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Biomedical subjects

S C Ng

Publications and source records attributed to S C Ng.

At least 145 records · Page 8Linked to original sources
PubMed1996

Coronary stents in the management of coronary artery disease review of first 100 stents.

This is a review of the first 100 coronary stents implanted for the indications of PTCA restenosis, acute or threatened closure and De Novo lesions. The success rates were high and complications rates were low. Subacute stent thrombosis rates were low and stenting for De Novo lesions in > 3.0 mm arteries provide the best short and long term results. Six months restenosis rate was low. Stent assisted high pressure balloon angioplasty is an important advance.

Adult↗
PubMed1996

The first frozen embryo donation pregnancy for hypergonadotrophic hypogonadism in Singapore--hormonal profile and obstetric outcome.

This is the first report in South East Asia of a singleton frozen embryo donation pregnancy for hypergonadotrophic hypogonadism. The hormonal profile was compared with that of a control group of normal uncomplicated singleton pregnancies in Singapore. The plasma beta hCG levels were lower compared to those of our normal uncomplicated singleton pregnancies at 2 to 3 weeks after the embryo transfer but became comparable at 4 to 5 weeks after embryo transfer. The successful vaginal delivery and the obstetric complications developed in this case are discussed.

Adult↗
PubMed1996

Update on micromanipulation techniques for assisted conception.

This article reviews the progress in the field of micromanipulation in the past year. The major event has been the wide application of intracytoplasmic sperm injection. Other advances include haploid spermatid injection and the development of successful mouse models for intracytoplasmic sperm injection. There is now increasing awareness of the genetic basis of male infertility and its possible impact on how we offer treatment.

Animals↗
PubMed1995

Combinatorial interaction of human bcl-2 related proteins: mapping of regions important for bcl-2/bcl-x-s interaction.

Human bcl-2 family of genes including bcl-2, bcl-x-l, bcl-x-s, and bax has been shown to be functionally involved in apoptosis. We applied a yeast two-hybrid system to demonstrate that bcl-2, bcl-x-l, bcl-x-s, and bax proteins can interact with each other directly. All bcl-2 family members except bax were shown to be capable of homo-interactions. By using deletion and point mutations, the interaction domains for bcl-2 and bcl-x-s were elucidated. The BH1 domain and the membrane anchoring region at the C-terminal half of the bcl-2 protein are required for its interaction with bcl-x-s. On the other hand, the N-terminal region consisting of codons 24 to 78 of bcl-x-s interacts with bcl-2.

Base Sequence↗
PubMed1995

Acquired platelet dysfunction with eosinophilia in white children.

Acquired platelet dysfunction associated with eosinophilia has been described mainly in indigenous Southeast Asian and East Indian children. We describe two white boys in whom this disorder developed after they had lived in Malaysia for 12 to 18 months. Acquired platelet dysfunction associated with eosinophilia should therefore be considered in children who, after a visit to this region, have easy bruising and esoinophilia.

Blood Platelet Disorders↗
PubMed1995

Intracytoplasmic sperm injection of mouse oocytes with 5 mM Ca2+ at different intervals.

The objective of this investigation was to determine whether intracytoplasmic sperm injection (ICSI) can be performed in the mouse. Metaphase II oocytes were obtained from F1 hybrid mice (C57BL x CBA) by i.p. injections of 10 IU pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) administered 48 h apart. Oocytes with cumulus oophorus were retrieved 13-14 h post HCG. Cumulus was dispersed with 0.1% hyaluronidase. Mouse spermatozoa were obtained from the cauda epididymides of males of the same strain. The spermatozoa were processed by the standard swim-up procedure. The harvested spermatozoa were then incubated for 1.5 h to allow capacitation. Healthy oocytes were injected with 3-4 pl 5 mM Ca2+, followed by one live morphologically normal spermatozoon into the cytoplasm at intervals of 0, 0.5, 1, 2 and 3 h. The proportion of 2-cell embryos that developed from oocytes injected with Ca2+ and spermatozoa ranged between 29.5 and 36.5% in all groups, with no statistical difference between treatments. Chromosomal analysis showed that two-thirds of the ICSI-derived 2-cell embryos were diploid. The proportion of parthenogenetically activated embryos in the ICSI groups was similar to that in the control group (8-10%) which was injected with Ca2+ and polyvinyl pyrrolidone only. The proportion of blastocysts that developed in culture from the ICSI-derived 2-cell embryos was of the order of 36-42%. Some blastocysts were used for cell number counts. There was a significant increase in total and inner cell mass counts of blastocysts in which the spermatozoon was injected at 2 and 3 h following Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effect of growth hormone therapy in men with severe idiopathic oligozoospermia.

