Attaining freshwater and estuarine-water soil saturation in an ecosystem-scale coastal flooding experiment.

Coastal upland forests are facing widespread mortality as sea-level rise accelerates and precipitation and storm regimes change. The loss of coastal forests has significant implications for the coastal carbon cycle; yet, predicting mortality likelihood is difficult due to our limited understanding of disturbance impacts on coastal forests. The manipulative, ecosystem-scale Terrestrial Ecosystem Manipulation to Probe the Effects of Storm Treatments (TEMPEST) experiment addresses the potential for freshwater and estuarine-water disturbance events to alter tree function, species composition, and ecosystem processes in a deciduous coastal forest in MD, USA. The experiment uses a large-unit (2000 m2), un-replicated experimental design, with three 50 m × 40 m plots serving as control, freshwater, and estuarine-water treatments. Transient saturation (5 h) of the entire soil rooting zone (0-30 cm) across a 2000 m2 coastal forest was attained by delivering 300 m3 of water through a spatially distributed irrigation network at a rate just above the soil infiltration rate. Our water delivery approach also elevated the water table (typically ~ 2 m belowground) and achieved extensive, low-level inundation (~ 8 cm standing water). A TEMPEST simulation approximated a 15-cm rainfall event and based on historic records, was of comparable intensity to a 10-year storm for the area. This characterization was supported by showing that Hurricane Ida's (~ 5 cm rainfall) hydrologic impacts were shorter (40% lower duration) and less expansive (80% less coverage) than those generated through experimental manipulation. Future work will apply TEMPEST treatments to evaluate coastal forest resilience to changing hydrologic disturbance regimes and identify conditions that initiate ecosystem state transitions.

Impacts of long-term precipitation manipulation on hydraulic architecture and xylem anatomy of piñon and juniper in Southwest USA.

Hydraulic architecture imposes a fundamental control on water transport, underpinning plant productivity, and survival. The extent to which hydraulic architecture of mature trees acclimates to chronic drought is poorly understood, limiting accuracy in predictions of forest responses to future droughts. We measured seasonal shoot hydraulic performance for multiple years to assess xylem acclimation in mature piñon (Pinus edulis) and juniper (Juniperus monosperma) after 3+ years of precipitation manipulation. Our treatments consisted of water addition (+20% ambient precipitation), partial precipitation-exclusion (-45% ambient precipitation), and exclusion-structure control. Supplemental watering elevated leaf water potential, sapwood-area specific hydraulic conductivity, and leaf-area specific hydraulic conductivity relative to precipitation exclusion. Shifts in allocation of leaf area to sapwood area enhanced differences between irrigated and droughted KL in piñon but not juniper. Piñon and juniper achieved similar KL under ambient conditions, but juniper matched or outperformed piñon in all physiological measurements under both increased and decreased precipitation treatments. Embolism vulnerability and xylem anatomy were unaffected by treatments in either species. Absence of significant acclimation combined with inferior performance for both hydraulic transport and safety suggests piñon has greater risk of local extirpation if aridity increases as predicted in the southwestern USA.

Sustained benefits of continuous subcutaneous insulin infusion.

AIM: To evaluate the efficacy and safety of continuous subcutaneous insulin infusion (CSII), and its impact on glycaemic control, insulin doses and auxological parameters in children with diabetes over a 4-year period. METHOD: A retrospective analysis of all patients treated with CSII. Data on HbA1c, height, weight, insulin doses, hypoglycaemia and diabetic ketoacidosis (DKA) were analysed. RESULTS: 67 patients, aged 1-16 years showed a mean (±SD) HbA1c pre-CSII of 8.2%, decreasing to 7.3% (±0.8%) at 6 months (p<0.01), 7.7% (±0.99) at 2 years (p<0.05), 7.4% (±0.94) at 3 years (n=9, p=0.15) and 7.6% (±0.97) at 4 years (n=4, p=1.0). Insulin doses reduced significantly with a trend towards reduced BMI SDS. Nine preschool children showed HbA1c reduction from 8.4% (±0.94) to 7.4% (±0.32, p<0.01) over 20 months with no episodes of severe hypoglycaemia or DKA. CONCLUSION: The authors demonstrate that CSII is associated with significantly improved sustained glycaemic control, especially in preschool children with diabetes in motivated families.

