Alveolar inflammation in cystic fibrosis

In infected lungs of the cystic fibrosis (CF) patients, opportunistic pathogens and mutated cystic fibrosis transmembrane conductance regulator protein (CFTR) contribute to chronic airway inflammation that is characterized by neutrophil/macrophage infiltration, cytokine release and ceramide accumulation. We sought to investigate CF lung inflammation in the alveoli.

Pineal calcification in Alzheimer's disease: an in vivo study using computed tomography

Melatonin has been postulated to have diverse properties, acting as an antioxidant, a neuroprotector, or a stabilizer within the circadian timing system, and is thus thought to be involved in the aging process and Alzheimer's disease (AD). We used computed tomography to determine the degree of pineal calcification (DOC), an intra-individual melatonin deficit marker, as well as the size of uncalcified pineal tissue, in 279 consecutive memory clinic outpatients (AD: 155; other dementia: 25; mild cognitive impairment: 33; depression: 66) and 37 age-matched controls. The size of uncalcified pineal tissue in patients with AD (mean 0.15 cm(2) [S.D. 0.24]) was significantly smaller than in patients with other types of dementia (0.26 [0.34]; P=0.038), with depression (0.28 [0.34]; P=0.005), or in controls (0.25 [0.31]; P=0.027). Additionally, the DOC in patients with AD (mean 76.2% [S.D. 26.6]) was significantly higher than in patients with other types of dementia (63.7 [34.7]; P=0.042), with depression (60.5 [33.8]; P=0.001), or in controls (64.5 [30.6]; P=0.021). These two findings may reflect two different aspects of melatonin in AD. On the one hand, the absolute amount of melatonin excretion capability, as indicated by uncalcified pineal volume, refers to the antioxidant properties of melatonin. On the other hand, the relative reduction in melatonin production capability in the individual, as indicated by DOC, refers to the circadian properties of melatonin.

Exploring the genetic link between RLS and ADHD

Attention deficit/hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder of childhood onset. Clinical and biological evidence points to shared common central nervous system (CNS) pathology of ADHD and restless legs syndrome (RLS). It was hypothesized that variants previously found to be associated with RLS in two large genome-wide association studies (GWA), will also be associated with ADHD. SNPs located in MEIS1 (rs2300478), BTBD9 (rs9296249, rs3923809, rs6923737), and MAP2K5 (rs12593813, rs4489954) as well as three SNPs tagging the identified haplotype in MEIS1 (rs6710341, rs12469063, rs4544423) were genotyped in a well characterized German sample of 224 families comprising one or more affected sibs (386 children) and both parents. We found no evidence for preferential transmission of the hypothesized variants to ADHD. Subsequent analyses elicited nominal significant association with haplotypes consisting of the three SNPs in BTBD9 (chi2 = 14.8, df = 7, nominal p = 0.039). According to exploratory post hoc analyses, the major contribution to this finding came from the A-A-A-haplotype with a haplotype-wise nominal p-value of 0.009. However, this result did not withstand correction for multiple testing. In view of our results, RLS risk alleles may have a lower effect on ADHD than on RLS or may not be involved in ADHD. The negative findings may additionally result from genetic heterogeneity of ADHD, i.e. risk alleles for RLS may only be relevant for certain subtypes of ADHD. Genes relevant to RLS remain interesting candidates for ADHD; particularly BTBD9 needs further study, as it has been related to iron storage, a potential pathophysiological link between RLS and certain subtypes of ADHD.

Influence of nitrogen deficiency on senescence and the amounts of RNA and proteins in wheat leaves

Senescence-associated coordination in amounts of enzymes localized in different cellular compartments were determined in attached leaves of young wheat (Triticum aestivum L. cv. Arina) plants. Senescence was initiated at the time of full leaf elongation based on declines in total RNA and soluble protein. Removal of N from the growth medium just at the time of full leaf elongation enhanced the rate of senescence. Sustained declines in the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39), and a marked decrease in the rbcS transcripts, just after full leaf elongation indicated that Rubisco synthesis/degradation was very sensitive to the onset of senescence. Rubisco activase amount also declined during senescence but the proportion of rca transcript relative to the total poly A RNA pool increased 3-fold during senescence. Thus, continued synthesis of activase may be required to maintain functional Rubisco throughout senescence. N stress led to declines in the amount of proteins located in the chloroplast, the peroxisome and the cytosol. Transcripts of the Clp protease subunits also declined in response to N stress, indicating that Clp is not a senescence-specific protease. In contrast to the other proteins, mitochondrial NADH-glutamate dehydrogenase (EC 1.4.1.2) was relatively stable during senescence and was not affected by N stress. During natural senescence with adequate plant nitrate supply the amount of nitrite reductase (EC 1.7.7.1) increased, and those of glutamine synthetase (EC 1.4.7.1) and glutamate synthase (EC 6.3.1.2) were stable. These results indicated that N assimilatory capacity can continue or even increase during senescence if the substrate supply is maintained. Differential stabilities of proteins, even within the same cellular compartment, indicate that proteolytic activity during senescence must be highly regulated.

