Long-Term Protective Effect of Tuberculosis Preventive Therapy in a Medium/High Tuberculosis Incidence Setting

BACKGROUND

The duration of the protective effect of tuberculosis preventive therapy (TPT) is controversial. Some studies have found that the protective effect of TPT is lost after cessation of therapy among people with human immunodeficiency virus (HIV) in settings with very high tuberculosis incidence, but others have found long-term protection in low-incidence settings.

METHODS

We estimated the incidence rate (IR) of new tuberculosis disease for up to 12 years after randomization to 4 months of rifampin or 9 months of isoniazid, among 991 Brazilian participants in a TPT trial in the state of Rio de Janeiro, with an incidence of 68.6/100 000 population in 2022. The adjusted hazard ratios (aHRs) of independent variables for incident tuberculosis were calculated.

RESULTS

The overall tuberculosis IR was 1.7 (95% confidence interval [CI], 1.01- 2.7) per 1000 person-years (PY). The tuberculosis IR was higher among those who did not complete TPT than in those who did (2.9 [95% CI, 1.3-5.6] vs 1.1 [.4-2.3] per 1000 PY; IR ratio, 2.7 [1.0-7.2]). The tuberculosis IR was higher within 28 months after randomization (IR, 3.5 [95% CI, 1.6-6.6] vs 1.1 [.5-2.1] per 1000 PY between 28 and 143 months; IR ratio, 3.1 [1.2-8.2]). Treatment noncompletion was the only variable associated with incident tuberculosis (aHR, 3.2 [95% CI, 1.1-9.7]).

CONCLUSIONS

In a mostly HIV-noninfected population, a complete course of TPT conferred long-term protection against tuberculosis.

Association of indicators of extensive disease and rifampin-resistant tuberculosis treatment outcomes: an individual participant data meta-analysis

BACKGROUND

Indicators of extensive disease-acid fast bacilli (AFB) smear positivity and lung cavitation-have been inconsistently associated with clinical rifampin-resistant/multidrug-resistant tuberculosis (RR/MDR-TB) outcomes. We evaluated the association of these indicators with end-of-treatment outcomes.

METHODS

We did an individual participant data meta-analysis of people treated for RR/MDR-TB with longer regimens with documented AFB smear and chest radiography findings. We compared people AFB smear-negative without cavities to people: (1) smear-negative with lung cavities; (2) smear-positive without lung cavities and (3) AFB smear-positive with lung cavities. Using multivariable logistic regression accounting for demographic, treatment and clinical factors, we calculated adjusted ORs (aOR) for any unfavourable outcome (death, lost to follow-up, failure/recurrence), and mortality and treatment failure/recurrence alone.

RESULTS

We included 5596 participants; included participants significantly differed from excluded participants. Overall, 774 (13.8%) were AFB smear-negative without cavities, 647 (11.6%) only had cavities, 1424 (25.4%) were AFB smear-positive alone and 2751 (49.2%) were AFB smear-positive with cavities. The median age was 37 years (IQR: 28-47), 3580 (64%) were male and 686 (12.5%) had HIV. Compared with participants AFB smear-negative without cavities, aOR (95% CI) for any unfavourable outcome was 1.0 (0.8 to 1.4) for participants smear-negative with lung cavities, 1.2 (0.9 to 1.5) if smear-positive without cavities and 1.6 (1.3 to 2.0) if AFB smear-positive with lung cavities. Odds were only significantly increased for mortality (1.5, 95% CI 1.1 to 2.1) and failure/recurrence (2.2, 95% CI 1.5 to 3.3) among participants AFB smear-positive with lung cavities.

CONCLUSION

Only the combination of AFB smear-positivity and lung cavitation was associated with unfavourable outcomes, suggesting they may benefit from stronger regimens.

Residual respiratory disability after successful treatment of pulmonary tuberculosis: a systematic review and meta-analysis

Background

Pulmonary tuberculosis (PTB) can result in long-term health consequences, even after successful treatment. We conducted a systematic review and meta-analysis to estimate the occurrence of respiratory impairment, other disability states, and respiratory complications following successful PTB treatment.

Methods

We identified studies from January 1, 1960, to December 6, 2022, describing populations of all ages that successfully completed treatment for active PTB and had been assessed for at least one of the following outcomes: occurrence of respiratory impairment, other disability states, or respiratory complications following PTB treatment. Studies were excluded if they reported on participants with self-reported TB, extra-pulmonary TB, inactive TB, latent TB, or if participants had been selected on the basis of having more advanced disease. Study characteristics and outcome-related data were abstracted. Meta-analysis was performed using a random effects model. We adapted the Newcastle Ottawa Scale to evaluate the methodological quality of the included studies. Heterogeneity was assessed using the I² statistic and prediction intervals. Publication bias was assessed using Doi plots and LFK indices. This study is registered with PROSPERO (CRD42021276327).

Findings

61 studies with 41,014 participants with PTB were included. In 42 studies reporting post-treatment lung function measurements, 59.1% (I² = 98.3%) of participants with PTB had abnormal spirometry compared to 5.4% (I² = 97.4%) of controls. Specifically, 17.8% (I² = 96.6%) had obstruction, 21.3% (I² = 95.4%) restriction, and 12.7% (I² = 93.2%) a mixed pattern. Among 13 studies with 3179 participants with PTB, 72.6% (I² = 92.8%) of participants with PTB had a Medical Research Council dyspnoea score of 1-2 and 24.7% (I² = 92.2%) a score of 3-5. Mean 6-min walk distance in 13 studies was 440.5 m (I² = 99.0%) in all participants (78.9% predicted, I² = 98.9%) and 403.0 m (I² = 95.1%) among MDR-TB participants in 3 studies (70.5% predicted, I² = 97.6%). Four studies reported data on incidence of lung cancer, with an incidence rate ratio of 4.0 (95% CI 2.1-7.6) and incidence rate difference of 2.7 per 1000 person-years (95% CI 1.2-4.2) when compared to controls. Quality assessment indicated overall low-quality evidence in this field, heterogeneity was high for pooled estimates of nearly all outcomes of interest, and publication bias was considered likely for almost all outcomes.

Interpretation

The occurrence of post-PTB respiratory impairment, other disability states, and respiratory complications is high, adding to the potential benefits of disease prevention, and highlighting the need for optimised management after successful treatment.

Funding

Canadian Institutes of Health Research Foundation Grant.

GeneXpert or chest-X-ray or tuberculin skin testing for household contact assessment (GXT): protocol for a cluster-randomized trial

Background

The World Health Organization recommends tuberculosis (TB) preventive treatment (TPT) for all people living with HIV (PLH) and household contacts (HHC) of index TB patients. Tests for TB infection (TBI) or to rule out TB disease (TBD) are preferred, but if not available, this should not be a barrier if access to these tests is limited for high-risk people, such as PLH and HHC under 5 years old. There is equipoise on the need for these tests in different risk populations, especially HHC aged over 5.

Methods

This superiority cluster-randomized multicenter trial with three arms of equal size compares, in Benin and Brazil, three strategies for HHC investigation aged 0–50: (i) tuberculin skin testing (TST) or interferon gamma release assay (IGRA) for TBI and if positive, chest X-Ray (CXR) to rule out TBD in persons with positive TST or IGRA; (ii) same as (i) but GeneXpert (GX) replaces CXR; and (iii) no TBI testing. CXR for all; if CXR is normal, TPT is recommended. All strategies start with symptom screening. Clusters are defined as HHC members of the same index patients with newly diagnosed pulmonary TBD. The main outcome is the proportion of HHC that are TPT eligible who start TPT within 3 months of the index TB patient starting TBD treatment. Societal costs, incidence of severe adverse events, and prevalence of TBD are among secondary outcomes. Stratified analyses by age (under versus over 5) and by index patient microbiological status will be conducted.

All participants provide signed informed consent. The study was approved by the Research Ethic Board of the Research Institute of the McGill University Health Centre, the Brazilian National Ethical Board CONEP, and the “Comité Local d’Éthique Pour la Recherche Biomédicale (CLERB) de l’Université de Parakou,” Benin. Findings will be submitted for publication in major medical journals and presented in conferences, to WHO and National and municipal TB programs of the involved countries.

Discussion

This randomized trial is meant to provide high-quality evidence to inform WHO recommendations on investigation of household contacts, as currently these are based on very low-quality evidence.

Trial registration

ClinicalTrials.gov NCT04528823.

Implementing the 4R and 9H regimens for TB preventive treatment in Indonesia

BACK GROUND:

The implementation of tuberculosis preventive treatment (TPT) is challenging especially in resource-limited settings. As part of a Phase 3 trial on TPT, we described our experience with the use of rifampicin for 4 months (4R) and isoniazid for 9 months (9H) in Indonesia.

METHODS:

In 2011–2017, children and adults with latent TB infection were randomised to either 4R or 9H and followed until 16 months after randomisation for children and 28 months for adults. The primary outcome was the treatment completion rate. Secondary outcomes were Grade 3–5 adverse events (AEs), active TB occurrence, and health costs.

RESULTS:

A total of 157 children and 860 adults were enrolled. The 4R treatment completion rate was significantly higher than that of 9H (78.7% vs. 65.5%), for a rate difference of 13.2% (95% CI 7.1–19.2). No Grade 3–5 AEs were reported in children; in adults, it was lower in 4R (0.4%) compared to 9H (2.8%). The incidence of active TB was lower with 4R than with 9H (0.09/100 person-year vs. 0.36/100 person-year) (rate difference: −0.36/100 person-year). The total cost per patient was lower for the 4R regimen than for the 9H regimen (USD151.9 vs. USD179.4 in adults and USD152.9 vs. USD206.5 in children)

CONCLUSIONS:

Completion and efficacy rates for 4R were better than for 9H. Compared to 9H, 4R was cheaper in all age groups, safer in adults and equally safe in children. The Indonesian TB program could benefit from these benefits of the 4R regimen.

