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Biomedical subjects

M Kaneko

Publications and source records attributed to M Kaneko.

At least 181 records · Page 10Linked to original sources
PubMed1999

[Kinematic MRI using short TR single shot fast spin echo (SSFSE) in evaluating swallowing].

PURPOSE: To determine the utility of short TR single shot fast spin echo (SSFSE) MR imaging for evaluating swallowing. MATERIALS AND METHODS: Five healthy volunteers underwent kinematic MR imaging of swallowing with a 1.5T MR scanner using the short TR (300 ms) SSFSE sequence. Twenty phases of sagittal sections were acquired within 6 sec, where the temporal resolution was 300 ms. For oral contrast medium, we used prune yogurt juice with Fe added. RESULTS: The image contrast of short TR SSFSE was found to be somewhere like that of T1-weighted images. In all cases, both the buccal and pharyngeal stages of swallowing were successfully depicted. The Fe-added prune yogurt juice performed as a positive contrast medium and helped determine anatomical structures in the buccal stage. CONCLUSION: Short TR (300 ms) SSFSE was useful in evaluating swallowing. The combined use of Fe-added prune yogurt juice was helpful in enhancing the surface of the oropharynx.

Contrast Media↗
PubMed1999

[MR imaging of the gastrointestinal tract with half-Fourier single-shot fast spin echo (SSFSE)].

UNLABELLED: Our objective was to implement a non-invasive magnetic resonance imaging (MRI) technique combined with concentrated milk ingestion for depicting the gastrointestinal (GI) tract and detecting gastrointestinal motility and transit. The half-Fourier SSFSE (single-shot fast spin echo) sequence was optimized on the basis of a phantom study. In order to determine the feasibility of milk ingestion as a substitute for contrast medium, ten human volunteers were examined with SSFSE after two types of liquid ingestion (i.e., milk and water). The snapshot images provided subsecond data acquisition for each coronal plane, allowing visualization of peristalsis in the gastrointestinal tract in an almost real-time fashion, without motion-related image degradation, as would normally be seen using conventional MRI. RESULTS: There was no significant difference between concentrated milk and water in terms of depiction of the upper gastrointestinal tract; however, 10 min and 30 min after ingestion, concentrated milk showed better delineation of the intestine than that observed after water ingestion (p < 0.01). CONCLUSION: MR gastrointestinal imaging is a non-invasive method that allows gastrointestinal depiction as well as analysis of motility and passage. Especially with concentrated milk ingestion, the distal intestines were well depicted with adequate contrast filling and distention.

Adult↗
PubMed1999

[Deficit of language comprehension in a child with semantic-pragmatic disorder--dissociation between the phonemic and semantic processing abilities].

We studied the language comprehension deficit of a 11-year-old child with a semantic-pragmatic disorder. We used an original test battery using abstract nouns common to the tasks of repetition, reading aloud, auditory comprehension and comprehension of written words. Although he could repeat and read aloud words as good as normal controls, he could not choose correct pictures from semantically or phonemically resembling pictures by listening to or reading target words. This test demonstrated the dissociation between his phonemic and semantic processing abilities. An examination of the cerebral blood flow with SPECT suggested that the dysfunction of the left temporal lobe caused the deficit in language comprehension.

Brain↗
PubMed1999

[Snake venoms].

Explore the source record for details and available documents.

Animals↗
PubMed1999

[Clinical evaluation of granisetron (BRL43694) in nausea and vomiting induced by anticancer drugs--pediatrics].

Granisetron has been used widely for the prevention and treatment of nausea and vomiting associated with anticancer drugs in adult patients with cancer. This multi-center open study was conducted to study the efficacy, safety and usefulness of granisetron in children with cancer. Among 166 evaluable patients, the efficacy rate (percentage of "remarkably effective" or "effective") was 84.9% and the usefulness rate (percentage of "extremely useful" or "useful") was 87.3%. No serious adverse effects were observed. As granisetron 40 micrograms/kg had an excellent antiemetic effect and a high degree of safety against nausea and vomiting associated with anticancer drugs, it was shown to be useful for children with cancer.

