Identification of risk factors of severe hypersensitivity reactions in general anaesthesia

Background

Hypersensitivity reactions to anaesthetic agents are rare but often severe, with a mortality ranging from 4 to 9% in IgE-mediated events. Identification of the risk factors may contribute to limit the incidence of these reactions. The aim of our study was to search for possible risk factors of severe perioperative hypersensitivity reactions in our study population.

Methods

For this study we retrospectively reviewed data from 193 patients who experienced drug hypersensitivity reactions during general anaesthesia. The diagnostic protocol consisted of 1) history of the reaction, 2) measurement of serum baseline tryptase and specific IgE-assays for latex, beta-lactams and succinylcholine, 3) skin tests for the agents listed in the anaesthesia chart and for others likely to be safe for future use, latex, and others medications administered during the perioperative period (i.e. antibiotics), 4) subdivision of our patients on the basis of two criteria: a) grade of severity of clinical reactions according to the Ring and Messmer classification; b) results of skin tests and/or serum specific IgE-assays.

Results

One hundred of 193 patients had reactions of grade I, 32/193 patients had reactions of grade II, 55/193 patients had reactions of grade III and 6/193 patients had reactions of grade IV. A diagnosis of IgE-mediated reaction was established in 55 cases (28.50%); the most common causes were neuromuscular blocking agents, followed by latex and beta-lactams. Severe reactions were associated with older age (p = 0.025), asthma (p = 0.042), history of hypertension (p = 0.001), intake of serum angiotensin converting enzyme inhibitor medication (p = 0.012) or serum angiotensin II antagonist (p = 0.033), higher levels of basal tryptase (p = 0.0211). Cardiovascular symptoms (p = 0.006) and history of hypersensitivity to antibiotics (p = 0.029) were more frequently reported in IgE-mediated reactions.

Conclusions

We confirmed the relevance of several clinical features as risk factors for anaphylactic reactions induced by anaesthetic agents: older age, asthma, hypertension and antihypertensive drugs. We observed increased levels of serum basal tryptase in severe reactions: this finding may signify that this biomarker is useful for the identification of patients at risk.

Electronic supplementary material

The online version of this article (doi:10.1186/s12948-015-0017-9) contains supplementary material, which is available to authorized users.     

Variegated silencing through epigenetic modifications of a large Xq region in a case of balanced X;2 translocation with Incontinentia Pigmenti-like phenotype

Molecular mechanisms underlying aberrant phenotypes in balanced X;autosome translocations are scarcely understood. We report the case of a de novo reciprocal balanced translocation X;2(q23;q33) presenting phenotypic alterations highly suggestive of Incontinentia Pigmenti (IP) syndrome, a genodermatosis with abnormal skin pigmentation and neurological failure, segregating as X-linked dominant disorder. Through molecular studies, we demonstrated that the altered phenotype could not be ascribed to chromosome microdeletions or to XIST-mediated inactivation of Xq24-qter. Interestingly, we found that the Xq24-qter region, which translocated downstream of the heterochromatic band 2q34, undergoes epigenetic silencing mediated by DNA methylation and histone alterations. Among the downregulated genes, we found the inhibitor of kappa light polypeptide gene enhancer in B cells, kinase gamma (IKBKG/NEMO), the causative gene of IP. We hypothesize that a mosaic functional nullisomy of the translocated genes, through a Position Effect Variegation-like heterochromatization, might be responsible for the proband's phenotypic anomalies. Partial silencing of IKBKG may be responsible for the skin anomalies observed, thereby mimicking the IP pathological condition. In addition to its clinical relevance, this paper addresses fundamental issues related to the chromatin status and nuclear localization of a human euchromatic region translocated proximally to heterochromatin. In conclusion, the study provides new insight into long-range gene silencing mechanisms and their direct impact in human disease.     

SPR‐based plastic optical fibre biosensor for the detection of C‐reactive protein in serum

A plastic optical fibre biosensor based on surface plasmon resonance for the detection of C‐reactive protein (CRP) in serum is proposed. The biosensor was integrated into a home‐made thermo‐stabilized microfluidic system that allows avoiding any thermal and/or mechanical fluctuation and maintaining the best stable conditions during the measurements. A working range of 0.006–70 mg L^–1 and a limit of detection of 0.009 mg L^–1 were achieved. These results are among the best compared to other SPR‐based biosensors for CRP detection, especially considering that they were achieved in a real and complex medium, i.e. serum. In addition, since the sensor performances satisfy those requested in physiologically‐relevant clinical applications, the whole biosensing platform could well address high sensitive, easy to realize, real‐time, label‐free, portable and low cost diagnosis of CRP for future lab‐on‐a‐chip applications.

3D sketch (left) of the thermo‐stabilized home‐made flow cell developed to house the SPR‐based plastic optical fibre biosensor. Exemplary response curve (shift of the SPR wavelength versus time) of the proposed biosensor (right) for the detection of C‐reactive protein in serum.     

