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Biomedical subjects

Y Harada

Publications and source records attributed to Y Harada.

At least 991 records · Page 55Linked to original sources
PubMedDate not supplied

An evaluation of the toxicity of moxalactam in laboratory animals.

The toxicity of moxalactam in laboratory animals was evaluated with six species. The acute toxicity of moxalactam was lower than that of cefazolin. The subchronic and chronic toxicity of moxalactam was studied for periods of one to six months at dosages of 100-3,500 mg/kg per day in rats, 100-1,600 mg/kg per day in dogs, and 100-500 mg/kg per day in monkeys. Treatment-related effects were limited to soft stool, cecal dilatation, and slight anemia resulting from local injury at the injection site in the higher dosage groups. All the effects were reversible and less severe than those caused by cefazolin. Studies of reproduction in rats, mice, and rabbits indicated that moxalactam had no teratogenicity and no adverse effects on fertility of parental animals and on gestation or growth and reproductive capacity of offspring. Comparative studies of nephrotoxiticity in rabbits demonstrated that moxalactam was considerably less nephrotoxic than cefazolin, cefotiam, and cefotaxime.

Animals↗
PubMedDate not supplied

Doxycycline-induced hemorrhagic esophagitis: a pediatric case.

Esophagitis induced by medications has been recognized in adults but rarely in children. A child with hemorrhagic esophagitis resulting from taking doxycycline tablets for treatment is described and the pathophysiology of this condition is discussed. In pediatric cases treated by tablets or capsules, the possibility of medication-induced esophagitis should always be considered.

Child↗
PubMedDate not supplied

Spinal cord monitoring using evoked potentials recorded from feline vertebral bone.

A new recording method for continuous spinal cord monitoring has been developed at Rancho Los Amigo Hospital. Using peripheral nerve stimulation, spinal evoked potentials (SEPs) are recorded from cancellous bone of spinous processes. This neurologically noninvasive technique provides a highly reproducible and consistent signal, unaffected by biologic noise and surgical handling of the spinal column. Moreover, the evoked response is extremely sensitive to changes in functional integrity of the spinal cord. In experimental spinal cord injuries, produced by localized distraction of the spine, changes of the evoked responses were well correlated with the change in spinal cord function.

Animals↗
PubMedDate not supplied

Natural infection of chimpanzees with new lentiviruses related to HIV-1/SIVcpz.

To determine newly identified lentiviruses, termed simian immunodeficiency virus (SIV)cpz97CG4 and SIVcpz97CG6, from two wild-captured juvenile brother chimpanzees in the Republic of Congo, subgenomic pol (integrase, 288 bp), 5'tat/rev-env Cl (including vpu, 354 bp) and env (C2-C4, 544 bp) gene fragments were amplified and sequenced. The analysis revealed significantly discordant phylogenetic positions of SIVcpz97CG in each genomic region. In the trees derived from partial env sequences (V3), both SIVcpz strains clustered in human immunodeficiency virus type 1 (HIV-1) subtype A. However, in the trees derived from partial pol (integrase) and 5'tat/rev-env C1 (including vpu) sequences, they clustered independently from any of the known HIV-1 subtypes. Especially, in the 5'tat/rev-vpu tree, they branched before the root of HIV-1 group M. These findings suggest that these Congolese SIVcpz genomes are mosaic, probably due to a recombinational event in the recent past, and it provides evidence for a rather recently occurring cross-species transmission between humans and chimpanzees.

Amino Acid Sequence↗
PubMedDate not supplied

Immunodeficiency with increased immunoglobulin M associated with growth hormone insufficiency.

Growth hormone deficiency associated with hypogammaglobulinemia has been reported only in a few publications. Our patient was a male with recurrent episodes of infections. Serum immunoglobulin (Ig) G was extremely low although IgM concentration was much greater than the normal limit. Growth hormone responses to insulin, 1-Dopa and growth hormone-releasing hormone were low. The mean growth hormone concentration during sleep was less than the normal limit. These results are consistent with hyper-IgM immunodeficiency associated with growth hormone deficiency. The mode of transmission appears to be autosomal dominant. This combination has not been reported previously.

Adolescent↗
PubMedDate not supplied

The mouse factor H allotypes with multiple amino acid replacement, H.1 and H.2 show indistinguishable co-factor activity for factor I.

The authors report the functional analysis of the purified mouse factor H allotypes H.1 and H.2, which were clearly distinguished from each other by an immunodiffusion test. Both allotypes acted as a co-factor for factor I in cleaving mouse C3b and we found no significant difference between their activities. The results strongly suggest that the function of mouse factor H for the co-factor activity has been well conserved between two allotypes.

