bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporally structured replay of neural activity in a model of entorhinal cortex, hippocampus and postsubiculum
Authors: Hasselmo Michael E. 
Published: October 2008

AbstractThe spiking activity of hippocampal neurons during rapid eye movement (REM) sleep exhibits temporally structured replay of spiking occurring during previously experienced trajectories. Here, temporally structured replay of place cell activity during REM sleep is modeled in a large‐scale network simulation of grid cells, place cells and head direction cells. During simulated waking behavior, the movement of the simulated rat drives activity of a population of head direction cells that updates the activity of a population of entorhinal grid cells. The population of grid cells drives the activity of place cells coding individual locations. Associations between location and movement direction are encoded by modification of excitatory synaptic connections from place cells to speed modulated head direction cells. During simulated REM sleep, the population of place cells coding an experienced location activates the head direction cells coding the associated movement direction. Spiking of head direction cells then causes frequency shifts within the population of entorhinal grid cells to update a phase representation of location. Spiking grid cells then activate new place cells that drive new head direction activity. In contrast to models that perform temporally compressed sequence retrieval similar to sharp wave activity, this model can simulate data on temporally structured replay of hippocampal place cell activity during REM sleep at time scales similar to those observed during waking. These mechanisms could be important for episodic memory of trajectories.
The role of spatial information in advance task‐set control: an event‐related potential study
Authors: Astle D. E. , Jackson G. M. , Swainson R. 
Published: October 2008

AbstractTask‐switching has proved to be a fruitful paradigm for studying cognitive control mechanisms. Interestingly, this avenue of study has revealed that subjects are, to some degree, able to bring about a change in task‐set prior to the performance of that task (provided that they are given advance warning of the upcoming task, for instance in the form of a cue). Event‐related potentials (ERPs) have proved to be a good way of measuring these rapid anticipatory control processes. To explore these processes further, the current study examined the relationship between the availability of spatial information and cue‐locked task‐switching ERP effects. Two groups of subjects were compared: one group could separate the task‐sets on the basis of the targets’ colour (the ‘colour’ group), the second on the basis of the targets’ location (the ‘spatial’ group). The performance of both groups benefited to the same extent from advance cueing of task‐transitions (switches or repeats), yet the ERP data revealed cue‐locked (but not target‐locked) differences between the two groups. The most striking of these differences was the absence of both a late positivity over posterior scalp and a late negativity over frontal scalp when the spatial group switched between tasks. Thus, it seems unlikely that these effects index stimulus‐response ‘reconfiguration’per se– as the mappings were identical for both groups of subjects – but rather that these task‐switching processes are sensitive to how the mappings are represented.
Thermal adaptation of soil microbial respiration to elevated temperature
Authors: Bradford Mark A. , Davies Christian A. , Frey Serita D. , Maddox Thomas R. , Melillo Jerry M. , Mohan Jacqueline E. , Reynolds James F. , Treseder Kathleen K. , Wallenstein Matthew D. 
Published: October 2008

AbstractIn the short‐term heterotrophic soil respiration is strongly and positively related to temperature. In the long‐term, its response to temperature is uncertain. One reason for this is because in field experiments increases in respiration due to warming are relatively short‐lived. The explanations proposed for this ephemeral response include depletion of fast‐cycling, soil carbon pools and thermal adaptation of microbial respiration. Using a > 15 year soil warming experiment in a mid‐latitude forest, we show that the apparent ‘acclimation’ of soil respiration at the ecosystem scale results from combined effects of reductions in soil carbon pools and microbial biomass, and thermal adaptation of microbial respiration. Mass‐specific respiration rates were lower when seasonal temperatures were higher, suggesting that rate reductions under experimental warming likely occurred through temperature‐induced changes in the microbial community. Our results imply that stimulatory effects of global temperature rise on soil respiration rates may be lower than currently predicted.
Coupling of canopy and understory food webs by ground‐dwelling predators
Authors: Pringle Robert M. , Fox‐Dobbs Kena 
Published: October 2008

