Long-term functional duration of immune responses to HCV NS3/4A induced by DNA vaccination.

We have investigated the ability of hepatitis C virus non-structural (NS) 3/4A-DNA-based vaccines to activate long-term cell-mediated immune responses in mice. Wild-type and synthetic codon optimized (co) NS3/4A DNA vaccines have previously been shown to be immunogenic in mice, rabbits and humans, although we have very poor knowledge about the longevity of the immune responses primed. We therefore analyzed the functionality of primed NS3/4A-specific immune responses in BALB/c (H-2(d)) and/or C57BL/6J (H-2(b)) mice 1, 2, 3, 4, 6, 12 and 16 months after the last immunization. Mice were immunized one, two, three or four times using gene gun delivery to the skin or by intramuscular administration. Immunological responses after immunization were monitored by protection against in vivo challenge of NS3/4A-expressing syngeneic tumor cells. In addition, functionality of the NS3/4A-specific T cells was analyzed by a standard cytotoxicity assay. First, we identified a new unique murine H-2(d)-restricted NS3/4A cytotoxic T lymphocyte (CTL) epitope, which enabled us to study the epitope-specific immune responses. Our results show that the coNS3/4A vaccine was highly immunogenic by determination of interferon-γ/tumor necrosis factor-α production and lytic cytotoxic T cells, which could efficiently inhibit in vivo tumor growth. Importantly, we showed that one to four monthly immunizations protected mice from tumor development when challenged up to 16 months after the last immunization. When determining the functionality of NS3/4A-specific T cells in vitro, we showed detectable lytic activity up to 12 months after the last immunization. Thus, NS3/4A-based DNA vaccines activate potent cellular immune responses that are present and function in both BALB/c and C57BL/6J mice up to 12-16 months after the last immunization. The induction of long-term immunity after NS3/4A DNA immunization has not been shown previously and supports the use of NS3/4A in hepatitis C virus vaccine compositions.

Management of flail chest without mechanical ventilation.

The pathophysiology of flail chest is usually described only on the basis of paradoxical respiration, ignoring underlying pulmonary contusion. Two groups of comparable patients were treated either with early tracheal intubation and mechanical ventilation (Group 1), or with fluid restriction, diuretics, methylpredinisolone, albumin, vigorous pulmonary toilet, and intercostal nerve blocks, ignoring the paradox and treating only the underlying lung (Group 2). When tracheostomy and mechanical ventilation were not used the mortality rate went from 21% to O(p = 0.01), the complication rate from 100% to 20% (p = 0.005), and the average hospitalization from 31.3 to 9.3 days (p = 0.005). We conclude that most patients with flail chest do not need internal pneumatic stabilization if the underlying lung is treated appropriately and that tracheostomy and prolonged mechanical ventilation with a volume respirator, as practiced in most respiratory care centers, is usually a triumph of technique over judgment.

Metabolism of the apoproteins in pulmonary surfactant.

Two proteins having nominal molecular weights of 35,000 and 10,000 daltons are found in pulmonary surfactant. Although experiments on their immunological properties suggest that they share antigenic determinants, their metabolic relationship is unknown. To study this question we injected [14C]palmitic acid or L-[3H]leucine into the femoral vein of 59 puppies. We killed the animals 30 min to 68 h after injection and purified surface-active material from the endobronchial lavage fluid. We isolated the 35,000 apoprotein, the 10,000 apoprotein, and the saturated phosphatidylcholines in surfactant and measured their specific activities at various times after injection. We found that the 35,000 apoprotein appears in alveolar surfactant with the same time course as saturated phosphatidylcholine but is cleared more rapidly than is the lipid. The specific activity of the 10,000 apoprotein reaches a maximum after that seen for the 35,000 apoprotein and decays with the same turnover time as that of the lipid. The kinetic data suggest that the 10,000 apoprotein is a metabolic product of the 35,000 apoprotein. They are not consistent with the possibility that the 10,000 apoprotein is an artifact of nonspecific degradation during preparation.