Adjuvant carboplatin and gemcitabine combination chemotherapy postamputation in canine appendicular osteosarcoma

BACKGROUND

Appendicular osteosarcoma (OSA), the most common bone tumor in dogs, is typically treated by amputation and adjuvant chemotherapy. Despite numerous efforts, the median survival time (MST) for dogs receiving a platinum compound, doxorubicin, or a combination of these remains at 8-12 months. Evidence from studies in mice suggests that gemcitabine has activity against OSA in vivo. Our preliminary work demonstrated that the addition of low-dosage (10 mM) gemcitabine to carboplatin resulted in synergistic inhibition of OSA cell viability in vitro.

OBJECTIVE

The purpose of the following study was to determine whether the addition of low-dosage (2 mg/kg) gemcitabine to carboplatin chemotherapy in dogs with OSA after amputation would improve MST over carboplatin monotherapy.

ANIMALS

Fifty dogs with histologically confirmed appendicular OSA.

METHODS

Dogs were treated prospectively with amputation and up to 4 dosages of carboplatin and gemcitabine in combination every 3 weeks.

RESULTS

The chemotherapeutic regimen was well tolerated with only 5 episodes of grade 3 or 4 hematologic toxicity. The median disease-free interval (DFI) was 203 days and the MST was 279 for all dogs in this study. The 1- and 2-year survival rates were 29.5 and 11.3%, respectively. Dogs with proximal humeral OSA had a shorter median DFI (P = .04) compared with dogs with OSA in other locations.

CONCLUSIONS AND CLINICAL IMPORTANCE

These results are comparable to those reported for carboplatin monotherapy indicating that the addition of gemcitabine to carboplatin in dogs with appendicular OSA does not appear to improve outcome.

Pro-inflammatory high-density lipoproteins and atherosclerosis are induced in lupus-prone mice by a high-fat diet and leptin

Atherosclerosis is accelerated in people with systemic lupus erythematosus, and the presence of dysfunctional, pro-inflammatory high-density lipoproteins is a marker of increased risk. We developed a mouse model of multigenic lupus exposed to environmental factors known to accelerate atherosclerosis in humans - high-fat diet with or without injections of the adipokine leptin. BWF1 mice were the lupus-prone model; BALB/c were non-autoimmune controls. High-fat diet increased total serum cholesterol in both strains. In BALB/c mice, non-high-density lipoprotein cholesterol levels increased; they did not develop atherosclerosis. In contrast, BWF1 mice on high-fat diets developed increased quantities of high-density lipoproteins as well as elevated high-density lipoprotein scores, indicating pro-inflammatory high-density lipoproteins; they also developed atherosclerosis. In the lupus-prone strain, addition of leptin increased pro-inflammatory high-density lipoprotein scores and atherosclerosis, and accelerated proteinuria. These data suggest that environmental factors associated with obesity and metabolic syndrome can accelerate atherosclerosis and disease in a lupus-prone background.

Characterization, expression and function of c-Met in canine spontaneous cancers

Aberrant expression of the proto-oncogene c-Met has been noted in a variety of human cancers. To better define the potential role of Met dysregulation in canine cancer, the canine Met, hepatocyte growth factor (HGF) and HGF activator were cloned. Inappropriate expression of Met was present in canine tumour cell lines derived from a wide variety of cancers. Furthermore, both HGF and HGF activator were also expressed in several of these cell lines, providing evidence of a possible autocrine loop of Met activation. Stimulation of tumour cell lines with recombinant human HGF induced Met autophosphorylation, as well as activation of the downstream signalling elements Gab-1, Akt and Erk1/2. Scattering of tumour cells and migration across a defect occurred in response to HGF stimulation. The Met inhibitor PHA665752 blocked both HGF-induced phosphorylation of canine Met and HGF-mediated cell cycling, scattering and migration. These studies provide evidence that Met dysregulation may play a role in the biology of canine cancer and lay the groundwork for future studies employing Met inhibitors.

Atherosclerosis and systemic lupus erythematosus: the role of altered lipids and of autoantibodies

The accelerated atherosclerosis that occurs in some patients with systemic lupus erythematosus (SLE) has a complex pathogenesis, including alterations in lipids, inflammation and the immune system. In this article, we review the evidence that peroxidase-related alteration of normal, protective high-density lipoprotein (HDL) converts them to pro-inflammatory HDL (piHDL), characterized by lower content of the cholesterol transport lipoprotein ApoA1 and impaired function of the antioxidant enzyme paroxonase, which prevents oxidation of low-density lipoprotein (LDL). Forty-five per cent of women with SLE have piHDL compared with 20% of patients with rheumatoid arthritis and 4% of healthy controls. The presence of piHDL increases risk for coronary artery events and carotid artery plaque. Another result of lipid oxidation in patients with SLE is generation of highly oxidized LDL and phospholipids (PL), probably stimulating antibodies to OxPL phospholipids. These antibodies along with promoting thrombosis also interfere with deposits of Annexin V onto endothelial cells, which probably promote increased instability of atherosclerotic plaque. Thus, piHDL and anti-OxPL promote plaque formation, plaque instability and thrombosis, accounting for some of the large increase in atherosclerosis and coronary artery events in SLE.

Confidentiality in psychological practice: A decrepit concept?

