Side Chain-Modified Benzothiazinone Derivatives with Anti-Mycobacterial Activity.

Tuberculosis (TB) is a leading infectious disease with serious antibiotic resistance. The benzothiazinone (BTZ) scaffold PBTZ169 kills Mycobacterium tuberculosis (Mtb) through the inhibition of the essential cell wall enzyme decaprenylphosphoryl-ß-D-ribose 2'-oxidase (DprE1). PBTZ169 shows anti-TB potential in animal models and pilot clinical tests. Although highly potent, the BTZ type DprE1 inhibitors in general show extremely low aqueous solubility, which adversely affects the drug-like properties. To improve the compounds physicochemical properties, we generated a series of BTZ analogues. Several optimized compounds had MIC values against Mtb lower than 0.01 µM. The representative compound 37 displays improved solubility and bioavailability compared to the lead compound. Additionally, compound 37 shows Mtb-killing ability in an acute infection mouse model.

Single Escherichia coli bacteria detection using a chemiluminescence digital microwell array chip.

Rapid and sensitive Escherichia coli (E. coli) detection is important in determining environmental contamination, food contamination, as well as bacterial infection. Conventional methods based on bacterial culture suffer from long testing time (24 h), whereas novel nucleic acid-based and immunolabelling approaches are hindered by complicated operation, the need of complex and costly equipment, and the lack of differentiation of live and dead bacteria. Herein, we propose a chemiluminescence digital microwell array chip based on the hydrolysis of 6-Chloro-4-methylumbelliferyl-ß-D-glucuronide by the ß-D-glucuronidase in E. coli to achieve fast single bacterial fluorescence detection. Taking the advantage of the picoliter microwells, single bacteria are digitally encapsulated in these microwells, thus the accurate quantification of E. coli can be realized by counting the number of positive microwells. We also show that the chemiluminescence digital microwell array chip is not affected by the turbidity of the test samples as well as the temperature. Most importantly, our method can differentiate live and dead bacteria through bacterial proliferation and enzyme expression, which is confirmed by detecting E. coli after pH and chlorination treatment. By comparing with the standard method of plate counting, our method has comparable performance but significantly reduces the testing time from over 24 h-2 h and 4 h for qualitative and quantitative analysis, respectively. In addition, the microfluidic chip is portable and easy to operate without external pump, which is promising as a rapid and on-site platform for single E. coli analysis in water and food monitoring, as well as infection diagnosis.

A broadly applicable, stress-mediated bacterial death pathway regulated by the phosphotransferase system (PTS) and the cAMP-Crp cascade.

Recent work indicates that killing of bacteria by diverse antimicrobial classes can involve reactive oxygen species (ROS), as if a common, self-destructive response to antibiotics occurs. However, the ROS-bacterial death theory has been challenged. To better understand stress-mediated bacterial death, we enriched spontaneous antideath mutants of Escherichia coli that survive treatment by diverse bactericidal agents that include antibiotics, disinfectants, and environmental stressors, without a priori consideration of ROS. The mutants retained bacteriostatic susceptibility, thereby ruling out resistance. Surprisingly, pan-tolerance arose from carbohydrate metabolism deficiencies in ptsI (phosphotransferase) and cyaA (adenyl cyclase); these genes displayed the activity of upstream regulators of a widely shared, stress-mediated death pathway. The antideath effect was reversed by genetic complementation, exogenous cAMP, or a Crp variant that bypasses cAMP binding for activation. Downstream events comprised a metabolic shift from the TCA cycle to glycolysis and to the pentose phosphate pathway, suppression of stress-mediated ATP surges, and reduced accumulation of ROS. These observations reveal how upstream signals from diverse stress-mediated lesions stimulate shared, late-stage, ROS-mediated events. Cultures of these stable, pan-tolerant mutants grew normally and were therefore distinct from tolerance derived from growth defects described previously. Pan-tolerance raises the potential for unrestricted disinfectant use to contribute to antibiotic tolerance and resistance. It also weakens host defenses, because three agents (hypochlorite, hydrogen peroxide, and low pH) affected by pan-tolerance are used by the immune system to fight infections. Understanding and manipulating the PtsI-CyaA-Crp­mediated death process can help better control pathogens and maintain beneficial microbiota during antimicrobial treatment.

