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H Obata

Publications and source records attributed to H Obata.

At least 73 records · Page 4Linked to original sources
PubMed1998

High predictive value of red cell volume measurement using carboxy-haemoglobin in a rabbit model of haemorrhage.

We have studied the accuracy of blood volume measurements using carbon monoxide (CO)-labelled haemoglobin (COHb) injection and dilution (CO method) by comparing changes in red cell volume (RCV) measured using the CO method and 51Cr-labelled erythrocyte dilution (51Cr method) in a haemorrhage and infusion model in rabbits. RCV was measured repeatedly using the CO method at four different blood volume stages (stages I-IV). At stages I and IV, RCV was measured simultaneously using the 51Cr method. In comparing the sum of the circulating RCV and extracted RCV (SUM RCV) using the CO method, the values were almost equal and there were no significant differences between the values at the four stages. In comparing circulating RCV measured using the CO method and the 51Cr method, mean difference between the two methods was 0.80 (SD 0.76) ml kg-1 or 4.7 (4.6)%, and a positive correlation was observed (r = 0.91). We conclude that the CO method can be used to measure blood volume during perioperative periods in infants because it avoids use of a radioactive tracer, is simple and repeated measurements are possible.

Animals↗
PubMed1998

Purification and characterization of a novel cold-regulated protein from an ice-nucleating bacterium, Pseudomonas fluorescens KUIN-1.

The psychrotrophic ice-nucleating bacterium, Pseudomonas fluorescens KUIN-1 respond to a decrease in temperature with the induction of proteins that are classified as cold shock proteins (CSPs). We found the function of a 26-kDa protein of the CSPs in the strain KUIN-1. In strain KUIN-1, a cold shock from 18 to 4 degrees C induced the synthesis of the 26-kDa protein. By analysis with SDS-PAGE, it was then demonstrated that the 26-kDa protein was produced by the cells after treatment at 4 degrees C. The 26-kDa protein was purified to apparent homogeneity by (NH4)2SO4 precipitation and some chromatographies (QA52, phenyl Superose, Superose 12, and Mono Q). The purified 26-kDa protein is composed of 6 subunits of 26.5-kDa with a molecular mass of approximately 159-kDa according to gel filtration and SDS-PAGE. The N-terminal sequence of the 26-kDa protein was Gln-Ala-Ala-Tyr-Tyr-Pro-Ala-His-His-His-Gln- Gln-Val-Gln-Gln-His-Trp-Gly-His-His-. Specifically, 26-kDa protein of the CSPs of strain KUIN-1 was very effective in protecting the cold-labile enzyme, lactate dehydrogenase against denaturation by freezing. The characteristics of 26-kDa protein are analogous to the cold-regulated protein of the plants.

Adaptation, Physiological↗
PubMed1998

Thermal unfolding of the starch binding domain of Aspergillus niger glucoamylase.

A fragment of the starch-binding domain (SBDF) of Aspergillus niger glucoamylase was prepared using recombinant DNA techniques, and its thermal unfolding was investigated by high-sensitivity differential scanning calorimetry (DSC). Thermal unfolding of SBDF was found to be reversible at pH 7 as expected from a DSC study of the whole enzyme molecule [Tanaka A. et al., J. Biochem., 117, 1024-1028 (1995)] but not reversible at acidic region. Numerical analysis of the DSC curves showed that the denaturation was two-state, and some of the SBDF molecules were oligomeric (average degree of oligomerization was 1.2) at pH 7. It was suggested that the denaturation temperature of SBDF was lower than that of the starch-binding domain in the whole enzyme molecule by about 4.5 degrees (decrease in the Gibbs energy change was 5.3 kJ mol-1) indicating a possibility that the starch-binding domain is stabilized by glycosylation of the domain itself, or by the highly glycosylated linker region.

Aspergillus niger↗
PubMed1998

[The cytotoxic effect of topical mitomycin C on the ciliary body in rabbits].

