Biomedical subjects

P G Murray

Publications and source records attributed to P G Murray.

10 recordsLinked to original sources

PubMed1992

Immunohistochemical demonstration of the Epstein-Barr virus-encoded latent membrane protein in paraffin sections of Hodgkin's disease.

Paraffin sections from 46 cases of Hodgkin's disease were examined for the presence of the Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP) using a sensitive (double layer alkaline phosphatase-anti-alkaline phosphatase) immunohistochemical method. LMP was detected in 22 cases, the majority of positive cases being of nodular sclerosis (12/24), mixed cellularity (6/7), and lymphocyte depletion (3/3) subtypes. Only one of 12 cases of lymphocyte predominant disease was positive. In all cases, reactivity was confined to Hodgkin's and Reed-Sternberg cells. These results provide further evidence for an association between EBV and Hodgkin's disease and indicate that LMP may be readily detected in archival material.

Herpesvirus 4, Human↗

PubMed1992

Epstein-Barr virus (EBV) and Hodgkin's disease in children: incidence of EBV latent membrane protein in malignant cells.

Previous studies have detected EBV DNA by Southern blotting or in situ hybridization in biopsy material from up to 30 per cent of adult cases of Hodgkin's disease. Here we have used monoclonal antibodies specific for the EBV latent membrane protein LMP1 to examine archival material from children with Hodgkin's disease. Material from 74 cases (54 males and 20 females) was examined and 37 (30 males and 7 females) were classified as LMP1-positive in the malignant cells. LMP1 positivity was present in 4/13 (31 per cent) of lymphocyte predominant, 14/36 (39 per cent) of nodular sclerosis, 17/20 (85 per cent) of mixed cellularity, 1/2 (50 per cent) of lymphocyte depletion, and 1/3 (33 per cent) of unclassified subtypes. The positive cases by clinical stage were I 9/22 (41 per cent), II 9/20 (45 per cent), III 11/24 (46 per cent), and IV 8/8 (100 per cent). LMP1 positivity was present in 2/5 (40 per cent) children aged less than 5 years, 12/27 (44 per cent) aged 5-10 years, and 23/42 (48 per cent) aged between 10 and 15 years. The association between EBV and Hodgkin's disease in children thus appeared to be more frequent in patients with mixed cellularity and advanced disease, but examples of EBV-positive tumours were found in all histological subtypes, stages, and ages. Stepwise discriminant function analysis showed that clinical stage IV and mixed cellularity histology are independently associated with LMP1 positivity. These observations indicate that Hodgkin's disease in children is at least as strongly linked to EBV as is the disease in adults.

Adolescent↗

PubMed1991

CD23 expression in non-Hodgkin lymphoma: immunohistochemical demonstration using the antibody BU38 on paraffin sections.

The leucocyte antigen CD23 is upregulated in the early stages of B-cell activation by Interleukin-4 (IL-4), and functions as an IgE receptor and lymphocyte growth factor. We have studied the expression of CD23 in 68 cases of non-Hodgkin lymphoma (NHL) using the antibody BU38. This new antibody has the great advantage of being applicable to routinely-processed paraffin sections. CD23 was expressed in tumour cells in 27 out of 36 cases of low grade NHL and 3 out of 32 cases of high grade NHL. Follicular dendritic cells were strongly positive and were seen in follicular lymphomas. Macrophages were also positive and were numerous in high grade lesions.

Antigens, CD↗

PubMed1991

Phorbol ester and phospholipase C-mediated differentiated thyroid function in vitro: the effects of protein kinase C inhibition and downregulation.

Tumor-promoting phorbol esters, e.g., 12-O-tetradecanoylphorbol 13-acetate (TPA), inhibit TSH-stimulated iodide organification in vitro implying a role for protein kinase C (PKC) in the regulation of differentiated thyroid function. To further explore the PKC dependence of this action of TPA, we studied the effects of PKC inhibition and downregulation on phorbol-mediated differentiated thyroid function in vitro. In addition, the effects of the nonphorbol PKC activator, phospholipase C (PLC) were studied. TPA (100 nM) inhibited TSH-stimulated iodide organification in cultured porcine thyroid cells by over 95% and caused PKC translocation in vitro. Exogenous PLC (1 U/mL) could mimic these effects of TPA. The PKC inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) inhibited TSH-stimulated iodide organification at concentrations exceeding 10 microM. However, partial recovery of phorbol- and PLC-inhibited iodide organification was seen in the presence of identical concentrations of H7. H7 had no effect on PKC translocation in porcine thyroid cell extracts. After 24 h of TPA treatment to induce PKC downregulation, no recovery of TSH-stimulated iodide organification was observed, suggesting that the effects of TPA were irreversible. These studies indicate that the effects of TPA and PLC on differentiated thyroid function are mediated, at least in part, by PKC. These findings provide further evidence for a role for PKC in the regulation of differentiated thyroid function.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1990

Sequential demonstration of nucleolar organizer regions and Ki67 immunolabelling in non-Hodgkin's lymphomas.

In order to investigate the relationship between the numbers of interphase silver-stained nucleolar organizer regions (AgNORs) and cell proliferation, we have studied prospectively a small series of non-Hodgkin's lymphomas (NHL). We applied the recently described double staining technique for sequential immunostaining and the AgNOR reaction to the same sections of tumour from each case. The immunostaining was performed with the antibody Ki67, known to demonstrate the nuclei of proliferating cells. A significant difference was found between the AgNOR scores in Ki67+ and Ki67- cells, the counts being much higher in the former than the latter. This was the case for both high- and low-grade NHL and is further evidence that interphase AgNOR counts reflect cell proliferation level, at least in lymphomas.

