Advances in the delivery of antisense oligonucleotides for combating bacterial infectious diseases.

Discovery and development of new antibacterial drugs against multidrug resistant bacterial strains have become more and more urgent. Antisense oligonucleotides (ASOs) show immense potential to control the spread of resistant microbes due to its high specificity of action, little risk to human gene expression, and easy design and synthesis to target any possible gene. However, efficient delivery of ASOs to their action sites with enough concentration remains a major obstacle, which greatly hampers their clinical application. In this study, we reviewed current progress on delivery strategies of ASOs into bacteria, focused on various non-virus gene vectors, including cell penetrating peptides, lipid nanoparticles, bolaamphiphile-based nanoparticles, DNA nanostructures and Vitamin B12. The current review provided comprehensive understanding and novel perspective for the future application of ASOs in combating bacterial infections.

A potent and selective antimicrobial poly(amidoamine) dendrimer conjugate with LED209 targeting QseC receptor to inhibit the virulence genes of gram negative bacteria.

The pandemic of multidrug-resistant Gram negative bacteria (GNB) is a worldwide healthcare concern, and very few antibiotics are being explored to match the clinical challenge. Recently, amino-terminated poly(amidoamine) (PAMAM) dendrimers have shown potential to function as broad antimicrobial agents. However, PAMAM displays a generation dependent cytotoxicity to mammalian cells and low selectivity on bacterial cells, which limits PAMAM to be developed as an antibacterial agent for systemic administration. We conjugated G3 PAMAM with LED209, a specific inhibitor of quorum sensor QseC of GNB, to generate a multifunctional agent PAMAM-LED209. Intriguingly, PAMAM-LED209 showed higher selectivity on GNB and lower cytotoxicity to mammalian cells, yet remained strong antibacterial activity. PAMAM-LED209 also inhibited virulence gene expression of GNB, and did not induce antibiotic-resistance. The present work firstly demonstrated that PAMAM-LED209 conjugate had a highly selective anti-GNB activity and low cytotoxicity, which offered a feasible strategy for combating multidrug-resistant GNB infections. FROM THE CLINICAL EDITOR: This research team demonstrated that a novel PAMAM-LED209 conjugate had highly selective activity against Gram-negative bacteria, coupled with low cytotoxicity, offering a potential strategy for combating multidrug-resistant infections.

A novel pregnane-type alkaloid from Pachysandra terminalis inhibits methicillin-resistant Staphylococcus aureus in vitro and in vivo.

A new kind of pregnane-type alkaloid, 20α-dimethylamino-3ß-senecioylamino-16ß-hydroxy-pregn-5-ene (K-6), was isolated from Pachysandra terminalis Sieb. et Zucc., and its antibacterial activity against MRSA and MRSE was evaluated. We found that K-6 showed antibacterial effects against MRSA and MRSE with minimum inhibitory concentration values (25 mg/L), but did not induce antibiotic resistance in bacteria easily. The administration of K-6 dose-dependently improved the animal survival rate of mice infected with MRSA, with survival rates of 36.34% and 66.67% in the low-dose and high-dose groups, respectively. The protective effects were associated with the reduction of the bacterial titers in the blood and with the morphological amelioration of infected tissues. Scanning and transmission electron microscopy analyses indicated that the cytoplasm shrink of bacterial cells led to noticeable gaps between the cell membrane and cell cytoplasm, and the severely damaged cell membrane resulted in leakage of intracellular content, which ultimately caused the lethal effect of K-6 on bacteria. These findings demonstrated that K-6 is a potential agent against MRSA and MRSE.

Synthesis of Biscoumarin and Dihydropyran Derivatives and Evaluation of Their Antibacterial Activity.

In an attempt to find a new class antibacterial agents, a series of biscoumarins (1-4) and dihydropyrans (5-13) were successfully prepared. The molecular structures of four representative compounds, that is, 4, 5, 8 and 12 were confirmed by single crystal X-ray diffraction study. These synthesized compounds were screened for their antibacterial activity in vitro against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), USA 300 (Los Angeles County clone, LAC), Staphylococcus epidermidis (S. epidermidis ATCC 14990), methicillin-resistant S. epidermidis (MRSE XJ 75284) and Escherichia coli (E. coli ATCC 25922). Additionally, there are two classical intramolecular O-H···O hydrogen bonds (HBs) in biscoumarins 1-4 and the corresponding HB energies were further performed with the density functional theory (DFT) [B3LYP/6-31G*] method.

