Biomedical subjects

H Ichiki

Publications and source records attributed to H Ichiki.

At least 19 recordsLinked to original sources

PubMed2001

N-chlorotaurine, a novel endogenous antimicrobial agent: tolerability testing in a mouse model.

OBJECTIVE: To investigate the tolerability of N-chlorotaurine, a new antimicrobial agent, by application to the middle ear in a mouse model. METHODS: Five BALB/c mice were each injected through the tympanic membrane with 5 microL of 0.1%, 1.0%, and 10% N-chlorotaurine and compared with animals in which 0.9% isotonic sodium chloride solution, 0.2% gentamicin sulfate, and 0.25% trimethyltin chloride were instilled. Auditory brainstem responses to clicks were evaluated repeatedly between 4 and 75 days after injection, and histologic investigations of the inner ear were performed subsequently. Three additional groups of mice were injected with isotonic sodium chloride solution, 1.0% N-chlorotaurine, and 0.25% trimethyltin, and brainstem responses to tone bursts of 8, 16, and 32 kHz were tested. In addition, the middle ear was examined histologically. RESULTS: Mice treated with isotonic sodium chloride solution, 0.1% N-chlorotaurine, and 0.2% gentamicin sulfate did not show changes in response threshold. Treatment with 1.0% and 10% N-chlorotaurine caused a reversible increase in auditory brainstem response threshold by 20 dB 4 days after application because of local irritation around the perforation of the tympanic membrane. In contrast, 0.25% trimethyltin showed a permanent elevation of auditory brainstem response threshold of 10 to 15 dB and a scattered loss of outer hair cells predominantly in the apical turn. No alterations of the inner ear were observed in the other treatment groups. The mucous membrane of the middle ear remained unaffected in all test groups. CONCLUSION: Application of N-chlorotaurine to the middle ear is well tolerated without adverse effects and may be a useful new endogenous antimicrobial agent for local treatment of otologic infections.

Animals↗

PubMed2001

Connexin 26 in human fetal development of the inner ear.

Specialized for intercellular communication, gap junctions have been theorized to provide a means (the epithelial and connective tissue gap junction systems) by which fluid and ions might be transported for maintenance of high levels of endolymphatic K+ [Kikuchi et al., 1994. Acta Otolaryngol. 114, 520-528] in the inner ear. A primary constituent of these gap junctions is connexin 26 (Cx26), a protein encoded by the gene GJB2 and found in both epithelial and connective tissue cells. It has been shown that a mutation in Cx26 accounts for 50% of patients with autosomal recessive nonsyndromic hearing loss. In the present study, we document the emergence and distribution features of Cx26 through various stages (weeks 11-31) of gestation in human, fetal cochleae. Comparative patterns of Cx26 distribution are also presented in the mature rat. The cochleae were fixed in 4% paraformaldehyde within 2 h post mortem. Immunohistochemical studies were performed using a rabbit polyclonal antibody raised against synthetic peptide and corresponding with amino acids 108-122. Specimens were mounted into paraffin sections. Results show that Cx26-like immunoreactivity is evident at a prenatal age of 11 weeks and maintains a high intensity of reactivity through 31 weeks of gestation. The appearance of this reactivity seemed to modulate in parallel with the onset of development and histological maturation as well as provide functional maintenance. In the human fetal cochlea, Cx26-like immunoreactivity distribution resembled adult patterns by fetal week 20. At the completion of morphological development by week 31, reactivity appeared to achieve an adult profile of distribution. Descriptions and discussion of Cx26 distribution patterns are presented in detail.

Adult↗

PubMed2001

Activation of potassium conductance by ophiopogonin-D in acutely dissociated rat paratracheal neurones.

