Phase 1 Study to Evaluate the Safety of Reducing the Prophylactic Dose of Dexamethasone around Docetaxel Infusion in Patients with Prostate and Breast Cancer

Background: There is little evidence that supports the registered high dose of dexamethasone used around docetaxel. However, this high dose is associated with considerable side effects. This study evaluates the feasibility of reducing the prophylactic oral dosage of dexamethasone around docetaxel infusion. Patients and methods: Eligible patients had a histologically confirmed diagnosis of prostate or breast cancer and had received at least three cycles of docetaxel as monotherapy or combination therapy. Prophylactic dexamethasone around docetaxel infusion was administered in a de-escalating order per cohort of patients. Primary endpoint was the occurrence of grade III/IV fluid retention and hypersensitivity reactions (HSRs). Results: Of the 46 enrolled patients, 39 were evaluable (prostate cancer (n = 25), breast cancer (n = 14). In patients with prostate cancer, the dosage of dexamethasone was reduced to a single dose of 4 mg; in patients with breast cancer, the dosage was reduced to a 3-day schedule of 4 mg–8 mg–4 mg once daily, after which no further reduction has been tested. None of the 39 patients developed grade III/IV fluid retention or HSR. One patient (2.6%) had a grade 1 HSR, and there were six patients (15.4%) with grade I or II edema. There were no differences in quality of life (QoL) between cohorts. Conclusions: It seems that the prophylactic dose of dexamethasone around docetaxel infusion can be safely reduced with respect to the occurrence of grade III/IV HSRs or the fluid retention syndrome.

Effects of a Self-Monitoring Quality of Life Intervention in Outpatients with Breast Cancer: A Preliminary Report of A Randomized Controlled Trial

OBJECTIVE

This preliminary report used data from a randomized controlled clinical trial to investigate the beneficial effects of a self-monitoring quality of life (SMQOL) intervention on communication, medical care and patient outcomes in Japanese women with breast cancer.

METHODS

This study compared a SMQOL intervention group with a control group that received usual care after 4 months on self-efficacy aspects of patient-physician communication among outpatients with breast cancer in Japan using the Perceived Efficacy in Patient-Physician Interactions (PEPPI) questionnaire. Patients were randomly assigned to the intervention and control groups using permuted-block randomization. The intervention groups were asked to complete a paper-based quality-of-life (QOL) questionnaire in addition to the usual care provided in the control group. Analysis of covariance was used to assess the difference in PEPPI scores between the intervention and control groups. Additionally, subgroup analyses were performed for outpatients with breast cancer accompanied by depression or anxiety.

RESULTS

In total, 232 patients were eligible for this study and randomized. Seven patients did not answer the PEPPI questionnaire at baseline after group allocation, leaving 225 patients for inclusion in the analyses. The modified intention-to-treat ITT analysis showed the SMQOL intervention had no significant effect on PEPPI total score (P = 0.226). We found a significant between-group difference in PEPPI total score in the anxiety group (P = 0.045), namely, the self-efficacy aspects of patient-physician communication of those with anxiety in the intervention group were better than for those in the control group after 4 months.

CONCLUSION

Use of the SMQOL had beneficial effects on communication self-efficacy between patients and physicians for outpatients with breast cancer, those with anxiety.

Perceptions of Japanese and Dutch women with early breast cancer about monitoring their quality of life

OBJECTIVE

Monitoring quality of life (QoL) in patients with cancer can provide insight into functional, psychological and social consequences associated with illness and its treatment. The primary objective of this study is to examine the influence of cultural factors on the communication between the patient and the health care provider and the perceived QoL in women with breast cancer in Japan and the Netherlands.

METHODS

In Japanese and Dutch women with early breast cancer, the number, content and frequency of QoL-related issues discussed at the medical encounter were studied. Patients completed questionnaires regarding QoL and evaluation of communication with the CareNoteBook.

RESULTS

The total number, frequency and content of QoL-related issues discussed differed between the two countries. Japanese women (n = 134) were significantly more reticent in discussing QoL-issues than the Dutch women (n = 70) (p < .001). Furthermore, Dutch patients perceived the CareNoteBook methodology significantly more positively than the Japanese patients (p < .001). Both groups supported the regular assessment via a CareNoteBook methodology.

CONCLUSIONS

Japanese women are more reluctant in expressing their problems with the illness, its treatment and patient-physician communication than Dutch women.

Parents' perspectives on nusinersen treatment for children with spinal muscular atrophy

AIM

To gain insight into parents' perspectives about their decision-making process concerning nusinersen treatment for their child, including perceived needs and concerns, and to explore factors that influence this process.

METHOD

This was an exploratory qualitative interview study among parents of children with spinal muscular atrophy types 1 to 3. Data were analysed using inductive thematic analysis.

RESULTS

Nineteen parents of 16 children representing 13 families participated. A wide variety of perspectives was reported ranging from a biomedical approach, which focused on battling the disease, to a holistic approach, which aimed for a good quality of life for their child. The most important factors that helped parents to decide were honest and neutral communication with their physician and access to available information.

INTERPRETATION

It is important physicians understand that there are different perspectives influencing the decision-making process. Physicians should create an environment that allows parents to accept or reject treatment by communicating honestly and openly with them and by discussing both options extensively. Clear information about pros and cons, recent developments in research, and the experiences of other parents should be made available to enable parents to make an informed decision. What this paper adds Parents perceived different needs and concerns about nusinersen treatment, which emphasized individual differences. Parents' perspectives varied from battling the disease to preserving quality of life. Life expectancy, stopping deterioration, and improving quality of life were the perceived benefits of nusinersen treatment. Open communication about the pros and cons of treatment with clinicians facilitated decision-making. Clear and honest information facilitated the alignment of values and goals.

Using a quality of life (QoL)-monitor: preliminary results of a randomized trial in Dutch patients with early breast cancer

Purpose

The diagnosis and treatment of cancer negatively affect patients’ physical, functional and psychological wellbeing. Patients’ needs for care cannot be addressed unless they are recognized by healthcare providers (HCPs). The use of quality of life (QoL) assessments with feedback to HCPs might facilitate the identification and discussion of QoL-topics.

Methods

113 patients with stage I–IIIB breast cancer treated with chemotherapy were included in this randomized controlled trial. Patients were randomly allocated to receive either usual care, or usual care with an intervention consisting of a QoL-monitor assessing QoL, distress and care needs before every chemotherapy cycle visit. Patients completed questionnaires regarding QoL, illness perceptions, self-efficacy, and satisfaction with communication. From the 2nd visit onwards, patients in the intervention arm and their HCPs received a copy of the QoL overview and results were shown in patients’ medical files. Audio-recordings and patients’ self-reports were used to investigate effects on communication, patient management and patient-wellbeing. A composite score for communication was calculated by summing the number of QoL-topics discussed during each consultation.

Results

Use of the QoL-monitor resulted in a higher communication score (0.7 topics increase per visit, p = 0.04), especially regarding the disease-specific and psychosocial issues (p < 0.01). There were no differences in patient management, QoL, illness perceptions or distress. Patients in the experimental arm (n = 60) had higher scores on satisfaction with communication (p < 0.05).

Conclusions

Use of a QoL-monitor during chemotherapy in patients with early breast cancer might result in a more frequent discussion of QoL-topics, associated with high levels of patients’ satisfaction.

