Choice of calibration equations in calibrating microwave test fixtures

The error theory of linear equation system has been applied to the calibration procedure of microwave network analyser in this article. A new explanation for the choice of the linear calibration equations is proposed and a general principle for choosing calibration equations is presented. The method can also be used to predict the occurrence of the problem of frequency limitation at some periodic frequencies. This principle is employed to the thru-short-delay (TSD) method and the solution using the chosen equations gives the most accurate results. A good agreement between the theory and the experiment has been obtained.

Effect of critical thickness on structural and optical properties of InxGa1-xN/GaN multiple quantum wells

InGaN/GaN multiquantum-well (MQW) structures grown by metalorganic chemical-vapor deposition on n-type GaN and capped by p-type GaN were investigated by cross-sectional transmission electron microscopy, double crystal x-ray diffraction, and temperature-dependent photoluminescence. For the sample with strained-layer thicknesses greater than the critical thicknesses, a high density of pure edge type threading dislocations generated from MQW layers and extended to the cap layer was observed. These dislocations result from a relaxation of the strained layers when their thicknesses are beyond the critical thicknesses. Because of indium outdiffusion from the well layers due to the anneal effect of Mg-doped cap layer growth and defects generated from strain relaxation, the PL emission peak was almost depressed by the broad yellow band with an intensity maximum at 2.28 eV. But for the sample with strained-layer thicknesses less than the critical thicknesses, it has no such phenomenon. The measured critical thicknesses are consistent with the calculated values using the model proposed by Fischer, Kuhne, and Richter. (C) 2004 American Institute of Physics.

OLAND生物脱氮系统运行条件及其微生物群落结构的研究

OLAND两阶段生物脱氮系统是一项正在开发且极具应用前景的处理高氨氮、低COD废水的新技术。在实验室水平，对OLAND系统限氧亚硝化阶段MBR反应器和厌氧氨氧化阶段SBR反应器的启动和运行进行了系统研究。MBR反应器控制参数在DO0.1-0.3mg/L，pH7.8±0.1，温度30±0.5℃，SRT无穷大的条件下，可实现在较高的容积负荷By＝IO00mgN／L，水力停留时间HRT：ld下稳定的亚硝酸型硝化，使NH4+-N和NO2-N的出水比例达到理想的比值（1:1.20±0.20），保证厌氧氨氧化阶段SBR反应器的理想进水；SBR反应器在完全厌氧、pH7.8-8.2，温度30±0．5℃，SRT无穷大的条件下，无需外加任何有机碳源，在较高总氮负荷550mgN／L下，可实现NH4+-N和NO2--N同时稳定的去除，二者的消耗比例为1:（1.21±0.05），总氮去除率高达92％。采用巢式PCR、DGGE、 FISH等分子技术对MBR反应器硝化菌群随溶解氧的动态变化规律和SBR反应器厌氧氨氧化菌群结构、组成进行了研究，并探讨了硝化菌群与氮素组成变化之间的内在联系。结果表明：在限氧亚硝化阶段硝化菌群中氨氧化菌受溶解氧浓度的影响较大，其种群结构从反应器启动初期到稳定后期发生了非常明显的变化。亚硝酸氧化菌NOB的种群组成受溶氧影响并不明显，从启动初期到稳定后期其种群结构无明显变化。硝化菌群中氨氧化菌 AOB与亚硝酸氧化菌NOB的数量比例关系随溶解氧的降低而不断升高，从最初的3.6:1升高到稳定后期的5.5:1。MBR反应器优势硝化菌群主要由A、B、C三类氨氧化菌和硝化杆菌D、硝化螺菌F组成，其中优势菌C为维持MBR反应器稳定出水比例的主要功能菌。硝化菌群组成和结构的变化，带来了不同N素之间组成和比例的规律性变化。厌氧氨氧化阶段基本由厌氧氨氧化菌AnAOB和ANAMMOX两类菌组成，二者空间结构紧密，在反应器中的活菌数量比例分别为55％和42％。厌氧氨氧化菌AnAOB种群多样性相对比较丰富，主要由条带I和H所代表的两种优势菌组成；ANAMMOX菌种群多样性变化较小，其种群主要由优势菌K和J组成。对MBR和SBR反应器中的优势菌进行了克隆、测序和系统发育学分析，结果表明：限氧亚硝化阶段MBR反应器启动初期的优势菌A属于Nitrosomonadaceae科，是否是一个新属，还有待于进一步鉴定。运行中期优势菌B与Nitroso）nonaseurooaea亲缘关系最近，同源性高达99.1％，暂命名为Nilrosomonas sp.BI。稳定后期优势菌C与Nitrosomonas eutroPha亲缘关系最近，同源性为96.3％，暂命名为Nifrosomonas sp．cl。硝化杆菌属优势菌D与Nitrobacter alkalicus、Nitrobacter hambllrgensts和Nitlobac招rwinograsky 亲缘关系较近，同源性分别为95.5-97％、96.5～97％和95.8～96.8％。SBR反应器中AnAOB优势菌I与MBR反应器优势菌B亲缘关系最近，同源性高达98.7％，与Nitlosomonas euroPaea同源性为98.3％。根据序列比较和生理特性分析，优势菌I与优势菌B应为Nitrosomonas属两个不同的种，暂将优势菌I命名为Nitrosomonas sp．II。优势菌H与MBR反应器优势菌C亲缘关系最近，同源性达97.9％，与Nitrosomonas eutropha同源性为96.3％。结合其生理特性分析，二者应为Nitrosomonas属两个不同的种，暂将优势菌H命名为Nitrosomollas sp．Hl。ANAMMox优势菌K与未培养的 Planctomycete和已鉴定的另一种ANAMMoX菌尤uenenia sf况ttgartiensis亲缘关系较近，同源性分别为99.8％和96.6％。优势菌J与Gen bank收录的所有菌的相似性均低于76％，说明该菌是OLAND系统厌氧氨氧化阶段比较独特的菌，是迄今为止在厌氧反应过程中未发现的一个新菌。

