Positive and negative outcomes of informal caregiving at home and in institutionalised long-term care: a cross-sectional study.

BACKGROUND: Our ageing society is putting tremendous strain on public health and welfare programs to meet the needs of ageing individuals. Promoting informal caregiving is one way for policymakers to reduce this burden. However, caregiving may be experienced as stressful and is associated with adverse health consequences. While quite a lot of research focuses on caregiving for community-dwelling older adults, little is known about informal care in institutionalised long-term care (ILTC). Therefore, the objectives of this study were: 1) to compare characteristics of informal caregivers and care receivers and caregiver outcomes - at home and in ILTC; 2) to study the association between these characteristics and positive and negative caregiver outcomes; 3) to investigate the moderating effect of the setting (at home vs. ILTC) on these associations. METHODS: A cross-sectional study was conducted using the TOPICS-MDS DataSet. A total of 5197 Dutch dyads were included. The average age of the care receivers and caregivers was respectively 80.7 years and 63.2 years. Several sociodemographic, health-related and caregiving-related characteristics of care receiver and caregiver and two caregiver outcomes (i.e., subjective burden and care-related quality of life) were included in the analyses. RESULTS: Caregivers in both settings experienced comparable levels of subjective burden. Caregivers at home had slightly lower care-related quality of life than caregivers in ILTC. Several care receiver characteristics (i.e., male sex, married/cohabiting, more morbidities/disability, and less self-perceived health/psychological wellbeing) and several caregiver characteristics (i.e., female sex, being younger, living together with the care receiver, more objective burden, less self-perceived health, and more support) were associated with an increase in burden and/or a decrease in care-related quality of life. Some of these associations were stronger for dyads at home compared to dyads in ILTC. CONCLUSIONS: Informal caregiving does not stop with admission to an ILTC facility. Both settings need an informal caregiving policy, which is (1) tailored to the individual characteristics of care receivers and caregivers; (2) pays attention to the identified risk groups; and (3) reduces the negative caregiver outcomes and emphasizes the positive outcomes at the same time.

Molecular View on Supramolecular Chain and Association Dynamics.

The chain and association dynamics of supramolecular polymer ensembles decisively determines their properties. Using neutron spin echo (NSE) spectroscopy we present molecular insight into the space and time evolution of this dynamics. Studying a well characterized ensemble of linearly associating telechelic poly(ethylene glycol) melts carrying triple H-bonding end groups, we show that H-bond breaking significantly impacts the mode spectrum of the associates. The breaking affects the mode contributions and not the relaxation times as was assumed previously. NSE spectra directly reveal the so far intangible H-bond lifetimes in the supramolecular melt and demonstrate that for both the microscopic and the macroscopic dynamics of the supramolecular ensemble the instantaneous average of the M_{w} distribution governs the system response at least as long as the Rouse picture applies.

MiR-193b promotes autophagy and non-apoptotic cell death in oesophageal cancer cells.

BACKGROUND: Successful treatment of oesophageal cancer is hampered by recurrent drug resistant disease. We have previously demonstrated the importance of apoptosis and autophagy for the recovery of oesophageal cancer cells following drug treatment. When apoptosis (with autophagy) is induced, these cells are chemosensitive and will not recover following chemotherapy treatment. In contrast, when cancer cells exhibit only autophagy and limited Type II cell death, they are chemoresistant and recover following drug withdrawal. METHODS: MicroRNA (miRNA) expression profiling of an oesophageal cancer cell line panel was used to identify miRNAs that were important in the regulation of apoptosis and autophagy. The effects of miRNA overexpression on cell death mechanisms and recovery were assessed in the chemoresistant (autophagy inducing) KYSE450 oesophageal cancer cells. RESULTS: MiR-193b was the most differentially expressed miRNA between the chemosensitive and chemoresistant cell lines with higher expression in chemosensitive apoptosis inducing cell lines. Colony formation assays showed that overexpression of miR-193b significantly impedes the ability of KYSE450 cells to recover following 5-fluorouracil (5-FU) treatment. The critical mRNA targets of miR-193b are unknown but target prediction and siRNA data analysis suggest that it may mediate some of its effects through stathmin 1 regulation. Apoptosis was not involved in the enhanced cytotoxicity. Overexpression of miR-193b in these cells induced autophagic flux and non-apoptotic cell death. CONCLUSION: These results highlight the importance of miR-193b in determining oesophageal cancer cell viability and demonstrate an enhancement of chemotoxicity that is independent of apoptosis induction.

