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Biomedical subjects

D K Ng

Publications and source records attributed to D K Ng.

26 records · Page 2Linked to original sources
PubMed2000

Use of montelukast in the treatment of early childhood wheezing from clinical experience with three cases.

Leukotrienes were found to be raised in respiratory syncytial virus bronchiolitis. Montelukast is a cysteinyl leukotrienes antagonist. We report our experience with the use of montelukast in three young children from 5-months to 20-months old. The first case was a 5-month-old boy with previous good health. He had prolonged respiratory distress secondary to adenovirus type 3 infection. The second case was a 20-month-old boy with bronchopulmonary dysplasia. He had respiratory syncytial virus and an adenovirus type 3 infection leading to prolonged wheeze. The third case was a 20-month-old girl with chronic lung disorder after an episode of severe E. coli pneumonia at 1 month old. She developed acute virus-negative severe wheeze after a few days of running nose and low-grade fever. All three cases responded poorly to inhaled steroids and bronchodilators. Addition of montelukast was associated with marked clinical improvement within 1 week. The three cases were very heterogeneous and differed from usual simple virus-induced acute bronchiolitis. The use of multiple drugs including montelukast did not enable any definite conclusions; however, the addition of montelukast was closely related to clinical improvement. Further studies in the use of montelukast in severe virus-induced bronchiolitis are warranted.

Acetates↗
PubMed1999

Characterization of Urtica dioica agglutinin isolectins and the encoding gene family.

Urtica dioica agglutinin (UDA) has previously been found in roots and rhizomes of stinging nettles as a mixture of UDA-isolectins. Protein and cDNA sequencing have shown that mature UDA is composed of two hevein domains and is processed from a precursor protein. The precursor contains a signal peptide, two in-tandem hevein domains, a hinge region and a carboxyl-terminal chitinase domain. Genomic fragments encoding precursors for UDA-isolectins have been amplified by five independent polymerase chain reactions on genomic DNA from stinging nettle ecotype Weerselo. One amplified gene was completely sequenced. As compared to the published cDNA sequence, the genomic sequence contains, besides two basepair substitutions, two introns located at the same positions as in other plant chitinases. By partial sequence analysis of 40 amplified genes, 16 different genes were identified which encode seven putative UDA-isolectins. The deduced amino acid sequences share 78.9-98.9% identity. In extracts of roots and rhizomes of stinging nettle ecotype Weerselo six out of these seven isolectins were detected by mass spectrometry. One of them is an acidic form, which has not been identified before. Our results demonstrate that UDA is encoded by a large gene family.

Amino Acid Sequence↗
PubMed1999

Neonatal Marfan syndrome: a case report.

A case of neonatal Marfan syndrome is presented. The patient was noted to have cardiomegaly and tricuspid regurgitation on antenatal ultrasound scan. She was born with long, slender fingers and toes, an aged appearance and non-paralytic hypotonia. Echocardiogram revealed a dilated right atrium, right ventricle, dysplastic tricuspid valve and severe tricuspid regurgitation. She subsequently died of severe heart failure. Post-mortem examination showed the pathological features of lobar emphysema and cystic medial necrosis of the aorta. These features supported the diagnosis of neonatal Marfan syndrome. Nucleotide sequencing showed substitution of G by A at codon 1032 in exon 25 located in the long arm of chromosome 15. This resulted in the substitution of a cysteine by a tyrosine. A de novo mutation is suggested by the absence of affected family members.

Cardiomegaly↗
PubMed1999

Use of infrared emission detection thermometer in Chinese neonates.

OBJECTIVE: To evaluate the reproducibility of Thermoscan, an infrared emission detection ear thermometer, and to establish the normal reference range of ear temperature in Chinese neonates. METHODS: Neonates were recruited from the inpatients population with exclusion of those suffering from infections. RESULTS: Forty-nine neonates were recruited with 1,115 temperature taking sessions. Mean left ear temperature was 36.64 degrees C +/- 0.35 degree C. Mean right ear temperature was 36.64 degrees C +/- 0.37 degree C. Clinical repeatability for left and right ear was 0.17 degree C and 0.17 degree C, respectively. CONCLUSION: Thermoscan produced reproducible results in Chinese neonates. The normal range of ear temperature for Chinese neonates is 35 degrees C to 37 degrees C. Ear temperature > 37.8 degrees C should be regarded as fever.

Asian People↗
PubMed1997

Positive selection induces CD4 promoter and enhancer function.

Developmental expression of the CD4 gene in mature T cells is controlled by at least four transcriptional control elements: a promoter, two enhancers and a silencer. In this report we use a transgenic approach to study the mechanisms in which these elements interact to convey appropriate tissue- and cell-specific expression at all stages of T cell development. Our data indicate that the control of CD4 gene expression requires the interaction of multiple elements functioning in different combinations at different stages of T cell development. Expression of the CD4 gene in immature CD4+CD8+ thymocytes requires a third enhancer element located in the 3' flanking region of the CD4 gene. Interestingly, the CD4 promoter and proximal/distal enhancers first begin to function at the HSAlo CD69lo H-2Khi CD4 single-positive stage; cells of this phenotype are believed to have survived positive selection. These data indicate that the CD4 promoter and late enhancer elements are induced by positive selection; thus, the final maturation process is an active event that requires the initiation of a novel program of gene expression.

Animals↗
PubMed1997

Paediatric upper gastrointestinal endoscopy: a 2-year review.

OBJECTIVE: To review the paediatric upper gastrointestinal endoscopy service in a paediatric department in Hong Kong. METHODS: Records of all endoscopies undertaken in this department from May 1995 to January 1996 were retrieved and analysed. RESULTS: The commonest indication for upper endoscopy was dyspepsia with 88% positive histological findings. Helicobacter pylori (H. pylori) was found in 25% of this group of children. CONCLUSION: Paediatric upper gastrointestinal endoscopy service is invaluable in a paediatric department by providing useful diagnostic information which would otherwise be missed.

Child↗
PubMedDate not supplied

Formation of NADP(H) analogs of tobacco-specific nitrosamines in rat liver and pancreatic microsomes.

The metabolism of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), was examined in rat pancreatic microsomes. No pyridine N-oxidation or alpha-hydroxylation were observed in these preparations. However, one unidentified metabolite of NNAL (unknown A) and two unknown metabolites of NNK (unknowns B and C) were formed. These metabolites were also detected in rat liver microsomal incubations of NNK and NNAL. Studies using [5-3H]-NNK and [Me-3H]NNK demonstrated that the metabolites contained both the pyridyl and methyl portions of the parent compound. Similar results were obtained with NNAL. Formation of unknown C required active microsomes, NADP+, and an NADPH regenerating system. The regenerating system was not required for the formation of NNAL unknown metabolite A or NNK unknown metabolite B. Chemical characterization of unknowns A and B by NMR, UV, and electrospray ionization MS demonstrated that they are NADP+ analogs in which the nicotinamide portion has been replaced by NNAL or NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol adenosine dinucleotide phosphate [(NNAL)ADP+] and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone adenosine dinucleotide phosphate [(NNK)ADP+]. Unknown C was identified as (NNK)ADPH. Both (NNK)ADP+ and (NNK)ADPH were formed from NNK while only (NNAL)ADP+ was produced from NNAL. These NADP+ derivatives were also formed when porcine brain NAD+ glycohydrolase was incubated with NADP+ and NNK or NNAL. These results indicate that NNK and NNAL are substrates for rat liver and pancreatic microsomal NAD+ glycohydrolase-catalyzed transglycosylation reactions.

Adenosine Diphosphate↗