[Impact of hyperoxia on the phenotype of pulmonary artery smooth muscle cells].

Objective: To investigate the influence of varied oxygen (O2) concentration environments on the phenotypic transformation of pulmonary artery smooth muscle cells (PASMC) and the mechanism of pulmonary hypertension. Methods: Primary rat PASMC were isolated and cultured through the process of enzymatic digestion. Following identification, the stable passaged PASMC were subjected to a 6-hour incubation in sealed containers with normal O2 content (group C) and relative O2 content comprising 55% (group H55), 75% (group H75), and 95% (group H95). mRNA and protein expression of α-Actin (α-SMA), smooth muscle 22α (SM22α), osteopontin (OPN), and matrix metalloproteinase-2 (MMP-2) were measured using real-time quantitative PCR and western blot analysis. Results: The H55 group displayed no significant difference from the C group in terms of mRNA and relative protein expression levels for α-SMA, SM22α, OPN, and MMP-2 (all P>0.05). On the other hand, groups H75 and H95 exhibited a reduction in mRNA and relative protein expression of α-SMA and SM22α, along with an increase in mRNA and relative protein expression of OPN and MMP-2 when compared with both the C and H55 groups (all P<0.05). The H95 group showed a higher relative mRNA expression of MMP-2 as compared to the H75 group (P<0.05). Conclusions: Oxygen concentration environments of 75% or higher can serve as the foundation for the pathogenesis of pulmonary hypertension, essentially by inducing a phenotypic transformation in PASMC towards adopting a robust secretory function. This induction is contingent upon the concentration of oxygen present.

Studies on the energy release of rice mitochondria under different conditions by means of microcalorimetry.

The thermodynamic and kinetic behaviors of energy release of mitochondria isolated from rice (Oryza sative L.) were studied by using a LKB 2277 Bioactivity Monitor under different conditions. The thermogenesis curves of energy release of the rice mitochondria (which had been kept at 0-3 degrees C for 15 h and 40 day before the determination) were determined respectively at 25 and 30 degrees C, and the difference in shape of the thermogenesis curves and thermodynamic and kinetic characteristics were compared. The thermodynamic and kinetic parameters of energy release of the mitochondria in the thermogenesis increasing stage have been calculated, and the experimental thermokinetic equations of the thermogenesis have been established. The results indicated that the lower the temperature, the slower the energy release of the rice mitochondria. Both the thermogenesis and the energy release rate of the rice mitochondria increased after the mitochondria was kept at lower temperature for 40 days. One can use the methods to characterize the ability of the rice mitochondria to release energy under different conditions.

Assay for Laccase activity by microcalorimetry: laccase was extracted from china lacquer of Rhus vernicifera.

The reactions between Laccase (extracted from China lacquer of Rhus vernicifera) and various substrates (3,4-Dihydroxybenzaldehyde, Guaiacol, Pyrogallol, Gallic acid) have been studied using LKB-2107 batch microcalorimetry system. Based on calorimetry, a new method has been proposed. Laccase activity and the Michaelis constant K(m) have been determined simultaneously by this method. The method is simple, sample-saving, and valid for a wider range of substrate concentrations. Furthermore, it can be extended for assaying other enzymes catalyzing reactions using this method.

Determination of the thermogenesis curves and studies of the thermodynamics and thermokinetics of seed germination.

The thermogenesis curves of the germination of different rice and tree seeds were determined and studied by using a newly constructed microcalorimeter. The thermogenesis curves of the germination of the seeds demonstrate the existence of physiological triphasic patterns, which include imbibition, activation and growth stages in the germination process. The thermodynamics and thermokinetics of the main growth phase of the growth stage in the germination process have been studied. The growth heat effect (deltaH), the growth rate constant (k), the growth inhibitory factor (s) and deceleration rate constant (beta) have been determined and calculated, In addition, the experimental thermokinetic equations of the growth stage in the seed germination process have been established.

Microcalorimetric study of metabolic inhibition by humic acids in mitochondria from Oryctolagus cuniculus domestica liver cells.

The metabolic thermogenesis curves of mitochondria isolated from Oryctolagus cuniculus domestica liver tissue have been determined by using an LKB-2277 bioactivity monitor. After isolation, mitochondria maintain activity when stored in appropriate nutrients. The thermokinetic equation: [formula: see text] was established for the activity recovery phase of metabolism. For these studies, the order of metabolism was found to be zero. The metabolic activity of mitochondria was inhibited by humic acid, a potential toxicant in Kashin-Beck and Keshan diseases. Experimental results indicate that humic acid will effect the heat output and lag time of mitochondrial metabolism.

Microcalorimetric study of mitochondria isolated from fish liver tissue.

We determined the thermogenesis curves of mitochondria isolated from fish liver tissue by using an LKB 2277 Bioactivity Monitor. After isolation from the fish liver, mitochondria still have activity and can live for a long time by using the stored nutrients. We calculated the recovery rate constants of mitochondria. We found that the thermogenesis curves of mitochondria are similar to those obtained from prokaryotic cells, but not similar to those obtained from eukaryotic cells. We determined the metabolic thermogenesis curves of mitochondria isolated from two kinds of carp liver tissue, scattered-scaled mirror carp and harvest carp. There are some important similarities and some important differences between these thermogenesis curves.

[Determination of thermograms of bacterial growth].

The fundamental growth thermograms of bacteria have been determined by using the microcalorimetric method. These perfect thermogram curves reflect the changes of bacterial growth patterns (including the lag phase of growth, log growth, stationary phase and the decline phase of growth). In our experiments, highly characteristic and reproducible growth patterns are observed under the same condition, therefore one can use these thermograms as "finger print" to discriminate bacteria. On the other hand, there thermogram curves contain ample information, which are very significant for the studies on microorganism metabolism, bio-thermokinetic and clinical fields.