Exhaustive scanning approach to screen all the mitochondrial tRNA genes for mutations and its application to the investigation of 35 independent patients with mitochondrial disorders

To gain a better understanding of the molecular basisof mitochondrial (mt) encephalomyopathies, a highly heterogeneous condition, we developed a denaturing gradient gel electrophoresis-based approach that allows rapid and exhaustive screening for mutations of all 22 mt tRNA-encoding genes and their flanking regions in large cohorts of patients. This method, that detects heteroplasmy (i.e. co-existence of mutant and wild-type mtDNA species in various ratios) directly, was applied to the investigation of 35 independent patients with a disease phenotype compatible with a mitochondrial encephalomyopathy. Twenty-five of the 35 patients investigated displayed a sequence variation in at least one tRNA gene. A total of 46 different sequence variations (41 point mutations, four short insertions and one short deletion), among which 20 are new, were characterized. Forty of them were present in a homoplasmic state, whereas six were heteroplasmic. Twenty-two were located in tRNA genes, among which 10 are new homoplasmic or heteroplasmic sequence variations; 24 were located in flanking regions (12 in mRNA-encoding genes, seven of them leading to missense sequence variations; two in rRNA genes; and 10 in non-coding regions). This study demonstrates (i) the high frequency of homoplasmic tRNA gene sequence variations in our patient sample, and (ii) the existence of several polymorphic sites in tRNA gene regions that may be helpful for defining haplogroups in different populations. It relies on a screening method that can now be applied easily to other population samples.

[The incidence of prescriptions without marketing product license in a neonatal intensive care unit]

Most of the drugs prescribed in pediatric units have no product licence. The lack of clinical studies in children and appropriate drug formulations decrease their safety. The lack of a legal framework makes the prescriber insecure. Even if the debate is not recent, few studies have been carried out in this field. The aim of the present study was to evaluate the rate of prescriptions of unlicensed and off-label drugs in a neonatal intensive care unit.

PATIENTS AND METHODS

The present study was carried out in our neonatal intensive care unit, from January 12 to February 12, 1998. Forty babies aged 0 to 128 days were included (90% newborns), with a gestational age between 25 to 40 weeks (88% were premature, with a birth weight lower than 1000 g).

RESULTS

Two hundred and fifty-seven prescriptions were administered with 55 different types of drugs during this period. Ten percent of the prescribed drugs had no product licence. Sixty-two percent were off-label for premature infants and 64% for newborns: 90% due to age, 9.3% due to dose and 0.7% to method of administration. No therapeutic alternatives to these prescriptions were found among the few available licensed drugs.

CONCLUSION

The prescriptions of unlicensed and off-label drugs in neonatal intensive care units are daily and repeated events. The prescribers are usually not aware of the exact status of the drug and do not realize neither he importance of the problem nor the legal and potential consequences. The lack of pediatric clinical studies is to a large extent responsible for the absence of drug registration in pediatrics. The pharmaceutical industry has few incentives to develop the pediatric product licences.

Evaluation of parental mitochondrial inheritance in neonates born after intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) is now used when severe male-factor infertility has been documented. Since defective mitochondrial functions may result in male hypofertility, it is of prime importance to evaluate the risk of paternal transmission of an mtDNA defect to neonates. DNA samples from the blood of 21 infertile couples and their 27 neonates born after ICSI were studied. The highly polymorphic mtDNA D-loop region was analyzed by four PCR-based approaches. With denaturing gradient gel electrophoresis (DGGE), which allows 2% of a minor mtDNA species to be detected, the 27 newborns had a DGGE pattern identical to that of their mother but different from that of their father. Heteroplasmy documented in several parents and children supported an exclusive maternal inheritance of mtDNA. The parental origin of the children's mtDNA molecules also was studied by more-sensitive assays: restriction-endonuclease analysis (REA) of alpha[32P]-radiolabeled PCR products; paternal-specific PCR assay; and depletion of maternal mtDNA, followed by REA. We did not detect paternal mtDNA in nine neonates, with a sensitivity level of 0.01% in five children, 0.1% in two children, and 1% in two children. The estimated ratio of sperm-to-oocyte mtDNA molecules in humans is 0.1%-1.5%. Thus, we conclude that, in these families, the ICSI procedure performed with mature spermatozoa did not alter the uniparental pattern of inheritance of mtDNA.

Nationwide outbreak of Salmonella enterica serotype 4,12:i:- infections in France, linked to dried pork sausage, March-May 2010

In May 2010, a nationwide excess of infections with the specific monophasic variant Salmonella enterica serotype 4,12:i:- was investigated in France. Subtyping with multilocus variable number of tandem repeats analysis revealed a distinct epidemic strain within this excess. Epidemiological investigations identified a dried pork sausage sold by a particular chain of supermarkets as the likely vehicle of transmission. The suspected batches have been withdrawn and recalled.

