Dagys, Arvydas

Objective: To determine the activity of aspartate aminotransferase (AST) in the pulp of orthodontically intruded teeth and to test the sensitivity of these teeth by means of electrical pulp testing (EPT). Materials and Methods: The study sample consisted of 21 healthy subjects who needed extraction of first premolars for orthodontic reasons. In every subject, one premolar included in a 0.016 – 0.022 stainless steel spring from the first molar and loaded by the force was regarded as a test tooth. The magnitude of the intrusive tipping force for every tooth was calculated with the use of ANSYS 10.0 software. The contralateral premolar was used as a control tooth. After 7 days, the spring was removed, and EPT was applied to test and control teeth. The teeth were extracted, and the dental pulp was removed. AST activity in the pulp was determined spectrophotometrically at 20 C. Results: Estimated mean AST activity values ranged from 0.572 0.097 U/mg in the test teeth to 0.348 0.053 U/mg in the control teeth (P .01). The EPT test showed significant differences between test and control teeth (P .001). The mean estimated magnitude of the intrusive tipping force was 61 4.5 g. Conclusion: Seven days of orthodontic intrusion can cause metabolic changes in the pulp expressed by increased AST activity. The increased threshold in the pulp reaction to EPT indicates changes in the neural response of the pulp.

AIM: Orthodontic tooth movement can affect the viability of the dental pulp. The aim of this study was to determine the activity of aspartate aminotransferase (AST) in the pulp of orthodontically intruded teeth and the responses of same teeth to electrical pulp testing (EPT). SUBJECTS AND METHOD: Twenty-one healthy subjects (mean age 15.5 ± 0.5 years, range 11–21 years) who needed fi rst premolar extractions for orthodontic reasons. One randomly chosen premolar, included in a 0.016 × 022 inch stainless steel spring from the fi rst molar and supported by the force, was considered as the test tooth. The magnitude of the intrusive tipping force for every tooth was calculated using the ‘Loop’ software program. The contralateral premolar was not subjected to mechanical stress and was used as the control. After one week of intrusion, the spring was removed, and EPT was applied to both test and control teeth. The teeth were then extracted and the dental pulp removed from both teeth. AST activity was determined spectrophotometrically at 20ºC. The SPSS program was used for data analysis. RESULTS: AST activity was 0.572 ± 0.097 U/mg of pulp tissue (range 0.14-1.90 U/mg) in the test teeth, and 0.348 ± 0.053 U/mg (range 0.07-1.00 U/mg) in the control teeth (P < 0.01). The 95 per cent confi dence interval (CI) of the differences in mean values of AST activity of the groups was 0.069 to 0.379 U/mg of pulp tissue. EPT testing showed signifi cant difference between the test (26.95 ± 3.91 μA) and control (7.76 ± 1.41 μA) teeth (P < 0.001). The 95 per cent CI of the differences of the mean values of the EPT response of the groups was 12,902 to 25,479 μA. The magnitude of intrusive tipping force was 61 ± 4.5 g (range 34-106 g). Pearson correlation coeffi cient showed a non-signifi cant straight-line relationship between the patient’s age, root number, pulp weight, EPT response and force magnit [...].

Our previous studies on saponin-permeabilized rat heart muscle fibers revealed that fatty acid (FA) oxidation induces a dramatic increase of the outer mitochondrial membrane (OMM) permeability for ADP. The aim of this study was further elucidation ofthe role of FA in the regulation of oxidative phosphorylation in rat heart muscle fibers. Oxidation of octanoyl-L-carnitine, decanoic acid (in combination with pyruvate+malate (PM)) and oleoyl-CoA+L-carnitine decreased app. KmADP up to 76 ± 1 mM, 66.0 ± 13 mM and 55.7 ± 5 mM, respectively, as compared to this value characteristic for PM (217 ± 4 mM). Thus, saturated (long and medium chain), unsaturated, activated or not activated FA produce the similar effect. Furthermore, we showed that even low concentration (2 mM) of palmitoyl-L-carnitine (PC) caused the large decrease in the app. KmADP (up to 108 ± 17 mM compared to 243 ± 19 mM for PM). The low app. Km value was also observed (59 ± 26 mM) when PC oxidation was titrated with exogenous ATP. Thus, the effect of FA did not depend on the way of delivery of ADP to mitochondria (exogenous, or endogenous - produced by ATP-ases of the cell). The low app. KmADP value observed in case of palmitoyl- or octanoyl-L-carnitine oxidation increased more than 3 times in medium supplemented with 5% dextran T-70. However, the oncotic pressure had no effect on high KmADP value characteristic for PM. Noteworthy, dextran diminished (by 21-25%) the State 3 respiration rate with all three substrates. We also demonstrated that the functional coupling between ADP/ATP translocator and creatine kinase is preserved in mitochondria despite the significant increase in the OMM permeability for ADP induced by FA oxidation. The findings that FA oxidation reduces app. KmADP and, thus, increases OMM permeability for ADP was also confirmed on human cardiac fibers.

Nustatyta, kad oksiduojant riebalų rūgštis (palmitoil-L-karnitiną ir oktanoil-L-karnitiną) mišinyje su piruvatu ir malatu, trigubai sumažėja tariamoji K m ADP reikšmė, kuri būdinga saponinu permeabilizuotų žiurkės miokardo skaidulų mitochondrijoms, oksiduojančioms tik piruvatą ir malatą. Pažymėtina, kad ryškus mitochondrijų išorinės membranos pralaidumo ADP padidėjimas (K m ADP sumažėjimas) stebimas jau esant mažai (2,2 μM) palmitoil-L-karnitino koncentracijai. 5% dekstrano T-70 pridėjimas į terpę tris kartus padidino žemą (77 μM K m ADP reikšmę, būdingą oktanoil-L-karnitino oksidacijai. Nors šio reiškinio mechanizmas nėra aiškus, mitochondrijų morfologiniai pakitimai yra svarbūs.

The aim of the present study was to get more insight nto the mechanism(s) of action of agaric acid (AA), the known inhibitor of the adenine nucleotide translocase (ANT), on the mitochondrial oxidative phosphorylation system. It has been shown that AA competitively inhibits ANT and ADP-stimulated respiration of rat liver mitochondria with succinate in hypotonic sucrose medium but has no effect on the State 4 and State 3- uncoupled respiration (Chavez and Klapp, 1975]. [...].