Vertebrae In Pigs Research Articles

Characterization of Pig Vertebrae under Axial Compression Integrating Radiomic Techniques and Finite Element Analysis

The study of pig bones, due to their similarity with human tissues, has facilitated the development of technological tools that help in the diagnosis of diseases and injuries affecting the skeletal system. Radiomic techniques involving medical image segmentation, along with finite element analysis, enable the detailed study of bone damage, loss of density, and mechanical functionality, which is a significant advancement in personalized medicine. This study involves conducting experimental tests on L3–L6 pig vertebrae under axial loading conditions. The mechanical properties of these vertebrae are analyzed, and the maximum loads they can sustain within the elastic range are determined. Additionally, three-dimensional models are generated by segmenting computerized axial tomography (CAT) scans of the vertebrae. Digital shadows of the vertebrae are constructed by assigning an anisotropic material model to the segmented geometries. Then, finite element analysis is performed to evaluate the elastic characteristics, stress, and displacement. The findings from the experimental data are then compared to the numerical model, revealing a strong correlation with differences of less than 0.8% in elastic modulus and 1.53% in displacement. The proposed methodology offers valuable support in achieving more accurate medical outcomes, employing models that serve as a diagnostic reference. Moreover, accurate bone modeling using finite element analysis provides valuable information to understand how implants interact with the surrounding bone tissue. This information is useful in guiding the design and optimization of implants, enabling the creation of safer, more durable, and biocompatible medical devices that promote optimal osseointegration and healing in the patient.

A Novel Point Set Registration-Based Hand-Eye Calibration Method for Robot-Assisted Surgery.

Pedicle screw insertion with robot assistance dramatically improves surgical accuracy and safety when compared with manual implantation. In developing such a system, hand-eye calibration is an essential component that aims to determine the transformation between a position tracking and robot-arm systems. In this paper, we propose an effective hand-eye calibration method, namely registration-based hand-eye calibration (RHC), which estimates the calibration transformation via point set registration without the need to solve the AX=XB equation. Our hand-eye calibration method consists of tool-tip pivot calibrations in two-coordinate systems, in addition to paired-point matching, where the point pairs are generated via the steady movement of the robot arm in space. After calibration, our system allows for robot-assisted, image-guided pedicle screw insertion. Comprehensive experiments are conducted to verify the efficacy of the proposed hand-eye calibration method. A mean distance deviation of 0.70 mm and a mean angular deviation of 0.68° are achieved by our system when the proposed hand-eye calibration method is used. Further experiments on drilling trajectories are conducted on plastic vertebrae as well as pig vertebrae. A mean distance deviation of 1.01 mm and a mean angular deviation of 1.11° are observed when the drilled trajectories are compared with the planned trajectories on the pig vertebrae.

A genome-wide association study for the number of teats in European rabbits (Oryctolagus cuniculus) identifies several candidate genes affecting this trait.

In the European rabbit (Oryctolagus cuniculus), a polytocous livestock species, the number of teats indirectly impacts the doe reproduction efficiency and, in turn, the sustainable production of rabbit meat. In this study, we carried out a genome-wide association study (GWAS) for the total number of teats in 247 Italian White does included in the Italian White rabbit breed selection program, by applying a selective genotyping approach. Does had either 8 (n=121) or 10 teats (n=126). All rabbits were genotyped with the Affymetrix Axiom OrcunSNP Array. Genomic data from the two extreme groups of rabbits were also analysed with the single-marker fixation index statistic and combined with the GWAS results. The GWAS identified 50 significant SNPs and the fixation index analysis identified a total of 20 SNPs that trespassed the 99.98th percentile threshold, 19 of which confirmed the GWAS results. The most significant SNP (P=4.31×10-11 ) was located on OCU1, close to the NUDT2 gene, a breast carcinoma cells proliferation promoter. Another significant SNP identified as candidate gene NR6A1, which is well known to play an important role in affecting the correlated number of vertebrae in pigs. Other significant markers were close to candidate genes involved in determining body length in mice. Markers associated with increased number of teats could be included in selection programmes to speed up the improvement for this trait in rabbit lines that need to increase maternal performances.

