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The discovery of magic-sized clusters as intermediates in the synthesis of colloidal quantum dots has allowed for insight into formation pathways and provided atomically precise molecular platforms for studying the structure and surface chemistry of those materials. The synthesis of monodisperse InAs quantum dots has been developed through the use of indium carboxylate and As(SiMe3)3 as precursors and documented to proceed through the formation of magic-sized intermediates. Herein, we report the synthesis, isolation, and single-crystal X-ray diffraction structure of an InAs nanocluster that is ubiquitous across reports of InAs quantum dot synthesis. The structure, In26As18(O2CR)24(PR'3)3, differs substantially from previously reported semiconductor nanocluster structures even within the III-V family. However, it can be structurally linked to III-V and II-VI cluster structures through the anion sublattice. Further analysis using variable temperature absorbance spectroscopy and support from computation deepen our understanding of the reported structure and InAs nanomaterials as a whole.
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BACKGROUND AND PURPOSE: Unlike in Europe and Japan, guidelines or recommendations from specialized radiological societies on workflow management and adaptive intervention to reduce error rates are currently lacking in the United States. This study of neuroradiologic reads at a large US academic medical center, which may hopefully contribute to this discussion, found a direct relationship between error rate and shift volume. MATERIALS AND METHODS: CT and MR imaging reports from our institution's Neuroradiology Quality Assurance database (years 2014-2020) were searched for attending physician errors. Data were collected on shift volume specific error rates per 1000 interpreted studies and RADPEER scores. Optimal cutoff points for 2, 3 and 4 groups of shift volumes were computed along with subgroups' error rates. RESULTS: A total of 643 errors were found, 91.7% of which were clinically significant (RADPEER 2b, 3b). The overall error rate (errors/1000 examinations) was 2.36. The best single shift volume cutoff point generated 2 groups: ≤ 26 studies (error rate 1.59) and > 26 studies (2.58; OR: 1.63, P < .001). The best 2 shift volume cutoff points generated 3 shift volume groups: ≤ 19 (1.34), 20-28 (1.88; OR: 1.4, P = .1) and ≥ 29 (2.6; OR: 1.94, P < .001). The best 3 shift volume cutoff points generated 4 groups: ≤ 24 (1.59), 25-66 (2.44; OR: 1.54, P < .001), 67-90 (3.03; OR: 1.91, P < .001), and ≥ 91 (2.07; OR: 1.30, P = .25). The group with shift volume ≥ 91 had a limited sample size. CONCLUSIONS: Lower shift volumes yielded significantly lower error rates. The lowest error rates were observed with shift volumes that were limited to 19-26 studies. Error rates at shift volumes between 67-90 studies were 226% higher, compared with the error rate at shift volumes of ≤ 19 studies.
Subject(s)
Radiology , Humans , United States , Magnetic Resonance Imaging , Europe , JapanABSTRACT
Indium phosphide quantum dots have become an industrially relevant material for solid-state lighting and wide color gamut displays. The synthesis of indium phosphide quantum dots from indium carboxylates and tris(trimethylsilyl)phosphine (P(SiMe3)3) is understood to proceed through the formation of magic-sized clusters, with In37P20(O2CR)51 being the key isolable intermediate. The reactivity of the In37P20(O2CR)51 cluster is a vital parameter in controlling the conversion to quantum dots. Herein, we report structural perturbations of In37P20(O2CR)51 clusters induced by tuning the steric properties of a series of substituted phenylacetate ligands. This approach allows for control over reactivity with P(SiMe3)3, where meta-substituents enhance the susceptibility to ligand displacement, and para-substituents hinder phosphine diffusion to the core. Thermolysis studies show that with complete cluster dissolution, steric profile can modulate the nucleation period, resulting in a nanocrystal size dependence on ligand steric profile. The enhanced stability from ligand engineering also allows for the isolation and structural characterization by single-crystal X-ray diffraction of a new III-V magic-sized cluster with the formula In26P13(O2CR)39. This intermediate precedes the In37P20(O2CR)51 cluster on the InP QD reaction coordinate. The physical and electronic structure of this cluster are analyzed, providing new insight into previously unrecognized relationships between II-VI and III-V materials and the discrete growth of III-V cluster intermediates.
