Can point-of-care ultrasound predict spinal hypotension during caesarean section? A prospective observational study.

Spinal anaesthesia for elective caesarean section is associated with maternal hypotension, secondary to alteration of sympathetic tone and hypovolemia, in up to 70% of cases. Measurement of the subaortic variation in the velocity time integral (VTI) after passive leg raising allows prediction of fluid responsiveness. Our objective, in this prospective single-centre observational study, was to assess the ability of change in VTI after 45° passive leg raising to predict hypotension after spinal anaesthesia. Ultrasound measurements were performed just before elective caesarean section. Anaesthesia, intravenous coloading and prophylactic vasopressor treatment were standardised according to current guidelines. We studied 40 women. Hypotension occurred in 17 (45%) women. The area (95%CI) under the receiver operating characteristics (ROC) curve for the prediction of spinal hypotension was 0.8 (0.6-0.9; p = 0.0001). Seventeen women had a change in VTI with leg elevation ≤ 8%, which was predictive for not developing hypotension, and 11 had a change ≥ 21%, predictive for hypotension. The grey zone between 8% and 21%, with inconclusive values, included 12 women. We suggest that cardiac ultrasound provides characterisation of the risk of hypotension following spinal anaesthesia at elective caesarean section, and therefore may allow individualised strategies for prevention and management.

New insights into the natural history of hepatitis E virus infection through a longitudinal study of multitransfused immunocompetent patients in France.

Little is known about the natural history of Hepatitis E virus (HEV) infection in immunocompetent individuals. The prevalence, the course of infection and the occurrence of transmission by transfusion were investigated in multitransfused immunocompetent patients/blood donor pairs included in a longitudinal sample repository collection and followed up between 1988 and 2010. Ninety-eight subjects aged 6-89 years and suffering from acquired haemoglobinopathies were tested for HEV markers (IgM, IgG and RNA) in serial samples collected every 2 or 3 years. Eighteen patients (18.4%) were positive for HEV-IgG at baseline with a prevalence increasing from 12.5% below 26 years to 32% above 56 years. Nine patients remained IgG positive along the study and nine lost their antibodies after a mean follow-up of 7.4 years (1-22 years). One seropositive patient showed an increase of IgG level and RNA-HEV reappearance 1 year after inclusion, suggesting a reinfection and one seroconversion, probably acquired through blood transfusion was observed. This first longitudinal study including immunocompetent individuals confirms that HEV infection is common in Western Europe and that transfusion transmission occurs probably less frequently than expected. In addition, seroreversion and reinfection seem to be common. This suggests that the anti-HEV may not persist overtime naturally. However, repeat exposure to the virus related to the high prevalence of HEV infection may result in a sustainable specific IgG response.

Ultrasonographic measurement of antral area for estimating gastric fluid volume in parturients.

BACKGROUND: The aim of this prospective observational study was to assess the performance of ultrasonographic gastric antral area (GAA) to predict gastric fluid volumes of >0.4, >0.8 and >1.5 ml kg(-1), in fasted women in established labour. METHODS: A first ultrasound examination of the antrum was performed, in order to confirm gastric vacuity by using a qualitative score. Baselines GAA measurements were obtained in both supine and right lateral decubitus positions. Thereafter, parturients were allowed to drink clear fluids only. Measurement of GAA was repeated 15 min after last fluid intake, in both supine and right lateral positions. Receiver operating characteristics (ROC) curves were constructed to determine the accuracy of GAA to diagnose ingested volumes of >0.4, >0.8 and >1.5 ml kg(-1). RESULTS: Data from forty parturients were analysed. The areas under the ROC curves ranged from 80% to 86%. The cut-off value for antral area measured in supine position, to detect a volume >0.4 ml kg(-1), was 387 mm(2), with a sensitivity of 87%, a specificity of 70% and a negative predictive value of 85%. A cut-off value of 608 mm(2) predicted a fluid volume >1.5 ml kg(-1), with a specificity of 94%, a sensitivity of 75% and a negative predictive value of 92%. CONCLUSIONS: This study provides cut-off values for GAA that could be used in addition to the qualitative assessment of the antrum to define a full stomach in labouring patients.

Correlation between the promoter basal core and precore mutations and HBsAg quantification in French blood donors infected with hepatitis B virus.

