Hyperthermic Conditions Research Articles

Computational assessment of thermostability in miRNA:CNT system using molecular dynamics simulations

BackgroundCarbon nanotubes (CNTs) show great promise as theranostic agents due to their drug delivery properties, intrinsic near-infrared radiation-responsiveness, and magnetic functionalization. However, temperature elevation caused by these external stimuli during drug delivery should be considered for the evaluation of CNT-based systems loaded with temperature-sensitive biomolecules. MethodsWe examine the thermal stability of a 33 nucleotides long hairpin miRNA encapsulated in (20,20) CNT using all-atom molecular dynamics simulations in explicit water. We systematically increase the temperature as 298, 310, 327, and 343 K, reaching the melting temperature of miRNA. To emphasize the effect of the aromatic confined space, we compare the dynamics of miRNA inside the CNT to its dynamics free in the solution at the same temperatures, reaching a total simulation time of 7.9 μs. ResultsmiRNA hairpin mostly maintains its double-stranded structure in the confined CNT, even at elevated temperatures. Binding free energies and potential of mean force calculations also underline the strong π-π interactions between the biomolecule and the CNT for 298–343 K. ConclusionThe let-7 miRNA mimic, which represents a wide family of RNAi-based therapeutics, can be transported in the CNT under medically applied hyperthermic conditions. General significanceThis study shows how the structure and dynamics of miRNA hairpin are affected when encapsulated in an aromatic tube, during a systematic increase of temperature. It also indicates the high potential of CNT-based systems for the delivery of oligonucleotide therapeutics while simultaneous imaging/magnetic field guiding to the target tissue is achieved.

Immunogenicity of Externally Activated Nanoparticles for Cancer Therapy.

Simple SummaryRecent advances in treating cancer via stimulating an anti-tumor immune system response have resulted in extraordinary results for lymphomas and leukemias; however these therapies have not performed well in solid tumors. External beam therapies, such as radiotherapy, hyperthermia, and photodynamic therapy, that are clinically used for solid tumors are now being explored in combination with nanoparticle systems to stimulate a long-term anti-tumor immune system response. In this review, we detail the novel nanoparticle complexes that are being researched to activate an anti-tumor immune response in combination with external beam therapy in both the preclinical and clinical settings.Nanoparticles activated by external beams, such as ionizing radiation, laser light, or magnetic fields, have attracted significant research interest as a possible modality for treating solid tumors. From producing hyperthermic conditions to generating reactive oxygen species, a wide range of externally activated mechanisms have been explored for producing cytotoxicity within tumors with high spatiotemporal control. To further improve tumoricidal effects, recent trends in the literature have focused on stimulating the immune system through externally activated treatment strategies that result in immunogenic cell death. By releasing inflammatory compounds known to initiate an immune response, treatment methods can take advantage of immune system pathways for a durable and robust systemic anti-tumor response. In this review, we discuss recent advancements in radiosensitizing and hyperthermic nanoparticles that have been tuned for promoting immunogenic cell death. Our review covers both preclinical and clinical results, as well as an overview of possible future work.

Disrupted Anti-correlation Between the Default and Dorsal Attention Networks During Hyperthermia Exposure: An fMRI Study.

Environmental hyperthermia is a common risk factor for occupational safety in many situations due to decreased vigilance performances. Previously, we have reported that decreased resting-state functional connectivity within the default mode network (DMN) and decreased activations in dorsal attention network (DAN) such as dorsolateral prefrontal cortex (DLPFC) were correlated with selective attention deficits during hyperthermia. However, whether the inherent functionally organized anti-correlation between the DMN and DAN would contribute to the behavioral deficits remains unclear. In this study, we collected the resting-state fMRI data of 25 participants during two simulated thermal conditions: normothermic condition (25°C for 1 h) and hyperthermic condition (50°C for 1 h). Using group independent component analysis (ICA), we investigated the functional connectivity within the DMN and DAN, as well as the anti-correlations between both networks. Paired comparisons revealed that decreased intranetwork functional connectivity in the medial prefrontal cortex (mPFC)/anterior cingulate cortex (ACC) in the DMN contributed to executive control performance during hyperthermia using multivariate linear regression analysis. Paired comparison on the DAN showed that increased one in the posterior part of the middle and inferior temporal gyrus nearby the temporal–parietal junction area contributed to preserved alerting performance. Lastly but most importantly, we found that decreased correlation between mPFC in the DMN and intraparietal sulcus (IPS) area in the DAN contributed to the executive control deficit, suggesting a weaker intrinsic anti-correlation between DMN and DAN during hyperthermia. These findings indicated that a functional reorganized architecture of DMN and DAN might provide a potential neural basis of the selective deficits for different cognitive-demand attention tasks in high-temperature environments.

