Crystal structure of the S187F variant of human liver alanine: Aminotransferase associated with primary hyperoxaluria type I and its functional implications

The substitution of Ser187, a residue located far from the active site of human liver peroxisomal alanine:glyoxylate aminotransferase (AGT), by Phe gives rise to a variant associated with primary hyperoxaluria type I. Unexpectedly, previous studies revealed that the recombinant form of S187F exhibits a remarkable loss of catalytic activity, an increased pyridoxal 5′‐phosphate (PLP) binding affinity and a different coenzyme binding mode compared with normal AGT. To shed light on the structural elements responsible for these defects, we solved the crystal structure of the variant to a resolution of 2.9 Å. Although the overall conformation of the variant is similar to that of normal AGT, we noticed: (i) a displacement of the PLP‐binding Lys209 and Val185, located on the re and si side of PLP, respectively, and (ii) slight conformational changes of other active site residues, in particular Trp108, the base stacking residue with the pyridine cofactor moiety. This active site perturbation results in a mispositioning of the AGT‐pyridoxamine 5′‐phosphate (PMP) complex and of the external aldimine, as predicted by molecular modeling studies. Taken together, both predicted and observed movements caused by the S187F mutation are consistent with the following functional properties of the variant: (i) a 300‐ to 500‐fold decrease in both the rate constant of L‐alanine half‐transamination and the k_cat of the overall transamination, (ii) a different PMP binding mode and affinity, and (iii) a different microenvironment of the external aldimine. Proposals for the treatment of patients bearing S187F mutation are discussed on the basis of these results. Proteins 2013; 81:1457–1465. © 2013 Wiley Periodicals, Inc.     

Palaeoenvironmental significance of the green alga Botryococcus in the lacustrine rotliegend (upper carboniferous ‐ lower permian)

The green alga Botryococcus is an important component of the phytoplankton in lake sediments from the Rotliegend of Central Europe. The first microscopic fossils from the Saar‐Nahe Basin that can be assigned to this genus are described and illustrated here. Their distribution at various stratigraphic levels shows that the primary production of the lakes was at least partially controlled by these green algae. The frequency of fossils in the sediments is correlated with grain size, which varied with the depositional environment. Their abundance is greater in sediments deposited in shallow water, especially in small lakes and in the littoral environments of larger lakes. Sediments of deep‐water lake bottoms contain only minor amounts of algal remains. The abundance of kerogen originating from phytoplankton and occurrences of Botryococcus fossils are correlated in these lake deposits.     

Short-term succession of marine microbial fouling communities and the identification of primary and secondary colonizers

Microbial succession during the initial stages of marine biofouling has been rarely studied, especially in the Arabian Gulf. This study was undertaken to follow temporal shifts in biofouling communities in order to identify primary and secondary colonizers. Quantitative analysis revealed a significant increase in total biomass, coverage of macrofoulers, chlorophyll a concentrations, and bacterial counts with time. The relative abundance of the adnate diatoms increased with time, whereas it decreased in the case of the plocon diatoms. Non-metric multidimensional scaling (NMDS) ordination based on MiSeq data placed the bacterial communities in three distinct clusters, depending on the time of sampling. While the relative abundance of Alphaproteobacteria and Flavobacteriia decreased with time, suggesting their role as primary colonizers, the relative abundance of Actinobacteria and Planctomycetia increased with time, suggesting their role as secondary colonizers. Biofouling is a dynamic process that involves temporal quantitative and qualitative shifts in the micro- and macrofouling communities.     

The Challenge of Antibiotic-Resistant Staphylococcus: Lessons from Hospital Nurseries in the mid-20th Century

In the late 1940s, epidemics of antibiotic-resistant strains of Staphylococcus aureus began to plague postpartum nurseries in hospitals across the United States. Exacerbated by overcrowding and nursing shortages, resistant S. aureus outbreaks posed a novel challenge to physicians and nurses heavily reliant on antibiotics as both prophylaxis and treatment. This paper explores the investigation of the reservoir, mode of transmission, and virulence of S. aureus during major hospital outbreaks and the subsequent implementation of novel infection control measures from the late 1940s through the early 1960s. The exploration of these measures reveals a shift in infection control policy as hospitals, faced with the failure of antibiotics to slow S. aureus outbreaks, implemented laboratory culture routines, modified nursery structure and layout, and altered nursing staff procedures to counter various forms of S. aureus transmission. Showcasing the need for widespread epidemiologic surveillance, ultimately manifesting itself in specialized “hospital epidemiology” training promoted in the 1970s, the challenges faced by hospital nurses in the 1950s prove highly relevant to the continued struggle with methicillin-resistant Staphylococcus aureus (MRSA) and other resistant nosocomial infections.     

