PubMed Health⌕ Search

Biomedical subjects

M Teh

Publications and source records attributed to M Teh.

At least 37 records · Page 2Linked to original sources
PubMed1994

HLA-DR antigen expression in colonic adenomas and adenocarcinomas.

Previous studies have shown that malignant transformation is sometimes associated with the aberrant expression of HLA class II antigens. The functional significance of such aberrant expression is not known. Since HLA-DR antigen is expressed in normal colonic mucosa, it would be interesting to see if malignant transformation could result in the aberrant suppression of this antigen. Sixteen colonic adenocarcinomas, 29 colonic adenomatous polyps and 23 samples of normal colonic mucosa, including 9 cases of colonic mucosa adjacent to carcinoma, were stained immunohistochemically for HLA-DR antigen. The intensity and distribution of the antigen staining in the cytoplasm and luminal surface of the epithelial elements were analysed semiquantitatively. The lymphoplasmacytic infiltrate in the lamina propria was also evaluated. Cytoplasmic HLA-DR antigen expression was found to be significantly diminished in moderately and poorly differentiated adenocarcinomas but not in adenomas or well-differentiated adenocarcinomas. This suggests that the change in HLA-DR expression is not intrinsic to the neoplastic process but may merely be due to the fact that malignant cells, as they become less differentiated, tend to show alterations in their antigenic phenotype.

Adenocarcinoma↗
PubMed1994

Clinical importance of p53 protein in gall bladder carcinoma and its precursor lesions.

AIMS: To study the expression and importance (if any) of p53 protein in gall bladder carcinoma and its precursor lesions. METHODS: Immunohistochemical staining was performed on formalin fixed, paraffin wax embedded histological sections with an anti-human p53 monoclonal antibody (DO-7; Dako Corporation M7001) (24 carcinomas, one adenocarcinoma in situ, six dysplasias, three adenomas and four cases of chronic cholecystitis). Invasive, in situ, and dysplastic areas as well as normal-looking epithelium were sought. Nuclear staining was assessed according to intensity and extent of positive cells. Both variables were graded on a scale of 1-3 and aggregate p53 scores were obtained (range: 0, 2-6). Only p53 scores of > or = 3 were regarded as significant. RESULTS: Clinically important amounts of p53 were expressed in 92% of invasive carcinomas, 86% of carcinoma in situ, and 28% of dysplastic areas. None of the adenomas contained clinically important amounts of p53. Normal epithelium, present in all the cases, did not express p53 except in one case of moderately differentiated adenocarcinoma (p53 score 3). In general, there was no difference in the prevalence of p53 protein expression between dysplasias associated with, and those unassociated with invasive disease. There was a tendency for higher grade carcinomas to express more p53 protein. CONCLUSIONS: The distribution of p53 protein in invasive carcinomas and the adjacent dysplastic and preinvasive lesions suggests that it is more commonly expressed than previously thought. The fact that p53 protein is also expressed in cases of dysplasia and carcinoma in situ unassociated with invasive malignancy lends further support to the contention that p53 gene mutations may have a role in the pathogenesis of gall bladder cancer. Expression of p53 protein may possibly be an indication of likely disease progression from dysplasia, to carcinoma in situ, to invasive disease.

Adenocarcinoma↗
PubMed1994

The expression of HLA-DR antigen in cervical neoplasia.

The purpose of this study was to evaluate the relationship between cervical neoplasia and HLA-DR antigen (class II antigen) expression. Seventy-seven formaldehyde-fixed uterine specimens comprising morphologically normal cervix (12), chronic cervicitis (10), cervical intraepithelial neoplasia (CIN) of various grades (42), and invasive squamous cell carcinoma (13) were studied for the degree and type of inflammation, and immunohistochemically for the HLA-DR antigen expression in the epithelium. The nonneoplastic ectocervical squamous epithelium was consistently negative for HLA-DR antigen, even in sections showing significant lymphoplasmacytic infiltration. We found HLA-DR antigen positivity in endocervical glandular epithelium, immature metaplastic squamous epithelium, CIN, and invasive carcinoma. In cases of CIN, the aberrant expression of the antigen generally corresponded to the level of dysplasia. Specific cells exhibiting koilocytic change were negative. All the cases of squamous cell carcinoma expressed the antigen, albeit variable in intensity and distribution. These findings suggest that aberrant HLA-DR antigen expression in the uterine ectocervix may be a consequence of dysplastic changes of the squamous epithelium that is maintained even after malignant transformation. On the other hand, HLA-DR positivity in immature metaplastic epithelium is probably a mere reflection of the fact that normal endocervical glandular epithelium can express the antigen.

Carcinoma, Squamous Cell↗
PubMed1993

An immunohistochemical study of ras oncoprotein expression in gastric carcinoma.

