Topography of the human corpus callosum using diffusion tensor tractography

OBJECTIVE: To evaluate the crossing fiber trajectory through the corpus callosum using distortion-corrected diffusion tensor tractography in the human brain. METHODS: After correcting distortion associated with large-diffusion gradients, T2-weighted echo planar images (EPIs) acquired from 10 right-handed healthy men were coregistered into T2-weighted fast spin echo images using linear through sixth-order nonlinear, 3-dimensional, polynomial warping functions. The optimal transformation parameters were also applied to the distortion-corrected diffusion-weighted EPIs. Diffusion tensor tractography through the corpus callosum was reconstructed, employing the "1 or 2 regions of interest" method. RESULTS: Compared with the lines through the genu, those through the rostrum ran more inferiorly and seemed to enter the orbital gyrus. Those lines entering posterior temporal white matter (tapetum) crossed through the ventral portion of the splenium and were clearly distinguished from lines that reached parieto-occipital white matter (forceps major). CONCLUSION: Diffusion tensor tractography is a feasible noninvasive tool to evaluate commissural fiber trajectory.     

Thoracoabdominal aortic aneurysm repair after detection of the Adamkiewicz artery by magnetic resonance angiography; a way to shorten operating time and improve outcome

Surgical results were compared between 18 patients (group A) who underwent preoperative anatomic characterization of the Adamkiewicz artery by magnetic resonance angiography (MRA) and 38 patients (group B) without such imaging. In group A, intercostal or lumbar arteries related to the aneurysm were reattached to the graft only when they represented the origin of the Adamkiewicz artery. In group B, reconstruction from the Th 7 intercostal and the L2 lumbar arteries was performed whenever possible. In-hospital mortality was 16.7% in group A and 15.8% in group B. Total aortic clamp time and operating time were only 84 and 437 min in group A, compared with 134 and 589 min in group B. Three patients showed postoperative paraplegia in group B. No spinal cord injury occurred in patients whose artery had been detected preoperatively. Preoperative anatomic delineation of the Adamkiewicz artery by MRA can reduce risk of ischemic injury to the spinal cord and decrease operating time required for repair of thoracoabdominal aortic aneurysms.     

Prognostic factors for myasthenic crisis after transsternal thymectomy in patients with myasthenia gravis

OBJECTIVE: The purpose of this study was to assess which clinical features of patients with myasthenia gravis predict postoperative respiratory problems due to myasthenic crisis after transsternal thymectomy. METHODS: One hundred twenty-two patients who underwent transsternal thymectomy in our institute were analyzed retrospectively. Fourteen of those experienced myasthenic crisis and required prolonged (48 hours or more) postoperative mechanical ventilation. The following factors were evaluated: sex, age, body mass index, grade of symptom, disease interval, existence of thymoma, history of preoperative crisis, doses of anticholinesterase drugs, steroid use, pulmonary function, serum anti-acetylcholine receptor antibody, history of pulmonary disease, presence of other disease, operation time, and blood loss. RESULTS: Univariate analysis revealed preoperative bulbar symptoms (odds ratio = 14.246, P =.001), history of preoperative myasthenic crisis (7.091,.018), and preoperative serum level of anti-acetylcholine receptor antibody > 100 nmol/L (4.098,.044) were prognostic factors for postoperative myasthenic crisis. On the other hand, multivariate logistic regression analysis revealed preoperative bulbar symptoms (33.333,.004), preoperative serum level of anti-acetylcholine receptor antibody > 100 nmol/L (7.874,.020), and intraoperative blood loss > 1000 mL (18.519,.048) were prognostic factors for postoperative myasthenic crisis. CONCLUSIONS: In this study, postoperative myasthenic crisis after transsternal thymectomy in 122 patients with myasthenia gravis was affected by the existence of preoperative bulbar symptoms, history of preoperative myasthenic crisis, preoperative serum level of anti-acetylcholine receptor antibody > 100 nmol/L, and intraoperative blood loss > 1000 mL. Meticulous preoperative and postoperative care should be carried out to prevent postoperative myasthenic crisis in patients with these prognostic factors.     

