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ABSTRACT: A microfluidic device to quantify bacterial chemotaxis has been proposed, which generates a linear concentration gradient of chemoattractant in the main channel only by convective and molecular diffusion, and which enables the bacteria to enter the main channel in a single file by hydrodynamic focusing technique. The trajectory of each bacterium in response to the concentration gradient of chemoattractant is photographed by a CCD camera and its velocity is acquired by a simple PTV (Particle Tracking Velocimetry) algorithm. An advantage of this assay is to measure the velocity of a single bacterium and to quantify the degree of chemotaxis by analyzing the frequency of velocities concurrently. Thus, the parameter characterizing the motility of wild-type Escherichia coli strain RP437 in response to various concentration gradients of L-aspartate is obtained in such a manner that the degree of bacterial chemotaxis is quantified on the basis of a newly proposed Migration Index.
Biomedical Microdevices 07/2009; 11(5):1135-43. · 3.03 Impact Factor
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ABSTRACT: Prospective, randomized, double-blind study.
To evaluate intravenous corticosteroids in preventing delayed extubation after multilevel corpectomy and strut graft reconstructive procedures and to identify risk factors for delayed extubation in these patients.
We performed a prospective, randomized double-blind study in patients undergoing multilevel cervical corpectomy procedures. Our hypothesis was that high-dose perioperative steroids would decrease edema and thus decrease the incidence of delayed extubation.
We studied patients undergoing 2- or 3-level anterior cervical corpectomy procedures with anterior strut graft reconstruction. Sixty-six patients were randomized to receive 3 doses of either intravenous dexamethasone (n = 35) or saline (n = 31). The first dose was given before the incision, with subsequent doses given 8 and 16 hours later. Patients remained intubated until postoperative day 1, at which time a cuff leak test was performed by the anesthesiology attending. If a leak was present, the patient was extubated. If not, the test was repeated each postoperative day until a leak was present, indicating a patent airway.
Five of 35 (14%) in the steroid group and 6 of 31 (19%) in the saline group required delayed extubation (P = 0.22). There were no statistical differences in preoperative parameters of age, gender, diagnosis, smoking history, BMI, number of operative levels, or preoperative American Society of Anesthesiologists rating between the 2 groups. Similarly there were no differences between the groups for duration of anesthesia, intraoperative colloids or crystalloids, intraoperative blood loss, or intraoperative urine output. The data for both groups were pooled to evaluate risk factors for delayed extubation. The only statistically significant risk factor for delayed extubation in this study was female gender (P = 0.0001).
Based on our data, we cannot recommend intravenous dexamethasone for prevention of delayed extubation after multilevel anterior cervical corpectomy and strut grafting procedures.
Spine 02/2009; 34(3):229-32. · 2.08 Impact Factor
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ABSTRACT: Abstract
Background
Treatment of unstable thoracolumbar fractures is controversial regarding short or long segment pedicle screw fixation. Although long level fixation is better, it can decrease one motion segment distally, thus increasing load to lower discs.
Methods
We retrospectively analyzed 31 unstable thoracolumbar fractures with partial or intact neurology. All patients were operated with posterior approach using pedicle screws fixed two levels above and one level below the fracture vertebra. No laminectomy, discectomy or decompression procedure was done. Posterior fusion was achieved in all. Post operative and at final follow-up radiological evaluation was done by measuring the correction and maintenance of kyphotic angle at thoracolumbar junction. Complications were also reported including implant failure.
Results
Average follow-up was 34 months. All patients had full recovery at final follow-up. Average kyphosis was improved from 26.7° to 4.1° postoperatively and to 6.3° at final follow-up. And mean pain scale was improved from 7.5 to 3.9 postoperatively and to 1.6 at final follow-up, All patients resumed their activity within six months. Only 4 (12%) complications were noted including only one hardware failure.
Conclusion
Two levels above and one level below pedicle screw fixation in unstable thoracolumbar burst fracture is useful to prevent progressive kyphosis and preserves one motion segment distally.