Electronic supplementary material

The online version of this article (10.1007/s11136-020-02549-8) contains supplementary material, which is available to authorized users.

Illness Perceptions and Quality of Life in Patients with Non-Small-Cell Lung Cancer: A 3-Month Follow-Up Pilot Study

Purpose

Examine illness perceptions, functional health and quality of life of lung cancer patients throughout chemotherapy treatment.

Patients and Methods

Longitudinal design with baseline measure 12 days after the first chemotherapy and follow-up measure 3 months later, where illness perceptions (BIPQ), functional health, and quality of life (EORTC QLQ-C-30) were measured. A total of 21 patients with non-small-cell lung cancer took part. Non-parametric testing was performed given the pilot nature of the study and the associated relatively small sample size.

Results

Small to medium changes in illness perceptions and functional health between the two measurement points were detected, with both becoming more positive. More negative illness perceptions at the beginning of the treatment were associated with less functioning and lower quality of life at both beginning and end of treatment.

Conclusion

Addressing illness perceptions seems a clinically relevant approach in improving functioning and quality of life of patients with non-small-cell lung cancer.

Validity and Reliability of the Japanese Version of the 10-Item Perceived Efficacy in Patient-Physician Interactions (PEPPI-10) Scale in Breast Cancer Outpatients

The 10-item Perceived Efficacy in Patient-Physician Interactions (PEPPI-10) questionnaire was used as an indirect measure of the patients' perception of the strength of their therapeutic connection with their physician. The English version of the PEPPI-10 could serve as a valuable research tool for analyzing the relationship between patient and physician. The incidence of breast cancer is amongst the highest in Japan, and Patient Reported Outcome is often used as an outcome measure for breast cancer. It is particularly important to establish a strong patient-physician interaction for patients with breast cancer, since these patients require long-term treatment. We designed the present study to assess the reliability and validity of the Japanese version of the PEPPI-10 in female Japanese breast cancer outpatients. A cross-sectional study was performed at the Saitama Cancer Center, Japan. From August 2014 to August 2015, the Japanese versions of the PEPPI-10 that measure patient-perceived self-efficacy and the Brief Illness Perception Questionnaire (BIPQ) that measure illness perception were used for 92 breast cancer patients who received outpatient chemotherapy (mean age: 52.9 years, Cancer Stage I or Stage II : 82.6%, receiving adjuvant chemotherapy: 69.6%). We found that the Japanese version of the PEPPI-10 scale had a high coefficient of internal consistency (Cronbach's α coefficient, 0.83) for reliability, and concurrent validity analysis indicated that the utility of PEPPI-10 was moderately correlated with that of the BIPQ. In conclusion, the Japanese version of the PEPPI-10 is a useful tool that can empower breast cancer outpatients during the course of their treatment.

Black TiO2 nanotubes: Efficient electrodes for triggering electric field-induced stimulation of stem cell growth

TiO₂ nanostructures represent a key platform for biomedical applications, due to the combination of biocompatibility and high surface area. Especially TiO₂ nanotube layers have been widely investigated due to controllable nanotopographic effects as well as for electrodes in electrostimulation experiments. In the present work we produce Ar/H₂-reduced 'black' TiO₂ nanotube arrays with a strongly enhanced electrical conductivity and explore their interaction with mesenchymal stem cells when used as electrodes to apply electric fields (EF) across the cells. While we observe no significant change in cell adhesion and their focal contact formation on these high conductivity nanotubes, we do observe a rapid stem cell response when EF is engaged using the 'black' TiO₂ nanotube arrays as electrodes. Compared to as-formed nanotube arrays, a faster stem cell growth was observed and a lower EF intensity caused an intracellular calcium level elevation. Our results indicate that the increased conductivity in TiO₂ nanotubes significantly enhances the early stem cell response to minimal electric field stimuli. STATEMENT OF SIGNIFICANCE: The use of TiO₂ nanostructures in biomedical applications is widely investigated, especially considering the nanostructured surface influence on the biomaterial-cell interactions. We have previously shown that an applied electric field (EF) on stem cells grown on TiO₂ nanotubes leads to synergistic osteogenic stimulation in the absence of biochemical bone-inducing supplements. Here we report that black (i.e. highly conductive nanotubes obtained by reduction treatments) TiO₂ nanotubes enable short-time EF effects on stem cells: we observe a faster stem cell growth and a significantly enhanced early stem cell response to minimal EF stimuli. The application of such nanostructures under electric field is promising for therapeutic interventions for bone regeneration and tissue engineering approaches.

Participation and mental well-being of mothers of home-living patients with spinal muscular atrophy

Proximal spinal muscular atrophy (SMA) causes severe physical limitations but also has a major impact on the lives of parents. The aim of this study was to investigate participation and mental well-being (burden, emotional distress and satisfaction with participation) of parents of home-living patients with SMA. Caregiver burden was assessed with the Caregiver Strain Index, emotional distress with the Hospital Anxiety and Depression Scale and satisfaction with participation with the Utrecht Scale for Evaluation of Rehabilitation-Participation. Because the majority of parents were mothers of home-living SMA patients (76%), further analyses were restricted to mothers. Seventy-seven percent of mothers of patients with SMA had paid work. A substantial proportion of mothers (76%) perceived high caregiver burden. Burden, emotional distress and satisfaction with participation were comparable between mothers of children and mothers of adults with SMA. Caregivers' participation in leisure activities was significantly related to their perceived level of caregiver burden, emotional distress and satisfaction with participation. Mothers engaging in more social and leisure activities reported lower emotional distress and caregiver burden. Considering the high level of burden attention should be paid to mental well-being of primary caregivers of patients with SMA. Caregivers should be motivated to keep participating in social/leisure activities.

Psychological well-being in adults with spinal muscular atrophy: the contribution of participation and psychological needs

Purpose: Patients with spinal muscular atrophy (SMA) suffer from slowly progressive weakness of axial, respiratory and proximal muscles, leading to restrictions in activity and participation. This study aims to investigate patients' level of psychological well-being, using the International Classification of Functioning model and self-determination theory as theoretical frameworks.Materials and methods: In this cross-sectional study, adults with SMA were invited to complete a questionnaire. Instruments to assess psychological well-being included the Satisfaction with Life Scale, the Rosenberg Self-Esteem Scale and the Positive and Negative Affect Scale. Hierarchical lineal regression analyses were performed to investigate the contribution of participation (International Classification of Functioning model) and satisfaction of the need for autonomy, competence and relatedness (self-determination theory) to well-being.Results: Ninety-two respondents (67%) returned the questionnaire. Levels of psychological well-being were comparable to that of healthy reference samples. Well-being was unrelated to sociodemographic variables or illness characteristics. By contrast, well-being was closely related to respondents' satisfaction with participation, and their sense of autonomy, competence and relatedness.Conclusions: This study illustrates the relevance of psychological needs for understanding well-being of individuals with SMA. Supporting patients in meeting their psychological needs should become an objective of person-centred care for this population.Implications for rehabilitationSpinal muscular atrophy is a rare inherited disease, characterized by slowly progressive muscle weakness.Psychological well-being, including satisfaction with life, self-esteem and emotional functioning of adults with spinal muscular atrophy appears very comparable with that of healthy reference samples.In line with the International Classification of Functioning framework, well-being in adults with spinal muscular atrophy may be improved by increasing their (satisfaction with) participation.Moreover, clinical assessment and management should focus on optimizing patients' satisfaction with their basic psychological needs (autonomy, competence, relatedness), as this is strongly related to indices of psychological well-being.

