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1.
Food Chem ; 366: 130614, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34304137

RESUMO

Understanding how starch constituent in frozen dough affected bread quality would be valuable for contributing to the frozen products with better quality. To elucidate the underlying mechanism, starch was fractionated from multiple freezing-thawing (F/T) treated dough and reconstituted with gluten. Results showed that F/T treatment destructed the molecular and supramolecular structures of starch, which were more severe as the F/T cycle increasing. These structural disorganizations made water molecules easier to permeate into the interior of starch granules and form hydrogen bonds with starch molecular chains, which elevated the peak, breakdown, setback and final viscosity of starch paste. In addition, F/T treatment resulted in decreased specific volume (from 1.54 to 0.90 × 103 m3/Kg) and increased hardness (from 42.98 to 52.31 N) for steamed bread. We propose the strengthened water absorption ability and accelerated intra- and inter-molecular rearrangement of starch molecules and weak stability of "starch-gluten matrices" would allow interpreting deteriorated bread quality.


Assuntos
Pão , Amido , Pão/análise , Farinha/análise , Congelamento , Glutens , Vapor
2.
Med J (Ft Sam Houst Tex) ; (Per 22-01/02/03): 24-32, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34940965

RESUMO

PURPOSE: Transcorneal freezing is a common technique used in rabbits to induce damage to the corneal endothelium. Previous studies have been performed with a range of freezing temperatures, times, and rabbit ages. Here, we aimed to characterize the aged rabbit endothelium after transcorneal freezing to establish an innate corneal endothelial cell regrowth rate and propose it as a mechanism for evaluation of therapeutic efficacy in rabbit models. METHODS: Central corneas of anesthetized New Zealand White rabbits (n=3) aged 18-24 months were exposed to nitrous oxide cooled probes for 30 seconds. Animals were assessed by in vivo confocal microscopy, applanation tonometry, specular microscopy, optical coherence tomography, and histology. The contralateral eye acted as a control. Images were taken immediately before and after injury and on days 2, 4, 7, 11, and 14. RESULTS: Following transcorneal freezing, there was a significant decrease in corneal endothelium density and a temporary increase in corneal thickness. Endothelial density decreased by 95% immediately after injury compared to controls and showed linear recovery over 14 days, reaching a 38% reduction by day 14. There was a significant increase in pleomorphism across all time points post-injury. Conversely, corneal thickness increased two days post injury but recovered at all later time points. Intraocular pressure was not affected throughout. CONCLUSIONS: This corneal endothelium injury platform is ideal for injury and therapeutic research as it can be rapidly performed, and has minimal impact on corneal thickness and intraocular pressure. Due to innate rabbit endothelial regrowth, it is vital to establish corneal endothelial recovery rate before evaluating therapeutics for efficacy in this model system.


Assuntos
Lesões da Córnea , Endotélio Corneano , Animais , Córnea , Células Endoteliais , Congelamento , Coelhos
3.
Food Chem ; 371: 131190, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34583175

RESUMO

Urea, sodium dodecyl sulfate (SDS) and ß-mercaptoethanol (2-ME) were used to monitor the roles of hydrogen bonds, hydrophobic interactions and disulfide bonds in frozen egg yolk. Yolk samples were prepared with a denaturant, and the textural characteristics, turbidity properties, protein patterns and structures were analysed. The results showed that SDS or 2-ME addition to egg yolk promoted its turbidity and texture properties, but urea changed the turbidity differently. SDS-PAGE results showed that yolk protein patterns with urea slightly reduced the amount of high molecular weight substances, whereas SDS and 2-ME addition increased the amount. ATR-FTIR spectroscopy revealed that the protein secondary structures changed from ordered structures to random coils. The texture properties were correlated with the protein secondary structure, especially ß-sheets and ß-turns. Thus, the three bond dissociation reagents induced protein denaturation. Hydrogen bonds were the critical force affecting frozen egg yolk gelation, followed by hydrophobic interactions and disulfide bonds.