Journal of Orthopaedic Surgery and Research. 01/2009;
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Peter Angele,
Rainer Müller,
Detlef Schumann,
Carsten Englert,
Johannes Zellner,
Brian Johnstone, Jung Yoo,
Joachim Hammer,
Johann Fierlbeck,
Martin K Angele,
Michael Nerlich,
Richard Kujat
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ABSTRACT: Composite scaffolds of homogeneously mixed esterified hyaluronan (HY) and gelatin (G) were manufactured with variable component compositions (HY100%; HY95%/G5%; HY70%/G30%). The goals of this study were to analyze the produced composite scaffolds using physical and chemical methods, for example, scanning electron microscopy, IR-spectroscopy, water contact angle, protein assay, and tensile testing as well as to assess the effects of adding gelatin to the composite scaffolds on attachment, proliferation, and chondrogenic differentiation of human mesenchymal stem cells. Numbers of attached cells were significantly higher on the composite material compared to pure hyaluronan at different time points of two-dimensional or three-dimensional cell culture (p< 0.02). In composite scaffolds, a significantly greater amount of cartilage-specific extracellular matrix components was deposited after 28 days in culture (glycosaminoglycan: p < 0.001; collagen: p < 0.001) as compared with 100% hyaluronan scaffolds. Additionally, gelatin-containing composite scaffolds displayed stronger promotion of collagen type II expression than pure hyaluronan scaffolds. The mechanism, based on which gelatin influences cell adhesion, was examined. The effect was inhibited by collagenase treatment of the composites or by addition of alpha5beta1-integrin blocking antibodies to the cell suspension. In summary, the results describe the establishment of a class of composite polymer scaffolds, consisting of esterified hyaluronan and gelatin, which are potentially useful for cell-based tissue engineering approaches using mesenchymal stem cells for chondrogenic differentiation.
Journal of Biomedical Materials Research Part A 12/2008; 91(2):416-27. · 2.63 Impact Factor
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ABSTRACT: This prospective, randomised case-control study was made to determine effectiveness of low-dose Depo-Medrol applied to the affected nerve root after discectomy. Fifty seven patients with L4-5 or L5-S1 single level disc herniation with unilateral leg pain were selected for the study and were divided in two groups. Twenty eight patients were in the control group and 29 in the steroid group. Discectomy was done after flavotomy in all patients. In the steroid group low-dose 40 mg Depo-Medrol soaked Gelfoam was applied over the affected nerve root after discectomy while in the control group neither saline nor plain Gelfoam was applied to affected root. Postoperatively, patients were asked to evaluate backache using VAS which was compared statistically using the unpaired t test. Statistical difference was significant (p < 0.0001) regarding postoperative VAS during the first month and then it became insignificant. Results show that local application of low-dose Depo-Medrol is helpful in reducing immediate postoperative backache after discectomy, but it is not effective in the long-term.
International Orthopaedics 05/2008; 33(3):737-43. · 2.03 Impact Factor
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ABSTRACT: Defects of the meniscus greatly alter knee function and predispose the joint to degenerative changes. The purpose of this study was to test a recently developed cell-scaffold combination for the repair of a critical-size defect of the rabbit medial meniscus. A bilateral, complete resection of the pars intermedia of the medial meniscus was performed in 18 New Zealand White rabbits. A hyaluronan/gelatin composite scaffold was implanted into the defect of one knee of 6 rabbits and the contralateral defect was left untreated. Scaffolds loaded with autologous marrow-derived mesenchymal stem cells and cultured in a chondrogenic medium for 14 days were implanted in a second series of 12 rabbits. Empty scaffolds were implanted in the contralateral knees. Meniscii were harvested at 12 weeks. Untreated defects had a muted fibrous healing response. Defects treated with cell-free implants showed also predominantly fibrous tissue whereas fibrocartilage was present in some scaffolds. The cross-sectional width of the repair tissue after treatment with cell-free scaffolds was significantly greater than controls (p < 0.05). Pre-cultured implants integrated with the host tissue and 8 of 11 contained meniscus-like fibrocartilage, compared with 2 of 11 controls (p < 0.03). The mean cross-sectional width of the pre-cultured implant repair tissue was greater than controls (p < 0.004). This study demonstrates the repair of a critical size meniscal defect with a stem cell and scaffold based tissue engineering approach.
