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Biomedical subjects

H Obata

Publications and source records attributed to H Obata.

At least 109 records · Page 6Linked to original sources

[Quantitative analyses of glycosaminoglycans in tear fluids in normal human eyes and eyes with corneal epithelial disorders].

The existence and pathophysiological role of glycosaminoglycans in the tear fluid in humans was investigated using quantitative analyses of hyaluronic acid and chondroitin sulfate in the tear fluid. The subjects were 42 eyes of 31 normal controls, 9 eyes of 9 patients with superficial punctate keratitis (SPK), and 13 eyes of 13 patients with epithelial defect. After an instillation of 100 microliters saline solution in the conjunctival sac, as much tear fluid as possible was collected from the lower cul-de-sac. The glycosaminoglycans in the tears were then treated with chondroitinase ABC to make fractions of unsaturated disaccharides. The quantities of disaccharides were determined by high-performance liquid chromatography. Concentrations were expressed as nanomoles of unsaturated disaccharides per protein in the tears. The concentrations of hyaluronic acid and chondroitin sulfate in the normal controls were 0.07 +/- 0.12(n mol/mg protein) and 6.91 +/- 3.63 (n mol/mg protein), respectively. The mean concentration of hyaluronic acid was significantly higher in patients with epithelial erosion than in normal controls, whereas the mean concentration of chondroitin sulfate was significantly lower in patients with epithelial erosion than in normal controls. There was no significant difference in the concentration of glycosaminoglycans between the patients with SPK and normal controls. The results of our study suggest that glycosaminoglycans are synthesized and endogenously secreted into the tear fluids and, especially in the case of hyaluronic acid, may play an important role in corneal epithelial wound healing in patients with epithelial erosion.

Adult↗

[Experimental studies on influence of alignment errors on measurement in a corneal topographic system--relationship between degree of measurement error and working distance].

To evaluate the influence of alignment errors in focusing on the results of measurements in corneal topography, we experimented using polymethyl-methacrylate balls with definite radii of curvature as test objects. We used 3 different corneal topographic systems with different working distances to clarify the relationship between the degree of errors and the working distance. We determined the refractive power of the test balls by the topographic systems and studied changes in the values as the balls were slightly displaced from the alignment position axially, or horizontally. The test balls were set on the stage with a micrometer so that the distance of displacement could be determined precisely. When the test balls were placed precisely in alignment, there was no significant relationship in the magnitude of measurement errors with working distance of the topographical systems. When the test balls were displaced axially, the measurement values decreased as the balls come near from the alignment position and increased as they moved away from the alignment position. The magnitude of the measurement errors caused by back and forth displacement of the object became larger as the working distance of the topographic system became shorter. There was no specific relationship between the degree of measurement errors and the working distance when the balls were displaced horizontally.

Cornea↗

[Effects of blowing or aspiration on ablation rate by excimer laser].

Accurate calibration of ablation rate by excimer laser prerequisite for precise photorefractive keratectomy (PRK). When a polymethylmethacrylate (PMMA) plate is ablated by excimer laser, debris is generated, which may affect homogeneity of the laser beam and energy density, and change the ablation rate. In order to clarify the effects of the debris on the ablation rate, we studied the changes in the ablation rate when the debris was removed by blowing or aspirating over the ablation area during PRK.PMMA plates were ablated using a scanning excimer laser system (EC-5000, NIDEK, Japan) in PRK mode under the following conditions: (1) with air blowing over the ablation area, (2) with aspiration of the debris, and (3) without treatment. The ablation rates were determined by measuring the refractive power of PMMA plates with a lens meter. The ablated surface was observed by scanning electron microscope (SEM). The ablation rate with blowing was the highest among the three conditions, that with aspiration was the second, and that without treatment was the lowest. The ablation rates with blowing showed no significant change when the ablation rates were changed. However, the ablation rates with aspiration or without treatment decreased as the pulse rate increased. The surface ablated during blowing was the smoothest in SEM photographs. We concluded that calibration of the ablation rate using PMMA plates must be done with appropriate air blowing.