Assuntos
Proteínas do Ovo , Gema de Ovo , Eletroforese em Gel de Poliacrilamida , Congelamento , Indicadores e Reagentes , Estrutura Secundária de Proteína
4.
Food Chem ; 370: 131264, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34788949

RESUMO

Supercooling can preserve beef without freezing damage, whereas maintaining the supercooled state is difficult. An innovative method of static magnetic field extended supercooling (SM-ES) was proposed to maintain the non-frozen state of beef. Effect of SM-ES (-4 °C + SMF) compared with refrigerated (4 °C), slow-frozen (-4 °C) and frozen (-18 °C) treatment on beef quality was investigated. Results demonstrated that SM-ES successfully preserved beef at -4 °C without ice nucleation for 14 days. The SEM images revealed that the microstructure of slow-frozen/frozen samples was damaged due to crystallizing, while the ice nucleation was not observed in SM-ES treated beef. Compared with refrigerated, slow-frozen and frozen treatment, the drip loss of SM-ES decreased by 21.9%, 47.8% and 30.9%, respectively. The lipid oxidation degree of beef decreased following SM-ES treatment. SM-ES treatment extended the shelf-life of beef for more than 6 days compared with refrigeration while prevented its crystallizing.


Assuntos
Metabolismo dos Lipídeos , Refrigeração , Animais , Bovinos , Congelamento , Campos Magnéticos , Oxirredução
5.
Food Chem ; 371: 131054, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34555708

RESUMO

Freezing technology is important for storage of animal products such as surimi. However, mechanical damage caused by ice crystals would lead to quality deterioration. This study aims to investigate the protective effect of antifreeze peptides (AFPs) on the quality of surimi during freezing storage and its possible mechanism. We found that AFPs exhibited a strong inhibition of ice crystal recrystallization, and the molecular weight ranged from 180 to 3000 Da. AFPs can prevent the degeneration of myofibrillar protein by reducing the loss of Ca2+-ATPase activity, slowing oxidation of sulfhydryl groups to disulfide bonds, and maintaining surface hydrophobicity and solubility of myofibrillar protein. Moreover, AFPs can reduce the influence of freezing stress on water mobility, thereby protecting the surimi from losing immobilized water and bound water during frozen storage. These findings indicate that AFPs could potentially serve as a food ingredient with antifreeze functional for the storage of surimi products.


Assuntos
Proteínas Anticongelantes , Crioprotetores , Animais , Congelamento , Gelo , Produtos da Carne , Oxirredução , Água
6.
Sci Total Environ ; 802: 149870, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34525703

RESUMO

Climate warming is expected to cause greater increases in nocturnal temperatures than daytime temperatures, thereby altering freeze-thaw cycles. Although the importance of freeze-thaw cycles in regulating soil aggregate stability and nutrient availability has attracted increasing attention, little is known about how winter nocturnal warming modulates freeze-thaw frequency, soil aggregate distribution, or the contents and mineralization of soil organic carbon (SOC) and total nitrogen (TN) in paddy fields. The nocturnal soil temperature in the upper 0-2 cm layer in a paddy field was elevated by approximately 2 °C using a passive nocturnal warming method during winter. An anaerobic experiment with a first-order reaction model was conducted to measure the C decomposition (C0) and N mineralization (N0) potentials in bulk soil and four soil aggregate fractions. Winter nocturnal warming significantly decreased freeze-thaw frequency and affected soil aggregate distribution and SOC and TN contents in <0.25 mm aggregate. Both SOC and TN fractions were significantly increased in the 0.25-1 mm aggregate but decreased in the >2 mm aggregate due to winter nocturnal warming. Winter nocturnal warming did not affect C0, N0, C0/SOC, and N0/TN in bulk soil. However, it decreased C0 and C0/SOC in all aggregates except the 0.25-1 mm aggregate, and increased N0 and N0/TN in all aggregates except the >2 mm aggregate. In the nocturnal warming treatment, the highest C0 and N0 values were found in the <0.25 mm aggregate, but only the N0 in the <0.25 mm aggregate was significantly larger than that in the other three soil aggregates. Our study indicated that winter nocturnal warming would reduce the freeze-thaw frequency and change C and N distributions in soil aggregates, resulting in increased soil N availability in the subsequent rice growth season.


