Calcium Distribution Research Articles

Calcium affects uranium responses in Arabidopsis thaliana: From distribution to toxicity

Uranium, a heavy metal and primordial radionuclide, is present in surface waters and soils both naturally and due to industrial activities. Uranium is known to be toxic to plants and its uptake and toxicity can be influenced by multiple factors such as pH and the presence of different ions. However, the precise role of the different ions in uranium uptake is not yet known. Here we investigated whether calcium influences uranium uptake and toxicity in the terrestrial plant Arabidopsis thaliana.To this end, A. thaliana plants were exposed to different calcium and uranium concentrations and furthermore, calcium channels were blocked using the calcium channel blocker lanthanum chloride (LaCl3). Fresh weight, relative growth rate, concentration of nutrients and uranium and gene expression of oxidative stress-related genes and calcium transporters were determined in roots and shoots.Calcium affected plant growth and oxidative stress in both control (no uranium) and uranium-exposed plants. In shoots, this was influenced by the total calcium concentration, but not by the different tested uranium concentrations. Uranium in turn did influence calcium uptake and distribution. Uranium-exposed plants grown in a medium with a higher calcium concentration showed an increase in gene expression of NADPH oxidases RBOHC and RBOHE and calcium transporter CAX7 after uranium exposure. In roots, these calcium-dependent responses in gene expression were not observed. This indicates that calcium indeed affects uranium toxicity, but only in shoots. In addition, a clear influence of uranium and LaCl3 (separately and combined) on the expression of calcium transporters was observed.

Deep tilling and localized liming improve soil chemical fertility and sugarcane yield in clayey soils

The selection of an appropriate soil tillage system for improving yields and longevity is an important decision in sugarcane cultivation. In the present study, the effects of different soil tillage systems and methods of applying lime on sugarcane stalk and sugar yield performance as well as soil fertility parameters were evaluated throughout the sugarcane crop cycle. The experiments were established in two locations in April 2015 and conducted until August 2019, corresponding to a total of 4 growing seasons. A field study with a randomized block design was established with four replicates considering 4 treatments: conventional soil tillage system (CT), deep strip-tillage system (DT) and modified deep strip-tillage system (MDT), all with the same lime rate; and a standard treatment (control, CT without liming). Immediately after harvesting plant cane (18 months (mo) after planting), first ratoon (30 mo after planting), second ratoon (42 mo after planting) and third ratoon (54 mo after planting), soil samples were collected from a depth of 0.0–1.00 m, stratified every 0.2 m. Leaf material was sampled during the period of full vegetative growth. Analyses of soil chemical fertility, leaf concentrations of elements, and sugarcane yield components were performed. MDT was found to correct soil acidity most efficiently, mainly due to the positioning of the lime application. Under high aluminum saturation (AS), especially in deeper layers, deep lime placement was more effective and resulted in the best distributions of calcium (Ca2+) and magnesium (Mg2+), the highest base saturation (BS) and the lowest AS compared with the other treatments. Lime application was more important than the tillage system for improving the sucrose concertation and total recoverable sugar (TRS), whereas the tillage system affected the stalk yield and, consequently, the yield of sugar. Compared with DT and CT, the average stalk yield was 4.1% and 9.4% higher, respectively, under MDT at Macatuba and 6.3% and 15.3%, higher, respectively, under MDT at Piraju. Similarly, MDT improved average sugar yield by 3.7% and 10.4% at Macatuba and 6.1% and 16.3% at Piraju. Overall, long-term assessments, which are important for semi-perennial crops like sugarcane, showed that the both deep strip-tillage were most effective.

