A Mettl16/m6A/mybl2b/Igf2bp1 axis ensures cell cycle progression of embryonic hematopoietic stem and progenitor cells

Prenatal lethality associated with mouse knockout of Mettl16, a recently identified RNA N6-methyladenosine (m6A) methyltransferase, has hampered characterization of the essential role of METTL16-mediated RNA m6A modification in early embryonic development. Here, using cross-species single-cell RNA sequencing analysis, we found that during early embryonic development, METTL16 is more highly expressed in vertebrate hematopoietic stem and progenitor cells (HSPCs) than other methyltransferases. In Mettl16-deficient zebrafish, proliferation capacity of embryonic HSPCs is compromised due to G1/S cell cycle arrest, an effect whose rescue requires Mettl16 with intact methyltransferase activity. We further identify the cell-cycle transcription factor mybl2b as a directly regulated by Mettl16-mediated m6A modification. Mettl16 deficiency resulted in the destabilization of mybl2b mRNA, likely due to lost binding by the m6A reader Igf2bp1 in vivo. Moreover, we found that the METTL16-m6A-MYBL2-IGF2BP1 axis controlling G1/S progression is conserved in humans. Collectively, our findings elucidate the critical function of METTL16-mediated m6A modification in HSPC cell cycle progression during early embryonic development.

Efficacy and safety of intrathecal pemetrexed for TKI-failed leptomeningeal metastases from EGFR+ NSCLC: an expanded, single-arm, phase II clinical trial

BACKGROUND

This study aimed to evaluate the efficacy and safety of intrathecal pemetrexed (IP) for treating patients with leptomeningeal metastases (LM) from non-small-cell lung cancer (NSCLC) who progressed from epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) treatment in an expanded, prospective, single-arm, phase II clinical study (ChiCTR1800016615).

PATIENTS AND METHODS

Patients with confirmed NSCLC-LM who progressed from TKI received IP (50 mg, day 1/day 5 for 1 week, then every 3 weeks for four cycles, and then once monthly) until disease progression or intolerance. Objectives were to assess overall survival (OS), response rate, and safety. Measurable lesions were assessed by investigator according to RECIST version 1.1. LM were assessed according to the Response Assessment in Neuro-Oncology (RANO) criteria.

RESULTS

The study included 132 patients; 68% were female and median age was 52 years (31-74 years). The median OS was 12 months (95% confidence interval 10.4-13.6 months), RANO-assessed response rate was 80.3% (106/132), and the most common adverse event was myelosuppression (n = 42; 31.8%), which reversed after symptomatic treatment. The results of subgroup analysis showed that absence of brain parenchymal metastasis, good Eastern Cooperative Oncology Group score, good response to IP treatment, negative cytology after treatment, and patients without neck/back pain/difficult defecation had longer survival. Gender, age, previous intrathecal methotrexate/cytarabine, and whole-brain radiotherapy had no significant influence on OS.

CONCLUSIONS

This study further showed that IP is an effective and safe treatment method for the EGFR-TKI-failed NSCLC-LM, and should be recommended for these patients in clinical practice and guidelines.

In-Vivo Induced CAR-T Cell for the Potential Breakthrough to Overcome the Barriers of Current CAR-T Cell Therapy

Chimeric antigen receptor T cell (CAR-T cell) therapy has shown impressive success in the treatment of hematological malignancies, but the systemic toxicity and complex manufacturing process of current autologous CAR-T cell therapy hinder its broader applications. Universal CAR-T cells have been developed to simplify the production process through isolation and editing of allogeneic T cells from healthy persons, but the allogeneic CAR-T cells have recently encountered safety concerns, and clinical trials have been halted by the FDA. Thus, there is an urgent need to seek new ways to overcome the barriers of current CAR-T cell therapy. In-vivo CAR-T cells induced by nanocarriers loaded with CAR-genes and gene-editing tools have shown efficiency for regressing leukemia and reducing systemic toxicity in a mouse model. The in-situ programming of autologous T-cells avoids the safety concerns of allogeneic T cells, and the manufacture of nanocarriers can be easily standardized. Therefore, the in-vivo induced CAR-T cells can potentially overcome the abovementioned limitations of current CAR-T cell therapy. Here, we provide a review on CAR structures, gene-editing tools, and gene delivery techniques applied in immunotherapy to help design and develop new in-vivo induced CAR-T cells.

