Cold Bath Research Articles

Experimental Investigation on the Effect of Salt Solution on the Soil Freezing Characteristic Curve for Expansive Soils

With the development of the Belt and Road Initiative in China, high-speed railways are booming and inevitably pass through seasonal frost regions. In Nanyang basin, due to seasonal changes, railway subgrades will undergo frost heaving and thawing subsidence. The freezing characteristics of the soil are characterized by the freezing characteristic curve, and the important factors affecting the freezing characteristic curve are the content of expansive clay minerals in the soil and the salt solution. Therefore, three soil samples with different montmorillonite contents were saturated with salt solutions of different concentrations, and the freezing temperature of the soil samples was controlled by a cold bath. After the temperature equilibrium, the frozen stable soil samples were put into a nuclear magnetic resonance instrument to test the unfrozen water content, and the relationship between the freezing temperature and the unfrozen water content of expansive soil under different salt solution concentrations was obtained. Additionally, a unified model was used to simulate the test results. The results show that SFCC shifts to the left, that is, the sodium chloride salt solution reduces the freezing point of the soil sample so that it has more unfrozen water at the same temperature. At the same time, the soil’s freezing characteristic curves are closely related to content of expansive clay minerals in the soil. The more expansive clay mineral content, the greater the corresponding unfrozen water content. These results provide some basic insights for improving the frost heave and thaw subsidence problems of railway subgrades in seasonal permafrost regions, which will have a positive impact on promoting the management and rational application of land resources and the promotion of sustainable development.

Mechanism of Danggui Sini Decoction in improving kidney injury caused by blood stasis syndrome based on metabolomics and network pharmacology

This article analyzed the mechanism of Danggui Sini Decoction(DSD) in improving kidney injury caused by blood stasis syndrome(BSS) in rats. Firstly, 32 female SD rats were randomly divided into the following four groups: a normal group and a BSS group, both receiving an equal amount of distilled water by gavage; a normal+DSD group and a BSS+DSD group, both receiving 5.103 g·kg~(-1) DSD orally for a total of 14 days. Daily cold water bath was given to establish the BSS model, and on the 14th day, BSS rats were subcutaneously injected with 0.8 mg·kg~(-1) adrenaline. Normal rats were subjected to the water bath at 37 ℃ and injected with an equal volume of distilled water. After the experiment, 24-hour urine, serum, and kidney samples were collected for metabolomic analysis, biochemical measurements, and hematoxylin-eosin(HE) staining. The study then employed ~1H-NMR metabolomic technology to reveal the metabolic network regulated by DSD in improving BSS-induced kidney injury and used network pharmacology to preliminarily elucidate the key targets of the effectiveness of DSD. Pathological and biochemical analysis showed that DSD intervention significantly reduced inflammation and abnormal levels of blood creatinine, blood urea nitrogen, and urine protein in the kidneys. Metabolomic analysis indicated that DSD attenuated BSS-induced kidney injury primarily by regulating 10 differential metabolites and three major metabolic pathways(taurine and hypotaurine metabolism, citrate cycle, and acetaldehyde and dicarboxylic acid metabolism). Network pharmacology analysis suggested that the protective effect of DSD against BSS-induced kidney injury might be related to two key genes, ATP citrate lyase(ACLY) and nitric oxide synthase 2(NOS2), and two main metabolic pathways, i.e., arginine biosynthesis, and arginine and proline metabolism. This study, from the perspective of network regulation, provides initial insights and evidence into the mechanism of DSD in improving kidney injury induced by BSS, offering a basis for further investigation into the molecular mechanisms underlying its efficacy.

