This study presents a computational framework for thermomechanical stress analysis in a specimen undergoing cryopreservation, with emphasis on radiofrequency (RF) heating for recovering from cryogenic storage. In particular, this study addresses cryopreservation by vitrification, where the specimen is stored in the amorphous phase (vitreous means glassy). In broad terms, the relatively high cooling and rewarming rates necessary for vitrification result in differential thermal expansion in the specimen, which is the driving force for thermomechanical stress. Thermomechanical stress can lead to structural damage, such as fractures or plastic deformation, rendering the specimen useless. Not without technical difficulties, those hazardous effects during the rewarming phase of the protocol can be mitigated by applying volumetric heating, with RF heating as an attractive means. The proposed computational framework in this study addresses the coupled electromagnetic, thermal and solid mechanics fields, using commercially available solvers. This study advances from a spherical-case benchmark to realistic models of the rabbit kidney and the human kidney. Results of this study suggest that structural damage to the brittle material can be prevented when stress relaxation is facilitated around the glass transition temperature. Furthermore, this study suggests that volumetric heating is necessary to surpass the critical rewarming rate, while benefiting from lowering the overall thermomechanical stress during recovery from cryogenic storage. More broadly, the computational framework presented here can be used for the optimization of the RF heating parameters, chamber specifics, specimen container shape, and the thermal protocol in order to preserve structural integrity in the specimen.The development of semen cryopreservation strategies is necessary to improve the semen storage technologies of species of great commercial interest for aquaculture. Recent studies demonstrate that lipids play an important role in the fertility and cryotolerance of fish gametes. This study investigated the effect of exogenous lipids in the freezing medium on the post-thaw functional parameters of Salmo salar spermatozoa. Semen samples (n = 12) were incubated in standard extender supplemented with different concentrations of oleic acid (OA, C181n9), linoleic acid (LA, C182n6), arachidonic acid (ARA, C204n6) and cholesterol-loaded cyclodextrin (CLC). Post-thaw motility, membrane integrity, mitochondrial membrane potential (ΔΨm), superoxide anion (O2•-) and fertility rates were analyzed. The results revealed that the semen incubated with 0.003 mmol/L OA increased the motility (~7%) and ΔΨm (~2%) (P less then 0.05), but membrane integrity and fertility were not increased. The addition of 0.003 mmol/L LA increased the motility (~4%) and all LA extenders increased the ΔΨm (P less then 0.05); however, LA increased the O2•- levels and decreased the membrane integrity and fertility (P less then 0.05). Semen incubated with ARA improved sperm motility (~5%), membrane integrity (~10.5%) and fertility rates (~11%) (P less then 0.05). The maximum improvement in post-thaw sperm functionality was observed by adding 0.003 mmol/L ARA. In contrast, sperm quality parameters and fertility were decreased by the CLC addition (P less then 0.05). This study showed that ARA could be considered as an additive for semen cryopreservation and could be relevant in the reproductive process and reproductive management of Salmo salar.Accidental hypothermia is associated with increased risk for arrhythmias. QRS/QTc is proposed as an ECG-marker, where decreasing values predict hypothermia-induced ventricular arrhythmias. If reliable it should also predict nonappearance of arrhythmias, observed in species like rat that regularly tolerate prolonged hypothermia. A rat model designed for studying cardiovascular function during cooling, hypothermia and subsequent rewarming was chosen due to species-dependent resistance to ventricular arrhythmias. ECG was recorded throughout the protocol. No ventricular arrhythmias occurred during experiments. QRS/QTc increased throughout the cooling period and remained above normothermic baseline until rewarmed. Different from the high incidence of hypothermia-induced ventricular arrhythmias in accidental hypothermia patients, where QRS/QTc ratio is decreased in moderate hypothermia; hypothermia and rewarming of rats is not associated with increased risk for ventricular fibrillation. This resistance to lethal hypothermia-induced arrhythmias was predicted by QRS/QTc.Stomach cancer is one of the most common cancers in the world. https://www.selleckchem.com/products/amg-232.html The relationship between alcohol consumption and the risk of stomach cancer remains unclear. Epidemiology studies investigating this relationship have shown inconsistent findings. A meta-analysis was performed to explore the association between alcohol consumption and increased stomach cancer risk. Eighty-one epidemiology studies, including 68 case-control studies and 13 cohort studies, were included in this study. A significant association was found between alcohol consumption and increased risk of stomach cancer (OR = 1.20, 95% CI 1.12-1.27). To explore the source of the significant heterogeneity (p less then 0.05, I2 = 86%), analysis was stratified by study type (case-control study and cohort study), control type (hospital-based control and population-based control), gender (male, female, and mix), race (White and Asian), region (United States, Sweden, China, Japan), subsite of stomach cancer, and type of alcohol. The stratified analyses found that region and cancer subsite are major sources of the high heterogeneity. The inconsistent results in different regions and different subsites might be related to smoking rates, Helicobacter pylori infection, obesity, and potential genetic susceptibility. The positive association between drinking and increased risk of stomach cancer is consistent in stratified analyses. The dose-response analysis showed a clear trend that a higher daily intake of alcohol is associated with a higher risk of stomach cancer.
