Reverse epidemiology: a spurious hypothesis or a hardcore reality?

In maintenance hemodialysis (MHD) patients, associations between demographic, clinical and laboratory values and mortality, including cardiovascular death, are significantly different and, in some cases, in the opposite direction of those derived from the general population. This phenomenon, termed 'reverse epidemiology', is not limited to MHD patients but is also observed in populations that encompass an estimated 20 million Americans including those with an advanced age, heart failure, malignancies, and AIDS. A significant portion of this reversal may be due to the overwhelming effect of the malnutrition-inflammation complex syndrome (MICS). Since two thirds of MHD patients die within 5 years of initiation of dialysis treatment, traditional cardiovascular risk factors such as obesity, hypercholesterolemia and hypertension cannot exert a long-term deleterious impact, and instead, their short-term beneficial effects on MICS provides a survival advantage. In order to improve survival and quality of life in MHD patients, extrapolated ideal norms derived from the general population should be substituted with novel norms obtained from outcome-oriented epidemiologic analyses while accounting for the differential effect of MICS in different case-mix subgroups.

Effect of displacement and distortion of potential energy surfaces and overlapping resonances of electronic transitions on surface-enhanced Raman scattering: Models and ab initio theoretical calculation

A previously developed theory for the temperature-dependent resonance Raman scattering is used to study the surface-enhanced Raman scattering. Two models, the displaced oscillator model and the displaced-distorted oscillator model, based on the harmonic potential energy surfaces are carried out to calculate the surface-enhanced Raman scattering excitation profiles of the pyridine molecule adsorbed on a silver electrode, for which the density functional theory method is applied to evaluate the potential energy surfaces of the adsorption structure. In this framework, the distortion effect on the surface-enhanced Raman scattering will be discussed by comparing both models. The overlapping resonance of multiexcited electronic transitions is also studied, in which the interference between electronic transitions has been taken into account. It will be used to study the abnormal band at 1005.6 cm(-1) with the exciting radiation 457.9 nm.

Theoretical differential Raman scattering cross-sections of totally-symmetric vibrational modes of free pyridine and pyridine-metal cluster complexes

The differential Raman scattering cross-sections of totally-symmetric vibrational modes for pyridine and pyridine-metal clusters have been calculated by using ab initio and density functional methods. The results are compared with experimental data and a good agreement is obtained. In particular, we can theoretically reproduce the significant changes in the relative Raman intensities of the nu(12) mode in pyridine-metal cluster complexes. We focus on two mechanisms for these Raman intensities changes: (1) the chemical interaction between the pyridine and the metal clusters; and (2) the charge transfer mechanism. For the pyridine-silver cluster complexes, we find that due to the weak bonding, the chemical interaction does not influence the relative intensities of the Raman peaks of the nu(1) and nu(12) modes. However, in the case where the copper or the gold clusters are attached to pyridine, the intensity of the band of the nu(12) mode is weakened significantly. We also find that the charge transfer mechanism increases the asymmetry of the bands of the nu(1) and nu(12) modes on all three metals.

Systemically expressed soluble Tie2 inhibits intraocular neovascularization

Retinal and choroidal neovascularization are the most frequent causes of severe and progressive vision loss. Studies have demonstrated that Tie2, an endothelial-specific receptor tyrosine kinase, plays a key role in angiogenesis. In this study, we determined whether adenovirus-mediated gene delivery of extracellular domain of the Tie2 receptor (ExTek) could inhibit experimental retinal and choroidal neovascularization. Immunofluorescence histochemistry with a monoclonal antibody to human Tie2 showed that Tie2 expression is prominent around and within the base of newly formed blood vessels of retinal and choroidal neovascular lesions. A single intramuscular injection of adenovirus expressing ExTek genes achieved plasma levels of ExTek exceeding 500 microg/ml in mice for 10 days (in neonates) and 7 days (in adults). This treatment inhibited retinal neovascularization by 47% (p < 0.05) in a murine model of ischemia-induced retinopathy. The same treatment reduced the incidence and extent of sodium fluorescein leakage from choroidal neovascular lesions by 52% (p < 0.05) and 36% (p < 0.01), respectively, in a laser-induced murine choroidal neovascularization model. The same mice showed a 45% (p < 0.001) reduction of integrated area of the choroidal neovascularization. These findings indicate that Tie2 signaling is a common component of the angiogenic pathway in both retinal and choroidal neovascularization, providing a potentially useful target in the treatment of intraocular neovascular diseases.

