Rapid in vivo assessment of drug efficacy against Mycobacterium tuberculosis using an improved firefly luciferase

Objectives

In vivo experimentation is costly and time-consuming, and presents a major bottleneck in anti-tuberculosis drug development. Conventional methods rely on the enumeration of bacterial colonies, and it can take up to 4 weeks for Mycobacterium tuberculosis to grow on agar plates. Light produced by recombinant bacteria expressing luciferase enzymes can be used as a marker of bacterial load, and disease progression can be easily followed non-invasively in live animals by using the appropriate imaging equipment. The objective of this work was to develop a bioluminescence-based mouse model of tuberculosis to assess antibiotic efficacy against M. tuberculosis in vivo.

Methods

We used an M. tuberculosis strain carrying a red-shifted derivative of the firefly luciferase gene (FFlucRT) to infect mice, and monitored disease progression in living animals by bioluminescence imaging before and after treatment with the frontline anti-tuberculosis drug isoniazid. The resulting images were analysed and the bioluminescence was correlated with bacterial counts.

Results

Using bioluminescence imaging we detected as few as 1.7 × 10³ and 7.5 × 10⁴ reporter bacteria ex vivo and in vivo, respectively, in the lungs of mice. A good correlation was found between bioluminescence and bacterial load in both cases. Furthermore, a marked reduction in luminescence was observed in living mice given isoniazid treatment.

Conclusions

We have shown that an improved bioluminescent strain of M. tuberculosis can be visualized by non-invasive imaging in live mice during an acute, progressive infection and that this technique can be used to rapidly visualize and quantify the effect of antibiotic treatment. We believe that the model presented here will be of great benefit in early drug discovery as an easy and rapid way to identify active compounds in vivo.

Reactions, beliefs and concerns associated with providing hair specimens for medical research among a South African sample: a qualitative approach

In order to optimize treatment outcome among antiretroviral therapy users, there is a strong imperative to engage in continued monitoring and maintenance of therapeutic drug levels in patients. The aim of this study was to document the perspectives, beliefs, and concerns of South African antiretroviral therapy users providing hair specimens to determine antiretroviral drug levels. Twenty-one women living with HIV were recruited from a community health center in the Western Cape. Interviews were recorded and transcribed, and analyzed using Atlas.ti version 6. Although participants identified several cultural beliefs influencing their decision to provide hair specimens for drug level measurement, nearly all agreed that they would be willing to do so if provided with enough information by the researcher.

A new in vivo model to test anti-tuberculosis drugs using fluorescence imaging

OBJECTIVES

The current method for testing new drugs against tuberculosis in vivo is the enumeration of bacteria in organs by cfu assay. Owing to the slow growth rate of Mycobacterium tuberculosis (Mtb), these assays can take months to complete. Our aim was to develop a more efficient, fluorescence-based imaging assay to test new antibiotics in a mouse model using Mtb reporter strains.

METHODS

A commercial IVIS Kinetic® system and a custom-built laser scanning system with fluorescence molecular tomography (FMT) capability were used to detect fluorescent Mtb in living mice and lungs ex vivo. The resulting images were analysed and the fluorescence was correlated with data from cfu assays.

RESULTS

We have shown that fluorescent Mtb can be visualized in the lungs of living mice at a detection limit of ∼8 × 10⁷ cfu/lung, whilst in lungs ex vivo a detection limit of ∼2 × 10⁵ cfu/lung was found. These numbers were comparable between the two imaging systems. Ex vivo lung fluorescence correlated to numbers of bacteria in tissue, and the effect of treatment of mice with the antibiotic moxifloxacin could be visualized and quantified after only 9 days through fluorescence measurements, and was confirmed by cfu assays.

CONCLUSIONS

We have developed a new and efficient method for anti-tuberculosis drug testing in vivo, based on fluorescent Mtb reporter strains. Using this method instead of, or together with, cfu assays will reduce the time required to assess the preclinical efficacy of new drugs in animal models and enhance the progress of these candidates into clinical trials against human tuberculosis.

