Tricalcium phosphate-loaded injectable hydrogel as a promising osteogenic and bactericidal teicoplanin-delivery system for osteomyelitis treatment: An in vitro and in vivo investigation.

Osteomyelitis is an inflammation of bone tissue usually caused by pyogenic bacteria. The most recurrent clinical approach consists of bone debridement followed by parenteral administration of antibiotics. However, systemic antibiotic treatment has limitations regarding absorption rate and bioavailability over time. The main challenge of osteomyelitis treatment consists of coupling the persistent infection treatment with the regeneration of the bone debrided. In this work, we developed an injectable drug delivery system based on poloxamer 407 hydrogel containing undoped Mg, Zn-doped tricalcium phosphate (ß-TCP), and teicoplanin, a broad-spectrum antibiotic. We evaluated how the addition of teicoplanin and ß-TCP affected the micellization, gelation, particle size, and surface charge of the hydrogel. Later, we studied the hydrogel degradation and drug delivery kinetics. Finally, the bactericidal, biocompatibility, and osteogenic properties were evaluated through in vitro studies and confirmed by in vivo Wistar rat models. Teicoplanin was found to be encapsulated in the corona portions of the hydrogel micelles, yielding a bigger hydrodynamics radius. The encapsulated teicoplanin showed a sustained release over the evaluated period, enough to trigger antibacterial properties against Gram-positive bacteria. Besides, the formulations were biocompatible and showed bone healing ability and osteogenic properties. Finally, in vivo studies confirmed that the proposed locally injected formulations yielded osteomyelitis treatment with superior outcomes than parenteral administration while promoting bone regeneration. In conclusion, the presented formulations are promising drug delivery systems for osteomyelitis treatment and deserve further technological improvements.

Employment of pqqE gene as molecular marker for the traceability of Gram negative phosphate solubilizing bacteria associated to plants.

Insoluble phosphorous compounds solubilization by soil bacteria is of great relevance since it puts available the phosphorus to be used by plants. The production of organic acids is the main microbiological mechanism by which insoluble inorganic phosphorus compounds are solubilized. In Gram negative bacteria, gluconic acid is synthesized by the activity of the holoenzyme glucose dehydrogenase-pyrroloquinoline quinine named GDH-PQQ. The use of marker genes is a very useful tool to evaluate the persistence of the introduced bacteria and allow to follow-up the effect of biotic and abiotic factors on these beneficial microorganisms in the soil. In previous studies we detected the presence of the pqqE gene in a great percentage of both non-culturable and culturable native soil bacteria. The objective of this study was to analyze the phylogeny of the sequence of pqqE gene and its potential for the study of phosphate solubilizing bacteria from pure and mixed bacterial cultures and rhizospheric soil samples. For this, the presence of the pqqE gene in the genome of phosphate solubilizing bacteria that belong to several bacteria was determined by PCR. Also, this gene was analyzed from mixed bacterial cultures and rhizospheric soil associated to peanut plants inoculated or not with phosphate solubilizing bacteria. For this, degenerate primers designed from several bacterial genera and specific primers for the genus Pseudomonas spp., designed in this study, were used. DNA template used from simple or mixed bacterial cultures and from rhizospheric soil samples was obtained using two different DNA extraction techniques. Results indicated that pqqE gene amplification product was found in the genome of all Gram negative phosphate solubilizing bacteria analyzed. It was possible to detect this gene in the DNA obtained from mixed cultures where these bacteria grew in interaction with other microorganisms and in that obtained from rhizospheric soil samples inoculated or not with these bacteria. The phylogenetic analysis indicated that pqqE gene is a conserved gene within related genera. In conclusion, pqqE gene could be a potential marker for the study of phosphate solubilizing bacterial populations.

Phenotypic and genomic characterization of phosphate-solubilizing rhizobia isolated from native Mimosa and Desmodium in Brazil.

