Author Correction: Crowther et al. reply.

In this Brief Communications Arising Reply, the affiliation for author P. H. Templer was incorrectly listed as 'Department of Ecology & Evolutionary Biology, University of California Irvine, Irvine, California 92697, USA' instead of 'Department of Biology, Boston University, Boston, Massachusetts 02215, USA'. This has been corrected online.

Quantifying global soil carbon losses in response to warming.

The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.

TetR-family transcription factors in Gram-negative bacteria: conservation, variation and implications for efflux-mediated antimicrobial resistance.

BACKGROUND: TetR-family transcriptional regulators (TFTRs) are DNA binding factors that regulate gene expression in bacteria. Well-studied TFTRs, such as AcrR, which regulates efflux pump expression, are usually encoded alongside target operons. Recently, it has emerged that there are many TFTRs which act as global multi-target regulators. Our classical view of TFTRs as simple, single-target regulators therefore needs to be reconsidered. As some TFTRs regulate essential processes (e.g. metabolism) or processes which are important determinants of resistance and virulence (e.g. biofilm formation and efflux gene expression) and as TFTRs are present throughout pathogenic bacteria, they may be good drug discovery targets for tackling antimicrobial resistant infections. However, the prevalence and conservation of individual TFTR genes in Gram-negative species, has to our knowledge, not yet been studied. RESULTS: Here, a wide-scale search for TFTRs in available proteomes of clinically relevant pathogens Salmonella and Escherichia species was performed and these regulators further characterised. The majority of identified TFTRs are involved in efflux regulation in both Escherichia and Salmonella. The percentage variance in TFTR genes of these genera was found to be higher in those regulating genes involved in efflux, bleach survival or biofilm formation than those regulating more constrained processes. Some TFTRs were found to be present in all strains and species of these two genera, whereas others (i.e. TetR) are only present in some strains and some (i.e. RamR) are genera-specific. Two further pathogens on the WHO priority pathogen list (K. pneumoniae and P. aeruginosa) were then searched for the presence of the TFTRs conserved in Escherichia and Salmonella. CONCLUSIONS: Through bioinformatics and literature analyses, we present that TFTRs are a varied and heterogeneous family of proteins required for the regulation of numerous important processes, with consequences to antimicrobial resistance and virulence, and that the roles and responses of these proteins are frequently underestimated.

Soil net nitrogen mineralisation across global grasslands.

Soil nitrogen mineralisation (Nmin), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net Nmin) varies with soil properties and climate. However, because most global-scale assessments of net Nmin are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net Nmin across 30 grasslands worldwide. We find that realised Nmin is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. Potential Nmin only weakly correlates with realised Nmin, but contributes to explain realised net Nmin when combined with soil and climatic variables. We provide novel insights of global realised soil net Nmin and show that potential soil net Nmin data available in the literature could be parameterised with soil and climate data to better predict realised Nmin.

RANK ligand.

RANK ligand (RANKL), a key mediator of bone resorption in normal and pathological states, is expressed as membrane-bound or soluble forms by tissues as diverse as lymph nodes, spleen, thymus and bone-forming cells. In normal bone turnover and in bone metastasis, RANKL stimulates the formation and activity of bone-removing cells, osteoclasts, by binding to its cognate receptor, RANK, on osteoclasts and their progenitors; these processes are disrupted by binding of RANKL to osteoprotegerin (OPG), a soluble decoy receptor. Whilst no mutations in the RANKL gene have yet been identified in human disease, mutations that result in enhanced RANK signalling through inactivation of OPG or activation of RANK are associated with Juvenile Paget's disease and familial expansile osteolysis, respectively. This review focuses on the central role of RANKL in bone resorption and on the therapeutic targeting of RANKL in osteoporosis, humoral hypercalcaemia of malignancy and bone metastasis.

Androgen decreases osteoprotegerin expression in prostate cancer cells.