Simple Preservation of Single Cells (SENSE): One-Step Robust Whole Blood Cryopreservation Method Enables the Generation of High-Quality Single-Cell Immune Profiles

Introduction: Single-cell profiling (SCP) has revolutionized our understanding of cellular and molecular states in health and disease. Current multistep methods for cryopreserving single-cell suspensions from blood for single-cell RNA sequencing (scRNA-seq) are time-consuming, require trained personnel and special equipment, limiting their clinical adoption and sample collection/availability. It is critical to develop protocols for efficient capture of precious clinical samples/implementation of SCP in clinics. We developed and validated the Simple prEservatioN of Single cElls (SENSE) method for single-step cryopreservation of whole blood (WB), which, along with granulocyte depletion during single-cell assay, generates high-quality SCPs. Methods: Blood samples (n=6) were split into two parts and cryopreserved using the SENSE and peripheral blood mononuclear cells (PBMC) methods. In the SENSE method, WB was cryopreserved by mixing 1:1 blood and freezing solution (80% FBS, 20% DMSO) and granulocytes removed using EasySep CD15 positive selection kit. For PBMC method, density-gradient method was employed for isolating PBMCs followed by cryopreservation. Single cell assay was performed using 10x Genomics kits. The raw sequencing reads were aligned using 10x Genomics Cell Ranger (Zheng et al., Nat. Comm., 2017) to the reference human genome, and the gene-expression matrices were analyzed using the Seurat package (Hao et al., Cell, 2021). Cell markers were identified by comparing target cell types with others using the Wilcoxon Rank Sum test (adjusted P<.10, average log2FC>0.25, percent cell expression>25%). Potential doublets were marked using the doubletFinder (McGinnis et al., Cell Syst., 2019) algorithm and batch-effect was quantified using Shannon entropy calculated by the CellMixS (Lutge et al., Life Sci Alliance. 2021) package for quality assessment of two methods. Cellular communications were assessed using CellChat, which measures cell-to-cell interactions based on the ligands and receptors expression (Jin et al., Nature Comm., 2021). Results: Highly viable (86.3±1.51%) single-cell suspensions (22,353 cells) were obtained from the SENSE method's WB cryopreserved samples. The captured median gene counts, unique molecular identifiers (UMIs)/cell, and mitochondrial content were comparable between the two methods. Similar proportions of membrane, extracellular, and ribosomal ontology-related genes demonstrated the robustness of the SENSE method in capturing high-quality cells without introducing cellular damage artifacts. Lower doublets (2.4%) were observed with the SENSE method compared to the PBMC method (4.8%). These rigorous quality assessments demonstrated the effectiveness of the SENSE method for obtaining high-quality cells for SCP. Both methods yielded similar transcriptomic profiles with split UMAPs of the integrated scRNA-seq data revealing similar clustering patterns except for some variations in the myeloid cells and T-cells clusters. The SENSE method cryopreserved samples exhibited significantly higher T-cell enrichment, enabling deeper characterization of T-cell subtypes. The functional landscape of T/NK cells was assessed using the CellChat tool. Most pathways showed a similar information flow pattern, indicating the capture of similar signaling networks between the cells processed using either of the two methods. However, the SENSE method captured lower number of myeloid cells, attributable to filtering out of sticky CD15+ myeloid/granulocytes that resulted in the loss of single-cells captured. Nevertheless, the SENSE method recapitulated the myeloid compartment associated with the disease as we observed similar patient-wise differences in cell types from both methods. Finally, we compared the transcriptome profiles of both methods to a publicly available PBMC dataset (Zheng et al., Nat. Comm., 2017). Concordance between the three datasets was observed, with all cell types being consistently identified using key marker gene expression. Conclusions: Comparative analysis of scRNA-seq datasets obtained with the two cryopreservation methods, i.e., SENSE and PBMC methods, yielded similar cellular and molecular profiles, confirming the suitability of the former method's incorporation in clinics/labs for cryopreserving and obtaining high-quality single-cells for conducting critical translational research.

