An armoured endotracheal tube obstruction in a child

The case of a child whose tracheal tube became obstructed intraoperatively 30 minutes after intubation is reported. It appears that this obstruction was related to the development of bubbles within the walls which expanded upon exposure to nitrous oxide and diffusion of that gas into the bubbles. The authors want to point out the risk of gas diffusion into the walls of the tube and the possibility that repeated sterilization may enhance the development of bubbles. Les auteurs rapportent l’observation d’un enfant de sept mois dont la sonde tracheale s’est obstruée 30 minutes après l’intubation. Cette obstruction était due à l’expansion de bulles incluses dans la paroi du tube après exposition au N₂O et diffusion de celui-ci à l’interieur des bulles. Ils accusent également la stérilisation répétée de la sonde armée (contre l’avis du constructeur) d’avoir favorisé le développement de ces inclusions bulleuses.     

Xenopus muscle development: from primary to secondary myogenesis.

Xenopus myogenesis is characterized by specific features, different from those of mammalian and avian systems both at the cellular level and in gene expression patterns. During early embryogenesis, after the initial molecular signals inducing mesoderm, the myogenic determination factors XMyoD and XMyf-5 are activated in presomitic mesoderm in response to mesoderm-inducing factors. After these first inductions of the myogenic program, forming muscles in Xenopus can have different destinies, some of these resulting in cell death before adulthood. In particular, it is quite characteristic of this species that, during metamorphosis, the primary myotomal myofibers completely die and are progressively replaced by secondary "adult" multinucleated myofibers. This feature offers the unique opportunity to totally separate the molecular analysis of these two distinct types of myogenesis. The aim of this review is to summarize our knowledge on the cellular and molecular events as well as the epigenetic regulations involved in the construction of Xenopus muscles during development.     

Prevalences of herpesviruses DNA sequences in salivary gland biopsies from primary and secondary Sj?gren's syndrome using degenerated consensus PCR primers.

BACKGROUND: Sj?gren's syndrome (SS) is an autoimmune exocrinopathy associated with multiple autoantibodies, lymphocyte infiltration of various organs, and functional deficiency of T cells. Several viruses have been implicated by PCR based studies, but their contribution to the pathophysiology of SS is still controversial. OBJECTIVES: In an attempt to explore the presence of human herpesviruses DNA sequences in salivary glands biopsies from patients suffering of SS, a recently developed strategy based on PCR with consensus degenerated primers that allowed to detect known and eventually unknown herpesviruses was used. STUDY DESIGN: Salivary glands biopsies from 55 patients suffering of primary and SS syndrome were explored by herpesviruses consensus PCR primers and all the PCR products were sequenced. RESULTS: Nine out of 55 salivary glands were positive by PCR and sequence analyses allowed to identify Epstein-Barr virus (EBV) in 6 cases and herpes simplex virus (HSV)-1 in 3 cases. We did not detect any sequences that could be related to a new herpesvirus. CONCLUSION: In view of the good sensitivity of the technique used, our study is not consistent with SS being associated with an unknown herpesvirus. However, our results suggest that EBV and HSV-1 could be implicated in a subset of SS cases and this possibility needs to be explored, to assess the potential benefit of antiviral drugs in some cases.     

ATP-sensitive K+ and Ca2+-activated K+ channels in lamprey ( Petromyzon marinus) red blood cell membrane

The patch-clamp technique was used to demonstrate the presence of ATP-sensitive K(+) channels and Ca(2+)-activated K(+) channels in lamprey ( Petromyzon marinus) red blood cell membrane. Whole-cell experiments indicated that the membrane current under isosmotic (285 mosmol l(-1)) conditions is carried by K(+). In the inside-out configuration an ATP-sensitive K(+) channel (70-80 pS inward, 35-40 pS outward) was present in 35% of patches. Application of ATP to the intracellular side reduced unitary current with half-maximal inhibition in the range 10-100 microM. A block was obtained with 100 microM lidocaine and inhibition was obtained with 0.5 mM barium acetate. A Ca(2+)-activated K(+) channel (25-30 pS inward, 10-15 pS outward) was present in 57% of patches. Inhibition was produced by 10 mM TEA and 500 nM apamin and sensitivity to Ba(2+) was lower than for ATP-sensitive channels. No spontaneous channel activity was recorded in the cell-attached configuration under isotonic conditions. With hypotonic saline 68% of patches showed spontaneous single-channel activity, and, of 75 active patches, 66 cell-attached patches showed channel activity corresponding to Ca(2+)-activated K(+) channels.     

