Biomedical subjects

N Ogata

Publications and source records attributed to N Ogata.

At least 91 records · Page 5Linked to original sources

PubMed1998

Embolization of cerebral aneurysms using Guglielmi detachable coils--problems and treatment plans in the acute stage after subarachnoid hemorrhage and long-term efficiency.

This study investigated the problems in treating ruptured aneurysms using Guglielmi detachable coils (GDCs) in the acute stage and evaluated the long-term efficacy in a series of 25 patients with 29 aneurysms. Eight patients with ruptured aneurysm treated within 2 weeks of the onset of subarachnoid hemorrhage (SAH) suffered no mortality or morbidity related to the procedure. Five patients achieved good outcomes despite severe SAH and returned to their previous lives. Three patients had poor clinical outcomes, two related to vasospasm and one related to pulmonary complication. More than 9 months follow-up was completed in 14 patients with 16 aneurysms. All six small aneurysms with small necks were completely obliterated and no recanalization was seen, and two of the eight large or giant aneurysms were completely obliterated. Recanalization was seen in four large or giant aneurysms and one small aneurysm due to coil compaction within 13 months. One patient died of rupture of a large aneurysm 18 months after complete obliteration of the aneurysm. Embolization using GDCs in the acute stage after SAH can prevent rerupture of cerebral aneurysms. However, recanalization due to coil compaction was the major problem in the chronic stage. Intensive follow-up and additional embolization, if necessary, is important.

Aged↗

PubMed1998

Aneurysm surgery in the acute stage: results of structured treatment.

To evaluate the results of a structured treatment approach to aneurysm surgery in the acute stage, 150 consecutive patients with aneurysmal subarachnoid hemorrhage were studied, including 46 males and 104 females; World Federation of Neurological Surgeons grade I: 21 cases, II: 65, III: 41, IV: 23; day of operation < or = day 3: 103 cases, < or = day 7: 131. Patients underwent angiography on the day of admission or the next followed by surgery. The lamina terminalis and the membrane of Liliequest were routinely opened at surgery. The aneurysm neck was radically clipped after temporary clipping or trapping of the parent arteries. Intraoperative hemodynamic monitoring was used, and the craniotomies were closed without cisternal, epidural, or subgaleal drains. Nimodipine was given perioperatively (48 mg i.v./day for 10 to 14 days). Cases of symptomatic vasospasm were treated with selective intra-arterial administration of papaverine, sometimes combined with angioplasty. Outcome at discharge and 3 months later is good recovery in 61% and 75%, and death in 6% and 7%. The incidence of symptomatic vasospasm was 17%. Devastating vasospasms were observed in 5%. One-third of patients had mean flow velocities exceeding 120 cm/sec determined by transcranial Doppler sonography between days 4 and 14. Communicating hydrocephalus necessitating ventriculoperitoneal shunt occurred in 9%. Our results clearly show a favorable outcome compared with previous reports, especially with respect to the reduced occurrence of fatal vasospasm, hydrocephalus, and technical insufficiency.

Acute Disease↗

PubMed1998

Relationship between serum 1,5-anhydroglucitol and urinary excretion of N-acetylglucosaminidase and albumin determined at onset of NIDDM with 3-year follow-up.

OBJECTIVE: This prospective study was designed to elucidate the relationship between the serum level of 1,5-anhydroglucitol (1,5AG) and the urinary excretion of N-acetylglucosaminidase (NAG) and albumin in patients who were in the early stages of diabetes. RESEARCH DESIGN AND METHODS: A total of 1,062 male nondiabetic subjects with impaired glucose tolerance were monitored for blood glucose level once every 2-3 months, and the values were evaluated. Of these 1,062 subjects, 112 showed a worsening of glycemia during the observation period to the level seen in diabetes. We began to monitor the glycemia and parameters of renal damage in the 112 patients from the onset of diabetes. RESULTS: The urinary excretion of NAG and albumin were elevated even at the onset of diabetes. The abnormal excretion of NAG and albumin was associated with a change in serum 1,5AG and was quickly reversible when the serum 1,5AG improved. In the 3 years after the onset of diabetes, we obtained at least 18 measurements of one parameter for each patient and calculated the mean. Urinary NAG was found to be significantly correlated with the fasting plasma level of glucose (FPG; r = 0.512, P < 0.0001), the level of HbA1 (r = 0.351, P = 0.001), and the level of 1,5AG (r = -0.790, P < 0.0001). The urinary excretion of albumin was weakly but significantly correlated with levels of FPG (r = 0.383, P < 0.0001) and HbA1 (r = 0.337, P < 0.0001), but it was more strongly correlated with 1,5AG (r = -0.632, P < 0.0001). The level of 1,5AG was significantly correlated with FPG (r = -0.681, P < 0.0001) and HbA1 (r = -0.609, P < 0.0001). CONCLUSIONS: When the renal damage is not severe, the serum level of 1,5AG appeared to be an indicator of the reversible renal damage caused by hyperglycemia, as well as of the severity of the glycemia itself.

