Case report: One case of acute myeloid leukemia M3 with atypical morphology.

Acute promyelocytic leukemia (APL) is a type of acute myeloid leukemia. About 2% of APL is characterized by atypical rearrangements. Here we reported one APL case with atypical manifestations and morphology. A 35-year-old woman patient, mainly due to fatigue, poor appetite for over 10 days and intermittent fever for 3 days. combined with the results of flow cytometry, fusion gene and chromosome, the patient was diagnosed as AML-M3 with atypical morphology. Double induction therapy with retinoic acid and arsenous acid was immediately administrated. Idarubicin was administrated on the 18th day. A re-examination was performed in the 5th week, both the blood routine test and myelogram showed normal results, and the fusion gene turned negative, indicating complete remission. When atypical morphology occurs, peripheral blood POX staining may be performed to check the abnormal cells. Flow cytometry, chromosome analysis, and fusion gene analysis are also required for further diagnosis.

Corrigendum: Detection and homology analysis of carbapenem resistant Acinetobacter baumannii resistance gene.

[This corrects the article DOI: 10.3389/fcimb.2022.987260.].

Detection and homology analysis of carbapenem resistant Acinetobacter baumannii resistance gene.

Objective: To explore the carrying status and homology of carbapenem resistant Acinetobacter baumannii (CRAB) in our hospital. Methods: From January 2015 to December 2017, 52 strains of acinetobacter baumannii isolated from the bacteria room of the clinical laboratory of Baogang hospital in Inner Mongolia were selected as the research object. K-B disk diffusion method and Vitek-2 were used to determine the drug sensitivity of Acinetobacter baumannii. The drug resistance gene was detected by polymerase chain reaction (PCR) and its homology was analyzed by pulsed field gel electrophoresis (PFGE). Results: Except for Cefoperazone/sulbactam, other antibiotics were resistant to ab. The detection rate of drug resistance gene class C ß-lactamases (ADC) was 100%, and the higher detection rates of other drug resistance genes were class D ß-lactamases (OXA)-51 (36 strains, 90.0%),disinfectant gene qacE△1-sull (32 strains, 80.0%), and klebsiella pneumoniae carbapenemase (KPC) gene was not detected. 2-8 drug resistance genes were detected in each CRAB strain, and the strains with 6 drug resistance genes were the most (15 strains, 37.5%); Among the detected drug-resistant gene combinations, ADC+OXA-23 + OXA-51 gene was detected at the same time (29 strains, 72.5%), followed by ADC+ intl1 + qacE △ 1-sull gene (26 strains, 65.0%), ADC + qacE △ 1-sull + ant (3 '') -i gene (19 strains, 47.5%), and 11 strains (27.5%). There were 19 different types in PFGE homology test, each type was 1-9 strains, including 9 strains of A5 type and 8 strains of A18 type, mainly from intensive care unit. Conclusion: CRAB in the hospital is highly resistant to common clinical antibiotics. OXA-23 and OXA-51 genes are most likely to be the main factors causing drug resistance of Acinetobacter baumannii in the hospital. Homology analysis showed that there was CRAB nosocomial infection transmission in different wards of the hospital.

Construction of a fully synthetic human scFv antibody library with CDR3 regions randomized by a split-mix-split method and its application.

The randomization scheme of hypervariable region takes crucial role in construction of a synthetic antibody library. The codon bias and inevitable 'stop' codon of conventional 'NNK' and 'NNS' codons limit their applications. Here we report a split-mix-split DNA synthesis method that can control over the amino acid composition and distribution of randomized sequences effectually. A fully synthetic human antibody library with a diversity of 1.56 x 10(9) was successfully generated with complementarity determining region 3 (CDR3) randomized by this strategy. Sequencing analysis indicated that >60% of colonies had completely correct scFv genes and the amino acid composition and distribution were designed well in accordance. The utility was demonstrated by screening of scFv clones against BHL (anti-CD3 x anti-ovarian carcinoma bispecific antibody). These results proved the feasibility of the split-mix-split DNA randomization strategy in library construction and site-directed mutagenesis.

Structure-function relations of carbohydrates by neoglycolipid arrays.

