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1.
Scavenging of superoxide radical by ascorbic acid 总被引:1,自引:0,他引:1
Using acetaldehyde and xanthine oxidase as the source of suPeroxide radical, the second order rate constant for the reaction
between ascorbic acid and superoxide radical was estimated to be 8.2 X 107 M-1 s-1. In rats, the average tissue concentration of ascorbic acid was of the order of 10-3 M and that of superoxide dismutase was of the order of 10-6 M. So, taking together both the rate constants and the tissue concentrations, the efficacy of ascorbic acid for scavenging
superoxide radical in animal tissues appears to be better than that of suPeroxide dismutase. The significance of ascorbic
acid as a scavenger of superoxide radical has been discussed from the point of view of the evolution of ascorbic acid synthesizing
capacity of terrestrial vertebrates. 相似文献
2.
The large family of signal transducing proteins known as G proteins are heterotrimers that dissociate into an independent α-subunit and βγ-subunit complex after ligand binding or other stimulation. For Gα, at least 30 distinct sequences representing 10 different classes have been identified. On the other hand, cDNAs for only three Gβ-subunit genes have been isolated so far. All three of the Gβ genes have been chromosomally mapped in the human, but only two in the mouse. Using a human retinal cDNA for the third G protein β-subunit, we have mapped the corresponding gene, termed Gnb-3, to mouse Chromosome 6 with somatic cell hybrids and have positioned it distal to but near the marker Raf-1 by analysis of the progeny of three genetic crosses. 相似文献
3.
Summary In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA3) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA3, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA3 the floral buds developed into flowers only in decapitated plants. 相似文献
4.
Sajal Chakraborti Sandip K. Batabyal John R. Michael Tapati Sanyal 《Molecular and cellular biochemistry》1994,130(2):121-127
Exposure of rabbit pulmonary arterial smooth muscle cells to 10 M of the calcium ionophore A23187 dramatically stimulates cell membrane-associated phospholipase A2 activity and arachidonic acid release. In addition, A23187 also enhances cell membrane-associated serine esterase activity. Serine esterase inhibitors phenylmethylsulfonylfuoride and diisopropyl fluorophosphate prevent the increase in serine esterase and phospholipase A2 activities and arachidonic acid release caused by A23187. A23187 still stimulated serine esterase and phospholipase A2 activities and arachidonic acid release in cells pretreated with nominal Ca2+ free buffer. Treatment of the cell membrane with A23187 does not cause any appreciable change in serine esterase and phospholipase A2 activities. Pretreatment of the cells with actinomycin D or cycloheximide did not prevent the increase in the cell membrane associated serine esterase and phospholipase A2 activities, and arachidonic acid release caused by A23187. These results suggest that (i) a membrane-associated serine esterase plays an important role in stimulating the smooth muscle cell membrane associated phospholipase A2 activity (ii) in addition to the presence of extracellular Ca2+, release of Ca2+ from intracellular storage site(s) by A23187 also appears to play a role in stimulating the cell membrane-associated serine esterase and phospholipase A2 activities, and (iii) the increase in the cell membrane-associated serine esterase and phospholipase A2 activities does not appear to require new RNA or protein synthesis.Abbreviations A23187
calcium ionophore
- AA
arachidonic acid
- PMSF
phenylmethyl sulfonylfuoride
- DFP
diisopropyl-fluorophosphate
- DMEM
Dulbecco's modified Eagles medium
- FCS
fetal calf serum
- PBS
phosphate buffered saline
- HBPS
Hank's buffered physiological saline
- PLA2
phospholipase A2 相似文献
5.
Alterations of Phospholipid Metabolism in Rat Cerebral Cortex Mince Induced by Cationic Amphiphilic Drugs 总被引:3,自引:3,他引:0
Abstract Cationic amphiphilic drugs (CADs) of varied clinical use were screened to determine their capacity to alter the pattern of labeling with 32 Pj of cerebral cortex mince phospholipids. The altered phospholipid labeling patterns were qualitatively similar, the prominent features being reduced incorporation into phosphatidylcholine and increased incorporation into phosphatidic acid. Relative potencies were: (±)-propranolol > chlorpromazine = 4,4'-bis(diethylaminoethoxy) α,β -diethyldiphenylethane > desipramine > di-bucaine > pimozide > oxymetazoline = fenfluramine = haloperidol = chloroquine > amphetamine = no drug added. Propranolol was used to study the action of CADs further. Its effect was time- and dose-dependent, but in contrast with pineal gland, no label appeared in phosphatidyl-CMP (CDP-diacylglycerol), nor did dialysis of the mince to reduce diffusible substrates or exogenous addition of substrates cause appearance of liponucleotide. Thus lack of diffusible precursors is not responsible for CAD effects in vitro. Pulse-chase experiments with 32 P1 and [2-3 H]glycerol suggested that inhibition of phosphatidate phosphohydrolase may be partly responsible for the observed alterations in phospholipid labeling in the presence of CADs. 相似文献
6.
