Advance in the degradation of biodegradable plastics in different environments / 生物工程学报

With the continuously increasing demands of plastic products in the current society, the challenge of disposing plastic waste is constantly increasing, leading to the urgent need of mitigating plastic pollution. As a consequence, much attention has been paid to biodegradable plastics due to their degradability in a bio-active environment under certain conditions. Biodegradable plastics herald vast development potentials and considerable market prospects. The degradation of numerous types of biodegradable plastics will be affected by many factors. A thorough understanding of degradation mechanisms as well as functional microbial strains and enzymes is the key to comprehensive utilization and efficient treatment and disposal of biodegradable plastics. The article summarized the types, properties, advantages and disadvantages, and main applications of common biodegradable plastics. The degradation mechanisms, functional microbial strains and enzymes, as well as the degradation degree and duration under different environmental conditions, were also summarized. This review may help better understand the degradation of biodegradable plastics wastes.

Impact of variations in fatty liver on sonographic detection of focal hepatic lesions originally identified by CT

PURPOSE: The aim of this study was to investigate the influence of variations in fatty liver on the ultrasonographic detection of focal liver lesions. METHODS: A total of 229 patients with varying degrees of fatty liver and focal liver lesions and 200 patients with focal liver lesions but no fatty liver were randomly selected for inclusion in groups I and II, respectively. Findings of focal liver lesions identified on computed tomography were taken as the reference, and findings on ultrasonography were compared with them. RESULTS: The number of focal liver lesions in groups I and II were 501 and 413, respectively. The ultrasonographic detection rates of focal liver lesions in groups I and II were 86.8% (435/501) and 94.2% (389/413), respectively. Comparison of the detection of the focal lesions between patients with and without fatty liver or different grades of fatty liver were as follows: mild fatty liver (162/177) vs. liver without fat infiltration (389/413) (P=0.277); mild fatty liver (162/177) vs. moderate fatty liver (190/212) (P=0.604); mild fatty liver (162/177) vs. severe fatty liver (83/112) (P<0.001); moderate fatty liver (190/212) vs. liver without fat infiltration (389/413) (P=0.051); moderate fatty liver (190/212) vs. severe fatty liver (83/112) (P<0.001); severe fatty liver (83/112) vs. liver without fat infiltration (389/413) (P<0.001); and fatty liver (435/501) vs. liver without fat infiltration (389/413) (P<0.001). CONCLUSION: Mild and moderate fatty liver are not significantly associated with the visualization of the lesion, while severe fatty liver usually impairs the detection of focal lesions in the liver. If a patient with severe fatty liver is suspected to have a liver tumor, ultrasonography should only be chosen cautiously in case of a missed diagnosis.

Changes of regulatory T cells in patients with hepatocellular carcinoma after percutaneous cool-tip radiofrequency ablation and its influence on the prognosis / 介入放射学杂志

Objective To investigate the changes of regulatory T cells (Treg) in patients with hepatocellular carcinoma (HCC) after ultrasound- guided percutaneous cool- tip radiofrequency ablation (RFA), and to discuss its influence on the prognosis. Methods A total of 30 patients with HCC were enrolled in this study. The percentage of Treg in peripheral blood was estimated with flow cytometry before RFA and one, 4, 7 and 12 months after RFA. During the follow-up period, the therapeutic effects were evaluated by contrast enhanced sonography or contrast enhanced CT scanning. By using the methods of receiver operating characteristic (ROC) curve and Kaplan-Meier survival function, the correlation of Treg dynamic changes with the progression-free survival time was analyzed. Results One month after RTA, the tumor response (TR) rate in the 30 patients was 93.3% (28/30), the tumor progression (TP) rate was 6.67%(2/30). The percentage of Treg before RFA was (9.42 ± 1.16)%, which decreased to (6.55 ± 0.97)% one month after RFA, the difference was statistically significant (t = 15.325, P 4.82%. PFS of patients with reaching Treg nadir≥5.5 months was significantly higher than that of patients with reaching Treg nadir<5.5 months. Log-rank test results were字2=5.207, P=0.023; 字2=22.079, P < 0.001, respectively. Conclusion Percutaneous cool-tip radiofrequency ablation can decrease the percentage of Treg cells. Besides, Treg nadir and the time reaching Treg nadir can reflect the prognosis of HCC patients after RFA to a certain extent.

