Effect Of Protective Agents Research Articles

Screening of Lactiplantibacillus plantarum 67 with Strong Adhesion to Caco-2 Cells and the Effects of Protective Agents on Its Adhesion Ability during Vacuum Freeze Drying.

Adhesion to the intestinal tract provides the foundation for Lactobacillus to exert its benefits. Vacuum freeze-drying (VFD) is currently one of the main processing methods for Lactobacillus products. Therefore, the effects of VFD on the adhesion and survival of Lactiplantibacillus plantarum 67 were investigated in this study. The results show that L. plantarum 67 exhibits remarkable tolerance following successive exposure to simulated saliva, gastric juice and intestinal juice, and also has a strong adhesion ability to Caco-2 cells. The adhesion and survival rates of L. plantarum 67 significantly decreased after VFD in phosphate-buffered saline (PBS), whereas they significantly increased in protective agents (PAs) (p < 0.05). Scanning electron microscope observations show that L. plantarum 67 aggregated more to Caco-2 cells in PAs than in PBS, and its shape and size were protected. Proteomics detection findings indicated that differentially expressed proteins (DEPs) related to adhesins and vitality and their pathways in L. plantarum 67 were significantly affected by VFD (p < 0.05). However, the expression of DEPs (such as cold shock protein, cell surface protein, adherence protein, chitin-binding domain and extracellular transglycosylase, membrane-bound protein) was improved by PAs. Compared with PBS, the PAs significantly adjusted the phosphotransferase system and amino sugar and nucleotide sugar metabolism pathways (p < 0.05). VFD decreased the adhesion and vitality of L. plantarum 67, while the PAs could exert protective effects by regulating proteins and pathways related to adhesion and vitality.

Effect of protective agents on the storage stability of freeze-dried Ligilactobacillus salivarius CECT5713.

Ligilactobacillus salivarius is a lactic acid bacterium exhibiting several health benefits but remains commercially underexploited due to its inability to survive during long-term storage in the dried state. Our objective was to study the effect of various protective molecules (maltodextrin, trehalose, antioxidants, and fructooligosaccharides), being efficient on other bacteria, on the freeze-dried stability of L. salivarius CECT5713. The culturability was evaluated after freezing, freeze-drying, and subsequent storage at 37°C, as well as the biochemical composition of cells in an aqueous environment using Fourier transform infrared (FTIR) micro-spectroscopy. The assignment of principal absorption bands to cellular components was performed using data from the literature on bacteria. The membrane fatty acid composition was determined after freeze-drying and storage. Glass transition temperature of the liquid and freeze-dried bacterial suspensions and water activity of the freeze-dried samples were measured. The best storage stability was observed for the formulations involving maltodextrin and antioxidants. The analysis of the FTIR spectra of freeze-thawed cells and rehydrated cells after freeze-drying and storage revealed that freeze-drying induced damage to proteins, peptidoglycans of the cell wall and nucleic acids. Storage stability appeared to be dependent on the ability of the protective molecules to limit damage during freeze-drying. The inactivation rates of bacteria during storage were analyzed as a function of the temperature difference between the product temperature during sublimation or during storage and the glass transition temperature, allowing a better insight into the stabilization mechanisms of freeze-dried bacteria. Maintaining during the process a product temperature well below the glass transition temperature, especially during storage, appeared essential for L. salivarius CECT5713 storage stability. KEY POINTS: • L. salivarius CECT5713 highly resisted freezing but was sensitive to freeze-drying and storage. • Freeze-drying and storage mainly altered cell proteins, peptidoglycans, and nucleic acids. • A glassy matrix containing maltodextrin and an antioxidant ensured the highest storage stability.

N-Acetyl Cysteine Ameliorates Hepatotoxicity Associated with the Use of Methotrexate in Mice

