The role of microsurgery in reconstruction of oncologic chest wall defects.

Regional pedicled myocutaneous flaps are usually the best choice for soft-tissue coverage of full-thickness chest wall defects. As defects increase in size, microsurgical techniques are necessary to augment blood flow to pedicled flaps or to provide free flap coverage from distant sites. This study retrospectively reviews all microsurgical procedures performed at one institution for the coverage of full-thickness chest wall defects. Twenty-five cases of full-thickness chest wall reconstruction are reviewed. There were 20 free flaps and five supercharged pedicled flaps. A rectus abdominis myocutaneous flap (free or supercharged) was used in 20 cases, and a filet free flap following forequarter amputation was used in five patients. Large skeletal defects were repaired with a Marlex mesh/methylmethacrylate sandwich prosthesis. There was 100 percent flap survival and one case of minor, partial flap loss. The prosthesis remained effectively covered in all cases. Five patients required ventilatory support for up to 10 days postoperatively. There were three perioperative deaths due to multisystem failure. Microsurgical techniques are extremely useful for reconstruction of complicated, composite chest wall defects. They are indicated when regional pedicled flap options are unavailable or inadequate. These flaps have a 100 percent success rate and uniformly result in stable soft-tissue coverage.     

Identity and change: The example of the falashas,between assimilation in Ethiopia and integration in Israel

Daniel Friedmann is a Research Fellow at the C.N.R.S., Paris. Ulysses Santamaria is a Fellow at the Maison des Sciences de L'Homme, Paris.     

Polyhomeotic: A gene of Drosophila melanogaster required for correct expression of segmental identity

Summary A new locus in Drosophila melanogaster that is required for the correct expression of segmental identity has been discovered. The new locus, termed polyhomeotic (ph), is X-linked and maps cytologically to bands 2D2-3. Homozygous ph flies have homeotic transformations similar to those of known dominant gain of function mutants in the Antennapedia and bithorax complexes (ANT-C, BX-C), and in addition show loss of the humerus. ph interacts with three other similar mutations: Polycomb (Pc), Polycomblike (Pcl), and extra sex comb (esc), and acts as a dominant enhancer of Pc. The expression of ph depends on the ANT-C and BX-C dosage. ph has no embryonic phenotype, but temperature shift studies on ph ² show that the ph ⁺ product is required during embryogenesis and larval development. We propose that ph mutants in some way disrupt the normal expression of the ANT-C and BX-C, and, therefore, that ph ⁺ is needed for maintenance of segmental identity.     

The lack of control of water loss in micropropagated plants is not related to poor cuticle development

To assess if cuticular transpiration could contribute significantly to the high rates of water loss often observed in micropropagated plants after transfer to the nursery, it was tested whether adaxial cuticular water permeance (P) of leaves grown in vitro was higher than that of leaves grown ex vitro. For four species of micropropagated plants with hypostous leaves ( Delphinium elatum hybrid, Doronicum hybrid, Hosta sieboldiana var. elegans, Rodgersia pinnata ), P was determined with two independent techniques which gave similar results. Minimum adaxial overall conductance was measured with the same methods for a Heuchera hybrid which had amphistomatous leaves. Leaves of all species except Heuchera lost 36–65% of their original weight within 25 min after excision. Detached leaves whose abaxial surfaces had been coated lost only 25–38% of their original weight within 5–9 h. Permeances (P) were between 1 × 10⁻⁵ m s⁻¹ and 1 × 10⁻⁴ m s⁻¹, which was within the range of typical values found with leaves grown ex vitro. From these results and a critical assessment of the literature it is concluded that there is no evidence that P of micropropagated plants was high enough to contribute significantly to the desiccation problem at the transfer stage.     

Folding of the polypeptide chain(s), conformational flexibility and reactivity of the metal active site of hemocyanin and tyrosinase

Summary The comparative accessibility of the active sites of hemocyanin and tyrosinase, two proteins containing a binuclear type-3 copper site, has been investigated. The approaches were: (a) the kinetic study of the reaction of hemocyanin with cyanide in the presence of conformation perturbants; (b) the comparison between the kinetic parameters of the cyanide reaction on hemocyanin and tyrosinase; (c) the study of the efficiency and reaction mechanism of hemocyanin interaction with a typical tyrosinase substrate like catechol. The results indicate that the active site of tyrosinase is much more exposed than that of hemocyanin.     

Integrative biology in the discovery of relevant biomarkers monitoring cognitive disorders pathogenesis and progression

Cognitive disorders are highly heterogeneous in terms of symptoms, clinical aetiologies, disease progression and therapeutic responses. Furthermore, their potential biological causes remain largely unknown. Progress at these different levels is currently mired in a vicious circle. The identification of coherent biomarkers, essential for clinical and therapeutic progress, requires an understanding of either the relevant pathogenic processes or, at the very least, of the parameters that need to be monitored. But, syndrome-dominated conceptual thinking has become a barrier to understanding the biological processes linked to diseases characterized by clinical and therapeutic heterogeneity. As a result, current biomarkers of cognitive disorders are much too numerous, too heterogeneous and too variable to serve useful purposes. This leads to an untenable situation that precludes coherent therapeutic developments since it effectively prevents defining what could constitute valid biological, clinical and therapeutic approaches. How to escape from this situation? The problem could be partly resolved by adopting the much wider views allowed by “system-wide” approaches: indeed, by constructing predictive theoretical models of what could constitute pathological cognitive processes. This, naturally, shall require the integration of massive amounts of highly heterogeneous and often conflicting information. The following article aims to provide a necessarily brief overview of the concepts, the breadth of data and the variety of network dynamics that will have to be considered while proposing a functional modelbuilding approach, experimentally validated in vitro and in vivo, that could be fruitfully utilised.     

Fluorescence in situ hybridization and spectral imaging analysis of human oocytes and first polar bodies.

We investigated the frequencies of abnormalities involving either chromosome 1, 16, 18, or 21 in failed-fertilized human oocytes. Although abnormalities involving chromosome 16 showed an age-dependent increase, results for the other chromosomes did not show statistically significant differences among the three age groups, <35 years, 35-39 years, and >39 years. The scoring of four chromosomes is likely to underestimate the true rate of aneuploid cells. Therefore, for a pilot study investigating a more-comprehensive analysis of oocytes and their corresponding first polar bodies, we developed a novel eight-probe chromosome enumeration scheme using fluorescence in situ hybridization and spectral imaging analysis.