Assuntos
Carbono , Solo , Congelamento , Nitrogênio/análise , Estações do Ano
7.
Sci Total Environ ; 807(Pt 1): 150746, 2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-34619186

RESUMO

The moisture content of farmland soils is closely related to the farmland soil environment. Although biochar has been widely studied for farmland soil amelioration in tropical and temperate farmland soils, its application in areas of seasonally frozen soil is rare. In this study, field experiments were conducted to explore the effect of biochar on soil temperature and soil liquid moisture content in seasonally frozen soils and its corresponding mechanism. Biochar was applied to the soil at different rates (3 kg·m-2, 6 kg·m-2, 9 kg·m-2, and 12 kg·m-2) in autumn and spring. Daily monitoring data from the 20 cm soil-layer recorded for one year from the biochar application date were analyzed. The approximate entropy was introduced to explore the complex changes in soil temperature and soil liquid moisture content under biochar application in seasonally frozen soils. According to the calculation of approximate entropy, the application of biochar increased the complexity for most treatments. In the case of ignoring the heterogeneity of snowfall and uneven land tillage to the soil, we infer that this change was caused by changes in properties of the biochar due to the freeze-thaw cycle. The treatment under mixed biochar application in spring and autumn of 9 kg·m-2 had the smallest change in water and heat complexity. And the approximate entropy of this treatment is the smallest. Moreover, in the freezing period, the soil liquid moisture content is positively correlated with the biochar amount applied and negatively correlated with the biochar and soil mixing time. In the melting period, the opposite correlations occur. The changes in soil moisture conditions caused by freezing and thawing restrict the affinity of biochar for water. Therefore, the effect of biochar addition on the soil liquid moisture content varies among different freezing and thawing periods.


Assuntos
Solo , Água , Carvão Vegetal , Fazendas , Congelamento
8.
Food Chem ; 373(Pt A): 131449, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34715631

RESUMO

This study investigated the effect of pulsed electric field assisted freezing treatment on the freezing characteristics of rice flour gel under output voltages varying from 0 to 25 kV. The results indicated that by applying a pulsed electric field, the phase change time decreased. Scanning electron microscopy images indicated that pulsed electric field treatment led to the formation of rounder and smaller ice crystals. For further understanding and quantifying the interaction between rice flour gel and a pulsed electric field, the relative permittivity of rice flour gel with and without the addition of salt was measured between 100 and 3100 kHz and -20 and 20 °C. Relative permittivity increased with decreasing frequency or increasing temperature, and sharp variation was observed during the phase transition period. In addition, salt was proved to be an effective additive for increasing relative permittivity.


Assuntos
Farinha , Oryza , Eletricidade , Congelamento , Temperatura
9.
Colloids Surf B Biointerfaces ; 210: 112252, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34902712

RESUMO

Ice accretion on surfaces can cause serious damages and economic losses in industries and civilian facilities. Antifreeze proteins (AFPs) as evolutionary adaptation products of organisms to cold climates, provide solutions for alleviating icing problems. In this work, a chimeric protein Mfp-AFP was rationally designed combining mussel-inspired adhesive domain with Tenebrio molitor-derived antifreeze protein domain. Expectedly, the multifunctional Mfp-AFP can lower the freezing point of water and inhibit ice recrystallization. The chimeric protein could also readily modify diverse solid surfaces due to the adhesive domain containing Dopa, and resist frosting and delay ice formation due to the beetle-derived antifreeze fragment. Moreover, Mfp-AFP coatings display excellent biocompatibility proved by cytocompatibility and hemolysis assays. Here, the designed multifunctional protein coatings provide an alternative strategy for fabricating anti-icing surfaces.