Background: Liver is not only involved in maintaining homeostasis but also exhibits significant role in metabolism and detoxification of various drugs and toxins. Aim: To explore the hepato-protective role of N-acetylcysteine against methotrexate induced hepato-toxicity. Study design: Randomized controlled trial. Methodology: This study having mice (n=18) was carried out after ethical review committee’s (ERC) approval at Foundation university medical college in collaboration of National institute of health, Islamabad in 2017. Single intraperitoneal injection (20mg/kg) of methotrexate induced hepato-toxicity. Hepatoprotective effect was assessed by oral administration N-acetylcysteine (50mg/kg) alone with methotrexate. The extent of liver damage and effect of protective agents were determined by measuring serum ALT, AST, ALP after 24 hours of respective treatment. Liver samples were taken for histological analysis. One way ANOVA followed by Post Hoc Tukey test was applied for multiple comparisons of biochemical markers between the groups. Histopathological findings were analyzed by Chi Square test. p &lt; 0.05 was considered significant. Results: Significant (p &lt; 0.05) hepatotoxicity was seen with substantial elevation in serum ALT, AST and ALP with methotrexate. N-acetylcysteine attenuated the methotrexate induced hepatotoxicity significantly (p &lt; 0.05). The histopathological examination showed mild steatosis along with focal pleomorphism in the liver of mice that received methotrexate in comparison to group treated with N-acetylcysteine and methotrexate though minimal inflammation was seen. Conclusion: We concluded that N-acetylcysteine ameliorates the methotrexate induced hepatotoxicity on when used concomitantly. Keywords: Hepatotoxicity, N-acetylcysteine and Methotrexate

Effect of Protective Agents on Silver Nanoparticle Preparation by Vacuum Evaporation on Running Hydrocarbon Solution.

In order to simply compare the performance of protective agents in the preparation of metal nanoparticles, a systematic investigation based on the same synthetic conditions is necessary. We successfully achieved this objective using improved vacuum evaporation on running oil substrate (VEROS) method. The efficient synthesis of nanoparticles with the improved VEROS method enabled us to characterize them by various analytical methods. In this study, five types of protective agents with different functional groups were employed to clarify their effect on the preparation of silver nanoparticles. They are sorbitan monooleate, oleylamine, oleic acid, oleyl alcohol, and methyl oleate. Particles synthesized by the improved VEROS method were evaluated by transmission electron microscope (TEM) and UV-vis spectrophotometer. These results indicate that sorbitan monooleate and oleic acid effectively protect the aggregation between particles. It is also evident from the evaluation of powdered nanoparticles isolated from the trap solution by thermogravimetric analysis (TGA) that these protective agents adsorb on the surface of the particles. On the other hand, the aggregates of silver nanoparticles were formed in the cases using oleic alcohol and methyl oleate. Silver nanoparticles were obtained in the case of oleylamine but the material efficiency of silver was extremely low. As a result, our systematic investigation using the improved VEROS method disclosed suitable protective agents in the preparation of silver nanoparticles with the physical method.

Effect of protective agents on lactic acid bacteria of koumiss powder by vacuum freeze-drying

In order to improve the viable count of lactic acid bacteria in koumiss powder produced by vacuum freeze- drying, 3 kinds of freeze- drying protective agents were screened by two level fractional factorial design,and the central point of response surface experiment was confirmed by the steepest ascent experiment.The optimal additions of 3 freeze-drying protective agents were 2.30%(W/V) of maltodextrin,3.50%(W/V) of trehalose and 3.10%(W/V) of α-cyclodextrin. Under the optimal conditions,the viable count of lactic acid bacteria in koumiss powder was up to(8.78±0.10)×108CFU/g.The freeze-drying koumiss powder had higher viable count of lactic acid bacteria and good flavor and quality,which could provide theoretical basis for processing of mare's milk and its' production.

Effect of protective agents and previous acclimation on ethanol resistance of frozen and freeze-dried Lactobacillus plantarum strains

The aim of this work was to study the protective effect of sucrose, trehalose and glutamate during freezing and freeze-drying of three oenological Lactobacillus plantarum strains previously acclimated in the presence of ethanol. The efficiency of protective agents was assessed by analyses of membrane integrity and bacterial cultivability in a synthetic wine after the preservation processes. No significant differences in the cultivability, with respect to the controls cells, were observed after freezing at −80 °C and −20 °C, and pre-acclimated cells were more resistant to freeze-drying than non-acclimated ones. The results of multiparametric flow cytometry showed a significant level of membrane damage after freeze-drying in two of the three strains. The cultivability was determined after incubation in wine-like medium containing 13 or 14% v/v ethanol at 21 °C for 24 h and the results were interpreted using principal component analysis (PCA). Acclimation was the most important factor for preservation, increasing the bacterial resistance to ethanol after freezing and freeze-drying. Freeze-drying was the most drastic method of preservation, followed by freezing at −20 °C. The increase of ethanol concentration from 6 to 10% v/v in the acclimation medium improved the recovery of two of the three strains. In turn, the increase of ethanol content in the synthetic wine led to a dramatic decrease of viable cells in the three strains investigated. The results of this study indicate that a successful inoculation of dehydrated L. plantarum in wine depends not only on the use of protective agents, but also on the cell acclimation process prior to preservation, and on the ethanol content of wine.

