Bilateral osteochondrosis of the distal tibial epiphysis: a case report.

Osteochondrosis is a developmental disease characterized by an alteration of endochondral ossification. Genetic causes, repetitive mechanical stresses, vascular abnormalities, hormonal imbalances, and interruption of the blood supply to the epiphyseal cartilage are all described causes of osteochondrosis and the etiology is probably multifactorial. Osteochondrosis can occur in different apophysis and epiphysis in all immature skeletons. Distal tibial epiphysis is rarely involved and most of the time unilaterally. We report on an 11-year-old female with bilateral osteochondrosis on distal tibial epiphysis. Only one other similar case has been described in the literature to date.

A miR169 isoform regulates specific NF-YA targets and root architecture in Arabidopsis.

In plants, roots are essential for water and nutrient acquisition. MicroRNAs (miRNAs) regulate their target mRNAs by transcript cleavage and/or inhibition of protein translation and are known as major post-transcriptional regulators of various developmental pathways and stress responses. In Arabidopsis thaliana, four isoforms of miR169 are encoded by 14 different genes and target diverse mRNAs, encoding subunits A of the NF-Y transcription factor complex. These miRNA isoforms and their targets have previously been linked to nutrient signalling in plants. By using mimicry constructs against different isoforms of miR169 and miR-resistant versions of NF-YA genes we analysed the role of specific miR169 isoforms in root growth and branching. We identified a regulatory node involving the particular miR169defg isoform and NF-YA2 and NF-YA10 genes that acts in the control of primary root growth. The specific expression of MIM169defg constructs altered specific cell type numbers and dimensions in the root meristem. Preventing miR169defg-regulation of NF-YA2 indirectly affected laterial root initiation. We also showed that the miR169defg isoform affects NF-YA2 transcripts both at mRNA stability and translation levels. We propose that a specific miR169 isoform and the NF-YA2 target control root architecture in Arabidopsis.

Aplasia cutis congenita: review of 29 cases and proposal of a therapeutic strategy.

INTRODUCTION: Aplasia cutis congenita (ACC) is a rare congenital disorder, which most commonly involves the scalp, and can affect the galea, the pericranium, the bone, and the dura mater. ACC thus is at risk of infection and hemorrhage. There is no consensus over the ideal management and the role for plastic surgery. MATERIALS AND METHODS: We reviewed retrospectively our experience with 29 patients treated between 1976 and 2011. RESULTS: The patients were 17 male and 12 female, 25 being referred immediately at birth. The size of the defect ranged from 1 to 192 cm2. Thirteen patients had bone aplasia. Initial conservative treatment was decided in five cases; 15 patients underwent excision-sutures with or without local plasty, 8 underwent pedicled scalp flap, and 1 had skin graft followed by further reconstruction by a free flap. Four patients died in neonatal period because of infection or associated ailments. All others patients achieved complete healing. DISCUSSION: The mortality rate of ACC remains high and increases with the size of bone defect. We propose a therapeutic strategy based on the size of the skin defect and the nature of underlying exposed structures. Cranioplasty is exceptionally necessary because of good spontaneous bone regeneration within few months or years. Cosmetic appearance can be improved later by skin expansion. CONCLUSION: Aplasia cutis congenita is a rare malformation with sometimes a rapid fatal issue. A precise evaluation of surface and depth of the lesion is essential to decide if and how to operate, in order to provide rapid and efficient coverage.

Long-term results in scalp tissue expansion in children.

INTRODUCTION: Tissue expansion is frequently used in scalp repair in children. The short-term complications are well known and described in the literature. Impacts at a distance such as potential deformation of the skull or widening of the scar are not so often presented. The aim of this study is to analyze the results at a distance and the actual impact after scalp tissue expansion in young children. MATERIALS AND METHODS: We clinically reviewed 15 children operated on between May 2002 and April 2008 for scalp tissue expansion.Results Mean follow-up was 3 years and 5 months, and mean age of the patients at the first surgery was 20 months. In 11 cases, we observed a widening of the scar. Only two patients presented with a slight flattening of the skull. All parents were satisfied with the results. Children do not remind or keep no unpleasant memory of the surgical protocol. DISCUSSION: Only rare studies focused on very young children. Most of surgeons fear about the consequences of scalp tissue expansion on cranial bone and thus on cerebral growth in children under the age of 2. But it appears that cranial changes in young children are transient with a return to normal within 6 months after removing the implant. Another common problem is the scar enlargement. According to our results and the review of the literature, it seems essential to perform the suture in two layers associated to local reconstruction on the scar to provide the best cosmetic outcomes. CONCLUSION: Tissue expansion remains a good technique to repair large lesions of the scalp in children. The deformation of the skull spontaneously resolves and does not have any consequence on brain growth. The widening of the scar is a common problem in children but can be reduced by suture in two layers associated with local reconstruction. Moreover, young children do not keep any unpleasant memory of this period and are not susceptible to social pressure.

