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Biomedical subjects

C T Tan

Publications and source records attributed to C T Tan.

At least 55 records · Page 3Linked to original sources
PubMed2000

High mortality in Nipah encephalitis is associated with presence of virus in cerebrospinal fluid.

During the outbreak of Nipah virus encephalitis in Malaysia, stored cerebrospinal fluid (CSF) samples from 84 patients (27 fatal and 57 nonfatal cases) were cultured for the virus. The virus was isolated from 17 fatal cases and 1 nonfatal case. There were significant associations between CSF virus isolation and mortality as well as clinical features associated with poor prognosis. In addition, there was a positive linear correlation of CSF virus isolation with age. There was no significant association between CSF virus isolation and the character of the CSF, presence of Nipah-specific antibody in the serum or CSF, duration of illness before collection of samples, or sex or ethnicity of the patients. This study suggests that high viral replication in the central nervous system may be an important factor for high mortality.

Adolescent↗
PubMed1999

Fatal encephalitis due to Nipah virus among pig-farmers in Malaysia.

BACKGROUND: Between February and April, 1999, an outbreak of viral encephalitis occurred among pig-farmers in Malaysia. We report findings for the first three patients who died. METHODS: Samples of tissue were taken at necropsy. Blood and cerebrospinal-fluid (CSF) samples taken before death were cultured for viruses, and tested for antibodies to viruses. FINDINGS: The three pig-farmers presented with fever, headache, and altered level of consciousness. Myoclonus was present in two patients. There were signs of brainstem dysfunction with hypertension and tachycardia. Rapid deterioration led to irreversible hypotension and death. A virus causing syncytial formation of vero cells was cultured from the CSF of two patients after 5 days; the virus stained positively with antibodies against Hendra virus by indirect immunofluorescence. IgM capture ELISA showed that all three patients had IgM antibodies in CSF against Hendra viral antigens. Necropsy showed widespread microinfarction in the central nervous system and other organs resulting from vasculitis-induced thrombosis. There was no clinical evidence of pulmonary involvement. Inclusion bodies likely to be of viral origin were noted in neurons near vasculitic blood vessels. INTERPRETATION: The causative agent was a previously undescribed paramyxovirus related to the Hendra virus. Close contact with infected pigs may be the source of the viral transmission. Clinically and epidemiologically the infection is distinct from infection by the Hendra virus. We propose that this Hendra-like virus was the cause of the outbreak of encephalitis in Malaysia.

Adult↗
PubMed1999

A study of newly diagnosed epilepsy in Malaysia.

BACKGROUND/AIM OF STUDY: To determine the characteristics of newly diagnosed epilepsy in the multiracial population of Malaysia. METHODS: This is a prospective study of 165 consecutive newly diagnosed cases of epilepsy presenting to the neurology laboratory of the University Hospital, Kuala Lumpur. The inclusion criteria were: two or more seizures with interval of > 24 hours, age > 1 month, residents of Klang Valley. All the patients underwent an awake and sleep EEG. RESULTS: One hundred and sixty-five cases were collected over 1992-1994. Their ethnic origin was: Chinese (36%), Indian (35%), Malay (29%). The mean age of onset of epilepsy was 18.7 years. Localisation related epilepsies accounted for 57.6% of cases while the remaining 42.4% were generalised epilepsies. Of the generalised epilepsies, subclassification was as follows: idiopathic generalised epilepsy 28.5%, juvenile myoclonic epilepsy 5.5%, childhood absence epilepsy 3.6%, West syndrome 3%, Lennox Gastaut syndrome 1.2% and photosensitive epilepsy 0.6%. Twenty-two percent of the cases were symptomatic and 78% were cryptogenic/idiopathic. The patients had a mean of 3.9 other siblings. Only 0.76% of the close relatives (parents and siblings) had a history of epilepsy. CONCLUSION: The characteristics of epilepsy in Malaysia is largely similar to those reported elsewhere. Genetic factors may be playing a relatively minor role in causing epilepsy in this community.