Eucaryotic Expression of the Nucleocapsid Protein Gene of Porcine Circovirus Type 2 and Use of the Protein in an Indirect Immunofluorescence Assay for Serological Diagnosis of Postweaning Multisystemic Wasting Syndrome in Pigs

The purpose of this study was to develop a sensitive, rapid, and inexpensive immunofluorescence assay (IFA) using a recombinant porcine circovirus type 2 (PCV2) nucleocapsid protein for the serological detection of PCV2-specific antibodies in pig sera. The viral nucleocapsid protein encoded by the PCV2 ORF2 gene has recently been identified as the most immunoreactive viral protein that carries type-specific antigenic determinants. The ORF2 sequence of the IAF-2897 strain of PCV2 has been cloned into a pCEP5 eucaryotic expression vector under the control of the cytomegalovirus promoter, downstream of a polyhistidine sequence tag. The recombinant plasmid was used in transfection experiments with human epithelial kidney 293 cells that were further tested, and positive expression of the viral nucleocapsid protein was confirmed by IFA and Western blotting. Strong, specific fluorescence was observed in the nuclei of transfected cells. Test specificity to PCV2 was verified with several related infectious agents. Sensitivity was compared to that of standard IFA using PCV2-infected cells by evaluating the reactivities of 44 field serum samples from pigs on farms with a porcine population suffering from postweaning multisystemic wasting syndrome. The recombinant nucleocapsid-based test was able to detect 15 more positive-testing pigs than the PCV2-based IFA. Therefore, the relative sensitivity of the latter test was estimated at only 57.1% compared to that of the recombinant nucleocapsid-based test. The recombinant fusion protein has been purified by affinity chromatography and is being used to develop further sensitive serological tests.     

Changes in blood lactate and respiratory gas exchange measures in sports with discontinuous load profiles

This study compares two different sport events (orienteering = OTC; tennis = TEC) with discontinuous load profiles and different activity/recovery patterns by means of blood lactate (LA), heart rate (HR), and respiratory gas exchange measures (RGME) determined via a portable respiratory system. During the TEC, 20 tennis-ranked male subjects [age: 26.0 (3.7) years; height: 181.0 (5.7) cm; weight: 73.2 (6.8) kg; maximal oxygen consumption (V˙O₂max): 57.3 (5.1) ml·kg⁻¹·min⁻¹] played ten matches of 50 min. During the OTC, 11 male members of the Austrian National Team [age: 23.5 (3.9) years; height: 183.6 (6.8) cm; weight: 72.4 (3.9) kg; V˙O₂max: 67.9 (3.8) ml·kg⁻¹·min⁻¹] performed a simulated OTC (six sections; average length: 10.090 m). In both studies data from the maximal treadmill tests (TT) were used as reference values for the comparison of energy expenditure of OTC and TEC. During TEC, the average V˙O₂ was considerably lower [29.1 (5.6) ml^·kg^−1·min⁻¹] or 51.1 (10.9)% of VO₂max and 64.8.0 (13.3)% of V˙O₂ determined at the individual anaerobic threshold (IAT) on the TT. The short high-intensity periods (activity/recovery = 1/6) did not result in higher LA levels [average LA of games: 2.07 (0.9) mmol·l⁻¹]. The highest average V˙O₂ value for a whole game was 47.8 ml·kg^−1·min⁻¹ and may provide a reference for energy demands required to sustain high-intensity periods of tennis predominately via aerobic mechanism of energy delivery. During OTC, we found an average V˙O₂ of 56.4 (4.5) ml·kg⁻¹·min⁻¹ or 83.0 (3.8)% of V˙O₂max and 94.6 (5.2)% of V˙O₂ at IAT. In contrast to TEC, LA were relatively high [5.16 (1.5) mmol·l⁻¹) although the average V˙O₂ was significantly lower than V˙O₂ at IAT. Our data suggest that portable RGEM provides valuable information concerning the energy expenditure in sports that cannot be interpreted from LA or HR measures alone. Portable RGEM systems provide valuable assessment of under- or over-estimation of requirements of sports and assist in the optimization and interpretation of training in athletes. Electronic Publication     

The biochemical characterization of E2, a T cell surface molecule involved in rosettes

We have previously identified a molecule on the T cell surface, which, in addition to CD2 is involved in the rosette phenomenon. This is a 32-kDa single polypeptide chain which we have termed E2. The studies reported here show striking patterns on the glycosylation status of E2. It is a heavily sialylated and glycosylated molecule, the sugar moieties accounting for almost half of its relative molecular mass (Mr). It carries no N-linked sugar residues, only O-linked oligosaccharides. Despite heavy glycosylation, the molecule appears to behave homogeneously on gel electrophoresis, both in terms of Mr and pI. Neuraminidase treatment of E2 lowered its Mr to 28 kDa; this was further decreased to 18 kDa after removal of O-linked sugar residues by treatment with O-glycanase. An identical reduction in size was observed after treatment with trifluoromethane sulfonic acid, showing that the molecule carries no detectable N-linked sugar residues. Moreover, endoglycosidase F and endoglycosidase H treatment of either the immunoprecipitates from 125I surface-labeled thymocytes, or of a purified preparation of E2, did not reduce the Mr of E2, nor did tunicamycin treatment of T cells. Two-dimensional gel electrophoresis revealed two discrete spots of acidic pI (4.4 and 4.6) that were still seen after neuraminidase treatment, though they had moderately shifted. Pulse-chase experiments revealed a single 28-kDa precursor form that could have been the unsialylated molecule. Finally, sequencing 14 amino acid residues of the N-terminal side revealed no homology with known proteins. Since the sugar moieties of adhesion protein could play an important role, the results obtained in this study will prove valuable to our understanding of the role exerted by the E2 molecule.     