Scaling up investigation and treatment of household contacts of tuberculosis patients in Brazil: a cost-effectiveness and budget impact analysis

Background

In Brazil, investigation and treatment of tuberculosis infection (TBI) in households contacts (HHC) of TB patients is not a priority. We estimated the cost-effectiveness and budget-impact of scaling-up an enhanced HHC management in Brazil.

Methods

We conceptualized a cascade-of-care that captures how HHC of tuberculosis patients are investigated in Brazil (status quo) and two enhanced strategies for management of HHC focusing on: (1) only tuberculosis disease (TBD) detection and, (2) TBD and TBI detection and treatment. Effectiveness was the number of HHC diagnosed with TBD and completing TBI treatment. Proportions in the cascades-of-care were derived from a meta-analysis. Health-system costs (2019 US$) were based on literature and official data from Brazil. The impact of enhanced strategies was extrapolated using reported data from 2019.

Findings

With the status quo, 0 (95% uncertainty interval: 0-1) HHC are diagnosed with TBD and 2 (0-16) complete TBI treatment. With strategy(1), an additional 15 (3-45) HHC would be diagnosed with TBD at a cost of US$346 each. With strategy(2), 81 (19-226) additional HHC would complete TBI treatment at a cost of US$84 each. A combined strategy, implemented nationally to enhance TBD detection and TBI treatment would result in an additional 9,711 (845-28,693) TBD being detected, and 51,277 (12,028-143,495) more HHC completing TBI treatment each year, utilizing 10.9% and 11.6% of the annual national tuberculosis program budget, respectively.

Interpretation

Enhanced detection and treatment of TBD and TBI among HHC in Brazil can be achieved at a national level using current tools at reasonable cost.

Funding

None.

A simple protocol for tuberculin skin test reading certification

Although tuberculosis preventive therapy is one of the cornerstones for eliminating the disease, many barriers exist in the cascade of care for latent tuberculosis infection, including the need to certify healthcare professionals for reading tuberculin skin tests (TST). This paper proposes and evaluates a simple protocol for TST reading training. Primary care workers from different backgrounds received a 2-hour theoretical course, followed by a practical course on bleb reading. Blebs were obtained by injecting saline into sausages and then in volunteers. A certified trainer then evaluated the effectiveness of this protocol by analyzing the trainees' ability to read TST induration in clinical routine, blinded to each other's readings. Interobserver agreement was analyzed using the Bland-Altman test. The trainees' reading accuracy was calculated using two cut-off points - 5 and 10mm - and the effect of the number of readings was analyzed using a linear mixed model. Eleven healthcare workers read 53 saline blebs and 88 TST indurations, with high agreement for TST reading (0.07mm average bias). Sensitivity was 100% (94.6; 100.0) at 5mm cut-off and 87.3% (75.5; 94.7) at 10mm cut-off. The regression model found no effect of the number of readings [coefficient: -0.007 (-0.055; 0.040)]. A simple training protocol for reading TST with saline blebs simulations in sausages and volunteers was sufficient to achieve accurate TST induration readings, with no effect observed for the number of readings. Training with saline blebs injected into voluntary individuals is safer and easier than the traditional method.

A public health approach to increase treatment of latent TB among household contacts in Brazil

SETTING: Two consecutive trials were conducted to evaluate the effectiveness of a public health approach to identify and correct problems in the care cascade for household contacts (HHCs) of TB patients in three Brazilian high TB incidence cities.METHODS: In the first trial, 12 clinics underwent standardised evaluation using questionnaires administered to TB patients, HHCs and healthcare workers, and analysis of the cascade of latent TB care among HHCs. Six clinics were then randomised to receive interventions to strengthen management of latent TB infection (LTBI), including in-service training provided by nurses, work process organisation and additional clinic-specific solutions. In the second trial, a similar but streamlined evaluation was conducted in two clinics, who then received initial and subsequent intensive in-service training provided by a physician.RESULTS: In the evaluation phase of both trials, many HHCs were identified, but few started LTBI treatment. After the intervention, the number of HHCs initiating treatment per 100 active TB patients increased by 10 (95%CI - 11 to 30) in the first trial, and by 44 (95%CI 26 to 61) in the second trial.DISCUSSION: A public health approach with standardised evaluation, local decisions for improvements, followed by intensive initial and in-service training appears promising for improved LTBI management.

The Sensitivity and Costs of Testing for SARS-CoV-2 Infection With Saliva Versus Nasopharyngeal Swabs : A Systematic Review and Meta-analysis

BACKGROUND

Nasopharyngeal swabs are the primary sampling method used for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but they require a trained health care professional and extensive personal protective equipment.

PURPOSE

To determine the difference in sensitivity for SARS-CoV-2 detection between nasopharyngeal swabs and saliva and estimate the incremental cost per additional SARS-CoV-2 infection detected with nasopharyngeal swabs.

DATA SOURCES

Embase, Medline, medRxiv, and bioRxiv were searched from 1 January to 1 November 2020. Cost inputs were from nationally representative sources in Canada and were converted to 2020 U.S. dollars.

STUDY SELECTION

Studies including at least 5 paired nasopharyngeal swab and saliva samples and reporting diagnostic accuracy for SARS-CoV-2 detection.

DATA EXTRACTION

Data were independently extracted using standardized forms, and study quality was assessed using QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2).

DATA SYNTHESIS

Thirty-seven studies with 7332 paired samples were included. Against a reference standard of a positive result on either sample, the sensitivity of saliva was 3.4 percentage points lower (95% CI, 9.9 percentage points lower to 3.1 percentage points higher) than that of nasopharyngeal swabs. Among persons with previously confirmed SARS-CoV-2 infection, saliva's sensitivity was 1.5 percentage points higher (CI, 7.3 percentage points lower to 10.3 percentage points higher) than that of nasopharyngeal swabs. Among persons without a previous SARS-CoV-2 diagnosis, saliva was 7.9 percentage points less (CI, 14.7 percentage points less to 0.8 percentage point more) sensitive. In this subgroup, if testing 100 000 persons with a SARS-CoV-2 prevalence of 1%, nasopharyngeal swabs would detect 79 more (95% uncertainty interval, 5 fewer to 166 more) persons with SARS-CoV-2 than saliva, but with an incremental cost per additional infection detected of $8093.

LIMITATION

The reference standard was imperfect, and saliva collection procedures varied.

CONCLUSION

Saliva sampling seems to be a similarly sensitive and less costly alternative that could replace nasopharyngeal swabs for collection of clinical samples for SARS-CoV-2 testing.

PRIMARY FUNDING SOURCE

McGill Interdisciplinary Initiative in Infection and Immunity. (PROSPERO: CRD42020203415).

Effects of programmatic interventions to improve the management of latent tuberculosis: a follow up study up to five months after implementation

Background

Less than 19% of those needing tuberculosis (TB) preventive treatment complete it, due to losses in several steps of the cascade of care for latent TB infection. A cluster randomized trial of a programmatic public health intervention to improve management of latent TB infection in household contacts was conducted in Rio de Janeiro. Interventions included contact registry, initial and in-service training, and a TB booklet. We conducted a follow-up study starting one month after the conclusion of this trial, to measure the effect of interventions implemented, and to identify remaining barriers and facilitators to latent TB infection treatment, from different perspectives.

Methods

In two health clinics in Rio de Janeiro that received the interventions in the trial, data for the latent TB infection cascade of care for household contacts was collected over a five-month period. The number of household contacts initiating treatment per 100 index-TB patients was compared with the cascade of care data obtained before and during the intervention trial. Semi-structured open-ended questionnaires were administered to healthcare workers, household contacts and index-TB patients regarding knowledge and perceptions about TB and study interventions.

Results

In this follow-up study, 184 household contacts per 100 index-TB patients were identified. When compared to the intervention period, there were 65 fewer household contacts per 100 index-TB patients, (95% CI -115, − 15) but the number starting latent TB infection treatment was sustained (difference -2, 95% CI -8,5). A total of 31 index-TB patients, 22 household contacts and 19 health care workers were interviewed. Among index-TB patients, 61% said all their household contacts had been tested for latent TB infection. All health care workers said it was very important to test household contacts, and 95% mentioned that possessing correct knowledge on the benefits of latent TB infection treatment was the main facilitator to enable them to recommend this treatment.

Conclusion

In this follow-up study, we observed a sustained effect of interventions to strengthen the latent TB infection cascade of care on increasing the number of household contacts starting latent TB infection treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10195-z.

Active testing of groups at increased risk of acquiring SARS-CoV-2 in Canada: costs and human resource needs

BACKGROUND

Testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is largely passive, which impedes epidemic control. We defined active testing strategies for SARS-CoV-2 using reverse transcription polymerase chain reaction (RT-PCR) for groups at increased risk of acquiring SARS-CoV-2 in all Canadian provinces.

METHODS

We identified 5 groups who should be prioritized for active RT-PCR testing: contacts of people who are positive for SARS-CoV-2, and 4 at-risk populations - hospital employees, community health care workers and people in long-term care facilities, essential business employees, and schoolchildren and staff. We estimated costs, human resources and laboratory capacity required to test people in each group or to perform surveillance testing in random samples.

