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Biomedical subjects

H Kikuchi

Publications and source records attributed to H Kikuchi.

At least 433 records · Page 24Linked to original sources
PubMed1993

Haemodynamic study of arteriovenous malformations using a hydraulic model.

Despite the accumulation of intraoperative data on arteriovenous malformations (AVMs), details of the haemodynamics have not yet been elucidated. A hydraulic model was constructed from silicone and glass tubes to simulate a high-flow AVM. During stepwise obliteration of the nidus, haemodynamic changes were continuously measured in residual parts of the AVM and in the surrounding brain. The flow in the residual AVM decreased nonlinearly with the advance of obliteration. The feeder pressure increased markedly from 37 mmHg to 94 mmHg, while the drainer pressure decreased gradually. The flow volume in the surrounding brain increased markedly from 40 ml/min to 100 ml/min at an occlusion ratio of 60%, where the pressure gradient across the nidus reached 60 mmHg. In the presence of autoregulation, further obliteration showed no change in the flow volume with the increased pressure gradient to 93.7 mmHg. Under dysautoregulatory conditions the flow volume increased to 122 ml/min, although the pressure gradient was 8.3 mmHg lower than that under autoregulatory conditions. Simulation study is useful in understanding haemodynamic changes during the treatment of AVMs.

Arteriovenous Malformations↗
PubMed1993

Streptomyces subtilisin inhibitor-like proteins are distributed widely in streptomycetes.

Streptomyces subtilisin inhibitor-like proteins were found to be distributed widely in streptomycetes by using the combination of the convenient, newly developed plate assay system and an established liquid culture assay. Almost all the strains formerly categorized as Streptoverticillium species produced proteins that exhibited inhibitory activity against both subtilisin BPN' and trypsin. N-terminal regions of three purified proteins showed high structural similarity to those of other previously reported SIL inhibitors.

Amino Acid Sequence↗
PubMed1993

Comparison of the ability of lactate dehydrogenase-elevating virus and its virion RNA to infect murine leukemia virus-infected or -uninfected cell lines.

Lactate dehydrogenase-elevating virus (LDV) has a strict species specificity. Cells or cell lines other than a particular subset of mouse primary macrophages which can support LDV replication in vitro have not been identified. LDV induces neurological disorders in old C58 or AKR strains, in which the involvement of multiple copies of the endogenous N-tropic murine leukemia virus (MuLV) genome and the Fv-1 locus of the mouse has been implicated. Our previous studies have demonstrated that LDV could infect and replicate in cell lines of the mouse or other species in vitro when they were infected with MuLV. The significance of and the precise mechanism underlying this phenomenon, however, remain unclear. We demonstrated in this study the efficient infection and replication of the virus in vitro by inoculation of its RNA mixed with liposome. No significant difference either in the efficiency of RNA transfection or in the ability to support its replication was observed among the various species' cell lines examined. In addition, by RNA transfection the virus replicated with equal efficiency in MuLV-infected and -uninfected cells or in macrophages derived from mice irrespective of their age. In contrast, the pattern of the infection by virus particles was quite different; LDV replication was observed only in macrophages (particularly from newborn mice) and MuLV-infected cells. By using various LDV isolates, it was demonstrated that the capability of replication between neurovirulent, LDV type C, and the other avirulent strains was almost the same in mouse cell lines when their RNA was introduced into the cells. Higher infectivity of LDV-C to MuLV-infected cells may be due to its efficient incorporation of the particles into MuLV-infected cells.

3T3 Cells↗
PubMed1993

A new approach to the integrity of dual blood-brain barrier functions of global ischemic rats. Barrier and carrier functions.

BACKGROUND AND PURPOSE: We studied the influence of reperfusion on carrier and barrier functions of the blood-brain barrier after transient global ischemia in rats. METHODS: We used iodine-125-labeled 3-iodo-alpha-methyl-L-tyrosine and carbon-14-labeled sucrose as tracers for studying carrier and barrier functions of the blood-brain barrier, respectively. Brain uptakes of these two tracers were measured in Wistar rats subjected to either 15- or 30-minute four-vessel occlusion developed by Pulsinelli and Brierly before recirculation for 3, 6, 24, 48, and 72 hours. Tracer (5 microCi) was injected intravenously in each rat 30 minutes before killing the animal. RESULTS: Following 15- or 30-minute ischemia, [14C]sucrose uptakes were significantly higher at 3 and 6 hours of reperfusion before recovery to control values after reperfusing for 24 to 48 hours in almost all brain regions. However, a rebound in radioligand uptake was significantly manifested in some sites at 72 hours after reperfusion (p < 0.05 to p < 0.01). Uptakes of 125I-3-iodo-alpha-methyl-L-tyrosine were brain site-dependent: significantly (p < 0.05) higher in cortex (3 and 48 hours after reperfusion) and thalamus (3, 6, and 48 hours after reperfusion) but significantly (p < 0.05 to p < 0.01) lower in striatum, cortex (72 hours after reperfusion), and midbrain (6, 24, and 72 hours after reperfusion). Because the [14C]sucrose uptake in brain was 10% lower than that of 125I-3-iodo-alpha-methyl-L-tyrosine, the change in absolute transport of the latter tracer was approximated to its brain uptake. CONCLUSIONS: The carrier and barrier functions of the blood-brain barrier should be evaluated separately. The radioligand 125I-3-iodo-alpha-methyl-L-tyrosine may serve as a useful tool to evaluate the carrier function of the blood-brain barrier after transient cerebral ischemia in rats.

