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1.
N Rakieten B S Gordon A Beaty R W Bates P S Schein F G Standaert 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1976,151(3):632-635
Hypoglycemic rats bearing insulin-secreting islet-cell adenomas produced by the combined action of streptozotocin and nicotinamide were treated with streptozotocin. Antitumor response was demonstrated by elevation of blood glucose, reduction in plasma and tumor IRI, and histopathologic changes in the beta-cell neoplasm. The rodent tumor model may serve as a predictive system for selection and investigation of mechanisms of action of future antitumor agents to be used in the treatment of malignant insulinoma in man. 相似文献
2.
Treatment of asthma by a controlled-release theophylline tablet formulation: a review of the North American experience with nocturnal dosing 总被引:2,自引:0,他引:2
As many as 80 percent of asthmatics experience nighttime or early-morning episodes, which are difficult to treat and potentially fatal. The greater-than-normal amplitude of circadian airflow variation in many asthmatics contributes heavily to the genesis of the early 'morning dip'. Beta-agonists and corticosteroids are of limited usefulness in nocturnal asthma, and slow-release theophylline drugs, while potentially effective, vary in 24-hr blood profile and hence their influence on nocturnal episodes. Traditional 12-hr 'symmetric' theophylline regimens, instead of meeting increased nocturnal demands, may actually produce lower night- than daytime blood levels. On the other hand, appropriately timed administration of a once-daily theophylline drug might provide maximum blood levels when needed and help stabilize 24-hr airflow. Accumulated data, summarized in this review, demonstrate the chronotherapeutic potential of single-daily evening doses of a controlled-release theophylline preparation (Uniphyl 400-mg tablets) in nocturnal and early morning asthma. Nighttime blood concentrations with this regimen were higher than were those with Theo-Dur tablets, B.I.D., in the same total daily doses, or with once-daily morning Uniphyl administration. In fed and fasted subjects, evening administration of Uniphyl 400-mg tablets was well tolerated and did not lead to 'dose dumping.' Clinically, this treatment demonstrated advantages over B.I.D. theophylline, over single-daily morning regimens, and over prior theophylline therapy. Advantages of the evening regimen included better early-morning airflow (without significant decline later in the day), more effective symptom control, better patient acceptance, fewer night awakenings, and the obvious convenience of once-daily dosing. In addition, lung function showed greater stability, throughout the day, with once-daily evening therapy than with traditional 12 hr dosing. Uniphyl 400-mg tablets may be administered once daily to provide maximum blood levels at the time of peak bronchoconstriction, whether at night or during the day. 相似文献
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Urate oxidation by cupric ion (Cu(++)) 总被引:1,自引:0,他引:1
6.
A H Schein 《The Biochemical journal》1966,98(1):311-316
1. When DNA is hydrolysed with formic acid for 30min. at 175 degrees and the hydrolysate is chromatographed on paper with propan-2-ol-2n-hydrochloric acid, in addition to expected ultraviolet-absorbing spots corresponding to guanine, adenine, cytosine and thymine, an ultraviolet-absorbing region with R(F) similar to that of uracil can be detected. Uracil was separated from this region and identified by its spectra in acid and alkali, and by its R(F) in several solvent systems. 2. Cytosine, deoxyribocytidine and deoxyribocytidylic acid similarly treated with formic acid all yielded uracil, as did a mixture of deoxyribonucleotides. 3. Approx. 4% of deoxyribonucleotide cytosine was converted into uracil by the formic acid treatment. 相似文献
8.
Gamogony of Theileria annulata Dschunkowsky & Luhs occurs within the intestine of nymphs of the tick Hyalomma anatolicum excavatum Koch. After the 5th day post repletionem (p.r.) of the ticks spherical and ovoid parasites were found within the intestinal cells. These stages were thought to represent fertilized macrogametes. These underwent a transformation process leading ultimately to the differentiation of a motile stage, the kinete, which leaves the intestinal cells on the 14th-17th day p.r. and penetrates the alveoles of the salivary glands. The transformation of the stationary into a motile stage takes place by formation of a growing protrusion (= anlage) into an inner, enlarging vacuole. During this process the limiting membrane of the vacuole serves as the outer membrane of the developing motile stage, whereas the 2 inner membranes of its pellicle are newly formed. The steps of this differentiation in T. annulata are compared to the process of ookinete formation in haemosporina. 相似文献
9.
Bovine seminal ribonuclease (BS-RNase), a dimeric homologue of RNase A, cleaves both single- and double-stranded RNA and inhibits the growth of tumor cells. Its catalytic activity against double-stranded RNA, either homopolymeric ([3H]polyA/polyU) or mixed sequence, is enhanced by bovine or human recombinant interferon-γ (IFN-γ). Activation is seen with as little as 4–10 interferon units per assay. Enhancing the degradation of double-stranded RNA, an intermediate in the growth cycle of many viruses, could contribute to IFN-γ's ability to control cell growth and induce an antiviral state. 相似文献
10.
Reconstitution in planar lipid bilayers of a voltage-dependent anion-selective channel obtained from paramecium mitochondria 总被引:24,自引:0,他引:24
Stanley J. Schein Marco Colombini Alan Finkelstein 《The Journal of membrane biology》1976,30(1):99-120
Summary We have incorporated into planar lipid bilayer membranes a voltage-dependent, anion-selective channel (VDAC) obtained fromParamecium aurelia. VDAC-containing membranes have the following properties: (1) The steady-state conductance of a many-channel membrane is maximal when the transmembrane potential is zero and decreases as a steep function of both positive and negative voltage. (2) The fraction of time that an individual channel stays open is strongly voltage dependent in a manner that parallels the voltage dependence of a many-channel membrane. (3) The conductance of the open channel is about 500 pmho in 0.1 to 1.0m salt solutions and is ohmic. (4) The channel is about 7 times more permeable to Cl– than to K+ and is impermeable to Ca++. The procedure for obtaining VDAC and the properties of the channel are highly reproducible.VDAC activity was found, upon fractionation of the paramecium membranes, to come from the mitochondria. We note that the published data on mitochondrial Cl– permeability suggest that there may indeed be a voltage-dependent Cl– permeability in mitochondria.The method of incorporating VDAC into planar lipid bilayers may be generally useful for reconstituting biological transport systems in these membranes. 相似文献