Although the principle of confidentiality in the relationship between psychologists and client has been vaunted, and is emphasised in the Australian Psychological Society's Code of Professional Conduct (the APS code; 1994), the confidentiality of this relationship is circumscribed by the absence of legal protections, the ethical beliefs of psychologists, institutional practices, and the provisions of the APS code itself. Lack of privilege in judicial proceedings, and statutory obligations to report certain types of behaviour, mandate breaches of confidentiality in some circumstances. Ethical beliefs of psychologists may support disclosure, especially where it is believed that there is danger of serious physical harm to the client or others. Multidisciplinary teams and institutional settings require the exchange of information for optimal delivery of services. Recent amendments to the APS code may require disclosure without the client's consent when a client is believed to be suicidal. Such developments, when considered at all, are typically regarded as exceptions to a general obligation of confidentiality. However, discussion of exceptions presupposes agreement on fundamental principle: the significance of, and rationale for, confidentiality in the psychologist-client relationship. It is argued in this paper that the obligation of confidentiality has been assumed rather than vigorously analysed and empirically explored. A critical examination of this obligation is the most appropriate starting point for the rehabilitation of contemporary principles of confidentiality in the psychologist-client relationship.

The challenge of patients' unmet palliative care needs in the final stages of chronic illness

BACKGROUND

There is consensus in the literature that the end of life care for patients with chronic illness is suboptimal, but research on the specific needs of this population is limited.

AIM

This study aimed to use a mixed methodology and case study approach to explore the palliative care needs of patients with a non-cancer diagnosis from the perspectives of the patient, their significant other and the clinical team responsible for their care. Patients (n = 18) had a diagnosis of either end-stage heart failure, renal failure or respiratory disease.

METHODS

The Short Form 36 and Hospital and Anxiety and Depression Questionnaire were completed by all patients. Unstructured interviews were (n = 35) were conducted separately with each patient and then their significant other. These were followed by a focus group discussion (n = 18) with the multiprofessional clinical team. Quantitative data were analysed using simple descriptive statistics and simple descriptive statistics. All qualitative data were taped, transcribed and analysed using Colaizzi's approach to qualitative analysis.

FINDINGS

Deteriorating health status was the central theme derived from this analysis. It led to decreased independence, social isolation and family burden. These problems were mitigated by the limited resources at the individual's disposal and the availability of support from hospital and community services. Generally resources and support were perceived as lacking. All participants in this study expressed concerns regarding the patients' future and some patients described feelings of depression or acceptance of the inevitability of imminent death.

CONCLUSION

Patients dying from chronic illness in this study had many concerns and unmet clinical needs. Care teams were frustrated by the lack of resources available to them and admitted they were ill-equipped to provide for the individual's holistic needs. Some clinicians described difficulty in talking openly with the patient and family regarding the palliative nature of their treatment. An earlier and more effective implementation of the palliative care approach is necessary if the needs of patients in the final stages of chronic illness are to be adequately addressed.

Expectations and preferences regarding confidentiality in the psychologist-client relationship

Two hundred and fifty-six members of the Australian public were surveyed regarding situations in which a psychologist might breach confidentiality and third parties to whom information might be disclosed. There was strong agreement between respondents' expectations about the way in which psychologists would act, and their preferences regarding how psychologists should act. While respondents supported confidentiality within the psychotherapeutic relationship, they clearly distinguished situations in which, and third parties to whom, disclosure could appropriately occur. Disclosure was expected and preferred when a client revealed a murder (planned or confessed), suicide plans, child abuse, or treason, and where the recipients of the information were colleagues of the psychologist or parents of a client younger than 13 years. Compared to nonparents, parents more strongly supported disclosure regarding illegal drug use and child abuse, and believed that parents should have access to a child's records. In general, respondents' view of the way in which psychologists should treat confidentiality issues were consistent with the guidelines prescribed by the Australian Psychological Society in the Code of Professional Conduct (1986).

Oncogenic BRAF regulates beta-Trcp expression and NF-kappaB activity in human melanoma cells

Mutational activation of BRAF is a frequent event in human malignant melanomas suggesting that BRAF-dependent signaling is conducive to melanoma cell growth and survival. Previously published work reported that melanoma cells exhibit constitutive anti-apoptotic nuclear factor kappaB (NF-kappaB) transcription factor activation triggered by proteolysis of its inhibitor IkappaB. IkappaB degradation is dependent upon its phosphorylation by the IkappaB kinase (IKK) complex and subsequent ubiquitination facilitated by beta-Trcp E3 ubiquitin ligase. Here, we report that melanocytes expressing a conditionally oncogenic form of BRAF(V600E) exhibit enhanced beta-Trcp expression, increased IKK activity and a concomitant increase in the rate of IkappaBalpha degradation. Conversely, inhibition of BRAF signaling using either a broad-spectrum Raf inhibitor (BAY 43-9006) or by selective knock-down of BRAF(V600E) expression by RNA interference in human melanoma cells leads to decreased IKK activity and beta-Trcp expression, stabilization of IkappaB, inhibition of NF-kappaB transcriptional activity and sensitization of these cells to apoptosis. Taken together, these data support a model in which mutational activation of BRAF in human melanomas contributes to constitutive induction of NF-kappaB activity and to increased survival of melanoma cells.

