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排序方式: 共有256条查询结果,搜索用时 218 毫秒
1.
2.
Vijay Pal Singh Rangoli Aggarwal Suchita Singh Arpita Banik Tanveer Ahmad Bijay Ranjan Patnaik Giridharan Nappanveettil Kunal Pratap Singh Madan Lal Aggarwal Balaram Ghosh Anurag Agrawal 《PloS one》2015,10(6)
Epidemiological studies have shown an increased obesity-related risk of asthma. In support, obese mice develop airway hyperresponsiveness (AHR). However, it remains unclear whether the increased risk is a consequence of obesity, adipogenic diet, or the metabolic syndrome (MetS). Altered L-arginine and nitric oxide (NO) metabolism is a common feature between asthma and metabolic syndrome that appears independent of body mass. Increased asthma risk resulting from such metabolic changes would have important consequences in global health. Since high-sugar diets can induce MetS, without necessarily causing obesity, studies of their effect on arginine/NO metabolism and airway function could clarify this aspect. We investigated whether normal-weight mice with MetS, due to high-fructose diet, had dysfunctional arginine/NO metabolism and features of asthma. Mice were fed chow-diet, high-fat-diet, or high-fructose-diet for 18 weeks. Only the high-fat-diet group developed obesity or adiposity. Hyperinsulinemia, hyperglycaemia, and hyperlipidaemia were common to both high-fat-diet and high-fructose-diet groups and the high-fructose-diet group additionally developed hypertension. At 18 weeks, airway hyperresponsiveness (AHR) could be seen in obese high-fat-diet mice as well as non-obese high-fructose-diet mice, when compared to standard chow-diet mice. No inflammatory cell infiltrate or goblet cell metaplasia was seen in either high-fat-diet or high-fructose-diet mice. Exhaled NO was reduced in both these groups. This reduction in exhaled NO correlated with reduced arginine bioavailability in lungs. In summary, mice with normal weight but metabolic obesity show reduced arginine bioavailability, reduced NO production, and asthma-like features. Reduced NO related bronchodilation and increased oxo-nitrosative stress may contribute to the pathogenesis. 相似文献
3.
Indirect evidence suggests that legumes can adjust rapidly theresistance of their root nodules to O2 diffusion. Here we describeexperiments using O2 specific micro-electrodes and dark fieldmicroscopy to study directly the operation of this diffusionbarrier. The O2 concentration sensed by the electrode decreasedsharply in the region of the inner cortex and was less than1.0 mmol m3 throughout the infected tissue in nodulesof both pea (Pisum sativum) and french bean (Phaseolus vulgaris).In a number of experiments the ambient O2 concentration wasincreased to 40% while the electrode tip was just inside theinner cortex. In 13 out of 21 cases the O2 concentration atthis position either remained low and unchanged or increasedirreversibly to near ambient values. In the remaining casesthe O2 concentration increased after 1 to 2.5 min and then decreasedto its former value. These results are ascribed to an increasein resistance of the barrier in response to increased O2 fluxinto the nodule. It was shown microscopically that air spacesboth at the boundary between the infected zone and the innercortex, and within the infected zone started to disappear 3min after nodules were exposed to high ambient O2 concentrationsand had disappeared completely after 8 min. These spaces werenot changed by exposure of the nodule for 10 min to either N2or air. Key words: Oxygen, root nodules, air spaces 相似文献
4.
Evolution of the 28S ribosomal RNA gene in anurans: regions of variability and their phylogenetic implications 总被引:1,自引:0,他引:1
Fifteen restriction sites were mapped to the 28S ribosomal RNA gene of
individuals representing 54 species of frogs, two species of salamanders, a
caecilian, and a lungfish. Eight of these sites were present in all species
examined, and two were found in all but one species. Alignment of these
conserved restriction sites revealed, among anuran 28S rRNA genes, five
regions of major length variation that correspond to four of 12 previously
identified divergent domains of this gene. One of the divergent domains
(DD8) consists of two regions of length variation separated by a short
segment that is conserved at least throughout tetrapods. Most of the
insertions, deletions, and restriction-site variations identified in the
28S gene will require sequence-level analysis for a detailed reconstruction
of their history. However, an insertion in DD9 that is coextensive with
frogs in the suborder Neobatrachia, a BstEII site that is limited to
representatives of two leptodactylid subfamilies, and a deletion in DD10
that is found only in three ranoid genera are probably synapomorphies.
