bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards a population ecology of stressed environments: the effects of zinc on the springtailFolsomia candida
Authors: NOËL HELEN L. , HOPKIN STEVE P. , HUTCHINSON THOMAS H. , WILLIAMS TIM D. , SIBLY RICHARD M. 
Published: March 2006

SummaryTo understand population dynamics in stressed environments it is necessary to join together two classical lines of research. Population responses to environmental stress have been studied at low density in life table response experiments. These show how the population's growth rate (pgr) at low density varies in relation to levels of stress. Population responses to density, on the other hand, are based on examination of the relationship betweenpgrand population density.The joint effects of stress and density onpgrcan be pictured as a contour map in whichpgrvaries with stress and density in the same way that the height of land above sea level varies with latitude and longitude. Here a microcosm experiment is reported that compared the joint effects of zinc and population density on thepgrof the springtailFolsomia candida(Collembola).Our experiments allowed the plotting of a complete map of the effects of density and a stressor onpgr. Particularly important was the position of thepgr= 0 contour, which suggested that carrying capacity varied little with zinc concentration until toxic levels were reached.This prediction accords well with observations of population abundance in the field. The method also allowed us to demonstrate, simultaneously, hormesis, toxicity, an Allee effect and density dependence.The mechanisms responsible for these phenomena are discussed. As zinc is an essential trace element the initial increase inpgris probably a consequence of dietary zinc deficiency. The Allee effect may be attributed to productivity of the environment increasing with density at low density. Density dependence is a result of food limitation.Synthesis and applications.We illustrate a novel solution based on mapping a population's growth rate in relation to stress and population density. Our method allows us to demonstrate, simultaneously, hormesis, toxicity, an Allee effect and density dependence in an important ecological indicator species. We hope that the approach followed here will prove to have general applicability enabling predictions of field abundance to be made from estimates of the joint effects of the stressors and density on population growth rate.
Point transect sampling with traps or lures
Authors: BUCKLAND STEPHEN T. , SUMMERS RON W. , BORCHERS DAVID L. , THOMAS LEN 
Published: March 2006

SummaryThe ability to monitor abundance of animal populations is becoming increasingly important, in light of growing concerns over the loss of biodiversity through anthropogenic changes. A widely used tool for such monitoring is distance sampling, in which distances of detected animals from a line or point are modelled, to estimate detectability and hence abundance. Nevertheless, many species still prove problematic to survey. We have developed two extensions to point transect sampling that potentially allow abundance to be estimated for a number of species from diverse taxa for which good survey methods have not previously been available.For each method, the primary survey comprises a random sample of points, or more usually a systematic grid of points, through the region of interest. Animals are lured to a point, or trapped at a point, and the number of animals observed at each point is recorded. A separate study is conducted on a subset of animals, to record whether they respond to the lure or enter the trap, for a range of known distances from the point. These data are used to estimate the probability that an animal will respond to the lure or enter the trap, as a function of its initial distance from the point. This allows the counts to be converted to an estimate of abundance in the survey region.We illustrated the methods using a lure survey of crossbillsLoxiaspp. in coniferous woodland in Scotland.Synthesis and applications.Two extensions of point transect sampling that use the same statistical methodology, lure point transects and trapping point transects, have been developed. Lure point transects extend the applicability of distance sampling to species that can be lured to a point, while trapping point transects potentially allow abundance estimation of species that can be trapped, with fewer resources needed than trapping webs and conventional mark–recapture methods.
Light and thermal environments as modified by a wheat crop: effects on weed seed germination
Authors: KRUK BETINA , INSAUSTI PEDRO , RAZUL ANDREA , BENECH‐ARNOLD ROBERTO 
Published: March 2006

