Conformational states of Leu5- and Met5-enkephalins in solution

The molecular conformations of Leu5- and Met5-enkephalins in aqueous and DMSO solutions were investigated by FT-IR and laser Raman spectroscopic methods. The amide I, II, and III regions in the FT-IR spectra of Leu5- and Met5-enkephalins in aqueous solution were analyzed by performing Fourier self-deconvolution of the bands. Leu5-enkephalin in aqueous solution is found to exist in both type II beta-turn and beta-sheet structures, whereas Met5-enkephalin has a lesser tendency to form beta-turn structure in aqueous solution. It is likely that these different conformers of enkephalins might bind to different receptor types.     

Modulation of the Acetylcholine System in the Superior Cervical Ganglion of Rat: Effects of GABA and Hypoglossal Nerve Implantation After In Vivo GABA Treatment

gamma-Aminobutyric acid (GABA) was applied to the superior cervical ganglion (SCG) of CFY rats in vitro and in vivo, with or without implantation of a hypoglossal nerve, to evaluate the effects of these experimental interventions on the acetylcholine (ACh) system, which mainly serves the synaptic transmission of the preganglionic input. Long-lasting GABA microinfusion into the SCG in vivo apparently resulted in a "functional denervation." This treatment reduced the acetylcholinesterase (AChE; EC 3.1.1.7) activity by 30% (p less than 0.01) and transiently increased the number of nicotinic acetylcholine receptors, but had no significant effect on the choline acetyltransferase (acetyl-coenzyme A:choline-O-acetyltransferase; EC 2.3.1.6) activity, the ACh level, or the number of muscarinic acetylcholine receptors. The relative amounts of the different molecular forms of AChE did not change under these conditions. In vivo GABA application to the SCG with a hypoglossal nerve implanted in the presence of intact preganglionic afferent synapses exerted a significant modulatory effect on the AChE activity and its molecular forms. The "hyperinnervation" of the ganglia led to increases in the AChE activity (to 142.5%, p less than 0.01) and the 16S molecular form (to 200%, p less than 0.01). It is concluded that in vivo GABA microinfusion and GABA treatment in the presence of additional cholinergic synapses has a modulatory effect on the elements of the ACh system in the SCG of CFY rats.     

Variation in mitochondrial DNA in a cline of allele frequencies and shell phenotype in the dog-whelk Nucella lapillus (L.)

Genetic constitution in the intertidal gastropod Nucella lapillus (L.) influences shell shape, growth rate and physiology. Clinal variation in these traits along a 5 km stretch of coastline in south Devon can be related to environmental variation in temperature and desiccation stress. We have examined mtDNA variation along this shore to investigate whether the cline represents primary or secondary contact. Two distinct mtDNA haplotypes were found which exhibit coincident step clines with karyotypic, allozymic and phenotypic variation and covary with the environmental pressures of temperature and desiccation. These results are interpreted in the context of the wider scale distribution of genetic and phenotypic variation in N. lapillus. It is suggested that the shore studied may represent one of a number of regions of secondary contact within a mosaic hybrid zone in N. lapillus , where coadapted phenotypic variation correlates with habitat and the position of the clines represents an environmental transition.     

Drosophila wing modularity revisited through a quantitative genetic approach

To predict the response of complex morphological structures to selection it is necessary to know how the covariation among its different parts is organized. Two key features of covariation are modularity and integration. The Drosophila wing is currently considered a fully integrated structure. Here, we study the patterns of integration of the Drosophila wing and test the hypothesis of the wing being divided into two modules along the proximo‐distal axis, as suggested by developmental, biomechanical, and evolutionary evidence. To achieve these goals we perform a multilevel analysis of covariation combining the techniques of geometric morphometrics and quantitative genetics. Our results indicate that the Drosophila wing is indeed organized into two main modules, the wing base and the wing blade. The patterns of integration and modularity were highly concordant at the phenotypic, genetic, environmental, and developmental levels. Besides, we found that modularity at the developmental level was considerably higher than modularity at other levels, suggesting that in the Drosophila wing direct developmental interactions are major contributors to total phenotypic shape variation. We propose that the precise time at which covariance‐generating developmental processes occur and/or the magnitude of variation that they produce favor proximo‐distal, rather than anterior‐posterior, modularity in the Drosophila wing.     

