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- Brussaard, Lijbert, et al.
(författare)
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Biodiversity and ecosystem functioning in soil
- 1997
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 26:8, s. 563-570
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Tidskriftsartikel (refereegranskat)abstract
- We review the current knowledge on biodiversity in soils, its role in ecosystem processes, its importance for human purposes, and its resilience against stress and disturbance. The number of existing species is vastly higher than the number described, even in the macroscopically visible taxa, and biogeographical syntheses are largely lacking. A major effort in taxonomy and the training of a new generation of systematists is imperative. This effort has to be focussed on the groups of soil organisms that, to the best of our knowledge, play key roles in ecosystem functioning. To identify such groups, spheres of influence (SOI) of soil biota - such as the root biota, the shredders of organic matter and the soil bioturbators - are recognized that presumably control ecosystem processes, for example, through interactions with plants. Within those SOI, functional groups of soil organisms are recognized. Research questions of the highest urgency are the assignment of species to functional groups and determining the redundancy of species within functional groups. These priorities follow from the need to address the extent of any loss of functioning in soils, associated with intensive agriculture, forest disturbance, pollution of the environment, and global environmental change. The soil biota considered at present to be most at risk are species-poor functional groups among macrofaunal shredders of organic matter, bioturbators of soil, specialized bacteria like nitrifiers and nitrogen fixers, and fungiforming mycorrhizas. An experimental approach in addressing these research priorities is needed, using longterm and large-scale field experiments and modern methods of geostatistics and geographic information systems.
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- Cnattingius, Sven, et al.
(författare)
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The paradoxical effect of smoking in preeclamptic pregnancies : smoking reduces the incidence but increases the rates of perinatal mortality, abruptio placentae, and intrauterine growth restriction
- 1997
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Ingår i: American Journal of Obstetrics and Gynecology. - 0002-9378 .- 1097-6868. ; 177:1, s. 156-61
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Smoking is associated with a reduced risk of preeclampsia, but what is the outcome of pregnancy when preeclampsia develops in women who smoke? STUDY DESIGN: Single births in Sweden from 1987 through 1993 to nulliparous women aged 15 to 34 years (N = 317,652) were included. Poisson regression analyses were used to calculate adjusted relative risks and rates of adverse pregnancy outcomes. RESULTS: Maternal smoking was associated with significantly reduced risks of mild and severe preeclampsia (relative risks = 0.6 and 0.5, respectively). In pregnancies with severe preeclampsia, smoking at least 10 cigarettes per day was associated with increased rates of perinatal mortality (from 24 to 36 per 1000), abruptio placentae (from 31 to 67 per 1000), and being small for gestational age (from 28% to 68%), whereas the corresponding smoking-related increases in rates in nonhypertensive pregnancies were considerably less. CONCLUSIONS: Smokers in whom preeclampsia develops have very high risks of perinatal mortality, abruptio placentae, and small-for-gestational-age infants.
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- Eriksson, Mikael, et al.
(författare)
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Inhibitory receptors alter natural killer cell interactions with target cells yet allow simultaneous killing of susceptible targets
- 1999
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 190:7, s. 1005-1012
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Tidskriftsartikel (refereegranskat)abstract
- Inhibitory receptors expressed on natural killer (NK) cells abrogate positive signals upon binding corresponding major histocompatibility complex (MHC) class I molecules on various target cells. By directly micromanipulating the effector-target cell encounter using an optical tweezers system which allowed temporal and spatial control, we demonstrate that Ly49-MHC class I interactions prevent characteristic cellular responses in NK cells upon binding to target cells. Furthermore, using this system, we directly demonstrate that an NK cell already bound to a resistant target cell may simultaneously bind and kill a susceptible target cell. Thus, although Ly49-mediated inhibitory signals can prevent many types of effector responses, they do not globally inhibit cellular function, but rather the inhibitory signal is spatially restricted towards resistant targets.
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- Eudy, James D., et al.
(författare)
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Mutation of a gene encoding a protein with extracellular matrix motifs in Usher syndrome type IIa
- 1998
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 280:5370, s. 1753-1757
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Tidskriftsartikel (refereegranskat)abstract
- Usher syndrome type IIa (OMIM 276901), an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa, maps to the long arm of human chromosome 1q41 between markers AFM268ZD1 and AFM144XF2. Three biologically important mutations in Usher syndrome type IIa patients were identified in a gene (USH2A) isolated from this critical region. The USH2A gene encodes a protein with a predicted size of 171.5 kilodaltons that has laminin epidermal growth factor and fibronectin type III motifs; these motifs are most commonly observed in proteins comprising components of the basal lamina and extracellular matrixes and in cell adhesion molecules.
