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Biomedical subjects

K Yoshii

Publications and source records attributed to K Yoshii.

At least 91 records · Page 5Linked to original sources
PubMed1993

[Cortisone Acetate Reference Standard (Control 921) of National Institute of Health Sciences].

The raw material of cortisone acetate was tested for the preparation of "Cortisone Acetate Reference Standard (Control 921)". The quality of the raw material was examined and compared with the previous Cortisone Acetate Reference Standard (Control 743). Analytical data obtained were as follows: loss on drying, 0.06%; melting point, 245.9 degrees C (decomposition); optical rotation, [alpha]20D = +215.5 degrees; UV spectrum, lambda max = 239 nm and specific absorbance E 1%1 cm (239 nm) = 393; infrared spectrum, the same as that of the previous Reference Standard (Control 743); thin-layer chromatography, no impurities were detected up to 100 micrograms; high-performance liquid chromatography (HPLC), three impurities were detected; assay, 100.5% by HPLC. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 921).

Chromatography, High Pressure Liquid↗
PubMed1993

[Riboflavin Reference Standard (Control 921) of National Institute of Health Sciences].

The raw material for riboflavin was tested for preparation of the "Riboflavin Reference Standard (Control 921)". Analytical data obtained were as follows: melting point, 283.8 degrees C (decomposition); specific absorbance, E1%1 cm = 852 (267 nm), 275 (373 nm), 325 (446 nm); infrared spectrum, the same as that of JP Riboflavin Reference Standard; optical rotation [alpha]20D = 138.5 degrees; thin-layer chromatography, no impurities were detected up to 6 micrograms; high-performance liquid chromatography, a small amount of 9 impurities were detected; loss on drying, 0.16%; assay, 100.3% by spectrophotometry. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 921).

Chromatography, High Pressure Liquid↗
PubMed1993

[Ergocalciferol Reference Standard (Control 921) of National Institute of Health Sciences].

The raw material for ergocalciferol was tested for preparation of the "Ergocalciferol Reference Standard (Control 921)". Analytical data obtained were as follows: melting point, 118.1 degrees C; UV and infrared spectra, the same as those for the JP Ergocalciferol Reference Standard; specific absorbance, E1%1 cm = 457.5 (265 nm); thin-layer chromatography and high-performance liquid chromatography (HPLC), no impurities were detected; assay, 101.0% by HPLC. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 921).

Chromatography, High Pressure Liquid↗
PubMed1993

[Cholecalciferol Reference Standard (Control 921) of National Institute of Health Sciences].

The raw material for cholecalciferol was tested for preparation of the "Cholecalciferol Reference Standard (Control 921)". Analytical data obtained were as follows: melting point, 89.9 degrees C; UV and infrared spectra, the same as those for JP Cholecalciferol Reference Standard (Control 901), respectively; specific absorbance at 265 nm E1%1 cm = 472.2; optical rotation, [alpha]20D = 107.1 degrees; thin-layer chromatography and high-performance liquid chromatography (HPLC), no impurities were detected; assay, 99.97% by HPLC. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 921).

Cholecalciferol↗
PubMed1991

1H-NMR studies of urine in propionic acidemia and methylmalonic acidemia.

The present study deals with the usefulness of 1H-NMR spectroscopy in the chemical diagnosis of propionic acidemia and methylmalonic acidemia. A Varian VXR-500 spectrometer was used. 1H-NMR spectra of urine from a patient with propionic acidemia show peaks of 3-hydroxy-n-valerate, methylcitrate, propionyl glycine, 3-hydroxy-n-butyrate, lactate, 3-hydroxypropionate, tiglylglycine and hippurate. The assignment was made possible by the use of 2D COSY. The spectra from a patient with methylmalonic acidemia show methylmalonate and glycine. 1H-NMR spectroscopy has the advantages of requiring a short time for analysis, relatively small amounts of urine and no preliminary extraction.

