SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Calcium loss from soil has dramatically increased for decades due to the increase of nitrogen input and/or the extension of acid rain, while calcium input into soil has declined substantially for the replacement of superphosphate by ammonium phosphate in fertilization, which intensified the imbalance of calcium input and output in agro-ecosystems, and needed to be solved in the near future for the sustainability of agriculture in such a country like China where the arable land resource is very limited. In recent years, the intensified soil acidification is mainly attributed to the root proton secretion stimulated by fertilization, and the nitrogen input from precipitation near industrialized regions promotes plant growth but results in other nutrients deficiency, which in turn acidifies soil and causes tree death. One of the most important mechanisms of saline soil bioremediation by sesbania is the activation of soil calcium by sesbania's proton secretion and the increase of soil calcium supply for subsequent crops. The present paper summarized the roles of calcium in plant tolerance to the stresses like acidosis, toxic metals, osmosis, ammonium toxicity, drought, extreme temperature (cold or heat shock), anoxia and pathogen infection, and the measures for maintaining soil calcium fertility. It was suggested that the production of ammonium phosphate should not be a pursued target for China's phosphorus fertilizer industry, and the roles of calcium in plant growth should be taken into account in fertilization experimental designs to make the experiments more accurate.
The neurological manifestations of Fabry disease include both peripheral and central nervous system involvement caused by a deficiency of alpha-galactosidase A and accumulation of alpha-D-galactosyl moieties, particularly globotriosylceramide accumulation (Gb3). These are found in Schwann cells and dorsal root ganglia together with deposits in central nervous system neurons. Involvement of the peripheral nervous system affect mainly small Adelta and C fibers and are likely causally related to the altered autonomic function and neuropathic pain found in this disorder. Other related abnormalities to be discussed are hypohidrosis and other abnormalities attributed to autonomic nervous system dysfunction. The function of the peripheral nervous system is somewhat improved by ERT with reduction in neuropathic pain and an improvement of the detection threshold for cold and warm sensation in the hand and foot. Improvement in sweating and heat tolerance is also noted following ERT. Despite those positive results, ERT does not normalize the function of the peripheral nervous system.
Explore the source record for details and available documents.
The hypobaric hypoxia of moderate altitude elicits various mechanisms of acute to subacute physiologic adaptations of the healthy lung: First of all it causes a hyperventilation, which increases the diminished arterial pO2. Because of hypoxemia-induced vasoconstriction, pulmonary arterial hypertension develops. The adrenergic stimulation of the cardiac output also increases the pulmonary perfusion. Most likely because of the diminished density of ambient air there is a measurable increase of exspiratory bronchial flow or, respectively, a diminution of the peripheral airway resistance. In higher altitudes, limitation of oxygen-diffusion under physical exertion is observed. The consequences of acute hypobaric hypoxia for diseased lungs depend on preexisting ventilation/perfusion mismatch or diffusion impairment. Arterial hypoxemia and hence also pulmonary arterial hypertension are increased. In the presence of normal chemoreceptor sensitivity (type pink puffer), a hyperventilation, which is often perceived as dyspnea by the patient, is induced. Mostly patients with chronic obstructive pulmonary disease adapt, however, surprisingly well to moderate altitude. Bronchial asthma improves frequently because allergen concentrations are low and air density is diminished. On the other hand, physical exertion in dry and cold ambient air may also elicit acute asthmatic exacerbations. The assessment of moderate altitude tolerance by patients with chronic lung diseases and prophylactic precautions before the ascent are discussed. The only altitude-specific disease of the healthy lung is the so-called high-altitude pulmonary edema. The major pathogenetic factor for its development is an inadequate or overshooting response to hypobaric hypoxia (nonuniform pulmonary arterial vasoconstriction, diminished hypoxic ventilatory drive, retention of fluid, centralization of blood volume and capillary leak). Prophylactic and therapeutic implications are discussed.
Under extreme conditions of the Arctic and Antarctic, man develops exertional diabetes, which is characterized by (1) decreases in blood insulin levels and in responses of the insular apparatus to glucose load; (2) a reduction in blood sugar; (3) a drop in glucose uptake; (4) lowering of the renal barrier for blood sugar and other low-molecular weight compounds; (5) appearance of urinary sugar and an increase in its nocturnal resting concentration. Exertional diabetes lies in the basis of switching energy metabolism from the carbohydrate to lipid types at high latitudes. The mechanism of this phenomenon is associated with the contra-insular effect of LDL and VLDL. There is a common epitope in the beta-chain of insulin and LDL and VLDL apoprotein B. The existence of the common epitope leads to competition of insulin and apoprotein B for an insulin receptor and reduces tissue glucose uptake.
