Influence of residency training on the clinical reasoning development of Kenyan physiotherapists.

Objective: The purpose of this study was to explore the clinical reasoning development of physical therapists participating in an 18-month orthopaedic residency program in Nairobi, Kenya. Methods: A mixed methods research design was utilized. The participants' clinical reasoning was assessed through a live patient examination prior to entering the residency program and upon graduation. One-on-one interviews were performed with the residents to explore their clinical reasoning during the final examination. Results: Residents (n = 14) demonstrated a statistically significant improvement in their ability to perform an examination of a patient and determine a hypothetical diagnosis. The clinical reasoning process described by the participants included the hypothetical deductive and narrative reasoning models. The residents did not appear to incorporate pattern recognition during the patient assessment. Discussion: Similar to studies on novice and expert practice in physical therapy, residents demonstrated an improvement in cue acquisition, the ability to verify and refute a hypothetical diagnosis, and the ability to match interventions to patients impairments. In addition, the residents utilized a combination of clinical reasoning models during the examination and evaluation of the patient including hypothetical deductive reasoning and narrative reasoning. Level of Evidence: 4.

Covalent IR820-PEG-diamine nanoconjugates for theranostic applications in cancer.

Near-infrared dyes can be used as theranostic agents in cancer management, based on their optical imaging and localized hyperthermia capabilities. However, their clinical translatability is limited by issues such as photobleaching, short circulation times, and nonspecific biodistribution. Nanoconjugate formulations of cyanine dyes, such as IR820, may be able to overcome some of these limitations. We covalently conjugated IR820 with 6 kDa polyethylene glycol (PEG)-diamine to create a nanoconjugate (IRPDcov) with potential for in vivo applications. The conjugation process resulted in nearly spherical, uniformly distributed nanoparticles of approximately 150 nm diameter and zeta potential -0.4±0.3 mV. The IRPDcov formulation retained the ability to fluoresce and to cause hyperthermia-mediated cell-growth inhibition, with enhanced internalization and significantly enhanced cytotoxic hyperthermia effects in cancer cells compared with free dye. Additionally, IRPDcov demonstrated a significantly longer (P<0.05) plasma half-life, elimination half-life, and area under the curve (AUC) value compared with IR820, indicating larger overall exposure to the theranostic agent in mice. The IRPDcov conjugate had different organ localization than did free IR820, with potential reduced accumulation in the kidneys and significantly lower (P<0.05) accumulation in the lungs. Some potential advantages of IR820-PEG-diamine nanoconjugates may include passive targeting of tumor tissue through the enhanced permeability and retention effect, prolonged circulation times resulting in increased windows for combined diagnosis and therapy, and further opportunities for functionalization, targeting, and customization. The conjugation of PEG-diamine with a near-infrared dye provides a multifunctional delivery vector whose localization can be monitored with noninvasive techniques and that may also serve for guided hyperthermia cancer treatments.

Near-infrared fluorescing IR820-chitosan conjugate for multifunctional cancer theranostic applications.

This study reports the preparation and characterization of IR820-chitosan conjugates that have potential multifunctional imaging-hyperthermia applications in cancer. The conjugates were formulated by covalentcouplingofchitosan to a carboxyl derivatized IR820, and studied for optical imaging and hyperthermia applications. IR820-chitosan conjugates were able to generate heat upon exposure to 808nm laser and produce hyperthermic cell growth inhibition in cancer cell lines MES-SA, SKOV-3 and Dx5. The level of cell growth inhibition caused by hyperthermia was significantly higher for IR820-chitosan compared to IR820 in MES-SA and Dx5 cells. Fluorescent microscope images of these cancer cell lines after 3-h exposure to 5µM IR820-chitosan showed that the conjugates can be used for in vitro near-infrared imaging. In an in vivo rat model, the conjugates accumulated in the liver after i.v. injection and were excreted through the gastrointestinal tract, demonstrating a different biodistribution when compared to the free dye. The accumulation of these conjugates in bile with subsequent gastrointestinal excretion allows for potential applications as gastrointestinal contrast agents and delivery vehicles. This formulation can potentially be used in multifunctional cancer theranostics.

