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Summary: Intra‐operative hypotension is a risk factor for postoperative morbidity and mortality. Minimally invasive monitors that derive other haemodynamic parameters, such as stroke volume, may better inform the management of hypotension. As a prelude to a multicentre randomised controlled trial, we conducted a single‐centre feasibility trial of a protocol to treat hypotension as informed by minimally invasive haemodynamic monitoring during non‐cardiac surgery. We recruited adults aged ≥40 years with cardiovascular risk factors who underwent non‐cardiac surgery requiring invasive arterial pressure monitoring. Participants were randomly allocated to usual care, or a clinical protocol informed by an arterial waveform contour analysis monitor. Participants, outcome assessors, clinicians outside operating theatres and analysts were blinded to treatment allocation. Feasibility was evaluated based on: consent rate; recruitment rate; structured feedback from anaesthesia providers; and between‐group differences in blood pressure, processes‐of‐care and outcomes. The consent rate among eligible patients was 33%, with 30 participants randomly allocated to the protocol and 30 to usual care. Anaesthesia providers rated the protocol to be feasible and acceptable. The protocol was associated with reduced fluid balance and hypotension exposure in the peri‐operative setting. Postoperative complications included: acute myocardial injury in 18 (30%); acute kidney injury in 17 (28%); and surgical site infection in 7 (12%). The severity of complications was rated as moderate or severe in 25 (42%) participants. In summary, this single‐centre study confirmed the feasibility of a multicentre trial to assess the efficacy and safety of a physiologically guided treatment protocol for intra‐operative hypotension based on minimally invasive haemodynamic monitors. [ABSTRACT FROM AUTHOR]

Background It is necessary to determine the incidence and risk factors for tuberculosis ( TB), as well as strategies to assess and treat latent tuberculosis infection ( LTBI) in lung transplant recipients. Methods A retrospective cohort study of 398 lung transplant recipients was performed. Episodes of TB were studied and the incidence rate was calculated. Logistic regression analysis was used to analyze specific variables as potential risk factors for TB. Results Median follow-up was 558 days (range 1-6636). Six cases (1.5%) of TB were documented in 398 transplant patients. The incidence density of TB was 406.3 cases/105 patient-years (95% confidence interval [ CI] 164.7-845), which is higher than in the general population (13.10 cases/105 person-years). All cases occurred in the period 1993-2006, when the tuberculin skin test ( TST) and treatment of LTBI in positive TST patients were not part of the protocol. Pretransplant computed tomography ( CT) showed residual lesions in 50% of patients who developed TB, although the TST was negative and the chest radiograph was inconclusive. Multivariate analysis identified the presence of residual lesions in the pretransplant chest CT (odds ratio [ OR] 11.5, 95% CI 1.9-69.1, P = 0.008), use of azathioprine ( OR 10.6, 95% CI 1.1-99.1, P = 0.038), and use of everolimus ( OR 6.7, 95% CI 1.1-39.8, P = 0.036) as independent risk factors for TB. Conclusions Residual lesions in the pretransplant chest CTs and the use of azathioprine and mTOR inhibitors are associated with the risk of TB. [ABSTRACT FROM AUTHOR]

Many species show diet-induced flexibility of activity of intestinal enzymes; however, molecular and genetic mechanisms responsible for such modulation are less known, particularly in altricial birds. The goal of our study was to test whether a diet-induced increase in activity of intestinal maltase and sucrase in house sparrow nestlings is matched with an increase in maltase-glucoamylase ( MG) and sucrase-isomaltase ( SI) complex mRNAs respectively. Both enzyme activities were significantly higher in mid-intestine of nestlings fed a medium-starch ( MS) diet compared to those fed a starch-free ( SF) diet. In contrast to the similar pattern of dietary induction for both enzyme activities, diet MS elevated significantly only the level of MG mRNA, but not SI mRNA. The coordinated increase in activity of maltase and in MG mRNA is consistent with the hypothesis that dietary induction of this enzyme is under transcriptional control. In contrast, the lack of such coordination for changes in activity of sucrase and SI mRNA suggests that upregulation of this enzyme may be achieved by post-translational factor(s). We conclude that genetic mechanisms responsible for diet-induced flexibility of digestive enzymes in birds may differ from that observed in mammals. [ABSTRACT FROM AUTHOR]