Tolerance to cyclosporin A-induced autologous graft-versus-host disease is mediated by a CD4+CD25+ subset of recent thymic emigrants

Our previous studies revealed that both the autoeffector and immunoregulatory T cells in cyclosporin A (CSA)-induced autologous graft-vs-host disease are recent thymic emigrants (RTEs). The autoeffector cells appear in and are released from the thymus during the first week of CSA treatment, whereas the immunoregulatory thymocytes appear during the second week but are not released until several days after cessation of CSA treatment. In the present study, the antigenic phenotypes of these functional T cell subsets were determined by immunomagnetic separation and flow immunocytometric analysis. During CSA wk 1, the autoeffector T cells in both the thymus and lymph node (LN) expressed a CD4+8+ double-positive (DP) phenotype, after which those in the LN became CD8 single positive (SP). Timed thymectomy experiments confirmed that the CD8-SP autoeffector T cells in LN originated from these DP RTEs. During CSA wk 2, the immunoregulatory thymocytes also displayed a DP phenotype. However, they were not exported to the periphery until several days after CSA treatment had been interrupted and they had acquired a CD4-SP phenotype. In LN, these immunoregulatory RTEs expressed the CD25+ marker characteristic of anergic/suppressor T cells. Cell separation and mixing experiments demonstrated that the autoeffector T cells persist in LN after cessation of CSA treatment, but their activity is not detectable in the presence of recently exported CD4+ T cells. Hence, the results indicate that tolerance to CSA-induced autologous graft-vs-host disease is actively mediated by CD25+CD4+ RTEs that suppress the function of CD8 autoeffector T cells.

Relationship between phenotypes of cell-function differentiation and pathobiological behavior of gastric carcinomas

AIM

To reveal the correlation between the functional differentiation phenotypes of gastric carcinoma cells and the invasion and metastasis by a new way of cell-function classification.

METHODS

Surgically resected specimens of 361 gastric carcinomas(GC) were investigated with enzyme-, mucin-, and tumor-related marker immunohistochemistry. According to the direction of cell-function differentiation, stomach carcinomas were divided into five functionally differentiated types.

RESULTS

(1) Absorptive function differentiation type (AFDT): there were 82 (22.7%) patients including 76 (92.7%) aged 45 years. Sixty-nine (84.1%) cases belonged to the intestinal type. Thirty-eight (46.3%) expressed CD44v6 and 9 (13.6%) of 66 male patients developed liver metastasis. The 5-year survival rate of patients in this group (58.5%) was higher than those with the other types (P<0.01). (2) Mucin secreting function differentiation type (MSFDT): 54 (15%) cases. Fifty-three (98.1%) tumors had penetrated the serosa, 12 (22.2%) expressed ER and 22 (40.7%) expressed CD44v6. The postoperative 5-year survival rate was 28.6%. (3) Absorptive and mucin-producing function differentiation type (AMPFDT): there were 180 (49.9%) cases, including 31 (17.2%) aged younger than 45 years. The tumor was more common in women (62, 34.4%,) and expressed more frequently estrogen receptors (ER) (129, 81.7%) than other types (P<0.01). Ovary metastasis was found in 12 (19.4%) out of 62 female subjects. The patients with this type GC had the lowest 5-year survival rate (24.7%) among all types. (4) Specific function differentiation type (SFDT): 13 (3.6%) cases. Nine (69.2%) tumors of this type derived from APUD system, the other 4 (30.7%) were of different histological differentiation. Sixty per cent of the patients survived at least five years. (5) Non-function differentiation type (NFDT): 32 (8.9%) cases. Nineteen (59.4%) cases had lymph node metastases but no one with liver or ovary metastasis. The 5-year survival rate was 28.1%.

