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Biomedical subjects

N Ogata

Publications and source records attributed to N Ogata.

At least 145 records · Page 8Linked to original sources
PubMed1994

Heterogeneous eosinophils of allergic rhinitis in chemotactic response.

Chemotactic responses of eosinophils from patients with allergic rhinitis to 5 STO-2-derived eosinophil chemotactic factors (ECF), IL-3, IL-5 and GM-CSF were examined. The patients were divided into two groups: patients with perennial allergic rhinitis sensitive to Dermatophagoides farinae and those with seasonal allergic rhinitis sensitive to Japanese cedar pollen. There was no essential difference between chemotactic response of eosinophils from the former to STO-2-derived ECF and that from healthy individuals. However, eosinophils from patients with seasonal allergic rhinitis failed to respond to one of the STO-2-derived ECFs, ECF-P19. Before and after nasal antigen provocation, no change occurred in the chemotactic profiles. Furthermore, we found that eosinophils from both types of patients with allergic rhinitis responded not only to IL-3 and GM-CSF but also to IL-5 unlike those of healthy individuals.

Cell Line↗
PubMed1994

Postadsorptive behavior of plasma proteins on poly(propylene oxide)-segmented nylon-610 surfaces and its implication in preventing contact-induced activation of platelets on these surfaces.

The influence of adsorbed plasma proteins on preventing contact-induced activation of platelets on poly(propylene oxide) (PPO)-segmented nylon-610 surfaces was investigated by monitoring changes in cytoplasmic free Ca2+ concentrations in platelets and adsorption/desorption of albumin and fibrinogen on these copolymer surfaces. Direct measurement of cytoplasmic free Ca2+ concentration in platelets in contact with copolymer surfaces was achieved by monitoring spectral changes of a fluorescent indicator dye, Fura 2. These copolymers were characterized by a surface microstructure composed of coexisting crystalline and amorphous phases. An increase in cytoplasmic free Ca2+ concentration in platelets interacting with polymer surfaces was observed, and this increase was found to be strongly reduced both by the adsorption of plasma proteins into the polymer surface and by modifying the surface microstructure of the polymer itself. Transient changes in cytoplasmic free Ca2+ concentration were observed in platelets in contact with the surface of copolymer 61P3-25, which exhibited excellent nonthrombogenicity in our previous studies, depending on the residence time of plasma and plasma concentration. Additionally, adsorption/desorption of albumin and fibrinogen on copolymer surfaces was estimated using 125I-labeled proteins. Exchange of the adsorbed albumin with fibrinogen and minimum fibrinogen adsorption were observed particularly on the 61P3-25 surface. Exchange of adsorbed fibrinogen with plasma proteins and/or increased fibrinogen adsorption were also observed on all other polymer surfaces examined. Finally, we conclude that controlled formation of a defined protein adsorption layer on the 61P3-25 surface via the transient exchange of adsorbed albumin with fibrinogen from plasma, can be a dominant factor in preventing platelet adhesion and activation on this surface.

Adsorption↗
PubMed1994

[Immunohistological study in Bruch's membrane of senescence accelerated mouse].

Age-related macular degeneration is one of the major causes of severe visual loss is elderly individuals. However, relatively little is known about its etiology. The disease may be associated with senescence. Ultrastructural and immunohistochemical studies on SAM (senescence accelerated mouse) eyes were carried out to learn details of aging changes in the retinal pigment epithelium (RPE) and Bruch's membrane. SAM P 1 mice aged 2, 10, 14 months were examined in this study. The eyes were analysed for type IV collagen and heparan sulfate proteoglycan (HSPG) by the avidin-biotin-peroxidase complexes (ABC) method and post-embeddig immunolocalization with colloidal gold. With the ABC method, the basement membranes of both the RPE and the choriocapillaris showed markedly positive staining when treated with anti-type IV collagen antibody and moderately positive staining when treated with anti-HSPG antibody. In ultrastructural immunolocalization, both basement membranes showed fairly heavy labeling in response to the antibodies to type IV collagen, and moderate labeling in response to the antibodies to HSPG. With aging, the thickness of the basement membrane of the choriocapillaris and gold particle labeling by the antibodies to type IV collagen increased. The gold particle labeling by the antibodies to HSPG increased slightly, but was distributed sparsely. These results showed the advancing process of senescence changes in Bruch's membrane.

