Increased Facet Fluid Predicts Dynamic Changes in the Dural Sac Size on Axial-Loaded MRI in Patients with Lumbar Spinal Canal Stenosis.

BACKGROUND AND PURPOSE: Axial-loaded MR imaging, which simulates the spinal canal in a standing position, demonstrates reductions of the dural sac cross-sectional area in patients with lumbar spinal canal stenosis. However, there has been no useful conventional MR imaging finding for predicting a reduction in the dural sac cross-sectional area on axial-loaded MR imaging. Previous studies have shown that increased facet fluid is associated with the spinal instability detected during positional changes. The purpose of this study was to analyze the correlations between facet fluid and dynamic changes in the dural sac cross-sectional area on axial-loaded MR imaging. MATERIALS AND METHODS: In 93 patients with lumbar spinal canal stenosis, the dural sac cross-sectional area was measured by using axial images of conventional and axial-loaded MR imaging. Changes in the dural sac cross-sectional area induced by axial loading were calculated. The correlation between the facet fluid width measured on conventional MR imaging and the change in dural sac cross-sectional area was analyzed. The change in the dural sac cross-sectional area was compared between the intervertebral levels with and without the facet fluid width that was over the cutoff value determined in this study. RESULTS: The dural sac cross-sectional area was significantly smaller on axial-loaded MR imaging than on conventional MR imaging. The facet fluid width significantly correlated with the change in the dural sac cross-sectional area (r = 0.73, P < .001). The change in the dural sac cross-sectional area at the intervertebral level with the facet fluid width over the cutoff value was significantly greater than that at the other level. CONCLUSIONS: The increased facet fluid on conventional MR imaging is highly predictive of the dynamic reduction of dural sac cross-sectional area detected on axial-loaded MR imaging in the clinical assessment of lumbar spinal canal stenosis.

Dynamic changes in the dural sac cross-sectional area on axial loaded MR imaging: is there a difference between degenerative spondylolisthesis and spinal stenosis?

BACKGROUND AND PURPOSE: Axial loaded MR imaging, which can simulate the spinal canal of patients in a standing position, demonstrates a significant reduction of the DCSA compared with conventional MR imaging and provides valuable imaging findings in the assessment of the lumbar spinal canal. The purpose of this study was to compare the DCSA on axial loaded MR imaging between patients with DS and SpS. MATERIALS AND METHODS: Eighty-eight consecutive patients were divided into DS and SpS groups. DCSA on conventional MR imaging and axial loaded MR imaging and changes in the DCSA induced by axial loading were compared between DS and SpS groups. The prevalence of a significant change (>15 mm(2)) in the DCSA was compared between the 2 groups. RESULTS: Axial loaded MR imaging demonstrated significantly smaller DCSA in the DS group (35 ± 22 mm(2)) than in the SpS group (50 ± 31 mm(2)), though conventional MR imaging did not show any differences between the 2 groups. The change in the DCSA induced by axial loading was significantly larger in the DS group (17 ± 12 mm(2)) compared with the SpS group (8 ± 8 mm(2)). The prevalence of a >15-mm(2) change in the DCSA was significantly higher in the DS group (62.5%) than in the SpS group (16.7%) (odds ratio, 8.33; 95% confidence interval, 3.09-22.50). CONCLUSIONS: Axial loaded MR imaging demonstrated significantly larger changes in the DCSA in patients with DS compared those with SpS. A significant change in the DCSA was more frequently observed in patients with DS. Axial loaded MR imaging may therefore be a more useful tool to decrease the risk of underestimating the spinal canal narrowing in patients with DS than in those with SpS.

Clinical significance of intramedullary Gd-DTPA enhancement in cervical myelopathy.

