UN system efforts to support the response to AIDS in China

INTRODUCTION China has made considerable progress in the response to the AIDS epidemic in the past years, particularly in terms of commitment by the national leadership, the establish- ment of a supportive policy framework, improved under- standing of the…     

Multi-element isotope fractionation concepts to characterize the biodegradation of hydrocarbons — from enzymes to the environment

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A data-driven framework to model the organism–environment system

Organisms modify their development and function in response to the environment. At the same time, the environment is modified by the activities of the organism. Despite the ubiquity of such dynamical interactions in nature, it remains challenging to develop models that accurately represent them, and that can be fitted using data. These features are desirable when modeling phenomena such as phenotypic plasticity, to generate quantitative predictions of how the system will respond to environmental signals of different magnitude or at different times, for example, during ontogeny. Here, we explain a modeling framework that represents the organism and environment as a single coupled dynamical system in terms of inputs and outputs. Inputs are external signals, and outputs are measurements of the system in time. The framework uses time-series data of inputs and outputs to fit a nonlinear black-box model that allows to predict how the system will respond to novel input signals. The framework has three key properties: it captures the dynamical nature of the organism–environment system, it can be fitted with data, and it can be applied without detailed knowledge of the system. We study phenotypic plasticity using in silico experiments and demonstrate that the framework predicts the response to novel environmental signals. The framework allows us to model plasticity as a dynamical property that changes in time during ontogeny, reflecting the well-known fact that organisms are more or less plastic at different developmental stages.     

United Nations system efforts to support the response to AIDS in China

In the last two years, we have seen a remarkable intensification in the response to AIDS in China. A number of organizations have joined and contributed to the efforts of the Chinese government in responding the AIDS epidemic in China. This article specifically describes the role of the United Nations in supporting and strengthening those responses. Achievements of the United Nations （UN） highlighted in the article include： strengthened leadership and political commitment to respond to AIDS; improved HIV/AIDS surveillance and information; expanded prevention efforts; improved treatment, care and support to people living with HIV and increased resources for AIDS programs. Additional roles of the United Nations system in the near future include strengthening national leadership by supporting the ‘three ones＇, i. e., one national plan on AIDS; one national coordinating authority for AIDS; and one monitoring and evaluation system for AIDS. In addition, the UN system is expected to strengthen alignment and harmonization of activities of all international organizations and improved accountability and oversight. Remaining challenges identified include increasing awareness of AIDS and reducing stigma and discrimination; reducing vulnerability and risk behaviour among specific groups; providing improved treatment, care and support for people living with HIV; promoting stronger engagement by civil society, and; addressing the gender dimensions of AIDS.     

A mathematical model to predict the tissue response to parthenin — An allelochemical

Parthenin — a sesquiterpene lactone fromParthenium hysterophorus L. is an allelochemical that prevents the germination ofPhaseolus aureus Roxb. cv. ML-5 seeds. The response of the seed has been attributed to the inhibition of the respiratory electron transport ability of its embryo. It has been shown to depend directly not only upon concentration of parthenin, but simultaneously on the duration of exposure of the seeds to the chemical as well. A strong correlation exists between the quantum of the response and the product of the period of exposure and the concentration of parthenin. In order to predict the maximum possible germination ability of the seed exposed for a given period to a given concentration of parthenin, an expression X = 10000 Y³ / [e^Y/0.31-1] was formulated from the equation X = AY³/[e^Y/Y0-1], where X represents values of maximum respiratory activity, Y represents the product of concentration and time in units mg cn^-3 h, A represents a dimensional constant. The trend and nature of response that is calculated on the basis of formulation coincides with that of measured response through spectrophotometry.     

Is the lipolytic response in porcine adipose tissue slices equivalent to the lipolytic response in isolated adipocytes?

• 1.1. In most cases, when isolated adipocytes and adipose tissue slices from the same animal were stimulated with various lipolytic agents (adrenergie agonists, theophylline, adenosine deaminase), the qualitative response was similar.
• 2.2. There were, however, numerous exceptions; e.g. quinterenol did not affect isolated adipocytes whereas it was a partial agonist for adipose slices from the same animal.
• 3.3. The adipocytes present in slices were larger than those isolated from slices by collagenase digestion.
• 4.4. Isolated adipocytes were not more sensitive than tissue slices to stimulation by lipolytic agents.

     

Is the response of aphids to alarm pheromone stable?

Aphid taxa are characterized by a number of biological features, such as their feeding behaviour and host selection, which it is generally accepted are affected by keeping them for several generations under standard conditions in a laboratory. Analyses of three strains of the green pea aphid, Acyrthosiphon pisum (Harris, 1776), reared in culture for long periods, indicate that other characters are also affected. For example, the response of these aphids to alarm pheromone is dramatically reduced. This raises an interesting question regarding the mechanism by which it occurs and has consequences when aphids from laboratory cultures are used for studies in ecology and applied biology and especially the long‐term effectiveness of crop plants genetically engineered to produce EBF as a means of controlling aphids.     

