Autoclavable ultrahigh-efficiency filter for use with flexible film germfree animal isolators

An autoclavable ultrahigh-efficiency filter unit, which accommodated 99.98% efficient respirator filter cartridges, was built for use with flexible film germfree animal isolators.     

The use of flexible film isolators for housing experimental animals

The change-over from conventional husbandry to the housing of minimal-disease experimental animals kept in flexible-film isolators resulted in improved survival and thus more definitive experimental results. The disadvantages and advantages of the change are discussed.     

An autoclavable electronic interface for germfree isolators

An electronic interface was designed and fabricated for use with germfree isolators. It allows a variety of sensors or electrical instruments inside an isolator to be readily connected to monitoring or activating devices on the outside of an isolator. It was built into a 25 cm diameter cylinder whose open ends were loosely covered by an inner and outer connector panel. These two panels were wired together through an airtight dividing wall placed transversely across the middle of the cylinder. The interface was mounted in an entry port of a stainless steel isolator and steam sterilized with the isolator. It has proven to be a useful, contamination-free, durable device.     

An alternative method for the decontamination of rats carrying Mycoplasma pulmonis without the use of germfree isolators

Two strains of Lewis rat were successfully freed from Mycoplasma pulmonis infection by using a combination of oral treatment with oxytetracycline hydrochloride and obtaining young by hysterectomy. Laminar flow cabinets were used to perform hysterectomies on donor animals and for rearing hysterectomy-derived animals. After thorough microbiological examination the rats were brought to the breeding colony of the Laboratory Animal Centre. Periodic laboratory tests using both cultural and enzyme-linked immunosorbent assay methods showed that the animals have remained free from M. pulmonis for the last 3 years.     

Seaweeds for animal production use

Early scientific studies conducted at the turn of the twentieth century failed to support the inclusion of seaweeds into animal rations at high inclusion rates. At that time, based on proximate analysis and energy availability studies, dried seaweeds or kelp meal largely fell out of favor as a recommended animal feed source. Nevertheless, kelp meal was still regarded by some as having properties which improved animal health and productivity which were not conveniently explained by conventional feed analysis. In the 1970s, research leads to the discovery that chelated micromineral sources were more efficient for the delivery of microelements than conventional inorganic sources. This prompted renewed interest in seaweeds as rich sources of over 60+ microelements. However, it was only in the early 2000s, when detailed analysis of the complex structure of the polysaccharides associated with seaweeds was tied to their prebiotic actions, that a clear explanation for the basis of productivity and health enhancement was attained. Further analysis indicated that other constituents in various brown seaweeds such as phlorotannins and antioxidants also contributed to the observed bioactivities. Of all of the brown seaweeds cited in studies, the one most scientifically documented is Ascophyllum nodosum, and of all of these sources, Tasco®, a sundried, high-quality macroalgal product, produced by Acadian Seaplants has been the most studied. The latest studies of Tasco® suggest prebiotic potencies at least five times that of the reference prebiotic inulin with additional performance-enhancing benefits in animal rations that rival antibiotic inclusions.     

An evaluation of a water purification system for use in animal facilities

A commercially available water purification system was evaluated for its ability to minimize chemical and microbial contaminants. The reduction or removal of these impurities from the drinking water of experimental animals would reduce experimental variability. 3 strains of bacteria were collected from the processed water. An increase in the total number of bacteria was observed the longer the filters remained in use. Determinations of heavy metals in water samples before and after processing were made for lead, zinc, copper, nickel, manganese, iron, arsenic and mercury. Calcium and magnesium levels were also determined. The concentrations of these inorganic chemicals were reduced by the purification process except at 2 time points in which desorption of the chemical could have occurred. Bacterial colonization and desorption of these chemicals were controlled by installing new filter cartridges. Volatile halocarbon concentrations were determined for water samples before and after purification. All volatile halocarbons analyzed were less than 10 ppb before and after purification at all time points. Other organic chemicals were greatly reduced by the purification process. In a study of contaminants associated with installation of the unit, it was found that flushing the unit for 8 days reduced lead and methyl ethyl ketone concentrations to insignificant levels. The purification system was found to be effective in providing high quality drinking water as verified by a microbial and chemical testing program.     

Method for bulk culture of animal cells on plastic film

A method is described for the culture of anchorage-dependent cells, on rolls of transparent, autoclavable plastic film. The film is wound into the form of a disposable spiral, which is inserted into a culture vessel. A 2 1 plastic vessel contains a spiral of surface 8 000 cm², i.e. ten times the internal surface of a comparable 2.2 1 glass, roller-bottle. Growth tests were performed on primary (mouse whole embryo), and established (BHK) cells. Specific cell yields, per ml of medium, were similar for both methods (5–7 × 10⁵ cells/ml), but the total cell yield from the plastic spiral (10⁹ cells/vessel) was eight times greater than that from the glass roller bottle (1.2–1.5 × 10⁸ cells). The present apparatus seems capable of mass-production as a cheap, disposable vessel for larger-scale tissue culture.     

Training for reduction in laboratory animal use

Reduction, refinement and replacement of laboratory animals wherever possible, are the guiding principles of the Federation of European Laboratory Animal Science Associations (FELASA) education guidelines. Of these, reduction is probably the least understood. Reduction and refinement are dependent upon each other. In the reduction "axis", there is a window of appropriate numbers of animals; too few and the experiment will lack power--too many and animals will be wasted. Reduction must be understood as the appropriate number of animals required for each experiment. The refinement "axis" is more straightforward. Better welfare is always desirable. Any factor can interfere with a study in two ways. If it changes the mean, this may not be serious, because it should do so in all groups. If it causes a change in variation, then this is far more troublesome, because this is bound to alter the appropriate number of animals for an experiment. Scientists are definitely concerned about the variation of the characters that they are working with. It is obvious that changes in variation may be study-specific, which makes the formulation of overall guidelines difficult. Indeed, instead of trying to assess the impact of housing and procedures on every possible character, it could be more productive to look at the effects of welfare indicators on variation, with the understanding that low variation here is likely to be reflected by low variation in most other characters, while aiming to achieve the most uniform welfare of the animals in the study.     

An accurate method for estimating 5-phosphoribosyl 1-pyrophosphate in animal tissues with the use of acid extraction.

In determination of the tissue content of 5-phosphoribosyl 1-pyrophosphate (PRPP), heat treatment has been generally used for the extraction. However, the procedure appeared to need well-controlled conditions which should be determined for each different tissue by preliminary examinations. Thus, extraction with perchloric acid was examined and found to give satisfactory results if combined with rapid processing of the tissues. The decomposition of the compound, though less than 20% by the procedure used, was corrected based on the recovery of ³H-labeled PRPP which was added at the step of homogenization. The acid extraction eliminated interfering enzyme activities in the extract and assured, together with the use of the internal standard, a high degree of reproducibility. It was also shown that the duration of anoxia that inevitably happens when animal tissues are excised must be minimized to the order of a few seconds.     

An integrated database for managing animal study proposals and animal inventory for the small animal facility

The authors describe how they created a user-friendly, multifunctional database for use by a variety of vivarium staff.