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Biomedical subjects

S H Tan

Publications and source records attributed to S H Tan.

At least 37 records · Page 2Linked to original sources
PubMed2003

Cutaneous lymphomas other than mycosis fungoides in Singapore: a clinicopathological analysis using recent classification systems.

BACKGROUND: Cutaneous lymphomas other than mycosis fungoides (MF) are a heterogeneous group with wide variations in clinical presentation, biological behaviour and prognosis. New classification systems have been designed or proposed in recent years, with well-defined disease entities and emphasis on the importance of site. OBJECTIVES: This study aims to analyse a series of non-MF lymphomas in an institution-based dermatological setting in Singapore, based on the European Organization for Research and Treatment of Cancer (EORTC) classification and the World Health Organization (WHO) classification. A secondary objective is to highlight the clinical utility of both classification systems. PATIENTS AND METHODS: Forty cases diagnosed over a 12-year period were examined by immunohistochemistry with antibodies targeting CD3, CD4, CD5, CD8, CD20, CD30, CD43, CD45RO, CD56 and CD68 in paraffin-embedded specimens. The immunohistological diagnosis was correlated with the clinical presentation and staging investigations for the final diagnosis and the course of disease recorded. RESULTS: Non-MF T-cell lymphomas presenting in the skin comprised 31 cases (78%) and were 3(1/2) times more common than B-cell lymphomas, which comprised nine cases (22%). The common subtypes were lymphomatoid papulosis, CD30+ large cell cutaneous T-cell lymphoma and subcutaneous panniculitis-like T-cell lymphoma. The commonly ascribed B-cell pattern with infiltrates in the mid and deep dermis and perivascular spaces was seen in 60% of T-cell lymphomas. Overall, there were equal numbers of primary cutaneous T-cell lymphomas and those due to concurrent or secondary cutaneous lymphoma. Five of six cases of subcutaneous panniculitis-like T-cell lymphoma had concurrent cutaneous and systemic involvement and their median survival was 7 months. CONCLUSIONS: The predominance of cutaneous T-cell lymphomas in this case series closely matched that reported from east Asia; cutaneous B-cell lymphomas are much less common than in Europe. The EORTC classification, which is designed only for primary cutaneous lymphomas, should be used in conjunction with the WHO classification because of the high prevalence of cutaneous lymphomas as the secondary site of disease from systemic lymphoma. In addition, subcutaneous panniculitis-like T-cell lymphoma is a primary cutaneous lymphoma where systemic involvement is common at initial presentation. We propose full immunophenotyping and complete clinical evaluation with staging investigations for all patients presenting with cutaneous lymphomas other than MF.

Adolescent↗
PubMed2003

Anterior subfascial transposition of the ulnar nerve.

After anterior subfascial transposition, the ulnar nerve lies superficial to the flexor-pronator muscle group but deep to its fascia. Eight patients with cubital tunnel syndrome were treated with this method and reviewed retrospectively. The average age at the time of operation was 52 years. All patients had severe cubital tunnel syndrome based on Dellon's classification. The average follow-up period was 2 years and 9 months. Post-operative outcome assessment was based on the modified Bishop rating system. Six patients had excellent and two had good outcomes. All were back at work by the 5th post-operative week. There were no complications or recurrence of symptoms. Anterior subfascial transposition of the ulnar nerve is an effective method of surgical treatment for patients with severe cubital tunnel syndrome.

Adult↗
PubMed2003

Heterodigital arterialized flaps for large finger wounds: results and indications.

Deep defects of the hand and fingers with an unhealthy bed exposing denuded tendon, bone, joint, or neurovascular structures require flap coverage. However, the location and size of the defects often preclude the use of local flap coverage. Free-flap coverage is often not desirable either, because the recipient vessels may be unhealthy from surrounding infection or trauma. In such situations, a regional pedicled flap is preferable. A solution to this is the heterodigital arterialized flap. This flap is supplied by the digital artery and a dorsal vein of the finger for venous drainage. Unlike the neurovascular island flap, the digital nerve is left in situ in the donor finger, thus avoiding many of the neurologic complications associated with the Littler flap. The digital artery island flap is centered on the midlateral line of the donor finger. It extends from the middorsal line to the midpalmar line. The maximal length of the flap is from the base of the finger to the distal interphalangeal joint. By preserving the pulp and the digital nerve, a sensate pulp on the donor finger remains that reduces donor-finger morbidity and also preserves fingertip cosmesis. Twenty-nine flaps were performed in 29 patients and the outcomes in the donor finger and the reconstructed finger were reviewed. The flap survival was 100 percent. There were no cases of flap ischemia or flap congestion. Good venous drainage of the flap through the additional dorsal vein was helpful in preventing the occurrence of early postoperative venous congestion, which is common in island flaps of the fingers, which depend on only the venae comitantes for drainage. Donor-finger morbidity, measured in terms of range of motion and two-point discrimination in the pulp, was minimal. Ninety-seven percent of the donor fingers achieved excellent or good total active motion according to the criteria of Strickland and Glogovac. Pulp sensation in the donor fingers was normal in 28 of the 29 donor fingers. No cold intolerance of the donor finger or the adjacent finger is reported in this series.

