Chromosomal rearrangement in the 22q11.2 region: a critical locus for sociability and attentional skills

Rearrangements of 22q11.2 region, most often deletions and duplications, are responsible for multiple congenital disorders. These rearrangements are involved in syndromes that share some phenotypic similarities. To date, 22q11.2 triplication remains very rare, with few cases described in the literature. Here, we report for the first time the clinical, neurocognitive, social cognition and psychiatric properties of a 6-year-old child with 22q11.2 triplication, in comparison with a patient with 22q11.2 duplication and 16 cases of patients with 22q11.2 deletion. Chromosomal region 22q11.2 seems to be a critical locus for sociability and attentional skills and rearrangements could be interpreted as a predisposing factor for the development of psychotic symptoms (22q11.2 deletion), a protective factor (22q11.2 duplication) or a tendency factor for hypersociability (22q11.2 triplication).

A Novel Leptin Receptor LEPR Variant in a Toddler With Early-Onset Fatal Obesity

Monogenic obesity generally results in severe early-onset obesity associated with abnormal feeding behavior and endocrine disorders. We report here an extremely severe case of early-onset obesity associated with hyperphagia in an 11-month-old boy without other signs of a syndromic obesity. He developed severe obstructive sleep apnea, dyslipidemia, hepatic steatosis with cytolysis, and acanthosis nigricans with insulin resistance in the first months of life. Laboratory investigations showed an elevated serum leptin level (80.03 ng/mL, normal range 2.45-6.55 ng/mL). Next-generation sequencing of obesity genes panel identified a novel homozygous intronic variant in leptin receptor gene (LEPR), c.703 + 5G>A, predicting affected splicing that resulted in a frameshift, premature stop, and truncation of the protein beyond the cytokine receptor homology domain 1. The child died at 27 months of age in the absence of available specific drug therapy.

Touch and olfaction/taste differentiate children carrying a 16p11.2 deletion from children with ASD

Background

Sensory processing atypicalities are frequent in Autism Spectrum Disorder (ASD) and neurodevelopmental disorders (NDD). Different domains of sensory processing appear to be differentially altered in these disorders. In this study, we explored the sensory profile of two clinical cohorts, in comparison with a sample of typically developing children.

Methods

Behavioral responses to sensory stimuli were assessed using the Sensory Processing Measure (parent-report questionnaire). We included 121 ASD children, 17 carriers of the 16p11.2 deletion (Del 16p11.2) and 45 typically developing (TD) children. All participants were aged between 2 and 12 years. Additional measures included the Tactile Defensiveness and Discrimination Test-Revised, Wechsler Intelligence Scales and Autism Diagnostic Observation Schedule (ADOS-2). Statistical analyses included MANCOVA and regression analyses.

Results

ASD children score significantly higher on all SPM subscales compared to TD. Del16p11.2 also scored higher than TD on all subscales except for tactile and olfactory/taste processing, in which they score similarly to TD. When assessing sensory modulation patterns (hyper-, hypo-responsiveness and seeking), ASD did not significantly differ from del16p11.2. Both groups had significantly higher scores across all patterns than the TD group. There was no significant association between the SPM Touch subscale and the TDDT-R.

Limitations

Sensory processing was assessed using a parent-report questionnaire. Even though it captures observable behavior, a questionnaire does not assess sensory processing in all its complexity. The sample size of the genetic cohort and the small subset of ASD children with TDDT-R data render some of our results exploratory. Divergence between SPM Touch and TDDT-R raises important questions about the nature of the process that is assessed.

Conclusions

Touch and olfaction/taste seem to be particularly affected in ASD children compared to del16p11.2. These results indicate that parent report measures can provide a useful perspective on behavioral expression. Sensory phenotyping, when combined with neurobiological and psychophysical methods, might have the potential to provide a better understanding of the sensory processing in ASD and in other NDD.

Intrauterine Growth Restriction and Hypertrophic Cardiomyopathy as Prenatal Ultrasound Findings in a Case of Leprechaunism

Donohue syndrome (leprechaunism; OMIM *246200) is a rare and often lethal autosomal recessive disease caused by mutations in the INSR gene. We report the case of a 29-year-old pregnant woman, primigravida, who was referred at 33 weeks of gestation for severe intrauterine growth restriction (IUGR). Ultrasound examination found severe IUGR associated with an obstructive hypertrophic cardiomyopathy (HCM), confirmed postnatally. The newborn's blood glucose level fluctuated from fasting hypoglycemia to postprandial hyperglycemia. The infant was found to be homozygous for a novel missense pathogenic variant, c.632C>T (p.T211l), in exon 2 of the INSR gene, predicted to result in an abnormal insulin receptor. To our knowledge, this is the first report of leprechaunism being revealed by IUGR and HCM during the prenatal period. Clinicians should keep in mind that the association of these prenatal signs could indicate leprechaunism and specific early neonatal management could be proposed, in particular with recombinant human insulin-like growth factor-I.

NCKAP1 Disruptive Variants Lead to a Neurodevelopmental Disorder with Core Features of Autism

NCKAP1/NAP1 regulates neuronal cytoskeletal dynamics and is essential for neuronal differentiation in the developing brain. Deleterious variants in NCKAP1 have been identified in individuals with autism spectrum disorder (ASD) and intellectual disability; however, its clinical significance remains unclear. To determine its significance, we assemble genotype and phenotype data for 21 affected individuals from 20 unrelated families with predicted deleterious variants in NCKAP1. This includes 16 individuals with de novo (n = 8), transmitted (n = 6), or inheritance unknown (n = 2) truncating variants, two individuals with structural variants, and three with potentially disruptive de novo missense variants. We report a de novo and ultra-rare deleterious variant burden of NCKAP1 in individuals with neurodevelopmental disorders which needs further replication. ASD or autistic features, language and motor delay, and variable expression of intellectual or learning disability are common clinical features. Among inherited cases, there is evidence of deleterious variants segregating with neuropsychiatric disorders. Based on available human brain transcriptomic data, we show that NCKAP1 is broadly and highly expressed in both prenatal and postnatal periods and demostrate enriched expression in excitatory neurons and radial glias but depleted expression in inhibitory neurons. Mouse in utero electroporation experiments reveal that Nckap1 loss of function promotes neuronal migration during early cortical development. Combined, these data support a role for disruptive NCKAP1 variants in neurodevelopmental delay/autism, possibly by interfering with neuronal migration early in cortical development.