Nanoplexes for cell imaging and hyperthermia: in vitro studies.

Novel IR820-polyethylene glycol-diamine nanoplexes (IR820-PDNCs) have potential multifunctional imaging-hyperthermia applications in cancer. Nanoplexes were formulated by ionic interaction and characterized in vitro for their imaging and hyperthermia capabilities. The resulting nanoplexes were approximately 50 nm diameter, with a zeta potential of 2.0 +/- 0.9 mV, and able to generate heat upon exposure to 808 nm laser. Cytotoxicity studies in SKOV-3, MES-SA and Dx5 cancer cell lines demonstrate comparable cytotoxicity of IR820-PDNCs versus free IR820 after 24 hours. The nanoplexes are able to produce hyperthermic cell growth inhibition in all three cancer cell lines after excitation with laser. The level of cell growth inhibition caused by hyperthermia is significantly higher for IR820-PDNCs compared to IR820 in MES-SA and Dx5 cells. Fluorescent microscope images after 2.5-hour exposure to 5 microM IR820-PDNCs or 5 microM free IR820 show increased uptake for IR820-PDNCs compared to free IR820, especially for SKOV-3 and Dx5 cancer cells. This formulation can potentially be used in multifunctional cancer theranostics.

Comparative study of the optical and heat generation properties of IR820 and indocyanine green.

AbstractNear-infrared (NIR) fluorophores are the focus of extensive research for combined molecular imaging and hyperthermia. In this study, we showed that the cyanine dye IR820 has optical and thermal generation properties similar to those of indocyanine green (ICG) but with improved in vitro and in vivo stability. The fluorescent emission of IR820 has a lower quantum yield than ICG but less dependence of the emission peak location on concentration. IR820 demonstrated degradation half-times approximately double those of ICG under all temperature and light conditions in aqueous solution. In hyperthermia applications, IR820 generated lower peak temperatures than ICG (4-9%) after 3-minute laser exposure. However, there was no significant difference in hyperthermia cytotoxicity, with both dyes causing significant cell growth inhibition at concentrations ≥ 5 µM. Fluorescent images of cells with 10 µM IR820 were similar to ICG images. In rats, IR820 resulted in a significantly more intense fluorescence signal and significantly higher organ dye content than for ICG 24 hours after intravenous dye administration (p < .05). Our study shows that IR820 is a feasible agent in experimental models of imaging and hyperthermia and could be an alternative to ICG when greater stability, longer image collection times, or more predictable peak locations are desirable.

Simultaneous delivery of chemotherapeutic and thermal-optical agents to cancer cells by a polymeric (PLGA) nanocarrier: an in vitro study.

PURPOSE: To test the effectiveness of a dual-agent-loaded PLGA nanoparticulate drug delivery system containing doxorubicin (DOX) and indocyanine green (ICG) in a DOX-sensitive cell line and two resistant cell lines that have different resistance mechanisms. METHODS: The DOX-sensitive MES-SA uterine sarcoma cell line was used as a negative control. The two resistant cell lines were uterine sarcoma MES-SA/Dx5, which overexpresses the multidrug resistance exporter P-glycoprotein, and ovarian carcinoma SKOV-3, which is less sensitive to doxorubicin due to a p53 gene mutation. The cellular uptake, subcellular localization and cytotoxicity of the two agents when delivered via nanoparticles (NPs) were compared to their free-form administration. RESULTS: The cellular uptake and cytotoxicity of DOX delivered by NPs were comparable to the free form in MES-SA and SKOV-3, but much higher in MES-SA/Dx5, indicating the capability of the NPs to overcome P-glycoprotein resistance mechanisms. NP-encapsulated ICG showed slightly different subcellular localization, but similar fluorescence intensity when compared to free ICG, and retained the ability to generate heat for hyperthermia delivery. CONCLUSION: The dual-agent-loaded system allowed for the simultaneous delivery of hyperthermia and chemotherapy, and this combinational treatment greatly improved cytotoxicity in MES-SA/Dx5 cells and to a lesser extent in SKOV-3 cells.