Rapid and dynamic detection of antimicrobial treatment response using spectral amplitude modulation in MZO nanostructure-modified quartz crystal microbalance.

We report a dynamic and rapid detection of the response of S. epidermidis to various antimicrobial treatments utilizing the real-time spectral amplitude modulations of the magnesium zinc oxide nanostructure-modified quartz crystal microbalance (MZOnano-QCM) biosensor. The sensor consists of a quartz crystal microbalance (QCM) with magnesium zinc oxide (MZO) nanostructures grown directly on the sensing electrode using metalorganic chemical vapor deposition (MOCVD). Combining the high sensitivity detection of bacteria provided by the MZO nanostructures with the QCM's dynamic acoustic spectrum makes a highly-sensitive dynamic biosensor well-suited for monitoring viscoelastic transitions during drug treatment compared to the QCM's conventional frequency shift signals. We demonstrated dynamically monitoring the response of S. epidermidis to various concentrations of the drug ciprofloxacin, and response to three different antimicrobials vancomycin, oxacillin, and ciprofloxacin, using spectral amplitude modulations of the MZOnano-QCM. Our results indicate that the amplitude modulations exhibit high sensitivity to S. epidermidis response to different drug treatments compared to the conventional frequency shift signals of the device, allowing for rapid determination (within 1.5 h) of the efficacy of the antimicrobial drug. The high sensitivity demonstrated by the spectral amplitude modulations is attributed to the direct relationship of these signals to the viscoelastic transitions of the bacterial cells on the device's sensing area while responding to drug treatment. This relationship is established by the Butterworth-Van-Dyke (BVD) model of the MZOnano-QCM. Standard microbiological protocols and assays were performed to determine the optimal drug dosages and the minimum inhibitory concentrations to serve as the benchmark for the sensor data.

Early stage detection of Staphylococcus epidermidis biofilm formation using MgZnO dual-gate TFT biosensor.

Early stage detection of biofilm formation is an important aspect of microbial research because once formed, biofilms show serious tolerance to antibiotics in contrast to the free-floating bacteria, which significantly increases the difficulty for clinical treatment of bacterial infections. The early stage detection technology is desired to improve the efficiency of medical treatments. In this work, we present a biosensor consisting of a magnesium zinc oxide (MZO) dual gate thin-film transistor (DGTFT) as the actuator and an MZO nanostructure (MZOnano) array coated conducting pad as the extended sensing gate for the early stage detection of Staphylococcus epidermidis (S. epidermidis) biofilm formation. S. epidermidis bacteria were cultured in vitro on the nanostructure modified sensing pad. Charge transfer occurs between microbial cells and the MZOnano during the initial bacterial adhesion stage. Such electrical signals, which represent the onset of biofilm formation, were dynamically detected by the DGTFT where the top gate electrode was connected to the extended MZOnano sensing pad and the bottom gate was used for biasing the device into the optimum characteristic region for high sensitivity and stable operation. The testing results show that a current change of ~80% is achieved after ~200 min of bacterial culturing. A crystal violet staining-based assay shows that tiny bacterial microcolonies just start to form at 200 min, and that it would take approximately 24 h to form matured biofilms. This technology enables medical professionals to act promptly on bacterial infection before biofilms get fully established.

Reactive oxygen species play a dominant role in all pathways of rapid quinolone-mediated killing.

