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Biomedical subjects

Y Hai

Publications and source records attributed to Y Hai.

9 recordsLinked to original sources
PubMed2001

Quantitative changes in spinal canal dimensions using interbody distraction for spondylolisthesis.

STUDY DESIGN: An experimental study was performed using cadaveric lumbar spines to evaluate the effect of anteriorly or laterally placed interbody distraction implants on the alteration of spinal canal and neuroforaminal dimensions. OBJECTIVES: To quantify changes in the spinal canal and neuroforaminal dimensions using interbody fusion devices inserted at various configurations in cadaveric lumbar spines exhibiting degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Although several clinical studies have demonstrated successful treatment of degenerative spondylolisthesis with anterior interbody fusion, no study has shown the role of interbody distraction in improving lumbar spinal canal and foraminal stenosis. METHODS: Five fresh cadaver lumbar spines exhibiting a degenerative spondylolisthesis or retrospondylolisthesis were used for the study. Computed tomography scans of each specimen and a silicon mold of the left intervertebral foramens were repeated in a consistent manner after pure compressive load (150 lb) was applied to simulate physiologic load (intact case), after two BAK (Sulzer SpineTech Inc., Minneapolis, MN) distraction plugs were anteriorly inserted into the intervertebral disc space (anterior distraction cases), and after one long BAK cage was laterally inserted from the left side (lateral distraction case). The cross-sectional area of the spinal canal was measured from computed tomography images using National Institutes of Health image software (Bethesda, MD). The spinal canal volume was calculated using the cross-sectional area and total scan thickness. Left intervertebral foraminal volumes were calculated from the weight of the silicon mold injected into the foramen. Descriptive statistics and a Student's t test were used to detect statistical differences in the spinal canal and neuroforaminal volumes before and after interbody distraction. RESULTS: The cross-sectional canal area was significantly increased after anterior distraction (35.11%) and lateral distraction (33.14%). The spinal canal volume was markedly increased with anterior distraction (19.92%) and lateral distraction (21.96%). Left foraminal volume was also enhanced by 40.25% for anterior distraction and 41.03% for lateral distraction. CONCLUSIONS: Interbody distraction either by anteriorly inserted plugs or laterally inserted threaded cagescan immediately improve the narrowed canal area and increase spinal canal, as well as foraminal volume for lumbar degenerative spondylolisthesis or retro- spondylolisthesis.

Anthropometry↗
PubMed2000

Posterior lumbar interbody fusion using posterolateral placement of a single cylindrical threaded cage.

STUDY DESIGN: An in vitro biomechanical study of posterior lumbar interbody fusion (PLIF) with threaded cages was performed on 18 bovine lumbar functional spinal units. OBJECTIVES: To compare the segmental stiffness among PLIF with a single long posterolateral cage, PLIF with a single long posterolateral cage and simultaneous facet joint fixation, and PLIF with two posterior cages. SUMMARY OF BACKGROUND DATA: In most cases, PLIF with threaded cage techniques needs bilateral facetectomy, extensive exposure, and retraction of the cauda equina. Posterior element deficiency is detrimental to postoperative segmental stiffness. METHODS: All specimens were tested intact and with cage insertion. Group 1 (n = 12) had a long threaded cage (15 x 36 mm) inserted posterolaterally and oriented counter anterolaterally on the left side by posterior approach with left unilateral facetectomy. Group 2 (n = 6) had two regular-length cages (15 x 24 mm) inserted posteriorly with bilateral facetectomy. Six specimens from Group 1 were then retested after unilateral facet joint screw fixation in neutral (Group 3). Similarly, the other six specimens from Group 1 were retested after fixation with a facet joint screw in an extended position (Group 4). Nondestructive tests were performed in pure compression, flexion, extension, lateral bending, and torsion. RESULTS: The PLIF procedure involving a single cage (Group 1) had a significantly higher stiffness than PLIF with two cages (Group 2) in left and right torsion (P < 0.05). Group 1 had higher stiffness values than Group 2 in pure compression, flexion, and left and right bending, but differences were not significant. Group 3 had a significant increase in stiffness in comparison with Group 1 for pure compression, extension, left bending, and right torsion (P < 0.05). For Group 4, the stiffness significantly increased in comparison with Group 1 for extension, flexion, and right torsion (P < 0.05). Although there was no significant difference between Groups 3 and 4, Group 4 had increased stiffness in extension, flexion, right bending, and torsion. CONCLUSIONS: Posterior lumbar interbody fusion with a single posterolateral long threaded cage with unilateral facetectomy enabled sufficient decompression while maintaining most of the posterior elements. In combination with a facet joint screw, adequate postoperative stability was achieved.

