Biomedical subjects

T C Tan

Publications and source records attributed to T C Tan.

At least 19 recordsLinked to original sources

PubMed2006

Giant cavernous hemangiomas: report of three cases.

Giant cavernous hemangiomas occur very rarely, and little has been reported about their behavior. In this case report three cavernous hemangiomas with a diametric measure between 6 cm and 7 cm and distinct features will be described. A 36-year-old female patient presented with headache and nausea. A CT scan disclosed a large circumscribed tumor with strong contrast enhancement in the temporo-parieto-occipital region of the right cerebral hemisphere and extension into the right cerebellar hemisphere. A 35-year-old woman was admitted to our emergency ward with a generalized seizure and a dilated pupil. The CT scan showed an extensive left frontal lesion containing a substantial hyperintense part, suspicious for hemorrhage. A 3-year-old girl was admitted with generalized seizure and progressively declining consciousness. A large left frontotemporal paraventricular multi-cystic lesion was encountered on the CT scan. All three patients were operated on. Two recovered very well. In the case of the 3-year-old girl stable disease was reached. Giant cavernomas do not differ from average-sized cavernomas in clinical, surgical or histopathological presentation but may differ radiologically. However, the possible diagnosis of cavernoma can be overlooked, due to their size and possible differential diagnosis.

Adult↗

PubMed2006

Amoeboid form of Blastocystis hominis - a detailed ultrastructural insight.

The amoeboid form of Blastocystis hominis has been reported infrequently, and its morphological descriptions have yielded conflicting and confusing reports. In the present study, we used the amoeboid forms seen predominantly in symptomatic patients infected with Blastocystis to provide detailed descriptions on the fine surface structure and intracellular morphology. Scanning electron microscopy revealed the irregular shape of the amoeboid form, with an intercalated fibrillar structure and a highly convoluted surface with deep indentations and projected pseudopodia. Transmission electron microscopy showed the existence of two types of amoeboid forms of B. hominis in in vitro culture, one with a large central vacuole containing tiny electron-dense particles while the other contains multiple small vacuoles in the cytoplasm. A surface coat with varying thickness surrounded the amoeboid form, which also showed prominent, extended pseudopodia of varying shape. Irregularly shaped mitochondrion-like organelles with prominent cristae, lipid inclusions, and multiple vacuoles were frequently seen in close proximity with the pseudopodia. The characteristic nucleus with a crescentic band of electron-dense chromatin material was also seen.

Animals↗

PubMed2006

PCR fingerprinting of Blastocystis isolated from symptomatic and asymptomatic human hosts.

Genomic DNA from 16 Blastocystis hominis isolates comprising of eight asymptomatic isolates (A1-A8) and eight symptomatic isolates (S1-S8) was amplified by arbitrarily primed polymerase chain reaction (AP-PCR) using 38 arbitrary 10-mer primers. Six primers (A10, B5, C20, D1, F6, and F10) generated reproducible DNA fingerprints. AP-PCR amplification revealed similar DNA fingerprints among all symptomatic isolates (S1-S8) with common bands at 850 bp using primer A10, 920 bp using primer B5, and 1.3 kbp using primer D1. Isolates A1, A3, A4, A5, A6, and A7 showed similar DNA banding patterns and all asymptomatic isolates (A1-A8) shared a major band at 1 kbp using primer B5. Isolates A2 and A8 showed distinct DNA banding patterns that differed from the remainder of the isolates. The results of the phylogenetic analyses showed that all symptomatic isolates (S1-S8) formed a clade with >70% similarity among the isolates and which were clearly separate from asymptomatic isolates A1, A3, A4, A5, A6, and A7. Asymptomatic isolates A2 and A8 formed two distinct and separate clades. AP-PCR revealed higher genetic variability within the asymptomatic isolates than within the symptomatic isolates. The present study suggests that AP-PCR can be a valuable method for differentiating between isolates of B. hominis and our results support the hypothesis that our asymptomatic and symptomatic B. hominis isolates may represent two different strains/species with varying pathogenic potential.

Adolescent↗

PubMed2006

Tocolytic treatment for the management of preterm labour: a systematic review.