Cross-cultural comparison of breast cancer patients' Quality of Life in the Netherlands and Japan

Purpose

Cultural differences are hypothesized to influence patients’ Quality of Life (QoL) reports. However, there is a lack of empirical cross-cultural studies comparing QoL of patients with cancer. This study aims to compare QoL of women with breast cancer in the Netherlands and Japan, and to investigate the association of QoL with sociodemographic, clinical, and psychological variables (illness perceptions).

Methods

Dutch (n = 116) and Japanese (n = 148) women with early breast cancer undergoing chemotherapy completed the EORTC QLQ-C30 and Brief Illness Perception Questionnaire immediately before their second cycle of chemotherapy.

Results

Dutch women reported poorer Physical, Role, Emotional, and Cognitive functioning than Japanese women. Additionally, illness perceptions were significantly different in Japan and the Netherlands, but these did not vary across treatment type. In Japan, QoL of women receiving AC-chemotherapy was better than that of women receiving FEC-chemotherapy, whereas in the Netherlands, QoL did not vary as a function of chemotherapy. Illness perceptions about symptom severity, adverse consequences, and emotional representations were negatively related to most domains of patients’ QoL in both countries. Adding illness perceptions as covariates to the ANOVA analyses rendered the effects of country and treatment type on QoL non-significant.

Conclusions

Comparing Dutch and Japanese women with early breast cancer revealed important differences in treatment modalities and illness perceptions which both appear to influence QoL. Perceptions about cancer have been found to vary across cultures, and our study suggests that these perceptions should be considered when performing cross-cultural studies focusing on patient-reported outcomes.

Illness Perceptions in Women with Breast Cancer-a Systematic Literature Review

Women with breast cancer respond to the illness and its medical management in their own personal way. Their coping behavior and self-management are determined by their views (cognitions) and feelings (emotions) about symptoms and illness: their illness perceptions. This paper reports the results of a systematic literature review of illness perceptions and breast cancer. In the 12 studies identified, published between 2012 and 2015, illness perceptions were found to be important concomitants of medical and behavioral outcomes: fear of recurrence, distress, quality of life, satisfaction with medical care, use of traditional healers, and risk perception. Intervention studies are called for where the effects are examined of replacing unhelpful illness perceptions by more constructive ones. Health care providers do well by incorporating illness perceptions in their care for women with breast cancer, as this is instrumental in improving patients’ quality of life.

Self-management in patients with COPD: theoretical context, content, outcomes, and integration into clinical care

In this narrative review, we put self-management in the context of a 50-year history of research about how patients with COPD respond to their illness. We review a definition of self-management, and emphasize that self-management should be combined with disease management and the chronic care model in order to be effective. Reviewing the empirical status of self-management in COPD, we conclude that self-management is part and parcel of modern, patient-oriented biopsychosocial care. In pulmonary rehabilitation programs, self-management is instrumental in improving patients' functional status and quality of life. We conclude by emphasizing how studying the way persons with COPD make sense of their illness helps in refining self-management, and thereby patient-reported outcomes in COPD.

Abstract OT3-1-03: DIRECT: A phase II/III randomized trial with dietary restriction as an adjunct to neoadjuvant chemotherapy for HER2-negative breast cancer

Background:

Preclinical evidence shows that short-term fasting protects normal cells, while cancer cells are sensitized to chemotherapy. Furthermore, a specifically designed very low calorie, low amino acid substitution diet (“Fasting Mimicking Diet”, FMD) has similar effects on chemotherapy as short-term fasting. This trial evaluates the impact of FMD on tolerance to and efficacy of neoadjuvant chemotherapy in women with HER2-negative early breast cancer.

Trial design:

DIRECT is a Dutch, randomized, open-label multicenter phase II/III trial. Women receiving neoadjuvant TAC courses (docetaxel/adriamycin/cyclophosphamide; day 1, q 3 weeks with G-CSF support at day 2) will be randomized with or without FMD for 3 days prior to and the day of chemotherapy and 3 days prior to surgery.

Eligibility criteria:

Eligible women are WHO 0-2, age ≥18 years, HER2-negative, stage II or III breast cancer and adequate bone marrow, liver and renal function, BMI &gt; 19kg/m2 and absence of diabetes mellitus.

Study endpoints:

The primary endpoints are grade III/IV toxicity (phase II) and the pathologic complete response rate (pCR) (phase III). Secondary endpoints are grade I/II toxicity, metabolic and inflammatory response to chemotherapy, DNA damage, apoptosis, immunology and nutrient sensing pathways in the tumor, biomarkers as single nucleotide polymorphisms, Ki67 and tumor stroma/ratio, patient's quality of life and (disease free) survival. Optional side studies include chemotherapy-induced DNA damage and nutrient sensing pathways in leukocytes and proteomics.

Statistical Methods:

Using a 5% significance level based on the two-sided Fisher's exact test with a power of 80%, 128 patients (64/arm) will be enrolled to show a 50% decrease of grade III/IV adverse events in the experimental arm (phase II) and 250 patients (125/arm) are needed to show an improvement of the pCR rate from 18% to 36% (phase III).

Target accrual:

Recruitment will start in September 2013. The expected end of accrual of 250 patients from multiple centers in the Netherlands will be the last quarter of 2015.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-1-03.

Development of a Decision Aid about fertility preservation for women with breast cancer in The Netherlands

OBJECTIVES

To improve information provision about fertility preservation for breast cancer patients in the Netherlands, a web-based Decision Aid (DA) with additional values clarification exercise was developed according to the International Patient Decision Aid Standards criteria. This study reports on development of the DA.

METHODS

Development consisted of four stages: (I) development of a draft DA, (II) acceptability of the draft DA to patients, (III) understanding (knowledge) in healthy populations, (IV) acceptability of the revised DA among patients and physicians. The study population consisted of 185 participants: 20 patients, 17 physicians and 148 healthy volunteers.

RESULTS

The draft DA was considered to be relevant and understandable by patients, physicians and healthy volunteers. The values clarification exercise needed adaptation in explanation and navigation, which was done after stage II. Knowledge scores improved by 18% for lower educated women (from 4.1 (41%) to 5.9 (59%) correct answers), and by 34% for higher educated women after viewing the website (from 3.9 (39%) to 7.3 (73%) correct answers). Design of the DA was evaluated to be clear, but not always very appealing.

CONCLUSIONS

The DA was regarded as a relevant source of information that seemed coherent and understandable.

From despair to hope: a longitudinal study of illness perceptions and coping in a psycho-educational group intervention for women with breast cancer

OBJECTIVES

This study examined the cross-sectional and longitudinal relationships of illness perceptions, coping, and distress in women with breast cancer. Illness perceptions and coping at baseline and changes in these variables over time served as possible predictors of distress at two follow-up points.

