Mitochondrial DNA-based analysis of genetic variation and relatedness among Sri Lankan indigenous chickens and the Ceylon junglefowl (Gallus lafayetti)

Indigenous chickens (IC) in developing countries provide a useful resource to detect novel genes in mitochondrial and nuclear genomes. Here, we investigated the level of genetic diversity in IC from five distinct regions of Sri Lanka using a PCR-based resequencing method. In addition, we investigated the relatedness of IC to different species of junglefowls including Ceylon (CJF; Gallus lafayetti), a subspecies that is endemic to Sri Lanka, green (Gallus varius), grey (Gallus sonneratii) and red (Gallus gallus) junglefowls. A total of 140 birds including eight CJF were used to screen the control region of the mitochondrial DNA sequence for single nucleotide polymorphisms (SNPs) and other variants. We detected and validated 44 SNPs, which formed 42 haplotypes and six haplogroups in IC. The SNPs observed in the CJF were distinct and the D-loop appeared to be missing a 62-bp segment found in IC and the red junglefowl. Among the six haplogroups of IC, only one was region-specific. Estimates of haplotype and nucleotide diversities ranged from 0.901 to 0.965 and from 0.011 to 0.013 respectively, and genetic divergence was generally low. Further, variation among individuals within regions accounted for 92% of the total molecular variation among birds. The Sri Lankan IC were more closely related to red and grey junglefowls than to CJF, indicating multiple origins. The molecular information on genetic diversity revealed in our study may be useful in developing genetic improvement and conservation strategies to better utilize indigenous Sri Lankan chicken resources.

A novel mouse model of human breast cancer stem-like cells with high CD44+CD24-/lower phenotype metastasis to human bone

Abstract #4155

Background: At present, our understanding of the development of bone metastasis is limited. Therefore, little progress has been made in preventing skeletal metastasis in the breast cancer patient. A satisfactory animal model that avoids the species-specific factor and simultaneously shares similarities to the clinical pathophysiological progression of breast cancer metastasizing to bone is unavailable. A subpopulation (CD44+/CD24-/lower) of breast cancer cells possesses stem/progenitor cell properties (cancer stem-like cell). CD44 potentiates the adherence of metastatic breast cancer cells to bone marrow endothelial cells. In the present study, we used hepatocyte growth factor to enhance the proportion of CD44+/CD24-/lower subpopulation in the human breast cancer cell line MDA-MB-231. We used these human breast cancer stem-like cells and implantation of human bone to build a novel human-source model of human breast cancer skeletal metastasis.
 Methods: The human breast cancer cell line MDA-MB-231 was cultured in serum-free DMEM-F12 supplemented with growth factors. Cells in different subpopulations were separated by Percoll gradient centrifugation and incubated in the presence of 50 ng/mL hepatocyte growth factor. The proportion of CD44+/CD24-/lower subpopulation in the human breast cancer cell line MDA-MB-231 was detected with flow cytometry. Before injection with human breast cancer stem-like cells, the experimental animals were implanted with human bone in the right or left dorsal flanks. Animals in Groups A, B, and C were injected with 1 X 105, 1 X 106 human breast cancer stem-like cells, and 1 X 106 parental MDA-MB-231 cells, respectively. A positive control group (D) without implantation of human bone (non-human source model) was also injected with 1 X 106 MDA-MB-231 cells. A group of negative controls (E) with human bone implantation was injected with isotonic sodium chloride. For each group, Micro-SPECT was performed at weeks 4 and 7, and all animals were sacrificed at week 8. Immunohistochemistry was performed for CD34, CD105, SMA, CD44, CD24, CK, CXCR4, and OPN. mRNA levels of CD44, CD24, CXCR4, and OPN in bone metastasis tissues were analyzed by real-time quantitative polymerase chain reaction.
 Results: New vessels and connective tissue were found on the surface of implanted human bones and cells stained positive for antibodies against human CD105, SMA, and CD34, indicating that implanted human bones were viable and functional. Histologic and immunohistochemical analysis confirmed the metastases as cancer cells. Importantly, the results demonstrated that cells in implanted human bones of group B, which received 1 X 106 cancer stem-like cells, stained strongly positive for CD44, CXCR4, and OPN, whereas that of other groups showed no or minimum staining. Moreover, group B had the highest incidence of human bone metastasis (77.8%, P = 0.0230) and no accompaniment of other tissue metastasis. The real-time polymerase chain reaction (PCR) showed an increase of CD44 mRNA in metastatic bone tissues in group B compared with that of groups C and D (15.2- and 21.1-fold, respectively). The mRNA levels of CXCR4 and OPN (8.4- and 28.4-fold, respectively) in bone metastasis tissues of group B were all higher than that of groups C and D (4.8- and 11.6-fold; respectively). The levels of CD24 mRNA in group B were lowest, measuring only 30 percent of that in groups C and D.
 Conclusion: This study indicates that in the novel human source model of breast cancer, breast cancer stem-like cells demonstrate a higher human bone-seeking ability, which may contribute to increase metastasis incidence and attenuate species-specific influences. Its mechanism might be related to the higher expressions of CD44, CXCR4 and OPN, and the lower expression of CD24 in breast cancer stem-like cells. The model shares more similarities with clinical pathological features of bone metastatic patients. It will be helpful for further study of the mechanisms and subclinical diagnosis of bone metastasis.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4155.

