Climatic modifiers of the response to nitrogen deposition in peat-forming Sphagnum mosses: a meta-analysis

Peatlands in the northern hemisphere have accumulated more atmospheric carbon (C) during the Holocene than any other terrestrial ecosystem, making peatlands long-term C sinks of global importance. Projected increases in nitrogen (N) deposition and temperature make future accumulation rates uncertain. Here, we assessed the impact of N deposition on peatland C sequestration potential by investigating the effects of experimental N addition on Sphagnum moss. We employed meta-regressions to the results of 107 field experiments, accounting for sampling dependence in the data. We found that high N loading (comprising N application rate, experiment duration, background N deposition) depressed Sphagnum production relative to untreated controls. The interactive effects of presence of competitive vascular plants and high tissue N concentrations indicated intensified biotic interactions and altered nutrient stochiometry as mechanisms underlying the detrimental N effects. Importantly, a higher summer temperature (mean for July) and increased annual precipitation intensified the negative effects of N. The temperature effect was comparable to an experimental application of almost 4 g N m(-2)  yr(-1) for each 1°C increase. Our results indicate that current rates of N deposition in a warmer environment will strongly inhibit C sequestration by Sphagnum-dominated vegetation.

Biomedical applications of hydroxyapatite nanoparticles

Nanotechnologies have the potential to improve current disease diagnosis due to their ability to circulate in the blood and distribute in the body to image tissues and cells or therapeutical applications to deliver a payload. Among nanoparticles with different materials composition, inorganic nanoparticles composed of calcium phosphate have numerous advantages including ease of synthesis, control of physico-chemical properties, strong interactions with their payload, and biocompatibility. In this review we discuss the different routes of synthesis of calcium phosphate nanoparticles, novel systems, strategies to load agents, biostability and cytotoxicity, biodistribution and pharmacokinetics, bio-imaging and therapeutical applications.

Propiconazole induces alterations in the hepatic metabolome of mice: relevance to propiconazole-induced hepatocarcinogenesis

Propiconazole is a mouse hepatotumorigenic fungicide and has been the subject of recent investigations into its carcinogenic mechanism of action. The goals of this study were (1) to identify metabolomic changes induced in the liver by increasing doses of propiconazole in mice, (2) to interpret these results with key previously reported biochemical, transcriptomic, and proteomic findings obtained from mouse liver under the same treatment conditions, and (3) to relate these alterations to those associated with the carcinogenesis process. Propiconazole was administered to male CD-1 mice in the feed for 4 days with six mice per feed level (500, 1250, and 2500 ppm). The 2500 ppm dose level had previously been shown to induce both adenocarcinomas and adenomas in mouse liver after a 2-year continuous feed regimen. Endogenous biochemicals were profiled using liquid chromatography/mass spectrometry and gas chromatography/mass spectrometry methods and 261 were detected. The most populous biochemical class detected was lipids, followed by amino acids and then carbohydrates. Nucleotides, cofactors and vitamins, energy, peptides, and xenobiotics were also represented. Of the biochemicals detected, 159 were significantly altered by at least one dose of propiconazole and many showed strong dose responses. Many alterations in the levels of biochemicals were found in the glycogen metabolism, glycolysis, lipolysis, carnitine, and the tricarboxylic acid cycle pathways Several groups of metabolomic responses were ascribed to the metabolism and clearance of propiconazole: glucuronate, glutathione, and cysteine pathways. Groups of metabolic responses supported previous hypotheses on key events that can lead to propiconazole-induced tumorigenesis: oxidative stress and increases in the cholesterol biosynthesis pathway. Groups of metabolomic responses identified biomarkers associated with neoplasia: increases in glycolysis and increases in the levels of spermidine, sarcosine, and pseudouridine. These results extended the companion transcriptomic and proteomic studies and provided a more complete understanding of propiconazole's effects in mouse liver.

Rural mental health workforce difficulties: a management perspective

INTRODUCTION

The recruitment, retention and training of mental health workers is of major concern in rural Australia, and the Gippsland region of Victoria is no exception. Previous studies have identified a number of common factors in these workforce difficulties, including rurality, difficulties of access to professional development and training, and professional and personal isolation. However, those previous studies have often focused on medicine and been based on the perspectives of practitioners, and have almost ignored the perspectives of managers of rural mental health services. The study reported in this article sought to contribute to the development of a more sustainable and effective regional mental health workforce by complementing earlier insights with those of leading administrators, managers and senior clinicians in the field.