Beyond the cold baths: contemporary applications of cold-water immersion in the treatment of clinical depression and anxiety

SUMMARYCold-water immersion (e.g. adapted cold showers, partial or whole-body immersion, cold swimming) are nowadays increasingly being used as an adjunctive procedure to enhance the effects of primary treatment of various clinical conditions, including depressive and anxiety disorders. This brief article reviews the evidence regarding the beneficial effects of cold-water immersion on clinical depression and anxiety and outlines potential therapeutic mechanisms underlying the intervention. Promising avenues for future research and best practice recommendations are also discussed to improve the clinical effectiveness of cold-water immersion.

Cryopreserved red blood cells maintain allosteric control of oxygen binding when utilizing trehalose as a cryoprotectant

One of the most common life-saving medical procedures is a red blood cell (RBC) transfusion. Unfortunately, RBCs for transfusion have a limited shelf life after donation due to detrimental storage effects on their morphological and biochemical properties. Inspired by nature, a biomimetics approach was developed to preserve RBCs for long-term storage using compounds found in animals with a natural propensity to survive in a frozen or desiccated state for decades. Trehalose was employed as a cryoprotective agent and added to the extracellular freezing solution of porcine RBCs. Slow cooling (−1 °C min−1) resulted in almost complete hemolysis (1 ± 1 % RBC recovery), and rapid cooling rates had to be used to achieve satisfactory cryopreservation outcomes. After rapid cooling, the highest percentage of RBC recovery was obtained by plunging in liquid nitrogen and thawing at 55 °C, using a cryopreservation solution containing 300 mM trehalose. Under these conditions, 88 ± 8 % of processed RBCs were recovered and retained hemoglobin (14 ± 2 % hemolysis). Hemoglobin's oxygen-binding properties of cryopreserved RBCs were not significantly different to unfrozen controls and was allosterically regulated by 2,3-bisphosphoglycerate. These data indicate the feasibility of using trehalose instead of glycerol as a cryoprotective compound for RBCs. In contrast to glycerol, trehalose-preserved RBCs can potentially be transfused without time-consuming washing steps, which significantly facilitates the usage of cryopreserved transfusible units in trauma situations when time is of the essence.

Solid-State NMR Spectroscopy to Probe State and Phase Transitions in Frozen Solutions.

Freezing is commonly encountered during the processing and storage of biomacromolecule products. Therefore, understanding the phase and state transitions in pharmaceutical frozen solutions is crucial for the rational development of biopharmaceuticals. Solid-state nuclear magnetic resonance spectroscopy (ssNMR) was used to analyze solutions containing sodium phosphate buffer, histidine, and trehalose. Upon freezing, crystallization of disodium phosphate hydrogen dodecahydrate (Na2HPO4·12H2O, DPDH) and histidine was identified using 31P and 13C ssNMR, respectively, and confirmed by synchrotron X-ray diffractometry (SXRD). Using histidine as a molecular probe and based on the chemical shifts of atoms of interest, the pH of the freeze concentrate was measured. The unfrozen water content in freeze concentrates was quantified by 1H single pulse experiments. 13C-insensitive nuclei enhancement by polarization transfer (INEPT) and cross-polarization (CP) experiments were used as orthogonal tools to characterize the solutes in a "mobile" and a more "solid-like" state in the freeze-concentrated solutions, respectively. The above analyses were applied to a commercial monoclonal antibody (mAb) formulation of dupilumab. This work further establishes ssNMR spectroscopy as a highly capable biophysical tool to investigate the attributes of biopharmaceuticals and thereby provide insights into process optimization and formulation development.

