Single-nucleotide-resolution sequencing of human N6-methyldeoxyadenosine reveals strand-asymmetric clusters associated with SSBP1 on the mitochondrial genome

N6-methyldeoxyadenosine (6mA) is a well-characterized DNA modification in prokaryotes but reports on its presence and function in mammals have been controversial. To address this issue, we established the capacity of 6mA-Crosslinking-Exonuclease-sequencing (6mACE-seq) to detect genome-wide 6mA at single-nucleotide-resolution, demonstrating this by accurately mapping 6mA in synthesized DNA and bacterial genomes. Using 6mACE-seq, we generated a human-genome-wide 6mA map that accurately reproduced known 6mA enrichment at active retrotransposons and revealed mitochondrial chromosome-wide 6mA clusters asymmetrically enriched on the heavy-strand. We identified a novel putative 6mA-binding protein in single-stranded DNA-binding protein 1 (SSBP1), a mitochondrial DNA (mtDNA) replication factor known to coat the heavy-strand, linking 6mA with the regulation of mtDNA replication. Finally, we characterized AlkB homologue 1 (ALKBH1) as a mitochondrial protein with 6mA demethylase activity and showed that its loss decreases mitochondrial oxidative phosphorylation. Our results show that 6mA clusters play a previously unappreciated role in regulating human mitochondrial function, despite 6mA being an uncommon DNA modification in the human genome.

Evaluation of family-centred practices in the early intervention programmes for infants and young children in Singapore with Measure of Processes of Care for Service Providers and Measure of Beliefs about Participation in Family-Centred Service

BACKGROUND

The primary purpose of this study was to report on an evaluation of the perceptions and beliefs of service providers towards family-centred practices in 11 early intervention programmes for infants and young children in Singapore.

METHODS

The Measure of Processes of Care for Service Providers (MPOC-SP) and Measure of Beliefs about Participation in Family-Centred Service (MBP-FCS) were administered to 213 service providers made up of teachers, therapists, psychologists and social workers providing centre-based therapy to children with special needs who were below the age of 6 years.

RESULTS

Exploratory factor analyses were performed with both scales. Nineteen of the 27 MPOC-SP items were retained and supported the original four-factor structure model. The exploratory factor analyses on MBP-FCS provided a less satisfactory outcome. Fourteen of the 28 items were retained and these loaded onto four factors. The two factors relating to Beliefs about benefits of FCS and Beliefs about the absence of negative outcomes from FCS failed to emerge as separate factors. Further multiple regressions indicated that more direct work with families and positive self-efficacy in implementing FCS contributed significantly to explaining service providers' positive perception towards family-centred practice in service delivery.

CONCLUSIONS

This is the first time MPOC-SP and MBP-FCS were administered to a population in an Asian context. While MBP-FCS would benefit from further development work on its construct, MPOC-SP offered important insights into service providers' perspectives about family-centred practices that would have useful implications for professional and service development.

Intraoperative cholangiography facilitates simple transcystic clearance of ductal stones in units without expertise for laparoscopic bile duct surgery

BACKGROUND

In the absence of facilities and expertise for laparoscopic bile duct exploration (LBDE), most patients with suspected ductal calculi undergo preoperative endoscopic duct clearance. Intraoperative cholangiography (IOC) is not performed at the subsequent laparoscopic cholecystectomy. This study aimed to investigate the rate of successful duct clearance after simple transcystic manipulations.

METHODS

This prospective study investigated 1,408 patients over 13 years in a unit practicing single-session management of biliary calculi. For the great majority, IOC was attempted. Abnormalities were dealt with by flushing of the duct, glucagon injection, Dormia basket trawling, choledochoscopic transcystic exploration, or choledochotomy.