Identification of TSC1 or TSC2 mutation limited to the tumor in three cases of solitary subependymal giant cell astrocytoma using next-generation sequencing technology

PURPOSE

Subependymal giant-cell astrocytomas (SEGAs) are low grade intraventricular tumors typically found in patients with tuberous sclerosis complex (TSC). The occurrence of SEGA in non TSC patients is very rare and from a genetic point of view these so-called solitary SEGA are thought to result either from somatic mutations in one of the TSC genes (TSC1 or TSC2) limited to the tumor, or be part of a "forme fruste" of TSC with somatic mosaicism. We report on three new cases of solitary SEGA with germline and somatic mutation analysis.

METHODS

We retrospectively analyzed TSC genes in three patients with a solitary SEGA using next-generation sequencing technique.

RESULTS

In the three patients, a somatic mutation of TSC1 or TSC2 was found only in the tumor cells: one patient had a TSC1 heterozygote mutation, involving the natural acceptor splicing site of intron 15 (c.1998-1G > A (p.?). Two patients had a TSC2 mutation located in the canonical splicing donor site of intron 5 (c.599 + 1G > A) in 70% of the alleles in one patient and in exon 9: c.949_955dup7 (p.V319DfxX21) in 25 of the alleles in the second patient. No other TSC mutations were found in patient's blood or tumor and those identified mutations were absent in blood DNA from parents and siblings.

CONCLUSION

We therefore conclude that solitary SEGA can occur with a TSC1 or TSC2 mutation limited to the tumor in patients without TSC.

Novel truncating and missense variants extending the spectrum of EMC1-related phenotypes, causing autism spectrum disorder, severe global development delay and visual impairment

The EMC1 gene, located on 1p36.13, encodes the subunit 1 of the endoplasmic reticulum-membrane protein complex, a highly conserved and ubiquitous multiprotein transmembrane complex. Pathogenic monoallelic and biallelic variants in EMC1 in humans have been reported only in six families, causing isolated visual impairment or in association with psychomotor retardation and cerebellar atrophy. We report a ten-year-old boy, born to unrelated parents, with early-onset severe global development delay due to novel EMC1 biallelic pathogenic variants. A truncating variant, p.(Tyr378*) and a missense variant, p.(Phe953Ser), located in exon 11 and 23 of EMC1 gene respectively, have been found by reanalysis of exome sequencing data. The proband's phenotype included several signs that overlap with the phenotype of previously reported patients, associating severe global developmental delay, abnormal ophthalmological examination, and postnatal slow-down of the head circumference growth. Some distinguishing clinical signs were observed in comparison to patients from literature, such as autism spectrum disorder, absence of seizures, scoliosis or facial dysmorphic features, thus extending the spectrum of EMC1-related phenotypes. Similarly, brain MRI, performed at 2 years, showed normal cerebellar volume and structure, whereas cerebellar atrophy was described in literature. Moreover, difficulties of clinical differential diagnosis between EMC1-associated disease and other etiologies of global development delay support the importance of large-scale genetic investigations. Our diagnostic approach, through reanalysis of exome sequencing data, highlights the importance of reconsidering initial negative results for patients with a strong suspicion of genetic disease, and to update analytic pipelines in order to improve the diagnostic yield of exome sequencing.

Supravalvular Aortic Stenosis Caused by a Familial Chromosome 7 Inversion Disrupting the ELN Gene Uncovered by Whole-Genome Sequencing

Apparently, balanced chromosomal rearrangements usually have no phenotypic consequences for the carrier. However, in some cases, they may be associated with an abnormal phenotype. We report herein the case of a 4-year-old boy presenting with clinically isolated supravalvular aortic stenosis (SVAS). No chromosomal imbalance was detected by array CGH. The karyotype showed a balanced paracentric chromosome 7 inversion. Breakpoint characterization using paired-end whole-genome sequencing (WGS) revealed an ELN gene disruption in intron 1, accounting for the phenotype. Family study showed that the inversion was inherited, with incomplete penetrance. To our knowledge, this is the first case of a disruption of the ELN gene characterized by WGS. It contributes to refine the genotype-phenotype correlation in ELN disruption. Although this disruption is a rare etiology of SVAS, it cannot be detected by the diagnostic tests usually performed, such as array CGH or sequencing methods (Sanger, panel, or exome sequencing). With the future perspective of WGS as a diagnostic tool, it will be important to include a structural variation analysis in order to detect balanced rearrangements and gene disruption.

Whole genome paired-end sequencing elucidates functional and phenotypic consequences of balanced chromosomal rearrangement in patients with developmental disorders

BACKGROUND

Balanced chromosomal rearrangements associated with abnormal phenotype are rare events, but may be challenging for genetic counselling, since molecular characterisation of breakpoints is not performed routinely. We used next-generation sequencing to characterise breakpoints of balanced chromosomal rearrangements at the molecular level in patients with intellectual disability and/or congenital anomalies.

METHODS

Breakpoints were characterised by a paired-end low depth whole genome sequencing (WGS) strategy and validated by Sanger sequencing. Expression study of disrupted and neighbouring genes was performed by RT-qPCR from blood or lymphoblastoid cell line RNA.

