Previous Fusion Research Articles

Does the Number of Levels Affect Lumbar Fusion Outcome?

Retrospective outcome measurement after circumferential reconstructive surgery with lumbar fusion in patients with chronic discogenic low back pain. To examine the effect of the number of fusion levels on surgical outcomes in patients with chronic discogenic low back pain using provocative pressure-controlled diskography as a primary diagnostic tool. Although there is general agreement that construct length adversely affects arthrodesis success rates, the effect of the number of levels on lumbar fusion surgery outcome has not been reported. Previous fusion outcome studies have generally relied on magnetic resonance imaging or conventional diskography for diagnosis. From 1994 through 2000, prospectively collected medical records of patients who underwent reconstructive lumbar spine surgery with confirmation of the pain generator by pressure-controlled diskography were retrospectively analyzed. Data were subdivided into 2 groups of patients. The first group, designated the short segment group, contained patients who underwent fusion at 1 or 2 levels. The second group, designated the long segment group, contained patients who underwent fusion at 3-5 levels. Surgical methods included circumferential reconstruction of the lumbar spine by either posterior or combined anterior and posterior approach. Surgeries included posterior decompression necessary to relieve documented regions of neural compression, combined with interbody arthrodesis at selective levels, augmented by posterior segmental spinal instrumentation and posterolateral arthrodesis. All patients completed a preoperative aquatic-conditioning program. Whenever possible, coexisting medical conditions were corrected or stabilized before surgery. A preoperative Short Form RAND 36-Item Health Survey (SF-36) was completed, and repeated at 1 and 2 years after surgery. The short and long segment groups contained 142 and 82 patients, respectively, who completed the preoperative SF-36 questionnaire completely. One hundred patients in the short segment group (vide infra) were available for 1-year follow-up, and68 were available for 2-year follow-up. In the long segment group, 81 patients were available for 1-year follow-up, and 49 were available for 2-year follow-up. Mean ages were 41.0 and 47.6 years in the short and the long segment groups, respectively. The 2 groups did not differ significantly in gender, smoking habits, workers' compensation, or litigation (P > 0.05). In the short segment group, postoperative 1-year mean Physical Component Summary (PCS) and Mental Component Summary scores significantly improved (P < 0.001 and P = 0.002, respectively). Domains other than general health perceptions showed significantly improved 1-year follow-up scores (P <or= 0.001). Two-year follow-up scores showed significant improvement (P < 0.001 for physical function [PF], role function as limited by physical problems [RP], bodily pain [BP], social function [SF], and PCS). The vitality (VT) and role function as limited by emotional problems (RE) also improved (P = 0.005 and P < 0.05, respectively). In the long segment group, postoperative 1-year mean PCS scores improved significantly (P < 0.001), with some improvement in Mental Component Summary score (P < 0.05). The long segment group also showed significantly improved PF, RP, BP, and SF scores (P < 0.001). The VT and RE scores gave P = 0.002 and P < 0.05, respectively. Comparing preoperative and 2-year follow-up scores, PCS, PF, RP, BP, and SF showed significant improvement (P < 0.001), and the VT score gave P < 0.01. Mean difference in postoperative and preoperative scores for both groups did not show significant differences (P > 0.05), although the PF score showed differences in 1 and 2-year follow-up scores (P = 0.048 and P = 0.068, respectively). When using strict patient selection criteria that include independent determination of pain generators via pressure-controlled diskography and completion of a preoperative conditioning program for improving general health status, the number of levels in reconstructive lumbar surgery may not significantly impact overall clinical outcome.

Posterior cervical approach for intrathecal baclofen pump insertion in children with previous spinal fusions

Intrathecal baclofen pumps for the management of severe spasticity are being used more often in children with cerebral palsy. The intrathecal catheter is traditionally introduced dorsally in the lumbar region. In some children with previous thoracolumbar fusions for scoliosis, the fusion mass obviates the introduction of the intrathecal catheter. The authors describe their experience with a posterior cervical approach for intrathecal baclofen pump insertion in three patients with spastic quadriplegic cerebral palsy who had previously undergone thoracolumbar fusions for scoliosis. Insertion was successful in all three patients; no complications of catheter disconnection, catheter dislodgment, or cerebrospinal fluid leakage occurred. Follow-up review ranged from 10 to 28 months postoperatively (mean 17 months). The posterior cervical approach for intrathecal baclofen pump insertion is a safe and effective alternative for patients who have previously undergone thoracolumbar spine fusions and in whom the traditional lumbar approach is not feasible.

