Vapor Nanobubbles around Heated Nanoparticles: Wetting Dependence of the Local Fluid Thermodynamics and Kinetics of Nucleation

Plasmonic nanobubbles are composite objects resulting from the interaction between light and metallic nanoparticles immersed in a fluid. Plasmonic nanobubbles have applications in photothermal therapies, drug delivery, microfluidic manipulations, and solar energy conversion. Their early formation is, however, barely characterized due to the short time and length scales relevant to the process. Here, we investigate, using molecular dynamics (MD) simulations, the effect of nanoparticle wettability on both the local fluid thermodynamics and the kinetics of nanobubble generation in water. We first show that the local onset temperature of vapor nucleation decreases with the nanoparticle/water interfacial energy and may be 100 K below the water spinodal temperature in the case of weak nanoparticle/water interactions. Second, we demonstrate that vapor nucleation may be slower in the case of weak water/nanoparticle interactions. This result, which is qualitatively at odds with the predictions of isothermal classical nucleation theory, may be explained by the competition between two antagonist effects: while, classically, hydrophobicity increases the vapor nucleation rate, it also penalizes interfacial thermal transfer, slowing down kinetics. The kinetics of heat transfer from the nanoparticle to water is controlled by the interfacial thermal conductance. This quantity turns out not only to decrease with the nanoparticle hydrophobicity but also drops down prior to phase change, yielding even longer nucleation times. Such conclusions were reached by considering the comparison between MD and continuous heat transfer models. These results put forward the role of nanoparticle wettability in the generation of plasmonic nanobubbles observed experimentally and open the path to the control of boiling using nanopatterned surfaces.

Dissociation of the Watson-Crick base pairs in vacuum and in aqueous solution: a first-principles molecular dynamics study

The damage of the DNA structure can affect the correct functioning of the cellular processes. This work investigates the required forces to dissociate the Watson-Crick (WC) base pairs AT into A and T, and GC into G and C. The WC base pairs are immersed in water under realistic conditions of temperature, volume, and density that reproduce the main characteristics of a biological system. The simulations are based on first-principles molecular dynamics combined with steering atomic forces. In addition to the force intensities, the charge transfers between the nucleic acid bases, energy variations, and temperature fluctuations in the cleavage moments are reported. With the purpose of evaluating the effects of the aqueous medium, simulations of the WC base pairs in vacuum are included. The results considering the solvated medium are consistent with the experimental measurements, and show the importance of the aqueous solution to regulate the structural modifications of the nucleic acid bases. The investigation contributes with a novel molecular model in molecular simulations, and to better understand the biological processes where the DNA compounds play an active role in life forms.Communicated by Ramaswamy H. Sarma.

Size-dependent effects of the thermal transport at gold nanoparticle-water interfaces

The transfer of heat from a plasmonic nanoparticle to its water environment has numerous applications in the fields of solar energy conversion and photothermal therapies. We use non-equilibrium molecular dynamics to investigate the size-dependent effects of the interfacial thermal conductance of gold nanoparticles immersed in water and of tunable wettability. The interfacial thermal conductance is found to increase when the nanoparticle size decreases. We rationalize such a behavior with a generalized acoustic model, where the interfacial bonding decreases with the nanoparticle size. The analysis of the interfacial thermal spectrum reveals the importance of the low frequency peak of the nanoparticle spectrum as it matches relatively well the oxygen peak in the vibrational spectrum. However, by reducing the nanoparticle size, the low frequency peak is exacerbated, explaining the enhanced heat transfer observed for small nanoparticles. Finally, we assess the accuracy of continuum heat transferequations to describe the thermal relaxation of small nanoparticles with initial high temperatures.We show that, before the nanoparticle looses its integrity, the continuum model succeed in describing with small percentage deviations the molecular-dynamics data. This work brings a simple methodology to understand, beyond the plasmonic nanoparticles, thermal boundary conductance between a nanopartice and its environment.

