Coping with continuous human disturbance in the wild: insights from penguin heart rate response to various stressors.

ABSTRACT: BACKGROUND: A central question for ecologists is the extent to which anthropogenic disturbances (e.g. tourism) might impact wildlife and affect the systems under study. From a research perspective, identifying the effects of human disturbance caused by research-related activities is crucial in order to understand and account for potential biases and derive appropriate conclusions from the data. RESULTS: Here, we document a case of biological adjustment to chronic human disturbance in a colonial seabird, the king penguin (Aptenodytes patagonicus), breeding on remote and protected islands of the Southern ocean. Using heart rate (HR) as a measure of the stress response, we show that, in a colony with areas exposed to the continuous presence of humans (including scientists) for over 50 years, penguins have adjusted to human disturbance and habituated to certain, but not all, types of stressors. When compared to birds breeding in relatively undisturbed areas, birds in areas of high chronic human disturbance were found to exhibit attenuated HR responses to acute anthropogenic stressors of low-intensity (i.e. sounds or human approaches) to which they had been subjected intensely over the years. However, such attenuation was not apparent for high-intensity stressors (i.e. captures for scientific research) which only a few individuals experience each year. CONCLUSIONS: Habituation to anthropogenic sounds/approaches could be an adaptation to deal with chronic innocuous stressors, and beneficial from a research perspective. Alternately, whether penguins have actually habituated to anthropogenic disturbances over time or whether human presence has driven the directional selection of human-tolerant phenotypes, remains an open question with profound ecological and conservation implications, and emphasizes the need for more knowledge on the effects of human disturbance on long-term studied populations.

Long diagnostic delay in Crohn's disease is associated with complicated disease course and increased operation rate

Background and Aims: The impact of d iagnostic delay ( a period from appearance of f irst s ymptoms t o diagnosis) o n the clinical c ourse o f Crohn's disease (CD) i s unknown. W e examined whether length of d iagnostic delay a ffects d isease outcome. Methods: Data from the Swiss IBD cohort study were analyzed. T he frequencies of o ccurrence of b owel s tenoses, internal fistulas, perianal f istulas, and CD-related surgery at distinct i ntervals a fter C D diagnosis (0 - < 2 , 2 - < 6,  6 years) were c ompared f or g roups o f patients w ith different length of d iagnostic delay. Results: T he data from a g roup o f 200 CD patients with long diagnostic delay (> 24 months, 76th - 100th p ercentile) were c ompared to t hose from a group of 4 61 patients with a short diagnostic delay ( within 9 months, 1st - 50th p ercentile). T reatment r egimens d id n ot d iffer between t he two groups. Two years following diagnosis, p atients with long diagnostic delay presented more frequently with bowel stenoses (25% vs. 13.1%, p = 0.044), internal fistulas (10% vs. 2%, p = 0.018), perianal f istulas ( 20% vs. 8 .1%, p = 0.023) a nd more frequently underwent intestinal surgery (15% vs. 5 .1%, p = 0.024) t han patients with short diagnostic delay. Intestinal surgery was a lso m ore frequently p erformed  6 y ears after diagnosis in t he group with long d iagnostic delay ( 56.2% vs. 42.3%, p = 0.005) w hen compared to t he g roup with short diagnostic delay. Conclusions: L ong diagnostic delay i s associated with worse o utcome c haracterized by t he development o f increased bowel damage, n ecessitating more frequently operations in t he years following CD d iagnosis. Efforts should be undertaken to shorten the diagnostic delay.

Impact of bulk cardiac motion on right coronary MR angiography and vessel wall imaging.

