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Selected AbstractsMetabolism of high density lipoprotein apolipoprotein A-I and cholesteryl ester in insulin resistant dog: a stable isotope studyDIABETES OBESITY & METABOLISM, Issue 1 2007F. Briand Aims:, In reverse cholesterol transport (RCT), hepatic Scavenger Receptor class B type I (SR-BI) plays an important role by mediating the selective uptake of high-density lipoprotein cholesteryl ester (HDL-CE). However, little is known about this antiatherogenic mechanism in insulin resistance. HDL-CE selective uptake represents the main process for HDL-CE turnover in dog, a species lacking cholesteryl ester transfer protein activity. We therefore investigate the effects of diet induced insulin resistance on RCT. Methods:, Five beagle dogs, in healthy and insulin resistant states, underwent a primed constant infusion of [1,213C2]acetate and [5,5,5- 2H3]leucine, as labelled precursors of CE and apolipoprotein (apo) A-I, respectively. Data were analysed using modelling methods. Results:, HDL-apo A-I concentration did not change in insulin resistant state but apo A-I absolute production rate (APR) and fractional catabolic rate (FCR) were both higher (2.2- and 2.4-fold, respectively, p < 0.05). HDL-CE levels were lower (1.2-fold, p < 0.05). HDL-CE APR and FCR were both lower (2.3- and 2-fold, respectively, p < 0.05), as well as selective uptake (2.6-fold, p < 0.05). Conclusions:, Lower HDL-CE selective uptake suggests that RCT is impaired in obese insulin resistant dog. [source] Characteristics of skin aging in Korean men and womenINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005J. H. Chung Introduction Korea is located between Japan and Mainland China. The people of these three countries have similar appearances and it is difficult to differentiate between them. Although the population of Asia is more than half of the total population of the Earth, the inherent characteristics of Asian skin have not been well investigated. Commercial markets for cosmetics and drugs for photoaged skin are rapidly expanding in many Asian countries. Therefore, many investigators in the field of dermatology and cosmetology have become interested in brown Asian skin. Clinical characteristics of skin aging and photoaging in Asians Skin aging can be divided into two basic processes: intrinsic aging and photoaging [1]. Intrinsic aging is characterized by smooth, dry, pale, and finely wrinkled skin, whereas photoaging, which indicates premature skin aging in chronically photodamaged skin, is characterized by severe wrinkling and irregular pigmentation. The pattern of wrinkling in Asians seems to differ from that in Caucasians. Asians have coarser, thicker and deep wrinkles, particularly in the forehead, perioral and Crow's foot areas. In contrast, Caucasians usually have relatively fine cheek and Crow's foot wrinkles. The reasons for these differences are not known and need further investigation. There are racial, ethnic and genetic differences, and differences of skin structure and function, between the brown skin of Asians and the white skin of Caucasians. As Asian skin is more pigmented, acute and chronic cutaneous responses to UV irradiation differ from those in white skin. Many people believe, based on clinical impressions, that the main process of photoaging in Asians involves pigmentary changes, rather than wrinkling. However, no study has been performed to confirm this belief. Risk factors for skin wrinkles and their relative risks in Korean skin [2] Various factors such as age, sun-exposure, and smoking are known to be important risk factors for wrinkles. However, the relative risks of each factor on wrinkles in the brown skin of Asians have not been investigated, and they could differ from those in Caucasians. An evaluation system for skin wrinkling is necessary for Asian skin [3]. Thus, we developed an eight-point photographic scale for assessing wrinkles in both Korean genders [2]. This scale can probably be applied to the populations of other Asian countries, at least to the Japanese and Chinese. The pattern of wrinkles in both genders appears to be similar. Age Age is an important risk factor for wrinkling in Asians, as in Caucasians. Korean subjects in their 60s showed a 12-fold increased risk of wrinkling, while subjects in their 70s have a 56-fold increased risk compared with young age group. UV light It is well known that the UV component in sunlight can cause and accelerate photoaging. The pigmented skin of Asian may better protect skin from acute and chronic UV damage. However, we found a strong association between sun-exposure and the development of wrinkling in Koreans. It was found that sun exposure of more than 5 h per day was associated with a 4.8-fold increased risk in wrinkling versus less than 2 h of sun-exposure in Koreans. Estrogen deficiency Korean females have more wrinkles than men, after controlling for age, sun exposure, and smoking, it was found that they have a 3.6-fold increased risk of developing wrinkles than their male counterparts [2]. It has also been reported, that the relative risk