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91.
Mamoun Younes Robert T. Jensen Jerry D. Gardner 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1987,930(3):410-418
When dispersed acini from mouse pancreas are first incubated with cholecystokinin octapeptide, washed and then reincubated with no additions there is significant stimulation of amylase secretion during the second incubation (residual stimulation of enzyme secretion). Cholecystokinin-induced residual stimulation of enzyme secretion is modified, but not abolished, by reducing the temperature of the first incubation from 37°C to 4°C. Measurement of binding of 125I-labeled cholecystokinin octapeptide indicated that maximal cholecystokinin induced residual stimulation of enzyme secretion occurs when 12–20% of cholecystokinin receptors are occupied by cholecystokinin octapeptide. Moreover, maximal cholecystokinin-induced residual stimulation of amylase secretion is 25% greater than maximal cholecystokinin-induced direct stimulation of amylase secretion. Cholecystokinin tetrapeptide, which causes the same maximal direct stimulation of amylase secretion as does cholecystokinin octapeptide, causes a maximal residual stimulation of enzyme secretion that is only 30% of that caused by a maximally effective concentration of cholecystokinin octapeptide. Adding dibutyryl cyclic GMP to the second incubation can reverse the residual stimulation caused by adding cholecystokinin to the first incubation. The pattern and extent of the dibutyryl cyclic GMP-induced reversal of residual stimulation varies, depending on the temperature and concentration of cholecystokinin octapeptide in the first incubation. The present results are compatible with the hypothesis that mouse pancreatic acini possess two classes of cholecystokinin receptors. One class has a relatively high affinity for cholecystokinin and produces stimulation of enzyme secretion; the other class has a relatively low affinity for cholecystokinin and produces inhibition of enzyme secretion. 相似文献
92.
Sara Rasoul-Amini Elham Fotooh-Abadi Younes Ghasemi 《Journal of applied phycology》2011,23(6):975-981
This paper reports the biotransformation of carvone, limonene, β-pinene, thymol, and linalool using whole-cell-immobilized
microalgal strains isolated from paddy fields of Iran. The strains was recognized by morphological characterization and assigned
according to amplified 16S/18S rRNA genes by PCR. Ten unialgal strains including Chlorella, Oocystis, Chlamydomonas, and Synechococcus were immobilized in calcium alginate beads. After a 24-h incubation with substrates, characterization and identification
of biotransformation products were done by GC/MS. None of the isolated immobilized microalgae converted β-pinene. In contrast,
most of these strains biotransformed carvone and limonene to the related compounds. Some strains only reduced the C = C double
bond to yield the dihydrocarvone isomers while others reduced the ketone to give the dihydrocarveol. The transformation ratio
showed that Oocystis sp. MCCS 033 and Synechococcus sp. MCCS 035 produced dihydrocarvone isomers with the highest efficiency. Furthermore, limonene was converted into a mixture
of five corresponding products and the maximum yield was 52.1% for carvone, the bioconverted product. Only one strain, Synechococcus sp. MCCS 034, oxidized thymol, and the product obtained from thymol was thymoquinone. Also, linalooloxide isomers and dihydrolinalool
were obtained from linalool, and finally dihydrolinalool was the main product. These results showed a novel conversion pathway
of linalool-forming dihydrolinalool. 相似文献
93.
94.
95.
Fe2+-supported in vivo lipid peroxidation induced by compounds undergoing redox cycling 总被引:1,自引:0,他引:1
Treatment of male mice with the redox cycling compounds nitrofurantoin, paraquat, diquat or menadione failed to elicit in vivo lipid peroxidation as evidenced by ethane exhalation. The first three led to an enhanced ethane production, however, when the animals were pretreated with a low dose of Fe2+. While GSH-depletion by phorone pretreatment alone had no influence on the in vivo lipid peroxidation as evidenced by ethane expiration in the presence of either compound, the combined treatment with phorone, Fe2+ and nitrofurantoin, paraquat or diquat led to a further enhancement of ethane exhalation. These results indicate that redox cycling compounds do not initiate lipid peroxidation by themselves, but are well capable of stimulating the iron-induced LPO. 相似文献
96.
