bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influences of local feedbacks on land–air exchanges of energy and carbon
Authors: Raupach M. R. 
Published: October 2003

AbstractLand–air exchanges of energy and matter are modulated by several feedback processes at both small and large space and time scales, with implications for the linked carbon, water and energy cycles. This paper studies the influences of four local feedbacks, occurring at single‐patch spatial scales and subdiurnal temporal scales, on the surface energy balance (SEB) and land–air carbon fluxes. The feedbacks are: (i) radiative feedback, the modulation of available energy through the effect of surface temperature, Ts, on outgoing longwave radiation; (ii) physiological feedback, the interaction between vegetation physiology and the SEB through Ts; (iii) aerodynamic feedback, the modulation of turbulent heat and moisture transfer by atmospheric stability; and (iv) Convective Boundary Layer (CBL) feedback, the coupling between the daytime evolution of the SEB and CBL through saturation deficit.It is found that radiative feedback is significant only over very smooth surfaces. Physiological feedback is positive with respect to Ts at moderate to high temperatures, pushing stomata towards complete closure and the SEB towards very low evaporation rates. The SEB is quite sensitive to whether or not such closure occurs. Aerodynamic feedback, on the other hand, is negative with respect to Ts at these temperatures, reducing Ts and attenuating the tendency for heat‐induced stomatal closure. CBL feedback alone does not dampen the sensitivity of the SEB to physiological feedback and stomatal closure. However, when aerodynamic feedback is included, this sensitivity is greatly reduced.
Interactions between the atmosphere and terrestrial ecosystems: influence on weather and climate
Authors: Pielke Roger A. , Sr . , Avissar RonI. , Raupach Michael , Dolman A. Johannes , Zeng Xubin , Denning A. Scott 
Published: October 2003

AbstractThis paper overviews the short‐term (biophysical) and long‐term (out to around 100 year timescales; biogeochemical and biogeographical) influences of the land surface on weather and climate. From our review of the literature, the evidence is convincing that terrestrial ecosystem dynamics on these timescales significantly influence atmospheric processes. In studies of past and possible future climate change, terrestrial ecosystem dynamics are as important as changes in atmospheric dynamics and composition, ocean circulation, ice sheet extent, and orbit perturbations.
Variations of ecosystem gas exchange in the rain forest mesocosm at Biosphere 2 in response to elevated CO2
Authors: Rosenthal YaiR. 
Published: October 2003

AbstractThe effects of elevated CO2 on tropical ecosystems were studied in the artificial rain forest mesocosm at Biosphere 2, a large‐scale and ecologically diverse experimental facility located in Oracle, Arizona. The ecosystem responses were assessed by comparing the whole‐system net gas exchange (NEE) upon changing CO2 levels from 900 to 450 ppmV. The day‐NEE was significantly higher in the elevated CO2 treatment. In both experiments, the NEE rates were similar to values observed in natural analogue systems. Variations in night‐NEE, reflecting both soil CO2 efflux and plants respiration, covaried with temperature but showed no clear correlation with atmospheric CO2 levels. After correcting for changes in CO2 efflux we show that the rain forest net photosynthesis increased in response to increasing atmospheric CO2. The photosynthetic enhancement was expressed in higher quantum yields, maximum assimilation rates and radiation use efficiency. The results suggest that photosynthesis in large tropical trees is CO2 sensitive, at least following short exposures of days to weeks. Taken at face value, the data suggest that as a result of anthropogenic emissions of CO2, tropical rain forests may shift out of steady state, and become a carbon sink at least for short periods. However, a better understanding of the unique conditions and phenomena in Biosphere 2 is necessary before these results are broadly useful.
Evidence that local land use practices influence regional climate, vegetation, and stream flow patterns in adjacent natural areas
Authors: Stohlgren Thomas J. , Chase Thomas N. , Pielke Roger A. , Sr . , Kittel Timothy G. F. , Baron JilL. S. 
Published: October 2003

