Stopping the clock on proteomic degradation by heat treatment at the point of tissue excision

The effectiveness of rapid and controlled heating of intact tissue to inactivate native enzymatic activity and prevent proteome degradation has been evaluated. Mouse brains were bisected immediately following excision, with one hemisphere being heat treated followed by snap freezing in liquid nitrogen while the other hemisphere was snap frozen immediately. Sections were cut by cryostatic microtome and analyzed by MALDI‐MS imaging and minimal label 2‐D DIGE, to monitor time‐dependent relative changes in intensities of protein and peptide signals. Analysis by MALDI‐MS imaging demonstrated that the relative intensities of markers varied across a time course (0–5 min) when the tissues were not stabilized by heat treatment. However, the same markers were seen to be stabilized when the tissues were heat treated before snap freezing. Intensity profiles for proteins indicative of both degradation and stabilization were generated when samples of treated and nontreated tissues were analyzed by 2‐D DIGE, with protein extracted before and after a 10‐min warming of samples. Thus, heat treatment of tissues at the time of excision is shown to prevent subsequent uncontrolled degradation of tissues at the proteomic level before any quantitative analysis, and to be compatible with downstream proteomic analysis.     

Coyotes (Canis latrans) are definitive hosts of Neospora caninum

Four captive-raised coyote pups consumed tissues from Neospora caninum-infected calves. Faeces were examined from 4 days before to 28 days after infection. One pup shed N. caninum-like oocysts, which tested positive for N. caninum and negative for Hammondia heydorni using PCR tests. Coyotes are the second discovered definitive host of N. caninum, after dogs. In North America, the expanding coyote ranges and population increase the probability of contact with domestic livestock. To reduce the risk of transmission of N. caninum to intensively farmed cattle, we recommend protection of feedstuffs using canid-proof fences, and careful disposal of dead stock.     

Calmodulin mediates Ca2+ sensitivity of sodium channels

Ca2+ has been proposed to regulate Na+ channels through the action of calmodulin (CaM) bound to an IQ motif or through direct binding to a paired EF hand motif in the Nav1 C terminus. Mutations within these sites cause cardiac arrhythmias or autism, but details about how Ca2+ confers sensitivity are poorly understood. Studies on the homologous Cav1.2 channel revealed non-canonical CaM interactions, providing a framework for exploring Na+ channels. In contrast to previous reports, we found that Ca2+ does not bind directly to Na+ channel C termini. Rather, Ca2+ sensitivity appears to be mediated by CaM bound to the C termini in a manner that differs significantly from CaM regulation of Cav1.2. In Nav1.2 or Nav1.5, CaM bound to a localized region containing the IQ motif and did not support the large Ca(2+)-dependent conformational change seen in the Cav1.2.CaM complex. Furthermore, CaM binding to Nav1 C termini lowered Ca2+ binding affinity and cooperativity among the CaM-binding sites compared with CaM alone. Nonetheless, we found suggestive evidence for Ca2+/CaM-dependent effects upon Nav1 channels. The R1902C autism mutation conferred a Ca(2+)-dependent conformational change in Nav1.2 C terminus.CaM complex that was absent in the wild-type complex. In Nav1.5, CaM modulates the Cterminal interaction with the III-IV linker, which has been suggested as necessary to stabilize the inactivation gate, to minimize sustained channel activity during depolarization, and to prevent cardiac arrhythmias that lead to sudden death. Together, these data offer new biochemical evidence for Ca2+/CaM modulation of Na+ channel function.     

Molecular design,synthesis, and structure-Activity relationships leading to the potent and selective p56(lck) inhibitor BMS-243117

A series of structurally novel benzothiazole based small molecule inhibitors of p56(lck) were prepared to elucidate their structure-activity relationships (SARs), selectivity and cell activity in the T-cell proliferation assay. BMS-243117 (compound 2) is identified as a potent, and selective Lck inhibitor with good cellular activity (IC(50)=1.1 microM) against T-cell proliferation.     

Discovery of 2-amino-heteroaryl-benzothiazole-6-anilides as potent p56(lck) inhibitors

A series of structurally novel benzothiazole based small molecule inhibitors of p56(lck) was prepared to elucidate their structure-activity relationships (SAR), selectivity and cell activity in the T-cell proliferation assay. BMS-350751 (2) and BMS-358233 (3) are identified as potent Lck inhibitors with excellent cellular activities against T-cell proliferation.     

