Derivation of internal dose-based thresholds of toxicological concern for occupational inhalation exposure to systemically acting organic chemicals

This study aimed at deriving occupational thresholds of toxicological concern for inhalation exposure to systemically-acting organic chemicals using predicted internal doses. The latter were also used to evaluate the quantitative relationship between occupational exposure limit and internal dose. Three internal dose measures were identified for investigation: (i) the daily area under the venous blood concentration vs. time curve, (ii) the daily rate of the amount of parent chemical metabolized, and (iii) the maximum venous blood concentration at the end of an 8-hr work shift. A dataset of 276 organic chemicals with 8-hr threshold limit values-time-weighted average was compiled along with their molecular structure and Cramer classes (Class I: low toxicity, Class II: intermediate toxicity, Class III: suggestive of significant toxicity). Using a human physiologically-based pharmacokinetic model, the three identified dose metrics were predicted for an 8-hr occupational inhalation exposure to the threshold limit value for each chemical. Distributional analyses of the predicted dose metrics were performed to identify the percentile values corresponding to the occupational thresholds of toxicological concern. Also, simple linear regression analyses were performed to evaluate the relationship between the 8-hr threshold limit value and each of the predicted dose metrics, respectively. No threshold of toxicological concern could be derived for class II due to few chemicals. Based on the daily rate of the amount of parent chemical metabolized, the proposed internal dose-based occupational thresholds of toxicological concern were 5.61?×?10^?2 and 9?×?10^?4 mmol/d at the 10th percentile level for classes I and III, respectively, while they were 4.55?×?10^?1 and 8.5?×?10^?3 mmol/d at the 25th percentile level. Even though high and significant correlations were observed between the 8-hr threshold limit values and the predicted dose metrics, the one with the rate of the amount of chemical metabolized was remarkable regardless of the Cramer class (r² = 0.81; n = 276). The proposed internal dose-based occupational thresholds of toxicological concern are potentially useful for screening-level assessments as well as prioritization within an integrated occupational risk assessment framework.     

Outcome of patients hospitalized for COVID‐19 and exposure to angiotensin‐converting enzyme inhibitors and angiotensin‐receptor blockers in France: results of the ACE‐CoV study

Data are lacking on the impact of ACEI/ARB exposure on unfavorable outcome in the population of patients hospitalized for COVID‐19 with hypertension/cardiovascular disease, particularly in Europe. The ACE‐CoV study was designed to assess this question. The study was conducted in the Covid‐Clinic‐Toul cohort, which contains data about all patients hospitalized at Toulouse University hospital, France with a SARS‐CoV‐2 infection since March, 2020. We selected the patients with a history of cardiovascular disease (heart failure or coronary disease) and/or arterial hypertension. We conducted a subgroup analysis in patients with arterial hypertension. ACEI/ARB exposures at admission were assessed. The outcome was composite: admission to intensive care unit, need of mechanical ventilation or death during the 14 days after admission to hospital. We used logistic regression models with propensity scores (PS) weighted by overlap weighting (OW) and inverse probability of treatment weighting (IPTW). Between March 2020 and April 20, 2020, the Covid‐Clinic‐Toul included 263 patients. Among them, 111 were included in the ACE‐CoV study population. In OW‐PS‐adjusted analyses, the association of exposure to ACEIs or ARBs with outcome occurrence was OR: 1.56 (95% CI: 0.73–3.33). It was 0.99 (95% CI: 0.68–1.45) for ACEIs and 1.64 (95% CI: 0.77–3.50) for ARBs. Analyses with weighting by the IPTW‐PS method gave similar results. Results were similar when considering the subgroup of patients with arterial hypertension. The ACE‐CoV study found no association between exposure to ACEIs or ARBs and unfavorable outcome in hospitalized patients for COVID‐19 with a history of cardiovascular disease/arterial hypertension.     

Intracellular Phosphate and ATP Depletion Measured by Magnetic Resonance Spectroscopy in Patients Receiving Maintenance Hemodialysis

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Utility of food pellets containing 1-aminobenzotriazole for longer term in vivo inhibition of cytochrome P450 in mice

1. The utility of 1-aminobenzotriazole (ABT), incorporated in food, has been investigated as an approach for longer term inhibition of cytochrome P450 (P450) enzymes in mice.

2. In rats, ABT inhibits gastric emptying, to investigate this potential limitation in mice we examined the effect of ABT administration on the oral absorption of NVS-CRF38. Two hour prior oral treatment with 100?mg/kg ABT inhibited the oral absorption of NVS-CRF38, T_max was 4?hours for ABT-treated mice compared to 0.5?hours in the control group.

3. A marked inhibition of hepatic P450 activity was observed in mice fed with ABT containing food pellets for 1?month. P450 activity, as measured by the oral clearance of antipyrine, was inhibited on day 3 (88% of control), week 2 (83% of control) and week 4 (80% of control).

4. T_max values for antipyrine were comparable between ABT-treated mice and the control group, alleviating concerns about impaired gastric function.

5. Inclusion of ABT in food provides a minimally invasive and convenient approach to achieve longer term inhibition of P450 activity in mice. This model has the potential to enable pharmacological proof-of-concept studies for research compounds which are extensively metabolised by P450 enzymes.