Verification of fetal brain responses by coregistration of fetal ultrasound and fetal magnetoencephalography data

Fetal magnetoencephalography (fMEG) is used to study neurological functions of the developing fetus by measuring magnetic signals generated by electrical sources within the fetal brain. For this aim either auditory or visual stimuli are presented and evoked brain activity or spontaneous activity is measured at the sensor level. However a limiting factor of this approach is the low signal to noise ratio (SNR) of recorded signals. To overcome this limitation, advanced signal processing techniques such as spatial filters (e.g., beamformer) can be used to increase SNR. One crucial aspect of this technique is the forward model and, in general, a simple spherical head model is used. This head model is an integral part of a model search approach to analyze the data due to the lack of exact knowledge about the location of the fetal head. In the present report we overcome this limitation by a coregistration of volumetric ultrasound images with fMEG data. In a first step we validated the ultrasound to fMEG coregistration with a phantom and were able to show that the coregistration error is below 2 cm. In the second step we compared the results gained by the model search approach to the exact location of the fetal head determined on pregnant mothers by ultrasound. The results of this study clearly show that the results of the model search approach are in accordance with the location of the fetal head.

Influenza-like illness sentinel surveillance in Peru

Background

Acute respiratory illnesses and influenza-like illnesses (ILI) are a significant source of morbidity and mortality worldwide. Despite the public health importance, little is known about the etiology of these acute respiratory illnesses in many regions of South America. In 2006, the Peruvian Ministry of Health (MoH) and the US Naval Medical Research Center Detachment (NMRCD) initiated a collaboration to characterize the viral agents associated with ILI and to describe the clinical and epidemiological presentation of the affected population.

Methodology/Principal Findings

Patients with ILI (fever ≥38°C and cough or sore throat) were evaluated in clinics and hospitals in 13 Peruvian cities representative of the four main regions of the country. Nasal and oropharyngeal swabs, as well as epidemiological and demographic data, were collected from each patient. During the two years of this study (June 2006 through May 2008), a total of 6,835 patients, with a median age of 13 years, were recruited from 31 clinics and hospitals; 6,308 were enrolled by regular passive surveillance and 527 were enrolled as part of outbreak investigations. At least one respiratory virus was isolated from the specimens of 2,688 (42.6%) patients, with etiologies varying by age and geographical region. Overall the most common viral agents isolated were influenza A virus (25.1%), influenza B virus (9.7%), parainfluenza viruses 1, 2, and 3, (HPIV-1,-2,-3; 3.2%), herpes simplex virus (HSV; 2.6%), and adenoviruses (1.8%). Genetic analyses of influenza virus isolates demonstrated that three lineages of influenza A H1N1, one lineage of influenza A H3N2, and two lineages of influenza B were circulating in Peru during the course of this study.

Conclusions

To our knowledge this is the most comprehensive study to date of the etiologic agents associated with ILI in Peru. These results demonstrate that a wide range of respiratory pathogens are circulating in Peru and this fact needs to be considered by clinicians when treating patients reporting with ILI. Furthermore, these data have implications for influenza vaccine design and implementation in South America.

Four disulfide-bridged scorpion beta neurotoxin CssII: Heterologous expression and proper folding in vitro

The gene of the four disulfide-bridged Centruroides suffusus suffusus toxin II was cloned into the expression vector pQE30 containing a 6His-tag and a FXa proteolytic cleavage region. This recombinant vector was transfected into Escherichia coli BL21 cells and expressed under induction with isopropyl thiogalactoside (IPTG). The level of expression was 24.6 mg/l of culture medium, and the His tagged recombinant toxin (HisrCssII) was found exclusively in inclusion bodies. After solubilization the HisrCssII peptide was purified by affinity and hydrophobic interaction chromatography. The reverse-phase HPLC profile of the HisrCssII product obtained from the affinity chromatography step showed several peptide fractions having the same molecular mass of 9392.6 Da, indicating that HisrCssII was oxidized forming several distinct disulfide bridge arrangements. The multiple forms of HisrCssII after reduction eluted from the column as a single protein component of 9400.6 Da. Similarly, an in vitro folding of the reduced HisrCssII generated a single oxidized component of HisrCssII, which was cleaved by the proteolytic enzyme FXa to the recombinant CssII (rCssII). The molecular mass of rCssII was 7538.6 Da as expected. Since native CssII (nCssII) is amidated at the C-terminal residue whereas the rCssII is heterologously expressed in the format of free carboxyl end, there is a difference of 1 Da, when comparing both peptides (native versus heterologously expressed). Nevertheless, they show similar toxicity when injected intracranially into mice, and both nCssII and rCssII show the typical electrophysiological properties of beta-toxins in Na(v)1.6 channels, which is for the first time demonstrated here. Binding and displacement experiments conducted with radiolabelled CssII confirms the electrophysiological results. Several problems associated with the heterologously expressed toxins containing four disulfide bridges are discussed.