BACKGROUND: Quinolones have been thought to rapidly kill bacteria in two ways: (i) quinolone-topoisomerase-DNA lesions stimulate the accumulation of toxic reactive oxygen species (ROS); and (ii) the lesions directly cause lethal DNA breaks. Traditional killing assays may have underestimated the ROS contribution by overlooking the possibility that ROS continue to accumulate and kill cells on drug-free agar after quinolone removal. METHODS: Quinolone-induced, ROS-mediated killing of Escherichia coli was measured by plating post-treatment samples on agar with/without anti-ROS agents. RESULTS: When E. coli cultures were treated with ciprofloxacin or moxifloxacin in the presence of chloramphenicol (to accentuate DNA-break-mediated killing), lethal activity, revealed by plating on quinolone-free agar, was inhibited by supplementing agar with ROS-mitigating agents. Moreover, norfloxacin-mediated lethality, observed with cells suspended in saline, was blocked by inhibitors of ROS accumulation and exacerbated by a katG catalase deficiency that impairs peroxide detoxification. Unlike WT cells, the katG mutant was killed by nalidixic acid or norfloxacin with chloramphenicol present and by nalidixic or oxolinic acid with cells suspended in saline. ROS accumulated after quinolone removal with cultures either co-treated with chloramphenicol or suspended in saline. Deficiencies in recA or recB reduced the protective effects of ROS-mitigating agents, supporting the idea that repair of quinolone-mediated DNA lesions suppresses the direct lethal effects of such lesions. CONCLUSIONS: ROS are the dominant factor in all modes of quinolone-mediated lethality, as quinolone-mediated primary DNA lesions are insufficient to kill without triggering ROS accumulation. ROS-stimulating adjuvants may enhance the lethality of quinolones and perhaps other antimicrobials.

Post-stress bacterial cell death mediated by reactive oxygen species.

Antimicrobial efficacy, which is central to many aspects of medicine, is being rapidly eroded by bacterial resistance. Since new resistance can be induced by antimicrobial action, highly lethal agents that rapidly reduce bacterial burden during infection should help restrict the emergence of resistance. To improve lethal activity, recent work has focused on toxic reactive oxygen species (ROS) as part of the bactericidal activity of diverse antimicrobials. We report that when Escherichia coli was subjected to antimicrobial stress and the stressor was subsequently removed, both ROS accumulation and cell death continued to occur. Blocking ROS accumulation by exogenous mitigating agents slowed or inhibited poststressor death. Similar results were obtained with a temperature-sensitive mutational inhibition of DNA replication. Thus, bacteria exposed to lethal stressors may not die during treatment, as has long been thought; instead, death can occur after plating on drug-free agar due to poststress ROS-mediated toxicity. Examples are described in which (i) primary stress-mediated damage was insufficient to kill bacteria due to repair; (ii) ROS overcame repair (i.e., protection from anti-ROS agents was reduced by repair deficiencies); and (iii) killing was reduced by anti-oxidative stress genes acting before stress exposure. Enzymatic suppression of poststress ROS-mediated lethality by exogenous catalase supports a causal rather than a coincidental role for ROS in stress-mediated lethality, thereby countering challenges to ROS involvement in antimicrobial killing. We conclude that for a variety of stressors, lethal action derives, at least in part, from stimulation of a self-amplifying accumulation of ROS that overwhelms the repair of primary damage.

The Efficacy and Safety of the Chinese Herbal Formula, JTTZ, for the Treatment of Type 2 Diabetes with Obesity and Hyperlipidemia: A Multicenter Randomized, Positive-Controlled, Open-Label Clinical Trial.