We evaluated the cytotoxic effects of mitomycin C (MMC) in rabbit eyes. A sponge soaked with MMC was placed on the bared sclera after conjunctival incision. We used four concentrations of MMC in distilled water: 0%, 0.04%, 0.1%, and 0.4%. MMC was applied to one eye only, with the fellow eye serving as control. The eyes were studied for intraocular pressure (IOP) and by fluorophotometry at 3, 7, 14, and 28 days of treatment. Eyes treated with 0.04% and 0.4% MMC were studied histologically at 3 and 28 days. All the MMC-treated eyes showed no significant changes regarding IOP (56 eyes) or fluorophotometric features (28 eyes) regarding aqueous humor dynamics and blood-aqueous barrier. Pathologic changes of the ciliary epithelium, including intracellular vacuoles and swelling of mitochondria, were more pronounced in eyes treated with 0.4% MMC than those treated with 0.04%. These changes were more manifest in areas inner to the site of application than in the opposite area. Topical application of 0.04% MMC thus showed no evident toxic effects on the function of the ciliary body and other pathological changes were minor.

Administration, Topical↗
PubMed1998

[The early results of the minimally invasive direct coronary artery bypass (MIDCAB)].

The clinical experiences of 29 consecutive MIDCAB procedures performed at our institution between October, 1996, and October, 1997, were analyzed. Preoperative patient's characteristics were as follows; LAD single vessel disease: 25, double vessel disease: 1, triple vessel disease: 1, RC single vessel disease: 1, LMT lesion: 1, concomitant procedures: 2 (ASO: 1, AAA: 1). LITA harvesting was performed using the video-assisted thoracoscopy in initial 4 patients, and in last 10 patients we used the specially designed retractor THORALIFT (Autosuture Co., Ltd.) for harvesting LITA by direct vision. LAD was stabilized mechanically using the stabilizer when we performed the anastomosis in last 10 patients to enhance the quality of the anastomosis. The patency rate was 96%, but there were two patients (6%) who had the stenosis of the anastomosis site. Coronary artery occlusion time was 13.2 minutes in the mean. We also studied the hemodynamics of blood flow in LITA grafts with the aid of 7.5 MHz transthoracic duplex imaging in these MIDCAB patients and compared with the LITA grafts in conventional CABG performed in same periods. There were no statistical differences between the two groups about the graft flow and velocity. We conclude that MIDCAB would be an alternative procedure that can be performed with low risk and acceptable early results in selected patients.

Aged↗
PubMed1997

Smooth muscle cell phenotype-dependent transcriptional regulation of the alpha1 integrin gene.

The expressional regulation of chicken alpha1 integrin in smooth muscle cells was studied. The alpha1 integrin mRNA was expressed developmentally and was distributed dominantly in vascular and visceral smooth muscles in chick embryos. In a primary culture of smooth muscle cells, alpha1 integrin expression was dramatically down-regulated during serum-induced dedifferentiation. Promoter analyses revealed that the 5'-upstream region (-516 to +281) was sufficient for transcriptional activation in differentiated smooth muscle cells but not in dedifferentiated smooth muscle cells or chick embryo fibroblasts. Like other alpha integrin promoters, the promoter region of the alpha1 integrin gene lacks TATA and CCAAT boxes and contains binding sites for AP1 and AP2. The essential difference from other alpha integrin promoters is the presence of a CArG box-like motif. Deletion and site-directed mutation analyses revealed that the CArG box-like motif was an essential cis-element for transcriptional activation in differentiated smooth muscle cells, whereas the binding sites for AP1 and AP2 were not. Using specific antibodies, a nuclear protein factor specifically bound to the CArG box-like motif was identified as serum response factor. These results indicate that alpha1 integrin expression in smooth muscle cells is regulated transcriptionally in a phenotype-dependent manner and that serum response factor binding plays a crucial role in this regulation.

Animals↗
PubMed1997

Detection of canine pemphigus foliaceus autoantigen by immunoblotting.

The antigens targeted by autoantibodies in sera from canine patients with pemphigus foliaceus (PF) were detected by indirect immunofluorescence and Western immunoblotting. The extracted proteins from canine keratinocytes cultured in high-calcium condition for 48 h after confluency and from bovine nose epidermis were used as antigens in Western blotting. Canine keratinocytes cultured in high-calcium condition showed fluorescent deposits in intercellular spaces by incubation with sera from both canine and human pemphigus patients. By Western blotting, eight out of 16 canine PF sera recognised 160 kDa protein. 85 kDa and 120 kDa proteins were also recognised by four to five canine PF sera, respectively. The 160 kDa band, recognised by eight canine PF sera, had an identical mobility to the protein identified by a human PF serum. These results suggested that the autoantibodies in sera from canine PF recognised the 160 kDa desmosomal proteins, which may correspond to the desmoglein 1.