Paclitaxel increases sensitivity of SKOV3 cells to hyperthermia by inhibiting heat shock protein 27

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising treatment strategy for patients with peritoneal metastasis of ovarian cancer. Heat shock proteins (HSPs) play an important role in cellular stress during HIPEC treatment. The aim of the present study was to investigate whether paclitaxel can exert antitumor effects by inhibiting heat shock protein 27 (HSP27) expression during HIPEC treatment. Cell viability was detected by CCK8 assay. We used Western blot analysis to detect HSP27 expression under hyperthermia conditions with or without paclitaxel in SKOV3 cells. To further examine the role of HSP27 in the apoptosis, Bcl-2, Bax and Caspase-3 protein expression were additionally determined after reducing HSP27 levels using an siRNA strategy, and apoptosis was detected using the Annexin V/PI assay. The upregulation of HSP27 expression was accompanied with a rise in temperature. In addition, HSP27 could promote Bcl-2 expression, inhibit Bax and Caspase-3 expression, reduce the Bax / Bcl-2 ratio markedly in SKOV3 cells. Furthermore, paclitaxel could upregulate the Bax / Bcl-2 ratio by inhibiting HSP27 expression, and in turn, promoting apoptosis due to hyperthermia. Paclitaxel could also promote apoptosis by inhibiting HSP27 in SKOV3 cells. Our results demonstrate a synergistic effect between paclitaxel and hyperthermia at the cellular level.

Chemically Activated Cooling Vest's Effect on Cooling Rate Following Exercise-Induced Hyperthermia: A Randomized Counter-Balanced Crossover Study.

Background and objectives: Exertional heat stroke (EHS) is a potentially lethal, hyperthermic condition that warrants immediate cooling to optimize the patient outcome. The study aimed to examine if a portable cooling vest meets the established cooling criteria (0.15 °C·min−1 or greater) for EHS treatment. It was hypothesized that a cooling vest will not meet the established cooling criteria for EHS treatment. Materials and Methods: Fourteen recreationally active participants (mean ± SD; male, n = 8; age, 25 ± 4 years; body mass, 86.7 ± 10.5 kg; body fat, 16.5 ± 5.2%; body surface area, 2.06 ± 0.15 m2. female, n = 6; 22 ± 2 years; 61.3 ± 6.7 kg; 22.8 ± 4.4%; 1.66 ± 0.11 m2) exercised on a motorized treadmill in a hot climatic chamber (ambient temperature 39.8 ± 1.9 °C, relative humidity 37.4 ± 6.9%) until they reached rectal temperature (TRE) >39 °C (mean TRE, 39.59 0.38 °C). Following exercise, participants were cooled using either a cooling vest (VEST) or passive rest (PASS) in the climatic chamber until TRE reached 38.25 °C. Trials were assigned using randomized, counter-balanced crossover design. Results: There was a main effect of cooling modality type on cooling rates (F[1, 24] = 10.46, p < 0.01, η2p = 0.30), with a greater cooling rate observed in VEST (0.06 ± 0.02 °C·min−1) than PASS (0.04 ± 0.01 °C·min−1) (MD = 0.02, 95% CI = [0.01, 0.03]). There were also main effects of sex (F[1, 24] = 5.97, p = 0.02, η2p = 0.20) and cooling modality type (F[1, 24] = 4.38, p = 0.047, η2p = 0.15) on cooling duration, with a faster cooling time in female (26.9 min) than male participants (42.2 min) (MD = 15.3 min, 95% CI = [2.4, 28.2]) and faster cooling duration in VEST than PASS (MD = 13.1 min, 95% CI = [0.2, 26.0]). An increased body mass was associated with a decreased cooling rate in PASS (r = −0.580, p = 0.03); however, this association was not significant in vest (r = −0.252, p = 0.39). Conclusions: Although VEST exhibited a greater cooling capacity than PASS, VEST was far below an acceptable cooling rate for EHS treatment. VEST should not replace immediate whole-body cold-water immersion when EHS is suspected.

