2871713
Removal of carbonaceous and nitrogenous pollutants from a synthetic wastewater using a membrane-coupled bioreactor
Two modified Ludzack-Ettinger (MLE)-type membrane-coupled bioreactors (MBRs) were investigated in this study for the purpose of removing both nitrogenous and carbonaceous pollutants from a synthetic wastewater. During the first MBR experiment, removal efficiencies were high (>90%) for chemical oxygen demand (COD) and ammonia, but total nitrogenous pollutant removal efficiency was poor (~25%). Bacterial community analysis of ammonia oxidizing bacteria (AOB) by a nested PCR-DGGE approach detected two Nitrosomonas-like populations and one Nitrosospira-like population. During the initial portion of the second MBR experiment, COD and ammonia removal efficiencies were similar to the first MBR experiment until the COD of the influent wastewater was increased to provide additional electron donors to support denitrification. Total nitrogen removal efficiencies eventually exceeded 90%, with a hydraulic residence time (HRT) of 24 h and a recirculation ratio of 8. When the HRT of the MBR experiment was decreased to 12 h, however, ammonia removal efficiency was adversely affected. A subsequent increase in the HRT to 18 h helped improve removal efficiencies for both ammonia (>85%) and total nitrogenous compounds (~70%). Our research demonstrates that MBRs can be effectively designed to remove both carbonaceous and nitrogenous pollutants. The ability of the microbial community to switch between anoxic (denitrifying) and oxic (nitrifying) conditions, however, represents a critical process constraint for the application of MLE-type MBR systems, such that little benefit is gained compared to conventional designs.
21394365
Chlorinated phenols control the expression of the multidrug resistance efflux pump MexAB-OprM in Pseudomonas aeruginosa by interacting with NalC.
NalC is a TetR type regulator that represses the multidrug efflux pump MexAB-OprM in Pseudomonas aeruginosa. Here we explain the mechanism of NalC-mediated regulation of MexAB-OprM. We show that NalC non-covalently binds chlorinated phenols and chemicals containing chlorophenol side-chains such as triclosan. NalC-chlorinated phenol binding results in its dissociation from promoter DNA and upregulation of NalC's downstream targets, including the MexR antirepressor ArmR. ArmR upregulation and MexR-ArmR complex formation have previously been shown to upregulate MexAB-OprM. In vivo mexB and armR expression analyses were used to corroborate in vitro NalC-chlorinated phenol binding. We also show that the interaction between chlorinated phenols and NalC is reversible, such that removal of these chemicals restored NalC promoter DNA binding. Thus, the NalC-chlorinated phenol interaction is likely a pertinent physiological mechanism that P. aeruginosa uses to control expression of the MexAB-OprM efflux pump.
12219567
Application of rbcL based molecular diversity analysis to algae in wastewater treatment plants.
The molecular diversity of algae in the final clarifier or denitrification filter outfall from three wastewater treatment plants (WWTPs) with activated sludge based treatment was analyzed using the rbcL gene as a phylogenetic marker. The rbcL gene encodes the large subunit of the CO(2) fixing enzyme RuBisCO. Among algae identified at the WWTPs were diatoms, green algae, cyanobacteria, Eustigmatophyceae, and unknown heterokonts. A high level of diversity was observed within WWTPs with 19-24 unique rbcL sequences detected at each plant. Algae composition also varied between treatment plants. Our results show that the rbcL gene can be used as a phylogenetic marker for algae diversity analysis in a wastewater treatment context.
45692513
Sphingobacterium sp. strain PM2-P1-29 harbours a functional tet(X) gene encoding for the degradation of tetracycline.
AIMS
The tet(X) gene has previously been found in obligate anaerobic Bacteroides spp., which is curious because tet(X) encodes for a NADP-dependent monooxygenase that requires oxygen to degrade tetracycline. In this study, we characterized a tetracycline resistant, aerobic, Gram-negative Sphingobacterium sp. strain PM2-P1-29 that harbours a tet(X) gene.


METHODS AND RESULTS
Sphingobacterium sp. PM2-P1-29 demonstrated the ability to transform tetracycline compared with killed controls. The presence of the tet(X) gene was verified by PCR and nucleotide sequence analysis. Additional nucleotide sequence analysis of regions flanking the tet(X) gene revealed a mobilizable transposon-like element (Tn6031) that shared organizational features and genes with the previously described Bacteroides conjugative transposon CTnDOT. A circular transposition intermediate of the tet(X) region, characteristic of mobilizable transposons, was detected. However, we could not demonstrate the conjugal transfer of the tet(X) gene using three different recipient strains and numerous experimental conditions.