Tomato spotted wilt virus ( TSWV) causes economically important losses in many crops, worldwide. In pepper ( Capsicum annuum), the best method for disease control has been breeding resistant cultivars by introgression of gene Tsw from Capsicum chinense. However, this resistance has two drawbacks: (a) it is not efficient if plants are infected at early growth stages and under prolonged high temperatures, and (b) it is rapidly overcome by TSWV evolution. In this work, we selected and evaluated a new accession from Capsicum baccatum, named PIM26-1, using a novel approach consisting in measuring how three parameters related to virus infection changed over time, in comparison to a susceptible pepper variety (Negral) and a resistant (with Tsw) accession ( PI-159236): (a) The level of resistance to virus accumulation was estimated as an opposite to absolute fitness, W=e r, being r the viral multiplication rate calculated by quantitative RT-PCR; (b); the level of resistance to virus infection was estimated as the Kaplan-Meier survival time for no infection using DAS-ELISA to identify TSWV-infected plants; (c) the level of tolerance was estimated as the Kaplan-Meier survival time for no appearance of severe symptoms. Our results showed that the levels of both resistance parameters against TSWV wild type ( WT) and Tsw-resistance breaking ( TBR) isolates were higher in PIM26-1 than in the susceptible pepper variety Negral and similar to the resistant variety PI-159236 against the TBR isolate. However, PIM26-1 showed a very high tolerance (none of the plants developed severe symptoms) to the WT and TBR isolates in contrast to Negral for WT and TBR or PI-159236 for TBR (most TSWV-inoculated plants developed severe symptoms). All this indicate that the new accession PIM26-1 is a good candidate for breeding programmes to avoid damages caused by TSWV TBR isolates in pepper. [ABSTRACT FROM AUTHOR]

Seabirds are particularly vulnerable to introduced alien mammalian predators, especially invasive rats, which are the main contributors to seabird extinction and endangerment in many places worldwide. However, this appears context-dependent because, paradoxically, cases of apparent long-term coexistence between rats and some species of seabird have been reported for centuries, in various locations. Among seabirds, procellariiforms are known to have developed a range of olfactory-driven behaviours, such as partner recognition and homing. Olfaction could be an effective means of recognizing and thereafter avoiding invasive predators. However, the role of olfaction in predation risk assessment has not yet been examined in any procellariiform. Here, we investigated, through a Y-maze experiment, whether the wedge-tailed shearwater ( P uffinus pacificus) avoided the odour of one of the most damaging alien predators on islands, the ship rat ( R attus rattus). The experiment was conducted in different ecological contexts on three neighbouring islets off New Caledonia having different communities of invasive rats. Contrary to our expectations, the wedge-tailed shearwater either did not detect or did not avoid the odour of the ship rat, despite about 175 years of coexistence between rats and shearwaters in New Caledonia. These findings highlight the need for further investigations (across species, across sites) into the factors underpinning the paradox between high vulnerability and the surprising long-term coexistence between procellariid seabirds and alien invasive rats. [ABSTRACT FROM AUTHOR]

Huanglongbing (HLB) disease is seriously threatening and/or damaging the citrus industry worldwide. Accurate detection of the three species associated with HLB disease, 'Candidatus Liberibacter asiaticus', 'Candidatus Liberibacter africanus' and 'Candidatus Liberibacter americanus', is essential for the preventive control of the disease. Real-time PCR is a useful tool for bacterial detection. However, nucleic acid purification steps limit the number of samples that can be processed by PCR. Universal detection of 'Ca. Liberibacter' species was achieved by direct tissue-printing and spotting of plant leaf petiole extracts or squashing of individual psyllids onto paper or nylon membranes. Primers were designed and used with TaqMan chemistry for accurate detection of the bacterium in immobilized targets (prints of 10 overlapping leaf pedicels per tree, or squashed single vectors), by extraction with water and direct use for real-time PCR. This simplified method was validated and could detect HLB-liberibacters in 100% of leaves with symptoms and 59% of symptomless leaves collected from HLB-infected trees. The use of direct assays as template showed good agreement with use of purified DNA (κ = 0·76 ± 0·052). The squash assay allowed detection of the bacterium in 40% of mature Diaphorina citri that fed on leaves of HLB-infected trees with or without symptoms. A commercial ready-made kit based on this technology showed 96% accuracy in intra-laboratory performance studies. The simplified direct methods of sample preparation presented herein can be effectively adopted for use in rapid screening of HLB agents in extensive surveys, certification schemes or for epidemiological and research studies. [ABSTRACT FROM AUTHOR]