Identification of a novel germline MET mutation in dogs

The MET proto-oncogene encodes a transmembrane tyrosine kinase receptor that mediates multiple functions such as migration, cycling and survival by binding to hepatocyte growth factor (HGF). Dysregulation of MET through inappropriate expression or mutation has been shown to play an important role in human cancers. Furthermore, inherited mutations in MET are known to contribute to the development of gastric and renal cancer in humans. Lastly, mouse models of MET mutations lead to the development of a wide variety of cancers including lymphomas, sarcomas and some forms of carcinoma. In the process of cloning canine MET, a novel germline point mutation was found in the juxtamembrane domain (G966S) in two of the templates used for cloning, both of which were derived from Rottweiler dogs, a breed believed to be at high risk for the development of several cancers. Screening of germline DNA from a variety of breeds revealed that this mutation was present in approximately 70% of Rottweiler dogs and <5% of all other breeds examined, suggesting a breed-specific heritable mutation. Stable transfection of the G966S mutant form of MET into NIH3T3 cells resulted in enhanced baseline scattering and migration of the cells, which was further increased in the presence of HGF. This study supports the notion that particular dog breeds may carry germline mutations that contribute to high rates of cancer in a manner similar to heritable, cancer-associated mutations in humans.

A phase II study of celecoxib (C) with irinotecan (I), 5-fluorouracil (F), and leucovorin (L) in patients (pts) with advanced or metastatic colorectal cancer (CRC)

3588

Background: Expression of cyclooxygenase-2 (COX-2), present in most CRC, is associated with a worse prognosis. C, a selective COX-2 inhibitor, has inhibitory effects against CRC which appear at least additive with chemotherapy preclinically. A multi-institutional phase II trial was conducted to evaluate C plus standard IFL as first-line treatment for pts with incurable CRC. Methods: C 400mg po BID starting Day #1; I 125mg/m2 iv weekly starting Day #15; F 500mg/m2 iv bolus weekly starting Day #15; L 20mg/m2 iv weekly bolus starting Day #15. Patients received IFL for 4 weeks followed by a two-week rest. C was continued during the rest. Pts were treated until disease progression or unacceptable toxicity. Primary endpoint was response with planned sample size of 47 patients. Results: 47 pts were consented and treated. Evaluable pt characteristics: Male/female (no.) = 34/13; mean age = 59.7; ECOG PS 0/1/2 (no.) = 31/14/2; cancer stage locally-advanced/distant/unknown (no.) = 10/28/9. Due to concerns of risk of excess cardiovascular (CV) toxicity the protocol was amended halfway through enrollment to exclude pts with PS 2, and to require low-dose aspirin (ASA) for pts at high risk for CV events. Pre-and post-modification (mod) results are shown in the table . In general hematologic toxicity was moderate. Non-hematologic toxicity was mostly gastrointestinal, but 25% experienced cardiac or vascular toxicity (1 cardiac arrest, 1 MI, 1 CHF, 3 arrhythmias, 2 DVT, 2 CVA, 1 hyper- and 1 hypotension). All cardiac events occurred before modification of the protocol. There was 1 treatment-related death from cardiac arrest. Conclusions: C may be given safely with IFL chemotherapy, if pts are carefully selected. Addition of low-dose ASA may reduce cardiac toxicity. Post-mod TTP and survival for C plus IFL appear superior to historical results for IFL, but a phase III study would be required for confirmation.

[Table: see text]

[Table: see text]

A case of resistance to thyroid hormone without mutation in the thyroid hormone receptor beta

BACKGROUND

Resistance to Thyroid Hormone (RTH) is a condition caused by tissue hyposensitivity to the effects of circulating thyroid hormone, and may be misdiagnosed as hyperthyroidism.

AIMS

We report the first case of RTH in an Irish patient highlighting the clinical features and the pathophysiological mechanism underlying the characteristic laboratory abnormalities found in the condition.

METHODS

We describe an isolated case of RTH initially misdiagnosed as hyperthyroidism, and detail the investigations which ultimately led to the correct diagnosis. Genetic screening of the thyroid hormone receptor beta gene was performed.

RESULTS

Thyroid function tests including T3 suppression test and TRH-stimulation test suggested a diagnosis of RTH. Genetic testing failed to demonstrate a mutation in the thyroid hormone receptor.

CONCLUSION

RTH is a rare inherited condition that may be misdiagnosed as hyperthyroidism. The case we describe most likely results from a de novo mutation in an as yet undiscovered gene. RTH should be considered in patients with elevated thyroid hormone levels and normal TSH so that unnecessary and potentially harmful treatment can be avoided.

Perceptual indicators of environmental health, future land use, and stewardship

There are important linkages between the health of humans and the environment, restoration of degraded lands, and long-term stewardship of public lands, yet most environmental indicators deal only with assessing the physical and biological aspects of ecosystems. In this article, we examine the ratings of perceptions of several environmental problems for their utility as indicators of environmental quality, and examine perceptions of future land use by people interviewed in Santa Fe, New Mexico, near the Department of Energy's (DOE) Los Alamos National Laboratory (LANL). Overall, people with lower incomes rated environmental problems as more severe than others, were more willing to spend federal funds to solve them, and were consistent in their ratings of severity of environmental problems and their willingness to spend federal funds. Cleaning up LANL and other Department of Energy sites, received the highest rating for expenditure of federal funds. The highest rated future uses for DOE sites were for recreation and for National Environmental Research Parks. People with less education generally gave higher ratings to most future land uses for DOE than did those with more education. However, those with higher education gave higher ratings to nuclear reprocessing, and nuclear material storage. Where there were differences, the people interviewed at Santa Fe rated all environmental problems (except pesticides) as more severe than did those previously interviewed in Albuquerque (located farther from the LANL site), and they were more willing to spend federal funds on these problems. Ratings for all future land uses did not differ between the Santa Fe and Albuquerque respondents. These perception-based indicators show general agreement among people living close and farther away from LANL with respect to cleaning up LANL and the future land uses for the site. These indicators should be considered by regulators, site personnel, and policy makers in future management and land use decisions.