CONCLUSIONS
This study suggests that Sphingobacterium sp. PM2-P1-29 or a related bacterium may be an ancestral source of the tet(X) gene.


SIGNIFICANCE AND IMPACT OF THE STUDY
This study demonstrates the importance of environmental bacteria and lateral gene transfer in the dissemination and proliferation of antibiotic resistance among bacteria.
2929379
The effects of subtherapeutic antibiotic use in farm animals on the proliferation and persistence of antibiotic resistance among soil bacteria
The use of antibiotics at subtherapeutic concentrations for agricultural applications is believed to be an important factor in the proliferation of antibiotic-resistant bacteria. The goal of this study was to determine if the application of manure onto agricultural land would result in the proliferation of antibiotic resistance among soil bacteria. Chlortetracycline-resistant bacteria were enumerated and characterized from soils exposed to the manure of animals fed subtherapeutic concentrations of antibiotics and compared to the chlortetracycline-resistant bacteria from soils at farms with restricted antibiotic use (dairy farms) and from non-agricultural soils. No significant differences were observed at nine different study sites with respect to the numbers and types of cultivated chlortetracycline-resistant bacteria. Genes encoding for tetracycline resistance were rarely detected in the resistant bacteria from these sites. In contrast, soils collected from a tenth farm, which allowed manure to indiscriminately accumulate outside the animal pen, had significantly higher chlortetracycline-resistance levels. These resistant bacteria frequently harbored one of 14 different genes encoding for tetracycline resistance, many of which (especially tet(A) and tet(L)) were detected in numerous different bacterial species. Subsequent bacterial enumerations at this site, following the cessation of farming activity, suggested that this farm remained a hotspot for antibiotic resistance. In conclusion, we speculate that excessive application of animal manure leads to the spread of resistance to soil bacteria (potentially by lateral gene transfer), which then serve as persistent reservoir of antibiotic resistance.
11853260
Evidence for interstate transmission and increase in prevalence of bovine group B rotavirus strains with a novel VP7 genotype among diarrhoeic calves in Eastern and Northern states of India.
During a surveillance study (2003-2005) in a cattle market in Kolkata city, state of West Bengal, Eastern India, 34 (13.0%) of 260 calves with diarrhoea were positive for group B rotaviruses (GBR) by RNA electrophoresis in polyacrylamide gels. Analysis of the partial VP7 gene sequence of 28 of the 34 GBR strains revealed maximum identities (97.7-99.5% at nucleotide level and 97.8-100% at amino-acid level) with the novel bovine GBR 'Kolkata strains' reported in an earlier surveillance study (1.5%, n=192, 2001-2002) from the same cattle market, and shared low identities of 73.7-78.9% and 80.8-89.6%; 62.6-66.2% and 59.8-65.4%; 58.9-62.2% and 48.6-54.9% at nucleotide and amino-acid level with other bovine, human, and murine GBR. The GBR-infected calves were traced to districts in neighbouring states of West Bengal. Therefore, the present study reports a rapid increase in prevalence (13.0% in 2003-2005 against 1.5% in 2001-2002) of novel GBR strains among calves with diarrhoea, and provides evidence for interstate transmission of GBR.
25523214
Dissecting the correlation structure of a bivariate phenotype: Common genes or shared environment?
High correlations between two quantitative traits may be either due to common genetic factors or common environmental factors or a combination of both. In this study, we develop statistical methods to extract the genetic contribution to the total correlation between the components of a bivariate phenotype. Using data on bivariate phenotypes and marker genotypes for sib-pairs, we propose a test for linkage between a common QTL and a marker locus based on the conditional cross-sib trait correlations (trait 1 of sib 1—trait 2 of sib 2 and conversely) given the identity-by-descent (i.b.d.) sharing at the marker locus. We use Monte-Carlo simulations to evaluate the performance of the proposed test under different trait parameters and quantitative trait distributions. An application of the method is illustrated using data on two alcohol-related phenotypes from a project on the collaborative study on the genetics of alcoholism.
19067572
Long term results of surgery versus continuous hyperfractionated accelerated radiotherapy (CHART) in patients aged >70 years with stage 1 non-small cell lung cancer.
BACKGROUND
Patients with T1N0 non-small cell lung cancer (NSCLC) are preferably treated by anatomic lobectomy. However, not all such patients are suitable for lobectomy due to their age or co-morbidity. Our aim was to determine the results obtained following lobectomy, wedge resection (WR) or continuous hyperfractionated accelerated radiotherapy (CHART) in patients aged >70 years.


