PubMed Health⌕ Search

Biomedical subjects

G Wettermark

Publications and source records attributed to G Wettermark.

14 recordsLinked to original sources
PubMed1991

Analytical applications of bioluminescence--a matter of proper kinetic design and recording.

The way bioluminescence analysis employs photometric technique is illustrated in relation to the resulting demands on signal processing and detectability. The analytical reaction may be regarded as composed of a supply reaction providing the excited species followed by a decay reaction in which light is emitted. Bioluminescence analysis implies the recording of a velocity, hence rate regulation forms the basis of the development of an analytical set-up. In principle two means of design are used, either the application of a pulse technique or the monitoring of a durable emission. Both methods have their respective pros and cons but operating in the intermediate time range is sometimes favorable. The pulse technique is an arrangement where the entire emission develops out during a limited amount of time usually as a flash of light in the subminute range. It is accompanied by demands for rapid mixing and initiation of the analytical process as well as fast recording techniques. Durable emission measurements are based on a slowing down of the process, e.g., by reducing the concentration of enzyme or by the addition of inhibitors, so that the light intensity may be regarded as constant during the measurements. This facilitates the measuring procedure and provides for simplified handling, but occurs at a cost of emission intensity and sensitivity. Bioluminescence analysis mimics metabolic routes yielding great possibilities for coupling with other metabolic pathways. Such coupled systems are suited for analysis of a wide variety of metabolites and enzymes. By proper kinetic design it is possible to make the analyses largely insensitive to variations in activity of the reagents.

Animals↗
PubMed1989

Design of coupled reactions for simplification of bioluminescence analysis.

Luminescence analysis may be applied to many substances by arranging a prior reaction producing a species entering the light-emitting reaction. Under favourable conditions the two consecutive reactions are carried out simultaneously as a one-step procedure. In a bioluminescence assay, luciferase stability is frequently a problem, making it desirable to develop analytical schemes where the analytical response becomes largely independent of any impaired luciferase activity. The value of maximal emission or an approached steady-state level is a convenient and usually well-defined analytical parameter. When recording this level it is important to design the participating reactions in a way that compensates for changes in luciferase activity.

Chemical Phenomena↗
PubMed1985

ATP-content in muscular interstitial fluid during pulsatile and non-pulsatile cardiopulmonary bypass in pigs.

The potential benefit of pulsatile flow during cardiopulmonary bypass (CPB) has been discussed extensively, but the debate is still unsettled. Release of intracellular ATP is a useful indicator of cellular damage; we have measured the ATP content in perfusates from muscles in pigs undergoing pulsatile or non-pulsatile CPB for 100 min at 37 degrees C. In 5 pigs the Polystan Pulsatile Pump was used and in 5 pigs a conventional roller pump. 11 pigs served as controls; 6 received heparin like the animals subjected to CPB, whereas the remaining 5 animals were not heparinized. ATP was measured by the firefly luminescence technique. At the start of the CPB or control period the ATP content was very low in all 4 groups. In the non-heparinized controls ATP continued to decrease, whereas in the other 3 groups ATP increased linearly during the 100 min of CPB or control period. It is concluded that, by this method, there was no significant difference between pulsatile and non-pulsatile CPB regarding damage to vascular endothelial or smooth muscle cells. However, heparinization per se caused a marked leakage of blood cells into the extravascular space even after the initial leakage from the cannulation had disappeared. This leakage was enhanced by non-pulsatile but not by pulsatile CPB.

Adenosine Triphosphate↗
PubMed1984

ATP release from pig muscles during exercise measured by the firefly luminescence technique.

ATP measurements were performed on perfusates from muscles in anaesthetized pigs in vivo. Samples were obtained every 5 min by perfusion of a double-walled, fenestrated cannula inserted in the muscle. Five pigs served as controls and in 6 animals the adductor muscles of the thigh were electrically stimulated to contract each second for a period of 30 min. ATP was measured by the firefly bioluminescence technique. Immediately after insertion of the cannula ATP was high in the perfusate probably due to the physical damage to the cells and capillaries. After 50 min ATP reached a rather low level. Compared to controls, ATP in centrifuged, cell-free perfusate was unchanged during 30 min of muscle activity and for 60 min thereafter. In cell-containing samples ATP was slightly increased during the muscle activity period, probably due to damage from the cannula. It was concluded that, by this method, no indication was found of an association of muscular activity and release of ATP into the extracellular space.

Adenosine Triphosphate↗
PubMed1977

Toxic effects of 8-methoxypsoralen on lymphocyte division.

