bluuebunny/crossref_metadata_2025 huggingface dataset:
Remote glucosyltransferase‐microparticle vaccine delivery induces protective immunity in the oral cavity
Authors: Smith D. J. , Lam A. , Barnes L. A. , King W. F. , Peacock Z. , Wise D. L. , Trantolo D. J. , Taubman M. A.
Published: December 2004

Intranasally administered dental caries vaccines show significant promise for human application. Alternate mucosal routes may be required, however, to induce caries‐protective salivary IgA antibody in children with respiratory diseases. Since rectal mucosa contains inductive lymphoid tissue, we hypothesized that the rectal route could be used to induce salivary immunity to mutans streptococcal glucosyltransferase (GTF), resulting in protective immunity to experimental dental caries. We first explored the ability of glucosyltransferase, incorporated into polylactide‐co‐glycolide (PLGA) microparticles (MP), and administered rectally together with mucosal adjuvant, to induce a salivary IgA antibody response. Groups of Sprague‐Dawley rats (6/group) were immunized rectally on days 0, 7, 14 and 21 with a) GTF‐MP alone, b) GTF‐MP with cholera toxin, c) GTF‐MP with detoxified mutant Escherichia coli toxin (dLT), or d) sham immunized with PLGA and cholera toxin. An additional group was immunized intranasally with GTF‐MP alone. Saliva and nasal washes of all intranasally immunized rats contained IgA antibody to glucosyltransferase on day 28. Salivary IgA antibody was also detected in 7/12 rats rectally immunized with GTF‐MP and cholera toxin or dLT, although responses were lower than those obtained by intranasal immunization. Most fecal extracts from rectally delivered GTF‐MP plus cholera toxin or dLT rats contained IgA antibody to GTF‐MP. Low levels of fecal IgA antibody were detected in 3/6 intranasally immunized rats and 2/6 rats rectally immunized with GTF‐MP alone. We then examined the extent to which salivary IgA antibody induced by the rectal route could be protective. At 25, 31 and 38 days of age, two groups of female Sprague‐Dawley rats (13/group) were rectally immunized with GTF‐MP and cholera toxin or with empty microparticles and cholera toxin (sham group). A third group was intranasally immunized with GTF‐MP alone. After demonstrating salivary IgA responses to GTF in most GTF‐immunized rats, all animals were infected with streptomycin‐resistant Streptococcus sobrinus and placed on diet 2000. After 79 days of infection, total caries on molar surfaces were lower in both rectally (7.9 ± 1.0) and intranasally (7.1 ± 0.9; P < 0.0.03) immunized groups compared with the sham‐immunized group (11.9 ± 1.6). Smooth surface caries were significantly lower (P < 0.05) in both rectally and intranasally immunized groups. These results support the interconnectedness of the mucosal immune system and indicate that rectal immunization with GTF‐MP, together with adjuvant, or intranasal immunization with GTF‐MP alone, can induce protective levels of salivary antibody in rats.
Presenting graphical information
Authors: Bryant T. N.
Published: December 2004

This article outlines the mistakes that are commonly made when data are presented graphically. Common errors when displaying data are highlighted, and preferred solutions for avoiding these mistakes are described. The preferred approaches form the requirements that authors should meet when submitting papers to the journal of Pediatric Allergy and Immunology.
In vivo histamine release during the first minutes after deliberate sting challenges correlates with the severity of allergic symptoms
Authors: Halmerbauer G. , Hauk P. , Forster J. , Urbanek R. , Kaufmehl K. , Koller D. Y.
Published: December 2004

In this study, deliberate sting challenge was investigated as a method for estimating the severity of anaphylactic reactions in bee venom‐sensitized subjects. Twenty‐one patients with previous anaphylactic reactions to field bee sting were subjected to a deliberate sting challenge (n = 32). To document anaphylactic reactions, plasma histamine levels were measured before, and then 1 and 2 min after, bee sting challenge. Eleven patients were re‐challenged after 3–5 weeks. On 18 occasions, sting challenges caused no systemic reactions, in seven cases reactions were mild, in five moderate and in two severe. In all children showing systemic reactions, significant increases of plasma histamine were measured after 2 min. The results correlated significantly with clinical scores but not with skin prick test or with specific immunoglobulin E (IgE) and immunoglobulin G (IgG) antibodies against bee venom. In patients developing local reactions only, no increase of plasma histamine was detected. The relative amount of released histamine correlated significantly with the severity of clinical symptoms. Significant histamine release occured during the first 2 min after sting challenge in children with subsequent systemic reactions and the severity of these subsequent anaphylactic reactions correlated with plasma histamine concentrations. The measurement of plasma histamine levels in the first minutes after challenge test may therefore be used as an objective marker of a potential systemic reaction.
Delirium in the Intensive Care Unit: Occurrence and Clinical Course in Older Patients
Authors: McNicoll Lynn , Pisani Margaret A. , Zhang Ying , Ely E. Wesley , Siegel Mark D. , Inouye Sharon K.
Published: December 2004

OBJECTIVES: To describe the occurrence of delirium in a cohort of older medical intensive care unit (ICU) patients and its short‐term duration in the hospital and to determine the association between preexisting dementia and the occurrence of delirium.

