The piglet as a model for B cell and immune system development.

The ability to identify factors responsible for disease in all species depends on the ability to separate those factors which are environmental from those that are intrinsic. This is particularly important for studies on the development of the adaptive immune response of neonates. Studies on laboratory rodents or primates have been ambiguous because neither the effect of environmental nor maternal factors on the newborn can be controlled in mammals that: (i) transmit potential maternal immunoregulatory factors in utero and (ii) are altricial and cannot be reared after birth without their mothers. Employing the newborn piglet model can address each of these concerns. However, it comes at the price of having first to characterize the immune system of swine and its development. This review focuses on the porcine B cell system, especially on the methods used for its characterization in fetal studies and neonatal piglets. Understanding these procedures is important in the interpretation of the data obtained. Studies on neonatal piglets have (a) provided valuable information on the development of the adaptive immune system, (b) lead to important advances in evolutionary biology, (c) aided our understanding of passive immunity and (d) provided opportunities to use swine to address specific issues in veterinary and biomedical research and immunotherapy. This review summarizes the history of the development of the piglet as a model for antibody repertoire development, thus providing a framework to guide future investigators.

Validation and comparison of three enzyme-linked immunosorbent assays for the detection of antibodies to Cowdria ruminantium infection.

Serological tests for Cowdria ruminantium infection have been hampered by low specificity. Here, an indirect ELISA based on purified antigen, a competitive ELISA using a recombinant major antigenic protein (MAP-1) and an indirect ELISA based on the MAP-1B region of the recombinant MAP-1 were compared. The tests were validated using 3000 sera of ruminants from 14 islands of the Lesser Antilles as well as sequential serum samples from 10 cattle, 17 goats and 10 sheep vaccinated with inactivated C. ruminantium in ISA 50 adjuvant and from 14 goats infected with a virulent culture supernatant. All tests detected significantly higher percentages of positives on Antigua, Guadeloupe and Marie-Galante, where C. ruminantium had been isolated before. Overall specificity calculated with sera from the other 11 heartwater-free islands was 98.1%, 98.5%, and 99.4% for the ELISA based on crude antigen, recombinant MAP-1 and MAP-1B, respectively. Sensitivities observed with sequential serum samples were similar for all tests. Tests based on recombinant antigens, especially the MAP-1B, showed improved specificity, suggesting their use for epidemiological studies in regions where the distribution of cowdriosis is unknown. In addition, the competitive ELISA is useful for studies in wildlife for which species-specific conjugates do not exist.

Roentgenographic evaluation of vertebral rotation.

To examine the accuracy of vertebral rotation determinations made from roentgenographic pedicle-shadow offset measurements, roentgenograms were made of fifteen cadaver vertebrae with different sagittal and frontal inclinations and longitudinal axis rotations ranging from 15 degrees left to 45 degrees right. It was found that significant uncertainties arise when vertebral rotation is evaluated from measurements of pedicle-shadow offset: true and apparent offsets in a single vertebra differ markedly; vertebrae from different spines have different offsets for the same degree of rotation and the same inclinations; and changes in the sagittal and frontal inclinations of a single vertebra alter its offset in the same manner as changes in rotation. From these results, it seems unlikely that precise measurements of rotation changes in spines with mild or moderate scolioses, for example, can be made from anteroposterior roentgenograms.

Milwaukee brace correction of idiopathic scoliosis. A biomechanical analysis and a restrospective study.

We analyzed the biomechanics of Milwaukee brace treatment of idiopathic scoliotic patients through simulation in five computer-constructed model spines. The contributions to correction of each component of the brace were examined in these model spines, and some of the mechanical principles that determine the outcome of brace treatment were studied. The validity of the stimulation findings was then tested by a retrospective analysis. Simulation was used to predict the outcome of milwaukee brace treatment in sixty-eight patients. In 81 per cent of these patients, the actual outcome agreed with the prediction. The study suggests that careful adherence to mechanical principles in the use of a Milwaukee brace will result in successful treatment of more patients.

Severe lumbosacral spondylolisthesis in adolescents and children. Reduction and staged circumferential fusion.