Abstract No. 492 Adjacent metallic instrumentation does not limit bone ablation when using a bipolar radiofrequency device

An unproven theory that has favored radiotherapy and limited wider application of first-line ablation for patients with painful metastatic bone tumors is the belief that adjacent metallic instrumentation impairs outcomes for local tumor control by serving as a heat sink. This theory has not been tested with modern bipolar radiofrequency (RFA) systems FDA cleared and specifically calibrated for bone ablation. The current study challenges a commercially available bipolar RFA device maximally, with a screw interrupting the center of the return circuit, to determine effects on ablation zone size and temperature, as well as assess whether titanium versus stainless steel instrumentation has different effects, and whether the instrumentation heats sufficiently to create nontarget ablation. Ex vivo ablations were performed using freshly harvested pig vertebrae. Image-guided RFA probe placement and screw placement allowed preparation of 15 vertebrae for ablations, 5 with no screw (control), 5 with adjacent orthogonal titanium screw, and 5 with adjacent orthogonal stainless steel screw. 3 Watt RFA was performed for 5 minutes or until impedance stopped the ablation automatically. Real-time temperature measurements were obtained from the built-in thermocouple in the RFA device and an additional thermocouple on the adjacent screw when applicable. Vertebrae were ananlyzed with 3-Tesla MRI, gross sectioning and histopathology. At 5 minutes, ablation zone temperatures increased mean 21.5 ± 2.1, 20 ± 2.9, 17.2 ± 3.5°C (control, titanium, steel respectively, P = 0.3, one-way ANOVA; P = 0.09, linear regression). At 5 minutes, screw temperatures increased mean 0.3 ± 1°C (titanium, P = 0.6, paired t-test), 4.6 ± 2.9°C (steel, P = 0.023, paired t-test). MRI, gross, histopathology confirmed ablation contained and extended beyond any screws. Adjacent metallic instrumentation did not significantly limit ablation in this experiment using a bipolar RFA device. The stainless steel screw demonstrated statistically significant heating by approximately 5 degrees Celsius at 5 minutes of a low power (3 Watt) RF cycle. These findings support further in vivo study to assess the short-term biologic response and remodeling with juxta-metallic bone RFA.

A QTL for Number of Teats Shows Breed Specific Effects on Number of Vertebrae in Pigs: Bridging the Gap Between Molecular and Quantitative Genetics.

Modern breeding schemes for livestock species accumulate a large amount of genotype and phenotype data which can be used for genome-wide association studies (GWAS). Many chromosomal regions harboring effects on quantitative traits have been reported from these studies, but the underlying causative mutations remain mostly undetected. In this study, we combine large genotype and phenotype data available from a commercial pig breeding scheme for three different breeds (Duroc, Landrace, and Large White) to pinpoint functional variation for a region on porcine chromosome 7 affecting number of teats (NTE). Our results show that refining trait definition by counting number of vertebrae (NVE) and ribs (RIB) helps to reduce noise from other genetic variation and increases heritability from 0.28 up to 0.62 NVE and 0.78 RIB in Duroc. However, in Landrace, the effect of the same QTL on NTE mainly affects NVE and not RIB, which is reflected in reduced heritability for RIB (0.24) compared to NVE (0.59). Further, differences in allele frequencies and accuracy of rib counting influence genetic parameters. Correction for the top SNP does not detect any other QTL effect on NTE, NVE, or RIB in Landrace or Duroc. At the molecular level, haplotypes derived from 660K SNP data detects a core haplotype of seven SNPs in Duroc. Sequence analysis of 16 Duroc animals shows that two functional mutations of the Vertnin (VRTN) gene known to increase number of thoracic vertebrae (ribs) reside on this haplotype. In Landrace, the linkage disequilibrium (LD) extends over a region of more than 3 Mb also containing both VRTN mutations. Here, other modifying loci are expected to cause the breed-specific effect. Additional variants found on the wildtype haplotype surrounding the VRTN region in all sequenced Landrace animals point toward breed specific differences which are expected to be present also across the whole genome. This Landrace specific haplotype contains two missense mutations in the ABCD4 gene, one of which is expected to have a negative effect on the protein function. Together, the integration of largescale genotype, phenotype and sequence data shows exemplarily how population parameters are influenced by underlying variation at the molecular level.