Combination of Bioactive Polymeric Membranes and Stem Cells for Periodontal Regeneration: In Vitro and In Vivo Analyses

Regeneration of periodontal tissues requires a concerted effort to obtain consistent and predictable results in vivo. The aim of the present study was to test a new family of bioactive polymeric membranes in combination with stem cell therapy for periodontal regeneration. In particular, the novel polyester poly(isosorbide succinate-co-L-lactide) (PisPLLA) was compared with poly(L-lactide) (PLLA). Both polymers were combined with collagen (COL), hydroxyapatite (HA) and the growth factor bone morphogenetic protein-7 (BMP7), and their osteoinductive capacity was evaluated via in vitro and in vivo experiments. Membranes composed of PLLA/COL/HA or PisPLLA/COL/HA were able to promote periodontal regeneration and new bone formation in fenestration defects in rat jaws. According to quantitative real-time polymerase chain reaction (qRT-PCR) and Alizarin Red assays, better osteoconductive capacity and increased extracellular mineralization were observed for PLLA/COL/HA, whereas better osteoinductive properties were associated with PisPLLA/COL/HA. We concluded that membranes composed of either PisPLLA/COL/HA or PLLA/COL/HA present promising results in vitro as well as in vivo and that these materials could be potentially applied in periodontal regeneration.     

Structural and functional differentiation of two clinally distributed glucosephosphate isomerase allelic isozymes from the teleost Fundulus heteroclitus

The teleost Fundulus heteroclitus (L.) possesses two loci, Gpi-A and Gpi-B, for the glycolytic enzyme, glucose-phosphate isomerase (GPI; D- glucose-6-phosphate ketol-isomerase; E.C. 5.3.1.9). The Gpi-B locus is polymorphic in Fundulus, with two common alleles, Gpi-Bb and Gpi-Bc, distributed in a clinal manner in populations along the east coast of North America. Since this clinal distribution is strongly correlated with a temperature gradient, we asked whether the GPI-B2 allozymes were functionally adapted to the thermal environment in which a given phenotype predominated. The two major GPI-B2 allozymes were purified to homogeneity and were characterized as to molecular weight, isoelectric pH, thermal denaturation, and kinetic parameters. Both GPI-Bb2 and GPI- Bc2 allozymes have molecular masses of 110 kD, and they have isoelectric pHs of 6.4 and 6.6, respectively. The GPI-Bb2 allozyme was more stable to thermal denaturation than was the GPI-Bc2 enzyme. Kinetic properties of the allelic isozymes were investigated both as a function of pH and as a function of temperature. At 25 degrees C, over the pH range considered, there were no significant differences between allozymes, either in Km for fructose-6-phosphate or in Ki for 6- phosphogluconate, but apparent Vmax values differed between pH 7.5 and pH 8.5. All steady-state kinetic parameters showed strong temperature dependence, but the allozymes differed only in the Ki for 6- phosphogluconate at temperatures greater than 30 degrees C. On the basis of the observed structural and functional differences alluded to above, the hypothesis that the major allelic isozymes of the Gpi-B locus were functionally equivalent was rejected. However, it is not yet known whether these structural and functional differences have any significance at higher levels of biological organization.      

Echocardiographic assessment and percutaneous closure of multiple atrial septal defects

Percutaneous coronary intervention can be associated with distal embolization of thrombotic material causing myocardial necrosis and infarction. We discuss the role of intravascular imaging to guide the use of a distal protection device by describing the outcome of a young woman presenting with non-ST elevation myocardial infarction. Coronary angiography demonstrated an isolated minor stenosis in the proximal left anterior descending coronary artery with slight haziness beyond the lesion. Intravascular ultrasound confirmed an extensive thrombus overlying a bulky atherosclerotic plaque. A distal filter wire was therefore successfully used to reduce the risk of distal embolization. The use of intravascular ultrasound in patients presenting with acute coronary syndrome may reveal large thrombi that are difficult to image using conventional angiographic techniques. Intravascular ultrasound can therefore be used as a tool to select lesions requiring distal protection.