The purpose of this study was to investigate the impact of in-plane coronary artery motion on coronary magnetic resonance angiography (MRA) and coronary MR vessel wall imaging. Free-breathing, navigator-gated, 3D-segmented k-space turbo field echo ((TFE)/echo-planar imaging (EPI)) coronary MRA and 2D fast spin-echo coronary vessel wall imaging of the right coronary artery (RCA) were performed in 15 healthy adult subjects. Images were acquired at two different diastolic time periods in each subject: 1) during a subject-specific diastasis period (in-plane velocity <4 cm/second) identified from analysis of in-plane coronary artery motion, and 2) using a diastolic trigger delay based on a previously implemented heart-rate-dependent empirical formula. RCA vessel wall imaging was only feasible with subject-specific middiastolic acquisition, while the coronary wall could not be identified with the heart-rate-dependent formula. For coronary MRA, RCA border definition was improved by 13% (P < 0.001) with the use of subject-specific trigger delay (vs. heart-rate-dependent delay). Subject-specific middiastolic image acquisition improves 3D TFE/EPI coronary MRA, and is critical for RCA vessel wall imaging.

Is it appropriate to index glomerular filtration rate for body surface area

Purpose: Obesity is an established independent risk factor for chronic kidney disease. Thus, measurement of glomerular filtration rate (GFR) is important in this population. Traditionally, GFR has been indexed for body surface area (BSA), but this indexation may not be appropriate in obese individuals. Therefore, the objective of the study was to compare absolute GFR with GFR indexed for BSA and with GFR indexed for height. Methods and materials: The study was conducted in 66 families from the Seychelles islands that included several members with hypertension. GFR and effective renal plasma flow (ERPF) were measured using inulin and PAH clearances, respectively. Antihypertensive treatment, if used, was withheld 2 weeks before conducting the clearances. Participants with diabetes mellitus were excluded from the analysis. BSA was calculated using the Dubois formula. We assessed trend across BMI categories using a non parametric test. Results: Participants included 174 women and 127 men. The prevalence of hypertension was 61%, of which 68% were treated. The table shows that absolute GFR, GFR indexed for height, ERPF, filtration fraction were significantly higher across BMI categories. When GFR was indexed for BSA, the association between GFR and BMI categories was lost. Conclusion: Indexing GFR for BSA in overweight and obese individuals leads to a substantial underestimation of GFR. Filtration fraction, which does not depend on BSA, is higher in obese individuals, which suggests glomerular hyperfiltration. Indexing GFR for BSA therefore would mask the underlying glomerular hyperfiltration. As the number of nephrons does not increase with weight gain, absolute GFR represents a better marker of single nephron GFR and is more appropriate.

The QUASAR reproducibility study, Part II: Results from a multi-center Arterial Spin Labeling test-retest study.

Arterial Spin Labeling (ASL) is a method to measure perfusion using magnetically labeled blood water as an endogenous tracer. Being fully non-invasive, this technique is attractive for longitudinal studies of cerebral blood flow in healthy and diseased individuals, or as a surrogate marker of metabolism. So far, ASL has been restricted mostly to specialist centers due to a generally low SNR of the method and potential issues with user-dependent analysis needed to obtain quantitative measurement of cerebral blood flow (CBF). Here, we evaluated a particular implementation of ASL (called Quantitative STAR labeling of Arterial Regions or QUASAR), a method providing user independent quantification of CBF in a large test-retest study across sites from around the world, dubbed "The QUASAR reproducibility study". Altogether, 28 sites located in Asia, Europe and North America participated and a total of 284 healthy volunteers were scanned. Minimal operator dependence was assured by using an automatic planning tool and its accuracy and potential usefulness in multi-center trials was evaluated as well. Accurate repositioning between sessions was achieved with the automatic planning tool showing mean displacements of 1.87+/-0.95 mm and rotations of 1.56+/-0.66 degrees . Mean gray matter CBF was 47.4+/-7.5 [ml/100 g/min] with a between-subject standard variation SD(b)=5.5 [ml/100 g/min] and a within-subject standard deviation SD(w)=4.7 [ml/100 g/min]. The corresponding repeatability was 13.0 [ml/100 g/min] and was found to be within the range of previous studies.