CONCLUSION

This new cell-function classification of GC is helpful in indicating the characteristics of invasion and metastasis of GC with different cell-function differentiation phenotypes. Further study is needed to disclose the correlation between the cell-functional differentiation phenotypes and the relevant genotypes and the biological behavior of gastric carcinoma.

Analysis of ingredient and heating value of municipal solid waste

Great differences between municipal solid wastes (MSW) produced at different places and different times in terms of such parameters as physical ingredient and heating value lead to difficulty in effective handling of MSW. In this paper, ingredient, heating value and their temporal varying trends of typical MSW in Beijing were continuously measured and analyzed. With consideration of the process in pyrolysis and incineration, correlation between physical ingredients and heating values was induced, favorable for evaluation of heating value needed in handling of MSW from simple analysis of physical ingredients of it.

Promoter-specific targeting of human SWI-SNF complex by Epstein-Barr virus nuclear protein 2

The multiprotein human SWI-SNF (hSWI-SNF) complex is a chromatin-remodeling machine that facilitates transcription by overcoming chromatin-mediated gene repression. We had previously shown that hSNF5/INI1, an intrinsic, consistent component of the hSWI/SNF complex, is associated with Epstein-Barr nuclear antigen 2 (EBNA2) and have proposed that EBNA2 directs this complex to key EBNA2-responsive viral and cellular genes. Using chromatin immunoprecipitation and quantitative PCR, we show that antibodies directed against components of the hSWI-SNF complex preferentially precipitate chromatin-associated DNA that contains a targeted EBNA2-responsive element in the context of both episomal and cellular chromatin. This enrichment does not occur in EBNA2-negative cells or when the EBNA2-responsive element is mutated. The stable association of the hSWI-SNF complex with the EBNA2-responsive promoter can also be disrupted by deletion of the TATA element, suggesting that EBNA2 in itself is insufficient to mediate stable targeting of the hSWI-SNF complex. These results demonstrate that recruitment of the hSWI-SNF complex to selected promoters can occur in vivo through its interaction with site-specific activator proteins and that stable targeting may require the presence of basal transcription factors.

Leukemic HRX fusion proteins inhibit GADD34-induced apoptosis and associate with the GADD34 and hSNF5/INI1 proteins

One of the most common chromosomal abnormalities in acute leukemia is a reciprocal translocation involving the HRX gene (also called MLL, ALL-1, or HTRX) at chromosomal locus 11q23, resulting in the formation of HRX fusion proteins. Using the yeast two-hybrid system and human cell culture coimmunoprecipitation experiments, we show here that HRX proteins interact directly with the GADD34 protein. We have found that transfected cells overexpressing GADD34 display a significant increase in apoptosis after treatment with ionizing radiation, indicating that GADD34 expression not only correlates with apoptosis but also can enhance apoptosis. The amino-terminal third of the GADD34 protein was necessary for this observed increase in apoptosis. Furthermore, coexpression of three different HRX fusion proteins (HRX-ENL, HRX-AF9, and HRX-ELL) had an anti-apoptotic effect, abrogating GADD34-induced apoptosis. In contrast, expression of wild-type HRX gave rise to an increase in apoptosis. The difference observed here between wild-type HRX and the leukemic HRX fusion proteins suggests that inhibition of GADD34-mediated apoptosis may be important to leukemogenesis. We also show here that GADD34 binds the human SNF5/INI1 protein, a member of the SNF/SWI complex that can remodel chromatin and activate transcription. These studies demonstrate, for the first time, a gain of function for leukemic HRX fusion proteins compared to wild-type protein. We propose that the role of HRX fusion proteins as negative regulators of post-DNA-damage-induced apoptosis is important to leukemia progression.