Amino Acid Metabolism, Inborn Errors↗
PubMed1990

Inhibitory effect of a new antibiotic, guanine 7-N-oxide, on the replication of several RNA viruses.

Guanine 7-N-oxide (G-7-Ox) was examined for its antiviral activity against 9 viruses based on plaque reduction, neuraminidase activity reduction, a fluorescent antibody technique or ELISA. The following viruses were included in the tests: influenza, Sendai, simian virus 5 (SV5), respiratory syncytial, western equine encephalitis, Japanese encephalitis, vesicular stomatitis, rabies and polio. G-7-Ox showed broad anti-RNA viral activity against all viruses tested, except for poliovirus. Inhibition of persistent SV5 infection by G-7-Ox indicates that its antiviral activity is independent of cytotoxicity.

Animals↗
PubMed1989

Inward rectifier produced by Xenopus oocytes injected with mRNA extracted from carp olfactory epithelium.

Ionic channels encoded by mRNA extracted from carp olfactory epithelium were investigated by injection into Xenopus laevis oocytes. The oocytes expressed an inward rectifier K+ -channel, as detected under two-electrode voltage clamp conditions. The results were as follows. An inactivating inward current appeared on hyperpolarization and increased with increasing extracellular K+ concentrations. The 0 current potentials plotted as a function of log [K+]0 in the range between 2 to 20 mMK+ fell on a straight line, with a slope of 58 mV per tenfold change in K+ concentration, indicating that the current carrier is K+. Chord conductances reached saturation levels on extreme hyperpolarization. The chord conductances at the saturation levels were 35.7, 22.5, and 13.4 muSec in 20, 10, and 5 mM extracellular K+, respectively. Extracellular application of 0.1 mM Cs+ or 0.1 mM Ba2+ blocked the inward current in 2 mM K+, whereas 1 microM TTX or 0.3 mM Cd2+ did not affect the inward current. Inactivation of the inward currents, which became clear on extreme hyperpolarization, was suppressed with decreasing extracellular Na+ concentration. The present results suggest that carp olfactory epithelium is rich in the inward rectifier and is an excellent source of mRNA for cloning cDNA coding the inward rectifier.

Animals↗
PubMed1989

Cerebellopontine angle lipoma with abnormal bony structures--case report.

A cerebellopontine angle lipoma accompanied by a bony protrusion from the left petrous pyramid was discovered in a 35-year-old female with a 10-year history of vertigo and a 3-year history of left tinnitus. Following subtotal removal of the tumor, the frequency of vertigo increased and she was deaf in the left ear. The symptoms, radiological and pathological features, and surgical management of this rare tumor are discussed.

Adult↗
PubMed1989

[Localization of pancreatic insulinomas by combined radiographic methods].

Seventeen cases with a total of eighteen insulinomas were examined by ultrasonography (US), computed tomography (CT), angiography, percutaneous transhepatic portal and pancreatic venous sampling (PTPS) and intraoperative ultrasonography (IOUS). We discussed about diagnostic accuracy of insulinomas on these diagnostic modalities. Tumor localization was achieved by US in 39%, CT in 72% and angiography in 81%. Although total 15 tumors (83%) can be correctly detected, multiple lesions were not completely ruled out. We recommended the criteria in PTPS as follows: Insulin concentration level above 200 mu U/ml. Or, both of insulin concentration ratio (step-up site/control) above three and elevation of the CPR concentration level on the PTPS. According to these criteria, the accuracy rate was 91%. Overall preoperative diagnostic accuracy was 100%. IOUS allowed us to detect the localization of the tumors completely.

Adenoma, Islet Cell↗
PubMed1989

[A case of unilateral masticatory spasm without hemifacial atrophy].