METHODS

The study took a qualitative approach. It conducted semi-structured in-person interviews with 24 managers of health/mental-health services and senior administrators and clinicians working in organisations of varying sizes in the public and private sectors. Thematic content analysis of the transcribed interviews identified core difficulties these managers experienced in the recruitment, retention and training of employees.

RESULTS

The study found that some of the issues commonly resulting in difficulties in recruiting, retaining and developing a trained workforce in rural areas, such as rurality (implying personal and professional isolation, distances to deliver service and small organisations) and a general shortage of trained personnel, are significant in Gippsland. Through its focus on the perspectives of leaders in the management of rural mental health services, however, the study found other key issues that contribute to workforce difficulties. Many, including the unattractive nature of mental health work, the fragmented administration of the mental health system, short-term and tied funding, and shortcomings in training are external to organisations. Interviewees indicated that these issues make it difficult for organisations to support personnel in ways that enhance personal and professional satisfaction and so retention and, in turn, the capacity to recruit new employees. Participants also highlighted issues internal to the organisation. The tensions that flow from the systemic forces require highly creative leadership to negotiate the numerous policy changes, diverse sources of funding, training regimens, worker cohorts and models of care. Managers must nurture the capacity of their own organisation to respond flexibly to the demands, by establishing a responsive culture and structure. They must also encourage the collaboration of their other organisations in their sub-regional grouping and the development of a regional sensibility.

CONCLUSION

The approach taken by the study, particularly its focus on a management perspective, revealed that the difficulties experienced are the product of a core tension between a growing demand for mental health care, emerging specialities and technological advances in the field, and a diminished systemic capacity to support organisations in meeting the demand. Resolving this core tension is a key to the maintenance of a sustainable and effective workforce in Gippsland, and the role of management is crucial to that resolution.

Abstract 1076: Reversible effect of all-trans-retinoic acid on AML12 hepatocyte proliferation and cell cycle progression

The role of all-trans-retinoic acid (atRA) in the regulation of cellular proliferation and differentiation is well documented. Numerous studies have established the cancer preventive properties of atRA which functions to regulate levels of cell cycle proteins essential for the G1/S transition and progression through S phase. Using AML12 cells, a non-transformed immortalized mouse hepatocyte cell line, the goals of this study were to first determine if changes in AML12 cell proliferation could be observed in response to atRA treatment and establish whether this was a suitable system to investigate molecular mechanisms altered by hepatocarcinogens. Cells were treated with 1µM and 5 µM atRA for 2 to 10 days. At various time points, control (DMSO) and treated cells were enumerated to determine the effect of atRA on AML12 cell proliferation. At 5 days of atRA treatment, there was a 56% decrease in the number of atRA treated cells when compared to control cells. This effect was reversible as an increase in cell number was observed two days after removal of atRA from the treatment media. Cell cycle analysis by flow cytometry using propidium iodide stained AML12 cells showed a significant reduction (p<0.05) in S phase cells and a significant increase (p<0.05) in G1 phase cells with 48 hours of atRA treatment when compared to control cells indicating a block at the G1/S checkpoint. Western analysis of control and treated whole cell lysates revealed a decrease in phosphorylated (Serine807/Serine811) retinoblastoma protein (pRb). Taken together, these results indicate that proliferation in AML12 hepatocytes can be reversibly modified by atRA by regulating these cells at the G1/S checkpoint with a reduction in pRb. Previous studies of liver tissues collected from mice exposed to the hepatocarcinogenic fungicide, propiconazole, have revealed an increase in cellular proliferation, increases in atRA metabolism as well as decreases in the levels of hepatic atRA. Based on the results of the present experiments, AML12 hepatocytes provide an optimal in vitro system to elucidate the molecular mechanism by which propiconazole induces hepatotumorigenesis. This work was reviewed by EPA and approved for publication but does not necessarily reflect official Agency policy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1076.

