Expression of mutant p21ras induces insulin-like growth factor 1 secretion in thyroid epithelial cells.

There is substantial evidence supporting the existence of insulin-like growth factor 1 (IGF-1) autocrine circuits in many tumor types, although the underlying inducing event has remained undefined. In order to address this matter, we have generated several immortalized human thyroid epithelial cell lines containing a zinc-inducible mutant H-ras gene and used these to investigate the relationship between expression of mutant p21ras and secretion of IGF-1. Induction of the transgene in the presence of zinc ions (Zn2+) was confirmed by Northern blot analysis and immunocytochemistry. IGF-1 levels in serum-free medium, stripped of binding proteins, were monitored using a sensitive radioimmunoassay. Expression of mutant p21ras in these cells, induced by Zn2+, resulted in an approximate 30-fold increase in the IGF-1 production rate, reaching a level exceeding that of human embryo fibroblasts. The data presented here suggest that an activating mutation of a ras oncogene may directly account for IGF-1 secretion in some human tumor cells.

Ecto-5'-nucleotidase: localization in rat kidney by light microscopic histochemical and immunohistochemical methods.

We demonstrated the distribution pattern of ecto-5'-nucleotidase (5'-Nu) in rat kidney by enzymatic activity (lead salt precipitation) and by immunohistochemistry with a polyclonal antibody raised in rabbits. Enzyme activity was found in the brush border of the proximal tubule, highest in the P1 segments with decreasing intensity in the P2 segments and weakest in P3 segments in the medullary rays of the cortex. The P3 segments of the outer stripe showed slightly higher activity. Activity was also apparent in the intercalated cells in the connecting tubule and collecting duct, whereas all other tubular and glomerular structures were negative. Activity in peritubular and perivascular connective tissue was highest in the cortical labyrinth, weak or absent in the medullary rays of the cortex, and entirely absent in the medulla. The distribution of the antigen was fully congruent with that of the enzyme activity. With respect to the role of adenosine in regulation of renal blood flow and glomerular filtration rate, the distribution of 5'-Nu in the cortical interstitium may be particularly significant. The possibility of nucleotide cleavage at the brush-border membranes may be important for salvage of nucleotides from the tubular lumen.

Food security in a perfect storm: using the ecosystem services framework to increase understanding.

Achieving food security in a 'perfect storm' scenario is a grand challenge for society. Climate change and an expanding global population act in concert to make global food security even more complex and demanding. As achieving food security and the millennium development goal (MDG) to eradicate hunger influences the attainment of other MDGs, it is imperative that we offer solutions which are complementary and do not oppose one another. Sustainable intensification of agriculture has been proposed as a way to address hunger while also minimizing further environmental impact. However, the desire to raise productivity and yields has historically led to a degraded environment, reduced biodiversity and a reduction in ecosystem services (ES), with the greatest impacts affecting the poor. This paper proposes that the ES framework coupled with a policy response framework, for example Driver-Pressure-State-Impact-Response (DPSIR), can allow food security to be delivered alongside healthy ecosystems, which provide many other valuable services to humankind. Too often, agro-ecosystems have been considered as separate from other natural ecosystems and insufficient attention has been paid to the way in which services can flow to and from the agro-ecosystem to surrounding ecosystems. Highlighting recent research in a large multi-disciplinary project (ASSETS), we illustrate the ES approach to food security using a case study from the Zomba district of Malawi.

Variability of antiepileptic medication taking behaviour in sudden unexplained death in epilepsy: hair analysis at autopsy.

BACKGROUND: Variable compliance with antiepileptic drugs (AEDs) is a potentially preventable cause of sudden unexplained death in epilepsy (SUDEP). Hair AED concentrations provide a retrospective insight into AED intake variability. METHODS: We compared hair AED concentration variability in patients with SUDEP (n = 16), non-SUDEP epilepsy related deaths (n = 9), epilepsy outpatients (n = 31), and epilepsy inpatients (n = 38). AED concentrations were measured in 1 cm hair segments using high performance liquid chromatography. Individual patient hair AED concentration profiles were corrected for "washout" using linear regression analysis. The coefficient of variation (CV) of the corrected mean hair AED concentration provided an index of variability of an individual's AED taking behaviour. Hair sample numbers varied between subjects, and so weighted regression estimates of the CV were derived for each group. RESULTS: The CV regression estimates for each group were: SUDEP 20.5% (standard error 1.9), non-SUDEP 15.0% (3.9), outpatients 9.6% (1.4), and inpatients 6.2% (2.7). The SUDEP group therefore showed greater hair AED concentration variability than either the outpatient or the inpatient groups (p<0.0001). CONCLUSION: Observed variability of hair AED concentrations, reflecting variable AED ingestion over time, is greater in patients dying from SUDEP than in either epilepsy outpatients or inpatients. SUDEP, at least in a proportion of cases, appears preventable.

