Strontium-driven physiological to pathological transition of bone-like architecture: A dose-dependent investigation.

Whilst strontium (Sr2+) is widely investigated for treating osteoporosis, it is also related to mineralization disorders such as rickets and osteomalacia. In order to clarify the physiological and pathological effects of Sr2+ on bone biomineralization , we performed a dose-dependent investigation in bone components using a 3D scaffold that displays the hallmark features of bone tissue in terms of composition (osteoblast, collagen, carbonated apatite) and architecture (mineralized collagen fibrils hierarchically assembled into a twisted plywood geometry). As the level of Sr2+ is increased from physiological-like to excess, both the mineral and the collagen fibrils assembly are destabilized, leading to a drop in the Young modulus, with strong implications on pre-osteoblastic cell proliferation. Furthermore, the microstructural and mechanical changes reported here correlate with that observed in bone-weakening disorders induced by Sr2+ accumulation, which may clarify the paradoxical effects of Sr2+ in bone mineralization. More generally, our results provide physicochemical insights into the possible effects of inorganic ions on the assembly of bone extracellular matrix and may contribute to the design of safer therapies for treating osteoporosis. STATEMENT OF SIGNIFICANCE: Physiological-like (10% Sr2+) and excess accumulation-like (50% Sr2+) doses of Sr2+ are investigated in 3D biomimetic assemblies possessing the high degree of organization found in the extracellular of bone. Above the physiological dose, the organic and inorganic components of the bone-like scaffold are destabilized, resulting in impaired cellular activity, which correlates with bone-weakening disorders induced by Sr2+.

Nanoscale Multimodal Analysis of Sensitive Nanomaterials by Monochromated STEM-EELS in Low-Dose and Cryogenic Conditions.

Scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS) provides spatially resolved chemical information down to the atomic scale. However, studying radiation-sensitive specimens such as organic-inorganic composites remains extremely challenging. Here, we analyzed metal-organic framework nanoparticles (nanoMOFs) at low-dose (10 e-/Å2) and liquid nitrogen temperatures, similar to cryo-TEM conditions usually employed for high-resolution imaging of biological specimens. Our results demonstrate that monochromated STEM-EELS enables damage-free analysis of nanoMOFs, providing in a single experiment, signatures of intact functional groups comparable with infrared, ultraviolet, and X-ray data, with an energy resolution down to 7 meV. The signals have been mapped at the nanoscale (<10 nm) for each of these energy spectral ranges, including the chemical features observed for high energy losses (X-ray range). By controlling beam irradiation and monitoring spectral changes, our work provides insights into the possible pathways of chemical reactions occurring under electron exposure. These results demonstrate the possibilities for characterizing at the nanoscale the chemistry of sensitive systems such as organic and biological materials.

Nanoscale Analysis of the Structure and Composition of Biogenic Calcite Reveals the Biomineral Growth Pattern.

The vast majority of calcium carbonate biocrystals differ from inorganic crystals in that they display a patent nanoroughness consisting of lumps of crystalline material (calcite/aragonite) surrounded by amorphous pellicles. Scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS) was used to map the calcite secreted by a barnacle chemically and structurally with ultrahigh resolution (down to 1 nm). The material is composed of irregular lumps of calcite (up to two hundred nm in diameter) surrounded by relatively continuous cortexes (up to 20 nm thick) of amorphous calcium carbonate (ACC) and/or nanocalcite plus biomolecules, with a surplus of calcium relative to carbonate. We develop a model by which the separation of the crystalline and amorphous phases takes place upon crystallization of the calcite from a precursor ACC. The organic biomolecules are expelled from the crystal lattice and concentrate in the form of pellicles, where they stabilize minor amounts of ACC/nanocalcite. In this way, we change the previously established conception of biomineral structure and growth.

Short-term outcomes by chronic betablocker treatment in patients presenting to emergency departments with acute heart failure: BB-EAHFE.