Animals↗
PubMed1997

GABAergic neurotransmission in rat taste buds: immunocytochemical study for GABA and GABA transporter subtypes.

Gamma-aminobutyric acid (GABA) is known to be a candidate for the neurotransmitter involved in the sense of taste. We hereby studied GABA and its termination system, GABA transporters, in rat taste buds by immunocytochemical approaches. Immunoblot analysis of three GABA transporter subtypes (GAT1, GAT2 and GAT3) revealed that the immunoreactive bands of GAT2 and GAT3, but not GAT1, were detected in the tongue. GAT3-immunoreactive band was recognized only in the circumvallate papilla containing a large number of taste buds while GAT2-immunoreactive bands were seen in all areas of the tongue. GAT2 immunoreactivity appeared to be specifically in the nerve fibers beneath the lingual epithelium. Both GAT3 and GABA immunoreactivities were detected only in taste buds. A few GAT3-immunoreactive cells were found in a cross-section of each taste bud but most GAT3-immunoreactive cells were localized in the margin of the taste bud. GAT3 was predominantly concentrated in the distal portion of the GAT3-immunoreactive cells. In contrast, GABA-immunoreactive cells were seen more frequently within each taste bud and the immunoreactivity was distributed throughout the perikarya of the cells. These results suggest that the GABA-uptake system is present in the taste buds and the GABAergic neurotransmission involved in the sensation of taste is terminated by the uptake of GABA into certain taste cells via GAT3.

Animals↗
PubMed1997

Ganglioside composition of the human cranial nerves, with special reference to pathophysiology of Miller Fisher syndrome.

Total ganglioside fractions from the human cranial nerves purified on a Phenyl Sepharose column, were given mild alkaline treatment, after which their composition and amounts of lipid-bound sialic acid were determined by HPTLC-densitometry with resorcinol as the coloring reagent. The total amounts of lipid-bound sialic acid were 156.5 ng/mg of wet tissue in the Ist cranial nerve (olfactory tract) and 131.9 ng/mg in the IInd nerve, greater than the amounts in the other nerves (99.1-120.0 ng/mg). The Ist, IInd, and VIIIth nerves had GM4, but not LM1. It may reflect their histological feature of the central nervous system. The IIIrd, IVth, and VIth nerves, as well as the IInd, had significantly higher percentages of GQ1b (11.6-13.2%) than the other nerves (5.2-8.4%). The high proportion of GQ1b specific to these three cranial nerves involved in the ocular movement lends support to the role of serum anti-GQ1b antibody in the pathogenetic mechanisms of ophthalmoplegia in Miller Fisher syndrome and Guillain-Barré syndrome.

Aged↗
PubMed1997

[Evaluation of a latex agglutination method for detecting and characterizing verotoxin (VT) produced by Escherichia coli].

The detection of VT produced by Escherichia coli is very important for the identification of verotoxin-producing Escherichia coli (VTEC). The latex agglutination reagents (Denka Seiken Co. Ltd, Tokyo) which was developed to detect VT was compared with the vero cell bioassay or polymerase chain reaction method. A total 147 VT-positive strains (109 serotype O157:H 7/- and 38 non-O157 serotype) and 31 VT-negative strains which were isolated from human were investigated. In addition, a total of 79 VT-positive strains (14 serotype O157:H7/- and 65 non-O157 serotype) and 79 VT-negative strains which were isolated from animals were also examined. The latex agglutination assay for the human isolates showed the 100% sensitivity, specificity and agreement. The assay for the animal isolates showed 94.9% sensitivity, 100% specificity and 97.5% agreement. Although 4 of 8 strains isolated from swine which produce VT2 variant toxin (VT2e) failed in detecting verotoxin by latex agglutination assay, VT2e was not related to human infections. We conclude that this latex agglutination reagent is highly sensitive and specific for detecting and characterizing VT of E. coli. The method is reliable, easy to perform at any laboratories.

Animals↗
PubMed1997

[Biochemical and molecular characterization of Salmonella serovar enteritidis phage type 4 isolated from food poisoning outbreaks in Tokyo].

