T. A. Standaert

Repeat administration of an adenovirus vector encoding cystic fibrosis transmembrane conductance regulator to the nasal epithelium of patients with cystic fibrosis.

Cystic fibrosis (CF) is a common autosomal recessive disease caused by mutations in the CF transmembrane conductance regulator gene. Recombinant adenoviruses have shown promise as vectors for transfer of CF transmembrane conductance regulator cDNA to airway epithelia and correction of the Cl- transport defect. However, because adenovirus-mediated gene transfer is transient, use of adenovirus as a vector for treatment of CF would require repeated administration. Therefore, we evaluated repeat administration of an adenovirus vector to the nasal epithelium of patients with CF with five escalating doses of up to 10(10) infectious units. There were no detectable adverse affects. All subjects were initially seropositive but developed additional humoral immune responses. The vector partially corrected the defect in airway epithelial Cl- transport in some subjects, although there was variability between subjects and there was less correction with subsequent administration, perhaps because the immune response limited gene transfer. Future work must focus on vectors with increased efficiency and with the ability to evade host defenses.

Changes in hyaluronan deposition during early respiratory distress syndrome in premature monkeys.

ABSTRACT: Increased deposition of hyaluronan (HA) is part of the early response to fibrogenic stimulus in the lung exposed to bleomycin injury and has been associated with increased lung water in adult animals. Early respiratory distress syndrome (RDS) in premature infants is characterized by increased lung water, and late sequelae include fibrosis or bronchopulmonary dysplasia. We hypothesized that increased MA in the alveolar interstitium would be associated with increasingly severe RDS in prematurely delivered monkeys and that modes of therapy that affect severity of disease such as treatment with high-frequency oscillatory ventilation or exogenous surfactant would decrease this response. Thirty-four Macaca nemestrina monkeys were delivered at 134 ± 1 d (term = 168 d) and randomized to high-frequency oscillatory ventilation or conventional mechanical ventilation from birth. Sixteen of these animals received surfactant. At 6 h of age, the right lower lung was frozen in situ during inflation to 30 cm H2O (approximately 2940 Pa) and then dehydrated and processed for microscopy. The presence and severity of RDS were evaluated by clinical and morphologic criteria. HA concentrations in lung extracts increased with progressively severe RDS (p = 0.0003). Treatment with high-frequency oscillatory ventilation decreased the lung injury score (1.69 ± 0.7 compared with 2.5 ± 0.9, p = 0.05), but changes in lung HA concentration did not reach significance (37.9 ± 22.7 compared with 44.8 ± 22.6). Surfactant treatment decreased lung HA concentration (29.6 ± 19.0 μg/wet lung) compared with non-surfactant-treated animals (54.7 ± 20.2 μg/g wet lung, p = 0.0009). Two fetal animals (144 and 163 d gestation) and seven additional premature animals ventilated for up to 96 h were compared with the animals killed at 6 h. HA concentrations increased with length of mechanical ventilation and severity of illness in these animals. HA was localized in freeze-dried lung sections using a biotinylated probe. Lung sections were blindly scored for the distribution of HA staining, and these scores were positively correlated with HA concentration measurements (r = 0.75, p < 0.0001). The quantity of HA in alveolar microvasculature correlated with severity of RDS (r = 0.68, p = 0.0004). We conclude that 1) HA concentration in RDS lungs of prematurely delivered infant monkeys is increased relative to normal lungs at 6 h, 2) increased HA is localized predominantly to the perivascular space of lung vasculature, and 3) this response is decreased by surfactant treatment.

Effects of the Thromboxane Synthetase Inhibitor, Dazmegrel (UK 38,485), on Pulmonary Gas Exchange and Hemodynamics in Neonatal Sepsis

