Reduced cellular toxicity of a new silver-containing antimicrobial dressing and clinical performance in non-healing wounds.

Bacterial colonisation of wounds may delay wound healing. Modern silver-containing dressings are antimicrobial, yet cellular toxicity is a serious side-effect. We provide data for a newly formulated silver-containing ointment dressing, Atrauman Ag, for antimicrobial activity and cytotoxicity. Atrauman Ag effectively killed a panel of commensal skin as well as pathogenic bacterial strains while cytotoxicity for HaCaT keratinocytes was only around 10%. With these favourable in vitro tests, Atrauman Ag was analysed in 86 patients with traumatic and non-healing wounds of different aetiologies. The wound state was evaluated for 3 subsequent dressing changes. The slough score was reduced from 59.2 to 35.8%, granulation tissue increased from 27 to 40% and epithelialisation went up from 12.1 to 24%. We conclude that Atrauman Ag has a superior profile of antimicrobial activity over cellular toxicity and the low silver ion release rate may prevent interference with wound-healing mechanisms.

Behavioral analysis of polarization vision in tethered flying locusts.

For spatial navigation many insects rely on compass information derived from the polarization pattern of the sky. We demonstrate that tethered flying desert locusts (Schistocerca gregaria) show e-vector-dependent yaw-torque responses to polarized light presented from above. A slowly rotating polarizer (5.3 degrees s(-1)) induced periodic changes in yaw torque corresponding to the 180 degrees periodicity of the stimulus. Control experiments with a rotating diffuser, a weak intensity pattern, and a stationary polarizer showed that the response is not induced by intensity gradients in the stimulus. Polarotaxis was abolished after painting the dorsal rim areas of the compound eyes black, but remained unchanged after painting the eyes except the dorsal rim areas. During rotation of the polarizer, two e-vectors (preferred and avoided e-vector) induced no turning responses: they were broadly distributed from 0 to 180 degrees but, for a given animal, were perpendicular to each other. The data demonstrate polarization vision in the desert locust, as shown previously for bees, flies, crickets, and ants. Polarized light is perceived through the dorsal rim area of the compound eye, suggesting that polarization vision plays a role in compass navigation of the locust.

Tumor progression of skin carcinoma cells in vivo promoted by clonal selection, mutagenesis, and autocrine growth regulation by granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor.

Tumor microenvironment is crucial for cancer growth and progression as evidenced by reports on the significance of tumor angiogenesis and stromal cells. Using the HaCaT/HaCaT-ras human skin carcinogenesis model, we studied tumor progression from benign tumors to highly malignant squamous cell carcinomas. Progression of tumorigenic HaCaT-ras clones to more aggressive and eventually metastatic phenotypes was reproducibly achieved by their in vivo growth as subcutaneous tumors in nude mice. Their enhanced malignant phenotype was stably maintained in recultured tumor cells that represented, identified by chromosomal analysis, a distinct subpopulation of the parental line. Additional mutagenic effects were apparent in genetic alterations involving chromosomes 11 and 2, and in amplification and overexpression of the H-ras oncogene. Importantly, in vitro clonal selection of benign and malignant cell lines never resulted in late-stage malignant clones, indicating the importance of the in vivo environment in promoting an enhanced malignant phenotype. Independently of their H-ras status, all in vivo-progressed tumor cell lines (five of five) exhibited a constitutive and stable expression of the hematopoietic growth factors granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, which may function as autocrine/paracrine mediators of tumor progression in vivo. Thus, malignant progression favored by the in vivo microenvironment requires both clonal selection of subpopulations adapted to in vivo growth and mutational events leading to stable functional alterations.

An example of regional variation in the tempos of tooth mineralization and hand-wrist ossification.

Two groups of adolescent orthodontic patients, one from the Midwest and one from the Midsouth, were compared to test the clinical impression that the permanent teeth of southern children form and erupt at significantly later ages. Indeed, a marked difference is documented, with the Midsouth series achieving mineralization stages at least 1 1/2 years later on average. This suggests that regional differences are appreciably greater than previously suspected. Clinical consequences revolve on the use of conventional (generally Northeast-based) norms for tooth formation and eruption and predictive models of facial growth. In contrast, the analysis of rates of hand-wrist development (bone age) of these same subjects disclosed no difference; this further confirms the essential independence of development of the dental and osseous tissue systems.