Differential effects of kinase cascade inhibitors on neoplastic and cytokine-mediated cell proliferation

The Raf/MEK/ERK and PI3K/Akt pathways regulate proliferation and prevent apoptosis, and their altered expression is commonly observed in human cancer due to the high mutation frequency of upstream regulators. In this study, the effects of Raf, MEK, and PI3K inhibitors on conditionally transformed hematopoietic cells were examined to determine if they would display cytotoxic differences between cytokine- and oncogene-mediated proliferation, and whether inhibition of both pathways was a more effective means to induce apoptosis. In the hematopoietic model system employed, proliferation was conditional and occurred when either interleukin-3 (IL-3) or the estrogen receptor antagonist 4-hydroxytamoxifen (4HT), which activates the conditional oncoprotein (DeltaRaf:ER), were provided. Thus, upon the addition of the signal transduction inhibitors and either IL-3 or 4HT, the effects of these drugs were examined in the same cell under 'cytokine-' and 'oncoprotein' -mediated growth conditions avoiding genetic and differentiation stage heterogeneity. At drug concentrations around the reported IC(50) for the Raf inhibitor L-779,450, it suppressed DNA synthesis and induced apoptosis in hematopoietic FDC-P1 cells transformed to grow in response to either Raf-1 or A-Raf (FD/DeltaRaf-1:ER and FD/DeltaA-Raf:ER), but it displayed less effects on DNA synthesis and apoptosis when the cells were cultured in IL-3. This Raf inhibitor was less effective on B-Raf- or MEK1-responsive cells, demonstrating the specificity of this drug. MEK inhibitors also suppressed DNA synthesis and induced apoptosis in Raf-responsive cells and the effects were more significant on Raf-responsive compared to cytokine-mediated growth. The PI3K inhibitor LY294002 suppressed Raf-mediated growth, indicating that part of the long-term proliferative effects mediated by Raf are PI3K dependent. Simultaneous inhibition of both Raf/MEK/ERK and PI3K/Akt pathways proved a more efficient means to suppress DNA synthesis and induce apoptosis at lower drug concentrations.

Requirement for the PI3K/Akt pathway in MEK1-mediated growth and prevention of apoptosis: identification of an Achilles heel in leukemia

The Raf/MEK/ERK kinase cascade plays a critical role in transducing growth signals from activated cell surface receptors. Using DeltaMEK1:ER, a conditionally active form of MEK1 which responds to either beta-estradiol or the estrogen receptor antagonist 4 hydroxy-tamoxifen (4HT), we previously documented the ability of this dual specificity protein kinase to abrogate the cytokine-dependency of human (TF-1) and murine (FDC-P1 and FL5.12) hematopoietic cells lines. Here we demonstrate the ability of DeltaMEK1:ER to activate the phosphatidylinositol 3-kinase (PI3K)/Akt/p70 ribosomal S6 kinase (p70(S6K)) pathway and the importance of this pathway in MEK1-mediated prevention of apoptosis. MEK1-responsive cells can be maintained long term in the presence of beta-estradiol, 4HT or IL-3. Removal of hormone led to the rapid cessation of cell proliferation and the induction of apoptosis in a manner similar to cytokine deprivation of the parental cells. Stimulation of DeltaMEK1:ER by 4HT resulted in ERK, PI3K, Akt and p70(S6K) activation. Treatment with PI3K, Akt and p70(S6K) inhibitors prevented MEK-responsive growth. Furthermore, the apoptotic effects of PI3K/Akt/p70(S6K) inhibitors could be enhanced by cotreatment with MEK inhibitors. Use of a PI3K inhibitor and a constitutively active form of Akt, [DeltaAkt(Myr(+))], indicated that activation of PI3K was necessary for MEK1-responsive growth and survival as activation of Akt alone was unable to compensate for the loss of PI3K activity. Cells transduced by MEK or MEK+Akt displayed different sensitivities to signal transduction inhibitors, which targeted these pathways. These results indicate a requirement for the activation of the PI3K pathway during MEK-mediated transformation of certain hematopoietic cells. These experiments provide important clues as to why the identification of mutant signaling pathways may be the Achilles heel of leukemic cell growth. Leukemia treatment targeting multiple signal transduction pathways may be more efficacious than therapy aimed at inhibiting a single pathway.