Sex difference in cerebral blood flow velocity during exercise hyperthermia.

Cerebral blood flow and thermal perception during physical exercise under hyperthermia conditions in females are poorly understood. Because sex differences exist for blood pressure control, resting middle cerebral artery velocity (MCAVmean), and pain, we tested the hypothesis that females would have greater reductions in MCAvmean and increased thermal perceptual strain during exercise hyperthermia compared to males. Twenty-two healthy active males and females completed 60min of matched exercise metabolic heat production in a 1) control cool (24.0±0.0°C; 14.4±3.4% Rh) and 2) hot (42.3±0.3°C; 28.4±5.2% Rh) conditions in random order, separated by at least 3 days while MCAvmean, thermal comfort, and preference was obtained during the exercise. Compared to 36°C mean body temperature (Mbt), as hyperthermia increased to 39°C Mbt, females had a greater reduction in absolute (MCAvmean), and relative change (%Δ MCAvmean) and conductance (%Δ MCAvmean conductance) in MCAVmean compared to males (Interaction: Temperature x Sex, P≤0.002). During exercise in cool conditions, absolute and conductance MCAvmean was maintained from rest through exercise; however, females had greater MCAVmean compared to males (Main effect: Sex, P<0.0008). We also found disparities in females' perceptual thermal comfort and thermal preference. These differences may be associated with a greater reduction in partial pressure of end-tidal CO2, and different cardiovascular and blood pressure control to exercise under hyperthermia. In summary, females exercise cerebral blood flow velocity is reduced to a greater extent (25% vs 15%) and the initial reduction occurs at lower hyperthermia mean body temperatures (~38°C vs ~39°C) and are under greater thermal perceptual strain compared to males.

Particle size-dependent magnetic hyperthermia in gadolinium silicide micro- and nano-particles from calorimetry and AC magnetometry

Self-regulating magnetic hyperthermia, in which heating of magnetic particles is limited by the magnetic transition temperature, could be a valuable form of magnetic hyperthermia for cancer treatment, as it can ensure uniform heating across tumor tissue. Gadolinium silicide has been suggested as a candidate material for self-regulating magnetic hyperthermia because of its high magnetization, Curie temperature near the desired treatment temperature, and tunability. Previous measurements of polydisperse micro- and nano-particles prepared from ball-milled Gd5Si4 yielded a decreased Curie temperature TC with a broad transition, suggesting that particle size may be used to tune TC. Other studies of size-selected particles of ball-milled Gd5Si4 showed decreased TC and magnetization with decreased particle size, but increased coercivity with decreased size, and the combined effects on the specific loss power were unknown. This work presents measurements of the particle size-dependence of the specific loss power of ball-milled Gd5Si4, showing that the largest particles (approx. 780 nm) behave similarly to the previously measured polydisperse samples, while the smaller particles all have decreased specific loss power. Dynamic hysteresis loop measurements show that the coercivity of the particles is increased under the conditions used for magnetic hyperthermia (particles dispersed in water, under an alternating magnetic field) relative to quasistatic measurements of powder samples, though a particle size-dependence of the coercivity was not observed under hyperthermia conditions. This work highlights one of the challenges of implementing self-regulating magnetic hyperthermia: in general, materials tend to have low coercivity near the magnetic transition temperature. Given this challenge, rare-earth compounds with high magnetization may provide the best opportunity to obtain significant heating for self-regulating hyperthermia.

