Photoresponsive systems are widespread in nature, and life processes such as photosynthesis, visi... more Photoresponsive systems are widespread in nature, and life processes such as photosynthesis, vision, phototropism, and phototaxis are linked with structural changes of molecules caused by sunlight. Similar photochemical transformations can be employed to render synthetic agrochemicals and drugs active or to govern their bioavailability at the site of action. Related fundamental physical and chemical processes are discussed as part of the introductory paragraph. In agrochemical applications mainly three different ways have been reported as to how light can be utilized to optimize pesticidal effects in crop protection. The hypersensitization of certain pests to sunlight by chemical compounds represents an effective approach and exists also as a natural mechanism of defense. Photo-removable protective groups and various photoreactive structural moieties have successfully been applied for the rational design of light-activated propesticides. Finally, daylight can function as a triggering and governing factor in controlled-release systems based on photoresponsive polymers. Among the major advantages of light-regulated pesticides, the target-directed activation and the inherent detoxification predominate. In biomedical applications, light has also been used to activate compounds to time their action. Although radiation of various types (microwave, X-ray, and gamma radiation) has been used extensively for both treatment and diagnostics, the limited access of UV and visible light to most tissues of the body prevents its general use as the activating trigger. We review here three areas only: cutaneous photobiology-related applications; photoaffinity labeling; and porphyrins as therapeutic agents.
Abstract Precision medicine initiative is an attempt to improve disease treatment and prevention ... more Abstract Precision medicine initiative is an attempt to improve disease treatment and prevention by taking into account individual variability in genes, environment, and lifestyle for each person. Successful application of new knowledge generated by precision medicine will ultimately require the availability of precision drugs: drugs that act exclusively on disease molecular targets without impacting adversely on the rest of the body. This review examines recent progress to developing such site-specific targeting drug systems. Progress to such a goal has been slow. It is concluded that material science needs to take into full consideration the essential properties and requirements of body physiology. In turn, biology needs to define unique features of disease on which effective drug-delivery systems could be based.
ABSTRACT This contribution summarizes the current knowledge about the passive movement of macromo... more ABSTRACT This contribution summarizes the current knowledge about the passive movement of macromolecules across the endothelium as it might relate to the use of polymers for drug delivery. There exist two fundamentally different views of capillary permeability: physical/physiological (when the process is described in terms of pressures, fluxes and mass balance), and cellular (when the transport across the capillary is seen as the consequence of transport processes employed by the endothelial cells themselves) — both are considered here. It is concluded that even when passive transport processes are involved, there appears to be a ‘size window’ of about 30–40 Å for macromolecules that, because of their size cannot pass through the kidneys but will cross the normal endothelium in other organs and tissues. Opportunities for the access of macromolecules to the extravascular space due to changes of the endothelium because of disease, are also discussed.
Photoresponsive systems are widespread in nature, and life processes such as photosynthesis, visi... more Photoresponsive systems are widespread in nature, and life processes such as photosynthesis, vision, phototropism, and phototaxis are linked with structural changes of molecules caused by sunlight. Similar photochemical transformations can be employed to render synthetic agrochemicals and drugs active or to govern their bioavailability at the site of action. Related fundamental physical and chemical processes are discussed as part of the introductory paragraph. In agrochemical applications mainly three different ways have been reported as to how light can be utilized to optimize pesticidal effects in crop protection. The hypersensitization of certain pests to sunlight by chemical compounds represents an effective approach and exists also as a natural mechanism of defense. Photo-removable protective groups and various photoreactive structural moieties have successfully been applied for the rational design of light-activated propesticides. Finally, daylight can function as a triggering and governing factor in controlled-release systems based on photoresponsive polymers. Among the major advantages of light-regulated pesticides, the target-directed activation and the inherent detoxification predominate. In biomedical applications, light has also been used to activate compounds to time their action. Although radiation of various types (microwave, X-ray, and gamma radiation) has been used extensively for both treatment and diagnostics, the limited access of UV and visible light to most tissues of the body prevents its general use as the activating trigger. We review here three areas only: cutaneous photobiology-related applications; photoaffinity labeling; and porphyrins as therapeutic agents.
Abstract Precision medicine initiative is an attempt to improve disease treatment and prevention ... more Abstract Precision medicine initiative is an attempt to improve disease treatment and prevention by taking into account individual variability in genes, environment, and lifestyle for each person. Successful application of new knowledge generated by precision medicine will ultimately require the availability of precision drugs: drugs that act exclusively on disease molecular targets without impacting adversely on the rest of the body. This review examines recent progress to developing such site-specific targeting drug systems. Progress to such a goal has been slow. It is concluded that material science needs to take into full consideration the essential properties and requirements of body physiology. In turn, biology needs to define unique features of disease on which effective drug-delivery systems could be based.
ABSTRACT This contribution summarizes the current knowledge about the passive movement of macromo... more ABSTRACT This contribution summarizes the current knowledge about the passive movement of macromolecules across the endothelium as it might relate to the use of polymers for drug delivery. There exist two fundamentally different views of capillary permeability: physical/physiological (when the process is described in terms of pressures, fluxes and mass balance), and cellular (when the transport across the capillary is seen as the consequence of transport processes employed by the endothelial cells themselves) — both are considered here. It is concluded that even when passive transport processes are involved, there appears to be a ‘size window’ of about 30–40 Å for macromolecules that, because of their size cannot pass through the kidneys but will cross the normal endothelium in other organs and tissues. Opportunities for the access of macromolecules to the extravascular space due to changes of the endothelium because of disease, are also discussed.
Uploads
Papers by Karel Petrak