Nonsurgical repair of perinasal skin defects

Immediate reconstruction of full-thickness skin defects after cancer surgery is a commonly accepted surgical principle used to preserve function and minimize cosmetic deformity. Healing by secondary intention, however, offers the advantages of optimal cancer surveillance, simplified wound management, and avoidance of reconstructive procedures with their associated costs and potential complications. Accurate prediction of the course of wound healing, and thereby the final functional and cosmetic result, would allow a rational approach to selection of patients for surgical or nonsurgical repair. We observed 282 patients with full-thickness perinasal (glabella, medial canthus, dorsum, sidewall, tip, ala, philtrum, alar base, and nasolabial fold) skin defects after Mohs' surgery and documented a variety of parameters affecting wound healing, including location, depth, and size of the wound. Patients were examined at intervals, and a final determination regarding cosmesis and function was made at 6 months or later. We conclude that the most important considerations in predicting the final functional and cosmetic result include location by subunit, followed by size and depth of the wound.     

Carbon and oxygen isotope geochemistry of live (stained) benthic foraminifera from the Aleutian Margin and the Southern Australian Margin

Comparisons of ambient bottom-water geochemistry and stable isotopic values of the tests of living (stained) calcareous benthic foraminifera from the North Pacific (on the Aleutian Margin, water depth 1988 m) and Murray Canyons group in the Southern Indian Ocean (Australian Margin, water depths 2476 m and 1634 m) provide modern environmental analogs to calibrate paleoenvironmental assessments. Consistent with the hypothesis that microhabitat preferences influence foraminiferal isotopic values, benthic foraminifera from both margins were depleted in ¹³C with respect to bottom-water dissolved inorganic carbon (DIC). The carbon isotope values of deep infaunal foraminifera (Chilostomella oolina, Globobulimina pacifica) showed greater differences from estimates of those of DIC than shallow benthic foraminifera (Bulimina mexicana, Bolivinita quadrilatera, Pullenia bulloides). This study provides new isotopic and ecological information for B. quadrilatera. The mean Δδ¹³C value, defined as foraminiferal δ¹³C values minus estimated ambient δ¹³C values from the Aleutian Margin, is 0.97‰ higher for G. pacifica than the mean from the Murray Canyon. This difference may result either from genetic or biological differences between the populations or from differences in environmental isotopic influences (such as pore water differences) that were not accounted for in the equilibrium calculations. These analyses provide calibration information for the evaluation of bottom water conditions and circulation patterns of ancient oceans based on fossil foraminiferal geochemistry.     

A note on difference-delay equations.

Populations that obey differential-delay equations, and those that obey ordinary first-order difference equations, may be understood within a common general framework, wherein excessive time lags lead to stable limit cycle behavior. This note extends the analysis to include difference-delay equations (i.e., nonoverlapping generations with explicit time lags in the density dependent regulatory mechanisms).     

Towards understanding the glycoprotein hormone receptors.

Lutropin (LH), follitropin (FSH) and thyrotropin (TSH), as well as choriogonadotropin (CG, which binds to the LH receptor) constitute the glycoprotein hormone family. Their 3 receptors have been cloned during the last few months. They belong to the large group of G-protein coupled membrane proteins, with their specific N-terminal domain likely to bind the hormone and the characteristic 7 membrane-spanning segments in their C-terminal moiety. The present review discusses the main results of amino acid sequence analysis performed on the glycoprotein hormone receptors. The putative extracellular head exhibits less than 45% homology over the 3 receptors, while approximately 70% residue conservation is found in the transmembrane moiety. Here only, limited sequence homologies (approximately 20%) can be found with other G-protein coupled receptors. The secondary structure predictions performed on the 3 receptors revealed that the polypeptide sequence predicted as ordered (either alpha-helix or beta-strand) were repeated evenly throughout the extracellular head with a period of approximately 25 amino acids. This analysis helped to define the intervening loops between this ordered stretches as potential candidates for bearing at least part of the binding site of the hormones. Some of the perspectives opened by the cloning of the receptors are described, like the production of the extracellular head of the porcine LH receptor in baculovirus-infected insect cells, and the exploration of the LH receptor's mechanism of functioning as a dimer.