Effectiveness of a home-based cognitive behavioral program to manage concerns about falls in community-dwelling, frail older people: results of a randomized controlled trial.

BACKGROUND: Concerns about falls are common among older people. These concerns, also referred to as fear of falling, can have serious physical and psychosocial consequences, such as functional decline, increased risk of falls, activity restriction, and lower social participation. Although cognitive behavioral group programs to reduce concerns about falls are available, no home-based approaches for older people with health problems, who may not be able to attend such group programs are available yet. The aim of this study was to assess the effectiveness of a home-based cognitive behavioral program on concerns about falls, in frail, older people living in the community. METHODS: In a randomized controlled trial in the Netherlands, 389 people aged 70 years and older, in fair or poor perceived health, who reported at least some concerns about falls and related activity avoidance were allocated to a control (n = 195) or intervention group (n = 194). The intervention was a home-based, cognitive behavioral program consisting of seven sessions including three home visits and four telephone contacts. The program aims to instill adaptive and realistic views about fall risks via cognitive restructuring and to increase activity and safe behavior using goal setting and action planning and was facilitated by community nurses. Control group participants received usual care. Outcomes at 5 and 12 months follow-up were concerns about falls, activity avoidance due to concerns about falls, disability and falls. RESULTS: At 12 months, the intervention group showed significant lower levels of concerns about falls compared to the control group. Furthermore, significant reductions in activity avoidance, disability and indoor falls were identified in the intervention group compared with the control group. Effect sizes were small to medium. No significant difference in total number of falls was noted between the groups. CONCLUSIONS: The home-based, cognitive behavioral program significantly reduces concerns about falls, related activity avoidance, disability and indoor falls in community-living, frail older people. The program may prolong independent living and provides an alternative for those people who are not able or willing to attend group programs. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01358032. Registered 17 May 2011.

Lysosomal Sequestration Determines Intracellular Imatinib Levels.

The intracellular uptake and retention (IUR) of imatinib is reported to be controlled by the influx transporter SLC22A1 (organic cation transporter 1). We recently hypothesized that alternative uptake and/or retention mechanisms exist that determine intracellular imatinib levels. Here, we systematically investigate the nature of these mechanisms. Imatinib uptake in cells was quantitatively determined by liquid chromatography-tandem mass spectrometry. Fluorescent microscopy was used to establish subcellular localization of imatinib. Immunoblotting, cell cycle analyses, and apoptosis assays were performed to evaluate functional consequences of imatinib sequestration. Uptake experiments revealed high intracellular imatinib concentrations in HEK293, the leukemic cell lines K562 and SD-1, and a gastrointestinal stromal tumor cell line GIST-T1. We demonstrated that imatinib IUR is time-, dose-, temperature-, and energy-dependent and provide evidence that SLC22A1 and other potential imatinib transporters do not substantially contribute to the IUR of imatinib. Prazosin, amantadine, NH4Cl, and the vacuolar ATPase inhibitor bafilomycin A1 significantly decreased the IUR of imatinib and likely interfere with lysosomal retention and accumulation of imatinib. Costaining experiments with LysoTracker Red confirmed lysosomal sequestration of imatinib. Inhibition of the lysosomal sequestration had no effect on the inhibition of c-Kit signaling and imatinib-mediated cell cycle arrest but significantly increased apoptosis in imatinib-sensitive GIST-T1 cells. We conclude that intracellular imatinib levels are primarily determined by lysosomal sequestration and do not depend on SLC22A1 expression.

miR-634 restores drug sensitivity in resistant ovarian cancer cells by targeting the Ras-MAPK pathway.

