Search PubMed⌕ Search

Biomedical subjects

S H Tan

Publications and source records attributed to S H Tan.

At least 19 recordsLinked to original sources
PubMed2006

Cerclage-wiring-assisted fixation of difficult hand fractures.

Difficult hand fractures with multiple butterfly fragments, multiple cortical splits or intraarticular extension continue to pose a challenge for optimal stable fixation that allows early postoperative mobilisation. In this study, we describe the use of cerclage-wire-assisted fixation of 17 difficult hand fractures in 16 patients. The cerclage wires helped to maintain the reduction, so providing sufficient initial stability for placement of a plate and screws. Stable fixation of the fracture was then accomplished without losing the reduction. One to three cerclages of stainless-steel wires were used for the preliminary fixation. Stable fixation was then accomplished by a bridging or neutralising plate technique. Postoperatively, the fixation was sufficiently stable to allow immediate mobilisation. With an average follow up of 44.5 months, all 17 fractures united without loss of reduction. At final follow-up, the average total active range of motion was 247 degrees (range 220-260 degrees ).

Adolescent↗
PubMed2006

RUNX3 protein is overexpressed in human basal cell carcinomas.

Basal cell carcinomas (BCC), which are the most common form of skin malignancy, are invariably associated with the deregulation of the Sonic Hedgehog (Shh) signalling pathway. As such, BCC represent a unique model for the study of interactions of the Shh pathway with other genes and pathways. We constructed a tissue microarray (TMA) of 75 paired BCC and normal skin and analysed the expression of beta-catenin and RUNX3, nuclear effectors of the wingless-Int (Wnt) and bone morphogenetic protein/transforming growth factor-beta pathways, respectively. In line with previous reports, we observed varying subcellular expression pattern of beta-catenin in BCC, with 31 cases (41%) showing nuclear accumulation. In contrast, all the BCC cases tested by the TMA showed RUNX3 protein uniformly overexpressed in the nuclei of the cancer cells. Analysis by Western blotting and DNA sequencing indicates that the overexpressed protein is normal and full-length, containing no mutation in the coding region, implicating RUNX3 as an oncogene in certain human cancers. Our results indicate that although the deregulation of Wnt signalling could contribute to the pathogenesis of a subset of BCC, RUNX3 appears to be a universal downstream mediator of a constitutively active Shh pathway in BCC.

Blotting, Western↗
PubMed2006

Squamous cell carcinoma developing in two Chinese patients with chronic discoid lupus erythematosus: the need for continued surveillance.

Squamous cell carcinoma (SCC) is a rare late sequel of chronic discoid lupus erythematosus (CDLE). We report two cases of SCC developing in Chinese patients with CDLE. The first patient had prior biopsies from the same site that showed viral warts and the second patient had multiple histologically confirmed viral warts around the vicinity of the previously excised SCC. In this paper, we emphasize the need to be suspicious of warty lesions on skin afflicted by CDLE, and repeat biopsies should be performed if there is failure to respond to conventional therapy.

Adult↗
PubMed2005

Reticulate hyperpigmented scleroderma: a new pigmentary manifestation.

Scleroderma is a systemic disease with a myriad of cutaneous manifestations. Pigmentary disturbances have been described in scleroderma. While diffuse generalized hyperpigmentation and localized hypopigmentation with perifollicular hyper-pigmentation are well recognized, a vascular induced hyperpigmentation has only been recently described. In this paper, we report another unrecognized pigmentary abnormality in a 48-year-old patient who presented with a reticulate hyper-pigmentation affecting the trunk, upper and lower limbs. To our knowledge, cutaneous hyperpigmented reticulate scleroderma has not been reported previously.

Female↗
PubMed2005

Neurothekeomas of the upper limb--case series and clinicopathological review.

