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Biomedical subjects

H Ishida

Publications and source records attributed to H Ishida.

At least 253 records · Page 14Linked to original sources
PubMed1999

Vesicular blood flow after ligation of the internal iliac arteries in low anterior resection or abdominoperineal resection.

PURPOSE: Bilateral ligation of the internal iliac arteries has been reported to be a safe procedure in pelvic surgery because there are five collateral pathways. Some of the five pathways are surgically interrupted after resection of the rectum and two cases in which necrosis developed in the perineum were reported. The aim of the study was to assess the degree of safety and blood flow reducing efficacy of internal iliac artery ligation in rectal cancer surgery. METHODS: The subjects were 23 patients with advanced rectal cancer. Tissue blood flow on the surface of the bladder was measured using a laser Doppler flow meter when unilateral or bilateral internal iliac artery were clamped at a central site or at a peripheral site. RESULTS: Tissue blood flow of the bladder before clamping the internal iliac artery was 6 to 74 ml/min/100 g. Blood flow in the right half of the bladder decreased significantly when the right and both internal iliac arteries were clamped (both, P < 0.01), but it did not decrease significantly when only the left internal iliac artery was clamped. The results were the same whether the central site or peripheral site was clamped. When the central site was clamped, there was no difference between the decrease in blood flow in the right half of the bladder whether the right internal iliac artery was clamped or both internal iliac arteries were clamped. By contrast, when the peripheral site was clamped, the decrease in blood flow in the right half of the bladder was much greater when both internal iliac arteries were clamped than when the right internal iliac artery alone was clamped (P < 0.01). The results in the left half were the same as in the right half. Blood flow became 33 to 110 (mean, 73; median, 75) percent of the value before clamping when both internal iliac arteries were clamped at the central site, and 18 to 114 (mean, 52; median, 47) percent when both internal iliac arteries were clamped at the peripheral site. No changes in the color of the bladder or other pelvic organs were observed while the internal iliac arteries were clamped. CONCLUSION: Our study suggests that bilateral internal iliac artery ligation causes a temporary decrease in blood flow to the pelvic organs, but the reduction is not great enough to induce necrosis histologically. We recommend the ligation of the internal iliac arteries at the point below the takeoff of the superior gluteal artery to gain a considerable blood flow reducing effect on the pelvic organs.

Aged↗
PubMed1999

A new simple technique for performing intraoperative endoscopic resection of small-bowel polyps in patients with Peutz-Jeghers syndrome.

We describe herein a simple method for performing intraoperative endoscopic resection of small-bowel polyps associated with Peutz-Jeghers syndrome, using a corrugated anesthetic tube. A 34-year-old man with Peutz-Jeghers syndrome underwent emergency surgery for an ileo-ileo-colic intussusception. A sterile corrugated anesthetic tube was inserted into the small-bowel, proximal to the affected lesion. The small bowel was then telescoped sequentially over the tube using a pleating technique. Consequently, a colonoscope inserted through the tube was easily able to reach the duodeno-jejunal junction, and ten small-bowel polyps were removed using a wire snare and electrocauterization. All resected specimens were washed out by the instillation of saline through a nasogastric tube, then collected on gauze placed near the outlet of the tube. Our technique has the following merits: it is feasible even in emergency surgery; it prevents contamination of the surgical field; and it facilitates the easy collection of polypectomized specimens.

Adult↗
PubMed1999

Peritoneal recurrence of colon cancer detected by positron emission tomography: report of a case.

Increased glucose metabolism has been reported to occur in association with colorectal cancer. As positron emission tomography (PET) using [18F]fluorodeoxyglucose is able to depict hypermetabolic sites, it can therefore be used to detect colorectal cancer. A 69-year-old male patient with a recurrent solitary liver metastasis from colon cancer underwent whole-body PET which revealed high [18F]fluorodeoxyglucose uptake in the lesion. Furthermore, PET revealed peritoneal metastases that had not been detected by conventional imaging methods. Consequently, PET proved useful in helping us to avoid performing unnecessary treatment for the liver metastasis. Although it is uncertain whether early identification of recurrence can prolong survival, it may help to prevent unnecessary treatments being carried out. Thus, the application of PET in carefully selected patients could be beneficial to the management of recurrent colorectal cancer.

Aged↗
PubMed1999

Formation of planar and spiral Ca2+ waves in isolated cardiac myocytes.