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- Holmberg, Niklas, et al.
(författare)
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Transgenic tobacco expressing Vitreoscilla hemoglobin exhibits enhanced growth and altered metabolite production
- 1997
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Ingår i: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1087-0156 .- 1546-1696. ; 15:3, s. 7-244
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Tidskriftsartikel (refereegranskat)abstract
- The gene for Vitreoscilla hemoglobin (VHb) has been introduced and expressed in Nicotiana tabaccum (tobacco). Transgenic tobacco plants expressing VHb exhibited enhanced growth, on average 80-100% more dry weight after 35 days of growth compared to wild-type controls. Furthermore, germination time is reduced from 6-8 days for wild-type tobacco to 3-4 days and the growth phase from germination to flowering was 3-5 days shorter for the VHb-expressing transgenes. Transgenic plants contained, on average, 30-40% more chlorophyll and 34% more nicotine than controls. VHb expression also resulted in an altered distribution of secondary metabolites: In the trangenic tobacco plants anabasine content was decreased 80% relative to control plants.
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- Leblanc, James, et al.
(författare)
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Speech separation by kurtosis maximization
- 1998
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Ingår i: Proceedings of the 1998 IEEE International Conference on Acoustics, Speech, and Signal Processing. - Piscataway, NJ : IEEE Communications Society. - 0780344286 ; , s. 1029-1032
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Konferensbidrag (refereegranskat)abstract
- We present a computationally efficient method of separating mixed speech signals. The method uses a recursive adaptive gradient descent technique with the cost function designed to maximize the kurtosis of the output (separated) signals. The choice of kurtosis maximization as an objective function (which acts as a measure of separation) is supported by experiments with a number of speech signals as well as spherically invariant random processes (SIRPs) which are regarded as excellent statistical models for speech. Development and analysis of the adaptive algorithm is presented. Simulation examples using actual voice signals are presented
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- Nishio, Akiyosho, et al.
(författare)
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Comparative studies of mitochondrial autoantibodies in sera and bile in primary biliary cirrhosis
- 1997
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Ingår i: Hepatology. - : Ovid Technologies (Wolters Kluwer Health). - 0270-9139 .- 1527-3350. ; 25:5, s. 1085-1089
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Tidskriftsartikel (refereegranskat)abstract
- Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by destruction of intrahepatic bile ducts. Although the pathogenesis of this disease is still unknown, high titers of antimitochondrial autoantibodies (AMA) have long been recognized in patient sera. However, little is known about the presence of AMA in bile. In this study, we investigated bile and sera from patients with PBC and healthy controls for the presence of AMA and mitochondrial autoantigens. AMA were detected in the bile of 17 of 19 patients (89.4%) with PBC; they were specifically directed against the pyruvate dehydrogenase complex (PDC-E2) in 15 of 19 patients (78.9%), to the branched-chain 2-oxo-acid dehydrogenase complex E2 (BCOADC-E2) in 6 of 19 patients (31.6%), and to the 2-oxoglutarate dehydrogenase complex E2 (OGDC-E2) in 1 of 19 patients (5.3%). In a comparative study of sera from the same patients, anti-PDC-E2 antibodies were found in 19 of 19 patients (100%), anti-BCOADC in 9 of 19 patients (47.3%), and anti-OGDC-E2 in 4 of 19 patients (21.1%) patients. AMA in bile were always found together with antibodies of corresponding specificities in the serum from the same patient. Immunoglobulin (Ig)A AMA were found in the bile of 9 of 19 patients (47.7%) with PBC; they were specifically directed against PDC-E2 in 8 of 19 patients (42.1%) and to BCOADC in 2 of 19 patients (10.5%). Epitope mapping of IgA anti-PDC-E2 antibodies indicated that, like serum autoantibodies, the immunodominant epitope is directed against the inner lipoyl domain of PDC-E2. The prevalence and antigen reactivity of IgA AMA in sera correlated completely with IgA AMA in bile. Autoantibodies against nuclear envelope pore proteins (gp210) were found in 1 of 8 (12.5%) sera of patients with PBC, but not in bile. Furthermore, and of particular interest, we detected the autoantigens, PDC-E2, OGDC-E2, and BCOADC-E2, in the bile of 12 of 19 patients (63.2%), 9 of 19 patients (47.4%), and 9 of 19 patients (47.4%), respectively; PDC-E2 was found in only 1 of 17 (5.9%) disease controls. Although the presence of AMA in bile may merely reflect the presence of these antibodies in sera, the simultaneous detection of mitochondrial autoantigens in bile suggests an increase of mitochondrial autoantigens at inflammatory sites. Such autoantigens, coupled with AMA, may augment the local immune response and disease progression.
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