Cultural perceptions of healthy weight in rural Appalachian youth

INTRODUCTION

Rates of overweight among US children have been rising over the past three decades. Changes in lifestyle behaviors, including dietary and physical activity habits, have been examined thoroughly to identify correlates of weight status in children. Youth in rural US Appalachia are at a disproportionately greater risk for obesity and related health complications. Inadequate physical activity and poor dietary habits are two primary causes of obesity that have been noted in West Virginia adolescents. Few existing data describes the decisional balance in performing lifestyle behaviors, nor the perceptions of these youth regarding their beliefs about weight. The purpose of this study was to identify the perceptions of a healthy weight in rural Appalachian adolescents.

METHODS

Ninth grade students were recruited from classroom presentations in four high schools throughout West Virginia. Interested parent-caregiver pairs returned forms to indicate interest in participation. Separate focus group interviews were conducted concurrently with adolescent and parents or caregivers to identify the cultural perceptions of a healthy weight. Questions were developed using grounded theory to explore how a healthy weight was defined, what factors dictate body weight, the perceived severity of the obesity issue, and the social or health ramifications of the condition. Verbatim transcripts were analyzed to identify dominant themes, and content analysis provided text segments to describe the themes. This article describes the data obtained from the adolescent focus groups.

RESULTS

When asked what defined a healthy weight, the adolescents who participated in the focus groups placed great value on physical appearance and social acceptability. Students believed there was a particular number, either an absolute weight or body mass index value that determined a healthy weight. These numbers were usually conveyed by a physician; however, there was also a general acceptance of being 'thick' or a reliance on 'feeling healthy' as a determinant of maintaining a healthy weight. Despite these beliefs, many teens had unrealistic and unhealthy perceptions of weight. Female participants were more concerned with weight than males, some to the point of obsession. Both males and females expressed a social stigma associated with overweight. Issues of guilt and diminished self-esteem were prevalent. When asked about the extensiveness of the problem of childhood overweight, the students indicated that a degree of familiarity with being overweight has developed and 'you just get used to [seeing] it.' Because of the rising rates of chronic disease in this region, a fear was evident in these youth about the increased risk of developing these conditions in those who are overweight. Experiences with family members with diabetes and cardiovascular disease fueled these concerns, which instilled a fear of becoming overweight in many of the students. Many perceptions of healthy weight and appropriate body size were shaped by the media and entertainment industry. Additionally, some participants admitted to performing unsafe practices to reduce body mass, such as very low calorie diets or fasting.

CONCLUSIONS

Youth in rural Appalachia present similar perceptions about weight as other children; however, differences in perceived healthy lifestyle habits and a general acceptance of a higher average body weight present additional challenges to addressing the increasing problem of child overweight. Despite the relative isolation of many of these communities, the media has a profound impact on weight valuation that has been intertwined with school-based health education and cultural values of health. These data will provide valuable information for the development of obesity prevention programs in rural Appalachia.

Equine multinodular pulmonary fibrosis: a newly recognized herpesvirus-associated fibrotic lung disease

Pulmonary fibrosis and interstitial lung disease are poorly understood in horses; the causes of such conditions are rarely identified. Equine herpesvirus 5 (EHV-5) is a gamma-herpesvirus of horses that has not been associated with disease in horses. Pathologic and virologic findings from 24 horses with progressive nodular fibrotic lung disease associated with EHV-5 infection are described and compared with 23 age-matched control animals. Gross lesions consisted of multiple nodules of fibrosis throughout the lungs. Histologically, there was marked interstitial fibrosis, often with preservation of an "alveolar-like" architecture, lined by cuboidal epithelial cells. The airways contained primarily neutrophils and macrophages. Rare macrophages contained large eosinophilic intranuclear viral inclusion bodies; similar inclusion bodies were also found cytologically. The inclusions were identified as herpesviral-like particles by transmission electron microscopy in a single horse. In situ hybridization was used to detect EHV-5 nucleic acids within occasional macrophage nuclei. With polymerase chain reaction (PCR), the herpesviral DNA polymerase gene was detected in 19/24 (79.2%) of affected horses and 2/23 (8.7%) of the control horses. Virus genera-specific PCR was used to detect EHV-5 in all of the affected horses and none of the control horses. EHV-2 was detected in 8/24 (33.3%) of affected horses and 1/9 (11.1%) of the control horses. This disease has not been reported before, and the authors propose that based upon the characteristic gross and histologic findings, the disease be known as equine multinodular pulmonary fibrosis. Further, we propose that this newly described disease develops in association with infection by the equine gamma-herpesvirus, EHV-5.

