The DNA Methyltransferase DMAP1 is Required for Tissue Maintenance and Planarian Regeneration

The precise regulation of transcription is required for embryonic development, adult tissue turnover, and regeneration. Epigenetic modifications play a crucial role in orchestrating and regulating the transcription of genes. These modifications are important in the transition of pluripotent stem cells and their progeny. Methylation, a key epigenetic modification, influences gene expression through changes in histone tails and direct DNA methylation. Work in different organisms has shown that the DNA methyltransferase-1-associated protein (DMAP1) may associate with other molecules to repress transcription through DNA methylation. Thus, DMAP1 is a versatile protein implicated in a myriad of events, including pluripotency maintenance, DNA damage repair, and tumor suppression. While DMAP1 has been extensively studied in vitro, its complex regulation in the context of the adult organism remains unclear. To gain insights into the possible roles of DMAP1 at the organismal level, we used planarian flatworms that possess remarkable regenerative capabilities driven by pluripotent stem cells called neoblast. Our findings demonstrate the evolutionary conservation of DMAP1 in the planarian Schmidtea mediterranea. Functional disruption of DMAP1 through RNA interference revealed its critical role in tissue maintenance, neoblast differentiation, and regeneration in S. mediterranea. Moreover, our analysis unveiled a novel function for DMAP1 in regulating cell death in response to DNA damage and influencing the expression of axial polarity markers. Our findings provide a simplified paradigm for studying DMAP1's epigenetic regulation in adult tissues.

Connecting the branches of multistable non-Euclidean origami by crease stretching

Non-Euclidean origami is a promising technique for designing multistable deployable structures folded from nonplanar developable surfaces. The impossibility of flat foldability inherent to non-Euclidean origami results in two disconnected solution branches each with the same angular deficiency but opposite handedness. We show that these regions can be connected via "crease stretching," wherein the creases exhibit extensibility in addition to torsional stiffness. We further reveal that crease stretching acts as an energy storage method capable of passive deployment and control. Specifically, we show that in a Miura-Ori system with a single stretchable crease, this is achieved via two unique, easy to realize, equilibrium folding pathways for a certain wide set of parameters. In particular, we demonstrate that this connection mostly preserves the stable states of the non-Euclidean system, while resulting in a third stable state enabled only by the interaction of crease torsion and stretching. Finally, we show that this simplified model can be used as an efficient and robust tool for inverse design of multistable origami based on closed-form predictions that yield the system parameters required to attain multiple, desired stable shapes. This facilitates the implementation of multistable origami for applications in architecture materials, robotics, and deployable structures.

Multistable bioinspired origami with reprogrammable self-folding

Origami has emerged as a design paradigm to realize morphing structures with rich kinematic and mechanical properties. Biological examples augment the potential design space by suggesting intriguing routes for achieving self-folding from architected materials. We introduce a class of multistable self-folding origami adaptable after fabrication inspired by the earwig wing. This is achieved by designing bilayer creases that display anisotropic shrinkage in response to external stimulation, enabling a mechanism for prestrain adaptation. We establish a bilayer model for stretchable straight and trapezoidal (β) creases to generate bistable origami structures. We adapt the topology of the structure’s energy landscapes by tuning the fold prestrain level as a function of the stimulation time. The proposed method and model allows for converting flat sheets with arranged facets and prestrained mountain-valley creases into self-folding multistable structures. Introducing multistability from self-folding avoids ambiguous folding branches present in the rich configuration space at the flat state. The obtained crease prestrain programming is leveraged to manufacture a biomimetic earwig wing featuring the complex crease pattern, structural stability and rapid closure of the biological counterpart. The presented method provides a route for encoding prestrain in self-folding origami, the multistability of which is adaptable after fabrication.