Spontaneous preterm labour and delivery accounts for approximately one-third of preterm births, which is the predominant cause of perinatal mortality and morbidity. This review aims to evaluate the evidence on the benefits and harms of five classes of tocolytic therapy, namely: betamimetics, calcium channel blockers, magnesium, non-steroidal anti-inflammatory agents, and atosiban. We performed a systematic review of the effectiveness of tocolytics to stop uterine contractions (first-line therapy). Reports of randomised controlled trials from searches of MEDLINE, bibliographies of review articles, Cochrane Collaboration and its Pregnancy and Childbirth Review Group between 1966 and 2003 were identified, using the search terms "randomised controlled trial" (RCT), "preterm labor", "tocolysis", "betamimetics", "ritodrine", "prostaglandin synthetase inhibitors", "indomethacin", "calcium channel blockers", "nifedipine", "oxytocin receptor blockers", "atosiban", and "magnesium sulphate". Studies on women with preterm labour comparing the effects of a tocolytic with a placebo or no treatment that met our inclusion criteria, were included. To our knowledge, the trials were conducted mainly before 1999 and there were no placebo-controlled trials after that. Of the 86 articles identified and evaluated, 14 first-line studies met more stringent requirements for meta-analyses. Tocolytics were associated with significant decreases in the odds of delivery within 24 hours (odds-ratio [OR] 0.54, 95 percent confidence interval [CI] 0.32-0.91) and 48 hours (OR 0.47, 95 percent CI 0.30-0.75). These effects were significant for beta-agonists, atosiban and indomethacin, but not magnesium sulphate. Maternal side-effects significantly associated with betamimetics were pulmonary oedema, cardiac arrhthymias and hypokalaemia. Although calcium antagonists have not been evaluated against placebo, comparative trials with beta-agonists have shown more favourable neonatal outcomes and better prolongation of gestation. In conclusion, the management of threatened preterm labour with first-line tocolytic therapy can prolong gestation. However, the time gained in-utero need to be optimised. There is no clear first-line tocolytic agent. The use of tocolytic agents should be individualised and based on maternal condition, potential side-effects and gestational age.

Female↗

PubMed2005

Predominance of amoeboid forms of Blastocystis hominis in isolates from symptomatic patients.

Blastocystis hominis is one of the most common human parasites that inhabit the intestinal tract. Conflicting reports continue to exist regarding the existence and the functional role of the amoeboid forms in the life cycle of the parasite. The present study investigates the presence of these forms in 20 isolates obtained from ten symptomatic and asymptomatic patients respectively. A total of 10,000 parasite cells per ml from each isolate were inoculated into three culture tubes each containing 3 ml of Jones' medium supplemented with 10% horse serum, incubated at 37 degrees C. The contents were examined daily for 10 days. Irregular and polymorphic amoeboid forms with multiple extended pseudopodia were observed in all isolates from symptomatic patients, while none of the isolates from asymptomatic patients showed the presence of the amoeboid forms. The amoeboid forms were initially noted on day 2 and the percentages increased from 2% to 28%, with peak percentages from day 3 to day 6. Transmission electron microscopy revealed two types of amoeboid forms; one containing a large central vacuole completely filled with tiny electron-dense granules, and the other which revealed multiple small vacuoles within the central body. The cytoplasm contained strands of electron-dense granules resembling rough endoplasmatic reticulum, which is suggestive of active protein synthesis. The surface coat of the amoeboid form surrounding the parasite showed uneven thickness. Acridine orange stained the central body yellow and the periphery orange, indicating activity at the level of nucleic acids. The amoeboid form could either be an indicator of pathogenicity of B. hominis, or the form likely to contribute to pathogenicity and be responsible for the symptoms seen in patients.

Adolescent↗

PubMed2005

Viable blastocystis cysts in Scottish and Malaysian sewage samples.

Blastocystis cysts were detected in 38% (47/123) (37 Scottish, 17 Malaysian) of sewage treatment works. Fifty percent of influents (29% Scottish, 76% Malaysian) and 28% of effluents (9% Scottish, 60% Malaysian) contained viable cysts. Viable cysts, discharged in effluent, provide further evidence for the potential for waterborne transmission of Blastocystis.

Animals↗

PubMed2005

Severe upper limb complications from parenteral abuse of Subutex.

