Characterization of a thymidylate synthase (TS)-inducible cell line: a model system for studying sensitivity to TS- and non-TS-targeted chemotherapies.

Thymidylate synthase (TS) is responsible for the de novo synthesis of thymidylate, which is required for DNA synthesis and repair and which is an important target for fluoropyrimidines such as 5-fluorouracil (5-FU), and antifolates such as Tomudex (TDX), ZD9331, and multitargeted antifolate (MTA). To study the importance of TS expression in determining resistance to these agents, we have developed an MDA435 breast cancer-derived cell line with tetracycline-regulated expression of TS termed MTS-5. We have demonstrated that inducible expression of TS increased the IC(50) dose of the TS-targeted therapeutic agents 5-FU, TDX, and ZD9331 by 2-, 9- and 24-fold respectively. An IC(50) dose for MTA was unobtainable when TS was overexpressed in these cells, which indicated that MTA toxicity is highly sensitive to increased TS expression levels. The growth inhibitory effects of the chemotherapeutic agents CPT-11, cisplatin, oxaliplatin, and Taxol were unaffected by TS up-regulation. Cell cycle analyses revealed that IC(50) doses of 5-FU, TDX and MTA caused an S-phase arrest in cells that did not overexpress TS, and this arrest was overcome when TS was up-regulated. Furthermore, the S-phase arrest was accompanied by 2- to 4-fold increased expression of the cell cycle regulatory genes cyclin E, cyclin A, and cyclin dependent kinase 2 (cdk2). These results indicate that acute increases in TS expression levels play a key role in determining cellular sensitivity to TS-directed chemotherapeutic drugs by modulating the degree of S-phase arrest caused by these agents. Moreover, CPT-11, cisplatin, oxaliplatin, and Taxol remain highly cytotoxic in cells that overexpress TS.

Patients' experiences and views of clinical trials.

UNLABELLED: This article explores whether the experience of participating in a clinical trial was similar to what patient volunteers had expected, prior to agreeing to take part. It also considers patients' views on four aspects of participation that may help to determine whether the decision to become a research subject was truly an autonomous one, namely: whether patients feel that (i) doctors 'know best' when it comes to taking part in a trial; (ii) refusing to take part would upset the doctor; (iii) there is little risk associated with participation, and (iv) people have a moral duty to be involved in such trials. FINDINGS: More than a third of patients had no particular expectations of what trial participation would be like. Over half did not believe that doctors knew best about whether or not they should participate, and the vast majority rejected the proposition that a refusal to participate would have upset the doctor. Half of the patients believed that there was little risk in testing new drugs, and most felt that people do not have a moral duty to become research subjects.

Information giving in clinical trials: the views of medical researchers.

It is both an ethical and legal requirement that patients who participate in clinical trials must generally give their consent. As part of this process, patients must be provided with adequate information to enable them to decide whether or not to take part. In the UK, the pharmaceutical companies that sponsor such research, as well as Local Research Ethics Committees, specify in detail the information that must be given to trial participants. The researchers who conduct clinical trials inevitably form views on the amount of information they are required to provide, and about patients' comprehension of that information. The literature in this area suggests that some medical researchers may be unhappy with the amount of information that they must give patient participants. There have been, however, few systematic attempts to determine their views. This paper reports a study that explored researchers' views as to (i) the amount of information provided to trial participants, and (ii) participants' understanding of that information. Researchers generally felt that they were required to give trial participants an appropriate amount of information, and that most patients had at least a reasonable understanding of key aspects of the clinical trials' process. However, there were differing views as to the level of information that they felt patients themselves wanted. The researchers did not generally feel that the patients' inability to comprehend information rendered the process of obtaining 'informed consent' a waste of time. However, some did believe that they were required to burden patients with excessive information.

Causing death or allowing to die? Developments in the law.

Several cases which have been considered by the courts in recent years have highlighted the legal dilemmas facing doctors whose decisions result in the ending of a patient's life. This paper considers the case of Dr Cox, who was convicted of attempting to murder one of his patients, and explores the roles of motive, diminished responsibility and consent in cases of "mercy killing". The Cox decision is compared to that of Tony Bland and Janet Johnstone, in which the patients were in a persistent vegetative state. In all three cases, the doctors believed that their patients' quality of life was so poor that their continued existence was of no benefit to them, and decided that their lives should not be unduly prolonged, yet the doctor who was prosecuted was the one whose dying patient had requested that her death be hastened. The paper examines the law's seemingly contradictory approaches to such cases.

Patients' perceptions of information provided in clinical trials.

BACKGROUND: According to the Declaration of Helsinki, patients who take part in a clinical trial must be adequately informed about the trial's aims, methods, expected benefits, and potential risks. The declaration does not, however, elaborate on what "adequately informed" might amount to, in practice. Medical researchers and Local Research Ethics Committees attempt to ensure that the information which potential participants are given is pitched at an appropriate level, but few studies have considered whether the patients who take part in such trials feel they have been given adequate information, or whether they feel able to understand that information. OBJECTIVES: To explore trial participants' views (i) on the amount of information provided, and (ii) of their own understanding of that information. DESIGN: Structured interviews of patients participating in clinical trials for the treatment of chronic medical condition. FINDINGS: Patients generally felt they were given an appropriate amount of information, and that they were able to understand all or most of it. They felt they were given adequate time to ask questions before agreeing to take part. In comparison with treatment given out with the research setting, patients generally felt they received more information when participating in a clinical trial. CONCLUSIONS: Researchers sometimes complain that patients are given too much information during clinical trials, and have limited understanding of that information. The present study shows that this perception is not necessarily shared by patients. More research is needed in this area, particularly to gauge whether patient understanding is indeed accurate.

Preparation and handling of methacholine chloride testing solutions. Effect of the hygroscopic properties of methacholine.

Persons with hyperreactive airways differ quantitatively from normal persons in their response to bronchial provocation testing with methacholine chloride (Mch). Methacholine chloride has strong hygroscopic properties that necessitate careful dessication, preparation, and handling if accurate results are to be achieved. The rate of hydration of Mch was determined by exposing the drug to various levels of relative humidity. The rate of water uptake was directly related to the availability of water in the atmosphere. At 49% relative humidity, a 0.125%/min gain in weight was noted, which increased to 0.489%/min at 80% relative humidity. Adequate dessication time and technique were determined by noting the time required to return the drug from a hydrated to a dry state. With proper technique, dessication was virtually complete by 4 to 6 h, and 20 to 24 h assured a return to the dry state. From these data, guidelines for preparation and handling of Mch test solutions can be formulated.