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.

Optimization of corticosteroid induced osteoporosis in ovariectomized sheep. A bone histomorphometric study

During osteoporosis induction in sheep, side effects of the steroids were observed in previous studies. The aim of this study was to improve the induction regimen consisting of ovariectomy, calcium/vitamin D- restricted diet and methylprednisolone (-MP)- medication with respect to the bone metabolism and to reduce the adverse side effects. Thirty-six ewes (age 6.5 +/- 0.6 years) were divided into four MP-administration groups (n = 9) with a total dose of 1800 mg MP: group 1: 20 mg/day, group 2: 60 mg/every third day, group 3: 3 x 500 mg and 1 x 300 mg at intervals of three weeks, group 4: weekly administration, starting at 70 mg and weekly reduction by 10 mg. After double-labelling with Calcein Green and Xylenol Orange, bone biopsy specimens were taken from the iliac crest (IC) at the beginning and four weeks after the last MP injection, and additionally from the vertebral body (VB) at the end of the experiment. Bone samples were processed into stained and fluorescent sections, static and dynamic measurements were performed. There were no significant differences for static parameters between the groups initially. The bone perimeter and the bone area values were significantly higher in the VB than in the IC (Pm: 26%, p < 0.0001, Ar: 11%, p < 0.0166). A significant decrease (20%) of the bone area was observed after corticosteroid-induced osteoporosis (p < 0.0004). For the dynamic parameters, no significant difference between the groups was found. Presence of Calcein Green and Xylenol Orange labels were noted in 50% of the biopsies in the IC, 100% in the VB. Group 3 showed the lowest prevalence of adverse side effects. The bone metabolism changes were observed in all four groups, and the VB bone metabolism was higher when compared to the IC. In conclusion, when using equal amounts of steroids adverse side effects can be reduced by decreasing the number of administrations without reducing the effect regarding corticosteroid-induced osteoporosis. This information is useful to reduce the discomfort of the animals in this sheep model of corticosteroid-induced osteoporosis.

Taxonomic position and geographical distribution of the common sheep G1 and camel G6 strains of Echinococcus granulosus in three African countries

The taxonomic and phylogenetic status of Echinococcus granulosus strains are still controversial and under discussion. In the present study, we investigated the genetic polymorphism of E. granulosus isolates originating from three countries of Africa, including a region of Algeria, where the common G1 sheep and the camel G6 strains coexist sympatrically. Seventy-one hydatid cysts were collected from sheep, cattle, camels, and humans. Two mitochondrial markers (cox1 and nad1) were used for strain identification. Two nuclear markers (actII and hbx2) were used to study the possible occurrence of cross-fertilization. Despite the heterogeneity observed among the G1 isolates, they were all localized within one robust cluster. A second strong cluster was also observed containing all of the G6 isolates. Both strains appeared as two distinct groups, and no cases of interbreeding were found. Thus, the attribution of a species rank can be suggested. We also found the Tasmanian sheep G2 strain for the first time in Africa. Because of the slight variations observed between the common sheep and the Tasmanian sheep strains, further studies should be carried out to elucidate the epidemiological relevance of this genetic discrimination.

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.

Biofilm responses to salmon carcass analog addition in central Idaho streams

Pacific salmon populations have declined due to human activity in the Pacific Northwest, resulting in decreased delivery of marine-derived nutrients to streams. Managers use artificial nutrient additions to increase juvenile salmon growth and survival and assume that added nutrients stimulate biofilm production, which propagates up the food web to juvenile salmon. We assessed biofilm responses (standing crop, nutrient limitation, and metabolism) to experimental additions of salmon carcass analog in tributaries of the Salmon River, Idaho in 2010 and 2011. Biofilm standing crop and nutrient limitation did not respond to analog, but primary productivity and respiration increased in the subset of streams where they were measured. Discrepancies between biofilm productivity and standing crop may occur if standing crop is constrained by physical and biological factors. Thus, conclusions about biofilm response to analog should not be based on standing crop alone and mitigation research may benefit from nutrient budgets of entire watersheds.

