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Search Results: 1 - 10 of 406525 matches for " Justin M. Cohen "
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Predicting Global Fund grant disbursements for procurement of artemisinin-based combination therapies
Justin M Cohen, Inder Singh, Megan E O'Brien
Malaria Journal , 2008, DOI: 10.1186/1475-2875-7-200
Abstract: Predictive regression models estimating the timing and rate of disbursements from the Global Fund to recipient countries for each malaria grant were derived using a repeated split-sample procedure intended to avoid over-fitting. Predictions were compared against actual disbursements in a group of validation grants, and forecasts of ACT procurement extrapolated from disbursement predictions were evaluated against actual procurement in two sub-Saharan countries.Quarterly forecasts were correlated highly with actual smoothed disbursement rates (r = 0.987, p < 0.0001). Additionally, predicted ACT procurement, extrapolated from forecasted disbursements, was correlated strongly with actual ACT procurement supported by two grants from the Global Fund's first (r = 0.945, p < 0.0001) and fourth (r = 0.938, p < 0.0001) funding rounds.This analysis derived predictive regression models that successfully forecasted disbursement patterning for individual Global Fund malaria grants. These results indicate the utility of this approach for demand forecasting of ACT and, potentially, for other commodities procured using funding from the Global Fund. Further validation using data from other countries in different regions and environments will be necessary to confirm its generalizability.Since the 1970s, the rise of global resistance to the cheap, ubiquitous antimalarial chloroquine (CQ) has made it imperative to find new, effective drugs to fight Plasmodium falciparum, the parasite species responsible for a majority of malaria-related mortality worldwide. Modern artemisinin drugs were first developed by the Chinese for the Viet Cong during the Vietnam-American War, on the basis of ancient Chinese fever remedies involving Artemisia annua, the sweet wormwood plant. Artemisinin-based combination therapy (ACT), which utilizes artemisinin along with an additional partner drug, such as amodiaquine, lumefantrine or mefloquine, is now widely considered the most effective treatment for uncompl
A pharmacy too far? Equity and spatial distribution of outcomes in the delivery of subsidized artemisinin-based combination therapies through private drug shops
Cohen Justin M,Sabot Oliver,Sabot Kate,Gordon Megumi
BMC Health Services Research , 2010, DOI: 10.1186/1472-6963-10-s1-s6
Abstract: Background Millions of individuals with malaria-like fevers purchase drugs from private retailers, but artemisinin-based combination therapies (ACTs), the only effective treatment in regions with high levels of resistance to older drugs, are rarely obtained through these outlets due to their relatively high cost. To encourage scale up of ACTs, the Affordable Medicines Facility – malaria is being launched to subsidize their price. The Government of Tanzania and the Clinton Foundation piloted this subsidized distribution model in two Tanzanian districts to examine concerns about whether the intervention will successfully reach poor, rural communities. Methods Stocking of ACTs and other antimalarial drugs in all retail shops was observed at baseline and in four subsequent surveys over 15 months. Exit interviews were conducted with antimalarial drug customers during each survey period. All shops and facilities were georeferenced, and variables related to population density and proximity to distribution hubs, roads, and other facilities were calculated. To understand the equity of impact, shops stocking ACTs and consumers buying them were compared to those that did not, according to geographic and socioeconomic variables. Patterning in ACT stocking and sales was evaluated against that of other common antimalarials to identify factors that may have impacted access. Qualitative data were used to assess motivations underlying stocking, distribution, and buying disparities. Results Results indicated that although total ACT purchases rose from negligible levels to nearly half of total antimalarial sales over the course of the pilot, considerable geographic variation in stocking and sales persisted and was related to a variety of socio-spatial factors; ACTs were stocked more often in shops located closer to district towns (p<0.01) and major roads (p<0.01) and frequented by individuals of higher socioeconomic status (p<0.01). However, other antimalarial drugs displayed similar patterning, indicating the existence of underlying disparities in access to antimalarial drugs in general in these districts. Conclusions As this subsidy model is scaled up across multiple countries, these results confirm the potential for increased ACT usage but suggest that additional efforts to increase access in remote areas will be needed for the scale-up to have equitable impact. Trial registration Current Controlled Trials ISRCTN39125414.
