Aortic dissection: diagnosis and follow-up with helical CT

Acute aortic dissection is a cardiovascular emergency that requires prompt diagnosis and treatment. Helical computed tomography (CT) allows diagnosis of acute aortic dissection with a sensitivity and specificity of nearly 100%. With helical CT, a dissection involving the ascending aorta (type A in the Stanford classification) can be differentiated from one distal to the left subclavian artery (type B). Helical CT can also be used to identify atypical forms of aortic dissection such as intramural hematoma, penetrating atherosclerotic ulcer, ruptured type B dissection, and atypical configurations of the intimal flap. Helical CT is useful in follow-up of aortic dissection by allowing assessment of early and late changes after surgery or medical treatment. Such changes include postoperative complications of type A dissection, healing of intramural hematoma, progression of intramural hematoma, and aneurysms of the true or false lumen. Helical CT can also be used to monitor potentially life-threatening ischemic complications of abdominal branch vessels.

Evidence for the participation of the neuron-specific CDK5 activator P35 during laminin-enhanced axonal growth

Cultures of cerebellar macroneurons were used to study the pattern of expression, subcellular localization, and function of the neuronal cdk5 activator p35 during laminin-enhanced axonal growth. The results obtained indicate that laminin, an extracellular matrix molecule capable of selectively stimulating axonal extension and promoting MAP1B phosphorylation at a proline-directed protein kinase epitope, selectively stimulates p35 expression, increases its association with the subcortical cytoskeleton, and accelerates its redistribution to the axonal growth cones. Besides, suppression of p35, but not of a highly related isoform designated as p39, by antisense oligonucleotide treatment selectively reduces cdk5 activity, laminin-enhanced axonal elongation, and MAP1b phosphorylation. Taken collectively, the present results suggest that cdk5/p35 may serve as an important regulatory linker between environmental signals (e.g., laminin) and constituents of the intracellular machinery (e.g., MAP1B) involved in axonal elongation.

Suppression of radixin and moesin alters growth cone morphology, motility, and process formation in primary cultured neurons

In this study we have examined the cellular functions of ERM proteins in developing neurons. The results obtained indicate that there is a high degree of spatial and temporal correlation between the expression and subcellular localization of radixin and moesin with the morphological development of neuritic growth cones. More importantly, we show that double suppression of radixin and moesin, but not of ezrin-radixin or ezrin-moesin, results in reduction of growth cone size, disappearance of radial striations, retraction of the growth cone lamellipodial veil, and disorganization of actin filaments that invade the central region of growth cones where they colocalize with microtubules. Neuritic tips from radixin-moesin suppressed neurons displayed high filopodial protrusive activity; however, its rate of advance is 8-10 times slower than the one of growth cones from control neurons. Radixin-moesin suppressed neurons have short neurites and failed to develop an axon-like neurite, a phenomenon that appears to be directly linked with the alterations in growth cone structure and motility. Taken collectively, our data suggest that by regulating key aspects of growth cone development and maintenance, radixin and moesin modulate neurite formation and the development of neuronal polarity.

High-density lipoprotein aggregated by oxidation induces degeneration of neuronal cells

We have previously reported that high-density lipoprotein (HDL) exhibits antineuritogenic effects on chicken cerebral cells in culture. In the present study, we show the effects of HDLs, oxidized by UV irradiation or heating, on chicken cerebral neurons in culture. Both treatments produced several physical and chemical changes in the HDLs, i.e., formation of lipid peroxides, enlargement of HDL diameters, an increased exposure of the tryptophan groups of the apolipoprotein A-I to a more hydrophilic environment, formation of bityrosines, and cross-linking of apolipoprotein A-I. When these treatments were performed in the absence of EDTA, most of the modifications described above were more intense and HDLs formed a macroaggregate that displays a rosette-like structure. The aggregated HDLs produced neurodegeneration and death when added to both undifferentiated and differentiated cerebral neurons in culture. This process was accompanied by the disorganization of the cellular microtubular cytoskeleton and hyperphosphorylation of the microtubule-associated protein tau. Native HDL or HDLs treated in the presence of EDTA inhibited the neuritogenesis of undifferentiated neurons but did not show any significant effect on the differentiated neurons in culture. The effects on the cellular cytoskeleton and morphology of aggregated HDLs recall those of the fibrillar beta-amyloid peptide. The present results suggest that aggregated HDLs could participate in neurodegeneration associated with oxidative stress in the CNS.