Osteoprotegerin (OPG), a key regulator of bone resorption, is hypothesized to have a role in prostate cancer (CaP) bone metastasis. As advanced CaP is treated by androgen ablation, we examined if androgen modulates OPG expression by CaP cell lines in vitro. Basal levels of secreted OPG protein were significantly greater in androgen-independent PC-3 cells compared with androgen-responsive LNCaP-FGC cells (P<0.001); OPG was not detected in the androgen-responsive CaP cell lines LAPC-4 or DuCaP. Treatment with 5alpha-dihydrotestosterone (5alpha-DHT) significantly decreased OPG protein levels in both PC-3 and LNCaP-FGC, with maximal suppression using 10(-9)-10(-7) M 5alpha-DHT in PC-3 (P<0.01; day 3), and using 10(-10)-10(-9) M 5alpha-DHT in LNCaP-FGC cells (P<0.01; day 6). OPG messenger RNA levels were not significantly altered by this 5alpha-DHT treatment. Co-treatment with 10(-6) M flutamide blocked 5alpha-DHT inhibition of OPG protein expression in LNCaP-FGC cells. These data suggest that androgen may modulate OPG protein levels in CaP cell lines in vitro using a post-transcriptional mechanism.

A prospective study of adolescents who choose among levonorgestrel implant (Norplant), medroxyprogesterone acetate (Depo-Provera), or the combined oral contraceptive pill as contraception.

OBJECTIVES: Levonorgestrel implants (Norplant) and medroxyprogesterone acetate injections (Depo-Provera) represent additional contraception options for adolescents. The purpose of this study was to examine prospectively clinical profiles among adolescents who chose one of the two long-term contraceptives compared with profiles among those who chose the combined oral contraceptive pill (OCP). METHODS: Girls who needed contraception and did not require confidentiality were presented with a contraceptive menu consisting of Norplant (n = 58), Depo-Provera (n = 66), or OCP (n = 75). At baseline and follow-up visits over 6 months, patients were interviewed regarding gynecologic history, side effect symptoms, and satisfaction. The average age of subjects was 15.5 years (range 11 to 20 years); 66% were African-American and 34% white. RESULTS: Significantly more teens who chose Depo-Provera (73%) reported having used some method of birth control previously than those selecting either Norplant (30%) or OCP (26%). Adolescents who chose either Norplant (34%) or Depo-Provera (43%) were significantly more likely to have been pregnant previously than those choosing OCP (12%). Those selecting Depo-Provera were significantly more likely to report a history of genital infection with Chlamydia trachomatis (42%) than those in the other two contraceptive groups (22%). Prevalences of reported recent depression and fatigue before initiation of treatment were high, exceeding 35% across the three groups. A total of 105 and 40 adolescents were assessed at 3 and 6 months, respectively. At follow-up, more than 80% of OCP users maintained regular menstrual cycles, whereas over 80% of those choosing Norplant or Depo-Provera had disrupted cycles. Complaints of nausea and dizziness among Norplant users and fatigue among Depo-Provera and OCP users increased significantly between the baseline and follow-up visits. Reports of local reactions to the Norplant device were common but not clinically significant. Blood pressure readings, facial acne, and body mass index did not change over time in any treatment group. Subjects in the Norplant and Depo-Provera groups appreciated freedom from daily compliance to maintain contraceptive effectiveness and the "hidden" nature of the method. Appointment compliance at the end of 6 months was 78% for Depo-Provera, 40% for Norplant, and 46% for OCP. CONCLUSIONS: The implant and injection forms of contraception appear to be especially popular among girls with previous pregnancies or birth control use. The common occurrences of medical symptoms and sexually transmitted diseases before initiation of therapy underscore the importance of baseline evaluation. Norplant users may be warned about nausea and dizziness as well as minor local symptoms around the insertion site and unpredictable uterine bleeding patterns. Adolescent patients choosing Depo-Provera may expect amenorrhea by the end of 6 months of therapy along with possible fatigue. Early intervention may be needed with adolescents who choose Norplant or OCP to encourage better compliance with follow-up appointments.

The application of atomic force microscopy for the detection of microcrystals in synovial fluid from patients with recurrent synovitis.

