A new mass spectrometry-based method for the quantification of histones in plasma from septic shock patients

The aim of this study was to develop a novel method to detect circulating histones H3 and H2B in plasma based on multiple reaction monitoring targeted mass spectrometry and a multiple reaction monitoring approach (MRM-MS) for its clinical application in critical bacteriaemic septic shock patients. Plasma samples from 17 septic shock patients with confirmed bacteraemia and 10 healthy controls were analysed by an MRM-MS method, which specifically detects presence of histones H3 and H2B. By an internal standard, it was possible to quantify the concentration of circulating histones in plasma, which were significantly higher in patients, and thus confirmed their potential as biomarkers for diagnosing septic shock. After comparing surviving patients and non-survivors, a correlation was found between higher levels of circulating histones and unfavourable outcome. Indeed, histone H3 proved a more efficient and sensitive biomarker for septic shock prognosis. In conclusion, these findings suggest the accuracy of the MRM-MS technique and stable isotope labelled peptides to detect and quantify circulating plasma histones H2B and H3. This method may be used for early septic shock diagnoses and for the prognosis of fatal outcomes.

TRPC1 and metabotropic glutamate receptor expression in rat auditory midbrain neurons

Canonical transient receptor potential (TRPC) channels are plasma membrane cation channels included in the TRP superfamily. TRPC1 is expressed widely in the central nervous system and is linked to group I metabotropic glutamate receptors (mGluRs). In the auditory brainstem, TRPC1 expression has never been described, although group I mGluRs are present. In the central nucleus of the inferior colliculus (CIC), activation of group I mGluRs induces an extracellular Ca(2+) influx after store depletion. Therefore, this study examines whether TRPC1 is expressed in this region to establish a correlation with mGluRs. By quantitative reverse transcription-polymerase chain reaction and Western blotting, this study assesses the presence of TRPC1 along with both group I mGluR subtypes mGluR1 and mGluR5 in the rat inferior colliculus (IC). All these molecules present a robust expression in the IC. By confocal double immunofluorescence, this study also demonstrates that TRPC1 colocalizes with parvalbumin, a CIC neuronal marker, in many cells. Conversely, TRPC1 was lacking in glial fibrillary acidic protein-positive glial cells. All the glutamate acid decarboxylase 67 (GAD67)-immunoreactive neurons and many GAD67-negative neurons were positive to TRPC1, which indicates the presence of TRPC1 in γ-aminobutyric acid (GABA)-ergic and non-GABAeregic neurons. With regard to subcellular distribution, TRPC1 was absent in synaptophysin-immunoreactive axonic terminals but colocalized with postsynaptic marker microtubule-associated protein 2 in cell bodies and dendrites. TRPC1 totally overlapped group I mGluRs, which supports the involvement of TRPC1 in the mGluR pathway and, likely, in auditory signal processing at the midbrain level. .

Proteomic analysis of in vitro newly excysted juveniles from Fasciola hepatica

Fasciolosis is a world-wide distributed zoonotic disease affecting several herbivores, and represents an important factor of economic loss in animal meat producing industries. In addition, specific risk factors and geographic areas for Fasciola hepatica human infection have been heavily reported recently. Several aspects related with this disease, e.g., drug resistance and prevention through vaccination, have yet to be solved. After ingestion, the infective stage for the vertebrate host-metacercariae - hatch in duodenum and the newly excysted juveniles (NEJ) penetrate the intestinal wall. The identification of proteins expressed by NEJ and specifically those found in the host-parasite interface could help understanding the first steps of animal and human infection by F. hepatica. Here we use a proteomic approach to identify a set of proteins enriched at the host-parasite interface from in vitro NEJ by applying liquid chromatography and tandem mass spectrometry (LC-MS/MS) analysis. Using this approach, we identified numerous proteins related with several biological processes of the parasite. In addition, we characterize one of the identified molecules, the 14-3-3z protein, and demonstrate its association with the outer structures of NEJ and its presence in both somatic and secretory components from the parasite. The NEJ proteins described here, together with those previously described by others, could provide new insights into the biology of the parasite and its relationship with the vertebrate host at the beginning of the infection.

