[Associations between internet addiction, screen time and depressive symptoms]

Objective: To understand the associations between internet addiction, screen time (computer/mobile devices use and television watching time) and depressive symptoms in adults. Methods: A total of 6 932 adults aged <60 years from the Tianjin Chronic Low-grade Sgstemic Inflammation and Health (TCLSIH) Cohort of 2013-2019 were surveyed. The information about their computer/mobile devices use and television watching time were collected by using a self-reported questionnaire. The depressive symptoms were assessed using the self-rating depression scale (SDS). The adults surveyed were divided into two groups: non-depressive symptom group (SDS score <45) and depressive symptom group (SDS score ≥45). The associations between internet addiction, screen time and depressive symptoms were estimated using Cox proportional hazard regression models, with adjusting for multiple confounders. Results: After adjusting for confounding factors, the hazard ratios (HRs) of depressive symptom in the adults who had internet addiction before, had light internet addiction and had moderate or severe internet addiction were 0.83 (95%CI: 0.56-1.23) , 1.20 (95%CI: 1.03-1.41) for light and 1.48 (95%CI: 1.16-1.89), respectively, compared with those without internet addiction. The linear trend test results of the association between internet addiction and depressive symptoms was significant (trend P<0.001). Compared with the adults who used computer/mobile devices for <1 hour/day, the HRs of depressive symptoms in those who used computer/mobile devices for >1 hour, >3 hours, >5 hours and >10 hours were 0.59 (95%CI: 0.40-0.88), 0.58 (95%CI: 0.40-0.85), 0.52 (95%CI: 0.36-0.76) and 0.69 (95%CI: 0.45-1.05) respectively, a U-shaped association was found between computer/mobile devices use time and depressive symptoms (trend P<0.001). Compared with the adults who never watch TV, the HR of depressive symptoms was 1.36 (95%CI:1.09-1.69) for those watching TV for ≥3 hours/day in crude model and 1.34 (95%CI: 1.07-1.68) for those watching TV for ≥3 hours/day in adjusted model (trend P<0.001). Conclusion: Our findings suggested that internet addiction and television watching time were associated with an increased risk of depressive symptoms, while computer/mobile device use time was associated with a reduced risk of depressive symptoms.

[Analysis of Koch phenomenon of Mycobacterium tuberculosis-infected guinea pigs vaccinated with recombinant tuberculosis vaccine AEC/BC02]

OBJECTIVE

To observe the Koch phenomenon of Mycobacterium tuberculosis(MTB)-infected guinea pigs after vaccinated with killed H37Ra bacteria or tuberculosis vaccine candidate AEC/BC02.

METHODS

Eighteen guinea pigs were challenged subcutaneously with 5.0×10(3) CFU MTB and after 40 days were divided into 3 groups (6 per group): NS group, AEC/BC02 group and H37Ra group, which were injected intramuscularly 3 times at 1 day interval with normal saline, AEC/BC02 vaccine and killed H37Ra bacteria respectively. Three weeks after the first vaccination, all guinea pigs were sacrificed to evaluate gross pathological scores for liver, spleen and lung, bacterial loads in lung and spleen, and lung inflammation.

RESULTS

The gross pathological score in H37Ra group (48±26) was lower than that in NS group(62±15), but the difference was not significant (t=1.093, P=0.300). The AEC/BC02 group had a significantly lower gross pathological score (36±15) than NS group (t=2.980, P=0.014). No significant difference between H37Ra group and AEC/BC02 group was observed (t=1.009, P=0.337). The spleen bacterial load [(5.31±0.80) log10 CFU]in H37Ra group was slightly lower than that in NS group[(5.57±0.75) log10 CFU] but the difference was not significant (t=1.581, P=0.574). In AEC/BC02 group bacterial load in the spleen was (4.64±0.64) log10 CFU and significantly lower than NS group (t=2.306, P=0.044) and no significant difference between H37Ra group and AEC/BC02 group was observed (t=1.602, P=0.140). Meanwhile, the lung bacterial load in AEC/BC02 group was (3.71±1.01) log10 CFU and in H37Ra group was (3.82±1.25) log10 CFU. Compared to (4.15±0.69) log10 CFU in the NS group, no significant differences were found (t=0.881, P=0.399; t=0.566, P=0.584, respectively). For the lung inflammation, the inflamed areas in H37Ra group were significantly larger [(33.0±4.4%)] than those in both NS group [(14.8±8.4) %, t=4.719, P=0.001] and AEC/BC02 group [(14.8±8.4) %, t=3.616, P=0.005], and no significant differences were seen between AEC/BC02 group and NS group (t=1.041, P=0.322).

CONCLUSION

The lung inflammation indicated that killed H37Ra bacteria evoked an obvious Koch reaction in the MTB-infected guinea pigs, whereas AEC/BC02 vaccine showed a low risk of causing Koch phenomenon.

Distribution of mitochondrial DNA fragments in the nuclear genome of the honeybee

Nuclear mitochondrial pseudogenes (numts), which originated from mitochondrial DNA (mtDNA) insertions in the nuclear genome, have been detected in many species. The distribution of numts in the honeybee nuclear genome has not yet been fully reported. By referring to the whole honeybee mtDNA sequence and to the recent version of the honeybee nuclear genome, 236 reference sequences were identified by BLAST, with 90 unmapped. The size of the numts ranged from 219 to 3788 bp, and the homologous identity between numts and their corresponding mtDNA fragments varied from 71 to 93%. Furthermore, identified honeybee numts covered nearly all mitochondrial genes and were distributed over all chromosomes. This study provides useful information for further research related to mitochondrial genes and the evolution of the honeybee.

