Publications by authors named "Elke Zimmermann"

122 Publications

Detection of relevant extracardiac findings on coronary computed tomography angiography vs. invasive coronary angiography.

Eur Radiol 2021 Jun 15. Epub 2021 Jun 15.

Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.

Objectives: To compare the detection of relevant extracardiac findings (ECFs) on coronary computed tomography angiography (CTA) and invasive coronary angiography (ICA) and evaluate the potential clinical benefit of their detection.

Methods: This is the prespecified subanalysis of ECFs in patients presenting with a clinical indication for ICA based on atypical angina and suspected coronary artery disease (CAD) included in the prospective single-center randomized controlled Coronary Artery Disease Management (CAD-Man) study. ECFs requiring immediate therapy and/or further workup including additional imaging were defined as clinically relevant. We evaluated the scope of ECFs in 329 patients and analyzed the potential clinical benefit of their detection.

Results: ECFs were detected in 107 of 329 patients (32.5%; CTA: 101/167, 60.5%; ICA: 6/162, 3.7%; p < .001). Fifty-nine patients had clinically relevant ECFs (17.9%; CTA: 55/167, 32.9%; ICA: 4/162, 2.5%; p < .001). In the CTA group, ECFs potentially explained atypical chest pain in 13 of 101 patients with ECFs (12.9%). After initiation of therapy, chest pain improved in 4 (4.0%) and resolved in 7 patients (6.9%). Follow-up imaging was recommended in 33 (10.0%; CTA: 30/167, 18.0%; ICA: 3/162, 1.9%) and additional clinic consultation in 26 patients (7.9%; CTA: 25/167, 15.0%; ICA: 1/162, 0.6%). Malignancy was newly diagnosed in one patient (0.3%; CTA: 1/167, 0.6%; ICA: 0).

Conclusions: In this randomized study, CTA but not ICA detected clinically relevant ECFs that may point to possible other causes of chest pain in patients without CAD. Thus, CTA might preclude the need for ICA in those patients.

Trial Registration: NCT Unique ID: 00844220 KEY POINTS: • CTA detects ten times more clinically relevant ECFs than ICA. • Actionable clinically relevant ECFs affect patient management and therapy and may thus improve chest pain. • Detection of ECFs explaining chest pain on CTA might preclude the need for performing ICA.
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http://dx.doi.org/10.1007/s00330-021-07967-xDOI Listing
June 2021

Movement analysis of primate molar teeth under load using synchrotron X-ray microtomography.

J Struct Biol 2021 03 15;213(1):107658. Epub 2020 Nov 15.

Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max-Planck-Institute for Evolutionary Anthropology, 04103 Leipzig, Germany. Electronic address:

Mammalian teeth have to sustain repetitive and high chewing loads without failure. Key to this capability is the periodontal ligament (PDL), a connective tissue containing a collagenous fibre network which connects the tooth roots to the alveolar bone socket and which allows the teeth to move when loaded. It has been suggested that rodent molars under load experience a screw-like downward motion but it remains unclear whether this movement also occurs in primates. Here we use synchroton micro-computed tomography paired with an axial loading setup to investigate the form-function relationship between tooth movement and the morphology of the PDL space in a non-human primate, the mouse lemur (Microcebus murinus). The loading behavior of both mandibular and maxillary molars showed a three-dimensional movement with translational and rotational components, which pushes the tooth into the alveolar socket. Moreover, we found a non-uniform PDL thickness distribution and a gradual increase in volumetric proportion of the periodontal vasculature from cervical to apical. Our results suggest that the PDL morphology may optimize the three-dimensional tooth movement to avoid high stresses under loading.
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http://dx.doi.org/10.1016/j.jsb.2020.107658DOI Listing
March 2021

Computed tomography for detection of septic foci: Retrospective analysis of patients presenting to the emergency department.

Clin Imaging 2021 Jan 19;69:223-227. Epub 2020 Sep 19.

Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Luisenstraße 7, 10117 Berlin, Germany.

Objective: Sepsis is defined as organ dysfunction due to severe infection. Septic patients face a significant mortality risk. Thus, timely recognition with prompt focus identification and control are essential. This study aims to determine the current role of computed tomography (CT) in the diagnostic workup of septic patients.

Methods: We retrospectively identified 357 patients in the emergency department (ED) of a large university center with suspected sepsis in a two-year period. A total of 132 patients underwent CT scanning within 72 h of admission. Patients were characterized by clinical and laboratory findings. CT reports were categorized and matched with clinical data.

Results: Of 357 ED patients with suspected sepsis, 37.0% (132/357) underwent CT imaging within 72 h. The most commonly identified septic foci in CT were chest 38.6% (49/127), abdomen 22.0% (28/127) and genitourinary tract 20.5% (26/127) in descending order. The focus detection rate was 76.5% per patient with a concurrent number-needed-to-scan of 1.31. Contrast medium administration in CT did not improve focus detection rate (p = 0.631) or diagnostic confidence in this patient population (p = 0.432). CT had a positive predictive value of 81.82% (CI 76.31 to 86.28%) in predicting the focus of the discharge diagnosis. Follow-up imaging in patients with unclear focus reveals a new focus in 39.5% of patients.

Conclusions: Our investigation of the role of CT in ED patients with suspected sepsis indicated a high positive predictive value for CT with regard to the discharge diagnosis. Repeat imaging may help identify further septic foci in a subgroup with persistently unclear focus. Use of contrast medium seems less relevant for focus detection than expected, as it did not increase diagnostic confidence.
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http://dx.doi.org/10.1016/j.clinimag.2020.09.004DOI Listing
January 2021

Neurobiological substrates of animal personality and cognition in a nonhuman primate (Microcebus murinus).

Brain Behav 2020 09 18;10(9):e01752. Epub 2020 Jul 18.

Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.

Introduction: The gray mouse lemur (Microcebus murinus) is an important nonhuman primate model in biomedical research. Numerous studies investigated mouse lemur behavior and possible factors underlying interindividual variation in both, animal personality and cognitive performance. Some effects, such as an age-related decline in executive functioning, have robustly been found across laboratory colonies; however, little is known about the brain structural substrates in mouse lemurs.

Methods: Here, we provide first exploratory data linking in vivo magnetic resonance imaging of 34 mouse lemurs to performance in a standardized, touchscreen-based task on object discrimination and reversal learning as well as to animal personality under different scenarios in an open field.

Results: High interindividual variability in both brain morphometric and behavioral measurements was found, but only few significant correlations between brain structure and behavior were revealed: Object discrimination learning was linked to the volume of the hippocampus and to temporal lobe thickness, while reversal learning was linked to thalamic volume and the thickness of the anterior cingulate lobe. Emergence latency into the open field correlated with volume of the amygdala. General exploration-avoidance in the empty open-field arena correlated with thicknesses of the anterior cingulate lobe and fronto-parietal substructures. Neophilia, assessed as exploration of a novel object placed in the arena, among others, related to the volume of the caudate nucleus.

