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Biomedical subjects

A Ishiyama

Publications and source records attributed to A Ishiyama.

At least 19 recordsLinked to original sources
PubMed2006

Screening of Thai medicinal plant extracts and their active constituents for in vitro antimalarial activity.

To discover antimalarial substances from plants cultivated in Thailand 80%-EtOH extracts from selected plants were screened for in vitro antimalarial activity against the drug resistant K1 strain of Plasmodium falciparum. In total, 86 Thai medicinal plant samples representing 48 species from 35 genera in 16 families were screened and two species (Polyalthia viridis and Goniothalamus marcanii) were found to show notable antimalarial activity (IC50: 10.0 and 6.3 microg/mL). Marcanine A and 16-hydroxycleroda-3,13(14)Z-dien-15,16-olide were identified as the respective major active constituents in P. viridis and G. marcanii, respectively.

Animals↗
PubMed2004

Bayesian classification of myocardial excitation abnormality using magnetocardiogram maps for mass screening.

We propose a novel classification method based on the Bayes rule to utilize the magnetocardiogram (MCG) in noninvasive mass screening. The cardiac excitation is directly tracked by maps of the MCG field generated by myocardial excitation current through the excited wave front. To adopt the characteristics of the excited wave fronts as a parameter for the Bayes theorem, we developed a parameterization procedure that consists of a two-dimensional wavelet approximation and a cluster analysis of magnetic field maps. With the parameter determined by this procedure, the probability of a subject to belong to a disease group or to the normal group is estimated by the Bayes theorem. The subject is classified into the group of the highest probability. We applied the proposed method to ST-T period of MCG data of 6 old myocardial infarction (OMI) patients and 15 normal controls. The method showed sensitivity of 83%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 94% in the classification of OMI patients and normal controls. The processing time is less than 5 seconds per one subject. It suggests a possible application of the proposed method in mass screening of abnormal MCG patterns.

Bayes Theorem↗
PubMed2004

Temporal bone histopathology in dominantly inherited audiovestibular syndrome.

OBJECTIVE: To describe the clinical and pathologic features of a new dominantly inherited audiovestibular syndrome. METHODS: History, examination, and audiometric testing in the proband, brother, and son; quantitative rotational testing in the proband and son; histopathology of the cochlea and vestibular labyrinth in the proband; sequencing candidate genes COCH and MYO7A in the brother and son. RESULTS: Affected family members developed slowly progressive hearing loss beginning in their late 30s and progressive imbalance in their early 70s. Three of four affected had brief (minutes) episodes of vertigo typically occurring a few times per year. Auditory and vestibular function testing documented a slowly progressive loss of auditory and vestibular function. Postmortem examination showed a loss of hair cells in the cochlea and vestibular receptor organs. There were no cellular infiltrates or acidophilic deposits. No mutations were found in the COCH or MYO7A genes. CONCLUSIONS: This dominantly inherited audiovestibular syndrome results in a selective loss of hair cells in the auditory and vestibular end organs. Finding the causative gene could have important implications for understanding the pathophysiology of presbycusis and dysequilibrium of aging.

Adult↗
PubMed2002

Inhibition of the adherence of Escherichia coli strains to basement membrane by Lactobacillus crispatus expressing an S-layer.

AIMS: This study aimed to evaluate the efficiency with which Lactobacillus crispatus JCM 5810 inhibited the adhesion of enteric pathogens to a synthetic basement membrane and to elucidate the mechanism underlying the inhibition. METHODS AND RESULTS: Lactobacillus crispatus JCM 5810 inhibited the adhesion of three diarrhoeagenic Escherichia coli strains to a reconstituted basement membrane preparation called Matrigel, used as a model of a damaged intestinal tissue site. Inhibition was also observed with the use of immobilized laminin, a major component of Matrigel, but diminished after the removal of S-layer protein (CbsA) from JCM 5810 cells. The isolated CbsA inhibited the adhesion of E. coli to both Matrigel and immobilized laminin. Lactobacillus crispatus JCM 5810 and CbsA seem to inhibit pathogenic E. coli from adhering to basement membrane via competition with laminin molecules for binding sites. CONCLUSIONS: These results suggested that not only Lact. crispatus JCM 5810 cells but CbsA alone might prevent pathogens from colonizing damaged intestinal tissues. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to show the applied aspect of Lactobacillus S-layer protein.

Antibiosis↗
PubMed2001

Drop attacks in older patients secondary to an otologic cause.

The clinical features and treatment of seven patients with drop attacks attributable to inner ear disease presenting after age 65 are described. A neurologic or cardiovascular cause of drop attacks was initially suspected. Audiovestibular testing documented a unilateral inner ear disorder. The salient clinical features of these cases are discussed. The patients underwent ablative vestibular surgery, and all compensated well and were free of vertigo and falls up to 10 years postoperatively.

