Evaluating time to cancer recurrence as a surrogate marker for survival from an information theory perspective

The last two decades have seen a lot of development in the area of surrogate marker validation. One of these approaches places the evaluation in a meta-analytic framework, leading to definitions in terms of trial- and individual-level association. A drawback of this methodology is that different settings have led to different measures at the individual level. Using information theory, Alonso et al. proposed a unified framework, leading to a new definition of surrogacy, which offers interpretational advantages and is applicable in a wide range of situations. In this work, we illustrate how this information-theoretic approach can be used to evaluate surrogacy when both endpoints are of a time-to-event type. Two meta-analyses, in early and advanced colon cancer, respectively, are then used to evaluate the performance of time to cancer recurrence as a surrogate for overall survival.     

Multicentre trials: a US regulatory perspective

Multicentre trials are very common in the field of drug development. In recent years, multicentre trials have taken on a multinational and multiregional aspect. We provide a conceptual framework for the use of multicentre trials in the context of drug development, from the perspective of drug regulation in the United States. In this paper, we review some regulatory history, milestones and standards as they relate to multicentre trials. Special attention is given to the similarities and differences in the approaches to multicentre trials in the following documents; Guideline for the Format and Content of the Clinical and Statistical Sections of New Drug Applications, International Conference on Harmonization, Draft Guideline on Statistical Principles for clinical trials and the Guidance for Industry Providing Clinical Evidence of Effectiveness for Human Drug and Biologic Products. The paper includes a consideration of some of the issues in the analysis of data from multicentre trials.     

硫酸盐在玻璃澄清中的若干问题探讨

阐述了硫酸盐在高温玻璃熔体中可能发生的化学反应以及硫酸盐发生热分解反应达到平衡时的平衡常数热力学表达式,讨论了硫酸盐在玻璃熔体中作为澄清剂的澄清机理,介绍了硫在玻璃基体中可能存在的价态以及影响硫在玻璃体中的含量的因素。     

Use of some plant wastes as fillers for polypropylene

Palm kernel shell and the palm fruit pulp fiber were used as additives for polypropylene. The mechanical properties of the polymer, namely, tensile strength, impact strength, surface hardness, and flexural modulus were remarkably enhanced. This was attributed to the fact that these solid wastes functioned as reinforcing fillers through bonding interactions and stress‐sharing mechanisms. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1447–1452, 2003     

Use of some essential oils as natural preservatives for butter

Thyme and cumin essential oils were used in the present study in an attempt to prevent butter deterioration during storage at room temperature. Butter oxidation and lipolysis were followed by measuring the acid, peroxide and TBA values. Lipolytic activity and total microbial and lipolytic bacterial counts were also measured. During butter storage, very little change in the peroxide and TBA values were found while a gradual increase in the acid value was noticed. The addition of cumin and thyme oils at 200 ppm to butter caused very little increase in the acid value. The data for lipolytic bacterial counts were in general agreement with the acid values. Thyme and cumin essential oils showed a greater anti-hydrolytic effect and act as superior preservatives compared to BHT.     

Design and analysis issues in cluster-randomized trials of interventions against infectious diseases

This paper discusses the application of the cluster-randomized trial (CRT) design to evaluate the effectiveness of interventions against infectious diseases. In addition to the usual rationale for this design, there are a number of other advantages that are peculiar to the study of infectious diseases. In particular, CRTs are able to measure the overall effect of an intervention at the population level, capturing both the direct effect of an intervention on an individual's susceptibility to infection, and also the indirect effects due to changes in risks of transmission to other individuals, or to the mass effect or 'herd immunity' resulting from intervening in a large proportion of the population. We briefly review published CRTs of interventions against infectious diseases, most of which have been conducted in the developing countries where such diseases predominate. The focus is on trials in which communities or other large groupings are randomized, and in which impacts on infectious disease incidence or mortality are assessed. We then discuss three issues that are of special relevance to CRTs of infectious diseases. First, issues relating to the definition and size of clusters; secondly, the role of matching or stratification, and the choice of matching factors; and thirdly, the definition of direct and indirect effects of intervention, and methods of assessing these components in a CRT. We conclude by outlining some areas for future research.     