for wrinkling in women is higher than in men as for in white Caucasians [4]. The reason why women show more wrinkles remains to be determined. It is possible that a reduction in skin collagen because of estrogen deficiency in postmenopausal woman may aggravate wrinkling severity. Korean women with more than 10 years since menopause showed a 3.9-fold higher risk of wrinkling than the women 5 years of beyond menopause [5]. We demonstrated that women with a history of HRT have a significantly lower risk, more specifically, one fifth of the risk of facial wrinkling relative to those who had no history of HRT. Interestingly, we found that wrinkle severity significantly increased with an increasing number of full term pregnancies. The relative risk for severe wrinkling is increased by approximately 1.8-fold per full term pregnancy. Smoking It is known that smoking causes skin wrinkling in Caucasians, and that it plays no role in Blacks [6, 7]. Koreans with have a smoking history of more than 30 pack years showed a more than 2.8-fold increased risk of wrinkles [2]. The relative risks of wrinkles associated with a 30,50 pack-years history of smoking were 2.8- and 5.5-fold, respectively. Dyspigmentation in Asian skin To follow pigmentary changes, six photographic standards for both genders were developed for Korean skin, to produce a 6-point scale [2, 8]. Hyperpigmented spots, mostly lentigines, were prominent among women, while seborrheic keratosis tended to be more prominent in men. Seborrheic keratosis in Korean men Seborrheic keratoses (SKs) are benign cutaneous tumors. They have diverse clinical and histopathological appearances and are very common in the elderly (over 50 years old). The etiology of SKs is not well understood, although patients with a great number of lesionsshow a familial trait with an autosomal dominant pattern, and human papilloma virus has been suggested as possible cause because of verrucous appearance of the lesions. Exposure to sunlight has been suggested to be a risk factor for SKs. However, there is still some debate in terms of the role of sunlight. Recently, we have investigated the clinical characteristics of SKs and relationship between SKs and sunlight exposure in Korean males [9]. The prevalence of SKs in Koreans increases with age; it rose from 78.9% at 40 years, to 93.9% at 50 years and 98.7% in those over 60 years. Exposed areas, i.e. the face, neck and dorsum of the hands, demonstrate a significant increase in the prevalence of SKs by decade, whereas partly exposed areas, although SKs tended to increase in prevalence with age, this trend was not significant. When the estimated body surface area (BSA) is taken into account, the number of SKs on both the face and dorsum of the hands (0.51 ± 0.08 per 1% BSA) was over-represented compared with the trunk. SKs were also concentrated on the neck (0.38 ± 0.07 per 1% BSA) and in the V-area (0.47 ± 0.09 per 1% BSA). Outer forearms also showed 3-fold more SKs per unit area than neighboring arms and inner forearms, which are classified as partly exposed area (0.09 ± 0.02, 0.03 ± 0.01, respectively). The total area covered by SKs on exposed area also became significantly larger with aging than on intermittently exposed areas. These results indicate that exposure to sunlight might be related to SK growth. Our results indicated that excessive sun exposure is an independent risk factor of SKs. After controlling for age, smoking, and skin type, subjects with a sun exposure history of more than 6 hours per day showed a 2.28-fold increased risk of having severe SKs (n , 6) compared with those exposed for less that 3 h per day. These findings indicated that sun-exposure may play an important role in SK development. In summary, SKs are very common in Korean males and represent one of the major pigmentary problems. SKs concentrate on exposed skin, especially on the face and dorsum of the hands. Both age and lifetime cumulative sunlight exposure are important contributing factors and may work in a synergistic manner. Conclusion Many people tend to believe that wrinkles are not a prominent feature of Asian photoaged skin, and that dyspigmentation is a major manifestation in Asian skin. Contrary to this impression, wrinkling is also a major problem in the photoaged skin of Asians, and Korean people showing severe pigmentary changes usually tend to have severe wrinkles. In conclusion, the wrinkling patterns and pigmentary changes of photoaged skin in East Asians differ from those of Caucasians, and the relative risks of aggravating factors may be different from those of Caucasian skin. References 1.,Gilchrest, B.A. Skin aging and photoaging: an overview. J. Am. Acad. Dermatol. 21, 610,613 (1989). 2.,Chung, J.H. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 3.,Griffiths, C.E. et al. A photonumeric scale for the assessment of cutaneous photodamage. Arch. Dermatol. 128, 347,351 (1992). 4.,Ernster, V.L. et al. Facial wrinkling in men and women, by smoking status. Am. J. Public Health. 85, 78,82 (1995). 5.,Youn, C.S. et al. Effect of pregnancy and menopause on facial wrinkling in women. Acta Derm. Venereol. 