Acetylglucosaminidase↗

PubMed1998

Embolization of cerebral arteriovenous malformations (AVMs)--material selection, improved technique, and tactics in the initial therapy of cerebral AVMs.

Successful embolization can be achieved only when the following three factors are correct and in co-operation: catheter tip position, flow control, and the setting time of normal-butyl cyanoacrylate (NBCA). Otherwise, the procedure may end with unsatisfactory results or complications. The current principle of safe and efficient embolization of cerebral arteriovenous malformation (AVM) is based on superselective cannulation of every strategically important feeding pedicle and injection of liquid embolic material under flow control. This study was based upon our experiences of embolizing 92 cases with cerebral AVM performed under the above conditions at our department. Results showed very encouraging new observations with implications for further procedures: total removal of the AVM nidus after embolization was achieved in 90% of the cases, preradiosurgical embolization achieved 52% volume reduction and successfully maneuvered all cases into the gamma knife focal spot. Recently improved microcatheters with increased flexibility and minimal friction made it possible to place the tip of the microcatheter into the nidus with a higher success rate and better safety factors. In order to obliterate a substantial amount of the AVM nidus and prevent penetration into the draining veins, the creation of optimal flow status, and optimal setting time of NBCA have paramount importance.

Arteriovenous Malformations↗

PubMed1998

Developing NLP Tools for Genome Informatics: An Information Extraction Perspective.

Huge quantities of on-line medical texts such as Medline are available, and we would hope to extract useful information from these resources, as much as possible, hopefully in an automatic way, with the aid of computer technologies. Especially, recent advances in Natural Language Processing (NLP) techniques raise new challenges and opportunities for tackling genome-related on-line text; combining NLP techniques with genome informatics extends beyond the traditional realms of either technology to a variety of emerging applications. In this paper, we explain some of our current efforts for developing various NLP-based tools for tackling genome-related on-line documents for information extraction task.

Journal Article↗

PubMed1997

Genetic information 'created' by archaebacterial DNA polymerase.

DNA polymerase catalyses replication of cellular DNA. The reaction requires a primer-template complex, and a new DNA chain grows from the 3' end of the primer along the template; no genetic information is created in this reaction. We demonstrate that DNA polymerase from Thermococcus litoralis, a hyperthermophilic marine Archaea, can synthesize up to 50000 bp of linear double-stranded DNA in the complete absence of a primer-template complex, indicating that genetic information is 'created.' The possibility of DNA contamination in the reaction mixture, which may serve as a primer and/or template, was vigorously excluded; for example, pretreatment of DNA polymerase with DNase I or extensive chromatographic purification of the substrate, deoxyribonucleoside 5'-triphosphates, did not abolish the primer-template-independent DNA synthesis. The DNA synthesized was (CTAGATAT)n, (TAGATATCTATC)n or a related sequence. Similar repetitive sequences are found in centromeric satellite DNA of many organisms. The significance of this ab initio DNA synthesis is that genetic information can flow from protein to DNA.

Archaea↗

PubMed1997

Vascular endothelial growth factor expression in choroidal neovascularization in rats.

