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Triphenyl-methan dyes, traditionally used in dermatology should be reevaluated with caution. Their use should be limited due to the uncertain pharmacological-toxicological risk-benefit ratio and the lack of pharmacological quality of the raw substances. Sometimes antimicrobial activity is insufficient and the cytotoxic effects, along with the inhibition of wound healing, make these dyes less suitable for topical treatment in dermatology. Chinolinolsulfat (Chinosol) and Clioquinol should be used in low concentrations and only on small areas. Due to their negative benefit-risk profile ethracidinlactate-monohydrate (Rivanol) and phenylmercuri-borate (Mercuchrom) should not be used as topical antimicrobial substances. The present publication is intended to give practical recommendations on compounded medications for topical antimicrobial use. Even though some of the cited compounds must be considered critically, we recommend the topical use of chlorhexidine salts, polihexanide, triclosan, polyvidone iodide and silver compounds. Useful standardised compounded formulations containing these four groups are listed in the NRF (Neues Rezeptur Formularium: New German Pharmacopoeia for compounded medication).

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Cecropin B is a small antibacterial peptide from the giant silkmoth Hyalophora cecropia. To reveal the potential of this peptide for engineering bacterial disease resistance into crops, several cecropin B gene constructs were made either for expression in the cytosol or for secretion. All constructs were cloned in a plant expression vector and introduced in tobacco via Agrobacterium tumefaciens. A cDNA-derived cecropin B gene construct lacking the amino-terminal signal peptide was poorly expressed in transgenic plants at the mRNA level, whereas plants harbouring a full-length cDNA-derived construct containing the insect signal peptide, showed increased cecropin B-mRNA levels. Highest expression was found in plants harbouring a construct with a plant-gene-derived signal peptide. In none of the transgenic plants could the cecropin B peptide be detected. This is most likely caused by breakdown of the peptide by plant endogenous proteases, since a chemically synthesized cecropin B peptide was degraded within seconds in various plant cell extracts. This degradation could be prevented by the addition of specific protease inhibitors and by boiling the extract prior to adding the peptide. In addition, anionic detergents, in contrast to cationic, zwitter-ionic or non-ionic detergents, could prevent this degradation. Nevertheless, transgenic tobacco plants were evaluated for resistance to Pseudomonas solanacearum, the causal agent of bacterial wilt of many crops, and P. syringae pv. tabaci, the causal agent of bacterial wildfire, which are highly susceptible to cecropin B in vitro. No resistance was found. These experiments indicate that introduction and expression of cecropin B genes in tobacco does not result in detectable cecropin B protein levels and resistance to bacterial infections, most likely due to degradation of the protein by endogenous proteases.

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The modulation transfer function (MTF) of a screen-film system can be measured by two methods, i.e., a slit method with Fourier transform on the line spread function and a square-wave response function (SWRF) method. However, it is still uncertain whether MTFs obtained by the two methods are identical. In this study, MTFs of relatively sharp and unsharp screen-film systems were measured by using the two methods. The slit method provided slightly greater MTF for the relatively sharp system than the SWRF method. However, MTFs of the unsharp system obtained with the two methods were comparable. Generally, the slit method tends to provide reliable results for unsharp systems, whereas the SWRF method is favorable for sharp systems. Accuracy and consistency of these measurements were examined by comparison of experimental and theoretical edge responses derived from the measured MTFs. However, the difference in edge responses obtained by the two methods was relatively small compared with the variation of the measured edge responses, and thus results were considered inconclusive as to whether either of the methods can provide more accurate MTFs. International interlaboratory comparison indicated that the variation in the measured MTFs at six different institutions was relatively large for both methods. However, the MTFs of two screen-film systems measured by the slit method appear to agree with those by the SWRF method within the variation expected from the interlaboratory comparison.

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The information obtainable from a radiograph depends on the viewing conditions under which the radiograph is viewed. All the viewing conditions can be defined in terms of scattered light. The amount of information taken from a radiograph with S = 1000 (S = speed class) and perfect conditions is the same as that from a radiography with S = 100 viewed under poor conditions. The optimum illuminance for the radiograph viewing room is 50 lx diffuse. The influence of scattered light is small enough to cause only a small loss of information. With the illuminance of 50 lx diffuse in the viewing room and Lo = 2000 cd/m2, the density range should be delta D = 2.85. The scattered light reduces it to delta D = 2.60 when the radiograph is viewed under the above-mentioned circumstances.

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It is shown that the number of contrasts which can be differentiated on a radiograph depends on the detail size, the noise, and the viewing conditions. The minimum signal-to-noise ratio (SNR) for a perception approach is equivalently described by the SGA value. This testing method was first developed by De Belder and Bollen to examine the visibility of low contrast details. The correlation between the SGA and the speed class S of the system can be explained by this method.

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The present article describes the circumstances concerning the use of testing aids such as sensitometers with one-sided exposure. It is shown which phenomena must be considered if radiographic films coated on both sides are exposed with a) standard pocket sensitometers (one-sided exposure), b) lab sensitometers (double-sided exposure to ANSI Ph 2.9 [1964]), c) x-radiation in the cassette, intensifying screen and film system (to DIN 6867 T 1). The effect of the emission spectrum on the resulting contrast factor is described. The importance of different emulsion technologies (e.g. orthochromatic anticross-over films) for the contrast factor with one-sided exposure is described. The cross-over factor (c.o.), the apparent variation in sensitivity of the front and back emulsion with one-sided exposure, is the cause of the reduction in the contrast factor (G average) as against double-sided exposure: delta G(%) = c.o.2 x 10(3)/8.4

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