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Biomedical subjects

S S Hu

Publications and source records attributed to S S Hu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Revision of failed lumbar fusions. A comparison of anterior autograft and allograft.

STUDY DESIGN: The radiographic and clinical results of two different anterior structural grafts were compared in 38 patients who had combined anterior-posterior revision surgery for failed lumbar fusion. OBJECTIVES: Failed lumbar fusion surgery, such as pseudarthrosis or flatback deformity, may result in disabling pain. The optimum revision technique has yet to be defined. The authors of the current study sought to determine which of two different types of anterior graft yields the best results. SUMMARY OF BACKGROUND DATA: Posterior procedures for revision of a failed lumbar fusion have not yielded reliably successful results. A combined anterior-posterior approach may be effective in restoring sagittal balance and enhancing fusion rates. Recent studies have shown femoral ring allografts to be effective in lumbar fusion revision, but no studies have compared these with other types of structural grafts. METHODS: Thirty-eight patients with pseudarthrosis were treated with combined anterior-posterior lumbar spine fusion using either femoral ring allografts (26 patients) or tricortical iliac autografts (12 patients). Radiographic follow-up examination and retrospective patient self-assessment questionnaires were used to evaluate outcomes. Results were assessed by independent reviewers after a mean follow-up period of 35 months. RESULTS: Radiographic follow-up examination revealed acceptably low pseudarthrosis rates for structural autografts (0%) and allografts (6%). The questionnaires revealed significant improvement in pain for both groups. Allograft patients showed greater improvement in function, less pain medication usage, and higher overall success rates (83%) than autograft patients (64%). CONCLUSIONS: Femoral ring allografts are as effective, clinically and radiographically, as tricortical iliac autografts when used as an anterior structural element in revision lumbar spine fusion in patients who have undergone multiple surgical procedures for pseudarthrosis or flatback deformity. The slightly greater improvement for the allograft group needs to be confirmed in a larger study.

Adult↗
PubMed1997

Postural imbalance and vibratory sensitivity in patients with idiopathic scoliosis: implications for treatment.

Sporadic research reports of decreased proprioception and balance problems have been reported in subjects with idiopathic scoliosis, yet these sensory motor deficits have not been addressed in conservative clinical management programs. The purpose of this study was to compare both balance reactions and vibratory sensitivity (as an estimate of proprioception) in patients with idiopathic scoliosis (N = 24) and age-matched controls (N = 24). Balance was measured by the ability to pass a series of simple static and complex sensory-challenged balance tasks. Vibratory thresholds were measured with the Bio-Thesiometer at the cervical spine, wrist, and foot. Compared with age-matched controls, regardless of curve severity or spinal fusion, the subjects with idiopathic scoliosis had similar simple static balance responses when the somatosensory system was stable (with or without vision or head turning), but they were significantly more likely to fail the complex, sensory-challenged balance tasks when the somatosensory system was challenged by an unstable position of the feet, particularly when the eyes were closed. The vibratory thresholds were similar in subjects with scoliosis and their age-matched controls, but individuals with moderate to severe scoliosis (> 25 degrees) had significantly higher vibratory thresholds than those with mild curves. These findings suggest there may be problems with postural righting in patients with idiopathic scoliosis, particularly when the balance task challenges the vestibular pathways. Although vibration sensitivity did not distinguish normal healthy individuals from individuals with idiopathic scoliosis, those with more severe scoliotic curves appear to have a high threshold to vibration. These balance and vibratory differences could either be interpreted as etiologic risk factors or as consequences of spinal asymmetry. In either case, given that curves can continue to progress even into the adult years, improving the ability to right the body with gravity could help maintain the balance of the spine despite structural asymmetry.

Adolescent↗
PubMed1996

Reduction of high-grade spondylolisthesis using Edwards instrumentation.

STUDY DESIGN: Sixteen patients with high-grade spondylolisthesis (Grade III or higher) who underwent posterior decompression and reduction using the Edwards Modular Spine System (Spinal System Ltd., Baltimore, MD) were reviewed clinically and radiographically. OBJECTIVES: This study was undertaken to determine the efficacy of one specific reduction technique to treat patients with high-grade spondylolisthesis where there has been a loss of sagittal balance, intractable pain, and/or neurologic deficit. SUMMARY OF BACKGROUND DATA: The average age of our patients was 20 years. Preoperative slippage averaged 89%; preoperative slip angle averaged 50 degrees. Indications for surgery were back and leg pain, progression of slippage (in 9 patients), and/or the inability to stand upright with the knees straight. METHODS: Pre- and postoperative radiographic films were reviewed. The percent slip and the slip angle were measured pre- and postoperatively. Clinical data were obtained via chart review, telephone interview, and/or office visit. RESULTS: The average preoperative slip was 89%; postoperatively, the average slip was 29%. Slip angle averaged 50 degrees preoperatively and improved to a postoperative average of 24 degrees. Three patients had neurologic impairment postoperatively; one did not resolve. Four patients had hardware failure; all were revised. Ten patients had an excellent result, 5 patients had a good result, and 1 patient had a fair result. The average follow-up was 3.8 years. CONCLUSION: This procedure is technically demanding and is subject to the known risks of surgical treatment for high-grade spondylolisthesis. For select patients, it may be effective for reducing severe deformity and can be expected to afford good to excellent results. Improved sacral fixation may reduce the rate of hardware-related complications.

