bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional and hemispheric impacts of anthropogenic and biomass burning emissions on summertime CO and O3 in the North Atlantic lower free troposphere
Authors: Honrath R. E. , Owen R. C. , Val Martín M. , Reid J. S. , Lapina K. , Fialho P. , Dziobak M. P. , Kleissl J. , Westphal D. L.
Published: December 2004

We report summertime measurements of CO and O3 obtained during 2001–2003 at the PICO‐NARE mountaintop station in the Azores. Frequent events of elevated CO mixing ratios were observed. On the basis of backward trajectories arriving in the free troposphere and global simulations of biomass burning plumes, we attribute nearly all these events to North American pollution outflow and long‐range transport of biomass burning emissions. There was a high degree of interannual variability in CO levels: median [CO] ranged from 65 ppbv in 2001 to 104 ppbv in 2003. The highest concentrations were associated with transport of Siberian fire emissions during summer 2003, when Siberian fire activity was unusually high. Ozone mixing ratios also increased (by up to ∼30 ppbv) during the fire events. These findings demonstrate the significant hemispheric scale impact that biomass burning events have on background CO and O3 levels. O3 enhancements of similar magnitude were also observed in North American pollution outflow. O3 and CO were correlated during North American outflow events, with a slope averaging 1.0 (d[O3]/d[CO], ppbv/ppbv) when no fire impact was present. This slope is more than 80% larger than early 1990s observations made in the eastern United States and nearshore outflow region, even after accounting for declining U.S. CO emissions and for CO loss during transport to the Azores, and is not consistent with simple dilution of U.S. outflow with marine background air. We conclude that a significantly larger amount of O3 production occurred in the air sampled during this study, and we suggest several potential reasons for this, each of which could imply potentially significant shortcomings in current estimates of the hemispheric impact of North American emissions on tropospheric ozone and should be evaluated in future studies.
Method of birth alters interferon‐gamma and interleukin‐12 production by cord blood mononuclear cells
Authors: Brown Mark A. , Rad Parmis Y. , Halonen Marilyn J.
Published: December 2004

Many uncertainties exist regarding the capability of cord blood mononuclear cells (CBMC) to produce cytokines. A number of conflicting reports led us to examine the effects of method of birth on CBMC production of interferon‐gamma (IFN‐γ), interleukin‐4 (IL‐4) and interleukin‐12 (IL‐12). While constitutive production of IL‐4 was found in both vaginally and cesarean‐delivered infants, constitutive IFN‐γ or IL‐12 production was found in neither. CBMC from vaginally delivered infants responded to stimulation with concanavalin A/phorbol 12‐myristate 13‐acetate (Con A/PMA), phytohemagglutinin (PHA), and lipopolysaccharide (LPS) with significantly higher levels of IFN‐γ than CBMC from unlabored cesarean section (CS) infants. Production of IL‐12 was increased in the vaginally delivered group in response to LPS and PHA but not to ConA/PMA. In contrast, mode of delivery was not associated with differences in IL‐4 production. These results indicate that mode of delivery significantly alters the capability of CBMC to produce some cytokines and therefore should be taken into account in interpreting fetal/neonatal mononuclear cell function studies.
Increased serum IL‐10/IL‐12 ratio in wheezing infants
Authors: Koopman Laurens P. , Savelkoul Huub , Van Benten Inesz J. , Gerritsen Jorrit , Brunekreef Bert , J. Neijens Herman
Published: December 2004

To investigate the association between various serum markers and atopic symptoms in the first year of life, and to evaluate the prognostic value of these markers for the development of wheezing and skin rash in the second year of life. Data of 86 children on the development of wheezing and skin rash in the first 2 years of life were collected prospectively, making use of parental completed questionnaires, weekly symptom cards, structured interview and physical examination. Serum markers (IL‐10, IL‐12, IL‐13, eotaxin, sE‐selectin, sICAM‐1, sIL‐2R) and total and specific IgE were determined at age 1. Children who developed wheezing in the first year of life had lower serum levels of IL‐12 than children without symptoms (median 40.3 pg/ml vs. 49.0 pg/ml, p = 0.01) and a higher serum IL‐10/IL‐12 ratio (0.41 vs. 0.31, p = 0.001) at age 1. The IL‐10/IL‐12 ratio increased with an increasing number of wheezing episodes. Levels of sE‐selectin in children with wheezing and in children with itchy skin rash in the first year of life were higher than in symptom free children (6.1 ng/ml and 5.9 ng/ml vs. 4.9 ng/ml, p = 0.01 and p = 0.03, respectively). Children who developed wheezing in the second year of life already had increased sICAM‐1 levels at age 1. Children who developed wheezing in the first year of life showed a serum cytokine response that is skewed towards a T‐helper 2 profile, with lower IL‐12 levels and an increased IL‐10/IL‐12 ratio. Children who developed wheezing in the second year of life had elevated sICAM‐1 levels at age 1. Follow‐up of the children is needed to evaluate the prognostic value of various serum markers for the development of allergic disease in later childhood.
Hypersaline nasal irrigation in children with symptomatic seasonal allergic rhinitis: A randomized study
Authors: Garavello Werner , Romagnoli Marco , Sordo Lorenza , Gaini Renato Maria , Berardino Cristina Di , Angrisano Alfonso
Published: December 2004