Conclusion: In summary, our data suggest a prominent role of temporal structures (including the hippocampus) for learning capability, as well as thalamic and anterior cingulate structures for cognitive flexibility and response inhibition. The amygdala, the anterior cingulate lobe, and the caudate nucleus are particularly linked to animal personality in the open-field setting. These findings are congruent with the comparative psychological literature and provide a valuable basis for future studies elucidating aspects of behavioral variation in this nonhuman primate model.
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http://dx.doi.org/10.1002/brb3.1752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7507526PMC
September 2020

Linking cognition to age and amyloid-β burden in the brain of a nonhuman primate (Microcebus murinus).

Neurobiol Aging 2020 10 14;94:207-216. Epub 2020 Jun 14.

MMDN, University of Montpellier, EPHE, INSERM, U1198, PSL University, Montpellier, France.

The gray mouse lemur (Microcebus murinus) is a valuable model in research on age-related proteopathies. This nonhuman primate, comparable to humans, naturally develops tau and amyloid-β proteopathies during aging. Whether these are linked to cognitive alterations is unknown. Here, standardized cognitive testing in pairwise discrimination and reversal learning in a sample of 37 aged (>5 years) subjects was combined with tau and amyloid-β histochemistry in individuals that died naturally. Correlation analyses in successfully tested subjects (n = 22) revealed a significant relation between object discrimination learning and age, strongly influenced by outliers, suggesting pathological cases. Where neuroimmunohistochemistry was possible, as subjects deceased, the naturally developed cortical amyloid-β burden was significantly linked to pretraining success (intraneuronal accumulations) and discrimination learning (extracellular deposits), showing that cognitive (pairwise discrimination) performance in old age predicts the natural accumulation of amyloid-β at death. This is the first description of a direct relation between the cortical amyloid-β burden and cognition in a nonhuman primate.
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http://dx.doi.org/10.1016/j.neurobiolaging.2020.03.025DOI Listing
October 2020

Effectiveness of the clinical decision support tool ESR eGUIDE for teaching medical students the appropriate selection of imaging tests: randomized cross-over evaluation.

Eur Radiol 2020 Oct 20;30(10):5684-5689. Epub 2020 May 20.

Department of Radiology, Charité - Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Freie Universitat Berlin, Charitéplatz 1, 10117, Berlin, Germany.

Objectives: To evaluate ESR eGUIDE-the European Society of Radiology (ESR) e-Learning tool for appropriate use of diagnostic imaging modalities-for learning purposes in different clinical scenarios.

Methods: This anonymized evaluation was performed after approval of ESR Education on Demand leadership. Forty clinical scenarios were developed in which at least one imaging modality was clinically most appropriate, and the scenarios were divided into sets 1 and 2. These sets were provided to medical students randomly assigned to group A or B to select the most appropriate imaging test for each scenario. Statistical comparisons were made within and across groups.

Results: Overall, 40 medical students participated, and 31 medical students (78%) answered both sets. The number of correctly chosen imaging methods per set in these 31 paired samples was significantly higher when answered with versus without use of ESR eGUIDE (13.7 ± 2.6 questions vs. 12.1 ± 3.2, p = 0.012). Among the students in group A, who first answered set 1 without ESR eGUIDE (11.1 ± 3.2), there was significant improvement when set 2 was answered with ESR eGUIDE (14.3 ± 2.5, p = 0.013). The number of correct answers in group B did not drop when set 2 was answered without ESR eGUIDE (12.4 ± 2.6) after having answered set 1 first with ESR eGUIDE (13.0 ± 2.7, p = 0.66).

Conclusion: The clinical decision support tool ESR eGUIDE is suitable for training medical students in choosing the best radiological imaging modality in typical scenarios, and its use in teaching radiology can thus be recommended.

Key Points: • ESR eGUIDE improved the number of appropriately selected imaging modalities among medical students. • This improvement was also seen in the group of students which first selected imaging tests without ESR eGUIDE. • In the student group which used ESR eGUIDE first, appropriate selection remained stable even without the teaching tool.
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http://dx.doi.org/10.1007/s00330-020-06942-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7476994PMC
October 2020

Comparative effectiveness of coronary artery stenosis and atherosclerotic plaque burden assessment for predicting 30-day revascularization and 2-year major adverse cardiac events.

Int J Cardiovasc Imaging 2020 Dec 2;36(12):2365-2375. Epub 2020 May 2.

Department of Medicine, Johns Hopkins University, Baltimore, USA.

Purpose: To provide comparative prognostic information of coronary atherosclerotic plaque volume and stenosis assessment in patients with suspected coronary artery disease (CAD).

Methods: We followed 372 patients with suspected or known CAD enrolled in the CORE320 study for 2 years after baseline 320-detector row cardiac CT scanning and invasive quantitative coronary angiography (QCA). CT images were analyzed for coronary calcium scanning (CACS), semi-automatically derived total percent atheroma volume (PAV), segment stenosis score (SSS), in addition to traditional stenosis assessment (≥ 50%) by CT and QCA for (1) 30-day revascularization and (2) major adverse cardiac events (MACE). Area under the receiver operating characteristic curve (AUC) was used to compare accuracy of risk prediction.

Results: Sixty percent of patients had obstructive CAD by QCA with 23% undergoing 30-day revascularization and 9% experiencing MACE at 2 years. Most late events (20/32) were revascularization procedures. Prediction of 30-day revascularization was modest (AUC range 0.67-0.78) but improved after excluding patients with known CAD (AUC range 0.73-0.86, p < 0.05 for all). Similarly, prediction of MACE improved after excluding patients with known CAD (AUC range 0.58-0.73 vs. 0.63-0.77). CT metrics of atherosclerosis burden performed overall similarly but stenosis assessment was superior for predicting 30-day revascularization.

Conclusions: Angiographic and coronary atherosclerotic plaque metrics perform only modestly well for predicting 30-day revascularization and 2-year MACE in high risk patients but improve after excluding patients with known CAD. Atherosclerotic plaque metrics did not yield incremental value over stenosis assessment for predicting events that predominantly consisted of revascularization procedures.

Clinical Trial Registration: NCT00934037.
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http://dx.doi.org/10.1007/s10554-020-01851-3DOI Listing
December 2020

Evolutionary significance of the variation in acoustic communication of a cryptic nocturnal primate radiation ( spp.).

Ecol Evol 2020 Apr 12;10(8):3784-3797. Epub 2020 Mar 12.

Institute of Zoology University of Veterinary Medicine Hannover Hannover Germany.

