Efflux pumps of Mycobacterium tuberculosis play a significant role in antituberculosis activity of potential drug candidates

Active efflux of drugs mediated by efflux pumps that confer drug resistance is one of the mechanisms developed by bacteria to counter the adverse effects of antibiotics and chemicals. To understand these efflux mechanisms in Mycobacterium tuberculosis, we generated knockout (KO) mutants of four efflux pumps of the pathogen belonging to different classes. We measured the MICs and kill values of two different compound classes on the wild type (WT) and the efflux pump (EP) KO mutants in the presence and absence of the efflux inhibitors verapamil and L-phenylalanyl-L-arginyl-β-naphthylamide (PAβN). Among the pumps studied, the efflux pumps belonging to the ABC (ATP-binding cassette) class, encoded by Rv1218c, and the SMR (small multidrug resistance) class, encoded by Rv3065, appear to play important roles in mediating the efflux of different chemical classes and antibiotics. Efflux pumps encoded by Rv0849 and Rv1258c also mediate the efflux of these compounds, but to a lesser extent. Increased killing is observed in WT M. tuberculosis cells by these compounds in the presence of either verapamil or PAβN. The efflux pump KO mutants were more susceptible to these compounds in the presence of efflux inhibitors. We have shown that these four efflux pumps of M. tuberculosis play a vital role in mediating efflux of different chemical scaffolds. Inhibitors of one or several of these efflux pumps could have a significant impact in the treatment of tuberculosis. The identification and characterization of Rv0849, a new efflux pump belonging to the MFS (major facilitator superfamily) class, are reported.

Epitope-specific CD4+, but not CD8+, T-cell responses induced by recombinant influenza A viruses protect against Mycobacterium tuberculosis infection

Tuberculosis remains a global health problem, in part due to failure of the currently available vaccine, BCG, to protect adults against pulmonary forms of the disease. We explored the impact of pulmonary delivery of recombinant influenza A viruses (rIAVs) on the induction of Mycobacterium tuberculosis (M. tuberculosis)-specific CD4(+) and CD8(+) T-cell responses and the resultant protection against M. tuberculosis infection in C57BL/6 mice. Intranasal infection with rIAVs expressing a CD4(+) T-cell epitope from the Ag85B protein (PR8.p25) or CD8(+) T-cell epitope from the TB10.4 protein (PR8.TB10.4) generated strong T-cell responses to the M. tuberculosis-specific epitopes in the lung that persisted long after the rIAVs were cleared. Infection with PR8.p25 conferred protection against subsequent M. tuberculosis challenge in the lung, and this was associated with increased levels of poly-functional CD4(+) T cells at the time of challenge. By contrast, infection with PR8.TB10.4 did not induce protection despite the presence of IFN-γ-producing M. tuberculosis-specific CD8(+) T cells in the lung at the time of challenge and during infection. Therefore, the induction of pulmonary M. tuberculosis epitope-specific CD4(+), but not CD8(+) T cells, is essential for protection against acute M. tuberculosis infection in the lung.

Postoperative pulmonary dysfunction in adults after cardiac surgery with cardiopulmonary bypass: clinical significance and implications for practice

Postoperative pulmonary complications are the most frequent and significant contributor to morbidity, mortality, and costs associated with hospitalization. Interestingly, despite the prevalence of these complications in cardiac surgical patients, recognition, diagnosis, and management of this problem vary widely. In addition, little information is available on the continuum between routine postoperative pulmonary dysfunction and postoperative pulmonary complications. The course of events from pulmonary dysfunction associated with surgery to discharge from the hospital in cardiac patients is largely unexplored. In the absence of evidence-based practice guidelines for the care of cardiac surgical patients with postoperative pulmonary dysfunction, an understanding of the path ophysiological basis of the development of postoperative pulmonary complications is fundamental to enable clinicians to assess the value of current management interventions. Previous research on postoperative pulmonary dysfunction in adults undergoing cardiac surgery is reviewed, with an emphasis on the pathogenesis of this problem, implications for clinical nursing practice, and possibilities for future research.

