Body composition of children with chronic lung disease.
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Adolescent↗
Biomedical subjects
C Dumas
Publications and source records attributed to C Dumas.
HIV-1 Nef protein: purification, crystallizations, and preliminary X-ray diffraction studies.
Human immunodeficiency virus Nef protein accelerates virulent progression of AIDS by its interaction with specific cellular proteins involved in cellular activation and signal transduction. Here we report the purification and crystallization of the conserved core of HIV-1LAI Nef protein in the unliganded form and in complex with the wild-type SH3 domain of the P59fyn protein-tyrosine kinase. One-dimensional NMR experiments show that full-length protein and truncated fragment corresponding to the product of HIV-1 protease cleavage have a well-folded compact tertiary structure. The ligand-free HIV-1 Nefcore protein forms cubic crystals belonging to space group P23 with unit cell dimensions of a = b = c = 86.4 A. The Nef-Fyn SH3 cocrystals belong to the space group P6(1)22 or its enantiomorph, P6(5)22, with unit cell dimensions of a = b = 108.2 A and c = 223.7 A. Both crystal forms diffract to a resolution limit of 3.0 A resolution using synchrotron radiation, and are thus suitable for X-ray structure determination.
Crystallization↗
Natural antisense transcripts of the S locus receptor kinase gene and related sequences in Brassica oleracea.
Gene expression can be inhibited by antisense RNA transcripts. Although this phenomenon is widely used to analyse gene function in plants, the molecular mechanisms involved are poorly understood. One approach to improving our understanding of antisense gene regulation is to analyse the function of endogenous antisense transcripts. To date, only a small number of plant genes have been shown to be transcribed in both directions and limited information is available concerning the role of natural antisense transcripts in plants. In this study, we have identified several natural antisense transcripts which hybridise to probes derived from the S locus receptor kinase gene (SRK). The RNase protection assay and reverse trancriptase-PCR were used to demonstrate that a proportion of the antisense transcripts are encoded directly by SRK. Using different RNase protection probes, regions of the promoter, exon I (which encodes the S domain) and intron I of SRK were shown to be transcribed in an antisense direction. An antisense SRK transcript was shown to inhibit translation of a sense transcript in vitro. The possible role of antisense SRK transcripts in vivo is discussed.
Antisense Elements (Genetics)↗
Randomized trial comparing vigabatrin and hydrocortisone in infantile spasms due to tuberous sclerosis.
Vigabatrin has been shown to be efficient in infants with infantile spasms and tuberous sclerosis, in open studies. In order to compare vigabatrin to oral steroids, a prospective randomized multicenter study was implemented using both drugs as monotherapy in newly diagnosed patients with infantile spasms and tuberous sclerosis. Eleven infants received vigabatrin (150 mg/kg per day) and 11 hydrocortisone (15 mg/kg per day) for 1 month. Spasm free patients continued vigabatrin or progressively stopped hydrocortisone in 1 month, non-responders were crossed to the other drug for a new 2 month-period. All vigabatrin patients (11/11) were spasm-free versus 5/11 hydrocortisone infants (P < 0.01). Seven patients were crossed to vigabatrin (six for inefficacy, one for adverse events) and became also totally controlled. Mean time to disappearance of infantile spasms was 3.5 days on vigabatrin versus 13 days on hydrocortisone (P < 0.01). Five patients exhibited side effects on vigabatrin but nine on hydrocortisone (P = 0.006). Vigabatrin should therefore be considered as the first choice treatment for infantile spasms due to tuberous sclerosis.
Anticonvulsants↗
Multicentre clinical evaluation of vigabatrin (Sabril) in mild to moderate partial epilepsies. French Neurologists Sabril Study Group.