AbstractWe present evidence that land use practices in the plains of Colorado influence regional climate and vegetation in adjacent natural areas in the Rocky Mountains in predictable ways. Mesoscale climate model simulations using the Colorado State University Regional Atmospheric Modelling System (RAMS) projected that modifications to natural vegetation in the plains, primarily due to agriculture and urbanization, could produce lower summer temperatures in the mountains. We corroborate the RAMS simulations with three independent sets of data: (i) climate records from 16 weather stations, which showed significant trends of decreasing July temperatures in recent decades; (ii) the distribution of seedlings of five dominant conifer species in Rocky Mountain National Park, Colorado, which suggested that cooler, wetter conditions occurred over roughly the same time period; and (iii) increased stream flow, normalized for changes in precipitation, during the summer months in four river basins, which also indicates cooler summer temperatures and lower transpiration at landscape scales. Combined, the mesoscale atmospheric/land‐surface model, short‐term trends in regional temperatures, forest distribution changes, and hydrology data indicate that the effects of land use practices on regional climate may overshadow larger‐scale temperature changes commonly associated with observed increases in CO2 and other greenhouse gases.
Terrestrial models and global change: challenges for the future
Authors: Hurtt George C. , Moorcroft PauL. R. , And Stephen W. Pacala , Levin Simon A. 
Published: October 2003

AbstractA wide variety of models have illustrated the potential importance of terrestrial biological feedbacks on climate and climate change; yet our ability to make precise predictions is severely limited, due to a high degree of uncertainty. In this paper, after briefly reviewing current models, we present challenges for new terrestrial models and introduce a simple mechanistic approach that may complement existing approaches.
Investigations on Heterobasidion annosum s.lat. in central and eastern Asia with the aid of mating tests and DNA fingerprinting
Authors: Dai Y. ‐C. , Vainio E. J. , Hantula J. , Niemelä T. , Korhonen K. 
Published: October 2003

SummaryTo investigate the taxonomy of Heterobasidion in Eurasia, 49 specimens belonging to H. annosum sensu lato from Asia were identified with the aid of mating tests. Most of the specimens originated from north‐eastern and south‐western China and from the Altai region in southern Siberia, but a few isolates from Kirghizia, Japan and India were also tested. In addition to mating tests, the material from China was investigated with DNA fingerprinting. Heterobasidion annosum sensu stricto was identified only from the Altai region. Homokaryotic isolates from other specimens, except the Indian ones, were sexually compatible with H. parviporum, but they also showed a high degree of compatibility with H. abietinum and with the North American S group. The isolates from SW China (eastern Himalayas) mated with about equal frequency with the European strains of H. parviporum and H. abietinum. However, the DNA fingerprinting showed that these isolates were more closely related to H. parviporum, and hence they were tentatively included in this species. The North American S group was more distant from these Eurasian taxa. Four old isolates from India mated only weakly with the members of the H. annosum s.lat. According to the species concept presented, the distribution of H. parviporum extends from western Europe through southern Siberia to northern China, Japan and the eastern Himalayas. H. annosum s.str. is so far identified only from the Altai region outside Europe, and H. abietinum only from Europe.
Down‐regulation of inducible nitric oxide synthase (iNOS) in rat with congenital hydronephrosis
Authors: ZHOU YUN , TAKAHASHI GO , YONAMINE KYOKO 
Published: October 2003

AbstractBackground: Most of our knowledge concerning obstructive uropathy has been derived mainly from surgically manipulated animal models, and the pathogenesis of congenital obstructive hydronephrosis is not fully elucidated. Nitric oxide (NO) acts as an important biological modulator with diverse physiological functions, which can be either toxic or protective depending on the situation. NO is synthesized from l‐arginine by nitric oxide synthase, and in the kidney iNOS is expressed spontaneously. The aim of our study is to investigate the expression of iNOS protein and its relationship with tubulointerstitial fibrosis and tubular cell apoptosis in congenital hydronephrosis.Methods: We conducted histological studies on 18 kidneys of six‐week‐old‐rats from an inbred colony of congenital hydronephrosis with reference to the histological grading of the affected kidney, tubulointerstitial fibrosis, renal tubular atrophy, and tubular cell apoptosis. Renal transforming growth factor‐β1 (TGF‐β1) level was determined by a sandwich ELISA assay and the expression of iNOS was analyzed by western blotting.Results: Most of the hydronephrotic kidneys were markedly enlarged with dilatation of the collecting system, parenchymal thinning, tubular atrophy, interstitial infiltration and fibrosis. Renal TGF‐β1 level was higher in hydronephrotic kidneys than normal control kidneys (364.81 ± 52.60 vs. 221.19 ± 22.53 pg/mg protein, P < 0.05). Tubular apoptotic score in hydronephrotic kidneys was also significantly higher than in the normal control kidneys (1.97 ± 0.42 vs. 0.14 ± 0.02/HPF, P < 0.01). The expression of iNOS protein was lower in the affected kidneys compared with the normal control kidneys (8.79 ± 0.78 vs. 14.00 ± 0.83 arbitrary unit, P < 0.01). There was a negative correlation between iNOS expression and histological grading in congenital hydronephrosis. The iNOS expression also correlated negatively with renal interstitial fibrosis, TGF‐β1 level and tubular cell apoptosis.Conclusion: Our study confirmed the down‐regulation of iNOS expression in affected kidneys from rats with congenital hydronephrosis, in which the cytoprotective effect of NO may be lost or weakened.
Acid neutralization and bile acid binding capacity of hydrotalcite compared with other antacids: An in vitro study
Authors: MIEDERER S‐E , WIRTZ M , FLADUNG B 
Published: October 2003