Ascorbic acid for amelioration of reperfusion injury in a lung autotransplantation model in sheep

BACKGROUND: Reperfusion injury is the leading cause of early graft dysfunction after lung transplantation. Activation of neutrophilic granulocytes with generation of free oxygen radicals appears to play a key role in this process. The efficacy of ascorbic acid as an antioxidant in the amelioration of reperfusion injury after lung transplantation has not been studied yet. METHODS: An in situ autotransplantation model in sheep is presented. The left lung was flushed (Euro-Collins solution) and reperfused; after 2 hours of cold storage, the right hilus was then clamped (group R [reference], n = 6). Group AA animals (n = 6) were treated with 1 g/kg ascorbic acid before reperfusion. Controls (group C, n = 6) underwent hilar preparation and instrumentation only. RESULTS: In group R, arterio-alveolar oxygen difference (AaDO2) and pulmonary vascular resistance (PVR) were significantly elevated after reperfusion. Five of 6 animals developed frank alveolar edema. All biochemical parameters showed significant PMN activation. In group AA, AaDO2, PVR, work of breathing, and the level of PMN activation were significantly lower. CONCLUSIONS: The experimental model reproduces all aspects of lung reperfusion injury reliably. Ascorbic acid was able to weaken reperfusion injury in this experimental setup.

Neer Award 2007: Reversion of structural muscle changes caused by chronic rotator cuff tears using continuous musculotendinous traction. An experimental study in sheep

HYPOTHESIS: Chronic rotator cuff tears are associated with irreversible architectural muscle changes and a high rate of repair failure. The changes observed in man and their irreversibility with a single stage repair can be reproduced in sheep. It was the purpose of this experiment to test the hypothesis that slow, continuous elongation of a retracted musculotendinous unit allows reversal of the currently irreversible structural muscle changes. MATERIALS AND METHODS: The infraspinatus tendon of 12 sheep was released using a greater tuberosity osteotomy and allowed to retract for 4 months. Then, a new device was mounted on the scapular spine and used to extend the infraspinatus muscuculotendinous unit transcutaneously by 1 mm per day. Thereafter, the tendon was repaired back to the greater tuberosity. We assessed the muscular architecture using magnetic resonance imaging, macroscopic dissection, histology, and electron microscopy. Fatty infiltration (in Hounsfield units 1/4 HU) and muscular cross-sectional area (in % of the control side) were monitored with computed tomography at tendon release, initiation of elongation, repair, and at sacrifice. RESULTS: Sixteen weeks after tendon release, the mean tendon retraction was 29 +/- 6 mm (14% of original length, P = .008). In 8 sheep, elongation was achieved as planned (group I), but in 4, the elongation failed technically (group II). The mean traction time was 24 +/- 6 days with a mean traction distance of 19 +/- 4 mm. At sacrifice, the mean pennation angle in the infraspinatus of group I was not different from the control side (29.8 degrees +/-7.5 degrees vs. 30 degrees +/-6 degrees , P = .575). In group II, the pennation angle had increased from 30 degrees +/-6 degrees to 55 degrees +/-14 degrees (P = .035). There was no fatty infiltration at the time of tendon release. After retraction, there was a significant increase in fatty infiltration of the infraspinatus muscle and a decrease of its cross-sectional area to 57% of the contralateral side (P = .0001). During traction, the degree of fatty infiltration remained unchanged (36 HU to 38 HU, P = .381), and atrophy improved to a muscle square area of 78% of the contralateral side (P = .0001) in group I. In group II, an increase of fatty infiltration was measured from 36 HU to 28 HU; however, this increase was not significant (P = .144). Atrophy did not change in group II (57-55%, P = .946). At sacrifice, the remaining muscle mass was 64% in group I and 46% in group II (P = .019). DISCUSSION: Our preliminary results document, that continuous elongation of a retracted, fatty infiltrated and atrophied musculotendinous unit is technically feasible. CONCLUSION: In the sheep, continuous elongation can lead to restoration of normal muscle architecture, to partial reversal of muscle atrophy, and to arrest of the progression of fatty infiltration. LEVEL OF EVIDENCE: Basic science level 2; Prospective comparative therapeutic study.

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.