Acoustic phenotypic variation is of major importance for speciation and the evolution of species diversity. Whereas selective and stochastic forces shaping the acoustic divergence of signaling systems are well studied in insects, frogs, and birds, knowledge on the processes driving acoustic phenotypic evolution in mammals is limited. We quantified the acoustic variation of a call type exchanged during agonistic encounters across eight distinct species of the smallest-bodied nocturnal primate radiation, the Malagasy mouse lemurs. The species live in two different habitats (dry forest vs. humid forest), differ in geographic distance to each other, and belong to four distinct phylogenetic clades within the genus. Genetically defined species were discriminated reliably on the phenotypic level based on their acoustic distinctiveness in a discriminant function analysis. Acoustic variation was explained by genetic distance, whereas differences in morphology, forest type, or geographic distance had no effect. The strong impact of genetics was supported by a correlation between acoustic and genetic distance and the high agreement in branching pattern between the acoustic and molecular phylogenetic trees. In sum, stochastic factors such as genetic drift best explained acoustic diversification in a social communication call of mouse lemurs.
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http://dx.doi.org/10.1002/ece3.6177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7160168PMC
April 2020

Dispersal and genetic structure in a tropical small mammal, the Bornean tree shrew (Tupaia longipes), in a fragmented landscape along the Kinabatangan River, Sabah, Malaysia.

BMC Genet 2020 04 17;21(1):43. Epub 2020 Apr 17.

University of Veterinary Medicine Hannover, Institute of Zoology, Buenteweg 17, 30559, Hannover, Germany.

Background: Constraints in migratory capabilities, such as the disruption of gene flow and genetic connectivity caused by habitat fragmentation, are known to affect genetic diversity and the long-term persistence of populations. Although negative population trends due to ongoing forest loss are widespread, the consequence of habitat fragmentation on genetic diversity, gene flow and genetic structure has rarely been investigated in Bornean small mammals. To fill this gap in knowledge, we used nuclear and mitochondrial DNA markers to assess genetic diversity, gene flow and the genetic structure in the Bornean tree shrew, Tupaia longipes, that inhabits forest fragments of the Lower Kinabatangan Wildlife Sanctuary, Sabah. Furthermore, we used these markers to assess dispersal regimes in male and female T. longipes.

Results: In addition to the Kinabatangan River, a known barrier for dispersal in tree shrews, the heterogeneous landscape along the riverbanks affected the genetic structure in this species. Specifically, while in larger connected forest fragments along the northern riverbank genetic connectivity was relatively undisturbed, patterns of genetic differentiation and the distribution of mitochondrial haplotypes in a local scale indicated reduced migration on the strongly fragmented southern riverside. Especially, oil palm plantations seem to negatively affect dispersal in T. longipes. Clear sex-biased dispersal was not detected based on relatedness, assignment tests, and haplotype diversity.

Conclusion: This study revealed the importance of landscape connectivity to maintain migration and gene flow between fragmented populations, and to ensure the long-term persistence of species in anthropogenically disturbed landscapes.
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http://dx.doi.org/10.1186/s12863-020-00849-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164274PMC
April 2020

Sex-specific patterns of age-related cerebral atrophy in a nonhuman primate Microcebus murinus.

Neurobiol Aging 2020 07 4;91:148-159. Epub 2020 Mar 4.

Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.

Steadily aging populations result in a growing need for research regarding age-related brain alterations and neurodegenerative pathologies. By allowing a good translation of results to humans, nonhuman primates, such as the gray mouse lemur Microcebus murinus, have gained attention in this field. Our aim was to examine correlations between atrophy-induced brain alterations and age, with special focus on sex differences in mouse lemurs. For cerebral volumetric measurements, in vivo magnetic resonance imaging was performed on 59 animals (28♀♀/31♂♂) aged between 1.0 to 11.9 years. Volumes of different brain regions, cortical thicknesses, and ventricular expansions were evaluated. Analyses revealed significant brain atrophies with increasing age, particularly around the caudate nucleus, the thalamus, and frontal, parietal, and temporo-occipital regions. Especially old females showed a strong decline in cingulate cortex thickness and had higher values of ventricular expansion, whereas cortical thickness of the splenium and occipital regions decreased mainly in males. Our study, thus, provides first evidence for sex-specific, age-related brain alterations in a nonhuman primate, suggesting that mouse lemurs can help elucidating the mechanism underlying sex disparities in cerebral aging, for which there is mixed evidence in humans.
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http://dx.doi.org/10.1016/j.neurobiolaging.2020.02.027DOI Listing
July 2020

First experimental evidence for olfactory species discrimination in two nocturnal primate species (Microcebus lehilahytsara and M. murinus).

Sci Rep 2019 12 31;9(1):20386. Epub 2019 Dec 31.

Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.

Olfactory communication is highly important for nocturnal mammals, especially for solitary foragers, but knowledge is still limited for nocturnal primates. Mouse lemurs (Microcebus spp.) are nocturnal solitary foragers with a dispersed lifestyle and frequently use chemo-sensory signalling behaviour for governing social interactions. Different mouse lemur species can co-occur in a given forest but it is unknown whether olfaction is involved in species recognition. We first screened 24 captive mouse lemurs (9 M. murinus, 15 M. lehilahytsara) for their olfactory learning potential in an experimental arena and then tested the species discrimination ability with urine odour in an operant conditioning paradigm in four individuals. The majority of the screened animals (75%) did not pass the screening criteria within a 2-week test period. However, all four final test animals, two M. murinus and two M. lehilahytsara, were successfully trained in a 5-step-conditioning process to reliably discriminate conspecific from heterospecific urine odour (requiring an overall median of 293 trials). Findings complement previous studies on the role of acoustic signalling and suggest that olfaction may be an important additional mechanism for species discrimination.
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http://dx.doi.org/10.1038/s41598-019-56893-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6938479PMC
December 2019

An empirical estimate of the generation time of mouse lemurs.

Am J Primatol 2019 12 20;81(12):e23062. Epub 2019 Oct 20.

Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.

The generation time of organisms drives the rate of change in populations and across evolutionary times. In long-lived species, generation time should also account for overlapping generations, and the average age of parents has been proposed as a best approximation under these conditions. This study uses this definition to estimate the generation time of a widely studied small primate, Microcebus murinus, based on parentage data generated for a free-living population over a 6-year period in northwestern Madagascar. The average age of parents was calculated separately for mothers and fathers of three different offspring cohorts that differed in the degree of demographic uncertainty. In addition, adult survival rates were calculated for males and females based on long-term capture data from the same population to estimate the possible upper limits of generation time. Adult survival was low with only 44% of adult females and 38% of adult males being recaptured at the beginning of their second breeding season. The average age of mothers was 1.56-1.91 years, pointing toward a 2-year female generation time due to the high proportion of 1-year old mothers in all three cohorts. Female generation time estimates were fairly stable across the three offspring cohorts. In contrast, the average age of fathers differed by more than 1 year from the first to the third offspring cohort (1.71-2.83 years) pointing toward a 3-year generation time, but also suggesting a higher degree of demographic uncertainty in the early years of the study. For future modeling purposes, we, therefore, propose to use the average, 2.5 years, of male and female values as new estimate for the generation time of mouse lemurs.
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http://dx.doi.org/10.1002/ajp.23062DOI Listing
December 2019

A new species of Schoutedenichia Jadin & Vercammen-Grandjean, 1954 from Madagascar and a re-description of S. dutoiti (Radford, 1948) from South Africa (Acariformes: Trombiculidae).