OBJECTIVE:  Antacids are used worldwide for the treatment of acid‐related conditions such as heartburn and gastro‐esophageal reflux disease. The present study investigated the in vitro acid neutralization and bile acid binding capacities of hydrotalcite compared with other antacids that are available in Germany and China. It has been reported that hydrotalcite is effective in the treatment of bile reflux gastritis because of its binding capacity to bile acids.METHODS:  Hydrotalcite and other preparations of antacids were tested in a comparative in vitro study. The neutralization properties were determined with static and dynamic tests (preliminary antacid test, acid neutralization capacity (ANC) test, Rossett‐Rice (RR) test) and the bile acid binding test with a standardized commercial test kit (Merckotest bile acids).RESULTS:  In the static and dynamic tests hydrotalcite 500 mg and some other antacids, such as magaldrate, almasilate, algedrate Mg hydroxide, Ca/Mg carbonate and calcium carbonate, demonstrated favorable ANC reflected by rapid onset and long duration of action, and high buffering capacity. In the RR test, a hydrotalcite dose of 1000 mg was able to keep the pH level above 3 for 76.9 min. The bile acid binding capacity test yielded that hydrotalcite had the highest binding potential to taurodeoxycholic acid, a lipophilic bile acid associated with cell and mucosa toxicity.CONCLUSIONS:  Hydrotalcite has a rapid onset of action, a high buffering capacity and a long duration of action. In particular, hydrotalcite binds cytotoxic bile acids. These pharmacochemical properties make hydrotalcite a most suitable antacid.
Hepatoprotective effect of a curcumin/absinthium compound in experimental severe liver injury
Authors: MAROTTA F , SHIELD YR , BAMBA T , NAITO Y , MINELLI E , YOSHIOKA M 
Published: October 2003

OBJECTIVE:  A preliminary in vitro study with hepatocyte culture showed that concentrations as low as 10 µg/mL of PN‐M001 are able to significantly mitigate CCl4 hepatocyte damage (P < 0.05) comparable to 100 µg/mL silymarin, and 100 µg/mL proved to be more protective than either silymarin 100 µg/mL or glycyrrhizin 10 µg/mL (P < 0.05).METHODS:  Wistar rats were allocated into three groups: (A) 0.1 mL/100 g body weight (BW) mixture of CCl4 in olive oil (1 : 1 v/v) subcutaneous injection twice daily for 4 weeks; (B) as A, plus oral administration of 50 mg/kg of K‐17.22 dissolved in 5% glucose; (C) as B but with PN‐M001 given 1 week after the first injection of CCl4. Rats were killed at the end of the study and blood and liver samples were obtained.RESULTS:  When compared with a control, group A showed a significant decrease of glutathione (GSH;>45%, P < 0.001) and oxidized GSH (GSSG; P < 0.01) liver content, a lower liver wet weight (P < 0.01) together with an increase of both transaminases (>15‐fold, P < 0.001) whereas groups B and C both showed only a mild increase in transaminases (<4‐fold, P < 0.05). Group A showed a significant decrease of Y‐protein fraction and of GST activity, as tested by both substrates (P < 0.01 vs control). However, both these parameters were reverted to normal by PN‐M001 (P < 0.05 vs A).CONCLUSIONS:  These preliminary data suggest that PN‐M001 exerts a highly protective and prolonged effect (either preventive or therapeutic) on GSH depletion in CCl4‐induced liver injury, which suggests its potential use in the clinical setting.
Mast cells and neuropeptidergic terminals: Experimental studies of the mechanism of visceral hypersensitivity in irritable bowel syndrome
Authors: LI Zhao Shen , DONG Wen Zhu , ZOU Duo Wu , ZOU Xiao Ping , XU Guo Ming , ZHU Ai Yong , YIN Ning , GONG Yan Fang , SUN Zhen Xing , XU Can , MAN Xiao Hua 
Published: October 2003