Vigabatrin (VGB) has been shown through several studies to be safe and effective as add-on therapy, particularly for the treatment of partial seizures in patients with severe epilepsies followed for years in hospital-based clinics. We now report additional clinical experience with VGB arising from an open trial of add-on VGB therapy in patients with relatively few seizures followed by qualified neurologists in private practice (the French Neurologists Sabril Study Group). VGB was administered to 397 patients aged 12-74 years (mean age = 37.5 +/- 13.8 years) who presented with no more than seven partial seizures of any type per month during a 3-month baseline period (mean number of seizures = 3.7 +/- 1.9/month). Simple partial seizures were reported in 121 (30.5%) patients, complex partial seizures in 282 (71.0%) and seizures with secondary generalization were reported in 111 (28.0%). The mean number of associated antiepileptic drugs (AEDs) was 1.9 +/- 0.9 and the mean dose of VGB was 2.21 +/- 0.64 g/day. Following introduction of VGB, 53 (13.4%) became seizure-free and remained so during the whole trial. During the fourth month of treatment, 158 patients (39.8%) had no seizures at all and a further 69 (17.4%) had their seizure frequency reduced by more than 50%. Secondary generalization was controlled during the whole period of treatment in 55 out of 97 patients (56.7%), 17 of which remained free of all types of partial seizures. VGB showed a good tolerability profile; adverse experiences more frequently reported were drowsiness and sleep disturbances. No action was necessary in the great majority of cases; the dose was reduced in 26 (6.5%) and VGB was discontinued in 32 (8%) patients. These data provide additional evidence that VGB can be used safely early on to treat patients with mild to moderate partial epilepsies. Secondary generalization was controlled in the majority of patients. Factors associated with the everyday clinical use of VGB, that resulted from a series of organized meetings with the investigators, are discussed.
Adolescent↗
ZmEsr, a novel endosperm-specific gene expressed in a restricted region around the maize embryo.
A novel endosperm-specific gene named Esr (embryo surrounding region) has been isolated by differential display between early developmental stages of maize endosperms and embryos. It is expressed in a restricted region of the endosperm, surrounding the entire embryo at early stages (4 to 7 days after pollination, DAP) and ever-decreasing parts of the suspensor at subsequent stages. The expression starts at 4 DAP and is maintained until at least 28 DAP. A minimum of three Esr genes are present in the maize genome and at least two of them map to the short arm of chromosome 1 at position 56. The Esr genes contain no introns and show no significant nucleotide or amino acid sequence homologies to sequences in the databases. The open reading frames encode basic proteins of 14 kDa with presumptive signal peptides at their N-terminal followed by a hypervariable and a conserved region. The gene product may play a role in the nutrition of the developing embryo or in the establishment of a physical barrier between embryo and endosperm.
Amino Acid Sequence↗
B chromosome behavior in maize pollen as determined by a molecular probe.
The B chromosomes of maize typically undergo nondisjunction during the second microspore division (generative cell division). When the microspore nucleus contains only one B chromosome, two kinds of sperm result, one with two B chromosomes and one with no B chromosomes. The sperm with the B chromosomes preferentially fertilizes the egg cell. Previous studies of these phenomena have been limited to genetic analysis and chromosome spreads. In this study we show that a B chromosome-specific probe can be used with fluorescence in situ hybridization (FISH) analysis to detect the presence, location, and frequency of B chromosomes in intact interphase nuclei within mature pollen of maize. Using genetic line TB-10L18, our results indicate that nondisjunction of the B centromere occurs at an average frequency of 56.6%, based on four plants and 1306 pollen grains analyzed. This is consistent with the results of genetic studies using the same B-A translocation. In addition, our results suggest that B chromosome nondisjunction can occur during the first microspore division. Spatial distribution of the B chromosome-specific probe appears to be largely confined to one tip of the sperm nucleus, and a DNA fragment found outside the pollen nuclei often hybridizes to the B chromosome-specific probe.
Biotinylation↗
Rapid induction by wounding and bacterial infection of an S gene family receptor-like kinase gene in Brassica oleracea.
A receptor-like kinase, SRK, has been implicated in the autoincompatible response that leads to the rejection of self-pollen in Brassica plants. SRK is encoded by one member of a multigene family, which includes several receptor-like kinase genes with patterns of expression very different from that of SRK but of unknown function. Here, we report the characterization of a novel member of the Brassica S gene family, SFR2. RNA gel blot analysis demonstrated that SFR2 mRNA accumulated rapidly in response both to wounding and to infiltration with either of two bacteria: Xanthomonas campestris, a pathogen, and Escherichia coli, a saprophyte. SFR2 mRNA also accumulated rapidly after treatment with salicylic acid, a molecule that has been implicated in plant defense response signaling pathways. A SFR2 promoter and reporter gene fusion was introduced into tobacco and was shown to be induced by bacteria of another genus, Ralstonia (Pseudomonas) solanacearum. The accumulation of SFR2 mRNA in response to wounding and pathogen invasion is typical of a gene involved in the defense responses of the plant. The rapidity of SFR2 mRNA accumulation is consistent with SFR2 playing a role in the signal transduction pathway that leads to induction of plant defense proteins, such as pathogenesis-related proteins or enzymes of phenylpropanoid metabolism.
