Cryoablation used in fertility-sparing treatment for early endometrial cancer: A pig model experiment using a new designed balloon cryoprobe

Young patients with early endometrial cancer have a strong desire to retain reproductive function, which require us to develop a therapeutic method that can not only assure the complete resection of tumor but also retain the uterine integrity. In the present study, we proposed a fertility-sparing surgery option that combined hysteroscopic resection with cryoablation to achieve this goal. To verify the safety and effectiveness of cryoablation for local uterine wall, we designed the experiment in pig model using a novel cryoablation balloon probe. In the process of freezing and thawing, the temperature of different parts of the uterus was measured in real time. The uterus was harvested immediately, three weeks after cryotherapy for histological evaluation. The results demonstrated cryoablation using the new cryoprobe is safe and effective. The effective freezing range can cover a range of 2 cm in diameter at least. This study provided us evidence before cryoablation could be applied in clinical practice of fertility-sparing treatment for young women with early endometrial cancer.     

Validation of a new whole-body cryotherapy chamber based on forced convection

Whole-body cryotherapy (WBC) and partial-body cryotherapy (PBC) are two methods of cold exposure (from −110 to −195 °C according to the manufacturers). However, temperature measurement in the cold chamber during a PBC exposure revealed temperatures ranging from −25 to −50 °C next to the skin of the subjects (using isolating layer placed between the sensor and the skin). This discrepancy is due to the human body heat transfer. Moreover, on the surface of the body, an air layer called the boundary layer is created during the exposure and limits heat transfer from the body to the cabin air. Incorporating forced convection in a chamber with a participant inside could reduce this boundary layer. The aim of this study was to explore the use of a new WBC technology based on forced convection (frontal unilateral wind) through the measurement of skin temperature. Fifteen individuals performed a 3-min WBC exposure at −40 °C with an average wind speed of 2.3 m s⁻¹. The subjects wore a headband, a surgical mask, underwear, gloves and slippers. The skin temperature of the participants was measured with a thermal camera just before exposure, just after exposure and at 1, 3, 5, 10, 15 and 20 min after exposure. Mean skin temperature significantly dropped by 11 °C just after exposure (p<0.001) and then significantly increased during the 20-min post exposure period (p<0.001). No critically low skin temperature was observed at the end of the cold exposure. This decrease was greater than the mean decreases in all the cryosauna devices with reported exposures between −140 °C and −160 °C and those in two other WBC devices with reported exposures between −60 °C and −110 °C. The use of this new technology provides the ability to reach decreases in skin temperature similar to other technologies. The new chamber is suitable and relevant for use as a WBC device.     

Individualising the exposure of −110 °C whole body cryotherapy: The effects of sex and body composition

The purpose of this study was to investigate the effects of whole body cryotherapy (WBC) on a range of thermoregulatory measures. We also sought to examine the influence of sex and body composition. A convenience sample of 18 healthy participants (10 males and 8 females) (27±6 yr) volunteered for this study. Temperature (core, tympanic, skin and mean body), heart rate, blood pressure, and thermal comfort and sensation were recorded pre- and post- (immediately and every 5 min until 35 min post) exposure to a single bout of WBC (30 s at −60 °C, 150 s at 110 °C). Anthropometric data (height, weight, body surface area, body mass index, fat mass and fat free mass) were also recorded. No significant differences in temperature (core, tympanic, skin and mean body), heart rate, blood pressure, or thermal comfort / sensation were observed between male and females at baseline. Immediately post WBC mean body (male:31.9±0.8 °C; female:31.0±0.9 °C; ∆ mean body temperature:0.9±0.1 °C; P≤0.05, d=0.64) and mean skin (male:22.1±2.2 °C; female:19.6±2.8 °C; ∆ mean skin temperature:−2.5±0.6 °C; d=0.99, P≤0.05) temperature was significantly different between sexes. Sex differences were also observed in regional skin temperature (male thigh, 20.8±1.1 °C; female thigh, 16.7±1.1 °C, ∆ mean thigh skin temperature:−4.1 °C; d=3.72; male calf, 20.5±1.1 °C; female calf, 18.2±1 °C, ∆ mean calf skin temperature:−2.3±0.1 °C; d=3.61; male arm, 21.7±1 °C; female arm, 19±0.4 °C, ∆ mean arm skin temperature: −2.7±0.3 °C; d=3.54; P≤0.05). Mean arterial pressure was significantly different over time (P≤0.001) and between sexes (male 0 mins:94±10 mmHg; female 0 mins:85±7 mmHg; male 35 mins:88±7 mmHg; female 35 mins:80±6 mmHg; P≤0.05). Combined data set indicated a strong negative relationship between skin temperature and body fat percentage 35 min’ post WBC (r=−0.749, P≤0.001) and for core temperature and body mass index in males only (r=0.726, P≤0.05) immediately after WBC. There were no significant differences between sexes in any other variables (heart rate, tympanic and perceptual variables). We observed sex differences in mean skin and mean body temperature following exposure to whole body cryotherapy. In an attempt to optimise treatment, these differences should be taken into account if whole body cryotherapy is prescribed.     