Syst Parasitol 2019 11 26;96(8):703-713. Epub 2019 Aug 26.

Department of Biology, Georgia Southern University, Statesboro, GA, 30458, USA.

A new chigger mite species, Schoutedenichia microcebi n. sp. is described from the grey mouse lemur Microcebus murinus (J.F. Miller) from Madagascar. The new species is closely related to S. dutoiti (Radford, 1948), a species described from a single specimen collected on a rodent in South Africa. Examination of the holotype and new material on S. dutoiti from South Africa enabled us to re-describe this species and provide new data on its hosts and geographical distribution.
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http://dx.doi.org/10.1007/s11230-019-09877-5DOI Listing
November 2019

Differences in infection patterns of vector-borne blood-stage parasites of sympatric Malagasy primate species (, ).

Int J Parasitol Parasites Wildl 2019 Dec 7;10:59-70. Epub 2019 Jul 7.

Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany.

The dynamic relationship of vector-borne parasites, arthropod vectors and their hosts is prone to change under the influence of climate change, global integration, shifting demographics and deforestation. It is therefore essential to better understand parasitism in wildlife populations, including parasites transmitted by blood-feeding vectors, and explore host range and heterogeneity of parasitic infections. We investigated Giemsa stained blood smears of two sympatric Malagasy primate species (: 184 samples from 69 individuals and : 264 samples from 91 individuals) for blood-stage parasites and tested for a potential influence of host species, sex, body mass and sampling month on blood-stage parasite prevalence and infection intensity. No protozoan parasites were detected in either host species. A host-specific difference was observed in filarial nematode infections, with higher risk of infection in (prevalence 30.43%), than in (prevalence 6.59%), which may be explained by differences in host behavior and/or immune competence, linked to the period of host-parasite coevolution. Neither sex nor sampling month influenced infection prevalence or intensity significantly. We did not observe a negative effect of microfilarial infections on host fitness when taking body mass as a proxy. Our results support the hypothesis of a long-term evolutionary adaptation of hosts and parasites, leading to persistent infection with low morbidity. Morphological and molecular analyses indicate the finding of a new species, "". Genetic analysis furthermore showed >99% sequence identity with microfilariae described from a sympatric, larger-bodied lemur species of a different genus, suggesting low host-specificity of the detected filariae and pathogen transmission across genus boundaries. Findings contribute to a more comprehensive picture of vector-borne diseases of Malagasy lemurs.
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http://dx.doi.org/10.1016/j.ijppaw.2019.07.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6657000PMC
December 2019

Kidney Injury after Intravenous versus Intra-arterial Contrast Agent in Patients Suspected of Having Coronary Artery Disease: A Randomized Trial.

Radiology 2019 09 2;292(3):664-672. Epub 2019 Jul 2.

From the Department of Radiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität and Freie Universität zu Berlin, Schumannstr 20/21, Berlin 10117, Germany (E.S., M.B., E.Z., R.T, M.L., M.D.); and Institute for Clinical Epidemiology and Applied Biometry, University of Tübingen, Tübingen, Germany (P.M.).

Background In the absence of randomized studies, it has been controversial whether the likelihood of acute kidney injury (AKI) differs between intravenous and intra-arterial contrast agent administration. Purpose To compare intravenous versus intra-arterial contrast agent administration in relationship to AKI and analyze the association between AKI and chronic kidney disease (defined as at least mildly decreased estimated glomerular filtration rates [eGFRs]). Materials and Methods This was a prospective study (: NCT00844220) that involved randomizing participants with atypical chest pain and suspected coronary artery disease (CAD) between February 2009 and August 2015 to undergo coronary CT angiography with intravenous contrast agent administration or cardiac catheterization angiography with intra-arterial contrast agent administration. This prespecified secondary analysis compared AKI (serum creatinine increase of ≥ 25% or 0.5 mg/dL after 18-24 or 46-50 hours) determined by blinded investigators using absolute differences and relative risks, including two-sided 95% confidence intervals (CIs). Results A total of 320 participants (163 [50.9%] women; mean age, 60 years ± 11) were included. Baseline eGFR did not differ between the CT angiography group (84.3 mL/min/1.73 m ± 17.2) and the catheterization group (87.1 mL/min/1.73 m ± 16.7) ( = .14). AKI occurred in nine of 161 participants in the CT angiography group (5.6%; 95% CI: 3%, 10%) and in 21 of 159 participants in the catheterization group (13.2%; 95% CI: 9%,19%) (relative risk, 2.4; 95% CI: 1.1, 5.0; = .02). Also in the subgroup of participants without obstructive CAD, in those not requiring coronary interventions, AKI was more common in the catheterization group (11.9%; 95% CI: 8%, 19%) than in the CT angiography group (4.3% [95% CI: 2%, 9%]; difference, 7.7% [95% CI: 1.3%, 14.1%]; relative risk, 2.8 [95% CI: 1.1, 7.0]; = .02). Obstructive CAD (odds ratio [OR]: 2.7 [95% CI: 1.1, 6.6]; = .02), femoral catheter access (OR: 2.5 [95% CI: 1.1, 5.6]; = .04), and cine ventriculography were associated with AKI (OR: 2.3 [95% CI: 1.0, 4.9]; = .03). In multivariable analysis, the presence of postcontrast AKI was associated with chronic kidney disease (hazard ratio: 12.4 [95% CI: 4.5, 34.6]; < .01). Conclusion Acute kidney injury was more common after cardiac catheterization than after CT angiography in this prospective randomized study of patients suspected of having coronary artery disease. © RSNA, 2019 See also the editorial by Einstein and Newhouse in this issue.
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http://dx.doi.org/10.1148/radiol.2019182220DOI Listing
September 2019

Diagnosis of obstructive coronary artery disease using computed tomography angiography in patients with stable chest pain depending on clinical probability and in clinically important subgroups: meta-analysis of individual patient data.

BMJ 2019 06 12;365:l1945. Epub 2019 Jun 12.

Department of Internal Medicine, University of Rome Tor Vergata, Rome, Italy.