RESULTS

Of 1,056 cholangiograms performed (75%), 287 were abnormal (27.2%). Surgical trainees, operating under supervision, successfully performed 24% of all cholangiograms. Of 396 patients admitted with biliary emergencies, 94.1% had abnormal cholangiograms. Of the 287 patients with abnormal IOCs, 9.4% required no intervention, 18% were clear after glucagon and flushing, and 13% were cleared using Dormia basket trawling under fluoroscopy. A total of 95 patients required formal LBDE, and 2 required postoperative endoscopic retrograde cholangiopancreatography (ERCP). No postoperative ERCP for retained stones was required after simple transcystic manipulation. Eight conversions occurred, one during a transcystic exploration. Follow-up evaluation continued for as long as 6 years in some cases. Two patients had recurrent stones after LBDE and a clear postoperative tube cholangiogram.

CONCLUSION

In this series, 10% of the abnormal cholangiograms occurred in patients without preoperative risk factors for bile duct stones. Altogether, 88 IOCs (31%) were cleared after either simple flushing or trawling with a Dormia basket. Formal LBDE was not required for 40% of abnormal cholangiograms. Simple transcystic manipulations to clear the bile ducts justify the use of routine IOC in units without laparoscopic biliary expertise.

Detection of betanodavirus in juvenile barramundi, Lates calcarifer (Bloch), by antigen capture ELISA

Betanodavirus infection of fish has been responsible for mass mortalities in aquaculture hatcheries worldwide. Betanodaviruses possess a bipartite single-stranded RNA genome consisting of the 3.1 kb RNA1 encoding an RNA-dependent RNA polymerase and the B2 protein, while the 1.4 kb RNA2 encodes the viral nucleocapsid protein, alpha. A panel of six monoclonal antibodies against the alpha protein of greasy grouper nervous necrosis virus (GGNNV) was developed for use in diagnostics. All antibodies reacted with native and recombinant alpha in immunoblot and indirect immunofluorescence assays. Each of the monoclonal antibodies reacted against discrete regions of the alpha protein, though none reacted with the extreme C-terminal region of the protein. One of the monoclonal antibodies, specific for the K151-T246 region of alpha, was used for the development of an antigen capture ELISA. In this assay we could detect 10(3)-10(4) TCID(50) units of virus derived from infected tissue culture supernatants. Head tissue extracts prepared from experimentally infected barramundi, Lates calcarifer, juveniles were assayed for GGNNV using the antigen capture assay and a clear increase in alpha antigen was detected from 5 to 15 days post-challenge. The assay thus represents a useful method for field-based detection of betanodavirus in fish hatcheries.

A novel FUCA1 mutation causing fucosidosis in a Chinese boy

We report a 6-year-old boy with an intermediate form of fucosidosis.

Reproduction in a patient with trisomy 8 mosaicism: case report and literature review

We describe a patient with trisomy 8 mosaicism followed through a sixth pregnancy and discuss issues in phenotypic and genotypic variability, the risk for neoplasia, and reproductive risks.

Heterogeneity of neurological syndromes in survivors of grade 3 and 4 periventricular haemorrhage

To evaluate the topographical neurological distribution, patterns of abnormal tone and related functional neuromotor impairment after grade 3 and grade 4 intraventricular/periventricular haemorrhage (IPVH), 33 children with previous grade 3 or 4 IPVH of mean gestational age 30.9 weeks (range 25-40 weeks) and mean birth weight 1743 g (range 866-3600 g) were examined neurologically at 4.7 years (range 0.75-10.8 years). Neurological signs were absent in 10/33 cases which were equally distributed between the grade 3 and grade 4 IPVH groups. The largest single topographical neurological distribution was hemiparesis in 8/23, followed jointly by diplegia (cerebral paraplegia) in 6/23 and triplegia in 6/23 cases and finally quadriplegia in 3/23 cases. Grade 4 IPVH tended to result in asymmetrical syndromes, accounting for 7/8 cases of hemiparesis and 5/6 cases of triplegia, whereas all 3/3 cases of quadriplegia followed grade 3 IPVH. The 6/23 cases of diplegia were shared between the grade 3 and grade 4 IPVH groups. Tone was normal in 7/8 of the hemiparetic subjects. Dystonia was the commonest tone abnormality, affecting 8/23 children with neurological disturbance, followed by ataxia/hypotonia in 4/23 and mixed dystonia/hypotonia in 3/23. Only 1/23 cases had signs of spasticity. Spasticity is rare following severe IPVH. Diplegic children had a better functional neuromotor grade than hemiparetic children, who in turn did better than triplegic children. Ataxia hypotonia resulted in better functional outcome than dystronia, which in turn was more favourable than mixed tone patterns. Cranial imaging by ultrasound (US) or computed tomographic (CT) scanning proved an unreliable prognostic indicator except in the case of hemiparesis, for which US scans correctly predicted the affected side in 5/7 cases. The neurological syndromes following severe IPVH differ from the classical encephalopathy of prematurity, and this should lead to a re-appraisal of the trends in the prevalence of cerebral palsy. Caution should be exercised in the interpretation of cranial imaging with regard to pessimistic prognoses in the presence of changes or undue optimism in their absence.

