The General Hospital Corporation

Allan Oseroff

John A Parrish

Louis Cincotta

James Foley

Martin Prince

A method of ablating atherosclerotic plaque by means of short-duration laser light pulses. A carotenoid, such as beta-carotene, is preferably administered to the patient by injection or ingestion prior to exposing the plaque with laser light. Research data obtained by analysis of the absorption characteristics of plaque and the healthy arterial tissue reveals that the plaque may be selectively ablated without damaging the surrounding normal tissue by illuminating the plaque with laser light having a wavelength of about 430 to about 510 nanometers such that the relative absorption coefficient exhibited by the plaque is more than 1.5 times the absorption coefficient of the arterial tissue. Short duration laser light pulses preferably illuminate the plaque for less than the thermal relaxation time of the volume of exposed material. The intensity of the laser light is preferably in the range from about 1 to about 9 joules/cm.sup.2 in order to ablate the plaque without endangering the surrounding tissue. The carotenoid administered to the patient enhances the absorption coefficient of the plaque to facilitate ablation and additionally facilitates the detection of the plaque.

Laser-induced ablation of atherosclerotic plaque

A method of killing carcinoma cells associated normal cells using light of a predetermined wavelength. The method includes contacting the cells with a chromophor at a given concentration. The chromophor is positively charged and sufficiently lipophilic to be taken up by the mitochondria of the carcinoma cells and is retained substantially longer in the mitochondria of carcinoma cells than in normal cell mitochondria; or it may be taken up in greater quantity by the carcinoma cells than by the normal cells. The chromophor must also have a therapeutic index for light-induced cell killing of at least 500 for light of the predetermined wavelength, and has a therapeutic ratio for light-induced killing of at least 50 for light of said pre-determined wavelength. The cells are then exposed to light of this wavelength.

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Brookline, MA, United States of America

Allan Oseroff