83, 419,424 (2003). 6.,Kadunce, D.P. et al. Cigarette smoking: risk factor for premature facial wrinkling. Ann. Intern. Med. 114, 840,844 (1991). 7.,Allen, H.B., Johnson, B.L. and Diamond, S.M. Smoker's wrinkles? JAMA. 225, 1067,1069 (1973). 8.,Chung, J.H. Photoaging in Asians. Photodermatol. Photoimmunol. Photomed. 19, 109,121 (2003). 9.,Kwon, O.S. et al. Seborrheic keratosis in the Korean males: causative role of sunlight. Photodermatol. Photoimmunol. Photomed. 19, 73,80 (2003). [source] The influence of pH and digestion with commercial enzymes on calcium adsorption in casabeINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2006Petra Beatriz Navas Summary The Ca2+ binding capacity of a sample of casabe made from cassava (Manihot esculenta) was evaluated by using adsorption isotherms after a digestion process with commercial enzymes. It was found that enzymatic treatment increased the ability of vegetable material to retain calcium and to release endogenous mineral ions as a consequence of possible modifications to the carbohydrate matrix. Untreated casabe did not release mineral ions. pH also influenced the retention of Ca2+: at pH 4.5 release was the main process but adsorption increases with alkalinity up to pH 8.5. The Ca concentrations at which neither adsorption nor release occurred [Ca2+]e were as follows: 5.2 mm (pH 4.5), 3.5 mm (pH 7.1), and 0.63 mm (pH 8.5). The pH effect was explained by an increase in the density of negatively charged functional groups produced by ionization reactions at pH below the point of zero net charge (pHo) which was evaluated by using the Gouy,Chapman double layer model. Values of pHo were 6.4 for raw material and 4.1 after digestion with enzymes. In both cases, the density of positively charged sites below pHo was much higher that the density of negatively charged sites above pHo. [source] The value and correlation between PRL-3 expression and matrix metalloproteinase activity and expression in human gliomasNEUROPATHOLOGY, Issue 6 2007Lingfei Kong Local invasion of tumor cells is characteristic of most human glioma invasions. It is associated with increased motility and a potential to degrade the extracellular matrix. Matrix metalloproteinases (MMPs) have been proved to be a main process in local invasion of brain tumor. PRL-3 is a new protein tyrosine phosphatase which would also degrade the extracellular matrix and has been proved to be expressed in liver metastases derived from colorectal cancer. In this study, we sought to investigate the expression of PRL-3 in glioma tissues and investigate the relationship between MMPs (MMP2, MMP9, membrane-type matrix metalloproteinase 1 [MT1-MMP]) activity and expression in gliomas. The modifications of in situ hybridization of mRNA phosphatase of regenerating liver-3 (PRL-3) methods are preformed in the study of paraffin-embedded slides. The immunohistochemistry and gelatin zymography are used to detect the expression of PRL-3 and activity of MMPs. The results show that PRL-3 mRNA and antibody of PRL-3 are detected in glioma tissues mainly in grades IV and III, only a little in grade II, but not in normal brain tissue and glioma grade I. MMP2 and MMP9 are observed mainly in glioma tissues of grades IV and III in activity and expression. MT1-MMP protein is located in glioma tissues and vessel endothelial cells. This is the first report of detecting PRL-3 expression in gliomas, especially in grades III and IV, which may play an important role in progression of gliomas. PRL-3, MMP2 and MT1-MMP cooperatively contribute to gliomas invasion. Intermediate MMP2 (MT1-MMP, TIMP-2, MMP2 trimeric complex) is detected in high grades of glioma tissues by gelatin zymography and may be a marker indicating latent malignance of gliomas. [source] Astroglial structures in the zebrafish brain,THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 21 2010Larissa Grupp Abstract Parasagittal cryostat section through the dorsal zebrafish telencephalon stained with antibodies binding to glial fibrillary acidic protein (GFAP; red) and glutamine synthetase (GS; green). Long radial glial fibers were positive for both proteins with GFAP present in the main process and branches (yellow), and GS additionally in finer branches (green areas). Cell nuclei were stained with TOPRO (blue). Note that glial cell bodies are lining the ventricular surface of the everted telencephalon. The Journal of Comparative Neurology, Volume 518, Number 21, 4277,4287. [source] Modelling the wet deposition of reduced nitrogen over the British Isles using a Lagrangian multi-layer atmospheric transport modelTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 606 2005N. Fournier Abstract Wet deposition of reduced nitrogen is estimated for the United Kingdom using a Lagrangian long-term, long-range atmospheric transport model. Such long-range transport models are used to develop emission-control strategies to combat environmental acidification in the sensitive regions of the United Kingdom and Europe. These models currently consider the wet deposition as a loss term using scavenging rates and a simple seeder,feeder