Evaluation of Flow Rate, pH, and Buffering Capacity of Saliva in Children with Caries, Fluorosis, and Caries with Fluorosis

Background

Saliva is one of the most important aids in the diagnosis of various oral diseases. Few physicochemical properties of saliva such as flow rate, pH, and buffering capacity often vary with the occurrence of dental caries, fluorosis, and other systemic conditions.

Purpose

The aim of the study was to evaluate the relationship between the salivary flow rate, pH, and buffering capacity in healthy children, children with caries, children with fluorosis, and children with both caries + fluorosis.

Materials and methods

The study population consisted of 144 children aged 7-14 years and were divided into four groups of 36 children each. Group I, 36 healthy children with no caries and fluorosis; group II, 36 children with caries (dmfs ≤ 10); group III, 36 children with fluorosis (moderate to severe); and group IV, 36 children with caries + fluorosis. Unstimulated saliva is collected from all the selected subjects and evaluated for the salivary flow rate, pH, and buffering capacity. The recorded data were tabulated and statistically analyzed using a paired t-test.

Results

The mean salivary flow rate and buffering capacity were found to be highest in group III when compared with all the other groups. The mean pH was greater in group I when compared with groups I, II, and III.

Conclusion

The physicochemical properties of saliva like pH, buffering capacity, and salivary flow rate alter with caries and fluorosis conditions. Hence, more clinical and laboratory studies are needed to determine the exact relationship between these physicochemical properties of saliva in dental caries and fluorosis.

How to cite this article

E RR, S S, M K, et al. Evaluation of Flow Rate, pH, and Buffering Capacity of Saliva in Children with Caries, Fluorosis, and Caries with Fluorosis. Int J Clin Pediatr Dent 2023;16(4):587-590.

Buffering capacity of submerged macrophytes against nutrient pulses increase with its coverage in shallow lakes

Submerged macrophytes can improve water quality and buffer the effects of external nutrient loading, which helps to maintain a clear-water state in shallow lakes. We constructed 12 large enclosures with contrasting coverages (treatments) of submerged macrophytes (SMC) to elucidate their buffering capacity and resilience to nutrient pulses. We found that aquatic ecosystems with high SMC had higher buffering capacity and resilience, vice versa, i. e, the enclosures with high SMC quickly buffered the nutrient pulse and rebounded to clear-water state after a short stay in turbid-water state dominated by algae, while the treatments with low SMC could not fully buffer the pulse and rebound to clear-water state, and they slowly entered the transitional state after staying in turbid-water state. This means that the enclosures with high SMC had a better water quality than those with low SMC, i.e., the levels of nutrients and Chl-a were lower in the treatments with high plant coverage. In addition, plant coverage had a significantly positive buffering effect against nitrogen and phosphorus pulses, i.e., the nutrient concentrations in the treatments with high SMC took shorter time to return to the pre-pulse level. Overall, our results evidenced that the higher that the SMCs is, the better is the water quality and buffering capacity against nutrient pulses, i.e. the more stable is the clear-water state. However, low SMC may not be able to resist the impact of such strong nutrient pulse. Our results provide reference and guidance for water pollution control and water ecological restoration.

The changes in the physicochemical properties of calcareous soils and the factors of arsenic (As) uptake by wheat were investigated after the cessation of effluent irrigation for nearly 20 years

It is not known what the buffering capacity of soils and arsenic (As) enrichment by crops is for calcareous agricultural soils after the end of long-term effluent irrigation. In this study, changes in soil physicochemical properties and factors of influencing As uptake by wheat were investigated in agricultural soils where sewage irrigation had been ceased for nearly 20 years. The results showed that the content of CaCO₃ and pH in soil increased compared to the period before the cessation of sewage irrigation, but remained below the soil background value. Furthermore, CaCO₃ is by far the main buffering substance in agricultural soils and indirectly contributes to the increase in pH. The As concentration in the soil was 36.4 ± 34.8 mg/kg, which was 0.56-10.28 times and 0.28-5.18 times higher than the soil background and risk screening values, respectively, but showed a decreasing trend. pH and Fe dissolution were the main reasons for the lower As concentration in the soil. Total As in soil was a better predictor of As in wheat, and soil electrical conductivity (EC) and soil organic matter (SOM) promoted As uptake by wheat. The competitive uptake of As by dissolved Si was an important reason for the mismatch between As concentrations in soil and wheat. This study highlighted the key issues of As transport transformation in soil-wheat systems after cessation of effluent irrigation, using agricultural soils, and provided a reference for soil risk management in agricultural soils in mining areas.

Soil heterogeneity influence on the distribution of heavy metals in soil during acid rain infiltration: Experimental and numerical modeling

Acid rain is a global environmental problem that mobilizes heavy metals in soils, while the distribution and geochemical fraction of heavy metals during acid rain infiltration in heterogeneous soils are still unclear. In this study, we performed column experiments to investigate the distribution and geochemical fraction of Cu, Pb, Ni and Cd in heterogeneously layered soils during continuous acid rain infiltration. Chloride ion used as a conservative tracer was found to be uniformly distributed during acid rain infiltration, showing insignificant preferential flow effects in the column. In contrast, however, the distribution of heavy metals was highly non-uniform, especially in the silty soil at the lower part of the column, indicating a heterogeneous distribution of adsorption capacity. In addition, in the control experiments with neutral rain infiltration, uniform distribution of heavy metals was observed, indicating that the heterogeneous distribution of adsorption coefficient during acid rain infiltration was mainly caused by different pH buffering capacities. A numerical model considering water flow and solute transport was developed, where the average water-solid distribution coefficient (K_d) in Layer 2 was only 1.5-12.5% of that in Layer 1 during acid rain infiltration. The model could predict the variation of heavy metal concentrations in soil with the majority of error less than 35%, confirming that different K_d induced the heterogeneous distribution of heavy metals. In addition, the geochemical fraction of heavy metals in the upper coarse sand layer remained stable, while the acid-extractable fractions in the lower loam and silt loam layer gradually increased. Our findings suggest that soil heterogeneity, especially chemical heterogeneity affected by rainfall acidity, has an important influence on the infiltration, migration and geochemical fraction of heavy metals in soils. This study could help guide the risk assessment of heavy metal-contaminated sites that were polluted by acid rain or landfill leachate.

A comparative evaluation of fracture toughness, flexural strength, and acid buffer capability of a bulk-fill alkasite with high-strength glass-ionomer cement: An in vitro study

BACKGROUND

Although glass-ionomer cement (GIC) has many unique properties and advantages, it still lacks favorable mechanical properties. Cention N is a recent alkasite material with excellent mechanical properties. The purpose of this study was to compare the mechanical properties (fracture toughness [FT] and flexural strength [FS]) and acid buffer capability of an alkasite material to GIC.

MATERIALS AND METHODS

In this in vitro study, a total of 60 samples were prepared using Cention N or GIC. Twenty specimens (n = 10) were prepared using beam-shaped Teflon molds for FS, and twenty specimens (n = 10) were prepared with a similar mold with a notch for FT. These were evaluated on a universal testing machine using a three-point bend test. Twenty (n = 10) disk-shaped specimens were prepared for acid buffer capability. The samples were stored in distilled water for a week. This was followed by immersion in lactic acid with a pH of 4 for calculation of the materials acid buffering capacity at 30 and 60 min from exposure using a pH meter. The data obtained were tabulated and subjected to Kolmogorov-Smirnov test and Shapiro-Wilk test to assess the normal distribution and further analyzed using the Student's t-test to assess the level of significance, P < 0.05 was considered statistically significant.

RESULTS

The mean FT, FS, and acid buffer capability of Cention N were significantly higher than GIC at P < 0.05.

CONCLUSION

The present study surmised that Cention N exhibited higher FT, FS, and acid buffer capability than GIC.

