Bilge Bilgic

Time-Dependent Changes in Failure Loads of 3 Biceps Tenodesis Techniques In Vivo Study in a Sheep Model

Background Failure load of the tendon–fixation material–bone unit has a crucial importance for the rehabilitation protocol after tenodesis procedures. Purpose To investigate and compare the time-dependent changes in fixation strengths of 3 proximal biceps tenodesis techniques. Study Design Controlled laboratory study. Methods Two intraosseous techniques (suture sling and tenodesis screw) and 1 extraosseous technique (2 suture anchors) were investigated. Biceps tenodesis was performed on 45 shoulders of 26 sheep, 15 shoulders for each technique. Twelve similar cadaveric sheep shoulders (4 for each technique) provided the day 0 results. Sheep were sacrificed at 3, 6, and 9 weeks, and specimens were tested for the failure load of the tenodeses. Results All 3 tenodesis techniques were found to have similar failure loads at all time intervals tested. All 3 curves remained below the failure load of the intact tendon (862 ± 96 N) and above their day 0 results for the study period; similarly, at each time interval, results tended to be better compared to the previous test. The tenodesis screw group exhibited significantly higher failure loads at week 3 (419 ± 53 N) compared to day 0 values (164 ± 45 N) (P=. 009). The same level of significance was observed at week 6 in the remaining 2 groups. Conclusion Tenodesis of the biceps tendon on the proximal humerus at an extra-articular site does not weaken after surgery. The tenodesis screw group had a significantly higher increase in the fixation strength within the first 3 weeks. Clinical Relevance No significant differences could be found between the failure loads of all 3 investigated tenodeses for the first 9 weeks.

Effects of lipopolysaccharide on the radiation-induced changes in the blood-brain barrier and the astrocytes.

The use of radiation to improve the efficacy of chemotherapy on malignant brain tumors is also known to cause side effects on vascular endothelial cells and astrocytes in normal parts of the brain. We investigated the effects of lipopolysaccharide (LPS) on the functional and structural properties of blood-brain barrier (BBB) and the activity of astrocytes during whole-brain irradiation in rats. The permeability of the BBB to Evans blue (EB) dye significantly increased in the cerebral cortex, diencephalon and cerebellum regions of rats exposed to irradiation (P<0.01). In contrast, the BBB permeability in irradiated rats was significantly reduced by LPS (P<0.05). Tumor necrosis factor-alpha (TNF-alpha) levels were increased following LPS, irradiation and irradiation plus LPS (P<0.05, P<0.01). Irradiated brain vessels showed a considerable loss of staining intensity of tight junction proteins Zonula occludens-1 (ZO-1) and occludin. Staining for Zonula occludens-1 and occludin was intensive in animals treated with LPS and irradiation plus LPS. Glial fibrillary acidic protein (GFAP) immunoreactivity was seen in very few astrocytes of irradiated brains. However, this staining showed an increased positive intensity in the brain sections of LPS-treated as well as of irradiation plus LPS-treated animals. These results indicate that LPS reduces the passage of exogenous vascular tracer EB-binding albumin into the brain, at least partly, by increasing the expression of tight junction proteins and GFAP, following the irradiation. We suggest that irradiation may affect paracellular permeability through disruption of tight junction proteins, Zonula occludens-1 and occludin, and LPS could provide beneficial effects on the BBB integrity and the astrocytes against irradiation damage.

Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1.

We report 4 cases of malignant peripheral nerve sheath tumors (MPNST) with neurofibromatosis type 1 (NF1). Mean age was 29.5. Two of them had a family history. Three of them were male. All of them had enlarging mass and pain in the background of neurofibromas. Locations were popliteal, thigh and forearm. The masses were greater than 5 cm in diameter in each case. In two cases the mass was showing continuity with a nerve. One patient had a nonossifying fibroma as well as a MPNST. Wide excision and radiotherapy were applied to three of the patients. One of them did not take any therapy after surgical resection. Two of the patients died of lung metastases after a mean period of 12.5 months. In a majority of NF1 patients MPNST emerges from a preexisting neurofibroma. The patients with NF1 are at greatest risk for developing sarcomas, so they should be followed closely.

