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Biomedical subjects

M Ohno

Publications and source records attributed to M Ohno.

At least 613 records · Page 34Linked to original sources
PubMed1982

Location and vestibular responses of interstitial and midbrain reticular neurons that project to the vestibular nuclei in the cat.

Experiments were performed on cats anesthetized with alpha chloralose to locate neurons in and around the interstitial nucleus of Cajal (INC) that project to the vestibular nuclei, and to study labyrinthine inputs to these neurons. Neurons that project to the vestibular nuclei were identified by microstimulation confined to the vestibular nuclei on both sides. All neurons thus identified were activated antidromically from the ipsilateral (but not contralateral) vestibular nuclei. Vestibular projecting neurons were found in the INC and the reticular formation rostral, dorsal and caudal to the INC. About 23% of these neurons were vestibular branching spinal projecting neurons. The median conduction velocity of vestibular projecting neurons was estimated to be in the neighborhood of 12-16 m/s. Stimulation of the contralateral vestibular nerve evoked firing in 29% of neurons projecting to the vestibular nuclei, but not to the spinal cord. Interstitial neurons responded more frequently than reticular neurons (45% vs 11% chi 2 test, p less than 0.001). By stimulation of individual semicircular canal nerves, it was shown that vestibular projecting neurons receive excitation from the contralateral vertical canals, but do not receive substantial inputs from the horizontal canal. Stimulation of the ipsilateral vestibular nerve excited 10% of neurons; suppression of activity was observed for six cells and four of the six were excited by stimulation of the contralateral vestibular nerve. Stimulation of ipsilateral individual semicircular canal nerve did not excite any cells tested; the activity of a few cells was suppressed by stimulation of the vertical canal nerves. One neuron received excitation from the contralateral anterior canal and suppression from the ipsilateral posterior canal. Vestibular branching spinal projecting neurons rarely received labyrinthine inputs as already reported (Fukushima et al. 1980a). These results suggested that vestibular projecting neurons may be involved in vertical vestibular reflexes.U

Action Potentials↗
PubMed1982

A case report on disequilibrium hypercalcemia in hyperthyroidism. Comparison of calcium metabolism with other patients with hyperthyroidism.

The patient, a 30-year-old woman, was admitted to Itoh Hospital in February, 1979 for hyperthyroidism. She had a history of pyelonephritis and recurrent urinary tract infection. Laboratory data on admission revealed overt hyperthyroidism (T3: 405 ng/dl, T4: 22.5 micrograms/dl and T3U: 57.--%), severe hypercalcemia of 12.6 mg/dl and hypercalciuria. The PSP excretion and GFR were both decreased. Serum c-PTH was nondetectable. As the thyroid function improved, there was a gradual decrease and later normalization of plasma calcium, phosphate and urinary calcium excretion. When subtotal thyroidectomy was performed on October 19, 1979, hypertrophy of the parathyroid gland was not demonstrated. In comparison with 98 other hyperthyroid patients, the pathogenesis of hypercalcemia was discussed. In conclusion, hypercalcemia in the patient, T. Y., was regarded as a kind of disequilibrium hypercalcemia which resulted from a combination of increased bone turnover and decreased calcium excretion by the kidney.

Adult↗
PubMed1982

Inhibition of phenylalanine hydroxylase, a pterin-requiring monooxygenase, by oudenone and its derivatives.

Phenylalanine hydroxylase was shown to be inhibited by oudenone and its derivatives in vitro. At a concentration of 2.3 x 10(-3) M, oudenone inhibited phenylalanine hydroxylase by 50%, and some of the oudenone derivatives showed more potent inhibition. The kinetic data have shown that the inhibition by oudenone is competitive with a tetrahydropterin cofactor (6,7-dimethyltetrahydropterin, DMPH4) and noncompetitive with phenylalanine and oxygen. Among 12 oudenone derivatives, there was no parallel structure-activity relationship between the inhibitory effect for phenylalanine hydroxylase and that for tyrosine hydroxylase. A derivative of oudenone, [compound No. 142; 2-(3,4-dihydroxyphenyl)-1-oxopropyl)cyclohexan-1,3-dione] showed the most potent inhibition among the oudenone derivatives. It inhibited phenylalanine hydroxylase by 50% at a concentration of 1.8 x 10(-5) M. This inhibition was a mixed type with either a tetrahydropterin cofactor, DMPH4, or with the substrate phenylalanine, which was different from the inhibition by oudenone. However, the same noncompetitive inhibition was shown toward oxygen.

