Impact of Processing Methods on the Distribution of Mineral Elements in Goat Milk Fractions.

Milk and dairy products are excellent sources of mineral elements, including Ca, P, Mg, Na, K and Zn. The purpose of this study was to determine the effect of non-thermal (homogenization) and thermal (heat treatment) treatments on the distribution of mineral elements in 4 milk fractions: fat, casein, whey protein, and aqueous phase. The study results revealed that the distribution of mineral elements (such as Mg and Fe) in fat fractions is extremely low, while significant mineral elements such as Ca, Zn, Fe, and Cu are mostly dispersed in casein fractions. For non-treated goat milk, Mo is the only element identified in the whey protein fraction, while K and Na are mostly found in the aqueous phase. Mineral element concentrations in fat (K, Zn, etc.) and casein fraction (Fe, Mo, etc.) increased dramatically after homogenization. Homogenization greatly decreased the concentration of mineral elements in the whey protein fraction (Ca, Na, etc.) and aqueous phase (Fe, Cu, etc.). After heat treatment, the element content in the fat fraction and casein fraction increased greatly when compared with raw milk, such as Cu and Mg in the fat fraction, Na and Cu in the whey protein fraction, the concentration of components such as Mg and Na in casein fraction increased considerably. On the other hand, after homogenization, Zn in the aqueous phase decreased substantially, whereas Fe increased significantly. Therefore, both homogenization and heat treatment have an effect on the mineral element distribution in goat milk fractions.

Effect of lactation on the distribution of mineral elements in goat milk.

The distribution of mineral elements in milk is crucial for their absorption and utilization, however, there has been limited attention given to the status of mineral elements in goat milk. In this study, goat milk was collected at 4 lactation periods (1-3, 90, 150, 240 d) and separated into 4 fractions (fat, casein, whey, and aqueous phase). The concentrations of Mg, Ca, Na, K, Zn, Fe, Cu, Mn, Co, Ni, Mo, and Cr in 4 fractions were analyzed using an inductively coupled plasma emission spectrometer. Our findings reveal that Ca, Zn, Fe, Cu, Mn, and Cr exhibit the highest levels in casein, while Mo demonstrates the highest content in whey. Additionally, Mg, Na, K, and Ni display the highest concentrations in the aqueous phase. Specifically, the contents of Ca, Cu and Fe in casein decrease from 1-3 to 150 d of lactation but increase from 150 to 240 d of lactation. Furthermore, the content of Mg in the aqueous phase decreases from 1-3 to 90 d of lactation but increases from 90 to 240 d of lactation. The content of Na and K in the aqueous phase decreases from 1-3 to 150 d of lactation. Notably, the content of Mo in whey increases from 1-3 to 150 d of lactation and decreases from 150 to 240 d. Our research contributes to the advancement of understanding the bioavailability of mineral elements in goat milk.

Identification markers of goat milk adulterated with bovine milk based on proteomics and metabolomics.

This study investigated the differences in proteins and metabolites from goat and bovine milk, and their mixtures, using data-independent-acquisition-based proteomics and metabolomics methods. In the skim milk, relative abundances of secretoglobin family 1D member (SCGB1D), polymeric immunoglobulin receptor, and glycosylation-dependent cell adhesion molecule 1 were increased, with an increase in the amount of 1-100 % bovine milk and served as markers at the 1 % adulteration level. In whey samples, ß-lactoglobulin and α-2-HS-glycoprotein could be used to detect adulteration at the 0.1 % adulteration level, and SCGB1D and zinc-alpha-2-glycoprotein at the 1 % level. The metabolites of uric acid and N-formylkynurenine could be used to detect bovine milk at adulteration levels as low as 1 % based on variable importance at a projection value of > 1.0 and P-value of < 0.05. Our findings suggest novel markers of SCGB1D, uric acid, and N-formylkynurenine that can help to facilitate assessments of goat milk authenticity.