Synovial sarcoma: a rare tumor of larynx.

Synovial sarcoma is a soft tissue sarcoma of unknown histogenesis and occurs predominantly in the lower extremities of young adults. The head and neck is a relative rare location. There are about 10 cases with laryngeal localization in the literature. We present a 24 year-old male with an endolaryngeal mass. Incisional biopsy and the hemilaryngectomy material revealed a biphasic synovial sarcoma. One year later a local recurrence occurred. Tumor excision and neck dissection were performed. Radiotherapy was added. Six months later lung metastases was discovered on thoracic CT. The patient received chemotherapy for 6 courses. The metastases responded well to chemotherapy and the patient is now alive without tumor on radiological and clinical examination after 3.5 years of follow-up.

Influence of Hypercholesterolemia and Hypertension on the Integrity of the Blood–Brain Barrier in Rats

Hypercholesterolemia and/or hypertension impair endothelial function in peripheral vasculature; however, their impact on endothelial cells of brain microvessels is unclear. We investigated the effects of hypercholesterolemia on the integrity of the blood–brain barrier (BBB) and the activity of astrocytes during Nω-nitro-L-arginine methyl ester (L-NAME) hypertension followed by angiotensin (ANG) II. We found significant decreases in superoxide dismutase levels with all treatments except ANG II and L-NAME plus ANG II, and in catalase concentrations except ANG II and cholesterol plus L-NAME. Nitric oxide (NO) concentrations were significantly decreased by L-NAME but significantly increased by cholesterol. L-NAME-stimulated plasma malondialdehyde (MDA), Ox-LDL, and cholesterol levels were significantly augmented by cholesterol. Glutathione (GSH) levels significantly decreased, while MDA, TNF-α, and Ox-LDL levels significantly increased in cholesterol and/or L-NAME. The increase in BBB permeability by acute hypertension in hypercholesterolemic hypertensive animals was less than that observed in chronically hypertensive animals. Brain vessels of L-NAME-treated animals showed a considerable loss of immunoreactivity for tight junction proteins, occludin, and ZO-1. Immunoreactivity for occludin and ZO-1 increased in cholesterol plus L-NAME and decreased in cholesterol. Glial fibrillary acidic protein (GFAP) immunoreactivity was seen in few astrocytes in the brain sections of L-NAME-treated animals, but increased in cholesterol plus L-NAME. Positive immunoreactivity for vascular endothelial growth factor (VEGF) was observed in cholesterol and cholesterol plus L-NAME plus ANG II. We suggest that hypercholesterolemia may affect BBB integrity through increasing the expression of tight junction proteins and GFAP and leading to the production of VEGF, at least partly, via increased NO, TNF-α, and catalase in hypertensive conditions.

Effects of atorvastatin on blood-brain barrier permeability during L-NAME hypertension followed by angiotensin-II in rats.

Recent studies suggest that 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, can have direct effects on blood vessels beyond their cholesterol-lowering effects. We investigated the effects of atorvastatin on the functional and structural properties of blood-brain barrier (BBB) and the activity of astrocytes during the N(omega)-nitro-L-arginine methyl ester (L-NAME) hypertension followed by angiotensin (ANG) II. We found that decreases in concentration of serum catalase and plasma nitric oxide (NO) induced by L-NAME were significantly ameliorated by atorvastatin, whereas L-NAME-induced serum malondialdehyde and cholesterol concentration increases were significantly reduced by atorvastatin. The content of Evans blue (EB) dye significantly increased in cerebellum, left cerebral cortex and diencephalon regions but atorvastatin markedly reduced the increased BBB permeability to EB in the brain regions of animals treated with L-NAME and L-NAME plus ANG II. Brain vessels of L-NAME-treated animals showed a considerable loss of immunoreactivity of tight junction proteins, zonula occludens (ZO)-1 and occludin. Immunoreactivity for ZO-1 and occludin increased in animals treated with atorvastatin and L-NAME plus atorvastatin. Glial fibrillary acidic protein (GFAP) immunoreactivity was seen in few astrocytes in the brain sections of L-NAME, but immunoreactivity for GFAP increased in L-NAME plus atorvastatin-treated animals. We suggest that long-term L-NAME treatment may affect BBB permeability through disruption of tight junction proteins, at least partly, via decreased NO concentration and increased oxidant capacity; the improvement of BBB integrity and astrocytic activity would be more closely associated with the action of atorvastatin favoring the increase in anti-oxidant capacity and expression of tight junction proteins and GFAP.