Some statistical issues in the design of HIV-1 vaccine and treatment trials

This article summarizes material on statistical issues in the design of HIV-1 preventive vaccine trials and antiretroviral HIV-1 treatment trials that was presented at the first school on Modern Statistical Methods in Medical Research, held at the International Centre for Theoretical Physics in Trieste, in September 1999. Design issues for the two trial types are discussed separately and are compared, which highlights the relative complexity of vaccine trials. Vaccine trial designs for assessing various vaccine effects are considered, including classical double-blind individual-randomized designs for evaluating biological vaccine effects on susceptibility to infection, and augmented partners, cluster-randomized, and infant designs for evaluating biological vaccine effects on infectiousness as well as on susceptibility. Within these designs, covered topics include surrogate endpoints for measuring vaccine effects on secondary transmission and on HIV-1 disease progression, and exploratory and confirmatory methods for assessing host immune and viral genotypic or phenotypic correlates of vaccine protection against infection or disease. For antiretroviral trials, covered topics include endpoint selection and structured designs such as fractional factorial and Latin square designs for rapidly screening combination drug regimens and for identifying patterns of HIV-1 genomic evolution that predict loss of drug efficacy.     

Allanblackia Oil: Phytochemistry and Use as a Functional Food

The consumption and commercial exploitation of Allanblackia (Clusiaceae) seed oils is of current interest. The favorable physicochemical characteristics of Allanblackia oil (solid at room temperature; high stearic acid content) lend food products that contain it (i.e., vegetable-based dairy products, ice cream, spreads) health advantages over others that contain higher levels of lauric, myristic, and/or palmitic acids, which can increase blood cholesterol levels. Such considerations are important for individuals prone to cardiovascular disease or with hypercholesterolemia. Domestication projects of several Allanblackia species in tropical Africa are underway, but wildcrafting of fruits to meet the seed demand still occurs. Proper species authentication is important, since only authenticated oil can be deemed safe for human consumption. The chemical constituency of Allanblackia seed oils, and potential roles of these phytochemicals in preventive strategies (e.g., as part of a healthy diet) and as pharmacological agents used to treat chronic disease were examined in this review. The primary and secondary metabolite constituency of the seed oils of nearly all Allanblackia species is still poorly known. The presence, identity, and quantity of potentially bioactive secondary metabolites in the seed oils, and pharmacological testing of isolated compounds were identified as important directions for future research.     

硝酸磷肥酸解工序的操作和问题探讨

介绍硝酸磷肥装置酸解工序流程,工艺控制指标,影响P2O5分解率的因素,生产中存在的问题及解决方法。     

Study of the acid character of some palladium-modified pillared clay catalysts: Use of isopropanol decomposition as test reaction

Preparation, textural and structural characterizations as well as acid properties of some aluminium, zirconium pillared montmorillonite (from Algerian bentonite) and including alumina or zirconium pillared montmorillonite supported palladium are reported. Heat resistant basal spacings of 1.7 nm, surface areas in the range of 250–300 m²/g and micropore volumes of about 0.1 cm³/g were obtained. The acid activation of montmorillonite prior pillaring conduces to a resulting material with significantly higher pore volume and acidity. The improvement in acidity is mainly of the Brønsted acid type. The modification of zirconium-pillared montmorillonite with sulfate ions affects the structural properties of the pillared sample but gives a material with strong acid properties and both Lewis and Brønsted acid types are enhanced. It is reported also that textural and structural properties are not affected by the impregnation of a metallic function (1 wt.% Pd loading) but the acid properties changed. The pillared montmorillonite supported palladium has more Brønsted acidity than does the pillared montmorillonite. Decomposition of isopropanol was studied on these systems at low reaction temperature.     