Estimating the Temperature of Heat-exposed Bone via Machine Learning Analysis of SCI Color Values: A Pilot Study.

Determining maximum heating temperatures of burnt bones is a long-standing problem in forensic science and archaeology. In this pilot study, controlled experiments were used to heat 14 fleshed and defleshed pig vertebrae (wet bones) and archaeological human vertebrae (dry bones) to temperatures of 400, 600, 800, and 1000°C. Specular component included (SCI) color values were recorded from the bone surfaces with a Konica-Minolta cm-2600d spectrophotometer. These color values were regressed onto heating temperature, using both a traditional linear model and the k-nearest neighbor (k-NN) machine-learning algorithm. Mean absolute errors (MAE) were computed for 1000 rounds of temperature prediction. With the k-NN approach, the median MAE prediction errors were 41.6°C for the entire sample, and 20.9°C for the subsample of wet bones. These results indicate that spectrophotometric color measurements combined with machine learning methods can be a viable tool for estimating bone heating temperature.

Monitoring reduced scattering coefficient in pedicle screw insertion trajectory using near-infrared spectroscopy.

Pedicle screw (PS) implantation is an ideal treatment for severe multilevel vertebra instabilities. The accuracy of fixating PS is a key factor of spinal surgery. We developed a near-infrared spectroscopy device with a needlelike optical fiber probe to monitor optical parameters (reduced scattering coefficient) of vertebra models in real time. The fresh-frozen cadaver, cats and porcine vertebras were first studied in the experiments. Moreover, the reduced scattering coefficient (μ' s) along the different trajectories of PS insertion was obtained. In the fresh-frozen cadavera experiment, μ' s values could be used to distinguish the different compositions of the thoracic vertebra. In cat vertebra experiment, μ' s values of vertebrae bones, including cortical bone (15.30±0.18cm(-1)), cancellous bone (7.84±1.11cm(-1)) and spinal cord (19.46±0.21cm(-1)), were different in vivo. In the pig vertebrae experiment, there were obvious differences between the normal and abnormal PS puncture curves based on μ' s values. Thus, μ' s values measured by using the proposed device could be used as the pattern factor in spinal fusion surgery. Our studies demonstrate that near-infrared spectroscopy method may be potentially used for assisting the PS insertion.

A study of vertebra number in pigs confirms the association of vertnin and reveals additional QTL.

BackgroundFormation of the vertebral column is a critical developmental stage in mammals. The strict control of this process has resulted in little variation in number of vertebrae across mammalian species and no variation within most mammalian species. The pig is quite unique as considerable variation exists in number of thoracic vertebrae as well as number of lumbar vertebrae. At least two genes have been identified that affect number of vertebrae in pigs yet considerable genetic variation still exists. Therefore, a genome-wide association (GWA) analysis was conducted to identify additional genomic regions that affect this trait.ResultsA total of 1883 animals were phenotyped for the number of ribs and thoracolumbar vertebrae as well as successfully genotyped with the Illumina Porcine SNP60 BeadChip. After data editing, 41,148 SNP markers were included in the GWA analysis. These animals were also phenotyped for kyphosis. Fifty-three 1 Mb windows each explained at least 1.0 % of the genomic variation for vertebrae counts while 16 regions were significant for kyphosis. Vertnin genotype significantly affected vertebral counts as well. The region with the largest effect for number of lumbar vertebrae and thoracolumbar vertebrae were located over the Hox B gene cluster and the largest association for thoracic vertebrae number was over the Hox A gene cluster. Genetic markers in significant regions accounted for approximately 50 % of the genomic variation. Less genomic variation for kyphosis was described by QTL regions and no region was associated with kyphosis and vertebra counts.ConclusionsThe importance of the Hox gene families in vertebral development was highlighted as significant associations were detected over the A, B and C families. Further evaluation of these regions and characterization of variants within these genes will expand our knowledge on vertebral development using natural genetic variants segregating in commercial swine.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0286-9) contains supplementary material, which is available to authorized users.