First Report of Silybum marianum as a Host of Puccinia punctiformis

Silybum marianum (L.) Gaertn. (milk thistle) is a problematic invasive weed in the western United States. The rust fungus, Puccinia punctiformis (F. Strauss) Rohl., is found throughout the world as a pathogen of Cirsium arvense (L.) Scop. (Canadian thistle). Recently, plants of S. marianum grown from surface-disinfested seeds in our quarantine greenhouse were parasitized by a rust. Apparently, an isolate of P. punctiformis collected from C. arvense in Turkey that was present in the greenhouse had spread to adjacent S. marianum plants and caused infection without applying any artificial dew period. Ribosomal internal transcribed spacer region sequences from fungal spore DNA isolated from the two hosts were identical. Initial signs on S. marianum were abundant, fragrant spermogonia on large leaves. These signs occur on secondary shoots of C. arvense and are indicative of systemic fungal infection (1). As the fungus infection developed on S. marianum, uredinia and urediniospores were produced. Sori on older leaves also produced teliospores. Urediniospores from infected leaves were harvested and sprayed uniformly on eight 17-day-old plants of S. marianum grown in isolation from P. punctiformis. The spore suspension consisted of 4 mg urediniospores suspended in 40 ml distilled water. Inoculated plants were incubated for 18 h in a dew chamber at 20°C in the dark and transferred to a greenhouse (20 to 25°C, 30 to 50% relative humidity, and natural light). After 13 days, uredia with urediniospores developed on four of the plants. Using the same procedure, inoculations were repeated on plants of S. marianum and S. eburneum Coss. & Durieu (the only other species described in the genus) with urediniospores of a domestic isolate of the fungus from C. arvense in Maryland. Of 51 inoculated plants of S. marianum, 23 became infected and produced uredinia. None of the 12 inoculated plants of S. eburneum showed symptoms of infection. In nature, C. arvense and S. marianum occupy different ecological areas. C. arvense is found predominately in humid temperate habitats, while S. marianum is found in habitats with a dry Mediterranean climate. Life cycles of each host are also different. C. arvense is a perennial that emerges in spring and dies back in winter, while S. marianum is a winter annual that emerges in fall and dies in late spring. Because of the differences in life cycles combined with the different geographical distribution, P. punctiformis from C. arvense may rarely encounter susceptible S. marianum plants in the field. Since fungal spores can be produced routinely on artificially inoculated plants, there might be potential to use P. punctiformis for biological control of S. marianum. To our knowledge, this is the first report of S. marianum as a host for P. punctiformis. Reference: (1) A. H. R. Buller. Puccinia sauveolens and its sexual process. Page 345 in: Researches on Fungi. Vol VII. The Sexual Process in the Uredinales, Toronto, Canada, 1950.

Exposure of South Carolinians to commercial meats and fish within their meat and fish diet

There has been considerable interest in the public's exposure to a variety of contaminants through the consumption of wild fish and game, yet there is little information on consumption of commercial meats and fish, or the relationship between commercial and self-caught fish. We conducted a dietary survey in 1999 to estimate exposure levels of 464 individuals from people attending the Palmetto Sportsmen's Classic. Mean consumption was similar for beef, chicken/turkey, and wild-caught fish, and much lower for pork and store-bought fish, and still lower for restaurant fish. There were no ethnic differences in the consumption of most commercial fish and meats, although the differences for chicken approached significance. There were significant ethnic differences in consumption of wild-caught fish. Women ate significantly less of all meat types, except store-bought fish. People over 45 ate less beef than younger people, and people younger than 32 ate significantly more chicken than others. There were no significant differences in consumption patterns as a function of income, except for chicken and wild-caught fish; people with higher incomes ate more chicken than others, and people with lower incomes ate more wild-caught fish than others. When all wild-caught and commercial fish and meats are considered, there are significant differences only for ethnicity and gender. Blacks consume significantly more fish than Whites, and men consume significantly more than women.

Molecular basis for the contribution of the antioxidant responsive element to cancer chemoprevention

This article provides an overview of the mechanisms by which cancer chemopreventive blocking agents increase the expression of detoxication and antioxidant genes. These agents all appear capable of transcriptionally activating a gene battery that includes NAD(P)H:quinone oxidoreductase, aldo-keto reductases, glutathione S-transferases, gamma-glutamylcysteine synthetase, glutathione synthetase and heme oxygenase. Gene induction occurs through the antioxidant responsive element (ARE), a process that is dependent on the Nuclear Factor-Erythroid 2p45-related factors, Nrf1 and Nrf2. Under basal conditions, these basic region leucine zipper (bZIP) transcription factors are located in the cytoplasm of the cell bound to Keap1, and upon challenge with inducing agents, they are released from Keap1 and translocate to the nucleus. Within the nucleus, Nrf1 and Nrf2 are recruited to the ARE as heterodimers with either small Maf proteins, FosB, c-Jun, JunD, activating transcription factor 2 (ATF2) or ATF4. The role of protein kinases in transducing chemical stress signals to the bZIP factors that affect gene induction through the ARE is discussed.

Role of the oncogenic Raf-1 in orchestration of discrete nuclear factor-kappaB-activating pathways

Raf-1, a key kinase in the Ras signaling pathway, plays critical roles in cell differentiation, proliferation, and tumorigenesis. However, knowledge of the Raf-1 in inflammation is limited. Using an inducible oncogenic Raf-1, we show that the Raf-1 orchestrates the discrete NF-kappaB activating pathways. While the Raf-1 activation induces a modest IkappaB degradation by enhancing the basal IkappaB kinase activity, it contradictorily suppresses the proinflammatory cytokine inducible IkappaB kinase complex, leading to an inhibition of TNF-alpha- and IL-1beta-induced NF-kappaB activation. Despite considerable degrees of overlap, LPS signaling is not affected by Raf-1. By either conditionally reducing Raf-1 activity or completely disrupting the Raf-1 signaling by PD98059, a specific inhibitor of MEK1, the otherwise inhibited cytokine responses can be restored. Moreover, when the activity of Raf-1 is up-regulated during the cell cycle progression from the G(0) phase to the late G(1) phase, the enhanced Raf-1 activity suffices to shift the TNF-alpha response from the sensitive to the insensitive state. Together, these studies elucidate a mechanism by which signaling outputs are shaped by the intracellular Raf-1, thus explaining the "cellular context"-dependent cytokine response.