Probiotics Alleviate Food Protein Allergy in Mice by Activating TLR4 Signaling Pathway.

SCOPE: Food allergy has become a world recognized public health problem due to its versatility and lack of efficacious methods for its treatment. Probiotics supplement is a potential way to prevent food allergy. METHODS AND RESULTS: In this study, potential strains are screen out by peripheral blood mononuclear cells (PBMCs), and their abilities of alleviating food allergy are examined using a mouse model induced by ovalbumin (OVA). The results show that six strains increase ratio of interferon-γ (IFN-γ)/interleukin (IL)-4 secreted by PBMCs with good abilities in intestinal adhesion and gastrointestinal tolerance. Oral administration of Bifidobacterium animalis KV9 (KV9) and Lactobacillus vaginalis FN3 (FN3) attenuates allergic responses in allergy mice, including allergic symptoms, mast cells aggregation and activity, serum OVA-special-immunoglobulins E (OVA-sIgE) production. KV9 and FN3 upregulate the production of IFN-γ/IL-4 in splenocytes, increase the genes and proteins expression of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (Myd88) and interferon regulatory factor (IRF)-1 in allergic mice spleen, and decrease the IRF-4. CONCLUSION: The study demonstrates that KV9 and FN3 possess anti-allergic activities via activation of TLR4 pathway and modulating the expression of IRF-1 and IRF-4 which leads to T helper type 1 (Th1)/T helper type 2 (Th2) cell immunology balance.

Changes in milk fat globule physical properties and milk fatty acid composition throughout the lactation cycle of Laoshan goat.

The objective of this study was to investigate the effect of lactation stage on the physical properties of milk fat globules (MFGs) and profiles of milk fatty acids (FAs) of milk from Laoshan dairy goats. Goat colostrum and milk samples were collected on days 1, 3, 30, 90, 150, and 240 postpartum. Milk fat content was found to significantly decrease during the first 90 d of lactation and increase thereafter as lactation progressed (P < 0.01). Average area particle size and volume particle size of MFGs showed trends similar to those of the milk fat content of goat milk with the extension of lactation, and the lowest levels were 2.39 µm and 3.97 µm on day 90, respectively (P < 0.01). The zeta-potential of MFGs significantly increased before 30 d of lactation, with a slight drop on day 90. It increased thereafter and tended to stabilize in the late stages of lactation (P < 0.01). The content of several saturated fatty acids (SFAs) (C10:0-C16:0) in early lactation, especially in colostrum, was lower than that in other stages of lactation (P < 0.05). Branched-chain fatty acids of the iso and anteiso series, including C13:0 anteiso, C15:0 anteiso, and C15:0 iso, were observed at high contents in mid-lactation goat milk (P < 0.01). As lactation progressed (3 d to 240 d), the content of SFAs significantly increased (P < 0.01), while the content of monounsaturated fatty acids and polyunsaturated fatty acids significantly decreased (P < 0.05). Furthermore, the content of C18:0 significantly increased during the first 30 d of lactation and decreased thereafter as lactation progressed (P < 0.01). Our results indicated that lactation stage has a pronounced effect on the physical properties of MFGs and the FA profiles of goat milk.

The composition and physical properties of milk fat affect the quality and sensory properties of dairy products. However, changes in the physical properties of milk fat globules (MFGs) and profiles of milk fatty acids (FAs) of goat milk throughout the lactation period remain unclear. In the current study, we found that milk fat content and particle size of goat MFG decreased significantly during 90 d of lactation and increased thereafter as lactation progressed. The content of saturated FAs significantly increased, while that of monounsaturated FAs and polyunsaturated FAs significantly decreased from colostrum to late-lactation milk. The characteristics of goat MFGs and milk FAs were affected by the lactation period, which may provide valuable insights into the utilization of MFGs from dairy goats.