Objective: To determine whether coronary computed tomography angiography (CTA) should be performed in patients with any clinical probability of coronary artery disease (CAD), and whether the diagnostic performance differs between subgroups of patients.

Design: Prospectively designed meta-analysis of individual patient data from prospective diagnostic accuracy studies.

Data Sources: Medline, Embase, and Web of Science for published studies. Unpublished studies were identified via direct contact with participating investigators.

Eligibility Criteria For Selecting Studies: Prospective diagnostic accuracy studies that compared coronary CTA with coronary angiography as the reference standard, using at least a 50% diameter reduction as a cutoff value for obstructive CAD. All patients needed to have a clinical indication for coronary angiography due to suspected CAD, and both tests had to be performed in all patients. Results had to be provided using 2×2 or 3×2 cross tabulations for the comparison of CTA with coronary angiography. Primary outcomes were the positive and negative predictive values of CTA as a function of clinical pretest probability of obstructive CAD, analysed by a generalised linear mixed model; calculations were performed including and excluding non-diagnostic CTA results. The no-treat/treat threshold model was used to determine the range of appropriate pretest probabilities for CTA. The threshold model was based on obtained post-test probabilities of less than 15% in case of negative CTA and above 50% in case of positive CTA. Sex, angina pectoris type, age, and number of computed tomography detector rows were used as clinical variables to analyse the diagnostic performance in relevant subgroups.

Results: Individual patient data from 5332 patients from 65 prospective diagnostic accuracy studies were retrieved. For a pretest probability range of 7-67%, the treat threshold of more than 50% and the no-treat threshold of less than 15% post-test probability were obtained using CTA. At a pretest probability of 7%, the positive predictive value of CTA was 50.9% (95% confidence interval 43.3% to 57.7%) and the negative predictive value of CTA was 97.8% (96.4% to 98.7%); corresponding values at a pretest probability of 67% were 82.7% (78.3% to 86.2%) and 85.0% (80.2% to 88.9%), respectively. The overall sensitivity of CTA was 95.2% (92.6% to 96.9%) and the specificity was 79.2% (74.9% to 82.9%). CTA using more than 64 detector rows was associated with a higher empirical sensitivity than CTA using up to 64 rows (93.4% 86.5%, P=0.002) and specificity (84.4% 72.6%, P<0.001). The area under the receiver-operating-characteristic curve for CTA was 0.897 (0.889 to 0.906), and the diagnostic performance of CTA was slightly lower in women than in with men (area under the curve 0.874 (0.858 to 0.890) 0.907 (0.897 to 0.916), P<0.001). The diagnostic performance of CTA was slightly lower in patients older than 75 (0.864 (0.834 to 0.894), P=0.018 all other age groups) and was not significantly influenced by angina pectoris type (typical angina 0.895 (0.873 to 0.917), atypical angina 0.898 (0.884 to 0.913), non-anginal chest pain 0.884 (0.870 to 0.899), other chest discomfort 0.915 (0.897 to 0.934)).

Conclusions: In a no-treat/treat threshold model, the diagnosis of obstructive CAD using coronary CTA in patients with stable chest pain was most accurate when the clinical pretest probability was between 7% and 67%. Performance of CTA was not influenced by the angina pectoris type and was slightly higher in men and lower in older patients.

Systematic Review Registration: PROSPERO CRD42012002780.
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http://dx.doi.org/10.1136/bmj.l1945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6561308PMC
June 2019

Sources of variation in social tolerance in mouse lemurs (Microcebus spp.).

BMC Ecol 2019 05 17;19(1):20. Epub 2019 May 17.

Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany.

Background: Social tolerance strongly influences the patterns of affiliation and aggression in animal societies. However, not much is known about the variation of social tolerance in species living in dispersed social systems that combine solitary foraging activities with the need of coordinating social interactions with conspecifics on a regular basis. This study aims to investigate the sources of variation in social tolerance within a Malagasy primate radiation with dispersed social systems, the mouse lemurs (Microcebus spp.). Six mouse lemur species were selected as model species that belong to three different taxonomic clades, live in two types of forest environments (dry and humid), and differed in this study with respect to their reproductive activity. Six male-female and six male-male dyads of each species were tested temporarily in a standardized social encounter paradigm in Madagascar to collect data on joint use of space, non-agonistic body contacts, aggression rates, the number of conflicts and the establishment of intra- and intersexual dominance.

Results: Male-female dyads of the six species differed significantly in the frequency of affiliative and agonistic behaviors. In contrast, the variations between male-male dyads could not be explained by one parameter only, but clade membership, forest type, reproductive state as well as species were all suggested to be partially influential. Only one species (Microcebus mamiratra) showed signals of unambiguous female dominance in all male-female dyads, whereas the others had no or only a few dyads with female dominance.

Conclusions: Variations in social tolerance and its consequences are most likely influenced by two factors, ecology (via forest type) and physiology (via reproductive activity), and only to a lesser extent by clade membership. The study suggests that mouse lemur females have higher aggression rates and more agonistic conflicts with males when females in the population are reproducing, at least in resource-rich humid forests. The study confirms a high degree of social plasticity between species in these small solitary foragers that supports their taxonomic distinctiveness and requires further scientific attention.
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http://dx.doi.org/10.1186/s12898-019-0236-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6525410PMC
May 2019

Noise reduction and motion elimination in low-dose 4D myocardial computed tomography perfusion (CTP): preliminary clinical evaluation of the ASTRA4D algorithm.

Eur Radiol 2019 Sep 4;29(9):4572-4582. Epub 2019 Feb 4.

Department of Radiology, Charité Medical School, Charitéplatz 1, 10117, Berlin, Germany.

Objectives: To propose and evaluate a four-dimensional (4D) algorithm for joint motion elimination and spatiotemporal noise reduction in low-dose dynamic myocardial computed tomography perfusion (CTP).

Methods: Thirty patients with suspected or confirmed coronary artery disease were prospectively included and underwent dynamic contrast-enhanced 320-row CTP. A novel deformable image registration method based on the principal component analysis (PCA) of the ante hoc temporally smoothed voxel-wise time-attenuation curves (ASTRA4D) is presented. Quantitative (standard deviation, signal-to-noise ratio (SNR), temporal variation, volumetric deformation) and qualitative (motion, contrast, contour sharpness [1, poor; 5, excellent]) measures of CTP quality were assessed for the original and motion-compensated sequences (without and with temporal filtering, PCA/ASTRA4D). Following myocardial perfusion deficit detection by two readers, diagnostic accuracy was evaluated using magnetic resonance myocardial perfusion imaging (MR-MPI) as the reference standard in 15 patients.