Long lifetime of bialkali photocathodes operating in high gradient superconducting radio frequency gun

High brightness, high charge electron beams are critical for a number of advanced accelerator applications. The initial emittance of the electron beam, which is determined by the mean transverse energy (MTE) and laser spot size, is one of the most important parameters determining the beam quality. The bialkali photocathodes illuminated by a visible laser have the advantages of high quantum efficiency (QE) and low MTE. Furthermore, Superconducting Radio Frequency (SRF) guns can operate in the continuous wave (CW) mode at high accelerating gradients, e.g. with significant reduction of the laser spot size at the photocathode. Combining the bialkali photocathode with the SRF gun enables generation of high charge, high brightness, and possibly high average current electron beams. However, integrating the high QE semiconductor photocathode into the SRF guns has been challenging. In this article, we report on the development of bialkali photocathodes for successful operation in the SRF gun with months-long lifetime while delivering CW beams with nano-coulomb charge per bunch. This achievement opens a new era for high charge, high brightness CW electron beams.

CSF-1R inhibition disrupts the dialog between leukaemia cells and macrophages and delays leukaemia progression

Research in the last few years has revealed that leukaemic cells can remodel the bone marrow niche into a permissive environment favouring leukaemic stem cell expansion. Tumour-associated macrophages (TAMs) are prominent components of the tumour microenvironment and play an important role in the onset and progression of solid tumours. However, little is known about their role in the development of acute lymphoblastic leukaemia (ALL). Using a unique mouse model of T-ALL induced by injection of EL4 T-cell lymphoma cells to syngeneic C57BL/6 mice, we report herein that ALL leads to the invasion of leukaemia-associated monocyte-derived cells (LAMs) into the bone marrow and spleen of T-ALL mice. Furthermore, we found that leukaemia cells could polarize bone marrow-derived macrophages (BMDMs) into LAMs. In turn, LAMs were able to protect leukaemia cells from drug-induced apoptosis in vitro. Therapies targeted against the TAMs by inhibiting colony stimulating factor-1 receptor (CSF-1R) have emerged as a promising approach for cancer treatment. In this study, we demonstrate that CSF-1R inhibition inhibits the viability of BMDMs, blocks LAMs polarization and reduces the abundance of LAMs in T-ALL mice. In vivo, combination treatment of CSF-1R inhibitor and vincristine (VCR) dramatically increased the survival of T-ALL mice and delayed leukaemia progression compared with VCR monotherapy. Finally, these data reinforce the role of microenvironments in leukaemia and suggest that macrophages are a potential target for the development of novel therapeutic strategies in T-ALL.

High-Brightness Continuous-Wave Electron Beams from Superconducting Radio-Frequency Photoemission Gun

Continuous-wave photoinjectors operating at high accelerating gradients promise to revolutionize many areas of science and applications. They can establish the basis for a new generation of monochromatic x-ray free electron lasers, high-brightness hadron beams, or a new generation of microchip production. In this Letter we report on the record-performing superconducting rf electron gun with CsK_{2}Sb photocathode. The gun is generating high charge electron bunches (up to 10  nC/bunch) and low transverse emittances, while operating for months with a single photocathode. This achievement opens a new era in generating high-power beams with a very high average brightness.

Experimental Demonstration of Hadron Beam Cooling Using Radio-Frequency Accelerated Electron Bunches

Cooling of beams of gold ions using electron bunches accelerated with radio-frequency systems was recently experimentally demonstrated in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Such an approach is new and opens the possibility of using this technique at higher energies than possible with electrostatic acceleration of electron beams. The challenges of this approach include generation of electron beams suitable for cooling, delivery of electron bunches of the required quality to the cooling sections without degradation of beam angular divergence and energy spread, achieving the required small angles between electron and ion trajectories in the cooling sections, precise velocity matching between the two beams, high-current operation of the electron accelerator, as well as several physics effects related to bunched-beam cooling. Here we report on the first demonstration of cooling hadron beams using this new approach.

