A capabilities approach to population health and public policy-making.

BACKGROUND: The objective of this study is to outline a capabilities approach to the social determinants of population health and to compare its explanatory power and implications for public policy-making with psychosocial approaches. METHODS: A model linking the structures of economic and social relations to health outcomes is developed and logistic methods used to confirm its base validity for a representative sample of 16,488 citizens in 19 developed democracies drawn from the World Values Surveys of 1990 and 2005. Self-reported health is the dependent variable. Age, gender, education, employment status, self-mastery, income, autonomy at work, ties to family and friends, subjective social status, associational memberships and sense of national belonging are considered. RESULTS: At baseline, risk ratios reflecting movement from the 25th to 75th percentile in the distribution of the variable indicate that increases in income reduce the likelihood of poor health (0.78; 0.73-0.82) as does higher autonomy at work (0.90; 0.85-0.94) but so does access to social resources reflected in ties to family and friends (0.89; 0.86-0.92), associational memberships (0.93; 0.89-0.98), subjective social status (0.77; 0.54-0.90) while the absence of feelings of national belonging increases the likelihood of poor health (1.14; 1.06-1.23). CONCLUSION: The results suggest that population health is dependent on the distribution of social as well as economic resources along the dimensions predicted by a capabilities model. Governments should be attentive to the impact of policy on the distribution of social, as well as economic, resources.

Tumor suppressors: a developing role for p53?

An increasing body of evidence indicates that p53, the product of a tumour suppressor gene, has a role in development - could this developmental role have provided the primary driving force in the evolution of a protein best known as a stress-response integrator?

The prohibitin family of mitochondrial proteins regulate replicative lifespan.

Cellular senescence is determined by multiple factors, including the genetic regulation of metabolism and responses to endogenous and exogenous stresses [1-4]. Recent studies implicate a limited number of gene products in elongating lifespan in yeast and Caenorhabditis elegans [2-4]; these include the C, elegans gene cik-1, a central regulator of metabolism [5], and yeast RAS2, which controls the response to ultraviolet irradiation and other stresses [3]. Another gene postulated to effect senescence is PHB1, the yeast homologue of prohibitin [3], a rodent gene initially identified as a potential regulator of growth arrest and tumour suppressor [6-8]. Highly conserved prohibitin homologues have been identified in mammals [9], Drosophila [10], C. elegans [9], plants [11] and yeast. A second mammalian gene, encoding BAP37, a protein with sequence similarity to prohibitin, is thought to be involved in lymphocyte function [9]. Here, we show that the nuclear-encoded mammalian prohibitin and BAP37 proteins are present in mitochondria, are co-expressed, and interact physically with each other. Deletion of the Saccharomyces cerevisiae homologues, PHB1 and PHB2, results in a decreased replicative lifespan and a defect in mitochondrial membrane potential. Our observations highlight the relationship between the metabolic efficiency of cells and the ageing process, and provide evidence for its evolutionary conservation.

Cognitive effects of a 30-min aerobic exercise bout on adults with overweight/obesity and type 2 diabetes.

BACKGROUND: Several studies document reliable brain health benefits of acute exercise bouts. However, no prior studies have explored such effects among those living with co-morbid overweight/obesity and type 2 diabetes (T2DM), both of which are conditions associated with cognitive performance decrements. PURPOSE: To examine the impact of a 30-min bout of moderate-intensity aerobic exercise on executive function among adults with overweight/obesity and T2DM, employing a widely used experimental paradigm. METHODS: Thirty adults with overweight/obesity and T2DM were randomly assigned to moderate (30% maximal heart rate reserve) and minimal (r.p.m. 30-50; work load 5) intensity aerobic exercise. Pre-exercise to post-exercise changes in Stroop interference and Go/No-Go scores were compared across conditions. RESULTS: Primary analyses revealed no overall effect of exercise condition on changes in Stroop or Go/No-Go performance. Post-hoc moderation analyses indicated that Stroop interference scores were reduced, following moderate exercise among female participants and among those who were more physically active. CONCLUSION: The current study revealed no reliable benefit of acute aerobic exercise for overweight and obese individuals living with T2DM overall. There may be limited benefits for women and more and active subgroups, but the precise nature of such benefits remains unclear.

Clinical utility of the immunocytochemical detection of p53 protein in cytological specimens.