Animals↗
PubMed1993

Glucose consumption in recurrent gliomas.

In order to investigate the clinical significance of glucose consumption (GC) in recurrent gliomas, positron emission tomography with 18F-labeled fluorodeoxyglucose was measured in 18 cases of histologically verified recurrent gliomas. The GC of the tumors were categorized into four groups. Five tumors were in Group IV, the highest GC, four were in Group III, eight were in Group II, and one was in Group I. Masses in Groups III and IV were clearly defined as a hot spot higher than or similar to the GC of the contralateral cortex. Half of the recurrent gliomas showed the lower GC of Group I or II, but two thirds of these were histologically high-grade gliomas. Although GC in the recurrent gliomas did not always increase as expected, a focal increase of GC, even mild and small, in the area of previous surgery is diagnostically important. Tumors with high GC showed high histological malignancy, irrespective of tissue damage. Patients with tumors of low GC had longer survival rates than those with high GC, although statistical significance was not obtained. Thus, positron emission tomography with 18F-labeled fluorodeoxyglucose was useful for detecting the recurrence of gliomas and suggesting their histological malignancy and prognosis. Care should be taken because viable tumor cells could be present in areas of low GC and small recurrent masses could be missed because of the poor spatial resolution of positron emission tomography.

Adult↗
PubMed1993

Regulation of scu-PA secretion and u-PA receptor expression in osteoblast-like cells.

The production of proteolytic enzymes by osteoblasts is considered important for initiating osteoclastic bone resorption. Using the established cell line NY as an example of osteoblast-like cells, the effect of intracellular cyclic AMP (cAMP) and protein kinase C (PKC) on plasminogen activator secretion and its specific binding to the cells were investigated. HT-1080 cells were used as the control. NY cells predominantly secrete single-chain urokinase-type plasminogen activator (scu-PA) and some two-chain u-PA. Both scu-PA and u-PA were present in the cell surface and cell lysate of NY cells, and their distribution in HT-1080 cells was quite similar to that of NY cells. Exposing cells to phorbol myristate acetate (PMA) or dibutyryl cyclic AMP (db cAMP) enhanced the secretion of scu-PA and two-chain u-PA, whereas 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) decreased scu-PA secretion, indicating that it is enhanced by protein kinase C (PKC) as well as by cAMP in NY cells. On the other hand, in HT-1080 cells, PMA decreased the level of two-chain u-PA secretion into the conditioned medium. The binding assay of 125I-DFP-u-PA to NY cells revealed the presence of a single class of binding sites with a Kd of 2.23 nM and Bmax of 0.82 x 10(6) binding sites/cell. PMA however, altered neither the Kd nor the Bmax. Dibutyryl cAMP increased the Bmax 1.9 fold. Thus, NY cells secrete u-PA and express specific binding sites on the cell surface, which are modulated by cAMP and PKC.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic AMP↗
PubMed1993

A study on the values computed by dieticians and chemical analysis of fats, cholesterol, and P/S ratio in food.

Dieticians computed the fat and cholesterol contents of 11 foods that were commercially produced as ready-to-eat food from food component lists and obtained the P/S ratio (polysaturated/saturated fatty acids) from the fatty acid component list. Meanwhile the same foods were diluted and homogenized. The internal standard was combined with hepatadecanoic acid and tricaprin. The samples that had been extracted by the Folch method were analyzed for their lipid content (GC analysis using a HS-SS-10 columns for fatty acids and an OV-1 column for lipid and cholesterol). A significant positive correlation was noted between the results of dieticians' analysis and those obtained from a gas chromatographic analysis of lipid and cholesterol contents and the P/S ratio, proving that lipid analysis of food by dieticians is highly reliable. Therefore for diseases (such as hyperlipemia, arteriosclerosis, obesity, diabetes mellitus, fatty liver, and pancreatitis) in which dietary factors have a significant effect on their clinical course, dietary instructions on dietary fats based on an analysis by dieticians are considered to be effective.

Cholesterol↗
PubMed1993

Clinical experience with expanded polytetrafluoroethylene sheet used as an artificial dura mater.

Dural repair using chemically treated cadaveric dura mater often results in atrophic and fragile change of the substitute as well as adhesion between the dura mater and brain surface at reoperation. Creutz-feldt-Jakob disease has occurred after repair using cadaveric dura mater. Expanded polytetrafluoroethylene (EPTFE) surgical sheet was used for dural repair in 34 patients. Suturing of EPTFE was easy and the incidence of cerebrospinal fluid accumulation in the epidural space was the same as when cadaveric dura mater was used. Six patients underwent reoperation, 1-15 months after the first operation. At reoperation the EPTFE sheet showed no change except for becoming transparent, and the strength was well preserved. A very thin layer of granulation tissue was formed between the EPTFE sheet and brain surface, but the EPTFE sheet was easily detached from the brain surface without adhesion even 15 months after the first operation. Our results suggest that the EPTFE sheet can be used safely and effectively as an artificial dura mater.

