Recent Advancements in Mechanistic Studies of Palladium- and Nickel-Catalyzed Ethylene Copolymerization with Polar Monomers

The introduction of polar functional groups into polyolefin chain structures creates opportunities to enhance specific properties, such as adhesion, dyeability, printability, compatibility, thermal stability, and electrical conductivity, which widen the range of potential applications for these modified materials. Transition metal catalysts, especially late transition metals, have proven to be highly effective in copolymerization processes due to their reduced Lewis acidity and electrophilicity. However, when compared to the significant progress and summary of synthetic methods, there is a distinct lack of a comprehensive summary of mechanistic studies pertaining to the catalytic systems involved in ethylene copolymerization catalyzed by palladium and nickel catalysts. In this review, we have provided a comprehensive summary of the latest developments in mechanistic studies of ethylene copolymerization with polar monomers catalyzed by late-transition-metal complexes. Experimental and computational methods were employed to conduct a detailed investigation of these organic and organometallic systems. It is mainly focused on ligand substitution, changes in binding modes, ethylene/polar monomer insertion, chelate opening, and β-H elimination. Factors that control the catalytic activity, molecular weight, comonomer incorporation ratios, and branch content are analyzed, these include steric repulsions between ligands and monomers, electronic effects arising from both ligands and monomers, and so on.

Recent Advances in the Copolymerization of Ethylene with Polar Comonomers by Nickel Catalysts

The less-expensive and earth-abundant nickel catalyst is highly promising in the copolymerization of ethylene with polar monomers and has thus attracted increasing attention in both industry and academia. Herein, we have summarized the recent advancements made in the state-of-the-art nickel catalysts with different types of ligands for ethylene copolymerization and how these modifications influence the catalyst performance, as well as new polymerization modulation strategies. With regard to α-diimine, salicylaldimine/ketoiminato, phosphino-phenolate, phosphine-sulfonate, bisphospnine monoxide, N-heterocyclic carbene and other unclassified chelates, the properties of each catalyst and fine modulation of key copolymerization parameters (activity, molecular weight, comonomer incorporation rate, etc.) are revealed in detail. Despite significant achievements, many opportunities and possibilities are yet to be fully addressed, and a brief outlook on the future development and long-standing challenges is provided.

Precipitation Polymerization: A Powerful Tool for Preparation of Uniform Polymer Particles

Precipitation polymerization (PP) is a powerful tool to prepare various types of uniform polymer particles owing to its outstanding advantages of easy operation and the absence of any surfactant. Several PP approaches have been developed up to now, including traditional thermo-induced precipitation polymerization (TRPP), distillation precipitation polymerization (DPP), reflux precipitation polymerization (RPP), photoinduced precipitation polymerization (PPP), solvothermal precipitation polymerization (SPP), controlled/‘‘living’’ radical precipitation polymerization (CRPP) and self-stabilized precipitation polymerization (2SPP). In this review, a general introduction to the categories, mechanisms, and applications of precipitation polymerization and the recent developments are presented, proving that PP has great potential to become one of the most attractive polymerization techniques in materials science and bio-medical areas.

Cell-free DNA from bile outperformed plasma as a potential alternative to tissue biopsy in biliary tract cancer

BACKGROUND

Biliary tract cancers (BTCs) are rare and highly heterogenous malignant neoplasms. Because obtaining BTC tissues is challenging, the purpose of this study was to explore the potential roles of bile as a liquid biopsy medium in patients with BTC.

PATIENTS AND METHODS

Sixty-nine consecutive patients with suspected BTC were prospectively enrolled in this study. Capture-based targeted sequencing was performed on tumor tissues, whole blood cells, plasma, and bile samples using a large panel consisting of 520 cancer-related genes.