Conversion of knee fusion to total arthroplasty

Background There are no clear indications for conversion of knee fusion to total arthroplasty. In this paper we report outcome and complications in 8 patients.Patients and methods We reviewed 8 total knee arthroplasties after takedown of previous fusion 24–55 months after the conversion. The original diagnoses were complications following injury in 3 patients, rheumatoid arthritis in 3, complication after chondromalacia in 1 patient and tuberculous arthritis in 1 patient. The age at operation ranged from 31 to 67 years. The time since arthrodesis ranged from 1 to 49 years.Results 5 patients had to undergo reoperation for postoperative complications. 2 patients experienced recurrence of previous deep infection, which led to thigh amputation in one and chronic fistulation in the other. Only 1 patient had an uneventful course after the conversion procedure, but he died later on due to a heart attack. As another patient also died of cardiovascular disease, 5 of the 8 patients were available for evaluation of knee function. In these patients the knee flexion ranged from 90 to 120 degrees, extension lag ranged from 10 to 40 degrees, and all knees were aligned at 6 to 8 degrees of valgus. The Knee Society clinical scores ranged from 47 to 74, the Womac scores ranged from 9 to 47, and EuroQol ranged from 0.1 to 0.8.Interpretation Our findings indicate that conversion of knee arthrodesis to total arthroplasty should only be performed in selected cases, and after giving the patient extensive information about the high risk of rather serious complications.

Cervicothoracic Junction Arthroplasty after Previous Fusion Surgery for Adjacent Segment Degeneration: Case Report

This is the first reported case of cervical arthroplasty using the Bryan Cervical Disc Prosthesis System (Medtronic Sofamor Danek, Inc., Memphis, TN) in the management of adjacent segment degeneration associated with previous fusion surgery and surgery at the cervicothoracic junction. This case report describes a 25-year-old woman who initially underwent a two-level anterior cervical fusion in 1998, 2 years after being involved in a motor vehicle accident. She was well until 18 months before presentation, when she developed bilateral shoulder pain, mechanical neck pain worse on flexion, and bilateral C8 distribution arm pain and paresthesia. On clinical examination, no focal deficits were found, although the range of motion was reduced. Preoperative cervical spine x-rays and magnetic resonance scanning confirmed accelerated degeneration of the C4-C5 and C7-T1 disc spaces, with evidence of neural compression at those levels. After careful consideration of various treatment options and failure of all conservative measures, the patient underwent an anterior C4-C5 and C7-T1 decompression with removal of the anterior cervical plate and placement of two artificial disc prostheses. After surgery, her course was uncomplicated and she was discharged from hospital well. There was complete resolution of the arm symptoms and reduction of the neck pain, with a reduction in the amount of analgesia she was taking. Seven months after surgery, she remains well with repeat x-rays confirming motion at the operated levels. This case demonstrates that cervical arthroplasty is a reasonable treatment option for patients who have had previous surgery in which interbody fusion has been performed and who have developed degeneration of adjacent levels. Despite the altered biomechanics at the cervicothoracic junction, no adverse features were noted with arthroplasty at this level.

Long-term outcome after implantation of the Prestige I disc in an end-stage indication: 4-year results from a pilot study