Coordination of protein and mRNA abundances of stromal enzymes and mRNA abundances of the Clp protease subunits during senescence of Phaseolus vulgaris (L.) leaves

Our objective was to determine the coordination of transcript and/or protein abundances of stromal enzymes during leaf senescence. First trifolioliate leaves of Phaseolus vulgaris L. plants were sampled beginning at the time of full leaf expansion; at this same time, half of the plants were switched to a nutrient solution lacking N. Total RNA and soluble protein abundances decreased after full leaf expansion whereas chlorophyll abundance remained constant; N stress enhanced the decline in these traits. Abundances of ribulose-1,5-bisposphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39), Rubisco activase and phosphoribulokinase (Ru5P kinase; EC 2.7.1.19) decreased after full leaf expansion in a coordinated manner for both treatments. In contrast, adenosine diphosphate glucose (ADPGlc) pyrophosphorylase (EC 2.7.7.27) abundance was relatively constant during natural senescence but did decline similar to the other enzymes under N stress. Northern analyses indicated that transcript abundances for all enzymes declined markedly on a fresh-weight basis just after full leaf expansion. This rapid decline was particularly strong for the Rubisco small subunit (rbcS) transcript. The decline was enhanced by N stress for rbcS and Rubisco activase (rca), but not for Ru5P kinase (prk) and ADPGlc pyrophosphorylase (agp). Transcripts of the Clp protease subunits clpC and clpP declined in abundance just after full leaf expansion, similar to the other mRNA species. When Northern blots were analyzed using equal RNA loads, rbcS transcripts still declined markedly just after full leaf expansion whereas rca and clpC transcripts increased over time. The results indicated that senescence was initiated near the time of full leaf expansion, was accelerated by N stress, and was characterized by large decline in transcripts of stromal enzymes. The decreased mRNA abundances were in general associated with steadily declining stromal protein abundances, with ADPGlc pyrophosphorylase being the notable exception. Transcript analyses for the Clp subunits supported a recent report (Shanklin et al., 1995, Plant Cell 7: 1713--1722) indicating that the Clp protease subunits were constitutive throughout development and suggested that ClpC and ClpP do not function as a senescence-specific proteolytic system in Phaseolus.

Moderately High Temperatures Inhibit Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase (Rubisco) Activase-Mediated Activation of Rubisco

We tested the hypothesis that light activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is inhibited by moderately elevated temperature through an effect on Rubisco activase. When cotton (Gossypium hirsutum L.) or wheat (Triticum aestivum L.) leaf tissue was exposed to increasing temperatures in the light, activation of Rubisco was inhibited above 35 and 30°C, respectively, and the relative inhibition was greater for wheat than for cotton. The temperature-induced inhibition of Rubisco activation was fully reversible at temperatures below 40°C. In contrast to activation state, total Rubisco activity was not affected by temperatures as high as 45°C. Nonphotochemical fluorescence quenching increased at temperatures that inhibited Rubisco activation, consistent with inhibition of Calvin cycle activity. Initial and maximal chlorophyll fluorescence were not significantly altered until temperatures exceeded 40°C. Thus, electron transport, as measured by Chl fluorescence, appeared to be more stable to moderately elevated temperatures than Rubisco activation. Western-blot analysis revealed the formation of high-molecular-weight aggregates of activase at temperatures above 40°C for both wheat and cotton when inhibition of Rubisco activation was irreversible. Physical perturbation of other soluble stromal enzymes, including Rubisco, phosphoribulokinase, and glutamine synthetase, was not detected at the elevated temperatures. Our evidence indicates that moderately elevated temperatures inhibit light activation of Rubisco via a direct effect on Rubisco activase.