BACKGROUND: Drug resistance hampers the efficient treatment of malignancies, including advanced stage ovarian cancer, which has a 5-year survival rate of only 30 %. The molecular processes underlying resistance have been extensively studied, however, not much is known about the involvement of microRNAs. METHODS: Differentially expressed microRNAs between cisplatin sensitive and resistant cancer cell line pairs were determined using microarrays. Mimics were used to study the role of microRNAs in drug sensitivity of ovarian cancer cell lines and patient derived tumor cells. Luciferase reporter constructs were used to establish regulation of target genes by microRNAs. RESULTS: MiR-634 downregulation was associated with cisplatin resistance. Overexpression of miR-634 affected cell cycle progression and enhanced apoptosis in ovarian cancer cells. miR-634 resensitized resistant ovarian cancer cell lines and patient derived drug resistant tumor cells to cisplatin. Similarly, miR-634 enhanced the response to carboplatin and doxorubicin, but not to paclitaxel. The cell cycle regulator CCND1, and Ras-MAPK pathway components GRB2, ERK2 and RSK2 were directly repressed by miR-634 overexpression. Repression of the Ras-MAPK pathway using a MEK inhibitor phenocopied the miR-634 effects on viability and chemosensitivity. CONCLUSION: miR-634 levels determine chemosensitivity in ovarian cancer cells. We identify miR-634 as a therapeutic candidate to resensitize chemotherapy resistant ovarian tumors.

Change in quality of life of people with dementia recently admitted to long-term care facilities.

AIM: To assess which factors are associated with change in quality of life of people with dementia who have recently been admitted to long-term care facilities. BACKGROUND: Many people with dementia will be admitted to long-term care facilities at some point during their disease. It is currently unknown which factors are associated with improvement and/or deterioration of quality of life immediately following admission. DESIGN: An observational and longitudinal survey. METHODS: Data on 343 people with dementia who have been recently admitted to long-term care facilities across eight European countries were collected between November 2010-April 2012. Quality of life was assessed by people with dementia and their proxies using the 'Quality of Life-Alzheimer's Disease scale'. Explanatory variables included cognitive status, comorbidities, activities of daily living, depressive symptoms and neuropsychiatric symptoms. Descriptive and multilevel regression analyses were performed. RESULTS: Better cognitive abilities at baseline were associated with a decrease in self-reported quality of life. Greater dependency and more depressive symptoms at baseline were associated with declined proxy-reported quality of life. Furthermore, an increased dependency and an increase of depressive symptoms between baseline and follow-up were associated with a decreased proxy-reported quality of life. On an individual level, three groups were identified, namely people whose quality of life: (1) decreased; (2) stayed the same; and (3) increased. CONCLUSION: Cognitive functioning, functional rehabilitation and treatment of depressive symptoms should receive special attention. However, quality of life of people with dementia does not necessarily decrease after institutionalization.

MicroRNA expression profiles distinguish liposarcoma subtypes and implicate miR-145 and miR-451 as tumor suppressors.

Liposarcomas are rare, heterogeneous and malignant tumors that can be divided into four histological subtypes with different characteristics and clinical behavior. Treatment consists of surgery in combination with systemic chemotherapy, but nevertheless mortality rates are high. More insight into the biology of liposarcoma tumorigenesis is needed to devise novel therapeutic approaches. MicroRNAs (miRNAs) have been associated with carcinogenesis in many tumors and may function as tumor suppressor or oncogene. In this study we examined miRNA expression in an initial series of 57 human liposarcomas (including all subtypes), lipomas and normal fat by miRNA microarrays. Supervised hierarchical clustering of the most differentially expressed miRNAs (p < 0.0002) distinguished most liposarcoma subtypes and control tissues. The distinction between well differentiated liposarcomas and benign lipomas was blurred, suggesting these tumor types may represent a biological continuum. MiRNA signatures of liposarcoma subtypes were established and validated in an independent series of 58 liposarcomas and control tissues. The expression of the miR-143/145 and miR-144/451 cluster members was clearly reduced in liposarcomas compared to normal fat. Overexpression of miR-145 and miR-451 in liposarcoma cell lines decreased cellular proliferation rate, impaired cell cycle progression and induced apoptosis. In conclusion, we show that miRNA expression profiling can be used to discriminate liposarcoma subtypes, which can possibly aid in objective diagnostic decision making. In addition, our data indicate that miR-145 and miR-451 act as tumor suppressors in adipose tissue and show that re-expression of these miRNAs could be a promising therapeutic strategy for liposarcomas.