The effects of weathering of coal-bearing stratum on the transport and transformation of DIC in karst watershed

The mining of medium- to high‑sulfur coal in karst areas has led to serious acidification problems in surface water, thus encouraging a re-evaluation of DIC transformation and CO₂ source-sink relationships in karst watersheds. The weathering of limestone and sulfide-rich coal measures jointly influence the pH of the Huatan River in karst areas in Southwest China, which is lower in the rainy season and higher in the dry season. Due to CO₂ degassing, DIC concentration tends to decrease along the flow direction, while δ¹³C-DIC gradually becomes heavier. In general, DIC transformation in the Huatan River is controlled by AMD input, CO₂ degassing, organic matter (OM) degradation, and the dissolution and precipitation balance of carbonate minerals in different seasons. In spring, the mineralization of OM from terrestrial and domestic sewage gradually enhances and replenishes DIC in the water. As the pH increases in this season, the capacity for buffering CO₂ increases. Meanwhile, OM degradation generates a large amount of CO₂ in summer, and carbonic acid begins to dissolve limestone. In autumn, the pH decreases due to the enhanced weathering of sulfide-rich coal measures and the mass input of AMD. Thus, the river shows the ability to drive CO₂ outgassing. In winter, CO₂ degassing gradually weakens, DIC concentration is at its lowest, and δ¹³C-DIC reaches the heaviest value.

Synergy of selective buffering, intermittent pH control and bioreactor configuration on acidogenic volatile fatty acid production from food waste

The production of volatile fatty acids (VFAs) and biohydrogen (bio-H₂) from food waste (FW) by acidogenic process is one of the promising strategies. The present study was performed to evaluate the role of initial (phase I) and intermittent pH (phase II) control strategies utilising combination of sodium hydroxide (NaOH) and sodium carbonate (Na₂CO₃) as buffering/neutralizing agents on VFAs and bio-H₂ production from FW. The study was carried out in two bioreactor configurations (biofilm (UAFBB) and a suspended mode bioreactor (UASB)). Intermittent pH adjustment (phase II) increased hydrolysis and FW acidification compared to the initially adjusted pH (phase I), but had a detrimental influence on bio-H₂ generation in both the studied bioreactor configurations. Combining NaOH and Na₂CO₃ resulted in higher buffering capacity and VFA production. The studied parameters in UAFBB aided in higher VFA (14.05 g/L; 48 h of cycle operation) and bio-H₂ (56%; 12 h of cycle operation) production during phase II and phase I operation, respectively. Overall, the results showed a synergy between the examined parameters, resulting in increased VFA production from FW.

A comprehensive methodology for determining buffering capacity of landfill-mined-soil-like-fractions

The utilization of landfill-mined-soil-like-fractions (LFMSF), which is a major fraction resulting from landfill mining (LFM) activity, is being debated owing to a lack of comprehensive understanding of its characteristics. In this context, based on the physicochemical properties of LFMSF, several of the earlier researchers have opposed its utilization as compost, feedstock in waste-to-energy, and fill material in civil engineering applications. However, it has been noticed that LFMSF consists of required amount of organic matter (OM) and inorganic carbon (IC) to make it suitable as a buffering material that would help to modify/treat geomaterials exhibiting extreme pH values. In this context, determination of its buffering capacity (BC), a parameter that quantifies the buffering potential, becomes essential. However, determination of BC by resorting to the existing protocols is not suggestible mainly due to (i) an extremely narrow range of the pH (3-8) employed, (ii) lack of incorporation of the optimal time required for reaction/pH stabilization (t_pHS), (iii) concern for decomposition of OM during the addition of H⁺/OH^- while experimentation and (iv) heterogeneity associated with the LFMSF unlike the geomaterials that are commonly tested (viz., agricultural soils and compost). Hence, to overcome these limitations, a comprehensive methodology that can be employed for determining the ultimate buffering capacity (BC_u) by establishing appropriate t_pHS (i.e., 200 h) and liquid to solid ratio (i.e., 20), which would eliminate the decomposition of OM over a broad range of pH (i.e., 2-12) has been proposed. Based on the testing of several LFMSF samples collected from unscientifically created landfills/dumpsites and engineered landfills in India, easy-to-use relationships between the (i) reaction time (t) and (ii) physicochemical properties of the samples that influence BC and BC_u, directly or indirectly, have also been proposed.

Biogas production performance and system stability monitoring in thermophilic anaerobic co-digestion of lipids and food waste

A thermophilic anaerobic co-digestion system treating lipids and food waste was demonstrated by a long-term operation (over 600 days) with different lipid/TS ratios (from 10 % to 80 %). The lipids degradation efficiency achieved 90 % in the system when the lipid/TS ratio was less than 70 %. Addition of lipids significantly enhanced methane production, as the lipid/TS ratio increased from 10% to 70 %, the biogas production rate increased from 2.36 g/L/d to 3.42 g/L/d with 59.7 % to 67.7 % of methane. From the view of system stability, the increase of lipid/TS ratio reduced the alkalinity of the system and eventually caused the system collapse. In order to avoid losses due to overload, the results suggested that the ratio of total ammonia nitrogen to alklinity-6.5 could be used as a monitoring indicator. And the system could maintain efficient operation when the indicator was less than 0.6.

Evaluation of the Effect of Probiotic Yogurt Consumption on Salivary pH, Buffering Capacity and Calcium Level in 6-12-year-old Children: An In Vivo Study

Introduction

Dental caries is a preventable disease that can be prevented by suppressing any one of the factors of the Keyes triad.

Aim and objective

To investigate the effect of probiotic yogurt on salivary pH, calcium level, and buffering capacity.

Materials and methods

A total of 60 children were randomly selected and were divided into 2 groups. The test group consumed 200 mL of probiotic yogurt and the control group consumed 200 mL of regular curd everyday for 30 days. A base-line nonstimulated salivary sample (2 mL) was collected. The salivary pH, buffering capacity, and calcium level was assessed at baseline, after 15 and 30 days. The data were statistically analyzed.

Result

The mean pH levels of the probiotic group were 7.03 and salivary buffering capacity was found to be 2.000. Salivary calcium levels increased with the use of probiotic yogurt at the end of 30 days (mean of 4.79) compared to the control group.

Conclusion

Consumption of probiotic yogurt for a short period of time can prevent dental caries by increasing salivary calcium level.

How to cite this article

Malavalli PL, Shetty SB, Thimmaiah C, et al. Evaluation of the Effect of Probiotic Yogurt Consumption on Salivary pH, Buffering Capacity and Calcium Level in 6-12-year-old Children: An In Vivo Study. Int J Clin Pediatr Dent 2022;15(2):194-198.

A Comparative Study of Salivary Flow Rate, pH, Buffer Capacity, Total Antioxidant Capacity, and Ferritin Levels in Children with Beta Thalassemia Major and Healthy Children

Introduction

Thalassemia is a genetically diverse group of disease which occurs due to an imbalance in the production of the alpha and beta chains with ensuring chronic hemolysis, ineffective erythropoiesis, and iron overload.

Aim and objective

The main aim of the study is to compare the salivary flow rate, pH, buffer capacity, total antioxidant capacity, and ferritin levels in children with beta thalassemia major and healthy children.

Materials and methods

The present study includes 40 children consisting of 20 beta thalassemia major and 20 healthy children. Unstimulated saliva was collected by the spitting method. The salivary flow rate, pH, buffer capacity, total antioxidant capacity, and ferritin levels were evaluated.

Results

Salivary ferritin levels were found to be higher in children with beta thalassemia major.

Conclusion

Iron overload is also known as hemochromatosis which is one of the complications of thalassemia.

How to cite this article

Rao GV, Preethi V, Daneswari V, et al. A Comparative Study of Salivary Flow Rate, pH, Buffer Capacity, Total Antioxidant Capacity, and Ferritin Levels in Children with Beta Thalassemia Major and Healthy Children. Int J Clin Pediatr Dent 2021;14(3):342-348.

Assessing the impacts of differential depositional settings and/or anthropogenic perturbations on sulfur and iron diagenesis in sediments of the Bohai Sea and North Yellow Sea

Natural processes and human activities exert important impacts on elemental cycling in coastal sediments, which has not been well documented. Sediments in the Bohai Sea and North Yellow Sea were investigated to assess the impacts of the Yellow River inputs and/or anthropogenic perturbations on diagenesis of iron and sulfur. Labile iron (0.5 M HCl-extractable iron) in the sediments is low due to iron-poor nature of source materials. Dynamic regimes and low availability of labile organic carbon (OC) result in relatively low sulfide contents in deltaic sediments. However, low but continuous supply of labile OC exported from an anthropogenically impacted bay could substantially elevate sulfide burial in sediments near the bay. Neither offshore oil exploitations nor frequent algal blooms in the seas have detectable influences on iron and sulfur diagenesis in the sediments. The sediments are capable of quickly consuming porewater sulfide by reaction with reactive iron under the current conditions.

