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Biomedical subjects

M K Chan

Publications and source records attributed to M K Chan.

At least 181 records · Page 10Linked to original sources
PubMed1976

The class-specific immunoglobulin composition of fluids obtained from various levels of the canine respiratory tract.

Sensitive and specific radioimmunoassays capable of accurately measuring the three major classes of canine immunoglobulins in the 50 to 200 ng/ml range were developed. The concentrations of IgG, IgA, and IgM in samples of fluid obtained from various levels of the canine respiratory tract (stimulated saliva, tracheal washes, and bronchopulmonary lavage supernatants) and in serum were determined by using the radioimmunoassays. The composition of the immunoglobulin classes, expressed as per cent of the total immunoglobulin content of each sample, differed markedly among the respiratory tract-derived fluids and between respiratory fluids and serum. Pilocarpine-stimulated saliva contained predominantly IgA while bronchial washes contained predominantly IgG. The contents of IgA and IgG in tracheal washes were intermediate between those of stimulated saliva and bronchial washes. There appeared to be a progressive decrease in the content of IgA (83% to 19%) and a progressive increase in the content of the IgG (6.3% to 75%) as sampling proceeded from the upper to the lower respiratory tract. The mean IgG/IgA ratios were as follows: stimulated saliva, 0.1; tracheal washes, 2.1; bronchial washes, 4.1; and serum, 23.2. All respiratory tract-derived fluids contained small amounts of IgM. Local and systemic immunization with sheep erythrocytes failed to alter the per cent composition of immunoglobulins in bronchial washes during the primary immune response. The results demonstrate major differences in the composition of immunoglobulins derived from the upper as opposed to the lower respiratory tract. The findings suggest that functional differences may exist in the immunologic apparatus associated with various levels of the respiratory tract.

Animals↗
PubMedDate not supplied

Percutaneous ethanol injection as a possible curative treatment for malignant portal vein thrombosis in hepatocellular carcinoma.

Postoperative residual hepatocellular carcinoma (HCC) with malignant portal vein thrombosis in a 48-year-old man was cured with transarterial chemoembolization (TACE) for the parenchymal portion and percutaneous ethanol injection (PEI) for the malignant portal vein thrombosis. No evidence of tumor recurrence was noted after 18 months of follow-up. The only severe complication in our patient was biliary stricture which was treated with an internal stent via endoscopic retrograde pancreatico-cholangiography (ERCP).

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Middle aortic syndrome in a boy with arteriohepatic dysplasia (Alagille syndrome).

Middle aortic syndrome is increasingly recognized as a cause of hypertension in adolescents and young adults. Alagille syndrome is a genetic disorder characterized by hepatic, eye, and bony abnormalities. Cardiovascular lesions occur in most of the patients, but narrowing of the abdominal aorta has not been previously recorded. We present an unusual association between middle aortic syndrome and Alagille syndrome, with a similar vascular lesion seen in two generations.

Adolescent↗
PubMedDate not supplied

Continuous ambulatory peritoneal dialysis (CAPD) in diabetic patients with end-stage renal failure in Hong Kong.

The authors' experience in managing 17 diabetic patients among their first 100 consecutive patients treated with continuous ambulatory peritoneal dialysis (CAPD) was reviewed. The diabetics were significantly older than the non-diabetics, but their biochemistry was comparable to that of the non-diabetics. With three exchanges a day, the requirement for antihypertensives was high (60%). Exit-site infection occurred at a rate of one episode per 9.7 patient-months, and the frequency of peritonitis averaged one episode per 9.4 patient-months; the main culprit was Staphylococcus pyogenes. Rehabilitation was good because the patients had to finance their treatment. In spite of old age, 23% worked full-time. There was no progressive increase in serum cholesterol or triglycerides. Glycemic control was good and was comparable whether the patients were given insulin subcutaneously or intraperitoneally. There was a highly significant (p less than 0.001) positive correlation between fasting blood glucose levels and HbA1 concentrations. Fasting blood glucose concentrations did not correlate with either serum cholesterol or triglyceride concentrations. Diabetic retinopathy progressed in five patients, to the point that their vision was severely impaired. There was no relationship between the degree of glycemic control and progression of diabetic retinopathy. Two patients died of cardiovascular causes, but there were no peritonitis-related deaths. Cummulative patient survival at 2 years was 86%, and the corresponding technique survival, 100%.

Adult↗
PubMedDate not supplied

Genetic lesion in the carcinogenesis of cervical cancer.

Allelic loss at specific chromosomal loci was demonstrated in carcinoma of the cervix (CaCx) obtained from Hong Kong Chinese by restriction fragment length polymorphism analysis. Altogether 12 patients with CaCx, 7 with cervical intraepithelial neoplasia (CIN) and 7 with normal cervical tissues were studied. Polymorphic DNA markers for chromosome 3 were used and the tumour and constitutional genotypes of the above patients were compared. Loss of heterozygosity (LOH) was found in 10 out of 12 informative cases with CaCx at RAF-1 locus (3p25) and in 10 out of 11 cases at D3S3 (3p14). Further study on patients with cervical intraepithelial neoplasia showed LOH at both 3p25 and 3p14 in four out of five cases. In normal cervical tissues, no LOH was demonstrated at both loci. Our data suggest that the deletion events occurring on the short arm of chromosome 3 at 3p25 and 3p14 are early events in the development of carcinoma of cervix. Since recessive genes have been reported to reside within or close to these 2 loci, important genes may have been lost or inactivated in the genesis of this tumour. Moreover, human papillomavirus (HPV) type 16, 18 or 33 was found in 8/12 of the carcinomas and 4/7 of CIN using Polymerase Chain Reaction and/or Southern Blot hybridization, confirming the close association with human papillomavirus. Whether the observed genetic lesions in the short arm of chromosome 3 in cervical "premalignant" and malignant lesions and their consistent association with high risk HPV represent independent events in the development of carcinoma of cervix will be discussed.