AIMS: To evaluate the association between chronic treatment with betablockers (BB) and the severity of decompensation and short-term outcomes of patients with acute heart failure (AHF). METHODS AND RESULTS: We consecutively included all patients presenting with AHF to 45 Spanish emergency departments (ED) during six different time-periods between 2007 and 2018. Patients were stratified according to whether they were on chronic treatment with BB at the time of ED consultation. Those receiving BB were compared (adjusted odds ratio-OR-with 95% confidence interval-CI-) with those not receiving BB group in terms of in-hospital and 7-day all-cause mortality, need for hospitalization, and prolonged length of stay (≥7 days). Among the 17 923 recruited patients (median age: 80 years; 56% women), 7795 (43%) were on chronic treatment with BB. Based on the MEESSI-AHF risk score, those on BB were at lower risk. In-hospital mortality was observed in 1310 patients (7.4%), 7-day mortality in 765 (4.3%), need for hospitalization in 13 428 (75.0%), and prolonged length of stay (43.3%). After adjustment for confounding, those on chronic BB were at lower risk for in-hospital all-cause mortality (OR = 0.85, 95% CI = 0.79-0.92, P < 0.001); 7-day all-cause mortality (OR = 0.77, 95% CI = 0.70-0.85, P < 0.001); need for hospitalization (OR = 0.89, 95% CI = 0.85-0.94, P < 0.001); prolonged length of stay (OR = 0.90, 95% CI = 0.86-0.94, P < 0.001). A propensity matching approach yielded consistent findings. CONCLUSION: In patients presenting to ED with AHF, those on BB had better short-term outcomes than those not receiving BB.

Inorganic phosphate in growing calcium carbonate abalone shell suggests a shared mineral ancestral precursor.

The presence of phosphate from different origins (inorganic, bioorganic) is found more and more in calcium carbonate-based biominerals. Phosphate is often described as being responsible for the stabilization of the transient amorphous calcium carbonate phase. In order to specify the composition of the mineral phase deposited at the onset of carbonated shell formation, the present study investigates, down to the nanoscale, the growing shell from the European abalone Haliotis tuberculata, using a combination of solid state nuclear magnetic resonance, scanning transmission electron microscope and spatially-resolved electron energy loss spectroscopy techniques. We show the co-occurrence of inorganic phosphate with calcium and carbonate throughout the early stages of abalone shell formation. One possible hypothesis is that this first-formed mixed mineral phase represents the vestige of a shared ancestral mineral precursor that appeared early during Evolution. In addition, our findings strengthen the idea that the final crystalline phase (calcium carbonate or phosphate) depends strongly on the nature of the mineral-associated proteins in vivo.

Nanoscale Analysis of Randall's Plaques by Electron Energy Loss Spectromicroscopy: Insight in Early Biomineral Formation in Human Kidney.

Idiopathic kidney stones originate mainly from calcium phosphate deposits at the tip of renal papillae, known as Randall's plaques (RPs), also detected in most human kidneys without stones. However, little is known about the mechanisms involved in RP formation. The localization and characterization of such nanosized objects in the kidney remain a real challenge, making their study arduous. This study provides a nanoscale analysis of the chemical composition and morphology of incipient RPs, characterizing in particular the interface between the mineral and the surrounding organic compounds. Relying on data gathered from a calculi collection, the morphology and chemical composition of incipient calcifications in renal tissue were determined using spatially resolved electron energy-loss spectroscopy. We detected microcalcifications and individual nanocalcifications found at some distance from the larger ones. Strikingly, concerning the smaller ones, we show that two types of nanocalcifications coexist: calcified organic vesicles and nanometric mineral granules mainly composed of calcium phosphate with carbonate in their core. Interestingly, some of these nanocalcifications present similarities with those reported in physiological bone or pathological cardiovascular biominerals, suggesting possible common formation mechanisms. However, the high diversity of these nanocalcifications suggests that several mechanisms may be involved (nucleation on a carbonate core or on organic compounds). In addition, incipient RPs also appear to present specific features at larger scales, revealing secondary calcified structures embedded in a fibrillar organic material. Our study proves that analogies exist between physiological and pathological biominerals and provides information to understand the physicochemical processes involved in pathological calcification formation.

ABCC6 Deficiency Promotes Development of Randall Plaque.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is a genetic disease caused by mutations in the ABCC6 gene that result in low pyrophosphate levels and subsequent progressive soft tissue calcifications. PXE mainly affects the skin, retina, and arteries. However, many patients with PXE experience kidney stones. We determined the prevalence of this pathology in patients with PXE and examined the possible underlying mechanisms in murine models. METHODS: We conducted a retrospective study in a large cohort of patients with PXE and analyzed urine samples and kidneys from Abcc6-/- mice at various ages. We used Yasue staining, scanning electron microscopy, electron microscopy coupled to electron energy loss spectroscopy, and Fourier transform infrared microspectroscopy to characterize kidney calcifications. RESULTS: Among 113 patients with PXE, 45 (40%) had a past medical history of kidney stones. Five of six computed tomography scans performed showed evidence of massive papillary calcifications (Randall plaques). Abcc6-/- mice spontaneously developed kidney interstitial apatite calcifications with aging. These calcifications appeared specifically at the tip of the papilla and formed Randall plaques similar to those observed in human kidneys. Compared with controls, Abcc6-/- mice had low urinary excretion of pyrophosphate. CONCLUSIONS: The frequency of kidney stones and probably, Randall plaque is extremely high in patients with PXE, and Abcc6-/- mice provide a new and useful model in which to study Randall plaque formation. Our findings also suggest that pyrophosphate administration should be evaluated for the prevention of Randall plaque and kidney stones.