Screening of antifeedant activity in brain extracts led to the identification of sulfakinin as a satiety promoter in the German cockroach. Are arthropod sulfakinins homologous to vertebrate gastrins-cholecystokinins?

The feeding cycle of the adult female cockroach Blattella germanica parallels vitellogenesis. The study of the mechanisms that regulate this cycle led us to look for food-intake inhibitors in brain extracts. The antifeedant activity of brain extracts was tested in vivo by injecting the extract and measuring the carotenoids contained in the gut from carrot ingested after the treatment. By HPLC fractionation and tracking the biological activity with the carrot test, we isolated the sulfakinin EQFDDY(SO3H) GHMRFamide (Pea-SK). A synthetic version of the peptide inhibited food intake when injected at doses of 1 microg (50% inhibition) and 10 microg (60% inhibition). The sulfate group was required for food-intake inhibition. These biological and structural features are similar to those of the gastrin-cholecystokinin (gastrin-CCK) family of vertebrate peptides. However, heterologous feeding assays (human CCK-8 tested on B. germanica, and Pea-SK tested on the goldfish Carassius auratus) were negative. In spite of this, alignment and cluster analysis of these and other structurally similar peptide families suggest that sulfakinins and gastrin-CCKs are homologous, and that mechanisms of feeding regulation involving these regulatory peptides may have been conserved during evolution between insects and vertebrates.

Identification of T-cell epitopes in nonstructural proteins of foot-and-mouth disease virus

Porcine T-cell recognition of foot-and-mouth disease virus (FMDV) nonstructural proteins (NSP) was tested using in vitro lymphoproliferative responses. Lymphocytes were obtained from outbred pigs experimentally infected with FMDV. Of the different NSP, polypeptides 3A, 3B, and 3C gave the highest stimulations in the in vitro assays. The use of overlapping synthetic peptides allowed the identification of amino acid regions within these proteins that were efficiently recognized by the lymphocytes. The sequences of some of these antigenic peptides were highly conserved among different FMDV serotypes. They elicited major histocompatibility complex-restricted responses with lymphocytes from pigs infected with either a type C virus or reinfected with a heterologous FMDV. A tandem peptide containing the T-cell peptide 3A[21-35] and the B-cell antigenic site VP1[137-156] also efficiently stimulated lymphocytes from infected animals in vitro. Furthermore, this tandem peptide elicited significant levels of serotype-specific antiviral activity, a result consistent with the induction of anti-FMDV antibodies. Thus, inclusion in the peptide formulation of a T-cell epitope derived from the NSP 3A possessing the capacity to induce T helper activity can allow cooperative induction of anti-FMDV antibodies by B cells.

Native-like cyclic peptide models of a viral antigenic site: finding a balance between rigidity and flexibility

Antigenic site A of foot-and-mouth disease virus (serotype C) has been reproduced by means of cyclic versions of peptide A15, YTASARGDLAHLTTT, corresponding to residues 136-150 of envelope protein VP1. A structural basis for the design of the cyclic peptides is provided by crystallographic data from complexes between the Fab fragments of anti-site A monoclonal antibodies and A15, in which the bound peptide is folded into a quasi-cyclic pattern. Head-to-tail cyclizations of A15 do not provide peptides of superior antigenicity. Internal disulfide cyclization, however, leads to analogs which are recognized as one to two orders of magnitude better than linear A15 in both ELISA and biosensor experiments. CD and NMR studies show that the best antigen, CTASARGDLAHLTT-Ahx-C (disulfide), is very insensitive to environment-induced conformational change, suggesting that cyclization helps to stabilize a bioactive-like structure.