The long-term function of an artificial cervical disc device is critical to its clinical success. The Prestige I Cervical Disc System has been used clinically since June 1998, and long-term results can now begin to be assessed. The authors conducted clinical and radiographic examinations at 3 and 4 years postoperatively to evaluate the longterm performance of the Prestige I device. A pilot trial was initiated in which the Prestige I disc was implanted in a cohort of patients with end-stage disease, who often had a history of multiple previous fusion procedures. All patients were followed according to a standardized clinical and radiographic protocol until 2 years postoperatively. Outcome measures included the Short Form-36 (SF-36) and Neck Disability Index (NDI) questionnaires, neurological status, and radiographic status. To evaluate the long-term function of the device, Ethics Committee approval was obtained to assess the patients at 3 and 4 years postoperatively. All patients were contacted, and after signing an additional informed consent document, were reevaluated according to the standardized protocol. Of the 17 patients in the original cohort, 13 were evaluated at 3 years and 14 were evaluated at 4 years postoperatively. Clinical outcome measures including the NDI and SF-36 showed good improvement, especially when the endstage nature of the disease is considered. Radiographic analysis showed that the Prestige I disc maintained motion at the treated segment at 3 and 4 years postoperatively. In this report the authors demonstrate the clinical viability of the Prestige I cervical disc system at long-term postoperative intervals, even in the more severe biomechanical environment of end-stage disease.

頚椎前方固定術後に隣接椎間にヘルニアが生じた２例

We successfully treated two patients with cervical disc hernia after anterior fusion. Case 1 was a 50-year-old woman. In 1991 she underwent anterior cervical fusion after being diagnosed with cervical disc hernia (CDH) at another hospital and postoperative course was good. Ten years later, due to numbness of both hands and finger elaborate movement disorder developed, and she visited our hospital for checkup. Cervical disc herinia was noted at the proximal adjacent level of the previous fusion level in magnetic resonance imaging (MRI), for which we performed anterior cervical fusion again. Postoperatively, numbness of the arms and elaborate movement disorder improved. Her Japan Orthopedic Association(JOA) score improved 16 points from 12 points.Case 2 was a 60-year-old man. In 1993 he underwent anterior cervical fusion after being diagnosed with CDH and ossification of the posterior longitudinal ligament. Eight years later, he visited our hospital again for checkup due to numbness of both arms and urine leak. We recognized CDH at the proximal adjacent level of the previous fusion level in MRI for which we performed front fusion again. Postoperatively, spastic paralysis improved. JOA score also improved 12 points from 10 points and he was able to return to work.

Rhabdomyolysis in Lumbar Spine Surgery

The case of a complication sustained by an obese patient undergoing a lumbar spine fusion is reported. To minimize further complications by reporting on this case complicated by rhabdomyolysis in a lumbar fusion, and to include a review of the literature. Rhabdomyolysis has been described as a clinical syndrome initially characterized by darker urine, muscle pain, and weakness from prolonged muscle compression, as in intoxicated patients or after a seizure. Rhabdomyolysis and myoglobinuria have also been reported in the prolonged positions of some surgical procedures. A 40-year-old man developed progressively incapacitating lumbar pain above a previous fusion from L4 to S1, with a severe decline in his functional capacities and a large weight gain. Revision surgery removing the previous instrumentation and performing an instrumented fusion from L2 to L4 was complicated by rhabdomyolysis. After an unremarkable surgery, this patient was hemodynamically unstable when transferred from the operating table to the supine position and required aggressive treatment of severe rhabdomyolysis, which has not previously been reported in this setting. Patients undergoing lumbar spine surgery require decompression of the abdomen, and in this case, a Jackson table was used. Unfortunately, his abdominal girth, even on a Jackson table, was not fully decompressed and resulted in this complication. Further consideration should be given to modifications of positioning for morbidly obese patients.

Mechanical supplementation by non-rigid fixation in degenerative intervertebral lumbar segments: the Wallis system.

