Cutaneous mucormycosis in a young, immunocompetent girl.

We report a case of cutaneous mucormycosis in a healthy, immunocompetent young girl (age 14 years). The patient had a 5-year history of a slowly enlarging, erythematous plaque with slight elevated, scaling, circinate borders on the right thigh. Histopathology showed a granulomatous infiltrate with broad, pale, non-septate hyphae. Mycological study identified Mucor hiemalis (Wehmer).     

Mechanisms of the ATP potentiation of hyposmotic taurine release in Swiss 3T3 fibroblasts

Reducing osmolarity by 35% increased ³H-taurine efflux from Swiss 3T3 fibroblasts from 0.5% to a peak of 5.7%. The presence of ATP (10–100 µM; EC₅₀ 1.5 µM) increased taurine efflux up to 10%, and decreased the set point for hyposmotically stimulated taurine release (HTR). ATP potentiation was mimicked by UTP, reduced by addition of suramin and pyridoxal phosphate-6-azophenyl-2,4-disulphonic acid (PPADS) and unaffected by ADP, ,-methylene-ATP (,-ATP) or 2-methylthio-ATP (Me-ATP), suggesting its mediation by purinergic P2Y₂ and P2Y₄ metabotropic receptors. Under isosmotic conditions ATP increased the cytosolic [Ca²⁺] ([Ca²⁺]_i) markedly, but did not increase taurine release. HTR was independent of external Ca²⁺ but was reduced (by 56–59%) by BAPTA-AM, thapsigargin-induced depletion of intracellular Ca²⁺ stores, or phospholipase C (PLC) inhibition. Blockade of calmodulin (CaM) or calmodulin kinase II (CaMKII) reduced HTR by 54% and 76%, respectively. The ATP-mediated potentiation was prevented fully by all these treatments. HTR was reduced by 30–50% by blockers of protein tyrosine kinases (AG18), phosphoinositide 3-kinase (PI3K) (wortmannin), p21rho (toxin B), p21rho-kinase (Y27632) and the stress-activated kinase p38 (PD169316). ATP-mediated potentiation was reduced similarly by these blockers. Simultaneous inhibition of PI3K and CaMKII abolished HTR. Altogether, these results suggest a modulatory effect of ATP, probably exerted by a potentiation of the Ca²⁺-dependent fraction of HTR. This fraction has as signalling elements a PLC-dependent [Ca²⁺]_i increase, resulting from Ca²⁺ released from thapsigargin-sensitive internal stores, followed by activation of CaM/CaMKII reactions. The Ca²⁺/ATP effect operates only when the Ca²⁺-independent, tyrosine kinase-mediated pathway is already activated. Suggested elements of cross-talk between the two pathways are PLC, PI3K and CaMKII.     

Genetic Variability of HIV-1 Protease from Nigeria and Correlation with Protease Inhibitors Drug Resistance

In Nigeria, the most populous country in Africa, the characterization of HIV-1 strains has been limited. In this study we evaluated the genetic diversity of the protease coding region, one of the anti-retroviral therapy target, and investigated the presence of mutations related to resistance to HIV protease inhibitors. We analyzed samples collected during 1996 and all patients were anti-retroviral drug na¨ves. Ten samples were evaluated by sequencing of the protease gene. The majority, 80%, were classified as subtype A and the two others were unclassified-divergent strains, something in between A and G subtypes. The gag region from these outliners were sequenced and the phylogenetic analysis classified them as subtype G. The protease amino acid consensus sequence of the Nigerian subtype A are in complete agreement with the consensus A differing from the USA subtype B consensus in 10 positions (L10V, I13V, K14R, I15V, K20I, M36I, R41K, P63L, H69K and L89M).The secondary substitutions associated with protease inhibitor resistance were observed in all Nigerian sequences at the positions L10V, M36I and L89M. The majority of sequence variation was concentrated in the interval between aminoacids 70–90 where the protease substrate binding region is located.     