DESIGN AND METHODS

Fifty-seven women with breast cancer who participated in a psychosocial aftercare programme completed a questionnaire before the start of the intervention, directly after the end of the intervention, and 1 year after the start of the intervention. Study variables were assessed with the Illness Perception Questionnaire-Revised (illness perceptions), the COPE (coping), and the Hopkins Symptom Check List (distress).

RESULTS

Results showed that 43% of variance in distress at baseline was explained by participants' illness perceptions. Cyclical timeline perceptions were the strongest predictor of distress at baseline. Longitudinal data revealed that after the end of the intervention, the intensity of general distress and breast cancer-related emotions had decreased significantly. Partial correlations showed that baseline illness perceptions were unrelated to distress at follow-up. However, changes in illness perceptions (perceptions about the cyclical and chronic timeline and symptoms associated with breast cancer) showed significant associations with distress at both follow-up assessments. Associations of follow-up distress with coping styles were less consistent.

CONCLUSIONS

Our results suggest that changes in illness perceptions are related to an improvement or worsening of patients' emotional well-being over time. These findings hold promise for the development of interventions that specifically target patients' representations of their illness.

Concerns about exercise are related to walk test results in pulmonary rehabilitation for patients with COPD

Background

Although international guidelines on pulmonary rehabilitation acknowledge that psychological factors contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD), the few empirical studies investigating this association have found inconsistent results.

Purpose

The purpose of this study is to investigate whether negative affect and beliefs about exercise of patients with COPD would be related to baseline 6-min walk (6-MW) test results in a pulmonary rehabilitation setting, after correction for physical variables (sex, age, height, weight, and lung function). A second aim was to examine whether patients' beliefs are associated with treatment outcomes, as measured by an improvement in 6-MW distance.

Method

A 12-week pulmonary rehabilitation program was completed by 166 patients. Beliefs (perceived necessity and concerns) about exercise and negative affect were assessed by a questionnaire. Clinical data were obtained from medical records.

Results

Baseline 6-MW distance was positively related to younger age, male gender, better pulmonary function, and having fewer concerns about exercise. After rehabilitation, patients had increased their walk distance by 12% (32 m), on average. Baseline physiological and psychological variables were unrelated to patients' response to treatment (increase in walk distance). However, subgroup analysis showed that for patients with mild to moderate airflow obstruction, concerns about exercise were negatively related to response to treatment.

Conclusion

We conclude that patients' beliefs about the negative consequences of exercise are associated with baseline 6-MW test performance and response to treatment for patients with mild to moderate COPD. We recommend that patients' concerns about exercise are discussed and, if necessary, corrected during the intake phase.

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

Drop-out and attendance in pulmonary rehabilitation: the role of clinical and psychosocial variables

BACKGROUND

In spite of the well-demonstrated benefits for patients with COPD, pulmonary rehabilitation programmes show considerable drop-out and suboptimal attendance rates. The purpose of this prospective study is to examine causes for drop-out and non-attendance during a 12 week multidisciplinary pulmonary rehabilitation programme, and to investigate whether sociodemographic and medical factors as well as patients' perception of their illness are related to drop-out and non-attendance.

METHODS

Two hundred and seventeen patients with COPD who were referred to a rehabilitation centre participated in this multicentre study. Prior to treatment, patients received a questionnaire, which included the Illness Perception Questionnaire-Revised. Clinical data were drawn from medical records. Drop-out and attendance were recorded during the programme.

RESULTS

Fifty patients (23%) did not complete the rehabilitation course, of which half was due to medical reasons (e.g. exacerbations, hospitalisations). Non-completion could not be predicted by baseline sociodemographic, clinical or psychological variables. Patients who declined treatment did not differ from patients who dropped out due to medical reasons. On average, patients attended 92% of all scheduled appointments. Of all missed appointments, approximately 20% were accountable to factors beyond patients' control (e.g. absent therapists, hospitalisations). Smoking, living alone, a lower fat free mass and lower confidence in treatment increased the chance of patients not attending an appointment during rehabilitation.

CONCLUSION

In general, adherence in rehabilitation is high. However, paying attention to patients' nutritional status and creating a positive expectation of treatment during referral and intake appear to be important if one aims to optimise patients' attendance during rehabilitation.

Illness perceptions and COPD: an emerging field for COPD patient management

OBJECTIVE

Patients with chronic obstructive pulmonary disease have perceptions of their illness and its management that determine their coping behaviors (e.g., adherence, self-management) and, consequently, their outcomes. This article reviews the empirical literature on illness perceptions in patients with COPD to provide clinicians with information regarding the potential utility of incorporating illness perceptions into clinical COPD care.

METHOD

A literature search in PubMed identified 16 studies examining associations between illness perceptions and outcomes in patients with COPD.

RESULTS

Seven of the 16 papers were from US authors, followed by 3 each from the UK and The Netherlands, and one study each from Australia, Canada, and New Zealand. The first study was published in 1983, and the numbers of patients per study ranged fom 10 to 266. The illness perceptions were those delineated by two theoretical models (cognitive behavioral theory and the Common Sense Model), and they were assessed with open interviews and validated questionnaires. Outcomes were disability, quality of life, and psychological characteristics. The studies revealed clinically meaningful associations between illness perceptions and outcomes.

CONCLUSION

Our review supports the incorporation of illness perceptions into clinical care for patients with COPD. The assessment of illness perceptions should be routine, similar to routine assessments of pulmonary function. Discussing and changing illness perceptions will improve COPD patients' quality of life and reduce their levels of disability. COPD-specific assessments ("diagnosis") of illness perceptions and COPD-specific intervention methods ("therapy") that help change inadequate and maladaptive illness perceptions are research priorities.

Illness perceptions about asthma are determinants of outcome

This article reviews an emerging area of research on patients with asthma: namely, illness perceptions and their relationships with various aspects of outcome. The article briefly introduces the Common Sense Model, outlining the relevance of how "lay" patients conceptualize symptoms, illness, and treatment. On the basis of a comprehensive literature search, nine empirical studies illustrating the relationships between illness perceptions and outcomes are discussed. It is concluded that further research should focus on assessing asthma-specific illness and treatment beliefs. Also, given the effects of intervention studies in illness perceptions in other patient categories, it is recommended that serious consideration be given to intervention studies focusing on eliciting and changing illness perceptions in asthma patients, especially in those whose self-management seems to be inadequate.

Participation and drop-out in pulmonary rehabilitation: a qualitative analysis of the patient's perspective

OBJECTIVE

To examine patients' pretreatment beliefs and goals regarding pulmonary rehabilitation.

DESIGN

Qualitative study using semi-structured interviews.

SETTING

Interviews conducted at participants' homes.

SUBJECTS

Twelve patients with chronic obstructive pulmonary disease who had been referred to a rehabilitation clinic.

MAIN MEASURES

Patients' beliefs about pulmonary rehabilitation, self-set treatment goals and anticipated reasons for drop-out.

RESULTS

Patients' beliefs about pulmonary rehabilitation comprised positive aspects (participation as an opportunity for improvement, a safe and multidisciplinary setting, presence of motivating and supporting patients) and negative aspects of exercising in a rehabilitation centre (e.g. disruption of normal routine, being tired after training, transportation difficulties, limited privacy and confrontation with severely ill patients). Four types of treatment goals were formulated: increase in functional performance, weight regulation, reduction of dyspnoea, and improvement of psychosocial well being. Four clusters of anticipated reasons for drop-out were identified: the intensity of the programme, barriers to attending (e.g. transportation problems, sudden illness and other duties/responsibilities), lack of improvement and social factors. Four different attitudes towards pulmonary rehabilitation could be distinguished: optimistic, 'wait and see', sceptic and pessimistic. Follow-up data revealed that whereas a pessimistic attitude (high disability, low self-confidence, many concerns) was related to decline, the 'sceptic' patients had dropped out during the course.

