Biomedical subjects

S Nakajima

Publications and source records attributed to S Nakajima.

At least 163 records · Page 9Linked to original sources

PubMed1998

A simple method of scalp localization using multiplanar reconstruction of MR images.

BACKGROUND: Image-based scalp localization methods currently used are complex and not standardized. The authors have developed a simple yet accurate method for craniotomy localization using multiplanar reconstruction (MPR) algorithms. METHODS: In this method, the goal is to localize a projected point (defined as T) of the center of the lesion on the scalp. An oblique coronal plane is reformatted using a patient's magnetic resonance (MR) images with MPR algorithms to include both the center of the lesion and bilateral external auditory meati. Then the distance between T and the ipsilateral external auditory meatus or sagittal suture (defined as S) is measured along the scalp contour in the plane. The distance between the bregma and S is also measured. These distances are used for scalp localization, using a tape measure in the operating room. RESULTS: We have had successful scalp localization in six clinical cases. It took about 3 min to measure each distance on the MR console. CONCLUSION: This method for craniotomy planning using MPR algorithms is simple and sufficiently accurate.

Craniotomy↗

PubMed1998

Roles of histamine receptor in a guinea pig asthma model.

Histamine plays an important role in bronchoconstriction mediated by histamine receptors which provoke bronchial asthma attack. In this study, we measured H1 and H2 receptors in the guinea pig lung membrane fraction and obtained the following results. The maximum binding (Bmax) of H1 receptors in the guinea pig lung membrane fraction was significantly higher in the OA-sensitized group than that in the non-sensitized group, but affinity (Kd) did not differ between the groups. Otherwise, the maximum binding (Bmax) of H2 receptors in the guinea pig lung membrane fraction was significantly lower in the OA-sensitized group than that in the non-sensitized group. But affinity (Kd) did not differ between the groups. These findings suggest a close association of Histamine receptors both H1 and H2 in the pathology of asthma.

Animals↗

PubMed1998

Effect of TYB-2285 on early and late bronchial responses and airway hyperreactivity in actively sensitized guinea pigs.

1. The effect of a new antiasthmatic drug, TYB-2285 [3,5-bis (acetoxyacetylamino)-4-chlorobenzonitrile], on dual bronchoconstriction and airway hyperreactivity in actively sensitized guinea pigs was investigated. 2. Immediate and late bronchial responses were induced at 1-10 min and 4-7 hr after antigen inhalation, respectively. Guinea pigs were pretreated with TYB-2285 (300 mg kg(-1) PO, as a single dose or consecutively for 7 days). 3. The immediate bronchial response was inhibited only by a multiple administration of TYB-2285. Late bronchial response was inhibited by both administration methods. 4. The numbers of eosinophils, neutrophils and macrophages, but not lymphocytes, in the bronchoalveolar lavage fluid were increased at 4 hr after antigen inhalation. TYB-2285, given singly and consecutively, decreased the numbers of total cells, eosinophils, neutrophils and macrophages. 5. Sensitized guinea pigs showed significant airway hyperreactivity to inhaled histamine. This airway hyperresponsiveness was reversed by a single administration of TYB-2285. 6. Luminol-dependent chemiluminescence of airway-infiltrated cells was slightly inhibited by TYB-2285 (20 microg ml(-1)). 7. The present study shows that TYB-2285 inhibits late asthmatic response and airway hyperresponsiveness, presumably by inhibiting the accumulation and activation of eosinophils and other inflammatory cells.

Animals↗

PubMed1998

Effects of theophylline on lymphocyte phosphodiesterase activity.

1. To clarify part of the bronchodilating effects of theophylline, lymphocyte cyclic AMP (cAMP) and phosphodiesterase (PDE) activity in asthmatic patients and healthy adults were measured. 2. No clear differences in lymphocyte PDE activity were found regarding sexes, ages or the types of asthma. 3. Lymphocyte PDE activity in the asthma group was significantly higher than that in the control group. 4. Lymphocyte cAMP significantly increased at 30 and 60 min after intravenous injection of aminophylline in the asthma group. 5. Lymphocyte PDE activity significantly decreased 60 min after intravenous injection of aminophylline in the asthma group.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1998

Expression of two angiogenic factors, vascular endothelial growth factor and platelet-derived endothelial cell growth factor in human pancreatic cancer, and its relationship to angiogenesis.

