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Biomedical subjects

T Yoshihara

Publications and source records attributed to T Yoshihara.

At least 127 records · Page 7Linked to original sources
PubMed1993

Ultrastructure of nerve endings in the stapedius muscle of the squirrel monkey.

The stapedius muscle of the squirrel monkey (Saimiri sciureus) was studied electron microscopically with regard to neuromuscular junctions, muscle-tendon junctions and tendons. Two types of neuromuscular junctions were identified. The first type which was predominant in number showed well-developed primary and secondary synaptic clefts. They were almost the same with those of other mammalian skeletal muscles. The second type showed a flat-shaped junction with fewer secondary synaptic clefts. Muscle-tendon junctions were characterized by many interdigitations between the muscle fibers and tendon. The tendon was composed of collagen fibers, approximately 70-100 nm in diameter. Muscle spindles were not present, while nerve endings resembling the Golgi tendon organ were found adjacent to the tendon and the muscle-tendon junctions. These findings suggest that a feedback system may exist and regulate the fine contractile function of this muscle.

Animals↗
PubMed1993

New interpretation of systolic time intervals from active cross-bridge model.

Using an active cross-bridge model proposed by the authors, it has been established theoretically that cross-bridge activation rate (Ka) of the left ventricular myocardium, which might correspond to the rate of binding of Ca2+ with troponin C, is approximately expressed as a simple formula: Ka = 3/electromechanical systole (sec-1), although no definitive biological proof has yet been provided for the equation. One hundred eighteen patients without significant cardiac disease and 6 patients who had atrioventricular block with a permanent pacemaker were evaluated to determine the Ka value of the normal human left ventricular myocardium (test 1), and to examine the effect of changes in heart rate (test 2) as well as afterloading (test 3) or dobutamine infusion (test 4) on Ka. The pacing rate was increased from 50 to 110 beats/min at 20-beat increments in test 2. Arterial pressure was elevated by angiotensin II infusion in test 3, and 7 subjects received a continuous dobutamine infusion in test 4. The Ka value was found to be related to heart rate, to be increased by dobutamine infusion, and to be decreased by myocardial lengthening due to afterloading. Dependence of Ka on heart rate appeared to result from changes in myocardial length. The Ka value corrected for heart rate (Kac) had an average variation of only 4.6%, and was unrelated to age or myocardial length in individual subjects. Thus, the Kac value of normal human left ventricular myocardium appears to be nearly constant between individuals but to be increased by catecholamine infusion or myocardial shortening.

Adult↗
PubMed1993

Pathological analysis of bone fractures in race horses.

Pathomorphological analysis was performed on fractured bones of 470 race horses. The most common fracture site was the limb (98% of cases), and the majority of fractures were intra-articular. Focal osteochondral lesions consisting of osteochondrosis, osteonecrosis and osteosclerosis were observed frequently in fractured and non-fractured bones. In the fractured bones, the lesions frequently appeared in the vicinity of the fractured site. Under the influence of antecedent osteochondrosis from the young stage, osteosclerotic and osteonecrotic lesions may have been induced by immoderate exercise and localized ischemia. These morbid conditions may be important as local predisposing factors for bone fracture because the osteosclerotic and osteonecrotic lesions may contribute to diminished resistance to torsion and shearing forces.

Age Factors↗
PubMed1993

Accelerated idioventricular rhythm in three newborn infants with congenital heart disease.

Accelerated idioventricular rhythm was observed in three newborn infants with congenital heart disease. This ventricular arrhythmia in all of our patients did not alter the clinical features of the congenital heart disease, and it disappeared at the ages of 84 days, 40 days, and 45 days, respectively. This arrhythmia is generally considered to be benign, which also appears to be the case with the newborn infant with congenital heart disease.

Age Factors↗
PubMed1993

Misdirected reinnervation in the feline intrinsic laryngeal muscles after long-term denervation.