Electroluminescent devices based on amorphous SiN/Si quantum dots/amorphous SiN sandwiched structures

A single layer of dense Si quantum dots with average size of 4 nm sandwiched in amorphous SiN layers was prepared by laser crystallization of ultrathin amorphous Si film followed by subsequently thermal annealing. The electroluminescent diodes were fabricated by evaporating Al electrodes on back sides of p-Si substrates and the top surface of samples. Room temperature electroluminescence can be detected with applying the negative voltage around 10V on the top gate electrode and the luminescent intensity is increased with increasing the applied voltage. It was found that the integrated luminescent intensity is linearly proportional to the injection current which suggested the intensity depends on the concentrations of injected carriers after Fowler-Nordheim tunneling through amorphous SiN barriers. The influence of the amorphous SiN with different band gap on the device performance was also discussed briefly.

220 SYNERGISTIC EFFECT ON EMBRYO DEVELOPMENT BY INCLUSION OF SUPPLEMENTAL EMBRYOS IN AGAR CHIPS

The main scope of this study was to evaluate the likelihood of a helper effect of agar-embedded cleaved embryos on a low number of free embryos at a similar stage of development within the same culture droplet. Such an improved system could be beneficial within ovum pickup/in vitro embryo production (OPU/IVEP) combined protocols whenever a low number of OPU-derived cleaved embryos are produced per donor. Oocytes were recovered from abattoir ovaries, and after in vitro maturation (IVM) and in vitro fertilization (IVF), presumptive zygotes were deprived of cumulus investment and allocated into culture droplets for 24 h. At 48 h from IVF, 4- to 8-cell cleaved embryos were randomly allocated into a control and a treatment group. Control groups consisted of 1, 3, 5, and 10 embryos, respectively, in 50-μL droplets. Treatment groups consisted of 1, 3, and 5 free embryos with the addition of 9, 7, and 5 embryos, respectively, at a similar stage of development embedded in agar chips, so as to reach a total number of 10 cleaved embryos in each culture droplet. Culture was performed for both the control and treatment groups in SOF medium droplets covered with mineral oil, with the supplementation of essential and nonessential amino acids in a controlled gas atmosphere consisting of 5% CO2, 7% O2, and 88% N2 at 39°C. Final embryo output was checked at Day 7 from IVF. When considering only free embryos, the difference in progression to blastocyst development was highly significant between the control and treatment groups: 1) group 1 v. 1 + 9: 6.6 v. 84.3% (P = 0.00000); 2) group 3 v. 3 + 7: 11.1 v. 41.3% (P = 0.00001); 3) group 5 v. 5 + 5: 24.4 v. 42.2% (P = 0.00001). Rate of blastocyst development in the control group containing 10 cleaved embryos was not significantly different from free cleaved embryos in the 3 + 7 (39.2 v. 41.3%, P = 0.71) and 5 + 5 treatment groups (39.2 v. 42.2%, P = 0.54), but was significantly lower when compared with the 1 + 9 treatment group (39.2 v. 84.3%, P = 0.000). For 1, 3, 5, and 10 control group embryos, the numbers of replicates and total cleaved embryos used (n) were 30 (n = 30), 27, (n = 81), 27 (n = 135), and 39 (n = 390), respectively. For the 1 + 9, 3 + 7, and 5 + 5 treatment group embryos, the numbers of replicates and total cleaved embryos used were 32 (n = 32), 29 (n = 87), and 27 (n = 135), respectively. In conclusion, a beneficial effect of agar-embedded embryos on the development of free embryos within the same culture droplet was shown. A striking improvement in late-stage embryo development was particularly evident when considering the 1 v. 1 + 9 control and treatment groups. These results may foster a different strategic approach in in vitro culture to enhance embryo development from highly valuable donors.