effect. The seeder,feeder effect is assumed to be the main process producing orographic precipitation since the majority of British Isles annual rainfall falls in frontal events. This paper focuses on the analysis of different parametrizations of the removal process by wet deposition. It is shown that the seeder,feeder effect is very dependent on flow direction. Therefore, a model of directional orographic enhancement of precipitation is developed to simulate this effect. A revised formulation of the wet deposition parametrization is suggested, incorporating the directional orographic precipitation produced with this model. This new formulation also takes into account the larger concentrations of ions dissolved in rain water measured in mountainous areas. Moreover, a new representation of the wet deposition process is developed by considering explicitly the mixing layer's depth calculated in the model. The results from the atmospheric model, with these revised parametrizations of the wet deposition, are then compared with measured wet deposition of reduced nitrogen. Firstly, with the new directional orographic rainfall, the modelled United Kingdom reduced nitrogen wet deposition budget is still underestimated but an increased correlation with measurements is obtained. Secondly, the inclusion of the calculated mixing layer's depth leads to a considerable improvement in the modelled reduced nitrogen wet deposition budget compared with measurements. Copyright © 2005 Royal Meteorological Society. [source] Comparison of apoptosis and mortality measurements in peripheral blood mononuclear cells (PBMCs) using multiple methodsCELL PROLIFERATION, Issue 5 2005S. Glisic-Milosavljevic Death through apoptosis is the main process by which aged cells that have lost their function are eliminated. Apoptotic cells are usually detected microscopically by changes in their morphology. However, determination of early apoptotic events is important for in vitro (and ex vivo) studies. The main objective of the present study is to find the most sensitive method for apoptosis detection in human peripheral blood mononuclear cells (PBMCs) by comparing six different methods following five different means of immunological stimulation at 3 and 5 days. Each of six apoptosis quantification methods, except the trypan blue exclusion test, is a combination of two stains, one for the specific detection of apoptotic cells and the other for the unspecific detection of dead cells. Values for apoptosis and mortality were compared with a reference method. The choice of apoptosis detection method is more important following 3 days of stimulation than after 5 days of stimulation (P = 2 × 10,6 versus P = 1 × 10,2). In contrast, we find mortality measurements following the different means of stimulation highly significant at both 3 and 5 days (F2.28 = 7.9, P = 1.4 × 10,6 at 3 days and F2.28 = 8.5, P = 4.5 × 10,7 at 5 days). Variation as a result of the combination of specific PBMC stimulation and the method used to detect apoptosis is reduced considerably with time (F1.58 + 3.7, P + 3 × 10,7 at 3 days to F = (1.58) = 0.97, P = 0.5 at 5 days). Based on Tukey's test, YO-PRO-1 is the most sensitive stain for apoptosis and, when combined with 7-AAD, provides an accurate measure of apoptosis and mortality. In conclusion, we propose YO-PRO-1/7-AAD as a new combination and low-cost alternative for the sensitive detection of early apoptosis. [source] Interactions of ferricyanide with humic soils and charred strawEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008T. Rennert Summary The iron-cyanide complexes ferricyanide, [FeIII(CN)6]3,, and ferrocyanide, [FeII(CN)6]4,, are anthropogenic contaminants in soil. We studied the interactions of ferricyanide with humic soils and charred straw (maize and rye, both charred at 300, 400 and 500°C) by batch experiments and Fourier transform infrared (FTIR) spectroscopy. All soil samples sorbed ferricyanide (up to 8.4 g kg,1). Precipitation of a manganese ferrocyanide after reduction of ferricyanide in the moderately acidic to neutral soils was deduced from both FTIR spectroscopy (CN absorption bands at 2069,2065 cm,1) and geochemical modelling. Ferricyanide was also adsorbed onto the charred straw. The amounts of iron-cyanide complexes adsorbed increased with increasing charring temperature, with a maximum of 1.71 g kg,1. An absorption band at 2083 cm,1 indicated weakly adsorbed intermediates of the reduction of ferricyanide to ferrocyanide. This band disappeared in the samples charred at higher temperature, whereas a band at 2026 cm,1 was present in all spectra and became intensified in the high-temperature straw. We attribute this band to ferrocyanide forming inner-sphere complexes, presumably with quinone species of the organic matter. The band at 2026 cm,1 was also present in the spectra of the soils, indicating that soil organic matter also adsorbs ferrocyanide. However, in humic soils the main processes of ferricyanide interaction include reduction to ferrocyanide and precipitation as manganese ferrocyanide. Quantitatively, adsorption on highly aromatic