Shinya Sato

Spin trapping agent, phenyl N-tert-butylnitrone, reduces nitric oxide production in the rat brain during experimental meningitis

Phenyl N-tert-butylnitrone (PBN) is a spin trapping agent previously shown to exert a neuroprotective effect in infant rat brain during bacterial meningitis. In the present study, we investigated the effect of systemic PBN administration on nitric oxide (NO) production in a rat model of experimental meningitis induced by lipopolysaccharide (LPS). We assessed the NO concentration in rat brain tissues with an electron paramagnetic resonance (EPR) NO trapping technique. In this model, rats receiving intracisternal LPS administration showed symptoms of meningitis and cerebrospinal fluid (CSF) pleocytosis. The time course study indicated that the concentration of NO in the brain reached the maximum level 8.5h after injection of LPS, and returned to the control level 24 h after the injection. When various doses of PBN (125–400 mg/kg) were injected intraperitoneally 30 min prior to LPS, NO production in the brain was reduced with increasing PBN dose (250 mg/kg suppressed 80% at 8.5h after LPS injection), and white blood cells (WBC) in CSF were significantly decreased. We concluded that reduction of NO generation during bacterial meningitis contributes to the neuroprotective effect of PBN in addition to its possible direct scavenging of reactive oxygen intermediate (ROI).

Cerebral blood flow and oxygen metabolism in infants with hydrocephalus

In this study, regional cerebral blood flow (rCBF) and the cerebral metabolic rate of oxygen (rCMRO2) were measured using positron emission tomography (PET) with oxygen-15 radiopharmaceuticals to clarify the pathophysiology of ventriculomegaly in the developing brain. Four hydrocephalic infants without severe neurological deficit were studied. Hypoperfusion was observed in the frontal, parietal, and visual association cortices which surrounded dilated anterior or posterior horns of the lateral ventricle. Lower rCMRO2 values than adult rates were observed in all cases. In the infants with markedly enlarged anterior or posterior horns, the surrounding cortices showed relatively lower rCMRO2 values with the fall of rCBF. Postoperative studies were performed in two infants. rCMRO2 increased in every region after ventriculoperitoneal shunting, but little change was observed in rCBF. These results indicate that metabolic deterioration occurs in the developing brain with hydrocephalus.

Angiographic findings of ischemic stroke in children.

A cooperative study was undertaken in the Tohoku district of Japan to investigate the relatively rare phenomenon of cerebral infarction in children. The purpose of the present paper is to describe the cerebral angiographic findings in 48 children whose ischemic lesions were confirmed by CT scan. The majority of lesions were considered to be idiopathic. The areas of cerebral infarction appearing in the CT scans were located in the territory of the middle cerebral artery including the basal ganglia. Angiographical abnormalities were observed in 40 patients (83%). The majority occurred in the supraclinoid portion of the internal carotid artery and in the cisternal portion of the middle and anterior cerebral arteries. Multiple lesions, such as in the C1, A1, and M1 or the C1, M1, and M2 segments were observed in 22 cases. These lesions generally appeared in continuation; no bilateral intracranial lesions were observed. Repeated angiography was performed in 22 cases, and in 55% of these some recovery of the lesions was seen.

Evaluation of Tethered Cord Syndrome Associated with Anorectal Malformations

The clinical courses of four patients with occult spinal dysraphism who were also found to have anorectal malformations and tethered cord syndrome are evaluated in this report. These patients were among 27 patients with occult spinal dysraphism treated in the Division of Neurosurgery of Tohoku University School of Medicine during the last 3 years. All four patients experienced urinary disturbances early in life, and initially, these disturbances were considered to be caused by urogenital malformations. As a result, treatments were delayed. Only one patient with male Turners syndrome exhibited mental retardation. Other symptoms, such as sensory disturbance and pain in the lower extremities, became apparent from complaints by the patients without atresia ani. When surgery was performed earlier in our patients with occult spinal dysraphism, the outcome was better. We believe in early surgery for tethered cord syndrome, although there is no consensus for the timing of this surgery. Unfortunately, the diagnosis of tethered cord syndrome was delayed in our four patients. However, because occult spinal dysraphism and anorectal malformations seem to be closely related, the presence of anorectal malformations may result in an earlier diagnosis of tethered cord syndrome.

Loss characteristics of infrared hollow waveguides in multimode transmission

The loss characteristics in multimode transmission were studied for hollow waveguides, and simple equations for optical power attenuation were derived. The equations that were derived by the electromagnetic wave theory and the geometrical optics theory coincide exactly. If the transmission loss is small, the optical power attenuates exponentially with the length of the waveguide. The transmission loss increases in proportion to the inverse of the bore radius and the square of the launch angle. The theoretical values that were calculated by the present equations were in good agreement with the data measured for the SiO2 and ZnSe-coated Ag hollow waveguides.

