烟草次生物质──烟碱对烟蚜影响的研究

采用田间调查和室内饲养的方法，结合化验分析结果，分析了烟草次生物质烟碱对烟蚜的影响。结果表明烟叶中烟碱的含量非常明显的影响着烟蚜在田间的种群数量，烟碱浓度与烟蚜数量呈明显的负相关性。全纯人工饲料饲养结果表明，烟碱的浓度不仅影响烟蚜的存活率，对烟蚜的胎生期、胎生量及存活时间也存在着明显的影响，饲料中烟碱浓度10×10-6以下时，对烟蚜的胎生期及胎生量基本没有影响，超过20×10-6就会产生明显的负作用。且随着烟碱浓度的提高，负作用明显加强。     

温度对大豆食心虫卵和幼虫生长发育的影响

在17～33℃条件下,研究了温度对大豆食心虫卵和幼虫生长发育的影响。结果表明：在试验温度范围内,卵的发育速率与温度呈正相关,模型为：Yegg=0.61/[1＋exp（3.19-0.08t）]（F=128.5976,p=0.0077,R=0.9961）,发育历期随温度升高而缩短;幼虫期发育速率模型为：Ylarva=0.10/[1＋exp（3.25-0.17t）]（F=21.7316,p=0.0440,R=0.9778）,其中2龄、3龄幼虫发育速率与温度呈正相关且明显高于其它龄期,33℃条件对1龄和4龄、5龄幼虫的生长发育有抑制作用。温度对大豆食心虫卵孵化率影响不明显,而对各龄幼虫存活率的影响较大,幼虫期对环境温度的适应性随龄期增加而增强。温度影响幼虫的营养积累,在25℃条件下老熟幼虫体重为17.26mg,显著高于其它温度。大豆食心虫卵的发育起点温度为7.24℃,有效积温为117.63d.℃;幼虫期发育起点温度为4.71℃,有效积温为285.33d.℃。     

A new environmental heat stress index for indoor hot and humid environments based on Cox regression

Physical work in hot and humid environments imposes health risks, productivity falling and safety problems on workers. Protection of workers from heat related problems requires quantitative heat stress assessment of the workplace. In this paper, a new index-equivalent temperature (ET) is proposed to measure the environmental heat stress in indoor hot and humid environments. A climate chamber was built to simulate the indoor hot and humid environment. And the safe working time of 144 male volunteers were studied under different climatic conditions in the chamber. Cox regression method is adopted to obtain the impacts of variables on the safe working time. Then the new index-ET is proposed based on the Cox regression results. The correlations between the ET and the common used indexes are determined to test the validity of this new index. Finally the safe working time concerned with the ET is summarized. The results show that the new index gives physiological correlates and physical means. The ET developed in this paper has the potential to be a practical index to measure the environmental heat stress in indoor hot and humid environments.     

Drying kinetics and survival studies of dairy fermentation bacteria in convective air drying environment using single droplet drying

The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45–95 °C) at a constant air velocity (0.5 m/s) and within 2.4–11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (?65 °C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (?55 °C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3 kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8 kJ/mol) within the medium temperature of 45–95 °C.     

Population dynamics of Escherichia coli inoculated by irrigation into the phyllosphere of spinach grown under commercial production conditions

Recent outbreaks of food-borne illnesses associated with the consumption of fresh produce have increased attention on irrigation water as a potential source of pathogen contamination. A better understanding of the behaviour of enteric pathogens introduced into agricultural systems during irrigation will aid in risk assessments and support the development of appropriate farm-level water management practices. For this reason, the survival dynamics of two nalidixic acid resistant strains of Escherichia coli after their spray inoculation into the phyllosphere and soil of field spinach were examined over two growing seasons. E. coli strains NAR, an environmental isolate, and DM3n, a non-pathogenic serotype O157:H7, were applied at rates of 10⁴ to 10⁷ cfu/100 ml to the fully developed spinach plants that arose subsequent to the harvesting of their upper leafy portions for commercial purposes (secondary-growth plants). After 72 h, E. coli on spinach were reduced by 3-5 logs. Culturable E. coli were recovered from plants up to 6 days post-inoculation. Survival in soil was greater than in the phyllosphere. Under ambient conditions, the mean 72 h first order decay constant computed by Chick's Law was 0.1 h⁻¹. Although light reduction studies indicated UV irradiation negatively influenced the persistence of E. coli, a simple relationship between UV exposure and phyllosphere E. coli densities could not be established. E. coli introduced to the leafy portions of spinach via spray irrigation displayed rapid declines in their culturability under the open environmental conditions experienced during this study. A 6 day period between the last irrigation and harvest would minimize the risks of E. coli survival in the spinach phyllosphere. E. coli NAR was identified as a possible surrogate for the O157:H7 strain, DM3n.     