Ligand-induced twisting of nanoplatelets and their self-assembly into chiral ribbons.

The emergence of chirality is a central issue in chemistry, materials science, and biology. In nanoparticle assemblies, chirality has been shown to arise through a few different processes, but chiral organizations composed of plate-like nanoparticles, a class of material under scrutiny due to their wide applicative potential, have not yet been reported. We show that ribbons of stacked board-shaped cadmium selenide (CdSe) nanoplatelets (NPLs) twist upon the addition of oleic acid ligand, leading to chiral ribbons that reach several micrometers in length and display a well-defined pitch of ~400 nm. We demonstrate that the chirality originates from surface strain caused by the ligand because isolated NPLs in dilute solution undergo a transition from a flat to a twisted shape as the ligand coverage increases. When the platelets are closely stacked within ribbons, the individual twist propagates over the whole ribbon length. These results show that a ligand-induced mechanical stress can strongly distort thin NPLs and that this stress can be expressed at a larger scale, paving the way to stress engineering in assemblies of nanocrystals. Such a structural change resulting from a simple external stimulus could have broad implications for the design of sensors and other responsive materials.

Bacteriophage-host interactions leading to genome internalization.

Bacteriophage infection is initiated by binding of the virion to a specific receptor located on the host surface. The genome is then released from the capsid and delivered to the host cytoplasm. Our knowledge of these early steps of infection has recently improved. The three-dimensional structure of numerous receptor binding proteins of tailed phages has been solved. Cryo-electron tomography has allowed characterization of the phage-host interactions in a cellular context and at nanometric resolution. The localization and motions of fluorescently labelled phages, receptors and viral DNA were monitored on individual bacteria. Altogether these approaches have revealed the intricacy of these early events and emphasize the link between infection and microbial architecture.

DNA condensed by protamine: a "short" or "long" polycation behavior.

Using centrifugation assay and light scattering measurements, we study the condensation of DNA by the salmon protamine, a highly basic protein carrying 21 positive charges out of 30 amino acids, in the presence of a high amount of monovalent salt. The DNA condensation is followed by a macroscopic phase separation. It occurs while a large amount of polycations remains freely diffusing in the bulk. A similar behavior was described before for small multivalent ions in diluted DNA solution in a lower salt range. Sensitivity to the salt is however amplified when increasing the charge of polycations. Indeed, a high power-law dependence is observed here with an exponent 11. This variation agrees with the power-law dependence that characterizes the binding of small polycations to DNA. In other words, we show that protamines behave like small polycations in the diluted DNA-high salt regime, while they behave like other large polycations in the diluted DNA-low salt regime as shown in a previous study. In addition, instead of the classical view where binding of polycations to DNA is supposed to trigger DNA condensation in low and moderate salt conditions, we propose that, under high salt conditions, the potential presence of a DNA dense phase triggers the binding of protamines to DNA.

Pressure built by DNA packing inside virions: enough to drive DNA ejection in vitro, largely insufficient for delivery into the bacterial cytoplasm.

Tailed bacteriophage particles carry DNA highly pressurized inside the capsid. Challenge with their receptor promotes release of viral DNA. We show that addition of the osmolyte polyethylene glycol (PEG) has two distinct effects in bacteriophage SPP1 DNA ejection. One effect is to inhibit the trigger for DNA ejection. The other effect is to exert an osmotic pressure that controls the extent of DNA released in phages that initiate ejection. We carried out independent measurements of each effect, which is an essential requirement for their quantitative study. The fraction of phages that do not eject increased linearly with the external osmotic pressure. In the remaining phage particles ejection stopped after a defined amount of DNA was reached inside the capsid. Direct measurement of the size of non-ejected DNA by gel electrophoresis at different PEG concentrations in the latter sub-population allowed determination of the external osmotic pressure that balances the force powering DNA exit (47 atm for SPP1 wild-type). DNA exit stops when the ejection force mainly due to repulsion between DNA strands inside the SPP1 capsid equalizes the force resisting DNA insertion into the PEG solution. Considering the turgor pressure in the Bacillus subtilis cytoplasm the energy stored in the tight phage DNA packing is only sufficient to power entry of the first 17% of the SPP1 chromosome into the cell, the remaining 83% requiring application of additional force for internalization.

A kinetic analysis of DNA ejection from tailed phages revealing the prerequisite activation energy.