Cyclosporin A-induced autologous graft-versus-host disease: a prototypical model of autoimmunity and active (dominant) tolerance coordinately induced by recent thymic emigrants

Cyclosporin A (CSA)-induced autologous graft-vs-host disease (autoGVHD) is an autoimmune syndrome initiated by autoeffector T cells presumed to be exported from the thymus during CSA treatment. The appearance of noncytotoxic immunoregulatory T cell activity after cessation of CSA treatment is also thymus dependent. In the present study, we have tested the hypothesis that both autoeffector and immunoregulatory T cells in CSA-treated rats are recent thymic emigrants (RTEs). Local syngeneic graft-vs-host reaction (synGVHR) and timed thymectomy (Tx) assays revealed that autoeffector T cells appear initially in the thymus and are promptly exported to lymph nodes (LN) during the first week of CSA treatment. In contrast, immunoregulatory thymocytes are first detectable by local synGVHR inhibition assays during the second week of CSA treatment but are not exported to LN until approximately 4 days post-CSA. Both the autoeffector and immunoregulatory T cells in LN express Thy-1, a selective marker for RTEs in the rat. However, the autoeffector RTEs have a CD4+8+ phenotype, whereas the immunoregulatory RTEs have a CD4+8- phenotype. Thus, the coordinate formation in and release from the thymus cortex and medulla of autoeffector and immunoregulatory T cells in CSA-treated rats directly demonstrates that centrally induced, nondeletional tolerance can serve as a fail-safe mechanism by which clones of autoeffector T cells that have escaped intrathymic negative selection for self-MHC class II Ag can be suppressed postthymically.

A role for tectal midline glia in the unilateral containment of retinocollicular axons

Retinal fibers approach close to the tectal midline but do not encroach on the other side. Just before the entry of retinal axons into the superior colliculus (SC), a group of radial glia differentiates at the tectal midline; the spatiotemporal deployment of these cells points to their involvement in the unilateral containment of retinotectal axons. To test for such a barrier function of the tectal midline cells, we used two lesion paradigms for disrupting their radial processes in the neonatal hamster: (1) a heat lesion was used to destroy the superficial layers of the right SC, including the midline region, and (2) a horizontally oriented hooked wire was inserted from the lateral edge of the left SC toward the midline and was used to undercut the midline cells, leaving intact the retinorecipient layers in the right SC. In both cases, the left SC was denervated by removing its contralateral retinal input. Animals were killed 12 hr to 2 weeks later, after intraocular injections of anterograde tracers to label the axons from the remaining eye. Both lesions resulted in degeneration of the distal processes of the tectal raphe glia and in an abnormal crossing of the tectal midline by retinal axons, leading to an innervation of the opposite ("wrong") tectum. The crossover occurred only where glial cell attachments were disrupted. These results document that during normal development, the integrity of the midline septum is critical in compartmentalizing retinal axons and in retaining the laterality of the retinotectal projection.

Giant ossified cavernous hemangioma of an extremity associated with an equinovarus deformity

A 39-year-old woman suffered from swelling and tenderness of the right leg for 31 years. Imaging studies showed a large soft tissue lesion on the right side extending from the proximal portion of the thigh to the ankle. She underwent several operations due to the leg mass and associated equinovarus deformity of the right ankle. The pathologic findings were those of an ossified cavernous hemangioma. This appears to be one of the largest hemangiomas to be reported. It revealed the three types of calcification characteristic of hemangiomas. Equinovarus deformity of the ankle caused by contracture of the calf in this case was probably related to repeated bleeding.

Direct thymic involvement in anterior chamber-associated immune deviation: evidence for a nondeletional mechanism of centrally induced tolerance to extrathymic antigens in adult mice

Recent reports have suggested that the dichotomy between central (thymic) and peripheral T cell tolerance is not absolute and that self-tolerance in perinatal animals may also involve the intrathymic generation and release to the periphery of Ag-specific immunoregulatory T cells. We have expanded this concept to include tolerance to non self Ags administered extrathymically to adult animals. In this study, we use the anterior chamber-associated immune deviation (ACAID) to demonstrate that central regulation of acquired peripheral tolerance can be induced in adult mice by the intraocular administration of low doses of nonself Ag. The results show that adult thymectomy prevents the inhibition of trinitrophenol (TNP)-specific delayed-type hypersensitivity, which normally occurs after injection of TNP-BSA into the anterior chamber (AC) of the eye. Thymocytes obtained from mice 1 to 3 days, but not 5 to 7 days, after AC injection of TNP-BSA or BSA alone specifically transfer inhibition of delayed-type hypersensitivity to mice primed with the homologous Ag. The latter observation, when correlated with the time of onset of ACAID, suggests that immunoregulatory T cells are formed in the thymus within 24 h and are exported to the peripheral lymphoid tissues between 2 and 5 days after AC injection of Ag. Immunomagnetic separation of thymocytes revealed that the immunoregulatory activity resides within the minor subset of CD4-, CD8-, TCR-alphabeta+ cells, previously postulated to induce fas ligand-mediated apoptosis and Th1 to Th2 immune deviation. Hence, the present study identifies ACAID as a prototypical model of centrally induced, nondeletional tolerance to extrathymic nonself Ags.

