Comparison of ITS RFLP patterns of Gracilaria (Rhodophyceae, Gracilariales) populations from Chile and New Zealand and an examination of interfertility of Chilean morphotypes

Restriction fragment length polymorphism (RFLP) patterns of the internal transcribed spacer (ITS) of the nuclear ribosomal cistron and crossability trials were used to characterize four morphotypes of Gracilaria from Lenga, Isla Santa María and Maullín, Chile, and two morphotypes from sites in New Zealand. PCR products from all Chilean morphotypes resulted in a major single band of ca. 1198 bp. ITS-RFLP profiles generated with the restriction enzymes Cla I, Hae III, Pst I, Hha I, Rsa I and Taq I, were identical in all cases. All crosses within, as well as between, morphotypes resulted in cystocarp differentiation, with the production of viable carpospores. Based upon these data, it is concluded that the four morphotypes from Chile correspond to a single species, G. chilensis, and that the ITS-RFLP pattern is a useful marker to predict genetic relatedness at the specific level in Gracilaria. A comparison of the ITS-RFLP patterns of the Chilean morphotypes with the patterns of two samples of G. chilensis from New Zealand revealed that the sample from Scorching Bay, Wellington, fits the Chilean ITS-RFLP patterns. The population from Blockhouse Bay, Auckland, appears to correspond to another species. This revised version was published online in July 2006 with corrections to the Cover Date.     

TREATMENT NEEDS IN HIV PREVENTION TRIALS: USING BENEFICENCE TO CLARIFY SPONSOR‐INVESTIGATOR RESPONSIBILITIES

Some participants will get HIV‐infected in HIV prevention trials, despite risk reduction measures. The subsequent treatment responsibilities of sponsor‐investigators have been widely debated, especially where access to antiretroviral therapy (ART) is not available. In this paper, we explore two accounts of beneficence to establish whether they can shed light on sponsor‐investigator responsibilities. We find the notion of general beneficence helpful insofar as it clarifies that some beneficent actions will be obligatory where they can be dispensed without scuppering the trial. We find the notion of specific beneficence helpful insofar as it directs investigators to attend to the needs of trial participants; however the range of interventions that could be provided remains unhelpfully broad. We then examine accounts of the investigator‐participant relationship to narrow the range of interventions that investigators should provide, concluding that health‐care, and HIV infection, are appropriate foci. We conclude that when investigators are able to meet the ART needs of their participants (e.g. referral, assisted referral or direct provision) without sacrificing trial quality, they must do so. However, there is little of this explicit direction to be found in the account of specific beneficence itself, but rather it is found in accounts of the relationship that are compatible with beneficence.     

A New Class of Completely Self‐Designing Clinical Trials

A flexible method is proposed for group sequentially performed clinical trials which allows for an adaptive, data‐driven sample size reassessment at each stage. By also adaptively assigning different weights to the several stages the total number of study parts can be steered to an intended early or late end of the trial in dependence on all information available prior to a stage. Although at each stage the null hypothesis is tested on rejection, the full level‐α‐test is preserved at the end of the study. The proposed method is not restricted to normally distributed responses. The discussed adaptive designing is a useful tool provided that a priori information about parameters involved in the trial are not available or subject to uncertainty. The presented learning algorithm enables the complete self‐designing of a study.     

Estimating risk difference in multicenter studies under baseline-risk heterogeneity

In this paper, we consider the case of efficient estimation of the risk difference in a multicenter study allowing for baseline heterogeneity. We consider the optimally weighted estimator for the common risk difference and show that this estimator has considerable bias when the true weights (which are inversely proportional to the variances of the center-specific risk difference estimates) are replaced by their sample estimates. In addition, we propose a new estimator for this situation of the Mantel-Haenszel type that is unbiased and, in addition, has a smaller variance for small sample sizes within the study centers. Simulations illustrate these findings.     

Transnational Medicine in Public Arenas: Aids Treatments in the South

This article looks at the AIDS-related controversy surrounding the experiments on and the availability of medicines in southern countries. It situates these debates in a longer-term history of transnational medicine. It highlights the rise of international therapeutic modernity at the beginning of the 1990s, based on the strict regulation of clinical trials and on the formalization of the international ethical rules governing experiments. This rise helped to change radically the reception of experiments conducted in southern countries around AIDS. With regard to this new ethics applied to clinical trials in southern countries, this article goes on to demonstrate the confrontation at the end of the 1990s between two different approaches to the universalization of healthcare. Finally, it shows how new laws on international trade have reinitiated this confrontation. Through this story, the article suggests in what sense the study of the political transformations of transnational medicine could offer a new field of investigation for the social sciences.     

A Comment on La Vaque and Rossiter

The paper by La Vaque and Rossiter recommends that placebo-controlled trials only be conducted when best proven treatments are not available. In this comment, I review evidence suggesting that identifying best proven treatments is a complex task involving many variables and that making such a decision entails many real-world difficulties.     

Enhanced fructose levels in field grown potato tubers expressing a thermostable glucose isomerase

A thermostable glucose isomerase was expressed in Solanum tuberosum Desirée using the tuber-specific granular-bound starch synthase promoter. The fructose content was substantially increased in microtubers, greenhouse grown tubers as well as tubers produced in field trials as compared with the controls. Furthermore, the tuber yield of field grown potatoes was enhanced by 30% in the transgenic lines (from 1.04 kg/plant in the wild type to 1.36 kg/plant in the transgenic lines).     

新型双特异性单链抗体BiTEs及其在肿瘤治疗中的应用前景

BiTEs(bispecificTcellengagers)是一种以T细胞作为效应细胞的双特异性单链抗体 ,它具有两个抗原结合臂 ,可以同时和T细胞及靶细胞结合 ,并激活细胞毒性T细胞杀伤病变细胞。和其它双特异性抗体相比 ,BiTEs的分子柔韧性更好 ,能更好地促进CD3复合体和肿瘤靶标的连接 ,并且它不受T细胞受体和靶细胞上MHCⅠ类分子的约束 ,不需要共刺激分子的参与 ,是一种极具应用潜力的抗体形式。就BiTEs的结构、作用机理及其在肿瘤临床上的应用前景几个方面做一综述。     

Menadione sodium bisulphite: A promising plant growth regulator

Menadione sodium bisulphite (MSB) increased the growth of tomato plants and alfalfa callus and stimulated rooting of mungbean cuttings. Investigations into its effect on auxin metabolism resulted in decreased activities of the enzymes involved in IAA oxidation in tomato plants. The levels of IAA were increased by about 3 to 4 fold following application of MSB to tomato, cucumber, corn and capsicum plants.NCL Communication No. 3358.