Suppression of KIF2 in PC12 cells alters the distribution of a growth cone nonsynaptic membrane receptor and inhibits neurite extension

In the present study, we present evidence about the cellular functions of KIF2, a kinesin-like superfamily member having a unique structure in that its motor domain is localized at the center of the molecule (Noda Y., Y. Sato-Yoshitake, S. Kondo, M. Nangaku, and N. Hirokawa. 1995. J. Cell Biol. 129:157-167.). Using subcellular fractionation techniques, isopicnic sucrose density centrifugation of microsomal fractions from developing rat cerebral cortex, and immunoisolation with KIF2 antibodies, we have now identified a type of nonsynaptic vesicle that associates with KIF2. This type of organelle lacks synaptic vesicle markers (synapsin, synaptophysin), amyloid precursor protein, GAP-43, or N-cadherin. On the other hand, it contains betagc, which is a novel variant of the beta subunit of the IGF-1 receptor, which is highly enriched in growth cone membranes. Both betagc and KIF2 are upregulated by NGF in PC12 cells and highly concentrated in growth cones of developing neurons. We have also analyzed the consequences of KIF2 suppression by antisense oligonucleotide treatment on nerve cell morphogenesis and the distribution of synaptic and nonsynaptic vesicle markers. KIF2 suppression results in a dramatic accumulation of betagc within the cell body and in its complete disappearance from growth cones; no alterations in the distribution of synapsin, synaptophysin, GAP-43, or amyloid percursor protein are detected in KIF2-suppressed neurons. Instead, all of them remained highly enriched at nerve terminals. KIF2 suppression also produces a dramatic inhibition of neurite outgrowth; this phenomenon occurs after betagc has disappeared from growth cones. Taken collectively, our results suggest an important role for KIF2 in neurite extension, a phenomenon that may be related with the anterograde transport of a type of nonsynaptic vesicle that contains as one of its components a growth cone membrane receptor for IGF-1, a growth factor implicated in nerve cell development.

Small bowel obstruction secondary to bezoar: CT diagnosis

Two cases of small bowel obstruction secondary to phytobezoar diagnosed by computed tomography (CT) and confirmed at surgery are presented. CT findings were dilated intestinal loops and an intraluminal mass with air bubbles retained in its interstices, resulting in a mottled appearance. We propose that definite diagnosis of small bowel bezoar can be made on the basis of these CT findings.

Duodenal schwannoma causing gastrointestinal bleeding: helical CT findings

Neurogenic tumors of the small intestine are extremely rare and represent an unusual cause of gastrointestinal hemorrhage. We present a case of schwannoma of the fourth portion of the duodenum demonstrated by helical computed tomography. Multiplanar reconstructions showed a hypervascular tumor arising from the inferior wall of the duodenum. The use of water as oral contrast agent instead of iodinated contrast permitted a better visualization of the intact mucosa and differentiated a hypervascular tumor from hypodense gastrointestinal content.

Expression and distribution of IGF-1 receptors containing a beta-subunit variant (betagc) in developing neurons

Betagc is a beta-subunit variant of the insulin-like growth factor-1 (IGF-1) receptor highly enriched in growth cone membranes prepared by subcellular fractionation of fetal rat brain (). The present study is focused on the expression and on the cellular and subcellular distribution of betagc in developing neurons and differentiating PC12 cells. In the developing cerebral cortex and, at least at early stages, in cultured primary neurons, betagc expression was found to be correlated with neurite outgrowth. In PC12 cells betagc expression was nerve growth factor (NGF)-dependent and also paralleled neurite outgrowth. In contrast, beta-subunits of the insulin receptor and/or of other IGF-1 receptors ("betaP5"; detected with antibody AbP5) were downregulated as betagc expression increased. Immunofluorescence studies confirmed the enrichment of betagc at growth cones and demonstrated morphologically its spatial separation from betaP5, which is confined to the perikaryon. At the growth cone, betagc colocalizes and associates in a proximal region with microtubules, but it seems independent of the more peripheral microfilaments. Some betagc immunoreactivity is detected in the perinuclear region of PC12 cells, most likely the Golgi complex and its vicinity. betagc seems to emerge from the periphery of this structure in an apparently vesicular compartment distinct from that carrying synaptophysin to the growth cones. The facts that (1) betagc expression is correlated closely with neurite outgrowth, that (2) it is regulated in PC12 cells by a neurotrophin, NGF, and that (3) betagc is concentrated in the proximal growth cone region raise new questions regarding a possible role of IGF-1 receptors containing betagc in the regulation of neurite growth.