High subzero cryofixation: A technique for observing ice within tissues

While various fixation techniques for observing ice within tissues stored at high sub-zero temperatures currently exist, these techniques require either different fixative solution compositions when assessing different storage temperatures or alteration of the sample temperature to enable alcohol-water substitution. Therefore, high-subzero cryofixation (HSC), was developed to facilitate fixation at any temperature above −80 °C without sample temperature alteration. Rat liver sections (1 cm²) were frozen at a rate of −1 °C/min to −20 °C, stored for 1 h at −20 °C, and processed using classical freeze-substitution (FS) or HSC. FS samples were plunged in liquid nitrogen and held for 1 h before transfer to −80 °C methanol. After 1, 3, or 5 days of −80 °C storage, samples were placed in 3% glutaraldehyde on dry ice and allowed to sublimate. HSC samples were stored in HSC fixative at −20 °C for 1, 3, or 5 days prior to transfer to 4 °C. Tissue sections were paraffin embedded, sliced, and stained prior to quantification of ice size. HSC fixative permeation was linear with time and could be mathematically modelled to determine duration of fixation required for a given tissue depth. Ice grain size within the inner regions of 5 d samples was consistent between HSC and FS processing (p = 0.76); however, FS processing resulted in greater ice grains in the outer region of tissue. This differed significantly from HSC outer regions (p = 0.016) and FS inner regions (p = 0.038). No difference in ice size was observed between HSC inner and outer regions (p = 0.42). This work demonstrates that HSC can be utilized to observe ice formed within liver tissue stored at −20 °C. Unlike isothermal freeze fixation and freeze substitution alternatives, the low melting point of the HSC fixative enables its use at a variety of temperatures without alteration of sample temperature or fixative composition.     

Effect of initial freezing temperature on the semen characteristics of frozen-thawed ram spermatozoa in a semi-arid tropical environment