Cyclopentanes↗
PubMed1981

Effects of stimulation of frontal cortex, superior colliculus, and neck muscle afferents on interstitiospinal neurons in the cat.

Interstitiospinal neurons were activated by antidromic stimulation of the spinal cord ventromedial funiculus at C1 and C4 in cerebellectomized cats under chloralose anesthesia. Neurons responding only to C1 were classified as N cells and those responding both to C1 and C4 were classified as D cells, as in previous experiments (Fukushima et al. 1980a). Vestibular branching interstitiospinal and reticulospinal neurons were also identified as in the previous experiments. Stimulation of the ipsilateral pericruciate cortex evoked firing in 31% of N cells, 41% of D cells and 35% of the vestibular branching neurons, while stimulation of the contralateral cortex excited 6% of N cells, 29% of D cells and 14% of vestibular branching neurons. Response latencies ranged from 2 to 15 ms after the effective pulse. By measuring the thresholds of activation of these neurons while changing the depth of the stimulating electrodes, and by mapping the cortical areas, it was shown that the lowest threshold areas were in the frontal eye fields and the anterior sigmoid gyrus near the presylvian sulcus (Area 6). Stimulation of the latter area often evoked neck or shoulder muscles contraction. Stimulation in the deep layers of the ipsilateral superior colliculus evoked firing in about 20% of interstitiospinal neurons and about 42% of vestibular branching neurons, with typical latencies 2-3 ms after the effective pulse, while stimulation of the contralateral superior colliculus was rarely effective. N cells and D cells responded similarly. Thresholds for activation were high in the intermediate tectal layers and declined as the electrodes entered the underlying tegmentum. This suggests that the superior colliculus is not the main source of synaptic inputs to these neurons. Low threshold points were found above the deep fiber layer when stimulating electrodes were inserted into the pretectum. Stimulation of the C2 biventer cervicis nerve excited about 8% of N cells, 18% of D cells, and 15% of vestibular branching neurons bilaterally with typical latencies around 10 ms. Similar results were obtained when C2 splenius nerves were stimulated. The fibers responsible for such excitation are probably group II, since stimuli stronger than 1.8 times threshold of the lowest threshold fibers were needed to evoke excitation. Response decrement was often observed when stimuli were repeated at 1/s, while no such decrement was observed at the rate of 1/3 s. When the convergence of cortical and labyrinthine excitatory inputs was studied, 36% of interstitiospinal neurons received single inputs either from the pericruciate cortex or from the labyrinth, 22% of neurons received convergent excitation from both and the remaining 42% did not respond to either stimulus. Although vestibular branching neurons rarely received labyrinthine inputs, they frequently showed convergence of excitation to stimulation of the frontal cortex, superior colliculus and vestibular nuclei.

Afferent Pathways↗
PubMed1981

Responses of cat mesencephalic reticulospinal neurons to stimulation of superior colliculus, pericruciate cortex, and neck muscle afferents.

Neurons were recorded extracellularly in the mesencephalic reticular formation outside the interstitial nucleus of Cajal in cerebellectomized cats anesthetized with alpha chloralose. Reticulospinal neurones were identified by antidromic stimulation of the upper cervical segments. Stimulation in the deep layers of the ipsilateral superior colliculus evoked firing in 36% of reticulospinal neurons. For many neurons thresholds for activation were high in the intermediate tectal layers and declined as the electrodes entered the underlying tegmentum. However, low threshold points were found above the deep fiber layer within the superior colliculus for some cells. Stimulation of the contralateral superior colliculus excited 10% of neurons and thresholds for activation were high above the deep fiber layer for all neurons. Stimulation of the ipsilateral and contralateral pericruciate cortex excited 39 and 21% of neurons, respectively. The lowest threshold area was found in the frontal eye fields. Sixteen percent of neurons received excitation from neck muscle afferents (C2 biventer-cervicis) bilaterally. Comparison of responses between mesencephalic reticulospinal neurons and interstitiospinal neurons (Fukushima et al. 1981) showed that responses of the two groups of neurons were similar when the pericruciate cortex and neck muscle afferents were stimulated. However, a difference was observed in tectal responses. since low threshold points were rarely observed above the deep fiber layer for interstitiospinal neurons.