Adolescent↗
PubMed1999

[Surgical treatment for distal aortic arch aneurysm using stent grafting].

To alleviate the invasiveness of surgical treatment for distal aortic aneurysm or dissection, we have been using a stented graft to replace the distal anastomotic suture of the descending aorta. We also developed a new stent graft implanting method for distal aortic aneurysm or dissection which uses cervical branch bypasses from the ascending aorta and requires no extracorporeal circulation. These new surgical treatments for distal arch aneurysm result in low surgical mortality (3.8%) and low surgical morbidity rates (stroke, 7.7%; respiratory complications, 7.7%; no renal complications). These results indicate that these new graft implanting methods using stent graft should be considered as a less-invasive surgical treatment for distal aortic aneurysm or dissection.

Aged↗
PubMed1999

SM-20302, a nonpeptide GPIIb/IIIa receptor antagonist, exhibits a wide therapeutic window in a newly developed hemorrhage model in mice.

We have developed a gastrointestinal hemorrhage model in mice and thereby assessed the potential risk of bleeding following administration of SM-20302, a nonpeptide GPIIb/IIIa receptor antagonist. First, SM-20302 selectively inhibited the interaction between human platelets and fibrinogen in vitro. Second, SM-20302 dose-dependently inhibited ADP-induced ex vivo platelet aggregation in mice and produced an ED50 value of 0.02 mg/kg. ED50 values of cyclo(RGDT)2, aspirin and ticlopidine were 0.48, 0.74 and 13.3 mg/kg, respectively. Finally, the bleeding risk of SM-20302 was examined in our newly developed hemorrhage model. Gastrointestinal hemorrhage was assessed 24 h later when the antiplatelet agents tested were administered to mice prior to the oral dosing of 0.1 N hydrochloric acid in 90% ethanol. The resulting hemorrhage was classified into three grades, major, minor or no bleeding, primarily based on the criteria used in the TIMI trial. All compounds tested induced gastrointestinal hemorrhage in a dose-dependent manner. Minimum hemorrhagic doses, MHDs, of SM-20302, cyclo (RGDT)2, aspirin and ticlopidine were 3, 3, 1 and 100 mg/kg, respectively. The potential risk of bleeding was assessed by the ratio of MHD to ED50 value. MHD/ED50 values of SM-20302, cyclo(RGDT)2, aspirin and ticlopidine were calculated to be 150, 6.3, 1.4 and 7.5, respectively. These results suggest that this experimental hemorrhage model may be useful for the evaluation of the bleeding complications of antiplatelet agents and that SM-20302 may have a wider therapeutic window than nonspecific integrin inhibitor and conventional antiplatelet agents.

Administration, Oral↗
PubMed1999

Frequency distribution of axon diameters in the left aortic nerve of the rat raised in space--Neurolab Program.

INTRODUCTION: To study development of the aortic baroreflex mechanisms under conditions of microgravity, we carried out the various experiments in the neonate rats aged 25 days raised in microgravity for 16 days (flight: FLT group) in Neurolab program (STS-90, space shuttle Columbia, launch date: Apr 17, '98. Some results of the experiments were already reported. The results of histological examination of the aortic nerve which is the afferent of the aortic baroreflex showed that the number of unmyelinated fibers in FLT was significantly less in than those in two control groups and there was no difference between FLT and each control group in the analysis of myelin. In the present paper, the frequency distribution of axon diameters of the left aortic nerves in FLT was compared to that in two ground control groups to examine the growth of the aortic nerve fibers in space. METHODS: After breeding Sprague-Dawley rats for 16 days in the shuttle in space and in the animal center in the Kennedy space center, a total of 43 deeply anesthetized rats were perfused with 1% parahormaldehyde and 1% glutaraldehyde or 4% parahormaldehyde solution buffered at pH7.4 with 0.12 M phosphate solution. Concerning the control groups, one group was the asynchronous ground control (AGC) group in which the rats were housed in the same cages as those on the shuttle, and the other was the vivarium ground control (VIV) group in which the rats were housed in commercial cages. The cervical region of the left aortic nerve which is a branch of the vagus was cut off and stored in the same fixative as that used for perfusion, and postfixed in the solution of 1% OsO4, for 2 hours within 24 hours after the perfusion. The fixed specimens were embedded in epoxy resin blocks by the usual method for electron microscopy following dehydration. Electron microscopic montages of transverse sections of these nerve trunks were made from the five left aortic nerves in each group. The magnification of the montages was approximately 13400 times. The long and short axes (a and b) of the nerve fibers and the myelin thickness (T) were measured with a caliper and the axon diameters (R were calculated by following formula: R2=[(a-2T)2+(b-2T)2]/2.

