The relationship between lateral meniscus shape and joint contact parameters in the knee: a study using data from the Osteoarthritis Initiative

Introduction

The meniscus has an important role in force transmission across the knee, but a detailed three-dimensional (3D) morphometric shape analysis of the lateral meniscus to elucidate subject-specific function has not been conducted. The aim of this study was to perform 3D morphometric analyses of the lateral meniscus in order to correlate shape variables with anthropometric parameters, thereby gaining a better understanding of the relationship between lateral meniscus shape and its load-bearing function.

Methods

The lateral meniscus (LM) was manually segmented from magnetic resonance images randomly selected from the Osteoarthritis Initiative (OAI) non-exposed control subcohort. A 3D statistical shape model (SSM) was constructed to extract the principal morphological variations (PMV) of the lateral meniscus for 50 subjects (25 male and 25 female). Correlations between the principal morphological variations and anthropometric parameters were tested. Anthropometric parameters that were selected included height, weight, body mass index (BMI), femoral condyle width and axial rotation.

Results

The first principal morphological variation (PMV) was found to correlate with height (r = 0.569), weight (r = 0.647), BMI (r = 0.376), and femoral condyle width (r = 0.622). The third PMV was found to correlate with height (r = 0.406), weight (r = 0.312), and femoral condyle width (r = 0.331). The percentage of the tibial plateau covered by the lateral meniscus decreases as anthropometric parameters relating to size of the subject increase. Furthermore, when the size of the subject increases, the posterior and anterior horns become proportionally longer and wider.

Conclusion

The correlations discovered suggest that variations in meniscal shape can be at least partially explained by the levels of loads transmitted across the knee on a regular basis. Additionally, as the size of the subject increases and body weight rises, the coverage percentage of the meniscus is reduced, suggesting that there would be an increase in the load-bearing by the cartilage. However, this reduced coverage percentage is compensated by the proportionally wider and longer meniscal horn.     

Removing celiac disease-related gluten proteins from bread wheat while retaining technological properties: a study with Chinese Spring deletion lines

Background  

Gluten proteins can induce celiac disease (CD) in genetically susceptible individuals. In CD patients gluten-derived peptides are presented to the immune system, which leads to a CD4⁺ T-cell mediated immune response and inflammation of the small intestine. However, not all gluten proteins contain T-cell stimulatory epitopes. Gluten proteins are encoded by multigene loci present on chromosomes 1 and 6 of the three different genomes of hexaploid bread wheat (Triticum aestivum) (AABBDD).     

Development of Lactococcus lactis encoding fluorescent proteins,GFP, mCherry and iRFP regulated by the nisin-controlled gene expression system

Fluorescent proteins are useful reporter molecules for a variety of biological systems. We present an alternative strategy for cloning reporter genes that are regulated by the nisin-controlled gene expression (NICE) system. Lactoccocus lactis was genetically engineered to express green fluorescent protein (GFP), mCherry or near-infrared fluorescent protein (iRFP). The reporter gene sequences were optimized to be expressed by L. lactis using inducible promoter pNis within the pNZ8048 vector. Expression of constructions that carry mCherry or GFP was observed by fluorescence microscopy 2 h after induction with nisin. Expression of iRFP was evaluated at 700 nm using an infrared scanner; cultures induced for 6 h showed greater iRFP expression than non-induced cultures or those expressing GFP. We demonstrated that L. lactis can express efficiently GFP, mCherry and iRFP fluorescent proteins using an inducible expression system. These strains will be useful for live cell imaging studies in vitro or for imaging studies in vivo in the case of iRFP.     

Intraspecific DNA sequence variation of the mitochondrial control region of white sturgeon (Acipenser transmontanus)

Intraspecific sequence variation in the D-loop region of mtDNA in white sturgeon (Acipenser transmontanus), a relict North American fish species, was examined in 27 individuals from populations of the Columbia and Fraser rivers. Thirty-three varied nucleotide positions were present in a 462-nucleotide D-loop sequence, amplified using the polymerase chain reaction. Bootstrapped neighbor-joining and maximum- parsimony trees of sequences from 19 haplotypes suggest that the two populations have recently diverged. This is consistent with the hypothesis that the Columbia River, a Pleistocene refugium habitat, was the source of founders for the Fraser River after the last glacial recession. On the basis of a divergence time of 10-12 thousand years ago, the estimated substitution rate of the white sturgeon D-loop region is 1.1-1.3 x 10(-7) nucleotides/site/year, which is comparable to rates for hypervariable sequences in the human D-loop region. Furthermore, the ratio of mean percent nucleotide differences in the D- loop (2.27%) to that in whole mtDNA (0.54%, as estimated from restriction-enzyme data) is 4.3, which is similar to the fourfold-to- fivefold-higher substitution rate estimated for the human D-loop. The high nucleotide substitution rate of the hypervariable region indicates that the vertebrate D-loop has potential as a genetic marker in molecular population studies.      