Transcutaneous sentinel lymph node detection in skin melanoma with near-infrared fluorescence imaging using indocyanine green.

The aim of the study is to assess whether indocyanine green (ICG) fluorescence can replace technetium in the preoperative detection of sentinel lymph nodes (SLN) from cutaneous melanoma. The current golden standard for SLN detection is the radioisotope technetium. A promising alternative is fluorescence imaging (FLI) using ICG. In this study, we enrolled patients undergoing sentinel lymph node biopsy (SLNB) for skin melanoma at the Erasmus Medical Center between November 2022 and July 2023. The SLNB procedure was performed as a standard of care. After general anesthesia, ICG was injected intradermally around the primary tumor site. Both the patient and the surgeon were not blinded for the location of the SLN. FLI was performed before incision, in vivo after incision, and ex vivo. Fluorescent SLNs were confirmed using the gamma probe in all cases. Thirty-two patients were included in this study, and a total of 39 SLNs were harvested. The transcutaneous detection rate of ICG was 21.9%. The combined ex vivo ICG fluorescence and technetium uptake was 94.9%. One SLN contained only ICG (2.6%) and one SLN contained only technetium-uptake (2.6%). FLI using ICG resulted in a relatively low transcutaneous detection, which means that exclusive use of this technique in its present form is not feasible. However, we did find a high accumulation of ICG in the SLN, indicating the potential of ICG in combination with other imaging techniques.

miRNA expression profiling of 51 human breast cancer cell lines reveals subtype and driver mutation-specific miRNAs.

INTRODUCTION: Breast cancer is a genetically and phenotypically complex disease. To understand the role of miRNAs in this molecular complexity, we performed miRNA expression analysis in a cohort of molecularly well-characterized human breast cancer cell lines to identify miRNAs associated with the most common molecular subtypes and the most frequent genetic aberrations. METHODS: Using a microarray carrying LNA™ modified oligonucleotide capture probes), expression levels of 725 human miRNAs were measured in 51 breast cancer cell lines. Differential miRNA expression was explored by unsupervised cluster analysis and was then associated with the molecular subtypes and genetic aberrations commonly present in breast cancer. RESULTS: Unsupervised cluster analysis using the most variably expressed miRNAs divided the 51 breast cancer cell lines into a major and a minor cluster predominantly mirroring the luminal and basal intrinsic subdivision of breast cancer cell lines. One hundred and thirteen miRNAs were differentially expressed between these two main clusters. Forty miRNAs were differentially expressed between basal-like and normal-like/claudin-low cell lines. Within the luminal-group, 39 miRNAs were associated with ERBB2 overexpression and 24 with E-cadherin gene mutations, which are frequent in this subtype of breast cancer cell lines. In contrast, 31 miRNAs were associated with E-cadherin promoter hypermethylation, which, contrary to E-cadherin mutation, is exclusively observed in breast cancer cell lines that are not of luminal origin. Thirty miRNAs were associated with p16INK4 status while only a few miRNAs were associated with BRCA1, PIK3CA/PTEN and TP53 mutation status. Twelve miRNAs were associated with DNA copy number variation of the respective locus. CONCLUSION: Luminal-basal and epithelial-mesenchymal associated miRNAs determine the subdivision of miRNA transcriptome of breast cancer cell lines. Specific sets of miRNAs were associated with ERBB2 overexpression, p16INK4a or E-cadherin mutation or E-cadherin methylation status, which implies that these miRNAs may contribute to the driver role of these genetic aberrations. Additionally, miRNAs, which are located in a genomic region showing recurrent genetic aberrations, may themselves play a driver role in breast carcinogenesis or contribute to a driver gene in their vicinity. In short, our study provides detailed molecular miRNA portraits of breast cancer cell lines, which can be exploited for functional studies of clinically important miRNAs.