Synthesis of cyclic Herpes simplex virus peptides containing 281-284 epitope of glycoprotein D-1 in endo- or exo-position

We have prepared two types of cyclopeptides containing the 281DPVG284 sequence from the 276-284 region of glycoprotein gD-1 of the Herpes simplex virus (HSV). The syntheses were performed by solid phase methodology using MBHA or BHA resin and orthogonal protection schemes. Head-to-side-chain cyclization included the N-terminal part of the epitope, while side-chain-to-side-chain lactam bridge formation resulted in a peptide containing a C-terminal cycle. Peptides elongated by Cys at the N-terminal of the sequence were also prepared. Boc chemistry using Fmoc and OFm orthogonal protection was applied for on-resin cyclization. Based on the orthogonality of Bzl and cHex esters under a 1 M TMSOTf-thioanisole/TFA cleavage condition, a new approach for the cyclization on BHA-resin has also been developed. Preliminary studies on solution conformation of the cyclic peptides by CD spectroscopy indicated the importance of the location and the size of the cycle within the epitope sequence.

A comparative study of cyclization strategies applied to the synthesis of head-to-tail cyclic analogs of a viral epitope

A family of head-to-tail cyclic peptide models of the antigenic site A (G-H loop of viral protein 1) of foot-and-mouth disease virus has been designed on the basis of the three-dimensional structure adopted by the linear peptide YTASARGDLAHLTTT upon binding to neutralizing monoclonal antibodies. Three different methods of cyclization have been examined to access the peptides. Solution cyclization of a minimally protected linear precursor provided the expected products but required several purification steps that lowered the yields to approximately 10%. The two other approaches relied on side-chain anchoring of the peptide through the Asp residue and cyclization on the solid phase. A synthetic scheme combining Fmoc, tBu and OAI protections was practicable but inefficient when scaled-up. The combination of Boc, Bzl and OFm protections was more promising, but suffered from high epimerization during the initial esterification of Boc-Asp-OFm to benzyl alcohol-type resins. This problem was solved by performing the esterification via the cesium salt of Boc-Asp-OFm. With this improvement, the Boc/Bzl/OFm has become the method of choice for the preparation of cyclic head-to-tail peptides in satisfactory yields and with minimal purification.

A similar pattern of interaction for different antibodies with a major antigenic site of foot-and-mouth disease virus: implications for intratypic antigenic variation

The three-dimensional structures of the Fab fragment of a neutralizing antibody raised against a foot-and-mouth disease virus (FMDV) of serotype C1, alone and complexed to an antigenic peptide representing the major antigenic site A (G-H loop of VP1), have been determined. As previously seen in a complex of the same antigen with another antibody which recognizes a different epitope within antigenic site A, the receptor recognition motif Arg-Gly-Asp and some residues from an adjacent helix participate directly in the interaction with the complementarity-determining regions of the antibody. Remarkably, the structures of the two antibodies become more similar upon binding the peptide, and both undergo considerable induced fit to accommodate the peptide with a similar array of interactions. Furthermore, the pattern of reactivities of five additional antibodies with versions of the antigenic peptide bearing amino acid replacements suggests a similar pattern of interaction of antibodies raised against widely different antigens of serotype C. The results reinforce the occurrence of a defined antigenic structure at this mobile, exposed antigenic site and imply that intratypic antigenic variation of FMDV of serotype C is due to subtle structural differences that affect antibody recognition while preserving a functional structure for the receptor binding site.

Cyclic peptides as conformationally restricted models of viral antigens: application to foot-and-mouth disease virus

Conformationally restricted cyclic peptide mimics of the antigenic site A of foot-and-mouth disease virus serotype C-S8c1 have been designed, first by comparison to the three-dimensional structure of the O1BFS serotype, later more accurately on the basis of X-ray diffraction data from a complex between a linear peptide reproducing site A and an FMDV-derived monoclonal antibody Fab fragment. A variety of cyclization strategies have been attempted, both in solution and in the solid phase, involving disulfide, side chain lactam and head-to-tail arrangements. Preliminary immunological results have shown one of the cyclic disulfide mimics to be a better immunogen than its linear counterpart.