Hepatitis B virus (HBV) basal core promoter (BCP) and precore (PC) mutations, HBV viral load and HBV surface antigen (HBsAg) quantitation were screened to assess correlations between these HBV markers in asymptomatic chronic hepatitis B carriers in France. From January 2006 to July 2007, 200 sera were collected from patients who were discovered to be HBsAg-positive when they volunteered to give blood. Direct sequencing of precore/core gene was used to detect A1762T/G1764A mutations in the BCP and G1896A in the PC region. HBV viral load and HBsAg were quantified with two commercials assays. The prevalence of the BCP and PC mixed/mutants were 37% and 60% respectively (P = 0.0001). HBV DNA level and HBsAg titer were significantly lower in subjects harboring the mixed/mutant PC virus compared to those infected by the wild phenotype. No significant difference was observed in HBV viral loads of blood donors infected by wild or mixed/mutant BCP viruses. Mutant or mixed PC virus was associated with male gender, HBeAb-positive status and HBV/D and HBV/E genotypes. BCP mutations were associated with age, and both HBV/A-HBV/E genotypes.The genetic properties of HBV in this cohort showed that most of the blood donors had a negative HBeAg serological status and harbored the PC mutant phenotype in combination with low levels of both HBV DNA and HBsAg. As the study was conducted in healthy subjects who could be considered as asmptomatic carriers, these results suggest a possible protective effect of the G1896A mutation against severe liver lesions.

Effects of trace elements contaminations on the larval development of Paracentrotus lividus using an innovative experimental approach.

Several experiments were performed using larvae of Paracentrotus lividus (Lamarck, 1816) in order to determine the consequences of different chronic contamination with mixtures of (i) fifteen trace elements from concentrations measured in the world ocean seawater, and (ii) seven trace elements from contamination resulting from mining. To predict the impact of increased marine pollution, higher concentrations were also used. These bioassays were conducted using spawners collected from Calvi (reference site, Corsica), and Albo (mining area, Corsica). The effects of trace elements have been studied on the entire larval development. The results show wider arms and delayed development as the number and concentration of trace elements increases. Therefore, the synergy between the different trace elements is of paramount importance with regard to the impact on organisms. Probably due to a hormesis phenomenon, larvae contaminated with seven trace elements at average concentrations developed more quickly. This work also highlighted the importance of the origin of spawners in ecotoxicological studies. To our knowledge, this is the first study to investigate the effects of such a broad combination of trace elements for chronic contamination on the entire larval stage of Paracentrotus lividus.

High levels of serum hepatitis B virus DNA in patients with 'anti-HBc alone': role of HBsAg mutants.

It remains unclear how the detection of hepatitis B core antibody (anti-HBc) in the absence of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) should be interpreted and whether all patients with this pattern need to be tested for hepatitis B virus (HBV)-DNA. This study aimed at reassessing the significance of 'anti-HBc alone' in unselected sera referred to the clinical laboratory and determining whether significant HBV viraemia can be found in this setting. Of the 6431 patients tested for HBsAg, total anti-HBc and anti-HBs in a Paris hospital over a 1-year period, 362 (5.6%) had 'anti-HBc alone' (24.8% of anti-HBc-positive patients). Only 11 of the 362 sera (3.0%) were found to be false positive. One patient was in the resolving phase of acute hepatitis B. HBV-DNA was detected in 10 of 362 (2.8%) patients, using a commercial standardized assay (threshold: 350 IU/mL). Viral loads exceeded 10(4) copies/mL in 6 of 10 patients. Mutations in the HBsAg immunodominant region were identified in seven of the viraemic patients. HBsAg was detected in only two cases when retested by one of the latest, multivalent assays. Neither human immunodeficiency virus nor hepatitis C virus serostatus distinguished between patients with and without HBV-DNA. In conclusion, 'anti-HBc alone' should be considered a risk marker for a so-called 'false occult' HBV infection with significant viraemia. Indeed, results in this hospital population indicate that a small proportion of patients with 'anti-HBc alone' have high viral loads, revealing the occurrence of infection with HBV mutants that escape detection even by multivalent HBsAg assays.

[Results of a novel real-time PCR, sequence analysis, Inno-LiPA line probe assays in the detection of hepatitis B virus G1896A precore mutation in French blood donors]. / Résultats de trois méthodes pour la détection de la mutation précore G1896A du virus de l'hépatite B chez les donneurs de sang français : PCR temps réel, séquençage et test Inno-LIPA.