Water depth determines spatial and temporal phosphorus retention by controlling ecosystem transition and P-binding metal elements

Shallow lakes are more susceptible to eutrophication than deep lakes. The geochemical and biogeochemical mechanisms controlling the vulnerability to eutrophication for deep lakes and shallow lakes remain unknown. Therefore, we investigated the combined Phosphorus (P) retention mechanism with P fractions, water depth, distribution of P-binding metal elements, and macrophytes coverage in a degrading ecosystem of Erhai Lake. We concluded that different mechanisms control the P retention in deep-water areas and shallow-water areas. In shallow areas covered by macrophytes, the biogeochemical process manipulates the P retention by changing the total organic carbon (TOC), calcium (Ca) distributions and turbulence. In deep areas without macrophyte coverage, the aluminum (Al) and iron (Fe) distributions control the P retention by a physicochemical process. Manganese (Mn) was found to be a potential proxy in tracking the kinetic release and readsorb of redox-sensitive P (BD-P) in deep areas. The historical record and core sample indicate that the hydrological engineering induced water depth variation is a vital factor changing the ecosystem of Erhai Lake by forming a large area of intermediate area where macrophytes could only survive at low water level. The uplift of water level in the 1990s gradually changed the ecosystem of Erhai Lake from macrophyte-dominated to algal-macrophyte concomitant that reduced the accumulation of stable P fractions and their binding metals. Macrophytes were capable to preserve P in biomass in the macrophyte-dominated ecosystem, which released 150% and 72% of more labile organic P (NaOH25-nrP) and BD-P in the sediment after the deterioration than before, respectively. Therefore, water depth is a prerequisite to restoring the P preservation capacity of sediment and the macrophyte ecosystem. Further hydraulic engineering projects should consider the effect of water-level-variation-induced ecosystem transition.

Abstract 186: Anatomically Indexed Distributions Of Aortic Calcification In A Reference Population

Introduction: Cardiovascular disease remains the leading cause of death in the United States. Aortic calcification shows strong promise towards preventative screening efforts for cardiovascular risk in clinical and subclinical populations. While still relatively novel, granular distributions of aortic calcium in reference populations are absent from the literature. Methods: All participants of the Reference Analytic Morphomics Population, an approximation of vehicle occupants in the United States, with abdominal scans were considered for this analysis (n=4080). Analytic Morphomics was used to obtain vertebral-indexed anatomical measurements of the aorta and calcium characteristics (area, volume, density, and aortic wall obfuscation). Calcification was specifically identified as regions with a given morphology and pixel value three standard deviations above the defined central lumen zone. Results: Participant mean age was 33 (SD 22.6) and were mostly male (62.6%) due to the prevalence of males involved in trauma. Age and calcification distributions were right skewed among all vertebral levels and highest for the L3-L4 reference levels [~3% wall obfuscation (SD 10.5-11.3)]. Males demonstrated a progressive increase in total calcium volume from the 4 th decade of age, while females had comparatively smaller increases and a dramatic increase in total calcium after the 7 th decade. The largest increases in observed calcium volumes were observed in the 8 th decade for males (~2300 cm 3 ) and 7 th for females (~4500 cm 3 ). Conclusion: Aortic calcium prevalence was higher with reference to lower vertebral levels. Dramatic differential distributions of calcium were observed by age and sex.

Distribution of Coronary Artery Calcium by Age, Sex, and Race Among Patients 30-45 Years Old

BackgroundCoronary artery calcium (CAC) is a measure of atherosclerotic burden and is well-validated for risk stratification in middle- to older-aged adults. Few studies have investigated CAC in younger adults, and there is no calculator for determining age-, sex-, and race-based percentiles among individuals aged <45 years. ObjectivesThe purpose of this study was to determine the probability of CAC >0 and develop age-sex-race percentiles for U.S. adults aged 30-45 years. MethodsWe harmonized 3 datasets—CARDIA (Coronary Artery Risk Development in Young Adults), the CAC Consortium, and the Walter Reed Cohort—to study CAC in 19,725 asymptomatic Black and White individuals aged 30-45 years without known atherosclerotic cardiovascular disease. After weighting each cohort equally, the probability of CAC >0 and age-sex-race percentiles of CAC distributions were estimated using nonparametric techniques. ResultsThe prevalence of CAC >0 was 26% among White males, 16% among Black males, 10% among White females, and 7% among Black females. CAC >0 automatically placed all females at >90th percentile. CAC >0 placed White males at the 90th percentile at age 34 years compared with Black males at age 37 years. An interactive webpage allows one to enter an age, sex, race, and CAC score to obtain the corresponding estimated percentile. ConclusionsIn a large cohort of U.S. adults aged 30-45 years without symptomatic atherosclerotic cardiovascular disease, the probability of CAC >0 varied by age, sex, and race. Estimated percentiles may help interpretation of CAC scores among young adults relative to their age-sex-race matched peers and can henceforth be included in CAC score reporting.

