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Biomedical subjects

R Chetty

Publications and source records attributed to R Chetty.

At least 109 records · Page 6Linked to original sources
PubMed1997

Inflammatory pseudotumour and Rosai-Dorfman disease of soft tissue: a histological continuum?

A lesion of the chest wall in a 34 year old woman, which had a combination of histological and immunophenotypic features of inflammatory pseudotumor and Rosai-Dorfman disease of soft tissue, is described. There was considerable overlap in the pathogenesis, histology and immunophenotype of these two lesions. The similarities between these two lesions suggest that there is a temporal sequence and a histological continuum with early histiocyte-rich and late fibroblast- and myofibroblast-rich lesions. Alternatively, the morphological and immunophenotypic features could be because of aberrant cytokine expression in an inflammatory pseudotumour, resulting in transformation of histiocytes to resemble those seen in Rosai-Dorfman disease.

Adult↗
PubMed1997

Relation between retinoblastoma and p53 proteins in human papilloma viruses 16/18 positive and negative cancers of the uterine cervix.

AIM: To ascertain the extent of retinoblastoma protein (pRB) expression in comparison to p53 protein and human papilloma viruses (HPV) 16/18 status in cervical carcinomas. METHODS: Fifty cases of invasive cervical carcinoma were HPV typed for genotypes 16 and 18 using consensus primers by polymerase chain reaction (PCR). Immunohistochemistry for pRB and p53 was done on formalin fixed tissue using microwave antigen retrieval and commercially available antibodies. RESULTS: Forty five cases were squamous carcinomas, three were adenocarcinomas, and two were adenosquamous carcinomas. Thirty one cases were HPV 16 positive and one was HPV 18. Sixteen cases showed +4 pRB expression and a further 11 were +3 positive. Seven cases were negative. Only five cases (10%) showed +4 p53 immunostaining, while seven were negative and 15 were +1. Of the 16 pRB +4 positive cases, one was negative for p53 and a further seven were +1 positive. This inverse pattern of staining between pRB and p53 had a p value of < 0.001. No correlation was observed between HPV 16/18 status and p53 and/or pRB staining. CONCLUSIONS: pRB is expressed in the majority of cases of cervical cancer (86%), with more than 75% (+4) of the tumour cell population being positive in 16 cases (32%). There appears to be a general inverse pattern of staining between pRB (high) and p53 (low) in cervical cancer. The expression of both pRB and p53 proteins is independent of the HPV 16/18 status of the tumour.

Adenocarcinoma↗
PubMed1997

CD31 (JC70) expression in plasma cells: an immunohistochemical analysis of reactive and neoplastic plasma cells.

AIMS: To investigate the immunohistochemical expression of CD31 (JC70) in normal and neoplastic plasma cells. METHODS: Plasma cells in bone marrow biopsies and extramedullary locations were examined. All extramedullary biopsies were formalin fixed and paraffin embedded. The bone marrow biopsies were fixed in formal acetic acid and embedded in paraffin wax. Twenty multiple myelomas (12 bone marrow and eight extramedullary deposits), 10 extramedullary plasmacytomas, and 30 biopsies with reactive plasma cells (10 bone marrow, 20 extramedullary biopsies) were stained with anti-CD31 (JC70) using the streptavidin-biotin detection system with diaminobenzidine as a chromogen. Antigen retrieval in bone marrow biopsies was achieved by pressure cooking. In all other biopsies, antigen retrieval was achieved by microwave pretreatment. RESULTS: All 20 extramedullary cases with reactive plasma cells showed intense membrane staining. Focal staining was detected in reactive plasma cells in bone marrow biopsies. Five of 10 plasmacytomas showed membrane staining. None of the cases of multiple myeloma, either medullary or extramedullary, showed any immunoreactivity for CD31. CONCLUSIONS: CD31, a member of the immunoglobulin supergene family of cell adhesion molecules, is strongly expressed in extramedullary reactive plasma cells, focally in bone marrow reactive plasma cells, and occasionally in extramedullary plasmacytomas.

Cohort Studies↗
PubMed1997

Cyclin D1 and retinoblastoma protein expression in oesophageal squamous cell carcinoma.

AIMS: To assess the immunoexpression of cyclin D1 and retinoblastoma in a cohort of oesophageal squamous cell carcinoma cases from South Africa to see whether there is a relation between these two proteins. In addition, protein expression was correlated with clinicopathological features. METHODS: Fifty biopsies and 30 oesophagectomy specimens were immunostained with commercially available antibodies to cyclin D1 and retinoblastoma proteins, following microwave antigen retrieval. RESULTS: Twenty three of the 80 cases (29%) showed cyclin D1 protein expression. However, only five cases had > 50% of the tumour cells displaying immunopositivity. Three of the four cases with lymph node spread were cyclin D1 positive in the primary tumour and the metastasis. Fifty three cases were immunoreactive with the antiretinoblastoma antibody; 29 of these cases showing > 50% of cells with immunolabelling. Of the 23 cyclin D1 positive cases, 18 were also retinoblastoma positive. No correlation was observed between cyclin D1 and retinoblastoma protein expression and age, sex, race, or histological grade. CONCLUSIONS: Cyclin D1 is expressed in a minority of cases of oesophageal squamous carcinomas from South Africa. However, three of four cases with lymph node spread were cyclin D1 positive, thus indicating that cyclin D1 positive tumours may have a greater propensity for spread. In addition, 18 of 23 cyclin D1 positive cases also expressed retinoblastoma protein. These findings suggest a possible relation between cyclin D1 and retinoblastoma proteins in a proportion of cases of oesophageal squamous.

