Sex-specific modulation of spinal nociception by alpha2-adrenoceptors: differential regulation by estrogen and testosterone

Sex-related differences in antinociception produced by the activation of alpha(2)-adrenoceptors (alpha(2)-ARs) have been reported, however, the precise role of gonadal steroids is still unknown. Hence, we hypothesized that estrogen and testosterone modulate antinociceptive effects of clonidine (an alpha(2)-AR agonist) on N-methyl-D-aspartate- (NMDA) and heat-induced spinal nociception. We also investigated whether estrogen or testosterone alters the expression of alpha(2A)-adrenoceptors in the spinal cord. Sprague-Dawley (SD) rats were implanted with PE10 cannulae in the intrathecal space of the lumbosacral spinal cord and divided into male, proestrous and diestrous female, ovariectomized (OVX), estradiol-treated OVX (OVX+E), castrated male (GDX), testosterone (GDX+T) and estradiol-treated castrated male (GDX+E) groups. Clonidine dose-dependently inhibited NMDA-induced scratching behavior in the male and OVX groups but to a significantly lesser extent in the OVX+E group. It also increased the tail withdrawal latency in the male, OVX, diestrous and GDX+T groups but not in the OVX+E, proestrous, GDX and GDX+E groups. Levels of alpha(2A)-AR mRNA were significantly higher in the OVX, estradiol-treated OVX, GDX and GDX+E animals. In contrast, alpha(2A)-AR protein levels were higher in estradiol-treated OVX, GDX, GDX+T and GDX+E animals as compared with the male. Indeed, no correlations were observed between changes in the mRNA or protein levels of alpha(2A)-AR and behavioral observations. These results support our hypothesis that sex-related differences in alpha(2)-AR-mediated modulation of spinal nociception are gonadal hormone-dependent: estrogen attenuates antinociceptive effects in females whereas testosterone is required for the expression of antinociception in males. In addition, results also revealed that the mechanism of action of gonadal hormones may not involve a global alternation in expression of alpha(2A)-AR in the spinal cord. Estrogen-induced attenuation of alpha(2)-AR-mediated inhibition of nociception could contribute to the higher prevalence of pain syndromes in women.

Nodular invasive tracheobronchitis due to Aspergillus in a patient with systemic lupus erythematosus

Nodular or pseudomembranous tracheobronchitis due to infection by Aspergillus species is an uncommon presentation of invasive aspergillosis. Most cases have been described in severely immunocompromised hosts. We describe the case of a 23-year-old woman, with recently diagnosed systemic lupus erythematosus, who developed worsening respiratory function. Bronchoscopy revealed rapid development and progression of multiple nodular plaques in her trachea and bronchi. Endobronchial biopsy demonstrated invasive fungal infection with tissue necrosis and the presence of hyphal elements consistent with aspergillosis. To the best of our knowledge, this is only the second report of fulminant invasive tracheobronchitis due to Aspergillus in a patient with an autoimmune disease.

Activation of phosphatidylinositol 3-kinase is necessary for differentiation of FDC-P1 cells following stimulation of type III receptor tyrosine kinases

Signaling molecules that are responsible for proliferation and differentiation of hematopoietic cells following ectopic expression of receptor tyrosine kinases (RTKs) were investigated in the interleukin 3 (IL-3)-dependent hematopoietic cell line, FDC-P1. Cells were transfected with human platelet-derived growth factor receptor (PDGF-R), macrophage colony stimulating factor-1 receptor (CSF-1R), epidermal growth factor receptor (EGF-R), and chimeras consisting of the extracellular domain of EGF-R and the transmembrane and cytoplasmic domains of either HER2 (HER1-2) or c-kit (EK-R). All FDC-P1 transfectants proliferated in response to the corresponding growth factor in the absence of IL-3. However, only cells expressing PDGF-R, CSF-1R, and EK-R (type III RTKs) differentiated along the monocyte-macrophage lineage after treatment with their activating ligands. Analysis of proteins from these RTK-expressing cells revealed that a Mr 85,000 protein showed in vitro phosphorylation, and V8 protease peptide mapping showed that this protein was p85, the regulatory subunit of phosphatidylinositol 3-kinase (PI3-kinase). Accordingly, activation of PDGF-R-, CSF-1R-, and EK-R-expressing cells led to an increase in PI3-kinase activity. Expression of EK-R mutant Y721F, which lacked the known p85 binding site, blocked differentiation and activation of PI3-kinase, without affecting proliferation. Last, addition of wortmannin to cells expressing PDGF-R, CSF-1R, and EK-R blocked ligand-induced differentiation in a concentration-dependent manner, and this effect correlated with wortmannin's ability to inhibit PI3-kinase. Thus, ectopic expression of both type I and III RTKs could stimulate FDC-P1 proliferation in the absence of IL-3; however, only activation of type III RTKs led to differentiation via selective coupling to p85 and PI3-kinase activation.

The "VH1-like" dual-specificity protein tyrosine phosphatases

The number of dual-specificity protein tyrosine phosphatases has grown considerably in the last few years, and thus it would be helpful to organize these novel enzymes. The simple term "VH1-like" or "dual-specificity" phosphatase does not adequately reflect the different subclasses within this new and important phosphatase subfamily. In this article, we review the salient features of dual-specificity phosphatases and propose a novel classification scheme of these enzymes based on their structural motifs. Classification of dual-specificity phosphatases based on their motifs should serve as a useful organizational framework for bringing together this now large subgroup of phosphatases. Moreover, this classification scheme may hold predictive value, since some of these motifs may hold the key to new, undiscovered functional properties.

Tissue-specific expression of splice variants of the mouse voltage-gated calcium channel alpha2/delta subunit

Five different splice variants of mouse alpha2/delta subunit isoforms (alpha2a-e), which arose from various combinations of three alternatively spliced regions, were cloned with a combination of cDNA library screening and RT-PCR. Expression patterns and relative abundance of the various isoforms in mouse tissues were determined with an RNAse protection assay. Skeletal muscle and brain expressed single isoforms, alpha2a and alpha2b, respectively; however, the cardiovascular system expressed all five isoforms. Heart expressed mainly isoforms alpha2c and alpha2d while, in contrast to other species, aorta expressed predominantly alpha2a, the 'skeletal muscle' isoform. Smooth muscle-containing tissues expressed alpha2d and alpha2e. Thus, alpha2/delta isoforms are restricted in their tissue expression, suggesting an important functional role for the differentially spliced variants.