RESULTS

Among the 55 patients included (41 reciprocal translocations, 4 inversions, 2 insertions and 8 complex chromosomal rearrangements), we were able to detect 89% of chromosomal rearrangements (49/55). Molecular signatures at the breakpoints suggested that DNA breaks arose randomly and that there was no major influence of repeated elements. Non-homologous end-joining appeared as the main mechanism of repair (55% of rearrangements). A diagnosis could be established in 22/49 patients (44.8%), 15 by gene disruption (KANSL1, FOXP1, SPRED1, TLK2, MBD5, DMD, AUTS2, MEIS2, MEF2C, NRXN1, NFIX, SYNGAP1, GHR, ZMIZ1) and 7 by position effect (DLX5, MEF2C, BCL11B, SATB2, ZMIZ1). In addition, 16 new candidate genes were identified. Systematic gene expression studies further supported these results. We also showed the contribution of topologically associated domain maps to WGS data interpretation.

CONCLUSION

Paired-end WGS is a valid strategy and may be used for structural variation characterisation in a clinical setting.

Complex Compound Inheritance of Lethal Lung Developmental Disorders Due to Disruption of the TBX-FGF Pathway

Primary defects in lung branching morphogenesis, resulting in neonatal lethal pulmonary hypoplasias, are incompletely understood. To elucidate the pathogenetics of human lung development, we studied a unique collection of samples obtained from deceased individuals with clinically and histopathologically diagnosed interstitial neonatal lung disorders: acinar dysplasia (n = 14), congenital alveolar dysplasia (n = 2), and other lethal lung hypoplasias (n = 10). We identified rare heterozygous copy-number variant deletions or single-nucleotide variants (SNVs) involving TBX4 (n = 8 and n = 2, respectively) or FGF10 (n = 2 and n = 2, respectively) in 16/26 (61%) individuals. In addition to TBX4, the overlapping ∼2 Mb recurrent and nonrecurrent deletions at 17q23.1q23.2 identified in seven individuals with lung hypoplasia also remove a lung-specific enhancer region. Individuals with coding variants involving either TBX4 or FGF10 also harbored at least one non-coding SNV in the predicted lung-specific enhancer region, which was absent in 13 control individuals with the overlapping deletions but without any structural lung anomalies. The occurrence of rare coding variants involving TBX4 or FGF10 with the putative hypomorphic non-coding SNVs implies a complex compound inheritance of these pulmonary hypoplasias. Moreover, they support the importance of TBX4-FGF10-FGFR2 epithelial-mesenchymal signaling in human lung organogenesis and help to explain the histopathological continuum observed in these rare lethal developmental disorders of the lung.

Prenatal microarray comparative genomic hybridization: Experience from the two first years of activity at the Lyon university-hospital

OBJECTIVES

This study aims to describe how microarray comparative genomic hybridization (aCGH) has shifted to become a prenatal diagnosis tool at the Lyon university-hospital.

MATERIALS AND METHODS

This retrospective study included all patients who were referred in the 3 pluridisciplinary centers for prenatal diagnosis of the Lyon university-hospital and who received a prenatal aCGH between June 2013 and June 2015. aCGH was systematically performed in parallel with a karyotype, using the PréCytoNEM array design.

RESULTS

A total of 260 microarrays were performed for the following indications: 249 abnormal ultrasounds (95.8%), 7 characterizations of chromosomal rearrangements (2.7%), and 4 twins with no abnormal ultrasounds (1.5%). With a resolution of 1 mega base, we found 235 normal results (90.4%), 23 abnormal results (8.8%) and 2 non-returns (0.8%). For the chromosomal rearrangements visible on the karyotype, aCGH identified all of the 12 unbalanced rearrangements and did not identify the 2 balanced rearrangements. Among the fetuses with normal karyotypes, 11 showed abnormal microarray results, corresponding to unbalanced cryptic chromosomal rearrangements (4.2%).

CONCLUSION

Transferring aCGH to a prenatal diagnosis at the Lyon university-hospital has increased the detection rate of chromosomal abnormalities by 4.2% compared to the single karyotype.

A New Observation of an Atypical and Severe Variant of the Guillain-Barre Syndrome in a Child: Remaining Challenges for Diagnosis, Nosologic Classification, and Therapeutic Course

Guillain-Barré syndrome is a rare acute polyradiculoneuropathy. Several variants and unusual presentations have been described, particularly in pediatrics. In most cases, making an early diagnosis is challenging due to the treatments that consist in the rapid administration of intravenous immunoglobulin or plasma exchange. The authors present the case of a 7-year-old boy with an atypical and severe axonal Guillain-Barré syndrome, associated with Mycoplasma pneumonia. When he was admitted, febrile respiratory failure was the main focus, and then he presented signs of acute polyneuropathy with cranial nerve palsy and brief hyperreflexia. Mechanical ventilation was required for 48 days as well as 2 cycles of intravenous immunoglobulin. The authors describe all the medical challenges that the authors encountered. This case highlights the fact that respiratory distress can be the main clinical symptom in children. This delays the establishment of a correct diagnosis, even more so when neurological manifestations are abundant and unusual.

ZEB2, a new candidate gene for asplenia

Primary asplenia is a rare condition with poorly known etiology. Mowat-Wilson syndrome (MWS) is characterized by typical facial dysmorphisms, intellectual disability, microcephaly, epilepsy and the possible presence of internal organ malformations. It is caused by heterozygous mutations or deletions in the ZEB2 gene. Nearly 180 patients have been reported to date, but only one with asplenia. We report here spleen hypo/aplasia in 4 out of 6 MWS patients, with severe infectious complications for 3 of them. Our report shows that spleen hypo/aplasia is part of the MWS phenotype and makes ZEB2 a possible candidate gene for primary asplenia.

Evidence of pathway-specific basophil anergy induced by peanut oral immunotherapy in peanut-allergic children

BACKGROUND

In Westernized countries, over 1% of the population is allergic to peanuts or tree nuts, which carries a risk of severe allergic reactions. Several studies support the efficacy of peanut oral immunotherapy (OIT) for reducing the clinical sensitivity of affected individuals; however, the mechanisms of this effect are still being characterized. One mechanism that may contribute is the suppression of effector cells, such as basophils. Basophil anergy has been characterized in vitro as a pathway-specific hyporesponsiveness; however, this has not been demonstrated to occur in vivo.