CONCLUSIONS

Uptake and drop-out may be related to patients' perceived disabilities, expected benefits and concerns with regard to rehabilitation, practical barriers and confidence in their own capabilities.

Symptomatic reversible duodenal compression due to iatrogenic retroperitoneal hematoma

Selective serotonin reuptake inhibitors are frequently employed to treat depression. However, although rarely, coagulation abnormalities have been described following the use of these compounds, and these effects appear to be enhanced by simultaneous use of nonsteroidal anti-inflammatory drugs. We describe a case of reversible symptomatic duodenal compression caused by a retroperitoneal hematoma after ingestion of sertraline and nimesulide.

Exploring computational lead optimisation with affinity constants obtained by surface plasmon resonance for the interaction of PorA epitope peptides with antibody against Neisseria meningitidis

LUDI is a program used for de novo structure-based design of ligands and can predict binding of ligands quantitatively using a scoring function. Here we evaluate LUDI in a lead optimisation study with ligands for the antibody MN12H2, that has been raised against outer membrane protein PorA epitope P1.16 of Neisseria meningitidis. The ligands were synthetic peptides that are derived from the smallest binding epitope (182)DTNNN(186). LUDI's fragment building rules are used for the proposal of new peptide-ligands for MN12H2 and were focused on replacements of Asp(186) in the epitope. Accordingly, a series of peptides was synthesised with isosteric mutations. The interaction of the peptides with MN12H2 was analysed with a surface plasmon resonance competition assay yielding equilibrium binding constants in solution (K(S)). The binding affinity seems to be largely determined by entropy, and the side chain of Asn(186) is sensitive for charge, inversion, hydrophobicity and size. Head-to-tail cyclisation of the peptide in a nine-amino-acid ring gives little reduction in affinity. It is concluded that the scoring function of LUDI does not help in optimisation of the peptide lead for MN12H2 binding. Other more elaborate molecular mechanics calculations show similar results. This implies that our current knowledge of molecular recognition is insufficient for explaining a case of peptide-protein binding, where the design process requires subtle changes in structure (from lead finding to lead optimisation).

Bcl-2 mediates sex-specific differences in recovery of mice from LPS-induced signs of sickness independent of IL-6

Chronic pulmonary diseases are more common in boys than in girls. Therefore, we investigated the differences in signs of sickness in male and female mice that were exposed to lipopolysaccharide (LPS) by intranasal instillation. Because apoptosis is important in the resolution of inflammation, we tested the hypothesis that reduced levels of Bcl-2, a regulator of apoptosis, may play a role in gender-specific differences in response to inflammation. Bcl-2 wild-type (+/+) female mice recovered from an LPS-induced drop in body temperature and loss in body weight significantly faster than male (+/+) mice. Female heterozygous (+/-) mice showed reduced Bcl-2 levels and exhibited a slower recovery than female (+/+) mice that was similar to the recovery pattern in male (+/+) and (+/-) mice. Interleukin-6 (IL-6) activity levels in the bronchoalveolar lavage fluid were higher in male than in female mice but were not different between (+/+) and (+/-) mice. We conclude that Bcl-2 plays a role in mediating the faster recovery of female (+/+) mice from LPS-induced signs of sickness independent of IL-6. These studies indicate that apoptotic mechanisms may be involved in gender-specific differences in chronic pulmonary diseases.

Excitatory nicotinic and desensitizing muscarinic (M2) effects on C-nociceptors in isolated rat skin

The actions of different cholinergic agonists and antagonists were investigated on nociceptive afferents using the rat skin-saphenous nerve preparation, in vitro. Nicotine was able to weakly excite C-nociceptors and to induce a mild sensitization to heat stimulation (in 77% of tested fibers) in a dose-dependent manner (10(-)6 to 10(-)5 m), but it caused no alteration in mechanical responsiveness tested with von Frey hairs. Muscarine did not induce a significant nociceptor excitation, but almost all fibers exhibited a marked desensitization to mechanical and heat stimuli in a dose-dependent manner (from 10(-)6 to 10(-)4 m). The muscarinic effects could be prevented by the general muscarinic antagonist scopolamine (10(-)5 m), by the M3 antagonist 1,1-dimethyl-4-diphenylacetoxypiperidium oxide (10(-)6 m) co-applied with the M2 antagonist gallamine (10(-)5 m), and by gallamine alone. As positive control we used the relatively M2-selective agonist arecaidine (10(-)6 to 10(-)5 m), obtaining a similar desensitizing effect as with muscarine. Finally, we performed an immunocytochemical study that demonstrated the presence of M2 but not M3 receptors in thin epidermal nerve fibers of the rat hairy skin. Altogether, these data demonstrate opposite effects of nicotinic and muscarinic receptor stimulation on cutaneous nociceptors. M2 receptor-mediated depression of nociceptive responsiveness may convey a therapeutic, i.e., analgesic or antinociceptive, potential.

Peptoid - peptide hybrids that bind Syk SH2 domains involved in signal transduction

Peptoid-peptide hybrids are oligomeric peptidomimetics that contain one or more N-substituted glycine residues. In these hybrids, the side chains of one or several amino acids are "shifted" from the alpha-carbon atom to the amide nitrogen atom. A library of phosphorylated peptoid-peptide hybrids derived from the sequence pTyr-Glu-Thr-Leu was synthesized and tested for binding to the tandem SH2 domain of the protein tyrosine kinase Syk. A considerable influence of the side chain position was observed. Compounds 19-21, 24, and 25 comprising a peptoid NpTyr and/or NGlu residue did not show any binding. Compounds 22, 23, and 26 containing an NhThr (hThr=homothreonine) and/or NLeu peptoid residue showed binding with IC(50) values that were only five to eight times higher than that of the tetrapeptide lead compound 18. These data show that side chain shifting is possible with retention of binding capacity, but only at the two C-terminal residues of the tetramer. This method of a peptoid scan using peptoid-peptide hybrids appears to be very useful to explore to what extent a peptide sequence can be transformed into a peptoid while retaining its affinity.

Bcl-2 in LPS- and allergen-induced hyperplastic mucous cells in airway epithelia of Brown Norway rats

Environmental toxins, infection, and allergens lead to a transient mucous cell hyperplasia (MCH) in airway epithelia; however, the mechanisms for reducing mucous cell numbers during recovery are largely unknown. This study investigated Bcl-2 expression in mucous cells induced by a neutrophilic or eosinophilic inflammatory response. Brown Norway rats intratracheally instilled with lipopolysaccharide (LPS) showed an inflammatory response characterized primarily by neutrophils. Secreted mucin was increased fourfold at 1 day, and the number of mucous cells was increased fivefold 2, 3, and 4 days post-LPS instillation compared with those in noninstilled rats. None of the mucous cells in non- or saline-instilled control animals expressed Bcl-2, whereas 20-30% of mucous cells were Bcl-2 positive 1 and 2 days post-LPS instillation. Brown Norway rats immunized and challenged with ovalbumin (OVA) for 2, 4, and 6 days showed an inflammatory response characterized primarily by eosinophils. Secreted mucin increased fivefold, and mucous cell number increased fivefold after 4 and 6 days of OVA exposure compared with water-immunized control rats challenged with OVA aerosols. Approximately 10-25% of mucous cells were Bcl-2 positive in OVA-immunized and -challenged rats. These data demonstrate Bcl-2 expression in hyperplastic mucous cells of Brown Norway rats regardless of the type of inflammatory response and indicate that apoptotic mechanisms may be involved in the resolution of MCHs.