相似文献
5.
Calcium-Stimulated Proteolysis in Myelin: Evidence for a Ca2+ -Activated Neutral Proteinase Associated with Purified Myelin of Rat CNS 总被引:1,自引:1,他引:0
Incubation of myelin purified from rat spinal cord with CaCl2 (1-5 mM) in 10-50 mM Tris-HCl buffer at pH 7.6 containing 2 mM dithiothreitol resulted in the loss of both the large and small myelin basic proteins (MBPs), whereas incubation of myelin with Triton X-100 (0.25-0.5%) and 5 mM EGTA in the absence of calcium produced preferential extensive loss of proteolipid protein (PLP) relative to MBP. Inclusion of CaCl2 but not EGTA in the medium containing Triton X-100 enhanced degradation of both PLP and MBPs. The Ca2+-activated neutral proteinase (CANP) activity is inhibited by EGTA (5 mM) and partially inhibited by leupeptin and/or E-64c. CANP is active at pH 5.5-9.0, with the optimum at 7-8. The threshold of Ca2+ activation is approximately 100 microM. The 150K neurofilament protein (NFP) was progressively degraded when incubated with purified myelin in the presence of Ca2+. These results indicate that purified myelin is associated with and/or contains a CANP whose substrates include MBP, PLP, and 150K NFP. The degradation of PLP (trypsin-resistant) in the presence of detergent suggests either release of enzyme from membrane and/or structural alteration in the protein molecule rendering it accessible to proteolysis. The myelin-associated CANP may be important not only in the turnover of myelin proteins but also in myelin breakdown in brain diseases. 相似文献
6.
Walter W. McAlhaney Naren L. Banik Seymour Greenfield Edward L. Hogan 《Neurochemical research》1986,11(2):173-183
Six proteolytic enzymes were assayed for activity in quaking CNS in examining the hypothesis that increased proteolytic activity contributes to the hypomyelination characteristic of this mutant. Cathepsin B-like enzyme, cathepsin D, neutral proteinase, calcium-activated neutral proteinase, prolyl endopeptidase, and diaminopeptidase II were assayed in whole homogenate of brain or spinal cord and each was found to have activity similar to that in normal mice. These results do not support a relationship between proteolysis and the genetic defect and suggest that other factors should be investigated to delineate the pathogenesis of this mutant. 相似文献
7.
Foreign protein expression from the commonly used SV40 promoter has been found to be primarily during the S-phase of the cell cycle. Simple mathematical models with this cell cycle phase dependent expression of foreign protein suggest that the specific production rate will be proportional to the cell growth rate, which is particularly disadvantageous in high cell density fed-batch or perfusion bioreactors. In this study we investigate this predicted relationship between the production rate and growth rate by culturing recombinant CHO cells in a continuous suspension bioreactor. One CHO cell line, GS-26, has been stably transfected with the plasmid pSVgal, which contains the E. coli lac Z gene under the control of the SV40 promoter. This GS-26 cell line was grown in suspension cultures over a range of specific growth rates in batch and continuous modes. The intracellular -galactosidase activity was assayed using a standard spectrophotometric method after breaking the cells open and releasing the enzyme. A strong growth associated relationship is found between the intracellular -galactosidase content and the specific growth rate in batch and continuous cultures, as predicted. 相似文献
8.