Synthesis, Characterization and Magnetic Hyperthermia of Monodispersed Cobalt Ferrite Nanoparticles for Cancer Therapeutics.

Magnetic nanoparticles such as cobalt ferrite are investigated under clinical hyperthermia conditions for the treatment of cancer. Cobalt ferrite nanoparticles (CFNPs) synthesized by the thermal decomposition method, using nonionic surfactant Triton-X100, possess hydrophilic polyethylene oxide chains acting as reducing agents for the cobalt and iron precursors. The monodispersed nanoparticles were of 10 nm size, as confirmed by high-resolution transmission electron microscopy (HR-TEM). The X-ray diffraction patterns of CFNPs prove the existence of cubic spinel cobalt ferrites. Cs-corrected scanning transmission electron microscopy–high-angle annular dark-field imaging (STEM–HAADF) of CFNPs confirmed their multi-twinned crystallinity due to the presence of atomic columns and defects in the nanostructure. Magnetic measurements proved that the CFNPs possess reduced remnant magnetization (MR/MS) (0.86), which justifies cubic anisotropy in the system. Microwave-based hyperthermia studies performed at 2.45 GHz under clinical conditions in physiological saline increased the temperature of the CFNP samples due to the transformation of radiation energy to heat. The specific absorption rate of CFNPs in physiological saline was 68.28 W/g. Furthermore, when triple-negative breast cancer cells (TNBC) in the presence of increasing CFNP concentration (5 mg/mL to 40 mg/mL) were exposed to microwaves, the cell cytotoxicity was enhanced compared to CFNPs alone.

Valproic Acid Thermally Destabilizes and Inhibits SpyCas9 Activity

The clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 system plays an important role in prokaryotic adaptive immunity. Due to its capacity for sequence-specific gene editing, CRISPR-Cas9 has become one of the most important tools widely used for genome editing in molecular biotechnology. However, its clinical application is currently limited by unwanted mutations at off-target sites. Various strategies have been developed for precise control of Cas9 in order to reduce these off-target effects, including chemical-based approaches. From a chemical screening, I observed that valproic acid (VPA) binds to and destabilizes Streptococcus pyogenes Cas9 (SpyCas9) protein invitro, as well as in cells, while within its therapeutical concentration range under conditions of hyperthermia as demonstrated. Conditions were generated either by an external heat bag or in combination with the photothermal therapeutic agent indocyanine green activated by a near-infrared laser. Use of other histone deacetylase inhibitors failed, suggesting a histone deacetylase inhibition-independent function of VPA. Thus, this finding provides an uncomplicated thermotherapeutical approach for timely regulation of the activity of the CRISPR-Cas9 system at desired locations.

Abstract 1451: Hyperthermic conditions improve curcumin efficacy for the treatment of peritoneal carcinomatosis of colon cancer origin

