bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rathke cleft cyst apoplexy: a newly characterized distinct clinical entity
Authors: Chaiban Joumana T. , Abdelmannan Dima , Cohen Mark , Selman Warren R. , Arafah Baha M. 
Published: May 2010

Object
Although most Rathke cleft cysts (RCCs) remain asymptomatic, some present with compression of surrounding structures and pituitary hormone dysfunction. A rare, but distinct presentation of the RCC includes hemorrhage into the cyst—a presentation that mimics the clinical syndrome of pituitary tumor apoplexy. The objective of this article is to present the authors' experience on the prevalence and the clinical, biochemical, pathological, and imaging characteristics of hemorrhage into an RCC and review published reports on this entity.

Methods
An institutional database for patients with pituitary masses was reviewed and data on cases involving surgery for a subsequently documented RCC were identified. Patients with documented hemorrhage within the RCC were included in the analysis. Documentation included intraoperative visualization of hemorrhage by the surgeon and/or pathological confirmation of hemorrhage within the RCC. The clinical, biochemical, pathological, and imaging characteristics of these patients were extracted from the database. All published data on RCC were also reviewed and confirmed cases of hemorrhage were extracted and included in the review.

Results
A total of 11 cases with hemorrhage within an RCC were identified to have been managed at the authors' institution over a 10-year span. This figure represented 20% of all surgically treated cases of RCC from that period. Among published reports, a total of 10 confirmed cases were evaluated. The clinical presentation of patients with hemorrhage within an RCC are classical and include sudden onset of severe headache—or a sudden increase in headache severity—associated with visual disturbances, impairment in pituitary function, and occasionally alterations in mental status. Leakage of the cystic contents into the subarachnoid space can occur rarely and may lead to associated chemical meningitis. There are no known precipitating factors for this phenomenon. The clinical presentation of such patients is difficult to distinguish from that of patients with pituitary tumor apoplexy. However, patients with RCC apoplexy often present with less severe symptoms, have a lower prevalence of pituitary dysfunction, and generally have smaller mass lesions than those with pituitary tumor apoplexy. Management of patients with RCC apoplexy is similar to that of those with pituitary tumor apoplexy. Surgery can provide definitive diagnosis and relief of symptoms and often leads to recovery from hypopituitarism. All patients with this syndrome require long-term follow-up to treat any residual sequelae.

Conclusions
This article provides the first thorough review and characterization of patients with hemorrhage within an RCC. Based on the clinical manifestations of this presentation, we recommend using the term “Rathke cleft cyst apoplexy” to describe the syndrome.
Clonal resistance analyses of HIV type-1 after failure of therapy with didanosine, lamivudine and tenofovir
Authors: Barnas Douglas , Koontz Dianna , Bazmi Holly , Bixby Christian , Jemsek Joseph , Mellors John W 
Published: May 2010

Background The rapid failure of initial therapy with combinations of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) that exclude zidovudine has not been fully explained by standard virus population analyses of HIV type-1 (HIV-1) drug resistance. We therefore investigated HIV-1 genotype and phenotype at the single genome level in samples from patients on a failing regimen of tenofovir (TNV), didanosine (ddI) and lamivudine (3TC). Methods Single genome sequencing was performed on 9 failure samples containing both K65R and M184V mutations by standard genotype, either as wild-type/mutant mixtures (6/9) or as mutant only (3/9). Recombinant clones with different combinations of observed mutations were generated and tested for NRTI susceptibility. Results Of the 204 single genome sequences analysed, 50% were K65R/M184V double mutants, 38% were M184V single mutants, 10% were M184I single mutants and only 1% (2 sequences) were K65R single mutants. Phenotypic testing of recombinant clones showed a significant increase in resistance for double mutants: mean fold resistance to abacavir, ddI and TNV was 6.5, 4.3 and 1.6 for K65R/M184V double mutants versus 2.5, 1.9 and 0.6 for M184V single mutants, respectively ( P<0.001). Conclusions Mutants with K65R and M184V linked on the same genome were the most common HIV-1 variants in samples analysed from patients failing TNV, ddI and 3TC with both mutations detected by standard genotype. The double mutant exhibited reduced susceptibility to all three NRTIs in the regimen. This resistant phenotype, resulting from just two linked point mutations, likely contributes to rapid failure of NRTI combinations that exclude zidovudine.
Evaluation of the in vitro anti-HBV activity of clevudine in combination with other nucleoside/ nucleotide inhibitors
Authors: Niu Congrong , Bao Haiying , Tolstykh Tatiana , Steuer Holly M Micolochick , Murakami Eisuke , Korba Brent , Furman Phillip A 
Published: May 2010