Does the response of the intestinal epithelium to keratinocyte growth factor vary according to the method of administration?

BACKGROUND: Keratinocyte growth factor (KGF) is a potent mitogen and may be of value for the treatment of conditions such as short bowel syndrome and chemotherapy-induced mucositis. However the most efficacious route and method of administration is unclear. METHODS: Rats maintained by total parenteral nutrition (TPN) were given KGF (1 mg/kg/rat/day, i.v.) infused continuously or as a once-daily injection. The same dose was also given s.c. to chow-fed rats. Changes in gut growth were assessed by measurement of wet weight, proliferation (vincristine induced metaphase arrest) and crypt branching index. Changes in gut hormone profile were also determined to examine if any trophic effects were mediated via this mechanism. RESULTS: KGF caused a 70-100% increase in wet weight of the stomach, small and large intestine of TPN-fed rats (P < 0.01) with no significant differences seen between the two methods of administration. The increase in metaphase counts was greatest in the stomach (about seven-fold P < 0.01), but was less pronounced in the distal small intestine and colon (about 50% increase). The trophic effect of KGF was much less prominent in orally-fed rats. Crypt branching index was significantly reduced by KGF in the proximal small intestine of TPN, but not orally-fed rats. Plasma gastrin, PYY, total glucagon, enteroglucagon and GLP-1 all increased by two-three-fold (all P < 0.01) in response to KGF whereas insulin levels fell by about 25% in the TPN group. CONCLUSIONS: The mitogenic action of KGF occurred predominantly in the stomach and proximal small intestine. Its efficacy was less pronounced in orally-fed animals, suggesting KGF may be of greatest benefit in conditions associated with lowered intestinal proliferation. Clinical trials of KGF can probably use single daily i.v. injections without reduction in efficacy.     

Characterization of the γδ T cell response to acute leukemia

Background: Previous work from our center has suggested a correlation between increased donor-derived Vδ1+ γδ T cells and long-term relapse-free survival following bone marrow transplantation for leukemia. Questions remain, however, as to whether this observation can be explained by a γδ T cell-based immune response against primary leukemia. Methods: We examined γδ T cell receptor (TCR) phenotype, cell proliferation, and cytolytic activity following culture with irradiated primary leukemia blasts from a haploidentical first-degree relative. Subsequently, we also studied the γδ TCR phenotype and complimentarity determining region 3 (CDR3) cDNA sequences from 17 newly diagnosed leukemia patients. Results: In 17/28 (61%) of in vitro cultures, γδ T cells proliferated in culture with primary blasts. Vδ1+ T cells were proportionally increased in all cultures and were the predominant cell population in 6/17. In the 7 cultures where cytotoxicity could be assessed, 6 (86%) showed some degree of cytotoxicity to the primary leukemia. Vδ1+ T cells were also the predominant γδ T cell subtype in pre-treatment leukemia patients principally due to loss of Vδ2+ T cells rather than expansion of Vδ1+ cells. The Vδ1 CDR3-region cDNA sequence from these patients revealed exclusive use of the Jδ1 constant region and sequence conservation in 4/11 patients. Conclusions: γδ T cells exhibit an in vitro response to primary leukemia blasts that is manifested by proliferation, an increased proportion of Vδ1+ T cells, and cytotoxicity to the primary leukemia blasts. The Vδ1+ T cell population is also predominant in newly diagnosed leukemia patients likely due to a loss of circulating Vδ2+ T cells. A small proportion of newly diagnosed patients showed Vδ1 CDR3 region similarity. These findings suggest a role for γδ T cells in the immune response to leukemia.Paul F. Meeh and Michelle King are contributed equally to this work.     

Is the response of coral calcification to seawater acidification related to nutrient loading?

