Mechanistic insights into the allosteric inactivation mechanism of ZAP-70 induced by the hot spot W165C mutation

Zeta chain-associated protein kinase 70 (ZAP-70) is a non-receptor tyrosine kinase that interacts with the activated T-cell receptor to transduce downstream signals, and thus plays an important role in the adaptive immune system. The biphosphorylated immunotyrosine-based activation motifs (ITAM-Y2P) binds to the N-SH2 and C-SH2 domains of ZAP-70 to promote the activation of ZAP-70. The present study explores molecular mechanisms of allosteric inactivation of ZAP-70 induced by the hot spot W165C mutation through atomically detailed molecular dynamics simulation approaches. We report microsecond-length simulations of two states of the tandem SH2 domains of ZAP-70 in complex with the ITAM-Y2P motif, including the wild-type and W165C mutant. Extensive analysis of local flexibility and dynamical correlated motions show that W165C mutation changes coupled motions of protein domains and community networks. The binding affinities of the ITAM-Y2P motif to the wild-type and W165C mutant of ZAP-70 are predicted using binding free energy calculations. The results suggest that the driving force to decrease the binding affinity in the W165C mutant derives from the difference in the protein-protein electrostatic interactions. Moreover, the per-residue free energy decomposition unravels that the contributions from residues in the phosphorylated Tyr315 (pY315) binding site, in particular pY315 of ITAM-Y2P, and Arg43, Tyr240 of ZAP-70, are the key determinants for the loss of binding affinity. This study may insights into our understanding of the pathological mechanism of ZAP-70.Communicated by Ramaswamy H. Sarma.

[Therapeutic effect of combined use of FGF1-loaded nano-liposomes and ultrasound-targeted microbubble destruction technique on treating rats with experimental diabetic cardiomyopathy]

Objective: The therapeutic effect of acid fibroblast growth factor 1(FGF1) on rats with diabetic cardiomyopathy (DCM) was evaluated by using nano-liposomes combined with ultrasound-targeted microbubble destruction technique (UTMD). Methods: The FGF1-loaded nano-liposomes were prepared by water-in-water emulsion method combined with lyophilization technique.TypeⅠdiabetes model was induced by intraperitoneal injection of streptozotocin (STZ, 70 mg/kg) in 60 male SD rats.Sixteen weeks later, diabetic rats were randomly divided into: placebo group (saline treatment), FGF1 group, FGF1-loaded nano-liposomes group, and FGF1-loaded nano-liposomes plus UTMD group (n=15 each). After two weeks of intervention followed by 2 weeks intervention stop, all rats underwent cardiac catheterization, and the left ventricular end-systolic pressure (LVESP), left ventricular end-diastolic pressure (LVEDP) and the maximal increase/decrease rate of left ventricular pressure (LV±dp/dtmax) were measured.Then, the rats were sacrificed and myocardial tissue were obtained for Masson trichrome staining, TUNEL apoptotic staining and CD31 immunohistochemistry staining to quantify myocardial collagen fraction (CVF), cardiac myocyte apoptotic index and myocardial microvascular density (MVD). Results: (1)Scanning electron microscope results revealed good morphology and FGF1 encapsulation efficiency (84.3±2.8)% with high stability and dispensability of FGF1 loaded nano-liposomes.(2)The hemodynamic evaluation showed that LVESP, LV + dp/dt(max) and LV -dp/dt(max) were all significantly higher, while LVEDP was significantly lower in the FGF1-loaded nano-liposome+ UTMD group than in DCM group, FGF1 solution group, and FGF1 nano-liposome group(all P<0.05). (3)The Masson trichrome staining demonstrated that CVF was significantly higher in all DCM groups than in control group and was significantly lower in the FGF1-loaded nano-liposome+ UTMD group than in DCM group, FGF1 solution group, and FGF1 nano-liposome group (all P<0.05). (4)The CD31 immunohistochemical staining results showed that MVD was significantly lower in all DCM groups than in control group and was significantly higher in the FGF1-loaded nano-liposome+ UTMD group than in DCM group, FGF1 solution group, and FGF1 nano-liposome group (all P<0.05). (5)The TUNEL results showed that apoptotic index was significantly higher in all DCM groups than in control group and was significantly lower in the FGF1-loaded nano-liposome + UTMD group than in DCM group, FGF1 solution group, and FGF1 nano-liposome group (all P<0.05). Conclusion: FGF1 nano-liposomes combining with UTMD technique can significantly improve cardiac functions and attenuate myocardial CVF and apoptosis and enhance myocardial MVD in DCM rats.