BACKGROUND: The pathogenesis of choroidal neovascularization is largely unknown. We investigated vascular endothelial growth factor (VEGF) expression in laser-induced choroidal neovascularization (CNV) in rats. METHODS: Intense krypton laser photocoagulation was applied to the posterior poles of the eyes of pigmented rats to induce CNV, which was confirmed by fluorescein angiography and histopathology. The eyeballs were enucleated 1, 3, 7, 14 and 28 days after laser photocoagulation. Cryostat sections were prepared for immunofluorescence staining using anti-VEGF and macrophage marker (ED1) antibodies. The posterior segments of eyeballs pooled from photocoagulated and control rats were submitted for immunoprecipitation and immunoblotting by the anti-VEGF antibody, and reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of VEGF mRNA. RESULTS: Very weak immunoreactivity for anti-VEGF antibody was found in the ganglion cell layer, inner nuclear layer, and retinal pigment epithelium (RPE) in the normal retina. In the development of CNV, strong positive staining for anti-VEGF antibody was found in photocoagulated areas in the subretinal space and choroid. Double immunofluorescence staining showed that many cells in lasered lesions were positive both for anti-VEGF and macrophage marker ED1 antibody staining in the early stage of this model. Immunoblots showed a positive band for the VEGF molecule in treated but not control animals. RT-PCR results demonstrated upregulation of VEGF transcripts in the CNV model compared with normal animals. CONCLUSIONS: Our findings showed the upregulation of VEGF expression in experimentally induced CNV, where it may be involved in promoting choroidal angiogenesis. Macrophages may be one of the main sources of VEGF in the early stage of the disease.

Animals↗

PubMed1997

GABAB-mediated upregulation of the high-voltage-activated Ca2+ channels in rat dorsal root ganglia.

The mechanism underlying the enhancement of the high-voltage-activated (HVA) Ca2+ current (ICa) after application of baclofen, a GABAB agonist, in neurones of the rat dorsal root ganglia was studied by a combined use of the nystatin perforated patch clamp recording and our rapid superfusion system. Baclofen (50 microM) decreased the peak amplitude of HVA ICa and slowed the onset of the current, i.e. produced a typical G-protein-mediated inhibition of ICa. However, when baclofen was rapidly removed from the medium, the amplitude of the current was rather augmented, exceeding the control value obtained before application of the drug. This enhancement was not due to a shift of the voltage dependence of Ca2+ channel activation or a change in ionic permeability to other ions. The enhancement of HVA ICa by baclofen was sensitive to pertussis toxin treatment. The enhancement was evident during superfusion of baclofen. Since the inhibitory effect of baclofen on HVA ICa was not attenuated, even after a continuous application of baclofen for 10 min, the enhancement was not due to relief from tonic G-protein-mediated inhibition of the current or a desensitization of the GABAB receptor-effector system. An extremely prolonged time course of the enhancement of HVA ICa by baclofen strongly suggests an involvement of some intracellular signal transduction system.

Animals↗

PubMed1997

Impairment of endothelium-dependent relaxation of rabbit aortas by cigarette smoke extract--role of free radicals and attenuation by captopril.

The aim of this study was to examine the effects of the water soluble component of cigarette smoke extract (CSE) on endothelium-dependent relaxation (EDR) of isolated rabbit aortas. The incubation with CSE was found to inhibit EDR in a dose-dependent manner. Co-incubation of the aortic strips with superoxide dismutase (SOD), N-acetylcysteine, glutathione or dimethyl sulfoxide (DMSO), free radical scavengers, attenuated the CSE-induced inhibition of the arterial relaxation. Co-incubation of the strips with captopril (3 mM), an angiotensin converting enzyme inhibitor, also attenuated CSE-induced impairment of vasorelaxation. In parallel experiments using cultured human endothelial cells, CSE suppressed endothelial release of NOx, stable metabolites of nitric oxide (NO). SOD, DMSO and captopril attenuated the suppression of NO production by CSE in association with reduction of free radicals, superoxide anions and hydroxyl radicals, in CSE solution. Neither lactate dehydrogenase release from the cultured endothelial cells nor cell death estimated by trypan blue exclusion test was found after the incubation of the cultured endothelial cells with CSE. The results indicate that free radicals in CSE induce the impairment of EDR, which may be partly due to suppression of NO production and is not due to non-specific cytotoxicity by CSE. Captopril attenuates CSE-induced endothelial dysfunction partly through scavenging free radicals.

