Microalgae cultivation trials in a membrane bioreactor operated in heterotrophic, mixotrophic, and phototrophic modes using ammonium-rich wastewater: The study of fouling.

In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem.

Enhanced growth and differentiation of neural stem cells on alginate/collagen/reduced graphene oxide composite hydrogel incorporated with lithium chloride.

Introduction: Cell transplantation with hydrogel-based carriers is one of the advanced therapeutics for challenging diseases, such as spinal cord injury. Electrically conductive hydrogel has received much attention for its effect on nerve outgrowth and differentiation. Besides, a load of neuroprotective substances, such as lithium chloride can promote the differentiation properties of the hydrogel. Methods: In this study, alginate/collagen/reduced graphene oxide hydrogel loaded with lithium chloride (AL/CO/rGO Li+) was prepared as an injectable cell delivery system for neural tissue regeneration. After determining the lithium-ion release profile, an MTT assay was performed to check neural viability. In the next step, real-time PCR was performed to evaluate the expression of cell adhesion and neurogenic markers. Results: Our results showed that the combination of collagen fibers and rGO with alginates increased cell viability and the gene expression of collagen-binding receptor subunits such as integrin α1, and ß1. Further, rGO contributed to the controlled release of lithium-ion hydrogel in terms of its plenty of negatively charged functional groups. The continuous culture of NSCs on AL/CO/rGO Li+ hydrogel increased neurogenic genes' expressions of nestin (5.9 fold), NF200 (36.8 fold), and synaptophysin (13.2 fold), as well as protein expression of NF200 and synaptophysin after about 14 days. Conclusion: The simultaneous ability of electrical conduction and lithium-ion release of AL/CO/rGO Li+ hydrogel could provide a favorable microenvironment for NSCs by improving their survival, maintaining cell morphology, and expressing the neural marker. It may be potentially used as a therapeutic approach for stem cell transplantation in a spinal cord injury.

One-year oral health outcome of a community-based trial in schoolchildren aged 6-7 years old in Tehran, Iran.

Promoting schoolchildren's oral health is important, particularly in developing countries. This study was conducted to monitor the oral health of schoolchildren aged 6-7 years old following the implementation of an oral health promotion program in Tehran, Iran. The protocol was registered in the Iranian Registry of Clinical Trials (Code: IRCT20090307001749N4). A cluster random sampling method was applied, and the schools were randomly allocated to intervention and control groups. An intervention package consisting of a one-day workshop for parents and supervised toothbrushing for children was employed. In both groups, the Caries Assessment Spectrum and Treatment (CAST) and Oral Hygiene Index Simplified (OHI-S) were evaluated at baseline and at one-year follow-up in addition to the questionnaire data. Clinical data were collected by calibrated examiners at both intervals (Kappa = 89.8%, 87.68%) and analyzed using the SPSS software ver. 22.0. Of 739 children included at baseline, 593 were re-examined after one year (response rate = 74%). According to the Generalized Estimating Equation (GEE) analysis, considering the confounding effect of time, significantly more children in the control group had deciduous molars with a score of 3 and higher compared to the intervention group (OR = 1.79; 95% CI:1.17-2.73, p = 0.007). The oral hygiene status of the children significantly improved in the intervention group compared to the controls (B = -0.27; 95% CI: -0.45 --0.08, p = 0.005). After one year, the improvement in the oral health-related attitude of parents and children's oral health behavior was marginally significant in the intervention group compared to the control group [0.2 (0.17) vs. -0.13 (0.05), p = 0.096] and [0.06 (0.06) vs. -0.05 (0.04), p = 0.09], respectively. However, the impact on the oral health-related knowledge and self-reported behavior of the parents was not significant. In the intervention group, children had less caries and a better oral hygiene status compared to the controls after one year.

Plant-derived extracellular vesicles: a novel nanomedicine approach with advantages and challenges.

BACKGROUND: Many eukaryote cells produce membrane-enclosed extracellular vesicles (EVs) to establish cell-to-cell communication. Plant-derived EVs (P-EVs) contain proteins, RNAs, lipids, and other metabolites that can be isolated from the juice, the flesh, and roots of many species. METHODS: In the present review study, we studied numerous articles over the past two decades published on the role of P-EVs in plant physiology as well as on the application of these vesicles in different diseases. RESULTS: Different types of EVs have been identified in plants that have multiple functions including reorganization of cell structure, development, facilitating crosstalk between plants and fungi, plant immunity, defense against pathogens. Purified from several edible species, these EVs are more biocompatible, biodegradable, and extremely available from many plants, making them useful for cell-free therapy. Emerging evidence of clinical and preclinical studies suggest that P-EVs have numerous benefits over conventional synthetic carriers, opening novel frontiers for the novel drug-delivery system. Exciting new opportunities, including designing drug-loaded P-EVs to improve the drug-delivery systems, are already being examined, however clinical translation of P-EVs-based therapies faces challenges. CONCLUSION: P-EVs hold great promise for clinical application in the treatment of different diseases. In addition, despite enthusiastic results, further scrutiny should focus on unravelling the detailed mechanism behind P-EVs biogenesis and trafficking as well as their therapeutic applications. Video Abstract.

