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C T Chew

Publications and source records attributed to C T Chew.

16 recordsLinked to original sources
PubMed1998

Epstein Barr virus (EBV) antibodies in the diagnosis of NPC--comparison between IFA and two commercial ELISA kits.

BACKGROUND: Antibodies to Epstein Barr Virus (EBV) antigens have been used for the diagnosis of nasopharyngeal carcinoma (NPC). While immunofluorescence assays (IFA) of IgA antiviral capsid and early antigens have been the mainstay of this diagnosis, enzyme immunoassays (ELISA) of various EBV antigens are now available. However in almost all of these assays, the sensitivities and specificities have been calculated using blood donors and normal hospital staff as controls, who may not be the most appropriate controls. We wanted to evaluate the usefulness of IFA and ELISA of various EBV antigens in a clinical setting to distinguish between patients with NPC and those suspected of NPC but being biopsy negative. METHODS: Between January 1987 and June 1988, 322 consecutive patients suspected of NPC and who had a post-nasal biopsy were studied. Blood was taken for EBV tests before diagnosis. Tests included IFA and ELISA IgA anti-VCA and anti-EA and ELISA IgA and IgG anti-ribonucleotide reductase, a cloned EA antigen. RESULTS: IFA IgA anti-VCA together with IFA IgA anti-EA both at a cut-off of 1:10 gave the best discrimination between patients with NPC and those suspected of NPC but were biopsy negative. CONCLUSION: The ELISA IgG anti-ribonucleotide reductase test is convenient to perform and looks very promising. An ELISA using a cocktail of cloned EA peptides may be even better.

Antibodies, Viral↗
PubMed1995

T-cell receptor gene expression in tumour-infiltrating lymphocytes and peripheral blood lymphocytes of patients with nasopharyngeal carcinoma.

The T-cell receptor (TCR) repertoire expression of tumour-infiltrating lymphocytes (TILs) from 19 nasopharyngeal carcinoma (NPC) biopsies was compared with those of lymphocytes from 18 control nasopharyngeal biopsies. mRNA was extracted from these lymphocytes and the cDNA transcribed. A panel of 18 V alpha- and 21 V beta-specific primers was used to detect the TCR gene use from cDNA. The use of V alpha and V beta genes was restricted in TILs compared with lymphocytes from biopsies. The frequencies of V alpha 2, V alpha 3, V alpha 9, V alpha 10, V alpha 11, V alpha 13, V alpha 14, V alpha 15, V beta 11, V beta 15 and V beta 20 were decreased and the frequencies of V alpha 10 [Pc = 0.04; relative risk (RR) = 0.05], V alpha 11 (Pc = 0.02; RR = 0.07), V alpha 13 (Pc = 0.002; RR = 0), V alpha 14 (Pc = 0.04; RR = 0.05), V beta 14 (Pc = 0.001; RR = 0.03) and V beta 20 (Pc = 0.001; RR = 0.03) remained significantly reduced after correction for the number of families typed. The frequency of V alpha 17 was higher in NPC biopsies than in NPC PBLs (P = 0.05), and the frequency of V beta 15 was lower in NPC biopsies than in NPC PBLs (P = 0.02). The frequencies of V alpha 17 and V alpha 18 in HLA-B46+ patients were significantly lower (P = 0.009; P = 0.044) than in B46+ controls. The results suggest that the restriction of TCR gene use in NPC patients may be important in NPC pathogenesis.

Base Sequence↗
PubMed1993

Fine needle aspiration of 123 head and neck masses--an initial experience.

Fine needle aspiration (FNA) is a relatively new technique in the investigation of head and neck masses in Singapore. We present our initial experience with 123 neck masses; 82 were lymph nodes, 33 were salivary gland masses and eight were others. The inadequacy rate (percentage of hypocellular yields) was 12.2% with a cytology: histology accuracy rate of 82.6%. The aspiration trolley set-up and improvements in tissue handling reduced the number of inadequate smears. A study of nasopharyngeal carcinoma (NPC) with neck recurrence showed the difficulty encountered with FNA in irradiated necks. In "occult" (clinically normal nasopharynx) NPC with a neck mass as the first presentation, FNA guided us to re-search the nasopharynx.

