The physico-chemical mechanism of mediated transport. I. Facilitated diffusion

On the basis of the currently accepted model for the cell membrane structure, a physico-chemical model for mediated transport is developed and solved for the case of polar non-electrolyte migration through the cell membrane. The model considers the interstitial space defined by the transport protein subunits to be the migration pathway for polar solutes. A Langmuir-type adsorption equilibrium is assumed at the interfaces and a multicomponent diffusion mechanism of solute and water is postulated within the migration pathway, where the polar residues of the transport protein represent another component of the system. Membrane selectivity is governed by the adsorption constants, which are shown to affect strongly the kinetics of transport. Isosmotic transport and the volume change of the cell are important features incorporated in the model, which is shown to fulfill the peculiar properties of facilitated diffusion systems. It is concluded that the same type of pathway can be used for the transport of other polar solutes through existing or induced hydrophilic channels, for which a similar approach is suggested.     

Maladaptive innate immune training of myelopoiesis links inflammatory comorbidities

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Studies on the possible biological effects of 50 Hz electric and/or magnetic fields: Evaluation of some glycolytic enzymes,glycolytic flux,energy and oxido-reductive potentials in human erythrocytes exposed in vitro to power frequency fields

An attempt has been made to understand whether 50 Hz electric and magnetic fields (EMFs) are involved in producing bioeffects by exposing human erythrocytes in vitro. The study evaluated some key glycolytic enzymes, glucose consumption, lactate production, energy charge, 2,3-diphosphoglycerate, and reduced glutathione levels. all of which are biochemical parameters significant to erythrocyte function. Cells exposed to individual or superimposed EMFs have not shown any significant difference compared with the controls. © 1993 Wiley-Liss. Inc.     

Norditerpene dilactones from Podocarpus saligna

Rimuene and nubigenol have been identified in Podocarpus saligna for the first time, and the structures of three new norditerpene dilactones, salignones K, L and M, isolated from this species have been elucidated.     

Isolation and characterization of catechol oxidase from Solanum melongena

Catechol oxidase was distributed in soluble and particulate fractions of Solanum melongena. The purified preparation appears to be homogeneous by polyacrylamide gel electrophoresis. The enzyme shows two pH maxima—with catechol, 6.5 and 7.5; and with dopa, 6.5 and 7.9. The latent form of the enzyme does not occur in S. melongena. The preparation resembles the enzyme from other sources in substrate specificity towards various mono- and diphenols, having a higher affinity for catechol than dopa; this tendency increases on purification. The cresolase activity decreases with purification and a lag period with p-cresol is observed. The oxidation of mono- and diphenols is inhibited by ascorbic acid, sulphydryl compounds and chelating agents.     

Genetic information improves the prediction of major adverse cardiovascular events in the GENEMACOR population

The inclusion of a genetic risk score (GRS) can modify the risk prediction of coronary artery disease (CAD), providing an advantage over the use of traditional models. The predictive value of the genetic information on the recurrence of major adverse cardiovascular events (MACE) remains controversial. A total of 33 genetic variants previously associated with CAD were genotyped in 1587 CAD patients from the GENEMACOR study. Of these, 18 variants presented an hazard ratio >1, so they were selected to construct a weighted GRS (wGRS). MACE discrimination and reclassification were evaluated by C-Statistic, Net Reclassification Index and Integrated Discrimination Improvement methodologies. After the addition of wGRS to traditional predictors, the C-index increased from 0.566 to 0.572 (p=0.0003). Subsequently, adding wGRS to traditional plus clinical risk factors, this model slightly improved from 0.620 to 0.622 but with statistical significance (p=0.004). NRI showed that 17.9% of the cohort was better reclassified when the primary model was associated with wGRS. The Kaplan-Meier estimator showed that, at 15-year follow-up, the group with a higher number of risk alleles had a significantly higher MACE occurrence (p=0.011). In CAD patients, wGRS improved MACE risk prediction, discrimination and reclassification over the conventional factors, providing better cost-effective therapeutic strategies.     

Fine structural studies of rat adrenal cortices following prostaglandin administration

Summary Histological and fine structural studies of adrenal cortices were performed on male Sprague-Dawley rats which had been given intravenous injections of prostaglandin E₁ or E₂. It was found that there were increased numbers of intracellular lipid droplets, free ribonucleoprotein particles, cholesterol ester clefts and coated vesicles of both the small and large varieties. A reorganization of the internal mitochondrial membranes and the appearance of protrusions of parenchymal cytoplasm into the sinusoidal lumina accompanied by vasodilation were also observed. These alterations are not typical of those observed following exogenous ACTH administration and are therefore considered to be prostaglandin-induced. Supported in part by N.I.H. Grant AM-09561.