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Biomedical subjects

S S Hu

Publications and source records attributed to S S Hu.

At least 19 recordsLinked to original sources
PubMed2006

[Research on development of gold immunochromagraphic assay test kit for serum Coxsackievirus IgM antibody.].

BACKGROUND: To develop gold immunochromatographic assay (GICA) test kit for serum Coxsackievirus IgM antibody and optimize the key experiment conditions. METHODS: Colloidal gold particles of 20 nm were prepared and coupled with sheep anti-human IgM, the gold immunochromatography assay test kit was setup for serum Coxsackievirus IgM antibody. RESULTS: The spheroidal colloid gold particles of 20 nm showed bright red in color. The minimal stable concentration (MSC) of gold sheep anti-human IgM was 1 ug/ml, and the suitable stable concentration (SSC) was 1.5 ug/ml. The pH 8.2 was appropriate; 30 sera samples were tested by GICA and ELISA, there was no significant difference between the two methods. CONCLUSION: The quality of gold immunochromatography assay test kit is associated with such factors as the quality and quantity of antigen or antibody, colloid gold particles, buffers, etc.

Chromatography, Affinity↗
PubMed2001

Magnetic resonance imaging measurement of relaxation and water diffusion in the human lumbar intervertebral disc under compression in vitro.

STUDY DESIGN: Twelve lumbar intervertebral disc specimens were imaged with magnetic resonance imaging to estimate relaxation constants, T1 and T2, and tissue water diffusion, before and after applying compression. OBJECTIVES: The objectives of the study were to measure T1, T2, and water diffusion for differences with loading state, region of the disc (anulus fibrosus or nucleus pulposus), and grade of degeneration. SUMMARY OF BACKGROUND DATA: Magnetic resonance imaging can be used qualitatively to estimate water content and degeneration of the intervertebral disc. Beyond structural information of images, the relaxation times T1 and T2 may contain information on the changes occurring with degeneration. A modified spin-echo sequence can be used to estimate tissue water diffusion in cartilage and disc specimens with the ability to measure anisotropy. METHODS: Specimens were imaged in a 1.5-Tesla clinical scanner. T1, T2, and water diffusion were estimated from midsagittal images. Magnetic resonance imaging parameters were calculated before and after axial loading. The measured T1, T2, and D (diffusion coefficient) were compared before and after compression, and for the diffusion data, also by direction to consider anisotropy. RESULTS: For the T1 data, a significant difference was found by region, nucleus > anulus, and loading state, loaded > unloaded. For the T2 values, there was a significant difference by region, nucleus > anulus, and Thompson grade. For diffusion, significant differences were found by region, nucleus > anulus, Thompson grade, direction of diffusion, and state of compression, loaded > unloaded. CONCLUSIONS: This study demonstrated that magnetic resonance imaging can be used to measure significant changes in T1, T2, or diffusion in intervertebral disc specimens by region, loading condition, or Thompson grade.

Adolescent↗
PubMed2001

Management of fixed sagittal plane deformity: results of the transpedicular wedge resection osteotomy.

STUDY DESIGN: Retrospective review of a consecutive clinical series. OBJECTIVES: To evaluate the efficacy of the transpedicular wedge resection osteotomy as a technique for correction of sagittal and coronal deformity and to assess the clinical value of the procedure as assessed by patient satisfaction. SUMMARY OF BACKGROUND DATA: The transpedicular wedge resection osteotomy is a well-established procedure for management of fixed sagittal deformity in ankylosing spondylitis. The utility of the procedure for applications in fixed deformity other than ankylosing spondylitis has not been demonstrated, and the efficacy of the procedure in the correction of coronal deformity has not been reported. METHODS: A total of 13 consecutive cases undergoing transpedicular wedge resection osteotomy for the management of sagittal deformity of any etiology were reviewed. Radiographic studies, complications, and satisfaction assessment using the modified Scoliosis Research Society instrument were the outcome parameters measured. RESULTS: Etiologies of deformity included postsurgical, ankylosing spondylitis, idiopathic, and infectious. Measurement of C7 sagittal plumb line to sacrum improved 63% at the most recent follow-up. Lumbar lordosis increased from -15.5 degrees to -45.4 degrees. Coronal balance was improved in all patients who had preoperative imbalance, with an average improvement of 60% maintained at follow-up. Patient satisfaction was high in all patients and not dependent on the etiology of deformity. CONCLUSIONS: The transpedicular wedge resection osteotomy is an effective procedure for the management of fixed sagittal deformity and is generalizable for multiple etiologies. Simultaneous correction of coronal deformity is possible. The clinical value of the procedure is demonstrated in high rates of patient satisfaction.