Adolescent↗
PubMed1996

Pediatric spinal infections.

A high index of suspicion for spinal infection and an appropriate and prompt diagnosis are essential for the treatment of pediatric spinal infections. A 3-week course of antibiotics and supportive therapy is effective in the majority of cases of discitis, the most common pediatric spinal infection. Patients who are not toxic may be treated with bracing, or with casting alone in many cases. Neurologic deficit or a failure to respond to early treatment requires more aggressive measures, including biopsy or surgical debridement. It is essential to diagnose rare but serious conditions such as epidural abscess, tuberculosis, or opportunistic infections in patients at risk. The authors stress that clinical evaluation and appropriate diagnosis are critical for prevention of permanent neurologic damage or late bony deformity.

AIDS-Related Opportunistic Infections↗
PubMed1996

Patient outcomes after spinal reconstructive surgery in patients > or = 40 years of age.

This study provides outcome data on the quality of life in 84 patients 40 years of age or older who had spinal reconstructive surgery. A 30-min questionnaire covering the patients' pre- and postoperative functional status, expectations for surgery, medication use, quality of life, and overall satisfaction was administered via telephone by a trained interviewer. Clinical data were obtained from chart and radiographic review. The majority of the patients had back or leg pain as their indication for surgery. Diagnoses included kyphosis, scoliosis, spinal stenosis, spondylolisthesis, and failed surgery. Overall satisfaction with functional status and surgical outcome was 81%, and there was significant improvement in most functional measures. This study suggests that improved qualify of life for the majority of appropriately selected spinal reconstruction patients is achievable in this mature population.

Adult↗
PubMed1995

Instrumentation of the cervicothoracic junction after destabilization.

STUDY DESIGN: The biomechanics of three different instrumentation constructs applied at the destabilized cervicothoracic junction were evaluated. OBJECTIVES: To find an efficient way in restoring stability of the cervicothoracic junction in cases with and without laminectomy. SUMMARY OF BACKGROUND DATA: Different instrumentation techniques have been evaluated biomechanically and used clinically for managing instabilities between the fourth and sixth cervical vertebrae. These constructs have not been evaluated at the cervicothoracic junction. METHODS: Six human spines were tested nondestructively in axial torsion, flexion, and extension with the C6-T2 motion segments left unconstrained. The three-dimensional displacements and rotations between C7 and T1 vertebrae were measured using a sonic digitizer. After intact testing, a distractive-flexion Stage 3 cervical spinal injury was simulated surgically between C7 and T1. The specimens underwent sequential instrumentation and mechanical testing with three constructs: posterior Synthes lateral mass plate, posterior pediatric Cotrel-Dubousset rod system with lamina hooks and a crosslink, and anterior Synthes cervical locking plate. RESULTS: Posterior stabilization techniques had statistically more stiffness than anterior plates. The Cotrel-Dubousset system offered the largest stiffness ratio (instrumented/intact) in flexion, extension, and rotation. There was no statistical difference between posterior plates and Cotrel-Dubousset instrumentation. The stiffness of the anterior plate did not differ significantly from the intact spine. CONCLUSION: Our data show that instability of the cervicothoracic junction can be efficiently restored by either anterior plates, posterior plates, or posterior hook-rod constructs (Cotrel-Dubousset). Posterior constructs showed increased stiffness over anterior plates.

Aged↗
PubMed1995

The antiproliferative activity of c-myb and c-myc antisense oligonucleotides in smooth muscle cells is caused by a nonantisense mechanism.