Kinetic analysis of the mass transport limited interaction between the tyrosine kinase lck SH2 domain and a phosphorylated peptide studied by a new cuvette-based surface plasmon resonance instrument

We explored the use of a newly developed cuvette-based surface plasmon resonance (SPR) instrument (IBIS) to study peptide-protein interactions. We studied the interaction between the SH2 domain of lck and a phosphotyrosine peptide EPQY*EEIPIYL which was immobilized on a sensor chip. No indications for mass transport limitation (MTL) were observed when standard kinetic approaches were used. However, addition of competing peptide during dissociation revealed a high extent of rebinding. A dissociation rate constant (k(d)) of 0.6+/-0.1 s(-1) was obtained in the presence of large amounts of peptide. A simple bimolecular binding model, applying second-order kinetics for the cuvette system, could not adequately describe the data. Fits were improved upon including a step in the model which describes diffusion of the SH2 domain from the bulk to the sensor, especially for a surface with high binding capacity. From experiments in glycerol-containing buffers, it appeared that the diffusion rate decreased with higher viscosity. It is demonstrated that MTL during association and dissociation can be described by the same diffusion rate. A binding constant (K(D)) of 5.9+/-0.8 nM was obtained from the SPR equilibrium signals by fitting to a Langmuir binding isotherm, with correction for loss of free analyte due to binding. An association rate constant k(a) of 1.1(+/-0.2)x10(8) M(-1) x s(-1) was obtained from k(d)/K(D). The values for k(a) and k(d) obtained in this way were 2-3 orders larger than that from standard kinetic analysis, ignoring MTL. We conclude that in a cuvette the extent of MTL is comparable to that in a flow system.

Mechanism of action of the nonlipophilic antiallergic drug eclazolast (REV 2871) in the inhibition of mediator release in a mast cell model

OBJECTIVE AND DESIGN

In this study, we compared eclazolast with other lipophilic antiallergic drugs, relating to effects on signal transduction pathways, leading to inhibition of exocytosis in a rat basophilic leukemia cell (RBL-2H3).

MATERIALS AND METHODS

Effects of the drugs on mediator release (beta-hexosaminidase, arachidonic acid metabolites) after Fc(epsilon)RI activation in RBL-2H3 cell were quantified. Furthermore, effects of the drugs on cellular signalling (Ca2+ influx, intracellular Ca2+ concentration, inositol 1,4,5-trisphosphate (IP3) concentration) were assayed. Effects of the drugs on bilayer and cell membranes have been recorded.

RESULTS

It is shown that eclazolast down-regulates IP3 levels. In contrast to lipophilic drugs, eclazolast does not affect artificial bilayers and erythrocyte membranes, and there is no effect on thapsigargin induced Ca2+ influx. The effect of eclazolast was highly dependent on the antigen concentration with which the cells were triggered.

CONCLUSIONS

The mechanism of action of eclazolast is deviant from lipophilic antiallergic agents. It inhibits exocytosis by intracellularly affecting only direct Fc(epsilon)RI linked processes and not through inhibition of Ca2+ influx channels, as found for membrane disturbing lipophilic drugs.

Influence of the antiallergic drug oxatomide and derivatives on membrane structures: relation with inhibition of calcium influx in rat basophilic leukemia cells

Oxatomide is an H1 antihistaminic drug that also inhibits mediator release from mast cells. From previous studies, it appeared that inhibition of the influx of extracellular calcium is the major cause of this inhibition of exocytosis. Here, we explored the role of drug-membrane interactions in the inhibition of mediator release. We investigated the effects on phase transition and fluidity of artificial membranes. All compounds studied distorted the phase transition in L-alpha-dipalmitoylphosphatidylcholine liposomes, which correlated with the drug-induced increase in membrane fluidity measured by fluorescence anisotropy of the bilayer interacting probe 1-[4-(trimethylamino)-phenyl]-6-phenylhexa-1,3,5-triene. Erythrocytes were used to study membrane effects on a cellular level. The hypotonic-induced haemolysis of erythrocytes was inhibited by the drugs. Compounds which increased membrane fluidity of liposomes to a greater extent were also more active in decreasing haemolysis. Drug-induced disturbance of the membranes is related to their effect on the activity of store-operated Ca2+ channels. The activity of these channels in rat basophilic leukemia cells, assayed as 45Ca2+ influx, was most effectively inhibited by oxatomide derivatives, thereby inducing a more rigid membrane structure. Small changes in molecular structure affect the activity of the drugs and these structure-activity relations are discussed.

Effects of oxatomide and derivatives on high affinity IgE receptor-activated signal transduction pathways in rat basophilic leukemia cells: role of protein tyrosine hyperphosphorylation and inhibition of extracellular calcium influx

The antiallergic drug oxatomide and analogs inhibit mediator release from a rat basophilic leukemia (RBL-2H3) cell line, which is frequently used as a mast cell model. By investigating a series of derivatives of oxatomide with different inhibiting activities on exocytosis, we aimed to evaluate the role of their effects on the early steps of the signal transduction cascade in the inhibition of exocytosis. The active compounds induced hyperphosphorylation of tyrosine residues both in stimulated as well as in resting cells. Furthermore, some elevation of the inositol 1,4,5-trisphosphate (IP3) formation upon antigen activation was observed for the active derivatives. Ca2+ fluxes were also studied. The inhibition of the antigen-induced 45Ca2+ influx correlated with the effects of the drugs on exocytosis. Furthermore, the inhibitory activity on antigen- and thapsigargin-mediated exocytosis correlated well. Adherence of the cells to fibronectin, stimulating cellular integrin receptors, was synergistic to antigen activation of the RBL cells. However, oxatomide did lack any effect on integrin-mediated processes, as the IC50 value for exocytosis was identical for fibronectin-adhered cells and standard cultured cells. We conclude that oxatomide and its analogs inhibit exocytosis, mainly by inhibiting Ca2+ influx over store-operated Ca2+ (SOC) channels. The drugs have a direct effect on the store-operated Ca2+ channels or affect the direct regulation of these channels.