Genetic dissection of grain yield in bread wheat. I. QTL analysis

Grain yield forms one of the key economic drivers behind a successful wheat (Triticum aestivum L.) cropping enterprise and is consequently a major target for wheat breeding programmes. However, due to its complex nature, little is known regarding the genetic control of grain yield. A doubled-haploid population, comprising 182 individuals, produced from a cross between two cultivars 'Trident' and 'Molineux', was used to construct a linkage map based largely on microsatellite molecular makers. 'Trident' represents a lineage of wheat varieties from southern Australia that has achieved consistently high relative grain yield across a range of environments. In comparison, 'Molineux' would be rated as a variety with low to moderate grain yield. The doubled-haploid population was grown from 2002 to 2005 in replicated field experiments at a range of environments across the southern Australian wheat belt. In total, grain yield data were recorded for the population at 18 site-year combinations. Grain yield components were also measured at three of these environments. Many loci previously found to be involved in the control of plant height, rust resistance and ear-emergence were found to influence grain yield and grain yield components in this population. An additional nine QTL, apparently unrelated to these traits, were also associated with grain yield. A QTL associated with grain yield on chromosome 1B, with no significant relationship with plant height, ear-emergence or rust resistance, was detected (LOD > or =2) at eight of the 18 environments. The mean yield, across 18 environments, of individuals carrying the 'Molineux' allele at the 1B locus was 4.8% higher than the mean grain yield of those lines carrying the 'Trident' allele at this locus. Another QTL identified on chromosome 4D was also associated with overall gain yield at six of the 18 environments. Of the nine grain yield QTL not shown to be associated with plant height, phenology or rust resistance, two were located near QTL associated with grain yield components. A third QTL, associated with grain yield components at each of the environments used for testing, was located on chromosome 7D. However, this QTL was not associated with grain yield at any of the environments. The implications of these findings on marker-assisted selection for grain yield are discussed.

Demonstrating ecological receptor health at contaminated sites with wild rodent sperm parameters

Consistently at Superfund and other contaminated terrestrial sites, ecological receptors have been chemically exposed for multiple decades by the time risk assessments are conducted. Given that numerous generations of the receptors have lived through the contaminated site condition by the present day, a paradigm shift from risk assessment, where the potential for health effects are forecasted, to a direct, health status assessment scheme for the site-exposed receptor, would seem to be most appropriate. We applied the only such existing direct health status assessment method, Rodent Sperm Analysis (RSA), with small rodents trapped at contaminated sites and at matched noncontaminated reference locations. Reproductive health, ecological risk assessment's endpoint of greatest concern, is targeted with RSA by comparing the sperm parameters of count, motility, and morphology, for each of which it is known how much of a change from a control condition signifies compromised reproductive capability. Given that sperm parameter thresholds were not exceeded in maximally exposed receptors, the data suggest that in the general case, contaminated terrestrial sites do not need cleanups to afford health protection to ecological species, and particularly the larger, wider-ranging, higher trophic level species. Our findings suggest that RSA has the ability to consistently discriminate between clean and contaminated sites, and that the method can allow for as definitive determinations of terrestrial ecological receptor health as are possible, thereby facilitating early site clean-up decisions.

Pulmonary response to airway instillation of autologous blood in horses

REASONS FOR PERFORMING STUDY

Exercise-induced pulmonary haemorrhage (EIPH) occurs in the majority of horses performing strenuous exercise. Associated pulmonary lesions include alveolar and airway wall fibrosis, which may enhance the severity of EIPH. Further work is required to understand the pulmonary response to blood in the equine airways.

OBJECTIVES

To confirm that a single instillation of autologous blood into horse airways is associated with alveolar wall fibrosis, and to determine if blood in the airways is also associated with peribronchiolar fibrosis.

METHODS

Paired regions of each lung were inoculated with blood or saline at 14 and 7 days, and 48, 24 and 6 h before euthanasia. Resulting lesions were described histologically and alveolar and airway wall collagen was quantified.