Smooth muscle cell (SMC) proliferation is thought to play a major role in vascular restenosis after angioplasty and is a serious complication of the procedure. Developing antisense (AS) oligonucleotides as therapeutics is attractive because of the potentially high specificity of binding to their targets, and several investigators have reported inhibition of SMC proliferation in vitro and in vivo by using AS strategies. We report here the results of our experiments on vascular SMCs using AS oligonucleotides directed toward c-myb and c-myc. We found that significant inhibition of SMC proliferation occurred with these specific AS sequences but that this inhibition was clearly not via a hybridization-dependent AS mechanism. Rather, inhibition was due to the presence of four contiguous guanosine residues in the oligonucleotide sequence. This was demonstrated in vitro in primary cultures of SMCs and in arteries ex vivo. The ex vivo model developed here provides a rapid and effective system in which to screen potential oligonucleotide drugs for restenosis. We have further explored the sequence requirements of this non-AS effect and determined that phosphorothioate oligonucleotides containing at least two sets of three or four consecutive guanosine residues inhibit SMC proliferation in vitro and ex vivo. These results suggest that previous AS data obtained using these and similar, contiguous guanosine-containing AS sequences be reevaluated and that there may be an additional class of nucleic acid compounds that have potential as antirestenosis therapeutics.

Animals↗
PubMed1994

Thermal degradation of injectable epinephrine.

The degradation of epinephrine in USP injectable cartridges was investigated under different heating conditions. Epinephrine (EPI) and EPI sulfonic acid (EPI-SA) levels in 1:10,000 (0.1 mg/mL) EPI injectable solutions subjected to either cyclical (65 degrees C for 8 hr/d for 4 to 12 weeks) or constant (65 degrees C for 7 days) heating were determined using high-pressure liquid chromatography with diode array and electrochemical detection. Constant (169 total hours of heat exposure) heating resulted in complete degradation of both compounds and dark brown discoloration of the solution. Cyclical heating (672 total hours of heat exposure) resulted in a 31% reduction in EPI concentration and a 225% increase in EPI-SA concentration with no discoloration of the solution. In laboratory-prepared solutions, the degradation of EPI and the formation of EPI-SA was found to be dependent on sodium metabisulfite concentration and the duration of cyclical heating. These results indicate that the thermal stability of EPI and the formation of EPI-SA depends on the method of heat exposure and the amount of bisulfite present in the solution.

Chromatography, High Pressure Liquid↗
PubMed1994

[Clinical and morphologic classification of valve replacement with giant heart].

From Apr. 1977 to Dec. 1992, 285 patients with giant heart (CTR > 0.70) underwent valve replacement. According to the index of cardiac chamber enlargement, the patients were clinically and morphologically classified in to four types. Type of left atrium (153 cases, 56.3%) is most common and has good surgical result. The operative mortality was reduced from 11.1% to 1.3%. Type of left ventricle (42, 15.2%) was high risk for surgical treatment, the operative mortality was 33.3%. Type of right cardiac enlargement (17 cases) is less common than other types, and is mainly for tricuspid valve incompetence. Type of total cardiac enlargement was found in 60 cases (22.1%), it was conventionally complicated with the disfunction of other organs with a higher operative mortality of 23.3%. We conclude that this classification represents the degree of cardiac chamber enlargement and the severity of heart disfunction, and has good coincidence with surgical result. It is helpful to identifying operative candidate for valve replacement with giant heart.

Adolescent↗
PubMed1994

[Pathological study of secondary thymic atrophy caused by steroid hormone in mice].

According to the pathological observations on BALB/c mice after being given steroid hormone, the following results were obtained: secondary thymic atrophy could be observed 24 hours after steroid therapy. The degree of atrophy correlated with the amount of medication and duration of therapy; the weight and pathological changes under light and electron microscope examination almost returned to normal 7 days after the drug was stopped except in individual animals. Our study indicated that secondary atrophy of the thymus can be reversed after elimination of the pathogenic factor.

Animals↗
PubMed1993

Sacral screw loads in lumbosacral fixation for spinal deformity.

Fixation to the sacrum and pelvis is a problem in the operative treatment of spinal deformity. Previous testing of pedicle screws address axial pull-out strength, yet how screws are loaded in vivo remains unknown. The goals of this study were to determine the loads experienced by sacral screws when loaded as part of Cotrel-Dubousset (CD) sacral instrumentation and whether different anterior grafting methods would effect screw loads. Sacral screws were modified to become transducers capable of measuring axial and bending loads. The screw transducers were incorporated into the sacral fixation of CD instrumentation in seven calf spines. Specimens were loaded to simulate flexion. The sacral screws carried axial loads (1.1 N/[Nm of load]) and bending moments (1.1 Nm/[Nm of load]). The results suggest bending of the sacral screws may be important in their failure, and screw loading was not dependent on graft types used.

Animals↗
PubMed1993

The effect of surgical decompression on neurologic outcome after lumbar fractures.