Variation of serum serotonin values under specific peloidotherapy in patients with degenerative pathology of the lumbar spine

Serotonin is well known to be involved in the mediation of cognitive processes, but also in the regulation of multiple distinct physiological processes, such as pain. It is also involved in the modulation of nociception of the endogenous analgesic system. Among the monoamine neurotransmitters, serotonin plays an important role in signaling chronic pain, hence the importance of its monitoring in lumbar pain due to degenerative pathology, one of the common cause of this kind of pain. The aim of our study is to evaluate the impact of peloidotherapy on the variation of serum serotonin levels in patients with degenerative low back pain. In our study, conducted in Balneal and Rehabilitation Sanatorium of Techirghiol, we evaluated 130 patients who performed balneal and physical treatments for a period of 2 weeks. The patients were divided into 3 groups: 51 patients were enrolled into the hot mud baths group (HMB), 48 in the cold mud baths (CMB) group and 31 in the control group (CG). Each patient performed physiotherapy treatments which includes electrotherapy, massage and kinetotherapy, patients from HMB group had also hot mud therapy and patients from CMB group had cold mud therapy. Serum serotonin was dosed at admission and at discharge, for each patient, and was determined using ELISA method with kits from Demeditec Diagnostics GmbH for human serotonin. All the data from the study were statistically analized using the SPSS 22.0 program, values were interpreted as mean value and standard deviation, and we used ANOVA and t tests. The statistically significant value considered was p<0.05.

Quantum Otto heat engine with Pöschl–Teller potential in contact with coherent thermal bath

Work and efficiency of quantum Otto heat engines (QOHEs) can increase by using non-thermal baths or by inhomogeneous scaling of energy levels of the working substance. Given these points, at first, we construct the coherent thermal state for a trigonometric Pöschl–Teller (PT) potential. Then using a particle in this potential, which has unequally spaced energy levels, as a working substance, we investigate the work extraction and the efficiency of QOHEs that operates between cold and hot coherent thermal baths. The results show that changing the PT potential parameters in the adiabatic processes of QOHE, which causes an inhomogeneous shift in energy levels or/and make use of the hot coherent thermal bath, improve work extraction and efficiency of QOHE relative to the classical counterpart.

Influence winter swimming on post-exercise regeneration and quality of life of people practicing recreational sports

Entry Swimming is a stress factor for the body, depending on the level of adaptation to this stimulus, there may be different reactions of the body. Therefore, the contraindications and risks of immersion in cold water, such as drowning or hypothermia, should be taken into account. The study was aimed at assessing the impact of cold baths on well-being and post-exercise regeneration. Materials and methods The study involved 244 people who regularly practice recreational sports and swim. Conclusions Swimming has a positive effect on well-being and post-workout regeneration. It is important to conduct more research to obtain the data needed to determine the long and short term effects of swimming in the context of recreational activities.

Identification of chemical constituents of Qingjin Yiqi granules and comparative study on pharmacokinetics of 23 main bioactive components in normal and Lung-Qi deficiency rats by UPLC-MS/MS method

Qingjin Yiqi granules (QJYQ granules) are hospital preparations derived from ancient prescriptions under the guidance of academician Zhang Boli; they have the effect of invigorating qi and nourishing yin, strengthening the spleen and harmonizing the middle, clearing heat, and drying dampness, and are mainly used for patients with coronavirus disease 2019 (COVID-19) during the recovery period. However, their chemical constituents and pharmacokinetic characteristics in vivo have not been systematically investigated. In this study, 110 chemical constituents of QJYQ granules were identified using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), and a fast and sensitive ultra-high-performance liquid chromatography-mass spectrometry method was developed and validated for the target analytes. A rat model of lung-qi deficiency was established by subjecting mice to passive smoking combined with cold baths, and 23 main bioactive components of QJYQ granules were analyzed in normal and model rats after oral administration. The results showed that, compared to the normal group, there were significant differences in the pharmacokinetics of baicalin, schisandrin, ginsenoside Rb1, naringin, hesperidin, liquiritin, liquiritigenin, glycyrrhizic acid, and hastatoside in the model rats (P < 0.05), indicating that the in vivo processes of the above components changed under pathological conditions, suggesting that they may have pharmacological effects as active components. This study has helped identify QJYQ particulate substances and further supports their clinical application..