复合潜流人工湿地处理城市地表径流研究

以武汉市桃花岛塘和复合潜流人工湿地组合生态处理系统为研究对象,考察了对城市地表径流的处理效果。结果表明,塘和复合潜流人工湿地组合生态系统可以有效净化城市地表径流,对各污染物的去除率:COD为84.0%~85.4%、TP为89.6%~91.8%、TN为92.2%~94.4%、SS为95.8%~97.1%,其中复合潜流人工湿地对COD、TP、TN、SS的去除率分别为69.0%~73.1%、82.6%~86.6%、89.0%~90.4%、64.7%~69.2%,除氮效果独特。在无雨期该生态系统可用于净化湖水,实现了削减污染和保持系统稳定的双重功能,同时还可补给养鱼塘用水。

Artificial neural network classification based on high-performance liquid chromatography of urinary and serum nucleosides for the clinical diagnosis of cancer

Nucleosides in human urine and serum have frequently been studied as a possible biomedical marker for cancer, acquired immune deficiency syndrome (AIDS) and the whole-body turnover of RNAs. Fifteen normal and modified nucleosides were determined in 69 urine and 42 serum samples using high-performance liquid chromatography (HPLC). Artificial neural networks have been used as a powerful pattern recognition tool to distinguish cancer patients from healthy persons. The recognition rate for the training set reached 100%. In the validating set, 95.8 and 92.9% of people were correctly classified into cancer patients and healthy persons when urine and serum were used as the sample for measuring the nucleosides. The results show that the artificial neural network technique is better than principal component analysis for the classification of healthy persons and cancer patients based on nucleoside data. (C) 2002 Elsevier Science B.V. All rights reserved.

Classification of valence changes of trivalent rare earth ions in alkaline earth borates using artificial neural networks

The investigations of classification on the valence changes from RE3+ to RE2+ (RE = Eu, Sm, Yb, Tm) in host compounds of alkaline earth berate were performed using artificial neural networks (ANNs). For comparison, the common methods of pattern recognition, such as SIMCA, KNN, Fisher discriminant analysis and stepwise discriminant analysis were adopted. A learning set consisting of 24 host compounds and a test set consisting of 12 host compounds were characterized by eight crystal structure parameters. These parameters were reduced from 8 to 4 by leaps and bounds algorithm. The recognition rates from 87.5 to 95.8% and prediction capabilities from 75.0 to 91.7% were obtained. The results provided by ANN method were better than that achieved by the other four methods. (C) 1999 Elsevier Science B.V. All rights reserved.