Aging↗
PubMed1994

[Proteoglycan in Bruch's membrane of senescence accelerated mouse: localization and age-related changes].

We demonstrated the distribution of sulfated proteoglycans in Bruch's membrane of Senescence Accelerated Mouse histochemically and ultrastructurally using cuprolinic blue in conjunction with specific enzyme treatments and nitrous acid digestion. Two kinds of proteoglycan filaments were observed in the inner and outer collagenous layers, i.e., small collagen fibril-associated filaments (11 nm in average length), and large filaments (32 nm in average length). Intermediate size filaments (25 nm in average length) were seen in the basement membranes of the retinal pigment epithelium and choriocapillaris. Chondroitinase AC treatment eliminated the staining of filaments in the collagenous layers (chondroitin sulfate). Chondroitinase ABC treatment also eliminated the staining of filaments in the collagenous layers (chondroitin sulfate and dermatan sulfate). Nitrous acid eliminated the staining of filaments in both basement membranes (heparan sulfate). Proteoglycans containing chondroitin sulfate and dermatan sulfate were associated uniquely with collagen fibrils. Heparan sulfate proteoglycans were associated with the basement membranes of the pigment epithelium and choriocapillaris. With aging, the thickness of the basement membrane of the choriocapillaris and the staining of the filaments in the basement membranes of the pigment epithelium and choriocapillaris (heparan sulfate proteoglycans) increased. Collagen fibers became disarranged and the staining of both filaments in the collagenous layers decreased. The results of the staining characteristics probably reflect the aging of Bruch's membrane.

Aging↗
PubMed1994

Alteration of in vivo cytokine gene expression in mice infected with a molecular clone of the defective MAIDS virus.

The discovery of T helper type 1 (Th1) and T helper type 2 (Th2) phenotypes within the CD4+ T-lymphocyte population has allowed for further elucidation of the roles the T cells play in regulation of humoral and cellular immunity. It is suggested that differential activation of the CD4+ subsets, particularly up-regulation of the Th2 cell and down-regulation of the Th1 cell, may be associated with diseases as diverse as AIDS and asthma. We report herein that by using the polymerase chain reaction to analyze the kinetics of in vivo cytokine- and virus-specific gene expression, we can show that mice infected with the molecularly cloned MAIDS defective virus 1/27/A BM5 exhibit an alteration in cytokine gene expression that closely parallels an increase in spleen cell numbers, an increase in IgM production, a decrease in the stimulation index, and an increase in defective-virus gene expression in these mice. As has been suggested to be true for human AIDS, the observed alteration of cytokine gene expression suggests that a pattern of expression similar to that produced by Th2 cells may also have a role in the development of MAIDS.

Animals↗
PubMed1993

[Clinical experiences in using ITC silastic detachable balloons--report on 30 cases with various neurovascular diseases].

As defective balloons often lead to disasters, reliable detachable balloons have long been eagerly awaited. We had the opportunity of using ITC detachable balloons on 30 cases with various neurovascular diseases. No defective balloon was found during in vitro testing done immediately prior to their placement in the patient's vascular system. Moreover, there was no premature detachment during catheter manipulation or early deflation within several weeks after detachment. Both immediate and long term follow up showed balloon embolization would be the first choice for various direct arteriovenous fistulae. Also, anatomically inaccessible aneurysms with small necks, less than 1 cc in volume, could be successfully treated by detachable balloons. However, detachable balloons are not ideal embolic material for large and giant aneurysms. In conclusion, when used by properly trained personnel, ITC silastic detachable balloons are a safe, easy to use and reliable option.

Adolescent↗
PubMed1993

Markedly prolonged incubation period of hepatitis B in a chimpanzee passively immunized with a human monoclonal antibody to the a determinant of hepatitis B surface antigen.

