Basement membrane heterogeneity during chick development as shown by tomato (Lycopersicon esculentum) lectin binding

Basement membranes (BMs) constitute a distinct compartment of the extracellular matrix (ECM). All BMs show a similar structural appearance but differ in molecular composition. These variations have critical functional implications. The aim of this study is to establish the pattern of the tomato lectin (Lycopersicon esculentum agglutinin--LEA) binding sites in the BMs of the developing chick embryo (stages 4-21, Hamburger and Hamilton, 1951) in order to achieve a better understanding of the molecular heterogeneity of BMs. The study was performed with transmission electron microscopy (TEM) histochemistry, and confocal laser microscopy. TEM showed that LEA bound to the lamina densa and to the lamina fibroreticularis of the BMs. Through the period studied, most of the LEA binding appeared in the ectodermal BM and its derivatives. In the limb bud, LEA binding to the ectoderm BM was more intense in the ventral half than in the dorsal half. Furthermore, LEA allowed the early (HH16) detection of the transverse fibrillar tracts. In the lens and in the inner ear primordium, the BMs were LEA positive through the placode and cup stages. The binding was progressively reduced through the vesicle stage. The BMs of the olfactory primordium, and of the Rathke's pouch were positive. In contrast, the BMs of the developing central nervous system were negative. The BMs of both the paraxial and the lateral plates of the mesoderm were negative, whereas the notochord and the BM of the Wolffian duct were positive. The endodermal BM and its derivatives were negative. The ECM located between the fusing endocardial tubes, and the BM of the fusion zone of the paired aortae, were positive. This suggested an active role of the LEA-positive glycoproteins in the fusion of endothelia. Our results show the heterogeneity of the chick embryo BMs during development. In addition, LEA constitutes an excellent marker for the primordial germ cells

Acinetobacter Baumannii Maintains Its Virulence After Long-Time Starvation

Acinetobacter baumannii is a cause of healthcare-associated infections. Although A. baumannii is an opportunistic pathogen, its infections are notoriously difficult to treat due to intrinsic and acquired antimicrobial resistance, often limiting effective therapeutic options. A. baumannii can survive for long periods in the hospital environment, particularly on inanimate surfaces. Such environments may act as a reservoir for cross-colonization and infection outbreaks and should be considered a substantial factor in infection control practices. Moreover, clothing of healthcare personnel and gadgets may play a role in the spread of nosocomial bacteria. A link between contamination of hospital surfaces and A. baumannii infections or between its persistence in the environment and its virulence has not yet been established. Bacteria under stress (i.e., long-term desiccation in hospital setting) could conserve factors that favor infection. To investigate whether desiccation and/or starvation may be involved in the ability of certain strains of A. baumannii to retain virulence factors, we have studied five well-characterized clinical isolates of A. baumannii for which survival times were determined under simulated hospital conditions. Despite a considerable reduction in the culturability over time (up to 88% depending on strain and the condition tested), some A. baumannii strains were able to maintain their ability to form biofilms after rehydration, addition of nutrients, and changing temperature. Also, after long-term desiccation, several clinical strains were able to grow in the presence of non-immune human serum as fine as their non-stressed homologs. Furthermore, we also show that the ability of bacterial strains to kill Galleria mellonella larvae does not change although A. baumannii cells were stressed by long-term starvation (up to 60 days). This means that A. baumannii can undergo a rapid adaptation to both the temperature shift and nutrients availability, conditions that can be easily found by bacteria in a new patient in the hospital setting.Research in our laboratory is supported by the Spanish Instituto de Salud Carlos III, Spain (grant PI16/01103 to José Ramos-Vivas) and the Plan Nacional de I+D+i 2008-2011 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD12/0015) - co-financed by European Development Regional Fund "A way to achieve Europe" ERDF. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Functional, structural, and molecular remodelling of the goldfish (Carassius auratus) heart under moderate hypoxia