Safety distance assessment of industrial toxic releases based on frequency and consequence: a case study in Shanghai, China

A case study on the safety distance assessment of a chemical industry park in Shanghai, China, is presented in this paper. Toxic releases were taken into consideration. A safety criterion based on frequency and consequence of major hazard accidents was set up for consequence analysis. The exposure limits for the accidents with the frequency of more than 10(-4), 10(-5)-10(-4) and 10(-6)-10(-5) per year were mortalities of 1% (or SLOT), 50% (SLOD) and 75% (twice of SLOD) respectively. Accidents with the frequency of less than 10(-6) per year were considered incredible and ignored in the consequence analysis. Taking the safety distance of all the hazard installations in a chemical plant into consideration, the results based on the new criterion were almost smaller than those based on LC50 or SLOD. The combination of the consequence and risk based results indicated that the hazard installations in two of the chemical plants may be dangerous to the protection targets and measurements had to be taken to reduce the risk. The case study showed that taking account of the frequency of occurrence in the consequence analysis would give more feasible safety distances for major hazard accidents and the results were more comparable to those calculated by risk assessment.

Heavy metal concentrations in soil and earthworms in a floodplain grassland

We determined accumulated heavy metal concentrations (Cd, Pb, Cu, Zn) of earthworms in moderately contaminated floodplain soils. Both soil and mature earthworms were sampled before and after flooding and earthworm species were identified to understand species specific differences in bioconcentration. Accumulated metal concentrations in floodplain earthworms differed before and after flooding. Differences in uptake and elimination mechanisms, in food choice and living habitat of the different earthworm species and changes in speciation of the heavy metals are possible causes for this observation. Regression equations taken from literature, that relate metal accumulation by earthworms in floodplains as a function of metal concentration in soil, performed well when all species specific data were combined in an average accumulation, but did not address differences in accumulation between earthworm species.

Evidence for second-phonon nuclear wobbling

The nucleus 163Lu has been populated through the reaction 139La(29Si,5n) with a beam energy of 157 MeV. Three triaxial, strongly deformed (TSD) bands have been observed with very similar rotational properties. The first excited TSD band has earlier been assigned as a one-phonon wobbling excitation built on the lowest-lying (yrast) TSD band. The large B(E2)(out)/B(E2)(in) value obtainable for one of four observed transitions between the second and first excited TSD bands is in good agreement with particle-rotor calculations for a two-phonon wobbling excitation.

Effect of beringite on cadmium and zinc uptake by plants and earthworms: more than a liming effect?

Metal-contaminated soils are potentially harmful to plants, animals, and humans. Harmful effects are often related to the free-metal concentration in the soil solution. Immobilization is a potentially useful method to improve the quality of metal-contaminated soils by transforming free-metal ions into species that are less mobile and less toxic. The effect of many immobilizing products can be attributed to sorption on the surface of the material. Alkaline materials also enhance adsorption to soil particles by decreasing proton competition. Immobilization should preferably be evaluated independently of soil pH to discriminate between these processes. In this study, the immobilizing effect of beringite, an alkaline alumino silicate, was compared with that of lime. Plants (Swiss chard [Beta vulgaris L. var. cicla]) were grown on a soil contaminated with cadmium and zinc and treated with graded amounts of beringite or lime. Metal availability, as determined by a 0.01 M CaCl2 extraction, and metal uptake by plants strongly decreased in all treated soils. Beringite did not reduce metal availability more than liming when the obtained pH levels were similar. The effect of beringite can, therefore, be explained as a liming effect, at least for the duration of our experiment (10 weeks). The effect of beringite and lime on metal accumulation by earthworms (Eisenia veneta and Lumbricus rubellus) was small or not significant, although the CaCl2-extractable metal concentration in treated soils decreased by more than 90%. We conclude that immobilizing agents based on a liming effect can decrease metal uptake by plants, but they will hardly affect metal uptake by earthworms. Hence, these materials can reduce negative ecological effects of metal contamination on plants and herbivores, but not on earthworm predators.