97.
Younes SA Csire M Palyi B Mikala G Vályi-Nagy I Cseh I Benczik M Jeney C Takács T Simon E Fülöp V Berencsi G Fekete G Visy M 《Acta microbiologica et immunologica Hungarica》2007,54(3):279-303
Pregnant women were examined following healthy pregnancies at term. Amniotic fluids were sampled before arteficial rupture of membranes using closed vacutainer system. Blood samples were also taken from the pregnants simultaneously. Endotoxin concentrations of amniotic fluids were tested by the semiquantitative Limulus amebocyte lysate. Both amniotic fluids and blood samples were tested for the presence of DNA of lymphotropic human herpesviruses. The DNA of human papillomaviruses were tested only in the amniotic fluid samples. One-third of the amniotic fluids tested were found to contain measurable amounts of endotoxin. Lymphotropic herpesvirus DNA was deteced in every fourth amniotic fluid sample and in every 8th blood sample. The prevalence of papillomaviruses was 7 of 96 samples. No significant correlation was found between the presence of endotoxin and viruses in the amniotic fluids. Epstein-Barr virus, human cytomegalovirus and human herpesvirus type 7 were found more frequently in the amniotic fluids than in blood samples (7 to 1). The prevalence of human herpesvirus 6 and 8 was higher in the blood samples than that in the amniotic fluids. The mean weight of the neonates were not impaired significantly by the presence of either viruses or endotoxin. Possible post partum consequences, i.e. partial immunotolerance to viruses is discussed. 相似文献
98.
Thérèse S Lapperre Jacob K Sont Annemarie van Schadewijk Margot ME Gosman Dirkje S Postma Ingeborg M Bajema Wim Timens Thais Mauad Pieter S Hiemstra 《Respiratory research》2007,8(1):85-9
Background
Chronic Obstructive Pulmonary Disease (COPD) is associated with bronchial epithelial changes, including squamous cell metaplasia and goblet cell hyperplasia. These features are partially attributed to activation of the epidermal growth factor receptor (EGFR). Whereas smoking cessation reduces respiratory symptoms and lung function decline in COPD, inflammation persists. We determined epithelial proliferation and composition in bronchial biopsies from current and ex-smokers with COPD, and its relation to duration of smoking cessation.Methods
114 COPD patients were studied cross-sectionally: 99 males/15 females, age 62 ± 8 years, median 42 pack-years, no corticosteroids, current (n = 72) or ex-smokers (n = 42, median cessation duration 3.5 years), postbronchodilator FEV1 63 ± 9% predicted. Squamous cell metaplasia (%), goblet cell (PAS/Alcian Blue+) area (%), proliferating (Ki-67+) cell numbers (/mm basement membrane), and EGFR expression (%) were measured in intact epithelium of bronchial biopsies.Results
Ex-smokers with COPD had significantly less epithelial squamous cell metaplasia, proliferating cell numbers, and a trend towards reduced goblet cell area than current smokers with COPD (p = 0.025, p = 0.001, p = 0.081, respectively), but no significant difference in EGFR expression. Epithelial features were not different between short-term quitters (<3.5 years) and current smokers. Long-term quitters (≥3.5 years) had less goblet cell area than both current smokers and short-term quitters (medians: 7.9% vs. 14.4%, p = 0.005; 7.9% vs. 13.5%, p = 0.008; respectively), and less proliferating cell numbers than current smokers (2.8% vs. 18.6%, p < 0.001).Conclusion
Ex-smokers with COPD had less bronchial epithelial remodelling than current smokers, which was only observed after long-term smoking cessation (>3.5 years).Trial registration
NCT00158847 相似文献99.
100.