PAR-CLIP: A Method for Transcriptome-Wide Identification of RNA Binding Protein Interaction Sites

During post-transcriptional gene regulation (PTGR), RNA binding proteins (RBPs) interact with all classes of RNA to control RNA maturation, stability, transport, and translation. Here, we describe Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP), a transcriptome-scale method for identifying RBP binding sites on target RNAs with nucleotide-level resolution. This method is readily applicable to any protein directly contacting RNA, including RBPs that are predicted to bind in a sequence- or structure-dependent manner at discrete RNA recognition elements (RREs), and those that are thought to bind transiently, such as RNA polymerases or helicases.

Continuous tracheal gas insufflation enables a volume reduction strategy in hyaline membrane disease: technical aspects and clinical results

OBJECTIVE

Instrumental dead space wash-out can be used to improve carbon dioxide clearance. The aim of this study was to define, using a bench test, an optimal protocol for long-term use, and to assess the efficacy of this technique in neonates.

DESIGN

A bench test with an artificial lung model, and an observational prospective study. Dead space wash-out was performed by continuous tracheal gas insufflation (CTGI), via six capillaries molded in the wall of a specially designed endotracheal tube, in 30 preterm neonates with hyaline membrane disease.

SETTING

Neonatal intensive care unit of a regional hospital.

RESULTS

The bench test study showed that a CTGI flow of 0.5 l/ min had the optimal efficacy-to-side-effect ratio, resulting in a maximal or submaximal efficacy (93 to 100%) without a marked increase in tracheal and CTGI circuit pressures. In the 30 newborns, 15 min of CTGI induced a significant fall in arterial carbon dioxide tension (PaCO2), from 45 +/- 7 to 35 +/- 5 mmHg (p = 0.0001), and in 14 patients allowed a reduction in the gradient between Peack inspirating pressure and positive end-expiratory pressure from 20.8 +/- 4.6 to 14.4 +/- 3.7 cmH2O (p < 0.0001) while keeping the transcutaneous partial pressure of carbon dioxide constant. As predicted by the bench test, the decrease in PaCO2 induced by CTGI correlated well with PaCO2 values before CTGI (r = 0.58, p < 0.002) and with instrumental dead space-to-tidal volume ratio (r = 0.54, p < 0.005).

CONCLUSION

CTGI may be a useful adjunct to conventional ventilation in preterm neonates with respiratory disease, enabling an increase in CO2 clearance or a reduction in ventilatory pressure.

Continuous tracheal gas insufflation in preterm infants with hyaline membrane disease. A prospective randomized trial

In mechanically ventilated neonates, the instrumental dead space is a major determinant of total minute ventilation. By flushing this dead space, continuous tracheal gas insufflation (CTGI) may allow reduction of the risk of overinflation. We conducted a randomized trial to evaluate the efficacy of CTGI in reducing airway pressure over the entire period of mechanical ventilation while maintaining oxygenation. A total of 34 preterm newborns, ventilated in conventional pressure-limited mode, were enrolled in two study arms, to receive or not receive CTGI. Transcutaneous Pa(CO(2)) (tcPa(CO(2))) was maintained at 40 to 46 mm Hg in both groups to ensure comparable alveolar ventilation. Respiratory data were collected several times during the first day and daily until Day 28. Both groups were similar at the time of inclusion. During the first 4 d of the study, the difference between peak pressure and positive end-expiratory pressure was significantly lower in the CTGI group by 18% to 35%, with the same tcPa(CO(2)) level and with no difference in the ratio of tcPa(O(2)) to fraction of inspired oxygen (245 +/- 29 versus 261 +/- 46 mm Hg [mean +/- SD] over the first 4 d). Extubation occurred sooner in the CTGI group (p < 0.05), and the duration of mechanical ventilation was shorter (median: 3.6 d; 25th to 75th quartiles: 1.5 to 12.0 d; versus median: 15.6 d; 25th to 75th quartiles: 7.9 to 22.2; p < 0.05) than in the non-CTGI group. CTGI allows the use of low-volume ventilation over a prolonged period and reduces the duration of mechanical ventilation.