真鲷(Pagrosomus major)胚胎冷冻保存损伤机理及冷冻精子遗传物质稳定性研究

本文对真鲷心跳期胚胎对5种常用渗透性抗冻剂（DMSO、甘油、甲醇、丙二醇、乙二醇）和3种非渗透性抗冻剂（PVP、PEG-8000、蔗糖）的耐受性进行了研究。渗透性抗冻剂分6个浓度梯度（5%；10%；15%；20%；25%；30%）和3个时间组（10min；30min；1h）。非渗透性抗冻剂中，PVP、PEG-8000分3个浓度梯度（5%、10%、15%）和2个时间组（10min、30min），蔗糖为4个浓度梯度（5%、10%、15%、20%）和2个时间组（10min、30min）。实验结果表明，在渗透性抗冻剂组中，浓度为5%的处理组的孵化率（>90%）与对照组差异均不显著，随着抗冻剂浓度增大及处理时间的延长，真鲷心跳期胚胎的孵化率显著下降（P<0.05），在最高浓度的最长处理时间中胚胎孵化率均降到了0。总体上，真鲷心跳期胚胎对五种渗透性抗冻剂的耐受性从小到大依次为：甲醇 < 甘油 < 乙二醇 < DMSO < 丙二醇。对影响胚胎孵化率的三个因素（抗冻剂、浓度、时间）进行的因素效应分析结果表明，三种因素对孵化率的影响显著（P<0.05），并且浓度效应 > 时间效应 > 抗冻剂效应。在非渗透性抗冻剂组中，蔗糖组胚胎孵化率未呈显著变化；PVP组随着浓度及时间的增大，孵化率显著下降（P<0.05）；PEG-8000组随着浓度增大孵化率显著下降（P<0.05），但在两个时间组间差异不显著。相同处理情况下PEG-8000对真鲷心跳期胚胎的毒性要小于PVP。因素效应分析比较结果表明仅时间效应不显著，且抗冻剂效应 > 浓度效应 > 时间效应。 对所用各种抗冻剂进行了渗透压测量，实验中使用的渗透性抗冻剂（5%-30%）的渗透压值在959-7980mOsm/kg之间，均高于使用海水的渗透压值（919mOsm/kg）；使用的非渗透性抗冻剂的渗透压值在316-1040mOsm/kg之间，除20%蔗糖渗透压值（1040mOsm/kg）高于海水外，其他非渗透性抗冻剂的渗透压值均要低于海水。对孵化率与相应的溶液渗透压值进行相关回归分析结果表明，渗透性抗冻剂的渗透压与孵化率呈显著的负相关（P<0.05），而非渗透性抗冻剂的渗透压与孵化率相关不显著。渗透性抗冻剂组的回归分析结果表明，二次方程的曲线拟合度最高，得到的回归方程分别为：Y10min = -2×10-8X2 10min - 6×10-5 X 10min + 1.5635 （R2 = 0.713），Y30min= 5×10-8X2 30min－0.0007 X 30min + 2.097（R2 = 0.681），Y1h = 7×10-8X2 1h－0.0008 X 1h+ 2.0397（R2= 0.725）。 在真鲷胚胎对抗冻剂耐受性实验的基础上，挑选五种抗冻剂--10%DMSO、5%甘油、10%甲醇、20%丙二醇、10%乙二醇，浸泡真鲷心跳期胚胎30min后，分别以超速（130℃/min）、快速（20℃/min）、慢速（3℃/min）的速度降温并使用低温显微镜进行观察，依次记录Toif（油球结冰）、Teif（胚胎外部结冰）、Tiif（胚胎内部结冰）等结冰点，Toif值在-9~-23℃之间；Teif值在-21~-35℃之间；Tiif值在-21~-52℃之间。