Applicability of In Vitro Methods to Study Patulin Bioaccessibility and Its Effects on Intestinal Membrane Integrity

In human health risk assessment, ingestion of food is considered a major route of exposure to many contaminants, although the total amount of an ingested contaminant (external dose) does not always reflect the quantity available for the body (internal dose). In this study, two in vitro methods were applied to study bioaccessibility and intestinal membrane integrity of cells exposed to patulin, a mycotoxin with significant public health risk. Seven artificially contaminated fruit juices were assayed in the presence or absence of a standard meal, showing a significant difference for bioaccessibility values between contaminated samples alone (mean 27.65 ± 13.50%) and combinations with a standard meal (mean 7.89 ± 4.03%). Different concentrations of patulin (PAT) and cysteine (CYS) (protector agent) were assayed in Caco-2 cells monolayers. At 95 μM, PAT produced a marked decrease in transepithelial electrical resistance (TEER). This effect was significantly reduced when 400 μM and 4000 μM CYS was added to the cells. Combined use of in vitro digestion models with other techniques using intestinal cell lines, such as in vitro intestinal absorption models that use Caco-2 cells, may offer a more comprehensive model of what is occurring during digestion and absorption processes. The study of beneficial effects of protective agents would also be enhanced.

A Nano-Silver Inkjet Conductive Ink with Excellent Adhesion

In this paper，the preparation of a solvent based nano-silver inkjet conductive ink with excellent adhesion was investigated and applied. Nano-silver particles, with dodecylamine (DDA) as the protective agent, were prepared and the effect of protective agent on the post heat-treatment of nano- silver films was investigated. Results of electrical resistance, micro-structural evolution and thermal analysis showed that the Ag/DDA films require a relatively low treatment temperature to convert into conductive materials. Then the conductive ink was prepared with well dispersed Ag/DDA nanoparticles and the ink was printed patterns on PET、PI films through EPSON ME 33 inkjet printer , the patterns showed a sheet resistance is 182.3mΩ/□ and the adhesion reached to 5B after heat-treating at 120°C for 60min .

Drying kinetics and survival studies of dairy fermentation bacteria in convective air drying environment using single droplet drying

The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45–95°C) at a constant air velocity (0.5m/s) and within 2.4–11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (⩾65°C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (⩽55°C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8kJ/mol) within the medium temperature of 45–95°C.

Study on the Optimal Isolation Technique of Superoxide Dismutase from Pig and Bovine Blood Block

Double, three factor-test and orthogonal designs were employed to study the effect of protective agent, membranolytic agent, activating agent, denaturalization temperature and denaturalization time on SOD extracted from pig and bovine blood block. The results of double and three factor-tests show that the variance between pig and bovine blood block was obviously significant (P&lt;0.01). The mixture protective agent was better than single, the best was 1.5% galactosylglucose + 0.5% β-cyclodextrin + 0.25% PEG, and the better membranolytic agent was 3% Triton X-100 + 0.5% n-butyl alcohol for bovine blood, and 3% Triton X-100 for pig blood. The optimal dosage of protective agent was 20% of blood block weight, the optimal dosage of membranolytic agent was 15-20% of blood block weigh, and the best optimal dosage of activator was 2.5%. The best optimal combination of orthogonal experiment for bovine blood block was A2B2C2, and the best optimal combination of pig blood was A1B1C2. Under those conditions, the activity of SOD exceeded 3000 U/mg protein.

Assessment of urinary albumin excretion might improve cardiovascular outcome in patients with hypertension

This Practice Point commentary discusses a study by Boersma et al. that aimed to investigate whether the efficacy of blood-pressure-lowering agents depends on a patient's level of urinary albumin excretion before initiation of treatment. Boersma et al. reported that the higher baseline albuminuria is in hypertension, the better the relative and absolute risk reductions for cardiovascular events with antihypertensive drugs. Their data also suggested that the cardiovascular protective effect of agents that interfere with the renin–angiotensin–aldosterone system in patients with elevated urinary albumin excretion is better than that of other blood-pressure-lowering agents. Here, the importance of measuring urinary albumin excretion in clinical practice to improve the cardiovascular prognosis of hypertensive patients will be discussed. The many potential pitfalls of this observational study are highlighted and the need for well-designed, large, randomized trials in the area is emphasized.

