ABSTRACT
A fundamental aspect of climate change is the potential shifts in flowering phenology and pollen initiation associated with milder winters and warmer seasonal air temperature. Earlier floral anthesis has been suggested, in turn, to have a role in human disease by increasing time of exposure to pollen that causes allergic rhinitis and related asthma. However, earlier floral initiation does not necessarily alter the temporal duration of the pollen season, and, to date, no consistent continental trend in pollen season length has been demonstrated. Here we report that duration of the ragweed (Ambrosia spp.) pollen season has been increasing in recent decades as a function of latitude in North America. Latitudinal effects on increasing season length were associated primarily with a delay in first frost of the fall season and lengthening of the frost free period. Overall, these data indicate a significant increase in the length of the ragweed pollen season by as much as 13-27 d at latitudes above ~44°N since 1995. This is consistent with recent Intergovernmental Panel on Climate Change projections regarding enhanced warming as a function of latitude. If similar warming trends accompany long-term climate change, greater exposure times to seasonal allergens may occur with subsequent effects on public health.
Subject(s)
Ambrosia , Pollen , Seasons , Temperature , Asthma/etiology , Climate , Humans , North America , Rhinitis, Allergic, Seasonal/etiologySubject(s)
Nasal Cavity/diagnostic imaging , Nose Neoplasms/diagnosis , Paranasal Sinuses/diagnostic imaging , Sinusitis/diagnosis , Chronic Disease , Diagnosis, Differential , Exophthalmos , Humans , Male , Middle Aged , Nasal Cavity/pathology , Paranasal Sinuses/pathology , Radiography , Rhinitis, Allergic, PerennialABSTRACT
BACKGROUND: Sepsis commonly complicates the clinical course of critically ill very low birth weight infants, with as many as 30% developing hospital-acquired bacteremia. The tumor necrosis factor alpha (TNF-alpha) -- 308 G/A single nucleotide polymorphism (SNP) is associated with adverse outcome in septic adult patients. METHODS: One hundred seventy-three mechanically ventilated very low birth weight infants were genotyped for the TNF-alpha -- 308 G/A SNP. RESULTS: One hundred twenty (69%) infants were homozygous GG, 45 (26%) were heterozygous AG and 8 (5%) were homozygous AA; 2 of 120 (2%) infants developed early bacteremia in the GG group, and 1 of 53 (2%) developed early bacteremia in the AA/AG group (P = 0.919). One or more episodes of late bacteremia/fungemia developed in 59 of 120 (49%) infants with the GG genotype and 23 of 53 (43%) infants with the AG/AA genotype (P = 0.484). Endotracheal tube colonization rates were 65 of 120 (54%) for infants with the GG genotypes and 28 of 53 (53%) for infants with the AG/AA genotypes (P = 0.871). Nosocomial pneumonia developed in a similar number of infants in both genotype groups (9 of 120 infants vs. 3 of 53 infants; P = 0.461). Mortality from sepsis was 3 times greater in infants with the AA/AG genotypes than in those with the GG genotype (10%vs. 3%; P = 0.038). This difference in sepsis mortality was even greater when only bacteremic/fungemic infants are considered (4 of 59 infants vs. 6 of 23 infants; P = 0.026). CONCLUSIONS: These data suggest that the TNF-alpha -- 308 A allele does not affect the development of sepsis in ventilated premature infants but may increase mortality once sepsis develops.