Restoration of DNA integrity and cell cycle by electric stimulation in planarian tissues damaged by ionizing radiation

Exposure to high levels of ionizing γ-radiation leads to irreversible DNA damage and cell death. Here, we establish that exogenous application of electric stimulation enables cellular plasticity to reestablish stem cell activity in tissues damaged by ionizing radiation. We show that sub-threshold direct current stimulation (DCS) rapidly restores pluripotent stem cell populations previously eliminated by lethally γ-irradiated tissues of the planarian flatworm Schmidtea mediterranea. Our findings reveal that DCS enhances DNA repair, transcriptional activity, and cell cycle entry in post-mitotic cells. These responses involve rapid increases in cytosolic [Ca2+] through the activation of L-type Cav channels and intracellular Ca2+ stores leading to the activation of immediate early genes and ectopic expression of stem cell markers in postmitotic cells. Overall, we show the potential of electric current stimulation to reverse the damaging effects of high dose γ-radiation in adult tissues. Furthermore, our results provide mechanistic insights describing how electric stimulation effectively translates into molecular responses capable of regulating fundamental cellular functions without the need for genetic or pharmacological intervention.

Analysis of DNA Double-Stranded Breaks Using the Comet Assay in Planarians

Comet assay provides the opportunity to detect and characterize DNA strand breaks. Cellular lysing followed by embedding in agarose slide is used to visualize under an electrical current migration patterns corresponding to DNA fragments of different sizes. Here we describe the process of detecting and characterizing DNA damage by Comet assay on planarians, which is a model organism commonly used to understand the process of whole-body regeneration, stem cell regulation, and adult tissue maintenance.

P3825Long-term prognostic value of growth differentiation factor-15 in acute coronary syndrome

Introduction

Biomarkers plays a critical role in diagnostic, prognostication, and decision-making in cardiovascular medicine. Growth differentiation factor-15 (GDF-15) has been reported as a potential biomarker in acute coronary syndrome (ACS). However, there is limited data on the long-term prognostic value after an ACS.

Purpose

To study the long-term prognostic value of GDF-15 in ACS.

Methods

We included patients with ACS who underwent coronary angiography. During angiography an arterial blood sample was collected. Plasma GDF-15 were measured and clinical data and long-term events were obtained. As previously reported, risk categories were defined as low risk (<1200ng/L), intermediate (1200–1800ng/L) and high risk (>1800ng/L). Incremental prognostic value of GDF-15 for all-cause death was assessed on top of a clinical model (GRACE score, LVEF<40% and age).

Results

A total of 358 patients were included; 157 as a low risk, 85 as an intermediate and 116 as a high risk. The median (IQR) age was 65 (56–74) years and 27.4% were female. Of all patients, 61.5% were admitted with non-ST-elevation myocardial infarction, 24.0% with ST-elevation myocardial infarction and 14.5% with unstable angina. Higher values of GDF-15 were consistently associated with an increased prevalence of cardiovascular risk factors. During 6 years of follow-up 54 patients died. Of those patients, 7 (4.5%) had values of GDF-15 below 1200ng/L, 6 (7.1%) between 1200–1800ng/L and 41 (35.3%) above 1800ng/L. After adjustment for a multivariate Cox regression model, GDF-15 >1800ng/L were independently associated with all-cause death (HR 4.5; 95% CI 1.8–11.6; p=0.002) and the composite of major adverse cardiovascular events (MACE) which were identified as all-cause death, nonfatal MI and heart failure (HR 2.5; 95% CI 1.4–4.4; p=0.001). For long-term all-cause death a significant increase of the c-statistic was seen after addition of GDF-15 to the clinical model 0.871 (95% CI 0.817–0.924; p=0.019) as well as net reclassification improvement (0.769; 95% CI 0.487–1.051; p<0.001) and integrated discrimination improvement (0.117; 95% CI 0.062–0.172; p<0.001). Of 18 events of heart failure, 17 occurred in patients with GDF>1800ng/L. A multivariate competing risk model showed a significant association between GDF-15>1800ng/L and incidence of heart failure (adjusted HR 30.8; 95% CI 4.1–231.5; p=0.001) but non-significant association were found for myocardial infarction.

KM figures and all-cause death ROC curve

Conclusions

In the setting of ACS GDF-15 can predict long-term all-cause death, MACE and heart failure and provides incremental prognostic value beyond traditional risks factors in the long-term all-cause death.

