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91.
Prof. Dr. Werner Müller 《当今生物学》2013,43(1):40-45
Therapeutic use of stem cells Here the hematopoetic system of blood‐ and immune cell renewal is reviewed. Curing of chronic leucemias and malignant lymphomas is the most successful stem cell based therapy up to date. However, mismatches of histocompatibility‐complexes (HLA‐types) between receiver and donor set narrow limits to such therapies. Whether other diseases such as Parkinson could be cured by infusion of stem cells is still in question. 相似文献
92.
N-Acetylmuramyl-dipeptide and tripeptide derivatives containing at the C-terminus a masked thiol function, i.e. the S-tert-butylthiocysteamine residue, were synthesized via direct condensation of N-acetylmuramic acid with the peptide moiety using the dicyclohexylcarbodiimide/N-hydroxysuccinimide procedure. Reduction with tributylphosphine in aqueous organic media generates the free thiol function for a selective conjugation of these immunomodulants with target molecules via unsymmetrical disulfide bridging with a second thiol group by the sulfenohydrazide procedure or via thio-ether linkage by the addition to maleimido--or aziridine-derivatives. 相似文献
93.
Wounding of quiescent white potato tuber tissue enhances chromatin-boundprotein phosphokinase activity, which exhibits two distinctphases during wound-healing. A moderate activation of the enzymesup to 20 hr after injury is followed by a dramatic increasein activity with a peak at 50 hr. This time-course resemblesthat of chromatinbound DNA-dependent RNA polymerase with a peakin activity at about 48 hr after wounding. The kinases phosphorylateendogenous proteins as well as added histones, phosvitin andcasein. The incorporated phosphate is stable under standardassay conditions, indicating the absence of protein phosphatases.Sensitivity of the incorporated phosphate toward trypsin andalkali, but not DNase, RNase, hydroxylamine or succinic acidpoints to seryl- and threonyl-bonds and proteins as acceptormolecules. Kinases from resting tissues are only weakly stimulatedeven by 100 mM MgCl2, those from wounded tissues exhibit pronouncedMg$$-optima at 510 mM with endogenous proteins, phosvitinand casein and 50 mM MgCl2 with histones. Wounding also increasesthe sensitivity of the kinases toward p-hydroxymercuribenzoate. Chromatin preparations from both resting and wounded tissuescontain about 40 protein bands after polyacrylamide disc gelelectrophoresis. In vitro phosphorylation of these proteinsin chromatin from quiescent tissues is comparably low and uniform.Wounding induces changes in the protein and phosphorylationpattern with a general enhancement of phosphorylative capacityand preferential phosphorylation of low molecular weight proteins. (Received August 10, 1981; Accepted November 18, 1981) 相似文献
94.
Summary Mature spinach plants were held in the dark for several days. The photochemical activities and the activity of some enzymes related to NADP reduction were follwed in the chloroplasts isolated from leaves after dark starvation. Photosystem-II, measured by reduction of DPIP, remained stable during 6 days of darkening. The decrease of NADP reduction which appeared after 2 days of starvation was found to be due to protein autolysis rather than inactivation of the photosystems. The stability of photosystem-I was demonstrated by reactivation of NADP reduction after addition of purified ferredoxin and ferredoxin-NADP-reductase. After 4 days of starvation the restoration of the NADP reduction required in addition another, low-molecular-weight factor. From the isolation procedure and from its properties this factor is assumed to be identical with FRS. However, even in the presence of FRS only half of the total activity is restored after 7 days. The activity of the NADP-reducing system is restored in vivo when plants kept for 7 days in the dark are again illuminated.Abbreviations NADP
nicotinamide-adenine-dinucleotide phosphate
- DPIP
2,6-dichlorophenolindophenol
- DCMU
(3,4-dichlorophenyl)-1,1-dimethylurea
- FRS
ferredoxin-reducing-substance 相似文献
95.