AIM: To screen hepatitis B virus (HBV) genotypes and associated basal core promoter (BCP; T1762A/A1764) and precore (PC; A1896) mutations among the 100 HBV surface antigen (HBsAg) positive voluntary blood donors in France. METHODS: HBV genotypes were determined by using direct sequence analysis. Three methods were used to detect G1896A mutation: non-commercial real-time PCR (PCRTR°, line probe assay (InnoLiPA HBV PreCore, INNOGENETICS(®)) and direct sequencing of precore gene. HBV viral load was quantified with two commercial real-time PCR (COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HBV Test/Roche and Real Time HBV/M2000/Abbott). RESULTS: The mean age of donors was 30 (18-64). Patients were from Africa (42%), Europa (50%), and Asia (8%). HBV/D was the most predominant (37%) genotype followed by HBV/A (31%) and HBV/E (22%). PC and BCP mutants were found in 57% with Inno-LIPA HBV test and 59% with both PCRTR and sequencing methods. A significant difference in the viral load of blood donors with wild and PC mutants was observed with the Taqman Cobas real time PCR (3,19 Log(10) UI/ml versus 4,93 Log(10) UI/ml, p < 0.05). Precore phenotype determination was in agreement with the three PC mutation detection methods in 56% of cases. CONCLUSIONS: Non-Caucasian genotype E was present in the French blood donors. PC mutation was more common than BCP mutations in this study. As HBV infected blood donors were more often asymptomatic carriers, we could speculate that the G1896A mutation may favour the asymptomatic state, supporting previous observations.

[Genetic diversity of human erythroviruses: consequences on infectious safety of blood products and plasma derivatives]. / Conséquences de la diversité génétique des érythrovirus humains sur la sécurité infectieuse des produits sanguins labiles et des médicaments dérivés du sang.

Sequence analysis of human erythroviruses shows an organization into three genotypes; genotype 1 with B19 Parvovirus (B19 V) and 2 new genotypes with a genetic diversity markedly distinct from that of B19 V. The frequency of each genotype depends on geographic origin and population. Human erythroviruses infection can be transmitted by transfusion. In immunocompetent recipients, B19 V exposure is generally inconsequential, since a large proportion is immunized. However, such a contamination may have severe clinical outcome in not immunized patients with shortened red cell survival, in seronegative pregnant women and in immunocompromised patients. No prevention of blood transmission is currently performed, but a preventive strategy could be discussed for at-risk recipients. In plasma derivatives, B19VDNA screening is done with a threshold of 104 IU/mL. With recent data of a new classification on the human erythroviruses genotypes, DNA testing assays would be validated in accordance with genetic variability, in order to guarantee optimal safety.

[Diversity of hepatitis B virus and its consequences]. / Impact clinique, thérapeutique et diagnostique de la diversité génétique du virus de l'hépatite B.

The genetic diversity of hepatitis B virus (HBV) was defined on the basis of the characterisation of the major determinants in the antigenic loop of HBs antigen (Ag). Historically, nine subtypes were defined. Recently, based on sequence analysis, HBV genomes have been classified into eight genotypes (A-H) which present distinct geographical distributions. Genetic mutants may have a selective advantage in patients treated with passive or active immunization (hepatitis B immune globulin or vaccine). Anti-viral treatment can be responsible for the emergence of escape mutants with resistant mutations in the polymerase gene. These substitutions can lead to changes on HBsAg structure. The lack of detection of several envelope mutant viruses by some commercial HBsAg assays has been demonstrated. Substitutions involving precore/core region have also been found to prevent HBeAg synthesis.

Update of the human parvovirus B19 biology.

Since its discovery, the human parvovirus B19 (B19V) has been associated with many clinical situations in addition to the prototype clinical manifestations, i.e. erythema infectiosum and erythroblastopenia crisis. The clinical significance of the viral B19V DNA persistence in sera after acute infection remains largely unknown. Such data may constitute a new clinical entity and is discussed in this manuscript. In 2002, despite the genetic diversity among B19V viruses has been reported to be very low, the description of markedly distinct sequences showed a new organization into three genotypes. The most recent common ancestor for B19V genotypes was estimated at early 1800s. B19V replication is enhanced by hypoxia and this might to explain the high viral load detected by quantitative PCR in the sera of infected patients. The minimum infectious dose necessary to transmit B19V infection by the transfusion of labile blood products remains unclear. At the opposite, the US Food and Drug Administration proposed a limit of 10(4)IU/mL of viral DNA in plasma pools used for the production of plasma derivatives. Recently, a new human parvovirus (PARV4) has been discovered. The consequences on blood transfusion of this blood-borne agent and its pathogenicity are still unknown.

A synthetic kisspeptin analog that triggers ovulation and advances puberty.