RESULTS

The main lesion observed on histology was hypertrophy and hyperplasia of type II pneumocytes at 7 days after blood instillation. This lesion was no longer present at 14 days. There were no significant effects of lung region, treatment (saline or autologous blood instillation), nor significant treatment-time interactions in the amount of collagen in the interstitium or in the peribronchial regions.

CONCLUSION

A single instillation of autologous blood in lung regions is not associated with pulmonary fibrosis.

POTENTIAL RELEVANCE

Pulmonary fibrosis and lung remodelling, characteristic of EIPH, are important because these lesions may enhance the severity of bleeding during exercise. A single instillation of autologous blood in the airspaces of the lung is not associated with pulmonary fibrosis. Therefore the pulmonary fibrosis described in EIPH must have other causes, such as repetitive bleeds, or the presence of blood in the pulmonary interstitium in addition to the airspaces. Prevention of pulmonary fibrosis through therapeutic intervention requires a better understanding of these mechanisms.

Genetic dissection of grain yield in bread wheat. I. QTL analysis

Grain yield forms one of the key economic drivers behind a successful wheat (Triticum aestivum L.) cropping enterprise and is consequently a major target for wheat breeding programmes. However, due to its complex nature, little is known regarding the genetic control of grain yield. A doubled-haploid population, comprising 182 individuals, produced from a cross between two cultivars 'Trident' and 'Molineux', was used to construct a linkage map based largely on microsatellite molecular makers. 'Trident' represents a lineage of wheat varieties from southern Australia that has achieved consistently high relative grain yield across a range of environments. In comparison, 'Molineux' would be rated as a variety with low to moderate grain yield. The doubled-haploid population was grown from 2002 to 2005 in replicated field experiments at a range of environments across the southern Australian wheat belt. In total, grain yield data were recorded for the population at 18 site-year combinations. Grain yield components were also measured at three of these environments. Many loci previously found to be involved in the control of plant height, rust resistance and ear-emergence were found to influence grain yield and grain yield components in this population. An additional nine QTL, apparently unrelated to these traits, were also associated with grain yield. A QTL associated with grain yield on chromosome 1B, with no significant relationship with plant height, ear-emergence or rust resistance, was detected (LOD > or =2) at eight of the 18 environments. The mean yield, across 18 environments, of individuals carrying the 'Molineux' allele at the 1B locus was 4.8% higher than the mean grain yield of those lines carrying the 'Trident' allele at this locus. Another QTL identified on chromosome 4D was also associated with overall gain yield at six of the 18 environments. Of the nine grain yield QTL not shown to be associated with plant height, phenology or rust resistance, two were located near QTL associated with grain yield components. A third QTL, associated with grain yield components at each of the environments used for testing, was located on chromosome 7D. However, this QTL was not associated with grain yield at any of the environments. The implications of these findings on marker-assisted selection for grain yield are discussed.

Histological evaluation of the equine larynx after unilateral laser-assisted ventriculocordectomy

REASONS FOR PERFORMING STUDY

Trans-endoscopic laser surgery, such as unilateral laser-assisted ventriculocordectomy (LVC), has gained popularity in the treatment of RLN because a laryngotomy incision or general anaesthesia are not required. However, removal of the vocal fold and ventricle takes considerable laser energy and could cause collateral tissue damage, including injury to the adjacent laryngeal cartilages.

OBJECTIVES

To document the histological effects of laser surgery on laryngeal tissues in horses that have undergone LVC for the treatment of laryngeal hemiplegia (LH).

METHODS

Six horses were used: 4 with experimentally induced LH that had subsequently undergone LVC 6 months prior to euthanasia; and, 2 horses were used as controls. One of the control horses with naturally occurring LH was used to study the effect of neuropathy alone, whereas the other was subjected to euthanasia immediately following LVC to evaluate the acute effect of laser surgery. Using a band saw, each larynx was sectioned transversely at 5 mm intervals and evaluated histologically.

RESULTS

Acutely, LVC caused thermal damage to adjacent soft tissues but did not affect the histology of the laryngeal cartilages. Six months after LVC, laryngeal cartilages were histologically normal and there was squamous metaplasia of the repaired laryngeal mucosa, resulting in restitution of the mucosal integrity.