DESIGN: Prospective cohort study.

SETTING: Fourteen‐bed medical ICU of an 800‐bed university teaching hospital.

PARTICIPANTS: One hundred eighteen consecutive patients aged 65 and older admitted to the ICU.

MEASUREMENTS: Baseline characteristics were obtained through surrogate interviews and medical chart review. Dementia was determined using two validated surrogate‐rated instruments. Delirium was assessed daily in the ICU using the Confusion Assessment Method (CAM) for the ICU (CAM‐ICU). After discharge from the ICU, patients were followed for up to 7 days using the CAM.

RESULTS: Delirium was present in 37 of 118 (31%) patients on admission. Only 45 patients had a normal mental status on admission, of whom 14 (31%) became delirious during their hospital stay. In the post‐ICU period, delirium occurred in 40% of patients. Almost half of patients with delirium in the ICU had persistent delirium in the post‐ICU period. Overall, 83 of 118 (70%) had delirium during hospitalization. Stupor or coma occurred in 44% of the patients overall, and 89% of survivors of stupor/coma progressed to delirium. Patients with dementia were 40% more likely to be delirious (relative risk = 1.4, 95% confidence interval = 1.1–1.7), even after controlling for comorbidity, baseline functional status, severity of illness, and invasive procedures.

CONCLUSION: Delirium is a frequent complication in older ICU patients and often persists beyond their ICU stay. Delirium in older ICU persons is a dynamic and complex process. Dementia is an important predisposing risk factor for the development of delirium in this population during and after the ICU stay.
Unsteadiness Reported by Older Hospitalized Patients Predicts Functional Decline
Authors: Lindenberger Elizabeth C. , Landefeld C. Seth , Sands Laura P. , Counsell Steven R. , Fortinsky Richard H. , Palmer Robert M. , Kresevic Denise M. , Covinsky Kenneth E.
Published: December 2004

OBJECTIVES: To determine whether a simple question about steadiness at admission predicts in‐hospital functional decline and whether unsteadiness at admission predicts failure of in‐hospital functional recovery of patients who have declined immediately before hospitalization.

DESIGN: Prospective cohort study.

SETTING: One university hospital and one community teaching hospital.

PARTICIPANTS: One thousand five hundred fifty‐seven hospitalized medical patients aged 70 and older.

MEASUREMENTS: On admission, patients reported their steadiness with walking and whether they could perform independently each of five basic activities of daily living (ADLs) at admission and 2 weeks before admission (baseline). For the primary analysis, the outcome was decline in ADL function between admission and discharge. For the secondary analysis, the outcome was in‐hospital recovery to baseline ADL function in patients who experienced ADL decline in the 2 weeks before admission.

RESULTS: In the primary cohort (n = 1,557), 25% of patients were very unsteady at admission; 22% of very unsteady patients declined during hospitalization, compared with 17%, 18%, and 10% for slightly unsteady, slightly steady, and very steady patients, respectively (P for trend = .001). After adjusting for age; medical comorbidities; Acute Physiology, Age, and Chronic Health Evaluation II score; and admission ADL, unsteadiness remained significantly associated with ADL decline (odds for decline for very unsteady compared with very steady = 2.6, 95% confidence interval = 1.5–4.5). In the secondary analysis, predicting ADL recovery in patients who declined before hospitalization (n = 563), 46% of patients were very unsteady at admission. In this cohort, 44% of very unsteady patients failed to recover, compared with 35%, 36%, and 33% for each successively higher level of steadiness, respectively (P for trend = 0.06). After multivariate adjustment, greater unsteadiness independently predicted failure of recovery (P for trend = 0.02).

CONCLUSION: A simple question about steadiness identified patients at increased risk for in‐hospital ADL decline and, in patients who lost ADL function immediately before admission, failure to recover.
Fall and Injury Prevention in Residential Care—Effects in Residents with Higher and Lower Levels of Cognition
Authors: Jensen Jane , Nyberg Lars , Gustafson Yngve , Lundin‐Olsson Lillemor
Published: December 2004

OBJECTIVES: To evaluate the effectiveness of a multifactorial fall and injury prevention program in older people with higher and lower levels of cognition.

DESIGN: A preplanned subgroup comparison of the effectiveness of a cluster‐randomized, nonblinded, usual‐care, controlled trial.

SETTING: Nine residential facilities in Umeå, Sweden.

PARTICIPANTS: All consenting residents living in the facilities, aged 65 and older, who could be assessed using the Mini‐Mental State Examination (MMSE; n = 378). An MMSE score of 19 was used to divide the sample into one group with lower and one with higher level of cognition. The lower MMSE group was older (mean ± standard deviation = 83.9 ± 5.8 vs 82.2 ± 7.5) and more functionally impaired (Barthel Index, median (interquartile range) 11 (6–15) vs 17 (13–18)) and had a higher risk of falling (64% vs 36%) than the higher MMSE group.

INTERVENTION: A multifactorial fall prevention program comprising staff education, environmental adjustment, exercise, drug review, aids, hip protectors, and postfall problem‐solving conferences.

MEASUREMENTS: The number of falls, time to first fall, and number of injuries were evaluated and compared by study group (intervention vs control) and by MMSE group.