Direct thymic involvement in anterior chamber-associated immune deviation: evidence for a nondeletional mechanism of centrally induced tolerance to extrathymic antigens in adult mice

Recent reports have suggested that the dichotomy between central (thymic) and peripheral T cell tolerance is not absolute and that self-tolerance in perinatal animals may also involve the intrathymic generation and release to the periphery of Ag-specific immunoregulatory T cells. We have expanded this concept to include tolerance to non self Ags administered extrathymically to adult animals. In this study, we use the anterior chamber-associated immune deviation (ACAID) to demonstrate that central regulation of acquired peripheral tolerance can be induced in adult mice by the intraocular administration of low doses of nonself Ag. The results show that adult thymectomy prevents the inhibition of trinitrophenol (TNP)-specific delayed-type hypersensitivity, which normally occurs after injection of TNP-BSA into the anterior chamber (AC) of the eye. Thymocytes obtained from mice 1 to 3 days, but not 5 to 7 days, after AC injection of TNP-BSA or BSA alone specifically transfer inhibition of delayed-type hypersensitivity to mice primed with the homologous Ag. The latter observation, when correlated with the time of onset of ACAID, suggests that immunoregulatory T cells are formed in the thymus within 24 h and are exported to the peripheral lymphoid tissues between 2 and 5 days after AC injection of Ag. Immunomagnetic separation of thymocytes revealed that the immunoregulatory activity resides within the minor subset of CD4-, CD8-, TCR-alphabeta+ cells, previously postulated to induce fas ligand-mediated apoptosis and Th1 to Th2 immune deviation. Hence, the present study identifies ACAID as a prototypical model of centrally induced, nondeletional tolerance to extrathymic nonself Ags.

Epstein-Barr virus nuclear protein 2 (EBNA2) binds to a component of the human SNF-SWI complex, hSNF5/Ini1

Epstein-Barr nuclear antigen 2 (EBNA2), one of the six viral nuclear proteins expressed in latently infected B lymphocytes, is essential to the immortalization of B cells by Epstein-Barr virus (EBV). EBNA2 promotes transcriptional transactivation of viral and cellular genes by acting as an adapter molecule that binds to cellular sequence-specific DNA-binding proteins, JK recombination signal-binding protein (RBP-JK), and PU.1 and engages multiple members of the RNA polymerase II transcription complex. In the present study, we show that EBNA2 also interacts with hSNF5/Ini1, the human homolog of the yeast transcription factor SNF5. Gel filtration fractionation of partially purified EBV-positive lymphocyte nuclear extracts shows that a fraction of EBNA2 coelutes with both hSNF5/Ini1 and BRG1, a human homolog of SWI/SNF2, in the high-molecular-mass region (1.5 to 2.0 MDa) of a Superose 6 chromatogram. An affinity-purified rabbit antibody directed against hSNF5/Ini1 coimmunoprecipitates EBNA2 from this high-molecular-mass nuclear protein fraction, demonstrating that EBNA2 and hSNF5/Ini1 interact in vivo. This interaction is restricted to a subpopulation of phosphorylated viral EBNA2. Deletion mutation analysis of EBNA2 shows that the proline-rich aminoterminal end and a domain within the divergent region of EBNA2 mediate EBNA2-hSNF5/Ini1 interaction. Since the SNF-SWI complex participates in gene regulation through the alteration of nucleosome configuration and may be a component of the RNA polymerase II holoenzyme, the EBNA2-hSNF5/Ini1 interaction supports the hypothesis that EBNA2 facilitates transcriptional transactivation by acting as a transcription adapter molecule. We postulate that EBNA2 engages the hSNF-SWI complex to generate an open chromatin conformation at the EBNA2-responsive target genes, thereby potentiating the function of the RBP-JK-EBNA2-polymerase II transcription complex.

