Comparative efficacy of low dose,daily versus alternate day plasma exchange in severe myasthenia gravis

Abstract Objective To evaluate the comparative efficacy of low dose daily versus alternate day plasma exchange in patients with severe myasthenia. Methods Thirty three patients with myasthenia gravis (Osserman's stage II b and III) were randomized to receive alternate day (n = 17) or daily low dose plasma exchange (n = 16). Plasma exchange were carried on each patient, number of exchanges varying subject to their requirements and 20-25 ml/kg plasma was removed during each session. Myasthenia gravis disease scale (MGDS) score was evaluated before and after the procedure. Time to wean off ventilator, removal of nasogastric tube and total duration of hospital stay were also assessed. Results There was no statistically significant difference between daily vs. alternate day group with regards to change in MGDS score, percentage change in MGDS score, and complication rates. A decreased hospital stay was observed in patients on daily plasma exchange which almost reached statistical significance. Conclusion We conclude from our study that daily and alternate day plasma exchange are similar in their efficacy and complication rates, however the daily schedule could be a preferred modality due to decreased hospital stay.     

Functional specialization of beta-arrestin interactions revealed by proteomic analysis

Beta-arrestins are cytosolic proteins that form complexes with seven-transmembrane receptors after agonist stimulation and phosphorylation by the G protein-coupled receptor kinases. They play an essential role in receptor desensitization and endocytosis, and they also serve as receptor-regulated signaling scaffolds and adaptors. Moreover, in the past decade, a growing list of protein-protein interactions of beta-arrestins pertinent to these functions has been documented. The discovery of several novel functions of beta-arrestins stimulated us to perform a global proteomics analysis of beta-arrestin-interacting proteins (interactome) as modulated by a model seven-transmembrane receptor, the angiotensin II type 1a receptor, in an attempt to assess the full range of functions of these versatile molecules. As determined by LC tandem MS, 71 proteins interacted with beta-arrestin 1, 164 interacted with beta-arrestin 2, and 102 interacted with both beta-arrestins. Some proteins bound only after agonist stimulation, whereas others dissociated. Bioinformatics analysis of the data indicates that proteins involved in cellular signaling, organization, and nucleic acid binding are the most highly represented in the beta-arrestin interactome. Surprisingly, both S-arrestin (visual arrestin) and X-arrestin (cone arrestin) were also found in heteromeric complex with beta-arrestins. The beta-arrestin interactors distribute not only in the cytoplasm, but also in the nucleus as well as other subcellular compartments. The binding of 16 randomly selected newly identified beta-arrestin partners was validated by coimmunoprecipitation assays in HEK293 cells. This study provides a comprehensive analysis of proteins that bind beta-arrestin isoforms and underscores their potentially broad regulatory roles in mammalian cellular physiology.     

Herpes simplex virus type 1 infection induces oxidative stress and the release of bioactive lipid peroxidation by-products in mouse P19N neural cell cultures

To determine whether herpes simplex virus type 1 (HSV-1) infection causes oxidative stress and lipid peroxidation in cultured neural cells, mouse P19 embryonal carcinoma cells were differentiated into cells with neural phenotypes (P19N cells) by retinoic acid and were then infected with HSV-1. Cellular levels of reactive oxygen species (ROS) and the release of lipid peroxidation by-products into the tissue culture medium were then measured by the generation of fluorescent markers hydroxyphenyl fluorescein and a stable chromophore produced by lipid peroxidation products, malondialdehyde (MDA) and hydroxyalkenals (4-HAEs; predominantly 4-hydroxy-2-nonenal [HNE]), respectively. HSV-1 infection increased ROS levels in neural cells as early as 1 h post infection (p.i.) and ROS levels remained elevated at 24 h p.i. This viral effect required viral entry and replication as heat- and ultraviolet light-inactivated HSV-1 were ineffective. HSV-1 infection also was associated with increased levels of MDA/HAE in the culture medium at 2 and 4 h p.i., but MDA/HAE levels were not different from those detected in mock infected control cultures at 1, 6, and 24 h p.i. HSV-1 replication in P19N cells was inhibited by the antioxidant compound ebselen and high concentrations of HNE added to the cultures, but was increased by low concentrations of HNE. These findings indicate that HSV-1 infection of neural cells causes oxidative stress that is required for efficient viral replication. Furthermore, these observations raise the possibility that soluble, bioactive lipid peroxidation by-products generated in infected neural cells may be important regulators of HSV-1 pathogenesis in the nervous system.     

