Yang-Hwei Tsuang

An ultra-weak chemiluminescence study on oxidative stress in rabbits following acute thermal injury

It is not easy to detect oxygen free radicals directly because of their very short half-life. In the present study, a sensitive ultra-weak chemiluminescence detector was used to detect the generation of oxygen free radicals following thermal injury. Twelve New Zealand white rabbits were used in this study. After anesthesia, the bilateral hind-limbs were exposed to 100 degrees C water for 30 s. Six control animals were exposed to 22 degrees C water to act as a control. The chemiluminescence of whole blood and visceral organs were measured with both luminol-amplified t-butyl hydroperoxide-initiated and lucigenin-initiated methods. The results showed that chemiluminescence of blood was affected significantly by acute thermal injury. The chemiluminescence of blood increased significantly at 1 h following acute thermal injury, reached a peak at 2 h, then decreased but still remained above the control level at 4 h following thermal injury. The results for TBHP-initiated chemiluminescence from visceral organs following acute thermal injury were much higher than that of the control rabbits. The effects of lucigenin-initiated tissue chemiluminescence following acute thermal injury were not statistically significant. It is suggested that the decreased vascular antioxidant activity following local thermal injury is partially contributed by the superoxide pathway; while, the remote pathophysiologic events are mediated by the defective scavenging defenses.

Traumatic dislocation of the hip.

Of 125 patients with traumatic dislocation of the hips treated, 96 were reviewed retrospectively; 80 were males and 16 females with an age range from seven to 81 years (mean, 33.5 years). Motorcycle accidents were the leading cause of traumatic dislocation in this series (40 cases, 42%). Associated injuries were found in 68 cases (70.8%). Seventy-seven hips (80%) were reduced within 24 hours. In follow-up periods ranging from 15 months to 18 years (mean, 7.5 years), 56 patients had excellent or good results (58.3%). Statistical analysis of the clinical results showed that those patients with simple dislocations had better functional recovery. The earlier the reduction, the better the results. Associated injuries affected prognoses. Good results were obtained in patients with early, stable, and accurate reductions by either closed or open methods.

Direct effects of caffeine on osteoblastic cells metabolism: the possible causal effect of caffeine on the formation of osteoporosis

BackgroundCaffeine consumption has been reported to decrease bone mineral density (BMD), increase the risk of hip fracture, and negatively influence calcium retention. In this study, we investigated the influence of caffeine on the osteoblasts behaviour.MethodOsteoblasts derived from newborn Wistar-rat calvaria was used in this study. The effects of various concentrations of caffeine on bone cell activities were evaluated by using MTT assay. Alkaline phosphatase (ALP) staining, von Kossa staining and biochemical parameters including ALP, lactate dehydrogenase (LDH), prostaglandin E2 (PGE2) and total protein were performed at day 1, 3, and 7. DNA degradation analysis under the caffeine influence was also performed.Results and discussionThe results showed that the viability of the osteoblasts, the formation of ALP positive staining colonies and mineralization nodules formation in the osteoblasts cultures decreased significantly in the presence of 10 mM caffeine. The intracellular LDH, ALP and PGE2 content decreased significantly, the LDH and PGE2 secreted into the medium increased significantly. The activation of an irreversible commitment to cell death by caffeine was clearly demonstrated by DNA ladder staining.ConclusionIn summary, our results suggest that caffeine has potential deleterious effect on the osteoblasts viability, which may enhance the rate of osteoblasts apoptosis.

Menadione-induced cytotoxicity to rat osteoblasts

Abstract. Oxygen-derived free radical injury has been associated with several cytopathic conditions. Oxygen radicals produced by chondrocytes is an important mechanism by which chondrocytes induce matrix degradation. In the present study, we extend these observations by studying oxidative processes against osteoblasts. Osteoblasts were mixed in in vitro culture with 200 μM menadione. The cytotoxic effect of menadione-induced oxidative stress was monitored by lucigenin- or luminol-amplified chemiluminescence, tetrazolium assay and immunocytochemical study. Results showed that adding menadione induces an oxidative stress on osteoblasts, via superoxide and hydrogen peroxide production, that can be eradicated by superoxide dismutase (SOD) and catalase in a dose-dependent manner. Catalase and the appropriate concentration of dimethyl sulfoxide have a protective effect on cytotoxicity induced by menadione, whereas SOD does not. Menadione-treated osteoblasts have a strong affinity for annexin V, and the nuclei are strongly stained by TUNEL (TdT-mediated dUTP nick-end labelling). The results suggest that menadione-triggered production of reactive oxygen species leads to apoptosis of osteoblasts.

The effect of a new anular repair after discectomy in intervertebral disc degeneration: an experimental study using a porcine spine model.