"Anoikis" of oligodendrocytes induced by Wallerian degeneration: ultrastructural observations

Oligodendrocytes undergo apoptosis in the white matter tracts remote from the experimental cord injury, although its significance is not understood. Our ultrastructural study, however, enabled us to speculate on its neurobiological implications. The spinal cords of male Wistar rats (4 week-old) were transected at Th11 level. At 4, 5, and 7 days after surgery the animals were transcardially perfusion-fixed. The removed cord was embedded in epoxy resin and examined by electron microscopy. Post-embedding terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end labeling (TUNEL) method was also performed. In the degenerative dorsal column above the transection, profiles of apoptotic oligodendrocytes were always found, embedded in a space formed by dilated degenerative myelin lamellae. Often, the dilated space in the myelin sheath lacked any apparent background proteinaceous matrix. In the electron microscopic TUNEL method, these apoptotic cells were electron dense in accordance with nuclear heterochromatinization. In conclusion, in the process of Wallerian degeneration, we observed the apoptosis of oligodendrocytes in a space formed by the split myelin sheath. These degenerative cells, which were enclosed in an ultrafiltrate-filled space formed by split myelin lamellae, were reminiscent of "anoikis."     

Direct-Vision Retrosternal Dissection Using the Kent Retractor for Sternal Re-Entry

Repeat median sternotomy is still associated with high morbidity and mortality from catastrophic hemorrhage or myocardial injury. To overcome these problems, we devised a new technique of sternal re-entry using the Kent retractor set (Takasago Ika Kogyo, Tokyo, Japan), which increases the safety of retrosternal dissection and sternal redivision.     

Concomitant Mitral and Tricuspid Valve Infective Endocarditis: Report of a Case

A rare case of native valve endocarditis affecting both the normal mitral and tricuspid valves is presented. A 25-year-old woman with an acute ischemic stroke was found to have vegetation secondary to infective endocarditis as the embolic source. One month after the onset of embolic cerebrovascular intervention, a valve repair with the implantation of artificial chordae, sliding commissuroplasty, and ring annuloplasty resulted in a complete recovery.     

Cytokines modulate cilomilast response in lung fibroblasts

Fibroblasts, as a major source of extracellular interstitial connective tissue matrix, play an important role in wound healing and the development of fibrosis. The phosphodiesterase (PDE) 4 inhibitor cilomilast inhibits fibroblast chemotaxis and fibroblast-mediated gel contraction. Using the Boyden blindwell chamber chemotaxis assay and the type I collagen gel contraction model, this study investigated whether specific cytokines modulate cilomilast's inhibitory effect through regulation of endogenous PGE(2) production. Human recombinant IL-1beta stimulated PGE(2) production and shifted the cilomilast concentration-dependence curve to the left in both assay systems, indicating increased sensitivity to cilomilast. In contrast, human recombinant IL-4 inhibited PGE(2) production and shifted the cilomilast concentration-dependence curve to the right in both systems. In summary, the inhibitory effect of cilomilast on fibroblast migration and collagen gel contraction is modulated by IL-1beta and IL-4 through regulation of PGE(2) production.     

The effects of monobromobimane on neuronal cell death in the hippocampus after transient global cerebral ischemia in rats

Calcium accumulation and free radical formation in the mitochondria are suggested to result in opening of the mitochondrial permeability transition pore that may be an initial step in neuronal cell death. The purpose of the present study was to determine whether monobromobimane (MBM) was a possible protective agent against neuronal cell death after transient global ischemia and the swelling of isolated hippocampal mitochondria. Infusion of MBM (1 or 3 microg) to cerebral ventricles 30 min before ischemia attenuated the expression of TUNEL-labeled cells and neuronal cell death in the hippocampal CA1 region at 72 h of reperfusion dose-dependently. Treatment with MBM inhibited an increase in caspase-3-like activity at 48 h of reperfusion in the hippocampus. MBM (30-300 microM) also inhibited an enhanced swelling rate induced by Ca2+ and phenylarsineoxide in the isolated hippocampal mitochondria. These results suggest that in vivo treatment with MBM may protect against neuronal cell death through inhibition of the mitochondrial swelling and caspase-3-dependent apoptotic pathway.     

Splicing profile based protein categorization between human and mouse genomes by use of the DDBJ Web services

In one scenario of gene evolution, exon shuffling plays a fundamental role in increasing gene diversity. This paper is an appraisal of the biological relevance of categorising proteins by their splicing profiles (exon-intron structures). The central question is whether protein function is more correlated with splicing profiles than sequence similarity, or not. To approach this question, a splicing profile similarity (SPS) index, which measures relative exon length discrepancy, was devised. Arbitrary human proteins were compared, in terms of SPS and amino acid sequence similarity, to their 1) mouse orthologues and 2) human paralogues, which epitomise functional equivalence and non-equivalence, respectively, to methodically elucidate the global relationship between a) biological function, b) splicing profile similarity, and c) sequence similarity. Protein function is more correlated with splicing profile similarity than sequence similarity as demonstrated by the fact that human-mouse orthologues (HMOs) display significantly higher splicing profile similarity than do human-human paralogues (HHPs), despite the mutual sequence similarity between these two categories. This finding indicates that splicing profile-based protein categorisation is biologically meaningful.