Tumour angiogenesis, as assayed by microvessel density (MVD), and the expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) have become established as important prognostic indicators for many tumour types. In this study, MVD and the expression of VEGF and PD-ECGF were examined by immunohistochemical staining of 50 pancreatic cancer tissues, and the relationships between either MVD or the expression of these two angiogenic factors and the clinicopathological features, including survival, were analysed. The expression of VEGF and PD-ECGF proteins were confirmed by Western blot analysis and VEGF mRNA isoforms were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) in five pancreatic cancer cell lines. Twenty-eight (56%) of 50 pancreatic cancers were positive for VEGF protein in cancer cells, and 16 (32%) showed strong PD-ECGF staining in cancer and infiltrating cells. VEGF121 and VEGF165 were identified as the predominant species produced in pancreatic cancer cells. The overexpression of VEGF and PD-ECGF protein significantly correlated with high MVD (P = 0.002, 0.044, respectively). Advanced stage of disease was significantly more frequent in patients with high MVD (P = 0.025). No significant association was found between the expression of VEGF or PD-ECGF and clinicopathological features, except for tumour histology. The expression of PD-ECGF correlated with poor survival (P = 0.011), but MVD and VEGF expression were not found to be useful for the prediction of overall survival. This study suggests that VEGF and PD-ECGF may play an important role in tumour angiogenesis, and that PD-ECGF expression seems to be useful for establishing prognoses for pancreatic cancer.

Blotting, Western↗

PubMed1998

Direct repeat 3-type element lacking the ability to bind to the vitamin D receptor enhances the function of a vitamin D-responsive element.

In a previous study, we identified the element which allows the maximum response to 1,25(OH)2D3 in concert with two vitamin D-responsive elements (VDREs) in the rat 25-hydroxyvitamin D3 24-hydroxylase gene promoter, and designated it an accessory element [Ohyama, Y., Ozono, K., Uchida, M., Yoshimura, M., Shinki, T., Suda, T. and Yamamoto, O. Functional assessment of two vitamin D-responsive elements in the rat 25-hydroxyvitamin D3 24-hydroxylase gene. J. Biol. Chem., 1996, 271, 30381-30385]. The accessory element located adjacent to the proximal VDRE is not capable of binding to the vitamin D receptor (VDR), while its nucleotide sequence resembles the consensus sequence of VDREs, direct repeat 3 (DR3). To clarify the difference between the accessory element and VDREs, the function of the accessory element was compared with that of VDREs. The mutated accessory elements with a single nucleotide substitution showed the capability of binding to the VDR in vitro. However, these mutants still did not act as a VDRE when driven by the heterologous SV40 promoter. The accessory element did not enhance the function of a cAMP-responsive element. The corresponding site of the accessory element in the human 24-hydroxylase is a DR4-type element, and this element did not function as an accessory element. These results indicate that a critical nucleotide sequence is necessary for the binding to the VDR and for mediating the vitamin D effect, and suggest the different regulation between the rat and human 24-hydroxylase gene.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1998

Volumetric object modeling for surgical simulation.

Surgical simulation has many applications in medical education, surgical training, surgical planning and intra-operative assistance. However, extending current surface-based computer graphics methods to model phenomena such as the deformation, cutting, tearing or repairing of soft tissues poses significant challenges for real-time interactions. This paper discusses the use of volumetric methods for modeling complex anatomy and tissue interactions. New techniques are introduced that use volumetric methods for modeling soft-tissue deformation and tissue cutting at interactive rates. An initial prototype for simulating arthroscopic knee surgery is described which uses volumetric models of the knee derived from 3-D magnetic resonance imaging, visual feedback via real-time volume and polygon rendering, and haptic feedback provided by a force-feedback device.

Arthroscopy↗

PubMed1998

Three-dimensional multi-scale line filter for segmentation and visualization of curvilinear structures in medical images.

This paper describes a method for the enhancement of curvilinear structures such as vessels and bronchi in three-dimensional (3-D) medical images. A 3-D line enhancement filter is developed with the aim of discriminating line structures from other structures and recovering line structures of various widths. The 3-D line filter is based on a combination of the eigenvalues of the 3-D Hessian matrix. Multi-scale integration is formulated by taking the maximum among single-scale filter responses, and its characteristics are examined to derive criteria for the selection of parameters in the formulation. The resultant multi-scale line-filtered images provide significantly improved segmentation and visualization of curvilinear structures. The usefulness of the method is demonstrated by the segmentation and visualization of brain vessels from magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), bronchi from a chest CT, and liver vessels (portal veins) from an abdominal CT.