BACKGROUND AND AIM: Studies have shown an increasing number of type 2 diabetes (T2D) patients with concomitant obesity and hyperlipidemia syndromes, resulting from relevant metabolic disorders. However, there are few medications and therapies, which can thoroughly address these issues. Therefore, the current study evaluated the efficacy and safety of using JTTZ, a Chinese herbal formula, to treat T2D with obesity and hyperlipidemia. METHODS: A total of 450 participants with T2D (HbA1c ≥ 7.0%; waist circumference ≥ 90 cm and 80 cm in males and females, resp.; and triglycerides (TG) ≥ 1.7 mmol/L) were randomly assigned, in equal proportions, to two groups in this multicenter randomized, positive-controlled, open-label trial. One group received JTTZ formula, and the other received metformin (MET) for 12 consecutive weeks. The primary efficacy outcomes were changes in HbA1c, TG, weight, and waist circumference. Adverse reactions and hypoglycemia were monitored. RESULTS: HbA1c decreased by 0.75 ± 1.32% and 0.71 ± 1.2% in the JTTZ and MET groups, respectively, after 12 weeks of treatment. TG levels in the JTTZ and MET groups were reduced by 0.64 ± 2.37 mmol/L and 0.37 ± 2.18 mmol/L, respectively. Weight was decreased by 2.47 ± 2.71 kg in the JTTZ group and by 2.03 ± 2.36 kg in the MET group. JTTZ also appeared to alleviate insulin resistance and increase HOMA-ß. In addition, symptoms were significantly relieved in participants in the JTTZ group compared to those in the MET group. One case of hypoglycemia was reported in the MET group. No severe adverse events were reported in either group. CONCLUSIONS: The JTTZ formula led to safe and significant improvements in the blood glucose, blood lipids, and weight levels; relieved symptoms; and enhanced ß cell function for T2D patients with obesity and hyperlipidemia. The JTTZ formula has shown that it could potentially be developed as an alternative medicine for patients with T2D, particularly those who cannot tolerate metformin or other hypoglycemic drugs. This trial was registered with Clinicaltrials.gov NCT01471275.

Suppression of Reactive Oxygen Species Accumulation Accounts for Paradoxical Bacterial Survival at High Quinolone Concentration.

When bacterial cells are exposed to increasing concentrations of quinolone-class antibacterials, survival drops, reaches a minimum, and then recovers, sometimes to 100%. Despite decades of study, events underlying this paradoxical high-concentration survival remain obscure. Since reactive oxygen species (ROS) have been implicated in antimicrobial lethality, conditions generating paradoxical survival were examined for diminished ROS accumulation. Escherichia coli cultures were treated with various concentrations of nalidixic acid, followed by measurements of survival, rate of protein synthesis, and ROS accumulation. The last measurement used a dye (carboxy-H2DCFDA) that fluoresces in the presence of ROS; fluorescence was assessed by microscopy (individual cells) and flow cytometry (batch cultures). High, nonlethal concentrations of nalidixic acid induced lower levels of ROS than moderate, lethal concentrations. Sublethal doses of exogenous hydrogen peroxide became lethal and eliminated the nalidixic acid-associated paradoxical survival. Thus, quinolone-mediated lesions needed for ROS-executed killing persist at high, nonlethal quinolone concentrations, thereby implicating ROS as a key factor in cell death. Chloramphenicol suppressed nalidixic acid-induced ROS accumulation and blocked lethality, further supporting a role for ROS in killing. Nalidixic acid also inhibited protein synthesis, with extensive inhibition at high concentrations correlating with lower ROS accumulation and paradoxical survival. A catalase deficiency, which elevated ROS levels, overcame the inhibitory effect of chloramphenicol on nalidixic acid-mediated killing, emphasizing the importance of ROS. The data collectively indicate that ROS play a dominant role in the lethal action of narrow-spectrum quinolone-class compounds; a drop in ROS levels accounted for the quinolone tolerance observed at very high concentrations.

Contribution of reactive oxygen species to thymineless death in Escherichia coli.