BACKGROUND: Previous studies have shown that ras oncoprotein is overexpressed in gastric carcinoma. It is unsettled whether there is differential expression of this oncoprotein in the two major subtypes of gastric carcinoma--intestinal type and diffuse type. METHODS: Forty-four cases of gastric carcinomas (24 intestinal type, 18 diffuse type, and 2 mixed according to the Lauren classification) were analyzed for ras oncoprotein expression using commercially available antibodies in routinely formaldehyde-fixed, paraffin-embedded tissue sections. RESULTS: Altogether, 13 cases stained unequivocally, and these appeared as granular cytoplasmic staining in tumor cells. Only five were intestinal-type carcinomas; the remaining eight were diffuse type and included two intramucosal carcinomas. When the comparison between the two subtypes was limited only to the poorly differentiated carcinomas, the difference was statistically significant (P < 0.05). ras Oncoprotein also was strongly expressed in normal duodenal mucosa as well as areas of gastric intestinal metaplasia. CONCLUSIONS: These results suggest that the strong expression of ras oncoprotein in gastric intestinal metaplasia may be merely a reflection of metaplastic change to an intestinal epithelial phenotype. The differential expression of ras oncoprotein between diffuse-type and poorly differentiated intestinal-type gastric carcinoma implies that these are two distinct subtypes of gastric carcinoma.

Adenocarcinoma↗
PubMed1993

Papillary carcinoma arising in a thyroglossal cyst.

Carcinoma arising in a congenital thyroglossal cyst is rare, with less than 150 cases reported worldwide. This is a case report of a papillary carcinoma arising within a thyroglossal cyst in a 51 year old woman. Management of this condition remains controversial. Most of these tumours arise from ectopic thyroid tissue within the cyst. Prognosis is good as metastasis is uncommon. Sistrunk procedure is adequate if histology does not reveal extracystic extension.

Carcinoma, Papillary↗
PubMed1993

Histogenesis of true splenic cysts: a histological and immunohistochemical study.

Three true splenic cysts were studied histologically and immunohistochemically using antibodies against Ber-EP4, CEA, factor-VIII related antigen and several cytokeratins of varying molecular weights. Two cysts were lined by cuboidal and columnar cells with extensive squamous metaplasia. The columnar cells have the immunophenotype of mesothelial cells being positive for keratin but negative for Ber-EP4 and CEA. The third cyst occurred in a wandering spleen and was lined by hobnail columnar cells with cilia resembling tubal epithelium of Fallopian tube. The immunophenotype was that of epithelial cells being positive for both keratin and Ber-EP4. It is likely that true splenic cysts originate from invagination of the capsular mesothelial lining. The frequent occurrence of stratified squamous epithelium is attributed to squamous metaplasia secondary to haemorrhage and irritation. On the other hand, the presence of tubal epithelium in true splenic cysts is more likely to be due to the innate potentiality of mesothelial cells to differentiate along Mullerian line and may be a manifestation of the secondary Mullerian system. The cyst lining cells were negative for factor-VIII related antigen and thus offered no support for an origin from endothelium.

Adult↗
PubMed1992

HLA-DR antigen expression in intestinal-type and diffuse-type gastric carcinoma.

The expression of the HLA-DR antigen, a Class II HLA antigen, was analyzed in 41 cases of gastric carcinoma (23 intestinal-type and 18 diffuse-type according to a modified Lauren classification) using a monoclonal antibody that is reactive to this antigen in routinely formalin-fixed, paraffin-embedded tissue sections. Seventeen cases of intestinal-type gastric carcinoma and two cases of diffuse-type gastric carcinoma were positive for the HLA-DR antigen. The staining in intestinal-type carcinoma generally was stronger and more extensive than in diffuse-type carcinoma, which showed only weak and focal staining. The difference in the frequency and pattern of staining between intestinal and diffuse-type gastric carcinoma supports the concept that these are two distinct subtypes of gastric carcinoma.

Adenocarcinoma↗
PubMed1992

Effects of polyphenolic natural products on the lipid profiles of rats fed high fat diets.