Context Between December 2010 and January 2011, 20 cases of mycobacteriosis, consisting of grossly nodular granulomatous and caseous lesions in pig carcases from five different fattening farms, were submitted to the Slaughterhouse Support Service in Barcelona, Spain. Lesions involved lymph nodes, lungs, liver and spleen. Main conclusion A mycobacteriosis outbreak caused by Mycobacterium avium subspecies avium was detected in the five pig farms. Approach Gross pathology, histopathology and bacteriological isolation followed by molecular identification of culture isolates and epidemiological investigation. Results Histopathological examination showed multifocal to coalescent, granulomatous and necrotising lymphadenitis, pneumonia, hepatitis and splenitis. Acid-fast bacilli compatible with mycobacteria were detected in some of the samples. The presence of acid-fast bacilli in some cases revealed mycobacteriosis. Bacteriological culture was performed to confirm diagnoses and identify the aetiological agent (to rule out potential involvement of Mycobacterium tuberculosis complex mycobacteria, which includes those that cause human and animal tuberculosis). PCR from culture isolates confirmed the growth of M avium complex. Further sequencing analysis determined it was M avium subspecies avium. Interpretation The most likely source of the outbreak was considered to be the feed that was shared by the five farms, which might have been contaminated with M avium subspecies avium. The fact that most of the animals presented with a clear involvement of abdominal viscera is consistent with an oral route of infection. Significance of findings The establishment of a meat inspection support network allowed for rapid management of sample submission, diagnosis and subsequent molecular identification of the mycobacteriosis outbreak, leading to an understanding of the associated risks to public health. [ABSTRACT FROM AUTHOR]

The application of horticultural mineral oil ( HMO) treatments has been reported as a possible control strategy to reduce Plum pox virus ( PPV) incidence in Prunus nurseries. The effect of Sunspray Ultrafine HMO at 1% on the natural viral spread was evaluated in experimental nursery plots of Nemaguard and Mariana GF8-1 Prunus rootstock blocks established under high natural inoculum pressure of the most prevalent PPV-types. Tests were conducted in experimental nursery plots in Plovdiv, Bulgaria ( PPV-M and PPV-Rec), in Bistrita, Romania ( PPV-D and PPV-Rec) and in Llíria, Spain ( PPV-D). Horticultural mineral oil treatments were applied weekly during the vegetative period from spring to fall (treatments were interrupted in the summer). Nursery plants were analysed yearly by double-antibody sandwich enzyme-linked immunosorbent assay with 5B-IVIA/ AMR monoclonal antibodies. The population dynamics of the aphids visiting plants in each experimental nursery plot was monitored by the sticky-shoot method and also by Moericke yellow water traps. At all three locations, the aphid population first peaked in the springtime. Furthermore, a variable second peak of aphid population was observed in Plovdiv and Bistrita in autumn. The treatments reduced PPV incidence in the three experimental locations and plots and in both assayed Prunus rootstocks grown under high PPV-inoculum pressure. A reduction from 10% to 20% of PPV-incidence between treated and control plants ( P < 0.05) in Plovdiv and Bistrita, respectively, was observed at the end of the tests. However, HMO treatments did not prevent PPV infection altogether, probably because of the high PPV prevalence in the area near the experimental nursery blocks. The control of PPV in nursery blocks based on HMO is presented as an environmentally friendly strategy based on the physical action of the treatments. [ABSTRACT FROM AUTHOR]

