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Parasites extract part or all their resources from their host depriving them of energy that could be normally used for growth, self-maintenance or reproduction. Thus, parasites are playing a major role in the evolution of life-history traits of their host through direct or indirect fitness costs. The current experiment investigated the effect of parasitic warble flies ( Hypoderma tarandi), on the life-history traits of reindeer ( Rangifer tarandus tarandus). In autumn-winter 2005, 52 free-ranging female reindeer were administrated with an anti-parasite drug (treatment group), whereas 56 females remained untreated (control group). Subsequently, body mass, reproductive success and calf body mass were recorded in summer and winter the following year for all individuals. Reproductive success, measured as the probability of producing an offspring, was not affected by the treatment. However, the manipulation positively affected female body mass in the summer but not in the winter and a positive trend was observed for the calves during the same season. Overall, our findings indicate that warble flies have a negative impact on reindeer through their effect on body mass and consequently, are likely to affect reindeer life history and population dynamics. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The purpose of this study was to evaluate 50 human periapical lesions for bacteria and epithelium in a case study in dental practice. STUDY DESIGN: Specimens were obtained from the extraction of 50 untreated teeth that had lesions attached to their apices. The specimens were histologically evaluated using serial sections. RESULTS: Bacteria were found in all teeth, colonizing necrotic tissue in the main canal, dentinal tubules, or apical ramifications, and in the body of the periapical lesion in 18 abscesses or cysts. Twenty-one lesions were epithelialized; 14 abscesses, 20 granulomas, and 16 cysts were distinguished. In 18 root canals inflamed tissue was found in the apical part of the canal. A single foramen was present in 13 cases while apical ramifications were found in 37 cases. CONCLUSIONS: Granulomas were most common, and most epithelialized lesions were cysts. Bacteria were only detected periapically in abscesses or cysts. Inflamed tissue was present in the apical root canal in one third of cases. [ABSTRACT FROM AUTHOR]

This case demonstrates failure of root canal treatment of a maxillary central incisor following incomplete mechanical removal of a Ca(OH)2 intracanal dressing and subsequent resorption of the material from the apical portion of the root canal. Retreatment some 4 years later involved the removal of the contents of the root canal and permanent obturation by lateral condensation of cold gutta-percha with a sealer. Follow-up showed complete periradicular bone healing with a lamina dura evident. An explanation of the processes involved is offered, based upon histopathological and microbiological evidence in the literature. [ABSTRACT FROM AUTHOR]

The primary purpose of using dental materials is to restore dental and oral tissues to a healthy condition and optimal function and one must, therefore, consider equally with potential harm, the many health benefits which new materials can provide. More than 50 years ago, the first specification of the organization American Dental Association for the physical properties of amalgam was established. It may, therefore, be considered astonishing that not until now is a system for biological evaluation being introduced.

Success or failure in restorative dentistry depends equally on the physical and the biological properties of the restorative materials and the procedures necessary for their placement in the tooth. Despite this interest in the control of dental materials, it is remarkable, although understandable, that no institution found it necessary to establish specifications for the biological properties of the materials. The choice of experimental teeth has varied greatly with different investigators. The teeth of choice for intradental testing are intact human teeth from young individuals, particularly teeth to be extracted for orthodontic reasons.

