Biomedical subjects

N Ono

Publications and source records attributed to N Ono.

At least 109 records · Page 6Linked to original sources

PubMed1995

Characterization of chitin synthase 2 of Saccharomyces cerevisiae. Implication of two highly conserved domains as possible catalytic sites.

Chitin synthase 2 of Saccharomyces cerevisiae was characterized by means of site-directed mutagenesis and subsequent expression of the mutant enzymes in yeast cells. Chitin synthase 2 shares a region whose sequence is highly conserved in all chitin synthases. Substitutions of conserved amino acids in this region with alanine (alanine scanning) identified two domains in which any conserved amino acid could not be replaced by alanine to retain enzyme activity. These two domains contained unique sequences, Glu561-Asp562-Arg563 and Gln601-Arg602-Arg603-Arg604-Trp605, that were conserved in all types of chitin synthases. Glu561 or arginine at 563, 602, and 603 could be substituted by glutamic acid and lysine, respectively, without significant loss of enzyme activity. However, even conservative substitutions of Asp562 with glutamic acid, Gln601 with asparagine, Arg604 with lysine, or Trp605 with tyrosine drastically decreased the activity, but did not affect apparent Km values for the substrate significantly. In addition to these amino acids, Asp441 was also found in all chitin synthase. The mutant harboring a glutamic acid substitution for Asp441 severely lost activity, but it showed a similar apparent Km value for the substrate. Amounts of the mutant enzymes in total membranes were more or less the same as found in the wild type. Furthermore, Asp441, Asp562, Gln601, Arg604, and Trp605 are completely conserved in other proteins possessing N-acetylglucosaminyltransferase activity such as NodC proteins of Rhizobium bacterias. These results suggest that Asp441, Asp562, Gln601, Arg604, and Trp605 are located in the active pocket and that they function as the catalytic residues of the enzyme.

Amino Acid Sequence↗

PubMed1995

Calcified astrocytoma of the amygdalo-hippocampal region in children.

Three pediatric cases of temporal lobe seizure due to calcified glioma of amygdalo-hippocampal region are described. Computed tomography and magnetic resonance imaging showed dense calcification with no postcontrast enhancement in the amygdalo-hippocampal region. Positron emission tomography showed low oxygen metabolism, low glucose metabolism, hypermetabolism of amino acids, and low regional cerebral blood flow in the tumors. Single photon emission computed tomography showed a high accumulation of 201Tl chloride and 123I-isopropyl iodoamphetamine in one tumor, but otherwise low radioisotope uptake. These studies indicated low-grade malignancies. The patients were treated by partial tumor removal and radiotherapy. Histological examination of the tumor specimens showed astrocytoma with interstitial calcification. One patient died due to tumor recurrence, while the others are doing well with minimal seizure. We recommended temporal lobectomy in similar cases to achieve complete remission.

Adolescent↗

PubMed1995

Influences of beta-blocking agents on cardiovascular actions induced by endothelin-3 administered intracerebroventricularly in anesthetized rats.

Possible involvement that the pressor and positive chronotropic effects of endothelin-3 (ET-3) administered intracerebroventricularly (i.c.v.) participate in the central beta-adrenoceptor has been studied in urethane anesthetized rats. ET-3 administered i.c.v. at dose of 50 pmol elicited the increase in blood pressure and heart rate over a long duration, but a dose of 30 pmol had a minimal effect. These cardiovascular responses to ET-3 were significantly reduced by intravenous pretreatment with pentolinium, ganglionic blocking agent, and phentolamine, alpha-blocker. Also pressor responses to ET-3 were abolished dose-dependently by i.c.v. pretreatment with propranolol at a dose of 1 mumol, nonselective beta-blocker and ICI 118551, beta 2-selective adrenoceptor blocker, but not by i.c.v. pretreatment with metoprolol, atenolol, beta 1-selective blocker, procaine and phentolamine. These results suggest that ET-3 may play a role in cardiovascular regulation through the activation of the sympathetic nervous system involved in the central beta 2-adrenoceptor system.

Adrenergic beta-Antagonists↗

PubMed1995

Expression of adult T-cell leukemia-derived factor in bronchoalveolar lavage cells after canine lung transplantation.

