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Biomedical subjects

H Oka

Publications and source records attributed to H Oka.

At least 19 recordsLinked to original sources
PubMed2006

Primary germinoma arising from the midbrain.

A 29-year-old man presented with diplopia, dysarthria, anisocoria, oculomotor nerve paralysis, abducens nerve paralysis, right facial palsy, and spastic hemiparetic gait. Magnetic resonance imaging (MRI) showed a homogenously enhanced mass in the midbrain. MRI-guided stereotactic biopsy was performed, and the histologic diagnosis was pure germinoma. The tumor disappeared after chemotherapy and radiotherapy. Germinoma should be included in the differential diagnosis of midbrain lesions in young adults. MRI-guided stereotactic biopsy provided a helpful diagnostic clue in a patient with a midbrain lesion.

Adult↗
PubMed2006

Utilization of personal digital assistants (PDA) for intraoperative naming tasks in awake surgery.

The naming task, one of the most important tasks for screening essential language function, is widely used in awake surgery. We employed personal digital assistants (PDA) for the display of objects in three patients performing the naming task during awake surgery for gliomas adjacent to the language area in the left hemisphere. The compact, light-weight, self-illuminated instrument can easily be held close to the patient's face. None had difficulty seeing the screen despite the presence of the surgical drape around the face. The examiner could easily change the displayed objects with a click. However, the PDA screen is too small for use in auditory comprehension tasks such as the Token Test.

Brain Mapping↗
PubMed2006

Cardiovascular dysautonomia in Parkinson's disease and multiple system atrophy.

OBJECTIVES: To determine whether Parkinson's disease (PD) can be distinguished from multiple system atrophy (MSA) on the basis of the assessment of iodine-123 meta-iodobenzylguanidine (123I-MIBG) radioactivity in heart and cardiovascular autonomic function. PATIENTS AND METHODS: Seventeen patients with MSA, 39 with PD, and 25 healthy volunteers underwent 123I-MIBG scintigraphy and hemodynamic autonomic function tests using Valsalva maneuver (VM). Baroreceptor reflex sensitivity (BRS) was measured using the slope of the relation between RR interval and blood pressure during the fourth phase. RESULTS: 123I-MIBG radioactivity in heart of patients with PD was lower than that of control subjects and patients with MSA, but there was some overlap between PD and MSA. BRS in patients with PD who had a 123I-MIBG radioactivity similar to that in MSA was larger than that in patients with MSA, with no overlap in any patient. CONCLUSION: Assessment of BRS may be useful for differentiating between MSA and PD that had a 123I-MIBG radioactivity similar to MSA.

3-Iodobenzylguanidine↗
PubMed2006

Effects of endogenous and exogenous prostaglandin E2 on the proliferation and differentiation of a mouse cementoblast cell line (OCCM-30).

BACKGROUND: Cementum formation is considered to be a critical event for successful regeneration of periodontal tissues. Cementoblasts share many characteristics with osteoblasts. Prostaglandin E(2) (PGE(2)) is an important local factor in bone metabolism. Although the effects of PGE(2) on osteoblasts are well known, its effects on cementoblasts have not yet been established. We examined the effects of PGE(2) on proliferation and differentiation in a mouse cementoblast cell line, OCCM-30 cells. METHODS: OCCM-30 cells were treated with three concentrations of PGE(2) (10, 100, and 1,000 ng/ml). Cell number, alkaline phosphatase (ALP) activity, and expression for mineralization-related genes were determined. Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B (NF-kappaB) ligand (RANKL) expression were also examined by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). RESULTS: The addition of PGE(2) at the highest dose used in this study suppressed cell proliferation of OCCM-30 cells. The expression of mineralization-related marker mRNA, such as type 1 collagen, ALP, bone sialoprotein (BSP), and osteocalcin (OCN), was constitutively detected in OCCM-30 cells. PGE(2) dose dependently stimulated ALP activity and BSP-mRNA expression in OCCM-30 cells at day 3. Transcripts for OPG and RANKL and the protein level of OPG in culture media were upregulated with PGE(2) stimulation. CONCLUSION: These results demonstrate that PGE(2) suppressed cementoblast proliferation but stimulated ALP activity and the BSP-mRNA level, suggesting a role of PGE(2) in controlling cementoblast differentiation, and further indicate that PGE(2) modulates RANKL and OPG expression in cementoblasts; the increase of OPG secreted from cementoblasts with PGE(2) stimulation may be essential to protect the root surface from resorption.