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This paper describes coinage-metal-doped InP quantum dots (QDs) as a platform for enhanced electron transfer to molecular acceptors relative to undoped QDs. A synthetic strategy is developed to prepare doped InP/ZnSe QDs. First-principles DFT calculations show that Ag+ and Cu+ dopants localize photoexcited holes while leaving electrons delocalized. This charge carrier wave function modulation is leveraged to enhance electron transfer to molecular acceptors by up to an order of magnitude. Examination of photoluminescence quenching data suggests that larger electron acceptors, such as anthraquinone and methyl viologen, bind to the QD surface in two ways: by direct adsorption to the surface and by adsorption following displacement of a weakly bound surface cation-ligand complex. Reactions with larger acceptors show the greatest increases in electron transfer between doped and undoped quantum dots, while smaller acceptors show smaller enhancements. Specifically, benzoquinone shows the smallest, followed by naphthoquinone and then methyl viologen and anthraquinone. These results demonstrate the benefits of dopant-induced excited-state carrier localization on photoinduced charge transfer and highlight design principles for improved implementation of quantum dots in photoredox catalysis.
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BACKGROUND: Neurocysticercosis (NCC) is a parasitic infection of the brain caused by ingesting water or food contaminated with tapeworm eggs. When it presents as a solitary mass, differentiation from a primary brain tumor on imaging can be difficult. Magnetic resonance imaging (MRI)-derived relative cerebral blood volume (rCBV) is a newer imaging technique used to identify areas of neovascularization in tumors, which may advance the differential diagnosis. OBSERVATIONS: A 25-year-old male presented after a seizure. Computed tomography (CT) and MRI demonstrated a partially enhancing lesion with microcalcifications and vasogenic edema. Follow-up rCBV assessment demonstrated mild hyperperfusion and/or small vessels at the lesional margins consistent with either an intermediate grade glioma or infection. Given the radiological equipoise, surgical accessibility, and differential diagnosis including primary neoplasm, metastatic disease, NCC, and abscess, resection was pursued. The calcified mass was excised en bloc and was confirmed as larval-stage NCC. LESSONS: CT or MRI may not always provide sufficient information to distinguish NCC from brain tumors. Although reports have suggested that rCBV may aid in identifying NCC, here the authors describe a case of pathologically confirmed NCC in which preoperative, qualitative, standardized rCBV findings raised concern for a primary neoplasm. This case documents the first standardized rCBV values reported in a pathologically confirmed case of NCC in the United States.
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Environmental circumstances shaping soil microbial communities have been studied extensively. However, due to disparate study designs, it has been difficult to resolve whether a globally consistent set of predictors exists, or context-dependency prevails. Here, we used a network of 18 grassland sites (11 of those containing regional plant productivity gradients) to examine (i) if similar abiotic or biotic factors predict both large-scale (across sites) and regional-scale (within sites) patterns in bacterial and fungal community composition, and (ii) if microbial community composition differs consistently at two levels of regional plant productivity (low vs. high). Our results revealed that bacteria were associated with particular soil properties (such as base saturation) and both bacteria and fungi were associated with plant community composition across sites and within the majority of sites. Moreover, a discernible microbial community signal emerged, clearly distinguishing high and low-productivity soils across different grasslands independent of their location in the world. Hence, regional productivity differences may be typified by characteristic soil microbial communities across the grassland biome. These results could encourage future research aiming to predict the general effects of global changes on soil microbial community composition in grasslands and to discriminate fertile from infertile systems using generally applicable microbial indicators.
Subject(s)
Grassland , Microbiota , Soil Microbiology , Microbiota/genetics , Fungi/genetics , Bacteria/genetics , Plants/microbiology , SoilABSTRACT
Magnetic resonance imaging (MRI) and clinicopathological tools have led to the identification of a wide spectrum of autoimmune entities that involve the spine. A clearer understanding of the unique imaging features of these disorders, along with their clinical presentations, will prove invaluable to clinicians and potentially limit the need for more invasive procedures such as tissue biopsies. Here, we review various autoimmune diseases affecting the spine and highlight salient imaging features that distinguish them radiologically from other disease entities.