Male Wistar rats were fed a high fat diet (HFD) containing 2.5% cholesterol and 16% lard supplemented with polyphenolic natural products namely quercetin, morin or tannic acid (100 mg/rat/day) for 4, 7 and 10 wk. Rats fed HFD without the supplements served as control. The effects of these compounds on blood lipid profiles, enzymes, liver fat and aorta of the rat were studied. In rats fed HFD containing tannic acid, plasma total cholesterol (TC), low density lipoprotein cholesterol (LDLC) and triglyceride (TG) were reduced by 33.3%, 29.6% and 65.1%, respectively, at week 10. High density lipoprotein cholesterol (HDLC) concentration was not altered. Fat deposition was also decreased in the liver of these rats. Morin significantly reduced plasma TG (65.1%) and liver fat only at week 7 while at week 10 it reduced plasma TC and LDLC by 30.9% and 29.3% respectively. The plasma HDLC concentration was increased by 47.3% at week 4 but no effect was seen at weeks 7 and 10. In the rats fed HFD containing quercetin, plasma HDLC was increased by 28.6% at week 7 but at week 10, plasma LDLC was increased by 21.2%. Quercetin did not cause any significant changes on the plasma TC, TG and liver fat at weeks 4, 7 and 10. Plasma alanine aminotransferase, alkaline phosphatase and bilirubin in control and treated groups were not significantly different. However, hepatic lipase activity in rats fed tannic acid was significantly lower. Aortae of all groups of rats showed no abnormalities. The present report indicates that tannic acid and morin are effective in reducing plasma and liver lipids when supplemented with a high fat diet in rats.

Animals↗
PubMed1992

Helicobacter pylori and gastric cancer: correlation with gastritis, intestinal metaplasia, and tumour histology.

This study aimed to examine the association between Helicobacter pylori, histological gastritis, and intestinal metaplasia in gastric cancers of different histological types. A total of 169 gastrectomy specimens received in one pathology department were studied. Altogether 156 were adenocarcinomas (intestinal type 87, diffuse type 50, mixed type 19). Gastritis occurred in 137 of 163 body specimens (84%) and in 126 of 131 antral specimens (96%). Its presence was unrelated to tumour histology. Atrophic gastritis was more common in both body and antral mucosa in intestinal type compared with diffuse type carcinoma. This was also true for intestinal metaplasia of the body, but not of the antral mucosa. H pylori was present in 101 of 163 (62%) body specimens and 56 of 131 (43%) antral specimens. In intestinal type carcinoma, H pylori was found in 52/84 (62%) body specimens and in 24/70 (34%) antral specimens, while the corresponding figures for diffuse type carcinoma were 29/48 (60%) and 17/38 (45%) respectively. Tumour histology therefore had no influence on the occurrence of H pylori. Tumour site had no effect on the presence or absence of gastritis, atrophic changes, intestinal metaplasia, or H pylori. While both H pylori and gastritis are associated with gastric cancer, the association is unrelated to tumour histology and may not be a causal one.

Adenocarcinoma↗
PubMed1992

Association of Helicobacter pylori with HLA-DR antigen expression in gastritis.

AIMS: To assess the association between Helicobacter pylori-associated gastritis and HLA-DR antigen (class II antigen) expression. METHODS: Fifty endoscopic gastric biopsy specimens were studied for the presence of H pylori, degree and type of inflammation, and for HLA-DR antigen expression in the epithelium. The cases were chosen to represent different categories: inflamed gastric mucosa with (n = 13) and without (n = 20) H pylori, and non-inflamed mucosa (n = 17). RESULTS: The antigen was aberrantly expressed in the antral mucosal epithelium in 11 of 12 cases (92%) with acute-on-chronic gastritis when H pylori was also present. It was present in the antrum in only seven of 18 H pylori negative cases (39%) with acute-on-chronic/chronic gastritis. One of three cases of acute gastritis and three of seven cases of chronic gastric erosions (non-inflamed category) showed positive staining. Generally, there was more staining in the antral than body mucosa and in the surface/foveolar epithelium than in the glands. No aberrant HLA-DR antigen expression was found in the 10 cases of normal gastric mucosa examined. CONCLUSIONS: These findings suggest that H pylori may have a role in the induction of class II HLA antigen expression in chronic gastritis and lend support to the view that these organisms may be responsible for part of the inflammatory response.

Acute Disease↗
PubMed1992

Expression of HLA-DR antigen in different histological types of gastric polyp.

AIMS: To study the expression of HLA-DR antigen in the different histological types of gastric polyps. METHODS: Ninety five cases of gastric polyps were histologically classified and examined for the presence of Helicobacter pylori, and for degree and type of inflammation. Further sections were stained immunohistochemically for HLA-DR antigen expression in the epithelium using a monoclonal antibody that was reactive to formalin-fixed paraffin wax embedded tissue. RESULTS: HLA-DR antigen was expressed in all of the inflammatory polyps studied (20/20), and in most hyperplastic (12/16) and adenomatous (4/6) polyps. Only a few fundic gland polyps (8/51) stained positively for HLA-DR antigen. Gastric polyps seem to have a greater tendency to express HLA-DR antigens than non-polypoid gastric mucosa, even after considering the factors that may affect HLA-DR antigen expression, such as inflammation and the presence of H pylori. CONCLUSIONS: Growth disturbances/polyp formation may be associated with increased HLA-DR antigen expression.

Adolescent↗
PubMed1991

Malignant glandular triton tumor.