Summary

Knowledge of the regulatory effects of the crop canopy on weed seed germination is necessary to understand fully the behaviour of weed seed banks during a crop cycle. It is well known that canopy presence interferes with seed germination through modifications to the light and thermal environment, but the changing effect of a growing canopy has not been assessed, thus precluding the identification of shading‐intensity thresholds for triggering the different types of canopy‐detection mechanisms in different seed populations.
Field experiments were performed with artificially modified thermal and light environments, using two types of seed banks (seeds buried or located at the soil surface). Conditions below a wheat canopy were modified to match light and thermal conditions prevailing on bare soil (i.e. soil without vegetation).
Most weed emergence patterns during the early stages of crop establishment were not modified by the thermal regime produced by the incipient canopy compared with a bare soil control. However, the reduction of the red : far‐red ratio from the bare soil value of 1·2–0·9 below the wheat canopy reduced germination of some weed species located at the soil surface, and the effect could by reversed by far‐red filters.
The weed Galinsoga parviflora developed two generations during the crop cycle. The modified light and thermal environments beneath an establishing wheat canopy was not sufficient to inhibit the germination of Galinsoga parviflora, even if seeds were located at the soil surface. Only for seeds of the second generation, dispersed from seeds of the first plant generation, was there sufficient modification of the photothermal environment below the wheat canopy to interfere with dormancy termination.
Synthesis and applications. Understanding seed responses to modifications in the photothermal environment below a crop canopy (e.g. wheat crop) should allow us to improve weed management strategies by manipulating crop canopy attributes. This could be achieved by modification of sowing date, crop density, spatial arrangement and genotype. For example, increasing the crop plant density would diminish the number of weeds emerging during the first phase of crop establishment. This strategy would be appropriate where weed seeds are predominantly located at the soil surface, typically found in a no‐till cropping system.
Long‐term demographic fluctuations in an orchid species driven by weather: implications for conservation planning
Authors: PFEIFER MARION , WIEGAND KERSTIN , HEINRICH WOLFGANG , JETSCHKE GOTTFRIED 
Published: March 2006

Summary

Management decisions are increasingly based on matrix models intended to predict the long‐term fate of endangered species. However, certain elements of these models, such as life‐state transition probabilities (vital rates), are difficult to parameterize and their values may vary depending on external conditions such as weather. Details of how weather might influence population performance are rare, yet necessary to assess the effects of global climate change on a species’ distribution.
Based on a 26‐year data set of a population of Himantoglossum hircinum in a nature reserve in Germany, variations of life‐history traits and vital rates were studied. Matrix analysis was used to identify the most important life‐state transitions for population growth. Multiple linear regression was used to quantify the response of population traits and vital rates to changing weather conditions.
Population size increased exponentially and density effects could not be observed. Flowering plants and large plants had the highest and second highest reproductive value, respectively. The population's finite rate of increase fluctuated strongly among years; life‐history traits varied strongly and were interlinked, thereby violating the assumptions of matrix modelling in a population viability analysis.
Some vital rates and the population growth rate showed a trend over the total period. A certain and sometimes large amount of that variability could be attributed to variability of weather conditions, with warmer winter conditions favouring population performance. Prediction of population size was fairly accurate within a time frame of 10 years, but size class structure was not.
Synthesis and applications. Matrix modelling proved to be unreliable for predicting long‐term population dynamics, despite the long‐term data set used for matrix construction. This can be explained by weather‐dependent variability of vital rates driving population dynamics. A minimum study period of 4 years is necessary to produce relevant information for model development. Our study emphasizes the need for critical evaluation of management decisions based only on single short‐term studies and for studies covering longer time intervals than 2–3 years.
Influence of glutamine on pancreatic blood flow and apoptosis of pancreatic acinar in rats with severe acute pancreatitis
Authors: XU Xue Feng , LOU Wen Hui , WANG Dan Song , JIN Da Yong , NI Xiao Lin , WU Zhao Han 
Published: March 2006