The goldfish (Carassius auratus) is known for its physiologic ability to survive even long periods of oxygen limitation (hypoxia), adapting the cardiac performance to the requirements of peripheral tissue perfusion. We here investigated the effects of short-term moderate hypoxia on the heart, focusing on ventricular adaptation, in terms of hemodynamics and structural traits. Functional evaluations revealed that animals exposed to 4 days of environmental hypoxia increased the hemodynamic performance evaluated on ex vivo cardiac preparations. This was associated with a thicker and more vascularized ventricular compact layer and a reduced luminal lacunary space. Compared to normoxic animals, ventricular cardiomyocytes of goldfish exposed to hypoxia showed an extended mitochondrial compartment and a modulation of proteins involved in mitochondria dynamics. The enhanced expression of the pro-fission markers DRP1 and OMA1, and the modulation of the short and long forms of OPA1, suggested a hypoxia-related mitochondria fission. Our data propose that under hypoxia, the goldfish heart undergoes a structural remodelling associated with a potentiated cardiac activity. The energy demand for the highly performant myocardium is supported by an increased number of mitochondria, likely occurring through fission events.Open access funding provided by Università della Calabria within the CRUI-CARE Agreement. This research was funded by the MIUR (Ministero dell’Istruzione dell’Università e della Ricerca) of Italy (ex 60%). M. F. is supported by PON “Ricerca e Innovazione” 2014–2020, Azione IV.6, “Contratti di ricerca su tematiche Green” (D. M. 1062 del 10.08.2021), C. I.: 1062_R6_GREEN, CUP: H25F21001230004

Identification of human pathological mitral chordae tendineae using polarization-sensitive optical coherence tomography

Defects of the mitral valve complex imply heart malfunction. The chordae tendineae (CTs) are tendinous strands connecting the mitral and tricuspid valve leaflets to the papillary muscles. These CTs are composed of organized, wavy collagen bundles, making them a strongly birefringent material. Disorder of the collagen structure due to different diseases (rheumatic, degenerative) implies the loss or reduction of tissue birefringence able to be characterized with Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT is used to discriminate healthy from diseased chords, as the latter must be excised and replaced in clinical conventional interventions. PS-OCT allows to quantify birefringence reduction in human CTs affected by degenerative and rheumatic pathologies. This tissue optical property is proposed as a diagnostic marker for the identification of degradation of tendinous chords to guide intraoperative mitral valve surgery.Research was funded by Ministerio de Economía, Industria y Competitividad, Gobierno de España, grant numbers FIS2010-19860 (DA2TOI) and TEC2016-76021-C2-2-R (SENSA), Instituto de Salud Carlos III, grant number DTS17-00055 (FUSIODERM), Instituto de Investigación Marqués de Valdecilla (IDIVAL), grant number INNVAL 16/02 (DICUTEN) and INNVAL 18/23 (DAPatOO), University of Cantabria postdoctoral grant, POS-UC-2018-16. Co-funded with FEDER funds

Laterality defect of the heart in non-teleost fish

Dextrocardia is a rare congenital malformation in humans in which most of the heart mass is positioned in the right hemithorax rather than on the left. The heart itself may be normal and dextrocardia is sometimes diagnosed during non-related explorations. A few reports have documented atypical positions of the cardiac chambers in farmed teleost fish. Here, we report the casual finding of a left-right mirrored heart in an 85 cm long wild-caught spiny dogfish (Squalus acanthias) with several organ malformations. Macroscopic observations showed an outflow tract originating from the left side of the ventricular mass, rather than from the right. Internal inspection revealed the expected structures and a looped cavity. The inner curvature of the loop comprised a large trabeculation, the bulboventricular fold, as expected. The junction between the sinus venosus and the atrium appeared normal, only mirrored. MRI data acquired at 0.7 mm isotropic resolution and subsequent 3D-modeling revealed the atrioventricular canal was to the right of the bulboventricular fold, rather than on the left. Spurred by the finding of dextrocardia in the shark, we revisit our previously published material on farmed Adriatic sturgeon (Acipenser naccarii), a non-teleost bony fish. We found several alevins with inverted (left-loop) hearts, amounting to an approximate incidence of 1%-2%. Additionally, an adult sturgeon measuring 90 cm in length showed abnormal topology of the cardiac chambers, but normal position of the abdominal organs. In conclusion, left-right mirrored hearts, a setting that resembles human dextrocardia, can occur in both farmed and wild non-teleost fish.ACKNOWLEDGMENTS. The authors wish to thank A. Domezain, from the Sierra Nevada Fishery at Riofrío, Granada, Spain, for generous access to the sturgeon material. Jaco Hagoort's help in generating the 3D model is much appreciate

