Reduction In Homing Research Articles

The consequences of COVID-19 lockdown for formal and informal resource utilization among home-dwelling people with dementia: results from the prospective PAN.DEM study

BackgroundCOVID-19 isolated home-dwelling people with dementia (PwD) from home care services, respite care, and daytime activities. We aimed to investigate the consequences of these restrictions on informal (family, friends) and formal (homecare staff) resource utilization among co-residing (e.g., spouses) and visiting caregivers (e.g., children).Methods105 PwD (≥65 years old) and their caregivers were included in the prospective PANdemic in DEMentia (PAN.DEM) study, which was initiated when the ongoing stepped-wedge, cluster randomized LIVE@Home.Path trial (N = 438) was temporarily halted due to the pandemic. Primary outcome was change in resource utilization assessed by the Resource Utilization in Dementia Care (RUD) instrument in pre- (12 Dec. 2019 to 11 Mar. 2020) and during the lockdown periods (20 April 2020 to 15 May 2020). Degree of cognitive impairment was assessed by Mini-Mental Status Examination (MMSE), and physical functioning and independent living skills by Physical Self-Maintenance Scale and Lawton Instrumental Activities of Daily Living Scale. Associations between informal and formal care utilization, socio-demographics, and clinical variables were assessed by descriptive statistics and Ordinary Least Squares models (OLS).ResultsMean age for PwD was 81.8 years; 61% were female; 45.6% lived alone, and the mean MMSE score was 20.8 (SD ± 3.7). PwD with co-residents (44%) were younger (78.4 years) than those who were living alone (84.5 years; P < 0.001). During the first 2 months of lockdown, PwD missed on average 20.5 h of formal care in a month (P < 0.001) leading to an approximately 100% increase in informal care, which was particularly pronounced in personal hygiene (6.9 vs. 11.4 days in a month, P < 0.001) and supervision (9.2 vs. 17.6 days in a month; P < 0.001). Visiting caregivers increased by 1.9 days (SD ± 11.5), but co-residing caregivers increased their number of days providing ADL by approximately 7 days per month (β = 6.9; CI, 0.39–13.1, P < 0.05) after adjusting for PwD and caregiver demographics and clinical variables. Decrease in home nursing care was particularly visible for PwD living alone (− 6.1 vs. -1.3 h per month, P = 0.005). Higher cognitive function (β = − 0.64, CI, − 1.26 – 0.02, P = 0.044) was associated with reduction in home nursing service during the lockdown.ConclusionThe care situation for PwD changed dramatically in the early phase of the COVID-19 pandemic, especially for those living alone who received less support from homecare services and visiting caregivers. For future crises and the forthcoming post-pandemic period, health authorities must plan better and identify and prioritize those in greatest need.Trial registrationClinicalTrials.gov; NCT04043364.

Improved Sleep Quality Improves Blood Pressure Control among Patients with Chronic Kidney Disease: A Pilot Study

Background: Despite the abundance of data documenting the consequences of poor sleep quality on blood pressure (BP), no previous study to our knowledge has addressed the impact of sleep improvement on resistant hypertension among patients with chronic kidney disease (CKD). Methods: The aim of this pilot study was to determine whether improved sleep quality and duration will improve BP control in patients with resistant hypertension and CKD. It was a prospective single-center cohort study that involved 30 hypertensive subjects with CKD presenting with primary resistant hypertension and poor sleep quality or duration <6 h/night. Sleep quality and duration were modified using either sleep hygiene education alone or adding sleep medication. The cohort’s BP was followed every 3 months for 6-month duration. The average home and clinic BPs were collected at each follow-up visit. The primary outcome baseline change in systolic BP (SBP) and diastolic BP (DBP; home and clinic) at 3 and 6 months after documented sleep improvement. Secondary outcomes included change from baseline in mean arterial pressure, and delta SBP after sleep improvement. Results: African American patients represented 50% of the cohort. All patients had evidence of CKD with GFR ≤60 mL/min and were obese with 40% having type 2 diabetes mellitus. The primary endpoint of change in clinic SBP and DBP was significantly reduced at 3 months, baseline 156 ± 15/88 ± 8 vs. 3 months 125 ± 14/73 ± 7 (p < 0.0001). This difference persisted at 6 months. However, there was no further reduction in-home or clinic BPs between the 3- and 6-month periods. Home and clinic average delta SBP change at 3 months from baseline was –34.4 ± 15 and –30.8 ± 19 mm Hg respectively. Delta SBP change was associated with sleep improvement of >6 h/night, that is, gaining an extra 3–4 h’ sleep duration, home; R² = 0.66, p < 0.0001 and clinic; R² = 0.49, p < 0.0001. Conclusion: Optimizing sleep quality and duration to >6 h/night improved BP control and was associated with a significant delta change in SBP within 3 months of follow-up. Physicians should obtain a sleep history in patients with CKD who present with resistant hypertension.

