Physical/mechanical and antibacterial properties of orthodontic adhesives containing Sr-bioactive glass nanoparticles, calcium phosphate, and andrographolide

White spot lesions around orthodontic brackets are the major complication during fixed orthodontic treatment. This study prepared orthodontic adhesives for promoting mineral precipitation and reducing bacterial growth. Adhesives with added calcium phosphate monohydrate/Sr-bioactive glass nanoparticles (Sr/CaP) and andrographolide were prepared. The physical/mechanical and antibacterial properties of the adhesives were tested. The additives reduced the monomer conversion of the materials (62 to 47%). The addition of Sr/CaP and andrographolide increased the water sorption (from 23 to 46 μg/mm³) and water solubility (from 0.2 to 5.9 μg/mm³) but reduced the biaxial flexural strength (from 193 to 119 MPa) of the adhesives. The enamel bond strengths of the experimental adhesives (19–34 MPa) were comparable to that of the commercial material (p > 0.05). The Sr/CaP fillers promoted Ca, Sr, and P ion release and the precipitation of calcium phosphate at the debonded interface. An increase in the Sr/CaP concentration enhanced the inhibition of S. mutans by 18%, while the effect of andrographolide was not detected. The abilities of the adhesives to promote ion release, calcium phosphate precipitation, and the growth inhibition of cariogenic bacteria were expected to reduce the occurrence of white spot lesions. The additives reduced the physical/mechanical properties of the materials, but the corresponding values were within the acceptable range.

Physical/Mechanical and Antibacterial Properties of Orthodontic Adhesives Containing Calcium Phosphate and Nisin

Enamel demineralization around orthodontic adhesive is a common esthetic concern during orthodontic treatment. The aim of this study was to prepare orthodontic adhesives containing monocalcium phosphate monohydrate (MCPM) and nisin to enable mineralizing and antibacterial actions. The physicomechanical properties and the inhibition of S. mutans growth of the adhesives with added MCPM (5, 10 wt %) and nisin (5, 10 wt %) were examined. Transbond XT (Trans) was used as the commercial comparison. The adhesive containing a low level of MCPM showed significantly higher monomer conversion (42–62%) than Trans (38%) (p < 0.05). Materials with additives showed lower monomer conversion (p < 0.05), biaxial flexural strength (p < 0.05), and shear bond strength to enamel than those of a control. Additives increased water sorption and solubility of the experimental materials. The addition of MCPM encouraged Ca and P ion release, and the precipitation of calcium phosphate at the bonding interface. The growth of S. mutans in all the groups was comparable (p > 0.05). In conclusion, experimental orthodontic adhesives with additives showed comparable conversion but lesser mechanical properties than the commercial material. The materials showed no antibacterial action, but exhibited ion release and calcium phosphate precipitation. These properties may promote remineralization of the demineralized enamel.

Vibration synergistically enhances IL-1β and TNF-α in compressed human periodontal ligament cells in the frequency-dependent manner

Objectives

To investigate whether mechanical vibration at 30 or 60 Hz combined with compressive force alter IL-1β and TNF-α expression in human periodontal ligament (hPDL) cells.

Methods

hPDL cells isolated from the roots of first premolar teeth extracted from four independent donors were cultured and exposed to vibration (0.3 g, 20 min per cycle, every 24 h for 3 cycles) at 30 or 60 Hz (V30 or V60), 2.0 g/cm² compressive force for 2 days (CF), or a combination of compressive force and vibration at 30 Hz or 60 Hz (V30CF or V60CF). Quantitative real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assays (ELISAs) were used to determine IL-1β and TNF-α mRNA and protein, respectively.

Results

The levels of IL-1β and TNF-α did not alter in groups V30 and V60. While, they were upregulated in groups CF, V30CF and V60CF. In addition, IL-1β mRNA and TNF-α mRNA and protein were expressed at significantly higher levels in group V30CF compared to CF group. However, IL-1β protein levels between V30CF and CF groups did not reach statistical significance.