RESULTS: A significant intervention effect on falls appeared in the higher MMSE group but not in the lower MMSE group (adjusted incidence rates ratio of falls P = .016 and P = .121 and adjusted hazard ratio P < .001 and P = .420, respectively). In the lower MMSE group, 10 femoral fractures were found, all of which occurred in the control group (P = .006).

CONCLUSION: The higher MMSE group experienced fewer falls after this multifactorial intervention program, whereas the lower MMSE group did not respond as well to the intervention, but femoral fractures were reduced in the lower MMSE group.
Meta‐Analysis of Psychosocial Interventions for Caregivers of People with Dementia
Authors: Brodaty Henry , Green Alisa , Koschera Annette
Published: December 2004

OBJECTIVES: To review published reports of interventions for caregivers (CGs) of persons with dementia, excluding respite care, and provide recommendations to clinicians.

DESIGN: Meta‐analytical review. Electronic databases and key articles were searched for controlled trials, preferably randomized, published in English from 1985 to 2001 inclusive. Thirty studies were located and scored according to set criteria, and the interventions' research quality and clinical significance were judged.

SETTING: Home or noninstitutional environment.

PARTICIPANTS: Informal CGs—persons providing unpaid care at home or in a noninstitutional setting.

MEASUREMENTS: The primary measures were psychological morbidity and burden. Other varied outcome measures such as CG coping skills and social support were combined with measures of psychological distress and burden to form a main outcome measure.

RESULTS: The quality of research increased over the 17 years. Results from 30 studies (34 interventions) indicated, at most‐current follow‐up, significant benefits in caregiver psychological distress (random effect size (ES) = 0.31; 95% confidence interval (CI) = 0.13–0.50), caregiver knowledge (ES = 0.51; CI = 0.05–0.98), any main caregiver outcome measure (ES = 0.32; CI = 0.15–0.48), and patient mood (ES = 0.68; CI = 0.30–1.06), but not caregiver burden (ES = 0.09; CI = −0.09–0.26). There was considerable variability in outcome, partly because of differences in methodology and intervention technique. Elements of successful interventions could be identified. Success was more likely if, in addition to CGs, patients were involved. Four of seven studies indicated delayed nursing home admission.

CONCLUSION: Some CG interventions can reduce CG psychological morbidity and help people with dementia stay at home longer. Programs that involve the patients and their families and are more intensive and modified to CGs' needs may be more successful. Future research should try to improve clinicians' abilities to prescribe interventions.
Psychotropic Prescription Use by Community‐Dwelling Elderly in the United States
Authors: Aparasu Rajender R. , Mort Jane R. , Brandt Heather
Published: December 2004

OBJECTIVES: To examine psychotropic prescription use in community‐dwelling elderly in the United States and its association with predisposing, enabling, and need factors.

DESIGN: Retrospective analysis of the 1996 Medical Expenditure Survey (MEPS).

SETTING: A national representative sample survey of the United States non‐institutionalized population.

PARTICIPANTS: Community‐dwelling persons aged 65 and older participating in the MEPS.

MEASUREMENTS: Psychotropic prescription use patterns and factors associated with the use of psychotropics in general as well as of individual classes, specifically antidepressants, antianxiety agents, and sedative/hypnotics.

RESULTS: According to the MEPS, more than 6 million (19%) community‐dwelling elderly persons used psychotropic medications in 1996. Nearly 3 million (9.1%) elderly were taking antidepressants, almost 2.5 million (7.5%) antianxiety agents, and 1.5 million (4.8%) sedative/hypnotics. Several correlates of psychotropic prescription use were identified. Enabling (e.g., prescription insurance) and need (e.g., health status) factors were found to be consistently associated with the use of antidepressant, antianxiety, and sedative/hypnotic agents. Predisposing factors such as sex, race, region, and education varied with the type of psychotropic drug class examined.

CONCLUSION: Nearly one in five community‐dwelling elderly persons used psychotropic medications, primarily antidepressants followed by antianxiety agents. Enabling and need factors were consistently associated with psychotropic classes examined, whereas most predisposing factors varied with the type of psychotropic drug class.
Prospective Evaluation of a Screen for Complex Discharge Planning in Hospitalized Adults
Authors: Holland Diane E. , Harris Marcelline R. , Pankratz V. Shane , Closson Diane C. , Matt‐Hensrud Natasha N. , Severson Mary A.
Published: December 2004

OBJECTIVES: To test the predictive ability of the Probability of Repeated Admission (PRA) screen for nonroutine discharge planning (requiring new referrals for formal services).

DESIGN: Prospective cohort.

SETTING: Two hospitals within a large Midwestern, tertiary care, referral‐based system.

PARTICIPANTS: Nine hundred ninety‐one hospitalized adults identified using a systematic sampling strategy.

MEASUREMENTS: The PRA screen was administered, and use of nonroutine discharge planning resources and nonroutine discharge disposition were determined using observation and open record review. Prolonged length of stay was determined by comparing the actual length of stay with the combined average length of stay for diagnosis‐related groupings.

