Clinical presentation and management of atypical hemolytic uremic syndrome in Latin America: a narrative review of the literature.

INTRODUCTION: Comprehensive information about atypical hemolytic uremic syndrome (aHUS) is relatively scarce outside of Europe and North America. This narrative review assembles available published data about the clinical presentation and management of aHUS in Latin America. AREAS COVERED: A search conducted in February 2023 of the MEDLINE (from inception), Embase (from inception), and LILACS/IBECS (1950 to 2023) databases using search terms 'atypical hemolytic uremic syndrome' and 'Latin America' and their variations retrieved 51 records (full papers and conference abstracts) published in English, Spanish, or Portuguese. After de-duplication, manual screening of titles/abstracts and addition of author-known articles, 25 articles were included of which 17 (68%) are full papers. All articles were published during the years 2013-2022. Articles include cohort studies, a registry analysis, and case reports from Argentina, Brazil, Chile and Columbia. Overall, Latin American patients with aHUS present the classic epidemiological, clinical, and genetic characteristics associated with this condition as described in other world regions. Depending on the country and time of reporting, aHUS in Latin America was treated mainly with plasma therapy and/or eculizumab. Where reported, eculizumab substantially improved aHUS-related outcomes in almost all adult and pediatric patients. EXPERT OPINION: Eculizumab has dramatically altered the natural course of aHUS, improving prognosis and patient outcomes. Addressing economic challenges and investing in healthcare infrastructure will be essential to implement strategies for timely detection and early treatment of aHUS in Latin America.

Germination of small tropical seeds has distinct light quality and temperature requirements, depending on microhabitat.

The coexistence of plant species in tropical rainforests is related to specific abiotic resources, varying according to the occurrence microhabitat of each species. Light quality is the main abiotic factor influencing germination of small seeds; however, studies often do not discriminate its effect from that of light irradiance. This study compared specific requirements for seed germination of ten small-seeded species, with restricted occurrence in only one of three contrasting microhabitats: forest understorey, edge of clearings and open areas. Laboratory experiments were carried out to test temperature regime (constant or fluctuating), light quality (R:FR) and light irradiance (PAR), which reproduce high and low conditions commonly found in the microhabitats. Seed germination of all species occurred between 20 and 30 °C, only seeds of open area species were able to germinate at 35 °C and no species required alternating temperatures to germinate. Irrespective of species and microhabitat, a decrease in the R:FR reduced the germination percentage; however, there were differences in the capacity to germinate at low R:FR. The values of R:FR50% were higher for open area and edge species (0.441-0.345) than for understorey species (0.181-0.109), with few exceptions. For all species and most of the tests, germination was not influenced by PAR. Light quality is the most important light signal for germination of small seeds; irradiance has little effect. Our results suggest two distinct patterns of germination for small-seeded species: open area and edge species are light-demanding and require high R:FR to germinate, while understorey species are shade-tolerant and germinate at low R:FR. These differences are responsible for distinct microhabitat occurrence and help to explain the coexistence of species in tropical forests.

Germination, viability and dormancy of 47 species from threatened tropical montane grassland in southeast Brazil: Implications for ex situ conservation.

To mitigate anthropogenic impacts on plant diversity in tropical montane grasslands, one of the most threatened ecosystems in Brazil, it will be essential to develop ex situ conservation strategies to preserve wild species. The lack of basic research on the seed storage behaviour of grassland species may, however, limit their use for reintroduction and restoration projects. We investigated seed storage behaviour at the community level by comparing the effects of cold-low RH (10 °C; 10% RH) and freezing-low RH (20 °C; 10% RH) conditions on seed viability, germination and dormancy of 47 species. Fresh seeds of 43% of the species showed primary dormancy. More than half of the species showed high seed survival responses (viability >60%) under both storage temperatures. Despite a variety of dormancy responses among the different species, the low RH storage conditions tested released dormancy for most species during 12- and 30-month storage times. Multivariate analysis of the best (freezing-low RH, 30 months) storage condition evidenced the formation of five distinct groups, three with species having high conservation potential in seed banks. Although further studies are needed to test dormancy-breaking treatments and improve seed conservation practices, this first approach to assessing seed banking techniques could contribute to demand for locally adapted seeds for ecological restoration projects in tropical montane grasslands.

Good Outcomes in Kidney Transplantation With Deceased Donor With Acute Kidney Injury: Donor's Age and Not Acute Kidney Injury Predicts Graft Function.