Conclusions

30 Hz vibration had the synergistic effects with compressive force on the upregulation of IL-1β mRNA and TNF-α mRNA and protein in PDL cells, while 60 Hz vibration did not have this synergistic effect.

Low magnitude high frequency vibration induces RANKL via cyclooxygenase pathway in human periodontal ligament cells in vitro

Objective

This study aimed to examine the effects of PGE2 on RANKL expression in response to vibration and vibration in combination with compressive stress and characterise this transduction pathway in periodontal ligament (PDL) cells.

Methods

Cultured human PDL cells obtained from extracted premolar teeth (from six individuals) were subjected to three cycles of vibration (0.3 g, 30 Hz for 20 min every 24 h; V), compressive stress (1.5 g/cm², 48 h; C) or vibration in combination with compressive stress (VC). To investigate whether the expression of RANKL and PGE2 was COX-dependent, PDL cells were treated with indomethacin prior to the onset of mechanical stimulation. RANKL and OPG expressions were examined by quantitative real-time polymerase chain reaction (qPCR). Quantification of PGE2, soluble RANKL (sRANKL) and OPG productions were measured using enzyme-linked immunosorbent assay (ELISAs).

Results

All mechanical stresses (V, C and VC) significantly increased PGE2 and RANKL. OPG was not affected by vibration, but was downregulated in compressed cells (C and VC). Indomethacin abolished induction of RANKL and downregulated OPG in response to all mechanical stresses.

Conclusion

These results suggest that vibration, compressive stress and vibration in combination with compressive stress induce RANKL expression in human PDL cells by activating the cyclooxygenase pathway.

Effects of low magnitude high frequency mechanical vibration combined with compressive force on human periodontal ligament cells in vitro

Objective

Vibration can be used to accelerate tooth movement, though the exact mechanisms remain unclear. This study aimed to investigate the effects of low magnitude high frequency (LMHF) vibration combined with compressive force on periodontal ligament (PDL) cells in vitro.

Materials and methods

Human PDL cells were isolated from extracted premolar teeth of four individuals. To determine the optimal frequency for later used in combination with compressive force, three cycles of low-magnitude (0.3 g) vibrations at various frequencies (30, 60, or 90 Hz) were applied to PDL cells for 20 min every 24 h. To investigate the effects of vibration combined with compressive force, PDL cells were subjected to three cycles of optimal vibration frequency (V) or 1.5 g/cm2 compressive force for 48 h (C) or vibration combined with compressive force (VC). Cell viability was assessed using MTT assay. PGE2, soluble RANKL (sRANKL), and OPG production were quantified by ELISA. RANKL, OPG, and Runx2 expression were determined using real-time PCR.

Results

Cell viability was decreased in groups C and VC. PGE2 and RANKL, but not OPG, were increased in groups V, C, and VC, thus increasing the RANKL/OPG ratio. The highest level was observed in group VC. sRANKL was increased in groups V, C, and VC; however, no significant different between the experimental groups. Runx2 expression was reduced in groups C and VC.

Conclusions

Vibration increased PGE2, RANKL, and sRANKL, but not OPG and Runx2. Vibration had the additive effects on PGE2 and RANKL, but not sRANKL in compressed PDL cells.

Use of TPP and ATPS for partitioning and recovery of lipase from Pacific white shrimp (Litopenaeus vannamei) hepatopancreas