RESULTS: Significant differences in PRA scores existed in two of three endpoints, but the differences were small, and the ranges of scores overlapped almost completely. Using, logistic regression, items predicting use of nonroutine discharge‐planning resources were self‐rated health, caregiver availability, age, and sex (chi‐square (χ2) = 105.7, df = 9, P < .001), accounting for 17.9% of the variability and area under receiver operating characteristic curve (AUC) of 0.74. Self‐rated health and sex predicted prolonged length of stay (χ2 = 15.3, df = 5, P = .009), but only explained 2.2% of the variability, with an AUC of 0.58. The predictors of nonroutine discharge disposition were self‐rated health, caregiver availability, age, sex, and diabetes mellitus (χ2 = 125.8, df = 11, P < .001), accounting for 23.0% of the variability, with an AUC of 0.79.

CONCLUSION: The clinical utility of using the PRA as a screen for early identification of persons who use nonroutine discharge planning is limited, although certain individual items may be useful.
Screening for Preexisting Cognitive Impairment in Older Intensive Care Unit Patients: Use of Proxy Assessment
Authors: Pisani Margaret A. , Inouye Sharon K. , McNicoll Lynn , Redlich Carrie A.
Published: December 2004

OBJECTIVES: To determine the prevalence of preexisting cognitive impairment (CI) in patients admitted to the medical intensive care unit (ICU) and compare two different proxy measures of preexisting CI in ICU patients.

DESIGN: Cross‐sectional comparative study.

SETTING: Urban university teaching hospital.

PARTICIPANTS: One hundred thirty patients aged 65 and older admitted to the medical ICU.

MEASUREMENTS: Two previously validated proxy measures of CI: the Modified Blessed Dementia Rating Scale (MBDRS) and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

RESULTS: The prevalence of preexisting CI in the ICU, determined using a combination of the measures, was 42%. Agreement between the two CI measures was 86%, with a kappa of 0.69, with discrepancies being related to the different domains measured by each instrument.

CONCLUSION: There is a high prevalence of preexisting CI in patients admitted to the medical ICU. Both the MBDRS and IQCODE can be used to screen for preexisting CI in situations where direct patient assessment is not feasible. Future studies are needed to address physician recognition of CI and its effect on patient care decisions and outcomes.
Kaiser Permanente Community Partners Project: Improving Geriatric Care Management Practices
Authors: Enguidanos Susan M. , Gibbs Nancy E. , Simmons W. June , Savoni Karen J. , Jamison Paula M. , Hackstaff Lynn , Griffin Anne M. , Cherin David A.
Published: December 2004

This article describes a geriatric care management project that is testing whether geriatric care management plus a brief purchase of service (POS) intervention will lower medical costs, improve satisfaction with care, increase care plan adherence, and improve perceived quality of life. Kaiser Permanente members aged 65 and older who were eligible for geriatric care management and consented to participate in the study were randomized to one of four study groups: information and referral via mail, telephone care management, geriatric care management, or geriatric care management with POS capability. The POS intervention provides up to $2,000 of designated, paid services including in‐home supportive services, transportation, respite, or medical equipment within the first 6 months of care management enrollment. Approximately 1,400 senior members were referred to the geriatric care management program, and 451 were randomly assigned to one of the four study groups. Those enrolled in the geriatric care management program were significantly more likely to be ethnic minorities and have lower income than the general Kaiser Permanente senior enrollment. Barriers encountered in implementing the POS intervention included establishing contractual agreements between Kaiser Permanente and private and community agencies, locating adequate and sufficient community agencies to provided needed services, monitoring service contracts, and delaying use of the POS benefit.
Clinical aspects and outcomes of volunteer blood donors testing positive for hepatitis‐C virus infection in Taiwan: a prospective study
Authors: Liu Chun‐Jen , Chen Pei‐Jer , Shau Wen‐Yi , Kao Jia‐Horng , Lai Ming‐Yang , Chen Ding‐Shinn
Published: December 2004

Abstract: Background/Aim: The natural history of hepatitis‐C virus (HCV) infection has been explored in volunteer blood donors, but not yet in hepatitis‐B endemic areas. Whether previous or concurrent hepatitis‐B virus (HBV) infection influences the natural history of HCV infection remains unknown. Thus, we followed the anti‐HCV‐positive blood donors who had past or concurrent HBV infection in Taiwan.

Methods: From 1992 to 1993, 1588 anti‐HCV reactive volunteer blood donors were referred to us from the Taipei Blood Center and 879 (55%) repeatedly reactive for anti‐HCV were enrolled. Two hundred and forty‐three donors (HCV RNA seropositive rate 49% by polymerase chain reaction (PCR)) received regular follow‐ups (mean period: 4.9 years) with their liver disease status determined mainly by clinical and biochemical parameters, serum alpha‐fetoprotein level and imaging studies. Hepatitis‐C virus genotype and occult HBV infection were determined by PCR‐based assays.

Results: Of the initial 879 subjects, 250 (28%) had chronic hepatitis, nine (1%) had liver cirrhosis (LC) and two (0.2%) had hepatocellular carcinoma (HCC) already. In the 243 regularly followed donors, 30% had repeatedly normal serum alanine aminotransferase (ALT) and 70% had more than once elevated ALT. Cirrhosis developed in four (1.6%; follow‐up period range: 2–6 years) and HCC in two (0.8%; follow‐up period: 3 and 4 years, respectively). Distribution of HCV genotype and hepatitis‐B surface antigen (HBsAg) did not differ between those with and those without elevation of ALT. Of the 15 donors with LC and/or HCC, only 1(7%) was positive for both HBsAg and HBV DNA and the other 14 were negative for both HBsAg and serum HBV DNA.