Journal of Biomedical Materials Research Part A 05/2008; 85(2):445-55. · 2.63 Impact Factor
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ABSTRACT: Retrospective review.
To quantify and describe perioperative complication rates in a large series of well-matched elderly patients who underwent lumbar decompression and arthrodesis.
Posterior lumbar decompression and fusion is frequently performed to treat lumbar stenosis with instability. An increasing number of elderly patients are undergoing operative treatment for degenerative lumbar disease. The reported morbidity of performing decompression and arthrodesis in this population varies widely in the literature, with recent reports showing a high rate of major complications.
A total of 166 patients age 65 or older that underwent primary posterior lumbar decompression and fusion with (group 1; n = 75) or without (group 2; n = 91) instrumentation were included. Hospital records were reviewed for the occurrence of any complications (major and minor), the need for transfusion, estimated length of stay, and disposition at discharge. Logistic regression (with the presence/absence of major complications as the dependent variable) was used to identify risk factors for the occurrence of a complication.
Five major complications (3%) occurred (group 1, 1; group 2, 4). Minor complications developed in 30.7% of group 1 and 31.9% of group 2. There were no deaths, and only one perioperative complication was attributable to the use of instrumentation. Decompression/fusion of 4 or more segments was significantly associated with the occurrence of a major complication. Advanced age, the presence of medical comorbidities, or the use of instrumentation did not increase the rate of major or minor complications. The occurrence of either a major or minor complication prolonged hospital stay.
Posterior lumbar decompression and fusion can be safely performed in elderly patients, with a low rate of major complications. The addition of instrumentation does not increase the complication rate. These results differ from those previously reported in the literature, which describe a significantly higher rate of complications in this age group, with a prolonged rate of hospitalization.
Spine 02/2007; 32(2):230-5. · 2.08 Impact Factor
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ABSTRACT: Case report.
To report the occurrence of the rare complication of fibular strut graft fractures in 2 patients.
Fatigue fracture of fibular strut allograft following anterior cervical corpectomy and fusion has rarely been reported.
Two patients sustained delayed fractures of their anterior fibular strut allografts following combined three-level cervical corpectomy and posterior instrumented fusion at 9 and 17 months after surgery. Both patients had successfully fused both ends of their anterior strut grafts.
Both patients were successfully treated by revision posterior instrumented fusion without revision of the anterior strut. These patients' allografts were harvested from the same donor, a 69-year-old woman. The tissue bank involved does not use donor age or osteoporosis as exclusion criteria for structural allograft donation.
The fact that this relatively rare complication occurred in 2 patients who shared the same donor suggests that the mechanical strength of the donor allograft may have played a significant role in both fractures.
Spine 09/2006; 31(17):E595-9. · 2.08 Impact Factor
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02/2006: pages 83 - 111; , ISBN: 9780471741817
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ABSTRACT: To compare the incidence, prevalence, and rate of improvement of dysphagia in patients undergoing anterior cervical spine surgery with two different anterior instrumentation designs.
The study subjects were 156 consecutive patients undergoing anterior cervical spine surgery with plate fixation. We compared the incidence of dysphagia among the two different plate groups both produced by the same manufacturer (Medtronic Danek); the Atlantis plate has thicker and wider plate dimensions than the Zephir plate. Dysphagia evaluations were performed prospectively by telephone interviews at 1, 2, 6, 12, and 24 months following the procedure. Risk factors such as gender, revision surgery, and number of surgical levels were compared between the groups and were not statistically different.