Bronchography↗

PubMed1998

Role of GABA receptors in the bronchial response: studies in sensitized guinea-pigs.

BACKGROUND: Gamma-aminobutyric acid (GABA), an important inhibitory neurotransmitter in the mammalian central nervous system, is also found in peripheral tissues, including the lung. GABA has recently been shown to modulate the contraction of airway smooth muscle. OBJECTIVE: We studied the effect of GABA on the contractile properties of tracheal smooth muscle by measuring the tension of the trachea isolated from non-sensitized and ovalbumin (OA)-sensitized guinea-pigs under isometric conditions. METHODS: Guinea-pigs were sensitized by intraperitoneal doses of OA to prepare a bronchial asthma model. Tracheal spiral rings were prepared from the OA-sensitized as well as normal, non-sensitized guinea-pigs. Using the tracheal preparations, the effects of GABA and GABAa and GABAb receptor agonists (muscimol and baclofen) and antagonists (bicuculline and saclofen) on the basal tone of the trachea and on tracheal contraction induced by electrical field stimulation (EFS) were determined. The effect of GABA on tracheal contraction induced by exogenous acetylcholine was also studied. RESULTS: GABA and GABA agonists and antagonists had no effect on the basal tone of normal guinea-pig tracheae. Both GABAa and GABAb receptor agonists, as well as GABA, suppressed EFS-induced contraction of normal guinea-pig tracheae in a reversible, dose-dependent manner. Moreover, this suppression was reserved to the control level by either GABAa and GABAb receptor antagonists. In tracheal spiral ring prepared from OA-sensitized guinea-pigs, GABA and baclofen caused a smaller reversible inhibition of EFS-induced contraction than in normal tracheal spiral ring, while muscimol inhibited EFS-induced tracheal contraction to a similar extent to that observed in normal tracheae. GABA had no effect on the tracheal contractile response to acetylcholine. CONCLUSION: The results suggest that there may be a biological mechanism mediated by prejunctional GABAb receptors which attenuates cholinergic contraction of airway smooth muscle and that dysfunction of the receptors may underlie the airway obstruction in asthmatics.

Acetylcholine↗

PubMed1998

Beta3-adrenergic receptor gene polymorphism is not associated with hypertension in NIDDM patients without nephropathy.

OBJECTIVE: We studied the relationship between a Trp64Arg mutation of beta3-adrenergic receptor gene and hypertension in Japanese NIDDM patients without nephropathy. RESEARCH DESIGN AND METHODS: Eighty-three Japanese NIDDM patients (46 men, 37 women, known duration of 12 [5-31], age of 55 [40-69] years, median and [range]) with normoalbuminuria and microalbuminuria were studied. The Trp64Arg mutation in the beta3-adrenergic receptor gene was determined by the PCR-RFLP method. RESULTS: The frequency of the mutated allele was not greater in the hypertensive patients (18.2%, n=37) than in the normotensive (20.2%, n=46) patients. Genotypes with a mutate allele (i.e. Trp64/Arg64 + Arg64/Arg64) were observed in 23.5% in the hypertensive patients and in 35.7% in the normotensive patients, respectively. A similar finding in the allele frequency was observed when the analysis was made separately in the normoalbuminuric and microalbuminuric patients, respectively. CONCLUSION: These results suggest that a Trp64Arg mutation in the beta3-adrenergic receptor gene is not associated with hypertension in Japanese NIDDM patients without nephropathy.

Adult↗

PubMed1998

Spatial perception in macroscopic and microscopic surgical manipulations: differences between experienced and inexperienced surgeons.

The spatial perceptions of the phantom surgical field with the naked eye and under the surgical microscope were analyzed in a group of experienced and a group of inexperienced neurosurgeons. The phantom surgical field contained a start point, a virtual gate, and a target point. The virtual gate was an invisible zone arbitrarily set in the phantom surgical field. The examinees were first instructed regarding the position of the invisible virtual gate. Then they were asked to point consecutively to the three points with a suction tube under three different circumstances: with the naked eye, under the microscope, and by watching a navigation monitor. A surgical navigator was used to record the three-dimensional position of the suction tip. The pointing deviation from the suction tip to the center of the virtual gate was evaluated. The pointing accuracy with the naked eye did not differ between the two groups, but that under the microscope was significantly better in the experienced group than in the inexperienced group. Fluctuations in pointing deviation were significantly greater in the inexperienced neurosurgeons, especially with the microscope. Further analysis demonstrated that these differences were attributable to poorer depth perception of the phantom surgical space among the inexperienced neurosurgeons.