Adjusted global antiphospholipid syndrome score (aGAPSS) is useful to predict relapses in patients with retinal vein occlusion

Background A significant proportion of patients with retinal vein occlusion (RVO) are antiphospholipid antibodies (aPL) carriers. Relapsing disease occurs in nearly 10 % of cases and the role of aPL has not been established. The adjusted global antiphospholipid syndrome score (aGAPSS) was developed to assess the risk of clinical events in aPL carriers and its role in the management of RVO patients is unknown. Objective To analyze the values of aGAPSS in a large cohort of patients with RVO and population-based controls, and to assess its usefulness to predict RVO relapses. Methods Case-control study of RVO patients and population-based controls of similar age and sex. We have assessed and compared the aPL profile and the aGAPSS score in patients with and without relapsing disease and controls. Results Four-hundred and seventy-two RVO patients and 346 controls were included. Fifty-seven RVO patients had antiphospholipid syndrome (RVO-APS). Of them, 75.4 % had a high-risk profile compared to 3 % in controls (p = 0.0001). The median aGAPSS values were 8 [7?13], 3 [1?4], and 3 [0?4], in RVO-APS, RVO no-APS, and controls. Nineteen patients had had a recurrence of RVO before inclusion and 8 during the follow-up. APS was more prevalent in relapsing patients. In the adjusted multivariable regression model, the best predictor for RVO recurrence during the follow-up was an aGAPSS score ?6 (OR 5.5, CI95% 1.3?23.7; p = 0.023). Conclusions In patients with RVO, once the control of vascular risk factors has been optimized, the aGAPSS might help to identify those at risk of relapsing disease.Sources of funding: The Camargo Cohort Study was supported by a grant from Instituto de Salud Carlos III (PI21/00532) that could be co-funded by European Union FEDER funds

Failure of digit tip regeneration in the absence of Lmx1b suggests Lmx1b functions disparate from dorsoventral polarity

Mammalian digit tip regeneration is linked to the presence of nail tissue, but a nail-explicit model is missing. Here, we report that nail-less double-ventral digits of DLARM1/2 mutants that lack limb-specific Lmx1b enhancers fail to regenerate. To separate the nail's effect from the lack of dorsoventral (DV) polarity, we also interrogate double-dorsal double-nail digits and show that they regenerate. Thus, DV polarity is not a prerequisite for regeneration, and the nail requirement is supported. Transcriptomic comparison between wild-type and non-regenerative DLARM1/2 mutant blastemas reveals differential upregulation of vascularization and connective tissue functional signatures in wild type versus upregulation of inflammation in the mutant. These results, together with the finding of Lmx1b expression in the postnatal dorsal dermis underneath the nail and uniformly in the regenerative blastema, open the possibility of additional Lmx1b roles in digit tip regeneration, in addition to the indirect effect of mediating the formation of the nail.Acknowledgments: Supported by funds from the Spanish Ministry of Science and Innovation Grant PID2020-114525GB-I00 to M.R. and from the Pathology Research endowment, the S. H. Crook’s Chair to K.C.O. A.C.-I. is supported by Spanish Ministry of Science and Innovation PhD fellowship PRE2018-083421. S.Z. was supported by a PhD fellowship from the Universidad de Cantabria. SHG imaging and analysis was conducted at the Microscopy & Dynamic Imaging Unit, CNIC, ICTS-ReDib, co-funded by MCIN/AEI/10.13039/501100011033. We thank Can Aztekin for critical reading, Irene Mate for technical support, and the Animal Facility of the Universidad de Cantabria for outstanding animal husbandr