Laminar flow cabinet

All laboratory operations are carried out in laminar flow cabinets in rooms in which filtered air is maintained at a slight positive pressure relative to their outer environment. Operators wear sterilized clothing and work aseptically. Antibiotic fermentations are, of strict necessity, pure culture aseptic processes, without con-tamirrating orgarrisms. 

Basic equipment for plant culture media preparation and sterilization, controlled growth chamber, microscope, stereomicroscope and inverted microscope equipped with a photocamera, laminar flow cabinet. 

Detach the head from the pump, close the stopcock, and lift the whole unit into the laminar flow cabinet. 

Because of the sensitivity of PCR assays, it is most important to minimise the potential danger of cross-contamination. Ideally, PCR laboratories should consist of two separate rooms, each containing their own equipment (e.g., pipetors). One room should be dedicated to the setting up of RT reactions and PCR assays only. Both laboratories should use aerosol-resistant tips to prevent carry-over of sample within the barrel of the pipet. Post-PCR tubes should never be opened in the room used to set up PCRs as this is probably the most potent source for potential contamination. A laminar-flow cabinet, particularly one designed for PCR, should be considered a requirement for a PCR room in situations where a large number of samples will be processed. 

Gel pieces can be cut and processed in laminar-flow cabinets, although this is usually not necessary if sensible precautions are taken. 

All the procedures carried out on a small scale are labor-intensive and require skilled operators. Manipulation of the cultures is carried out in laminar-flow cabinets, to maintain asepsis. During this stage of cell propagation/inoculum development, activities are carried out by direct operator manipulation, so that the process is considered to be open . 

The manipulation of this bioreactor is generally performed in a laminar-flow cabinet, and is thus an open and risky operation. This is probably a characteristic that differentiates this bioreactor type from the other homogeneous bioreactors, where reliability of all seals and connections can be ensured through the use of direct steam. Also, the large number of connections using flexible tubing makes the operation of this type of bioreactor more complicated than that of other bioreactors of the same class. Currently, the performance and application potential of these bioreactors are under evaluation by the biotechnological community. 

Always work in a laminar flow cabinet ( 9.4.2) or close to a bunsen flame. 

Laminar flow cabinets serve two purposes to protect the samples and to protect the worker and the environment. For most tissue culture applications sample protection is sufficient, but increasingly often we are becoming aware of hazards associated with biological samples and the cabinet to choose combines both aspects of protection. Such are the vertical laminar flow cabinets available, for example, from Flow Laboratories (Gelaire) or M.D.H. (Appendix 3). 

The use of a laminar flow system would appear to make it impossible for bacteria to pass from the worker to the culture and in principle they provide ideal protection for both cultures and workers. However, the very act of putting the hands into the air stream disturbs the laminar flow and causes eddies. For this reason laminar flow cabinets should only be used in addition to standard aseptic technique although it is unnecessary to work near a bunsen flame. 

We routinely use a (dedicated) laminar flow cabinet to prepare the Percoll gradients and perform subsequent manipulations. It is important to avoid activating the cells during these procedures. 

Change from a mobile to a static (plumbed-in) system with connection to steam for in situ sterilization, manipulation being carried out in the open laboratory (not a laminar flow cabinet), more sophisticated temperature control and additional vessels for medium holding and culture harvesting. 

Aseptic manipulations must be carried out in the grade A air of a laminar flow cabinet. Speed, accuracy and economy of movement are essential features of good aseptic technique. It is therefore essential that workers are well trained and motivated and familiar with the task in hand. Observation and microbiological monitoring of the operator and of the environment are very important. Air quality is measured using settle plates or slit samplers, work surfaces by taking swabs or by use of contact plates (Chapter 20). 

Horizontal laminar flow cabinets used for product protection, for example, in the pharmaceutical industry, exhaust directly into the face of the operator. This equipment must never be used as a biological (microbiological) safety cabinet. 

A pre-PCR area, where reaction mixes are prepared. This area can be a positive-pressure vertical laminar flow cabinet equipped with an ultraviolet (UV) lamp that is switched on for 20 min after use to destroy any possible contaminating DNA. 

Positive-pressure laminar flow cabinet equipped with a UV lamp. 

Negative-pressure laminar flow cabinet (type fume hood) equipped with an HEPA filter before the air exhaust, and with a UV lamp. 

Turn on UV lamp of laminar flow cabinet for 20 min, to allow for destruction of any contaminating cDNA. 

Physical separation of animals by species is generally recommended to prevent interspecies disease transmission and to reduce anxiety owing to interspecies conflict. In some situations it might be appropriate to house different species of rodents in the same room, such as when they are to be used for tests of the same test article and have a similar health status or when special containment is provided within rooms (e.g., laminar flow cabinets or filtered or microisolation cages). It is not uncommon for animals from one supplier to harbor microbial agents not found in animals of the same species from another supplier, therefore intraspecies separation is advisable when animals obtained from multiple sources differ in microbiological status (21). 

Spray the suspension onto one of the TLC plates and incubate at 25 C for 2dm an assay tray with moist cotton wool to ensure a moist atmosphere. This spraying should be performed in a laminar flow cabinet. 

In manufacturing processes, the use of closed systems to minimize contaminations should be pursued. In such processes, where materials sensitive to microbial contamination may contact contaminated air, appropriate measures shall be taken to prevent the contamination (over pressure, laminar flow cabinets, etc.. 

It is worthwhile to check the plates after several hours for the formation of a water droplet at the inoculum site. If this happens, the plate should be allowed to dry in the laminar flow cabinet and the incubation then continued. Droplet formation sometimes happens, especially on freshly prepared plates, and if not corrected would prevent aggregation. 

A unit sometimes confused with a Class I biological safety cabinet is a horizontal laminar flow cabinet or work table. This type of unit serves precisely the opposite function of a class I cabinet. Clean air which has been HEPA filtered is blown across the work surface toward the worker so that the research or product materials are protected against contamination, but the worker is not protected at all. Such a unit is unsuited for microbiological work, except for applications which would cause no harm to the users, such as a work involving noninfectious or non-aUergenic materials. 

The guidelines governing the most favorable location of laminar flow cabinets are essentially the same as for a chemical fume hood. Place them in the far end of a laboratory, in a low traffic area, and where there are no drafts. The environment of the hood should be checked to ensure that air speeds in the neighborhood of the cabinet opening are small compared to the face velocities of the cabinet. 

Immature open-pollinated cones of the Hinoki and Sawara cypress (Fig. lA and Fig. 2A) were collected in June and July from plus mother trees. The collected cones were subsequently disinfected by 1 min immersion in 99.5% ethanol and dried in the laminar flow cabinet before dissection. The excised seeds were disinfected with 1% (w/v available chlorine) sodium hypochlorite solution for 15 min and then rinsed five times with sterile distilled water. After the seed coats had been removed, the megagametophytes containing immature zygotic embryos were used as explants for ECI initiation. 

To reduce risks, parent and sometimes grandparent stocks are retained as backup. On-going maintenance of stock cultures requires skilled staff and specialised equipment (e.g. autoclaves, UV-laminar flow cabinets, controlled-growth rooms). Many hatcheries choose to limit their in-house maintenance of stock cultures, and instead periodically purchase new stock cultures from dedicated culture collections that can guarantee their vitality and quality (Section 4.4.3). 

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