RESULTS

During July 8-17, 2020, across all provinces in Canada, an average of 41 751 RT-PCR tests were performed daily; we estimated this required 5122 personnel and cost $2.4 million per day ($67.8 million per month). Systematic contact tracing and testing would increase personnel needs 1.2-fold and monthly costs to $78.9 million. Conducted over a month, testing all hospital employees would require 1823 additional personnel, costing $29.0 million; testing all community health care workers and persons in long-term care facilities would require 11 074 additional personnel and cost $124.8 million; and testing all essential employees would cost $321.7 million, requiring 25 965 added personnel. Testing the larger population within schools over 6 weeks would require 46 368 added personnel and cost $816.0 million. Interventions addressing inefficiencies, including saliva-based sampling and pooling samples, could reduce costs by 40% and personnel by 20%. Surveillance testing in population samples other than contacts would cost 5% of the cost of a universal approach to testing at-risk populations.

INTERPRETATION

Active testing of groups at increased risk of acquiring SARS-CoV-2 appears feasible and would support the safe reopening of the economy and schools more broadly. This strategy also appears affordable compared with the $169.2 billion committed by the federal government as a response to the pandemic as of June 2020.

Health System Costs of Treating Latent Tuberculosis Infection With Four Months of Rifampin Versus Nine Months of Isoniazid in Different Settings

BACKGROUND

Four months of rifampin treatment for latent tuberculosis infection is safer, has superior treatment completion rates, and is as effective as 9 months of isoniazid. However, daily medication costs are higher for a 4-month rifampin regimen than a 9-month isoniazid regimen.

OBJECTIVE

To compare health care use and associated costs of 4 months of rifampin and 9 months of isoniazid.

DESIGN

Health system cost comparison using all health care activities recorded during 2 randomized clinical trials. (ClinicalTrials.gov: NCT00931736 and NCT00170209).

SETTING

High-income countries (Australia, Canada, Saudi Arabia, and South Korea), middle-income countries (Brazil and Indonesia), and African countries (Benin, Ghana, and Guinea).

PARTICIPANTS

Adults and children with clinical or epidemiologic factors associated with increased risk for developing tuberculosis that warranted treatment for latent tuberculosis infection.

MEASUREMENTS

Health system costs per participant.

RESULTS

A total of 6012 adults and 829 children were included. In both adults and children, greater health system use and higher costs were observed with 9 months of isoniazid than with 4 months of rifampin. In adults, the ratios of costs of 4 months of rifampin versus 9 months of isoniazid were 0.76 (95% CI, 0.70 to 0.82) in high-income countries, 0.90 (CI, 0.85 to 0.96) in middle-income countries, and 0.80 (CI, 0.78 to 0.81) in African countries. Similar findings were observed in the pediatric population.

LIMITATION

Costs may have been overestimated because the trial protocol required a minimum number of follow-up visits, although fewer than recommended by many authoritative guidelines.

CONCLUSION

A 4-month rifampin regimen was safer and less expensive than 9 months of isoniazid in all settings. This regimen could be adopted by tuberculosis programs in many countries as first-line therapy for latent tuberculosis infection.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research.

Diagnostic accuracy of serological tests for covid-19: systematic review and meta-analysis

OBJECTIVE

To determine the diagnostic accuracy of serological tests for coronavirus disease-2019 (covid-19).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, bioRxiv, and medRxiv from 1 January to 30 April 2020, using subject headings or subheadings combined with text words for the concepts of covid-19 and serological tests for covid-19.

ELIGIBILITY CRITERIA AND DATA ANALYSIS

Eligible studies measured sensitivity or specificity, or both of a covid-19 serological test compared with a reference standard of viral culture or reverse transcriptase polymerase chain reaction. Studies were excluded with fewer than five participants or samples. Risk of bias was assessed using quality assessment of diagnostic accuracy studies 2 (QUADAS-2). Pooled sensitivity and specificity were estimated using random effects bivariate meta-analyses.

MAIN OUTCOME MEASURES

The primary outcome was overall sensitivity and specificity, stratified by method of serological testing (enzyme linked immunosorbent assays (ELISAs), lateral flow immunoassays (LFIAs), or chemiluminescent immunoassays (CLIAs)) and immunoglobulin class (IgG, IgM, or both). Secondary outcomes were stratum specific sensitivity and specificity within subgroups defined by study or participant characteristics, including time since symptom onset.

RESULTS

5016 references were identified and 40 studies included. 49 risk of bias assessments were carried out (one for each population and method evaluated). High risk of patient selection bias was found in 98% (48/49) of assessments and high or unclear risk of bias from performance or interpretation of the serological test in 73% (36/49). Only 10% (4/40) of studies included outpatients. Only two studies evaluated tests at the point of care. For each method of testing, pooled sensitivity and specificity were not associated with the immunoglobulin class measured. The pooled sensitivity of ELISAs measuring IgG or IgM was 84.3% (95% confidence interval 75.6% to 90.9%), of LFIAs was 66.0% (49.3% to 79.3%), and of CLIAs was 97.8% (46.2% to 100%). In all analyses, pooled sensitivity was lower for LFIAs, the potential point-of-care method. Pooled specificities ranged from 96.6% to 99.7%. Of the samples used for estimating specificity, 83% (10 465/12 547) were from populations tested before the epidemic or not suspected of having covid-19. Among LFIAs, pooled sensitivity of commercial kits (65.0%, 49.0% to 78.2%) was lower than that of non-commercial tests (88.2%, 83.6% to 91.3%). Heterogeneity was seen in all analyses. Sensitivity was higher at least three weeks after symptom onset (ranging from 69.9% to 98.9%) compared with within the first week (from 13.4% to 50.3%).

CONCLUSION

Higher quality clinical studies assessing the diagnostic accuracy of serological tests for covid-19 are urgently needed. Currently, available evidence does not support the continued use of existing point-of-care serological tests.

STUDY REGISTRATION

PROSPERO CRD42020179452.

Active and latent tuberculosis in refugees and asylum seekers: a systematic review and meta-analysis

Background

In 2018, there were 70.8 million refugees, asylum seekers and persons displaced by wars and conflicts worldwide. Many of these individuals face a high risk for tuberculosis in their country of origin, which may be accentuated by adverse conditions endured during their journey. We summarised the prevalence of active and latent tuberculosis infection in refugees and asylum seekers through a systematic literature review and meta-analyses by country of origin and host continent.

Methods

Articles published in Medline, EMBASE, Web of Science and LILACS from January 2000 to August 2017 were searched for, without language restriction. Two independent authors performed the study selection, data extraction and quality assessment. Random effect models were used to estimate average measures of active and latent tuberculosis prevalence. Sub-group meta-analyses were performed according to country of origin and host continent.

Results

Sixty-seven out of 767 identified articles were included, of which 16 entered the meta-analyses. Average prevalence of active and latent tuberculosis was 1331 per 100 thousand inhabitants [95% confidence interval (CI) = 542–2384] and 37% (95% CI = 23–52%), respectively, both with high level of heterogeneity (variation in estimative attributable to heterogeneity [I²] = 98.2 and 99.8%). Prevalence varied more according to countries of origin than host continent. Ninety-one per cent of studies reported routine screening of recently arrived immigrants in the host country; two-thirds confirmed tuberculosis bacteriologically. Many studies failed to provide relevant information.

Conclusion

Tuberculosis is a major health problem among refugees and asylum seekers and should be given special attention in any host continent. To protect this vulnerable population, ensuring access to healthcare for early detection for prevention and treatment of the disease is essential.

The interplay between autophagy and apoptosis mediates toxicity triggered by synthetic cathinones in human kidney cells

Synthetic cathinones abuse remains a serious public health problem. Kidney injury has been reported in intoxications associated with synthetic cathinones, but the molecular mechanisms involved have not been explored yet. In this study, the potential in vitro nephrotoxic effects of four commonly abused cathinone derivatives, namely pentedrone, 3,4-dimethylmethcatinone (3,4-DMMC), methylone and 3,4-methylenedioxypyrovalerone (MDPV), were assessed in the human kidney HK-2 cell line. All four derivatives elicited cell death in a concentration- and time-dependent manner, in the following order of potency: 3,4-DMMC >> MDPV > methylone ≈ pentedrone. 3,4-DMMC and methylone were selected to further elucidate the mechanisms behind synthetic cathinones-induced cell death. Both drugs elicited apoptotic cell death and prompted the formation of acidic vesicular organelles and autophagosomes in HK-2 cells. Moreover, the autophagy inhibitor 3-methyladenine significantly potentiated cell death, indicating that autophagy may serve as a cell survival mechanism that protects renal cells against synthetic cathinones toxicity. Both drugs triggered a rise in reactive oxygen and nitrogen species formation, which was completely prevented by antioxidant treatment with N‑acetyl‑L‑cysteine or ascorbic acid. Importantly, these antioxidant agents significantly aggravated renal cell death induced by cathinone derivatives, most likely due to their autophagy-blocking properties. Taken together, our results support an intricate control of cell survival/death modulated by oxidative stress, apoptosis and autophagy in synthetic cathinones-induced renal injury.

Prevalence of sexual violence among refugees: a systematic review

OBJECTIVE

To synthesize data about the prevalence of sexual violence (SV) among refugees around the world.

METHODS

A systematic review was conducted from the search in seven bibliographic databases. Studies on the prevalence of SV among refugees and asylum seekers of any country, sex or age, whether in English, French, Spanish and Portuguese, were eligible.

