In situ ATR-FTIR characterization of primary cement interfaces of the barnacle Balanus amphitrite.

A method is presented for characterizing primary cement interfaces of barnacles using in situ attenuated total reflection-Fourier transform infrared spectroscopy. Primary cement of the barnacle, Balanus amphitrite (Amphibalanus amphitrite), was characterized without any disruption to the original cement interface, after settling and growing barnacles directly on double sided polished germanium wafers. High-quality IR spectra were acquired of live barnacle cement interfaces, providing a spectroscopic fingerprint of cured primary cement in vivo with the barnacle adhered to the substratum. Additional spectra were also acquired of intact cement interfaces for which the upper portion of the barnacle had been removed leaving only the base plate and cement layer attached to the substratum. This allowed further characterization of primary cement interfaces that were dried or placed in D(2)O. The resulting spectra were consistent with the cement being proteinaceous, and allowed analysis of the protein secondary structure and water content in the cement layer. The estimated secondary structure composition was primarily beta-sheet, with additional alpha-helix, turn and unordered components. The cement of live barnacles, freshly removed from seawater, was estimated to have a water content of 20-50% by weight. These results provide new insights into the chemical properties of the undisturbed barnacle adhesive interface.

Barnacle reattachment: a tool for studying barnacle adhesion.

Standard approaches for measuring adhesion strength of fouling organisms use barnacles, tubeworms or oysters settled and grown in the field or laboratory, to a measurable size. These approaches suffer from the vagaries of larval supply, settlement behavior, predation, disturbance and environmental stress. Procedures for reattaching barnacles to experimental surfaces are reported. When procedures are followed, adhesion strength measurements on silicone substrata after 2 weeks are comparable to those obtained using standard methods. Hydrophilic surfaces require reattachment for 2-4 weeks. The adhesion strength of barnacles in reattachment assays was positively correlated to results obtained from field testing a series of experimental polysiloxane fouling-release coatings (r = 0.89). The reattachment method allows for precise barnacle orientation, enabling the use of small surfaces and the potential for automation. The method enables down-selection of coatings from combinatorial approaches to manageable levels for definitive field testing. Reattachment can be used with coatings that combine antifouling and fouling-release technologies.

Utilidad de la tomografia computada del cerebro en neonatologia. / Usefulness of computerizes tomography of the brain in neonatology

Se analizan 17 estudios de tomografia computada del cerebro (TCC), practicados a recien nacidos, descubriendose un elevado indice de hallazgos negativos que se atribuyen a la falta de un criterio adecuado para indicar el procedimiento; esto eleva la relacion costo-eficiencia desvirtuando el beneficio del procedimiento como recurso diagnostico. Se concluye que en neonatologia la TCC debe ser empleada como una modalidad secundaria de apoyo diagnostico y no como primaria diagnostica, dado que la pretension de obtener hallazgos positivos no debe basarse en inferir dano cerebral por la aparicion de manifestaciones cuya relacion causal puede ser multifactorial