CRISPR-Cas9 Mediated CD45 Knockout Inactivates Src Family Kinases and Impairs Cell Migration in Multiple Myeloma

IntroductionMultiple myeloma (MM) is a plasma cell malignancy that manifests continuous cell dissemination to multiple bone marrow (BM) niches and extramedullary (EM) sites. However, the molecular mechanisms behind this phenomenon remain elusive. CD45, a receptor tyrosine phosphatase, is an important regulator for T-cell and B-cell signaling pathways. In MM, the loss of CD45 expression has been correlated with earlier disease progression and inferior treatment outcomes. The downstream targets of CD45, Src family kinases (SFK), are associated with cell migration in many malignancies. It is also known to interact with proline-rich kinase (Pyk2) that binds to cytoskeleton-regulating proteins. Our previous in vitro studies demonstrated a ‘metastatic’ phenotype for CD45 negative MM. We hypothesise that CD45 acts as a marker for disease progression and mediates cell mobility through SFKs.MethodCD45 expression in human myeloma cell lines (HMCL) was assessed by flow cytometry. To investigate the functions of CD45 in MM, CRISPR-Cas9 mediated CD45 knockout (CD45KO) models were established from a HMCL, OCI-MY1. The resulting phenotypic and transcriptional changes were identified by immunoblotting, modified Boyden chamber assays, RNA sequencing and Phospho Explorer Antibody Array. SFK inhibitor (Saracatinib), Pyk2 inhibitor (PF573228) and siRNAs were used to validate the role of SFK (predominately Lyn and Fyn) and Pyk2 in migration.ResultsWe first compared 2 pairs of HMCL contemporaneously derived from BM and extramedullary disease (EM) in the same patient: TK1 (BM) and TK2 (EM), and TK17 (EM) and TK18 (BM). Both TK1 and TK18 had higher CD45 expression than their paired HMCL as expected.To avoid confounding intercellular genetic heterogeneity, we generated CD45KO models from OCI-MY1 and the loss of extracellular and intracellular portion of CD45 was confirmed by flow cytometry and immunoblotting. OCI-MY1 CD45KO cells showed significant SFK (Lyn and Fyn) and Pyk2 inactivation as compared to CD45 wild-type (CD45WT) cells. These cells demonstrated a significant reduction in homing capacity towards healthy and MM-patient derived BM stromal cells (reduced to 11.5% and 2.7%, p<0.0001, respectively) compared with the CD45WT cells. Treatment of CD45WT cells with Saracatinib and PF573228 similarly inhibited the homing capacity (47.3%, p<0.0001 and 71.3%, p<0.01 respectively). Moreover, silencing of Lyn and Fyn with siRNAs in CD45WT cells recapitulated the findings seen with the CD45KO cells (76%, p<0.01 and 55%, p<0.001, reduction in homing, respectively).The inactivation of SFK prompted us to investigate the transcriptional changes in the CD45KO cells. RNA sequencing identified differentially expressed migration-related genes in the CD45KO cell, in particular ADAM19, PARVB, AFAP1L2 and ITGAL, thus raising the possibility that dysregulation of these genes led to the observed reduction of homing potential of the CD45KO cells. To further understand the role of CD45 phosphatase activity, we analysed protein phosphorylation profiles in the CD45KO and CD45WT cells. In addition to the recognised inactivation of SFK and Pyk2, the Phospho Explorer Antibody Array also demonstrated reduced phosphorylation of JAK1 (Y1022), TYK2 (Y1054), c-Raf (S259) and MDM2 (S166), and increased phosphorylation of IRS-1 (S794), SHP-2 (Y580), c-Jun (Y170) and STAT6 (T645). We are currently investigating the correlation of these phosphorylation and MM homing mechanisms.ConclusionOur data demonstrate that CD45 plays an important role in regulating MM homing towards BM stroma by modulating SFK and Pyk2 activity with the loss of CD45 expression also resulting in the dysregulation of migration-related genes and widespread phosphorylation changes. Further in vivo studies evaluating the ‘metastatic’ impact of loss of CD45 expression are in progress. DisclosuresNo relevant conflicts of interest to declare.