A first-generation implant for non-rigid stabilization of lumbar segments was developed in 1986. It included a titanium interspinous blocker and an artificial ligament made of dacron. Following an initial observational study in 1988 and a prospective controlled study from 1988 to 1993, more than 300 patients have been treated for degenerative lesions with this type of implant with clinical and mechanical follow-up. After careful analysis of the points that could be improved, a second-generation implant called the "Wallis" implant, was developed. This interspinous blocker, which was made of metal in the preliminary version, is made of PEEK (polyetheretherketone) in the new model. The overall implant constitutes a "floating" system, with no permanent fixation in the vertebral bone, to avoid the risk of loosening. It achieves an increase in the rigidity of destabilized segments beyond normal values. The clinical trials of the first-generation implant provided evidence that the interspinous system of non-rigid stabilization is efficacious against low-back pain due to degenerative instability and free of serious complications. The first-generation devices achieved marked, significant resolution of residual low-back pain. These results warrant confirmation. A randomized clinical trial and an observational study of the new implant are currently underway. Non-rigid fixation clearly appears to be a useful technique in the management of initial forms of degenerative intervertebral lumbar disc disease. This method should rapidly assume a specific role along with total disc prostheses in the new step-wise surgical strategy to obviate definitive fusion of degenerative intervertebral segments. At present, the Wallis system is recommended for lumbar disc disease in the following indications: (i) discectomy for massive herniated disc leading to substantial loss of disc material, (ii) a second discectomy for recurrence of herniated disc, (iii) discectomy for herniation of a transitional disc with sacralization of L5, (iv) degenerative disc disease at a level adjacent to a previous fusion, and (v) isolated Modic I lesion leading to chronic low-back pain.

Good results of circumferential spine fusion in smokers, using autograft and allograft.

We have examined the rates of anterior interbody fusion of lumbar spine segments following fusion with a fresh frozen femoral head allograft in 25 heavy smoking patients. They were all stabilized both anteriorly and posteriorly. The indications for surgery were: degenerative disc disease, degenerative spondylolisthesis and nonunion following previous posterolateral fusion of lumbar spine segments. Only patients who had fusion of one or two lumbar segments were included. They all were stabilized posteriorly with pedicle screws and autogenic iliac bone graft. The fusion was assessed at least one year after surgery according to plan X-rays as "Solid", "Questionable" or "Failure". One patient was found at follow up not fused, in another one the fusion was "questionable" and all the other 23 patients had an anterior solid fusion. Clinically, 84% of the patients had the same or improved work status as before surgery and 68% acknowledged that they were satisfied with the surgical results. No major complications were recorded and the average length of hospitalization was 10.3 days.

Progesterone-induced increase of sperm cytosolic calcium is enhanced by previous fusion of spermatozoa to prostasomes

Ejaculated spermatozoa must undergo a number of modifications before becoming able to fertilize the oocyte. The interaction of sperm with other semen components may influence these phenomena; human semen contains vesicles of prostatic origin, called pro stasomes that may fuse to sperm at slightly acidic to neutral pH values.Prostasomes contain calcium and it has been demonstrated that their fusion with spermatozoa produces a transient increase (wave) of [Ca2+]iin these cells. The fusion process also transfers protein and lipid to spermatozoa. These phenomena may induce long-lasting changes of sperm properties.We test the hypothesis that spermatozoa, as modified by fusion, change their ability to undergo the progesterone-induced increase of [Ca2+]iand we find that the increase of [Ca2+]iproduced by the fusion with prostasomes and by the stimulation with progesterone are independent and additive phenomena. We also find that spermatozoa present a stronger response to the progesterone-induced increase of [Ca2+]iif they are previously made to fuse with prostasomes. This effect does not depend directly on the [Ca2+]iincrease due to fusion, since it is still present after the [Ca2+]ihas returned to resting values.

Circular permutation and receptor insertion within green fluorescent proteins.

Many areas of biology and biotechnology have been revolutionized by the ability to label proteins genetically by fusion to the Aequorea green fluorescent protein (GFP). In previous fusions, the GFP has been treated as an indivisible entity, usually appended to the amino or carboxyl terminus of the host protein, occasionally inserted within the host sequence. The tightly interwoven, three-dimensional structure and intricate posttranslational self-modification required for chromophore formation would suggest that major rearrangements or insertions within GFP would prevent fluorescence. However, we now show that several rearrangements of GFPs, in which the amino and carboxyl portions are interchanged and rejoined with a short spacer connecting the original termini, still become fluorescent. These circular permutations have altered pKa values and orientations of the chromophore with respect to a fusion partner. Furthermore, certain locations within GFP tolerate insertion of entire proteins, and conformational changes in the insert can have profound effects on the fluorescence. For example, insertions of calmodulin or a zinc finger domain in place of Tyr-145 of a yellow mutant (enhanced yellow fluorescent protein) of GFP result in indicator proteins whose fluorescence can be enhanced severalfold upon metal binding. The calmodulin graft into enhanced yellow fluorescent protein can monitor cytosolic Ca(2+) in single mammalian cells. The tolerance of GFPs for circular permutations and insertions shows the folding process is surprisingly robust and offers a new strategy for creating genetically encodable, physiological indicators.