Background To reduce the incidence of drug resistance and to maintain viral suppression, patients chronically infected with HBV might require combination therapy using two or more drugs with different resistance pro-files. We investigated the activity of clevudine (CLV) in combination with other nucleoside/nucleotide analogues to determine if these combinations were compatible in vitro. Methods Using the HepAD38 cell line, which expresses wild-type HBV, and a real-time PCR assay, we tested the anti-HBV activity of CLV in combination with entecavir, lamivudine, adefovir, tenofovir and telbivudine (TBV). We evaluated the uptake and phosphorylation of CLV in the presence of TBV, using HepAD38 cells and primary hepatocytes to determine the effect of TBV on the phosphorylation of CLV and vice versa. Phosphorylation of TBV and CLV to their corresponding monophosphate by deoxycytidine kinase, thymidine kinase-1 and thymidine kinase-2, and the phosphorylation of TBV monophosphate and CLV monophosphate by thymidylate kinase was evaluated and compared. Results When CLV was combined with entecavir, lamivudine, adefovir or tenofovir, a synergistic antiviral effect was observed; however, the combination of CLV and TBV gave an antagonistic antiviral response. The results of in vitro metabolism and enzyme studies suggest that the antagonism observed with the CLV/TBV combination involves competition for uptake and phosphorylation. Conclusions The results of our studies demonstrate that combination treatments can provide enhanced antiviral activity and, when used in conjunction with appropriate metabolic investigations, provide a rational basis for the design and development of combination regimens for treating chronic HBV infection.
CD4+ T-cell-guided structured treatment interruptions of antiretroviral therapy in HIV disease: Projecting beyond clinical trials
Authors:   CEPAC-International Investigators, Yazdanpanah Yazdan , Wolf Lindsey L , Anglaret Xavier , Gabillard Delphine , Walensky Rochelle P , Moh Raoul , Danel Christine , Sloan Caroline E , Losina Elena , Freedberg Kenneth A 
Published: May 2010

Background International trials have shown that CD4+ T-cell-guided structured treatment interruptions (STI) of antiretroviral therapy (ART) lead to worse outcomes than continuous treatment. We simulated continuous ART and STI strategies with higher CD4+ T-cell interruption/reintroduction thresholds than those assessed in actual trials. Methods Using a model of HIV, we simulated cohorts of African adults with different baseline CD4+ T-cell counts (≤200; 201-350; and 351-500 cells/μl). We varied ART initiation criteria (immediate; CD4+ T-cell count <350 cells/μl or ≥350 cells/μl with severe HIV-related disease; and CD4+ T-cell count <200 cells/μl or ≥200 cells/μl with severe HIV- related disease), and ART interruption/reintroduction thresholds (350/250; 500/350; and 700/500 cells/μl). First-line therapy was non- nucleoside reverse transcriptase inhibitor (NNRTI)-based and second-line therapy was protease inhibitor (PI)-based. Results STI generally reduced life expectancy compared with continuous ART. Life expectancy increased with earlier ART initiation and higher interruption/reintroduction thresholds. STI reduced life expectancy by 48–69 and 11–30 months compared with continuous ART when interruption/reintroduction thresholds were 350/250 and 500/350 cells/μl, depending on ART initiation criteria. When patients interrupted/reintroduced ART at 700/500 cells/μl, life expectancies ranged from 2 months lower to 1 month higher than continuous ART. STI-related life expectancy increased with decreased risk of virological resistance after ART interruptions. Conclusions STI with NNRTI-based regimens was almost always less effective than continuous treatment, regardless of interruption/reintroduction thresholds. The risks associated with STI decrease only if patients start ART earlier, interrupt/reintroduce treatment at very high CD4+ T-cell thresholds (700/500 cells/μl) and use first-line medications with higher resistance barriers, such as PIs.
Genotypic and phenotypic evolution of HIV type-1 protease during in vitro sequential or concomitant combination of atazanavir and amprenavir
Authors: Cunyat Francesc , Ruiz Lidia , Marfil Silvia , Puig Teresa , Bofill Margarita , Blanco Julià , Clotet Bonaventura , Cabrera Cecilia 
Published: May 2010