Ram spermatozoa are sensitive to extreme changes in temperature during the freeze-thaw process. The degree of damage depends on a combined effect of various factors including initial freezing temperature. The present study was conducted to observe the effect of initial freezing temperature on post-thawing motility of ram spermatozoa of native and crossbred rams maintained in a semi-arid tropical environment. Good quality semen obtained from native Malpura and crossbred Bharat Merino rams were pooled within breed and diluted at a rate of 1000 million spermatozoa per milliliter in TEST—yolk–glycerol extender. Diluted semen samples were loaded in 0.25 ml straws and cooled to −25, −75 or −125 °C freezing temperature at the rate of −25 °C/min under controlled conditions before plunging into liquid nitrogen for storage. The thawing of straws was performed at 50 °C in a water bath for 10 s and motility characteristics of the frozen-thawed spermatozoa were assessed by a computer-assisted spermatozoa analysis technique. Initial freezing temperature significantly affected the post-thawing motility of sperm in both the breeds. The post-thawing % motility and rapid motile spermatozoa were significantly higher at initial freezing temperature of −125 °C and lower at −25 or −75 °C. The percentage medium motile sperm were similar at all three initial freezing temperatures. The percentage of slow motile and linearity of sperm varied (P<0.01) between the different freezing temperatures. The curvilinear velocity, average path velocity and straight line velocity of spermatozoa were higher (P<0.01) at −125 °C than −25 or −75 °C. Although the lateral head displacement of spermatozoa did not vary significantly between the different initial freezing temperatures, the stroke frequency was significantly lower at −25 °C than −75 or −125 °C. Except for % linearity, the average path velocity and straight line velocity, other spermatozoa characteristics were not significantly different between breeds. The interaction between freezing temperature and breed was significant only for the % motility and linearity of the spermatozoa. The study indicates that initial freezing temperature has a significant effect on spermatozoa motility and velocity following post-thawing. The best motile spermatozoa following thawing were achieved at −125 °C freezing temperature.     

Two-step accelerating freezing protocol yields a better motility,membranes and DNA integrities of thawed ram sperm than three-steps freezing protocols

The present study compares a protocol that mimics freezing of ram semen in static nitrogen vapor with two protocols with an initial low cooling rate in the first step, followed by higher cooling rates where ice nucleation occurs. Semen ejaculates, obtained from twelve adults rams, were diluted with TEST-based extender and frozen with either Protocol 1 (three-step decelerating cooling): from +5 °C to −35 °C (40 °C/min), from −35 °C to −65 °C (17 °C/min), and then from −65 °C to −85 °C (3 °C/min); or Protocol 2 (three-step accelerating cooling): from +5 °C to −5 °C (4 °C/min), from −5 °C to −110 °C (25 °C/min), and then from −110 °C to −140 °C (35 °C/min); or Protocol 3 (two-step accelerating cooling), from +5 °C to −10 °C (5 °C/min), and then from −10 °C to −130 °C (60 °C/min). Post-thaw sperm quality was reduced for all protocols (p < .05) compared with fresh semen. Post-thaw percentages of sperm motility characteristics and sperm with intact plasma membrane, intact acrosome, and intact mitochondrial membrane were greater using Protocol 3 than Protocol 2 (p < .05) and Protocol 1 (p < .01). In addition, the post-thaw percentage of sperm with fragmented DNA was lower (p < .05) using Protocol 3 compared with Protocol 1. The present results indicate that a cooling rate of 60 °C/min around and after the time point of ice nucleation provided better post thaw survival and function of ram sperm than lower (and/or decelerating) cooling rates.     

Modeling analysis on sporulation capacity,storage and infectivity of the aphid-specific pathogen Conidiobolus obscurus (Entomophthoromycota: Entomophthorales)

Entomophthorales are important natural enemies against agroforestry pests. Conidiobolus obscurus in this order, a common obligate aphid pathogen, possesses features of rapid growth in vitro and ease to mass production. This study sought to evaluate the potential of C. obscurus in aphid biocontrol, by modeling analyzing on the sporulation capacity and storage of its alginate formulation and infectivity to Myzus persicae. The C. obscurus mycelia-entrapping alginate pellets discharges 0.12–18.26 × 10⁴ conidia per pellet at 4−32 °C. The optimal temperature for the fungal sporulation was computed as 23.3 °C. Each pellet could sporulated for 7 d, releasing 22.3-fold more conidia than a cadaver at 24 °C. Moreover, it had longevity of 8 mo at 4 °C, with half decline time of 2.3 mo. The infectivity of C. obscurus was assessed by multi-concentration bioassays at 10−28 °C and 8−16 h light per d. The median lethal concentration (LC₅₀) at each temperature-photoperiod regime was computed based on the morality-concentration trend. The LC₅₀ values reached the lowest one of 15 conidia per mm² at 28 °C and 16:8 L:D cycles. The total results suggest that C. obscurus mycelia-inclusive alginate pellets meet the requirement of aphid biocontrol in the high-temperature surroundings of 24–28 °C.     

Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates

The extreme polar environment creates challenges for its resident invertebrate communities and the stress tolerance of some of these animals has been examined over many years. However, although it is well appreciated that standard air temperature records often fail to describe accurately conditions experienced at microhabitat level, few studies have explicitly set out to link field conditions experienced by natural multispecies communities with the more detailed laboratory ecophysiological studies of a small number of ‘representative’ species. This is particularly the case during winter, when snow cover may insulate terrestrial habitats from extreme air temperature fluctuations. Further, climate projections suggest large changes in precipitation will occur in the polar regions, with the greatest changes expected during the winter period and, hence, implications for the insulation of overwintering microhabitats. To assess survival of natural High Arctic soil invertebrate communities contained in soil and vegetation cores to natural winter temperature variations, the overwintering temperatures they experienced were manipulated by deploying cores in locations with varying snow accumulation: No Snow, Shallow Snow (30 cm) and Deep Snow (120 cm). Air temperatures during the winter period fluctuated frequently between +3 and −24 °C, and the No Snow soil temperatures reflected this variation closely, with the extreme minimum being slightly lower. Under 30 cm of snow, soil temperatures varied less and did not decrease below −12 °C. Those under deep snow were even more stable and did not decline below −2 °C. Despite these striking differences in winter thermal regimes, there were no clear differences in survival of the invertebrate fauna between treatments, including oribatid, prostigmatid and mesostigmatid mites, Araneae, Collembola, Nematocera larvae or Coleoptera. This indicates widespread tolerance, previously undocumented for the Araneae, Nematocera or Coleoptera, of both direct exposure to at least −24 °C and the rapid and large temperature fluctuations. These results suggest that the studied polar soil invertebrate community may be robust to at least one important predicted consequence of projected climate change.     

Cryopreservation of Bangladeshi ram semen using different diluents and manual freezing techniques

A study was conducted to establish a sustainable and effective manual freezing technique for cryopreservation of Bangladeshi ram semen. Three diluents and freezing techniques were tested, both as treatment combinations (diluent × freezing technique) and fixed effects (diluent or freezing technique) on post-thaw sperm motility (SM), viability (SV), plasma membrane integrity (SPMI) and acrosome integrity (SAI). Ten rams were selected, based on semen evaluation. Eight ejaculates were used for each treatment combination. Semen samples were diluted using a two-step protocol for home-made Tris-based egg yolk (20%, v/v) diluents: D1 (7% glycerol, v/v) and D2 (5% glycerol, v/v), and one-step for commercial diluent: D3 (Triladyl^®, consists of bi-distilled water, glycerol, tris, citric acid, fructose, spectinomycin, lincomycin, tylosin and gentamycin) at 35 °C. Fraction-A (without glycerol) was added at 35 °C, and following cooling of sample to 5 °C (−0.30 °C/min), Fraction-B (with glycerol) was added. The diluted semen samples were aspirated into 0.25 ml French straws, sealed, and equilibrated at 5 °C for 2 h. The straws were frozen in liquid nitrogen (LN) vapour, in a Styrofoam box. The freezing techniques were; One-step (F1): at −15.26 °C/min from +5 °C to −140 °C; Two-step (F2): at −11.33 °C/min from +5 °C to −80 °C, and −30 °C/min from −80 °C-140 °C; and Three-step (F3): at −11.33 °C/min from +5 °C to −80 °C, at −26.66 °C/min from to −80 °C to −120 °C, and at −13.33 °C/min from −120 °C to −140 °C. Two semen straws from each batch were evaluated before and after freezing. The group F3D3 exhibited significantly higher (p < 0.05) post-thaw SM 63.1 ± 2.5%, SV 79.0 ± 2.1% and SPMI 72.9 ± 1.7%, whereas SAI 72.9 ± 1.7% was significantly higher (p < 0.05) in group F3D2. The freezing technique F2 and F3 had significantly higher (p < 0.05) post-thaw sperm values compared to F1. The post-thaw SM and SV were above 50% and 65% with the freezing technique F2 and F3 but differed non-significant. The SPMI 67.6 ± 2.0% and SAI 76.1 ± 1.4% were significantly higher (p < 0.05) with F3. Likewise, the diluent D2 and D3 had significantly higher (p < 0.05) post-thaw sperm values compared to D1. The post-thaw SM, SV and SPMI were above 50%, 65% and 55% with the diluents D2 and D3 but differed non-significant. The SAI 76.1 ± 1.1% was significantly higher (p < 0.05) with D3. We concluded that the use of a simple home-made Tris-based diluent containing 20% (v/v) egg yolk and 5% glycerol (v/v), two-step dilution and a three-step freezing technique is a sustainable and effective method for freezing ram semen. For further validation, the fertility of ewes artificially inseminated with the frozen semen will be observed.     