Synthesis, antibacterial activities, and theoretical studies of dicoumarols.

Four dicoumarols (DC, 2-PyDC, 3-PyDC and 4-PyDC) were synthesized and characterized via IR, (1)H NMR, HRMS, and single crystal X-ray crystallography. Two classical intramolecular O-H···O hydrogen bonds (HBs) stabilized their structures. The total HB energies in DC, 2-PyDC, 3-PyDC and 4-PyDC were calculated with the density functional theory (DFT) [B3LYP/6-31G*] method. The in vitro antibacterial activity of DC, 2-PyDC, 3-PyDC and 4-PyDC against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC) was evaluated by observing the minimum inhibitory concentration and time-kill curves. The results showed that among all the compounds, 2-PyDC exhibited the most potent antibacterial activity.

New biscoumarin derivatives: synthesis, crystal structure, theoretical study and antibacterial activity against Staphylococcus aureus.

Five novel biscoumarins 1-5 were synthesized and characterized. In these compounds, two classical asymmetrical intramolecular O-H···O hydrogen bonds were used to stabilize the whole structures and the HB energies were performed with the density functional theory (DFT) [B3LYP/6-31G*] method. The five compounds were evaluated for their in vitro antibacterial activities against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC) by the means of minimum inhibitory concentration and time-kill curves.

[Auditory event-related potentials in children with functional articulation disorders].

OBJECTIVE: To investigate the central auditory processing function in children with functional articulation disorders (FAD), and possible causes of FAD. METHODS: Twenty-seven children with FAD were selected as the case group and 50 age-matched normal children were selected as the control group. The two groups were compared with respect to the following factors: percentage of individuals with a positive history of language development disorder, and the form, peak latency and peak amplitude of mismatch negativity (MMN) on auditory event-related potentials. RESULTS: Compared with the control group, the case group had a significantly higher percentage of individuals with a positive history of language development disorder (70% vs 8%; P<0.01), a significantly prolonged peak latency of MMN (209 ± 31 ms vs 175 ± 32 ms; P<0.01), and an insignificantly lower peak amplitude of MMN (P>0.05). CONCLUSIONS: Prolonged central auditory processing may be one of the causes of FAD in children.

Promoting effects of chemical permeation enhancers on insulin permeation across TR146 cell model of buccal epithelium in vitro.

To find potential enhancers for facilitating the buccal delivery of insulin, a TR146 cell-culture model of buccal epithelium, cultured on commercially available insert plates, was used to evaluate the permeability-enhancing effects of several traditional and new types of chemical enhancers, including N-acetyl-L-cysteine (NAC), sodium deoxycholate (SDC), sodium nitroprusside (SNP), reduced glutathione (GSH), glutamine (Gln), chitosan (CS), L-arginine (Arg), 1-dodecylazacycloheptan-2-one (Azone), and soybean lecithin (SPC) (50 and 10 µg/mL respectively). Permeability studies were performed to determine the enhancing effects of these compounds on insulin permeation across the cell-culture model. The enhancing effects of the enhancers were assessed by calculating the apparent permeability coefficients and enhancement ratio. Cytotoxicity of the permeation enhancers at different concentrations was investigated by using the methylthiazolydiphenyl-tetrazolium bromide (MTT) assay. Results showed that 50 µg/mL of NAC, SDC, GSH, CS, Arg, Azone, SPC, SNP, and 10 µg/mL of SNP had a significant enhancing effect on promoting the transport of insulin across the TR146 cell model. MTT assays showed that 50 µg/mL of Gln, Azone, SDC, SNP, Arg, 10 µg/mL SDC, and Arg had obvious toxic effects on TR146 cells. Therefore, NAC, GSH, CS, SPC, and SNP appear to be safe, effective permeability enhancers that promote the transport of insulin across the TR146 cell-culture model of buccal epithelium and may be potential enhancers for buccal delivery of insulin with both low toxicity and high efficiency.

A modified single-prolonged stress model for post-traumatic stress disorder.