Nerve terminals which resembled the autonomic nerve varicosities were found at all neuromuscular junctions of the feline intrinsic laryngeal muscles after 21 months of unilateral laryngeal paralysis. The structure of muscle fibers was preserved throughout this period, although there was no evidence of regeneration of transected recurrent laryngeal nerve. In the cricothyroid muscle, misdirected reinnervation was recognized in the different pathways from the other intrinsic laryngeal muscles.

Animals↗
PubMed1993

Second cutaneous neoplasms after acute lymphoblastic leukemia in childhood.

Two cases of second cutaneous neoplasms, one with adenoid cystic carcinoma of the skin and the other with basal cell carcinoma, both occurring 7 years after treatment for childhood acute lymphoblastic leukemia (ALL) are reported. Although such cutaneous neoplasms are generally reported in patients over 40 years of age, our cases, which were diagnosed at the ages of 9 and 14, are the first report of the occurrence of such cutaneous neoplasms following ALL. The neoplasms arose from the scalp of two patients who had received cranial irradiation for central nervous system prophylaxis. The possible link between leukemia therapy incorporating irradiation and the pathogenesis of second cutaneous neoplasms in the scalp is discussed.

Carcinoma, Adenoid Cystic↗
PubMed1993

Persistent adrenergic reinnervation of previously denervated muscle in cat.

Synapse formation by aberrant nerves at chronically denervated intrinsic laryngeal muscles was observed even at 21 months after the transection of the recurrent laryngeal nerve in cats. Some of the aberrant nerves were adrenergic, and these nerve terminals were in synaptic contact with the postsynaptic membrane of the neuromuscular junctions together with non-adrenergic nerve terminals. Therefore, heterogeneous reinnervation between adrenergic nerve and muscle was found to be maintained for a long time.

Adrenergic Fibers↗
PubMed1993

Establishment and characterization of a human neuroblastoma cell line derived from a brain metastatic lesion.

We encountered a case of abdominal primary stage IV neuroblastoma which recurred in the central nervous system. A neuroblastoma cell line, designated KP-N-NS, was established from this brain metastatic lesion. This is considered to be the first neuroblastoma cell line established from a brain metastatic lesion. In culture, KP-N-NS exhibited N(neuroblastic) type cell morphology with neurite-like processes and small cell bodies. This cell line revealed karyotypic abnormality, 46, XX, -1, +der (1)t(1;?)(p36.1;?), and twelve-fold amplification of MYCN DNA (twice as much in primary bone marrow tumor cells). Integrin study indicated high expression levels of alpha 1 beta 1 and alpha 4 beta 1, but alpha 2 beta 1, alpha 3 beta 1, alpha 5 beta 1, alpha 6 beta 1, alpha 6 beta 4, and alpha v beta 3 were barely detectable by fluorescence-activated cell sorting (FACS) analysis. Compared with 8 other previously established N-type neuroblastoma cell lines, no significantly characteristic integrin expression was detected in this cell line. KP-N-NS will provide a useful tool for the study of metastasis and relapse in the central nervous system in neuroblastoma patients.

Brain Neoplasms↗
PubMed1993

Cloning and characterization of four types of cDNA encoding myeloperoxidase from human monocytic leukemia cell line, SKM-1.

Four cDNA clones encoding myeloperoxidase were isolated from a cDNA library of monocytic leukemia SKM-1 cells. The sequences of two of them were identical to those of cDNA clones previously isolated from a HL-60 cell cDNA library. The sequences of the other two cDNA clones, MP-S34 and MP-S29, differed from those previously described. There was a deletion of 57 bp in the MP-S34 sequence, which was generated by partially skipping exon 9. MP-S29 had a 171 bp deletion, which was generated by completely skipping exon 10. Thus MP-S34 and MP-S29 encoded polypeptides lacking 19 and 57 amino acids, respectively. Both deletions were located on the sequence encoding the heavy subunit. These results indicate that the heterogeneity of the heavy subunit of MPO observed in leukocytes or leukemia could be in part produced by partial or complete skipping of an exon.

Amino Acid Sequence↗
PubMed1992

Unique expression of integrin fibronectin receptors in human neuroblastoma cell lines.