A framework for assessing the feasibility of malaria elimination
Bruno Moonen, Justin M Cohen, Andy J Tatem, Jessica Cohen, Simon I Hay, Oliver Sabot, David L Smith
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-322
Abstract: During the Global Malaria Eradication Programme (GMEP) and the decade that followed, 37 countries with endemic malaria succeeded in eliminating transmission [1]. Since 1978, however, only nine more countries have reached this goal, while most malaria-endemic countries have aimed for control, not elimination [2]. Recently, some of the countries that halved their malaria cases between 2000 and 2008 [1] are revising their strategic plans and are considering elimination as an alternative to maintaining control measures indefinitely. In the wake of Bill and Melinda Gates' 2007 commitment to global malaria eradication [3,4], officials from many countries where elimination was considered infeasible during the GMEP because of high endemicity and poor infrastructure [5-7], including Nigeria [8], Ghana [9], Tanzania [10], and Kenya [11], have announced plans to eliminate malaria. It has been argued that premature commitment to elimination may be counterproductive as it could divert limited resources and negatively impact efforts to reduce the high burden of malaria [3,12,13]. There is thus an urgent need for clear, evidence-based guidance to assess whether elimination represents a realistic goal in a given region.Weighing elimination today is different from the beginning of the GMEP era, when the impact of eradication programs essentially was taken for granted. The spectacular early success of the GMEP in Europe [5,6,14,15] was not replicated elsewhere, however, and the early timelines and cost estimates proved overly optimistic [7]. The GMEP adapted by recommending that countries assess the feasibility of such an undertaking through "a preliminary study to accumulate and analyze the information required for realistic programme planning" before embarking on a costly and potentially ineffective campaign [16,17]. These studies were intended to "cover not only technical and operational aspects but also a wider sphere, with a view to elucidating the socio-economic implications of
“An Unusual Urological Tumour”: Above the Collar and below the Belt
Erik K. Mayer,Shabnam Undre,Daniel C. Cohen,Marjorie M. Walker,Justin A. Vale,Anup Patel
Case Reports in Oncological Medicine , 2012, DOI: 10.1155/2012/480826
Abstract: Bladder lymphomas are rarely primary tumours and more commonly associated with systemic lymphoma, either as nonlocalised bladder lymphoma or as secondary bladder lymphoma. Primary bladder lymphomas (PBL) tend to be low-grade mucosa-associated lymphoid tissue (MALT) type, contrasting with diffuse large cell or follicular centre cell types more commonly seen in secondary bladder lymphoma. Bladder involvement by systemic lymphoma infers poor prognosis and patients often have no localising symptoms (typically a postmortem diagnosis). Other treatments are preferred over surgery for all bladder lymphomas, except where diagnosis is uncertain or for relief of irritative bladder symptoms. We describe a unique case of systemic high-grade B-cell lymphoma with simultaneous cutaneous renal and bladder lesions at presentation.
Social Exclusion Modifies Climate and Deforestation Impacts on a Vector-Borne Disease
Luis Fernando Chaves ,Justin M. Cohen,Mercedes Pascual,Mark L. Wilson
PLOS Neglected Tropical Diseases , 2008, DOI: 10.1371/journal.pntd.0000176
Abstract: Background The emergence of American Cutaneous Leishmaniasis (ACL) has been associated with changes in the relationship between people and forests, leading to the view that forest ecosystems increase infection risk and subsequent proposal that deforestation could reduce re-emergence of this disease. Methodology/Principal Findings We analyzed county-level incidence rates of ACL in Costa Rica (1996–2000) as a function of social and environmental variables relevant to transmission ecology with statistical models that incorporate breakpoints. Once social marginality was taken into account, the effect of living close to a forest on infection risk was small, and diminished exponentially above a breakpoint. Forest cover was associated with the modulation of temporal effects of El Ni?o Southern Oscillation (ENSO) at small spatial scales, revealing an additional complex interplay of environmental forces and disease patterns. Conclusions/Significance Social factors, which previously have not been evaluated rigorously together with environmental and climatic factors, appear to play a critical role that may ultimately determine disease risk.