Vernalization and photoperiod (PP) responses are developmental mechanisms that allow plants to synchronize their growth and reproductive cycles with the seasonal weather changes. Vernalization requirement has been shown to influence the length of time that low-temperature (LT)-induced genes are up-regulated when cereal species are exposed to acclimating temperatures. The objective of the present study was to determine whether expression of LT-induced Wcs and Wcor gene families is also developmentally regulated by PP response. The LT-tolerant, highly short-day (SD)-sensitive barley (Hordeum vulgare L. cv Dicktoo) was subjected to 8-h SD and 20-h long-day PPs at cold-acclimating temperatures over a period of 70 d. A delay in transition from the vegetative to the reproductive stage under SD resulted in an increased level and longer retention of LT tolerance. Similar WCS and WCOR protein homologs were expressed, but levels of expression were much higher in plants acclimated under SD, indicating that the poor LT tolerance of long-day plants was the result of an inability to maintain LT-induced genes in an up-regulated state. These observations indicate that the PP and vernalization genes influence the expression of LT-induced genes in cereals through separate pathways that eventually converge to activate genes controlling plant development. In both instances, the delay in the transition from the vegetative to the reproductive stage produces increased LT tolerance that is sustained for a longer period of time, indicating that the developmental genes determine the duration of expression of LT-induced structural genes.
The analgesic action of neurotropin, a biological compound widely used in Japan with a record of very limited side-effects, was tested in 8 Caucasian normal volunteers. For the pain test, the subjects were requested to immerse the right hand in ice-cold water and to report the appearance of the following sensations: pain threshold (PThr) and tolerance to pain (PTol). Pain sensitivity range (PSR) was calculated by difference between PThr and PTol expressed in s from beginning of immersion. Neurotropin tablets or an indistinguishable inert placebo were administered according to a randomized double-blind cross-over design and their influence in the pain test was investigated during 2 daily sessions. The effects of both treatments were assessed by calculating the difference between initial and post-medication values for each pain response parameter. Under placebo the means of all effects were found to be negative, reflecting the appearance of hyperalgesia under repetitive pain conditions, with neurotropin, the effects on PTol and PSR were positive and significantly different from those of placebo. These results are discussed in terms of possible mechanisms of action: neurotropin analgesic activity could be linked to its kinin release-inhibiting properties or to a reduction in vaso-constriction and hyperalgesia related to an effect on catecholamines.
Sex differences in thermo- and electrocutaneous responsiveness to painful and non-painful stimuli were investigated in 20 women and 20 men. Heat pain, warmth, and cold thresholds were assessed on the hand and foot with a Peltier thermode system. In addition, subjects used magnitude estimation to judge the sensation intensity evoked by temperatures ranging from 38 degrees C to 48 degrees C applied to the forearm. To measure detection, pain, and tolerance thresholds of electrocutaneous sensitivity, electrical pulses were administered to the hand. Magnitude estimates of sensation intensity were assessed for stimuli ranging from 0.5 mA to 4.0 mA. There were no sex differences in heat pain, warmth and cold thresholds. There were significant sex differences in electrical detection, pain and tolerance thresholds, with lower thresholds in women. Correspondingly, magnitude estimates were similar in women and men when using thermal stimuli while women judged stimuli from 2.5 mA on as more intense than men when using electrical stimuli. Despite these discrepancies, the measures for pain responsiveness from the two stimulation methods correlated significantly. In contrast, no significant correlations between the methods were found when considering the responsiveness to non-painful stimuli. The findings help to clarify controversies in the pain literature about sex differences. Results affirming and denying such differences could be obtained within a single sample, with stimulation method as the critical variable.
To understand low temperature and osmotic stress signaling in plants, we isolated and characterized two allelic Arabidopsis mutants, los5-1 and los5-2, which are impaired in gene induction by cold and osmotic stresses. Expression of RD29A-LUC (the firefly luciferase reporter gene under the control of the stress-responsive RD29A promoter) in response to cold and salt/drought is reduced in the los5 mutants, but the response to abscisic acid (ABA) remains unaltered. RNA gel blot analysis indicates that the los5 mutation reduces the induction of several stress-responsive genes by cold and severely diminishes or even completely blocks the induction of RD29A, COR15, COR47, RD22, and P5CS by osmotic stresses. los5 mutant plants are compromised in their tolerance to freezing, salt, or drought stress. los5 plants are ABA deficient, as indicated by increased transpirational water loss and reduced accumulation of ABA under drought stress in the mutant. A comparison with another ABA-deficient mutant, aba1, reveals that the impaired low-temperature gene regulation is specific to the los5 mutation. Genetic tests suggest that los5 is allelic to aba3. Map-based cloning reveals that LOS5/ABA3 encodes a molybdenum cofactor (MoCo) sulfurase. MoCo sulfurase catalyzes the generation of the sulfurylated form of MoCo, a cofactor required by aldehyde oxidase that functions in the last step of ABA biosynthesis in plants. The LOS5/ABA3 gene is expressed ubiquitously in different plant parts, and the expression level increases in response to drought, salt, or ABA treatment. Our results show that LOS5/ABA3 is a key regulator of ABA biosynthesis, stress-responsive gene expression, and stress tolerance.
