BackgroundThe lactase persistent (LP) or lactase non-persistent (LNP) state in European adults is genetically determined by a single nucleotide polymorphism (SNP) located 13.9 kb upstream of the lactase (LCT) gene, known as LCT C>T−13910 (rs4988235). The LNP condition leads to an inability to digest the milk sugar lactose leading to gastrointestinal symptoms and can affect nutrient and calcium intake in certain populations.ObjectivesThe authors studied a group of 51 Chilean patients to assess whether this SNP influences the LP/LNP state in this population, and determined the prevalence of LCT C>T−13910 genotypes in a representative sample of 216 Hispanics and 43 Amerindians with correlation to digestive symptoms.DesignCase–control study done in Chilean patients with clinical suspicion of LNP that were assessed using clinical survey, hydrogen breath test (HBT) and SNP genotyping. The population sample of Hispanics and Amerindians was assessed by clinical survey and SNP genotyping.ResultsOf the 51 patients with clinical suspicion of LNP, 29 were HBT-positive. The CC genotype (LNP) was present in 89.7% of the patients with positive HBT and in only 4.7% of those with negative HBT. The prevalence of the CC genotype was 56.9% in the Hispanic population and 88.3% in Amerindians, and was associated with a higher self-reported clinical intolerance to ingestion of dairy products.ConclusionThe LP/LNP state is determined by the LCT C>T−13910 variant in Chileans. This variant predicts digestive symptoms associated with the ingestion of lactose and is a good tool for the diagnosis of primary adult hypolactasia. The LCT T−13910 allele is rare in the Amerindian population and is suggestive of European ancestry in this contemporary population.

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Above and below-ground biomass and necromass dynamics were assessed for 3 grassland sites located at 550, 850, and 1,025 m elevation in Sierra de la Ventana range (38˚1'S 62˚2'W) in Argentina. The objective was to determine if differences existed in dry matter structure, mycorrhizae infection, net primary productivity (NPP) partitioning to aboveground and belowground tissues, senescence and litter fall, and seasonal patterns of dry matter fluxes with altitude. Soil properties, water budgets and temperature at the sites were also assessed. Biomass plus necromass (without litter) was 1,184 ± 41, 1,208 ± 70, and 1,507 ± 63 gDM m-2 for the lower, intermediate and upper sites, respectively. The below:aboveground biomass ratio increased with elevation. Total NPP was 1,131, 1,280, and 1,157 gDM m-2 y e a r-1 , respectively, for the 3 grassland sites. belowground allocation of net productivity increased with altitude. Both mass and proportion of thin roots increased with elevation, and so did mycorrhizae infection. The aboveground and belowground turnover rates decreased with altitude, but rates were faster for aboveground tissues. We found different temporal patterns in productivity, senescence and disappearance among grassland sites despite similar total NPP. Water holding capacity of soils and temperature were important factors related to several of the observed trends in structure and function. Differences in grassland structure and fluxes are discussed as related to soils and local climate at each site.

The purpose of this study was to analyze the levels of white blood cells and profile of proinflammatory Th1, Th2, Th17, and T regulatory tissue cytokines in the tonsils of periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) patients to contribute to the pathophysiological understanding of the PFAPA syndrome. A cohort of PFAPA patients who had tonsillectomy during 2010 and 2011 was included and compared to control patients who had tonsillectomy for tonsillar hypertrophy. White blood cell counts were measured during flares in PFAPA patients and before tonsillectomy in the control group. Cytokine gene expression was analyzed in removed tonsils by real-time PCR. Nine PFAPA patients with a median age of 5.3 years (1.7-8 years) and 17 hypertrophic tonsils of patients with a median age of 4.8 years (2.3-8.4 years) participated in this study. Tonsillectomy was performed during afebrile period between PFAPA flares. Three of the nine patients had recurrent episodes of aphthous stomatitis without fever after tonsillectomy. Leukocyte and neutrophil counts were higher in PFAPA patients compared to controls (p < 0.05). Eosinophil counts were lower in PFAPA patients during flares (p = 0.006). IL-1β, TNF-α, TGF-β, IL-17, and IFN-γ levels were similar in the tonsils of patients and controls. IL-4 gene expression in the tonsils was lower in PFAPA patients compared to those of the controls (p = 0.04). Proinflammatory, effector, and regulatory cytokine gene expression in tonsil tissue of PFAPA children removed in a noninflammatory asymptomatic interval and in control patients were similar. However, IL-4 cytokine gene expression in the tonsils and peripheral blood eosinophils were lower in the PFAPA patients suggesting a potential pathogenesis pathway based on an inhibition of Th2 responses.