Using a new surgical regimen, fourteen patients with lumbosacral spondylolisthesis and more than 50 per cent slipping were treated by reduction of the slip with two Harrington distraction rods extending from the first lumbar laminae to the sacral alae and bilateral posterolateral fusion from the fourth lumbar to the second sacral segment. Then, at a second procedure, thirteen had an anterior lumbosacral fusion using two bicortical wedge-shaped iliac grafts. The distraction rods were removed six to twelve months later. At follow-up, correction of the slips ranged from 70 to 100 per cent. In four of the thirteen patients the reduction was improved by 10 to 13 per cent during the anterior procedure. In one patient, a twenty-one-year-old women with a slip of more than 100 per cent, a cauda equina syndrome developed after the reduction and posterolateral fusion, and this necessitated removal of th rods and cancellation of the anterior fusion. This patient recovered completely and her final result was a solid posterolateral fusion in situ, with her abnormal posture and gait unchanged. The other thirteen patients, after follow-up ranging from two years to six years and seven months, had solid fusion, normal spinal alignment, normal anatomy of the spinal canal, and normal posture and gait. Only one patient had loss of correction during follow-up, which amounted to 7 per cent. We concluded that correction of severe spondylolisthesis (50 per cent or more) in properly selected patients can be accomplished by this two-stage procedure without risk of further slipping, pseudarthrosis, persistent deformity, or recurrence of the slip due to late remodeling.

Controlled hypotensive anesthesia in scoliosis surgery.

In a retrospective study comparing normotensive (twenty-two patients) and controlled hypotensive (forty-four patients) anesthesia for spine fusion and Harrington instrumentation, the use of hypotensive anethesia was found to decrease the need for blood replacement and total blood loss by an average of 40 per cent and to reduce the average operating time by more than thirty minutes. No complications attributable to the anesthetic technique occured.

Simultaneous anterior and posterior surgical approach to the thoracic and lumbar spine.

A technique for the simultaneous anterior and posterior surgical approach to the thoracic and lumbar spine is presented. No intraoperative repositioning of the patient is required. The procedure requires a surgical team of two spinal surgeons and two assistant surgeons, as well as an anesthesiologist familiar with hypotensive techniques. The procedure as utilized in 14 cases has proven to be safe and expeditious. The simultaneous anteroposterior approach has proven to be especially useful in cases with combined anterior and posterior instability. The technique described provides the experienced spinal surgeon with the best solution to certain complex spinal problems.

Anterior and posterior spinal fusion for paralytic scoliosis.

Twenty-three patients with paralytic scoliosis were treated with a combination of anterior and posterior spinal instrumentation and fusion. The sequence was anterior surgery first in 19 patients and posterior surgery first in 4. The average age was 14.4 years. Preoperative correction with a halo-hoop apparatus was performed in 12 patients. The average preoperative curve for the group measured 100 degrees, and the average postoperative curve at a mean follow-up time of 21 months was 37 degrees. The mean loss of correction was 8 degrees. Although superior hook dislodgment occurred in 5 patients, no pseudarthrosis or beinding of the fusion mass was documented.

Sagittal plane configuration of the sacrum in spondylolisthesis.

STUDY DESIGN: A radiographic study of the sagittal sacral deformity in spondylolisthesis. OBJECTIVES: To characterize and classify the pathoanatomy of sagittal sacral deformation in spondylolisthesis. SUMMARY OF BACKGROUND DATA: Spondylolisthesis has been extensively described and reviewed in the literature. Deformity of the entire sacrum in spondylolisthesis potentially could affect the natural history, treatment options, and outcome. The sagittal contour of the entire human sacrum has never been quantitatively studied in spondylolisthesis. METHODS: A literature search was performed and data was gathered retrospectively on patients with spondylolisthesis at the authors' institution. Cases of degenerative spondylolisthesis were excluded. Specifically those patients with L5-S1 spondylolisthesis were studied. The authors studied standing lateral radiographs and performed statistical analysis to understand morphologic relations. RESULTS: A broad range of global sacral kyphosis (37-188 degrees ) exists in spondylolisthesis. Increasing sacral kyphosis is significantly associated with increasing percent slip, sacral horizontal angle, Neuman's classification, lumbar lordosis, and lumbar index. A simple classification of the spectrum of sacral deformity in the sagittal plane is presented. CONCLUSION: The entire sacrum in spondylolisthesis can develop a significant kyphotic deformity in the sagittal plane, and this is associated with other abnormalities found in the lumbosacral spine. Sacral deformity is a significant factor in the assessment of the sagittal contour of the patient with L5-S1 spondylolisthesis.

Reconstructive spinal surgery as palliation for metastatic malignancies of the spine.

