3D printing of tissue engineering scaffolds: a focus on vascular regeneration.

Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine. Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood vessels. Scaffold-based tissue engineering approaches are effective methods to form new blood vessel tissues. The demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue engineering. Recent advances in 3D printing have facilitated fabrication of vascular scaffolds, contributing to broad prospects for tissue vascularization. This review presents state of the art on modeling methods, print materials and preparation processes for fabrication of vascular scaffolds, and discusses the advantages and application fields of each method. Specially, significance and importance of scaffold-based tissue engineering for vascular regeneration are emphasized. Print materials and preparation processes are discussed in detail. And a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting, electrospinning, and Lego-like construction. And related studies are exemplified. Transformation of vascular scaffolds to clinical application is discussed. Also, four trends of 3D printing of tissue engineering vascular scaffolds are presented, including machine learning, near-infrared photopolymerization, 4D printing, and combination of self-assembly and 3D printing-based methods.

Bioscaffolds embedded with regulatory modules for cell growth and tissue formation: A review.

The demand for artificial organs has greatly increased because of various aging-associated diseases and the wide need for organ transplants. A recent trend in tissue engineering is the precise reconstruction of tissues by the growth of cells adhering to bioscaffolds, which are three-dimensional (3D) structures that guide tissue and organ formation. Bioscaffolds used to fabricate bionic tissues should be able to not only guide cell growth but also regulate cell behaviors. Common regulation methods include biophysical and biochemical stimulations. Biophysical stimulation cues include matrix hardness, external stress and strain, surface topology, and electromagnetic field and concentration, whereas biochemical stimulation cues include growth factors, proteins, kinases, and magnetic nanoparticles. This review discusses bioink preparation, 3D bioprinting (including extrusion-based, inkjet, and ultraviolet-assisted 3D bioprinting), and regulation of cell behaviors. In particular, it provides an overview of state-of-the-art methods and devices for regulating cell growth and tissue formation and the effects of biophysical and biochemical stimulations on cell behaviors. In addition, the fabrication of bioscaffolds embedded with regulatory modules for biomimetic tissue preparation is explained. Finally, challenges in cell growth regulation and future research directions are presented.

Effect of glazing and rosemary (Rosmarinus officinalis) extract on preservation of mud shrimp (Solenocera melantho) during frozen storage.

In this study, glazing with water and rosemary (Rosmarinus officinalis) extract were applied on frozen mud shrimp (Solenocera melantho) and stored at -20 °C for 24 weeks. Quality loss and protein and lipid changes of shrimp were evaluated by total volatile basis nitrogen (TVB-N), drip loss, moisture distribution, sulfhydryl content (SH), disulfide bond, intrinsic fluorescence intensity, lipid content, free fatty acids (FFA), peroxide value (PV), fluorescent compounds and sensory characteristics. Results showed that unglazed mud shrimp exhibited significant quality decline after 16 weeks of frozen storage. Glazing treatment significantly reduced quality loss, protein degradation, and lipid oxidative damage of shrimp during the 24 weeks of frozen storage, compared to the unglazed control sample. Glazing with rosemary extract was more effective in controlling quality changes in frozen mud shrimp with lower TVB-N, drip loss, PV, FFA and higher lipid content and sensory scores.

Differential proteomic analysis to identify proteins associated with quality traits of frozen mud shrimp (Solenocera melantho) using an iTRAQ-based strategy.

An iTRAQ-based strategy was applied to investigate proteome changes in mud shrimp during long-term frozen storage under different conditions. A total of 226 proteins was identified as differential abundance proteins (DAPs) in mud shrimp from two frozen treatment groups (-20 °C and -40 °C) compared with the fresh control group. The proteome changes in mud shrimp muscle stored under -20 °C was much greater than that under -40 °C. Correlation analysis between DAPs and quality traits of mud shrimp muscle showed that 12 proteins were correlated closely with color (L∗, a∗, and b∗ value) and texture (hardness, elasticity, and chewiness). Bioinformatic analysis revealed that most of these proteins were involved in protein structure, metabolic enzymes, and protein turnover. Among them, several proteins might be potential protein markers for color, and some proteins are good candidate predictors for textural properties of mud shrimp muscle.