Meta-analysis of self-reported substance use compared with laboratory substance assay in general adult mental health settings

An accurate assessment of substance use is necessary to make a correct psychiatric diagnosis and to provide appropriate treatment. This study uses meta-analysis to establish the strength of the association between self-reported substance use and the results of laboratory substance assay including the testing for specific substances and screening for any substance use in psychiatric hospitals and in community mental health settings. A systematic search for published studies was supplemented by additional data required for meta-analysis provided by several researchers in this field. Using random-effects meta-analysis, we calculated the pooled estimate of the odds ratio of a positive substance assay in patients reporting use or non-use of substances and estimated the sensitivity, specificity, positive predictive value and negative predictive value. Twenty-six studies met the inclusion criteria. Very strong associations were found between self-reported use and positive tests for cannabis [N = 11 studies, odds ratio (OR) = 22.3; 95% confidence interval (CI) = 10.1-49.1], amphetamines (N = 8, OR = 26.6; 95% CI = 7.9-88.9), cocaine (N = 8, OR = 39.7; 95% CI = 16.2-97.2) and opiates (N = 7, OR = 83.5; 95% CI = 26.7-260.7). Strong associations were found between self-reported use of any substance and positive substance screening (N = 15, OR = 7.2, 95% CI = 3.6-14.1) and tests for alcohol use (N = 5, OR = 8.5; 95% CI = 2.5-28.4). Screening for any substance use had a sensitivity of 61% and a specificity of 66%. Testing for individual substances was specific but lacked sensitivity. Screening has the potential to detect clinically relevant substances that would not be reported by the patient, whereas testing for a specific substance has little advantage over self-report. The sensitivity of the substance assay might be improved by obtaining a sample at the earliest opportunity. Consideration should be given to the increased use of substance screening in general adult mental health settings because it could improve the accuracy of psychiatric diagnosis and increase the likelihood of patients receiving treatment for substance use disorders.

Production of de novo cardiomyocytes: human pluripotent stem cell differentiation and direct reprogramming

Cardiovascular disease is a leading cause of death worldwide. The limited capability of heart tissue to regenerate has prompted methodological developments for creating de novo cardiomyocytes, both in vitro and in vivo. Beyond uses in cell replacement therapy, patient-specific cardiomyocytes may find applications in drug testing, drug discovery, and disease modeling. Recently, approaches for generating cardiomyocytes have expanded to encompass three major sources of starting cells: human pluripotent stem cells (hPSCs), adult heart-derived cardiac progenitor cells (CPCs), and reprogrammed fibroblasts. We discuss state-of-the-art methods for generating de novo cardiomyocytes from hPSCs and reprogrammed fibroblasts, highlighting potential applications and future challenges.

Drug violations and aviation accidents: findings from the US mandatory drug testing programs

AIMS

To assess the role of drug violations in aviation accidents.

DESIGN

Case-control analysis.

SETTING

Commercial aviation in the United States.

PARTICIPANTS

Aviation employees who were tested for drugs during 1995-2005 under the post-accident testing program (cases, n = 4977) or under the random testing program (controls, n = 1 129 922).

MEASUREMENTS

Point prevalence of drug violations, odds ratio of accident involvement and attributable risk in the population. A drug violation was defined as a confirmed positive test for marijuana (≥50 ng/ml), cocaine (≥300 ng/ml), amphetamines (≥1000 ng/ml), opiates (≥2000 ng/ml) or phencyclidine (≥25 ng/ml).

FINDINGS

The prevalence of drug violations was 0.64% [95% confidence interval (CI): 0.62-0.65%] in random drug tests and 1.82% (95% CI: 1.47-2.24%) in post-accident tests. The odds of accident involvement for employees who tested positive for drugs was almost three times the odds for those who tested negative (odds ratio 2.90, 95% CI: 2.35-3.57), with an estimated attributable risk of 1.2%. Marijuana accounted for 67.3% of the illicit drugs detected. The proportion of illicit drugs represented by amphetamines increased progressively during the study period, from 3.4% in 1995 to 10.3% in 2005 (P < 0.0001).

CONCLUSIONS

Use of illicit drugs by aviation employees is associated with a significantly increased risk of accident involvement. Due to the very low prevalence, drug violations contribute to only a small fraction of aviation accidents.