Estimation of a maximum Lu diffusion rate in a natural eclogite garnet

Lutetium zoning in garnet within eclogites from the Zermatt-Saas Fee zone, Western Alps, reveal sharp, exponentially decreasing central peaks. They can be used to constrain maximum Lu volume diffusion in garnets. A prograde garnet growth temperature interval of 450-600 A degrees C has been estimated based on pseudosection calculations and garnet-clinopyroxene thermometry. The maximum pre-exponential diffusion coefficient which fits the measured central peak is in the order of D-0= 5.7*10(-6) m(2)/s, taking an estimated activation energy of 270 kJ/mol based on diffusion experiments for other rare earth elements in garnet. This corresponds to a maximum diffusion rate of D (600 A degrees C) = 4.0*10(-22) m(2)/s. The diffusion estimate of Lu can be used to estimate the minimum closure temperature, T-c, for Sm-Nd and Lu-Hf age data that have been obtained in eclogites of the Western Alps, postulating, based on a literature review, that D (Hf) < D (Nd) < D (Sm) a parts per thousand currency sign D (Lu). T-c calculations, using the Dodson equation, yielded minimum closure temperatures of about 630 A degrees C, assuming a rapid initial exhumation rate of 50A degrees/m.y., and an average crystal size of garnets (r = 1 mm). This suggests that Sm/Nd and Lu/Hf isochron age differences in eclogites from the Western Alps, where peak temperatures did rarely exceed 600 A degrees C must be interpreted in terms of prograde metamorphism.

The effect of obesity, age, puberty and gender on resting metabolic rate in children and adolescents.

During puberty fat-free mass (FFM) and fat mass (FM) change quickly and these changes are influenced by sex and obesity. Since it is not completely known how these changes affect resting metabolic rate (RMR), the aim of the present study was to investigate the effect of body composition, age, sex and pubertal development of postabsorptive RMR in 9.5- to 16.5- year-old obese and non-obese children. Postabsorptive RMR was measured in a sample of 371 pre- and postpubertal children comprising 193 males (116 non-obese and 77 obese) and 178 females (119 non-obese and 59 obese). RMR was assessed by indirect calorimetry using a ventilated hood system for 45 min after an overnight fast. Body composition (FFM and FM) was estimated from skinfold measurements. The mean (+/- SD) RMR was significantly (P < 0.001) lower in non-obese (males: 5600 +/- 972 kJ/24 h; females: 5112 +/- 632 kJ/24 h) than in obese (males: 7223 +/- 1220 kJ/24 h; females: 6665 +/- 1106 kJ/24 h) children. This difference became non-significant when RMR was adjusted for body composition (FFM+FM). However, the difference between the genders still remained significant (control male: 6118 +/- 507, control female: 5652 +/- 507, P < 0.001; obese male: 6256 +/- 507, obese female: 5818 +/- 507 kJ/24 h, P < 0.001). The main determinant of RMR was FFM. In the whole cohort. FFM explained 79.8% of the variation in RMR, followed by age, gender and FM adding further 3.8%, 1.1% and 0.8% to the predictability of RMR, respectively. No significant contribution for study group (obese, non-obese), pubertal stage, or fat distribution was found in the regression for RMR. The adjusted value of RMR (for FFM and FM) slightly, but significantly (P < 0.01) decreased between the age of 10-16 years, demonstrating the important effect of age on RMR. CONCLUSIONS: The resting metabolic rate of obese and control children is not different when adjusted for body composition. The main determinant of RMR is the fat-free mass, however, age, gender and fat mass are also significant factors. Pubertal development and fat distribution do not influence RMR independently from the changes in body composition.

A new spin on a compositionalist predictive modelling framework for conservation planning: a tropical case study in Ecuador

Knowledge about spatial biodiversity patterns is a basic criterion for reserve network design. Although herbarium collections hold large quantities of information, the data are often scattered and cannot supply complete spatial coverage. Alternatively, herbarium data can be used to fit species distribution models and their predictions can be used to provide complete spatial coverage and derive species richness maps. Here, we build on previous effort to propose an improved compositionalist framework for using species distribution models to better inform conservation management. We illustrate the approach with models fitted with six different methods and combined using an ensemble approach for 408 plant species in a tropical and megadiverse country (Ecuador). As a complementary view to the traditional richness hotspots methodology, consisting of a simple stacking of species distribution maps, the compositionalist modelling approach used here combines separate predictions for different pools of species to identify areas of alternative suitability for conservation. Our results show that the compositionalist approach better captures the established protected areas than the traditional richness hotspots strategies and allows the identification of areas in Ecuador that would optimally complement the current protection network. Further studies should aim at refining the approach with more groups and additional species information.