Results: Registration using ASTRA4D was successful in all 30 patients and resulted in comparison with the benchmark PCA in significantly (p < 0.001) reduced noise over time (- 83%, 178.5 vs 29.9) and spatially (- 34%, 21.4 vs 14.1) as well as improved SNR (+ 47%, 3.6 vs 5.3) and subjective image quality (motion, contrast, contour sharpness [+ 1.0, + 1.0, + 0.5]). ASTRA4D had significantly improved per-segment sensitivity of 91% (58/64) and similar specificity of 96% (429/446) compared with PCA (52%, 33/64; 98%, 435/446; p = 0.011) in the visual detection of perfusion deficits.

Conclusions: The ASTRA4D registration algorithm improved the spatiotemporal noise profile and CTP sequence image quality, resulting in significantly improved sensitivity of 4D CTP in the detection of myocardial ischemia.

Key Points: • ASTRA4D combines local temporal regression and deformable image registration. • Quantitative and qualitative measures of CTP quality are improved compared to PCA. • Improved spatiotemporal differentiation of ischemic regions leads to an excellent perfusion deficit concordance of ASTRA4D with MRI.
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http://dx.doi.org/10.1007/s00330-018-5899-8DOI Listing
September 2019

Spontaneous Spongiform Brainstem Degeneration in a Young Mouse Lemur () with Conspicuous Behavioral, Motor, Growth, and Ocular Pathologies.

Comp Med 2018 12 28;68(6):489-495. Epub 2018 Nov 28.

Department of Molecular and Human Genetics and Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.

Here we report a case of severe growth retardation and neurologic abnormalities in a female gray mouse lemur (), a small NHP species for which the genomic sequence recently became available. The female lemur we present here died on postnatal day 125. This lemur had impaired development of motor skills and showed severe ataxia and tremors. In addition, hearing seemed normal whereas ophthalmic examination revealed incipient bilateral cataracts, abnormal pigmentation in the lens of the left eye, and a missing optokinetic nystagmus, which indicated impaired vision. Most prominently, the lemur showed severe growth retardation. Necropsy revealed maldevelopment of the left reproductive organs and unilateral dilation of the right lateral ventricle, which was confirmed on brain MRI. Brain histology further revealed large, bilateral areas of vacuolation within the brainstem, but immunohistochemistry indicated no sign of pathologic prion protein deposition. Full genomic sequencing of the lemur revealed a probably pathologic mutation in of the LARGE gene family, which has been associated with congenital muscular dystrophies. However, potentially functional mutations in other genes were also present. The observed behavioral and motor signs in the presented animal might have been linked to spongiform degeneration and resulting brainstem dysfunction and progressive muscle weakness. The macroscopic developmental abnormalities and ophthalmic findings might be genetic in origin and linked to the mutation in .
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http://dx.doi.org/10.30802/AALAS-CM-18-000019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6310204PMC
December 2018

Effect of iterative reconstruction and temporal averaging on contour sharpness in dynamic myocardial CT perfusion: Sub-analysis of the prospective 4D CT perfusion pilot study.

PLoS One 2018 16;13(10):e0205922. Epub 2018 Oct 16.

Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.

Purpose: Myocardial computed tomography perfusion (CTP) allows the assessment of the functional relevance of coronary artery stenosis. This study investigates to what extent the contour sharpness of sequences acquired by dynamic myocardial CTP is influenced by the following noise reduction methods: temporal averaging and adaptive iterative dose reduction 3D (AIDR 3D).

Materials And Methods: Dynamic myocardial CT perfusion was conducted in 29 patients at a dose level of 9.5±2.0 mSv and was reconstructed with both filtered back projection (FBP) and strong levels of AIDR 3D. Temporal averaging to reduce noise was performed as a post-processing step by combining two, three, four, six and eight original consecutive 3D datasets. We evaluated the contour sharpness at four distinct edges of the left-ventricular myocardium based on two different approaches: the distance between 25% and 75% of the maximal grey value (d) and the slope in the contour (m).

Results: Iterative reconstruction reduced contour sharpness: both measures of contour sharpness performed better for FBP than for AIDR 3D (d = 1.7±0.4 mm versus 2.0±0.5 mm, p>0.059 at all edges; m = 255.9±123.9 HU/mm versus 160.6±123.5 HU/mm; p<0.023 for all edges). Increasing levels of temporal averaging degraded contour sharpness. When FBP reconstruction was applied, contour sharpness was best without temporal averaging (d = 1.7±0.4 mm, m = 255.9±123.9 HU/mm) and poorest for the strongest levels of temporal averaging (d = 2.1±0.3 mm, m = 142.2±104.9 HU/mm; comparison between lowest and highest temporal averaging level: for d p>0.052 at all edges and for m p<0.001 at all edges).

Conclusion: The use of both temporal averaging and iterative reconstruction degrades objective contour sharpness parameters of dynamic myocardial CTP. Thus, further advances in image processing are needed to optimise contour sharpness of 4D myocardial CTP.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0205922PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6191149PMC
April 2019

Ectoparasite communities of small-bodied Malagasy primates: seasonal and socioecological influences on tick, mite and lice infestation of Microcebus murinus and M. ravelobensis in northwestern Madagascar.

Parasit Vectors 2018 Aug 8;11(1):459. Epub 2018 Aug 8.

Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany.

Background: Ectoparasitic infections are of particular interest for endangered wildlife, as ectoparasites are potential vectors for inter- and intraspecific pathogen transmission and may be indicators to assess the health status of endangered populations. Here, ectoparasite dynamics in sympatric populations of two Malagasy mouse lemur species, Microcebus murinus and M. ravelobensis, were investigated over an 11-month period. Furthermore, the animals' body mass was determined as an indicator of body condition, reflecting seasonal and environmental challenges. Living in sympatry, the two study species experience the same environmental conditions, but show distinct differences in socioecology: Microcebus murinus sleeps in tree holes, either solitarily (males) or sometimes in groups (females only), whereas M. ravelobensis sleeps in mixed-sex groups in more open vegetation.

Results: Both mouse lemur species hosted ticks (Haemaphysalis sp.), lice (Lemurpediculus sp.) and mites (Trombiculidae gen. sp. and Laelaptidae gen. sp.). Host species, as well as temporal variations (month and year), were identified as the main factors influencing infestation. Tick infestation peaked in the late dry season and was significantly more often observed in M. murinus (P = 0.011), while lice infestation was more likely in M. ravelobensis (P < 0.001) and showed a continuous increase over the course of the dry season. Genetic analyses identified Lemurpediculus sp. infesting both mouse lemur species. Ticks morphologically conform to H. lemuris, but genetic analysis showed a clear differentiation of the specimens collected in this study, suggesting a potentially new tick species. Host body mass decreased from the early to the late dry season, indicating nutritional stress during this period, which may render individuals more susceptible to parasitic infections.