Alleles↗
PubMedDate not supplied

Cytodiagnosis of 112 salivary gland lesions. Correlation with histologic and frozen section diagnosis.

Aspirates of 112 cases of salivary gland lesions with histologic correlation were reviewed. Fifty-five cases (49%) had frozen sections made. The 112 cases included 76 cases of benign lesions (31 cases of pleomorphic adenoma, 19 of Warthin's tumor and 26 of nonneoplastic lesions), 22 of primary salivary gland malignancy and 14 of metastatic malignant lesions. The overall accuracy in diagnosing benign and malignant lesions was 95%. The accuracy in diagnosing the exact category of neoplastic lesions was 70%. The diagnostic sensitivity for malignant lesions was 86% and the specificity, 99%. There was one false positive, in which a pleomorphic adenoma was diagnosed as small cell carcinoma. Five false-negative cases were encountered that were due to underdiagnosis of mucoepidermoid carcinoma and adenoid cystic carcinoma. The smears were reviewed, and the diagnostic pitfalls are discussed. A comparison of the cytodiagnosis and frozen section diagnosis was made. In frozen sections there were two false negatives, and two diagnoses were deferred. The overall diagnostic accuracy was 91%. The accuracy in diagnosing the exact category of neoplastic disease was 77%. The diagnostic sensitivity for malignant disease was 70% and specificity, 100%. Frozen section, however, did supplement the fine needle aspiration diagnosis in 13 cases.

Adolescent↗
PubMedDate not supplied

Integration of HPV-16 DNA in cervical carcinoma cell line CC3/CUHK3 and its xenografts.

A recently established cell line, designated CC3/CUHK3, derived from a squamous cell carcinoma of the uterine cervix of a Hong Kong Chinese patient was investigated for its association with human papillomavirus (HPV) by Southern blot hybridization studies. A "grafted tumour" or xenograft of CC3/CUHK3 has also been successfully established in athymic mice, which showed similar histology to that of the original biopsy. The epithelial nature of the xenografts, like the original biopsy. The epithelial nature of the xenografts, like the original tumour specimen, was also confirmed by transmission electron microscopy which demonstrated the presence of desmosomes and tonofilaments. Moreover transmission electron microscopic examination revealed no HPV particle in either the tumour biopsy or the xenograft tissues. Analysis of the DNA samples extracted from the cervical cancer cell line and the xenograft tissues derived from it showed the presence of HPV type 16 DNA. No DNA sequence related to HPV type 6, 11, or 18 was demonstrated. The viral DNA was found to be integrated into the cellular genome at multiple sites as single copy or head-to-tail tandem repeats. Deletion or rearrangement of the HPV DNA had probably occurred on or subsequent to integration. Viral sequence deletion has also been observed in the grafted tumours derived from CC3/CUHK3.

Animals↗
PubMedDate not supplied

Fine needle aspiration cytodiagnosis of nasopharyngeal carcinoma in cervical lymph nodes. A study of 40 cases.

The cytologic features of fine needle aspiration (FNA) samples of 40 metastatic nasopharyngeal carcinomas in cervical lymph nodes were reviewed. FNA was performed with 21-gauge or 23-gauge needles; the FNA smears were stained with the Papanicolaou stain or with hematoxylin and eosin. Several typical cytologic features were noted. All cases showed the presence of clusters of cohesive tumor cells, most of which were undifferentiated. Medium-sized oval vesicular nuclei were present in 85% of the cases; all cases had prominent nucleoli. The cytoplasm was generally pale, with ill-defined boundaries in 87.5% of the cases. Mitoses were present in 75% of the cases. Mature lymphocytes were intermingled with tumor cells in all cases. The cytologic features correlated with the histologic features in surgical biopsies of the nasopharynx and lymph nodes. The results show that FNA of cervical lymph nodes can aid in the diagnosis of otherwise occult nasopharyngeal carcinoma and in detecting residual or recurrent nodal disease in patients with nasopharyngeal carcinoma who had undergone treatment.

Adult↗
PubMedDate not supplied

Detection of Epstein-Barr virus-associated antigen in fine needle aspiration smears from cervical lymph nodes in the diagnosis of nasopharyngeal carcinoma.

Epstein-Barr virus (EBV) has consistently been shown to be associated with undifferentiated nasopharyngeal carcinoma, and an EBV-associated nuclear antigen (EBNA) has been detected in the cells of nasopharyngeal carcinoma. A study on the applicability of EBNA detection in fine needle aspiration (FNA) smears from cervical lymph nodes in the diagnosis of metastatic nasopharyngeal carcinoma was performed. All 11 cases (100%) with metastatic nasopharyngeal carcinoma showed EBNA-positive tumor cells, characterized by bright, granulated nuclear fluorescence. Three (50%) of six cases with other metastatic head and neck carcinomas also showed EBNA-positive tumor cells. These findings suggest that the presence of EBNA-positive tumor cells in FNA smears from cervical lymph nodes is not specific for metastatic nasopharyngeal carcinoma. On the other hand, a negative result in the presence of tumor cells may help to exclude it. A larger study is required to verify these preliminary findings.

Antigens, Viral, Tumor↗