Improving diagnosis and risk stratification across the ejection fraction spectrum: the Maastricht Cardiomyopathy registry.

AIMS: Heart failure (HF) represents a clinical syndrome resulting from different aetiologies and degrees of heart diseases. Among these, a key role is played by primary heart muscle disease (cardiomyopathies), which are the combination of multifactorial environmental insults in the presence or absence of a known genetic predisposition. The aim of the Maastricht Cardiomyopathy registry (mCMP-registry; NCT04976348) is to improve (early) diagnosis, risk stratification, and management of cardiomyopathy phenotypes beyond the limits of left ventricular ejection fraction (LVEF). METHODS AND RESULTS: The mCMP-registry is an investigator-initiated prospective registry including patient characteristics, diagnostic measurements performed as part of routine clinical care, treatment information, sequential biobanking, quality of life and economic impact assessment, and regular follow-up. All subjects aged ≥16 years referred to the cardiology department of the Maastricht University Medical Center (MUMC+) for HF-like symptoms or cardiac screening for cardiomyopathies are eligible for inclusion, irrespective of phenotype or underlying causes. Informed consented subjects will be followed up for 15 years. Two central approaches will be used to answer the research questions related to the aims of this registry: (i) a data-driven approach to predict clinical outcome and response to therapy and to identify clusters of patients who share underlying pathophysiological processes; and (ii) a hypothesis-driven approach in which clinical parameters are tested for their (incremental) diagnostic, prognostic, or therapeutic value. The study allows other centres to easily join this initiative, which will further boost research within this field. CONCLUSIONS: The broad inclusion criteria, systematic routine clinical care data-collection, extensive study-related data-collection, sequential biobanking, and multi-disciplinary approach gives the mCMP-registry a unique opportunity to improve diagnosis, risk stratification, and management of HF and (early) cardiomyopathy phenotypes beyond the LVEF limits.

Four miRNAs associated with aggressiveness of lymph node-negative, estrogen receptor-positive human breast cancer.

In this study, we quantified 249 mature micro-RNA (miRNA) transcripts in estrogen receptor-positive (ER(+)) primary breast tumors of patients with lymph node-negative (LNN) disease to identify miRNAs associated with metastatic capability. In addition, the prognostic value of the candidate miRNAs was determined in ER(-)/LNN breast cancer. Unsupervised analysis in a prescreening set of 38 patients identified three subgroups predominantly driven by three miRNA signatures: an ER-driven luminal B-associated miRNA signature, a stromal miRNA signature, and an overexpressed miRNA cluster located on chromosome 19q23, but these intrinsic miRNA signatures were not associated with tumor aggressiveness. Supervised analysis in the initial subset and subsequent analysis in additional tumors significantly linked four miRNAs (miR-7, miR-128a, miR-210, and miR-516-3p) to ER(+)/LNN breast cancer aggressiveness (n = 147) and one miRNA (miR-210) to metastatic capability in ER(-)/LNN breast cancer (n = 114) and in the clinically important triple-negative subgroup (n = 69) (all P < 0.05). Bioinformatic analysis coupled miR-210 to hypoxia/VEGF signaling, miR-7 and miR-516-3p to cell cycle progression and chromosomal instability, and miR-128a to cytokine signaling. In conclusion, our work connects four miRNAs to breast cancer progression and to several distinct biological processes involved therein.

One-step inkjet printing of conductive silver tracks on polymer substrates.