Nutrient starvation usually halts cell growth rather than causing death. Thymine starvation is exceptional, because it kills cells rapidly. This phenomenon, called thymineless death (TLD), underlies the action of several antibacterial, antimalarial, anticancer, and immunomodulatory agents. Many explanations for TLD have been advanced, with recent efforts focused on recombination proteins and replication origin (oriC) degradation. Because current proposals account for only part of TLD and because reactive oxygen species (ROS) are implicated in bacterial death due to other forms of harsh stress, we investigated the possible involvement of ROS in TLD. Here, we show that thymine starvation leads to accumulation of both single-stranded DNA regions and intracellular ROS, and interference with either event protects bacteria from double-stranded DNA breakage and TLD. Elevated levels of single-stranded DNA were necessary but insufficient for TLD, whereas reduction of ROS to background levels largely abolished TLD. We conclude that ROS contribute to TLD by converting single-stranded DNA lesions into double-stranded DNA breaks. Participation of ROS in the terminal phases of TLD provides a specific example of how ROS contribute to stress-mediated bacterial self-destruction.

Dimethyl Sulfoxide Protects Escherichia coli from Rapid Antimicrobial-Mediated Killing.

The contribution of reactive oxygen species (ROS) to antimicrobial lethality was examined by treating Escherichia coli with dimethyl sulfoxide (DMSO), an antioxidant solvent frequently used in antimicrobial studies. DMSO inhibited killing by ampicillin, kanamycin, and two quinolones and had little effect on MICs. DMSO-mediated protection correlated with decreased ROS accumulation and provided evidence for ROS-mediated programmed cell death. These data support the contribution of ROS to antimicrobial lethality and suggest caution when using DMSO-dissolved antimicrobials for short-time killing assays.

Resveratrol Antagonizes Antimicrobial Lethality and Stimulates Recovery of Bacterial Mutants.

Reactive oxygen species (ROS; superoxide, peroxide, and hydroxyl radical) are thought to contribute to the rapid bactericidal activity of diverse antimicrobial agents. The possibility has been raised that consumption of antioxidants in food may interfere with the lethal action of antimicrobials. Whether nutritional supplements containing antioxidant activity are also likely to interfere with antimicrobial lethality is unknown. To examine this possibility, resveratrol, a popular antioxidant dietary supplement, was added to cultures of Escherichia coli and Staphylococcus aureus that were then treated with antimicrobial and assayed for bacterial survival and the recovery of mutants resistant to an unrelated antimicrobial, rifampicin. Resveratrol, at concentrations likely to be present during human consumption, caused a 2- to 3-fold reduction in killing during a 2-hr treatment with moxifloxacin or kanamycin. At higher, but still subinhibitory concentrations, resveratrol reduced antimicrobial lethality by more than 3 orders of magnitude. Resveratrol also reduced the increase in reactive oxygen species (ROS) characteristic of treatment with quinolone (oxolinic acid). These data support the general idea that the lethal activity of some antimicrobials involves ROS. Surprisingly, subinhibitory concentrations of resveratrol promoted (2- to 6-fold) the recovery of rifampicin-resistant mutants arising from the action of ciprofloxacin, kanamycin, or daptomycin. This result is consistent with resveratrol reducing ROS to sublethal levels that are still mutagenic, while the absence of resveratrol allows ROS levels to high enough to kill mutagenized cells. Suppression of antimicrobial lethality and promotion of mutant recovery by resveratrol suggests that the antioxidant may contribute to the emergence of resistance to several antimicrobials, especially if new derivatives and/or formulations of resveratrol markedly increase bioavailability.

Moving forward with reactive oxygen species involvement in antimicrobial lethality.

Support for the contribution of reactive oxygen species (ROS) to antimicrobial lethality has been refined and strengthened. Killing by diverse antimicrobials is enhanced by defects in genes that protect against ROS, inhibited by compounds that block hydroxyl radical accumulation, and is associated with surges in intracellular ROS. Moreover, support has emerged for a genetic pathway that controls the level of ROS. Since some antimicrobials kill in the absence of ROS, ROS must add to, rather than replace, known killing mechanisms. New work has addressed many of the questions concerning the specificity of dyes used to detect intracellular ROS and the specificity of perturbations that influence ROS surges. However, complexities associated with killing under anaerobic conditions remain to be resolved. Distinctions among primary lesion formation, resistance, direct lesion-mediated killing and a self-destructive stress response are discussed to facilitate efforts to potentiate ROS-mediated bacterial killing and improve antimicrobial efficacy.

