Changes in the urine volatile metabolome throughout growth of transplanted hepatocarcinoma.

Trained detection dogs distinguish between urine samples from healthy organisms and organisms with malignant tumors, suggesting that the volatile urine metabolome contains information about tumor progression. The aim of this study was to determine whether the stage of tumor growth affects the chemical differences in the urine of mice and to what extent the "olfactory image of disease" perceived by dogs coincides with the "image of disease" recorded by the mass spectrometer. We used a novel laser ionization mass spectrometry method and propose a mass spectrometric analysis without detailed interpretation of the spectrum of volatile metabolomes in urine. The mass spectrometer we use works without sample preparation and registers volatile organic compounds in air at room temperature without changing the pH of the sample, i.e. under conditions similar to those in which dogs solve the same problem. The experimental cancer models were male BDF-f1 hybrid mice transplanted with hepatocarcinoma tissue, and similar mice transplanted with healthy liver tissue were used as controls. Our data show that both dogs and our proposed laser mass spectrometry method are able to detect both the entire spectrum of volatile organic compounds associated with the disease and minor changes in this spectrum during its course.

Biocompatibility of Laser-deposited Hydroxyapatite Coatings on Titanium and Polymer Implant Materials.

We have investigated the biocompatibility of calcium phosphate coatings deposited by pulsed laser ablation from hydroxyapatite (HA) targets onto polyethylene and Teflon substrates. It was found that the cell density, attachment, and morphology of primary rat calvaria osteoblasts were influenced by both the original polymer and by the nature of the apatite coatings. HA coatings on Teflon were found to have higher biocompatibility in terms of cell adhesion and spreading. In vivo studies of bone response to coatings deposited by KrF excimer and CO2 lasers on commercial Ti6A14V alloy implants show that both deposition techniques suppress fibrous tissue formation and promote osteogenesis. © 1998 Society of Photo-Optical Instrumentation Engineers.

[Biocompatible coatings for metallic implants obtained by laser spraying]. / Biosovmestimye pokrytiia dlia metallicheskikh implantov, poluchennye lazernym napyleniem.

Use of various lasers and regimens for spraying the coatings and for additional thermal processing makes it possible to purposefully alter the morphology, composition, and crystallinity of the coatings, and hence, the optimal coatings, as regards their biological activity, may be created. Replacement of eximer lasers with CO2 lasers makes the spraying process cheaper and comparable in efficacy with the plasma process, with the quality of coatings and reproducibility of their parameters appreciably improved. Experiments with coatings of three types, sprayed by CO2 lasers, demonstrated that they met the mechanical and physico-chemical requirements of biocompatibility.

[The structural characteristics of the bony tissue at the surface of an implant with hydroxyapatite spray-coated with excimer and CO2 lasers]. / Osobennosti postroeniia kostnoi tkani u poverkhnosti implanta s pokrytiiami iz gidroksiapatita, napylennymi éksimernym i CO2-lazerami.

Rat experiments were performed to study osteogenesis and osseointegration in implanting fragments of dental titanic implants into the spongy bone. The implant spray-coating with hydroxyapatite produced by excimer and CO2 lasers stimulates osteogenesis. Bone tissue integration with implant proceeds more actively in response to CO2 laser radiation. The weakest integration was registered between the metal and bone tissues.