RESULTS

Of the 2,906 titles found, 60 articles were selected. The reported prevalence of SV was largely variable (0% to 99.8%). Reports of SV were collected in all continents, with 42% of the articles mentioning it in refugees from Africa (prevalence from 1.3% to 100%). The rape was the most reported SV in 65% of the studies (prevalence from 0% to 90.9%). The main victims were women in 89% of the studies, all the way, especially when still in the countries of origin. The SV was perpetrated particularly by intimate partners, but also by agents of supposed protection. Few studies have reported SV in men and children; the prevalence reached up to 39.3% and 90.9%, respectively. Approximately one-third of the studies (32%) were carried out in refugee camps and more than half (52%) in health services using mental health assessment tools. No study has addressed the most recent migratory crisis. Meta-analysis was not performed due to the methodological heterogeneity of the studies.

CONCLUSIONS

SV is a prevalent problem affecting refugees of both sexes, of all ages, throughout the migratory journey, particularly those from Africa. Protection measures are urgently needed, and further studies, with more appropriate tools, may better measure the current magnitude of the problem.

Treatment outcomes of MDR-tuberculosis patients in Brazil: a retrospective cohort analysis

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) is a threat for the global TB epidemic control. Despite existing evidence that individualized treatment of MDR-TB is superior to standardized regimens, the latter are recommended in Brazil, mainly because drug-susceptibility tests (DST) are often restricted to first-line drugs in public laboratories. We compared treatment outcomes of MDR-TB patients using standardized versus individualized regimens in Brazil, a high TB-burden, low resistance setting.

METHODS

The 2007-2013 cohort of the national electronic database (SITE-TB), which records all special treatments including drug-resistance, was analysed. Patients classified as MDR-TB in SITE-TB were eligible. Treatment outcomes were classified as successful (cure/treatment completed) or unsuccessful (failure/relapse/death/loss to follow-up). The odds for successful treatment according to type of regimen were controlled for demographic and clinical variables.

RESULTS

Out of 4029 registered patients, we included 1972 recorded from 2010 to 2012, who had more complete outcome data. The overall success proportion was 60%. Success was more likely in non-HIV patients, sputum-negative at baseline, with unilateral disease and without prior DR-TB. Adjusted for these variables, those receiving standardized regimens had 2.7-fold odds of success compared to those receiving individualized treatments when failure/relapse were considered, and 1.4-fold odds of success when death was included as an unsuccessful outcome. When loss to follow-up was added, no difference between types of treatment was observed. Patients who used levofloxacin instead of ofloxacin had 1.5-fold odds of success.

CONCLUSION

In this large cohort of MDR-TB patients with a low proportion of successful outcomes, standardized regimens had superior efficacy than individualized regimens, when adjusted for relevant variables. In addition to the limitations of any retrospective observational study, database quality hampered the analyses. Also, decision on the use of standard or individualized regimens was possibly not random, and may have introduced bias. Efforts were made to reduce classification bias and confounding. Until higher-quality evidence is produced, and DST becomes widely available in the country, our findings support the Brazilian recommendation for the use of standardized instead of individualized regimens for MDR-TB, preferably containing levofloxacin. Better quality surveillance data and DST availability across the country are necessary to improve MDR-TB control in Brazil.

The impact of the Brazilian family health strategy on selected primary care sensitive conditions: A systematic review

Background

Brazil has the largest public health-system in the world, with 120 million people covered by its free primary care services. The Family Health Strategy (FHS) is the main primary care model, but there is no consensus on its impact on health outcomes. We systematically reviewed published evidence regarding the impact of the Brazilian FHS on selective primary care sensitive conditions (PCSC).

Methods

We searched Medline, Web of Science and Lilacs in May 2016 using key words in Portuguese and English, without language restriction. We included studies if intervention was the FHS; comparison was either different levels of FHS coverage or other primary health care service models; outcomes were the selected PCSC; and results were adjusted for relevant sanitary and socioeconomic variables, including the national conditional cash transfer program (Bolsa Familia). Due to differences in methods and outcomes reported, pooling of results was not possible.

Results

Of 1831 records found, 31 met our inclusion criteria. Of these, 25 were ecological studies. Twenty-one employed longitudinal quasi-experimental methods, 27 compared different levels the FHS coverage, whilst four compared the FHS versus other models of primary care. Fourteen studies found an association between higher FHS coverage and lower post-neonatal and child mortality. When the effect of Bolsa Familia was accounted for, the effect of the FHS on child mortality was greater. In 13 studies about hospitalizations due to PCSC, no clear pattern of association was found. In four studies, there was no effect on child and elderly vaccination or low-birth weight. No included studies addressed breast-feeding, dengue, HIV/AIDS and other neglected infectious diseases.

Conclusions

Among these ecological studies with limited quality evidence, increasing coverage by the FHS was consistently associated with improvements in child mortality. Scarce evidence on other health outcomes, hospitalization and synergies with cash transfer was found.

An updated systematic review and meta-analysis for treatment of multidrug-resistant tuberculosis

This systematic review aimed to update the current evidence for multidrug-resistant tuberculosis (MDR-TB) treatment.We searched for studies that reported treatment information and clinical characteristics for at least 25 patients with microbiologically confirmed pulmonary MDR-TB and either end of treatment outcomes, 6-month culture conversion or severe adverse events (SAEs). We assessed the association of these outcomes with patients' characteristics or treatment parameters. We identified 74 studies, including 17 494 participants.The pooled treatment success was 26% in extensively drug-resistant TB (XDR-TB) patients and 60% in MDR-TB patients. Treatment parameters such as number or duration and individual drugs were not associated with improved 6-month sputum culture conversion or end of treatment outcomes. However, MDR-TB patients that received individualised regimens had higher success than patients who received standardised regimens (64% versus 52%; p<0.0.01). When reports from 20 cohorts were pooled, proportions of SAE ranged from 0.5% attributed to ethambutol to 12.2% attributed to para-aminosalicylic acid. The lack of significant associations of treatment outcomes with specific drugs or regimens may reflect the limitations of pooling the data rather than a true lack of differences in efficacy of regimens or individual drugs.This analysis highlights the need for stronger evidence for treatment of MDR-TB from better-designed and reported studies.

Toxicity of the amphetamine metabolites 4-hydroxyamphetamine and 4-hydroxynorephedrine in human dopaminergic differentiated SH-SY5Y cells

Amphetamine (AMPH) is a psychostimulant used worldwide by millions of patients in the clinical treatment of attention deficit hyperactivity disorder, narcolepsy or even obesity, and is also a drug of abuse. 4-Hydroxynorephedrine (4-OHNE) and 4-hydroxyamphetamine (4-OHAMPH) are two major metabolites known to persist in the brain longer than AMPH. The contribution of AMPH metabolites for its neurotoxicity is undetermined. We evaluated the toxicity of AMPH and its metabolites 4-OHNE and 4-OHAMPH, obtained by chemical synthesis, in human dopaminergic differentiated SH-SY5Y neurons. Cells were exposed to AMPH (concentration range 0-5mM) or 4-OHAMPH or 4-OHNE (concentration range 0-10mM) for 24 or 48h, and the viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) leakage assays. Results showed that for both AMPH and the metabolites a concentration-dependent toxicity was observed. The toxic concentration 50% (TC₅₀) for AMPH and 4-OHNE following 24h exposure was circa 3.5mM and 8mM, respectively. For 4-OHAMPH the TC₅₀ was not reached in the tested concentration range. N-acetyl cysteine, cycloheximide, l-carnitine, and methylphenidate were able to reduce cell death induced by AMPH TC₅₀. Acridine orange/ethidium bromide staining showed evident signs of late apoptotic cells and necrotic cells following 24h exposure to AMPH 3.50mM. The 4-OHAMPH metabolite at 8.00mM originated few late apoptotic cells, whereas 4-OHNE at 8.00mM resulted in late apoptotic cells and necrotic cells, in a scenario similar to AMPH. In conclusion, the AMPH metabolite 4-OHNE is more toxic than 4-OHAMPH, nonetheless both are less toxic than the parent compound in vitro. The most toxic metabolite 4-OHNE has longer permanence in the brain, rendering likely its contribution for AMPH neurotoxicity.

Cost and cost-effectiveness of tuberculosis treatment shortening: a model-based analysis

Background

Despite improvements in treatment success rates for tuberculosis (TB), current six-month regimen duration remains a challenge for many National TB Programmes, health systems, and patients. There is increasing investment in the development of shortened regimens with a number of candidates in phase 3 trials.

Methods

We developed an individual-based decision analytic model to assess the cost-effectiveness of a hypothetical four-month regimen for first-line treatment of TB, assuming non-inferiority to current regimens of six-month duration. The model was populated using extensive, empirically-collected data to estimate the economic impact on both health systems and patients of regimen shortening for first-line TB treatment in South Africa, Brazil, Bangladesh, and Tanzania. We explicitly considered ‘real world’ constraints such as sub-optimal guideline adherence.

Results

From a societal perspective, a shortened regimen, priced at USD1 per day, could be a cost-saving option in South Africa, Brazil, and Tanzania, but would not be cost-effective in Bangladesh when compared to one gross domestic product (GDP) per capita. Incorporating ‘real world’ constraints reduces cost-effectiveness. Patient-incurred costs could be reduced in all settings. From a health service perspective, increased drug costs need to be balanced against decreased delivery costs. The new regimen would remain a cost-effective option, when compared to each countries’ GDP per capita, even if new drugs cost up to USD7.5 and USD53.8 per day in South Africa and Brazil; this threshold was above USD1 in Tanzania and under USD1 in Bangladesh.