1. The effect of ophiopogonin-D (OP-D), a steroidal glycoside and an active component of Bakumondo-to, a Chinese herbal antitussive, on neurones acutely dissociated from paratracheal ganglia of 2-week-old Wistar rats was investigated using the nystatin-perforated patch recording configuration. 2. Under current-clamp conditions, OP-D (10 microM) hyperpolarized the paratracheal neurones from a resting membrane potential of -65.7 to -73.5 mV. 3. At the concentration of 1 microM and above, OP-D concentration-dependently activated an outward current accompanied by an increase in the membrane conductance under voltage-clamp conditions at a holding potential of -40 mV. 4. The reversal potential of the OP-D-induced current (I(OP-D)) was -79.4 mV, which is close to the K(+) equilibrium potential of -86.4 mV. The changes in the reversal potential for a 10 fold change in extracellular K(+) concentration was 53.1 mV, indicating that the current was carried by K(+). 5. The I(OP-D) was blocked by an extracellular application of 1 mM Ba2+ by 59.0%, but other K(+) channel blockers, including 4-aminopyridine (3 mM), apamin (1 microM), charybdotoxin (0.3 microM), glibenclamide (1 microM), tolbutamide (0.3 mM) and tetraethylammonium (10 mM), did not inhibit the I(OP-D). 6. OP-D also inhibited the ACh- and bradykinin-induced depolarizing responses which were accompanied with firing of action potentials. 7. The results suggest that OP-D may be of benefit in reducing the excitability of airway parasympathetic ganglion neurones and consequently cholinergic control of airway function and further, that the hyperpolarizing effect of OP-D on paratracheal neurones via an activation of K(+) channels might explain a part of mechanisms of the antitussive action of the agent.

Action Potentials↗

PubMed2001

Immunohistochemical and morphological studies on the human fetal cochlea: a comparative view on methods.

The preservation of morphology and antigenicity can vary uncontrollably with human fetuses since these rely heavily on immediate fixation of the temporal bone following spontaneous abortion. Once good fixation is established, there is the question of the approach taken for morphologic and immunohistochemical studies. To achieve maximal preservation for the purpose of studying normal and pathologic fetal cochleae, commonly used preparation methods for analyzing the cochlea were reviewed and compared for both immunohistochemical and morphologic studies. Cochleae obtained after spontaneous abortion ranged from the 9th gestational week to birth. Four different methods were compared for morphologic study: the block surface method; a microslicing technique; paraffin; and celloidin sectioning. For immunohistochemical study, three methods were compared: pre-embedding; paraffin; and frozen sectioning. For morphologic preservation, the block surface method gave best overall results, showing good representation of the fetal cochlea for surface preparation, light, and electron microscopy. Celloidin sectioning was also found to show good light microscopic results for both the middle and inner ear. To achieve optimal results, preservation quality, fixation procedures, and antibody all contribute to the efficacy of a methods choice.

Antibodies↗

PubMed2001

Antidiabetic activity of a xanthone compound, mangiferin.

Mangiferin (MF) isolated from Anemarrhena asphodeloides Bunge rhizome, was tested for antidiabetic activity in KK-Ay mice, an animal model of type-2 diabetes. MF lowered the blood glucose level of KK-Ay mice 3 weeks after oral administration (p < 0.01). However, no effect on the blood glucose level in normal mice was seen, indicating that MF could be useful in treating type-2 diabetes. In addition, MF improved hyperinsulinemia and, on insulin tolerance test, reduced blood glucose levels of KK-Ay mice. From these findings, it seems likely that MF exerts its antidiabetic activity by decreasing insulin resistance.

Administration, Oral↗

PubMed2001

Goldenhar's syndrome: congenital hearing deficit of conductive or sensorineural origin? Temporal bone histopathologic study.

BACKGROUND: Oculoauriculovertebral dysplasia (OAVD) (Goldenhar's syndrome) is a congenital syndrome with ipsilateral deformity of the ear and face, epibulbar lipodermoids, coloboma, and vertebral anomalies. Goldenhar's anomaly has often been associated with a degree of congenital hearing deficits, almost always of a conductive origin, but a sensorineural component is also suspected in some cases, evident through malformations of the inner ear. PATIENTS AND METHODS: Both temporal bones of a 10-day-old deceased patient with oculoauriculovertebral dysplasia were examined by light microscopy. RESULTS: The ear deformities included deformity of the auricle, atresia of the external auditory canal, and malformation of the tympanic cavity and ossicles. Abnormalities of the stria vascularis and the semicircular canals were also demonstrated. Further inner ear deformities were not identified in this case. CONCLUSION: These histopathologic findings appear to confirm the conductive component of the congenital hearing deficit, but a sensorineural component could not be omitted. The ear alterations favor early developmental field defects. The causes of this condition are controversial. Recent results in genetic research pertaining to the MSX class genes permit better understanding of the variety, variability, and different degrees of severity of the anomalies described here.