Comparisons of iron ore granulation and sintering performance between horizontal high-shear granulators and drum granulators

Granulation is a key operation unit in preparation of iron ore raw materials. This work presented an experimental study on the iron ore granulation and sintering using a novel horizontal high-shear granulator and a traditional drum granulator. The mixing and granulation performance and the effect of granulation on sintering indicators were analyzed. The results showed that the optimal filling level of the shear granulator was about 9%, which was slightly lower than that of the drum granulator (12%). However, the uniformity, bed permeability and the fracture strength of the granules from the shear granulator were significantly better than those from the drum granulator. Compared with the drum granulator, the shear granulator had better mixing ability in the axial direction, more even distributions of water and calcium and less segregation. For the thick-bed sintering with a height of 900 mm, the sintering indicators in terms of sintering speed, sinter yield, strength and flue composition showed the shear granulator was significantly better than that of the drum granulator.

Atrial Embolization after a Transcatheter Mitral Valve Replacement

Atrial Embolization after a Transcatheter Mitral Valve Replacement

Lipopolysaccharide increases exosomes secretion from endothelial progenitor cells by toll-like receptor 4 dependent mechanism.

Endothelial progenitor cells (EPCs) can exert angiogenic effects by a paracrine mechanism, where exosomes work as an important mediator. Recent studies reported functional expression of toll-like receptor (TLR) 4 on human EPCs and dose-dependent effects of lipopolysaccharide (LPS) on EPC angiogenic properties. To study the effects of TLR4/LPS signaling on EPC-derived exosomes (Exo) and clarify the mechanism, we investigated the role of LPS on exosomes secretion from human EPCs and tested their anti-oxidation/senescence functions. We employed the inhibitors of the plasma membrane Ca2+ -ATPase (PMCA), endoplasmic reticulum Ca2+ -ATPase (ERCA), PLC-IP3 pathway and store-operated calcium entry to assess the effects of LPS on EPC intracellular calcium signalings which critical for exosome secretion. LPS induced the release of Exo in a TLR4-dependent manner in vitro, which effect can be partly abrogated by an membrane-permeable IP 3 R antagonist, 2-aminoethyl diphenylborinate (2-APB), but not PLC inhibitor, U-73122. The LPS can significantly delay the fallback of [Ca2+ ]i after isolating the cellular PMCA activity, and disturb PMCA 1/4 expression. The distribution of elevated intracellular calcium seemed coincident with the development of the multivesicular bodies (MVBs). furthermore, the anti-oxidation/senescence properties of LPS-induced Exo were validated by the senescence-associated β-galactosidase activity assay and reactive oxygen species (ROS) related H2 DCF-DA assay. The mechanism of PMCA downregulation and IP3 R-dependent ER Ca2+ release may contribute to the pro-exosomal effects of LPS on EPCs. This study provides new insights into the potential role of LPS/TLR4 pathway in regulating EPC-derived exosomes, which may help to develop some feasible approach to manipulate the Exo secretion and promote the clinical application of EPCs therapy in future.