Recent evidence suggests that nasal irrigation with hypertonic saline may be useful as an adjunctive treatment modality in the management of many sinonasal diseases. However, no previous studies have investigated the efficacy of this regimen in the prevention of seasonal allergic rhinitis‐related symptoms in the pediatric patient. Twenty children with seasonal allergic rhinitis to Parietaria were enrolled in the study. Ten children were randomized to receive three‐times daily nasal irrigation with hypertonic saline for the entire pollen season, which had lasted 6 weeks. Ten patients were allocated to receive no nasal irrigation and were used as controls. A mean daily rhinitis score based on the presence of nasal itching, rhinorrea, nasal obstruction and sneezing was calculated for each week of the pollen season. Moreover, patients were allowed to use oral antihistamines when required and the mean number of drug assumption per week was also calculated. In patients allocated to nasal irrigation, the mean daily rhinitis score was reduced during 5 weeks of the study period. This reduction was statistically significantly different in the 3th, 4th and 5th week of therapy. Moreover, a decreased consumption of oral antihistamines was observed in these patients. This effect became evident after the second week of treatment and resulted in statistically significant differences during the 3th, 4th and 6th week. This study supports the use of nasal irrigation with hypertonic saline in the pediatric patient with seasonal allergic rhinitis during the pollen season. This treatment was tolerable, inexpensive and effective.
Hay fever and predictive value of prick test and specific IgE antibodies: A prospective study in children
Authors: Schäfer Torsten , Hoelscher Bernd , Adam Horst , Ring Johannes , Wichmann H.‐Erich , Heinrich Joachim
Published: December 2004

Little is known from population‐based studies in children about the diagnostic values of allergen‐specific IgE antibodies (RAST) and skin prick test (SPT) with respect to hay fever. We aimed to determine and compare the diagnostic values of SPT and RAST to aeroallergens with respect to the incidence of hay fever cases in schoolchildren at different cut‐off points. A prospective cohort study was performed on 1100 school children (5–7 and 8–10 years). Information on a doctor's diagnosis of hay fever was obtained by questionnaire and allergic sensitization to grass and birch pollen, cat, and Dermatophagoides pteronyssinus were measured using SPT and RAST between September 1992 and July 1993. Thirty‐eight children give a history of hay fever (3.5%) in 1992/93 and additionally 37 cases occurred until 1996. Allergic sensitization was present in 17.9% (SPT), 30.2% (RAST) and more frequent in children with a history of hay fever (SPT: OR 11.7, 5.5–24.7; RAST: OR 10.6, 4.3–26.4). This difference was most pronounced for sensitization to pollen allergens. The sensitivity, specificity, positive and negative predictive values (PPV, NPV) for SPT and RAST were 65.6, 83.7, 11.9, 98.6 and 79.3, 71.6, 9.3, 99.0, respectively, with differences for specificity being significant (p < 0.001). Whereas NPV were equally high for SPT (99.2) and RAST (99.3), the incidence of hay fever cases were predicted rather poorly though somewhat better by SPT than by RAST (PPV 16.7 vs. 9.8; p < 0.001) initially. With increasing cut‐off point for RAST reactivity, the PPV increased and reached 25.0 at 17.5 kU/l, whereas the NPV decreased to 97.9, which was lower than that of SPT reactivity (p < 0.01). At the cut‐off point of 1.5 kU/l almost identical predictive values for SPT and RAST were obtained. SPT and RAST perform better in the negative than positive prediction of hay fever cases in epidemiological studies. Differences in the predictive capabilities depend on the chosen cut‐off point for RAST reactivity.
Eosinophil granule proteins in the assessment of airway inflammation in pediatric bronchial asthma
Authors: Wolthers O. D.
Published: December 2004

Eosinophil granule proteins such as eosinophil cationic protein (ECP), eosinophil peroxidase (EPO) and eosinophil protein X (EPX) in serum and urine are indirect measures of eosinophil activity. The measures have been evaluated for prediction, diagnosis and monitoring of anti‐inflammatory treatment modalities in children with asthma. Assessments in serum and urine are highly dependent on sampling procedures and must be performed under strictly controlled conditions using standardized sampling and laboratory procedures. The measures are influenced by circadian and seasonal variations. Measurement of the eosinophil granule proteins does not improve the predictive value of a family history of atopy. Due to insufficient sensitivity and specificity, the measures are not useful in the diagnosis of asthma in children, and the clinical use of eosinophil proteins in the individual child for assessment of asthma severity has not been sufficiently validated. Serum and urine eosinophil granule proteins, however, may be useful in extending our knowledge of suppressive effects on eosinophil activity of various doses, devices and administration regimens of inhaled glucocorticoids in children. Such evaluations may be performed in randomized, double‐blind trials of well‐defined age groups and they should include measures of compliance. One important aspect to look at would be the distinction between suppressive effects on eosinophil activity and clinically important anti‐inflammatory effects. Considering the complexity of airway inflammation and the heterogeneity of childhood asthma, however, it may be too simplistic to look for a single measure of the inflammatory processes. In the future, perhaps, a combination of products of inflammatory cells may give more clinically relevant information with respect to prediction, diagnosis, monitoring and outcome of childhood asthma.
Assessment of quality of life in children with peanut allergy
Authors: Avery Natalie J. , King Rosemary M. , Knight Susan , Hourihane Jonathan O'B.
Published: December 2004

