Osseointegration of hollow cylinder based spinal implants in normal and osteoporotic vertebrae: a sheep study

INTRODUCTION: Osteoporosis is not only responsible for an increased number of metaphyseal and spinal fractures but it also complicates their treatment. To prevent the initial loosening, we developed a new implant with an enlarged implant/bone interface based on the concept of perforated, hollow cylinders. We evaluated whether osseointegration of a hollow cylinder based implant takes place in normal or osteoporotic bone of sheep under functional loading conditions during anterior stabilization of the lumbar spine. MATERIALS AND METHODS: Osseointegration of the cylinders and status of the fused segments (ventral corpectomy, replacement with iliac strut, and fixation with testing implant) were investigated in six osteoporotic (age 6.9 +/- 0.8 years, mean body weight 61.1 +/- 5.2 kg) and seven control sheep (age 6.1 +/- 0.2 years, mean body weight 64.9 +/- 5.7 kg). Osteoporosis was introduced using a combination protocol of ovariectomy, high-dose prednisone, calcium and phosphor reduced diet and movement restriction. Osseointegration was quantified using fluorescence and conventional histology; fusion status was determined using biomechanical testing of the stabilized segment in a six-degree-of-freedom loading device as well as with radiological and histological staging. RESULTS: Intact bone trabeculae were found in 70% of all perforations without differences between the two groups (P = 0.26). Inside the cylinders, bone volume/total volume was significantly higher than in the control vertebra (50 +/- 16 vs. 28 +/- 13%) of the same animal (P<0.01), but significantly less (P<0.01) than in the near surrounding (60 +/- 21%). After biomechanical testing as described in Sect. "Materials and methods", seven spines (three healthy and four osteoporotic) were classified as completely fused and six (four healthy and two osteoporotic) as not fused after a 4-month observation time. All endplates were bridged with intact trabeculae in the histological slices. CONCLUSIONS: The high number of perforations, filled with intact trabeculae, indicates an adequate fixation; bridging trabeculae between adjacent endplates and tricortical iliac struts in all vertebrae indicates that the anchorage is adequate to promote fusion in this animal model, even in the osteoporotic sheep.

Ovine Enzootic Abortion (OEA): a comparison of antibody responses in vaccinated and naturally-infected swiss sheep over a two year period

BACKGROUND: Prevention and control of ovine enzootic abortion (OEA) can be achieved by application of a live vaccine. In this study, five sheep flocks with different vaccination and infection status were serologically tested using a competitive enzyme-linked immunosorbent assay (cELISA) specific for Chlamydophila (Cp.) abortus over a two-year time period. RESULTS: Sheep in Flock A with recent OEA history had high antibody values after vaccination similar to Flock C with natural Cp. abortus infections. In contrast, OEA serology negative sheep (Flock E) showed individual animal-specific immunoreactions after vaccination. Antibody levels of vaccinated ewes in Flock B ranged from negative to positive two and three years after vaccination, respectively. Positive antibody values in the negative control Flock D (without OEA or vaccination) are probably due to asymptomatic intestinal infections with Cp. abortus. Excretion of the attenuated strain of Cp. abortus used in the live vaccine through the eye was not observed in vaccinated animals of Flock E. CONCLUSION: The findings of our study indicate that, using serology, no distinction can be made between vaccinated and naturally infected sheep. As a result, confirmation of a negative OEA status in vaccinated animals by serology cannot be determined.

Percutaneous vein occlusion with small intestinal submucosa: an experimental pilot study in Swine and sheep

PURPOSE: The objective of this study was to investigate the feasibility, outcomes, and amount of small intestinal submucosa (SIS) material needed for embolization of jugular vein (JV) in a swine and sheep model. Our hypothesis was that SIS would cause vein occlusion. MATERIALS AND METHODS: The external JVs (EJV) in swine (n = 6) and JVs in sheep (n = 6) were occluded with SIS fan-folded compressed strips. After percutaneous puncture of the peripheral portion of the EJV or JV, a TIPS set was used to exit their lumen centrally through the skin. The SIS strips were delivered into the isolated venous segment with a pull-through technique via a 10-Fr sheath. Follow-up venograms were done immediately after placement and at the time of sacrifice at 1 or 3 months. Gross examinations focused on the EJV or JV and their surrounding structures. Specimens were evaluated by histology. RESULTS: SIS strip(s) placement was successful in all cases, with immediate vein occlusion seen in 23 of 24 veins (95.8%). All EJVs treated with two strips and all JVs treated with three or four strips remained closed on 1- and 3-month follow-up venograms. Two EJVs treated with one strip and one JV treated with two strips were partially patent on venograms at 1 and 3 months. There has been one skin inflammatory reaction. Necropsies revealed excluded EJV or JV segments with SIS incorporation into the vein wall. Histology demonstrated various stages of SIS remodeling with fibrocytes, fibroblasts, endothelial cells, capillaries, and inflammatory cells. CONCLUSION: We conclude that EJV and JV ablation with SIS strips using percutaneous exit catheterization is feasible and effective in animal models. Further exploration of SIS as vein ablation material is recommended.

