Journal of thermal biology最新文献

Magnetic fluid hyperthermia (MFH) offers a targeted means of thermally degrading malignant tissue by impregnating superparamagnetic nanoparticles (SPMNPs) within a tumor and exciting them with an alternating magnetic field. Although numerical modeling has been attempted before to guide MFH treatment optimization, systematic studies jointly integrating specific tissue categories, clinically realistic nanoparticle distributions, and dynamic perfusion evolution remain absent from the literature, leaving a critical gap in personalized MFH treatment planning. To address this, we develop a finite-element framework that integrates realistic SPMNPs distribution functions, along with a perfusion model whose magnitude varies with thermally induced tissue damage, all embedded within the Pennes bioheat formulation. Using representative breast compositions and tumor types, we investigate five spatial SPMNP-distributions under magnetic field conditions constrained by the magnetic field-frequency/Hergt-Dutz (Hf) threshold. The simulations resolve transient temperature fields, quantify thermal injury, and assess treatment quality across fatty to highly dense breast categories. The results indicate that fat-rich tumors exhibit a faster temperature rise than muscle-dominant tumors, and that the relative ease of heating mirrors the proportion of adipose to fibroglandular tissue in the surrounding breast. For deeply situated lesions, the extent of healthy-tissue injury is governed more strongly by the duration of heating than by the peak temperature attained, underscoring the importance of temporal control in MFH. Among the investigated spatial SPMNP-patterns, the radial Gaussian distribution consistently delivers the most advantageous balance - enhancing energy deposition within the tumor while restraining damage to adjacent tissue. These findings offer valuable insights for tailored, patient-specific hyperthermia therapy, thus lending to the successful clinical implementation of MFH as a promising tool for localized breast cancer treatment.

Climatological variations, triggered by global warming and rising temperatures, have become a growing concern, posing challenges to communities across the United States, Europe, and Asia. Earth heats, climate patterns shift, and the resulting climate instability triggers more persistent and powerful heatwaves, leading to significant ecological and health-related consequences. Disturbances in thermoregulation can lead to elevated core body temperature (CBT>39 °C); this typically occurs during heat stress (HS), a state wherein the body's capacity to cool itself is challenged by multiple external (environmental conditions, pathogens) or internal factors (inflammatory, metabolic, hormonal, and neurological), often precipitating systemic inflammation and multiple organ failure. HS pathological cascade involves different interconnected processes like oxidative stress, inflammation, compromised circulation, disrupted blood-brain barrier (BBB), coagulation irregularities, organ-specific responses, electrolyte imbalances, heat shock proteins (HSPs), and interactions with pre-existing conditions. To effectively address this emerging public health issue, a combined approach is needed, like incorporating pharmacological treatments such as non-steroidal anti-inflammatory drugs (NSAIDs), diuretics, muscle relaxants, vasodilators, beta-blockers, and anti-anxiety agents with essential non-pharmacological supports like public health education, cooling centres, early detection systems, and individualized plans specifically designed for high-risk groups. This review provides insight into the concept of heat-induced injury on the cellular level, the worldwide prevalence of HS, the pathogenic mechanisms behind Heat Stress-induced Multiple Organ Dysfunction (HS-MOD), and the various therapeutic strategies available.

To address uneven temperature distribution from vascular cooling in liver tumor magnetic hyperthermia, this study proposes a clinically oriented zonal control strategy using magnetic media with distinct Curie temperatures (66 °C and 75 °C). By constructing a Multiphysics coupled model of a liver tumor with a Y-shaped vascular structure, and validating the model's effectiveness through ex vivo tissue experiments, we simulated the temperature field distribution under alternating magnetic fields. Additionally, we analyzed the effects of blood flow velocity, vascular bifurcation angle, and vessel diameter on the surrounding tissue temperature. The results demonstrate that this strategy enables precise thermal ablation in the tumor core (up to 71.7 °C) while maintaining safe temperatures in perivascular regions (∼38.5 °C) and achieving effective hyperthermia at the tumor margin (43 °C). The study confirms that magnetic field intensity has a dominant influence over frequency in temperature elevation. This approach provides a theoretical and experimental basis for developing targeted and safe hyperthermia in highly vascularized tumors, overcoming the challenge of vascular heat dissipation.