Cause of adjacent-segment disease after spinal fusion

For about 40 years cervical decompression and fusion has been effective treatment for myelopathy or radiculopathy attributable to a degenerated, herniated, or unstable intervertebral disc. 1 Lunsford LD Bissonette DJ Jannetta PJ Sheptak PE Zorub DS Anterior surgery for cervical disc disease-part 1: treatment of lateral cervical disc herniation in 253 cases.. J Neurosurg. 1980; 53: 1-11 Crossref PubMed Scopus (277) Google Scholar , 2 Robinson RA Smith GW Anterolateral cervical disc removal and interbody fusion for cervical disc syndrome.. Bull Johns Hopkins Hosp. 1955; 96: 223-224 Google Scholar Radiographic and clinical studies have shown that in time the disc adjacent to the fused spinal segment occasionally degenerates or becomes unstable. 1 Lunsford LD Bissonette DJ Jannetta PJ Sheptak PE Zorub DS Anterior surgery for cervical disc disease-part 1: treatment of lateral cervical disc herniation in 253 cases.. J Neurosurg. 1980; 53: 1-11 Crossref PubMed Scopus (277) Google Scholar , 3 Wu W Thuomas K-Å Hedlund R Leszniewski W Vavruch L Degenerative changes following anterior cervical discectomy and fusion evaluated by fast spin-echo MR imaging.. Acta Radiol (Copenhagen). 1996; 37: 614-617 Crossref PubMed Scopus (46) Google Scholar , 4 Aota Y Kumano K Hirabayashi S Postfusion instability at the adjacent segments after rigid pedicle screw fixation for degenerative lumbar spinal disorders.. J Spinal Disord. 1995; 8: 464-473 Crossref PubMed Google Scholar , 5 Hilibrand AS Yoo JU Carlson GD Bohlman HH The success of anterior cervical arthrodesis adjacent to a previous fusion.. Spine. 1997; 22: 1574-1579 Crossref PubMed Scopus (147) Google Scholar , 6 Etebar S Cahill DW Risk factors for adjacent-segment failure following lumbar fixation with rigid instrumentation for degenerative instability.. J Neurosurg. 1999; 90: 163-169 Crossref PubMed Scopus (340) Google Scholar This adjacent-segment disease has generated considerable interest, and a new implant—the artificial disc—is being developed in response to concerns about this disorder.

Inside-outside technique for posterior occipitocervical spine instrumentation and stabilization: preliminary results.

The authors present a series of 16 patients who underwent inside-outside occipital and posterior cervical spine stabilization. In this technique, the screw was placed from the inside of the occiput to the outside. An articular (lateral) mass plate was contoured to the shape of the occipital bone and the cervical spine and affixed to the occiput with a flat-headed screw or stud placed through a burr hole in the calvaria with the flat head of the screw in the epidural space and the threads facing outward. The bone plate was then secured with a nut to the occipital screw and the cervical plate was attached to the spine with a bone screw that coursed through the plate and into the articular pillar. Our series included six children and 10 adults. In five patients, previous fusion had failed; in two patients spinal instability was secondary to Down's syndrome; two patients' instability was related to developmental anomalies; and in five patients spinal instability was due to the presence of tumor. One patient with rheumatoid arthritis had undergone a transoral procedure. Two patients had suffered traumatic fracture. Three patients died of causes unrelated to the procedure, one patient died of metastatic cancer, and one patient died in a long term care facility of cardiopulmonary complications. One patient with renal failure suffered a hemorrhage from an arteriovenous fistula after being treated with dialysis. In one child, a nut backed off after 3 months. The nut was reseated, and a maturing arthrodesis was present. The authors conclude that the inside-outside occipitocervical fixation is an effective technique for stabilizing the cervical spine.

Management of flatback and related kyphotic decompensation syndromes.