Children with a peanut allergy (PA) are faced with food and social restrictions due to the potentially life‐threatening nature of their disease, for which there is no cure or treatment. This inevitably impacts upon their quality of life (QoL). QoL of 20 children with PA and 20 children with insulin‐dependent diabetes mellitus (IDDM) was measured using two disease‐specific QoL questionnaires (higher scores correspond to a poorer QoL). One questionnaire was designed by us and the other was adapted from the Vespid Allergy QoL questionnaire. We gave subjects cameras to record how their QoL is affected over a 24‐h period. Response rates for both questionnaires were 100%. Mean ages were 9.0 and 10.4 years for PA and IDDM subjects, respectively. Children with a PA reported a poorer quality of life than children with IDDM: mean scores were 54.85 for PA subjects and 46.40 for diabetics (p = 0.004) in questionnaire 1 and 54.30 and 34.50 (p≤0.001) in questionnaire 2. PA children reported more fear of an adverse event and more anxiety about eating, especially when eating away from home. Photographs fell into seven common categories: food, management, environment, away from home, physical activities, restaurant and people. Most photographs related to food and management issues and revealed difficulties for both groups regarding food restrictions. PA subjects felt more threatened by potential hazards within their environment, felt more restricted by their PA regarding physical activities, and worried more about being away from home. However, they felt safe when carrying epinephrine kits and were positive about eating at familiar restaurants. The QoL in children with PA is more impaired than in children with IDDM. Their anxiety may be considered useful in some situations, promoting better adherence to allergen avoidance advice and rescue plans.
Relationship between group A beta‐hemolytic streptococcal tonsillopharyngitis and asthma
Authors: Del Carmen Trojavchich Maria , Crisci Carlos D. , Shafa Mehrdad , Rybicki Benjamin A.
Published: December 2004

Increasing morbidity due to asthma in children and antimicrobial resistance among human pathogens are both major public‐health concerns. Frequent use of antibiotics during childhood might be a factor underlying the rising severity and prevalence of asthma and other allergic disorders. The objective of the study was to determine if pediatric patients with asthma or allergic rhinitis have an altered rate of group A beta hemolytic streptococcal (GABHS) tonsillopharyngeal infection which might support any change in guidelines for antibiotic prescription. A prospective analysis of all patients presenting a clinical feature of GABHS pharyngitis with a sore throat in two pediatric clinics located in Detroit, MI, USA and San Antonio de Areco, Buenos Aires, Argentina. Eligible patients aged between 2 and 18 years were screened for the presence of asthma and/or allergic rhinitis and administered a test (rapid strep test) and throat culture to determine GABHS infection. At the Redford Medical Center, Detroit, 500 patients met the eligibility criteria, with 168 (33.6%) having a positive strep test. At the San Antonio de Areco's Hospital, in a rural area 100 km away from Buenos Aires, 188 patients met the eligibility criteria, with 41 (21.8%) having a positive strep test or GABHS throat cultures. In both the Detroit [odds ratio (OR) = 1.36; 95% confidence interval (CI) 0.72–2.57] and Buenos Aires clinics (OR = 0.50; 95% CI 0.23–1.07), patients with asthma or allergic rhinitis were not at an increased risk for true GABHS tonsillopharyngeal infections when compared with the general pediatric population. These results suggest that children with asthma do not differ from the normal population in their risk of developing GABHS tonsillopharyngeal infection and should not be liberally prescribed antibiotics.
Echocardiographic findings of hypertrophic cardiomyopathy in children after orthotopic liver transplantation
Authors: Chang Ruey‐Kang R. , McDiarmid Sue V. , Alejos Juan C. , Drant Stacey E. , Klitzner Thomas S.
Published: December 2004

Abstract: This study was carried out to compare echocardiographic findings of children taking tacrolimus and cyclosporin A (CsA) after orthotopic liver transplantation (OLT). Echocardiograms of 19 children were reviewed during hospitalizations after OLT, and echocardiograms were performed on 23 children who returned to the clinic for a routine follow‐up visit after OLT. Measurements were made of the left ventricle (LV) end‐diastolic dimension, and of the thickness of the LV free wall (LVFW) and the inter‐ventricular septum (IVS). From these measurements, the LV mass was calculated. LV outflow gradient was measured by using Doppler interrogation. Comparisons were made between patients on CsA and patients on tacrolimus. Children with hypertrophic cardiomyopathy (HCM) were identified. Two patients from the in‐patient tacrolimus group were found to have HCM. These two patients had asymmetric septal hypertrophy with dynamic LV outflow obstruction and were successfully treated with propranolol, with or without discontinuing tacrolimus. In the out‐patient studies, there was no difference in LVFW and IVS thickness, or LV mass index, between children on CsA and children on tacrolimus. Hence, tacrolimus is associated with the development of HCM in children. The effect of tacrolimus on HCM development may be acute and temporary. More data are needed to determine the incidence of HCM in children on tacrolimus therapy and to establish guidelines for clinicians who follow‐up these children.
Transjugular intrahepatic portosystemic shunt prior to renal transplantation in a child with autosomal‐recessive polycystic kidney disease and portal hypertension: A case report
Authors: Benador Nadine , Grimm Paul , Lavine Joel , Rosenthal Philip , Reznik Vivian , Lemire Jacques
Published: December 2004