Chronic progressive external ophthalmoplegia with ragged-red fibers: clinical, morphological and genetic investigations in 43 patients

The evaluation of the severity of progressive external ophthalmoplegia (PEO) with ragged-red fibers in muscle, at the onset of the disease, when PEO is most often the only presenting symptom, is a difficult problem in neurological practice. In order to address that issue, we have performed a comparative analysis of the clinical, morphological and molecular characteristics of 43 patients affected with that form of ocular myopathy. Quantification of mitochondrial accumulation was performed with an image analysis application on muscle sections stained with succinate dehydrogenase histochemical reaction. The proportion of muscle fibres appearing as cytochrome c oxidase deficient was used as an index of the muscle-energy defect. Muscle mitochondrial DNA deletions were detected, localized and quantitated by Southern blot analysis. Point mutations were screened in five transfer RNA genes in the mtDNA (tRNA(Leucine (UUR)), tRNA(Lysine), tRNA(Glutamine), tRNA(Isoleucine) and tRNA(Formylmethionine)) by a denaturing gradient gel electrophoresis technique. This investigation confirmed the high frequency of mtDNA deletions or point mutations in PEO. At the onset of the disease, no clinical, morphological or molecular features could predict whether PEO would remain isolated or become part of a more severe multisystem disease. However, patients with mtDNA deletions were characterized by more severe ophthalmoplegia of earlier onset. Their muscle alterations were roughly parallel in severity to the proportion of deleted mtDNA molecules in muscle. Patients with a multitissular disease and mtDNA deletions were always sporadic cases and their clinical presentation was, most often, closely related to Kearns Sayre syndrome.

Efficacy of dead-space washout in mechanically ventilated premature newborns

The prosthetic dead space makes a significant contribution to the total dead space in low-birth-weight premature newborns receiving artificial ventilation in response to respiratory distress. Use of an endotracheal tube with capillaries molded into the tube wall enables washout of the dead space without insertion of a tracheal catheter. In 10 premature newborns (mean gestational age, 27.5 +/- 2.2 wk; mean weight, 890 +/- 260 g) receiving continuous positive-pressure ventilation (Paw = 12.7 +/- 1.8 cm H2O; FIO2 = 39 +/- 17%), tracheal gas insufflation (TGI) for CO2 washout was conducted using this technique. The flow of tracheal insufflation (0.5 L/min) was derived from the inspiratory line of the ventilator circuit and blown into the trachea. Intratracheal pressures showed little or no TGI-related modification ( < 1 cm H2O). A control system enabled TGI discontinuation in the event of a pressure rise. At constant ventilation pressure, PaCO2 decreased by 12.1 +/- 5.9 mm Hg (delta PaCO2 = -26 +/- 12%) under TGI, whereas PaO2 remained unchanged. While maintaining PaCO2 constant, peak inspiratory pressure (PIP) was decreased by 5.4 +/- 1.7 cm H2O (delta PIP = -22.0 +/- 8.3%). TGI showed immediate efficacy (PCO2 reduction of at least 5 mm Hg) in nine of the 10 newborns who then received chronic TGI (14 to 138 h). TGI appears to be an effective method, suitable for long-term clinical application, enabling a reduction in the aggressive nature of conventional ventilation.

Severe resistance to insulin and insulin-like growth factor-I in cells from a patient with leprechaunism as a result of two mutations in the tyrosine kinase domain of the insulin receptor

We studied the biological properties of insulin receptors (IRs) and insulin-like growth factor-I (IGF-I) receptors in cultured fibroblasts from a patient with leprechaunism (leprechaun Par-1). Patient cells displayed normal insulin binding capacity and affinity. Basal in vivo autophosphorylation and in vitro exogenous kinase activity of patient IRs were elevated twofold to threefold compared with control receptors, and insulin had no further effect on these processes. Moreover, patient IRs were unable to promote the stimulation of metabolic and mitogenic pathways. IR substrate-1 (IRS-1) and mitogen-activated protein (MAP) kinase tyrosine phosphorylation and glycogen and DNA synthesis were not increased in the basal state in patient fibroblasts and were also insensitive to the stimulatory effect of insulin. As for IGF-I, although binding and receptor kinase activity were normal, the ability to stimulate glycogen and DNA synthesis was altered in patient cells. Two mutant alleles of the IR gene were detected by denaturing gradient gel electrophoresis (DGGE) and direct sequencing. The maternal allele contained a point mutation in exon 18 encoding the tryptophan-for-arginine substitution at position 1092, and the paternal allele had a point mutation in exon 20 substituting lysine for glutamic acid at codon 1179. Thereby, leprechaun Par-1 was a compound heterozygote for two missense mutations located in the IR beta-subunit. The present investigation provides the first evidence that leprechaunism can be causally related to structural alterations in the tyrosine kinase domain of the IR. These alterations result in severe impairment of insulin and IGF-I action.

Administering atropine and ketamine before less invasive surfactant administration resulted in low pain scores in a prospective study of premature neonates

AIM

Less invasive surfactant administration (LISA) can avoid tracheal intubation for neonatal respiratory distress syndrome, but can be painful because it requires laryngoscopy. The aim of this study was to assess the efficacy and tolerance of intravenous atropine plus ketamine administration before LISA.