The phosphate (P)-solubilizing potential of rhizobia isolated from active root nodules of Brazilian native Mimosa and Desmodium was assessed. Out of the 15 strains selected, five Paraburkholderia isolated from Mimosa spp. grown in rocky outcrops stood out. The Ca3(PO4)2-solubilizing efficiency of these strains ranged from 110.67 to 356.3 mgL-1, with less expressive results for FePO4 and Al(H2PO4)3, that might be attributed to the low solubility of these two P compounds. Paraburkholderia strains CNPSo 3281 and CNPSo 3076 were the most efficient siderophore producers (44.17 and 41.87 µMol EDTA) and two of the top FePO4 solubilizers. Acidification of the culture media was observed for all the strains and P sources. Regarding Ca3(PO4)2 solubilization, the main organic acids detected were glucuronic (an important component of rhizobia exopolysaccharides) and gluconic acids. Genomic analysis of P. nodosa CNPSo 3281 and CNPSo 3076 along with other phosphate-solubilizing Paraburkholderia species of the genus pointed out a conserved gene organization of phoUBR, pstSCAB, ppk and ppx. Greenhouse experiment revealed that P. nodosa CNPSo 3281 and CNPSo 3076 promoted maize growth under low P. Our results indicate the relevance of native rhizobia as multifunctional plant-associated bacteria and the rocky outcrops ecosystems as hotspots for bioprospection.

Comparison of the physical properties of glass ionomer modified with silver phosphate/hydroxyapatite or titanium dioxide nanoparticles: in vitro study.

Glass ionomer cements (GICs) are the common materials employed in pediatric dentistry because of their specific applications in class I restorations and atraumatic restoration treatments (ART) of deciduous teeth in populations at high risk of caries. Studies show a limited clinical durability of these materials. Attempts have thus been made to incorporate nanoparticles (NPs) into the glass ionomer for improving resistance and make it like the tooth structure. An in vitro experimental study was conducted using the required samples dimensions and prepared based on the test being carried out on the three groups with or without the modification of light-cured glass ionomer. Samples were grouped as follows: control group (G1_C), 2% silver phosphate/hydroxyapatite NPs group (G2_SPH), and 2% titanium dioxide NPs group (G3_TiO2). The physical tests regarding flexural strength (n = 10 per group), solubility (n = 10 per group), and radiopacity (n = 3 per group) were performed. The data were analyzed by Shapiro Wilks test, and one-way analysis of variance (one-way ANOVA), and multiple comparisons by post hoc Tukey's test. The p-value of < 0.05 was considered significant. No statistically significant difference was observed between the control group (G1_C) and (G2_SPH) (p = 0.704) in the flexural strength test, however differences were found between G2_SPH and G3_TiO2 groups, ANOVA (p = 0.006); post hoc Tukey's test (p = 0.014). Pertaining to the solubility, G2_SPH obtained the lowest among the three groups, ANOVA (p = 0.010); post hoc Tukey's test (p = 0.009). The three study groups obtained an adequate radiopacity of >1 mm Al, respectively. The resin-modified glass ionomer cement (RMGIC) was further modified with 2% silver phosphate/hydroxyapatite NPs to improve the physical properties such as enhancing the solubility and sorption without compromising the flexural strength and radiopacity behavior of modified RMGIC. The incorporation of 2% titanium dioxide NPs did not improve the properties studied.

Enhancing Phosphate Uptake and Antifungal Activity in Tomato Plants via Bacillus licheniformis Mutagenesis: Evaluating Growth Parameters.

The objective of the investigation was to improve phosphate solubilization in tomato plants by Bacillus licheniformis, a rhizobacterium that promotes plant growth. Ultraviolet (UV) radiation, Ethyl methanesulfonate (EMS) and Ethidium bromide (EtBr) mutagenesis produced twenty-one mutants. Phosphate solubilization was higher in the PM7 (physical mutant) (121.00 g mL-1) than in the wild type (82.00 g mL-1). PM7 showed high antifungal activity against Phytophthora capsici, Fusarium oxysporum and Dematophora necatrix besides increased siderophore production and HCN production. In a net-house experiment, PM7 improved root and shoot parameters, P assimilation and soil P availability in tomato plants. This study demonstrates the potential of PM7 as an effective rhizobacterium for enhancing nutrient availability and plant growth.

Galactose-1-phosphate inhibits cytochrome c oxidase and causes mitochondrial dysfunction in classic galactosemia.