Morphological and functional changes of blood–brain barrier in kindled rats with cortical dysplasia

Cortical dysplasia (CD) is one of the major causes contributing to epileptogenesis associated with blood-brain-barrier (BBB) disturbances. The current study investigated the functional and ultrastructural changes of BBB in pentylenetetrazole (PTZ)-kindled rats with CD. Pregnant rats on E17 were exposed to 145 cGy of gamma-irradiation and offspring were used for experiments. The rats were given PTZ three times per week to induce kindling. The permeability of BBB was determined by using sodium fluorescein (NaFlu). Immunohistochemistry for occludin, GFAP and c-fos, western-blot analysis for occludin and electron microscopy for the ultrastructural alterations in BBB were performed. The brain level of NaFlu did not increase in rats with CD and/or kindling. Following administration of a convulsive dose of PTZ, a significant increase in BBB permeability was observed in kindled rats with CD. Occludin immunoreactivity and expression remained essentially unchanged in all groups. Slightly enhanced immunoreactivity for GFAP was observed in all groups except control. c-fos immunoreactivity in brain sections of kindled rats with CD displayed a striking increase by convulsive PTZ challenge. Tight junctions were ultrastructurally intact, whereas markedly increased number of pinocytotic vesicles was noted in brain endothelium of kindled rats with CD by convulsive dose of PTZ. The present study showed that epileptic seizures induced by convulsive PTZ challenge during kindling-mediated epileptogenesis in the presence of CD changed both functional and ultrastructural properties of the BBB and considerably enhanced transendothelial vesicular transport, while paracellular pathway was apparently not involved in this setting.

The effect of transforming growth factor β1 (TGF-β1) on the regenerate bone in distraction osteogenesis

Distraction osteogenesis is a well established clinical treatment for limb length dicrepancy and skeletal deformities. Transforming growth factor beta 1 (TGF-β1) is a multifunctional peptide which controls proliferation and expression of cells specific to bone like chondrocytes, osteoblasts, osteoclasts including mesenchymal precursor cells. To decrease the external fixation time with increasing the strength of regenerate (newly formed bone after distraction) we tested the effect of locally applied transforming growth factor beta 1 on distraction osteogenesis. A total of 28 mature female white New zealand rabbits weighing 3,5 kg–4,5 kg were studied. 10 animals were belonging to biomechanical testing group (5 for the study and 5 for the control subgroups), and the others were to histology group. In biomechanical group after tibial ostetomy TGF-β1 was applied subperiosteally for 5 days just proximal to osteotomy site. Control group received only the solvent. Seven days after tibial osteotomy distraction was started at a rate of 0.25mm/12 hours for 3 weeks with a unilateral fixator. Rabbits were sacrified at the end of a consodilation period 8 week after tibial osteotomy. We assessed density of the elongation zone of rabbit tibial bones with the computed tomography. Then biomechanical parametres were assessed using the torsional testing using the material testing machine. In histology group rabbits were classified as control and study (rabbits that were given TGF-β1). Rabbits were sacrified at the end of first week, second week and fourth week also at the end of consolidation period 8 week after tibial osteotomy. Immunohistochemical and histologic parameters were examined. Biomechanical testing was applied as tortional testing. These values are used in determination of maximal loading, stiffness and energy absorbed during testing (brittlenes). The histomorphometric examination looked for the differences between the study and control groups in terms of bone formation pattern, bone quality and quantity. The immunohistochemical studies investigated the mechanism of TGF- β1, and its presence in different cell types. The results of this study suggest that locally applied TGF-β1 improves the mineral density of distraction gap and load to failure(energy absorbed during testing). Though there is no significant histomorphometric difference between the study and control groups, there is an increased bone mineral density and an according maximum energy absorbance in the study group. This effect can be explained by the following mechanism: TGF-β1 exerts its effect on two different receptor types (Type 1 and 2). Type 1 receptors are localized to bone matrix and type 2 receptors are localized to the intracellular space. The specific stains utilized in the current experiment are specific to type 2 receptors. They have been shown to be down-regulated by exogenous TGF-β1 injections. Most probably, type 1 receptors are up-regulated by this exogenous administration, but unfortunately, there is currently no specific stain on tha market to display type 1 receptors and to prove this explanation.

