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941.
Donna Eileen Stewart  Joel Raskin 《CMAJ》1985,133(10):1001-1006
“Twentieth-century disease”, or “total allergy syndrome”, is a condition attributed to hypersensitivity to the environment that may sometimes be seen as so serious that the patient is incapable of living in the modern world. Although the popular media frequently carry stories about it, there is little scientific literature. It is diagnosed by clinical ecologists, who maintain, among other theories, that susceptible individuals experience an overload in assaults by artificial materials in the environment. The patients usually have multiple ill defined symptoms for which no organic cause can be found, but they vigorously resist psychiatric referral, as they attribute their symptoms to allergy. A group of 18 patients who were purportedly suffering from 20th-century disease were referred to a university psychiatric consultation liaison service. They virtually all had a long history of visits to physicians, and their symptoms were characteristic of several well known psychiatric disorders. The case histories and management of three of them are presented. Although this group of patients may have been atypical in that they had more severe psychologic symptoms, the experience indicates that a psychiatric diagnosis ought to be considered. The symptoms of 20th-century disease have much in common with other conditions known to physicians for centuries.  相似文献   
942.

Aim

Climate change is fundamentally altering habitats, with complex consequences for species across the globe. The Arctic has warmed 2–3 times faster than the global average, and unprecedented sea ice loss can have multiple outcomes for ice‐associated marine predators. Our goal was to assess impacts of sea ice loss on population‐specific habitat and behaviour of a migratory Arctic cetacean.

Location

Arctic Ocean.

Methods

Using satellite telemetry data collected during summer‐fall from sympatric beluga whale (Delphinapterus leucas) populations (“Chukchi” and “Beaufort” belugas), we applied generalized estimating equations to evaluate shifts in sea ice habitat associations and diving behaviour during two periods: 1993–2002 (“early”) and 2004–2012 (“late”). We used resource selection functions to assess changes in sea ice selection as well as predict trends in habitat selection and “optimal” habitat, based on satellite‐derived sea ice data from 1990 to 2014.

Results

Sea ice cover declined substantially between periods, and Chukchi belugas specifically used significantly lower sea ice concentrations during the late than early period. Use of bathymetric features did not change between periods for either population. Population‐specific sea ice selection, predicted habitat and the amount of optimal habitat also generally did not change during 1990–2014. Chukchi belugas tracked during 2007–2012 made significantly more long‐duration and deeper dives than those tracked during 1998–2002.

Main conclusions

Taken together, our results suggest bathymetric parameters are consistent predictors of summer‐fall beluga habitat rather than selection for specific sea ice conditions during recent sea ice loss. Beluga whales were able to mediate habitat change despite their sea ice associations. However, trends towards prolonged and deeper diving possibly indicate shifting foraging opportunities associated with ecological changes that occur in concert with sea ice loss. Our results highlight that responses by some Arctic marine wildlife can be indirect and variable among populations, which could be included in predictions for the future.
  相似文献   
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A new type of horizontal biofilm bioreactor for continuous bioconversion of emulsified oily substrate by immobilized growing biofilm of filamentous fungi was designed, constructed, and feasibility tested. The new reactor design provides "self"-immobilization of homogenized mycelium leading to even biofilm development. This was accomplished by using stainless steel screens of optimal mesh, mounted in parallel and stretching outward from a main rotating axis of a biological rotating contractor. Each screen was equipped with a pair of stainless steel blades mounted on supports allowing for continuous biofilm "shaving" beyond a predetermined thickness, thus retaining freshly growing active biofilm surface. The feasibility of the new bioreactor was demonstrated by decalactone production from emulsified castor oil by immobilized filamentous fungi (Tyromyces sambuceus). The combination of oriented metal screens and moving blades was found to be highly effective for a model system in maintaining stable substrate emulsion in the reactor in either batchwise or continuous processing, as well as maintaining biofilm thickness with continuous removal of excess growing hyphae. (c) 1996 John Wiley & Sons, Inc.  相似文献   
947.
Abstract: Stable introduction of therapeutic genes into hematopoietic stem cells has the potential to reconstitute immunity in individuals with HIV infection. However, many important questions regarding the safety and efficacy of this approach remain unanswered and may be addressed in a non-human primate model. To facilitate evaluation of expression of foreign genes in T cells derived from transduced hematopoietic progenitor cells, we have established a culture system that supports the differentiation of rhesus macaque and human CD34+ bone marrow derived cells into mature T cells. Thymic stromal monolayers were prepared from the adherent cell fraction of collagenase digested fetal or neonatal thymus. After 10–14 days, purified rhesus CD34+ bone marrow-derived cells cultured on thymic stromal monolayers yielded CD3+CD4+CD8+, CD3+CD4+CD8?, and CD3+CD4?CD8+ cells. Following stimulation with mitogens, these T cells derived from CD34+ cells could be expanded over 1,000-fold and maintained in culture for up to 20 weeks. We next evaluated the ability of rhesus CD34+ cells transduced with a retroviral vector containing the marker gene neo to undergo in vitro T cell differentiation. CD34+ cells transduced in the presence of bone marrow stroma and then cultured on rhesus thymic stroma resulted in T cells containing the retroviral marker gene. These studies should facilitate both in vitro and in vivo studies of hematopoietic stem cell therapeutic strategies for AIDS.  相似文献   
948.
During precocious germination, Brassica napus L. embryos exhibitfeatures of embryo maturation and features of post-germinativegrowth at the same time, which raises important questions aboutthe nature of these developmental programmes and the transitionbetween them. To investigate the possiblity that the two programmesare segregated spatially rather than temporallhy in these embryos,embryos of different ages (excised at 38, 47, and 60 d post-anthesis)were placed in culture to induce precocious germination, andtotoal RNA was isolated from the cotyledons and axes or hypocotyls.cDNA sequences (two marking embryo maturation and four markingthe onset of post-germinative growth) were used as probes ondot blots to compare mRNA population dynamics in these organs.We find that individual organs accumulate mRNAs characteristicof only one developmental programme at any given time and concludethat the programmes are both distinct and potentially mutuallyexclusive. Embryos are able to ‘switch’ from accumulatingembryo maturation mRNAs to acumulating post-germinative mRNAsin culture, but the transition occurs at different times indifferent organs. Key words: Precocious germination, Brassica napus, rapeseed, embryo development  相似文献   
949.
Abstract: 5-Hydroxytryptamine (5-HT) receptors contain seven putative transmembrane domains and couple via different guanine nucleotide binding proteins to specific effector enzymes. Studies with other receptors identify the second and third intracellular loops or the C-terminus of the receptor as important for selective effector coupling. However, it is not known which regions of the 5-HT receptor determine effector coupling specificity. To address this question, we constructed a chimeric 5-HT receptor in which the third intracellular (i3) loop is derived from the 5-HT2A receptor, which is coupled to activation of phospholipase C, and the rest of the sequence is derived from the 5-HT1B receptor, which is coupled to inhibition of adenylyl cyclase. The chimeric receptor exhibited ligand binding properties similar to those of the 5-HT1B receptor and distinct from those of the 5-HT2A receptor. This suggests that the i3 loop is not critical for the unique pharmacology of the 5-HT1B receptor. In contrast, the chimeric receptor exhibited signaling properties similar to those of the 5-HT2A receptor and distinct from those of the 5-HT1B receptor. This indicates that the i3 loop determines the effector coupling specificity of the 5-HT2A receptor.  相似文献   
950.
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