Lipase recovery from Pacific white shrimp hepatopancreas using a three-phase partitioning (TPP) system in combination with an aqueous two-phase system (ATPS) was studied. TPP system was formed with a simultaneous addition of salt directly to crude extract (CE) followed by an organic solvent addition. The various process parameters required for efficient purification of lipase were optimized. The best lipase yield (87.41%) and purification fold (PF) (3.49-fold) were obtained in the interphase of TPP system, which consisted of the CE to t-butanol ratio of 1:1 (v/v) in the presence of 50% (w/v) (NH₄)₂SO₄. Subsequently, TPP fraction was subjected to ATPS. Effects of phase compositions including PEG molecular weight and concentration, types and concentration of salts, NaCl addition and system pH on lipase partitioning were investigated. With the application of 25% (w/w) PEG1000 and 15% (w/w) MgSO₄, at pH 5.0 was found most appropriate since high lipase PF (5.19-fold) and yield (78.46%) in top phase were obtained. The partitioned enzyme exhibited optimal activity at pH 8.0 and 55 °C and was stable at a temperature range of 0-40 °C and a pH range of 7-10. The partitioned lipase showed high tolerance in the presence of ethanol and methanol. Hence, the combined partitioning systems, TPP-ATPS, were found to be an attractive technique for the recovery and partial purification of lipase from Pacific white shrimp hepatopancreas.

Differences in textural properties of cooked caponized and broiler chicken breast meat

This study was aimed at evaluating textural properties of cooked chicken breast meats obtained from 3 production systems (conventional raising, feed modification, and caponization) and determining the relationship between instrumental parameters and sensory attributes associated with the texture of capon meat. Texture of cooked breast meats was determined using 3 instrumental methods: Warner-Bratzler Shear (WBS), texture profile analysis (TPA), and uniaxial compression (UC), and sensory analysis by trained panelists. The results indicated that cooked caponized meat showed the lowest values of WBS force, shear energy, hardness, Young's modulus of UC, and the 2 sensory attributes (firmness and number of chews) (P < 0.05). In contrast, springiness and juiciness were the highest in the caponized meat (P < 0.05), suggesting that capon meat was more tender and juicier than the others. Feed-modified chicken samples showed intermediate textural characteristics between the samples of capon and conventionally raised broiler. Pearson's correlation revealed that WBS force, shear energy, Young's modulus of UC, gumminess, and springiness were strongly correlated with 3 sensory attributes (firmness, number of chews, and juiciness). Partial least squares regression (PLSR) demonstrated that 72% of all sensory attributes for the first 2 PLSR components were explained by 36% of the instrumental parameters and the production systems. Loading and score plot illustrated that conventional raising contributed to a high degree of firmness and number of chews, and positively correlated with shear energy, WBS force, gumminess, hardness, and Young's modulus. Contrarily, caponization was negatively correlated with those sensory attributes. The univariate analysis indicated that firmness and number of chews were positively correlated with all instrumental parameters, except springiness. Juiciness was positively correlated with springiness but negatively correlated with the others. The study suggested that the cooked meat of capons could be differentiated from those of broilers raised conventionally and with feed-modified diets based on textural properties. Based on the optimized simulating equation, texture of caponized breast could be explained by WBS force, shear energy, Young's modulus, and gumminess.

Enzymatic hydrolysis of starry triggerfish (Abalistes stellaris) muscle using liver proteinase from albacore tuna (Thunnus alalunga)

Proteinases from liver extract from albacore tuna (Thunnus alalunga) were used to produce protein hydrolysate from starry triggerfish (Abalistes stellaris) muscle. Hydrolysis conditions for preparing protein hydrolysate from starry triggerfish muscle were optimized. Enzyme level, reaction time and fish muscle/buffer ratio significantly affected the hydrolysis (p < 0.05). Optimum conditions for triggerfish muscle hydrolysis were 5.5 % liver extract, 40 min reaction time and fish muscle/buffer ratio of 1:3 (w/v). The freeze-dried protein hydrolysate was characterized with respect to chemical composition, amino acid composition and color. The product contained 91.73 % protein, 2.04 % lipid and 6.48 % ash. The protein hydrolysate exhibited high amount of essential amino acids (45.62 %). It was light yellow in color (L (*) = 82.94, a (*) = 0.84, b (*) = 22.83). The results indicate that the extract from liver of albacore tuna could be used to produce fish protein hydrolysate and protein hydrolysate from starry triggerfish muscle may potentially serve as a good source of desirable peptide and amino acids.