Adolescent↗
PubMed1999

Use of titanium prosthesis to bridge a vertebral gap in the spine--a preliminary experimental study.

Resection of a vertebral body for spine tumour or fracture results in a vertebral gap which has to be bridged by autogenous graft, allograft, bone cement or metal spacer. Recently, there have been several metal spacers in the market. We have designed a titanium vertebral spacer which is extensible by way of a threaded mechanism. Coating with hydroxyapatite enables bone ingrowth onto the surface of the titanium spacer. Biomechanical analysis, using the Instron biaxial electro-servohydraulic testing machine, showed that the segment bridging the spacer was rigid and stiffer than the adjacent vertebral body motion segment. Histological study showed that there was bone growth across the vertebral gap indicating fusion had taken place.

Animals↗
PubMed1998

Inflammatory mediators and otitis media with effusion. An experimental approach using cell culture.

Otitis media with effusion is characterized by the presence of an inflammatory cellular infiltrate of the submucosa and a poor ventilation of the middle ear. This result in hypersecretion of mucus and alteration of the mucociliary clearance, which produce accumulation of fluid and cellular debris in the middle ear. The aim of this work was to investigate whether inflammatory mediators such as prostaglandins and oxygen metabolites modulate the absorptive function of the middle ear epithelium. The data we present demonstrated that: (i) among prostanoids, only prostaglandin E2 modulated the rate of sodium transport; (ii) oxidants had a stimulatory effect on ion transport; (iii) the role of reactive oxygen species was mediated by prostaglandin E2. This process might be involved in the impairment of the mucociliary clearance.

Absorption↗
PubMed1998

Cryptococcosis at the University Hospital, Kuala Lumpur.

We review our experience with 27 cases of pulmonary and meningeal cryptococcosis at the University Hospital, (Kuala Lumpar, Malaysia) where this is the most common cause of adult meningitis in patients without debilitating illnesses. Of the 27 cases analysed, six presented primarily with pulmonary symptomatology which usually were mainly cough, chest pain and low grade fever. The rest presented with primarily central nervous system (CNS) symptomatology of which headaches and fever were the most consistent symptoms although a third of these patients also had pulmonary lesions noted on chest radiographs. Treatment in all cases was with amphotericin B and 5-fluorocytosine and usually till a total cumulative dose of 1.5 g of amphotericin had been reached (an average of 10 weeks). Primary pulmonary presentations, if symptomatic, were treated as per CNS cryptococcosis due to the high likelihood of CNS dissemination. Incidental pulmonary cryptococcoma found on routine chest radiographs were confirmed by biopsy under ultrasound or fluoroscopy guidance and booked for surgical resection. Death usually occurred early in patients who presented late. Once patients responded to therapy, mortality was usually avoided. The only cause of morbidity in survivors was visual impairment or blindness, and this was attributed mainly to intracranial hypertension with residual deficits determined by the measures taken to lower intracranial pressures. Our experience suggests that: (i) symptomatic patients should have combination therapy with 5-fluorocytosine and amphotericin B till at least a cumulative dose of 1.5 g amphotericin B is reached irrespective of whether they have primary CNS or pulmonary symptomatology; (ii) non-symptomatic pulmonary cryptococcoma could be treated primarily by surgical resection; (iii) visual failure or papilloedema should be treated aggressively; and (iv) prognosis is good with adequate therapy and early presentation.

Adolescent↗
PubMed1998

Ion transports in the middle ear epithelium.