A water-soluble glass-based temporary restorative resin inhibited bacteria-induced pH reductions at the bacteria-material interface

This study aimed to evaluate the inhibitory effects of a water-soluble glass based temporary restorative resin (WSG-TRR) on bacteriainduced pH reductions at the bacteria-material interface. Each material (WSG-TRR, glass-ionomer cement, resin composite and conventional temporary restorative resin) was fixed to the bottom of the well of the experimental apparatus. The well was filled with pelleted cells of Streptococcus mutans, and the pH at the bacteria-material interface was monitored using a miniature pH electrode. The concentration of ions released from WSG-TRR and the effect of fluoride and zinc ions on bacteria-induced pH reduction was evaluated. The buffering capacities of WSG-TRR and WSG were also evaluated. At 90 min after the glucose addition, WSG-TRR exhibited the highest pH (5.29±0.12). Fluoride ion was detected at the interface between bacteria and WSG-TRR. Moreover, WSG were found to confer high buffering capacity. A WSG-TRR reduced bacteria-induced pH reductions at the bacteria-material interface.

Alleviation of ammonia inhibition via nano-bubble water supplementation during anaerobic digestion of ammonia-rich swine manure: Buffering capacity promotion and methane production enhancement

Anaerobic digestion (AD) of ammonia-rich swine manure (SM) with nano-bubble water (NBW) supplementation was studied in this work with the expectation of ammonia inhibition alleviation, buffering capacity promotion, and methane production enhancement. Results indicated that cumulative methane yield was elevated by 12.3-38.7% in NBW groups. Besides, the reduced methane production rate and elongated lag phase under ammonia inhibition were increased and shortened by NBW supplementation, respectively. The rapid increase of total alkalinity (TA) and partial alkalinity (PA) could be observed with NBW supplementation, as well as the rapid decline of VFA/TA, thus improved buffering capacity and alleviated ammonia inhibition. Moreover, higher level of extracellular hydrolases and coenzyme F₄₂₀ could be detected in NBW groups. In conclusion, NBW with higher mobility and zeta potential (absolute value) could be a promising strategy for the alleviation of ammonia suppression during the AD of SM.

Correlation between microbial host factors and caries among older adults

Background

There is little knowledge about factors which may affect oral health among older adults. The objective of this study was to determine the relationship between Streptococcus mutans (MS) and Lactobacilli (LB) counts and caries among older adults.

Methods

In this community-based observation study, 141 participants aged 60 years and above were recruited from the west district of Singapore. Alongside the clinical examination, saliva samples were collected to determine Streptococcus mutans (MS) and Lactobacilli (LB) counts, as well as to record salivary flow rate and buffering capacity of saliva.

Results

Of the 141 participants, 63.8% were female and 94.3% were of Chinese ethnicity. The mean DMFT was 11.08 (s.d. 8.27). 9.9% of participants had at least one decayed tooth, 52.5% had minimum one missing tooth and 86.5% had at least one filled tooth. 67.4% had MS counts of ≥ 10⁵ while LB counts were ≥ 10⁵ for 48.2%. 83.7% had normal salivary flow or hypersalivation (> = 1 mL/min), the buffering capacity of the saliva was alkaline in 61% of the participants. Multivariate analysis showed that participants who had high MS counts were less likely to have a DMFT < 12 [OR (95% CI), 0.29 (0.11–0.77)] whereas participants who had high LB counts were less likely to have a DMFT ≤ 14 [OR (95% CI), 0.45 (0.20–1.002)].

Conclusion

Our study showed a positive correlation between MS and LB counts and caries experience in older adults. The mean DMFT was on the low side in our sample despite having a relatively high MS count. This suggests that there are many other factors which vary according to host environment, physiological and biological conditions that may affect MS and LB counts in the oral cavity.

Clinical relevance

Our study supports the knowledge that the aetiology of dental caries among older adults is a complex process and it would be wrong to consider caries as a same problem with the same solution for all age groups.

Efficacy of gel-based artificial saliva on Candida colonization and saliva properties in xerostomic post-radiotherapy head and neck cancer patients: a randomized controlled trial

Objective

To evaluate the efficacy of an edible artificial saliva gel, oral moisturizing jelly (OMJ), and a topical commercial gel (GC dry mouth gel) on Candida colonization and saliva properties.

Materials and methods

This study was a secondary analysis of a single-blinded randomized controlled trial conducted in xerostomic post-radiotherapy head and neck cancer patients. Candida colonization, stimulated salivary flow rate (SSFR), saliva pH, and buffering capacity (BC) were measured at 0, 1, and 2 months after each intervention. Candida colonization was quantified by colony counts and species identified by Candida Chromagar, polymerase chain reaction, and API 20C AUX system. Statistical significance level was 0.05.

Results

A total of 56 participants in OMJ (N = 30) and GC (N = 26) groups completed the study. OMJ significantly increased saliva pH (p = 0.042) and BC (p = 0.013) after 1-month use, while GC only improved saliva pH (p = 0.027). Both interventions tended to increase SSFR but only GC had a significant increase at 2 months (p = 0.015). GC and OMJ significantly decreased the number of Candida species at 1 and 2 months, respectively. Both groups tended to reduce Candida counts but not significant.

Conclusions

Both OMJ and GC saliva gels could improve saliva pH and decrease the number of Candida species. OMJ is superior to GC in its buffering capacity, while GC may better improve salivary flow rate. Long-term and large-scale study is warranted to test the efficacy of artificial saliva in oral health improvement.

Clinical relevance

OMJ and GC gel could decrease the number of Candida species and improve saliva properties in post-radiation xerostomic patients.

Trial registration number

Clinicaltrials.gov NCT03035825. Date of registration: 25th January 2017.

Enhancement of bio-hydrogen yield and pH stability in photo fermentation process using dark fermentation effluent as succedaneum

The photo fermentation hydrogen yield from dark fermentation effluents (DFEs) can be promoted by adding corn straw enzymatic hydrolysate adjusts the nutritional composition of DFEs. As compared with the control group (without enzymatic hydrolysate addition), the effect of adding enzymatic hydrolysate make H₂ yield increase from 312.54 to 1287.06 mL H₂/g TOC, and maximum hydrogen production rate increase 2.14 to 10.23 mL/h. On the other hand, buffer reagents remained in DFEs make which can replace part sodium citrate buffer to maintain pH stability in synchronized saccharification and photosynthetic fermentation process with corn straw as substrate, the best result was observed at the ration of 1:2 (33 mL DFEs, 67 mL sodium citrate buffer) with the hydrogen yield of 436.30 ± 10 mL, and which can cut down the GHG in the life cycle of hydrogen production.

Growth parameters of Liberibacter crescens suggest ammonium and phosphate as essential molecules in the Liberibacter-plant host interface

Background

Liberibacter crescens is the closest cultured relative of four important uncultured crop pathogens. Candidatus. L. asiaticus, L. americanus, L. africanus cause citrus greening disease, while Ca. L. solanacearum causes potato Zebra chip disease. None of the pathogens grows in axenic culture. L. crescens grows in three media: a BM-7, a serum-free Hi® Grace’s Insect Medium (Hi-GI), and a chemically-defined medium called M15. To date, no optimal growth parameters of the model species L. crescens have been reported. Studying the main growth parameters of L. crescens in axenic culture will give us insights into the lifestyle of the Ca. Liberibacter pathogens.

Results

The evaluation of the growth parameters—pH, aeration, temperature, and buffering capacity—reflects the optimal living conditions of L. crescens. These variables revealed that L. crescens is an aerobic, neutrophilic bacterium, that grows optimally in broth in a pH range of 5.8 to 6.8, in a fully oxygenated environment (250 rpm), at 28 °C, and with monosodium phosphate (10 mM or 11.69 mM) as the preferred buffer for growth. The increase of pH in the external media likely results from the deamination activity within the cell, with the concomitant over-production of ammonium in the external medium.

Conclusion

L. crescens and the Ca. Liberibacter pathogens are metabolically similar and grow in similar environments—the phloem and the gut of their insect vectors. The evaluation of the growth parameters of L. crescens reveals the lifestyle of Liberibacter, elucidating ammonium and phosphate as essential molecules for colonization within the hosts. Ammonium is the main driver of pH modulation by active deamination of amino acids in the L. crescens amino acid rich media. In plants, excess ammonium induces ionic imbalances, oxidative stress, and pH disturbances across cell membranes, causing stunted root and shoot growth and chlorosis—the common symptoms of HLB-disease. Phosphate, which is also present in Ca. L. asiaticus hosts, is the preferred buffer for the growth of L. crescens. The interplay between ammonium, sucrose, potassium (K⁺), phosphate, nitrate (NO₃⁻), light and other photosynthates might lead to develop better strategies for disease management.

