Digital health literacy and health behaviors of eighth and ninth graders from Germany

Background

Due to the high availability and use of digital media, health-related information is increasingly shifting into the digital space. While there are increasing empirical findings on general health literacy (HL), there is a lack of evidence on digital HL in adolescence and its association with health behavior.

Methods

A cross-sectional study of 490 secondary school students (grades eight and nine) from the federal state of Hesse was conducted from October 2019 to February 2020. Digital HL was assessed using five subscales of the Digital Health Literacy Instrument (DHLI), while consumption of fruits, vegetables, soft drinks, and weekly physical activity were used as indicators of health behavior. In addition to gender and grade level, subjective social status (SSS) was used as a social characteristic. Univariate, bivariate, and multivariate analyses were performed, with binary-logistic regression adjusted for gender and SSS.

Results

Across all items, the percentage of adolescents reporting difficulties in acquiring and dealing with digital health information ranges from 15.3 % to 37.5 %. Stratified by social characteristics, gender and socioeconomic differences were found with girls and respondents reporting a lower SSS more often showing a limited digital HL. Adolescents with moderate and low digital HL report higher levels of low physical activity, non-daily fruit and daily soft drink consumption. Depending on the health behavior, different relationship patterns can be observed for the dimensions of digital HL.

Conclusions

The findings suggest a need for interventions to promote digital HL among adolescents, particularly for those of low SSS. In this context, the differential relationship patterns with health behaviors provide an avenue for the development of specific interventions.

A Model of Aerobic and Anaerobic Metabolism of Hydrogen in the Extremophile Acidithiobacillus ferrooxidans

Hydrogen can serve as an electron donor for chemolithotrophic acidophiles, especially in the deep terrestrial subsurface and geothermal ecosystems. Nevertheless, the current knowledge of hydrogen utilization by mesophilic acidophiles is minimal. A multi-omics analysis was applied on Acidithiobacillus ferrooxidans growing on hydrogen, and a respiratory model was proposed. In the model, [NiFe] hydrogenases oxidize hydrogen to two protons and two electrons. The electrons are used to reduce membrane-soluble ubiquinone to ubiquinol. Genetically associated iron-sulfur proteins mediate electron relay from the hydrogenases to the ubiquinone pool. Under aerobic conditions, reduced ubiquinol transfers electrons to either cytochrome aa ₃ oxidase via cytochrome bc ₁ complex and cytochrome c ₄ or the alternate directly to cytochrome bd oxidase, resulting in proton efflux and reduction of oxygen. Under anaerobic conditions, reduced ubiquinol transfers electrons to outer membrane cytochrome c (ferrireductase) via cytochrome bc ₁ complex and a cascade of electron transporters (cytochrome c ₄, cytochrome c ₅₅₂, rusticyanin, and high potential iron-sulfur protein), resulting in proton efflux and reduction of ferric iron. The proton gradient generated by hydrogen oxidation maintains the membrane potential and allows the generation of ATP and NADH. These results further clarify the role of extremophiles in biogeochemical processes and their impact on the composition of the deep terrestrial subsurface.

Can Sulfate Be the First Dominant Aqueous Sulfur Species Formed in the Oxidation of Pyrite by Acidithiobacillus ferrooxidans?

According to the literature, pyrite (FeS₂) oxidation has been previously determined to involve thiosulfate as the first aqueous intermediate sulfur product, which is further oxidized to sulfate. In the present study, pyrite oxidation by Acidithiobacillus ferrooxidans was studied using electrochemical and metabolic approaches in an effort to extend existing knowledge on the oxidation mechanism. Due to the small surface area, the reaction rate of a compact pyrite electrode in the form of polycrystalline pyrite aggregate in A. ferrooxidans suspension was very slow at a spontaneously formed high redox potential. The slow rate made it possible to investigate the oxidation process in detail over a term of 100 days. Using electrochemical parameters from polarization curves and levels of released iron, the number of exchanged electrons per pyrite molecule was estimated. The values close to 14 and 2 electrons were determined for the oxidation with and without bacteria, respectively. These results indicated that sulfate was the dominant first aqueous sulfur species formed in the presence of bacteria and elemental sulfur was predominantly formed without bacteria. The stoichiometric calculations are consistent with high iron-oxidizing activities of bacteria that continually keep the released iron in the ferric form, resulting in a high redox potential. The sulfur entity of pyrite was oxidized to sulfate by Fe³⁺ without intermediate thiosulfate under these conditions. Cell attachment on the corroded pyrite electrode surface was documented although pyrite surface corrosion by Fe³⁺ was evident without bacterial participation. Attached cells may be important in initiating the oxidation of the pyrite surface to release iron from the mineral. During the active phase of oxidation of a pyrite concentrate sample, the ATP levels in attached and planktonic bacteria were consistent with previously established ATP content of iron-oxidizing cells. No significant upregulation of three essential genes involved in energy metabolism of sulfur compounds was observed in the planktonic cells, which represented the dominant biomass in the pyrite culture. The study demonstrated the formation of sulfate as the first dissolved sulfur species with iron-oxidizing bacteria under high redox potential conditions. Minor aqueous sulfur intermediates may be formed but as a result of side reactions.