Abstract: Autosomal‐recessive polycystic kidney disease (ARPKD) can cause renal failure and portal hypertension in children. Portal hypertension may complicate the course of renal transplantation (Tx). We report the successful outcome of a patient with end‐stage renal disease (ESRD) and portal hypertension treated with transjugular intrahepatic portosystemic shunt (TIPS), a minimally invasive endovascular technique of portosystemic shunt, prior to renal Tx.
Changes in left ventricular mass index in children and adolescents after renal transplantation
Authors: Mitsnefes Mark M. , Schwartz Steven M. , Daniels Stephen R. , Kimball Thomas R. , Khoury Philip , Strife C. Frederic
Published: December 2004

Abstract: Recent reports indicate a high prevalence of left ventricular hypertrophy (LVH) in children on dialysis and after renal transplantation (Tx), as identified by cross‐sectional analysis. However, the evolution of LVH in pediatric patients with end‐stage renal disease after renal Tx is not well established. To assess changes of left ventricular mass (LVM), we prospectively performed echocardiography in 23 children and adolescents between November 1998 and July 2000. Each patient had an echocardiographic evaluation while on dialysis (for at least 6 weeks) and a follow‐up evaluation at least 6 months after successful renal Tx (i.e. with a measured glomerular filtration rate [GFR] of at least 40 mL/min/1.73 m2). The LVM index was estimated by indexing LVM to height2.7. Sixteen patients had a cadaveric transplant and seven had a live donor transplant; the mean duration between the two studies was 1.9 ± 1.6 yr; and the mean GFR was 55.0 ± 21.4 mL/min/1.73 m2. There was no significant difference in the mean values of the LVM index while on dialysis and after renal Tx (43.9 ± 17.8 g/m2.7 and 39.3 ± 12.0 g/m2.7, respectively, p = 0.19), or in the prevalence of LVH (52% and 56%, respectively). Interval changes in the LVM index in individual subjects between the two studies were significantly associated with interval changes in indexed systolic (r = 0.42, p = 0.04) and diastolic (r = 0.42, p = 0.05) blood pressures. Interval changes in hemoglobin, blood urea nitrogen (BUN), creatinine, and duration after Tx did not correlate with changes in the LVM index. There was no significant difference in LVM index change according to the type of dialysis, donor source, and the cause of renal failure. In multivariate analysis, the baseline LVM index and changes in indexed SBP were independent predictors for LVM index change after renal Tx. We conclude that LVH persists in children and adolescents after renal Tx. Control of blood pressure might be an important factor in regression or prevention of progression of LVH in these patients.
Neurocognitive outcome in pediatric liver transplant recipients
Authors: Krull Kevin , Fuchs Carola , Yurk Helene , Boone Pamela , Alonso Estella
Published: December 2004

Abstract: Studies have shown that children with liver transplants demonstrate deficits on intellectual, academic, and language measures. However, limited information is known about the long‐term cognitive development of these children. In this study, 15 children who were at least 2 yr post‐liver transplantation (LT) were compared on cognitive measures to an equated group of 15 children with cystic fibrosis (CF). Children with CF were selected as a clinical control given similarities in disease onset and chronicity, as well as physical growth and development. Results indicated that children with LT tended to have lower verbal intelligence quotient scores and performed significantly lower than CF children on language measures, particularly on receptive language tasks. No significant differences were obtained on measures of academic achievement or visual–spatial performance. In the LT group, days in the intensive care unit, total number of days spent in the hospital during the first year following the transplant, and elevated pretransplant bilirubin levels significantly predicted the speech and language delays.
Improvement of hepatopulmonary syndrome after transjugular intrahepatic portasystemic shunting: Case report and review of literature
Authors: Paramesh Anil S. , Husain Sohail Z. , Shneider Benjamin , Guller Jeffrey , Tokat Ikbal , Gondolesi Gabriel E. , Moyer Susan , Emre Sukru
Published: December 2004

Abstract:  The hepatopulmonary syndrome has been described in as many as 5–29% of patients with liver disease. Patients with this syndrome may suffer from chronic hypoxemia, and mortality rates of liver patients with this syndrome are as high as 41%. Early diagnosis of such patients is essential. Currently, liver transplantation is the only effective therapy for such patients, and reversal of this syndrome is seen in up to 80% of patients post‐transplant. Transjugular intrahepatic portasystemic shunting (TIPS) as a therapeutic maneuver for this syndrome has been described in five patients to date with mixed results. Reduction in portal hypertension with consequent redistribution of blood flow and altered synthesis of vasodilatory chemicals have been postulated to help resolve this disease. In this report, we describe an 11‐yr‐old female with biliary atresia and hepatopulmonary syndrome. Her disease was complicated with recurrent variceal bleeding. TIPS achieved a therapeutic response of both her bleeding and respiratory complications.
Methods for isolating and characterizing ACC deaminase‐containing plant growth‐promoting rhizobacteria
Authors: Penrose Donna M. , Glick Bernard R.
Published: December 2004