Afferent Pathways↗
PubMed1981

Cleavage of Trimeresurus flavoviridis phospholipase A2 with cyanogen bromide: sequence of the short peptide fragment and formation of a noncovalently bonded complex from the fragments.

Phospholipase A2 from the venom of Trimeresurus flavoviridis (Habu snake) on treatment with cyanogen bromide is split into less than Glu-Gly-Leu-Trp-Gln-Phe-Asn-Hse greater than, which is derived from the N-terminal moiety and is designated as S-peptide, and the remaining large peptide, which is designated as L-peptide. It should be stressed that the N-terminal residue is pyroglutamyl, unlike other phospholipases A2. The L-peptide alone was about 6% as active as the parent molecule. It occurs in dimeric form, like the parent molecule. When L-peptide was mixed with increasing amounts of S-peptide, the activity increased in a hyperbolic manner, indicating the formation of an ordered complex between L-peptide and S-peptide. The dissociation constant of the complex was 2.1 x 10(-7) M and its specific activity was 2.8 times that of L-peptide.

Amino Acid Sequence↗
PubMed1981

Effects of injury to the right ventricular conducting tissue of canine hearts on epicardial activation sequence and electrocardiograms.

The distal right ventricular conducting tissues of 45 canine hearts were experimentally interrupted in various degrees by a transmural incision of the right ventricular free wall, a trans-section of the lateral branches of the right bundle or by injury to the endocardial Purkinje network. Right ventriculotomy caused a slight activation delay (less than 10 msec) of the right ventricle which was restricted to the distal area from the incision, but the delay was not long enough to cause a significant prolongation of the QRS duration in the limb lead ECG. In one experiment, a vertical incision in the middle region induced an exceptional, marked alteration of the right ventricular activation sequence and an apparent prolongation of the QRS duration (16 msec) indicating an incomplete RBBB. However, anatomical analysis revealed that the lateral branches were nearly completely interrupted by the incision. An extensive injury to the Purkinje network extending toward the right ventricular outflow tract by a blunt scalpel caused a local activation delay in the outflow tract, without producing any serious delay resulting in an ECG pattern of RBBB. These results may suggest that right ventriculotomy would induce the RBBB pattern of ECG if lateral branches are extensively injured by the surgical procedure, and that the injury to the Purkinje network extending toward the outflow tract does not play a primary role of genesis of RBBB pattern in ECG.

Action Potentials↗
PubMed1981

Body surface isopotential maps of experimentally induced transient right bundle branch block.

The characteristic patterns of the epicardial activation and body surface isopotential maps (MAPs) were examined in experimental transient right bundle branch block (RBBB) produced by pressing the main stem of right bundle mechanically. During the recovery from the complete block, various degrees of incomplete RBBB (IRBBB) were obtained. The epicardial activation of IRBBB spread in almost normal fashion with delayed right ventricular epicardial breakthrough. And the MAPs manifested intermediate patterns between those obtained in control and in complete RBBB (CRBBB). The MAP patterns of IRBBB were classified into the following 3 groups by the difference of the localized bend of isopotential lines reflecting the epicardial breakthrough. In the advanced IRBBB with QRS prolongation over 25%, the epicardial breakthrough of the left ventricle was detected on the MAPs. In the moderate IRBBB with QRS prolongation around 20%, in addition to the left ventricular breakthrough the right ventricular breakthrough was detected at the center of the anterior chest. In the mild IRBBB with QRS prolongation less than 15%, only the right ventricular breakthrough was detected. These findings indicate usefulness of MAPs for diagnosing the severity of IRBBB due to the damage to the main right bundle. Moreover, these MAP patterns in IRBBB of main right bundle can be distinctly differentiated from the IRBBB MAPs resulting from incisional interruption of lateral branches of right bundle. The present findings also suggest the usefulness of MAPs in diagnosing the site of the conduction disturbance resulting in IRBBB.

Animals↗
PubMed1981

Experimental appraisal for diagnosis of right bundle branch block using the body surface isopotential maps.