Adult↗
PubMed2001

Parametric finite element analysis of vertebral bodies affected by tumors.

The vertebral column is the most frequent site of metastatic involvement of the skeleton. Due to the proximity to the spinal cord, from 5% to 10% of all cancer patients develop neurologic manifestations. As a consequence, fracture risk prediction has significant clinical importance. In this study, we model the metastatically involved vertebra so as to parametrically investigate the effects of tumor size, material properties and compressive loading rate on vertebral strength. A two-dimensional axisymmetric finite element model of a spinal motion segment consisting of the first lumbar vertebral body (no posterior elements) and adjacent intervertebral disc was developed to allow the inclusion of a centrally located tumor in the vertebral body. After evaluating elastic, mixed, and poroelastic formulations, we concluded that the poroelastic representation was most suitable for modeling the metastatically involved vertebra's response to compressive load. Maximum principal strains were used to localize regions of potential vertebral trabecular bone failure. Radial and axial vertebral body displacements were used as relative indicators of spinal canal encroachment and endplate failure. Increased tumor size and loading rate, and reduced trabecular bone density all elevated axial and radial displacements and maximum tensile strains. The results of this parametric study suggest that vertebral tumor size and bone density contribute significantly to a patients risk for vertebral fracture and should be incorporated in clinical assessment paradigms.

Biomechanical Phenomena↗
PubMed2001

Anterior and posterior allografts in symptomatic thoracolumbar deformity.

The radiographic and clinical results of 105 patients with symptomatic spinal deformities were categorized retrospectively based on surgical approach and type of bone autograft or allograft used for each patient's fusion surgery into seven different groups and compared with one another. The three bone autograft control groups were posterior autograft only (n = 20), anterior autograft only (n = 6), and combined anterior and posterior autograft (n = 12). The allograft groups were posterior morcellized allograft (n = 7), posterior morcellized allograft and anterior autograft (n = 11), anterior structural interbody allografts and posterior mixture of allograft and autograft (n = 37), and anterior strut allograft with posterior mixture of allograft and autograft (n = 12). Radiographs revealed high pseudoarthrosis rates for adults with a posterior-only allograft and with anterior strut allografts spanning four or more levels. Results of the self-assessment outcomes questionnaire, at a mean follow-up period of 52 months, revealed less pain and improved cosmesis for all groups, and improved function in patients who had undergone combined anteroposterior fusion. The authors conclude that posterior cancellous allograft is a poor substitute for autograft bone and that strut allografts spanning more than four levels require technique modifications to enhance their effectiveness. In general, anterior structural allografts are effective in maintaining correction, result in fusion rates comparable to those of autografts, and correlate to improved outcomes.

Adolescent↗
PubMed2001

Excision of hemivertebrae in the management of congenital scoliosis involving the thoracic and thoracolumbar spine.

We present a study of ten consecutive patients who underwent excision of thoracic or thoracolumbar hemivertebrae for either angular deformity in the coronal plane, or both coronal and sagittal deformity. Vertebral excision was carried out anteriorly alone in two patients. Seven patients had undergone previous posterior spinal fusion. Their mean age at surgery was 13.4 years (6 to 19). The mean follow-up was 78.5 months (20 to 180). The results were evaluated by radiological review of the preoperative, postoperative and most recent follow-up films. The mean preoperative coronal curve was 78.2 degrees (30 to 115) and was corrected to 33.9 degrees (7 to 58) postoperatively, a mean correction of 59%. Preoperative coronal decompensation of 35 mm was improved to 11 mm postoperatively. Seven patients had significant coronal decompensation preoperatively, which was corrected to a physiological range postoperatively. There were no major complications and no neurological damage. We have shown that resection of thoracic and thoracolumbar hemivertebrae can be performed safely, without undue risk of neurological compromise, in experienced hands.

Adolescent↗
PubMed2001

[A study on cellular matrix via cell extraction from bovine pericardium].