Telerehabilitation for older people using off-the-shelf applications: acceptability and feasibility

We investigated the feasibility of providing telerehabilitation in the home as an alternative to conventional ambulatory rehabilitation. Two groups of patients were accepted for telerehabilitation. The first group were community patients who needed rehabilitation, e.g. following a stroke, a fracture or prolonged hospital admission. The second group was from two rural nursing homes where residents were identified with a recent injury, fall or hospitalisation. Telerehabilitation employed a coaching model, with fewer therapist home visits, more feedback and “homework” for the patient. Patients had a tablet computer loaded with a videoconferencing app to connect with therapists and relevant therapeutic apps. Multidisciplinary care was provided for up to 8 weeks. The majority (86%) of eligible patients consented to receive telerehabilitation in their own home (n = 61) or in the country nursing home where they lived (n = 17). Most services were delivered using the 3G and 4G wireless networks with few technical problems. On average participants felt that they had achieved 75% of the goals set at the beginning of the programme. High levels of satisfaction were recorded. There was a 50% reduction in home visits by staff, or 10 visits per patient. Speech therapists were able to double occasions of service and direct patient contact time, whilst halving their travel time. Previous experience with technology and age were not barriers to this method of delivery but did affect recruitment. Telerehabilitation using off-the-shelf technology is feasible for post-acute treatment.

A pilot outreach physiotherapy and dietetic quality improvement initiative reduces IV antibiotic requirements in children with moderate–severe cystic fibrosis

At our hospital the current model of care for children with moderate-severe CF is focused on intensive inpatient intervention, regular outpatient clinic review and specialist outreach care as required. An alternative model providing more regular physiotherapy and dietetic outreach support, in addition to these specialist services, may be more effective. 16 children (4 male; 12 female; mean age 10.9±2.93; range 4-15 years) who required >40days of IV antibiotics in the 12-months pre-intervention were enrolled. Physiotherapy included weekly-supervised exercise sessions, alongside regular review of home physiotherapy regimens. Dietetic management included 1-2 monthly monitoring of growth, appetite, intake and absorption, and nutrition education sessions. There was a 23% reduction in inpatient IV antibiotic requirement and 20% reduction in home IV antibiotic requirement during the intervention year. Cost-benefit analyses showed savings of £113,570. VO(2Peak) increased by 4.9 ml·kg·min(-1) (95%CI 1.01 to 8.71; p=0.02), and 10 m-MSWT distance and increment achieved increased by 229 m (95%CI 109 to 350; p<0.001) and 2 levels (95%CI 1 to 3; p<0.002) respectively. No significant differences in physiological and patient reported outcomes were demonstrated, although there was a possible trend towards improvement in outcomes when compared to the pre-intervention year. This pilot programme demonstrated a reduction in IV and admission requirements with a cost benefit in a small group of children with moderate-severe CF. A fully powered clinical trial is now warranted.

Leukemia-Induced Alterations in Bone Marrow Cytokine and Chemokine Levels Contribute to Altered Stem Cell Lodgment and Impairment of Normal Stem Cell Growth in CML