Kinetics of anaerobic elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans and protein identification by comparative 2-DE-MS/MS

Elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans was investigated. The apparent Michaelis constant for ferric iron was 18.6 mM. An absence of anaerobic ferric iron reduction ability was observed in bacteria maintained on elemental sulfur for an extended period of time. Upon transition from ferrous iron to elemental sulfur medium, the cells exhibited similar kinetic characteristics of ferric iron reduction under anaerobic conditions to those of cells that were originally maintained on ferrous iron. Nevertheless, a total loss of anaerobic ferric iron reduction ability after the sixth passage in elemental sulfur medium was demonstrated. The first proteomic screening of total cell lysates of anaerobically incubated bacteria resulted in the detection of 1599 protein spots in the master two-dimensional electrophoresis gel. A set of 59 more abundant and 49 less abundant protein spots that changed their protein abundances in an anaerobiosis-dependent manner was identified and compared to iron- and sulfur-grown cells, respectively. Proteomic analysis detected a significant increase in abundance under anoxic conditions of electron transporters, such as rusticyanin and cytochrome c(552), involved in the ferrous iron oxidation pathway. Therefore we suggest the incorporation of rus-operon encoded proteins in the anaerobic respiration pathway. Two sulfur metabolism proteins were identified, pyridine nucleotide-disulfide oxidoreductase and sulfide-quinone reductase. The important transcription regulator, ferric uptake regulation protein, was anaerobically more abundant. The anaerobic expression of several proteins involved in cell envelope formation indicated a gradual adaptation to elemental sulfur oxidation.

Kinetic constant variability in bacterial oxidation of elemental sulfur

Wide ranges of growth yields on sulfur (from 2.4 x 10(10) to 8.1 x 10(11) cells g(-1)) and maximum sulfur oxidation rates (from 0.068 to 1.30 mmol liter(-1) h(-1)) of an Acidithiobacillus ferrooxidans strain (CCM 4253) were observed in 73 batch cultures. No significant correlation between the constants was observed. Changes of the Michaelis constant for sulfur (from 0.46 to 15.5 mM) in resting cells were also noted.

Purification and Some Properties of Thiosulfate Dehydrogenase fromAcidithiobacillus ferrooxidans

Thiosulfate dehydrogenase was purified from Acidithiobacillus ferrooxidans using three purification steps. The purification procedure involved ammonium sulfate fractionation, ion-exchange chromatography, and gel permeation chromatography. Specific activity of the purified enzyme (after IEC) was 3.26 nkat/mg, and yield of the enzyme was 78%. The purity of the enzyme was checked by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme is a tetramer composed of four probably identical subunits of relative molecular weight 45,000. The pH optimum of the enzyme reaction in the direction of substrate oxidation was found to be 3.0. The isoelectric point of the enzyme was 8.3. Enzyme activity was found to be particularly sensitive to the histidine-selective reagent diethylpyrocarbonate. Reagents selective for arginine, cysteine, and tryptophane had no effect on enzyme activity.

Proteomic and bioinformatic analysis of iron- and sulfur-oxidizing Acidithiobacillus ferrooxidans using immobilized pH gradients and mass spectrometry

A comparative analysis of the protein composition of Acidithiobacillus ferrooxidans cells grown on elemental sulfur and ferrous iron was performed. A newly developed protocol involving immobilized pH gradients, improved protein reduction, mass spectrometry protein identification and full genome sequence information was applied. This approach resulted in more than 1300 protein spots displayed in broad and basic pH ranges, the best A. ferrooxidans proteome resolution to date. A comparative image analysis revealed that the proteome was significantly influenced by the growth type, and allowed for the detection of many physiologically important proteins. Among them were sulfate adenylyltransferase and sulfide dehydrogenase, which are involved in sulfate assimilation and sulfide metabolism, respectively. Many other proteins were related to important processes like cell attachment and electron transport. Co-migration of phosphate and sulfate transport proteins was also observed.