Caries incidence of the first permanent molars according to the Caries Assessment Spectrum and Treatment (CAST) index and its determinants in children: a cohort study.

BACKGROUND: There are limited information on caries incidence, especially from developing countries, the aim of the present study was to explore caries incidence in the first permanent molar teeth according to the CAST index in 7- to 8-year-old-children and its socio-demographic, oral health related and diet determinants. METHODS: A multi-stage cluster random sample of 7-8 years old children was applied in Tehran, Iran. The oral examination using the CAST index and the Oral Hygiene Index-Simplified (OHI-S) performed by trained dentists in 2017 and 2019 calibrated with an expert (Kappa of 0.89 and 0.76, respectively). A 3-day food record was used to record sugary snacks consumption. Oral health related knowledge of the parents was assessed using a valid and reliable self-administered questionnaire. The data were analyzed using the SPSS software version 23.0 and descriptive and analytical statistics including the negative binomial regression was applied. RESULTS: Two hundred and ninety schoolchildren aged 7-8 years old were followed up for two years. All of them had complete data obtained via oral examination and questionnaires. The annual caries incidence rate was 0.16 and 53% (95% CI 47.4-58.9) of the children developed at least one new dental caries (enamel or dentine) during two years. Multi-variate analysis revealed that the children of mothers with high school education or diploma (IRR = 1.47, 95% CI 1.02-2.12; p = 0.04) and those with low socio-economic status (IRR = 1.86, 95% CI 1.27-2.73; p < 0.001) were more likely to develop caries. There was no significant association between gender, father's educational level, child birth order, housing area per person, OHI-S score, oral health knowledge of parents, and sugary snacks consumption per day and caries increment at an individual level. CONCLUSION: This 2-year longitudinal study on 7- to 8-year-old children showed that caries incidence according to the CAST index was associated with socio-economic status and mother education but not associated with having 2 or more sugary snack per day and oral hygiene status.

Effect of an Oral Health Promotion Program Including Supervised Toothbrushing on 6 to 7-Year-Old School Children: A Randomized Controlled Trial.

OBJECTIVES: The purpose was to evaluate the impact of an oral health promotion program including supervised toothbrushing and educational packages for parents on parent's knowledge and oral health status of 6- to 7-year-old schoolchildren. MATERIALS AND METHODS: A multi-stage cluster random sampling method was applied, and schools were allocated to intervention and control groups. After ethical clearance and baseline evaluation, an intervention package consisting of supervised toothbrushing at the school setting, an educational package for parents, and a home package containing toothbrush and fluoridated toothpaste (1000 parts-per-million) were delivered. A post-intervention evaluation was performed after one month on parents' oral health knowledge and oral hygiene of children using the Oral Hygiene Index Simplified (OHI-S). Schools were considered as a unit of randomization, and a generalized estimating equation (GEE) analysis was performed to apply the cluster effect. Descriptive and analytical analyses were performed using SPSS 22 software. RESULTS: Overall, 701 subjects were re-examined (response rate of 95%). At the one-month follow-up, being in the intervention group (P<0.001, B=-0.028, 95% confidence interval (CI)= -0.33, -0.23) and having higher socioeconomic status [P=0.01, B=-0.12, 95% CI=-0.22, -0.03) were significantly associated with improved oral hygiene status. In the post-test evaluation, parents' knowledge improvement score regarding oral health in the intervention group was not statistically different from that of the controls (0.51 vs. 0.23). However, the ΔOHI-S improved in the post-test evaluation (-0.27±0.02 vs. 0.02±0.02; P<0.001). CONCLUSION: Children showed improved oral hygiene status, as measured by the OHI-S, after the program consisting of supervised toothbrushing.

Oral health of 6-7 year-old children according to the Caries Assessment Spectrum and Treatment (CAST) index.

BACKGROUND: The index of Caries Assessment Spectrum and Treatment (CAST) reveals a range of caries development from a non-cavitated status to advanced lesions. The aim of the present study was to explore the oral health status of 6- to 7-year-old children based on the CAST index in relation to oral health knowledge and background determinants. METHODS: A multi-stage cluster random sampling method was applied and after ethical clearance, clinical examination was performed (Kappa = 0.89). The status of caries and oral hygiene was recorded according to the CAST index and OHI-Simplified (OHI-S) index, respectively. A self-administered questionnaire was used to collect the data of parental knowledge of oral health. SPSS version 22.0 was used for data analysis and p-value less than 0.05 were considered significant. RESULTS: Seven hundred and thirty-nine children and their parents in 24 schools participated in this study (88%), of whom 48.6% were boys and the rest were girls. In permanent molars, a healthy status (code 0-2) was observed in 89.3-93.7% of the teeth. In primary molar teeth, dentinal lesions ranged from 25.3 to 31.2%, the prevalence of pulp involvement was between 2.9 and 10.5%, and less than 1% had abscess/fistula. Serious morbidity (codes 6 and 7) were more common in the first primary molars than the second ones. Multi-variable logistic regression analysis indicated that children with a low level of father's education were 2.45 times more likely to have a CAST score of 3 and higher (95% CI 1.35-4.46, p = 0.003) compared to children whose fathers had academic education. For each one-unit increment of OHI_S, the likelihood of a CAST score 3 and higher in primary dentition increased by 1.77 times (OR = 1.77; 95% CI 1.08-2.93, p = 0.02). CONCLUSION: The consequences of dental caries including abscess and fistula were more prevalent in the first and second primary teeth. There was a significant correlation between a CAST score of 3 and higher with father's education (as an indicator of social rank) and oral hygiene status. The CAST index is a useful and practical index in epidemiological surveys.