The authors, in this retrospective study, examined a group of patients with flatback syndrome and a related kyphotic decompensation syndrome. Results of nonrealignment treatment as well as revision surgery with sagittal realignment were reviewed. To determine effectiveness of physical therapy and limited surgical (instrumentation removal) as well as major realignment surgical treatment in the sagittally malaligned spine. Flatback is a sagittal plane deformity associated with distraction instrumentation for scoliosis correction. Kyphotic decompensation syndrome involves malaligned fusions from the sacrum for disease other than scoliosis. Several studies describe surgical realignment for flatback involving instrumentation systems no longer commonly applied. Guidelines for a systematic approach to flatback and kyphotic decompensation syndromes are lacking. Forty-eight patients with flatback and kyphotic decompensation syndromes were reviewed. Treatment groups were defined by treatment approach and level of previous fusion. Effectiveness of treatment was reviewed in terms of radiographic sagittal alignment and self-reported pain. Twenty patients were treated without realignment revision surgery. Twenty-eight patients were treated with anterior and posterior osteotomies and realignment with instrumentation. For patients originally fused to the sacrum, realignment averaged 12 cm. Pain was reduced from 7 to 3 (10-point scale). In patients fused to L4 or L5, realignment averaged 7 cm. Pain was reduced from 6 to 2. Magnetic resonance imaging revealed viable caudal discs in four patients who were consequently spared extension of fusion to the sacrum. Treatment without realignment surgery demonstrated long-term success in 27% of cases. The latter all had two intact discs below the previous fusion and sagittal malalignment less than 4 cm. Realignment surgery effectively reduced pain in patients failing a conservative approach.

The success of anterior cervical arthrodesis adjacent to a previous fusion.

A retrospective review of all patients surgically treated for adjacent segment disease of the cervical spine over a 20-year period. To determine the clinical and radiographic success of discectomy with interbody grafting and corpectomy with strut grafting in the treatment of adjacent segment disease of the cervical spine. Up to 25% of all patients undergoing anterior cervical fusion have new disease due to degeneration of an adjacent segment within 10 years. The success of surgical treatment in these patients with adjacent segment disease has not been reported. Thirty-eight patients were surgically treated for adjacent segment disease by discectomy with interbody grafting or corpectomy with strut grafting. Arthrodesis was evaluated by flexion-extension lateral radiographs and clinical outcomes were assessed using Robinson's criteria at least 2 years after surgery. Fusion rates were compared by Fisher's exact test, and outcomes were compared by rank-sum analysis. The rate of arthrodesis was significantly lower in the 24 patients treated by discectomy with interbody grafting at one or more levels (63%) than in the 14 patients treated by corpectomy with strut grafting (100%; P = 0.01). Clinical outcomes were similar for the corpectomy and discectomy groups (P = 0.55). There was a trend toward better outcomes in patients who achieved a solid arthrodesis (P = 0.13). Achieving fusion is more difficult when anterior cervical arthrodesis is performed adjacent to a prior fusion. Strut grafting resulted in a significantly higher rate of arthrodesis than interbody grafting.

Construction of CTB fusion proteins for screening of monoclonal antibodies against Salmonella typhi OmpC peptide loops.

Mice were immunized with resin-bound peptides whose sequences have been proposed to be part of exposed loops in Salmonella typhi outer membrane protein OmpC. To screen hybridomas for monoclonal antibodies against those epitopes, we designed fusion proteins where the candidate peptide sequence was attached to the amino end of cholera toxin B-subunit (CTB). The constructed fusion proteins allowed the efficient selection of positive clones by GM1-ELISA. Selected antibodies recognized purified OmpC and whole Salmonella bacteria. This suggests a native structure of our genetically attached peptides in agreement with immunological properties reported for previous CTB recombinant fusion proteins. In a more general context, CTB hybrids could be used to screen for antibodies towards immunogenic epitopes in other systems. This might turn out to be particularly useful when producing antibodies against peptide sequences in microorganisms whose handling is difficult or that pose inherent health risks.