Conclusion

Reducing the duration of first-line TB treatment has the potential for substantial economic gains from a patient perspective. The potential economic gains for health services may also be important, but will be context-specific and dependent on the appropriate pricing of any new regimen.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2064-3) contains supplementary material, which is available to authorized users.

Naphthoquinoxaline metabolite of mitoxantrone is less cardiotoxic than the parent compound and it can be a more cardiosafe drug in anticancer therapy

Mitoxantrone (MTX) is an antineoplastic agent used to treat several types of cancers and on multiple sclerosis, which shows a high incidence of cardiotoxicity. Still, the underlying mechanisms of MTX cardiotoxicity are poorly understood and the potential toxicity of its metabolites scarcely investigated. Therefore, this work aimed to synthesize the MTX-naphthoquinoxaline metabolite (NAPHT) and to compare its cytotoxicity to the parent compound in 7-day differentiated H9c2 cells using pharmacological relevant concentrations (0.01-5 µM). MTX was more toxic in equivalent concentrations in all cytotoxicity tests performed [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide reduction, neutral red uptake, and lactate dehydrogenase release assays] and times tested (24 and 48 h). Both MTX and NAPHT significantly decreased mitochondrial membrane potential in 7-day differentiated H9c2 cells after a 12-h incubation. However, energetic pathways were affected in a different manner after MTX or NAPHT incubation. ATP increased and lactate levels decreased after a 24-h incubation with MTX, whereas for the same incubation time and concentrations, NAPHT did not cause any significant effect. The increased activity of ATP synthase seems responsible for MTX-induced increases in ATP levels, as oligomycin (an inhibitor of ATP synthase) abrogated this effect on 5 µM MTX-incubated cells. 3-Methyladenine (an autophagy inhibitor) was the only molecule to give a partial protection against the cytotoxicity produced by MTX or NAPHT. To the best of our knowledge, this was the first broad study on NAPHT cardiotoxicity, and it revealed that the parent drug, MTX, caused a higher disruption in the energetic pathways in a cardiac model in vitro, whereas autophagy is involved in the toxicity of both compounds. In conclusion, NAPHT is claimed to largely contribute to MTX-anticancer properties; therefore, this metabolite should be regarded as a good option for a safer anticancer therapy since it is less cardiotoxic than MTX.

Shortened first-line TB treatment in Brazil: potential cost savings for patients and health services

BACKGROUND

Shortened treatment regimens for tuberculosis are under development to improve treatment outcomes and reduce costs. We estimated potential savings from a societal perspective in Brazil following the introduction of a hypothetical four-month regimen for tuberculosis treatment.

METHODS

Data were gathered in ten randomly selected health facilities in Rio de Janeiro. Health service costs were estimated using an ingredient approach. Patient costs were estimated from a questionnaire administered to 126 patients. Costs per visits and per case treated were analysed according to the type of therapy: self-administered treatment (SAT), community- and facility-directly observed treatment (community-DOT, facility-DOT).

RESULTS

During the last 2 months of treatment, the largest savings could be expected for community-DOT; on average USD 17,351-18,203 and USD 43,660-45,856 (bottom-up and top-down estimates) per clinic. Savings to patients could also be expected as the median (interquartile range) patient-related costs during the two last months were USD 108 (13-291), USD 93 (36-239) and USD 11 (7-126), respectively for SAT, facility-DOT and community-DOT.

CONCLUSION

Introducing a four-month regimen may result in significant cost savings for both the health service and patients, especially the poorest. In particular, a community-DOT strategy, including treatment at home, could maximise health services savings while limiting patient costs. Our cost estimates are likely to be conservative because a 4-month regimen could hypothetically increase the proportion of patients cured by reducing the number of patients defaulting and we did not include the possible cost benefits from the subsequent prevention of costs due to downstream transmission averted and rapid clinical improvement with less side effects in the last two months.

In vitro neurotoxicity evaluation of piperazine designer drugs in differentiated human neuroblastoma SH-SY5Y cells

Abuse of synthetic drugs is widespread worldwide. Studies indicate that piperazine designer drugs act as substrates at dopaminergic and serotonergic receptors and/or transporters in the brain. This work aimed to investigate the cytotoxicity of N-benzylpiperazine, 1-(3-trifluoromethylphenyl)piperazine, 1-(4-methoxyphenyl)piperazine and 1-(3,4-methylenedioxybenzyl)piperazine in the differentiated human neuroblastoma SH-SY5Y cell line. Cytotoxicity was evaluated after 24 h incubations through the MTT reduction and neutral red uptake assays. Oxidative stress (reactive oxygen and nitrogen species production and glutathione content) and energetic (ATP content) parameters, as well as intracellular Ca(2+), mitochondrial membrane potential, DNA damage (comet assay) and cell death mode were also evaluated. Complete cytotoxicity curves were obtained after 24 h incubations with each drug. A significant decrease in intracellular total glutathione content was noted for all the tested drugs. All drugs caused a significant increase of intracellular free Ca(2+) levels, accompanied by mitochondrial hyperpolarization. However, ATP levels remained unchanged. The investigation of cell death mode revealed a predominance of early apoptotic cells. No genotoxicity was found in the comet assay. Among the tested drugs, 1-(3-trifluoromethylphenyl)piperazine was the most cytotoxic. Overall, piperazine designer drugs are potentially neurotoxic, supporting concerns on risks associated with the abuse of these drugs.

Metabolomics analysis for biomarker discovery: advances and challenges

Over the last decades there has been a change in biomedical research with the search for single genes, transcripts, proteins, or metabolites being substituted by the coverage of the entire genome, transcriptome, proteome, and metabolome with the "omics" approaches. The emergence of metabolomics, defined as the comprehensive analysis of all metabolites in a system, is still recent compared to other "omics" fields, but its particular features and the improvement of both analytical techniques and pattern recognition methods has contributed greatly to its increasingly use. The feasibility of metabolomics for biomarker discovery is supported by the assumption that metabolites are important players in biological systems and that diseases cause disruption of biochemical pathways, which are not new concepts. In fact, metabolomics, meaning the parallel assessment of multiple metabolites, has been shown to have benefits in various clinical areas. Compared to classical diagnostic approaches and conventional clinical biomarkers, metabolomics offers potential advantages in sensitivity and specificity. Despite its potential, metabolomics still retains several intrinsic limitations which have a great impact on its widespread implementation - these limitations in biological and experimental measurements. This review will provide an insight to the characteristics, strengths, limitations, and recent advances in metabolomics, always keeping in mind its potential application in clinical/ health areas as a biomarker discovery tool.

Piperazine compounds as drugs of abuse

Synthetic drugs are among the most commonly abused drugs in the world. This abuse is widespread among young people, especially in the dance club and rave scenes. Over the last several years, piperazine derived drugs have appeared, mainly available via the internet, and sold as ecstasy pills or under the names of "Frenzy", "Bliss", "Charge", "Herbal ecstasy", "A2", "Legal X" and "Legal E". Although in the market piperazine designer drugs have the reputation of being safe, several experimental and epidemiological studies indicate risks for humans. Piperazine designer drugs can be divided into two classes, the benzylpiperazines such as N-benzylpiperazine (BZP) and its methylenedioxy analogue 1-(3,4-methylenedioxybenzyl)piperazine (MDBP), and the phenylpiperazines such as 1-(3-chlorophenyl)piperazine (mCPP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), and 1-(4-methoxyphenyl)piperazine (MeOPP). Toxicokinetic properties, including metabolic pathways, actions and effects in animals and humans, with some hypothesis of mechanism of action, and analytical approaches for the identification of these drugs are summarized in this review.

Contribution of catecholamine reactive intermediates and oxidative stress to the pathologic features of heart diseases

Pathologic heart conditions, particularly heart failure (HF) and ischemia-reperfusion (I/R) injury, are characterized by sustained elevation of plasma and interstitial catecholamine levels, as well as by the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Despite the continuous and extensive research on catecholamines since the early years of the XX(th) century, the mechanisms underlying catecholamine-induced cardiotoxicity are still not fully elucidated. The role of catecholamines in HF, stress cardiomyopathy, I/R injury, ageing, stress, and pheochromocytoma will be thoroughly discussed. Furthermore and although the noxious effects resulting from catecholamine excess have traditionally been linked to adrenoceptors, in fact, several evidences indicate that oxidative stress and the oxidation of catecholamines can have important roles in catecholamine-induced cardiotoxicity. Accordingly, the reactive intermediates formed during catecholamine oxidation have been associated with cardiac toxicity, both in in vitro and in vivo studies. An insight into the influence of ROS, RNS, and catecholamine oxidation products on several heart diseases and their clinical course will be provided. In addition, the source and type of oxidant species formed in some heart pathologies will be referred. In this review a special focus will be given to the research of cardiac pathologies where catecholamines and oxidative stress are involved. An integrated vision of these matters is required and will be provided along this review, namely how the concomitant surge of catecholamines and ROS occurs and how they can be interconnected. The concomitant presence of these factors can elicit peculiar and not fully characterized responses on the heart. We will approach the existing data with new perspectives as they can help explaining several controversial results regarding cardiovascular diseases and the redox ability of catecholamines.

