Quality of Life and Mental Health in Older Adults with Obesity and Frailty: Associations with a Weight Loss Intervention.

OBJECTIVE: To examine the bi-directional associations of a weight loss intervention with quality of life and mental health in obese older adults with functional limitations. DESIGN: Combined-group analyses of secondary variables from the MEASUR-UP randomized controlled trial. SETTING: Academic medical center. PARTICIPANTS: Obese community-dwelling men and women (N = 67; age ≥60; BMI ≥30) with functional limitations (Short Physical Performance Battery [SPPB] score of 4-10 out of 12). INTERVENTION: Six-month reduced calorie diet at two protein levels. MEASUREMENTS: Weight, height, body composition, physical function, medical history, and mental health and quality of life assessments (Center for Epidemiologic Studies Depression Scale [CES-D]; Profile of Mood States [POMS], Pittsburgh Sleep Quality Index [PSQI]; Perceived Stress Scale [PSS]; Satisfaction with Life Scale [SWLS]; and Short Form Health Survey [SF-36]) were acquired at 0, 3 and 6 months. RESULTS: Physical composite quality of life (SF-36) improved significantly at 3 months (ß = 6.29, t2,48 = 2.60, p = 0.012) and 6 months (ß = 10.03, t2,48 = 4.83, p < 0.001), as did several domains of physical quality of life. Baseline depression symptoms (CES-D and POMS) were found to predict lower amounts of weight loss; higher baseline sleep latency (PSQI) and anger (POMS) predicted less improvement in physical function (SPPB). CONCLUSION: The significant bi-directional associations found between a weight loss intervention and mental health/quality of life, including substantial improvements in physical quality of life with obesity treatment, indicate the importance of considering mental health and quality of life as part of any weight loss intervention for older adults.

Multidrug resistance-modifying components in human plasma with potential clinical significance.

P-Glycoprotein (P-gp) and multidrug resistance protein (MRP) are plasma membrane associated proteins which can confer multidrug resistance (MDR) to cancer cells by lowering the intracellular amount of drug. Although clinical trials with MDR-reverting agents have been initiated, not much attention has been paid to blood components which may modulate the activity of P-gp or MRP. The present investigation was performed to identify and characterize blood components which may influence the drug content and the drug cytotoxicity of MDR cells. Human plasma, from healthy volunteers, was tested for its effects on the daunorubicin (DNR) accumulation and cytotoxicity in the MDR cell lines SW-1573/2R160 (2R160) and GLC4/ADR containing P-gp and MRP, respectively. The data were compared to the effects observed in wild-type cells. MDR-modifying plasma components were isolated by extraction procedures and characterized using ultrafiltration, high-performance liquid chromatography (HPLC) and mass spectrometry. An increase in the proportion of plasma in the culture medium led to a reduction of the ratio between the DNR content of wild-type and corresponding MDR cells. At 100% plasma we observed an increase in the cellular DNR content of 2R160 cells, which was 10-30% (median 18%) of the maximum possible increase induced by well-known MDR-reverting agents, such as verapamil (for GLC4/ADR cells: 10-20%, median 15%). The DNR cytotoxicity in MDR cells also increased with an increasing amount of plasma included in the culture media. There was neither an increase in the cellular DNR content nor an effect on the DNR cytotoxicity in wild-type cells. Plasma extract analysis by HPLC showed a major peak which increased the DNR content of MDR cells. The HPLC column retention time of this fraction was identical to that of a standard of cortisol and it was further confirmed to be cortisol using mass spectrometry. Moreover, inclusion of a standard of cortisol in culture media induced a similar effect. We analyzed the data for one of the plasma pools and found that blood cortisol was responsible for the MDR-modulating effect only for 35% of the effect of 100% plasma. Other plasma components were responsible for the remaining modulation effect on MDR cells. In conclusion, the DNR pumping activity of P-gp and MRP is inhibited by human plasma, resulting in 10-30% of the maximum possible increase in cellular drug content. Based on cellular pharmacokinetic calculations this percentage will most likely increase at clinical levels of drug resistance (reaching 40-50%). In one sample blood cortisol accounted for 35% of the effect of plasma on the DNR content in MDR 2R160 cells. These data show the need for additional studies to test plasma samples for their MDR modulating effects before the administration of MDR-reverting agents in chemotherapy. The data suggest that the effectiveness of chemotherapeutic drugs may be enhanced when administered in accordance with the circadian peak of endogenous corticoids.

