The influence of oxalate on renal epithelial and interstitial cells

Most renal stones in humans are composed of calcium oxalate. An increase in urinary oxalate levels has been shown to result in renal epithelial cell injury and crystal retention. However, the underlying mechanisms are unclear. Although the localization of primary stone formation and the associated cells playing the pivotal role in stone formation are still unknown, renal epithelial cells and interstitial cells seem to be involved in this process. The aim of this study was to evaluate the effects of oxalate on distinct renal epithelial and endothelial cells as well as fibroblasts. The first part focused on the toxicity of oxalate on the cells and a potential time- and dose-dependency. In the second part, renal epithelial cells were cultured in a two-compartment model to examine the vulnerability of the tubular or basolateral side to oxalate. LLCPK1, MDCK, renal fibroblast and endothelial cell lines were cultured under standard conditions. In part 1, cells were grown in standard culture flasks until confluent layers were achieved. Sodium oxalate was delivered at final concentrations of 1, 2 and 4 mM to either the apical or basolateral side (plain medium was delivered to the contralateral side). Cell survival was assessed microscopically by trypan blue staining after 1, 2 and 4 h. The influence of oxalate on proliferation and apoptosis induction was also investigated. In the second part, MDCK and LLCPK1 cells were grown in 6-well plates until confluent layers were achieved. Sodium oxalate at the above concentrations was applied, to either the apical or basolateral side and plain medium was delivered to the opposite side. The same protocol was then followed as in part 1. Part 1: sodium oxalate led to a time- and concentration-dependent decline in cell survival that was comparable in LLCPK1 and MDCK. Non-tubular cell lines like fibroblasts and endothelial cells were significantly more vulnerable to oxalate. These observations were reflected by significant impairment to cell proliferation. We could not demonstrate an induction of apoptosis in any cell line. Part 2: both cell lines were more vulnerable to oxalate on the basolateral side. This effect was more pronounced in MDCK cells at high oxalate concentrations (4 mM). Cells are apparently more resistant on the apical (tubular) side. Our results show that sodium oxalate has a negative effect on the growth and survival of renal epithelial cells and, to a greater extent, also fibroblasts and endothelial cells. We could not demonstrate any induction of apoptotic processes which implies a direct induction of cell necrosis. The finding of interstitial calcification and the proximity of tubules, vessels and interstitial cells make involvement of non-tubular renal cells in tissue calcification processes possible. Renal epithelial cells are apparently more vulnerable to oxalate on their basolateral side. Therefore, calcification processes within the interstitium may exert pronounced toxic effects to these cells, leading to inflammation and necrosis. These observations further support the idea of the interstitium as a site of primary stone formation.     

Hematological long-term results of laparoscopic splenectomy for patients with idiopathic thrombocytopenic purpura: a case control study

Background Laparoscopic splenectomy (LS) for idiopathic thrombocytopenic purpura (ITP) appears, when compared to open splenectomy (OS), associated with immediate important advantages. However, in a number of patients splenectomy does not lead to an adequate response, or after initial adequate response a relapse occurs after some time. A relapse may be associated to the presence of accessory spleens and splenosis. The purpose of this study was to compare the operative outcome and the hematological results on the long term of a series of LS with a historic series of OS for the treatment of ITP.Methods A retrospective review was done of 50 consecutive patients who underwent LS for ITP. Patient characteristics, outcome of surgery, and hematological results were compared to a historical group of patients who underwent conventional splenectomy for ITP (n = 31). Response to splenectomy was defined in three groups: complete remission, partial remission, and no response. Grouping was based on hematological data.Results Concerning operative outcome and postoperative complications, there was a significant difference in favor of LS. Moreover, the hematological outcome of both groups showed no differences after a median period of 66 months (OS) and 35 months (LS), respectively.Conclusions Hematological results after laparoscopic splenectomy for ITP are comparable to those after open splenectomy in both the short and the long term.     

How to measure heart rate?