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Fluorescent nanodiamonds, that is, those containing optically active defects, have attracted interest for their ability to be used as qubits; for in vivo imaging; and as sensors for spin, stress, and temperature. One of the most commonly studied nanodiamond color centers is the nitrogen vacancy. However, there is strong interest in discovering other impurity centers that provide localized midband gap transitions. Noble gas atoms have garnered attention since they have been discovered within nanodiamonds produced through high-pressure-high-temperature laser-heated diamond anvil cell synthesis methods, where they are commonly used as hydrostatic pressure media. Noble gas atoms that exist in macrosized natural or synthetic diamonds have been shown to be able to form color centers. This research uses ab initio density functional theory and cluster models to systematically study the localized electronic structure for group VIII impurities of nanodiamond, including helium, neon, argon, krypton, and xenon. An in-depth examination of the interaction between the noble gas atom and diamond lattice has been carried out. The changes to the vibrational and UV/vis absorption spectra have been analyzed. It was determined that the energetically preferred geometry is dependent on the atom size. Most noble gas defects are stabilized within the nanodiamond lattice and exist in tetrahedral interstitial positions, except for the largest noble gas studied in this work, Xe, which was determined to prefer a substitutional configuration. Both Kr and Xe are expected to be able to manifest visible/near-IR optical responses when included in the diamond lattice.
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Lesions of the central nervous system (CNS) can present with numerous and overlapping radiographical and clinical features that make diagnosis difficult based exclusively on history, physical examination, and traditional imaging modalities. Given that there are significant differences in optimal treatment protocols for these various CNS lesions, rapid and non-invasive diagnosis could lead to improved patient care. Recently, various advanced magnetic resonance imaging (MRI) techniques showed promising methods to differentiate between various tumors and lesions that conventional MRI cannot define by comparing their physiologic characteristics, such as vascularity, permeability, oxygenation, and metabolism. These advanced MRI techniques include dynamic susceptibility contrast MRI (DSC), diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI, Golden-Angle Radial Sparse Parallel imaging (GRASP), Blood oxygen level-dependent functional MRI (BOLD fMRI), and arterial spin labeling (ASL) MRI. In this article, a narrative review is used to discuss the current trends in advanced MRI techniques and potential future applications in identifying difficult-to-distinguish CNS lesions. Advanced MRI techniques were found to be promising non-invasive modalities to differentiate between paraganglioma, schwannoma, and meningioma. They are also considered promising methods to differentiate gliomas from lymphoma, post-radiation changes, pseudoprogression, demyelination, and metastasis. Advanced MRI techniques allow clinicians to take advantage of intrinsic biological differences in CNS lesions to better identify the etiology of these lesions, potentially leading to more effective patient care and a decrease in unnecessary invasive procedures. More clinical studies with larger sample sizes should be encouraged to assess the significance of each advanced MRI technique and the specificity and sensitivity of each radiologic parameter.
Subject(s)
Brain Neoplasms , Central Nervous System Neoplasms , Glioma , Meningeal Neoplasms , Humans , Brain Neoplasms/metabolism , Magnetic Resonance Imaging/methods , Glioma/metabolismABSTRACT
We demonstrate colloidal, layer-by-layer growth of metal oxide shells on InP quantum dots (QDs) at room temperature. We show with computational modeling that native InP QD surface oxides give rise to nonradiative pathways due to the presence of surface-localized dark states near the band edges. Replacing surface indium with zinc to form a ZnO shell results in reduced nonradiative decay and a density of states at the valence band edge that resembles defect-free, stoichiometric InP. We then developed a synthetic strategy using stoichiometric amounts of common atomic layer deposition precursors in alternating cycles to achieve layer-by-layer growth. Metal-oxide-shelled InP QDs show bulk and local structural perturbations as determined by X-ray diffraction and extended X-ray absorption fine structure spectroscopy. Upon growing ZnSe shells of varying thickness on the oxide-shelled QDs, we observe increased photoluminescence (PL) quantum yields and narrowing of the emission linewidths that we attribute to decreased ion diffusion to the shell, as supported by phosphorus X-ray emission spectroscopy. These results present a versatile strategy to control QD interfaces for novel heterostructure design by leveraging surface oxides. This work also contributes to our understanding of the connections between structural complexity and PL properties in technologically relevant colloidal optoelectronic materials.