Synovial fluid from 33 patients with inflammatory arthritis was examined with a polarized light microscope (PLM) and an atomic force microscope (AFM). Two samples were imaged with a transmission electron microscope (TEM) to determine calcium/phosphate ratios and identify microcrystals of calcium pyrophosphate dihydrate and octacalcium phosphate. Additional correlative x-ray diffraction studies were performed on several samples including purified hydroxyapatite and sodium chloride crystals. Monosodium urate, calcium pyrophosphate dihydrate, hydroxyapatite, octacalcium phosphate, and cholesterol crystals were identified with AFM. AFM images of these microcrystals revealed detailed surface topology, including lattice parameters and structural irregularities at the crystals' surface. These features were consistent with those obtained by TEM and x-ray diffraction studies. In addition, AFM images revealed that some specimens contained microcrystals that were undetected by PLM and/or TEM. These results suggest that AFM may provide a simple yet powerful technique for the detection of microcrystals in synovial fluid taken from patients with crystal-induced arthritis.

The natural history of asymptomatic thoracic disc herniations.

STUDY DESIGN: Magnetic resonance imaging was used to determine the natural history of asymptomatic thoracic disc herniations. OBJECTIVES: To determine whether thoracic disc herniations change in size over time. SUMMARY OF BACKGROUND DATA: Based on previous work by the authors of the present study, the incidence of asymptomatic thoracic disc herniations is approximately 37%. The natural history of thoracic disc herniations is unknown. The natural history of lumbar and cervical disc herniations in symptomatic individuals who become asymptomatic has been shown in multiple studies frequently to result in a decrease in size of the herniation. METHODS: Twenty patients with 48 asymptomatic thoracic herniations previously diagnosed with magnetic resonance imaging underwent repeat magnetic resonance imaging using sagittal T1-weighted spine echo and axial multiplanar gradient refocused images at each thoracic disc level from T1 to T12 for a mean follow-up period of 26 months. Midsagittal canal diameter was recorded, and disc herniation square area was measured using a computer-assisted digitizing program. Disc herniations were categorized according to percentage of canal compromise. The change in size of the disc herniations over time was analyzed. RESULTS: All patients remained asymptomatic during the follow-up period. A total of 48 disc herniations were identified from the original magnetic resonance images. There were 21 small (0-10% canal compromise) disc herniations, 20 medium (> 10-20%) disc herniations, and seven large (> 20%) disc herniations. Of the 21 small disc herniations, 18 showed no significant change in size, whereas three showed a measurable increase in size. Of the 20 medium-sized disc herniations, 16 showed either a small or no change in size, one showed a significant increase in size, and three showed a significant decrease in size. Of the seven large disc herniations, three demonstrated no change in size, and four demonstrated a significant decrease in size. In addition, five new disc herniations were detected in four patients; one was small, and four were moderate in size. CONCLUSIONS: Based on the results of this study, the authors believe that asymptomatic disc herniations may well exist in a state of relative flux, yet exhibit little change in size and remain asymptomatic. There was a trend, however, for small disc herniations either to remain unchanged or increase in size and for large disc herniations often to decrease in size.

Setting a research agenda to promote nursing research.

This study is a first step in the process of focusing research efforts in a developing nursing research program. A two-round Delphi technique, a method for formulating consensus, was employed to address the aim of organizationally reaching consensus regarding nursing research priorities. Questionnaires were mailed to "experts," defined as all registered nurses within the division (N = 634). Round 1 respondents identified 609 different research items, which were then sorted and categorized into a 100-item Round 2 questionnaire. Research directives and program planning will center around the priority areas.

A descriptive study of the CE needs of nurses serving adolescents in the community.

The purpose of this descriptive study was to develop a two-pronged community education database to improve the quality of response to professionals' self-assessed educational needs. The database was designed to include both the self-assessed level of the respondents' learning needs and their perception of the importance of mastery of specific content in reaching targeted outcomes for the adolescents they serve. Sixty-one percent of the 425 surveys mailed to professionals from central and southeastern Ohio were analyzed. Responses were weighted and a scattergraph of the mean scores for each topic was plotted. Implications for nursing continuing education (CE) are discussed.

Over-expression of p53 mutants in LNCaP cells alters tumor growth and angiogenesis in vivo.