OBJECTIVE

To evaluate the hypothesis that basophil anergy occurs in vivo due to chronic allergen exposure in the setting of a clinical oral immunotherapy trial.

METHODS

Samples of peripheral blood were obtained from subjects during a placebo-controlled clinical trial of peanut OIT. Basophil reactivity to in vitro stimulation with peanut allergen and controls was assessed by the upregulation of activation markers, CD63 and CD203c, measured by flow cytometry.

RESULTS

The upregulation of CD63 following stimulation of the IgE receptor, either specifically with peanut allergen or non-specifically with anti-IgE antibody, was strongly suppressed by active OIT. However, OIT did not significantly suppress this response in basophils stimulated by the distinct fMLP receptor pathway. In the subset of subjects with egg sensitization, active peanut OIT also suppressed CD63 upregulation in response to stimulation with egg allergen. Allergen OIT also suppressed the upregulation of CD203c including in response to stimulation with IL-3 alone.

CONCLUSION

Peanut OIT induces a hyporesponsive state in basophils that is consistent with pathway-specific anergy previously described in vitro. This suggests the hypothesis that effector cell anergy could contribute to clinical desensitization.

Effect of surface roughness, biofilm coverage and biofilm structure on the electrochemical efficiency of microbial cathodes

Biofilms of Geobacter sulfurreducens were formed under chronoamperometry at -0.5 V and -0.6 V vs. Ag/AgCl on stainless steel cathodes and tested for fumarate reduction. Increasing the surface roughness Ra from 2.0 μm to 4.0 μm increased currents by a factor of 1.6. The overall current density increased with biofilm coverage. When the current density was calculated with respect to the biofilm-coated area only, values up to 280 A/m(2) were derived. These values decreased with biofilm coverage and indicated that isolated cells or small colonies locally provide higher current density than dense colonies. Steel composition affected the current values because of differences in biofilm structure and electron transfer rates. Biofilms formed under polarisation revealed better electrochemical characteristics than biofilm developed at open circuit. This work opens up new guidelines for the design of microbial cathodes: a uniform carpet of isolated bacteria or small colonies should be targeted, avoiding the formation of large colonies.

Contribution of Ara h 2 to peanut-specific, immunoglobulin E-mediated, cell activation

BACKGROUND

Ara h 2 is a potent peanut allergen but its contribution to the ability of a crude peanut extract (CPE) to cross-link IgE and activate mast cells has not been rigorously evaluated.

OBJECTIVE

To measure the contribution that Ara h 2 makes to the effector function of a CPE.

METHODS

Ara h 2 was specifically removed from a CPE as demonstrated by immunoblots, 2D gels, and an inhibitory ELISA. Functional assays of sham-treated and Ara h 2-depleted CPEs were performed with RBL SX-38 cells sensitized with IgE from highly peanut-allergic subjects and with naturally sensitized basophils.

RESULTS

Depletion of approximately 99% of the Ara h 2 from the CPE led to an increase in the concentration of the CPE necessary to give 50% of maximal degranulation (EC50) of the SX-38 cells following sensitization with sera that contain anti-Ara h 2 IgE. Assays with a pool of 10 sera showed a small but significant increase in the EC50 following depletion of Ara h 2 (1.65+/-0.15-fold; P<0.05) and assays of seven individual sera showed a similar increase in the average EC50 (1.7+/-0.2-fold; P<0.02). The percent of the anti-peanut IgE that binds Ara h 2 correlated with an increase in the EC50 of the CPE following depletion of Ara h 2 (r=0.83; P<0.02). On the other hand, data from three of these patients studied with a basophil histamine release assay did not show a significant effect of depletion of Ara h 2.

CONCLUSION

Based on its ability to cross-link IgE effectively, Ara h 2 is clearly an important peanut allergen. Its ability to cross-link IgE effectively from a specific serum is related to the proportion of anti-Ara h 2 in that serum but Ara h 2 does not account for a majority of the effector activity of the CPE for any of the sera studied.

The 18 kDa peanut oleosin is a candidate allergen for IgE-mediated reactions to peanuts

BACKGROUND

Peanut allergy is one of the five most frequent food allergies in children and in adults. Recently, we purified and evaluated the allergenicity of peanut oleosins, a family of small-sized proteins involved in the formation of peanut oil bodies.

METHODS

Allergenicity of the purified native protein and of the recombinant protein was tested by Western blot and by IgE-RIA.

RESULTS

We found IgE-binding with oleosin in 3 of 14 sera of patients who had suffered an allergic reaction to peanuts. Two sera reacted weakly against 16-18 kDa proteins corresponding to oleosin monomers, in Western blot. The main reacting bands had a molecular size estimated at approximately 34 kDa, approximately 50 kDa and approximately 68 kDa and could therefore correspond to oleosin oligomers. IgE reactivity was higher in extracts from roasted peanuts. The same phenomenon occurred with crude soybean oil fraction, with two bands of 16.5 and 24 kDa corresponding to monomers, and two bands of 50 kDa and 76 kDa corresponding to dimers and trimers, respectively. The 18 kDa band was observed in the 3 Western blots of a membrane-enriched fraction of recombinant oleosin produced in the Sf9-baculovirus expression system (performed with the 3 patient sera).

CONCLUSIONS

We have characterized a new peanut allergen which belongs to the oleosins, a family of proteins involved in the formation of oil bodies. The protein may be involved in some of the allergic cross-reactions to peanuts and soybeans.

Paracellular transport of avidin saturated or not with biotinylated cobalamin through Caco-2 cell epithelium monolayer

BACKGROUND

The cationic charge of molecules may promote their uptake across epithelia, which are rich in brush border anionic sites. The transport of unsaturated avidin and avidin saturated with a biotinylated compound was investigated across Caco-2 adenocarcinoma cell with fetal enterocyte phenotype.