substances plays only a less important role as compared with precipitation. [source] REPRESSION OF COMPETITION AND THE EVOLUTION OF COOPERATIONEVOLUTION, Issue 4 2003Steven A. Frank Abstract Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study. [source] Recent decay of a single palsa in relation to weather conditions between 1996 and 2000 in Laivadalen, northern SwedenGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2002Frieda Sjoukje Zuidhoff This study presents the decay of a small palsa complex between 1996 and 2000 in Sweden's southernmost major palsa bog. The outline of the palsa was mapped during three summers in 1996, 1999 and 2000 and an automatic weather station measured air temperature, precipitation, snow depth, wind speed and wind direction between 1997 and 2000. The decay of the palsa was enormous in the dome,shaped part of the palsa complex: the height decreased during the observation period from 2.3 m to 0.5 m. In 2000, the palsa dome had almost totally disappeared: only some peat blocks in a palsa pond were left. The decay of the palsa was complex with a number of degradational processes, of which the main processes were block erosion, thermokarst and wind erosion. Thermal melting has occurred along the edges of the palsa and possibly below the frozen core of the palsa since 1998/99. Wind erosion was observed during summer and the maximum estimated deflation was 80 cm. The decay of the palsa dome was especially large between 1999 and 2000, probably due to a high mean annual temperature, high summer precipitation and the warming influence of the large pond surrounding the palsa. The present climate in the palsa bog with a mean annual temperature of ,0.8°C is not favourable for palsa development and maintenance, despite a strong wind regime which can provide suitable conditions for snowdrift. [source] Evaluation of model complexity and space,time resolution on the prediction of long-term soil salinity dynamics, western San Joaquin Valley, CaliforniaHYDROLOGICAL PROCESSES, Issue 13 2006G. Schoups Abstract The numerical simulation of long-term large-scale (field to regional) variably saturated subsurface flow and transport remains a computational challenge, even with today's computing power. Therefore, it is appropriate to develop and use simplified models that focus on the main processes operating at the pertinent time and space scales, as long as the error introduced by the simpler model is small relative to the uncertainties associated with the spatial and temporal variation of boundary conditions and parameter values. This study investigates the effects of various model simplifications on the prediction of long-term soil salinity and salt transport in irrigated soils. Average root-zone salinity and cumulative annual drainage salt load were predicted for a 10-year period using a one-dimensional numerical flow and transport model (i.e. UNSATCHEM) that accounts for solute advection, dispersion and diffusion, and complex salt chemistry. The model uses daily values for rainfall, irrigation, and potential evapotranspiration rates. Model simulations consist of benchmark scenarios for different hypothetical cases that include shallow and deep water tables, different leaching fractions and soil gypsum content, and shallow groundwater salinity, with and without soil chemical reactions. These hypothetical benchmark simulations are compared with the results of various model simplifications that considered (i) annual average boundary conditions, (ii) coarser spatial discretization, and (iii) reducing the complexity of the salt-soil reaction system. Based on the 10-year simulation results, we conclude that salt transport modelling does not require daily boundary conditions, a fine spatial resolution, or complex salt chemistry. Instead, if the focus is on long-term salinity, then a simplified modelling approach can be used, using annually averaged boundary conditions, a coarse spatial discretization, and inclusion of soil chemistry that only accounts for cation exchange and gypsum dissolution,precipitation. We also demonstrate that prediction errors due to these model simplifications may be small, when compared with effects of parameter uncertainty on model predictions. The proposed model simplifications lead to larger time steps and reduced computer simulation times by a factor of 1000. Copyright © 2006 John Wiley & Sons, Ltd. [source] Population structure in the South American tern Sterna hirundinacea in the South Atlantic: two populations with distinct breeding phenologiesJOURNAL OF AVIAN BIOLOGY, Issue 4 2010Patrícia J. Faria The South American tern Sterna hirundinacea is a migratory species for which dispersal, site fidelity and migratory routes are largely unknown. Here, we used five microsatellite loci and 799,bp partial mitochondrial DNA sequences (Cytochrome b and ND2) to investigate the genetic structure of South American terns from the South Atlantic Ocean (Brazilian and Patagonian colonies). Brazilian and Patagonian colonies have two distinct breeding phenologies (austral winter and austral summer, respectively) and are under the