Cultured human neuroblastoma cells can be classified morphologically into 3 types: neuroblastic (N), intermediate (I) and substrate adherent (S). Neuroblastoma cells of all types were found to attach and display distinct morphological characteristics on fibronectin, with S-type cells attaching better than N-type cells. Studies of the expression of integrin fibronectin receptors (alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1 and alpha V beta 1) were carried out using a total of 26 morphologically distinct cell lines and their subpopulations. Fluorescence-activated cell sorting (FACS) analysis and immunoprecipitation revealed that all S-type cells expressed abundant alpha 5 beta 1, while N-type cells barely expressed this molecule. Although alpha 3 beta 1 expression of S-type cells was also higher than that of N-type cells, some N-type cells had significantly increased levels of this molecule. alpha 4 beta 1 was found to be randomly expressed. All cell lines tested expressed alpha V beta 1. Human neuroblastoma cells, the majority of which are N-type cells with very low alpha 5 beta 1 expression, are also contrasted with other childhood cancer cells (rhabdomyosarcoma, Ewing's sarcoma, and glioma), all of which expressed high levels of alpha 5 beta 1. The characteristic expression of integrin fibronectin receptors may account for the clinically unique tumor behavior, and the immunohistochemical staining for integrins may become a useful alternative to conventional histology in differential diagnosis and a marker for prognosis in neuroblastoma.

Cell Adhesion↗
PubMed1992

Malignant fibrous histiocytoma of the auricle: an immunohistochemical and electronmicroscopic study.

Malignant fibrous histiocytoma (MFH) is a soft-tissue tumor of late adult life. This tumor is uncommon in the head and neck region. A case of MFH arising in the auricle is presented with immunohistochemical and electronmicroscopic findings. Histologically the tumor was characterized by numerous spindle cells with abundant eosinophilic cytoplasm and many small capillaries. They were positively stained with vimentin, alpha 1-antitrypsin, and alpha 1-antichymotrypsin. Electronmicroscopically, some tumor cells contained abundant lysosomes and others contained numerous filaments.

Adult↗
PubMed1992

Development of the endolymphatic sac in chick embryos, with reference to the degradation of otoconia.

The endolymphatic sac of chick embryos (from embryonic day 7 to 1-day-old chicks) was studied light- and electron-microscopically. At stage 30-31 (embryonic day 7-7.5), the epithelial cells of the endolymphatic sac were cuboidal to columnar in shape. Microvilli were relatively well developed. The intercellular space was wide. In the endolymphatic space of the endolymphatic sac, varying shapes and sizes of otoconia-like bodies were often observed. Intracytoplasmic phagosomes containing these bodies were rarely found. After stage 37 (embryonic day 11), otoconia-like bodies in the endolymphatic sac decreased in number and size. They were almost the same as the otoconia in the macular organs, ultrastructurally. These findings indicate that the endolymphatic sac of the chick embryos may possess the function of otoconial degradation and removal of calcium from otoconia.

Animals↗
PubMed1992

[The effect of propranolol on the myocardial force-length relationship in the in situ canine left ventricle].

The effect of beta-adrenoceptor blockade on the wall performance of the in situ canine left ventricle (LV) was evaluated based on the LV end-systolic force-diameter (Fes-Des) relation in 10 healthy mongrel dogs. LV diameter was measured with ultrasonic crystals, and LV pressure was measured with a micromanometer. Preload was altered by inferior vena caval (IVC) occlusion. In the control contractility state, the IVC was occluded for 7 sec. Blockade of the cardiac beta-adrenergic nerves was induced with 2 mg/kg propranolol i.v.. Slopes (Ec) and extrapolated diameter intercepts (D(o)) of the LV Fes-Des relation were obtained from end-systolic data of the control contractility state and after the infusion of propranolol. Ec was used as an index for the inotropic state of the myocardium of the LV wall. IVC occlusion during 7 sec under the control contractility state produced little change in the heart rate. Thus, IVC occlusion for 7 sec avoided the major reflex change of autonomic tone. After the infusion of propranolol, the heart rate and Ec both decreased by 24 and 43% of the control value, respectively; whereas, D(o) was not significantly altered. Therefore, it was suspected that the cardiac beta-adrenergic nerve played an important role in maintaining myocardial contractility state of the in situ canine LV wall.