Identification of mare milk adulteration with cow milk by liquid chromatography-high resolution mass spectrometry based on proteomics and metabolomics approaches.

Mare milk(MM)production is lower than that of cow milk (CM), making it a premium product. Unfortunately, sellers adulterate MM with cheap CM to unscrupulously gain more profits. This study aimed to analyze MM adulteration with CM using proteomics and metabolomics. Using univariate and multivariate statistical analysis, the relative abundances of certain proteins of caseins and secretoglobin family 1D member were found to be higher with a higher CM admixture percentage. In addition, several metabolites, such as orotic and 4-aminonicotinic acids, increased in the mare-cow milk mixture with an increased CM percentage. Accordingly, these proteins and metabolites distinguished MM adulterated with CM at levels as low as 1 %.These findings can serve as the basis for clarifying the differences at the proteome and metabolome in milk from minor dairy animals and ensure milk authenticity.

Bifidobacterium animalis KV9 and Lactobacillus vaginalis FN3 alleviated ß-lactoglobulin-induced allergy by modulating dendritic cells in mice.

Food allergy is a serious public health problem because of its high incidence and risk. Probiotics can induce immune regulation in patients with allergic diseases, but its mechanism is not fully clear. In this paper, ß-lactoglobulin (ß-LG)-sensitized mice were used as models to explore the mechanism of Bifidobacterium animalis KV9 (KV9) and Lactobacillus vaginalis FN3 (FN3) on reducing allergic reactions and regulating immune cell function. The results showed that oral administration of KV9 and FN3 significantly reduced the scores of allergic symptoms, hypothermia symptoms, and serum levels of ß-LG-specific immunoglobulins E (ß-LG-sIgE), histamine, and mast cell protease in allergic mice. Flow cytometry analysis of intestinal dendritic cells (DCs) showed that the proportion of CD11c+major histocompatibility complex (MHC)-II+DCs, CD11c+CD80+DCs, and CD11c+ CD86+DCs increased after KV9 and FN3 intervention, indicating that the strains induced immature DCs and decreased the antigen-presenting capacity of DCs. Meanwhile, the toll-like receptor 4 (TLR4)-NF-κB signaling pathway was activated in DCs. The secretion of interleukin-12 (IL-12) was significantly increased, while interleukin-4 (IL-4) was decreased by DCs after KV9 and FN3 intervention, indicating that DCs have the potential to promote T-cell differentiation into T helper type 1 (Th1) cells. Furthermore, the proportion of CD3+CD8-IFN-γ+ T cells in the spleen increased, while CD3+CD8-IL-4+T cells decreased after oral administration of KV9 and FN3, correcting the T helper type 2 (Th2)-skewed immune responses. These results indicate that KV9 and FN3 reduce ß-LG-induced allergic symptoms in mice, and suggest that the two potential probiotics might be used as an alternative therapeutic agent for mitigating food allergy.

Research on new treatment mode of radiotherapy based on pseudo-medical images.

