Information on morphological and functional effects of anemia in kidney is scarce, although this organ plays a major role in erythropoietin production, which is strongly stimulated in anemia. We undertook a morphological study of kidneys of anemic rats. Anemia was induced by X-irradiation and subsequent injection of a hemolytic drug. The most striking effects of anemia on renal morphology were damages in the proximal tubule and a volume increase of the peritubular space. These effects were evident only in the cortical labyrinth. Morphometry showed that the enlargement of the peritubular space reflected an increase of the volumes of both capillaries and interstitium. The structural changes in the cortical interstitium were associated with increased activity of the ecto-5'-nucleotidase in the fibroblasts. We suggest that hypoxia accounts for most of the observed alterations. The hypoxic proximal tubule might release the nucleotide AMP, which would be hydrolyzed to adenosine by the ecto-5'-nucleotidase in the interstitium. Adenosine has been reported to trigger the synthesis of erythropoietin and the growth of blood capillaries.
A nonradioactive method for the detection of insulin-like growth factor-binding proteins (IGFBPs) was developed utilizing human recombinant insulin-like growth factor-I (IGF-I) biotinylated with N-hydroxysuccinimido-biotin. Human plasma samples were separated by 15% SDS polyacrylamide gel electrophoresis, and proteins were transferred to nitrocellulose by Western blotting. The nitrocellulose sheets were incubated overnight with IGF-I-biotin at 4°C. The next day streptavidin-peroxidase was added for 1 h, and IGFBPs were visualized by an enhanced chemiluminescence system. Five characteristic bands with molecular weights of 41 and 39 (IGFBP-3), 34 (IGFBP-2), 30 (IGFBP-1) and 24 kD (IGFBP-4) were detected. Binding was specific for IGFs, since unlabeled IGF-I inhibited IGF-I-biotin binding. IGFBP ligand blots with biotinylated IGF-I and 125I-IGF-I yielded comparable results. The suitability of the new assay for clinical purposes was demonstrated by several clinical examples. In summary, a rapid, reliable, nonradioactive assay for qualitative analysis of IGFBPs has been developed.
The combination of meaning-bearing units (e.g., words) into higher-order structures (e.g., compound words and phrases) is integral to human language. Despite this central role of syntax in language, little is known about its evolutionary progression. Comparative data using animal communication systems offer potential insights, but only a handful of species have been identified to combine meaningful calls together into larger signals. We investigated a candidate for syntax-like structure in the highly social chestnut-crowned babbler (Pomatostomus ruficeps). Using a combination of behavioral observations, acoustic analyses, and playback experiments, we test whether the form and function of maternal contact calls is modified by combining the core “piping” elements of such calls with at least one other call element or call. Results from the acoustic analyses (236 analysed calls from 10 individuals) suggested that piping call elements can be flexibly initiated with either “peow” elements from middle-distance contact calls or adult “begging” calls to form “peow-pipe” and “beg-pipe” calls. Behavioral responses to playbacks (20 trials to 7 groups) of natural peow-pipe and beg-pipe calls were comparable to those of artificially generated versions of each call using peow elements and begging calls from other contexts. Furthermore, responses to playbacks (34 trials to 7 groups) of the three forms of maternal contact calls (piping alone, peow-pipe, beg-pipe) differed. Together these data suggest that meaning encoded in piping calls is modified by combining such calls with begging calls or peow elements used in other contexts and so provide rare empirical evidence for syntactic-like structuring in a nonhuman animal.
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