Microbiological, sensory, and electronic nose evaluation of yellowfin tuna under various storage conditions

Microbiological assessment, sensory evaluation, and electronic nose (AromaScan) analysis were performed on yellowfin tuna stored at 0, 4, 10, and 22 degrees C for 0, 1, 3, 5, and 9 days. Fish color, texture, appearance, and odor were evaluated by a trained sensory panel, while aroma-odor properties were evaluated using an AromaScan. Bacterial enumeration was performed using plate count agar containing 1.5% NaCl. Tuna fillets stored at 22 degrees C for 3 days or longer had a bacterial load of over 10(7) CFU/g and were rated not acceptable for consumption (grade C) by the sensory panel. Tuna fillets stored at 4 degrees C for 9 days or 10 degrees C for over 5 days were rated as grade C products and also had a bacterial load of over 10(7) CFU/g. The change in fish quality as determined by AromaScan followed increases in microbiological counts in tuna fillets, indicating that bacterial load can serve as a useful and objective indicator of gross spoilage. Electronic nose devices can be used in conjunction with microbial counts and sensory panels to evaluate the degree of decomposition in tuna during storage.

Chemical, microbiological, and AromaScan evaluation of mahi-mahi fillets under various storage conditions

The quality for mahi-mahi stored at 1.7, 7.2, and 12.8 degrees C for 0, 1, 3, and 5 days was determined using biogenic amine analysis, microbial counts, and sensory evaluation (by a sensory test panel and an AromaScan). Biogenic amines in methanol extracts from mahi-mahi samples were analyzed using capillary electrophoresis (CE) with ultraviolet detection at 210 nm and a gas chromatography (GC) method that can simultaneously determine the contents of putrescine, cadaverine, histamine, spermidine, and spermine within 20 min after pentafluoropropionic anhydride derivatization. A good correlation R2= 0.99) was found between CE and GC methods for detecting histamine in mahi-mahi. Fish quality deteriorated and correlated with increasing microbial numbers. Biogenic amines may be useful indicators for mahi-mahi quality and safety. AromaScan was able to correlate quality changes for mahi-mahi in microbiological and sensory analyses.

Bactericidal activity of isothiocyanate against pathogens on fresh produce

The bactericidal activity of allyl and methyl isothiocyanate (AITC and MITC) was tested with a rifampicin-resistant strain of Salmonella Montevideo and streptomycin-resistant strains of Escherichia coil O157:H7 and Listeria monocytogenes Scott A. Iceberg lettuce inoculated with high (10(7) to 10(8) CFU/g) and low (10(3) to 10(4) CFU/g) concentrations of bacterial pathogens was treated with AITC and MITC in sealed containers at 4 degrees C for 4 days. AITC showed stronger bactericidal activity than MITC against E. coli O157:H7 and Salmonella Montevideo, whereas MITC showed stronger activity against L. monocytogenes than E. coli O157:H7 and Salmonella Montevideo. Up to 8-log reduction occurred with E. coli O157:H7 and Salmonella Montevideo on lettuce following treatment with vapor generated from 400 microl of AITC for 2 and 4 days, respectively. AITC was used to treat tomatoes inoculated with Salmonella Montevideo on stem scars and skin and apples inoculated with E. coli O157:H7 on stem scars. The bactericidal effect of AITC varied with bacteria species and exposure time. Salmonella Montevideo inoculated on tomato skin was more sensitive to AITC than that on stem scars. Treatment with vapor generated from 500 microl of AITC caused an 8-log reduction in bacteria on tomato skin but only a 5-log reduction on tomato stem scars. The bactericidal activity of AITC was weaker for E. coli O157:H7 on apple stem scars; only a 3-log reduction in bacteria occurred when 600 microl of AITC was used.

Determination of chlorate and chlorite and mutagenicity of seafood treated with aqueous chlorine dioxide

The use of chlorine dioxide (ClO(2)) as a potential substitute for aqueous chlorine to improve the quality of seafood products has not been approved by regulatory agencies due to health concerns related to the production of chlorite (ClO(2)(-)) and chlorate (ClO(3)(-)) as well as possible mutagenic/carcinogenic reaction products. Cubes of Atlantic salmon (Salmo salar) and red grouper (Epinephelus morio) were treated with 20 or 200 ppm aqueous chlorine or ClO(2) solutions for 5 min, and extracts of the treated fish cubes and test solutions were checked for mutagenicity using the Ames Salmonella/microsome assay. No mutagenic activity was detected in the treated fish samples or test solutions with ClO(2). Only the sample treated with 200 ppm chlorine showed weak mutagenic activity toward S. typhimurium TA 100. No chlorite residue was detected in sea scallops, mahi-mahi, or shrimp treated with ClO(2) at 3.9-34.9 ppm. However, low levels of chlorate residues were detected in some of the treated samples. In most cases, the increase in chlorate in treated seafood was time- and dose-related.

Establishment of a model of transplantable myelocytic leukemia (L801) in LACA mice

A transplantable myelocytic leukemia model of LACA mice, designated by the name of L801, was established by intravenous injection of spleen cell suspension from mice with radiation-induced myelocytic leukemia into mice of the same strain. Until now, for more than three years, the L801 has maintained stable and rapid growth and has been reproduced for over 130 serial passages. The incidence of leukemia in inoculated animals was approximately 100% and mean survival time was 10.9 +/- 2.1 days. The L801 is of myelocytic type which has been determined by cytological, cytochemical, pathological and ultrastructural observations. Its karyotype was hypodiploid, characterized by modal number of 39, loss of Y chromosome and an abnormal huge marker chromosome. The cell cycle duration of the L801 was 16 h. C-type viral particles were observed under the electron-microscope. The L801 was sensitive, to varying extents, to various anti-tumor agents. We presume that the L801 is a useful tool in studies on mechanism of leukemogenesis, anti-tumor agent screening and treatment of experimental tumors.