| 2. |
- Holmquist, Peter, et al.
(författare)
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Early urinary changes in Tamm-Horsfall protein and epidermal growth factor in diabetic children
- 2001
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Ingår i: Pediatric Nephrology. - : Springer Science and Business Media LLC. - 1432-198X .- 0931-041X. ; 16:6, s. 488-492
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Tidskriftsartikel (refereegranskat)abstract
- Both glomerular and tubular markers have been used to follow diabetic nephropathy. However, neither albumin nor proximal tubular markers have proven useful in prepubertal diabetes. Hence we studied two markers derived from the distal tubular cells, Tamm-Horsfall protein (THP) and epidermal growth factor (EGF), The urinary excretion of THP and EGF was examined in samples obtained during the first 20 days and 1 year after diagnosis of diabetes in children aged 4-15 years. Fourteen children without and 18 with ketonuria were examined, and 17 age-matched healthy children participated as controls. The excretion rate of EGF was increased at diagnosis, while that of THP was not. After 20 days of treatment the excretion of EGF had normalized, while the excretion of THP was decreased. Similar results were obtained after 1 year. In conclusion, in spite of good metabolic control a reduced excretion of THP persisted for at least 1 year after the diagnosis of diabetes. Whether the finding of reduced excretion of THP has any biological significance awaits further study.
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| 5. |
- Stepanauskas, R, et al.
(författare)
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Summer inputs of riverine nutrients to the Baltic Sea: Bioavailability and eutrophication relevance
- 2002
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Ingår i: Ecological Monographs. - 0012-9615. ; 72:4, s. 579-597
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Tidskriftsartikel (refereegranskat)abstract
- Most nitrogen and phosphorus transported by world rivers to the oceans is associated with dissolved organic matter. However, organic matter as a potential source of N and P has hitherto been largely neglected in studies of coastal microbial food webs. We examined 50 rivers, draining a major part of the Baltic Sea watershed, with respect to summer concentrations, chemical composition, and biological availability of N and P. The broad spectrum of rivers studied enabled us to assess whether the input of terrigenous organic matter can be an important nutrient source, at various levels of anthropogenic loading of inorganic N and P. Concentrations of total N and P ranged from 9 to 220 mumol/L and from 0.14 to 5.56 mumol/L, respectively, with the highest concentrations in the southern part of the Baltic Sea drainage area and in several rivers on the Finnish western coast. Urea and dissolved combined amino acids (DCAA) each constituted 4-20% of dissolved organic nitrogen (DON), while dissolved free amino acids (DFAA) made up <3% of DON. The contribution of urea and amino acids to the DON pool was inversely correlated with DON concentration. Bacterial regrowth bioassays in selected rivers demonstrated that similar to30% of DON and similar to75% of dissolved organic phosphorus (DOP) was potentially available to the indigenous bacterial assemblage of the Baltic Sea, and hence susceptible to mineralization within the pelagic food web. Our study is among the first to demonstrate that bacterioplankton are able to utilize a major part of DON and DOP from a broad spectrum of natural waters. The C:N ratio, absorbance spectra, and fluorescence properties of the organic matter suggest that the observed high bioavailability of DON and DOP was due to a large contribution of organic matter from riverine primary production compared to the humic matter derived from terrestrial vascular plants. In addition, algal and bacterial cells dominated the transport of particulate organic material, further enhancing productivity of coastal waters. No correlations were found between DON bioavailability and the fraction of DON bound in urea and amino acids, indicating a utilization of other N compounds (e.g., amides) by the bacteria. We estimate that the input of summer riverine N to the Baltic Sea consists of 48% dissolved inorganic N, 41 % DON, and 11 % particulate N. Corresponding values for phosphorus are 46%, 18%, and 36% of dissolved inorganic P, DOP, and particulate P, respectively. During the thermal summer stratification, when freshwater inputs are trapped in the surface layer, rivers contribute similar to30% of N and similar to5% of P needed to support the export production (plankton sedimenting out of the photic layer) in the Baltic Sea. The high availability to bacteria suggests that DOP is a major stimulator of pelagic productivity in the P-limited northern part of the Baltic Sea. Based on reported concentrations in other areas, we suggest that the global contribution of riverine organic N and P to the primary production of coastal waters is comparable to the contribution of inorganic nutrients.
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