bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolution of the Single‐Pool Urea Kinetic Model
Authors: Gotch Frank A. 
Published: March 2003

ABSTRACTOur interest in urea kinetic modeling (UKM) was stimulated some 30 years ago at the time of the advent of hollow fiber kidneys with greatly improved urea transport. This led to examination of the interaction between time and clearance in computing the dialysis dose. In early studies a fixed‐volume single‐pool UKM was used but this frequently gave spurious high volumes and led to the advent of the variable‐volume single‐pool model. The role of volume calculation in assessment of the delivered dialysis dose and the value of normalized protein catabolic rate (nPCR) calculation are reviewed. More recently quantification of double‐pool effects has become simplified and now is widely used for UKM. The National Cooperative Dialysis Study (NCDS) resulted in the concept of dose quantification by Kt/V. This is reviewed, including the controversy surrounding interpretation of the NCDS. Currently there is great interest in more frequent dialysis, 4–6 days/week. The development of a new dose parameter, the standard Kt/V (stdKt/V), to enable quantitative comparison of dose with widely varying dose schedules is discussed.
Imaging in the Dialysis Patient: The Pathology of Dialysis
Authors: Freemont A. J. 
Published: March 2003

AbstractThere are a number of pathologies that are associated with the development of renal failure. Once renal function has deteriorated beyond a point where life is not sustainable without dialysis, new sets of pathologic processes develop. These are, in part, related to the continuation of poor renal function and to the process of dialysis itself. This article addresses the processes that are believed to be due to dialysis, among which are disorders of bone, deposition of metals and amyloid within a number of tissues, and local problems such as inflammation and tumors related to the dialysis site.
Biofilms and Infection in Dialysis Patients
Authors: Dasgupta Mrinal K. 
Published: March 2003

AbstractBiofilm bacterial infections are implicated in most human bacterial infections and are also common in patients undergoing treatment with hemodialysis and peritoneal dialysis. Skin bacteria, which grow into microcolonies with biofilm formation in dialysis environments, are implicated in most of these infections. Dissemination of bacterial biofilms in hemodialysis patients induces bacteremia and endotoxemia. In peritoneal dialysis patients, biofilm causes peritonitis and catheter‐related infections with consequent loss of catheters and technique failure. Effective strategies for the diagnosis, intervention, and prevention of biofilm‐related infections in dialysis patients are described in this review.
Intermediate‐Term Outcome with Radical Prostatectomy for Localized Prostate Cancer: The Cleveland Clinic Experience
Authors: Clark Peter E. , Levin Howard S. , Kupelian Patrick A. , Reddy Chandanna , Zippe Craig D. , Klein Eric A. 
Published: March 2003

ABSTRACTPurpose: We examined the results after radical prostatectomy (RP) for clinically localized prostate cancer to determine the 5‐ and 8‐year disease‐specific and biochemical relapse‐free survival (bRFS), and the clinical and pathologic variables that predict biochemical failure.Materials and Methods: Nine hundred six patients underwent RP for clinically localized prostate cancer between 1990 and 1999. No patient received neoadjuvant or adjuvant therapy. The mean age was 61.9 years (range 40–77 years). The mean preoperative prostate specific antigen (PSA) level was 8.7 ng/ml (range 0.3–54.0). Seventy‐six percent of patients had a biopsy Gleason score ≤6, and 49% had disease at clinical Stage T1c. Eighteen percent of patients reported a family history of prostate cancer. Actuarial bRFS rates were calculated using Kaplan‐Meier analysis.Results: Pathologic analysis showed that 43% of patients had extracapsular extension, 44% had pathologic Gleason scores ≤6, 23% had positive margins, 8.9% had seminal vesicle invasion, and 1.9% had lymph node metastases. At a mean follow‐up of 44 months (range 1–114), the 5‐ and 8‐year cancer‐specific survival rates were 97% and 95%, respectively. The actuarial 5‐ and 8‐year bRFS rates were 81% and 76%, respectively. Patients with organ‐confined disease had a 100% cancer‐specific survival rate and a 92% bRFS rate at both 5 and 8 years. On multivariate analysis, a positive family history (p = 0.019), clinical stage (p = 0.014), preoperative PSA level (p < 0.001), pathologic Gleason score (p < 0.001), extracapsular extension (p = 0.03), positive margins (p < 0.0001), and seminal vesicle invasion (p = 0.0003) were all independent predictors of bRFS.Conclusion: Radical prostatectomy for patients with localized prostate cancer has a high rate of cure for appropriately selected patients.
Sustained Activation of Extracellular Signal‐Regulated Kinase (ERK) Signaling in Human Prostate Cancer LNCaP Cells Depleted of Androgen
Authors: Drew Lisa , Fine Robert L. , Raffo Anthony J. , Petrylak Daniel P. 
Published: March 2003

