Review of biomechanical models used in studying the biomechanics of reconstructed mandibles.

This study looked at computer and physical biomodels used to study the biomechanical performance of mandibular reconstruction, reviews the literature and explains the strengths and limitations of the models. Electronic databases (Pubmed, Medline) were searched. 17 articles were selected. Computer biomodels can be divided into virtual biomodels (mainly used for clinical diagnosis and treatment planning) and computational models (e.g. finite element analysis), they can predict areas most likely to fail based on internal stress distribution and areas of maximum stress concentration. Physical biomodels include: rapid prototyping, animal bone, human cadaveric bone, and bone substitute models. Physical models allow testing on a gross level to give fatigue performance and fracture strength. The use of bone substitutes allows a more consistent specimen size and a reduction in sample size. Some commercially available products can replicate the material properties of bone. The use of any biomodel depends on the question being asked: the bending strength of a reconstruction plate would necessitate a three point bending test; the biomechanical performance of a new method of reconstruction (e.g. the mandibular modular endoprosthesis) would necessitate finite element analysis to predict areas of likely failure and also a physical biomodel to look at fatigue failure.

On the effect of tastant excluded fillers on sweetness and saltiness of a model food.

In this study, the effect on taste due to the addition of air bubbles to a water-based gel was investigated. The gel phase contained either sucrose to give a sweet taste or sodium chloride to give a salty taste. For the sweet gels, taste intensities were evaluated for samples with different volume fractions of the air bubbles (up to 40%, v/v) and different concentrations of the sucrose. For the salty gels, samples were evaluated at 40% volume fraction of air bubbles. It was found that a reduction of the sodium chloride or sucrose by the same weight percentage as the volume fraction of the air bubbles in the samples gave equal taste perception as the nontastant-reduced samples. Moreover, saltiness and sweetness perception were clearly enhanced at 40% volume fractions of air bubbles if the sodium chloride or sucrose was not reduced. Thus, the overall tastes of the samples appeared to depend mainly on the concentration levels of the salt or the sucrose in the aqueous phase irrespective of the volume fraction of the air bubbles. However, the air bubbles were found to change the texture and appearance of the samples. It has been demonstrated that the inclusion of air bubbles offers scope for the reduction of sodium chloride or sucrose in food products.

Minimal access approach to the management of large ovarian cysts.

Laparoscopy has become an accepted method of management for ovarian cysts. Large ovarian cysts, however, have traditionally been, and continue to be treated by laparotomy. This is mainly due to technical difficulties and the possibility of malignancy. We describe four patients in whom laparoscopy was used to remove large ovarian cysts. Laparoscopic guided aspiration was performed, followed by extra-abdominal excision of the cyst. This approach has the advantages of minimising the risk of spillage of cyst fluid, a smaller incision compared to laparotomy, as well as faster recovery. We advocate this method for large unilocular benign cysts.

Segmentation induced by intraluminal fatty acid in isolated guinea-pig duodenum and jejunum.

Small intestinal movements depend on the composition of the chyme with mixing predominating at high nutrient levels and propulsion being prevalent at low nutrient levels. The mechanisms coupling nutrients to motility are unknown. We used computer analysis of video recordings of isolated guinea-pig duodenum, jejunum and ileum to examine movements induced by a fatty acid, decanoic acid. Increasing intraluminal pressure past a threshold using control saline consistently evoked propulsive reflexes: lumen-occluding constrictions appeared at the oral end propagating at 20.4 +/- 2.4 mm s(-1) (mean +/-s.d., jejunum) to the anal end before being repeated until the intraluminal pressure was returned to control. Subthreshold pressure increases sometimes evoked a transient series of constrictions appearing at the oral end and propagating anally at 18.4 +/- 4.7 mm s(-1) (jejunum). At basal pressures, decanoic acid dose-dependently induced motor activity consisting of 40-60 s episodes of constrictions separated by 40-200 s periods of quiescence and lasting up to 2 h. Five contraction patterns were identified within episodes including localized stationary constrictions; constrictions that propagated slowly (5-8 mm s(-1)) for short distances orally or anally; and constrictions that propagated orally or anally for the length of the preparation at 14-20 mm s(-1). Decanoic acid induced motor activity was reversibly abolished by tetrodotoxin (3 microm), hyoscine (1 microm) and hexamethonium (100 microm), but was insensitive to blockade of P2 purinoceptors by PPADS (60 microm). Thus, decanoic acid induces motor activity equivalent to segmentation in guinea-pig small intestine in vitro and this depends on intrinsic neural pathways.