Randall's plaque: Pathogenesis and role in calcium oxalate nephrolithiasis

The purpose of these studies was to test the hypothesis that Randall's plaque develops in unique anatomical sites of the kidney and their formation is conditioned by specific stone-forming pathophysiologies. We performed intraoperative papillary biopsies from kidneys of idiopathic-calcium oxalate (CaOx), intestinal bypass for obesity, brushite (BR) and cystine stone formers (SF) during percutaneous nephrolithotomy. Tissues were examined by infrared analysis and light and electron microscopy. Our analysis revealed a distinct pattern of mineral deposition and papillary pathology for each type of SF. CaOx SF had interstitial apatite crystals beginning at thin loops of Henle. These deposits termed Randall's plaque are thought to serve as sites for stone attachment. No tubular injury was noted. Intestinal bypass patients possessed intraluminal apatite deposits in inner medullary collecting ducts (IMCD) with associated cell injury. BR SF showed the most severe form of cortical and medullary changes with sites of Randall's plaque, and yellowish intraluminal deposits of apatite in IMCD. Cystine SF had plugging of ducts of Bellini with cystine crystals and apatite deposits in IMCD and loops of Henle. Intratubular sites of crystalline deposits were always associated to adjacent regions of interstitial fibrosis. The metabolic, anatomic, and surgical pathologic findings in four distinct groups of SF clearly show that ‘the histology of the renal papilla from a stone former, is particular to the clinical setting’. We believe our approach to studying stone disease will provide insights into the pathogenesis of stone formation for each type of SF that will lead to improved clinical treatment

Renal crystal deposits and histopathology in patients with cystine stones

We have biopsied the papillae of patients who have cystine stones asking if this stone type is associated with specific tissue changes. We studied seven cystine stone formers (SF) treated with percutaneous nephrolithotomy using digital video imaging of renal papillae for mapping and obtained papillary biopsies. Biopsies were analyzed by routine light and electron microscopy, infrared spectroscopy, electron diffraction, and micro-CT. Many ducts of Bellini (BD) had an enlarged ostium, and all such were plugged with cystine crystals, and had injured or absent lining cells with a surrounding interstitium that was inflamed to fibrotic. Crystal plugs often projected into the urinary space. Many inner medullary collecting ducts (IMCD) were dilated with or without crystal plugging. Apatite crystals were identified in the lumens of loops of Henle and IMCD. Abundance of interstitial Randall's plaque was equivalent in amount to that of non-SF. In the cortex, glomerular obsolescence and interstitial fibrosis exceeded normal. Cystine crystallizes in BD with the probable result of cell injury, interstitial reaction, nephron obstruction, and with the potential of inducing cortical change and loss of IMCD tubular fluid pH regulation, resulting in apatite formation. The pattern of IMCD dilation, and loss of medullary structures is most compatible with such obstruction, either from BD lumen plugs or urinary tract obstruction from stones themselves

Ipercalciuria e nefrolitiasi: Miti e realtà

Abstract non disponibil

Farmer-led approaches to increasing tree diversity in fields and farmed landscapes in Ethiopia

Increasing tree cover and managing trees better on farms in Ethiopia supports livelihoods and the environment but most tree-planting schemes promote only a few species. This research aimed to understand farmers’ tree planting priorities in Oromia, Ethiopia and address challenges involved in meeting them. Tree species and planting niches were elicited through focus group discussions. Participatory trials compared 17 tree species across seven on-farm planting niches and seedling survival and growth patterns were evaluated. Farmers suggested a high diversity of tree species suitable for each niche with fruit species mainly selected for homesteads. The diversity of desired tree species is much higher than that typically available in nurseries or promoted by tree planting projects. Meeting planting demands was difficult because the existing seedling supply does not support diversity. Evaluation of tree survival showed striking differences among species, farms, agroecologies and planting niches. There was high variation in seedling survival amongst the tree species planted on 1893 farm/planting niche locations, indicating impact of local level risk factors attributable to management, biotic and abiotic causes. Growth differences of the six shared species common to both agroecologies across different niches, showed that the effects of species and niche were significant on growth. A farmer-led approach to increasing tree cover that couples understanding of species and planting niche preferences with appropriate seedling supply and management is proposed as a means to increase the diversity of trees in farmed landscapes