Variation of green liquor dregs from different pulp and paper mills for use in mine waste remediation

The geotechnical, chemical, and mineralogical properties of green liquor dregs (GLDs) generated as byproducts from five paper mills were investigated to assess their buffering and heavy metal immobilization capacities and their roles as water and oxygen barriers. One type of GLD was further studied to test the effects of the retrieval process and the storage, drying, and hydration of GLD. The high water retention capacity of the GLDs is valuable for limiting O₂ diffusion. Laboratory results showed that the GLDs had hydraulic conductivities of 3.7 × 10^-9-4.6 × 10^-8 m/s and varied regularly in plasticity. The chemical and mineralogical compositions of the GLDs varied greatly, reflecting the raw material used to produce paper and the process used to retrieve GLDs. Although they had high total heavy metal contents, none of the leached elements from the GLDs (L/S 10 cm³/kg) exceeded the European Union's limits for landfills of non-hazardous waste. The GLDs exhibited high buffering capacities. In a supplementary test, the buffering capacities varied (0.0041-0.0114 M H⁺/g GLD) over 72 d after acid was added to the GLD. Changing the filtration process did not greatly affect the GLDs' properties but mainly affected the hydraulic conductivity, total heavy metal contents and sulfur content. Analyzing the storage of GLDs is necessary in the mining industry because remediation measures require large amounts of material over short periods. The buffering capacity of the dried GLD decreased slightly. The effect of dewatering caused by the mixing of 2% Na-lignosulfate with GLD (w/w) was low.

Reconstructed chitosan with alkylamine for enhanced gene delivery by promoting endosomal escape

Poor buffering capacity of chitosan (CS) results in insufficient intracellular gene release which poses the major barrier in gene delivery. Herein, we reconstructed pristine CS with propylamine (PA), (diethylamino) propylamine (DEAPA), and N, N-dimethyl- dipropylenetriamine (DMAMAPA) to obtain a series of alkylamine-chitosan (AA-CS). The introduction of multiple amino groups with rational ratios functionally enhance the buffering capacity of AA-CS, among which DMAPAPA-CS showed buffering capacity of 1.58 times that of chitosan. The reconstructed AA-CS functionally enhance the ability of gene binding and endosomal escape. It was observed that the DMAPAPA-CS/pDNA complexes exhibit a notable gene delivery efficiency, which promotes the functionalization of loaded pDNA. Importantly, the in vivo delivery assay reveals that the deep penetration issue can be resolved using DMAPAPA-CS gene delivery vector. Finally, the DMAPAPA-CS is applied to deliver the therapeutic p53 gene in A549 bearing mice, showing efficient therapeutic potential for cancer.

Comparison of Punica granatum, Terminalia chebula, and Vitis vinifera Seed Extracts used as Mouthrinse on Salivary Streptococcus mutans Levels in Children

AIM

The present study was conducted to compare the efficacy of all Punica granatum, Terminalia chebula, and Vitis vinifera on salivary Streptococcus mutans levels in children and also to evaluate their substantivity at an interval of 15 days that is at day 1, days 16, and 31.

MATERIALS AND METHODS

This study was designed for a randomized clinical double-blinded study where 80 children of 8-15 years of age were living in a residential premise. Subjects were randomly divided into 4 groups of 20 each to whom mouthrinses were given. The criteria for assessing the efficacy was done by collecting the saliva sample for pH, buffering capacity, plaque index, and Streptococcus mutans microbiologic assay. These values were assessed at the baseline, days 16, and 31. Children were asked to discontinue mouthrinse from days 16 to 31. The supervisor was trained to administer the mouthrinses properly.

RESULTS

The data were coded and analysis was done using the SPSS version 20. The level of significance was set at p < 0.05. The pH and buffering capacity showed that values were almost the same among all four groups at various time intervals which showed statistically nonsignificant results. Punica granatum showed a maximum reduction in S. mutans count followed by T. chebula and V. vinifera, although they were statistically nonsignificant. The Vitis vinifera group had successfully reduced more plaque score at day 16 (0.04) followed by T. chebula (0.09) and P. granatum (0.12).

CONCLUSION

This in vivo study implied that V. vinifera had shown the lowest plaque reduction owing to its antioxidant and phytochemical properties. And P. granatum showed the maximum substantivity.

CLINICAL SIGNIFICANCE

Mouthrinses helped in reducing plaque deposition, caries activity, and helped in oral hygiene maintenance. Hereby, we can conclude that nutraceutical mouthrinses are safe in children and produced superior results than the chemical mouthrinses.

Changes in essential salivary parameters in patients undergoing fixed orthodontic treatment: A longitudinal study

Objective

Orthodontic treatment using fixed appliances is known to alter the oral environment and encourage plaque retention around orthodontic brackets and bands, resulting in enamel demineralization and gingival inflammation. This study aimed to evaluate the changes in essential salivary parameters in patients undergoing fixed orthodontic treatment.

Materials and Methods

Saliva samples were collected from 60 patients before and 2 months after commencing fixed orthodontic treatment. The salivary flow rate, pH, buffering capacity, and levels of amylase, total protein, and glucose were determined. Parametric and nonparametric tests for paired samples were used for comparing the mean differences before and after commencing treatment.

Results

Significant reductions in the salivary flow rate, pH, and buffering capacity were noted 2 months after commencing treatment (P < 0.05). Total protein concentrations and calcium levels decreased significantly and amylase and glucose levels increased after commencing treatment (P < 0.05). Significant correlations were observed between salivary total protein concentrations and buffering capacity as well as calcium levels (P < 0.05).

Conclusion

These findings indicate that the biochemical properties of saliva are altered after introducing fixed orthodontic appliances into the oral cavity, thereby promoting plaque retention and increasing the susceptibility to tooth demineralization and gingival inflammation.

Sulfur, iron, and phosphorus geochemistry in an intertidal mudflat impacted by shellfish aquaculture

Dissolved sulfide, iron (Fe), and phosphorus (P) in a mudflat (Jiaozhou Bay, China) impacted by shellfish aquaculture were measured in situ by the diffusive gradients in thin films (DGT) technique. A combination of porewater and solid-phase chemistry was used to characterize the interplays of Fe and S, and their control on P mobilization. Below the subsurface layer, two times higher fluxes (F_DGT) of dissolved Fe²⁺ from porewater to the DGT device than those of dissolved sulfide indicate that dissimilatory iron reduction (DIR) dominates over sulfate reduction (SR). Spatial coupling of dissolved Fe²⁺ and P points to P release driven mainly by reductive dissolution of Fe. Much higher F_DGT values of dissolved Fe²⁺ relative to dissolved P imply that oxidative regeneration of Fe oxides at the sediment-water interfaces (SWIs) of the transitional mudflat serves as an effective "iron curtain" of upward diffusing P. In the mudflat sediments of DIR prevalence, the accumulation of total reduced inorganic sulfur (TRIS) is dampened, which can largely ascribed to enhanced oxidative loss of sulfide and/or limited availability of degradable organic carbon in the dynamic regimes. Low dissolved sulfide concentrations in the sediments leave the majority of reactive Fe unsulfidized and thus abundantly available to buffer newly produced sulfide.

Effects of different types of biochar on the anaerobic digestion of chicken manure

This study investigated the impact of different types of biochar on the anaerobic digestion (AD) of chicken manure. Wheat straw, discarded fruitwood, and air-dried chicken manure were pyrolysed at 350, 450, and 550 °C to generate biochar. A lab-scale batch anaerobic digestion experiment was conducted at 35 ± 1 °C. Substantial improvements in methane production were observed for all nine types of biochar. With the production of 294 mL CH₄/g VS_added, fruitwood char pyrolysed at 550 °C increased the methane yield by 69% from the control. Characteristic analysis indicated that fruitwood char pyrolysed at 550 °C exhibited the largest specific surface area and highest total ammonia nitrogen reduction capacity. The buffering capacity of the AD system was improved by the biochar through accelerating the transformation of macromolecular substances to dissolved substrates and reducing the contents of soluble salts, total ammonia nitrogen, and free ammonia.