Metastatic tumors of the spine often cause severe pain and paralysis because of deformity and neural encroachment. As oncology now extends the life expectancies of these patients, spinal decompression and stabilization is necessary. We consider that prophylactic stabilization of the spine is analogous to prophylactic nailing of a femur with a pathologic lesion. Both the femur and spine are weight-bearing structures. The advent of segmental instrumentation makes this a feasible accomplishment with minimal morbidity. Seventeen patients with metastatic disease of the spine at Rush-Presbyterian-St. Luke's Medical Center, Chicago, were reviewed. All maintained spinal stability postoperatively. Eleven of the 17 had significant pain relief for 3 months or more. Five of 11 paralyzed patients had significant neural recovery. A classification for treatment purposes regardless of tissue type was developed. Once classified, the surgical goals for these patients were to decrease pain, to preserve or to improve neurologic function and to mobilize the patient without external orthosis.

SRS travelling fellowship.

A 3-week tour of the Far East was coordinated by Dr. Ronald DeWald, senior travelling fellow appointed by the Scoliosis Research Society. Three junior fellows appointed by the Education Committee of the Scoliosis Research Society accompanied him. The purpose of this fellowship was to develop a comaraderie and exchange ideas, thoughts, and experiences in the field of spinal deformity.

An open, minimally invasive approach to the lumbar spine.

A minimum 2-year follow-up retrospective review was undertaken to assess our experience with an anterior paramedian muscle-sparing approach to the lumbar spine for anterior spinal fusion (ASF). The records of 28 patients (November 1991 through January 1996) undergoing ASF via a left lower quadrant transverse skin incision (6-10 cm) with a paramedian anterior rectus fascial Z-plasty retroperitoneal approach were reviewed. Diagnosis, number, and level of lumbar interspaces fused, types of fusion, estimated blood loss, length of procedure, length of hospital stay, and complications were analyzed. All cases were completed as either a same-day anterior/posterior (24 of 28) or as a staged procedure at least 1 week after posterior fusion (4 of 28). The General Surgery service performed the muscle-sparing approach, whereas the Orthopedic Spine service performed the ASF. There were 14 men and 14 women, with a mean age of 35.5 years (range, 11-52 years). Diagnoses included spondylolisthesis in 20 cases (including four grade III or IV slips), segmental instability (degenerative or postsurgical) in 7, and 1 flatback deformity. A single level was fused in 20 cases (L4/5 in 4 and L5/S1 in 16), two levels were fused in 5 cases (L4/5 and L5/S1) and three levels were fused in 2 cases (L3/4, L4/5, and L5/S1). The mean length of stay was 7.4 days (range, 5-12 days). The mean estimated blood loss was 300 mL for the anterior procedure alone and 700 ml for both anterior/posterior procedures on the same day. The mean length of operating room time for the anterior approach and fusion was 117 minutes (range, 60-330 minutes). Posterior instrumentation was used in all cases. Anterior interbody struts used included 19 autogenous tricortical grafts, 4 fresh-frozen allografts (2 femoral rings and 2 iliac crests), 3 carbon fiber cages packed with autogenous bone, and a Harms titanium cage with autograft. There was one L5 corpectomy for which a large tricortical allograft strut was utilized. There were no vascular, visceral, or urinary tract injuries. In three cases a mild ileus developed, which resolved spontaneously. We conclude that the anterior paramedian muscle-sparing retroperitoneal approach is safe, uses a small skin incision, avoids cutting abdominal wall musculature, and allows for multiple-level anterior spinal fusions by a variety of interbody fusion techniques. This approach does not require transperitoneal violation or added endoscopic instrumentation, nor does it limit fusion level and technique of fusion, as is the case with the recently popularized laparoscopic approach to the lumbar spine.

Procedurally similar competitive immunoassay systems for the serodiagnosis of Babesia equi, Babesia caballi, Trypanosoma equiperdum, and Burkholderia mallei infection in horses.

Procedurally similar competitive enzyme-linked immunoassay (cELISA) methods were developed for the serodiagnosis of Babesia equi and Babesia caballi (piroplasmosis), Trypanosoma equiperdum (dourine), and Burkholderia mallei (glanders) infections in horses. Apparent test specificities for the B. equi, B. caballi, T. equiperdum, and B. mallei cELISAs were 99.2%, 99.5%, 98.9%, and 98.9%, respectively. Concordances and kappa values between the complement fixation (CF) and the cELISA procedures for the serodiagnosis of B. equi, B. caballi, T. equiperdum, and B. mallei infections in experimentally exposed horses were 76% and 0.55, 89% and 0.78, 97% and 0.95, and 70% and 0.44, respectively. The cELISA method may be a technically more reproducible, objective, and convenient approach for piroplasmosis, dourine, and glanders serodiagnosis in qualifying animals for international movement and disease eradication programs than the CF systems currently in use. Use of the cELISA method also obviated the problems associated with testing hemolyzed or anticomplementary sera.