Background The pathways of resistance to atazanavir (ATV) and amprenavir (APV) converge at position 50 of HIV protease. The determinants of cross-resistance were analysed during in vitro sequential or concomitant combination pressure with both drugs. Methods Recombinant viruses containing in vitro and in vivo selected I50L and I50V proteases were constructed and cultured in increasing concentrations of APV or ATV, respectively. In addition, in vitro resistance to ATV plus APV was performed. All the resistant viruses obtained were genotyped and phenotyped. Results ATV or APV alone selected I50L- or I50V-containing variants. Subsequent addition of ATV to I50V-containing recombinant viruses led to the reversion of this change and the later selection of I50L. By contrast, addition of APV to I50L-containing recombinant viruses was not associated with reversion. The combined pressure with ATV plus APV selected several changes but not at position 50. Phenotypically, both sequential and concomitant ATV–APV pressure yielded viruses resistant to all the drugs tested, although the emergence of I50L by ATV pressure on APV-resistant variants was associated with a reduced resistance to APV and darunavir. Conclusions All drug combinations led to APV plus ATV cross-resistance. The different pathways select for isoleucine or leucine at position 50, whereas the I50V mutation was excluded. Sequential pressure with ATV might have an advantage in terms of modulating the sensitivity of HIV to other protease inhibitors.
Clearing the Air: A Policy Analysis of the Ethanol Excise Tax Credit
Authors: Cato Greg 
Published: May 2010

Established in 1978, the ethanol excise tax credit has been a resounding success in helping establish a vibrant corn ethanol market, with almost 11 billion gallons produced in 2009. However, the original goals of the credit—energy security and oil independence—have not been significantly aided and, by at least some measures, have actually been hindered by the subsidy. Secondary environmental goals, such as avoidance of carbon emissions from motor fuels, show limited success. Ex post cost-benefit analyses of the subsidy have shown that it has negative to zero cost-benefit ratios and that socially optimal levels are well below current tax credit rates. The credit had a high dollar cost of $4.8 billion in 2009, and has also increased corn prices. Finally, development of a host of alternatives, such as cellulosic ethanol, have been retarded by the creation of hegemonic constituencies dependent on the credit.
Density‐driven exchange between the basins of Lake Lucerne (Switzerland) traced with the 3H‐3He method
Authors: Aeschbach‐Hertig W. , Kipfer R. , Hofer M. , Imboden D. M. , Baur H. 
Published: May 2010

Lake Lucerne is divided by sills into four major and two minor basins. During winter, differential vertical mixing due to non‐uniform wind exposure and different total dissolved solid concentrations in the main tributaries of the lake cause considerable interbasin density gradients. These gradients induce density‐driven currents across the sills that contribute significantly to the deep water exchange in the basins and gradually reduce the density gradients during summer.Over a period of 2 yr (1990–1992), the spatial and temporal evolution of water density and water age (measured by the 3H‐3He method) was investigated. Variation in water age between the different basins and the occasional occurrence of age inversions (older water overlying younger one) can be explained in terms of the observed density distribution and the exchange flows the density gradients cause. Water age provides an integral measure of the magnitude of deep‐water renewal, which in some basins can be roughly separated into contributions from density‐driven currents and wind‐induced vertical mixing.By correlating water age with dissolved helium and oxygen concentrations, radiogenic helium fluxes and average oxygen depletion rates were determined for the main basins of the lake. The helium flux was between 1 and 2 × 1010 atoms m−2 s−1, indicating dynamic equilibrium with helium production in the underlying crust. Oxygen depletion rates per unit sediment area were roughly equal in all basins (between 220 and 290 g m−2 yr−1), whereas volumetric depletion rates varied from 1.8 g m−3 yr−1 in the deepest basin to 10 g m−3 yr−1 in the shallowest.
Approximation of the size distribution of marine particles by a sum of log‐normal functions
Authors: Jonasz Miroslaw , Fournier Georges 
Published: May 2010