[Effect of triptolide on the expression of RANTES in the renal tissue of diabetic nephropathy rats].

OBJECTIVE: To investigate the effect of triptolide (TPL) on the renal tissue of diabetic rats and its possible mechanisms. METHODS: SD rats were randomly divided into the normal control group (as the normal group), the diabetic model group (the model group), the low dose TPL treatment group (the low dose TPL group, TPL 0.2 mg/kg by gastrogavage), the high dose TPL treatment group (the high dose TPL group, TPL 0.4 mg/kg by gastrogavage). Equal volume of normal saline was given to rats in the normal group and the model group. Five rats were randomly selected from each group at week 4, 8, and 12 of the experiment to detect body weight, kidney weight, 24 h urinary albumin (24 h UAL), plasma glucose (FBG), total cholesterol (TC), total triglyeride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), white blood cell (WBC), and hemoglobin A1c (HbA1c). The mRNA and protein expression of regulated upon activation normal T-cell expressed and secreted (RANTES) in the renal tissue was assessed by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA). The renal tissue was pathologically stained by HE, PAS, and Masson staining. The glomerular and renal tubular interstitial lesions were observed at each time point. The glomerular sclerosis index (GSI) was observed by PAS staining, and the renal interstitial filrosis index (RIFI) was calcutated. RESULTS: Compared with the same group at week 4, the expression of 24 h UAL, RANTES, GSI, and RIFI at week 12 significantly decreased in two TPL groups (P <0.01). Compared with the same group at week 8, the expression of 24 h UAL, RANTES, GSI, and RIFI at week 12 also significantly decreased in the two TPL groups (P <0. 05, P <0.01). Compared with the normal group, body weight and the kidney weight obviously decreased at week 4, 8, and 12 in the model group (P <0. 01); 24 h UAL, FBG, TG, TC, HbA1c, RANTES, GSI, and RIFI were obviously elevated (P <0.01). Compared with the model group, 24 h UAL, RANTES, GSI, and RIFI also decreased in the two TPL treatment groups (P <0.01). Compared with the low dose TPL group, they were attenuated in the high dose TPL group (P <0. 05, P <0. 01). CONCLUSION: TPL could not only inhibit the over-expression of RANTES, but also improve the glomerular sclerosis and renal interstitial fibrosis in the renal tissue of diabetic rats.

Ribosomal elongation factor 4 promotes cell death associated with lethal stress.

UNLABELLED: Ribosomal elongation factor 4 (EF4) is highly conserved among bacteria, mitochondria, and chloroplasts. However, the EF4-encoding gene, lepA, is nonessential and its deficiency shows no growth or fitness defect. In purified systems, EF4 back-translocates stalled, posttranslational ribosomes for efficient protein synthesis; consequently, EF4 has a protective role during moderate stress. We were surprised to find that EF4 also has a detrimental role during severe stress: deletion of lepA increased Escherichia coli survival following treatment with several antimicrobials. EF4 contributed to stress-mediated lethality through reactive oxygen species (ROS) because (i) the protective effect of a ΔlepA mutation against lethal antimicrobials was eliminated by anaerobic growth or by agents that block hydroxyl radical accumulation and (ii) the ΔlepA mutation decreased ROS levels stimulated by antimicrobial stress. Epistasis experiments showed that EF4 functions in the same genetic pathway as the MazF toxin, a stress response factor implicated in ROS-mediated cell death. The detrimental action of EF4 required transfer-messenger RNA (tmRNA, which tags truncated proteins for degradation and is known to be inhibited by EF4) and the ClpP protease. Inhibition of a protective, tmRNA/ClpP-mediated degradative activity would allow truncated proteins to indirectly perturb the respiratory chain and thereby provide a potential link between EF4 and ROS. The connection among EF4, MazF, tmRNA, and ROS expands a pathway leading from harsh stress to bacterial self-destruction. The destructive aspect of EF4 plus the protective properties described previously make EF4 a bifunctional factor in a stress response that promotes survival or death, depending on the severity of stress. IMPORTANCE: Translation elongation factor 4 (EF4) is one of the most conserved proteins in nature, but it is dispensable. Lack of strong phenotypes for its genetic knockout has made EF4 an enigma. Recent biochemical work has demonstrated that mild stress may stall ribosomes and that EF4 can reposition stalled ribosomes to resume proper translation. Thus, EF4 protects cells from moderate stress. Here we report that EF4 is paradoxically harmful during severe stress, such as that caused by antimicrobial treatment. EF4 acts in a pathway that leads to excessive accumulation of reactive oxygen species (ROS), thereby participating in a bacterial self-destruction that occurs when cells cannot effectively repair stress-mediated damage. Thus, EF4 has two opposing functions-at low-to-moderate levels of stress, the protein is protective by allowing stress-paused translation to resume; at high-levels of stress, EF4 helps bacteria self-destruct. These data support the existence of a bacterial live-or-die response to stress.

