Inhibition of P-glycoprotein (ABCB1)- and multidrug resistance-associated protein 1 (ABCC1)-mediated transport by the orally administered inhibitor, CBT-1((R))

Cellular expression of ATP-binding cassette (ABC) transport proteins, such as P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP1), or ABCG2, is known to confer a drug-resistant phenotype. Thus, the development of effective transporter inhibitors could be of value to cancer treatment. CBT-1 is a bisbenzylisoquinoline plant alkyloid currently in development as a Pgp inhibitor. We characterized its interactions with the three major ABC transporters associated with drug resistance - Pgp, MRP1 and ABCG2 - and compared it to other known inhibitors. CBT-1 completely inhibited rhodamine 123 transport from Pgp-overexpressing cells at a concentration of 1muM. Additionally, 1 microM completely reversed Pgp-mediated resistance to vinblastine, paclitaxel and depsipeptide in SW620 Ad20 cells. CBT-1 was found to compete [(125)I]-IAAP labeling of Pgp with an IC(50) of 0.14 microM, and low concentrations of CBT-1 (<1 microM) stimulated Pgp-mediated ATP hydrolysis. In MRP1-overexpressing cells, 10 microM CBT-1 was found to completely inhibit MRP1-mediated calcein transport. CBT-1 at 25 microM did not have a significant effect on ABCG2-mediated pheophorbide a transport. Serum levels of CBT-1 in samples obtained from eight patients receiving CBT-1 increased intracellular rhodamine 123 levels in CD56+ cells 2.1- to 5.7-fold in an ex vivo assay. CBT-1 is able to inhibit the ABC transporters Pgp and MRP1, making it an attractive candidate for clinical trials in cancers where Pgp and/or MRP1 might be overexpressed. Further clinical studies with CBT-1 are warranted.     

Examining the service‐related experiences and outcomes of caregivers involved in a system of care who experienced everyday discrimination

Individuals who report everyday experiences of discrimination are at heightened risk for adverse health outcomes and tend to report underutilization of health services. Systems of care (SOCs) have the potential to engage members of minority groups and to reduce health disparities. We examined the service‐related experiences of predominantly Latinx caregivers enrolled in a SOC for their children with severe psychological health needs. We used independent samples t‐tests and regression analyses to compare relations among service access, perceived service characteristics, and caregiver stress according to whether caregivers reported frequent or infrequent discrimination. The frequent discrimination group scored significantly higher on dimensions of stress and had greater dosage than the infrequent group. There were no differences in relations between service characteristics and outcomes by group. Findings indicated important differences in the service‐related experiences and outcomes of caregivers who reported frequent and infrequent discrimination. We discuss limitations and implications.     

Successful immune tolerance induction by FVIII in hemophilia A patients with inhibitor may occur without deletion of FVIII‐specific T cells

Summary. Background: The development of an inhibitor is the major complication facing patients with hemophilia A treated by administration of factor (F) VIII concentrates. Restoration of tolerance to FVIII can be achieved by prolonged administration of FVIII (immune tolerance induction, ITI). Although ITI has been used for more than 30 years in patients with hemophilia A and inhibitor, its mechanism of action is still poorly understood. Objectives: As administration of high doses of antigen can induce the apoptosis of the T cells recognizing the antigen, a potential mechanism of action of ITI may be the deletion of FVIII‐specific T cells. Patients/Methods: We studied the CD4+ T‐cell response to FVIII in five (one mild, one moderate and three severe) patients successfully desensitized by administration of FVIII and in control subjects. Results: Following repeated stimulation with autologous dendritic cells loaded with FVIII, FVIII‐specific T oligoclonal cell lines were expanded from the blood of one of the successfully desensitized patients. The FVIII‐specific T cells produced IL‐5, IL‐13 and IL‐2. By contrast, FVIII‐specific T‐cell lines could not be derived from three patients with mild hemophilia A without inhibitor or from four normal control subjects. Conclusions: These data represent the first analysis of the cellular mechanisms regulating the induction of tolerance to FVIII. They demonstrate that successful tolerance induction may occur without deletion of FVIII‐specific T cells.     

Canine cranial reconstruction using autologous bone marrow stromal cells

Limited-sized transplants of culture-expanded autologous or allogeneic bone marrow stromal cells (BMSCs) form cortico-cancellous bone in rodent models. Initiation of clinical studies using autologous BMSC transplantation requires effective bone formation among sizable transplants in a large animal model as well as noninvasive techniques for evaluating transplant success. Here, we obtained bone marrow from the femurs of six dogs and expanded BMSCs in tissue culture. Autologous BMSC-hydroxyapatite/tricalcium phosphate (HA/TCP) transplants were introduced into critical-sized calvarial defects and contralateral control skull defects received HA/TCP vehicle alone. At intervals ranging from 2 to 20 months, transplants were biopsied or harvested for histological and mechanical analysis. Noninvasive studies, including quantitative computed tomography scans and ultrasound, were simultaneously obtained. In all animals, BMSC-containing transplants formed significantly more bone than their control counterparts. BMSC-associated bone possessed mechanical properties similar to the adjacent normal bone, confirmed by both ultrasound and ex vivo analysis. Evaluation by quantitative computed tomography confirmed that the extent of bone formation demonstrated by histology could be discerned through noninvasive means. These results show that autologous cultured BMSC transplantation is a feasible therapy in clinical-sized bone defects and that such transplants can be assessed noninvasively, suggesting that this technique has potential for use in patients with certain bone defects.     

