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Tenofovir-emtricitabine (TDF-FTC) pre-exposure prophylaxis (PrEP) has been found to be effective for prevention of HIV infection in several clinical trials. Two studies of TDF PrEP among men who have sex with men showed slight bone mineral density (BMD) loss. We investigated the effect of TDF and the interaction of TDF and hormonal contraception on BMD among HIV-uninfected African men and women.We evaluated the effects on BMD of using daily oral TDF-FTC compared to placebo among heterosexual men and women aged 18-29 years enrolled in the Botswana TDF2 PrEP study. Participants had BMD measurements at baseline and thereafter at 6-month intervals with dual-energy X-ray absorptiometry (DXA) scans at the hip, spine, and forearm.A total of 220 participants (108 TDF-FTC, 112 placebo) had baseline DXA BMD measurements at three anatomic sites. Fifteen (6.8%) participants had low baseline BMD (z-score of 3.0% at any anatomic site at any time after baseline were significantly greater for the TDF-FTC treatment group [34/68 (50.0%) TDF-FTC vs. 26/79 (32.9%) placebo; p = 0.04]. There was a small but significant difference in the mean percent change in BMD from baseline for TDF-FTC versus placebo at all three sites at month 30 [forearm -0.84% (p = 0.01), spine -1.62% (p = 0.0002), hip -1.51% (p = 0.003)].Use of TDF-FTC was associated with a small but statistically significant decrease in BMD at the forearm, hip and lumbar spine. A high percentage (6.8%) of healthy Batswana young adults had abnormal baseline BMD Further evaluation is needed of the longer-term use of TDF in HIV-uninfected persons.ClinicalTrials.gov NCT00448669.

Abstract Background This study evaluates the association of diuresis and hydration through a new monitoring indicator called $${U}_{sen}$$ U sen and the risk of acute kidney injury in patients treated with cisplatin based-EXTREME regimen. Methods We retrospectively reviewed all the cycles of patients with recurrent and/or metastatic head and neck cancer who received cisplatin based-EXTREME regimen from June 2008 to July 2022. Hydration regimen, urine output and concomitant treatments data were collected on the day of cisplatin infusion and the following day of each course received. Results Of the 110 courses received by 46 patients, 38 (34.5%) results in AKI. No patient characteristics showed a significant difference between AKI (70%) and non-AKI (30%) group. In univariate analysis, dose reduction of cisplatin (odds ratio = 0.166 [0.04; 0.75], p = 0.01)) and $${U}_{sen}$$ U sen >8 (odds ratio = 0.316 [0.133; 0.755], p = 0.015) and cardiac treatments (odds ratio = 3.24 [1.26; 8.52], p = 0.02) were significantly associated with AKI risk. In multivariate analysis, cisplatin dose reduction (odds ratio = 0.129 [0.0241; 0.687], p = 0.016) and $${U}_{sen}$$ U sen >8 (odds ratio = 0.184 [0.0648; 0.523], p = 0.0015) were associated with a risk reduction of cisplatin-related AKI. Concomitant administration of cardiac treatments (odds ratio = 3.18 [1.1; 9.22], p = 0.033) showed an increased risk of cisplatin-related AKI. Conclusion The combination of diuresis and i.v. hydration through the $${U}_{sen}$$ U sen composite score was shown to be associated with cisplatin-induced AKI risk in patients treated with cisplatin based EXTREME regimen. It could be used as a practical indicator to trigger specific clinical management to limit the risk of cisplatin induced AKI.

Abstract Millions of traumatic brain injuries (TBIs) occur annually. TBIs commonly result from falls, traffic accidents, and sports-related injuries, all of which involve rotational acceleration/deceleration of the brain. During these injuries, the brain endures a multitude of primary insults including compression of brain tissue, damaged vasculature, and diffuse axonal injury. All of these deleterious effects can contribute to secondary brain ischemia, cellular death, and neuroinflammation that progress for weeks, months, and lifetime after injury. While the linear effects of head trauma have been extensively modeled, less is known about how rotational injuries mediate neuronal damage following injury. Here, we developed a new model of repetitive rotational head trauma in rodents and demonstrated acute and prolonged pathological, behavioral, and electrophysiological effects of rotational TBI (rTBI). We identify aberrant Cyclin-dependent kinase 5 (Cdk5) activity as a principal mediator of rTBI. We utilized Cdk5-enriched phosphoproteomics to uncover potential downstream mediators of rTBI and show pharmacological inhibition of Cdk5 reduces the cognitive and pathological consequences of injury. These studies contribute meaningfully to our understanding of the mechanisms of rTBI and how they may be effectively treated.