Medico-legal knowledge of general practitioners: disjunctions, errors and uncertainties

This article discusses a survey of Victorian general practitioners which investigated doctors' legal knowledge, the impact of law on clinical practice, doctors' current medico-legal information sources and their legal education needs and preferences. Knowledge of legal standards was investigated in relation to three areas: disclosure of risk; ownership of, and access to, medical records; and proxy decision-making. Additionally, the impact of statutory reform in relation to proxy decision-making was explored. Further, doctors' past experience of medico-legal education, current sources of medico-legal information and preferences concerning future medico-legal information were explored. Results indicated that overall, respondents had a very inadequate understanding of relevant law and that relevant statutory standards have had little impact on clinical practice. Professional bulletins and journals were identified as major current legal information sources, whilst printed materials, seminars and conferences were preferred sources of legal information. The authors conclude that there is a significant disjunction between legal standards and doctors' awareness of those standards, thereby creating a significant source of liability for doctors. Results highlight an urgent need to develop legal education programs for general practitioners based on doctors' identified needs and preferences.

Role of the Raf signal transduction cascade in the in vitro resistance to the anticancer drug doxorubicin

The precise molecular events involved in the development of drug resistance (DR) remain largely unknown. Raf is an intermediate in the signal transduction cascades initiated by growth factors. The hypothesis behind the following studies is that deregulated Raf-1 expression plays a role in the development of drug resistance. A positive correlation was observed between increased Raf-1 activity and increased values for IC50 for doxorubicin in established cell lines. The National Cancer Institute/Adriamycin Resistant (NCI/ADR-RES) cell line exhibited both the highest Raf-1 activity and the highest IC50 values for doxorubicin (Adriamycin). In contrast, the MCF-7 cell line exhibited both lower Raf activity and lower IC50 values for doxorubicin. While MCF-7 cells transfected with either constitutively active DeltaRaf-1 or conditionally active DeltaRaf-1:AR demonstrated increased IC50 values for doxorubicin and a reduced capacity to undergo apoptosis after doxorubicin treatment as compared with parental cell lines. Moreover, growth curves performed show that both the constitutively and conditionally active forms of Raf-1 do not increase growth as compared with the parental MCF-7 cell line. This is important because it implies that higher cell counts between Raf transfectants and the parental MCF-7 cell line are attributable to differences in DR, not growth rates. These observations suggest a role for the Raf-1 protooncogene in the regulation of DR.

Formation of intracranial tumors by genetically modified human astrocytes defines four pathways critical in the development of human anaplastic astrocytoma

The formation of human malignant gliomas is thought to involve the accumulation of multiple genetic alterations. To define the function of specific alterations in glioma formation, we serially introduced genetic alterations functionally equivalent to those noted in human malignant gliomas into normal human astrocytes (NHAs). We then monitored the ability of each of these alterations to contribute to the growth of otherwise genetically stable NHAs into intracranial malignant gliomas. Using this model, we show that expression of human telomerase catalytic component (hTERT), but not E7-mediated inactivation of pRb or E6/E7-mediated inactivation of p53/pRb, was sufficient to initiate the tumorigenic process by circumventing cellular senescence in astrocytes. hTERT expression, even in combination with inactivation of p53/pRb, did not transform astrocytes. These alterations together, however, cooperated with ras pathway activation (initiated by expression of mutant H-Ras), but not with phosphatidylinositol 3-kinase pathway activation (initiated by expression of myristoylated Akt) or epidermal growth factor receptor activation, to allow for the formation of intracranial tumors strongly resembling p53/pRb pathway-deficient, telomerase-positive, ras-activated human grade III anaplastic astrocytomas. These results identify four pathways as key in the development of human anaplastic astrocytomas.

Effects of inducible MEK1 activation on the cytokine dependency of lymphoid cells

The Raf/MEK/MAP kinase cascade plays a critical role in transducing growth signals from activated cell surface receptors. Using deltaMEK1:ER, a conditionally active form of MEK1, we demonstrate the ability of this dual specificity protein kinase to abrogate the cytokine dependency of the murine lymphoid hematopoietic cell line FL5.12. Cytokine-independent cells were obtained from FL5.12 cells at a frequency of 1 x 10(-7), indicating that a low frequency of cells expressing deltaMEK1:ER were factor-independent. In general, cells that were converted to a cytokine-independent phenotype displayed a higher level of MAP kinase activity in response to deltaMEK1:ER activation than those that remained cytokine-dependent. deltaMEK1:ER-responsive cells could be maintained long-term in the presence of beta-estradiol, as well as the estrogen-receptor antagonist 4-hydroxy-tamoxifen. Removal of hormone led to the rapid cessation of cell growth in a manner similar to that observed when cytokine is withdrawn from the parental cells. GM-CSF mRNA transcripts were detected in the MEK1-responsive cells indicating that activated deltaMEK1:ER may induce a pathway leading to autocrine proliferation. Cytokine-dependent deltaMEK1:ER cells were found to increase the expression of GM-CSF receptor alpha (GM-CSFRalpha) in response to beta-estradiol. In contrast, MEK1-responsive cells were found to express constitutively lower levels of GM-CSFRalpha and beta common (betac) chains indicating that constitutive GM-CSF expression resulted in a decrease in GM-CSFR expression. Treatment of parental cells with supernatant from MEK1-responsive FL5.12 cells was sufficient to promote [3H]-thymidine incorporation. GM-CSF was found to enhance the viability of FL5.12 cells. The cell lines described here will be useful for elaborating the ability of the MAP kinase pathway to regulate cell proliferation in hematopoietic cells.