[Statement of the Spanish Interdisciplinary Vascular Prevention Committee on the updated European Guidelines on Cardiovascular Disease Prevention]

Statement of the Spanish Interdisciplinary Vascular Prevention Committee on the updated European Guidelines on Cardiovascular Disease Prevention. We present the Spanish adaptation of the 2021 European Guidelines on Cardiovascular Disease (CVD) prevention in clinical practice. The current guidelines besides the individual approach greatly emphasize on the importance of population level approaches to the prevention of cardiovascular diseases. Systematic global CVD risk assessment is recommended in individuals with any major vascular risk factor. Regarding LDL-Cholesterol, blood pressure, and glycemic control in patients with diabetes mellitus, goals and targets remain as recommended in previous guidelines. However, it is proposed a new, stepwise approach (Step 1 and 2) to treatment intensification as a tool to help physicians and patients pursue these targets in a way that fits patient profile. After Step 1, considering proceeding to the intensified goals of Step 2 is mandatory, and this intensification will be based on 10-year CVD risk, lifetime CVD risk and treatment benefit, comorbidities and patient preferences. The updated SCORE algorithm-SCORE2, SCORE-OP- is recommended in these guidelines, which estimates an individual's 10-year risk of fatal and non-fatal CVD events (myocardial infarction, stroke) in healthy men and women aged 40-89 years. Another new and important recommendation is the use of different categories of risk according different age groups (< 50, 50-69 ≥ 70 years). Different flow charts of CVD risk and risk factor treatment in apparently healthy persons, in patients with established atherosclerotic CVD, and in diabetic patients are recommended. Patients with chronic kidney disease are considered high risk or very high-risk patients according to the levels of glomerular filtration rate and albumin-to-creatinine ratio. New lifestyle recommendations adapted to the ones published by the Spanish Ministry of Health as well as recommendations focused on the management of lipids, blood pressure, diabetes and chronic renal failure are included.

The damage of the Watson-Crick base pairs by nickel nanoparticles: A first-principles molecular dynamics study

The nickel nanoparticles are harmful atmospheric pollutants, and the damage caused by them in humans has become a topic of great relevance. In this study we investigate the interaction of the Ni2 and Ni3 clusters with the AT and GC Watson-Crick base pairs in an aqueous medium. Molecular dynamics in combination with density functional theory are employed. A novel method is implemented to create realistic thermodynamic conditions (NVT) in the simulations. The energies, the charges of the interacting compounds, the temperature changes, and the geometric rearrangements are reported. The results show the formation of stable organometallic compounds of the nickel nanoparticles with the DNA nucleic acid bases. In this respect, the biological processes where the DNA is implicated may be altered by the formation of such super-structures.

Cost-effectiveness of the Hall Technique in a Randomized Trial

Clinical and patient-reported outcomes were reported for carious primary molars treated with the Hall technique (HT) as compared with conventional carious tissue removal and restorations (i.e., conventional restoration [CR]) in a 5-y randomized controlled practice-based trial in Scotland. We interrogated this data set further to investigate the cost-effectiveness of HT versus CR. A total of 132 children who had 2 matched occlusal/occlusal-proximal carious lesions in primary molars ( n = 264 teeth) were randomly allocated to HT or CR, provided by 17 general dental practitioners. Molars were followed up for a mean 5 y. A societal perspective was taken for the economic analysis. Direct dental treatment costs were estimated from a Scottish NHS perspective (an NHS England perspective was taken for a sensitivity analysis). Initial, maintenance, and retreatment costs, including rerestorations, endodontic treatments, and extractions, were estimated with fee items. Indirect/opportunity costs were estimated with time and travel costs from a UK perspective. The primary outcome was tooth survival. Secondary outcomes included 1) not having pain or needing endodontic treatments/extractions and 2) not needing rerestorations. Cost-effectiveness and acceptability were estimated from bootstrapped samples. Significantly more molars in HT survived (99%, 95% CI: 98% to 100%) than in CR (92%; 87% to 97%). Also, the proportion of molars retained without pain or requiring endodontic treatment/extraction was significantly higher in HT than CR. In the base case analysis (NHS Scotland perspective), cumulative direct dental treatment costs (Great British pound [GBP]) of HT were 24 GBP (95% CI: 23 to 25); costs for CR were 29 (17 to 46). From an NHS England perspective, the cost advantage of HT (29 GBP; 95% CI: 25 to 34) over CR (107; 86 to 127) was more pronounced. Indirect/opportunity costs were significantly lower for HT (8 GBP; 95% CI: 7 to 9) than CR (19; 16 to 23). Total cumulative costs were significantly lower for HT (32 GBP; 95% CI: 31 to 34) than CR (49; 34 to 69). Based on a long-term practice-based trial, HT was more cost-effective than CR with HT retained for longer and experiencing less complications at lower costs.