Abstract Patients with peritoneal metastases from colorectal cancer (CRC) have poor prognosis. Systemic chemotherapy by itself is often ineffective in the treatment of peritoneal carcinomatosis. Cytoreductive surgery (CRS) with heated intraperitoneal chemotherapy (HIPEC) is offered to appropriately selected patients. HIPEC consists of direct application of high-dose chemotherapy to the peritoneal cavity under hyperthermic conditions for 90-120 minutes. Although there is strong evidence to demonstrate improved survival with cytoreductive surgery, the role of HIPEC needs further evaluation. Furthermore, despite optimal cytoreduction, a subset of patients will suffer early peritoneal recurrence which indicates that the intraperitoneal chemotherapy was ineffective in controlling the microscopic disease. In vitro studies focused on optimizing the drug, duration of exposure, and temperature based on the biology of the cancer are critically needed to inform the design of future clinical trials. The combination of the HIPEC treatment modality with curcumin as the therapeutic agent is attractive since the naturally occurring curcumin has fewer side effects than drugs currently used for HIPEC. Additionally, although curcumin possesses antitumor effects on various cancers including colon, its efficacy is hindered by a low systemic bioavailability. For HIPEC, curcumin could be delivered directly into the peritoneal cavity, thereby increasing bioavailability. We hypothesize that curcumin used alone or in combination with standard regimen mitomycin C treatment in HIPEC will exert antitumor effects superior to the standard regimen HIPEC. To assess this hypothesis, we developed an in vitro model in which colon cancer cell lines (SK-CO-1, COLO205 and SNU-C1) were treated with curcumin (25 µM) or mitomycin C (1 µM) alone or in combination at different exposure times (1, 2 or 3 hours), and then incubated at either 37°C (normothermia) or 42 °C (hyperthermia), simulating conditions used in clinical practice. Cell lines were chosen in order to determine the effects of p53 (SNU-C1 &amp; COLO205), KRAS (SK-CO-1) and BRAF (COLO205) mutation status on this proposed intraperitoneal chemotherapy strategy. After treatment, cells were maintained at 37°C for 24, 48, and 72 hours after which cell viability was assessed using Annexin V/PI, trypan blue and Hoffman microscopy. Our results indicate that hyperthermia enhances the efficacy of curcumin treatment as evidenced by a significant two-fold decrease in cell viability compared to normothermia in vitro in all three cell lines. No mutation-associated effect was quantified. Though additional comparisons are still forthcoming, the addition of curcumin to HIPEC may be a promising novel therapeutic option. Citation Format: Janviere Kabagwira, Paul A. Vallejos, Audrey H. Choi, Chase Sugiono, Vola-Masoandro Andrianarijaona, Jazmine Chism, William HR Langridge, Maheswari Senthil, Nathan R. Wall. Hyperthermic conditions improve curcumin efficacy for the treatment of peritoneal carcinomatosis of colon cancer origin [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1451.

Algorithmically Controlled Electroporation: A Technique for Closed Loop Temperature Regulated Pulsed Electric Field Cancer Ablation.

To evaluate the effect of a closed-loop temperature based feedback algorithm on ablative outcomes for pulsed electric field treatments. A 3D tumor model of glioblastoma was used to assess the impact of 2μs duration bipolar waveforms on viability following exposure to open and closed-loop protocols. Closed-loop treatments evaluated transient temperature increases of 5, 10, 15, or 22°C above baseline. The temperature controlled ablation diameters were conditionally different than the open-loop treatments and closed-loop treatments generally produced smaller ablations. Closed-loop control enabled the investigation of treatments with steady state 42°C hyperthermic conditions which were not feasible without active feedback. Baseline closed-loop treatments at 20°C resulted in ablations measuring 9.9 ± 0.3mm in diameter while 37°C treatments were 20% larger (p < 0.0001) measuring 11.8 ± 0.3mm indicating that this protocol induces a thermally mediated biological response. A closed-loop control algorithm which modulated the delay between successive pulse waveforms to achieve stable target temperatures was demonstrated. Algorithmic control enabled the evaluation of specific treatment parameters at physiological temperatures not possible with open-loop systems due to excessive Joule heating. Irreversible electroporation is generally considered to be a non-thermal ablation modality and temperature monitoring is not part of the standard clinical practice. The results of this study indicate ablative outcomes due to exposure to pulses on the order of one microsecond may be thermally mediated and dependent on local tissue temperatures. The results of this study set the foundation for experiments in vivo utilizing temperature control algorithms.

Litopenaeus vannamei oxygen consumption and HSP gene expression at cyclic conditions of hyperthermia and hypoxia

Although Litopenaeus vannamei is a widely studied species, the information on how the organisms respond to natural daily variations of environmental conditions such as temperature and dissolved oxygen, and how such conditions alter the physiological responses, is scarce. In the present work, the strategies used by shrimps to cope with temperature and dissolved oxygen fluctuations during 24 days were investigated through the evaluation of oxygen consumption and heat shock proteins (HSP) gene expression. During daily fluctuations, no change in oxygen consumption in the short-term, but a significant increase in the long-term during hyperthermia conditions was registered, whereas a significant decrease during hypoxia was observed during all the bioassay. On the other hand, HSP70 and HSP90 gene expression increased in gills under thermal stress but was down-regulated under hypoxia, in both the short- and the long-term. This study highlights that to counteract environmental variations of temperature and dissolved oxygen, the shrimps use molecular compensatory mechanisms (HSP gene expression) that are different to those used under constant hypoxic conditions, suggesting that hypoxia can compromise physiological cytoprotection.