Induction of a laccase Lcc9 from Coprinopsis cinerea by fungal coculture and its application on indigo dye decolorization.

A fungal coculture system comprised of Coprinopsis cinerea Okayama 7 (#130) and Gongronella sp. w5 produced 900 times higher laccase activity than that in pure culture. A fungal laccase named Lcc9 was induced from C. cinerea for the first time by coculture. Lcc9 was purified, characterized, and found to have high activity toward phenolic substrates at the optimum pH of 6.5 and temperature of 60°C. The laccase was stable at alkaline pH values, and its activity was not significantly affected by cations and organic solvents. Lcc9 showed decolorization capability toward indigo dye in the presence of 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonate), with 75% of indigo was decolorized by 50 U/L enzyme after 1h of incubation under optimal catalytic conditions. These results showed that fungal coculture could active silent laccase gene, and the unusual properties make Lcc9 a candidate for specific industrial and environmental applications.

Chinese herbal medicine Tianqi reduces progression from impaired glucose tolerance to diabetes: a double-blind, randomized, placebo-controlled, multicenter trial.

CONTEXT: Living in a prediabetes state significantly increases a patient's risk for both diabetes and cardiovascular disease. Tianqi capsule, containing 10 Chinese herbal medicines, is used in China for the treatment of type 2 diabetes mellitus (T2DM). OBJECTIVE: The purpose of this study was to assess whether Tianqi prevented T2DM in subjects with impaired glucose tolerance (IGT) over the course of a 12-month treatment. METHODS: Individuals with IGT were randomly allocated in a double-blind manner to receive Tianqi (n = 210) or a placebo (n = 210) for 12 months. Oral glucose tolerance tests were conducted every 3 months to assess the development of diabetes or restoration to normal glucose tolerance. All subjects received the same lifestyle education. The primary endpoint was the conversion of IGT to T2DM. Body weight and body mass index were observed. Adverse effects were monitored. RESULTS: Of the 420 enrolled subjects with IGT, 389 completed the trial (198 in the Tianqi group and 191 in the placebo group). At the end of the 12-month trial, 36 subjects in the Tianqi group (18.18%) and 56 in the placebo group (29.32%) had developed diabetes (P = .01). There was a significant difference in the number of subjects who had normal glucose tolerance at the end of the study between the Tianqi and placebo groups (n = 125, 63.13%, and n = 89, 46.60%, respectively; P = .001). Cox's proportional hazards model analysis showed that Tianqi reduced the risk of diabetes by 32.1% compared with the placebo. No severe adverse events occurred in the trial. There were no statistical differences in body weight and body mass index changes between the Tianqi group and the placebo group during the 12-month trial. CONCLUSIONS: Treatment with a Tianqi capsule for 12 months significantly decreased the incidence of T2DM in subjects with IGT, and this herbal drug was safe to use.