Use of immobilized cytochrome c as a ligand for affinity chromatography of thiosulfate dehydrogenase from Acidithiobacillus ferrooxidans

Three matrices were used for immobilizing the cytochrome c: Sepharose CL-4B, Silasorb SPH amine and a laboratory-prepared new matrix based on crosslinked triazine (2,4,6-tris(aminoethylamine)-1,3,5-triazine) (TAT). Cytochrome c was immobilized on the matrices by several procedures and the amount of incorporated cytochrome c was determined. Cytochrome c immobilized on Sepharose CL-4B with periodate activation, cytochrome c immobilized on Silasorb-amine with carbodiimide activation and cytochrome c immobilized on crosslinked triazine were suitable for purification of thiosulfate dehydrogenase from Acidithiobacillus ferrooxidans. The yield with all matrices was about 90%. The purification factor of the above matrices was about 15. A new matrix based on TAT with cytochrome c represented a suitable way for thiosulfate dehydrogenase purification.

Purification and Some Properties of Isocitrate Dehydrogenase fromParacoccus denitrificans

NADP-dependent isocitrate dehydrogenase (ICDH) from the bacterium Paracoccus denitrificans was purified to homogeneity. The purification procedure involved ammonium sulphate fractionation, ion exchange chromatography, and gel permeation chromatography. The specific activity of purified ICDH was 801 nkat/mg, the yield of the enzyme 58%. The purity of the enzyme was checked by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. ICDH is a dimer composed of two probably identical subunits of relative molecular weight 90,000. The pH optimum of the enzyme reaction in the direction of substrate oxidation was found to be 5.6; the presence of Mn2+ is essential for enzyme activity. The absorption and fluorescence spectra of the homogeneous enzyme were measured as well.

Formation of iodinin by a strain of Acidithiobacillus ferrooxidans grown on elemental sulfur

The presence of the pigment iodinin, an Acidithiobacillus ferrooxidans culture metabolite, was demonstrated after growth of bacteria on elemental sulfur. The structure of iodinin was confirmed by X-ray structure analysis; its physiological role is discussed.

Application of capillary zone electrophoresis to study the properties of rhodanese from Acidithiobacillus ferrooxidans

A new capillary zone electrophoretic method was applied to the assay of enzymic activity of rhodanese from Acidithiobacillus ferroxidans. The enzyme activity determined by capillary zone electrophoresis was compared with that determined by discontinuous spectrophotometry, the values obtained being in good agreement. The method was also used to evaluate Michaelis constants of cyanide and thiocyanate as substrates; a new approach was developed to solve the problem with variable ionic strength of the samples. The pH and temperature optima for the enzyme were also determined.

Cytochrome c forms complexes and is partly reduced at interaction with GPI-anchored alkaline phosphatase

Cytochrome (cyt) c forms complexes, undergoes a conformational change and becomes partly reduced at interaction with membrane anchored alkaline phosphatase (AP), a glycoprotein which is released into the body fluid in forms differing in hydrophobicity. The proportion of products formed in the mixtures depends on pH, ionic strength, temperature and the buffer composition. The reaction terminates in an equilibrium between cyt c(FeII) and other cyt c conformers. Optimal conditions for the rate of the reaction are 100 mM glycine/NaOH, pH 9.7-9.9, at which 68-74% of cyt c is found in the reduced state. The interaction affects compactness of the haem cleft as shown by changes induced in CD spectra of the Soret region and changes in optical characteristics of phenylalanine, tyrosine and tryptophan residues. Differential scanning calorimetry of AP+cyt c mixtures revealed a creation of at least two types of complexes. A complex formed by non-coulombic binding prevails at substoichiometric AP/cyt c ratios, at higher ratios more electrostatic attraction is involved and at 1:1 molar ratio an apparent complexity of binding forces occurs. The rapid phase of the cyt c(FeII) formation depends on the presence of the hydrophobic alkylacylphosphoinositol (glycosylphosphatidylinositol) moiety, the protein part of the enzyme participates in an electrostatic and much slower phase of cyt c(FeII) creation. The results show that non-coulombic interaction may participate at interaction of cyt c with cellular proteins.

Determination of pyrroloquinoline quinone by capillary zone electrophoresis

A new method for the determination of pyrroloquinoline quinone by capillary zone electrophoresis has been developed. Separation conditions have been optimised with the respect to different parameters including pH and ionic strength of the background electrolyte, separation voltage and temperature of the capillary. A buffer consisting of 50 mM beta-alanine-HCl pH 3.0 was found to be the most suitable electrolyte for this separation. An applied voltage of 25 kV (negative polarity) and a temperature of 25 degrees C gave the best analysis of pyrroloquinoline quinone. The linear detection range for concentration versus peak area for the assay is from 5 to 500 microM (correlation coefficient 0.9998) with a detection limit of 0.1-0.2 microM. The inter-day reproducibility of the peak area was 2.5% and the inter-day reproducibility of the migration time was below 0.18%.

