Shape morphology of dipolar domains in planar and spherical monolayers.

We present a continuum theory for predicting the equilibrium shape and size of dipolar domains formed during liquid-liquid phase coexistence in planar and spherical monolayers. Our main objective is to assess the impact of the monolayer surface curvature on domain morphology. Following previous investigators, we base our analysis around minimizing the free energy, with contributions from line tension and electrostatic dipolar repulsions. Assuming a monodisperse system of circularly symmetric domains, we calculate self-energies and interaction energies for planar and spherical monolayers and determine the equilibrium domain size from the energy minima. We subsequently evaluate the stability of the circularly symmetric domain shapes to an arbitrary, circumferential distortion of the perimeter via a linear stability analysis. We find that the surface curvature generally promotes the formation of smaller, circularly symmetric domains instead of larger, elongated domains. We rationalize these results by examining the effect of the curvature on the intra- and inter-domain dipolar repulsions. We then present a phase diagram of domain shape morphologies, parameterized in terms of the domain area fraction and the monolayer curvature. For typical domain dimensions of 1-30 µm, our theoretical results are relevant to monolayers (and possibly also bilayers) in liquid-liquid phase coexistence with radii of curvature of 1-100 µm.

[Treatment of tracheobronchomegaly with an Ultraflex prosthesis. A case report]. / Traitement de la trachéobronchomégalie par la mise en place d'une prothèse Ultraflex.

Tracheobronchomegaly is defined as a dilatation of the trachea and the large bronchi. It may occur as a familial condition or in association with a connective tissue disease, e.g. Ehlers-Danlos syndrome. Tracheobronchomegaly occurs late in adults. The predominant symptoms are bronchial irritation and recurrent bronchopulmonary infections (because of ineffective cough). Diagnosis is provided by thoracic imaging, particularly computed tomography that enables measuring the precise diameter of the trachea. We report the case of one patient with tracheobronchomegaly who was greatly improved after implantation of Ultraflex tracheobronchial prostheses.

Human intestinal anion exchanger isoforms: expression, distribution, and membrane localization.

A family of anion exchangers (AEs) including AE1, AE2 and AE3 has been described. AE3 gene has been shown to encode two alternatively spliced isoforms termed as bAE3 (brain subtype) and cAE3 (cardiac subtype). The identity of the AE(s) involved in the human intestinal NaCl absorption is not fully understood. Current studies were undertaken to identify the AE isoforms expressed in the human intestine, to define their regional and vertical axis (crypt vs. surface cells) distribution, and to elucidate their membrane localization in the epithelial cells along the entire length of the human intestine. Our studies utilizing reverse transcription (RT)-PCR with total RNA extracted from pinch biopsies from various regions of the human intestine demonstrate that AE2 and bAE3 but not AE1 or cAE3 were expressed in all the regions of the human intestine. Utilizing in situ RT-PCR, we demonstrated that the message of AE2 was expressed throughout the vertical surface--crypt axis of the colon. Our Western blotting studies demonstrated that AE2 and bAE3 are localized to the basolateral but not the apical membranes of the intestinal epithelial cells from the human ileum and colon. In conclusion, our results demonstrated that in the human intestine, AE2 and bAE3, but not AE1 or cAE3, are expressed throughout the tract with the highest expression in the colon compared to the ileum and jejunum. Both the isoforms were found to be localized to the basolateral but not the apical membranes of the epithelial cells. We speculate that, in the human intestine, AE2 and bAE3 may be the 'housekeeping' isoforms, and the apical AE, the potential candidate for chloride absorption, remains to be identified.

A cross-sectional prevalence study of the protozoan and helminth infections in school children 6-12 years of age in Grenada

Data on the public health importance of intestinal parasites in Grenada have not been available for over 60 years and this study aimed to redress this information gap. Between May and June 1999, a cross-sectional point prevalence study of intestinal protozoans and helminths was carried out in school children aged 6-12 years of age in three schools in St George's Parish, Grenada. After receiving informed consent, a single stool sample was obtained which was immediately aliquoted and samples stored in either the refrigerator or freezer. The refrigerator sample was processed by a salt flotation concentration technique. The frozen sample was analysed by ELISA assay for antigens of intestinal protozoa. A total of 315 samples was collected. For protozoans, prevalence rates of 36, 12 and 3 percent were obtained for Giardia lamblia, Entamoeba histolytica and Cryptosporidium parvum, respectively. For helminths, prevalence rates were 0.4, 1.3, 5.3 and 1.4 percent for hookworm, Enterobius vermicularis, Trichuris trichuria and Ascaris lumbricoides, respectively. Protozoans are prevalent in Grenadians school children but helminths are not as common. These differences in prevalence rates may reflect the easy availability of broad spectrum antihelmintics whilst drugs for protozoan infections are obtained by prescription only. The dramatic difference in the prevalence of intestinal helminths from earlier in the 20th century may also reflect a considerable improvement in the socio-economic status of the population. (Au)