Changes in Biogenic Amines and ATP-Related Compounds and Their Relation to Other Quality Changes in Common Carp (Cyprinus carpio var. Jian) Stored at 20 and 0°C.

Biogenic amines, ATP-related compounds, sensory attributes, total volatile basic nitrogen, microbial flora (total viable bacteria, Pseudomonas, Aeromonas, and H2S-producing bacteria), and free amino acids were determined in common carp (Cyprinus carpio var. Jian) stored at 20 and 0°C. Pseudomonas and H2S-producing bacteria became the dominant bacteria in carp stored at 20 and 0°C, whereas Aeromonas rapidly increased only in carp stored at 0°C. Inosine monophosphate, which is responsible for flavor and freshness, increased to a maximum of 2.37 l mol/g after 12 h at 20°C and to 4.72 l mol/g after 3 days at 0°C. Putrescine and cadaverine were the dominant amines in carp and their concentrations were significantly correlated (P < 0.05) with total volatile basic nitrogen and sensory scores in all samples during the storage. Significant correlations also were observed between histamine and total volatile basic nitrogen and sensory scores only in samples stored at 20°C. Arginine decreased while putrescine increased in all samples. A significant decrease (P < 0.05) in histidine was observed after 24 h of storage, which coincided with an increase in histamine after 36 h in samples stored at 20°C. Hypoxanthine concentrations were significantly correlated with the microbial species (P < 0.01) and sensory scores (P < 0.05) and seems to be a reliable marker for quality of carp fillets stored at 20 and 0°C.

Seasonal variations of fatty acid profile in different tissues of farmed bighead carp (Aristichthys nobilis).

Bighead carp (Aristichthys nobilis) is one of the major farmed species of freshwater fish in China. Byproduct volume of bighead carp is significant at up to 60 % of whole fish weight. A better understanding of the nutritional composition is needed to optimize the use of these raw materials. The objective of this research was to characterize seasonal variations of fatty acid profile in different tissues (heads, bones, skin, scales, viscera, muscle and fins) of farmed bighead carp. The fatty acid composition of farmed bighead carp varied significantly with seasons and tissues. The highest lipid content was determined in viscera while the highest EPA and DHA composition were observed in muscle compared to the other tissues. Significantly higher ΣEPA+DHA (%) was recorded in all tissues in summer (June) when compared with those of the other three seasons (p < 0.05). The n-3/n-6 fatty acid ratios in summer ranged from 3.38 to 3.69, nearly three times the ratios of the other three seasons. The results indicated that farmed bighead carp caught in summer could better balance the n-3 PUFA needs of consumers. The byproducts of bighead carp can be utilized for the production of fish oil.

Effects of different concentrations of salt and sugar on biogenic amines and quality changes of carp (Cyprinus carpio) during chilled storage.

BACKGROUND: Biogenic amines have gained a great deal of attention due to their toxic potential in humans. Carp is one of the most important freshwater fish species in China. Salt and sugar are capable of preserving food. There is a limited amount of information on the changes of biogenic amines in freshwater fish influenced by salt and sugar. This study aimed to detect the changes in biogenic amines, sensory attributes, total volatile basic nitrogen (TVB-N) and total viable counts (TVC) of carp influenced by different concentrations of salt and sugar stored at 4 °C. RESULTS: TVB-N and TVC increased with storage time, which was in accordance with the changes of sensory scores. The eight biogenic amines were detected in fresh carp. Putrescine and cadaverine were the main biogenic amines found in carp fillets stored at 4 °C; they had a significant (P < 0.05) correlation with TVB-N. CONCLUSION: Salt processing was found to inhibit the increase of TVB-N, TVC, putrescine and cadaverine in carp. High salt concentration had a positive effect on extending the shelf-life of the carp, compared to low salt concentration.

Changes in physiochemical properties of water-soluble proteins from crucian carp (Carassius auratus) during heat treatment.

In order to understand physicochemical properties of water-soluble proteins obtained from crucian carp, turbidity, total sulfhydryl content, hydrophobicity and SDS-PAGE of crucian carp water-soluble proteins during heat treatment were investigated. Turbidity remained unchanged up to 44°C and considerably increased from 46°C to 54°C, one peak of increase rate was found at 50°C; total SH content decreased rapidly when heated from 50°C to 55°C; hydrophobicity increased sharply when heated up to 45°C, indicating the conformation of water-soluble proteins from crucian carp began to unfold and expose the buried nonpolar amino acids at temperatures above 45°C; analysis of SDS-PAGE indicating the formation of disulfide linkage of creatine kinase and glyceraldehy-3-phosphate dehydrogenase when the temperature reached 65°C and 80°C, respectively.