Football exposes its players to traumatic brain, neck, and spinal injury. It is unknown whether the adolescent football player develops imaging abnormalities of the brain and spine that are detectable on magnetic resonance imaging (MRI). The objective of this observational study was to identify potential MRI signatures of early brain and cervical spine (c-spine) injury in high school football players. Eighteen football players (mean age, 17.0???1.5 years; mean career length, 6.3???4.0 years) had a baseline brain MRI, and 7 had a follow-up scan 9?42 months later. C-spine MRIs were performed on 11 of the 18 subjects, and 5 had a follow-up scan. C-spine MRIs from 12 age-matched hospital controls were also retrospectively retrieved. Brain MRIs were reviewed by a neuroradiologist, and no cerebral microbleeds were detected. Three readers (a neuroradiologist, a neurosurgeon, and an orthopedic spine surgeon) studied the cervical intervertebral discs at six different cervical levels and graded degeneration using an established five-grade scoring system. We observed no statistically significant difference in disc degeneration or any trend toward increased disc degeneration in the c-spine of football players as compared with age-matched controls. Further research is needed to validate our findings and better understand the true impact of contact sports on young athletes.

ABSTRACT Although parasite entry through breaks in the skin or mucosa is one of the main routes of natural transmission of Trypanosoma cruzi, little is known about the host cell types initially invaded nor the ability of those host cells to initiate immune responses at the site of infection. To gain insights into these early events, we studied the fate of fluorescently tagged T. cruzi delivered subcutaneously in mouse footpads or ears. We demonstrate that the majority of parasites introduced into the skin initially proliferate there until 8 to 10 days postinfection, when the parasite load decreases. This decline in parasite numbers is dependent on the presence of an intact T cell compartment and on the ability of hosts to produce gamma interferon (IFN-γ). Many of the parasite-containing cells at the initial infection site display a macrophage/monocyte phenotype but with low expression of activation markers, suggesting that these cells provide an early niche for T. cruzi proliferation, rather than being active in parasite control. It is only after the first round of T. cruzi replication and release from host cells that signs of immune activation and control of parasites become apparent. The delay in the activation and failure to rapidly control parasite replication are observed even when T. cruzi-primed T cells are present, such as in chronically infected mice. This failure of a primed immune system to recognize and react prior to extensive parasite expansion at the infection site likely poses a significant challenge for the development of vaccines aiming to prevent T. cruzi infection. IMPORTANCE Trypanosoma cruzi, the parasite causing Chagas disease, usually infects through the mucosa or breaks in the skin, but little is known about the parasite's fate at the site of entry or the early events involving immune control there. Here, we track the local proliferation and subsequent dissemination of fluorescently tagged T. cruzi and the initial immune response at the point of entry. We show that T. cruzi preferentially infects innate immune cells in the skin and that the stimulation of an adaptive T cell response does not occur until after the release of parasites from this first round of infected host cells. This first immunologically “silent” proliferation occurs even in the presence of a strong immune T cell memory generated by previous infection. This capacity of T. cruzi to establish infections while avoiding initial immune recognition has important implications for the potential to develop vaccines to prevent T. cruzi infection.

We study numerically the reconfiguration process of colliding m=1/2 strength disclinations in an achiral nematic liquid crystal (NLC). A Landau–de Gennes approach in terms of tensor nematic-order parameters is used. Initially, different pairs m1,m2 of parallel wedge disclination lines connecting opposite substrates confining the NLC in a plane-parallel cell of a thickness h are imposed: {1/2,1/2}, {−1/2,−1/2} and {−1/2,1/2}. The collisions are imposed by the relative rotation of the azimuthal angle θ of the substrates that strongly pin the defect end points. Pairs {1/2,1/2} and {−1/2,−1/2} “rewire” at the critical angle θc1=3π4 in all cases studied. On the other hand, two qualitatively different scenarios are observed for {−1/2,1/2}. In the thinner film regime hhc, the colliding disclinations at θc2 reconfigure into boojum-like twist disclinations.