Objective Heart rate has been shown to predict cardiovascular morbidity and mortality in a very reliable and easily accessible manner. The exact definition of the conditions under which heart rate is measured appears to be as crucial as the determinations of blood pressure or plasma catecholamines. It was investigated how accurately heart rate measurements were performed, and conditions were described in 56 studies identified from prominent journals within the Medline database: (a) search phrases were heart rate and rest or resting; (b) publication date was from 1996 to 2001; and (c) publication type was clinical trial.Methods Five conditions were considered as most influential: (a) resting period before measurement; (b) posture of the patient; (c) environmental conditions such as temperature or visual and acoustic stimuli; (d) method used to record heart rate; and (e) data analysis, i.e., derivation from raw data. An average of only 1.7 of those 5 criteria for the determination of heart rate were met in the studies included. Information on conditions of, for example, resting period, or environmental conditions is almost completely lacking.Results and conclusion The data show that a very important risk predictor and treatment target—heart rate—is not reported in a scientifically sufficient manner, even in large trials. Valuable information is lost despite the fact that the investment of adequately defining, controlling, and performing this determination is modest in comparison to the potential gain. It is recommended to standardize heart rate measurements in analogy to that of blood pressure determinations.The experiments comply with the current laws of the country in which they were performed, inclusive of ethics approval.     

Prenatal diagnosis of Crigler-Najjar syndrome type I by single-strand conformation polymorphism (SSCP)

Crigler-Najjar syndrome type I (CN-I) is a rare and severe inherited disorder of bilirubin metabolism, caused by the total deficiency of bilirubin-UDP-glucuronosyltransferase (UGT) activity. Enzymatic diagnosis cannot be performed in chorionic villi or amniocytes as UGT is not active in these tissues. The cloning of the UGT1 gene and the identification of disease-causing mutations have led to the possibility of performing DNA-based diagnosis. Here we report DNA-based prenatal diagnosis of CN-I in two Tunisian families in whom CN-I patients were diagnosed. As we had previously shown that CN-I was, in Tunisia, associated with homozygosity for the Q357R mutation within the UGT1 gene, we were able to detect this mutation in both families and to show that it was easily recognized by single-strand conformation polymorphism (SSCP) analysis. In both cases, SSCP analysis of fetal DNA showed that the fetus was heterozygous for the Q357R mutation. In one family, the pregnancy was carried to term and a healthy baby was born, whereas, in the other family, the pregnancy is still continuing. Thus the prenatal diagnosis of CN-I is possible, provided disease-causing mutations have been identified. SSCP analysis of DNA prepared either from amniocytes or from chorionic villi is a simple, reliable and fast method for prenatal diagnosis.     

Arzneimitteltherapie im Alter aus der Sicht des klinischen Pharmakologen

Polypragmasy (polypharmacotherapy) is often due to the frequent incidence of multimorbidity among elderly patients. This may evoke unpredictable drug-interactions, which often become a reason for hospitalization. Additional medications might be the consequence. Geriatric patients are often characterized by variant pharmacokinetic parameters. Individualized drug-therapy should take into consideration not only the patients' age, liver and kidney functions but also the individual variability of hepatic metabolization and drug-resorption in the intestine based on genetic polymorphisms. Summing up, it is very important to verify a consisting or a new drug-therapy concerning its risk-benefit ratio and if it is needed, to omit or change some of the medications.     

Flavonoids from Dalbergia louvelii and their antiplasmodial activity

Four new flavonoids (1-4), along with 13 known compounds, were isolated from the heartwood of Dalbergia louvelii by following their potential to inhibit in vitro the growth of Plasmodium falciparum. Of the isolated compounds, four known compounds showed antiplasmodial activity with IC(50) values ranging from 5.8 to 8.7 microM, namely, (R)-4' '-methoxydalbergione (5), obtusafuran (6), 7,4'-dihydroxy-3'-methoxyisoflavone (7), and isoliquiritigenin (8). The structures of the new compounds were determined using spectroscopic techniques as 1-(3-hydroxyphenyl)-3-(4-hydroxy-2,5-dimethoxyphenyl)propane (1), spirolouveline (2), (3R)-7,2'-dihydroxy-4',5'-dimethoxyisoflavanone (3), and 3-(2,4-dihydroxy-5-methoxy)phenyl-7-hydroxycoumarin (4), respectively.