In the important cytopathological distinction between benign and malignant lesions, there is always a residue of suspicious cases which cannot be satisfactorily diagnosed. Overexpression of the p53 tumor suppressor gene product has been consistently correlated with p53 missense gene mutation and is associated with malignancy. Therefore, assessment of p53 expression may assist in the cytopathological diagnosis of malignancy. Immunohistological assessment of p53 expression has been performed on a prospective series of 1333 nongynecological cytological specimens in the setting of a teaching hospital group. Evaluation of p53 staining was performed without knowledge of cytological diagnosis. Resultant p53 expression data were correlated with cytological diagnosis and clinical information. Of the 999 assessable cases, 956 had a clear cytological diagnosis. In these, p53 overexpression occurred in 108 cases of which 86 were malignant lesions. Of the 848 p53-negative cases, 119 were in fact neoplasms. The false positives were predominantly (19 of 22) reactive mesothelial proliferations, and overexpression occurred in only a small proportion of cells. While the sensitivity of p53 overexpression is low (p53 overexpression only occurring in 41.9% of tumors), the overall specificity is 97%. In the 43 cytopathologically suspicious cases, 7 were p53 positive, all of which proved to be malignant. In this prospective unselected series, we have conclusively demonstrated a close correlation between overexpression of p53 protein and neoplasia. Furthermore, we have shown the possible utility of p53 immunostaining in cytopathology. While there are important technical caveats and some cytological specimens are suboptimal for immunostaining, the data indicate that assessment of p53 is a valuable adjunct to morphological assessment in the analysis of cytopathologically suspicious cases.

The role of p53 in spontaneous and radiation-induced apoptosis in the gastrointestinal tract of normal and p53-deficient mice.

Three h after whole-body irradiation (8 Gy) of C57BL x DBA/2 F1 mice, p53 protein was expressed strongly in the stem cell compartment of the small intestine but at lower levels in the colon. At this time, apoptotic cells were also observed in the stem cell position of the small intestine, with fewer in the colon. In mice without copies of the p53 gene (nulls), the levels of spontaneous apoptosis, in both the small intestine and the colon, were not different from wild-type. Irradiation of the nulls with 8 Gy of gamma-rays failed to induce any further apoptosis: the loss of p53 essentially rendered the epithelial cells, from both the small intestine and the colon, radioresistant. The response of the epithelial stem cells of the small intestine suggests that p53 may play a role in the deletion of damaged cells with carcinogenic potential, whereas this process is limited in the colon.

Characterisation of the interaction between PCNA and Gadd45.

We have examined the interaction between the DNA replication and repair protein PCNA, and the growth arrest and DNA damage induced protein Gadd45. An anti-Gadd45 polyclonal antibody co-immunoprecipitates PCNA but in reciprocal experiments, an anti-C terminal anti-PCNA antibody failed to co-immunoprecipitate Gadd45. We used a yeast two hybrid assay to demonstrate that human Gadd45 interacts with both human and S. pombe PCNA. We have determined that the N-terminal 94 amino acids of Gadd45 bind to PCNA, and using a series of N-terminal and C-terminal deletions of human PCNA we have mapped two potential Gadd45 binding sites. Deletion of the last 6 amino acids of PCNA ablated interaction, suggesting a role in Gadd45 binding. This explains the inability of an anti-C terminal PCNA antibody to co-immunoprecipitate Gadd45. Using a peptide ELISA approach, we showed that Gadd45 protein binds strongly to three regions of PCNA (residues 1-20, 61-80, and 196-215) and weakly to residues 121-170. The crystal structure of PCNA provides insight into our genetic and immunochemical data. Our results confirm an interaction between PCNA and Gadd45, define regions of both molecules involved in this interaction, and are consistent with a potential stoichiometry of 2 Gadd45 molecules to each PCNA monomer. These data provide support for the notion that PCNA-Gadd45 interactions co-ordinate cell cycle and DNA repair.

High levels of p53 protein in UV-irradiated normal human skin.

Exposure of normal adult human skin to doses of UV irradiation that induced mild sunburn resulted in the rapid appearance of p53 protein in the epidermis and superficial dermal fibroblasts. Immunohistological analysis with a panel of antibodies established that while p53 staining was not seen in normal skin it appeared within 2 h of UV exposure. The level of p53 immunostaining peaked at 24 h and returned to undetectable levels within 360 h. The induction of proliferating cell nuclear antigen (PCNA) (which is required for both DNA replication and repair) followed a similar spatial and temporal pattern to p53. The UV irradiation did not induce a mitotic response or the replication-associated antigens DNA polymerase alpha or Ki67. The accumulation of high levels of p53 and PCNA in response to UV doses to which many human populations are routinely exposed provides strong support for a model in which normal p53 acts as part of the DNA damage response in vertebrate cells. Such a model is consistent with the profound tumour-suppressor function of the p53 gene, the high rate of p53 mutation in neoplasia and the exceptionally high tumour susceptibility of p53-deficient mice.

Gadd45 is a nuclear cell cycle regulated protein which interacts with p21Cip1.