Background: Bone graft extenders are being used more in spine surgery as a substitute for iliac crest bone graft. However, potential conflict of interest could impact average fusion rates. The purpose of this study was to evaluate whether fusion rates reported in the literature were different in papers evaluating bone graft substitutes and extenders when there was potential conflict of interest versus no potential conflict of interest. Methods: Pubmed was searched for studies evaluating fusion rates when bone graft extenders including demineralized bone matrix, hydroxyapatite, and tricalcium sulfate were used. Studies were screened for one or two level fusions and for degenerative spinal conditions. The average fusion rates of subgroups were compared using unpaired Student's t-tests. Results: 1928 studies were evaluated. 86 studies were included in the study. The fusion rates varied from 4 to 100%. There were 24 studies with a potential conflict of interest and 62 studies with no conflict of interest. The average fusion rate of all the studies was 84.63% with standard deviation of 18.33%. The average fusion rates of those studies with conflict of interest was 80.93% versus 86.06% without conflict of interest. This was not statistically significant (p>0.07). The average fusion rate of studies evaluated by CT scan was 79.8% versus 87.9% without CT. The average fusion rate of studies that employed an independent reviewer to evaluate the fusion was 82.61% versus 85.63% for studies with no independent reviewer. Conclusion: There is a great variability in the reported fusion rates of bone graft extenders. Counter to expectations, average fusion rates were lower in the studies where there was a potential conflict of interest. The use of CT scans and an independent reviewer seem to account for the lower reported fusion rates, and may be a means of negating the potential conflicts of interest in fusion studies. Level of Evidence: 2

Background: Previous studies show an increasing incidence of gram-negative organisms in surgical site infections after spine surgery. This study is looking for the association of the post-operative prophylactic use of Bactrim and the gram-negative surgical site infection after lumbar spine surgery Methods: Patients who underwent lumbar spine surgery between August 2010 and December 2019 at the institution were retrospectively reviewed. Results: There were 11 infections out of 511 cases where no oral antibiotics were given (2.2%). There were 2 infections out of 84 cases where Bactrim was given (2.4%). This was not statistically significant (P=0.89). The organisms cultured from the no oral antibiotic group were 8 cases of methicillin sensitive Staphylococcus aureus (MSSA), 1 case of E. coli, 1 case of Pseudomonas aeruginosa, 1 case of MRSA. The organisms cultured from the Bactrim group were 1 case of MRSA, and 1 case of combined Citrobacter freundii and methicillin sensitive Staphylococcus aureus (MSSA). Conclusion: There was no statistically significant difference in SSIs when Bactrim was given for two weeks after surgery. However, two subjects who developed infection from the Bactrim group were paradoxically affected by gram-negative and antibiotic resistant organisms. So, clinicians should be judicious in their use of oral antibiotics after spine surgery. Level of Evidence: III

Burning velocities of binary and ternary pyrotechnic compositions are measured in gutter. The study focuses on the determination of the joint influence of several parameters: oxidant/reducer ratio, reducer granulometry, and binder content. Measurements are performed following the standard NF T70-541 for burning velocity estimation using an optical acquisition method. Binder content has a linear influence on the burning velocity with a pivot point in slope at supposed stoichiometry. Changing the granulometric class of metallic reducer shows to have different influences before and beyond a 20% diameter reduction.

Using a Landau–de Gennes approach, we study the impact of confinement topology, geometry and external fields on the spatial positioning of nematic topological defects (TDs). In quasi two-dimensional systems we demonstrate that a confinement-enforced total topological charge of m > 1/2 decays into elementary TDs bearing a charge of m = 1/2. These assemble close to the bounding substrate to enable essentially bulk-like uniform nematic ordering in the central part of a system. This effect is reminiscent of the Faraday cavity phenomenon in electrostatics. We observe that in certain confinement geometries, varying the correlation length size of the order parameter could trigger a global rotation of an assembly of TDs. Finally, we show that an external electric field could be used to drag the boojum fingertip towards the interior of the confinement cell. Assemblies of TDs could be exploited as traps for appropriate nanoparticles, opening several opportunities for the development of functional nanodevices.

The field of liquid crystals is constantly reinventing itself, evolving from measurements of elastic constants and devices such as the simple nematic twist cell in the 1970s to topological defects, nanoparticle inclusions, and smart sensors today [...]