CONCLUSIONS

Using a diode laser in contact fashion at 20 W, LVC can be used to remove the laryngeal vocal fold and ventricle without causing laryngeal cartilage damage.

POTENTIAL RELEVANCE

Laryngeal chondritis is an unlikely consequence of LVC.

HIF-1 and NF-κB-mediated upregulation of CXCR1 and CXCR2 expression promotes cell survival in hypoxic prostate cancer cells

Hypoxic cancer cells are resistant to treatment, leading to the selection of cells with a more malignant phenotype. The expression of interleukin-8 (IL-8) plays an important role in the tumorigenesis and metastasis of solid tumors including prostate cancer. Recently, we detected elevated expression of IL-8 and IL-8 receptors in human prostate cancer tissue. The objective of the current study was to determine whether hypoxia increases IL-8 and IL-8 receptor expression in prostate cancer cells and whether this contributes to a survival advantage in hypoxic cells. IL-8, CXCR1 and CXCR2 messenger RNA (mRNA) expression in PC3 cells was upregulated in response to hypoxia in a time-dependent manner. Elevated IL-8 secretion following hypoxia was detected by enzyme-linked immunosorbent assay, while immunoblotting confirmed elevated receptor expression. Attenuation of hypoxia-inducible factor (HIF-1) and nuclear factor-kappaB (NF-kappaB) transcriptional activity using small interfering RNA (siRNA), a HIF-1 dominant-negative and pharmacological inhibitors, abrogated hypoxia-induced transcription of CXCR1 and CXCR2 in PC3 cells. Furthermore, chromatin-IP analysis demonstrated binding of HIF-1 and NF-kappaB to CXCR1. Finally, inhibition of IL-8 signaling potentiated etoposide-induced cell death in hypoxic PC3 cells. These results suggest that IL-8 signaling confers a survival advantage to hypoxic prostate cancer cells, and therefore, strategies to inhibit IL-8 signaling may sensitize hypoxic tumor cells to conventional treatments.

Bioreductive drugs: from concept to clinic

One of the key issues for radiobiologists is the importance of hypoxia to the radiotherapy response. This review addresses the reasons for this and primarily focuses on one aspect, the development of bioreductive drugs that are specifically designed to target hypoxic tumour cells. Four classes of compound have been developed since this concept was first proposed: quinones, nitroaromatics, aliphatic and heteroaromatic N-oxides. All share two characteristics: (1) they require hypoxia for activation and (2) this activation is dependent on the presence of specific reductases. The most effective compounds have shown the ability to enhance the anti-tumour efficacy of agents that kill better-oxygenated cells, i.e. radiation and standard cytotoxic chemotherapy agents such as cisplatin and cyclophosphamide. Tirapazamine (TPZ) is the most widely studied of the lead compounds. After successful pre-clinical in vivo combination studies it entered clinical trial; over 20 trials have now been reported. Although TPZ has enhanced some standard regimens, the results are variable and in some combinations toxicity was enhanced. Banoxantrone (AQ4N) is another agent that is showing promise in early phase I/II clinical trials; the drug is well tolerated, is known to locate in the tumour and can be given in high doses without major toxicities. Mitomycin C (MMC), which shows some bioreductive activation in vitro, has been tested in combination trials. However, it is difficult to assign the enhancement of its effects to targeting of the hypoxic cells because of the significant level of its hypoxia-independent toxicity. More specific analogues of MMC, e.g. porfiromycin and apaziquone (EO9), have had variable success in the clinic. Other new drugs that have good pre-clinical profiles are PR 104 and NLCQ-1; data on their clinical safety/efficacy are not yet available. This paper reviews the pre-clinical data and discusses the clinical studies that have been reported.

A paradigm for the molecular identification of Mycobacterium species in a routine diagnostic laboratory

The aim of this study was to improve the identification ofMycobacteriumspecies in the context of a UK teaching hospital. Real-time PCR assays were established to enable the rapid differentiation betweenMycobacterium tuberculosis(MTB) complex andMycobacteriumspecies other thantuberculosis(MOTT), followed by 16S rRNA gene sequencing for the speciation of MOTT. Real-time PCR assays gave comparable results to those from the reference laboratory. The implementation of these PCR assays using an improved bead extraction method has enhanced the mycobacterial diagnostic service at the Royal Free Hospital by providing a rapid means of differentiating between MTB complex and MOTT, and would be simple to implement in similar laboratories. Sequence analysis successfully identified a range ofMycobacteriumspp. representative of those encountered in the clinical setting of the authors, includingMycobacterium aviumcomplex,Mycobacterium fortuitumgroup,Mycobacterium chelonae–Mycobacterium abscessusgroup,Mycobacterium xenopiandMycobacterium gordonae. It provides a useful tool for the identification of MOTT when clinically indicated.