Calibration↗

[Alterations of the brain stem and mid-latency evoked potentials under oxygen-nitrous oxide-sevoflurane anesthesia].

We evaluated the alterations of the brain stem and mid-latency evoked potentials (BAEP and MLAEP) in 10-patients who were scheduled for elective abdominal surgery under oxygen-nitrous oxide-sevoflurane anesthesia. With oxygen 2 l.min-1 and nitrous oxide 4 l.min-1, we measured the latency of BAEP and MLAEP at the end-expired sevoflurane concentrations of 0%, 0.3%, 0.6%, 1.0%, 1.5% and 2.0%, respectively. The latency of BAEP was slightly prolonged with oxygen-nitrous oxide-sevoflurane anesthesia. The latency of MLAEP was markedly prolonged with the increase of sevoflurane concentration, and all waves but Na wave disappeared at the 2.0% sevoflurane concentration.

Abdomen↗

Changes in urinary kallikrein excretion and plasma natriuretic factor in a patient with primary aldosteronism with special reference to adrenal histology.

High level of urinary kallikrein excretion was observed in a 23-year-old man with primary aldosteronism. Unilateral adrenalectomy improved the clinical symptoms and normalized the urinary concentration of this vasoactive substance. Although plasma atrial natriuretic factor was not elevated, adrenal surgery lowered its concentration. Coexistence of an adrenal adenoma and lesions of nodular hyperplasia were detected in the removed adrenal gland. We summarize the clinical data of this patient and review the literature.

Adrenal Cortex↗

[Contamination of healthy livestock with verocytotoxin producing Escherichia coli (VTEC), the first isolation from goats in Japan].

As part of the investigation on the source and route of infection with Verocytotoxin producing Escherichia coli (VTEC) in human beings, isolation of VTEC was attempted using fresh feces collected from healthy livestock (cattle, swine and goat) raised in Sagamihra, Yokohama and Hiratsuka cities from October, 1991 to March, 1992. VTEC could be isolated from 1 (1.0%) of 105 swine, 2 (3.6%) of 55 cattle and 2 (15.4%) of 13 goats. VTEC was isolated for the first time from goats in Japan. The combinations of the serotype and toxin type of the isolated strains were O116:H21 (VT2) and O163:H19 (VT2) for those isolated from the cattle, OUT:H19 (VT2vp) for that from the swine and OUT:H21 (VT1) for those from the goats. Since VTEC isolated from the cattle and goats were found to produce VT of the same serotypes as human VTEC, domestic animals were considered to be involved as a source of VTEC infection in human beings.

Animals↗

Guinea pig asthma induced by red soft coral (Dendronephthya nipponica) inhalation.

Spiny lobster fishermen on the Pacific coast of Miyazaki Prefecture in Japan develop bronchial asthma due to occupational sensitization to red soft coral (Dendronephthya nipponica). To assess the role of sensitization in the development of bronchial hyperresponsiveness and the relationship between bronchial responsiveness and bronchial inflammation, we established a guinea pig model of red soft coral induced asthma. Twenty-four guinea pigs were intramuscularly immunized with a priming dose of red soft coral, 5 OD280 (15 mg protein) per 0.5 ml, and 0.5 ml complete Freund's adjuvant on day 1. Booster doses were repeated on day 15. By day 43 all sensitized animals showed high hemagglutination titers against red soft coral conjugated sheep erythrocytes and high IgG1 titers by passive cutaneous anaphylaxis. On day 43, the animals were challenged by inhalation of red soft coral extracts, 20 OD280 for 30 min. The respiratory resistance was monitored by the oscillation method. The respiratory resistance increased immediately upon inhalation in all sensitized animals and returned to baseline within 4 h. The bronchial reactivity to acetylcholine, measured 6 h after red soft coral inhalation in the sensitized animals when the respiratory resistance was returned to baseline, increased significantly (p < 0.05) as compared with the values measured 24 h before inhalation. The acetylcholine response measured 30 h later did not differ from preinhalation levels. There was a significant difference in the number of eosinophils (p < 0.001) in lamina propria and epithelium and of lymphocytes (p < 0.05) in the lamina propria 6 h after inhalation in the sensitized animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗

Cloning and sequencing of an ice nucleation active gene of Erwinia uredovora.