Conclusions: Incidentally detected hepatitis‐C was progressive in a small proportion of anti‐HCV‐positive volunteer blood donors in Taiwan. Occult HBV infection played a minimal role in the development of LC in this donor population.
Retinoic acid modulates the cell‐cycle in fetal rat hepatocytes and HepG2 cells by regulating cyclin‐cdk activities
Authors: Alisi A. , Leoni Silvia , Piacentani A. , Conti Devirgiliis L.
Published: December 2004

Abstract: Retinoic acid (RA), the most biologically active metabolite of vitamin A, is known to modulate cell proliferation, apoptosis and differentiation, with different effects depending on the cellular context. Retinoic acid can exert its effects by directly or indirectly influencing the expression of genes involved in the control of cell proliferation. In the present report we investigate the possible correlation between the antiproliferative, differentiative and apoptotic effects previously observed on rat hepatocytes and HepG2 cells, with a possible modulation of cell‐cycle regulators. We demonstrate that RA induces growth arrest and differentiation in HepG2 cells by influencing the activities of cyclin‐cdk complexes involved in the regulation of G1/S transition and S‐phase progression, in particular by modifying the binding of these complexes to p21 and p27 inhibitors. In fetal cells, however, the induction of apoptosis and differentiation by RA was obtained via inhibition of cyclin D1‐cdk4 activity, as result of an increased binding to the p16 inhibitor. Retinoic acid also modulates c‐myc and Bcl‐2 expression. In conclusion, our data suggest that RA could be useful to regulate the reversion of transformed phenotype and could also be utilized as a chemiopreventive agent in cells of hepatic origin.
How important are species richness, species evenness and interspecific differences to productivity? A mathematical model
Authors: Nijs Ivan , Roy Jacques
Published: December 2004

We present a theoretical model to quantify the influence of diversity on productivity and nutrient acquisition in plant communities during exponential growth. The model fractionates diversity into three components, namely species richness (S), species evenness (E
) and the degree of difference between species (D). The influence
of each of these components is assessed individually: S is varied
by changing the number of species, E by changing their population
size, and D by changing the range of species traits critical to
productivity (specific nutrient uptake rate, Σr,
or nutrient use efficiency, NUE). D was quantified as the
coefficient of variation of Σr or NUE. All
three components of diversity enhance the biomass and nutrient stocks in
the community, but the response patterns are different. Species richness
has a saturating influence, whereas effects of E and D are
linear and exponential, respectively. In all cases the non‐linear
dependence of productivity and nutrient acquisition on Σr and NUE during exponential growth was the single
mechanism underlying these effects. This causes the presence of plants
with extreme traits to promote productivity, and S, E and
D all affect the abundance and/or intensity of these extremes. The
model offers a framework to explain differences between experimental
observations, and suggests a concept of diversity where S and
E are structural components and D a qualitative or
functional component, which modulates the influence of the two others. We
propose to explicitly recognise D as an integral constituent of plant diversity in future studies.
Predator specificity of kairomones in diel vertical migration of Daphnia: a chemical approach
Authors: Von Elert Eric , Pohnert Georg
Published: December 2004

Daphnia responds to chemical cues released by fish with diel
vertical migration (DVM) as a behavioural predator avoidance. We used a
bioassay to characterize the chemical nature of the kairomone. Cues
released from stickleback (Gasterosteus aculeatus, Gasterosteidae)
and a piscivorous pike (Esox lucius, Esocidae) were enriched from
incubation water by reversed‐phase sorbent extraction and were reversibly
inactivated by acetylation. HPLC yielded only one active fraction with
identical retention times for the kairomones of both species. Chemical
features did not differ from those previously reported for Cyprinidae,
indicating that the active compounds are very similar if not identical.
From further investigation of the kairomone released by crucian carp
(Carassius carassius, Cyprinidae), glucuronic acids and carboxy‐,
sulphate‐ and phosphate‐groups can be excluded as essential for
biological activity. The response of Daphnia increased with increasing concentrations of extracted kairomone. The kairomone was not released from mucus by digestion with hyaluronidase. Adsorption of the kairomone to food particles seems to be of minor importance suggesting that the cue is perceived as a freely dissolved molecule.
Macrophyte and fish chemicals suppress Daphnia growth and alter life‐history traits
Authors: Burks Romi L. , Jeppesen Erik , Lodge David M.
Published: December 2004

