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Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 721 records · Page 40Linked to original sources
PubMed1993

Effects of probucol and pravastatin on plasma lipids, activities of postheparin lipoprotein lipase, and lecithin cholesterol acyltransferase and apo A-I containing lipoproteins with and without apo A-II in patients with moderate hypercholesterolemia.

In this study, plasma HDL fractions were separated by ultracentrifugation and apo A-I containing lipoproteins (A-I Lp) were then isolated using anti-apo A-I immunoaffinity chromatography. The A-I Lp were further separated into two fractions with the use of anti-apo A-II immunoaffinity chromatography. One fraction, Lp A-I, contained apo A-I without apo A-II, while the other, Lp A-I/A-II, contained both apo A-I and apo A-II. These techniques were applied to investigate the changes in HDL apoprotein composition in hypercholesterolemic subjects treated with either probucol or pravastatin. Treatment with probucol (500 mg/day) or pravastatin (10 mg/day) reduced mean plasma total cholesterol concentrations by 24% (p < 0.01) and 16% (p < 0.05), respectively. Both drugs caused some reduction in lipoprotein lipase activity, but neither had any influence on the activity of hepatic triglyceride lipase or lecithin cholesterol acyltransferase. Their effects on HDL-cholesterol levels and apoprotein composition differed markedly. Probucol significantly decreased the HDL-cholesterol concentration, the plasma apo A-I/apo A-II ratio, and the number of large particles of diameter greater than 10.4 nm. When the ratios of Lp A-I and Lp A-I/A-II for the probucol-treated subjects were compared with those in the normolipidemic controls, and with the ratios before and after administration of probucol, a remarkable decrease in the level of Lp A-I was apparent. It is presumed that the decrease in HLD-cholesterol by prolonged probucol administration reflects the decrease of Lp A-I more than the decrease of Lp A-I/A-II.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoprotein A-I↗
PubMed1993

Increased plasma plasminogen activator inhibitor activity after coronary spasm.

To examine whether ischemic attack induced by coronary spasm changes fibrinolytic activity, we examined plasma levels of tissue-plasminogen activator antigen and plasminogen activator inhibitor activity before and after hyperventilation test in patients with variant angina and in control subjects. In 12 patients with variant angina, ischemic attack associated with ST-segment elevation on the electrocardiogram was induced by hyperventilation and plasma plasminogen activator inhibitor activity levels increased significantly 15 min after the attacks (pre, 5.1 +/- 0.8; immediately after, 5.8 +/- 1.1; and 15 min after, 7.2 +/- 0.9 IU/ml, P < 0.01). In 12 control subjects, plasminogen activator inhibitor activity levels did not change. Plasma tissue-plasminogen activator antigen levels did not change in both two groups. We conclude that coronary artery spasm increases plasma plasminogen activator inhibitor activity and that it may thereby lead to the coronary thrombus formation.

Adult↗
PubMed1993

Activities of the intralaryngeal muscles during electrically induced vocalization in decerebrate cats.

Electromyograms were recorded from the intralaryngeal muscles (the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles) and the ventilatory muscles (the diaphragm (DA) and abdominal (RA) muscle) during electrically induced vocalization in precollicular postmammillary decerebrate cats. Electrical stimulation (rectangular pulses, 0.2 ms, 10-60 microA, 100 Hz, lasting 5-10 s) delivered to the rostral pons (Horsley-Clarke coordinates, A 1.0 to P 2.0, L or R 3.0 to 5.0, H -4.5 to -6.0) induced alternate inspiration and vocalization. The normal respiratory rhythm was reset to a new one and the intralaryngeal and ventilatory muscles were coordinately activated to produce vocalization. During the period of the electrical stimulation, preceding activity of PCA to DA and postinspiratory activity of DA, which were normally observed during quiet breathing, disappeared. These results suggested that the tonic electrical stimulation delivered to the rostral pons acted as a command signal to alter teh pattern generation of the ventilatory and laryngeal systems from quiet breathing to vocalization.