OBJECTIVE: To obtain an acellular matrix from bovine pericardial tissue, as a scaffold for tissue engineering of heart valves or cardiovascular patching applications. METHODS: A four step detergent and enzyme link extraction procedure was practiced in this study. The mechanic properties of the acellular matrix were evaluated, and the components were analyzed biochemically. RESULTS: HE staining confirmed the removal of cells and Von Gieson staining showed the integrality of collagen and elastin. Biochemical analysis demonstrated the retention of collagen and some glycosaminoglycans while the percentage of the soluble proteins reduced slightly. The tissue fracture strength and shrinkage temperature made no significant difference after extraction. CONCLUSIONS: The extraction process is effective to remove cells from bovine pericardial tissue while maintains its mechanical strength. This approach may eventually lead to a scaffold for heart valves and cardiovascular patching applications in tissue engineering.

Animals↗
PubMed2000

Eikenella corrodens vertebral osteomyelitis secondary to direct inoculation: a case report.

STUDY DESIGN: A case report. OBJECTIVE: To present a unique method of inoculation with an unusual bacterial organism, Eikenella corrodens, which led to vertebral osteomyelitis and to heighten awareness of different bacterial organisms that may cause orthopedic infections. SUMMARY OF BACKGROUND DATA: E. corrodens has been known to cause orthopedic infections for more than 20 years. The usual mechanism is from "Fight bite" injuries to the hand or metacarpal phalangeal joint. Eikenella osteomyelitis of the vertebral body is extremely rare. METHODS: A 65-year-old man from Indonesia developed slowly progressive vertebral collapse and worsening neck pain. History suggested a previous pharyngeal injury while eating fish. Work up for malignancy was negative, and imaging studies were suggestive of osteomyelitis. An open biopsy and culture as well as fusion were performed for treatment of the osteomyelitis. RESULTS: After a complete work up was undertaken, cultures grew out E. corrodens as the causative organism of this patient's osteomyelitis. Computed tomography scan and history were consistent with inoculation of the paravertebral space with E. corrodens secondary to a fish bone transgressing the patient's pharynx. The patient was treated with surgery and the appropriate antibiotics and healed without any significant sequela. CONCLUSION: Vertebral osteomyelitis due to E. corrodens is extremely rare. Direct inoculation as a cause of vertebral osteomyelitis with Eikenella has never been reported. If diagnosed properly with appropriate cultures and antibiotic sensitivities, Eikenella osteomyelitis can be treated successfully according to standard orthopedic practices including debridement, fusion, and appropriate antibiotics. Awareness of unusual bacteria as potential causative organisms of osteomyelitis is imperative for appropriate treatment.

Aged↗
PubMed2000

Biphasic material properties of lytic bone metastases.

It is necessary to prescribe the mechanical properties of tumor tissue when modeling the metastatically involved skeleton for clarifying the mechanisms of fracture. This study provides mechanical property data for lytic bone metastases. Specimens of human lytic tumor were tested under a confined compression uniaxial creep protocol and the mechanical behavior of the tumor tissue was modeled using linear biphasic theory. The tumor tissue was found to have an aggregate modulus (HA) of 3.6 +/- 1.6 kPa and a hydraulic permeability (k) of 0.59 +/- 0.46mm4 N(-1) s(-1). Tumors with a higher percentage of stromal content were found to be stiffer and more permeable than those with a more cellular composition. No significant differences in aggregate modulus or hydraulic permeability were found between lytic metastases of different types. These data are useful for the development of models to simulate the behavior of the metastatically involved skeleton using theoretical or finite-element analysis techniques and also have significance for developing effective tumor-drug-transport models. We anticipate that specification of the mechanical behavior of this tissue may help to better focus future treatment of lytic bony metastases through better assessment of fracture risk and improved drug delivery.

Biomechanical Phenomena↗
PubMed1999

Thromboembolic complications after major thoracolumbar spine surgery.