Goldenhar Syndrome↗

PubMed2001

Purification, characterization, and genetic analysis of Cu-containing dissimilatory nitrite reductase from a denitrifying halophilic archaeon, Haloarcula marismortui.

Cu-containing dissimilatory nitrite reductase (CuNiR) was purified from denitrifying cells of a halophilic archaeon, Haloarcula marismortui. The purified CuNiR appeared blue in the oxidized state, possessing absorption peaks at 600 and 465 nm in the visible region. Electron paramagnetic resonance spectroscopy suggested the presence of type 1 Cu (g(II) = 2.232; A(II) = 4.4 mT) and type 2 Cu centers (g(II) = 2.304; A(II) = 13.3 mT) in the enzyme. The enzyme contained two subunits, whose apparent molecular masses were 46 and 42 kDa, according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N-terminal amino acid sequence analysis indicated that the two subunits were identical, except that the 46-kDa subunit was 16 amino acid residues longer than the 42-kDa subunit in the N-terminal region. A nirK gene encoding the CuNiR was cloned and sequenced, and the deduced amino acid sequence with a residual length of 361 amino acids was homologous (30 to 41%) with bacterial counterparts. Cu-liganding residues His-133, Cys-174, His-182, and Met-187 (for type 1 Cu) and His-138, His-173, and His-332 (for type 2 Cu) were conserved in the enzyme. As generally observed in the halobacterial enzymes, the enzymatic activity of the purified CuNiR was enhanced during increasing salt concentration and reached its maximum in the presence of 2 M NaCl with the value of 960 microM NO(2)(-) x min(-1) x mg(-1).

Absorption↗

PubMed2001

Antidiabetic activity of the rhizoma of Anemarrhena asphodeloides and active components, mangiferin and its glucoside.

The antidiabetic activity of the rhizoma of Anemarrhena asphodeloides was investigated in KK-Ay mice, an animal model of genetic type 2 diabetes. The water extract of the rhizoma (AA) (90 mg/kg) reduced blood glucose levels from 570 +/- 29 to 401 +/- 59 mg/dl 7 h after oral administration (p<0.05) and also tended to reduce serum insulin levels in KK-Ay mice. AA-treated KK-Ay mice had significantly reduced blood glucose levels in an insulin tolerance test. Based on these results, the antidiabetic mechanism of AA may be due to decreased insulin resistance. In addition, the active components of AA were confirmed to be mangiferin and its glucoside.

Animals↗

PubMed2001

The suppressive effect of mangiferin with exercise on blood lipids in type 2 diabetes.

The effect of mangiferin (MF) with exercise on bood lipids was studied in KK-Ay mice, an animal model of type 2 diabetes. MF (30 mg/kg) reduced the blood cholesterol (p<0.05) and triglyceride level (p<0.01) of KK-Ay mice with exercise 2 weeks after oral administration when compared with the control group. Diabetes also often has elevated lipid levels. Therefore, it may be that MF has beneficial effects on hyperlipidemia in type 2 diabetes.

Animals↗

PubMed1998

Delayed recovery of auditory cortical evoked potentials is correlated with cortical neuronal death after transient cerebral ischemia in awake gerbils.

Early detection of irreversible neuronal change after transient cerebral ischemia is important so that adequate treatment can be initiated within the therapeutic window. We have examined the correlation between changes in middle-latency auditory evoked potentials (MAEPs) and histological changes in the auditory cortex of awake Mongolian gerbils subjected to 4 min or 12 min of transient cerebral ischemia. Post-ischemic MAEPs were characterized by the appearance of a markedly large negative and positive component at approximately 17-22 ms latency in both groups. Delay in the appearance of the high amplitude (maximal amplitude at 45 min after recirculation in the 12-min ischemia group) precedes the slowly developing death of neurons in the auditory cortex that results from transient cerebral ischemia.

Animals↗

PubMed1998

New antidiabetic compounds, mangiferin and its glucoside.

Mangiferin (MF) and its glucosides (mangiferin-7-O-beta-glucoside) (MG) isolated from Anemarrhena asphodeloides Bunge rhizome, were tested for their antidiabetic activity in KK-Ay mice, an animal model of non-insulin-dependent diabetes mellitus (NIDDM). MF and MG lowered the blood glucose level of KK-Ay mice after oral administration. However, no affect on the blood glucose level in normal mice was seen, indicating that MF and MG are useful in treating NIDDM. In addition, MF or MG improved hyperinsulinemia in KK-Ay mice. From these findings, it seems likely that MF and MG exert their its antidiabetic activity by increasing insulin sensitivity.