Muscle atrophy and hypertrophy signaling in patients with chronic obstructive pulmonary disease

Rationale: The molecular mechanisms of muscle atrophy in chronic obstructive pulmonary disease (COPD) are poorly understood. In wasted animals, muscle mass is regulated by several AKT-related signaling pathways.
Objectives: To measure the protein expression of AKT, forkhead box class O (FoxO)-1 and -3, atrogin-1, the phosphophrylated form of AKT, p70^S6K glycogen synthase kinase-3ß (GSK-3ß), eukaryotic translation initiation factor 4E binding protein-1 (4E-BP1), and the mRNA expression of atrogin-1, muscle ring finger (MuRF) protein 1, and FoxO-1 and -3 in the quadriceps of 12 patients with COPD with muscle atrophy and 10 healthy control subjects. Five patients with COPD with preserved muscle mass were subsequently recruited and were compared with six patients with low muscle mass.
Methods: Protein contents and mRNA expression were measured by Western blot and quantitative polymerase chain reaction, respectively.
Measurements and Main Results: The levels of atrogin-1 and MuRF1 mRNA, and of phosphorylated AKT and 4E-BP1 and FoxO-1 proteins, were increased in patients with COPD with muscle atrophy compared with healthy control subjects, whereas atrogin-1, p70^S6K, GSK-3ß, and FoxO-3 protein levels were similar. Patients with COPD with muscle atrophy showed an increased expression of p70^S6K, GSK-3ß, and 4E-BP1 compared with patients with COPD with preserved muscle mass.
Conclusions: An increase in atrogin-1 and MuRF1 mRNA and FoxO-1 protein content was observed in the quadriceps of patients with COPD. The transcriptional regulation of atrogin-1 and MuRF1 may occur via FoxO-1, but independently of AKT. The overexpression of the muscle hypertrophic signaling pathways found in patients with COPD with muscle atrophy could represent an attempt to restore muscle mass.

Herb-drug interactions: a literature review

Herbs are often administered in combination with therapeutic drugs, raising the potential of herb-drug interactions. An extensive review of the literature identified reported herb-drug interactions with clinical significance, many of which are from case reports and limited clinical observations.
Cases have been published reporting enhanced anticoagulation and bleeding when patients on long-term warfarin therapy also took Salvia miltiorrhiza (danshen). Allium sativum (garlic) decreased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration of saquinavir, but not ritonavir and paracetamol (acetaminophen), in volunteers. A. sativum increased the clotting time and international normalised ratio of warfarin and caused hypoglycaemia when taken with chlorpropamide. Ginkgo biloba (ginkgo) caused bleeding when combined with warfarin or aspirin (acetylsalicylic acid), raised blood pressure when combined with a thiazide diuretic and even caused coma when combined with trazodone in patients. Panax ginseng (ginseng) reduced the blood concentrations of alcohol (ethanol) and warfarin, and induced mania when used concomitantly with phenelzine, but ginseng increased the efficacy of influenza vaccination. Scutellaria baicalensis (huangqin) ameliorated irinotecan-induced gastrointestinal toxicity in cancer patients.
Piper methysticum (kava) increased the 'off' periods in patients with parkinsonism taking levodopa and induced a semicomatose state when given concomitantly with alprazolam. Kava enhanced the hypnotic effect of alcohol in mice, but this was not observed in humans. Silybum marianum (milk thistle) decreased the trough concentrations of indinavir in humans. Piperine from black (Piper nigrum Linn) and long (P. longum Linn) peppers increased the AUC of phenytoin, propranolol and theophylline in healthy volunteers and plasma concentrations of rifamipicin (rifampin) in patients with pulmonary tuberculosis. Eleutheroccus senticosus (Siberian ginseng) increased the serum concentration of digoxin, but did not alter the pharmacokinetics of dextromethorphan and alprazolam in humans. Hypericum perforatum (hypericum; St John's wort) decreased the blood concentrations of ciclosporin (cyclosporin), midazolam, tacrolimus, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline, but did not alter the pharmacokinetics of carbamazepine, pravastatin, mycophenolate mofetil and dextromethorphan. Cases have been reported where decreased ciclosporin concentrations led to organ rejection. Hypericum also caused breakthrough bleeding and unplanned pregnancies when used concomitantly with oral contraceptives. It also caused serotonin syndrome when used in combination with selective serotonin reuptake inhibitors (e.g. sertraline and paroxetine).
In conclusion, interactions between herbal medicines and prescribed drugs can occur and may lead to serious clinical consequences. There are other theoretical interactions indicated by preclinical data. Both pharmacokinetic and/or pharmacodynamic mechanisms have been considered to play a role in these interactions, although the underlying mechanisms for the altered drug effects and/or concentrations by concomitant herbal medicines are yet to be determined. The clinical importance of herb-drug interactions depends on many factors associated with the particular herb, drug and patient. Herbs should be appropriately labeled to alert consumers to potential interactions when concomitantly used with drugs, and to recommend a consultation with their general practitioners and other medical carers.

