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1.
An investigation on the influence of lead toxicity on some of the hepatic enzymes was studied in rats both after a shorter
interval of 15 d and after longer intervals of 60 and 90 d. Three different doses of lead as 5, 10, and 50 mg/kg body wt were
administered orally on every alternate day. Whereas significant inhibition of succinic dehydrogenase was seen following lead
poisoning, the activity acid and alkaline phosphatase increased with lead intoxication. The histoarchitecture of the liver
was grossly intact. Liver accumulated less lead compared to kidney at 60 and 90 d. 相似文献
2.
Peiyong Guo Ding Lu Jiaying Jiang Liye Zhan Ruoshi Wang 《Chemical Speciation and Bioavailability》2017,29(1):170-178
In this study, the fractionation and distribution of phosphorus (P) in the core sediments of the Shanmei reservoir were investigated by using the chemical extraction method in directions for the first time in order to understand its bio-availability, adsorption characteristics, potential release and environmental significance. The results of the study showed that P in the sediments mainly consisted of inorganic phosphorus (IP) and that IP mainly consisted of non-apatite phosphorus (NAIP). The horizontal and temporal distributions of the P fractions were different from each other, but the vertical distribution was similar, which indicated a trend of stabilization after falling. The content of total phosphorus (TP), IP, organic phosphorus (OP), NAIP, apatite phosphorus (AP), and bio-available phosphorus (BAP) in the sediments during the three seasons ranged from 193.85 to 1664.05 mg·kg?1, 126.90 to 1127.70 mg·kg?1, 43.74 to 669.29 mg·kg?1, 57.62 to 937.07 mg·kg?1, 32.58 to 250.71 mg·kg?1, and 41.06 to 871.82 mg·kg?1, respectively. NAIP contents in the sediments accounted for more than 50% of TP. Using an analysis from three aspects, the eutrophication risk index (ERI) could be used to assess the potential release of P in the sediments, and there was a high release risk of P in the sediments in the Shanmei reservoir. 相似文献
3.
Patterns of mobilization of calcium,magnesium, and phosphorus by embryonic yellow-headed blackbirds(Xanthocephalus xanthocephalus) 总被引:1,自引:0,他引:1
Mary J. Packard Gary C. Packard 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,160(6):649-654
Summary Embryonic blackbirds(Xanthocephalus xanthocephalus) obtain most of their calcium from the eggshell (85 90%), but all of their phosphorus comes from reserves in the yolk (80–85%) and albumen (15–20%). Approximately equal amounts of magnesium are supplied by the eggshell, the yolk, and the albumen. Yolk is depleted of magnesium and phosphorus during embryogenesis, but excess calcium absorbed from the eggeshell is stored in the yolk. Consequently reserves of calcium in the yolk actually increase 8-fold during embryonic development. Our results reveal that altricial birds manifest patterns of mobilization and deposition of calcium and other elements similar to those described for precocial species. Evolution of altriciality from precocity evidently did not entail major changes in how embryonic birds meet the challenge of obtaining the calcium, magnesium, and phosphorus required for development. 相似文献
4.
Photosynthetic characteristics, specific leaf mass, chlorophyll and total leaf nitrogen concentrations of four herbaceous
plants (Dicranopteris linearis, Hanguana malayana, Pentaphragma ellipticum, Tacca integrifolia) from nutrient-poor tropical
forests showed that all these plants were well-adapted to their natural growth environments. No photoinhibition was observed
even in the understorey plants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
《Cryobiology》2016,72(3):419-431
Cryoprotection of bulky organs is crucial for their storage and for subsequent transplantation. In this work we demonstrate the capability of the X-ray computed tomography (CT) as a non-invasive method to measure the cryoprotectant (cpa) concentration inside a tissue or an organ, specifically for the case of dymethil sulfoxide (Me2SO). It is remarkable that the use of Me2SO has been leader in techniques of cells and tissues cryopreservation. Although CT technologies are mainly based in density differences, and many cpas are alcohols with densities similar to water, the use of very low energies as acceleration voltage (∼70 kV) and the sulfur atom in the molecule of Me2SO makes possible the visualization of this cpa inside tissues. As result we obtain a CT signal proportional to the Me2SO concentration with a spatial resolution up to 50 μm in the case of our device. 相似文献
6.
《Bioorganic & medicinal chemistry》2020,28(4):115310
Increasing structural options in medicinal chemistry is important for the development of novel and distinctive drug candidates. In this study, we focused on phosphorus-containing functionalities. We designed and synthesized a series of phosphinophenol derivatives and determined their physicochemical properties, including hydrophobicity parameter LogP, and their biological activity toward estrogen receptor (ER). Notably, the phosphine borane derivatives (9 and 14) exhibited potent ER-antagonistic activity, exceeding the potency of the corresponding alkane (15) and silane (16) derivatives, despite having a less hydrophobic nature. The determined physicochemical parameters will be helpful for the rational design of phosphorus-containing biologically active compounds. Our results indicate that phosphine boranes are a promising new chemical entry in the range of structural options for drug discovery. 相似文献
7.