OBJECTIVE:  To investigate the role of glutamine on splanchnic blood flow, apoptosis of pancreatic acinar and the underlying mechanism in rats with severe acute pancreatitis.METHODS:  Forty‐eight rats were randomized into two groups: the glutamine group (n = 24) and the severe acute pancreatitis group (n = 24). Jejunotomy was performed in all rats: the glutamine group also received glutamine, and the severe acute pancreatitis group received normal saline. Each group was then subdivided into three subgroups of eight rats each, with the rats be killed at 12, 24 and 36 h after the operation, respectively. A control group underwent sham operation (n = 8). The regional pancreatic microvascular blood flow was measured by Doppler ultrasound. The blood flow of the portal vein, splenic artery and superior mesenteric artery were also recorded. Apoptosis of pancreatic acinar cells was evaluated by TUNEL method.RESULTS:  The regional pancreatic microvascular blood flow (KHz) decreased significantly in the severe acute pancreatitis group (P < 0.01), and continued to decrease after 24 h (vs. 12 h, P < 0.01). The blood flow of the portal vein, splenic artery and superior mesenteric artery also decreased in the severe acute pancreatitis group. The glutamine group showed increased regional pancreatic microvascular blood flows, as well as increased blood flow of the portal vein, splenic artery and superior mesenteric artery (vs. the severe acute pancreatitis group, P < 0.01). The apoptotic index of pancreatic acinar in the glutamine group was higher than in the severe acute pancreatitis group (P < 0.01), and both were much higher than that in the control group (P < 0.01).CONCLUSIONS:  Enteral administration of glutamine increased the splanchnic blood flow in severe acute pancreatitis rats. The apoptotic index of pancreatic acinar was negatively correlated with the severity of the disease. The interrelation between glutamine and apoptosis in severe acute pancreatitis is worthy of further investigation.
Treatment of surgically induced acute liver failure by transplantation of HNF4‐overexpressing embryonic stem cells
Authors: KUAI Xiao Ling , CONG Xiao Qian , DU Zhong Wei , BIAN Yu Hai , XIAO Shu Dong 
Published: March 2006

OBJECTIVE:  Tissue‐specific stem cells from differentiating embryonic stem (ES) cells are both pluripotent and genetically flexible. Recent observations indicate that ES cells can differentiate into hepatocytes. Therefore, cell‐based therapy can potentially be a therapeutic alternative to liver transplantation. In this study the treatment of acute liver failure in rats by transplantation of hepatocyte nuclear factor 4 (HNF4)‐overexpressing ES cells was investigated.METHODS:  The HNF4 was transfected into ES cells and ES cell clones overexpressing HNF4 were selected. The levels of markers of hepatocyte differentiation, including albumin, transthyretin, glucose‐6‐phosphates (G‐6‐P) and SAPK/ERK kinase‐1 (SEK1) mRNA, were tested in spontaneously differentiated HNF4‐overexpressing ES cells by reverse transcription‐polymerase chain reaction (RT‐PCR). The ultrastructure of the spontaneously differentiated HNF4‐overexpressing ES cells was examined by electron microscopy. To induce acute liver failure, Sprague–Dawley rats were subjected to 90% hepatectomy and given 5% oral dextrose. The rats were divided into three groups. The rats in the treatment group (n = 12) received intraliver injection of 2 × 107 undifferentiated HNF4‐overexpressing ES cells from the same clone, the rats in control group 1 (n = 12) received 2 × 107 undifferentiated ES cells, and the rats in control group 2 (n = 12) received the same volume of media without any cells.RESULTS:  All rats in control group 1 and control group 2 died within 72 h, while 33% of rats that received undifferentiated HNF4‐overexpressing ES cells transplantation survived more than 1 month. Spontaneously differentiated HNF4‐overexpressing ES cells only expressed transthyretin mRNA. The cells were rich in mitochondrion and catalase‐containing peroxisomes in ultrastructure.CONCLUSIONS:  Transplantation of ES cells could be a potential treatment in supporting life during acute liver insufficiency and could be a bridge to orthotopic liver transplantation.
Abdominal pain related to mitochondrial neurogastrointestinal encephalomyopathy syndrome may benefit from splanchnic nerve blockade
Authors: ÇELEBI NALAN , ŞAHIN ALTAN , CANBAY ÖZGÜR , ÜZÜMCÜGIL FILIZ , AYPAR ULKÜ 
Published: March 2006