Association of beta 1 integrin with phosphotyrosine in growth cone filopodia

Filopodia of growth cones are key elements in the transduction of extracellular cues that guide axon growth during development. How they are specialized to carry out this role is poorly understood. We previously had found tyrosine phosphorylated protein to be heavily concentrated at the tips of many filopodia of Aplysia growth cones in certain culturing conditions, suggesting that tyrosine phosphorylation might be involved in filopodial specialization. Immunocytochemistry was used to analyze the protein composition of the tip aggregates to determine whether there was an association of the tip phosphorylation with any important extracellular cue. beta 1 integrin, a subunit of the receptor for laminin-type neurite growth promoters, coconcentrated with phosphotyrosine at filopodial tips of both Aplysia and mouse growth cones. Several observations indicated that the association of beta 1 integrin with phosphotyrosine is close. beta 1 integrin and phosphotyrosine are known to colocalize at focal contacts, sites of adhesion of cells to the extracellular matrix, but the composition and behavior of the tip aggregates mark them as distinct structures. Also found in the tip aggregates was a member of the ezrin-radixin-moesin family of proteins, which are thought to link membrane proteins to submembranous bundles of actin filaments. Use of an inhibitor of protein-tyrosine kinases to deplete tip phosphotyrosine also caused disappearance of beta 1 integrin from the tip, suggesting a role for tyrosine phosphorylation in facilitating interaction of growth cones with certain environmental cues by fostering the aggregation of receptors in filopodia.

Abnormalities in the export and fate of recent thymic emigrants in diabetes-prone BB/W rats

Abnormalities in postthymic T cell development in the BB/W rat model of autoimmune insulin-dependent diabetes mellitus (IDDM) result in part from a lymphopenia (lyp) gene defect. To better characterize these abnormalities, the phenotypes of T cells from diabetes-prone (DP) and diabetes-resistant (DR) coisogenic rats were analyzed by multiparameter flow immunocytometry (FCM). Marked decreases in the numbers of Thy1- RT6+ T cells, most of which are CD8+, were documented in DP rats by live-gating. Conversely, an approximately 3-fold increase was observed in the percentage of Thy1+ RT6- T cells, which normally serve as the precursors of both Thy1- RT6+ and Thy1- RT6- T cell subsets in rats. These results suggested that, at a minimum, an arrest in maturation of the Thy1+ precursors of RT6+ T cells occurs postthymically in DP rats. To determine more precisely the stage(s) in T cell development at which lymphopenia occurs, the export and fate of recent thymic emigrants (RTE's) and their immediate descendants in DP rats was traced after intrathymic (i.t.) labelling with fluorescein isothiocyanate (FITC). The results showed that in DP, as compared with DR, rats: 1) 5-fold fewer RTE's are exported from the thymus per 24 hr; 2) more than 80% of the RTE's are CD4+; 3) most of the immediate descendants of RTE's disappear from the peripheral lymphoid tissues within one week after export from the thymus; and 4) few of the descendants of the RTE's that do survive differentiate into RT6+ T cells. Staining with propidium iodide revealed that a significantly higher proportion of Thy1+ T cells in DP than in DR rats are in cycle (S/G2/M), thereby accounting for their disproportionately high numbers relative to RTE's. These results indicate that, in addition to defective thymic export, most of the immediate descendants of RTE's in DP rats undergo non-productive proliferation and death at the time (3-7 days postthymic) at which their counterparts in DR rats differentiate into Thy1- RT6+ T cells. The resulting deficiency of immunoregulatory T cells, acting in concert with defective intrathymic selection of effector T cell precursors, appears to conspire to markedly enhance the predisposition of DP rats to autoimmunity.