Heat stress during summer poses a major challenge to reproductive efficiency in Murrah buffalo bulls by disrupting testicular thermoregulation and vascular perfusion, ultimately impairing semen quality. This study aimed to evaluate the relationships among testicular temperature gradient (TG), testicular blood flow, and semen parameters in twelve adult Murrah bulls maintained under summer stress (average THI 80.6). Infrared thermography (IRT) was performed fortnightly to measure scrotal surface temperatures at proximal and distal poles, and TG was calculated as the difference. Colour Doppler ultrasonography was used monthly to assess blood perfusion at the testicular vascular cone subjectively (vascularity score, 1-5) and objectively (percentage area of Doppler signal). Semen was collected using artificial vagina fortnightly and analyzed for volume, concentration, mass motility, progressive motility, viability, acrosome integrity, hypo-osmotic swelling test (HOST) response, and abnormality rate Bulls were stratified into two TG-based groups (>3 °C and <3 °C), with six animals in each group. Bulls with TG > 3 °C exhibited significantly higher testicular blood flow (52.7 ± 1.6% vs. 40.6 ± 2.1%) and vascularity scores (3.3 ± 0.1 vs. 2.5 ± 0.1). They also showed significant improvements in progressive motility (79.3 ± 1.6% vs. 71.1 ± 1.2%), viability (82.9 ± 0.9% vs. 76.4 ± 1.7%), acrosome integrity (86.6 ± 0.2% vs. 84.0 ± 0.3%), and HOST response (68.0 ± 0.7% vs. 63.0 ± 0.5%), along with significantly lower abnormal spermatozoa (10.8 ± 0.2% vs. 13.3 ± 0.3%). Correlation and regression analyses confirmed strong associations between TG, perfusion metrics, and semen traits, while elevated THI negatively influenced testicular function. IRT and Doppler assessments were a reliable and non-invasive biomarkers for detection of sperm quality impairment in heat-stressed Murrah bulls, with potential applications for efficient reproductive management to reduce the adverse effect of heat stress.

There is a growing interest in understanding the thermal tolerance of ectotherms across life stages. Identifying the stages that are most sensitive can help develop more robust projections on the consequences of climate impacts to populations, as well as help guide management and conservation efforts. Here, we estimate upper and lower thermal tolerance (as Critical Thermal maximum, CTmax, and minimum, CTmin) of Atlantic bluefin tuna (Thunnus thynnus) larvae. This species is an iconic apex predator that exhibits regional endothermy during the adult stage, but thermal tolerance of larvae was unknown. CTmin and CTmax were estimated in larvae grown from wild eggs under laboratory conditions. The mean (±SE) CTmax and CTmin across all tested batches and developmental stages was 31.7 (±0.6) and 17.9 (±0.7)°C, respectively. Rate of temperature change (1.5, 3, 6, or 9 °C h^-1) had no effect on the thermal tolerance estimates. Similarly, CTmin and CTmax were consistent across preflexion, flexion, and postflexion larval stages. The observed high inter-individual variability in CTmin and CTmax (11-13 °C) likely reflects methodological challenges related to the extreme sensitivity of the species to handling stress and confinement. Present and future thermal safety margin (by 2060) for larvae in the Balearic Islands are 3.6 (±0.6 SE) °C and 1.8 (±0.6 SE)°C, respectively. Future research should continue exploring alternative methods for estimating thermal limits and incorporate experimental designs with multiple stressors such as exposing well- and poorly-fed larvae to heatwaves and/or different light levels.