[The value of minimal residual disease and IKZF1 deletion for predicting prognosis in adult patients with B-cell acute lymphoblastic leukemia].

Objective: To reassess the prognostic value of minimal residual disease (MRD) and IKZF1 gene deletions in adults with B-cell acute lymphoblastic leukemia (B-ALL) who received pediatric-specific chemotherapy regimens during the Nanfang Hospital PDT-ALL-2016 trial. Methods: We retrospectively analyzed the prognosis of 149 adult patients with B-ALL who were admitted to Nanfang Hospital from January 2016 to September 2020. Prognostic factors were identified using Cox regression models. Results: The complete remission rate was 93.2% in 149 patients, with a 5-year overall survival (OS) rate of (54.3±5.0) % and a cumulative incidence of relapse (CIR) of (47.5±5.2) %. The Cox regression analysis revealed that MRD positivity at day 45 (MRD(3)) after induction therapy was independently associated with relapse risk (HR=2.535, 95%CI 1.122-5.728, P=0.025). Deletion of IKZF1 gene was independently associated with mortality risk (HR=1.869, 95%CI 1.034-3.379, P=0.039). Based on MRD(3) and IKZF1 gene status, we categorized adult patients with B-ALL into the low-risk (MRD(3)-negative and IKZF1 gene deletion-negative) and high-risk (MRD(3)-positive and/or IKZF1 gene wild type) groups. The 5-year OS and CIR rates were (45.5±6.0) % vs (69.4±8.6) % (P<0.001) and (61.6±8.3) % vs (25.5±6.5) % (P<0.001), respectively, in the high-risk and low-risk groups, respectively. The multivariate analysis showed that the high-risk group was an independent risk factor for OS (HR=3.937, 95%CI 1.975-7.850, P<0.001) and CIR (HR=4.037, 95%CI 2.095-7.778, P<0.001) . Conclusion: The combined use of MRD and IKZF1 gene in prognostic stratification can improve clinical outcome prediction in adult patients with B-ALL, helping to guide their treatment.

[A single-center study on the distribution and antibiotic resistance of pathogens causing bloodstream infection in patients with hematological malignancies].

Objective: To study the incidence of bloodstream infections, pathogen distribution, and antibiotic resistance profile in patients with hematological malignancies. Methods: From January 2018 to December 2021, we retrospectively analyzed the clinical characteristics, pathogen distribution, and antibiotic resistance profiles of patients with malignant hematological diseases and bloodstream infections in the Department of Hematology, Nanfang Hospital, Southern Medical University. Results: A total of 582 incidences of bloodstream infections occurred in 22,717 inpatients. From 2018 to 2021, the incidence rates of bloodstream infections were 2.79%, 2.99%, 2.79%, and 2.02%, respectively. Five hundred ninety-nine types of bacteria were recovered from blood cultures, with 487 (81.3%) gram-negative bacteria, such as Klebsiella pneumonia, Escherichia coli, and Pseudomonas aeruginosa. Eighty-one (13.5%) were gram-positive bacteria, primarily Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecium, whereas the remaining 31 (5.2%) were fungi. Enterobacteriaceae resistance to carbapenems, piperacillin/tazobactam, cefoperazone sodium/sulbactam, and tigecycline were 11.0%, 15.3%, 15.4%, and 3.3%, with a descending trend year on year. Non-fermenters tolerated piperacillin/tazobactam, cefoperazone sodium/sulbactam, and quinolones at 29.6%, 13.3%, and 21.7%, respectively. However, only two gram-positive bacteria isolates were shown to be resistant to glycopeptide antibiotics. Conclusions: Bloodstream pathogens in hematological malignancies were broadly dispersed, most of which were gram-negative bacteria. Antibiotic resistance rates vary greatly between species. Our research serves as a valuable resource for the selection of empirical antibiotics.

[Prognostic significance of IKZF1 gene deletions in patients with B-cell acute lymphoblastic leukemia].