BACKGROUND AND OBJECTIVE: Multi-modal medical images with multiple feature information are beneficial for radiotherapy. A new radiotherapy treatment mode based on triangle generative adversarial network (TGAN) model was proposed to synthesize pseudo-medical images between multi-modal datasets. METHODS: CBCT, MRI and CT images of 80 patients with nasopharyngeal carcinoma were selected. The TGAN model based on multi-scale discriminant network was used for data training between different image domains. The generator of the TGAN model refers to cGAN and CycleGAN, and only one generation network can establish the non-linear mapping relationship between multiple image domains. The discriminator used multi-scale discrimination network to guide the generator to synthesize pseudo-medical images that are similar to real images from both shallow and deep aspects. The accuracy of pseudo-medical images was verified in anatomy and dosimetry. RESULTS: In the three synthetic directions, namely, CBCT â†’ CT, CBCT â†’ MRI, and MRI â†’ CT, significant differences (p < 0.05) in the three-fold-cross validation results on PSNR and SSIM metrics between the pseudo-medical images obtained based on TGAN and the real images. In the testing stage, for TGAN, the MAE metric results in the three synthesis directions (CBCT â†’ CT, CBCT â†’ MRI, and MRI â†’ CT) were presented as mean (standard deviation), which were 68.67 (5.83), 83.14 (8.48), and 79.96 (7.59), and the NMI metric results were 0.8643 (0.0253), 0.8051 (0.0268), and 0.8146 (0.0267) respectively. In terms of dose verification, the differences in dose distribution between the pseudo-CT obtained by TGAN and the real CT were minimal. The H values of the measurement results of dose uncertainty in PGTV, PGTVnd, PTV1, and PTV2 were 42.510, 43.121, 17.054, and 7.795, respectively (P < 0.05). The differences were statistically significant. The gamma pass rate (2%/2 mm) of pseudo-CT obtained by the new model was 94.94% (0.73%), and the numerical results were better than those of the three other comparison models. CONCLUSIONS: The pseudo-medical images acquired based on TGAN were close to the real images in anatomy and dosimetry. The pseudo-medical images synthesized by the TGAN model have good application prospects in clinical adaptive radiotherapy.

Synthesis of pseudo-CT images from pelvic MRI images based on an MD-CycleGAN model for radiotherapy.

Objective.A multi-discriminator-based cycle generative adversarial network (MD-CycleGAN) model is proposed to synthesize higher-quality pseudo-CT from MRI images.Approach.MRI and CT images obtained at the simulation stage with cervical cancer were selected to train the model. The generator adopted DenseNet as the main architecture. The local and global discriminators based on a convolutional neural network jointly discriminated the authenticity of the input image data. In the testing phase, the model was verified by a fourfold cross-validation method. In the prediction stage, the data were selected to evaluate the accuracy of the pseudo-CT in anatomy and dosimetry, and they were compared with the pseudo-CT synthesized by GAN with the generator based on the architectures of ResNet, sUNet, and FCN.Main results.There are significant differences (P < 0.05) in the fourfold cross-validation results on the peak signal-to-noise ratio and structural similarity index metrics between the pseudo-CT obtained based on MD-CycleGAN and the ground truth CT (CTgt). The pseudo-CT synthesized by MD-CycleGAN had closer anatomical information to the CTgtwith a root mean square error of 47.83 ± 2.92 HU, a normalized mutual information value of 0.9014 ± 0.0212, and a mean absolute error value of 46.79 ± 2.76 HU. The differences in dose distribution between the pseudo-CT obtained by MD-CycleGAN and the CTgtwere minimal. The mean absolute dose errors of Dosemax, Dosemin, and Dosemeanbased on the planning target volume were used to evaluate the dose uncertainty of the four pseudo-CT. The u-values of the Wilcoxon test were 55.407, 41.82, and 56.208, and the differences were statistically significant. The 2%/2 mm-based gamma pass rate (%) of the proposed method was 95.45 ± 1.91, and the comparison methods (ResNet_GAN, sUnet_GAN, and FCN_GAN) were 93.33 ± 1.20, 89.64 ± 1.63, and 87.31 ± 1.94, respectively.Significance.The pseudo-CT images obtained based on MD-CycleGAN have higher imaging quality and are closer to the CTgtin terms of anatomy and dosimetry than other GAN models.

Distribution and variation in proteins of casein micellar fractions response to heat-treatment from five dairy species.

Casein micelles (CMs) contribute to the physicochemical properties and stability of milk. However, how the proteome of CMs changes following heat treatment has not been elucidated. Here, changes in the proteins of CMs in samples of Holstein, buffalo, yak, goat, and camel milk following heat treatment were investigated using a LC-MS/MS approach. According to the hierarchical clustering results, Holstein, yak, and buffalo milk samples had similar CMs protein components, followed by goat and camel milk samples. Changes in lipoprotein lipase and α-lactalbumin in CMs were dependent on the intensity of heat treatment and were similar among the studied species, whereas changes in κ-casein, lactoferrin, and apolipoprotein A-I differed among different types of milk. These results provide information on the distribution and variations of the proteomes of CMs following heat treatment, which will assist in the identification of proteins that are dissociated and attached to CMs from different dairy species during heat treatment.