SummaryPatients diagnosed with abdominal pain related to mitochondrial neurogastrointestinal encephalopathy (MNGIE) may benefit from splanchnic nerve blockade. MNGIE, varying in age of onset and rate of progression, is caused by loss of function mutation in thymidine phosphorylase gene. Gastrointestinal dysmotility, pseudo‐obstruction and demyelinating sensorimotor peripheral neuropathy (stocking‐glove sensory loss, absent tendon reflexes, distal limb weakness, and wasting) are the most prominent manifestations. Patients usually die in early adulthood (mean 37.6 years; range 26–58 years). We report a case of an 18‐year‐old patient with MNGIE. Our patient's abdominal pain was relieved after splanchnic nerve blockade.
How many freshwater diatoms are pH specialists? A response to Pither & Aarssen (2005)
Authors: Telford Richard J. , Vandvik Vigdis , Birks H. J. B. 
Published: March 2006

Abstract Pither & Aarssen (2005) propose a null model approach to assess the proportion of niche specialist taxa along ecological gradients. They apply this methodology to a large data set of lacustrine diatom assemblages and conclude that a majority of the taxa are generalists on a pH gradient. This conflicts with previous work, which shows that many diatom taxa have a statistically significant relationship with pH. We demonstrate the methods used by Pither & Aarssen (2005) have a high Type II error for rare taxa, and that this problem is compounded by the non‐uniform sampling of the pH gradient which effectively precludes acid‐lake specialist diatoms from being recognized as such. We re‐analyse the data used by Pither & Aarssen (2005) and show that most of the diatoms have a statistically significant relationship with pH, and we thus refute their conclusions that few diatom species are specialists.
What's new: innovative concepts in inflammatory bowel disease
Authors: Sandborn W. J. 
Published: March 2006

AbstractInflammatory bowel disease (IBD) has been the subject of recent intense research and development. A greater insight into the basic pathological mechanisms of ulcerative colitis (UC) and Crohn's disease (CD) has resulted in the emergence of more sophisticated and effective management options. Additionally, established therapies are attracting renewed interest with novel dosage regimens and new formulations offering improved efficacy whilst maintaining an excellent tolerance profile.High dose 5‐aminosalicylic acid (5‐ASA) has been a focus for investigation in recent clinical trials. The ASCEND study, which compared a 4.8 g/day dose with a 2.4 g/day dose, demonstrated that high dose mesalazine was significantly superior in achieving treatment success and symptom control, whilst maintaining a comparable tolerance and safety profile. The development of biotechnology agents targeted against tumour necrosis factor (TNF) provides promise of new treatment options in both CD and UC. The efficacy of CDP571, adalimumab and certolizumab have been investigated in CD, and infliximab, which is currently approved as an agent in inflammatory and fistulizing CD, has also been recently investigated in UC. Investigational pipeline molecules such as natalizumab, MLN‐02, an anti‐interleukin 12 antibody and sargramostim, have also shown encouraging results from early studies and are now undergoing evaluation in large clinical trials.
Inflammatory bowel disease: the view of the surgeon
Authors: Hancock L. , Windsor A. C. , Mortensen N. J. 
Published: March 2006

AbstractDespite advances in medical therapy, surgery is required in approximately 30–40% of patients with ulcerative colitis (UC) and 70–80% of patients with Crohn's disease (CD) at some point during their lifetime. For patients with UC, surgery may be curative, whereas recurrence of CD following surgery is common due to the potentially pan‐enteric distribution of the disease. As a result, the indications and surgical management of the disease may be quite different. For UC, the surgeon is involved in the identification of new cases, management of severe disease, recognition of dysplasia and restorative proctocolectomy. Most of the advances in surgery for UC have been in novel techniques relating to the ileal pouch–anal anastomosis, which can now be performed safely for UC with a 10% pouch failure rate long term. For CD, the surgeon is involved in the management of small bowel and ileo‐colonic disease, Crohn's colitis and perianal disease. Advances in the surgical management of CD include strictureplasty for extensive small bowel disease, laparoscopic ileo‐caecal resection and a combined medical and surgical approach to perianal disease. For both CD and UC close liaison between the gastroenterologist and colorectal surgeon is essential.
New lessons: classic treatments, expanding options in ulcerative colitis
Authors: Hanauer S. B. 
Published: March 2006