Objective: This study aimed to investigate the prognostic significance of IKZF1 gene deletion in patients with acute B lymphoblastic leukemia (B-ALL) . Methods: The clinical data of 142 patients with B-ALL diagnosed in Nanfang Hospital between March 2016 and September 2019 were analyzed. Results: IKZF1 deletion was found in 36.0% of the 142 patients with B-ALL, whereas exon 4-7 deletion was found in 44.0% . White blood cell counts were higher in patients with the IKZF1 deletion (52.0% and 28.3% , P=0.005) ; these patients also experienced worse effects of mid-term induction therapy (40.0% and 70.7% , P<0.001) and had a higher proportion of Philadelphia chromosome-positive (52.0% and 21.7% , respectively, P<0.001) . Univariate analysis revealed that the 3-year overall survival rate (OS) and event-free survival rate (EFS) in the IKZF1 deletion group were significantly lower than the IKZF1 wild-type group [ (37.1±7.3) % vs (54.7±5.4) % , (51.8±7.9) % vs (73.9±4.7) % ; P=0.025, 0.013, respectively]. Multivariable analysis showed that harboring IKZF1 deletion was an adverse factor of EFS and OS (HR=1.744, 2.036; P=0.022, 0.020, respectively) . Furthermore, the IKZF1 deletion/chemotherapy group had significantly lower 3-year OS, EFS, and disease-free survival rates than other subgroups. In the IKZF1 deletion cohort, allo-hematopoietic stem cell transplantation (HSCT) significantly improved OS and EFS compared to non-allo-HSCT[ (67.9±10.4) % vs (31.9±11.0) % , (46.6±10.5) % vs (26.7±9.7) % ; P=0.005, 0.026, respectively]. Conclusion: Pediatric-inspired chemotherapy was unable to completely reverse the negative effect of IKZF1 deletion on prognosis. Pediatric-inspired regimen therapy combined with allo-HSCT, in contrast, significantly improved the overall prognosis of IKZF1 deletion B-ALL.

[Diagnosis of adult Philadelphia chromosome-like acute lymphoblastic leukemia by fluorescence in situ hybridization].

Objective: To establish a screening system of adult Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) by fluorescence in situ hybridization (FISH) . Method: Based on the genetic characteristics of Ph-like ALL, FISH probes were designed for ABL1, ABL2, JAK2, EPOR, CRLF2, CSF1R, PDGFRB, and P2RY8 gene breakpoints, which were used to screen Ph-like ALL in B-ALL patients without BCR-ABL1, ETV6-RUNX1, MLL, and E2A gene arrangement. Furthermore, it was analyzed in combination with flow immunophenotype, next-generation sequencing for targeted gene mutations, and RNA sequencing (RNA-seq) . Results: A total of 189 adult B-ALL patients diagnosed in Nanfang Hospital from January 2016 to April 2019 were enrolled in this study. Using FISH and/or PCR, BCR-ABL1, ETV6-RUNX1, MLL, or E2A arrangement was detected in 83 of them, and Ph-like ALL was detected by FISH in the other 106, resulting in the presence of typical gene arrangements of Ph-like ALL in 12 patients (11.3% , 12/106) . Validated by RNA-seq, the sensitivity and specificity of FISH for Ph-like ALL were 71.4% and 95.8% , respectively. After further analysis with immunophenotype, targeted gene mutations, and RNA-seq, 14 (13.2% , 14/106) were diagnosed with Ph-like ALL. Conclusion: This data shows high specificity of FISH for identification of Ph-like ALL and combining immunophenotype and sequencing technology can improve the diagnostic system.

[The effect of booster dose vaccination 21- to 32-years after primary vaccination with hepatitis B vaccine in the population born from 1986 to 1996 in Zhengding County of Hebei Province].

