PubMed Health⌕ Search

PubMed · 12085607

Intervertebral rotations as a function of rear impact loading.

Abstract

Rear impact loading of the cervical spine results in a complicated biomechanical problem due to the complex geometry and viscoclastic material properties of this anatomy. Although a number of investigations have been performed to understand the biomechanics of rear impact, the dependence of segmental kinematics on cervical level and input velocity has not been clearly outlined. An experimental investigation was performed for this purpose using 10 isolated head-neck specimens. Segmental motions of the cervical spine were obtained for levels C2-C3 to C6-C7 at rear impact velocities of 2.1, 4.6, 6.6, and 9.3 km/h. Increases in segmental motion from baseline kinematics were compared for the three higher velocity tests. Results indicated greater increase in magnitude of segmental motion for levels C5-C6 and C6-C7 at higher input velocities than all other investigated levels. This finding helps to define the kinematics of the cervical spine leading to whiplash injury.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Brian D Stemper, Narayan Yoganandan, Frank A Pintar. 2002. Intervertebral rotations as a function of rear impact loading.. https://pubmed.ncbi.nlm.nih.gov/12085607/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Molecular heterochrony and the evolution of sociality in bumblebees (Bombus terrestris).

Sibling care is a hallmark of social insects, but its evolution remains challenging to explain at the molecular level. The hypothesis that sibling care evolved from ancestral maternal care in primitively eusocial insects has been elaborated to involve heterochronic changes in gene expression. This elaboration leads to the prediction that workers in these species will show patterns of gene expression more similar to foundress queens, who express maternal care behaviour, than to established queens engaged solely in reproductive behaviour. We tested this idea in bumblebees (Bombus terrestris) using a microarray platform with approximately 4500 genes. Unlike the wasp Polistes metricus, in which support for the above prediction has been obtained, we found that patterns of brain gene expression in foundress and queen bumblebees were more similar to each other than to workers. Comparisons of differentially expressed genes derived from this study and gene lists from microarray studies in Polistes and the honeybee Apis mellifera yielded a shared set of genes involved in the regulation of related social behaviours across independent eusocial lineages. Together, these results suggest that multiple independent evolutions of eusociality in the insects might have involved different evolutionary routes, but nevertheless involved some similarities at the molecular level.

Analysis of Variance↗

Population structure and properties of Candida albicans, as determined by multilocus sequence typing.

We submitted a panel of 416 isolates of Candida albicans from separate sources to multilocus sequence typing (MLST). The data generated determined a population structure in which four major clades of closely related isolates were delineated, together with eight minor clades comprising five or more isolates. By Fisher's exact test, a statistically significant association was found between particular clades and the anatomical source, geographical source, ABC genotype, decade of isolation, and homozygosity versus heterozygosity at the mating type-like locus (MTL) of the isolates in the clade. However, these associations may have been influenced by confounding variables, since in a univariate analysis of variance, only the clade associations with ABC type and anatomical source emerged as statistically significant, providing the first indication of possible differences between C. albicans strain type clades and their propensity to infect or colonize different anatomical locations. There were no significant differences between clades with respect to distributions of isolates resistant to fluconazole, itraconazole, or flucytosine. However, the majority of flucytosine-resistant isolates belonged to clade 1, and these isolates, but not flucytosine-resistant isolates in other clades, bore a unique mutation in the FUR1 gene that probably accounts for their resistance. A significantly higher proportion of isolates resistant to fluconazole, itraconazole, and flucytosine were homozygous at the MTL, suggesting that antifungal pressure may trigger a common mechanism that leads both to resistance and to MTL homozygosity. The utility of MLST for determining clade assignments of clinical isolates will form the basis for strain selection for future research into C. albicans virulence.

Analysis of Variance↗