203 EFFECT OF FRUCTOSE ON THE DEVELOPMENT OF BOVINE SEXED EMBRYOS IN VITRO

It is important to optimize the condition of culture to promote the development of embryos fertilized by sex-sorted sperm. Fructose is a monosaccharide hexose that can be used as a substrate for glycolysis. Recently, there has been interest in exploring the embryotrophic properties of fructose during bovine embryo culture. The present study was undertaken to ascertain the effect of supplementation of fructose in culture on the development of sexed embryos in vitro. A total of 2310 slaughterhouse dairy oocytes, spread over 3 experimental replicates, were subjected to routine in vitro maturation (IVM) for 22 h. The maturation medium was M-199 with Earl’s salts, L-glutamine, 26.19 mm sodium bicarbonate, and 25 mm HEPES plus 10% fetal bovine serum. Fertilization of IVM oocytes was performed in Brackett and Oliphant’s medium by using frozen and sorted X-sperm from a single bull. Groups of 50 matured oocytes were added to a final volume of 100 μL of fertilization medium, with a final concentration of 0.3 × 106 spermatozoa mL–1. The oocytes were incubated with X-sperm for 6 h in 5% CO2 humidified air at 39°C. Presumptive zygotes were randomly allocated to culture either in a control medium (6 mg mL–1 of BSA CR1aa medium) or with 4.5 mm fructose added to CR1aa culture medium for 7 days in an atmosphere of 5% O2, 5% CO2, and 90% N2 at 39°C. Embryo cleavage, and development to the morulae and blastocyst stages were evaluated on Days 2, 5, and 7 of culture, respectively. Embryos were graded according to International Embryo Transfer Society standards. The total number of blastocysts recorded was the sum of grade C1 and C2 embryos. Data were analyzed by using the General Linear Model (SPSS 11.0, SPSS Inc., Chicago, IL, USA). As shown in Table 1, addition of fructose to the culture medium affected neither the rate of cleavage nor subsequent development to the morula stage or total blastocyst development. However, the proportion of C1-grade embryos of the total blastocysts was significantly (P < 0.05) improved. This study suggests that addition of fructose to the culture medium can promote embryo quality and yields that are suitable for embryo transfer. Table 1.Effect of addition of fructose on in vitro development of bovine sexed embryos

Preparation of activated carbons from wet activated sludge by direct chemical activation

An improved method for preparing activated carbons from wet waste activated sludge (WAS) by direct chemical activation was studied in this paper. The effects of processing parameters on iodine adsorption capacity of the product were investigated. Results show that sludge-based activated carbon prepared with KOH had a larger iodine value than those activated with ZnCl(2) and KCl. The maximum iodine value was observed at the KOH concentration of 0.50 M. Increasing the impregnation time from 10 to 20 h resulted in a 20% increase in the iodine value. The highest iodine value was obtained at the activation temperature of 600 degrees C and holding time of 1 h. Sludge water content had insignificant effects on the iodine value of products. Raw WAS with a water content of 93.2% can be converted into an activated carbon with a high specific surface area of 737.6 m(2) g(-1) and iodine value of 864.8 mgg(-1) under optimum experimental conditions. Other physical properties such as total pore volume, micropore volume and mean pore diameter of the product were also reported and compared with those of commercial activated carbon.

Disability in optic neuritis correlates with diffusion tensor-derived directional diffusivities

OBJECTIVE

To determine the potential of directional diffusivities from diffusion tensor imaging (DTI) to predict clinical outcome of optic neuritis (ON), and correlate with vision, optical coherence tomography (OCT), and visual evoked potentials (VEP).

METHODS

Twelve cases of acute and isolated ON were imaged within 30 days of onset and followed prospectively. Twenty-eight subjects with a remote clinical history of ON were studied cross-sectionally. Twelve healthy controls were imaged for comparison. DTI data were acquired at 3T with a surface coil and 1.3 x 1.3 x 1.3 mm(3) isotropic voxels.