P6437Growth differentiation factor-15 and stromal cell-derived factor-1 as long-term prognosis biomarkers in acute coronary syndrome

Introduction

After an acute coronary syn bdrome (ACS) patients are at high risk of cardiovascular morbidity and mortality. In this scenario, Growth differentiation factor-15 (GDF-15) and Stromal cell derived factor-1 (SDF-1) has been reported as potential biomarkers in ACS. However, there is limited data about their combined use in long-term prognosis.

Purpose

To study the long-term prognostic value of GDF-15 and SDF-1 in ACS.

Methods

We included patients with ACS who underwent coronary angiography. During angiography an arterial blood sample was collected. Plasma SDF-1 and GDF-15 were measured and clinical data and long-term events were obtained. The cut-off point of SDF-1 and GDF-15 was identified individually by receiver operating characteristic curves. Patients were classified into 3 groups: 1) both biomarkers below cut-off points; 2) only one biomarker above cut-off points; 3) both biomarkers above cut-off points.

Results

A total of 238 patients were included. The median (IQR) age was 64 (55–74) year and 27.3% were female. Of all patients, 60.9% were admitted with non-ST-elevation myocardial infarction, 22.7% with ST-elevation myocardial infarction and 16.4% with unstable angina. The cut-off point of SDF-1 was 3283.5pg/mL and GDF-15 was 1849ng/L. A total of 127 patients were in group 1, 64 in group 2 and 47 in group 3. Group 3 patients were associated with older age, hypertension, dyslipidemia, diabetes mellitus and history of myocardial infarction (MI), stroke, chronic kidney disease and peripheral artery disease. Besides, they were more likely to have left ventricular dysfunction (ejection fraction <40%) and significant three vessels stenosis. During 6.5 years of follow-up 8 patients died (6.3%) in group 1, 7 patients died (10.9%) in group 2 and 25 patients died (53.2%) in group 3 (Figure 1). Multivariate Cox analysis showed that high levels of SDF-1 and GDF-15 (group 3) were an independent predictor of all-cause death (HR 5.8; 95% CI 2.4 - 14.1; p<0.001) and the composite of major adverse cardiovascular events (MACE) which were identified as all-cause death, nonfatal MI and heart failure (HR 3.9; 95% CI 2.1 - 7.3; p<0.001). During follow-up 1 patient had heart failure in group 1 (0.8%), 3 patients (4.7%) in group 2 and 9 patients (19.1%) in group 3. Despite the low number of events of heart failure, the multivariate competing risks regression showed association between group 3 and heart failure during follow-up (HR 28.0; 95% CI 3.5 - 225.2; p=0.002). Higher levels of SDF-1 and GDF-15 (group 3) were not associated with new MI in multivariate competing risks regression. Regarding group 2, all multivariate analyses were non-significant.

Cumulative survival and incidence curves

Conclusions

Higher values of combined GDF-15 and SDF-1 are an excellent predictor of all-cause death, MACE and heart failure in long-term follow-up of patients with ACS. The combined use of SDF-1 and GDF-15 may be useful in long-term ACS prognosis.

Metal organic frameworks based on bioactive components

This review highlights the latest advances of Metal Organic Frameworks (MOFs) in the promising biomedical domain, from their synthesis to their biorelated activities.

One-pot preparation of a novel CO-releasing material based on a CO-releasing molecule@metal–organic framework system

A hierarchical micro-mesoporous metal–organic framework has been used as a platform of a photoactivable CO-prodrug to prepare a novel CO-releasing material.

Nonlinear cerebral atrophy patterns across the Alzheimer's disease continuum: impact of APOE4 genotype

The progression of Alzheimer's disease (AD) is characterized by complex trajectories of cerebral atrophy that are affected by interactions with age and apolipoprotein E allele ε4 (APOE4) status. In this article, we report the nonlinear volumetric changes in gray matter across the full biological spectrum of the disease, represented by the AD-cerebrospinal fluid (CSF) index. This index reflects the subject's level of pathology and position along the AD continuum. We also evaluated the associated impact of the APOE4 genotype. The atrophy pattern associated with the AD-CSF index was highly symmetrical and corresponded with the typical AD signature. Medial temporal structures showed different atrophy dynamics along the progression of the disease. The bilateral parahippocampal cortices and a parietotemporal region extending from the middle temporal to the supramarginal gyrus presented an initial increase in volume which later reverted. Similarly, a portion of the precuneus presented a rather linear inverse association with the AD-CSF index whereas some other clusters did not show significant atrophy until index values corresponded to positive CSF tau values. APOE4 carriers showed steeper hippocampal volume reductions with AD progression. Overall, the reported atrophy patterns are in close agreement with those mentioned in previous findings. However, the detected nonlinearities suggest that there may be different pathological processes taking place at specific moments during AD progression and reveal the impact of the APOE4 allele.