STUDY DESIGN: Prospective multicenter study. OBJECTIVE: To clarify the significance of intramedullary Gd-DTPA enhancement in cervical myelopathy, the prevalence, morphologic features, clinical relevance and postoperative change were investigated. SETTING: Four hospitals in Japan. METHODS: A total of 683 patients with cervical myelopathy who underwent decompressive surgery were consecutively examined. T1, 2 and Gd-DTPA-enhanced MRI were taken before surgery. Fifty consecutive cases without intramedullary enhancement were allocated in the non-enhancement group. The following variables were investigated: prevalence of the enhancement, the morphologic feature, the relationship between the enhancement and T2 high-intensity areas, the change of the Japanese Orthopedic Association (JOA) score for cervical myelopathy and the change of the enhancement after surgery. RESULTS: Intramedullary enhancement was observed in 50 cases (7.3%). The enhancements were observed between the most severely compressed disc and the cranial half of the lower vertebral body. On axial images, they were observed at the posterior or posterolateral periphery of the spinal cord. Enhancement areas were observed within T2 high-intensity areas and smaller than them. The preoperative JOA score was 9.8+/-2.8 points in the enhancement group and 9.8+/-3.3 points in the non-enhancement group (NS). The postoperative JOA score was 12.7+/-2.9 points in the enhancement group and 14.2+/-2.4 in the non-enhancement group (P=0.006). Intramedullary enhancement disappeared in 60% of the patients 1 year after surgery. CONCLUSION: Intramedullary enhancement indicated not the severity of preoperative symptoms, but a sign of a worse prognosis.

Structure-activity relationship of ghrelin: pharmacological study of ghrelin peptides.

Ghrelin, a novel peptide purified from the stomach, is the endogenous ligand of the growth hormone secretagogue receptor. The Ser(3) residue of ghrelin is modified with a lipid n-octanoic acid, a modification necessary for hormonal activity. To clarify the role of acyl modification and to identify the active core of ghrelin, we examined the activities of partially digested ghrelin and synthetic ghrelin derivatives. The activities confirmed that the N-terminal portion is the active core. Moreover, synthetic ghrelin derivatives demonstrated that octanoic acid is not the only modification of the Ser(3) side chain to sustain the activity of ghrelin; other acyl acid modifications maintained activity. Amino acid replacement of Ser(3) indicated that an L-configuration of the third residue is critical for ghrelin activity. In addition, more stable ether or thioether bonds are capable of replacing the octanoyl ester bond in ghrelin, advantageous for the generation of pharmaceuticals with longer stability.

Papillary carcinoma of the thymus: report of four cases of a new microscopic type of thymic carcinoma.

We describe four cases of papillary carcinoma arising in the thymus. Three showed low-grade atypia and were associated with spindle cell-type thymoma. The fourth case showed high-grade atypia and had no evidence of an association with thymoma. Two of three low-grade cases invaded the lung and showed extensive lymphatic permeation. Cyst formation was seen in one case. Immunohistochemically, the tumor cells were positive for carcinoembryonic antigen (CEA), Leu-M1, Ber-EP4, calretinin (2 cases), and CD5 and were negative for thyroglobulin and pulmonary surfactant apoprotein. Ultrastructural findings for the one case studied by electron microscopy gave evidence against a mesothelial origin of the tumor. The histologic similarities and the intimate association with spindle cell thymoma indicate that papillary thymic carcinoma may arise from the papillotubular formations sometimes seen in the former tumor. Papillary thymic carcinoma, a lesion hitherto undescribed, should be considered in the differential diagnosis of anterior mediastinal tumors. Conceivably, it may be the source of some metastatic papillary carcinomas with or without psammoma bodies in cervical lymph nodes, in which no tumor is found in the thyroid gland.

A pertussis toxin-sensitive GTP-binding protein plays a role in the G0-G1 transition of rat hepatocytes following establishment in primary culture.

Acute spontaneous c-myc gene expression and sustained increase of a GTP-binding protein(s) (G-protein) which is sensitive to islet-activating protein (IAP), pertussis toxin, occurred early during primary culture of adult rat hepatocytes. Following these earlier events, DNA synthesis was demonstrated in response to EGF and insulin. Addition of IAP immediately after plating of primary cultures inhibited c-myc expression and the hormone-induced DNA synthesis. Addition at 24 h or later following cell inoculation, however, produced only weak effects on DNA synthesis, even though the IAP-sensitive G-proteins were completely inactivated. We conclude that the IAP-sensitive G-protein(s) plays a role in the earlier process(es) of the G0-G1 transition, which is essential for the initiation of growth factor-dependent DNA synthesis.