Animals↗
PubMed1993

Effects of microinjection of a GABA antagonist into the periaqueductal gray upon electrically-induced vocalization in decerebrate cats.

The effects of the GABA antagonist bicuculline methiodide (BIC), microinjected into the ventrolateral periaqueductal gray (PAG) on the stimulus threshold of electrically-induced vocalization were examined in unanesthetized precollicular-postmamillary decerebrate cats. To induce vocalization, repetitive electrical stimulation (0.2 ms, 100 Hz, 5-10 s duration) was delivered to the caudal portion of the PAG (30 to 300 microA) or the pontine call site (PCS) (10 to 60 microA) in the ventrolateral pontine reticular formation. Injection of 0.1 microliter of 2 mM BIC into the caudal portion of the PAG decreased the stimulus thresholds of the PCS and the injection site for about 1 h. Injection of BIC into the reticular formation near the PAG, where the electrical stimulation induced vocalization, did not decrease the stimulus thresholds of the PCS or the injection site. These results indicate that GABAergic inhibition regulates the excitability of the cells within the ventrolateral PAG, which exerts an excitatory effect on the lower brain structures that produce vocalization.

Animals↗
PubMed1993

New subtype of apical hypertrophic cardiomyopathy identified with nuclear magnetic resonance imaging as an underlying cause of markedly inverted T waves.

OBJECTIVES: The aim of this study was to elucidate the clinical importance of a new subtype of apical hypertrophic cardiomyopathy that could not be diagnosed with the classical diagnostic criteria. BACKGROUND: Apical hypertrophic cardiomyopathy is recognized by a characteristic spade-shaped intraventricular cavity on the end-diastolic left ventriculogram in the right anterior oblique projection, often associated with giant negative T waves [negativity > or = 1.0 mV (10 mm)]. As an underlying cause of giant negative T waves, an additional new subtype of apical hypertrophic cardiomyopathy has been identified. METHODS: In 40 patients with inverted T waves (negativity > or = 0.5 mV), including 26 patients with giant negative T waves, nuclear magnetic resonance (NMR) long-axis images corresponding to the left ventriculogram in the right anterior oblique projection and short-axis images at various levels, including the apical level, were obtained to define the site of hypertrophied myocardium. RESULTS: Long-axis images indicated a spadelike configuration in 17 patients, whereas this diagnostic configuration was not present in the other 23 patients. Nine of these 23 patients had significantly hypertrophied myocardium at the basal level. In the 14 remaining patients, short-axis images indicated no hypertrophy at the basal level and proved that the area of hypertrophied myocardium was confined to a narrow region of the septum or the anterior or lateral wall at the apical level (nonspade apical hypertrophic cardiomyopathy). The hypertrophied myocardium of the nonspade type was so narrowly confined that the mass did not form a spadelike configuration or could not be detected on the long-axis image. CONCLUSIONS: Nonspade apical hypertrophic cardiomyopathy was newly identified on NMR short-axis images, and this could be an additional, important underlying cause of moderately to severely inverted T waves.

Aged↗
PubMed1993

Alterations of proteoglycan synthesis in rabbit articular cartilage induced by intra-articular injection of papain.