Abstract 962Specialized bone marrow (BM) microenvironmental niches are essential for hematopoietic stem cell (HSC) lodgment and maintenance. However microenvironmental interactions of leukemia stem cells (LSC) are poorly understood. Although chronic myelogenous leukemia (CML) results from HSC transformation by the BCR-ABL gene, the role of the microenvironment in modulating leukemia development is not known. We employed the SCL-tTA-BCR/ABL mouse model of CML to investigate the LSC interactions with the BM microenvironment. In this model, targeted expression of the BCR-ABL gene in murine HSC via a tet-regulated SCL promoter results in development of a chronic phase CML-like disorder. We have reported that LSC capacity is restricted to BCR-ABL+ cells with long-term hematopoietic stem cell (LTHSC) phenotype(LSK Flt3-CD150+CD48-) (Blood 2010 116:1212A). LSC numbers are reduced in the BM but increased in the spleen of CML mice compared with LTHSC from control mice, suggesting that LSC have altered niche interactions. LSC also demonstrate altered trafficking with significant reduction in homing of IV injected LSC to BM, and markedly increased egress of intrafemorally injected LSC to the spleen, potentially related to reduced CXCL12 levels in the BM of CML mice. In addition, levels of several chemokines and cytokines, including MIP1α, MIP1β, MIP2, IL-1α, IL-1β, TNF-α, G-CSF and IL-6, were increased in CML BM, related to increased production by malignant hematopoietic cells. We investigated whether altered chemokine and cytokine expression was associated with altered capacity of the CML BM microenvironment to support LTHSC engraftment. LTHSC from control mice or LSC from CML mice were transplanted into irradiated CML or control recipients. There was reduced engraftment of both control LTHSC and CML LSC in the BM of CML compared to control recipients at 2 weeks after transplantation, associated with reduced homing to CML BM, potentially related to low BM CXCL12 levels. The numbers of control LTHSC in the BM of CML recipient mice remained low at 4 weeks post-transplantation, whereas the numbers of CML LSC increased to numbers similar to those seen in the BM of control recipients. Culture with CML BM supernatants (SN) resulted in impaired growth of control LTHSC compared to control BM SN. In contrast the growth of CML LSC was similar following culture with CML and control BM SN. Culture with individual factors at concentrations similar to those observed in CML BM (16ng/ml MIP1α, 8ng/ml MIP1β, 2.5ng/ml IL-1α, 3.5ng/ml IL-1β, 0.05ng/ml TNF-α) resulted in significantly reduced growth of normal LTHSC compared with CML LSC. These results indicate that diffusible factors produced by leukemic cells in the CML BM environment selectively inhibit normal LTHSC compared to CML LSC growth. Exposure of a murine stromal cell line to CML BM SN resulted in reduced CXCL12 mRNA levels compared to BM SN from control mice. The cytokine G-CSF, which was increased in CML BM SN, has been reported to reduce CXCL12 transcription. We observed significant reduction of CXCL12 mRNA levels in stromal cells cultured with G-CSF (0.2ng/ml), supporting a potential role for increased G-CSF production by leukemia cells in reduced CXCL12 production by CML BM stromal cells and reduced LSC retention in the BM. We evaluated whether defects in microenvironmental function in CML were affected by imatinib treatment. Treatment of CML mice with imatinib (200mg/kg/day, 2 weeks) led to reduction in MIP1α, MIP1β, IL-1β, and IL-6 levels in BM cells. Engraftment of normal LTHSC was significantly enhanced in BM of CML recipients pre-treated with imatinib. Results obtained with the mouse model were validated using specimens obtained from CML patients. CXCL12 mRNA levels were significantly reduced in human CML compared to normal MNCs, whereas expression of MIP1α, MIP-2, IL-1α and IL-1β were increased in CML MNCs, consistent with results obtained with the mouse model. Coculture with CML MNC conditioned medium (CM) resulted in selective impairment of growth of normal CD34+CD38- primitive progenitors compared to CM from normal MNC, but did not inhibit growth of CML progenitors. We conclude that leukemia-induced alterations in BM cytokine and chemokine levels contribute to altered LSC lodgment and to selective impairment of growth of normal LTHSC in the CML BM microenvironment, leading to a relative growth advantage for CML LSC over normal LTHSC and expansion of the leukemic clone. Disclosures:Holyoake:Novartis: Research Funding; Bristol Myers Squibb: Research Funding.

Abstract 2402: Prostate cancer cell homing to bone invivo is modulated by zoledronic acid

Abstract Cancer metastasis to the skeleton is the cause of significant mortality in prostate cancer. Intervention to prevent metastasis would be the most significant advance for the majority of patients. Despite its prevalence, the mechanisms involved in the development of bone metastases remain unclear. A metastatic initiating cell (MIC) phenotype CD44+/CD24− has been identified in prostate cancer. A complementary approach to aid MIC cell recognition, involves identification of aldehyde dehydrogenase (ALDH) activity. Zoledronic acid (zol), a bone anti-resorptive agent, is currently the only bisphosphonate with proven benefit in prostate cancer. The aim of this work is to use a novel in vivo model to investigate whether zol modulates the homing of metastasis initiating cells in the early stages of prostate cancer metastasis to bone. Metatarsals from newborn mice (1-3 day old) are engrafted into a Dorsal Skinfold Chamber (DSC) implanted on a SCID mouse (5-6 weeks old) followed by intra-cardiac (i.c) injection of fluorescently labelled tumour cells (1 × 105). Prostate (PC3-GFP) tumour cells have previously been shown to home to the metatarsal within the DSC, whereas oral cancer cells (SCC4-GFP; negative control) do not home to the bone within the DSC but to lymph nodes. ZOL treatment: Animals were subdivided into groups and treated either before or after i.c. PC3-GFP tumour cell injection with i) weekly s.c injection of zol for 4 weeks (25µg/kg/inection=100μg/kg in total) or PBS or ii) a single s.c injection of zol (100μg/kg) or PBS. ALDH activity: PC3-RFP cells were sorted into ALDHhi (7%) and ALDHlow (20%) subpopulations using the ALDEFLUORkit and flow cytometry then injected into separate groups of animals and treated with zol prior to tumour cell injection. Recordings of the DSC were made at 48 hr intervals for up to 4 weeks. At the end of the study, tissue was harvested and processed for microCT, multi-photon analysis, histology and immunohistochemistry. Zol treatment significantly (p&amp;lt;0.005) reduced the adhesion of PC3-GFP cells to bone when compared to control animals. Day 15: Control 15.9±1.4 cells; weekly treatment before PC3-GFP cells, 2.1±0.3* cells; weekly treatment after, 4.4±0.7*cells; single treatment before cells, 13.6±0.8 cells; single treatment after, 14.2±1.8 cells (*p&amp;lt;0.005). ALDHhigh cells home to bone in significantly higher numbers than ALDHlow cells (Day 15: ALDHhi 12.3±1.8 cells vs. ALDHlow 1.9±0.5 cells). Treatment with weekly zol (before cell injection) reduced the number of PC3 cells homing to the bone but this was not significant (ALDHhi 12.3±1.8 cells vs. ALDHhi plus zol; 9.7±2.1 cells). Treatment with zol reduces prostate tumour cell homing to bone, with weekly treatment prior to cell administration demonstrating the greatest reduction in homing. ALDHhi cell (likely metastatic phenotype) homing appears resistant to treatment with zol in this model. Funded by Sixth European Framework Programme (PROMET). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2402. doi:10.1158/1538-7445.AM2011-2402