Adrenergic Fibers↗
PubMed1991

2.5S nerve growth factor enhances survival, phagocytosis, and superoxide production of murine neutrophils.

The effect of 2.5S nerve growth factor (NGF) on survival, phagocytosis, and superoxide production of murine neutrophils was examined and compared with the effects of interleukin-3 (IL-3) and recombinant GM colony-stimulating factor (rGM-CSF). NGF enhanced the viability of neutrophils isolated from peripheral blood and peritoneal cavity in a dose-dependent way. IL-3 50 U/mL had no effect. rGM-CSF 50 U/mL had an effect similar to that of 50 ng/mL NGF. NGF also enhanced the phagocytosis of hydrophilic microspheres by peritoneal neutrophils, and the activity of NGF was greater than that of IL-3 or rGM-CSF. NGF enhanced the superoxide production induced by phorbol 12-myristate 13-acetate (PMA), which acts at postreceptor sites, and that induced by opsonized zymosan, a receptor-mediated ligand. The stimulating activity of NGF was largely comparable to that of rGM-CSF. The present data show that NGF bound to neutrophils enhances their survival, phagocytosis, and superoxide production. Thus, we postulate that NGF plays an important role in the inflammatory processes.

Animals↗
PubMed1991

Synapse formation by autonomic nerves in the previously denervated neuromuscular junctions of the feline intrinsic laryngeal muscles.

Nerve terminals of unknown origin at the previously denervated neuromuscular junctions (NMJ) of the feline intrinsic laryngeal muscles were investigated. Until 3 weeks after the transection of the recurrent laryngeal nerve (RLN), no axons were observed in the Büngner's bands and the NMJ, accompanied by a marked decrease of autonomic nerves around the blood vessels. At 5-6 weeks nerve varicosities labeled by 5-hydroxydopamine (5-OHDA) were observed in the Büngner's bands together with an increase of autonomic nerves around the blood vessels. At 9-30 weeks (8 cases) nerve terminals were found at the NMJ in all cases. Even if the ipsilateral vagosympathetic trunk was transected at 17 weeks, nerve terminals were found at all the NMJ 3 weeks after this treatment, indicating that nerve terminals were not from the original RLN. These nerve terminals were considered to be autonomic because nerve terminals labeled by 5-OHDA were observed. Furthermore, in the case of the removal of the superior cervical ganglion (SCG) and the nodose ganglion at 21 weeks, though nerve varicosities were found in the Büngner's bands, nerve terminals were not found 9 days after this treatment, suggesting that the ipsilateral SCG possibly played an important role. In electromyographic findings fibrillation-like activities were recognized in 8/11 cases after 5 weeks. The relationship of this phenomenon to fibrillation and muscle atrophy was discussed.

Animals↗
PubMed1991

Hemophagocytic syndrome associated with aggressive natural killer cell leukemia.

We describe a patient who had aggressive natural killer cell leukemia with profound hemophagocytosis. This combination must be underscored as one of several hemophagocytic syndromes. Activated phagocytes in the bone marrow appeared morphologically normal and could possibly be proliferating in response to some cytokine(s) such as interferon-gamma produced by leukemic cells, whose serum level was found to be extremely elevated in this case.

Adult↗
PubMed1991

Parathyroid gland adenoma in primary hyperparathyroidism: report of two cases--chief and oxyphil cell adenoma.

Parathyroid adenomas are classified into two types: chief cell and oxyphil cell variants. In this report two types of parathyroid adenoma in association with hyperparathyroidism were examined. Both cases had suffered from renal calculi, and underwent operation. The laboratory tests showed high serum calcium and parathyroid hormone (PTH) levels. An exploratory surgery revealed a solitary tumor in each case. After extirpation of the parathyroid tumor these data returned to normal values. Electronmicroscopically, oxyphil cell adenoma in this report was characterized by numerous mitochondria and annulate lamellae in the cytoplasm. In some tumor cells secretory-like granules were observed.

Adenoma↗