The influence of cryopreservation and quick-freezing on the mechanical properties of tendons

In order to maintain their native properties, cryopreserved tendons are usually used in biomechanical research and in transplantation of allogenic tendon grafts. The use of different study protocols leads to controversy in literature and thus complicates the evaluation of the current literature. The aim of this study consisted in examining the influence of different freezing and thawing temperatures on the mechanical properties of tendons. 60 porcine tendons were frozen at either −80 °C or −20 °C for 7 days and thawed at room or body temperature for 240 or 30 min, respectively. A subgroup of ten tendons was quick-frozen with liquid nitrogen (−196 °C) for 2 s before cryopreservation. Biomechanical testing was performed with a material testing machine and included creep, cyclic and load-to-failure tests. The results showed that freezing leads to a reduced creep strain after constant loading and to an increased secant modulus. Freezing temperature of −80 °C increased the secant modulus and decreased the strain at maximum stress, whereas thawing at room temperature reduced the maximum stress, the strain at initial tendon failure and the Young’s Modulus. Quick-freezing led to increased creep strain after constant loading, increased strain at initial failure in the load-to-failure test, and decreased strain at maximum stress. When cryopreserving, tendons for scientific or medical reasons, freezing temperature of −20 °C and thawing temperature of 37.5 °C are recommended to maintain the native properties of tendons. A treatment with liquid nitrogen in the sterilization process of tendon allografts is inadvisable because it alters the tendon properties negatively.     

Determination of cryothermal injury thresholds in tissues impacted by cardiac cryoablation

Despite widespread clinical use of cryoablation, there remain questions regarding dosing and treatment times which may affect efficacy and collateral injury. Dosing and treatment times are directly related to the degree of cooling necessary for effective lesion formation. Human and swine atrial, ventricular, and lung tissues were ablated using two cryoablation systems with concurrent infrared thermography. Post freeze-thaw samples were cultured and stained to differentiate viable and non-viable tissue. Matlab code correlated viability staining to applied freeze-thaw thermal cycles, to determine injury thresholds. Tissue regions were classified as live, injured, or dead based upon staining intensity at the lesion margin. Injury begins at rates of ∼10 °C/min to 0 °C, with non-viable tissue requiring cooling rates close to 100 °C/min to ∼ −22 °C for swine and significantly greater cooling to −26 °C for human tissue (p = 0.041). At similar rates, lung tissue injury began at 0 °C, with human tissue requiring significantly less cooling, to ∼ −15 °C for complete necrosis and −26 °C for swine (p = 0.024). Data suggest that there are no significant differences between swine and human myocardial response, but there may be differences between swine and human lung cryothermal tolerance.     

