Search results for "cryopreservation"

Lyophilization of lepidopteran midguts: a preserving method for Bacillus thuringiensis toxin binding studies

2004

Binding assays with brush border membrane vesicles (BBMV) from insect midguts are commonly used in the study of the interactions between Bacillus thuringiensis Cry toxins and their receptors. Collaboration between laboratories often require that frozen insect samples are sent in dry ice. Because of customs restrictions and delays, sample thawing is always a risk and often the biological material becomes ruined during shipping. We have tested lyophilization as an alternative method for preserving insect midguts for binding studies with B. thuringiensis Cry toxins. For this purpose, BBMV were prepared from both frozen and lyophilized midguts from three lepidopteran species: Spodoptera exigua,…

Why do results conflict regarding the prognostic value of the methylation status in colon cancers? The role of the preservation method.

2012

Abstract Background In colorectal carcinoma, extensive gene promoter hypermethylation is called the CpG island methylator phenotype (CIMP). Explaining why studies on CIMP and survival yield conflicting results is essential. Most experiments to measure DNA methylation rely on the sodium bisulfite conversion of unmethylated cytosines into uracils. No study has evaluated the performance of bisulfite conversion and methylation levels from matched cryo-preserved and Formalin-Fixed Paraffin Embedded (FFPE) samples using pyrosequencing. Methods Couples of matched cryo-preserved and FFPE samples from 40 colon adenocarcinomas were analyzed. Rates of bisulfite conversion and levels of methylation of …

Cryopreservation of Escherichia coli K12TG1: Protection from the damaging effects of supercooling by freezing

2015

Injuries in living cells caused by water freezing during a freeze-thaw process have been extensively reported. In particular, intracellular water freezing has long been incriminated in cell death caused by a high cooling rate, but this supposition could not always be demonstrated. This work aims to discriminate the role of water freezing, dehydration and cold-induced injuries in cellular damage occuring during cryopreservation. For this purpose, Escherichia coli K12TG1 suspensions were maintained in a supercooled or frozen state at -20°C for times ranging from 10 min to 5 h. The supercooled state was maintained for a long period at -20°C by applying a non-injurious isostatic pressure (P<40 …

Present status of the application of cryopreserved hepatocytes in the evaluation of xenobiotics: consensus of an international expert panel.

1999

Successful cryopreservation of freshly isolated hepatocytes would significantly decrease the need for freshly-procured livers for the preparation of hepatocytes for experimentation. Hepatocytes can be prepared, cryopreserved, and used for experimentation as needed at different times after isolation. Cryopreservation is especially important for research with human hepatocytes because of the limited availability of fresh human livers. Based on the cumulative experience of this international expert panel, a consensus was reached on the various aspects of hepatocyte cryopreservation, including cryopreservation and thawingprocedures and applications of the cryopreserved hepatocytes. Key to succe…

PEMBEKUAN SEMEN LELE DUMBO (Clarias Gariepinus BURCHELL 1822) SEBAGAI MODEL KRIOPRESERVASI SEMEN IKAN

2010

&lt;p&gt;&lt;em&gt;Effect of four types of diluents&lt;/em&gt;&lt;em&gt;s&lt;/em&gt;&lt;em&gt; and four concentration of DMSO (5%, 10%, 15% and 20%) against the motility of African catfish sperm were evaluated after storage at freezing temperatures. &lt;/em&gt;&lt;em&gt;The steps in preparation the 16 treatments combination of the diluents&lt;/em&gt;&lt;em&gt; &lt;/em&gt;&lt;em&gt;are &lt;/em&gt;&lt;em&gt;preparation of diluents, mixing &lt;/em&gt;&lt;em&gt;diluents &lt;/em&gt;&lt;em&gt;with DMSO, packing &lt;/em&gt;&lt;em&gt;of semen &lt;/em&gt;&lt;em&gt;in&lt;/em&gt;&lt;em&gt;to&lt;/em&gt;&lt;em&gt; 0.3-ml straw, equilibration of &lt;/em&gt;&lt;em&gt;semen &lt;/em&gt;&lt;em&gt;at 4 °C for…

CRYOPRESERVATION OF CITRUS GERMPLASM: CONSIDERATIONS ON A CASE-STUDY

2010

Fertility and breast cancer: A literature review of counseling, preservation options and outcomes.

2021

Fertility preservation is an important issue in breast cancer patients undergoing oncological treatment. Fertility counseling is a crucial need given the physical and psychological stress experienced by patients. Cryopreservation of mature oocytes is currently the standard fertility-preserving procedure. Other options such as ovarian tissue preservation or gonadal protection during chemotherapy are still experimental, but have proven effectiveness. Prompt referral to a fertility unit is highly recommended in order to ensure quality of care. In this article, we focus on the different strategies to preserve fertility in breast cancer patients, assessing also the safety of pregnancy and breast…

Cell inactivation and membrane damage after long-term treatments at sub-zero temperature in the supercooled and frozen states.

2008

The survival of cells subjected to cooling at sub-zero temperature is of paramount concern in cryobiology. The susceptibility of cells to cryopreservation processes, especially freeze-thawing, stimulated considerable interest in better understanding the mechanisms leading to cell injury and inactivation. In this study, we assessed the viability of cells subjected to cold stress, through long-term supercooling experiments, versus freeze-thawing stress. The viability of Escherichia coli, Saccharomyces cerevisiae, and leukemia cells were assessed over time. Supercooled conditions were maintained for 71 days at -10 degrees C, and for 4 h at -15 degrees C, and -20 degrees C, without additives or…

Cui prodest servāre? Due ipotesi di destinazione per gli embrioni crioconservati

2022

The essay analyses the general ban for the donation of embryos placed into cryopreservation, stated by the Italian legislation n. 40/2004. Such a prevision causes a sine die conservation not only for embryos suitable for implantation, but also for those affected by genetic defects or diseases. The essay points out that donating both types of embryos, respectively, to adoption or to scientific fertility research preserves the dignity of the cells in storage, as a will supported by the consent of both gametes’ providers to the ultimate scope of solidarity.

Zygotic and nucellar embryo survival following dehydration and cryopreservation of citrus intact seeds.

2004

A cryopreservation procedure by dehydration and direct immersion in liquid nitrogen was developed for seeds of four polyembryonic Citrus species, and the sexual or nucellar origin of the recovered seedlings was investigated. Seeds of three species could be desiccated in a sterile air flow to 16 percent (C. sinensis) or 10 percent (C. aurantium and C. limon) moisture content with a negligible reduction in germination levels. Differently, the germinability of C. deliciosa seeds dropped to 50 percent after drying to 15 percent moisture content. Following dehydration treatments, a reduction in the average number of seedlings per germinated seed was always observed. However, all four species ben…