Acetylcysteine↗

PubMed1997

Moyamoya disease in Europe, past and present status.

A questionnaire was distributed in early 1996 to 160 leading European neurological, neuro-pediatric and neurosurgical centers to assess the present status of Moyamoya disease in Europe. The response rate was 43%. Information was obtained on a total of 168 patients, of whom 110 had presented before 1992, and 58 from 1993 onward. 82% of the patients were Caucasian. In all other respects, the clinical findings were similar to those observed in Japan. The present study yields an incidence of 0.3 patients per center per year, which is approximately one-tenth of the incidence in Japan. Alongside these results, the history of the recognition and treatment of this disease in Europe is briefly discussed.

Adult↗

PubMed1997

Preferential infiltration by activated eosinophils in allergic sinusitis.

Although Type I allergy is a trigger for provoking chronic inflammation, whether allergic sinusitis (AS) can be distinguished from sinusitis due to chronic infection is still debated. This study was performed to characterize inflammatory cells in AS and to determine whether patients with AS differ from patients with chronic suppurative sinusitis (CSS). 5 patients with AS and 10 patients with CSS were investigated. Cellular infiltration was studied using immunohistochemistry with monoclonal antibodies using CD3, CD4, CD8, CD25, major basic protein (BMK13), eosinophil cationic protein (EG2), neutrophil elastase, and tryptase. There were no differences in CD3+, CD4+, CD25+, and tryptase+ cells between the groups. Whereas the total number of eosinophils (BMK13+) also did not significantly differ, the number of activated eosinophils (EG2+) was significantly higher (P < 0.05) in patients with AS. Furthermore, a statistically significant increase in the percentage of activated eosinophils to total eosinophils (P < 0.05) was observed in patients with AS. In contrast, the number of neutrophil elastase+ cells was significantly higher (P < 0.05) in patients with CSS. These results suggest that patients with AS can be distinguished immunohistochemically from patients with CSS, with AS being distinguished by activated eosinophil infiltration.

Adolescent↗

PubMed1997

Expression of transforming growth factor-beta mRNA in experimental choroidal neovascularization.

PURPOSE: Transforming growth factor beta (TGF-beta) is a multifunctional cytokine that modulates biological events as diverse as wound healing and angiogenesis and which may be important in the pathogenesis of choroidal neovascularization. We investigated the mRNA expression of TGF-beta isoforms in a model of experimental choroidal neovascularization induced by krypton-laser photocoagulation. METHODS: Rat TGF-beta 1, mouse TGF-beta 2 or TGF-beta 3 cDNAs was inserted into the pBluescript vector to prepare antisense and sense riboprobes. Intense laser burns were applied to the posterior poles of the eyes of pigmented rats according to a protocol described for producing choroidal neovascularization in these animals. At intervals up to 4 weeks after photocoagulation, the eyes were obtained and cut into thin sections. The sections were subjected to in situ hybridization with digoxigenin (DIG)-labeled single-strand riboprobes synthesized from each TGF-beta cDNA. RESULTS: In normal adult rat retinas and choroids, TGF-beta 1 mRNA was found only in cells of the ganglion cell layer, TGF-beta 2 mRNA was found in cells of the ganglion cell layer and choriocapillaris endothelium, whereas TGF-beta 3 mRNA was not detected at all. During the process of neovascularization, TGF-beta 1 and TGF-beta 2 mRNAs (the latter being expressed more prominently) were detected in retinal pigment epithelial cells, fibroblast-like cells and the endothelium of the neovascular region. TGF-beta 2 was the predominant isoform of TGF-beta, and its expression was especially strong in the endothelium of the choroidal neovascularization at 2 weeks. However, TGF-beta mRNAs was decreased in cells 4 weeks after photocoagulation. CONCLUSIONS: Our findings suggest that TGF-beta may act in the retina as a neurotrophic agent, since TGF-beta 1 is normally transcribed in ganglion cells and TGF-beta 2 is also transcribed in ganglion cells and choriocapillaris endothelium. TGF-beta 1 and TGF-beta 2 mRNA expression were increased in photocoagulated lesions from 3 days to 2 weeks after laser treatment. Therefore, it is likely that TGF-beta acts as a mediator of the neovascularization process.