Ability of dGEMRIC and T2 mapping to evaluate cartilage repair after microfracture: a goat study

OBJECTIVE: To investigate the ability of delayed gadolinium-enhanced magnetic resonance (MR) imaging of cartilage (dGEMRIC) and T2 mapping to evaluate the quality of repair tissue after microfracture. DESIGN: Twelve knees from 12 goats were studied. An osteochondral defect (diameter, 6mm; depth, 3mm) with microfracture was created in the weight-bearing aspect of both the medial and lateral femoral condyles. Goats were euthanized at 24 weeks (n=6) and 48 weeks (n=6) postsurgery. Pre-contrast R1 (R1pre) and post-contrast R1 (R1post) measurements for dGEMRIC and a pre-contrast T2 measurement for T2 mapping were performed with a 3T MR imaging system. MR imaging findings were compared with histological and biochemical assessments. RESULTS: In native cartilage, significant correlations were observed between the R1post and the glycosaminoglycan (GAG) concentration, as well as DeltaR1 (difference between the R1pre and R1post) and the GAG concentration (P<0.05). In repair tissue, a significant correlation was observed between DeltaR1 and the GAG concentration (P<0.05), but not between the R1post and the GAG concentration. In both repair tissue and native cartilage, no correlation was observed between T2 and the water concentration or between T2 and the hydroxyproline (HP) concentration. A zonal variation of T2 and a clear dependence of T2 on the angles relative to B0 were observed in native cartilage, but not in repair tissue. CONCLUSION: dGEMRIC with DeltaR1 measurement might be useful for the evaluation of the GAG concentration in repair tissue after microfracture. T2 mapping might be useful for the differentiation of repair tissue after microfracture from native cartilage; however, its potential to assess the specific biochemical markers in native cartilage as well as repair tissue may be limited.

Adipogenic and myogenic gene expression in rotator cuff muscle of the sheep after tendon tear

Chronic rotator cuff tendon tears lead to fatty infiltration and muscle atrophy with impaired physiological functions of the affected muscles. However, the cellular and molecular mechanisms of corresponding pathophysiological processes remain unknown. The purpose of this study was to characterize the expression pattern of adipogenic (PPARgamma, C/EBPbeta) and myogenic (myostatin, myogenin, Myf-5) transcription factors in infraspinatus muscle of sheep after tenotomy, implantation of a tension device, refixation of the tendon, and rehabilitation, reflecting a model of chronic rotator cuff tears. In contrast to human patients, the presented sheep model allows a temporal evaluation of the expression of a given marker in the same individual over time. Semiquantitative RT/PCR analysis of PPARgammaã, myostatin, myogenin, Myf-5, and C/EBPbeta transcript levels was carried out with sheep muscle biopsy-derived total RNA. We found a significantly increased expression of Myf-5 and PPARgamma after tenotomy and a significant change for Myf-5 and C/EBPbeta after continuous traction and refixation. This experimental sheep model allows the molecular analysis of pathomechanisms of muscular changes after rotator cuff tear. The results point to a crucial role of the transcription factors PPARgamma, C/EBPbeta, and Myf-5 in impairment and regeneration of rotator cuff muscles after tendon tears in sheep.