Transcriptomic and Proteomic Analysis of Mannitol-metabolism-associated Genes in Saccharina japonica

As a carbon-storage compound and osmoprotectant in brown algae, mannitol is synthesized and then accumulated at high levels in Saccharina japonica (Sja); however, the underlying control mechanisms have not been studied. Our analysis of genomic and transcriptomic data from Sja shows that mannitol metabolism is a cyclic pathway composed of four distinct steps. A mannitol-1-phosphate dehydrogenase (M1PDH2) and two mannitol-1-phosphatases (M1Pase1 and MIPase2) work together or in combination to exhibit full enzymatic properties. Based on comprehensive transcriptomic data from different tissues, generations, and sexes as well as under different stress conditions, coupled with droplet digital PCR (ddPCR) and proteomic confirmation, we suggest that SjaM1Pase1 plays a major role in mannitol biosynthesis and that the basic mannitol anabolism and the carbohydrate pool dynamics are responsible for carbon storage and anti-stress mechanism. Our proteomic data indicate that mannitol metabolism remains constant during diurnal cycle in Sja. In addition, we discover that mannitol-metabolism-associated (MMA) genes show differential expression between the multicellular filamentous (gametophyte) and large parenchymal thallus (sporophyte) generations and respond differentially to environmental stresses, such as hyposaline and hyperthermia conditions. Our results indicate that the ecophysiological significance of such differentially expressed genes may be attributable to the evolution of heteromorphic generations (filamentous and thallus) and environmental adaptation of Laminariales.

The effectiveness of the Madufor® feed additive in hyperthermia conditions for broiler chickens

Among the severe lightning-fast pathological processes that affect farm animals and poultry of all age categories, it is worthwhile to highlight overheating and dehydration, which are especially common in the southern regions of the country. The paper presents the results of studies on the effectiveness of Madufor® feed additives in heat stress of broiler chickens. According to the results of hematological studies, it was found that the content of red blood cells, hemoglobin, hematocrit and platelets in the blood of chickens of the control group was at the upper boundary of the physiological norm or slightly exceeded them. Thus, the level of red blood cells in the control group was 4.18·1012/l, hemoglobin 107.11g/l, hematocrit 39.32% and platelets 232.85·109/l, and in the experimental group these indicators were within the physiological norm and amounted to 3.47·1012/l, 103.89g/l, 34.48% and 168.85·109/l, respectively, which indicates the normalization of metabolic processes in the body of broiler chickens under the influence of the Madufor® feed additive. In the blood serum of broiler chickens in the control group, an increased total protein content of 5.28g/l (11.91%; P<0.01) was compared with the experimental group. The AST level in the control group also exceeded the similar values of the experimental group by 15.06 units/l at P<0.01. During the experiment, the mineral composition of the blood serum of the chickens of the experimental group improved in relation to the control. The concentration of calcium, sodium and potassium significantly exceeded the control by 14.78 (P<0.05), 1.65 (P<0.05) and 8.15% (P<0.01), and the level of phosphorus tended to increase with an unreliable difference. Throughout the cultivation, the live weight of the chickens of the experimental group exceeded the control values. During the finishing fattening of broilers of the experimental group at the age of 28 and 35 days, their live weight exceeded the same indicator in the control group by 171.7 (13.06%; P<0.001) and 288.2 g (15.42%; P<0.001 ) Accordingly, feed consumption per 1 kg of growth in the control group was significantly higher than in the experimental group by 0.26 kg.

Thermally Targeted p50 Peptide Inhibits Proliferation and Induces Apoptosis of Breast Cancer Cell Lines.