Phase transitions above the Yrast line in 154Dy

Spectra of the E2 quasicontinuum gamma rays feeding different spin regions of the 154Dy yrast line have been extracted. These are compared with corresponding theoretical spectra obtained by numerical simulations based on temperature-dependent Hartree-Fock theory, with thermal shape fluctuations. In this manner, different regions of the spin-energy plane can be examined. The results support the predictions of a smeared-out phase transition at high spin above the yrast line.

Spatial and temporal trends in levels of trace metals and PCBs in the European badger Meles meles (L., 1758) in The Netherlands: implications for reproduction

In The Netherlands the European badger Meles meles is presently recovering from earlier declines in numbers. The rate of recovery, however, varies between regions. It is argued that the effects of traffic accidents cannot account for the differences in recovery between regions. It is further shown that the population recovery is relatively poor in areas with high cadmium and zinc concentrations, such as near rivers. It is suggested that cadmium has an adverse effect on reproduction and that this effect is amplified by the social structure of the badger family. While traffic has a severe impact on the total population, trace metals may affect populations locally. Contrary to cadmium and zinc, lead and copper concentrations are decreasing with time. PCBs are generally not above critical levels, although there are some local exceptions, which may be related to fluctuations in physiological condition of individual badgers.

Inhibition of protein synthesis by reduced K+ in cultured endothelial cells

Total protein synthesis (as precipitable [3H] leucine incorporation) was determined under various experimental conditions to examine the relationship between cellular K+ and protein synthesis in human umbilical vein endothelial cells (HUVEC). We found that under normal external K+ concentration (5 mM), total protein synthesis was inhibited by cycloheximide and ouabain, with estimated values of IC50 of 0.41 microM and 0.60 mM, respectively. Cellular K+ concentrations were determined (102 +/- 4 mM for control cells) and found to be significantly increased (P < 0.01) by high external K+ (25 mM) and significantly decreased (P < 0.001) by low external K+ (0.5 mM) as well as by ouabain (2 mM). Under high external K+, total protein synthesis and the inhibitory responses of cycloheximide and ouabain were not altered. On the contrary, cellular K+ and protein synthesis were both further reduced by about half (P < 0.001) under low external K+. While ouabain further reduced cellular K+ by half (P < 0.001), protein synthesis was only slightly reduced (P < 0.05) under low external K+ and thus the relative reduction on protein synthesis was much less than that for cellular K+. These results indicate that while elevated intracellular K+ did not alter protein synthesis, reduced intracellular K+ correlated with a reduced cellular protein synthesis in HUVEC such that K+ may play a permissible role in the regulation of protein synthesis.

