Biomedical subjects

Yoshikazu Yoshida

Publications and source records attributed to Yoshikazu Yoshida.

8 recordsLinked to original sources

PubMed2006

A case of nasopharyngeal actinomycosis leading to otitis media with effusion.

Nasopharyngeal actinomycosis is extremely rare, and to our knowledge, only seven cases have previously been reported. Diagnosis of actinomycosis is made by clinical finding, observation of the bacteria and histopathological examination. Treatment for actinomycosis is surgical debridement and administration of antibioticus, especially penicillin for several weeks with good prognosis. We report a case of nasopharyngeal actinomycosis, which lead to otitis media with effusion. Endoscopic surgery and prolonged penicillin administration for 2 months were effective for treatment of actinomycosis in the nasopharynx.

Actinomycosis↗

PubMed2004

A solitary fibrous tumor in the external auditory meatus.

We herein describe a rare case of a spindle-cell neoplasm arising in the external auditory canal. A 38-year-old man presented with a progressive swelling of the entrance of left external auditory meatus. The patient underwent a surgical removal of the tumor. A light microscopic study showed a spindle-cell proliferation with a collagenous stroma and a staghorn-like vascular pattern. The tumor cells were immunohistochemically positive for vimentin and CD34. The tumor was thereafter diagnosed to be a solitary fibrous tumor (SFT). SFTs most commonly occur in the pleura and are supposed to originate from submesothelial connective tissue. Although, several cases of extrapleural SFT have been reported, no SFT arising in the entrance of left external auditory canal have ever been reported in the literature. As a basically benign tumor, it occasionally relapses or metastasizes after excision, and therefore a careful follow up is necessary.

Adult↗

PubMed2004

Oropharyngeal dysphagia in a case of Huntington's disease.

The aim of this study is to analyze dysphagic symptoms of a patient with Huntington's disease (HD) who had having difficulty in swallowing. The patient was a 66-year-old female with HD. Inspection of self-feeding at bedside and videofluorographic swallowing assessment were performed. The features at self-feeding were the tendency of rapid eating, inability for smooth transportation of food to oral cavity, weak lip closure, which resulted in falling of food and eating it again. The videofluorography indicated clumsy tongue movement and postural instability by chorea which caused discoordination between oral and pharyngeal stage. Those ended in spill of liquid to the pharynx and retention of bolus in the oral cavity and vallecula, and aspiration did not occur. Pudding was carefully chewed because of the patient's alertness to the examination. The cognitive disturbance and choreic movement caused dysphagia at the preparatory and oral stages, and chorea also produced the discoordication between the oral and pharyngeal stage. The change of the shape of cups and stable posture were advised to lessen the chance of her aspiration.

Aged↗

PubMed2003

Laryngeal solitary multiple mucosal neuromas without multiple endocrine neoplasia (MEN) type 2B.

The first case of laryngeal solitary multiple mucosal neuromas (MMN) was reported. A 73-year-old man who had complained of hoarseness and abnormal prickly sensation in the throat for 3 months visited our hospital. Many small whitish-yellow nodules were observed in the laryngeal mucosa from the right arytenoid to the interarytenoid region. Using laryngomicroscopy biopsy was performed twice. The pathological study showed neurogenic nodular lesions consisting of regularly arranged nerve bundles with many axons and Schwann cell proliferation, and so MMN was finally diagnosed. As MMN is regarded as a constant component of multiple endocrine neoplasia (MEN) type 2B, screening of MEN type 2B was performed, however, they were all within normal limits. This case was, therefore, diagnosed as a laryngeal solitary MMN without MEN type 2B.

Aged↗

PubMed2003

Attentional modulation of oscillatory activity in human visual cortex.