The work presented herein is a new noncovalent glycoarray assembly method for microplates created by simply mixing together a carbohydrate and a tetradecylamine. alpha-D-Mannopyranoside, alpha-D-glucopyranoside, and alpha-D-galactopyranoside were utilized in model studies and product formations were detected by lectin binding. The method can be extended to study the steric hindrance effect of carbohydrate-protein interactions, namely the structure-function relations of carbohydrates.

[A preliminary study of the structure prediction and expression of SARS-CoV spike protein].

In this study, the encoding sequences of SARS-CoV spike protein were analyzed by bioinformatics methods, the structural characteristics and functions were forecasted based on available data. It suggests that the fragment of spike glycoprotein (S401-659) may be crucial for viral attachment and may be a major immunodominant epitope. Then the fragment was amplified and subcloned into expression vector pET28a(+) and pPIC9K. These two plasmids pET28a(+)-S and pPIC9K-S were transformed to E.coli strain BL21(DE3)-star and Pichia pastoris, respectively. SDS-PAGE and Western blot analysis showed that the recombinant protein was successfully expressed. The denatured inclusion bodies were purified with Ni-NTA chelate agarose and its purity can reach 90%.

Production of soluble and functional engineered antibodies in Escherichia coli improved by FkpA.

Overproduction of genetically engineered antibodies, such as single-chain antibodies (scAbs) in Escherichia coli often results in insoluble and inactive products known as inclusion bodies. We now report that fusion or co-expression of FkpA, the E. coli periplasmic peptidyl-prolyl-isomerase with chaperone activity, substantially improves soluble and functional expression of scAbs. Anti-human bladder carcinoma scAb (PG) and anti-human CD3 x anti-human ovarian carcinoma-bispecific scAb (BH1) were fused with FkpA on the pTMF-based plasmid and expressed in E. coli. More than half of the amount of each expressed fusion protein FkpA-PG or FkpA-BH1 was soluble. In addition, the fusion protein cellulose-binding domain from Cellulomonas fimi (CBD)-PG and anti-human CD3 x anti-human CD28 x anti-human ovarian carcinoma-trispecific scAb (TRI) fused to the pelB (a signal peptide from pectate lysase B of a Bacillus sp.) signal sequence were co-expressed with FkpA under the control of the T7 promoter. A substantial portion of the co-expressed CBD-PG or TRI was soluble. Furthermore, PG, BH1, and TRI were biologically active as judged by ELISA and in vitro cytotoxicity assay. These results suggest that overexpression of FkpA should be useful in expressing heterologous proteins in E. coli.

A new approach for rapidly reshaping single-chain antibody in vitro by combining DNA shuffling with ribosome display.

Antibody reshaping is an effective way to reduce the immunogenicity while maintaining or improving the affinity of murine antibodies. This paper describe a new in vitro approach for rapidly reshaping murine antibodies by combining DNA shuffling with ribosome display. With the new method, a reshaping anti-4-1BB single-chain antibody (scFv), Re-4B4-1 scFv, which bound to its antigen (4-1BB) specifically and strongly, was selected from a reshaping library. These results proved definitely the feasibility of the new designed approach for antibody reshaping.

A new recombinant single chain trispecific antibody recruits T lymphocytes to kill CEA (carcinoma embryonic antigen) positive tumor cells in vitro efficiently.