STUDY DESIGN: Adult spinal surgery patients were studied prospectively to determine the incidence of subclinical deep venous thrombosis. An overlapping group of patients was reviewed retrospectively for symptomatic thromboembolism. OBJECTIVES: To determine the incidence of symptomatic and asymptomatic thromboembolism in spinal surgery patients. SUMMARY OF BACKGROUND DATA: Although thromboembolic complications are known to occur after spinal operations, there are limited published data on the incidence of pulmonary embolus or deep venous thrombosis after major spinal surgery. METHODS: One hundred sixteen adult spinal surgery patients were examined with duplex ultrasound to determine the incidence of deep venous thrombosis. Seventy-three of these patients also underwent lung perfusion scans to look for subclinical pulmonary embolism. A retrospective review was conducted of symptomatic thromboembolic complications occurring in a 2-year period at the authors' center. Three hundred and eighteen major spinal reconstructive procedures were performed during the period reviewed, which included the period of the prospective study and therefore the patients of the prospective group. Thigh-length compression stockings and pneumatic compression leggings were used for prophylaxis in all patients. RESULTS: One patient had an asymptomatic iliac vein thrombosis, and seven patients had symptomatic pulmonary embolism (2.2%). Six of the symptomatic pulmonary emboli occurred after combined anterior/posterior spinal fusions (6%), whereas only one occurred after posterior decompression and fusion (0.5%). CONCLUSIONS: Duplex ultrasound appeared insensitive for diagnosing clots before embolization in this patient group. Simple mechanical prophylaxis for thromboembolism, which may be adequate for patients undergoing posterior procedures, may not be as protective for patients undergoing combined anterior/posterior spine surgery.

Female↗
PubMed1999

Patient outcomes after decompression and instrumented posterior spinal fusion for degenerative spondylolisthesis.

STUDY DESIGN: A retrospective study of patient outcomes after decompression and fusion for degenerative spondylolisthesis, using the SF-36 survey and a functional questionnaire. SUMMARY OF BACKGROUND DATA: In recent studies, patient outcomes have been examined more specifically; however, detailed functional outcomes are not available nor have widely used outcomes instruments been administered. METHODS: Thirty patients aged more than 40 years (average, 60.1 years) who had degenerative spondylolisthesis were evaluated after decompression and instrumented posterior fusion. Charts and radiographs were also reviewed. Questionnaires were administered by telephone, and consisted of the Medical Outcomes Study short form (SF-36) and 27 questions designed to evaluate function, quality of life, medication usage, and satisfaction with surgical results. RESULTS: Ninety-three percent of patient's were satisfied with their outcomes. Patients improved significantly in their ability to perform heavy and light activities, participate in social activities, sit, and sleep (P < 0.001) and also improved in pain, depression, and medication usage (P < 0.0001). SF-36 data showed significantly better overall assessment of health in all categories than that in a published cohort of patients with low back pain. The current study group also showed no difference in seven of eight categories when compared with the general population. Fusion rate was 93% at an average of 128 days. Three patients required reoperation: two for pseudarthrosis and one for a deep infection. A poorer outcome, scored by the SF-36, was associated with greater preoperative stenosis (P < 0.05) or occurrence of a complication (P < 0.05). CONCLUSIONS: Patients treated with decompression and fusion for degenerative spondylolisthesis had improved functional outcomes, when measured by a disease-specific questionnaire and by widely used instruments.

Activities of Daily Living↗
PubMed1999

Management of spondylolysis and spondylolisthesis in the pediatric and adolescent population.

Spondylolysis and low-grade spondylolisthesis are diagnoses that, for most patients, have a benign prognosis and can be managed nonoperatively. For most symptomatic patients for whom this management fails, fusion in situ yields satisfactory and lasting results and remains the gold standard against which other surgical treatment must be compared. Patients with high-grade slips and slip angles may benefit from instrumented fusion in situ or combined anterior/posterior procedures, or may be considered for reduction and fusion. Reduction maneuvers are technically demanding and carry significant risk of neurologic injury. Surgical experience and in-depth understanding of the indications, the complications, and, especially, the limitations of each technique are required.

Adolescent↗
PubMed1998

Nutritional depletion in staged spinal reconstructive surgery. The effect of total parenteral nutrition.

STUDY DESIGN: A prospective randomized study evaluating nutritional depletion in spine surgery patients. OBJECTIVE: To determine whether use of total parenteral nutrition (TPN) in patients undergoing staged spinal reconstructive procedures could affect their nutritional parameters or decrease their complication rates. SUMMARY OF BACKGROUND DATA: Several studies have shown that nutritional depletion occurs after major spinal surgery and that patients undergoing staged spinal surgery may be at particular risk of nutritional loss and its complications. METHODS: Forty adult patients undergoing staged spinal reconstructive surgery were randomized as to whether they received TPN postoperatively. Nutritional parameters, including skin fold measurement and albumin, pre-albumin, transferrin, and total lymphocyte counts, were obtained pre-operatively and at regular intervals. RESULTS: Five patients did not complete the study, leaving 35 patients for analysis. There was a significant decrease in incidence of albumin and pre-albumin depletion for the patients who did not receive TPN compared with those who did receive TPN (P < 0.025, P < 0.006, respectively). Patients with depleted albumin or pre-albumin counts were more likely to develop other postoperative infectious complications such as pneumonia or urinary tract infections (P < 0.035). There were no statistically significant differences in wound complications in this small patient study. There were no complications secondary to use of the TPN. CONCLUSIONS: For complex patients requiring staged anterior/posterior surgery, TPN appears to significantly lessen the decrease in nutritional parameters. Because depletion of nutritional parameters appears to correlate with an increased likelihood of perioperative infectious complications, use of TPN may result in a decrease of such complications in these patients.