An ice nucleation activity gene, named inaU, of the bacterium Erwinia uredovora KUIN-3 has been sequenced. This gene encodes a protein of 1034 amino acid residues, and its expression product, inaU protein, has an 832-amino acid residue segment consisting of 52 repeats of closely related 16-amino acid motifs (R-domain), flanked by N- and C-terminal sequences (N- and C-domains, respectively). The primary structure of the inaU protein is similar to those of the inaA, inaW, and inaZ gene products of Erwinia ananas, Pseudomonas fluorescens, and Pseudomonas syringae, respectively, but is smaller than any of these products in terms of the size of the R-domain.

Amino Acid Sequence↗

[Quantitative analysis of glycosaminoglycans in tear fluids during corneal epithelial wound healing in rabbits].

We performed quantitative analyses of glycosaminoglycans in the tear fluids in a rabbit wound healing model. We ablated rabbit corneal epithelium with trephine and spatula, and sampled tear fluids before the epithelial ablation, and at 3, 24, 48, and 72 hours after it. After an instillation of 200 microliters saline solution in the conjunctival sac, as much tear fluid as possible was collected from the lower cul-del-sac. The glycosaminoglycans in the tears were then treated with chondoroitinase ABC to make fractions of disaccharides. The quantities of disaccharides were determined with high-performance liquid chromatography as weight per unit protein in the tears. The concentrations of delta Di-HA in the tear fluids at 3 and 24 hours were significantly higher than those before the treatment and returned to the initial value at 72 hours after making the epithelial wound. Among the disaccharides of chondroitin sulfate, delta Di-0S and delta Di-6S showed a significant increase at 3 hours after the treatment but delta Di-4S did not show any significant variation. The results suggest that the glycosaminoglycans in the rabbit tear fluids may play an important role in the corneal epithelial wound healing process.

Animals↗

[Early cytomegalovirus retinitis].

We report the clinical course of cytomegalovirus (CMV) retinitis associated with acquired immunodeficiency syndrome (AIDS) from the initial onset. The patient was a 40-year-old human immunodeficiency virus antibody-positive male with hemophilia A. He was diagnosed as having AIDS on the basis of pneumocystis carinii pneumonia. Ophthalmoscopic examination disclosed a small white punctate lesion at the macular area in his right eye. Because the lesion enlarged gradually with hemorrhages, it was suspected to be CMV retinitis. However, further examination was impossible due to his severe general condition. He died five months later and the autopsy disclosed disseminated CMV infection. Ocular histopathological examination revealed CMV retinitis. The earliest sign of CMV retinitis is supposed to be a white punctate retinal lesion, which becomes a small white patchy lesion resembling a cotton-wool spot. It may gradually progress to diffuse retinal involvement, frequently associated with hemorrhages.

Acquired Immunodeficiency Syndrome↗

Effect of long-term therapy with nipradilol on esophageal varices in patients with compensated cirrhosis. Results of a multicenter open study.

The effect of long-term administration of nipradilol (NIP, Hypadil Kowa, CAS 81486-22-8), a beta-blocker with a vasodilatory action, on esophageal varices was studied in 66 patients with compensated liver cirrhosis. Administration of NIP (6-12 mg/d) for 3-12 months produced progressive improvement of endoscopic findings over time (30% for C, 25% for F, and 40% for the R-C sign after 12 months). At the last examination (mean: 9 +/- 4 months), the improvement rates were 16.7%, 16.7% and 22.7%, respectively. No significant relationship was found between endoscopic improvement and the Child-Pugh score or the dose of NIP. Gastrointestinal bleeding occurred in five patients: one had bleeding esophageal varices, three had bleeding gastric varices, and one had a bleeding gastric ulcer. The systolic blood pressure was decreased significantly (4.6-12.3%) at 2 weeks as well as 1 and 2 months, and the heart rate showed a significant decrease throughout the study (10-18.4%). With the exception of the patients who had gastrointestinal bleeding, no symptoms of decompensation appeared, and there was no deterioration of laboratory parameters including ammonia. Adverse effects occurred in about 10% of the patients, most of which were related to bradycardia and/or hypotension, and they improved when the drug was withdrawn or the dose reduced. These results suggest that long-term administration of NIP is useful in the treatment of esophageal varices.

