[Measurement of biological tissue destruction time after exposure to eximer XeCl laser]. / Izmerenie vremeni razrusheniia biotkani pri deistvii izlucheniia éksimernogo XeCl-lazera.

Relationship between atherosclerotic patch destruction time under UV light from a XeCl laser and energy density of 1.3-4.7 J/cm2 has been studied experimentally. As energy density increased, the destruction time, estimated on the basis of exploring product release by continuous-wave He-Ne laser, decrease from 40 to 3.5 microseconds.

[Thrombogenic properties of the inner vascular surface following laser exposure]. / Trombogennye svoistva vnutrennei poverkhnosti sosuda posle lazernogovozdeistviia.

Laser angioplasty, using YAG-neodymium laser and a balloon catheter with monofiber quartz light guide (400 micron), introduced into its central canal, was performed in 8 dogs with thromboses of 11 femoral or carotid arteries. Average energy expenditure for recanalization was 26 +/- 4 J, with 4.9 +/- 0.3 W and exposure time of 5.1 +/- 0.7 s. Re-thrombosis developed after 5 to 10 days in all arteries, left in the circulation network after laser angioplasty. The latter part of the study is dealing with the assessment of the surface of femoral or carotid arteries of the dogs after laser exposure. This was done by quantitation of the adhered platelets after platelet-enriched plasma was circulated through vessels, whose inner surface was 1) intact, 2) de-endothelized, or 3) laser-damaged, using a scanning electron microscope. The thrombogenic index was 65-96, 85 and 66%, respectively, for the YAG-neodymium, argon and eximeric (XeCl) lasers.

Comparison of different lasers in terms of thrombogenicity of the laser-treated vascular wall.

The thrombogenic properties of the laser-treated vascular wall are reported as quantitatively assessed on the basis of 33 experiments with peripheral canine vessel segments. Three types of surfaces, namely, 1) intact, 2) mechanically de-endothelized, and 3) postlaser, have been simultaneously exposed to platelet-enriched plasma in a sequentially organized artificial circulation system. Then the adherent platelets have been counted on the treated surfaces, and the relative thrombogenicity index has been calculated according to the equation T = (A1 - Aint)/(Ad - Aint), where Aint, Ad, A1 = the adherent platelet counts on intact, mechanically de-endothelized, and laser-treated surfaces, respectively. The following lasers have been evaluated: 1) Nd-YAG, 1,060 nm, continuous wave, 4W; 2) argon-ion, 480 and 514 nm and argon-ion, 350 nm, continuous-wave, 1 W and 400 mW [corrected], respectively; 3) excimer XeCl, 308 nm, pulsed, 30 mJ per pulse, repetition rate 10 Hz [corrected]; and also 4) the laser-heated metal probe (2 mm diameter, Trimedyne, Nd-YAG) 1,060 nm, 8 W. The thrombogenicity index values obtained were 83 +/- 7, 72 +/- 8, 57 +/- 9, 63 +/- 7, and 82 +/- 9%, respectively. The differences between these values were statistically insignificant. The data are suggestive of the essential requirement of, at least, anticoagulant therapy after laser angioplasty irrespective of the laser type.

[Comparison of the thrombogenic properties of vascular wall after exposure to different lasers]. / Sravnenie trombogennykh svoistv sosudistoi stenki posle deistviia razlichnykh lazerov.

Quantitative thrombogenic assessment of the inner arterial surface after laser exposure was made in 33 experiments with peripheral arterial strips of dogs. In one experiment, vascular strips with native, mechanically de-endotheliazed or laser-damaged surface were consecutively placed in a platelet-enriched plasma recirculation system, after which platelet adhesion was estimated on vascular surface of the three types, using a scanning electron microscope, and the relative thrombogenic index was calculated. The laser models used included: 1) the AIG-neodymium model, 1.06 micron; 2) the argon model with visible (488 and 514 nm) and ultraviolet (350 nm) spectra; 3) the XeCl excimer type, 308 nm, as well as a preheated metal rod, imitating a ceramic or metal tip of the light guide outlet. The thrombogenic index was 83 +/- 7; 72 +/- 8; 57 +/- 9; 63 +/- 7 and 82 +/- 9%, respectively, for the above types of exposure, the differences being virtually insignificant. It is suggested that, irrespective of the type of laser employed, laser angioplasty should at least be accompanied with intensive anticoagulant therapy.

[Lethal and mutagenic effect of the XeCl laser on Escherichia coli]. / Letal'noe i mutagennoe deistvie izlucheniia XeCl lazera na bakterii Escherichia coli.

The survival rate and reversions to tryptophan-independence of Escherichia coli after XeCl laser irradiation (lambda = 308 nm) within the dose range from 10(3) to 10(5) J/m2 have been studied to show that LD37 is 10(4) J/m2, the survival rate at a maximum dose of 10(5)J/m2 is 1 per cent, and the number of mutants per 10(6) cells survived is 100.