Base Sequence↗
A functional S locus anther gene is not required for the self-incompatibility response in Brassica oleracea.
The self-incompatibility (SI) response in Brassica involves recognition of self-pollen by the papillar cells of the stigma and is mediated by the products of genes localized at the S (self-incompatibility) locus. Two S locus genes, SRK and SLG, are thought to encode components of a receptor complex present in the female partner. The putative gene product of SLA, a third S locus-linked gene that is expressed specifically in anthers, is a candidate for the male component of the SI recognition system. The identification of a mutant SLA allele, interrupted by a large insert resembling a retrotransposon, in self-compatible Brassica napus initially suggested that SLA played an essential role in the SI response. In this study, we have characterized an SLA allele from a self-compatible B. oleracea var acephala line and show that it too is interrupted by a large insert. However, analysis of seven B. oleracea var botrytis lines exhibiting both self-compatible and self-incompatible phenotypes showed that these lines carry an S allele very similar or identical to that of the B. oleracea var acephala line and that the SLA gene is interrupted by an insert in all seven lines. The insertion of the putative retrotransposon was shown to interfere with gene expression, with no SLA transcripts being detected by RNA gel blot analysis in a self-incompatible B. oleracea var botrytis line carrying an interrupted SLA gene. These data indicate that a functional SLA gene is not required for the SI response in Brassica.
Amino Acid Sequence↗
Vigabatrin in partial seizures in children.
Patients with partial seizures aged 1 week to 19 years (n = 175) were included in several prospective vigabatrin studies at the hospital Saint Vincent de Paul. A decrease in seizure frequency of over 50% was achieved in 70% of patients, with 30% becoming seizure free, and only 6% experiencing an increase. Tuberous sclerosis gave the best response (85%), tumors the lowest (45%), the usual figure for other causes being 70%. Patients with malformations were the most likely to experience seizure increase. Regarding topography of focus, the lowest rate of seizure-free patients was in rolandic foci. Early treatment produced better results. Infants experienced the highest rate of response, but also of relapse, the latter occurring mainly between 6 months and 1 year. The incidence of loss of efficacy depended on etiology and topography of focus, tumors and frontal foci having the highest risk. Occurrence of new seizures was more frequent in young patients with tuberous sclerosis, the third experiencing status epilepticus. Vigabatrin monotherapy could only be achieved in 33% of seizure-free patients, reduction of comedication being a risk of relapse and of further intractability.
4-Aminobutyrate Transaminase↗
Optimizing the indication of vigabatrin in children with refractory epilepsy.
This review was conducted to evaluate the long-term prognosis of children responding to vigabatrin by examining the incidence of increased seizure frequency, loss of efficacy, and appearance of new seizures in a cohort of 196 children (mean age, 68.2 months; range, 2 months to 19 years) with drug-resistant epilepsy, who had received vigabatrin as add-on treatment in clinical trials. The results indicate that an increase in seizure frequency was uncommon, occurring in only 10% of children with highly drug-resistant epilepsy and that it usually appears shortly after the initiation of treatment. It was clearly not dose-dependent and most often occurred in patients with nonprogressive myoclonic epilepsy. No specific seizure type was specially involved and usually the problem reversed on discontinuing vigabatrin. Loss of efficacy was also uncommon (12% of patients), and again no specific seizure type was found to be associated. Epilepsy syndrome does seem to be a better predictor of loss of efficacy because it occurred most often in symptomatic generalized epilepsies and cryptogenic infantile spasms. A total of 21 patients (11%) developed genuinely new types of seizures. Fifteen of these patients developed new partial seizures that had little impact on the patients' overall clinical improvement. The new partial seizures were better tolerated than the initial seizure type which in most cases had disappeared. Approximately 3% of patients experienced new generalized seizures that aggravated their initial condition. These occurred most often in patients with nonprogressive myoclonic epilepsy; therefore vigabatrin should be used with particular caution in such patients.
Adolescent↗
First evidence of a calcium transient in flowering plants at fertilization.