Classic galactosemia is an inborn error of metabolism caused by mutations in the GALT gene resulting in the diminished activity of the galactose-1-phosphate uridyltransferase enzyme. This reduced GALT activity leads to the buildup of the toxic intermediate galactose-1-phosphate and a decrease in ATP levels upon exposure to galactose. In this work, we focused our attention on mitochondrial oxidative phosphorylation in the context of this metabolic disorder. We observed that galactose-1-phosphate accumulation reduced respiratory rates in vivo and changed mitochondrial function and morphology in yeast models of galactosemia. These alterations are harmful to yeast cells since the mitochondrial retrograde response is activated as part of the cellular adaptation to galactose toxicity. In addition, we found that galactose-1-phosphate directly impairs cytochrome c oxidase activity of mitochondrial preparations derived from yeast, rat liver, and human cell lines. These results highlight the evolutionary conservation of this biochemical effect. Finally, we discovered that two compounds - oleic acid and dihydrolipoic acid - that can improve the growth of cell models of mitochondrial diseases, were also able to improve galactose tolerance in this model of galactosemia. These results reveal a new molecular mechanism relevant to the pathophysiology of classic galactosemia - galactose-1-phosphate-dependent mitochondrial dysfunction - and suggest that therapies designed to treat mitochondrial diseases may be repurposed to treat galactosemia.

Inoculation with Bacillus megaterium CNPMS B119 and Bacillus subtilis CNPMS B2084 improve P-acquisition and maize yield in Brazil.

Phosphorus (P) is a critical nutrient for plant growth, yet its uptake is often hindered by soil factors like clay minerals and metal oxides such as aluminum (Al), iron (Fe), and calcium (Ca), which bind P and limit its availability. Phosphate-solubilizing bacteria (PSB) have the unique ability to convert insoluble P into a soluble form, thereby fostering plant growth. This study aimed to assess the efficacy of inoculation of Bacillus megaterium B119 (rhizospheric) and B. subtilis B2084 (endophytic) via seed treatment in enhancing maize yield, grain P content, and enzyme activities across two distinct soil types in field conditions. Additionally, we investigated various mechanisms contributing to plant growth promotion, compatibility with commercial inoculants, and the maize root adhesion profile of these strains. During five crop seasons in two experimental areas in Brazil, Sete Lagoas-MG and Santo Antônio de Goiás-GO, single inoculations with either B119 or B2084 were implemented in three seasons, while a co-inoculation with both strains was applied in two seasons. All treatments received P fertilizer according to plot recommendations, except for control. Both the Bacillus strains exhibited plant growth-promoting properties relevant to P dynamics, including phosphate solubilization and mineralization, production of indole-3-acetic acid (IAA)-like molecules, siderophores, exopolysaccharides (EPS), biofilms, and phosphatases, with no antagonism observed with Azospirillum and Bradyrizhobium. Strain B2084 displayed superior maize root adhesion compared to B119. In field trials, single inoculations with either B119 or B2084 resulted in increased maize grain yield, with relative average productivities of 22 and 16% in Sete Lagoas and 6 and 3% in Santo Antônio de Goiás, respectively. Co-inoculation proved more effective, with an average yield increase of 24% in Sete Lagoas and 11% in Santo Antônio de Goiás compared to the non-inoculated control. Across all seasons, accumulated grain P content correlated with yield, and soil P availability in the rhizosphere increased after co-inoculation in Santo Antônio de Goiás. These findings complement previous research efforts and have led to the validation and registration of the first Brazilian inoculant formulated with Bacillus strains for maize, effectively enhancing and P grain content.

Effect of the calcium silicate and sodium phosphate remineralizing products on bleached enamel.

