Target set selection in social networks with tiered influence and activation thresholds

Thanks to the mass adoption of internet and mobile devices, users of the social media can seamlessly and spontaneously connect with their friends, followers and followees. Consequently, social media networks have gradually become the major venue for broadcasting and relaying information, and is casting great influences on the people in many aspects of their daily lives. Thus locating those influential users in social media has become crucially important for the successes of many viral marketing, cyber security, politics, and safety-related applications. In this study, we address the problem through solving the tiered influence and activation thresholds target set selection problem, which is to find the seed nodes that can influence the most users within a limited time frame. Both the minimum influential seeds and maximum influence within budget problems are considered in this study. Besides, this study proposes several models exploiting different requirements on seed nodes selection, such as maximum activation, early activation and dynamic threshold. These time-indexed integer program models suffer from the computational difficulties due to the large numbers of binary variables to model influence actions at each time epoch. To address this challenge, this paper designs and leverages several efficient algorithms, i.e., Graph Partition, Nodes Selection, Greedy algorithm, recursive threshold back algorithm and two-stage approach in time, especially for large-scale networks. Computational results show that it is beneficial to apply either the breadth first search or depth first search greedy algorithms for the large instances. In addition, algorithms based on node selection methods perform better in the long-tailed networks.

[Impact of psoas muscle index on early postoperative mortality and complications after liver transplantation]

Objective: To investigate the relationship between psoas muscle index (PMI) and early postoperative survival rate and the incidence of complications after liver transplantation in adults. Methods: The clinical data of 225 patients (male, n=184; female, n=41) underwent liver transplantation at the Organ Transplantation Department of First Central Clinic Institute of Tianjin Medical University from January 2014 to December 2016 were analyzed, retrospectively.Original disease: hepatitis B liver cirrhosis(44 cases), hepatitis C cirrhosis(10 cases), autoimmune liver cirrhosis(29 cases), other benign liver diseases(24 cases), liver cirrhosis with liver cancer(116 cases), hilar cholangiocarcinoma(1 case) and hepatic vascular sarcoma(1 case). The area of bilateral psoas muscle on the lower edge level of the third lumbar vertebral body was measured through preoperative CT image.The PMI was calculated using this formula: bilateral psoas muscle area (mm(2))/the square of the body height (m(2)). According to the receiver operating characteristic curve and cut-off values, the male and female patients were divided into low PMI group and high PMI group respectively.The χ(2) test, Fisher exact test and t-test was used to compare the differences in perioperative data, survival rate and postoperative complications between the two groups, respectively. Results: There were 44 patients in the low PMI group, and 181 patients in the high PMI group. ICU time was longer (82.5(62.0-128.0) hours vs.69.1(56.0-104.0) hours; P=0.006) and preoperative blood urea nitrogen level (5.86(4.35-15.52) mmol/L vs. 4.94(4.05-7.06) mmol/L; P=0.012) was higher in the low PMI group than those in the high PMI group. Incidence rates of grade 5 complication (18.2%) and grade 4a complication (18.2%) were higher in the low PMI group, and 120-day cumulative survival rate was lower than that in high PMI group(81.8% vs. 95.6%, P=0.001). On the other hand, there were no significant differences in preoperative white blood cell count level, serum creatinine level, operative time, anhepatic period time, intraoperative blood loss, and incidence of postoperative grade 3 complications between the two groups(all P>0.05). Conclusions: There is a significant correlation between PMI and early postoperative survival rate and incidence of complications.Patients with lower PMI has poor prognosis after liver transplantation.

Liver Transplant Recipients With End-Stage Renal Disease Largely Benefit From Kidney Transplantation

BACKGROUND

The incidence of end-stage renal disease (ESRD) after liver transplant (LT) has increased. The actual benefit of kidney transplantation (KT) is not completely understood in LT recipients with ESRD.

METHODS

We analyzed Scientific Registry of Transplant Recipients data for all KT candidates with prior LT from 1998 to 2014; the benefits of KT relative to remaining on dialysis were compared by means of multivariate Cox proportional hazards regression analysis.

RESULTS

The number of these KT candidates with prior LT has tripled from 98 in 1998 to 323 in 2015; LT recipients with ESRD remaining on dialysis have a 2.5-times increase in the risk of liver graft failure and a 3.6-times increase in the risk of patient death compared with these patients receiving KT. The adjusted liver graft and patient survival rates after donors from donation after cardiac death or expanded-criteria donor kidney transplantation were significantly higher than in patients remaining on dialysis in LT recipients with ESRD.

