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Biomedical subjects

K Otsuka

Publications and source records attributed to K Otsuka.

At least 289 records · Page 16Linked to original sources
PubMed1988

Biochemical comparison of fibroblast populations from different periodontal tissues: characterization of matrix protein and collagenolytic enzyme synthesis.

To compare the expression of extracellular matrix components by fibroblasts from different periodontal tissues, rat molar periodontal ligament fibroblasts (RPL) and rat gingival fibroblasts (RGF) were isolated and cultured from individual animals. Pulse-chase experiments using [35S]methionine as a precursor revealed that confluent populations of early passage cells of both cell types synthesized similar amounts of collagen, fibronectin, and SPARC/osteonectin. Qualitative and quantitative differences were apparent in the relative proportions of type III collagen, in the rates of procollagen processing, and in the synthesis of a small number of unidentified proteins observed by sodium dodecyl sulphate--polyacrylamide gel electrophoresis. Collagen constituted 24-26% of the radiolabelled proteins secreted by both cell types, type I being the predominant collagen, with lower amounts of type III (3-8% RGF, 8-18% RPL) and type V (approximately 1%) collagens. Procollagen processing in the culture medium of RPL cells was more rapid than for RGF cells, but was increased in multilayered cultures of both RPL and RGF. In multilayered cultures, collagen TCA fragments, indicative of tissue collagenase activity, were also identified. Active and latent tissue collagenases and a latent form of a novel collagenolytic enzyme (matrix metalloendoproteinase-V) that cleaves native TCA fragments were demonstrated in these cultures. Addition of either concanavalin A (10(-6) M) or retinoic acid (10(-5) M) to the culture medium stimulated the secretion of the latent collagenolytic enzymes. Collagenase inhibitor was also synthesized by both RGF and RPL cells. SPARC/osteonectin, a 40-kilodalton glycoprotein, represented 0.5-1.0% of the secreted radiolabelled proteins of both cell types.

Animals↗
PubMed1988

Haemodynamic effects of new beta-blockers with vasodilatory properties in essential hypertension.

Six weeks of treatment with carvedilol, N-696, celiprolol, dilevalol, acebutolol, urapidil, doxazosin and altiopril reduced blood pressure with various changes in heart rate. Cardiac index decreased and total peripheral resistance index (TPRI) stayed at the pretreatment levels in the carvedilol, N-696 and acebutolol groups, whereas TPRI tended to decrease in the celiprolol (p less than 0.05), dilevalol (p less than 0.05), urapidil, doxazosin (p less than 0.05) and altiopril groups; cardiac index was unchanged in these groups. As carvedilol and N-696 have no beta 1-selectivity and no intrinsic sympathomimetic activity (ISA), their direct vasodilating property (and the possible alpha-blocking activity of carvedilol) may precipitate in minimising an increase in TPRI induced by vascular beta 2-blockade and suppressed cardiac pump function. Celiprolol and dilevalol, with beta 2-selective ISA, reduced cardiac index slightly and insignificantly, and decreased TPRI. These results indicate that ISA on vascular beta 2-receptors may induce vasodilatation and ISA on cardiac beta 2-receptors may counteract cardiac beta 2-blockade. Differences in haemodynamic responses between these drugs with ISA and vasodilators such as alpha-blocking agents (urapidil and doxazosin) and an ACE inhibitor, altiopril, may be attributable to manifestation of cardiac beta-blockade as observed in the drugs with ISA.

Adrenergic beta-Antagonists↗
PubMed1987

Arrhythmogenic properties of disordered breathing during sleep in patients with cardiovascular disorders.

The purpose of this study was twofold: to establish an ECG respiration monitoring system, and to evaluate the clinical usefulness of this system. Our purpose was to determine how many patients with cardiovascular disorders may have unrecognized sleep apnea and whether such apneic episodes are an important cause of cardiac arrhythmias. The study group included 81 patients, age range 40-95 years, and 13 healthy males, age range 52-72 years. The 24-h ECG respiration recordings were obtained with the two-channel holter recorder. Airflow at the nose using a nasal thermister or chest wall movement by impedance pneumography was recorded as respiration record on the second channel. Sleep apnea was observed 69% and 77-100% in the control subjects and patients with cardiovascular disorders, respectively. Episodes of sleep apnea were most frequent in the patients with old myocardial infarction. Grading of apneas was defined according to the length of apnea. Short duration apneas were observed only in the control subjects, but longer apneic episodes were observed in patients with cardiovascular disorders. Bradyarrhythmias observed were to be relative to apneic episodes longer than 20 s, while ventricular arrhythmias were observed only in the patients with old myocardial infarction, coincident with apneas lasting longer than 40 s. Atrioventricular conduction disturbances were also observed to be related to the occurrence of sleep apnea. These results suggest that 24-h ECG respiration monitoring is useful not only for the observation of sleep apneic episodes, but also in clarifying the relationship between cardiac arrhythmias and apneic episodes.