Aged↗
PubMed2001

Unbiased stereological quantification of neurons in the human spiral ganglion.

We applied an unbiased stereological technique, the optical fractionator, on five human archival temporal bone specimens to estimate the total number of spiral ganglion neurons. Available archival human temporal bone specimen has been serially sectioned at 20 microm and every tenth section was stained. All the stained sections passing through the spiral ganglion were used for the analysis. From each section sampled, the counting areas were systematically randomly sampled within the sectional area of the spiral ganglion. The neurons within the counting areas sampled were counted with the optical disector technique. The total number of the human spiral ganglion neurons was estimated by multiplying the number of neurons counted by the reciprocal of the aggregate sampling fraction. We found an average of 41700 neurons with a coefficient of variation of 0.14, which is a significant departure from the previously published data obtained with the assumption-based methods. The mean coefficient of error for the stereological estimates of the total number of human spiral ganglion neurons was 0.078. The present report presents unbiased stereological sampling and counting strategies for the future quantitative studies on the spiral ganglion neurons. The result of the present study provides the first unbiased baseline value of the human spiral ganglion neurons.

Adult↗
PubMed2001

Age-related change in the number of neurons in the human vestibular ganglion.

Dysequilibrium of aging in humans has been speculated to arise from progressive deterioration within anatomical components of the vestibular system. An integral part of this system is vestibular ganglions, which are bipolar neurons that relay peripheral vestibular information to the central nervous system. To assess the effect of aging on the number of human vestibular ganglion neurons, assumption-free stereology in the form of the optical fractionator was used on 20 serially sectioned archival human temporal bone specimens. Donors had no history of vestibular pathology and ranged in age from 2 to 88 years. An average of 25,812 (coefficient of variation = 0.13) vestibular ganglion neurons was found throughout this age range, a significant departure from the results of past studies. Logistics-based regression analysis pointed to a nonlinear pattern of decline in the neuronal population: the number of cells remained roughly constant at about 28,952 cells in youth and then declined gradually between 30 and 60 years of age before leveling off at approximately 23,349 cells in older individuals. This study confirmed the existence of an age-related decline in the primary neurons of the human vestibular system, thus providing one anatomical basis for the increased incidence of imbalance seen with age.

Adolescent↗
PubMed2001

Vertigo and the enlarged vestibular aqueduct syndrome.

An enlarged vestibular aqueduct (EVA) is one of the most commonly identified inner ear bony malformations in children with sensorineural hearing loss of unknown cause. Most previous reports have focused on hearing loss, but individuals with EVA may also experience paroxysmal vertigo lasting minutes to hours. We report the clinical vestibular features and vestibular function testing of two children and one adult with EVA who had a history of sensorineural hearing loss and presented to our Neurotology Clinic for the evaluation of episodic vertigo. All the patients had an antecedent history of profound bilateral sensorineural hearing loss that had been present since early childhood. The onset of vertigo was delayed into adulthood in one patient. Episodes of vertigo could be triggered by minor head trauma or vigorous physical activity. Despite recurrent episodes of vertigo, vestibular function was normal or moderately impaired compared with the severe auditory deficit. Careful analysis of temporal bone CT demonstrated EVA. Associated enlargement of the membranous endolymphatic sac was evident on brain MRI. While hearing loss is a prominent symptom in patients with EVA, vestibular symptoms may cause referral to a neurologist. Although hearing loss occurs early in childhood, vestibular symptoms can be delayed into adulthood, a finding not previously reported.

Age of Onset↗
PubMed2001

Otological manifestations of Churg-Strauss syndrome.

OBJECTIVES/HYPOTHESIS: To describe the clinical features, pathogenesis, and management of the otological complications in Churg-Strauss syndrome (CSS). STUDY DESIGN: Retrospective review of five patients with documented CSS who had otological manifestations in the later stages of CSS. METHODS: The history, treatment, and outcome were evaluated using office and hospital chart data in these five cases. RESULTS: In all cases, otological manifestations occurred during an advanced stage of CSS and was characterized by the presence of dense aural discharge, granulomatous eosinophilic infiltration into mastoid and middle ear, and subacute severe to profound hearing loss. In all cases, the recurrent aural discharge and granulomatous infiltrate was unresponsive to conventional treatment including repeated myringotomies and aggressive antibiotics. Systemic steroid administration resulted in a rapid, complete cessation of aural discharge and reversal or stabilization of hearing loss. Otological manifestations have been stable over a range of follow-up from 1 to 20 years on a maintenance regimen of steroids. CONCLUSIONS: Temporal bone involvement in CSS is rare. Surgical intervention of the temporal bone is relegated to complications that may include infectious mastoiditis and intracranial involvement. Recognition of the association between CSS and otological disease is important because it is highly responsive to systemic steroids, and early steroid treatment may prevent progression to irreversible hearing loss, infectious otomastoiditis, or intracranial complications.