Cultured human leucocytes have been used to examine the toxicity and phototoxicity of 8-methoxy psoralen (8-MOP). It has been shown that 8-MOP depresses cell turnover at concentrations of 10(-10) M or above. In black light (UVA), 8-MOP inhibition begins at concentrations of 10(-14) M. Patients treated for psoriasis with 8-MOP show concentrations of 10(-6)-10(-7) M. The inhibition of cell turnover observed with the present technique is at this concentration 40% for 8-MOP alone and 70% for 8-MOP and black light. These results can be related to the micronuclei and chromosome abnormalities seen in dividing cells.

Cell Division↗
PubMed1977

Chemiluminescence microanalysis of substrates and enzymes.

Extracts from bioluminescent organisms are increasingly used for analysis of small amounts of substrates and enzymes. The light emission is in some organisms related to the conversion of substrates and cofactors of central metabolic importance. Extracts from such organisms are particularly valuable for analytical applications. This is quite obvious in the firefly where the energy, required for light production, is derived from ATP and in a couple of strains of luminescent bacteria where reduced pyridine nucleotides through reduction of flavine mononucleotide is utilized in the light reaction. It deserved to be noted that many biochemical reactions can be coupled more or less directly to the conversion of ATP, NAD(H), NADP(H) and FMN(H), thus providing the basis for a great variety of analyses. Special kinds of bioluminescent reactions are also of considerable interest, as for instance the relationship between "active sulphate" and PAP, which participate in the formation of light in the sea pansy (Renilla reniformis). High sensitivities are often reached in chemiluminescence analysis making the technique suitable for samples composed of a small number of cells. How bioluminescence has been employed in these kinds of microanalyses is examplified in studies of nucleotides, metabolites and enzymes with low activities.

Adenosine Triphosphate↗
PubMed1977

Photodynamic inactivation of verrucae vulgares. I.

Verrucae vulgares (v.v.) stained in vivo and in vitro with 0.1% and 1% proflavine in 100% dimethylsulphoxide (DMSO) and 0.1% and 1% neutral red in 100% DMSO were examined grossly and by fluorescence microscopy. Light transmission studies were made using both whole v.v. embedded in methacrylate and 5 micrometer frozen sections. The dyes were seen to penetrate to the epidermal and dermal structures in the in vivo stained v.v. and accumulate in the cell nuclei. The average concentration of neutral red in the v.v. was estimated to be 2 X 10(-5) M. The concentration of proflavine was lower than that, but exceeded 10(-6)M. There was diffuse staining throughout the in vitro stained warts. From 400-600 nm the warts were penetrated by at least 1% of the light directed toward their surfaces.

Acridines↗
PubMed1977

Photodynamic inactivation of verrucae vulgares. II.

Photodynamic inactivation therapy, consisting of a double-blind, paired comparison treatment schedule, was used in treating 56 patients for recalcitrant, symmetrical verrucae vulgares. 0.1% proflavine in 100% dimethylsulphoxide (DMSO) and 0.1% neutral red in 100% DMSO were used as active dyes, and 1% picric acid in 100% DMSO and 1% color ruber in 100% DMSO and 1% color ruber in 100% DMSO served as corresponding placebos. A Westinghouse sunlamp and black light were used to irradiate the warts dyed with proflavine and its placebo, and the warts dyed with neutral red and its placebo were irradiated with an ordinary light bulb (Osram 588597). 50 patients completed the treatment. 10 of the 27 patients treated with proflavine and 10 of the 23 patients treated with neutral red were cured by the end of an 8 week period, with the warts disappearing simultaneously from the actively as well as the placebo-treated side. Complement fixing antibodies against wart virus were detected in one of the cured patients and 2 who were treatment failures.

Acridines↗
PubMed1975

Bioluminescence assay of enzymes obtained from buccal epithelium by superficial scraping.

A method is presented for the simultaneous assay of buccal enzymes by measuring reduced nicotinamide adenine dinucleotide and adenosine triphosphate with the aid of the bioluminescence of luciferase extracts. The activity of glucose-6-phosphate dehydrogenase (G6PDH) was shown earlier to be increased in homogeneous leukoplakias of the oral mucosa. Since smoking has been implicated as an etiologic factor of leukoplakia, G6PDH was measured in the normal buccal epithelium of cigarette smokers. No difference was found in the activity of G6PDH between smokers and nonsmokers when related to the activity of pyruvate kinase, which is known to be invariable in healthy and leukoplakic oral mucosa. A new compact kinetic luminescence analyzer is briefly described.

Adenosine Triphosphate↗