Adult↗
PubMed1987

Isoenzyme studies in human leukemia-lymphoma cell lines--V. Induction of differentiation by T-cell derived differentiation-inducing activity.

A panel of human leukemia cell lines from various lineages (T-cell, pre B- and Non-T/Non-B cell, myelomonocytic and erythroleukemia cell lines) were utilised as model systems of the distant effects of differentiation-inducing activity (DIA) produced by the T-leukemia cell line HUT-102. DIA inhibited cell proliferation and induced distinct morphological changes which were more pronounced in the myelomonocytic and erythroleukemia cell lines than in the lymphoid cell lines. DIA triggered in the myelomonocytic and erythroleukemia cell lines an increase in the number of NBT-reducing cells and caused strong adherence to plastic surface. The T-cell lines showed aggregation of cells in floating clusters. In the isoenzyme analysis of the enzymes carboxylic esterase and acid phosphatase, it was found that DIA stimulated the new expression of isoenzymes and a stronger staining intensity of several isoenzyme bands in all cell lines, however, at varying degrees. HL-60 and HEL displayed newly a monocyte-specific isoenzyme. Several myelomonocytic and erythroleukemia cell lines were triggered to express the tartrate-resistant acid phosphatase isoenzyme. The cell kinetic, morphological, functional and isoenzymatic data demonstrated that DIA effected the development of the different blood cell types. However, it appears that the cells reached a new differentiation block after acquired expression of differentiation-linked features; the lymphoid cell lines were more limited in their response to DIA than the myeloid and erythroid cells.

Acid Phosphatase↗
PubMed1986

The applicability of noninvasive His bundle electrogram to assessing the effect of digitalis on atrioventricular conduction.

His bundle electrograms were recorded by a signal averaging technique using the Takayasu vectorial lead system, and effects of ouabain on the atrioventricular conduction were investigated using Wistar rats. Ouabain was given intraperitoneally at 30 min intervals in doses of 1-40 mg/kg. When ouabain dosage was increased to 20 mg/kg, the prolongation of PQ interval became prominent and P waves were hidden on the preceding T waves. Dose-related prolongation of PQ and AH intervals was observed in the 1-15 mg/kg dosages. Ouabain-induced ventricular arrhythmias occurred in the 30 mg/kg dosage. Dose-related prolongation of QRS duration and HV interval was observed in the 1-25 mg/kg dosages. These prolongations were significant by the analysis of variance (p less than 0.01). Prolongation of PQ and AH intervals is probably due to a digitalis-induced increase in parasympathetic nerve activity. However, the reason for the prolongation of HV interval and QRS duration was uncertain. Direct effects of ouabain on the conduction system, or central nervous system effects of ouabain on cardiovascular function were speculated. These results suggest the applicability of the noninvasive record of His bundle electrogram to assessing the digitalis effect even on the human atrioventricular conduction.

Animals↗
PubMed1986

Experimental study on the relationship between cardiac arrhythmias and sleep states by ambulatory ECG-EEC monitoring.

The relationship between cardiac arrhythmias and sleep states was investigated in rats using the ambulatory ECG-EEG monitoring system under the 14/10 light-dark illumination schedule. Records of 14 rats obtained over 94 days were analyzed. Bradyarrhythmias (SA block and AV block) and ventricular arrhythmias [ventricular premature contraction (VPC) and short run of VPCs (ventricular tachycardia, VT)] were observed. Average number of episodes of bradyarrhythmia per day was 7.5, and the ratio of SA block to AV block was 34.9% to 65.1%. Average VPC or VT occurrence per day was 0.9 or 0.1 times, respectively. Sleep states were divided into alertness, slow-wave sleep, and paradoxical sleep, and the relationship between sleep states and arrhythmias was investigated. Bradyarrhythmias appeared predominantly during paradoxical sleep, while ventricular arrhythmias appeared during alertness as well as paradoxical sleep. Bradyarrhythmic episodes decreased by right or left vagotomy 78% or 70%, respectively. Sinus bradyarrhythmias disappeared almost completely by the right vagotomy, while the occurrence of AV block decreased by the right or left vagotomy. Circadian rhythms in arrhythmias were also analyzed by the cosine-fitting technique, and significant circadian rhythms were demonstrated in both bradyarrhythmias and ventricular arrhythmias. Acrophases were 9:56 A.M. and 1:47 A.M., respectively. Occurrence of VT was rare, but the most frequent incidental time zone was immediately following transition from light effects (rest) to dark (activity). This knowledge of circadian rhythm effects in arrhythmias must be incorporated into improved treatment of arrhythmias.