Effects of different freezing treatments on the biogenic amine and quality changes of bighead carp (Aristichthys nobilis) heads during ice storage.

The effects of different freezing treatments on the quality changes of bighead carp heads were evaluated in terms of pH value, TBARS, TVB-N, K-value, biogenic amine, total aerobic counts (TACs), drip loss, cooking loss and electrical conductivity (EC) during ice storage. Fish heads were stored at -40°C (T1), -40°C for 12h and then -18°C (T2), -18°C (T3) for 3months prior to ice storage. No significant differences were observed among T1, T2 and T3 for drip loss, cooking loss and EC (p>0.05). T2 showed lower TACs, pH value, TBARS and TVB-N than T3 did. Significant lower value of spermine and spermidine were observed in T1, T2 and T3 than those of control group (fresh) from 9th to 18th day (p<0.05). Drip loss was significantly correlated with TBARS, pH value, TVB-N, and TACs in groups T1, T2 and T3 (p<0.05).

Formation of biogenic amines in crucian carp (Carassius auratus) during storage in ice and at 4°C.

The formation of eight biogenic amines (BAs), total volatile base nitrogen (TVB-N), aerobic plate counts (APC), and sensory evaluation in crucian carp (Carassius auratus) during storage in ice and at 4°C were investigated. The sum of contents of all eight biogenic amines (SBA) in crucian carp increased from 49.82 to 197.09 mg/kg on day 36 when stored in ice and from 49.82 to 219.35 mg/kg on day 24 when stored at 4°C. TVB-N content increased with storage time; good relationships between TVB-N content and SBA were observed during storage in ice and at 4°C (R(2) = 0.95 and 0.93, respectively). APC of all samples significantly (P < 0.05) increased with storage time in the first 12 days and toward the end of the storage period, there were only minor changes; good relationships between APC and SBA were observed during storage in ice and at 4°C (R(2) = 0.96 and 0.58, respectively). According to sensory evaluation results, the crucian carp became unacceptable on days 24 and 16 during storage in ice and at 4°C, respectively. Putrescine and tyramine contents could be good quality evaluation indices for crucian carp during storage.

Changes in biogenic amines of silver carp (Hypophthalmichthys molitrix) fillets stored at different temperatures and their relation to total volatile base nitrogen, microbiological and sensory score.

BACKGROUND: Biogenic amines have received considerable attention owing to their undesirable effects in humans. There are few studies of changes in biogenic amine contents related to freshwater fish. Silver carp is an important freshwater fish species in China. This study aimed to investigate the changes in biogenic amines and their relation to total volatile base nitrogen (TVB-N), microbiological and sensory score of silver carp fillets stored at 0, 3 and 15 °C. RESULTS: The total biogenic amine contents of all silver carp fillets (regardless of storage time and temperature) ranged from 13.05 to 318.10 mg kg(-1). Putrescine and histamine were the main biogenic amines in silver carp fillets during storage. Cadaverine was only detected after 12 days at 3 °C and after 2 days at 15 °C. Spermidine and spermine contents increased during the early storage period and then slightly decreased. CONCLUSION: Low temperature could control the quality of silver carp fillets by inhibiting the contents of biogenic amines. Putrescine showed significant correlation with TVB-N, total aerobic content, sensory score, tryptamine and phenylethylamine. Putrescine was a good quality marker of silver carp fillets in the cold chain.

Antioxidant activities and functional properties of grass carp (Ctenopharyngodon idellus) protein hydrolysates.

