Instaneous changes in the radial artery blood flow under different physiological conditions

Using a Doppler pulse flowmeter we measured the blood flow in the radial artery at rest and during physical exercise and various other stimuli (arithmetical calculations, electrical stimulation, deep inspiration). The mean resting flow in the radial artery was 0.66 ml/s. Every stimulus was instantaneously followed by a drop in the blood flow to a minimum value; there was no significant differences between these values. The results demonstrate that the new, non-invasive apparatus can be used to study quick changes in the blood flow not detected by routine non-invasive methods.     

Capillary filtration during postischaemic hyperaemia in human limbs.

The rate of capillary filtration after 5 minutes' ischaemia of the lower limbs was studied in man by the venous occlusive plethysmography method. The measured values were 3 times lower on an average than the control values. Comparison of the plethysmographic curves with isotope recordings after the intravenous administration of In-113m shows that volume changes induced by venous occlusion during reactive hyperaemia take place mainly intravascularly and do not allow any conclusions to be drawn on changes in blood-tissue fluid shifts.     

Adsorption of uni and divalent cations to planar bilayer membranes containing sulphatides or phosphatidylserine

It has been postulated that sulphatides may be the K+ binding site of the sodium pump. In order to test this hypothesis we studied the binding of K+ to bilayer membranes containing sulphatides or phosphatidylserine. The adsorption constants of Na+, K+ and Ca2+ to planar bilayers containing these acidic lipids were determined from changes in the electrostatic potential at the membrane surface. Our results indicate that univalent cations adsorb weakly to both lipids and Ca2+ binds more strongly. The sequence of ion binding was Ca2+ greater than Na+ greater than K+. These results indicate that K+ does not bind specifically to sulphatides or phosphatidylserine and rule out the proposal that sulphatides by themselves provide the K+ binding site of the sodium pump.     

Enhancer-site downstream binding protein activity is enriched in rat tissues that express the class I alcohol dehydrogenase gene.

The activity of the rat class I alcohol dehydrogenase (ADH) is enriched in certain tissues including the liver, intestine and testis. The tissue-specific expression of the gene encoding ADH in the rat was studied and found to closely correlate with tissue isozymic activity. A factor designated enhancer-site downstream binding protein (EDBP) was recently identified in the rat liver and found to interact with the proximal promoter of the class I ADH gene. The distribution of EDBP in nuclear extracts obtained from various tissues was examined based on its sequence-specific DNA binding property and found to correlate with tissue ADH expression. These findings suggest that EDBP is potentially a positive regulatory factor which is involved in controlling the tissue-specific expression of the ADH gene.     

Hemispheric asymmetries in cortical electrical activity during sleep. I

The hypothesis of a predominance of the right hemisphere in stage REM as compared to NREM has been tested through a spectral analysis of the EEG recorded from left (T3) and right (T4) temporal sites in 5 young healthy right-handed male subjects. Variations in the asymmetry coefficient R - L/R + L in different sleep stages have been analyzed by one way ANOVAs and Sheffé's tests. The hypothesis of a progressive increase in left hemisphere activity throughout different REM cycles as one approaches final awakenings have been investigated by comparing variations in the asymmetry coefficient for epochs of REM and stage 2 NREM sampled in different phases of the REM cycle. EEG results do not support either the hypothesized stage dependent or cycle dependent variation in EEG activity during sleep. We question whether variations in EEG amplitude and synchronization can be used as indices of hemispheric asymmetries during sleep.     

Melanoma RBPome identification reveals PDIA6 as an unconventional RNA-binding protein involved in metastasis

RNA-binding proteins (RBPs) have been relatively overlooked in cancer research despite their contribution to virtually every cancer hallmark. Here, we use RNA interactome capture (RIC) to characterize the melanoma RBPome and uncover novel RBPs involved in melanoma progression. Comparison of RIC profiles of a non-tumoral versus a metastatic cell line revealed prevalent changes in RNA-binding capacities that were not associated with changes in RBP levels. Extensive functional validation of a selected group of 24 RBPs using five different in vitro assays unveiled unanticipated roles of RBPs in melanoma malignancy. As proof-of-principle we focused on PDIA6, an ER-lumen chaperone that displayed a novel RNA-binding activity. We show that PDIA6 is involved in metastatic progression, map its RNA-binding domain, and find that RNA binding is required for PDIA6 tumorigenic properties. These results exemplify how RIC technologies can be harnessed to uncover novel vulnerabilities of cancer cells.     

Purification, Characterization, and Functional Role of a Novel Extracellular Protease from Pleurotus ostreatus

A new extracellular protease (PoSl; Pleurotus ostreatus subtilisin-like protease) from P. ostreatus culture broth has been purified and characterized. PoSl is a monomeric glycoprotein with a molecular mass of 75 kDa, a pI of 4.5, and an optimum pH in the alkaline range. The inhibitory profile indicates that PoSl is a serine protease. The N-terminal and three tryptic peptide sequences of PoSl have been determined. The homology of one internal peptide with conserved sequence around the Asp residue of the catalytic triad in the subtilase family suggests that PoSl is a subtilisin-like protease. This hypothesis is further supported by the finding that PoSl hydrolysis sites of the insulin B chain match those of subtilisin. PoSl activity is positively affected by calcium. A 10-fold decrease in the K_m value in the presence of calcium ions can reflect an induced structural change in the substrate recognition site region. Furthermore, Ca²⁺ binding slows PoSl autolysis, triggering the protein to form a more compact structure. These effects have already been observed for subtilisin and other serine proteases. Moreover, PoSl protease seems to play a key role in the regulation of P. ostreatus laccase activity by degrading and/or activating different isoenzymes.     

Purification and Characterization of an Endopolygalacturonase Produced by Sclerotinia Sclerotiorum

An endopolygalacturonase (endo-PG), was purified from the culture medium of a local isolate of Sclerotinia sclerotiorum with ammonium sulphate precipitation, cation exchange chromatography and gel filtration. The purified endo-PG had a molecular mass of approximately 18 kDa estimated by gel filtration. The isoelectric point was determined by isoelectric focusing to be approximately 8, suggesting that PG II possesses a net positive charge at physiological pHs. The pH optimum for the enzyme was at pH 4.5. The endo-PG showed essentially the same affinity for pectin and polygalacturonic acid as substrates. This revised version was published online in July 2006 with corrections to the Cover Date.