[Etiopathogenesis of nasal obstruction in children].
The author lists the dysmorphic and dysfunctional causes of nasal obstruction in the child.
Child↗
Biomedical subjects
O Richard
Publications and source records attributed to O Richard.
[Complications of nasal obstruction in children].
The author reviews the morphogenetic and functional consequences of oral breathing in childhood.
Cephalometry↗
[Functional and esthetic rhinoplasty in orthognathic surgery].
The author presents a surgical rhinoplasty, aiming at functional and aesthetic purposes, in dentofacial orthopedics.
Esthetics↗
Room-temperature and low-temperature structure of Nd1-xCaxMnO3 (0.3 </= x </= 0.5).
The structure of the insulating manganites Nd(1-x)Ca(x)MnO(3) (0.3 </= x </= 0.5) has been studied against temperature using electron diffraction and neutron diffraction. At room temperature, the three compounds with x = 0.3, 0.4 and 0.5 exhibit the orthorhombic GdFeO(3)-type structure (a approximately 2(1/2)a(p), b approximately 2a(p), c approximately 2(1/2)a(p)). Below the charge-ordering temperature of approximately 250 K, a doubling of the lattice is observed along the a axis which could be interpreted as an ordering of the d(z(2)) Mn(3+) orbitals. The low-temperature polymorph has ortho-rhombic symmetry for x = 0.5 and monoclinic symmetry for x = 0.4 and 0.3. The low-temperature structure of the x = 0.4 sample was refined using neutron diffraction data. The HREM study at room temperature confirms the average GdFeO(3)-type structure and indicates the existence of defective areas with a lower symmetry.
Journal Article↗
mRNA expression in mitochondria of the red alga chondrus crispus requires a unique RNA-processing mechanism, internal cleavage of upstream tRNAs at pyrimidine 48.
The hypothesis that tRNAs are involved in the maturation of the large primary transcripts of Chondrus crispus mitochondrial DNA was addressed by primer extension mapping of the transcript 5' ends of the ten genes that are preceded by tRNA genes in C. crispus mitochondrial genome. Among the 12 tRNAs that were candidates as maturation signals, eight, namely tRNAArg, tRNALys, tRNAAsp, tRNAGln, tRNATrp, tRNAIle, tRNAPhe and tRNAGly, were cleaved internally upon maturation of C. crispus mitochondrial primary transcripts, all of them at the same base, invariant pyrimidine 48. Only four tRNAs departed from this pattern: tRNALeu and tRNACys, which are not maturation signals, tRNAMet, which appears to be excised as a whole from the orf94 primary trancript and tRNAAla, which is cleaved internally at positions other than Y48. Sequence comparisons between the cleaved and the uncleaved tRNAs suggest that their core tertiary structure is involved with their recognition and cleavage. However, the precursor transcripts are also processed at the 5' and 3' ends of the tRNAs to yield tRNA molecules that are stable and functional in translation. This indicates that two different RNA processing mechanisms coexist in C. crispus mitochondria, one required for the production of functional tRNAs and the other for the processing of mRNAs.
Base Sequence↗
The transport of the histidine-rich protein I from Plasmodium falciparum is insensitive to brefeldin A.
During its intraerythrocytic development, Plasmodium falciparum synthesizes several proteins that are exported beyond its membrane. Some of these secreted antigens are involved in the formation of protuberances or knobs, a major virulence factor, at the erythrocyte membrane. Various secreted malarial polypeptides, the transport of which is sensitive to brefeldin A, are translocated in vitro into dog pancreatic microsomes. We present evidence that the histidine-rich protein I (PfHRPI) is secreted by the parasite via a novel pathway, independent of the ER/Golgi apparatus. The secretion of PfHRPI was not blocked by incubation of parasite cultures at 15 degrees C and 20 degrees C or 37 degrees C in the presence of brefeldin A. PfHRPI was not translocated into microsomes in an in vitro translation-translocation cell-free system. Unlike other polypeptides from eukaryotic cells that bypass the ER/Golgi pathway and do not have a signal peptide, PfHRPI has an atypical signal sequence consisting of 21 amino acids, including eight positively charged residues followed by 11 hydrophobic residues. We also found that the unusually charged PfHRPI signal sequence diverts Exp-1, which is usually exported, away from the translocation machinery of microsomal membranes.