Adult↗
PubMed2001

Potent antimalarial activities of polyether antibiotic, X-206.

In the course of our screening program to discover antimalarial antibiotics, which are active against drug resistant Plasmodium falciparum in vitro and rodents infected with P. berghei in vivo, from the culture broth of microorganisms, we found a selective and potent active substance produced by an actinomycete strain K99-0413. It was identified as a known polyether antibiotic, X-206. We also compared the in vitro antimalarial activities and cytotoxicities of 12 known polyethers with X-206. Among them, X-206 showed the most selective and potent inhibitory effect against both drug resistant and sensitive strains of P. falciparum. Comparison of biological activities and ion-affinities of the above antibiotics suggests that monovalent cations play an important biological role for the intracellular growth of P. falciparum in parasitized erythrocytes. Moreover, X-206 showed potent in vivo antimalarial activity on the rodent model, though the therapeutic window was narrow compared with its selective toxicity in vitro. These observations are the first report of antimalarial activity of X-206.

Actinomycetales↗
PubMed2000

Unbiased stereological quantification of neurons in the human vestibular ganglion.

Vestibular ganglion (VG) neurons are bipolar neurons that relay peripheral vestibular information to the CNS. Neuron counts in normal humans provide a basis for quantitative studies on the effects of aging or pathological conditions in the audiovestibular systems. No prior study has employed unbiased stereological technique to count human VG neurons. This study used unbiased stereology in the form of the optical fractionator to estimate the total number of human VG neurons in archival temporal bone specimens. An average (+/- s.d.) of 27330+/-2593 neurons was found in specimens from five patients with no history of vestibular pathology. This result, a significant departure from results of past studies, provides the first unbiased baseline value to compare with future stereologically based studies on the human VG.

Adolescent↗
PubMed2000

Can migraine damage the inner ear?

BACKGROUND: Auditory and vestibular symptoms and signs are common in patients with migraine, yet little is known about the pathogenesis of these symptoms and signs. OBJECTIVE: To perform clinicopathological correlation in a patient with migraine, sudden deafness, and delayed endolymphatic hydrops. METHODS: A patient with long-standing migraine with aura developed sudden hearing loss in the left ear at the age of 50 years and Ménière disease on the right side at age 73. At age 76, he had a flurry of sudden drop attacks typical of otolithic crisis. He died of unrelated causes at age 81. The brain and temporal bones were removed approximately 24 hours after death. The cochlea and vestibular end organs were dissected after the surrounding bone was carefully removed. RESULTS: The brain and cerebrovasculature were normal. The left cochlea showed prominent fibrosis consistent with an old infarction. The right inner ear showed hydrops, with relatively good preservation of the hair cells in the cochlea, saccular macule, and cristae of the semicircular canals. However, the utricular macule was denuded of hair cells. CONCLUSIONS: The sudden left-sided deafness likely resulted from ischemia, possibly due to migraine-associated vasospasm. Presumably, the right ear suffered only minimal damage when the patient was 50 years old, but this damage later led to the development of delayed endolymphatic hydrops on the right. Otolithic crises are thought to result from pressure changes across the utricular macule. We speculate that loss of hair cells in the utricular macule resulted from a collapse of the utricular membrane onto the macule.

Aged↗
PubMed2000

Migraine and benign positional vertigo.

Because inner ear symptoms are common in patients with migraine, we questioned whether benign positional vertigo (BPV) is more common in patients with migraine than in the general population. We reviewed the records of 247 patients seen in our neurotology clinic over the past 5 years with a confirmed diagnosis of BPV. Each patient had the typical history of BPV, and in each case the characteristic torsional vertical positioning nystagmus was identified. All were interviewed regarding migraine symptoms by means of standard International Headache Society criteria. Migraine was 3 times more common in patients with BPV of unknown cause than in those with BPV secondary to trauma or surgical procedures. Most patients were cured with the particle repositioning maneuver, regardless of the cause. Presumably, patients with migraine suffer recurrent damage to the inner ear (due to vasospasm or some other mechanism) that predisposes them to recurrent bouts of BPV.

Adolescent↗
PubMed2000

Fenestration surgery for otosclerosis: CT findings of an old surgical procedure.

Numerous attempts to deal surgically with otosclerosis were made before the current method of stapedectomy with stapes prosthesis was established. We report a case with unique CT findings of a patient who underwent fenestration surgery for otosclerosis in the early 1940s. Recognition of this old surgical procedure on the imaging scans may avoid misdiagnosis of labyrinthine fistulae or middle and inner ear malformations.

Aged↗