Animals↗
PubMed1998

Involvement of voltage-dependent Ca2+ channels in cytosolic Ca2+ increase induced by deprivation of extracellular cations in adrenal chromaffin cells of the guinea pig.

The mechanisms of an increase in cytosolic Ca2+ concentration ([Ca2+]i) due to the removal of extracellular cations were examined using the whole-cell patch-clamp technique in combination with fura-2 microfluorometry in guinea pig adrenal chromaffin cells. Removal of Ca2+ and Mg2+ from sucrose-substituted Na+-free solution (0Ca, 0Mg-sucrose) evoked an increase in [Ca2+]i that was suppressed by the addition of Ca2+, Mg2+ or EGTA extracellularly. When Na+ was replaced by Tris+, NMDG+, Li+, Cs+ or choline+, no comparable increase in [Ca2+]i was evoked in the absence of external Ca2+. In voltage-clamped cells at -60 mV with K+-internal solution, 0Ca, 0Mg-sucrose evoked a transient [Ca2+]i increase concomitant with an outward current. In Cs+-loaded cells, 0Ca, 0Mg-sucrose caused a marked inward current (Iin) accompanied by an increase of [Ca2+]i. Choline+-substituted solution produced only a brief Iin without any increase of [Ca2+]i. Both Iin and [Ca2+]i responses to 0Ca, 0Mg-sucrose occurred with holding potentials more positive than -65 mV. The increase in [Ca2+]i expected from the time-integrated Iin evoked by 0Ca, 0Mg-sucrose was correlated with that in [Ca2+]i measured with fura-2. A voltage-dependent Ca2+ channel (VDC) blocker reversibly suppressed the Iin and [Ca2+]i responses to 0Ca, 0Mg-sucrose. Cyclopiazonic acid, an internal store-emptying agent, did not affect both current and [Ca2+]i responses to 0Ca, 0Mg-sucrose. Brief exposure to external EGTA greatly reduced these responses, suggesting that Ca2+ near and/or bound to the cell membrane plays a role in 0Ca, 0Mg-sucrose-induced responses. In sucrose-substituted solution, current-voltage relations for VDC were shifted to negative potentials by decreasing the external Ca2+. These results suggest that VDC activation, probably due to the change in the surface potentials on the gating mechanism of VDC, is involved in the elevation of [Ca2+]i induced by deprivation of divalent cations from sucrose substituted Na+-free solution in adrenal chromaffin cells.

Animals↗
PubMed1998

CRY, a Drosophila clock and light-regulated cryptochrome, is a major contributor to circadian rhythm resetting and photosensitivity.

Light is a major environmental signal for circadian rhythms. We have identified and analyzed cry, a novel Drosophila cryptochrome gene. All characterized family members are directly photosensitive and include plant blue light photoreceptors. We show that cry transcription is under circadian regulation, influenced by the Drosophila clock genes period, timeless, Clock, and cycle. We also show that cry protein levels are dramatically affected by light exposure. Importantly, circadian photosensitivity is increased in a cry-overexpressing strain. These physiological and genetic data therefore link a specific photoreceptor molecule to circadian rhythmicity. Taken together with the data in the accompanying paper, we propose that CRY is a major Drosophila photoreceptor dedicated to the resetting of circadian rhythms.

