Although young adult C3H/HeJ (OH) females do not reject C3H male skin grafts, OH females older than 1 year commonly do so, as also do many thymectomized, young adult C3H females. Therapy With TP5, a synthetic pentapeptide analogue of thymopoietin which has biological properties of the parent molecule, substantially reduced the capacity of aged OH females and of thymectomized, young OH females to reject OH male skin. 相似文献
A soluble protein that interacts with a range of cytokinins was extensively purified from wheat (Triticum aestivum L.) germ. This protein has a Kd for kinetin of 2×10-7 M. The binding of kinetin to the protein is inhibited by low concentrations of synthetic and naturally-occurring cytokinins including N6-benzyladenine, N6-benzyladenosine, kinetin riboside, N6-dimethylallyladenine, N6-dimethylallyladenosine, zeatin, zeatin riboside, N6-dimethyladenine and N6-dimethyladenosine. Adenine, adenosine and several non-N6-substituted adenine derivatives were ineffective as inhibitors of kinetin binding. While N6-butyryl-3,5-cyclic AMP, N6,2-O-dibutyryl-3,5-cyclic AMP and 2,3-cyclic AMP inhibited binding of kinetin to the protein, 3,5-cyclic AMP was ineffective. The kinetin-binding protein is heat-labile and pronase-sensitive. Kinetin-binding activity exactly co-chromatographs with a single peak of carbohydrate and protein on gel-filtration and is displaced from concanavalin A-Sepharose 4B by -methylglucoside. On gel filtration, the kinetin-binding protein behaves as a soluble protein with an apparent molecular weight of 180,000 daltons. 相似文献
The effects of parameter dispersion among motor units on the neuromuscular system performance as well as interaction between muscle segments and spinal cord mechanisms are investigated. Elementary components of the system are modeled to simulate with simple models their input-output characteristics. A leaky SS-IPFM encoder with a time-dependent threshold simulates the motor-neuron encoding characteristics. An amplitude and time dependent nonlinear model represent the motor unit mechanical output to neuronal input relationship. The dispersion of parameters in the components of the whole muscle control model is investigated in the open loop mode. It is shown that the dispersion of parameters in the multi-efferent channels converging on a common tendon provides a spatial filtration generating a smoother muscle force in addition to extending the linear dynamic range compared to a similar system having identical motor units. Muscle segmental interaction is investigated in this distributed model by closing the loop through a coupling matrix, representing afferent-motorneuron interaction on the spinal cord level. A diagonal matrix represents no segmental interaction and a uniform matrix represents a uniform interaction between segments through the muscle spindles and Golgi tendon feedback elements. The close loop simulation studied shows that (a). The type of segmental interaction has little effect on the overall system performance, i.e., range of linerity and stability, which is the result of having a muscle system with a large number of motor units. (b) There are only minor differences in results between the uniform and normal parameter distributions tested. (c) A loop gain of 4 divided by 8 in the distributed model can provide linearity through the full physiological force range. (d) Type of segmental interaction has significant effects on the individual segment. A uniform matrix provides a more stable segment due to the spatial filtration resulting from the segmental interaction, while the diagonal noninteracting matrix shows instabilities on the local segmental level despite global stability. The more realistic exponentially decaying spatial interaction matrix yields both global neuromuscular and local segmental stability with the same linear dynamic range generated with the uniform or diagonal matrices. 相似文献
When varanid lizards, Varanus niloticus, were allowed to select their preferred body temperature (c. 34°C) they exhibited swifter growth, larger food intake and superior efficiency of conversion when compared with animals restricted to a maximum body temperature of 24°C. At the higher temperature the animals also exhibited a higher metabolic rate and increased thyroid activity, while those at the lower temperature lostproportionately more energy via respiration. A complete energy budget over a period of 6 weeks is presented. 相似文献
During the course of operating high-rate algae ponds (HRAP) for wastewater treatment and protein production, changes were found in the two main algae species. The observed changes were interpreted to be a reflection of the operation regime and loading combined with environmental conditions. To verify that these changes were phenotypic and not genetic, experiments were conducted on Scenedesmus dimorphus growing in miniponds (110 L) as well as in the laboratory. The results showed that the changes in S. dimorphus were external and due to the changes in the loading and operating conditions of the ponds adjusted to changing environmental conditions. It was found that wastewater treatment efficiency and algal yield are also correlated with the S. dimorphus type. 相似文献
Clonal cell lines possessing parathyroid hormone-stimulated adenylate cyclase were established from a rat osteosarcoma. These lines have retained undiminished hormone responsiveness through more than 5 months in continuous culture. Both the extent stimulation and hormone sensitivity were similar to those found in freshly excised tumor and embryonic bone. 相似文献
This paper explores several data mining and time series analysis methods for predicting the magnitude of the largest seismic event in the next year based on the previously recorded seismic events in the same region. The methods are evaluated on a catalog of 9,042 earthquake events, which took place between 01/01/1983 and 31/12/2010 in the area of Israel and its neighboring countries. The data was obtained from the Geophysical Institute of Israel. Each earthquake record in the catalog is associated with one of 33 seismic regions. The data was cleaned by removing foreshocks and aftershocks. In our study, we have focused on ten most active regions, which account for more than 80% of the total number of earthquakes in the area. The goal is to predict whether the maximum earthquake magnitude in the following year will exceed the median of maximum yearly magnitudes in the same region. Since the analyzed catalog includes only 28 years of complete data, the last five annual records of each region (referring to the years 2006–2010) are kept for testing while using the previous annual records for training. The predictive features are based on the Gutenberg-Richter Ratio as well as on some new seismic indicators based on the moving averages of the number of earthquakes in each area. The new predictive features prove to be much more useful than the indicators traditionally used in the earthquake prediction literature. The most accurate result (AUC = 0.698) is reached by the Multi-Objective Info-Fuzzy Network (M-IFN) algorithm, which takes into account the association between two target variables: the number of earthquakes and the maximum earthquake magnitude during the same year. 相似文献
Two custom-designed bioreactors were used to evaluate the effect of shear on biofilms of a succinic acid producer, Actinobacillus succinogenes. The first bioreactor allowed for in situ removal of small biofilm samples used for microscopic imaging. The second bioreactor allowed for complete removal of all biofilm and was used to analyse biofilm composition and productivity. The smooth, low porosity biofilms obtained under high shear conditions had an average cell viability of 79% compared to 57% at the lowest shear used. The maximum cell-based succinic acid productivity for high shear biofilm was 2.4 g g−1DCW h−1 compared to the 0.8 g g−1DCW h−1 of the low shear biofilm. Furthermore, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays confirmed higher cell metabolic activities for high shear developed biofilm compared to biofilm developed at low shear conditions. Results clearly indicated that high shear biofilm cultivation has beneficial morphological, viability, and cell-based productivity characteristics.
Vascular support structures are important devices for treating valve stenosis. A large population of patients is treated for valvular disease and the preferred mode of treatment is percutaneous valve replacement. Stent devices are proving to be an improved technology in minimally invasive cardiac surgery. This new technology provides highly effective results at minimal cost and with a short duration of hospitalisation. Stents as a supporting structure for tissue valves have evolved over the years into remarkably useful and effective devices. During this process, a number of specific designs have come and gone, and a few have remained. Many design changes were successful, and many were not. This article describes the merits and demerits of various stent designs and details the specific reasons why a particular novel design is expected to be the most suitable implant during and after percutaneous aortic valve replacement. 相似文献