A one-step process to fabricate conductive features on flexible polymer substrates by inkjet printing an organometallic silver ink directly onto a substrate that is heated to 130 degrees C is presented. This process led to the immediate sintering of the printed features. The samples were left for 5 min at elevated temperature, which resulted in conductive silver features with a resistivity of eight times the bulk silver value. The combination of this ink and the simultaneous printing/sintering process opens up routes for the direct fabrication of conductive features on common polymer substrates that could be applied, for example, in roll-to-roll production of flexible microelectronic systems.

How dangerousness evolves after court-ordered compulsory psychiatric admission: explorative prospective observational cohort study.

BACKGROUND: Compulsory admission is commonly regarded as necessary and justified for patients whose psychiatric condition represents a severe danger to themselves and others. However, while studies on compulsory admissions have reported on various clinical and social outcomes, little research has focused specifically on dangerousness, which in many countries is the core reason for compulsory admission.AimsTo study changes in dangerousness over time in adult psychiatric patients admitted by compulsory court order, and to relate these changes to these patients' demographic and clinical characteristics. METHOD: In this explorative prospective observational cohort study of adult psychiatric patients admitted by compulsory court order, demographic and clinical data were collected at baseline. At baseline and at 6 and 12 month follow-up, dangerousness was assessed using the Dangerousness Inventory, an instrument based on the eight types of dangerousness towards self or others specified in Dutch legislation on compulsory admissions. We used descriptive statistics and logistic regression to analyse the data. RESULTS: We included 174 participants with a court-ordered compulsory admission. At baseline, the most common dangerousness criterion was inability to cope in society. Any type of severe or very severe dangerousness decreased from 86.2% at baseline to 36.2% at 6 months and to 28.7% at 12 months. Being homeless at baseline was the only variable which was significantly associated with persistently high levels of dangerousness. CONCLUSIONS: Dangerousness decreased in about two-thirds of the patients after court-ordered compulsory admission. It persisted, however, in a substantial minority (approximately one-third).Declaration of interestNone.

MicroRNAs as possible indicators of drug sensitivity in breast cancer cell lines.

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally. In this way they might influence whether a cell is sensitive or resistant to a certain drug. So far, only a limited number of relatively small scale studies comprising few cell lines and/or drugs have been performed. To obtain a broader view on miRNAs and their association with drug response, we investigated the expression levels of 411 miRNAs in relation to drug sensitivity in 36 breast cancer cell lines. For this purpose IC50 values of a drug screen involving 34 drugs were associated with miRNA expression data of the same breast cancer cell lines. Since molecular subtype of the breast cancer cell lines is considered a confounding factor in drug association studies, multivariate analysis taking subtype into account was performed on significant miRNA-drug associations which retained 13 associations. These associations consisted of 11 different miRNAs and eight different drugs (among which Paclitaxel, Docetaxel and Veliparib). The taxanes, Paclitaxel and Docetaxel, were the only drugs having miRNAs in common: hsa-miR-187-5p and hsa-miR-106a-3p indicative of drug resistance while Paclitaxel sensitivity alone associated with hsa-miR-556-5p. Tivantinib was associated with hsa-let-7d-5p and hsa-miR-18a-5p for sensitivity and hsa-miR-637 for resistance. Drug sensitivity was associated with hsa-let-7a-5p for Bortezomib, hsa-miR-135a-3p for JNJ-707 and hsa-miR-185-3p for Panobinostat. Drug resistance was associated with hsa-miR-182-5p for Veliparib and hsa-miR-629-5p for Tipifarnib. Pathway analysis for significant miRNAs was performed to reveal biological roles, aiding to find a potential mechanistic link for the observed associations with drug response. By doing so hsa-miR-187-5p was linked to the cell cycle G2-M checkpoint in line with this checkpoint being the target of taxanes. In conclusion, our study shows that miRNAs could potentially serve as biomarkers for intrinsic drug resistance and that pathway analyses can provide additional information in this context.

Brief communication: tamoxifen therapy for nonmalignant retroperitoneal fibrosis.