Pedicle Screw Fixation Study in Immature Porcine Spines to Improve Pullout Resistance during Animal Testing

The porcine model is frequently used during development and validation of new spinal devices, because of its likeness to the human spine. These spinal devices are frequently composed of pedicle screws with a reputation for stable fixation but which can suffer pullouts during preclinical implantation on young animals, leading to high morbidity. With a view to identifying the best choices to optimize pedicle screw fixation in the porcine model, this study evaluates ex vivo the impact of weight (age) of the animal, the level of the vertebrae (lumbar or thoracic) and the type of screw anchorage (mono- or bi-cortical) on pedicle screw pullouts. Among the 80 pig vertebrae (90- and 140-day-old) tested in this study, the average screw pullout forces ranged between 419.9N and 1341.2N. In addition, statistical differences were found between test groups, pointing out the influence of the three parameters stated above. We found that the the more caudally the screws are positioned (lumbar level), the greater their pullout resistance is, moreover, screw stability increases with the age, and finally, the screws implanted with a mono-cortical anchorage sustained lower pullout forces than those implanted with a bi-cortical anchorage. We conclude that the best anchorage can be obtained with older animals, using a lumbar fixation and long screws traversing the vertebra and inducing bi-cortical anchorage. In very young animals, pedicle screw fixations need to be bi-cortical and more numerous to prevent pullout.

Quantitative trait loci for the number of vertebrae on Sus scrofa chromosomes 1 and 7 independently influence the numbers of thoracic and lumbar vertebrae in pigs

Although quantitative trait loci (QTLs) for number of thoracic-lumbar vertebrae have been identified on Sus scrofa chromosomes (SSCs) 1 and 7, the influence of these QTLs on the thoracic and lumbar vertebrae is not clear. The aim of this study was to identify single nucleotide polymorphisms (SNPs) associated with total number of thoracic-lumbar vertebrae and for each trait (number of thoracic and lumbar vertebrae) separately. A total of 581 individuals from an F2 Large White×Minzhu population were genotyped using an SNP60K chip. Performing a genome-wide association study (GWAS) for total number of thoracic-lumbar vertebrae, 38 significant SNPs were identified in two QTL regions located on SSC1 and SSC7. Performing a GWAS for number of thoracic vertebrae only, 72 significant SNPs were located on SSC7. While performing a GWAS for number of lumbar vertebrae only, 17 significant SNPs were identified on SSC1. Gene mining suggested that the gene encoding orphan nuclear receptor, germ cell nuclear factor (NR6A1) on SSC1 was a strong candidate affecting the number of lumbar vertebrae in pigs. Additionally, genes encoding vertnin (VRTN), prospero homeobox 2 (PROX2), Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog (FOS), and transforming growth factor beta 3 (TGFB3) may be important candidates affecting the number of thoracic vertebrae in pigs. QTLs on SSC1 and SSC7 independently influenced the numbers of thoracic and lumbar vertebrae. These results shed light on the complex genetic background of vertebrae development in pigs.

Electrospun Nanofibrous P(DLLA-CL) Balloons as Calcium Phosphate Cement Filled Containers for Bone Repair: in Vitro and in Vivo Studies.

The spinal surgeon community has expressed significant interest in applying calcium phosphate cement (CPC) for the treatment of vertebral compression fractures (VCFs) and minimizing its disadvantages, such as its water-induced collapsibility and poor mechanical properties, limiting its clinical use. In this work, novel biodegradable electrospun nanofibrous poly(d,l-lactic acid-ϵ-caprolactone) balloons (ENPBs) were prepared, and the separation, pressure, degradation, and new bone formation behaviors of the ENPBs when used as CPC-filled containers in vitro and in vivo were systematically analyzed and compared. CPC could be separated from surrounding bone tissues by ENPBs in vitro and in vivo. ENPB-CPCs (ENPBs serving as CPC-filled containers) exerted pressure on the surrounding bone microenvironment, which was enough to crush trabecular bone. Compared with the CPC implantation, ENPB-CPCs delayed the degradation of CPC (i.e., its water-induced collapsilibity). Finally, possible mechanisms behind the in vivo effects caused by ENPB-CPCs implanted into rabbit thighbones and pig vertebrae were proposed. This work suggests that ENPBs can be potentially applied as CPC-filled containers in vivo and provides an experimental basis for the clinical application of ENPBs for the treatment of VCFs. In addition, this work will be of benefit to the development of polymer-based medical implants in the future.