Reduction of aflatoxin B1 dialdehyde by rat and human aldo-keto reductases

Oxidation of the mycotoxin aflatoxin (AF) B1 yields the 8,9-epoxide, which nonenzymatically hydrolyzes rapidly to a dihydrodiol that in turn undergoes slow, base-catalyzed ring opening to a dialdehyde [Johnson, W. W., Harris, T. M., and Guengerich F. P. (1996) J. Am. Chem. Soc. 118, 8213-8220]. AFB1 dialdehyde does not bind to DNA but can react with protein lysine groups. One enzyme induced by cancer chemopreventive agents is AFB1 aldehyde reductase (AFAR), which catalyzes the NADPH-dependent reduction of the dialdehyde to a dialcohol. AFB1 dialdehyde is known to convert nonenzymatically to AFB1 dihydrodiol at neutral pH, and we reinvestigated the enzymatic reaction by preparing AFB1 dialdehyde at pH 10 and then used this to initiate reactions (at neutral pH) with rat and human AFAR isozymes. Two monoalcohols were identified as products, and their identities were established by NaB2H4 reduction, chemical cleavage, and mass spectrometry. The monoalcohol corresponding to reduction at C-8 formed first in reactions catalyzed by either the rat or the human AFAR. This C-8 monoalcohol was further reduced to AFB1 dialcohol by AFAR. The other monoalcohol (C-6a) was formed but not reduced to the dialcohol rapidly. Steady-state kinetic parameters were estimated for the reduction of AFB1 dialdehyde by rat and human AFAR to the monoalcohols. The apparent k(cat) and K(m) values were not adequate to rationalize the observed DeltaA(340) spectral changes in a kinetic model. Simulation fitting was done and yielded parameters indicative of greater enzyme efficiency. A survey of 12 human liver cytosol samples showed a variation of 2.3-fold in AFAR activity. Rats treated with AFB1 excreted the dialcohol and a monoalcohol in urine. The results of these studies are consistent with a role of (rat and human) AFAR in protection against AFB1 toxicity.

Dual growth arrest pathways in astrocytes and astrocytic tumors in response to Raf-1 activation

Normal human fibroblasts have been shown to undergo a p16(Ink4a)-associated senescence-like growth arrest in response to sustained activation of the Ras/Raf/MEK/ERK pathway. We noted a similar p16(Ink4a)-associated, senescence-like arrest in normal human astrocytes in response to expression of a conditional form of Raf-1. While HPV16 E7-mediated functional inactivation of the p16(Ink4a)/pRb pathway in astrocytes blocked the p16(Ink4a)-associated growth arrest in response to activation of Raf-1, it also revealed a second p21(Cip1)-associated, senescence-associated, beta-galactosidase-independent growth arrest pathway. Importantly, the p21(Cip1)-associated pathway was present not only in normal astrocytes but also in p53-, p14(ARF)-, and p16(Ink4a)/pRb-deficient high grade glioma cells that lacked the p16(Ink4a)-dependent arrest mechanism. These results suggest that normal human cells have redundant arrest pathways, which can be activated by Raf-1, and that even tumors that have dismantled p16(Ink4a)-dependent growth arrest pathways are potentially regulated by a second p21(Cip1)-dependent growth arrest pathway.

Induction of beta3-integrin gene expression by sustained activation of the Ras-regulated Raf-MEK-extracellular signal-regulated kinase signaling pathway

Alterations in the expression of integrin receptors for extracellular matrix (ECM) proteins are strongly associated with the acquisition of invasive and/or metastatic properties by human cancer cells. Despite this, comparatively little is known of the biochemical mechanisms that regulate the expression of integrin genes in cells. Here we demonstrate that the Ras-activated Raf-MEK-extracellular signal-regulated kinase (ERK) signaling pathway can specifically control the expression of individual integrin subunits in a variety of human and mouse cell lines. Pharmacological inhibition of MEK1 in a number of human melanoma and pancreatic carcinoma cell lines led to reduced cell surface expression of alpha6- and beta3-integrin. Consistent with this, conditional activation of the Raf-MEK-ERK pathway in NIH 3T3 cells led to a 5 to 20-fold induction of cell surface alpha6- and beta3-integrin expression. Induced beta3-integrin was expressed on the cell surface as a heterodimer with alphav-integrin; however, the overall level of alphav-integrin expression was not altered by Ras or Raf. Raf-induced beta3-integrin was observed in primary and established mouse fibroblast lines and in mouse and human endothelial cells. Consistent with previous reports of the ability of the Raf-MEK-ERK signaling pathway to induce beta3-integrin gene transcription in human K-562 erythroleukemia cells, Raf activation in NIH 3T3 cells led to elevated beta3-integrin mRNA. However, unlike immediate-early Raf targets such as heparin binding epidermal growth factor and Mdm2, beta3-integrin mRNA was induced by Raf in a manner that was cycloheximide sensitive. Surprisingly, activation of the Raf-MEK-ERK signaling pathway by growth factors and mitogens had little or no effect on beta3-integrin expression, suggesting that the expression of this gene requires sustained activation of this signaling pathway. In addition, despite the robust induction of cell surface alphavbeta3-integrin expression by Raf in NIH 3T3 cells, such cells display decreased spreading and adhesion, with a loss of focal adhesions and actin stress fibers. These data suggest that oncogene-induced alterations in integrin gene expression may participate in the changes in cell adhesion and migration that accompany the process of oncogenic transformation.