This study presents a computational framework for thermomechanical stress analysis in a specimen undergoing cryopreservation, with emphasis on radiofrequency (RF) heating for recovering from cryogenic storage. In particular, this study addresses cryopreservation by vitrification, where the specimen is stored in the amorphous phase (vitreous means glassy). In broad terms, the relatively high cooling and rewarming rates necessary for vitrification result in differential thermal expansion in the specimen, which is the driving force for thermomechanical stress. Thermomechanical stress can lead to structural damage, such as fractures or plastic deformation, rendering the specimen useless. Not without technical difficulties, those hazardous effects during the rewarming phase of the protocol can be mitigated by applying volumetric heating, with RF heating as an attractive means. The proposed computational framework in this study addresses the coupled electromagnetic, thermal and solid mechanics fields, using commercially available solvers. This study advances from a spherical-case benchmark to realistic models of the rabbit kidney and the human kidney. Results of this study suggest that structural damage to the brittle material can be prevented when stress relaxation is facilitated around the glass transition temperature. Furthermore, this study suggests that volumetric heating is necessary to surpass the critical rewarming rate, while benefiting from lowering the overall thermomechanical stress during recovery from cryogenic storage. More broadly, the computational framework presented here can be used for the optimization of the RF heating parameters, chamber specifics, specimen container shape, and the thermal protocol in order to preserve structural integrity in the specimen.The development of semen cryopreservation strategies is necessary to improve the semen storage technologies of species of great commercial interest for aquaculture. Recent studies demonstrate that lipids play an important role in the fertility and cryotolerance of fish gametes. This study investigated the effect of exogenous lipids in the freezing medium on the post-thaw functional parameters of Salmo salar spermatozoa. Semen samples (n = 12) were incubated in standard extender supplemented with different concentrations of oleic acid (OA, C181n9), linoleic acid (LA, C182n6), arachidonic acid (ARA, C204n6) and cholesterol-loaded cyclodextrin (CLC). Post-thaw motility, membrane integrity, mitochondrial membrane potential (ΔΨm), superoxide anion (O2•-) and fertility rates were analyzed. The results revealed that the semen incubated with 0.003 mmol/L OA increased the motility (~7%) and ΔΨm (~2%) (P less then 0.05), but membrane integrity and fertility were not increased. The addition of 0.003 mmol/L LA increased the motility (~4%) and all LA extenders increased the ΔΨm (P less then 0.05); however, LA increased the O2•- levels and decreased the membrane integrity and fertility (P less then 0.05). Semen incubated with ARA improved sperm motility (~5%), membrane integrity (~10.5%) and fertility rates (~11%) (P less then 0.05). The maximum improvement in post-thaw sperm functionality was observed by adding 0.003 mmol/L ARA. In contrast, sperm quality parameters and fertility were decreased by the CLC addition (P less then 0.05). This study showed that ARA could be considered as an additive for semen cryopreservation and could be relevant in the reproductive process and reproductive management of Salmo salar.Accidental hypothermia is associated with increased risk for arrhythmias. QRS/QTc is proposed as an ECG-marker, where decreasing values predict hypothermia-induced ventricular arrhythmias. If reliable it should also predict nonappearance of arrhythmias, observed in species like rat that regularly tolerate prolonged hypothermia. A rat model designed for studying cardiovascular function during cooling, hypothermia and subsequent rewarming was chosen due to species-dependent resistance to ventricular arrhythmias. ECG was recorded throughout the protocol. No ventricular arrhythmias occurred during experiments. QRS/QTc increased throughout the cooling period and remained above normothermic baseline until rewarmed. Different from the high incidence of hypothermia-induced ventricular arrhythmias in accidental hypothermia patients, where QRS/QTc ratio is decreased in moderate hypothermia; hypothermia and rewarming of rats is not associated with increased risk for ventricular fibrillation. This resistance to lethal hypothermia-induced arrhythmias was predicted by QRS/QTc.Stomach cancer is one of the most common cancers in the world. https://www.selleckchem.com/products/amg-232.html The relationship between alcohol consumption and the risk of stomach cancer remains unclear. Epidemiology studies investigating this relationship have shown inconsistent findings. A meta-analysis was performed to explore the association between alcohol consumption and increased stomach cancer risk. Eighty-one epidemiology studies, including 68 case-control studies and 13 cohort studies, were included in this study. A significant association was found between alcohol consumption and increased risk of stomach cancer (OR = 1.20, 95% CI 1.12-1.27). To explore the source of the significant heterogeneity (p less then 0.05, I2 = 86%), analysis was stratified by study type (case-control study and cohort study), control type (hospital-based control and population-based control), gender (male, female, and mix), race (White and Asian), region (United States, Sweden, China, Japan), subsite of stomach cancer, and type of alcohol. The stratified analyses found that region and cancer subsite are major sources of the high heterogeneity. The inconsistent results in different regions and different subsites might be related to smoking rates, Helicobacter pylori infection, obesity, and potential genetic susceptibility. The positive association between drinking and increased risk of stomach cancer is consistent in stratified analyses. The dose-response analysis showed a clear trend that a higher daily intake of alcohol is associated with a higher risk of stomach cancer.
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