METHODS

The unsaturated avidin and avidin saturated with either biotin or a biotinyl-cobalamin conjugate (biotinyl-Cbl) were iodinated to follow their transport through the cell monolayer. Their apparent permeability coefficient (Papp) and transepithelial pathway were determined and compared to those for control radiolabeled markers [3H]-mannitol, [125I]-beta-lactoglobulin and [57Co]-cobalamin/intrinsic factor (Cbl/IF).

RESULTS

The Papp of [125I]-avidin estimated at 2.8 x 10(-7) +/- 0.08 cm/s was close to that for mannitol that uses paracellular pathway. The binding of biotin or biotin conjugate to avidin enhanced its tetrameric conformation. The Papp for [125I]-avidin/biotin and [125I]- avidin/biotinyl-Cbl were respectively increased by 2-fold, compared to that for [125I]-avidin and 4-fold, compared to that for [125I]-beta-lactoglobulin and [54Co]-Cbl/IF. The protein was not accumulated in the cell and was found in intact form in the basolateral side, after its transport across the monolayer. Chloroquine (0.66 micromol/ml) did not significantly decrease the Papp for [125I]-avidin/biotinyl-Cbl. Conversely it decreased by 80% the Papp for Cbl/IF, that uses transepithelial pathway.

CONCLUSIONS

Avidin (either saturated or not with biotin and biotinyl-Cbl) was able to cross the monolayer of Caco-2 cell line through a paracellular pathway. This study pointed out the interest for using this protein as a shuttle for increasing the transport rate of biotinylated compounds through fetal epithelial barriers.

Transcytosis and coenzymatic conversion of [(57)Co]cobalamin bound to either endogenous transcobalamin II or exogenous intrinsic factor in caco-2 cells

We have examined the intracellular route, coenzyme conversion and transcytosis rate of [(57) Co]-labeled cobalamin (Cbl) in function of its presentation to the apical side of Caco-2 cells, either free or bound to intrinsic factor (IF). The free-presented Cbl was progressively bound to endogenous transcobalamin II (TCII) which may stem, in part, from a basolateral to apical passage. Its transcytosis was TCII-mediated as it was abolished when antibodies to TCII were added to the apical medium. The apparent permeability coefficient (P(app)) was estimated at 20.8+/-3.6, 103.5+/-17.7, 0.9+/-0.3 x 10(-5) cm/h for TCII-Cbl, IF-Cbl and haptocorrin-Cbl, respectively. Chloroquine inhibited the transcytosis rate of both TCII and IF-bound Cbl in a dose-dependent manner. Approximately 80% of apical Cbl, bound to either exogenous IF or endogenous TCII, was transported to the basolateral side as intact cyano[(57)Co]Cbl whereas the remainder was converted into Ado-Cbl and CH(3)-Cbl within the cells, as shown by HPLC analyses of a 1,000-g pellet and a 12,000-g supernatant. Coenzymatic conversion was virtually abolished by chloroquine. In conclusion, we suggest that apically presented free Cbl is internalized via TCII-dependent transport. The apically internalized CN-Cbl, bound to either IF or TCII, is processed via an acidic vesicle and part of it is converted to coenzymes, whereas bulk of CN-Cbl is transcytosed intact.

Sodium dodecyl sulphate gel electrophoretic preparation of protein standard human apolipoprotein B-48

Quantitation of plasma apo B-48 is currently performed by densitometric analysis of SDS-PAGE zones stained with Coomassie Brilliant Blue, using standard solutions of purified apo B-48. Here, preparative gel electrophoresis with a continuous elution system was used for purifying apo B-48. A chylomicron fraction was isolated by 107,000 g ultracentrifugation of a chylous ascite. The proteins were delipidated and precipitated in ethanol-diethyl ether (3:1, v/v), subjected to preparative electrophoresis in a 5% polyacrylamide gel and eluted in 0.1% SDS. The peak containing apo B-48 was eluted at a retention time of 445-480 min. The purity of apo B-48 in this fraction was assessed by the detection of a single band (M(r) 260,000) after silver staining and Coomassie staining of 4-15% gradient SDS-PAGE. It was confirmed by the absence of apo B-100 contaminant in Western blot of the purified protein preparation. A linear relationship was observed between the densitometric analysis of SDS-PAGE bands and the apo B-48 in a protein range of 0-3 microg. In conclusion, preparative gel electrophoresis was used in a single step purification of apo B-48 that was adapted to the preparation of a standard solution.

One-step purification of R-phycoerythrin from the red macroalga Palmaria palmata using preparative polyacrylamide gel electrophoresis

Phycoerythrin is a major light-harvesting pigment of red algae and cyanobacteria widely used as a fluorescent probe. In this study, phycoerythrin of the red macroalga Palmaria palmata was extracted by grinding the algal sample in liquid nitrogen, homogenisation in phosphate buffer and centrifugation. Phycoerythrin was then purified from this crude extract using preparative polyacrylamide gel electrophoresis (PAGE) with a continuous elution system and detected by its pink colour and fluorescence. The pigment presented a typical spectrum of R-phycoerythrin, with three absorbance maxima at 499, 545 and 565 nm, and displayed a fluorescence maximum at 578 nm. The absorbance ratio A565/A280, a criterion for purity, was 3.2. A single protein of relative molecular mass 240,000 was detected on native-PAGE with silver staining. Sodium dodecyl sulphate-PAGE demonstrated the presence of two major subunits with Mr 20,000 and 21,000, respectively, and a very minor subunit of Mr 30,000. These observations are consistent with the (alphabeta)6gamma subunit composition characteristic of R-phycoerythrin. Phycoerythrin of Palmaria palmata was determined to be present in larger amounts in autumn and showed a good stability up to 60 degrees C and between pH 3.5 and 9.5. In conclusion, phycoerythrin of Palmaria palmata was purified in a single-step using preparative PAGE. Obtaining pure R-phycoerythrin of Palmaria palmata will allow one to evaluate its fluorescence properties for future applications in biochemical techniques.

