Challenge test

Verification of the microbial retention efficiency of the membrane filters may be undertaken using either Hquid or aerosol challenge tests. A Hquid challenge test is more stringent. Furthermore, this test can provide retention information for process conditions such as extreme moisture after sterilization or air entrained with water drops. A Hquid challenge is performed using a protocol similar to that described for Hquid filtration. 

Membrane thickness is a factor in microbial retention, Tortiioiis-pore membranes rated at 0,22 jlrn tvpicallv have surface openings as large as 1 jlrn (Fig, 22-71), Narrovv er restrictions are found beneath the surface. In challenge tests, P. diminnta organisms are found vv ell beneath the surface of an 0,2 jlrn membrane, but not in the permeate. 

Rueff F, Przybilla B, Muller U, Mosbech H Position paper The sting challenge test in Hymenoptera venom allergy. Allergy 1996 51 216-225. 51... 

Wasserfallen JB. Frei PC Long-term evaluation of 39 usefulness of skin and incremental challenge tests in patients with history of adverse reaction to local anesthetics. Allergy 1995 50 162-165. 

Leak R.E. Leech R. (1988) Challenge tests and their predictive stability. In Microbial Quality Assurance in Pharmaceuticals, Cosmetics and Toiletries (eds S.F. Bloomfield, R. Baird, R.E. Leak R. Leach), pp. 129-146. Chichester Ellis Horwood. 

Orth has applied the concepts of the D-value as used in sterilization technology (Chapter 20) to the interpretation of challenge testing. E q)iessing of the rate of microbial inactivation in a preserved system in terms of a D-value enables estimation of the nominal time to aehieve a prescribed proportionate level of kill. Problems arise when trying to prediet the behaviour of very low levels of survivors, and the method has its detractors as well as its advocates. 

Coupland, N, Glue, P and Nutt, DJ (1992) Challenge tests assessment of the noradrenergic and GABA systems in depression and anxiety disorders. Molec. Aspects Med. 13 221-247. 

Calibration and maintenance programs [45], challenge tests [2], accelerated shelf life tests [53], auditing [2], sensory tests [46], microbial tests [47]... 

Challenge testing to estimate stabilities of chemicals in specific foods... 

The long lasting efficacy of a 2.512.5% MIT/BIT formulated product is demonstrated by multi-challenge testing carried out in two water-based paints in which its activity was compared with that of a 1.5% CIT/MIT formulation (Figure 18.). 

A further complication is that different airlines demand different test protocol. Some use raw sewage in tests, some do not. Others use a combination of tests to simulate the different conditions experienced in toilet tanks. British Airways for example use a simple challenge test that is useful for screening. 

Duplicate counts are made using serial dilutions up to 10-6 and drop plates. Solutions are then spotted onto blood agar plates and incubated at 37 °C for 18 hours after which the number of colony forming units is determined. To pass the BA Challenge Test there must be no growth from the aliquots taken at 15 minutes or more from the 1 400 and 1 1600 dilutions. 

The table 1 summarises the challenge test data using Myavert C 5 part enzyme based preservation in a face mask 1 including speed of kill test to justify positive marketing claims for the anti-microbial system used in the product. Table 2 uses conventional chemical anti-microbials for a foot product at much higher levels than would be allowed for face application yet the speed of kill of the enzyme system is superior yet much more mild. 

An Array of Challenges — Test Your SAS0 Skills by Robert Virgile... 

Since the integral method described above is based on the premise that some rate function exists that will lead to a value of i/ Cj) that is linear in time, deviations from linearity (or curvature) indicate that further evaluation or interpretation of the rate data is necessary. Many mathematical functions are roughly linear over sufficiently small ranges of variables. In order to provide a challenging test of the linearity of the data, one should perform at least one experimental run in which data are... 

Screening for gestational diabetes mellitus utilizes the oral glucose challenge test. Groups at high risk are African Americans, Native Americans, Asian Americans, Latino Americans, and Pacific Islanders. 

Spirometry demonstrates obstruction (forced expiratory volume in 1 second [FEVJ/forced vital capacity less than 80%) with reversibility after inhaled P2-agonist administration (at least a 12% improvement in FEVj). Failure of pulmonary function to improve acutely does not necessarily rule out asthma. If baseline spirometry is normal, challenge testing with exercise, histamine, or methacholine can be used to elicit BHR. 

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