BACKGROUND: Grass carp, with an annual production exceeding 4 × 10(6) t in China in 2009, has not been developed into a high-value product. In this study the antioxidant activities and functional properties of grass carp protein hydrolysates prepared with Alcalase 2.4L (HA) and papain (HP) were investigated. The hydrolysate with strongest radical-scavenging activity and reducing power was assessed further for changes in its antioxidant activity during simulated gastrointestinal digestion. RESULTS: As the degree of hydrolysis (DH) increased, the metal-chelating activity of both HA and HP increased while their reducing power and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(•) )-scavenging activity decreased (P < 0.05). At the same DH, HP possessed higher DPPH(•) -scavenging activity and reducing power than HA (P < 0.05). The metal-chelating activity of HP with 10% DH was significantly increased after in vitro gastrointestinal metabolism (P < 0.05). Regarding their functional properties, all hydrolysates were more than 81% soluble over a wide range of pH (3-8). At the same DH, HP showed higher emulsion activity index but lower solubility and foaming capacity than HA. CONCLUSION: Grass carp protein hydrolysates showed high solubility over a wide pH range and could be used as natural antioxidants in food systems.

Biochemical, sensory and microbiological attributes of bream (Megalobrama amblycephala) during partial freezing and chilled storage.

BACKGROUND: Bream is one of the main farmed freshwater fish species in China. This study aimed to examine the nucleotide degradation of bream during partial freezing and chilled storage and to assess the possible usefulness of nucleotide ratios (K, Ki, H, P, Fr and G values) as freshness indices in comparison with sensory assessment and total viable counts. RESULTS: Total viable counts were 5.74 and 4.66 log(colony-forming units g(-1)) on the day of sensory rejection under chilled storage and partial freezing storage respectively. The inosine 5-monophosphate decrease and inosine increase were faster in chilled storage than in partial freezing storage. Hypoxanthine levels increased continuously with time under both storage regimes. Among the nucleotide ratios, the K, Ki, P, G and Fr values were superior to the H value and provided useful freshness indicators for both storage conditions. CONCLUSION: Bream in chilled storage were sensorially acceptable only up to 10 days, compared with 33 days for bream in partial freezing storage. Partial freezing delayed the nucleotide degradation of bream.

Antioxidant activity of hydrolysates and peptide fractions derived from porcine hemoglobin.

Porcine hemoglobin hydrolysate (PHH) was prepared with 6 different proteases (flavourzyme, papain, A.S.1398, alcalase, pepsin and trypsin). There was no correlation between extent of hydrolysis and antioxidant activity (p > 0.05). The peptic hydrolysate prepared at 60 min possessed the strongest antioxidant potential (67.0 ± 1.84%) among different hydrolysates, which was fractionated into 4 major types by ultrafiltration membranes with different molecular weight cut-off (MWCO), PHH-I (Mw > 10 kDa), PHH-II (Mw = 5-10 kDa), PHH-III (Mw = 3-5 kDa) and PHH-IV (Mw < 3 kDa). PHH-IV possessed higher inhibitory effects of lipid peroxidation and scavenging effects on superoxide radical compared with larger MW fractions. Four fractions possessed the scavenging effects on 1, 1-diphenyl-2-picrylhy-drazyl (DPPH) and hydroxyl radicals in the order PHH-IV > PHH-I > PHH-III > PHH-II. MW of the 2 major peptide fractions from PHH-IV was located at 2476 Da (F1) and 1042 Da (F2), respectively. PHH-IV could be utilized to develop physiologically functional foods or therapy drugs.

[The effects of endoscopic nasal surgery on the function of eustachian tube].

OBJECTIVE: To observe the effects of endoscopic nasal surgery on the function of eustachian tube. METHOD: The tympanometric pressure, static compliance and gradient of tympanogram were measured for sinuses and turbinate group (10 cases) and nasal septum group (10 cases) at 1, 3, 5 and 10 days after operation by using audiometer acoustic impedance. RESULT: The peak pressure of tympanogram of two groups were droped obviously 1-3 days after operation. In sinuses and turbinate group, it droped from -85.5 dapa to -148.0 dapa (at 1 day) and -139.0 dapa at 3 days, compared to the pre-operation, the differences were significantly (P < 0.01). In nasal septum group, it droped from -51.0 dapa to -111.5 dapa at 1 day and -96.0 dapa at 3 days, compared to the pre-operation, the differences were also significantly (P < 0.01). The level of static compliance, gradient were no significantly difference between before and after operation (P > 0.05). CONCLUSION: The eustachian tube of patients of two groups were blocked at the early stage of post-operation. The treatment of active anti-infection, promptly cleaning of nasal cavity, relexing the pressure of nasal cavity as soon as possible, all of this can reduce the effect of operation on the function of eustachian tube.