Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 379 records · Page 21Linked to original sources

PubMed1998

Cigarette smoking decreases interleukin-8 secretion by human alveolar macrophages.

Cigarette smoking can impair pulmonary immune function, and hence influences the development of lung diseases. Interleukin-8 (IL-8) is a proinflammatory peptide and a potent chemotactic factor for neutrophils, and is produced by both immune and non-immune cells including monocytes and alveolar macrophages (AM). We investigated the effect of cigarette smoking on the secretion of IL-8 by human AM. The IL-8 concentration in bronchoalveolar lavage fluid (BALF) was much higher in smokers than in non-smokers (18.4 +/- 3.9 vs 4.1 +/- 1.0 pg ml-1; P < 0.005). However, spontaneous IL-8 secretion by cultured AM was lower in smokers than in non-smokers (46.8 +/- 12.7 vs 124.1 +/- 24.0 ng ml-1; P < 0.01). When stimulated with lipopolysaccharide (LPS), AM from smokers secreted significantly less IL-8 than those from non-smokers at all tested concentrations of LPS. In contrast, the amount of IL-8 secreted by peripheral blood monocytes with or without LPS stimulation was comparable in smokers and non-smokers. These observations indicate that smoking decreases IL-8 secretion by AM, which may modify or decrease the inflammatory response in the lung.

Aged↗

PubMed1998

Regulation of RANTES and IL-8 production in normal human dermal fibroblasts by active vitamin D3 (tacalcitol).

1. The production of chemokines, RANTES and IL-8 in cultured human dermal fibroblasts and the effects of tacalcitol (1alpha,24(R)-dihydroxyvitamin D3) were studied using an enzyme-linked immunosorbent assay. 2. In the unstimulated condition, RANTES and IL-8 were at a trace level in the culture supernatant. On stimulation with TNF-alpha alone for 24 h, RANTES and IL-8 production were induced. Tacalcitol suppressed RANTES and IL-8 production dose-dependently at concentrations between 10(-12) M and 10(-7) M. 3. When the cells were treated with TNF-alpha and IFN-gamma in combination, RANTES production was enhanced, but IL-8 production was not changed, compared to TNF-alpha-treated cells. Tacalcitol decreased IL-8 production dose-dependently as observed in the TNF-alpha-treated cells. On the other hand, RANTES production was enhanced by 10(-11) M and 10(-10) M of tacalcitol, and dose-dependently suppressed by tacalcitol concentrations higher than 10(-9) M. 4. Active vitamin D3 compounds, betamethasone valerate and cyclosporin A were compared with respect to their effects on chemokine production. Three active vitamin D3 compounds, tacalcitol, 1alpha,25-dihydroxyvitamin D3 and MC903 (calcipotriol), inhibited the production of RANTES and IL-8, with very similar potencies. Betamethasone valerate also inhibited these chemokine productions, but with greater potency than active vitamin D3 compounds. Cyclosporin A significantly stimulated RANTES production at 10(-6) M and IL-8 production at 10(-7) M and 10(-6) M. 5. The results of this study suggest that active vitamin D3 compounds exert some beneficial effects in the treatment of inflammatory skin diseases via regulation of the production of chemokines by dermal fibroblasts.

Betamethasone↗

PubMed1998

RANTES expression in psoriatic skin, and regulation of RANTES and IL-8 production in cultured epidermal keratinocytes by active vitamin D3 (tacalcitol).