Molecular genetic analysis of Dichelobacter nodosus proteases AprV2/B2, AprV5/B5 and BprV/B in clinical material from European sheep flocks

Dichelobacter nodosus, the etiological agent of ovine footrot, exists both as virulent and as benign strains, which differ in virulence mainly due to subtle differences in the three subtilisin-like proteases AprV2, AprV5 and BprV found in virulent, and AprB2, AprB5 and BprB in benign strains of D. nodosus. Our objective was a molecular genetic epidemiological analysis of the genes of these proteases by direct sequence analysis from clinical material of sheep from herds with and without history of footrot from 4 different European countries. The data reveal the two proteases known as virulent AprV2 and benign AprB2 to correlate fully to the clinical status of the individuals or the footrot history of the herd. In samples taken from affected herds, the aprV2 gene was found as a single allele whereas in samples from unaffected herds several alleles with minor modifications of the aprB2 gene were detected. The different alleles of aprB2 were related to the herds. The aprV5 and aprB5 genes were found in the form of several alleles scattered without distinction between affected and non-affected herds. However, all different alleles of aprV5 and aprB5 encode the same amino acid sequences, indicating the existence of a single protease isoenzyme 5 in both benign and virulent strains. The genes of the basic proteases BprV and BprB also exist as various alleles. However, differences found in samples from affected versus non-affected herds do not reflect the currently known epitopes that are attributed to differences in biochemical activity. The data of the study confirm the prominent role of AprV2 in the virulence of D. nodosus and shed a new light on the presence of the other protease genes and their allelic variants in clinical samples.

Investigation of border disease and bovine virus diarrhoea in sheep from 76 mixed cattle and sheep farms in eastern Switzerland

The purpose of this study was to examine the occurrence of sheep persistently infected with Border disease virus (BDV) on 76 mixed cattle and sheep farms and whether seroconversion to BDV infection occurred in cattle of these farms. Seroprevalence of BDV and bovine viral disease virus (BVDV) infection in sheep was also investigated. Quantitative RT-PCR for pestivirus detection and an ELISA to detect pestivirus antibodies were used in 2'384 and 2'291 ovine blood samples, respectively. Another 27 seropositive sheep from ten flocks underwent serum neutralization testing to differentiate between BDV and BVDV antibodies. A BDV titre that was at least four times higher than the BVDV titre was interpreted as the result of BDV infection. Titres against BVDV were interpreted in an analogous fashion. All examined sheep were pestivirus-negative, 310 sheep were seropositive, 119 had an indeterminate titre and 1'862 were seronegative. The flock seroprevalence ranged from 0.0 to 73.9 %. Three of the 27 flocks that underwent serum neutralization testing were interpreted as BDV-infected because of 6 sheep with higher BDV titres, and 6 flocks were interpreted as BVDV-infected because of 14 sheep with higher BVDV titres.

Virological and phylogenetic characterization of attenuated small ruminant lentivirus isolates eluding efficient serological detection

Three field isolates of small ruminant lentiviruses (SRLVs) were derived from a mixed flock of goats and sheep certified for many years as free of caprine arthritis encephalitis virus (CAEV). The phylogenetic analysis of pol sequences permitted to classify these isolates as A4 subtype. None of the animals showed clinical signs of SRLV infection, confirming previous observations which had suggested that this particular subtype is highly attenuated, at least for goats. A quantitative real time PCR strategy based on primers and probes derived from a highly variable env region permitted us to classify the animals as uninfected, singly or doubly infected. The performance of different serological tools based on this classification revealed their profound inadequacy in monitoring animals infected with this particular SRLV subtype. In vitro, the isolates showed differences in their cytopathicity and a tendency to replicate more efficiently in goat than sheep cells, especially in goat macrophages. By contrast, in vivo, these viruses reached significantly higher viral loads in sheep than in goats. Both env subtypes infected goats and sheep with equal efficiency. One of these, however, reached significantly higher viral loads in both species. In conclusion, we characterized three isolates of the SRLV subtype A4 that efficiently circulate in a mixed herd of goats and sheep in spite of their apparent attenuation and a strict physical separation between goats and sheep. The poor performance of the serological tools applied indicates that, to support an SRLV eradication campaign, it is imperative to develop novel, subtype specific tools.

Sheep wool in Bronze and Iron Age Europe

This study presents the results of a series of wool measurements from Bronze Age and Iron Age skins and textiles from Hallstatt, and Bronze Age textiles from Scandinavia and the Balkans. A new method of classification that was set up and applied on mostly mineralised Iron Age material has now been applied to a large body of non-mineralised material from the Bronze and Iron Ages. Three types of microscopes were used and their advantages and disadvantages assessed. The results of the investigation cast new light on sheep breeding and fibre processing in prehistoric Europe, and suggest that different sheep breeds existed in Bronze Age Europe.