Oxygenation and Lung Morphology in a Rabbit Pediatric ARDS- Model under High Peak Pressure Ventilation plus Nitric Oxide and Surfactant Compared with Veno-venous ECMO

The aim of the study is to investigate which of two treatment options of saline lavage induced ARDS in rabbits is better in terms of oxygenation and prevention of barotrauma: combined high peak pressure ventilation with surfactant administration and inhaled nitric oxide or veno-venous ECMO combined with low peak inspiratory pressure ventilation.

Materials and Methods

After saline lavage (10 cc/kg repeated as long as foamy retrieval was observed) two combined therapeutic strategies were examined: ventilation with high inspiratory pressures (35 cm H2O) with additional exogenous surfactant administration (100 mg/kg) and inhaled nitric oxide (10 PPM) (n=5, group 1) and low inspiratory pressure (20 cm H2O) ventilation under veno-venous ECMO support (n=5, group 2). The FiO2 was maintained at 1.0 in both groups. The paO2/FiO2 ratio was calculated in 30 minute intervals for 4 hours. After that the animals were sacrificed and the lungs examined macro- and microscopically. Aeration was described in a semiquantitative method using the alveolar expansion index. Oxygenation in group 1 was significantly better than in group 2, it increased significantly after surfactant but not after additional nitric oxide administration. However, the lungs in group 1 showed severe signs of baro/ergotrauma (Hyaline membranes, air leaks, infiltration of polymorphonuclear (PMN) granulocytes and macrophages, break down of alveolar capillary membranes) after 4 hrs of combined therapy, whereas the lungs in group 2 appeared normal. Adding surfactant and NO to a high tidal volume ventilation improved oxygenation, but did not prevent baro/ergotrauma. Ventilation with low inspiratory pressures combined with ECMO caused little baro/ergotrauma but adequate oxygenation could not be achieved, probably due to anatomical features of the rabbit which do not allow appropriate blood flow within the ECMO-circuit.

Expression of p190A during apoptosis in the regressing rat ventral prostate

After hormonal ablation, 90% of the secretory epithelial cells of the prostate undergo apoptosis, and the remaining cells are reorganized as the tissue is remodeled. Using differential display RT-PCR of total RNA extracted from the rat ventral prostate before and 4 days after castration, we have cloned and sequenced a number of complementary DNAs whose cognate messenger RNAs (mRNAs) may be either up- or down-regulated during prostatic regression. One sequence of particular interest, 25.2, is up-regulated after castration and is homologous to p190, a protein associated with cytoskeletal reorganization. RT-PCR has confirmed that the steady state level of p190A mRNA is increased in the rat ventral prostate after castration, and Western blot analysis indicates that the protein levels for p190A also increase. The steady state level of p190B mRNA, the second isoform of p190, does not appear to change significantly after hormone ablation. Immunohistochemical analysis demonstrates that p190A is up-regulated primarily in the columnar epithelial cells that actively undergo cell death after hormone ablation. As Rho-GAP signaling had been shown to be influenced by p190 levels, leading to the disassembly of focal adhesion contacts and the loss of cytoskeletal architecture, we also measured the changes in Rho-GAP during prostate regression. Rho-GAP levels do not change significantly, suggesting that changes in stoichiometry of the interaction between p190A and Rho-GAP may be a prerequisite for the initiation of cytoplasmic condensation. These intracellular events coupled with the proteolytic degradation of the extracellular matrix appear to be integral to the apoptotic process in glandular epithelia.

Amino acid sequence of the K-peptide generated by limited proteolysis of glucose dehydrogenase from Bacillus megaterium by proteinase K1

Proteolysis of glucose dehydrogenase from Bacillus megaterium with proteinase K apparently generated two fragments. The small fragment, designated as K-peptide, was sequenced and its covalent structure was determined as Ser-Ser-Glu-Ala-Ser-Tyr-Val-Thr-Gly-Ile-Thr-Leu-Phe-Ala-Asp-Gly-Gly-Met-Thr- Gln-Tyr-Pro-Ser-Phe-Glu-Ala-Gly-Arg-Gly. The sequence analysis showed that the K-peptide consists of two identical fragments, one of which is lacking one serine residue at the amino-terminus.

Limited proteolysis of glucose dehydrogenase from Bacillus megaterium by proteinase K

Glucose dehydrogenase from B. megaterium is subjected to proteolysis with proteinase K. Upon proteolysis the enzyme is inactivated and the polypeptide chain is cleaved into two distinct fragments. These components designated as K-protein and K-peptide have molecular masses of 26 000 and 3 000 Da, respectively. Under native conditions the K-protein and K-peptide remain associated and the tetrameric structure of the proteolytically modified enzyme is preserved. The K-protein and K-peptide were isolated and characterised. The cleavage occurs in the C-terminal region of the polypeptide chain. -Leu Ala decreases Ser-Ser-Glu is proposed as the cleavage site.