Multiple cis-regulatory elements and the yeast sulphur regulatory network are required for the regulation of the yeast glutathione transporter, Hgt1p

HGT1 encodes a high-affinity glutathione transporter in the yeast Saccharomyces cerevisiae that is induced under sulphur limitation. The present work demonstrates that repression by organic sulphur sources is under the control of the classic sulphur regulatory network, as seen by the absence of expression in a met4 background. Cysteine appeared to be the principal regulatory molecule, since elevated levels were seen in str4 strains (deficient in cysteine biosynthesis) that could be repressed by elevated levels of cysteine, but not by methionine or glutathione. Investigations into cis-regulatory elements revealed that the previously described motif, a 9-bp cis element, CCGCCACAC, located at the –356 to –364 region of the promoter could in fact be refined to a 7-bp CGCCACA motif that is also repeated at –333 to –340. The second copy of this motif was essential for activity, since mutations in the core region of the second copy completely abolished activity and regulation by sulphur sources. Activity, but not regulation, could be restored by reintroducing an additional copy upstream of the first copy. A third region, GCCGTCTGCAAGGCA, conserved in the HGT1 promoters of the different Saccharomyces spp, was observed at –300 to –285 but, while mutations in this region did not lead to any loss in repression, the basal and induced levels were significantly increased. In contrast to a previous report, no evidence was found for regulation by the VDE endonuclease. The strong repression at the transport level by glutathione seen in strains overexpressing HGT1 was due to a glutathione-dependent toxicity in these cells.     

Variety and complexity of chromosome 17 translocations in neuroblastoma

In neuroblastoma, the most frequent genetic alteration is gain of chromosome arm 17q, which arises from unbalanced translocations. To document these genetic events more precisely, we performed an extensive study of chromosome 17 breakpoints in 27 neuroblastoma cell lines by using a combination of fluorescence in situ hybridization mapping with BAC/PAC clones and allele analysis with polymorphic markers. All cases exhibited one or more unbalanced chromosome 17 translocations, and 15 distinct breakpoint regions could be mapped. This high variability indicates that gene fusion or disruption events are extremely unlikely to account for the underlying oncogenic role of these translocations. However, breakpoints were not randomly distributed, most of them mapping to the proximal part of 17q. As a result of translocations, all cell lines but one exhibited gain of the 53.5 Mb-->qter fragment, bordered proximally by the clone CTC-462L7. The most telomeric breakpoint, flanked by the clone RP11-443M10, defined the 70.9 Mb-->qter fragment as a region of additional gain. In addition to chromosome gains, loss of heterozygosity for the short arm of chromosome 17 was observed in close to half the cases. It was either related to a chromosome 17 monosomy or to a uniparental isodisomy. Finally, in cases with a single normal chromosome 17, we show that the parental origin of the translocated chromosome 17 can be either distinct or identical to that of the normal chromosome. Similarly, multiple translocations within the same cell line can either involve the same or different chromosome 17 homologues, indicating the likely absence of parental origin bias in the generation of these alterations.     

Deep processing activates the medial temporal lobe in young but not in old adults

Age-related impairments in episodic memory have been related to a deficiency in semantic processing, based on the finding that elderly adults typically benefit less than young adults from deep, semantic as opposed to shallow, nonsemantic processing of study items. In the present study, we tested the hypothesis that elderly adults are not able to perform certain cognitive operations under deep processing conditions. We further hypothesised that this inability does not involve regions commonly associated with lexical/semantic retrieval processes, but rather involves a dysfunction of the medial temporal lobe (MTL) memory system. To this end, we used functional MRI on rather extensive groups of young and elderly adults to compare brain activity patterns obtained during a deep (living/nonliving) and a shallow (uppercase/lowercase) classification task. Common activity in relation to semantic classification was observed in regions that have been previously related to semantic retrieval, including mainly left-lateralised activity in the inferior prefrontal, middle temporal, and middle frontal/anterior cingulate gyrus. Although the young adults showed more activity in some of these areas, the finding of mainly overlapping activation patterns during semantic classification supports the idea that lexical/semantic retrieval processes are still intact in elderly adults. This received further support by the finding that both groups showed similar behavioural performances as well on the deep and shallow classification tasks. Importantly, though, the young revealed significantly more activity than the elderly adults in the left anterior hippocampus during deep relative to shallow classification. This finding is in line with the idea that age-related impairments in episodic encoding are, at least partly, due to an under-recruitment of the medial temporal lobe memory system.