ABSTRACT
The effect of different carbon sources on bacterial cellulose production by Gluconacetobacter xylinus [PTCC 1734] and two newly isolated strains [from vinegar] under static culture conditions was studied
The production of bacterial cellulose was examined in modified Hestrin-Shramm medium by replacing D-glucose with other carbon sources
The results showed that the yield and characteristics of bacterial cellulose were influenced by the type of carbon source. Glycerol gave the highest yield in all of the studied strains [6%, 9.7% and 3.8% for S, A[2] strain and Gluconacetobacter xylinus [PTCC 1134], respectively
The maximum dry bacterial cellulose weight in the glycerol-Icontaining medium is due to A[2] strain [1.9 g I[-1]] in comparison to Gluconacetobacter xylinus as reference strain [0.76 g I[-1]]
Although all of the studied strains were in Gluconacetobacter family, each used different sugars for maximum production after glycerol [mannitol and fructose for two newly isolated strains and glucose for Gluconacetobacter xvlinus]
The maximum moisture content was observed when sucrose and food-grade sucrose were used as carbon source
Contrary to expectations, while the maximum thickness of bacterial cellulose membrane was attained when glycerol was used, bacterial cellulose from glycerol had less moisture content than.the others
The oxidized cellulose showed antibacterial activities, which makes it as a good candidate for food-preservatives
ABSTRACT
Objectives: this study aimed to compare the in vitro cytotoxic activity of propolis, a bioactive material made by the honeybee, and calcium hydroxide [CH] and their effect on formation of mineralized nodules by human dental pulp stem cells [HDPSCs]
Methods: in this in vitro study, HDPSCs were obtained from the Cellular and Molecular Oral Biology Laboratory of School of Dentistry, Shahid Beheshti University of Medical Sciences. In order to evaluate the proliferative effect of propolis and CH, HDPSCs were incubated with different concentrations of propolis [0-32mg/mL] and CH [0-4.8 mg/mL]. Twenty-four and 48 hours later, the methylthiazolyl diphenyl-tetrazolium bromide [MTT] assay was carried out to evaluate the proliferation potential and viability of HDPSCs treated with propolis and CH. The effect of propolis and CH on mineralization of HDPSCs was assessed by alizarin red staining
Results: the MTT assay revealed that propolis at its highest concentration caused the greatest proliferation after 24 and 48 hours. Alizarin test showed that the lowest concentrations of CH and propolis at 14 days induced the formation of calcium nodules but at 21 days, propolis was deposited on the cells and calcification was not well recognizable
Conclusion: propolis led to higher cell vitality at all concentrations in comparison to CH. However, due to its deposition on the cells, its effects on mineralization at 48 hours could not be determined
ABSTRACT
5-Hydroxymethylfurfural [5-HMF] is known as an indicator of quality deterioration in a wide range of foods. The current study covered 70 samples taken from domestically produced foods and drinks available on the Iranian market [including honey, jam, fruit cakes tomato paste, ketchup, syrup, fruit juice, canned fruit, ultra-high-temperature [UHT] milk, instant coffee, and jelly powder]. HMF levels were determined using high performance liquid chromatography [HPLC] and ultraviolet [UV] detector. The mean recovery values ranged from 84.4 to 105.8%. Varying amounts [11.42-929 mg kg-1] of HMF were found in 48 out of the 70 [87%] samples analyzed. High levels of HMF were mainly seen in commercial honey [20.55 928.96 mg kg-1], jams [51.10 to 245.97 mg kg-1], fruit cakes [nd-171.50 mg kg-1], and ketchup [32.70-72.19 mg kg-1]. No HMF content was detected in UHT milk, instant coffee, and jelly powder. The results of our study suggest that, apart from honey, a number of other food commodities, including those containing fruit and/or sugar, hold considerable amounts of HMF. Therefore monitoring of HMF levels in foods seems to be necessary
ABSTRACT
Evaluation of the effect of Propolis as a bioactive material on quality of dentin and presence of dental pulp stem cells. For conducting this experimental split-mouth study, a total of 48 maxillary and mandibular incisors of male guinea pigs were randomly divided into an experimental Propolis group and a control calcium hydroxide group. Cutting the crowns and using Propolis or calcium hydroxide to cap the pulp, all of the cavities were sealed. Sections of the teeth were obtained after sacrificing 4 guinea pigs from each group on the 10th, 15th and 30th day. After they had been stained by hematoxylin and eosin [H and E], specimens underwent a histological evaluation under a light microscope for identification of the presence of odontoblast-like cells, pulp vitality, congestion, inflammation of the pulp and the presence of remnants of the material used. The immunohistochemistry [IHC] method using CD[29] and CD[146] was performed to evaluate the presence of stem cells and the results were statistically evaluated by Kruskal-Wallis, Chi Square and Fisher tests. In H and E stained specimens, there was no difference between the two groups in the presence of odontoblast-like cells, pulp vitality, congestion, inflammation of the pulp and the presence of remnants of used material[p>0.05]. There was a significant difference between the quality of regenerative dentin on the 15[th] and 30[th] days [p<0.05]: all of the Propolis cases presented tubular dentin while 14% of the calcium hydroxide cases produced porous dentin. There was no significant difference between Propolis and calcium hydroxide in stimulation of dental pulp stem cells [DPSCs]. This study which is the first one that documented the stimulation of stem cells by Propolis, provides evidence that this material has advantages over calcium hydroxide as a capping agent in vital pulp therapy. In addition to producing no pulpal inflammation, infection or necrosis this material induces the production of high quality tubular dentin