《Animal : an international journal of animal bioscience》2019,13(1):119-126
Rib bone biopsy samples are often used to estimate changes in skeletal mineral reserves in cattle but differences in sampling procedures and the bone measurements reported often make interpretation and comparisons among experiments difficult. ‘Full-core’ rib bone biopsy samples, which included the external cortical bone, internal cortical bone and trabecular bone (CBext, CBint and Trab, respectively), were obtained from cattle known to be in phosphorus (P) adequate (Padeq) or severely P-deficient (Pdefic) status. Experiments 1 and 2 examined growing steers and Experiment 3 mature breeder cows. The thickness of cortical bone, specific gravity (SG), and the amount and concentration of ash and P per unit fresh bone volume, differed among CBext, CBint and Trab bone. P concentration (mg/cc) was closely correlated with both SG and ash concentrations (pooled data, r=0.99). Thickness of external cortical bone (CBText) was correlated with full-core P concentration (FC-Pconc) (pooled data, r=0.87). However, an index, the amount of P in CBext per unit surface area of CBext (PSACB; mg P/mm2), was more closely correlated with the FC-Pconc (pooled data, FC-Pconc=37.0+146×PSACB; n=42, r=0.94, RSD=7.7). Results for measured or estimated FC-Pconc in 10 published studies with cattle in various physiological states and expected to be Padeq or in various degrees of Pdefic status were collated and the ranges of FC-Pconc indicative of P adequacy and P deficiency for various classes of cattle were evaluated. FC-Pconc was generally in the range 130 to 170 and 100 to 120 mg/cc fresh bone in Padeq mature cows and young growing cattle, respectively. In conclusion, the FC-Pconc could be estimated accurately from biopsy samples of CBext. This allows comparisons between studies where full-core or only CBext biopsy samples of rib bone have been obtained to estimate changes in the skeletal P status of cattle and facilitates evaluation of the P status of cattle. 相似文献
8.
Liver plasma membranes prepared from genetically diabetic (db/db) mice expressed levels of Gi α-2, Gi α-3 and G-protein β-subunits that were reduced by some 75, 63 and 73% compared with levels seen in membranes from lean animals. In contrast, there were no significant differences in the expression of the 42 and 45 kDa forms of Gs α-subunits. Pertussis toxin-catalysed ADP-ribosylation of membranes from lean animals identified a single 41 kDa band whose labelling was reduced by some 86% in membranes from diabetic animals. Cholera toxin-catalysed ADP-ribosylation identified two forms of Gs α-subunits whose labelling was about 4-fold greater in membranes from diabetic animals compared with those from lean animals. Maximal stimulations of adenylyl cyclase activity by forskolin (100 μM), GTP (100 μM), p[NH]ppG (100 μM), NaF (10 mM) and glucagon (10 μM) were similar in membranes from lean and diabetic animals, whereas stimulation by isoprenaline (100 μM) was lower by about 22%. Lower concentrations (EC50-60 nM) of p[NH]ppG were needed to activate adenylyl cyclase in membranes from diabetic animals compared to those from lean animals (EC50-158 nM). As well as causing activation, p[NH]ppG was capable of eliciting a pertussis toxin-sensitive inhibitory effect upon forskolin-stimulated adenylyl cyclase activity in membranes from both lean and diabetic animals. However, maximal inhibition of adenylyl cyclase activity in membranes from diabetic animals was reduced to around 60% of that found using membranes from lean animals. Pertussis toxin-treatment in vivo enhanced maximal stimulation of adenylyl cyclase by glucagon, isoprenaline and p[NH]ppG through a process suggested to be mediated by the abolition of functional Gi activity. The lower levels of expression of G-protein β-subunits, in membranes from diabetic compared with lean animals, is suggested to perturb the equilibria between holomeric and dissociated G-protein subunits. We suggest that this may explain both the enhanced sensitivity of adenylyl cyclase to stimulation by p[NH]ppG in membranes from diabetic animals and the altered ability of pertussis and cholera toxins to catalyse the ADP-ribosylation of G-proteins in membranes from these two animals. 相似文献
9.
10.
大气CO2浓度升高影响植物光合作用过程和生物量积累,改变植物地上和地下生物量的动态分配.土壤有机质的形成和周转依赖于植物组分的输入,因此,CO2浓度升高所造成的植物生理和代谢的变化对土壤碳库收支平衡具有重要影响.采用稳定碳同位素(13C)技术研究土壤-植物系统的碳循环可阐明大气CO2浓度升高条件下光合碳在植物各器官的分配特征和时间动态,明确光合碳在土壤中的积累、分解与迁移转化过程以及对土壤有机碳库周转的影响.本文综述了基于13C自然丰度法或13C示踪技术研究大气CO2浓度升高对土壤-植物系统碳循环的影响,主要包括:1)对植物光合作用的同位素分馏的影响;2)对植物光合碳(新碳)分配动态的影响;3)对土壤有机碳新老碳库动态以及微生物转化过程的影响.明确上述过程及其调控机制可为预测CO2浓度升高对陆地生态系统碳循环及源汇效应的长期影响奠定基础. 相似文献