Ancient large-scale genome duplications: phylogenetic and linkage analyses shed light on chordate genome evolution

Paralogous genes from several families were found in four human chromosome regions (4p16, 5q33-35, 8p12-21, and 10q24-26), suggesting that their common ancestral region underwent several rounds of large- scale duplication. Searches in the EMBL databases, followed by phylogenetic analyses, showed that cognates (orthologs) of human duplicated genes can be found in other vertebrates, including bony fishes. In contrast, within each family, only one gene showing the same high degree of similarity with all the duplicated mammalian genes was found in nonvertebrates (echinoderms, insects, nematodes). This indicates that large-scale duplications occurred after the echinoderms/chordates split and before the bony vertebrate radiation. It has been suggested that two rounds of gene duplication occurred in the vertebrate lineage after the separation of Amphioxus and craniate (vertebrates + Myxini) ancestors. Before these duplications, the genes that have led to the families of paralogous genes in vertebrates must have been physically linked in the craniate ancestor. Linkage of some of these genes can be found in the Drosophila melanogaster and Caenorhabditis elegans genomes, suggesting that they were linked in the triploblast Metazoa ancestor.      

Endogenous chloride channels of insect sf9 cells. Evidence for coordinated activity of small elementary channel units

The endogenous Cl- conductance of Spodoptera frugiperda (Sf9) cells was studied 20-35 h after plating out of either uninfected cells or cells infected by a baculovirus vector carrying the cloned beta-galactosidase gene (beta-Gal cells). With the cation Tris+ in the pipette and Na+ in the bath, the reversal potential of whole-cell currents was governed by the prevailing Cl- equilibrium potential and could be fitted by the Goldman-Hodgkin-Katz equation with similar permeabilities for uninfected and beta-Gal cells. In the frequency range 0.12 < f < 300 Hz, the power density spectrum of whole-cell Cl- currents could be fitted by three Lorentzians. Independent of membrane potential, >50% of the total variance of whole-cell current fluctuations was accounted for by the low frequency Lorentzian (fc = 0.40 +/- 0.03 Hz, n = 6). Single-Cl- channels showed complex gating kinetics with long lasting (seconds) openings interrupted by similar long closures. In the open state, channels exhibited fast burst-like closures. Since the patches normally contained more than a single channel, it was not possible to measure open and closed dwell-time distributions for comparing single-Cl- channel activity with the kinetic features of whole-cell currents. However, the power density spectrum of Cl- currents of cell-attached and excised outside-out patches contained both high and low frequency Lorentzian components, with the corner frequency of the slow component (fc = 0.40 +/- 0.02 Hz, n = 4) similar to that of whole-cell current fluctuations. Chloride channels exhibited multiple conductance states with similar Goldman-Hodgkin-Katz-type rectification. Single-channel permeabilities covered the range from approximately 0.6.10(-14) cm5/s to approximately 6.10(-14) cm3/s, corresponding to a limiting conductance (gamma 150/150) of approximately 3.5 pS and approximately 35 pS, respectively. All states reversed near the same membrane potential, and they exhibited similar halide ion selectivity, P1 > PCl approximately PBr. Accordingly, Cl- current amplitudes larger than current flow through the smallest channel unit resolved seem to result from simultaneous open/shut events of two or more channel units.     

Genetic relatedness of the genomes of equine herpesvirus types 1, 2, and 3.

Genomic DNAs of equine herpesvirus type 1 (EHV-1), EHV-2 (equine cytomegalovirus), and EHV-3 were examined by reassociation kinetic and thermal denaturation analyses to determine the extent and degree of homology among the three viral DNAs. Results of reassociation analyses indicated a limited homology among the three EHV genomes. Homologous DNA sequences equivalent to 1.8 to 3.7 megadaltons between EHV-1 and equine cytomegalovirus, 7.6 to 8.2 megadaltons between EHV-1 and EHV-3, and 1.3 to 1.9 megadaltons between equine cytomegalovirus and EHV-3 were detected. Examination by thermal denaturation of the DNA homoduplexes and heteroduplexes formed during reassociation revealed a high degree of base pairing within the duplexes, suggesting that closely related sequences may be conserved among the genomes of EHV.     

In vivo and in vitro processing of seed reserve protein in the endoplasmic reticulum: evidence for two glycosylation steps

Cotyledons of the common bean (Phaseolus vulgaris L.) synthesize large amounts of the reserve protein phaseolin. The polypeptides are synthesized on membrane-bound polysomes, pass through the endoplasmic reticulum (ER) and accumulate in protein bodies. For a study of the biosynthesis and processing of phaseolin, developing cotyledons were labeled with radioactive amino acids, glucosamine and mannose, and isolated fractions (polysomal RNA, polysomes, and rough ER) were used for in vitro protein synthesis. Newly synthesized phaseolin present in the ER of developing cotyledons can be fractioned into four glycopolypeptides by SDS PAGE. In vitro synthesis with polysomal RNA results in the formation of two polypeptides by polysome run-off shows that glycosylation is a co-translational event. The two unglycosylated polypeptides formed by polysome run-off are slightly smaller than the two polypeptides formed by in vitro translation of isolated RNA, indicating that a signal peptide may be present on these polypeptides. Run-off synthesis with rough ER produces a pattern of four polypeptides similar to the one obtained by in vivo labeling. The two abundant glycopolypeptides formed by polysome run-off. This result indicates the existence of a second glycosylation event for the abundant polypeptides. Inhibition of glycosylation by Triton X-100 during chain-completion with rough ER was used to show that these two glycosylation steps normally occur sequentially. Both glycosylation steps are inhibited by tunicamycin. Analysis of carhohydrate to protein ratios of the different polypeptides and of trypsin digests of polypeptides labeled with [(3)H]glucosamine confirmed the conclusion that some glycosylated polypeptides contain two oligosaccharide chains, while others contain only one. An analysis of tryptic peptide maps shows that each of the unglycosylated polypeptides is the precursor for one glycosylated polypeptide with one oligosaccharide chain and one with two oligosaccharide chains.