One of the major mechanisms utilized by plant growth‐promoting rhizobacteria (PGPR) to facilitate plant growth and development is the lowering of ethylene levels by deamination of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) the immediate precursor of ethylene in plants. The enzyme catalysing this reaction, ACC deaminase, hydrolyses ACC to α‐ketobutyrate and ammonia. Several bacterial strains that can utilize ACC as a sole source of nitrogen have been isolated from rhizosphere soil samples. All of these strains are considered to be PGPR based on the ability to promote canola seedling root elongation under gnotobiotic conditions. The treatment of plant seeds or roots with these bacteria reduces the amount of ACC in plants, thereby lowering the concentration of ethylene. Here, a rapid procedure for the isolation of ACC deaminase‐containing bacteria, a root elongation assay for evaluating the effects of selected bacteria on root growth, and a method of assessing bacterial ACC deaminase activity are described in detail. This should allow researchers to readily isolate new PGPR strains adapted to specific environments.
Wound‐induced superoxide production and PAL activity decline with potato tuber age and wound healing ability
Authors: Kumar G. N. Mohan , Knowles N. Richard
Published: December 2004

Wound healing of potato tubers involves the concerted action of several enzymes that facilitate polymerization of phenolics into suberin at the wound site. A decline in the efficiency of healing and resistance to pathogens with advancing tuber age was associated with reduced ability of older tubers to produce superoxide radicals (FRs) in response to wounding. Autophotographs of luminol‐treated longitudinal sections of tissue from 6‐, 18‐ and 30‐month‐old tubers revealed a substantial decline in superoxide production at the wound surface with advancing age. Older tubers were less able to respond to wounding by increasing phenylalanine ammonia lyase (PAL) activity. This enzyme produces t‐cinnamic acid, which constitutes a component of the phenolic domain of suberin, and is normally induced by wounding and/or ethylene. Interestingly, the ability of wounded tissue to oxidize exogenous 1‐aminocyclopropane‐1‐carboxylic acid (ACC) to C2H4 also decreased with advancing tuber age. The oxidation of ACC was inhibited by the FR scavenger, n‐propyl gallate (PG), and inhibition was greatest in tissue from younger tubers, reflecting their greater ability to produce superoxide radicals upon wounding. Regardless of tuber age, 1‐aminocyclobutane‐1‐carboxylic acid, an ACC oxidase inhibitor, did not inhibit C2H4 generation from exogenous ACC. Hence, C2H4 production from ACC by wounded tuber tissue is largely non‐enzymatic and FR‐driven, and thus serves as an indicator of the ability of wounded tissue to produce superoxide. Age‐induced reduction in PAL activity and FR production at the wound surface probably limited the oxidative polymerization of phenolics into suberin during wound periderm formation. The age‐induced loss in ability of wounded tissue to heal and resist pathogens is thus consistent with reduced synthesis and polymerization of phenolic adducts into suberin, a consequence of reduced FR and PAL activity at the wound surface.
Feeding and survival in parasitic wasps: sugar concentration and timing matter
Authors: Siekmann Gitta , Tenhumberg Brigitte , Keller Michael A.
Published: December 2004

Sugar consumption can increase the longevity and lifetime fecundity of many species of parasitic wasps. Consequently, for these insects the availability of sugar sources in the field is important for their reproductive success. As sugar sources can be highly variable in quantity, space and time, the chances of finding a sufficient amount of sugar to increase longevity might be very low. Therefore, the reward from a single feeding event can be critical for the forager's fitness. We measured the longevity of the parasitoid Cotesia rubecula after a single honey meal differing in sugar concentration (25, 47, 86% w/w) and timing (day of emergence and 24 h later). Survival was analysed with Cox's Proportional Hazards Model. The risk of starving to death in sugar‐fed wasps was reduced by 0–73% in comparison to unfed wasps, depending on sugar concentration and timing. Longevity was significantly increased by sugar concentration and by feeding later in life. Our results suggest that in the field, adult C. rubecula has to locate food at least once per day to avoid starvation.
Redundancy, synergism, and active inhibitory range of non‐host volatiles in reducing pheromone attraction in European spruce bark beetle Ips typographus
Authors: Zhang Qing‐He , Schlyter Fredrik
Published: December 2004