A novel Nipkow-type confocal microscope was applied to image spontaneously propagating Ca2+ waves in isolated rat ventricular myocytes by means of fluo-3. The sarcolemma was imaged with di-8-ANEPPS and the nucleus with SYTO 11. Full frame images in different vertical sections were obtained at video frame rate by means of an intensified CCD camera. Three types of Ca2+ waves were identified: spherical waves, planar waves, and spiral waves. Both spherical waves and spiral waves could initiate a planar wave, and planar waves were not influenced by the presence of a nucleus. Spiral waves, however, were consistently found adjacent to a nucleus and displayed a slower propagation rate and slower rate of increase in Ca2+ concentration in the wave front than did spherical and planar waves. The planar waves were apparent throughout the vertical axis of the cell, whereas spiral waves appeared to have a vertical height of approximately 3 microm, less than the maximum thickness of the nucleus (5.0 +/- 0.3 microm). These results provide experimental confirmation of previous modeling studies which predicted an influence of the nucleus on spiral-type Ca2+ waves. When a spontaneous Ca2+ wave is small relative to the size of the nucleus, it appears that the Ca2+ buffering by the nucleus is sufficient to slow the rate of spontaneous propagation of the Ca2+ wave in close proximity to the nucleus. These findings thus support the idea that the nucleus can influence complex behavior of Ca2+ waves in isolated cardiac myocytes.

Aniline Compounds↗
PubMed1999

Structure-function study on a de novo synthetic hydrophobic ion channel.

Ion conduction properties of a de novo synthesized channel, formed from cyclic octa-peptides consisting of four alternate L-alanine (Ala) and N'-acylated 3-aminobenzoic acid (Aba) moieties, were studied in bilayer membranes. The single-channel conductance was 9 pS in symmetrical 500 mM KCl. The channel favored permeation of cations over anions with a permeability ratio (PCl-/PK+) of 0.15. The selectivity sequence among monovalent cations based on permeability ratio (PX+/PK+) fell into an order: NH4+(1.4) > Cs+(1. 1) >/= K+(1.0) > Na+(0.4) >> Li+(0). The conductance-activity relationship of the channel in K+ solutions followed simple Michaelis-Menten kinetics with a half-maximal saturating activity of 8 mM and a maximal conductance of 9 pS. The permeability ratio PNa+/PK+ remained constant ( approximately 0.40) under biionic concentrations from 10 to 500 mM. These results suggests that the channel is a one-ion channel. The pore diameter probed by a set of organic cations was approximately 6 A. The single-channel current was blocked by Ca2+ in a dose-dependent manner that followed a single-site titration curve with a voltage-dependent dissociation constant of 0.6 mM at 100 mV. The electric distance of the binding site for Ca2+ was 0.07 from both entrances of the channel, indicating the presence of two symmetrical binding sites in each vicinity of the channel entrance. Correlations between conduction properties and structural aspects of the channel are discussed in terms of a three-barrier and two-binding-site (3B2S) model of Eyring rate theory. All available structural information supported an idea that the channel was formed from a tail-to-tail associated dimer of the molecule, the pore of which was lined with hydrophobic acyl chains. This is the first report to have made a systematic analysis of ion permeation through a hydrophobic pore.

Binding Sites↗
PubMed1999

Laparoscopic gastropexy for acute gastric volvulus: a case report.

A 7-year-old girl presented with an acute gastric volvulus that was reduced with a nasogastric catheter. An anterior gastropexy was undertaken laparoscopically. The gastrocolic omentum was deficient along most of the greater curvature, which had allowed organoaxial volvulus. Two years later, gastric volvulus has not recurred. Laparoscopy is an acceptable approach for the evaluation and treatment of children with acute gastric volvulus.

Acute Disease↗
PubMed1999

Application of authentic peroxynitrite to biological materials.

A method to expose cultured cardiac myocytes to authentic ONOO- by using a constant perfusion system was described. The perfusion apparatus is linked to a microscope equipped with video and fluorescence measurement systems, which enable the evaluation of myocardial contraction, [Ca2+]i, [pH]i, and membrane fluidity. Special care is needed to adjust the pH of the solution appropriately and to obtain a constant concentration of ONOO-.

Animals↗
PubMed1999

A patient who was found to be pregnant unexpectedly during hysteromyomectomy.

We present a case of an unexpected pregnancy and an ultimately successful obstetric outcome. The patient underwent abdominal myomectomy under spinal anaesthesia for a uterine leiomyoma with menorrhagia and infertility. Later, she was found to have been in the 7th gestational day at the time of surgery. The blastocyst survived the surgical manipulation and anaesthesia, resulting in a successful pregnancy. The literature on the endocrinological stress response during anaesthesia and surgery suggests that spinal anaesthesia administered in this case was potentially helpful in maintaining progesterone levels and avoiding increased prolactin levels; increased prolactin levels might be deleterious to implantation of the blastocyst.

Journal Article↗
PubMed1999

Distinct roles of peroxynitrite and hydroxyl radical in triggering stunned myocardium-like impairment of cardiac myocytes in vitro.