The first reported generation of human induced pluripotent stem cells (iPS cells) and iPS cell-derived cardiomyocytes in the Netherlands

One of the recent breakthroughs in stem cell research has been the reprogramming of human somatic cells to an embryonic stem cell (ESC)-like state (induced pluripotent stem cells, iPS cells). Similar to ESCs, iPS cells can differentiate into derivatives of the three germ layers, for example cardiomyocytes, pancreatic cells or neurons. This technique offers a new approach to investigating disease pathogenesis and to the development of novel therapies. It may now be possible to generate iPS cells from somatic cells of patients who suffer from vascular genetic diseases, such as hereditary haemorrhagic telangiectasia (HHT). The iPS cells will have a similar genotype to that of the patient and can be differentiated in vitro into the cell type(s) that are affected in the patient. Thus they will serve as excellent models for a better understanding of mechanisms underlying the disease. This, together with the ability to test new drugs, could potentially lead to novel therapeutic concepts in the near future. Here we report the first derivation of three human iPS cell lines from two healthy individuals and one HHT patient in the Netherlands. The iPS cells resembled ESCs in morphology and expressed typical ESC markers. In vitro, iPS cells could be differentiated into cells of the three germ layers, including beating cardiomyocytes and vascular cells. With this technique it will be possible to establish human cardiovascular disease models from patient biopsies provided by the principal hospitals in the Netherlands. (Neth Heart J 2010;18:51-4.).

Bioanalytical procedures for monitoring in utero drug exposure

Drug use by pregnant women has been extensively associated with adverse mental, physical, and psychological outcomes in their exposed children. This manuscript reviews bioanalytical methods for in utero drug exposure monitoring for common drugs of abuse in urine, hair, oral fluid, blood, sweat, meconium, amniotic fluid, umbilical cord tissue, nails, and vernix caseosa; neonatal matrices are particularly emphasized. Advantages and limitations of testing different maternal and neonatal biological specimens including ease and invasiveness of collection, and detection time frames, sensitivities, and specificities are described, and specific references for available analytical methods included. Future research involves identifying metabolites unique to fetal drug metabolism to improve detection rates of in utero drug exposure and determining relationships between the amount, frequency, and timing of drug exposure and drug concentrations in infant biological fluids and tissues. Accurate bioanalytical procedures are vital to defining the scope of and resolving this important public health problem.

Specimen Adulteration and Substitution in Workplace Drug Testing

Throughout the history of workplace drug testing, individuals have attempted to subvert their drug test results to mask their use of illegal drugs. Urine workplace specimens have been subject to tampering, from early attempts involving household chemicals and simple dilution or substitution to current attempts using the multitude of readily available commercial adulteration and substitution products. The manufacturers of such products continue to alter product composition or develop new products to bypass detection procedures and policies implemented by drug testing laboratories and regulatory agencies. This article provides a chronological review of laboratory and regulatory efforts to combat the problem, and presents data from studies on selected commercial adulterant products by the Department of Health and Human Services.

A Decade Revisited - Forensic and Clinical Applications of Hair Testing

Hair testing for metals in clinical and forensic applications began in the 1950s whereas drugs of abuse testing in hair did not begin until the early 1980s. Hair testing has continued to develop as indicated by the publication of more than 300 scientific manuscripts focusing on applications of hair analysis in the past 10 years alone. This review describes many disciplines of hair testing cited in journals and books over the past decade including forensic drug screening, clinical testing, death investigations, and the potential use of newer applications such as reinstatement of driving privileges, detection of doping agents, and testing for drugs used in a criminal act. Each discipline is explained and further details are then illustrated through actual case studies and investigational resultss.