CT evaluation of underlying cause in spontaneous subcapsular and perirenal hemorrhage

We evaluated the CT scans of 13 patients with spontaneous subcapsular or perinephric hemorrhage (SPH) associated with these underlying causes: 4 angiomyolipomas, 2 renal cell carcinomas, 1 renal metastatic malignant melanoma, 1 ruptured renal artery aneurysm, 1 adrenal myelolipoma, 1 ruptured renal abscess, 2 ruptured hemorrhagic cysts, and 1 patient with undiagnosed coagulation disorder. Our objective was to ascertain whether an underlying cause of SPH was identifiable by CT, and to determine the extension of the hematomas. Computed tomography identified the hematoma in all 13 cases (sensitivity 100 %). In all 12 cases in which there was a renal or adrenal anatomic lesion, the underlying cause was identified with CT (100 %), with correct diagnosis in 11 cases (91.6 %). The case in which no lesion was identified was the undiagnosed coagulation disorder. We conclude that CT is a useful technique for the initial evaluation of SPH, permitting diagnosis of hemorrhage and identification of the underlying cause.

Axonal origin and purity of growth cones isolated from fetal rat brain

The investigation of the molecular properties of nerve growth cones depends to a significant degree on their isolation from fetal brain in the form of 'growth cone particles' (GCPs). The availability of markers for developing axons and dendrites, as well as glial cells, has made it possible to characterize the GCP fraction in much greater detail than before and to optimize its yield. Marker analyses show that a member of the N-CAM family (5B4-CAM), synaptophysin, and especially GAP-43 and non-phosphorylated tau, are enriched in the GCP fraction. In contrast, MAP2 and, particularly, glial fibrillary acidic protein and vimentin are fractionated away from GCPs. Furthermore, GCP yield can be doubled relative to the original procedure, without compromising purity, by raising the sucrose concentration of the fractionation gradient's uppermost layer. The results indicate that GCPs are highly purified growth cone fragments with very little glial contamination, and that they are primarily of axonal origin.

Spontaneous aortocaval fistula: CT findings with pathologic correlation

We present a case of aortocaval fistula (ACF) secondary to spontaneous rupture of an atherosclerotic infrarenal aortic aneurysm into the inferior vena cava that was initially diagnosed with computed tomography (CT). This is believed to be the first report of this condition with CT demonstration of the exact site of fistula and CT-pathologic correlation. We retrospectively reviewed the CT findings of another two cases of ACF and the previous literature.

High-density lipoprotein inhibits UDP-N-acetylgalactosamine:GM3, N-acetylgalactosaminyltransferase and differentiation of cultured cerebral cells: comparison with a formerly described inhibitor of this enzyme

We have previously described a thermostable inhibitor of the UDP-N-acetylgalactosamine:GM3,N-acetylgalactosaminyltransferase (GM2 synthase) purified from chicken blood serum. Some properties of the GM2 synthase inhibitory preparation (IP) resemble those of high-density lipoprotein (HDL), i.e., both have a MW of 200,000 in native conditions and are resistant to denaturation by heat. These and other facts prompted us to test the possibility that lipoproteins regulate ganglioside biosynthesis in the CNS. For this purpose, serum lipoprotein fractions were isolated from chicken serum by flotation and were assayed as inhibitors of GM2 synthase activity and of neuron differentiation in culture. HDL (in contrast to fractions containing very low-density or low-density lipoprotein) inhibited GM2 synthase with the same specific activity as IP and inhibited neuron cell differentiation in culture in a similar way. Furthermore, these two preparations also share several other characteristics; i.e., both have the same cholesterol content, the same floating behavior on KBr gradients, and the same polypeptide pattern as detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and staining with Coomassie Blue, or after western blot and revealing with an antibody prepared against IP, which is able to diminish the inhibitory effect of this preparation. The results described indicate identity between HDL and IP and suggest that HDL (particularly apolipoprotein A) could play an important role on ganglioside biosynthesis modulation during CNS development. The antineuritogenic effect of HDL described in this study could be of physiological relevance during CNS development and response to injury.

