Assessment of Optimal Selected Prognostic Factors

The identification and assessment of prognostic factors is one of the major tasks in clinical research. The assessment of one single prognostic factor can be done by recently established methods for using optimal cutpoints. Here, we suggest a method to consider an optimal selected prognostic factor from a set of prognostic factors of interest. This can be viewed as a variable selection method and is the underlying decision problem at each node of various tree building algorithms. We propose to use maximally selected statistics where the selection is defined over the set of prognostic factors and over all cutpoints in each prognostic factor. We demonstrate that it is feasible to compute the approximate null distribution. We illustrate the new variable selection test with data of the German Breast Cancer Study Group and of a small study on patients with diffuse large B‐cell lymphoma. Using the null distribution for a p‐value adjusted regression trees algorithm, we adjust for the number of variables analysed at each node as well. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evaluation of environmental conditions for production of bacteriocin-like substance by <Emphasis Type="Italic">Bacillus</Emphasis> sp. strain P34

The influence of temperature, pH and media on bacteriocin production by Bacillus sp. P34 was investigated. The effect of temperature and initial pH was evaluated by factorial design and response surface methodology (RSM). Statistical analysis of results showed that, in the range studied, the two variables have a significant effect on bacteriocin production. Response-surface data showed maximum antimicrobial activity production at initial pH values between 6.0 and 8.0 and temperatures between 25 and 37 °C. No relationship between bacterial growth and bacteriocin production was observed. RSM proved to be a powerful tool in optimizing the production of antimicrobial activity by Bacillus sp. P34. When different media were tested, maximum bacteriocin production was observed in soybean protein-based medium, but antimicrobial activity was not achieved by cultivation on fish meal, feather meal, whey and grape waste.     

Extended statistical approaches to modelling spatial pattern in biodiversity in northeast New South Wales. II. Community-level modelling

Regional conservation planning can often make more effective use of sparse biological data by linking these data to remotely mapped environmental variables through statistical modelling. While modelling distributions of individual species is the best known and most widely used approach to such modelling, there are many situations in which more information can be extracted from available data by supplementing, or replacing, species-level modelling with modelling of communities or assemblages. This paper provides an overview of approaches to community-level modelling employed in a series of major land-use planning processes in the northeast New South Wales region of Australia, and evaluates how well communities and assemblages derived using these techniques function as surrogates in regional conservation planning. We also outline three new directions that may enhance the effectiveness of community-level modelling by: (1) more closely integrating modelling with traditional ecological mapping (e.g. vegetation mapping); (2) more tightly linking numerical classification and spatial modelling through application of canonical classification techniques; and (3) enhancing the applicability of modelling to data-poor regions through employment of a new technique for modelling spatial pattern in compositional dissimilarity.     

cDNA and amino acid sequences of rainbow trout (Oncorhynchus mykiss) lysozymes and their implications for the evolution of lysozyme and lactalbumin

Summary The complete 129-amino-acid sequences of two rainbow trout lysozymes (I and II) isolated from kidney were established using protein chemistry microtechniques. The two sequences differ only at position 86, I having aspartic acid and II having alanine. A cDNA clone coding for rainbow trout lysozyme was isolated from a cDNA library made from liver mRNA. Sequencing of the cloned cDNA insert, which was 1 kb in length, revealed a 432-bp open reading frame encoding an amino-terminal peptide of 15 amino acids and a mature enzyme of 129 amino acids identical in sequence to II. Forms I and II from kidney and liver were also analyzed using enzymatic amplification via PCR and direct sequencing; both organs contain mRNA encoding the two lysozymes. Evolutionary trees relating DNA sequences coding for lysozymesc and α-lactalbumins provide evidence that the gene duplication giving rise to conventional vertebrate lysozymesc and to lactalbumin preceded the divergence of fishes and tetrapods about 400 Myr ago. Evolutionary analysis also suggests that amino acid replacements may have accumulated more slowly on the lineage leading to fish lysozyme than on those leading to mammal and bird lysozymes.     

Statistical assessment of population variability: a methodological approach

We have implemented a multivariate statistical methodology to assess the degree and pattern of cranial variability in skeletal samples. Specifically, the method is designed to test whether variability in a skeletal sample exceeds "normal within-group variability" defined in the present instance as variability present among crania from a cemetery associated with a village. It involves comparing a covariance matrix derived from a sample of unknown composition to one representing "normal within-group variability." The method has been applied to two Plains Indian craniometric samples. The Leavenworth site (39CO9) represents the remnants of previously autonomous Arikara Indian villages devastated by epidemic diseases in the late 1700s. The Bad River 2 Phase is an archaeological designation grouping together closely related sites in the Bad-Cheyenne region of South Dakota dating from 1740-1795 AD. We were able to show substantial heterogeneity among crania from Leavenworth. District burial areas at Leavenworth account for some of the heterogeneity, supporting the notion that they represent an attempt to maintain former social distinctions. We were unable to differentiate among sites within the Bad River 2 Phase, suggesting that it is a valid biological unit.