The application of rationally designed therapeutic peptides (TP) may improve outcomes in cancer treatment. These peptides hold the potential to directly target proliferative pathways and stimulate cell arrest or death pathways. Elastin-like polypeptide (ELP) is an elastin derived biopolymer that undergoes a thermally mediated phase transition. This study employs p50, a nuclear localization sequence derived peptide that inhibits the activation of NFκB and is implicated in cancer cell survival and metastasis. In order to effectively delivery p50, it is conjugated to SynB1-ELP1, a thermally responsive macromolecular carrier. By applying an external heat source, mild hyperthermic conditions (41 °C) induce aggregation and therefore can be used to specifically target ELP to solid tumors in cancer therapy. The addition of a cell penetrating peptide (CPP) to the N-terminus of the macromolecular carrier enhances the cellular uptake and directs the subcellular localization of the bioactive peptide. The novel TP, p50, inhibits proliferation and induces apoptosis of breast cancer cells by blocking the intranuclear import of NFκB. By expanding the repertoire of oncogenic targets, CPPs, and ELP carrier sizes, ELP-based polypeptides may be modulated to optimize the delivery of these novel therapies and allow for the flexibility to create individualized cancer therapies.

The Temperature-Dependent Effectiveness of Platinum-Based Drugs Mitomycin-C and 5-FU during Hyperthermic Intraperitoneal Chemotherapy (HIPEC) in Colorectal Cancer Cell Lines.

Cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment with curative intent for peritoneal metastasis of colorectal cancer (CRC). Currently, there is no standardized HIPEC protocol: choice of drug, perfusate temperature, and duration of treatment vary per institute. We investigated the temperature-dependent effectiveness of drugs often used in HIPEC. Methods: The effect of temperature on drug uptake, DNA damage, apoptosis, cell cycle distribution, and cell growth were assessed using the temperature-dependent IC50 and Thermal Enhancement Ratio (TER) values of the chemotherapeutic drugs cisplatin, oxaliplatin, carboplatin, mitomycin-C (MMC), and 5-fluorouracil (5-FU) on 2D and 3D CRC cell cultures at clinically relevant hyperthermic conditions (38–43 °C/60 min). Results: Hyperthermia alone decreased cell viability and clonogenicity of all cell lines. Treatment with platinum-based drugs and MMC resulted in G2-arrest. Platinum-based drugs display a temperature-dependent synergy with heat, with increased drug uptake, DNA damage, and apoptosis at elevated temperatures. Apoptotic levels increased after treatment with MMC or 5-FU, without a synergy with heat. Conclusion: Our in vitro results demonstrate that a 60-min exposure of platinum-based drugs and MMC are effective in treating 2D and 3D CRC cell cultures, where platinum-based drugs require hyperthermia (>41 °C) to augment effectivity, suggesting that they are, in principle, suitable for HIPEC.

Interactions between Cisplatin and Quercetin at Physiological and Hyperthermic Conditions on Cancer Cells In Vitro and In Vivo.

Quercetin (QU), a hyperthermic sensitizer, when combined with cisplatin (CP) affects tumor growth. To determine the effects of QU and CP and their interactions, multimodal treatment in vitro and in vivo models under physiological and hyperthermic conditions was performed. In vitro, different sensitivity of T24 and UMUC human bladder cancer cells was observed after short-term exposure to QU (2 h) and CP (1 h). Effects of both compounds were investigated at low and high micromolar concentrations (1 and 50 µM, respectively) under both thermal conditions. QU acted in additive or synergistic manner in combination with CP between physiological condition and hyperthermia. As determined by 3-(4,5-dimethylthiazol2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, short-term application of QU and CP reduced cell viability. Clonal assay also indicated that combined treatment with QU and CP is lethal to bladder cancer cells in both conditions. In vivo, CP (5 or 10 mg kg−1) and QU (50 mg kg−1) acted synergistically with hyperthermia (43 °C) and inhibited tumor growth, activated immune effectors and increased mice survival. Our results demonstrate that combined treatment with CP and QU may increase death of tumor cells in physiological and hyperthermic conditions which could be clinically relevant in locoregional chemotherapy.

