Biology subjects

Tour, J. M.

Publications and source records attributed to Tour, J. M..

3 recordsLinked to original sources

bioRxiv2024

Microbicidal Mechanisms for Light-Activated Molecular Nanomachines in Mycobacterium smegmatis: A Model for Pathogenic Bacteria

There is a global health crisis of antimicrobial resistance, with over a million deaths annually attributed to antimicrobial-resistant pathogens, and mycobacterial infections are a major cause of antimicrobial-resistant infections, leading to more deaths than any other single infectious agent. Notably, the rise of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) strains of Mycobacterium tuberculosis led to higher mortality rates and challenge all existing antibiotic regimens. Light-activated molecular nanomachines (MNMs) represent a promising class of broad-spectrum antimicrobial agents that could help counter this rise in antimicrobial resistance. Addressing a key knowledge gap, this study explores the mechanisms of action for MNMs in Mycobacterium smegmatis, a surrogate model for pathogenic mycobacteria. We show that fast rotor MNMs kill up to 97% of M. smegmatis and co-localize with the bacteria as part of their mechanism of action. The ability to translate these observations to pathogenic mycobacteria was demonstrated by the ability of MNMs to kill 93.5% of M. tuberculosis under similar conditions. These findings suggest that MNMs may provide innovative sustainable antimicrobial agents for the treatment of drug-resistant mycobacterial infections. Graphical AbstractBacteria exposed to MNMs have two distinct outcomes when activated by 365 nm light. Slow motors (MNM 2 and 4) have no rotational action, remains outside the bacteria and have little to no effect on bacterial viability. Whereas fast motors (MNM 1 and 3) co-localize and embed into the bacterial cell wall causing disruptions that lead to a significant reduction in bacterial viability. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/616754v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@70991corg.highwire.dtl.DTLVardef@541a36org.highwire.dtl.DTLVardef@18504bcorg.highwire.dtl.DTLVardef@1fa08c3_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2023

Molecular Jackhammers Eradicate Cancer Cells by Vibronic-Driven Action

Through the actuation of vibronic modes in cell-membrane-associated aminocyanines, a new type of molecular mechanical action can be exploited to rapidly kill cells by necrosis. This is done using near-infrared light, a low energy source hitherto thought to be insufficient to permit molecular mechanical disruption of a cell membrane. Vibronic-driven action (VDA) is distinct from both photodynamic therapy and photothermal therapy in that the VDA mechanical effect on the cell membrane is not retarded by high doses of inhibitors of reactive oxygen species (ROS), and VDA does not itself induce an increase in the temperature of the media; it is also unaffected by cooling the media to 2 {degrees}C. The picosecond concerted whole-molecule-vibrations of VDA-induced mechanical disruption can be done with very low concentrations (500 nM) of the aminocyanines or low doses of light (12 Jcm-2, 80 mWcm-2 for 2.5 min) to cause in vitro necrotic cell death in >99% of human melanoma cells. The effect is also studied in vivo in murine B16-F10 and human A375 melanoma in mice, underscoring the high efficiency of this approach, achieving a survival rate of 60% at day 120, and 50% of the mice becoming tumor free. The molecules that destroy cell membranes through VDA are termed molecular jackhammers (MJH) because they undergo concerted whole-molecule vibrations. Different than traditional chemotherapy, it is unlikely that a cell could develop a resistance to molecular mechanical forces, thereby providing a new modality for inducing cancer cell death.

bioengineering↗

bioRxiv2018

Enteral Activation of WR-2721 Mediates Radioprotection and Improved Survival from Lethal Fractionated Radiation

Unresectable pancreatic cancer is almost universally lethal because chemotherapy and radiation cannot completely stop the growth of the cancer. The major problem with using radiation to approximate surgery in unresectable disease is that the radiation dose required to ablate pancreatic cancer exceeds the tolerance of the nearby duodenum. WR-2721, also known as amifostine, is a well-known radioprotector, but has significant clinical toxicities when given systemically. WR-2721 is a prodrug and is converted to its active metabolite, WR-1065, by alkaline phosphatases in normal tissues. The small intestine is highly enriched in these activating enzymes, and thus we reasoned that oral administration of WR-2721 just before radiation would result in localized production of the radioprotective WR-1065 in the small intestine, providing protective benefits without the significant systemic side effects. Here, we show that oral WR-2721 is as effective as intraperitoneal WR-2721 in promoting survival of intestinal crypt clonogens after morbid irradiation. Furthermore, oral WR-2721 confers full radioprotection and survival after lethal upper abdominal irradiation of 12.5Gy x 5 fractions (total of 62.5Gy, D2EQ=140.6Gy), which would likely ablate pancreatic cancer. We find that the efficacy of oral WR-2721 stems from its selective accumulation in the intestine, but not in tumors or other normal tissues, as determined by in vivo mass spectrometry analysis. Thus, we demonstrate that oral WR-2721 is a well-tolerated, and quantitatively selective, radioprotector of the intestinal tract that is capable of enabling clinically relevant ablative doses of radiation to the upper abdomen without unacceptable gastrointestinal toxicity.

cancer biology↗