AbstractUnderstanding food‐web dynamics requires knowing whether species assemblages are compartmentalized into distinct energy channels, and, if so, how these channels are structured in space. We used isotopic analyses to reconstruct the food web of a Kenyan wooded grassland. Insect prey were relatively specialized consumers of either C3(trees and shrubs) or C4(grasses) plants. Arboreal predators (arthropods and geckos) were also specialized, derivingc. 90% of their diet from C3‐feeding prey. In contrast, ground‐dwelling predators preyed considerably upon both C3‐ and C4‐feeding prey. This asymmetry suggests a gravity‐driven subsidy of the terrestrial predator community, whereby tree‐dwelling prey fall and are consumed by ground‐dwelling predators. Thus, predators in general couple the C3and C4components of this food web, but ground‐dwelling predators perform this ecosystem function more effectively than tree‐dwelling ones. Although prey subsidies in vertically structured terrestrial habitats have received little attention, they are likely to be common and important to food‐web organization.
Phenotypic and genotypic characterization of multiple strains of the diazotrophic cyanobacterium, Crocosphaera watsonii, isolated from the open ocean
Authors: Webb Eric A. , Ehrenreich Ian M. , Brown Susan L. , Valois Frederica W. , Waterbury John B. 
Published: October 2008

SummaryDiazotrophic cyanobacteria have long been recognized as important sources of reduced nitrogen (N) and therefore are important ecosystem components. Until recently, species of the filamentous cyanobacterium Trichodesmium were thought to be the primary sources of fixed N to the open ocean euphotic zone. It is now recognized that unicellular cyanobacteria are also important contributors, with members of the oligotrophic genus Crocosphaera being the only cultured examples. Herein we genetically and phenotypically characterize 10 strains isolated from the tropical Atlantic and North Pacific Oceans, and show that although all of the strains are highly similar at the genetic level, with the internal transcribed sequence (ITS) region sequence varying by ∼2 bp on average, there are many unexpected phenotypic differences between the isolates (e.g. cell size, temperature optima and range, extracellular material excretion and variability in rates of nitrogen fixation). However based on the observed sequence similarity, we propose that all of these isolates are members of the genus Crocosphaera (type strain Crocosphaera watsonii WH8501), and that the phenotypic diversity we see may reflect ecologically important variation relevant for modelling N2 fixation in the oligotrophic ocean.
Morbidity and complications of protective loop ileostomy
Authors: Giannakopoulos G. F. , Veenhof A. A. F. A. , Van Der Peet D. L. , Sietses C. , Meijerink W. J. H. J. , Cuesta M. A. 
Published: October 2008

AbstractObjective  The creation of a loop ileostomy is considered suitable to protect a distal anastomosis in colorectal surgery. This technique is, however, associated with failure, complications and even mortality. The aim of this study was to quantify retrospectively the morbidity associated with an ileostomy and its subsequent closure.Method  One hundred and nineteen patients with a temporary loop ileostomy, created between January 2000 and July 2007 were retrospectively analysed from a review of patient records.Results  All ileostomies were closed after a median period of 106 days (interquartile range: 69–174 days). Stoma‐related morbidity occurred in 23 (19%) patients. After ileostomy closure, 16 major complications were seen in 14 (12%) patients and 43 minor complications occurred in 25 (21%) patients. Sixty‐three patients (53%) had neither stoma‐related morbidity or peri‐ or postoperative complications after stoma closure.Conclusion  Protective loop ileostomy was found to be associated with a high morbidity. This raises the question of the mode of identifying the specific patients with a low anastomosis who should be provided an ileostomy for protection, set against the potential complications of the formation and closure of the ileostomy.
Primary anastomosis vs Hartmann’s procedure in patients undergoing emergency left colectomy for perforated diverticulitis
Authors: Zingg U. , Pasternak I. , Dietrich M. , Seifert B. , Oertli D. , Metzger U. 
Published: October 2008