Prothrombotic factors enhance heparin-induced thrombocytopenia and thrombosis in vivo in a mouse model

BACKGROUND

Heparin-induced thrombocytopenia/thrombosis (HIT/T) is a common cause of life- and limb-threatening thrombosis. The development of antibodies that react with complexes of heparin and platelet factor 4 (PF4) is fundamental to the development of the disease. However, anti-PF4/heparin antibodies are far more common than is HIT/T and there is less understanding of the factors that contribute to thrombosis in only a subset of patients.

OBJECTIVES

Both qualitative and quantitative differences in multiple factors (e.g. antibodies, heparin and platelets) may influence the clinical course of patients who develop anti-PF4/heparin antibodies. We examined the hypothesis that host-specific factors, such as comorbid prothrombotic conditions, would exacerbate the pathologic effects of anti-PF4/heparin antibodies.

METHODS AND RESULTS

A mouse model transgenic for human Fcgamma RIIa and PF4 and null for mouse PF4 was used to study the influence of prothrombotic conditions on the effects of anti-PF4/heparin antibodies in vivo. To simulate a prothrombotic milieu, mice were fed a hypercholesterolemic diet (HD). HD-fed mice had elevated plasma cholesterol, increased platelet reactivity and increased endothelial activation relative to mice fed a standard diet (SD). Age- and sex-matched mice from each diet group were treated with an anti-PF4/heparin antibody and heparin. HD-fed mice developed more severe thrombocytopenia than similarly treated SD-fed mice. Mice with moderate to severe thrombocytopenia had elevated plasma levels of thrombin-antithrombin complexes, indicative of increased thrombin generation in vivo. Platelet-fibrin thrombi were observed in multiple organs of HD-fed mice that developed severe thrombocytopenia.

CONCLUSIONS

Host-specific factors, such as prothrombotic changes in platelet reactivity and/or endothelial activation, may influence the development of thrombosis in a subset of patients who develop anti-PF4/heparin antibodies.

Mapping of a novel QTL for resistance to cereal cyst nematode in wheat

Cereal cyst nematode (CCN; Heterodera avenae Woll.) is a root pathogen of cereals that can cause severe yield losses in intolerant wheat cultivars. Loci for resistance to CCN, measured by a seedling bioassay, were identified by creating a genetic map based on a Trident/Molineux doubled haploid population of 182 lines. A novel locus accounting for up to 14% of the resistance to CCN was mapped to chromosome 1B of Molineux by association with microsatellite marker loci Xwmc719 and Xgwm140. This locus acts additively with the previously identified CCN resistance loci identified on chromosomes 6B (Cre8) and 2A (Cre5 on the VPM1 segment) in this population to explain 44% of the genetic variance for this major wheat pathogen.

Novel chimeric gene promoters responsive to hypoxia and ionizing radiation

Despite being an adverse prognostic factor in radiotherapy, hypoxia represents a physiological difference that can be exploited for selective cancer gene therapy. In this study gene therapy vectors responsive to both hypoxia and ionizing radiation (IR) were developed. Gene expression was regulated by novel, synthetic promoters containing hypoxia responsive elements (HREs) from the erythropoietin (Epo), the phosphoglycerate kinase 1 (PGK1) and the vascular endothelial growth factor (VEGF) genes, and IR-responsive CArG elements from the early growth response (Egr) 1 gene. All chimeric promoters could be activated by hypoxia and/or IR-treatment, and selectively control marker gene expression in human T24 bladder carcinoma and MCF-7 mammary carcinoma cells. Importantly, enhancers containing combinations of HREs and CArG elements were able to respond to both triggering treatments, with the Epo HRE/CArG combination proving to be the most responsive and robust. The Epo HRE/CArG enhancer could effectively control a suicide gene therapy strategy by selectively sensitizing hypoxic and/or irradiated cells expressing the enzyme horseradish peroxidase (HRP) to the prodrug indole-3-acetic acid (IAA). These data indicate that the use of such chimeric promoters may effectively regulate therapeutic gene expression within the tumor microenvironment in gene therapy strategies aimed at addressing the problem of hypoxia in radiotherapy.