The efficacy of mesenchymal stem cells to regenerate and repair dental structures

OBJECTIVES: Identification, characterization, and potential application of mesenchymal stem cells (MSC) derived from human dental tissues. METHODS: Dental pulp and periodontal ligament were obtained from normal human impacted third molars. The tissues were digested in collagenase/dispase to generate single cell suspensions. Cells were cultured in alpha-MEM supplemented with 20% fetal bovine serum, 2 mM l-glutamine, 100 microM l-ascorbate-2-phosphate. Magnetic and fluorescence activated cell sorting were employed to characterize the phenotype of freshly isolated and ex vivo expanded cell populations. The developmental potential of cultured cells was assessed following co-transplantation with hydroxyapetite/tricalcium phosphate (HA/TCP) particles into immunocompromised mice for 8 weeks. RESULTS: MSC were identified in adult human dental pulp (dental pulp stem cells, DPSC), human primary teeth (stem cells from human exfoliated deciduous teeth, SHED), and periodontal ligament (periodontal ligament stem cells, PDLSC) by their capacity to generate clongenic cell clusters in culture. Ex vivo expanded DPSC, SHED, and PDLSC populations expressed a heterogeneous assortment of makers associated with MSC, dentin, bone, smooth muscle, neural tissue, and endothelium. PDLSC were also found to express the tendon specific marker, Scleraxis. Xenogeneic transplants containing HA/TCP with either DPSC or SHED generated donor-derived dentin-pulp-like tissues with distinct odontoblast layers lining the mineralized dentin-matrix. In parallel studies, PDLSC generated cementum-like structures associated with PDL-like connective tissue when transplanted with HA/TCP into immunocompromised mice. CONCLUSION: Collectively, these data revealed the presence of distinct MSC populations associated with dental structures with the potential of stem cells to regenerate living human dental tissues in vivo.     

Text messaging as a new method for injury registration in sports: A methodological study in elite female football

Methodological differences in epidemiologic studies have led to significant discrepancies in injury incidences reported. The aim of this study was to evaluate text messaging as a new method for injury registration in elite female football players and to compare this method with routine medical staff registration. Twelve teams comprising 228 players prospectively recorded injuries and exposure through one competitive football season. Players reported individually by answering three text messages once a week. A designated member of the medical staff conducted concurrent registrations of injuries and exposure. Injuries and exposure were compared between medical staff registrations from nine teams and their 159 affiliated players. During the football season, a total of 232 time‐loss injuries were recorded. Of these, 62% were captured through individual registration only, 10% by the medical staff only, and 28% were reported through both methods. The incidence of training injuries was 3.7 per 1000 player hours when calculated from individual registration vs 2.2 from medical staff registration [rate ratio (RR): 1.7, 1.2–2.4]. For match injuries, the corresponding incidences were 18.6 vs 5.4 (RR: 3.4, 2.4–4.9), respectively. There was moderate agreement for severity classifications in injury cases reported by both methods (kappa correlation coefficient: 0.48, confidence interval: 0.30–0.66).     

Participation and retention in a study of female condom use among women at high STD risk

PURPOSE: Differential participation and retention can bias the findings of a follow-up study. This problem was evaluated in a study of barrier contraception among women at high STD risk. The goal of this study was to identify predictors of participation and retention and determine whether they could influence study results. METHODS: Six-month follow-up study of women attending STD clinics. Determinants of participation and retention were evaluated using logistic and proportional hazards models. RESULTS: Agreement to participate was associated with young age, black race, low education and income, older age at first intercourse, the number of lifetime partners, and STD history. Early attrition was associated with young age, non-black race, higher income, lack of interest/commitment to using the female condom, high coital frequency, no STD history, not using a birth control method at baseline, and with inconsistent condom use, high coital frequency, and pregnancy during follow up. CONCLUSIONS: There was little evidence that differential participation influenced the validity of the study. Differential attrition may have biased behavioral measures of intervention effectiveness, but not necessarily measures of condom use effectiveness.     

Inhibitor of histone deacetylation, depsipeptide (FR901228), in the treatment of peripheral and cutaneous T-cell lymphoma: a case report.

Depsipeptide, FR901228, has demonstrated potent in vitro and in vivo cytotoxic activity against murine and human tumor cell lines. In the laboratory, it has been shown to be a histone deacetylase (HDAC) inhibitor. In a phase I trial of depsipeptide conducted at the National Cancer Institute, 3 patients with cutaneous T-cell lymphoma had a partial response, and 1 patient with peripheral T-cell lymphoma, unspecified, had a complete response. Sézary cells isolated from patients after treatment had increased histone acetylation. These results suggest that inhibition of HDAC is a novel and potentially effective therapy for patients with T-cell lymphoma.