Daphnids undergoing diel horizontal migration (DHM) to seek daytime refuge in the littoral zones of shallow lakes are likely to confront chemical cues from littoral‐associated predators and macrophytes. In field experiments, we investigated how the natural suite of chemicals occurring in a wholly vegetated lake as well as within plant‐free mesocosms with artificial macrophytes and epiphytes (either fishless or containing small fish) influenced individual daphnid growth. In laboratory experiments, we further examined how water containing chemicals from either a submerged macrophyte (waterweed, Elodea
canadensis), a planktivorous fish (roach, Rutilus rutilus) or
both impacted daphnid growth and life‐history traits. In the field, we
found the greatest suppression of daphnid growth in vials containing
water from the wholly vegetated lake relative to growth of daphnids
housed in vials containing spring water. Water from the mesocosm with
fish also suppressed daphnid growth. Daphnid growth in water from the
fishless mesocosm, which contained plastic plants colonized by epiphytes,
did not differ from that of daphnids grown in spring water. In the lab
experiment, daphnids exposed to Elodea chemicals took longer to
mature and possessed fewer eggs than daphnids in media without
Elodea chemicals. Daphnids exposed to chemicals from both
Elodea and roach reproduced the earliest and at a smaller size.
Daphnids exposed to only roach chemical cues did not significantly differ
from daphnids in control media for age or size at first reproduction
although they did possess fewer eggs. Daphnia responses to
chemicals from either roach or Elodea alone did not predict how
Daphnia responded to the combined influence of multiple chemical
cues. Our results suggest that prolonged exposure to macrophyte chemicals
incurs costs for Daphnia.
Chemical cues modify species interactions: the ecological consequences of predator avoidance by freshwater snails
Authors: Turner Andrew M. , Bernot Randall J. , Boes Christina M.
Published: December 2004

Chemical signals released by predators or injured prey often induce shifts in the traits of prey species, which may in turn affect species interactions. Here we investigate the role that chemical cues play in mediating species interactions in the littoral food web of lakes. Previous studies have shown that predators induce shifts in the morphology, life history, and behavior of the freshwater snail Physella, but the ecological consequences of developing these
inducible defenses are not well documented. We observed habitat use of
the freshwater snail Physella gyrina along a depth gradient in a
natural lake, and found they increased their use of covered habitats with
increasing depth. We hypothesized that this habitat shift was due to
changes in the level and type of predation risk, and that the habitat
shift would affect periphyton standing crops. These hypotheses were
tested in a mesocosm experiment in which we manipulated the presence of
molluscivorous fish and crayfish. Predators were confined to cages and
snail density was identical in all treatments, so any effects of
predators were mediated through trait shifts induced by chemical cues. In
the presence of fish, Physella moved under cover, but in the
presence of crayfish, Physella avoided cover and moved to the water surface. These non‐lethal effects of predators on snail habitat use influenced the interaction between snails and their periphyton resources. In the presence of fish, periphyton standing crop in covered habitats was reduced to just 8% of periphyton in the absence of fish. Crayfish had no significant effect on periphyton in covered habitats, but they reduced periphyton in near‐surface habitats to 39% of the standing crop in the absence of crayfish. The combined effects of fish and crayfish were generally intermediate to their individual effects. We conclude that because chemical cues often have strong effects on individual traits and trophic interactions are sensitive to trait values, chemical cues may play an important role in shaping the structure and dynamics of food webs.
Behavioural responses to predator chemical cues and local variation in antipredator performance in Rana temporaria tadpoles
Authors: Laurila Anssi
Published: December 2004

Antipredator behaviour is an important factor influencing survival probability of prey animals, and it may evolve rapidly as a response to changes in predator regime. I studied antipredator behaviour of common frog (Rana temporaria) tadpoles from three populations that differ
in predator regimes. In the first experiment, tadpoles obtained from four
natural matings in each population were subjected to chemical cues from
either European perch (Perca fluviatilis) or from larvae of the
dragonfly Aeshna juncea. Tadpoles decreased their activity in
response to both predators, but the spatial behaviour of tadpoles
differed between the two predator treatments. In general, there were no
differences in behaviours among the populations, but in three out of four
studied behaviours there were differences between parentages within the
populations suggesting that these behaviours may be genetically
determined. The lack of a significant Predator×Population
interaction suggests no differences in plastic antipredator behaviour
among the populations, while the lack of significant
Predator×Parentage interaction suggests no genetic variance within
the populations for plastic antipredator behaviour. In the second
experiment, tadpoles from the three populations were exposed to predation
by a free‐ranging A. juncea. In line with the first experiment,
there were no differences in survival rate between the populations. R.
temporaria tadpoles seem to rely heavily on plastic antipredator behaviour as their main response to predator chemical cues. There was very little indication of local behavioural differentiation and the possible reasons for the lack of divergence among populations are discussed.
Behavioural responses of naive Arctic charr young to chemical cues from salmonid and non‐salmonid fish
Authors: Hirvonen Heikki , Ranta Esa , Piironen Jorma , Laurila Anssi , Peuhkuri Nina
Published: December 2004