Prognostic factors and survival in late adolescent and adult patients with small round cell tumors

The primary objective of this study is to review the clinical characteristics of 25 patients in the adult and late adolescent age group, diagnosed and treated with small round cell tumors involving soft tissues (extraosseous Ewing sarcoma, rhabdo-myosarcoma, primitive neuroectodermal tumor, and undiffer-entiated small round cell tumors). Additionally, survival and prognostic factors influencing the outcome with multimodality treatment are evaluated. There were 19 males (76%) and 6 females (24%). The median age was 26 years (range: 15-56 years). In 9 patients (36%), the tumor was located at an extremity, whereas 16 patients (64%) had central localizations. Tumor size was larger than 10 cm in 7 patients (29.2%). Six patients (24%) had metastatic disease. Twelve patients (48%) received radiation and 16 patients (64%) underwent surgery. Among the resected tumors, 2 were resected with contaminated margins (12.5%), whereas 2 were radically resected and 12 (75%) were resected with wide margins. All patients were given a median of 4 cycles of multiagent chemotherapy (1–14 cycles). With preoperative chemotherapy, complete regression (CR) of the tumor was achieved in 6 patients (24%). In 4 patients (16%), a partial response was obtained. After the completion of multimodality treatment, 12 patients (48%) had a CR. Progression-free (PFS) and overall survival (OS) for the entire group was 25.0 ± 10.8% at 1 year and 30.5 ± 15.5% at 3 years, respectively. Nonmetastatic disease, wide and radical resection, and presence of CR to multimodality treatment were associated with a significantly longer PFS and OS by univariate analysis. By multivariate analysis, CR to multimodality treat-ment was the only independent predictive factor for a longer OS (p: 0.0036, relative risk [RR]: 23.6, 95% CI: 2.8; 198.7) and metastatic presentation was the only independent factor predic-tive for a shorter PFS (p: 0.017, RR. 15, 95% CI: 1.6; 141.2). Large-scale, multicenter studies are required for a better eval-uation of the nonpediatric age group with small round cell tumors.

Levetiracetam decreases the seizure activity and blood-brain barrier permeability in pentylenetetrazole-kindled rats with cortical dysplasia

This study investigates the effects of levetiracetam (LEV) on the functional and structural properties of blood-brain barrier (BBB) in pentylenetetrazole (PTZ)-kindled rats with cortical dysplasia (CD). Pregnant rats were exposed to 145 cGy of gamma-irradiation on embryonic day 17. In offsprings, kindling was induced by giving subconvulsive doses of PTZ three times per week for 45 days. While all kindled rats with CD died during epileptic seizures evoked by the administration of a convulsive dose of PTZ in 15 to 25 min, one week LEV (80 mg/kg) pretreatment decreased the mortality to 38% in the same setting. LEV caused a remarkable decrease (p<0.01) in extravasation of sodium fluorescein dye into the brain tissue of kindled animals with CD treated with convulsive dose of PTZ. Occludin immunoreactivity and expression remained essentially unchanged in all groups. Immunoreactivity for glial fibrillary acidic protein (GFAP) was observed to be slightly increased by acute convulsive challenge in kindled rats with CD while LEV pretreatment led to GFAP immunoreactivity comparable to that of controls. An increased c-fos immunoreactivity in kindled rats with CD exposed to convulsive PTZ challenge was also observed with LEV pretreatment. Tight junctions were ultrastructurally intact, whereas LEV decreased the increased pinocytotic activity in brain endothelium of kindled rats with CD treated with convulsive dose of PTZ. The present study showed that LEV decreased the increased BBB permeability considerably by diminishing vesicular transport in epileptic seizures induced by convulsive PTZ challenge in kindled animals with CD.