Study Design. In vitro and in vivo studies to assess the effect of direct anular repair on subsequent degeneration of intervertebral discs (IVDs). Objective. To assess whether a new suturing method could provide sealing effect on IVD after discectomy, and influence degenerative process of IVD. Summary of Background Data. Recurrent disc herniation and subsequent disc degeneration are major problems after discectomy. Anular repair can reduce the risk of recurrence, but its effect on disc degeneration needs more investigation. Methods. A new suturing technique, the modified purse-string suture (MPSS), was designed for direct closure of anular incision. Intact motion segments of porcine lumbar spine were used to validate this technique in resisting disc pressure under mechanical loadings. A transverse slit incision was made in the anterior anulus of porcine cervical discs, with or without sealing of the anular defect by this suturing method. Magnetic resonance imaging grading was recorded before and after surgery. Anular healing was assessed histologically and gene expression of aggrecan, collagen type I, II, and matrix metalloproteinase-13 in nucleus pulposus were investigated. Results. The average failure force of axial compression was 1150.3 ± 121.1 N for a simple suture, and 2917.9 ± 627.6 N for a MPSS. Cyclic loading test showed that the repaired discs succeeded against repeated compression forces. Magnetic resonance imaging and gross appearances showed lesser degenerative changes in repaired discs than in injured discs at each time period. In repaired discs, mRNA expression of aggrecan and type II collagen downregulated slightly with time, whereas it decreased rapidly and persistently in unrepaired discs. Histologic findings showed primary healing of outer anular tract in repaired discs. Conclusion. In this pilot study, the MPSS can provide effectively sealing for damaged anulus to withstand stresses. Direct repair of anular incision by this suturing method does significantly slow down degenerative process within discs after discectomy.

Failure of stimulated skeletal muscle mainly contributed by passive force: an in vivo rabbit model

OBJECTIVE: To evaluate the role of active and passive muscle forces in the failure mechanism of stimulated muscle. DESIGN: An in vivo rabbit model. BACKGROUND: Eccentric contractions can result in a greater incidence of muscle injury. However, the relative role of the active and passive muscle force in the failure mechanism of the activated muscle is not well elucidated. METHODS: After anaesthesia, New Zealand white rabbits were fixed in a frame on a materials testing machine. The triceps surae muscle-tendon units were passively stretched to rupture with our without continuous nerve stimulation. The force and muscle length were simultaneously recorded. Active muscle force, passive muscle force, and ratio of the active to passive muscle were calculated and depicted against strain. RESULTS: The results showed that the mean maximal passive force of triceps surae muscle was 293.1 N at a strain of 38%. The mean peak active muscle force was 21.5 N at a strain of 21%. The ratio of active to passive muscle force reached its peak first, followed by the active muscle force, and then the passive muscle force. The ratio of active to passive muscle force at the peak total force was only 3.3%. CONCLUSIONS: The stimulated muscle can exert its maximal response at extreme physiological extension. Injury of the stimulated muscle is caused mainly by passive muscle force.

Viscoplasticity of rabbit skeletal muscle under dynamic cyclic loading

To elucidate the strain effects of dynamic cyclic loading on the skeletal muscle-tendon unit, the muscle-tendon unit of New Zealand white rabbits were tested with different strains and strain rates under ketamine general anaesthesia. The results indicated that the dynamic responses of muscular tissues were both strain and strain-rate dependent with appreciably non-linear characteristic. The muscle-tendon unit behaved viscoelastically below 12% strain; but when stretching more than 16% strain it began to behave plastically. The loading energies and unloading energy are more dependent on strain than on strainrate. RELEVANCE: This study offers firm evidence that plasticity may be one of the important biomechanical properties of the skeletal muscle. The findings in this report imply that the expression of skeletal muscle mechanical behaviour may not be limited to phenomena represented by a composition of elastic and viscous elements. The elongation of skeletal muscle under sustained stretching might be explained by the plastic property. Elucidation of the existence of viscoplasticity in skeletal muscle gives a good reference point to determine the functional capabilities and limitation of muscular tissue.

Progressive Neurological Deficit Secondary to Lumbar Facet Synovial Cysts: Two Case Studies and a Literature Review

This article describes two case studies involving lumbar facet joint synovial cyst causing acute sciatica and progressive neurological deficit. The cases involve women, 57 and 69 years old, respectively. The first patient was presented with left buttock and lower leg pain, numbness and paresthesia, while the second one had progressive right lower leg pain for 3 months. Magnetic resonance imaging revealed a high intensity cystic lesion arising from the facet joint, subsequently causing spinal stenosis and exiting nerve root compression. Surgery was performed, including laminectomy and cyst excision. Microscopic observation confirmed synovial cysts. Following operation, clinical symptoms of the patients improved significantly with no neurological sequelae. Based on our experience with these two patients treated by open surgery in our hospital, this study attempted to more thoroughly elucidate the significance and treatment outcome of a surgically treated lumbar synovial cyst. Moreover, relevant literature was reviewed, with a focus on their clinical presentations, imaging findings, and postoperative surgical outcomes.