Rat serum, in which the complement system had been activated by incubation with zymosan, increased the glucose and lactate output, and reduced and redistributed the flow in isolated perfused rat liver clearly more than the control serum. Heat inactivation of the rat serum prior to zymosan incubation abolished this difference. Metabolic and hemodynamic alterations caused by the activated serum were dose dependent. They were almost completely inhibited by the cyclooxygenase inhibitor indomethacin and by the thromboxane antagonist 4-[2-(4-chlorobenzesulfonamide)-ethyl]-benzene-acetic acid (BM 13505), but clearly less efficiently by the 5'-lipoxygenase inhibitor nordihydroguaiaretic acid and the leukotriene antagonist N-(3-[3-(4-acetyl-3-hydroxy-2-propyl-phenoxy)-propoxy]-4-chlorine-6-meth yl- phenyl)-1H-tetrazole-5-carboxamide sodium salt (CGP 35949 B). Control serum and to a much larger extent complement-activated serum, caused an overflow of thromboxane B2 and prostaglandin F2 alpha into the hepatic vein. It is concluded that the activated complement system of rat serum can influence liver metabolism and hemodynamics via release from nonparenchymal liver cells of thromboxane and prostaglandins, the latter of which can in turn act on the parenchymal cells. 相似文献
96.
97.
V Carillet P Morlière J C Mazière G Hüppe R Santus L Dubertret 《Biochimica et biophysica acta》1990,1055(2):102-106
Etretinate or acitretin are efficiently delivered to cultured human fibroblasts in the presence of low density lipoproteins, high density lipoproteins or human serum albumin. In contrast to acitretin, delivery of etretinate to fibroblasts is more efficiently achieved with human serum albumin than with lipoproteins. The uptake of etretinate and acitretin via low density lipoproteins delivery, does not take place via the low density lipoprotein-receptor endocytotic pathway but mostly through a passive exchange with the plasma membrane. However, in contrast to acitretin, the exchange of etretinate seems to occur alter binding of etretinate-loaded low density lipoproteins to the apolipoprotein B receptors. No differences are observed in binding, internalization and degradation of native, etretinate-loaded low density lipoproteins and acitretin-loaded low density lipoproteins, suggesting that the presence of these retinoids in low density lipoproteins does not alter their processing by the cells. Furthermore, the presence of these retinoids in the cells does not notably affect, under our experimental conditions, the catabolism of native low density lipoproteins. 相似文献
98.
Summary Phage adsorption tests and transfection by electroporation were carried out to decide whether phage-resistance in Lactococcus lactis subsp. lactis strain 4513-5 is based on intracellular or extracellular mechanisms. Using high voltage (12.5 kV/cm) electroporation, untreated phage DNA was introduced into phage-sensitive and phage-resistant cells. Since phages showed low adsorption frequencies on resistant bacteria, resistance is localized in the cell wall preventing phage DNA from entering the cell. This is the only mechanism responsible for the resistance of L. lactis subsp. lactis 4513-5 against its homologous phage P4513-K12 and non-homologous phages P05M-13 and P05M-47, but not against phage P530-7 and phage P530-12. In the case of the latter two phage strains, intracellular resistance mechanisms are involved and discussed. 相似文献
99.
100.
John A. Nyakatura Vivian R. Allen Jonas Laustr?er Amir Andikfar Marek Danczak Hans-Jürgen Ullrich Werner Hufenbach Thomas Martens Martin S. Fischer 《PloS one》2015,10(9)
Orobates pabsti, a basal diadectid from the lower Permian, is a key fossil for the understanding of early amniote evolution. Quantitative analysis of anatomical information suffers from fragmentation of fossil bones, plastic deformation due to diagenetic processes and fragile preservation within surrounding rock matrix, preventing further biomechanical investigation. Here we describe the steps taken to digitally reconstruct MNG 10181, the holotype specimen of Orobates pabsti, and subsequently use the digital reconstruction to assess body mass, position of the centre of mass in individual segments as well as the whole animal, and study joint mobility in the shoulder and hip joints. The shape of most fossil bone fragments could be recovered from micro-focus computed tomography scans. This also revealed structures that were hitherto hidden within the rock matrix. However, parts of the axial skeleton had to be modelled using relevant isolated bones from the same locality as templates. Based on the digital fossil, mass of MNG 10181 was estimated using a model of body shape that was varied within a plausible range to account for uncertainties of the dimension. In the mean estimate model the specimen had an estimated mass of circa 4 kg. Varying of the mass distribution amongst body segments further revealed that Orobates carried most of its weight on the hind limbs. Mostly unrestricted joint morphology further suggested that MNG 10181 was able to effectively generate propulsion with the pelvic limbs. The digital reconstruction is made available for future biomechanical studies. 相似文献