Antibodies, Monoclonal↗

PubMed1989

Sequential demonstration of antigens and AgNORs in frozen and paraffin sections.

A technique has been designed which enables the sequential demonstration of nucleolar organizer regions (NORs) and various antigens, in both frozen and paraffin wax-embedded sections. The NORs were demonstrated by the standard argyrophil (AgNOR) method and the antigens were shown by either immunoperoxidase (PAP) or immunoalkaline phosphatase (alkaline phosphatase-anti-alkaline phosphatase or avidin-biotin-alkaline phosphatase) methodology. Clear, reproducible results were obtained and AgNOR sites were enumerated with ease. It is suggested that the sequential method may be of great use in the evaluation of AgNOR numbers in neoplasms, where cell populations are heterogeneous. Cell populations may be demarcated with accuracy prior to the counting the AgNORs.

Antigens↗

PubMed1988

Translocation of protein kinase C in porcine thyroid cells following exposure to thyrotropin.

We have previously shown that protein kinase C activators modulate differentiated thyroid function in vitro; however, how protein kinase C may be activated physiologically is unknown. The present studies were undertaken in order to determine whether TSH could activate protein kinase C in vitro. Following exposure of porcine thyroid cells to TSH, translocation of protein kinase C from the cytosol to its membrane-bound form was observed. Maximal translocation occurred at the lowest TSH concentration able to trigger this response (10 mU/ml) but persisted at higher concentrations (20-100 mU/ml). Time-course studies revealed that translocation of protein kinase C was seen only after 40 min. TSH could also produce a similar translocation in human neutrophils (known to have TSH receptors). In thyroid cells pre-treated with TSH, modulation of phorbol-mediated protein kinase C translocation was noted. These results indicate that TSH causes the translocation of protein kinase C in porcine thyroid cells (and possibly other TSH receptor-containing cells) and therefore may regulate the action of protein kinase C on differentiated thyroid function.

Animals↗

PubMed1988

Effects of protein kinase C activators on the in-vitro action of thyrotrophin in pigs.

The ability of the non-phorbol protein kinase C (PKC) activator 12-hydroxy-daphnetoxin (mezerein) to modulate differentiated thyroid function was examined in vitro. A dose-dependent inhibition of TSH-stimulated iodide organification was observed in porcine thyroid cells exposed to mezerein. Under identical conditions mezerein caused the translocation of PKC from its inactive cytosolic form to an active membrane-bound form in thyroid cell extracts. The relative biological potencies of mezerein and the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), to inhibit thyroid function in vitro corresponded to their abilities to activate PKC. This effect was also observed when dibutyryl cyclic AMP was used, implying a post-receptor site of action. To provide further evidence for this concept, the effects of mezerein and TPA on receptor-related events were studied. Neither mezerein nor TPA had any effect on the binding of radiolabelled TSH to solubilized porcine thyroid membranes. However, both mezerein and TPA were capable of stimulating cyclic AMP (cAMP) production in porcine thyroid cells in the basal state but could not augment TSH or forskolin-activated cAMP release. These data provide evidence that activation of PKC plays a role in the regulation of differentiated thyroid function in vitro and suggest that the effects of PKC are complex, with independent actions on cAMP accumulation and post-receptor events.

Animals↗

PubMed1987

The effects of dithiothreitol on thyroid stimulation in vitro.

There is evidence that the porcine TSH receptor contains essential disulphide bridge(s) which can be disrupted by dithiothreitol (DTT). The aim of the present study was to determine whether exposure of intact thyroid cells to DTT leads to altered thyroid stimulation. TSH-stimulated iodine organification in cultured porcine thyroid cells was studied following short-term DTT exposure; a dose-dependent inhibition was observed with DTT but not oxidized DTT. Cell viability, follicle formation, and total protein synthesis were preserved. A minimum of 30 min incubation with DTT was required for inhibition. However, under identical conditions, DTT had no effect on TSH or forskolin-stimulated cyclic AMP (cAMP) production. These results suggest that DTT inhibition of organification is mediated by post-receptor mechanisms likely involving thyroid peroxidase. The effects of DTT on thyroid stimulation in vitro does not appear to involve disruption of the disulphide bridge(s) in the TSH receptor.

Animals↗

PubMed1986

Protein kinase C activators modulate differentiated thyroid function in vitro.

Exposure of porcine thyroid cells to the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) leads to inhibition of differentiated thyroid function. We investigated whether this effect is mediated via protein kinase C activation. TPA, phorbol 12,13-didecanoate and phorbol 12,13-dibutyrate inhibited TSH-stimulated iodine organification in porcine thyroid cells by 98, 96 and 45%, respectively. Non-tumour promoting phorbol esters had no effect. The diacylglycerol analogue, sn-1,2-dioctanoylglycerol had similar but quantitatively less activity than TPA. Dibutyryl cAMP could not reverse any inhibition noted. Under conditions that caused significant inhibition of differentiated function, TPA caused translocation of thyroidal protein kinase C from the cytosol to its membrane-bound form. These data provide evidence that the mechanism of phorbol action on thyroid function in vitro includes activation of protein kinase C.

Animals↗