Evidence of complex formation between alkaline phosphatase and a pro-apoptotic hemoprotein cytochrome c

Two proteins, alkaline phosphatase (AP) and cytochrome c (cyt c) which seem to be involved in the apoptotic cell death program were examined on their interaction. Intestinal AP affects ferricytochrome c (cyt c(FeIII)) by changing its optical properties, redox state and conformation. The effect proceeded over the course of hours with a gradual decrease in free cyt c(FeIII) as the AP concentration increased. A heme containing high molecular species was created in the first stage of interaction of the proteins in neutral, acidic (pH 2.6), alkaline (pH 8.3), low ionic strength (10 mmol/l phosphate), and high ionic strength (0.5 mol/l NaCl) media. Further complexation was favored by higher pH values and temperature. Differential scanning calorimetry revealed a decrease in enthalpy of the thermodenaturation temperature (Tm) of cyt c at 84.5 degrees C due to the AP addition. Increments of AP in the mixtures resulted in the appearance of Tm peaks at 68 degrees C and 61 degrees C. Electrophoretic analysis of the commercial samples of intestinal APs showed main fractions from 63.2 kDa to 72.9 kDa and from 172.9 up to 179.0 kDa. Changes in positions and intensities of the bands were detected upon longer incubation (24 h) with cyt c. The electrophoretic pattern of the bacterial AP was homogeneous with one fraction of 43.7 kDa showing no alteration due to the cyt c presence. Gel permeation chromatography of incubated mixtures of intestinal APs and cyt c confirmed the creation of new heme containing complexes.

Determination of rhodanese enzyme activity by capillary zone electrophoresis

A new sensitive method has been developed for the determination of rhodanese activity. The enzymatic reactions were carried out directly in thermostatted autosampler vials and the formation of SCN- was monitored by sequential capillary zone electrophoretic runs. The determinations were performed in a 75-micron fused-silica capillary using 0.1 M beta-alanine-HCl (pH 3.50) as a background electrolyte, a separation voltage of 18 kV (negative polarity), a capillary temperature of 25 degrees C and direct detection at 200 nm. Short-end injection or long-end injection procedures were used for sample application. The method is rapid, able to be automated and requires only small amounts of sample and substrates, which is especially important in the case of highly toxic cyanide. The developed capillary electrophoretic method also has great potential for thiocyanate determinations in other applications.

Use of thiopropyl sepharose for the synthesis of an adsorbent for the affinity chromatography of glutathione S-transferase

Thiopropyl Sepharose 6B in the 2-thiopyridyl-activated form was used for the reversible immobilisation of reduced glutathione (GSH). The resulting affinity matrix was successfully tested as a sorbent for the partial purification of glutathione S-transferase (GST) from pig kidney. The specific elution of the enzyme was performed with 10 mM GSH in Tris-HCl buffer (pH 7.8), non-specific elution with 20 mM dithiotreitol (DTT) in the same buffer.

Detection of quinoproteins after electrophoresis in the presence of urea or SDS

A method for the direct detection of quinoproteins in gels after electrophoresis in the presence of urea or SDS has been developed. The conditions of sample preparation and detection were optimized to achieve maximum sensitivity. The method is suitable for the detection of quinoproteins in complex protein mixtures as well as for the characterization of certain enzyme preparations.

Improved chromatographic purification of pea seedlings diamine oxidase

An improved and simplified purification procedure has been developed for the isolation of diamine oxidase from pea seedlings (DAO EC 1.4.3.6). It involves ammonium sulphate precipitation, hydrophobic interaction chromatography, ion-exchange chromatography and size-exclusion chromatography. The homogeneity of the final enzyme preparations and molecular weight were determined by size-exclusion chromatography and by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS PAGE). The isoelectric point of 7.35 +/- 0.05 was determined by chromatofocusing and by polyacrylamide gel isoelectric focusing.

Purification and properties of malate dehydrogenase from Paracoccus denitrificans

Affinity chromatography on immobilized Cibacron Blue (Matrex Gel Blue A) gel permeation chromatography on UltroPac TSK G 3000 SWG column and ion-exchange chromatography on "Mono Q" column were used to purify the malate dehydrogenase (MDH) from P. denitrificans to electrophoretic homogeneity. The last two purification steps were performed in FPLC system. The enzyme having a specific activity of about 2300 nkat/mg protein was obtained with an approximate 70% yield. MDH is a dimer with a molecular mass of 80,000 +/- 10,000 and an isoelectric point of 4.85 +/- 0.05. Absorption, fluorescence and CD-spectra were also measured and basic kinetic parameters were obtained for the homogeneous enzyme. The present paper also suggests the possibility of using the prepared enzyme for the determination of aspartate transferase (AST) in blood serum.