A simple algorithm is presented that decomposes the size distribution of marine particles into a sum of log‐normal components of the 0th order. The algorithm was applied to 412 particle‐size distributions in a particle‐diameter range of ∼0.5–200 µm measured by different researchers in various water bodies. A size distribution from this population may have from 1 to 6 log‐normal components. The variability of the number of components reflects the variability in the shape of the size distribution and variations in the size range in which the data are available. The full‐width‐at‐half‐maximum of a component is approximately proportional to the peak diameter of the component. The maximum value of a component is approximately proportional to the inverse of the square of the peak diameter.Two standard components of the marine particle‐size distribution were identified. The peak diameter (Dpeak), width parameter (σ), and maximum value (FDmax), of the first component are, respectively, 0.66 µm, 0.673, and 1.34 × 104 µm−1 cm−3. These parameters for the second component are 10.5 µm, 0.366, and 3.3 µm−1 cm−3.
Measuring the sensitivity of southern Wisconsin lake ice to climate variations and lake depth using a numerical model
Authors: Vavrus Stephen J. , Wynne Randolph H. , Foley Jonathan A. 
Published: May 2010

The sensitivity of lake ice phenology to climatic variations is tested using a numerical lake‐ice model (LIMNOS). The model simulates the evolution of ice and snow cover by time‐integrating equations of vertical heat conduction through ice and snow. The required input variables are mean lake depth, air temperature and moisture, wind speed, solar radiation, snowfall, and cloudiness.The model simulates the ice‐on and ice‐off dates of three southern Wisconsin lakes to within 1 week of their historical averages, despite large differences in mean depth. Using hourly meteorological data from 1961–1990 as inputs, LIMNOS simulates the annual ice‐on and ice‐off dates of Lake Mendota with a median absolute error of only 2 d and 4 d, respectively.The atmospheric variables are altered to determine the sensitivity of Lake Mendota ice phenology to climate change. The simulated ice‐off date shows stronger sensitivity than the ice‐on date to air temperature changes, and the sensitivity of both dates is greater for climatic warmings than coolings. Increased snowfall causes a monotonic delay in the breakup date, whereas decreased snowfall nonlinearly hastens ice decay.
Ultraviolet radiation in North American lakes: Attenuation estimates from DOC measurements and implications for plankton communities
Authors: Williamson Craig E. , Stemberger Richard S. , Morris Donald P. , Frost Thomas M. , Paulsen Steven G. 
Published: May 2010

Climate warming in North America is likely to be accompanied by changes in other environmental stresses such as UV‐B radiation. We apply an empirical model to available DOC (dissolved organic C) data to estimate the depths to which 1% of surface UV‐B and UV‐A radiation penetrate for several major regions of North America. UV attenuation depths are also estimated from DOC data collected from treatment and reference basins during the experimental acidification of Little Rock Lake, Wisconsin.In some regions of North America 25% of the lakes have 1% attenuation depths for UV‐B radiation on the order of 4 m or more (western and northwestern U.S., Newfoundland). In other regions, 75% of the lakes have 1% attenuation depths for UV‐B shallower than 0.5 m (Florida, upper midwestern U.S., northwestern Ontario, Quebec, and Nova Scotia). Attenuation depths for UV‐A radiation are ∼2.5 times as deep as those for UV‐B. Experimental acidification approximately doubled the estimated 1% attenuation depths for UV radiation in Little Rock Lake.The strong dependence of 1% attenuation depth on DOC below the 1–2 mg liter‒1 DOC range suggests that UV attenuation in low DOC lakes is highly sensitive to even very small changes in DOC. We conclude that changes in climate, lake hydrology, acid deposition, and other environmental factors that alter DOC concentrations in lakes may be more important than stratospheric ozone depletion in controlling future UV environments in lakes.
Dynamic response of deep‐sea sediments to seasonal variations: A model
Authors: Soetaer Karline , Herman Peter M. J. , Middelburg Jack J. 
Published: May 2010