Salivary Flow Rate, pH, Buffering Capacity, Total Protein, Oxidative Stress and Antioxidant Capacity in Children with and without Dental Caries

OBJECTIVES

To measure and compare the levels of salivary flow rate, pH, buffering capacity, total protein, malondialdehyde (MDA) and total antioxidant capacity (TAC) between caries active and caries free children and to study the correlation between the DMFS/dfs score and above salivary parameters in caries active children.

STUDY DESIGN

50 caries active (DMFS/dfs ≥ 5) and 50 caries free (DMFS/dfs = 0) children aged between 6 to 12 years were included in the study. From all the children, unstimulated, mid-morning saliva samples were collected and salivary flow rate was calculated. Salivary pH, buffering capacity, total protein, MDA and TAC were measured.

RESULTS

The mean levels of salivary flow rate, pH, buffering capacity were significantly decreased (p < 0.05) and total protein, MDA and TAC were significantly increased (p < 0.05) in caries active children when compared to caries free controls. There was a proportionate decrease (p < 0.05) in salivary flow rate, pH and buffering capacity and proportionate increase (p > 0.05) in salivary total protein, MDA and TAC as DMFS/dfs score increased in caries active children.

CONCLUSIONS

Significant alteration in the levels of salivary flow rate, pH, total proteins, MDA and TAC and their correlation with DMFS/dfs score in caries active children suggest, the levels of these physico-chemical properties of saliva can act as strong indicators of caries status in children.

Hydrological and hydrochemical behavior of a riparian zone in a high-order flatland stream

Hydrological and hydrochemical processes occurring within riparian zones in temperate mid-latitudes flatland areas have significant implications for water management by controlling nutrient transfer between the watershed and the stream system. The riparian zone in a high-order flatland stream located within a 7063-km² agricultural watershed in Argentina was investigated to study its hydrological connectivity to upland zones, interactions with the stream, and their implications for groundwater hydrochemistry. The analysis was based on 9-year-long time series of groundwater/stream water levels collected along a 220-m-long transect comprising six piezometers, a river stage sensor, and hydrochemical information from 37 groundwater/stream water sampling campaigns. Samples were analyzed for electrical conductivity (EC), Cl^-, SO₄⁺², (Ca⁺² + Mg⁺²), pH, and redox potential (ORP). Data were interpreted using descriptive statistics, statistical tests, groundwater flux calculations, and identification of hydrological patterns and associated hydrochemical responses. The system was hydrologically controlled by shallow groundwater. Three representative landscape hydrological patterns were identified: disconnected, incipient-weakly connected, and fully connected. Groundwater hydrochemistry was closely linked to hydrological connectivity, which played an important role in the mobilization and fluxes of solutes. Overall, groundwater EC, Cl^-, SO₄⁺², and (Ca⁺² + Mg⁺²) concentrations decreased from upland to lowland. For full connectivity, Cl^- concentrations reduced 33%, while SO₄⁺² reduced 42%, demonstrating the system's buffering capacity. This investigation constitutes the first attempt to formulate the riparian zone functioning in this agricultural region and has contributed to the understanding on the complex interactions between hydrologic regimes of large flatland-high-order streams and shallow groundwater systems in fine-texture sediments.

Use of metal chlorides during waste wheat straw autohydrolysis to overcome the self-buffering effect

High ash content of waste wheat straw (WWS) is resistant to biorefinery autohydrolysis pretreatment due to its self-buffering effects. In this work, minor addition FeCl₃ and AlCl₃ were applied to overcome the self-buffering effects of WWS by cationic occupation of the negatively charged sites present on particulate ash's surface. The results showed that with the increasing concentrations (0-20 mM) of AlCl₃ and FeCl₃, the enzymatic efficiencies of autohydrolyzed WWS were enhanced from 49.7% to 62.1% and 66.6%, respectively. Acid buffer and cation exchange capacity of pretreated WWS were decreased by adding metal chlorides and the reducing results were mainly attributed to cation exchange. Meanwhile, a maximum monosaccharide production (185.3 mg/g-WWS) was achieved with 62.0 mg/g-WWS xylooligosaccharide by using 20 mM FeCl₃ during WWS autohydrolysis. The results demonstrated that the implications of FeCl₃ and AlCl₃ in WWS autohydrolysis were an effective strategy to enhance autohydrolysis efficiency by overcoming self-buffering effects.

Impacts of different biochar types on hydrogen production promotion during fermentative co-digestion of food wastes and dewatered sewage sludge

Pyrolysis and anaerobic digestion are two important strategies for waste management that may be combined for clean energy production. This article investigates the effects of 12 types of biochars derived from four feedstocks at three pyrolysis temperatures on H₂ production via fermentative co-digestion of food wastes and dewatered sewage sludge. The results show that feedstock type and pyrolysis temperature significantly influence biochar properties such as pH, specific surface area and ash contents. Despite the wide range of BET specific surface areas (1.2-511.3 m²/g) and ash contents (5.3-73.7(wt%)) of biochars produced, most biochars promoted the VFAs production process and altered the fermentative type from that of acetate type to butyrate type, which seemed to have a higher efficiency for H₂ production. Moreover, fitting of the results to the modified Gompertz model shows that biochar addition shortens the lag time by circa 18-62% and increases the maximum H₂ production rate by circa 18-110%. Furthermore, the biochar derived at higher pyrolysis temperatures enhances H₂ production dramatically over those derived at low temperatures. Principal components analysis demonstrated that the pH buffering capacity of biochar was critical to the promotion of fermentative H₂ production by mitigating the pH decrease caused by VFAs accumulation. Consequently, a sustainable integrated waste management strategy combining pyrolysis and anaerobic digestion is proposed for the efficient treatment of various bio-wastes.

Potentials of using mixed culture bacteria incorporated with sodium bicarbonate for hydrogen production from water hyacinth

The aim of this study is to assess the potentials of using mixed culture bacteria incorporated with different concentrations of NaHCO₃ for hydrogen production from water hyacinth (WH). The lowest hydrogen yield (HY) of 30.4 ± 1.9 mL/g_TVS, H₂ content (HC) of 19.5 ± 1.5% and hydrogenase enzyme (HE) activity of 0.06 ± 0.01 mgM.B_reduced/min were registered for the cultures without supplementation of NaHCO₃. The HY, HC, and HE activity were maximized at levels of 69.2 ± 4.3 mL/g_TVS, 58.4 ± 3.6% and 0.18 ± 0.01 mgM.B_reduced/min. respectively for the anaerobes supplied with 3.0 g NaHCO₃/L. Furthermore, cellulose, hemicellulose, and lignin destruction efficiencies were 37.2 ± 2.3, 30.0 ± 1.9 and 20.9 ± 1.3% respectively due to the increase of cellulase and xylanase activities up to 2.73 ± 0.17 and 1.87 ± 0.12 U/mL, respectively. Moreover, the abundance of Firmicutes was substantially increased and accounted for 71% of the total OTU's. Microbes belonging to the order Clostridiales and OPB54 were particularly enriched in the medium supplemented with NaHCO₃.

Reduced non-bicarbonate skeletal muscle buffering capacity in mice with the mini-muscle phenotype

Muscle pH decreases during exercise, which may impair function. Endurance training typically reduces muscle buffering capacity as a result of changes in fiber-type composition, but existing comparisons of species that vary in activity level are ambiguous. We hypothesized that high-runner (HR) lines of mice from an experiment that breeds mice for voluntary wheel running would have altered muscle buffering capacity as compared with their non-selected control counterparts. We also expected that 6 days of wheel access, as used in the selection protocol, would reduce buffering capacity, especially for HR mice. Finally, we expected a subset of HR mice with the 'mini-muscle' phenotype to have relatively low buffering capacity as a result of fewer type IIb fibers. We tested non-bicarbonate buffering capacity of thigh muscles. Only HR mice expressing the mini-muscle phenotype had significantly reduced buffering capacity, females had lower buffering capacity than males, and wheel access had no significant effect.

Qualitative and quantitative salivary changes and subjective oral dryness among patients with thyroid dysfunction

Context

There is a paucity of literature regarding the effects of thyroid disorders on the oral cavity by influencing the salivary gland function.

Aims

This study aims to understand the qualitative and quantitative changes that thyroid disorder can cause in the salivary function.

Settings and Design:

After obtaining ethical clearance, 46 consecutive newly diagnosed thyroid dysfunction patients were enrolled in this cross-sectional study, along with 45 age-and sex-matched controls.