Development of a variable-radius pinhole SPECT system with a portable gamma camera

OBJECTIVE

To develop a small-animal SPECT system using a low cost commercial portable gamma camera equipped with a pinhole collimator, a continuous scintillation crystal and a position-sensitive photomultiplier tube.

MATERIAL AND METHODS

The gamma camera was attached to a variable radius system, which enabled us to optimize sensitivity and resolution by adjusting the radius of rotation to the size of the object. To investigate the capability of the SPECT system for small animal imaging, the dependence of resolution and calibration parameters on radius was assessed and acquisitions of small phantoms and mice were carried out.

RESULTS

Resolution values, ranging from 1.0mm for a radius of 21.4mm and 1.4mm for a radius of 37.2mm were obtained, thereby justifying the interest of a variable radius SPECT system.

CONCLUSIONS

The image quality of phantoms and animals were satisfactory, thus confirming the usefulness of the system for small animal SPECT imaging.

The effects of aging on dopaminergic neurotransmission: a microPET study of [11C]-raclopride binding in the aged rodent brain

Rodent models are frequently used in aging research to investigate biochemical age effects and aid in the development of therapies for pathological and non-pathological age-related degenerative processes. In order to validate the use of animal models in aging research and pave the way for longitudinal intervention-based animal studies, the consistency of cerebral aging processes across species needs to be evaluated. The dopaminergic system seems particularly susceptible to the aging process, and one of the most consistent findings in human brain aging research is a decline in striatal D2-like receptor (D2R) availability, quantifiable by positron emission tomography (PET) imaging. In this study, we aimed to assess whether similar age effects can be discerned in rat brains, using in vivo molecular imaging with the radioactive compound [(11)C]-raclopride. We observed a robust decline in striatal [(11)C]-raclopride uptake in the aged rats in comparison to the young control group, comprising a 41% decrement in striatal binding potential. In accordance with human studies, these results indicate that substantial reductions in D2R availability can be measured in the aged striatal complex. Our findings suggest that rat and human brains exhibit similar biochemical alterations with age in the striatal dopaminergic system, providing support for the pertinence of rodent models in aging research.

Testosterone stimulates progesterone production and STAR, P450 cholesterol side-chain cleavage and LH receptor mRNAs expression in hen (Gallus domesticus) granulosa cells

The chicken ovary is organized into a hierarchy of yellow yolky follicles that ovulate on successive days. Active or passive immunization of laying hens against testosterone blocks ovulation without affecting follicle development. Testosterone may play a role in pre-ovulatory follicle maturation by stimulating granulosa progesterone production. We assessed whether this stimulus is dose-related and depends on the maturity of the donor follicle, and if it does so by stimulating granulosa cell STAR, P450 cholesterol side-chain cleavage (P450scc), and LH receptor (LHCGR) mRNAs expression. Progesterone production by granulosa cells from F1, F3, and F4 follicles, cultured for 3 h without testosterone was greater in cells collected 11-14 h than 1-4 h after ovulation. These differences in progesterone production were less pronounced after granulosa cells had been cultured for 24 h. Culture of granulosa cells for 3 or 24 h with testosterone (1-100 ng/ml) stimulated progesterone production in cells collected from F4, F3, or F1 follicles 1-4, or 11-14 h after ovulation. Testosterone (0-4000 ng/ml) alone or in combination with LH (0-100 ng/ml) increased progesterone production by F1 granulosa cells, collected 1-4 and 11-14 h after ovulation and cultured for 3 h. Finally, testosterone (10 or 100 ng/ml) increased STAR, P450scc, and LHCGR mRNAs, when added to 3 h cultures of F1 granulosa cells. In conclusion, testosterone stimulates granulosa cell progesterone production in hen pre-ovulatory hierarchical follicles irrespective of maturational state, acting alone or additively with LH. We propose that testosterone promotes granulosa cell maturation to facilitate the pre-ovulatory release of LH.