Context and Aims: This study evaluated the effect of calcium silicate and sodium phosphate (CSSP) dentifrice and serum on the surface of enamel bleached with hydrogen peroxide (H2O2). Materials and Methods: A total of 160 bovine enamel slabs were bleached with 35% H2O2 and treated with sodium fluoride (NaF) dentifrice-GI, CSSP dentifrice-GII; CSSP dentifrice + CSSP serum-GIII, or NaF dentifrice + NaF gel-GIV. The dentifrices were applied using a brushing machine three times daily for 7 days. After brushing, sodium phosphate gel and CSSP serum were applied. The microhardness (KNH, n = 14), surface roughness (Ra, n = 14), energy dispersive spectroscopy (n = 6), and scanning electron microscopy (n = 6) were assessed at t0 (before bleaching), t1 (after bleaching), and t2 (after postbleaching treatments). Statistical Analysis Used: The data were subjected to a two-way analysis of variance and Bonferroni's test. Results: The KNH decreased at t1 (P < 0.001) but recovered at t2 for all treatments, although only GII showed restored baseline values (P = 0.0109). The surface roughness increased at t1 (P < 0.001) and reduced at t2 (P < 0.001) for all groups, with no significant differences among groups. Enamel composition and morphology did not differ after the treatments, except for silicon accumulation in GIII. Conclusions: Postbleaching treatment with CSSP dentifrice and serum yielded superior remineralizing effects on bleached enamel.

Competitive oxidation of key pentose phosphate pathway enzymes modulates the fate of intermediates and NAPDH production.

The oxidative phase of the pentose phosphate pathway (PPP) involving the enzymes glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconolactonase (6PGL), and 6-phosphogluconate dehydrogenase (6PGDH), is critical to NADPH generation within cells, with these enzymes catalyzing the conversion of glucose-6-phosphate (G6P) into ribulose-5-phosphate (Ribu5-P). We have previously studied peroxyl radical (ROO•) mediated oxidative inactivation of E. coli G6PDH, 6PGL, and 6PGDH. However, these data were obtained from experiments where each enzyme was independently exposed to ROO•, a condition not reflecting biological reality. In this work we investigated how NADPH production is modulated when these enzymes are jointly exposed to ROO•. Enzyme mixtures (1:1:1 ratio) were exposed to ROO• produced from thermolysis of 100 mM 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). NADPH was quantified at 340 nm, and protein oxidation analyzed by liquid chromatography with mass spectrometric detection (LC-MS). The data obtained were rationalized using a mathematical model. The mixture of non-oxidized enzymes, G6P and NADP+ generated ∼175 µM NADPH. Computational simulations showed a constant decrease of G6P associated with NADPH formation, consistent with experimental data. When the enzyme mixture was exposed to AAPH (3 h, 37 °C), lower levels of NADPH were detected (∼100 µM) which also fitted with computational simulations. LC-MS analyses indicated modifications at Tyr, Trp, and Met residues but at lower concentrations than detected for the isolated enzymes. Quantification of NADPH generation showed that the pathway activity was not altered during the initial stages of the oxidations, consistent with a buffering role of G6PDH towards inactivation of the oxidative phase of the pathway.

Rhizospheric Bacteria of Cover Legumes from Acidic Soils Are Capable of Solubilizing Different Inorganic Phosphates.

Due to its adsorption with aluminum and iron hydroxides, phosphorus viability is low in acidic soils; thus, the aim of this study was to isolate and identify bacteria from the rhizosphere of four legumes growing in acidic soils of the Cumbaza Sub-basin, San Martín, Peru, as well as to characterize their ability to solubilize aluminum phosphate and iron phosphate. The isolation process was conducted on TSA medium and the isolates were classified based on their origin and morphocolonial characteristics, with the bacillary shape being the most frequent, followed by cocci. To assess the solubilization of aluminum and iron phosphates, the liquid medium GELP was employed. Sixteen strains were selected, among which three stood out for their effectiveness in solubilizing AlPO4 (Sfcv-098-02, 22.65 mg L-1; Sfc-093-04, 26.50 mg L-1; and Sfcv-041-01-2, 55.98 mg L-1) and one for its ability to solubilize FePO4 (Sfcr-043-02, 32.61 mg L-1). These four strains were molecularly characterized, being identified as Enterobacter sp., Pseudomonas sp., and Staphylococcus sp. Additionally, a decrease in pH was observed in the reactions, with values ranging from 5.23 to 3.29, which enhanced the phosphate of solubilization. This suggests that the selected bacteria could be used to improve phosphorus availability in agricultural soils.

Phosphate uptake in PhoX: Molecular mechanisms.

