[Historical review on obstructive sleep apnea in children]. / Revue historique sur le syndrome d'apnée obstructive du sommeil chez l'enfant.

An historical review on the discoveries on pediatric obstructive sleep apnea syndrome and sleep-disordered breathing is outlined. Starting with the description by Dickens of "Joe" the obese, snoring and sleepy individual, the authors trace more than 50 years of questions and research starting with the lean adult to the child and from the recognition of obstructive sleep apnea syndrome to the outline of upper-airway resistance syndrome. The pathophysiological knowledge on sleep-disordered breathing has evolved over time, as have treatment approaches in children, from tracheostomy to positive-airway-pressure therapy, to adenotonsillectomy with and without orthodontic treatments to oral-facial myofunctional therapy. Co-morbidities of sleep-disordered breathing are multiple, involving cognition, behavioral, and mood disorders, cardiovascular impairment, etc. There have been many advances in a short time due to the investigation of OSAS, but many questions still need responses.

Long-term efficacy of miglustat in paediatric patients with Niemann-Pick disease type C.

Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease characterized by progressive neurological manifestations. Oral miglustat was first approved for the treatment of children and adults with NP-C in Europe in 2009. There are still relatively few published data on the long-term efficacy and safety of miglustat in patients with NP-C in clinical practice. We report the effects of up to 6 years of treatment with miglustat 100 mg t.i.d. in five children. Overall, 3/5 patients displayed progressive dysphagia before starting miglustat, and 4/5 showed marked cognitive and/or motor impairment. The mean age at treatment start was 11.6 years, and the median (range) duration of therapy so far is 4 (4.1 to 6.1) years. No treatment dose alterations were required, but therapy was interrupted for 1-3 months at least once in all patients due to supply issues. Swallowing function was stabilised during miglustat therapy, with no significant increase in Han dysphagia scale or aspiration-penetration index scores among four evaluable patients (p > 0.05). Scores on the mini-mental state examination indicated an improvement in cognitive function during the first 3-6 months of miglustat therapy, followed by stabilisation up to 5 years. Ambulatory function remained stable for at least the first 2 years of treatment in most patients, but there was a trend towards deterioration thereafter, possibly related to treatment interruptions. The safety/tolerability profile of miglustat was similar to previous clinical studies, although reports of gastrointestinal disturbances were rare. Overall, miglustat appeared to stabilise key parameters of neurological disease progression.

Stabilization of blood methylmalonic acid level in methylmalonic acidemia after liver transplantation.

Methylmalonic acidemia with complete mutase deficiency (mut(0) type) is an inborn error of metabolism with high mortality and morbidity. LT has been suggested to be a solution to this disease, but elevation of urinary and blood MMA was still observed after LT. In this study, we measured dry blood spot MMA and its precursor propionyl-carnitine (C3-carnitine) for mut(0) patients. The results revealed that when C3-carnitine rose during metabolic stress, MMA rose exponentially (up to 1000 micromol/L) in patients who did not undergo LT. In patients who underwent LT, MMA rose to 100-200 micromol/L when C3-carnitine reached 10-20 micromol/L. However, when C3-carnitine rose further to 40-50 micromol/L, MMA levels just stayed put. Therefore, LT stabilized blood MMA level, though there might be a threshold for blood MMA clearance by the donor liver. This finding should be critical to understand the long-term outcome for LT in methylmalonic acidemia.

Detection and imaging of non-contractile inclusions and sarcomeric anomalies in skeletal muscle by second harmonic generation combined with two-photon excited fluorescence.

The large size of the multinucleated muscle fibers of skeletal muscle makes their examination for structural and pathological defects a challenge. Sections and single fibers are accessible to antibodies and other markers but imaging of such samples does not provide a three-dimensional view of the muscle. Regrettably, bundles of fibers cannot be stained or imaged easily. Two-photon microscopy techniques overcome these obstacles. Second harmonic generation (SHG) by myosin filaments and two-photon excited fluorescence (2PEF) of mitochondrial and lysosomal components provides detailed structural information on unstained tissue. Furthermore, the infrared exciting light can penetrate several layers of muscle fibers and the minimal processing is particularly valuable for fragile biopsies. Here we demonstrate the usefulness of SHG, combined with 2PEF, to reveal enlarged lysosomes and accumulations of non-contractile material in muscles from the mouse model for the lysosomal storage disorder Pompe disease (PD), and in biopsies from adult and infant PD patients. SHG and 2PEF also detect sarcomeric defects that may presage the loss of myofibrils in atrophying muscle and signify loss of elasticity. The combination of SHG and 2PEF should be useful in the analysis and diagnosis of a wide range of skeletal muscle pathologies.

Deficiency of the carnitine transporter (OCTN2) with partial N-acetylglutamate synthase (NAGS) deficiency.