Adolescent↗
PubMed2003

Sweet's syndrome associated with Mycobacterium chelonae and herpes simplex virus infections: a case report.

INTRODUCTION: We report a case of Sweet's syndrome associated with Mycobacterium chelonae and herpes simplex virus infection. CLINICAL PICTURE: A 56-year-old Chinese woman presented with a granulomatous subglottic mass and right lung nodules, which responded to a 9-month course of anti-tuberculous treatment. Subsequently, she developed genital herpes simplex virus infection, which was followed by a cutaneous eruption with vesicular plaques associated with fever, bilateral cervical lymph nodes and neutrophilia. Mycobacterium chelonae was isolated from lymph node cultures. The cutaneous presentation of Sweet's syndrome was confirmed on skin biopsy. There was no evidence of underlying immunosuppression, malignancy or connective tissue disease. TREATMENT: She was treated with rifampicin, clarithromycin and oral prednisolone. OUTCOME: There was complete resolution of her cutaneous lesions and cervical lymphadenopathy. CONCLUSION: The association between Sweet's syndrome and Mycobacterium chelonae as well as herpes simplex virus, though rare, should be considered in all patients presenting with Sweet's syndrome.

Female↗
PubMed2003

Clinical profile and treatment outcome of livedoid vasculitis: a case series.

INTRODUCTION: Livedoid vasculitis is a painful ulcerative condition affecting the legs that is often difficult to treat. In this case series, the clinical profile of 6 patients with livedoid vasculitis and their treatment response to aspirin and pentoxifylline are reported. MATERIALS AND METHODS: This is an open trial. Investigations to exclude secondary causes of livedoid vasculitis were done. Skin biopsies were performed for histology and direct immunofluorescence. Four patients were treated with pentoxifylline and 2 with aspirin. Response to treatment was assessed at the third and sixth weeks. Thereafter, treatment was individualised according to each patient's clinical response. RESULTS: Only 1 out of 6 patients had a good response. This patient was treated with pentoxifylline. Most patients required treatment with drugs such as prednisolone, colchicine and azathioprine to control disease activity after the trial period. CONCLUSION: Pentoxifylline or aspirin did not result in significant improvement for most of our patients when used alone. Combination with immunosuppressive treatment yielded better results.

Adult↗
PubMed2002

The cloning of Ty1-copia-like retrotransposons from 10 varieties of banana (Musa Sp.).

Ty1-copia-like retrotransposons have been identified and investigated in several plant species. Here, the internal region of the reverse transcriptase (RT) gene of Ty1-copia-like retrotransposons was amplified by PCR from total genomic DNA of 10 varieties of banana. Two to four clones from each variety were sequenced. Extreme heterogeneity in the sequences of Ty1-copia-like retrotransposons from all the varieties was revealed following sequence analysis of the reverse transcriptase (RT) fragments. The size of the individual RT gene fragments varied between 213 and 309 bp. Southern blots of genomic DNA digested from Musa acuminata and other banana varieties probed with W8 clone from M. acuminata and A4 clone from Pisang Abu Nipah showed similar strong, multiple restriction fragments together with other faint hybridization band patterns with variable intensities indicating the presence of many copies of the Ty1-copia-like retrotransposons in the genomes. There was no correlation between retroelement sequence and the banana species (with A or B genomes) from which it arose, suggesting that the probes are not useful for tracking genomes through breeding populations.

Base Sequence↗
PubMed2002

Isolation and characterization of cDNA clones encoding ADP-glucose pyrophosphorylase from sago palm (Metroxylon sagu).