Saravanan Munisankar Anuradha Rajamanickam Suganthi Balasubramanian Satishwaran Muthusamy Chandra Kumar Dolla Pradeep Aravindan Menon Ponnuraja Chinnayan Christopher Whalen Paschaline Gumne Inderdeep Kaur Varma Nadimpalli Akshay Deverakonda Zhenhao Chen John David Otto Tesfalidet Habitegiyorgis Harish Kandaswamy Thomas B. Nutman Subash Babu 《PLoS neglected tropical diseases》2022,16(7)
BackgroundThe prevalence of Strongyloides stercoralis infection is estimated to be 30–100 million worldwide, although this an underestimate. Most cases remain undiagnosed due to the asymptomatic nature of the infection. We wanted to estimate the seroprevalence of S. stercoralis infection in a South Indian adult population.MethodsTo this end, we performed community-based screening of 2351 individuals (aged 18–65) in Kanchipuram District of Tamil Nadu between 2013 and 2020. Serological testing for S. stercoralis was performed using the NIE ELISA.ResultsOur data shows a seroprevalence of 33% (768/2351) for S. stercoralis infection which had a higher prevalence among males 36% (386/1069) than among females 29.8% (382/1282). Adults aged ≥55 (aOR = 1.65, 95% CI: 1.25–2.18) showed higher adjusted odds of association compared with other age groups. Eosinophil levels (39%) (aOR = 1.43, 95% CI: 1.19–1.74) and hemoglobin levels (24%) (aOR = 1.25, 95% CI: 1.11–1.53) were significantly associated with S. stercoralis infection. In contrast, low BMI (aOR = 1.15, 95% CI: 0.82–1.61) or the presence of diabetes mellitus (OR = 1.18, 95% CI: 0.83–1.69) was not associated with S. stercoralis seropositivity.ConclusionsOur study provides evidence for a very high baseline prevalence of S. stercoralis infection in South Indian communities and this information could provide realistic and concrete planning of control measures. 相似文献
7.
Type IA DNA topoisomerases, typically found in bacteria, are essential enzymes that catalyse the DNA relaxation of negative supercoils. DNA gyrase is the only type II topoisomerase that can carry out the opposite reaction (i.e. the introduction of the DNA supercoils). A number of diverse molecules target DNA gyrase. However, inhibitors that arrest the activity of bacterial topoisomerase I at low concentrations remain to be identified. Towards this end, as a proof of principle, monoclonal antibodies that inhibit Mycobacterium smegmatis topoisomerase I have been characterized and the specific inhibition of Mycobacterium smegmatis topoisomerase I by a monoclonal antibody, 2F3G4, at a nanomolar concentration is described. The enzyme-bound monoclonal antibody stimulated the first transesterification reaction leading to enhanced DNA cleavage, without significantly altering the religation activity of the enzyme. The stimulated DNA cleavage resulted in perturbation of the cleavage-religation equilibrium, increasing single-strand nicks and protein-DNA covalent adducts. Monoclonal antibodies with such a mechanism of inhibition can serve as invaluable tools for probing the structure and mechanism of the enzyme, as well as in the design of novel inhibitors that arrest enzyme activity. 相似文献
8.
Ge X McFarlane C Vajjala A Lokireddy S Ng ZH Tan CK Tan NS Wahli W Sharma M Kambadur R 《Cell research》2011,21(11):1591-1604
TGF-β and myostatin are the two most important regulators of muscle growth. Both growth factors have been shown to signal through a Smad3-dependent pathway. However to date, the role of Smad3 in muscle growth and differentiation is not investigated. Here, we demonstrate that Smad3-null mice have decreased muscle mass and pronounced skeletal muscle atrophy. Consistent with this, we also find increased protein ubiquitination and elevated levels of the ubiquitin E3 ligase MuRF1 in muscle tissue isolated from Smad3-null mice. Loss of Smad3 also led to defective satellite cell (SC) functionality. Smad3-null SCs showed reduced propensity for self-renewal, which may lead to a progressive loss of SC number. Indeed, decreased SC number was observed in skeletal muscle from Smad3-null mice showing signs of severe muscle wasting. Further in vitro analysis of primary myoblast cultures identified that Smad3-null myoblasts exhibit impaired proliferation, differentiation and fusion, resulting in the formation of atrophied myotubes. A search for the molecular mechanism revealed that loss of Smad3 results in increased myostatin expression in Smad3-null muscle and myoblasts. Given that myostatin is a negative regulator, we hypothesize that increased myostatin levels are responsible for the atrophic phenotype in Smad3-null mice. Consistent with this theory, inactivation of myostatin in Smad3-null mice rescues the muscle atrophy phenotype. 相似文献
9.