We studied numerically external stimuli enforced annihilation of a pair of daughter nematic topological defect (TD) assemblies bearing a relatively strong topological charge |m|=3/2. A Landau- de Gennes phenomenological approach in terms of tensor nematic order parameter was used in an effectively two-dimensional Cartesian coordinate system, where spatial variations along the z-axis were neglected. A pair of {m=3/2,m=−3/2} was enforced by an appropriate surface anchoring field, mimicking an experimental sample realization using the atomic force microscope (AFM) scribing method. Furthermore, defects were confined within a rectangular boundary that imposes strong tangential anchoring. This setup enabled complex and counter-intuitive annihilation processes on varying relevant parameters. We present two qualitatively different annihilation paths, where we either gradually reduced the relative surface anchoring field importance or increased an external in-plane spatially homogeneous electric field E. The creation and depinning of additional defect pairs {12,−12} mediated the annihilation in such a geometry. Furthermore, we illustrate the absorption of TDs by sharp edges of the confining boundary, accompanied by m=±1/4↔∓1/4 winding reversal of edge singularities, and also E-driven zero-dimensional to one-dimensional defect core transformation.

In this article, we theoretically and numerically study the chirality and saddle-splay elastic constant ( K 24 ) -enabled stability of multiple twist-like nematic liquid crystal (LC) structures in cylindrical confinement. We focus on the so-called radially z-twisted (RZT) and radially twisted (RT) configurations, which simultaneously exhibit twists in different spatial directions. We express the free energies of the structures in terms of dimensionless wave vectors, which characterise the structures and play the roles of order parameters. The impact of different confinement anchoring conditions is explored. A simple Landau-type analysis provides an insight into how different model parameters influence the stability of structures. We determine conditions for which the structures are stable in chiral and also nonchiral LCs. In particular, we find that the RZT structure could exhibit macroscopic chirality inversion upon varying the relevant parameters. This phenomenon could be exploited for the measurement of K 24 .

Topological defects appear in symmetry breaking phase transitions and are ubiquitous throughout Nature. As an ideal testbed for their study, defect configurations in nematic liquid crystals (NLCs) could be exploited in a rich variety of technological applications. Here we report on robust theoretical and experimental investigations in which an external electric field is used to switch between predetermined stable chargeless disclination patterns in a nematic cell, where the cell is sufficiently thick that the disclinations start and terminate at the same surface. The different defect configurations are stabilized by a master substrate that enforces a lattice of surface defects exhibiting zero total topological charge value. Theoretically, we model disclination configurations using a Landau-de Gennes phenomenological model. Experimentally, we enable diverse defect patterns by implementing an in-house-developed atomic force measurement scribing method, where NLC configurations are monitored via polarized optical microscopy. We show numerically and experimentally that an “alphabet” of up to 18 unique line defect configurations can be stabilized in a 4 × 4 lattice of alternating s=±1 surface defects, which can be “rewired” multistably using appropriate field manipulation. Our proof-of-concept mechanism may lead to a variety of applications, such as multistable optical displays and rewirable nanowires. Our studies also are of interest from a fundamental perspective. We demonstrate that a chargeless line could simultaneously exhibit defect-antidefect properties. Consequently, a pair of such antiparallel disclinations exhibits an attractive interaction. For a sufficiently closely spaced pair of substrate-pinned defects, this interaction could trigger rewiring, or annihilation if defects are depinned.

Liquid crystals were discovered by Friedrich Reinitzer in 1888 when he observed colors in cholesterol derivatives that are characteristic of highly birefringent materials [...]

Promoters with tissue-specific activity are very useful to address cell-autonomous and non cell autonomous functions of candidate genes. Although this strategy is widely used in Arabidopsis thaliana, its use to study tissue-specific regulation of root symbiotic interactions in legumes has only started recently. Moreover, using tissue specific promoter activity to drive a GAL4-VP16 chimeric transcription factor that can bind short upstream activation sequences (UAS) is an efficient way to target and enhance the expression of any gene of interest. Here, we developed a collection of promoters with different root cell layers specific activities in Medicago truncatula and tested their abilities to drive the expression of a chimeric GAL4-VP16 transcription factor in a trans-activation UAS: β-Glucuronidase (GUS) reporter gene system. By developing a binary vector devoted to modular Golden Gate cloning together with a collection of adapted tissue specific promoters and coding sequences we could test the activity of four of these promoters in trans-activation GAL4/UAS systems and compare them to "classical" promoter GUS fusions. Roots showing high levels of tissue specific expression of the GUS activity could be obtained with this trans-activation system. We therefore provide the legume community with new tools for efficient modular Golden Gate cloning, tissue specific expression and a trans-activation system. This study provides the ground work for future development of stable transgenic lines in Medicago truncatula.