Adult↗
PubMed1998

Effect of the pedicle and posterior arch on vertebral body strength predictions in finite element modeling.

STUDY DESIGN: A finite element study to predict the contribution of the pedicles and the posterior arch to vertebral body strength. OBJECTIVE: To determine the effect of the pedicle and posterior arch on strain distributions occurring within the vertebral body under axial compressive loading. SUMMARY OF BACKGROUND DATA: Posterior vertebral body fracture can arise from high-impact or normal loading in bones compromised by osteoporosis or neoplasm and can result in spinal canal encroachment. Anatomically, the pedicles and posterior arch have a potential role as a structural buttress to the posterior vertebral body wall. However, most finite element models used to investigate vertebral body strength have neglected these structures. METHODS: Three 3-dimensional finite element models were developed of L1, incorporating anatomic curvature, with varying degrees of posterior element inclusion (no pedicle, pedicle, and pedicle and posterior arch). Three cases were analyzed with each model: 25% dehydrated disc, normal healthy disc, and uniform pressure loading. Outcome variables were the maximum von Mises strains and the displacement of the posterior wall into the spinal canal. RESULTS: Inclusion of the posterior arch resulted in substantial decreases in maximum strain and posterior wall displacement under all loading configurations using transversely isotropic trabecular bone properties. No changes in maximum strains or displacements were recorded in the pedicle model, compared with that observed in the no-pedicle baseline case. CONCLUSIONS: The pedicle functions as a structural buttress, providing support to the posterior wall of the vertebral body when constrained through the posterior arch. To yield more accurate vertebral body strength predictions from finite element modeling, the posterior arch should be included.

Biomechanical Phenomena↗
PubMed1997

Internal fixation in the osteoporotic spine.

The presence of osteoporosis in patients who are candidates for spinal surgery can affect preoperative planning. These patients may not need instrumentation for a successful surgical result, but if use of instrumentation is indicated because of instability or deformity, certain principles should be observed. These include using multiple sites of fixation, accepting lesser degrees of deformity correction, and avoiding ending the instrumentation within kyphotic segments. Advances in perioperative medical management, as well as improved instrumentation systems, may also contribute to improving patient outcomes.

Adult↗
PubMed1997

Carbonated apatite cement augmentation of pedicle screw fixation in the lumbar spine.

STUDY DESIGN: Biomechanical testing with human cadaveric lumbar vertebral bodies was used to determine the utility of an injectable carbonated apatite cancellous bone cement for improving the structural performance of pedicle screws subjected to axial pull-out or transverse cyclic loading. OBJECTIVES: To ascertain whether augmentation with a carbonated apatite cement can enhance pedicle screw fixation in the lumbar spine. SUMMARY OF BACKGROUND DATA: The beneficial effects of polymethylmethacrylate augmentation on pedicle screw pull-out strength have been demonstrated. Cancellous bone cement, however, may provide an attractive alternative in this application, as it is remodelable, biocompatible, and nonexothermic. METHODS: Forty-three cadaveric lumbar vertebral bodies were instrumented with pedicle screws. In 20 of these specimens, axial pull-out strength was compared between the control screws and those augmented with cancellous bone cement. In the remaining 23 specimens, the screws were loaded in the superior-inferior direction with a peak displacement of +/- 1 mm at a frequency of 3 Hz for 5000 cycles. Three parameters were calculated from the force-versus-time data: 1) the energy dissipated, 2) the peak force at the start of the test, and 3) the peak force at the end of 5000 cycles. RESULTS: The pull-out strength of the augmented pedicles averaged 68% greater than that of the control side. In response to cyclic loading, all measures of bio-mechanical performance improved 30-63%. CONCLUSIONS: The data suggest that augmentation with this carbonated apatite cancellous bone cement can enhance immediate screw fixation.

Adult↗