Alkaline Phosphatase↗
PubMed2006

Lhermitte sign during yawning associated with congenital partial aplasia of the posterior arch of the atlas.

We describe the case of a 26-year-old man who presented with symptoms compatible with Lhermitte sign that occurred during yawning. It was associated with congenital partial aplasia of the posterior arch of the atlas. Cervical multisection-detector CT myelography during yawning showed compression of the upper cervical cord due to the inward mobility of the isolated posterior tubercle. The symptoms completely disappeared following removal of the isolated posterior tubercle.

Adult↗
PubMed2004

Immuno-localization of COX-1 and COX-2 in the rat molar periodontal tissue after topical application of lipopolysaccharide.

Up-regulation of prostaglandin E2 (PGE2) production in the periodontal tissue is considered to be important for periodontal tissue destruction. The purpose of the study was to demonstrate the dynamic changes of immuno-localization of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in rat periodontal tissue after topical application of lipopolysaccharide (LPS: 5 mg/ml in physiological saline) from Escherichia coli into the rat molar gingival sulcus. In the normal periodontal tissue, small numbers of junctional epithelium (JE) cells and numerous osteocytes embedded in alveolar bone constitutively expressed COX-1. The COX-1 expression was not effected by LPS application. JE cells, especially in the coronal portion of JE also expressed COX-2. LPS application induced the JE cells with consequent transient expression of COX-2 with a peak at day 1. These findings suggest that JE cells may play a critical role in first defense line against LPS challenge and PGE2 from JE cells may be responsible for the initiation of periodontal inflammation. In the deep periodontal tissue, cementoblasts and osteoblasts showed constitutive expression of COX-2, which may be induced by continuous cyclic tension force due to occlusal pressure. LPS application caused a transient up-regulation of COX-2 expression in periodontal ligament fibroblasts, cementoblasts and osteoblasts. It is suggested that the inducible production of PGE2 via COX-2 by these cells may be associated with connective tissue destruction and alveolar bone resorption.

Administration, Topical↗
PubMed2003

Importance of re-examination for medulloblastoma and atypical teratoid/rhabdoid tumor.

Medulloblastoma may can be difficult to distinguish from atypical teratoid/rhabdoid tumor (AT/RT), since they resemble each other histologically. We re-examined whether AT/RT was included among cases who had been diagnosed as medulloblastoma. All of fifteen medulloblastomas (10 males and 5 females) diagnosed at the Kitasato University Hospital were collected and stained immunohistochemically. Two cases originally diagnosed as medulloblastoma were reclassified as AT/RT based on histological re-examination including immunohistochemical studies. While these two cases of AT/RT were found during infancy, only one medulloblastoma was found in infancy.Histologically, small rhabdoid cells and large, pale, bland cells were common but typical rhabdoid cells were not seen in the two AT/RTs. Gland-like structures were also seen. The tumor cells in AT/RT, but not those in medulloblastoma, were immunoreactive for vimentin, epithelial membrane antigen and smooth muscle actin. In conclusion, if a diagnosis of medulloblastoma is made histologically, it should be confirmed immunohistologically, since it is difficult to distinguish AT/RT from medulloblastoma. When appropriate treatment was specifically targeted at AT/RT it may improve the outcome.

Adolescent↗
PubMed2002

Long-term outcome of intracranial germinoma with hCG elevation in cerebrospinal fluid but not in serum.

OBJECTIVE: Pure germinomas have a good prognosis compared to those with syncytiotrophoblastic giant cells (STGCs), which show elevated human chorionic gonadotropin or human chorionic gonadotropin-beta (hCG/hCG-beta) levels and relapse frequently. However, the long-term outcome of patients with germinoma and detectable hCG/hCG-beta in cerebrospinal fluid (CSF) but not in serum is unclear. MATERIALS AND METHODS: The outcome of patients with pure germinomas (no increase in hCG/hCG-beta in serum or CSF, 13 cases; group A), germinomas with STGC (increased hCG/hCG-beta in serum, 13 cases; group B) and germinomas with increased hCG/hCG-beta only in CSF (6 cases; group C) was analyzed. RESULTS: All three groups received similar radiotherapy. Groups A and C each showed a 10-year survival rate of 100%, while this was only 69.2% in group B. The 10-year relapse-free survival rates were 92.3%, 69.2% and 83.3% (groups A, B and C, respectively). Groups A and C each had one case of tumor relapse, but there was no recurrence simply by the application of radiotherapy. On the other hand, in group B, tumor relapse was seen in 4/13 (30.8%) cases. Three of them showed relapse within the region of the initial radiation exposure and died despite all available treatment. CONCLUSION: Patients with an increased hCG/hCG-beta level in CSF may be considered to be similar to pure germinomas and should be treated and followed-up carefully.

