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Biomedical subjects

R Chetty

Publications and source records attributed to R Chetty.

At least 181 records · Page 10Linked to original sources
PubMed1991

Muco-epidermoid and adenoid cystic carcinomas of the tracheobronchial tree.

Muco-epidermoid and adenoid cystic carcinomas of the respiratory tree are uncommon and warrant attention because of controversy and uncertainty surrounding their behaviour and management. Ten cases of these tumours are detailed, with emphasis on approach to management. Careful attention should be paid to histological grading of muco-epidermoid carcinomas. Low grade tumours, completely excised, behave the best. Adenoid cystic carcinomas are slow-growing, relentlessly progressive tumours and difficult to eradicate locally. Surgery remains the best therapeutic tool available.

Adult↗
PubMed1991

An unusual thyroid cyst. A case report.

A solitary hydatid cyst in a 69-year-old woman presented as a cold area on thyroid scan. Clinically, it forms part of the differential diagnosis of neoplastic thyroid lesions. Surgery is effective for this uncommon thyroid cyst.

Aged↗
PubMed1990

Primary thyroid lymphomas. A clinicopathological study of 8 cases.

Eight elderly women with primary non-Hodgkin's lymphoma were treated with a combination of surgery, chemotherapy and radiation with excellent outcome. Clinically, the patients presented with thyromegaly and did not have lymphadenopathy or hepatosplenomegaly. On histological examination, the lymphomas resembled diffuse follicle-centre cell tumours. All patients showed extension beyond the thyroid capsule and lympho-epithelial lesions; 3 displayed kappa-light-chain restriction and 2 lambda-monoclonality. Thyroid lymphomas fall into the spectrum of mucosa-associated lymphomas, which have a better prognosis than their equivalent nodal-based counterparts.

Aged↗
PubMed1990

Giant cell hepatocellular carcinoma.

A terminal case of giant cell hepatocellular carcinoma, subsequent to Hepatitis B-associated macronodular cirrhosis is presented, illustrated and discussed. The uncommon finding of malignant ascites, in itself atypical of hepatocellular carcinoma, with an almost exclusive content of giant cells as the cellular component, was a feature of this unusual variant of hepatocellular carcinoma.

Adult↗
PubMed1990

Extraskeletal mesenchymal chondrosarcoma of the mediastinum.

Extraskeletal mesenchymal chondrosarcoma is a rare tumour with a predilection for the meninges and lower limb, especially the thigh region. This paper reports an extraskeletal mesenchymal chondrosarcoma occurring in the posterior mediastinum, a previously undocumented site.

Adult↗
PubMed1990

Hürthle cell medullary carcinomas of the thyroid gland.

Two medullary carcinomas of the thyroid (MCTs) composed entirely of Hürthle (oncocytic or oxyphilic) cells and containing follicular structures are described. Immunocytochemical analysis showed these tumours to be calcitonin-, carcino-embryonic antigen- and neuron-specific enolase-positive. The essence of this communication is twofold. Firstly, it highlights and draws attention to this unusual variant of MCT, which may be encountered at frozen section and misdiagnosed as a Hürthle cell tumour of follicular cell origin. Secondly, it undertakes a concise overview of the immunocytochemistry of Hürthle cell thyroid neoplasms and MCT.

Aged↗
PubMed1990

Malignant transformation in fibrous dysplasia. A report of 3 cases.

Three patients with fibrous dysplasia were encountered in whom osteosarcoma subsequently developed. A review of published reports and the authors' experience establishes fibrous dysplasia as a premalignant bone lesion. Radiation appears to enhance the inherent tendency towards malignant transformation.

Adult↗
PubMedDate not supplied

Primary aorto-esophageal fistula due to Takayasu's aortitis.

BACKGROUND: Aneurysmal dilatation in Takayasu's arteritis is a recognized complication; however, fistula formation, especially to the esophagus, is very rare. METHODS: A 22-year-old male presented with severe hematemesis. Investigation by means of esophagogastroscopy and CT scan revealed a saccular aneurysm in the proximal descending aorta with communication to the esophagus. The patient was taken to theater, the aneurysm excised and replaced by a graft. RESULTS: Gross examination of the aneurysm showed multiple points of outpouching from the aneurysm. Histopathological examination of the showed marked intimal fibromyxoid thickening, loss of outer medial muscle and elastic fibers and marked fibrosis of the adventitial layer. The histological features were in keeping with Takayasu's arteritis. No evidence of tuberculosis was noted. CONCLUSIONS: This case illustrates an unusual complication of Takayasu's arteritis, in the form of a fistula between the aorta and the esophagus, which resulted in massive hematemesis and the ultimate demise of the patient.