How absolute is zero? An evaluation of historical and current definitions of malaria elimination
Justin M Cohen, Bruno Moonen, Robert W Snow, David L Smith
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-213
Abstract: Since the goal of global malaria eradication was resurrected in 2007 [1], discussions of the proper aims of national malaria programs have been revitalized [2-4]. Today, global malaria eradication - or the permanent reduction to zero of the worldwide incidence of infection [5] - is considered infeasible with currently available tools [6], but 39 countries are contemplating elimination [7], generally defined in the same way as eradication but on a country or regional scale and thus necessitating continued measures to prevent reestablishment of transmission [5].Decisions to eliminate malaria involve a complex set of factors [8], and measuring malaria itself involves a number of uncertainties [9,10]. This complexity will be compounded by any ambiguity surrounding terminology. Despite the need for precise definitions [11], there has never existed universal agreement over the meaning of many terms of basic relevance to malaria programs [9]. Even during the Global Malaria Eradication Program (GMEP), debate raged over what, exactly, "eradication" meant. At one pole, Cockburn argued that "so long as a single member of the [pathogen] species survives, then eradication has not been accomplished" [12], a state that today is called "extinction" [13]. At the other, it was posited that "the aim of eradication of an infectious disease is its reduction to a level at which it ceases to constitute an important public health problem" [14], a definition closely aligned with what recently has been called "control" [3]. In between these extremes, eradication was defined as the "continued absence of transmission within a specified area," [15] including "the elimination of the reservoir of infective cases" [16], an explanation more in line with the current concept of "elimination" [13].Debates over the precise definitions of terms like "eradication," "elimination," and "control," are much more than semantic arguments. International donor agencies need measurable markers of progress to just
“An Unusual Urological Tumour”: Above the Collar and below the Belt
Erik K. Mayer,Shabnam Undre,Daniel C. Cohen,Marjorie M. Walker,Justin A. Vale,Anup Patel
Case Reports in Oncological Medicine , 2012, DOI: 10.1155/2012/480826
Abstract: Bladder lymphomas are rarely primary tumours and more commonly associated with systemic lymphoma, either as nonlocalised bladder lymphoma or as secondary bladder lymphoma. Primary bladder lymphomas (PBL) tend to be low-grade mucosa-associated lymphoid tissue (MALT) type, contrasting with diffuse large cell or follicular centre cell types more commonly seen in secondary bladder lymphoma. Bladder involvement by systemic lymphoma infers poor prognosis and patients often have no localising symptoms (typically a postmortem diagnosis). Other treatments are preferred over surgery for all bladder lymphomas, except where diagnosis is uncertain or for relief of irritative bladder symptoms. We describe a unique case of systemic high-grade B-cell lymphoma with simultaneous cutaneous renal and bladder lesions at presentation. 1. Case Report A 70-year-old man presented to the dermatologists with a 2-year history of painless enlarging scalp nodules, which had rapidly worsened over the previous 6 months (Figure 1(a)). He had lost 7?kg in weight; there were no other systemic symptoms. He had neither clinical lymphadenopathy nor hepatosplenomegaly and his peripheral blood count, ESR, protein electrophoresis, liver function tests, and LDH were normal. A skin biopsy from the scalp demonstrated high-grade B-cell non-Hodgkin’s lymphoma. Staging CT showed multiple small cervical lymphadenopathy, lymphomatous infiltration in both kidneys, and an area of mucosal thickening of the bladder, which was consistent with a primary bladder carcinoma. Staging was completed with an MRI of the head (Figure 1(b)) and bone marrow biopsy, which was normal. Figure 1: (a) Scalp nodules as seen at presentation. (b) MRI demonstrating an extensive mixed signal, soft tissue mass, over the vertex of the skull. There is infiltration through the inner and outer tables of the skull vault and extension into the dural membranes. The patient described neither lower urinary tract symptoms nor episodes of macroscopic haematuria and was a nonsmoker. A urine cytology specimen revealed atypical cells more consistent with lymphoid than epithelial/transitional cell origin (Figure 2(a)). At cystoscopy, a 3?cm round submucosal lesion on the anterior aspect of the bladder wall was seen and resected. Histology confirmed high-grade B-cell lymphoma in both bladder and kidney biopsies (Figure 2(b)). Figure 2: (a) Urine cytology demonstrates a cluster of atypical lymphoid cells. (b) Biopsy of bladder tumour showing infiltration of the transitional epithelium and lamina propria by atypical B lymphocytes (CD20 positive
Pulsed excitation dynamics of an optomechanical crystal resonator near its quantum ground-state of motion
Sean M. Meenehan,Justin D. Cohen,Gregory S. MacCabe,Francesco Marsili,Matthew D. Shaw,Oskar Painter
Physics , 2015, DOI: 10.1103/PhysRevX.5.041002
Abstract: Using pulsed optical excitation and read-out along with single phonon counting techniques, we measure the transient back-action, heating, and damping dynamics of a nanoscale silicon optomechanical crystal cavity mounted in a dilution refrigerator at a base temperature of 11mK. In addition to observing a slow (~740ns) turn-on time for the optical-absorption-induced hot phonon bath, we measure for the 5.6GHz `breathing' acoustic mode of the cavity an initial phonon occupancy as low as 0.021 +- 0.007 (mode temperature = 70mK) and an intrinsic mechanical decay rate of 328 +- 14 Hz (mechanical Q-factor = 1.7x10^7). These measurements demonstrate the feasibility of using short pulsed measurements for a variety of quantum optomechanical applications despite the presence of steady-state optical heating.