Allometric relationships predicting foliar biomass and leaf area:sapwood area ratio from tree height in five Costa Rican rain forest species.

We developed allometric equations to predict whole-tree leaf area (A(l)), leaf biomass (M(l)) and leaf area to sapwood area ratio (A(l):A(s)) in five rain forest tree species of Costa Rica: Pentaclethra macroloba (Willd.) Kuntze (Fabaceae/Mim), Carapa guianensis Aubl. (Meliaceae), Vochysia ferru-gi-nea Mart. (Vochysiaceae), Virola koshnii Warb. (Myristicaceae) and Tetragastris panamensis (Engl.) Kuntze (Burseraceae). By destructive analyses (n = 11-14 trees per species), we observed strong nonlinear allometric relationships (r(2) > or = 0.9) for predicting A(l) or M(l) from stem diameters or A(s) measured at breast height. Linear relationships were less accurate. In general, A(l):A(s) at breast height increased linearly with tree height except for Penta-clethra, which showed a negative trend. All species, however, showed increased total A(l) with height. The observation that four of the five species increased in A(l):A(s) with height is consistent with hypotheses about trade--offs between morphological and anatomical adaptations that favor efficient water flow through variation in the amount of leaf area supported by sapwood and those imposed by the need to respond quickly to light gaps in the canopy.

Dietary interventions for multiple sclerosis.

BACKGROUND: Clinical and experimental data suggest that certain dietary regimens, particularly those including polyunsaturated fatty acids (PUFAs) and vitamins might improve outcomes in people with multiple sclerosis (MS). Diets and dietary supplements are much used by people with MS in the belief that they might improve disease outcomes. OBJECTIVES: We performed a Cochrane review of all randomised trials of dietary regimens for MS with the aim of answering MS consumers' questions regarding the efficacy and safety of these interventions. SEARCH STRATEGY: We searched the Cochrane MS Group trial register (February 2006), Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Library, Issue 1, 2006, MEDLINE (PubMed) (1966 to March 2006), EMBASE (1974 to March 2006) and the bibliographies of papers found. SELECTION CRITERIA: All randomised controlled trials comparing a specific dietary intervention, diet plan or dietary supplementation, with no dietary modification or placebo, were eligible. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected articles, assessed trial quality and extracted data. Trial quality was poor, particularly as regards descriptions of randomisation, blinding and adverse event reporting. Some studies had large numbers of drop-outs; dropouts were never included in the analyses. MAIN RESULTS: PUFAs did not have a significant effect on disease progression, measured as worsening of Disability Status Scale. Omega-6 fatty acids (11-23 g/day linoleic acid) had no benefit in 75 relapsing remitting (RR) MS patients (progression at two years: relative risk (RR)=0.78, 95% CI [0.45 to 1.36]) or in 69 chronic progressive (CP) MS patients (RR=1.67, 95% CI [0.75 to 3.72]. Linoleic acid (2.9-3.4 g/day) had no benefit in CPMS (progression at two years: RR=0.78, 95% CI [0.43 to 1.42]). Slight decreases in relapse rate and relapse severity were associated with omega-6 fatty acids in some small studies, however these findings are limited by the limited validity of the endpoints.Omega-3 fatty acids had no benefit on progression at 12 months in 14 RRMS patients or at 24 months in 292 RRMS patients (RR=0.15, 95% CI [0.01 to 3.11], p= 0.22 at 12 months, and 0.82 95% CI [0.65 to 1.03], p=0.08, at 24 months). The low frequency of reported adverse events suggests no major toxicity associated with PUFA administration. No studies on vitamin supplementation and allergen-free diets were analysed as none met the eligibility criteria. AUTHORS' CONCLUSIONS: PUFAs seem to have no major effect on the main clinical outcome in MS (disease progression), and does not substantially affect the risk of clinical relapses over 2 years. However, the data available are insufficient to assess any potential benefit or harm from PUFA supplementation. Evidence bearing on the possible benefits and risks of vitamin supplementation and antioxidant supplements in MS is lacking. More research is required to assess the effectiveness of diets interventions in MS.