Animals↗
PubMed2000

[Surgical treatment of single level unstable degeneration with foraminal stenosis].

OBJECTIVES: Lumbar spine single level unstable degeneration with foraminal stenosis was treated with unilateral decompression, disc excision, posterolateral interbody fusion utilizing single BAK cage and count-lateral facet joint screw fixation. The short-term and mid-term clinical results were evaluated. METHODS: There were thirty patients (13 male, 17 female) with an average age of 46.5 years. From posterior approach, all patients underwent unilateral decompression, disc excision, interbody fusion with posterolateral inserted single BAK cage, and count-lateral facet joint screw fixation. RESULTS: All patients underwent surgery safely without severe complications occurred such as infection and neurological damages. The average follow-up time was 12 months (6 - 18 months) with complete relief of symptoms. Solid fusion was achieved in all but 2 patients at final follow-up. 90% of the patients obtained successful clinical outcome. CONCLUSIONS: Complete decompression of the neural foramen can relief the symptoms, and interbody fusion utilizing threaded cage can restore the height of disc space and withstand axial loading of the spine. Addition of the facet joint fixation increased the postoperative segment stability and enhances solid fusion. With less invasive and preservation of part of the posterior elements of the lumbar spine and the solid fusion achieved, we consider it a sound procedure for the treatment of single level unstable degeneration with foraminal stenosis of lumbar spine. Long-term follow-up results needs to be observed.

Adult↗
PubMed1997

[Significance of surgical treatment of bursting fracture with CT estimation analysis of the anatomy of pedicle of vertebral arch].

Using CT analysis of 3-D anatomical data of the pedicle of the vertebral arch as a guideline, we standardized the pedicle screw insertion technique. Fourty-six bursting fracture cases were treated using a AF 3-D pedicle screw system with the standard technique and followed up for over 12 months. Comparision was made with the former non-standard technique performed in 72 cases. The results showed that each screw reached the maximum depth with an accurate angle. Comparision of the former non-standard technique showed a significant difference between the two groups. 46 bursting fracture cases obtained anatomical reduction in 3-D and rigid fixation after follow-up for 12 months. Pedicle screw, inserted through the pedicle anatomical axis can reach the maximum depth, that will achieve best stability and ideal clinical result. CT analysis supplies reliable individual data for standardization of pedicle screw insertion.

Adolescent↗
PubMed1996

Global mapping of structural solutions provided by the extended X-ray absorption fine structure ab initio code FEFF 6.01: structure of the cryogenic photoproduct of the myoglobin-carbon monoxide complex.

X-ray methods based on synchrotron technology have the promise of providing time-resolved structural data based on the high flux and brightness of the X-ray beams. One of the most closely examined problems in this area of time-resolved structure determination has been the examination of intermediates in ligand binding to myoglobin. Recent crystallographic experiments using synchrotron radiation have identified the protein tertiary and heme structural changes that occur upon photolysis of the myoglobin--carbon monoxide complex at cryogenic temperatures [Schlichting, I., Berendzen, J., Phillips, G., & Sweet, R. (1994) Nature 371, 808--812]. However, the precision of protein crystallographic data (approximately 0.2 A) is insufficient to provide precise metrical details of the iron--ligand bond lengths. Since bond length changes on this scale can trigger reactivity changes of several orders of magnitude, such detail is critical to a full understanding of metalloprotein structure--function relationships. Extended X-ray absorption fine structure (EXAFS) spectroscopy has the potential for analyzing bond distances to a precision of 0.02 A but is hampered by its relative insensitivity to the geometry of the backscattering atoms. Thus, it is often unable to provide a unique solution to the structure without ancillary structural information. We have developed a suite of computer programs that incorporate this ancillary structural information and compute the expected experimental spectra for a wide ranging series of Cartesian coordinate sets (global mapping). The programs systematically increment the distance of the metal to various coordinating ligands (along with their associated higher shells). Then, utilizing the ab initio EXAFS code FEFF 6.01, simulated spectra are generated and compared to the actual experimental spectra, and the differences are computed. Finally, the results for hundreds of simulations can be displayed (and compared) in a single plot. The power of this approach is demonstrated in the examination of high signal to noise EXAFS data from a photolyzed solution sample of the myoglobin--carbon monoxide complex at 10 K. Evaluation of these data using our global mapping procedures placed the iron to pyrrole nitrogen average distances close to the value for deoxymyoglobin (2.05 +/- 0.01 A), while the distance from iron to the proximal histidine nitrogen is seen to be 2.20 +/- 0.04 A. It is also shown that one cannot uniquely position the CO ligand on the basis of the EXAFS data alone, as a number of reasonable minima (from the perspective of the EXAFS) are observed. This provides a reasonable explanation for the multiplicity of solutions that have been previously reported. The results presented here are seen to be in complete agreement with the crystallographic results of Schlichting et al. (1994) within the respective errors of the two techniques; however, the extended X-ray absorption fine structure data allow the iron--ligand bond lengths to be precisely defined. An examination of the available spectroscopic data, including EXAFS, shows that the crystallographic results of Schlichting et al. (1994) are highly relevant to the physiological solution state and must be taken into account in any attempt to understand the incomplete relaxation process of the heme iron for the Mb*CO photoproduct at low temperature.