Adult↗
PubMed1996

Polycystin, the polycystic kidney disease 1 protein, is expressed by epithelial cells in fetal, adult, and polycystic kidney.

Polycystic kidney disease 1 (PKD1) is the major locus of the common genetic disorder autosomal dominant polycystic kidney disease. We have studied PKD1 mRNA, with an RNase protection assay, and found widespread expression in adult tissue, with high levels in brain and moderate signal in kidney. Expression of the PKD1 protein, polycystin, was assessed in kidney using monoclonal antibodies to a recombinant protein containing the C terminus of the molecule. In fetal and adult kidney, staining is restricted to epithelial cells. Expression in the developing nephron is most prominent in mature tubules, with lesser staining in Bowman's capsule and the proximal ureteric bud. In the nephrogenic zone, detectable signal was observed in comma- and S-shaped bodies as well as the distal branches of the ureteric bud. By contrast, uninduced mesenchyme and glomerular tufts showed no staining. In later fetal (>20 weeks) and adult kidney, strong staining persists in cortical tubules with moderate staining detected in the loops of Henle and collecting ducts. These results suggest that polycystin's major role is in the maintenance of renal epithelial differentiation and organization from early fetal life. Interestingly, polycystin expression, monitored at the mRNA level and by immunohistochemistry, appears higher in cystic epithelia, indicating that the disease does not result from complete loss of the protein.

Adult↗
PubMed1996

An immunohistochemical study of TAL-1 protein expression in leukaemias and lymphomas with a novel monoclonal antibody, 2TL 242.

Fifty formalin fixed, paraffin-embedded cases of T-acute lymphoblastic leukaemia (T-ALL) from 12 bone marrow trephines and 38 lymph nodes were stained with a new monoclonal antibody, 2TL 242, raised against recombinant TAL1 protein. The antibody recognizes TAL-1 polypeptides of molecular weight 39 and 41 kD (full length). In addition, a variety of other leukaemias and lymphomas were also stained with 2TL 242. Twenty-four of the 50 cases of T-ALL showed nuclear positivity, ranging from 10 to 90 per cent of leukaemic cells. A positive staining reaction was nuclear and stippled in pattern. Nuclear staining was not seen in any other type of leukaemia or lymphoma. Five cases of follicular lymphoma showed diffuse cytoplasmic staining of variable intensity. Although some background staining is obtained with this antibody, positive nuclear staining is easily distinguishable. This monoclonal antibody has a potential role in primary diagnosis and in the detection of minimal residual disease in T-ALL.

Antibodies, Monoclonal↗
PubMed1996

bcl-2 protein is strongly expressed in post-transplant lymphoproliferative disorders.

The aim of this study was to examine a series of Epstein-Barr virus (EBV)-driven post-transplant lymphoproliferative disorder (PTLDs), in order to ascertain the level of bcl-2 immunostaining; to explore the relationship between bcl-2 and p53 protein expression and to see if any correlation exists between bcl-2 and EBV-latent membrane protein 1 (LMP-1). Seventeen renal and 11 heart/heart-lung PTLD cases were stained with antibodies to EBV-LMP-1, bcl-2 and p53, using paraffin-embedded tissue. All cases of PTLD strong co-expressed bcl-2 and EBV-LMP. Positive staining was present in small lymphoid and larger immunoblastic cells. These two antibodies showed parallel staining intensity. p53 expression was noted in 13 of 17 renal PTLDs, but in ten of the positive cases only 5-10 per cent of cells were stained. Seven of the 11 heart/heart-lung cases showed 50-60 per cent of cells to be p53-positive; in the remaining for cases, 10-20 per cent of cells were positive. bcl-2 protein, as detected by immunohistochemistry, is markedly overexpressed in all case of PTLD. This study also demonstrates a strongly positive correlation between bcl-2 expression and EBV-LMP-1 detection in PTLD. An inverse pattern of p53 and bcl-2 immunoexpression is noted in PTLDs with "high grade' histology: these show marked expression of bcl-2, while p53 is downregulated. A Fisher's exact test yielded a P value of 0-12 when comparing p53-positive renal PTLDs with p53-positive heart/heart-lung PTLDs, indicating that any difference seen is not statistically significant. The postulated mechanism for the positive correlation between bcl-2 and EBV-LMP-1 is that EBV upregulates bcl-2, either directly or indirectly, thus promoting cell survival and ultimately successful viral replication.

Adult↗
PubMed1996

EBV latent membrane protein (LMP-1) and bcl-2 protein expression in Reed-Sternberg-like cells in post-transplant lymphoproliferative disorders.