Masticatory spasm is a rare clinical feature and mostly associated with disorders of general movement. Usually it occurs bilaterally. Unilateral masticatory spasm is mostly associated with facial hemiatrophy. So, unilateral masticatory spasm without facial hemiatrophy is extremely rare. As far as we have investigated, only one case has been reported in the literature. We will report one more case herein, with some discussion on its pathogenesis. Case report A 44-year-old man presented with a 8 month history of slowly progressive recurrent spasm of the left masseter muscle. The spasm was exaggerated by tension and lasted for up to 10 seconds. Several drugs could not reduce the frequency of spasm, but only clonazepam could decrease it slightly. On admission, the spasm lasted usually for 1 or 2 seconds. Except for masticatory spasm, neurological examination comprising trigeminal nerve function, was normal and facial atrophy was not observed. On the contrary, hypertrophy of the left masseter muscle was noted. Needle electromyography (EMG) study revealed synchronized spasm discharges of the ipsilateral masseter, lateral and medial pterygoid muscles. All of other investigations, including CSF analysis, electroencephalography, somatosensory evoked potential, visual evoked potential, CT scan and vertebral angiography, showed normal findings. After all, we could not find any apparent organic lesions which cause masticatory spasm, so surgical treatments were not carried out. He was discharged and now, continues to take clonazepam daily.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Specific binding of lectins with the nucleus of the sea urchin embryo and changes in the lectin affinity of the embryonic chromatin during the course of development.

(1) Embryonic cells of sea urchins were made permeable by treating them with glycerol solution for the purpose of allowing penetration of macromolecules into the cell. With the use of such permeabilized cells, several kinds of fluorescent dye-labeled lectins were introduced into the cell, and it was found that some lectins showed notable affinity with the nucleus as compared with cytoplasmic structures. (2) Isolated chromatin was incubated with several kinds of fluorescent dye-labeled lectins in vitro, and the amount of lectins bound with the chromatin was measured by fluorometry. By means of this method, the lectin-binding capacity of chromatin was estimated and compared at various stages of development. It was found that lectins could be classified into three groups according to the mode of binding with the chromatin: (a) Extent of binding increased notably at the gastrula stage (Con A and RCA-120); (b) extent of binding showed a temporary decrease at the gastrula stage (TTA); and (c) very low level of binding was maintained throughout all stages, and no particular change was observed at any stage of development (WGA, SBA, and UEA-I). (3) These facts seem to suggest that lectin-binding components are contained in sea urchin chromatin, and that drastic changes occur in these components of chromatin at the stage of gastrulation. It was proposed that the lectin-binding components such as proteoglycans and glycoproteins may play regulatory roles in embryonic chromatin at early stages of development.

Age Factors↗
PubMed1988

Transfer impedances between different regions of branched excitable cells.

1. The excitable properties of branched cells were measured using a combination of voltage-clamp and frequency-domain techniques. Point impedance functions from either the soma or growth cone of NG-108 cells were curve fitted with a reduced cable model at different membrane potentials to establish kinetic parameters. 2. Transfer impedance functions between the soma and growth cone were measured and simulated with a morphologically determined model. In these experiments the membrane potential was controlled by a single-electrode voltage clamp thus allowing an estimate of transfer functions for any arbitrary input, such as a single synaptic current for differing degrees of tonic synaptic drive. Furthermore, the integration of different regional inputs was evaluated based on the transfer functions between different locations on an individual cell. 3. The activation of an outward steady-state current leads to resonating impedance functions that were used to evaluate the kinetic properties of ionic channels in different regions of branched excitable cells. For simple branching patterns the point and transfer impedances show lower resonant frequencies for active growth cones compared with active somas. 4. More complex branching patterns showed the unexpected result that the voltage-dependent resonant frequency was higher for the growth cone recording than the soma. The presence of a higher resonant frequency when the growth cone is activated does not require more rapid kinetics of the active potassium conductance, since the time constant of the active conductance can be the same in the growth cone and the soma membrane. 5. In conclusion, the resonant frequencies, as well as all other aspects of the impedance functions, are complicated interactions of the detailed branching patterns and active conductances. In general, these interactions are not predictable from a passive electrotonic analysis, especially when the voltage-dependent conductances are distributed throughout the dendritic tree.