The Medicago truncatula DMI3 gene encodes a calcium- and calmodulin-dependent protein kinase (CCaMK) that is necessary for the establishment of both rhizobial and mycorrhizal symbioses. The two symbiotic signaling pathways diverge downstream of DMI3; therefore, it has been proposed that legumes have evolved a particular form of CCaMK, acting like a switch able both to discriminate between rhizobial and mycorrhizal calcium signatures and to trigger the appropriate downstream signaling pathway. To test this hypothesis, we examined whether a CCaMK gene from a nonlegume species was able to restore the rhizobial symbiotic properties of a M. truncatula dmi3 mutant. Our results show that a CCaMK gene from rice can restore nodule formation, indicating that CCaMKs from nonlegumes can interpret the calcium signature elicited by rhizobial Nod factors and activate the appropriate downstream target. The nodules did not contain bacteria, which suggests that DMI3 is also involved in the control of the infection process.

The objective of this review was to discuss viral infection byHuman papillomavirus because of its elevated incidence amongwomen and their respective partners, as well as the relationbetween the virus groups found in women with cervicalintraepithelial neoplasia or normal women and their respectivepartners. The presence of human papillomavirus in male partnersdoes not necessarily implicate the presence of humanpapillomavirus or even cervical epithelial neoplasia in their femalepartners. Peniscopy, penile biopsy, and Human papillomavirusmolecular biology tests are discussed in the review. The medicalevaluation of male partners is essential to treat clinical lesionsand to make them aware of the sexually transmitted character ofthis infection and the need for peniscopy.

The DMI1, DMI2, and DMI3 genes of Medicago truncatula, which are required for both nodulation and mycorrhization, control early steps of Nod factor signal transduction. Here, we have used diverse approaches to pave the way for the map-based cloning of these genes. Molecular amplification fragment length polymorphism markers linked to the three genes were identified by bulked segregant analysis. Integration of these markers into the general genetic map of M. truncatula revealed that DMI1, DMI2, and DMI3 are located on linkage groups 2, 5, and 8, respectively. Cytogenetic studies using fluorescent in situ hybridization (FISH) on mitotic and pachytene chromosomes confirmed the location of DMI1, DMI2, and DMI3 on chromosomes 2, 5, and 8. FISH-pachytene studies revealed that the three genes are in euchromatic regions of the genome, with a ratio of genetic to cytogenetic distances between 0.8 and 1.6 cM per μm in the DMI1, DMI2, and DMI3 regions. Through grafting experiments, we showed that the genetic control of the dmi1, dmi2, and dmi3 nodulation phenotypes is determined at the root level. This means that mutants can be transformed by Agrobacterium rhizogenes to accelerate the complementation step of map-based cloning projects for DMI1, DMI2, and DMI3.

Thin smectic liquid crystal films with competing boundary conditions (planar and homeotropic at opposing surfaces) form well-known striated structures known as “oily streaks”, which are a series of hemicylindrical caps that run perpendicular to the easy axis of the planar substrate. The streaks vanish on heating into the nematic phase, where the film becomes uniform and exhibits hybrid alignment. On adding sufficient reactive mesogen and polymerizing, the oily streak texture is maintained on heating through the entire nematic phase until reaching the bulk isotropic phase, above which the texture vanishes. Depending on the liquid crystal thickness, the oily streak structure may be retrieved after cooling, which demonstrates the strong impact of the polymer backbone on the liquid crystal texture. Polarizing optical, atomic force, and scanning electron microscopy data are presented.