Background Urinary tract infection (UTI) is the most common infection in renal transplant patients, but it is necessary to determine the risk factors for bacterial UTI in recipients of other solid organ transplants ( SOTs), as well as changes in etiology, clinical presentation, and prognosis. Methods In total, 4388 SOT recipients were monitored in 16 transplant centers belonging to the Spanish Network for Research on Infection in Transplantation ( RESITRA). The frequency and characteristics of bacterial UTI in transplant patients were obtained prospectively from the cohort ( September 2003 to February 2005). Results A total of 192 patients (4.4%) presented 249 episodes of bacterial UTI (0.23 episodes per 1000 transplantation days); 156 patients were kidney or kidney-pancreas transplant recipients, and 36 patients were liver, heart, and lung transplant recipients. The highest frequency was observed in renal transplants (7.3%). High frequency of cystitis versus pyelonephritis without related mortality was observed in both groups. The most frequent etiology was Escherichia coli (57.8%), with 25.7% producing extended-spectrum β-lactamase ( ESBL). In all transplants but renal, most cases occurred in the first month after transplantation. Cases were uniformly distributed during the first 6 months after transplantation in renal recipients. Age (odds ratio [ OR] per decade 1.1, 95% confidence interval [ CI] 1.02-1.17), female gender ( OR 1.74, 95% CI 1.42-2.13), and the need for immediate post-transplant dialysis ( OR 1.63, 95% CI 1.29-2.05) were independent variables associated with bacterial UTI in renal and kidney-pancreas recipients. The independent risk factors identified in non-renal transplants were age ( OR per decade 1.79, 95% CI 1.09-3.48), female gender ( OR 1.7, 95% CI 1.43-2.49), and diabetes ( OR 1.02, 95% CI 1.001-1.040). Conclusions UTI was frequent in renal transplants, but also not unusual in non-renal transplants. Because E. coli continues to be the most frequent etiology, the emergence of ESBL-producing strains has been identified as a new problem. In both populations, most cases were cystitis without related mortality. Although the first month after transplantation was a risk period in all transplants, cases were uniformly distributed during the first 6 months in renal transplants. Age and female gender were identified as risk factors for UTI in both populations. Other particular risk factors were the need for immediate post-transplant dialysis in renal transplants and diabetes in non-renal transplants. [ABSTRACT FROM AUTHOR]

The Pampas fox ( Pseudalopex gymnocercus) is a generalist South American canid that adapts well to the human-dominated landscape of the Argentine pampas, which is largely converted to agriculture and pastures. However, little is known about its ranging behaviour and spatial organization in relict native grasslands. We captured and tracked 13 radio-tagged adult foxes between December 1998 and June 2005 in Ernesto Tornquist Provincial Park, a protected area with a dense population of wild horses, an important food item for foxes. The home range of 10 adult males averaged 1.40 ± 0.96 km2 (mean ± sd; 95% minimum convex polygon, MCP) and was not significantly larger than that of three adult females, 1.20 ± 1.07 km2 (95% MCP). Evidence of individual's site fidelity over the study period is indicative of locally abundant food resources all year round. It is likely that the availability of horse carcasses is a main driver of the spatial organization of Pampas foxes in this population. Our population density estimate of 1.1-1.5 foxes per km2 falls within the know range of population densities for Pampas foxes, and was close to the upper limit, as also expected from an abundant and aggregated food resource such as horse carrion. Reduced hunting pressures, however, may also contribute to explain the relatively high population densities of foxes in this protected area. [ABSTRACT FROM AUTHOR]

The control of Plum pox virus (PPV), the most important viral disease that affects stone fruit trees, requires the use of reliable detection methods. The effectiveness of spot real-time reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of PPV in samples collected from nursery blocks was compared with a validated PPV detection technique, the double antibody sandwich indirect enzyme-linked immunosorbent assay (DASI-ELISA) using the PPV-specific monoclonal antibody 5B-IVIA/AMR. In total, 5047 nursery plants were analysed by both techniques. The agreement between the techniques was almost perfect (Cohen's kappa index of 0·88 ± 0·01). The diagnostic parameters (sensitivity, specificity and likelihood ratios) of both techniques were simultaneously evaluated in 2473 nursery plants by latent class models using maximum likelihood functions and a Bayesian approach. The sensitivity and specificity of both techniques did not vary according to the latent model applied. Spot real-time RT-PCR was more sensitive while DASI-ELISA was more specific for PPV detection. In addition, the findings demonstrate that latent class models are a flexible and potent statistical method to estimate the accuracy of diagnostic tests for plant pathology. [ABSTRACT FROM AUTHOR]

Invasive rats ( Rattus spp.) are renowned bird predators and have been identified as a leading cause of island bird population declines and extinctions. Recently, new questions have been raised regarding the mechanisms and the severity of impact of invasive rat predation on bird populations. We investigated the predatory capacity of the invasive black rat Rattus rattus on bird eggs using captive trials on wild-trapped individuals. Five factors were specifically tested for their influence on egg predation success: egg size, egg state, rat body mass, gender and habitat. Our results showed that rats only managed to prey on intact eggs when these were small (canary) and that they had great difficulty preying on medium-sized (hen) and even small (quail)-sized intact eggs, regardless of the rat' body mass, gender and habitat. Conversely, rats preyed extensively on previously damaged eggs of all sizes. Our findings suggest that preying on intact bird eggs without specific learning skills, such as rolling an egg to break it, may be challenging for the black rats. Moreover, our findings strongly indicate that bird susceptibility to egg predation by rats varies with island contexts and may depend on a combination of multiple additive and synergic factors. Experiments that allow for testing the multiple evolutionary and ecological factors explaining between-island or between-population variation in rodent impacts are needed to promote a better overview of the processes involved in bird population declines. [ABSTRACT FROM AUTHOR]