Pancytopaenia from a disseminated anaplastic oligodendroglioma.

The rarity of extraneural metastases from a central nervous system (CNS) tumour may mean that the manifestations of a metastatic lesion are confused with a second pathology. This report concerns a patient who developed a fatal and clinically unexplained, pancytopaenia 3 months after removal of an anaplastic oligodendroglioma. Postmortem revealed widespread bone marrow dissemination of the CNS primary and a solitary liver metastasis. A brief review of the literature and some possible reasons for the rarity of extracranial metastases are discussed.

In vitro responsiveness to serum growth factors is inversely related to in vivo malignancy in human thyroid epithelial cells.

We have examined the proliferative response (DNA synthesis) of primary thyroid epithelial cultures to serum and a defined serum-substitute. These cultures were derived from normal human thyroid and from thyroid adenomas and carcinomas. All normal cultures showed a dose-dependent response, with a maximum 3H-thymidine labelling index of around 50%. Three out of the four adenomas demonstrated a much reduced or delayed response under the same conditions. In two carcinomas, labelling was never more than 5% and in one case was undetectable. This inverse relationship between the degree of in vivo malignancy and proliferative response in vitro has important implications for the interpretation of tissue culture models of epithelial neoplasia and also offers the potential for isolating novel growth factors specific for thyroid cancer cells.

Silicone plastinated pathology specimens and their teaching potential.

Plastination is a process of tissue preservation by impregnation with silicone polymers or epoxy resins. The resulting specimens are dry, odourless, durable, life-like, non-hazardous, maintenance-free, and do not deteriorate with time. The technique may be easily mastered by those with a basic knowledge of histology laboratory practice. A small-scale system is relatively inexpensive to establish and specimens are comparable in cost to traditional 'pots'. Plastinated specimens are a useful adjunct to the teaching of pathology, anatomy, radiology, and surgery, and are particularly suited to use in small groups. They are much preferred to conventional 'pots' by both students and teachers owing to their accessibility, superior illustrative powers, and comparative ease of interpretation.

Induction of cell death by stimulation of protein kinase C in human epithelial cells expressing a mutant ras oncogene: a potential therapeutic target.

Ras oncogene activation is a key genetic event in several types of human cancer, making its signal pathways an ideal target for novel therapies. We previously showed that expression of mutant ras sensitizes human thyroid epithelial cells to induction of cell death by treatment with phorbol 12-myristate 13-acetate (PMA) and other phorbol esters. We have now investigated further the nature and mechanism of this cell death using both primary and cell line models. The cytotoxic effect of PMA could be blocked by bisindolylmaleimide (GF 109203X), a well-characterized inhibitor of c and n protein kinase C (PKC) isoforms, and by prior down-regulation of PKC, indicating that it is mediated by acute stimulation, rather than down-regulation. Western analysis identified two candidate isoforms--alpha and epsilon--both of which showed PMA-induced subcellular translocation, either or both of which may be necessary for PMA-induced cell death. Immunofluorescence showed that PMA induced a rapid nuclear translocation of p42 MAP kinase of similar magnitude in the presence or absence of mutant ras expression. Cell death exhibited the microscopic features (chromatin condensation, TdT labelling) and DNA fragmentation typical of apoptosis but after a surprising lag (4 days). Taken together with recent models of ras-modulated apoptosis, our data suggest that activation of the MAPK pathway by PMA tips the balance of pro- and anti-apoptotic signals generated by ras in favour of apoptosis. The high frequency of ras mutations in some cancers, such as cancer of the pancreas, which are refractory to conventional chemotherapy, together with the potential for stimulating PKC by cell-permeant pharmacological agents, makes this an attractive therapeutic approach.