RESULTS

Of the 28 patients enrolled in this cohort, tumor tissues were available in eight patients, and plasma and bile were available in 28 patients. Somatic mutations were detected in 100% (8/8), 71.4% (20/28), and 53.6% (15/28) of samples comprising tumor tissue DNA, bile cell-free DNA (cfDNA), and plasma cfDNA, respectively. Bile cfDNA showed a significantly higher maximum allele frequency than plasma cfDNA (P = 0.0032). There were 56.2% of somatic single-nucleotide variant (SNVs)/insertions and deletions (indels) shared between bile and plasma cfDNA. When considering the genetic profiles of tumor tissues as the gold standard, the by-variant sensitivity and positive predictive value for SNVs/indels in bile cfDNA positive for somatic mutations were both 95.5%. The overall concordance for SNVs/indels in bile was significantly higher than that in plasma (99.1% versus 78.3%, P < 0.0001). Moreover, the sensitivity of CA 19-9 combined with bile cfDNA achieved 96.4% in BTC diagnosis.

CONCLUSION

We demonstrated that bile cfDNA was superior to plasma cfDNA in the detection of tumor-related genomic alterations. Bile cfDNA as a minimally invasive liquid biopsy medium might be a supplemental approach to confirm BTC diagnosis.

MiR-129-2 weakens proliferation and promotes apoptosis of liver cancer cells by suppressing the Wnt signaling pathway

OBJECTIVE

To explore the effects of micro ribonucleic acid-129-2 (miR-129-2) on proliferation and migration of liver cancer cells and its possible mechanism.

PATIENTS AND METHODS

The expression level of miR-129-2 was measured in liver cancer tissues and adjacent tissues from patients with liver cancer. Its level in liver cancer HepG2 cells and normal liver cells L-02 was also detected via quantitative polymerase chain reaction (qPCR). MiR-192-2 overexpression model was established in the HepG2 cell line. The proliferation and apoptosis levels of cells were determined by methyl thiazolyl tetrazolium (MTT) assay and flow cytometry, respectively. Wound healing assay was performed to detect the migration ability of cells. The expressions level of genes in the Wnt signaling pathway were measured through Western blotting. Xenograft tumor model was conducted in nude mice for exploring the in vivo effects of miR-129-2 on liver cancer growth.

RESULTS

The expression level of miR-129-2 was significantly lower in liver cancer tissues than that in adjacent tissues (p<0.01), and it was overtly lower in HepG2 cells than that in L-02 cells (p<0.01). Overexpression of miR-129-2 weakened proliferation and migration abilities of liver cancer cells (p<0.01), and evidently increased apoptosis level (p<0.01). Sex-determining region Y-related HMG-box 4 (Sox4) and matrix metalloproteinase-2 (MMP-2) were downregulated, while phosphorylated glycogen synthase kinase-3β (p-GSK3β) was upregulated in liver cancer cells overexpressing miR-129-2. Besides, the weight and volume of tumors in nude mice bearing liver cancer were significantly smaller after overexpression of miR-129-2.

CONCLUSIONS

MiR-129-2 weakens proliferation and migration and stimulates apoptosis in liver cancer cells mainly by downregulating Sox4 and inactivating the Wnt signaling pathway.

Risk of volume reduction associated with sodium-glucose cotransporter-2 inhibitors treatment: a meta-analysis of randomized controlled trials

Introduction

Sodium-glucose cotransporter-2 (SGLT2) inhibitors is a newly class of drug which improving glycemia by enhancing glycosuria, subsequently reducing blood pressure by osmotic diuresis and natriuresis. There are multiple large-scale randomized control trials demonstrating that SGLT2 inhibitors had salutary effect on cardiovascular-renal outcome, especially on heart failure. Although SGLT2 inhibitors exhibited promising potential value on treatment for type 2 diabetes mellitus (T2DM) with cardiovascular-renal comorbidities, the potential adverse events (AEs) related to osmotic diuresis such as volume reduction should not be neglected. Moreover, older individuals, those with moderate renal impairment, and those receiving antihypertensive therapies are susceptible to adverse events related to volume reduction.