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BACKGROUND. Numerous studies have explored factors associated with diagnostic errors in neuroradiology; however, large-scale multivariable analyses are lacking. OBJECTIVE. The purpose of this study was to evaluate associations of interpretation time, shift volume, care setting, day of week, and trainee participation with diagnostic errors by neuroradiologists at a large academic medical center. METHODS. This retrospective case-control study using a large tertiary-care academic medical center's neuroradiology quality assurance database evaluated CT and MRI examinations for which neuroradiologists had assigned RADPEER scores. The database was searched from January 2014 through March 2020 for examinations without (RADPEER score of 1) or with (RADPEER scores of 2a, 2b, 3a, 3b, or 4) diagnostic error. For each examination with error, two examinations without error were randomly selected (unless only one examination could be identified) and matched by interpreting radiologist and examination type to form case and control groups. Marginal mixed-effects logistic regression models were used to assess associations of diagnostic error with interpretation time (number of minutes since the immediately preceding report's completion), shift volume (number of examinations interpreted during the shift), emergency/inpatient setting, weekend interpretation, and trainee participation in interpretation. RESULTS. The case group included 564 examinations in 564 patients (mean age, 50.0 ± 25.0 [SD] years; 309 men, 255 women); the control group included 1019 examinations in 1019 patients (mean age, 52.5 ± 23.2 years; 540 men, 479 women). In the case versus control group, mean interpretation time was 16.3 ± 17.2 [SD] minutes versus 14.8 ± 16.7 minutes; mean shift volume was 50.0 ± 22.1 [SD] examinations versus 45.4 ± 22.9 examinations. In univariable models, diagnostic error was associated with shift volume (OR = 1.22, p < .001) and weekend interpretation (OR = 1.60, p < .001) but not interpretation time, emergency/inpatient setting, or trainee participation (p > .05). However, in multivariable models, diagnostic error was independently associated with interpretation time (OR = 1.18, p = .003), shift volume (OR = 1.27, p < .001), and weekend interpretation (OR = 1.69, p = .02). In subanalysis, diagnostic error showed independent associations on weekdays with interpretation time (OR = 1.18, p = .003) and shift volume (OR = 1.27, p < .001); such associations were not observed on weekends (interpretation time: p = .62; shift volume: p = .58). CONCLUSION. Diagnostic errors in neuroradiology were associated with longer interpretation times, higher shift volumes, and weekend interpretation. CLINICAL IMPACT. These findings should be considered when designing work-flow-related interventions seeking to reduce neuroradiology interpretation errors.
Subject(s)
Academic Medical Centers , Radiologists , Male , Humans , Female , Adult , Middle Aged , Aged , Case-Control Studies , Retrospective Studies , Diagnostic ErrorsABSTRACT
Chromium iodide monolayers, which have different magnetic properties in comparison to the bulk chromium iodide, have been shown to form skyrmionic states in applied electromagnetic fields or in Janus-layer devices. In this work, we demonstrate that spin-canted solutions can be induced into monolayer chromium iodide by select substitution of iodide atoms with isovalent impurities. Several concentrations and spatial configurations of halide substitutional defects are selected to probe the coupling between the local defect-induced geometric distortions and orientation of chromium magnetic moments. This work provides atomic-level insight into how atomically precise chemical doping can be used to create and control complex magnetic patterns in chromium iodide layers and lays out the foundation for investigating the field- and geometric-dependent magnetic properties in similar two-dimensional materials.
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We demonstrate fine-tuning of the atomic composition of InP/ZnSe quantum dots (QDs) at the core/shell interface. Specifically, we control the stoichiometry of both anions (P, As, S, and Se) and cations (In and Zn) at the InP/ZnSe core/shell interface and correlate these changes with the resultant steady-state and time-resolved optical properties of the nanocrystals. The use of reactive trimethylsilyl reagents results in surface-limited reactions that shift the nanocrystal stoichiometry to anion-rich and improve epitaxial growth of the shell layer. In general, anion deposition on the InP QD surface results in a redshift in the absorption, quenching of the excitonic photoluminescence, and a relative increase in the intensity of broad trap-based photoluminescence, consistent with delocalization of the exciton wavefunction and relaxation of exciton confinement. Time-resolved photoluminescence data for the resulting InP/ZnSe QDs show an overall small change in the decay dynamics on the ns timescale, suggesting that the relatively low photoluminescence quantum yields may be attributed to the creation of new thermally activated charge trap states and likely a dark population that is inseparable from the emissive QDs. Cluster-model density functional theory calculations show that the presence of core/shell interface anions gives rise to electronic defects contributing to the redshift in the absorption. These results highlight a general strategy to atomistically tune the interfacial stoichiometry of InP QDs using surface-limited reaction chemistry allowing for precise correlations with the electronic structure and photophysical properties.