Since 1989, outbreaks of Salmonella ser. Enteritidis (S. Enteritidis) food poisoning have dramatically increased in Tokyo, and a total of 31 outbreaks has been reported in 1989. Twenty-one of these 31 outbreaks were caused by S. Enteritidis PT34, but 8 outbreaks were caused by S. Enteritidis PT4. After 1990 instead of SE PT34, food poisoning due to PT4, which was a very common phage type in the UK, has increased in Tokyo. Between 1989 and 1995, there were 144 food poisoning outbreaks caused by S. Enteritidis, and 64 of these outbreaks were by due to S. Enteritidis PT4, which was one of the main phage types in Tokyo. To characterize these strains of phage type (PT) 4,293 isolates from patients, and vehicle foods, eggs and environment in Tokyo were examined for plasmid DNA profiles, acid productivity from glycols (propylene and ethylene) and antimicrobial resistance patterns. Plasmid DNA was extracted by Kado's method, and analyzed by agarose gel electrophoresis. The acid productivity from propylene glycol or ethylene glycol were tested using Barsicow medium with 1% propylene glycol or ethylene glycol. Antimicrobial susceptibility to AM, CP, TC, SM, KM, NA, ST, FOM and NFLX was tested by the K-B disc method. The strains of PT4 were further subdivided into 9 types by those epidemiologic marker analysis. The prevalent pattern of PT4 strains was type A plasmid profile carrying only one plasmid (60 kb) and there were 2 kinds of antibiograms. One was SM resistant, while the other was susceptible. A total of 56 (87.5%) of 64 outbreaks was found to have been caused by these types of S. Enteritidis. Several kinds of egg-related foods were suspected as the vehicles of transmission among 24 outbreaks. Especially, in 5 outbreaks, S. Enteritidis strains were isolated both from patients and suspected food which were cooked with egg. This strongly suggests that these foods may be the potential source of infection in S. Enteritidis PT4 outbreaks.

Anti-Bacterial Agents↗
PubMed1997

Purification and properties of an aminopeptidase from a protamine-degrading marine bacterium.

A protamine-degrading marine bacterium was isolated from marine soil and identified as Aeromonas salmonicida subsp. based on its taxonomical characteristics. An alanine-specific aminopeptidase, called aminopeptidase K, from an extract of the strain was purified and characterized. The aminopeptidase K was purified about 80-fold by fractionation with ammonium sulfate and column chromatography on QA-52 cellulose, Phenyl Superose and Superose 12. The purified enzyme is composed of 6 subunits of 86 kDa with a molecular mass of 520 kDa according to gel filtration and SDS-PAGE. The N-terminal sequence of the enzyme was H.Gly-Gln-Gln-Pro-Gln-Ile-Lys-Try-Tyr-His-Asp-Tyr-Asp-Ala-Pro-Asp-Tyr-Ty r- Ile-Thr-. It is inhibited by monoiodoacetate, N-ethylmaleimide, and puromycin. The Michaelis constant (K(m)) and the maximal rate of hydrolysis (Vmax) were, respectively, 0.28 mM and 49.4 mumol/min/mg for the L-Ala-beta-naphthylamide substrate. The optimum pH and optimum temperature were 6.5 and 45 degrees C, respectively. The purified enzyme was highly specific to L-Ala-beta-naphthylamide.

Aeromonas↗
PubMed1997

[Effects of topical corticosteroids on subepithelial haze after excimer laser corneal surgery--objective and quantitative method for evaluating haze].

To examine the effectiveness of topical corticosteroids in decreasing subepithelial haze induced by excimer laser keratectomy, we performed excimer laser keratectomy on 24 eyes of 12 albino rabbits using a scanning excimer laser system (EC-5000, NIDEK, Japan). Topical dexamethasone 0.1% was applied topically to 8 corneas after surgery (steroid group), but not to the others (control group). Slit-lamp biomicroscopic examination and objective measurement of scattered light from subepithelial haze were performed before and 2, 4, 8 and 12 weeks after surgery, the rabbits were killed after 2 or 12 weeks and the eyes were examined histologically. In both groups, densitometric values of scattered light intensity increased up to 4 weeks after surgery, and then decreased gradually. However, the values of the steroid group were larger than those of the control group at all stages, and the values of the steroid group at 12 weeks after surgery were similar to preoperative values. There was statistically significant difference in scattered light intensity between the two groups (p < 0.005). Two weeks after surgery, the corneas of the control group showed epithelial hyperplasia and a remarkable increase in activated keratocytes and subepithelial fibrous tissues. However, in the steroid group these light microscopic findings could not be observed. At 12 weeks after surgery, the corneas of the control group retained a small amount of activated keratocytes and fibrous tissues, and those of the steroid group were normal. This study suggests that a short course of topical corticosteroids may be very effective in decreasing subepithelial haze after excimer laser corneal surgery.