Animals↗

PubMed1997

Infectivity and pathogenicity in chimpanzees of a surface gene mutant of hepatitis B virus that emerged in a vaccinated infant.

Hepatitis B virus (HBV) variants with amino acid mutations in the a epitope of the major surface protein have been identified, and questions have been raised regarding their biologic properties. Dilutions of serum that contained the first such described HBV mutant, with an Arg-for-Gly substitution at codon 145 of the S gene, were inoculated into 6 seronegative chimpanzees. Five of the animals developed serologic and/or biochemical evidence of hepatitis B. A polymerase chain reaction-based assay that discriminated between the wild type and mutant viral genomes revealed that a pure population of the mutant genome was present in the 10(-6) and 10(-7) dilutions of the index serum, resulting in infection of the chimpanzees receiving these dilutions only with the mutant virus. A clone of the mutant virus replicated normally following transfection in vitro. Thus, this HBV surface gene mutant is viable, infectious, and pathogenic in chimpanzees.

Animals↗

PubMed1997

Paramedian supracerebellar approach to the upper brain stem and peduncular lesions.

OBJECTIVE: The infratentorial paramedian supracerebellar approach is useful for lesions involving the upper brain stem or the cerebellar pedunculi. We provide a precise description of this approach and its indications. METHODS: Four patients were operated on using this approach. The lesions included a squamous cell carcinoma, a glioblastoma multiforme, a hematoma, and a cavernoma. The lesions involved the quadrigeminal plate, the superior cerebellar peduncle, the middle cerebellar peduncle, and the quadrangular lobule of the cerebellum. RESULTS: Postoperatively, there was no apparent aggravation of neurological symptoms. The main advantage of the approach was that the operation can be performed with a wide horizontal view without sacrificing the deep veins. CONCLUSIONS: It is concluded that lesions in the superior and inferior colliculus, superior and middle cerebellar peduncles, and quadrangular lobules of the cerebellum can be safely operated on with this approach.

Adult↗

PubMed1997

Risk factors and the effect of interferon therapy in the development of hepatocellular carcinoma: a multivariate analysis in 343 patients.

The aims of the present study were to clarify the risk factors for the development of hepatocellular carcinoma (HCC) in chronic hepatitis C virus (HCV) infection and to investigate the effectiveness of interferon (IFN) therapy. We retrospectively studied 343 patients who had been admitted to our hospital; 161 with chronic hepatitis, 49 with liver cirrhosis, 42 with chronic hepatitis bearing HCC and 91 with liver cirrhosis bearing HCC. The mean (+/- SD) observation period was 41.6 +/- 31.1 months. The mean age of HCC and non-HCC patients was 63.5 +/- 7.6 and 56.9 +/- 12.5 years, respectively (P < 0.001). The HCV genotype II (1b) was the most prevalent genotype (92.5%) in HCC patients and the mean age was higher among patients with this genotype (63.6 +/- 7.7 years). Multivariate analysis identified age (P < 0.001), the male gender (P < 0.01), HCV genotype II (1b) (P < 0.05) and excessive alcohol intake (P < 0.05) as independent factors associated with the development of HCC. There was no relationship between the development of HCC and serum HCV levels as quantified by branched DNA assay or competitive reverse transcription polymerase chain reaction. The incidence of HCC in patients who had not received IFN therapy was 10.4/100 person-year, while that of patients who had received IFN therapy was 1.2/100 person-year (P < 0.01) by the person-year method. The low incidence of HCC in patients treated with IFN suggests that IFN may prevent the development of HCC.

Aged↗

PubMed1997

The activation of the JAK2/STAT5 pathway is commonly involved in signaling through the human IL-5 receptor.

The JAK (Janus kinase) family of protein tyrosine kinases and the STATs (signal transducers and activators of transcription) have been shown to be activated in response to a number of cytokines and growth factors. In this study, we evaluated the activation of JAK/STAT pathway upon human interleukin-5 (hIL-5) stimulation of two different hIL-5-responsive cell lines, hIL-5 receptor alpha-subunit (hIL-5R alpha) cDNA-transfected TF-1 (TF-h5R alpha) and butyric-acid-treated YY-1 (YY-Bu), and peripheral eosinophils. Immunoprecipitation and electrophoretic mobility shift analysis revealed that tyrosine phosphorylation of JAK2 and activation of STAT5 were induced upon stimulation with hIL-5 in all three cell types, while STAT1 activation was only observed in eosinophils. These results indicate that JAK2/STAT5 activation is a common JAK/STAT pathway for hIL-5-mediated signal in these cells.