结冰顺序为先油球结冰，然后胚胎外部结冰随之内部马上瞬间变黑形成内部冰晶。随着降温速度的提高，各结冰温度值显著下降。各抗冻剂之间的Teif及Tiif值不同，Toif值之间没有显著差异。对两种玻璃化冷冻方法进行模拟观察，发现胚胎冰晶形成的顺序与非玻璃化过程不同--先内部结冰然后逐渐蔓延至外部形成外部冰晶，而且模拟玻璃化的内部结冰温度Tiif值（-52.56℃）显著（P<0.05）低于使用低浓度的同种抗冻剂超速降温组的Tiif值（-40.11℃）。在快速及慢速降温组中，20%丙二醇组的Tiif要显著的低于其他组（P<0.05）；在超速降温中，甲醇组的Tiif值要显著的低于其他组（P<0.05）。在Tiif小于30℃的实验组中获得形态完整胚胎的比例平均仅有30.77%；在Tiif大于30℃的实验组中获得形态完整胚胎的平均比例高达70.37%，模拟玻璃化组达到100%。各抗冻剂之间，复温后胚胎形态完整率10%甲醇组最高（77.78%）；其次依次为10%乙二醇（66.67%）、20%丙二醇（55.56%）和10%DMSO（55.56%）；5%甘油组最低（11.11%）；推测甲醇的对胚胎的渗透效果要好于其他组。综上推测：使用丙二醇、甲醇作为抗冻剂以及玻璃化冷冻保存方法对真鲷心跳期胚胎超低温保存也许较为合适。 我们对低温保存的真鲷精子核DNA损伤进行了研究以期为下一步胚胎遗传物质稳定性研究提供参考依据。研究方法为单细胞凝胶电泳（SCGE），针对研究对象，在实验过程中对传统的碱性单细胞凝胶电泳在铺胶方法、电泳条件等进行了改进。对精子细胞进行预处理，在碱性电泳液中使核DNA双链解链变性后电泳，EB染色lOmin后，在荧光显微镜下观察，每次随机观察50个左右的核DNA。结果表明，对荧光显微镜下观察到的精子核按彗尾长度及荧光强度划分等级，出现损伤的精子核DNA的损伤程度主要为轻度损伤和中度损伤，很少见有完全损伤的真鲷精子核。经5%、10%、18%、20%、25%、30%DMSO冷冻保存后的精子彗星率分别为33.47％ ± 8.95％; 35.91％ ± 19.44％; 48.95％ ± 8.90％; 43.33％ ± 11.19％; 55.80％ ± 38.94％。鲜精彗星率为31.43 ％ ± 2.68％。对比真鲷冷冻精液与新鲜精液的精子DNA的损伤状况，表明仅用30％ DMSO冷冻精子DNA损伤状况与鲜精差异显著(P<0.05)。 综上所述，渗透性抗冻剂对胚胎的毒性与其渗透压值呈显著的负相关关系。丙二醇对真鲷心跳期胚胎毒性最小，甲醇较其他抗冻剂能更好的渗透入胚胎；玻璃化方法能显著降低Tiif值并能更好的保持超低温保存后胚胎的形态完整性，因此，使用丙二醇、甲醇作为抗冻剂以及玻璃化冷冻保存方法对真鲷心跳期胚胎超低温保存也许较为合适。常规使用的用于超低温保存真鲷精子的DMSO（浓度<15%）不会对精子核物质稳定性造成明显影响。由于胚胎较精子结构要复杂许多，对于真鲷胚胎损伤机理的研究还有大量工作可以开展。