Comparison and critical appraisal of dengue clinical guidelines and their use in Asia and Latin America

The World Health Organization (WHO) dengue classification scheme for dengue fever (DF) and dengue haemorrhagic fever (DHF)/dengue shock syndrome (DSS) has been adopted as the standard for diagnosis, clinical management and reporting. In recent years, difficulties in applying the WHO case classification have been reported in several countries. A multicenter study was carried out in Asia and Latin America to analyze the variation and utility of dengue clinical guidelines (DCGs) taking as reference the WHO/PAHO guidelines (1994) and the WHO/SEARO guidelines (1998). A document analysis of 13 dengue guidelines was followed by a questionnaire and Focus Group discussions (FGDs) with 858 health care providers in seven countries. Differences in DCGs of the 13 countries were identified including the concept of warning signs, case classification, use of treatment algorithms and grading into levels of severity. The questionnaires and FGDs revealed (1) inaccessibility of DCGs, (2) lack of training, (3) insufficient number of staff to correctly apply the DCGs at the frontline and (4) the unavailability of diagnostic tests. The differences of the DCGs and the inconsistency in their application suggest a need to re-evaluate and standardise DCGs. This applies especially to case classification and case management.

Identification of a novel pseudodeficiency allele in the GLB1 gene in a carrier of GM1 gangliosidosis

The term 'pseudodeficiency' is used in lysosomal storage diseases to denote the situation in which individuals show greatly reduced enzyme activity but remain clinically healthy. Pseudodeficiencies have been reported for several lysosomal hydrolases. GM1 gangliosidosis is a rare autosomal recessive lysosomal storage disorder caused by beta-galactosidase hydrolase deficiency as a result of mutations in the GLB1 gene. Until now, two variants altering the beta-galactosidase activity have been described, p.Arg521Cys and p.Ser532Gly. Here we report the new variant p.Arg595Trp in the GLB1 gene, which markedly reduces beta-galactosidase activity when expressed in COS-1 cells. The variant was identified in the healthy father of a girl with GM1 gangliosidosis. He was a heterozygous compound with p.Arg595Trp in trans with one of the disease-causing mutations identified in his daughter; in leukocytes and plasma he showed lower beta-galactosidase activity than that observed in GM1 gangliosidosis carriers. As this family originated from the Basque Country in the north of Spain, we decided to analyse individuals of Basque and non-Basque origin, finding the p.Arg595Trp allele in 3.2% of Basque and in 0.8% of non-Basque alleles. The detection of the presence of alterations resulting in pseudodeficient activity in leukocytes and plasma is important for the correct diagnosis of GM1 gangliosidosis.

Identification of 14 novel GLB1 mutations, including five deletions, in 19 patients with GM1 gangliosidosis from South America

GM1 gangliosidosis is a lysosomal storage disorder caused by the absence or reduction of lysosomal beta-galactosidase activity because of mutations in the GLB1 gene. Three major clinical forms have been established: type I (infantile), type II (late infantile/juvenile) and type III (adult). A mutational analysis was performed in 19 patients with GM1 gangliosidosis from South America, mainly from Argentina. Two of them were of Gypsy origin. Main clinical findings of the patients are presented. All 38 mutant alleles were identified: of the 22 different mutations found, 14 mutations are described here for the first time. Among the novel mutations, five deletions were found. Four of them are relatively small (c.435_440delTCT, c.845_846delC, c.1131_1145del15 and c.1706_1707delC), while the other one is a deletion of 1529 nucleotides that includes exon 5 and is caused by an unequal crossover between intronic Alu sequences. All the described patients with GM1 gangliosidosis were affected by the infantile form, except for four unrelated patients classified as type II, III, and II/III (two cases). The two type II/III patients bore the previously described p.R201H mutation, while the adult patient bore the new p.L155R. The juvenile patient bore two novel mutations: p.S434L and p.G554E. The two Gypsy patients are homozygous for the p.R59H mutation as are all Gypsy patients previously genotyped.