Animals↗
PubMed1988

Effect of subthreshold voltage-dependent conductances on the transfer function of branched excitable cells and the conduction of synaptic potentials.

1. Impulse response functions were determined from complex point impedance and transfer functions from cultured NG-108 cells to simulate the propagation of a synaptic potential in response to the release of transmitter. In general, the flow of synaptic current has a much shorter duration than the normal membrane time constant, thereby making the use of impulse response functions useful approximations to synaptic events. 2. The resonance observed during the activation of the potassium conductance was reflected in the impulse response function as a pronounced damped oscillation. A comparison of the impulse response functions calculated from point impedance and transfer functions showed similar results for current injections in the growth cone. 3. In addition to the resonance effects of the voltage-dependent conductances on transfer and impulse response functions due principally to the activation of conductances for outward currents, transfer functions were measured during the activation of a steady-state negative conductance. Under these conditions the phase function approaches 180 degrees, indicating that the voltage response is out of phase with the current. 4. In the steady state, the effect of a negative conductance is to algebraically add to the positive conductances and generally decrease the absolute conductance unless there is a net negative current. The decreased conductance enhances the impulse response and the DC space constant, thus leading to a better propagation of slow potentials. This effect can be seen as a decrease in the electrotonic length, L, with intermediate depolarizations. At large depolarizations the steady-state activation of the K conductance generally dominates and leads to a greatly increased electrotonic length. 5. Both the net conductances and the associated kinetics play a role in shaping the potential changes during a synaptic current. This is especially critical if there is a net negative steady-state conductance. Under these conditions there is a surprising reduction in the impulse response function. 6. Thus, during a subthreshold activation of the voltage-dependent negative conductances, the observable synaptic potentials would be either large potential responses due to an apparent increase in the impedance (algebraic summation of positive and negative conductances with a net positive conductance) or a minimal response because of the phasic cancellation due to a net negative conductance. The latter condition could exist near the synaptic reversal potential due to a large synaptic drive and would appear experimentally as a form of inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Expression of mouse-Torpedo acetylcholine receptor subunit chimeras and hybrids in Xenopus oocytes.

In this study, in vitro synthesized mRNA encoding mouse and Torpedo nicotinic acetylcholine receptor subunits was injected into Xenopus oocytes, followed by assays for assembly onto the oocyte surface (using [125I]alpha-bungarotoxin binding) and for acetylcholine-induced conductances (using voltage clamp). We constructed hybrid acetylcholine receptors in Xenopus oocytes by injecting all 8 possible combinations of 4 subunit-specific mRNAs in which a single subunit is derived from the other species. For each hybrid combination, there is detectable assembly and conductance. We also constructed cDNA clones that encode chimeric acetylcholine receptor subunits in which part of the gamma subunit from Torpedo was replaced by the homologous region of the delta subunit from mouse. None of the chimeric subunits was able to replace the Torpedo gamma, mouse delta, or Torpedo delta subunit with regard to assembly or function. We therefore conclude that widely spaced (and unknown) parts of the protein chain are required for the intersubunit interactions that eventually lead to functional assembly of the receptor.

Animals↗
PubMed1987

Equilibrium properties of mouse-Torpedo acetylcholine receptor hybrids expressed in Xenopus oocytes.