The spatial and temporal distribution of forage quality is among the most central factors affecting herbivore habitat selection. Yet, for high latitude areas, forage quantity has been found to be more important than quality. Studies on large ungulate foraging patterns are faced with methodological challenges in both assessing animal movements at the scale of forage distribution, and in assessing forage quality with relevant metrics. Here we use first-passage time analyses to assess how reindeer movements relate to forage quality and quantity measured as the phenology and cover of growth forms along reindeer tracks. The study was conducted in a high latitude ecosystem dominated by low-palatable growth forms. We found that the scale of reindeer movement was season dependent, with more extensive area use as the summer season advanced. Small-scale movement in the early season was related to selection for younger stages of phenology and for higher abundances of generally phenologically advanced palatable growth forms (grasses and deciduous shrubs). Also there was a clear selection for later phenological stages of the most dominant, yet generally phenologically slow and low-palatable growth form (evergreen shrubs). As the summer season advanced only quantity was important, with selection for higher quantities of one palatable growth form and avoidance of a low palatable growth form. We conclude that both forage quality and quantity are significant predictors to habitat selection by a large herbivore at high latitude. The early season selectivity reflected that among dominating low palatability growth forms there were palatable phenological stages and palatable growth forms available, causing herbivores to be selective in their habitat use. The diminishing selectivity and the increasing scale of movement as the season developed suggest a response by reindeer to homogenized forage availability of low quality.

For long-lived organisms, the fitness value of survival is greater than that of current reproduction. Asymmetric fitness rewards suggest that organisms inhabiting unpredictable environments should adopt a risk-sensitive life history, predicting that it is adaptive to allocate resources to increase their own body reserves at the expense of reproduction. We tested this using data from reindeer populations inhabiting contrasting environments and using winter body mass development as a proxy for the combined effect of winter severity and density dependence. Individuals in good and harsh environments responded similarly: Females who lost large amounts of winter body mass gained more body mass the coming summer compared with females losing less mass during winter. Additionally, females experienced a cost of reproduction: On average, barren females gained more body mass than lactating females. Winter body mass development positively affected both the females' reproductive success and offspring body mass. Finally, we discuss the relevance of our findings with respect to scenarios for future climate change.

The Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by large herbivores and growing human activity. Thickets of tall shrubs represent a conspicuous vegetation state in northern and temperate ecosystems, where it serves important ecological functions, including habitat for wildlife. Thickets are however labile, as tall shrubs respond rapidly to both abiotic and biotic environmental drivers. Our aim was to assess how large-scale spatial variation in willow thicket areal extent, configuration and habitat structure affected bird abundance, occupancy rates and species richness so as to provide an empirical basis for predicting the outcome of environmental change for riparian tundra bird communities. Based on a 4-year count data series, obtained through a large-scale study design in low arctic tundra in northern Norway, statistical hierarchical community models were deployed to assess relations between habitat configuration and bird species occupancy and community richness. We found that species abundance, occupancy and richness were greatly affected by willow areal extent and configuration, habitat features likely to be affected by intense ungulate browsing as well as climate warming. In sum, total species richness was maximized in large and tall willow patches of small to intermediate degree of fragmentation. These community effects were mainly driven by responses in the occupancy rates of species depending on tall willows for foraging and breeding, while species favouring other vegetation states were not affected. In light of the predicted climate driven willow shrub encroachment in riparian tundra habitats, our study predicts that many bird species would increase in abundance, and that the bird community as a whole could become enriched. Conversely, in tundra regions where overabundance of large herbivores leads to decreased areal extent, reduced height and increased fragmentation of willow thickets, bird community richness and species-specific abundance are likely to be significantly reduced.

Aim: The aim of this study is to illuminate nurses' experiences of being in ethically difficult situations in an emergency ward., Background: Nurses working in emergency practice are frequently faced with ethical issues and challenges in their work. Many studies have been conducted concerning ethical challenges, but no empirical studies related to ethics in emergency wards in Norway have been carried out., Design: A qualitative interview study was conducted., Method: Five registered nurses were interviewed about their experiences in an emergency ward in a hospital in Norway. The concept of ethically difficult situations was not defined that the question was left open for the respondents themselves to define what they experienced as ethically difficult. A phenomenological hermeneutical method was used., Results: The most salient point revealed by the study is the enormous difficulty associated with the prioritisation of tasks and the attendant sense of responsibility which this entailed, particularly in the case of nurses in charge. The narratives reveal the vulnerability of the nurses in ethically challenging situations., Conclusions: Despite the pressure of responsibility for their patients, the nurses enjoy a sense of satisfaction in their work. Those recognising the ethical dimension in their own professional practice are unable to hide behind others and thus evade their share of the responsibility., Relevance to Clinical Practice: Nurses with similar experiences may find the results credible recognising the descriptions or interpretations and seeing them in relation to similar situations. Nurses working on medical and surgical wards, in nursing homes and community care may also feel a great responsibility, difficulties in prioritising and a lack of time for the patients., (© 2011 Blackwell Publishing Ltd.)