Neurothekeomas are rare, benign soft tissue tumours that are considered to be of nerve sheath origin. We present a case series of three patients who have neurothekeomas of the upper limb. There was a remarkably high tumour recurrence rate. The factors contributing to this outcome were studied and a clinicopathological review was performed.

Adult↗
PubMed2005

The prevention of neuroma formation by diathermy: an experimental study in the rat common peroneal nerve.

INTRODUCTION: There have been anecdotal reports of the efficacy of diathermy (electrocoagulation) in the prevention of neuroma formation. However, this has not been investigated in the laboratory. In this experiment involving 40 rats, diathermy was applied to the terminal proximal ends of transected rat common peroneal nerves to evaluate its effect on neuroma formation. MATERIALS AND METHODS: Monopolar and bipolar diathermy set at 45 W, applied for different durations (4 seconds and 10 seconds), were evaluated. Under histological control, the presence of neuroma formation and the diameter of the nerve ends were evaluated at 3 months. The contralateral common peroneal nerve in the same rat served as the control. The dorsal root ganglia of 2 rats in each group were also harvested for histological study. RESULTS: The incidence of neuroma formation was 30% in the group which received high-duration monopolar diathermy (10-second application), versus 90% in the control group (P <0.05). The mean diameter of the nerve ends was smaller at 0.51 mm [standard deviation (SD), 0.29] versus 0.85 mm (SD, 0.24) in the control (P <0.05). The incidence of neuroma formation was 30% in the group which received low-duration monopolar diathermy (4-second application), and 83% in the control group (P <0.05). The diameter was 0.43 mm (SD, 0.14) versus 0.85 mm (SD, 0.28) (P <0.05). High-duration bipolar diathermy applied for 10 seconds, showed a neuroma formation of 25% versus 100% in the control group (P <0.05). The diameter of the nerve ends was 0.48 mm (SD, 0.07) versus 0.79 mm (SD, 0.36) in the control group (P <0.05). The incidence of neuroma formation was 60% in the low-duration bipolar group, which received bipolar diathermy application for 4 seconds, and 90% in the control group (P = 0.25). The diameter of the nerve ends in the low-duration bipolar group was 0.52 mm (SD, 0.24) versus 0.76 mm (SD, 0.40). The incidence of neuroma formation and the difference in diameter in the low duration-bipolar group were both not statistically significant. CONCLUSION: This study demonstrates the effectiveness of monopolar diathermy in reducing the rate of neuroma formation. For bipolar diathermy, an application of 10 seconds was effective in reducing neuroma formation but an application of 4 seconds was not associated with a significant reduction in neuroma formation.

Animals↗
PubMed2004

Motor root conduction block in traumatic brachial plexopathy.

A 31-year old man sustained severe left brachial plexus traction injury. Electrical stimulation demonstrated multilevel motor root conduction block, which reversed after a 4-month period. Motor root conduction studies are useful diagnostic and prognostic adjuncts in the management of brachial plexopathy.

Action Potentials↗
PubMed2004

Investigation of fixation screw pull-out strength on human spine.

For the purpose of fixation and stabilizing the spine, the pull-out strength of the screw is one of the most important factors to be considered. The material properties of the bone, coupled with the principal dimensions of the screw such as major diameter, minor diameter, pitch and purchase length, may affect the pull-out strength of the fixation screw. In this study, the effects of various factors on the bone screw pull-out strength were studied using finite element method of analysis. A three-dimensional finite element model simulating the threaded connection of bone and surgical screw was constructed. The behavior of both the bone and the screw during screw pull-out were analyzed and discussed. The effect of the screw parameters on the screw pull-out strength was also investigated. The results showed that failure of the connection was due to bone shearing which occurred along a cylindrical surface determined by the outer perimeter of the screw and penetrated length. The distribution of the shear stress along the threaded length in the bone was nearly uniform. The effect of the major diameter on the screw pull-out strength was more significant than those of the minor diameter and the pitch. The minor diameter hardly affected the pull-out strength.