Animals↗
PubMed1986

Ventrolateral medullary neurons projecting to the medial preoptic/anterior hypothalamic area through the medial forebrain bundle: an electrophysiological study in the rat.

A total of 152 ventrolateral medullary neurons was antidromically stimulated from both the medial preoptic/anterior hypothalamic area (MPOAH) and the medial forebrain bundle (MFB) in urethane anesthetized rats. These neurons were located primarily dorsal to the lateral reticular nucleus and could be readily classified in at least two groups, type I and type II cells on the basis of electrophysiological properties. The action potentials of type I cells had a shorter duration, and their conduction velocities ranged from 0.45 to 3.1 m/s. By contrast, type II cells, most predominantly observed, were characterized by a longer duration and an unusual shape of their action potential, and the antidromic propagation into the somatodendritic complex was often blocked. The conduction velocity (mean = 0.21 m/s) and absolute refractory period (mean = 2.63 ms) of type II cells are consistent with them having fine non-myelinated axons. Injection of 6-hydroxydopamine (6-OHDA), but not 5,7-dihydroxytryptamine, directly into the MFB blocked antidromic responses of 57% of type II cells tested. The residual type II cells whose antidromic responses were not affected by 6-OHDA were located significantly rostral to the 6-OHDA sensitive cells. Neither antidromic response of type I cells tested, on the other hand, was affected by 6-OHDA. The majority of type I cells were dramatically activated by noxious pinches of the tail, whereas the noxious stimuli produced no detectable change in the firing of type II cells. These data demonstrate that ventrolateral medullary neurons projecting to the MPOAH through the MFB are comprised of at least three distinct populations: 6-OHDA resistant fast conducting cells with somatic afferents, 6-OHDA sensitive and resistant slow conducting cells.

Action Potentials↗
PubMed1986

Role of the suprachiasmatic nuclei of the hypothalamus on diurnal rhythm in cardiac arrhythmias.

Ambulatory EGG and EEG recordings were recorded under a 14/10-h light-dark illumination schedule using rats. The rats consisted of two groups: a suprachiasmatic (Sch) lesioned group (n = 5) and a normal control group (n = 5). Bilateral Sch nuclei were lesioned electrically (DC, 2.5 mA, 30 s for each) using a pair of platinum electrodes 0.3 mm in diameter. After recovery from surgery, recordings of ECGs (leads I, II, and III) and EEGs from the cortex and the left dorsal hippocampus were continued for 6 days. Diurnal periodicity in bradyarrhythmia (sinoatrial block, atrioventricular block) and heart rate was analyzed by the least square fit of 24-h cosines. Significant diurnal rhythm was observed in control rats, whereas Sch-lesioned rats showed no significant diurnal rhythm. The integrity of the Sch nuclei, therefore, is necessary for the generation and/or the expression of diurnal periodicity in bradyarrhythmia in rats.

Animals↗
PubMed1986

[Effect of carbon tetrachloride on blood coagulation and fibrinolytic activities in rats].

Blood coagulation and fibrinolytic activities were studied in rats with hepatic injury induced by carbon tetrachloride (CCl4). Acute hepatic injury was induced by single oral administration of 0.5, 1.0, 2.0 and 3.0 ml/kg of CCl4. Experiments were performed on the parameters of blood coagulation activities (TEG, HPT, TT, PRCT, PT, PTT, fibrinogen, factor XIII and AT III) and those of fibrinolytic activities (PLG, alpha 2PI) and plasma total protein, GOT, GPT, Ht, L/B ratio. All determinations were measured at 24 hr after administration of CCl4. Blood coagulation and fibrinolytic activities in rats were weakened in accordance with the dosage of CCl4 administration. Below CCl4 administration of 1.0 ml/kg, the GOT and GPT values increased in accordance with the dosage. However, with CCl4 administration of above 1.0 ml/kg, these values stayed at almost the same level. On the other hand, the relationship between the dosage of CCl4 and logarithmic values of HPT, PT, PTT, factor XIII and PLG all showed a good straight line.

Animals↗