Evaluation of earth observation datasets for LST trends over India and its implication in global warming

Land surface temperature (LST) is crucial in surface energy balance, urban climatology, intensifying global change, ecological and environmental concerns. The present study examined the LST trends and spatio-temporal variation over India from 2002 to 2022. This includes comparison of LST for the summer and winter seasons over two decades. Secondly, the present study examined the LULC category wise LST variability during the day and night-time using MODIS (The Terra Moderate Resolution Imaging Spectroradiometer) derived products. This study explored the feasibility of cloud computing for big data analysis for LST distribution in seven landuse categories over India, providing a conceptual response to global warming. Results showed the existence of spatial LST variation due to changes in land-use patterns and MODIS derived vegetation indices- NDVI. Daytime LST for the summer and winter seasons of 2002 was found to be 45.17 °C and 39.13 °C, respectively. Outcomes illustrate declining trends in range (LST_min-LST_max) for winter seasons, initially, it was observed as 56.29 °C for 2002 while later on it was observed to be 20.21 °C and 20.87 °C for 2021 and 2022 respectively. The LST_min (summer) has shown an increasing trend towards upper LST values, from −3.01 °C to 12.21 °C from 2002 TO 2022. LST_min__winter has shown a rising trend towards the upper LST values from −17.16 °C to 9.15 °C in 2022. The maximum LST for the DRs was observed to be 61.56 °C, followed by UR as 56.24 °C. The findings demonstrate that daytime LST_min and LST_max are found to be 19.50 °C to 56.24 °C for UR, 29.5 °C to 61.56 °C for DR, 19.24 °C to 54.08 °C for SAR, −21.1 °C to 0.05 °C for SCR and 15 °C to 32.18 °C for FHR. NDVI-LST (daytime, nighttime and diurnal temperature range) feature space generates an obtuse triangle and depicts a negative correlation of vegetation for a few LULC categories. The outcomes indicated that desert and snow regions have highest LST_max followed by urban and semiarid regions during daytime. During the nighttime, desert and urban regions have the highest temperature followed by semi-arid and forest regions. The outcomes support the efficacy of earth observation datasets and help to facilitate a better understanding of LULC and its impact on regional climate.     

Effect of ambient temperature on female endurance performance

Ambient temperature can affect physical performance, and an ambient temperature range of −4 °C to 11 °C is optimal for endurance performance in male athletes. The few similar studies of female athletes appear to have found differences in response to cold between the genders. This study investigated whether ambient temperature affects female endurance performance. Nine athletes performed six tests while running on a treadmill in a climatic chamber at different ambient temperatures: 20, 10, 1, −4, −9 and −14 °C and a wind speed of 5 m s⁻¹. The exercise protocol consisted of a 10-min warm-up, followed by four 5-min intervals at increasing intensities at 76%, 81%, 85%, and 89% of maximal oxygen consumption. This was followed by an incremental test to exhaustion. Although peak heart rate, body mass loss, and blood lactate concentration after the incremental test to exhaustion increased as the ambient temperature rose, no changes in time to exhaustion, running economy, running speed at lactate threshold or maximal oxygen consumption were found between the different ambient temperature conditions. Endurance performance during one hour of incremental exercise was not affected by ambient temperature in female endurance athletes.     

Cold tolerance of the maize orange leafhopper,Cicadulina bipunctata

Cicadulina bipunctata was originally distributed in tropical and subtropical regions of the Old World. This leafhopper recently expanded its distribution area to southern parts of temperate Japan. In this study, factors affecting the overwintering ability of C. bipunctata were examined. A series of laboratory experiments revealed that cold acclimation at 15 °C for 7 days enhanced the cold tolerance of C. bipunctata to the same level as an overwintering population, adult females were more tolerant of cold temperature than adult males, and survival of acclimated adult females was highly dependent on temperature from −5 to 5 °C and exposure duration to the temperature. The temperature of crystallization of adult females was approximately −19 °C but temperatures in southern temperate Japan rarely dropped below −10 °C in the winter, indicating that overwintering C. bipunctata adults in temperate Japan are not killed by freezing injury but by indirect chilling injury caused by long-term exposure to moderately low temperatures. An overwintering generation of C. bipunctata had extremely low overwinter survival (<1%) in temperate Japan; however, based on winter temperature ranges, there are additional areas amenable to expansion of C. bipunctata in temperate Japan.     