Clinical Competence↗

PubMed1998

Mobile fluoroscopic open stereotaxy for MRI-negative angiographic microlesions.

The approach to the deep-seated angiographic microlesion is often difficult, particularly when it is not demonstrated by computed tomography (CT) or magnetic resonance imaging (MRI). We have developed a method to localize these lesions for open stereotactic surgery employing mobile fluoroscopy. Prior to craniotomy, the patient's head is fixed in a stereotactic frame in a position optimal for the routine microscopic surgery. Following the injection of contrast media, the location of the lesion is marked on the fluoroscope monitor. Under fluoroscopic control, the scalp is marked using radiopaque pointer on each side of the patient's head so that the scalp marks and the target lesion overlap each other on the fluoroscope monitor. Thus the imaginary line connecting these scalp marks passes through the lesion. An additional pair of scalp marks is obtained by changing the projection angle of the fluoroscope. By simple calculation, the coordinates of the lesion are obtained as the nearest point to these two imaginary lines, each of which connects a pair of scalp marks. After craniotomy, the lesion is approached using an open stereotactic technique. The first patient had an aneurysm 1.5 mm in diameter that arose from the feeder of the arteriovenous malformation. The second patient had a small residual nidus of arteriovenous malformation 1.5 cm in diameter in the deep frontal lobe, not recognizable by CT or MRI because of artifacts from a previous surgery. Both patients were successfully operated by employing the present method. This method requires only a conventional stereotactic frame and a mobile fluoroscope, and provides simple and reliable localization of the small lesions recognizable only by cerebral angiography.

Arteriovenous Malformations↗

PubMed1998

Therapeutic effect of interstitial photodynamic therapy using ATX-S10(Na) and a diode laser on radio-resistant SCCVII tumors of C3H/He mice.

We examined the effect of interstitial photodynamic therapy (PDT) with a new photosensitizer ATX-S10(Na). This photosensitizer showed the strongest therapeutic effect 2-4 h after administration and was rapidly excreted from individual organs except tumor and liver 24 h after i.v. injection. Microscopic histofluorescent imaging showed fluorescence of ATX-S10(Na) in the cytoplasm of the tumor cells, but not in nuclei and in the vascular wall. Irradiation of Liniac 30 Gly+20 Gly slightly reduced the tumor size, but all mice died of relapse within 60 days after irradiation. In the PDT group, all tumors became non-palpable and healing was achieved in 50% of mice 120 days after PDT.

Animals↗

PubMed1998

Usefulness of scintigraphy with Tc-99m phytate for the diagnosis of alcoholic foamy degeneration.

PURPOSE: Alcoholic foamy degeneration (AFD) is a liver disease causing temporary hepatocyte dysfunction. The prognosis is usually good, but liver biopsy is needed for diagnosis. We report the usefulness of liver-spleen scintigraphy with the radiocolloid Tc-99m phytate for the diagnosis of AFD. PATIENTS AND METHODS: We used liver scintigraphy with Tc-99m phytate to study three patients with AFD diagnosed on the basis of findings from a liver biopsy. RESULTS: Liver-spleen scintigraphy showed hepatomegaly and splenomegaly, and bone marrow was visible, but radioisotope uptake by the liver was uniform. CONCLUSIONS: This pattern of scintigraphic findings is different from that reported for patients with alcoholic fatty livers or severe alcoholic hepatitis, and seems to be specific for AFD.

Adult↗

PubMed1998

Manganese-metalloporphyrin (ATN-10) as a tumor-localizing agent: magnetic resonance imaging and inductively coupled plasma atomic emission spectroscopy study with experimental brain tumors.

OBJECTIVE: We examined whether selective tumor accumulation of a novel manganese-metalloporphyrin (ATN-10) occurs in Fisher rats bearing intracerebral 9L gliomas. METHODS: After intravenous administration of ATN-10, magnetic resonance imaging of brains with tumors or nontumoral vasogenic brain edema was performed. Tissue manganese concentrations were measured by inductively coupled plasma atomic emission spectroscopy until 48 hours after administration of ATN-10, to evaluate its uptake in tumor, normal brain, and peritumoral brain tissue. RESULTS: In magnetic resonance imaging scans, early enhancement was observed in both tumor tissue and regions of nontumoral vasogenic brain edema at 5 minutes after ATN-10 administration. However, delayed enhancement was noted only in tumor tissue, at 24 hours after intravenous injection of ATN-10. Comparison of rat brain specimens and 24-hour magnetic resonance imaging scans revealed that only the viable portions of tumors were enhanced with ATN-10; necrotic regions and areas of peritumoral brain tissue and nontumoral vasogenic edema were not. Significantly greater uptake of ATN-10 was found in tumor samples, compared with normal and peritumoral brain tissue, at 24 hours. A high tumor/normal brain tissue ratio (10.4) was achieved at 24 hours. CONCLUSION: ATN-10, a manganese-metalloporphyrin, is a potentially useful tumor-localizing agent that accumulates and is preferentially retained in viable tumor tissue.