Water extracts of Brassica oleracea var. costata potentiate paraquat toxicity to rat hepatocytes in vitro

Tronchuda cabbage extracts have been proven to have antioxidant potential against various oxidative species in cell free systems, though its antioxidant potential in cellular models remained to be demonstrated. In the present study, we used primary cultures of rat hepatocytes for the cellular assay system and paraquat PQ exposure as a pro-oxidant model agent, to test whether tronchuda cabbage hydrolysed water extracts provide protective or aggravating effects towards PQ-induced oxidative stress and cell death. For this purpose cellular parameters related to oxidative stress were measured, namely the generation of superoxide anion, glutathione oxidation, lipid peroxidation, intracellular ATP levels, activation of nuclear factor-kappaB (NF-kappaB), activity of antioxidant enzymes, and cell death. The obtained results demonstrated that the studied hydrolysed water extracts of tronchuda cabbage, especially rich in kaempferol (84%) and other polyphenols, namely hydroxycinnamic acids and traces of quercetin, can potentiate the toxicity of PQ in primary cultures of rat hepatocytes. These results highlight that prospective antioxidant effects of plant extracts, observed in vitro, using non-cellular systems, are not always confirmed in cellular models, in which the concentrations required to scavenge pro-oxidant species may be highly detrimental to the cells.

An effective antidote for paraquat poisonings: the treatment with lysine acetylsalicylate

Sodium salicylate (NaSAL) has been shown to have a multifactorial protection mechanism against paraquat (PQ)-induced toxicity, due to its ability to modulate inflammatory signalling systems, to prevent oxidative stress and to its capacity to chelate PQ. Considering that currently there is no pharmaceutical formulation available for parenteral administration of NaSAL, the aim of the present study was to evaluate the antidotal feasibility of a salicylate prodrug, lysine acetylsalicylate (LAS), accessible for parenteral administrations. PQ was administered to Wistar rats by gavage (125mg/kg of PQ ion) and the treatment was performed intraperitoneally with different doses (100, 200 and 400mg/kg of body weight) of LAS. Survival rate was followed during 30 days and living animals at this endpoint were sacrificed for lung, kidney, liver, jejune and heart histological analysis. It was shown, that the salicylate prodrug, LAS, available in a large number of hospitals, is also effective in the treatment of PQ intoxications. From all tested LAS doses, 200mg/kg assured animal's full survival. Comparatively to 60% of mortality observed in PQ only exposed animals, the lethality was higher (80%) in the group that received 400mg/kg of LAS 2h after PQ administration. The dose of 100mg/kg of LAS showed only a modest protection (60% of survival). Collagen deposition was observed by histological analysis in survived animals of all experimental groups, being less pronounced in animals receiving 200mg/kg of LAS, reinforcing the importance of this dose against tissue damage induced by PQ. The results allow us to suggest that LAS should be considered in the hospital treatment of PQ poisonings.

Toxicological evaluation of lactose and chitosan delivered by inhalation

These days, inhalation constitutes a promising administration route for many drugs. However, this route exhibits unique limitations, and formulations aimed at pulmonary delivery should include as few as possible additives in order to maintain lung functionality. The purpose of this work was to investigate the safety of lactose and chitosan to the pulmonary tissue when delivered by inhalation. The study was carried out with 18 Wistar rats divided in three groups receiving distilled water, lactose or chitosan. A solution of each excipient was administered by inhalation at a dose of 20 mg. The lungs were excised and processed to determine several biochemical parameters used as toxicity biomarkers. Protein and carbonyl group content, lipid peroxidation, reduced and oxidized glutathione (GSSG), myeloperoxidase (MPO), cooper/zinc and manganese superoxide dismutase, catalase, glutathione S-transferase and glutathione peroxidase were determined. Results of myeloperoxidase activity and glutathione disulfide lung concentrations showed a relevant decrease for chitosan group compared to control: 4.67 +/- 2.27 versus 15.10 +/- 7.27 (P = 0.011) for MPO and 0.89 +/- 0.68 versus 2.02 +/- 0.22 (P = 0.014) for GSSG. The other parameters did not vary significantly among groups. Lactose and chitosan administered by inhalation failed to show toxic effects to the pulmonary tissue. A protective effect against oxidative stress might even be attributed to chitosan, since some biomarkers had values significantly lower than those observed in the control group when this product was inhaled. Nevertheless, caution must be taken regarding chemical composition and technological processes applied to incorporate these products during drug formulation, in particular for dry powder inhalators.

Paraquat poisonings: mechanisms of lung toxicity, clinical features, and treatment

Paraquat dichloride (methyl viologen; PQ) is an effective and widely used herbicide that has a proven safety record when appropriately applied to eliminate weeds. However, over the last decades, there have been numerous fatalities, mainly caused by accidental or voluntary ingestion. PQ poisoning is an extremely frustrating condition to manage clinically, due to the elevated morbidity and mortality observed so far and due to the lack of effective treatments to be used in humans. PQ mainly accumulates in the lung (pulmonary concentrations can be 6 to 10 times higher than those in the plasma), where it is retained even when blood levels start to decrease. The pulmonary effects can be explained by the participation of the polyamine transport system abundantly expressed in the membrane of alveolar cells type I, II, and Clara cells. Further downstream at the toxicodynamic level, the main molecular mechanism of PQ toxicity is based on redox cycling and intracellular oxidative stress generation. With this review we aimed to collect and describe the most pertinent and significant findings published in established scientific publications since the discovery of PQ, focusing on the most recent developments related to PQ lung toxicity and their relevance to the treatment of human poisonings. Considerable space is also dedicated to techniques for prognosis prediction, since these could allow development of rigorous clinical protocols that may produce comparable data for the evaluation of proposed therapies.

Sodium salicylate prevents paraquat-induced apoptosis in the rat lung

The nonselective contact herbicide, paraquat (PQ), is a strong pneumotoxicant, especially due to its accumulation in the lung through a polyamine uptake system and to its capacity to induce redox cycling, leading to oxidative stress-related damage. In the present study, we aimed to investigate the occurrence of apoptotic events in the lungs of male Wistar rats, 24, 48, and 96 h after PQ exposure (25 mg/kg ip) as well as the putative healing effects provided by sodium salicylate [(NaSAL), 200 mg/kg ip] when administered 2 h after PQ. PQ exposure resulted in marked lung apoptosis, in a time-dependent manner, characterized by the "ladder-like" pattern of DNA observed through electrophoresis and by the presence of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL)-positive cells (TPC) as revealed by immunohistochemistry. The two main caspase cascades (the extrinsic receptor-mediated and the intrinsic mitochondria-mediated) and the expressions of p53 and activator protein-1 (AP-1) were also evaluated, to obtain an insight into apoptotic cellular signaling. PQ-exposed rats suffered a time-dependent increase of caspase-3 and caspase-8 and a decrease of caspase-1 activities in lungs compared to the control group. A marked mitochondrial dysfunction evidenced by cytochrome c (Cyt c) release was also observed as a consequence of PQ exposure. In addition, fluorescence electrophoretic mobility shift assay (fEMSA) revealed a transcriptional induction of the p53 and AP-1 transcription factors in a time-dependent manner as a consequence of PQ exposure. NaSAL treatment resulted in the remission of the observed apoptotic signaling and consequently of lung apoptosis. Taken together, the present results showed that PQ activates several events involved in the apoptotic pathways, which might contribute to its lung toxicodynamics. NaSAL, a recently implemented antidote for PQ intoxications, proved to protect lungs from PQ-induced apoptosis.

Neurotoxicity mechanisms of thioether ecstasy metabolites

3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy"), is a widely abused, psychoactive recreational drug that is known to induce neurotoxic effects. Human and rat hepatic metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, which are both catechols that can undergo oxidation to the corresponding ortho-quinones. Ortho-quinones may be conjugated with glutathione (GSH) to form glutathionyl adducts, which can be transported into the brain and metabolized to the correspondent N-acetylcysteine (NAC) adducts. In this study we evaluated the neurotoxicity of nine MDMA metabolites, obtained by synthesis: N-Me-alpha-MeDA, alpha-MeDA and their correspondent GSH and NAC adducts. The studies were conducted in rat cortical neuronal cultures, for a 6 h of exposure period, under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Our findings show that thioether MDMA metabolites are strong neurotoxins, significantly more than their correspondent parent catechols. On the other hand, N-Me-alpha-MeDA and alpha-MeDA are more neurotoxic than MDMA. GSH and NAC conjugates of N-Me-alpha-MeDA and alpha-MeDA induced a concentration dependent delayed neuronal death, accompanied by activation of caspase 3, which occurred earlier in hyperthermic conditions. Furthermore, thioether MDMA metabolites time-dependently increased the production of reactive species, concentration-dependently depleted intracellular GSH and increased protein bound quinones. Finally, thioether MDMA metabolites induced neuronal death and oxidative stress was prevented by NAC, an antioxidant and GSH precursor. This study provides new insights into the neurotoxicity mechanisms of thioether MDMA metabolites and highlights their importance in "ecstasy" neurotoxicity.

Full survival of paraquat-exposed rats after treatment with sodium salicylate

Over the past decades, there have been numerous fatalities resulting from accidental or voluntary ingestion of the widely used herbicide paraquat dichloride (methyl viologen; PQ). Considering that the main target organ for PQ toxicity is the lung and involves the production of reactive oxygen and nitrogen species, inflammation, disseminated intravascular coagulation, and activation of transcriptional regulatory mechanisms, it may be hypothesized that an antidote against PQ poisonings should counteract all these effects. For this purpose, sodium salicylate (NaSAL) may constitute an adequate therapeutic drug, due to its ability to modulate inflammatory signaling systems and to prevent oxidative stress. To test this hypothesis, NaSAL (200 mg/kg ip) was injected in rats 2 h after exposure to a toxic dose of PQ (25 mg/kg, ip). NaSAL treatment caused a significant reduction in PQ-induced oxidative stress, platelet activation, and nuclear factor (NF)-kappaB activation in lung. In addition, histopathological lesions induced by PQ in lung were strongly attenuated and the oxidant-induced increases of glutathione peroxidase and catalase expression became absent. These effects were associated with a full survival of the PQ-treated rats (extended for more than 30 days) in comparison with 100% of mortality by Day 6 in animals exposed only to PQ, suggesting that NaSAL constitutes an important and valuable therapeutic drug to be used against PQ-induced toxicity. Indeed, NaSAL constitutes the first compound with such degree of success (100% survival).