We report here the first evidence of a transient elevation of free cytosolic Ca2+ following fusion of sperm and egg cell in a flowering plant by the use of an in vitro fertilization system recently developed in maize. Imaging changes in cytosolic Ca2+ at fertilization was undertaken by egg cell loading with the fluorescent Ca2+ indicator dye fluo-3 under controlled physiological conditions. The gamete adhesion step did not induce any cytosolic Ca2+ variation in the egg cell, whereas the fusion step triggered a transient cytosolic Ca2+ rise in the fertilized egg cell, lasting several minutes. This rise occurred after the establishment of gamete cytoplasm continuity. Through these observations, we open the way to the identification of the early signals induced by fertilization in flowering plants that give rise to the calcium transient and to investigations of the role of Ca2+ during egg activation and early zygote development in plants, as has been reported for other better characterized animal and algae systems.
Aniline Compounds↗
Crystallization of the RNA-binding domain of the transcriptional antiterminator protein SacY from Bacillus subtilis.
SacY is the antiterminator protein involved in the induction by sucrose of the expression of the levansucrase gene (sacB) of Bacillus subtilis. In the presence of sucrose, SacY is activated and prevents premature termination of transcription by binding to a RNA-antiterminator (RAT) sequence partially overlapping with the terminator sequence. SacY consists of a RNA-binding N-terminal domain, SacY(1-55), and a regulatory domain, SacY(56-280), sensitive to the sucrose concentration. SacY(1-55) is in itself capable of binding to the RAT sequence and preventing termination independently of the sucrose concentration. In this paper we describe the overexpression, the purification, and the crystallization of SacY(1-55). We obtained six different crystal forms, some of them diffracting to high resolution (> 1.5 A). Self rotation function calculations indicated the presence of a dimer in the asymmetric unit, which is in agreement with a proposed oligomeric state in solution as observed by high-resolution NMR measurements. The crystallization of some site-directed cysteine mutants opens the way of solving the structure by multiple isomorphous replacement.
Bacillus subtilis↗
Isolated maize zygotes mimic in vivo embryonic development and express microinjected genes when cultured in vitro.
We established conditions for the regeneration of natural maize zygotes isolated from pollinated plants with the goal of investigating the molecular control of early embryogenesis in higher plants. Viable zygotes were excised from embryo sacs by minimal enzymatic digestion and microdissection. Viable zygotes transferred to coculture with androgenic microspores from barley developed into embryo-like structures in 61% of the cases. No development was observed when zygotes were cultured in the presence of maize anthers undergoing androgenetic embryogenesis. Zygote-derived embryo-like structures regenerated into fertile plants through secondary embryogenesis when transferred to solid medium. The first zygotic division was asymmetrical and bipolar structures similar to pretransitional embryos observed in planta were later produced as observed using light and electron microscopy. Conditions for efficient microinjection of DNA into zygotes were established. Calcofluor and PATAG staining of zygotes showed that cell wall regeneration occurred as early as 20 min after enzymatic isolation and that after 2 hr, each zygote was bordered with cell wall material. Through quantitative microphotometry, DNA synthesis during the first cell cycle of the zygote was shown to occur between isolation and 12 hr of culture. Microinjection of two types of reporter genes (GUS gene and anthocyanin regulatory genes) demonstrates transient expression in plant zygotes. On average, 3.5% of microinjected zygotes showed transgenic expression. Reporter gene expression was observed in zygotes at different time points of their first cell cycle.
Cell Cycle↗
Cryopexy in primary rhegmatogenous retinal detachment: a risk factor for postoperative proliferative vitreoretinopathy?