Biomechanical Phenomena↗
PubMed2004

Overriding fifth finger: an unusual sign in lower brachial plexopathy.

Hand deformities are often useful clinical signs. To our knowledge, they have not been described in association with brachial plexus lesions. A 28-year-old female presented with sudden left shoulder pain and medial forearm parasthesia. Examination showed the left fifth finger adducting and flexing over the dorsal aspect of the fourth finger. Neurophysiological studies and MRI supported a brachial plexus lesion. The physical sign was not present 5 months post onset and the patient experienced near complete clinical improvement. The unusual physical sign occurred in association with neuralgic amyotrophy. Its occurrence can be explained in terms of transient patchy involvement of nerve fascicles in the brachial plexus.

Adult↗
PubMed2004

Secondary syphilis presenting as a lichen planus-like rash.

We describe a case of secondary syphilis in a 29-year-old man who presented with a severely pruritic lichen planus-like eruption that mimicked a lichenoid drug eruption histologically. Although uncommon, syphilis should be considered in the differential diagnosis of any lichenoid eruption.

Adult↗
PubMed2004

Lymphocytic gastritis-like T cell lymphoma: molecular evidence of an unusual recurrence.

This report describes a patient with a gastric biopsy specimen showing histomorphological and immunohistochemical appearances indistinguishable from those usually present in lymphocytic gastritis, a rare condition of unknown aetiology with a distinctive phenotype. The patient had a history of a biopsy confirmed T cell non-Hodgkin lymphoma at two anatomical sites (bladder and stomach), which was subsequently treated. Molecular analysis of the T cell receptor (TCR) gamma chain gene rearrangements showed a distinct monoclonal T cell population in the bladder and gastric biopsies. The same analysis in the lymphocytic gastritis-like biopsy sample showed a monoclonal population with identical base pair size to that identified in the other specimens. This report highlights the importance of TCR gene rearrangement analysis in the diagnosis of unusual gastric inflammation, and the use of capillary electrophoresis based polymerase chain reaction in the follow up of lymphoproliferative disorders.

Antigens, CD↗
PubMed2004

Discovery of binding motif pairs from protein complex structural data and protein interaction sequence data.

Unravelling the underlying mechanisms of protein interactions requires knowledge about the interactions' binding sites. In this paper, we use a novel concept, binding motif pairs, to describe binding sites. A binding motif pair consists of two motifs each derived from one side of the binding protein sequences. The discovery is a directed approach that uses a combination of two data sources: 3-D structures of protein complexes and sequences of interacting proteins. We first extract maximal contact segment pairs from the protein complexes' structural data. We then use these segment pairs as templates to sub-group the interacting protein sequence dataset, and conduct an iterative refinement to derive significant binding motif pairs. This combination approach is efficient in handling large datasets of protein interactions. From a dataset of 78,390 protein interactions, we have discovered 896 significant binding motif pairs. The discovered motif pairs include many novel motif pairs as well as motifs that agree well with experimentally validated patterns in the literature.

Amino Acid Motifs↗
PubMed2004

Joint analysis of multiple cDNA microarray studies via multivariate mixed models applied to genetic improvement of beef cattle.

In functional genomic laboratories, it is common to use the same microarray slide across studies, each investigating a unique biological question, and each analyzed separately due to computational limitations and/or because there is no hybridization of samples from different studies on one slide. However, the question of analyzing data from multiple studies is a major current issue in microarray data analysis because there are gains to be made in the accuracy of estimated effects by exploiting a covariance structure between gene expression data across studies. We propose an approach for combining multiple studies using multivariate mixed models, with the assumption of a nonzero correlation among genes across experiments, while imposing a null residual covariance. We applied this method to jointly analyze three experiments in genetics of cattle with a total of 54 arrays, each with 19,200 spots and 7,638 elements. The resulting seven-variate model contains 752,476 equations and 56 covariances. To identify differentially expressed genes, we applied model-based clustering to a linear combination of the random gene x variety interaction effect. We enhanced the biological interpretation of the results by applying an iterative algorithm to identify the gene ontology classes that significantly changed in each experiment. We found 118 elements with coordinate expression that clustered into distinct biological functions such as adipogenesis and protein turnover. These results contribute to our understanding of the mechanistic processes involved in adipogenesis and nutrient partitioning.