Impact of In-Situ CO2 Nano-Bubbles Generation on Freezing Parameters of Selected Liquid Foods

The impact of in-situ CO₂ nano-bubbles generation on the freezing properties of soft serve, milk, and apple juice was investigated. Carbonated (0, 1000, and 2000 ppm) liquid foods contained in a tube were submerged and cooled for 90 min in a pre-set ethylene glycol bath (−15 °C). Before the enclosed liquid reached 0 °C, the vibration was discharged through ultrasound in the bath to create nano-bubbles within the carbonated food samples, and the changes in temperature for 90 min of each food were recorded as a freezing curve. The time for onset of nucleation of control soft serve mix was halved in samples with 2000-ppm CO₂ due to the presence of nano-bubbles. Likewise, the nucleation time for milk with and without nano-bubbles at the same CO₂ concentration of 2000 ppm was 7.9 ± 0.1 and 2.8 ± 0.8 min_, respectively. The generation of CO₂ nano-bubbles from 2000-ppm CO₂ level in 10 ^oBx apple juice displayed −9.3 ± 0.3 °C nucleation temperature while the control one had −11.7 ± 0.9 °C.

     

Adult plasticity of cold tolerance in a continental-temperate population of Drosophila suzukii

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a worldwide emerging pest of soft fruits, but its cold tolerance has not been thoroughly explored. We determined the cold tolerance strategy, low temperature thermal limits, and plasticity of cold tolerance in both male and female adult D. suzukii. We reared flies under common conditions (long days, 21 °C; control) and induced plasticity by rapid cold-hardening (RCH, 1 h at 0 °C followed by 1 h recovery), cold acclimation (CA, 5 days at 6 °C) or acclimation under fluctuating temperatures (FA). D. suzukii had supercooling points (SCPs) between −16 and −23 °C, and were chill-susceptible. 80% of control flies were killed after 1 h at −7.2 °C (males) or −7.5 °C (females); CA and FA improved survival of this temperature in both sexes, but RCH did not. 80% of control flies were killed after 70 h (male) or 92 h (female) at 0 °C, and FA shifted this to 112 h (males) and 165 h (females). FA flies entered chill coma (CT_min) at approximately −1.7 °C, which was ca. 0.5 °C colder than control flies; RCH and CA increased the CT_min compared to controls. Control and RCH flies exposed to 0 °C for 8 h took 30–40 min to recover movement, but this was reduced to <10 min in CA and FA. Flies placed outside in a field cage in London, Ontario, were all killed by a transient cold snap in December. We conclude that adult phenotypic plasticity is not sufficient to allow D. suzukii to overwinter in temperate habitats, and suggest that flies could overwinter in association with built structures, or that there may be additional cold tolerance imparted by developmental plasticity.     

Explicit formula of finite difference method to estimate human peripheral tissue temperatures during exposure to severe cold stress

During cold exposure, peripheral tissues undergo vasoconstriction to minimize heat loss to preserve the maintenance of a normal core temperature. However, vasoconstricted tissues exposed to cold temperatures are susceptible to freezing and frostbite-related tissue damage. Therefore, it is imperative to establish a mathematical model for the estimation of tissue necrosis due to cold stress. To this end, an explicit formula of finite difference method has been used to obtain the solution of Pennes' bio-heat equation with appropriate boundary conditions to estimate the temperature profiles of dermal and subdermal layers when exposed to severe cold temperatures. The discrete values of nodal temperature were calculated at the interfaces of skin and subcutaneous tissues with respect to the atmospheric temperatures of 25 °C, 20 °C, 15 °C, 5 °C, −5 °C and −10 °C. The results obtained were used to identify the scenarios under which various degrees of frostbite occur on the surface of skin as well as the dermal and subdermal areas. The explicit formula of finite difference method proposed in this model provides more accurate predictions as compared to other numerical methods. This model of predicting tissue temperatures provides researchers with a more accurate prediction of peripheral tissue temperature and, hence, the susceptibility to frostbite during severe cold exposure.     