Effect of Protective Agents on the Viability of Geotrichum candidum during Freeze‐Drying and Storage

The effect of 3 cryoprotective agents (trehalose, sucrose, and maltose) on the survival of concentrated cultures of Geotrichum candidum was studied. Initially, the effect of the carbohydrates at 9% and 23% concentrations or combined with skim milk (16%) was compared to the control (skim milk alone) immediately after freeze-drying. Two freeze-drying shelf temperatures, 25 degrees C and 35 degrees C, were investigated. Afterwards, the survival of G. candidum freeze-dried with carbohydrates at 23% concentration (alone or combined with skim milk 16%) was studied during 12 wk of storage at 4 degrees C, in the darkness, under vacuum, and at 0% relative humidity. The glass transition temperature (T(g)) of the dehydrated protective agents was measured by differential scanning calorimetry. The results showed that the survival after freeze-drying was proportional to the concentration of the protective agents, with skim milk alone giving poor survival of G. candidum. However, when skim milk was combined with disaccharides, a clear improvement was noted. No general tendency of shelf temperature on the survival of G. candidum was noted immediately after freeze-drying. However, changes in the viability were observed during storage. Glass transition temperature (T(g)) of protective agents linked to their moisture may contribute to predict the stability of lyophilized G. candidum during freeze-drying and storage.

Effect of protective agents on the viability of Lactococcus lactis subjected to freeze-thawing and freeze-drying

The effect of different protectants and the impact of the initial cell density on the viability of Lactococcus lactis Sr. 3.54 subjected to freeze-thawing and freezedrying was studied. Several additives were tested as protective agents against freezing and drying injuries. Maximum viability of the cells after freeze-thawing was obtained with sucrose and skim milk mixtures as protective agents (78% viability). Freeze-drying with protectants based on skim milk or MRS-broth were most effective (survival levels >60%). The effect of the initial cell load on the final recovery was dependent on the protectant. Every sample showed an increase in viability when a high initial cell concentration (1010cfu ml-1) was used. The blank showed a 1500 fold increase, skim milk/sucrose based lyophilisates an 1,7 fold increase in viability when the initial cell load was changed from 1009 to 1010cfu ml-1. The use of 1010cfu ml-1 as initial cell concentration and sucrose/skim milk as protectant yielded a lyophilisate with 71% viability. Results suggest the possibility of producing freeze dried powders of Lactococcus lactis with high viability for the food industry.

Effect of protective agents, freezing temperature, rehydration media on viability of malolactic bacteria subjected to freeze-drying

The effects of protective agents, rehydration media and freezing temperature on the viabilities of Lactobacillus brevis and Oenococcus oeni H-2 when subjected to freeze-drying were investigated. Several protectants and rehydration media were tested to improve the survival after freeze-drying. The cells were also frozen at -65 and -20 degrees C to check the effect of freezing temperature on the viability. The best protectant and rehydration medium to obtain the highest viability after freeze-drying varied with the species of bacteria. Yeast extract (4.0%) and sodium glutamate (2.5% ) gave maximum viability of L. brevis and O. oeni (67.8% and 53.6% respectively). The highest survival of L. brevis and O. oeni were obtained when rehydrated with 10% sucrose and MGY medium respectively. When the bacterial cells were frozen quickly (-65 degrees C) than slowly (-20 degrees C), L. brevis and O. oeni both showed increased viability after freeze-drying. The viabilities of L. brevis and O. oeni after freeze-drying were shown to be strain specific and dependent on protective agents, rehydration media and freezing temperature.

Preparation of DNA dry powder for non-viral gene delivery by spray-freeze drying: effect of protective agents (polyethyleneimine and sugars) on the stability of DNA.

This study investigates the feasibility of using the process of spray-freeze drying (SFD) to produce DNA dry powders for non-viral gene delivery. The effect of protective agents was assessed on the stability of DNA dry powders after SFD. The process of SFD had adverse effects on the tertiary structure of DNA with the protective agents of sucrose, trehalose and mannitol. With the protection of these sugars, a band corresponding to the linear form of DNA was observed during gel electrophoresis between the supercoiled form (SC) and the open circular (OC) form. On the contrary, excess cationic condensing polyethyleneimine (PEI), in conjunction with the above sugars, had the ability to provide protection for DNA from degradation after SFD. This is indicated by the reservation in SC and OC forms of DNA during agarose gel electrophoresis. The electrostatic forces between PEI polymer and DNA are critical for providing protection against various stresses generated by the process of SFD. Furthermore, on rehydration, the particle size and zeta potential of PEI/DNA complexes at weight ratios 3:1 of SFD dry powders were well maintained. Also, no transfection activity loss of PEI/DNA complexes at weight ratios 3:1 on NIH/3T3 cells was observed for reconstituted powders as compared with untreated control solutions. These results give a better understanding of preparing stable DNA dry powders by the process of SFD.

