PubMed Health⌕ Search

Biomedical subjects

Y Toyama

Publications and source records attributed to Y Toyama.

15 recordsLinked to original sources
PubMed1979

Differential response of myofibrils and 10-nm filaments to a cocarcinogen.

Multinucleated myotubes containing large numbers of striated myofibrils and large numbers of longitudinally-oriented 10-nm filaments were treated with the cocarcinogen phorbol-12-myristate-13-acetate (PMA) for 24, 48 or 72 hours. The inhibitory effects of PMA on the accumulation of myofibrils was evident within 24 hours, and by 72 hours virtually all striated myofibrils had disappeared. In contrast, the density of the 10-nm filaments was greatly enhanced in these myofibril-depleted myotubes. These effects were not due to a generalized cytotoxicity, for PMA stimulated the replication of the presumptive myoblasts and fibroblasts present in these cultures. 24 hours after removing the PMA, these myotubes assembled a new set of striated myofibrils and the density of 10-nm filaments diminished proportionately.

Animals↗
PubMed1979

Crystalloids of actin-like filaments in the Sertoli cell of the swine testis.

Normal swine testes, congenital cryptorchid swine testes, and normal human tests were exposed to HMM (heavy meromyosin) after either glycerination or saponin treatment in order to determine whether the fine filaments composing the crystalloids in the Sertoli cells of the cryptorchid swine testes bind HMM to form arrowhead complexes. Short bundles of microfilaments observed in the basal part of the Sertoli cells in both normal and cryptorchid testes also bind HMM. Similar bundles of HMM-bound filaments are observed in the vicinity of spermatocytes. The periodicity of the arrowhead complexes is about 35 nm, and all arrowheads on a given filament point in the same direction. In addition, the polarity of the HMM-bound filaments in a given crystalloid or bundle is uni-directional. A mechanism for the formation of the swine crystalloids has been strongly support this hypothesis. Fine filaments of Charcot-Boettcher's crystalloid in human Sertoli cells did not bind HMM. Therefore the fine filaments of the human crystalloid are not actin-like in nature.

Actins↗
PubMed1979

Redistribution of intermediate filament subunits during skeletal myogenesis and maturation in vitro.

The distribution of intermediate filament (IF) subunits during maturation of skeletal myotubes in vitro was examined by immunofluorescence, using antibodies against two different types of chick IF subunits: (a) 58-kdalton subunits of fibroblasts (anti-58K), and (b) 55-kdalton subunits of smooth muscle (anti-55K). Anti-58K bound to a filament network in replicating presumptive myoblasts and fibroblasts, as well as in immature myotubes. The distribution in immature myotubes was in longitudinal filaments throughout the cytoplasm. With maturation, staining of myotubes by anti-58K diminished and eventually disappeared. Anti-55K selectively stained myotubes, and the fluorescence localization underwent a drastic change in distribution with maturation--from dense, longitudinal filaments in immature myotubes to a cross-striated distribution in mature myotubes that was associated with the I--Z region of myofibrils. However, the emergence of a cross-striated anti-55K pattern did not coincide temperally with the emergence of striated myofibrils, but occurred over a period of days thereafter.

Animals↗
PubMed1979

Prinzmetal's variant angina associated with subarachnoid hemorrhage: A case report.

Prinzmetal's variant of angina occurred in a 48-year-old man who sustained two attacks of subarachnoid hemorrhage within 10 days. The first anginal pain started at the same time that the second cerebrovascular accident developed, but subsequent anginal episodes were not accompanied by other symptoms or signs that indicated new development of subarachnoid hemorrhage. Twelve days later, when nuchal rigidity was fairly improved, the episodes of chest pain ended. A vasospasm of the large coronary arteries--probably due to the derangement of the autonomic nervous system caused by subarachnoid hemorrhage--was presumed to contribute to the occurrence of the variant angina. Based on this case and on review of the literature, we propose that coronary arterial spasm is one of several causes of the cardiac changes seen in subarachnoid hemorrhage.

Angina Pectoris↗
PubMed1979

Echocardiographic findings in patients with aortitis syndrome.

Echocardiography was performed in 18 patients with the aortitis syndrome and in 20 age-matched normal volunteers. The aortic root dimension, the aortic dimension at the level of the sinotubular ridge, the aortic arch dimension, the left ventricular internal dimension, the left atrial dimension, the interventricular septal thickness, and the left ventricular posterior wall thickness were measured. All measurements, except for the left atrial dimension, were significantly greater in patients with aortitis syndrome than in the control subjects. We concluded (1) that the patients with the aortitis syndrome may have an enlarged or narrowed aorta, a dilated left ventricle and left atrium, and a thickened interventricular septum and left ventricular posterior wall; (2) that the incidence and the degree of these abnormalities depend on the presence of complications such as aortic regurgitation and arterial hypertension; and (3) that M-mode as well a cross-sectional echocardiography plays an important role in the assessment of the aorta and heart in the aortitis syndrome.