Isolation and sequence analysis of the complete VP2 gene of canine parvovirus from Chinese domestic pets and determination of the pathogenesis of these circulating strains in beagles

Canine parvovirus (CPV) causes acute gastroenteritis in domestic dogs, cats, and several wild carnivore species. In this study, the full-length VP2 gene of 36 CPV isolates from dogs and cats infected between 2016 and 2017 in Beijing was sequenced and analyzed. The results showed that, in dogs, the new CPV-2a strain was the predominant variant (n = 18; 50%), followed by the new CPV-2b (n = 6; 16.7%) and CPV-2c (n = 3; 8.3%) strains, whereas, among cats, the predominant strain was still CPV-2 (n = 9; 25%). One new CPV-2a strain, 20170320-BJ-11, and two CPV-2c strains, 20160810-BJ-81 and 20170322-BJ-26, were isolated and used to perform experimental infections. Multiple organs of beagles that died tested PCR positive for CPV, and characteristic histopathological lesions were observed in organs, including the liver, spleen, lungs, kidneys, small intestines, and lymph nodes. Experimental infections showed that the isolates from the epidemic caused high morbidity in beagles, indicating their virulence in animals and suggesting the need to further monitor evolution of CPV in China.

pUC18-CpG stimulates RAW 264.7 via TBK1-mediated pathway and presents adjuvanticity in mice

Phosphorothioate CpG oligodeoxynucleotides (ODN) are reported to be recognized by the membrane-bound TLR9 and trigger the MyD88-dependent up-regulation of Type I interferons and pro-inflammatory cytokines. Whether plasmids containing multiple CpG motifs stimulate the same signaling pathway is yet to be determined. The present results show that the CpG motifs enrich plasmid pUC18-CpG stimulates RAW 264.7 in vitro, mainly through the TBK1-mediated signaling pathway, causing the up-regulation of IFN-β, and pro-inflammatory cytokines TNF-α and IL-6. When pUC18-CpG is co-administered with the recombinant Echinococcus granulosus antigen, the antigen-specific antibody titers are markedly increased compared to the Quil-A adju- vanted group. Antigen specific cytokine quantification shows that cytokine profiles from the pUC18-CpG adjuvanted-group are switched to a Th1-biased immune response.

Genotyping and pathogenic characterization of canine distemper virus based on mutations in the hemagglutinin gene in Chinese domestic dogs

Canine distemper virus (CDV) infects wild and domestic Canidae worldwide. The hemag- glutinin (H) gene has the highest genetic variation in the genome of this virus. Thus, the H gene is commonly used for lineage identification and genetic analyses. In order to study the genetic characteristics and pathogenicity of CDV strains prevalent in China, 132 samples were collected from domestic dogs with suspected CDV infection, 58 samples were confirmed to be positive, and the H gene was successfully amplified from 15 samples. The epidemic strain was identified as type Asia-1 and the novel mutations, A51T, V58I, R179K and D262N, were detected in this strain. Isolated strains, BJ16B53, BJ16B14, and BJ17B8, were used for an animal infection experiment in raccoon dogs. BJ16B53 and BJ16B14 were found to cause clinical symptoms, death, and exten- sive lesions in various organs. These results are expected to facilitate the development of effective strategies to monitor and control CDV infection in China.

Phospholipase C signaling is involved in porcine reproductive and respiratory syndrome virus infection in cell cultures

The phospholipase C (PLC) is a family of kinases that hydrolyze phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] to generate two second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), which stimulate distinct downstream signaling. Recently, it has been reported that PLC signaling is activated by multiple viruses for efficient replication and the virus-induced inflammatory response. In this study, we demonstrated that PLC-specific inhibitor U73122 strongly suppressed porcine reproductive and respiratory syndrome virus (PRRSV) productive infection in cell cultures. The inhibitor affected both viral post-binding cell entry and post-entry processes. The virus infection led to an early transient activation of PLCγ-1 at 0.5 h post-infection (hpi), and sustained event at a stage from 4 to 16 hpi in MARC-145 cells. In addition, U73122 inhibited the activation of p38 MAPK signaling stimulated by PRRSV infection, suggesting that PLC signaling may be associated with the virus infection-induced inflammatory response. Taken together, these studies suggested that PLC signaling played an important role in PRRSV infection or pathogenesis. Keywords: PRRSV; U73122; phospholipase C; PLCγ-1.

Design of a high-bunch-charge 112-MHz superconducting RF photoemission electron source

High-bunch-charge photoemission electron-sources operating in a continuous wave (CW) mode are required for many advanced applications of particle accelerators, such as electron coolers for hadron beams, electron-ion colliders, and free-electron lasers. Superconducting RF (SRF) has several advantages over other electron-gun technologies in CW mode as it offers higher acceleration rate and potentially can generate higher bunch charges and average beam currents. A 112 MHz SRF electron photoinjector (gun) was developed at Brookhaven National Laboratory to produce high-brightness and high-bunch-charge bunches for the coherent electron cooling proof-of-principle experiment. The gun utilizes a quarter-wave resonator geometry for assuring beam dynamics and uses high quantum efficiency multi-alkali photocathodes for generating electrons.