Purpose

To assess the association between sodium-glucose cotransporter-2 inhibitors and risk of volume reduction in patients with type 2 diabetes mellitus.

Methods

A systematic literature retrieval was performed in PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception up to 10 December 2019, Data for study characteristics and outcomes of interest were extracted from each eligible study. Pooled risk ratios (RRs) with 95% confidence interval (CI) for volume reduction was calculated using random-effects model.

Result

A total of 51 studies (n=56,866) were included in our meta-analysis, with a result of 1,337 incident volume reduction cases (814 in the SGLT2 inhibitors group, 523 in the control group). The pooled RR was 1.15 (95% CI: 1.03–1.28). It is evident that receiving SGLT2 inhibitors had increased the risk of volume reduction, when stratified by placebo-control or active-control the result was consistent.

Conclusion

Our meta-analysis has demonstrated that SGLT2 inhibitors increase the risk of volume reduction in patients with T2DM. It is necessary to attention for the risk of volume reduction associated with SGLT2 inhibitors, especially in older individuals, those with moderate renal impairment, and those receiving antihypertensive therapies.

SGLT2 inhibitors vs control

Funding Acknowledgement

Type of funding source: None

Phylogeny of Vibrio cholerae based on recA sequence

We sequenced a 705-bp fragment of the recA gene from 113 Vibrio cholerae strains and closely related species. One hundred eighty-seven nucleotides were phylogenetically informative, 55 were phylogenetically uninformative, and 463 were invariant. Not unexpectedly, Vibrio parahaemolyticus and Vibrio vulnificus strains formed out-groups; we also identified isolates which resembled V. cholerae biochemically but which did not cluster with V. cholerae. In many instances, V. cholerae serogroup designations did not correlate with phylogeny, as reflected by recA sequence divergence. This observation is consistent with the idea that there is horizontal transfer of O-antigen biosynthesis genes among V. cholerae strains.

[MBP content in serum after closed diffuse cranial injury in rats]

The MBP content change in serum was observed by ELISA in rats with experimental closed diffuse cranial injury. The MBP content was 6.1633 +/- 1.5301 ng/ml (X +/- S) in the normal group, 11.3818 +/- 2.6574 ng/ml in the first group died immediately after injury, 10.8319 +/- 2.3135 ng/ml in the second group of 15 min after injury. This increased level of MBP was lasting in the following 3 days and returned to normal at the 4th and 5th day after injury. The difference of the MBP levels between the groups after injury and that in the normal group is significant (P < 0.01).

[Genetic polymorphism of inter-alpha-trypsin inhibitor in six Chinese populations]

OBJECTIVE

To understand the distribution of allele frequencies of inter-alpha-trypsin inhibitor(ITI) in Chinese populations.

METHODS

The polymorphism of this protein in six Chinese populations was investigated using isoelectric focusing followed by immunoblotting technique.

RESULTS

Three common alleles, ITI*1, ITI*2, and ITI*3 were observed in four populations, namely Han living in Jilin, Mongol in Hailaer, Tibetan in Lasa, and Bai in Dali respectively. In other two populations, Zhuang in Guangxi and Han in Guangdong, only ITI*1 and ITI*2 were observed. For these populations, the frequency of ITI*1 ranges from 0.5500 to 0.7525; that of ITI*2 from 0.2475 to 0.4322; and that of ITI*3 from 0.0034 to 0.0729.

CONCLUSION

This study reveals that there is no parallel relationship between variation of allele frequencies and geographic differences.

[Genetic polymorphism of FXIII B subunit in seven Chinese populations]

OBJECTIVE

To understand the distribution of allele frequencies of blood factor XIIIB subunit(FXIIIB) in Chinese populations and evaluate the genetic polymorphism of FXIIIB for the purposes of population genetics and forensic haemogenetics.

METHODS

The genetic polymorphism of FXIIIB subunit in seven Chinese populations was investigated. Isoelectrofocusing technique on polyoacrylamid gels followed by immunoblotting was used to determine the phenotype of individuals in each population sample.