The effect of decreasing aragonite saturation state (Ω_Arag) of seawater (elevated pCO₂) on calcification rates of Acropora muricata was studied using nubbins prepared from parent colonies located at two sites of La Saline reef (La Réunion Island, western Indian Ocean): a back-reef site (BR) affected by nutrient-enriched groundwater discharge (mainly nitrate), and a reef flat site (RF) with low terrigenous inputs. Protein and chlorophyll a content of the nubbins, as well as zooxanthellae abundance, were lower at RF than BR. Nubbins were incubated at ~27°C over 2 h under sunlight, in filtered seawater manipulated to get differing initial pCO₂ (1,440–340 μatm), Ω_Arag (1.4–4.0), and dissolved inorganic carbon (DIC) concentrations (2,100–1,850 μmol kg⁻¹). Increasing DIC concentrations at constant total alkalinity (A_T) resulted in a decrease in Ω_Arag and an increase in pCO₂. A_T at the beginning of the incubations was kept at a natural level of 2,193 ± 6 μmol kg⁻¹ (mean ± SD). Net photosynthesis (NP) and calcification were calculated from changes in pH and A_T during the incubations. Calcification decrease in response to doubling pCO₂ relative to preindustrial level was 22% for RF nubbins. When normalized to surface area of the nubbins, (1) NP and calcification were higher at BR than RF, (2) NP increased in high pCO₂ treatments at BR compared to low pCO₂ treatments, and (3) calcification was not related to Ω_Arag at BR. When normalized to NP, calcification was linearly related to Ω_Arag at both sites, and the slopes of the relationships were not significantly different. The increase in NP at BR in the high pCO₂ treatments may have increased calcification and thus masked the negative effect of low Ω_Arag on calcification. Removing the effect of NP variations at BR showed that calcification declined in a similar manner with decreased Ω_Arag (increased pCO₂) whatever the nutrient loading.     

Who's on first in the cellular response to DNA damage?

Cellular DNA-repair pathways involve proteins that have roles in other DNA-metabolic processes, as well as those that are dedicated to damage removal. Several proteins, which have diverse functions and are not known to have roles in DNA repair, also associate with damaged DNA. These newly discovered interactions could either facilitate or hinder the recognition of DNA damage, and so they could have important effects on DNA repair and genetic integrity. The outcome for the cell, and ultimately for the organism, might depend on which proteins arrive first at sites of DNA damage.     

Immunodominance in the immune response to “multiple” histocompatibility antigens

Cytotoxic effector T cells putatively specific for multiple non-H-2 histocompatibility (H) antigens were generated by immunizing and boosting C57BL/6 and B6.C-H-2 ^dmice with BALB.B and BALB/c stimulator cells, respectively. The generated effectors were tested for cell-mediated lympholysis on a panel of targets whose BALB/c-derived non-H-2 H antigens were donated by CXB recombinant inbred mice. The spectrum of reactivity of cytotoxic effector T cells with CXB targets demonstrated that the effectors did not recognize multiple H antigens but rather preferentially recognized a single immunodominant non-H-2 H antigen. The identity of the immunodominant H antigen was determined by the H-2 genotype of the stimulator cells when (B6 × B6.C-H-2 ^d)F ₁ cytotoxic effectors were tested. These observations indicate that despite the fact that responders were challenged with more than 40 individual non-H-2 H antigens, they preferentially responded to a single immunodominant antigen.     

Role of Purα in the cellular response to ultraviolet-C radiation

Purα is a nucleic acid-binding protein with DNA-unwinding activity, which has recently been shown to have a role in the cellular response to DNA damage. We have investigated the function of Purα in Ultraviolet-C (UVC) radiation-induced DNA damage and nucleotide excision repair (NER). Mouse embryo fibroblasts from PURA^-/- knockout mice, which lack Purα, showed enhanced sensitivity to UVC irradiation as assessed by assays for cell viability and clonogenicity compared to Purα positive control cultures. In reporter plasmid reactivation assays to measure the removal of DNA adducts induced in vitro by UVC, the Purα-negative cells were less efficient in DNA damage repair. Purα-negative cells were also more sensitive to UVC-induced DNA damage measured by Comet assay and showed a decreased ability to remove UVC-induced cyclobutane pyrimidine dimers. In wild-type mouse fibroblasts, expression of Purα is induced following S-phase checkpoint activation by UVC in a similar manner to the NER factor TFIIH. Moreover, co-immunoprecipitation experiments showed that Purα physically associates with TFIIH. Thus, Purα has a role in NER and the repair of UVC-induced DNA damage.Key words: purα, ultraviolet radiation, DNA damage, DNA repair, nucleotide excision repair, TFIIH     

Quantitative measurements of activity ofAedes Aegypti (L.) (Culicidæ: Diptera) in response to changes in the hygrothermal environment

Reactions of A. AEGYPTI females to hygrothermal changes in the atmosphere were measured quantitatively by calculating the time between quantal cumulative response curves for take-off and settling. Reactions were compared among experimental groups derived from a stabilized colony and conditioned to a standard dark environment of 23 C and 100 per cent relative humidity.Atmospheric moisture was the limiting factor for duration of activity and for the initiation of the take-off or settling responses. Activity in response to hygrothermal conditions was mediated internally in relation to starvation and increased after a blood meal. Light operated interdependently with temperature and humidity to stimulate take-off after a period of rest.Activity appeared to be governed by the ability of mosquitoes to adapt to changes in the internal-external water balance.When the environmental water-vapor pressure remained near the adaptation level activity increased or decreased directly with temperature. Starving mosquitoes did not tolerate sudden decreases in water-vapor pressure, but did so within an hour following a blood meal. Large increases in watervapor pressure induced the resting state, which, if prolonged, took the form of prostrate immobilization. Maximum activity was related to the maximum hygrothermal change to which the mosquito could adapt without injury or without severe physiological consequences in water balance.