An inconsistent association exists between EBV-LMP-1 and bcl-2 protein expression in Reed-Sternberg cells seen in Hodgkin's disease. In fact, many studies have concluded that there is no correlation between EBV-LMP and bcl-2 expression in Hodgkin's disease. We undertook an analysis of post-transplant lymphoproliferative disorders to explore the relationship between EBV-LMP and bcl-2 in Reed-Sternberg-like cells found in this condition, given the strong association between this disorder and EBV. Reed-Sternberg-like cells were found histologically in 11 of 28 cases of renal, heart and heart-lung post-transplant lymphoproliferative disorders. Formalin-fixed, paraffinembedded sections were stained with monoclonal antibodies to EBV-LMP-1 and bcl-2 proteins. Reed-Sternberg-like cells in all 11 cases co-expressed EBV-LMP and bcl-2. A similar relationship was noted with large, mononuclear cells and occasional small lymphoid cells. The staining pattern seen with both antibodies was of similar intensity and both displayed cytoplasmic Golgi accentuation. In the setting of post-transplant lymphoproliferative disorders. Reed-Sternberg-like cells exhibit strong co-expression of EBV-LMP-1 and bcl-2 proteins, supporting a positive correlation between them. This is in contrast to the findings in Hodgkin's disease. The reason for this discrepancy may be due to the iatrogenic immunosuppression and resultant severe EBV infection, together with other cellular events.

Herpesvirus 4, Human↗
PubMed1996

The immunoexpression of bcl-2 and p53 in Kaposi's sarcoma.

The aim of this study was to examine the immunohistochemical expression of p53 and bcl-2 in Kaposi's sarcoma and relate this with proliferation index (as measured by MIB-1 staining) and clinicopathological subtypes. Twenty formalin-fixed, paraffin-embedded cases of Kaposi's sarcoma were stained with commercially available antibodies to p53, bcl-2 and MIB-1, after pressure cooking antigen retrieval. All cases were strongly positive for bcl-2 with the majority containing more than 75% positive cells. In comparison, p53 expression was less striking. Eleven cases contained less than 24% (+1) of cells staining positively. Only two cases showed greater than 75% of positive cells, and both of these latter two lesions had metastasized. The MIB-1 staining in all cases of Kaposi's sarcoma was strongly positive, irrespective of clinicopathological type, in keeping with the highly proliferative nature of this lesion. Thus, we have demonstrated uniformly increased expression of bcl-2 protein in Kaposi's sarcoma irrespective of clinicopathological subtype and MIB-1 staining, while p53 expression is relatively less common, except in those cases which have metastasized. This may help identify those cases that will behave in a more aggressive manner. However, more cases need to be evaluated to verify this.

Adolescent↗
PubMed1996

Thymidine phosphorylase expression in Kaposi sarcoma.

AIMS: To examine the immunohistochemical distribution of thymidine phosphorylase (TP) in all clinicopathological subtypes of Kaposi sarcoma. METHODS: Thirty two biopsy specimens of Kaposi sarcoma (29 patients) were studied. Six of these patients represented classic, six endemic, eight HIV associated, seven post-immunosuppression/transplant related, and two unclassified variants of Kaposi sarcoma. The average age was 49 years (range 22-83 years) and the male: female ratio 24:5. Four samples of angiosarcoma and one of spindle cell haemangio-endothelioma were stained in parallel. All specimens were fixed in formalin, embedded in paraffin wax and processed routinely. Immunohistochemistry was carried out using an antibody directed against CD31 (JC70) and the monoclonal antibody P-GF.44C against TP. RESULTS: All biopsy specimens showed immunoexpression for TP. The spindle cell component stained more strongly than newly formed endothelium lined vessels and normal, resident vessels at a distance from the lesions. CONCLUSIONS: The strong immunoexpression of TP suggests up-regulation of TP and a role for TP in angiogensis in Kaposi sarcoma. The mechanism for the up-regulation of TP remains unknown, but viral infections may trigger it. The differential staining of the various cell components of Kaposi sarcoma also suggest that TP either plays a role in the differentiation and maturation of Kaposi sarcoma or is a reflection of such changes.

Adult↗
PubMed1995

A single center randomized trial assessing use of a vascular hemostasis device vs. conventional manual compression following PTCA: what are the potential resource savings?

We undertook a randomized controlled trial comparing VasoSeal, a collagen vascular hemostasis device (VHD), with manual compression to assess its role and potential cost savings in the PTCA population. Of 460 patients, 359 were excluded due to clinical instability (30%), groin problems (18%), suboptimal PTCA result (15%), and other reasons (37%). The remaining 101 patients were randomized to either VHD (51) or manual compression (50). Hemostasis time, time to ambulation, duration of hospital stay, and nursing time and intensity were significantly reduced in the VHD group. There were no major groin complications in either treatment arm but there was a trend toward more minor groin complications in the VHD patients. The application of VasoSeal reduced resource use in this randomized study and may translate into significant cost reductions in the general coronary angioplasty population.

Adult↗