RESULTS

There were three common alleles in all the seven Chinese populations. The frequency of FXIIIB*3 was the highest, that of FXIIIB*2 was the lowest, and the one of FXXIIIB*1 was at the middle. All of them reached to the polymorphism's level. A rare variant allele was also found in some Chinese populations. Comparison of the constituents of FXIIIB phenotypes in the seven populations showed that there was no significant difference (P>0.05). The distribution of the allele frequencies in these populations reflected most likely the mode of the distribution in all Chinese populations. The phylogenetic tree and genetic distance, based on the allele frequencies of FXIIIB differentiated the populations in the world into the main ethnic groups as what other authors reported.

CONCLUSION

FXIIIB is a useful genetic marker for population genetics and forensic haemogenetics.

Dissociation of basal turnover and cytokine-induced transcript stabilization of the human cyclooxygenase-2 mRNA by mutagenesis of the 3'-untranslated region

The immediate early gene cyclooxygenase-2 (Cox-2), which encodes the inducible prostaglandin synthase enzyme, is regulated at the level of post-transcriptional mRNA turnover. In this study, the functional role of the 3'-untranslated region (3'-UTR) of the human Cox-2 gene was characterized. Deletion of the distal region of the 3'-UTR strongly inhibited basal mRNA turnover, suggesting that this region contains mRNA instability determinants. However, deletion of the proximal highly-conserved region (CR1: 6082-6198) resulted in increased basal turnover, indicating that it determines mRNA stability. All of the 3'-UTR constructs conferred IL-1-induced stabilization but not dexamethasone-induced down-regulation. Thus, distinct regions of the 3'-UTR of the Cox-2 transcript are involved in the regulation of basal and cytokine-induced mRNA metabolism.

[Investigation of C1R gene frequencies in three Han populations in China]

To reveal the C1R polymorphism in Chinese, three Han populations in Guangzhou (101 samples), Jilin (105 samples) and Chengdu (111 samples) were investigated with a technique using PAGIF followed by immunoblotting. The results showed in Chengdu the C1R * 1 = 0.5676, C1R * 2 = 0.3424 and C1R * 5 = 0.0856, in Guangzhou C1R * 1 = 0.5248, C1R * 2 = 0.2663 and C1R * 5 = 0.1089, and in Jilin C1R * 1 = 0.5381, C1R * 2 = 0.2619 and C1R * 5 = 0.1714. Three rare genes C1R * 6, C1R * 7 and C1R * 8 were found in the investigation. These indicate that the frequency of C1R * 2 is elevated from north to south which may imply a geographic cline in this locus. The cumulated heterogeneity of C1R in Han population is 61.5% which means that this polymorphic system is useful in anthropolgy as well as in forensic science.

[Genetic polymorphism of antithrombin III in five Chinese populations]

The genetic polymorphisms of antithrombin III (AT III) in 5 Chinese populations were studied by isoelectric focusing on polyacrylamide gels followed by immunoblotting. The products of two alleles at the antithrombin III locus together with 1 AT III anodic variant and 3 cathode variants were observed. The results revealed that the predominant allele of AT III blood group system in Chinese populations was AT III *1, with frequencies between 0.9773-0.9850. Frequencies of AT III *2 ranged from 0.0091 to 0.0169. These results indicate that the polymorphic information content of AT III blood group system in Chinese populations is limited.

[Simultaneous phenotyping of proteins with various pHs by complex IEF and its application in forensic haemogenetics]

We have developed a new technique of complex isoelectric focusing (IEF) by which various proteins with different pHs can be detected out in polyacrylamide gels containing ampholytes with different pH ranges at the same time. The success of phenotyping 12 human proteins by this technique proved it was reliable and efficient. The cumulative Epp and the cumulative Dp reached 0.9 and 0.9999 respectively. It provides a new approach to analysis of genetic markers in the field of forensic haemogenetics.