904L钢在湿法磷酸装置中的应用及应注意的问题

1 904L钢在湿法磷酸装置中的腐蚀形式904L钢是一种高镍、高铬、超低碳奥氏体不锈钢[1],因其优良的耐腐蚀性能、良好的加工性能、较高的强度而被优先用作磷酸装置萃取槽、熟化槽的预埋件、搅拌桨、料浆管道等。从长期生产实践看,904L钢在磷酸装置中的腐蚀形式主要表现为:1)磨蚀。如904L钢用于萃取槽、熟化槽的搅拌桨时,由于介质中含固量高达25%[2],搅拌桨转速一般75 r/m in,长期转动桨叶会出现沟槽状磨蚀。磨蚀部分多从桨叶线速度最大处逐渐向根部延伸。2)全面腐蚀。虽然904L钢在硫、磷混酸中具有优良的耐腐蚀性能,但全面腐蚀依然存在,反应…     

Green Chemistry in Protected Horticulture: The Use of Peroxyacetic Acid as a Sustainable Strategy

Global reduction of chemical deposition into the environment is necessary. In protected horticulture, different strategies with biodegradable products are used to control pathogens. This review presents the available tools, especially for the management of protected horticultural species, including vegetables and ornamental plants. An analysis of the potential for degradable products that control pathogens and also encourage other productive factors, such as oxygen in the root system, is presented. Biosecurity in fertigation management of protected horticulture is conducted by using peroxyacetic acid mixtures that serve three basic principles: first, the manufacture of these products does not involve polluting processes; second, they have the same function as other chemicals, and third, after use and management there is no toxic residue left in the environment. The sustainability of protected horticulture depends on the development and introduction of technologies for implementation in the field.     

Use of earthworms as a protein supplement in diets for rabbits

The purpose of the present study was to evaluate the nutritive value of earthworms as protein feed in rabbit rations. Earthworm meal was obtained from Eisenia foetida and Lumbricus rubellus. Its proximate chemical composition, amino acid composition and protein digestibility in vitro were determined. In addition, growing rabbits were fed a diet containing 30% of the total protein as earthworm meal, diet which was compared with a control diet containing soybean meal as protein feed. Both diets were isocaloric and isonitrogenous. Feed intake, weight gain, feed conversion and apparent digestibility were measured. Results showed high protein (50.86%) and fat (10.16%) contents, and low fiber percentage (2.67%). Amino acids content including the essential, and in vitro protein digestibility percentage were similar to fish and meat meals and higher than soybean meal. There were no differences in feed intake, weight gain and feed conversion. Apparent digestibility was 5.09% higher (P less than 0.05) with the diet containing earthworm meal than with the control diet. It was concluded that it is possible to substitute 30% of the protein in the diet of growing rabbits, with earthworm meal, without any adverse physiological effects. Similar results to those achieved when conventional protein supplements are used for rabbit rations, were obtained.     

Use of epoxidized natural rubber as a toughening agent in plastics

At present, the rubber toughening of plastics has become an attractive field of study in polymer science and technology because brittleness is known to be a drawback in many engineering plastics; it can cause premature failure during application. Among existing rubber materials, epoxidized natural rubber (ENR) has been widely used as an impact modifier or toughening agent in a large number of engineering plastics; in particular, it enhances the impact strength, which deteriorates with the incorporation of other additives, such as fillers and flame retardants. ENR is a modification product from natural rubber produced via an epoxidation reaction. ENR also has good chemical resistance. In this review, we aim to provide a concise current status in the field of ENR toughening agents for plastics with a brief discussion of their associated problems and potential applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42270.     

Use of Oxide Ceramic as a Functional Protective Barrier

Features of the process of formation of ceramic coatings using the method of anode microscopic-arc oxidation (AMAO) are discussed and results of a study of the effect due to electrolyte composition and AMAO electrophysical parameters on the growth kinetics and structure of ceramic layers are given.