[21-hydroxylase autoantibodies as a marker of adrenal involvement in patients with autoimmune endocrinopathies]

Autoantibodies against 21-hydroxylase are common in idiopathic Addison's disease. The objective of this study was to determine the frequency of these antibodies in different endocrine autoimmune diseases with or without adrenal insufficiency and to follow up their evolution. We have used a radiobinding assay based on 125-I labeled 21-hydroxylase (21-OH-AB, RSR, UK). Serum samples with 21-hydroxylase antibodies levels equal or greater than 1.0 U/ml were considered as positive. We found these autoantibodies in 21/23 idiopathic Addisonian patients, in 0/18 patients with isolated hypothyroïdism, in 0/6 patients with isolated Grave's disease, in 2/14 patients with isolated ovarian failure, in 1/27 patients with 2 ou more associated autoimmune diseases without adrenal insufficiency. The comparison between patients with or without adrenal insufficiency has shown, for this assay, a sensibility of 91 %, a specificity of 96 %. The 21-hydroxylase autoantibodies were followed up in 4 patients with Addison's disease and showed progressive decreasing levels. We can not exclude that the addisonian sera might become negative for these antibodies after the total destruction of adrenal cortex. In conclusion, the presence of 21-hydroxylase autoantibodies is highly specific for idiopathic Addison's disease and the level of these antibodies decrease with disease duration.

Meningeal involvement in Behçet's disease: MRI

Behçet's disease is a multisystem disease that involves the central nervous system up to half of cases. Presentation with neurologic symptoms occurs in 5% of cases and cerebral venous thrombosis is one of its major manifestations. A feature not previously reported is progressive meningeal thickening with involvement of both optic nerves. We report a patient with cerebral venous thrombosis, meningeal thickening and contrast enhancement on MRI. This patient had two other unusual features: positive antineutrophil cytoplasmic antibodies and later development of central diabetes insipidus.

Isolation and characterization of proteic allergens in refined peanut oil

Allergic reactions to peanut oil are very much debated, even if the responsibility of peanut oil has been evoked in several cases of adverse reactions, including death related to severe asthma. The aim of the present study was to investigate the presence of allergenic proteins in peanut oil. Proteins were extracted from commercial refined peanut oil, with a relative content in the order of 0.1-0.2 microg per g of oil, and molecular sizes ranging from 14 up to 76kDa in SDS-PAGE. Eight protein bands were systematically observed in crude, neutralized and refined oils, with a molecular mass ranging from approximately 14 to 76 kDa, including one at 18 kDa which was identified by Western blot performed with serum from two allergic patients. The protein extract gave positive IgE-RIA with patient sera, positive in vitro leucocyte histamine release tests and positive skin-prick tests in allergic patients. The allergenic protein was purified by HPLC and [125I] iodide-labelled. It had an isoelectric point at 4.5 in isoelectrofocusing. In conclusion, we have demonstrated the presence of allergenic proteins in crude and refined peanut oil. These proteins are the same size as two allergens previously described in peanut protein extracts.

Characterization of the oligomeric behavior of a 16.5 kDa peanut oleosin by chromatography and electrophoresis of the iodinated form

Oleosins are amphipathic proteins associated with oil bodies in seeds. We purified the major 16,500 peanut oleosin by preparative SDS-PAGE. Autoradiography after SDS-PAGE separation of the iodinated oleosin revealed covalently bound oligomers with Mr of 21,000, 33,000, 44,000 and 51,000. The strong capacity of these oligomers to form aggregates and to be incorporated into large-sized detergent micelles was demonstrated by gel permeation and isoelectric focusing. A 50% ethanol concentration was necessary to elute the 16,500 oleosin from octyl groups in hydrophobic interaction chromatography showing its natural tendency to interact with lipid acyl chains. This oligomerization behavior in aqueous solution is an indirect reflection of the interactions that occur in the oil body.

Purification of a 41 kDa cod-allergenic protein

Cod fish is one of the foods most frequently involved in allergy. Only the cod allergen Gad c I, a 12.3 kDa parvalbumin, has been purified and characterized. Recently, we have detected allergen bands which have not previously been described, in particular a 41 kDa protein, by Western-blot. In the present work, this protein has been purified from a crude cod extract by ammonium sulfate fractionation, hydroxyapatite chromatography and preparative electrophoresis; a single band with an Mr of 41 x 10(3) was found in silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition and the isoelectric point of the protein were determined. The purified protein (p41) was shown to bind specifically to reaginic IgE from sera of cod-allergic individuals and to a monoclonal anti-parvalbumin which recognizes specifically the first calcium binding site of parvalbumins. p41 may therefore contain a calcium binding site corresponding to an IgE-epitope similar to that of Gad c I.

Role of platelet-activating factor (PAF) and prostaglandins in colonic motor and secretory disturbances induced by Escherichia coli endotoxin in conscious rats

The involvement of prostaglandins (PGs) and platelet-activating factor (PAF) in the effects of Escherichia coli endotoxin on colonic motility, transit time, and fecal dry matter (DM) in rats were evaluated in this study. Myoelectric activity was investigated in a first group of male Wistar rats chronically implanted with intraparietal nichrome electrodes in the proximal colon. A second group of animals was chronically fitted with an intracolonic catheter (+2 cm from the cecocolonic junction); colonic transit time was then calculated as the Mean Retention Time (MRT) of 51Cr chromate sodium (1 microCi 0.1ml) administered through the intracolonic catheter and determined in the faeces collected at 1 hour interval on a conveyor belt. Fecal DM was measured after 24h dessication at 103 degrees C. E. coli endotoxin (50 micrograms/kg ip) increased the frequency of colonic contractions and decreased both colonic MRT and fecal DM. PAF (25 micrograms/kg ip) also decreased colonic MRT and fecal DM, and increased the frequency of colonic contractions. BN 50730 (10 mg/kg ip), a specific PAF receptor antagonist, blocked the effects of PAF and reduced those of endotoxin on colonic motility and transit time, but did not affect either the endotoxin- or the PAF-induced fecal DM decrease. Indomethacin (10 mg/kg ip) and SC 19220 (5 mg/kg ip) reduced the increased frequency of colonic contractions induced by endotoxin and PAF, and antagonized their effects on MRT and fecal DM. These results indicate that 1) E. coli endotoxin increases both colonic motility and transit, and decreases fecal DM, 2) PAF displays similar effects, 3) the action of endotoxin on colonic motility and transit is partly mediated by PAF and PGs while its secretory effects only depend upon PGs generation.