Adolescent↗
PubMed2002

Surgery of proximal anterior cerebral artery aneurysms.

BACKGROUND: Aneurysms of the proximal segment of anterior cerebral artery (A1) are uncommon, but present a unique challenge to surgeons because of the risk of injury to the nearby perforating arteries. Surgical issues and treatment options, however, have not been detailed in the previous literature. METHOD: We report a consecutive series of 11 patients with A1 aneurysms focusing on the surgical considerations. The A1 aneurysms represented 3.4% of the 322 cerebral aneurysms treated in our hospital in the last 6 years. All patients presented with subarachnoid hemorrhage, and 8 patients (73%) had multiple aneurysms. FINDINGS: All aneurysms were secured by neck clipping via pterional craniotomy without any surgery-related morbidity. All of the aneurysms projected superiorly or posteriorly from the origin of the perforating artery of the A1 segment. The aneurysm dome was tightly adherent to the perforating arteries in 7 cases (64%) and the base extended broadly along the axis of the parent artery in 4 cases (36%). INTERPRETATION: Separating the perforating arteries from the neck or dome of the A1 aneurysm and preserving the vessel presents a substantial challenge to the surgeon, because the aneurysm is almost always behind the parent artery in the surgical field, making it difficult to achieve good access for this particular type of dissection. Consideration should be given to additional orbitotomy, wide opening of the Sylvian fissure, mobilization of the MCA and ICA, selection of aperture clip and intra-operative shortening of the clip blades.

Adult↗
PubMed2001

Separation of WAP-8294A components, a novel anti-methicillin-resistant staphylococcus aureus antibiotic, using high-speed counter-current chromatography.

The WAP-8294A complex was isolated from the fermentation broth of Lysobacter sp. WAP-8294, whose major component, WAP-8294A2, showed a strong activity against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci in vitro, and also exhibited a potent activity against MRSA in vivo. The previous separation procedure using the conventional chromatographic methods was laborious and time-consuming, and the recovery of the desired compound was often unsatisfactory. In the present study, high-speed counter-current chromatography (HSCCC) was applied to the separation of the main components of the WAP-8294A complex. Due to the high polarity of the target compounds, we selected a hydrophilic two-phase solvent system composed of n-butanol-ethyl acetate-aqueous 0.005 M trifluoroacetic acid (1.25:3.75:5, v/v/v) which provided a suitable range of partition coefficient values for these compounds. Although the settling time of this solvent system was much longer than the optimum range, suggesting a low retention of the stationary phase under the standard experimental conditions, the separation was successfully performed at the low flow-rate of 0.5 ml/min. A sample size of 25 mg yielded pure fractions of three components (1-6 mg). The identification of each component was carried out by HPLC and fast atom bombardment mass spectrometry. The method will contribute to the clinical development of WAP-8294A2 as an anti-MRSA agent.

Countercurrent Distribution↗
PubMed2001

Analysis of pain-related somatosensory evoked magnetic fields using the MUSIC (multiple signal classification) algorithm for magnetoencephalography.

We evaluated the effectiveness of the Multiple Signal Classification (MUSIC) algorithm by analysing pain-related somatosensory-evoked magnetic fields (SEFs) by 148-channel whole-head-type magnetoencephalography. MUSIC peaks of middle latency components were located around the primary somatosensory cortex (SI), contralateral to the stimulated finger. Long latency components were located around the bilateral secondary somatosensory cortices (SII) and cingulate gyri. Peaks at the SII and cingulate gyri were more prominent on very painful and moderately painful stimulation than on weak stimulation. The results were in very good agreement with results from single dipole estimation. These findings suggest that the MUSIC algorithm could be a useful tool for analysis of pain-related SEFs.

Adult↗