Pietra Serena Mining in Fiesole. Part II: Geological Situation

The results are presented for the investigations into the geological estimate of Macigno formation representing an Oligocene-Miocene turbiditic sequence of the Northern Apennines, from the coarse-graded beds of which the Pietra Serena quarry stone was mined. It is shown that the sedimentological features, the physico-mechanical properties, and the mineralogical composition of rocks govern the distinctions in the operating performances.     

Constitutive promoter modules for PCR-based gene modification in Saccharomyces cerevisiae

Initial steps in investigating gene function often include deleting and overexpressing the gene of interest and identifying the subcellular location of the gene product. To facilitate these procedures, a number of new PCR modules, which contain selectable markers and in some cases other genetic elements (e.g promoter elements, epitope tags, and reporter genes) have been developed. These modules are used as PCR substrates to create products that can be targeted to specified locations in the yeast genome, thus modifying that genomic locus. We describe here a series of plasmids that contain a truncated version of the strong ADH1 promoter with and without amino-terminal 3HA and GST tags. Because these plasmids contain the same vector sequences as the GAL1 promoter plasmids, a constitutive and an inducible promoter can now be integrated with a minimal number of primers.     

The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase III) surfactant-based formulations

The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.     

Arthroscopy in hand surgery

As arthroscopy of the wrist moves into the second decade, the trend for more indications for both diagnostic and therapeutic procedures will continue. It is only a matter of time before arthroscopic fusions, soft-tissue repairs, and "ectomy" procedures of all kinds become more commonplace. Whereas the advantages of the early therapeutic techniques in preserving soft-tissue structures and shortening recovery are now obvious, we will have to wait and see if the same holds true for more complicated bony and soft-tissue procedures in the next decade.     

Mechanisms of expression of pyruvate dehydrogenase deficiency caused by an E1alpha subunit mutation

OBJECTIVE: To characterize the biochemical mechanisms of expression of the pyruvate dehydrogenase (PDH) E1alpha subunit exon 10 R302C missense mutation. BACKGROUND: Mutations in the X-linked E1alpha subunit gene are responsible for most cases of PDH deficiency, an important cause of neurodevelopmental defects and neurodegeneration with primary lactic acidemia. Although the disease shows extreme allelic heterogeneity, the R302C mutation has been defined in several unrelated cases. METHODS: Cell lines expressing selectively either the mutant or wild-type E1alpha alleles against identical genetic backgrounds were generated from the fibroblasts of a female heterozygous for the R302C mutation. Enzyme activity, mRNA, polypeptide expression, and turnover were studied in each. RESULTS: The residual PDH activity was below measurable levels in the cell line (B5) expressing only the mutant allele and normal in the wild-type polypeptide expressing (A10) cell line, confirming that the R302C mutation alone is sufficient to cause a severe PDH deficiency. The mutant polypeptide was less stable than the wild-type polypeptide, but the steady-state level of the mutant E1alpha protein was reduced only two- to threefold. CONCLUSIONS: The primary mechanism of expression of the R302C mutation must be limitation of catalytic efficiency. We speculate that catalysis may be inhibited in the mutant polypeptide because conformational changes are induced near serine 300, a residue that is particularly important as a regulatory phosphorylation site in the wild-type polypeptide.