ABSTRACT. Group B streptococcal (GBS) sepsis produces arterial hypoxemia in newborns. In piglets we previously found that hypoxemia develops because of increased ventilation perfusion heterogeneity, and reduced mixed venous pO2 occurring in association with decreased pulmonary blood flow. We hypothesize that increased thromboxane A2 (TxA2) synthesis mediates the immediate alterations in gas exchange found in GBS sepsis. We studied 18 anesthetized, ventilated piglets before, during, and after a 30-min infusion of 2 × 109 colony forming units/kg of GBS. Nine piglets were pretreated with 8 mg/ kg of dazmegrel (DAZ), a TxA2 synthetase inhibitor, and nine animals received GBS without DAZ pretreatment. Pulmonary and systemic arterial pressures, pulmonary vascular resistance, pulmonary blood flow, respiratory gas tensions, intrapulmonary shunt, and SD of pulmonary blood flow, an index of ventilation perfusion mismatching, were measured. Systemic and pulmonary arterial levels of thromboxane B2 and 6-keto-PGF1α were also measured. The sham-treated animals showed the expected rise in pulmonary arterial pressure from 12 ± 3 to 29 ± 7 torr, (p<0.02). By comparison, the animals pretreated with DAZ did not demonstrate pulmonary arterial hypertension and had a delay in the fall in pulmonary blood flow until 2 h postinfusion. Arterial PO2 did not decline significantly after the GBS infusion in the DAZ-pretreated animals; the untreated animals showed a significant fall in pO2 from baseline. There was no significant change in intrapulmonary shunt or SD of pulmonary blood flow compared to baseline in the DAZ-pretreated animals. The elevation in thromboxane B2 occurring with GBS sepsis did not occur in the DAZ-pretreated animals. We conclude that TxA2 in part mediates the immediate gas exchange and pulmonary hemodynamic abnormalities during GBS sepsis. Inhibition of TxA2 synthetase results in preservation of normal pulmonary gas exchange and a delay in the fall in Qp following GBS infusion.

HYPOXIC VENTILATORY RESPONSE IN THE NEWBORN MONKEY

Summary: The hypoxic ventilatory response was determined in twelve unanesthetized newborn monkeys, Macaca nemestrina, Measurements of blood gases and ventilation were made during normoxia and hypoxia at the postnatal ages of 2, 7, and 21 days, Data were collected during quiet sleep. The infant monkey demonstrated a definite but transient hyperventilatory response following exposure to a Fi02 of 0.12 or 0.14 on the second day of life. Baseline ventilation increased 15% (Fi02 = 0.14) and 28% (Fi02 0.12) after 1 minute of hypoxia; p. 0.05 in both instanes. Return to baseline ventilation occurred between 3 and 5 minutes after hypoxic stimulus onset. This biphasic response to hypoxia converted to an adult-like, sustained hyperventilation during the ensuing three weeks of postnatal maturation. Episodes of periodic breathing and/or apnea were noted to occur during the induced hypoxemia. These data demonstrate that the infant subhuman primate has a ventilatory response to hypoxia that is similar to that of the human infant and is an excellent model for the study of the maturation of the respiratory control system.Speculation: The mechanisnis involved i n the unique neonatal response to hypoxia have not been elucidated. In light of current evidence, direct suppression of respiratory center output by an inhibitor seems the most likely possibility.However, adverse alterations in pulmonary mechanics brought on by the hypoxia itself or fatigue of the carotid body remain viable alternatives.

Cutaneous gas exchange in snakes

SummaryCutaneous aquatic gas exchange and pulmonary gas exchange have been compared in an aquatic snakeAchrochordus javanicus and the terrestrial snakeConstrictor constrictor.Gas exchange was measured by closed respirometry with the snakes in air and in water with access to air. Frequency of air breathing, tidal volumes and total lung volumes were also compared in the two species. All measurements were done at 20–22 ° C.The aquaticAchrochordus showed long periods of apnea in submerged condition interrupted by short periods of breathing activity at the surface. Average frequency of air breathing activity was 2.6 times per hour. Breathing in constrictor was more frequent but irregular with an average frequency of 143 breaths per hour.Total lung volume was 66±31 ml/kg body weight and 72.5±59 ml/kg body weight inAchrochordus andConstrictor, respectively. Tidal volumes were 41.5±4.4 ml/kg body weight and 29.5±14.8 ml/kg body weight, largest inAchrochordus. Constrictor had the highest total O2 uptake (

Relation of myocardial oxygen consumption and function to high energy phosphate utilization during graded hypoxia and reoxygenation in sheep in vivo.

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Lung Development in the Fetal Primate Macaca Nemestrina. III. HMD

) correlating with a higher activity. Total gas exchange ratio (RE) was 0.69 forConstrictor and 0.77 forAchrochordus. InConstrictor air breathing accounted for 97% of the total