Selectivity of a model zeolite ring over hydrocarbons with different symmetry, travelling with different orientations and speeds

We explore the selectivity of a model zeolite ring over representative hydrocarbons of crude oil. The model ring consists of 7 silicon tetrahedral units and one chemically active aluminum site through which hydrocarbons with symmetries varying from almost spherically symmetric to linear chains (1D), planar (2D), and pyramidal (3D) structures diffuse. The selectivity is further investigated when the hydrocarbons travel with different orientations and speeds. The semiclassical Born-Oppenheimer molecular dynamics approximation is used to characterize the chemical dynamics, as well as to determine the energetics and reaction products. The simulations reveal noticeable differences in energy profiles and charge populations. Our results are important to understand aspects of mass transport and some of the factors that control the catalytic activity in zeolites.

Functional and molecular modelling studies of two hereditary fructose intolerance-causing mutations at arginine 303 in human liver aldolase

We have identified a novel hereditary fructose intolerance mutation in the aldolase B gene (i.e. liver aldolase) that causes an arginine-to-glutamine substitution at residue 303 (Arg(303)-->Gln). We previously described another mutation (Arg(303)-->Trp) at the same residue. We have expressed the wild-type protein and the two mutated proteins and characterized their kinetic properties. The catalytic efficiency of protein Gln(303) is approx. 1/100 that of the wild-type for substrates fructose 1,6-bisphosphate and fructose 1-phosphate. The Trp(303) enzyme has a catalytic efficiency approx. 1/4800 that of the wild-type for fructose 1,6-bisphosphate; no activity was detected with fructose 1-phosphate. The mutation Arg(303)-->Trp thus substitution impairs enzyme activity more than Arg(303)-->Gln. Three-dimensional models of wild-type, Trp(303) and Gln(303) aldolase B generated by homology-modelling techniques suggest that, because of its larger size, tryptophan exerts a greater deranging effect than glutamine on the enzyme's three-dimensional structure. Our results show that the Arg(303)-->Gln substitution is a novel mutation causing hereditary fructose intolerance and provide a functional demonstration that Arg(303), a conserved residue in all vertebrate aldolases, has a dominant role in substrate binding during enzyme catalysis.

Microstructure and properties of pitch-based carbon composites

Pitches prepared in the laboratory by thermal treatment and air-blowing of a commercial coal-tar pitch were used as matrix precursors of carbon composites using granular petroleum coke, foundry coke, amorphous graphite and anthracite. Pitches were characterized by standard procedures (elemental analysis, softening point, solubility tests and carbon yield) and light microscopy (mesophase content). Pitch pyrolysis behaviour was monitored by thermogravimetric analysis and from the optical texture of cokes. Pitch wettability to the different carbons, at different temperatures, was also studied. Experimental conditions selected for the preparation of composites were based on pitch composition and properties. The main microstructural features of composites were determined by light microscopy and scanning electron microscopy. Composite properties were described in terms of their density, porosity and compressive strength, and related to composite microstructure and the characteristics of the precursors. Thermal treatment and air-blowing of pitch improved carbon composite structure and properties. The lowest porosities and best mechanical properties were observed in those composites obtained with the thermally treated pitches combined with foundry coke and anthracite.

Novel six-nucleotide deletion in the hepatic fructose-1,6-bisphosphate aldolase gene in a patient with hereditary fructose intolerance and enzyme structure-function implications

Hereditary fructose intolerance (HFI) is an autosomal recessive human disease that results from the deficiency of the hepatic aldolase isoenzyme. Affected individuals will succumb to the disease unless it is readily diagnosed and fructose eliminated from the diet. Simple and non-invasive diagnosis is now possible by direct DNA analysis that scans for known and unknown mutations. Using a combination of several PCR-based methods (restriction enzyme digestion, allele specific oligonucleotide hybridisation, single strand conformation analysis and direct sequencing) we identified a novel six-nucleotide deletion in exon 6 of the aldolase B gene (delta 6ex6) that leads to the elimination of two amino acid residues (Leu182 and Val183) leaving the message inframe. The three-dimensional structural alterations induced in the enzyme by delta 6ex6 have been elucidated by molecular graphics analysis using the crystal structure of the rabbit muscle aldolase as reference model. These studies showed that the elimination of Leu182 and Val183 perturbs the correct orientation of adjacent catalytic residues such as Lys146 and Glu187.

