Experimental study on the effects of different exposure conditions and contrast agent concentrations on spectral computed tomography virtual non-contrast images.

Background: The early diagnosis of thrombosis and fat embolism is important for subsequent treatment regimens. Spectral computed tomography (CT) virtual non-contrast (VNC) scanning can not only accurately diagnose thrombosis and medium fat embolism but can also reduce the radiation dose and scanning time. However, there is a relative paucity of studies on what contrast concentration and exposure conditions are best for the quality of VNC images. To address this issue, this study aimed to investigate the effects of different exposure conditions and contrast concentrations on the quality of VNC images of low-density substances in spectral CT. Methods: Four solution groups [i.e., groups A (15 mgI/mL), B (10 mgI/mL), C (5 mgI/mL), and D (the control group)] were matched with normal saline and contrast agent groups. Four groups of solution, duck blood clots, and fat were injected into four sections of the pig large intestine, respectively. CT scans with different exposure amounts were performed under the condition of 120 KV. Comparing the true non-contrast (TNC) image based on solution D group with the VNC images of the other three solution groups. The differences in the CT values, standard deviation (SD) values, and contrast noise ratio (CNR) values of the duck blood and fat under different iodine concentrations and exposures were compared. The image quality was evaluated using a three-point method and the Kappa consistency test was performed. The consistency of the tissue CT values in the TNC and VNC images was analyzed by drawing Bland-Altman scatter plots. Results: The CT values of the duck blood in the VNC20mAs and VNCC groups were lower than those in the TNC groups (P<0.05). Under different exposures and contrast agent concentrations, the CT value of the fat in the VNC group was higher than that in the TNC group (P<0.05). The SD values of the duck blood and fat in three groups (i.e., groups A, B, and C) were lower than those in the TNC group (P<0.05). The CNR value of the duck blood in the VNC20mAs group was lower than that in the TNC group (Z=-2.10, P=0.04), and the CNR values of the duck blood and fat in the VNC group were higher than those in the TNC groups in the remaining different exposure and concentration groups (P<0.05). The CT values of the lesions in the two groups were consistent, and there were no statistically significant differences between the subjective scores of the TNC and VNC images (z=-1.34, P=0.18); the subjective evaluations of the two physicians had good consistency (K=0.80). Conclusions: Under the conditions of higher contrast agent concentrations and proper exposure conditions, the VNC images were better able to restore the CT values of the blood clots, reduce the SD values of the blood clots and fat. In addition, and improve the CNR values of the blood clots and fat. In addition, the quality of the two images was similar.

A review of tamoxifen administration regimen optimization for Cre/loxp system in mouse bone study.

Gene knockout is a technique routinely used in basic experimental research, particularly in mouse skeletal and developmental studies. Tamoxifen-induced Cre/loxp system is known for its temporal and spatial precision and commonly utilized by researchers. However, tamoxifen has been shown its side effects on affecting the phenotype of mouse bone directly. This review aimed to optimize tamoxifen administration regimens including its dosage and duration, to identify an optimal induction strategy that minimizes potential side effects while maintaining recombination efficacy. This study will help researchers in designing gene knockout experiments in bone when using tamoxifen.

Correlation between serum prealbumin and prognosis of patients with hepatocellular carcinoma after hepatectomy.

OBJECTIVE: To determine whether serum prealbumin levels are associated with long-term survival after hepatectomy in patients with primary hepatocellular carcinoma(HCC). METHODS: A consecutive sample of 526 patients with HCC who underwent potentially curative hepatectomy from August 2007 to August 2010 was retrospectively analyzed. Patients were classified as having normal or reduced serum prealbumin based on cut-off values of 200 or 182 mg/L. RESULTS: Multivariate analysis identified the preoperative level of serum prealbumin as an independent prognostic factor of long-term survival (P < 0.05): Survival was significantly better for those with normal levels than for those with reduced levels, based on either cut-off value. Similar results were observed in subgroup analyses based on the degree of cirrhosis, level of ɑ-fetoprotein and Barcelona Clinic Liver Cancer stage. CONCLUSIONS: Preoperative level of serum prealbumin may be useful for predicting long-term survival in patients with HCC after hepatectomy.

Enhancement of ε-poly-L-lysine production coupled with precursor L-lysine feeding in glucose-glycerol co-fermentation by Streptomyces sp. M-Z18.

ε-Poly-L-lysine (ε-PL), one of the only two homo-poly amino acids known in nature, is used as a preservative. In this study, strategies of feeding precursor L-lysine into 5 L laboratory scale fermenters, including optimization of L-lysine concentration and time, was investigated to optimize the production of ε-PL by Streptomyces sp. M-Z18. The optimized strategy was then used in ε-PL fed-batch fermentation in which glucose and glycerol served as mixed carbon sources. In this way, a novel ε-PL production strategy involving precursor L-lysine coupled with glucose-glycerol co-fermentation was developed. Under optimal conditions, ε-PL production reached 37.6 g/l, which was 6.2 % greater than in a previous study in which glucose and glycerol co-fermentation was performed without added L-lysine (35.14 g/l). To the best of our knowledge, this is the first report of the enhancement of ε-PL production through L-lysine feeding to evaluate the use of fermenters. Meanwhile, the role of L-lysine in the promotion of ε-PL production, participating ε-PL synthesis as a whole, was first determined using the L-[U-(13)C] lysine labeling method. It has been suggested that the bottleneck of ε-PL synthesis in Streptomyces sp. M-Z18 is in the biosynthesis of precursor L-lysine. The information obtained in the present work may facilitate strain improvement and efficient large-scale ε-PL production.

Culture medium containing glucose and glycerol as a mixed carbon source improves ε-poly-L-lysine production by Streptomyces sp. M-Z18.

To improve the efficiency of ε-poly-L-lysine (ε-PL) production by Streptomyces sp. M-Z18, batch and fed-batch fermentations with glucose and glycerol (co-fermentations) were performed. The batch fermentations showed that the initial ratio of glucose to glycerol plays an important role in glucose/glycerol co-fermentation. The optimal glucose/glycerol weight ratio was 30/30; this resulted in a maximum ε-PL productivity of 5.26 g/L/d. Glucose and glycerol were consumed synergistically during the co-fermentation process, and the length of time during which the substrate was exhausted was significantly shortened compared with the single carbon source fermentation. Under optimized conditions, fed-batch fermentations with glucose and glycerol as a mixed carbon source achieved maximum ε-PL concentration and productivity values of 35.14 g/L and 4.85 g/L/d, respectively. These values were respectively 1.43- and 1.39-, and 1.17- and 1.16-folds higher than those obtained from fermentations with glucose and glycerol as single carbon sources. The present study is the first to suggest that glucose/glycerol co-fermentation may be an efficient strategy for ε-PL production by Streptomyces sp. M-Z18.