ARNTL Transcription Factors↗
PubMed1998

The cryb mutation identifies cryptochrome as a circadian photoreceptor in Drosophila.

A new rhythm mutation was isolated based on its elimination of per-controlled luciferase cycling. Levels of period or timeless clock gene products in the mutant are flat in daily light-dark cycles or constant darkness (although PER and TIM oscillate normally in temperature cycles). Consistent with the fact that light normally suppresses TIM, cryb is an apparent null mutation in a gene encoding Drosophila's version of the blue light receptor cryptochrome. Behaviorally, cryb exhibits poor synchronization to light-dark cycles in genetic backgrounds that cause external blindness or demand several hours of daily rhythm resets, and it shows no response to brief light pulses. cryb flies are rhythmic in constant darkness, correlating with robust PER and TIM cycling in certain pacemaker neurons.

Animals↗
PubMed1998

Outcomes of stent-graft treatment of false lumen in aortic dissection.

BACKGROUND: Stent-graft treatment for aortic disease promises to lead to a less invasive therapy than conventional surgical therapy. However, this treatment has not been established as a therapy for aortic dissection. The aim of this study was to examine the effect of stent-graft treatment of aortic dissection, as measured by follow-up data on entry site closure, clotting in the false lumen, and the outcome of the false lumen from the acute to chronic phase after operation. METHODS AND RESULTS: We used a stent-graft of our own design to close the entry site of aortic dissection in 21 cases: 9 were acute (< 14 days), 8 subacute (< 6 months), and 4 chronic (> 6 months). Nine were type A and 12 were type B. In 15 cases, the stent-graft was inserted through the transverse arch, which had been surgically opened under median sternotomy. In the other 6 cases, the stent-graft was inserted by means of a transcatheter through a femoral artery. Using computed tomographic scans, we followed and examined clot formation in the false lumen and reduction in size of the false lumen at 3 levels: at the level of maximum aortic diameter, at the distal end of the stent-graft, and 50 mm distal to the stent-graft. The entry sites were successfully closed in 19 cases (90.4%); in the remaining 2 (both treated with a transcatheter) there was perigraft leakage into the false lumen. The hospital mortality rate of these stent-graft treatments was 14.3% (3 of 21). At 2 weeks after operation, the false lumen had completely clotted, respectively, in 100%, 77%, and 38% of cases at the 3 measurement levels. Substantial shrinkage (> 50% in diameter) of the false lumen at 6 months after the operation was observed in 72%, 60%, and 38% of cases at the respective levels. Shrinkage of the false lumen was particularly enhanced in patients treated within 6 months from the onset of dissection: The false lumen shrank by > 50% in 93%, 75%, and 50% of patients. CONCLUSIONS: In cases of aortic dissection, the stent-graft is an effective tool for closing the entry site and promoting clot formation in the false lumen and for reducing the size of the false lumen within 6 months of the onset of dissection if the entry site has been closed.

Adult↗
PubMed1998

Effect of glucocorticoids on the mouse methionine adenosyltransferase A1 gene expression, which is regulated by two promoters.

The methionine adenosyltransferase A1 (MATA1) gene encodes the hepatic forms of the enzyme MAT I and III. To determine the molecular mechanisms that regulate MATA1 gene expression, we characterized promoters and the 5'-flanking sequence of MATA1. Transient expression assays demonstrated the presence of two promoters for the MATA1 gene. The p1 promoter is contained in the -57 to -2 nucleotide region, and gives rise to the P1 transcript initiated at +1. The p2 promoter is contained in the -248 to -146 nucleotide region. The -229 to -213 nucleotide region of the MATA1 gene, which contains an Ets-binding-site sequence, was necessary for p2 promoter activity. Sequence analysis of 5'-RACE products indicated that there was a transcript (P2) initiated at -156. The -107 to +145 nucleotide region is missing from the mature P2 transcript, which suggests that the -107 to +145 nucleotide sequence is an intron of the P2 transcript. The p2 promoter may give rise to the P2 transcript. The p1 promoter activity was increased by glucocorticoids, but the p2 promoter activity was not affected by glucocorticoids.

