Signal-regulatory protein is selectively expressed by myeloid and neuronal cells

Signal-regulatory proteins (SIRP) are transmembrane glycoproteins with three extracellular Ig-like domains, closely related to Ag receptors Ig, TCR, and MHC, and a cytoplasmic domain with two immunoreceptor with tyrosine-based inhibition motifs that can interact with src homology 2 domain-containing phosphatases. SIRP have previously been shown to inhibit signaling through receptor tyrosine kinases, but their physiologic function is unknown. Here we demonstrate by expression cloning that the mAbs ED9, ED17, and MRC-OX41 recognize rat SIRP. In addition, we show for the first time that rat SIRP is selectively expressed by myeloid cells (macrophages, monocytes, granulocytes, dendritic cells) and neurons. Moreover, SIRP ligation induces nitric oxide production by macrophages. This implicates SIRP as a putative recognition/signaling receptor in both immune and nervous systems.     

Degenerate perturbations of protein structure as the mechanism of anaesthetic action

The interaction of the n-alkanols with lipid bilayers and excitable membranes shows that there is no simple correlation between conduction block and any of the perturbations of bilayer structure currently proposed as unitary mechanisms of local anaesthetic action. We propose instead that the n-alkanols act by direct interaction with target proteins to cause perturbations which depend directly on the precise structure of the alcohol.     

In situ 31P nuclear magnetic resonance for observation of polyphosphate and catabolite responses of chemostat-cultivated Saccharomyces cerevisiae after alkalinization

The proposed pH buffering and phosphagenic functions of polyphosphate were investigated by subjecting chemostat-cultivated Saccharomyces cerevisiae to alkalinization (NaOH addition) and anaerobiosis. The subsequent changes in intracellular phosphate-containing species were observed in situ by nuclear magnetic resonance (NMR) spectroscopy by using the NMR cultivator we developed. For the alkalinization experiments, changes in catabolite secretion were also measured in parallel experiments. Additionally, a range of potential neutralization capacity was investigated: a dilute culture and concentrated cultures with low or high polyphosphate content. The concentrated cultures displayed increased cytosolic pH and rapid polyphosphate degradation to small chains. The pH changes and extent of polyphosphate degradation depended inversely on initial polyphosphate content. The dilute culture restored extracellular pH rapidly and secreted acetate. The concentrated culture with low polyphosphate reserves also secreted acetate. In contrast to the alkalinization-induced polyphosphate dynamics, anaerobiosis resulted in the complete hydrolysis of polyphosphate to P(i), as opposed to small chains, and reduced cytosolic pH. The results and calculations suggest that the bulk of NMR-observable polyphosphate (vacuolar) degradation to short polymers conceivably contributes to neutralizing added alkalinity. In other circumstances, such as anaerobiosis, degradation serves other functions, such as phosphorylation potential regulation.     

Comparison of respirable coal mine dust concentrations measured with an MRE and a newly-developed, two-stage impactor sampler

The design and laboratory evaluation of a two-stage aerosol sampler using an impaction plate for removing particles above 10 micron, has been reported. The unit was developed to provide an alternative to the two-stage sampling head used on approved coal mine personal respirable dust samplers. The new device offers the potential of increasing the analytical accuracy of samples, and of providing a device more suitable to the mining community for use in their mandated dust sampling program. This paper describes the underground sampling program conducted to establish the factor for converting respirable dust concentrations measured with this device to equivalent concentrations measured with an Isleworth 113A gravimetric dust sampler (MRE). This study demonstrated that the use of the impactor sampling head provides a viable alternative to the currently used sampling head. The results showed that comparative measurements could be linearly related for MRE dust measurements ranging from 0.5 to 5.5 mg/m3. The factor determined for converting measurements made with the new head to equivalent MRE measurements was approximately 0.5.