Effects of temperature and mixing modes on the performance of municipal solid waste anaerobic slurry digester.

PURPOSE: Anaerobic digestion is a promising technology for simultaneous treatment of biodegradable organic matter of municipal solid waste (MSW) and production of renewable energy. Mixing modes and temperature have influences on biogas production in anaerobic digesters treating MSW. Therefore, in this study, digester was operated at different modes of mixing and temperatures to obtain design criteria. METHODS: The experiments were carried out in a semi-continuous digester. In the first part of the investigation, temperature was set at 25, 28, 31 and 34 °C. During this step, digester content was mixed in an intermittent mode by mechanical mixers. In the second part of the study, mixing condition of the digester was set at various modes: continuous, intermittent (15 min on and 30 min off) and minimal (twice in a batch). RESULTS: Digestion with a temperature in this range resulted in biogas yield of 0.23-0.33 m3 biogas/kg VS, with a methane content of 60.2-71.8% in biogas. The methane content and yield decreased with reduction of digestion temperature. However, this reduction was almost negligible from 34 to 31 °C. In addition, in comparison to intermittent mixing, continuous and minimal mixing modes reduced the biogas production by 40% and 50%, respectively. Therefore, in this digester greatest biogas yield of 0.33 ± 0.02 m3 biogas/kg VS were obtained at 34 °C and intermittent mixing mode. CONCLUSIONS: Based on the data obtained from this study, temperature in the range of 31-34 °C and intermittent mixing is suggested as a base for design purposes.

Directly injected native bone-marrow stem cells cannot incorporate into acetaminophen-induced liver injury.

The paucity of liver donation highlights the use of cell-based strategies for end-stage liver failure. We recently showed that bone marrow-derived aggregates (BMDAs) can completely restore the hematopoietic system in gamma-irradiated mice. These aggregates are stem and progenitor cells in the bone marrow (BM), composed of both hematopoietic and non-hematopoietic lineages. Furthermore, reports showed that resident BM cells migrate to the liver and integrate themselves into the tissue in small numbers. Hence, we hypothesized that direct delivery of BMDAs to the damaged liver might enhance the integration of BM cells in the liver because of its stemness property, intact BM architecture, the physical proximity of these niche-like structures to the damaged sites and the existence of liver paracrine factors. To this aim, we made an acute liver model by intraperitoneal injection of acetaminophen. Then, GFP-expressing BMDAs were intrahepatically injected. Despite the detection of GFP-expressing cells five days after intrahepatic injection, these cells were not detectable at days 15 and 60, indicating that the puzzle of BM cell integration in the liver still has more missing pieces other than stemness, physical proximity, and paracrine factors. Actually, it seems that even intact BM structures need further signals to be qualified for integration.

The synergistic effect of Selenium (selenite, -SeO32-) dose and irradiance intensity in Chlorella cultures.

Microalgae are able to metabolize inorganic selenium (Se) to organic forms (e.g. Se-proteins); nevertheless at certain Se concentration culture growth is inhibited. The aim of this work was to confirm the hypothesis that the limit of Se tolerance in Chlorella cultures is related to photosynthetic performance, i.e. depends on light intensity. We studied the relation between the dose and irradiance to find the range of Se tolerance in laboratory and outdoor cultures. At low irradiance (250 µmol photons m-2 s-1), the daily dose of Se below 8.5 mg per g of biomass (<20 µM) partially stimulated the photosynthetic activity (relative electron transport rate) and growth of Chlorella cultures (biomass density of ~1.5 g DW L-1) compared to the control (no Se added). It was accompanied by substantial Se incorporation to microalgae biomass (~0.5 mg Se g-1 DW). When the Se daily dose and level of irradiance were doubled (16 mg Se g-1 DW; 500 µmol photons m-2 s-1), the photosynthetic activity and growth were stimulated for several days and ample incorporation of Se to biomass (7.1 mg g-1 DW) was observed. Yet, the same Se daily dose under increased irradiance (750 µmol photons m-2 s-1) caused the synergistic effect manifested by significant inhibition of photosynthesis, growth and lowered Se incorporation to biomass. In the present experiments Chl fluorescence techniques were used to monitor photosynthetic activity for determination of optimal Se doses in order to achieve efficient incorporation without substantial inhibition of microalgae growth when producing Se-enriched biomass.