A large-scale evaluation of peptide vaccines against foot-and-mouth disease: lack of solid protection in cattle and isolation of escape mutants

A large-scale vaccination experiment involving a total of 138 cattle was carried out to evaluate the potential of synthetic peptides as vaccines against foot-and-mouth disease. Four types of peptides representing sequences of foot-and-mouth disease virus (FMDV) C3 Argentina 85 were tested: A, which includes the G-H loop of capsid protein VP1 (site A); AT, in which a T-cell epitope has been added to site A; AC, composed of site A and the carboxy-terminal region of VP1 (site C); and ACT, in which the three previous capsid motifs are colinearly represented. Induction of neutralizing antibodies, lymphoproliferation in response to viral antigens, and protection against challenge with homologous infectious virus were examined. None of the tested peptides, at several doses and vaccination schedules, afforded protection above 40%. Protection showed limited correlation with serum neutralization activity and lymphoproliferation in response to whole virus. In 12 of 29 lesions from vaccinated cattle that were challenged with homologous virus, mutant FMDVs with amino acid substitutions at antigenic site A were identified. This finding suggests the rapid generation and selection of FMDV antigenic variants in vivo. In contrast with previous studies, this large-scale vaccination experiment with an important FMDV host reveals considerable difficulties for vaccines based on synthetic peptides to achieve the required levels of efficacy. Possible modifications of the vaccine formulations to increase protective activity are discussed.

Effect of pH and buffer system on the in-vitro activity of five antifungals against yeasts

We have compared the effect of various media on the in-vitro activity of amphotericin B, flucytosine, fluconazole, itraconazole and ketoconazole against 93 clinical yeast isolates by a micro-broth dilution technique. The media used were: RPMI 1640 with 2% glucose, buffered with 0.165 M MOPS at pH 7.0; the same medium, but buffered at pH 7.4; and the same medium, but buffered at pH 7.4 with 0.15% sodium bicarbonate. The three media gave similar results with azole antifungals and flucytosine, but the medium buffered at pH 7.0 failed to detect different populations of yeasts with respect to amphotericin B susceptibility. In the case of the media buffered at pH 7.4, Candida krusei was significantly less susceptible to amphotericin B than Candida albicans or Torulopsis glabrata. We could not evaluate the results obtained with Candida parapsilosis and Cryptococcus neoformans since these species did not grow adequately in all three media.

Systematic replacement of amino acid residues within an Arg-Gly-Asp-containing loop of foot-and-mouth disease virus and effect on cell recognition

The conserved Arg-Gly-Asp (RGD) motif found in a hypervariable, mobile antigenic loop of foot-and-mouth disease virus (FMDV) is critically involved in virus attachment to cells by binding to an integrin, probably related to alphavbeta3. Here we describe (i) the synthesis of 241 15-mer peptides, which represent this loop of FMDV (isolate C-S8c1) and single variants in which each amino acid residue was replaced by 16 others and (ii) the inhibitory activity of these peptides on the ability of FMDV C-S8c1 to recognize and infect susceptible cells. This approach has allowed a first detailed evaluation of the specificity of each residue within a RGD-containing protein loop on cell recognition. The results indicate that, in addition to the exquisitely specific RGD triplet, two highly conserved Leu residues located at positions +1 and +4 downstream of the RGD and, to a lesser extent, the residue at position +2 are the only critical and specific determinants within the loop in promoting cell recognition of a viral ligand. The results support the proposal that, in spite of their involvement in antibody recognition, RGD and other FMDV loop residues are remarkably conserved because of their essential role in cell recognition.