Evaluation of six pesticides leaching indexes using field data of herbicide application in Casablanca Valley, Chile

A field study was performed to evaluate the accuracy of six pesticide screening leaching indexes for herbicide movement. Adsorption, dissipation and soil movement were studied in a vineyard in a sandy loam soil during 2005 season. Simazine, diuron, pendimethalin, oxyfluorfen and flumioxazin were applied to bare soil at rates commonly used, and their soil concentrations throughout soil profile were determined at 0, 10, 20, 40 and 90 days after application (DAA). Herbicides were subjected to two pluviometric regimens, natural field condition and modified conditions (plus natural rainfall 180 mm). Leaching indexes utilized were: Briggs's Rf, Hamaker's Rf, LEACH, LPI, GUS and LIX. Simazine reached 120 cm, diuron 90 cm, flumioxazin 30 cm soil depth respectively. Pendimethalin and oxyfluorfen were retained up to 5 cm. None of the herbicides leaching was affected by rainfall regimen. Only flumioxazin field dissipation was clearly affected by pluviometric condition. The best representation of the herbicide soil depth movement and leaching below 15 cm soil depth were: Hamaker's Rf < Briggs's Rf < GUS < LPI, < LEACH < LIX. Field results showed a good correlation between herbicides K(d) and their soil depth movement and mass leached below 15 cm soil depth.

Relevance in the Fischer−Tropsch Synthesis of the Formation of Fe−O−Ce Interactions on Iron−Cerium Mixed Oxide Systems

A series of Fe-Ce mixed oxides (95 atom % Fe-5 atom % Ce) has been prepared by different methods: coprecipitation, impregnation, and physical mixture of Ce and Fe oxides. These solids have been tested in the Fischer-Tropsch synthesis. The characterization of the catalytic precursors was carried out by X-ray diffraction (XRD), Raman, Mössbauer, and X-ray photoelectron (XPS) spectroscopic techniques. When the preparation method ensures a microscopic contact between Fe and Ce cations in the solid, several types of Fe-Ce interactions are present in the calcined solids. The interactions take the shape of Fe-O-Ce bridges that can exist either in the hematite-like solid solution or in the interphase between the Fe oxide covered by microcrystals of Ce oxide. In the case of the hematite-like solid solution, Ce(IV) cations are dissolved in the alpha-Fe2O3 network. The promotion by Ce of the catalytic properties observed in the final catalysts can be directly related with the detection of these Fe-O-Ce bridges in the calcined solids. The Ce promotion results in a larger yield to hydrocarbons, a higher production of olefins, and a higher selectivity to medium and large chain hydrocarbons (larger than six carbon atoms). It is proposed that the Ce promotion is due to the presence of Fe0-Ce(III) ensembles in the final catalysts arising from the initial Fe-O-Ce bridges developed in the parent calcined samples.

Ovine serum and pituitary isoforms of luteinising hormone during the luteal phase