Animals↗
Thrombocytopenia in a surgical ICU.
STUDY OBJECTIVES: To assess the incidence of thrombocytopenia in surgical ICU patients, the factors associated with thrombocytopenia, the outcome of thrombocytopenic patients, and the possible mechanisms involved. DESIGN: Prospective study. SETTING: An 8-bed surgical ICU in an 885-bed teaching hospital. PATIENTS: 147 consecutive patients admitted to the surgical ICU during a 6-month period. MAIN OUTCOME MEASURES: Incidence of thrombocytopenia (defined by a platelet count < 100,000/mm3), risk factors for thrombocytopenia, or death in thrombocytopenic patients identified by a stepwise logistic regression analysis, as well as the mechanisms involved. RESULTS: Thrombocytopenia occurred in 52 patients (35%) with a mortality rate of 38%, compared with a 20% mortality rate in nonthrombocytopenic patients (p = 0.02). Sepsis, episodes of bleeding or transfusions, and an acute physiology and chronic health evaluation (APACHE) II score of > 15 were the independent risk factors identified for thrombocytopenia. The correction of thrombocytopenia was a protective factor reducing the risk of mortality in thrombocytopenic patients. Disseminated intravascular coagulation was found in 40% of thrombocytopenic patients, elevated platelet-associated IgG in 33%, and hemophagocytic histiocytes in 67%. Combinations of two of these mechanisms were demonstrated in one quarter of thrombocytopenic patients. CONCLUSIONS: Sepsis was the major independent risk factor identified. Thrombocytopenic patients had a higher ICU mortality due to the severity of overall clinical status. Bone marrow examination could be diagnostic when no obvious causes are demonstrated. Thrombocytopenia probably reflects the severity and course of an underlying pathologic condition, as its correction appears to be a good prognostic factor.
APACHE↗
Transcription initiation and RNA processing in the mitochondria of the red alga Chondrus crispus: convergence in the evolution of transcription mechanisms in mitochondria.
The mitochondrial DNA (mt DNA) of the red alga Chondrus crispus is shown to be transcribed into two large RNA molecules. These primary transcripts are cleaved once, at the level of a tRNA, then the resulting products are processed via multiple maturation events into either mono- or poly-cistronic RNAs. Transcripts were detected for all genes and open reading frames, except for rps11 and orf172. For both transcription units the initiation of transcription was mapped by in vitro RNA capping and primer extension experiments within inverse repeated sequences at the north pole of the molecule. Consistent with primer extension mapping, putative promoter motifs sharing significant similarities with both chicken and Xenopus mitochondrial promoters were found in the C. crispus mitochondrial genome. Altogether C. crispus mitochondrial DNA appears to be transcribed as animal mtDNA is, suggesting that transcription mechanisms in mitochondria are dependent on the overall organization of the mitochondrial genome irrespective of the eukaryotic phylogeny.
Animals↗
Early, middle, and late stages of neural cells from ovine embryo in primary cultures.
The utilization of neural cells in culture has importantly increased the knowledge of the nervous system biology. In most studies, the investigations are performed on biological materials coming from common laboratory animals and the extrapolation of the results to other animals is not easy. For some studies, such as developmental biology of the nervous system, prion disease investigations, or agronomical production, the utilization of ovine neural cell cultures presents many advantages. Unfortunately, there are few data on the conditions of culture of such cells. In the present work, we investigated simple ways to obtain neurons and astrocytes from sheep brain. Viable neuronal cell cultures were obtained from 40 to 50 day old fetuses. Their morphologies were quite similar to that of neurons from rodent or chick brain and they were labeled by antineurofilament antibodies. Stages older than 50 days of pregnancy were unable to give viable culture of neurons. The stages of 40 day old fetus to newborn lamb were able to give viable astrocyte cultures. The common protoplasmic astrocytes were obtained and they were labeled by antiglial fibrillary acidic protein antibodies. The astrocytes contained glycogen, thus looking like the common astrocytes from rodents. Neuronal or astroglial cultures can be derived from 26 day old embryos, but the cultures contained contaminating cells. Among the latter cells, there were undifferentiated cells which were flat and epitheloid and which were grouped as islets. These cells could be maintained in culture for a time duration over 7 months, even after two passages. They differentiated principally in astrocytes with a radial configuration. This work shows how some neural cells can be simply and easily cultured from sheep brain. For the first time, neurons were cultured from the sheep embryonic brain. Moreover, stem cells were cultured for more than 7 months and, finally, glycogen accumulation in sheep astrocytes was shown to be the same as that in rodent astrocytes. The oligodendrocyte culture was already documented. Thus, sheep can easily be used as well as other models for neural cell studies.