Lung transplantation is now an accepted therapeutic option for patients with end-stage lung disease, and an early diagnosis of rejection is essential in the management of these patients. Adult T-cell leukemia-derived factor (ADF), known as a human homolog of thioredoxin, has been shown to be induced by a variety of stresses. In this study we examined ADF expression in lung tissues and bronchoalveolar lavage cells after canine lung transplantation to determine whether it could be induced by allogenic stimulations and could be used to diagnose early rejection. Allotransplantations were performed in adult mongrel dogs, and immunosuppression was performed from the day of operation to the fifth postoperative day. No immunosuppressant was given from the sixth to the tenth postoperative days. Animals were put to death on the tenth postoperative day. Bronchoalveolar lavage was performed on the fifth and tenth postoperative days, and the lavage cells and lung tissues were examined immunohistochemically with anti-ADF antibody. The grades of rejection were as follows: grade 1 in two animals, grade 2 in three animals, and grade 3 in two animals. The percentages of ADF high-producer cells in bronchoalveolar lavage cells on the fifth and tenth postoperative days were 4.29% +/- 2.65% and 26.6% +/- 3.99%, respectively (p < 0.01). The percentages of ADF high-producer cells in normal healthy dogs and in those with grade 1, grade 2, and grade 3 rejection were 3.00% +/- 1.64%, 20.5% +/- 9.00%, 25.5% +/- 6.06%, and 34.5% +/- 6.50%, respectively. The percentage in each rejection group was significantly higher than that in normal healthy dogs (p < 0.05). These results suggest that examination of bronchoalveolar lavage cells with ADF staining may be useful in the early diagnosis of rejection.

Animals↗

PubMed1995

Effect of the transmembrane gradient of magnesium and sodium on the regulation of cytosolic free magnesium concentration in human platelets.

1. To clarify the mechanism by which cytosolic free Mg2+ concentrations ([Mg2+]i) are regulated in human platelets, we investigated platelet membrane permeability to Mg2+ by altering extracellular Mg2+ concentrations, and tested the existence of a Na(+)-Mg2+ exchanger by manipulating the transmembrane Na+ gradient. 2. Platelet [Mg2+]i was 421 +/- 52 mumol/l in healthy men. [Mg2+]i remained constant during a 120 min exposure to nominally zero (low) or 5 mmol/l (high) external Mg2+ concentrations. 3. Preincubation of platelets with 10(-4) mol/l ouabain effectively decreased the transmembrane Na+ gradient. The ouabain-induced increase in [Mg2+]i was statistically significant after 30 min of exposure (14.6 +/- 2.0%) and reached 24.6 +/- 4.5% after 60 min. Similarly, the replacement of extracellular Na+ with N-methyl-D-glucamine significantly increased [Mg2+]i by 48.5 +/- 3.9% and 78.8 +/- 12.5%, respectively. 4. These results suggest that [Mg2+]i is well controlled in the presence of large transmembrane Mg2+ concentration gradients, and a Na(+)-Mg2+ exchanger may be involved in the regulation of [Mg2+]i in human platelets.

Blood Platelets↗

PubMed1995

Combination effect of fosfomycin and ofloxacin against Pseudomonas aeruginosa growing in a biofilm.

We examined the combined effect of fosfomycin and ofloxacin against Pseudomonas aeruginosa in biofilms by using an in vitro experimental system with a modified Robbins device. Sessile cells in a mature or immature biofilm, developed on a silicon disk, were used, and an ATP bioluminescence assay was employed to assess antibacterial effects. A synergistic effect of fosfomycin and ofloxacin was clearly detected when concentrations at which each drug independently produced no detectable decrease in the bioactivity of sessile cells were used. Exposure of the cells in a mature biofilm to fosfomycin at concentrations of one-eighth of the MIC to 10 times the MIC (6.25 to 500 micrograms/ml) and ofloxacin at three or 10 times the MIC (18.75 or 62.5 micrograms/ml) resulted in reduction of the bioactivity to 1.5 to 4.5% after 72 h. Young sessile cells in an immature biofilm were more susceptible to this combination therapy. With a combination of fosfomycin at three times the MIC and ofloxacin at three times the MIC, complete eradication was confirmed by both ATP assay and scanning electron microscopy.

Adenosine Triphosphate↗

PubMed1995

Intravenous administration of L-arginine inhibits angiotensin-converting enzyme in humans.