Evaluation of the relative cytotoxic effects of anticancer agents in serum-supplemented versus serum-free media using a tetrazolium colorimetric assay

Most cell culture and in vitro drug sensitivity assays utilize serum-supplemented media (SSM). However, fully defined serum-free media (SFM) offer several advantages and are being used increasingly for initiation and maintenance of cell cultures. Because serum inhibits the in vitro cytotoxicity of certain antineoplastic agents, we investigated the inter-relationships between medium type, cell proliferation and cytotoxic effect. Twenty-four human lung cancer cell lines were tested with nine anticancer agents in both media types. A semi-automated tetrazolium (MTT) colorimetric assay was used for assaying cell survival. Cell lines initiated and maintained in SFM preferentially proliferated in that medium type or proliferated equally well in both media types. In contrast, cell lines established in SSM varied considerably in their medium of preference. There appeared to be a direct correlation or trend between cell proliferative rate and cytotoxicity of all drugs with the possible exceptions of methotrexate and carmustine. In general, the cell lines were more sensitive to anticancer agents when they were exposed in the culture medium in which they preferentially proliferated. Therefore, to determine the influence of culture media on cytotoxicity, we analyzed the data only from lines that replicated equally efficiently in both media. After correction for cell proliferative rate, SSM had a negative effect on the cytotoxic action of some drugs (especially methotrexate, 5-fluorouracil and, to a lesser extent, mitomycin-C). Our results demonstrate that fully defined SFM may be suitable for initiating cell lines and for use in in vitro cytotoxicity assays for selection of individualized therapy or for screening of new anti-neoplastic agents, and thus may increase the number of antineoplastic agents that can be tested satisfactorily.

The Current Legal Status of Drug Testing and Its Implications

Current U.S. law on drug testing is reviewed in this article. The widespread practices of drug abuse and drug testing in the United States are reviewed in the initial section. Legal questions are posed concerning constitutional rights and the rights organized labor has won in the courts during the last century. Federal appellate case law, federal and state statutory law, and military law on drug testing issues are examined in the context of their impact on public, private, criminal justice, and military sectors of American society. Future legal trends on drug testing are predicted in the conclusion.

Important Considerations in the Interpretation of Forensic Urine Drug Test Results

With sound analytical methodology, good laboratory practice, and intact specimen chain-of-custody, test result interpretation is the final element dictating the action to be taken following drug urinalysis. From a technical viewpoint, false test results may be reported as a result of adulteration, including the alteration of metabolic process through the intentional use of foreign material, or the outright addition of adulterants to specimens. Unintended exposure through contact or inhalation may result in the detection of targeted drug analytes at low levels, while the use of certain licit food and medicinal items, such as a salad dressing, a bagel containing poppy seeds, and Tylenol® III, may produce positive results using commonly reporting cutoff levels. For those specimens that test positively, the following factors should be considered when interpreting the meaning of a quantitative result: analyte stability, urine water content, and time lapse between drug exposure and specimen collection.

Solid Phase Extraction of Abused Drugs

The current standard for acceptable practice in forensic urine drug testing, as reflected in both National Institute for Drug Abuse (NIDA) and military guidelines, requires an initial immunoassay followed by gas chromatography/mass spectrometry (GC/MS) confirmation. The GC/MS confirmatory procedures mandate extraction of the drug from the urine matrix, followed in most cases by chemical derivatization, prior to injection into the gas chromatograph. Classically, the extraction step has been accomplished using liquid-liquid techniques, but in recent years, the use of solid phase chromatographic techniques has become increasingly popular. Numerous companies now market solid phase columns that are designed specifically for extraction of drugs, some of them containing as many as three different components for extracting acidic, basic, and neutral drugs. A survey of NIDA laboratories, conducted specifically for this review article, revealed that 40 to 50% of the extraction procedures currently performed involved the use of solid phase cartridges. This article reviews chromatographic separation techniques in general, specific products that are currently available on the market, the performance of those products, and examines the results of the survey of NIDA-certified laboratories.

Specimen Adulteration in Drug Urinalysis

Data from samples adulterated with a variety of substances have been described with respect to their effects on a number of testing methodologies. Several substances have been shown to produce false negative results while others cause positive results in the screening test. Some adulterants cause samples to be negative because the drug, or metabolites, of interest is changed or destroyed while others effect the assay itself. No evidence exists to suggest that an adulterant can cause a false positive result if good forensic procedures are followed including confirmation of initial positive results using a second methodology based on a different chemical principle such as gas chromatography/mass spectrometry.