Population genetics of Vibrio vulnificus: identification of two divisions and a distinct eel-pathogenic clone

Genetic relationships among 62 Vibrio vulnificus strains of different geographical and host origins were analyzed by multilocus enzyme electrophoresis (MLEE), random amplification of polymorphic DNA (RAPD), and sequence analyses of the recA and glnA genes. Out of 15 genetic loci analyzed by MLEE, 11 were polymorphic. Cluster analysis identified 43 distinct electrophoretic types (ETs) separating the V. vulnificus population into two divisions (divisions I and II). One ET (ET 35) included all indole-negative isolates from diseased eels worldwide (biotype 2). A second ET (ET 2) marked all of the strains from Israel isolated from patients who handled St. Peter's fish (biotype 3). RAPD analysis of the 62 V. vulnificus isolates identified 26 different profiles separated into two divisions as well. In general, this subdivision was comparable (but not identical) to that observed by MLEE. Phylogenetic analysis of 543 bp of the recA gene and of 402 bp of the glnA gene also separated the V. vulnificus population into two major divisions in a manner similar to that by MLEE and RAPD. Sequence data again indicated the overall subdivision of the V. vulnificus population into different biotypes. In particular, indole-negative eel-pathogenic isolates (biotype 2) on one hand and the Israeli isolates (biotype 3) on the other tended to cluster together in both gene trees. None of the methods showed an association between distinct clones and human clinical manifestations. Furthermore, except for the Israeli strains, only minor clusters comprising geographically related isolates were observed. In conclusion, all three approaches (MLEE, RAPD, and DNA sequencing) generated comparable but not always equivalent results. The significance of the two divisions (divisions I and II) still remains to be clarified, and a reevaluation of the definition of the biotypes is also needed.     

MCU proteins dominate in vivo mitochondrial Ca2+ uptake in Arabidopsis roots

Ca²⁺ signaling is central to plant development and acclimation. While Ca²⁺-responsive proteins have been investigated intensely in plants, only a few Ca²⁺-permeable channels have been identified, and our understanding of how intracellular Ca²⁺ fluxes is facilitated remains limited. Arabidopsis thaliana homologs of the mammalian channel-forming mitochondrial calcium uniporter (MCU) protein showed Ca²⁺ transport activity in vitro. Yet, the evolutionary complexity of MCU proteins, as well as reports about alternative systems and unperturbed mitochondrial Ca²⁺ uptake in knockout lines of MCU genes, leave critical questions about the in vivo functions of the MCU protein family in plants unanswered. Here, we demonstrate that MCU proteins mediate mitochondrial Ca²⁺ transport in planta and that this mechanism is the major route for fast Ca²⁺ uptake. Guided by the subcellular localization, expression, and conservation of MCU proteins, we generated an mcu triple knockout line. Using Ca²⁺ imaging in living root tips and the stimulation of Ca²⁺ transients of different amplitudes, we demonstrated that mitochondrial Ca²⁺ uptake became limiting in the triple mutant. The drastic cell physiological phenotype of impaired subcellular Ca²⁺ transport coincided with deregulated jasmonic acid-related signaling and thigmomorphogenesis. Our findings establish MCUs as a major mitochondrial Ca²⁺ entry route in planta and link mitochondrial Ca²⁺ transport with phytohormone signaling.

Monitoring of subcellular Ca²⁺ dynamics in living Arabidopsis roots reveals that MCU proteins provide the dominant mitochondrial Ca²⁺ uptake mechanism in vivo.     

Activation of phospholipase A2 and MAP kinases by oxidized low-density lipoproteins in immortalized GP8.39 endothelial cells

In immortalized rat brain endothelial cells (GP8.39), we have previously shown that oxidized LDL (oxLDL), after 24-h treatment, stimulates arachidonic acid release and phosphatidylcholine hydrolysis by activation of cytosolic phospholipase A₂ (cPLA₂). A putative role for MAPKs in this process has emerged. Here, we studied the contribution of Ca²⁺-independent phospholipase A₂ (iPLA₂), and the role of the MAP kinase family as well as both cPLA₂ and iPLA₂ mRNA expression by RT-PCR in oxLDL toxicity to GP8.39 cells in vitro. The activation of extracellular signal-regulated kinases ERK1/2, p38 and c-Jun NH₂-terminal kinase (JNK) was assessed with Western blotting and kinase activity assays. iPLA₂ activity, which was found as a membrane-associated enzyme, was more stimulated by oxLDL compared with native LDL. The phosphorylation of ERK1/2, p38 and JNKs was also significantly enhanced in a dose-dependent manner. PD98059, an ERK inhibitor, SB203580, a p38 inhibitor, and SP600125, an JNK inhibitor, abolished the stimulation of all three members of the MAPK family by oxLDL. Confocal microscopy analysis and subcellular fractionation confirmed either an increase in phosphorylated form of ERKs, p38 and JNKs, or their nuclear translocation upon activation. A strong inhibition of MAPK activation was also observed when endothelial cells were treated with GF109203X, a PKC inhibitor, indicating the important role of both PKC and all three MAPKs in mediating the maximal oxLDL response. Finally, compared with samples untreated or treated with native LDL, treatment with oxLDL (100 μM hydroperoxides) for 24 h significantly increased the levels of constitutively expressed iPLA₂ protein (by 5.1-fold) and mRNA (by 3.1-fold), as well as cPLA₂ protein (by 4.4-fold) and mRNA (by 1.5-fold). Together, these data link the stimulation of PKC–ERK–p38–JNK pathways and PLA₂ activity by oxLDL to the prooxidant mechanism of the lipoprotein complex, which may initially stimulate the endothelial cell reaction against noxious stimuli as well as metabolic repair, such as during inflammation and atherosclerosis.