Differential effects of the immunosuppressive agents cyclosporin A, tacrolimus and sirolimus on drug transport by multidrug resistance proteins

Purpose We sought to determine the effects of the immunosuppressants, cyclosporin A (CsA), tacrolimus and sirolimus, on drug transport by the ATP-binding cassette proteins, P-glycoprotein (Pgp; ABCB1), multidrug resistance protein-1 (MRP-1; ABCC1) and breast cancer resistance protein (BCRP; ABCG2), and the major vault protein lung resistance protein (LRP). Methods Cellular content of mitoxantrone, a Pgp, MRP-1 and BCRP substrate, was measured by flow cytometry in cells overexpressing these proteins following incubation with and without CsA, tacrolimus or sirolimus. Interaction of BCRP with these compounds was studied by photolabeling and ATPase assays. Nuclear–cytoplasmic distribution of doxorubicin was studied by confocal microscopy in cells overexpressing LRP. Results CsA increased cellular drug uptake in cells overexpressing Pgp, MRP-1 or BCRP and nuclear drug uptake in cells overexpressing LRP at the clinically achievable concentration of 2.5 μM. Tacrolimus enhanced cellular drug uptake at 1 μM, but not at 0.08 μM, its clinically achievable concentration, and did not enhance nuclear drug uptake. Sirolimus enhanced cellular drug uptake in cells overexpressing Pgp, MRP-1 and BCRP with optimal effects at 2.5 μM, but was effective at its clinically achievable concentration of 0.25 μM if cells were pre-incubated for at least 30 min before drug exposure, and also enhanced nuclear drug uptake at 0.25 μM. BCRP modulation by all three immunosuppressive agents was associated with competitive binding to the drug transport sites. Conclusions CsA, tacrolimus and sirolimus modulate drug transport by Pgp, MRP-1 and BCRP and CsA and sirolimus modulate drug transport by LRP at concentrations that differ from immunosuppressive concentrations and maximum tolerated concentrations.     

Computer visualization techniques (CVTs) foster evidence-based target delineation

Computer visualization techniques (CVTs) are an emerging technology that can organize all cancer specialists. This article describes CVTs' ability to maximize the currently untapped advantages of intensity modulated radiotherapy (IMRT). The visual speed and dynamic strategies inherent in CVTs improves IMRT by distilling vast amounts of anatomic, multimodal imaging, textual/meaning, and surgical/outcome data into a large, rigorous, standardized evidence base of storable target delineation plans. This ability to standardize strategies will allow the collection of meaningful evidence based outcome data.     

MGMT expression in oral precancerous and cancerous lesions: correlation with progression, nodal metastasis and poor prognosis

Alkylation of DNA at the O(6) position of guanine is a critical step in the induction of mutations by carcinogenic and chemotherapeutic alkylating agents. O(6)-methylguanine-DNA methyltransferase (MGMT) is an enzyme that removes mutagenic adducts from the O(6) position of guanine, thereby protecting the genome against guanine to adenine transitions. We hypothesized that alteration in MGMT expression might occur in early stages of development of oral cancer and be associated with disease progression. Immunohistochemical analysis of MGMT expression was carried out in 107 oral squamous cell carcinomas (OSCCs), 78 oral precancerous lesions (OPLs) (58 hyperplasias and 20 dysplasias) and 30 histologically normal oral tissues and correlated with clinicopathological parameters as well as major risk factors. Decreased MGMT expression was observed as early as in hyperplasia (p=0.003; Odd's Ratio (OR)=5.0). Significant loss of MGMT expression was observed from hyperplasia to dysplasia (p=0.034; OR=4.0). Loss of MGMT expression was associated with late clinical stage of OSCCs (p=0.027, OR=2.0) and nodal metastasis (p=0.031, OR=2.5). Decreased MGMT expression was associated with smokeless tobacco (ST) consumption in patients with OPLs (p=0.017, OR=3.6) and OSCCs (p=0.031, OR=2.8). Significant association was also observed between loss of MGMT expression and poor prognosis of OSCC patients (p=0.02; OR=5.2). The decreased MGMT expression in OPLs suggested that deregulation of MGMT expression is an early event in the development of oral cancer. In OSCCs, its correlation with late clinical stage, and nodal metastasis suggests association with aggressive tumor behavior and cancer progression, underscoring its potential as a candidate predictive marker for nodal metastasis and disease prognosis. Correlation of loss of MGMT expression with ST consumption underscored its significance in ST-associated oral carcinogenesis.