Sex Difference In Cerebral Blood Flow During Exercise Hyperthermia

PURPOSE: Young healthy females are more prevalent to orthostatic hypotension compared to males. It is unknown if females show similar cerebral blood flow hemodynamics (middle cerebral artery, MCAvmean) compared to males during exercise hyperthermia. We tested the hypothesis that females have an attenuated MCAvmean response to exercising in hyperthermic conditions. METHODS: Twenty-two healthy active adults (7 day activity: 8620±3008 steps/day; VO2max: 49±10 mL/kg/min ) adults (11M/11F, 22.4±4.9y, 169±7.6cm, 68.3±13kg) exercised at similar metabolic heat production (M: 7.1±1.5 W/kg and F: 6.9±1.4 W/kg; P=0.32) for 60 min (cycle ergometer) in cool (24.0±0.00C; 14.4±3.6%Rh) and hot (42.3±0.20C; 27.9±5.5%Rh) conditions in random order with 7 days washout. MCAvmean absolute and percent change from rest, MCAvmean conductance (MCAvmeanCVC), cardiac output index (COi) and systemic vascular resistance index (SVRi), and the difference between conditions (hot minus cool) were examined by a mixed model 2-way repeated-measures analysis of variance for Interaction (I) and Main Effect (ME) for time and sex. Significance was set at P<0.05. RESULTS: Thermal (ΔTin, Cool: Δ0.5±0.10C, Hot: Δ1.5±0.60C; ME: condition; P<0.0001) and cardiovascular strain (ΔHR Cool: 58±15 b/min, Hot: 71±15 b/min; ME: condition; P<0.01) were similar between sex and increased in hot compared to cool condition. During the cool condition, absolute MCAvmean and MCAvmeanCVC were higher in females compared to males (ME: sex P<0.005). In contrast, MCAvmean and MCAvmeanCVC increased then decreased over time in hot compared to the cool condition (ME: time; P<0.0001). COi increased in hot compared to cool condition (ME: condition; P<0.008). Females had greater SVRi compared to males in both conditions (ME: sex; P<0.008). However, the %change and the difference between conditions, females compared to males had an attenuated MCAvmean (ME: sex; P<0.03) and MCAvmeanCVC (I: time × sex; P<0.01). CONCLUSIONS: These data indicate that sex differences exist for exercise cerebral blood flow. Females have higher MCAvmean in cool and have an attenuated MCAvmean response during exercise hyperthermia compared to males. This sex difference may be due to differences in blood pressure and systemic vascular resistance.

Функциональное состояние плазмалеммы и апопласта в мезофилле ячменя в условиях гипертермии и инфицирования Bipolaris sorokiniana

Функциональное состояние плазмалеммы и апопласта в мезофилле ячменя в условиях гипертермии и инфицирования Bipolaris sorokiniana

The hyperthermophilic partners Nanoarchaeum and Ignicoccus stabilize their tRNA T-loops via different but structurally equivalent modifications.

The universal L-shaped tertiary structure of tRNAs is maintained with the help of nucleotide modifications within the D- and T-loops, and these modifications are most extensive within hyperthermophilic species. The obligate-commensal Nanoarchaeum equitans and its phylogenetically-distinct host Ignicoccus hospitalis grow physically coupled under identical hyperthermic conditions. We report here two fundamentally different routes by which these archaea modify the key conserved nucleotide U54 within their tRNA T-loops. In N. equitans, this nucleotide is methylated by the S-adenosylmethionine-dependent enzyme NEQ053 to form m5U54, and a recombinant version of this enzyme maintains specificity for U54 in Escherichia coli. In N. equitans, m5U54 is subsequently thiolated to form m5s2U54. In contrast, I. hospitalis isomerizes U54 to pseudouridine prior to methylating its N1-position and thiolating the O4-position of the nucleobase to form the previously uncharacterized nucleotide m1s4Ψ. The methyl and thiol groups in m1s4Ψ and m5s2U are presented within the T-loop in a spatially identical manner that stabilizes the 3′-endo-anti conformation of nucleotide-54, facilitating stacking onto adjacent nucleotides and reverse-Hoogsteen pairing with nucleotide m1A58. Thus, two distinct structurally-equivalent solutions have evolved independently and convergently to maintain the tertiary fold of tRNAs under extreme hyperthermic conditions.