N- versus O-alkylation: Utilizing NMR methods to establish reliable primary structure determinations for drug discovery

A classic synthetic issue that remains unresolved is the reaction that involves the control of N- versus O-alkylation of ambident anions. This common chemical transformation is important for medicinal chemists, who require predictable and reliable protocols for the rapid synthesis of inhibitors. The uncertainty of whether the product(s) are N- and/or O-alkylated is common and can be costly if undetermined. Herein, we report an NMR-based strategy that focuses on distinguishing inhibitors and intermediates that are N- or O-alkylated. The NMR strategy involves three independent and complementary methods. However, any combination of two of the methods can be reliable if the third were compromised due to resonance overlap or other issues. The timely nature of these methods (HSQC/HMQC, HMBC. ROESY, and ¹³C shift predictions) allows for contemporaneous determination of regioselective alkylation as needed during the optimization of synthetic routes.     

Synthesis and biological evaluation of novel alkyl amide functionalized trifluoromethyl substituted pyrazolo[3,4-b]pyridine derivatives as potential anticancer agents

A series of novel alkyl amide functionalized trifluoromethyl substituted pyrazolo[3,4-b]pyridine derivatives 5, 6 and 7 were prepared starting from 6-phenyl-4-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-3-amine 3 via selective N-alkylation, followed by reaction with different primary aliphatic amines, cyclic secondary amines or l-amino acids under different set of conditions. All the synthesized compounds 5, 6 and 7 were screened for anticancer activity against four cancer cell lines such as A549—Lung cancer (CCL-185), MCF7—Breast cancer (HTB-22), DU145—Prostate cancer (HTB-81) and HeLa—Cervical cancer (CCL-2). The compounds 5i and 6e are found to have promising bioactivity at micro molar concentration.     

上海市医院预约诊疗服务实施效果分析

?????? 目的 对上海市医院预约诊疗服务的实施效果进行分析,为今后预约诊疗服务工作的推进提供参考依据。方法 通过现场问卷、专家小组访谈、数据采集等方式,了解预约诊疗服务实施效果。结果 预约诊疗服务的信息系统、服务系统、管理系统和评价系统逐渐完善,并在预约诊疗服务的实施过程中发挥出巨大作用。结论 预约就医模式已经逐步被患者所接受,其能有效减少患者就医中的无效等候时间,缓解目前存在“看病难”、医疗资源分配不合理等问题,但无法从根本上解决医疗资源稀缺、供求关系不均等的问题。     

县级公立医院人才队伍建设存在的问题及路径探讨

新医改背景下,如何引进优秀医学毕业生到县级医院工作,加强对县级医院人才队伍的培养,改革其人事制度,是县级医院亟需解决的问题。县级医院应牢牢抓住新医改中加强基层医疗服务体系建设的机遇,制定科学的人才引进、培养规划,改革人事分配制度,营造尊重知识、尊重人才的良好氛围,走可持续发展之路。     

我国公立医院财政补偿机制与方法研究

财政补偿机制改革关系到公立医院改革目标的实现。在深入理解医院公益性内涵的基础上,针对财政补偿对医院公益性的影响,结合当前补偿思路存在的问题,以解决“看病难、看病贵”问题为目标,提出了基于时序比较的财政补偿机制,给出了相应的财政补偿方法。     

论医院绩效管理的人性化管理及其柔性化操作

医院绩效管理中存在倾向于刚性管理并热衷于惩罚方式的现象,其结果是无意中起了引导员工为逃避惩罚而隐瞒相关信息的作用,从而使医院员工不能共同分享与讨论各种经验教训,不利于医院进行持续质量改进。而有效预防与解决这一问题的主要策略是在绩效管理中进行人性化管理,并以柔性化操作处理那些不易进行刚性考核或易在刚性考核中产生消极后果的问题。