The protective efficacy of a human monoclonal antibody directed against the a determinant of hepatitis B virus (HBV) surface antigen was studied in a chimpanzee. A single high dose of 5 mg/kg (body weight) of monoclonal antibody SDZ OST 577 was intravenously administered to a chimpanzee, followed by intravenous challenge with 10(3.5) chimpanzee infectious doses of a wild-type HBV, the MS-2 strain (ayw subtype). The passively acquired antibody to HBV surface antigen could be detected for 40 weeks. Serum HBV DNA tested by a "nested" polymerase chain reaction assay was negative through the 36th week after virus challenge but became positive by the 38th week. The chimpanzee subsequently developed acute hepatitis B approximately 1 year after challenge. The nucleotide sequence of the a determinant of the surface gene of the replicated virus was identical with that of the inoculated wild-type virus. Thus, a human monoclonal antibody directed against the a determinant of HBV surface antigen delayed but did not prevent experimental infection of HBV and hepatitis in the chimpanzee. Our results indicate an incomplete ability of this antibody to protect against HBV infection in vivo after a single infusion.

Amino Acid Sequence↗
PubMed1993

Differential inhibition of transient and long-lasting calcium channel currents by benzodiazepines in neuroblastoma cells.

The effects of diazepam, nitrazepam, clonazepam, and Ro5-4864 on transient (type I) and long-lasting (type II) calcium channels associated with low-affinity benzodiazepine receptors were investigated using the whole-cell patch-clamp technique. Clonazepam (100 microM), a specific agonist for the central-type benzodiazepine receptor, reduced transient currents through the type I calcium channel by 40% without affecting long-lasting currents through the type II calcium channel. Diazepam and nitrazepam (100 microM), non-specific agonists for both the central- and peripheral-type benzodiazepine receptors, reduced both transient and long-lasting currents equally by 25-30%. A similar non-selective inhibition was observed by Ro5-4864 (1-10 microM), a specific agonist for the peripheral-type benzodiazepine receptor. It is concluded that the two calcium channel types are regulated differentially by two different kinds of benzodiazepines; central-type for type I channel and peripheral-type for both type I and type II channels.

Animals↗
PubMed1993

The complete nucleotide sequence of a pre-core mutant of hepatitis B virus implicated in fulminant hepatitis and its biological characterization in chimpanzees.

Hepatitis B virus (HBV) with an in-frame stop codon within the pre-core region of the virus genome caused fulminant hepatitis in two individuals. Serum from a chronically infected patient who was the source of the virus was inoculated into three chimpanzees at dilutions of 10(-1), 10(-3), and 10(-7). All three chimpanzees developed acute hepatitis B with relatively high peak values of liver enzymes in their serum. The complete nucleotide sequence of virus DNA recovered from the chimpanzee serum by enzymatic amplification was identical with that from the human serum. By comparing the sequence of this strain (HT) with that of 32 published HBV genomes, changes in nucleotides and predicted amino acids that were rarely or never found in other HBV isolates were identified. Thirteen such nucleotides were found within the cis-acting regulatory elements, of which 6 were within the enhancer II-core promoter region. Twenty-four rare or unique changes in amino acids were found in open reading frames, of which 15 occurred in the region that spanned the 3' half of the X gene, through the pre-core/core gene, to the 5' end of the polymerase gene. Thus, an HBV pre-core stop mutant implicated in fulminant hepatitis is highly infectious, induces severe hepatitis in chimpanzees, and possesses significant genetic variation from reported HBV isolates.

Animals↗
PubMed1993

Beta-D-glucan concentrations detected by Toxicolor and Endospecy tests in the urine of patients with urinary fungal infections.

Beta-D-glucan is an essential component of the cell wall of fungi. We measured its concentration in the urine of patients with funguria using the chromogenic endotoxin assay kits, Toxicolor and Endospecy. These assay systems use the same Limulus coagulation enzymes. Since the Endospecy test detects endotoxin but not factor G, which is activated by beta-D-glucan, the beta-D-glucan concentration can be calculated by subtracting the Endospecy value from the Toxicolor value. Concentrations of beta-D-glucan were found to be significantly higher in urine samples from patients with funguria (> or = 10(3) colony-forming units/ml) than in non-infected samples.