Fluctuations and stability of a fast-driven Otto cycle

We investigate the stochastic dynamics of a thermal machine realized by a fast-driven Otto cycle. By employing a stochastic approach, we find that system coherences strongly affect fluctuations depending on the thermodynamic current. Specifically, we observe an increment in the system instabilities when considering the heat exchanged with the cold bath. On the contrary, the cycle precision improves when the system couples with the hot bath, where thermodynamic fluctuations reduce below the classical Thermodynamic Uncertainty Relation bound. Violation of the classical bound holds even when a dephasing source couples with the system. We also find that coherence suppression not only restores the cycle cooling but also enhances the convergence of fluctuation relations by increasing the entropy production of the reversed process. An additional analysis unveiled that the stochastic sampling required to ensure good statistics increases for the cooling cycle while downsizes for the other protocols. Despite the simplicity of our model, our results provide further insight into thermodynamic relations at the stochastic level.

Pain tolerance after stroke: The Tromsø study.

Stroke lesions might alter pain processing and modulation by affecting the widely distributed network of brain regions involved. We aimed to compare pain tolerance in stroke survivors and stroke-free persons in the general population, with and without chronic pain. We included all participants of the sixth and seventh wave of the population-based Tromsø Study who had been tested with the cold pressor test (hand in cold water bath, 3°C, maximum time 106 s in the sixth wave and 120 s in the seventh) and who had information on previous stroke status and covariates. Data on stroke status were obtained from the Tromsø Study Cardiovascular Disease Register and the Norwegian Stroke Register. Cox regression models were fitted using stroke prior to study attendance as the independent variable, cold pressor endurance time as time variable and hand withdrawal from cold water as event. Statistical adjustments were made for age, sex, diabetes, hypertension, hyperlipidaemia, body mass index and smoking. In total 21,837 participants were included, 311 of them with previous stroke. Stroke was associated with decreased cold pain tolerance time, with 28% increased hazard of hand withdrawal (hazard ratio [HR] 1.28, 95% CI 1.10-1.50). The effect was similar in participants with (HR 1.28, 95% CI 0.99-1.66) and without chronic pain (HR 1.29, 95% CI 1.04-1.59). Stroke survivors, with and without chronic pain, had lower cold pressor pain tolerance, with possible clinical implications for pain in this group. We found lower pain tolerance in participants with previous stroke compared to stroke-free participants of a large, population-based study. The association was present both in those with and without chronic pain. The results may warrant increased awareness by health professionals towards pain experienced by stroke patients in response to injuries, diseases and procedures.

Encapsulation of rat brain slices in agar gel solution for long-term and reversible cryopreservation

Earlier there was found activity of glutamatergic ionotropic α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPAR) and N-methyl-D-aspartate receptors (NMDAR) disturbed after prolonged cryopreservation of brain slices at temperature of -10 оС. To eliminate cryodamage of AMPAR and NMDAR, the slices were encapsulated in the special freezing solution (SFS). SFS consisted of agar at various concentrations (33, 44 and 50 %) and artificial cerebrospinal fluid (67, 56 and 50 %, respectively). This solution was used for long-term cryopreservation of slices (52 days, -10 оС). Alterations in amplitudes of AMPA and NMDA potentials in the slices after rewarming were studied. Recovery of AMPAR and NMDAR after cryopreservation of the slices in SFS was the most optimal when the agar concentration in SFS was 50 %. Cryopreservation of the slices in SFS with different agar concentrations predominantly promoted the development of long-term potentiation in 78 % of the tested slices. Thus, the encapsulation of brain slices in SFS contributes to the preservation of AMPAR and NMDAR activity during long-term and reversible cryopreservation.

Thermal biology and overwintering behavior of the red sunflower seed weevil (Coleoptera: Curculionidae).