A case of left brachial plexus-related malignant peripheral nerve sheath tumor showing neoplastic, glandular, and rhabdomyoblastic elements in a 39-year-old Chinese man is reported. The authors suggested that this tumor be termed a malignant glandular triton tumor in view of the presence of the adenocarcinomatous component. The patient had extensive local recurrence comprising mainly the Schwann spindle cells within a year after complete piecemeal removal and died 15 months later after the initial presentation. The natural behavior of this tumor, as in other reported cases of malignant triton tumor, is extremely aggressive, unlike malignant schwannoma or glandular malignant schwannoma. The histogenesis of this tumor is likely to be from primitive neural crest cells, Schwann's cell precursors, or metaplastic malignant Schwann's cells.

Adult↗
PubMed1991

Lectin histochemistry of ovarian mucinous cystadenomas.

The lectin histochemistry of ovarian mucinous cystadenoma was studied using a panel of lectins comprising Triticum vulgaris, Lotus tetragonolobus, Arachis hypogaea, Griffonia simplicifolia I, concanavalin A, and Dolichus biflorus. All 23 cases examined in this study stained extensively with T. vulgaris. Of all the lectins, D. biflorus was the least reactive. Concanavalin A stained mainly the perinuclear zone, whereas the other lectins frequently stained the cytoplasm, glycocalyx, and extracellular luminal mucin. This pattern of lectin reactivity resembles endocervical more than intestinal epithelium and suggests that ovarian mucinous cystadenomas are of müllerian nature. The lack of difference in lectin reactivity between cystadenomas with and without goblet/Paneth cells supports a common histogenetic origin of both groups.

Concanavalin A↗
PubMed1991

Paraneoplastic optic neuropathy in nasopharyngeal carcinoma--report of a case.

A 31-year-old Chinese man developed left optic neuritis with left sectorial field loss as a remote effect of nasopharyngeal carcinoma. The field defect showed interesting fluctuations in response to the dosage of systemic steroid therapy. Neuropathologic findings from an exploratory craniotomy did not show any gross tumour mass around the left optic nerve nor any histological evidence of tumour infiltration. This case illustrates that "optic neuritis" could be a paraneoplastic effect of nasopharyngeal carcinoma.

Adult↗
PubMed1989

Spindle and epithelioid cell nevus of tongue at an unusual site.

A case of spindle and epithelioid cell nevus of the tongue is presented. It shows unusual and distinctive desmoplasia and cells containing melanosomes identified by histochemical and electron microscopic techniques. We believe this is the second case, but the first fully documented report, of this unusual nevus of tongue reported in the literature.

Adult↗
PubMed1987

Intestinal and diffuse carcinoma of the stomach among the ethnic and dialect groups in Singapore.

This study attempts to determine the relative prevalence of intestinal-type and diffuse-type carcinomas (using a modified Lauren classification of gastric carcinomas) and to evaluate its significance in relation to the difference in stomach cancer risks among the different ethnic and Chinese dialect groups in Singapore. Of the 648 cases of primary adenocarcinoma of the stomach studied, 405 (62.5%) were of the intestinal type, 206 (31.8%) of the diffuse type, and 37 (5.7%) of the mixed type. Men had higher proportions of intestinal-type carcinoma than women. The intestinal-diffuse carcinoma ratio increased progressively with age. Although the relative intestinal-diffuse carcinoma ratios in women appeared to reflect the relative incidence rates of stomach cancer of the different ethnic and dialect groups, the ratios in men were inconsistent. Indian men had a higher intestinal-diffuse carcinoma ratio than Chinese men despite a lower incidence of stomach cancer. Hokkien men had the highest incidence of stomach cancer and the lowest intestinal-diffuse carcinoma ratio among the Chinese dialect groups. The use of the ratio as an indicator of relative risks for gastric cancer between populations of different genetic makeup is inconsistent and unreliable.

Adenocarcinoma↗
PubMed1985

Thrombotic complication of umbilical arterial catheterization and its sequelae.

Umbilical arterial catheterization caused major complications including 5 deaths in 25 of 230 infants who underwent autopsy at the Kandang Kerbau Hospital in a two-and-a-half year period beginning May 1982. Arterial thrombosis developed in 25 of 129 (19.3%) autopsies with a history of umbilical arterial catheterization. Pathological sequelae of thrombosis occurred in 14 cases (peripheral gangrene 1, renal 6, gastrointestinal 3 and both renal and gastro-intestinal 4). The sequelae were clinically unsuspected in the majority. Early deaths were uncommon in the group with thrombosis. Comparison of neonatal factors revealed no significant differences between the group with sequelae and those without. Infants with indwelling umbilical arterial catheter should be actively monitored for complications.

Aorta, Abdominal↗