Organisms should adopt a risk-sensitive reproductive allocation when summer reproductive allocation competes with survival in the coming winter. This trade off is shown through autumn female body mass, which acts as an insurance against unpredictable winter environmental conditions. We tested this hypothesis on female reindeer in a population that has experienced a time period of dramatic increase in abundance. Environmental conditions during winter were fairly stable (with the exception of 1 year). We conclude that increased population abundance (perhaps in interaction with winter environmental conditions) could have represented a worsening of winter environmental conditions as both autumn offspring and spring female body mass decreased during the course of the study. Moreover, we found that the cost of reproduction was related to environmental conditions as: (1) autumn body mass was larger for barren than for lactating females, and this difference was temporally highly variable; (2) lactating females produced smaller offspring than barren ones in the following year; and (3) reproductive output (offspring size) decreased over time. We also found evidence of quality effects as lactating females had a higher reproductive success in the following year. In sum, a worsening of winter conditions lead to: (1) decreased reproductive output; (2) lowered autumn body mass for lactating females; and (3) increased body mass for barren females. Since females reduce their reproductive allocation as winter conditions becomes more severe, we conclude that reindeer have adopted a risk-sensitive reproductive allocation.

When reproduction competes with the amount of resources available for survival during an unpredictable nonbreeding season, individuals should adopt a risk-sensitive regulation of their reproductive allocation. We tested this hypothesis on female reindeer (Rangifer tarandus), which face a trade-off between reproduction and acquisition of body reserves during spring and summer, with autumn body mass functioning as insurance against stochastic winter climatic severity. The study was conducted in a population consisting of two herds: one that received supplementary winter feeding for four years while the other utilized natural pastures. The females receiving additional forage allocated more to their calves. Experimental translocation of females between the herds was conducted to simulate two contrasting rapid alterations of winter conditions. When females receiving supplementary feeding were moved to natural pastures, they promptly reduced their reproductive allocation the following summer. However, when winter conditions were improved, females were reluctant to increase their reproductive allocation. This asymmetric response to improved vs. reduced winter conditions is consistent with a risk-averse adjustment in reproductive allocation. The ability of individuals to track their environment and the concordant risk-sensitive adjustment of reproductive allocation may render subarctic reindeer more resilient to climate change than previously supposed.

Objective: The purpose of this study was to evaluate 50 human periapical lesions for bacteria and epithelium in a case study in dental practice., Study Design: Specimens were obtained from the extraction of 50 untreated teeth that had lesions attached to their apices. The specimens were histologically evaluated using serial sections., Results: Bacteria were found in all teeth, colonizing necrotic tissue in the main canal, dentinal tubules, or apical ramifications, and in the body of the periapical lesion in 18 abscesses or cysts. Twenty-one lesions were epithelialized; 14 abscesses, 20 granulomas, and 16 cysts were distinguished. In 18 root canals inflamed tissue was found in the apical part of the canal. A single foramen was present in 13 cases while apical ramifications were found in 37 cases., Conclusions: Granulomas were most common, and most epithelialized lesions were cysts. Bacteria were only detected periapically in abscesses or cysts. Inflamed tissue was present in the apical root canal in one third of cases.

The results of an in vivo histological study involving apical and periapical tissues following root canal therapy after different observation periods demonstrated the most favourable histological conditions when the instrumentation and obturation remained at or short of the apical constriction. This was the case in the presence of vital or necrotic pulps, also when bacteria had penetrated the foramen and were present in the periapical tissues. When the sealer and/or the gutta-percha was extruded into the periapical tissue, the lateral canals and the apical ramifications, there was always a severe inflammatory reaction including a foreign body reaction despite a clinical absence of pain.