The chemokine RANTES is a chemoattractant for eosinophils, T lymphocytes of memory phenotype and monocytes, suggesting that it plays an important part in chronic inflammatory and allergic diseases. In various types of cells, RANTES production is markedly induced by tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma in combination. Psoriasis vulgaris is a chronic cutaneous inflammatory disease. Cytokines and chemokines produced by T cells and epidermal keratinocytes, such as interleukin (IL) 8, are involved in the pathogenesis of psoriasis. T-cell clones obtained from psoriatic skin have been shown to produce the Th1 cytokine IFN-gamma. In addition, abnormal expression of proinflammatory cytokines including TNF-alpha has been observed in psoriatic lesions. These reports led us to hypothesis that psoriatic skin could provide epidermal keratinocytes with TNF-alpha and IFN-gamma, so that keratinocytes could produce RANTES. In this study, we addressed the question as to whether RANTES was involved in psoriasis vulgaris. Immunohistochemistry of skin biopsies showed RANTES was present in the intercellular spaces between epidermal keratinocytes, in the fully developed lesions from the middle to the edge of psoriatic plaques, but not in the perilesional uninvolved and healthy control skin. Further, we confirmed the production of RANTES, together with IL-8, by cultured normal human epidermal keratinocytes, using an enzyme-linked immunosorbent assay. Stimulation with TNF-alpha and IFN-gamma in combination synergistically increased the RANTES production in this system. These results clearly demonstrate the expression of RANTES in psoriatic lesions and suggest the involvement of this chemokine in the outcome of cutaneous inflammatory diseases. Tacalcitol (1 alpha,24(R)-dihydroxyvitamin D3), an active vitamin D3 analogue, inhibited RANTES and IL-8 production in cultured normal epidermal keratinocytes. This result indicates that active vitamin D3 is effective in the regulation of chemokine production by epidermal keratinocytes, which may partly account for its action as an antipsoriatic drug.

Cell Culture Techniques↗

PubMed1998

Rad52 forms ring structures and co-operates with RPA in single-strand DNA annealing.

BACKGROUND: The RAD52 epistasis group in Saccharomyces cerevisiae is involved in various types of homologous recombination including recombinational double-strand break (DSB) repair and meiotic recombination. A RecA homologue, Rad51, plays a pivotal role in homology search and strand exchange. Genetic analysis has shown that among members of its epistasis group, RAD52 alone is required for recombination between direct repeats yielding deletions. Very little has been discovered about the biochemical roles and structure of the Rad52 protein. RESULTS: Purified Rad52 protein binds to both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). Electron microscope observations revealed that Rad52 molecules form multimeric rings. An increase in the intensity of fluorescence when Rad52 is bound to epsilonDNA showed an alteration of the structure of ssDNA. RPA was binding to Rad52 and enhanced the annealing of complementary ssDNA molecules. This enhancement was not observed in Escherichia coli SSB protein or T4 phage gp32 protein. CONCLUSION: Rad52 forms a ring-like structure and binds to ssDNA. Its structure and DNA binding properties are different from those of Rad51. The interaction of Rad52 with RPA plays an important role in the enhancement of annealing of complementary ssDNAs. We therefore propose that Rad52 mediates the RAD51-independent recombination through an ssDNA annealing, assisted by RPA.

DNA Replication↗

PubMed1998

c-erbB-2 protein is expressed in hepatolithiasis and cholangiocarcinoma.

AIMS: The c-erbB-2 proto-oncogene encodes a transmembrane protein which is highly homologous to epidermal growth factor receptor. Overexpression of this c-erbB-2 protein has been reported in many human carcinomas, including breast carcinoma. However, there have been few studies of the expression of c-erbB-2 in cholangiocarcinoma and hepatolithiasis, a condition occasionally associated with cholangiocarcinoma. METHODS AND RESULTS: In this study, we evaluated immunoreactivity for the c-erbB-2 protein in human cholangiocarcinomas (n = 47), hepatolithiasis (n = 20), fetal livers (n = 36) and normal adult livers (n = 6). In normal adult livers and fetal livers, expression of c-erbB-2 protein could not be detected in hepatocytes or intrahepatic biliary cells. In hepatolithiasis, there was overexpression of c-erbB-2 in 15/20 (75%). The expression was found with a membranous pattern on the proliferated intrahepatic bile ducts and proliferated intrahepatic peribiliary glands around the bile ducts containing stones. Hepatocytes were negative for c-erbB-2 protein. Moreover, the biliary cell expression of the c-erbB-2 protein correlated significantly with Ki67 labelling index. On the other hand, aberrant expression of c-erbB-2 was found in 33/47 (70%) cholangiocarcinomas. The c-erbB-2 expression in cholangiocarcinomas did not correlate with Ki67 labelling index or p53 expression. CONCLUSIONS: These results indicate that aberrant expression of c-erbB-2 protein is found in cholangiocarcinoma and also in noncancerous biliary proliferative lesions such as hepatolithiasis. These findings also suggest that c-erbB-2 oncogene participates not only in cholangiocarcinogenesis but also in biliary cell proliferation in non-neoplastic conditions.