In the rat, single-prolonged stress (SPS) model produces a core symptom of post-traumatic stress disorder (PTSD), the enhanced fear response to the traumatic cue (conditioned fear response). This investigative tool is typically used for PTSD studies. However, whether SPS can produce another core symptom of PTSD, hyperarousal (the sensitized fear response in animal models), has not been evaluated. It is also not clear whether SPS can enhance both conditioned and sensitized fear responses after different incubation times. In this study, a single inescapable electric foot shock was given to rats immediately after SPS procedures (SPS&S). After different incubation times (1, 7 or 14 days), the conditioned or sensitized fear response was measured by re-exposing the stressed rats to the shock context or a neutral tone in a novel environment. Additionally, paroxetine, a selective serotonin reuptake inhibitor (SSRI) was administered after SPS&S for 14 days to test its potential preventive effect on PTSD-like symptoms. We observed that conditioned fear persisted and sensitized fear increased with ongoing incubation times after SPS&S. Early rapid intervention with paroxetine after SPS&S ameliorated PTSD-like symptoms in both fear responses and anxiety behaviors. Our data suggests that this modified SPS&S model may be both novel and predictably mimic the clinical characteristics of PTSD better than other investigative paradigms.

The effect of Madopar on the pharmacokinetics of ropinirole in healthy Chinese volunteers.

Ropinirole is a nonergoline dopamine D(2)-receptor agonist and has been proven to be effective in both monotherapy and combination therapy for idiopathic Parkinson's disease. The purpose of the present study was to examine the effect of Madopar on the pharmacokinetics of ropinirole in healthy Chinese volunteers by using liquid chromatography tandem mass spectrometry (HPLC/MS/MS). A single dose of 1mg ropinirole was given orally after administration of the placebo or Madopar (containing 200 mg levodopa and 50 mg benserazide) to six healthy males and six healthy females in a cross-over randomized study with a minimum washout period of 8 days. Pharmacokinetic parameters were calculated for both treatments. Coadministration of ropinirole and Madopar did not result in a notable change in rate or extent of availability of ropinirole, as shown by the ratios (90% confidence intervals) of 1.045 (0.900, 1.222) for C(max) (maximum plasma concentration) and 1.167 (1.086, 1.262) for AUC(0-inf) (the area under the concentration-time curve). Likewise, no significant difference in any of the other pharmacokinetic parameters [T(max) (the time needed to reach the C(max)), MRT (mean residence time), volume of distribution (V/F), and clearance (CL/F)] was observed between the treatment groups. No clinically relevant adverse effects were detected under either conditions and there are no pharmacokinetic grounds for adjusting the dose of ropinirole when given in combination with Madopar in Chinese patients.

[The experimental study of simvastatin on improving aspirin resistance in diabetic rats].

OBJECTIVE: The purpose of the present study was to investigate the effects of the combination of aspirin, simvastatin in diabetic rat on platelet function. METHODS: Eight-week-old male Wistar rats were selected and randomly divided into diabetic group (n=48) and normal control group (n=48). Diabetic rats were injected with 1% STZ (65mg/kg, dissolved in 0.l mmol/L, pH 4.5 citrate buffer) to induce diabetic model and the rats in normal control group were injected with the same dose of citrate buffer. A rat with blood glucose greater than 16.8 mmol/L and along with diabetic symptoms of polydipsia, polyuria and weight loss was considered the successful model of diabetes. Diabetic rats and normal Wistar rats were randomly divided into 4 groups and given aspirin(10 mg/kg), simvastatin(2 mg/kg), combination of aspirin(10mg/kg) and simvastatin(2 mg/kg), PBS for 8 weeks, respectively. The platelet function and the expression of CD62P were evaluated. The levels of nitric oxide (NO), endothelin (ET), thromboxane B2(TXB2), prostacyclin (PGI2), adiponectin (APN), TXB2 were detected in the serum. The expressions of heme oxygenase-1(HO-1), HO-2, endothelial nitric oxide synthase(e-NOS), p-eNOS, B-cell lymphoma-2(Bcl-2), cyclooxygenase-2(COX-2) in thoracic aorta were evaluated by Western blot. RESULTS: Compared with control rats, diabetic rats had high platelet aggregation and activation (P<0.05), which treated aspirin also showed lower aspirin sensitivity (P<0.05). The combination of drugs upregulated the expression of HO-1, eNOS, p-eNOS, BCL-2, APN levels and decreased the expression of COX-2, and had a greater inhibitory effect on platelet aggregation and activation. The combination of drugs improved endothelial function, adjusted TXA2/PGI2 levels and increased NO levels, which resulted in a great potential antiplatelet effect. CONCLUSIONS: These results suggest that simvastatin may improvethe effect of aspirin on anti-platelet function in diabetic rats.

Synthesis of biscoumarin and dihydropyran derivatives as two novel classes of potential anti-bacterial derivatives.

A series of bisoumarin (1-4) and dihydropyran (5-8) derivatives were successfully synthesized as new antibacterial agents. The molecular structures of three representative compounds 1, 5 and 7 were confirmed by single crystal X-ray diffraction study. Among these compounds tested toward Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC), compounds 1 and 2 displayed the most potent antibacterial activity. Additionally, the HB energy in biscoumarins 1-4 was calculated by density functional theory (DFT) [B3LYP/6-31G*] method.

Synthesis and pharmacological evaluations of 4-hydroxycoumarin derivatives as a new class of anti-Staphylococcus aureus agents.

OBJECTIVES: Due to the increasing prevalence of drug-resistant Staphylococcus aureus infection, we develop novel 4-hydroxycoumarin derivatives as antimicrobials. METHODS: The antibacterial activity of 4-hydroxycoumarin derivatives against drug-susceptive S. aureus (ATCC 29213) and methicillin-resistant S. aureus (MRSA) were evaluated using minimal inhibitory concentration (MIC) assay; the activity of favourable compound was further observed using bacterial growth curves assay and in the MRSA infection mice. KEY FINDINGS: Compared with dihydropyran derivatives, compound 1 as one of biscoumarins showed most potent activity with MIC values of 4-8 µg/ml and apparently inhibited the growth rate of S. aureus ATCC 29213 and USA300 strain in concentrations of both 16 and 32 mg/ml. In the mice infected with MRSA USA300, administration of 5 mg/kg compound 1 improved the animal survival rate to 66.7%, and improved the pathological change in lung tissue compared with the infection model animals. No significant cytotoxicity of compound 1 was observed on the umbilical vein endothelial cells (HUVECs) under the concentration of 800 µg/ml. CONCLUSION: Compared with the dihydropyran derivatives, biscoumarins exhibited more promising activity against both drug-sensitive and drug-resistant S. aureus, and it is efficacious in treating MRSA infections in mouse models with a favourable safety in human cells.

Protective effects of cyclosporine and allopurinol on transient global cerebral ischemia in gerbils.

The effects of cyclosporine and allopurinol on neuronal death following global cerebral ischemia were evaluated in Mongolian gerbils. The animals were randomly divided into four groups of 12 each: (1) sham operation as control, (2) occlusion of the bilateral common carotid arteries for 12 min and treatment with physiological saline, (3) occlusion plus treatment with 5 mg/kg of cyclosporine, and (4) occlusion plus treatment with 100 mg/kg of allopurinol 30 min before cerebral ischemia and daily thereafter for 6 days. On the 7th day after ischemia or sham operation, the gerbils' brains were removed. The number of necrotic pyramidal cells in the cortex and hippocampal CA1 was evaluated and tissue chemiluminescence (reflecting the presence of superoxide radicals) and lipid peroxides were examined. The number of necrotic pyramidal cells in each field of view (×100) of the cortex was 115±79 after ischemia, which was significantly larger than 14±8 in the control group, and was 45±33 and 60±49 after treatment with cyclosporine and allopurinol, respectively. The number of surviving pyramidal cells per mm length after ischemia in CA1 was 37±14, which was significantly smaller than 174±30 in the control group, but 78±31 following treatment with was cyclosporine, and 108±53 with allopurinol. A reduced number of necrotic pyramidal cells was associated with lower tissue chemiluminescence and lipid peroxides. The results suggest that both cyclosporine and allopurinol can inhibit neuronal death after global cerebral ischemia, and that autoimmunization and superoxide radicals are partially responsible for neuronal death.

Synthesis, crystal structures, and anti-drug-resistant Staphylococcus aureus activities of novel 4-hydroxycoumarin derivatives.

Four novel 4-hydroxycoumarin derivatives (4-MBH, 3-MBH, 4-MDT and 3-MDT) were successfully synthesized and their structures were verified by single-crystal X-ray crystallography. All target compounds were evaluated for their in vitro antibacterial activity against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC). The minimum inhibitory concentration and time-kill curves were obtained for the test compounds and antibiotics. Among the tested compounds, 3-MBH showed the most potent antibacterial activities.

The effects and outcomes of electrolyte disturbances and asphyxia on newborns hearing.