Comparative Study on the Nutritional Value of Pidan and Salted Duck Egg

Pidan and salted duck eggs are of nutritional rich alternative duck egg products which are predominantly consumed in China, Thailand, South Korea and other Chinese migrated countries. Both eggs are rich in proteins, lipids, unsaturated fatty acids and minerals. A Pidan whole egg contains 13.1% of protein, 10.7% of fat, 2.25% of carbohydrate and 2.3% of ash, whereas the salted duck egg contains 14% of protein, 16.6% of fat, 4.1% of carbohydrate and 7.5% of ash. The fresh duck egg contains a range of 9.30-11.80% of protein, 11.40-13.52% of fat, 1.50-1.74% of sugar and 1.10-1.17% of ash. Proteins, lipids, and ash contents are found to be greatly enhanced during the pickling and salting process of pidan and salted duck eggs. However, the alkaline induced aggregation of pidan leads to degradation and subsequent generation of free peptides and amino acids. Very few amino acids are found to be lost during the pickling and storage. However, no such losses of amino acids are reported in salted duck eggs during the salting process of 14 d. Phospholipids and cholesterol contents are lower in pidan oil and salted duck egg yolk oil. Thus, the pidan and salted duck eggs are nutritionally rich alternatives of duck egg products which will benefit the human health during consumption.

Effect of three cations on the stability and microstructure of protein aggregate from duck egg white under alkaline condition

Pidan (alkaline egg) has been consumed widely in oriental countries and lead, a toxic element, has been used traditionally to yield the desirable characteristics. For safety concerns, alternative cations can be used for the production of pidan with comparable properties to traditionally prepared pidan. Turbidity measured as absorbance at 400 nm and microstructure of duck egg white proteins at pH 12 as influenced by three cations at various levels were investigated. Turbidity and particle size of egg white protein (20 g/kg) in 10 g/kg NaCl sample with CaCl2, PbO2 or ZnCl2 added at a level of 1 g/kg increased with time up to 1 h, followed by a decrease (p < 0.05). Nevertheless, the turbidity was retained more in samples added with PbO2, suggesting high stability of the aggregate formed. Zeta potential showed that the aggregates treated with PbO2 had a comparatively lower negative charge. Light microscopic studies indicated that the aggregation of egg white proteins was induced by ions but varied with the types of ions and incubation time. Therefore, PbO2 exhibited the highest stabilizing effect on egg white protein under alkaline condition. However, ZnCl2 can be used as an alternative compound even if it had lower impact on stability of aggregate of duck egg white protein.

Effects of sodium carbonate and sodium bicarbonate on yield and characteristics of Pacific white shrimp (Litopenaeus vannamei)

Effects of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) on yield and characteristics of Pacific white shrimp (Litopenaeus vannamei) were studied. Shrimp soaked in 2.5% NaCl containing both compounds at different levels of pH (5.5, 7, 8.5, 10 and 11.5) showed an increase in the weight gain and cooking yield and a reduced cooking loss as pH of solutions increased (p < 0.05). Increases in pH and salt content in soaked shrimp muscle were obtained with increasing pH (p < 0.05). Higher pH of soaking solution partially solubilized proteins in the muscle as well as carotenoproteins. pH of solutions above 8.5 led to the pronounced leaching of pigments, associated with the lowered redness of cooked shrimp. Shear force of raw and cooked shrimp continuously decreased as pH of solution increased (p < 0.05). Solution containing 2.5% NaCl and 2.0% NaHCO3 (pH 8.5) was recommended for treatment of white shrimp as a promising alternative for phosphates to increase the yield and to lower cooking loss without any negative effect on sensory properties.

Tuna pepsin: characteristics and its use for collagen extraction from the skin of threadfin bream (Nemipterus spp.)