OBJECTIVE:  The failure of dysmotility to explain the symptoms of pain in irritable bowel syndrome (IBS) led to studies on visceral hypersensitivity. Mucosal mast cells (MC) may be one factor influencing the response of visceral afferents to mechanical and chemical stimuli because they are found in close proximity to gastrointestinal mucosal sensory nerve terminals containing neuropeptides and a bi‐directional pathway linking the central nervous system, gut and MC has been demonstrated.METHODS:  The present study investigated the extent of MC and the neuropeptides, substance P (SP) and vasoactive intestinal peptide (VIP), in the intestinal mucosa of patients with IBS, as well as the location of the MC. The MC and neuropeptidergic terminals were stained histochemically and immunohistochemically, respectively, neuropeptide concentrations were measured by radioimmunoassay (RIA), and the results were investigated qualitatively and quantitatively by color image analyzer. The structural relation between the MC and neuropeptide terminals was studied by ultramicroscopy using in situ embedding technique.RESULTS:  In IBS, the number of MC in the terminal ileum, the ileocecal junction, and the ascending colon was significantly increased (P < 0.01), and the MC had great variations in their extent and size. Significantly increased concentrations of VIP and SP were found in the colon of IBS patients compared with controls. A correlation between mucosal MC and the SP(VIP)‐ergic terminals was found, and the MC were close to these terminals in the lamina propria, which demonstrated SP (VIP)‐ergic terminals.CONCLUSIONS:  Mast cells and the neuropeptides of intestinal mucosa may play a central role in gut hypersensitivity, resulting in both the motor response and visceral perceptions that occur with IBS.
The prevalence of reduced zidovudine susceptibility in zidovudine‐naive, antiretroviral‐experienced HIV‐1‐infected patients
Authors: Gilleece Y , Torti C , Mandalia S , Gazzard BG , Pillay D , Pozniak AL 
Published: October 2003

ObjectivesThere is increasingin vitroandin vivoevidence that reduced zidovudine (ZDV) susceptibility is generated by the selective pressure conferred by other nucleoside reverse transcriptase inhibitors (NRTIs). However, the degree to which this occurs in clinical practice remains unclear. We assessed phenotypic and genotypic resistance in ZDV‐naive patients with virological failure on stavudine (d4T)‐containing regimens, with particular reference to potential cross‐resistance between d4T and ZDV.MethodsPatients were identified from a clinical database. Treatment history was confirmed by case note evaluation and discussion with patients. Genotypic and phenotypic analyses were undertaken by Virco (Virco BVBA, Mechelen, Belgium).ResultsSixty‐seven drug‐experienced, ZDV‐naive patients who underwent a resistance test while failing a d4T‐containing regimen were identified. Of these patients, 23% had received three or more NRTIs and 42% at least one non‐nucleoside reverse transcriptase (RT) inhibitor; 22% had viruses with reduced d4T susceptibility (>1.8‐fold resistance), and 25% had viruses with reduced ZDV susceptibility (>4‐fold). The most frequently observed RT mutations were identified. A significant correlation was found between susceptibility to d4T and susceptibility to ZDV (r=0.36;P=0.003), and also between virtual resistance to d4T and that to ZDV (r=0.38;P=0.002).ConclusionsA significant minority of d4T‐treated, ZDV‐naive patients were found to have viruses with reduced ZDV susceptibility, with a variable association with classical ZDV resistance mutations. These data suggest that cross‐resistance between d4T and ZDV may involve novel constellations of mutations. Correlations between d4T and ZDV susceptibilities and resistances further support cross‐resistance between NRTIs.
Overcoming subjectivity in assessing facial lipoatrophy: is there a role for three‐dimensional laser scans?
Authors: Benn P , Ruff C , Cartledge J , Sauret V , Copas A , Linney A , Williams IG , Smith C , Edwards SG 
Published: October 2003