Medicago truncatula, a diploid autogamous legume, is currently being developed as a model plant for the study of root endosymbiotic associations, including nodulation and mycorrhizal colonization. An important requirement for such a plant is the possibility of rapidly introducing and analyzing chimeric gene constructs in root tissues. For this reason, we developed and optimized a convenient protocol for Agrobacterium rhizogenes-mediated transformation of M. truncatula. This unusual protocol, which involves the inoculation of sectioned seedling radicles, results in rapid and efficient hairy root organogenesis and the subsequent development of vigorous “composite plants.” In addition, we found that kanamycin can be used to select for the co-transformation of hairy roots directly with gene constructs of interest. M. truncatula composite plant hairy roots have a similar morphology to normal roots and can be nodulated successfully by their nitrogen-fixing symbiotic partner, Sinorhizobium meliloti. Furthermore, spatiotemporal expression of the Nod factor-responsive reporter p MtENOD11-gusA in hairy root epidermal tissues is indistinguishable from that observed in Agrobacterium tumefaciens-transformed lines. M. truncatula hairy root explants can be propagated in vitro, and we demonstrate that these clonal lines can be colonized by endomycorrhizal fungi such as Glomus intraradices with the formation of arbus-cules within cortical cells. Our results suggest that M. truncatula hairy roots represent a particularly attractive system with which to study endosymbiotic associations in transgenically modified roots.

We present a case of leiomyoma of the bladder consideringdiagnosis, treatment and literature review. A leiomyoma of thebladder was diagnosed in a 60-year-old woman based on physicalexamination, urinary tract imaging (ultrasonography, computedtomography and magnetic resonance imaging) andcystourethroscopy with biopsy of the lesion. Cystourethroscopyshowed a bladder tumor covered by normal epithelium.Management included complete transurethral resection with norelapse after a seven-month follow-up.

Only species belonging to the Fabid clade, limited to four classes and ten families of Angiosperms, are able to form nitrogen-fixing root nodule symbioses (RNS) with soil bacteria. This concerns plants of the legume family (Fabaceae) and Parasponia (Cannabaceae) associated with the Gram-negative proteobacteria collectively called rhizobia and actinorhizal plants associated with the Gram-positive actinomycetes of the genus Frankia. Calcium and calmodulin-dependent protein kinase (CCaMK) is a key component of the common signaling pathway leading to both rhizobial and arbuscular mycorrhizal symbioses (AM) and plays a central role in cross-signaling between root nodule organogenesis and infection processes. Here, we show that CCaMK is also needed for successful actinorhiza formation and interaction with AM fungi in the actinorhizal tree Casuarina glauca and is also able to restore both nodulation and AM symbioses in a Medicago truncatula ccamk mutant. Besides, we expressed auto-active CgCCaMK lacking the auto-inhibitory/CaM domain in two actinorhizal species: C. glauca (Casuarinaceae), which develops an intracellular infection pathway, and Discaria trinervis (Rhamnaceae) which is characterized by an ancestral intercellular infection mechanism. In both species, we found induction of nodulation independent of Frankia similar to response to the activation of CCaMK in the rhizobia-legume symbiosis and conclude that the regulation of actinorhiza organogenesis is conserved regardless of the infection mode. It has been suggested that rhizobial and actinorhizal symbioses originated from a common ancestor with several independent evolutionary origins. Our findings are consistent with the recruitment of a similar genetic pathway governing rhizobial and Frankia nodule organogenesis.

Parent-of-origin-dependent gene expression resulting from genomic imprinting plays an important role in modulating complex traits ranging from developmental processes to cognitive abilities and associated disorders. However, while gene-targeting techniques have allowed for the identification of imprinted loci, very little is known about the contribution of imprinting to quantitative variation in complex traits. Most studies, furthermore, assume a simple pattern of imprinting, resulting in either paternal or maternal gene expression; yet, more complex patterns of effects also exist. As a result, the distribution and number of different imprinting patterns across the genome remain largely unexplored. We address these unresolved issues using a genome-wide scan for imprinted quantitative trait loci (iQTL) affecting body weight and growth in mice using a novel three-generation design. We identified ten iQTL that display much more complex and diverse effect patterns than previously assumed, including four loci with effects similar to the callipyge mutation found in sheep. Three loci display a new phenotypic pattern that we refer to as bipolar dominance, where the two heterozygotes are different from each other while the two homozygotes are identical to each other. Our study furthermore detected a paternally expressed iQTL on Chromosome 7 in a region containing a known imprinting cluster with many paternally expressed genes. Surprisingly, the effects of the iQTL were mostly restricted to traits expressed after weaning. Our results imply that the quantitative effects of an imprinted allele at a locus depend both on its parent of origin and the allele it is paired with. Our findings also show that the imprinting pattern of a locus can be variable over ontogenetic time and, in contrast to current views, may often be stronger at later stages in life.