Factorial studies

The second experiment (Feron et al. 1995a, Groten et al. 1997) was a 4-week oral/inhalatory study in male Wistar rats in which the toxicity of combinations of nine compounds was examined (Table 10.6) in a complex design. The study comprised a main study and a satellite study. In the main study, the rats were simultaneously exposed to mixtures of aU nine chemicals. The satellite study was designed as a fractionated two-level factorial study in which the rats were simultaneously exposed to combinations of maximally five compounds at their LOAEL these 16 combinations of 9 factors (9 chemicals) jointly comprise a 1/32 fraction of a complete study. 

Generally, high space velocities of ammonia and low temperature ramp rates are required for maximisation of surface area. The former has the effect of reduction in the partial pressure of water vapour generated on reaction, whilst the latter minimises sintering by solid-solid reaction. In a factorial study, Choi... 

Philip P, Vervialle F, Le Breton P, Taillard J, Home JA. Fatigue, alcohol, and serious road crashes in France factorial study of national data. Br Med J 2001 322 829-830. 

Gaertner JG, Dhurjati P (1993), Fractional factorial study of hybridoma behavior. 2. Kinetics of nutrient uptake and waste production, Biotechnol. Prog. 9 309-316. 

Another study revealed effects, ranging from mild to severe, of benzene exposure in factory workers in China (Yin et al. 1987c). The primary activities in these factories were the manufacture of paints, shoes, rubber, leather, and/or adhesives (Yin et al. 1987c). Of the 528,729 workers, 95% were exposed to mixtures of benzene, toluene, and xylene, while 5% (26,319 workers) were exposed to benzene alone at 0.02-264 ppm in air in 95% of the work stations. Over half of the work stations had levels of benzene in the air of less than 13 ppm about 1% had levels of 13-264 ppm. Benzene toxicity, as indicated by leukopenia (leukocyte <4,000/mm3), aplastic anemia, and leukemia, was seen in 0.94% of the workers exposed to benzene and 0.44% of the workers exposed to the mixtures. Similar toxicity was found in employees of 28 of the 141 shoe factories studied (124 cases in 2,740 employees) (Yin et al. 1987c). A positive correlation was observed for prevalence of adverse benzene effects and benzene concentration in data from these 28 shoe factories. The authors determined that the affected people were exposed to benzene concentrations >29 ppm. In one workshop, there were 4 cases of aplastic anemia in 211 workers. These workers were exposed to benzene at a mean concentration of 324 ppm during an 8-month period of employment. The prevalence of aplastic anemia in the shoe-making industry was about 5.8 times that in the general population. The main limitation of this study is the lack of information on the duration of exposure. 

Oliyai et al. [23] studied an Asn-hexapeptide (Val-Tyr-Pro-Asn-Gly-Ala) in lyophilized formulation as a function of pH of the bulk solution, temperature, and residual moisture content in a factorial study. A statistically significant two-factor interaction indicated that the pH of formulation solution determined the extent to which this peptide stability depends on moisture level and temperature. 

Kaewvichit, S. Tucker, I.G. The release of macromolecules from fatty acid matrices complete factorial study of factors affecting release. J. Pharm. Pharmacol 1994, 46, 708-713. 

In addition to the development of the procedure outlined above, a factorial study was conducted in the laboratory to study several variables in an attempt to improve growth (Johnson et al. 1997 Togkalidou et al. 2001). The experiments consisted of a six-variable fractional factorial of 10 runs followed by experimental verihcation. 

Results from the factorial study indicate that the primary input variables affecting filtration resistance were seed type and mixing intensity. When slurry seed was used, insufficient slurry seed led to... 

Based upon the results of the factorial study, the manufacturing-scale centrifuge filtration time (6000 X scale) was reduced 73% from the simultaneous addition process developed in Option 2 above. 

Marshall Stability. A factorial study was made to determine the Marshall stability for mix compositions with asphalt contents of 2-10% and sulfur contents of 0-20 wt % of mix. The mix stability of the two-... 

We may take the results of the 2 factorial study of an effervescent table formulation reported earlier, and select the data corresponding to the 12 experiments of table 3.31. Estimates of the coefficients obtained either by contrasts or by the usual method of multi-linear regression are very close to those estimated from the... 

It has also been the case that clinical trials have not been particularly representative as regards the patients studied. For example, it has been claimed that women have often been under-represented for various reasons, not least because fear of damaging the unborn has led sponsors to exclude many women of child-bearing age from their trials. A particular trial in which this certainly was the case was the Physician s Health Study (Hennekens and Eberlein, 1985) in which 22 071 male US physicians were the subjects in a factorial study designed to look at the possible prophylactic effects of aspirin... 

Chow OKW, Fung KP, Slow-release terbutaline and theophylline for the loi -term therapy of children with asthma A latin square and factorial study of drug effects and interacticxis. Pediatrics 9Z9) 84,119-25,... 

Andrade, V.S., Neto, B.d.B., Fukushima, K., and Campos-Takaki, G.M. 2003. Effect of medium components and time of cultivation on chitin production by Mucor circinelloides (Mucor javanicus IFO 4570)—JS factorial study. Rev Iberoam Micol. 20 149-153. 

This state of affairs is perhaps not surprising when one considers that in one Soviet /t-paraffin-based SCP factory studies showed that some of the workforce were exposed to dense aerosols of up to 436 000 cells per m in their work place.This would appear to exceed the limits set by the USSR Ministry of Health by a factor of 400 (see section 5.3.2). The escape of such large quantities of micro-organisms into the work environment at this (unnamed) plant was ascribed to lack of containment in equipment, the flow of microbiological material through open chutes and the intake of contaminated air through the ventilation systems. 

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