Effects of Different Broth Enrichment upon Phage Magnetoelastic Biosensor for Fast Detecting Low <i>Salmonella</i>Counts on Problematic Produce

According to the FDA Bacteriological Analytical Manual (BAM) for Salmonella identification in produce, two pre-enrichment steps with 48 hours of incubation are the golden procedures. Lactose broth is recommended for the first pre-enrichment step medium for leafy greens, and the universal pre-enrichment (UP) broth is for tomatoes. However, the suggested broths were evaluated to have the maximum performance using the culture-dependent methods, and may not be applied to other methods, such as biosensor detection platform. A wireless bacteriophage magnetoelastic (ME) biosensor has been recently developed for real-time or rapid detection of food-borne pathogens in various foods. This affinity-based biosensor utilizes a phage oligonucleotide as the probe to capture target bacteria. In this study, the efficiencies of different pre-enrichment media for early detection of low Salmonella on spinach leaves and tomatoes use ME biosensors to shorten detection time. Four broths of modified peptone water, Lennox broth (LB), lactose broth, and UP broth were selected in this study. Various pre-enrichment times for ME biosensor detection were investigated. After spiking 4 cfu/g Salmonella on the tomatoes surfaces, the phage biosensor was able to detect Salmonella within 5 hours of pre-enrichment comparing to 24 hours in the FDA procedures. For Salmonella spiked spinach leaves, the same medium showed Salmonella positive within 7 hours. This study demonstrated that LB broth is the best medium to shorten pre-enrichment time to pass Salmonella number detection thresholds for ME biosensor detection in spinach and tomatoes when comparing to FDA procedures.

Use of LPS Extracts to Validate Phage Oligopeptide That Binds All <i>Salmonella enterica</i>Serovars

Phage Display technology provides a mechanism for us to make bio-recognition elements on biosensors for detection of Salmonella enterica serovars. In the procedure, the filamentous M13 bacteriophage is used for acquiring peptides that have a high affinity for the target recognition. Our approach in this study was to develop peptide structures in the pIII region of this thread-shaped virus. A phage pIII library was used to perform biopanning for the phage clones to bind the target Salmonella serovars. The clones were bound, washed, eluted and amplified four times. Then, the phage peptides were sequenced tested for specificity using ELISA procedures. In this project to make a biosensor for all relevant Salmonella enterica serovars, we used common LPS salmonellae antigens as targets in the biopanning procedure. This enabled us to have a phage probe specific for all serovars of Salmonella enterica excluding the typhoid organisms. The final phage was then immobilized onto an electromagnetic platform to complete the biosensor, which gives us the real-time ability to measure resonance changes that indicate mass loading. The mass loading is an indication of binding to the target cells. Our current data with an ELISA procedure show the phage probe’s high affinity for salmonellae, very low cross-reactivity with Escherichia coli, Shigella, and no cross-reactivity to Staphylococcus aureus and Listeria monocytogenes. The biosensor with the phage showed that the capture ability for Salmonella serovars is thirty times higher than the control sensor. This biosensor is a candidate for detection of Salmonella in food and other settings.

Living donor liver transplantation for Barcelona clinic liver cancer (BCLC) intermediate-stage hepatocellular carcinoma

Background:Barcelona clinic liver cancer(BCLC)stage B(intermediate stage)hepatocellular carcinoma(HCC)is highly heterogeneous;thus,identifying the most effective treatment for individual patients represents a significant clinical challenge.However,transarterial chemoembolization(TACE)is the only recommended treatment option.Therefore,we aimed to investigate the patient characteristics and outcomes of living donor liver transplantation(LDLT)for BCLC stage B HCC.Methods:A total of 516 patients with BCLC stage B HCC who underwent LDLT(n=104)or did not undergo LDLT(non-LDLT;n=412)between 2004 to 2018 were analyzed by propensity score matching(PSM;1:4)analysis.Factors influencing overall survival(OS)and recurrence were analyzed using Cox’s proportional hazards models.Results:Patients treated with LDLT achieved better OS than the non-LDLT group,including liver-and non-liver related survival(all P<0.001).Multivariate Cox regression analysis showed age>60 years(P=0.006),a neutrophil-lymphocyte ratio(NLR)>4(P=0.016)and>3 locoregional therapies(LRT)before LDLT(P<0.001)were independent risk factors for HCC recurrence.In addition,age>60 years(P<0.001)and>3 LRT before LDLT(P=0.001)were independent risk factors for OS.Using a combination of age,NLR,and LRT before liver transplantation(LT),the patients can be divided into low-risk(none of risk),intermediate-risk(one of risk),and high risk(more than two of risk)groups.There were significant differences in the cumulative HCC recurrence(P<0.001)and mortality(P<0.001)rates among the three groups.Conclusions:LDLT may represent a valuable therapeutic option for selected patients with BCLC stage B HCC.