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Zusammenfassung Die Reaktionen von A. AEGYPTI Weibchen bei Änderungen der Temperatur und Feuchte in der AtmosphÄre wurden quantitativ durch die Reaktionskurven für Abflug und Aufsetzen gemessen. Die Reaktionen wurden mit denen von Mücken aus einer an Dunkelheit, 23 C und 100% R.F. adaptierten Standardkolonie verglichen. Der limitierende Faktor für die Dauer der AktivitÄt und für die Einleitung der Abflug und Landereaktion war die Feuchte. Bei der Änderung der Temperatur-Feuchte Bedingungen wurde die AktivitÄt durch Hunger beeinflusst und war nach einer Blutmahlzeit grosser. Licht stimulierte unabhÄngig von Temperatur und Feuchte den Abflug nach einer Ruheperiode. Die AktivitÄt der Mücken schien von der FÄhigkeit bestimmt zu werden, sich an Anderungen im intern-externen Wassergleichgewicht anzupassen.Wenn die Feuchte in der Höhe des Adaptationswertes lag, fiel oder stieg die AktivitÄt proportional zur Temperatur. Im Hunger konnten die Mücken einen plötzlichen Feuchteabfall nicht vertragen, wohl aber innerhalb einer Stunde nach einer Blutmahlzeit. Starker Anstieg der Feuchte leitete eine Ruhephase ein, die bei lÄngerem Bestehen zur EntkrÄftung führte. Maximale AktivitÄt war mit maximalen Temperatur-Feuchtewechsel verbundenen den die Mücken sich ohne ernste Folgen im Wasserhaushalt anpassen konnten.

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Resume La réaction de femelles d'A. AEGYPTI aux changements d'humidité et de température de l'atmosphère a été déterminée quantitativement au moyen des courbes de réaction fixant les intervalles de temps qui correspondent à l'envol et au retour. Les réactions ont été comparées à celles de moustiques appartenant à une colonie standard à l'obscurité, à 23 C de température et 100% d'humidité relative.L'humidité atmosphérique fut le facteur limitatif quant à la durée de l'activité et le déclenchement des réactions de repos et d'envol. L'activité en fonction des conditions d'humidité et de température fut influenÇable par la faim et montra un accroissement dans le cas de moustiques nourris de sang. Après une période de repos, une stimulation de l'envol eut lieu sous l'influence de la lumière, quelles que fussent les conditions de température et d'humidité.On constata que l'activité des moustiques fut dominée per leur faculté d'adaptation aux changements internes-externes de l'équilibre d'eau. Au cas où la pression de la vapeur d'eau environnante fut maintenue à proximité du niveau d'adaptation, l'activité augments ou décrût proportionellement à la température. A l'état affamé, les moustiques ne supportèrent pas les chutes rapides de la pression de la vapeur d'eau, mais, après qu'ils se fussent nourris de sang, le contraire eut lieu pendant une heure. Une forte augmentation de la pression de la vapeur d'eau provoqua le retour à l'état de repos, qui finit par prendre la forme d'un état d'épuisement. On constata que l'activité maximum correspond au changement maximum des conditions d'humidité et de température auquel les moustiques puissent s'adapter sans que soit porté préjudice à leur équilibre d'eau.

     

Does the white clover response to sulphur availability correspond to phenotypic or ontogenetic plasticity?

White clover (Trifolium repens L.) is a key species in grasslands. Its performance in grassland communities is strongly linked to nitrogen (N) availability. A decrease in soil sulphur (S) content has appeared in the last few decades in grasslands in Northern Europe and this could change the behaviour of white clover. S is essential for plants and particularly for legumes through its effect upon nitrogen fixation. The aim of this study was to determine the effects of S deficiency on white clover fitness, analysing its plasticity in a time course of growth.Three concentrations of SO₄^2?, “Low S” (0.009 mM), “Medium S” (0.384 mM) and “High S” (1.509 mM), were used to grow plants in a hydroponic system. S availability modified biomasses significantly only at the end of the experiment (11 weeks). Medium S appeared optimal while Low S induced a lower aboveground dry mass. An appropriate S availability (Medium S) not only increased S content but also increased N content by stimulating N₂ fixation. Plant growth analysis using growth fitted curves and the calculation of RGR revealed that S effects on biomass corresponded to the production of different phenotypes and not to a growth delay. This work shows that the acceleration growth phase (49–56 days) is a key period for the nutritional needs of white clover and should be the best period for a sulphur fertilisation regime that aims to enhance white clover fitness.