Altered Niche Interactions of Leukemia Stem Cells In a Chronic Phase Chronic Myelogenous Leukemia (CML) Transgenic Mouse Model.

AbstractAbstract 1212Specialized microenvironmental niches are essential for hematopoietic stem cell (HSC) lodgment and maintenance. However the niche interactions of leukemia stem cells (LSC) are largely unknown. Targeted expression of the BCR-ABL gene in murine hematopoietic stem and progenitor cells (HSPC), via a Tet-regulated SCL promoter, results in development of a chronic phase CML-like disorder (Blood 105:.324, 2005). We have employed this SCL-tTA-BCR/ABL mouse model to investigate the characteristics of LSC in CML. BCR-ABL transgenic mice were crossed with GFP transgenic mice to facilitate tracking of transplanted cells. We have reported that LSC capacity is restricted to a population of cells with LT-HSC phenotype (LSK Flt3-CD150+CD48-). BCR-ABL expression is associated with reduced numbers of LT-HSC in the BM and greatly increased numbers of LT-HSC in the spleen compared with controls(Blood 2009, 114: 858). These observations suggest that CML LT-HSC demonstrate altered niche requirements compared to normal LT-HSC. We therefore conducted additional studies to investigate whether abnormal localization of CML LT-HSC was related to reduced homing and/or reduced retention in the BM microenvironment. To evaluate LT-HSC homing, BCR-ABL+ and control LT-HSC (10,000 cells/mouse) were labeled with CFSE and injected by tail vein injection into wild type mice irradiated at 900cGy and CFSE+ cells in the BM and spleen of recipient mice were evaluated 4h after injection. We observed 32% reduction in homing of BCR-ABL+ LT-HSC to the BM of recipient mice compared to control LT-HSC (p=0.04), with similar homing to the spleen. To study trafficking from BM to extramedullary sites, BCR-ABL+ and control LT-HSC were injected directly into the right femur of irradiated congenic mice (1000 cells/mouse). Recipient mice were euthanized 2 and 4 weeks after injection and localization of LT-HSC, progenitors and WBC in the right femur, the contralateral (left) femur, and spleen analyzed by flow cytometry. We observed 4.9-fold increased numbers of BCR-ABL+ LT-HSC compared with control LT-HSC in the spleen(p=0.008) and 60% decreased numbers of BCR-ABL+ LT-HSC in the marrow compared with control LT-HSC at 4 weeks post-injection(p=0.048). Increased egress from BM to spleen was not related to BM hypercellularity. These results are consistent with enhanced egress of BCR-ABL+ LT-HSC from the BM to the spleen and/or enhanced growth in the spleen. No significant differences in expression of α4, α5, and α6 integrin and CD44 expression were seen in LT-HSC from the spleen and BM of BCR-ABL+ and control mice. A small population of β7 integrin expressing LT-HSC was seen in BM from BCR-ABL+ mice. Adhesion of LT-HSC from the spleen and BM of BCR-ABL+ and control mice to fibronectin coated wells was evaluated. LT-HSC from BM of BCR-ABL+ mice showed reduced adhesion to fibronectin after 2 hours(43±3%) compared to LT-HSC from control mice (57±3%, p=0.004), indicating impaired α4β1 and α5β1 integrin receptor function despite normal levels of receptor expression. BCR/ABL+ LT-HSC cells demonstrated higher CXCR4 expression and enhanced migration to CXCL12 (SDF-1) in a 3-hour transwell migration assay(20±5%), compared to control LT-HSC (9±3%, p=0.04). CXCL12-induced migration of BCR/ABL+ LT-HSC was completely blocked by the CXCR4 antagonist AMD3100. ELISA analysis of CXCL12 levels revealed 2.5-fold reduction in BM supernatants and 1.4-fold increase in splenic supernatants from BCR/ABL+ mice compared to control mice. We conclude that BCR-ABL expression results in significant reduction in LT-HSC homing to BM niches and markedly increased egress of LT-HSC from BM to the spleen through a combination of both intrinsic defects in LT-HSC adhesion and migration and leukemia-associated alterations in the BM and splenic microenvironments. Our results indicate LT-HSC-niche interactions are markedly perturbed in CML, potentially contributing to deregulated stem cell growth. Disclosures:No relevant conflicts of interest to declare.