The efficacy of ice recrystallization inhibitors in rat lung cryopreservation using a low cost technique for ex vivo subnormothermic lung perfusion

Although lung transplant remains the only option for patients with end-stage lung failure, short preservation times result in an inability to meet patient demand. Successful cryopreservation may ameliorate this problem; however, very little research has been performed on lung cryopreservation due to the inability to prevent ice nucleation or growth. Therefore, this research sought to characterize the efficacy of a small-molecule ice recrystallization inhibitor (IRI) for lung cryopreservation given its well-documented ability to control ice growth.Sprague-Dawley heart-lung blocks were perfused at room temperature using a syringe-pump. Cytotoxicity of the IRI was assessed through the subsequent perfusion with 0.4% (w/v) trypan blue followed by formalin-fixation. Ice control was assessed by freezing at a chamber rate of −5 °C/min to −20 °C and cryofixation using a low-temperature fixative. Post-thaw cell survival was determined by freezing at a chamber rate of −5 °C/min to −20 °C and thawing in a 37 °C water bath before formalin-fixation. In all cases, samples were paraffin-embedded, sliced, and stained with eosin.The IRI studied was found to be non-toxic, as cell membrane integrity following perfusion was not significantly different than controls (p = 0.9292). Alveolar ice grain size was significantly reduced by the addition of this IRI (p = 0.0096), and the addition of the IRI to DMSO significantly improved post-thaw cell membrane integrity when compared to controls treated with DMSO alone (p = 0.0034).The techniques described here provide a low-cost solution for rat ex vivo lung perfusion which demonstrated that the ice control and improved post-thaw cell survival afforded by IRI-use warrants further study.     

Saccharomycomorpha psychra n. g., n. sp., a Novel Member of Glissmonadida (Cercozoa) Isolated from Arctic and Antarctica

A novel genus and species within the order Glissmonadida (Cercozoa, Rhizaria), Saccharomycomorpha psychra n. g., n. sp., is described from lichen in the Ny-Ålesund region (High Arctic) and moss in the Fildes peninsula of King George Island (Maritime Antarctica). Cells were spherical and did not appear to present flagella in organic-rich Potato Dextrose Agar medium where they were able to feed osmotrophically. Molecular phylogenetic analyses based on 18S rRNA gene sequence demonstrated that Saccharomycomorpha psychra belong to “clade T” within the order Glissmonadida (Cercozoa, Rhizaria). All three investigated strains could grow at 4 °C and had an optimum growth temperature of 12 °C, 20 °C, and 20 °C, while a maximum growth temperature of 20 °C, 20 °C, and 25 °C, respectively. In conclusion, we established the phenotypic identity of “clade T,” which until now was exclusively detected by environmental sequences, and erect a new family Saccharomycomorphidae for “clade T.” Nomenclatural, morphological and ecological aspects of this novel species are discussed.     

Turning up the heat on subzero fish: thermal dependence of sustained swimming in an Antarctic notothenioid

We determined the maximum sustained swimming speed (U_crit), and resting and maximum ventilation rates of the Antarctic fish Pagothenia borchgrevinki at five temperatures between −1°C and 8°C. We also determined resting metabolic rate (VO₂) at −1°C, 2°C, and 4°C. U_crit of P. borchgrevinki was highest at −1°C (2.7±0.1 BL s⁻¹) and rapidly decreased with temperature, representing a thermal performance breadth of only 5°C. This narrow thermal performance supports our prediction that specialisation to the subzero Antarctic marine environment is associated with a physiological trade-off in performance at high temperatures. Resting oxygen consumption and ventilation rate increased by more than 200% across the temperature range, which most likely contribute to the decrease in aerobic swimming capabilities at higher temperatures.