Flow cytometry and ultrastructure of cryopreserved red seabream (Pagrus major) sperm

The objectives were to assess motility, fertilizing capacity, structural integrity, and mitochondrial function in fresh versus frozen-thawed (15% DMSO was used as a cryoprotectant) sperm from red seabrearn (Pagrus major). Mean (+/- S.D.) rates of motility, fertilization and hatching of frozen-thawed sperm were 81.0 +/- 5.4, 92.8 +/- 1.9, and 91.8 +/- 5.2%, respectively; for fresh sperm, they were 87.5 +/- 7.7, 95.8 +/- 2.4, and 93.8 +/- 4.2%. Although motility was lower in frozen-thawed versus fresh sperm (P < 0.05), there was no effect (P > 0.05) of cryopreservation on fertilization or hatching. Based on scanning and transmission electron microscopy, 77.8 +/- 5.6% of fresh sperm had normal morphology, whereas for frozen-thawed sperm, 63.0 +/- 7.2% had normal morphology, 20.6 +/- 3.1% were slightly damaged (e.g. swelling or rupture of head, mid-piece and tail region as well as mitochondria), and 16.4 +/- 4.2% were severely damaged. Sperm were stained with propidium iodide and Rhodamine 123 to assess plasma membrane integrity and mitochondrial function, respectively, and examined with flow cytometry. For fresh sperm, 83.9% had an intact membrane and functional mitochondria, whereas for frozen-thawed sperm, 74.8% had an intact membrane and functional mitochondria, 12.7% had a damaged membrane, 9.9% had nonfunctional mitochondria, and 2.6% had both a damaged membrane and nonfunctional mitochondria. In conclusion, ultrastructure and flow cytometry were valuable for assessment of frozen-thawed sperm quality; cryopreservation damaged the sperm but fertilizing ability was not significantly decreased. (c) 2007 Elsevier Inc. All rights reserved.

甘肃胡麻地方种质资源品质特性研究

对甘肃省116份胡麻地方品种的重要品质指标--粗脂肪、硬脂酸、棕榈酸、油酸、亚油酸、亚麻酸含量和碘值进行测定,并根据这些品质指标对供试品种进行聚类分析.结果显示:(1)供试品种粗脂肪含量平均值为37.48%,变异系数3.8%;硬脂酸、油酸含量平均值分别为5.32%和29.05%,变异系数分别为19.5%和11.6%;棕榈酸、亚麻酸、亚油酸含量平均值分别为5.9%、48.76%、10.95%,变异系数分别为8.4%、8%、8%;平均碘价175.60,变异系数2.76%;(2)聚类分析结果显示,116个品种聚为7大类,其中:b亚组群硬脂酸和油酸含量最高,而亚麻酸含量最低;d亚组群品种亚麻酸含量最高;e亚组群粗脂肪含量和碘价最高,油酸含量最低;f亚组群硬脂酸含量最低;g亚组群棕榈酸含量最高,碘价最低.

Tuberous sclerosis complex: clinical features, diagnosis, and prevalence within Northern Ireland

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in the TSC1 and TSC2 genes on chromosomes 9 and 16 respectively. Diagnosis is based on clinical features but can be difficult as a result of variable phenotypic expression. With the advantage of mutation analysis in making a diagnosis of TSC, and improved identification of the associated clinical features, there have been few new data on its prevalence and on the proportion of cases due to new mutations. We have performed a retrospective epidemiological study on the prevalence of TSC, the clinical features attributed to it, and the availability of mutational analysis. We identified 73 known patients with TSC (5 deceased): 39 were female and 34 male. Ages ranged from 10 months to 69 years, with a mean age of 27 years 11 months (SD 16y 10mo). The point prevalence of TSC in our study was estimated at I out of 24 956 on the prevalence day (30 April 2004). The majority of patients (42.5%) were diagnosed at less than 15 months of age; 25% were not given a diagnosis on first developing symptoms. In all, 93.2% had epilepsy and 71.2% had a learning disability.* A mutation was identified in 95.8% of those tested (26% TSC1 and 74% TSC2). TSC2 mutations were correlated with a more severe phenotype. The new mutation rate was calculated at 64%. We conclude that the prevalence of TSC is higher than previously calculated. We recommend that all children with epilepsy be assessed for features of TSC. Larger studies will be required to assess the prevalence of mutations in each gene, and genotype-phenotype correlation.

Motor skill deficits in children with partial hearing

AIM:
We examined the effect of partial hearing, including cochlear implantation, on the development of motor skills in children (aged 6-12y).