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Magnetic circular dichroism (MCD) spectra are able to provide insights into the geometric, electronic, and magnetic properties of chemical systems. However, they can be challenging to understand and simulate given the need to simultaneously treat both the finite magnetic and optical fields. Thus, efficient simulations are desired to understand the spectra and resolve the molecular electronic states. Real-time dynamics are used widely in the simulation of electronic spectroscopies such as absorption as well as electronic circular dichroism, but simulating MCD with real-time dynamics is technically and theoretically challenging. In this work, we introduce a real-time dynamics-based ab initio method with a nonperturbative treatment of a static magnetic field with London orbitals for simulating the MCD spectra of closed shell systems. Effects of a magnetic field are included variationally in the spin-free nonrelativistic Hamiltonian. Real-time time-dependent density functional theory dynamics are then performed, from which we compute the response function in the presence of the external magnetic field, giving the MCD spectrum. The method developed in this paper is applied to simulate the MCD spectra for pyrimidine, pyrazine, and 1,4-naphthoquinone. Results are discussed and compared to the experiment.
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Developing interfacial probes of ligand-nanocluster interactions is crucial for understanding and tailoring the optoelectronic properties of these emerging nanomaterials. Using transient IR spectroscopy, we demonstrate that ligand vibrational modes of oleate-capped 1.3 nm InP nanoclusters report on the photogenerated exciton. The exciton induces an intensity change in the asymmetric carboxylate stretching mode by 57% while generating no appreciable shift in frequency. Thus, the observed difference signal is attributed to an exciton-induced change in the dipole magnitude of the asymmetric carboxylate stretching mode. Additionally, the transient IR data reveal that the infrared dipole change is dependent on the geometry of the ligand bound to the nanocluster. The experimental results are interpreted using TDDFT calculations, which identify how the spatial dependence of an exciton-induced electron density shift affects the vibrational motion of the carboxylate anchors. More broadly, this work demonstrates transient IR spectroscopy as a useful method for characterizing ligand-nanocluster coupling interactions.
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While some countries disaggregate N2O emission factors for urine and dung deposited onto pastures, in Canada, distinct N2O emission factors for beef cattle urine and dung have not been defined. To help address this knowledge gap, we conducted a 1-year study to quantify N2O fluxes from beef cattle urine and dung patches on a semiarid tame pasture in western Canada, as well as to quantify the N2O emission factors (EF3) for urine and dung as the percentage of applied N emitted as N2O-N. Urine and dung were deposited when soil water-filled pore space was nearly 60%, a wet soil condition for the grazing season in the semiarid study region, which led to a burst of N2O from urine in the first 14 days of the study (42% of total N emitted). Urine emitted more cumulative N2O (P < 0.001) and had a greater N2O emission factor (P = 0.002) than dung. The urine patch emitted 1.30 ± 0.47 g N2O-N m-2 year-1, while the dung patch emitted 0.083 ± 0.020 g N2O-N m-2 year-1 (mean values ± SD). The N2O emission factor for urine was 1.32 ± 0.49%, while for dung it was 0.03 ± 0.02%. We conclude that more study is needed to determine if distinct N2O emission factors are required for urine and dung deposited onto pasture in western Canada to more accurately estimate national N2O inventories.
Subject(s)
Cattle , Environmental Monitoring , Feces/chemistry , Nitrous Oxide/analysis , Urine/chemistry , Air Pollutants/analysis , Animals , Canada , Grassland , SoilABSTRACT
OBJECTIVE: The purpose of this study was to investigate the efficacy of ultrasonography to confirm Schanz pin placement in a cadaveric model, and the interobserver repeatability of the ultrasound methodology. DESIGN: This investigation is a repeated measures cadaveric study with multiple examiners. PARTICIPANTS: Cadaveric preparation and observations were done by an orthopaedic traumatologist and resident, and two general surgery traumatologists. INTERVENTIONS: A total of 16 Schanz pins were equally placed in bilateral femora and tibiae. Four examiners took measurements of pin protrusion beyond the distal cortices using first ultrasonography and then by direct measurement after gross dissection. MAIN OUTCOME MEASURE(S): Distal Schanz pin protrusion length measurements from both ultrasonography and direct measurement post dissection. RESULTS: Schanz pin protrusion measurements are underestimated by ultrasonography (p < 0.01) by an average of 10 percent over the range of 5 to 18 mm, and they display a proportional bias that increases the under reporting as the magnitude of pin protrusion increases. Ultrasound data demonstrate good linear correlation and closely represent actual protrusion values in the 5 to 12 mm range. Interobserver repeatability analysis demonstrated that all examiners were not statistically different in their measurements despite minimal familiarity with the ultrasound methodology (p > 0.8). CONCLUSIONS: Despite the statistical imparity of pin protrusion measurement via ultrasound compared to that of gross dissection, a consideration of the clinical relevance of ultrasound measurement bias during an austere operating theatre leads to the conclusion that ultrasonography is an adequate methodology for Schanz pin protrusion measurement.