Tyrosine phosphorylation and protrusive structures of the growth cone

Protein-tyrosine kinase, such as those of the trk and Eph families, serve as membrane receptors for extracellular cues which regulate the rate and direction of growth of numerous groups of axons. Certain cytoplasmic protein-tyrosine kinases, such as src, are also abundant in growth cones. But, how protein-tyrosine phosphorylation regulates the growth cone is poorly understood. We discuss here potential roles for tyrosine phosphorylation in the protrusive structures of the growth cone, especially filopodia, which are important in detecting cues. A particular focus is the integrin receptor for substrate-bound growth promoters like laminin. Changes in tyrosine phosphorylation may be important in both facilitating and mediating the interaction of filopodia with these growth promoters.

Computed tomography and magnetic resonance imaging of diffuse pigmented villonodular synovitis: report of a case

We describe the computed tomographic (CT) and magnetic resonance imaging (MRI) features of a surgically proven case of diffuse pigmented villonodular synovitis (PVNS) of the knee in a 34-year-old woman. A complex mass consisting of solid and multicystic components was clearly demonstrated by CT and MRI. The solid part showed homogeneous hypodense attenuation relative to adjacent muscles on CT scans, but it showed inhomogeneous signal intensity on spin echo T1- and T2-weighted images (WI). The solid component enhanced homogeneously on CT scans but heterogeneously on MR images. Multiseptated enhancement of the cystic component on both CT and MR images were displayed. All of the above features were better demonstrated on MRI. Multiple marked hypointense round and patchy areas, and also a few areas isointense to subcutaneous fat within the lesion were also found on T1WI, proton density WI and T2WI. These characteristic MRI features of PVNS correlated well with its histologic structures: depositions of hemosiderin and fat in the proliferative synovial villi and bloody cystic content. These features may help to distinguish PVNS from other disease entities arising from the synovium.

Inhibition of formation of filopodia after axotomy by inhibitors of protein tyrosine kinases

The activity of motile protrusions of the growth cone--filopodia, veils, and lamellipodia--is essential for directed growth of a neuronal process. The regulation of the formation of these protrusions is not well understood. Numerous filopodia and veils or lamellipodia form within minutes of transection of an Aplysia axon in culture, as the initial components of growth cones of regenerating neurites. Axotomy, therefore, provides a robust and reliable protocol for analyzing the formation of these protrusions. We evaluated the involvement of protein phosphorylation in the regulation of protrusive activity. Of the inhibitors of protein kinases assayed, only the inhibitors of protein tyrosine kinases--genistein, lavendustin A, herbimycin A, and erbstatin analogue--suppressed the formation of protrusions, as assessed by high magnification video microscopy. These drugs did not work by preventing resealing of the axon, as evident from visual inspection and by the unimpaired effectiveness of genistein or lavendustin in preventing formation of filopodia when applied after resealing. Inhibition of protein tyrosine kinases not only prevented the formation of actin-based protrusions, but also caused deterioration of the actin network underlying the protrusive area of preexisting growth cones. Consistent with an involvement of protein tyrosine phosphorylation in the generation of protrusive structures, immunocytochemistry revealed that aggregates of phosphotyrosine appeared at the margins of the axon, from which protrusions emerge shortly after axotomy. These results suggest a role for protein tyrosine phosphorylation in the formation and maintenance of actin-based protrusive structures.

Glial environment in the developing superior colliculus of hamsters in relation to the timing of retinal axon ingrowth