RESULTS

Normal DTI parameters (mean +/- SD, microm(2)/ms) were axial diffusivity = 1.66 +/- 0.18, radial diffusivity = 0.81 +/- 0.26, apparent diffusion coefficient (ADC) = 1.09 +/- 0.21, and fractional anisotropy (FA) = 0.43 +/- 0.15. Axial diffusivity decreased up to 2.5 SD in acute ON. The decrease in axial diffusivity at onset correlated with visual contrast sensitivity 1 month (r = 0.59) and 3 months later (r = 0.65). In three subjects followed from the acute through the remote stage, radial diffusivity subsequently increased to > 2.5 SD above normal, as did axial diffusivity and ADC. In remote ON, radial diffusivity correlated with OCT (r = 0.81), contrast sensitivity (r = 0.68), visual acuity (r = 0.56), and VEP (r = 0.54).

CONCLUSION

In acute and isolated demyelination, axial diffusivity merits further investigation as a predictor of future clinical outcome. Diffusion parameters are dynamic in acute and isolated optic neuritis, with an initial acute decrease in axial diffusivity. In remote disease, radial diffusivity correlates with functional, structural, and physiologic tests of vision.

Increased expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in rat cardiac allografts

This study was designed to investigate the role of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) during chronic cardiac allograft rejection. Wistar rats were used as donors, and SD rats as recipients heterotopic cardiac transplants. Recipients pretreated with inoculation of donor splenocytes (SPC) followed by cyclophosphamide (CP) were divided into 4 groups: (A) untreated group (n = 18) without immunosuppression; (B) SPC plus CP-treated group (n = 18) that were euthanized at 15-120 days posttransplantation; (C) CsA-treated group (n = 18) euthanized at 2-3 months posttransplantation; and (D) tolerance group (n = 18) treated with SPC plus CP and monitored for at least 1 year posttransplantation. Cardiac allografts were harvested at various times for immunohistochemical studies performed to evaluate the expression of ICAM-1 and VCAM-1. Pretreatment of animals with SPC and CP induced long-term cardiac allograft survival. Immunohistochemical staining demonstrated a low level of ICAM-1 and VCAM-1 expression in cardiac allograft muscle and coronary arteries among Groups B and D. In contrast, the expressions of ICAM-1 and VCAM-1 in cardiac allografts of Groups A and C were significantly higher than those in Groups B and D. Our results suggested that the expression of ICAM-1 and VCAM-1 plays an important role during the development of chronic cardiac allograft rejection.

Pioneer factors, genetic competence, and inductive signaling: programming liver and pancreas progenitors from the endoderm

The endoderm is a multipotent progenitor cell population in the embryo that gives rise to the liver, pancreas, and other cell types and provides paradigms for understanding cell-type specification. Studies of isolated embryo tissue cells and genetic approaches in vivo have defined fibroblast growth factor/mitogen-activated protein kinase (FGF/MAPK) and bone morphogenetic protein (BMP) signaling pathways that induce liver and pancreatic fates in the endoderm. In undifferentiated endoderm cells, the FoxA and GATA transcription factors are among the first to engage silent genes, helping to endow competence for cell-type specification. FoxA proteins can bind their target sites in highly compacted chromatin and open up the local region for other factors to bind; hence, they have been termed "pioneer factors." We recently found that FoxA proteins remain bound to chromatin in mitosis, as an epigenetic mark. In embryonic stem cells, which lack FoxA, FoxA target sites can be occupied by FoxD3, which in turn helps to maintain a local demethylation of chromatin. By these means, a cascade of Fox factors helps to endow progenitor cells with the competence to activate genes in response to tissue-inductive signals. Understanding such epigenetic mechanisms for transcriptional competence coupled with knowledge of the relevant signals for cell-type specification should greatly facilitate efforts to predictably differentiate stem cells to liver and pancreatic fates.