Combined effect of 25-OH vitamin D plasma levels and genetic vitamin D receptor (NR 1I1) variants on fibrosis progression rate in HCV patients.

BACKGROUND: Decreased vitamin D levels have been described in various forms of chronic liver disease and associated with advanced fibrosis. Whether this association is a cause or consequence of advanced fibrosis remains unclear to date. AIMS: To analyse combined effects of 25-OH vitamin D plasma levels and vitamin D receptor gene (VDR; NR1I1) polymorphisms on fibrosis progression rate in HCV patients. METHODS: 251 HCV patients underwent VDR genotyping (bat-haplotype: BsmI rs1544410 C, ApaI rs7975232 A and TaqI rs731236 A). Plasma 25-OH vitamin D levels were quantified in a subgroup of 97 patients without advanced fibrosis. The VDR haplotype and genotypes as well as plasma 25-OH vitamin D levels were associated with fibrosis progression. RESULTS: The bAt[CCA]-haplotype was significantly associated with fibrosis progression >0.101 U/year (P = 0.007; OR = 2.02) and with cirrhosis (P = 0.022; OR = 1.84). Forty-five percent of bAt[CCA]-haplotype patients were rapid fibrosers, 21.1% were cirrhotic. Likewise, ApaI rs7975232 CC genotype was significantly associated with fibrosis progression and cirrhosis. Lower plasma 25-OH vitamin D levels were significantly associated with fibrosis progression >0.101 U/year in F0-2 patients (P = 0.013). Combined analysis of both variables revealed a highly significant additive effect on fibrosis progression with 45.5% rapid fibrosers for bAt[CCA]-haplotype and 25-OH vitamin D < 20 μg/L compared with only 9.1% for the most favourable combination (P = 0.006). In multivariate analysis, the bAt-haplotype was an independent risk factor for fibrosis progression (P = 0.001; OR = 2.83). CONCLUSION: Low 25-OH vitamin D plasma levels and the unfavourable VDR bAt[CCA]-haplotype are associated with rapid fibrosis progression in chronic HCV patients. In combination, both variables exert significant additive effects on fibrosis progression.

Rate of undesirable events at beginning of academic year: retrospective cohort study.

OBJECTIVE: To determine whether an increase in the rate of undesirable events occurs after care provided by trainees at the beginning of the academic year. DESIGN: Retrospective cohort study using administrative and patient record data. SETTING: University affiliated hospital in Melbourne, Australia. PARTICIPANTS: 19,560 patients having an anaesthetic procedure carried out by first to fifth year trainees starting work for the first time at the hospital over a period of five years (1995-2000). MAIN OUTCOME MEASURES: Absolute event rates, absolute rate reduction, and rate ratios of undesirable events. RESULTS: The rate of undesirable events was higher at the beginning of the academic year compared with the rest of the year (absolute event rate 137 v 107 per 1000 patient hours, relative rate reduction 28%, P<0.001). The overall adjusted rate ratio for undesirable events was 1.40, 95% confidence interval 1.24 to 1.58. This excess risk was seen for all residents, regardless of their level of seniority. The excess risk decreased progressively after the first month, and the trend disappeared fully after the fourth month of the year (rate ratio for fourth month 1.21, 0.93 to 1.57). The most important decreases were for central and peripheral nerve injuries (relative difference 82%), inadequate oxygenation of the patient (66%), vomiting/aspiration in theatre (53%), and technical failures of tracheal tube placement (49%). CONCLUSIONS: The rate of undesirable events was greater among trainees at the beginning of the academic year regardless of their level of clinical experience. This suggests that several additional factors, such as knowledge of the working environment, teamwork, and communication, may contribute to the increase.