Cost-Effectiveness of Rivaroxaban as VTE Prophylaxis after Total Hip Replacement in Canada.

Introduction: Rivaroxaban is a novel, oral, direct Factor Xa inhibitor under regulatory review for prevention of venous thromboembolism (VTE) after total hip and knee replacement surgery. The efficacy and safety of rivaroxaban for VTE prevention following total hip replacement (THR) was assessed in two, large, randomized, controlled trials. RECORD1 compared rivaroxaban (10 mg once daily) with subcutaneous (sc) enoxaparin (40 mg once daily) over 35 days. The primary outcome (deep vein thrombosis, non-fatal pulmonary embolism, and all-cause mortality) occurred in 1.1% of rivaroxaban patients and in 3.7% of enoxaparin patients (RRR 70%; p<0.001). Symptomatic VTE occurred in 0.3% and 0.5%, respectively. RECORD2 compared 35 days' rivaroxaban (10 mg once daily) with 10–14 days' enoxaparin (40 mg once daily) followed by placebo. The primary outcome occurred in 2.0% of the rivaroxaban group and 9.3% of the enoxaparin + placebo group (RRR 79%; p<0.001). Symptomatic VTE occurred in 0.2% and 1.2%, respectively. There were no statistical differences in major bleeding between the rivaroxaban and enoxaparin regimens in either trial. This analysis assessed the cost-effectiveness of 35 days oral rivaroxaban versus each regimen of subcutaneous enoxaparin for prevention of VTE following THR in Canada.Methods: An economic model was developed to assess the cost-effectiveness of rivaroxaban versus both durations of enoxaparin after THR in Canada. The analyses were conducted from the perspective of the Ontario (Canadian) Ministry of Health. The incidence of clinical events and their consequences on resource use and quality of life (QoL) were modeled for rivaroxaban and enoxaparin over five years. The incidence of VTE during the period of prophylaxis was based upon RECORD1 and RECORD2, and the incidence of VTE up to 90 days following surgery was extrapolated based on epidemiological data (Quinlan et al., 2007). The incidence of recurrent VTE and post-thrombotic syndrome (PTS) beyond this period was based on clinical data (Prandoni et al., 1997). To calculate resource use we assumed that 19% of patients receiving enoxaparin prophylaxis and those eventually treated for VTE on an outpatient basis would require daily home nursing visits to administer the injections (Harrison et al., 1998). This is likely to be an underestimate in light of other studies and clinical experience of VTE practice in Canada. The costs associated with clinical events (major bleed, VTE and PTS) and home visits was derived from published Canadian sources and expressed in Canadian dollars (C$). Rivaroxaban and enoxaparin costs were included. Utility values, used to demonstrate the impact of clinical events on QoL, were also derived from published literature (Haentjens et al., 2004; Rasanen et al., 2007).Results: When rivaroxaban and enoxaparin were both administered for 35 days, rivaroxaban was associated with improved clinical outcomes and an average cost saving of C$282.58 per patient. Savings were driven mainly by reduced outpatient administration. Sensitivity analyses showed that rivaroxaban remained more effective and less expensive than enoxaparin in more than 98% of the simulations. When 35 days' rivaroxaban were compared with 10–14 days enoxaparin, rivaroxaban cost an extra C$90.34 per patient. However, when the improved efficacy with rivaroxaban compared with the 10–14 day enoxaparin regimen was adjusted for QoL, rivaroxaban produced a gain in quality adjusted life years (QALYs) of 0.0027. This translates to an incremental cost per QALY of C$33,323, which is below the commonly-referenced threshold of C$50,000/QALY. Another frequently used VTE prophylaxis in Canada is Fragmin. As Fragmin has a similar efficacy and safety profile to enoxaparin, and has a higher price than enoxaparin in Canada, rivaroxaban is even more cost-effective versus Fragmin.Conclusions: Rivaroxaban is cost-effective versus 10–14 days' and 35 days' enoxaparin for the prevention of VTE following THR in Canada. This is driven by improved efficacy, with respect to clinical event costs and QoL, and the reduction in home nurse visits with use of oral rivaroxaban.

