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Abstract: The effect of functional mitral regurgitation has been investigated in an anatomically sized, fluid–structure interaction mitral valve model, where simulated correction has been performed by applying: (1) edge-to-edge repair with annuloplasty and (2) edge-to-edge repair only. Initially defined in an open unstressed/corrected configuration, fluid–structure interaction simulations of diastole have been performed in a rigid ventricular volume. Comparison of the maximum principal stresses (during diastole) in the normal and repaired models has shown that the magnitude of stress in the repaired scenarios is greater. The combined edge-to-edge and annuloplasty procedure was found to spread the induced stresses across the free margin of the leaflets, whereas without annuloplasty a localised stress concentration in the region of the suture was observed. Fluid flow downstream of the corrected configurations was able to achieve the same magnitude as in the normal case, although the flow rate was impaired. The maximum flow rate was found to be reduced by 44–50% with the peak flow rate shifted from the end of the diastole in the normal case to the start in the repaired cases. [Copyright &y& Elsevier]

Tbx1 is a member of the Tbox family of binding domain transcription factors. TBX1 maps within the region of chromosome 22q11 deleted in humans with DiGeorge syndrome (DGS), a common genetic disorder characterized by numerous physical manifestations including craniofacial and cardiac anomalies. Mice with homozygous null mutations in Tbx1 phenocopy this disorder and have defects including abnormal cranial ganglia formation and cardiac neural crest cell migration. These defects prompted us to investigate whether extrinsic vagus nerve or intrinsic enteric nervous system abnormalities are prevalent in the gastrointestinal tract of Tbx1 mutant mice. We used in situ hybridization for Ret, and immunohistochemical staining for neurofilament, HuC/D and βIII-tubulin to study cranial ganglia, vagus nerve, and enteric nervous system development in Tbx1 mutant and control mice. In Tbx1 embryos, cranial ganglia of the glossopharyngeal (IXth) and vagus (Xth) nerves were malformed and abnormally fused. In the gastrointestinal tract, the vagus nerves adjacent to the esophagus were severely hypoplastic and they did not extend beyond the gastro-esophageal junction nor project branches within the stomach wall, as was observed in Tbx1 mice. Although cranial ganglia morphology appeared normal in Tbx1 mice, these animals had a spectrum of stomach vagus innervation defects ranging from mild to severe. In all Tbx1 genotypes, the intrinsic enteric nervous system developed normally. The deficit in vagal innervation of the stomach in mice mutant for a gene implicated in DGS raises the possibility that similar defects may underlie a number of as yet unidentified/unreported congenital disorders affecting gastrointestinal function. [ABSTRACT FROM AUTHOR]

Abstract: Modelling and simulation of heart valves is a challenging biomechanical problem due to anatomical variability, pulsatile physiological pressure loads and 3D anisotropic material behaviour. Current valvular models based on the finite element method can be divided into: those that do model the interaction between the blood and the valve (fluid–structure interaction or ‘wet’ models) and those that do not (structural models or ‘dry’ models). Here an anatomically sized model of the mitral valve has been used to compare the difference between structural and fluid–structure interaction techniques in two separately simulated scenarios: valve closure and a cardiac cycle. Using fluid–structure interaction, the valve has been modelled separately in a straight tubular volume and in a U-shaped ventricular volume, in order to analyse the difference in the coupled fluid and structural dynamics between the two geometries. The results of the structural and fluid–structure interaction models have shown that the stress distribution in the closure simulation is similar in all the models, but the magnitude and closed configuration differ. In the cardiac cycle simulation significant differences in the valvular dynamics were found between the structural and fluid–structure interaction models due to difference in applied pressure loads. Comparison of the fluid domains of the fluid–structure interaction models have shown that the ventricular geometry generates slower fluid velocity with increased vorticity compared to the tubular geometry. In conclusion, structural heart valve models are suitable for simulation of static configurations (opened or closed valves), but in order to simulate full dynamic behaviour fluid–structure interaction models are required. [ABSTRACT FROM AUTHOR]

The inherited genetic defect in adenomatous polyposis has been localized to a small region on the long arm of chromosome 5. Sixteen DNA marker loci were used to construct a linkage map of the chromosome. When five kindreds segregating a gene for adenomatous polyposis coli were characterized with a number of the markers, significant linkage was found between one marker and the disease gene. Linkage analysis determined the location of the defective gene within a primary genetic map of chromosome 5. [ABSTRACT FROM AUTHOR]

Unlabelled: Most cases of sacral dysgenesis are considered to be sporadic events. We present two families in whom the presence of associated clinical features prompted specific investigation of chromosome 7, leading to the identification of an underlying chromosome 7q deletion causing sacral dysgenesis. All affected individuals had microcephaly and developmental delay. Detailed cytogenetic studies confirmed that all three affected individuals had a deletion of chromosome 7q associated with their sacral dysgenesis, developmental delay and related problems. The three affected patients were studied clinically, radiologically and cytogenetically. Eleven unaffected individuals from the two families were also investigated by genetic studies, specifically evaluating chromosome 7.Conclusion: It is important that detailed family history, evaluation of associated malformations and the overall clinical picture be considered in identifying the underlying diagnosis in cases of anal stenosis/sacral agenesis. The cases we present demonstrate the value of detailed chromosome studies in such situations. [ABSTRACT FROM AUTHOR]

An abstract of the article "Increased nuchal translucency origins from abnormal lymphatic development and develops regardless of the presence of a congenital heart defect" by N. Burger and colleagues is presented.

Presents a corrected reprint to an article previously published in the 2000 issue of the journal 'Clinical Endocrinology.'

Examines the embryonic expression of the HLXB9 currarino syndrome gene. Effect of missense mutations on patient condition; Proposal of a notochordal defect in the tail bud; Implication of the HLXB9 expression on the developing gut.

Comments on the relation of human genes on diseases. Mutation of TIGR/MYOC gene in primary open-angle glaucoma; Evidence for genetic heterogeneity of nephrophatic phenotypes associated with denys-drash and Frasier syndrome; Study on Rett syndrome in a boy with 47,XXy karyotype.