Animals↗
PubMed1995

[Biomechanics of AF new 3-d pedical screw system and treatment of 31 patients with unstable thoracolumbar fracture].

For anatomic reduction of the spinal frectures, the 3 dimensional multiple correction forces were needed. Several pedical screw systems were designed for reducion and fixation of the spinal fractures as the AO universal joint system and the RF angle screw system. Because of the contradiction of the universal joint and the fixed angle, a new generation of RF was designed and named AF (atlas fixator) system. This is a new concept of 3-D reduction, without complex structure as universal joint, but has truly 3-D adjustment that allowed to reduce the intra-canal compromise. It also provided rigid fixation to maintain the reduction. Comparison with CD, AO, Steffee, and RF, the AF was truly 3-D reduction in XTZ axis. It provided strong symmetric transmitter orthotic force to correct the deformity. 31 patients with unstable thoracolumbar fractures were treated with the new AF system. 17 had partial (15) or complete (2) neurologic deficits. The AF system provided accurate angle to restore the normal thoracic-lumbar lordosis and to maintain it. All patients had a anatomic reduction by AF system. The spinal canal area increased over 33% by CT scan (P < 0.01). All cases were followed up over 8 months. No one deteriorated neurologically after AF fixation.

Adult↗
PubMed1994

[Adult spondylolisthesis treated with the combination of angled and pushing-pulling pedicle screws].

Altogether 28 patients with degenerative (22 cases), isthmic (4 cases), and post-traumatic (2 cases) spondylolisthesis were treated with a reduction fixation system using both angled and pushing-pulling pedicle screws. Preoperatively, the percentages of the sliprage were < or = 25% in 15 cases, < or = 50% in 11, and < or = 75% in 2 cases. All patients had low-back pain and/or leg pain. Postoperatively, 28 cases obtained a nearly anatomical reduction. The average rate of correction was 98%. There is a significant difference (P < 0.01) compared with preoperation. After reduction, all patients had only two segmental rigid fixations with posterolateral bone grafting or postero-inter-body fusion. 27 cases had satisfactory pain relief postoperatively. No patient deteriorated neurologically with surgery. All patients were followed up for a minimum of 8 months ranging from 8 to 28 months (average 19). At the end of follow-up, in 26 patients correction remained unchanged with X-ray demonstrating radiographic evidence of fusion. Neither pseudarthroses nor significant complications occurred. The new system is a safe and effective pedicular fixation system, it has a three-dimensional correction force that allows for reduction of the spondilolisthesis and fixation of only two segments. It also gives more rigid fixation to maintain the reduction and increase the fusion rate. The new system gives satisfactory results over conventional hook and sub-lamina wire and other segmental spinal pedicle screw instrumentation systems.

Adult↗
PubMed1974

Enhancement of resistance to infectious diseases by oral administration of brewer's yeast.

The effect of oral administration of brewer's yeast on resistance to infectious diseases was studied in laboratory animals. It was shown that there was a significantly increased enhancement of resistance to seasonal respiratory and enteric infections in rhesus monkeys. Similarly, enhanced resistance to experimental chronic infections was observed in mice after yeast administration. A 2-week lag occurred between the initiation of yeast treatment and the expression of enhanced resistance. Study of the mechanism of the yeast-induced enhancement of resistance to infection leads to the conclusion that it is based on in vivo stimulation of phagocytosis, as measured by the "phagocytic index." No effect of brewer's yeast on circulating antibody levels was detected.

Administration, Oral↗