Recruiting and retaining GPs and patients in intervention studies: the DEPS-GP project as a case study

Background: Recruiting and retaining GPs for research can prove difficult, and may result in sub-optimal patient participation where GPs are required to recruit patients. Low participation rates may affect the validity of research. This paper describes a multi-faceted approach to maximise participation of GPs and their patients in intervention studies, using an Australian randomised controlled trial of a depression/suicidality management intervention as a case study. The paper aims to outline experiences that may be of interest to others considering engaging GPs and/or their patients in primary care studies. Methods: A case study approach is used to describe strategies for: (a) recruiting GPs; (b) encouraging GPs to recruit patients to complete a postal questionnaire; and (c) encouraging GPs to recruit patients as part of a practice audit. Participant retention strategies are discussed in light of reasons for withdrawal. Results: The strategies described, led to the recruitment of a higher than expected number of GPs (n = 772). Three hundred and eighty three GPs (49.6%) followed through with the intent to participate by sending out a total of 77,820 postal questionnaires, 22,251 (28.6%) of which were returned. Three hundred and three GPs (37.0%) participated in the practice audit, which aimed to recruit 20 patients per participating GP (i.e., a total of 6,060 older adults). In total, 5,143 patients (84.9%) were represented in the audit. Conclusion: Inexpensive methods were chosen to identify and recruit GPs; these relied on an existing database, minor promotion and a letter of invitation. Anecdotally, participating GPs agreed to be involved because they had an interest in the topic, believed the study would not impinge too greatly on their time, and appreciated the professional recognition afforded by the Continuing Professional Development (CPD) points associated with study participation. The study team established a strong rapport with GPs and their reception staff, offered clear instructions, and were as flexible and helpful as possible to retain GP participants. Nonetheless, we experienced attrition due to GPs' competing demands, eligibility, personnel issues and the perceived impact of the study on patients. A summary of effective and ineffective methods for recruitment and retention is provided.Michelle K Williamson, Jane Pirkis, Jon J Pfaff, Orla Tyson, Moira Sim, Ngaire Kerse, Nicola T Lautenschlager, Nigel P Stocks and Osvaldo P Almeid

Numerical methods for the design and description of in vitro expansion processes of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are a valuable source of cells for clinical applications (e.g., treatment of acute myocardial infarction or inflammatory diseases), especially in the field of regenerative medicine. However, for autologous (patient-specific) and allogeneic (off-the-shelf) hMSC-based therapies, in vitro expansion is necessary prior to the clinical application in order to achieve the required cell numbers. Safe, reproducible, and economic in vitro expansion of hMSCs for autologous and allogeneic therapies can be problematic because the cell material is restricted and the cells are sensitive to environmental changes. It is beneficial to collect detailed information on the hydrodynamic conditions and cell growth behavior in a bioreactor system, in order to develop a so called “Digital Twin” of the cultivation system and expansion process. Numerical methods, such as Computational Fluid Dynamics (CFD) which has become widely used in the biotech industry for studying local characteristics within bioreactors or kinetic growth modelling, provide possible solutions for such tasks. In this review, we will present the current state-of-the-art for the in vitro expansion of hMSCs. Different numerical tools, including numerical fluid flow simulations and cell growth modelling approaches for hMSCs, will be presented. In addition, a case study demonstrating the applicability of CFD and kinetic growth modelling for the development of an microcarrier-based hMSC process will be shown

Delayed flood for management of rice water weevil (Coleoptera: Curculionidae)

Draining and reestablishment of permanent flood has been used to prevent injury caused by larvae of the rice water weevil, Lissorhoptrus orjzophilus Kuschel. However, there are negative effects associated with this management practice such as loss of weed control and nitrogen, which necessitate the reapplication of herbicide and nitrogen followed by the reestablishment of permanent flood. An alternative to draining rice, Oryza sativa L., fields for rice water weevil management is to simply delay the establishment of the permanent flood. Delayed flood avoids problems associated with draining and reflooding fields. The primary objective of this study was to evaluate the efficacy of delayed flood for rice water weevil management and its impact on weed management using a herbicide resistant rice line. Use of herbicide resistant rice lines enables the application of delayed flood for rice water weevil management because of an increased spectrum of herbicidal activity against weeds. Delaying flood significantly reduced and delayed rice water weevil larval populations, providing an alternative cultural practice for rice water weevil management. Significantly improved management of noxious weeds was also observed without additional herbicide inputs. We anticipate that the yield gain from rice water weevil management without an insecticide application and with reduced (or altered) herbicide applications will be such that the potential yield loss from delayed flooding (as a result of possible physiological stress on the rice plant) will be offset

Delayed Flood for Management of Rice Water Weevil (Coleoptera: Curculionidae)

Draining and reestablishment of permanent flood has been used to prevent injury caused by larvae of the rice water weevil, Lissorhoptrus orjzophilus Kuschel. However, there are negative effects associated with this management practice such as loss of weed control and nitrogen, which necessitate the reapplication of herbicide and nitrogen followed by the reestablishment of permanent flood. An alternative to draining rice, Oryza sativa L., fields for rice water weevil management is to simply delay the establishment of the permanent flood. Delayed flood avoids problems associated with draining and reflooding fields. The primary objective of this study was to evaluate the efficacy of delayed flood for rice water weevil management and its impact on weed management using a herbicide resistant rice line. Use of herbicide resistant rice lines enables the application of delayed flood for rice water weevil management because of an increased spectrum of herbicidal activity against weeds. Delaying flood significantly reduced and delayed rice water weevil larval populations, providing an alternative cultural practice for rice water weevil management. Significantly improved management of noxious weeds was also observed without additional herbicide inputs. We anticipate that the yield gain from rice water weevil management without an insecticide application and with reduced (or altered) herbicide applications will be such that the potential yield loss from delayed flooding (as a result of possible physiological stress on the rice plant) will be offset