INTRODUCTION: Subutex is a sublingual formulation of buprenorphine that is used to treat opioid dependency. It may be abused parenterally with disastrous consequences. CLINICAL PRESENTATION: We present 4 cases of parenteral abuse of Subutex resulting in severe upper limb complications. TREATMENT: Two vascular complications were treated with combinations of anticoagulants, vasodilators, brachial plexus bock and iloprostol. One severe hand abscess required surgical debridement, and 1 median nerve injury required neurolysis. OUTCOME: All patients had a poor outcome. Both patients with vascular complications required multiple amputations, the patient with a thenar abscess had severely impaired thumb function, and the patient with median nerve injury has ongoing neuralgic pain, numbness and thenar weakness. CONCLUSION: The incidence of complications of parenteral abuse of Subutex is increasing in Singapore. These complications have a poor outcome despite adequate management, and are best prevented by education or legal means.

Adult↗

PubMed2004

Epithelioid schwannoma of the vestibular nerve.

Epithelioid schwannomas are rarely encountered intracranially, with only four cases involving the eighth nerve reported in the literature. Histological behaviour ranging from benign to aggressive has been described. We report a 45-year-old woman who presented with right-sided tinnitus and hearing impairment. Magnetic resonance imaging revealed a tumour in the right cerebellopontine angle with intracanalicular extension. The patient underwent retromastoid craniectomy with near-total tumour excision. Microscopical examination confirmed the diagnosis of epithelioid schwannoma of the vestibular nerve. Intraoperative findings of sharp circumscription, bland histological appearance, low proliferative activity, coupled with the indolent clinical course, point to the quiescent nature of the lesion in this case.

Cranial Nerve Neoplasms↗

PubMed2003

Severe newborn encephalopathy unrelated to intrapartum hypoxic events: 3 case reports.

INTRODUCTION: Newborn encephalopathy is an important clinical problem associated with considerable morbidity and mortality and is pertinent in the assignment of blame in obstetrics litigation. CLINICAL PICTURE: We report 3 babies with severe neonatal encephalopathy. OUTCOME: In all 3 cases, intrapartum hypoxic insult was unlikely to be a significant contributing factor towards the development of neonatal encephalopathy. The aetiology was unclear in the first 2 cases and there was antecedent antenatal cause of feto-maternal haemorrhage in the last case. CONCLUSION: Prevention of neonatal encephalopathy was not possible in these 3 cases. We recommend that umbilical cord blood gases be clearly documented in such cases to reduce unnecessary obstetrics litigation of intrapartum asphyxia as the significant contributing factor to the poor neonatal outcome. Clinicians must have a high index of suspicion of antecedent causes and perform the necessary investigations to elucidate the aetiology of the neonatal encephalopathy.

Adult↗

PubMed2001

Protein phosphorylation is required for endocytosis in nerve terminals: potential role for the dephosphins dynamin I and synaptojanin, but not AP180 or amphiphysin.

Dynamin I and at least five other nerve terminal proteins, amphiphysins I and II, synaptojanin, epsin and eps15 (collectively called dephosphins), are coordinately dephosphorylated by calcineurin during endocytosis of synaptic vesicles. Here we have identified a new dephosphin, the essential endocytic protein AP180. Blocking dephosphorylation of the dephosphins is known to inhibit endocytosis, but the role of phosphorylation has not been determined. We show that the protein kinase C (PKC) antagonists Ro 31-8220 and Go 7874 block the rephosphorylation of dynamin I and synaptojanin that occurs during recovery from an initial depolarizing stimulus (S1). The rephosphorylation of AP180 and amphiphysins 1 and 2, however, were unaffected by Ro 31-8220. Although these dephosphins share a single phosphatase, different protein kinases phosphorylated them after nerve terminal stimulation. The inhibitors were used to selectively examine the role of dynamin I and/or synaptojanin phosphorylation in endocytosis. Ro 31-8220 and Go 7874 did not block the initial S1 cycle of endocytosis, but strongly inhibited endocytosis following a second stimulus (S2). Therefore, phosphorylation of a subset of dephosphins, which includes dynamin I and synaptojanin, is required for the next round of stimulated synaptic vesicle retrieval.

Adaptor Proteins, Vesicular Transport↗

PubMed2001

Traumatic intracranial aneurysm in infancy.