Myocardial stunning is characterized by the impairment of excitation-contraction coupling via a decrease in myofilament Ca2+ responsiveness, thought to be triggered by hydroxyl radicals (*OH) generated upon reperfusion. Since peroxynitrite is also expected to be produced during reperfusion, we examined whether it can induce a stunned myocardium-like impairment of cardiac myocytes. Its effect on cultured cardiac myocytes was compared with that of hydrogen peroxide (H2O2), *OH source. Infusion of peroxynitrite (0.2 mM) induced a decrease in cell motion and a complete arrest in diastole at 2.9 +/- 0.3 min, which coincided with an elevation in [Ca2+]i. Arrest induced by infusion of H2O2 (10 mM) was not associated with an increase in [Ca2+]i. The ATP content was unaffected by peroxynitrite (control, 34.3 +/- 3.4: + peroxynitrite, 32.9 +/- 3.5 nmol/mg protein) and the cells remained viable. Sulfhydryl (SH) content was decreased by peroxynitrite, but not by H2O2. The membrane fluidity (a measure of peroxidation of the membrane lipids) was not affected by peroxynitrite, but was decreased by H2O2. Onset time of arrest was unaffected by deferoxamine (0.2 mM), but was delayed by DTT (10 mM) (from 2.9 +/- 0.3 to 19.2 +/- 1.6 min). Nitrotyrosine content was unchanged by peroxynitrite, and its augmentation with Fe3+/EDTA (1 mM) was not associated with a shortened onset time of arrest. The function of the Na+/Ca2+ exchanger was impaired by peroxynitrite, but not by H2O2. Peroxynitrite and H2O2 each induce arrest, but only the former increases [Ca2+]i. One of the mechanisms of the increase in [Ca2+]i is Na/Ca2+ exchanger dysfunction. The impairments were induced through SH oxidation by peroxynitrite, but through lipid peroxidation by H2O2. Myocardial stunning may be induced by both species in concert.

Adenosine Triphosphate↗
PubMed1999

Total synthesis of a cholinergic neuron-specific ganglioside GT1a alpha: a high affinity ligand for myelin-associated glycoprotein (MAG).

An efficient total synthesis of a cholinergic neuron-specific ganglioside GT1a alpha (IV3NeuAcIII6NeuAcII3NeuAc-GgOse4Cer) is described. The suitably protected sialyl-alpha(2-->6)-gangliotriose (III6NeuAc-GgOse3) derivative was glycosylated with the phenyl 2-thioglycoside of sialic acid in the presence of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethane-sulfonate (TMSOTf) in acetonitrile medium, giving the disialogangliotriose (III6NeuAcII3NeuAc-GgOse3) derivative which contains both sialyl-alpha(2-->6)-GalNAc and sialyl-alpha(2-->3)-Gal structures (Route I). This pentasaccharide was efficiently synthesized also by the coupling of (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2-->6)-2-deoxy-3,4-O-isopropylidene-2-ph thalimido-D-galactopyranosyl trichloroacetimidate with 2-(trimethylsilyl)ethyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2-->3)-(2,6-di-O-benzyl-beta-D-galactopy ranosyl)-(1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, followed by conversion of the phthalimido group to the acetamido group (Route II). O-Deisopropylidenation and further glycosylation with methyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-gala ct-2-nonulopyranosylonate)-(2-->3)-2,4,6-tri-O-benzoyl-1-thio-b eta-D-galactopyranoside, promoted by dimethyl(methylthio)sulfonium triflate (DMTST), gave the desired trisialogangliotetraose (IV3NeuAcIII6NeuAcII3NeuAc-GgOse4) derivative, which was converted stepwise into the title ganglioside GT1a alpha by the introduction of the ceramide part and then complete deprotection. The ganglioside obtained was shown to be identical with the native GT1a alpha on TLC-immunostaining.

Animals↗
PubMed1999

The structural basis for the susceptibility of gangliosides to enzymatic degradation.

The conformational properties of GM2, GalNacbeta-4(Neu5Acalpha-3) Galbeta-4Glcbeta-1Cer have been compared to those of 6'-GM2, in which the linkage between the GalNAc and Gal was altered from GalNacbeta-4Galbeta- to GalNacbeta-6Galbeta-, and to those of GD1a, Neu5Acalpha-3Galbeta-3GalNAcbeta-4(Neu5Acalpha-3 )Galbeta-4Glcbeta-1Cer, and GalNAc-GD1a. Our results revealed that unlike the compact and rigid oligosaccharide head group found in GM2, where the Neu5Ac and the GalNAc residues interact, the sugar chain of 6'-GM2 is in an open spatial arrangement, with the Neu5Ac no longer interacting with GalNAc, freely accessible to external interactions. The structure of GD1a can be regarded as that of GM2 with an extension of the terminal Neu5Acalpha-3Galbeta-disaccharide. The inner portion of GD1a is that of GM2 comprising the very rigid GalNAc-[Neu5Ac-]Gal trisaccharide. The terminal Neu5Ac-Gal linkage is flexible and fluctuates between two limiting conformations. In GalNAc-GD1a the outer sialic acid gains conformational rigidity due to the presence of the outer GalNAc in position 4 of galactose. This ganglioside has two 'core' GalNAc-[Neu5Ac-]Gal trisaccharide linked in tandem.