The neuropeptide kisspeptin and its receptor, KiSS1R, govern the reproductive timeline of mammals by triggering puberty onset and promoting ovulation by stimulating gonadotrophin-releasing hormone (GnRH) secretion. To overcome the drawback of kisspeptin short half-life we designed kisspeptin analogs combining original modifications, triazole peptidomimetic and albumin binding motif, to reduce proteolytic degradation and to slow down renal clearance, respectively. These analogs showed improved in vitro potency and dramatically enhanced pharmacodynamics. When injected intramuscularly into ewes (15 nmol/ewe) primed with a progestogen, the best analog (compound 6, C6) induced synchronized ovulations in both breeding and non-breeding seasons. Ovulations were fertile as demonstrated by the delivery of lambs at term. C6 was also fully active in both female and male mice but was completely inactive in KiSS1R KO mice. Electrophysiological recordings of GnRH neurons from brain slices of GnRH-GFP mice indicated that C6 exerted a direct excitatory action on GnRH neurons. Finally, in prepubertal female mice daily injections (0.3 nmol/mouse) for five days significantly advanced puberty. C6 ability to trigger ovulation and advance puberty demonstrates that kisspeptin analogs may find application in the management of livestock reproduction and opens new possibilities for the treatment of reproductive disorders in humans.

Structural requirements for synthetic immunogens to induce measles virus specific CTL responses.

We have studied the immunogenicity of a synthetic peptide representing a cytotoxic T cell epitope (CTL) from the nucleoprotein of measles virus (MV). For the induction of peptide and MV-specific CTL responses after subcutaneous immunization, covalent linkage of the CTL epitope to a T-helper epitope was required. The presence of two copies of the T-helper epitope at the amino terminus of the CTL epitope (TT-CTL) resulted in the induction of strong CTL responses after administration in saline. In contrast, a chimeric peptide with one copy of the T-helper epitope at the amino terminus of the CTL epitope (T-CTL) was weakly immunogenic when given in saline. Analysis of the structure of the TT-CTL chimeric peptide by CD spectroscopy revealed an alpha-helical conformation, as compared to the random coil conformation favored by the T-CTL chimeric peptide. In addition, the CD spectra of the TT-CTL peptide in the presence of small unilamellar vesicules (SUV) revealed an increased helicity, as compared to the spectra of the T-CTL chimera in the presence of SUV. This suggests that the amphipathic character of the TT-CTL chimeric construct favors its interaction with the cell membrane of antigen presenting cells, therefore, facilitating its cytosolic delivery for class I presentation. These findings highlight the importance of antigen structure for the in vivo induction of CTL responses and may have implications for the design of synthetic peptide vaccines.

Epitopes of the 44-68 human parathyroid hormone fragments: the importance of specific hydrophilic peptide sequences.

Several pentapeptides included in the 44-68 sequence of human parathyroid hormone (hPTH) were synthesized simultaneously on benzhydrylamine and m-nitrobenzhydrylamine resins. The first polymer gave the free peptide and the second the peptidyl-resin complex. An ELISA test carried out with each peptidyl-resin complex showed that all the anti-44-68 hPTH antibodies raised in different animal species are directed against the same hPTH pentapeptidic sequence. This sequence is very hydrophilic and is specific to the hormone. This study demonstrates the importance of specific peptide chains in an epitope.

Oral immunization with a free peptide from cholera toxin: local protection and IgA production.

It is frequently of great benefit for good protection against pathogens to elicit a local immunization. For example the importance of antibacterial as well as antitoxin local secretory IgA, for protection against cholera, has been underlined in several studies. We have already reported that oral administration of the peptide corresponding to the 50-75 sequence of cholera toxin (CT) B subunit elicits serum antibodies neutralizing CT activity. In this study we demonstrate that IgA with specificity to CT are present in intestinal secretions of mice immunized orally with the P50-75 or P30-50 peptides of CT B subunit. In addition local protection is observed in the intestine of P50-75 orally immunized mice. These results point out the potential of synthetic peptides as immunogens at the mucosal level.

[Assessment of dermatological emergencies in a French university hospital]. / Evaluation d'une consultation d'urgences en dermatologie.