BackgroundPrevalence and incidence rates of lipodystrophy vary widely and frequently rely upon self‐ and/or clinician reports. Currently no validated assessment tool for facial lipoatrophy is available.Aims and objectivesTo illustrate that assessment of the severity of facial lipoatrophy by patients and clinicians is subjective. To evaluate the reproducibility of facial three‐dimensional surface laser scans.MethodsTwenty‐three HIV‐positive men were recruited from an inner London HIV outpatient clinic in September 2001. CD4 count, viral load, antiretroviral history and body mass index were recorded. Patients and clinicians independently assessed the severity of facial lipoatrophy on a four‐point scale and the level agreement was measured. Seventeen of the 23 patients (73.9%) underwent two scans 1 week apart, which were then superimposed. The volume difference (mm3) and mean difference (mm) between the scans for five regions of the face were measured and compared with the self‐reported grade of facial lipoatrophy.ResultsFor each pair of clinicians (P=0.03, 0.005 and 0.0002, respectively), and for one patient–clinician pair (P=0.004), there was a significant systematic difference between the two sets of gradings of facial lipoatrophy. The level of disagreement was generally higher for patients reporting facial lipoatrophy (n=17) compared to those not reporting it (n=6). The mean volume difference and mean difference between any region were within 200 mm3 and 0.25 mm, respectively. Reproducibility was unaffected by the self‐reported grade of facial lipoatrophy.ConclusionsAssessment of the severity of facial lipoatrophy by patients and clinicians is subjective. Three‐dimensional facial laser scans are reproducible and may provide an objective tool for monitoring changes in facial lipoatrophy.
Recurrence of Pneumocystis carinii pneumonia in an HIV‐infected patient: apparent selective immune reconstitution after initiation of antiretroviral therapy
Authors: Crothers K , Huang L 
Published: October 2003

SummaryAlthough several studies have reported that it is safe to discontinue secondary Pneumocystis carinii pneumonia (PCP) prophylaxis in patients infected with HIV who experience a sustained immune response as a result of antiretroviral therapy, we describe a patient who developed recurrent PCP <3 months after discontinuing trimethoprim‐sulfamethoxazole prophylaxis. He developed disease despite a sustained CD4 T‐cell count above 200 cells/μL for more than 3 years while on antiretroviral therapy, as well as an apparent immune reconstitution against disseminated Mycobacterium avium complex (MAC) and Histoplasma capsulatum, for which he also discontinued therapy but without adverse effects. Thus, although increasing evidence continues to indicate that HIV‐infected patients receiving combinations of antiretroviral therapies may regain specific immunity against opportunistic infections, our patient's experience suggests that this immune recovery may be selective and incomplete.
Interactions Between Extracellular Stimuli and Excitation Waves in an Atrial Reentrant Loop
Authors: JOHNSON CHAD R. , BARR ROGER C. 
Published: October 2003

Introduction: The interactions between extracellular stimuli and excitation waves propagating in a reentrant loop are a complex function of stimulus parameters, structural properties, membrane state, and timing. Here the goal was a comprehensive understanding of the mechanisms and frequencies of the major interactions between the advancing excitation wave and a single extracellular stimulus, separated from issues of anatomic or geometric complexity. Methods and Results: A modernized computer model of a thin ring of uniform tissue that included a pair of extracellular stimulus electrodes (anode/cathode) was used to model one‐dimensional cardiac reentry. Questions and results included the following: (1) What are the major interactions between a stimulus and the reentrant propagation wave, and are they induced near the cathode or near the anode; and, for each interaction, what are the initiating amplitude range and timing interval? At the cathode, the well‐known mechanism of retrograde excitation terminated reentry; changes in timing or amplitude produced double‐wave reentry or phase reset. At the anode, termination occurred at different cells depending on stimulus amplitude. (2) Relatively how often did termination occur at the anode? For most stimulus amplitudes, termination occurred more often at the anode than at the cathode, although not always at the same cell. (3) With random timing, what is the probability of terminating reentry? Stimulation for 5 msec terminated reentry with a probability from 0% to approximately 10%, as a function of increasing stimulus amplitude. Conclusion: A single extracellular stimulus can initiate major changes in reentrant excitation via multiple mechanisms, even in a simple geometry. Termination of reentry, phase shifts, or double‐wave reentry each occurs over well‐defined ranges of stimulus amplitude and timing. (J Cardiovasc Electrophysiol, Vol. 14, pp. ***‐***, October 2003)