Bacterial Infections↗
PubMed1993

Direct inactivation of human polymorphonuclear leukocyte by hyperosmotic urea comparable to the renal medulla.

Hyperosmolarity in the renal medulla inhibits host defenses against bacterial pyelonephritis. Urea and NaCl contribute most to high osmolarity in the renal medulla. We therefore examined the inhibitory mechanism of urea on superoxide generation by human polymorphonuclear leukocytes. Superoxide production was inhibited by high concentration of urea. This inhibition was found to be direct and immediate. In addition, direct inactivation of NADPH oxidase, the key enzyme complex of superoxide generation, was shown by an NADPH oxidase activity assay using cell lysates of polymorphonuclear leukocytes stimulated by phorbol myristate acetate. The inhibitory effect of urea on NADPH oxidase was reversed by washing urea out of the assay system of cell lysates. Kinetic analysis of the inhibition of NADPH oxidase activity by urea showed decreased Vmax and Km, suggesting uncompetitive inhibition. These findings suggested that urea inactivated polymorphonuclear leukocyte superoxide production through a direct and uncompetitive inhibition of NADPH oxidase.

Dose-Response Relationship, Drug↗
PubMed1993

Pulse methylprednisolone therapy in the treatment of Wegener's granulomatosis.

Five patients with Wegener's granulomatosis were treated with high-dose intravenous methylprednisolone (MTP) pulse therapy. Three out of five patients received MTP pulse therapy as the initial treatment and remission was achieved. Renal biopsy after the treatment confirmed the improvement of kidney involvement in 2 cases. Although the other two patients received MTP pulse therapy when a relapse occurred, the therapy could not suppress the progression of the disease. These observations suggest that MTP pulse therapy when given early may make it possible to suppress the progression of kidney involvement and improve the prognosis of the disease. Furthermore, it may also decrease the total doses of oral steroids and cyclophosphamide because of a strong anti-inflammatory and immunosuppressive action and consequently diminish the side effects. In conclusion MTP pulse therapy as the initial treatment may be beneficial in treating patients with Wegener's granulomatosis.

Adult↗
PubMed1993

Alterations of a 200 kDa neurofilament in the rat hippocampus after forebrain ischemia.

Alteration in the concentration of a 200 kDa neurofilament (NF200) in the rat hippocampus after forebrain ischemia and its relationship to hippocampal neuronal death were studied with an anti-200 kDa neurofilament antibody, using immunohistochemical and immunoblotting techniques. In rats subjected to 8 min of transient forebrain ischemia, hematoxylin-eosin staining showed survival of most of the neurons in the hippocampal CA1 region at 1 day and loss of more than 75% of the neurons at 7 days after ischemia. Immunoblotting showed that the concentration of NF200 in the hippocampal homogenate tended to decrease after ischemia, to 69% of that of control at 1 day and to 60% of the control value at 7 days after 8 min of forebrain ischemia. Following 5 min of ischemia as well, the decrease in the concentration of neurofilaments in the hippocampal region preceded histological confirmation of neuronal cell death. These results suggest that degradation of neurofilament triplet proteins occurred even after ischemia of minimal duration and preceded neuronal death. Degradation of cytoskeletal proteins may play an important role in the mechanism of delayed neuronal death after cerebral ischemia.

Animals↗
PubMed1993

Differential inhibition of a transient K+ current by chlorpromazine and 4-aminopyridine in neurones of the rat dorsal root ganglia.