GADD45 was originally identified as a cDNA clone induced by growth arrest and DNA damage. We show that Gadd45 is a nuclear protein, widely expressed in normal tissues, particularly in quiescent cellular populations. Using cell synchronisation methods we show that Gadd45 levels are highest in the G1 phase of the cell cycle, and are greatly reduced during S phase. Immunoprecipitation of Gadd45 from mammalian cells reveals that it is tightly associated with a protein which reacts with antibodies to the cyclin dependent kinase inhibitor p21Cip1. Binding of recombinant Gadd45 protein to overlapping p21Cip1 peptides in ELISA assays and use of the yeast two hybrid assay show that Gadd45 directly interacts with this cell cycle inhibitor. These data suggest that Gadd45 may act in the regulation of the cell cycle. It is postulated that the interactions of Gadd45 with both p21Cip1 and PCNA are important for the modulation of cell cycles, and for the inhibition of DNA replication.

The p53 response to ionising radiation in adult and developing murine tissues.

The induction of the p53 response to ionising radiation has been studied during murine development and in the adult animal. The response has been assessed by precise quantitative assay of p53 protein levels in tissues and by immunohistochemistry. Newly developed transgenic mice in which a lacZ transgene is driven by a p53 response element have also been used to directly assess the transcriptional activity of the induced protein. There is striking developmental control of the p53 response so that in early development all tissues accumulate high levels of p53 following radiation and indeed p53 is present at elevated levels in some unirradiated tissues. Later in development clear heterogeneity of the p53 response becomes apparent, both in terms of the responses of individual tissues and of cell populations, within those tissues. The study of lacZ transgene expression and the occurrence of apoptosis in different tissues that accumulate p53 protein point to a further level of control regulating the nature and degree of the downstream response to elevated levels of p53 in cells. These findings have important implications for the susceptibility of different tissue types to carcinogenic and other insults. The early expression of the p53 response is consistent with novel models of p53 function that suggest it may have evolved principally as a defense against teratogenic insult that permits plasticity of development.

Expression of basic and acidic fibroblast growth factors and their receptor in normal and atherosclerotic human arteries.

OBJECTIVE: Acidic and basic fibroblast growth factors (FGF) are potent mitogens for vascular endothelial and smooth muscle cells and also promote angiogenesis. Given that atheroma is associated with the proliferation of a range of cell types, including smooth muscle cells, it has been proposed that these growth factors may play a part in the genesis and/or maintenance of atheromatous lesions. The aim of our study was to examine the distribution of acidic and basic FGF and their known receptor, fibroblast growth factor receptor 1 (FGFR-1), in normal and atherosclerotic arteries. METHODS: Formalin fixed was embedded archival material from a wide range of vessels was examined using a three stage avidin-biotin immunoperoxidase technique and specific polyclonal antibodies to acidic and basic FGF and FGFR-1. RESULTS: In normal arteries basic FGF immunoreactivity was found in medial smooth muscle cells and adventitial blood vessels, the luminal endothelium being non-reactive. Acidic FGF expression was observed predominantly in adventitial fibroblasts, while FGFR-1 expression was confined to the adventitial microvasculature. In early, simple, and advanced lesions acidic and basic FGF were expressed in macrophages and smooth muscle cells, the principal cell types involved in atherosclerotic lesion formation. Increased expression of basic FGF and FGFR-1 was particularly associated with neovascularisation of the atheromatous lesions. CONCLUSIONS: Acidic and basic FGF are expressed in early, simple and advanced atherosclerotic plaques. This suggests that in vivo these growth factors may have a role in the genesis of this disease. Basic FGF and FGFR-1 may potentially be involved in plaque neovascularisation. Such FGF driven angiogenic events may be central to the life threatening complications of atheroma and provide new options for therapeutic intervention.

Assessing apoptosis: a critical survey.

Much progress has been made in the understanding of the process of apoptosis and there is a burgeoning literature pointing to it being a key phenomenon in tissue homeostasis. Moreover it is clear that derangements of the apoptotic cascade and its regulation can occur in a variety of disease states including in cancer. Many methods exist for the demonstration of apoptosis but some are not quantifiable. Others, such as enumeration of apoptotic bodies or end-labelling techniques, lend themselves to quantification. However, poor methods of quantification are sometimes employed. In this review, the methodological problems that can affect the assessment of apoptosis are discussed and suggestions made for more rigorous approaches.

Gadd45 mutations are uncommon in human tumour cell lines.

GADD45 is an evolutionarily conserved gene that encodes a small acidic, nuclear protein and is an example of a p53 responsive gene. Gadd45 protein has been shown to interact with PCNA and also p21waf1. It has been implicated in growth arrest, DNA repair, chromatin structure and signal transduction. The confusing biochemical data has been clarified by the demonstration that Gadd45 null mice have a phenotype strikingly similar to that of p53 null mice, being tumour prone and showing marked genomic instability. We have tested the hypothesis that mutations in the GADD45 coding region might substitute for p53 abnormalities in tumour cell lines where p53 is wild type. After generating cDNA from mRNA in a panel of 24 cell lines we sequenced the GADD45 cDNA and have demonstrated that no mutations can be observed, even in the p53 wild type cell lines. Such data suggest that Gadd45 mutations are uncommon in human cancer. From this we postulate that, despite the phenotype of the GADD45 null mouse, GADD45 is unlikely to be the key mechanistic determinant of the tumour suppressor activity of the p53 pathway.