An anterior cerebral artery traumatic aneurysm in a 15-month-old infant is described. The diagnosis was confirmed by computed tomographic angiography. The patient recovered fully after successful clipping of the aneurysm. As the signs of traumatic intracranial aneurysm may be subtle especially in young children, a high degree of suspicion is essential in patients presenting with delayed neurological deterioration after head trauma.

Accidental Falls↗

PubMed2001

The contributions of Otfrid Foerster (1873-1941) to neurology and neurosurgery.

BEST REMEMBERED FOR his description of the dermatomes in man, Otfrid Foerster was also an adept neurosurgeon and an innovative experimental neurophysiologist. As a neurologist, his contributions included conceptualizing rhizotomy as a cure for spasticity, anterolateral cordotomy for pain, the hyperventilation test in epilepsy, Foerster's syndrome, and the first electrocorticogram of a brain tumor. As a neurosurgeon, Foerster was able to excise intraventricular, hypophyseal, and quadrigeminal lesions and to perform epilepsy surgery under primitive conditions without clips, diathermy, or suction. The results were good and reflected his consummate knowledge of neuroanatomy and neurophysiology. As an investigator, Foerster emphasized clinically orientated neurophysiology and was able to forge a link between his observations and proposed methods of treatment. A prolific writer, he published more than 300 scientific monographs encompassing every aspect of the nervous system, including tabes, movement disorders, spasticity, extrapyramidal diseases, dermatomes, epilepsy, cortical localization, brain tumors, peripheral nerve injuries, and pain. Foerster's superb command of languages led to his popularity as a speaker in Europe and North America. Students who flocked to learn from his encyclopedic knowledge and skill were privy to Foerster's legendary hospitality and charm. A man of delicate constitution, he was single-minded in his quest to unravel the mysteries of the nervous system. The inscription "Patriae scientiae inserviendo" or "In the service of science and Fatherland" was chosen by Foerster for his Institute of Neurology and is a fitting memorial to this neurosurgical giant.

Germany↗

PubMed2001

Subfrontal schwannoma masquerading as meningioma.

Intracranial schwannomas not associated with cranial nerves are rare and seldom encountered in the subfrontal region. We report a case of subfrontal schwannoma in a 21-year-old man who presented with seizures. Radiological features resembled an olfactory groove meningioma. The histological diagnosis of schwannoma was confirmed by immunohistochemical staining with S-100 and electron microscopy. We advocate the use of immunohistochemistry and electron microscopy as adjuncts to conventional light microscopy in differentiating schwannomas from meningiomas. Surgery remains the main therapeutic modality and complete excision is associated with cure.

Adult↗

PubMed1998

Elements in the hair of South-east Asian islanders.

Mercury (Hg), lead (Pb), cadmium (Cd) and copper (Cu) in hair samples from Singapore island (85 samples) and two islands off Batam, Indonesia (68 samples) were analysed to assess the environmental uptake of elements. Hair samples were washed with 0.1% Triton X-100 solution for 20 min in an ultrasonic bath, rinsed five times with de-ionized water and air dried. Ten to 20 mg of hair samples were digested with 1 ml of ultra-pure concentrated nitric acid in Parr bombs at 120 degrees C for 2 h. Hair digests were analysed by atomic absorption spectrophotometry (AAS). Hg was determined by the cold vapour AAS method and Pb, Cd and Cu by the electro-thermal graphite furnace AAS method. For Singapore hair, the contents of Cd (in microgram/g) averaged 0.17 (range 0.02-1.81); Cu 13.2 (range 3.1-70.1); Hg 5.92 (range 1.14-35.52); and Pb 6.74 (range 0.06-107.8). For the islands off Batam, Cd was 0.32 (range 0.06-1.80); Cu 21.1 (range 3.8-143.6); Hg 5.59 (range 0.78-60.86); and Pb 15.1 (range 0.13-116.6). Statistically significant differences in Cd, Pb and Hg contents were observed between the hair samples from Singapore and those of the islands off Batam in cumulative logit analysis. Hair from Singapore contained more Hg, but less Cd and Pb compared to hair from the islands off Batam. For Pb in hair, significant differences were also observed between the two islands off Batam (island 1, 18.9; and island 2, 10.2). These differences in hair metal contents are due to differences in community lifestyle (dietary, environmental or occupational intake).