Some studies have suggested that growth hormone (GH) may enhance folliculogenesis in women, and similarly may enhance spermatogenesis in men with hypogonadotrophic hypogonadism. In this prospective open-controlled pilot study, we investigated the effect of daily subcutaneous GH for 5 months in 12 endocrinologically normal men with severe idiopathic oligozoospermia (< 10 million/ml). All the men had normal karyotype and endocrine tests, including a GH response of > 20,000 mU/l to insulin hypoglycaemia. Nine men with similar sperm counts acted as controls. During treatment, each patient was examined monthly, asked for side effects and had glycosylated haemoglobin, glucose and blood counts monitored. Five semen samples were obtained in the 4 months before treatment, two samples per month during treatment and three samples after stopping treatment. The mean insulin-like growth factor I (IGF-I) was normal before treatment and 1 month after ending treatment, at 206 and 182 micrograms/l, respectively, but increased significantly during treatment to 444 micrograms/l (p < 0.0001, ANOVA). The mean (SD) sperm counts were 2.6 (2.5), 2.5 (3.7) and 2.3 (2.1) million/ml before, during and after GH treatment, respectively, and did not show any statistically significant differences (ANOVA). We conclude that GH does not increase or decrease sperm counts in men with severe idiopathic oligozoospermia.

Adult↗
PubMed1995

Aberrant GAP-43 gene expression in Alzheimer's disease.

GAP-43 is a growth-associated phosphoprotein expressed at high levels in neurons during development, axonal regeneration, and neuritic sprouting. GAP-43 gene expression in mature neurons is probably functionally important for the structural remodeling of synapses as required for learning and establishing new memory. The widespread aberrant neuritic growth accompanied by impaired synaptic plasticity in Alzheimer's disease (AD) suggests that abnormal GAP-43 gene expression may contribute to the cascade of neurodegeneration. In the present study, end-stage AD brains exhibited reduced neuronal expression but increased glial cell levels of GAP-43 mRNA and protein. Glial cell localization of GAP-43 gene expression was confirmed by in situ hybridization of cerebral tissue, Northern blot analysis of microdissected cerebral white matter, and independent analysis of astrocytoma cell lines and primary malignant astrocytomas. In addition, in AD, GAP-43 immunoreactivity was translocated from the cytosol to membranes of swollen neuritic (dendritic) and glial cell processes throughout cerebral cortex and white matter. Downregulated and aberrant neuronal GAP-43 gene expression appears to reflect an important molecular lesion that precedes and progresses with the widespread synaptic disconnection and dementia in AD. At the same time, the presence of similar neuronal abnormalities in Pick's disease, diffuse Lewy body disease, Parkinson's disease, and Down syndrome suggests common mechanisms in the respective cascades of neurodegeneration. Finally, the finding of aberrantly increased glial cell GAP-43 gene expression in AD exposes a previously unrecognized neurodegenerative change that may account for the axonal loss and white matter atrophy detected early in the course of disease.

Aged↗
PubMed1995

Carbimazole-induced agranulocytosis treated with granulocyte-macrophage colony stimulating factor--a case report.