PhoX is a high-affinity phosphate binding protein, present in Xanthomonas citri, a phytopathogen responsible for the citrus canker disease. Performing molecular dynamics simulations and different types of computational analyses, we study the molecular mechanisms at play in relation to phosphate binding, revealing the global functioning of the protein: PhoX naturally oscillates along its global normal modes, which allow it to explore both bound and unbound conformations, eventually attracting a nearby negative phosphate ion to the highly positive electrostatic potential on its surface, particularly close to the binding pocket. There, several hydrogen bonds are formed with the two main domains of the structure. Phosphate creates, in this way, a strong bridge that connects the domains, keeping itself between them, in a tight closed conformation, explaining its high binding affinity.

Ion release mechanisms in composites containing CaP particles and hydrophilic monomers.

OBJECTIVE: To investigate the effect of hydrophilic/permeable polymer matrices on water sorption/solubility (WS/SL), Ca2+ release, mechanical properties and hydrolytic degradation of composites containing dicalcium phosphate dihydrate (DCPD) particles. METHODS: Six composites were tested, all with 10 vol% of glass particles and either 30 vol% or 40 vol% DCPD. Composites containing 1BisGMA:1TEGDMA in mols (at both inorganic levels) were considered controls. Four materials were formulated where 0.25 or 0.5 of the BisGMA/TEGDMA was replaced by pyromellitic dianhydride glycerol dimethacrylate (PMGDM)/ polyethylene glycol dimethacrylate (PEGDMA). Composites were tested for degree of conversion (FTIR spectroscopy), WS/SL (ISO 4049) and Ca2+ release (inductively coupled plasma optical emission spectroscopy). Fracture toughness (FT) and biaxial flexural strength/modulus (BFS/FM) were determined after 24 h and 60 days in water. The contributions of diffusional and relaxational mechanisms to Ca2+ release kinetics were analyzed using the semi-empirical Salim-Peppas model. Data were analysed by ANOVA/Tukey test (alpha: 0.05). RESULTS: WS/SL was higher for composites containing PMGDM/PEGDMA compared to the controls (p < 0.001). Only at 40% DCPD the 0.5 PMGDM/PEGDMA composite showed statistically higher Ca2+ release than the control. Relaxation diffusion was the main release mechanism. Initial FT was not negatively affected by matrix composition. BFS (both DCPD fractions) and FM (30% DCPD) were lower for composites with hydrophilic/permeable networks (p < 0.01). After 60 days in water, composites with PMGDM/PEGDMA presented significant reductions in FT, while all composites had reductions in BFS/FM. SIGNIFICANCE: Increasing matrix hydrophilicity/permeability significantly increased Ca2+ release only at a high DCPD fraction.

The effect of nutritional and oxidative stress on the metabolome of Trypanosoma cruzi.

Trypanosoma cruzi, a flagellated protozoan, is the causative agent of Chagas disease. The parasite has developed various mechanisms to get through its intricate life cycle and adapt to different evolutionary phases. T. cruzi proliferates in the insect vector's digestive tract as an epimastigote form, encountering fluctuating nutrient availability and oxidative stress caused by the digestion of red blood cells from the mammalian host blood meal. To unravel how the parasite's metabolism adapts to these changing conditions, we conducted an analysis of the chemical species present in epimastigote forms. This involved comparing cultured parasites with those subjected to nutritional deficiency or oxidative stress using untargeted metabolomics. We looked at 21 samples: seven biological copies of parasites that were actively growing, seven samples that were put in a medium without nutrients for 3 h, and seven samples that were treated with glucose oxidase for 30 min to make H2O2 continuously. Importantly, in all conditions, parasite viability was maintained when the samples were collected. Upon nutrient removal, we observed a substantial decrease in amino acids and carbohydrate metabolites, accompanied by the accumulation of fatty acids and steroids, with the predominance of inositol and sphingolipid metabolism, along with a simultaneous decrease in the levels of H2O2. In the presence of H2O2, a significant rise in components of the pentose pathway and specific amino acids such as methionine and serine occurred, along with pathways related to an increase in antioxidant species metabolism such as ribulose 5-phosphate and glyceric acid. Conversely, fatty acid and steroid levels decrease. We found no common increase in metabolites or lipids. In contrast, eight species (succinic acid, glutamic acid, valine, 2-hydroxyisocaproic acid, alanine, indolelactic acid, proline, and lanosterol) were consumed under both stresses. These findings underscore the rapid and distinct enrichment responses in amino acids, lipids, and carbohydrates required to cope with each different environmental condition. We concluded that T. cruzi presents a flexible metabolism that rapidly adapts to variable changes in the environment.