Adult↗

PubMed1998

Ca2+-dependent K+ currents induced by muscarinic receptor activation in guinea pig adrenal chromaffin cells.

The characteristics of the outward current (I(out)) induced by muscarine were examined by using the whole-cell patch-clamp technique with a K+-containing pipette solution in combination with fura-2 microfluorometry in guinea pig chromaffin cells. Muscarine caused a transient increase in the cytosolic Ca2+ concentration ([Ca2+]i) and activated an I(out) with a reversal potential close to a K+ equilibrium potential. Under symmetric K+ conditions, muscarine produced a transient inward current and an increase in [Ca2+]i at -60 mV. At -15 mV, apamin and charybdotoxin, respective SK and BK channel blockers, decreased the I(out) but scarcely affected the [Ca2+]i response to muscarine. Muscarine produced an I(out) and an increase in [Ca2+]i even after a removal of external Ca2+ and in the presence of Co2+, indicating that these responses are mediated by Ca2+ release from intracellular stores. The I(out) evoked by the Ca2+ release was much smaller than that evoked by the voltage-dependent Ca2+ influx, even when similar [Ca2+]i changes assessed by fura-2 microfluorometry occurred. Inositol 1,4,5-trisphosphate (InsP3) applied intracellularly and the photolysis of caged InsP3 each evoked current changes similar to those induced by muscarine. These results indicate that the I(out) evoked by muscarinic stimulation is mediated by Ca2+-dependent K+ channels (probably BK and SK channels), which are activated by Ca2+ released from intracellular Ca2+ stores in guinea pig chromaffin cells.

Animals↗

PubMed1998

Coronary vascular bed perfusion with a polyethylene glycol-modified hemoglobin-encapsulated liposome, neo red cell, in rats.

Whether hemoglobin (Hb) encapsulated liposomes have vasoconstrictive activity remains controversial. We therefore examined the vascular activity of a liposome Hb, Neo red cell (NRC), in a simple in vitro model of Langendorff perfusion of the rat heart using Krebs-Henseleit (KH) solution as the perfusate. In the KH solution, NRC (Hb at 1 mg/ml), however, induced an immediate and abnormal increase in perfusion pressure. Histological examinations revealed that embolisms were the likely cause of this disturbance. Inorganic crystals formed by the mixing of NRC with the perfusate were a possible source of the embolisms. We found that the addition of bovine serum albumin to the perfusate was effective in avoiding embolic events. This protocol was used to compare the vasoconstrictive properties of unmodified bovine Hb and NRC. Unmodified bovine Hb (1 mg/ml) caused an increase in perfusion pressure and a decrease in the duration of bradykinin-induced relaxation. In contrast, NRC (Hb at 1 mg/ml) had no such vasoconstrictive effects. These results provide the first information regarding perfusion of the circulatory vascular bed by NRC and further evidence that the encapsulation of Hb into liposomes is an effective approach to modulate Hb-related vasoconstrictive activity.

Animals↗

PubMed1998

Changes in plasma alpha 1-acid glycoprotein concentration and selected immune response in broiler chickens injected with Escherichia coli lipopolysaccharide.

1. Changes in plasma alpha 1-acid glycoprotein (AGP) concentration and immune responses following Escherichia coli lipopolysaccharide (LPS) injection were studied in broiler chickens. 2. Higher plasma AGP concentrations were observed from 12 to 48 h after a single injection of LPS. 3. The highest concentration of plasma AGP was observed on day 2 followed by a gradual decrease in chicks injected with 150 micrograms/kg body weight of LPS every day for 13 d. 4. Plasma AGP concentration in chicks injected daily with LPS at 900 micrograms/kg body weight for 13 d increased on day 2, and decreased on day 4 to the concentration found before the injection. The concentration increased again on day 10. 5. Changes in plasma interleukin-1 (IL-1) like activity were similar to those in plasma AGP concentration when LPS was injected daily at 900 micrograms/kg body weight for 3 d. 6. Responses of blood mononuclear cell (MNC) proliferation to mitogen or concanavalin A, (Con A), and pokeweed mitogen (PWM) were positively correlated with changes in plasma AGP concentration. 7. The results suggest that plasma AGP concentration could be used as a positive indicator of changes in blood MNC proliferation to a mitogen and in plasma IL-1 like activity.