Animals↗

PubMed1998

Delayed recovery of cortical auditory evoked potentials and blood flow precede cortical neuronal death after transient cerebral ischemia in gerbils.

Cortical neurons develop into neuronal death four days after transient cerebral ischemia. The aim of this study is to detect early post-ischemic changes in the cortex that will develop into cortical neuronal death later. The detection is important for starting adequate treatment within the therapeutic window. We have examined changes in middle-latency auditory evoked potentials (MAEPs) and cortical blood flow (CBF) in relation to the histological changes in the auditory cortex of Mongolian gerbils subjected to transient cerebral ischemia. At 2 min after bilateral carotid occlusion, the amplitude of MAEPs and CBF were reduced to 22.2 to 23.4% and 24.3 to 27.4% of the pre-ischemic level, respectively. In the 4-min ischemia group, the amplitude of each parameter recovered rapidly to the pre-ischemic level. In the 12-min ischemia group, the recovery of MAEPs and CBF was delayed by, from 20 to 30 min, and about 10 min, respectively. Also, scattered eosinophilic neurons were observed in the auditory cortex, and a mild but significant decrease in the number of surviving neurons was also detectable. The recovery of MAEPs in both groups was characterized by the appearance of a transient high amplitude (2.67 +/- 0.6 microV) low frequency (62.2 +/- 3.4Hz) wave. The present findings show that cortical neuronal death in the auditory cortex, which results from transient cerebral ischemia in the gerbil, is predictable by detecting the delay in the recovery of MAEPs amplitude and CBF during the very early post-ischemic phase. Clinical data is mandatory for the application of the presented method in clinical cases to save many patients with acute cerebrovascular diseases in the future.

Animals↗

PubMed1997

Effect of byakko-ka-ninjin-to on the efferent activity of the autonomic nerve fibers innervating the sublingual gland of the rat.

The effect of intraduodenal infusion of Byakko-ka-ninjin-to (BN) on the efferent activity of the autonomic outflow to the sublingual gland was observed in the anesthetized rat. Intraduodenal infusion of BN (50-200 mg/kg) resulted in a dose-related increase in efferent activity. The enhancement of the nerve activity following administration of 200 mg/kg BN lasted longer than three hours. It was observed that the suppressive effect on efferent activity due to i.v. administration of hypertonic saline was antagonized by intraduodenal infusion of BN. From these observations it is suggested that Byakko-ka-ninjin-to acts as a facilitatory agent on salivary secretion.

Adrenergic alpha-Agonists↗

PubMed1997

Heterogeneous distribution of early energy failure in experimental focal ischemia of the cat brain.

The distribution of succinate dehydrogenase (SDH) activity and the corresponding changes in specific gravity were studied in cats with experimental focal ischemia. Two hours of tandem occlusion of the middle cerebral artery (MCA) and the conunon carotid artery produced a scattered reduction of SDH activity and corresponding brain edema in the cortex. Recirculation ameliorated the SDH reduction and the scattered pattern disappeared, although the brain edema increased further. Four hours of focal ischemia resulted in diffuse reduction of SDH activity in the MCA-perfused area. The scattered area of SDH reduction after 2 hours of focal cerebral ischemia indicates that the ischemic core is multicentric in the early phase, and that these areas fuse together to form a well demarcated infarction, if the blood flow is not reestablished. A short period of cerebral ischemia produces multicentric small infarcts in the cortex, which resemble granular atrophy.

Animals↗

PubMed1997

Time course of tissue elasticity and fluidity in vasogenic brain edema.