All tailed bacteriophages follow the same general scheme of infection: they bind to their specific host receptor and then transfer their genome into the bacterium. DNA translocation is thought to be initiated by the strong pressure due to DNA packing inside the capsid. However, the exact mechanism by which each phage controls its DNA ejection remains unknown. Using light scattering, we analyzed the kinetics of in vitro DNA release from phages SPP1 and lambda (Siphoviridae family) and found a simple exponential decay. The ejection characteristic time was studied as a function of the temperature and found to follow an Arrhenius law, allowing us to determine the activation energy that governs DNA ejection. A value of 25-30 kcal/mol is obtained for SPP1 and lambda, comparable to the one measured in vitro for T5 (Siphoviridae) and in vivo for T7 (Podoviridae). This suggests similar mechanisms of DNA ejection control. In all tailed phages, the opening of the connector-tail channel is needed for DNA release and could constitute the limiting step. The common value of the activation energy likely reflects the existence for all phages of an optimum value, ensuring a compromise between efficient DNA delivery and high stability of the virus.

A propósito de un caso: el derecho a la confidencialidad / A case report: the right to confidentiality

• El secreto profesional y la confidencialidad de los datos siempre han estado unidos, entreotros, tanto a la Medicina como a la Enfermería. Estas cuestiones, de ámbito ético-jurídico,han ido variando con el paso del tiempo en función de los cambios que se han producido enla sociedad, el desarrollo de la Sanidad y la consolidación de los principios de intimidad y privacidadcomo derechos del individuo, así como la importancia de la libertad y la autonomía dela persona frente al bien público o colectivo.• En el ámbito de la relación clínica, esta nueva visión hace que se replanteen las conviccionessobre las informaciones y los datos que se conocen en el ejercicio de la profesión y que debenreservarse al acceso de otros. No es fácil delimitar en nuestra sociedad cuál es la frontera delámbito de lo íntimo, es decir, de lo privado y lo público de las personas cuando se trata de revelarinformación respecto a enfermedades que pueden poner en riesgo a terceros.• Así pues, cuando surgen conflictos entre los deseos de los afectados de no comunicar su diagnósticoa los familiares, a los que están poniendo en riesgo, y el deber de los sanitarios de proteger la saludde la comunidad y, además, de guardar el secreto profesional, una alternativa de lo más oportunapuede ser ponerlo en conocimiento de los Comités de Ética de los centros asistenciales paraque, valorando cada caso particular, puedan sugerir las recomendaciones más adecuadas, desde elconocimiento y el consenso, a los profesionales que se encuentran con ese conflicto moral

• Professional secret and data confidentiality have always walked hand in hand, among other aspects,to both medicine and nursing. These issues, of an ethical and legal nature, have been changing overtime, depending on the changes that have taken place in society, in the development of healthcare,and in the consolidation of intimacy and privacy principles as rights of the individual, as well as theimportance of freedom and autonomy of the person against public or collective wellness.• In a clinical relationship setting, this new vision makes us look at our convictions on the informationand data that are known to us in the practice of the profession and that must be restrictedto others by others. It is not easy to delimit in our society where the borderline lies inthe personal arena; that is, what the private or what the public information of an individual is,when it comes to reveal information regarding diseases that might endanger third parties.• The conflict arises when the wish of the affected individuals is not to inform their relatives abouttheir diagnosis -whom they might be putting at risk- and the duty clinicians have of protecting thehealth of the community and more importantly to keep professional secret. A very convenient alternativeto solve this dilemma would be to inform the Ethics Committees of the institutions ofthe actual insight of the situation. These committees would have the opportunity to evaluate eachparticular case enabling them to suggest the most adequate course of action based on a soundknowledge and consensus to the professionals that are faced with such moral conflict

DNA ejection from bacteriophage T5: analysis of the kinetics and energetics.

DNA ejection from bacteriophage T5 can be passively driven in vitro by the interaction with its specific host receptor. Light scattering was used to determine the physical parameters associated with this process. By studying the ejection kinetics at different temperatures, we demonstrate that an activation energy of the order of 70 k(B)T must be overcome to allow the complete DNA ejection. A complex shape of the kinetics was found whatever the temperature. This shape may be actually understood using a phenomenological model based on a multistep process. Passing from one stage to another requires the mentioned thermal activation of pressurized DNA inside the capsids. Both effects contribute to shorten or to lengthen the pause time between the different stages explaining why the T5 DNA ejection is so slow compared to other types of phage.

Channeling phage DNA through membranes: from in vivo to in vitro.

We discuss current models of phage DNA transport through membranes. We present results that attempt to answer the following questions: is there a single mechanism of transport for all types of phage? is DNA transported as a free molecule or in association with proteins? what is the driving force for transport?