In order to investigate the biochemical alteration of proteoglycan (PG) synthesis during cartilage repair, reversible destruction was induced by injecting papain into the knee joint cavity of rabbits. The PG synthesis in the cartilage was examined using Na2 35SO4 and high performance liquid chromatography (HPLC). PGs labeled with 35SO4(2-) (35S-PGs) were extracted from normal and papain-treated cartilage, and the amount of synthesis, ability to aggregate with hyaluronan (HA), and the composition of glycosaminoglycan and chondroitin sulfate isomer labeled with 35SO4(2-) (35S-GAG and 35S-CS isomer) were analyzed. Synthesis of 35S-PGs, especially those that were unable to aggregate with HA (nonaggregating 35S-PGs), increased in papain-treated cartilage compared with that in normal cartilage. The acceleration and qualitative change in PG synthesis in the papain-treated cartilage are considered to be responses to the supplementation of the loss of cartilage PGs induced by papain. The compositions of 35S-GAG and 35S-CS isomer of the nonaggregating 35S-PGs differed from those of 35S-PGs which were able to aggregate with HA (aggregating 35S-PGs) in the papain-treated cartilage as well as in the normal cartilage. However, the compositions of both nonaggregating and aggregating 35S-PGs in the papain-treated and normal cartilage were similar. These results indicate that most of the nonaggregating 35S-PGs in papain-treated cartilage have properties similar to those in normal cartilage and are not simple degradation products of aggregating 35S-PGs; they also suggest that the supplementary reaction for PG content in the cartilage during its repair process is not simple acceleration in PG turn-over but the enhancement of PG synthesis accompanied by alterations in aggregating ability and the compositions of GAG and CS isomer.

Animals↗
PubMed1993

Cord dorsum potentials suppressed by low power laser irradiation on a peripheral nerve in the cat.

The effects of low-power helium-neon laser irradiation on the cord dorsum potentials (CDP) evoked by electrical nerve stimulation of a distal portion of exposed sural nerve were observed in unanesthetized decerebrate cats. These evoked CDP were significantly suppressed (25.6 +/- 2.5%, p less than 0.01) during low-power laser irradiation. It is suggested that the analgesic effects of low power laser irradiation is based on the decrease of ascending signals from the spinal cord to the higher central nervous system. The suppressive effect of low power laser irradiation upon the impulse transmission of nerve fibers is discussed.

Analgesia↗
PubMed1993

Effect of thiopentone on motor evoked potentials induced by transcranial magnetic stimulation in humans.

We have studied the effect of repeated doses of thiopentone on motor evoked potentials (MEP) after transcranial magnetic stimulation in 13 patients. Thiopentone was administered i.v. in an initial dose of 2 mg kg-1, followed by repeated doses (1 mg kg-1 every 3 min) until the appearance of burst suppression on the EEG. The total dose administered was mean 10.7 (SD 2.6) mg kg-1. The magnetic coil was placed over the MEP scalp stimulation region and evoked electromyographic responses were recorded from the contralateral abductor pollicis brevis. After an initial dose of thiopentone, reproducible MEP responses were recorded in all patients, but amplitudes were reduced to 42.8% of baseline values. Further administration of repeated doses of thiopentone produced a dose-dependent decrease in success rate of MEP recordings and a significant reduction in MEP amplitude (P < 0.01). Latency did not change significantly, although there was a tendency to increase. During burst suppression on the EEG, MEP was not recorded successfully in all patients. We conclude that MEP recording during the administration of thiopentone is feasible only at a minimum dose, with a marked reduction in MEP amplitude.

Adult↗
PubMed1993

The role of HDL consisting of SP-40,40, apo A-I, and lipids in the formation of SMAC of complement.

Soluble membrane attack complex (SMAC, SC5b-9) of complement contained apolipoprotein A-I (apo A-I) and lipids. Since SC5b-9 contained no apolipoprotein A-II (apo A-II), the incorporation of apo A-I and lipids into SC5b-9 was not caused by a non-specific binding of high-density lipoprotein (HDL). The incorporation of apo A-I into SC5b-9 was confirmed by a double agar diffusion immuno-assay. SC5b-9 contained one molecule of apo A-I and 3.5% lipids by weight. The composition of the lipids was phospholipid: total cholesterol: triglyceride = 47.5:45.0:7.5, and the ratio of free cholesterol:esterified cholesterol was 22.3:77.7. Since SC5b-7 contained apo A-I and SC5b-9 free of SP-40,40 contained no apo A-I, the HDL consisting of SP-40,40, apo A-I, and lipids was incorporated into SMAC at the stage of SC5b-7 via SP-40,40 as a binding site.