We examined chronological changes in regional tissue elasticity (stiffness) and fluidity (1/viscosity) of the white matter during the development and resolution of vasogenic brain edema. Cryogenic injury was created in the cortex of cat brain, and the brain was prepared for measurement of regional tissue elasticity and fluidity. The results were then compared with the histology and tissue water content. Vasogenic edema developed in the white matter under the lesioned cortex (4-24 h) and was resolved by day 10. Regional tissue elasticity decreased significantly during the initial 24 h (45.3 +/- 32.5% of the control (mean +/- S.D.), and then increased to 158.6 +/- 32.3% of the control level at day 10. Regional tissue fluidity increased to 376.7 +/- 240.4% of the control level during the initial 24 h decreased to 77.7 +/- 17.9% of the control level at day 10. Histological examination of the white matter revealed widening of the inter-fiber space at 4-24 h after lesioning and astrocytosis at day 10. Thus vasogenic edema causes an increase of tissue fluidity with a decrease of tissue elasticity. Reactive astrocytosis after the resolution of edema causes an increase of tissue elasticity with mild decrease in tissue fluidity.

Animals↗

PubMed1995

A new surgical method for canine congenital patellar luxation.

Canine patellar luxation is seen in toy and miniature breeds, and in the majority of cases the problem is medial patellar luxation. When the luxation is left alone, it causes deformity and disorder in the growth of the affected limb. In severe cases, the limb may cease to afunction. Early surgical correction is therefore essential, but the owners are not able to detect the disorder at an early age and surgical intervention in most cases will take place after 6 months of age. The authors were able to have the opportunity to operate at an earlier age by educating breeders and owners. Various techniques have been developed and implemented to correct this disorder with varying therapeutic results. The authors have devised a unique surgical method which has been applied to the numerous cases with good results since 1985. The procedure is to make a longitudinal groove on the medical cortical bone of the tibial tuberosity along the tibial crest, and to place small pieces of artificial ceramic bone or autoplastic bone grafts in the groove, thus laterally transposing the tibial tuberosity and crest. This method makes it possible to put the quadriceps muscles of the thigh, the patella and the patellar ligament in the correct alignment over the femoral trochlea. It is considered appropriate to conduct this operation at 1.0-3.0 months of age when the dog has matured enough to be able to withstand anesthesia and surgical stress.

Animals↗

PubMed1995

[Treatment of tuberculous tracheobronchial stenoses with expandable metallic stent (EMS)s placed during percutaneous cardiopulmonary support (PCPS)].

A 63-year-old woman was taken to a hospital by ambulance because of dyspnea. She was admitted in nearly complete cardiopulmonary arrest. CPR was started immediately, and the patient was mechanically ventilated via a tracheostomy tube. Abnormally high airway pressures 40-50 cmH2O were required during positive pressure ventilation. Saber-sheath like stenoses of the lower trachea 3 cm long and left main stem bronchus 2 cm long were found by bronchoscopy. It was difficult to pass a 3-mm-diameter bronchoscope through these stenoses. The right main stem bronchus was completely obstructed. A chest radiograph showed a completely collapsed right lung and a scarred upper lobe of the left lung, probably caused by previous tuberculosis. Weaning from the ventilator was attempted over three months. However, the patient could not breathe by herself because of airway obstruction. She was referred to our hospital for the placement of stents into the stenotic parts of the airways. A longitudinally connected Gianturcotype EMS, 15 mm in diameter and 50 mm long was placed in each area of stenosis under general anesthesia. During the placement of EMSs, PCPS was used for 113 minutes instead of mechanical ventilation of the lungs. Hemodynamics were stable during PCPS. A bypass flow of 2.0-2.8 l/min/m2 was used. Oxygen saturation of arterial blood taken from an earlobe was maintained at 100%. Blood taken from the left radial artery had a PaO2 of 269.4 mmHg and a PaCO2 of 40.2 mmHg. There were no complications after the procedure. One month later, the stenoses had become slightly dilated.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchial Diseases↗

PubMed1995

[A case of inflammatory bronchial polyp under treatment of tuberculosis].

A 76-year-old man was admitted to our hospital because of pulmonary tuberculosis. He was treated by antituberculosis drugs. Four months later, bronchoscopic examination revealed three polypoid tumors. One of them was a small polypoid lesion with the pus containing acid-fast bacilli. The others were smooth surfaced black polypoid tumors without pus. Although biopsy specimens from these tumors showed a non-specific inflammatory change, the former could be considered as a tuberculous change. Four months later, the polypoid tumors disappeared and anthracosis was found at the site of black polypoid tumors. It is suggested that a polypoid tumor with tuberculous findings was in the earlier stage than the other tumors during the healing process of bronchial tuberculosis.

Aged↗