Subjects and Methods:

Unstimulated and stimulated salivary flow rates, pH, and buffering capacity of the whole saliva were studied in addition to subjective oral dryness in the study participants.

Statistical Analysis Used:

The independent t-test was employed to compare the means between the two groups and Pearson's Chi-square test was used to assess the goodness of fit.

Results

The findings showed that females are more affected with thyroid disorders and that hypothyroidism is more commonly reported than hyperthyroidism. A significant reduction in the salivary flow rates and buffering capacity was observed among the affected group compared to the controls, whereas the salivary pH did not show significant differences between genders and also between the case and control groups. A feeling of subjective oral dryness was perceived by many affected patients.

Conclusions

The study was able to establish an association between thyroid dysfunction and salivary gland function. We hope that this study leads to more high-impact research in this field as salivary diagnostics is gaining more popularity with every passing day.

Investigating on the fermentation behavior of six lactic acid bacteria strains in barley malt wort reveals limitation in key amino acids and buffer capacity

Understanding lactic acid bacteria (LAB) fermentation behavior in malt wort is a milestone towards flavor improvement of lactic acid fermented malt beverages. Therefore, this study aims to outline deficiencies that may exist in malt wort fermentation. First, based on six LAB strains, cell viability and vitality were evaluated. Second, sugars, organic acids, amino acids, pH value and buffering capacity (BC) were monitored. Finally, the implication of key amino acids, fructose and wort BC on LAB growth was determined. Short growth phase coupled with prompt cell death and a decrease in metabolic activity was observed. Low wort BC caused rapid pH drop with lactic acid accumulation, which conversely increased the BC leading to less pH change at late-stage fermentation. Lactic acid content (≤3.9 g/L) was higher than the reported inhibitory concentration (1.8 g/L). Furthermore, sugars were still available but fructose and key amino acids lysine, arginine and glutamic acid were considerably exhausted (≤98%). Wort supplementations improved cell growth and viability leading to conclude that key amino acid depletion coupled with low BC limits LAB growth in malt wort. Then, a further increase in organic acid reduces LAB viability. This knowledge opens doors for LAB fermentation process optimization in malt wort.

Changes in bacteria composition and efficiency of constructed wetlands under sustained overloads: A modeling experiment

The average organic and hydraulic loads that Constructed Wetlands (CWs) receive are key parameters for their adequate long-term functioning. However, over their lifespan they will inevitably be subject to either episodic or sustained overloadings. Despite that the consequences of sustained overloading are well known (e.g., clogging), the threshold of overloads that these systems can tolerate is difficult to determine. Moreover, the mechanisms that might sustain the buffering capacity (i.e., the reduction of peaks in nutrient load) during overloads are not well understood. The aim of this work is to evaluate the effect of sudden but sustained organic and hydraulic overloads on the general functioning of CWs. To that end, the mathematical model BIO_PORE was used to simulate five different scenarios, based on the features and operation conditions of a pilot CW system: a control simulation representing the average loads; 2 simulations representing +10% and +30% sustained organic overloads; one simulation representing a sustained +30% hydraulic overload; and one simulation with sustained organic and hydraulic overloads of +15% each. Different model outputs (e.g., total bacterial biomass and its spatial distribution, effluent concentrations) were compared among different simulations to evaluate the effects of such operation changes. Results reveal that overloads determine a temporary decrease in removal efficiency before microbial biomass adapts to the new conditions and COD removal efficiency is recovered. Increasing organic overloads cause stronger temporary decreases in COD removal efficiency compared to increasing hydraulic loads. The pace at which clogging develops increases by 10% for each 10% increase on the organic load.

Effects of β-Alanine Supplementation on Carnosine Elevation and Physiological Performance

β-Alanine is one of the more popular sport supplements used by strength/power athletes today. The popularity of β-alanine stems from its ability to enhance intracellular muscle-buffering capacity thereby delaying fatigue during high-intensity exercise by increasing muscle carnosine content. Recent evidence also suggests that elevated carnosine levels may enhance cognitive performance and increase resiliency to stress. These benefits are thought to result from carnosine's potential role as an antioxidant. This review will discuss these new findings including recent investigations examining β-alanine supplementation and increased resiliency to posttraumatic stress and mild traumatic brain injury. This review will focus on the physiology of carnosine, the effect of β-alanine ingestion on carnosine elevations, and the potential ergogenic benefits it has for competitive and tactical athletes.

Effects of dietary yeast inclusion and acute stress on post-prandial whole blood profiles of dorsal aorta-cannulated rainbow trout

Yeast is a potential alternative to fish meal in diets for farmed fish, yet replacing more than 50 % of fish meal results in reduced fish growth. In a 4-week experiment, 15 rainbow trout (Oncorhynchus mykiss) were cannulated and fed three diets each week: 30 % fish meal as a control (FM); 60 % replacement of fish meal protein, on a digestible basis, with Saccharomyces cerevisiae (SC); and 60 % replacement with Wickerhamomyces anomalus and S. cerevisiae mix (WA). Blood was collected at 0, 3, 6, 12 and 24 h after feeding. In the final week, fish were exposed to a 1-min netting stressor to evaluate possible diet-stress interactions. Significant increases in pH, TCO₂, HCO₃ and base excess were found after fish were fed the SC and WA diets compared with FM, which elevated blood alkaline tides. Yeast ingredients had lower buffering capacity and ash content than fish meal, which explained the increase in alkaline tides. In addition, fish fed the WA diet had significantly reduced erythrocyte area and fish fed SC and WA diets had increased mean corpuscular haemoglobin levels, indicating haemolytic anaemia. Higher levels of nucleic acid in yeast-based diets and potentially higher production of reactive oxygen species were suspected of damaging haemoglobin, which require replacement by smaller immature erythrocytes. Acute stress caused the expected rise in cortisol and glucose levels, but no interaction with diet was found. These results show that replacing 60 % of fish meal protein with yeasts can induce haemolytic anaemia in rainbow trout, which may limit yeast inclusion in diets for farmed fish.

Multispecies reactive transport modelling of electrokinetic remediation of harbour sediments

We implemented a numerical model to simulate transport of multiple species and geochemical reactions occurring during electrokinetic remediation of metal-contaminated porous media. The main phenomena described by the model were: (1) species transport by diffusion, electromigration and electroosmosis, (2) pH-dependent buffering of H⁺, (3) adsorption of metals onto particle surfaces, (4) aqueous speciation, (5) formation and dissolution of solid precipitates. The model was applied to simulate the electrokinetic extraction of heavy metals (Pb, Zn and Ni) from marine harbour sediments, characterized by a heterogeneous solid matrix, high buffering capacity and aged pollution. A good agreement was found between simulations of pH, electroosmotic flow and experimental results. The predicted residual metal concentrations in the sediment were also close to experimental profiles for all of the investigated metals. Some removal overestimation was observed in the regions close to the anode, possibly due to the significant metal content bound to residual fraction.

Correlation between Salivary Glucose and Blood Glucose and the Implications of Salivary Factors on the Oral Health Status in Type 2 Diabetes Mellitus Patients

AIMS AND OBJECTIVES

The purpose of this study was to estimate and assess any correlation between random capillary blood glucose (RCBG) and unstimulated whole salivary glucose (UWSG), as well as to estimate various salivary parameters, such as flow rate, pH, buffering capacity, and the influence of these factors on the oral health status in type 2 diabetes mellitus (DM).

MATERIALS AND METHODS

Sixty individuals suffering from type 2 DM and 40 healthy individuals in the age group of 30-60 years were included in the study. RCBG was estimated using glucometer and UWSG was estimated using photocolorimeter. Salivary parameters such as flow rate, pH, and buffering capacity were assessed using GC® Saliva kit. Oral health status was recorded using the Russell's periodontal index (RPI) and the Decayed Missing Filled Teeth (DMFT) index. The Statistical Package for the Social Sciences version 16 was used for statistical analysis.

RESULTS

Type 2 diabetics had higher mean values for RCBG levels and UWSG. Type 2 diabetics had low mean salivary flow rate, pH, and buffering capacity. Type 2 diabetics had higher mean values for RPI.

CONCLUSION

Among the salivary factors studied, salivary glucose significantly influenced the periodontal status in Type 2 diabetics.