BACKGROUND: Anecdotal case reports suggest tamoxifen as a possible treatment for retroperitoneal fibrosis, but a systematic assessment of its effect is not available. OBJECTIVE: To describe the course and outcomes of patients with nonmalignant retroperitoneal fibrosis treated with tamoxifen. DESIGN: Prospective, consecutive series. SETTING: Single tertiary care referral center. PATIENTS: 19 patients with nonmalignant retroperitoneal fibrosis treated with tamoxifen from April 1998 through April 2005. INTERVENTION: Tamoxifen, 20 mg orally twice daily. MEASUREMENTS: Clinical improvement, laboratory variables, and follow-up computed tomography (CT) and gallium scan findings. RESULTS: Fifteen patients reported substantial resolution of symptoms after a median treatment duration of 2.5 weeks. Erythrocyte sedimentation rate and C-reactive protein also improved. Gallium scanning at follow-up showed incomplete disappearance of pathologic gallium-67 activity. Repeated CT scanning showed slow but steady mass regression in 14 of 15 clinical responders. Five patients failed treatment, including 1 patient who improved clinically. Disease recurred in 1 patient who responded to reintroduction of tamoxifen. One patient developed reversible hepatitis. LIMITATIONS: This small observational study did not have a control group. CONCLUSION: Tamoxifen may be a viable therapeutic option in the treatment of retroperitoneal fibrosis.

Impaired cisplatin influx in an A2780 mutant cell line: evidence for a putative, cis-configuration-specific, platinum influx transporter.

The effectiveness of platinum drugs in the treatment of cancer is hindered by intrinsic and acquired resistance. The cause of clinical resistance to platinum compounds is still unknown. In an attempt to identify new cellular mechanisms of cisplatin resistance, a one-step cisplatin-selection procedure was used to generate resistant sublines of the platinum sensitive A2780 ovarian cancer cell line. In the present study we selected an A2780 subline, A2780-Pt, that has a significantly reduced ability to accumulate cisplatin (36% of the parent A2780 cell line) and consequently shows a clear cisplatin-resistant phenotype (resistance factor, i.e., RF: 8.6). The A2780-Pt cell line was specifically cross-resistant to carboplatin (RF: 12.0), tetraplatin (RF: 8.1) and oxaliplatin (RF: 6.1) which was associated with a reduced cellular platinum accumulation (50%, 54% and 58% of A2780, respectively). No cross-resistance was found for a variety of other anticancer agents. Further experiments to determine the cause of the platinum resistance of the A2780-Pt cell line revealed that: (1) impaired cellular platinum accumulation could not be attributed to aberrant expression of MRP2 (ABCC2), CTR1 (SLC31A1), ATP7A or ATP7B, (2) resistance was not associated with platinum inactivation by metallothionein and glutathione, (3) the platinum efflux rate was similar to that of A2780, (4) the defect in cellular accumulation and the resistance could be overcome by treatment with cisplatin nanocapsules, consistent with impaired influx, and (5) the defect in accumulation is specific for platinum compounds in the cis-configuration, since A2780-Pt cells did not show reduced accumulation of transplatin. This specificity suggests that not passive diffusion but an inward transporter is impaired in A2780-Pt. In conclusion, we generated an A2780 subline that showed a uniquely stable platinum resistance phenotype, which could theoretically be caused by an impaired inward transporter specific for cis-configurated platinum compounds.

Secondary radiation damage as the main cause for unexpected volume effects: a histopathologic study of the parotid gland.