Nutritional evaluation of Chinese working women in the city of Tainan, Taiwan

Nutritional survey was conducted in 1994 in Tainan City, southern Taiwan. Total food duplicate samples were collected from 52 women volunteers. Clinical examinations, anthropometry, hematology and serum biochemistry were also conducted. The intakes of nutrients were estimated from the weights of food items in reference to the standard food composition tables for Taiwanese. On average, the participants took 1,973 kcal energy, 69 g protein, 73 g lipid and 269 g carbohydrate per day. Animal-based foods accounted for 49% and 36% of protein and lipid sources, respectively, but fish and shellfish contributed only 11% for protein and essentially nil for lipid. Lunch was the most substantial meal of the day. When classified by age (i.e., 22-29, 30-39 and 40-66 year-old groups), no age-related difference was detected among the three groups in all nutrients except for crude fiber. Comparison with recommended dietary allowance (RDA) for Taiwanese, the insufficiency ratios were more than 50% for minerals (i.e., Fe and Ca) and vitamins (except for vitamin C). Excess in the lipid energy ratio (> 30%) was observed in 60% of the study population. In agreement with this high lipid intake, 17% of the participants had BMI of > 25, and triglyceride levels were elevated (> 150 mg/100 ml) in 27%. There were no anemic case despite the low Fe intake (14 mg/day).

Nitric oxide inhibits migration of cultured endothelial cells

Endothelial cell migration is an important event in both physiological and pathophysiological processes. Although nitric oxide (NO) plays a critical role in regulating vascular functions, it is not known whether NO modulates migration of endothelial cells. We show here that chemically-derived NO inhibited the serum-induced migration of cultured human umbilical vein endothelial cells (HUVEC) in a time- and dose-dependent manner. The sensitivity of inhibition by S-nitroso-N-acetylpenicillamine (SNAP, a NO donor) was 2.36 +/- 1.032 x 10(-4) M (n = 4). This effect was attributed to NO since (1) other NO donor (e.g., sodium nitroprusside) also exhibited antimigratory effect, (2) pre-incubated SNAP (72 h) had no effect, (3) hemoglobin, a NO scavenger, eliminated the effect; while (4) superoxide dismutase, a NO protector, enhanced the antimigratory effect. Furthermore, 8-bromo-cGMP also inhibited the serum-induced migration of HUVEC. These data appear to support the notion that NO may serve as an important signaling molecule for neovascularization.

Background exposure of general population to cadmium and lead in Tainan city, Taiwan

Venous blood samples, 24-h total food duplicate samples, and rice samples were collected from 52 adult non-smoking women in the city of Tainan, southern Taiwan, in 1994, and analyzed for cadmium (Cd) and lead (Pb) by wet-digestion followed by graphite furnace atomic absorption spectrophotometry. Daily dietary intake was 10 micrograms for Cd and 22 micrograms for Pb as geometric means, of which Cd and Pb in rice accounted for 34% and 1.4% of daily Cd and Pb intakes, respectively. The counterpart values for blood were 1.11 ng/ml and 44.5 ng/ml for Cd and Pb, respectively. International comparison with recently published data suggests that the exposure to Cd in Tainan should be among the lowest in the world.

Earthworm and food interactions on bioaccumulation and disappearance in soil of polycyclic aromatic hydrocarbons: studies on phenanthrene and fluoranthene

The present study describes some novel phenomena with regard to the environmental fate of polycyclic aromatic hydrocarbons (PAHs) in the terrestrial soil environment. Laboratory experiments were conducted on: (1) the influence of earthworms on the disappearance rate of PAHs in soil, and (2) the bioaccumulation of these compounds in the earthworm body. It is demonstrated that the disappearance of phenanthrene and fluoranthene in soil is accelerated by the presence of the earthworm Lumbricus rubellus. Possible explanations and practical implications of this effect are discussed. In the bioaccumulation part of the study it is demonstrated that earthworms may take up and accumulate fluoranthene and, to a lesser extent, also phenanthrene in their body tissues. Bioaccumulation was found to be reduced by changes in bioavailability associated with aging of the PAH-amended soil. Finally, it was observed that earthworms indicate a strongly enhanced bioaccumulation of PAHs under conditions of food limitation.