Most natural mortality of the red sunflower seed weevil, Smicronyx fulvus LeConte (Coleoptera: Curculionidae), occurs while larvae overwinter in the soil. To test the hypothesis that S. fulvus mortality is related to low temperatures, experiments were used to (i) evaluate the temperature at which larvae freeze (= supercooling point [SCP]), (ii) assess possible vertical movement between entry into the soil in fall and adult emergence in summer, and (iii) determine if realistic soil temperatures could explain patterns of overwintering mortality. Mean SCP for groups of S. fulvus larvae differed between years and months, but only ranged from -20.93 to -22.68 °C. Most overwintering larvae were found within 6 cm of the soil surface, but larvae appeared to move 1-2 cm deeper between pairs of successive sample dates (September to January, January to April). Significant larval mortality that occurred between January and April 2021 was tentatively attributed to a period in February where daily minimum soil temperatures ranged from -8 to -12 °C. When overwintering under control conditions (constant 4 °C) was interrupted with week-long exposure to -4, -8, or -12 °C in a cold bath, significant S. fulvus mortality was seen for temperatures at or below -8 °C. Combined results suggest that mortality of overwintering S. fulvus is likely caused by continuous exposure to low temperatures that may not be cold enough to freeze larvae. Additionally, the shallow overwintering by S. fulvus supports the idea that routine farm management, including tillage and herbicide incorporation, may help limit populations of this sunflower pest.

Agar freezing solution for long-term cryopreservation of brain slices from non-hibernating animals

Our previous studies have shown that function of ionotropic glutamate receptors such as AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) and NMDA (N-methyl-D-aspartate) was impaired after long-term cryopreservation of brain slices at -10°C within 30-50 days. To elucidate the reasons for cryodamage to AMPA- and NMDA-dependent mechanisms, artificial cerebrospinal fluid (aCSF) solutions that contain agar at different concentrations (33, 44, and 50%) were used for cryopreservation of the rat olfactory cortex slices. After cryopreservation, the slices were warmed to 37°C and the amplitudes changes of AMPA and NMDA potentials, which reflected the activities of the AMPA and NMDA mechanisms, were evaluated; the results were compared with those obtained before cryopreservation. It was found that AMPA and NMDA potentials changed differently depending on the concentration of agar in artificial cerebrospinal fluid. In solutions with 33% agar, the amplitude of AMPA potentials increased by 60%, whereas, in contrast, the amplitude of NMDA potentials was equal to the values before cryopreservation. At agar concentration of 44% in the solution, the AMPA and NMDA amplitudes were increased by 70% and 80%, respectively. A complete recovery of the activities of AMPA and NMDA mechanisms was obtained after cryopreservation in a freezing solution with an agar concentration of 50%. Under these conditions, the amplitudes of the AMPA and NMDA potentials corresponded to those seen before cryopreservation. Thus, the results obtained indicate that agar added to the artificial cerebrospinal fluid solution is a cryoprotectant that protects AMPA- and NMDA-dependent mechanisms from cryoinjury. The freezing solution (artificial cerebrospinal fluid and agar) developed by us for cryopreservation of brain explants of non-hibernating animals will be used to create a cryobank of nervous tissue.

Emergence and History

Emergence and History

The impact of specific balneotherapy on the endocrine physio-pathological mechanism in obesity

