Laboratory monitoring of patients treated with antihypertensive drugs and newly exposed to non steroidal anti-inflammatory drugs: a cohort study

Background

Drug-Drug Interactions between Non Steroidal Anti-Inflammatory Drugs (NSAIDs) and Angiotensin Converting Enzyme Inhibitors (ACEIs), Angiotensin Receptor Blocker (ARBs) or diuretics can lead to renal failure and hyperkalemia. Thus, monitoring of serum creatinine and potassium is recommended when a first dispensing of NSAID occur in patients treated with these drugs.

Methods

We conducted a pharmacoepidemiological retrospective cohort study using data from the French Health Insurance Reimbursement Database to evaluate the proportion of serum creatinine and potassium laboratory monitoring in patients treated with ACEI, ARB or diuretic and receiving a first dispensing of NSAID. We described the first dispensing of NSAID among 3,500 patients of a 4-year cohort (6,633 patients treated with antihypertensive drugs) and analyzed serum creatinine and potassium laboratory monitoring within the 3 weeks after the first NSAID dispensing.

Results

General Practitioners were the most frequent prescribers of NSAIDs (85.5%, 95% CI: 84.3–86.6). The more commonly prescribed NSAIDs were ibuprofen (20%), ketoprofen (15%), diclofenac (15%) and piroxicam (12%). Serum creatinine and potassium monitoring was 10.7% (95% CI: 9.5–11.8) in patients treated by ACEIs, ARBs or diuretics. Overall, monitoring was more frequently performed to women aged over 60, treated with digoxin or glucose lowering drugs, but not to patients treated with ACEIs, ARBs or diuretics. Monitoring was more frequent when NSAIDs'' prescribers were cardiologists or anesthesiologists.

Conclusion

Monitoring of serum creatinine and potassium of patients treated with ACEIs, ARBs or diuretics and receiving a first NSAID dispensing is insufficiently performed and needs to be reinforced through specific interventions.     

Stimulation of Cortical Myosin Phosphorylation by p114RhoGEF Drives Cell Migration and Tumor Cell Invasion

Actinomyosin activity is an important driver of cell locomotion and has been shown to promote collective cell migration of epithelial sheets as well as single cell migration and tumor cell invasion. However, the molecular mechanisms underlying activation of cortical myosin to stimulate single cell movement, and the relationship between the mechanisms that drive single cell locomotion and those that mediate collective cell migration of epithelial sheets are incompletely understood. Here, we demonstrate that p114RhoGEF, an activator of RhoA that associates with non-muscle myosin IIA, regulates collective cell migration of epithelial sheets and tumor cell invasion. Depletion of p114RhoGEF resulted in specific spatial inhibition of myosin activation at cell-cell contacts in migrating epithelial sheets and the cortex of migrating single cells, but only affected double and not single phosphorylation of myosin light chain. In agreement, overall elasticity and contractility of the cells, processes that rely on persistent and more constant forces, were not affected, suggesting that p114RhoGEF mediates process-specific myosin activation. Locomotion was p114RhoGEF-dependent on Matrigel, which favors more roundish cells and amoeboid-like actinomyosin-driven movement, but not on fibronectin, which stimulates flatter cells and lamellipodia-driven, mesenchymal-like migration. Accordingly, depletion of p114RhoGEF led to reduced RhoA, but increased Rac activity. Invasion of 3D matrices was p114RhoGEF-dependent under conditions that do not require metalloproteinase activity, supporting a role of p114RhoGEF in myosin-dependent, amoeboid-like locomotion. Our data demonstrate that p114RhoGEF drives cortical myosin activation by stimulating myosin light chain double phosphorylation and, thereby, collective cell migration of epithelial sheets and amoeboid-like motility of tumor cells.     

Cellular SR-BI and ABCA1-mediated cholesterol efflux are gender-specific in healthy subjects

We evaluated the impact of gender differences in both the quantitative and qualitative features of HDL subspecies on cellular free cholesterol efflux through the scavenger receptor class B type I (SR-BI), ABCA1, and ABCG1 pathways. For that purpose, healthy subjects (30 men and 26 women) matched for age, body mass index, triglyceride, apolipoprotein A-I, and high density lipoprotein-cholesterol (HDL-C) levels were recruited. We observed a significant increase (+14%; P < 0.03) in the capacity of whole sera from women to mediate cellular free cholesterol efflux via the SR-BI-dependent pathway compared with sera from men. Such enhanced efflux capacity resulted from a significant increase in plasma levels of large cholesteryl ester-rich HDL2 particles (+20%; P < 0.04) as well as from an enhanced capacity (+14%; P < 0.03) of these particles to mediate cellular free cholesterol efflux via SR-BI. By contrast, plasma from men displayed an enhanced free cholesterol efflux capacity (+31%; P < 0.001) via the ABCA1 transporter pathway compared with that from women, which resulted from a 2.4-fold increase in the plasma level of prebeta particles (P < 0.008). Moreover, in women, SR-BI-mediated cellular free cholesterol efflux was significantly correlated with plasma HDL-C (r = 0.72, P < 0.0001), whereas this relationship was not observed in men. In conclusion, HDL-C level may not represent the absolute indicator of the efficiency of the initial step of the reverse cholesterol transport.     

Production of biologically active forms of recombinant hepcidin, the iron-regulatory hormone

Hepcidin is a liver produced cysteine-rich peptide hormone that acts as the central regulator of body iron metabolism. Hepcidin is synthesized under the form of a precursor, prohepcidin, which is processed to produce the biologically active mature 25 amino acid peptide. This peptide is secreted and acts by controlling the concentration of the membrane iron exporter ferroportin on intestinal enterocytes and macrophages. Hepcidin binds to ferroportin, inducing its internalization and degradation, thus regulating the export of iron from cells to plasma. The aim of the present study was to develop a novel method to produce human and mouse recombinant hepcidins, and to compare their biological activity towards their natural receptor ferroportin. Hepcidins were expressed in Escherichia coli as thioredoxin fusion proteins. The corresponding peptides, purified after cleavage from thioredoxin, were properly folded and contained the expected four-disulfide bridges without the need of any renaturation or oxidation steps. Human and mouse hepcidins were found to be biologically active, promoting ferroportin degradation in macrophages. Importantly, biologically inactive aggregated forms of hepcidin were observed depending on purification and storage conditions, but such forms were unrelated to disulfide bridge formation.     

Interaction of Clostridium perfringens iota-toxin with lipid bilayer membranes. Demonstration of channel formation by the activated binding component Ib and channel block by the enzyme component Ia.

The interaction between model lipid membranes and the binding component (Ib) of the ADP-ribosylating iota-toxin of Clostridium perfringens was studied in detail. Ib had to be activated by trypsin to result in channel formation in artificial lipid bilayers. The channels formed readily by Ib had a small single-channel conductance of about 85 picosiemens in 1 m KCl. Channel function was blocked in single-channel and multichannel experiments by the enzymatic component Ia in a pH-dependent manner. The strong Ia-mediated channel block of Ib occurred only when the pH was at least lowered to pH 5.6. The single-channel conductance showed a linear dependence on the bulk aqueous KCl concentration, which indicated that the channel properties were more general than specific. Zero current membrane potential measurements suggested the Ib channel has an approximately 6-fold higher permeability for potassium ions than for chloride. The selectivity ratio changed for salts composed of cations and anions of different mobility in the aqueous phase, again suggesting that Ib formed a water-filled general diffusion pore. Asymmetric addition of activated Ib to lipid bilayer membranes resulted in an asymmetric voltage dependence, indicating its full orientation within the membrane. Titration experiments with chloroquine and different tetraalkylammonium ions suggested that the Ib channel was blocked by these compounds but had only a weak affinity to them. In vivo measurements using Vero cells demonstrate that chloroquine and related molecules also did not efficiently block intoxication of the cells by iota-toxin. The possible role of Ib in the translocation of iota-toxin across the target cell membrane is discussed.     

Physico-chemical investigation of the mode of binding of the alkaloids 5,6-dihydroflavopereirine and sempervirine with DNA

The mode of binding of 5,6-dihydroflavopereirine and sempervirine to DNA has been investigated by absorption spectrophotometry, circular and electric linear dichroism, fluorescence and fluorescence polarization, viscosity increase of sonicated linear DNA and circular DNA unwinding. Although the spectroscopic properties of both compounds bound to DNA resembled those reported in our previous study of DNA complexes with two other alkaloids, and observed with planar intercalating compounds, only sempervirine was able to unwind circular DNA. The latter drug however showed signs characteristic of aggregation at the surface of the polyion. The differences between the behaviours of the four alkaloids so far investigated by us are interpreted on the basis of different extent of penetration of the chromophore ring into the DNA helix.     

Site of synthesis of geranylgeraniol derivatives in intact spinach chloroplasts

Chloroplasts isolated from fully developed spinach leaves and incubated in the presence of isopentenyl pyrophosphate were able to synthesize rapidly geranylgeranyl chlorophyll a and geranylgeraniol.The biosynthesis of the geranylgeraniol derivatives from isopentenyl pyrophosphate is a compartimentalized process. The membrane fractions (thylakoid and envelope membranes) were essentially unable to synthesize geranylgeraniol, geranylgeranyl pyrophosphate and geranylgeranyl chlorophyll a. When stromal and thylakoid fractions were combined the capacity to synthesize geranylgeranyl chlorophyll a and geranylgeraniol was restored. When stromal and envelope membrane fractions were combined the capacity to synthesize geranylgeranyl pyrophosphate and geranylgeraniol was restored. The products of the reaction were discharged inside the lipid phase of the membranes.     

Isolation and genetic mapping of Escherichia coli aminopeptidase mutants

Summary Many mutant strains devoid of aminopeptidase activity have been isolated in Escherichia coli. All of them produce cross-reacting material when tested against specific antiaminopeptidase antibody. The map position of the locus specifying this enzyme has been determined by three conjugations and two P₁ mediated transduction experiments. By analogy with Salmonella typhimurium this locus has been called pepN (Miller, 1975). Mutations in pepN are jointly transduced with fabA and pyrD at high frequency. These data and conjugation results suggest a location between 20.5 and 22.5 minutes on E. coli genetic map.     

Is E37, a major polypeptide of the inner membrane from plastid envelope,an S-adenosyl methionine-dependent methyltransferase?

Using antibodies raised against E37, one of the major polypeptides of the inner membrane from the chloroplast envelope, it has been demonstrated that a single immunologically related polypeptide was present in total protein extracts from various higher plants (monocots and dicots), in photosynthetic and non-photosynthetic tissues from young spinach plantlets, as well as in the cytoplasmic membrane from the cyanobacteria Synechococcus . This ubiquitous distribution of E37 strongly suggests that this protein plays an envelope-specific function common to all types of plastids. Comparison of tobacco and spinach E37 amino acid sequences deduced from the corresponding cDNA demonstrates that consensus motifs for S-adenosyl methionine-dependent methyltransferases are located in both sequences. This hypothesis was confirmed using a biochemical approach. It was demonstrated that E37, together with two minor spinach chloroplast envelope polypeptides of 32 and 39 kDa, can be specifically photolabeled with [³H]-S-adenosyl methionine upon UV-irradiation. Identification of E37 as a photolabeled polypeptide was established by immunoprecipitation. Furthermore, photolabeling of the three envelope polypeptides was specifically inhibited by very low concentration of S-adenosyl homocysteine, thus providing evidence for the presence within these proteins of S-adenosyl methionine- and S-adenosyl homocysteine-binding sites that were closely associated. Taken as a whole these results strongly suggest that E37 is an ubiquitous plastid envelope protein that probably has an S-adenosyl methionine-dependent methyltransferase activity. The 32 and 39 kDa envelope polypeptides probably have a similar methyltransferase activity.