Host and habitat selection in flight by conifer bark beetles is governed by inhibition of attraction by non‐host volatiles (NHV), in addition to the well‐known attraction to kairomones from host plants and to aggregation pheromones from conspecifics. Antennally‐active NHV from angiosperm birch and aspen trees were field tested on the European spruce bark beetle, Ips typographus (L.), by pheromone baited traps in Sweden using release rates of NHV comparable to those from a non‐host tree. Trap catches were significantly reduced by 50‐70% by individual NHV: trans‐conophthorin, 3‐octanol and 1‐octen‐3‐ol from non‐host bark, 1‐hexanol and (Z)‐3‐hexen‐1‐ol from both leaves and bark and (E)‐2‐hexen‐1‐ol from leaves. Combined NHV signals in binary and ternary blends with the same overall release rates (ca 5 mg/day) showed both redundancy and synergism in their inhibitory effects. The redundancy occurred among individual green leaf alcohols (GLV‐alcohols or C6‐alcohols), C8‐alcohols, and between these two groups, while trans‐conophthorin and verbenone (Vn, from unsuitable host trees) showed significant synergistic effects between each other and with GLV‐alcohols or C8‐alcohols. The coexistence of redundancy and synergism in non‐host chemical signals may indicate different functional levels (non‐host habitats, species, and unsuitable host trees) of these negative volatile signals in the host selection process of conifer bark beetles. We showed an active inhibitory range (AIR) of a NHV‐blend plus Vn on a standard pheromone bait to be at least 2 m, by using a central pheromone trap and surrounding concentric barrier trap rings with radii of 1, 2, and 4 m. The influx of bark beetles flying across concentric rings within the AIR was reduced by 55–99%, depending on the distance to the central pipe trap. Our findings support the hypothesis that as mixed forests have greater semiochemical diversity than pure host stands; they disturb olfactory guided host choice, and may reduce the possibility of outbreaks of conifer‐infesting bark beetles. The synergistic effects as well as the active inhibitory range found in this study also suggest that optimal combinations of these NHV and verbenone may have potential in protecting forests against I. typographus by reducing or stopping attacks on suitable host trees. Mixed stands with higher semio‐chemical diversity disturb olfactory guided host choice and reduce the risk for outbreaks of specialist herbivores.. This ‘semiochemical‐diversity hypothesis’ provides new support to the general ‘stability‐diversity hypothesis’.
Global warming and the export of dissolved organic carbon from boreal peatlands
Authors: Pastor John , Solin Jeremy , Bridgham Scott D. , Updegraff Karen , Harth Cal , Weishampel Peter , Dewey Bradley
Published: December 2004

Peatlands occupy approximately 15% of boreal and sub‐arctic regions, contain approximately one third of the world's soil carbon pool, and supply most of the dissolved organic carbon (DOC) entering boreal lakes and rivers and the Arctic Ocean. The high latitudes occupied by these peatlands are expected to see the greatest amount of climatic warming in the next several decades. In addition to increasing temperatures, climatic change could also affect the position of the water‐table level and discharge from these peatlands. Changes in temperature, water tables, and discharge could affect delivery of DOC to downstream ecosystems where it exerts significant control over productivity, biogeochemical cycles, and attenuation of visible and UV radiation. We experimentally warmed and controlled water tables while measuring discharge in a factorial experiment in large mesocosms containing peat monoliths and intact plant communities from a bog and fen to determine the effects of climate change on DOC budgets. We show that the DOC budget is controlled largely by changes in discharge rather than by any effect of warming or position of the water‐table level on DOC concentrations. Furthermore, we identify a critical discharge rate in bogs and fens for which the DOC budget switches from net export to net retention. We also demonstrate an exponential increase in trace gas CO2–C and CH4–C emissions coincident with increased retention of dissolved organic carbon from boreal peatlands.
Mycorrhizal species identity affects plant community structure and invasion: a microcosm study
Authors: Stampe Elizabeth D. , Daehler Curtis C.
Published: December 2004

Previous studies have shown that arbuscular mycorrhizal fungi (AMF) can mediate plant interactions, thereby affecting plant community structure. Little is known, however, about whether the presence of different AMF species leads to differences in plant community structure or invasion success by introduced species. To investigate the effects of AMF species on community structure and invasion, we created replicate microcosms containing soil inoculated with one of three different AMF species (Glomus spurcumPfeiffer, Walker & Bloss,Scutellospora erythropa(Koske & Walker) Walker & Sanders, orScutellospora verrucosa(Koske & Walker) Walker & Sanders) or a mixture of all three AMF species. Seeds of seven naturally co‐occurring plant species (Ageratum conyzoidesL.,Cyperus compressusL.,Chamaecrista nictitans(L.),Crotalaria incanaL.,Hyptis pectinata(L.) Poit.,Sida rhombifoliaL.,Melinis repens(Willd.) Zizka) in Hawai‘i were sown equally into these microcosms, which were placed on outdoor benches. Plant community development was monitored over a season. Mid‐way through the experiment, an invader (Bidens pilosaL.) was added to the established communities to determine whether mycorrhizal species identity affected invasion success. Final aboveground and belowground phytomass were used to assess plant community differences among treatments. Although the identity of the dominant plant species (Melinis repens) remained the same in all treatments, community dominance, community productivity, plant species richness, Shannon index of diversity, and invasion success all varied with AMF species identity. Invasion success was not inversely related to species richness or diversity. Instead, increased richness, diversity, and invasion success all appeared to be related to decreased dominance byM. repensin the presence of certain AMF species. These results indicate that the composition of the AMF community belowground can influence the structure of the plant community aboveground, and may play a role in facilitating or repelling invasion.
The soil fauna community in pure and mixed stands of beech and spruce of different age: trophic structure and structuring forces
Authors: Scheu Stefan , Albers Derk , Alphei Jörn , Buryn Romuald , Klages Ute , Migge Sonja , Platner Christian , Salamon Jörg‐Alfred
Published: December 2004