Cell Line↗

PubMed1997

Effect of phenylboronic acid groups in copolymers on endothelial cell differentiation into capillary structures.

Copolymers (IABb) composed of N-isopropylacrylamide (I), N-(3-dimethylaminopropyl)-acrylamide (A), 3-acrylamidophenylboronic acid (B), and a hydrophobic comonomer, n-butyl methacrylate (b), were synthesized as cell culture substrata since we previously learned that bovine aortic endothelial cells (BAECs) cultured on the phenylboronic acid-containing copolymer (IAB) differentiated into capillary structures after 26 days culture. The synthesized IABb copo ymers contained higher boron and amine moieties than the IAB copolymer. The results of the dynamic contact angle measurement revealed that IABb copolymer-coated surfaces showed a relatively hydrophobic nature, changing to hydrophilic in response to the aqueous environment. BAECs cultured on the copolymer substrata developed into capillary networks after 7 days. This is probably due to the enrichment of boron and amine segments in the vicinity of the hydrophilic copolymer surface, enhancing more pronounced interaction of boronates with cell membrane glycocalyx. The introduction of n-butyl methacrylate into the polymers might enhance the diffusion of the hydrophobic segments to the bulk polymers and the concentration of relatively hydrophilic segments at the outermost polymer surfaces by contact with water. A copolymer (IAP) without boronic acid groups was also prepared using N-phenylacrylamide (P) as a comonomer instead of 3-acrylamidophenylboronic acid in the IAB copolymer to investigate the effect of boronic acid moieties on the capillary formation of the cultured cells. Although the endothelial cells seeded on the copolymer without boronic acid groups adhered during the early culture period, these cells showed neither proliferation nor differentiation and detached from the surface after 13 days. These results strongly support the opinion that the phenylboronic acid groups in the copolymers are responsible for the specific induction of tissue formation of BAECs through the interaction with glycoconjugates on the cell membranes.

Acrylamides↗

PubMed1997

Selective extradural anterior clinoidectomy for supra- and parasellar processes. Technical note.

Removal of the anterior clinoid process (ACP) facilitates radical removal of tumors or radical neck clipping of aneurysms in the supra- and parasellar regions by providing a wide operative exposure of the internal carotid artery (ICA) and the optic nerve and by reducing the need for brain retraction. Over a period of 3 years, anterior clinoidectomy was performed in 40 patients, 30 of whom harbored aneurysms (18 of the ICA and 13 of the basilar artery [one patient had two aneurysms]) and 10 of whom had tumors (four large pituitary tumors, four craniopharyngiomas, and two sphenoid ridge meningiomas). The ACP was removed extradurally in 31 cases and intradurally in nine cases. Extradural clinoidectomy was performed in all cases of pituitary adenoma and craniopharyngioma and in most cases of basilar artery aneurysm. Intradural clinoidectomy was performed in two cases of ICA-ophthalmic artery aneurysm, two cases of ICA-posterior communicating artery aneurysm, two cases of ICA cavernous aneurysm, one case of basilar artery aneurysm, and two cases of sphenoid ridge meningioma. The outcome was satisfactory in all patients, except for one patient who underwent clipping of a basilar tip aneurysm and suffered a thalamic and midbrain infarction. Three patients who underwent extradural clinoidectomy suffered a postoperative diminution of visual acuity or a visual field defect on the side of the clinoidectomy. These deficits may have been caused either by drilling of the ACP or by other operative manipulation of the optic nerve. Cerebrospinal fluid rhinorrhea, which required reoperation, occurred in one patient. The authors' experience suggests that the extradural technique of ACP removal is easier and less time consuming than the intradural one and provides better operative exposure. It can be used routinely in treating lesions in the supra- and parasellar regions.

Adenoma↗