3:54 PM Abstract No. 55 - Irreversible electroporation (IRE) ablation of the lumbar vertebrae in a porcine model: a correlation of clinical, radiologic and pathologic findings

Purpose To evaluate the effects of IRE ablation of the lumbar vertebrae in pigs. Materials and Methods Sixteen CT-guided IRE ablations [transpedicular location, (n=8 vertebrae) and directly over the posterior cortex (n=8 vertebrae)] were performed in the lumbar vertebrae of 8 pigs. Magnetic resonance imaging (MRI) was obtained immediately prior to euthanasia at 2 or 7-days postablation. Clinical, imaging and histopathological data were analyzed. The maximum length and width of the ablation zone was measured on the T2 and T1 + contrast MRI sequences and compared with histopatholgic measurements. Miller’s low-bias back-transformation was used to construct 95% confidence intervals for the mean absolute percent difference using square root transformed data. Results IRE probe placement and ablation was successful in all cases. The mean distances from the IRE probe to the posterior wall of vertebral body or the exiting nerve root were 2.93 ± 0.77 mm and 7.87 ± 1.99 mm respectively. None of the animals had neurologic deficits or MRI findings of focal myelopathy or radiculopathy. Well delineated areas of necrosis of bone marrow and bone tissues, and acute degeneration and necrosis of skeletal muscle adjacent to the vertebral body were present. These lesions were associated with tissue repair changes in the 7-day postablation animals. Four of 8 ablations in the transpedicular group and 3 of 8 ablations in the posterior cortex group had minimal to moderate acute degenerative lesions of adjacent nerve roots that were not clinically significant. The absolute percent difference of ablation measurements between MRI sequences and histopathological lesions showed an average error range of 24.2-28.8% [95% CI: (12.2%, 47.3%)] on T2 and 26.1-33.3% [95% CI: (15.1%, 52.6%)] on T1+contrast sequences. Conclusion IRE ablation of the lumbar vertebrae in pigs is feasible, safe, and produces localized necrosis of the bone, bone marrow and muscle tissues. No neurological clinical symptoms were associated with this procedure. MRI signal changes are not accurate indicators of the ablation zone when compared with histopathologic findings.

Identification of a second gene associated with variation in vertebral number in domestic pigs

BackgroundThe number of vertebrae in pigs varies and is associated with body size. Wild boars have 19 vertebrae, but European commercial breeds for pork production have 20 to 23 vertebrae. We previously identified two quantitative trait loci (QTLs) for number of vertebrae on Sus scrofa chromosomes (SSC) 1 and 7, and reported that an orphan nuclear receptor, NR6A1, was located at the QTL on SSC1. At the NR6A1 locus, wild boars and Asian local breed pigs had the wild-type allele and European commercial-breed pigs had an allele associated with increased numbers of vertebrae (number-increase allele).ResultsHere, we performed a map-based study to define the other QTL, on SSC7, for which we detected genetic diversity in European commercial breeds. Haplotype analysis with microsatellite markers revealed a 41-kb conserved region within all the number-increase alleles in the present study. We also developed single nucleotide polymorphisms (SNPs) in the 450-kb region around the QTL and used them for a linkage disequilibrium analysis and an association study in 199 independent animals. Three haplotype blocks were detected, and SNPs in the 41-kb region presented the highest associations with the number of vertebrae. This region encodes an uncharacterized hypothetical protein that is not a member of any other known gene family. Orthologs appear to exist not only in mammals but also birds and fish. This gene, which we have named vertnin (VRTN) is a candidate for the gene associated with variation in vertebral number. In pigs, the number-increase allele was expressed more abundantly than the wild-type allele in embryos. Among candidate polymorphisms, there is an insertion of a SINE element (PRE1) into the intron of the Q allele as well as the SNPs in the promoter region.ConclusionsGenetic diversity of VRTN is the suspected cause of the heterogeneity of the number of vertebrae in commercial-breed pigs, so the polymorphism information should be directly useful for assessing the genetic ability of individual animals. The number-increase allele of swine VRTN was suggested to add an additional thoracic segment to the animal. Functional analysis of VRTN may provide novel findings in the areas of developmental biology.