Variable definitions: implications for the prediction of pulmonary complications after adult cardiac surgery

Aim: The aim of this paper was to review the implications that variable definitions have for the prediction of post-operative pulmonary complications after cardiac surgery.

Method: A review of the literature from 1980 to 2002. Selected studies demonstrated an original attempt to examine multivariate associations between pre, intra or post-operative antecedents and pulmonary outcomes in patients undergoing coronary artery bypass grafting (CABG). Reports that described the validation of established clinical prediction rules, testing interventions or research conducted in non-human cohorts were excluded from this review.

Results: Consistently, variable factor and outcome definitions are combined for the development of multivariate prediction models that subsequently have limited clinical value. Despite being prevalent there are very few attempts to examine post-operative pulmonary complications (PPC) as endpoints in isolation. The trajectory of pulmonary dysfunction that precedes complications in the post-operative context is not clear. As such there is little knowledge of post-operative antecedents to PPC that are invariably excluded from model development.

Conclusion: Multivariate clinical prediction rules that incorporate antecedent patient and process factors from the continuum of cardiovascular care for specific pulmonary outcomes are recommended. Models such as these would be useful for practice, policy and quality improvement.

Neurally-derived nitric oxide regulates vascular tone in pulmonary and cutaneous arteries of the toad, Bufo marinus

In this study, the role of nitric oxide (NO) in regulation of the pulmocutaneous vasculature of the toad, Bufo marinus was investigated. In vitro myography demonstrated the presence of a neural NO signaling mechanism in both arteries. Vasodilation induced by nicotine was inhibited by the soluble guanylyl cyclase (GC) inhibitor, 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one, and the NO synthase (NOS) inhibitor, N^ω-nitro-_L-arginine (_L-NNA). Removal of the endothelium had no significant effect on the vasodilation. Furthermore, pretreatment with N⁵-(1-imino-3-butenyl)-_L-ornithine (vinyl-_L-NIO), a more specific inhibitor of neural NOS, caused a significant decrease in the nicotine-induced dilation. In the pulmonary artery only, a combination of _L-NNA and the calcitonin gene-related peptide (CGRP) receptor antagonist, CGRP(_8-37), completely blocked the nicotine-induced dilation. In both arteries, the vasodilation was also significantly decreased by glibenclamide, an ATP-sensitive K⁺ (K⁺_ATP) channel inhibitor. Levcromakalim, a K⁺_ATP channel opener, caused a dilation that was blocked by glibenclamide in both arteries. In the pulmonary artery, NO donor-mediated dilation was significantly decreased by pretreatment with glibenclamide. The physiological data were supported by NADPH-diaphorase histochemistry and immunohistochemistry, which demonstrated NOS in perivascular nerve fibers but not the endothelium of the arteries. These results indicate that the pulmonary and cutaneous arteries of B. marinus are regulated by NO from nitrergic nerves rather than NO released from the endothelium. The nitrergic vasodilation in the arteries appears to be caused, in part, via activation of K⁺_ATP channels. Thus, NO could play an important role in determining pulmocutaneous blood flow and the magnitude of cardiac shunting.