The iv administration of L-arginine, a precursor of endothelium-derived relaxing factor/nitric oxide, is known to decrease blood pressure in humans by its direct vasodilatory effects. The purpose of the present study was to determine whether L-arginine infusion modifies the renin-angiotensin (Ang)-aldosterone system as well as blood pressure and renal hemodynamics. L-Arginine and saline vehicle were iv administered to 10 healthy male subjects in random order on different days. L-Arginine infusion (500 mg/kg over 30 min) decreased mean blood pressure (from 81.2 +/- 2.7 to 74.0 +/- 2.5 mm Hg; P < 0.001) and renal vascular resistance (from 0.085 +/- 0.007 to 0.074 +/- 0.006 mm Hg/mL.min; P < 0.01) and increased heart rate (from 60.3 +/- 2.7 to 69.7 +/- 2.1 beats/min; P < 0.001) and renal plasma flow (from 616.6 +/- 37.8 to 701.0 +/- 49.2 mL/min; P < 0.05). L-Arginine reduced serum Ang-converting enzyme activity (from 10.4 +/- 0.6 to 8.9 +/- 0.5 nmol/mL.min; P < 0.05) and plasma Ang-II (from 19.3 +/- 3.3 to 12.7 +/- 2.8 pg/mL; P < 0.001), but had no effect on PRA or the glomerular filtration rate. The saline vehicle did not alter any of these parameters. The iv administration of L-arginine (endothelium-derived relaxing factor/nitric oxide) may reduce the plasma Ang-II concentration by inhibiting Ang-converting enzyme. The mechanism by which L-arginine infusion decreases blood pressure can be at least in part explained by inhibition of the renin-Ang system.

Adult↗

PubMed1995

Systemic magnesium deficiency disclosed by magnesium loading test in patients with essential hypertension.

The present study was designed to determine whether magnesium (Mg) deficiency is present in patients with essential hypertension. We measured the retention of an intravenously administered Mg load (0.2 mmol/kg MgSO4 over 4 h), and serum and erythrocyte Mg concentrations in 17 inpatients with essential hypertension and in 15 normotensive controls. There was no significant difference between the two groups in erythrocyte Mg concentration (normotensives vs., hypertensives: 2.0 +/- 0.5 vs. 2.1 +/- 0.4 mmol/l cells), serum Mg concentration (normotensives vs. hypertensive: 2.1 +/- 0.2 vs. 2.1 +/- 0.2 mg/dl), or in urinary Mg excretion (normotensives vs. hypertensives: 65.8 +/- 25.5 vs. 73.7 +/- 26.7 mg/day). However, Mg retention was significantly higher in hypertensives than in normotensives (normotensives vs. hypertensives: 31.8 +/- 12.1 vs. 41.9 +/- 13.3%). These results suggest that a systemic Mg deficiency, which is undectectable by serum or erythrocyte Mg determination, may exist in patients with essential hypertension.

Adult↗

PubMed1995

Diagnosis and treatment of brainstem abscess using magnetic resonance imaging and microsurgical aspiration--case report.

A 6-year-old boy presented with a pontine abscess initially misdiagnosed as brainstem glioma, but he deteriorated rapidly and developed new symptoms of respiratory distress. Magnetic resonance (MR) imaging revealed a rapidly growing mass lesion in the pons. Microsurgical evacuation of the abscess via a suboccipital retromastoid approach resulted in neurological improvement and resolution of the lesion on MR images. Brainstem abscess can be successfully treated with early, accurate diagnosis based on MR imaging and appropriate microsurgical and antibiotic management.

Brain Abscess↗

PubMed1995

[A semi-quantitative measurement of glycocalyx and an ATP bioluminescent assay for the analysis of Pseudomonas aeruginosa biofilm].

BACKGROUND: In order to analyze each element of a bacterial biofilm, a semi-quantitative measurement of glycocalyx using toluidine blue and an improved ATP bioluminescence assay were developed. RESULTS: In the toluidine blue assay, a linear correlation was obtained between optical density and the amount of gellan gum, which is an exopolysaccharide derived from Pseudomonas elodea. By using the improved ATP assay, ATP at concentration of 1 x 10(-4) mol/l or floating bacterial cells of 10(3) cfu could be detected. The applicability of these two methods was examined in evaluating a total amount of glycocalyx and ATP content of Pseudomonas aeruginosa biofilms, which were developed or treated with antimicrobial agents in a modified Robbins device. CONCLUSION: The changes in optical density and ATP luminescence were reasonable, and well correlated with those obtained by scanning electron microscopy. These results indicate that the toluidine blue assay and ATP assay are useful in analyzing bacterial biofilms.

Adenosine Triphosphate↗

PubMed1995

[Treatment of refractory hypoxemia due to right-to-left interatrial shunt complicating right ventricular infarction: successful short-term percutaneous catheter closure of the patent foramen ovale].

Refractory hypoxemia as a complication of right ventricular infarction is rare. A 74-year-old man developed persistent hypoxemia due to right-to-left interatrial shunting through a patent foramen ovale during the acute phase of right ventricular infarction. Short-term percutaneous transvenous closure of the patent foramen ovale with a large balloon occlusion catheter was life-saving.

Aged↗

PubMed1995

Assessment of platelet cytosolic concentration of free magnesium in healthy subjects.