Perceptual-based hyperspectral image fusion using multiresolution analysis

A perceptual-based multiresolution image fusion technique is demonstrated using the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) hyperspectral sensor data. The AVIRIS sensor, which simultaneously collects information in 224 spectral bands that range from 0.4 to 2.5 μm in approximately 10-nm increments, produces 224 images, each representing a single spectral band. The fusion algorithm consists of three stages. First, a Daubechies orthogonal wavelet basis set is used to perform a multiresolution decomposition of each spectral image. Next, the coefficients from each image are combined using a perceptual-based weighting. The weighting of each coefficient, from a given spectral band image, is determined by the spatial-frequency response (contrast sensitivity) of the human visual system. The spectral image with the higher saliency value, where saliency is based on a perceptual energy, will receive the larger weight. Finally, the fused coefficients are used for reconstruction to obtain the fused image. The image fusion algorithm is analyzed using test images with known image characteristics and image data from the AVIRIS hyperspectral sensor. By analyzing the signal-to-noise ratios and visual aesthetics of the fused images, contrast-sensitivity-based fusion is shown to provide excellent fusion results and to outperform previous fusion methods.

The Effect of Craniovertebral Fusion on Occlusion

The purpose of this study was to compare the effect of head posture on occlusion in subjects with craniovertebral fusion to that in normal unfused subjects. The experimental group consisted of five subjects (age range 30-76) who have all undergone previous surgical fusion of the craniovertebral region. The control group consisted of five unfused subjects matched by age, race and gender. Each subject's tooth contacts were recorded with a computerized dental instrument known as the T-scan. The tooth contacts were measured several times for each subject with the head tilted backwards (45 degrees) and forwards (30 degrees). A modification of Wilcoxon's rank sum test was used to compare the location of the tooth contacts and compare any variations between the craniovertebral-fused subjects' occlusal contact patterns and those of the normal nonfused patients. The results indicated that four of the five fused subjects had occlusal contact patterns that differed from their matched counterparts, thus suggesting that fusion of the craniovertebral region interferes with a normal mechanism that permits changes in head posture to shift tooth contact points. These results suggest that those who manage problems related to occlusion (craniofacial pain syndromes) need to consider the influence of the craniovertebral region on both occlusion and jaw position.

Genetic analysis of membrane protein topology by a sandwich gene fusion approach.

We describe a cloning vector that allows the construction of phoA sandwich fusions in which mature alkaline phosphatase is inserted into target proteins. In contrast to previous fusions obtained using the TnphoA transposon, the entire amino acid sequence of the target protein is present in the fusion product. We have constructed a series of sandwich fusions of alkaline phosphatase to the multispanning cytoplasmic membrane protein MalF. Despite the fact that the alkaline phosphatase was tethered to MalF at both its N and its C terminus, the enzyme exhibited high activity when it was fused to a periplasmic domain of the membrane protein. Cells harboring an alkaline phosphatase sandwich fusion to the end of the first membrane-spanning segment of MalF exhibited both MalF and alkaline phosphatase activity. When alkaline phosphatase was inserted into a cytoplasmic domain of MalF, its specific activity was very low. Our results suggest that the alkaline phosphatase activity of phoA sandwich fusions provides a more sensitive monitor than previous methods of the cellular localization of the domain of the target protein to which the enzyme is fused. Thus, the sandwich fusion approach can give a more accurate picture of membrane protein topology.

Production of Escherichia coli-specific hybridomas by using gnotobiotic mice

Monoclonal antibodies provide a rapid and specific means of direct detection of microorganisms in water and food samples. However, monoclonal antibodies specific for some bacteria are difficult to obtain; a good example of such a bacterium is Escherichia coli. Gnotobiotic BALB/c mice immunized with whole-cell preparations of heat-treated strains of E. coli and subjected to high-frequency antigen injection showed a significant increase in the number of specific hybridomas produced. Fusions obtained by using regular BALB/c mice immunized by using standard immunization protocols produced nonspecific hybridomas. Twenty-one stable hybridomas that did not cross-react with Klebsiella pneumoniae ATCC 13883 or Citrobacter freundii 1604770 were obtained from gnotobiotic mice. The bacterial strains were selected for the specificity tests because of their high cross-reactivity, which has been detected in previous fusion experiments. The method of immunization described here offers the potential of improving the production of highly specific hybridomas for bacteria which have been difficult to obtain.