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991.
Variants of creatine kinase-MM (variant of ATP:creatine N-phosphotransferase, EC 2.7.3.2), present in human heart and skeletal muscle, have been purified to homogeneity using DEAE-Sepharose column chromatography and column chromatofocusing techniques. Creatine kinase-MM I-IV were present in both heart and skeletal muscle, while MM-V was found only in heart. The number, ratio and elution profile of the variants during chromatofocusing remained identical even when they were purified in the presence of proteinase inhibitors. MM-I-V, on chromatofocusing, were eluted at pH 8.3, 7.9, 7.6, 7.2 and 6.8, respectively. Isoelectric focusing revealed the pI of MM-I-V to be 7.2, 6.9, 6.7, 6.4 and 6.2. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis showed a doublet pattern for creatine kinase-MM variants III-V. However, polyacrylamide gel electrophoresis without SDS indicated homogeneity because each variant showed a single band. The doublet pattern observed in the presence of SDS may reflect the presence of two subunits of slightly different mass. 相似文献
992.
H. Levesque P. Delepelaire P. Rouzé J. Slightom D. Tepfer 《Plant molecular biology》1988,11(6):731-744
Analysis of published sequences for Ri TL-DNA (root-inducing left-hand transferred DNA) of Agrobacterium rhizogenes revealed several unsuspected structural features. First, Ri TL-DNA genes are redundant. Using redundancy as a criterion, three regions (left, middle and right) were discerned. The left one, ORFs (open reading frames) 1–7, contains no detectable redundancy. In the middle region a highly diverged gene family was detected in ORFs 8, 11, 12, 13 and 14. The right region contains an apparently recent duplication (ORF 15 =18+17). We interpret the phenomenon of redundancy, particularly in the central region that encodes the transformed phenotype, to be an adaptation that ensures function in a variety of host species. Comparison of Ri TL-DNA and Ti T-DNAs from Agrobacterium tumefaciens revealed common structures, unpredicted by previous nucleic acid hybridization studies. Ri TL-DNA ORF 8 is a diverged Ti T-DNA tms1. Both Agrobacterium genes consist of a member of the diverged gene family detected in the central part of the Ri TL-DNA, but fused to a sequence similar to iaaM of Pseudomonas savastonoi. Other members of this gene family were found scattered throughout Ti T-DNA. We argue that the central region of Ri and the part of Ti T-DNA including ORFs 5–10 evolved from a common ancestor. We present the hypothesis that the gene family encodes functions that alter developmental plasticity in higher plants. 相似文献
993.
Freund B. J.; Joyner M. J.; Jilka S. M.; Kalis J.; Nittolo J. M.; Taylor J. A.; Peters H.; Feese G.; Wilmore J. H. 《Journal of applied physiology》1987,63(3):930-936
Thermoregulation and cardiovascular drift were studied under conditions of prolonged exercise in a warm environment (dry bulb temperature 31.7 +/- 0.3 degrees C, rh 44.7 +/- 4.7%) during beta-adrenergic blockade. Fourteen subjects performed 90-min rides on a cycle ergometer at a work rate equivalent to 40% of their control maximal O2 uptake under each of three treatments provided in a randomized double-blind manner: atenolol (100 mg/day), propranolol (160 mg/day), and a placebo. Exercise during the propranolol trial resulted in significantly higher forearm vascular resistance values and significantly lower forearm blood flows (FBF) compared with the placebo trial. However, the significantly lower FBF during propranolol did not significantly alter the rectal temperature (Tre) response to prolonged exercise. In addition, both beta-blockers produced lower FBF for any given Tre, suggesting that beta-adrenergic blockade affects FBF through nonthermal factors. The slight differences in Tre, despite the large differences in FBF between the various treatments, are apparently the result of an enhanced sweat loss and a lower mean skin temperature during exercise with beta-blockade. The uncoupling of FBF and sweat loss provides evidence of independent regulation. The reduction in FBF at any given Tre was concomitant to lower blood pressure values during beta-blockade and suggests that baroreflexes provide significant input to the control of skin blood flow when both pressure and temperature maintenance are simultaneously challenged. 相似文献
994.
Summary The sequence of the synthesis and transport of the organic matrix of spicules has been elucidated in the gorgonian Leptogorgia virgulata by use of 3H-aspartic acid as the tracer in electron-microscopic autoradiography. The entire process of matrix synthesis and transport takes approximately 2 h. It seems that the protein moiety of the organic matrix is synthesized in the RER prior to 5 min following the initial 10 min incubation in the tracer. At the 5 min chase the label is moving from the RER to the Golgi complexes where the carbohydrate moiety of the matrix is presumed to be synthesized. At the 5 to 15 min chases the label is transported out of the Golgi complexes via Golgi vesicles. This phase continues for 30 min. From 60 to 120 min the 3H-aspartic acid moves to the spicules. After 120 min the majority of the label has moved into the spicules. Silver grain counts over both multivesicular and electron-dense bodies remain at relatively low and constant levels over 4 h indicating that neither organelle is involved in the synthesis and transport of the organic matrix.Contribution No 512; Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina, Columbia, South Carolina 29208, USA 相似文献
995.