Novel alpha-conotoxins from Conus spurius and the alpha-conotoxin EI share high-affinity potentiation and low-affinity inhibition of nicotinic acetylcholine receptors

alpha-Conotoxins from marine snails are known to be selective and potent competitive antagonists of nicotinic acetylcholine receptors. Here we describe the purification, structural features and activity of two novel toxins, SrIA and SrIB, isolated from Conus spurius collected in the Yucatan Channel, Mexico. As determined by direct amino acid and cDNA nucleotide sequencing, the toxins are peptides containing 18 amino acid residues with the typical 4/7-type framework but with completely novel sequences. Therefore, their actions (and that of a synthetic analog, [gamma15E]SrIB) were compared to those exerted by the alpha4/7-conotoxin EI from Conus ermineus, used as a control. Their target specificity was evaluated by the patch-clamp technique in mammalian cells expressing alpha(1)beta(1)gammadelta, alpha(4)beta(2) and alpha(3)beta(4) nicotinic acetylcholine receptors. At high concentrations (10 microm), the peptides SrIA, SrIB and [gamma15E]SrIB showed weak blocking effects only on alpha(4)beta(2) and alpha(1)beta(1)gammadelta subtypes, but EI also strongly blocked alpha(3)beta(4) receptors. In contrast to this blocking effect, the new peptides and EI showed a remarkable potentiation of alpha(1)beta(1)gammadelta and alpha(4)beta(2) nicotinic acetylcholine receptors if briefly (2-15 s) applied at concentrations several orders of magnitude lower (EC(50), 1.78 and 0.37 nm, respectively). These results suggest not only that the novel alpha-conotoxins and EI can operate as nicotinic acetylcholine receptor inhibitors, but also that they bind both alpha(1)beta(1)gammadelta and alpha(4)beta(2) nicotinic acetylcholine receptors with very high affinity and increase their intrinsic cholinergic response. Their unique properties make them excellent tools for studying the toxin-receptor interaction, as well as models with which to design highly specific therapeutic drugs.

The CDR1 of the human λVI light chains adopts a new canonical structure

We performed a comparative analysis of the conformation of the CDR1 of the human lambdaVI variable domains JTO and WIL and the equivalent loop of the lambdaI light chains RHE and KOL, which are representative of the type I canonical structure for lambda light chains. On the basis of the differences found in the main chain conformation, as well as the identity of the residues at key positions, we showed that the L1 of some lambdaVI light chains adopts a conformation that represents a new type of canonical structure. The conformation of the L1 of those lambdaVI light chains, is primarily determined by the presence of an Arg residue at position 25. The analysis of the lambdaVI light chain sequences so far reported, showed that near 25% of those proteins have Gly at position 25 instead of Arg, which represents an allotypic variant of the lambdaVI variable locus. The presence of Gly at position 25 in the L1 of lambdaVI light chains would imply a different conformation for this loop. Additionally, the position 68 in lambdaVI light chains, which is at the top of the FR3 loop, showed such spatial orientation and variability that suggested its participation in the conformation of the antigen recognition surface in this subgroup of lambda chains.

A Novel Conotoxin from Conus delessertii with Posttranslationally Modified Lysine Residues

A major peptide, de13a from the crude venom of Conus delessertii collected in the Yucatan Channel, Mexico, was purified. The peptide had a high content of posttranslationally modified amino acids, including 6-bromotryptophan and a nonstandard amino acid that proved to be 5-hydroxylysine. This is the first report of 5-hydroxylysine residues in conotoxins. The sequence analysis, together with cDNA cloning and a mass determination (monoisotopic mass of 3486.76 Da), established that the mature toxin has the sequence DCOTSCOTTCANGWECCKGYOCVNKACSGCTH, where O is 4-hydroxyproline, W 6-bromotryptophan, and K 5-hydroxylysine, the asterisk represents the amidated C-terminus, and the calculated monoisotopic mass is 3487.09 Da. The eight Cys residues are arranged in a pattern (C-C-C-CC-C-C-C) not described previously in conotoxins. This arrangement, for which we propose the designation of framework #13 or XIII, differs from the ones (C-C-CC-CC-C-C and C-C-C-C-CC-C-C) present in other conotoxins which also contain eight Cys residues. This peptide thus defines a novel class of conotoxins, with a new posttranslational modification not previously found in other Conus peptide families.