Insulin-like growth factor I receptors of fetal brain are enriched in nerve growth cones and contain a beta-subunit variant

Nerve growth cones isolated from fetal rat brain are highly enriched in a 97-kDa glycoprotein, termed beta gc, that comigrates with the beta subunit of the IGF-I receptor upon two-dimensional PAGE and is disulfide-linked to this receptor's alpha subunit. Antibodies prepared to a conserved domain shared by the insulin and IGF-I receptor beta subunits (AbP2) or to beta gc were used to study receptor distribution further. Subcellular fractionation of the fetal brain segregated most AbP2 immunoreactivity away from growth cones, whereas most beta gc immunoreactivity copurified with growth cones. Experiments involving ligand-activated receptor autophosphorylation confirmed the concentration of IGF-I but not of insulin receptors in growth cone fractions. These results indicate the enrichment of IGF-I receptors in (presumably axonal) growth cones of the differentiating neuron. Furthermore, the segregation of beta gc from AbP2 immunoreactivity suggests that such neurons express an immunochemically distinct variant of the IGF-I receptor beta subunit at the growth cone.

A direct non-competitive idiometric enzyme immunoassay for serum oestradiol

We report a novel non-competitive enzyme immunoassay for oestradiol based on the use of two types of anti-idiotypic antibody that recognize different epitopes within the hypervariable region of the primary anti-oestradiol idiotypic antibody (Ab1). The first anti-idiotype, the betatype, competes with the analyte for an epitope of the primary antibody at the binding site. On the other hand, the second anti-idiotype, the alphatype, binds to the Ab1 in the presence of analyte but does not bind to the betatype/Ab1 complex because of steric hindrance. In the present format the biotinylated alphatype was captured onto anti-biotin IgG which was adsorbed on the surface of microtitre wells. Reaction mixtures containing the Ab1 complexed sequentially with an enzyme labelled second antibody reagent, with oestradiol standards or serum samples and with the betatype anti-idiotypic antibody were then allowed to react with the immobilized alphatype anti-idiotypic antibody. The enzyme activity of the bound fraction measured at 405 nm increased with increasing oestradiol concentrations over the range 0.06-2.5 ng/ml. The detection limit of the assay was 28 pg/ml. The intra-assay variation ranged from 3.5 to 12.4%, and inter-assay variation from 6 to 13.4%. The results obtained by the colorimetric idiometric immunoassay correlated well with those obtained by a direct radioimmunoassay (n = 85, r = 0.97). This non-competitive immunoassay, termed idiometric assay, for haptens permits the development of sensitive immunoassays with a wide working range, and a variety of end-point determinations depending on the label used (e.g., enzyme, chemiluminescent or fluorogenic compound).

Characterization of gp93, a novel, highly heterogeneous glycoprotein present in growth cone membranes

gp93 was first described in growth cones from fetal rat brain as a 90-97-kDa glycoprotein family that binds wheat-germ agglutinin and consists of at least 12 different isoelectric variants (pl range approximately 4.9-6.4). Of particular interest is that different sets of gp93 variants are expressed in growth cones isolated from different brain regions. The preparation of a polyclonal antibody to gp93 allowed further characterization of this glycoprotein. The carbohydrate groups of gp93 were partially characterized by digestion with different glycosidases. The results indicate that most or all oligosaccharide units are N-linked (asparagine-linked) and contain sialic acid. Two-dimensional polyacrylamide gel electrophoresis and western blot with anti-gp93 show that deglycosylated gp93 is an only slightly heterogeneous polypeptide of 66 kDa, indicating that gp93 heterogeneity is due, primarily or exclusively, to differential glycosylation. Analysis of the tissue distribution in fetal rat showed gp93 to be highly enriched in the brain. Immunoblots and immunostaining of cross sections of developing cerebellum revealed that gp93 is developmentally regulated in this tissue, associated primarily with growing parallel fibers and Purkinje dendrites. Immunostaining of neurons in culture shows significant amounts of gp93 in elongating neurites and growth cones. Our results indicate that gp93 is a developmentally regulated glycoprotein of the brain that is most prominent in growth cones and growing neurites and that appears to be glycosylated differentially by different neurons.