Prevalence, Drug Resistance, and Virulence Genes of Potential Pathogenic Bacteria in Pasteurized Milk of Chinese Fresh Milk Bar.

Fresh Milk Bar (FMB), an emerging dairy retail franchise, is used to instantly produce and sell pasteurized milk and other dairy products in China. However, the quality and safety of pasteurized milk in FMB have received little attention. The objective of this study was to investigate the prevalence, antimicrobial resistance, and virulence genes of Escherichia coli, Staphylococcus aureus, and Streptococcus in 205 pasteurized milk samples collected from FMBs in China. Four (2.0%) isolates of E. coli, seven (3.4%) isolates of S. aureus, and three (1.5%) isolates of Streptococcus agalactiae were isolated and identified. The E. coli isolates were resistant to amikacin (100%), streptomycin (50%), and tetracycline (50%). Their detected resistance genes include aac(3)-III (75%), blaTEM (25%), aadA (25%), aac(3)-II (25%), catI (25%), and qnrB (25%). The S. aureus isolates were mainly resistant to penicillin G (71.4%), trimethoprim-sulfamethoxazole (71.4%), kanamycin (57.1%), gentamicin (57.1%), amikacin (57.1%), and clindamycin (57.1%). blaZ (42.9%), mecA (28.6%), ermB (14.3%), and ermC (14.3%) were detected as their resistance genes. The Streptococcus strains were mainly resistant to tetracycline (66.7%) and contained the resistance genes pbp2b (33.3%) and tetM (33.3%). The virulence genes eae and stx2 were only found in one E. coli strain (25%), sec was detected in two S. aureus strains (28.6%), and bca was detected in one S. agalactiae strain (33.3%). The results of this study indicate that bacteria with drug resistance and virulence genes isolated from the pasteurized milk of FMB are a potential risk to consumers' health.

Research on obtaining pseudo CT images based on stacked generative adversarial network.

BACKGROUND: To investigate the feasibility of using a stacked generative adversarial network (sGAN) to synthesize pseudo computed tomography (CT) images based on ultrasound (US) images. METHODS: The pre-radiotherapy US and CT images of 75 patients with cervical cancer were selected for the training set of pseudo-image synthesis. In the first stage, labeled US images were used as the first conditional GAN input to obtain low-resolution pseudo CT images, and in the second stage, a super-resolution reconstruction GAN was used. The pseudo CT image obtained in the first stage was used as an input, following which a high-resolution pseudo CT image with clear texture and accurate grayscale information was obtained. Five cross validation tests were performed to verify our model. The mean absolute error (MAE) was used to compare each pseudo CT with the same patient's real CT image. Also, another 10 cases of patients with cervical cancer, before radiotherapy, were selected for testing, and the pseudo CT image obtained using the neural style transfer (NSF) and CycleGAN methods were compared with that obtained using the sGAN method proposed in this study. Finally, the dosimetric accuracy of pseudo CT images was verified by phantom experiments. RESULTS: The MAE metric values between the pseudo CT obtained based on sGAN, and the real CT in five-fold cross validation are 66.82±1.59 HU, 66.36±1.85 HU, 67.26±2.37 HU, 66.34±1.75 HU, and 67.22±1.30 HU, respectively. The results of the metrics, namely, normalized mutual information (NMI), structural similarity index (SSIM), and peak signal-to-noise ratio (PSNR), between the pseudo CT images obtained using the sGAN method and the ground truth CT (CTgt) images were compared with those of the other two methods via the paired t-test, and the differences were statistically significant. The dice similarity coefficient (DSC) measurement results showed that the pseudo CT images obtained using the sGAN method were more similar to the CTgt images of organs at risk. The dosimetric phantom experiments also showed that the dose distribution between the pseudo CT images synthesized by the new method was similar to that of the CTgt images. CONCLUSIONS: Compared with NSF and CycleGAN methods, the sGAN method can obtain more accurate pseudo CT images, thereby providing a new method for image guidance in radiotherapy for cervical cancer.

