BEAMS Lab at MIT: Status report

The Biological Engineering Accelerator Mass Spectrometry (BEAMS) Lab at the Massachusetts Institute of Technology is a facility dedicated to incorporating AMS into life sciences research. As such, it is focused exclusively on radiocarbon and tritium AMS and makes use of a particularly compact instrument of a size compatible with most laboratory space. Recent developments at the BEAMS Lab were aimed to improve different stages of the measurement process, such as the carbon sample injection interface, the simultaneous detection of tritium and hydrogen and finally, the overall operation of the system. Upgrades and results of those efforts are presented here.United States. National Institutes of Health (grant P30-ES02109)United States. National Institutes of Health (grant R42-CA084688)National Institutes of Health. National Center for Research Resources (grant UL1 RR 025005)GlaxoSmithKlin

Monocyclic aromatic amines as potential human carcinogens: old is new again

Alkylanilines are a group of chemicals whose ubiquitous presence in the environment is a result of the multitude of sources from which they originate. Exposure assessments indicate that most individuals experience lifelong exposure to these compounds. Many alkylanilines have biological activity similar to that of the carcinogenic multi-ring aromatic amines. This review provides an overview of human exposure and biological effects. It also describes recent investigations into the biochemical mechanisms of action that lead to the assessment that they are most probably more complex than those of the more extensively investigated multi-ring aromatic amines. Not only is nitrenium ion chemistry implicated in DNA damage by alkylanilines but also reactions involving quinone imines and perhaps reactive oxygen species. Recent results described here indicate that alkylanilines can be potent genotoxins for cultured mammalian cells when activated by exogenous or endogenous phase I and phase II xenobiotic-metabolizing enzymes. The nature of specific DNA damage products responsible for mutagenicity remains to be identified but evidence to date supports mechanisms of activation through obligatory N-hydroxylation as well as subsequent conjugation by sulfation and/or acetylation. A fuller understanding of the mechanisms of alkylaniline genotoxicity is expected to provide important insights into the environmental and genetic origins of one or more human cancers and may reveal a substantial role for this group of compounds as potential human chemical carcinogens.National Institute of Environmental Health Sciences (PO1-ES006052)National Institute of Environmental Health Sciences (P30-ES002109

Purification of the food-borne carcinogens 2-amino-3-methylimidazo [4,5-f]quinoline and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in heated meat products by immunoaffinity chromatography

A rapid and simple scheme has been developed for the isolation and purification of two of the major mutagenic heterocyclic amines formed in heated beef products by affinity chromatography using monoclonal antibodies which recognize 2-amino-3-methylimidazo(4,5-f]quinoline (IQ). Two cell lines producing IgG antibodies were established following fusion of Sp2 or P3x.63 myeloma cells with spleen cells of immunized BALB/cby mice. The antigen was bovine gamma globulin haptenized with 2-(3-carboxypropylthio)-3-methylimidazo[4,5-f]quinoline. The antibodies were immobilized on CNBr-activated Sepharose 4B. IQ and MeIQx formed in heated beef products were partially purified by XAD-2 chromatography and then applied to the affinity columns. Purification by affinity chromatography was adequate for subsequent quantitative analysis by HPLC with UV detection. With this purification scheme as little as 1 g of beef extract or 15 g of fried beef could be assayed for IQ and MeIQx at the part per billion level. Both antibodies had similar affinity constants for IQ (9.3 × 106 and 6.7 × 106 M−1) and for MeIQx (7.1 × 105 and 2.7 × 105 M−1) and both were suitable for immunoaffinity purification of IQ from complex mixtures. MAb2 could be used as well to selectively remove MeIQx from meat products after partial purification by XAD-2. MAb1, despite having a 3-fold higher affinity than MAb2 for MeIQx, could not be used for affinity chromatography for this mutage

Biphasic Elimination of Tenofovir Diphosphate and Nonlinear Pharmacokinetics of Zidovudine Triphosphate in a Microdosing Study