First Measurement of Electron Neutrino Appearance in NOvA

We report results from the first search for ν_{μ}→ν_{e} transitions by the NOvA experiment. In an exposure equivalent to 2.74×10^{20} protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99±0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07±0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π<δ_{CP}<0.5π in the inverted mass hierarchy at the 90% C.L.

Correlation research on the protein expression (p75NTR, bax, bcl-2, and caspase-3) and cortical neuron apoptosis following mechanical injury in rat

OBJECTIVE

In this study, we aimed to survey the role of p75NTR, bax, bcl-2, and caspase-3 in the progress of traumatic brain injury (TBI).

MATERIALS AND METHODS

A mechanical trauma model of vital neurons was established by putting external pressure, contusion and centrifugal acceleration on neurons. Morphological change, survival rate, assay of LDH activity, and apoptosis rate were evaluated for mild, medium and severe injury models. The expression of bax, bcl-2, caspase-3, p75NTR, p75NTR mRNA was determined by immunohistochemistry, immunofluorescence, Western blotting and RT-PCR.

RESULTS

There was a transient high level Bcl-2 protein within 2 h after injury to increase neuronal tolerance and avoid apoptosis. Subsequently p75NTR, Bax/Bcl-2, and Caspase-3 reached their peaks from 48 to 72 h accompanied with the maximum apoptosis rate.

CONCLUSIONS

Our results suggest that apoptosis ratio in varying degree injury groups are correlated with the expression level of p75NTRmRNA, p75NTR, Caspase-3, Bax/Bcl-2 ratio.

The ADAMTS1 Gene Is Associated with Familial Mandibular Prognathism

Mandibular prognathism is a facial skeletal malocclusion. Until now, the genetic mechanism has been unclear. The goal of this study was to identify candidate genes or genomic regions directly associated with mandibular prognathism development, by employing whole genome sequencing. A large Chinese family was recruited, composed of 9 affected and 12 unaffected individuals, and the inheritance pattern of this family tends to be autosomal dominant. A single-nucleotide missense mutation in the ADAMTS1 gene (c. 742I>T) was found to segregate in the family, given that the affected individuals must be heterozygous for the mutation. For mutation validation, we screened this candidate mutation and 15 tag single-nucleotide polymorphisms in the coding sequence of ADAMTS1 among 230 unrelated cases and 196 unrelated controls using Sequenom Massarray and found that 3 in 230 cases carried this mutation and none of the controls did. Final results suggested that 2 single-nucleotide polymorphisms (rs2738, rs229038) of ADAMTS1 were significantly associated with mandibular prognathism.

Increased signal transducer and activator of transcription 3 (STAT3) and decreased cyclin D1 in recurrent astrocytic tumours compared with paired primary astrocytic tumours

This study compared the levels of signal transducer and activator of transcription 3 (STAT3) and cyclin D1 protein in paired primary and recurrent astrocytic tumours, and analysed their correlation with clinicopathological and treatment factors. A total of 48 samples from 24 patients who had undergone surgical removal of primary and recurrent astrocytic tumours were analysed. Levels of STAT3 and cyclin D1 protein were detected using immunohistochemistry. Increased STAT3 and decreased cyclin D1 levels were observed in recurrent astrocytic tumours compared with their paired primary tumours. There was a significant correlation between higher levels of STAT3 protein and shorter progression-free survival in primary tumours after surgery (r = 0.417), and a significant correlation between decreased cyclin D1 protein levels and radiotherapy in recurrent tumours (r = 0.468). It was concluded that increased STAT3 and decreased cyclin D1 protein levels may contribute to the recurrence of astrocytic tumours. Detection of STAT3 may be useful in predicting progressionfree survival in primary astrocytic tumours after surgery. In addition, radiotherapy may decrease cyclin D1 levels in astrocytic tumours, but the nature of this association requires further investigation.

