Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.     

Use of Pentamidine As Secondary Prophylaxis to Prevent Visceral Leishmaniasis Relapse in HIV Infected Patients,the First Twelve Months of a Prospective Cohort Study

Background

Visceral leishmaniasis (VL) has become an important opportunistic infection in persons with HIV-infection in VL-endemic areas. The co-infection leads to profound immunosuppression and high rate of annual VL recurrence. This study assessed the effectiveness, safety and feasibility of monthly pentamidine infusions to prevent recurrence of VL in HIV co-infected patients.

Methods

A single-arm, open-label trial was conducted at two leishmaniasis treatment centers in northwest Ethiopia. HIV-infected patients with a VL episode were included after parasitological cure. Monthly infusions of 4mg/kg pentamidine-isethionate diluted in normal-saline were started for 12months. All received antiretroviral therapy (ART). Time-to-relapse or death was the primary end point.

Results

Seventy-four patients were included. The probability of relapse-free survival at 6months and at 12 months was 79% and 71% respectively. Renal failure, a possible drug-related serious adverse event, occurred in two patients with severe pneumonia. Forty-one patients completed the regimen taking at least 11 of the 12 doses. Main reasons to discontinue were: 15 relapsed, five died and seven became lost to follow-up. More patients failed among those with a CD4+cell count ≤ 50cells/μl, 5/7 (71.4%) than those with counts above 200 cells/μl, 2/12 (16.7%), (p = 0.005).

Conclusion

Pentamidine secondary prophylaxis led to a 29% failure rate within one year, much lower than reported in historical controls (50%-100%). Patients with low CD4+cell counts are at increased risk of relapse despite effective initial VL treatment, ART and secondary prophylaxis. VL should be detected and treated early enough in patients with HIV infection before profound immune deficiency installs.     

Two sequence alterations,a 136 bp InDel and an A/C polymorphic site,in the S5 locus are associated with spikelet fertility of indica-japonica hybrid in rice

The rice indica/japonica hybrid shows strong heterosis.However,such inter-subspecific hybrid can't be directly used in rice production due to its low spikelet fertility.The S5 locus was proved to be associated with fertility of indica/japonica hybrid and its S5n allele from wide-compatibility variety (WCV) is capable to overcome fertility barrier.In the present study,we reported the causal sites in the S5 locus responsible for compatibility of indica/japonica hybrid.Fine-mapping of the S5 locus using the 11...     

Quality of maternal and neonatal care in Albania, Turkmenistan and Kazakhstan: a systematic, standard-based, participatory assessment

Background

Progress in maternal and neonatal mortality has been slow in many countries despite increasing access to institutional births, suggesting deficiencies in the quality of care. We carried out a systematic assessment of the quality of maternal and newborn care in three CEE/CIS countries, using an innovative approach to identify priority issues and promote action.

Methods

A standard-based tool, covering over 400 items grouped in 13 main areas ranging from support services to case management, was used to assess a sample of ten maternity hospitals in Albania, Kazakhstan and Turkmenistan. Sources of information were visit to services, medical records, observation of cases, and interviews with staff and mothers. A score (range 0 to 3) was attributed to each item and area of care. The assessment was carried out by a multidisciplinary team of international and national professionals. Local managers and staff provided the necessary information and were involved in discussing the findings and the priority actions.

Results

Quality of care was found to be substandard in all 13 areas. The lowest scores (between one and two) were obtained by: management of normal labour, delivery, obstetric complications and sick babies; infection prevention; use of guidelines and audits; monitoring and follow-up. Neonatal care as a whole scored better than obstetric care. Interviewed mothers identified lack of information, insufficient support during labour and lack of companionship as main issues. Actions to improve quality of care were identified at facility as well as at central level and framed according to main health system functions.

Conclusions

Quality of care is a key issue to improve maternal and neonatal outcomes, particularly in countries such as CEE/CIS where access to institutional births is nearly universal. Approaches that involve health professionals and managers in comprehensive, action-oriented assessments of quality of care are promising and should be further supported.     

核糖开关与基因表达调控

核糖开关(riboswitch)是近几年基因表达调控研究的一个热点.核糖开关位于mRNA的非翻译区(untranslated regions, UTR),能够直接感受胞内外信号并引起自身二级结构的变化,在转录或后转录（翻译和mRNA稳定性）水平实现对下游相关基因的表达调控,该过程不依赖于包括蛋白质在内的其它任何因子的作用. 根据现已发现的核糖开关所能识别的信号因子类型,可以将其分为4类,即小分子代谢物、金属离子、环境因素及空载tRNA敏感的核糖开关;其中,小分子代谢物敏感的核糖开关是发现和研究最多且最深入的一类. 随着研究的深入,将会有更多的核糖开关被发现,这不仅有助于理解生物进化与环境适应性,而且在生物学基础研究,新型药物的开发以及工业生产领域都将发挥重要作用.     

Genetic Engineering of Energy Crops: A Strategy for Biofuel Production in China

Biomass utilization is increasingly considered as a practical way for sustainable energy supply and long-term environment care around the world.In concerns with food security in China,starch or sugar-based bioethanol and edible-oil-derived biodiesel are harshly restricted for large scale production.However,conversion of lignocellulosic residues from food crops is a potential alternative.Because of its recalcitrance,current biomass process is unacceptably expensive,but genetic breeding of energy crops is a p...     

豆蚜在不同品种扁豆上的取食行为

在温室栽培不同品种的扁豆(Dolichos lablab),采用接蚜,光暗对照,隔离饲育,离体饲育,蜡膜人工饲液饲育以及用昆虫取食行为自动测试仪对其取食行为进行测试等方法来鉴定不同扁豆品种对豆蚜(Aphis craccivora Koch)的抗性,确认紫色品种对豆蚜具有拒食作用.分离,提取了扁豆所含的色素成分并对豆蚜进行生物测定,确定扁豆的红色“色素”是抗蚜的物质基础.用进一步提纯的红色“色素”对豆蚜进行取食行为测试,得出拒食强度的初步数据.     

Characterization of T.aestivum-H.californicum chromosome addition lines DA2H and MA5H

In order to transfer useful genes of Hordeum californicum into common wheat(Triticum aestivum L.),the T.aestivum c.v.Chinese Spring(CS)-H.californicum amphiploid was crossed to CS,and its backcrossing and self-fertilized progenies were analyzed by morphological observation,cytological,biochemical and molecular marker techniques.Alien addition lines with two H.californicum chromosomes were identified and their genetic constitution was characterized.STS-PCR analysis using chromosome 2B specific markers indica...