Pepsin from the stomach of albacore tuna, skipjack tuna, and tongol tuna was characterized. Pepsin from all tuna species showed maximal activity at pH 2.0 and 50 degrees C when hemoglobin was used as a substrate. Among the stomach extract of all species tested, that of albacore tuna showed the highest activity (40.55 units/g tissue) (P < 0.05). Substrate-Native-PAGE revealed that pepsin from albacore tuna and tongol tuna consisted of 2 isoforms, whereas pepsin from skipjack tuna had only 1 form. The activity was completely inhibited by pepstatin A, while EDTA (ethylenediaminetetraacetic acid), SBTI (soybean trypsin inhibitor), and E-64 (1-(L-trans-epoxysuccinyl-leucylamino)-4-guanidinobutane) exhibited negligible effect. The activity was strongly inhibited by SDS (sodium dodecyl sulfate) (0.05% to 0.1%, w/v). Cysteine (5 to 50 mM) also showed an inhibitory effect in a concentration dependent manner. ATP, molybdate, NaCl, MgCl(2), and CaCl(2) had no impact on the activity. When tuna pepsin (10 units/g defatted skin) was used for collagen extraction from the skin of threadfin bream for 12 h, the yield of collagen increased by 1.84- to 2.32-fold and albacore pepsin showed the comparable extraction efficacy to porcine pepsin. The yield generally increased with increasing extraction time (P < 0.05). All collagen obtained with the aid of tuna pepsin showed similar protein patterns compared with those found in acid-solubilized collagen. Nevertheless, pepsin from skipjack tuna caused the degradation of alpha and beta components. All collagens were classified as type I with large portion of beta-chain. However, proteins with molecular weight (MW) greater than 200 kDa were abundant in acid-solubilized collagen.

The role of tobacco control policies in reducing smoking and deaths in a middle income nation: results from the Thailand SimSmoke simulation model

OBJECTIVES

With the male smoking prevalence near 60% in 1991, Thailand was one of the first Asian nations to implement strict tobacco control policies. However, the success of their efforts has not been well documented.

METHODS

The role of tobacco control policies are examined using the "SimSmoke" tobacco control model. We first validated the model against survey data on smoking prevalence. We then distinguished the effect of policies implemented between 1991 and 2006 from long-term trends in smoking rates. We also estimated smoking attributable deaths and lives saved as a result of the policies.

RESULTS

The model validates well against survey data. The model shows that by the year 2006, policies implemented between 1991 and 2006 had already decreased smoking prevalence by 25% compared to what it would have been in the absence of the policies. Tax increases on cigarettes and advertising bans had the largest impact, followed by media anti-smoking campaigns, clean air laws and health warnings. The model estimates that the policies saved 31 867 lives by 2006 and will have saved 319,456 lives by 2026.

CONCLUSIONS

The results document the success of Thailand in reducing smoking prevalence and reducing the number of lives lost to smoking, thereby showing the potential of tobacco control policies specifically in a middle-income country. Additional improvements can be realised through higher taxes, stronger clean air policies, comprehensive cessation treatment policies, and targeted media campaigns.

Autolysis of Pacific white shrimp (Litopenaeus vannamei) meat: characterization and the effects of protein additives

Autolytic activity of Pacific white shrimp (Litopenaeus vannamei) mince in the absence and in the presence of 2.5%NaCl was investigated. Pacific white shrimp mince exhibited the maximum autolytic activity at 35 and 40 degrees C in the absence and in the presence of 2.5%NaCl, respectively, as evidenced by the highest TCA-soluble peptide content and the greatest disappearance of myosin heavy chain (MHC). The autolysis was more pronounced in the acidic pH values, followed by alkaline pH ranges. Pepstatin A showed the highest inhibition toward autolysis in the acidic condition, revealing that aspartic proteinase was dominant in shrimp muscle. Nevertheless, soybean trypsin inhibitor effectively inhibited the autolysis at neutral and alkaline pH values, suggesting that serine proteinase was present in shrimp mince but contributed to autolysis at a lower extent in shrimp meat. Autolysis in shrimp meat could be inhibited partially by all protein additives, including bovine plasma protein (BPP), egg white (EW), and whey protein concentrate (WPC). The inhibition of autolysis increased when the level of protein additives increased with the concomitant increase in band intensity of MHC retained. WPC and BPP in the range of 2% to 3% exhibited the highest inhibition toward autolysis of shrimp mince.