PURPOSE: To elucidate with a histopathological study the mechanism of region-dependent volume effects in the partly irradiated parotid gland of the rat. METHODS AND MATERIALS: Wistar rats were locally X-irradiated with collimators with conformal radiation portals for 100% volume and 50% cranial/caudal partial volumes. Single doses up to 40 Gy were applied. Parotid saliva samples were collected, and the three lobes of the parotid gland were examined individually on the macro- and micromorphologic level up to 1 year after irradiation. RESULTS: Dose-dependent loss of gland weight was observed 1 year after total or partial X-irradiation. Weight loss of the glands correlated very well with loss of secretory function. Irradiating the cranial 50% volume (implicating a shielded lateral lobe) resulted in substantially more damage in terms of weight loss and loss of secretory function than 50% caudal irradiation (shielding the ventral and dorsal lobe). Histologic examinations of the glands 1 year after irradiation revealed that the shielded lateral lobe was severely affected, in contrast to the shielded ventral and dorsal lobes. Time studies showed that irradiation of the cranial 50% volume caused late development of secondary damage in the shielded lateral lobe, becoming manifest between 240 and 360 days after irradiation. The possible clinical significance of this finding is discussed. CONCLUSION: It is concluded that the observed region-dependent volume effect for late function loss in the rat parotid gland after partial irradiation is mainly caused by secondary events in the shielded lateral lobe. The most probable first step (primary radiation event) in the development of this secondary damage is radiation exposure to the hilus region (located between the ventral and dorsal lobe). By injuring major excretory ducts and supply routes for blood and nerves in this area, the facility system necessary for proper functioning of the nonexposed lateral lobe is seriously affected. The unexpected volume effect in the rat might have consequences for treatment strategies in radiotherapy, implicating not only salivary glands but also other organs with a seemingly homogeneous distribution of radiosensitive elements, a situation wherein volume effects have not been anticipated up to now.

Influence of adjacent low-dose fields on tolerance to high doses of protons in rat cervical spinal cord.

PURPOSE: The dose-response relationship for a relatively short length (4 mm) of rat spinal cord has been shown to be significantly modified by adjacent low-dose fields. In an additional series of experiments, we have now established the dose-volume dependence of this effect. METHODS AND MATERIALS: Wistar rats were irradiated on the cervical spinal cord with single doses of unmodulated protons (150 MeV) to obtain sharp lateral penumbras, by use of the shoot-through technique, which employs the plateau of the depth-dose profile rather than the Bragg peak. Three types of inhomogeneous dose distributions were administered: Twenty millimeters of cervical spinal cord were irradiated with variable subthreshold (= bath) doses (4 and 18 Gy). At the center of the 20-mm segment, a short segment of 2 mm or 8 mm (= shower) was irradiated with variable single doses. These inhomogeneous dose distributions are referred to as symmetrical bath-and-shower experiments. An asymmetrical dose distribution was arranged by irradiation of 12 mm (= bath) of spinal cord with a dose of 4 Gy. The caudal 2 mm (= shower) of the 12-mm bath was additionally irradiated with variable single doses. This arrangement of inhomogeneous dose distribution is referred to as asymmetrical bath-and-shower experiment. The endpoint for estimation of the dose-response relationships was paralysis of the fore limbs or hind limbs and confirmation by histology. RESULTS: The 2-mm bath-and-shower experiments with a 4-Gy bath dose showed a large shift of the dose-response curves compared with the 2-mm single field, which give lower ED50 values of 61.2 Gy and 68.6 Gy for the symmetrical and asymmetrical arrangement, respectively, compared with an ED50 of 87.8 Gy after irradiation of a 2-mm field only. If the bath dose is increased to 18 Gy, the ED50 value is decreased further to 30.9 Gy. For an 8-mm field, addition of a 4-Gy bath dose did not modify the ED50 obtained for an 8-mm field only (23.2 and 23.1 Gy). CONCLUSIONS: The spinal cord tolerance of relatively small volumes (shower) is strongly affected by low-dose irradiation (= bath) of adjacent tissue. The results of all bath-and-shower experiments show the effect of a low bath dose to be highest for a field of 2 mm, less for 4 mm, and absent for 8 mm. Adding a 4-Gy bath to only 1 side of a 2-mm field still showed a large effect. Because glial progenitor cells are known to migrate over at least 2 to 3 mm, this observation indicates that interference with stem cell migration is not the most likely mechanism of a bath effect.