From 1980 until 1989, 69 patients with lumbar fractures resulting in incomplete paraparesis were admitted to the authors' medical center for treatment. Thirty had anterior vertebrectomy, including 18 who had posterior instrumentation and four who had anterior instrumentation. Twenty-two patients were treated with a posterolateral decompression and fusion, including four who also required an anterior decompression. Nineteen of the remaining 21 patients required posterior spine instrumentation and fusion only. The American Spinal Injury Association (ASIA) motor index score was determined for each patient pre- and postoperatively and used to compare these three treatment groups. Average follow-up period for the patients was 19 months. The improvement in ASIA motor score for all patients treated with decompression averaged 10 and similar improvement was obtained in those who were treated with posterior decompression (10.2 points). The average improvement in those who had vertebrectomy was 9.9 points. For those who had fusion without decompression, average improvement was 4.2 points. Comparing those patients who were surgically decompressed, either anteriorly or posteriorly, with those patients who only underwent fusion, the difference in neurologic improvement was statistically significant. Neurologic outcome after lumbar fractures is improved by surgical decompression. The neurologic outcome results were similar after anterior and posterior decompression.

Follow-Up Studies↗
PubMed1992

Osteoporosis after spinal cord injury.

Dual-photon absorptiometry characterized bone loss in males aged less than 40 years after complete traumatic paraplegic and quadriplegic spinal cord injury. Total bone mass of various regions and bone mineral density (BMD) of the knee were measured in 55 subjects. Three different populations were partitioned into four groups: 10 controls (healthy, age matched); 25 acutely injured (114 days after injury), with 12 reexamined 16 months after injury; and 20 chronic (greater than 5 years after injury). Significant differences (p less than 0.0001) in bone mass mineral between groups at the arms, pelvis, legs, distal femur, and proximal tibia were found, with no differences for the head or trunk. Post hoc analyses indicated no differences between the acutely injured at 16 months and the chronically injured. Paraplegic and quadriplegic subjects were significantly different only at the arms and trunk, but were highly similar at the pelvis and below. In the acutely injured, a slight but statistically insignificant rebound was noted above the pelvis. Regression techniques demonstrated early, rapid, linear (p less than 0.0001) decline of bone below the pelvis. Bone mineral loss occurs throughout the entire skeleton, except the skull. Most bone loss occurs rapidly and below the pelvis. Homeostasis is reached by 16 months at two thirds of original bone mass, near fracture threshold.

Absorptiometry, Photon↗
PubMed1992

The effect of surgical intervention on rehabilitation time in patients with thoracolumbar and lumbar spinal cord injuries.

One hundred forty-seven patients with unstable low thoracic and lumbar fractures were examined. All patients had significant neurologic injuries. Ninety-one patients exhibited incomplete lesions whereas fifty-six had complete lesions. Age, sex, cause of injury, fracture location, fracture mechanism, and complications were recorded and analyzed. The average follow-up was 25 months (range 2-148). Incomplete neurologic lesions demonstrated a significant increase in ASIA motor points if both decompression and stabilization were performed at the same operative sitting. When decompression was performed before stabilization a decrease in improvement was noted. Patients with complete lesions demonstrated a significant reduction in rehabilitation time if stabilization was augmented with sublaminar wires rather than Drummond wires or Harrington rods alone.

Adult↗
PubMed1987

Features of developing ferret tracheal epithelium: ultrastructural observations of in vivo and in vitro differentiation of ciliated cells.

Ultrastructural features of the developing, surface epithelium of ferrets from birth to 28 days of age were characterized. Progressive ciliogenesis in vivo was observed, beginning with cells covering the membranous portion of the trachea. Emerging cilia appeared in ultrathin sections and by scanning electron microscopy at sites correlating with accumulation of integral membrane particles seen in freeze-fracture preparations. Two patterns of ciliogenesis were observed: (1) the random emergence of cilia over the apical cell surface, and (2) initial emergence of cilia at the peripheral boundary of the luminal border of individual cells. Novel, ringlike structures were observed on the surfaces of nonciliated cells at all ages studied. Active ciliogenesis as well as the appearance of ring structures also were documented in the superficial epithelium from 1- to 5-day-old animals maintained in vitro for up to 4 days.

Aging↗
PubMed1986

Advances in the design of special cryosurgical apparatus in China.

Advances in the design of special cryobiomedical apparatus and a review of the trend of developments in the field of cryosurgery in China are discussed. The typical structure of two special cryoprobes for treatment deep in the body and the technology of designing these probes are presented in detail. Some cases which are treated successfully with the above cryoprobes will also be discussed. The experimental aspects of heat transfer in frozen tissue and of the temperature profiles both of a human brain during surgery and of the cryoprobe are described. Other improvements in the field of cryosurgical devices, e.g., four main ways of attaching freezing tips to cryoprobes during surgery and an LN2 transfer tube with high dexterity are also presented. Finally, the development of commercial cryosurgical apparatus in China is also discussed.

Brain Neoplasms↗