ABSTRACTObjectives: The mitogen‐activated protein kinase (MAPK) cascade is involved in the control of cell growth and differentiation. In this study, we have investigated the effect of androgen withdrawal on this pathway and its potential role in the induction of neuroendocrine (NE) differentiation. For this purpose, we used the androgen‐sensitive human prostate cancer LNCaP cells as an in vitro model. Methods and Results: The incubation of LNCaP cells for 6 days in medium, either free of serum or supplemented with serum depleted of steroids (i.e., charcoal‐stripped serum), resulted in NE differentiation as determined by growth arrest, the formation of neurites, and an increase in neuron‐specific enolase protein expression. Sustained extracellular‐regulated kinase (ERK) phosphorylation/activity and enhanced ERK/MAPK kinase (MEK) activity also were observed on serum or steroid withdrawal. A synthetic androgen, mibolerone, blocked both NE differentiation and ERK phosphorylation induced by the incubation of the cells in steroid‐depleted medium, thus confirming androgen specificity. Furthermore, a culture of LNCaP cells in complete medium supplemented with a 5‐α‐reductase inhibitor, finasteride, also induced NE differentiation and ERK phosphorylation. This implicates depletion of the principal prostatic androgen, dihydrotestosterone, as the specific mediator of these effects. In contrast to ERK, the phosphorylation status of the stress‐activated MAPK members c‐Jun N‐terminal kinase and p38 was not altered by steroid withdrawal. The MEK inhibitor U0126 was used to study the potential role of ERK in regulating NE differentiation. However, U0126 did not reverse NE differentiation associated with steroid depletion, even though ERK phosphorylation was suppressed. The role of erb B tyrosine kinase receptors in mediating ERK phosphorylation during steroid depletion also was investigated. erb B1 protein levels decreased, erb B3 protein levels and phosphorylation remained unaltered, and erb B2 phosphoprotein levels increased after steroid depletion. Stable expression of an intracellular antibody to erb B2, however, did not prevent the up‐regulation of ERK phosphorylation that is associated with steroid depletion.Conclusions: Androgen depletion induces sustained erb B‐independent ERK signaling in LNCaP cells, however, this pathway is not essential for the associated NE differentiation.
Development of a Structural Equation Model for Causal Relationships Among Arteriosclerosis Risk Factors
Authors: Oh HyunSoo , Seo WhaSook 
Published: March 2003

The purpose of this study was to clarify the dynamic causal relationships among arteriosclerotic risk factors, including age, smoking, alcoholic consumption, exercise, hypercholesterolemia, hypertriglyceridemia, and hypertension. Data were collected from the medical records of 400 male clients who visited a university hospital located in Inchon, Korea, from May 1996 to December 1996 for physical examinations. The Lineal Structural Relationships 8 program was used to verify the fitness of the hypothetical model to data.All of the fit statistics, except the Chi‐square value, showed that the hypothetical model was well fitted to the data. Seven percent of obesity was explained by the variables of age, smoking, alcohol consumption, and exercise. Sixty percent of hyperlipidemia could be explained by the variables of age, smoking, exercise, and obesity. And 22% of hypertension was explained by the variables of age, smoking, alcohol consumption, exercise, and hyperlipidemia. Our results showed that these risk factors were directly and indirectly interrelated, and lifestyle variables (smoking, alcohol consumption, and exercise) influence almost all of arteriosclerotic risk factors.
Water and Nutrient Outflow Following the Ecological Restoration of a Ponderosa Pine‐Bunchgrass Ecosystem
Authors: Kaye Jason P. , Hart Stephen C. , Cobb Richard C. , Stone Joseph E. 
Published: March 2003

AbstractIn the late 1800s, fire suppression, livestock grazing, and a wet and warm climate led to an irruption of pine regeneration inPinus ponderosaLaws. (ponderosa pine) forests of the southwestern United States. Pines invaded bunchgrass openings, causing stand structure changes that increased the number of stand‐replacing fires. Ecological restoration, via thinning and prescribed burning, is being used to decrease the risk of stand‐replacing fires and ameliorate other effects of pine invasion. The effects of aboveground restoration on belowground processes are poorly understood. We used a hydrologic model and soil water nutrient concentrations, measured monthly below the rooting zone, to estimate restoration effects on nutrient losses by leaching from a mature ponderosa pine forest near Flagstaff, Arizona. Replicated restoration treatments included thinning to pre‐1880 stand densities (partial restoration), thinning plus forest floor fuel reduction followed by a prescribed burn (complete restoration), and an untreated control. Water outflow occurred only between January and May and was lowest from the control (47 and 28 mm in 1995 and 1996) and highest from the partial restoration treatment (67 and 59 mm in 1995 and 1996). The concentrations (typically <0.10 mg/ L) and estimated annual losses (<0.02 kg/ha) of NH4+‐N, PO43−‐P, and organic P were similar among treatments. Nitrate and organic N concentrations were as high as 0.80 mg N/L; however, these concentrations and estimated annual losses (<0.13 kg N/ha) were similar among treatments. Our results suggest that restoration will not enhance nutrient loss by leaching or alter stream chemistry in ponderosa pine forests.
A Historical Perspective and Future Outlook on Landscape Scale Restoration in the Northwest Wisconsin Pine Barrens
Authors: Radeloff Volker C. , Mladenoff David J. , Boyce Mark S. 
Published: March 2003