MicroRNAs as regulators of root development and architecture.

MicroRNAs (miRNAs) are post-transcriptional regulators of growth and development in both plants and animals. In plants, roots play essential roles in their anchorage to the soil as well as in nutrient and water uptake. In this review, we present recent advances made in the identification of miRNAs involved in embryonic root development, radial patterning, vascular tissue differentiation and formation of lateral organs (i.e., lateral and adventitious roots and symbiotic nitrogen-fixing nodules in legumes). Certain mi/siRNAs target members of the Auxin Response Factors family involved in auxin homeostasis and signalling and participate in complex regulatory loops at several crucial stages of root development. Other miRNAs target and restrict the action of various transcription factors that control root-related processes in several species. Finally, because abiotic stresses, which include nutrient or water deficiencies, generally modulate root growth and branching, we summarise the action of certain miRNAs in response to these stresses that may be involved in the adaptation of the root system architecture to the soil environment.

A novel fry1 allele reveals the existence of a mutant phenotype unrelated to 5'->3' exoribonuclease (XRN) activities in Arabidopsis thaliana roots.

BACKGROUND: Mutations in the FRY1/SAL1 Arabidopsis locus are highly pleiotropic, affecting drought tolerance, leaf shape and root growth. FRY1 encodes a nucleotide phosphatase that in vitro has inositol polyphosphate 1-phosphatase and 3',(2'),5'-bisphosphate nucleotide phosphatase activities. It is not clear which activity mediates each of the diverse biological functions of FRY1 in planta. PRINCIPAL FINDINGS: A fry1 mutant was identified in a genetic screen for Arabidopsis mutants deregulated in the expression of Pi High affinity Transporter 1;4 (PHT1;4). Histological analysis revealed that, in roots, FRY1 expression was restricted to the stele and meristems. The fry1 mutant displayed an altered root architecture phenotype and an increased drought tolerance. All of the phenotypes analyzed were complemented with the AHL gene encoding a protein that converts 3'-polyadenosine 5'-phosphate (PAP) into AMP and Pi. PAP is known to inhibit exoribonucleases (XRN) in vitro. Accordingly, an xrn triple mutant with mutations in all three XRNs shared the fry1 drought tolerance and root architecture phenotypes. Interestingly these two traits were also complemented by grafting, revealing that drought tolerance was primarily conferred by the rosette and that the root architecture can be complemented by long-distance regulation derived from leaves. By contrast, PHT1 expression was not altered in xrn mutants or in grafting experiments. Thus, PHT1 up-regulation probably resulted from a local depletion of Pi in the fry1 stele. This hypothesis is supported by the identification of other genes modulated by Pi deficiency in the stele, which are found induced in a fry1 background. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the 3',(2'),5'-bisphosphate nucleotide phosphatase activity of FRY1 is involved in long-distance as well as local regulatory activities in roots. The local up-regulation of PHT1 genes transcription in roots likely results from local depletion of Pi and is independent of the XRNs.

Small RNA diversity in plants and its impact in development.

MicroRNAs are a class of non-coding RNAs involved in post-transcriptional control of gene expression, either via degradation or translational inhibition of target mRNAs. Both experimental and computational approaches have been used to identify miRNAs and their target genes. In plants, deep sequencing methods have recently allowed the analysis of small RNA diversity in different species and/or mutants. Most sequencing efforts have been concentrated on the identification of miRNAs and their mRNA targets have been predicted based on complementarity criteria. The recent demonstration that certain plant miRNAs could act partly via inhibition of protein translation certainly opens new fields of analysis for plant miRNA function on a broader group of targets. The roles of conserved miRNAs on target mRNA stability have been analysed in different species and defined common mechanisms in development and stress responses. In contrast, much less is known about expression patterns or functions of non-conserved miRNAs. In this review, we focus on the comparative analyses of plant small RNA diversity and the action of si/miRNAs in post-transcriptional regulation of some key genes involved in root development.