Conclusions: Seasonal differences and species-specific variations in sleeping site ecology in terms of sleeping site type and sociality were determined as key factors influencing ectoparasitism in M. murinus and M. ravelobensis. This needs to be taken into account when evaluating ectoparasite infestations at a given time point. The detection of the same parasite species on two closely related and sympatric host species furthermore indicates a potential pathway for disease transmission, not only within but also between lemur species.
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http://dx.doi.org/10.1186/s13071-018-3034-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6083607PMC
August 2018

Are sleeping site ecology and season linked to intestinal helminth prevalence and diversity in two sympatric, nocturnal and arboreal primate hosts (Lepilemur edwardsi and Avahi occidentalis)?

BMC Ecol 2018 07 13;18(1):22. Epub 2018 Jul 13.

Institute for Parasitology, University of Veterinary Medicine Hannover, Buenteweg 17, 30559, Hannover, Germany.

Background: Various factors, such as climate, body size and sociality are often linked to parasitism. This constrains the identification of other determinants driving parasite infections. Here, we investigate for the first time intestinal parasites in two sympatric arboreal primate species, which share similar activity patterns, feeding ecology, body size and sociality, and cope with the same climate conditions, but differ in sleeping site ecology: the Milne-Edward's sportive lemur (Lepilemur edwardsi) and the Western woolly lemur (Avahi occidentalis). Comparison of these two species aimed to test whether differences in sleeping sites are related to differences in parasite infection patterns. Additionally, gender and seasonal factors were taken into account. Animals were radio-collared to record their sleeping site dynamics and to collect fecal samples to assess intestinal parasitism during both the dry and the rainy season.

Results: Only low parasite diversity was detected, which is attributable to the strict arboreal lifestyle of these lemurs, limiting their contact with infective parasite stages. L. edwardsi, which sleeps in tree holes and repeatedly uses the same sleeping site, excreted eggs of strongyle and oxyurid nematodes, whereby strongyles always occurred in coinfection with oxyurids. In contrast, A. occidentalis, which sleeps on open branches and frequently changes sleeping sites, only excreted eggs of strongyle nematodes. This difference can be attributed to a potential favorable environment presented by tree holes for infective stages, facilitating parasitic transmission. Additionally, Strongylida in A. occidentalis were only observed in the rainy season, suggesting an arrested development during the dry season in the nematodes' life cycle. Males and females of both lemur species showed the same frequency of parasitism. No differences in body mass of infected and non-infected individuals were observed, indicating that the animals' body condition remains unaffected by the detected gastrointestinal parasites.

Conclusions: The comparison of two primate hosts with a very similar lifestyle suggests an influence of the sleeping site ecology on intestinal parasites. In A. occidentalis there was a clear seasonal difference in strongyle egg excretion. These results improve our understanding of the parasite ecology in these endangered primate species, which may be critical in the light of species conservation.
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http://dx.doi.org/10.1186/s12898-018-0178-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6043982PMC
July 2018

Co-infection patterns of intestinal parasites in arboreal primates (proboscis monkeys, ) in Borneo.

Int J Parasitol Parasites Wildl 2017 Dec 20;6(3):320-329. Epub 2017 Sep 20.

Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Buenteweg 17, 30559 Hannover, Germany.

Non-human primates of South-East Asia remain under-studied concerning parasite epidemiology and co-infection patterns. Simultaneously, efforts in conservation demand knowledge of parasite abundance and biodiversity in threatened species. The Endangered proboscis monkey, , a primate flagship species for conservation in Borneo, was investigated in the present study. Habitat loss and fragmentation are among the greatest threats to bachelor and harem groups of this folivorous colobine. Designed as a follow-up study, prevalence and co-infection status of intestinal parasites from in a protected area in Malaysian Borneo were analyzed from fecal samples using a flotation method. For the first time, the intestinal parasite co-infection patterns were examined using quantitative analyses. Overall, 92.3% of fecal samples (N = 652) were positive for helminth eggs. Five helminth groups were detected: (1) trichurids (82.7% prevalence) including spp. (82.1%) and spp. (1.4%), (2) strongyles (58.9%) including spp. (48.5%) and spp. (22.8%), (3) (32.7%), (4) (8.6%), and (5) spp. (5.5%). On average, an individual was co-infected with two different groups. Significant positive associations were found for co-infections of trichurids with strongyles and as well as with and strongyles. This study shows a high prevalence of various gastrointestinal helminths with potential transmission pathways primarily related to soil and with zoonotic relevance in wild proboscis monkeys in their remaining natural habitats. Observed positive associations of trichurids with strongyles and spp. may result from the high prevalence of trichurids. Similarly, positive associations between and were found, both of which typically occur predominantly in juvenile hosts. These findings should be considered when proposing conservation actions in altered habitats nearby human settlements and when managing captive populations.
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http://dx.doi.org/10.1016/j.ijppaw.2017.09.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6031963PMC
December 2017

Correction to: Applicability and accuracy of pretest probability calculations implemented in the NICE clinical guideline for decision making about imaging in patients with chest pain of recent onset.

Eur Radiol 2018 11;28(11):4919-4921

Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.

The original version of this article, published on 19 March 2018, unfortunately contained a mistake. The following correction has therefore been made in the original: The names of the authors Philipp A. Kaufmann, Ronny Ralf Buechel and Bernhard A. Herzog were presented incorrectly.
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http://dx.doi.org/10.1007/s00330-018-5521-0DOI Listing
November 2018

Variation in reproduction of the smallest-bodied primate radiation, the mouse lemurs (Microcebus spp.): A synopsis.

Am J Primatol 2018 07 16;80(7):e22874. Epub 2018 May 16.

Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.

Reproduction is a fundamental trait in the life history of any species and contributes to species diversity and evolution. Here, we aim to review the barely known variation in reproductive patterns of the smallest-bodied primate radiation, the Malagasy mouse lemurs, focusing on twelve species of four phylogenetic clades. We present a new reproductive field dataset collected between May and November 1996-2016 for nine species (Microcebus murinus, M. myoxinus, M. ravelobensis, M. bongolavensis, M. danfossi, M. sambiranensis, M. margothmarshae, M. mamiratra, and M. lehilahytsara) and add published field information on three additional species. In the majority of species, the estrus of females was recorded in the period of long days (day length longer than 12 hr), whereas male testes size increased about one to three months prior to this. Reproductive schedules varied considerably between the four clades. Sympatric species-pairs of different clades differed in the timing of female and male reproduction, suggesting strong phylogenetic constraints. Populations of the same species in a different ecological setting varied in the onset of reproduction, suggesting substantial environmental plasticity. Warm temperatures and rainfall throughout the year may allow for less expressed reproductive seasonality. Our results suggest that an interplay between phylogenetic relatedness, ambient temperature (as a proxy for thermo regulatory constraints), and rainfall (as a proxy for food availability), may best explain this variation. Findings further point to a more complex control of mouse lemur reproduction than previously described and illuminate phylogenetic constraints and adaptive potentials in behavioral reaction norms of a species-rich primate radiation.
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http://dx.doi.org/10.1002/ajp.22874DOI Listing
July 2018

First comparative approach to touchscreen-based visual object-location paired-associates learning in humans (Homo sapiens) and a nonhuman primate (Microcebus murinus).