Survival of Lactobacillus acidophilus, Lactobacillus paracasei subsp. paracasei, Lactobacillus rhamnosus, Bifidobacterium animalis and Propionibacterium in cheese-based dips and the suitability of dips as effective carriers of probiotic bacteria

The suitability of cheese-based dips as a delivery vehicle for probiotic bacteria including Lactobacillus acidophilus, Lactobacillus paracasei subsp. paracasei, Lactobacillus rhamnosus, Bifidobacterium animalis, and Propionibacterium freudenreichii subsp. shermanii was studied by evaluating the survival of these organisms in dips. Effects of organic acids, oils and gums, -cysteine and NaHCO₃ on the survival of probiotics in cheese-based dips were also studied. Eight different combinations and five individual bacteria as controls of these probiotic bacteria were added to 21 batches of French onion dip and selective enumeration of these probiotic bacteria was carried out over a period of 10 weeks of storage. The population of L. acidophilus and B. animalis reduced by 1 log and 2 log per g, respectively. However, when the inoculation level of these bacteria were increased to 8 log per g, they maintained a population of more than 6 log over the shelf life. L. paracasei subsp. paracasei and L. rhamnosus remained at the inoculated level or increased slightly during the storage. A rapid increase in the population of P. freudenreichii subsp. shermanii occurred to attain more than the inoculation level following reduction in their number by 3 log. Except bacterial interaction, no other factors showed significant effect on the survival of individual probiotic bacteria. Each of L. acidophilus, B. animalis, L. paracasei subsp. paracasei, and L. rhamnosus showed varied levels of antogonism, while P. freudenreichii subsp. shermanii showed no effect. Any combination of these bacteria can be used as probiotics in cheese-based French onion dip. However, the inoculation level should be 8 log per g for L. acidophilus and B. animalis and 7 log per g for L. paracasei subsp. paracasei, and/or L. rhamnosus to obtain greater than 6 log of individual bacterial population at the end of shelf life.     

~(60)Coγ射线照射对中国仓鼠肺细胞某些生物学指标的影响

本文介绍中国仓鼠肺(CHL)细胞受0.087—10.0Gy 剂量~(60)Coγ射线照射后,细胞群体倍增数、存活率、染色体畸变率和超微结构的变化等观察结果。~(60)Co γ射线诱发的 CHL 细胞染色体畸变中,双着十环的畸变率Y(%)与剂量 D(Gy)的关系可用 y=4.26×10~(-2)D+4.43×10~(-3)D~2表示。CHL 细胞的50%生长抑制剂量为4.0Gy。1.0—10.0Gy 剂量组细胞的超微结构可见线粒体肿胀和空泡化,3.0Gy 组核膜凹陷,5.0Gy 以上剂量组有的细胞核质疏松、核膜多处深陷和核仁消失。扫描电镜观察,1.0和3.0Gy 剂量组细胞表面的皱褶和绒毛减少或消退。     

SPP1 and the risk score model to improve the survival prediction of patients with hepatocellular carcinoma based on multiple algorithms and back propagation neural networks

Hepatocellular carcinoma (HCC) is associated with poor prognosis and fluctuations in immune status. Although studies have found that secreted phosphoprotein 1 (SPP1) is involved in HCC progression, its independent prognostic value and immune-mediated role remain unclear. Using The Cancer Genome Atlas and Gene Expression Omnibus data, we found that low expression of SPP1 is significantly associated with improved survival of HCC patients and that SPP1 expression is correlated with clinical characteristics. Univariate and multivariate Cox regression confirmed that SPP1 is an independent prognostic factor of HCC. Subsequently, we found that T cell CD4 memory-activated monocytes, M0 macrophages, and resting mast cells showed significant differences in penetration in the high and low SPP1 expression groups. Next, we used the Weighted Gene Co-Expression Network and Least Absolute Shrinkage Sum Selection Operator algorithms to construct a risk score for the 9-immune-related genes signature. The risk score showed a good ability to identify high and low-risk patients and improved survival prediction. We also used multivariate Cox regression to validate that risk score was significantly correlated with SPP1 and overall survival. Lastly, the Back-Propagation Neural Network confirmed the reliability of the results of multiple algorithms. In conclusion, the findings suggest that SPP1 is an independent marker of HCC survival and immunotherapy.     

Riskformer: Survival prediction from MR imaging in patients with IDH-wildtype glioblastoma

BackgroundGlioblastoma is the most common malignant brain tumor in adults. Despite aggressive treatment, its prognosis is still poor, with a median overall survival of less than 15 months.MethodsIn this study, we developed and validated a vision transformer-based model, named Riskformer, built from preoperative MRI for predicting OS in patients with newly diagnosed IDH-wildtype glioblastoma patients.ResultsRiskformer score was associated with OS as an independent prognostic factor in patients with IDH-wildtype glioblastoma. In the training dataset (hazard ratio [HR]: 5.930, 95% confidence interval [CI]: 3.933–8.942, P < 0.001), validation dataset (HR: 2.436, 95% CI: 1.334–4.447, P < 0.001) and testing dataset (HR: 4.651, 95% CI: 2.233–9.688, P < 0.001).ConclusionThe Riskformer score could provide independent and incremental prognostic value over existing clinical factors in OS prediction in patients with IDH-wildtype glioblastoma.