Structure-activity relationships of astemizole derivatives for inhibition of store operated Ca2+ channels and exocytosis

The effects of a series of analogues of the antiallergic drug astemizole on the exocytosis of the enzyme beta-hexosaminidase were studied in a mast cell model, the rat basophilic leukemia (RBL-2H3) cell. Besides differences in the effects on Fc epsilonRI receptor-stimulated exocytosis, changes were also observed in Ca2+ influx and in the perturbation of the cell membrane. A strong correlation was found between the effects on antigen- and thapsigargin-stimulated 45Ca2+ influx. Furthermore, the inhibition of 45Ca2+ influx was correlated with the inhibition of beta-hexosaminidase release and membrane stabilization. It is concluded that the astemizole analogues are capable of inhibiting mast cell beta-hexosaminidase release through inhibition of Ca2+-store-operated Ca2+ channels (SOC). Compounds with high lipophilicity also released Ca2+ from intracellular stores. Lowering of the hydrophobicity by introduction of nitrogens or truncation at different sites in the astemizole structure decreased inhibitory activity on SOC channels. The inhibition of SOC channels cannot completely be ascribed to non-specific membrane effects. The piperidinyl-benzimidazole moiety was found to be important for inhibition of SOC channels. The observed differences in activity possibly depend on the way the compounds penetrate the membrane bilayer. Astemizole is an interesting new tool to study SOC channels and can be a lead for the design of mast cell-stabilizing antiallergic drugs.

Dual effect of the anti-allergic astemizole on Ca2+ fluxes in rat basophilic leukemia (RBL-2H3) cells: release of Ca2+ from intracellular stores and inhibition of Ca2+ release-activated Ca2+ influx

The antiallergic drugs astemizole and norastemizole inhibit exocytosis in mast cells, which might be relevant for their therapeutic action. From previous studies, it appeared that the drugs inhibited 45Ca2+ influx. Here, we present a more detailed study on the effects of astemizole and norastemizole on Ca2+ fluxes. Fura-2-loaded rat basophilic leukemia (RBL-2H3) cells were activated through the high-affinity receptor for IgE (FcepsilonRI) with antigen or by the endoplasmatic reticulum ATPase inhibitor thapsigargin, bypassing direct FcepsilonRI-related events. It appeared that astemizole (>15 microM), in contrast to norastemizole, showed a dual effect on intracellular calcium concentration ([Ca2+]i): a rise in intracellular calcium concentration was induced, which originated in the release of intracellular Ca2+ stores, whereas Ca2+ influx via store-operated Ca2+ (SOC) channels was inhibited. Ca2+ influx was further characterized using Ba2+ influx, whereas processes in the absence of Ca2+ influx were studied using Ni2+ or EGTA. It was concluded that the drugs most likely affect the store-operated Ca2+ channels in RBL cells directly. The two effects of astemizole on Ca2+ fluxes had opposing influences on exocytosis, thereby accounting for the biphasic effect of increasing astemizole concentration on mediator release in RBL cells.

Effects of the anti-allergics astemizole and norastemizole on Fc epsilon RI receptor-mediated signal transduction processes

The non-sedating anti-allergic drug astemizole, apart from its potential to antagonise H1 receptors, inhibits the release of inflammation mediators from mast cells. To study the mechanism of this inhibition, we investigated the effects of astemizole and one of its active metabolites, norastemizole, on different phases of Fc epsilon RI (the high affinity receptor for the immunoglobulin IgE) receptor-activated signal transduction in rat basophilic leukemia cells (RBL-2H3), leading to exocytosis. Cells were stimulated either through antigen, or thapsigargin, or synergistic combinations of Fc epsilon RI receptor activation with either adenosine A3 receptors or integrins, activated by fibronectin adherence. The effects of the drugs on mediator release, inositol 1,4,5-trisphosphate formation, tyrosine phosphorylation of cellular proteins and Ca2+ fluxes were investigated. Inositol 1,4,5-trisphosphate levels are not affected. Astemizole increased tyrosine phosphorylation in resting cells, especially a 96-kDa protein band. Particularly tyrosine phosphorylation related to post Ca2+ processes is changed after cell triggering in the presence of astemizole. Both drugs inhibit the influx of 45Ca2+, with similar dose response curves as for the inhibition of exocytosis. Astemizole but not norastemizole, when used in resting cells, released Ca2+ from intracellular stores. Astemizole (> 15 microM) also induced exocytosis in resting cells. It did not induce additional changes in its inhibiting effect when cells were triggered with synergistic combinations of Fc epsilon RI receptor activation with either adenosine A3 receptors or integrins. Effects on haemolysis of erythrocytes and differential scanning calorimetry in liposomes showed clear differences in membrane perturbation between astemizole and norastemizole. The observed differences, and the role of membrane perturbation in the action on Ca2+ fluxes, are discussed.

Relation between effects of a set of anti-allergic drugs on calcium pathways and membrane structure in Fc epsilon RI activated signal transduction

The antigen induced stimulation of mast cells by aggregation of Fc epsilon RI receptors activates a signal transduction cascade leading to release of mediators of inflammation like histamine, arachidonic acid metabolites and cytokines. In this study we investigated a series of structurally related anti-allergic drugs, containing a common lipophilic diphenylmethyl piperazinyl tail and head groups that differ in lipophilicity. Effects of these drugs on various steps of the signal transduction cascade was investigated to gain insight into the mechanism of action of these drugs. It appeared that addition of the drugs to resting cells induced changes in the tyrosine phosphorylation of cellular proteins. The most active anti-allergics in inhibiting exocytosis, AL3264 and oxatomide, also induced the largest changes in phosphorylation. The effects of the drugs on tyrosine phosphorylation after cell activation was complex. Additionally, Ca2+ fluxes were investigated. Ca2+ efflux from the cells was negligibly influenced by the active drugs. However, the drugs inhibited influx from extracellular Ca2+, which was correlated with the effects of the drugs on inhibition of exocytosis and on membrane stabilization induced by the drugs, measured as haemolysis of erythrocytes. It is concluded that inhibition of Ca2+ influx is the major mechanism with which these drugs inhibit exocytosis and that for this effect drug-membrane interactions, possibly affecting the function of membrane embedded proteins, are of importance. Possible mechanisms including drug-membrane interactions, phosphorylation and inhibition of Ca2+ influx are discussed.

Influence of the anti-allergic drug oxatomide on the signal transduction mechanism in a mast cell model

In a mast cell model, oxatomide displays inhibition of mediator release which is not related to its histamine H1 receptor antagonistic activity. From a previous study it appeared that especially early steps in the signal transduction leading to exocytosis were influenced by oxatomide. We now studied effects of oxatomide on those early steps in more detail. The antigen- and thapsigargin-mediated exocytosis in rat basophilic leukemia (RBL-2H3) cells were both inhibited by oxatomide. After aggregation of high affinity receptors for immunoglobulin E (Fc epsilon RI), protein tyrosine phosphorylation is induced. Oxatomide caused remarkable changes in the tyrosine phosphorylation pattern in resting cells. Also after antigen and thapsigargin activation, changes in the tyrosine phosphorylation of cellular proteins are observed. In addition, Ca2+ fluxes were studied by means of the net influx of 45Ca2+ and by measuring intracellular free Ca2+ concentrations ([Ca2+]) with the fluorescent probe fura-2. Oxatomide inhibited the 45Ca2+ influx and the increase in [Ca2+]i upon antigen and thapsigargin activation of the cells. Neither the release of Ca2+ from internal stores nor the efflux of Ca2+ over the plasma membrane seems to be affected. The effect of oxatomide on Ca2+ influx was further characterized by studying Ba2+ influx in the absence of extracellular free Ca2+. We conclude that inhibition of mediator release is mainly caused by inhibition of influx of extracellular Ca2+, via plasma membrane Ca2+ channels that are activated by depletion of intracellular Ca2+ stores. The molecular mechanism with which oxatomide might interfere with these channels is discussed.