Animals↗
Isolated aldosterone synthase deficiency caused by simultaneous E198D and V386A mutations in the CYP11B2 gene.
Isolated deficiencies in aldosterone biosynthesis are caused by mutations in the CYP11B2 (aldosterone synthase) gene. Patients with this deficiency have impaired aldosterone synthesis, exhibit increased plasma renin activity, secrete increased amounts of the steroid precursors DOC, corticosterone, and 18OHDOC, and are subject to salt wasting and poor growth. Two forms are generally distinguished. The first, corticosterone methyloxidase type I (CMO I or type 1 deficiency), is characterized by no detectable aldosterone secretion, a low or normal secretion of the steroid 18OHB, and are always found to have mutations that completely inactivate the encoded CYP11B2 enzyme. The second form (CMO II or type 2 deficiency) may have low to normal levels of aldosterone, but at the expense of greatly increased secretion of its immediate precursor 18OHB. These patients usually have a CYP11B2 enzyme with some residual enzymatic activity, especially 11beta-hydroxylase activity. We have studied two twins with an isolated aldosterone synthase activity who have a clinical profile typical of the type 1 deficiency. Their CYP11B2 genes are homozygous for three sequence changes, R173K, E198D, and V386A. In transfection assays these substitutions individually have modest effects on the encoded enzyme, but when found together they result in an enzyme with a decreased 11beta-hydroxylase activity, a large decrease of 18-hydroxylase activity, and no detectable 18-oxidase activity. This residual activity is more typical of that observed in patients classified as having CMO II deficiency, rather than CMO I deficiency, where no activity is detectable. This disparity between the CYP11B2 enzyme with residual activity and a clinical phenotypic typical of the type 1 deficiency, suggests that phenotype genotype relationships are not yet fully understood.
Cytochrome P-450 CYP11B2↗
Origin and evolution of mitochondria: what have we learnt from red algae?
The purpose of this review is to present an account of our current understanding of the structure, organization and evolution of mitochondrial genomes, and to discuss the origin and evolution of mitochondria from the perspective recently provided by the extensive sequencing of various mitochondrial genomes. Mitochondrial-en-coded protein phylogenies are congruent with nuclear phylogenies and strongly support a monophyletic origin of mitochondria. The newly available data from red-algal mitochondrial genomes, in particular, show that the structural and functional diversity of mitochondrial genomes can be accounted for by paralogous evolution. We also discuss the influence of other constraints, such as uniparental inheritance, on the evolution of genome organization in mitochondria.
DNA, Circular↗
[A familial case with generalized resistance to thyroid hormones].
BACKGROUND: The syndrome of generalized resistance to thyroid hormones is more frequent than was thought. CASE REPORTS: A 13-year old girl was examined for her short stature. Evaluation of her thyroid function showed increased levels of IT3 and IT4 and normal value of TSH; she also had mosaic Turner's syndrome. Her cousin was rapidly diagnosed as suffering from the same syndrome because of moderately high thyrotropic levels found during neonatal screening; this syndrome was confirmed by molecular biology tests. Five generations of this family were identified as being affected with a pattern indicating autosomal dominant inheritance. CONCLUSION: The clinical manifestations of familial generalized resistance to thyroid hormones vary but this syndrome is easy to biologically confirm. The importance of diagnosing affected children as early as possible should be emphasized, as in such cases their development must be closely monitored particularly where their growth and neurodevelopment are concerned.
Adolescent↗
[Cystic compression of the suprascapular nerve. Value of imaging. Apropos of 6 cases and review of the literature].
Six cases of suprascapular nerve entrapment by a ganglion cyst within the spinoglenoid notch or developed from the glenoid labrum are reported. Causes of injury or entrapment of the suprascapular nerve are described including traction or kinking of the nerve, trauma, repetitive exercise, or compression by ganglion cyst. The patients had non specific pain, weakness, and atrophy of the spinatus musculature. Electromyography showed evidence of denervation atrophy. Patients had plain radiographs, arthrography, CT-arthrography, magnetic resonance imaging (MRI) and MR-arthrography. Masses that caused suprascapular nerve entrapment were well localized and characterized wit magnetic resonance imaging, reflecting the superior soft-tissue contrast of this modality. In addition, MRI may demonstrate atrophy of the spinatus muscles. MR-arthrography allows to visualize lesions of the glenoid labrum and in some cases, demonstrates cysts filling.