Animals↗

PubMed1998

Surgical treatment of distal cervical internal carotid artery aneurysm.

We report on a 55-year-old male with an internal carotid artery aneurysm at the level of the second cervical vertebra. Since ant-coagulation therapy failed to prevent the ischemic attack, aneurysmectomy with arterial reconstruction was performed. Vertical mandibular osteotomy allowed a wide working space in deep operative field. This technique is considered to be useful in surgery for aneurysms of the extracranial distal internal carotid artery.

Aneurysm↗

PubMed1998

Suppressive effects of nimesulide, a selective inhibitor of cyclooxygenase-2, on azoxymethane-induced colon carcinogenesis in mice.

The effects of nimesulide, a selective inhibitor of cyclooxygenase-2 (COX-2) on azoxymethane (AOM)-induced colon carcinogenesis were investigated in mice. AOM at a dose of 10 mg/kg body wt was administered to male ICR mice once a week for 6 weeks. The animals were fed on AIN-76A powder diet containing nimesulide at doses of 200 or 400 p.p.m., starting the day before the first carcinogen treatment until the end of the experiment, at week 30. Administration of nimesulide reduced the incidence of colon carcinomas to 32 and 25% for the AOM + 200 and 400 p.p.m. nimesulide groups, respectively, compared with the AOM + basal diet group (50%). Multiplicities of colon carcinomas in the 200 and 400 p.p.m. nimesulide-treated groups were 0.70 +/- 0.28 and 0.35 +/- 0.11, respectively, being significantly smaller than the AOM alone value (1.79 +/- 0.47). The sizes of the colon carcinomas in the nimesulide-treated groups were also decreased. No significant influence on liver and lung tumor development was apparent. Thus, nimesulide exerted a suppressive effect on AOM-induced colon carcinogenesis in mice.

Animals↗

PubMed1998

In vivo confocal imaging of corneal neovascularization.

PURPOSE: To investigate the cellular dynamics of vessel formation during corneal neovascularization in the living eye by confocal microscopy. METHODS: Corneal neovascularization was initiated by placing a 7-0 silk suture through the corneal stroma 3 mm from the limbus at the 12 o'clock position in both eyes of 10 New Zealand white rabbits. The corneas were examined for vessel ingrowth at intervals from 1 to 15 days after suture placement using a tandem scanning confocal microscope with a 20X water immersion objective, as well as a slit-lamp biomicroscope. Changes in the limbal vessels were recorded on videotape for later analysis. As early vessel growth appeared to be associated with corneal nerves, the total number of sprouts and the number of sprouts along nerves were counted in confocal images, and the results analyzed for statistical significance. Vessel growth and the structural relationship between vascular buds and the deep stromal nerves were examined by light and transmission electron microscopy. RESULTS: The early events of cell migration from the limbal microvessels were found to be associated with the deep stromal nerves; although this association was easily visualized by confocal microscopy, it could not be documented by slit-lamp biomicroscopy. By 18 h after suture placement, the limbal vessels were dilated and the first vascular buds appeared as short, pointed, or flat-topped protrusions from the deep limbal capillaries. By 96 h, the capillary buds had increased in density and had begun to form lumens. Movement of red blood cells was established between 72 and 80 h after the first signs of bud formation, at the same time that cells of immune origin were seen. Confocal microscopy revealed and transmission electron microscopy verified that new bud formation began with the formation of vascular tubes by endothelial migration along the deep stromal nerves. The total number of sprouts and the number of sprouts associated with stromal nerves were similar on days 1 and 2 but differed on days 3-7, suggesting an association between sprouts and nerves in the early stages of neovascularization. CONCLUSION: Using real-time white light confocal microscopy, we were able, for the first time, to observe the process of corneal neovascularization in the living eye, from the earliest stages within hours after initiation to 2 weeks. The deep stromal nerves appear to serve as a focus for the growth of new vessels, by attracting and supporting vessel growth and/or by providing a potential space for movement of the endothelial cells. Confocal microscopy may provide a new approach to achieving a better understanding of the mechanisms involved in corneal neovascularization.