Modelling and monitoring organochlorine and heavy metal accumulation in soils, earthworms, and shrews in Rhine-delta floodplains

In the Rhine-delta, accumulation of microcontaminants in floodplain foodwebs has received little attention in comparison with aquatic communities. To investigate organochlorine and metal concentrations in a terrestrial foodchain, samples of soil, earthworms (Lumbricus rubellus), and shrew (Crocidura russula, Sorex araneus) livers and kidneys were taken from two moderately to heavily polluted floodplains. Chlorobiphenyl residues in earthworm fat were 0.10 to 3.5 times the concentrations in soil organic matter, whereas ratios for other organochlorines varied between 0.87 and 8.8. These ratios are one order of magnitude lower than expected from laboratory experiments with earthworms, and laboratory and field studies on aquatic invertebrates. Bioconcentration ratios for heavy metals are in accordance with literature values for other locations, confirming the high potential for cadmium accumulation in Lumbricidae. Concentrations of organochlorines in shrew liver lipids were 1.0 to 13 times the residues in earthworm fat. These values are higher than lipid-corrected biomagnification ratios for laboratory rodents, but equal to those measured for benthivorous birds in the Rhine-delta. On a dry weight basis, kidney-earthworm ratios for cadmium were about one order of magnitude lower than previously reported values for insectivores. Soil concentrations of many compounds in both floodplains did not meet Dutch quality standards. Yet, hexachlorobenzene, chlorobiphenyl 153 (PCB153), gamma-hexachlorocyclohexane, sigma DDT, and dieldrin residues in earthworms and shrews did not exceed diet levels expected to be safe for endothermic species. An exception was noted for cadmium in worms and shrew kidneys. Heavy metal pollution in soil was close to levels that are critical to earthworms in laboratory studies. Cadmium concentrations in shrew kidneys were below levels suggested to be safe for Sorex araneus, but above those that were critical to the rat.

A risk-assessment model for toxic exposure of small mammalian carnivores to cadmium in contaminated natural environments

A model is presented to assess the risk of cadmium toxicity in mammalian wildlife in contaminated environments. The target-organ load was used as a hazard indicator and animals were considered to be at risk when a critical value, i.e. the lowest-observed-adverse-effect level (LOAEL), was attained or exceeded. The model was developed for Sorex araneus, a small mammalian predator with a high potential of attaining the critical target-organ load. Model parameter values were estimated from both explicit analysis of original field data and from theoretical considerations. A submodel was derived from linear regression of data concerning 36 field sites to predict the bioconcentration of cadmium in earthworms, an important food item of small mammalian carnivores. In addition to soil cadmium concentration several soil factors affecting cadmium bioavailability were included in the submodel. A second submodel was developed to predict target-organ load from a non-linear age-dependent regression of data on 63 predators from two different field sites. A separate theoretical model was constructed for the prediction of target-organ load as a function of pollutant ingestion, assimilation rates, and internal partitioning. The risk of cadmium exposure was assessed by estimating the EC50 value, the environmental effect concentration of a toxic substance in soil at which 50% of an adult population of predators would attain a target-organ load equal to or higher than the LOAEL. The model allows one to establish availability-differentiated soil quality standards with regard to cadmium pollution in natural environments. It predicts an exponential increase of the risk of hazardous exposure of terrestrial wildlife in areas sensitive to increasing levels of soil acidification ('chemical time bomb effect').

Hazardous exposure of ground-living small mammals to cadmium and lead in contaminated terrestrial ecosystems

The dietary exposure to cadmium and lead of two ground-living species of small mammals, i.e., shrews Sorex araneus (Insectivora) and voles Microtus agrestis (Rodentia), was investigated and related to metal loads in target organs (kidneys and liver). The study was done in two natural areas polluted with cadmium and lead originating from urban and industrial metal sources. The average intake of cadmium by the herbivorous voles varied between 0.1 and 0.4 micrograms/g/day and of lead between 2 and 10 micrograms/g/day. The carnivorous shrews showed a considerably higher metal intake rates, i.e., cadmium 3 to 16 micrograms/g/day and lead 19 to 53 micrograms/g/day, which was largely due to the consumption of contaminated earthworms (Oligochaeta). An average cadmium intake of 15 micrograms/g/day or a lead intake of 20 micrograms/g/day corresponded with critical renal metal loads of 120 micrograms/g for cadmium and 25 micrograms/g for lead, which are indicative of adverse health effects. The renal metal loads in shrews reached the critical level, but they remained far below this level in voles. The results indicate a greater risk of toxic exposure to cadmium and lead in soricine shrews than in microtine rodents.