The ability to distinguish among chemical cues from multiple predators is of key adaptive value for many prey fish. We examined the attractiveness and repulsiveness of chemical stimuli from different coexisting fish species fed on different diets on the behaviour of hatchery reared Arctic charr young in a Y‐maze fluviarum, where the charr could choose between two sides either with control water or stimulus water with fish odour. We used stimuli from (1) matching sized conspecifics, large (2) Arctic charr, (3) salmon, (4) brown trout and (5) brown trout fed on Arctic charr fry. Other salmonids were given pellet food. Additional fish odour treatments included piscivorous (6) pike and (7) burbot. In the control trials both sides received control water. Arctic charr young were expected to respond adaptively to the stimuli from coexisting piscivorous fish. The charr most strongly preferred water with the odour of their matching sized conspecifics, which was the only fish odour they were familiar with before the experiments. They also showed significant preference for other salmonid odours, even though these fish are potential predators on small charr. Chemical stimuli from pike and burbot, on the contrary, were strongly avoided, and burbot odour even prevented the charr to swim and enter the lateral halves of the fluviarum. Moreover, odour from brown trout fed on Arctic charr fry was avoided when compared to stimuli from trout fed on pellets. Although the Arctic charr young were completely naive regarding piscivores, the fact that they could distinguish between different predator taxa and diets on the basis of chemical cues only reflects the long coevolutionary history of these fish populations.
Predator recognition and defence strategies in crucian carp, Carassius carassius
Authors: Pettersson Lars B. , Nilsson P. Anders , Brönmark Christer
Published: December 2004

Crucian carp from populations that lack piscivores are extremely vulnerable to predation. However, in the presence of piscivores these fish develop an inducible morphological defence, a deep body. This switch from a vulnerable, shallow‐bodied morph to a morphologically defended morph makes this species very suitable for investigations of anti‐predator strategies, and trade‐offs between morphological and behavioural defences. To address these questions, we performed eight different experiments. We found that crucian carp exhibited fright responses to chemical cues from unfamiliar predators (northern pike, perch) when these were fed prey that contained alarm substance (for northern pike: crucian carp, roach; for perch: crucian carp). Cues from small pike that were fed prey that lacked alarm substance (swordtails) caused no significant fright response whereas cues from larger pike with the same diet did. Perch on a chironomid diet elicited weaker but significant fright responses. Starved predators caused as strong fright reactions as recently fed ones did, whereas no response was exhibited towards nonpredatory fish (roach, crucian carp). Crucian carp were able to detect the presence of pike after cues had been diluted to an equivalent of 21 000 l, and larger predators elicited stronger fright responses. Prior experience of predators decreased fright responses. In particular, individuals from populations that coexisted with northern pike responded less to chemical cues from northern pike than individuals without prior experience did.  Thus, crucian carp may use both alarm‐substance related and predator‐related cues to identify predators. Further, they were able to discriminate between large and small predators. Finally, individuals from populations that coexist with predators exhibit less pronounced fright responses. These fish have an induced morphological defence, a deep body, which most likely decreases the need for strong antipredator behaviour.
Multiple predator effects on size‐dependent behavior and mortality of two species of anuran larvae
Authors: Eklöv Peter , Werner Earl E.
Published: December 2004

This study examined the effects of multiple predators on size‐specific behavior and mortality of two species of anuran larvae. Particularly, we focused on how trait changes in predators and prey may be transmitted to other species in the food web. In laboratory experiments, we examined the effects of bluegill sunfish, Lepomis macrochirus, and the odonate larva Anax junius on behavior and mortality of tadpoles of the bullfrog, Rana catesbeiana, and the green frog R. clamitans. Experiments were conducted with predators alone and together to assess effects on behavior and mortality of the tadpoles. The experiments were replicated on five size classes of the tadpoles to evaluate how responses varied with body size.

 Predation rates by Anax were higher on bullfrogs than on green frogs, and both bullfrogs and green frogs suffered greater mortality from Anax than from bluegill. Bluegill only consumed green frogs. Predation rates by both predators decreased with increasing tadpole size and decreased in the non‐lethal (caged) presence of the other predator. Both anuran larvae decreased activity when exposed to predators. Bullfrogs, however, decreased activity more in the presence of Anax than in the presence of bluegill, whereas green frogs decreased activity similarly in the presence of both predators. The largest size class of green frogs, but not of bullfrogs, exhibited spatial avoidance of bluegill. These responses were directly related to the risk posed by the different predators to each anuran species. Anax activity (speed and move frequency) also was higher when alone than in the non‐lethal presence of bluegill. We observed decreased predation rate of each predator in the non‐lethal presence of the other, apparently caused by two different mechanisms. Bluegill decreased Anax mortality on tadpoles by restricting the Anax activity. In contrast, Anax decreased bluegill mortality on tadpoles by reducing tadpole activity. We discuss how the activity and spatial responses of the tadpoles interact with palatability and body size to create different mortality patterns in the prey species and the implications of these results to direct and indirect interactions in this system.
Bayesian meta‐analysis of demographic parameters in three small, temperate passerines
Authors: Tufto Jarle , Sæther Bernt‐Erik , Engen Steinar , Arcese Peter , Jerstad Kurt , Røstad Ole Wiggo , Smith James N. M.
Published: December 2004

Accurate estimates of population parameters are vital for estimating extinction risk. Such parameters, however, are typically not available for threatened populations. We used a recently developed software tool based on Markov Chain Monte Carlo methods for carrying out Bayesian inference (the BUGS package) to estimate four demographic parameters; the intrinsic growth rate, the strength of density dependence, and the demographic and environmental variance, in three species of small temperate passerines from two sets of time series data taken from a dipper and a song sparrow population, and from previously obtained frequentist estimates of the same parameters in the great tit. By simultaneously modeling variation in these demographic parameters across species and using the resulting distributions as priors in the estimation for individual species, we improve the estimates for each individual species. This framework also allows us to make probabilistic statements about plausible parameter values for small passerines temperate birds in general which is often critically needed in management of species for which little or no data are available. We also discuss how our work relates to recently developed theory on dynamic stochastic population models, and finally note some important differences between frequentist and Bayesian methods.
Foraging and community consequences of seed size for coexisting Negev Desert granivores
Authors: Garb Jessica , Kotler Burt P. , Brown Joel S.
Published: December 2004