Identification of the components controlling inactivation of voltage-gated Ca2+ channels

Ca(2+)-dependent inactivation (CDI) of L-type voltage-gated Ca(2+) channels limits Ca(2+) entry into neurons, thereby regulating numerous cellular events. Here we present the isolation and purification of the Ca(2+)-sensor complex, consisting of calmodulin (CaM) and part of the channel's pore-forming alpha(1C) subunit, and demonstrate the Ca(2+)-dependent conformational shift that underlies inactivation. Dominant-negative CaM mutants that prevent CDI block the sensor's Ca(2+)-dependent conformational change. We show how Ile1654 in the CaM binding IQ motif of alpha(1C) forms the link between the Ca(2+) sensor and the downstream inactivation machinery, using the alpha(1C) EF hand motif as a signal transducer to activate the putative pore-occluder, the alpha(1C) I-II intracellular linker.     

The formation of phosphatidylcholine oxidation products by stimulated phagocytes

Phagocytic cells produce a variety of oxidants as part of the immune defence, which react readily both with proteins and lipids, and could contribute to the oxidation of low density lipoprotein in atherosclerosis. We have investigated the oxidation of phospholipid vesicles by neutrophils and mononuclear cells, to provide a model of lipid oxidation in the absence of competing protein. Phorbol 12-myristate 13-acetate-stimulated neutrophils were incubated with phospholipid vesicles containing dipalmitoyl phosphatidylcholine, palmitoyl-arachidonoyl phosphatidylcholine (PAPC) and stearoyl-oleoyl phosphatidylcholine, before extraction of the lipids for analysis by HPLC coupled to electrospray mass spectrometry. The formation of monohydroperoxides (814 m/z) and bishydroperoxides (846 m/z) of PAPC was observed. However, the major oxidized product occurred at 828 m/z, and was identified as 1-palmitoyl-2-(5,6-epoxyisoprostane E₂)-sn-glycero-3-phosphocholine. These products were also formed in incubations where the neutrophils were replaced by mononuclear cells, and the amounts produced per million cells were similar. These results show that following oxidative attack by phagocytes stimulated by PMA, intact phospholipid oxidation products can be detected. The identification of an epoxyisoprostane phospholipid as the major product of phagocyte-induced phospholipid oxidation is novel, and in view of its inflammatory properties has implications for phagocyte involvement in atherogenesis.     

Efficient intracellular delivery of oligonucleotides formulated in folate receptor-targeted lipid vesicles

In this study, a novel lipid vector has been developed for targeted delivery of oligodeoxynucleotides (ODN) to tumors that overexpress folate receptor. This is based on a method developed by Semple et al. (1), which utilizes an ionizable aminolipid (1,2-dioleoyl-3-(dimethylammonio)propane, DODAP) and an ethanol-containing buffer system for encapsulating large quantities of polyanionic ODN in lipid vesicles. Folate is incorporated into the lipid vesicles via a distearoylphosphatidylethanolamine-poly(ethylene glycol) (DSPE-PEG) spacer. These vesicles are around 100-200 nm in diameter with an ODN entrapment efficiency of 60-80%. Folate mediated efficient delivery of ODN to KB cells that overexpress folate receptor. Uptake of folate-targeted lipidic ODN by KB cells is about 8-10-fold more efficient than that of lipidic ODN without a ligand or free ODN. This formulation is resistant to serum. Thus, targeted delivery of ODN via this novel lipid vector may have potential in treating tumors that overexpress folate receptors.     

Endemic goitre: a research protocol elaboration for eradication

The iodine deficiency (ID), which affects 1 person out of 6, is relatively neglected by the responsible of Public Health Service, particularly in developing countries. Consequences of ID are far from being negligible: mental retardation, hypofertility, hyperplasia, carcinoma, early ageing and, in very exposed areas, endemic cretinism. Nevertheless, eradication is easy and cheap but it requires rigorous protocols and control of results. The elaboration of these protocols is complex because it must be adapted to environment, population and financial possibilities of concerned countries. Based on our experience in this field, we propose a combined protocol, between the Public Health too liberal approach and that of too expensive research, which can be adapted to several situations.