Beobachtungen zum Mosaizismus beim Cri-du-chat-Syndrom

Summary Two cases of the cri-du-chat-syndrome are described, one with mosaicism in regard to the deletion, the other with probable differences of the size of the deletion. In both cases there have been found a few cells, where the distal part of the short arm of a B-chromosome has been satellited.     

Bilateral detection thresholds in dextrals and sinistrals reflect the more sensitive side of the nose, which is not lateralized [published erratum appears in Chem Senses 1998 Dec;23(6):761]

Several fundamental questions remain enigmatic concerning human olfactory sensitivity, including (i) whether detection threshold differences exist between the two sides of the nose (and, if so, whether such differences are influenced by handedness) and (ii) whether bilateral (i.e. binasal) stimulation leads to lower thresholds than unilateral stimulation (and, if so, whether the degree of facilitation is inversely related to general olfactory ability). In this study, and well-validated single staircase procedure was used to establish bilateral and unilateral detection thresholds for the cranial nerve I stimulant phenyl ethyl alcohol in 130 right- and 33 left-handed subjects. No differences in sensitivity between the left and right sides of the nose were observed in either group. Bilateral thresholds were lower, on average, than unilateral thresholds when the latter were categorized in terms of left and right nares. However, the bilateral thresholds did not differ significantly from those of the side of the nose with the lower threshold. Overall smell ability, as measured by the University of Pennsylvania Smell Identification Test, did not interact with any of the test measures. These data imply that (i) the left and right sides of the nose do not systematically differ in detection threshold sensitivity for either dextrals or sinistrals and (ii) if central integration of left:right olfactory threshold sensitivity occurs, its effects do not exceed the function of the better side of the nose.      

Morphogenic Regulation of Pathotoxin Synthesis in Cochliobolus carbonum

The fungus Cochliobolus carbonum causes leaf spot disease of maize. Highly virulent isolates of the pathogen produce a host-selective, peptide toxin that is active against susceptible genotypes of maize. Prior to infection, spores must germinate and differentiate appressoria, structures specialized for leaf penetration. Analysis of spore germination fluids by plasma desorption mass spectrometry, which allowed detection of as little as 0.5 ng toxin, revealed that spores induced to form appressoria in vitro synthesized and released the toxin at a time coincident with maturation of appressoria. Spores incubated under conditions that did not induce appressorium formation failed to produce toxin. These observations indicate that synthesis of the host-selective toxin, which is essential for successful pathogenesis of maize by C. carbonum, is regulated by infection-related morphogenesis.     

On the Analysis and Synthesis of a Four-Field-Table

The real four-field-table measure k is calculable as follows: K₁ for V(a, b, c, d) with k₁ = (arc K₁)/100, K₁₁ for V(a, b, 0, 0) with k₁₁ = (arc K₁₁)/100, K₁₂ for V(c, d, 0, 0) with k₁₂ = (arc K₁₂)/100 and K₁₂₁ for V(0, 0, c, d) with k₁₂₁ = – k₁₂. The equation k₁ = k₁₁ – k₁₂ holds good. It is possible to calculate the probability of error of a four-field-table with small frequencies, indirectly from component values. Two examples are given.     

Zahlenverhältnisse von Häufigkeiten

In evaluating data, one acknowledges as a scientist the superiority of the K-procedure on account of the versatility of its application, e.g. in answering the question not only as to its causal context, in proving two features to be contemporaneous and equally strong effects of a material third factor, or in accordance with a “criterion of parallel problems”, but also in demonstrating the mutual matching of two frequency-ratios and the matching of one frequency-ratio with a given proportion, e.g. 3: 1, and the matching of a continuing proportion collected from observed frequencies with a given continuing proportion, e.g. 9:3:3: 1. This is demonstrated in the examples in the literature, which hitherto have been treated only according to the classical procedure.     

Measurement of the Relation of Two Characteristics

The four-field table measure K (appearing as K₁, K₂), which is only a coefficient-measure, can, by means of a useful transformation, be transformed into a real measure k by means of a graduated scale. The measure k can be compared with other k-values and, futhermore, reveals directly, by how many per cent the one characteristic can be looked upon as being determined by the other characteristic of the two characteristics under review.     

Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.