influence of different oceanographic features (e.g. Brazil and Falklands/Malvinas ocean currents, respectively), that may promote genetic isolation between populations. Results show that the Atlantic populations are not completely panmictic, nevertheless, contrary to our expectations, low levels of genetic structure were detected between Brazilian and Patagonian colonies. Such low differentiation (despite temporal isolation of the colonies) could be explained by demographic history of these populations coupled with ongoing levels of gene flow. Interestingly, estimations of gene flow through Maximum likelihood and Bayesian approaches has indicated asymmetrical long term and contemporary gene flow from Brazilian to Patagonian colonies, approaching a source,sink metapopulation dynamic. Genetic analysis of other South American tern populations (especially those from the Pacific coast and Falklands,Malvinas Islands) and other seabird species showing similar geographical distribution (e.g. royal tern Thalasseus maximus), are fundamental in gaining a better understanding of the main processes involved in the diversification of seabirds in the southern hemisphere. [source] Gas-phase ion chemistry in the ternary SiH4,C3H6,PH3 systemJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2002Stefania Calderan Abstract Propene,phosphine and the silane,propene,phosphine gaseous mixtures were studied by ion trap mass spectrometry. For the binary mixture the variation of ion abundances under different partial pressures and the mechanisms of ion,molecule reactions are reported. Moreover, the rate constants of the main processes were measured and compared with the collisional rate constants to determine the reaction efficiencies. In the ternary silane,propene,phosphine mixture the mechanisms of formation of ion clusters were elucidated, but the complexity of the system and the low abundances of the ions usually isolated by successive steps prevented the determination of rate constants. The hydrogenated ternary ions are mainly formed by reactions of ions with propene, whereas a minor contribution comes from reactions of ions with phosphine. The ions show very low reactivity with silane. The formation processes of these species are discussed in relation to their possible role as precursors of amorphous silicon carbides doped with phosphorus obtained by deposition from properly activated silane,propene,phosphine mixtures. Copyright © 2001 John Wiley & Sons, Ltd. [source] Polyphase zircon in ultrahigh-temperature granulites (Rogaland, SW Norway): constraints for Pb diffusion in zirconJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2002A. Möller Abstract SHRIMP U,Pb ages have been obtained for zircon in granitic gneisses from the aureole of the Rogaland anorthosite,norite intrusive complex, both from the ultrahigh temperature (UHT; >900 °C pigeonite-in) zone and from outside the hypersthene-in isograd. Magmatic and metamorphic segments of composite zircon were characterised on the basis of electron backscattered electron and cathodoluminescence images plus trace element analysis. A sample from outside the UHT zone has magmatic cores with an age of 1034 ± 7 Ma (2,, n = 8) and 1052 ± 5 Ma (1,, n = 1) overgrown by M1 metamorphic rims giving ages between 1020 ± 7 and 1007 ± 5 Ma. In contrast, samples from the UHT zone exhibit four major age groups: (1) magmatic cores yielding ages over 1500 Ma (2) magmatic cores giving ages of 1034 ± 13 Ma (2,, n = 4) and 1056 ± 10 Ma (1,, n = 1) (3) metamorphic overgrowths ranging in age between 1017 ± 6 Ma and 992 ± 7 Ma (1,) corresponding to the regional M1 Sveconorwegian granulite facies metamorphism, and (4) overgrowths corresponding to M2 UHT contact metamorphism giving values of 922 ± 14 Ma (2,, n = 6). Recrystallized areas in zircon from both areas define a further age group at 974 ± 13 Ma (2,, n = 4). This study presents the first evidence from Rogaland for new growth of zircon resulting from UHT contact metamorphism. More importantly, it shows the survival of magmatic and regional metamorphic zircon relics in rocks that experienced a thermal overprint of c. 950 °C for at least 1 Myr. Magmatic and different metamorphic zones in the same zircon are sharply bounded and preserve original crystallization age information, a result inconsistent with some experimental data on Pb diffusion in zircon which predict measurable Pb diffusion under such conditions. The implication is that resetting of zircon ages by diffusion during M2 was negligible in these dry granulite facies rocks. Imaging and Th/U,Y systematics indicate that the main processes affecting zircon were dissolution-reprecipitation in a closed system and solid-state recrystallization during and soon after M1. [source] Ex vivo assessment of mouse cervical remodeling through pregnancy via 23Na MRSNMR IN BIOMEDICINE, Issue 8 2010Xiang Xu Abstract Preterm birth occurs in 12.5% of births in the United States and can lead to risk of infant death or to lifelong serious health complications. A greater understanding by which the two main processes, uterine contraction and cervical remodeling are regulated is required to reduce rates of preterm birth. The cervix must undergo extensive remodeling through pregnancy in preparation for parturition, the process of labor and delivery of young. One key aspect of this dynamic process is a change in the composition and abundance of glycosaminoglycans (GAGs) and proteoglycans within the extracellular matrix, which influences the loss of tensile strength or stiffness of the cervix during labor. 