Chromosome-scale Cerasus humilis genome assembly reveals gene family evolution and possible genomic basis of calcium accumulation in fruits

Chinese dwarf cherry (Cerasus humilis), which is well known as “calcium fruit” for its high calcium content, is widely utilized in North China for its ecological and economical value. Understanding the evolutionary history and genetic basis underlying the calcium accumulation in this fruit is a fundamental goal in comparative genomics. In this study, we obtained a full phased chromosome-scale C. humilis genome for the cultivar “zhisha” using PacBio circular consensus sequencing reads and Phase genomics Proximo Hi-C technologies. The final assembled genome lengths were 235.41 and 237.35 Mb for primary assembly (p0) and alternate haplotig (p1), respectively, with an N50 contig length of 3.23 Mb. The genome contained 26,800 protein-coding genes, while 41.33% of the genome length consisted of TEs. Phylogenetic analysis revealed that C. humilis displayed a close relationship with Prunus and phylogenetically diverged from its common ancestor ∼23.2 million years ago (MYA). Functional enrichment of expanded gene families in C. humilis genome highlighted genes involved in signal transduction, antiporter activity, polygalacturonase activity, auxin efflux transmembrane transporter activity, and auxin efflux, which is related to calcium transport and distribution. Phylogenetic analysis coupled with tissue-specific expression patterns indicated that PSGs WAK2 and CBL10, may also be responsible for the high Ca2+accumulation ability in C. humilis. These results glean tremendous insight into the fundamental genetic basis of the high calcium content in C. humilis fruit. In addition, the reference C. humilis genome we present in this study will be valuable resources for molecular breeding and genetic research of this fruit species.

Preliminary study to investigate the distribution and effects of certain metals after inhalation of welding fumes in mice.

The most important welding processes used are the gas metal arc (GMA) welding, the tungsten inert gas (TIG) welding, and the manual metal arc (MMA) welding processes. The goal of our investigation was to monitor the distribution of iron (Fe), manganese (Mn), calcium (Ca), and magnesium (Mg) in the lung, spleen, liver, and kidney of mice after inhalation exposure of different welding methods using different steel base materials. The treatment groups were the following: MMA-mild steel, MMA-molybdenum-manganese (MoMn) alloy, TIG-mild steel, and TIG-stainless steel. The samples were taken 24 and 96h after the treatments. Most importantly, it was found that the Mn concentration in the lung' samples of the MMA-mild steel and the MMA-MoMn groups was increased extremely at both sampling times and in the spleen' samples also. In the TIG groups, the rise of the Mn concentration was only considerable in the lungs and spleens at 24h, and emerged concentration was found in the liver in 96h samples. Histopathology demonstrated emerged siderin content in the spleens of the treated animals and in siderin filled macrophages in the lungs mostly in all treated groups. Traces of high-level glycogen retention was found in the MMA groups at both sampling times. Similar glycogen retention in TIG-Ms and TIG stainless group's liver samples and emerged number of vacuoles, especially in the hepatocytes of the TIG-stainless steel 96h group were also found. The mentioned results raise the consequence that there is a considerable difference in the kinetics of the Mn distribution between the MMA- and the TIG-fume-treated groups. Hence, the result suggests that manganese has a particle-size-dependent toxico-kinetics property. The anomaly of the glycogen metabolism indicates the systemic effect of the welding fumes. Also, the numerous vacuoles mentioned above show a possible liver-specific adverse effect of some components of the TIG-stainless steel welding fumes.

Prevalence and distribution of coronary artery calcium in a southeast asian cohort

Abstract Funding Acknowledgements Type of funding sources: None. Background The coronary artery calcium score (CACS) independently predicts the risk of cardiovascular disease and major adverse cardiovascular events. While previous studies have demonstrated regional and ethnic differences in coronary calcification, the distribution of CACS in Southeast Asian (SEA) adults has not been investigated. Purpose The aim of this study was to determine CACS distribution in a SEA cohort living in Singapore. Methods This study involved 4945 asymptomatic patients who underwent CT coronary angiography and calcium scoring as part of screening for cardiovascular disease. Similar to the MESA study, patients with diabetes were analyzed separately due an increased prevalence of coronary calcification. A nonparametric analytical approach was used to determine CACS distribution stratified by age, gender and ethnicity. Results A positive CACS was seen in 43.7% of the overall SEA cohort with a higher prevalence in males (45.2%) than females (36.7%). The onset and burden of coronary calcification was also earlier and more severe in male subjects. There were no significant differences in CACS distribution amongst the three major ethnic groups in our study (p = 0.177). The presence of coronary calcification (CACS &amp;gt;0) was associated with increasing age, male gender and hypertension. Ethnicity, dyslipidemia, smoking and a family history of coronary artery disease did not significantly affect the presence of CACS. Conclusions This study provides a reference CACS distribution in an asymptomatic SEA population. There were no significant differences in CACS distribution amongst the three major ethnic groups living in Singapore.