Objective: Aanalysis the effect of booster one dose of hepatitis B vaccine after 21-32 years of primary immunization in Zhengding Country of Hebei Province. Methods: A total of 322 participants who were born between 1986 and 1996, received a full course of primary vaccination with plasma-derived hepatitis B vaccine (HepB), had no experience with booster vaccination, were HBsAg, anti-HBcnegative, had anti-HBs<10 mIU/ml, completed the booster and had laboratory results were enrolled between August 2017 to February 2018. A simple random method was uesd to randomly assigned 322 subjects to two groups, receiving a booster dose of HepB derived from either Saccharomyces cerevisiae ï¼»HepB (SC), (151 cases)ï¼½ or Chinese hamster ovary-derived HepB ï¼»HepB (CHO), (171 cases)ï¼½, the dose was 20 µg. Blood samples were collected 30 days after boosting and quantitatively tested for the geometric mean concentration (GMC) of anti-HBs to assess immunological effect. The related influencing factors of GMC and seroconversion rates of anti-HBs were analyzed by multiple linear regression and multivariate logistic regression models. Results: The 266 subjects (82.61%) had anti-HBs≥ 10 mIU/ml, and GMC was (131.63±12.94) mIU/ml.The seroconversion rates of anti-HBs in the anti-HBs<2.5 mIU/ml group and 2.5-10 mIU/ml group were 74.54% (161 cases) and 99.06% (105 cases), respectively (P<0.001).The seroconversion rates of anti-HBs after one dose of HepB (CHO) was higher than that of one dose of HepB (SC), the seroconversion rates were 87.13% (149 cases) and 77.48% (117 cases), respectively (P=0.023). Participants boostered with HepB (CHO) was the factor influencing the effect of strengthening immunization compared with boostered with HepB (SC), and OR (95%CI) was 1.91 (1.02-3.56) (P=0.042).Compared with anti-HBs<2.5 mIU/ml, prebooster anti-HBs was between 2.5 mIU/ml and 10 mIU/ml was the related factor of seroconversion rates of anti-HBs after booster immunization, and OR (95%CI) was 36.15 (4.91-266.02) (P<0.001). Conclusion: Participants boostered withone dose of HepB had a good immune response. Pre-booster anti-HBs concentration and a variety of vaccine were related factors of immune response.

[Involvement of Src kinase in the down-regulation of ultra-rapid delayed rectifier K(+)current induced by tumor necrosis factor-α in cardiomyocytes].

Objective: To investigate whether inflammatory factor tumor necrosis factor-α (TNF-α) is involved in the electrical remodeling of cardiomyocytes by regulating ultra-rapid delayed rectifier K(+) current (I(kur)) and the role of Src kinase. Methods: H9c2 cells, embryonic cardiomyocytes of rat, were cultured in Dulbecco's modified Eagle's medium (DMEM) and atrium-derived HL-1 cells were cultured in Claycomb medium. Both H9c2 and HL-1 cells were cultured at 37 ℃ with 5% CO(2). Cells cultured in normal conditions without additional treatment served as control group. Experimental groups were treated with different concentration of TNF-α (25 or 50 or 100 ng/ml) for 24 hours. To study whether Src specific inhibitor PP1 could abrogate the effect of TNF-α, cells were pre-treated with 10 µmol/L PP1 for 1 hour, followed by TNF-α (100 ng/ml) for 24 hours. Western blot and the whole cell patch clamp technique were used to detect the protein expression of Kv1.5 and Src and I(kur) in each group. Results: (1) In H9c2 cells, high concentration of TNF-α treatment (100 ng/ml) significantly reduced the Kv1.5 protein expression compared with control group and TNF-α 25 ng/ml group (both P<0.05). Compared with control group, the expression of p-Src protein was higher in 25 ng/ml, 50 ng/ml, 100 ng/ml TNF-α group (all P<0.05), but there was no statistical difference in the expression of Src protein among groups (P>0.05). In addition, the current density of I(kur) was decreased in 50 ng/ml, 100 ng/ml TNF-α group (both P<0.05). Furthermore, the expression of Kv1.5 protein and the current density of I(kur) were increased in PP1+TNF-α group compared with TNF-α 100 ng/ml group (both P<0.05). There was no statistical difference in the expression of Kv1.5 protein and the current density of I(kur) between the control group and PP1+TNF-α group (both P>0.05). (2) In atrium-derived HL-1 cells, the expression of Kv1.5 protein was reduced in 100 ng/ml TNF-α group compared with control group and TNF-α 25 ng/ml group (both P<0.01). In addition, the expression of p-Src protein was increased in TNF-α 100 ng/ml group compared with control group (P<0.05), but there was no statistical difference in the protein expression of Src among groups (P>0.05). The expression of Kv1.5 protein was increased in PP1+TNF-α group compared with TNF-α 100 ng/ml group (P<0.05). Conclusion: TNF-α is involved in the pathogenesis of atrial fibrillation, probably via decreasing I(kur) current density in atrium-derived myocytes through the activation of Src kinase.