Imaging Study of Pseudo-CT Synthesized From Cone-Beam CT Based on 3D CycleGAN in Radiotherapy.

PURPOSE: To propose a synthesis method of pseudo-CT (CTCycleGAN) images based on an improved 3D cycle generative adversarial network (CycleGAN) to solve the limitations of cone-beam CT (CBCT), which cannot be directly applied to the correction of radiotherapy plans. METHODS: The improved U-Net with residual connection and attention gates was used as the generator, and the discriminator was a full convolutional neural network (FCN). The imaging quality of pseudo-CT images is improved by adding a 3D gradient loss function. Fivefold cross-validation was performed to validate our model. Each pseudo CT generated is compared against the real CT image (ground truth CT, CTgt) of the same patient based on mean absolute error (MAE) and structural similarity index (SSIM). The dice similarity coefficient (DSC) coefficient was used to evaluate the segmentation results of pseudo CT and real CT. 3D CycleGAN performance was compared to 2D CycleGAN based on normalized mutual information (NMI) and peak signal-to-noise ratio (PSNR) metrics between the pseudo-CT and CTgt images. The dosimetric accuracy of pseudo-CT images was evaluated by gamma analysis. RESULTS: The MAE metric values between the CTCycleGAN and the real CT in fivefold cross-validation are 52.03 ± 4.26HU, 50.69 ± 5.25HU, 52.48 ± 4.42HU, 51.27 ± 4.56HU, and 51.65 ± 3.97HU, respectively, and the SSIM values are 0.87 ± 0.02, 0.86 ± 0.03, 0.85 ± 0.02, 0.85 ± 0.03, and 0.87 ± 0.03 respectively. The DSC values of the segmentation of bladder, cervix, rectum, and bone between CTCycleGAN and real CT images are 91.58 ± 0.45, 88.14 ± 1.26, 87.23 ± 2.01, and 92.59 ± 0.33, respectively. Compared with 2D CycleGAN, the 3D CycleGAN based pseudo-CT image is closer to the real image, with NMI values of 0.90 ± 0.01 and PSNR values of 30.70 ± 0.78. The gamma pass rate of the dose distribution between CTCycleGAN and CTgt is 97.0% (2%/2 mm). CONCLUSION: The pseudo-CT images obtained based on the improved 3D CycleGAN have more accurate electronic density and anatomical structure.

Stepwise local stitching ultrasound image algorithms based on adaptive iterative threshold Harris corner features.

Herein, a Harris corner detection algorithm is proposed based on the concepts of iterated threshold segmentation and adaptive iterative threshold (AIT-Harris), and a stepwise local stitching algorithm is used to obtain wide-field ultrasound (US) images.Cone-beam computer tomography (CBCT) and US images from 9 cervical cancer patients and 1 prostate cancer patient were examined. In the experiment, corner features were extracted based on the AIT-Harris, Harris, and Morave algorithms. Accordingly, wide-field ultrasonic images were obtained based on the extracted features after local stitching, and the corner matching rates of all tested algorithms were compared. The accuracies of the drawn contours of organs at risk (OARs) were compared based on the stitched ultrasonic images and CBCT.The corner matching rate of the Morave algorithm was compared with those obtained by the Harris and AIT-Harris algorithms, and paired sample t tests were conducted (t = 6.142, t = 31.859, P < .05). The results showed that the differences were statistically significant. The average Dice similarity coefficient between the automatically delineated bladder region based on wide-field US images and the manually delineated bladder region based on ground truth CBCT images was 0.924, and the average Jaccard coefficient was 0.894.The proposed algorithm improved the accuracy of corner detection, and the stitched wide-field US image could modify the delineation range of OARs in the pelvic cavity.