Obesity is a complex, multifactorial metabolic pathology, within the path of modification of the endocrine system plays a significant role. Changes in growth hormone (GH) and in-sulin growth factor (IGF) have been associated with obesity in various ways, mainly through changes in GH-binding proteins, insulin and ghrelin levels. The balneal treat-ment with Techirghiol Romanian sapropelic mud has an important impact on the endo-crine system, primarily through the action on the hypothalamic-pituitary-adrenal axis. We investigated the secretory changes of the IGF-1 hormone that appeared after the balne-al treatment. It was a total number of 52 patients, divided into two groups: 1 group who performed the treatment with Techirghiol sapropelic mud at thermoneutrality tempera-tures - warm mud baths, and the second group who followed treatment with the balneal therapeutic factor in a thermal contrast regime - cold mud baths. We studied whether there are correlations between the body mass index (BMI) and the secretion of this hor-mone. We also determined the serum levels of blood glucose at admission and discharge. In the cold mud baths- thermal contrast therapy, can be observed a statistically significant increase in IGF-1 values during the balneal treatment (p = 0.044 &lt; α = 0.05). Comparative-ly, in the warm mud baths, the increase in serum IGF-1 reached values close to statistical significance at the end of the treatment (p = 0.067 &gt; α = 0.05). There were no statistically significant correlations between BMI and IGF-1 hormone secretion at admission and at discharge. The results showed a statistically significant decrease in blood glucose values determined at admission and discharge in the group that performed warm mud baths. The balneal treatment with sapropelic mud of Techirghiol lake, from Romania, through the impact on the endocrine system, on the hypothalamic-pituitary-adrenal axis, can be registered as a treatment with a natural therapeutic factor with an impact on obesity, ther-apy carried out within the parameters of metabolic safety, and the conduct of future re-search in this direction it will help develop new concepts and approaches to obesity.

MnO2-Induced Oxidation of Iodide in Frozen Solution.

Metal oxides play a critical role in the abiotic transformation of iodine species in natural environments. In this study, we investigated iodide oxidation by manganese dioxides (β-MnO2, γ-MnO2, and δ-MnO2) in frozen and aqueous solutions. The heterogeneous reaction produced reactive iodine (RI) in the frozen phase, and the subsequent thawing of the frozen sample induced the gradual transformation of in situ-formed RI to iodate or iodide, depending on the types of manganese dioxides. The freezing-enhanced production of RI was observed over the pH range of 5.0-9.0, but it decreased with increasing pH. Fulvic acid (FA) can be iodinated by I-/MnO2 in aqueous and frozen solutions. About 0.8-8.4% of iodide was transformed to organoiodine compounds (OICs) at pH 6.0-7.8 in aqueous solution, while higher yields (10.4-17.8%) of OICs were obtained in frozen solution. Most OICs generated in the frozen phase contained one iodine atom and were lignin-like compounds according to Fourier transform ion cyclotron resonance/mass spectrometry analysis. This study uncovers a previously unrecognized production pathway of OICs under neutral conditions in frozen environments.

Determination of the Concentration and Accumulation Time of Triplet Molecules in Frozen Solutions from Change in Phosphorescence Intensity

Determination of the Concentration and Accumulation Time of Triplet Molecules in Frozen Solutions from Change in Phosphorescence Intensity

Cryoprotective Characteristics of L-Carnosine Dipeptide (β-Alanyl-L-Histidine)

The dipeptide (β-alanyl-L-histidine) is found in significant amounts in the muscles and brain of mammals, especially in the olfactory structures. L-Carnosine exhibits many protective effects when exposed to various cytotoxic factors on cells. We used slices of the rat olfactory cortex to study the cryoprotective characteristics of L-carnosine during cryopreservation (CP). Changes in the activity of N-methyl-D-aspartate receptors (NMDAR) were analyzed during registration of NMDA potentials induced by electrical stimulation of the lateral olfactory tract. Brain slices were preincubated with L-carnosine (20 mM) in solution, frozen (−10°C), and after a long CP (30 days) they were warmed up to 37°C and changes in the amplitudes of NMDA potentials were determined. It was found that the dipeptide optimized the pH of the freezing solution after CP and retained the activity of NMDAR, determined by the amplitude of NMDA potentials. L-Carnosine after CP contributed to the dehydration of excess free water from the slices. The dipeptide inhibited the development of glutamate excitotoxicity in brain slices during CP and maintained normal NMDAR functioning. The data obtained prove that L-carnosine exhibits the properties of an endogenous cryoprotector in the nervous tissue.