Study on the expression of Toll-like receptor 4 and matrix metalloproteinase-9 in patients with chronic obstructive pulmonary disease and their clinical significance.

OBJECTIVE: To investigate the expression of Toll-like receptor 4 (TLR4) and matrix metalloproteinase-9 (MMP-9) in patients with chronic obstructive pulmonary disease (COPD) and their clinical significance. PATIENTS AND METHODS: Paracancerous tissues from 48 patients with lung squamous cell carcinoma harvested during pulmonary lobectomy were studied. Twenty-four cases of COPD were chosen as the observation group and 24 cases of non-COPD as the control group. The degree of lung inflammation was observed; the ratio of the thickness of the wall to the external diameter of the pulmonary arterioles (WT%), and the ratio of the area of the wall to that of the pulmonary arterioles (WA%) were calculated. Immunohistochemistry was used to evaluate the expression of TLR4, MMP-9, and proliferating cell nuclear antigen (PCNA) in vascular smooth muscle cells, and the expressions were correlated with lung revascularization. RESULTS: (1) Compared with the non-COPD group, the degree of inflammatory cell infiltration, WA%, and WT% of the COPD group were significantly increased (p<0.05). Additionally, the expression of TLR4, MMP-9, and PCNA in vascular smooth muscle cells was significantly increased (p<0.05). (2) Correlative analysis revealed that the expression of TLR4 and MMP-9 had significant positive correlation with the degree of inflammatory cell infiltration, WA%, WT%, and PCNA expression (p<0.05). Multivariate regression analysis showed that, compared with the smoking index and inflammation score, TLR4 and MMP-9 expression were the strongest factors affecting the parameters of lung revascularization (WA% and WT%) (p<0.05). CONCLUSIONS: High expression of MMP-9 and TLR4 in patients with COPD may promote inflammatory cell infiltration, induce proliferation of smooth muscle cells, degrade extracellular matrix, and play an important role in lung revascularization.

[Clinical analysis of adult Philadelphia chromosome-positive acute lymphoblastic leukemia with p16 gene deletion].

Objective: To investigate the clinical implications of p16 gene deletion in adult Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) . Methods: Retrospective analysis of clinical, immunophenotypic, cytogenetics, molecular characteristics and prognosis of 80 newly diagnosed Ph(+) ALL patients with p16 deletion. Results: Of 80 adult Ph(+) ALL, the prevalence of p16 gene deletion was 31.3%. p16 gene deletion carriers frequently accompanied with high WBC counts (WBC≥30×10(9)/L) and CD20 expression. The incidence of complex chromosome abnormality in p16 gene deletion group was higher than that in non-deletion group, with alternations in chromosome 7, 8, 19 and der (22) more frequently observed. There was no difference occurred between patients with or without p16 gene deletion in complete remission (CR) rate following induction chemotherapy combined with tyrosine kinase inhibitors (TKIs) . However, after three cycles of chemotherapy, the MMR and CMR rate in the p16 gene deletion group was lower than patients with wild-type p16 gene (P=0.034, P=0.036) . The p16 gene deletion patients showed no significant differences in MMR, CMR and relapse rate between Imatinib or Dasatinib plus chemotherapy (P>0.05) . Deletion of p16 gene was significantly associated with poor outcomes including worse overall survival (OS) (37.1% vs 54.1%, P=0.037) , lower disease free-survival (DFS) (12.4% vs 45.9%, P=0.026) , and increased cumulative incidence of relapse (P=0.033) . Among the 25 patients with p16 deletion, 14 underwent allo-HSCT and the median survival was 21 months, better than that of patients received chemotherapy alone (12 months) (P=0.030) . Conclusion: This study indicated that deletion of p16 was associated with poor prognosis in adult Ph(+) ALL, and the utility of second-generation TKI (Dasatinib) does not necessarily have an edge on efficacy over Imatinib, but allo-HSCT has the potential of elongating life expectancy. It is an important significance to define the status of p16 in Ph(+) ALL for predicting prognosis and guiding therapy decision-making.

