Your questions
Vos questions
These are the questions most often asked of DMC. Should you have any other queries, let contact us! What are the underlying principles of cryobiology? What types of samples can one preserve in liquid nitrogen? What reasons are there to preserve in liquid nitrogen and what is the maximum preservation? What contraints of use are associated with liquid nitrogen? What safety and suveillance arrangements are made for storage containers? How can one provide a simplified method of managing thousands of samples? How is the freezing of samples carried out and how long does it take? Will samples be lost in the event of a power failure? Is it possible to preserve samples in nitrogen when in gas form? What methods are used to supply containers with liquid nitrogen ? In the event of losing a sample in the bottom of container, is it possible to recover it ? What are the underlying principles of cryobiology? First appearing in the 18th century, cryobiology has its origins in the Greek Kryos (cold) and biologos (life-science). This science, which is at the meeting-point of physics and biology, studies the behaviour of living beings when exposed to very low temperatures. The earliest attempts at freezing spermatozoids were carried out using snow, the only available source of coldness in those days. Dry ice, and later liquid nitrogen, made it possible to reach today's preservation temperatures of -79°C and -195°C respectively. What types of samples can one preserve in liquid nitrogen? Nowadays, current techniques make it possible to preserve at very low temperatures an appreciable number of cells, tissues, and very small human organs;such as : vaccines,plans, cellular suspensions, red globules, platelets, spermatozoids, human embryos, cell cultures, bone-marrow, blood stem cells, cord blood, bones, osteo-articular transplants, cartilage, tendons, ligaments, skin, cardiac valves, vessels, parathyroids... However, real difficulties remain in the case of multicellular organisms (heart, kidneys...). What reasons are there to preserve in liquid nitrogen and what is the maximum preservation? For very-long term preservation, cryo-preservation (storage in liquid nitrogen at -196°C) is the only method in existence.In fact, it is reckoned that at below -130°, all cell-divisions, as well as metabolic processes, are halted. In principle, therefore, samples can therefore be stored, without any alteration or change, and with reduced upkeep, for an unlimited period of time. What contraints of use are associated with liquid nitrogen? Nitrogen exists in two forms : gas (nitrogen air component is 78%, oxygen 21%, rare gases 1%) and liquid (temperature -196°C). One liter od liquid nitrogen corresponds to 691 liters of nitrogen gas. Nitrogen is hazardous in both states. It gaseous state brings the risk of anoxia (insufficient oxygen in the air) whereas in its liquid form, it can be teh cause of serious cryogenic burns. In addition, containers holding liquid nitrogen must meet the requirements of applicable international rules on the shipping of hazardous substances by surface, air or rail. Depending on the sizes and characteristics of samples, they are stored in straws, cryotubes or bags of various capacities. The storage items are subsequently placed in storage container facilities appropriate for their size. What safety and suveillance arrangements are made for storage containers? Containers can be fitted with devices for controlling and recording temperature and level. Fitted with visual and audible alarms, these devices can be remote-controlled by a telemonitoring arrangement. How can one provide a simplified method of managing thousands of samples? Since cryo-preservation is an expanding science, the number of samples to be kept is constantly increasing (the RCB1001 can accommodate over 920.000 straws!). With this in mind, we have developed COOLBASE, user-frienddly software for management of stored products, making it possible to define, display, store away and retrieve all your samples with complete traceability and safety of use. How is the freezing of samples carried out and how long does it take? Freezing of samples is carried out by using thresholds following a previously-set procedure, depending on their biological characteristics and on the cryo-protector being used. The duration of the freezing cycle is also fixed in accordance with the set procedure. Will samples be lost in the event of a power failure? All our containers are built on the principle of super-insulation under vacuum, which gives them maximum static endurance. Consequently, even in the event of a breakdown, liquid nitrogen's evaporation rate remains low and samples are held at at temperature that will note jeopardise their survival. In the event of a breakdown, it is also possible to refill containers maunually with the help of a bowpipe that draws off liquid nitrogen from the main tank, to which it is connected up. Is it possible to preserve samples in nitrogen when in gas form? Below –130°C, all enzymatic activity is completely halted, and samples can theoretcally be stored for an unlimited period. During cryo-preservation in gas form, the container temperature above the samples is around -160°C and preservation is hence perfectly possible. In addition, the fact of cryo-preserving in gas form does have certain advantages compared with cryo-preservation in liquid form (see the heading "Latest news".) What methods are used to supply containers with liquid nitrogen ? Several solutions are on offer to the user of liquid nitrogen, depending on the number of containers to be supplied. For small quantities , it is possible to store liquid nitrogen in auto-pressurised containers of various sizes. When we are dealing with larger quantities, it is better to connect the containers up to several thousand litres of liquid nitrogen in bulk, through a super-insulated line unde vacuum. In the event of losing a sample in the bottom of container, is it possible to recover it ? In the event of losing a sample in the bottom of the container floor, it is possible to recover it with the help of specially-adapted twezers. However, extreme vigilance is called for, and do not forget that cryobiological gloves have been designed to resist coldness from gas, not for plunging into liquid nitrogen.
- Legal notice
- |
- Site map
- |
- © Copyright DMC & CRYOPAL 2008