Effects of Magnesium Application on Tipburn Incidence and Calcium Acquisition in Lisianthus (Eustoma grandiflorum) Cultivars

The occurrence of tipburn is a severe problem in horticulture crop production. A previous study suggested that, in lisianthus, tipburn is caused by imbalanced calcium (Ca) distribution. However, there are few studies on the effects of other cations on tipburn incidence in lisianthus cultivars. In this study, to determine the effect of Magnesium (Mg) concentration in nutrient solution on tipburn incidence and Ca and Mg acquisition, three lisianthus cultivars (‘Celeb Wine’: CW, ‘Reina White’: RW, and ‘Voyage Peach’: VP) were cultivated under different Mg concentrations in nutrient solution (12 ppm, 34.7 ppm, and 75.4 ppm). Under high nutritional Mg concentrations, CW and RW had significantly decreased tipburn severity, while VP showed no significant differences in tipburn severity among the treatments. Total Ca concentrations in all cultivars significantly increased at higher nutritional Mg concentrations, which indicated that Mg application in lisianthus cultivars promoted Ca acquisition. Furthermore, it was suggested that CW and RW had the ability to distribute increased Mg to the tip of the upper leaves, thereby promoting Ca distribution. Thus, a decrease in tipburn severity in CW and RW at higher nutritional Mg concentrations appeared to occur.

Effects of microbial strains on the mechanical and durability properties of lightweight concrete reinforced with polypropylene fiber

This research investigated the impact of calcium carbonate precipitation induced by the activity of four microbial strains known as Sporosarcina pasteurii, Bacillus megaterium, Sporosarcina ureae, and Bacillus licheniformis at cell concentrations of 107 cells/ml on lightweight fiber concrete (LWFC). Three mixed designs with different fiber percentages (0%, 0.5%, and 1%) were considered for evaluation of the effects of these bacteria and polypropylene fiber on the mechanical properties and durability of LWC, which contained Leca aggregate. The experimental results indicated that the simultaneous addition of bacteria and fiber was effective and improved compressive, tensile, and flexural strength. It also reduced concrete water absorption and permeability in the specimens. In specimens with B. licheniformis and 1% fiber, a maximum increase of approximately 32.65% was observed in tensile strength and a 28.39% decrease was observed in water absorption with respect to the control specimens. A comparison of the bacterial specimens revealed that B. licheniformis and B. megateterium performed better in the induction of calcium carbonate precipitation and distribution of fiber in the concrete matrix than S. pasteurii and S. ureae to reduce the balling phenomenon. In addition, SEM-EDX and XRD analyses were conducted to verify the formation of calcium carbonate in the concrete matrix and characterize the crystalline phases of the calcite.

Absorption and Distribution of Calcium (45Ca) Applied to the Surface of Orange (Citrus sinensis) Fruits at Different Developmental Stages

In this study, the rate of absorption and transport of calcium (Ca) in orange fruits (Citrus sinensis cv. Fukumoto) after surface treatment with 45Ca was evaluated by supplying treatments at different dates between fruit set and mid-phase II of growth (i.e., 30, 44, 66 and 99 days after full bloom, DAFB). 45Ca absorption was always detected, but 45Ca application at the fruit set was associated with the highest rates of Ca transport into the pulp (39%) compared to the other treatments (17–19%). Scanning electron microscopy SEM) images of the fruit surface showed the occurrence of stomata along with the entire rind at all the developmental stages evaluated. However, from the beginning of stage I, stomata began to collapse and develop plugs, and this became frequent as the fruit age increased. From 44 DAFB, oil gland density increased, and Ca oxalates (CaOx) were found in the fruit flavedo and albedo. Fruit Ca (not labeled) concentration increased from fruit set (30 DAFB) to 99 DAFB, although oil gland formation and rind growth and differentiation likely hindered Ca transport to internal fruit tissues (pulp). The total Ca concentration in the pedicel was always higher than that in the fruit, with no differences between the first three treatments. The information obtained in this study may be essential for improving Ca fertilizer efficacy in citrus by spray applications.