Introduced predators on islands are responsible for numerous native species extirpations and extinctions. Predation by cats is particularly detrimental to seabirds and cat control or eradication is generally the best option to reduce their negative impacts on native fauna. However, potential cascading effects, such as mesopredator release effect, need to be monitored after cat removal. In Port-Cros Island, a cat control campaign was undertaken to eliminate the strong and recurrent threat from feral cat predation to the small yelkouan shearwater Puffinus yelkouan population, without harming a neutered domestic cat population. To evaluate the conservation value of this campaign for an island endemic and endangered species, the diet and impact of the remaining domestic cats were studied through scat analysis and trap success. Moreover, to evaluate the recovery of the seabird population and detect any potential mesopredator release effect, shearwater and rat populations were monitored before, alongside and after the cat control. Only live traps were used, and most cats were trapped in the first year of cat eradication. The last incidence of cat predation on the yelkouan shearwater occurred the following year. The recovery of the shearwater population, occurring the first year of cat control, was mainly attributable to the settlement of new breeders in the colony. Rat population dynamics fluctuated widely but, even though the interactions between rats and shearwaters at breeding cavities increased, no evidence of rat predation on shearwaters was recorded. Thus, cat control on Port-Cros Island was a success for native species conservation, proving that such management strategy can induce an increase in the population of the endemic species, here the yelkouan shearwater, without any evidence of a mesopredator release effect. [ABSTRACT FROM AUTHOR]

Diabetic neuropathy is one of the most frequent complications in diabetes but there are no treatments beyond glucose control, due in part to the lack of an appropriate animal model to assess an effective therapy. This study was undertaken to characterize the degenerative and regenerative responses of peripheral nerves after induced sciatic nerve damage in transgenic rat insulin I promoter / human interferon beta (RIP/IFNbeta) mice made diabetic with a low dose of streptozotocin (STZ) as an animal model of diabetic complications. In vivo, histological and immunohistological studies of cutaneous and sciatic nerves were performed after left sciatic crush. Functional tests, cutaneous innervation, and sciatic nerve evaluation showed pronounced neurological reduction in all groups 2 weeks after crush. All animals showed a gradual recovery but this was markedly slower in diabetic animals in comparison with normoglycemic animals. The delay in regeneration in diabetic RIP/IFNbeta mice resulted in an increase in active Schwann cells and regenerating neurites 8 weeks after surgery. These findings indicate that diabetic-RIP/IFNbeta animals mimic human diabetic neuropathy. Moreover, when these animals are submitted to nerve crush they have substantial deficits in nerve regrowth, similar to that observed in diabetic patients. When wildtype animals were treated with the same dose of STZ, no differences were observed with respect to nontreated animals, indicating that low doses of STZ and the transgene are not implicated in development of the degenerative and regenerative events observed in our study. All these findings indicate that RIP/IFNbeta transgenic mice are a good model for diabetic neuropathy. [ABSTRACT FROM AUTHOR]

The distribution of interstitial cells of Cajal (ICC) and neurotransmission were investigated in lower oesophageal sphincter (LES) circular muscle strips from Sprague–Dawley (SD) rats, Ws/Ws mutant rats and their wild-type (+/+) siblings. Intramuscular c-Kit-positive cells, confirmed to be ICC-IM by electron microscopy, were observed throughout both muscle layers from SD and +/+ rats. In contrast, c-Kit-positive, ultrastructurally typical ICC-IM were absent in Ws/Ws. LES strips from Ws/Ws rats showed increased spontaneous contractile activity. Strips from SD and +/+ rats, responded to electrical neuronal stimulation with a relaxation that was in part L-NNA and in part apamin sensitive, followed by a contraction which was decreased by atropine. In Ws/Ws rats, similar to +/+ rats, neurally mediated relaxation was L-NNA and apamin sensitive and the contraction was decreased by atropine. We conclude that in the rat LES, relaxation is mediated by NO and an apamin-sensitive mediator, and contraction primarily by acetylcholine. Despite the absence of c-Kit-positive ICC, nerve–muscle interaction can be accomplished likely by diffusion of neurotransmitters to the smooth muscle cells. The lack of c-Kit-positive ICC is related to an increase in the basal tone and spontaneous contractile activity. The presence of fibroblast-like ICC in Ws/Ws rats might represent immature ICC whose possible functions need further investigation. [ABSTRACT FROM AUTHOR]