The effect of protective agents on the stability of plasmid DNA by the process of spray-drying.

The effect of several protective agents was assessed on the stability of spray-dried plasmid DNA. The spray-drying process had adverse effects on the tertiary structure of plasmid DNA with the protective agents of sucrose, glycine and agarose. With the protection of these noncondensing agents, a band corresponding to the linear form of plasmid DNA was observed in the gel electrophoresis between the supercoiled circular (SC) form and the open circular (OC) form. On the contrary, spray-dried plasmid DNA maintained some degree of structural integrity under the protection of condensing agents. For the protection by neutral condensing polymers, such as polyethylene glycol 1000 and 4000, no linear form between the SC form and the OC form of plasmid DNA was revealed in the gel electrophoresis. Also, excess cationic condensing polymer, polyethyleneimine, had the ability to provide the plasmid DNA with protection from degradation as indicated by the preservation in SC and OC forms of plasmid DNA on the agarose gel electrophoresis. Moreover, DNA topology was unchanged after six-month storage at 4 degrees C by the protection of these neutral and cationic condensing agents. Accordingly, DNA condensation induced by condensing agents may provide a way to minimize damage to plasmid DNA by the process of spray drying.

Effect of protective agents, rehydration media and initial cell concentration on viability of Pantoea agglomerans strain CPA-2 subjected to freeze-drying

The effect of initial cell density, protective agents and rehydration media on the viability of biocontrol agent Pantoea agglomerans CPA-2 when subjected to freeze-drying was studied. Several additives were tested as protective agents against freeze-drying injury. Maximum viability of the bacterial cells was obtained with disaccharides (survival levels > 60%). Freeze-dried samples were rehydrated with several media; the highest percentage viability was obtained with 10% non-fat skim milk (100%+). The effect of initial bacterial load on the final recovery was dependent on protectant but not on rehydration media. Sucrose was an effective protectant when a high initial concentration (10(10) cfu ml(-1) was used; the opposite occurred with non-fat skim milk. The use of 10(10) cfu ml(-1) as an initial concentration, sucrose as a protectant and non-fat skim milk as a rehydration medium enabled 100% of P. agglomerans viability to be conserved after freeze-drying. Results suggest the possibility of achieving a good formulation system for the studied biocontrol agent with a high number of viable cells to be used toward pathogens, which is desirable for the industrial development of the product.

Molecular and cellular events associated with aflatoxin-induced hepatocarcinogenesis

Abstract

Effectiveness of protective agents for increasing activity of five enzymes from vegetative tissues of white spruce

Optimal conditions of pH and substrate concentration for five enzymes from crude extracts of needle and bud tissue of a white spruce (Picea glauca (Moench) Voss) tree were first investigated, and then used for subsequent experiments. With increasing age of the needles on the tree, activity of peroxidase increased, while that of 6-phosphogluconic acid dehydrogenase and ferredoxin-NADP+ reductase decreased. Polyethylene glycol increased enzyme activity from needle tissue. For isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase, 2% polyethylene glycol was most effective, while for 6-phosphogluconic acid dehydrogenase, 4% was best. Enzyme activity also varied considerably with the pH of the extraction buffer. Extraction of needle and bark tissues with various combination buffers referred to in the literature clearly indicated that no one extraction buffer was optimal for all five enzymes of this study. Unlike that of needle and bark tissues, enzyme activity of bud tissues was high even in the absence of any protective agent. The effect on enzyme activity of storage of the bud extracts for 10 days at 4 °C varied with the enzyme.

Effect of protective agents on amount and repair of sublethal freeze-thaw damage in mammalian cells

Glycerol, DMSO, and HES are able to reduce by a factor of 2 the sublethal damage produced in mammalian cells after one freeze-thaw cycle. When sublethal freeze-thaw damage is already present, DMSO and HES are able to prevent about half of this damage from becoming lethal when a second freeze-thaw cycle is applied. Glycerol is only able to do this if dilution shock is avoided by thawing the cells into medium containing glycerol. The cells can repair 100% of this sublethal damage and do so in 2–3 hr at 37 °C in suspension. The data imply that the sites protected by DMSO, HES, and glycerol are the same as the sites repaired by the cells. The results also suggest that cells stop progressing in the cell cycle while repairing sublethal freeze-thaw damage.