Bmi-1 siRNA inhibited ovarian cancer cell line growth and decreased telomerase activity

The knockdown of Bmi-1 could effectively suppress cancer cell proliferation and tumourigenicity in several cancers. This study aims to investigate whether or not Bmi-1 plays a causative role in the proliferation of ovarian epithelial cancer cells and telomerase activity. The messenger RNA (mRNA) and protein expression levels of Bmi-1 in the human ovarian carcinoma cell line OVCAR-3 were downregulated by Bmi-1 siRNA, as confirmed by real-time polymerase chain reaction (PCR) and Western blot. Cell viability was analysed by MTT assay, and telomerase activity was analysed by a modified telomeric repeat amplification protocol. Targeting Bmi-1 with siRNA inhibited Bmi-1 mRNA over five-fold compared with the control cells, and inhibited Bmi-1 protein expression over three-fold compared with control cells. The viability of the OVCAR-3 ovarian cancer cell line was reduced by Bmi-1 mRNA compared to control cells. Telomerase activity was decreased 22.73% (from 0.33 to 0.255) by Bmi-1 siRNA treatment compared to control cells. As Bmi-1 siRNA depressed telomerase activity, cell immortalisation may be prevented; thus, silencing Bmi-1 may be a potential therapy to manage ovarian cancer.

Correlation of Bmi-1 expression and telomerase activity in human ovarian cancer

This study investigates the correlation between the oncoprotein Bmi-1 and telomerase activity in ovarian cancer. A real-time polymerase chain reaction (PCR) method is used to detect the messenger RNA (mRNA) expression of Bmi-1 protein in 47 ovarian epithelial cancer cases, and immunohistochemistry is used to detect Bmi-1 protein expression in the tissues. A modified telomeric repeat amplification protocol (TRAP) is used to detect telomerase activity. Western blotting is used to detect the expression of telomerase hTERT in the tissues studied. Compared to normal ovarian epithelial tissue, Bmi-1 protein in the 47 ovarian epithelial cancer cases showed higher expression and was related to pathological grade and clinical stage. Significantly higher Bmi-1 levels were found among different clinocopathological types of the cancer (P<0.05). Grade G3 cases expressed Bmi-1 at a higher rate (93.10%) than did grade G2 cases (61.11%). Expression in phase II and phase III cases was lower (66.67%) than in phase IV (92.31%). In ovarian epithelial cancer tissues, 87.23% (41/47) cases demonstrated positive telomerase activity, whereas no activity was observed in normal tissues. The majority (90.24%) of specimens with positive telomerase activity showed high Bmi-1 expression levels. Spearman correlation analysis indicated that expression of Bmi-1 protein correlated positively with elevated telomerase activity. Bmi-1 protein is highly expressed in ovarian epithelial cancer tissues, and expression correlates with histological grade and clinical phase. Elevated Bmi-1 expression correlates closely with increased telomerase activity and plays a significant role in the pathogenesis of ovarian cancer.

Short-interfering RNA-mediated silencing of proliferating cell nuclear antigen inhibit proliferation and induce apoptosis in HeLa cells

Proliferating cell nuclear antigen (PCNA) is an important protein for DNA polymerase delta in the nucleus, and shown to have a fundamental role in cellular proliferation. It is overexpressed to support cell growth in cervical carcinoma. To study its role in stress response, we design and use short hairpin RNA (shRNA) to inhibit PCNA expression in HeLa cells and validate its effect on cell proliferation. In this study, three PCNA-shRNA expression vectors are constructed and introduced into HeLa cells, and the cell cycle is analyzed by flow cytometry. Apoptotic cell is detected by single cell gel electrophoresis assay (comet assay), and caspase cleavage is studied also. Expression of PCNA is assessed by real-time reverse transcription-polymerase chain reaction and Western blot analysis. Upon transient transfection with plasmid encoding shRNA, it is found that expression of PCNA decreased in shRNA-transfected cells, downregulation of PCNA inhibit cell growth and induce apoptosis in HeLa cells. PCNA downregulation also increase cell population in the G0-G1 phase. In conclusion, our findings demonstrate that shRNA can inhibit the DNA replication and induce apoptosis in HeLa cells effectively and, therefore, could be used as a new potential anticancer tool for therapy of human cervical carcinoma.