The P-glycoprotein-mediated relative decrease in cytosolic free drug concentration is similar for several anthracyclines with varying lipophilicity.

We have used a new methodology to measure the activity of P-glycoprotein (P-gp) in multidrug-resistant (MDR) tumor cells. This activity leads to a lower cytosolic concentration and a lower cytotoxicity of the classical anthracyclines, daunorubicin (DNR), and doxorubicin (DOX). It has been reported that the anthracycline idarubicin (IDA), which is more lipophilic, has a higher clinical efficacy in acute myeloid leukemias (AML) than DNR and DOX. In our study, the aim was to determine for a series of anthracyclines how variations in the passive drug influx rate as well as the P-gp-mediated drug pumping rate affect their cytosolic free drug concentrations and how these parameters are related to drug cytotoxicity. We selected six anthracyclines: DOX, DNR, epidoxorubicin (EPI), IDA, cyano-morpholino-doxorubicin (CMD), and carminomycin (CAR), ordered according to their increasing octanol/PBS buffer concentration ratios, respectively. To measure the passive permeation coefficient, the P-gp-mediated drug pumping rate, and the cytosolic free drug concentration, we used a flow-through system in which cells were exposed to a flowing medium containing drugs. We used the MDR P-gp-containing cell line KB8-5. It was shown that the passive drug permeation coefficient as well as the drug pumping rate of P-gp increased with increasing lipophilicity in this series of anthracyclines. The cytosolic free drug concentration was lowered by P-gp to a similar extent in KB8-5 cells for all drugs tested (40-50% of the extracellular drug concentration). CMD, IDA, and CAR had lower IC50 values and lower resistance factors in comparison to DOX, DNR, and EPI. Verapamil reversed the resistance for all anthracyclines tested. In conclusion, for several anthracyclines the activity of P-gp leads to a similar relative decrease in the cytosolic free drug concentration; consequently, the reported lower resistance factor of IDA compared to that of DNR is not due to the inability of P-gp to export IDA from cells.

Daunorubicin efflux against a concentration gradient in non-P-glycoprotein multidrug-resistant lung-cancer cells.

Multidrug-resistant, human non-small-cell lung carcinoma SW-1573/2R120 (2R120) cells, not containing the drug efflux pump P-glycoprotein (Pgp), have reduced initial daunorubicin (DN) accumulation rates and decreased cellular steady-state drug concentrations. Previously we found indications of the presence of a plasma membrane "vacuum cleaner", pumping DN directly from the membrane, and reported evidence of active DN pumping using digitonin. Further evidence of active DN pumping is now provided via a different methodology and the active drug pump flux is estimated. Cells were exposed to a flowing medium containing the cytotoxic agent DN. After reaching a steady state, in which net DN uptake equals net DN efflux, high concentration pulses of vincristine (VCR) were injected into the flowing medium. A rapid increase in cellular DN content was observed, while only a minimal effect was seen in SW-1573 wild-type cells. After passage of the VCR pulse, the extra accumulated DN was effluxed against a concentration gradient. Upon increasing the VCR concentration, a maximum pump inhibition was reached which was similar to the effect of cellular energy depletion. Similar effects were observed for Pgp-containing SW-1573/2R160 (2R160) cells as well as non-Pgp MDR human small-cell lung carcinoma GLC4/ADR cells. With increasing extracellular DN concentrations, saturation of the VCR-induced DN influx was observed (DN medium concentration 2.5 microM at 1/2 Vmax). At an extracellular DN concentration of 5 microM, higher concentrations of VCR were needed to reach the maximum effect in 2R120 cells than at 0.5 microM DN. This is an indication of competitive interaction between DN and VCR for the putative DN efflux system. In summary, we found indications of inhibition of active DN efflux by VCR and DN efflux against a concentration gradient in non-Pgp MDR 2R120 and GLC4/ADR cells. These features are consistent with the presence of a multidrug transporter, different from Pgp, in the plasma membrane of these cells.