Animals↗
PubMed2004

A case of nephrogenic fibrosing dermopathy.

INTRODUCTION: Nephrogenic fibrosing dermopathy is a recently recognised fibrosing disorder originally identified as a scleromyxoedema-like cutaneous disease in patients with renal disease. CLINICAL PICTURE: A 45-year-old lady with systemic lupus erythematosus presented with well-defined erythematous, non-tender, indurated plaques on both legs 4 months after haemodialysis for rapidly progressive glomerulonephritis and acute renal failure. Skin biopsy showed dermal fibrosis with increased proliferation of dermal fibroblasts and collagen bundles separated by clefts. There were increased dermal deposits of mucin and an increase in elastic fibres. TREATMENT AND OUTCOME: Haemodialysis was instituted for 2 weeks followed by monthly intravenous cyclophosphamide. Skin lesions remained unchanged 8 months later despite normalisation of renal function. CONCLUSION: Nephrogenic fibrosing dermopathy appears to be a definite new entity in patients with underlying renal insufficiency. Further multi-centre collaborative study is necessary to identify the prevalence, cause, treatment and prognosis of this disorder.

Acute Kidney Injury↗
PubMed2003

Quantitative three-dimensional anatomy of cervical, thoracic and lumbar vertebrae of Chinese Singaporeans.

This paper details the quantitative three-dimensional anatomy of cervical, thoracic and lumbar vertebrae (C3-T12) of Chinese Singaporean subjects based on 220 vertebrae from 10 cadavers. The purpose of the study was to measure the linear dimensions, angulations and areas of individual vertebra, and to compare the data with similar studies performed on Caucasian specimens. Measurements were taken with the aid of a three-dimensional digitiser. The means and standard errors for linear, angular and area dimensions of the vertebral body, spinal canal, pedicle, and spinous and transverse processes were obtained for each vertebra. Compared to the Caucasian data, all the dimensions were found to be smaller. Of significance were the spinal canal area, and pedicle width and length, which were smaller by 31.7%, 25.7% and 22.1% on average, respectively. A slight divergence, instead of convergence, was found from T8 to T12. According to the findings, the use of a transpedicle screw may not be feasible. The results can also provide more accurate modelling for analysis and design of spinal implants and instrumentations, and also allow more precise clinical diagnosis and management of the spine in Chinese Singaporeans.

Aged↗
PubMed2003

Early events of SARS coronavirus infection in vero cells.

An isolate from a patient in the recent severe acute respiratory syndrome (SARS) outbreak in Singapore was used to infect Vero E6 cells. This study concentrated on the first 30 min of infection. It was discovered that the SARS coronavirus attached, entered, and uncoated the nucleocapsids, all within a 30-min period. At 5 min after infection, several virus particles lined the Vero cell plasma membrane. Virus particles were at various stages of fusion at the cell surface, since entry was not a synchronised process. After entry (10 and 15 min), spherical core particles moved into the cytoplasm within large vacuoles. Quite surprising at such early stages of infection (20 min), a virus-induced change in the infected cells was evident. The induction of myelin-like membrane whorls was obvious within the same vacuoles as the core particles. The significance of this virus-induced change is unknown at this stage. By 25-30 min postinfection (p.i.), the spherical core particles appeared to be disassociating and, in their place, doughnut-shaped electron-dense structures were observed. These could be the virus genomes together with the helical nucleocapsids. They were no longer in large vacuoles but packaged into smaller vacuoles in the cytoplasm, and occasionally in small groups.

Animals↗