Development and evaluation of a recombinant antigen, monoclonal antibody-based competitive ELISA for heartwater serodiagnosis.

Cowdria ruminantium is the etiologic agent of heartwater, a tick-transmitted foreign animal disease with considerable potential for entrance into the USA. A competitive enzyme-linked immunosorbent assay (cELISA) was developed to detect serologic responses to C. ruminantium infection. The cELISA utilized a recombinant form of the C. ruminantium major antigenic protein (MAP-1) as the antigen and an anti-MAP-1 monoclonal antibody as the competing indicator reagent. Experimental antisera to C. ruminantium and a wide variety of related ehrlichial organisms were used to evaluate cELISA reactivity. Only sera against C. ruminantium, Ehrlichia canis, E. chaffeensis, and a recently discovered cervine ehrlichia-like organism reacted positively in the cELISA. Specificity of the cELISA was > or = 99.5% in a survey of 1,774 southeastern US and Puerto Rican slaughter cattle sera but was only 85% in a group of 79 hunter-killed white-tailed deer (Odocoileus virginianus) from the southeastern USA. Reference true-positive and cELISA false-positive sera were further analyzed by end point titrations using the cELISA and by indirect fluorescent antibody (IFA) tests for reactivity with C. ruminantium, E. canis, and E. chaffeensis antigens. True heartwater-positive sera were significantly more reactive using the cELISA and C. ruminantium IFA procedures (P < 0.05), whereas false-positive sera were significantly more reactive with the antigens used in the E. chaffeensis IFA procedure (P < 0.05). A group of sera from 210 field-origin ruminants residing on known or potentially heartwater-endemic Caribbean islands revealed a substantial (12.4%) prevalence of cELISA-positive specimens. The cELISA is a relatively specific serodiagnostic test for heartwater in cattle and could be used to monitor for possible introduction of the disease into the USA. The cELISA may also be an excellent tool for monitoring the success of an ongoing Caribbean Amblyomma tick eradication program designed to eliminate the biological vector responsible for the perpetuation and spread of this dangerous foreign animal disease.

Luque rod stabilization for metastatic disease of the spine.

Instability of the spine caused by metastatic spread of primary tumors represents a serious risk for spinal cord or nerve root compression. In order to restore stability and relieve neural compression, a variety of surgical techniques originally used for reduction of nonpathologic spinal fractures have been applied to the problem of spinal metastases. Recently, we have utilized a technique developed primarily for correction of scoliosis to the treatment of metastatic spinal fractures. Six patients with spinal instability and neural compression secondary to metastatic tumors had segmental spinal stabilization with Luque rods, sublaminar wiring, and methyl methacrylate. Restoration of stability was successful in all cases with alleviation of preoperative pain and return to full activity. No evidence of instability occurred in this group of patients. As demonstrated by this experience and that of a few other small series, Luque rod stabilization provides a valuable addition to the techniques available for stabilization of metastatic fractures of the spine. Although the precise role of Luque rod segmental spinal stabilization in treatment of metastatic disease of the spine continues to be defined, thus far it has proved beneficial for cases of multiple vertebral body involvement or instability beyond one vertebral level.

Zielke instrumentation.

Zielke modified Dwyer's anterior spinal instrumentation to produce the Ventral Derotational Spondylodesis (VDS) System. The primary indication for VDS instrumentation is the treatment of progressive, single, major lumbar or thoracolumbar curves in idiopathic scoliosis. The surgical technique, including selection of appropriate curvatures and levels of instrumentation, is described. A group of 25 consecutive patients undergoing VDS instrumentation for lumbar or thoracolumbar curvatures was reviewed. The average correction of the major curve was 76%. The minor curvature was corrected with an average of 47%. A significant complication was a 20% incidence of pseudarthrosis and rod breakage. The implications of these problems are discussed. Zielke instrumentation is a powerful technique for the correction of selected curves. The system provides greater correction of the major curve, improved frontal and sagittal alignment, and preservation of distal motion segments.