METHOD:
Three independent groups of children were selected: a partial hearing group (n=25 [14 males, 11 females]; mean age 8y 8mo, SD 1y 10mo), a nonverbal IQ-matched group (n=27 [15 males, 12 females]; mean age 9y, SD 1y 6mo), and an age-matched group (n=26 [8 males, 18 females]; mean age 8y 8mo, SD 1y 7mo) from three schools with special units for children with partial hearing. All children with partial hearing had a bilateral hearing loss >60 decibels. Motor and balance skills were assessed using the Movement Assessment Battery for Children (MABC) and two protocols from the NeuroCom Balance Master clinical procedures.

RESULTS:
The mean standardized total MABC score of the children with partial hearing (95% confidence interval [CI] 71.8-88.7) was significantly lower than both the age-matched (95% CI 95.8-111.4; p<0.01) and the IQ-matched (95% CI 87.6-103.0; p=0.03) comparison groups. The children with partial hearing had particular difficulties with balance, most notably during tests of intersensory demand. However, subgroup analyses revealed that the effect of cochlear implantation was clearly dependent on the nature of the task.

INTERPRETATION:
Children with partial hearing are at high risk of clinical levels of motor deficit, with balance difficulties providing support for conventional vestibular deficit theory. However, the effect of cochlear implantation suggests that other sensory systems may be involved. A broader ecological perspective, which takes into account factors external to the child, may prove a useful framework for future research.

A comparative study of qualitative immunochemical screening assays for the combined measurement of T-2/HT-2 in cereals and cereal-based products

Many different immunochemical platforms exist for the screening of naturally occurring contaminants in food from the low cost enzyme linked immunosorbent assays (ELISA) to the expensive instruments such as optical biosensors based on the phenomenon of surface plasmon resonance (SPR). The primary aim of this study was to evaluate and compare a number of these platforms to assess their accuracy and precision when applied to naturally contaminated samples containing HT-2/T-2 mycotoxins. Other important factors considered were the speed of analysis, ease of use (sample preparation techniques and use of the equipment) and ultimately the cost implications. The three screening procedures compared included an SPR biosensor assay, a commercially available ELISA and an enzyme-linked immunomagnetic electrochemical array (ELIME array). The qualitative data for all methods demonstrated very good overall agreements with each other, however on comparison with mass spectrometry confirmatory results, the ELISA and SPR assay performed slightly better than the ELIME array, exhibiting an overall agreement of 95.8% compared to 91.7%. Currently, SPR is more costly than the other two platforms and can only be used in the laboratory whereas in theory both the ELISA and ELIME array are portable and can be used in the field, but ultimately this is dependent on the sample preparation techniques employed. Sample preparative techniques varied for all methods evaluated, the ELISA was the most simple to perform followed by that of the SPR method. The ELIME array involved an additional clean-up step thereby increasing both the time and cost of analysis. Therefore in the current format, field use would not be an option for the ELIME array. In relation to speed of analysis, the ELISA outperformed the other methods.

Change in the use of and attitude to peak flow measurement among general practitioners in Northern Ireland between 1989 and 1994

In 1994 we repeated a study first performed in 1989 to assess the change in general practitioners' use of and attitudes to peak flow measurement. Of 232 general practitioners surveyed, 199 (86%) and 192 (83%) responded in 1989 and 1994 respectively. The percentage who reported having patients using domiciliary peak flow monitoring rose form 58.3 (95% confidence limits 51.4 to 65.2)% to 97.9 (95.9 to 99.9)%. The percentage who reported 'usually' using peak flow measurements for the diagnosis and management of asthma rose from 81.9 (76.5 to 87.3)% to 93.2 (89.6 to 96.8)% and from 83.3 (78.1 to 88.5)% to 95.8 (92.9 to 98.7)% respectively. An unchanged proportion took peak flow meters on house calls. General practitioners have become more aware of the potential of peak flow measurements but are still unlikely to have a meter available to assess patients seen at home. They are therefore likely to be ill-equipped to manage acute exacerbations of asthma in this setting.

Human mesenchymal stem cells reduce the severity of acute lung injury in a sheep model of bacterial pneumonia

Background Human bone marrow-derived mesenchymal stem (stromal) cells (hMSCs) improve survival in mouse models of acute respiratory distress syndrome (ARDS) and reduce pulmonary oedema in a perfused human lung preparation injured with Escherichia coli bacteria. We hypothesised that clinical grade hMSCs would reduce the severity of acute lung injury (ALI) and would be safe in a sheep model of ARDS.