Reliance on stored water increases with tree size in three species in the Pacific Northwest.

In tall old forests, limitations to water transport may limit maximum tree height and reduce photosynthesis and carbon sequestration. We evaluated the degree to which tall trees could potentially compensate for hydraulic limitations to water transport by increased use of water stored in xylem. Using sap flux measurements in three tree species of the Pacific Northwest, we showed that reliance on stored water increases with tree size and estimated that use of stored water increases photosynthesis. For Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), water stored in xylem accounted for 20 to 25% of total daily water use in 60-m trees, whereas stored water comprised 7% of daily water use in 15-m trees. For Oregon white oak (Quercus garryana Dougl. ex Hook.), water stored in xylem accounted for 10 to 23% of total daily water use in 25-m trees, whereas stored water comprised 9 to 13% of daily water use in 10-m trees. For ponderosa pine (Pinus ponderosa Dougl. ex Laws.), water stored in xylem accounted for 4 to 20% of total daily water use in 36-m trees, whereas stored water comprised 2 to 4% of daily water use in 12-m trees. In 60-m Douglas-fir trees, we estimated that use of stored water supported 18% more photosynthesis on a daily basis than would occur if no stored water were used, whereas 15-m Douglas-fir trees gained 10% greater daily photosynthesis from use of stored water. We conclude that water storage plays a significant role in the water and carbon economy of tall trees and old forests.

The relationship between tree height and leaf area: sapwood area ratio.

The leaf area to sapwood area ratio (A l:A s) of trees has been hypothesized to decrease as trees become older and taller. Theory suggests that A l:A s must decrease to maintain leaf-specific hydraulic sufficiency as path length, gravity, and tortuosity constrain whole-plant hydraulic conductance. We tested the hypothesis that A l:A s declines with tree height. Whole-tree A l:A s was measured on 15 individuals of Douglas-fir (Pseudotsuga menziesii var. menziesii) ranging in height from 13 to 62 m (aged 20-450 years). A l:A s declined substantially as height increased (P=0.02). Our test of the hypothesis that A l:A s declines with tree height was extended using a combination of original and published data on nine species across a range of maximum heights and climates. Meta-analysis of 13 whole-tree studies revealed a consistent and significant reduction in A l:A s with increasing height (P<0.05). However, two species (Picea abies and Abies balsamea) exhibited an increase in A l:A s with height, although the reason for this is not clear. The slope of the relationship between A l:A s and tree height (ΔA l:A s/Δh) was unrelated to mean annual precipitation. Maximum potential height was positively correlated with ΔA l:A s/Δh. The decrease in A l:A s with increasing tree size that we observed in the majority of species may be a homeostatic mechanism that partially compensates for decreased hydraulic conductance as trees grow in height.

Formation of a functional morphogen gradient by a passive process in tissue from the early Xenopus embryo.

