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  • Author or Editor: Han Xu x
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In this study, Lactobacillus pentosus expressing porcine lactoferrin (pLF) was tested for in vitro antibacterial activity and for its ability to enhance immunity induced by an orally administered Aujeszky’s disease virus (ADV) vaccine. The cDNA encoding N-terminus of pLF was cloned into a Lactobacillus-specific plasmid to produce L. pentosus pLF expressing transformants (pPG612.1-pLFN/ L. pentosus). The antimicrobial activity of the recombinant pLF protein inhibited bacterial growth in vitro. The supernatant of pPG612.1-pLF-N/L. pentosus had an inhibitory effect on Staphylococcus aureus strain CVCC26003, Bacillus subtilis strain CVCC63501, Escherichia coli strain CVCC10141 and Salmonella enterica ssp. enterica Choleraesuis strain CVCC79102, while it did not inhibit the growth of Lactobacillus casei strain ATCC393. A mouse model was established to test the effectiveness of the orally administered probiotic L. pentosus recombinant strain in the gastrointestinal tract. Mice were immunised with an attenuated porcine Aujeszky’s disease virus (ADV) vaccine. Serum antibody levels determined using a mouse Aujeszky’s disease IgG ELISA showed that IgG levels were significantly higher in the pPG612.1-pLFN/L. pentosus group than in the PBS and Lactobacillus pentosus groups at days 7 and 21 (P < 0.01) and at day 14 (P < 0.05), indicating that this oral recombinant strain can improve the effectiveness of the vaccine and play a role in immune enhancement through humoral immunity. These results suggest that the recombinant Lactobacillus pentosus not only has the beneficial characteristics of lactic acid bacteria but also produces biologically functional lactoferrin.

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Abstract

Background and aims

Problematic use of the internet (PUI) among adolescents has become one of the public problems around the world. Understanding the developmental trajectory of PUI may be beneficial to develop prevention and intervention. The current study aimed to identify the developmental trajectories of PUI among adolescents, considering individual differences over time. And also explored how familial factors contributed to the identified trajectories, and the relationship between PUI changes over time and social, mental health, and academic functioning.

Methods

A total of 1,149 adolescents (Mage  = 15.82, SD = 0.61; 55.27% girls at Wave 1) participated in assessments at four time points, using 6-month assessment intervals.

Results

Based on a latent class growth model, three trajectories of PUI were identified: Low Decreasing, Moderate Increasing, and High Increasing groups. Multivariate logistic regression analyses suggested that inter-parental conflicts and childhood maltreatment served as negative familial predictors for the risk trajectories of PUI (i.e., Moderate Increasing and High Increasing groups). Additionally, adolescents in these two groups displayed more estranged interpersonal relationships, more mental health difficulties, and poorer academic functioning.

Discussion and conclusions

It is important to consider individual differences in understanding the developmental patterns of PUI among adolescents. Identifying family predictors and the behavioral outcome associated with groups with different developmental trajectories of PUI, which may help to understand better risk factors related to specific developmental patterns of PUI and its adverse correlates. The findings highlight a need to develop more specific effective intervention programs for individuals displaying different problematic developmental trajectories with PUI.

Open access