The effect of workplace smoking bans on heart rate variability and pulse wave velocity of non-smoking hospitality workers

OBJECTIVES: To investigate the effect of a change in second-hand smoke (SHS) exposure on heart rate variability (HRV) and pulse wave velocity (PWV), this study utilized a quasi-experimental setting when a smoking ban was introduced. METHODS: HRV, a quantitative marker of autonomic activity of the nervous system, and PWV, a marker of arterial stiffness, were measured in 55 non-smoking hospitality workers before and 3-12 months after a smoking ban and compared to a control group that did not experience an exposure change. SHS exposure was determined with a nicotine-specific badge and expressed as inhaled cigarette equivalents per day (CE/d). RESULTS: PWV and HRV parameters significantly changed in a dose-dependent manner in the intervention group as compared to the control group. A one CE/d decrease was associated with a 2.3 % (95 % CI 0.2-4.4; p = 0.031) higher root mean square of successive differences (RMSSD), a 5.7 % (95 % CI 0.9-10.2; p = 0.02) higher high-frequency component and a 0.72 % (95 % CI 0.40-1.05; p < 0.001) lower PWV. CONCLUSIONS: PWV and HRV significantly improved after introducing smoke-free workplaces indicating a decreased cardiovascular risk.

Human papilloma virus type and recurrence rate after surgical clearance of anal condylomata acuminata

Résumé : Le condylome acuminé anal (CAA), transmis par contact sexuel, résulte d'une infection par Human Papilloma Virus (HPV). Son traitement chirurgical est grevé d'un taux de récidive de 4-29%. Le but de cette étude était d'identifier une éventuelle corrélation entre type d'HPV présent dans les CAA excisés chirurgicalement et taux de récidive de la maladie, Cette étude rétrospective porte sur 140 patients opérés au Centre Hospitalier Universitaire Vaudois de CAA, entre 1990 et 2005. Le diagnostic lésionnel a été confirmé par un examen histomorphologique. Le(s) type(s) d'HPV présent(s) dans ces lésions a été déterminé par Polymerase Chain Reaction (PCR). Les patients ont donné leur accord à cette analyse et complété un questionnaire. Une éventuelle corrélation entre récidive de CAA, type d'HPV et status HIV a été recherchée. HPV 6 et 11 sont les virus les plus fréquemment découverts (51% et 28%, respectivement) chez les 140 patients (123H/17F). Trente-cinq (25%) d'entre eux ont présenté une récidive. HPV 11 était present chez 19 (41%) sujets. Ceci est statistiquement significatif (P<0.05), en comparaison aux autres HPVs. Il n'y a par contre pas de différence significative entre la fréquence de récidive des 33 (24%) patients HIV-positifs et le reste du collectif. HPV 11 est donc associé à un taux de récidive de CAA significativement élevé. Un suivi strict des patients atteints est nécessaire pour identifier une récidive et la traiter sans délai, notamment lorsque HPV 11 est present. Ces résultats innovateurs soulèvent la question de la nécessité de pratiquer une typisation virale systématique sur les lésions excisées. La justification d'une telle attitude demande toutefois encore d'être confirmée.

Local re-inversion coronary MR angiography: arterial spin-labeling without the need for subtraction.

PURPOSE: To implement a double-inversion bright-blood coronary MR angiography sequence using a cylindrical re-inversion prepulse for selective visualization of the coronary arteries. MATERIALS AND METHODS: Local re-inversion bright-blood magnetization preparation was implemented using a nonselective inversion followed by a cylindrical aortic re-inversion prepulse. After an inversion delay that allows for in-flow of the labeled blood-pool into the coronary arteries, three-dimensional radial steady-state free-precession (SSFP) imaging (repetition/echo time, 7.2/3.6 ms; flip angle, 120 degrees, 16 profiles per RR interval; field of view, 360 mm; matrix, 512, twelve 3-mm slices) is performed. Coronary MR angiography was performed in three healthy volunteers and in one patient on a commercial 1.5 Tesla whole-body MR System. RESULTS: In all subjects, coronary arteries were selectively visualized with positive contrast. In addition, a middle-grade stenosis of the proximal right coronary artery was seen in one patient. CONCLUSION: A novel T1 contrast-enhancement strategy is presented for selective visualization of the coronary arteries without extrinsic contrast medium application. In comparison to former arterial spin-labeling schemes, the proposed magnetization preparation obviates the need for a second data set and subtraction.