Animals↗

PubMed1998

Characterization of fibrous retrocorneal membrane by confocal microscopy.

PURPOSE: To study the appearance of a fibrous retrocorneal membrane as seen by confocal microscopy. METHODS: A 67-year-old white woman with a history of multiple ocular surgeries, including repeated penetrating keratoplasties for aphakic bullous keratopathy, developed a retrocorneal membrane in the right eye. The membrane was first noticed 3 years after the last corneal transplant and remained stable subsequently. The patient was examined by in vivo white light tandem-scanning confocal microscopy. RESULTS: At the level of the retrocorneal membrane, confocal microscopy disclosed the presence of a hyperreflective fibrous-appearing layer. Normal endothelial cells could not be found. Anterior to the hyperreflective layer, activated keratocytes were identified. CONCLUSION: Confocal microscopy may allow noninvasive diagnosis of fibrous retrocorneal membrane. Additionally, our data suggest that the posterior keratocytes might play a role in the production and deposition of fibrous tissue.

Aged↗

PubMed1998

Neuroprotective effect of an antioxidant, ebselen, in patients with delayed neurological deficits after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: The effect of ebselen, a seleno-organic compound with antioxidant activity through a glutathione peroxidase-like action, on the outcome of subarachnoid hemorrhage was evaluated in a multicenter placebo-controlled double-blind clinical trial. METHODS: Patients who suffered aneurysmal subarachnoid hemorrhages of Hunt and Kosnik Grades II through IV at admission and were able to start drug treatment within 96 hours of the ictus were enrolled. Early surgery was performed whenever possible. Oral administration of ebselen granules suspended in water (150 mg, twice a day) or placebo was started immediately after admission and continued for 2 weeks. The major end points were the Glasgow Outcome Scale at 2 weeks, 1 month, and 3 months after the start of treatment. The incidence of delayed ischemic neurological deficits clinically diagnosed as resulting from vasospasm and the incidence and extent of low-density areas on postoperative computed tomographic scans were also studied as secondary outcome measures. RESULTS: Intent-to-treat analysis of the 286 patients enrolled in the trial (145 patients administered ebselen and 141 administered placebo) revealed that the incidence of clinically diagnosed delayed ischemic neurological deficits was unaltered. There were 52 (receiving ebselen) and 58 (receiving placebo) patients with delayed deficits; however, a significantly better outcome was observed after ebselen treatment than after placebo (P = 0.005, chi2 test). There was a corresponding decrease in the incidence and extent of low-density areas (P = 0.032, Wilcoxon rank sum test). CONCLUSION: Ebselen reduced brain damage in patients with delayed neurological deficits after subarachnoid hemorrhage and may be a promising neuroprotective agent.

Aged↗

PubMed1998

Inhibition of enhanced toxin production by Clostridium difficile in biotin-limited conditions.

Production of toxins A and B by Clostridium difficile is enhanced in a defined medium with biotin-limited conditions. In the present study compounds inhibitory to enhanced toxin production by a C. difficile strain were examined. Increases in biotin concentration from 0.05 nM to 50 nM accelerated growth and inhibited enhanced toxin production. Asparagine, glutamic acid and glutamine (10 mM) showed an effect on growth and toxin production similar to that of biotin. Lysine (10 mM) suppressed growth and inhibited toxin production. Addition of these toxin-inhibitory compounds within an incubation period of 2 days inhibited the enhanced toxin production, but later addition showed only slight inhibition of toxin production. Amino acids contained in the defined medium under the biotin-limited conditions were actively utilised in the presence of the three toxin-inhibitory amino acids, but in the presence of lysine, amino-acid utilisation was suppressed. Different mechanisms of action of these toxin-inhibitory molecules, which may be divided into excess biotin, asparagine-glutamic acid-glutamine group, and lysine, are discussed.