The experimental study of cardiac allograft vasculopathy and myocardial fibrosis in rats

We sought to analyze the development of myocardial fibrosis and cardiac allograft vasculopathy (CAV) as a theoretical basis for the prevention and treatment of rejection. Heterotopic cardiac transplantation was performed from Wistar rats to Sprague-Dawley rats. The recipients pretreated with donor splenocyte (SPC) infusion followed by cyclophosphamide (CP) were divided into 3 groups: Control animals without immunosuppression (Group 1; n = 10); Group 2, CsA treatment (n = 10) with euthanasia 2-3 months posttransplantation; and Group 3 (n = 20), CP plus SPC treatment with 10 recipients euthanized at 2 weeks posttransplantation and 10 animals monitored for at least 1 year posttransplantation. Histological studies were performed to evaluate myocardial fibrosis and CAV; 2-3 days after transplantation, there was abundant infiltration of collagenous fibers in the adventitia and intima of the coronary arteries in Group 1 allografts. Group 2 allografts demonstrated abundant infiltration of collagenous fibers in the adventitia and intima of arteries and arterioles resulting in significant luminal stenosis. In contrast, pretreatment of animals with SPC and CP induced long-term allograft survival; myocardial fibrosis and CAV were dramatically reduced in Group 3 compared with Groups 1 and 2. The infiltration of collagenous fibers in coronary arteries was one of the major causes of CAV. Preconditioning of recipients with SPC followed by CP not only induced immune tolerance but also alleviated myocardial fibrosis and CAV in allografts.

Human olfactory epithelial cells generated in vitro express diverse neuronal characteristics

The olfactory epithelium constitutes the sole source of regenerating neural cells that can be obtained from a living human. As such, primary cultures derived from human olfactory epithelial biopsies can be utilized to study neurobiological characteristics of individuals under different conditions and disease states. Here, using such human cultures, we report in vitro generation of cells that exhibit a complex neuronal phenotype, encompassing receptors and signaling pathways pertinent to both olfaction and other aspects of CNS function. Using in situ hybridization, we demonstrate for the first time the native expression of olfactory receptors in cultured cells derived from human olfactory epithelial tissue. We further establish the presence and function of olfactory transduction molecules in these cells using immunocytochemistry, calcium imaging and molecular methods. Western blot analysis revealed the expression of neurotransmitter receptors for dopamine (D2R), 5-HT (5HT2C) and NMDA subtypes 1 and 2A/2B. Stimulation with dopamine or 5-HT enhanced receptor G protein activation in a subtype specific manner, based on 35S-guanosine triphosphate incorporation assay. Functional characteristics of the cultured cells are demonstrated through enhanced tyrosine phosphorylation of NMDAR 2A/2B and recruitment of signaling partners in response to NMDA stimulation. The array of neuronal characteristics observed here establishes that proliferating cells derived from the human olfactory epithelium differentiate in vitro to express functional and molecular attributes of mature olfactory neurons. These cultured neural cells exhibit neurotransmitter pathways important in a number of neuropsychiatric disorders. Their ready availability from living humans thus provides a new tool to link functional and molecular features of neural cells with clinical characteristics of individual living patients.

Oncolytic adenovirus retargeted to Delta-EGFR induces selective antiglioma activity

The fact that glioblastomas, which are one of the most devastating cancers, frequently express the Delta-EGFR (epithelial growth factor receptor) also called mutant variant III of EGFR (EGFRvIII) suggests that this cancer cell-specific receptor might serve as an ideal target for cancer therapy. To assess its potential as such a target, we constructed an oncolytic adenovirus with Retargeted Infectivity Via EGFR (Delta-24-RIVER) on the backbone of Delta-24. This new oncolytic adenovirus targets, as Delta-24 does, the disrupted Rb pathway in cancer cells; in addition, this adenovirus has also been retargeted through the abrogation of CAR binding (Y477A mutation in adenoviral fiber protein) and insertion of an EGFRvIII-specific binding peptide in the HI loop of the fiber protein. As compared with Delta-24, Delta-24-RIVER induced EGFRvIII-selective cytotoxicity in U-87 MG isogenic cell lines and in tetracycline-inducible EGFRVIII expressing U-251 MG cells. Accordingly, by tittering the viral progeny and examining fiber protein expression in the above cells, we showed that the replication of this new construct also correlated with EGFRvIII expression. Consistently, immunohistochemistry staining of the adenoviral capsid protein hexon in the virus-treated tumors revealed that the virus replicated more efficiently in EGFRvIII-expressing U-87 MG.DeltaEGFR xenografts than in the tumors grown from U-87 MG cells. Importantly, treatment with Delta-24-RIVER prolonged the survival of animals with intracranial xenografts derived from U-87 MG.DeltaEGFR cells. Therefore, our results constitute the first proof of the direct targeting of a cancer-specific receptor using an oncolytic adenovirus.

