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The American Society of Anesthesiologists difficult airway algorithm identifies two acceptable emergency surgical airways in the 'cannot intubate, cannot ventilate' scenario: cricothyrotomy and tracheotomy. Little has been published regarding the emergency surgical airway practices at different institutions. The authors investigated whether the primary choice of emergency surgical airway at a major level I trauma centre was cricothyrotomy or tracheotomy. A retrospective chart review was conducted of emergency airways performed over 6 years using relevant current procedural terminology codes. The electronic medical records obtained were reviewed to ensure accurate coding and verify the emergent nature of the procedure. Over the study period, there were 4312 documented emergent airways. 3197 (74.1%) were field intubated by paramedics, 1081 (25.1%) were hospital intubated by anaesthesia, 34 (0.008%) required emergency surgical access of which 24 were tracheotomies and 10 cricothyrotomies. Despite the emphasis in resident training and Advanced Trauma Life Support, there was a paucity of cricothyrotomies during the study period. At the authors' institution, tracheotomy is preferentially used as the emergency surgical airway. A multicentre prospective study is recommended to evaluate current practice in emergency surgical airway and to include the emergency open tracheotomy in residency training and continuing education if needed.

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BACKGROUND: Intestinal atresia represents a significant surgically correctable cause of intestinal obstruction in neonates. Intestinal development proceeds as a tube-like structure with differentiation along its axis. As the intestine differentiates, the cecum develops at the transition from small to large intestine. Fgf10 is known to serve a key role in budding morphogenesis; however, little is known about its role in the development of this transitional structure. Here we evaluate the effect of Fgf10/Fgfr2b invalidation on the developing cecum. MATERIALS AND METHODS: Wild-type C57Bl/6, Fgf10(-/-), and Fgfr2b(-/-) embryos harvested from timed pregnant mothers were analyzed for cecal phenotype, Fgf10 expression, and differentiation of smooth muscle actin. RESULTS: Wt cecal development is first evident at E11.5. FGF10 is discreetly expressed in the area of the developing cecum at early stages of development. One hundred percent of Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with absence of epithelial and muscular layers. The development of neighboring anatomical structures such as the ileocecal valve is not affected by Fgf10/Fgfr2b invalidation. CONCLUSIONS: FGF10 expression is localized to the cecum early in the normal development of the cecum. Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with complete penetrance. Epithelial and muscular layers of the cecum are not present in the atretic cecum. The Fgf10(-/-) and Fgfr2b(-/-) mutants represent a genetically reproducible animal model of autosomal recessive intestinal atresia.

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Epithelial-mesenchymal interactions are critical for the formation of gastrointestinal buds such as the cecum from the midgut, but the mechanisms regulating this process remain unclear. To investigate this problem, we have studied the temporal and spatial expression of key genes known to orchestrate branching morphogenesis. At E10.5, Fibroblast growth factor 10 (Fgf10) is specifically expressed in the mesenchyme above the future cecal epithelial bud, whereas Fgfr2b is found throughout the gut epithelium. From E11.5 onwards, Fgf10 expression is found throughout the cecum mesenchyme. Other relevant signaling molecules such as Sonic hedgehog, Wnt2b, and Tbx4 transcripts are found throughout the gut epithelium, including the cecum. Epithelial expression is also seen for Sprouty2, but only from E14.5 onwards. By contrast, Bone morphogenetic 4 (Bmp4) and Pitx2 are specifically expressed in the mesenchyme of the cecal bud at E11.5. Abrogation of either Fgf10 or Fgfr2b leads to similar phenotypes characterized by an arrest of epithelial invasion into the cecal mesenchymal tissue. However, a bud of undifferentiated cecal mesenchymal tissue is maintained throughout development. Our results further indicate that mesenchymal FGF10 acts mostly through the epithelial FGFR2b receptor; thereby triggering invasion of the midgut epithelium into the adjacent mesenchyme via an increased rate of epithelial proliferation at the tip of the cecum. Thus, FGF10 signaling via FGFR2b appears to be critical in the extension of the epithelium into the mesenchyme during cecal development.

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Seoh & Busath (1995) showed that in the presence of formamidinium, single gramicidin A channels were lengthened, had uniformly noisy currents at low voltages and had superlinear current-voltage relationships, all three properties being absent in gramicidin M- channels in which the interfacial tryptophan residues in gramicidin A are all replaced by phenylalanine. We measured the single channel noise power spectra (PSDs) in small monoolein (GMO) bilayers with formamidinium chloride solutions to help identify the mechanism of noise process. PSDs were Lorentzian with characteristic frequencies of 0.1-1.0 kHz in 0.1 and 0.3 M formamidinium chloride solutions, and from. 1-6 kHz in 1 M solution. Si(0), where measurable, ranged from approximately 50-200 fA2/Hz. The time course of the noise process could not be detected in these experiments. The low fc suggests slow motions or rare states of the blocking 'gates' which, judging from the result with gramicidin M-, must be equal to or related to the Trp residues.

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We have evaluated a new solid phase enzyme immunoassay (EIA) for detection of terminal deoxynucleotidyl transferase (TDT). The EIA is greater than 100 times more sensitive than previously used tests for enzyme activity. In 284 clinical specimens of human peripheral blood and bone marrow, the EIA detected TdT antigen in 97% of peripheral blood and 100% of bone marrow samples that were positive for enzymatic activity. The excellent sensitivity and specificity of this new test suggests that it can be used in clinical situations where quantitative TdT measurements are desired.

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The determination of lymphocyte subpopulations is becoming increasingly useful in the clinical laboratory. Defining cells beyond the T- and B-lymphocyte level is now possible and with improved technology such as double labeling, histochemical stains, and cytofluorographic analysis, lymphocyte subpopulation identification will become more routine. This overview presents the current status of the art of defining lymphocyte subpopulations and its usefulness in clinical medicine.

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A simple, inexpensive, and easily visible procedure for labeling phagocytic cells in B-cell preparations is discussed. The procedure involves adding rhodamine-latex particles to lymphocyte preparations, then simultaneously looking for the presence of ingested latex particles in contaminating phagocytic cells and for fluorescein labeled surface immunoglobulins. This differentiation of cells allows one to correct for the true percentage of B cells.

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