We examined the effects of seed size on patch use and diet selection for three co‐existing Negev Desert granivores: Allenby's gerbil (Gerbillus allenbyi), greater Egyptian sand gerbil (Gerbillus pyramidum), and crested lark (Galerida cristata). We manipulated size and spatial distribution of seeds in experimental food patches and quantified foraging behavior by measuring giving‐up densities (GUDs: the amount of food remaining in a resource patch following exploitation by a forager). In one experiment, we presented small (<1.4 mm in diameter cracked wheat), medium (2.0–3.3 mm), and large (>3.4 mm) seeds in separate trays; in a second, we presented small and medium seeds separately and mixed together. Gerbils had a higher handling time efficiency on smaller seeds, but a much higher encounter probability on larger seeds (20 times higher on large than medium seeds, and 2–5 times higher on medium than small seeds). This led gerbils to have significantly lower GUDs on larger seeds than smaller seeds and to harvest a higher proportion of the larger seeds. When presented with rich and poor patches, G. allenbyi tended to equalize GUDs in both patches, indicating a quitting harvest rate rule for patch exploitation. In contrast, larks appeared to use a fixed time rule for patch exploitation. For larks, seed size did not influence encounter probabilities, and they showed no seed‐size selectivity. Still, larks had higher handling efficiencies on smaller than larger seeds, and consequently had a significantly lower GUD on small than medium seeds. Despite large differences between the gerbils and larks in their foraging, our results do not support species coexistence via seed‐size partitioning: the larks had much higher GUDs than the gerbils on all seed sizes. Nonetheless, seed size, seed abundance, seed distribution and the animal's patch use behavior all played major roles in determining gerbils’ and larks’ diet selectivities and GUDs.
Sex differences in parasitic infections among arthropod hosts: is there a male bias?
Authors: Sheridan Letitia A. D. , Poulin Robert , Ward Darren F. , Zuk Marlene
Published: December 2004

A higher susceptibility to diseases or parasites in males than females may be an ultimate consequence of the different reproductive strategies favored by selection in the two sexes. At the proximate level, the immunosuppressant effects of testosterone in vertebrates provide a mechanism that can cause male biases in parasite infections. Invertebrates, however, lack testosterone and other steroid hormones. We used a meta‐analysis of published results to investigate whether sex biases in parasite infections were generally observed among arthropod hosts despite the absence of the immune‐endocrine coupling provided by testosterone. Overall, male and female arthropods did not differ in prevalence or intensity of parasite infections. This is based on an analysis of sex differences corrected for sample size and, when possible, variability in the original data. Sex biases in parasite infection were not more likely to be observed in certain host or parasite taxa, and were not more pronounced in experimental studies than in surveys of naturally infected hosts. Our results suggest that because of the absence of endocrine‐immune interactions in arthropods, males are not generally more prone to parasite infections than females despite the greater intensity of sexual selection acting on males.
Early effects of rodent post‐dispersal seed predation on the outcome of the plant–seed disperser interaction
Authors: Alcántara Julio M. , Rey Pedro J. , Sánchez‐Lafuente Alfonso M. , Valera Francisco
Published: December 2004

We analysed two potential effects of post‐dispersal seed predation on recruitment of the wild olive tree (Olea europaea var. sylvestris), a Mediterranean bird‐dispersed tree: (a) the limitation of abundance and distribution of seedlings after dispersal, and (b) the selection of certain seed characteristics of the recruited plants. An observational approach was used to compare seed rain among microhabitats, and how it was affected by seed predation. The relation of microhabitat, scrub density, and seed size with predation risk was explored by a field experiment. Seed density ranged from 0 seeds/m2 in open places to 93.2 seeds/m2 under O. europaea. The overall predation rate was low, as shown in the observational approach (35%). The mean percentage of predation in the experimental approach was 51%, ranging across microhabitats between 28% and 88%. It was higher in dense scrub patches (67%) than in sparse ones (33%), and lower for large seeds (42%) than for medium and small ones (57% and 55%, respectively). Finally, seed density near seed depots did not increase their probability of being detected by rodents or the predation rate. Although predation rates were low, wild olive seeds could be frequently found by rodents due to their spatial ubiquity and local abundance. Together with the efficient foraging strategy of predators (92% of experimental seed depots were found), this allowed a widespread post‐dispersal predation, but it did not modify the relative distribution of seeds among microhabitats. Thus, in our study, the seed dispersal pattern of the wild olive tree was not reshaped by post‐dispersal predation, because (1) rodents did not alter significantly its initial spatial distribution and (2) mice did not seem to limit the number of recruits. Finally, our results indicate that, as a consequence of seed size preferences of rodents, large seeds have a higher probability to survive post‐dispersal predation. Thus, seed size may be a key trait to determine the identity of the future recruits in the wild olive tree, at least affecting the characteristics of the seeds that reach the soil seed bank.