Adolescent↗
PubMed1978

Sympathetically induced atrial tachycardia. Successful treatment by left stellate ganglion block.

An unusual type of atrial tachycardia was observed in a 52-year-old woman. The tachycardia occurred only when the patient kept the left upper limb in the lateral and horizontal position. Propranolol, atropine sulfate, carotid sinus massage and ocular compression were not effective in terminating or preventing the arrhythmia. Left stellate ganglion block has stopped the tachycardia for at least two years. The atrial tachycardia in this patient was thought to be caused by mechanical stimulation of the left stellate ganglion resulting in pacemaker shifting, as has been demonstrated in the canine heart.

Action Potentials↗
PubMed1978

Biochemical and immunological heterogeneity of 100 A filament subunits from different chick cell types.

The 100 A filament subunit proteins of chick fibroblasts and gizzard smooth muscle were compared. These proteins are major cellular components in these cell types, constituting up to 98% of the cell's total protein. Co-electrophoresis of cytoskeletal fractions of fibroblasts and smooth muscle revealed that the subunit proteins differed in their molecular weights: 58,000 daltons in fibroblasts and 55,000 daltons in smooth muscle. Cytoskeletal fractions from other cell types were also examined: chondroblasts contained the 58,000 dalton subunit, and cytoskeletons of skeletal muscle and cardiac muscle contained both 55,000 and 58,000 dalton proteins. Chick skin and rat kangaroo Pt K2 cells had more complex subunit patterns which resemble prekeratin. The peptide patterns resulting from proteolytic digestion of the 58,000 dalton protein of fibroblasts, the 55,000 dalton proteins of smooth muscle and PT K2 cells, and chick brain tubulin differed from one another. Two-dimensional electrophoresis of reconstituted gizzard smooth muscle 100 A filaments showed the 55,000 dalton subunit to be composed of two major components, differing in their isoelectric points. Antibodies prepared against electrophoretically purified 55,000 dalton subunit protein reacted in immunodiffusion against the original smooth muscle antigen and cytoskeletal fractions from skeletal and cardiac muscle, but not from fibroblasts, brain, liver, or skin cells. A specific antigenic determinant common to subunit proteins in smooth, skeletal, and cardiac muscle, is therefore indicated. A previously described antibody against fibroblast subunit protein reacted weakly against smooth muscle filament protein in immunodiffusion revealing the presence of a common antigenic determinant between the two subunit proteins. These data demonstrate striking antigenic and primary structural differences in 100 A filament subunits from even such closely related cell types as fibroblasts on the one hand and muscle cells on the other.

Animals↗
PubMed1978

Renal net glucose release in vivo and its contribution to blood glucose in rats.

This study describes the contribution of de novo glucose synthesis by the kidney to blood glucose homeostasis in rats. The net glucose release by the kidney in vivo was measured by an isotope-dilution method, which calculated the extent of dilution of injected [(14)C]glucose by glucose newly synthesized in the kidney. The extent of dilution was determined from the difference between the decrease of the actual blood glucose concentration and that of the radioactivity of [(14)C]glucose, after injecting [(14)C]glucose into functionally hepatectomized rats. The results indicate that the net glucose release by the kidney in vivo in normal fed rats was 0.75+/-0.13 mg/dl per min, and that its contribution to blood glucose was 25.9+/-5.0%. When unilateral nephrectomy was performed, under the same conditions, renal net glucose release was one-half of that in rats with two intact kidneys, which indicates the quantitative accuracy of the isotope-dilution method employed in this study. In rats starved for 24 h, the renal net glucose release increased to 0.99+/-0.08 mg/dl per min. Diabetic rats showed a remarkably higher renal net glucose of 2.28+/-0.33 mg/dl per min, which was 360% of the normal level. Treatment of diabetic rats with insulin, restored the renal net glucose release to the normal level. In acidotic rats, renal net glucose release was as great as 1.03+/-0.15 mg/dl per min, which suggests that the acid-base balance participates in control of renal glucose output. Measurements every 6 h throughout the day showed that glucose was supplied from the kidney at a constant rate without any circadian rhythm. These data suggest that renal gluconeogenesis is of physiological importance in the maintenance of homeostasis of blood glucose.

Acidosis↗
PubMed1977

Actin-like filaments in the myoid cell of the testis.

Microfilaments in the myoid cells of the peritubular tissue in the mouse, swine and human testis bind heavy meromyosin (HMM) and form arrowhead complexes. The periodicity of the arrowhead complexes is about 35 nm. Individual filaments show arrowheads that point in the same direction. Opposing polarity of the HMM-bound filaments is also observed. The microfilaments do not bind HMM in the presence of 10 mM ATP. After treatment with the contraction medium of Hoffmann-Berling, the filaments appear to be undulated. These observations indicate that the microfilaments in the myoid cell are actin-like in nature. A small number of thicker filaments (about 10 nm in diameter) which do not bind HMM is also observed in the cell. Microfibrils which have been reported around the human myoid cell are also found in the swine.