AbstractObjective  Comparison of primary anastomosis (PA) and Hartmann’s procedure (HP) in perforated diverticulitis is biased as the patient groups are different in age, comorbidity and severity of disease. Still, PA has been advocated as the procedure of choice. The aim of this study was to compare the two surgical procedures after eliminating this selection bias using a propensity score model.Method  Sixty‐five HP and 46 PA patients who underwent emergency laparotomy for perforated diverticulitis were analysed. Multivariate logistic regression using the Mannheim peritonitis index, Colorectal Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity, Charlson comorbidity index and Hinchey score was performed to determine the propensity score.Results  Patients with HP had significantly higher scores, median age and were more often on immunosuppressive medication. Unadjusted logistic regression for outcome showed a significant risk of HP vs PA for nonsurgical morbidity (odds ratio 3.25, 95% CI: 1.26–8.43; P = 0.015), but not for mortality and surgical morbidity. After adjusting for the propensity score, outcome was not significantly different. Patients with PA had a clinical leak rate of 28% and none of the patients with leakage had a protective ileostomy. Patients with PA and leak had higher Charlson scores whereas all other scores were similar to nonleak patients.Conclusion  The theory that PA is generally superior to HP cannot be supported. HP remains a safe technique for emergency colectomy in perforated diverticulitis, especially in elderly patients with multiple comorbidities. If PA is performed, a protective ileostomy must be considered.
Management of the asymptomatic primary in the palliative treatment of metastatic colorectal cancer
Authors: Clements D. , Dhruva Rao P. , Ramanathan D. , Adams R. , Maughan T. S. , Davies M. M. 
Published: October 2008

AbstractObjective  The management of the asymptomatic primary in stage IV colorectal cancer presents a dilemma. There is an increased morbidity and mortality from surgical resection. Nonresectional management of the primary is associated with the risks of obstruction, perforation or haemorrhage. Our practice in patients with stage IV disease is palliative chemotherapy and symptom control. We reviewed our nonoperatively managed patients with colorectal liver metastases in order to identify the percentage of patients requiring urgent operative interventions for symptoms related to the primary.Subjects/patients and method  A retrospective review of all patients treated for stage IV disease at our institution from 2003–2006 was undertaken. Patients were identified from multidisciplinary team (MDT) records. Demographic detail, treatment, and follow‐up data were extracted from hospital records. These were analysed with Microsoft Excel.Results  Thirty‐seven patients were identified. 26 Male:11 Female. Median age 63 years (range 38–78). The median survival from diagnosis was 14 months. Three (8%) patients developed obstruction whilst having palliative chemotherapy. Two required a defunctioning stoma, and one was treated by means of a stent. There were no similarities between these three patients in terms of age, sex, site or stage of primary, volume of liver metastases, and alkaline phosphatase (ALP) or carcinoembryonic antigen (CEA) levels.Conclusion  Of 37 patients initially treated palliatively for stage IV colorectal cancer, 92% required no surgical treatment of their primary. Therefore it is the experience of this MDT that it is acceptable to treat such patients in an expectant manner. It is not possible to predict those patients, likely to require surgical intervention.
Rectal cancer with macroscopic peritoneal involvement – clinical challenges and consequences
Authors: Sigurdsson H. K. , Kørner H. , Dahl O. , Skarstein A. , Søreide J. A. ,   On behalf of The Norwegian Colorectal Cancer Group
Published: October 2008

AbstractObjective  In gastrointestinal cancer, serosal involvement indicates advanced disease. We looked at the possible role of clinical peritoneal involvement (CPI) in local recurrences (LRs) and the overall survival of patients with rectal cancer (RC).Method  Between 1993 and 2002, 6404 patients were diagnosed with RC. Based on macroscopic findings at surgery and corresponding histological findings, 166 patients (3%) had CPI. Surgery was stratified according to type and extent of operation: as resective or nonresective surgery and as curative (R0) or noncurative (R1 or R2) resection.Results  The presence of CPI was a negative factor for survival with a median of 15 months (95% CI, 12–19) in the presence of CPI compared with 65 months (95% CI, 61–70) without it (P < 0.001). In R0 resections, the median survival was 97 months (95% CI, 90–102) in patients without CPI compared with 48 months (95% CI, 22–74) in patients with CPI (P < 0.001). In R1 or R2 resections, the median survival was 16 months (95% CI, 15–17) in the absence of CPI and 9 months (95% CI, 8–10) in the presence of CPI. The LR rate in patients without CPI was 10.2% compared with 15.7% in patients with CPI (P = 0.022).Conclusions  Clinical peritoneal involvement is a significant detrimental prognostic factor for the LR of RC and survival in the absence of metastases. Observations from this large national cohort add to what is known about peritoneal involvement. Diagnosed CPI should be taken into consideration when adjuvant treatment strategies are addressed.
Prostate‐specific antigen flare phenomenon with docetaxel‐based chemotherapy in patients with androgen‐independent prostate cancer
Authors: Sella Avishay , Sternberg Cora N. , Skoneczna Iwona , Kovel Svetlana 
Published: October 2008

