Video-assisted thoracoscopic surgery versus open thoracotomy for anterior thoracic spinal fusion. A comparative radiographic, biomechanical, and histologic analysis in a sheep model

STUDY DESIGN: In this in vivo investigation, a sheep model was used to compare the efficacy of a video-assisted thoracoscopic approach and a traditional thoracotomy in promoting a successful interbody spinal arthrodesis. OBJECTIVES: To compare the incidence of successful anterior spinal arthrodesis among three stabilization techniques-iliac crest, Bagby and Kuslich device, and Z-plate--performed using a video-assisted thoracoscopic approach and conventional open thoracotomy approaches. SUMMARY OF BACKGROUND DATA: A clinical outcome study on open versus endoscopic spinal fusion is not yet available. Moreover, no basic scientific investigations have been conducted to determine whether the success of an endoscopic arthrodesis is comparable to that of a conventional open procedure. METHODS: Fourteen Western Crossbred sheep underwent three identical destabilization procedures at T5-T6, T7-T8, and T9-T10, in which the anterior and middle osteoligamentous columns of the spine were resected, followed by three randomized reconstruction procedures using iliac autograft alone, and Z-plate stabilization with iliac autograft. In seven sheep, the entire destabilization-reconstruction procedure was performed using a video-assisted thoracoscopic surgical approach. In the remaining seven, the procedure was performed by conventional open thoracotomy. RESULTS: Histomorphometric and biomechanical evaluation demonstrated that the video-assisted thoracoscopic approach and open thoracotomy arthrodesis had comparable bone formation and biomechanical properties (P > 0.05). However, the Z-plate fusions, as a group, demonstrated increased flexion-extension stiffness properties and trabecular bone formation compared with the autograft and Bagby and Kuslich device fusions (P < 0.05). CONCLUSIONS: Thoracic interbody spinal fusions performed by thoracoscopy have demonstrated histologic, biomechanical, and radiographic equivalence to those performed by a thoracotomy approach. However, in the endoscopy group, intraoperative complications causing longer operative times, higher estimated blood loss, and increased animal morbidity indicated a substantial learning curve associated with the adoption of this surgical technique.     

Neck and total body fat deposition in nonobese and obese patients with sleep apnea compared with that in control subjects

Recent animal and human studies have suggested that leptin secretion is closely linked to the functions of the hypothalamic-pituitary-adrenal (HPA) axis and the immune system, both of which are crucial in influencing the course and outcome of critical illness. Therefore, we measured basal plasma leptin levels and examined the circadian secretion of leptin, in parallel with the hormones of the HPA axis and a key cytokine, interleukin-6, in critically ill patients with acute sepsis. Sixteen critically ill patients from the University of Leipzig Intensive Care Unit were recruited for this study. All of these patients fulfilled the standard diagnostic criteria for sepsis. Plasma leptin levels were measured in all patients and controls at 09:00. In addition, in a subgroup of eight critically ill patients and all of the nine controls plasma leptin, cortisol, ACTH and interleukin-6 concentrations were measured every 4 hours for 24 hours. Mean plasma leptin levels were three-fold higher (18.9 +/- 4.5 ng/ml) in critically ill patients than controls (3.8 +/- 1.0 ng/ml, p < 0.05). Similarly, ACTH levels were lower (7.8 +/- 3.4 pmol/l) in patients than in controls (17.1 +/- 1.5 pmol/l, p < .001), while plasma cortisol levels were increased (947.6 +/- 144 nmol/l) in patients compared to controls (361.1 +/- 29, p < 0.001). Morning plasma interleukin-6 levels were markedly elevated in all patients with sepsis (1238.0 +/- 543.1 pg/ml) versus controls (6.4 +/- 1.7, p < 0.001). The controls exhibited a nyctohemeral fluctuation in plasma leptin levels with peak levels at 23:00; in contrast, septic patients, had no nocturnal rise of leptin. In healthy controls, plasma leptin and cortisol had reciprocal circadian rhythms with high nocturnal leptin levels and low nocturnal cortisol concentrations; in critically ill patients, this relation was abolished. Mean leptin levels were three-fold higher in patients who survived the septic episode (25.5 +/- 6.2, n = 10) than in non-survivors (8.0 +/- 3.7, n = 6, p < 0.01). We conclude that in addition to its function as an anti-obesity factor, leptin may play a role in a severe stress state such as acute sepsis.     

