Spontaneous Reversal of P‐Glycoprotein Expression in Multidrug Resistant Cell Lines*

Abstract: Increased expression of P‐glycoprotein encoded by the mdr‐1 gene is a well‐characterised mechanism for resistance to cancer chemotherapeutic drugs in cell lines. However, the P‐glycoprotein expression after removal of the selection pressure has not fully been elucidated. The stability of P‐glycoprotein expression in the presence (+) and absence (?) of vincristine (30 or 150 nM) was studied in multidrug resistant K562 cell lines (VCR30+, VCR150+, VCR30? and VCR150?) for 11 months. The P‐glycoprotein protein and mdr‐1 mRNA levels were determined at regular intervals using flow cytometry and real‐time PCR, respectively. Chemosensitivity to a panel of antineoplastic drugs was measured using an MTT assay. The presence of vincristine (VCR30+ and VCR150+) resulted in high and stable levels of P‐glycoprotein and mdr‐1 mRNA during the whole period compared to wild type. As for the VCR30? and VCR150? subcultures, the expressions of P‐glycoprotein and mdr‐1 mRNA were stable for five months, and then the levels decreased rapidly. Concomitantly, the sensitivity to drugs known as P‐glycoprotein substrates was restored. In conclusion, resistant cells growing in the presence of the inducing drug have a stable P‐glycoprotein expression and resistance level, but removing the inducing drug may result in a sudden and rapid lowering of P‐glycoprotein and mdr‐1 mRNA levels as long as five months after drug withdrawal.     

Pharmacodynamic differences between species exemplified by the novel anticancer agent CHS 828

When a candidate drug enters clinical trials, decisions regarding dosing are mainly based on animal data. Occasionally, toxicity problems are faced in the clinic because of unexpected species differences in pharmacokinetics or pharmacodynamics between humans and preclinical species. Fludarabine and topotecan are examples of such drugs. In the first clinical trials of the new agent CHS 828, the maximum tolerated dose was reached earlier than expected from animal data. This paper discusses the issue of species differences in the development of anticancer drugs, and preclinical models for detection and quantification of such differences. Pharmacokinetic and hematological toxicity data of CHS 828 from studies in rats and humans are presented. In vitro sensitivity to CHS 828 and some established cytotoxic agents was measured in lymphocytes from humans and rats and in a panel of human and rodent cell‐lines. 10–100 times higher CHS 828 exposure was tolerated by rats than by patients. In both in vitro cell systems, CHS 828 showed higher potency in human cells compared to rodent cells. A species difference was evident also for fludarabine, but not for doxorubicin and cisplatin. CHS 828 pharmacokinetics were similar across species. In conclusion, the lower tolerance of CHS 828 in humans than in rats could be detected in vitro in cultures of peripheral lymphocytes. Preclinical studies of species differences could help the interpretation of in vivo effect studies as well as the choice of starting dose for clinical trials. We suggest peripheral lymphocytes from different species as a potential model system for such studies. Drug Dev. Res. 61:218–226, 2004. © 2004 Wiley‐Liss, Inc.     

Gemcitabine plus cisplatin for advanced transitional cell carcinoma of the urinary tract: a phase II multicenter trial

PURPOSE: We determined the activity and toxicity of gemcitabine plus cisplatin in patients with inoperable or metastatic transitional cell carcinoma of the urinary tract. MATERIALS AND METHODS: A total of 54 patients with transitional cell carcinoma, measurable disease and Eastern Cooperative Oncology Group performance status 2 or greater were enrolled in this multicenter phase II trial. Previous adjuvant or neoadjuvant therapy for locally advanced disease was acceptable if it had been completed more than 1 year before study entry. Every 4 weeks patients received 1,000 mg./m.2 gemcitabine intravenously on days 1, 8 and 15, and 70 mg./m.2 cisplatin intravenously on day 2. RESULTS: All patients were evaluable for response and toxicity. Notably only 7 of the 54 patients (13%) previously received chemotherapy in an adjuvant or neoadjuvant setting. Overall we observed 26 objective responses (48%), of which 15% were complete. Median time to progression was 23 weeks and median survival was 54 weeks. Treatment was well tolerated. The main toxicities were leukopenia (grade 3 in 28% and grade 4 in 11% of patients), anemia (grade 3 in 34% and grade 4 in 6%) and thrombocytopenia (grade 3 in 14% and grade 4 in 6%). Other relevant side effects were nausea and vomiting in 20% of cases, fever in 24%, alopecia in 22%, renal failure in 7.4% and mucositis in 2%. CONCLUSIONS: Combined cisplatin plus gemcitabine is highly active in advanced transitional cell carcinoma of the urinary tract with manageable toxicity. The response rate, time to treatment failure and overall survival appeared to be comparable to those achieved with combined methotrexate, vinblastine, doxorubicin and cisplatin. Conversely toxicity appeared lower. Evaluation of this regimen in randomized studies with methotrexate, vinblastine, doxorubicin and cisplatin is strongly suggested.     