Microstructure and thermal characteristics of Thai indigenous and broiler chicken muscles

The microstructure and thermal characteristics of Thai indigenous (Gallus domesticus) and broiler chicken (commercial line CP707) biceps femoris and pectoralis muscles were determined. Perimysium thicknesses were 14.2 microm for biceps femoris muscle and 7.10 microm for pectoralis muscle of indigenous chicken muscles, thicker than those of broiler muscles, which were 9.93 microm for biceps femoris muscle and 3.87 microm for pectoralis muscle (P < 0.05). Five endothermic peaks with peak transition temperatures (Tp) of 54.9, 61.7, 65.4, 70.6, and 76.1 degrees C were obtained for broiler pectoralis muscle, whereas only 3 endothermic peaks (Tp of 56.6, 62.6, and 74.9 degrees C) were obtained for broiler biceps femoris muscle. Thai indigenous biceps femoris and pectoralis muscles had endothermic peaks with Tp ranges of 53.5 to 54.8, 60.7 to 61.9, and 75.9 to 76.9 degrees C. The fiber diameters of Thai indigenous chicken muscles were greater (P < 0.05) than those of the broiler, 31.7 vs. 20.4 microm for biceps femoris muscle and 28.9 vs. 26.6 microm for pectoralis muscle, respectively. After cooking at 80 degrees C for 10 min, the fiber diameter of indigenous chicken muscles significantly decreased while those of the broiler significantly increased. The mean of sarcomere lengths of the raw muscles ranged from 1.56 to 1.64 microm and decreased to 0.92 to 1.32 microm (P < 0.001) for broiler muscles and 1.22 to 1.35 microm (P < 0.001) for indigenous chicken muscles after cooking. The perimysium and endomysium of broiler muscles melted after cooking at 80 degrees C, however, only slight disintegration was observed in these tissues in the indigenous chicken muscles.

Composition, Color, and Texture of Thai Indigenous and Broiler Chicken Muscles

Chemical compositions and physical properties of mixed-sex Thai indigenous (Gallus domesticus) and broiler (commercial breed, CP707) chicken biceps femoris and pectoralis muscles were determined. Indigenous chicken muscles contained higher protein contents but lower fat and ash contents compared to broiler muscles (P < 0.001). The amino acid profile of the indigenous chicken muscles was similar to that of the broiler muscles except they were slightly richer in glutamic acid (P < 0.05). The indigenous chicken muscles contained more saturated and less polyunsaturated fatty acids than the broiler muscles. There were no differences in the monounsaturated fatty acid contents between the breeds. The total collagen contents of indigenous pectoralis and biceps femoris muscles were 5.09 and 12.85 mg/g, respectively, which were higher than those found in broiler pectoralis (3.86 mg/g) and biceps femoris muscles (8.70 mg/g) (P < 0.001). Soluble collagen contents were lower for indigenous pectoralis and biceps femoris muscles, 22.16 vs. 31.38% and 26.06 vs. 33.87%, respectively. The CIE system values of lightness (L*), redness (a*), and yellowness (b*) of indigenous chicken muscles were higher than those of broiler muscles. The shear values of indigenous chicken muscles either raw or cooked were higher than those of broiler muscles (P < 0.05). After cooking, the shear values decreased for broiler biceps femoris and pectoralis muscles (P < 0.05), whereas no change was observed for indigenous chicken biceps femoris muscle (P > 0.05). Shear values increased for indigenous chicken pectoralis muscle (P < 0.05).