Use of heated humidified high flow nasal cannula for obstructive sleep apnea in infants.

OBJECTIVE: Heated humidified high flow nasal cannula (HHHFNC) has gained popularity in the treatment of children with respiratory distress and bronchiolitis in the past decade. Its efficacy as a mode of non-invasive respiratory support has been demonstrated in both adults and children. However, reports on its use in the treatment of obstructive sleep apnea (OSA) in infants are limited. We aimed to evaluate the efficacy of HHHFNC therapy as treatment in infants with OSA. METHODS: A retrospective analysis of OSA infants who had undergone polysomnographic titration between 2015 and 2017 was undertaken. Data about the age, gender, AHI, co-morbid conditions and flow used for each patient were retrieved. RESULTS: Ten infants were included in this study (median age 34 weeks; IQR 27-38 weeks). The median optimal HHHFNC flow rate was 8.0 L/min (IQR 6.7-8.0 L/min). HHHFNC significantly reduced median obstructive apnea-hypopnea index (OAHI) from 9.1 (IQR 5.1-19.3) to 0.9 (IQR 0-1.6; P = 0.005) events/h; median obstructive apnea index (OAI) from 5.8 (IQR 1.1-13.4) to 0 (IQR 0-0.9; P = 0.021) events/h; median obstructive hypopnea index (OHI) from 4.1 (IQR 0.9-6.8) to 0.1 (0-0.9; P = 0.017) events/h; and median oxygen saturation (SpO2) nadir increased from 88% (IQR 83-94%) to 94% (IQR 93-96%; P = 0.040). CONCLUSION: HHHFNC significantly reduced respiratory events and improved oxygenation in infants with OSA.

Phytochrome C plays a major role in the acceleration of wheat flowering under long-day photoperiod.

Phytochromes are dimeric proteins that function as red and far-red light sensors influencing nearly every phase of the plant life cycle. Of the three major phytochrome families found in flowering plants, phytochrome C (PHYC) is the least understood. In Arabidopsis and rice, PHYC is unstable and functionally inactive unless it heterodimerizes with another phytochrome. However, when expressed in an Arabidopsis phy-null mutant, wheat PHYC forms signaling active homodimers that translocate into the nucleus in red light to mediate photomorphogenic responses. Tetraploid wheat plants homozygous for loss-of-function mutations in all PHYC copies (phyC(AB)) flower on average 108 d later than wild-type plants under long days but only 19 d later under short days, indicating a strong interaction between PHYC and photoperiod. This interaction is further supported by the drastic down-regulation in the phyC(AB) mutant of the central photoperiod gene photoperiod 1 (PPD1) and its downstream target flowering locus T1, which are required for the promotion of flowering under long days. These results implicate light-dependent, PHYC-mediated activation of PPD1 expression in the acceleration of wheat flowering under inductive long days. Plants homozygous for the phyC(AB) mutations also show altered profiles of circadian clock and clock-output genes, which may also contribute to the observed differences in heading time. Our results highlight important differences in the photoperiod pathways of the temperate grasses with those of well-studied model plant species.