AbstractThe concurrent discussions of landscape scale restoration among restoration ecologists, and of historic disturbance pattern as a guideline for forest management among forest scientists, offer a unique opportunity for collaboration between these traditionally separated fields. The objective of this study was to review the environmental history, early restoration projects, and current plans to restore landscape patterns at broader scales in the 450,000 ha northwest Wisconsin Pine Barrens. The Pine Barrens offer an example of a landscape shaped by fire in the past. In northwestern Wisconsin historically the barrens were a mosaic of open prairie, savanna, and pine forests on very poor, sandy soils. The surrounding region of better soils was otherwise heavily forested. Six restoration sites have been managed since the middle of this century using prescribed burns to maintain the open, barrens habitat. However, these sites are not extensive enough to mimic the shifting mosaic of large open patches previously created by fire. Extensive clear‐cuts may be used as a substitute for these large fire patches so that presettlement landscape patterns are more closely approximated in the current landscape. We suggest that such silvicultural treatments can be suitable to restore certain aspects of presettlement landscapes, such as landscape pattern and open habitat for species such as grassland birds. We are aware that the effects of fire and clear‐cuts differ in many aspects and additional management tools, such as prescribed burning after harvesting, may assist in further approximating the effect of natural disturbance. However, the restoration of landscape pattern using clear‐cuts may provide an important context for smaller isolated restoration sites even without the subsequent application of fire, in this formerly more open landscape.
Translocations as a Tool for Restoring Populations of Bighorn Sheep
Authors: Singer Francis J. , Papouchis Christopher M. , Symonds Kate K. 
Published: March 2003

AbstractWe analyzed factors that contributed to the success of 100 translocations of bighorn sheep within six western states between 1923 and 1997. We categorized the populations as unsuccessful (i.e., extirpated or remnant, <29 animals), moderately successful (30–99 animals), and successful (100–350 animals) by the end of the study period in 1997. Thirty of the translocated populations were unsuccessful (n= 13 were extirpated andn= 17 were remnant), 29 were moderately successful, and 41 were successful (21 ± 1.3 [SE] years of information per translocation). Translocations were less successful when domestic sheep were located within 6 km of the known bighorn sheep use areas (logistic regression,p= 0.052). Grazing of cattle on the same range also negatively influenced success (p= 0.004). Use of indigenous versus previously translocated source stocks increased success (p= 0.084). The translocation was twice as likely to be successful when indigenous herds were used as sources (p= 0.043), but mixing genetic stocks (p= 0.381) or later additional augmentations did not influence success (p= 0.095). Annual migrations by newly established translocated populations increased success (p= 0.014). We recommend translocations of founder groups of bighorn sheep from indigenous sources into large patches of habitat that promote movements and migrations, and with no domestic sheep present in the area.
Effects of Disease, Dispersal, and Area on Bighorn Sheep Restoration
Authors: Gross John E. , Singer Francis J. , Moses Michael E. 
Published: March 2003

AbstractWe simulated population dynamics of bighorn sheep (Ovis canadensis) inhabiting six discrete habitat patches in the Badlands ecosystem, South Dakota. Modeled populations were subjected to a range of potential management actions and rates of disease‐causing infection. Simulated disease varied in severity from mild (∼12% mortality) to severe (∼67% mortality), with infections imposed once, at regular intervals, or with a fixed probability each year. In the absence of disease, 200‐year extinction rates were uniformly low and insensitive to changes in colonization rate or area of suitable habitat. A single infection, accompanied by change in the area of suitable habitat or colonization rate, resulted in extinction rates of up to 40%, and large changes in average population size (up to 10‐fold with changes in area; 4‐fold with changes in colonization rate). Simulations with multiple infections, which are probably most realistic, generally resulted in extinction rates that exceeded 20% over a 200‐year period. Model results clearly showed that efforts directed toward reducing the frequency or severity of disease are of highest priority for improving the success of attempts to restore bighorn sheep populations. Increases in areas of suitable habitat or improvements to corridors between existing habitat patches were far less likely to improve persistence of simulated sheep populations than reductions in the impact of disease. Although theory predicts that enhanced movements may exacerbate effects of disease, increased colonization rates resulted in relatively small but consistent increases in persistence and average population size for all combinations of parameters we examined.
Degraded Softwater Lakes: Possibilities for Restoration
Authors: Brouwer E. , Roelofs J. G. M. 
Published: March 2003