Oxygen-sensitive enzyme-prodrug gene therapy for the eradication of radiation-resistant solid tumours

Overwhelming clinical and experimental data demonstrate that tumour hypoxia is associated with aggressive disease and poor treatment outcome as hypoxic cells are refractive to radiotherapy and some forms of chemotherapy. However, hypoxia is rare in physiologically normal tissues representing a tumour-specific condition. To selectively target this therapeutically refractive cell population, we have combined bioreductive chemotherapy with hypoxia-directed gene therapy. We have transfected the human fibrosarcoma cell line, HT1080, with a hypoxia-regulated expression vector encoding the human flavoprotein cytochrome c P450 reductase (HRE-P450R). This conferred hypoxia-dependent sensitivity to the alkylating nitroimidazole prodrug RSU1069 in vitro, with a greater than 30-fold increase in oxic/hypoxic cytotoxicity ratio compared with controls. Xenografts of both the HRE-P450R and empty vector transfectants had comparable hypoxic fractions and were refractive to single dose radiotherapy of up to 15 Gy. However, combining a prodrug of RSU1069 with a reduced radiotherapy dose of 10 Gy represents a curative regimen (50% tumour-free survival; day 100) in the HRE-P450R xenografts. In complete contrast, 100% mortality was apparent by day 44 in the empty vector control xenografts treated in the same way. Thus, an oxygen-sensitive gene-directed enzyme prodrug therapy approach may have utility when incorporated into conventional radiotherapy and/or chemotherapy protocols for loco-regional disease in any tissue where hypoxia is a contra-indication to treatment success. doi:10.1038/sj.gt.3301702

The level and species of plasma non-esterified fatty acids are not related to elevated plasma apolipoprotein B levels in familial combined hyperlipidemia

Familial combined hyperlipidemia (FCHL), the leading cause of familial hyperlipidemia with premature coronary artery disease, has been associated with insulin resistance and elevated plasma levels of apolipoproten B (apoB) and non-esterified fatty acids (NEFA). Becaus dietary fats affect plasma cholesterol levels, and specific saturated fatty acids (FA) are particularly potent stimulators in vitro of apoB secretio from hepatocytes, we hypothesized that FCHL patients would exhibit elevations in plasma levels of total FA or specific saturated species. Five families containing 12 FCHL subjects (5 adults, 7 children and 8 normals (5 adults, 3 children) were assessed by dietary, anthropometric, and plasma measurements (glucose, insulin, lipoproteins, total NEFA, and specific FA types). After adjustment of the data for age, gender, and family affiliation, multivariate ANOVA indicated that FCHL was significantly associated with elevated plasma levels of apoB (p = 0.001) and insulin (p< 0.001) and increased body weight (p=0.043). Nevertheless, dietary intakes of total and saturated fat were comparable in the two groups, as were plasma levels of total NEFA and the major saturated species. In a study population possessing the salient features of FCHL, circulating total NEFA were not elevated, nor were specific saturated NEFA that had been associated with apoB oversecretion in vitro. Despite the speculated link between plasma FA and apoB overproduction in FCHL, our data suggest that other metabolic factors underlie this disease.

ZD1839 ('Iressa'), a specific oral epidermal growth factor receptor-tyrosine kinase inhibitor, potentiates radiotherapy in a human colorectal cancer xenograft model

The effect of ZD1839 ('Iressa'), a specific inhibitor of the tyrosine kinase activity of the epidermal growth factor receptor, on the radiation response of human tumour cells (LoVo colorectal carcinoma) was evaluated in vitro and in vivo. ZD1839 (0.5 microM, incubated days 1-5) significantly increased the anti-proliferative effect of fractionated radiation treatment (2 Gy day(-1), days 1-3) on LoVo cells grown in vitro (P=0.002). ZD1839 combined with either single or fractionated radiotherapy in mice bearing LoVo tumour xenografts, also produced a highly significant increase in tumour growth inhibition (P< or = 0.001) when compared to treatment with either modality alone. The radio-potentiating effect of ZD1839 was more apparent when radiation was administered in a fractionated protocol. This phenomenon may be attributed to an anti proliferative effect of ZD1839 on tumour cell re-population between radiotherapy fractions. These data suggest radiotherapy with adjuvant ZD1839 could enhance treatment response. Clinical investigation of ZD1839 in combination with radiotherapy is therefore warranted.