PURPOSE: To evaluate the role of cryopexy in the stimulation of postoperative proliferative vitreoretinopathy (PVR) in primary rhegmatogenous retinal detachment. MATERIALS AND METHODS: A series of 595 eyes of 554 patients with primary rhegmatogenous retinal detachment, referred before any failed surgery, were prospectively evaluated. Univariate and multivariate statistical analyses of the data were conducted. RESULTS: The incidence of postoperative PVR in relation to the methods used for retinopexy was dependent on the types and anatomy of retinal breaks associated with retinal detachment. The incidence of postoperative PVR was nil in retinal detachments due to atrophic holes in lattice, oral dialyses, and macular holes, regardless of the retinopexy methods. Postoperative PVR occurred solely in retinal detachments due to horseshoe tears (incidence 4.42%), paravascular tears of the postequatorial region (18.18%), and giant tears (24.6%) (P < 0.00001). The incidence of postoperative PVR was 0.5% in eyes with horseshoe tears with mobile posterior edges vs 9.72% in eyes with horseshoe tears with curled posterior edges, regardless of the retinopexy methods (P < 0.00001). In retinal detachments due to horseshoe tears with mobile posterior edges the incidence of postoperative PVR (0.5%) was not influenced by the retinopexy methods. In contrast, in retinal detachments due to horseshoe tears with curled posterior edges the incidence of postoperative PVR was higher in eyes managed with cryopexy (14.77%) than in eyes managed with laser retinopexy (1.78%) (P < 0.02). In retinal detachments due to giant tears the incidence of postoperative PVR was not statistically significantly greater in eyes managed with cryopexy (33.3%) than in eyes managed with laser retinopexy (15.6%). In tears 180 degrees and over in size, however, the incidence of postoperative PVR was significantly higher in eyes managed with cryopexy (9/11 eyes) than in eyes managed with laser retinopexy (5/17 eyes) (P = 0.006). CONCLUSIONS: Cryopexy is not a stimulating factor for postoperative PVR in primary rhegmatogenous retinal detachments due to atrophic holes in lattice, oral dialyses, macular holes, or horseshoe tears with mobile posterior edges. In contrast, cryopexy probably is a stimulating factor for postoperative PVR in retinal detachments due to horseshoe tears with curled posterior edges or to retinal tears 180 degrees and over.
Adolescent↗
Effects of destruxins, cyclic depsipeptide mycotoxins, on calcium balance and phosphorylation of intracellular proteins in lepidopteran cell lines.
The influence of the destruxin E, cyclodepsipeptidic mycotoxin produced by the filamentous entomopathogenic fungus Metarhizium anisopliae, on calcium fluxes and protein phosphorylation of in vitro cultivated lepidopteran cell lines have been studied. The use of the fluorescent calcium indicator Fura 2 AM did not show a fast increase in the level of cytosolic calcium in lepidopteran and human cell lines treated with dtx E. In contrast, 45Ca+2 assays detected a late but significant calcium influx in insect cells exposed to dtx E and A for at least 30 min. This effect was not inhibited by calcium channel blockers with the exception of nifedipine 25 microM. A viral treatment potentiated the effect of dtx E on calcium balance. Dtx E also induced a strong, fast (10 min), transient phosphorylation of high molecular weight (250 kDa) cellular proteins. The activation of phosphorylation was only partially inhibited by EDTA. This study provides the first direct evidence of dtx E influence on calcium fluxes and protein phosphorylation.
Animals↗
Pharmacokinetics of the individual enantiomers of vigabatrin in neonates with uncontrolled seizures.
The antiepileptic drug vigabatrin (VGB) is a selective irreversible inhibitor of GABA-transaminase. It is administered as a racemic R(-), S(+) mixture, but the pharmacological activity of vigabatrin resides in the S(+) enantiomer and the R(-) enantiomer is inactive. The pharmacokinetic parameters of the two enantiomers have been studied after administration of a single oral 125 mg dose of the racemate to six neonates. The mean values of Cmax and AUC of the S(+) enantiomer were significantly lower (Cmax: 14.0 +/- 4.3 mg l-1; AUC: 143 +/- 44 mg l-1 h) than those of the R(-) enantiomer (Cmax: 34.1 +/- 9.5 mg l-1; AUC: 231 +/- 88 mg l-1 h), whereas no significant difference in the time to reach Cmax (S(+): 2.1 +/- 1.1 h; R(-): 2.2 +/- 1 h) was observed between the two enantiomers. During chronic administration (125 mg twice daily over 4 days), there was no evidence of accumulation of either enantiomer.
Anticonvulsants↗
Structural and functional properties of mutant Arg203Pro from yeast phosphoglycerate kinase, as a model of phosphoglycerate kinase-Uppsala.
A pathological variant of human phosphoglycerate kinase, phosphoglycerate kinase-Uppsala, associated with chronic nonspherocytic hemolytic anemia has been found to differ from the normal enzyme by substitution of an arginine at position 206 (corresponding to position 203 in yeast) by a proline. In order to understand the structural and functional consequences of this mutation, the corresponding mutant in yeast phosphoglycerate kinase was constructed. The three-dimensional structure of this mutant was resolved at 2.9 A. Although the overall structure is not modified, small local changes were observed. The kinetic parameters of the mutant were not found to be greatly affected, the catalytic constant being lowered by only 10-20%. The most significant difference when compared with the wild-type enzyme is a decrease in stability by about 3 kcal/mol. The physiological implications of this instability are discussed.
Circular Dichroism↗