Correction of chromosomal point mutations in human cells with bifunctional oligonucleotides.

A sequence-specific genomic delivery system for the correction of chromosomal mutations was designed by incorporating two different binding domains into a single-stranded oligonucleotide. A repair domain (RD) contained the native sequence of the target region. A third strand-forming domain (TFD) was designed to form a triplex by Hoogsteen interactions. The design was based upon the premise that the RD will rapidly form a heteroduplex that is anchored synergistically by the TFD. Deoxyoligonucleotides were designed to form triplexes in the human adenosine deaminase (ADA) and p53 genes adjacent to known point mutations. Transfection of ADA-deficient human lymphocytes corrected the mutant sequence in 1-2% of cells. Neither the RD or TFD individually corrected the mutation. Transfection of p53 mutant human glioblastoma cells corrected the mutation and induced apoptosis in 7.5% of cells.     

Humid air increases airway resistance in asthmatic subjects.

Eight persons with asthma were exposed to seven air conditions varying in temperature (37 degrees C to 49 degrees C [98.6 degrees F to 120.2 degrees F]) and water content (44 mg H2O per liter to 79 mg H2Oper liter) . Normocapnic hyperventilation for three minutes at 40% maximal voluntary ventilation was carried out for each condition. A constant-volume body plethysmograph measured the functional residual capacity and specific airway conductance (SGaw), followed by two forced expiratory manuevers. Measurements were taken before and 1, 5, 10, and 20 minutes after each challenge. Air conditions with 100% relative humidity caused a fall in the SGaw that was maximal in 1 minute. Air conditions at 100% relative humidity caused a greater fall in both the forced expiratory volume in 1 second (FEV1) (P<.05) and the SGaw (P<.005) than did conditions of the same temperature but less water content. At 44 degrees C and 100% relative humidity, the mean percent change in FEV1 and SGaw was -2% and -40%, respectively, at 1 minute after challenge. Of the conditions examined, the optimal temperature was 44 degrees C, and we speculate that the optimal water content is less than 44 mg H2O per liter. Inhaled water concentrations exceeding 44 mg H2O per liter should probably not be used in patients with asthma.