Superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging has been used for the detection of hepatic tumors. However, little is known about this technique in relation to hepatocellular carcinoma (HCC).The aim of this study was to investigate whether SPIOenhanced MR imaging can be useful in assessing histological grades of HCC. The authors studied histologically proven tumors including 31 HCCs and 6 dysplastic nodules. The ratio of the Kupffer-cell count in the tumorous tissue relative to that in the nontumorous tissue (Kupffer-cell-count ratio) decreased as HCCs became less well differentiated. The ratio of the intensity of the tumorous lesion to that of the nontumorous area on SPIO-enhanced MR images (SPIO intensity ratio) correlated inversely with Kupffer-cell-count ratio in HCCs and dysplastic nodules (r ؍ ؊.826, P < .001) and increased as the degree of differentiation of HCCs decreased, indicating that the uptake of SPIO in HCCs decreased as the degree of differentiation of HCCs declined. All of the dysplastic nodules and some well-differentiated HCCs showed hypointense or isointense enhancement, relative to the surrounding liver parenchyma, indicating greater or similar uptake of SPIO in the tumor when compared with nontumorous areas. These results suggest that SPIO-enhanced MR imaging reflects Kupffer-cell numbers in HCCs and dysplastic nodules, and is useful for estimation of histological grading in HCCs, although uncertainties persist in differentiating dysplastic nodules from well-differentiated HCCs. (HEPATOLOGY 2000;32:205-212.) Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and a major cause of death in patients with cirrhosis. [1][2][3][4] One of the characteristics of HCC detected by imaging modalities such as computed tomography (CT), magnetic resonance (MR) imaging, and CT angiography, is increased arterial blood flow accompanied by decreased portal blood flow, although some well-differentiated HCCs do not show such blood supply characteristics. [5][6][7][8][9] Another characteristic of HCC, distinct from other metastatic tumors, has recently been clarified by Tanaka et al., 10 namely, that some well-differentiated HCCs have similar numbers of Kupffer cells as do the surrounding nontumorous regions of the liver.Superparamagnetic iron oxide (SPIO) is a tissue-specific MR imaging contrast that is taken up by Kupffer cells in the liver and macrophages in the spleen. 11,12 Because metastatic liver cancers lack Kupffer cells, hepatic metastases do not take up SPIO and thus appear hyperintense relative to the surrounding liver, being useful for the detection of metastatic liver cancers. [11][12][13][14] In an animal model of HCC, Kawamori et al., 15 studied whether SPIO-enhanced MR imaging could allow HCC to be distinguished from hyperplastic nodules. They concluded that SPIO-enhanced MR imaging may be useful in differentiating HCC from hyperplastic nodules, although some HCC nodules were difficult to differentiate from hyperplastic nodules, even after S...
Polypeptides in the dorsal root ganglion (L) of the adult rat were radioactively labeled, and components slowly migrating in the sciatic nerve (peripheral axons) and dorsal root (central axons) were analyzed, using SDS-polyacrylamide slab gel electrophoresis and fluorography . In particular, the transport rates and amounts of six major polypeptides, i .e ., the triplet (reference 15 ; with mol wts of 200,000, 160,000, and 68,000 daltons), a-and ,ß-tubulins and actin were compared between the two axon branches .
In the sensory fibers of the rat sciatic nerve (fibers of the dorsal root ganglion cells), two components of tubulin transport were observed that differed in the rate of transport, solubility in Triton, and subunit composition. The faster component, migrating ahead of the neurofilament proteins, was soluble in 1% Triton. The slower component, migrating with the neurofilament proteins, was insoluble in 1% Triton and contained a unique polypeptide, "NAP," in the tubulin region that was not present in the faster component. "NAP" was not a subspecies of tubulin as evidenced by peptide mapping. It seems to be a neurofilament-associated protein. When a complete separation of the main tubulin wave from the neurofilament wave was achieved in the motor axons of the same nerve (axons of the ventral motoneurons) under the effect of beta,beta'-iminodipropionitrile, a portion of tubulin was still found associated with the retarded neurofilament wave. The subunit composition of this portion was similar to the slower, neurofilament-associated component in the sensory fibers under normal conditions, i.e., enriched in "NAP" and the most acidic subtype of beta-tubulin. It is suggested that two populations of transported tubulin exist that are differentiated by the extent of their interaction with neurofilaments.
Previously, we have purified a spectrin-like calmodulin-binding protein termed calspectin from a membrane fraction of brain (14, 15). Calspectin, composed of oc (240,000-Mr) and ,6' (235,000-M,) subunits, is located predominantly in membranes and can be released from them with media used for the extraction of spectrin from erythrocyte ghosts but not with Triton X-100. By correlative biochemical and electronmicroscopic studies, we now provide evidence that the calspectin molecule undergoes dimer-tetramer interconversion in solution (existing as a tetramer in 0.1 M .I{Cl, and as a dimer in 0.6 M KCI). Although the dimer and tetramer are both bound to actin filaments, only the tetramer can cross-link actin to form a viscous gel. Electron microscopic images of calspectin molecules obtained by a low angle rotaryshadowing technique show extended, flexible rod-like shapes of 220 nm (tetramer) in length, which is very similar to the reported images of erythrocyte spectrin. The heterodimetric form appears to consist of on and ,8 monomers lying side by side.The tetrameric form appears to consist of two heterodimers joined head-to-head, with the actin binding sites appearing at the tail ends of the dimers. Calspectin and fodrin (24), which is recently purified and characterized as a spectrin-like calmodulinbinding protein (10), are probably one and the same.
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