Abstract 1130: Role Of PI3Kγ For Integrin-dependent Adhesive And Migratory Functions Of Progenitor Cells In Vitro And In Vivo

Endothelial progenitor cells (EPC) are recruited to ischemic regions to improve neovascularization. β1- and β2-integrins play a crucial role for progenitor cell homing to ischemic tissues. Chemokines and their respective G-protein coupled receptors (GPCRs) are involved in the EPC homing to ischemic tissues. The phosphatidylinositol-3-kinase catalytic subunit gamma (PI3Kγ) is the PI3K isoform, which selectively transduces signals from GPCRs. Here, we investigated the role of PI3Kγ for integrin-dependent homing functions of progenitor cells. As assessed by western blot, EPC express the catalytic subunit PI3Kγ. We then studied the role of PI3Kγ for EPC migration. AS-605240 (100 nM), a selective PI3Kγ-inhibitor (Camps M, Nat. Med., 2005), significantly reduced the SDF1- and the IL-8-induced migration and the SDF1-induced transendothelial migration of human EPC. Adhesion is a further essential step during EPC homing to ischemic tissues. In this regard, the PI3Kγ-inhibitor significantly reduced the SDF1-induced adhesion of EPC on HUVEC monolayers by 69 ± 8 % and on ICAM-1, a β2-integrin ligand. However, the PI3Kγ-inhibitor did not affect the SDF1-induced adhesion of EPC on fibronectin, a β1-integrin ligand, suggesting that PI3Kγ in EPC is involved in the regulation of β2-, but not of β 1-integrin-dependent adhesion. In line with these results, inhibition PI3Kγ blocked the SDF1-induced increase of β2-, but not of β1-integrin-affinity in EPC. Beside EPC, the SDF1-induced migration and adhesion on ICAM-1 of murine bone marrow (BM)-derived Lin − progenitor cells from PI3Kγ-deficient mice (PI3Kγ − / − ) were reduced in comparison to wild type (WT) cells. In addition, PI3Kγ-deficiency led to a significant reduction of homing of murine BM-Lin − progenitor cells to ischemic muscles after intravenous infusion in the model of hind limb ischemia in comparison to WT cells (48 ± 8 % inhibition). In conclusion, these data demonstrate that PI3Kγ plays an essential role for the integrin-dependent homing of progenitor cells in vitro and in vivo. The understanding of the molecular mechanisms of progenitor cell homing is essential for the development of new therapeutic strategies in order to improve the efficacy of cell-based therapies in patients with ischemic disorders.

Human Exposure to Mosquito-Control Pesticides—Mississippi, North Carolina, and Virginia, 2002 and 2003

Public health officials weigh the risk for mosquito-borne diseases against the risk for human exposure to pesticides sprayed to control mosquitoes. Response to outbreaks of mosquito-borne diseases has focused on vector control through habitat reduction and application of pesticides that kill mosquito larvae. However, in certain situations, public health officials control adult mosquito populations by spraying ultra-low volume (ULV) (<3 fluid ounces per acre [oz/acre]) mosquito-control (MC) pesticides, such as naled, permethrin, and d-phenothrin. These ULV applications generate aerosols of fine droplets of pesticides that stay aloft and kill mosquitoes on contact while minimizing the risk for exposure to persons, wildlife, and the environment. This report summarizes the results of studies in Mississippi, North Carolina, and Virginia that assessed human exposure to ULV naled, permethrin, and d-phenothrin used in emergency, large-scale MC activities. The findings indicated ULV application in MC activities did not result in substantial pesticide exposure to humans; however, public health interventions should focus on the reduction of home and workplace exposure to pesticides.

PTX-sensitive signals in bone marrow homing of fetal and adult hematopoietic progenitor cells

AbstractSeveral examples suggest a relationship between in vitro migratory capacity and bone marrow (BM) homing. Pertussis toxin (PTX) is a potent inhibitor of serpentine receptor–associated inhibitory trimeric guanidine nucleotide binding (Gi) protein signals. As such, it blocks hematopoietic progenitor cell migration in vitro, but contrary to expectation, no effects on BM homing were observed in previous studies. We therefore re-examined the effect of PTX on homing of murine BM and fetal liver (FL). We found that BM homing of PTX-incubated progenitor cells (colony-forming cells in culture [CFU-Cs]) from BM or FL in irradiated and nonirradiated recipients was reduced by more than 75%, with a concomitant increase in circulating CFU-Cs in peripheral blood. Additional studies confirmed the functional significance of this reduction in homing: PTX-treated cells did not provide radioprotection, and their short-term engraftment in BM and spleen was drastically reduced. Furthermore, several approaches show that cell-intrinsic rather than host-derived mechanisms are responsible for the PTX-induced homing defect. In summary, we show that Gi protein signals are required for BM homing and, as such, provide a new example of the association between BM homing and in vitro migration. Moreover, our data suggest that the behavior of hematopoietic progenitors in obeying Gi signaling does not diverge from that of mature leukocytes.