An inter-observer and intra-observer variability study on the diagnosis of lymph node biopsy specimens.

One hundred lymph node biopsy specimens were examined on two separate occasions by seven pathologists differing in experience in lymphoreticular pathology. Neither history nor immunohistochemistry was provided and the study, therefore, focused on morphological interpretation alone. The participants evaluated each case using a constructed response form in which the confidence with which they entered each response was also entered. Agreement on various points, between pathologists, between the two rounds, and with the referring centre was assessed. Whilst there was a high level of agreement over a diagnosis of benign vs. malignant and non-Hodgkin lymphoma vs. Hodgkin's disease, there was considerably less agreement over both T vs. B cell phenotype and high vs. low grade. The lack of agreement over grade, an evaluation which is usually made independent of immunohistochemistry, is particularly important, because of the relevance to selection of treatment. Proliferation markers may be more appropriate determinants of treatment choice.

Multicentric reticulohistiocytosis. Detailed immunophenotyping confirms macrophage origin.

A case study of multicentric reticulohistiocytosis is presented with extensive immunohistochemical studies of the infiltrate in both paraffin and cryostat sections. These studies showed that the cells are of monocyte/macrophage origin. B- and T-cell gene rearrangement analysis of multicentric reticulohistiocytosis was also performed and showed a germline configuration.

The Trp53 pathway is induced in vivo by low doses of gamma radiation.

The induction of the Trp53 response after very low doses (0.01-1 Gy) of ionizing radiation was studied in the adult mouse using immunochemical and immunohistochemical methods. We found a detectable response at 0.01 Gy and an increased induction of Trp53 with increasing dose in both radiation-resistant and radiation-sensitive tissues. These results suggest that there is no lower threshold for induction. This response was heterogeneous, since cells that received the same dose had different staining intensities, suggesting that the induction of Trp53 is not based simply on dose-dependent responses to DNA damage. These data also demonstrate the exquisite sensitivity of the Trp53 pathway and show that this response is controlled by cell- and tissue-specific factors that have yet to be defined.

Comparison of manual data coding errors in two hospitals.

The routine manual encoding of pathological data, using the SNOP and SNOMED systems at two London teaching hospitals, was reviewed. The error rates in the two departments were compared and the causes analysed. The relative merits of SNOP and SNOMED were considered. Methods to optimise the efficiency of manual encoding are suggested and the importance of accuracy in coding is emphasised.

Value of CD15 immunostaining in diagnosing Hodgkin's disease: a review of published literature.

The role of antibodies of CD15 as diagnostic markers of Hodgkin's disease was assessed from a review of the literature. A total of 571 cases of Hodgkin's disease and 386 cases of non-Hodgkin's lymphoma were included. The sensitivity of CD15 in detecting cases of Hodgkin's disease was 80% or 91% if cases of lymphocyte predominant Hodgkin's disease were excluded. The specificity of CD15 was only 80.6%, or in other words, 19.4% of cases of non-Hodgkin's lymphoma were CD15 positive. In an ideal test both the sensitivity and specificity would be 100% and if the test performance were no better than chance then they would both be 50%. It is concluded that CD15 immunostaining cannot be regarded as a sensitive or specific marker of Hodgkin's disease. Application of this formal method of analysis to other immunohistological reagents and panels of antibodies is discussed.

Immunohistochemistry in district general hospitals in England and Wales.

The findings of a survey on the use of immunohistochemistry in district general hospitals in England and Wales are reported. Immunohistochemistry is used in most district hospitals, contributes to the accuracy and objectivity of some histopathological diagnoses, and is considered to be generally useful though not without drawbacks. Its expansion is being hindered by lack of funds for reagents and staff. In a few regions attempts are being made to rationalise expenditure and coordinate development of the service. We believe that if this can be done at a regional or national level then the relatively small cost entailed will be justified by a resulting improvement in the quality of patient care.

Extraction of DNA from small sections of frozen tissue with simultaneous histological examination.

Though analysis of small sections of biopsy material by molecular techniques permits increased sensitivity, it also requires accurate histological examination of the tissue in order to reduce sampling error. A technique for the extraction of DNA from small sections of frozen biopsy material with simultaneous histological examination from adjacent sections is described that may enhance the accuracy of characterisation of the tissue, particularly where there is focal variation. The quality of the DNA obtained enables a full range of molecular studies to be carried out.