23Na NMR spectroscopy has previously been validated as a method to quantify GAGs in tissues. In the current study, the Na+ concentration was measured at several time points through pregnancy in mouse cervices using 23Na NMR spectroscopy. The Na+ concentration increased progressively during pregnancy and peaked one day before birth followed by a rapid decline after birth. The same trend was seen in GAGs as measured by a biochemical assay using independent cervix samples over the course of pregnancy. We suggest that monitoring the Na+ concentration via 23Na NMR spectroscopy can serve as an informative physiological marker in evaluating the stages of cervical remodeling ex vivo and warrants further investigation to determine its utility as a diagnostic tool for the identification of women at risk for impending preterm birth. Copyright © 2010 John Wiley & Sons, Ltd. [source] Immunoglobulin uptake and processing by Schistosoma mansoniPARASITE IMMUNOLOGY, Issue 9 2006C. THORS SUMMARY Intravascular Schistosoma mansoni worms seem to take up immunoglobulins from blood by surface Fc-receptors, but the process whereby bound immunoglobulins are processed by the parasite is poorly understood. We here present morphological data suggesting that two distinct main processes are involved: Host immunoglobulins were seen at two distinct locations in the parasite: in the frontal part of the enteric tube, the oesophagus, and as a fine granular staining at the surface and in the subtegumental region. The latter staining pattern corresponds to host immunoglobulin localization in discrete organelle-like aggregates tentatively identified as ,discoid or elongate bodies' at the ultrastructural level using immunogold staining. Immunoglobulin uptake by intravascular worms was also demonstrated in vivo after passive administration of 125I-labelled rabbit and mouse immunoglobulins. Radiolabelled immunoglobulins were taken up by the worms and shown to localize as fine strands running perpendicular to the parasite surface. Our results suggest that intravascular schistosomes take up host immunoglobulins both as part of their enteric digestion and by a surface Fc-receptor-mediated mechanism, involving transport and processing within organelles, ,elongate bodies'. Immunoglobulins taken up by intravascular schistosomes form a distinct organelle-like granules, which seem to be processed within the excretory system of the parasite. [source] Discourse Resistance And Negotiation By Indigenous AustraliansPEACE & CHANGE, Issue 2 2003John Synott In the context of intercultural relations, the boundaries between dominant and subordinated communities are constructed in a variety of ways. Language frames, or discourses, understood from a sociological rather than a linguistic perspective can be considered to constitute one of the main processes for determining the character of intercultural boundaries. Using this theoretical perspective, this article examines a number of discourses that have contributed to the construction of social relations between Australian Aborigines and the dominant nonindigenous cultural groups in Australia. Examples from the colonial period show the way in which indigenous people were oppressed along racial boundaries, even as they resisted, while more recent instances chart the process of indigenous people in renegotiating social relations and in asserting the process of self-determination and cultural celebration. [source] Thermal degradation of a brominated bisphenol a derivativePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2003M. P. Luda Abstract The thermal degradation of 2,6,2,,6,,tetrabromo-4,4,-isopropylidene-di phenol (tetrabromobisphenol A) (TBBPA) has been investigated and a mechanism for its thermal degradation is suggested. TBBPA is a comonomer widely used in epoxy and in unsaturated polyester resins to impart fire retardance. These resins find a common use in electric and electronic equipment. The presence of bromine atoms is the key factor in fire retardant activity, while on the other hand it represents an ecological problem when pyrolytic recycling is programmed at the end of the useful life of such items. However, pyrolysis is the more advantageous recycling system for thermosetting resins and thus efforts should be made to control the pyrolysis in order to avoid or minimize the development of toxics. Homolytic scission of the aromatic bromine and condensation of aromatic bromine with phenolic hydroxyl are the main processes occurring in the range 270,340°C. A large amount of charred residue is left as a consequence of condensation reactions. HBr and brominated phenols and bisphenols are the main volatile