Animals↗

PubMed1998

M protein correlates with the receptor-binding specificity of haemagglutinin protein of reassortant influenza A (H1N1) virus.

From the reassortment experiments between A/Aichi/4/92 and A/WSN/33 (WSN) (H1N1) viruses, two different phenotype viruses which contained the haemagglutinin (HA) gene from A/Aichi/4/92 virus and the neuraminidase (NA) gene from WSN virus were obtained. PW13 and PW15 viruses agglutinated chicken red blood cells (CRBC), while PW10 and PW70 viruses did not. However, the expressed HA proteins of these viruses did not adsorb CRBC. The difference in gene constellation between PW13, PW15 and PW10, PW70 viruses was the membrane protein (M) gene. The former two had the M gene from A/Aichi/4/92 virus and the latter two had that from WSN virus. In PW15-infected cells, haemadsorption of CRBC was observed 30 min later than that of goose red blood cells and the M1 protein migrated from the nucleus to the cytoplasm 30 min earlier than adsorption of CRBC was observed. On the other hand, in PW10-infected cells, haemadsorption of CRBC was not observed through the virus replication and the M1 protein stayed in the nucleus after HA and NA activities reached maximum levels. Co-expression of the M and the HA proteins of A/Aichi/4/92 virus did not help the HA protein gain the ability to adsorb CRBC. However, neuraminidase treatment of COS cells expressing the HA protein of A/Aichi/4/92 virus or MDCK cells infected by PW10 virus restored the ability to adsorb CRBC. We discussed the possibility that the M1 protein helped the NA protein in its role to modify the HA protein on the cell surface.

Agglutination↗

PubMed1998

Excision of cortical dysplasia in the language area with use of a surgical navigator: a case report.

PURPOSE: We have developed an intraoperative optical tracking-based navigational system that allows localization in the operative space. Using three-dimensional reconstruction, this system has provided precise spatial information for intraoperative cortical mapping in patients with intractable epilepsy in whom the lesion lies close to eloquent cortex. METHODS: A 23-year-old man with intractable complex partial seizures (CPS) presented to our institution. Proton-density magnetic resonance imaging (MRI) showed a 3-cm lesion which lay 2 cm beneath the left frontal operculum. A three-dimensional model of the patient was reconstructed using MR modalities. Intraoperatively, subdural grid and strips were placed over the lesion and their electrodes were registered to the three-dimensional model, which was displayed on a monitor. The navigational system was used to localize each electrode on the three-dimensional model. By the second operation, the sites of seizure activity were established and recorded on the three-dimensional model. A bipolar stimulator was also used to determine the speech area. RESULTS: The lesion, which proved to be cortical dysplasia, was removed completely and the cortical speech area was avoided. During the postoperative period, the patient had no neurological symptoms and no seizure activity. CONCLUSIONS: The localization of a lesion and its correlation with epileptogenic foci is important in optimizing treatment in patients with cortical dysplasia. Our navigational system provided accurate localization of the lesion and correlation with the epileptogenic focus and related eloquent cortex. We believe that the safe removal of the lesion was facilitated by this system.

Adult↗

PubMed1998

Age at onset of delusional disorder is dependent on the delusional theme.

The main aim of this study was to investigate whether or not subtypes of delusional disorder diagnosed by DSM-III-R show differences in age at onset and sex distribution. All out-patients first seen at the psychiatry clinic between 1989 and 1994 were diagnosed by DSM-III-R. Of 4144 out-patients, 51 patients (1.2%) were selected as having delusional disorder, and the demographic data and clinical profiles for these subjects were evaluated prospectively by the psychiatrists. Females outnumbered males by a ratio of 3:1. The type of delusional disorder most frequently encountered was the persecutory type, followed by the somatic type, jealous type and unspecified type. The age at onset differed significantly according to the type of delusional disorder, the oldest age at onset being associated with the persecutory type, and the youngest with the somatic type.

Adult↗