Carbohydrate Sequence↗
PubMed1999

Long-term follow-up of the changes in circulating cytokines, soluble cytokine receptors, and white blood cell subset counts in patients with rheumatoid arthritis (RA) after monoclonal anti-TNF alpha antibody therapy.

To investigate the mechanism of the long-lasting efficacy of chimeric monoclonal anti-TNFalpha antibody (cA2) therapy for rheumatoid arthritis (RA), eight patients with refractory RA were treated with a single infusion of cA2 and the changes in circulating cytokines (IL-1, IL-6, TNFalpha, and IL-10), soluble cytokine receptors (TNF-RI, RII, and sIL-6R) and peripheral white blood cell (WBC) subset counts were followed up long-term (12 weeks) after cA2 therapy in them. Significant clinical responses (>20% improvement according to Paulus' criteria) were observed just after cA2 infusion and lasted more than 4 weeks in all patients, as reported elsewhere. Moreover, five of the eight patients showed prolonged clinical responses (>12 weeks). The elevated serum IL-6 and sTNF-RI (or RII) levels before treatment rapidly decreased after treatment. The serum IL-10 levels also significantly elevated before treatment. The elevations of serum IL-10 levels were augmented after treatment and stayed higher than the baseline in four patients with prolonged clinical responses. No significant TNFalpha, IL-1alpha and -beta, or sIL-6R were detected in the sera of the patients before treatment and during the whole study period. On the other hand, peripheral lymphocytes as well as total WBC and neutrophils increased for 4 weeks after treatment. However, thereafter, only the lymphocyte count decreased gradually and stayed below the baseline long-term (12 weeks). FACS analysis revealed the predominance of T lymphocytes in the decrease in lymphocyte counts. These results suggest that the augmentation of IL-10 production and the decrease in T cells might partly contribute to the long-lasting efficacy of cA2 treatment in RA.

Adult↗
PubMed1999

Visualization of biphasic Ca2+ diffusion from cytosol to nucleus in contracting adult rat cardiac myocytes with an ultra-fast confocal imaging system.

In contracting cardiac myocytes, the rapid changes in cytosolic and nuclear Ca2+ make it difficult to determine whether the nuclear Ca2+ transient is caused by diffusion from the cytosol or by Ca2+ release channels on the inner nuclear membrane, or both. The propagation mechanism in the nucleoplasm also remains unknown. We have developed an ultra-fast Nipkow confocal imaging system able to acquire two-dimensional images at approximately 4 ms/full frame speed and employed it to analyze Ca2+ waves and the dynamics of the cytosolic and nuclear Ca2+ transients after electrical stimulation of cardiac myocytes. The pattern of nuclear Ca2+ upon stimulation was well described by a mathematical model of Ca2+ diffusion across the nuclear envelope. No evidence of Ca2+ release from perinuclear Ca2+ stores was obtained. The Ca2+ diffusion constant appeared to change during contraction, with essentially free diffusion of Ca2+ through nuclear pore complexes at low cytosolic Ca2+ and partially restricted diffusion at high cytosolic Ca2+. The Ca2+ in the nucleoplasm propagated by diffusion and no Ca2+ release phenomena were seen in the nucleus.

Animals↗
PubMed1999

Structure, evolution, and liver-specific expression of sterol 12alpha-hydroxylase P450 (CYP8B).

The rat CYP8B cDNA encoding sterol 12alpha-hydroxylase was cloned and sequenced. The amino acid sequence of the heme-binding region of CYP8B was close to those of CYP7A (cholesterol 7alpha-hydroxylase) and CYP7B (oxysterol 7alpha-hydroxylase). Molecular phylogenetic analysis suggests that CYP8B and the CYP7 family derive from a common ancestor. The P450s of the CYP7 and CYP8 families, except for CYP8A (prostacyclin synthase), catalyze the oxygenation of sterols from an alpha surface in the middle of the steroid skeleton. These facts suggest that CYP8B is a P450 closely linked to those of the CYP7 family. CYP8B was expressed specifically in liver. Hepatic CYP8B mRNA level and the 12alpha-hydroxylase activity were altered by cholestyramine feeding, starvation, streptozotocin-induced diabetes mellitus, and administration of clofibrate, dexamethasone or thyroxin, indicating the pretranslational regulation of CYP8B expression. The enhanced CYP8B mRNA expression in streptozotocin-induced diabetic rats was significantly decreased by insulin within 3 h of its administration. These facts demonstrate a regulatory role of insulin in CYP8B expression as a suppressor.

Amino Acid Sequence↗