Effect of soil pollution with metallic lead pellets on lead bioaccumulation and organ/body weight alterations in small mammals

Using small mammals as bioindicators, the bioavailable status and ecotoxicity of lead was investigated in an acidic sandy soil environment polluted with metallic lead pellets from shotgun ammunition. Average concentrations of lead in kidney, liver and bone tissue of wood mice (Apodemus sylvaticus), bank voles (Clethrionomys glareolus), and shrews (Sorex araneus) were strongly elevated, compared to tissue levels of conspecifics collected from an adjacent unpolluted area. All shrews and some bank voles collected from the shooting range exceeded the critical renal Pb concentration of 25 micrograms/g dry weight, considered diagnostic of lead intoxication in mammals. The geometric mean renal Pb concentration in shrews was 270 micrograms/g dry weight, with an upper range of more than 1,000 micrograms/g. The population of shrews and bank voles from the shooting range also showed a significantly increased average relative kidney weight (kidney-to-body weight ratio), which is indicative of lead poisoning. The results suggest that metallic lead pellets deposited in an acidic sandy soil are transformed to a chemical form of lead, probably Pb2+, which is toxic to organisms and which can readily enter the terrestrial food chain.

Toxicity and bioaccumulation of chlorophenols in earthworms, in relation to bioavailability in soil

The acute toxicity of five chlorophenols for two earthworm species was determined in two sandy soils differing in organic matter content and the results were compared with adsorption data. Adsorption increased with increasing organic matter content of the soils, but for tetra- and pentachlorophenol was also influenced by soil pH. Earthworm toxicity was significantly higher in the soil with a low level of organic matter. This difference disappeared when LC50 values were recalculated to concentrations in soil solution using adsorption data. Eisenia fetida andrei showed LC50 values lower than those of Lumbricus rubellus although bioaccumulation was generally higher in the latter species. Toxicity and bioaccumulation based on soil solution concentrations increased with increasing lipophilicity of the chlorophenols. The present results indicate that the toxicity and bioaccumulation and therefore the bioavailability of chlorophenols in soil to earthworms are dependent on the concentration in soil solution and can be predicted on the basis of adsorption data. Both the toxicity of and bioaccumulation data on chlorophenols in earthworms demonstrated surprisingly good agreement with those on chlorophenols in fish.

Electrophysiological evidence for chemosensitivity to adenosine, adenine and sugars in Spodoptera exempta and related species

Electrophysiological studies show that Spodoptera exempta and closely related species possess a receptor with specific sensitivity towards adenosine and adenine. 2 other types of receptors responded to certain sugars. The functional significance of these receptors in controlling chemoresponses of the larvae is discussed.

Structural modulations in the tsetse fly milk gland during a pregnancy cycle

Gross ultrastructural and histochemical details of the integumental milk glands of the tsetse fly Glossina morsitans have been examined during the pregnancy cycle. Structural evidence for protein secretion is found between Days 3-8 of the nine-day cycle: termination of activity is completed on the day of parturition. Onset of lactation is synchronized with the eclosion of the first instar larva. The changes in cell volume (notably in the extracellular reservoir) occurring throughout the pregnancy cycle are illustrated in electron micrographs, and a one hundred-fold volume increase in the reservoir volume between the inactive phase and the active period is illustrated and discussed in terms of membrane modulation of the limiting membrane of the reservoir. Intracellular membrane changes during the cycle, particularly the development of extensive ER arrays in the actively secreting cell, are illustrated and discussed. It is suggested that cytoplasmic microtubules play a part in maintaining the form of the distended secretory cell, at the height of secretory release and storage. Histochemical observations on the milk secretion, and the contents of the larval gut are presented.