Local topographic wetness indices predict household malaria risk better than land-use and land-cover in the western Kenya highlands
Justin M Cohen, Kacey C Ernst, Kim A Lindblade, John M Vulule, Chandy C John, Mark L Wilson
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-328
Abstract: The topographic wetness index, an estimate of predicted water accumulation in a defined area, was generated from a digital terrain model of the landscape surrounding households in two neighbouring western Kenyan highland communities. Variables determined to best encompass the variance in this topographic wetness surface were calculated at a household level. Land-cover/land-use information was extracted from a high-resolution satellite image using an object-based classification method. Topographic and land-cover variables were used individually and in combination to predict household-level malaria in the communities through an iterative split-sample model fitting and testing procedure. Models with only topographic variables were compared to those with additional predictive factors related to land-cover/land-use to investigate whether these environmental factors improved prediction of malaria based on the shape of the land alone.Variables related to topographic wetness proved most useful in predicting the households of individuals contracting malaria in this region of rugged terrain. Other variables related to human modification of the environment also demonstrated clear associations with household malaria. However, these land-cover/land-use variables failed to produce unambiguous improvements in statistical predictive models controlling for important topographic factors, with none improving prediction of household-level malaria more than 75% of the time.Topographic wetness values in this region of highly varied terrain more accurately predicted houses at greater risk of malaria than did consideration of land-cover/land-use characteristics. As such, those planning control or local elimination strategies in similar highland regions may use topographic and geographic characteristics to effectively identify high-receptivity regions that may require enhanced vigilance.Local elimination of malaria requires identification of residual transmission foci [1], while optimal tar
Topography-derived wetness indices are associated with household-level malaria risk in two communities in the western Kenyan highlands
Justin M Cohen, Kacey C Ernst, Kim A Lindblade, John M Vulule, Chandy C John, Mark L Wilson
Malaria Journal , 2008, DOI: 10.1186/1475-2875-7-40
Abstract: Hydrologic modelling techniques were adapted to predict the flow of water across the landscape surrounding households in two communities in the western Kenyan highlands. These surface analyses were used to generate indices describing predicted water accumulation in regions surrounding the study area. Households with and without malaria were compared for their proximity to regions of high and low predicted wetness. Predicted wetness and elevation variables were entered into bivariate and multivariate regression models to examine whether significant associations with malaria were observable at small spatial scales.On average, malaria case households (n = 423) were located 280 m closer to regions with very high wetness indices than non-malaria "control" households (n = 895) (t = 10.35, p < 0.0001). Distance to high wetness indices remained an independent predictor of risk after controlling for household elevation in multivariate regression (OR = 0.93 [95% confidence interval = 0.89–0.96] for a 100 m increase in distance). For every 10 m increase in household elevation, there was a 12% decrease in the odds of the house having a malaria case (OR = 0.88 [0.85–0.90]). However, after controlling for distance to regions of high predicted wetness and the community in which the house was located, this reduction in malaria risk was not statistically significant (OR = 0.98 [0.94–1.03]).Proximity to terrain with high predicted water accumulation was significantly and consistently associated with increased household-level malaria incidence, even at small spatial scales with little variation in elevation variables. These results suggest that high wetness indices are not merely proxies for valley bottoms, and hydrologic flow models may prove valuable for predicting areas of high malaria risk in highland regions. Application in areas where malaria surveillance is limited could identify households at higher risk and help focus interventions.Elevation has long been recognized to be ass
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