Factors affecting the offer of pulmonary rehabilitation to patients with chronic obstructive pulmonary disease by primary care professionals : a qualitative study

Aim: To explore health professionals’ experiences of barriers and facilitators to referring patients for pulmonary rehabilitation in a primary care setting.

Background: Pulmonary rehabilitation involves a multidisciplinary teamwork approach to improving
the quality of life for people with chronic obstructive pulmonary disease. This study aimed to find out about health care professionals’ experiences when referring patients. Reports suggest that a health care professional’s attitude towards a treatment affects the willingness of patients to accept advice.

Methods: Five focus group interviews were undertaken with 21 health professionals from North Midlands, UK. Data were analysed using a thematic analysis drawing on the techniques of grounded theory.

Findings: Chronic disease management has been delegated to Practice Nurses in many cases leaving some nurses feeling unsupported and some General Practitioners feeling deskilled. Problems with communication, a lack of adequate and timely local service provision, a difficult referral process, time pressures and lack of information were barriers to health care professionals making an offer of pulmonary rehabilitation. An explanatory model is proposed to describe how addressing barriers to referral may improve health care professionals views about pulmonary rehabilitation and therefore may mean that they present it in a more positive manner.

Improving the uptake of pulmonary rehabilitation in patients with COPD : qualitative study of experiences and attitudes

Background
Pulmonary rehabilitation can improve the quality of life and ability to function of patients with chronic obstructive pulmonary disease (COPD). It may also reduce hospital admission and inpatient stay with exacerbations of COPD. Some patients who are eligible for pulmonary rehabilitation may not accept an offer of it, thereby missing an opportunity to improve their health status.

Aim
To identify a strategy for improving the uptake of pulmonary rehabilitation.

Design of study
Qualitative interviews with patients.

Setting
Patients with COPD were recruited from a suburban general practice in north-east Derbyshire, UK.

Method
In-depth interviews were conducted on a purposive sample of 16 patients with COPD to assess their concerns about accepting an offer of pulmonary rehabilitation. Interviews were analysed using grounded theory.

Results
Fear of breathlessness and exercise, and the effect of pulmonary rehabilitation on coexisting medical problems were the most common concerns patients had about taking part in the rehabilitation. The possibility of reducing the sensation of breathlessness and regaining the ability to do things, such as play with their grandchildren, were motivators to participating.

Conclusion
A model is proposed where patients who feel a loss of control as their disease advances may find that pulmonary rehabilitation offers them the opportunity to regain control. Acknowledging patients' fears and framing pulmonary rehabilitation as a way of ‘regaining control’ may improve patient uptake.

Hybrid classification of pulmonary nodules

Automated classification of lung nodules is challenging because of the variation in shape and size of lung nodules, as well as their associated differences in their images. Ensemble based learners have demonstrated the potentialof good performance. Random forests are employed for pulmonary nodule classification where each tree in the forest produces a classification decision, and an integrated output is calculated. A classification aided by clustering approach is proposed to improve the lung nodule classification performance. Three experiments are performed using the LIDC lung image database of 32 cases. The classification performance and execution times are presented and discussed.

Pulmonary nodule classification aided by clustering

Lung nodules can be detected through examining CT scans. An automated lung nodule classification system is presented in this paper. The system employs random forests as it base classifier. A unique architecture for classification-aided-by-clustering is presented. Four experiments are conducted to study the performance of the developed system. 5721 CT lung image slices from the LIDC database are employed in the experiments. According to the experimental results, the highest sensitivity of 97.92%, and specificty of 96.28% are achieved by the system. The results demonstrate that the system has improved the performances of its tested counterparts.

Antecedents to postoperative pulmonary dysfunction in adults after cardiac surgery

The previously unexplored trajectory of postoperative pulmonary dysfunction was mapped in adults having cardiac surgery. Factors including hypoxaemia, positive fluid balance, severe pain and impaired functional status were associated with the development of pulmonary dysfunction and pneumonia. These antecedents are amenable to treatment in the form of prompt preventative nursing intervention that has a fundamental influence on patient outcome.