The human multidrug resistance-associated protein MRP is a plasma membrane drug-efflux pump.

The multidrug-resistance associated protein MRP is a 180- to 195-kDa membrane protein associated with resistance of human tumor cells to cytotoxic drugs. We have investigated how MRP confers drug resistance in SW-1573 human lung carcinoma cells by generating a subline stably transfected with an expression vector containing MRP cDNA. MRP-overexpressing SW-1573 cells are resistant to doxorubicin, daunorubicin, vincristine, VP-16, colchicine, and rhodamine 123, but not to 4'-(9-acridinylamino)methanesulfon-m-anisidide or taxol. The intracellular accumulation of drug (daunorubicin, vincristine, and VP-16) is decreased and the efflux of drug (daunorubicin) is increased in the transfectant. The decreased accumulation of daunorubicin is abolished by permeabilization of the plasma membrane with digitonin, showing that MRP can lower the intracellular daunorubicin level against a concentration gradient. Anti-MRP antisera predominantly stain the plasma membrane of MRP-overexpressing cells. We conclude that MRP is a plasma membrane drug-efflux pump.

A plasma membrane 'vacuum cleaner' for daunorubicin in non-P-glycoprotein multidrug-resistant SW-1573 human non-small cell lung carcinoma cells. A study using fluorescence resonance energy transfer.

A multidrug resistant (MDR) human non-small cell lung carcinoma cell line, SW-1573/2R120 (2R120), not containing the drug-efflux pump P-glycoprotein (PgP), has been studied for the transport of daunorubicin (DN) across the cellular plasma membrane. Earlier, reduced initial DN-uptake rates and lower cellular DN steady-state concentrations were found for this cell line, when it was compared to the SW-1573 wild-type cell line. This finding was an indication for the presence of another cellular drug-efflux pump. However, we found similar DN-efflux rates in drug-free medium for the two cell lines, while for Pgp-containing MDR SW-1573/2R160 (2R160) cells the efflux rate was increased compared to wild-type cells. In order to elucidate differences in DN transport across the cellular plasma membrane, the association of DN with plasma membranes of intact cells was investigated, using fluorescence-resonance-energy transfer. For this purpose, the plasma-membrane probe 1-(4-trimethyl-ammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) was chosen since, because of the overlap between the emission spectrum of TMA-DPH and the excitation spectrum of DN, transfer of energy can be achieved from TMA-DPH to DN. Cells were loaded with TMA-DPH and, after addition of 10 microM DN, the TMA-DPH fluorescence was quenched. Rapid initial quenching proved to be similar in the MDR 2R160 (Pgp-containing) cells and in the SW-1573 wild-type cells (21 +/- 1% and 20 +/- 2%, respectively), but was less in the MDR 2R120 cells not containing Pgp (14 +/- 1%). This finding correlated with a lowered amount of DN dissolved in the plasma membrane of 2R120 cells. We interpret these data to be the result of a 'vacuum-cleaner' pumping system other than Pgp which removes DN from a plasma membrane compartment and equilibrates relatively slowly with the interior of the cell.

Cellular daunomycin fluorescence in multidrug resistant 2780AD cells and its relation to cellular drug localisation.

Multidrug resistant (MDR) 2780AD human ovarian carcinoma cells were loaded with the fluorescent anticancer agent daunomycin (DN). Fluorescence anisotropy was lower than for corresponding A2780 wild-type cells, indicating that DN was less rigidly bound than in the wild-type cells. Average fluorescence quenching of DN was lower for 2780AD cells. Data were fitted into a model with a highly quenched fraction (fraction A), corresponding to DN intercalated in DNA, and an unquenched fraction (fraction B). The ratio A/B was one order of magnitude lower for the MDR cells than for the wild-type cells. Two other MDR cell lines were investigated and low A/B ratios were found in both cases. Thus, evidence has been provided that in MDR cells the DNA-bound fraction is relatively low and that more free DN is present, for example in acidic vesicles.