Three cases of mandibular second molars with C-shaped root canal morphology are described. Two of these molars did not radiographically show the usual anatomic configuration of two separated roots, but rather had a single conical root. Only two root canals orifices were observed in the pulp chamber floor: a mesial-lingual orifice in its normal position and a buccal C-shaped fissure that was continuous from the normal location of the mesiobuccal canal to that of the distal canal. The fissure became smaller in the apical third, ending in a distal direction. The third case, a second molar extracted because of severe periodontal involvement showed, after sectioning, a C-shaped root with connections between all three canals.

The purpose of this study was to develop methods and criteria for the testing of the biocompatibility of endodontic materials. One hundred twenty-one teeth from 12 baboons (Papio anubis) were used to test three sealers: AH26, Kerr pulp canal sealer, and Kloroperka N.O. Gutta-percha cones were used as solid core in all cases. Under disinfected conditions, access preparation was performed, and with working length approximately 1.0 mm short of the foramen, the instrumentation of the root canal was started, using sodium hypochlorite (1%) for irrigation. After the root canals were cleaned and shaped, they were obturated with gutta-percha cones and the sealer, and by lateral condensation technique. Histologic periapical reactions were evaluated at 1, 7, 30, 365, 730, and 1095 days. The methods and criteria used were adequate for ranking of the biocompatibility of the tested materials in the short and long periods. At short observation periods (1 to 7 days) AH26 caused severe reactions, and Kerr pulp canal sealer and Kloroperka N.O., moderate and mild reactions, respectively. At 2- and 3-year observation periods the ranking was AH26, mild; Kerr pulp canal sealer, moderate; and Kloropercha N.O., severe.

One hundred fifty cases of endodontic treatment failures were studied clinically, radiographically, and histologically. Fifty-seven percent of the teeth were asymptomatic. Pain alone and/or associated with swelling was present in 21% of the teeth. There was no correlation between the size of periradicular rarefaction and the occurrence or severity of clinical signs and/or symptoms. Stainable bacteria were demonstrated in 69% of the teeth and were present mostly in the canal. The severity of periradicular inflammation was related to presence of stainable bacteria in the canal. Swelling and pain or a draining sinus tract was often associated with stainable bacteria inside the canal. The development of a radicular cyst associated with an endodontically treated tooth that has failed is not necessarily the cause of endodontic treatment failure.

A random sample of 967 subjects selected from the total population in a Swedish county were examined radiographically regarding prevalence and quality of endodontic treatment and occurrence of periapical lesions. The relationship between the technical standard of endodontic treatment and the occurrence of periapical lesions was also analyzed. Of the selected individuals, 95% attended examination (751 dentate and 169 edentulous individuals). Of the 17,430 teeth examined, 1,492 (8.6%) were endodontically treated. Approximately 70% of the treated root canals were inadequately obturated; 10% showed excess of root filling beyond the apex. The prevalence of periapical lesions was 2.9%, and 24.5% of the endodontically treated roots demonstrated periapical lesions. Root fillings ending more than 2 mm from apex had a significantly lower frequency of periapical lesions than root fillings ending within 2 mm of the apex. No difference in the frequency of periapical lesions was found between properly and improperly obturated root canals. Excess of root filling material beyond the apex was related to a significantly higher frequency of periapical lesions.

Dentinal tubules of the root canal walls of human teeth were infected in vitro with a known bacterial isolate. The roots were exposed to either calcium hydroxide or iodine potassium-iodide for various periods of time and the viability of microorganisms was determined by incubation of entire root samples in a culture medium. The effects of the two agents on microbial viability were evaluated and compared. Iodine potassium-iodide disinfected dentin effectively. In contrast, bacteria remained viable in the dentin after relatively extended periods of calcium hydroxide treatment.