The effect of different abiotic stresses (extreme temperatures and osmotic stress) on the synthesis of glutathione and hydroxymethylglutathione, on the ratio of the reduced to oxidised forms of these thiols (GSH/GSSG, hmGSH/hmGSSG), and on the glutathione reductase (GR) activity was studied in maize and wheat genotypes having different sensitivity to low temperature stress. Cold treatment induced a greater increase in total glutathione (TG) content and in GR activity in tolerant genotypes of both species than in sensitive ones. The GSH/GSSG and hmGSH/hmGSSG ratios were increased by this treatment only in the frost-tolerant wheat variety. High-temperature stress increased the TG content and the GSH/GSSG ratio only in the chilling-sensitive maize genotype, but GR activity was greater after this treatment in both maize genotypes. Osmotic stress resulted in a great increase in the TG content in wheat and the GR activity in maize. The amount of total hydroxymethylglutathione increased following all stress treatments. These results indicate the involvement of these antioxidants in the stress responses of wheat and maize.
AIMS: To investigate whether Escherichia coli O157:H7 maintains acid tolerance in water meat decontamination washing fluids. METHODS AND RESULTS: A rifampicin-resistant derivative of E. coli O157:H7 strain ATCC 43895 was inoculated (10(5) cfu ml(-1)) in spray-washings from meat sprayed with cold (10 degrees C) or hot (85 degrees C) water, stored at 10 degrees C for up to 14 days, and its acid tolerance was assessed at 2 and 8 days by exposure to broth or new washings adjusted to pH 3.5 or 3.7 with lactic or acetic acid. The pathogen survived in the water washings, but it was outgrown by the natural, Pseudomonas-like flora, and it was sensitized to acid. CONCLUSIONS: The acid tolerance of E. coli O157:H7 decreases following exposure to non-acid, but otherwise stressful, conditions prevailing in water meat washings at 10 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings suggest that the more intense use of water-based technologies should be included in meat decontamination strategies because they may contribute to enhanced meat safety by inducing acid sensitization in E. coli O157:H7.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Previously, we reported on a tomato ERF transcription activator, TERF1, which was concluded to act as a linker between ethylene and osmotic signal pathways. We now report on the regulatory role of TERF1 in ABA sensitivity and drought response during seedling development. Northern blotting analysis indicated that the transcripts of TERF1 were significantly accumulated in response to drought, cold and ABA. TERF1 activated GCC box- or DRE-driven reporter gene expression in transient expression assay, subsequently increasing the tolerance to drought and the osmoticum, PEG6000, in tobacco expressing TERF1. Further tests showed that TERF1 did not affect the seed germination, but greatly enhanced the sensitivity during tobacco seedling development under ABA treatment. This ABA hypersensitivity in transgenic TERF1 tobacco is both indirect ethylene action and expressions of ABA responsive genes, demonstrating that TERF1 is a multifunctional ERF protein that can integrate different stress signal pathways.
Deschampsia antarctica and Colobanthus quitensis are the only vascular plants to have colonized the Maritime Antarctic, which is characterized by its permanently low temperature and frequent summer frosts. To understand how the plants survive freezing temperatures year-round, antifreeze activity was assayed in apoplastic extracts obtained from both non-acclimated and cold-acclimated Antarctic plants. By observing the shape of ice crystals grown in dilution series of the extracts, it was found that D. antarctica had antifreeze activity, but C. quitensis did not. D. antarctica exhibited antifreeze activity in the non-acclimated state and this activity increased after cold acclimation. The antifreeze activity in D. antarctica was labile to proteolysis and high temperature, active over a wide pH range, and associated with molecules greater than 10 kDa in molecular weight. These results show that D. antarctica produces antifreeze proteins that are secreted into the apoplast. When examined by SDS-PAGE, the apoplastic extracts from cold-acclimated D. antarctica exhibited 13 polypeptides. It is concluded that D. antarctica accumulates AFPs as part of its mechanism of freezing tolerance. Moreover, this is the first plant in which antifreeze activity has been observed to be constitutive.
Plants and ectothermic animals use a variety of substances and mechanisms to survive exposure to subfreezing temperatures. Proteinaceous ice nucleators trigger freezing at high subzero temperatures, either to provide cold protection from released heat of fusion or to establish a protective extracellular freezing in freeze-tolerant species. Freeze-avoiding species increase their supercooling potential by removing ice nucleators and accumulating polyols. Terrestrial invertebrates and polar marine fish stabilize their supercooled state by means of noncolligatively acting antifreeze proteins. Some organisms also depress their body fluid melting point to ambient temperature by evaporation and/or solute accumulation.