Analysis of Veterinary Drug Residues in Pasteurized Milk Samples in Chinese Milk Bars.

ABSTRACT: The milk bar is an emerging style of retail business that mainly produces pasteurized milk (PM) and other dairy products on-site in many large cities of the People's Republic of China. To date, no data about veterinary drug residues in PM samples produced from milk bars have been reported. The objective of this study was to investigate the safety of PM from a total of 182 PM samples collected from milk bars from 10 provincial capital cities and to analyze the residues of seven classes of 61 veterinary drugs. First, the chemical components were screened with test kits, and then the positive samples were further confirmed by ultraperformance liquid chromatography-tandem mass spectrometry. The results showed that 15 (8.24%) samples were screened positive for veterinary drugs, and six drugs in 11 (6.04%) samples were confirmed. The veterinary drugs detected were penicillin G (2.20%), tetracycline (1.10%), tylosin (1.10%), amoxicillin (0.55%), oxytetracycline (0.55%), and gentamicin (0.55%), with maximum residue levels of 3.4, 11.9, 28.2, 3.0, 26.9, and 63.5 µg kg-1, respectively. Veterinary drug residues were detected as positive in 7 of 10 cities, with the highest detection rate as 14.29% in Urumqi. No positive samples were found in the cities of Nanjing, Tianjin, and Nanning. All detected drug levels were far below the maximum residue levels regulated by China, the European Union, and the Codex Alimentarius Commission. This suggests that the overall veterinary drug residues in PM in milk bars reached the safety code of the country. However, potential risks still exist, and continuous attention should be paid to guarantee the safety of this milk product in the future.

Physicochemical characterization and antitumour activity of exopolysaccharides produced by Lactobacillus casei SB27 from yak milk.

Two high molecular weight fractions (LW1 and LW2) of exopolysaccharides (EPSs) produced by Lactobacillus casei SB27 were isolated from yak milk obtained from the Gansu Tibetan area of China. GC-MS, FTIR spectroscopy, methylation analysis and FE-SEM analysis were performed to elucidate the physicochemical characterization of these two fractions, and their in vitro antitumour activities were also evaluated. The molecular weights (Mws) of LW1 and LW2 as determined by HPGPC were 25.10 and 12.34kDa, respectively. Monosaccharide composition analysis revealed that LW1 and LW2 were mainly composed of galactose (52.4% and 57.4%, mol%) and glucose (29.1% and 22.2%, mol%), respectively. Methylation results showed that the main chain of LW1 likely involves (1→4)-linked Galp and (1→4)-linked Glcp with its side chains being (1→4,6)-linked Galp through the O-6 position connected to the backbone, whereas the main chain of LW2 likely involves (1→4)-linked Galp and (1→4)-linked Glcp with its side chains being (1→3)-Galp through the O-6 position of (1→3,6)-Galp linked to the main chain. Evaluation of the microcosmic morphology, as revealed by FE-SEM analysis of the two EPS fractions, showed a sheet-like appearance with a folded surface and a compact structure. The results from in vitro antitumour tests indicated that both LW1 and LW2 could significantly inhibit the proliferation of HT-29 colorectal cancer cells and up-regulated the expressions of Bad, Bax, Caspase-3 and -8 genes. Finally, TEM images revealed the apoptotic morphological changes of HT-29 cells induced by LW1 and LW2. Our results suggested that LW1 and LW2 possess potential not only for use in functional food products but also as a source of natural antitumour drugs.

Induction of HT-29 cells apoptosis by lactobacilli isolated from fermented products.