This study used messenger RNA encoding each subunit (alpha, beta, gamma and delta) of the nicotinic acetylcholine (ACh) receptor from mouse BC3H-1 cells and from Torpedo electric organ. The mRNA was synthesized in vitro by transcription with SP6 polymerase from cDNA clones. All 16 possible combinations that include one mRNA for each of alpha, beta, gamma, and delta were injected into oocytes. After allowing 2-3 d for translation and assembly, we assayed each oocyte for (a) receptor assembly, measured by the binding of [125I]alpha-bungarotoxin to the oocyte surface, and (b) ACh-induced conductance, measured under voltage clamp at various membrane potentials. All combinations yielded detectable assembly (30-fold range among different combinations) and ACh-induced conductances (greater than 1,000-fold range at 1 microM). On double-logarithmic coordinates, the dose-response relations all had a slope near 2 for low concentrations of ACh. Data were corrected for variations in efficiency of translation among identically injected oocytes by expressing ACh-induced conductance per femtomole of alpha-bungarotoxin-binding sites. Five combinations were tested for d-tubocurarine inhibition by the dose-ratio method; the apparent dissociation constant ranged from 0.08 to 0.27 microM. Matched responses and geometric means are used for describing the effects of changing a particular subunit (mouse vs. Torpedo) while maintaining the identity of the other subunits. A dramatic subunit-specific effect is that of the beta subunit on voltage sensitivity of the response: gACh(-90 mV)/gACh(+30 mV) is always at least 1, but this ratio increases by an average of 3.5-fold if beta M replaces beta T. Also, combinations including gamma T or delta M usually produce greater receptor assembly than combinations including the homologous subunit from the other species. Finally, EACh is defined as the concentration of ACh inducing 1 microS/fmol at -60 mV; EACh is consistently lower for alpha M. We conclude that receptor assembly, voltage sensitivity, and EACh are governed by different properties.

Animals↗
PubMed1987

[Causative factors of recurrence of chronic subdural hematoma].

Burr hole opening and irrigation of hematoma is now a widespread simple technique for the treatment of chronic subdural hematoma (CSH). However, recurrence of hematoma has been sometimes experienced after initial treatment. The purpose of this report is to analyze the causative factors in recurrence of the hematoma after the burr hole opening and irrigation. Out of 68 adult cases of CSH treated by burr hole opening and irrigation technique at Toranomon Hospital during the past nine years, 11 cases (16.2%) showed recurrence of symptoms due to reaccumulation of hematoma after the 1st operation. They were compared with non-recurrence cases from the viewpoint of clinical signs, symptoms and course and serial CT findings. But there was no statistically significant difference between them. The causative factors of recurrence of CSH were analyzed and divided into four categories. Type 1 (3 cases): specific promoting factors--Primary intracranial hypotension (2 cases) and anticoagulant therapy (1 case). Type 2 (1 cases): immature timing of operation. Type 3 (4 cases): other causes probably due to operative procedure--Insufficient postoperative external drainage. Type 4 (3 cases): unknown cause. Several authors have reported causative factors of recurrence of CSH so far, but they are still controversial. An additive treatment in the cases involving specific factors, and planning the timing and some procedures of operation are proposed in order to avoid recurrence of CSH.

Adult↗
PubMed1987

Primary repair of interrupted aortic arch and severe aortic stenosis in neonates.

Two infants, aged 36 days old (Case 1) and 18 days old (Case 2) with interrupted aortic arch types B and A, respectively, and with severe aortic stenosis, were successfully operated on by use of pulsatile cardiopulmonary bypass. The great arteries were normally related in Case 1 and were transposed in Case 2. Repair involved the following procedure: ligation of the patent ductus arteriosus, restoration of aortic continuity with an 8 mm polytetrafluoroethylene graft, placement of an internal patch to tunnel all left ventricular blood from the left ventricle through the ventricular septal defect into the pulmonary artery in Case 1 and patch closure of the ventricular septal defect in Case 2, transection of the main pulmonary artery, anastomosis between the proximal pulmonary artery and the ascending aorta, and interposition of a valved conduit between the right ventricle and the distal pulmonary artery. The operative field could be approached easily through a median sternotomy. Postoperative cardiac catheterization revealed satisfactory anatomical and hemodynamic results in both cases.

Aorta↗