The health and welfare needs of female and transgender street sex workers in New South Wales

OBJECTIVES

To determine the health and welfare status of female and transgender street sex workers and their work-related experiences. Also to estimate population numbers, determine work locations, and identify the most appropriate education, health and welfare services for this group.

METHODS

Forty-eight street sex workers completed a questionnaire, mainly at their place of work. Demographic and sexual health profiles of sex workers attending the Sydney Sexual Health Centre and the Kirketon Road Centre in 1997 were compared with the street sample.

RESULTS

Up to 120 female and transgender sex workers worked on the streets in Sydney, Newcastle, Wollongong and surrounding areas in any one night: more than 80% of these were female. Of those sampled, fewer street workers than brothel sex workers (6% vs. 41%; p<0.001) were from non-English speaking backgrounds, and more (77% vs. 7%; p<0.0001) were currently injecting drugs. The street workers reported lower rates of condom use at work than local brothel workers (91.7% vs. 98.8%; p<0.016) and high rates of hepatitis B and C infection. Seventy-five per cent had experienced violence at work. Child care, lack of supportive relationships, community intolerance and low self-esteem were important problems for the street workers. While the police were frequently required by the community to move the street workers on, there were no reports of corrupt behaviour by police.

CONCLUSIONS

Health services need to specifically target this group with particular attention to the prevention of blood-borne virus infections, contraception, drug dependency and transgender issues. Consideration should be given to developing a network of safe houses to reduce community pressure and violence.

Analysis of the transcriptional program induced by Raf in epithelial cells

Activation of the Raf/MAP kinase pathway is a critical event in tumorigenesis induced by RAS and other oncogenes, a major role of this signaling system being the regulation of cellular transcription factors. To address the contribution of MAP kinase mediated transcriptional changes to the transformed phenotype, we used an inducible form of Raf to analyze early changes in the transcription of some 6000 genes following activation of the kinase in a normal human breast epithelial cell line. Of the more than 120 significant changes in mRNA level detected, genes promoting cell proliferation, invasiveness, and angiogenesis featured prominently. Some of the most strongly induced genes encoded growth factors of the EGF family: Autocrine activation of the EGF receptor was shown to be responsible for the ability of Raf activation to protect these cells from apoptosis induced by detachment of cells from extracellular matrix (anoikis), which is a critical component of the transformed phenotype.

The Cap'n'Collar basic leucine zipper transcription factor Nrf2 (NF-E2 p45-related factor 2) controls both constitutive and inducible expression of intestinal detoxification and glutathione biosynthetic enzymes

Northern blotting has shown that mouse small intestine contains relatively large amounts of the nuclear factor-E2 p45-related factor (Nrf) 2 transcription factor but relatively little Nrf1. Regulation of intestinal antioxidant and detoxication enzymes by Nrf2 has been assessed using a mouse line bearing a targeted disruption of the gene encoding this factor. Both Nrf2-/- and Nrf2+/+ mice were fed a control diet or one supplemented with either synthetic cancer chemopreventive agents [butylated hydroxyanisole (BHA), ethoxyquin (EQ), or oltipraz] or phytochemicals [indole-3-carbinol, cafestol and kahweol palmitate, sulforaphane, coumarin (CMRN), or alpha-angelicalactone]. The constitutive level of NAD(P)H:quinone oxidoreductase (NQO) and glutathione S-transferase (GST) enzyme activities in cytosols from small intestine was typically found to be between 30% and 70% lower in samples prepared from Nrf2 mutant mice fed a control diet than in equivalent samples from Nrf2+/+ mice. Most of the chemopreventive agents included in this study induced NQO and GST enzyme activities in the small intestine of Nrf2+/+ mice. Increases of between 2.7- and 6.2-fold were observed in wild-type animals fed diets supplemented with BHA or EQ; increases of about 2-fold were observed with a mixture of cafestol and kahweol palmitate, CMRN, or alpha-angelicalactone; and increases of 1.5-fold were measured with sulforaphane. Immunoblotting confirmed that in the small intestine, the constitutive level of NQO1 is lower in the Nrf2-/- mouse, and it also showed that induction of the oxidoreductase was substantially diminished in the mutant mouse. Immunoblotting class-alpha and class-mu GST showed that constitutive expression of most transferase subunits is also reduced in the small intestine of Nrf2 mutant mice. Significantly, induction of class-alpha and class-mu GST by EQ, BHA, or CMRN is apparent in the gene knockout animal. No consistent change in the constitutive levels of the catalytic heavy subunit of gamma-glutamylcysteinyl synthetase (GCS(h)) was observed in the small intestine of Nrf2-/- mice. However, although the expression of GCS(h) was found to be increased dramatically in the small intestine of Nrf2+/+ mice by dietary BHA or EQ, this induction was essentially abolished in the knockout mice. It is apparent that Nrf2 influences both constitutive and inducible expression of intestinal antioxidant and detoxication proteins in a gene-specific fashion. Immunohistochemistry revealed that induction of NQO1, class-alpha GST, and GCS(h) occurs primarily in epithelial cells of the small intestine. This suggests that the variation in inducibility of NQO1, Gsta1/2, and GCS(h) in the mutant mouse is not attributable to the expression of the enzymes in distinct cell types but rather to differences in the dependency of these genes on Nrf2 for induction.