Intrinsic sympathomimetic- and membrane activities of beta-adrenoceptor blocking agents are of little or no clinical significance. A selective blockade of cardiac receptors has important therapeutic consequences, especially in the treatment of patients with obstructive airways diseases. Profound depression of miocardial contractility can be deleterious in patients with cardiac muscle damage and the use of beta-adrenergic blockers with a quantitative selectivity towards chronotropism may become an important consideration. The effects of a number of beta-sympatholytics have been determined on isolated cardiac preparations (beta1-adrenergic receptors) and tracheal preparations (beta2-adrenergic receptors) of guinea-pigs. Results indicate that prindolol is the most selective blocker of the beta1 chronotropic receptors whilst atenolol could be classified as being the most cardioselective beta-adrenergic blocker investigated. Butoxamine, on the other hand, proved to be the most beta2-selective one. 相似文献
996.
Lucia Di Giambattista P. Grimaldi S. Gaudenzi D. Pozzi M. Grandi S. Morrone I. Silvestri A. Congiu Castellano 《European biophysics journal : EBJ》2010,39(6):929-934
We have made a preliminary analysis of the results about the effects on tumoral cell line (lymphoid T cell line Jurkat) induced
by UVB radiation (dose of 310 mJ/cm2) with and without a vegetable mixture. In the present study, we have used two techniques: Fourier transform infrared spectroscopy
(FTIR) and flow cytometry. FTIR spectroscopy has the potential to provide the identification of the vibrational modes of some
of the major compounds (lipid, proteins and nucleic acids) without being invasive in the biomaterials. The second technique
has allowed us to perform measurements of cytotoxicity and to assess the percentage of apoptosis. We already studied the induction
of apoptotic process in the same cell line by UVB radiation; in particular, we looked for correspondences and correlations
between FTIR spetroscopy and flow cytometry data finding three highly probable spectroscopic markers of apoptosis (Pozzi et
al. in Radiat Res 168:698–705, 2007). In the present work, the results have shown significant changes in the absorbance and
spectral pattern in the wavenumber protein and nucleic acids regions after the treatments. 相似文献
997.
998.
M Traczewska D Chmielewska M Ochocka 《Folia haematologica (Leipzig, Germany : 1928)》1985,112(4):525-536
The in vivo effect of thymus factor X (TFX) on the E-rosetting capacity, the absolute peripheral blood lymphocytes and T-cell number per microliter, the skin test reactivity to recall antigens, and the immunoglobulin production was evaluated in 20 children with acute lymphoblastic leukaemia. The in vitro effect of TFX was also tested. The mean percentage of E-rosettes in these patients increased from 50 to 64%. Although absolute peripheral blood lymphocyte and T-cell number per microliter rose significantly, the mean values did not reach those in healthy children. The tests with recall antigens were positive in 13% of patients prior to immunotherapy and 32% following the therapy. The influence of immunotherapy on infectious episodes and on the stabilisation of remission was also evaluated. TFX in vivo appears to restore immunocompetence, decrease infections, and prolong remissions in children with ALL in remission. 相似文献
999.
1000.
Crystals of the steroid-metabolizing enzyme, delta 5-3-ketosteroid isomerase (EC 5.3.3.1) from Pseudomonas testosteroni, exhibit many enzymatic properties. Each enzyme subunit in the lattice binds a competitive inhibitor, progesterone, with the same stoichiometry (1:1) and affinity (KD = 6 X 10(-6) M) as the enzyme in solution. Another competitive inhibitor, 19-nortestosterone, competes with progesterone for the same binding sites in the crystal. The enzyme crystals catalyze the conversion of delta 5- to delta 4-ketosteroids, but because the enzyme is so efficient, and substrate diffusion into the crystal is so slow, substrate cannot penetrate deeply into the crystal before being converted to product. A general theoretical formulation is presented to account for the effects of substrate diffusion into enzyme crystals of different shapes and sizes. The dependence of apparent mean enzyme activity in steroid isomerase crystals as a function of crystal size is shown to be consistent with this theoretical formulation. These inhibitor binding and catalytic properties suggest that the enzyme is in an active conformation within these crystals. 相似文献