products formed. Brominated dibenzodioxins structures are included in the charred residue and not evolved in the volatile phases. Copyright © 2003 John Wiley & Sons, Ltd. [source] Astroglial structures in the zebrafish brain,THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 21 2010Larissa Grupp Abstract To understand components shaping the neuronal environment we studied the astroglial cells in the zebrafish brain using immunocytochemistry for structural and junctional markers, electron microscopy including freeze fracturing, and probed for the water channel protein aquaporin-4. Glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) showed largely overlapping immunoreactivity: GFAP in the main glial processes and GS in main processes and smaller branches. Claudin-3 immunoreactivity was spread in astroglial cells along their major processes. The ventricular lining was immunoreactive for the tight-junction associated protein ZO-1, in the telencephalon located on the dorsal, lateral, and medial surface due to the everting morphogenesis. In the tectum, subpial glial endfeet were also positive for ZO-1. Correspondingly, electron microscopy revealed junctional complexes between subpial glial endfeet. However, in freeze-fracture analysis tight junctional strands were not found between astroglial membranes, either in the optic tectum or in the telencephalon. Occurrence of aquaporin-4, the major astrocytic water channel in mammals, was demonstrated by polymerase chain reaction (PCR) analysis and immunocytochemistry in tectum and telencephalon. Localization of aquaporin-4 was not polarized but distributed along the entire radial extent of the cell. Interestingly, their membranes were devoid of the orthogonal arrays of particles formed by aquaporin-4 in mammals. Finally, we investigated astroglial cells in proliferative areas. Brain lipid basic protein, a marker of early glial differentiation but not GS, were present in some proliferation zones, whereas cells lining the ventricle were positive for both markers. Thus, astroglial cells in the zebrafish differ in many aspects from mammalian astrocytes. J. Comp. Neurol. 518:4277,4287, 2010. © 2010 Wiley-Liss, Inc. [source] Kinetic modeling of light limitation and sulfur deprivation effects in the induction of hydrogen production with Chlamydomonas reinhardtii: Part I. Model development and parameter identificationBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Swanny Fouchard Abstract Chlamydomonas reinhardtii is a green microalga capable of turning its metabolism towards H2 production under specific conditions. However this H2 production, narrowly linked to the photosynthetic process, results from complex metabolic reactions highly dependent on the environmental conditions of the cells. A kinetic model has been developed to relate culture evolution from standard photosynthetic growth to H2 producing cells. It represents transition in sulfur-deprived conditions, known to lead to H2 production in Chlamydomonas reinhardtii, and the two main processes then induced which are an over-accumulation of intracellular starch and a progressive reduction of PSII activity for anoxia achievement. Because these phenomena are directly linked to the photosynthetic growth, two kinetic models were associated, the first (one) introducing light dependency (Haldane type model associated to a radiative light transfer model), the second (one) making growth a function of available sulfur amount under extracellular and intracellular forms (Droop formulation). The model parameters identification was realized from experimental data obtained with especially designed experiments and a sensitivity analysis of the model to its parameters was also conducted. Model behavior was finally studied showing interdependency between light transfer conditions, photosynthetic growth, sulfate uptake, photosynthetic activity and O2 release, during transition from oxygenic growth to anoxic H2 production conditions. Biotechnol. Bioeng. 2009;102: 232,245. © 2008 Wiley Periodicals, Inc. [source] Dendrimers: A Mimic Natural Light-Harvesting SystemCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2010Yi Zeng Dr. Abstract In natural photosynthetic systems, a large array of chlorophyll molecules surrounds a single reaction center and channels the absorbed solar energy to the reaction center, ultimately resulting in ATP production. Dendrimers are well-defined tree-like macromolecules having numerous chain ends all emanating from a single core, which makes them an attractive candidate for light-harvesting applications. More importantly, their synthesis is controllable and the accurate positioning of chromophores can be achieved. Photoinduced electron transfer and energy transfer are main processes involved in photosynthesis. Studies on these processes in dendritic systems are important for the future application of dendrimers in optoelectronic devices. In this Focus Review we will discuss recent advances of light-harvesting dendrimers and emphasize the energy transfer and electron transfer characteristics in these systems. [source] | ||||||||||||||||||||||