We measured basal cytosolic concentration of free Mg2+ ([Mg2+]i) in platelets from 30 healthy volunteers by using mag-fura-2, a new fluorescent Mg2+ indicator. The mean [Mg2+]i was 381 +/- 22 mumol/L, with values ranging from 226 to 771 mumol/L. The day-to-day intrasubject coefficient of variation was relatively small (3.6%). [Mg2+]i was significantly higher in men than in women (430 +/- 38 vs 332 +/- 17 mumol/L, p < 0.03), and was not correlated with age. There was no significant relation between platelet [Mg2+]i and serum total Mg concentration. The results indicate that the gender but not age may decide intracellular Mg2+ status. In addition, the mechanisms that regulate [Mg2+]i may be independent of those that influence the extracellular concentration of Mg.

Adult↗

PubMed1995

Hypothalamic hamartoma: anatomic, immunohistochemical and ultrastructural features.

Four patients with hypothalamic hamartoma were examined by CT and/or MR imaging, immunohistochemistry and electron microscopy. The hamartomas arose from the hypothalamus and extended inferiorly. LH-RH neurons were detected in three cases by immunohistochemistry. Electron microscopy revealed large myelinated axons, axon terminals containing dense-core vesicles and axon terminals with clear vesicles forming asymmetrical synapses. The development of hypothalamic hamartoma and its functional manifestations (precocious puberty and laugh attacks) are discussed in reference to the migration of LH-RH neurons from the olfactory placode.

Axons↗

PubMed1994

Long-term follow-up study of conventional irradiation for brain tumours in children: a role for radiosurgery.

21 younger patients (less than 10 years of age) with brain tumours, treated by conventional irradiation, were followed 5 to 20 years (mean 12), using CT scan and/or MR imaging, in order to evaluate adverse effects on the developing brain. Pathological changes such as brain atrophy, lesions in the white matter, calcifications in the brain, and angiopathy were observed in 13 (62%) out of 21 cases. The incidence of abnormalities was related to the age at treatment and the follow-up period. All six cases treated at or under 5 years old and followed more than 10 years showed pathological changes in the brain. In order to minimize the radiation damage, 5 patients with brain tumours less than 5 years old were treated by gamma knife surgery. The early results encourage further trials. Radiosurgery may play a role as an alternative treatment or as a component of future multidisciplinary treatment for brain tumours is children.

Brain↗

PubMed1994

Radiosensitive craniopharyngiomas: the role of radiosurgery.

Clinical characteristics of radiosensitive craniopharyngiomas and histologically identical tumours were re-evaluated from among 53 patients. There were 9 squamous cell type and 3 mixed type tumours. Early effects of radiosurgery for two recent cases are reported. Radiosurgery may have an important role to play in the treatment of craniopharyngiomas, especially of the squamous cell type.

Adolescent↗

PubMed1994

Right atrial to left atrial shunt through foramen ovale during pneumoperitoneum for laparoscopic cholecystectomy.

A 62-year old female patient in whom paradoxical right atrial to left atrial shunt flow through the foramen ovale was detected by transesophageal echocardiography during pneumoperitoneum for laparoscopic cholecystectomy was reported. This patient had a history of mitral valve replacement with residual tricuspid valve regurgitation. It was considered that the onset of paradoxical interatrial shunting through the foramen ovale might be caused not only by mechanical ventilation with positive end-expiratory pressure but also by pneumoperitoneum, especially in patients with heart disease, even if the intra-abdominal pressure was maintained at 12 mmHg.

Cholecystectomy, Laparoscopic↗

PubMed1994

Small hepatocellular carcinoma with intravascular tumor growth into the right atrium.

A 66-year-old man with ascites and marked edema in the lower extremities was suspected of having secondary Budd-Chiari syndrome due to primary liver cancer, based on imaging diagnosis, i.e., ultrasonography, computed tomography, and inferior venacavogram. At autopsy, an encapsulated small liver cancer was found to have extended into the inferior vena cava and right atrium. There have been few reports of small hepatocellular carcinoma with intravascular tumor growth into the right atrium.

Aged↗

PubMed1994

Laparoscopic deroofing for symptomatic liver cysts: report of a case.

We present herein the case of a 73-year-old woman with symptomatic liver cysts and cholelithiasis for whom successful deroofing of the liver cysts and cholecystectomy were performed via laparoscopy. Histopathological diagnosis of the resected cyst wall and direct observation of the inner surface of the remaining cyst wall confirmed that they were benign biliary cysts. The laparoscopic deroofing of liver cysts is therefore not only an effective means of treatment, but it also facilitates the establishment of an exact differential diagnosis.

Aged↗