Antibody and host cell recognition of foot-and-mouth disease virus (serotype C) cleaved at the Arg-Gly-Asp (RGD) motif: a structural interpretation

Foot-and-mouth disease virus (FMDV) of serotype C (isolate C-S8c1) was cleaved in situ by trypsin at the Arg-Gly-Asp (RGD) motif, which is involved both in attachment of FMDV to cells and in recognition of a major antigenic site (site A) by antibodies. Though 99.4% of the RGD moieties were cleaved, the virus remained infectious. A synthetic peptide which represented the sequence of the VP1 G-H loop of C-S8c1, including the RGD motif, greatly inhibited FMDV attachment to cells. The same peptide inhibited, very effectively and to the same extent (50% inhibition at about 1 microM), the infectivity of both intact and trypsin-treated virus. Replacement of Asp with Glu at the RGD motif abolished the inhibitory effects of the peptide. Thus, the RGD motif is involved in the infectivity of both intact and RGD-cleaved serotype C FMDV. Trypsin treatment did not affect the reactivity of the virus with some monoclonal antibodies (MAbs) directed to site A whose epitopes involve mainly residues contiguous to the cleaved bond, but diminished the reactivity with site A MAbs whose epitopes include the RGD sequence and flanking residues. However, high concentrations of any site A MAb tested neutralized close to 100% of the infectious trypsin-treated virus. We propose that, in spite of covalent cleavage, the high number of intramolecular non-covalent interactions observed within the G-H loop of FMDV C-S8c1 (complexed to antibody) may hold the RGD in a nearly correct conformation and allow--albeit with reduced affinity--antibody and cell receptor recognition of RGD-cleaved FMDV.

Emerging foot-and-mouth disease virus variants with antigenically critical amino acid substitutions predicted by model studies using reference viruses

One of the major obstacles to the design of effective antiviral vaccines is the frequent generation of antigenic viral variants in the field. The types of variants that will become dominant during disease outbreaks is often unpredictable. However, here we report the genetic and antigenic characterization of emerging foot-and-mouth disease virus (FMDV) variants with antigenically critical amino acid substitutions predicted by model studies using reference viruses and monoclonal antibodies. The new variants belong to serotype C and have caused a number of recent disease outbreaks in Argentina. The variants harbor antigenically drastic amino acid substitutions in each of the antigenic sites identified in FMDV. In particular, a substitution found at a major antigenic site (site A, the G-H loop of VP1) had been repeatedly selected in viruses resistant to neutralization by monoclonal and polyclonal antibodies. The association of critical amino acid replacements at predicted positions with new FMD outbreaks has a number of implications for FMD epidemiology and for the design of vaccines intended to control diseases caused by highly variable RNA viruses.

[Essential thrombocythemia: a myeloproliferative state on the rise. Clinico-biological study and course of 44 cases]

Forty-four cases of essential thrombocytosis (ET) were diagnosed in the last 20 years, 19 males and 24 females (M/F: 0.76), aged between 3 and 86 years (median, 62 years), and 9 of them being under 40 years of age. The M/F ratio for patients under 60 years was 0.5, whereas it was 1.09 for patients over 60. The clinical forms at onset were: asymptomatic, 36.5%; as a bleeding disorder (BD), 20.4%; as thrombotic disease (TD) 22.7%; BD/TD, 13.6%, and others, 6.8%. The most important biological features included platelet count over 1.000 x 10(9)/L (59.1%), abnormal platelet aggregation, chiefly with ADR (56.5), mild reticulin myelofibrosis (55%), abnormal karyotype (2.6%), moderately high LDH levels (56.8%) and pseudo-hyperkalaemia (40%). The initial therapeutic approach was: observation (12 cases), antiaggregating agents (6 cases), and chemotherapy (BSF, HU, etc.) in the remainders. One patient evolved quickly into acute myelogenous leukaemia and two others suffered a late transformation into polycythaemia vera (PV) and myeloid metaplasia, respectively. The median survival was over 11 years, this being longer in patients under 60 years of age, in those with platelet count at diagnosis between 600 and 1000 x 10(9)/L and in those without initial symptoms of thrombosis. The advent of electronic blood-cell counters has made ET no longer a rare chronic myeloproliferative disease, its incidence coming now closer to that of PV; thus, in the last four quinquennial periods the incidence of ET/PV has evolved as following: 1/19, 4/16, 13/18 and 26/29.