Codon optimization of the rabbit hemorrhagic disease virus (RHDV) capsid gene leads to increased gene expression in Spodoptera frugiperda 9 (Sf9) cells

Rabbit hemorrhagic disease (RHD) is contagious and highly lethal. Commercial vaccines against RHD are produced from the livers of experimentally infected rabbits. Although several groups have reported that recombinant subunit vaccines against rabbit hemorrhagic disease virus (RHDV) are promising, application of the vaccines has been restricted due to high production costs or low yield. In the present study, we performed codon optimization of the capsid gene to increase the number of preference codons and eliminate rare codons in Spodoptera frugiperda 9 (Sf9) cells. The capsid gene was then subcloned into the pFastBac plasmid, and the recombinant baculoviruses were identified with a plaque assay. As expected, expression of the optimized capsid protein was markedly increased in the Sf9 cells, and the recombinant capsid proteins self-assembled into virus-like particles (VLPs) that were released into the cell supernatant. Rabbits inoculated with the supernatant and the purified VLPs were protected against RHDV challenge. A rapid, specific antibody response against RHDV was detected by an ELISA in all of the experimental groups. In conclusion, this strategy of producing a recombinant subunit vaccine antigen can be used to develop a low-cost, insect cell-derived recombinant subunit vaccine against RHDV.

Construction and immunogenicity of recombinant adenovirus co-expressing the GP5 and M protein of porcine reproduction and respriratory syndrome virus in mice / 生物工程学报

FMDV 2A peptide was introduced as a linker between GP5 and M protein of porcine reproduction and respiratory syndrome virus (PRRSV) to allow automatic self-cleavage the polyproteins. This strategy simultaneously displayed the neutralizing action of GP5 protein and cell-mediated immunity of M protein. We put them into the expression cassette of adenovirus vector. The results of RT-PCR, IFA and Western blotting showed that GP5 and M protein were not only expressed correctly, but also self-cleavaged and assemble heterodimers formation. To detect the advantages of rAd-GP5-2A-M, we also constructed some other recombinant adenoviruses (rAd-GP5, rAd-M and rAd-GP5-M) as control. After inoculated subcutaneously into BALB/c mice, the four recombinant adenoviruses can induce PRRSV-specific antibodies and cell-mediated immune response, but the level of humoral and cell-mediated immune response against PRRSV induced by rAd-GP5-2A-M is the strongest among the four recombinant adenoviruses. All of these suggested that it is possible to develop one multi-gene engineering vaccine utilizing FMDV 2A peptide, and also provided a novel strategy for developing other viral disease vaccine.

NUTRITION STUDIES OF HUMANS DURING A HELIUM-OXYGEN DIVE TO A SIMULATED DEPTH OF 200M / 营养学报

Nutrition studies were made on four divers performing a helium-oxygen saturation dive to a simulated depth of 200m in a hyperbaric chamber for about seven days. Daily intake of food was surveyed by regular weighing method and its calories and nutrients were calculated from Chinese food composition table. Fasting blood and 24h urine samples were collected on several occasions before, during and after the dive for estimation of free amino acid, nitrogen and minerals. Vitamin load test was conducted for evaluation of vitamin status. The results showed that during the dive intakes of cereal, meat and oil of divers were decreased, but vegetable, fruit and beverage intakes increased. An average body weight loss of 1.75 kg was found after a 7-day period, but little changes in the body fat. Free amino acid levels of serum and urinary output were reduced, especially the essential amino acids. The urinary excretion of minerals was in an acceptable range, but thiamin decreased markedly and not returned to an acceptable range until 10 days after leaving the hyperbaric chamber.

NUTRITION STUDIES DURING N2 -O2 SATURATION DIVING / 营养学报

Nutrition studies of saturation/excursion dives were made in a hyper-baric chamber. Seven divers were investigated during a period of 26-day N2-O2 saturation dive to 36.5m with excursion to 60-75m using only air. Daily intake of food was surveyed by regular weighing method. The caloric and nutrient intakes were calculated from Chinese food composition tables. Urine samples were collected for estimation of vitamin B1, B2, 4-pyridoxic acid, ascorbic acid and also nitrogen. During the dive they lost the appe- tite for meat and oil, instead they preferred vegetables, fruits and beverages. Thus energy, protein and lipid decreased and a weight loss was observed. The urinary excretion of certain vitamins was reduced, especially marked with thiamine. Accordingly a suggestion on the allowance of certain nutrients was proposed.

A STEPWISE REGRESSION ANALYSIS FOR BODY DENSITY AND FAT ON ANTHROPOMETRIC MEASUREMENTS OF CHINESE MALES / 营养学报

Body composition by body voluraetry (water displacement), height, body weight, 5 skinfolds thickness and circumference of 6 body parts were measured in 101 Chinese men. A stepwise regression analysis of these data gave the following regression equations.Body density = 1.11197 - 0.00228S1 - 0.00046S2 - 0.00039S3-Fat(%)= 0.91137S1 + 0.17871S2 + 0.15381S3 - 3.60146S1. S2 and S3 represent the skinfolds thickness of tricepital, subscapular, and suprailiac respectively.Lean body weight = Body weight. (1-Fat%)