Juvenile rheumatoid arthritis of the knee: evaluation with US

PURPOSE

To evaluate the value of ultrasound (US) in assessing joint inflammation in patients with juvenile rheumatoid arthritis (JRA) of the knee.

MATERIALS AND METHODS

US scans obtained in 36 children (mean age, 8 years) with JRA of the knee were compared with those obtained in 30 healthy children.

RESULTS

Changes in synovial membrane (synovial thickness), presence of fluid in the suprapatellar bursa, and alterations in the contour (blurring) of the articular cartilage showed statistically significant differences between JRA patients and control subjects. US was more sensitive than physical examination for detecting a minimal amount of intra-articular fluid in 21% of JRA-affected knees with no clinical evidence of active disease.

CONCLUSION

US is a simple, rapid, inexpensive, and accurate method for assessing joint inflammation in patients with JRA of the knee.

Spontaneous duodenal fistula due to hepatic hydatid cyst

Communication of a hepatic hydatid cyst to the duodenum appears to be extremely rare. This is the first case described in the imaging literature of hepatic echinococcosis fistulized to the duodenum studied by computed tomography.

Variable membrane glycoproteins in different growth cone populations

The question of whether growth cones generated by different neurons contain distinctive membrane glycoproteins was examined. Growth cone particles (GCPs) were isolated from specific regions of fetal or early postnatal brain, and their membrane proteins were analyzed by 2D gel electrophoresis and Western blotting, using WGA as a probe. These blots were compared to those generated by synaptosomes from adult brain. The patterns reveal a number of WGA-binding glycoproteins that are uniformly present in these subcellular fractions and others that are found in GCPs from selected brain regions only. The results indicate, therefore, substantial pattern diversity for the different, restricted growth cone populations. Some of the WGA-binding glycoproteins seen in GCPs disappear with increasing age and are absent from synaptosomes, while others seem to become more prominent. One of the glycoprotein complexes present in all GCP and synaptosome fractions analyzed is gp93. It has an apparent molecular weight of 90-97 kDa and exhibits unusually high heterogeneity in GCPs from whole fetal brain. The gp93 complex covers a pI range from about 4.9 to about 6.4 and consists of at least 12 different species, probably isoelectric variants. In GCPs from different brain regions, the sets of gp93 species observed are different and characteristic. Neuraminidase digestion shifts the gp93 pattern to a more neutral pI but simplifies it only partially, indicating that variable sialic acid content explains the molecular diversity to some extent. Thus, gp93 is a glycoprotein complex whose members are expressed and/or posttranslationally processed differentially in different growth cone populations. Such a glycoprotein family may be involved in selective cell-cell recognition.

Internalization of the inhibitor of the N-acetylgalactosaminyltransferase by chicken embryonic retina cells: reversibility of the inhibitor effects

Retina cells from 6-day-old chicken embryos were cultured in the presence of an 125I-labeled protein inhibitor of the UDP-N-acetylgalactosamine:GM3,N-acetylgalactosaminyltransferase. The cells were labeled and did not lose the incorporated radioactivity when treated with 0.125% trypsin or 1 M NaCl at 37 degrees C for 1 hr, indicating that the iodinated inhibitor was inside the cells. Immunostaining procedures using an anti-inhibitor antibody were applied to the cells cultured in the presence of the inhibitor after permeabilization of the cells. The inhibitor was found inside the round cells virtually devoid of neurites, but not in flat glial-like cells or in process-bearing neural cells. Also found was an apparent self-recovery effect of the cells for both the anti-neuritogenic effect and the modification of the pattern of labeled gangliosides produced by the inhibitor when the agent was withdrawn from the culture medium after the initial period of 20 hr. This recovery was clearly observed 72 hr after the removal of the inhibitor.