The effects of attentional modulation on activity within the human visual cortex were investigated using magnetoencephalography. Chromatic sinusoidal stimuli were used to evoke activity from the occipital cortex, with attention directed either toward or away from the stimulus using a bar-orientation judgment task. For five observers, global magnetic field power was plotted as a function of time from stimulus onset. The major peak of each function occurred at about 120 ms latency and was well modeled by a current dipole near the calcarine sulcus. Independent component analysis (ICA) on the non-averaged data for each observer also revealed one component of calcarine origin, the location of which matched that of the dipolar source determined from the averaged data. For two observers, ICA revealed a second component near the parieto-occipital sulcus. Although no effects of attention were evident using standard averaging procedures, time-varying spectral analyses of single trials revealed that the main effect of attention was to alter the level of oscillatory activity. Most notably, a sustained increase in alpha-band (7-12 Hz) activity of both calcarine and parieto-occipital origin was evident. In addition, calcarine activity in the range of 13-21 Hz was enhanced, while calcarine activity in the range of 5-6 Hz was reduced. Our results are consistent with the hypothesis that attentional modulation affects neural processing within the calcarine and parieto-occipital cortex by altering the amplitude of alpha-band activity and other natural brain rhythms.

Adult↗

PubMed2003

Diagnostic significance and clinical applications of chimeric genes in Ewing's sarcoma.

Ewing's sarcoma (ES) is one of the most malignant bone and soft tissue tumors in childhood. Morphologically, ES belongs to the small round cell tumors (SRCT). ES, peripheral primitive neuroectodermal tumor (PNET), and Askin's tumor are classified as ES family tumors (ESFT) because they share a common chromosomal translocation. The EWS-FLI1 chimeric gene is generated by t (11; 22). Other reciprocal translocations resulting in formation of chimeric genes between EWS and ETS family genes (ERG, ETV1, E1AF, and FEV) are t (21; 22), t (7; 22), t (17; 22), and t (2; 22), respectively. Although it is generally difficult to distinguish ES from SRCT, we could easily and quickly distinguish ES from other SRCT by using reverse transcription polymerase chain reaction (RT-PCR). We looked for specific chimeric genes in 23 tumor samples, including three ES clinical samples. We detected five chimeric genes in the three ES samples. Three chimeric genes, all EWS-FLI1, were detected in one ES sample. Different chimeric genes, EWS-ERG and EWS-ETV1, were detected in the other two ES samples. Moreover, because we could not detect specific chimeric genes in samples from non-ESFT, it may be possible to use this technique to diagnose ESFT and to detect tumor cell contamination before hematopoietic stem cell transplantation.

Adolescent↗

PubMed2002

Magnetic responses of human visual cortex to illusory contours.

To examine the neural mechanism underlying illusory-contour perception, we measured the magnetic responses of the human visual cortex to an abutting-line grating inducing illusory contours (test stimulus) and a non-abutting-line grating (control stimulus) using the technique of magnetoencephalography (MEG). In the initial latency period of 60-80 ms, the MEG response to the test stimulus was nearly identical with that to the control stimulus, but in the subsequent period of 80-150 ms, the former was larger than the latter. The origin of the peak MEG response to the test stimulus was estimated to be in the vicinity of striate cortex/extrastriate visual cortex for two of the four subjects. These results suggest that, in accord with those of the previous electrophysiological and functional magnetic resonance imaging studies, illusory-contour signals are generated in the very early stage(s) of processing in the primate visual cortex.

Adult↗

PubMed2002

Surround suppression in the human visual cortex: an analysis using magnetoencephalography.

The responses of neurons in the primate and cat primary visual cortices (V1s) to the stimuli within their classical receptive fields (CRFs) are markedly suppressed by the surrounding stimuli outside CRFs. In the present study, we show that a similar suppressive effect occurs for visually evoked magnetic responses in the human visual cortex. The initial peak amplitude of the magnetic response (at a latency of around 90 ms) to a test grating accompanied by high-contrast surround gratings was smaller than that for the test without the surround. Current source localization with a single dipole model indicated that the initial response originated from cortical activity near the occipital pole in the contralateral hemisphere to the visual stimulation. The peak amplitude for the test decreased with increasing surround contrast, and increased with increasing test contrast. The contrast dependence and the early development of the surround suppression were in agreement with the results of the V1 single-cell studies of monkeys and cats. We suggest that the surround suppression of the initial peak amplitude of the magnetic response may be ascribed to the inhibition of the neural activity at the early processing stage(s), presumably at V1, in the human visual cortex.

Adult↗