Molecular basis of hereditary fructose intolerance in Italy: identification of two novel mutations in the aldolase B gene

We screened the aldolase B gene in 14 unrelated Italian patients with hereditary fructose intolerance (HFI), and found two novel disease related mutations: a single nucleotide deletion in exon 2 (delta A20) that leads to an early stop codon, and a C-->T transition in exon 8 that substitutes an Arg with a Trp residue at codon 303 (R303W).

The molecular basis of hereditary fructose intolerance in Italian children

We investigated the molecular defects of the aldolase B gene in five unrelated patients affected by hereditary fructose intolerance. The techniques used were DNA amplification, direct sequencing and allele-specific oligonucleotide (ASO) hybridization. The most frequent substitutions found in the hereditary fructose intolerance alleles analysed were the A174D and the A149P mutations, which account for 50% and 30% of the alleles, respectively. In two unrelated families, we found a rare mutation, the MD delta 4 previously described only in one British family, which may be an important cause of the disease in Italy.

Extracellular complementation of a developmental mutation implicates a small sporulation protein in aerial mycelium formation by S. coelicolor

The filamentous bacterium S. coelicolor differentiates by forming aerial hyphae, which protrude into the air and metamorphose into chains of spores. Aerial hyphae formation is associated with the production of a small, abundant protein, SapB, which is present in a zone around colonies of differentiating bacteria. Production of SapB is impaired in bld mutants, which are blocked in aerial hyphae formation, but not in whi mutants in which spore formation is prevented. We report that aerial hyphae formation by a newly identified bld mutant is restored by juxtaposition of the mutant near colonies of SapB-producing bacteria or by the application of the purified protein near mutant colonies. These observations implicate SapB in aerial mycelium formation and suggest that SapB is a morphogenetic protein that enables hyphae on the surface of colonies to grow into the air.

Assignment of human aldolase C gene to chromosome 17, region cen----q21.1

The mapping of the gene coding for human aldolase C has been studied using a specific cDNA probe and genomic blots from a panel of human-hamster somatic cell hybrids. The results show that the aldolase C gene is on chromosome 17. In situ experiments have restricted the mapping to the region 17cen----q21.1. Using the same panel of human-hamster somatic cell hybrids, we have confirmed the localization of aldolase A and B on chromosomes 16 and 9, respectively.

Visualizing gene expression in time and space in the filamentous bacterium Streptomyces coelicolor

Streptomycetes are prokaryotic microorganisms that exhibit a complex, mycelial fungus-like cycle of morphological differentiation. Development involves at least two spatially separated types of cells: the branching hyphae of the substrate mycelium, which penetrate the stratum upon which the colony feeds, and the upwardly protruding hyphae of the aerial mycelium, which undergo metamorphosis into spores. The luciferase-encoding luxA and luxB operon of the luminescent marine bacterium Vibrio harveyi was used as a promoter probe to visualize gene expression in differentiating colonies of Streptomyces coelicolor. Promoters for developmental genes of several kinds gave distinctive temporal and spatial patterns of light emission.

Promoter determining the timing and spatial localization of transcription of a cloned Streptomyces coelicolor gene encoding a spore-associated polypeptide

Streptomyces coelicolor is a filamentous, gram-positive bacterium that exhibits a complex cycle of morphological differentiation involving the formation of an aerial mycelium of multinucleoid hyphae which undergo septation to form long chains of spores. We report the identification of two proteins of 13 and 3 kilodaltons, designated SapA and SapB, respectively, that are produced during formation of the aerial mycelium and are found in assocation with purified, mature spores. We cloned the structural gene (sapA) for one of these spore-associated proteins. Nucleotide sequence analysis suggests that the 13-kilodalton polypeptide is derived from a larger pre- or preproprotein containing a leader sequence of 37 amino acids. Nuclease protection-hybridization analysis and experiments using the Vibrio harveyi, luciferase-encoding luxAB operon as a gene tag demonstrated that expression of sapA is controlled from a promoter contained within a region of less than 110 base pairs in length, whose transcription start site is located approximately 50 base pairs upstream from the initiation codon for the sapA open reading frame. Transcription of sapA was induced at the time of appearance of the aerial mycelium, and the level of sapA transcripts was significantly reduced in certain mutants blocked in aerial mycelium (bld) and or spore (whi) formation. As further evidence of the association of sapA transcription with morphological differentiation, experiments in which we monitored sapA transcription topographically by use of a sapA-luxAB operon fusion demonstrated a close spatial correlation between colony regions undergoing aerial mycelium formation and zones of sapA-promoted light emission.