Overall incidences of dysphagia were 49%, 37%, 20%, 15.4%, and 11% at 1, 2, 6, 12, and 24 months, respectively. Severe and disabling dysphagia is reported to be a relatively uncommon complication of anterior cervical surgery. However, a significant number of patients report mild to moderate discomfort including double-swallowing and catching sensation. Except at the 2-month follow-up point, the Atlantis plate group had higher incidences of dysphagia than the Zephir group at all time points (57% vs 50%, 36% vs 4%, 23% vs 14%, 17% vs 7%, 14% vs 0% at 1, 2, 6, 12, and 24 months, respectively). The Atlantis plate group had a 14% incidence of dysphagia at 2 years compared with the Zephir group, which had a 0% incidence at 2 years (P < 0.04). For primary surgeries, there was a higher incidence of dysphagia at all time points in the Atlantis group when compared with the Zephir group (58% vs 43%, 35% vs 30%, 22% vs 10%, 17% vs 0%, and 13% vs 0% at 1, 2, 6, 12, and 24 months, respectively) (P < 0.04 at 1 year). A regression analysis was performed. The resulting formulas predict the permanent rate of dysphagia for the Atlantis group is 13.6% and for the Zephir group is 3.58%.
The use of a smaller and smoother profile plate such as the Zephir does reduce the incidence of dysphagia as compared with a slightly larger and less smooth plate such as the Atlantis.
Journal of Spinal Disorders & Techniques 10/2005; 18(5):406-9. · 1.50 Impact Factor
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ABSTRACT: Primary monolayer cultures of marrow stromal cells, as they are referred to in the hemopoietic field, contain monocytes, macrophages,
and endothelial cells (1,2). In addition, they contain precursor cells that can differentiate into multiple mesenchymal cell types (3–5). In vitro, the highly proliferative adherent fibroblast-like cells of marrow form colonies, which Friedenstein termed colony-forming
units-fibroblast (CFU-f) (3). These cells are cultured as stromal support cells for hematopoietic cell differentiation, but the use of these cells for
the investigation of mesenchymal tissue cell differentiation has become common. In recent years, there has been interest in
using these cells for regeneration/repair of mesenchymal tissues (6,7).
12/1999: pages 313-315;
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ABSTRACT: Severe and disabling dysphagia is a relatively uncommon complication of anterior cervical spine surgery. However, the incidence of dysphagia ranges widely (2% to 60%). Furthermore, risk factors that contribute to the development of dysphagia have not been well identified.
The purpose of this study was to evaluate the prevalence of dysphagia after anterior cervical spine surgery, and to identify any risk factors associated with increased dysphagia.
This study is a prospective cohort study designed to evaluate the prevalence of dysphagia at 1, 2, 6, 12, and 24 months. Patients were prospectively interviewed at 1, 2, 6, 12, and 24 months regarding the presence and subjective severity of dysphagia.
Between the period of 1999 and 2002, 348 cervical spine surgeries were performed using the anterior Smith Robinson approach. 310 of these patients were available for 2-year follow-up. OUTCOMES MEASURE: Using the dysphagia grading system defined by Bazaz et al. (Spine 2002), we prospectively evaluated patients' postoperative dysphagia.
The presence and severity of dysphagia were reported during the telephone interviews performed at 1, 2, 6, 12, and 24 months after the procedure. Proportion analysis (chi-square or a Fisher Exact Test), prevalence ratios, and 95% confidence intervals were used to compare the prevalence of dysphagia with age, gender, type of surgery (eg, discectomy vs. corpectomy, primary vs. revision), use of instrumentation, number and location of surgical levels.
The overall prevalences for dysphagia at 1, 2, 6, 12, and 24 months were 54.0%, 33.6%, 18.6%, 15.2%, and 13.6%. The prevalence of dysphagia was found to be significantly higher in women (18.3%) than men (9.9%) 2 years after the surgery. Revision surgery patients (27.7%) also had a significantly higher prevalence of dysphagia than primary surgery (11.3%) patients 2 years after the surgery. Patients who underwent more than two-level surgery (19.3%) also had significantly higher rates of dysphagia 2 years after their procedures than patients who had two or less levels (9.7%) operated on.
Overall the incidence of dysphagia 2 years after anterior cervical spine surgery was 13.6%. Risk factors for long-term dysphagia after anterior cervical spine surgery include gender, revision surgeries, and multilevel surgeries. The use of instrumentation, higher levels, or corpectomy versus discectomy did not significantly increase the prevalence of dysphagia.
The Spine Journal 7(2):141-7. · 3.29 Impact Factor