Assuntos
Besouros , Tenebrio , Animais , Proteínas Anticongelantes/genética , Congelamento , Proteínas Recombinantes de Fusão , Água
10.
Food Chem ; 374: 131737, 2022 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-34920408

RESUMO

The effects of different liquid nitrogen freezing (LNF) temperatures (-35, -55, -75, -95, and -115 °C) on the freezing rate, physicochemical properties, and microstructure of golden pompano (Trachinotus ovatus) were evaluated in the present study. The results showed that the total freezing time of golden pompano was significantly shortened using LNF (P < 0.05). Compared with other freezing methods, the cooking loss and L* values (lightness) of -95 °C LNF golden pompano were significantly lower, the false-colour image was much redder and brighter, the loss and mobility of water in fish muscle were inhibited, the water holding capacity and hardness were higher, and the muscle microstructure was comparatively intact. Therefore, -95 °C LNF effectively shortened the freezing time and improved the muscle qualities of frozen golden pompano.


Assuntos
Peixes , Músculos , Animais , Congelamento , Nitrogênio , Temperatura
11.
Methods Mol Biol ; 2257: 311-347, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34432286

RESUMO

The critical role microRNAs play in modulating global functions is emerging, both in the maintenance of homeostatic mechanisms and in the adaptation to diverse environmental stresses. When stressed, cells must divert metabolic requirements toward immediate survival and eventual recovery and the unique features of miRNAs, such as their relatively ATP-inexpensive biogenesis costs, and the quick and reversible nature of their action, renders them excellent "master controllers" for rapid responses. Many animal survival strategies for dealing with extreme environmental pressures involve prolonged retreats into states of suspended animation to extend the time that they can survive on their limited internal fuel reserves until conditions improve. The ability to retreat into such hypometabolic states is only possible by coupling the global suppression of nonessential energy-expensive functions with an activation of prosurvival networks, a process in which miRNAs are now known to play a major role. In this chapter, we discuss the activation, expression, biogenesis, and unique attributes of miRNA regulation required to facilitate profound metabolic rate depression and implement stress-specific metabolic adaptations. We examine the role of miRNA in strategies of biochemical adaptation including mammalian hibernation, freeze tolerance, freeze avoidance, anoxia and hypoxia survival, estivation, and dehydration tolerance. By comparing these seemingly different adaptive programs in traditional and exotic animal models, we highlight both unique and conserved miRNA-meditated mechanisms for survival. Additional topics discussed include transcription factor networks, temperature dependent miRNA-targeting, and novel species-specific and stress-specific miRNAs.


Assuntos
MicroRNAs/genética , Aclimatação , Adaptação Fisiológica , Animais , Congelamento , Hibernação , Hipóxia
12.
Theriogenology ; 179: 245-253, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34922135

RESUMO

Glycerol is widely used as a cryoprotectant to protect the sperm from freezing damage during cryopreservation. However, glycerol at a high concentration has toxic effects on the sperm. Therefore, we explored the effects of partially replacing glycerol with cholesterol-loaded cyclodextrin (CLC) in a cryoprotectant on protamine deficiency, in vitro capacitation, and fertilization ability of freeze-thawed Yanbian Yellow cattle sperm. We used fresh semen, control (6% glycerol), and four treatment-I, II, III, and IV (3% glycerol + 0, 0.75, 1.5, and 3 mg/mL CLC, respectively)-groups. Computer-assisted semen analysis; JC-1, CMA3, and FluoZin-3-AM staining; flow cytometry; and IVF were conducted. Replacing a portion of glycerol with 1.5 mg/mL CLC significantly improved sperm motility, viability, plasma membrane integrity, acrosome integrity, and membrane lipid disorders, mitochondrial membrane potential (MMP), capacitation, and fertilization ability (P < 0.05) compared with the control. Additionally, in group I and III, the protamine deficiency were significantly lower (P < 0.05) than in the control group. It was found that 6% glycerol has a higher degree of damage to sperm DNA integrity than 3% glycerol. Overall, this study revealed that partial replacement of glycerol with CLC can be used as a novel cryoprotection method to reduce the toxicity of glycerol and improve the quality of thawed Yanbian Yellow cattle sperm.