Anti-tumor associated antigen (TAA).CD3.CD28 trispecific antibody(TsAb) is able to provide two signals for fully and continuously activation of T lymphocytes and recruit them around tumor cells, presenting an attractive concept in tumor immunotherapy. Here, a new single chain trispecific antibody (scTsAb), named CEA-scTsAb, was constructed by fusion of anti-CEA (Carcinoma Embryonic Antigen) single chain antibody (scFv), anti-CD3 scFv and anti-CD28 VH, spaced by polypeptide interlinkers taken from the fragment of constant region (FC) of human IgG and human serum albumin (HSA). It was expressed in Escherichia coli at low temperature (30 degrees C) with up to 50% of the antibody being present in soluble form. After one step of DEAE anion chromatography, the soluble product was sufficiently pure for further in vitro activity assays. First, it was proved that CEA-scTsAb could recognize three antigens (CEA, CD28 and Jurkat cell membrane antigen) specifically and could distinguish antigen positive cells from antigen negative cells in vitro. Then fresh PBMC (peripheral blood mononuclear cells), without being pre-treated by co-stimulatory reagents, such as IL-2 or CD28 mAb, were used as effector cells to test their ability to mediate tumor specific cytolysis of CEA-positive tumor cells, SW1116. It was found by photomicrography that T lymphocytes were attracted to SW1116 cells in the presence of CEA-scTsAb, which resulted in effective cytolysis of tumor cells. As shown by MTT assay, the efficacy of tumor specific cytolysis mediated by CEA-scTsAb related to both the quantity and activation of PBMC. At an effector cells/target cells ratio (E/T) of 5, it was proved by dual-color FACS with propidium iodide (PI) and FITC-annexin V that both necrosis and apoptosis of tumor cells were causes of tumor specific cytolysis. In summary, a new single chain trispecific (CEA x CD3 x CD28) antibody was constructed and characterized carefully in this paper and was found to possess functions: (i) to activate T lymphocytes independently of additional co-stimulatory signal, (ii) to attract activated T lymphocytes around CEA-positive tumor cells, (iii) to attack CEA-positive tumor cells with recruited T lymphocytes. Because it recognizes a widely distributed tumor antigen (CEA), with moderate molecular weight (about 75 kDa) and a simple production procedure, and is able to mediate a high level of tumor specific cytolysis without any additional co-stimulating reagents, CEA-scTsAb is very promising for the task of immunotherapy in future.

Soluble expression of recombinant human secondary lymphoid chemokine (SLC) in E. coli and research on its in vitro and in vivo bioactivity.

Secondary lymphoid tissue chemokine (SLC) is a CC chemokine that plays an important role in leukocytes homing to lymphoid tissues. The ability of SLC to co-localize both T cells and dendritic cells formed the rationale to evaluate its utility in cancer immunotherapy. The in vivo antitumor effect of murine SLC (mSLC) has been well documented, but little is known about that of human SLC (hSLC). To investigate the antitumor efficiency in vivo of hSLC, the hSLC gene was artificially synthesized and induced to express as a soluble form in Escherichia coli. After purification, the purity of the recombinant human SLC (rhSLC) protein was above 95% by SDS-PAGE analysis. The K(d) of rhSLC binding to peripheral blood lymphocytes (PBLs) was 0.2186 +/- 0.02675 microM as assessed by FACS, and the maximal chemotactic index of rhSLC was 9.49 at 100 nM as assessed by in vitro chemotaxis assay. Then genomic sequences of hSLC and mSLC, and of human CCR7 (hCCR7) and murine CCR7 (mCCR7), the receptor for SLC, were aligned. It was found that hSLC and mSLC share 70.72% identity and hCCR7 and mCCR7share 86.77% identity. Furthermore, we found that rhSLC could chemoattract murine peripheral blood mononuclear cells (PBMCs) in vitro. On the basis of these facts, immune competent mice inoculated with S180 sarcoma cells were chosen as an in vivo model. Intratumoral injections of rhSLC inhibited tumor growth and increased survival. These findings suggest that, despite its incapability to bind to either human or murine CXCR3, which is related to angiostasis, rhSLC can induce an antitumor response in vivo by another route. This report proves that rhSLC has a potent tumor-inhibition ability that makes it a promising candidate agent in cancer immunotherapy.

Functional analysis of the ver gene using antisense transgenic wheat.

The function of ver203, a gene related to vernalization in winter wheat, was investigated by expression of a complementary DNA as an antisense RNA in transgenic plants. A verc203:gus fusion-expression plasmid was constructed in pBI221, which contains a CaMV (cauliflower mosaic virus) 35S-promoter, a gus gene and a nos terminator. The construct was then introduced into the plant by the pollen-tube pathway. The results showed that heading was strongly inhibited in 6 of 326 vernalized antisense transgenic winter wheat plants, until both the vernalized control winter wheat and sense transgenic plants ripened. The hybridization analysis of DNA, amplification of the insert DNA sequences with PCR, northern blot analysis with double- and single-stranded probes, and detection of GUS activity by X-gluc assay gave strong positive results. This suggests that the VER203 protein plays an important role in controlling heading and flower development in winter wheat.

A new model of trispecific antibody resulting the cytotoxicity directed against tumor cells.

