Effect of conventional mechanical ventilation and jet ventilation on airway pressure in dogs and plastic models with tracheal stenosis.

OBJECTIVE: To evaluate the effect of jet ventilation on tracheal stenosis in dogs and plastic models. DESIGN: Prospective, randomized trial in dogs, and multitrial tests in tracheal stenosis models. SETTING: Animal laboratory in a university setting. INTERVENTIONS: Tracheal stenosis was surgically created around the middle of the trachea. Conventional mechanical ventilation and jet ventilation were compared at the same value of Paco2 in dogs and at the same tidal volume in tracheal stenosis models. SUBJECTS: Twelve mongrel dogs and four types of plastic models with combinations of short or long stenosis and fluid or nonfluid stenosis. MEASUREMENTS AND MAIN RESULTS: Canine Studies. Mean peak peak airway pressure values at the distal and proximal portion of the stenosis, and the end-expiratory pressure at the distal portion of the stenosis, were significantly higher during conventional mechanical ventilation than during jet ventilation. The mean values of arterial pressure, pulmonary arterial pressure, central venous pressure, and cardiac output did not change significantly between conventional mechanical ventilation and jet ventilation, except for the pulmonary artery occlusion pressure valve. Plastic Mold Studies. peak airway pressure and end-expiratory airway pressure at the poststenotic trachea during jet ventilation with the model lung were significantly lower than during conventional mechanical ventilation. The difference in peak airway pressure, and end-expiratory airway pressure values between jet ventilation and conventional mechanical ventilation increased more in short stenosis and nonfluid stenosis. CONCLUSIONS: The jet flow that struck the portion of the stenosed wall reversed direction, even during early expiration. Therefore, the expiration during jet ventilation was facilitated more by the reversed flow than by the expiration during conventional mechanical ventilation. This reversed flow may provide lower end-expiratory airway pressure at the poststenotic portion with jet ventilation than with conventional mechanical ventilation. We conclude that jet ventilation was a useful method of ventilation in cases with tracheal stenosis, especially nonfluid and short stenosis.

DNA base and deoxyribose modification by the carbon-centered radical generated from 4-(hydroxymethyl)benzenediazonium salt, a carcinogen in mushroom.

Modification of the base and the sugar moieties of DNA with 4-(hydroxymethyl)benzenediazonium salt (HMBD), a carcinogen in the mushroom Agaricus bisporus, was investigated. When deoxyribonucleosides dGuo, dAdo, dThd, and dCyd were incubated with HMBD at pH 7.4 and 37 degrees C, the levels of all the nucleosides were decreased. The decrease was inhibited by ethanol or Cys. When deoxyribose was incubated with HMBD, malonaldehyde was released as assessed by the thiobarbituric acid reactivity. The release was inhibited by ethanol. Major products of the reaction of dGuo and dAdo with HMBD were isolated, and their structures were established to be 8-[4-(hydroxymethyl)phenyl]dGuo (8-HMP-dGuo) and 8-[4-(hydroxymethyl)phenyl]dAdo), respectively. Calf thymus DNA treated with HMBD was enzymatically digested into nucleosides, in which 8-HMP-dGuo and 8-HMP-dAdo were detected. Formation of the modified nucleosides in DNA was inhibited by ethanol or 2-mercaptoethanol. Malonaldehyde was released from DNA treated with HMBD, which indicated that the deoxyribose moiety of DNA had been damaged. The results indicate that the 4-(hydroxymethyl)phenyl radical generated from HMBD can directly modify the base and the sugar moieties of DNA under the mild conditions. Inhibitory effect of ethanol was ascribable to its scavenging activity for the carbon-centered radical. The inhibitory effect of Cys and 2-mercaptoethanol was found to be due to the formation of the reversible adducts between HMBD and the SH compounds.

[Factors influencing delayed type graft-versus-host disease after allogeneic bone marrow transplantation].

Effects of the number of transplanted bone marrow cells and splenectomy performed before the transplantation on delayed type graft-versus-host disease (GVHD) were investigated in mice. The relation between delayed type GVHD and suppressor cells was also studied. Bone marrow cells (1 x 10(5)-1 x 10(7) cells) from CBA/N mice were transplanted to lethally irradiated (10 Gy) C57BL/6 mice, and the same type of transplantation was performed in other mice that underwent splenectomy. Suppressive effects of spleen cells from chimera mouse were measured by the percentage of suppression against alloantigen specific mixed lymphocyte reaction (MLR). The survival rate decreased with the number of grafted cells. However, survival rate was high in the splenectomy group even when the number of grafted cells was small. The incidence of delayed type GVHD was 0% in the 1 x 10(7) cell transplanted group, but that was more than 50% in the 1 x 10(5) cell transplanted group. There was no significant difference in the incidence of delayed type GVHD between the splenectomy group and non-splenectomy group. Spleen cells from chimera mouse without delayed type GVHD had greater suppressive effect against MLR than those with GVHD. These results suggest that alloantigen specific suppressor cells in the spleen of chimera mice inhibit delayed type GVHD.

Bone marrow from cadaver donors for transplantation.

To determine the feasibility of obtaining bone marrow cells from cadaver donors for transplantation, marrow cells were prepared from 17 cadaver donors. After surgical removal of the iliac crest, as many as 2 X 10(9) cells were isolated. Cadaver marrow had a lower percentage of T cells (mean of 10%) than did marrow from living donors. The T cells were lysed by a monoclonal antibody and human complement to a point at which no sheep red blood cell-rosetting cells were detected. Low levels of T colonies, however, grew out from the monoclonal antibody-treated cells. Although cell loss inevitably occurs from purification, antibody treatment, freezing, and thawing, sufficient numbers can be recovered for transplantation. The yield of stem cells was 84% for CFU-C, 39% for CFU-E, 81% for BFU-E, and 48% for CFU-GEMM. We suggest that T cell-depleted marrow cells from cadaver donors could be used for transplantation. Improved immunosuppressive therapy may be required, however, to prevent graft rejection of allogeneic marrow that may have minor histocompatibility differences.