Platelet-activating factor and interleukin 1 are involved in colonic dysmotility in experimental colitis in rats

BACKGROUND

Intracolonic administration of trinitrobenzene sulfonic acid (TNBS) to rats produces chronic colitis associated with an increased release of eicosanoids, platelet-activating factor (PAF), and interleukins.

METHODS

Motor effects of TNBS on proximal colon were evaluated electromyographically in rats. Mediator involvement was investigated using eicosanoids and PAF antagonists.

RESULTS

The colonic myoelectrical activity was 59 +/- 17 spike bursts per hour lasting 6.9 +/- 1.3 seconds. Two to eight days after TNBS treatment, spike-burst duration was significantly (P < 0.05) higher, with a maximal 1.5-4-fold enhancement at day 3. These alterations were significantly (P < 0.05) reduced by daily treatment with MK-886, a 5-lipoxygenase inhibitor (10 mg/kg, orally), whereas indomethacin (1 mg/kg per day, intramuscularly) was ineffective. At day 3, RP55778, a PAF antagonist (45, 60 mg/kg, intraperitoneally), and rIRAP, an interleukin 1 antagonist (0.3 mg/kg, intraperitoneally) but not KT1-32, a thromboxane A2 antagonist (30, 60 mg/kg orally), nor SKF104,353, a leukotriene D4 antagonist (2, 4 mg/kg, orally), significantly (P < 0.05) reduced the TNB-induced motor effects.

CONCLUSION

TNBS-induced colitis in rats involves a delayed long-lasting dysmotility involving PAF, interleukin 1, and some leukotrienes but not leukotriene D4, thromboxane A2, or other cyclo-oxygenase products.

[Primary intraventricular hemorrhage in a patient with unilateral moyamoya disease]

According to the diagnostic criteria currently in use, the so-called "unilateral" forms of the moyamoya disease, or rather those in which the disorders of the disease itself--such as occlusion of the internal supraclinoid carotid artery or its terminal branches and development of abnormal collateral circulation in the region of the basal ganglia--are only found in one hemisphere and should be considered as "probable" forms of the disease with a much lower incidence than the bilateral or "defined" forms of the same. One patient with a primary intraventricular hemorrhage (PIVH) in whom an occlusion of the right internal carotid artery was angiographically demonstrated and in whom collateral type moyamoya circulation was found as was the presence of an aneurysm in the right coroid territory is presented. The association of PIVH, unilateral moyamoya disease and aneurysm is infrequent in the literature, with the origin of the bleeding, in some cases, having been attributed to rupture of the aneurysm. Since angiographic control was not available in the patient presented it cannot be excluded that the aneurysm was really a pseudoaneurysm therefore being a consequence, rather than a cause, of the arterial rupture. Thus one of the other mechanisms proposed must be invoked to explain the pathogenesis of the PIVH: rupture of a perforating artery or of a microaneurysm located in the subependimary periventricular region. The treatment recommended for these case of PIVH associated to aneurysm is chirurgical if persistence is demonstrated in successive arteriographies.

Mouse macrophage receptor for acetylated low density lipoprotein: demonstration of a fully functional subunit in the membrane and with purified receptor

The functional molecular mass of the macrophage receptor for acetylated low density lipoprotein (Ac-LDL) was determined in membranes by radiation inactivation analysis. Membranes from tumors induced by the mouse macrophage cell line P388D1 were frozen and irradiated with high-energy electrons. Residual binding activity indicated a minimum functional molecular mass of 35,000 Da, considerably smaller than the active 260,000 M(r) protein seen on ligand blots under nonreducing conditions. Scatchard analysis of receptor binding gave no evidence of partially inactivated molecules. The receptor protein, purified by affinity chromatography and preparative gel electrophoresis, was incubated with dithiothreitol (0.1-100 mM) and retested for binding activity. Active subunits of 158,000 and 80,000 M(r) could be demonstrated by ligand blotting, with quantitative conversion of binding activity to the 80,000 M(r) species at 10 mM dithiothreitol. At 100 mM dithiothreitol, all binding activity was lost. Further size reduction was not detected by silver staining. These data suggest that the isolated mouse macrophage Ac-LDL receptor is a trimer with one class of SH groups involved in trimerization and another in the actual binding site. The monomeric species is fully active in vitro under mild reducing conditions. The radiation inactivation data also suggest that each monomeric unit is fully active and capable of functioning independently in the binding of ligands in the membrane.

Leukotriene D4 participates in colonic transit disturbances induced by intracolonic administration of trinitrobenzene sulfonic acid in rats