Four ADP-glucose pyrophosphorylase cDNA clones were isolated from mature leaves and pith of sago palm by the polymerase chain reaction (PCR) technique. Three of them (agpp10, agpp12 and agpl19) encoded the AGP large subunit, while the fourth clone (agpl1) encoded the small subunit. agpp10 and agpp12 were isolated from pith, agpl19 was isolated from mature leaves, while agpl1 from both tissues. In addition, a full-length cDNA of agpl1 was successfully isolated from a cDNA library of mature leaves by a PCR-based screening technique. Semi-quantitative analysis suggests that agpp10 and agpp12 were detectable only in pith, agpl19 only in leaves, while agpl1 was expressed in both leaves and pith tissues.

Amino Acid Sequence↗
PubMed2001

Quantitative three-dimensional anatomy of lumbar vertebrae in Singaporean Asians.

This paper details the quantitative three-dimensional anatomy of lumbar vertebrae L1-L5 from Asian (Singaporean) subjects based on 60 lumbar vertebrae from 12 cadavers. The purpose of the study was to measure the dimensions of the various parameters of the lumbar vertebrae and thereafter to compare the data with a study 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 lumbar vertebra. From this comparison, it was found that the dimensions of the vertebral body of the Asian subjects are slightly larger, with a maximum average difference of 8% for the posterior vertebral body height. The dimensions of the spinal canal, pedicle, and spinous and transverse processes of Asian subjects are smaller. The greatest difference can be found in the spinal canal area and pedicle width, which are smaller by an average of 30% and 20%, respectively. With the exception of the spinal canal depth, spinal canal area and pedicle width, all other parameters compared show a similar trend. The findings can provide more accurate modelling for analysis and spinal implant design and also allow more precise clinical diagnosis in sub-Asian groups.

Aged↗
PubMed2001

Recurrent nasopharyngeal carcinoma presenting as diffuse dermal lymphatic infiltration in the neck: three case reports.

BACKGROUND: Any malignancy has the propensity to metastasize to skin. The frequency of skin metastases vary in different tumors and occur in about 0.7% to 10% of all patients diagnosed with cancer. It is rare in nasopharyngeal carcinoma. METHOD: Three cases of relapsed nasopharyngeal carcinoma with diffuse dermal involvement were described. Their clinical presentation, results of investigations, and response to treatment were reviewed. Literature review of similar forms of presentation was done by means of a MEDLINE search. RESULTS: At the time of dermal relapse, all three patients had a uniform clinical picture of facial, periorbital, and lip swelling associated with stridor and dysphagia. Histologic findings showed dermal infiltrates of malignant cells, and CT scan showed diffuse infiltration of the subcutaneous tissue. Despite chemotherapy, the clinical course was relentless. CONCLUSION: This report describes a presentation of disease that is underdiagnosed and heightens awareness of oncologists to this form of recurrence in nasopharyngeal carcinoma.

Adult↗
PubMed2001

Transport and budding at two distinct sites of visible nucleocapsids of West Nile (Sarafend) virus.

It has been difficult to detect and visualize the physical nucleocapsid particles during the replication process of the flaviviruses. The use of cryo-immunoelectron microscopy has clearly revealed the capsid proteins and nucleocapsid particles of West Nile (Sarafend) virus (a flavivirus) for the first time. Physical nucleocapsid particles accumulated in large numbers from 8 hr postinfection. Double immunolabeling of the envelope and capsid proteins showed a close association of these structural proteins for most of the replication cycle. By 10 hr postinfection, budding of nucelocapsids from the plasma membrane was very obvious. Although maturation at the plasma membrane was the dominant mode, during late infection, intracellular maturation into large vacuoles was also observed.

Animals↗
PubMed2001

Hypertensive basal ganglia hemorrhage: a prospective study comparing surgical and nonsurgical management.

BACKGROUND: The optimal treatment of hypertensive supratentorial intracerebral hemorrhage is still debated. Some studies have shown no improvement in survival or functional outcome after surgery when compared to conservative management while others have shown otherwise. METHODS: This study was a prospective trial, matching patients for hematoma volume and Glasgow Coma score on admission. RESULTS: There were a total of 34 patients. Seventeen were treated conservatively and 17 surgically. There was no significant difference between the two groups in terms of age, GCS, hematoma volume, or presence of intraventricular blood. At 3, 6, and 12-month follow-up, they were assessed using the Modified Barthel Index by a blinded observer. There was no difference between the two groups at 3, 6, or 12 months follow-up. The mortality rate was similar in the two groups. CONCLUSIONS: Based on this study and review of the literature, we cannot recommend routine evacuation of clots to treat these hemorrhages.