Subject(s)
Bone Nails , Femoral Fractures/diagnostic imaging , Fracture Fixation , Point-of-Care Systems , Tibial Fractures/diagnostic imaging , Ultrasonography/instrumentation , Cadaver , External Fixators , Femoral Fractures/surgery , Humans , Reproducibility of Results , Tibial Fractures/surgeryABSTRACT
Growing orthopedic and nonorthopedic literature illustrates the point that having health insurance does not equal having access to care. The goal of this study was to evaluate the burden placed on patients to gain access to outpatient orthopedic care. For this study, burden was quantified as the distance traveled by the patient to be seen in clinic. This study was a retrospective review of all new patient encounters at an adult orthopedic outpatient clinic in an academic tertiary referral center over 1 calendar year. All patients were stratified into 4 categories: commercial/private insurance, Medic-aid, Medicare, and uninsured/private pay. The average distance traveled by each patient to the center was then calculated based on the patient's billing zip code. Patient visits were further stratified based on whether the patients were seen by 1 of 3 different categories of providers: general orthopedics/adult reconstruction, spine, and sports/upper extremity. The study group comprised 774 (31.1%) Medicaid patients, 653 (26.2%) Medicare patients, 917 (36.8%) commercial/private insurance patients, and 146 (5.9%) uninsured/private pay patients. The average 1-way distance traveled was 36.2 miles for Medicaid patients, 21.3 miles for Medicare patients, 24.1 miles for commercial/private insurance patients, and 25.3 miles for uninsured/private pay patients (P<.00). Subgroup analysis noted a statistical difference in distance traveled for the general orthopedics/adult reconstruction and sports/upper extremity groups. The study's findings suggest that having insurance does not equal access to outpatient orthopedic care at a single institution. The specific burdens that each group faces to gain access to care are unclear.
Subject(s)
Health Services Accessibility/statistics & numerical data , Insurance Coverage/statistics & numerical data , Orthopedics/statistics & numerical data , Adult , Humans , Retrospective StudiesABSTRACT
OBJECTIVES: Osmotically acting amino acids can be cytoprotective following injury. As threonine (THR) induces osmotic cell swelling, our aim was to investigate the potential for THR to induce cellular protection in intestinal epithelial cells and evaluate possible mechanisms of protection. METHODS: Cells treated with a range of THR doses were evaluated following heat stress (HS) injury. Alpha-aminoisobutyric acid (AIB), a non-metabolizable amino acid analog, was used as an osmotic control. MTS assays were used to assess cell survival. Heat shock protein (HSP) expression and cleaved caspase-3 (CC3) were evaluated via Western blot. Cell morphology and cell size were analyzed via microscopy. RESULT: Following HS, THR treatment increased cell viability in a dose dependent manner vs. non-THR treated cells (CT). The non-metabolized amino acid analogue, AIB, also increased cell survival in heat-stressed cells versus HS controls. HSP70 and HSP25 expression increased with THR and AIB treatment versus HS controls. THR also increased HSP25 in non-stressed cells. Microscopic evaluation revealed both THR and AIB preserved the structural integrity of the actin cytoskeleton in heat-stressed cells versus HS controls. THR, but not AIB, enhanced nuclear translocation of HSP25 during HS. This nuclear translocation was associated with a 60% decrease in apoptosis in heat-stressed cells with THR. No antiapoptotic effect was observed with AIB. CONCLUSIONS: This is the first demonstration that THR increases HSP70 and HSP 25 and protects cells from HS. THR's mechanism of protection may involve cytoskeletal stabilization, HSP up-regulation and nuclear translocation, and decreased apoptosis. THR's protection appears to involve both cell-swelling-dependent and -independent processes.