Detection and study of plasma D-dimer change in patients with acute exacerbation of chronic obstructive pulmonary disease.

The purpose of this study was to observe the change in plasma D-dimer of patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). The patients were divided into three groups, i.e., AECOPD group, stable COPD group (COPD kept stable after treatment) and a healthy control group. The content of plasma fibrinogen (FIB) and D-dimer of all research subjects was detected and the difference between groups was analyzed. Moreover, pulmonary functions of patients in the AECOPD group and the stable COPD group, including forced expiratory volume in 1 second (FEV1%) and forced vital capacity rate of 1 second (FEV1/FVC), and blood gas (oxygen partial pressure (PO2) and partial pressure of carbon dioxide (PaCO2), were detected; and the differences between the two groups and the possible correlation were analyzed. Compared to the COPD stable group and the control group, the AECOPD group had a statistically significant higher content of plasma FIB and D-dimer (p less than 0.05); the content of plasma FIB and D-dimer of the COPD stable group was much higher than that of the healthy control group, but the difference had no statistical significance (p > 0.05); the content of D-dimer of AECOPD patients was in a negative correlation with FEV1 and PO2 (p smaller than 0.05) and in a positive correlation with PCO2 (p smaller than 0.05). It can be concluded that D-dimer is correlated to the severity of AECOPD; hence, it can be used as an evaluation index for the severity of AECOPD.

Low-frequency ultrasound induces apoptosis of rat aortic smooth muscle cells (A7r5) via the intrinsic apoptotic pathway.

Ultrasound, a non-invasive therapy method, is a potential tool for medical applications, but its biological effects on vascular smooth muscle cells (VSMCs) have not been characterized. The aim of this study was to explore the effect and possible apoptotic mechanism of VSMCs that were induced by low-frequency ultrasound (LFU). Cell viability and apoptosis of A7r5 cells were evaluated after treating A7r5 cells with a continuous 45-kHz 1.0-W/cm(2) ultrasound (exposure time of 0, 10, 20, 30, and 35 s) by MTT assay and flow cytometry. At the optimum ultrasound exposure condition (30 s), gene chip analysis was performed, and the apoptotic signaling pathway was confirmed by reverse transcription-polymerase chain reaction and Western blot. As measured by flow cytometry, LFU significantly induced A7r5 cell apoptosis. Comparing the ultrasound group with the control group, the protein expression of caspase-9 and caspase-3 was increased by 50 and 57%, respectively; the caspase-3 mRNA level was increased by 37.5%. These findings indicate that an intrinsic pathway plays a major role in apoptosis that is induced by LFU and that LFU can induce A7r5 cell apoptosis via caspase-9- and caspase-3-dependent pathways.

Overexpression of HSP27 in cultured human aortic smooth muscular cells reduces apoptosis induced by low-frequency and low-energy ultrasound by inhibition of an intrinsic pathway.

We investigated in vitro the effect of low-frequency and low-energy ultrasound (LFLEU) on apoptosis of an overexpressed HSP27 human aortic smooth muscle cell (HASMC) line. A frequency of 42.6 kHz was used in all experiments. HASMC were exposed to ultrasound and cell viability was evaluated by MTT reduction. Overexpressed HSP27-HASMC was constructed on a pcDNA3.1 vector. Apoptosis was determined 24 h after treatment by flow cytometry; gene display was evaluated with Affimax chips, and HSP27 mRNA and protein expression levels were measured by RT-PCR and Western blotting. The apoptosis rate (at 30 s) was significantly lower in HASMC transfected with HSP27 (7.14 ± 1.73%), compared with cells transfected with a mock plasmid (17.31 ± 2.72%) or a control group (14.23 ± 2.77%), indicating a protective function for apoptosis induced by LFLEU. Gene display analysis showed that caspase-9 expression in HSP27 cell lines was downregulated and caspase-3 upregulated. However, RT-PCR and Western blotting analysis indicated that both caspase-9 and caspase-3 were inhibited at both the mRNA and protein levels. We suggest that overexpressed HSP27 is capable of protecting the LFLEU from apoptosis and that the pathway for this protection is via downregulated caspase-9 and caspase-3 expression.