Ion transports in the middle ear epithelium have been recently characterized. Experimental data using cell culture have found the existence of a sodium transepithelial transport that drives a water flow. This is thought to play a key role in the maintain of air-filled and fluid-free cavities. Impairment of this process is involved in the pathogenesis of secretory otitis media, which is the main cause of acquired hearing loss. Several modulations of this transport have been evidenced: (i) reactive oxygen species induced an endogenous synthesis of prostaglandin E2 (PGE2), which in turn increased the cAMP level and modulated ion transport rate; (ii) steroids increased the expression of the alpha subunit sodium channel mRNA, which changes paralleled the modulation of ion transport in the middle ear epithelium; (iii) moderate hypoxia selectively and reversibly decreased the rate of sodium transport, as a result of a parallel decrease in alpha epithelial sodium channel subunit mRNA level. These modulations may explain the course of middle ear pathology. However, the development of an in vivo model has become mandatory to assess the relevance of these data in the pathophysiology of the middle ear.

Adrenal Cortex Hormones↗
PubMed1997

Glucocorticosteroids increase sodium transport in middle ear epithelium.

The effect of glucocorticosteroids on ion transport was investigated on a middle ear cell line with the short-circuit current (Isc) technique. Dexamethasone (DXM) produced a dose- and time-dependent increase in Isc. Concentration of half-maximal stimulation was 2.68 x 10(-8) M. This effect was blunted by the glucocorticoid antagonist RU-38486 and was related to Na+ transport, as evidenced by the inhibition induced by 1) apical addition of the Na+ channel inhibitor benzamil (10(-6) M) or 2) substitution of Na+ with N-methylglucamine in the incubation medium. The increase in Na+ transport resulted from a primary modulation of apical Na+ entry, since 1) the Na(+)-K(+)-ATPase activity of cellular homogenates was not modified by corticosteroids and 2) the DXM-induced increase in the ouabain-sensitive uptake of 86Rb was blunted by benzamil. Ribonuclease protection assay revealed 1) a constitutive expression of the mRNA encoding the alpha-subunit of the epithelial Na+ channel and 2) that DXM increased the expression of this transcript. This increase was dose dependent and paralleled changes in transepithelial Na+ transport. This study suggests that a component of the beneficial effect of steroid therapy for the treatment of otitis media might be related to increased fluid clearance.

Adenosine Triphosphate↗
PubMed1997

Systemic lupus erythematosus in Malaysia: a study of 539 patients and comparison of prevalence and disease expression in different racial and gender groups.

The aims of this study were to examine the clinical and laboratory features of Malaysian patients with systemic lupus erythematosus (SLE) and to identify any difference in disease expression between the different genders and among the three major ethnic groups of Malaysia. Retrospective analysis of all patients with SLE admitted to and followed-up at University Hospital Kuala Lumpur from 1974-90 was undertaken. Ethnic Chinese had the highest prevalence of SLE compared to other ethnic groups. There was a high incidence of renal disease, 74% of patient had significant proteinuria and half of these had associated nephrotic syndrome. Indian patients had significantly less incidence of skin manifestation compared to other racial groups. No difference in disease expression was detected between the ethnic Chinese and Indians and between the male and female patients. The overall 5 y and 10 y survival rates were 82% and 70% respectively. Indian patients had the poorest survival rates. Survival rates are similar among the Chinese and Malay patients. Our findings are in broad agreement with those previously reported.

Adolescent↗
PubMed1997

Modulation of middle ear epithelial function by steroids: clinical relevance.

The efficacy of steroid therapy for the treatment of otitis media in children remains controversial, and a putative modulation of the middle ear epithelial function has to be demonstrated. Using the MESV cell line, short-circuit current (ISC) technique was used to evaluate changes in ion transport induced by glucocorticoids. Dexamethasone (DXM) produced a dose- and time-dependent increase in ISC in MESV cells. This effect was inhibited by specific glucocorticoid antagonist (RU-38486) and was related to a sodium transport, since the DXM-induced increase in ISC could be prevented or abolished i) by apical addition of the specific Na+ channel inhibitor benzamil; or ii) by substitution of sodium with N-Methyl-glucamine in the incubation medium. RNase protection assay revealed that DXM increased the expression of the alpha subunit sodium channel mRNA, which changes paralleled the modulation of ion transport. These data demonstrate that steroids up-regulate the trans-epithelial sodium transport in the middle ear epithelium. As far as these experimental data can be extrapolated to the in vivo situation, a component of the beneficial effect of steroid therapy for the treatment of otitis media may result from a corticosteroid-induced improvement in fluid clearance from the middle ear.