Mapping of a restriction fragment length polymorphism within the human aldolase B gene

Peripheral blood DNA was hybridized to the full-length cDNA and the cloned structural gene of human aldolase B. With PvuII endonuclease a restriction fragment length polymorphism was detected that was present in the heterozygous state in about 21% of the individuals tested. A map of the human aldolase gene was constructed for the two groups of individuals found to produce different fragments after PvuII digestion. This allowed the localization of the polymorphic site within the gene, which was found to be due to the loss of a PvuII site in the last intron upstream from the 3' end. This polymorphism may be used as a genetic marker to study individuals affected by hereditary fructose intolerance.

Mapping through somatic cell hybrids and cDNA probes of protein C to chromosome 2, factor X to chromosome 13, and alpha 1-acid glycoprotein to chromosome 9

The previously unassigned gene coding for the anti-coagulatory protein C has been mapped on chromosome 2 using a cDNA probe and genomic blots from a human-hamster somatic cell hybrid panel. The assignments of the genes coding for the coagulation factor X to chromosome 13, and for alpha 1-acid glycoprotein to chromosome 9 have been confirmed using a similar direct approach.

Human aldolase B cDNA detects a Pvu II RFLP in healthy individuals

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Calcium blocking properties of piprofurol

Piprofurol is a benzofuran chalcon derivative. It was studied under various experimental conditions which allow the recognition of calcium antagonistic activity. Piprofurol inhibited in a concentration-dependent manner the calcium-induced contractions in isolated potassium depolarized preparations of rat aorta (pA2: 9.29) and relaxed the K+-induced contraction of the dog coronary artery and the rabbit basilar artery (IC's 50: 2 10(-8) M; 3 10(-9) M). Piprofurol also inhibited noradrenaline-induced vascular smooth muscle contractions but the antagonism was clearly noncompetitive and the contractions induced were altered by concentrations two orders of magnitude higher than the concentration inhibiting calcium-induced contractions. Calcium antagonism was demonstrated in cardiac muscle: calcium mediated slowly rising action potentials were evoked in partially depolarized guinea-pig papillary muscle by electrical stimulation in the presence of isoprenaline. Piprofurol decreased the rate of rise of these slow action potentials. The inhibitory effect was reversed by an elevation of the calcium concentration in the bath fluid. Piprofurol exerts a negative inotropic effect (IC50: 5 10(-6) M) on guinea-pig papillary muscle. The ratio IC50 inotropic action/IC50 relaxant activity was 230, i.e. higher than that obtained with verapamil or diltiazem, and near that observed for cinnarizine. The pharmacological profile from in vivo dog experiments is in agreement with its in vitro properties: coronary sinus blood flow was increased and heart rate decreased. These effects suggested a potentially anti-ischaemic activity. This is confirmed in anaesthetized dogs, where piprofurol reduced the epicardial ST-segment elevation following coronary artery occlusion, and in isolated heart preparations, where it decreased the leakage of LDH during periods of anoxia and reoxygenation.

Isolation and nucleotide sequence of a full-length cDNA coding for aldolase B from human liver

Two recombinant clones, pA2 and pA3, containing cDNA sequences for human aldolase B have been isolated from a full length human liver cDNA library. The larger one, pA3, has been subcloned in M13 phage and completely sequenced with the chain terminator method. The sequence covers 1,600 nucleotides including the whole coding region (1,050 nucleotides), 67 nucleotides from the 5' non-coding region and the whole 3' non-coding region, 440 nucleotides long, down to the poly-A tail. Comparison with rabbit aldolase A and with a partial sequence of rat aldolase B, shows a homology of about 76% for aldolase A and of about 94% for aldolase B, which indicates that the sequenced cDNA codes for the liver isoenzyme. This is the first complete sequence reported for human aldolase B. The pA3 clone strongly hybridizes to 18S mRNA from human adult liver as expected from the size of the isolated cDNA.