A study of polymorphism of antithrombin III at the level of both protein and DNA in a Chinese population

The protein and DNA polymorphisms of human antithrombin III (ATIII) were studied by isoelectric focusing (IEF) and PCR techniques in a Chinese population sample (n = 51). Products of two alleles within the coding region of the ATIII locus were observed by IEF. The allele frequencies were: ATIII*1 = 0.9608, ATIII*2 = 0.0392. The PCR analysis of the fragment length polymorphism (FLP) for the ATIII 5' locus disclosed two alleles. Their frequencies were: ATIII5'*1 = 0.4118, ATIII 5'*2 = 0.5882. An association analysis between these two ATIII polymorphisms revealed the incompatibility between the ATIII 5'FLP and the ATIII IEF variants, indicating that the ATIII 5' FLP is not responsible for ATIII variants.

[The sandwich enzyme-linked immunoabsorbent assay of serum transferrin receptor by using monoclonal and polyclonal antibodies]

The human placenta transferrin receptor was purified in the form of transferrin-transferrin receptor complex (Tf-TfR), and a monospecific polyclonal antibody against TfR was developed by a Tf-coupled Sepharose 4B affinity chromatography to remove the anti-Tf components in the antiserum. A sandwich enzyme-linked immunoabsorbent assay (ELISA) was established for measuring serum transferrin receptor (sTfR) by using monoclonal antibody OKT9 and monospecific polyclonal antibody. This method is simple, specific and sensitive and has a good accuracy. The measurement of sTfR showed that the level of normal children was 4.54 +/- 1.08 mg/L. There were increased levels of sTfR in patients with severe iron deficiency anemia and those with hemolytic anemia (13.92 +/- 4.45 mg/L and 9.94 +/- 3.22 mg/L, respectively). In patients with aplastic anemia, the level was decreased (2.06 +/- 0.82 mg/L). These results indicate that the sTfR measurement has a differential significance for diagnoses of various anemia.

[Genetic polymorphism of properdin factor B in the Han population in Chengdu, China]

The genetic polymorphism of properdin factor B(Bf) was first investigated in the Han population in Chengdu by isoelectrofocusing and immunofixation. The results revealed BfSS (129 cases), BfFS (48 cases) and BfFF (9 cases). No Bf variants were noted in this study. The allele frequencies were: Bf * S 0.8226, Bf * F 0.1774.

[Application of ORM1 phenotyping in forensic science]

ORM1 is an important genetic marker for both parentage testing and personal identification in forensic science. We have examined the ORM1 phenotypes in the human serum and dried bloodstains using the ULPAGIF method. ORM1 phenotypes were successfully demonstrated from dried bloodstains stored at 4 degrees C and room temperature for up to twenty-four weeks. In bloodstains stored at 37 degrees C, the 100% of ORM1 phenotyping was no longer possible after 12 weeks. We examined 9 bloodstains stored at room temperature for one, two and three years, respectively. For the one-year-old bloodstains, all of the samples could be phenotyped correctly, for the two-year-old bloodstains 8 out of the 9 and for the three-year-old bloodstains 7 out of the 9 samples could be phenotyped correctly. The results have indicated that ORM1 is relatively stable, for it is tolerable toward high temperature and long duration. It was suggested that the bloodstains should be ultrasonicated before ULPAGIF, because the ultrasonication could elevate the detectable rate of ORM1 phenotypes from bloodstains. ORM1 phenotypes was performed in five disputed parentage cases. One of the alleged fathers was excluded.

[The influence of prostate-specific antigen p30 on human fertility]

The influence of prostate-specific antigen p30 on human fertility was studied with purified p30, domestic anti-p30 monoclonal and polyclonal antibodies. The results showed that the anti-p30 antibody presented in human serum had no negative effect upon human fertility and the anti-p30 antibody produced by heteroimmunization did not interfere with the process of human fertility in vitro. All these imply that it is unsuitable to recommend p30 as a contraceptive vaccine antigen.