Apolipoprotein A-I↗
PubMed1993

Characteristics of DNA and multiple rpoD homologs of Microcystis (Synechocystis) strains.

The base compositions of DNAs from nine Microcystis strains, as determined by high-performance liquid chromatography, were 41 to 42 mol% G+C. Chromosomal DNAs derived from these strains were found to be extremely resistant to many restriction endonucleases, and a restriction analysis revealed the presence of a dam-like methylase or both dam- and dcm-like methylases in all of the strains examined. Genomic Southern hybridization in which a synthetic oligonucleotide probe (rpoD probe) was used showed that members of the genus Microcystis might have multiple rpoD homologs, and the hybridization signal patterns observed with the DNAs of Microcystis aeruginosa strains were different from each other.

Bacterial Proteins↗
PubMed1993

A case of necrobiosis lipoidica treated with systemic corticosteroid.

A 43-year-old woman had asymptomatic eruptions on the anterior sides of both legs for 5 years. Biopsy specimens revealed the typical findings of necrobiosis lipoidica. An immunofluorescence study demonstrated no deposits of immunoglobulins, complement, or fibrinogen in vessel walls. Immunohistochemical staining revealed CD4 positive lymphocytes dominating in the lesion and strong expression of ICAM-1 on the endothelial cells, giant cells, lymphocytes and dermal fibroblasts in the lesion. The eruptions resolved remarkably with oral corticosteroid therapy.

Administration, Oral↗
PubMed1993

Elevated complement activities of sera from patients with high density lipoprotein deficiency (Tangier disease): the presence of normal level of clusterin and the possible implication in the atherosclerosis.

Clusterin (apolipoprotein J, SP-40,40), as well as apolipoprotein A-I (apo A-I) and apolipoprotein A-II (apo A-II), are apolipoprotein components of high density lipoprotein (HDL), but not of low density lipoprotein. In spite of the deficiencies of apo A-I, apo A-II and HDL in the sera of patients with Tangier disease, clusterin was found in them at normal level. While clusterin was present as the component of HDL with apo A-I in sera of normal donors, it was present as a protein which did not form a complex in sera of Tangier patients. SC5b-9 made from the sera of Tangier patients contained normal amounts of clusterin and was deficient in apo A-I, indicating that clusterin could be incorporated into the SC5b-9 complex without apo A-I. The complement activities of the sera of the patients were higher than those of normal donors. These results may be explained by the deficiencies of apo A-I, apo A-II and HDL in the patients, because they were suggested to be the inhibitors of the reactive haemolysis of complement. The elevated complement activities of the patients might be related to the severe atherosclerotic lesions in Tangier disease.

Adult↗
PubMed1993

Effects of zopiclone on slow wave sleep and spontaneous K-complexes for normal healthy young adults.

Benzodiazepine (BZD) hypnotics have been known to decrease, to some degree, human slow wave sleep (SWS) although they elevate the arousal threshold during sleep. Zopiclone (ZPC), a cyclopyrrolone hypnotic, has attracted the interest of sleep researchers because an increase in human SWS has been reported. Since the increase has not been fully confirmed by all of the studies, the authors investigated the effects of ZPC 10 mg on SWS and the K-complexes for 7 healthy young adults because there is evidence indicating that delta waves consisting of SWS and the spontaneous K-complexes are identical. SWS and st. 4 sleep did not decrease on any of the ZPC nights but st. 3 sleep showed a tendency to reduce on the 1st ZPC night. The frequency of the K-complexes decreased significantly on the 2nd ZPC night and tended to reduce on the 1st ZPC night. Moreover, a significant positive correlation was noted between the decrease rates of SWS and the K-complexes on both the ZPC nights. The authors, therefore, could not obtain any findings suggesting an increase in SWS with ZPC.

Administration, Oral↗