In early development much of the cellular diversity and pattern formation of the embryo is believed to be set up by morphogens. However, for many morphogens, including members of the TGF-beta superfamily, the mechanism(s) by which they reach distant cells is unknown. We have used immunofluorescence to detect, at single cell resolution, a morphogen gradient formed across vertebrate tissue. The TGF-beta ligand is distributed in a gradient visible up to 7 cell diameters (about 150-200 microm) from its source, and is detectable only in the extracellular space. This morphogen gradient is functional, since we demonstrate activation of a high response gene (Xeomes) and a low-response gene (Xbra) at different distances from the TGF-beta source. Expression of the high affinity type II TGF-beta receptor is necessary for detection of the gradient, but the shape of the gradient formed only depends in part on the spatial variation in the amount of receptor. Finally, we demonstrate that the molecular processes that participate in forming this functional morphogen gradient are temperature independent, since the gradient forms to a similar extent whether the cells are maintained at 4 degrees C or 23 degrees C. In contrast, TGF-beta1 internalisation by cells of the Xenopus embryo is a temperature-dependent process. Our results thus suggest that neither vesicular transcytosis nor other active processes contribute to a significant extent to the formation of the morphogen gradient we observe. We conclude that, in the model system used here, a functional morphogen gradient can be formed within a few hours by a mechanism of passive diffusion.

Carbon and nitrogen allocation to male and female reproduction in Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca, Pinaceae).

We measured carbon (respiration, photosynthesis, and production) and nitrogen allocation to male and female cones of Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) to quantify gender-specific: (1) resource allocation to reproduction, and (2) contribution to carbon costs of reproduction via photosynthesis. We also measured foliar photosynthesis and nitrogen concentration ([N]) near and far from female cones to examine the relationship between reproduction and foliar physiology. Over one growing season, male cones required only 8% of all carbon allocated to reproduction, with females consuming the remaining 92%. Female cones, however, had maximum instantaneous refixation rates of 54%, which, integrated over the season, offset 6% of their total carbon requirements, while male cones were completely dependent on vegetative tissues for carbon. Male cones received 22% of all nitrogen allocated to reproduction and female cones received the remaining 78%. Foliage near female cones had elevated photosynthesis during the early stages of cone development and consistently lower [N] than foliage far from cones. Although female cones may photosynthesize, the annual sum of carbon fixed by reproductive structures is minor in comparison to the total carbon allocated to production and respiration.

Activin as a morphogen in Xenopus mesoderm induction.

Activin, a member of the Transforming Growth Factor beta (TGF-beta) superfamily, can behave as a morphogen in cells of the early Xenopus embryo by inducing a range of mesodermal genes in a concentration-dependent manner. This review examines the behaviour of activin as it forms a morphogen gradient. It also discusses how a cell can perceive its position in a concentration gradient in order to activate appropriate mesodermal gene responses.

Barriers to physical activity promotion by general practitioners and practice nurses.

OBJECTIVE: To examine the promotion of physical activity by general practitioners (GPs) and practice nurses (PNs). METHODS: A questionnaire that examined the types of barriers and the levels of their influence as well as stage of change for activity promotion and for personal behaviour was mailed to 846 subjects. RESULTS: The return rate exceeded 70% in each group with a high proportion (69%) of GPs and PNs reporting that they regularly promote physical activity with their patients. GPs were less likely to regularly promote physical activity with their patients if they indicated lack of time as a barrier (odds ratio (OR) = 0.73, 95% confidence interval (CI) 0.58 to 0.93) or lack of incentives (OR = 0.74, 95% CI 0.59 to 0.94), and more likely to promote exercise if they themselves were regular exercisers (OR = 3.19, 95% CI 1.96 to 5.18). However, for PNs longer consultation times (by 1.5 to 2 minutes) had a higher likelihood of producing regular promotion of activity (OR = 1.61, 95% CI 1.02 to 1.62). For PNs personal physical activity stage was the strongest significant predictor of promotion level, but with a stronger effect (OR = 4.77, 95% CI 1.48 to 15.35) than in the GPs. CONCLUSION: The main finding is that GPs in the action or maintenance stage of changing their own physical activity are three times more likely to regularly promote the same behaviour in their patients than those in the other stages; for PNs the same difference quadruples the likelihood of them promoting physical activity. Professional readiness to change is influenced by known system barriers in GPs, and not in PNs, but is more strongly predicted by personal physical activity behaviour in both groups.

Activin has direct long-range signalling activity and can form a concentration gradient by diffusion.