Assuntos
Ciclodextrinas , Preservação do Sêmen , Animais , Bovinos , Colesterol , Criopreservação/veterinária , Crioprotetores/farmacologia , Ciclodextrinas/farmacologia , Fertilização , Congelamento , Glicerol , Masculino , Protaminas/farmacologia , Preservação do Sêmen/veterinária , Motilidade Espermática , Espermatozoides
13.
Water Sci Technol ; 84(12): 3769-3779, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34928842

RESUMO

As the cornerstone of normal operation for Sponge City, the service performance of permeable pavement is directly related to the utilization rate of precipitation resources. However, the pore filling state (air, water and ice) of permeable pavement in Sponge City is easily affected by the service environment, especially low temperature. Thus, in the study, the influence of pore filling states and phase change processes on the service performance for permeable pavement were studied based on the models established on specimen section. Details of pore water phase change were visually displayed and described, and the strength variation of Marshall specimens after freeze-thaw cycle experiment also proved the rationality of simulation. Results show that the pore filling states in permeable pavement have different effects on the temperature field, and the influence of pore air on the temperature distribution for permeable pavement is greater than that of pore water (ice). In particular, weak positions between different pores are more susceptible to freezing stress, leading to stress concentration. Simulation results were also verified by macro experiments. Furthermore, the sustainable service performance of permeable pavement in Sponge City was inevitably affected. Therefore, the study results have certain significance for the development of permeable pavement in freezing and thawing regions, and are conducive to the wider application of Sponge City.


Assuntos
Água , Congelamento
14.
Medicina (Kaunas) ; 57(12)2021 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-34946288

RESUMO

Background and Objectives: As an mRNA-based vaccine, the Pfizer-BioNTech COVID-19 vaccine has stringent cold storage requirements to preserve functionality of the mRNA active ingredient. To this end, lipid components of the vaccine formulation play an important role in stabilizing and protecting the mRNA molecule for long-term storage. The purpose of the current study was to measure molecular-level dynamics as a function of temperature in the Pfizer-BioNTech COVID-19 vaccine to gain microscopic insight into its thermal stability. Materials and Methods: We used quasielastic and inelastic neutron scattering to probe (1) the vaccine extracted from the manufacturer-supplied vials and (2) unperturbed vaccine in the original manufacturer-supplied vials. The latter measurement was possible due to the high penetrative power of neutrons. Results: Upon warming from the low-temperature frozen state, the vaccine in its original form exhibits two-step melting, indicative of a two-phase morphology. Once the melting is completed (above 0 °C), vaccine re-freezing cannot restore its original two-phase state. This observation is corroborated by the changes in the molecular vibrational spectra. The molecular-level mobility measured in the resulting single-phase state of the re-frozen vaccine greatly exceeds the mobility measured in the original vaccine. Conclusions: Even a brief melting (above 0 °C) leads to an irreversible alteration of the two-phase morphology of the original vaccine formulation. Re-freezing of the vaccine results in a one-phase morphology with much increased molecular-level mobility compared to that in the original vaccine, suggesting irreversible deterioration of the vaccine's in-storage stability. Neutron scattering can be used to distinguish between the vibrational spectra characteristic of the original and deteriorated vaccines contained in the unperturbed original manufacturer-supplied vials.


Assuntos
COVID-19 , Vacinas contra COVID-19 , Congelamento , Humanos , SARS-CoV-2
15.
Artigo em Inglês | MEDLINE | ID: mdl-34948801

RESUMO

This study examines the evolution law of the coal temperature field under low-temperature freezing conditions. The temperature inside coal samples with different water contents was measured in real-time at several measurement points in different locations inside the sample under the condition of low-temperature medium (liquid nitrogen) freezing. The temperature change curve was then used to analyse the laws of temperature propagation and the movement of the freezing front of the coal, which revealed the mechanism of internal water migration in the coal under low-temperature freezing conditions. The results indicate that the greater the water content of the coal sample, the greater the temperature propagation rate. The reasons for this are the phase change of ice and water inside the coal during the freezing process; the increase in the contact area of the ice and coal matrix caused by the volume expansion; and the joint action of the two. The process of the movement of the freezing front is due to the greater adsorption force of the ice lens than that of the coal matrix. Thus, the water molecules adsorbed in the unfrozen area of the coal matrix migrate towards the freezing front and form a new ice lens. Considering the temperature gradient and water content of the coal samples, Darcy's permeation equation and water migration equation for the inside of the coal under freezing conditions were derived, and the segregation potential and matrix potential were analysed. The obtained theoretical and experimental results were found to be consistent. The higher the water content of the coal samples, the smaller the matrix potential for the hindrance of water migration. Furthermore, the larger the temperature gradient, the larger the segregation potential, and the faster the water migration rate.