This study has investigated the impact of three specific dominant-negative p53 mutants (F134L, M237L, and R273H) on tumorigenesis by LNCaP prostate cancer cells. Mutant p53 proteins were associated with an increased subcutaneous "take rate" in NOD-SCID mice, and increased production of PSA. Tumors expressing F134L and R273H grew slower than controls, and were associated with decreased necrosis and apoptosis, but not hypoxia. Interestingly, hypoxia levels were increased in tumors expressing M237L. There was less proliferation in F134L-bearing tumors compared to control, but this was not statistically significant. Angiogenesis was decreased in tumors expressing F134L and R273H compared with M237L, or controls. Conditioned medium from F134L tumors inhibited growth of normal human umbilical-vein endothelial cells but not telomerase-immortalized bone marrow endothelial cells. F134L tumor supernatants showed lower levels of VEGF and endostatin compared with supernatants from tumors expressing other mutants. Our results support the possibility that decreased angiogenesis might account for reduced growth rate of tumor cells expressing the F134L p53 mutation.

Patient controlled analgesia for labour: a comparison of remifentanil with pethidine.

We compared the analgesic efficacy and safety of remifentanil and pethidine via patient controlled analgesia for women in established uncomplicated labour. Women received either remifentanil 40 microg with a 2-min lockout (n = 20) or pethidine 15 mg with a 10-min lockout (n = 19). Visual analogue scores for pain during the study and for overall pain were similar for both groups (mean (SD) 6.4 (1.5) cm for remifentanil and 6.9 (1.7) cm for pethidine). The area under the curve for visual analogue scores of satisfaction with analgesia was higher for remifentanil than for pethidine (p = 0.001). Maternal arterial oxygen saturation was similar in both groups. Neurologic and Adaptive Capacity Scores at 30 min were higher for remifentanil than for pethidine (median (interquartile range [range]) 36 (34.5-37 [32-39]) vs 34 (33-35 [30-35]), respectively; p = 0.003).

Surgical anatomy of the superficial peroneal nerve in the ankle and foot.

The subcutaneous (sensory) portion of the superficial peroneal nerve was dissected in 25 cadaver lower limbs under loupe magnification. Three distinct branching pattern types were noted. Type A (72%) consisted of a pattern where the nerve penetrated the crural fascia to become subcutaneous at an average distance of 12.3 cm proximal to the ankle joint, then divided at a mean distance of 4.4 cm proximal to the ankle into two major branches: a large medial dorsal cutaneous nerve and a smaller more laterally located intermediate dorsal cutaneous nerve. Type B (16%) consisted of a pattern where both the medial and intermediate dorsal cutaneous nerve arose independently from the superficial peroneal nerve, with the medial dorsal cutaneous nerve having a similar course to that found in Type A, while the intermediate dorsal cutaneous nerve penetrated the crural fascia posterior to the fibula 5.5 cm proximal to the ankle joint and coursed medially to cross the lateral aspect of the fibula at mean distance 4.5 cm above the ankle joint. Type C (12%) consisted of a pattern where the medial dorsal cutaneous nerve and the intermediate dorsal cutaneous nerve arose independently and the medial dorsal cutaneous nerve coursed similar to that in Type A; however, the intermediate dorsal cutaneous nerve penetrated the crural fascia anterior to the fibula an average of 4.9 cm above the ankle joint and continued in close proximity to the anterior fibular border. In all patterns the mean diameters of the medial dorsal cutaneous nerve and intermediate dorsal cutaneous nerve at the ankle were 2.9 mm and 2 mm, respectively. At the level of the malleoli, the medial dorsal cutaneous nerve was located approximately one half the distance from the lateral malleolus to medial malleolus while the intermediate dorsal cutaneous nerve was approximately one third the distance. Appreciation of these branch patterns and the quantified relationships should assist nerve protection during surgical procedures as well as aid rapid nerve isolation for exploration or decompression. Branches especially at risk for iatrogenic injury include: (1) the intermediate dorsal cutaneous nerve of Type B where the nerve crosses the lateral surface of the distal fibula; (2) the intermediate dorsal cutaneous nerve of Type C where the nerve travels adjacent to the anterior border of the fibula; and (3) the intermediate dorsal cutaneous nerve and the medial dorsal cutaneous nerve at the level of the ankle, where they are at risk during anterior ankle arthrotomy or arthroscopy.