PATIENTS
Two hundred and fifteen consecutive patients aged >70 years, with pathologic stage 1 NSCLC in our unit between 1991 and 2001 were studied. Of these patients, 149 had a lobectomy, 47 had a WR and 19 had CHART. Follow-up was 100% complete.


RESULTS
Analysis demonstrated the WR and CHART patients to have reduced pulmonary function (FEV(1) 59% and 52%, respectively, of predicted vs. 76%, P<0.001) when compared to the lobectomy group but there were no differences among the groups with regard to mean age and histologic tumour type. There were no operative mortality among patients after WR; however, a 2.7% 30-day operative mortality among patients undergoing lobectomy (P=0.29). Kaplan-Meier survival curves at 1 and 5 years for patients undergoing WR, lobectomy and CHART was 98% and 74% vs. 97% and 68% vs. 80% and 39%, respectively (P=0.0484). The frequency of local/regional recurrence in the WR group (19.1%) was not significantly higher than in the lobectomy group (18.4%, P=0.38) when compared to the CHART group (27%, P=0.07).


CONCLUSION
Loco-regional recurrence and survival after WR and lobectomy in elderly patients with stage I NSCLC are comparable. Although the numbers are small, these data suggest that CHART is a reasonable treatment option for those who are not suitable candidates for surgery.
40019002
Prospective randomized comparative study of macular thickness following phacoemulsification and manual small incision cataract surgery.
PURPOSE
To compare macular thickness following uncomplicated phacoemulsification with foldable acrylic lens and manual small incision cataract surgery (MSICS) with non-foldable polymethyl methacrylate (PMMA) lens implantation.


METHODS
Prospective study was carried out with one eye each of 224 patients with senile cataract randomized into two groups, phacoemulsification and MSICS, by simple 1:1 randomization. Following surgery by either of the two methods, macular thickness was measured by optical coherence tomography (OCT) on the 1st, 7th, 42nd and 180th postoperative day. Main outcome measure was postoperative macular thickness.


RESULTS
On the first postoperative day, central subfield mean thickness (CSMT) in MSICS group was 192.8 +/- 17.9 microm and that in phacoemulsification group was 192.1 +/- 27.4 microm, with no significant difference (p = 0.12). On the 7th day, CSMT in MSICS group (198.9 +/- 21.4 microm) was significantly (p = 0.04) more than that in phacoemulsification group (193.1 +/- 19.3 microm). On the 42nd day, CSMT in MSICS group was 207.8 +/- 26.3 microm and that in phacoemulsification group was 198.3 +/- 23 microm, the difference being significant (p = 0.007). Clinically macular oedema was not diagnosed in any of the patients at any visit. The increase in macular thickness was sub-clinical and did not affect final visual outcome in any patient.


CONCLUSION
In spite of the greater theoretical risk of increased postoperative inflammation following MSICS, there was no evidence of cystoid macular oedema, either clinically or on OCT. However, chance of sub-clinical increase in CSMT was more following MSICS compared to phacoemulsification.
34065094
Application of L1-Norm Regularization to Epicardial Potential Solution of the Inverse Electrocardiography Problem
The electrocardiographic inverse problem of computing epicardial potentials from multi-electrode body-surface ECG measurements, is an ill-posed problem. Tikhonov regularization is commonly employed, which imposes penalty on the L2-norm of the potentials (zero-order) or their derivatives. Previous work has indicated superior results using L2-norm of the normal derivative of the solution (a first order regularization). However, L2-norm penalty function can cause considerable smoothing of the solution. Here, we use the L1-norm of the normal derivative of the potential as a penalty function. L1-norm solutions were compared to zero-order and first-order L2-norm Tikhonov solutions and to measured ‘gold standards’ in previous experiments with isolated canine hearts. Solutions with L1-norm penalty function (average relative error [RE] = 0.36) were more accurate than L2-norm (average RE = 0.62). In addition, the L1-norm method localized epicardial pacing sites with better accuracy (3.8 ± 1.5 mm) compared to L2-norm (9.2 ± 2.6 mm) during pacing in five pediatric patients with congenital heart disease. In a pediatric patient with Wolff–Parkinson–White syndrome, the L1-norm method also detected and localized two distinct areas of early activation around the mitral valve annulus, indicating the presence of two left-sided pathways which were not distinguished using L2 regularization.