AbstractUlcerative colitis (UC) of moderate severity is a common presentation in gastroenterological practice and a number of treatment options exist to rapidly and effectively induce remission. This review highlights how novel formulations and dosing regimens can ensure treatment success at a greater convenience for the patient with no increased risk of adverse effects. 5‐aminosalicyclic acid (5‐ASA) is well tolerated with a low incidence of adverse effects, and has a significant role in the management of UC. Different formulations of oral 5‐ASA are now available and allow targeted treatment to inflammatory areas of the small bowel and ascending colon. 5‐ASA is often initiated at a low dose for patients with mild to moderately active UC and with increasing doses for those who fail or have a poor response. 5‐ASA at high doses is increasingly being used as induction therapy for active UC, particularly in patients with recurrent and/or extensive disease. The recent ASCEND studies show that an induction dose of 5‐ASA of 4.8 g daily in patients with moderate UC is significantly more effective and resolves symptoms faster compared with a daily dose of 2.4 g. The evidence provided by the ASCEND studies support the rationale for a ‘top‐down’ dosing strategy for UC where more potent therapies are introduced at an earlier stage of moderately severe disease.
New thinking: theory vs practice. A case study illustrating evidence‐based therapeutic decision making
Authors: Travis S. P. L. 
Published: March 2006

AbstractEvidence‐based medicine (EBM) plays a key role for decision making in clinical practice. Clinicians are encouraged to adhere to treatment guidelines based on high quality clinical trials, systematic reviews and meta‐analyses, that are the focus of the Cochrane Collaboration. EBM is not, however, a panacea for medical decision making. The results of randomized clinical trials apply to populations of patients, and the challenge is to translate the results to individuals. Individual patients require different thought processes because presentation and response vary, and external factors (e.g. patient preference) influence the choice of treatment. The application of EBM demands clinical judgement. The case of a 28 year old scientist who presented with typical features of moderate ulcerative colitis, illustrates the dilemma. At each stage of his illness the treatment options based on EBM were discussed, including high dose 5‐aminosalicyclic acid with or without topical therapy, corticosteroids, infliximab, immunomodulation, complementary therapy and surgery. Ultimately, therapeutic decisions depended on the patient's circumstances, preferences and response. Decisions should avoid circular motion caused by the illusion of progress and always consider the direction of travel.
Degradation in insulin sensitivity with increasing severity of the metabolic syndrome in obese postmenopausal women
Authors: Karelis A. D. , Henry J.‐F. , St‐Pierre D. H. , Prud'homme D. , Rabasa‐Lhoret R. 
Published: March 2006

Aim:  We investigated the relationship between insulin sensitivity and the graded increase in the number of features of the metabolic syndrome in a cross‐sectional sample of obese postmenopausal women. We hypothesized that insulin sensitivity would deteriorate with an increased number of metabolic syndrome phenotypes.Methods:  Insulin sensitivity was measured in 75 obese postmenopausal women (age: 57.3 ± 5.3 years; BMI: 32.8 ± 4.5 kg/m2) by using both the hyperinsulinaemic–euglycaemic clamp and the homeostasis model assessment (HOMA‐IR). Features of the metabolic syndrome included visceral fat (>130 cm2), HDL‐cholesterol (<1.29 mmol/l), fasting triglycerides (≥1.7 mmol/l), blood pressure (≥130/≥85 mmHg) and fasting glucose (≥6.1 mmol/l). Participants were classified into three categories based on the presence of metabolic syndrome phenotypes: 0–1 vs. 2 vs. ≥3 features of the metabolic syndrome.Results:  We found that insulin sensitivity decreased in a graded fashion (12.19 ± 3.2 vs. 11.80 ± 2.3 vs. 9.29 ± 2.6 mg/min/FFM) and HOMA‐IR increased in a similar manner (2.95 ± 1.1 vs. 3.28 ± 1.3 vs. 4.65 ± 2.2), as the number of features of the metabolic syndrome increased from 0–1 to ≥3. When insulin sensitivity was statistically adjusted for visceral fat (as measured by computed tomography) and plasma triglycerides, the differences among groups were abolished.Conclusions:  These findings suggest that a decreased insulin sensitivity is associated with increased features of the metabolic syndrome in obese postmenopausal women and that visceral fat as well as plasma triglyceride accumulation might be potential mediators of this relationship.