Growth-regulated proteins and neuronal plasticity. A commentary

Growth-regulated proteins (GRPs) of the neuron are synthesized during outgrowth and regeneration at an increased rate and enriched in nerve growth cones. Therefore, they can be used to some degree as markers of neurite growth. However, these proteins are not unique to the growing neuron, and their properties are not known sufficiently to assign them a functional and/or causal role in the mechanisms of outgrowth. During synaptogenesis, GRPs decrease in abundance, and growth cone functions of motility and organelle assembly are being replaced by junctional contact and transmitter release. However, there is a stage during which growth cone and synaptic properties overlap to some degree. We propose that it is this overlap and its continuation that allow for synaptic plasticity in developing and adult nervous systems. We also propose a hypothesis involving (a) trophic factor(s) that might explain the regulation of synaptic sizes and collateral sprouting. Some GRPs, especially GAP43/B50/pp46/F1, are more prominent in adult brain regions of high plasticity, and they undergo change, such as phosphorylation, during long-term potentiation (LTP). Without precise functional knowledge of GRPs, it is impossible to use changes in such proteins to explain the plasticity mechanism. However, changes in these "growth markers" are likely to be an indication of sprouting activity, which would explain well the various phenomena associated with plasticity and learning in the adult. Thus, plasticity and memory may be viewed as a continuation of the developmental process into adulthood.

[Maternal perception of the quality of care given to their children during hospitalization]

In order to evaluate the perception of mothers on the care given to their hospitalized children, a survey was specially designed and carried out with 100 mothers on the day of their child's discharge. Hospital care was rated excellent or good by a 96%, regular or bad by 4% of surveyed mothers. Most (74%) mothers saw at least one member of the caring team acting affectionately with their children; only 2% complained that her child was reprimanded or punished. Lack of equipment or human resources and comfort facilities were frequently perceived by mothers but quality of care was generally considered to be satisfactory. This kind of studies is probably useful to improve community's health services.

An endogenous inhibitor of N-acetylgalactosaminyltransferase inhibits retina neuron differentiation in culture

An inhibitor of N-acetylgalactosamine:GM3, N-acetylgalactosaminyltransferase (EC 2.4.1.92) from chicken blood serum, was tested for its activity on embryonic chicken neural retina in culture. The inhibitor did not change the cellular protein content of the cultures but produced a significant reduction of the labeling of gangliosides. The ratio of labeling of GD3 to GD1a increased from about 0.1 to about 0.8 in the cells cultured without or with the inhibitor, respectively. A striking effect of the inhibitor was seen on the morphology of the neurons, those cultured in its presence being practically devoid of neurites. Glial flat cells were apparently not affected.

Interovarian relationship in the secretion of progesterone during the luteal phase of the capuchin monkey (Cebus apella)

In basal conditions, progesterone concentrations were similar in the ovarian veins of the ovary +CL (3211 +/- 526 ng/ml) and the ovary -CL (3165 +/- 554 ng/ml), but after blocking the blood flow between the ovary +CL and the uterus, the progesterone values in the vein draining the ovary -CL decreased to 1218 +/- 394 ng/ml (P less than 0.01). When [3H]progesterone was injected in the ovary +CL, the radioactivity appeared earlier and more concentrated in the vein draining the ovary -CL (30 sec, 0.53% of injected dose) than in the femoral vein (150 sec, 0.08% of injected dose). Removal of the ovary +CL was followed by a brief maintenance of peripheral progesterone within luteal-phase levels. The in-vitro progesterone production by a suspension of cells isolated from the corpus luteum was 47.5 +/- 12.8 ng/ml/2 h, whereas luteal-like cells isolated from the ovary -CL secreted 14.3 +/- 6.0 ng/ml/2 h (P less than 0.01) into the medium. We therefore suggest that the symmetrical and high secretion rate of progesterone by the ovaries of the capuchin monkey indicates a between-ovary communication system, and that the luteal-like tissue of the ovary -CL can produce relatively large amounts of progesterone.