OBJECTIVETo evaluate the prostate‐specific antigen (PSA) ‘flare’ phenomenon in patients with androgen‐independent prostate cancer (AIPC) treated with docetaxel, as flare is a known effect of androgen‐deprivation therapy in hormone‐dependent prostate cancer.PATIENTS AND METHODSThe charts of 56 patients who received docetaxel‐based chemotherapy in three different centres from August 1999 to August 2007 were reviewed retrospectively. The biochemical response was characterized according to the Bubley criteria. There was an immediate PSA response (PSA decline ≥ 50%) in 23 (41%) patients, PSA stabilization (PSA decline < 50%) in 16 (29%) and PSA progression in nine (16%). There was also a fourth response, i.e. PSA flare, defined as an increase in PSA level with no symptomatic progression, after starting docetaxel‐based chemotherapy administered every 3 weeks.RESULTSEight (14%) patients with PSA flare were identified; all had osseous disease and five had additional soft‐tissue disease. The PSA flare lasted a median (range) of 21 (21–42) days and it spread over a median of 1 (1–2) cycles. The temporary PSA surge exceeded baseline values by a median (range) of 61.5 (12–404)%. There was a subsequent PSA response in six of the eight patients and PSA stabilized in the remaining two. Patients with flare received a median of 8.5 (5–12) treatment cycles, vs a median of 8 (2–12) in the immediate PSA response group (P = 0.103, Student’s t‐test). The Response Evaluation Criteria in Solid Tumors criteria evaluation showed one patient with a partial response and six with stable disease. The median survival of patients with PSA flare was 12.5 months, while that of the immediate PSA responders was 20.1 months (not statistically significant, P = 0.168, log‐rank test).CONCLUSIONOf patients with AIPC, 14% had an initial PSA flare after starting docetaxel‐based chemotherapy. The occurrence of PSA flare had no effect on treatment duration or outcome. With lack of clinical progression, docetaxel‐based chemotherapy should be administered for at least two 3‐week cycles before further decisions are made about efficacy.
The NCEP‐ATPIII but not the IDF criteria for the metabolic syndrome identify Type 2 diabetic patients at increased risk of chronic kidney disease
Authors: Luk A. O. Y. , Ma R. C. W. , So W‐Y. , Yang X‐L. , Kong A. P. S. , Ozaki R. , Ko G. T. C. , Chow C‐C. , Cockram C. S. , Chan J. C. N. , Tong P. C. Y. 
Published: October 2008

AbstractAim  To examine the association between chronic kidney disease (CKD) and the metabolic syndrome (MetS) using both International Diabetes Federation (IDF) and National Cholesterol Education Program's Adult Treatment Panel III (NCEP‐ATPIII) definitions in Chinese subjects with Type 2 diabetes.Methods  Subjects with Type 2 diabetes were categorized according to the presence or absence of MetS by IDF or NCEP‐ATPIII criteria. CKD was considered present if glomerular filtration rate, calculated using the abbreviated equation developed by the Modification of Diet in Renal Disease study with Chinese modification, was < 60 ml/min per 1.73 m2. Multivariate logistic regression analysis of the association between CKD and MetS by either definition was performed.Results  Of 6350 subjects (mean age 55.1 ± 13.3 years), 3439 (54.2%) and 3204 (50.5%) had MetS by IDF and NCEP‐ATPIII definitions, respectively. Using the IDF definition, the presence of MetS was not associated with CKD [odds ratio (OR) 0.96, 95% confidence interval (CI) 0.71, 1.29, P = 0.784]. In contrast, the association with CKD was significant when MetS was defined by the NCEP‐ATPIII definition (OR 1.75, 95% CI 1.37, 2.24, P < 0.001). In subjects who did not have MetS (n = 2911) as defined by IDF criteria, 997 fulfilled the MetS criteria of NCEP‐ATP III. The association with CKD was stronger, after adjustment for covariates, in these subjects (OR 1.42, 95% CI 1.03, 1.97, P = 0.032) compared with subjects who met IDF criteria of MetS.Conclusion  In Type 2 diabetes, NCEP‐ATPIII, but not the IDF definition of MetS, identifies a subgroup of patients who have a higher risk of CKD.
Interspecific competition influences reproduction in spotted hyenas
Authors: Watts H. E. , Holekamp K. E. 
Published: October 2008