The relative abundance of the different isoforms of pituitary and circulating luteinising hormone (LH) in ewes, at different times after the administration of gonadotrophin-releasing hormone (GnRH), during the luteal phase of the oestrous cycle was investigated. Sixteen ewes on Day 9 of their cycle were divided into four groups (n = 4). The control group (T0) received saline solution; the remaining animals received 100 μg GnRH (i.m.) 30, 90 or 180 min (T30, T90 and T180, respectively) before serum and pituitary gland collection. Luteinising hormone polymorphism was analysed by chromatofocusing (pH 10.5–3.5). The LH eluted from each chromatofocusing was grouped on the basis of the following three criteria: (1) according to the pH of elution (pH ≥ 10–3.5); (2) as either a basic (pH ≥ 7.5), neutral (pH 7.4–6.5) and acidic (pH ≤ 6.4) elution of LH of serum and hypophyseal origin; and (3) on the basis of distinct isoforms, of which 10 (A–J) were identifiable in hypophyseal extracts and four (A–D) were found in the serum. In general, the most abundant forms of LH in both the pituitary and serum, at all times, were basic. However, that proportion was greater in hypophyseal extracts (84 ± 3%, 81 ± 4%, 82 ± 3% and 83 ± 2% at T0, T30, T90 and T180, respectively) than in serum (51 ± 5%, 48 ± 10% and 54 ± 6% at T30, T90 and T180, respectively). Neutral and acidic LH made up a larger proportion of the total LH in sera (neutral: 17 ± 4%, 20 ± 6% and 23 ± 3% at T30, T90 and T180, respectively; acidic: 32 ± 8%, 32 ± 11% and 23 ± 6% at T30, T90 and T180, respectively) than in the pituitary extracts (neutral: 4.0 ± 0.7%, 10 ± 4%, 7 ± 2% and 5.0 ± 0.5% at T0, T30, T90 and T180, respectively; acidic: 12 ± 3%, 11 ± 2%, 12 ± 2% and 12 ± 2% at T0, T30, T90 and T180, respectively) at all times. These data reveal that the relative composition of the LH present in the pituitary gland and the LH secreted into the circulation is different, with more neutral and acidic isoforms being secreted. The pattern of circulating LH isoforms changes between 30 and 180 min after GnRH peak induction, with a greater proportion of isoform C (eluting between pH 7.0 and 6.5) at T180 compared with T30 and T90.

Pattern of circulating luteinizing hormone isoforms during the estrous and luteal phases in Holstein heifers

The pattern of distribution of circulating luteinizing hormone (LH) isoforms in cattle during estrus and the luteal phase was investigated. In each stage, the stage of the estrous cycle was synchronized in seven Holstein heifers with a prostaglandin analogue. After estrus was detected, blood samples were taken at 2-h intervals for 24h. In the luteal phase, animals received 250 microg i.v. of GnRH and blood samples were collected every 15 min for 5h. LH concentration in the samples was determined. Samples with the greatest LH concentration in estrus (pre-ovulatory peak) and those collected 60 min after GnRH administration (luteal phase) were analyzed by chromatofocusing, eluted with a pH gradient from 10.5 to 3.5. Eluted LH was grouped into basic (pH > or = 7.5), neutral (pH 7.4-6.5) and acidic isoforms (pH < or = 6.4) as well as by pH unit. In both phases, basic forms were the most abundant, and these were greater (P < 0.05) during the luteal phase (78.4 +/- 4.2%) as compared with during estrus (57.1 +/- 6.2%); the proportion of neutral and acidic isoforms in estrus (13.7 +/- 2.6%; 28.5 +/- 2.8%) was greater (P < 0.05) as compared with the luteal phase (3.0 +/- 0.7; 18.7 +/- 3.4). These results indicate that the relative proportion of LH isoforms secreted by the adenohypophysis differ by stage of estrous cycle. The addition of excess of NaCl to the column modifies the antigen-antibody binding in the RIA, and the proteins eluted are erroneously quantified as LH; this is an artifact of the technique.

The monocyte locomotion inhibitory factor produced by Entamoeba histolytica inhibits induced nitric oxide production in human leukocytes

The monocyte locomotion inhibitory factor, an anti-inflammatory pentapeptide produced by Entamoeba histolytica, inhibits the in vitro production of nitric oxide induced by cytokines (INF-gamma, TNF-alpha) or PMA in human leukocytes. This can be added to the other previously reported functional effects of this factor, such as the inhibition of monocyte locomotion and the synthesis of reactive oxygen intermediates in both monocytes and neutrophils. The decreased nitric oxide production may interfere with the killing of amebas by neutrophils in the early invasive stages of amebiasis, when oxidative mechanisms are used [reactive oxygen and nitrogen intermediates either individually or synergistically via peroxynitrite (ONOO(-))], and in the advanced stages, when both non-oxidative and oxidative (including nitric oxide) mechanisms are employed by macrophages. Diminished nitric oxide production by leukocytes may also contribute to the paucity of late inflammatory components in amebic abscess of the liver and other amebic lesions.