Alleles↗
PubMedDate not supplied

Successful treatment of supraventricular tachycardia with flecainide acetate: a case report.

BACKGROUND: Efficacy of flecainide acetate for the treatment of fetal supraventricular tachycardia with cardiac failure was reported. CASE: For a case in which maternal digoxin therapy failed, flecainide acetate (400 mg/day) is used from 27 weeks. Cardioversion with improved cardiac function occurred 6 days after treatment. Fetal serum flecainide acetate level was 292 ng/ml which was 64% of the maternal level (453 ng/ml). No adverse maternal side effects were noted with 11 weeks of therapy. A vigorous male baby, weighing 3,610 g, Apgar 8/9, Ua-pH 7.24, was born. He is now 1 year of age and in good condition with medication of 5 mg/kg flecainide acetate. CONCLUSION: Flecainide acetate seemed to be safe for both mother and fetus, and effective for the treatment of fetal supraventricular tachycardia which is refractory to transplacental digoxin therapy.

Abdomen↗
PubMedDate not supplied

Experimental study of a frog semicircular canal nerve: influence of the initial cupular position.

The posterior semicircular canal of the frog was stimulated by mechanical endolymphatic flow toward either an ampullofugal (excitatory) or ampullopetal (inhibitory) direction. The magnitudes of the responses as the cupula was moved to various positions were compared. When the same amount of stimulus was given in the same direction, the responses were equal, regardless of the initial position of the cupula.

Action Potentials↗
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Influence of elastase and hyaluronidase on the ciliary interconnecting systems in frog vestibular sensory cells.

Bullfrog vestibular end organs were incubated in frog Ringer's solution, hyaluronidase and elastase. When assessed by scanning electron microscopy, long-time incubation in frog Ringer's solution caused damage to side links. Elastase caused severe damage to tip links with a slight alteration to side links. The glycocalyx of the hair cells decreased after incubation in elastase or hyaluronidase. Electrophysiological measurements showed a remarkable decrease in compound action potentials after the elastase treatment, while no change was observed after the long-time incubation in frog Ringer's solution or hyaluronidase. The results are in agreement with the hypothesis that tip links are involved in mechanotransduction, and side links keep the cilia arranged in a bundle.

Actin Cytoskeleton↗
PubMedDate not supplied

Isolated vestibular sensory cells in the guinea pig.

Vestibular sensory cells were isolated from the utricular macula or cristae ampullares of the guinea pig by enzymatic and mechanical dissociation. The isolated cells were classified into three types: flask-shaped type I sensory cells, rod-shaped type II sensory cells and round-shaped supporting cells. The cilia of type I sensory cells in the crista ampullaris were longer than those in the corresponding cell type in the utricular macula, while no morphological differences of the cell bodies were noted between crista ampullaris and utricular macula. Isolated living vestibular cells have a motile capacity. After exposure to a hypo-osmotic medium, the type I sensory cells showed tilting of the hair bundle. This change in shape may be closely related to the active mechanical transduction control.

Animals↗
PubMedDate not supplied

Effect of glycerol on the guinea pig inner ear after removal of the endolymphatic sac.

The effects of glycerol were investigated in guinea pigs in which the endolymphatic sac (ES) and duct (ED) had been obliterated unilaterally. Twenty-four hours after obliteration of the right ES and ED, glycerol was injected intraperitoneally. One to two hours after administration of glycerol, collapse or folding of Reissner's membrane was observed in the operated cochlea. No remarkable change was found in the nonoperated ear. The lumen of the ES of the nonoperated ear collapsed with intraluminal stainable substance within 1 h. The volume of the stainable substance increased with time and could still be seen 4 h after the injection of glycerol. Twenty-four hours after the injection of glycerol, the configuration of the ES was normal again. In addition, the animals showed marked unilateral (operated side) vestibular dysfunction after injection of glycerol. These findings suggest that the ES also has a secretory capacity and plays an important role in inner ear fluid volume and pressure regulation.

Animals↗
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Three-dimensional organization of cytoskeletons in the vestibular sensory cells.