A patient with recurrent episodes of hyperammonaemia (highest ammonia level recorded 229 micromol/L, normal 9-33) leading to altered levels of consciousness was diagnosed with partial N-acetylglutamate synthase (NAGS) deficiency (9% residual activity) at age 5 years and was treated with ammonia-conjugating agents (Ucephan 250 mg/kg per day and later sodium phenylbutyrate 200-250 mg/kg per day) for 15 years. A chronically low serum carnitine level (pretreatment plasma free carnitine 4 nmol/L, normal 37 +/- 8 nmol/L; total carnitine 8 nmol/L, normal 46 +/- 10) was assumed to be secondary and was treated with supplemental carnitine (30-50 mg/kg per day). Hypoglycaemia (blood sugar 35 mg/dl, normal 70-100), cardiomegaly, and fatty liver were also noted at diagnosis. The patient died unexpectedly at age 20 years. In retrospect, it was learned that the patient had stopped his carnitine without medical consultation several weeks prior to his death. Additional molecular investigations identified two mutations (R254X and IVS3 + 1G > A) in the patient's OCTN2 (SLC22A5) gene, consistent with a diagnosis of primary carnitine deficiency due to carnitine transporter defect. R245X is a founder mutation in Southern Chinese populations. It is unknown whether the original NAGS deficiency was primary or secondary, but molecular analysis of the NAGS gene failed to identify mutations. Urea cycle enzyme expression may be affected by fatty acid suppression of an AP-1 binding site in the promoter enhancer region of the urea cycle gene. Regardless, it is clear that the NAGS abnormality has led to delay of recognition of the OCTN2 defect, and modified the clinical course in this patient.

Treatment of Niemann-Pick disease type C in two children with miglustat: initial responses and maintenance of effects over 1 year.

Niemann-Pick disease type C (NP-C) is a lipid storage disorder characterized by the accumulation of unesterified cholesterol and glycolipids in the lysosomal/late endosomal system of certain cells in the central nervous system (CNS) and visceral organs. Clinical symptoms include progressive neurological deterioration and visceral organomegaly. Miglustat, a small iminosugar molecule approved for the treatment of Gaucher disease, reversibly inhibits glucosylceramide synthase, which catalyses the first committed step in glycosphingolipid synthesis. The physicochemical properties of miglustat allow it to cross the blood-brain barrier and suggest possible benefits in lysosomal storage diseases affecting the CNS. Here, we present findings in two children with NP-C, aged 14 years (patient 1) and 9 years (patient 2), treated with miglustat for 1 year. Before treatment, patient 1 presented with severe difficulties in swallowing and walking, and patient 2 with problems mostly affecting communication and social interaction. Videofluoroscopic studies in patient 1 demonstrated a substantial improvement in swallowing by month 6 of treatment, and ambulation index measurements indicated improved walking. Mini Mental-State Examination (MMSE) assessments in patient 2 showed cognitive improvement by month 6, which was sustained up to month 12. Liver/spleen volume and plasma chitotriosidase activities were stabilized in both cases. There was no weight loss during treatment. Patient 1 experienced severe but self-limiting paresthesia, which was not associated with peripheral neuropathy. We conclude that miglustat can provide therapeutic benefits in CNS symptoms and allows stabilization of systemic disease in childhood-onset NP-C. Further follow-up is crucial to determine the long-term maintenance of these effects.

Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease.

BACKGROUND: Pompe disease is a progressive metabolic neuromuscular disorder resulting from deficiency of lysosomal acid alpha-glucosidase (GAA). Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death. The safety and efficacy of recombinant human (rh) GAA were evaluated in 18 patients with rapidly progressing infantile-onset Pompe disease. METHODS: Patients were diagnosed at 6 months of age and younger and exhibited severe GAA deficiency and cardiomyopathy. Patients received IV infusions of rhGAA at 20 mg/kg (n = 9) or 40 mg/kg (n = 9) every other week. Analyses were performed 52 weeks after the last patient was randomized to treatment. RESULTS: All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group. There was no clear advantage of the 40-mg/kg dose with regard to efficacy. Eleven of the 18 patients experienced 164 infusion-associated reactions; all were mild or moderate in intensity. CONCLUSIONS: Recombinant human acid alpha-glucosidase is safe and effective for treatment of infantile-onset Pompe disease. Eleven patients experienced adverse events related to treatment, but none discontinued. The young age at which these patients initiated therapy may have contributed to their improved response compared to previous trials with recombinant human acid alpha-glucosidase in which patients were older.

Gamma delta T cell receptors.

Gamma delta (gamma delta) T cells are among the least understood components of the immune system. While these cells appear to contribute uniquely to host immune competence, defining their functions in the context of host biology and pathology has been difficult. This is largely because it is unclear what antigens the gamma delta T cell receptor repertoire is directed against. During the past year, there have been noteworthy advances in this area. Their significance in the context of gamma delta T cell biology is discussed.

Identification of variations in the human phosphoinositide 3-kinase p110delta gene in children with primary B-cell immunodeficiency of unknown aetiology.