In this work, metabolite and antibody production kinetics of hybridoma cultures were investigated as a function of cell density and growth rate in a homogeneous perfusion reactor. Hydrophilized hollow fiber polypropylene membranes with a pore size of 0.2 m were used for medium perfusion. Oxygen was supplied to the cells through thin walled silicone tubing. The mouse-mouse hybridoma cells were grown in three identical bioreactors at perfusion rates of 1.1, 2.0, and 3.2/day for a period of eight days during which the viable cell concentrations reached stable values of 2.6×106, 3.5×106, and 5.2×106 cells/ml, respectively. Total cell densities reached values ranging from 8×106 to 1×106 cells/ml. Specific substrate consumption and product formation rates responded differently to changes in cell density and apparent specific growth rate, which were not varied independently. Using multiple regression analysis, the specific glucose consumption rate was found to vary with viable cell density while the specific glutamine uptake and lactate production rates varied with both viable cell density and apparent specific growth rate. These results suggest that cell density dictates the rate of glucose consumption while the cell growth rate influences how glucose is metabolized, i.e., through glycolysis or the TCA cycle. The specific antibody production rate was found to be a strong function of cell density, increasing as cell density increased, but was essentially independent of the specific growth rate for the cell line under study.List of Symbols MAb
monoclonal antibody
-
X
v
viable cell density (cells/ml)
-
X
d
nonviable cell density (cells/ml)
-
specific growth rate (1/day)
-
k
d
specific death rate (1/day)
-
D
dilution rate (1/day)
-
S
f
substrate concentration in feed (g/l or mM)
-
S
substrate concentration (g/l or mM)
-
P
f
product concentration in feed (g/l or g/ml)
-
P
product concentration (g/l or ug/ml)
-
q
s
specific consumption rate of substrate (g/hr/cell or mmol/hr/cell)
-
q
p
specific production rate of product (g/hr/cell)
-
q
MAb
specific production rate of monoclonal antibody (g/hr/cell)
This work was supported in part by a grant for the National Science Foundation (BCS-9157851) and by matching funds from Merck and Monsanto. We sincerely thank Mr. Roland Buchele of Akzo Inc. (Germany) for donation of the polypropylene membranes, Dr. Michael Fanger (Dartmouth Medical School) for the hybridoma cell line, Dr. Sadettin Ozturk (Verax Corp., Lebanon, NH) for technical discussions regarding reactor design, and Dr. Derrick Rollins (Iowa State University) for advice on statistical methods. 相似文献
9.
Rajendra V. Deshpande Jean-Michel Goust Naren L. Banik Ph.D. 《Neurochemical research》1993,18(7):767-773
Calpain, a calcium-activated neutral proteinase, is ubiquitously present in human tissues. To determine if lymphoid cells implicated in pathogenesis of demyelination may harbor calpain in a functionally active form, we determined both Calpain and mCalpain activities in human lymphoid cell lines. DEAE-cellulose and phenylsepharose column chromatography were used to isolate the enzyme from the natural inhibitor, calpastatin. Lymphocytic lines (CCRF-CEM, MOLT-3, MOLT-4, M.R.) showed predominance of Calpain (55–80%) whereas the monocytic line (U-937) showed prodominance of mCalpain (77%). Proportion and subcellular distribution of both isoforms varied among cell lines. Calpains isolated from U-937 cells degraded myelin basic protein. These results indicate that human lymphoid cells harbor functionally active calpain that can degrade myelin components in vitro. The study suggests a degradative role for calpain in demyelinating diseases. 相似文献
10.
A. K. Banik 《Folia microbiologica》1976,21(2):139-143
The mineral requirements of a strain ofAspergillus niger for the production of citric acid in a synthetic medium were studied. It was observed that K2HPO4 and MgSO4.7 H2O were required at concentrations of 0.1% and 0.02% respectively. The optimum level of each of the trace elements Fe, Mn and
Zn was 1.0 μg/ml. NaCl and CaCl2 at lower concentrations had no effect on citric acid production. Trace elements, Cu, Co and Mo, had an adverse effect on
the production of citric acid while Ni and V were without effect. 相似文献