Effect of manipulation of iron storage, transport, or availability on myelin composition and brain iron content in three different animal models

Several observations suggest that iron is an essential factor in myelination and oligodendrocyte biology. However, the specific role of iron in these processes remains to be elucidated. This role could be as an essential cofactor in metabolic processes or as a transcriptional or translational regulator. In this study, we used animals models each with a unique defect in iron availability, storage, or transfer to test the hypothesis that disruptions in these mechanisms affect myelinogenesis and myelin composition. Disruption of iron availability either by limiting dietary iron or by altering iron storage capacity resulted in a decrease in myelin proteins and lipids but not the iron content of myelin. Among the integral myelin proteins, proteolipid protein was most consistently affected, suggesting that limiting iron to oligodendrocytes results not only in hypomyelination but also in a decrease in myelin compaction. Mice deficient in transferrin must receive transferrin injections beginning at birth to remain viable, and these mice had increases in all of the myelin components and in the iron content of the myelin. This finding indicates that the loss of endogenous iron mobility in oligodendrocytes could be overcome by application of exogenous transferrin. Overall, the results of this study demonstrate how myelin composition can be affected by loss of iron homeostasis and reveal specific chronic changes in myelin composition that may affect behavior and attempts to rescue myelin deficits.

Human single chain Fv antibodies and a complementarity determining region-derived peptide binding to amyloid-beta 1–42

A library of phage-displayed human single-chain Fv (scFv) antibodies was selected against the human amyloid-beta peptide (Abeta42). Two new anti-Abeta42 phage-displayed scFvs antibodies were obtained, and the sequences of their V(H) and Vkappa genes were analyzed. A synthetic peptide based on the sequence of Ig heavy chain (V(H)) complementarity-determining region (HCDR3) of the clone with the highest recognition signal was generated and determined to bind to Abeta42 in ELISA. Furthermore, we showed for the first time that an HCDR3-based peptide had neuroprotective potential against Abeta42 neurotoxicity in rat cultured hippocampal neurons. Our results suggest that not only scFvs recognizing Abeta42 but also synthetic peptides based on the V(H) CDR3 sequences of these antibodies may be novel potential candidates for small molecule-based Alzheimer's disease (AD) therapy.

Anti-nucleosome antibodies in patients with systemic lupus erythematosus of recent onset. Potential utility as a diagnostic tool and disease activity marker

OBJECTIVE

To compare the utility of anti-chromatin antibodies for the diagnosis of systemic lupus erythematosus (SLE) and as markers of disease activity.

METHODS

We included 73 consecutive patients (62 female) with SLE (four or more ACR criteria) of recent onset (<1 yr since diagnosis). As control groups we included 130 healthy blood donors and 261 patients with 11 systemic autoimmune diseases (SAD). Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). A venous blood sample was drawn to measure three anti-chromatin antibodies [anti-nucleosome (anti-NCS), anti-double-stranded DNA (anti-dsDNA) and anti-histones (anti-HST)] by enzyme-linked immunosorbent assay.

RESULTS

The prevalence of anti-chromatin antibodies in SLE patients and healthy controls was 100 and 3% respectively for anti-NCS, 63 and 5% for anti-dsDNA, and 15 and 3% for anti-HST. Anti-NCS had a sensitivity of 100% and specificity of 97% for SLE diagnosis. When SLE and SAD patients were compared [excluding mixed connective tissue disease (MCTD)], the sensitivity of anti-NCS, anti-dsDNA and anti-HST antibodies for SLE diagnosis was 93, 71 and 40% respectively and the specificity was 97, 98 and 98%. Anti-chromatin antibodies were not useful in differentiating between SLE and MCTD patients. Anti-NCS antibodies showed the highest correlation with disease activity (r = 0.45, P < 0.0001), especially in patients negative for anti-dsDNA antibodies (r = 0.58, P = 0.001). Anti-NCS antibodies also showed strong association with renal damage (odds ratio 4.1, 95% confidence interval 1.2-13.6, P = 0.01).

CONCLUSION

Anti-NCS antibodies could be a useful tool in the diagnosis and assessment of disease activity in SLE patients, especially in patients who are negative for anti-dsDNA antibodies.

[Orthotopic liver transplant in rats. Surgical technique, complications and treatment]

The orthotopic rat liver transplant model is a widely used technique in transplantation research. It has many advantages over other animal transplant models because of its availability and low cost. However, it must be emphasized that success with the rat model requires thorough training. The aim of this paper is to describe the microsurgical technique involved in 60 rat liver transplants and to discuss the complications and their treatments. Forty-nine liver transplants were performed at the Experimental Laboratory of the University Hospital, Ontario, Canada (ELUH) and 11 were performed at the Laboratorio de Trasplante de Organos de la Facultad de Ciencias Médicas de La Plata, Buenos Aires. Argentina (LTO). Among the transplants performed at the ELUH, the observed complications were haemorrhage (n = 4), pneumothorax (n = 1), anastomotic failure (n = 15), bile leak (n = 3), and bile duct necrosis (n = 9). The remaining 17 rats at the ELUH were healthy at day 7 after surgery. Animal survival immediately postop, at 24 hours postop and at 7 days postop was achieved with the 9th, 20th and 21st transplants respectively. At the LTO, 3 rats died as a result of anaesthetic complications. Seven-day animal survival was achieved with the 11th transplant. We beleive that the description of the orthotopic rat liver transplantation technique, as well as the discussion regarding complications and their management, can be useful for researchers interested in performing liver transplantation in rats.