The distribution and global habitat association of the North African houbara bustard (Chlamydotis undulata sensu stricto) were studied for the first time in a large semi-arid steppe-land region in eastern Morocco. The study area has been protected from hunting for 6 years, but was still under significant pressure from grazing activities. Houbara distribution was assessed using point count surveys conducted during the 2002 breeding season and compared to natural- and human-related predictors. The hierarchy and quantification of influences was evaluated using a discriminant function analysis. Micro-topography first drove houbara bustard distribution, since birds were usually found in open flat tracts allowing visibility over a long distance for the prevention of potential predator approaches, but also for breeding males to be seen by conspecifics. 'Flooding surfaces' presenting concealment possibilities, as well as readily available food resources, were secondly sought. Proximity to wells was a surrogate to human presence and pastoral activity influences and appeared to affect houbara bustard distribution. The weight of human disturbance on houbara distribution is highlighted and it is recommended that this should be considered in conservation plans. [ABSTRACT FROM AUTHOR]

The article reports on the clinical and pathological features of granular cell tumor arising from the third thoracic spinal nerve root and compressing the spinal cord of a dog. Immunohistochemical studies of canine suggested a multiple embryological origin. The presence of a basal lamina and the proximity and infiltration of the spinal nerve root suggest a Schwann cell origin, but the immunophenotype of the tumor differs considerably from that of mature Schwann cell origin for the tumor.

The article presents a case study of 31-year-old man who was presented with a dramatic angioketatoma improvement with enzyme replacement therapy (ERT). He was diagnosed with Fabry disease (FD) following an ophthalmologic examination for post-traumatic ocular lesion showing bilateral cornea verticilata. The study suggests the need for dermatological lesions to be regularly monitored in FD to clinically evaluate the impact of ERT in vascular lesions of FD.

Describes the results of a study of the distribution of resistant prion protein in the brains of bovine spongiform encephalopathy (BSE)-affected cows identified by the active surveillance program in Catalonia, Spain. Performance of immunohistochemistry to detect resistant prion protein deposition and synaptic protein loss; Detection of large amounts of intraneuronal resistant prion protein deposition in the rhinencephalon; Assertion that resistant prion protein is widely distributed in the brains of BSE-positive cows showing little or no spongiform change or synaptic protein changes in the target nuclei.

The article presents information on the side effect of hydroxyurea in the patients with polycythemia rubra vera. It discusses the association ofporokeratoses with polycythemia rubra vera in the patients treated with hydroxyurea which include the development of several non melanoma skin cancers. The case of a 75-year-old Caucasian man who developed large annular plaques of the lower legs after treated with hydroxyurea is also discussed.

The characteristics and availability of the sleeping sites used by a group of 27 tufted capuchin monkeys (Cebus apella nigritus) were studied during 17 months at the Iguazu National Park, Argentina. We tested different hypotheses regarding possible ultimate causes of sleeping-site selection. Most sleeping sites were located in areas of tall, mature forest. Of the 34 sleeping sites the monkeys used during 203 nights, five were more frequently used than the others (more than 20 times each, constituting 67% of the nights). Four species of tree (Peltophorum dubium, Parapiptadenia rigida, Copaifera langsdorfii and Cordia trichotoma) were the most frequently used. They constituted 82% of all the trees used, though they represent only 12% of the trees within the monkeys' home range which had a diameter at breast height (DBH) > 48.16 cm (1 SD below the mean DBH of sleeping trees). The sleeping trees share a set of characteristics not found in other trees: they are tall emergent (mean height +/- SD = 31.1+/-5.2 m) with large DBH (78.5+/-30.3 cm), they have large crown diameter (14+/-5.5 m), and they have many horizontal branches and forks. Adult females usually slept with their kin and infants, while peripheral adult males sometimes slept alone in nearby trees. We reject parasite avoidance as an adaptive explanation for the pattern of sleeping site use. Our results and those from other studies suggest that predation avoidance is a predominant factor driving sleeping site preferences. The patterns of aggregation at night and the preference for trees with low probability of shedding branches suggest that social preferences and safety from falling during windy nights may also affect sleeping tree selection. The importance of other factors, such as seeking comfort and maintaining group cohesion, was not supported by our results. Other capuchin populations show different sleeping habits which can be explained by differences in forest structure and by demographic differences.