'Musical brain' revealed by high-field (3 Tesla) functional MRI

The cortical areas subserving music literacy were investigated using high-field (3 Tesla) functional magnetic resonance imaging (fMRI). The activation pattern associated specifically with music score reading was compared with that associated with reading text in a subject's primary and secondary language. While the areas of activation were predominantly identical for all three reading modalities, there were areas within the occipital cortex activated exclusively by music score reading. Grand analysis of the activation patterns of eight pianists unequivocally identified that the principal cortical area needed for music literacy is the cortex flanking the right transverse occipital sulcus (musical brain).     

Analytic–Numerical Solution of Contact Problems of Thermoelasticity for Thermosensitive Bodies

We propose a method for the construction of analytic–numerical solutions of nonstationary problems of heat conduction for the case of contact of thermosensitive bodies of simple shape (flat, cylindrical, or spherical) with heat exchange with the ambient medium through the surfaces of the bodies. It is assumed that the thermal diffusivity is constant. We construct the solution of a nonstationary problem of heat conduction for a system formed by a cylindrical body with thin coating heated by the ambient medium in the process of convective heat exchange through the surface of the coating. The thermal contact between the cylinder and the coating is regarded as perfect. The solution of the corresponding quasistatic problem of thermoelasticity is constructed by the perturbation method. The numerical analysis of the results is performed.     

Late-onset chronic inflammatory encephalopathy in immune-competent and severe combined immune-deficient (SCID) mice with astrocyte-targeted expression of tumor necrosis factor

To examine the role of tumor necrosis factor (TNF)-alpha in the pathogenesis of degenerative disorders of the central nervous system (CNS), transgenic mice were developed in which expression of murine TNF-alpha was targeted to astrocytes using a glial fibrillary acidic protein (GFAP)-TNF-alpha fusion gene. In two independent GFAP-TNFalpha transgenic lines (termed GT-8 or GT-2) adult (>4 months of age) animals developed a progressive ataxia (GT-8) or total paralysis affecting the lower body (GT-2). Symptomatic mice had prominent meningoencephalitis (GT-8) or encephalomyelitis (GT-2) in which large numbers of B cells and CD4+ and CD8+ T cells accumulated at predominantly perivascular sites. The majority of these lymphocytes displayed a memory cell phenotype (CD44high, CD62Llow, CD25-) and expressed an early activation marker (CD69). Parenchymal lesions contained mostly CD45+ high, MHC class II+, and Mac-1+ cells of the macrophage microglial lineage with lower numbers of neutrophils and few CD4+ and CD8+ T cells. Cerebral expression of the cellular adhesion molecules ICAM-1, VCAM-1, and MAdCAM as well as a number of alpha- and beta-chemokines was induced or upregulated and preceded the development of inflammation, suggesting an important signaling role for these molecules in the CNS leukocyte migration. Degenerative changes in the CNS of the GFAP-TNFalpha mice paralleled the development of the inflammatory lesions and included primary and secondary demyelination and neurodegeneration. Disease exacerbation with more extensive inflammatory lesions that contained activated cells of the macrophage/microglial lineage occurred in GFAP-TNFalpha mice with severe combined immune deficiency. Thus, persistent astrocyte expression of murine TNF-alpha in the CNS induces a late-onset chronic inflammatory encephalopathy in which macrophage/microglial cells but not lymphocytes play a central role in mediating injury.