Drug-induced agranulocytosis is a potentially fatal complication despite advances in supportive care. A patient with carbimazole-induced agranulocytosis associated with marked depletion of granulocytic precursors in the marrow was treated with granulocyte-macrophage colony stimulating factor (GM-CSF) at a dose of 5 micrograms/kg subcutaneously daily for one week. The absolute neutrophil count rose above 1 x 10(9)/L after one week of GM-CSF therapy. The GM-CSF probably expedited the recovery of the neutrophil count. Further studies are warranted to delineate the role of GM-CSF in the treatment of drug-induced agranulocytosis.

Agranulocytosis↗
PubMed1995

Laparoscopic hysterectomy--a step forward?

Laparoscopic gynaecological surgery has made tremendous progress since the last decade and the introduction of laparoscopic hysterectomy has gained immense popularity amongst both gynaecologists and consumers alike in its short history of 5 years. This review surveys the literature available on this technique and critically evaluates the indications, limitations as well as the benefits and risks of this approach to hysterectomy. There is some evidence presently that laparoscopic hysterectomy may offer benefits to selected patients who otherwise have indications for an abdominal hysterectomy. Overall, the incidence of laparotomy for hysterectomy may be decreased by converting a portion of these patients to the laparoscopically-assisted vaginal approach.

Female↗
PubMed1995

Auto-antibodies in the hospitalised Oriental elderly.

Aches and pains are a common problem in the elderly and often a positive auto-antibody result is difficult to interpret in the given clinical setting. We studied 96 unselected hospitalised Oriental elderly aged 65 years and above to determine the prevalence of auto-antibodies and their clinical significance. Anti-nuclear antibody (ANA) was positive in 33%; commonest titres were low (i.e. 1:40); commonest patterns were speckled and homogeneous; 44% had no known cause for a positive result apart from their age; 37% were taking drugs known to be associated with a positive ANA and 19% had both a disease and a drug known to be associated with a positive ANA. Rheumatoid factor (RF) was positive in 16%; 47% had titres < or = 40 IU/ml and 87% had no known cause of positive RF. Other auto-antibodies tested were negative. We conclude that the prevalence of auto-antibodies in the hospitalised Oriental elderly are common and of no clinical significance if accompanying features of an auto-immune disease are absent.

Aged↗
PubMed1994

Human embryonic behavior in a sequential human oviduct-endometrial coculture system.

Embryonic behavior to blastocyst, hatching, and hatched stages were evaluated in 77, four-cell human embryos that were first grown in oviductal cell coculture and then equally allotted at the eight-cell stage to two coculture systems in a serum-free medium (34 continued on oviductal monolayers, 32 on endometrium monolayers). Sixty-three percent and 40% of embryos expanded and hatched in the sequential oviductal-endometrial coculture system when compared with 41% and 9% in the oviductal system alone, respectively. The sequential coculture system appears to be an improved system over the single human oviductal coculture system.

Culture Techniques↗
PubMed1994

Synthesis, molecular modelling, and NMR structure determination of four cyclic peptide antagonists of endothelin.

A combined distance geometry and molecular mechanics/dynamics (MM/MD) protocol was unable to predict the active conformation of the cyclic pentapeptide inhibitor of endothelin-1 receptor, BQ-123, and two analogues. However, the MM/MD method alone is sufficient to predict the solution conformation of a third analogue. In that one case, the combination of proline at residue 3 and an N alpha-methyl substitution at residue 5 provides enough internal constraints to eliminate conformational flexibility seen in the other three analogues. For this constrained analogue, the 50 lowest energy conformations (out of a set of 500 DGEOM-generated, MM/MD minimized conformations) differ by no more than 3.9 kcal/mol. Thirty three of these 50 conformations have backbone atom RMSDs of less than 0.33 A, relative to the lowest energy conformation. The accuracy of this MM/MD model is verified by determining the solution structure of each of the four analogues with 2D NMR techniques. Each of the cyclic pentapeptides has a well defined solution conformation where a proline residue is clearly in a gamma-turn, leaving the remaining residues in a loose beta-turn. All four experimental NMR conformations agree closely with the MM/MD model.

3T3 Cells↗