Adult↗

[201Tl scintigraphic evaluation of tumor mass and viability of bone and soft-tissue tumors].

To characterize 201Tl uptake in patients with bone and soft-tissue tumor, we studied 49 patients with surgically proven tumors and one patient with a tumor diagnosed arteriographically. In 37 of our 50 patients, the tumor was evaluated with 201Tl and arteriography. Moreover, in 14 of patients with pre-operative chemotherapy, pathologic changes were graded on the basis of percent tumor necrosis as defined histologically. The percent tumor necrosis histologically was compared with changes in the scintigraphic and conventional angiographic studies. Radiologic comparisons demonstrated a high degree of correlation with images of 201Tl and both arterial and blood pool phase of 99mTc-HMDP. Ninety-six percent of 28 malignant tumors had positive 201Tl uptake. None of the patients showed any thallium accumulation in the soft tissues or skeleton adjacent to the lesion. Activity of 201Tl was mainly dependent upon a tumor blood flow and a vascular density. In of 14 cases with the preoperative chemotherapeutic treatment, 201Tl scintigraphic changes showed concordance with % tumor necrosis. Thallium-201 was superior to 99mTc-HMDP in predicting tumor response to chemotherapy. Interestingly, delayed images of 99mTc-HMDP of 5 responders with > 90% tumor necrosis showed decreased uptake in the adjacent bone to the tumor mass lesions. It seems to be quite all right to consider that a major determinant of 201Tl uptake is intratumoral angiogenecity, which is closely connected with tumor viability. Therefore, 201Tl is a sensitive radiopharmaceutical for detection of vascular rich bone and soft-tissue tumors, and appears to be a simple and an accurate test for evaluating the response to specific therapeutic regimens of malignant bone and soft-tissue tumors.

Adolescent↗

[Histopathological study of the meibomian glands in 72 autopsy cases].

We investigated histopathological changes in human meibomian glands and analyzed the incidence of histopathological parameters and the relationship between parameters and age or sex of patients. Human meibomian glands, measuring 3 x 3 mm in size, were excised from both upper eyelids of 72 autopsy cases (mean age 63 +/- 12 years; 44 males, 28 females). The specimens were stained with hematoxylin and eosin and examined in detail with the light microscope. The following histopathological changes were investigated as parameters: (1) cystic dilatation of the duct and/or the acini, (2) atrophy of the acini, and (3) granulomatous inflammation. The incidences of the parameters were (1) 34.7% (25 cases), (2) 19.4% (14 cases), and (3) 18.6% (13 cases). There was statistically significant correlation between age and atrophy of the acini, which was found in the older patients. No sex difference was found in any of the parameters. These results suggest that the decrease in the meibomian gland secretion with aging is related to atrophy of the acini. These results further suggest that cystic dilatation, which has been described as a histopathological finding in meibomian gland dysfunction, may be caused by factors other than aging.

Adolescent↗

Electron microscopic observation of pseudopodia from choriocapillary endothelium.

The choriocapillary endothelial cells project pseudopodia-like processes (pseudopodia) through defects in the basement membrane in eyes without any insult or new vessel formation. The ultrastructure of these pseudopodia was observed by transmission and scanning electron microscopy. The pseudopodia contained microfilaments, ribosome-like organella, and/or endoplasmic reticulum-like organella; about half of the pseudopodia contained bundles of microfilaments, and 10% of these contained cytoplasmic organella. The frequency of pseudopodia was not correlated with age, sex, racial difference, location in ocular fundus, or age-related changes in Bruch's membrane. The results of this study did not reveal a relationship between pseudopodia and subretinal new vessel formation. Pseudopodia oriented toward the retinal pigment epithelium (RPE) were significantly more frequent than those oriented toward the choroid or projecting from the lateral side of the choriocapillaris, which suggests a close relationship between the pseudopodia and the function of the RPE.

Adolescent↗