17beta-Oestradiol treatment modulates nitric oxide synthase activity in MDA231 tumour with implications on growth and radiation response

The putative oestrogen receptor negative human breast cancer cell line MDA231, when grown as tumours in mice continually receiving 17beta-oestradiol, showed substantially increased growth rate when compared to control animals. Further, we observed that 17beta-oestradiol treatment could both increase the growth rate of established MDA231 tumours as well as decreasing the time taken for initiating tumour growth. We have also demonstrated that this increase in growth rate is accompanied by a four-fold increase in nitric oxide synthase activity, which was predominantly the inducible form. Inducible-nitric oxide synthase expression in these tumours was confirmed by immunohistochemical analysis and appeared localized primarily in areas between viable and necrotic regions of the tumour (an area that is presumably hypoxic). Prophylactic treatment with the nitric oxide synthase inhibitor nitro-L-arginine methyl ester resulted in significant reduction in this apparent 17beta-oestradiol-mediated growth promoting effect. Tumours derived from mice receiving 17beta-oestradiol-treatment were characterized by a significantly lower fraction of perfused blood vessels and an indication of an increased hypoxic fraction. Consistent with these observations, 17beta-oestradiol-treated tumours were less radio-responsive compared to control tumours when treated with a single radiation dose of 15 Gy. Our data suggests that long-term treatment with oestrogen could significantly alter the tumour oxygenation status during breast tumour progression, thus affecting response to radiotherapy.

Bioreductive and gene therapy approaches to hypoxic diseases

Hypoxia is a feature that exists in most, if not all, solid tumours and hypoxia has been shown to exist in a variety of other diseases. Bioreductive prodrugs have been developed to preferentially target the hypoxic cells in tumours. They are prodrugs, that are reductively activated (catalysed by reductive enzymes) to afford their active (toxic) species. More recently, bioreductive delivery agents that "release" a therapeutic entity preferentially under hypoxic conditions have also been developed to target hypoxia, not only in tumours, but also in a host of other diseases. This new technology platform is described in this review. In addition, we discuss the potential of utilising hypoxia to deliver selective gene therapy based upon the transcription factor HIF-1 and the use of unique genetic sequences termed HRE's (hypoxia responsive elements) that specifically control gene expression under hypoxic conditions. Finally, we describe how these drugs and gene-based therapeutic approaches can be combined to potentially deliver a highly selective form of therapy for cancer and other diseases where hypoxia plays a major pathophysiological role.

Arterial wall chondroitin sulfate proteoglycans: diverse molecules with distinct roles in lipoprotein retention and atherogenesis

Chondroitin sulfate proteoglycans (CSPGs) of the arterial wall are generally considered to be atherogenic because of their ability to trap cholesterol-rich lipoproteins in vitro. Nevertheless, CSPGs are a diverse group of molecules with a long evolutionary history and distinct biologic functions. The three principal CSPGs in the arterial wall are versican, which is part of the hyalectan gene family; and decorin and biglycan, which are members of a separate gene family, the small leucine-rich proteoglycans. Importantly, there is now substantial evidence that the different molecular species of CSPGs participate unequally in lipoprotein retention, and that they exert unequal regulatory effects that are related to atherogenesis. Recently available murine models with genetic manipulations that affect CSPGs now allow causal studies of the roles of these molecules to be conducted in vivo, with occasionally surprising results. Moreover, tools are being developed to examine human genetic variations that are relevant to CSPGs, which may provide additional important insights into the human disease. The era in which proteoglycans are regarded as a nondescript backdrop, playing purely nonspecific structural roles, is over. Studies in manipulated animals and in human populations will continue to reveal precise, dynamic roles for these fascinating and ancient molecules.