Brain Diseases↗
PubMed1993

Role of histocompatibility antigen gene and protooncogene expressions in intracerebral tumorigenicity of mouse neuroblastoma.

The role of N-myc, c-src, and major histocompatibility complex (MHC, H-2 in the mouse) class I antigen gene expressions in dimethyl sulfoxide (DMSO)-induced differentiation and intracerebral tumorigenicity was examined using a mouse MNB85 neuroblastoma cell line. A fluorescence-activated cell sorter disclosed cell-surface MHC enhancement by DMSO, causing an increase in cytotoxic T-lymphocyte sensitivity. Southern blot analysis verified a single copy of the proto-oncogenes and MHC deoxyribonucleic acids in both untreated and DMSO-treated MNB85 cells. Northern blot analysis indicated that DMSO treatment induced a decrease in N-myc and an increase in c-src and MHC messenger ribonucleic acids. Nuclear run-off transcription assay revealed down-regulation of N-myc at a posttranscriptional level, contrasted with primary up-regulation of c-src at a transcriptional level. Immunoprecipitation after treatment with enzyme endo-beta-N-acetyl-glycoseamidase H proved that the terminal glycosylation of MHC heavy-chain gene products normally occurs in the Golgi apparatus of MNB85 cells. Intracerebral tumorigenicity assay showed that cells highly MHC-expressed by DMSO were less tumorigenic than untreated cells in association with DMSO-augmented cytotoxic T-lymphocyte susceptibility. These results suggest that proto-oncogenes may be linked to cellular differentiation, while cell-surface MHC gene expression influences intracerebral immunosurveillance.

Animals↗
PubMed1993

Cerebral revascularization using omental transplantation for childhood moyamoya disease.

Between January, 1986, and October, 1990, 30 children with moyamoya disease, aged from 2 to 17 years, underwent omental transplantation to either the anterior or the posterior cerebral artery territory. The mean follow-up period was 3.8 years, ranging from 1.6 to 6.4 years. Seventeen patients had symptoms of monoparesis, paraparesis, and/or urinary incontinence and were treated using unilateral or bilateral omental transplantation to the anterior cerebral artery territory. Eleven patients had visual symptoms and were treated with unilateral or bilateral omental transplantation to the posterior cerebral artery territory. Two patients had symptoms associated with both the anterior and the posterior cerebral arteries, and were treated with dual omental transplantations. All 19 patients treated with omental transplantation to the anterior cerebral artery and 11 (84.6%) of the 13 treated with omental transplantation to the posterior cerebral artery showed improvement in their neurological state. Patients with more collateral vessels via the omentum had more rapid and complete improvement in their neurological state. Patients with severe preoperative neurological deficits associated with the posterior cerebral artery had persistence of their symptoms.

Adolescent↗
PubMed1993

[A three-dimensional reconstruction of the temporal bone by the helical scanning CT and its clinical application].

The current availability of 3 dimensional (3-D) imaging from Computed Tomography (CT) has yielded new anatomical information and pre-and postoperative evaluations. However, little discussion as to the 3-D structural image of the temporal bone has been reported because conventional CT does provide sufficient data to produce such images. The Helical scanning CT gathers continuous and multiple slice image data since it consists of an X-ray tube that continuously rotates around the patient while the patient moves continuously into the CT scanner. Thus, application of the Helical scanning CT has made it possible to reconstruct 3-D images of the minute and complicated structure of the temporal bone. We evaluated 3-D images from 9 typical cases, examined from February to October 1992. As a result, we found that the 3-D images reconstructed with this system are useful for evaluation of the postoperative state of tympanoplasty, the diagnosis of anomalies of the bony labyrinth, and examining the extent of bone destruction induced by trauma, cholesteatoma, etc.

Adolescent↗
PubMed1993

[Moyamoya disease].

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Arteriosclerosis↗
PubMed1993

[Identification of Mycobacterium tuberculosis complex and Mycobacterium avium-intracellulare complex by using nonisotopic DNA probes].

A total of 31 clinical isolates of mycobacteria consisting of 21 strains of M. avium-intracellulare complex (ten strains each of M. avium and M. intracellulare identified by specific 125I-labeled DNA probes and one strain of M. avium-intracellulare complex identified by conventional biochemical tests) and 10 strains of M. tuberculosis (identified by a specific 125I-labeled DNA probe) were subjected to identification by hybridization protection assay (HPA) with an acridinium-ester (AE) labeled DNA probe. The results thus obtained were in complete agreement with those obtained by 125I-labeled DNA probes (30 strains) or by conventional biochemical tests (one strain). HPA by the AE-labeled DNA probe is safe, simple and rapid, and can be done with ease in any clinical laboratory.

DNA Probes↗