Adult↗
PubMedDate not supplied

The role of steroid contraceptive hormones in the pathogenesis of invasive cervical cancer: a review.

Invasive cervical cancer remains a leading cause of morbidity and mortality, especially among women in the developing world where screening is either deficient or absent. Of all agents linked to the causation of this disease, high-risk human papillomavirus (HPV) appears to be the strongest factor. However, not all women with HPV develop cervical cancer. Steroid contraception has been postulated to be one mechanism whereby HPV exerts its tumorigenic effect on cervical tissue. Steroids are thought to bind to specific DNA sequences within transcriptional regulatory regions on the HPV DNA to either increase or suppress transcription of various genes. Although some earlier studies were reassuring as no increased incidence of cervical cancer was observed, subsequent research has shown a causative association, especially among long-term users. The role of steroids was further enhanced by the discovery of hormone receptors in cervical tissue. Some earlier studies of oral contraceptive steroids found no increased risk, even after controlling for other risk factors, including smoking and number of partners. However, prospective studies have shown a greater progression of dysplasia to carcinoma-in-situ with more than 6 years of oral steroid contraceptive use. Similar findings were also evident from other work, including the Royal College of General Practitioners Oral Contraception Study. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives showed a relative risk of 1.2 for invasive cancer in users of the long-acting progestational contraceptive, depo-medroxyprogesterone acetate. However, in users of more than 5 years duration, an estimate of 2.4 was reported. The upstream regulatory region (URR) of the HPV type 16 viral genome, mediates transcriptional control of the HPV genome and is thought to contain enhancer elements that are activated by steroid hormones. It has been shown that steroid hormones bind to specific glucorticoid-response elements within HPV-DNA. Experimental evidence has revealed that high-risk type HPV 16 are able to stimulate the development of vaginal and cervical squamous cell carcinomas in transgenic mice exposed to slow-release pellets of 17 beta-estradiol in the presence of human keratin-14 promoter. Squamous cell carcinomas developed in a multi-stage pathway only in transgenic mice and not in nontransgenic mice. The E6 oncoprotein of HPV 16 has been shown to bind to the p53 tumor suppressor gene and stimulate its degradation by a ubiquitin-dependent protease system. Steroid hormones are thought to increase the expression of the E6 and E7 HPV 16 oncogenes, which in turn bind to and degrade the p53 gene product, leading to apoptotic failure and carcinogenesis. However, the molecular basis of this remains to be proven.

Contraceptives, Oral, Hormonal↗
PubMedDate not supplied

P53 codon 72 polymorphism and BRCA 1 and 2 mutations in ovarian epithelial malignancies in black South Africans.

Mutations in the BRCA and p53 tumor suppressor genes are implicated in the oncogenesis of ovarian tumors although their exact roles remain unclear. Despite recognized ethnic differences in the frequency of ovarian cancer and in genetic polymorphisms between populations, studies carried out so far have focused almost entirely on Caucasian subjects. In this study, undertaken at King Edward VIII Hospital, Durban, South Africa, we examined blood and/or primary epithelial ovarian tumor tissue from 75 black South African women for the presence of the three most commonly occurring BRCA 1 and 2 mutations (185delAG, 5382insC and 6174delT). The p53 codon 72 allele status was also examined and results were compared to a reference cohort comprising 340 ethnically matched subjects. None of the BRCA 1 or 2 mutations were detected in the patient group. The codon 72 Arg allele frequency in lymphocytic DNA was not significantly different compared with the control group. In contrast, in ovarian tumor DNA, the Arg allele was found significantly more frequently than in the controls; this was observed in terms of both Arg allele frequency (45% vs. 31%; P = 0.017) and Arg homozygosity (20% vs. 9%; P = 0.039). Tumors with the more aggressive serous papillary cystadenomatous histology had a markedly higher Arg frequency (45%) than the mucinous cystadenomas (25%). The higher frequency of the Arg allele detected in this study in black South Africans with ovarian tumors suggests a possible role in malignant transformation and may constitute a risk factor for ovarian and other epithelial cancers through mechanisms yet to be elucidated.