Adult↗
The Seismic Structure of the Sun
Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics.
Journal Article↗
Genes for two subunits of succinate dehydrogenase form a cluster on the mitochondrial genome of Rhodophyta.
Mitochondrial DNA from the unicellular rhodophyte Cyanidium caldarium RK-1 and the multicellular Chondrus crispus were isolated, cloned, and sequenced. Two genes, sdhB and sdhC, that encode subunits of the succinate dehydrogenase, were identified by similarity. These genes form a cluster (sdhCB) in both red algae.
Amino Acid Sequence↗
Methionine sulfoximine increases acetylcholine level in the rat brain: no relation with epileptogenesis.
Methionine sulfoximine induces epileptiform convulsions in rats. A possible involvement of acetylcholine in the onset of convulsions was investigated. A subconvulsive dose of methionine sulfoximine increased the brain acetylcholine concentration. After administration of a convulsive dose, atropine neither prevented the onset of the seizures nor prevented the increase in acetylcholine concentration. Physostigmine enhanced the increase in acetylcholine level but did not modify the time course nor the intensity of the convulsions. L-DOPA suppressed the seizures without inhibiting the increase in acetylcholine level. The choline content decreased after the convulsant dose. The increase in acetylcholine content is therefore not the unique cause of the seizures, which could result from the reduction of striatal inhibition due to a decrease in dopamine level induced by methionine sulfoximine.
Acetylcholine↗
Complete sequence of the mitochondrial DNA of the rhodophyte Chondrus crispus (Gigartinales). Gene content and genome organization.
The complete nucleotide sequence of the circular mitochondrial (mt) DNA from the red alga Chondrus crispus was determined (25,836 nucleotides, A+T content 72.1%). Fifty one genes were identified. They include genes encoding three subunits of the cytochrome oxidase (cox1 to 3), apocytochrome b (cob), seven subunits of the NADH dehydrogenase complex (nad1 to 6, nad4L), two ATPase subunits (atp6 and atp9), three ribosomal RNAs (rrn5, srn and lrn), 23 tRNAs and four ribosomal proteins (rps3, rps11, rps12 and rpl16). Two subunits of the succinate dehydrogenase complex (sdhB and sdhC), usually found on nuclear genomes, are also located on the mtDNA of C. crispus. One group IIb intron is inserted in the tRNAIle gene. Six potentially functional open reading frames were identified, four of them having counterparts among green plant mtDNAs. The use of a modified genetic code and the absence of RNA editing, previously reported for the cox3 gene, appears as a general characteristic of this molecule. Mitochondrial genes are encoded on both DNA strands, in two opposite major transcriptional directions, suggesting the existence of two main transcriptional units. Two long and stable stem-loops were identified in intergenic regions, which are believed to be involved with transcription and replication. The main structural features of this genome are compared with the overall organization of mtDNAs and are discussed in view of the evolution of mitochondria.
Amino Acid Sequence↗
Fulminant liver failure in a 12-year-old girl with sickle cell anaemia: favourable outcome after exchange transfusions.
UNLABELLED: Acute liver failure is unusual in sickle cell anaemia. We describe a child with homozygous sickle cell anaemia who developed acute liver disease of abrupt onset during an episode of limb pain. She presented with sudden onset of persistent vomiting, headache, lethargy, epistaxis, and painful liver enlargement. Laboratory investigations were indicative of cholestasis and severe liver failure with profound prolonged clotting times, hypofibrinogenaemia, elevated serum ammonia and lactic acidosis. The symptoms were promptly and completely reversed by two partial exchange transfusions. No evidence of viral infection was found. Cholelithiasis was ruled out by ultrasonography. The child recovered from what appeared to be massive hepatic sickling with no apparent sequelae. CONCLUSION: Massive hepatic sickling should be considered in the differential diagnosis of a child with homozygous sickle cell disease who suddenly develops acute liver failure. Exchange transfusion should be promptly carried out so as to reverse ischaemic hepatic injury.
Acute Disease↗