The paraventricular nucleus of hypothalamus mediates the pressor response to noradrenergic stimulation of the medial prefrontal cortex in unanesthetized rats

The medial prefrontal cortex (MPFC) is a structure that is also involved in cardiovascular modulation. The injection of norepinephrine (NE) into the prelimbic (PL) area of the MPFC of unanesthetized rats evokes a pressor response which is mediated by acute vasopressin release. Vasopressin is synthesized by magnocellular cells of the paraventricular (PVN) and supraoptic nucleus (SON) of the hypothalamus. In the present study, we endeavored to determine which vasopressin-synthesizing hypothalamic nucleus is involved in the pressor pathway activated after NE injection into the PL area of the MPFC. We report here that lidocaine microinjection into the SON did not change the pressor response evoked by NE injection into the PL. However, the response to NE was blocked by prior injection of lidocaine or CoCl₂ into the PVN, indicating that this area is responsible for the mediation of this pressor response. A neuroanatomic experiment in which the neuronal tracer biotinylated dextran amine (BDA) was microinjected into the MPFC showed a lack of axons or neuronal cell bodies in the PVN, indicating that there are no direct connections between the PL area of the MPFC and the PVN. The results suggest that the PVN is involved in the mediation of the pressor response to NE in the PL area and that this pathway must relay in other brain structures before reaching the PVN.     

Major histocompatibility complex status in breast carcinogenesis and relationship to apoptosis

Major histocompatibility complex (MHC) molecules are of central importance in regulating the immune response against tumors. In this study we used immunohistochemistry to study human leukocyte antigen (HLA) class I and II antigen expression in normal breast tissues and benign, preneoplastic, primary, and metastatic breast lesions using antibodies against beta-2-microglobulin (beta2-m), heavy-chain, and HLA-DR antigens. Whereas all normal tissues and benign lesions were positive for beta2-m and HLA-A, -B, and -C antigens, total loss of HLA class I antigens was found in 37% (11 of 30) of in situ carcinomas, in 43% (56 of 131) of the primary tumors, and in 70% (31 of 45) of the lymph node metastases. HLA-DR was also underexpressed in breast cancer cells; thus 20% (6 of 30) of in situ carcinomas, 15% of invasive carcinomas (20 of 131), and only 1 metastatic case were positive for this antigen. Both HLA class I and II antigen expression were more frequently down-regulated in metastatic lesions than in primary breast lesions (P <0.05), and a tendency toward a simultaneous defective expression of HLA class I and II antigens was observed in primary carcinomas (P = 0.07). However, no correlation was found between the expression of any of the aforementioned molecules and pathological parameters or survival. Interestingly, HLA class I expression was expressed more frequently in tissues with high apoptotic activity and was significantly associated with the expression of the proapoptotic bax gene (P = 0.02), and was inversely associated with expression of the antiapoptotic bcl-2 gene (P = 0.03). We conclude that alterations in HLA class I and II antigen expression are early events in breast carcinogenesis and play significant roles in metastatic progression. In addition, their expression is correlated with apoptosis-regulating proteins, which may influence the cytotoxicity of T cells against HLA class I-specific tumor antigens.     

Genetic ablation of FLRT3 reveals a novel morphogenetic function for the anterior visceral endoderm in suppressing mesoderm differentiation

During early mouse development, the anterior visceral endoderm (AVE) secretes inhibitor and activator signals that are essential for establishing the anterior–posterior (AP) axis of the embryo and for restricting mesoderm formation to the posterior epiblast in the primitive streak (PS) region. Here we show that AVE cells have an additional morphogenetic function. These cells express the transmembrane protein FLRT3. Genetic ablation of FLRT3 did not affect the signaling functions of the AVE according to the normal expression pattern of Nodal and Wnt and the establishment of a proper AP patterning in the epiblast. However, FLRT3^−/− embryos showed a highly disorganized basement membrane (BM) in the AVE region. Subsequently, adjacent anterior epiblast cells displayed an epithelial-to-mesenchymal transition (EMT)-like process characterized by the loss of cell polarity, cell ingression, and the up-regulation of the EMT and the mesodermal marker genes Eomes, Brachyury/T, and FGF8. These results suggest that the AVE acts as a morphogenetic boundary to prevent EMT and mesoderm induction in the anterior epiblast by maintaining the integrity of the BM. We propose that this novel function cooperates with the signaling activities of the AVE to restrict EMT and mesoderm induction to the posterior epiblast.