Adult↗
PubMed2001

Late-onset hydroa vacciniforme: two case reports.

Hydroa vacciniforme (HV) is a rare blistering photodermatosis that heals with vacciniform scarring, with onset usually in childhood and spontaneous resolution by early adulthood. We report two cases of HV seen at the National Skin Centre, Singapore, both with a late onset at 20 years of age, during compulsory military service, and one with a less typical non-vesicular presentation, that initially caused some diagnostic difficulties.

Adult↗
PubMed2001

Pemphigus vulgaris following varicella infection.

We describe a 26-year-old Indian man who presented with chickenpox and subsequently developed pemphigus vulgaris 17 days after initial resolution of lesions. The mechanism of progression from one disease to the other is postulated to be that of epitope spreading or molecular mimicry.

Adult↗
PubMed2001

Chemical degradation of composite restoratives.

The chemical environment is one aspect of the oral environment, which could have an appreciable influence on the in vivo degradation of composite restoratives. The effects of chemical media on surface hardness of four composite restoratives (Silux [SX], Z100 [ZO], Ariston [AR] and Surefil [SF]) were investigated. The relationship between hardness and the thickness of the degradation layer was also studied. Thirty six specimens (3 x 4 x 2 mm) were made for each material. Following polymerization, the specimens were stored in artificial saliva at 37 degrees C for 24 h. The specimens were then randomly divided into six groups of six, subjected to microhardness testing (load = 500 gf, dwell time = 15 s) and stored in the following chemicals for 1 week at 37 degrees C: artificial saliva (S), distilled water (W), 0.02 N citric acid (C), 0.02 N lactic acid (L), heptane (H) and 75-25% ethanol-water solution (E). After conditioning, the specimens were again subjected to hardness testing and sectioned. Change in hardness (DH) was computed and the thickness of the degradation layer (DL) was measured using a computerized image analysis system at 600x magnification. Results of statistical analysis (ANOVA/Scheffe's [P < 0.05]) of DH based on materials were as follows: SX - E > all other mediums; ZO - W > C; and AR - S, W, E > H (> indicates significantly greater hardness change). No significant difference in DH was observed between the different chemicals for SF. The effects of chemical media on DH were found to be material dependent. A significant but weak positive correlation (Pearson's correlation [P < 0.05]) exists between change in hardness and thickness of the degradation layer.

Analysis of Variance↗
PubMed2001

Spindle cell variant of epithelioid sarcoma: an easily misdiagnosed tumour.

Epithelioid sarcoma is a histologically distinct soft tissue sarcoma of high grade malignancy. We report a case of epithelioid sarcoma in a young man who presented with multiple nodules over the left forearm, with bony invasion and pulmonary metastases. The histological features of the dermal tumour were those of a malignant spindle cell tumour with positive cytokeratin and vimentin staining and differed from the classical epithelioid sarcoma in its absence of typical necrobiotic nodular epithelioid pattern. It was the clinical presentation and the histology of the subcutaneous nodules that led to the final diagnosis of epithelioid sarcoma. This case illustrates a predominance of spindle cell pattern in the dermal tumour of epithelioid sarcoma, which has previously been reported as fibroma-like variant of epithelioid sarcoma.

Adult↗
PubMed2001

Comparative study of pemphigus vulgaris and pemphigus foliaceus in Singapore.

This is a retrospective study of all patients diagnosed to have pemphigus in our centre over a 3 year period. The case records of all patients with pemphigus from January 1995 to December 1997 were analysed. Fifty patients were diagnosed to have pemphigus during the study period. The diagnoses were pemphigus vulgaris in 31 patients, pemphigus foliaceus in 16, paraneoplastic pemphigus in two and IgA pemphigus in one. The average titre of anti-intercellular antibodies in patients with pemphigus vulgaris (1:96) was higher than the titre in patients with pemphigus foliaceus (1:69). The average initial dose of prednisolone required for disease control in patients with pemphigus vulgaris (62 mg/day) was significantly higher than that required for patients with pemphigus foliaceus (44 mg/day). In our study population, pemphigus vulgaris is a more severe and chronic disease than pemphigus foliaceus, as reflected in the higher titre of anti-intercellular antibodies, higher dose of systemic corticosteroids required for control of the disease, the longer duration to achieve complete remission and longer follow-up period.

Adult↗