A total of 138 lactobacillus strains were obtained from the traditional fermented foods of minority nationalities or infant faeces, respectively. The lactobacillus strains were screened for anticancer effects and probiotic potential. The results showed that 10 strains exerted anti-proliferative activity and higher adhering capability on HT-29 cells. They were then screened for resistance to biological barriers (acid and bile salts), and the four most promising strains were selected. Further analysis revealed that the 4 strains (cell walls and cytoplasm extracts) displayed the high anti-proliferative activity and the large extent of DNA strand breakage in individual cells. Through the selected procedure, cell walls that were extracted from X12, M5 and K14 strains induced apoptosis in HT-29 cells. Further investigation confirmed that apoptosis-inducing ability of cell wall extracts was attributed to the breakdown of mitochondrial membrane potential, which is a known initiation of apoptotic mitochondrial pathway. Cell walls from X12, M5 and K14 strains, were determined to be less harmful to noncancerous Vero cells than to human colon cancer HT-29 cells. These findings suggested that X12, M5 and K14 strains opposing the ability to induce HT-29 cells apoptosis, and cell wall extracts were involved in this apoptosis induction.

Characterization of recombinant Zea mays transglutaminase expressed in Pichia pastoris and its impact on full and non-fat yoghurts.

BACKGROUND: Transglutaminases catalyze post-translational modification of proteins by ε-(γ-glutamyl) links and covalent amide bonds. Research on properties and applications of plant transglutaminases is less developed than in animals and micro-organisms. In a previous study, optimized Zea mays transglutaminase was purified from recombinant Pichia pastoris strain. The main objective of the present study was to characterize this enzyme and assess its effect on the properties of yoghurt. RESULTS: The purified recombinant transglutaminase presented a Km of 3.98 µmol L(-1) and a Vmax of 2711 min(-1) by the fluorometric method. The enzyme was stable after incubation for 30 min below 50 °C and over a broad pH range of 5-8 at -20 °C for 12 h. The results showed that the crosslinking reaction catalyzed by this enzyme could effectively improve the properties of full and non-fat yoghurts. Also, the properties of non-fat yoghurt could be improved similar to the full-fat product by recombinant transglutaminase. CONCLUSION: The application of recombinant transglutaminase in yoghurt indicated that this enzyme could be used as a substitute for microbial transglutaminase in the production of yoghurt, thus providing experimental evidence for the future application of plant transglutaminases in the food industry.

Comparison of enzymatic activity of two linoleic acid isomerases expressed in E. coli.

Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of octadecadienoic fatty acid with conjugated double bonds. CLA possesses many important physiological functions and it can be produced from linoleic acid (LA) by LA isomerases. In this report, we first cloned the genes encoding LA isomerases: C12 isomerases and C9 isomerase, then transformed the recombinant plasmids into Escherichia coli TOP10 and induced E. coli with IPTG (isopropylthio-ß-D-galactoside) to express the recombinant proteins. Next, we purified the isomerases using a HisTrap™ HP column, followed with the analysis by SDS-PAGE or Western blot. Finally, we compared their enzymatic activity by biotransformation of LA into CLA. Plasmids containing LA isomerase genes were successfully constructed. LA isomerases were found expressed in E. coli, and the molecular weight was 64 KD for C12 LA isomerase and 55 KD for C9 LA isomerase. The enzyme activity (9.93 ± 0.01 U/ml for C12 LA isomerase and 8.12 ± 0.02 U/ml for C9 LA isomerase) of both LA isomerases reached the highest when IPTG concentration is 0.2 mM and the induction time is 18 h. After purification, C9 LA isomerase was enriched in peak 4 and C12 LA isomerase was enriched in peak 3. Optimum pH for C9 LA and C12 LA isomerases were 7.5 and 7.0 separately, and optimum temperatures was 37 °C for highest concentration of CLA. The work may provide theoretical significance for an effective production process of CLA for the medical and nutritional purposes.