Does resource availability, resource heterogeneity or species turnover mediate changes in plant species richness in grazed grasslands?

Grazing by large ungulates often increases plant species richness in grasslands of moderate to high productivity. In a mesic North American grassland with and without the presence of bison ( Bos bison), a native ungulate grazer, three non-exclusive hypotheses for increased plant species richness in grazed grasslands were evaluated: (1) bison grazing enhances levels of resource (light and N) availability, enabling species that depend on higher resource availability to co-occur; (2) spatial heterogeneity in resource availability is enhanced by bison, enabling coexistence of a greater number of plant species; (3) increased species turnover (i.e. increased species colonization and establishment) in grazed grassland is associated with enhanced plant species richness. We measured availability and spatial heterogeneity in light, water and N, and calculated species turnover from long-term data in grazed and ungrazed sites in a North American tallgrass prairie. Both regression and path analyses were performed to evaluate the potential of the three hypothesized mechanisms to explain observed patterns of plant species richness under field conditions. Experimental grazing by bison increased plant species richness by 25% over an 8-year period. Neither heterogeneity nor absolute levels of soil water or available N were related to patterns of species richness in grazed and ungrazed sites. However, high spatial heterogeneity in light and higher rates of species turnover were both strongly related to increases in plant species richness in grazed areas. This suggests that creation of a mosaic of patches with high and low biomass (the primary determinant of light availability in mesic grasslands) and promotion of a dynamic species pool are the most important mechanisms by which grazers affect species richness in high productivity grasslands.

Patient-controlled analgesia for labour using remifentanil: a feasibility study.

We have investigated the efficacy and safety of remifentanil in a patient-controlled analgesia device for labour in 21 women. Remifentanil was available in increasing doses (bolus doses 0.25-1.0 microg x kg(-1)) with and without a background infusion (0.025-0.05 microg x kg(-1) x min(-1)). A lockout time of 2 min was used. Thirteen out of 21 (62%) women chose to continue using remifentanil up to and during delivery. Nineteen out of 21 (90%) achieved a reduction in pain score from baseline. Using a VAS of 0-10 cm the median maximum reduction in pain score was 3 cm (range 0-8 cm). There was a significant reduction (P<0.05) from baseline pain scores (median= 8 cm) to scores at bolus doses in the range 0.25-0.5 microg x kg(-1) (median=5 cm). There were no significant reductions in the fetal heart rate. Apgar scores and cord blood gas analyses remained within normal limits. We conclude that a remifentanil patient-controlled analgesia system (bolus doses 0.25-0.5 microg x kg(-1), without a background infusion) may safely provide worthwhile, although incomplete, analgesia for labour.

Assessment of tracheal intubation in children after induction with propofol and different doses of remifentanil.

Tracheal intubating conditions were assessed in 112 children after induction of anaesthesia with propofol and remifentanil 1.0, 2.0 or 3.0 micro g.kg-1. Subjects in a control group were given propofol and mivacurium 0.2 mg.kg-1. Haemodynamic and respiratory parameters were recorded. Plasma catecholamine levels were measured in a subgroup of 40 children. Intubating conditions were acceptable in 14/28 (50%), 18/26 (69%) and 22/27 (82%) in those subjects given remifentanil 1.0, 2.0 or 3.0 micro g.kg-1, respectively, and in 27/28 (96%) of the control group. Intubating conditions in subjects given remifentanil 3.0 micro g.kg-1 were better than in those given remifentanil 1.0 micro g.kg-1 (p < 0.05). There were no significant differences in intubating conditions between those given remifentanil 3.0 micro g.kg-1 and the control group. Systolic blood pressure and heart rate increased in response to tracheal intubation in subjects given remifentanil 1.0 micro g.kg-1 and in the control group (p < 0.05). Time to resumption of spontaneous respiration was prolonged in subjects given remifentanil 3.0 micro g.kg-1 (p < 0.001). In conclusion, remifentanil 2 micro g.kg-1 provides acceptable intubating conditions and haemodynamic stability without prolonging the return of spontaneous respiration.