Amiloride↗
PubMed1996

Arabidopsis profilins are functionally similar to yeast profilins: identification of a vascular bundle-specific profilin and a pollen-specific profilin.

Four members of the Arabidopsis profilin (pfn) multigene family have been cloned, sequenced and analyzed. By RNA gel blot analysis it has been shown that these four genes fall into two groups: one group (pfn1 and pfn2) is expressed in all organs of the plant and the other group (pfn3 and pfn4) in floral tissues only. Based on amino acid sequence alignment Arabidopsis profilins can be divided into the same two groups: PFN1 and PFN2 are 89% identical and PFN3 and PFN4 are 91% identical. Between these two groups they are 71-75% identical. The Arabidopsis profilins bind poly-L-proline and can complement both the Saccharomyces cerevisiae profilin deletion mutant and the Schizosaccharomyces pombe cdc3-124/profilin mutation, showing that the plant profilins are functionally similar to yeast profilins despite the low amino acid sequence homology. Analysis of pfn promoter-GUS fusion genes in transgenic Arabidopsis shows that pfn2 is specifically expressed in the vascular bundles of roots, hypocotyls, cotyledons, leaves, sepals, petals, stamen filaments and stalks of developing seeds, whereas expression of pfn4 is restricted to mature and germinating pollen grains.

Amino Acid Sequence↗
PubMed1996

A community-based prevalence study on headache in Malaysia.

This community study on headache in Malaysia was based on IHS diagnostic criteria and showed the last-year prevalence of migraine was 9.0%. Migraine with aura accounted for only 10.6% of the migrainous population. The last-year prevalence of tension headache was 26.5% (94.4% episodic, 5.6% chronic) and 28.2% for other types of headache. No case of cluster headache was found. Almost two thirds of the migraine subjects graded their headaches as severe, while almost 60% of the tension headache subjects and almost 70% of the other headache subjects graded their headaches as mild. Overall, there was higher prevalence in females for migraine and tension headache, and in males for the other types of headache. The prevalence of headache was lower among those younger than 15 and older than 65 years of age. No significant differences were found in the prevalence of headache among the different racial groups nor among the urban versus the rural population. All the headache types shared the same triggering factors suggesting that different physiological characteristics are responsible for the type of pain suffered. In the location of this community with its tropical climate, headache was attributed to sun exposure in 51.9% of the migraine subjects, 55.7% of the tension headache subjects, and 36.6% of the group with other headaches.

Adolescent↗
PubMed1996

Road traffic accidents in patients with obstructive sleep apnoea.

Three patients involved in road traffic accidents were suspected to have obstructive sleep apnoea (OSA). Two of them fell asleep while riding motorcycles and one patient fell asleep behind the wheel of a truck causing it to overturn. The diagnosis of OSA in each case was suspected based on a history of loud snoring, restless sleep, and excessive daytime somnolence and was confirmed by sleep studies.

Accidents, Traffic↗
PubMed1996

Spinal dural arteriovenous malformation: a cause of myelopathy.

Spinal vascular malformation is an uncommon but potentially treatable cause of myelopathy. We describe two cases of angiographically proven spinal vascular malformation in Malaysia. The first case is a 47-year-old man who had a progressive myelopathy and the second a 60-year-old man with intermittent attacks of transient paraparesis leading to paraplegia. As the clinical presentation of spinal vascular malformation is variable, it should be considered as a cause of patients with myelopathy.

Angiography↗
PubMed1996

Traumatic luxation of the stapes evidenced by high-resolution CT.

We encountered a case of acquired perilymphatic fistula in which the origin of the disease, namely, the stapes begin medially displaced into the vestibule, was shown by thin-section CT. Accordingly, we recommend that every patient with suspected perilymphatic fistula of traumatic origin undergo high-resolution CT of the petrous bone.