BACKGROUND: With the increased demand for kidney transplants and the short supply of organs, it is necessary to have a better strategy to evaluate the available organs, especially from donors with acute kidney injury (AKI), because these organs are often rejected for transplantation. METHODS: We evaluated patients undergoing transplantation with kidneys from deceased donors with AKI. The cases were divided into AKI stages according to the Acute Kidney Injury Network (AKIN) criteria. The outcomes examined were delayed graft function (DGF), creatinine (Cr), and creatinine clearance (CrCl) at 6 months after transplantation. RESULTS: We evaluated 101 patients and included 53 in the final model. There was no statistical difference in the demographic characteristics, comorbidities, and immunosuppression according to each AKIN stage, showing a population of homogeneous transplant recipients. Recipients in AKIN stages I, II, and III, respectively had DGF in 72.7%, 61.9%, and 71.4% of cases; Cr of 1.6 ± 0.5, 1.7 ± 0.7, and 1.6 ± 0.2 mg/dL at 6 months; and CrCl of 60.6 ± 22.4, 52.4 ± 27.4, and 52.03 ± 12.1 mL/min at 6 months. Each additional year in donor age increased the relative risk of DGF by 1.08 (1.0-1.13) (P = .01), and organs from older donors were associated with worse renal function at 6 months. CONCLUSION: Kidney transplantation of organs from deceased donors with AKI showed greater DGF but good outcomes. Donor age was the only characteristic that correlated with outcome.

Methods of analysis for peritubular capillaritis and glomerulitis in acute renal rejection: capillaritis in management of routine diagnosis.

Glomerulitis and peritubular capillaritis have been recognized as important lesions in acute renal rejection (AR). We studied glomerulitis and peritubular capillaritis in AR by 2 methods and investigated associations with C4d, type/grade of AR, and allograft survival time. Glomerulitis was measured according to Banff scores (glomerulitis by Banff Method [gBM]) and by counting the number of intraglomerular inflammatory cells (glomerulitis by Quantitative Method [gQM]). Capillaritis was classified by the Banff scoring system (peritubular capillaritis by Banff Method [ptcBM]) and by counting the number of cells in peritubular capillaries in 10 high-power fields (hpf; peritubular capillaritis by Quantitative Method [ptcQM]). These quantitative analyses were performed in an attempt to improve our understanding of the role played by glomerulitis and capillaritis in AR. The g0 + g1 group (gBM) associated with negative C4d (P = .02). In peritubular capillaritis, a larger number of cells per 10 hpf in peritubular capillaries (ptcQM) were observed in positive C4d cases (P = .03). The group g2 + g3 (gBM) correlated with graft loss (P = .01). Peritubular capillaritis was not significantly related to graft survival time. Our study showed that the Banff scoring system is the best method to study glomerulitis and observed that the evaluation of capillaritis in routine biopsies is difficult and additional studies are required for a better understanding of its meaning in AR biopsy specimens of renal allografts.

Role of peritubular capillaries and vascular endothelial growth factor in chronic allograft nephropathy.

OBJECTIVE: To investigate the role of peritubular capillary damage and vascular endothelial growth factor (VEGF) in chronic allograft injury and to evaluate their correlation with clinical factors. PATIENTS AND METHODS: The study included 56 patients who underwent transplantation between 1987 and 2004 and experienced chronic graft dysfunction. CD34 (peritubular capillaries) and VEGF were evaluated at histologic analysis. Patients were classified into 3 groups: 47 with chronic allograft injury, 9 with pure cyclosporine toxicity, and 26 who served as the control group (time 0 biopsy). RESULTS: Compared with the control group, CD34 total expression in chronic nephropathy was indirectly proportional to Banff stage (P < .05), and VEGF was increased in chronic allograft injury grade I or II or nephrotoxicity (P < .05). CD34 expression was correlated with age (P < .007) and number of acute rejection episodes (P = .005). A negative correlation was observed between expression of CD34 and of VEGF (P < .001). Low expression of CD34 was associated with risk of graft loss of 1.45 (95% confidence interval, 1.15-7.24; P = .04). CONCLUSION: Peritubular capillaries decreased progressively with development of chronic allograft injury. The VEGF demonstrated a bimodal behavior, increasing at the onset of nephropathy and decreasing in the final stages. Loss of peritubular capillaries was associated with worse graft survival and overexpression of VEGF.