Assuntos
Carvão Mineral , Água , Temperatura Baixa , Congelamento , Temperatura
16.
Cells ; 10(12)2021 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-34943919

RESUMO

Cyanobacteria from the genus Arthrospira/Limnospira are considered haloalkalotolerant organisms with optimal growth temperatures around 35 °C. They are most abundant in soda lakes in tropical and subtropical regions. Here, we report the comprehensive genome-based characterisation and physiological investigation of the new strain O9.13F that was isolated in a temperate climate zone from the winter freezing Solenoye Lake in Western Siberia. Based on genomic analyses, the Siberian strain belongs to the Arthrospira/Limnospira genus. The described strain O9.13F showed the highest relative growth index upon cultivation at 20 °C, lower than the temperature 35 °C reported as optimal for the Arthrospira/Limnospira strains. We assessed the composition of fatty acids, proteins and photosynthetic pigments in the biomass of strain O9.13F grown at different temperatures, showing its potential suitability for cultivation in a temperate climate zone. We observed a decrease of gamma-linolenic acid favouring palmitic acid in the case of strain O9.13F compared to tropical strains. Comparative genomics showed no unique genes had been found for the Siberian strain related to its tolerance to low temperatures. In addition, this strain does not possess a different set of genes associated with the salinity stress response from those typically found in tropical strains. We confirmed the absence of plasmids and functional prophage sequences. The genome consists of a 4.94 Mbp with a GC% of 44.47% and 5355 encoded proteins. The Arthrospira/Limnospira strain O9.13F presented in this work is the first representative of a new clade III based on the 16S rRNA gene, for which a genomic sequence is available in public databases (PKGD00000000).


Assuntos
Álcalis/química , Congelamento , Genômica , Lagos/microbiologia , Estações do Ano , Spirulina/genética , Spirulina/fisiologia , Aclimatação , Carotenoides/metabolismo , Clorofila/metabolismo , Ácidos Graxos/metabolismo , Genoma , Fenótipo , Filogenia , Salinidade , Sibéria , Spirulina/isolamento & purificação , Spirulina/ultraestrutura , Estresse Fisiológico
17.
Sensors (Basel) ; 21(24)2021 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-34960496

RESUMO

The development and improvement of monitoring and process control systems is one of the important ways of advancing laser metal deposition (LMD). The control of hydrodynamic, heat and mass transfer processes in LMD is extremely important, since these processes directly affect the crystallization of the melt and, accordingly, the microstructural properties and the overall quality of the synthesized part. In this article, the data of coaxial video monitoring of the LMD process were used to assess the features of melt dynamics. The obtained images were used to calculate the time dependences of the characteristics of the melt pool (MP) (temperature, width, length and area), which were further processed using the short-time correlation (STC) method. This approach made it possible to reveal local features of the joint behavior of the MP characteristics, and to analyze the nature of the melt dynamics. It was found that the behavior of the melt in the LMD is characterized by the presence of many time periods (patterns), during which it retains a certain ordered character. The features of behavior that are important from the point of view of process control systems design are noted. The approach used for the analysis of melt dynamics based on STC distributions of MP characteristics, as well as the method for determining the moments of pattern termination through the calculation of the correlation power, can be used in processing the results of online LMD diagnostics, as well as in process control systems.


Assuntos
Temperatura Alta , Lasers , Cristalização , Congelamento , Temperatura
18.
Immunohematology ; 37(4): 157-159, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34964316

RESUMO

Rare red blood cells (RBCs) can be used to resolve reactivity in antibody identification or compatibility testing. Because these RBCs are usually not readily available, when identified in donors or patients, a quick and easy method for long-term storage is needed. By freezing in liquid nitrogen, injury to the RBCs is prevented, and rendering them usable for testing takes only a few washes.Rare red blood cells (RBCs) can be used to resolve reactivity in antibody identification or compatibility testing. Because these RBCs are usually not readily available, when identified in donors or patients, a quick and easy method for long-term storage is needed. By freezing in liquid nitrogen, injury to the RBCs is prevented, and rendering them usable for testing takes only a few washes.