[Subtyping of PiM in human serum and semen by modified isoelectric focusing]

An isoelectric focusing of Pi pretreated with neuraminidase is reported. Subtyping of PiM in human semen was successfully carried out for the first time. This has provided a new approach for individual identification in sexual crime.

[Isolation and purification of alpha -1 acid glycoprotein from human sera]

Alpha-1 acid glycoprotein, also named orosomucoid (ORM), is a serum protein with genetic polymorphism. This paper describes a two-step procedure for purifying ORM from human sera. The procedure consists of both anion exchange chromatography on a DEAE-Sephadex-A50 column and affinity chromatography on a Reactive Blue 2-Sepharose CL-6B column. The purified ORM identified by polyacrylamide gel electrophoresis, SDS-polyacrylamide gradient gel electrophoresis, immunoelectrophoresis and immunodiffusion was homogeneous and reacted specifically with a commercial anti-ORM serum (Sigma). The molecular weight of the purified ORM was about 41 kd.

A study of the genetic polymorphism of human inter-alpha-trypsin-inhibitor (ITI) in the Han population, Chengdu, China

Phenotypes of inter-alpha-trypsin-inhibitor (ITI) have been determined by isoelectric focusing on polyacrylamide gels followed by immunofixation. The phenotype frequencies of ITI in the Han population in Chengdu, P.R. China have been investigated using this method. In addition, family studies have been conducted in 21 families. The results show that ITI is polymorphic in the Han population in Chengdu, China. The allele frequencies are as follows: ITI*1 = 0.5763. ITI*2 = 0.4107, ITI*3 = 0.0130. ITI is thus a new and promising genetic marker that can be used in the field of forensic haematogenetics.

CT and pathological study on radiofrequency-induced lesion in cat thalamus

In order to observe the postoperative focal changes caused by radiofrequency lesions in the ventrolateral nucleus of the thalamus in stereotactic treatment of Parkinson's disease, similar lesions were produced in cat. The CT features and their correlative pathologic changes at different intervals were divided into three types, four stages and three zones. The degree of susceptibility of nervous tissue to radiofrequency, repair characteristics and the mechanism of CT enhancement are discussed in light of the pathologic changes.

Genetic polymorphisms of alpha-2-HS-glycoprotein, group-specific component and orosomucoid in the Han population, Chengdu, China

The Han population in Chengdu, China, was investigated for genetic polymorphisms of alpha-2-HS-glycoprotein (A2HS), group-specific component (GC) and orosomucoid (ORM) using isoelectric focusing followed by immunofixation. The allele frequencies were: A2HS*1 = 0.6958,A2HS*2 = 0.3042, GC*1F = 0.4021, GC*1S = 0.3182, GC*2 = 0.2745, GC*1A = 0.0052, ORM1*F1 = 0.7028, ORM1*S = 0.2762, ORM1*F2 = 0.0210, ORM2*A = 0.9965, ORM2*Var = 0.0035.

[Genetic polymorphism of alpha 2HS-glycoprotein in the Han population in Chengdu]

The distribution of alpha 2HS-glycoprotein (AHSG) phenotype frequencies in the Han population in Chengdu was studied using polyacrylamide gel isoelectric focusing followed by immunofixation with rabbit anti-human AHSG serum. Two hundred eighty-six serum samples collected at random from unrelated individuals were phenotyped for AHSG. The distribution of AHSG phenotype frequencies was found to be AHSG 1 = 47.20%, AHSG 2 = 8.04% and AHSG 2 - 1 = 44.76%. The observed numbers agreed well with the expected numbers calculated on the basis of the Hardy-Weinberg equilibrium. The allele frequencies were estimated to be AHSG.1 = 0.6958 and AHSG.2 = 0.3042. The discrimination probability of AHSG is 0.5704 and the exclusion probability of parentage 0.1669.