BACKGROUND: Activin has strong mesoderm-inducing properties in the early Xenopus embryo, and has a long-range signalling activity that activates genes in cells distant from a source in a concentration-dependent way. It has not yet been established what mechanism of signal transmission accounts for this and other examples of long-range signalling in vertebrates. Nor is it known whether activin itself acts on distant cells or whether other kinds of molecules are used for long-range signalling. Here we have used a well characterised model system, involving animal caps of Xenopus blastulae treated with activin or transforming growth factor beta, to analyze some fundamental properties of long-range signalling and of the formation of a morphogen gradient. RESULTS: We find that cells distant from the source of activin require functional activin receptors to activate Xbrachyury, a result suggesting that activin itself acts directly on distant cells and that other secondary signalling molecules are not required. We also find that the signals can be transmitted across a tissue that cannot respond to it; this argues against a relay process. We provide direct evidence that labelled activin forms a concentration gradient emanating from its source and extending to the distant cells that express Xbrachyury. Lastly, we show that there is no inherent polarity in the responding tissue that influences either the direction or rate of signalling. CONCLUSIONS: The long-range signalling mechanism by which activin initiates the transcription of genes in a concentration-dependent manner depends on a process of rapid diffusion and the establishment of an activin gradient across the tissue. It cannot be explained by a relay or wave propagation mechanism. Activin itself is the signalling molecule to which distant cells respond.

Factors that influence practice nurses to promote physical activity.

OBJECTIVE: To investigate what factors may influence practice nurses to promote physical activity. METHODS: Postal questionnaires were sent to all practice nurses in the county of Avon, UK in 1994. Specifically, the questionnaire survey explored whether patient, provider, and practice factors influenced practice nurses promotion behaviour. In addition, the stages of change model was used to measure current levels of promoting behaviour. RESULTS: A response rate of 80.9% was achieved. Over 80% of the sample reported currently promoting physical activity to some degree. "Promoting" nurses more frequently followed up all (new, established or targeted) patients' activity progress when compared with "restricted promoting" nurses (P < 0.05). Nurses who engaged in regular exercise were more likely to encourage physical activity as a treatment than "irregularly active" nurses (P < 0.05) for five of six clinical groups with the single exception of people with diabetes. CONCLUSIONS: This study shows that the two stage measures (activity promotion and personal behaviour) of the health care professional are associated with important differences in patient and practice factors for physical activity promotion. Further investigations into the content and quality of delivery are required before planning strategies to develop physical activity in the general practice.

The role of stereotactic biopsy in assessment of nonpalpable breast lesions.

BACKGROUND: When mammography identifies a lesion suspicious for cancer, stereotactic needle core biopsy (SCNB) and needle localization (NL) surgical biopsy are options for obtaining tissue. This study compared the results of these two biopsy methods in evaluating nonpalpable radiologically suspicious breast lesions. METHODS: Records of 292 women who underwent SCNB or surgical biopsy at two institutions were reviewed over 28 months. The women were separated into two groups, under 50 years of age and 50 years of age and older. RESULTS: A total of 70 women over the age of 50 had stereotactic biopsy. One hundred and three had NL biopsies. The rate of positivity was 37% and 33% for stereotactic and NL biopsy respectively (P = 0.693). A total of 44 women under the age of 50 had stereotactic biopsy. Seventy had NL biopsies. The rate of positivity was 7% and 21%, respectively, for stereotactic and NL (P = 0.082). NL surgical biopsy costs on average $2354.00. SCNB averages $949 including follow-up mammogram. CONCLUSION: SCNB is a cost-effective, accurate method of breast biopsy. This report retrospectively compares SCNB with surgical open biopsy aided by NL. The cost savings occurred primarily in surgeon's fees and anesthesia fees. We found no statistical difference in < 50- or > 50-year-old patients in the frequency of the diagnosis of breast cancer when comparing the two types of biopsies.