AbstractInterspecific competition among carnivores is an important determinant of predator population dynamics, and it may also affect lower trophic levels. Whereas considerable research has focused on effects of interspecific competition on threatened carnivore populations, here we examine the effects of interspecific competition on the most abundant large carnivore in Africa, the spotted hyena Crocuta crocuta. Specifically, we compared two populations of spotted hyenas to examine the sources of variation in fitness, including effects of competition with lions Panthera leo. Hyenas living in Amboseli National Park and the Masai Mara National Reserve, Kenya, were monitored from 2003 to 2005 and 1988 to 1992, respectively. Females reproduced at significantly higher rates in Amboseli, due to shorter lactation periods, though neither juvenile survival nor litter size differed between populations. Differences in reproduction were estimated to result in 24% greater lifetime reproductive success among Amboseli than among Mara females. We then tested alternative ecological hypotheses to explain these differences in fitness measures between populations. We found little support for hypotheses suggesting that population differences were due to variation in prey availability or dispersion, or to intraspecific competition either within or between hyena groups. Our results were most consistent with the hypothesis that population differences were due to variation in interspecific competition with lions. Hyenas in Amboseli lived at lower lion density, enjoyed higher rates of food intake despite less abundant prey, and scavenged more food from lions than did Mara hyenas. Our results indicate that competition with lions operated primarily via food competition, rather than direct killing, to generate the fitness differences.
Rit signaling contributes to interferon‐γ‐induced dendritic retraction via p38 mitogen‐activated protein kinase activation
Authors: Andres Douglas A. , Shi Geng‐Xian , Bruun Donald , Barnhart Chris , Lein Pamela J. 
Published: October 2008

AbstractThe proinflammatory cytokine interferon‐γ (IFNγ) alters neuronal connectivity via selective regressive effects on dendrites but the signaling pathways that mediate this effect are poorly understood. We recently demonstrated that signaling by Rit, a member of the Ras family of GTPases, modulates dendritic growth in primary cultures of sympathetic and hippocampal neurons. In this study, we investigated a role for Rit signaling in IFNγ‐induced dendritic retraction. Expression of a dominant negative Rit mutant inhibited IFNγ‐induced dendritic retraction in cultured embryonic rat sympathetic and hippocampal neurons. In pheochromacytoma cells and hippocampal neurons, IFNγ caused rapid Rit activation as indicated by increased GTP binding to Rit. Silencing of Rit by RNA interference suppressed IFNγ‐elicited activation of p38 MAPK in pheochromacytoma cells, and pharmacological inhibition of p38 MAPK significantly attenuated the dendrite‐inhibiting effects of IFNγ in cultured sympathetic and hippocampal neurons without altering signal transducer and activator of transcription 1 activation. These observations identify Rit as a downstream target of IFNγ and suggest that a novel IFNγ‐Rit‐p38 signaling pathway contributes to dendritic retraction and may, therefore, represent a potential therapeutic target in diseases with a significant neuroinflammatory component.
Beyond Anemia: The Clinical Impact of the Physiologic Effects of Erythropoietin
Authors: Diskin Charles J. , Stokes Thomas J. , Dansby Linda M. , Radcliff Lautrec , Carter Thomas B. 
Published: October 2008

AbstractAlthough we have known that oxygen tension affects erythrocyte production since the 19th century, we have only recently begun to understand many subtleties of erythropoietin (EPO) physiology. EPO administration has allowed hundreds of thousands of patients to avoid transfusions. With the beneficial effects so apparent a detailed understanding of the full clinical physiology of this plasma factor seemed less important. However, the unanticipated increase in mortality found in recent randomized studies is prompting a reassessment of this view. We will review what is known about the physiology of this plasma factor that, it is now clear, is more than just an erythrocyte production factor.