Adrenalectomy↗
PubMed1998

Potential of Escherichia coli GTP cyclohydrolase II for hydrolyzing 8-oxo-dGTP, a mutagenic substrate for DNA synthesis.

MutT protein of Escherichia coli prevents the occurrence of A:T --> C:G transversion by hydrolyzing an oxidized form of dGTP, 8-oxo-7, 8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP), which is produced by active oxygen species. In a search for mutT-related genes, we found that the ribA gene, encoding GTP cyclohydrolase II, is able to reduce the increased level of mutation frequency of the mutT strain to almost the normal level, provided that the gene product is overproduced. Purified preparations of Escherichia coli GTP cyclohydrolase II protein as well as the histidine hexamer-tagged recombinant GTP cyclohydrolase II protein efficiently hydrolyze 8-oxo-dGTP and 8-oxo-GTP, producing 8-oxo-dGMP and 8-oxo-GMP, respectively. dGTP was not hydrolyzed by these preparations. GTP cyclohydrolase II catalyzes conversion of GTP to 2, 5-diamino-6-hydroxy-4-(5-phosphoribosylamino)-pyrimidine, which constitutes the first step for riboflavin synthesis. The Km values for the three types of guanine nucleotides, GTP, 8-oxo-GTP, and 8-oxo-dGTP, were almost the same. In the mutT- background, ribA- cells showed higher spontaneous mutation frequencies as compared with that of ribA+ cells. Thus, GTP cyclohydrolase II, the ribA gene product, has a potential to protect genetic material from the untoward effects of endogenous oxygen radicals.

Base Sequence↗
PubMed1998

Expression cloning and characterization of a novel murine alpha1, 3-fucosyltransferase, mFuc-TIX, that synthesizes the Lewis x (CD15) epitope in brain and kidney.

The 3-fucosyl-N-acetyllactosamine (Lewis x, CD15, SSEA-1) carbohydrate epitope is widely distributed in many tissues and is developmentally expressed in some rodent and human tissues, i.e. brain and lung, and mouse early embryo. In such tissues, the Lewis x epitope is considered to be involved in cell-cell interactions. We isolated a novel mouse alpha1,3-fucosyltransferase gene, named mFuc-TIX, from an adult mouse brain cDNA library using the expression cloning method. On flow cytometric analysis, Namalwa cells transfected stably with the mFuc-TIX gene showed a marked increase in Lewis x epitopes but not sialyl Lewis x epitopes. As seen experiments involving oligosaccharides as acceptor substrates, mFuc-TIX transfers a fucose to lacto-N-neotetraose but not to either alpha2,3-sialyl lacto-N-neotetraose or lacto-N-tetraose. The substrate specificity of mFuc-TIX was similar to that of mouse myeloid-type alpha1,3-fucosyltransferase (mFuc-TIV). The deduced amino acid sequence of mFuc-TIX, consisting of 359 residues, indicated a type II membrane protein and shows low degrees of homology to the previously cloned alpha1,3-fucosyltransferases, i.e. mFuc-TIV (48.4%), mouse Fuc-TVII (39.1%), and human Fuc-TIII (43.0%), at the amino acid sequence level. A phylogenetic tree of the alpha1, 3-fucosyltransferases constructed by the neighbor-joining method showed that mFuc-TIX is quite distant from the other alpha1, 3-fucosyltransferases. Thus, mFuc-TIX does not belong to any subfamilies of known alpha1,3Fuc-Ts. The mFuc-TIX transcript was mainly detected in brain and kidney with the Northern blotting and competitive reverse transcription-polymerase chain reaction methods, whereas the mFuc-TIV transcript was not detected in brain with these methods. On in situ hybridization, the mFuc-TIX transcript was detected in neuronal cells but not in the glial cells including astrocytes. These results strongly indicated that mFuc-TIX participates in the Lewis x synthesis in neurons of the brain and may be developmentally regulated.

Amino Acid Sequence↗