J Comp Psychol 2018 08 10;132(3):315-325. Epub 2018 May 10.

Institute of Zoology, University of Veterinary Medicine Hannover.

A recent study suggests that a specific, touchscreen-based task on visual object-location paired-associates learning (PAL), the so-called Different PAL (dPAL) task, allows effective translation from animal models to humans. Here, we adapted the task to a nonhuman primate (NHP), the gray mouse lemur, and provide first evidence for the successful comparative application of the task to humans and NHPs. Young human adults reach the learning criterion after considerably less sessions (one order of magnitude) than young, adult NHPs, which is likely due to faster and voluntary rejection of ineffective learning strategies in humans and almost immediate rule generalization. At criterion, however, all human subjects solved the task by either applying a visuospatial rule or, more rarely, by memorizing all possible stimulus combinations and responding correctly based on global visual information. An error-profile analysis in humans and NHPs suggests that successful learning in NHPs is comparably based either on the formation of visuospatial associative links or on more reflexive, visually guided stimulus-response learning. The classification in the NHPs is further supported by an analysis of the individual response latencies, which are considerably higher in NHPs classified as spatial learners. Our results, therefore, support the high translational potential of the standardized, touchscreen-based dPAL task by providing first empirical and comparable evidence for two different cognitive processes underlying dPAL performance in primates. (PsycINFO Database Record
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http://dx.doi.org/10.1037/com0000116DOI Listing
August 2018

Neural Progenitors in the Developing Neocortex of the Northern Tree Shrew () Show a Closer Relationship to Gyrencephalic Primates Than to Lissencephalic Rodents.

Front Neuroanat 2018 19;12:29. Epub 2018 Apr 19.

Institute of Veterinary Anatomy, Histology and Embryology, University of Leipzig, Leipzig, Germany.

The neocortex is the most complex part of the mammalian brain and as such it has undergone tremendous expansion during evolution, especially in primates. The majority of neocortical neurons originate from distinct neural stem and progenitor cells (NPCs) located in the ventricular and subventricular zone (SVZ). Previous studies revealed that the SVZ thickness as well as the abundance and distribution of NPCs, especially that of basal radial glia (bRG), differ markedly between the lissencephalic rodent and gyrencephalic primate neocortex. The northern tree shrew () is a rat-sized mammal with a high brain to body mass ratio, which stands phylogenetically mid-way between rodents and primates. Our study provides - for the first time - detailed data on the presence, abundance and distribution of bRG and other distinct NPCs in the developing neocortex of the northern tree shrew (). We show that the developing tree shrew neocortex is characterized by an expanded SVZ, a high abundance of Pax6+ NPCs in the SVZ, and a relatively high percentage of bRG at peak of upper-layer neurogenesis. We further demonstrate that key features of tree shrew neocortex development, e.g., the presence, abundance and distribution of distinct NPCs, are closer related to those of gyrencephalic primates than to those of ferret and lissencephalic rodents. Together, our study provides novel insight into the evolution of bRG and other distinct NPCs in the neocortex development of Euarchontoglires and introduces the tree shrew as a potential novel model organism in the area of human brain development and developmental disorders.
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http://dx.doi.org/10.3389/fnana.2018.00029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5917011PMC
April 2018

High frequency/ultrasonic communication in a critically endangered nocturnal primate, Claire's mouse lemur (Microcebus mamiratra).

Am J Primatol 2018 06 2;80(6):e22866. Epub 2018 May 2.

Institute of Zoology, University of Veterinary Medicine, Hannover, Germany.

The critically endangered Claire's mouse lemur, only found in the evergreen rain forest of the National Park Lokobe (LNP) and a few lowland evergreen rain forest fragments of northern Madagascar, was described recently. The present study provides the first quantified information on vocal acoustics of calls, sound associated behavioral context, acoustic niche, and vocal activity of this species. We recorded vocal and social behavior of six male-female and six male-male dyads in a standardized social-encounter paradigm in June and July 2016 at the LNP, Nosy Bé island. Over six successive nights per dyad, we audio recorded and observed behaviors for 3 hr at the beginning of the activity period. Based on the visual inspection of spectrograms and standardized multiparametric sound analysis, we identified seven different call types. Call types can be discriminated based on a combination of harmonicity, fundamental frequency variation, call duration, and degree of tonality. Acoustic features of tonal call types showed that for communication, mouse lemurs use the cryptic, high frequency/ultrasonic frequency niche. Two call types, the Tsak and the Grunt call, were emitted most frequently. Significant differences in vocal activity of the Tsak call were found between male-female and male-male dyads, linked primarily to agonistic conflicts. Dominant mouse lemurs vocalized more than subdominant ones, suggesting that signaling may present an honest indicator of fitness. A comparison of our findings of the Claire's mouse lemur with published findings of five bioacoustically studied mouse lemur species points to the notion that a complex interplay between ecology, predation pressure, and phylogenetic relatedness may shape the evolution of acoustic divergence between species in this smallest-bodied primate radiation. Thus, comparative bioacoustic studies, using standardized procedures, are promising to unravel the role of vocalization for primate species diversity and evolution and for identifying candidates for vocalization-based non-invasive monitoring for conservation purposes.
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http://dx.doi.org/10.1002/ajp.22866DOI Listing
June 2018

A New Species of Sucking Louse (Phthiraptera: Anoplura: Polyplacidae) From the Gray Mouse Lemur, Microcebus murinus (Primates: Cheirogaleidae), in Madagascar.

J Med Entomol 2018 06;55(4):910-914

School of Forestry and Wildlife Sciences, College of Veterinary Sciences, Auburn University, AL.

Lemurpediculus madagascariensis sp. nov. (Phthiraptera: Anoplura: Polyplacidae) is described from the Gray Mouse lemur, Microcebus murinus (J. F. Miller) (Primates: Cheirogaleidae), from Ankarafantsika National Park, Madagascar. Lemurs were trapped using Sherman Live Traps and visually inspected for lice, which were preserved in 90% ethanol. Adults of both sexes and the third-instar nymph of the new species are illustrated and distinguished from the four previously known species of Lemurpediculus: L. verruculosus (Ward); L. petterorum Paulian; L. claytoni Durden, Blanco, and Seabolt; and L. robbinsi Durden, Blanco, and Seabolt. It is not known if the new species of louse is a vector of any pathogens or parasites.
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http://dx.doi.org/10.1093/jme/tjy046DOI Listing
June 2018
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