P-glycoprotein induction: an antidotal pathway for paraquat-induced lung toxicity

The widespread use of the nonselective contact herbicide paraquat (PQ) has been the cause of thousands of deaths from both accidental and voluntary ingestion. The main target organ for PQ toxicity is the lung. No antidote or effective treatment to decrease PQ accumulation in the lung or to disrupt its toxicity has yet been developed. The present study describes a procedure that leads to a remarkable decrease in PQ accumulation in the lung, together with an increase in its fecal excretion and a subsequent decrease in several biochemical and histopathological biomarkers of toxicity. The administration of dexamethasone (100 mg/kg ip) to Wistar rats, 2 h after PQ intoxication (25 mg/kg ip), decreased the lung PQ accumulation to about 40% of the group exposed to only PQ and led to an improvement in tissue healing in just 24 h as a result of the induction of de novo synthesis of P-glycoprotein (P-gp). The involvement of P-gp in these effects was confirmed by Western blot analysis and by the use of a competitive inhibitor of this transporter, verapamil (10 mg/kg ip), which, given 1 h before dexamethasone, blocked its protective effects, causing instead an increase in lung PQ concentration and an aggravation of toxicity. In conclusion, the induction of P-gp, leading to a decrease in lung levels of PQ and the consequent prevention of toxicity, seems to be a new and promising treatment for PQ poisonings that should be further clinically tested.

Kinetics of paraquat in the isolated rat lung: Influence of sodium depletion

Paraquat accumulates in the lung through a characteristic polyamine uptake system. It has been previously shown that paraquat uptake can be significantly prevented if extracellular sodium (Na+) is reduced, although the available data correspond to experiments performed using tissue slices or incubated cells. This type of in vitro study fails to give information on the actual behaviour occurring in vivo since the anatomy and physiology of the studied tissue is disrupted. Accordingly, the aim of the present study was to explore the usefulness of the isolated rat lung model when applied to characterize the kinetic behaviour of paraquat in this tissue after bolus injection under standard experimental conditions as well as to evaluate the influence of iso-osmotic replacement of Na+ by lithium (Li+) in the perfusion medium. The obtained results show that the present isolated rat lung model is useful for the analysis of paraquat toxicokinetics, which is reported herein for the first time. It was also observed that Na+ depletion in the perfusion medium leads to a decreased uptake of paraquat in the isolated rat lung, although it seems that this condition does not contribute to improve the elimination of paraquat once the herbicide reaches the extravascular structures of the tissue, since the paraquat tissue wash-out phase is similar under both experimental conditions assayed.

Paraquat exposure as an etiological factor of Parkinson's disease

Parkinson's disease (PD) is a multifactorial chronic progressive neurodegenerative disease influenced by age, and by genetic and environmental factors. The role of genetic predisposition in PD has been increasingly acknowledged and a number of relevant genes have been identified (e.g., genes encoding alpha-synuclein, parkin, and dardarin), while the search for environmental factors that influence the pathogenesis of PD has only recently begun to escalate. In recent years, the investigation on paraquat (PQ) toxicity has suggested that this herbicide might be an environmental factor contributing to this neurodegenerative disorder. Although the biochemical mechanism through which PQ causes neurodegeneration in PD is not yet fully understood, PQ-induced lipid peroxidation and consequent cell death of dopaminergic neurons can be responsible for the onset of the Parkinsonian syndrome, thus indicating that this herbicide may induce PD or influence its natural course. PQ has also been recently considered as an eligible candidate for inducing the Parkinsonian syndrome in laboratory animals, and can therefore constitute an alternative tool in suitable animal models for the study of PD. In the present review, the recent evidences linking PQ exposure with PD development are discussed, with the aim of encouraging new perspectives and further investigation on the involvement of environmental agents in PD.

Ecstasy-induced cell death in cortical neuronal cultures is serotonin 2A-receptor-dependent and potentiated under hyperthermia

Studies on 3,4-methylenedioxymethamphetamine ("ecstasy")-induced neurotoxicity mainly focus on damage of serotonergic terminals. Less attention has been given to neuronal cell death produced by 3,4-methylenedioxymethamphetamine and other amphetamines in areas including the cortex, striatum and thalamus. In the present study we investigated 3,4-methylenedioxymethamphetamine-induced neurotoxicity in neuronal serum free cultures from rat cortex. Since 3,4-methylenedioxymethamphetamine intake induces hyperthermia in both animals and humans, the experiments were performed under normal (36.5 degrees C) and hyperthermic conditions (40 degrees C). Our findings showed a dose-, time- and temperature-dependent apoptotic cell death induced by 3,4-methylenedioxymethamphetamine in cortical neurons. 3,4-Methylenedioxymethamphetamine-induced damage was potentiated under hyperthermia. The neurotoxicity was reduced by the serotonin 2A-receptor antagonists, ketanserin and (2R,4R)-5-[2-[2-[2-(3-methoxyphenyl)ethyl]phenoxy]ethyl]-1-methyl-3-pyrrolidinol hydrochloride, in both normothermic and hyperthermic conditions. (+/-)-2,5-Dimethoxy-4-iodoamphetamine hydrochloride, a model agonist for the serotonin 2A-receptor, also induced a dose- and time-dependent apoptotic cell death. Again, protection was provided by ketanserin and (2R,4R)-5-[2-[2-[2-(3-methoxyphenyl)ethyl]phenoxy]ethyl]-1-methyl-3-pyrrolidinol hydrochloride against (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride-induced neurotoxicity, thereby indicating that the 3,4-methylenedioxymethamphetamine stimulation of the serotonin 2A-receptor leads to neurotoxicity. This study provides for the first time evidence that direct 3,4-methylenedioxymethamphetamine serotonin 2A-receptor stimulation leads to neuronal cortical death. alpha-Phenyl-N-tert-butyl nitrone a free radical scavenger and the nitric oxide synthase inhibitor Nomega-nitro-L-arginine as well as the NMDA-receptor antagonist MK-801 provided protection under normothermia and hyperthermia, thereby suggesting the participation of free radicals in 3,4-methylenedioxymethamphetamine-induced cell death. Since 3,4-methylenedioxymethamphetamine serotonin 2A-receptor agonistic properties lead to neuronal death, clinically available atypical antipsychotic drugs with serotonin 2A-antagonistic properties could be a valuable therapeutic tool against 3,4-methylenedioxymethamphetamine-induced neurodegeneration.

D-amphetamine-induced hydrogen peroxide production in skeletal muscle is modulated by monoamine oxidase inhibition

The aim of this paper was to study the influence of d-amphetamine administration as a sympathomimetic drug on the synthesis of hydrogen peroxide (H2O2) in mouse soleus muscle and to investigate the modulating effects of pargyline, an inhibitor of monoamine oxidase (MAO) in this context. Charles River mice were assigned to four groups: Control, d-amphetamine treated, pargyline treated, and amphetamine + pargyline treated. Their soleus muscles were removed 0, 15, 30, 60, and 120 min after treatment. The amount of hydrogen peroxide formation within the muscles was estimated using an indirect method. The control data showed a continuous production of hydrogen peroxidase. Pargyline administration lead to an initial increase of H2O2 production that later faded below control levels. Administration of amphetamine finally stimulated H2O2 production much above control levels. When combining amphetamine and pargyline treatment, H2O2 production was accelerated in the initial phase but dropped to control levels at 30 min. It is concluded that in skeletal muscle MAO is an important source of hydrogen peroxide production triggered by amphetamine administration and that this tissue plays a hitherto not described role in oxidizing circulating biogenic monoamines.

N-t-Boc-amino acid esters of isomannide Potential inhibitors of serine proteases

Hepatitis C, Dengue and West Nile virus are some of the most important flaviviruses, that share one important serine protease enzyme. Serine proteases are the most studied class of proteolytic enzyme and, in these cases, a primary target for drug discovery. In this paper, we describe the synthesis and preliminary molecular modeling studies of a novel class of N- t-Boc amino acid esters derived of isomannide as potential serine proteases inhibitors.

Evaluation of toxic/protective effects of the essential oil of Salvia officinalis on freshly isolated rat hepatocytes

For this study the essential oil (EO) of sage (Salvia officinalis L.) was isolated from air-dried vegetative aerial parts of the plants by hydrodistillation and analysed by GC and GC-MS. A total yield of 12.07 mg of EO per g of plant dry mass was obtained and more than 50 compounds identified. The major compounds were cis-thujone (17.4%), alpha-humulene (13.3%), 1,8-cineole (12.7%), E-caryophyllene (8.5%) and borneol (8.3%). The EO fraction of sage tea was also isolated by partition with pentane and the respective components identified. The toxic and antioxidant protective effects of S. officinalis EO were evaluated on freshly isolated rat hepatocytes. Cell viability (LDH leakage), lipid peroxidation and glutathione status were measured in experiments undertaken with cells (suspensions of 1 x 10(6) cells per millilitre) exposed to EO alone (toxicity of the EO;t-BHP as positive control); and with cells exposed to EO and an oxidative compound (t-BHP) together (in EO protection evaluation; quercetin as positive control) for 30 min. The results show that the EO is not toxic when present at concentrations below 200 nl/ml; it was only at 2000 nl EO/ml that a significant LDH leakage and GSH decrease were observed indicating cell damage. In the range of concentrations tested, the EO did not show protective effects against t-BHP-induced toxicity.