The cytoskeletal organization of the guinea pig vestibular sensory cells was investigated employing the saponin perfusion method using scanning electron microscopy as well as immunohistochemical technique. The intermediate filaments were demonstrated in the sensory cells. They were usually seen surrounding the nucleus and extending through the cytoplasm which connected the nuclear membrane to the plasma membrane, cuticular plate or other cytoorganelles. These findings may suggest that the intermediate filaments provide mechanical support to the cell and its nucleus. Microtubules were found mainly in the supranuclear portion of the cells and run parallel to the main axis of the cell body, which is directly connected to the cuticular plate. These findings may suggest that the microtubules provide mechanical support to the cell and may be closely related to the sensory cell transduction system. The actin filaments were densely packed in the site of the cuticular plate. They also distributed throughout the cytoplasm, which appeared as a dense network in the periphery region. These findings support the idea that the actin filaments could be responsible for sensory cell transduction as well as to give mechanical strength to the surface of the cell and enable the cell to change its shape and move.

Actins↗
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Polychromatic labeling of otoconia for the investigation of calcium turnover.

The calcium ion turnover into otoconia of adult guinea pigs was investigated by the use of different fluorochromes, i.e. tetracycline (TC), calcein (Cal) and alizarin complexone (AC). The administration of all fluorochromes induced yellow (TC), green (Cal) and red (AC) fluorescence on the outer surface of otoconia, respectively. Sequential polychromatic labeling with AC followed by TC induced only red fluorescence after 1 week administration of TC, combined fluorescence after 2 weeks administration of TC and only yellow fluorescence after more than 3 weeks of administration of TC. The otoconia labeled with both AC and TC showed red fluorescence on the side faces of otoconia and yellow fluorescence on the terminal faces. These results may indicate the existence of a dynamic exchange of calcium ions in the otoconia and this exchange is mainly restricted to the terminal faces. The sequential polychromatic labeling may thus be of great use for the further investigation of the calcium dynamics of otoconia.

Acoustic Maculae↗
PubMedDate not supplied

Effect of streptomycin on the otoconial layer of the guinea pig.

The effects of streptomycin on the otoconial layer of the adult guinea pig were investigated using scanning electron microscopy. Administration of streptomycin induced a reduction of otoconia with formation of giant otoconia. These phenomena reached their maximum 4 weeks after the cessation of streptomycin intoxication in the utricle and between 2 and 6 weeks after in the saccule. Otoconia began to recover in the utricle 4 weeks and in the saccule 6 weeks after the cessation of streptomycin intoxication with an increasing number of small otoconia. Eight or 10 weeks after the cessation of streptomycin intoxication, the otoconial layer has completely recovered in both the utricle and saccule.

Animals↗
PubMedDate not supplied

Role of tenascin in human immunoglobulin A nephropathy.

Tenascin is a component of the extracellular matrix that responds rapidly to inflammation or injury. The activity index and chronicity index of immunoglobulin A nephropathy are mainly used to decide whether or not steroid therapy is indicated, but are sometimes difficult to evaluate histologically. We investigated whether tenascin staining of the glomeruli was an indicator of the activity or chronicity indices in patients with immunoglobulin A nephropathy. Tenascin staining was evaluated immunohistochemically in 38 renal specimens, including 32 from patients with immunoglobulin A nephropathy and six from control kidneys, and the extent of staining was scored. Tenascin staining was correlated with the chronicity index (r = 0.643, P < 0.0003) but not with the activity index.

Adolescent↗
PubMedDate not supplied

Metabolic disorder of otoconia after streptomycin intoxication.

Little is known about the origin or the metabolism of otoconia. Streptomycin sulfate was found to cause a decrease in their number on the otolithic membrane of the utricle and saccule in guinea pigs. The remaining otoconia on the otolithic membrane varied in shape and size and giant otoconia with multilayered arrangement were observed by means of a scanning electron microscope. These otoconia contained the normal amount of calcium in the form of standard calcium calcite crystal. The lost otoconia were found attached to the surface of some vestibular dark cells. Otoconia in this new position were irregular, shrunken or fragmented. Their calcium content, measured with an X-ray micro-analyzer, was variably diminished. The dark cells appeared to be actively engaged in absorption of calcium ions, from the attached otoconia. The dark cell is considered to be a receptacle for the disposal of otoconia.

Animals↗
PubMedDate not supplied

Scanning electron microscopic study on the distribution of epithelial cells in the Eustachian tube.

Canine Eustachian tube epithelium was examined by means of the scanning electron microscope. The part of the tube at the bone-cartilage junction was found to be the most active. It is here that goblet cells and large numbers of ciliated cells were found. Cilia were dense and covered by a mucus blanket. Near the tympanic end of the Eustachian tube, goblet cells were more numerous and ciliated cells less so. Near the pharyngeal end, goblet cells were numerous, while cilia were scanty and not uniform in length. Our findings support the concept that middle ear clearance is carried out by an active mucociliary mechanism as in other parts of the upper respiratory system.

Animals↗