Methods Adult sheep (30–40 kg) were surgically prepared. After 5 days of recovery, ALI was induced with cotton smoke insufflation, followed by instillation of live Pseudomonas aeruginosa (2.5×10¹¹ CFU) into both lungs under isoflurane anaesthesia. Following the injury, sheep were ventilated, resuscitated with lactated Ringer's solution and studied for 24 h. The sheep were randomly allocated to receive one of the following treatments intravenously over 1 h in one of the following groups: (1) control, PlasmaLyte A, n=8; (2) lower dose hMSCs, 5×10⁶ hMSCs/kg, n=7; and (3) higher-dose hMSCs, 10×10⁶ hMSCs/kg, n=4.

Results By 24 h, the PaO₂/FiO₂ ratio was significantly improved in both hMSC treatment groups compared with the control group (control group: PaO₂/FiO₂ of 97±15 mm Hg; lower dose: 288±55 mm Hg (p=0.003); higher dose: 327±2 mm Hg (p=0.003)). The median lung water content was lower in the higher-dose hMSC-treated group compared with the control group (higher dose: 5.0 g wet/g dry [IQR 4.9–5.8] vs control: 6.7 g wet/g dry [IQR 6.4–7.5] (p=0.01)). The hMSCs had no adverse effects.

Conclusions Human MSCs were well tolerated and improved oxygenation and decreased pulmonary oedema in a sheep model of severe ARDS.

Déterminants des choix alimentaires d'athlètes adolescents en période de compétition

Cette étude s’insère dans une étude s’intitulant « Choix alimentaires d’adolescents canadiens et attitudes de leurs entraîneurs impliqués dans des activités sportives organisées ». Les objectifs étaient d’étudier chez des adolescents impliqués dans une compétition sportive provinciale où l’offre alimentaire est contrôlée 1) leur maîtrise des recommandations nutritionnelles 2) les facteurs individuels, comportementaux, socio-environnementaux influençant leurs choix alimentaires. Deux observateurs ont visité les différents sites alimentaires et de compétition pendant les Jeux du Québec de 2011 à Valleyfield. Les plateaux des athlètes ont été photographiés à table au moment des repas avec une caméra numérique et les commentaires oraux colligés par écrit. Au total, 173 photographies ont été analysées et comparées aux recommandations reconnues en nutrition sportive. Dans notre étude, les préférences alimentaires, l’offre alimentaire et la présence des coéquipiers sont les facteurs qui influencent le plus les choix alimentaires en compétition. Par contre, le sexe de l’athlète n’a pas influencé les choix alimentaires des athlètes observés. En pré-compétition, 85,4% des plateaux présentent une valeur énergétique supérieure aux recommandations et 66,3% d’entre eux ont une répartition en énergie inadéquate, peu importe le sexe. Un excès de lipides et de protéines au sein du repas précédant l’effort caractérise majoritairement les plateaux dont la répartition en énergie est non optimale (69,5%). Les recommandations en post-compétition (100%) et lors des jours de repos (95,8%) ont facilement été rencontrées. Il en est de même pour l’hydratation (99,4%). Le lait au chocolat est la boisson la plus populaire (59,5%). Les produits céréaliers (99,4%), le lait et substituts (87,3%), les légumes (85,7%), les viandes et substituts (83,2%), les aliments riches en sucres (79,8%), les fruits (70,5%) et les mets riches en gras (59,4%) sont particulièrement appréciés par les athlètes. Les commentaires recueillis font ressortir une vision dichotomique des aliments chez certains athlètes qui classifient les aliments en « bons » ou « mauvais ». Notre étude démontre que la présence d’une politique alimentaire permet de promouvoir des habitudes alimentaires saines et favorise la consommation d’aliments nutritifs lors d’une compétition sportive d’envergure. Cependant, de l’éducation en nutrition est toujours requise pour viser l’amélioration du comportement alimentaire avant l’effort.