Biomineralization and remineralizing potential of toothpastes containing nanosized ß-calcium glycerophosphate: an in vitro study.

To evaluate the effect of 1100 ppm F toothpastes supplemented with micrometric or nanosized ß-CaGP (ß-CaGPm/ß-CaGPn) on artificial enamel remineralization, using a pH cycling model. Enamel blocks with artificial caries were randomly allocated into ten groups (n = 10), according to the toothpastes: without fluoride/ß-CaGPm/ß-CaGPn (negative control); 1100 ppm F (1100F); 1100F plus 0.125%, 0.25%, 0.5%, and 1.0% of ß-CaGPm or ß-CaGPn. The blocks were treated 2×/day with slurries of toothpastes. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); integrated mineral loss (ΔIMR); fluoride (F), calcium (Ca), and phosphorus (P) concentrations in the enamel; polydispersity index (PdI); and zeta potential (Zp) were determined. The data were analyzed by ANOVA (p < 0.001). For Zp/PdI, no significance was observed when comparing the means (p > 0.001). The treatment with 1100F-0.25%ß-CaGPn led to %SHR ∼57 higher when compared to the 1100F group (p < 0.001). The lowest ΔKHN was observed for the 1100F-0.25%ß-CaGPn group (p < 0.001). The ΔIMR was lower (∼201%) for the 1100F-0.25%ß-CaGPn when compared to 1100F (p < 0.001). The association of ß-CaGPm and ß-CaGPn to 1100F did not influence its F concentration (p > 0.001). The highest increase in Ca and P was observed for 1100F-0.25%ß-CaGPn (p < 0.001). The addition of 0.25%ß-CaGPn to 1100F toothpaste was able to promote an additional remineralizing effect of artificial caries lesions.

Structural and functional characterization of mycobacterial PhoH2 and identification of potential inhibitor of its enzymatic activity.

Mycobacterium tuberculosis is composed of a cumbersome signaling and protein network which partakes in bacterial survival and augments its pathogenesis. Mycobacterial PhoH2 (Mt-PhoH2) is a signaling element and a predictive phosphate starvation protein that works in an ATP-dependent manner. Here, we elaborated the characterization of Mt-PhoH2 through biophysical, biochemical, and computational methods. In addition to its intrinsic ATPase activity, the biochemical experiments revealed its GTPase activity and both activities are metal ion dependent. Magnesium, manganese, copper, iron, nickel, zinc, cesium, calcium, and lithium were examined for their effect on activity, and the optimum activity was found with 10 mM of Mg2+ ions. The kinetic parameters of 3 µM Mt-PhoH2 were observed as Km 4.873 ± 0.44 µM, Vmax 12.3817 ± 0.084 µM/min/mg, Kcat 0.0075 ± 0.00005 s-1, and Kcat/Km 0.0015 ± 0.000001 µM-1 s-1 with GTP. In the case of GTP as a substrate, a 20% decrease in enzymatic activity and a 50% increase in binding affinity of Mt-PhoH2 were observed. The substrates ADP and GDP inhibit the ATPase and GTPase activity of Mt-PhoH2. CD spectroscopy showed the dominance of alpha helix in the secondary structure of Mt-PhoH2, and this structural pattern was altered upon addition of ATP and GTP. In silico inhibitor screening revealed ML141 and NAV_2729 as two potential inhibitors of the catalytic activity of Mt-PhoH2. Mt-PhoH2 is essential for mycobacterial growth as its knockdown strain showed a decreased growth effect. Overall, the present article emphasizes the factors essential for the proper functioning of Mt-PhoH2 which is a participant in the toxin-antitoxin machinery and may also play an important role in phosphate starvation.