Actins↗
PubMed1976

Actin-like filaments in the Sertoli cell junctional specializations in the swine and mouse testis.

Microfilaments at the junctional specializations between adjacent Sertoli cells and between the Sertoli cell and the late spermatid of the mouse and swine testes bind HMM and form arrowhead complexes with a periodicity of about 35 nm. The arrowhead formation is inhibited when the tissues are treated with HMM in the presence of ATP. These observations show that the microfilaments are actin-like in nature. The functional significance of these filaments in the Sertoli cell is discussed.

Actins↗
PubMed1976

Cardiac involvement in the Kugelbert-Welander syndrome.

Two cases of the Kugelberg-Welander syndrome (juvenile form of progressive spinal muscular atrophy) associated with cardiomyopathy and cardiomegaly are presented. The first patient, a 24 year old man, had atrial flutter with complete atrioventricular (A-V) block due to A-H block. Echocardiography revealed an increase in the left atrial and right ventricular dimensions. The second patient was a 26 year old man whose electrocardiogram revealed an A-V junctional rhythm, deep Q wave in leads I, aVL and V5 to V6 and an RS pattern in lead V1. Histologic examination of the myocardium in Case 2 showed slight interstitial fibrosis. Review of previously reported cases shows that (1) the atrium, the ventricular myocardium and A-V conducting tissue may be involved, and (2) atrial arrhythmias, A-V conduction disturbances and congestive heart failure may occur in the Kugelberg-Welander syndrome.

Adult↗
PubMed1976

Tachycardia- and bradycardia-dependent left bundle branch block associated with first degree a-v block. A study using his bundle electrogram during carotid sinus compression.

His bundle electrographic examination was performed during carotid sinus compression as well as atrial pacing in a patient who exhibited intermittent left bundle branch block (LBBB) and first degree A-V block. LBBB was observed at the corrected RR intervals below 920 msec and above 1600 msec. The QRS complexes showed normal intraventricular conduction between these 2 values. The critical cycle lengths could not be determined when ordinary RR intervals were used. The HQ interval remained constant at 70 msec regardless of the pattern of intraventricular condution. It was demonsrated that the patient had both tachycardia- and bradycardia-dependent LBBB with first degree A-V block due to HV block. The authors believe this to be the first case of tachycardia- and bradycardia-dependent bundle branch block studied by His bundle electrography. The important role of His bundle recordings and carotid sinus compression in the diagnosis of rate dependent intraventricular conduction disturbance was stressed and possible mechanisms underlying this rare condition were discussed.

Bradycardia↗
PubMed1975

Ultrastructural study of crystalloids in sertoli cells of the normal, intersex and experimental cryptorchid swine.

Spindle- or needle-shaped crystalloids are observed in Sertoli cells of the intersex and experimental cryptorchid swine in the light and electron microscopes. Small crystalloids are also observed in Sertoli cells of the normal swine only by electron microscopy. These crystalloids consist of fine filaments. The filaments are about 5 nm in diameter and arranged parallel to the long axis of the drystalloid. In cross sections of the crystalloid, the close backing of the filaments shows hexagonal arrays. The interfilamentous distance is about 5 nm. In all animals, bundles of short filaments, which are 5nm in diameter, are observed in the basal part of the Sertoli cells. Ultrastructural similarities among the crystalloids, the bundles of fine filaments, and the filamentous layer in the junctional specialization of the Sertoli cell are shown. These morphological similarities suggest that the crystalloids are formed by the aggregation of the bundles in the Sertoli cells of azoospermic testes.

Animals↗
PubMed1975

Paroxysmal hypertension in aortitis syndrome.

Three patients with aortitis syndrome ehibited paroxysmal hypertension which seemed to result from baroreceptor dysfunction. All of the patients had signs of active inflammation of aortitis syndrome and stenotic carotid and subclavian arteries. During the attacks, the blood pressure rose to at least 230 mm. Hg systolic and the heart rate exceeded 100. However, with prolonged administration of steroid hormones, the attacks ceased. In two patients with dilated thoracic aortas and aortic regurgitation, the attacks of paroxysmal hypertension occurred without apparent precipitating factors and were followed by anginal pain with marked ST depression. The sympathicotonic state resulting from the disturbance of the baroreceptors was considered to be responsible for the attacks. In another patient, the attacks occurred in the course of treatment with a steroid hormone and were provoked only by voluntary micturition. This post-micturition hypertension was presumed to be an expression of abnormal overshooting following a fall in blood pressure after voiding.

Adult↗