Biopsy, Needle↗
PubMed1992

Malignant mixed tumour arising from minor salivary gland tissue of the right parapharyngeal space with metastasis to the scalp.

A case of malignant mixed tumour arising from minor salivary gland tissue in the right parapharyngeal space with metastasis to the scalp is described. Both the clinical presentation and the histological picture were unusual. The simultaneous discovery of the primary parapharyngeal tumour and its scalp metastasis, the relatively young age of the patient (43 years-old), the origin of the tumour in minor salivary gland tissue, and the presence of a benign stromal component in the metastasis are features not commonly described in the three entities covered by the term "malignant mixed tumour". We believe this case represents a distinct variant, whose behaviour and progression have not been previously well documented.

Adenoma, Pleomorphic↗
PubMed1992

Oculopharyngeal muscular dystrophy: a case report and a review of literature.

Most muscular dystrophies manifest as peripheral muscular weakness commencing at various age, however, oculopharyngeal muscular dystrophy (OPMD) is a rare hereditary disorder presenting in middle age with progressive dysphagia and bilateral blepharoptosis rather than peripheral muscular weakness. In the medical literature, OPMD has been well described in Canadians of French descent. So far, there is no publication of OPMD in the Malaysia-Singapore medical literature. This article documents this condition in a Chinese patient. A review of the literature is presented and the management of OPMD is discussed.

Aged↗
PubMed1991

Pectoralis major myocutaneous flap reconstruction in head and neck surgery--experience with 60 cases.

The aim of this paper is to evaluate the results of the use of the pectoralis major myocutaneous flap for reconstruction in 60 otolaryngology--head and neck patients over a five year period. There were 52 patients with Stage III (30%) and Stage IV (70%) untreated squamous cell carcinomas. Of the eight recurrent tumours, three patients had nasopharyngeal carcinoma with extensive post-radiation neck failures requiring extended neck dissections and flap reconstruction. The oral cavity and oropharynx were the predominant sites for reconstruction accounting for 70% of the operations performed. Twenty-eight patients had composite resections, ten with pectoralis osteo-myocutaneous flap incorporating a vascularised split sternum bone graft and titanium plate fixation for immediate mandibular reconstruction. All 52 patients underwent post-operative radiation. Major necrosis did not occur but minor tip necrosis of the skin island occurred in two cases (3%). The mean hospitalisation was 19 days for all patients and 21 days for patients with composite resections. The pectoralis major myocutaneous flap in our experience is not only a versatile flap but also a very reliable and robust flap for single stage immediate head and neck reconstruction.

Adult↗
PubMed1991

Retropharyngeal abscess--the foreign body connection.

Retropharyngeal abscesses have been described to be more common among children especially under the age of three or four years and oropharyngeal infection have been implicated as a common etiological factor. However, this series reveals that retropharyngeal abscesses are more commonly seen in adults in our local population. Regional trauma resulting from an ingested foreign body is the leading cause of retropharyngeal abscess in this series. Twenty-three patients seen consecutively between January 1983 and June 1989 at the Department of Otolaryngology, Singapore General Hospital were reviewed retrospectively. Factors such as age, sex, racial distribution, presenting symptoms and signs, methods used to arrive at diagnosis, therapy and complications were studied and analysed. A lateral radiograph of the neck was the single most valuable investigation in the evaluation of the retropharyngeal space. Retropharyngeal and retrotracheal width were measured in 210 normal lateral neck radiographs to establish a normal range in our population. Retropharyngeal widening greater than 5 mm and retrotracheal widening greater than 15 mm was considered significant and was noted in all 23 patients. Regional trauma resulting from an ingested foreign body was the cause of the retropharyngeal abscess in thirteen (56.5%) patients.

Abscess↗
PubMed1991

A cytogenetic study of 74 nasopharyngeal carcinoma biopsies.