Bispecific antibodies (BsAb) with specificity to both tumor cells and CD3 molecule were believed to be promising immunological tools for the therapy with minimal residual diseases by activating cytotoxic T cells. However, without costimulatory molecule CD28, the activated T cells tended to apoptosis. In order to kill tumor cells more efficiently, a recombinant multifunctional single-chain trispecific antibody (scTsAb), which contains anti-ovarian carcinoma (OC) scFv, anti-CD3 scFv and VH domain of anti-CD28 antibody, was constructed and expressed in E. coli BL21 Star strain. The scTsAb showed strong binding avidities to membrane antigen of SK-OV-3 cell, CD3 molecule on Jurkat cell, and recombinant CD28 antigen. It was further demonstrated that this scTsAb could activate peripheral blood T cells to elicit strong cytotoxicity against SK-OV-3 cells. This new type of recombinant scFv antibody set up a new technological platform for T cells based immunotherapy against cancer, especially with the failure on MHC antigen presentation or absence of costimulating signal.

[An efficient approach to the synthesis of a high-quality random peptide repertoire].

During the construction of a random peptide repertoire using degenerate models, unexpected amino acids or stop codons are almost unavoidable. To conquer this shortcoming, a new split-mix-split method of oligonucleotide synthesis was developed. A 13-amino acids random peptide library had been constructed by using this method. The sequencing results of 16 clones indicated that neither stop codon nor codon for cysteine appeared as designed. The occurrence rations of 19 amino acids were also calculated and no obvious amino acid bias had been observed. By using this method, the type and quantity of amino acid at certain position of a peptide could be controlled well, so this split-mix-split method, combined with degenerate could meet the needs of a high diversity random peptide library.

A method for constructing reshaping single-domain antibody.

The aim of this research was to demonstrate a novel and practical method for constructing reshaping Single-domain antibodies. Different from other methods, our method does not need to model the configuration of antibodies with specific sequences to determine the sequences of human acceptor FRs and then determine which amino acid residues in human acceptor FRs should be substituted. Most importantly, reshaping and enhancing the antigen binding affinity shared one procedure at the same time. Using this method, the reshaping anti-CD28 single-domain antibodies were constructed. According to the amino acid sequence of a mouse anti-human CD28 monoclonal antibody VH, two most homologous sequences of human antibodies were selected from GenBank and one of them was used as a main framework region for constructing the reshaping antibody. Before the original mouse antibody CDRs were inserted into the human acceptor FRs, some amino acid residues which were different from those of the original mouse antibody in the corresponding positions of the human acceptor FRs were determined or alternatively mutated by their conservative properties in Kabat classification. When the synthesized nucleotide fragments in different length were spliced by overlap PCR into the entire reshaping genes, Taq DNA polymerase and high Mg2+ concentration were used to introduce more mutation in FRs and CDRs randomly. A phage library was constructed using these PCR products and several reshaping Single-domain antibodies with high antigen binding affinity were selected after three rounds of panning. Two of them were expressed in E. coli BL21 (DE3). The antigen-binding affinity of refolded proteins was still in a high level measured by ELISA. These results suggested that this method was feasible and efficient for constructing reshaping Single-domain antibodies.

[Construction and expression of single chain Fv gene of anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum].

OBJECTIVE: To construct single chain Fv (scFv) gene of anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum. METHODS: The heavy and light chain variable region genes of anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum were inserted into two corresponding sites of expression vector pTHA90, and a scFv gene was constructed with a short peptide (Gly4Ser)3 linker gene. The recombinants were determined by digesting with XhoI/SpeI, XbaI/EcoRI and XhoI/EcoRI, and then were introduced into E. coli Top10. The antigen binding activity of expressed product was detected with ELISA. RESULTS: The recombinants were determined by digesting with endonucleases and expected bands were identified. The value of expressed scFv was 3 times higher than negative control by ELISA(OD492 = 1.06). CONCLUSION: The scFv gene of anti-idiotypic monoclonal antibody NP30 of Schistosoma japonicum was successfully cloned, and the expressed scFv fragment could interact specifically with antigen NP48.

Testis-specific Fank1 gene in knockdown mice produces oligospermia via apoptosis.