Prevalencia de osteopenia del prematuro antes y después de la implementación de una estrategia temprana de manejo fosfocálcico / Prevalence of osteopenia of prematurity before and after implementing an early strategy with the use of calcium and phosphate

Introducción. Con el uso de la nutrición parenteral agresiva en recién nacidos de muy bajo peso, se detectaron alteraciones del metabolismo fosfocálcico. En 2016 se implementó una estrategia de prevención a través del monitoreo fosfocálcico y su suplementación temprana. El objetivo fue estudiar si esta estrategia disminuye la prevalencia de osteopenia e identificar factores de riesgo asociados. Población y métodos. Estudio cuasiexperimental que comparó la prevalencia de osteopenia entre dos grupos: uno después de implementar la estrategia de monitoreo y suplementación fosfocálcica (01/01/2017-31/12/2019), y otro previo a dicha intervención (01/01/2013-31/12/2015). Resultados. Se incluyeron 226 pacientes: 133 pertenecen al período preintervención y 93 al posintervención. La prevalencia de osteopenia global fue del 26,1 % (IC95% 20,5-32,3) y disminuyó del 29,3 % (IC95% 21,7-37,8) en el período preintervención al 21,5 % (IC95% 13,6-31,2) en el posintervención, sin significancia estadística (p = 0,19). En el análisis multivariado, el puntaje NEOCOSUR de riesgo de muerte al nacer, recibir corticoides posnatales y el período de intervención se asociaron de manera independiente a osteopenia. Haber nacido luego de la intervención disminuyó un 71 % la probabilidad de presentar fosfatasa alcalina >500 UI/L independientemente de las restantes variables incluidas en el modelo. Conclusión. La monitorización y suplementación fosfocálcica precoz constituye un factor protector para el desarrollo de osteopenia en recién nacidos con muy bajo peso al nacer.

Introduction. With the use of aggressive parenteral nutrition in very low birth weight infants, alterations in calcium and phosphate metabolism were detected. In 2016, a prevention strategy was implemented through calcium phosphate monitoring and early supplementation. Our objective was to study whether this strategy reduces the prevalence of osteopenia and to identify associated risk factors. Population and methods. Quasi-experiment comparing the prevalence of osteopenia between two groups: one after implementing the calcium phosphate monitoring and supplementation strategy (01/01/2017­12/31/2019) and another prior to such intervention (01/01/2013­12/31/2015). Results. A total of 226 patients were included: 133 in the pre-intervention period and 93 in the post-intervention period. The overall prevalence of osteopenia was 26.1% (95% CI: 20.5­32.3) and it was reduced from 29.3% (95% CI: 21.7­37.8) in the pre-intervention period to 21.5% (95% CI: 13.6­31.2) in the post-intervention period, with no statistical significance (p = 0.19). In the multivariate analysis, the NEOCOSUR score for risk of death at birth, use of postnatal corticosteroids, and the intervention period were independently associated with osteopenia. Being born after the intervention reduced the probability of alkaline phosphatase > 500 IU/L by 71%, regardless of the other variables included in the model. Conclusion. Calcium phosphate monitoring and early supplementation is a protective factor against the development of osteopenia in very low birth weight infants.

Complications With Demineralized Bone Matrix, Hydroxyapatite and Beta-Tricalcium Phosphate in Single and Two-Level Anterior Cervical Discectomy and Fusion Surgery.

STUDY DESIGN: Systematic literature review. OBJECTIVES: To analyze the evidence available reporting complications in single or two-level anterior cervical discectomy and fusion (ACDF) using a demineralized bone matrix (DBM), hydroxyapatite (HA), or beta-tricalcium phosphate (ß-TCP). METHODS: A systematic review of the literature using PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov databases was performed in August 2020 to identify studies reporting complications in one or two-level ACDF surgery using DBM, HA, or ß-TCP. The study was reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. RESULTS: A total of 1857 patients were included, 981 male and 876 female, across 17 articles; 5 prospective, and 12 retrospectives. We noted heterogeneity among the included studies concerning the study design and combination of graft materials utilized in them. However, we noted a higher incidence of adjacent segment disease (17.7%) and pseudoarthrosis (9.3%) in fusion constructs using DBM. Studies using ß-TCP reported a higher incidence of pseudoarthrosis (28.2%) and implant failures (17.9%). CONCLUSIONS: Degenerative cervical conditions treated with one or two-level ACDF surgery using DBM, HA, or ß-TCP with or without cervical plating are associated with complications such as adjacent segment disease, dysphagia, and pseudarthrosis. However, consequent to the study designs and clinical heterogeneity of the studies, it is not possible to correlate these complications accurately with any specific graft material employed. Further well-designed prospective studies are needed to correctly know the related morbidity of each graft used for achieving fusion in ACDF.