Neurological outcome following neonatal post-haemorrhagic hydrocephalus: the effects of maximum raised intracranial pressure and ventriculo-peritoneal shunting

The neuromotor outcome of 33 survivors of grade 3 or 4 neonatal post-haemorrhagic hydrocephalus born between 1975 and 1988 was assessed at a mean age of 4.7 years (9 months to 13 years). Two outcomes were determined: 12 patients were either normal (10 or had neurological signs without functional impairments (2), while 21/33 were moderately (16), severely (2), or profoundly impaired (3). Intracranial pressure (ICP) was measured in 26/33 patients (4-40 mm Hg): 2 had normal pressures (< 5.6 mm Hg) and were normal. Raised ICP was not significantly different between outcome groups. Twenty-seven children were shunted; 10/27 had five or more operations (up to 14) and all of these had abnormal neurological outcomes, whereas the number of children with 1-4 shunt procedures was equal in both outcome groups. The rise in morbidity after the fourth shunt procedure may be associated with the ventriculitis suffered by 9 of the 10 patients with more than four shunts (P < 0.01): this compares with 4/14 cases of ventriculitis in the children with 2-4 shunts and no cases of infection in the 3/27 who were shunted once. Outcome was independent of antenatal and perinatal factors including the age at or mode of presentation, and was unrelated to grade of intraventricular haemorrhage or parenchymal changes on ultrasound or CT scanning.

CONCLUSION

for these small numbers, adverse outcome is statistically related to more than four shunt procedures and ventriculitis but independent of maximum ICP or other perinatal factors.

Ganglioneuroma of the spinal cord

This report describes a 2-year-old boy who harbored an intramedullary ganglioneuroma involving almost the entire length of the spinal cord. The terminology, pathology, and neurobiological behavior of this tumor is discussed.

Molybdenum(VI) complexes of Schiff bases derived from salicylaldehyde and 2-aminoethanethiol (cysteamine)

The reaction of salicylaldehyde and 2-aminoethanethiol (cysteamine) in methanol results in two distinct products: a yellow oil, 2-(2-mercaptoethyliminomethyl)phenol, and a yellow crystalline solid, 2,2'-[dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenol, which is an oxidation product of the former. The latter compound may also be prepared from salicylaldehyde and 2,2'-dithio-bis(ethylamine) (cystamine) in methanol. 2-(2''-Mercaptoethyliminomethyl)phenol reacts with MoO2(acac)2 (acac = pentane-2,4-dionate) in methanol to yield a red crystalline solid with empirical formula MoO2(mep) [mep = 2-(2"- mercaptoethyliminomethyl)phenolate]. This red solid exists as a dimer in the solid state. It forms adducts with dimethyl sulfoxide, hexamethylphosphoric acid triamide and pyridine. 2,2'-[Dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenol reacts with MoO2(acac)2 to yield a pale yellow solid. It is a monomeric compound whose formula is MoO2(dbp) {dbp = 2,2'- [dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenolate}. It does not form an adduct and is decomposed by an excess of tetramethylammonium hydroxide in methanol.