Lack of contribution of covalent benzo[a]pyrene-7,8-quinone-DNA adducts in benzo[a]pyrene-induced mouse lung tumorigenesis

Benzo[a]pyrene (B[a]P) is a potent human and rodent lung carcinogen. This activity has been ascribed in part to the formation of anti-trans-7,8-dihydroxy-7,8-dihydroB[a]P-9,10-epoxide (BPDE)-DNA adducts. Other carcinogenic mechanisms have been proposed: (1) the induction of apurinic sites from radical cation processes, and (2) the metabolic formation of B[a]P-7,8-quinone (BPQ) that can form covalent DNA adducts or reactive oxygen species which can damage DNA. The studies presented here sought to examine the role of stable BPQ-DNA adducts in B[a]P-induced mouse lung tumorigenesis. Male strain A/J mice were injected intraperitoneally once with BPQ or trans-7,8-dihydroxy-7,8-dihydroB[a]P (BP-7,8-diol) at 30, 10, 3, or 0mg/kg. Lungs and livers were harvested after 24h, the DNA extracted and subjected to (32)P-postlabeling analysis. Additional groups of mice were dosed once with BPQ or BP-7,8-diol each at 30 mg/kg and tissues harvested 48 and 72 h later, or with B[a]P (50mg/kg, a tumorigenic dose) and tissues harvested 72 h later. No BPQ or any other DNA adducts were observed in lung or liver tissues 24, 48, or 72 h after the treatment with 30 mg/kg BPQ. BP-7,8-diol gave BPDE-DNA adducts at all time points in both tissues and B[a]P treatment gave BPDE-DNA adducts in the lung. In each case, no BPQ-DNA adducts were detected. Mouse body weights significantly decreased over time after BPQ or BP-7,8-diol treatments suggesting that systemic toxicity was induced by both agents. Model studies with BPQ and N-acetylcysteine suggested that BPQ is rapidly inactivated by sulfhydryl-containing compounds and not available for DNA adduction. We conclude that under these treatment conditions BPQ does not form stable covalent DNA adducts in the lungs or livers of strain A/J mice, suggesting that stable BPQ-covalent adducts are not a part of the complex of mechanisms involved in B[a]P-induced mouse lung tumorigenesis.

Fecal endocrine profiles and ejaculate traits in black-footed cats (Felis nigripes) and sand cats (Felis margarita)

Information regarding the reproductive biology of black-footed cats (BFC) and sand cats (SC) is extremely limited. Our objectives were to: (1) validate fecal hormone analysis (estrogens, E; progestagens, P; androgens, T) for noninvasive monitoring of gonadal activity; (2) characterize estrous cyclicity, ovulatory mechanisms, gestation, and seasonality; and (3) evaluate male reproductive activity via fecal androgen metabolites and ejaculate traits. In both species, the estrous cycle averaged 11-12 days. In BFC (n=8), estrus lasted 2.2+/-0.2 days with peak concentrations of E (2962.8+/-166.3 ng/g feces) increasing 2.7-fold above basal concentrations. In SC (n=6), peak concentrations of E (1669.9+/-83.5 ng/g feces) during estrus (2.9+/-0.2 days) were 4.0-fold higher than basal concentrations. Nonpregnant luteal phases occurred in 26.5% (26 of 98) of BFC estrous cycles, but were not observed in SC (0 of 109 cycles). In both species, P concentrations during pregnancy were elevated (32.3+/-3.0 microg/g feces BFC; 8.5+/-0.7 microg/g feces SC) approximately 10-fold above basal concentrations. Fecal T concentrations in males averaged 3.1+/-0.1 microg/g feces in BFC and 2.3+/-0.0 microg/g feces in SC. Following electroejaculation, 200 to 250 microl of semen was collected containing 29.9 (BFC) to 36.5 (SC)x10(6) spermatozoa with 40.4 (SC) to 46.8 (BFC)% normal morphology. All females exhibited estrous cycles during the study and spermatozoa were recovered from all males on every collection attempt, suggesting poor reproductive success in these species may not be due to physiological infertility.

