Search results for " Gradient"
showing 10 items of 575 documents
Imprints of latitude, host taxon, and decay stage on fungus-associated arthropod communities
2022
Interactions among fungi and insects involve hundreds of thousands of species. While insect communities on plants have formed some of the classic model systems in ecology, fungus-based communities and the forces structuring them remain poorly studied by comparison. We characterize the arthropod communities associated with fruiting bodies of eight mycorrhizal basidiomycete fungus species from three different orders along a 1200-km latitudinal gradient in northern Europe. We hypothesized that, matching the pattern seen for most insect taxa on plants, we would observe a general decrease in fungal-associated species with latitude. Against this backdrop, we expected local communities to be struc…
NMR study of magnetic order, metamagnetic transitions, and low-temperature spin freezing in Ca3Co2O6
2011
We report on a (59)Co NMR investigation of the trigonal cobaltate Ca(3)Co(2)O(6) carried out on a single crystal, providing precise determinations of the electric field gradient and chemical shift tensors, and of the internal magnetic fields at the nonmagnetic Co I sites, unavailable from former studies on powders. The magnetic-field-induced ferri-and ferromagnetic phases at intermediate temperature (e.g., 10 K) are identified by distinct internal fields, well accounted for by purely dipolar interactions. The vanishing transferred hyperfine field at the Co I site indicates that the Co(3+) (I) orbitals do not participate in the intrachain superexchange, in disagreement with a previous theore…
pH distributions in spontaneous and isotransplanted rat tumours.
1988
Spontaneous mammary tumours of the rat with various degrees of malignancy exhibit similar tissue pH distributions. The mean pH (+/- s.d.) of dysplasia is 7.05 +/- 0.20. In benign tumours the mean pH is 6.95 +/- 0.19 and in malignant tumours it is 6.94 +/- 0.19. In contrast, tumours with the same degree of malignancy but different histologies show different pH distributions. Benign tumours with a higher percentage of fibrous tissue exhibit less acidic pH values than those with larger portions of epithelial cells (delta pH = 0.38 pH units). The pH distribution in the benign tumours is independent of the tumour wet weight up to stages of very advanced growth. In the malignant tumours, a trend …
Isolation of Cholinergic Synaptic Vesicles from the Myenteric Plexus of Guinea-Pig Small Intestine
1980
The acetylcholine-rich myenteric plexus-longitudinal muscle preparation of the guinea-pig small intestine has been subjected to subcellular fractionation using modifications of both classical methods and that originally devised for bulk isolation of cholinergic synaptic vesicles from the electromotor nerve terminals of Torpedo marmorata by means of density gradient centrifugation in a zonal rotor. The latter method gave a vesicle fraction with the highest acetylcholine content so far recorded for a mammalian particulate fraction, 30.9 +/- S.E.M. 1.8 (5) nmol of acetylcholine . mg of protein-1. Electron-microscopical examination showed that it consisted of a homogeneous preparation of vesicl…
Preliminary experience with a transcranial magnetic resonance-guided focused ultrasound surgery system integrated with a 1.5-T MRI unit in a series o…
2018
OBJECTIVETranscranial magnetic resonance–guided focused ultrasound surgery (tcMRgFUS) is one of the emerging noninvasive technologies for the treatment of neurological disorders such as essential tremor (ET), idiopathic asymmetrical tremor-dominant Parkinson’s disease (PD), and neuropathic pain. In this clinical series the authors present the preliminary results achieved with the world’s first tcMRgFUS system integrated with a 1.5-T MRI unit.METHODSThe authors describe the results of tcMRgFUS in a sample of patients with ET and with PD who underwent the procedure during the period from January 2015 to September 2017. A monolateral ventralis intermedius nucleus (VIM) thalamic ablation was pe…
An old method for good new cells
2009
The aim of this work was to demonstrate a greater number of viable cells using a micro-surgical in-situ perfusion to collect rat pancreata compared with the pancreas after exsanguination. We used 3 groups of 20 rats. Perfusion was performed by selective cannulation of the left common iliac artery with administration of UW solution at 4 degrees C. Collected pancreata were digested and cells separated by Ficoll gradient were placed in culture to permit adhesion to dishes. Cells were characterized and tested for viability. We observed a gain of about 14% in the number of viable cells compared with those obtained after exsanguination (P < .001 by chi-square).
Tissue evacuated during joint replacement procedure as a source of mononuclear cells.
2017
Background Different cell populations from bone marrow were used in various clinical trials for cardiac diseases during last decade. Four clinical studies are ongoing in our institution and enroll patients with cardiac diseases, coronary disease, type 2 diabetes, and osteoarthritis. The density gradient is used to separate bone marrow mononuclear cells. Joint replacement procedures were associated with significant loss of tissue. Usually, excess tissue as bone marrow, peripheral blood and fat are removed to clean operation site. The aim of this study is to prove whether removed tissue during joint replacement procedure can be considered as a significant source of mononuclear cells. Methods …
Mathematical models for the diffusion magnetic resonance signal abnormality in patients with prion diseases
2014
In clinical practice signal hyperintensity in the cortex and/or in the striatum on magnetic resonance (MR) diffusion-weighted images (DWIs) is a marker of sporadic Creutzfeldt–Jakob Disease (sCJD). MR diagnostic accuracy is greater than 90%, but the biophysical mechanisms underpinning the signal abnormality are unknown. The aim of this prospective study is to combine an advanced DWI protocol with new mathematical models of the microstructural changes occurring in prion disease patients to investigate the cause of MR signal alterations. This underpins the later development of more sensitive and specific image-based biomarkers. DWI data with a wide a range of echo times and diffusion weightin…
Involvement of microsomal vesicles in part of the sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition in mitochondrial fraction…
1994
Liver mitochondrial fractions as normally isolated contain only 10-20% of total mitochondria and may not be representative of the whole mitochondrial population. This study was designed to evaluate the dependence of the sensitivity of carnitine palmitoyl-transferase I (CPT I) to malonyl-CoA inhibition in mitochondrial fractions that are not normally studied. Four fractions prepared from rat liver were found to be contaminated to different extents by microsome vesicles, on the basis of marker-enzyme activities and micrographic data. Purification of mitochondrial fractions on a Percoll gradient decreased to some extent the microsomal contamination, which was due in part to the existence of cl…
Simultaneous age‐dependent and age‐independent sexual selection in the lekking black grouse(Lyrurus tetrix)
2014
Individuals' reproductive success is often strongly associated with their age, with typical patterns of early‐life reproductive improvement and late‐life senescence. These age‐related patterns are due to the inherent trade‐offs between life‐history traits competing for a limited amount of resources available to the organisms. In males, such trade‐offs are exacerbated by the resource requirements associated with the expression of costly sexual traits, leading to dynamic changes in trait expression throughout their life span. Due to the age dependency of male phenotypes, the relationship between the expression of male traits and mating success can also vary with male age. Hence, using longitu…