Optimization of the Tartrate-Resistant Acid Phosphatase Detection by Histochemical Method

According to the new KDIGO (Kidney Disease Improving Global Outcomes) guidelines, the term of renal osteodystrophy, should be used exclusively in reference to the invasive diagnosis of bone abnormalities. Due to the low sensitivity and specificity of biochemical serum markers of bone remodelling,the performance of bone biopsies is highly stimulated in dialysis patients and after kidney transplantation. The tartrate-resistant acid phosphatase (TRACP) is an iso-enzyme of the group of acid phosphatases, which is highly expressed by activated osteoclasts and macrophages. TRACP in osteoclasts is in intracytoplasmic vesicles that transport the products of bone matrix degradation. Being present in activated osteoclasts, the identification of this enzyme by histochemistry in undecalcified bone biopsies is an excellent method to quantify the resorption of bone. Since it is an enzymatic histochemical method for a thermolabile enzyme, the temperature at which it is performed is particularly relevant. This study aimed to determine the optimal temperature for identification of TRACP in activated osteoclasts in undecalcified bone biopsies embedded in methylmethacrylate. We selected 10 cases of undecalcified bone biopsies from hemodialysis patients with the diagnosis of secondary hyperparathyroidism. Sections of 5 μm were stained to identify TRACP at different incubation temperatures (37º, 45º, 60º, 70º and 80ºC) for 30 minutes. Activated osteoclasts stained red and trabecular bone (mineralized bone) was contrasted with toluidine blue. This approach also increased the visibility of the trabecular bone resorption areas (Howship lacunae). Unlike what is suggested in the literature and in several international protocols, we found that the best results were obtained with temperatures between 60ºC and 70ºC. For technical reasons and according to the results of the present study, we recommended that, for an incubation time of 30 minutes, the reaction should be carried out at 60ºC. As active osteoclasts are usually scarce in a bone section, the standardization of the histochemistry method is of great relevance, to optimize the identification of these cells and increase the accuracy of the histomosphometric results. Our results, allowing an increase in osteoclasts contrast, also support the use of semi-automatic histomorphometric measurements.

Impact of Renal Dysfunction on Liver Transplantation: a Retrospective Study in 708 Orthotopic Liver Transplant Recipients

Renal dysfunction often complicates the course of orthotopic liver transplant recipients and is associated with increased morbid -mortality. The aims of this study were to determine the incidence of chronic renal disease and its impact on patient survival. Clinical data included age, gender and weight,aetiology of hepatic failure, presence of diabetes,hypertension, hepatitis B and C infection, renal dysfunction pretransplant and immunosuppression. Laboratory data included serum creatinine at days 1, 7, 21, month 6, 12 and yearly. The glomerular filtration rate was determined by Cockcroft-Gault equation. We studied retrospectively from September 1992 to March 2007 708 orthotopic liver transplant recipients. Mean age 44±12.6 years, 64% males, 17% diabetic, 18.8% hypertensive, 19.9% with hepatitis C and 3.8% hepatitis B. Renal dysfunction pretransplant was known in 21.6%. Mean follow-up was 3.6 years. Mean transplant survival 75% at 12 months. 154 patients died. Univariate and multivariate analyses were performed and a p<0.05 was considered significant. Acute kidney injury occurred in 33.2%. Chronic kidney disease stage 3 was observed in 34.3%,stage 4 in 6.2% and stage 5 in 5.1%. At the time of this study, 46.4% were on Cyclosporine A, 44.7% on tacrolimus and 8.9% on sirolimus. Using multivariate analysis, renal dysfunction was correlated with renal dysfunction pre -orthotopic liver transplant (p<0.001), acute kidney injury (p<0.001), haemodialysis development (p<0.001), and inversely correlated with the use of mycophenolate mophetil (p<0.001); mortality was positively correlated with renal dysfunction pretransplant (p=0.03),chronic kidney disease stage 4 (p=0.001), chronic kidney disease stage 5 (p<0.001) and inversely correlated with the use of tacrolimus (p=0.006). In conclusion orthotopic liver transplant recipients are disposed to renal complications that have a negative impact on survival of these patients.