Diet↗

PubMed1998

Diffuse cavernous hemangioma of the rectum complicated by invasion of pelvic structures. Report of two cases.

PURPOSE: We present two cases of diffuse cavernous hemangioma of the rectum that invaded the pelvic structures. METHODS: Two young women suffering from intermittent rectal bleeding were studied using computed tomography and magnetic resonance imaging. RESULTS: Beside the rectal hemangioma, computed tomography and magnetic resonance imaging revealed that the pelvic ureter and the iliac vessels were each eroded by the tumor that produced symptoms in these two patients. CONCLUSION: Computed tomography and magnetic resonance imaging permit direct visualization for tumor staging and also for recognition of any pelvic structure invasion, which facilitate preoperative assessment of diffuse cavernous hemangioma of the rectum.

Adult↗

PubMed1997

Tuberculoma of the liver presenting as a hyperechoic mass on ultrasound.

An unusual case of hepatic macronodular tuberculoma is presented. As demonstrated by CT, the tuberculoma replaced the entire lateral segment of the left lobe of liver and resembled an infiltrative tumour. On ultrasound, the tuberculoma presented as a hyperechoic lesion, in contrast to a round hypoechoic mass which is usually seen in this condition. Hepatic macronodular tuberculomas are not uncommonly misdiagnosed as primary or secondary liver tumours by imaging studies, and the definite diagnosis is usually established by liver biopsy. The prognosis of hepatic macronodular tuberculoma is usually very good with effective treatment.

Adult↗

PubMed1997

Cognitive testing of elderly Chinese from selected community clubs in Singapore.

The aim of this study was to describe the psychometric performance of cognitively normal elderly Chinese on selected psychological tests. One hundred and fifty-five community-living, cognitively intact elderly Chinese, stratified according to age and gender were administered a selected neuropsychological assessment battery which comprised the Abbreviated Mental Test (AMT), the Chinese Mini-Mental Status (CMMS), the Short Blessed Test (SBT), the Word-List Immediate Memory (WL-i), the Word-List Delayed Memory (WL-d), the Word-List Recognition Memory (WL-r), the Set Test (ST), the modified Boston Naming Test (BNT), the Constructional Praxis Test (CPT), the Block Design Test (BDT) and the Object Assembly Test (OAT). The local median scores (ranges) of the above tests were as follows-AMT: 9 (6-10); CMMS: 25 (16-28); SBT: 2 (0-10); WL-i: 17 (8-27); WL-d: 5 (0-10); WL-r: 9 (1-10); ST: 13 (6-25); BNT: 14 (10-15); CPT: 1 (0-3); BDT: 19 (0-42); OAT: 20 (3-33). These results can assist in the clinical identification of cognitive abnormalities amongst the elderly Chinese in Singapore. Future work will attempt to adjust these overall scores for variables such as the subjects' education and age.

Aged↗

PubMed1997

Functional status of the elderly in Singapore--the trend over a decade.

The study looks at the level and types of functional disabilities of a random sample of elderly individuals in the community through direct interviews using a questionnaire in 1992 and compares the results to that obtained from a similar study done in 1982. Two hundred and eighty-three elderly aged 60 years and above were studied. In the activities of daily living (ADL) functions category, most elderly individuals were independent in dressing (96.1%), bathing (95.4%), preparing meals (92.6%) and using the toilet (89.4%). There was increasing disabilities in the instrumental activities of daily living (IADL) functions, in ascending order of difficulty--light chores (81.3% independent), shopping (67.8% independent) and heavy chores (60.1% independent). Eight (2.8%) of the elderly were confined to bed most of the time. Comparing the results with the 1982 cohort, the 1992 cohort was more dependent, with significant increase in difficulty with dressing, using the toilet, bathing, and higher functional activities. There was also significant increase in the number of elderly confined to bed most of the time, from 1% to 2.8%. The only activity that showed a reverse trend was food preparation. The trend of dependence among the elderly is growing and deserves further specific studies to examine the possible reasons for the increasing disabilities in the elderly population, especially as the population is ageing rapidly.

Activities of Daily Living↗