Impaired bone marrow homing of cytokine-activated CD34+ cells in the NOD/SCID model

AbstractThe reduced engraftment potential of hematopoietic stem/progenitor cells (HSPCs) after exposure to cytokines may be related to the impaired homing ability of actively cycling cells. We tested this hypothesis by quantifying the short-term homing of human adult CD34+ cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) animals. We show that the loss of engraftment ability of cytokine-activated CD34+ cells is associated with a reduction in homing of colony-forming cells (CFCs) to bone marrow (BM) at 24 hours after transplantation (from median 2.8% [range, 1.9%-6.1%] to 0.3% [0.0%-0.7%]; n = 3; P < .01), coincident with an increase in CFC accumulation in the lungs (P < .01). Impaired BM homing of cytokine-activated cells was not restored by using sorted cells in G0G1 or by inducing cell cycle arrest at the G1/S border. Blocking Fas ligation in vivo did not increase the BM homing of cultured cells. Finally, we tested cytokine combinations or culture conditions previously reported to restore the engraftment of cultured cells but did not find that any of these was able to reverse the changes in homing behavior of cytokine-exposed cells. We suggest that these changes in homing and, as a consequence, engraftment result from the increased migratory capacity of infused activated cells, leading to the loss of selectivity of the homing process.

Comment on ‘Some Evidence that a Tobin Tax on Foreign Exchange Transactions may Increase Volatility’

Global turnover in foreign exchange markets averaged $1.2 trillion per day according to the most recent estimates available from the Bank for International Settlements.1 Yet, cross-border trade of goods and services accounts for less than 5 percent of the total trading. While it is difficult to get precise estimates on hedging, roughly 20 percent of total trading is aimed at hedging against future exchange rate changes. The remaining roughly 75 percent of total turnover in global foreign exchange markets is believed to be related to short or long term exchange rate speculation. The large fraction of global turnover in currency markets that is unrelated to trade or hedging has lead economists and policy markets to the conjecture that speculation is responsible for the perceived recent increase in volatility in foreign exchange markets. Several economists, most prominently Nobel Laureate Dr. James Tobin, have advocated levying a tax (a “Tobin tax”) on foreign exchange transactions to reduce volatility induced by exchange rate speculation. Recently, several European countries spearheaded by France have debated a proposed legislation to impose a tax on currency transactions.2 However, to date, there is no strong empirical evidence that an increase in transactions costs (which would be the result of a Tobin tax) would significantly dampen volatility. On the contrary, Umlauf (1993) finds that a transactions tax on stock trading, the so called “puppy-tax”, imposed in Sweden between 1984 and 1991 actually caused an increase in volatility and a dramatic reduction in home-

Responding to out-of-hours demand: the extent and nature of urgent need.

Little research has been undertaken concerning GPs' perceptions about urgent or 'appropriate' out-of-hours demand. We aimed to measure GPs' perceptions about patients' need for urgent out-of-hours general medical help according to indicators of physical, psychological/emotional and social need, and the medical necessity of a home visit. Twenty-five practices participated in an audit and research study whereby GPs completed an audit form for all contacts during November/December 1995 and February/March 1996. Each contact was assessed according to the indicators of urgent need and GPs commented on reasons for making such assessments. Audit forms were completed on 1862 patients, and GPs considered that 66.6% (1027) of contacts had either a physically, psychologically/emotionally or socially urgent need for help and were uncertain about a further 10.7% (165). Over half (53.0%) were considered to have an urgent physical need, almost one-third (31.0%) to have an urgent psychological/emotional need and 10.1% (119) to have an urgent social need for help. Over half (55.2%) of visits were considered to be medically necessary, the majority of which (89.9%) were assessed as having an urgent physical need for help. The findings raise questions about the strategic direction of newer forms of service delivery (GP Co-operatives) and suggest the need for further research to inform the strategic reduction in home visiting, particularly in inner-city areas where many residents have little access to transport out-of-hours to enable them to attend a primary care centre. GP co-operatives are, however, well placed to improve interagency working and cross-referral to other health and social service personnel, and respond more 'appropriately' to some psychological/emotional and social problems.

Maintenance of allogeneic cell recognition in allograft tolerant mice

The organ distributions of 51Cr-labelled lymph node cells following transfer to syngeneic, allogeneic and specifically tolerant allogeneic recipients were compared. Neonatal induction of transplantation tolerance in several donor—recipient combinations involving different H-2 haplotypes had no effect on the reduction of homing into lymph nodes and the values of the homing did not differ from those of the untreated allogeneic recipients. In both cases, they amounted to 45–55% of the syngeneic controls. Even those neonatally treated animals, which had not been rendered tolerant at birth and rejected test skin grafts, were not capable of removing the transferred allogeneic cells by a typical immune elimination. The results indicate that animals recognize allogeneic cells, irrespective of whether or not they reject test skin grafts.