Assuntos
Preservação de Sangue , Criopreservação , Eritrócitos , Congelamento , Humanos , Nitrogênio
19.
Zhonghua Nan Ke Xue ; 27(5): 416-420, 2021 May.
Artigo em Chinês | MEDLINE | ID: mdl-34914316

RESUMO

Objective: To investigate the factors causing bacterial contamination of donor semen during cryopreservation. METHODS: Based on the WHO Laboratory Manual for the Examination and Processing of Human Semen (5th ed), we diluted donor semen samples with sperm cryopreservation medium in a 1∶1 (v/v) ratio. Before the experiment, we cultured bacteria in the sperm cup, sperm cryopreservation medium and Columbia blood a-gar medium to ensure sterile growth. We also conducted bacterial culture of 3,112 semen samples before and after freezing and, according to the number of bacterial colonies (NBC), divided them into a normal group (NBC before freezing <104 cfu/ml and >NBC after freezing) and an abnormal group (NBC before freezing ≥104 cfu/ml and ≥ NBC after freezing, or NBC before freezing < NBC after freezing), followed by bacterial species identification of the suspected colonies. RESULTS: Of the 3 112 donor semen samples, 2 458 (78.98%) were included in the normal, and the other 654 (21.02%) in the abnormal group (263 ï¼»8.45%ï¼½ with NBC before freezing ≥104 cfu/ml and ≥ NBC after freezing, and 391 ï¼»12.56%ï¼½ with NBC before freezing < NBC after freezing). In the suspected colonies, 217 (6.97%) strains of bacteria were isolated and identified, mainly including Staphylococcus epidermidis (23.96%), Staphylococcus haemolyticus (16.59%), Corynebacterium minutissimum (11.52%), Staphylococcus aureus (7.37%), and Enterococcus faecalis (5.99%). CONCLUSIONS: The bacteria detected in the donor semen mainly included Staphylococcus epidermidis, Staphylococcus haemolyticus, Corynebacterium minutissimum, Staphylococcus aureus and Enterococcus faecalis. Many factors may cause bacterial contamination of donor semen during cryopreservation, which can be reduced by employing sterile, clean and dry materials, appropriate semen preservation methods, normalized experimental environment, and standard operating procedures.


Assuntos
Líquidos Corporais , Preservação do Sêmen , Criopreservação , Congelamento , Humanos , Masculino , Sêmen
20.
Int J Pharm Compd ; 25(6): 446-462, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34807839

RESUMO

The objective of this review was to collect information and results about the method of the microwave freeze-thaw treatment of injectable drugs and whether the method can support the development of Centralized Intravenous Admixtures Services. A systematic review of the scientific literature about injectable drug stability studies was performed. The data are presented in a table, which describes the name of the drug, producer, final concentration, temperature and time of freezing storage, type of microwave oven, thawing power, method of dosage, and the results after treatment or final long-term storage at 5°C ± 3°C. From 1980 to 2021, 60 drugs were studied by the microwave freeze-thaw treatment, and the results were presented in 49 publications. Forty papers were presented by 8 teams (2 to 18 by team). The temperatures of freezing storage varied from -70°C to -10°C, the time storage from 4 hours to 12 months, and the thaw from low to full power. Drug concentrations were mainly determined by high-performance liquid chromatography. Most of the 59 drugs were stable during and after treatment. Only three teams tested the long-term stability after the microwave freeze-thaw treatment, the first for ganciclovir after 7 days, the second for ceftizoxime after 30 days, and the third for 20 drugs after 11 to 70 days. This review can help Centralized Intravenous Additive Services take charge of the productions of ready-to-use injectable drugs.


Assuntos
Micro-Ondas , Preparações Farmacêuticas , Composição de Medicamentos , Estabilidade de Medicamentos , Congelamento
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