Dynamics of capturing process of multiple magnetic nanoparticles in a flow through microfluidic bioseparation system.

A mathematical model based on finite-element technique is developed for predicting the transport and capture of multiple magnetic nanoparticles in a microfluidic system that consists of a microfluidic channel enclosed by a permanent magnet. The trajectories and trapping efficiencies are calculated for multiple magnetic nanoparticles when released in the microsystem. It is demonstrated that not only the size but also the point of release of nanoparticles within the microchannel affects the capturing process. Influence of three important parameters, inlet velocities of fluid containing magnetic nanoparticles, diameter of magnetic nanoparticles and magnetic field strength on the trapping efficiency are investigated and optimised values of inlet velocity and magnetic field strength for completely trapping 50 nm magnetic nanoparticles are predicted. It is further demonstrated that the angular position of magnet around the microchannel is also critical in dictating the resulting bioseparation performance. Furthermore, combination of these analyses using the mathematical model will be very useful in the design and development of novel microfluidic bioseparation microsystems.

Selective replication of E1B55K-deleted adenoviruses depends on enhanced E1A expression in cancer cells.

E1B55K-deleted dl1520 could selectively replicate in cancer cells and has been used in clinical trials as an antitumor agent. The mechanism of virus selective replication in cancer cells, including a possible role of p53, is unclear. Studies with established cancer cell lines have demonstrated that some cancer cells are resistant to dl1520 replication, regardless of the p53 status. Hep3B cells supported the E1b-deleted adenoviruses to replicate, whereas Saos2 cells were resistant to viral replication. We applied p53-null Hep3B and Saos2 cells as models to clarify the replication ability of E1B55K-deleted adenoviruses with different expression levels of E1a. We show that lower E1A expression in Saos2 may be the reason for the poor replication in some cancer cells due to the fact that E1a promoter was less activated in Saos2 than in Hep3B. We also demonstrate that the E1B55K protein can increase E1A expression in Saos2 cells for efficient virus replication. In addition, the upstream regions of the E1a promoter have transcriptional activity in Hep3B cells but not in Saos2 cells. The viral E1B55K protein may activate cancer cellular factor(s) that targets the upstream regions of the E1a gene to increase its expression. This is the first study demonstrating that E1B55K protein affects the E1A production levels that is related to cancer selective replication. Our studies have suggested that increase of E1A expression from E1b-deleted adenoviruses may enhance killing cancer cells that otherwise are resistant to viral replication.

Traumatic thrombophlebitis of the superficial dorsal vein of the penis: an occupational hazard.

Several cases of thrombophlebitis of the superficial dorsal vein of the penis (TSDVP) have been reported in the literature. Etiologies may include any of the following: trauma associated with vigorous sexual intercourse; penile strangulation caused by a multitude of entities; penile injection; infection; neoplasm; or surgery. We report a rare case of traumatic TSDVP in a cab driver following repeated injury to the penis by a coin-filled pouch. We review the etiologies, mechanism, and treatment of traumatic TSDVP, and attempt to identify men who may be at similar occupational risk.

Probing the activation of the replicative origin of broad host-range plasmid R1162 with Tus, the E.coli anti-helicase protein.

The E.coli Tus protein is an anti-helicase involved in the termination of chromosome replication. The binding site for this protein, ter, was cloned into derivatives of the broad host-range plasmid R1162. The ter site caused the orientation-specific termination of plasmid replication fork movement in cell extracts containing Tus. Plasmids were constructed so that two sites for initiation of R1162 replication flanked the iteron-containing domain of the origin. In these plasmids, the site next to the AT-rich region within the iteron-containing domain was more active. In addition, when ter was placed between the more active site and the iterons, initiation of replication from this site was specifically inhibited. The data support a model for entry of the essential, plasmid-encoded helicase at one side of the direct repeats, and for its movement primarily in one direction away from these repeats to activate the initiation sites for DNA replication.