The triple threat to nascent apolipoprotein B. Evidence for multiple, distinct degradative pathways

We previously showed that Omega-3 fatty acids reduce secretion of apolipoprotein B (apoB) from cultured hepatocytes by stimulating post-translational degradation. In this report, we now characterize this process, particularly in regard to the two known processes that degrade newly synthesized apoB, endoplasmic reticulum (ER)-associated degradation and re-uptake from the cell surface. First, we found that Omega-3-induced degradation preferentially reduces the secretion of large, assembled apoB-lipoprotein particles, and apoB polypeptide length is not a determinant. Second, based on several experimental approaches, ER-associated degradation is not involved. Third, re-uptake, the only process known to destroy fully assembled nascent lipoproteins, was clearly active in primary hepatocytes, but Omega-3-induced degradation of apoB continued even when re-uptake was blocked. Cell fractionation showed that Omega-3 fatty acids induced a striking loss of apoB100 from the Golgi, while sparing apoB100 in the ER, indicating a post-ER process. To determine the signaling involved, we used wortmannin, a phosphatidylinositol 3-kinase (PI3K) inhibitor, which blocked most, if not all, of the Omega-3 fatty acid effect. Therefore, nascent apoB is subject to ER-associated degradation, re-uptake, and a third distinct degradative pathway that appears to target lipoproteins after considerable assembly and involves a post-ER compartment and PI3K signaling. Physiologic, pathophysiologic, and pharmacologic regulation of net apoB secretion may involve alterations in any of these three degradative steps.

Effects of providing and withholding postfitting fine-tuning adjustments on outcome measures in novice hearing aid users: a pilot study

This pilot study was designed to examine the effects of either providing or withholding subject-driven, postfitting electroacoustic changes (fine tuning) on hearing aid performance as measured by tests of speech recognition in noise, sound quality, and benefit. A group of adult first-time hearing aid users with moderate, high-frequency sensorineural hearing loss was studied over a 5-month postfitting period. Half of the group served as a control group; half constituted the treatment group. Treatment consisted of making as many postfitting electroacoustic manipulations as the participants' complaints/observations required. These adjustments were withheld from the control group individuals. Group performance differences were assessed using the COSI, two versions of the APHAB, a Satisfaction scale, a Sound Quality tool, and the SIN test. Analysis revealed no statistically significant differences in the control and treatment groups' performances or perceived benefit at any of the five postfitting test sessions. These data suggested that there was no measurable advantage to be derived from making postfitting frequency-gain adjustments of 10 dB or less to hearing aids with wide dynamic range compression fitted in the manner described in this article. Definitive studies of the effects of postfitting electroacoustic fine tuning must be undertaken.

Transmembrane and cytoplasmic domains of syndecan mediate a multi-step endocytic pathway involving detergent-insoluble membrane rafts

Syndecan heparan sulphate proteoglycans directly mediate a novel endocytic pathway. Using Chinese hamster ovary cells expressing the human syndecan 1 core protein or a chimaeric receptor, FcR-Synd, consisting of the ectodomain of the IgG Fc receptor Ia linked to the transmembrane and cytoplasmic domains of syndecan 1, we previously reported that efficient internalization is triggered by ligand clustering, requires intact actin microfilaments and tyrosine kinases, proceeds with a t(1/2) of approx. 1 h and is distinct from coated-pit pathways. We have now examined the involvement of cholesterol-rich, detergent-insoluble membrane rafts. On clustering, (125)I-labelled IgG bound to FcR-Synd rapidly became insoluble in cold Triton X-100, well before endocytosis. Insolubility of clustered FcR-Synd ligand did not require the syndecan ectodomain, linkage of the cytoplasmic tail to the cytoskeleton, or energy-dependent cellular metabolism. Pretreatment of cells with cyclodextrin to deplete cholesterol from rafts abolished insolubility of the clustered ligand and inhibited endocytosis in a dose-responsive fashion. Similar results were obtained with (125)I-labelled lipoprotein lipase bound to authentic cell-surface syndecan. In contrast, the 39 kDa receptor-associated protein (RAP), a coated-pit ligand, was more than 80% soluble in cold Triton even after internalization; cellular cholesterol depletion failed to substantially affect the internalization of (125)I-RAP. Overall, our results indicate a multi-step endocytic process consisting of ligand binding, clustering, energy-independent lateral movement into detergent-insoluble membrane rafts and finally recruitment of actin and tyrosine kinases to bring the ligands into the cell.