1. K+ currents were recorded from neurones of the newborn rat cultured dorsal root ganglia, by a whole cell variation of the patch-clamp technique. 2. Chlorpromazine (CPZ), a neuroleptic, reversibly reduced the amplitude of the transient K+ current (referred to as 'IT' hereafter) with a dissociation constant (Kd) of 4.5 microM. The inhibition of the delayed rectifier K+ current (IDR) was much less potent (Kd, 120 microM). CPZ (100 microM) had no effect on the inward rectifier K+ current. 3. The blocking action of CPZ on IT was about seven times more potent than that of 4-aminopyridine (4-AP) which had a Kd of 31 microM. The inhibition of IT followed one-to-one binding stoichiometry with both drugs. 4. The decay time course of IT was not affected by CPZ, whereas 4-AP markedly accelerated the decay phase of IT. 5. The steady-state inactivation curve of IT was shifted in the negative direction (about 5 mV) by CPZ, whereas the curve was shifted in the positive direction (about 13 mV) by 4-AP. 6. The recovery from inactivation as measured by a conventional double pulse protocol was described by two exponential components in the control solution. CPZ markedly reduced the first component and slowed down the recovery from inactivation. In contrast, in the presence of 4-AP, the peak amplitude of IT was rather increased by a preceding IT possibly through voltage-dependent unbinding of 4-AP molecules. 7. These results indicate that CPZ has a preferential blocking action on IT and the mechanism underlying this block is markedly different from the mechanism underlying the blocking action of 4-AP.

4-Aminopyridine↗
PubMed1993

Demonstration of antidiarrheal and antimotility effects of wood creosote.

Wood creosote administered to rats prevented castor-oil-induced diarrhea with an ED50 of 53 mg/kg p.o. This antidiarrheal effect was apparently produced by acceleration of net fluid absorption from the intestine, as shown by a 52% decrease (p < 0.001) of residual fluid volume in an intestinal loop, and partly by suppression of intestinal motility. Wood creosote also inhibited spontaneous longitudinal contractions of isolated ileal segments in rats (IC50 = 28 mg/l) and guinea pigs (IC50 = 17 mg/l). Contractions of the guinea pig ileum induced by electrical stimulation, bradykinin and acetylcholine were also inhibited dose-dependently. We conclude that wood creosote has an antidiarrheal activity and that this effect is exerted by inhibition of intestinal motility and by augmentation of net fluid absorption from the intestine.

Acetylcholine↗
PubMed1993

Suppression of intestinal smooth muscle contraction by 4-ethylguaiacol, a constituent of wood creosote.

Wood creosote, a mixture of phenolic compounds, suppresses in vitro contractions of rat intestine. To identify a compound in wood creosote able to inhibit intestinal motility, we screened its constituent phenolic compounds and found 4-ethylguaiacol (4-EG) as an active compound. It suppressed the spontaneous phasic (IC50 = 513 +/- 48 mumol/l) as well as spasmogenic-agent-induced tonic longitudinal contractions of isolated rat ileum in a reversible and concentration-dependent manner. KCl-depolarization-induced tonic contraction, which was susceptible to a calcium channel blocking agent, was also suppressed by 4-EG with an IC50 of 433 +/- 41 mumol/l. Furthermore, calcium-ionophore-induced contraction, which was affected by an influx of extracellular calcium ion that bypassed calcium channels, was suppressed by 4-EG with an IC50 of 97 +/- 18 mumol/l. These results support the concept that the effect of wood creosote to suppress intestinal motility is attributable, partially or entirely, to its component 4-EG and that this effect of 4-EG on the intestinal muscle is produced at some stage(s) of the muscle contraction process after influx of extracellular calcium into the cytosol of smooth muscle.

Animals↗
PubMed1993

Enhancement of superoxide production of polymorphonuclear neutrophils by ofloxacin and the effects of the inhibitors of protein kinase C.

Polymorphonuclear neutrophils (PMN) represent an important defense mechanism against bacterial infection. Superoxide is one of the most important factors released by PMN following various stimulations including bacteria. Augmentation of chemiluminescence response of PMN stimulated by phorbol myristate acetate was observed following the addition of 25-200 micrograms/ml of ofloxacin, a new quinolone antimicrobial agent. In addition, the effects of two inhibitors of protein kinase C, staurosporine and H-7, were examined. The augmented superoxide production was inhibited by 1 or 2 microM of staurosporine or 50 or 100 microM of H-7. These results suggest that ofloxacin augments superoxide production of PMN and that this augmentation is probably due to the enhancement of leukocyte protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