[Synthesis and antimicrobial activity of 7-acylamido-3-1, 2, 3-triazol-1-ylmethyl) cephalosporins].

In order to develop oral cephalosporin exhibiting broad-spectrum activity, a series of cephalosporin derivatives (VIII1-12) bearing 1, 2, 3-triazolymethyl substituents on the C3 position were synthesized. 7-Phenylacetamido-3-methyl-3-cephem-4-carboxylic acid (I) was employed as starting material and converted to VIII by procedures of esterification and oxidation, bromination, azido-substitution, dipolarcycloaddition, deprotection, cleavage, and condensation. Minimum inhibitory concentration (MIC) values in vitro showed that VIII2-4.9-11 had a wide antibacterial spectrum against Gram positive and Gram negative bacteria and possessed high activities. Further biological evaluation and the study of oral absorption for the six compounds will be performed.

Deletion of sites for initiation of DNA synthesis in the origin of broad host-range plasmid R1162.

The origin of replication of the broad host-range plasmid R1162 contains two, oppositely facing initiation sites for DNA synthesis. Either of these sites can be deleted from an R1162 plasmid derivative. However, the resulting plasmids are unstable, maintained at a lower copy-number in the cell, and form dimers and other recombinants that are required for propagation of the plasmid. In vitro, a derivative lacking one initiation site is deficient in synthesis of the strand normally initiated from that site. The properties of the intact origin are restored if it contains two oppositely facing sites; one initiation site may substitute for the other, and each site need not be in its original orientation. Overall, the results suggest that synthesis of each strand of R1162 DNA is initiated at a single site, and that there is no efficient system for initiation of lagging strand synthesis during transit of the replication forks.

[Synthesis of 7-(1,7-disubstituted-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamido) -cephalosporins].

A series of new 7-(1, 7-disubstituted-1, 4-dihydro-4-oxo-1, 8-naphthyridine-3-carboxamido)-cephalosporins has been prepared by acylation of the 7-amino group of 7-ADCA, 7-ACA, 7-ACT and 7-ACD with 1, 7-disubstituted-1, 4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid. Mixed carboxylic-carbonic anhydride method was adopted in the reactions. Isolation and purification were fulfilled with Sephadex LH-20 column chromatography and centrifugal-TLC technique. Twenty four new cephalosporin derivatives were synthesized. Their structures have been confirmed by elemental analysis, IR and 1HNMR. In preliminary In vitro antibacterial sensitivity tests, most of these new derivatives were found to show good sensitivity to Gram-positive bacteria. Bacteriostasis were also observed for some Gram-negative bacteria.

[Synthesis of 7 beta-(6-substituted-2-quinolone-3-acetamido)cephalosporins].

A series of new 7 beta-(6-substituted-2-quinolone-3-acetamido)cephalosporins has been prepared by acylation of the 7 beta-amino group of 7-ADCA, 7-ACA, 7-ACT and 7-ACD with 6-substituted-2-quinolone-3-acetic acids. CDI (N,N'-Carbonyldiimidazole) method was mainly adopted and active ester method was also employed in the reactions. Isolation and purification were fulfilled with the combined methods of Sephadex LH-20 column chromatography and centrifugal TLC technique. Sixteen new cephalosporin derivatives were synthesized. Their structures have been confirmed by elemental analysis, IR and 1HNMR. The preliminary in vitro antibacterial tests showed that these new compounds exhibited high activity to gram-positive and some negative bacteria. Bacteriostasis of most of the compounds was equal to cefazolin and sodium penicillin G. Compound III3, III4, III8, III10 and III11 possessed higher activity on the resistant Staphylococcus aureus S22 and Proteus vulgaris OX19 than cefazolin and sodium penicillin G. Further biological evaluation for these compounds is expected to be carried out.