We have examined the developmental changes of glial cell organization in the superior colliculus of embryonic and neonatal hamsters in reference to the known sequence of retinal axon ingrowth and arborization in the midbrain. Immunolocalization of vimentin, a marker for neuronal and glial cell precursors, reveals a uniform distribution of radially oriented cells, with perikarya located at the ventricular surface and thin, elongated processes fanning out toward the pia. These vimentin-positive cells, referred to as the lateral radial cells, are present in the tectum from embryonic day (E) 10 (earliest day examined) until approximately postnatal day (P) 5. Vimentin expression in the lateral radial cells decreases markedly during the second week of postnatal life: application of DiI to the ventricular surface reveals that the pial attachment of the lateral radial cells is withdrawn and that the radial processes are gradually pulled back toward the ventricular zone. By P14, virtually no vimentin-positive radial cells are detectable in the superior colliculus. At no time during development are the lateral radial cells immunopositive for the glial fibrillary acidic protein (GFAP); however, shorter, vimentin-positive astrocytic profiles can be seen in the tectum around the time the radial fibers have been withdrawn, suggesting that at least some radial cells are transformed into astrocytes that will colonize the mature colliculus. At approximately E12, a second group of cells, referred to as the midline radial glia, is detected at the tectal midline. These cells are tightly bundled, forming a raphe in the tectum. They are intensely vimentin positive from E13 until at least P14. From the time of birth, the midline radial cells also exhibit intense immunoreactivity for GFAP. The lateral radial cells are present in the superior colliculus prior to and during the period of neurogenesis but remain well past the time when collicular neuronal migration is completed. Pial processes of the lateral radial cells are present within the superficial tectal layers during the time retinal axons are entering this target; they may be involved in directing the growth and initial collateralization of retinotectal axons. Their withdrawal from retinorecipient collicular zones begins at about the time arbors are being elaborated on retinal axons. In contrast, the midline glia become distinct just prior to the time retinal axons enter the superior colliculus and persist during the time retinotectal projections are being fully established. These raphe glia may be involved in maintaining the laterality of the retinotectal projection.

Brachial plexus neuropathy secondary to septic arthritis and osteomyelitis: report of two cases

Two infants, delivered uneventfully, later developed right brachial plexus palsy secondary to pyogenic osteomyelitis and arthritis of the right shoulder joint. Weakness of right arms occurred at the sixth and tenth days of age respectively. Both had right arm tenderness on palpation and passive movement. Roentgenograms of their right shoulder joints showed irregular radiolucency of the proximal margin of right humerus head. In both cases, electromyography revealed various degrees of significant denervation pattern for the C5-C7 innervated muscles. Pus culture from right shoulder joints grew Streptococcus viridans and Staphylococcus aureus, respectively. After antibiotic therapy and arthrotomy with drainage, weakness improved gradually following continuous rehabilitation. Follow-up at six months of age showed almost complete recovery of right upper extremity function in one patient, but mild residual weakness in the other. Follow-up electromyography studies showed continued improvement. The possible mechanism of this rare occurrence is discussed.

Regulated tyrosine phosphorylation at the tips of growth cone filopodia

Several types of evidence suggest that protein-tyrosine phosphorylation is important during the growth of neuronal processes, but few specific roles, or subcellular localizations suggestive of such roles, have been defined. We report here a localization of tyrosine-phosphorylated protein at the tips of growth cone filopodia. Immunocytochemistry using a mAb to phosphorylated tyrosine residues revealed intense staining of the tips of most filopodia of Aplysia axons growing slowly on a polylysine substrate, but of few filopodia of axons growing rapidly on a substrate coated with Aplysia hemolymph, which has growth-promoting material. Cytochalasin D, which causes F-actin to withdraw rapidly from the growth cone, caused the tyrosine-phosphorylated protein to withdraw rapidly from filopodia, suggesting that the protein associates or interacts with actin filaments. Phosphotyrosine has previously been found concentrated at adherens junctions, where bundles of actin filaments terminate, but video-enhanced contrast-differential interference contrast and confocal interference reflection microscopy demonstrated that the filopodial tips were not adherent to the substrate. Acute application of either hemolymph or inhibitors of protein-tyrosine kinases to neurons on polylysine resulted in a rapid loss of intense staining at filopodial tips concomitant with a lengthening of the filopodia (and their core bundles of actin filaments). These results demonstrate that tyrosine-phosphorylated protein can be concentrated at the barbed ends of actin filaments in a context other than an adherens junction, indicate an association between changes in phosphorylation and filament dynamics, and provide evidence for tyrosine phosphorylation as a signaling mechanism in the filopodium that can respond to environmental cues controlling growth cone dynamics.