Fine mapping of a swine quantitative trait locus for number of vertebrae and analysis of an orphan nuclear receptor, germ cell nuclear factor (NR6A1)

The number of vertebrae in pigs varies and is associated with meat productivity. Wild boars, which are ancestors of domestic pigs, have 19 vertebrae. In comparison, European commercial breeds have 21-23 vertebrae, probably owing to selective breeding for enlargement of body size. We previously identified two quantitative trait loci (QTL) for the number of vertebrae on Sus scrofa chromosomes (SSC) 1 and 7. These QTL explained an increase of more than two vertebrae. Here, we performed a map-based study to define the QTL region on SSC1. By using three F2 experimental families, we performed interval mapping and recombination analyses and defined the QTL within a 1.9-cM interval. Then we analyzed the linkage disequilibrium of microsatellite markers in this interval and found that 10 adjacent markers in a 300-kb region were almost fixed in European commercial breeds. Genetic variation of the markers was observed in Asian local breeds or wild boars. This region encoded an orphan nuclear receptor, germ cell nuclear factor (NR6A1, formerly known as GCNF), which contained an amino acid substitution (Pro192Leu) coincident with the QTL. This substitution altered the binding activity of NR6A1 to its corepressors, nuclear receptor-associated protein 80 (RAP80) and nuclear receptor corepressor 1 (NCOR1). In addition, somites of mouse embryos demonstrated expression of NR6A1 protein. Together, these results suggest that NR6A1 is a strong candidate for one of the QTL that influence number of vertebrae in pigs.

The Effect of Pedicle Expansion on Pedicle Morphology and Biomechanical Stability in the Immature Porcine Spine

Biomechanical study in an animal model. To evaluate the feasibility of sequential dilation of the immature pedicles by dilators and to determine the biomechanical stability of screws placed in these expanded pedicles. Pedicle screws have become the implant of choice in spinal fixation. Secondary to the small vertebra sizes of pediatric patients and difficulty in finding appropriate screw sizes, they have found limited use in pediatric spine. Dilation of the pediatric pedicles may overcome the limitation secondary to discrepancy between screw sizes. However, there are no data in the literature regarding dilation capacity of pediatric pedicles to enable larger pedicle screw fixation. Two-month-old domestic pig vertebrae were used. The right pedicles were dilated with stainless steel dilators just before there is visual evidence of pedicle failure. The left pedicles served as a control group. The inner and outer diameters of the pedicles were measured on the CT scans before and after dilation. The pedicles were instrumented with 3.5-mm pedicle screws at the thoracic level and 4.0-mm pedicle screws at the lumbar level. The pullout strength of each pedicle was measured. The dilation procedure resulted in an increase in both inner (2.59 +/- 0.75 to 3.32 +/- 0.58 mm) and outer diameters (5.43 +/- 0.95 to 6.21 +/- 0.96 mm) (P < 0.05). The inner diameters dilated more than the outer diameters (34.3% vs. 15.0%). The pullout strength of the expanded pedicles (320.1 +/- 83.9 N) was significantly lower than the nonexpanded ones (408.1 +/- 102.0 N) (P < 0.01). This study demonstrated that immature pedicles can be expanded by application of serial dilators. However, dilation significantly decreases the pullout strength of the pedicle.

Nanostructure of the neurocentral growth plate: Insight from scanning small angle X-ray scattering, atomic force microscopy and scanning electron microscopy

In this study, the experimental techniques scanning electron microscopy (SEM) including energy-dispersive X-ray analysis, atomic force microscopy (AFM) and scanning small angle X-ray scattering (SAXS) have been exploited to characterize the organization of large molecules and nanocrystallites in and around the neurocentral growth plate (NGP) of a pig vertebrae L4. The techniques offer unique complementary information on the nano- to micrometer length scale and provide new insight in the changes in the matrix structure during endochondral bone formation. AFM and SEM imaging of the NGP reveal a fibrous network likely to consist of collagen type II and proteoglycans. High-resolution AFM imaging shows that the fibers have a diameter of approximately 100 nm and periodic features along the fibers with a periodicity of 50–70 nm. This is consistent with the SAXS analysis that yields a cross-sectional diameter of the fibers in the range of 90 to 112 nm and a predominant orientation in the longitudinal direction of the NGP. Furthermore, we find inhomogeneities around 7 nm in the NGP by SAXS analysis. Moving towards the bone in the direction perpendicular to the growth plate, a systematic change in apparent thickness is observed, while the large-scale structural features remain constant. In the region of bone, the apparent thickness equals the mean mineral thickness and increases from 2 nm to approximately 3.5 nm as a function distance from the NGP. The mineral particles are organized as plates in a rather compact network structure. We have demonstrated that SEM, AFM and SAXS are valuable tools for the investigation of the organization of large molecules and nanocrystallites in the NGP and adjacent trabecular bone. Our findings will be an important basis for future work into identifying the defects on nanometer length scale responsible for idiopathic scoliosis and other growth-plate-related diseases.