Imaging of Potassium and Calcium Distribution in Plant Tissues and Cells to Monitor Stress Response and Programmed Cell Death.

In plants, the response to stress, such as salinity, pathogen attack, drought, high concentration of metals, hyperthermia, and hypothermia, is usually accompanied by potassium ion (K+) leakage from the cytosol to the cell wall, mediated by plasma membrane cation conductivity. Stress-induced electrolyte leakage co-occurs with accumulation of reactive oxygen species (ROS) and calcium ions (Ca2+) and often results in programmed cell death (PCD). The development of X-ray and mass spectrometry (MS) based imaging techniques has enabled insight into the spatial tissue and cell-specific redistribution of major and trace elements during the stress response. In this chapter a workflow for sample preparation, imaging, and image analysis by X-ray and MS based techniques is presented.

Significance of Common Blood Test Indexes in the Diagnosis and Prognosis of Multiple Myeloma.

The goal of this study is to explore the clinical value of routine tests in multiple myeloma (MM). A total of 179 MM patients, newly diagnosed in our hospital from January 2010 to December 2018 (case group), as well as 352 cases of healthy individuals (control group) were evaluated. Albumin (Alb), globulin (Glb), albumin/globulin (A/G), creatinine (Cr), calcium (Ca), hemoglobin (Hb), lactate dehydrogenase (LDH), platelet count (Plt), and platelet distribution width (PDW) were compared between the analyzed groups. Respective tests were screened by forward selection. Thereafter, screened out indicators were identified through logistic regression analysis. Risk prediction nomogram, area under curve (AUC), calibration, decision curve analysis (DCA), and clinical impact curve (CIC) were further performed. At the same time, routine test indicators of MM patients for stage and subtype diagnosis, were compared. A correlation analysis between these test indicators and respective disease stages was performed. High stage group and low stage groups were subsequently compared to define the predictive value of single and combined indicators of disease severity. Except for Ca, the difference between the case and control groups for all other blood indicators was statistically significant (p < 0.05). Moreover, the difference in positive rate(s) was statistically significant (p < 0.05). The receiver operating characteristic (ROC) curve of Alb, Hb, and PDW harbored robust discrimination (AUC = 0.960) and appropriate calibration. The DCA and CIC showed that the resulting nomogram had a superior net benefit in predicting MM. Among all indicators, only LDH was statistically reduced in MM patients at ISS stages I, II, and III (p < 0.05). Interestingly, the ISS stage of respective MM patients was positively correlated with Cr (τ = 0.392), while it was negatively correlated with Hb (τ = -0.364). Alb, Glo, A/G, and Hb were significantly distinct between heavy chain (IgG, IgA) and LC, while few significant differences were found between the ISS stages. Lastly, the AUC (0.828) for Cr was greater than that for all other single and combined indicators. The effective application of major indicators measured in routine blood tests can provide important clues for the diagnosis and prognosis of MM.

Pharmacogenomic Screening of Drug Candidates using Patient-Specific hiPSC-Derived Cardiomyocyte High-Throughput Calcium Imaging.

Calcium imaging is an invaluable technique to detect and characterize calcium flux in cells. The use of calcium dye provides information on the concentration and spatial distribution of calcium. Calcium imaging is a well-established technique to assess the calcium-induced calcium release mechanism in cardiomyocytes. It can also be used to characterize mutations in genes crucial for this mechanism that frequently causes arrhythmia. Here we describe a high-throughput methodology of calcium imaging that records individual calcium transients in more than 10,000 humaninduced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in less than 30min.