Coupling between neuronal nitric oxide synthase and glutamate receptor 6-mediated c-Jun N-terminal kinase signaling pathway via S-nitrosylation contributes to ischemia neuronal death

S-nitrosylation, as a post-translational protein modification, recently has been paid more and more attention in stroke research. S-nitrosylation regulates protein function by the mechanisms of covalent attachment that control the addition or the removal of nitric oxide (NO) from a cysteine thiol. The derivation of NO is established by the demonstration that, in cerebral neurons, NO mainly generates from neuronal nitric oxide synthase (nNOS) during the early stages of reperfusion. In the past researches, we demonstrate that global ischemia-reperfusion facilitates the activation of glutamate receptor 6 (GluR6) -mediated c-Jun N-terminal kinase (JNK) signaling pathway. The objective of this study is primarily to determine, during the early stages of reperfusion in rat four-vessel occlusion (4-VO) ischemic model, whether nNOS-derived NO affects the GluR6-mediated JNK signaling route via S-nitrosylation which is performed mainly by the biotin switch assay. Here, we show that administration of 7-nitroindazole, an inhibitor of nNOS, or ketamine, an antagonist of N-methyl-d-aspartate receptor (NMDAR), diminishes the increased S-nitrosylation of GluR6 induced by cerebral ischemia-reperfusion. In contrast, 2-amion-5,6-dihydro-6-methyl-4H-1,3-thiazine, an inhibitor of inducible NO synthase does not affect S-nitrosylation of GluR6. Moreover, treatment with sodium nitroprusside (SNP), an exogenous NO donor, increases the S-nitrosylation and phosphorylation of nNOS, leading to the attenuation of the increased S-nitrosylation of GluR6 and the assembling of GluR6* postsynaptic density protein 95 (PSD95)* mixed lineage kinase 3 (MLK3) signaling module induced by cerebral ischemia-reperfusion. The results also show that GluR6 downstream MLK3* mitogen activated protein kinase kinase 4/7* JNK signaling module and nuclear or non-nuclear apoptosis pathways are involved in the above signaling route. However, dithiothreitol (DTT) antagonizes the neuroprotection of SNP. Treatment with DTT alone, as a negative control, prevents S-nitrosylation of proteins, which indicates the existence of endogenously produced S-nitrosylation. These data suggest that GluR6 is S-nitrosylated by endogenous NO in cerebral ischemia-reperfusion, which is possibly correlated with NMDAR* PSD95* nNOS signaling module, and further activates GluR6* PSD95* MLK3 signaling module and JNK signaling pathway. In contrast, exogenous NO donor antagonizes the above action of endogenous NO generated from nNOS. Thus, our results provide the coupling of nNOS with GluR6 by S-nitrosylation during the early stages of ischemia-reperfusion, which can be a new approach for stroke therapy.

Biomechanical effects of autonomous augmentation on the adjacent unaugmented vertebral bodies: influence of the number of functional spinal units in a finite element model

PURPOSE

The results of finite element analysis (FEA) studies on the effect of augmentation of one vertebral body (VB), using vertebroplasty (VP) or balloon kyphoplasty (BKP), on the biomechanics of the adjacent and nonadjacent VBs are contradictory. One reason for this record is that different levels of the spine, numbers of structures, and numbers of functional spinal units (FSUs) (X) were included in the models used in different studies. The purpose of the present study was to clarify this effect as far as X is concerned.

METHODS

A validated three-dimensional solid model of the lumbar spine was constructed from computed tomography scans and prophylactic augmentation of L2 was simulated. In the FEA, the model was subjected to a uniformly distributed compressive load (total load = 1300 N) on the superior endplate of L1. The extent to which a change in X affects the values of the mean von Mises stress (sigmaVM) and the mean elastic strain energy density (ESED) in all structures adjacent to L2 was determined. (These changes were with respect to the case where all the VBs in the model are intact.)

RESULTS

As X increased (from 1 to 2, from 2 to 3, and from 3 to 4), there were clear variations in the number of stable changes in both sigmaVM and ESED in each structure. The largest number of these changes occurred when X changed from 2 to 3.

CONCLUSION

The results suggest that three is the number of FSUs that should be included in models of the lumbar spine to be used in FEA studies of VP and BKP.