than 3 years after onset in 10. Nineteen patients improved and suffered no seizure without receiving antiepileptic drugs, but four patients developed true epilepsy and three of these suffered cerebral infarction. Multivariate analyses showed that toddlers aged less than 1 year and mild or severe abnormal computed tomographic (CT) findings correlated with a bad outcome. This study showed that epileptic type moyamoya disease has the same clinical features as transient ischemic attack or infarction type. Age under 1 year and CT abnormalities indicate a poor prognosis and necessity for early reconstructive surgery.

Child↗
PubMed1993

[Clinicopathological evaluation of high-range hyperthermia for advanced thoracic esophageal carcinoma].

The effectiveness of high-range hyperthermia over 45 degrees C for advanced esophageal carcinoma was clinicopathologically evaluated. Fifty-eight patients with advanced thoracic esophageal carcinoma were treated with radio-chemotherapy. They were divided into two groups: group I included 32 cases, all of whom received hyperthermia (13 cases: high-range hyperthermia); group II included the other 26 cases. The patients were given 2 Gy/day for a total of 15 sessions in 3 weeks. Bleomycin and cisplatin in combination with 5-fluorouracil have been employed as chemotherapy. Hyperthermia was performed twice a week for a total of 6 sessions. Intraluminal heating was done using Japan Crescent Inc. IH-500 T (RF, 13.56 MHz), with an intraesophageal applicator and two extra-corporeal applicators on the chest and the back. Concerning local effects, the efficacy rate was 81.3% in group I (high-range: 92.9%), and 42.3% in group II. The histologic effectiveness, when Grade 2 and 3 are determined as histologically effective, were 64.3% (high range: 85.7%) and 50.0% in group I and II, respectively.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

[Antigen-induced dynamic alterations of endothelin receptors--guinea pig lung tissues].

Endothelins (ETs) are a family of peptides with potent constrictive activity in vascular and treacheal smooth muscle. The lung tissues are abundant in these peptides and their receptors; the peptides are produced by endothelial cells and airway epithelial cells, while its receptor is mainly located on smooth muscle. Therefore, it has been proposed that endothelins act in a paracrine fashion on nearby smooth muscle, thus regulating its tone. However, little is known about its physiological and pathological roles in pulmonary functions. We hypothesized that ET plays an important role in bronchoconstriction elicited by antigen challenge. In order to test this hypothesis, we investigated tracheal contractile activities and ET-receptors by employing an animal model in guinea pigs. Here, we report that guinea pigs who were sensitized followed by multiple challenges with the antigens had alterations of ET receptor(s) with respect to number and affinity.

Animals↗
PubMed1993

Aneurysm of the right gastroepiploic artery: a case report of laparoscopic resection.

A traumatic pseudoaneurysm of the right gastroepiploic artery in a 55-year-old woman was resected using laparoscopy. The durations of anaesthesia and operation were 260 and 220 min respectively. Blood loss was minimal. The perioperative period was uneventful; the patient needed no analgesic treatment and ate her first meal on the morning of the day after surgery. She was discharged 5 days later and has progressed well for 5 months since surgery without any abnormal findings.

Abdominal Injuries↗