Global observations of the interstellar interaction from the Interstellar Boundary Explorer (IBEX)

The Sun moves through the local interstellar medium, continuously emitting ionized, supersonic solar wind plasma and carving out a cavity in interstellar space called the heliosphere. The recently launched Interstellar Boundary Explorer (IBEX) spacecraft has completed its first all-sky maps of the interstellar interaction at the edge of the heliosphere by imaging energetic neutral atoms (ENAs) emanating from this region. We found a bright ribbon of ENA emission, unpredicted by prior models or theories, that may be ordered by the local interstellar magnetic field interacting with the heliosphere. This ribbon is superposed on globally distributed flux variations ordered by both the solar wind structure and the direction of motion through the interstellar medium. Our results indicate that the external galactic environment strongly imprints the heliosphere.

Comparison of Interstellar Boundary Explorer observations with 3D global heliospheric models

Simulations of energetic neutral atom (ENA) maps predict flux magnitudes that are, in some cases, similar to those observed by the Interstellar Boundary Explorer (IBEX) spacecraft, but they miss the ribbon. Our model of the heliosphere indicates that the local interstellar medium (LISM) magnetic field (B(LISM)) is transverse to the line of sight (LOS) along the ribbon, suggesting that the ribbon may carry its imprint. The force-per-unit area on the heliopause from field line draping and the LISM ram pressure is comparable with the ribbon pressure if the LOS approximately 30 to 60 astronomical units and B(LISM) approximately 2.5 microgauss. Although various models have advantages in accounting for some of the observations, no model can explain all the dominant features, which probably requires a substantial change in our understanding of the processes that shape our heliosphere.

Global observations of the interstellar interaction from the Interstellar Boundary Explorer (IBEX)

The Sun moves through the local interstellar medium, continuously emitting ionized, supersonic solar wind plasma and carving out a cavity in interstellar space called the heliosphere. The recently launched Interstellar Boundary Explorer (IBEX) spacecraft has completed its first all-sky maps of the interstellar interaction at the edge of the heliosphere by imaging energetic neutral atoms (ENAs) emanating from this region. We found a bright ribbon of ENA emission, unpredicted by prior models or theories, that may be ordered by the local interstellar magnetic field interacting with the heliosphere. This ribbon is superposed on globally distributed flux variations ordered by both the solar wind structure and the direction of motion through the interstellar medium. Our results indicate that the external galactic environment strongly imprints the heliosphere.

Efficacy of lenalidomide oral monotherapy in relapsed or refractory indolent non-Hodgkin's lymphoma: Final results of NHL-001

8560

Background: Lenalidomide has shown activity in a wide range of hematological malignancies. We conducted a phase II trial of single-agent lenalidomide in indolent non-Hodgkin's lymphoma (NHL). Methods: Patients with relapsed or refractory indolent NHL were eligible, with no limit on the number of previous therapies. Oral lenalidomide 25 mg was self-administered once-daily on days 1–21 of every 28-day cycle for up to 52 weeks as tolerated, or until disease progression. The primary endpoint was overall response rate (ORR), with secondary endpoints of response duration, progression-free survival (PFS), and safety. Results: Forty-three patients were enrolled and were evaluable for response and safety. Patients had received a median of 3 prior systemic therapies (1–17) and half of all patients were refractory to their last therapy. The ORR was 23% (10/43), including a complete response (CR) or unconfirmed CR (CRu) rate of 7%. The median time to first response was 3.6 months (1.7–4.2) and the median time to CR or CRu was 4.2 months (1.9–11.1). Twenty-seven percent (6/22) of patients with follicular lymphoma grade 1 or 2, and 22% (4/18) of patients with small lymphocytic lymphoma responded to therapy. The median duration of response has not reached, but is longer than 16.5 months with 7 of 10 responses ongoing at 15–28 months. Median PFS was 4.4 months (2.5–10.4). Adverse events were consistent with the known safety profile of lenalidomide and manageable; the most common grade 3 or 4 adverse events were neutropenia (30% and 16%, respectively) and thrombocytopenia (14% and 5%, respectively). Conclusions: Oral lenalidomide monotherapy produces durable responses with manageable side effects in relapsed or refractory indolent NHL and warrants further investigation in the treatment of indolent NHL.

[Table: see text]