Trehalose 6-phosphate synthase gene rdtps1 contributes to thermal acclimation in Rhyzopertha dominica.

BACKGROUND: The lesser grain borer (Rhyzopertha dominica), a worldwide primary pest of stored grain, causes serious economic losses and threatens stored food safety. R. dominica can respond to changes in temperature, especially the adaptability to heat. In this study, transcriptome analysis of R. dominica exposed to different temperatures was performed to elucidate differences in gene expression and the underling molecular mechanism. RESULTS: Isoform-sequencing generated 17,721,200 raw reads and yielded 20,416 full-length transcripts. A total of 18,880 (92.48%) transcripts were annotated. We extracted RNA from R. dominica reared at 5 °C (cold stress), 15 °C (cold stress), 27 °C (ambient temperature) and 40 °C (heat stress) for RNA-seq. Compared to those of control insects reared at 27 °C, 119, 342, and 875 differentially expressed genes (DEGs) were identified at 5 °C, 15 °C, and 40 °C, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that pathways associated with "fatty acid metabolism", "fatty acid biosynthesis", "AMPK signaling pathway", "neuroactive ligand receptor interaction", and "longevity regulating pathway-multiple species" were significantly enriched. The functional annotation revealed that the genes encoding heat shock proteins (HSPs), fatty acid synthase (FAS), phospholipases (PLA), trehalose transporter (TPST), trehalose 6-phosphate synthase (TPS), and vitellogenin (Vg) were most likely involved in temperature regulation, which was also validated by RT-qPCR. Seven candidate genes (rdhsp1, rdfas1, rdpla1, rdtpst1, rdtps1, rdvg1, and rdP450) were silenced in the RNA interference (RNAi) assay. RNAi of each candidate gene suggested that inhibiting rdtps1 expression significantly decreased the trehalose level and survival rate of R. dominica at 40 °C. CONCLUSIONS: These results indicated that trehalose contributes to the high temperature resistance of R. dominica. Our study elucidates the molecular mechanisms underlying heat tolerance and provides a potential target for the pest management in R. dominica.

Pseudomonas putida configures Arabidopsis root architecture through modulating the sensing systems for phosphate and iron acquisition.

Iron (Fe) and phosphate (Pi) are two essential nutrients that are poorly available in the soil and should be supplemented either as fertilizers or organic amendments to sustain crop production. Currently, determining how rhizosphere bacteria contribute to plant mineral nutrient acquisition is an area of growing interest regarding its potential application in agriculture. The aim of this study was to investigate the influence of root colonization by Pseudomonas putida for Arabidopsis growth through Fe and Pi nutritional signaling. We found that root colonization by the bacterium inhibits primary root elongation and promotes the formation of lateral roots. These effects could be related to higher expression of two Pi starvation-induced genes and AtPT1, the major Pi transporter in root tips. In addition, P. putida influenced the accumulation of Fe in the root and the expression of different elements of the Fe uptake pathway. The loss of function of the protein ligase BRUTUS (BTS), and the bHLH transcription factors POPEYE (PYE) and IAA-LEUCINE RESISTANT3 (ILR3) compromised the root branching stimulation triggered by bacterial inoculation while the leaf chlorosis in the fit1 and irt1-1 mutant plants grown under standard conditions could be bypassed by P. putida inoculation. The WT and both mutant lines showed similar Fe accumulation in roots. P. putida repressed the expression of the IRON-REGULATED TRANSPORTER 1 (IRT1) gene suggesting that the bacterium promotes an alternative Fe uptake mechanism. These results open the door for the use of P. putida to enhance nutrient uptake and optimize fertilizer usage by plants.