Comparison of Gingival Health and Salivary Parameters among Autistic and Non-Autistic School Children in Riyadh

INTRODUCTION

Autism is a neuro-developmental disorder which is manifested as impairment of social interaction, communication and a repetitive behaviour. Autism can obscure dental treatment for the affected patients; furthermore, children with autism commonly have destructive oral habits.

AIM

The aims of this study were to evaluate the Modified Gingival Index (MGI), Plaque Index (PI), salivary pH and buffering capacity of the saliva among autistic children compared to normal children in Riyadh City that may provide baseline data to enable comparison and future planning of dental services for autistic children.

MATERIALS AND METHODS

A total of 50 children diagnosed with autism (mean age 8.5 years) were selected from Azzam Autism School, Riyadh City. The control group consisted of 50 non-autistic school children (mean age 8.7 years), gender matched, selected from Outpatient Clinic, Riyadh Colleges of Dentistry and Pharmacy. MGI, PI, salivary pH and salivary buffer capacity tests were done for all participants. The buffering capacity of the stimulated saliva was grouped under 'very low', 'low' and 'normal'. Pearson's Chi square and one way ANOVA were used to find statistical significance if any among the autistic and the normal control group.

RESULTS

The results of the study showed that the mean ± standard deviation of MGI, PI and pH of unstimulated resting saliva for autistic group were 1.82 ± 0.65, 1.92 ± 0.35 and 6.8 ± 0.5 respectively. Normal control group had values 1.35 ± 0.85, 1.44 ± 0.43 and 7 ± 0.4 respectively. A statistically significant difference between both groups for all parameters was found. Salivary buffering capacity was found to be normal for the majority among both groups. However, 60% children among the autistic group presented with normal buffering capacity of the stimulated saliva as compared to 70% among the normal control group. However, this difference was not statistically significant (p = 0.544).

CONCLUSION

Children with autism appear to have higher gingival inflammation, poor oral hygiene and a slightly lower salivary pH as compared to healthy control group. Special oral health programmes regarding treatment and maintenance of good oral health should be taken in consideration for autistic children.

Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity

The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable.

Oral pH in gastroesophageal reflux disease

AIMS AND OBJECTIVES

The aim of this study is to compare surface pH in various parts of the oral cavity between patients with gastroesophageal reflux disease (GERD) and healthy controls.

METHODS

Using a flat pH meter sensor, fixed electrode pen type digital pH meter, oral pH levels were assessed at different mucosal sites among 34 GERD patients and 32 healthy controls. Salivary flow rates and buffering capacity were also assessed in them. A thorough oral examination was performed to screen for any oral and dental changes.

RESULT

A significantly lower pH of 6.65 ± 0.13 (mean ± SD) was found in the GERD group compared to control group 7.23 ± 0.12 (p < 0.05). Least pH was found in the floor of the mouth 6.594 ± 0.17 and highest in the lower labial mucosa among the GERD patients. Salivary flow rate and buffering capacity were low in these patients. Significant changes were noticed in the hard and soft tissues of the oral cavity among the GERD group.

CONCLUSION

Oral mucosal pH is altered in GERD patients and may contribute to effects on the oral cavity.

The potential acidogenicity of liquid breakfasts

OBJECTIVES

To determine the potential acidogenicy of liquid breakfasts.

METHODS

In vitro acid production by Streptococcus mutans was measured in the beverages at a pH of 5.5, as was the fall in pH over 10min. The buffering capacity was determined, as well as the calcium, inorganic phosphate and fluoride concentrations (total and soluble) of the beverages. Bovine milk (UHT) was used for comparison.

RESULTS

The rate of acid production by S. mutans, and pH fall over 10min was greater in liquid breakfasts compared to bovine milk. All beverages except one demonstrated a significantly lower buffering capacity than bovine milk. All beverages contained significantly greater concentrations of soluble calcium than bovine milk, and all except two contained significantly more soluble inorganic phosphate.

CONCLUSIONS

S. mutans was able to generate significantly more acid in the liquid breakfasts than in bovine milk, indicating these drinks may contribute to a cariogenic diet. In general, the liquid breakfasts required significantly less acid than bovine milk to reduce their pH to the approximate critical pH for enamel demineralisation. However, the liquid breakfasts also tended to contain significantly more soluble calcium and inorganic phosphate than bovine milk.

CLINICAL SIGNIFICANCE

The substantial amounts and various types of sugars found within liquid breakfast beverages may result in a significant pH drop in dental plaque following consumption of these products.

Vaginal fluid pH and buffer capacity for predicting false preterm labor in Japanese women

OBJECTIVE

To determine the relationship between preterm labor and delivery, and the pH and buffer capacity of vaginal secretions.

METHODS

Between January 1, 2009 and March 31, 2012, two cohorts of patients at 22-36weeks of pregnancy were enrolled in a prospective cohort study at Nara Medical University Hospital, Japan. Patients experiencing preterm contractions and a control group of patients experiencing normal pregnancies were included. The pH and buffer capacity of vaginal secretions were measured and compared.

RESULTS

Of the 237 patients enrolled, 48 (20.3%) were experiencing symptoms of preterm labor and 189 (79.7%) were included in the control group. The pH was higher (P<0.001) and the buffer capacity was lower (P=0.0135) in the vaginal secretions of the patients experiencing preterm contractions compared with the control group. There was no difference in the pH and buffer capacity of the vaginal secretions of symptomatic patients who would experience preterm delivery and those who would not. Receiver operating characteristic curve analyses demonstrated that vaginal-secretion pH and buffer capacity could differentiate between patients experiencing preterm contractions and those not, but could not differentiate between patients who would experience preterm delivery and those who would not.

CONCLUSION

Vaginal-secretion pH and buffer capacity could be useful in diagnosing preterm labor; further studies are needed to determine potential practical diagnostic criteria.

Salivary pH and Buffering Capacity as Risk Markers for Early Childhood Caries: A Clinical Study

Background: The diagnostic utility of saliva is currently being explored in various branches of dentistry, remarkably in the field of caries research. This study was aimed to determine if assessment of salivary pH and buffering capacity would serve as reliable tools in risk prediction of early childhood caries (ECC).

Materials and methods: Paraffin-stimulated salivary samples were collected from 50 children with ECC (group I) and 50 caries free children (group II). Salivary pH and buffering capacity (by titration with 0.1 N hydrochloric acid) were assessed using a handheld digital pH meter in both groups. The data obtained were subjected to statistical analysis.

Results: Statistically, no significant difference was observed between both the groups for all salivary parameters assessed, except for the buffering capacity level at 150 μl titration of 0.1 N hydrochloric acid (p = 0.73; significant at 1% level).

Conclusion: Salivary pH and buffering capacity may not serve as reliable markers for risk prediction of ECC.

How to cite this article: Jayaraj D, Ganesan S. Salivary pH and Buffering Capacity as Risk Markers for Early Childhood Caries: A Clinical Study. Int J Clin Pediatr Dent 2015;8(3):167-171.

Engineering and characterization of simplified vaginal and seminal fluid simulants

BACKGROUND

Reported vaginal and seminal fluid simulants have complex compositions with multiple preparatory steps that contribute to physical instability. We report the design and characterization of stable and simplified buffers that mimic the salient physical/chemical properties of the physiological fluids.

STUDY DESIGN/METHODS

Human cervicovaginal and seminal fluid samples were collected and buffering capacity was determined. The major buffering species were identified from published compositions of reproductive tract fluids. These values were used to compute the composition of vaginal and seminal fluid simulants. Ionic strength, buffering capacities, pH and osmolalities were then calculated or experimentally determined. Finally, cytotoxicity was evaluated in HEC-1-A cells and 3D reconstructed EpiVaginal™ tissue (VEC-100-FT) using naïve cells/tissue and nonoxynol-9 as controls.

RESULTS

The use of calculated amounts of conjugate acid and base for buffer development resulted in compositions that did not require endpoint pH adjustment and could be formulated as stable 10× concentrates. Furthermore, due to the absence of complex divalent salts, all our proposed simulants were stable at 4 °C for 1 month whereas precipitation and pH and osmolality changes were noted in reported buffers. Experimental determination of buffering capacities yielded similar values for undiluted cervicovaginal fluid (β4.2-5.2=35.6 ± 12.3 mM, N=7) and human seminal fluid (β7-6=37.5 ± 5 mM, N=3). All neat simulants showed significant cytotoxicity in HEC-1-A cells but were well tolerated by organotypic vaginal tissue.