METHODS

We conducted a prospective observational study of all premature infants hospitalised in our French neonatal intensive care unit treated with LISA between March 2015 and March 2016. Ketamine was titrated by 0.5 mg/kg increments. The technical conditions, pain scores, emergent intubations and vital signs were collected and analysed.

RESULTS

Values are reported as medians (interquartile ranges). We included 29 patients with a gestational age of 29.6 (28.6-30.9) weeks and birth weight of 1290 (945-1600) grams. Technical conditions were satisfying for 24 infants (83%). The Faceless Acute Neonatal Pain Scale score was 2 (2-4); seven infants (24%) required tracheal intubation before LISA could be performed; 17 (59%) had a pulse oxymetry value under 80% that lasted more than 60 seconds. Heart rate and mean arterial blood pressure transiently increased.

CONCLUSION

Atropine plus ketamine before LISA resulted in low pain scores and stable haemodynamic parameters, but prolonged desaturations or apnoea leading to tracheal intubation were frequently observed.

Mosaic trisomy 15 and hemihypertrophy

We report a case of mosaic trisomy 15 with mental retardation, facial dysmorphism, and hemihypertrophy, but no manifestations of Prader-Willi or Angelman syndromes. Mosaic trisomy 15 (11%) was discovered at the amniocentesis. Uniparental disomy for chromosome 15 was excluded by molecular analysis. Post-natal blood karyotype and examination were normal. Mosaic was confirmed on skin fibroblasts, placenta and cord. Evolution was marked by progressive right hemi-hypertrophy, and developmental delay. Our case is the first patient reported with hemihypertrophy associated with mosaic trisomy 15. The relevant literature is reviewed.

PAR-CLIP: A Method for Transcriptome-Wide Identification of RNA Binding Protein Interaction Sites

During post-transcriptional gene regulation (PTGR), RNA binding proteins (RBPs) interact with all classes of RNA to control RNA maturation, stability, transport, and translation. Here, we describe Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP), a transcriptome-scale method for identifying RBP binding sites on target RNAs with nucleotide-level resolution. This method is readily applicable to any protein directly contacting RNA, including RBPs that are predicted to bind in a sequence- or structure-dependent manner at discrete RNA recognition elements (RREs), and those that are thought to bind transiently, such as RNA polymerases or helicases.

Phenotype-karyotype correlations in dup(18q): report of a case and review

We report on a case of dup(18q) due to de novo translocation 46,XX,-21,t(18;21)(18qter----cen----21qter). The patient had many characteristic signs of full trisomy 18 except for internal organ malformations and early death. We review the phenotype-karyotype correlations between full trisomy 18 and dup(18q) and discuss the possibility of the existence of "critical zone(s)" at the proximal or/and distal region of 18q responsible for most signs of trisomy 18, such as congenital heart defect and early death.

[Psychologic management of extreme prematurity]

The ongoing progress in neonatal intensive care is modifying the psychic context of prematurity for all the partners, infants as well as parents and physicians. Comfort and prognosis of preterm infants have much improved. Since newborns under 24 weeks of gestational age are now surviving, they spend approximately half the duration of pregnancy out of the maternal uterus. All the psychological issues of such an early separation have to be considered, including the developmental outcome of a sensorial environment which is quite different from the intra-uterine one. Research has been developing in this field. The cooperation between neonatalogists and psychologists has been profitable to parents. Problems linked to the separation, such as difficulty in representing the infant, are no more frequent owing to the attention paid to the mother-child bond and subsequent early contacts. What is forward now is the impact of an hyper technical world of intensive care on the parents, and of the strange aspect of the tiny baby surrounded by engines and tubes. Such an overpresence of reality often results in a reaction of traumatic daziness among parents. The cooperation of the whole staff is necessary for the resumption of an imaginary process of psychic functioning. Finally, the survival of very-low-birth-weight infants confronts the neonatalogists with some delicate ethical questions. Psychiatrists and psychologists might have an important part to play in aiding the profession in its sorting out of these ethical issues.

Disseminated bronchoalveolar keratinocyte plugs in severe neonatal congenital lamellar ichthyosis

We present here a case of congenital lamellar ichthyosis responsible for neonatal death immediately after delivery due to obstruction by bonchoalveolar keratinocyte plugs. The main interest of this case was to confirm in utero amniotic fluid movement into the distal airways by fetal breathing or gasping.

Nationwide outbreak of Salmonella enterica serotype 4,12:i:- infections in France, linked to dried pork sausage, March-May 2010

In May 2010, a nationwide excess of infections with the specific monophasic variant Salmonella enterica serotype 4,12:i:- was investigated in France. Subtyping with multilocus variable number of tandem repeats analysis revealed a distinct epidemic strain within this excess. Epidemiological investigations identified a dried pork sausage sold by a particular chain of supermarkets as the likely vehicle of transmission. The suspected batches have been withdrawn and recalled.