The present study deals with the experimental analysis and mechanical modeling of tensile behavior of brain soft tissue. A transversely isotropic hyperelastic model recently proposed by Meaney (2003) is adopted and mathematically studied under uniaxial loading conditions. Material parameter estimates are obtained through tensile tests on porcine brain materials accounting for regional and directional differences. Attention is focused on the short-term response. An extrapolation of tensile test data to the compression range is performed theoretically, to study the effect of the heterogeneity in the tensile/compressive response on the material parameters. Experimental and numerical results highlight the sensitivity of the adopted model to the test direction.

The results of an international multicenter study concerning the first complication of newly implanted cerebrospinal fluid shunts in nontumoral hydrocephalus are the subject of the present report. The authors have collected information on 773 cases from four continents. In particular, the following data were evaluated in relation to the general incidence of complications recorded in the first follow-up year: the patient's age at the operation, the etiology of hydrocephalus, the type of CSF shunt device used, and the modality of the surgical procedures. The overall complication rate in the series was 29%. Age and etiology of hydrocephalus appear to play a major role in influencing the complication rate; on the other hand, the choice of a specific CSF shunt device seems to be less important in this respect.

Craniosynostoses are a heterogeneous group of disorders characterized by premature fusion of cranial sutures. Mutations in fibroblast growth factor receptors (FGFRs) have been associated with a number of such conditions. Nevertheless , the cellular mechanism(s) involved remain unknown. We analyzed cell proliferation and differentiation in osteoblasts obtained from patients with three genetically and clinically distinct craniosynostoses: Pfeiffer syndrome carrying the FGFR2 C342R substitution , Apert syndrome with FGFR2 P253R change , and a nonsyndromic craniosynostosis without FGFR canonic mutations , as compared with control osteoblasts. Osteoblasts from craniosynostotic patients exhibited a lower proliferation rate than control osteoblasts. P253R and nonsyndromic craniosynostosis osteoblasts showed a marked differentiated phenotype, characterized by high alkaline phosphatase activity, increased mineralization and expression of noncollagenous matrix proteins , associated with high expression and activation of protein kinase C␣ and protein kinase C⑀ isoenzymes. By contrast , the low proliferation rate of C342R osteoblasts was not associated with a differentiated phenotype. Although they showed higher alkaline phosphatase activity than control , C342R osteoblasts failed to mineralize and expressed low levels of osteopontin and osteonectin and high protein kinase C levels. Stimulation of proliferation and inhibition of differentiation were observed in all cultures on FGF2 treatment. Our results suggest that an anticipated proliferative/differentiative switch , associated with alterations of the FGFR transduction pathways , could be the causative com- Craniosynostosis, the premature ossification of one or more sutures of the flat bones of the developing skull, is a relatively common defect of the cranial morphogenetic program, with a prevalence at birth of approximately 1:3000. It results in a wide spectrum of craniofacial anomalies, including abnormal head shape, protruding eyes, and midface underdevelopment.

Jackson-Weiss syndrome is a rare skeletal disorder characterized by craniosynostosis associated with foot malformations. This condition is inherited as an autosomal dominant trait with complete penetrance and wide phenotypic heterogeneity. Mutations in the fibroblast growth factor receptor 2 (FGFR2) gene have been recently identified as causes of this syndrome and of at least four other craniosynostotic disorders, namely the Apert, Beare-Stevenson cutis gyrata, Crouzon and Pfeiffer syndromes. We report two novel FGFR2 missense mutations associated with phenotypes consistent with Jackson-Weiss syndrome. Both nucleotide changes predict a serine for cysteine-342 substitution in the second half of the third immunoglobulin-like domain. The replacement of Cys342 with arginine has previously been reported in one of the three Jackson-Weiss cases investigated. Interestingly, both Cys342Ser and Cys342Arg substitutions have been found to be associated with the Crouzon and Pfeiffer phenotypes; a phenotypic heterogeneity, Crouzon vs Jackson-Weiss clinical features, has been also observed for Gln289Pro and Ala344Gly amino-acid changes. This finding indicates the genetic homogeneity of the "heterogeneous" Jackson-Weiss phenotype and a common molecular basis for these apparently "clinically distinct" craniosynostotic disorders.