Radiation thermometry for low temperatures using an infrared hollow waveguide

Various optical fibers were compared theoretically for application to remote radiation thermometry. The highest optical transmission efficiency is attained with a fluoride glass fiber for the temperature range of > 700°C, with a halide crystalline fiber for 120 to 700°C, and with a dielectric-coated metal hollow waveguide for < 120°C. To realize remote sensing of lower temperatures, i.e., from room temperature to ~300°C, a radiometric experiment was carried out using a Ge-coated Ag hollow waveguide. When ambient temperature changed from 22 to 50°C, a serious error arose in the measured temperature, which is attributed to the increase of thermal radiation from the heated waveguide. Since the effect of such noise radiation is inevitable in thermometry using infrared fibers, we propose a measurement method to compensate for the noise level. With the compensation, the effect of ambient temperature was reduced successfully and reliable thermometry was established.

Abscess formation associated with pituitary adenoma: A case report: Changes in the MRI appearance of pituitary adenoma before and after abscess formation.

Background: Pituitary abscess is an extremely rare finding. The abscess may arise as a primary pituitary lesion or be associated with parasellar pathology. It is important for pituitary abscess treatments to perform early diagnosis. In this report, we describe a case of pituitary adenoma in which MRI findings changed during the follow-up period and strongly suggested progression to pituitary abscess arising from adenoma. Case Description: In a 73-year-old female, pituitary adenoma had been incidentally detected; MRI showed typical findings of pituitary adenoma, and we had followed up the pituitary lesion and clinical symptoms. Six months later, she had oculomotor nerve palsy and symptoms of hypopituitarism. Hematological examination revealed inflammation and hypopituitarism. MRI showed striking changes in the signal intensity of the pituitary lesion, and strongly suggested occurrence of sinusitis and pituitary abscess ascribed to pituitary adenoma. She was admitted and endoscopic transsphenoidal surgery was performed. The sellar floor was destroyed, and yellowish-white creamy pus was observed. A histopathological study using hematoxylin-eosin staining showed adenoma and inflammatory cells. Aerobic, anaerobic, and fungal cultures were negative. Antibiotics were administered and hormonal replacement was started. Neurological and general symptoms were improved, and postoperative MRI revealed complete evacuation of abscess and removal of tumor. Conclusions: Pituitary abscess within invasive pituitary adenoma is a rare entity, and shows high mortality. Early diagnosis of pituitary abscess is very important for the prompt surgery and initiation of treatment with antibiotics. In our case, changes in MRI findings were helpful to diagnose pituitary abscess, and endoscopic transsphenoidal surgery was an optimal surgical treatment.

Technical Notes on Endoscopic Transnasal Transsphenoidal Approach for Clival Chondrosarcoma

Although there are various operative approaches for clival tumors, a transsphenoidal approach is one of choices when the main tumor extention is in an anterior-posterior direction with a slight lateral extension. However, this approach sometimes provides only narrow and deep operative field. Recently, endoscopic transnasal transsphenoidal approach is quite an effective approach for clival tumors because of the improvement of surgical instruments, image guidance systems, and techniques and materials of wound closure. In this paper, we describe the effectiveness, technical problems, and solution of this approach based on our experiences with two clival chondrosarcomas that was removed by endoscopic transnasal transsphenoidal approach.

Spectroscopic gas sensing with infrared hollow waveguides

Spectroscopic gas sensing was carried out by using an infrared hollow waveguide as a capillary flow cell. A ZnS-coated Ag hollow waveguide is generally the most suitable selection for use as a flow cell, since it exhibits high transmittance over the wide spectral range around 10 micrometers wavelength. For the corrosive gases that cause serious damage to the ZnS film, SiO2- or GeO2-based glass hollow waveguides are applicable. With these low-loss hollow waveguides, CH4, n-C4H10, NO2, and SO2 gases were measured successfully, and a fast response in gas detection as well as a remarkable reduction of gas consumption was demonstrated.

Evaluation of neuronal loss in adult moyamoya disease by 123I-iomazenil SPECT.

BACKGROUND Central benzodiazepine (BZD) receptor imaging is effective to evaluate neuron density in the pathological brain cortex. This study used BZD receptor imaging to evaluate neuronal damage in adult ischemic moyamoya disease. METHODS Single photon emission computed tomography and a novel tracer, 123I-iomazenil, were used to measure BZD receptor density in the brain. Evaluation of early and late images was performed in three asymptomatic, unoperated patients, and six mildly symptomatic, operated patients. RESULTS Uptakes in the frontal, parietal, and occipital lobes of symptomatic patients were significantly lower (p<0.05) than those of asymptomatic patients. The late image/ early image count ratios (L/E ratios) of asymptomatic patients were relatively constant (mean, 0.571; range, 0.550-0.581) in all regions of interest. In contrast, the L/E ratios of symptomatic patients were not uniform. CONCLUSIONS The neuron density was preserved in adult asymptomatic patients despite harboring moyamoya disease. In contrast, the neuronal density was decreased in symptomatic patients even though their symptoms were mild and they had undergone revascularization.