Simultaneous determination of amphetamine derivatives in human urine after SPE extraction and HPLC-UV analysis

Amphetamine derivatives are a class of compounds increasingly abused as recreational drugs in various regions of the world. Although d-amphetamine (AMPH) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are among the most commonly used, the abuse of other designer drugs such as 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and 4-methylthioamphetamine (4-MTA) and their involvement in acute intoxications has been increasingly reported. There is evidence that abusers ingest these compounds either alone or in combination and the respective monitoring is important for both legal and health care purposes in hospital emergency. In the present study a simple and clean solid-phase extraction procedure from urine of AMPH and MDMA, and their major metabolites p-hydroxyamphetamine (OH-AMPH) and methylenedioxyamphetamine (MDA) and 2C-B and 4-MTA was developed. Analysis was performed by HPLC-UV and the precision of the technique was between 2.9 and 5.3% for all compounds. For the overall procedure, the precision values were between 3.3 and 5.9%. Recoveries obtained from spiked urines at three concentration levels were better than 84 +/- 4% for the six compounds. The limit of detection of the method for the compounds (between 5.3 and 84.0 ng) enables their identification in urine after ingestion of fatal and non-fatal doses. The main advantages of the present method lie in its simple, clean and reliable SPE extraction method of the six amphetamine derivatives from urine followed by their simultaneous detection and quantification by liquid chromatography with UV detection.

Hydroxyl radical and hypochlorous acid scavenging activity of small centaury (Centaurium erythraea) infusion. A comparative study with green tea (Camellia sinensis)

Small centaury (Centaurium erythraea Rafin.) is a herbal species with a long use in traditional medicine due to its digestive, stomachic, tonic, depurative, sedative and antipyretic properties. This species is reported to contain considerable amounts of polyphenolic compounds, namely xanthones and phenolic acids as the main constituents. Although the antiradicalar activity of some pure polyphenolic compounds is already known, it remains unclear how a complex mixture obtained from plant extracts functions against reactive oxygen species. Thus, the ability of small centaury infusion to act as a scavenger of the reactive oxygen species hydroxyl radical and hypochlorous acid was studied and compared with that of green tea (Camellia sinensis L.). Hydroxyl radical was generated in the presence of Fe3+-EDTA, ascorbate and H2O2 (Fenton system) and monitored by evaluating hydroxyl radical-induced deoxyribose degradation. The reactivity towards hypochlorous acid was determined by measuring the inhibition of hypochlorous acid-induced 5-thio-2-nitrobenzoic acid oxidation to 5,5'-dithiobis(2-nitrobenzoic acid). The obtained results demonstrate that small centaury infusion exhibits interesting antioxidant properties, expressed both by its capacity to effectively scavenge hydroxyl radical and hypochlorous acid, although with a lower activity against the second than that observed for green tea. Green tea exhibited a dual effect at the hydroxyl radical scavenging assay, stimulating deoxyribose degradation at lower dosages.

Copper enhances isoproterenol toxicity in isolated rat cardiomyocytes: effects on oxidative stress

Sustained high levels of circulating catecholamines may result in cardiotoxicity. Although cardiotoxicity could occur primarily via adrenoceptor activation, there is increasing evidence that it may also occur through oxidative mechanisms. In fact, catecholamines can be converted into aminochromes by auto-oxidation, enzymatically or metal catalyzed, with the concomitant production of reactive intermediates and free radicals. Nevertheless, there is only scarce information concerning the effects of the catecholamine oxidation process on isolated cardiomyocytes. The aim of this work was to evaluate the cardiotoxic effects of isoproterenol (ISO) and its oxidation process in freshly isolated adult rat cardiomyocytes by assessing the cell shape, lactate dehydrogenase leakage, reduced and oxidized glutathione content, and glutathione reductase, peroxidase, and transferase activities. ISO was incubated at concentrations of 0.1, 0.5, and 1 mM in cardiomyocyte suspensions at subphysiological and physiological Ca2+ concentrations for 4 h. The same study was repeated in the presence of 20 microM of Cu2+. The levels of ISO in the incubation medium were monitored throughout the assays. Isoproterenol (1 mM) induced both glutathione oxidation and conjugation, but this effect decreased at subphysiological Ca2+ concentrations. The concomitant incubation with Cu2+ increased ISO oxidation and increased the glutathione oxidation but decreased the extent of glutathione conjugation. Although only a partial ISO oxidation was observed for all studied ISO concentrations in the presence of copper, the underlying oxidative process or its oxidation products, or both, were sufficient to induce a loss of cardiomyocyte viability and a decrease in the glutathione reductase, peroxidase, and transferase activities. Thus, the results suggest that the oxidation of catecholamines could be a major mechanism for catecholamine-induced cardiotoxicity.

Determination of amphetamine and its metabolite p-hydroxyamphetamine in rat urine by reversed-phase high-performance liquid chromatography after dabsyl derivatization

The consumption of amphetamine is illicit and controlled due to both the elicited behavioural deviations and the toxicity effects reported in abusers. Thus, amphetamine levels in biological samples must be monitored in several clinical and forensic circumstances. In spite of the interspecies differences in the preferred route of biotransformation, benzylmethylketone, benzoic acid and 4-hydroxyamphetamine are the principal metabolites of amphetamine. However, the clinical and forensic studies are focused in the parent compound and in 4-hydroxyamphetamine since benzylmethylketone is a minor metabolite in human and benzoic acid is also an endogenous compound. In the present study amphetamine and its metabolite, 4-hydroxyamphetamine, are quantified in urine by HPLC after derivatization with 4-dimethylaminoazobenzene-4'-sulfonyl chloride (dabsyl chloride). This derivatization procedure transforms amphetamine and its hydroxylated metabolite in compounds with similar lipofilicity, enabling their quantitative and simultaneous extraction with an organic solvent. The precision of the HPLC technique was 7.3 and 10.0% for amphetamine and 4-hydroxyamphetamine derivatives, respectively. For the overall procedure, including enzymatic hydrolysis, derivatization and extraction of the derivatives, the obtained values were 9.3 and 6.2%. Recoveries obtained from spiked urines for amphetamine and 4-hydroxyamphetamine were better than 97% and 94% (mean value), respectively. The detection limits of the method was 10 ng for both compounds. The principal advantages of the present proposed method are the stability of the dabsyl derivatives at room temperature and the detection carried out in the visible region, reducing the interferences detected.

Hydrogen peroxide production in mouse tissues after acute d-amphetamine administration. Influence of monoamine oxidase inhibition

The toxicity of amphetamines is conditioned by a complex array of mechanisms, involving the increase of neurotransmission (e.g. leading to hyperthermia) and enzymatic and non-enzymatic oxidation of amphetamines and biogenic amines. Considering that all these processes may increase the generation of hydrogen peroxide (H2O2) by metabolic or non-metabolic redox pathways, the main objective of this work was to evaluate d-amphetamine-induced H2O2 production in mice liver, kidney and heart. The contribution of monoamine oxidase (MAO) to H2O2 production after d-amphetamine administration was studied using the MAO inhibitor pargyline. H2O2 production was measured indirectly using the catalase-H2O2 complex I irreversible inhibitor 3-amino-1,2,4-triazole (AT). Using this method, the measurement of residual catalase activity following administration of AT permits the monitoring of H2O2 production in vivo. Charles River CD-1 mice (30-35 g body weight) were injected with AT just before the injection of d-amphetamine sulphate (20 mg/kg). d-Amphetamine stimulated the production of H2O2 in all tissues studied, although to different degrees. MAO inhibition by itself led to a remarkable decrease of basal H2O2 production in the kidney and a slight decrease in the liver, although no effect was observed in the heart. d-Amphetamine-induced H2O2 production in the heart and kidney was reduced in MAO-inhibited mice. However, in the liver, H2O2 production was transiently potentiated at 30 min under MAO inhibition. In conclusion, d-amphetamine administration leads to an increase in H2O2 production in mouse liver, kidney and heart, and monoamine oxidase plays an important role in this effect.

The study of oxidative stress in freshly isolated Ca(2+)-tolerant cardiomyocytes from the adult rat

Cardiotoxicity studies using isolated heart cells are becoming increasingly advocated as a supplement to, and sometimes as a replacement for, whole heart or whole animal experimentation. In fact, the use of isolated cardiomyocytes has the great advantage of enabling mechanistic and comparative studies of compounds, which are directly toxic to cardiomyocytes. Since the 1970s, different procedures have been developed in order to obtain Ca(2+)-tolerant cardiomyocytes. The advances in this field will be reviewed and an optimised method to obtain freshly isolated Ca(2+)-tolerant cardiomyocytes from the adult rat for use in toxicological studies will be described. With this procedure, a high number of rod-shaped cells can be obtained (6-7 x 10(6)/heart corresponding to 70% of total number of cells). It is also possible to maintain cell viability, glutathione content and enzymatic activity of glutathione reductase (GR), glutathione peroxidase (GPX) and glutathione S-transferase (GST) in acceptable levels for 4 hours. Cardiotoxicity studies performed with isoproterenol (ISO) in the presence of copper and with the model toxic substance tert-butylhydroperoxide (t-BHP) demonstrate the importance of oxidative stress as a cardiotoxic mechanism elicited by these molecules. The results obtained are also good indicators for future applications of this methodology to other cardiotoxicity studies.