Fank1 is exclusively expressed in the testis from the meiosis phase to the haploid phase of spermatogenesis. In this study, we examined the function of Fank1 by establishing a Fank1-knockdown transgenic mouse model. The apoptotic statuses of the testes of the transgenic mice were tested using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. The FANK1 consensus DNA-binding sequence was identified using cyclic amplification of sequence target (CAST) analysis. Differentially expressed genes were examined using microarray analysis. A reduction in sperm number and an increase in apoptotic spermatocytes were observed in Fank1-knockdown mice, and the apoptotic cells were found to be primarily spermatogonia and spermatocytes. The CAST results demonstrated that the consensus DNA-binding sequence was AAAAAG, in which the percentage occurrence of each base at each position ranged from 55 to 86%. This sequence was present in the promoter regions of 10 differentially expressed genes that were examined using microarray analysis. In total, 17 genes were differentially expressed with changes in their expression levels greater than twofold. The abnormal expression of Fank1 target genes that were regulated directly or indirectly by Fank1 reduced the number of sperm in the knockdown mice. Thus, FANK1 may play a pivotal role in spermatogenesis as a transcription factor.

[Cloning and expression in Escherichia coli of secondary lymphoid-tissue chemokine (SLC) gene].

Secondary lymphoid-tissue chemokine (SLC) is a type of CC chemokine identified by searching the Expressed Sequence Tag (EST) database. The full-length SLC gene was synthesized based on human SLC sequence using SOE-PCR. The sequenced SLC gene was cloned into expression vector pTMF and pALM, which used to transform Escherichia coli. Then the E. coli was cultured and induced according to protocol. The expressed target protein was identified by Western blotting. The target protein was expressed as soluble protein as well as inclusion bodies, the ratio of these two forms target protein varied with the difference conditions of culture and induction. The target protein was purified with the methods of nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity chromatography. The results of electrophoresis of the purified target protein showed that the molecular weight was larger than the predicted molecular weight.

[Escherichia coli disulfide-forming related proteins: structures, functions and their application in gene engineering for expressing heterologous proteins in Escherichia coli].

The formation of disulfide bonds in secreted proteins of E. coli is a synergetic process depending on a series of Dsb proteins containing DsbA, DsbB, DsbC, DsbD, DsbE and DsbG. DsbA functions as an oxidant to form a disulfide bond between two -SH- in vivo and DsbB reactivates DsbA by reoxidizing it. Both DsbC and DsbG, two periplasmic proteins with isomerase activity, can correct mis-paired disulfide bonds introduced by DsbA although they recognize different substrates. DsbD, an inner membrane protein, plays a role in reducing DsbC and DsbG in vivo. It is regarded that DsbE has the similar function with DsbD. All DsbA, DsbC and DsbG have chaperone activity besides involving in the formation of disulfide bonds. Furthermore, their chaperone activity can promote the formation of protein disulfide bonds. There are a few reports dealing with soluble expression of heterologous proteins containing disulfide bonds assisted by DsbA and DsbC in E. coli. So far there has been no reports about the soluble expression of heterologous proteins promoted by DsbG. Our experiments first demonstrated that both DsbC and DsbG can improve the expression of single chain antibodies as soluble and functional forms in E. coli, and DsbG has additive effects with DsbC.

[Protein splicing and its application].

Protein splicing is a newly discovered posttranslational editing process that removes an internal protein fragment from the protein precursor. During the splicing process the internal protein fragment, intein, triggered the self-excision from the precursor protein and the concomitant ligation of the flanking protein fragments, exteins. The self-catalysis requires neither auxiliary enzymes nor cofactors and only involves four intramolecular reactions. A number of key catalytic residues in inteins and flanking fragments have been identified, which led to the development of the protein splicing process as a protein engineering tool. Controllable cleavage of the peptide bond at either the N or the C terminus of an intein has allowed the design of novel strategies for manipulation of protein and peptides. Affinity purification of recombinant proteins can be facilitated by fusion the target protein with an intein. The fusion also creates C-terminal thioester, which expands the scope of chemical ligation in protein. Inteins can be engineered in a "split and inverted" configuration to form a cyclic polypeptide consisting of the sequence linking two intein subdomains. This article summarizes the recent advance in the mechanism of protein splicing and its applications in protein purification, protein ligation and protein cyclization.