Adult↗
PubMedDate not supplied

Differences in adiponectin protein expression: effect of fat depots and type 2 diabetic status.

Adiponectin is an adipocyte-derived hormone associated with insulin sensitivity and atherosclerotic risk. As central rather than gluteofemoral fat is known to increase the risk of type 2 diabetes and cardiovascular disease, we investigated the mRNA and protein expression of adiponectin in human adipose tissue depots. RNA was extracted from 46 human adipose tissue samples from non-diabetic subjects aged 44.33 +/- 12.4 with a BMI of 28.3 +/- 6.0 (mean +/- SD). The samples were as follows: 21 abdominal subcutaneous, 13 omentum, 6 thigh; samples were also taken from diabetic subjects aged 66.6 +/- 7.5 with BMI 28.9 +/- 3.17; samples were: 6 abdominal subcutaneous; 3 thigh. Quantitative PCR and Western analysis was used to determine adiponectin content. Protein content studies determined that when compared with non-diabetic abdominal subcutaneous adipose tissue (Abd Sc AT) (values expressed as percentage relative to Abd Sc AT -100 %). Adiponectin protein content was significantly lower in non-diabetic omental AT (25 +/- 1.6 %; p < 0.0001, n = 6) and in Abd Sc AT from diabetic subjects (36 +/- 1.5 %; p < 0.0001, n = 4). In contrast, gluteal fat maintained high adiponectin protein content from non-diabetic patients compared with diabetic patients. An increase in BMI was associated with lower adiponectin protein content in obese ND Abd Sc AT (25 +/- 0.4 %; p < 0.0001). These findings were in agreement with the mRNA expression data. In summary, this study indicates that adiponectin protein content in non-diabetic subjects remains high in abdominal subcutaneous fat, including gluteal fat, explaining the high serum adiponectin levels in these subjects. Omental fat, however, expresses little adiponectin. Furthermore, abdominal and gluteal subcutaneous fat appears to express significantly less adiponectin once diabetic status is reached. In conclusion, the adipose tissue depot-specific expression of adiponectin may influence the pattern of serum adiponectin concentrations and subsequent disease risk.

Adipocytes↗
PubMedDate not supplied

The interaction between steroid hormones, human papillomavirus type 16, E6 oncogene expression, and cervical cancer.

Various risk factors have been implicated in the causation of cervical cancer including human papillomavirus (HPV), the early genes (E6 and E7 ) of which encode the main transforming proteins. Studies have suggested that steroid hormones may enhance the expression of these genes leading to loss of p53 gene-mediated cell apoptosis. A total of 120 cervical tissue samples were obtained from patients with proven cervical cancer. Patients who used depo-medroxyprogesterone acetate steroid contraception were recruited as part of the steroid arm. Only HPV DNA type 16 samples were used for the study. Controls included three cell lines (CaSki, SiHa, & C33A) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal housekeeping gene. Of 120 patients, there were 111 patients with HPV type 16 identified. Of this number, RNA was present in 63 samples. There were 30 women (30/63) who used steroid contraception. In relation to patients who used contraception, HPV 16 E6 gene expression was present in 79% (n = 23) and 88% (n = 30) of steroid users compared to nonusers, respectively. In total there were 25 patients (40%) with expression of the HPV 16 E6*I gene and 30 patients with expression of the E6*II gene. There were 57% of steroid users (n = 17) who had expression of the E6*I/E6*II gene, compared to 52% (n = 17) of nonusers (P = 0.800). From a molecular level, this study does not confirm the role of injectable progesterones in cervical carcinogenesis.

Adolescent↗
PubMedDate not supplied

Kaposi's sarcoma of the tonsil.

Two cases of Kaposi's sarcoma presenting as tonsilar masses in HIV-positive patients are described. At the time of examination neither patient had other manifestations of AIDS. Both patients also had concomitant cervical lymphadenopathy at the time of presentation, but the tonsillar masses were the dominant clinical findings. Biopsy of both tonsils revealed typical features of Kaposi's sarcoma. Both patients subsequently defaulted treatment and have been lost to follow-up.

Adult↗