AbstractIn the Netherlands, the characteristic flora of shallow softwater lakes has declined rapidly as a consequence of eutrophication, alkalization and acidification. The sediment of most lakes has become nutrient rich and anaerobic. We expected that, if a vital seed bank was still present, restoration of the original water quality and sediment conditions would lead to the return of softwater macrophytes. The restoration of 15 degraded, shallow, softwater lakes in the Netherlands was monitored from 1983 to 1998. In eutrophied as well as in acidified lakes, removal of accumulated organic matter from the sediment and shores was followed by rapid recolonization of softwater macrophytes present in the seedbank. After isolation from alkaline water and subsequent mud removal, this recovery was also observed in alkalized lakes. Further development of softwater vegetation correlated strongly with the water quality. When renewed eutrophication was successfully prevented, softwater macrophytes could expand. However, in acidified lakes, Juncus bulbosus and Sphagnum species became dominant after restoration. Liming of an acidified lake was followed by re‐acidification within 3 years. Recolonization by softwater macrophytes was inhibited by high turbidity of the water column and spreading of large helophytes on the shore. As an alternative, controlled inlet of alkaline, nutrient‐poor groundwater was studied in a few lakes. The pH of those lakes increased, the carbon and nitrogen availability decreased and softwater macrophytes returned. Successful restoration has contributed considerably to maintaining biodiversity in softwater lakes in the Netherlands.
Achieving Restoration Success: Myths in Bottomland Hardwood Forests
Authors: Stanturf John A. , Schoenholtz Stephen H. , Schweitzer Callie Jo , Shepard James P. 
Published: March 2003

AbstractRestoration of bottomland hardwood forests is the subject of considerable interest in the southern United States, but restoration success is elusive. Techniques for establishing bottomland tree species are well developed, yet problems have occurred in operational programs. Current plans for restoration on public and private land suggest that as many as 200,000 hectares could be restored in the Lower Mississippi Alluvial Valley alone. The ideal of ecological restoration is to reestablish a completely functioning ecosystem. Although some argue that afforestation is incomplete restoration, it is a necessary and costly first step but not an easy task. The 1992 Wetlands Reserve Program in Mississippi, which failed on 90% of the area, illustrates the difficulty of broadly applying our knowledge of afforestation. In our view, the focus for ecological restoration should be to restore functions, rather than specifying some ambiguous natural state based on reference stands or pre‐settlement forest conditions. We view restoration as one element in a continuum model of sustainable forest management, allowing us to prescribe restoration goals that incorporate landowner objectives. Enforcing the discipline of explicit objectives, with restoration expectations described in terms of predicted values of functions, causal mechanisms and temporal response trajectories, will hasten the development of meaningful criteria for restoration success. We present our observations about current efforts to restore bottomland hardwoods as nine myths, or statements of dubious origin, and at best partial truth.
Responses of Jeffrey Pine on a Surface Mine Site to Fertilizer and Lime
Authors: Walker R. F. 
Published: March 2003

AbstractControlled‐release fertilization with two formulations, Forestcote 22‐4‐6 + Minors and Gromax 21‐6‐2 + Minors, and dolomitic lime were evaluated for their capacity to facilitate establishment and enhance nutrition of bareroot Jeffrey pine (Pinus jeffreyiGrev. & Balf.) on an acidic Sierra Nevada surface mine. All amendments were applied at outplanting to the backfill of augered planting holes, with a low rate of 8 g and a high rate of 16 g per seedling for the two fertilizer formulations, whereas a single rate of 30 g was used for lime. Liming induced excessive seedling mortality throughout the study, whereas both fertilizer formulations also reduced survival but only as an interactive effect with the lime amendment. Growth stimulation by the fertilizer applications was readily apparent after three growing seasons, with the response to the high rate surpassing that to the low rate and the response to the Forestcote formulation exceeding that to Gromax. Conversely, the lime amendment depressed seedling growth, and it is likely that a propensity to exacerbate the stress imposed by dry growing season soils through interference with water uptake accounts for the overall poor performance of the seedlings that received this amendment. Improved N and P nutrition, with the former likely the most critical, was largely responsible for the growth stimulation resulting from fertilization. However, this treatment also suppressed the absorption of certain micronutrients as well as that of Al, and the amelioration of potential phytotoxicities may have also contributed to the favorable performance of fertilized seedlings. Further evidence for this conclusion was supplied by base cation/metallic element molar ratios involving Al and Mn, which were frequently increased by fertilization. In contrast, the influence of the lime amendment on seedling nutrition was marginal, with positive responses too infrequent to improve seedling performance.