Intracranial peripheral primitive neuroectodermal tumors of the cavernous sinus: a diagnostic peculiarity

Peripheral primitive neuroectodermal tumors (pPNETs) are aggressive, poorly differentiated neoplasms that occur in children and young adults. These tumors are associated with a peak incidence in the second decade and a slight male preponderance. Recently, Ewing sarcoma and pPNET tumors have been proven to carry identical translocations, the most common being t(11;22)(q24;q12). Intracranial Ewing sarcoma/pPNETs have rarely been described in the literature. We studied a case of intracranial pPNET arising in the right cavernous sinus of a 46-year-old man. On imaging, the tumor had both sellar and suprasellar components and was centered within the right parasellar region. Histologically, the tumor was composed of intermediate to large cells with round to oval hyperchromatic nuclei with distinct nucleoli. The cells contained a moderate amount of slightly basophilic cytoplasm. The tumor was markedly fibrotic and had collagen bands surrounding both individual and groups of cells. A large immunohistochemical panel was positive only for CD99 and vimentin. Fluorescence in situ hybridization did not show translocations associated with Ewing sarcoma/pPNET. However, a small percentage of these tumors can be negative for this translocation. In these cases, histology and immunohistochemical techniques in the absence of an alternative diagnosis are the only tools available to establish the diagnosis.     

Chromosomal aberrations and micronucleus frequency in nurses occupationally exposed to cytotoxic drugs

In this study, we evaluated the effect of low level occupationalexposure of nurses in a medical oncology unit in Cairo, Egypt,to anticancer drugs. Twenty nurses who constantly handled thesedrugs and 20 controls, matched according to age and sex, wereexamined. Metaphase chromosomes were studied. Percentages ofmetaphases with chromosomal aberrations were significantly higher(P < 0.001) in the exposed group (6.1 ± 2.7) versusthe controls (2.6 ± 1.6). The detected chromosomal aberrationswere in the form of chromatid gaps, chromatid breaks and acentricfragments. Micronucleated peripheral blood lymphocytes werealso analyzed in cytochalasin B treated binucleated lymphocytes.There was significant increase in cells with micronuclei (P< 0.001) in nurses (10.05 ± 4.71) in comparison tothe matched control (5.42 ± 2.22) (P < 0.001). Nursesexposed to the cytotoxic drugs for     

Infection of immunodeficient horses with Sarcocystis neurona does not result in neurologic disease

Equine protozoal myeloencephalitis is a progressive neurologic disease of horses most commonly caused by infection with the apicomplexan parasite Sarcocystis neurona. Factors affecting neuroinvasion and neurovirulence have not been determined. We investigated the pathogenesis of infection with S. neurona in horses with severe combined immune deficiency (SCID). Two immunocompetent (IC) Arabian horses and two Arabian horses with SCID were infected orally with 5 x 10(5) sporocysts of S. neurona. Four IC horses and one SCID horse were infected intravenously (i.v.) with 5 x 10(8) merozoites of the WSU-1 isolate of S. neurona. Despite prolonged parasitemia and persistent infection of visceral tissues (skeletal muscle, cardiac muscle, lung, liver, and spleen) as demonstrated by PCR and culture, SCID horses did not develop neurologic signs after oral or i.v. infection. S. neurona was undetectable in the neuronal tissues of SCID horses by either PCR, immunohistochemistry, or culture. In contrast, although parasitemia was undetectable in orally infected IC horses and of only short duration in i.v. infected IC horses, four of six IC horses developed neurologic signs. S. neurona was detectable by PCR and/or culture of neural tissue but not visceral tissue of IC horses with neurologic disease. Infected SCID horses are unable to clear S. neurona from visceral tissues, but the infection does not result in neurologic signs; in contrast, IC horses rapidly control parasitemia and infection of visceral tissues but frequently experience neuroinvasion and exhibit clinical signs of neurologic disease.     

A characterization of glycinergic receptors present in cultured rat medullary neurons.

1. Whole-cell current responses to bath application of glycine, beta-alanine, and taurine were studied in medullary neurons cultured from embryonic rats. 2. Two current components were seen in the responses to bath application of agonist, one component that desensitized and another that did not. 3. The two current components have different dose-response characteristics, with the nondesensitizing component being activated more effectively at lower concentrations than the desensitizing component and also reaching its peak at lower concentrations. The agonist concentrations producing half-maximal responses are 26 +/- 4 (SE, n = 6) and 69 +/- 17 (n = 7) microM for the nondesensitizing and desensitizing components, respectively, for glycine; 54 +/- 7 (n = 9) and 127 +/- 37 (n = 7) microM for beta-alanine; and 153 +/- 24 (n = 9) 443 +/- 99 (n = 3) microM for taurine. Thus, for each component, the order of potency is glycine greater than beta-alanine greater than taurine. 4. When total responses to glycine, beta-alanine, and taurine are compared in the same cells, taurine and beta-alanine are less potent agonists than glycine, with relative potencies of 1:0.4:0.1 for glycine-beta-alanine-taurine. 5. The desensitizing component is more sensitive to strychnine than the nondesensitizing one. The strychnine concentrations that block 50% of the response to a control dose of agonist are 15 and 500 nM for the desensitizing and nondesensitizing components, respectively, for glycine; 60 nM and 1 microM for beta-alanine; and 18 and 500 nM for taurine. 6. The complete occlusion between the responses to glycine and beta-alanine or glycine and taurine suggests that these agonists activate the same receptors. 7. The two current components may be manifestations of one receptor population with complicated kinetics or two independent receptor populations.     

Memory CD8+ T cell differentiation: initial antigen encounter triggers a developmental program in naïve cells

The rules that govern memory T cell differentiation are not well understood. This study shows that after antigenic stimulation na?ve CD8+ T cells become committed to dividing at least seven times and differentiating into effector and memory cells. Once the parental na?ve CD8+ T cell had been activated, this developmental process could not be interrupted and the daughter cells continued to divide and differentiate in the absence of further antigenic stimulation. These data indicate that initial antigen encounter triggers an instructive developmental program that does not require further antigenic stimulation and does not cease until memory CD8+ T cell formation.     

Phosphate glasses for tissue engineering: Part 2. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass fibre system

This paper presents the results of a study of the thermal properties, solubility and dimensions of a range of phosphate-based glass fibres (PB-GFs). The glass compositions were limited by fixing the P2O5 content to 45, 50 and 55 mol%, and varying the CaO mol% at 30, 35 and 40. PB-GFs were obtained from the 50 and 55 mol% P2O5 compositions; however, we were unable to obtain fibres from the 45 mol% compositions. This was linked to the cross-linked density, network connectivity and average chain length of the compositions studied. With regards to thermal parameters investigated, initial data showed an increase of the Tg and crystallisation temperatures with increasing CaO mol% at each fixed phosphate content. A decrease in Tg temperatures was also observed with increasing P2O5 content to 55 mol%. The crystallisation temperatures obtained for compositions with fixed phosphate at 55 mol%, showed a reverse pattern, with a decrease in values as compared to the fixed 50 mol% phosphate compositions. The diameters of the fibres all decreased with increasing RPMs as expected, and the solubility also increased with increasing RPMs. This was related to the increased surface area of the higher RPM fibres. There was also a decrease seen in solubility with increasing CaO mol%.