Uptake and disposition of inhaled methanol vapor in humans.

Methanol is a widely used solvent and a potential fuel for motor vehicles. Human kinetic data of methanol are sparse. As a basis for biological exposure monitoring and risk assessment, we studied the inhalation toxicokinetics of methanol vapor in four female and four male human volunteers during light physical exercise (50 W) in an exposure chamber. The relative uptake of methanol was about 50% (range 47-53%). Methanol in blood increased from a background level of about 20 to 116 and 244 microM after 2 h exposure at 0, 100 ppm (131 mg/m3) and 200 ppm (262 mg/m3), respectively. Saliva showed substantially higher levels than blood immediately after exposure. This difference disappeared in a few minutes; thereafter the concentrations and time courses in blood, urine, and saliva were similar, with half times of 1.4, 1.7, and 1.3 h, respectively. The postexposure decrease of methanol in exhaled air was faster, with a half time of 0.8 h. The methanol concentrations were approximately twice as high in all four types of biological samples at 200 compared to 100 ppm. No increase in urinary formic acid was seen in exposed subjects. Our study indicates non-saturated, dose-proportional kinetics of methanol up to 200 ppm for 2 h. No gender differences were detected. Similar, parallel patterns were seen with regard to the methanol time courses in blood, urine, and saliva, whereas the concentration in exhaled air decreased markedly faster. Thus, apart from blood and urine, saliva also seems suitable for biomonitoring of methanol exposure.     

Design and Testing of BACRA,a Web-Based Tool for Middle Managers at Health Care Facilities to Lead the Search for Solutions to Patient Safety Incidents

BackgroundLack of time, lack of familiarity with root cause analysis, or suspicion that the reporting may result in negative consequences hinder involvement in the analysis of safety incidents and the search for preventive actions that can improve patient safety.ObjectiveThe aim was develop a tool that enables hospitals and primary care professionals to immediately analyze the causes of incidents and to propose and implement measures intended to prevent their recurrence.MethodsThe design of the Web-based tool (BACRA) considered research on the barriers for reporting, review of incident analysis tools, and the experience of eight managers from the field of patient safety. BACRA’s design was improved in successive versions (BACRA v1.1 and BACRA v1.2) based on feedback from 86 middle managers. BACRA v1.1 was used by 13 frontline professionals to analyze incidents of safety; 59 professionals used BACRA v1.2 and assessed the respective usefulness and ease of use of both versions.ResultsBACRA contains seven tabs that guide the user through the process of analyzing a safety incident and proposing preventive actions for similar future incidents. BACRA does not identify the person completing each analysis since the password introduced to hide said analysis only is linked to the information concerning the incident and not to any personal data. The tool was used by 72 professionals from hospitals and primary care centers. BACRA v1.2 was assessed more favorably than BACRA v1.1, both in terms of its usefulness (z=2.2, P=.03) and its ease of use (z=3.0, P=.003).ConclusionsBACRA helps to analyze incidents of safety and to propose preventive actions. BACRA guarantees anonymity of the analysis and reduces the reluctance of professionals to carry out this task. BACRA is useful and easy to use.     

Actions of Competence in Occupational Therapy Practice: A phenomenological study of practice in narrative form

This study examined the phenomenon ?what are occupational therapists doing when they feel competent?. Data were provided by eleven occupational therapists who narrated clinical cases in which they had felt themselves to be competent. The empirical phenomenological psychological (EPP) method was used to analyse and interpret the data. The result revealed that on a general level the experience of feeling competent as an occupational therapist derived from achieving results in the rehabilitation project that were satisfying for both participants (the therapist and the client). The strategies for accomplishing this were related to the empathic competence of the therapists. This competence involved interpreting clinical situations as well as understanding the relationship between motive, meaning, decision and time. Further it involved bringing objects, in the form of adaptations, technical aids, structures, simplifications or compensations, into the clinical situation. These abilities together had a great impact on the therapeutic outcome by shaping the clients' lifeworld to make it richer and more active.     

Balancing Within Various Discourses—The Art of Being Old and Living as a Sami Woman

The aim of this part of the Umeå 85+ Study was to explore how indigenous women narrate their lives and their experience of being old as Sami women. Interviews with 9 old Sami women were analyzed using grounded theory. The categories identified were “reindeer as the basis of life,” “longing for significant Sami values,” “feeling valued as a Sami woman,” and “changing for survival;” these evolved into the core category: “balancing within various discourses—the art of being old and living as a Sami woman.” Knowing how to balance provided the ability to make use of available opportunities.