Analysis of two quantitative trait loci (QTL) for the number of vertebrae in pigs

Analysis of two quantitative trait loci (QTL) for the number of vertebrae in pigs

Laparoscopic approaches to the lumbar vertebrae. An anatomic study using a porcine model.

This study described and compared retroperitoneal and transperitoneal laparoscopic approaches to the lumbar vertebrae in pigs. Technical and perioperative complications were evaluated for each approach. The objective of this study was to develop a laparoscopic approach to the lumbar vertebrae that is associated with minimal technical and perioperative complications. Laparoscopic techniques have been used extensively in many surgical fields. Recently, thoracoscopy has been used to perform a number of thoracic spinal procedures, including thoracic discectomy, and anterior osteotomy, release, and fusion. To date, there have been no published reports describing laparoscopic approaches to the lumbar vertebrae. With all pigs positioned in left lateral recumbency, retroperitoneal and transperitoneal laparoscopic approaches to the lumbar vertebrae were performed in three pigs. Placement of the insufflation needles and trocar ports were determined for each approach. Dissection of the lumbar vertebrae were performed, and the technical and perioperative complications recorded. Radio-opaque markers were placed to identify the dissected lumbar intervertebral disc spaces, and intraoperative fluoroscopy was used to confirm marker placement. Gross anatomic dissections were performed after the pigs were killed. Loss of pneumoretroperitoneum resulted in surgical termination in two of three pigs undergoing retroperitoneal laparoscopic approach to the lumbar vertebrae. In the remaining pig, difficulty was encountered in mobilization of the psoas major muscle from the lumbar vertebrae, and significant bleeding occurred. The transperitoneal approach to the lumbar vertebrae resulted in rapid mobilization of the psoas musculature and exposure of the lumbar vertebral bodies and discs of L1-L6/L7. Intraoperative complications included minimal bleeding and difficulty encountered in mobilization of the renal vascular pedicle. The retroperitoneal approach was difficult because of the degree of muscle dissection required for exposure of the lumbar vertebrae. Complications associated with the retroperitoneal approach included loss of pneumoretroperitoneum because of entry into the peritoneal cavity, hemorrhage, and limited exposure of the lumbar vertebrae. The transperitoneal approach was easier technically, allowing identification and access to lumbar vertebral bodies and intervertebral discs from L1-L6/L7. Operative complications associated with the transperitoneal laparoscopic approach were minimal.

Effect of epidural analgesia on immediate posttraumatic cardiovascular hemodynamics and pulmonary platelet trapping.

Immediate reactions to different types of trauma have been the object of several studies recently. Thus, it has been shown that pulmonary platelet trapping (PPT) occurs within minutes after both septic and traumatic shock following soft tissue trauma. To study whether block of the nervous supply to the traumatized tissue had any effect on PPT, 40 mg of mepivacaine was injected through an epidural catheter inserted between the second and third lumbar vertebrae in pigs. After a period of stabilization the animals were subjected to a standardized soft tissue trauma to the hind limbs. A group of animals without an epidural catheter served as control. The trauma induced a profound decrease in cardiac output and mean arterial pressure. Pulmonary platelet trapping was recorded dynamically by labelling platelets with radioactive indium. Trapping of platelets in the lungs occurred immediately after the trauma, and there was no difference in animals pretreated with epidural block compared with the control animals. Our findings indicate that the trapping of platelets after soft tissue trauma is triggered at the trauma site and not affected by a block of the nervous supply to the trauma sites, including the peripheral sympathetic outflow.