This study investigates the response of the soil fauna community to replacement of beech by spruce or by mixed stands of beech and spruce. Stands of different age were investigated in a factorial design with the factors tree species (beech and spruce) and stand age (30 and 120 yr). The input of leaf/needle litter did not differ significantly between the study sites. By contrast, the amount of organic matter in upper soil layers (L/F, H/Ah) of spruce forests strongly exceeded that of beech forests particularly in mature stands. The increase in organic matter in spruce stands was not associated by an increase in the amount of microbial biomass. Biomass of eight (bacterivorous, fungivorous and omnivorous nematodes, enchytraeids, earthworms, isopodes, mycetophilid and cecidomyiid Diptera) of the twelve microbi‐detritivorous soil animal groups studied was significantly increased in beech forests; only that of one group (elaterid beetles) was increased in spruce forests and three groups did not respond significantly (collembolans, oribatid mites, sciarid Diptera). This indicates that in the forests studied neither habitat space (amount of organic matter in L/F and H/Ah layers) nor the amount of microbial biomass controlled microbi‐detritivores. Rather, the quality of litter materials and the concentration of microbial biomass therein appeared to be most important. Herbivores and predators also were favoured by beech: the biomass of one (rhizophagous nematodes) of the three herbivorous groups studied were significantly increased in beech stands and none in spruce stands; the biomass of four (predatory nematodes, centipedes, carabid and cantharid beetles) of the seven carnivorous groups studied were increased in beech stands, none in spruce stands. Generally, the biomass ratio between prey and predators was at a minimum in mature beech and mixed stands indicating more intense top‐down control in these forests. Overall, the study documents that replacement of beech by spruce strongly alters the soil food web. Mixed stands were more similar to spruce stands in respect to the biomass of soil animal groups but predator–prey interactions appeared to be more similar in mature beech and mixed stands. Differences between tree species usually were more pronounced in 120 compared to 30 yr old stands indicating that the development of stand characteristics is slow.
Coexistence of specialist parasitoids with host refuges in the laboratory and the dynamics of spatial heterogeneity in attack rate
Authors: Porter Eric E. , Hawkins Bradford A.
Published: December 2004

There is a well documented relationship between parasitoid species assemblage size and host feeding niche. Parasitoid assemblage size peaks on hosts thought to have intermediate levels of physical refuge. We examined the influence of refuges on parasitoid coexistence using pairs of specialist parasitoids in a controlled laboratory environment. Using physical barriers we excluded parasitoids from 0, 25, 50 or 75% of the hosts to simulate host refuge. We found no evidence that host refuges can promote parasitoid coexistence in a simplified laboratory environment. Results were similar whether pairs of parasitoid species were competitively disparate or competitively similar. Our results suggest that spatial heterogeneity in parasitoid attack rate was not sufficient to maintain parasitoid coexistence regardless of host refuge, and we argue that the level of spatial heterogeneity necessary to promote coexistence is rare in nature. We conclude that in most systems the coexistence of specialist parasitoids cannot be explained by a host refuge effect.
Reversed sexual dimorphism in tawny owls, Strix aluco, correlates with duty division in breeding effort
Authors: Sunde Peter , Bølstad Mikkel S. , Møller Julie D.
Published: December 2004

Even though most bird species with a raptorial feeding habit express varying extents of reversed sexual dimorphism (RSD: females bigger than males), the evolutionary basis for its maintenance, as well as its possible secondary consequences for the ecological adaptations of the different sexes, is debated. We studied pairs of tawny owls, Strix aluco (females 20% heavier than males), throughout the year by telemetry to test whether any inter‐sexual differences in movement patterns, resource partitioning and breeding effort correlated with RSD. Females were larger than males in all body size measures and were 16% heavier than would be expected from the difference in wing length alone. In accordance with predictions from flight economics, males moved longer distances per time unit than females, in particular during the post‐fledging season, when they also fed chicks more often than the females. Males had larger home ranges than females during the post‐fledging period, whereas the sexes had home ranges of equal size during the non‐breeding season. Until 10 days after fledging, females foraged much closer to the offspring than males, apparently balancing their distance to offspring between the needs of offspring guarding and foraging. In males, the parent–offspring distance only increased with decreasing brood condition. The sexes did not differ in habitat use or feeding habits, rendering no indications of food niche partitioning. The study provides further evidence that selection for males to be light and energetically efficient foragers is the main evolutionary force behind RSD in raptorial birds, even when the prey base is confined by territoriality.
Facilitation between coastal dune shrubs: a non‐nitrogen fixing shrub facilitates establishment of a nitrogen‐fixer
Authors: Rudgers Jennifer A. , Maron John L.
Published: December 2004

Understanding positive interactions among species is integral to predicting the outcomes of community‐level dynamics. Few studies have explored intraspecific variation in positive associations. We investigated facilitation between two coastal dune shrubs in California,Baccharis pilularisand the nitrogen‐fixing species,Lupinus arboreus.L. arboreusseedlings and adults were non‐randomly distributed, occurring most frequently in association withB. pilularis. The relationship depended on the genotype ofB. pilularis; only the prostrate architectural form of this species was positively associated withL. arboreus. To evaluate the nature of this association, we assessed the influence of three microhabitat types (prostrateB. pilularis,Ammophila arenaria(an introduced dune grass), and exposed sand) on four life history stages ofL. arboreus. ProstrateB. pilularisbenefitedL. arboreusseedling emergence, survival, and growth but had no effect on post‐dispersal seed predation or adult establishment. Enhanced resistances to granivory by rodents or to seedling predation by voles were not important mechanisms underlying facilitation. In addition, an experiment manipulating herbivory by cutworms found no effects of microhabitat on susceptibility to damage. Evidence supports the hypothesis that the prostrate form ofB. pilularisfacilitatesL. arboreusgermination, seedling growth, and establishment as compared to exposed sand and dune grass. Furthermore, in combination with prior research, the results suggest that by facilitating an important nitrogen‐fixer,B. pilularismay have effects that cascade to other members of the coastal plant community.
On the role of spatial stochastic models in understanding landscape indices in ecology
Authors: Fortin M.‐J. , Boots B. , Csillag F. , Remmel T.K.
Published: December 2004