Amino Acids↗

PubMed1998

Sleep problems in the aged in relation to senility.

As a part of an epidemiologic survey of dementia in a community of aged persons, correlation between sleep complaints and physical illness and senility were studied. A total of 3302 randomly sampled aged individuals(aged > or = 65 years) were studied using a questionnaire. In this sample the prevalence of poor sleep and habitual snoring did not increase with age. The prevalence of excessive daytime sleepiness showed an increase with age. Male predominance of habitual snoring and female predominance of poor sleep were observed. Female predominance of excessive daytime sleepiness was noted among the aged 70 and over. Age-related excessive daytime sleepiness was significantly correlated with senility.

Aged↗

PubMed1998

Differences in arousal response between aged and middle-aged patients with obstructive sleep apnea syndrome.

The aim of this study is to show the clinical significance of the differences in arousal response at a termination of apnea/hypopnea between aged and middle-aged patients with obstructive sleep apnea syndrome (OSAS). We polygraphically assessed electrocardiographic (ECG) and electroencephalographic (EEG) arousal. Electrocardiographic arousal was defined as an abrupt increase in heart rate at a termination of apnea/hypopnea. Our findings showed that EEG and ECG arousal at a termination of apnea/hypopnea were significantly suppressed in aged patients with OSAS, which might provide useful information on the pathophysiology, of OSAS.

Adult↗

PubMed1998

Daytime sleepiness and automobile accidents in patients with obstructive sleep apnea syndrome.

We evaluated the rate of automobile accidents and daytime sleepiness using the Epworth sleepiness scale (ESS) in 44 patients with obstructive sleep apnea syndrome (OSAS). We defined the automobile accident score as a sum of two points for every one automobile accident and one point for every near-miss accident. Automobile accidents and near-misses were found in 54.5% and 50.0% in patients with OSAS. Automobile accident score was significantly correlated with the ESS score (r=0.56, P < 0.01). Our findings suggest that ESS score may be useful in detecting patients with the potential risk of automobile accidents associated with daytime sleepiness.

Accidents, Traffic↗

PubMed1998

Inhibitory effects of tacrine and physostigmine on catecholamine secretion and membrane currents in guinea-pig adrenal chromaffin cells.

The effects of tacrine and physostigmine on catecholamine secretion induced by veratridine and high K+, and on voltage-dependent Na+ and Ca2+ currents, were investigated in guinea-pig adrenal chromaffin cells. In perfused adrenal glands, tacrine (100 microM) caused an inhibition of veratridine-induced catecholamine secretion, but physostigmine (100 microM) did not. In dispersed cells, both tacrine (1 microM-1 mM) and physostigmine (1 microM-1 mM) decreased catecholamine secretion induced by veratridine in a dose-dependent manner. The inhibitory effect of tacrine was much greater than that of physostigmine. Tacrine alone at a high concentration (such as 1 mM) caused a substantial increase in catecholamine secretion by itself and completely abolished the veratridine-induced secretory response in dispersed cells. High-concentration physostigmine showed a similar effect, but to a much lesser extent. The high K+ (46.2 mM)-evoked catecholamine secretion from dispersed cells was not affected by tacrine (1-100 microM) or physostigmine (1 microM-1 mM). In fura-2 loaded cells, tacrine (100 microM) almost abolished [Ca2+]i rise induced by veratridine, but only slightly reduced that evoked by high K+. In voltage-clamped cells, tacrine (300 microM) depressed the voltage-dependent Na+ and Ca2+ current by about 93% and 69%, and physostigmine (300 microM) depressed them by about 30% and 17%, respectively. These results suggest that tacrine decreases the veratridine-induced catecholamine secretion primarily by inhibiting the voltage-dependent Na+ channels rather than the Ca2+ channels. Physostigmine acts in a manner similar to tacrine, but its potency is much lower than that of tacrine.

Adrenal Glands↗