OBJECTIVE: To determine the effect of electrolyte disturbances (ED) and asphyxia on infant hearing and hearing outcomes. STUDY DESIGN: We conducted newborn hearing screening with transient evoked otoacoustic emission (TEOAE) test on a large scale (>5000 infants). The effects of ED and asphyxia on infant hearing and hearing outcomes were evaluated. RESULT: The pass rate of TEOAE test was significantly reduced in preterm infants with ED (83.1%, multiple logistic regression analysis: P<0.01) but not in full-term infants with ED (93.6%, P=0.41). However, there was no significant reduction in the pass rate in infants with asphyxia (P=0.85). We further found that hypocalcaemia significantly reduced the pass rate of TEOAE test (86.8%, P<0.01). In the follow-up recheck at 3 months of age, the pass rate remained low (44.4%, P<0.01). CONCLUSION: ED is a high-risk factor for preterm infant hearing. Hypocalcaemia can produce more significant impairment with a low recovery rate.

Exocytosis and mobility of histamine vesicles exhibit no difference to that of histamine-negative vesicles in guinea pig superior cervical ganglion neurons.

Our previous studies have shown that histamine existed widely in the sympathetic nervous system and functioned differentially on the sympathetic nerve activation level. Therefore, in this study, we tried to find out whether it is the special exocytosis/recycling of histamine-containing vesicles that contribute to those differential histamine synaptic effects. By using N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino) styryl) pyridinium dibromide and histamine immunostaining methods, we confirmed that histamine was stored in small vesicles and found that the histamine-containing vesicles included the recycling pool and the reserve pool. However, we also found for the first time that the release and mobility kinetics of histamine-containing vesicles were identical to that of histamine-negative vesicles. In conclusion, these findings provide further characters of histamine as a sympathetic neurotransmitter.

Effects of sympathetic histamine on vasomotor responses of blood vessels in rabbit ear to electrical stimulation.

OBJECTIVE: To investigate the effects of histamine receptor antagonists on vasoconstriction induced by electrical stimulation (ES) on posterior auricular nerve, and to explore the pre- and post-synaptic effects of sympathetic histamine on the vasomotor responses of vascular smooth muscle in rabbit ear. METHODS: ES was applied to posterior auricular nerves of the whole rabbit ear at 10 Hz, 20 Hz and 40 Hz, respectively. Besides, the whole ear was perfused with different histamine receptor antagonists under constant perfusion pressure, and the changes in the flow rate of perfusate were observed. RESULTS: The flow rate of venous outflow was decreased by ES at all the 3 frequencies. The ES-induced vasoconstriction at 20 Hz and 40 Hz could be partly inhibited by H(1) receptor antagonist chlorpheniramine (P < 0.05). After exhaustion of histamine in mast cells by pretreatment with specific mast cell degranulator compound 48/80, chlorpheniramine could still inhibit the ES-induced flow rate reduction. In contrast, H(2) receptor antagonist cimetidine could enhance the 40-Hz ES-induced flow rate reduction (P < 0.05). Moreover, ES-induced vasoconstriction at the 3 frequencies could all be enhanced by H(3) receptor antagonist thioperamide (P < 0.05). CONCLUSION: Stimulation on the auricular nerve may evoke histamine release from sympathetic nerves rather than from mast cells. Moreover, the functions of sympathetic histamine vary from pre-synaptic modulation to post-synaptic vasoconstriction or vasodilatation, via activation of different histamine receptors.

Restoration of antibiotic susceptibility in methicillin-resistant Staphylococcus aureus by targeting mecR1 with a phosphorothioate deoxyribozyme.

1. Methicillin resistance in Staphylococcus aureus is mediated by the mecA gene. The mecA gene encodes a penicillin-binding protein (PBP2a) possessing low beta-lactam affinity. Transcription of mecA is regulated by a signal transduction system consisting of the sensor/transducer MecR1. Disruption of the MecR1 regulatory pathway may inhibit mecA expression and restore methicillin-resistant Staphylococcus aureus (MRSA) susceptibility to beta-lactams. 2. In the present study, a phosphorothioate deoxyribozyme (named PS-DRz147) specifically targeting MecR1 mRNA was designed, synthesised and introduced into the MRSA strain WHO-2. 3. The expression of mecR1 and mecA was inhibited by PS-DRz147 in a concentration-dependent manner. Consequently, the susceptibility of WHO-2 colonies to the antibiotic oxacillin was restored. 4. The results of the present study indicate that blockade of the MecR1-MecI-MecA signalling pathway with an mecR1-targeted DNAzyme can restore the susceptibility of MRSA to existing beta-lactam antibiotics.