Cells from 102 nasopharyngeal biopsies of patients suspected of Nasopharyngeal Carcinoma (NPC) and family members of NPC patients were cultured. Metaphases were successfully obtained from 74 of the biopsies of which 52 were subsequently histologically confirmed to be NPC. Cytogenetical analysis using Q-banding showed abnormalities in 15 cultures, and these included polyploidy, aneuploidy and marker chromosomes. Of the 15 abnormal cultures, 14 were from confirmed NPC patients and in five of these, a consistent 5q+ abnormally was seen involving 5q31. The only other abnormal chromosome changes seen was in a patient with olfactory neuroblastoma.

Asia, Southeastern↗
PubMed1991

Blood loss and transfusion in head and neck tumour surgery.

Major head and neck surgical procedures at the Department of Otolaryngology, Singapore General Hospital during a two year period were reviewed. Sixty-three patients were available for study. Data obtained included tumour site and stage, surgical procedure, duration of operation, preoperative haemoglobin and haematocrit, estimated surgical blood loss, amount of blood ordered and used. Data were grouped by procedure. Temporal bone resections showed the highest average estimate of blood loss (1203 mL) and the highest average blood use (3.0 units), followed by composite resections (1067 mL and 2.3 units) and maxillectomy/midface procedures (616 mL and 1.4 units). The degree of blood loss showed a positive correlation with the duration of operative procedure. The majority of patients (62%) met all criteria to qualify as autologous blood donors making autologous transfusion a feasible option for these patients.

Adolescent↗
PubMed1990

Early diagnosis of nasopharyngeal carcinoma.

Loco-regional metastasis occurs early in nasopharyngeal carcinoma. It may occur before the primary is discernible by routine clinical examination. Advances in immunoserological and molecular-biological methods as well as radiographic imaging techniques including C T Scan and MRI have not dramatically improved the rate of early diagnosis. Elevated IgA antibodies to Epsetin-Barr viral capsid antigen (VCA) and early antigen (EA) serve as a high risk marker. Nasopharyngoscopy and biopsy is still the key to early diagnosis.

Antibodies, Viral↗
PubMed1989

Rett syndrome.

Five girls, aged 2.5 years to 10 years, with Rett Syndrome are presented. The girls (four Chinese and one Indian) demonstrate the classic features of developmental regression with dementia, loss of hand function and stereotyped hand movements. There are as yet no pathognomonic laboratory markers and diagnosis can be difficult especially in the early stages before evolution of the full clinical spectrum. Adherence to current diagnostic criteria is essential. Rett Syndrome is probably not an uncommon cause of severe progressive neurological disability in girls.

Autistic Disorder↗
PubMed1988

Tumour infiltrating lymphocytes in nasopharyngeal carcinoma.

Tumour infiltrating lymphocytes were studied in 28 cases of undifferentiated carcinoma using a panel of monoclonal antibodies. For the T subsets we used OKT4 (helper/inducer), 8 (suppressor/cytotoxic), 11 (pan T), 9 (transferrin receptor) and Dako T6. For the B cells we used polyclonals IgM, D, G and A. Others were HNK-1 (natural-killer cells), THB-5 and W6/32 (HLA-ABC) and HLA-DR. Most of the lymphocytes were T cells and in 26 of 28 biopsies there were more T8 than T4 cells which could be seen around and within the tumour masses. There was also an increase in HNK and T6 cells. Tumour cells were positive for both W6/32 and HLA-DR. Occasional THB-5 positive cell could be seen within tumour masses. All tumour cells stained strongly with keratin and cytokeratin.

Antibodies, Monoclonal↗
PubMed1985

HLA and nasopharyngeal carcinoma in Malays.

HLA associations were observed in unrelated Malay patients with nasopharyngeal carcinoma (NPC). HLA-B18 was observed in 18/45 (40%) Malay NPC patients compared to 22/167 (13%) Malay normals (P = 0.0001; Pc = 0.0027, RR = 4.4). The frequency of HLA-B17, one of the antigens associated with Chinese NPC, was also increased among Malay NPC (13/45 29%) compared to controls (18/167 11%; P = 0.003, Pc = 0.07 RR = 3.4). Similar to the findings among Chinese NPC, the frequency of B17 was higher in early onset (less than or equal to 30 years) Malay NPC resulting in a higher relative risk (RR = 5.0).

Adult↗