Oxatomide and derivatives as inhibitors of mediator release from a mast cell model. Structure-activity relationships

A series of benzimidazolone and benzimidazole analogues of the antiallergic drug oxatomide (1-¿3-[4-(diphenylmethyl)-1-piperazinyl]propyl¿-1,3-dihydro-2H- benzimidazol-2-one, CAS 60607-34-3) [formula: see text], was evaluated for inhibiting the release of the performed mediator beta-hexosaminidase from the rat basophilic leukemia (RBL-2H3) cell line. Activation of the cells was induced by antigen, or by the calcium ionophore A23187 (calcimycin) in combination with or without the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). For the active compounds, inhibition of exocytosis was found with all triggers, with the antigen trigger being somewhat more sensitive. This indicates that the compounds influence several steps in the signal transduction route leading to exocytosis. The activity of the compounds is not totally aspecific as small structural changes strongly affect the inhibiting activity. Introduction of a chlorine substituent at the 6-position of the benzimidazolone group results in loss of activity. There does not seem to be a significant activity difference between the benzimidazolone and benzimidazole analogues. Analogues with n < 3, n > 5 or a branched alkyl chain between the piperazinyl and the benzimidazol(on)e moiety lose inhibitory activity. Secretion of the newly formed mediator arachidonic acid and its metabolites was affected by the compounds comparable to the effect on the release of beta-hexosaminidase. The anti-allergic activity did not correlate with the histamine H1-receptor antagonistic activity.

Inhibition of mediator release in RBL-2H3 cells by some H1-antagonist derived anti-allergic drugs: relation to lipophilicity and membrane effects

In a model for mucosal mast cells (RBL-2H3 cells) a set H1-antagonist derived anti-allergic drugs containing a diphenylmethyl piperazinyl moiety was examined for their ability to inhibit release of the mediator beta-hexosaminidase. Cells were activated with antigen or the calcium ionophore A23187, whether or not in combination with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Oxatomide, hydroxyzine and cetirizine inhibit the antigen induced beta-hexosaminidase release. The release triggered by A23187, whether or not in combination with TPA is hardly influenced by the compounds. A biphasic dependence of the inhibition of exocytosis in RBL cells on lipophilicity is observed with the optimum at log P is 5-6. The extremely lipophilic compounds meclozine and buclizine are not active in this model. pH dependence of the effect of the drugs shows that especially the uncharged species are active in inhibiting exocytosis. The investigated compounds show an effect on phase transitions in L-alpha-phosphatidylcholine dipalmitoyl liposomes as assayed with differential scanning calorimetry (DSC). For the less extremely lipophilic compounds the induced changes in the phospholipid membranes increased with lipophilicity. The relation between structural features of the drug and the interaction with phospholipids is discussed in view of the DSC results. We conclude that location of the active drugs at the membrane or the membrane/protein interface is important for the inhibiting activity on exocytosis. This could affect several membrane related processes, which are abundant in the early phases of the IgE-mediated signal transduction process.

Kinetic evaluation of the oxidation of phenothiazine derivatives by methemoglobin and horseradish peroxidase in the presence of hydrogen peroxide. Implications for the reaction mechanisms

The oxidation of ten 2-substituted 10-(3-(dimethylamino)propyl) phenothiazines (PHs) by methemoglobin (metHb) and horseradish peroxidase (HRP) in the presence of H2O2 was kinetically analysed based on an enzymic-chemical second-order reaction with substrate regeneration: PHs are oxidized enzymatically to their radical cations (PH+) which subsequently, in a second order reaction, react further to parent compound and PH-sulfoxide (PHSO). The enzymic reaction rate can be obtained from the accumulation curves of both radical cation formation and sulfoxide formation. In the case of chlorpromazine and promazine both methods gave similar reaction rates. The rate constant of PH+. decay could also be determined from the radical concentrations of their radicals. The rate constant of reaction of PHs with HRP compound II was also analysed. The logarithm of this rate constant correlated well with the Hammett sigma para and the Swain and Lupton F and R substituent constants, whereas no correlation with hydrophobic and steric parameters was found. This indicates that the interaction of PH with the porphyrin ring, which is the active site of HRP, is predominantly under electronic control. In the case of catalysis by hemoglobin (Hb), the formation of the reactive Hb form, ferry1Hb with a protein radical, appeared to be rate limiting in the oxidation of PHs by metHb-H2O2. Differences in the conversion rates of various PHs can be explained by a competition between their electron transfer reaction to the protein radical and the denaturation reaction(s) involving the protein radical. Our results confirm our earlier observation that the mechanism of oxidation by metHb-H2O2 differs from that of the classical peroxidases. In the former case, electron transfer from PH occurs most likely to a tyrosine residue on the globin part, whilst in the latter case electron transfer to the porphyrin moiety takes place.

The uptake of the trypanocidal drug suramin in combination with low-density lipoproteins by Trypanosoma brucei and its possible mode of action

In plasma, a significant part of suramin circulates in tight association with low-density lipoproteins (LDL). At therapeutically obtainable concentrations (100 microM) of suramin, about 85% of the total amount of the drug was bound to proteins, approximately 15% of which was bound to LDL. The molar ratio of suramin bound to LDL in serum was 7.5. The capacity of the high-affinity binding sites of LDL were 6.6 x 10(6) M-1, both in Tris buffer and in ultrafiltrate of serum. Suramin (100 microM) decreased the uptake of host LDL through receptor-mediated endocytosis by Trypanosoma brucei, with approximately 50%. LDL served as the only carrier for suramin uptake. Serum albumin, another important carrier for suramin in blood, was not able to promote suramin uptake, neither was delipidified plasma. The suramin taken up by T. brucei was recovered, in part, in the lysosomal fractions. It is suggested that deprivation of the parasite from cholesterol and phospholipids by an inhibition of the uptake of LDL, contributes to the mode of action of suramin, in addition to the many other effects that the drug may exert on the parasite. The toxic side-effects of suramin on the host are discussed in the light of its association with circulating lipoproteins.

Steroid binding to human serum albumin and fragments thereof. Role of protein conformation and fatty acid content

The binding properties of the steroids testosterone and pregnenolone to human serum albumin (HSA) and derived fragments of albumin have been investigated by means of equilibrium dialysis and circular dichroism. The 46 kDa peptic fragment (P46) of HSA comprises domains one and two of the HSA structure, whereas the other fragment, the 45 kDa tryptic fragment (T45) is composed of domains two and three. A comparison of the binding behaviour of the steroid ligands to HSA and its fragments showed that the single primary testosterone binding site in all probability is located in the second domain of the HSA molecule. For pregnenolone it was found that at least two primary binding sites are present, also located in domain two. Both steroids show pH dependent binding profiles in the case of HSA and the P46 fragment. The binding of the steroids to the T45 fragment seems to be pH independent. The same phenomenon was observed with the circular dichroism experiments, indicating a link between the steroid binding properties and the structural behaviour of the proteins. In fact, the binding properties of the steroids can be assigned to the neutral-to-base (N-B) transition. The possible role of fatty acids as modulators in the transport processes of steroids in the body is discussed.