The effects of colonic inflammation induced by trinitrobenzene sulfonic acid and influence of previous treatment with specific antagonists of inflammatory mediators (platelet-activating factor, leukotrienes, prostaglandins, and thromboxanes) on colonic transit were examined in conscious rats which were permanently fitted with an intracolonic catheter inserted into the proximal colon. Colonic inflammation was induced by intracolonic administration of trinitrobenzene acid (80 mg/kg) in 50% ethanol. Colonic transit time was evaluated by intracolonic administration of a radiolabeled marker [( 51Cr]sodium chromate) and collection of the feces per hour on a conveyor belt. Excretion of the marker was then plotted vs. time, permitting calculations of the times elapsed to recover 25%, 50%, and 75% of the marker injected (T25, T50, and T75, respectively). In control (saline) animals, excretion of the marker described a regular sigmoid curve with 50% of the marker recovered at 6.92 +/- 0.40 hours after intracolonic administration (T25 = 6.4 +/- 0.43 hours; T75 = 7.49 +/- 0.39 hours). Ethanol (vehicle), 50%, did not modify the profile of marker recovery. On the contrary, single intracolonic administration of trinitrobenzene sulfonic acid/ethanol induced a biphasic response consisting of an early pool of radiolabeled feces (T25 = 4.03 +/- 0.55 hours) with a delayed total one (T50 = 11.74 +/- 0.83 hours; T75 = 13.70 +/- 0.49 hours). Antagonists of the leukotriene pathway, i.e., MK = 886, a lipoxygenase inhibitor, and SKF 104,353 and SR 2640, two different leukotriene D4 receptor antagonists, blocked the effects of trinitrobenzene sulfonic acid on colonic transit time and restored a control profile of radiolabeled marker excretion. In contrast, indomethacin, a cyclooxygenase inhibitor, and SC 19220, a specific prostaglandin E2 receptor antagonist, were inefficient in blocking the effects of trinitrobenzene sulfonic acid on colonic transit time. Specific thromboxane A2 receptor antagonists, KT1-32 and GR 32191B, did not show any improvement in colonic transit after trinitrobenzene sulfonic acid administration. Previous injection of the specific platelet-activating factor receptor antagonists, BN 52021 or BN 50730, was also unable to restore a normal marker excretion profile after administration of trinitrobenzene sulfonic acid. It is concluded that the alterations of colonic transit immediately observed after intracolonic trinitrobenzene sulfonic acid administration are mediated through the release of leukotriene D4. In contrast, platelet-activating factor, prostaglandins, and thromboxanes are not involved in the mediation of these transit disturbances.

Myoelectric intestinal disturbances in Escherichia coli endotoxic shock in rats. Involvement of platelet-activating factor

Administration of BN 52021 (50 mg/kg i.v.), a specific antagonist of platelet-activating factor (PAF), significantly reduced the intestinal myoelectric disturbances induced by E. coli endotoxin injection (50 micrograms/kg i.v.) by 62%. Thus, PAF may be involved in the intestinal motor alterations observed in endotoxic shock. When given in combination with indomethacin (10 mg/kg i.p.), BN 52021 inhibited endotoxic shock intestinal disturbances. Indomethacin alone also reduced PAF induced (25 micrograms/kg i.p.) disruption of migrating myoelectric complexes. Endotoxins may act on intestinal motility via release of endogenous PAF and prostaglandins, the effects of PAF being mediated through the release of prostaglandins.

Role of free radicals and platelet-activating factor in the genesis of intestinal motor disturbances induced by Escherichia coli endotoxins in rats

The effects of IV administration of Escherichia coli endotoxin on intestinal myoelectric activity was investigated in conscious fasted rats chronically implanted with nichrome electrodes in the duodenojejunum. These effects were compared with those of platelet-activating factor and were evaluated in animals pretreated with a specific platelet-activating factor antagonist, BN 52021, indomethacin, a selective prostaglandin E2 antagonist, SC 19220, and several free radical scavengers. Intravenous administration of endotoxin (E. coli S.O111:B4) at a dose of 50 micrograms/kg suppressed the migrating myoelectric complexes, which were replaced by continuous rhythmic clusters of rapidly propagated spike bursts for 114.7 +/- 19.9 minutes. Intraperitoneal platelet-activating factor (25 micrograms/kg) also inhibited the migrating myoelectric complex pattern for 146.1 +/- 24.1 minutes. Previous IV administration of BN 52021 (50 mg/kg-1) abolished the motor alterations induced by platelet-activating factor and significantly reduced to 43.1 +/- 12.2 minutes those induced by endotoxin (P less than 0.01). Indomethacin (10 mg/kg IP), injected before endotoxin or platelet-activating factor, also significantly reduced the duration of migrating myoelectric complex inhibition to 45.6 +/- 7.8 and 47.7 +/- 8.3 minutes, respectively (P less than 0.01). SC 19220 significantly reduced the effects of platelet-activating factor from 151.8 +/- 26.4 to 67.4 +/- 14.7 min (P less than 0.01). Superoxide dismutase (15,000 U/kg IV) injected before either endotoxin or platelet-activating factor shortened the migrating myoelectric complex inhibition to 45.7 +/- 9.9 and 72.9 +/- 10.4 minutes, respectively (P less than 0.01). Allopurinol and dimethylsulfoxide administered orally at 50 mg/kg 1 hour before endotoxin reduced the migrating myoelectric complex inhibition to 42.5 +/- 6.5 and 38.2 +/- 6.4 minutes, respectively (P less than 0.01). They also reduced platelet-activating factor-induced intestinal myoelectric alterations to 68.5 +/- 10.6 and 31.7 +/- 6.1 minutes, respectively (P less than 0.01). It is concluded that endogenous release of platelet-activating factor is partly responsible for the intestinal motor alterations induced by endotoxin, these effects being also mediated through the release of prostaglandins and free radicals. However, prostaglandins, as well as free radicals, appear to be partly involved in the platelet-activating factor-induced action of E. coli endotoxin on intestinal motility.

Free radicals scavengers attenuate platelet-activating factor (PAF)- and endotoxin-induced intestinal myoelectric disturbances in rats

Pretreatment with radical scavengers significantly reduced the intestinal myoelectric disturbances following either E. coli endotoxin or platelet-activating factor (PAF) injection in the rat indicating that free radicals might be involved in the intestinal motor alterations observed in endotoxin shock and that PAF acts partially via free radical production. Moreover, dimethylsulfoxide (DMSO) was found to be more effective in inhibiting the endoxotin-induced intestinal motor alterations, than superoxide dismutase (SOD) and allopurinol. BN 52021, a specific PAF antagonist, was able to reduce the effects of endotoxin on intestinal motility. However, when BN 52021 was combined with free radical scavengers, no additive effect was observed. It is concluded that free radicals involved in endotoxin-induced intestinal motility alterations are at least in part produced in response to PAF.