This study was designed to detect reflection of epicardial breakthrough to body surface isopotential maps by recording epicardial and body surface maps simultaneously, and to estimate changes in epicardial breakthrough associated with complete and incomplete blocks induced by compression of the main stem of the right bundle branch of trans-sectioning of the lateral branches. In the control, epicardial breakthrough appearing on the right ventricular surface was well detected on the body surface maps as a bend of isopotential lines localized at the mid sternum at 11.5 +/- 1.6 msec (n = 5) after QRS initiation. At complete block immediately after compression of the main stem, the localized bend shifted inferiorly to the left at 17.8 +/- 1.8 msec (n = 5) after QRS initiation, suggesting appearance of the left ventricular epicardial breakthrough. With progression of recovery from the compression, in addition to epicardial breakthrough on the left ventricle, the breakthrough on the right ventricle became detectable again with a delay of 5 msec, and then the former was faded away as time progressed. After trans-sectioning of the lateral branches, sequential changes in the body surface maps were almost the same as in complete block of the main stem but they lapsed about 43 msec (n = 5) shorter in comparison with the complete block. In conclusion, detection of the localized bend of the isopotential lines on the body surface can provide diagnosis of the site and degree of the right bundle branch block in detail.

Animals↗
PubMed1981

Chirally selective synthesis of sugar moiety of nucleosides by chemicoenzymatic approach: L- and D-riboses, showdomycin, and cordycepin.

The symmetric dimethyl esters derived from furan and dimethyl acetylenedicarboxylate was efficiently hydrolysed with pig liver esterase to yield half esters with high optical purity. Following chemical transformations afforded precursors with L-configuration, and chirality transfer through ester exchange was achieved to afford precursors with D-configuration of the sugar moiety of nucleosides. Thus, an efficient approach to L- and D-riboses, showdomycin, and cordycepin (3'-deoxy-adenosine) has been demonstrated.U

Animals↗
PubMed1981

[Studies on the immune state evaluated by various skin antigens in patients with cervical cancer (author's transl)].

Cutaneous delayed hypersensitivity (CDH) tests, using 6 antigens (PHA, PPD, SK-SD, Candida, Mumps and DNCB) were performed in 260 patients with cervical cancer and the following results were obtained. 1) Decrease in incidence of positive CDH (PHA, PPD and DNCB) was found as the clinical stage advanced. Especially, decrease in incidence of positive CDH (DNCB and PHA) was found in stage III and IV. 2) There was no relationship between the incidence of positive CDH (SK-SD, Candida and Mumps) and clinical stage but, decrease in incidence of these tests was found in stage III and IV. 3) In comparison on numbers of positive CDH, there was no significance in control groups and cervical cancer patients. 4) Incidence of advanced invasion of primary lesion (gamma and delta type) was 83.7% in DNCB-negative group who were treated with curative operation. 5) Incidence of regional lymph node metastasis was 42.9% in Candida-negative group, whereas, 16.2% in Candida-positive group who were treated with curative operation.

Antigens↗
PubMed1981

[Regional wall motion of the left ventricle in congestive cardiomyopathy: in comparison with progressive muscular dystrophy of Duchenne type (author's transl)].

The features of regional wall motion abnormalities of the left ventricle were analysed in 11 patients of congestive cardiomyopathy (CCM) in comparison with 22 patients of progressive muscular dystrophy (DMD) of Duchenne type who showed an abnormal motion of the left ventricle by echocardiography. Real time two-dimensional echocardiographic study demonstrated the following results: I) In CCM, (1) only 2 or less of 11 cases preserved a normal motion in each left ventricular segment, and the depression of wall motion of the left ventricle were thought to be generalized; (2) there were 9 cases with segmental wall motion abnormalities and 3 of them demonstrated ventricular aneurysms, and (3) the localizations of the segmental abnormalities varied in each case, and there was no apparent accumulation to any segments. II) In DMD, (1) all the cases showed depressed motions and 8 of them demonstrated a ventricular aneurysm in the posterior wall of the left ventricle (LVPW), (2) while, there was no case showing ventricular aneurysm in the segments other than LVPW, and about one third of all cases showed normal motion in those segments. From these results, we concluded as follows: 1) Although the depression of a wall motion of the left ventricle was generalized in CCM, this was not always uniform and the segmental abnormalities of a wall motion were frequently observed. The localization of the most severely disturbed segment varied in each case. 2) On the other hand, in DMD, the wall motion was disturbed more frequently and more severely in LVPW than in other ventricular segments.

Adolescent↗