CONCLUSIONS

We report revised and improved compositions of buffers mimicking salient properties of vaginal and seminal fluid necessary for in vitro product evaluation.

IMPLICATIONS

To support research in reproductive health and in particular drug delivery, we have designed and characterized stable new media to mimic these important fluids that can be used in a variety of in vitro studies.

Discontinuous gas-exchange cycle characteristics are differentially affected by hydration state and energy metabolism in gregarious and solitary desert locusts

The termination of discontinuous gas exchange cycles (DGCs) in severely dehydrated insects casts doubt on the generality of the hygric hypothesis, which posits that DGCs evolved as a water conservation mechanism. We followed DGC characteristics in the two density-dependent phases of the desert locust Schistocerca gregaria throughout exposure to an experimental treatment of combined dehydration and starvation stress, and subsequent rehydration. We hypothesized that, under stressful conditions, the more stress-resistant gregarious locusts would maintain DGCs longer than solitary locusts. However, we found no phase-specific variations in body water content, water loss rates (total and respiratory) or timing of stress-induced abolishment of DGCs. Likewise, locusts of both phases re-employed DGCs after ingesting comparable volumes of water when rehydrated. Despite comparable water management performances, the effect of exposure to stressful experimental conditions on DGC characteristics varied significantly between gregarious and solitary locusts. Interburst duration, which is affected by the ability to buffer CO2, was significantly reduced in dehydrated solitary locusts compared with gregarious locusts. Moreover, despite similar rehydration levels, only gregarious locusts recovered their initial CO2 accumulation capacity, indicating that cycle characteristics are affected by factors other than haemolymph volume. Haemolymph protein measurements and calculated respiratory exchange ratios suggest that catabolism of haemolymph proteins may contribute to a reduced haemolymph buffering capacity, and thus a compromised ability for CO2 accumulation, in solitary locusts. Nevertheless, DGC was lost at similar hydration states in the two phases, suggesting that DGCs are terminated as a result of inadequate oxygen supply to the tissues.

Effects of the buffering capacity of the soil on the mobilization of heavy metals. Equilibrium and kinetics

Understanding the possible pH-buffering processes is of maximum importance for risk assessment and remediation feasibility studies of heavy-metal contaminated soils. This paper presents the results about the effect of the buffering capacity of a polluted soil, rich in carbonates, on the pH and on the leaching evolution of its main contaminant (lead) when a weak acid (acetic acid) or a strong one (nitric acid) are slowly added. In both cases, the behavior of lead dissolution could be predicted using available (scientifically verified freeware) models assuming equilibrium between the solid and the aqueous phase. However, the experimental results indicate that the dissolution of calcium and magnesium carbonates is kinetically controlled. These kinetic limitations affect the overall behavior, and should be considered to understand also the response of the metals under local equilibrium. The well-known BCR sequential extraction procedure was used before- and after-treatment, to fractionate the lead concentration in the soil according to its mobility. The BCR results were also in agreement with the predictions of the equilibrium model. This agreement allows new insights about the information that could be derived from the BCR fractionation analysis.

Effect of pH buffering capacity and sources of dietary sulfur on rumen fermentation, sulfide production, methane production, sulfate reducing bacteria, and total Archaea in in vitro rumen cultures

The effects of three types of dietary sulfur on in vitro fermentation characteristics, sulfide production, methane production, and microbial populations at two different buffer capacities were examined using in vitro rumen cultures. Addition of dry distilled grain with soluble (DDGS) generally decreased total gas production, degradation of dry matter and neutral detergent fiber, and concentration of total volatile fatty acids, while increasing ammonia concentration. High buffering capacity alleviated these adverse effects on fermentation. Increased sulfur content resulted in decreased methane emission, but total Archaea population was not changed significantly. The population of sulfate reducing bacteria was increased in a sulfur type-dependent manner. These results suggest that types of dietary sulfur and buffering capacity can affect rumen fermentation and sulfide production. Diet buffering capacity, and probably alkalinity, may be increased to alleviate some of the adverse effects associated with feeding DDGS at high levels.

Acidogenic fermentation of food waste for volatile fatty acid production with co-generation of biohydrogen

Fermentation experiments were designed to elucidate the functional role of the redox microenvironment on volatile fatty acid (VFA, short chain carboxylic acid) production and co-generation of biohydrogen (H2). Higher VFA productivity was observed at pH 10 operation (6.3g/l) followed by pH 9, pH 6, pH 5, pH 7, pH 8 and pH 11 (3.5 g/l). High degree of acidification, good system buffering capacity along with co-generation of higher H2 production from food waste was also noticed at alkaline condition. Experiments illustrated the role of initial pH on carboxylic acids synthesis. Alkaline redox conditions assist solubilization of carbohydrates, protein and fats and also suppress the growth of methanogens. Among the carboxylic acids, acetate fraction was higher at alkaline condition than corresponding neutral or acidic operations. Integrated process of VFA production from waste with co-generation of H2 can be considered as a green and sustainable platform for value-addition.

Effect of Diuretics on Salivary Flow, Composition and Oral Health Status: A Clinico-biochemical Study

Background:

Saliva represents an increasingly useful tool of diagnosis. Several factors such as salivary flow rates (SFRs) (unstimulated and stimulated) (U and S), pH, buffering capacity and consistency can be altered due to several disease processes or medications prescribed for various diseases. Alterations of SFRs, pH, buffering capacity and various ion concentrations can influence the pathogenesis of some of the oral diseases.

Aim:

Evaluation of the effect of diuretics on oral health status with regard to SFRs (U and S), pH, buffering capacity, total protein content, various ion concentrations and oral mucosal lesions.

Subjects and Methods:

A total of 100 patients were categorized into test group and control group based on usage of diuretics. Unstimulated and stimulated saliva were collected and evaluated for flow rates. Salivary pH was measured using pH meter. Buffering capacity was measured using Aranha's technique. Salivary Na⁺, K⁺ and Cl⁻ concentrations were measured using electrolyte analyzer CORNLEY ACCULYTE-3P in ion-selective electrode method. Salivary total protein content was measured by spectrophotometric method. Dental Caries and periodontal status were measured by using decayed, missing, filled teeth index and Russell's periodontal index respectively. Oral mucosal examination was carried out to identify the mucosal lesions.

Results:

The obtained results were subjected to statistical analysis using Statistical package for social sciences software (SPSS), version 16, IBM Company by Chi-square test and unpaired t-test. Highly significant P for alterations of SFR/U (P < 0.001), SFR/S (P < 0.001), pH (P < 0.001), Na⁺ concentration (P < 0.001), buffering capacity (P < 0.001) and moderate significance for Cl⁻ concentration (P < 0.01) were found. Alterations of total protein (P = 0.14) and K⁺ (P = 0.65) concentrations were not statistically significant. High prevalence was found for caries (P < 0.01), periodontal status (P < 0.001) and mucosal lesions (P < 0.01).

Conclusion:

Our study shows that diuretic medication significantly reduces SFRs (xerostomia) and alters salivary composition which may have an impact on the incidence of dental caries, periodontal diseases and mucosal lesion formation.

Enhanced intracellular uptake and endocytic pathway selection mediated by hemocompatible ornithine grafted chitosan polycation for gene delivery

Nanotechnology is adopted in gene therapy research to create gene vectors that will facilitate gene transfer to cells with utmost efficacy and safety. For vector design, polymers are the preferred nonviral colloidal systems as they are feasible for any chemical modifications. In this study, chitosan, a versatile biopolymer has been subjected to chemical conjugation with the amino acid ornithine to generate chitosan-ornithine conjugate (CON) for gene delivery. With the help of FTIR and (1)H NMR spectra the chemical composition of the chitosan derivative was confirmed. Buffering capacity was found enhanced with the synthesised chitosan derivative when compared to the parent unmodified chitosan. The cationic derivative formed nanoparticles when mixed with negatively charged DNA. The nanoparticles showed good DNA retardation ability in agarose gel electrophoresis and sizes were ascertained by DLS and TEM observations. The derivative on interaction with blood plasma showed negligible protein adsorption and did not cause either hemolysis or RBC aggregation in blood. In vitro cell culture also revealed the CON derivative to be nontoxic to cells and capable of transfection with an explicit increase in cellular uptake of nanoparticles. An uptake study in the presence of endocytosis inhibitors indicated the specific pathway used for cell entry. The results revealed that the clathrin mediated pathway and dynamin played a role in the internalisation of these specific nanoparticles.