INTRODUCTION: The aim of our study was to understand the motivations of outpatients who come to dermatological emergencies in a university hospital. PATIENTS AND METHOD: This 6-week prospective study included outpatients who came to the dermatology emergency unit. This consultation is proposed each morning (from 8 to 9), from Mondays to Fridays. A questionnaire was distributed to outpatients. They answered questions on the functioning of this consultation and their own symptoms. The consulting dermatologist answered questions on the referring physician, the really urgent characteristics of the disease and the diagnosis. RESULTS: Patients were satisfied by the functioning of the consultation. Indeed, 59 p. 100 of outpatients thought that the timetable was convenient and 70 p. 100 that the delay before getting a consultation was rapid. 75 p. 100 felt they needed treatment rapidly. Nonetheless, 45 p. 100 did not think they had a serious disease. More than half of the outpatients were referred by their general practitioner; the others came spontaneously, or were referred by other departments or general emergencies. The most frequent diagnoses were cutaneous infections (27.6 p. 100), eczema (21 p. 100), then benign tumors, psoriasis, physical dermatoses, viral eruptions... DISCUSSION: A consultation for dermatological emergencies appears to reply to patients' demands. Nonetheless, most of these outpatients do not present with real dermatological emergencies. Criteria for real emergencies needs to be further defined and understood by citizens.

Influence of the conformation of a macromolecule on the generation of T-cell proliferative response. A study with model polypeptides.

To study the influence of the conformation of polypeptidic macromolecules on the generation of T-cell epitopes, sequential polypeptides with an octamer repeat unit were designed and synthesized. They adopt mainly unordered and alpha-helical conformations. Among these polypeptides, those containing proline are fully or partly unordered, and are more effective at inducing T-cell proliferation than a proline-free very stable alpha-helical polypeptide. This extremely stable alpha-helical conformation, probably stabilized by aggregation, would enhance its stability against proteolytic processing.

Efficient binding to the MHC class I K(d) molecule of synthetic peptides in which the anchoring position 2 does not fit the consensus motif.

Peptides eluted from the MHC class I K(d) molecule are generally nonamers that display a strong preference for Tyr in position 2 and Ile or Leu in position 9. We investigated the binding ability of several synthetic peptides which did not fit this consensus motif. In our peptides, Tyr(2) was substituted by other amino acids, i.e. LeU, Ile or Met. These peptides were variants of the 252-260 K(d)-restricted peptide SYIPSAEKI derived from the Plasmodium berghei circumsporozoite protein. They bound to purified K(d) molecules in vitro with intermediate affinity. One of them was tested for in vivo stimulation of T cells and induced a cytotoxic response. These results demonstrate the importance of binding motif refinement to discover new binding characteristics and new ligands such as low-affinity peptides.

In-source fragmentation of peptide aldehydes and acetals: influence of peptide length and charge state.

The use of in-source collision-induced dissociation (CID) was evaluated to generate structural information on peptide aldehydes, which represent an important class of compounds as inhibitors for serine and cysteine proteases and as key intermediates for protein engineering. By studying five peptide aldehydes of different lengths, and their peptide acetal counterparts, mass to charge (m/z) dependency of in-source fragmentation was established for peptides that differ only by their C-terminal functionalization. In-source fragmentation of peptide aldehydes and acetals leads to the same final ion, probably via a similar mechanism. Moreover, the gas-phase information obtained here reflects the equilibrium occurring in solution between the peptide aldehyde and its hydrated form, which was retained during the ionization process. The equilibrium constant was determined to be close to unity. Disturbance of this equilibrium should enable the stability of covalent hydration of a given series of aldehydes to be compared.

[Indications of vasopressin in the management of septic shock]. / Place de la vasopressine chez les patients en choc septique.

OBJECTIVE: Vasopressin (antidiuretic hormone) is emerging as a potentially major advancement in the treatment of septic shock. Vasopressin is both a vasopressor and an antidiuretic hormone. It also has haemostatic, gastrointestinal, and thermoregulatory effects. This article reviews the physiology of vasopressin and all the relevant clinical literature on its use in the treatment of septic shock. DATA SOURCES AND EXTRACTION: Extraction from Pubmed database of French and English articles on the physiology and clinical use of vasopressin. The following key words were selected: vasodilatory shock, vasopressin, septic shock, catecholamines, norepinephrine, renal function, diuresis, mesenteric haemodynamic. The collected articles were reviewed and selected according to their quality and originality. DATA SYNTHESIS: Vasopressin mediates vasoconstriction via V1-receptor activation on vascular smooth muscle. Septic shock causes first a transient early increase in blood vasopressin concentrations that decreases later to very low concentrations compared to other causes of hypotension. Vasopressin infusion of 0.01-0.04 U min(-1) in septic shock patients increases plasma vasopressin concentrations. This increase is associated with a lesser need for other vasopressors. Vasopressin has been shown to produce greater blood flow diversion from non-vital to vital organ beds than does adrenaline. A large randomized clinical trial should be performed to assess its place as a therapeutic agent of septic shock patient.