Cell-free assays for gamma-secretase activity

The amyloid b-protein (Ab) deposited in Alzheimer's disease (AD) is a normally secreted proteolytic product of the amyloid b-protein precursor (APP). Generation of Ab from the APP requires two sequential proteolytic events: an initial b-secretase cleavage at the amino terminus of the Ab sequence followed by g-secretase cleavage at the carboxyl terminus of Ab. We describe the development of a robust in vitro assay for g-secretase cleavage by showing de novo Ab production in vitro and establish that this assay monitors authentic gamma-secretase activity by documenting the production of a cognate g-CTF, confirming the size of the Ab produced by mass spectrometry, and inhibiting cleavage in this system with multiple inhibitors that alter g-secretase activity in living cells. Using this assay, we demonstrate that the g-secretase activity 1) is tightly associated with the membrane, 2) can be solubilized, 3) has a pH optimum of 6.8 but is active from pH 6.0 to pH >8.4, and 4) ascertain that activities of the g-40 and g-42 are indeed pharmacologically distinct. These studies should facilitate the purification of the protease or proteases that are responsible for this unusual activity, which is a major therapeutic target for the treatment of AD.

5-Alkyltryptamine derivatives as highly selective and potent 5-HT1D receptor agonists

A series of 5-alkyltryptamines (6) and the corresponding conformationally constrained analogues (8) have been synthesized. The structure activity relationships (SAR) at the 5-position of the indole skeleton and the ethylamine side chain have been studied. Functional activities were assessed using isolated rabbit saphenous vein. Potent, selective ligands were found (6e, Ki 2.5 nM, 5-HT1B/5-HT1D 125-fold) that have potential for treating acute migraine.

6-Bicyclopiperazinyl-1-arylsulfonylindoles and 6-bicyclopiperidinyl-1-arylsulfonylindoles derivatives as novel, potent, and selective 5-HT6 receptor antagonists

A novel series of 6-bicyclopiperazinyl-1-arylsulfonylindoles and 6-bicyclopiperidinyl-1-arylsulfonylindoles derivatives was synthesized and found to be potent and selective 5-HT6 receptor antagonists.

Synthesis and antibacterial evaluation of [1,3]benzothiazino[3,2-a]quinoline- and [3,1]benzothiazino[1,2-a]quinoline-6-carboxylic acid derivatives

A series of [1,3]benzothiazino[3,2-a]quinoline- (5) and [3,1]benzothiazino[1,2-a]quinoline-6-carboxylic acids (10) were synthesized and evaluated for their in vitro antibacterial activity. The activity is discussed in terms of their structural features revealed by molecular orbital correlation.

Potent 6-desfluoro-8-methylquinolones as new lead compounds in antibacterial chemotherapy

In a furtherance of our SAR study on the C-6 position of quinolone antibacterials, a series of 6-desfluoro-8-methylquinolones were synthesized and evaluated for their in vitro antimicrobial activity. As a result of this study, compounds with strong activity against Gram-positive bacteria, including ciprofloxacin-resistant and methicillin-resistant Staphylococcus aureus, were identified. The best Gram-positive antibacterial activity was exhibited by piperidinyl derivative 6c, which was 17 times more potent than ciprofloxacin and displayed extremely high activity against Streptococcus pneumoniae with an MIC value of <0.016 microg/mL. Thus, we have shown that substituent combinations in the quinolone ring, excluding the C-6 fluorine atom, might produce powerful antibacterial agents.

Studies on 6-aminoquinolones: synthesis and antibacterial evaluation of 6-amino-8-methylquinolones

The 6-aminoquinolone had previously been identified as a new class of quinolone antibacterial agents. To continue our structure-activity relationship (SAR) study in this series, novel 6-amino-8-methylquinolone derivatives have now been synthesized and evaluated for in vitro antibacterial activity. We have shown that the coupled presence of a methyl group at the C-8 position with an amino group at C-6 is effective for enhancing antibacterial activity, particularly against Gram-positive bacteria. The SARs associated with the N-1, C-6, and C-7 are discussed. The 1,2,3,4-tetrahydroisoquinolinyl derivative 19v showed the highest antibacterial activity with MIC values on Gram-positive bacteria superior to that of ciprofloxacin, especially against Staphylococcus aureus strains, including those strains which are methicillin-and ciprofloxacin-resistant.

Determination of ion magnetron radial distribution in Fourier transform ion cyclotron resonance mass spectrometry

The spatial distribution of the ion cyclotron orbit 'guiding centers' (magnetron radii) in a Penning trap determines virtually all aspects of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry performance. Here, we demonstrate experimentally a simple method for determining that distribution, based on measuring FTICR mass spectral peak height following dipolar excitation/dipolar detection at various stages of magnetron radial expansion. No instrumental modifications are needed. Such data will make it possible to evaluate theoretical models of space charge and to quantitate and optimize ion formation, ion injection, ion trapping, ion transfer, photodissociation and ultrahigh-resolution FTICR experiments.