We present a dynamic, numerical model of early diagenetic processes that can be used to examine the response of different organic carbon mineralization pathways, concentration vs. depth profiles, and the resultant fluxes to seasonally varying carbon deposition. We show that there can be substantial temporal variability in sediment‐water fluxes as well as in the relative contribution of different organic carbon mineralization pathways and oxygen consumption processes in deep‐sea sediments. The timing and amplitude of the sediment response are most sensitive to the reactivity of the organic matter. We show that the fluxes of dissolved substances can be approximated by assuming that these constituents are at steady state with the carbon profiles.The model is used to reconcile a time series of community oxygen consumption rates, dissolved oxygen, nitrate, ammonia, and manganese profiles, and solid‐phase organic carbon profiles at a deep‐sea station in the Pacific. The organic carbon that is deposited is very reactive (7.2 yr‒1), which causes a fast response of the sediment community to seasonal pulses in carbon flux and significant temporal variation in oxygen and nutrient fluxes. The model predicts large seasonal variations in the relative importance of oxic (48–71%), denitrification (12–17%), and anoxic (16–37%) pathways. There is also substantial variation in the pore‐water profiles of oxygen, nitrate, ammonia, and other reduced substances over the seasonal cycle, indicating that seasonal variability should be taken into account when extrapolating from a single observation to yearly averaged values.
Altered cell wall morphology in nutrient‐deficient phytoplankton and its impact on grazers
Authors: Donk E. Van , LÜrling M. , Hessen D. O. , Lokhorst G. M. 
Published: May 2010

Grazing experiments were performed with the zooplankters Daphnia pulex and Daphnia magna feeding on nitrogen‐ and phosphorus‐limited cells of two green algae (Chtamydomonas reinhardtii and Selenastrum capricornutum). To analyze the role of the cell wall structure in digestibility of the algae by Daphnia, the same experiments were carried out with both wild‐type C. reinhardtii and a cell wall‐deficient mutant.The nonlimited algae were efficiently assimilated, whereas P‐ and N‐limited algal cells were not. Especially P‐limited cells passed mostly intact and viable through the gut and were thus spared from heavy grazing pressure. In life‐history experiments, D. pulex grazing on nonlimited algae reached the largest body size, whereas animals fed N‐ or P‐limited algae exhibited reduced growth. Cells of the wall‐deficient mutant of Chlamydomonas, grown under both nutrient‐limited and nonlimited conditions, were efficiently ingested and digested by Daphnia. Morphological changes in the cell wall of nutrient‐limited cells most probably reduced their digestibility. This phenomenon might be considered a defense mechanism by the algae to reduce grazing pressure when their growth rates are low.
Hydromechanical mechanisms of colony organization and cost of hefense in an encrusting bryozoan, Membranipora membranacea
Authors: Grünbaum Daniel 
Published: May 2010

In bryozoans, hydrodynamic interactions among colony members can substantially affect filtering rates and access to food‐rich water for zooids within a colony and for the colony as a whole. Hydrodynamic theory suggests that highly integrated (area‐filling) colony architectures lead to strong interference between neighboring zooids, whereas less integrated architectures do not. The highly integrated bryozoan Membranipora membranacea displays two morphological specializations that modify hydrodynamic interactions: internal excurrent zones (chimneys) and inducible defensive spines. In this study, possible hydrodynamic mechanisms underlying the cost of inducible defense and chimney organization were tested experimentally by culturing spined and unspined colonies under controlled flow conditions.Spines reduced colony growth rate when growth was limited by clearance rates, but not when transport of particles from upstream limited growth. This supports the hypothesis that the cost of inducible defense is primarily a reduction in clearance rate (i.e. spines cause hydrodynamic interference with feeding currents) rather than metabolic investment in spine construction. Chimneys were more closely spaced in spined than unspined colonies, consistent with a mechanism for organizing chimney formation based on responses by zooids to local hydromechanical cues rather than a rigid, colony‐level control of zooid growth form (astogeny). Direct manipulation of hydrodynamic cues resulted in substantial changes in chimney morphology, again supporting the hydromechanical organization mechanism. More generally, these experimental results support the theoretical assessment that the highly integrated architecture is hydrodynamically unfavorable. The success of Membranipora in some habitats suggests that its architecture confers compensating advantages, such as improved ability to compete for space. This tradeoff in growth habit may explain shifts in relative prevalence of bryozoan architectures with depth and across other environmental gradients.