Administration, Topical↗
PubMed1997

[Functions of the transforming growth factor-beta superfamily in eyes].

One human body is composed of 6 x 10(13) cells, and eyes are also composed of many cells of different functions. The cellular functions and intercellular interaction are regulated by many regulators including cytokines and growth factors to maintain the homeostasis. The transforming growth factor-beta (TGF-beta) superfamily, a large family of multifunctional factors, regulates various cellular functions, including cellular proliferation, migration, differentiation, apoptosis and extracellular matrix production. The TGF-beta superfamily contains about 30 multifunctional factors, and is divided into several families according to the sequence homology. The TGF-beta family, the activin family, and bone morphogenic proteins belong to the TGF-beta superfamily. TGF-beta superfamily members transduce signals through type I and type II serine/threonine type transmembrane receptors. The signals are transduced from receptors through nuclei by Smad family members, which are phosphorylated by the activated type I receptors and translocate from cytoplasm into nuclei. TGF-beta family members and the TGF-beta superfamily receptor family are expressed in ocular tissues including the cornea, ciliary epithelium, lens epithelium, retina, and blood vessels. This observation suggests the importance of the TGF-beta superfamily in eyes. Smad family members (Smad 1, Smad 2, Smad 3 and Smad 4) are expressed in the cultured retinal pigmant epithelial cell line (D407), in which TGF-beta and activin A stimulate the translocation of Smad 2, but not Smad 1 into nuclei, whereas bone morphogenetic protein (BMP) stimulates that of Smad 1, but not Smad 2. TGF-beta superfamily members play important roles in the pathogenesis of retinal neovascularization and in the wound healing process of corneal tissue. TGF-beta inhibits the endothelial functions, but, stimulates angiogenesis in vivo. TGF-beta is involved in the formation of abnormal connective tissue in corneal wound healing. In these processes, many cytokines and growth factors are involved, interacting with each other and forming networks. It is mandatory to clarify the networks to investigate molecular pathogenesis and new therapeutic agents.

Diabetic Retinopathy↗
PubMed1996

P21waf-1/cip-1/sdi-1 is expressed at G1 phase in primary culture of hepatocytes from old rats, presumably preventing the cells from entering the S phase of the cell cycle.

To elucidate whether p21waf-1/cip-1/sdi-1 expression is associated with loss of growth potential of hepatocytes of old rats, we determined p21waf-1/cip-1/sdi-1 expression of hepatocytes from old (30 months) rats during the cell cycle in primary culture. A high level of expression of p21waf-1/cip-1/sdi-1 was detected at the G1 phase in old-rat hepatocytes, but after the S phase in young-rat hepatocytes. Consistently, the incidence of the cells positive for p21waf-1/cip-1/sdi-1 in nuclei before entering the S phase was significantly higher in old-rat hepatocytes than in young-rat hepatocytes. These results account for the loss of growth potential of old-rat hepatocytes in vitro and the marked retardation of regeneration of liver in old rats in vivo.

Animals↗
PubMed1996

NF-kappa B is induced in the nuclei of cultured rat aortic smooth muscle cells by stimulation of various growth factors.

We investigated whether induction of transcription factor NF-kappa B is involved in the proliferation of cultured rat aortic smooth muscle cell using electrophoretic mobility shift assay and immunocytochemistry. NF-kappa B was induced in the nucleus in a dose-dependent manner when the smooth muscle cells were stimulated by various growth factors such as PDGF-BB, bFGF, EGF and IGF-1, but not growth inhibitors such as TGF-beta and IFN-gamma. Among growth factors, PDGF-BB and bFGF, more potent growth stimulators, induced higher kappa B binding activity than EGF or IGF-1. These evidences were also supported by the results obtained with immunocytochemistry. Immunocytochemistry also showed that the induced NF-kappa B contained p50 and p65. These results suggest that NF-kappa B induction may be involved in the proliferation of vascular smooth muscle cell.

Animals↗