CONCLUSIONS

The number of referrals to KT with prior LT is increasing at a rapid rate. Remaining on dialysis in LT recipients with ESRD has profound increased risks of liver graft failure and patient death in comparison to receiving a KT. LT recipients with ESRD can benefit from expanded-criteria donor and donation after cardiac death kidney transplantation.

Attenuated Salmonella VNP20009 mutant (ΔhtrA) is a promising candidate for bacteria-mediated tumour therapy in hosts with TNFR1 deficiency

VNP20009 is a genetically modified strain of Salmonella typhimurium and has a good anticancer effect wildly used in tumour therapy on animal models. For its clinical application, an accurate bio-safety assessment on sensitive models is necessary. In this study, we use TNFR1 KO mice as a susceptive model to assess the virulence of bacterial VNP20009 and its derivative ΔhtrA. By intraperitoneal administration of Salmonella, the increased lethality was observed in TNFR1 KO mice infected with VNP20009, but not with ΔhtrA. We performed a systemically comparative analysis of their toxicity, and ΔhtrA shows a better bio-safety for TNFR1 KO mice. Since the macrophages with TNFR1 deficiency exhibit a reduced ability of bacteria clearance, ΔhtrA with lower survival ability in normal macrophages restores its viability in TNFR1 KO macrophages. Thus, ΔhtrA was further tested for its antitumour effect in TNFR1 KO mice bearing a B16F10 melanoma model. It displays a moderate antitumour effect, suggesting ΔhtrA instead of VNP20009 might be a promising candidate for bacteria-mediated tumour therapy specific to those with low immunity.

SIGNIFICANT AND IMPACT OF THE STUDY

VNP20009 is attenuated Salmonella with a good safety widely used for tumour-targeting bacterial therapies. Little is known about its toxicity in hosts with low immunity. This study is the first systemically comparative analysis of their toxicity of VNP20009 and its mutant ΔhtrA in TNFR1-KO mice. Research on toxicity of tumour-targeting Salmonella in mice with immunodeficiency can facilitate the optimization of bacterial therapies with reduced adverse effects in future clinical trials.

Mass spectrometric screening method for microcystins in cyanobacteria

A screening method for microcystins in cyanobacteria, which consists of the formation of 3-methoxy-2-methyl-4-phenylbutyric acid as an oxidation product of microcystins by ozonolysis, and detection of 3-methoxy-2-methyl-4-phenylbutyric acid by thermospray-liquid chromatography/mass spectrometry or electron ionization-gas chromatography/mass spectrometry using selected ion monitoring, was developed. The ozonolysis made it possible to significantly reduce the formation times of 3-methoxy-2-methyl-4-phenylbutyric acid because the previously required extraction, clean-up and other procedures could be entirely eliminated. The resulting intact 2-methyl-4-phenylbutyric acid was directly analyzed by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry, and the procedures from ozonolysis to analysis of microcystins at the pmole levels were performed within only 30 min. The calibration curves obtained by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry analysis showed a linear relationship from 14 to 830 pmole and from 2.5 to 100 pmole of microcystin-LR, respectively. The method was applied to the detection and determination of the total amount of microcystins in bloom and cultured samples, showing that it provided a means of not only screening for microcystins but of their accurate quantitation.

Laser photocoagulation treatment of choroidal melanoma

Ten cases of choroidal melanoma were treated with Argon and/or Krypton laser photocoagulation in this retrospective study. Each patient received an average of 9.6 laser treatment sessions. Three female and seven male patients were treated and followed for an average of 69.9 months. Clinical regression was observed in seven cases (70%). Tumour size in these successfully treated cases ranged from 4.5 x 5.0 x 1.5 mm to 7.0 x 7.0 x 3.5 mm. Continued growth occurred in one case (10%), tumour recurrence which failed to respond to additional laser treatment in another (10%), and although a recurrence appeared to respond to additional laser in a third case (the largest tumour in the series 11.0 x 9.0 x 2.5 mm) extraocular extension was found at enucleation (10%). Complications of laser treatment included cystoid macular oedema (Case 5), branch retinal vein occlusion (Cases 3 and 6), vitreous haemorrhage from neovascularisation at the edge of the scar, optic atrophy and thrombotic glaucoma (Case 8), and macular involvement by laser (Cases 4, 7 and 10). All patients remain alive without any clinical evidence of metastatic disease at the end of the follow-up period. These results suggest that laser photocoagulation treatment is a useful option in the management of small choroidal melanomas. It avoids the psychological trauma of enucleation, and maintains some vision, without compromising life expectancy.