Female↗
PubMed1995

Incidence of second cancers in patients treated for Hodgkin's disease.

BACKGROUND: Numerous studies of treatment for Hodgkin's disease have demonstrated large increases in the incidence of leukemia in the early years following chemotherapy, although the duration of effect and the specific agents involved are not well understood. Also, some, but not all, studies have indicated that the incidence of certain solid tumors increases following treatment for Hodgkin's disease. PURPOSE: We studied the association between treatment for Hodgkin's disease and the incidence of second cancers. METHODS: We conducted a study within a cohort that included 10,472 patients from 14 cancer centers in the United States and Canada who were first diagnosed as having Hodgkin's disease at some point from 1940 through 1987. Discounting the 1st year after diagnosis, the average length of follow-up was 7.1 years per subject. RESULTS: We observed 122 leukemias and 438 solid tumors. The relative risk (RR) of leukemia following chemotherapy, compared with no chemotherapy, was 14 (95% confidence interval [CI] = 5.6-35). Increased risks of leukemia were observed after treatment with chlorambucil (RR = 2.0; 95% CI = 1.1-3.6), procarbazine (RR = 4.9; 95% CI = 2.6-9.1), vinblastine (RR = 1.7; 95% CI = 1.1-2.8), and a group of rarely used drugs that included methotrexate, vindesine, etoposide, and 22 others (RR = 3.8; 95% CI = 1.9-7.4). RRs were also estimated for various combinations of drugs, including MOPP (mechlorethamine, vincristine, procarbazine, and prednisone) (RR = 5.9; 95% CI = 2.9-12) and ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) (RR = 1.5; 95% CI = 0.7-3.4). The RR of leukemia associated with splenectomy was 1.6 (95% CI = 1.0-2.5). The RR of solid tumors following chemotherapy was 1.4 (95% CI = 1.1-1.8). For the group of rarely used drugs, the RR of solid tumors was 3.1 (95% CI = 1.7-5.8). Chemotherapy was associated with an increased risk of cancers of the bones, joints, articular cartilage, and soft tissues (RR = 6.0; 95% CI = 1.7-20), and cancers of the female genital system (RR = 1.8; 95% CI = 1.1-3.2). In patients followed for 10 or more years after radiotherapy, increased risks were found for cancers of the respiratory system and intrathoracic organs (RR = 2.7; 95% CI = 1.1-6.8) and for cancers of the female genital system (RR = 2.4; 95% CI = 1.1-5.4). CONCLUSIONS: Procarbazine, chlorambucil, and vinblastine are associated with increased leukemia risk. Combination drug regimens have leukemogenic effects estimated as the product of RRs for individual drugs. Chemotherapy and radiotherapy increase the risk of selected solid tumors, and the effect of chemotherapy on solid tumor risk is weaker than the leukemogenic effect. IMPLICATIONS: Without doubt, the benefits of treatment of Hodgkin's disease outweigh the risk of a subsequent malignancy, but data on the carcinogenic effects of radiation and drugs beyond 10 years after treatment continue to be sparse, and future analyses should be directed at long-term survivors.

Adolescent↗
PubMed1995

Characterisation of HEVER, a novel stress-induced gene from Hevea brasiliensis.

A novel stress-induced gene, HEVER (Hevea ethylene-responsive) from the rubber tree, Hevea brasiliensis, has been isolated and characterised. HEVER is encoded by a multigene family. The HEVER transcript is expressed at basal levels in Hevea tissues and is developmentally regulated. In addition, the HEVER transcript and protein are induced by stress treatment with salicylic acid and ethephon. Sequence analysis shows that HEVER encodes a 33 kDa protein that has significant homology to the hypothetical protein SLEXORFA-1 from the plant, Stellaria longipes, and two bacterial proteins, BAC180K-75 from Bacillus subtilis and MVRNO3-1 from Methanococcus vannielii.

Amino Acid Sequence↗