Cyclic di-GMP mediates Mycobacterium tuberculosis dormancy and pathogenecity.

Dormancy of Mycobacterium tuberculosis is likely to be a major cause of extended chemotherapeutic regimens and wide prevalence of tuberculosis. The molecular mechanisms underlying M. tuberculosis dormancy are not well understood. In this study, single-copy genes responsible for synthesis (dgc) and degradation (pde) of the ubiquitous bacterial second messenger, cyclic di-GMP (c-di-GMP), were deleted in the virulent M. tuberculosis strain H37Rv to generate dgc(mut) and Δpde, respectively. Under aerobic growth conditions, the two mutants and wild-type cells showed similar phenotypes. However, dgc(mut) and Δpde exhibited increased and reduced dormancy, respectively, in both anaerobiosis-triggered and vitamin C-triggered in vitro dormancy models, as determined by survival and growth recovery from dormancy. The transcriptomes of aerobic cultures of dgc(mut) and wild-type H37Rv exhibited no difference, whereas those of anaerobic cultures showed a significant difference with 61 genes that are not a part of the dosR regulon. Furthermore, Δpde but not dgc(mut) showed decreased infectivity with human THP-1 cells. Δpde also showed attenuated pathogenicity in a C57BL/6 mouse infection model. These findings are explained by c-di-GMP-mediated signaling negatively regulating M. tuberculosis dormancy and pathogenicity.

The LuxR family regulator Rv0195 modulates Mycobacterium tuberculosis dormancy and virulence.

Tuberculosis is a leading global killer that has not been effectively controlled to date. The ability of the causative agent, Mycobacterium tuberculosis, to become dormant is one of the major reasons for extended chemotherapeutic regimens and wide epidemicity. The underlying mechanisms of M. tuberculosis dormancy are not fully understood. In the present work, a LuxR family transcription factor gene, Rv0195, was deleted in the virulent M. tuberculosis strain H37Rv. Rv0195 deletion did not affect bacterial growth and long-term survival under aerobiosis but decreased cell survival and the ability to rapidly recover from dormancy in an in vitro anaerobiosis model. The deletion also reduced intracellular survivability under hypoxic and reductive stress triggered by vitamin C. Microarray hybridization analysis showed that Rv0195 affected the expression of more than 180 genes under anaerobiosis, and these genes did not overlap with the known anaerobiosis-up-regulated DosR regulon genes. Furthermore, the Rv0195 deletion diminished bacterial virulence in human macrophage-like cells and resulted in reduced bacterial survival and pathogenicity in a C57BL/6 mouse infection model. These findings offer a novel insight into the mechanisms by which M. tuberculosis adapts to and recovers from dormancy and demonstrate that the dormancy regulator Rv0195 contributes to bacterial virulence.

Phylogenetic analysis of bacterial community in the gut of American cockroach (Periplaneta americana).

OBJECTIVE: The present study was to fully evaluate the intestinal bacterial community of Periplaneta americana, an important model to study insects. METHODS: We investigated the bacterial community of P. americana gut by culture-independent methods, involving constructing the 16S rRNA gene library and microbial diversity analysis. RESULTS: The phylotypes were affiliated with Proteobacteria (66.4%), Bacteroidetes (17.8%), Firmicutes (14.5%), Fusobacteria (0.6%) and unclassified bacteria (0.6%). Phylogenetic analysis shows that 15% of the sequences clustered with that from a closely related omnivorous cockroach; and 59% clustered with that from more distantly related animals, including omnivorous, herbivorous, and carnivorous animals, which differ greatly in feeding habits. Moreover, 18% of the clones showed high sequence identity with potential pathogens closely related to human diseases, which also reinforces the concept of the cockroach as a carrier of pathogens. CONCLUSION: Due to their habits of feeding on a variety of foodstuffs, omnivorous cockroaches harbor a large and diverse microbial community in the gut. The host phylogeny and dietary habits might be critical for the intestinal bacterial community composition of cockroaches.