Our recent study demonstrated that defects in p110delta result in B-cell immunodeficiency that is very similar to that observed in BTK-deficient mice. We revealed that the p110delta fit the B-cell signal transduction complex and played a non-redundant role in the development and function of B cells. In humans, most children with primary B-cell immunodeficiency have mutations in the BTK, whereas a few have defects in the components of the B-cell signal transduction complex. But little is known about the genetic variation of p110delta in children with defects in B-cell immunodeficiency of unknown aetiology. Sixteen patients from 15 unrelated families and 112 normal controls underwent sequence analysis to identify genetic variations of the p110delta. Allele frequency in each group was also analysed and compared. We identified five single base-pair polymorphic nucleotide exchanges in both patient and control groups with similar allele frequencies, which did not contribute to the immunodeficiency. Three of them are novel (m.953A>G, m.1200C>T and m.1561A>G), and the m.953A>G and m.1561A>G nucleotide exchanges are non-synonymous (N253S and T456A, respectively). The novel m.1561A>G was in complete linkage disequilibrium with the known m.873A>G in our study of Taiwanese group. In addition, one novel single base-pair missense mutation, m.3256G>A (E1021K), was identified in one boy with typical clinical features of primary B-cell immunodeficiency and could not be found in either his family or the normal control population. By atomic structural analysis of the amino acid as well as the alignment comparison between species, it resulted in the replacement of the negative-charged amino acid E with the positive-charged amino acid K at codon 1021, located in the highly conservative and important catalytic functional domain. Our findings could shed light on further understanding the polymorphisms of p110delta in B-cell immunodeficiency and different populations. Moreover, the 3256G>A missense mutation raised the attention and warranted further extensive analysis to elucidate the role of p110delta in human immunodeficiency.

Calcium site mutations in cadherin: impact on adhesion and evidence of cooperativity.

This work describes quantitative force and bead aggregation measurements of the adhesion and binding mechanisms of canine E-cadherin mutants W2A, D134A, D103A, D216A, D325A, and D436A. The W2A mutation affects the formation of the N-terminal strand dimer, and the remaining mutations target calcium binding sites at the interdomain junctions. Surface force measurements show that the full ectodomain of canine E-cadherin forms two bound states that span two intermembrane gap distances. The outer bond coincides with adhesion between the N-terminal extracellular domains (EC1) and the inner bond corresponds to adhesion via extracellular domain 3 (EC3). The W2A, D103A, D134A, and D216A mutations all eliminated adhesion between the N-terminal domains, and they attenuated or nearly eliminated the inner bond. The W2A mutant, which does not destabilize the protein structure, attenuates binding via EC3, which is separated from the mutation by several hundred amino acids. This long-range effect suggests that the presence or absence of tryptophan-2 docking allosterically alters the adhesive function of distal sites on the protein. This finding appears to reconcile the multidomain binding mechanism with mutagenesis studies, which suggested that W2 is the sole binding interface. The effects of the calcium site mutations indicate that structural perturbations cooperatively impact large regions of the protein structure. However, the influence of the calcium sites on cadherin structure and function depends on their location in the protein.

Treatment and outcome of Taiwanese patients with 6-pyruvoyltetrahydropterin synthase gene mutations.

Ten cases of tetrahydrobiopterin (BH4) deficiency were identified in 1,337,490 newborns screened in a Chinese population in Taiwan. The high incidence of BH4 deficiency in the Taiwanese population may be explained by a founder effect, since all of the patients revealed 6-pyruvoyltetrahydropterin synthase gene mutations, and grouping N52S and P87S mutations together constituted 88.9% of the disease alleles. BH4 supplementation with restriction of high-protein foods gave control of plasma phenylalanine within normal range, and levodopa itself prevented seizure. However, the average intelligence quotient (IQ) score of these patients was only 76 +/- 14 (56-98). Statistically, the age of starting medication, including 5-hydroxytryptophan (5-HTP), was inversely correlated to IQ scores of these patients. We suggest the combination of BH4, levodopa and 5-HTP as the standard protocol to commence the treatment of BH4 deficiency as early as possible, although prenatal brain damage could have existed.

Nephrotic syndrome in a bone marrow transplant recipient without chronic graft-versus-host disease.

A 5-year-old girl developed severe proteinuria and microscopic hematuria 17 months after allogeneic bone marrow transplantation (BMT) for chronic myeloid leukemia. These nephrotic symptoms occurred during cyclosporin tapering, in the absence of other signs of chronic graft-versus-host disease (GVHD). A renal biopsy revealed focal segmental glomerulosclerosis. After methylprednisolone therapy, the proteinuria gradually decreased. The altered or disordered immune regulation that occurred after BMT may have resulted in the development of nephrotic syndrome.

Suspended rice particles for cultivation of Monascus purpureus in a tower-type bioreactor.

Cultivation of Monascus purpureus (CCRC 31615) for the production of natural pigments was investigated. Traditionally, Monascus species were grown on rice by solid-state culture. For large-scale cultivation, solid-state cultures were associated with some problems such as contamination and scale-up. By using submerged cultures with rice particles, a stirred-tank fermentor was not suitable for submerged cultures as the impeller tended to break the particles into small pieces. A conventional bubble column was also unsuitable as its mixing capability was poor. In the present study, a modified bubble column with wire-mesh draft tubes was employed for the cultivation of M. purpureus. The proposed column had a shorter mixing time and a higher oxygen transfer rate relative to the conventional bubble column. The production of pigments using the proposed column was up to 80% higher than that achieved using the conventional bubble column.