Spatial stochastic models play an important role in understanding and predicting the behaviour of complex systems. Such models may be implemented with explicit knowledge of only a limited number of parameters relating to spatial relationships among locations. Consequently, they are often used instead of deterministic‐mechanistic models, which may potentially require an unrealistically large number of parameters. Currently, in contrast to spatial stochastic models, the parameterization of the joint spatial distribution of objects in landscape models is more often implicit than explicit. Here, we investigate the similarities and differences between bona fide spatial stochastic models and landscape models by focusing mostly on the relationships between processes, their realizations (patterns), representation and measurement, and their use in exploratory as well as confirmatory data analysis. One of the most important outcomes of recognizing the importance of stochastic processes is the acknowledgement that the spatial pattern observed in a landscape is only one realization of that process. Hence, while ecologists have been using landscape pattern indices (LPIs) to characterize landscape heterogeneity and/or make inferences about processes shaping the landscape, no stochastic modelling framework has been developed for their proper statistical elucidation. Consequently, several (mis)uses of LPIs draw conclusions about landscapes which are suspect. We show that several reports about sensitivities of LPIs to measurements have common roots that can be made explicitly manageable by adopting stochastic models of spatial structure. The key parameters of these stochastic models are composition and configuration, which, in general, cannot be estimated independently from each other. We outline how to develop the stochastic framework to interpret observations and make some recommendations to practitioners about everyday usage. The conceptual linkages between patterns and processes are particularly important in light of recent efforts to bridge the static‐structural and the dynamic‐analytic traditions of ecology.
Explaining variable costs of the immune response: selection for specific versus non‐specific immunity and facultative life history change
Authors: Moret Yannick
Published: December 2004

The cost of the immune response is variable and may provide a sufficient selective pressure to produce adaptations that minimise those costs under high infection prevalence. Here, using invertebrates as a model, I suggest two possible mechanisms that maintain variation in responses that covary with costs. First I propose that infection prevalence should balance costs through the selection of optimal patterns of “specific” and “non‐specific” immune pathways concomitantly expressed in the immune response. Second, I propose that life history adjustments (e.g. earlier reproduction in response to infection) could have been selected to minimise the cost of successful immune responses and consequently may result in the maintenance of costly immunity.
Biochemical and Genetic Studies of Pigment‐Type Switching
Authors: BARSH GREG , GUNN TERESA , HE LIN , SCHLOSSMAN STUART , DUKE‐COHAN JONATHAN
Published: December 2004

Mutations that affect the balance between the synthesis of eumelanin and pheomelanin provide a powerful set of tools with which to understand general aspects of cell signaling. Previous work from our laboratory has demonstrated that pheomelanin synthesis is triggered by the ability of Agouti protein to inhibit signaling through the Melanocortin 1 receptor (Mc1r). In a bioassay based on the Xenopus Mc1r, Agouti protein has two effects, competitive inhibition of receptor occupancy by α‐MSH and down‐regulation of receptor signaling, which are mediated separately by domains in the amino‐ and carboxy‐terminal regions of Agouti protein, respectively. Recently, we have used the genetics of pigmentation as an in vivo system to screen for and analyze other mutations in the Agouti–melanocortin pathway. The pigmentary effects of Agouti are suppressed by the previously existing coat‐color mutations mahogany (mg), mahoganoid (md), and Umbrous (U). Double mutant studies, with animals deficient for the Mc1r or those which carry Ay, indicate that mg and md are genetically upstream of the Mc1r, and can suppress the effects of Ay on both pigmentation and body weight. Positional cloning has recently identified the gene mutated in mahogany as a single transmembrane‐spanning protein whose ectodomain is orthologous to human Attractin (Atrn).
Regulation of Growth and Melanogenesis of Uveal Melanocytes
Authors: HU DAN‐NING
Published: December 2004

We have developed methods for the isolation, cultivation, and investigation of human uveal melanocytes (UM). Uveal melanocytes grow well and produce melanin in vitro in the presence of basic fibroblast growth factor (bFGF), cyclic adenosine monophosphate‐elevating agents, and serum. Cultured UM respond to various factors. Certain growth factors (bFGF and hepatocyte growth factor, etc.), endothelin, adrenergic β2‐receptor agonists, and some prostaglandins (EP2‐receptor agonists and certain TP‐receptor agonists) stimulate, while transforming growth factor‐β2, interleukin‐6, and cholinergic agonists inhibit melanogenesis and/or growth of UM in vitro. α‐Melanocyte‐stimulating hormone, adrenocorticotropic hormone, various sex hormones, and prostaglandin F2α showed no effect on the growth and melanogenesis of cultured UM. The stability of UM in vivo may be controlled by these factors. Disturbance of this balance may lead to certain rare pathologic pigmentary changes of the iris. UM are relatively stable in vivo; they usually do not respond (proliferate or show dynamic changes in melanogenesis) to various environmental factors. The differences of the in vivo behavior between uveal and epidermal melanocytes may be determined by both cellular factors and environmental factors.