Scanning transmission X-ray microscopy study of subcellular granules in human platelets at the carbon K- and calcium L2,3-edges

Platelets and their subcellular components (e.g., dense granules) are essential components in hemostasis. Understanding their chemical heterogeneities at the sub-micrometer scale, particularly their activation during hemostasis and production of platelet-derived extracellular vesicles, may provide important insights into their mechanisms; however, this has rarely been investigated, mainly owing to the lack of appropriate chemical characterization tools at nanometer scale. Here, the use of scanning transmission X-ray microscopy (STXM) combined with X-ray absorption near edge structure (XANES) to characterize human platelets and their subcellular components at the carbon K-edge and calcium L2,3-edge, is reported. STXM images can identify not only the spatial distribution of subcellular components in human platelets, such as dense granules (DGs) with sizes of ~200 nm, but also their granule-to-granule chemical heterogeneities on the sub-micrometer scale, based on their XANES spectra. The calcium distribution map as well as the principal component analysis of the STXM image stacks clearly identified the numbers and locations of the calcium-rich DGs within human platelets. Deconvolution of the carbon K-edge XANES spectra, extracted from various locations in the platelets, showed that amide carbonyl and carboxylic acid functional groups were mainly found in the cytoplasm, while ketone-phenol-nitrile-imine, aliphatic, and carbonate functional groups were dominant in the platelet DGs. These observations suggest that platelet DGs are most likely composed of calcium polyphosphate associated with adenosine triphosphate (ATP) and adenosine diphosphate (ADP), with significant granule-to-granule variations in their compositions, while the cytoplasm regions of platelets contain significant amounts of proteins.

The Distribution of Oxygen, Calcium, and Strontium Over the Surface of 21 Com

Abstract Comparison of optical high resolution high signal-to-noise ELODIE spectra of 21 Com taken in 2004 April and separated by about half of the 2 days rotational period, reveals variations of the oxygen, calcium and strontium lines between rotational phases 0.94 and 0.48. Whereas the lines of oxygen and calcium are stronger at phase 0.94, those of strontium strengthen at phase 0.48. The synthesis of strong Sr ii lines yields disk-averaged estimates of the abundances of strontium: about 200 times solar at phase 0.94 and 450 solar at phase 0.48 for strontium. However the O i and Ca ii lines are too blended to derive unambiguous quantitative information on the abundance and distribution of oxygen and calcium over the surface of 21 Com. The likely underabundance of oxygen might be quantified using stronger far-ultraviolet transitions.

Mise au point sur l'athérectomie rotationnelle à haute vitesse par Rotablator en 2021 et données du registre France PCI

Developed in the late 1980s, rotational atherectomy has raised a lot of hope for its innovative principle of selective ablation, allowing volume reduction (instead of redistribution) of atherosclerotic plaque, while sparing healthy tissue. Long shunned for its disappointing results on restenosis, the Rotablator finally reasserted itself in the 2000s; era of drug eluting stents and coronary angioplasty boom, thus generating emergence of complex lesions. Indeed, the Rotablator has demonstrated an undeniable benefit in complex (type C) and calcified lesions preparation (before stenting), with a procedural success rate of 95%. Although these lesions only represent a small amount (2-3%) of percutaneous coronary interventions (PCI), they remain a technical impasse for plain-old balloon angioplasty strategy, making the Rotablator more suitable for these resistant lesions' treatment. Registry data attest the safety of this therapy, with a rate of peri-procedural complications and in-hospital mortality comparable to conventional angioplasty (France PCI register). However, certain specific, rare but serious complications (burr entrapment, broken Rotawire, coronary perforation) justify trained teams, perfect knowledge of the equipment, and strict compliance with good practice guidelines. In 2018, the rise of a new method of atherectomy by intra-vascular lithotripsy (Shockwave) has coincided with Rotablator decreasing activity (this finding being biased by a general decrease in PCI activity due to Covid pandemic). This therapeutic range's enhancement revolutionizes calcified lesions treatment, tending towards precise targeting of each indication, depending in particular on calcium distribution's anatomy in the plaque.