阿维链霉菌发酵培养基的优化

通过优化发酵过程中培养基的组成使得阿维链霉菌的发酵单位及有效组分Bla含量提高。采用单因子试验法及均匀设计试验法分析各种营养成分及其配比对阿维链霉菌Co39-15发酵单位和有效组分Bla含量的影响。获得最佳的种子培养基和发酵培养基配方,发酵单位及有效组分Bla含量比原来的发酵水平分别提高了20%～30%、8%～10%。利用单因子试验法及均匀设计试验法对抗生素的发酵培养基进行优化,是一种快速、效果显著的方法。     

Living krill, zooplankton and experimental investigations: a discourse on the role of krill and their experimental study in marine ecology

Krill occupy critical positions in a many marine ecosystems and have been the subject of a number of concerted studies yet there are large areas of their biology that still remain a mystery. Most species of krill are open ocean animals, which makes direct observation and sampling difficult. Krill also exhibit a number of physiological and behavioural attributes which frustrate attempts to understand their life history. Krill are conceptually difficult to come to terms with; they are obviously different from larger marine organisms such as squid, fish, whales and fish yet they are also quite distinct from those animals classed as zooplankton such as copepods. Despite these differences they have most often been grouped with zooplankton and have been studied using techniques developed for animals which are orders of magnitude smaller than they. This mismatch has affected our view of their interactions with the physical world and also affects their perceived trophic interactions. Their size and mobility also interferes with our ability to sample them effectively and thus to develop our appreciation of their true role in the marine ecosystem. Understanding how intermediate-sized animals, such as krill, function in aquatic ecosystem is critical to better management of the marine environment.     

The west's Dismissal of the Khabarovsk trial as ‘Communist Propaganda’: Ideology,evidence and international bioethics

In late 1949 the former Soviet Union conducted an open trial of eight Japanese physicians and researchers and four other military servicemen in Khabarovsk, a city in eastern Siberia. Despite its strong ideological tone and many obvious shortcomings such as the lack of international participation, the trial established beyond a reasonable doubt that the Japanese army had prepared and deployed bacteriological weapons and that Japanese researchers had conducted cruel experiments on living human beings. However, the trial, together with the evidence presented to the court and its major findings--which have proved remarkably accurate--was dismissed as communist propaganda and totally ignored in the West until the 1980s. This paper reviews the 1949 Khabarovsk trial, examines the West's dismissal of the proceedings as mere propaganda and draws some moral lessons for bioethics today. As an important historical case, set in the unique socio-political context of the Cold War, the West's dismissal of the trial powerfully illustrates some perennial ethical issues such as the ambivalence of evidence and power of ideology in making (or failing to make) cross-national and cross-cultural factual and moral judgments.     

Cell Cycle Synchronization of the Murine EO771 Cell Line Using Double Thymidine Block Treatment

This study shows that double thymidine block treatment efficiently arrests the EO771 cells in the S-phase without altering cell growth or survival. A long-term analysis of cell behavior, using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) staining, show synchronization to be stable and consistent over time. The EO771 cell line is a medullary breast-adenocarcinoma cell line isolated from a spontaneous murine mammary tumor, and can be used to generate murine tumor implantation models. Different biological (serum or amino acid deprivation), physical (elutriation, mitotic shake-off), or chemical (colchicine, nocodazole, thymidine) treatments are widely used for cell synchronization. Of the different methods tested, the double thymidine block is the most efficient for synchronization of murine EO771 cells if a large quantity of highly synchronized cells is recommended to study functional and biochemical events occurring in specific points of cell cycle progression.     

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli such as endotoxins, bacteria, umbilical cord occlusions, hypoxia and various pharmacological treatments. The life-saving clinical practices of glucocorticoid treatment in fetuses at risk of premature birth and the therapeutic hypothermia have been developed in this model. This is due to the unique amenability of the non-anesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, substance injection, recording of bioelectrical activity, application of electric stimulation and in vivo organ imaging. Here we describe the surgical instrumentation procedure required to achieve a stable chronically instrumented non-anesthetized fetal sheep model including characterization of the post-operative recovery from blood gas, metabolic and inflammation standpoints.     

A matching procedure for sequential experiments that iteratively learns which covariates improve power

We propose a dynamic allocation procedure that increases power and efficiency when measuring an average treatment effect in sequential randomized trials exploiting some subjects' previous assessed responses. Subjects arrive sequentially and are either randomized or paired to a previously randomized subject and administered the alternate treatment. The pairing is made via a dynamic matching criterion that iteratively learns which specific covariates are important to the response. We develop estimators for the average treatment effect as well as an exact test. We illustrate our method's increase in efficiency and power over other allocation procedures in both simulated scenarios and a clinical trial dataset. An R package “SeqExpMatch ” for use by practitioners is available on CRAN .     

Circumcising human subjects: An evaluation of experimental foreskin amputation using the Declaration of Helsinki

This paper explores ethical considerations for active studies of circumcision, i.e., the amputation of the foreskin, in the form of a case study of three major trials performed in African countries in the early 2000s. The paper outlines the function of the foreskin and method and history of its amputation as well as its current use in attempting to combat the global AIDS crisis. These trials are then interrogated in accordance with the Declaration of Helsinki. In particular, the irreversible nature of amputation is given great consideration. The case studies are found to have serious failures in terms of the modern iteration of the Declaration of Helsinki. This paper calls for extreme scrutiny in accordance with international norms relating to the ethical treatment of human subjects in a research context of studies of circumcision if and when they are proposed again.     

Nonhuman Animals,Public Health,and Ethics: A First Step,But…

In December 2015, the Johns Hopkins Bloomberg School of Public Health held the first-ever summit on the intersection between nonhuman animal ethics and human health. The conference covered a variety of issues where animal health intersects with human health, including the wildlife trade, animal agriculture, and animal experimentation. This article provides a brief overview and critique of the summit.