Objective: Phase 0 studies can provide initial pharmacokinetics (PKs) data in humans and help to facilitate early drug development, but their predictive value for standard dosing is controversial. To evaluate the prediction of microdosing for active intracellular drug metabolites, we compared the PK profile of 2 antiretroviral drugs, zidovudine (ZDV) and tenofovir (TFV), in microdose and standard dosing regimens. Study Design: We administered a microdose (100 μg) of [superscript 14]C-labeled drug (ZDV or tenofovir disoproxil fumarate) with or without a standard unlabelled dose (300 mg) to healthy volunteers. Both the parent drug in plasma and the active metabolite, ZDV-triphosphate (ZDV-TP) or TFV-diphosphate (TFV-DP) in peripheral blood mononuclear cells (PBMCs) and CD4[superscript +] cells were measured by accelerator mass spectrometry. Results: The intracellular ZDV-TP concentration increased less than proportionally over the dose range studied (100 μg–300 mg), whereas the intracellular TFV-DP PKs were linear over the same dose range. ZDV-TP concentrations were lower in CD4[superscript +] cells versus total PBMCs, whereas TFV-DP concentrations were not different in CD4[superscript +] cells and PBMCs. Conclusions: Our data were consistent with a rate-limiting step in the intracellular phosphorylation of ZDV but not TFV. Accelerator mass spectrometry shows promise for predicting the PK of active intracellular metabolites of nucleosides, but nonlinearity of PK may be seen with some drugs.Johns Hopkins University (Institute for Clinical and Translational Research CTSA Grant UL1-RR025005

Single Dose Pharmacokinetics of Oral Tenofovir in Plasma, Peripheral Blood Mononuclear Cells, Colonic Tissue, and Vaginal Tissue

HIV seroconversion outcomes in preexposure prophylaxis (PrEP) trials of oral tenofovir (TFV)-containing regimens are highly sensitive to drug concentration, yet less-than-daily dosing regimens are under study. Description of TFV and its active moiety, TFV diphosphate (TFV-DP), in blood, vaginal tissue, and colon tissue may guide the design and interpretation of PrEP clinical trials. Six healthy women were administered a single oral dose of 300 mg tenofovir disoproxil fumarate (TDF) and 4.3 mg (12.31 MBq, 333 μCi) [superscript 14]C-TDF slurry. Blood was collected every 4 h for the first 24 h, then at 4, 8, 11, and 15 days postdosing. Colonic and vaginal samples (tissue, total and CD4+ cells, luminal fluid and cells) were collected 1, 8 and 15 days postdose. Samples were analyzed for TFV and TFV-DP. Plasma TFV demonstrated triphasic decay with terminal elimination half-life median [interquartile range (IQR)] 69 h (58–77). Peripheral blood mononuclear cell (PBMC) TFV-DP demonstrated biphasic peaks (median 12 h and 96 h) followed by a terminal 48 h (38–76) half-life; C[subscript max] was 20 fmol/million cells (2–63). One day postdose, the TFV-DP paired colon:vaginal tissue concentration ratio was 1 or greater in all subjects' tissue homogenates, median 124 (range 1–281), but was not sustained. The ratio was lower and more variable in cells extracted from tissue. Among all sample types, TFV and TFV-DP half-life ranged from 23 to 139 h. PBMC TFV-DP rose slowly in the hours after dosing indicating that success with exposure-driven dosing regimens may be sensitive to timing of the dose prior to exposure. Colonic tissue homogenate TFV-DP concentrations were greater than in vaginal homogenate at 24 h, but not in cells extracted from tissue. These and the other pharmacokinetic findings will guide the interpretation and design of future PrEP trials.National Center for Advancing Translational Sciences (U.S.) (Grant UL1RR025005)National Institutes of Health (U.S.)National Institutes of Health (U.S.) (Roadmap for Medical Research

In vitro bioactivity of titanium-doped bioglass

Previous studies have suggested that incorporating relatively small quantities of titanium dioxide into bioactive glasses may result in an increase in bioactivity and hydroxyapatite formation. The present work therefore investigated the in vitro bioactivity of a titanium doped bioglass and compared the results with 45S5 bioglass. Apatite formation was evaluated for bioglass and Ti-bioglass in the presence and absence of foetal calf serum. Scanning electron microscopy (SEM) images were used to evaluate the surface development and energy dispersive X-ray measurements provided information on the elemental ratios. X-ray diffraction spectra confirmed the presence of apatite formation. Cell viability was assessed for bone marrow stromal cells under direct and indirect contact conditions and cell adhesion was assessed using SEM

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

Background: The EMPA KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population. Methods: EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110. Findings: Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5–2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62–0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16–1·59), representing a 50% (42–58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1). Interpretation: In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease. Funding: Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden