Long-Term Consequences of Increased Activity of Urine Enzymes After Cardiac Surgery - A Prospective Observational Study.

Introduction: Cardiac surgery associated AKI (CSA-AKI) complicates recovery and may be associated with a greater risk of developing chronic kidney disease and mortality. The aim of this study was to assess long-term clinical consequences of transient increased activity of urinary enzymes after cardiac surgery (CS). Methods: An observational study was conducted in a group of 88 adult patients undergoing planned coronary artery bypass grafting (CABG), but all samples were obtained from 79 patients. The activity of urinary enzymes: N-acetyl-beta-glucosaminidase (NAG), arylsulfatase A (ASA) and beta-glucuronidase was evaluated in sequential urine samples. A comparative analysis of biochemical parameters was performed regarding the occurrence of acute kidney injury (AKI) defined by KIDGO at 24 hours, at day 30 and 5-years after the operation. Results: During the first 24 hours after CS AKI was diagnosed in 13 patients. A comparison of the activity of urinary enzymes in pre-defined time-points showed significant differences for ASA and NAG (post OP-sample p < 0.028 and p < 0.022; POD 1 sample p < 0.004 and p < 0.001 respectively). No patient had any biochemical or clinical features of kidney failure at day 30. In the AKI group kidney failure was diagnosed in 36% of patients within 5 years of follow-up as opposed to 5% in the no AKI group. The activities of tubular enzymes in urine reflect a general injury of kidney tubules during and after the operation. However, they are not ideal biomarkers for prediction of the degree of kidney injury and further poor prognosis of CS-AKI.

Translocation of Exogenous FGF1 and FGF2 Protects the Cell against Apoptosis Independently of Receptor Activation.

FGF1 and FGF2 bind to specific cell-surface tyrosine kinase receptors (FGFRs) and activate intracellular signaling that leads to proliferation, migration or differentiation of many cell types. Besides this classical mode of action, under stress conditions, FGF1 and FGF2 are translocated in a receptor-dependent manner via the endosomal membrane into the cytosol and nucleus of the cell. However, despite many years of research, the role of translocated FGF1 and FGF2 inside the cell remains unclear. Here, we reveal an anti-apoptotic activity of intracellular FGF1 and FGF2, which is independent of FGFR activation and downstream signaling. We observed an inhibition of cell apoptosis induced by serum starvation or staurosporine upon treatment with exogenous FGF1 or FGF2, despite the presence of highly potent FGFR inhibitors. Similar results were found when the tyrosine kinase of FGFR1 was completely blocked by a specific mutation. Moreover, the anti-apoptotic effect of the growth factors was abolished by known inhibitors of the translocation of FGF1 and FGF2 from the endosomes to the interior of the cell. Interestingly, FGF2 showed higher anti-apoptotic activity than FGF1. Since FGF2 is not phosphorylated by PKCδ and is present inside the nucleus longer than is FGF1, we speculated that the different activities could reflect their diverse nuclear export kinetics. Indeed, we observed that FGF1 mutations preventing binding to nucleolin and therefore phosphorylation in the nucleus affect the anti-apoptotic activity of FGF1. Taken together, our data indicate that the translocation of FGF1 and FGF2 protects cells against apoptosis and promotes cell survival.

Iron excretion in urine in patients with acute kidney injury after cardiac surgery.

BACKGROUND: Hemolysis during cardiopulmonary bypass may lead to acute kidney injury caused by an excessive amount of iron. The clinical usefulness of the measurement of total iron concentration in the urine with the use of the atomic absorption spectrometry method for early identification of patients with postoperative acute kidney injury is not well-established. OBJECTIVES: An observational, prospective study was conducted on a group of 88 pre-selected adult patients undergoing a planned coronary artery bypass grafting (CABG) procedure. MATERIAL AND METHODS: The amount and concentrations of total iron, creatinine and neutrophil gelatinaseassociated lipocalin (NGAL) were evaluated in urine samples. A comparative analysis of the evaluated biochemical parameters was performed in regard to the occurrence of acute kidney injury 48 h postoperatively. RESULTS: Patients in the acute kidney injury group presented more advanced age (p = 0.01), preoperative myocardial infarction (p = 0.02), diuresis reduction (p = 0.04), and lower total iron levels in the 48-hour urine sample (p = 0.01). There was no difference when considering iron concentration in single urine samples in the study group. CONCLUSIONS: The sole result of total iron concentration in single urine samples is unreliable for the diagnosis of acute kidney injury after cardiac surgery. Decreased excretion of iron in the urine seems to be an important additional element in the multifactorial pathogenesis of acute postoperative kidney failure.

Cardiac surgery related cardio-renal syndrome assessed by conventional and novel biomarkers - under or overestimated diagnosis?

INTRODUCTION: Serum creatinine is a 'gold standard' criterion of recognizing and staging of acute kidney injury (AKI) despite it being a suboptimal, delayed indicator. The interpretation of increased values of biomarkers imposes great difficulty regarding cardiac surgery procedures performed with cardiopulmonary bypass and may lead to under- or overestimated diagnosis. The aim of this study was to evaluate the clinical utility of the sole serum creatinine or urine neutrophil gelatinase-associated lipocalin (NGAL) concentration used for identification of patients with AKI after cardiac surgery. MATERIAL AND METHODS: A prospective observational study was conducted on a group of 88 adult patients undergoing a coronary artery bypass grafting procedure. Serum creatinine was evaluated on the day of the operation, and 24 and 48 h post-operatively. Urinary NGAL concentration was measured: immediately after and one hour after cardiopulmonary bypass, and 24 h from the beginning of the operation. We assessed features of kidney injury and 30-day and 5-year mortality. RESULTS: Patients in the AKI group diagnosed with creatinine level and urine output criteria presented more advanced age (p = 0.01), higher body mass index (p = 0.01) and preoperative myocardial infarction (p = 0.02). Elevation of NGAL level was observed in 5 of 13 cases with AKI, based on creatinine criteria and 4 of 75 cases without AKI. Within 5 years after the surgical procedure the recurrence of renal failure was 36% in the AKI group (with perioperative NGAL elevation in 2 cases only). CONCLUSIONS: In the cardiac surgery patients the diagnosis of AKI based on sole serum creatinine or urine NGAL concentration confirmed transient kidney injury. However, the clinical implications of these findings are insufficient for prediction of clinical outcome.

Clinical and Biochemical Characteristics of Brain-Dead Donors as Predictors of Early- and Long-Term Renal Function After Transplant.

OBJECTIVES: Organs from brain-dead donors are the main source of allografts for transplant. Comparisons between living-donor and brain-dead donor kidneys show that the latter are more likely to demonstrate delayed graft function and lower long-term survival. This study aimed to assess the effects of various clinical and biochemical factors of donors on early- and long-term renal function after transplant. MATERIALS AND METHODS: We analyzed data from kidney recipients treated between 2006 and 2008 who received organs from brain-dead donors. Data from 54 donors and 89 recipients were analyzed. RESULTS: No relation was observed between donor sodium concentration and the presence of delayed graft function. Donor height was positively correlated with creatinine clearance in recipients in the 1 to 3 months after renal transplant. Donor diastolic blood pressure was negatively correlated with estimated glomerular filtration rate throughout the observation period. Donor age was negatively correlated with the allograft recipient's estimated glomerular filtration rate throughout 4 years of observation. Donor estimated glomerular filtration rate was positively correlated with that of the recipient throughout 3 years of observation. CONCLUSIONS: The results of this study indicate that various factors associated with allograft donors may influence graft function.

Urinary IL-8 is a marker of early and long-term graft function after renal transplantation.

In this study, we examined whether the IL-8 content of urine sampled on day 1 and day 14 after renal transplantation is a marker of early and long-term renal function. Moreover, we assessed whether its concentration is positively correlated with the matrix metalloproteinase-9 (MMP-9) content of urine sampled on day 1 and day 30 and 12 months after renal transplantation. Our analysis covered 87 patients who underwent a kidney transplant. The patients were observed for an average of 30 months (12-60 months). The IL-8 concentration determined on day 1 was significantly negatively correlated with creatinine clearance early after renal transplantation (on days 1, 7, 14 and 30), as well as during long-term observations. IL-8 concentration in urine sampled on day 1 and day 14 was higher in patients demonstrating DGF than in those without DGF. No relationship was found between IL-8 content and cold ischaemia time. MMP-9 activity determined on day 1 and month 3 after renal transplantation was positively correlated with the IL-8 content determined in urine sampled on day 1, Rs = +0.32, p < .05 and Rs = +0.31, p < .05, respectively. The results of this study suggest that a high IL-8 content in urine sampled on day 1 after renal transplantation is an unfavourable marker of early and long-term (years-long) graft function. A high IL-8 content in urine sampled on day 1 after renal transplantation was positively correlated with the activity of metalloproteinase-9 in urine. This proves that both of these chemokines cooperate in ischaemia-reperfusion injuries in transplanted kidneys.

Activity of urine arylsulfatase A in brain­dead graft donors is a predictor of early and late graft function.

OBJECTIVE: Human lysosomal arylsulfatase A (ASA) is a member of the sulfatase family. Arylsulfatase A is required to degrade sulfatides. Sulfatides occur in the myelin sheets of the central and peripheral nervous system. In this study we evaluated the urine activity of lysosomal enzyme arylsulfatase A in brain­dead donors as a marker and predictor of short - and long­term renal allograft function. PATIENTS/METHODS: We analyzed data from kidney recipients who received organs from brain­dead donors. Data from 40 donors and 68 recipients were analyzed. RESULTS: Urine activity of arylsulfatase A in graft donors correlated positively with creatinine clearance in graft recipients after transplantation: significantly after 30 days (Rs=0.38, p=0.004) and after 3 years (Rs=0.38, p=0.03), and with borderline significance after 14 days (Rs=0.25, p=0.08) and after one year (Rs=0.23, p=0.07). CONCLUSIONS: The results of this study suggest that arylsulfatase A has a protective effect on kidney allograft, and the urine activity of this enzyme in kidney donors correlates positively with graft function.

Effect of Immunosuppressive Therapy on Proteinogram in Rats.

BACKGROUND It has been observed that the use of immunosuppressive drugs in patients after transplantation of vascularized organs may be associated with changes in the concentration of certain fractions of plasma proteins. The concentration of these proteins was correlated with an increased risk of occurrence of stage 3 chronic kidney disease (CKD). This article examines the effect of the most commonly used immunosuppressive drugs on the concentration of plasma proteins in Wistar rats. MATERIAL AND METHODS The study involved 36 rats grouped according to the immunosuppressive regimen used (tacrolimus, mycophenolate mofetil, cyclosporine A, rapamycin, and prednisone). The rats in all study groups were treated with a 3-drug protocol for 6 months. The treatment dose was adjusted based on available data in the literature. No drugs were administered to the control group. The rats were sacrificed and blood samples collected to determine the concentration of plasma proteins using electrophoresis technique. RESULTS Statistically significant differences were observed between protein concentrations within the studied groups. The differences related to the proteins with masses of 195 kDa, 170 kDa, 103 kDa, and 58 kDa. CONCLUSIONS (1) Immunosuppressive drugs caused changes in the proteinogram of plasma proteins. (2) The strongest effect on rat plasma proteins was exerted by a regimen based on rapamycin. Intermediate, weak, and weakest effects were observed in regimens based on cyclosporine A, tacrolimus, and mycophenolate mofetil, respectively.

Urinary Metalloproteinases-9 and -2 and Their Inhibitors TIMP-1 and TIMP-2 are Markers of Early and Long-Term Graft Function After Renal Transplantation.

BACKGROUND/AIMS: Renal ischemia-reperfusion (I-R) injury (IRI) is an inseparable feature of organ transplantation and may have a negative impact on the graft, its function and survival. Acute tubular necrosis, which is reversible thanks to the regenerative capacity of renal tubular epithelial cells, is the main cause of acute renal failure secondary to IRI. MMP-2 and MMP-9 are proteolytic enzymes involved in digesting proteins that are components of the extracellular matrix (ECM) and the basement membrane of the nephrons. This way post-reperfusion MMP activation allows the inflammatory process to spread. METHODS: In our studies, we focused on identifying whether the concentrations of MMP-2 and MMP-9 and their natural inhibitors TIMP-1 and TIMP-2 in urine sample at day 1 and day 30 as well as after 12 months following renal transplantation are markers of early and long-term renal function during meanly five-years observation. Moreover, in urine sampled at months 6 and 12 after renal transplantation, we determined the content of TGF-ß as a graft fibrosis indicator. RESULTS: MMP-9 concentration in the early post-transplant period is a major marker of early and long-term function of the transplanted kidney. Its increased concentration was correlated with lesions related to tubular atrophy and fibrosis in renal biopsies performed at months 3 and 12 after transplantation. Its concentration is correlated with TGF-ß content in a later period. CONCLUSIONS: TIMP-1 and-2 are primarily markers of an early function of the transplanted kidney. Early post-transplant concentration of MMP-2 is a marker of proteinuria in early and long-term post-transplant periods.

Identification of new FGF1 binding partners-Implications for its intracellular function.

Besides its classical mode of action through activation of specific receptors at the cell surface, fibroblast growth factor 1 (FGF1) can also cross the cellular membrane and translocate into the cytosol and further to the nucleus. The mechanism of this translocation is described partially, but the role of FGF1 inside the cell remains unknown. The aim of our work was to identify novel binding partners of FGF1 to predict its intracellular functions. We combined three methods of identification of such partners based on different principles: yeast two-hybrid screen and mass spectrometry (MS) analysis of complexes obtained by Tandem Affinity Purification (TAP) or by co-precipitation from cell lysate using recombinant FGF1. Altogether, we identified twenty novel intracellular proteins interacting with FGF1. For selected proteins, their direct interaction with FGF1 was confirmed by pull-down assays and SPR measurements. Interestingly, half of the proteins found are involved in processes related to cell viability, such as apoptosis, cell proliferation, and cell cycle regulation. Thus, our study indicates that the role of intracellular FGF1 is to protect the cell against stress conditions by providing an additional signal for cell survival, independently of receptor-activated signaling cascades.

Urinary excretion of brush-border enzymes of the proximal renal tubules in pregnant women with hypertensive disorders.

OBJECTIVES: The aim of our study was to evaluate urinary excretion of three brush border enzymes: gamma-glutamyl transferase, alanine aminopeptidase, and leucyl aminopeptidase in pregnant women with various types of hypertensive disorders. MATERIAL AND METHODS: The study included 120 pregnant women, further subdivided into four groups: 41 women at ≥ 20 weeks gestation with gestational hypertension, 28 women > 20 weeks of pregnancy with preeclampsia, 21 women with chronic hypertension identified > 20 weeks of pregnancy and 30 healthy pregnant controls. RESULTS: No significant differences in urinary levels of all three of the brush border enzymes were found between the groups. Also, there was no correlation between enzyme concentration in the urine and blood pressure values in any of the analyzed groups of pregnant women. CONCLUSIONS: The obtained results suggest no damage to the brush border of the proximal kidney tubules in the early stages of disorders associated with increased blood pressure during pregnancy.

The impact of hemodialysis on erythrocyte membrane cytoskeleton proteins.

BACKGROUND: Hemodialysis (HD) is one of the methods of renal replacement therapy, but it also contributes to an increase in oxidative stress. Hemodialysis leads to changes in the erythrocyte cytoskeleton structure, whilst the presence of glucose in the dialysis fluid which activates the pentose phosphate pathway contributes to the intensification of oxidative stress. Available literature lacks reports on the effect of glucose in the dialytic fluid on the composition of proteins of the cell membrane cytoskeleton. MATERIAL/METHODS: Red blood cells for this analysis were collected from patients with chronic renal failure treated with hemodialysis using both glucose-containing and glucose-free dialysis fluid. Following the preparation of membranes, the electrophoretic separation of proteins was performed in denaturing conditions according to Laemmli. The level of tryptophan in membranes was determined by spectrofluorimetry, whilst the activity of glucose-6-phosphate dehydrogenase was determined by measuring the reduction of oxidated NADP. RESULTS: Hemodialysis in both groups of patients resulted in a statistically significant reduction of tryptophan as an oxidative stress indicator when compared to the control group. Moreover, the activity of glucose-6-phosphate dehydrogenase in the group of patients was higher than in the control group, and following the HD procedure it decreased, which may have been caused by a reduced concentration of dialyzed glucose. The HD procedure affects the structure of the erythrocyte membrane cytoskeleton, which is reflected in the concentration changes in individual proteins and in their mutual relationships corresponding to vertical and horizontal interactions stabilizing the structure of the erythrocyte membrane cytoskeleton. These changes may contribute to the shortening of cell lifespan.

[Nutritional status of patients undergoing peritoneal dialysis]. / Analiza stanu odzywienia pacjentów poddawanych dializie otrzewnowej.

INTRODUCTION: The main causes of death in patients undergoing dialysis are cardiovascular diseases. Their presence is related to the nutritional status of patients treated with peritoneal dialysis, and has a predicted value in this kind of patient. Long-term therapy entails unfavourable changes, from which a clinically significant complication is protein-energy malnutrition and intensification of inflammatory processes. The aim of the study was to assess the nutritional status of patients with chronic kidney disease treated with peritoneal dialysis based on anthropometric, biochemical parameters analysis, a survey, as well as the determination of changes in measured parameters occurring over time. MATERIAL AND METHODS: The study involved 40 people undergoing peritoneal dialysis (PD) and 30 healthy people. For dialyzed patients testing material was collected twice, every 6 months. Proteins, albumins, prealbumins, C-reactive protein and glucose levels were measured. Anthropometric measurements included body height, body weight, triceps skinfold and subscapular skinfold thickness. Body mass index (BMI) value and exponent of tissue protein source were calculated. The examined patients completed the questionnaire, which included, among other factors, the daily intake of nutrients, and lifestyle information. RESULTS: During the 6 month observation of the PD group a stastically significant increase in the energy value of intake food and amount of calories intake from carbohydrates was found. Analysis of nutritional status dependent on the BMI showed that overweight and obese patients are characterized by higher concentrations of the C-reactive protein and glucose, as well as lower concentrations of prealbumin compared to patients with normal body weight. At the same time, the energy value of food and the amount of protein in the group with BMI > 25 were smaller than in the other groups. During the 6 month observation a decrease the concentration of prealbumin and an increase in C-reactive protein in BMI > 25 group were observed. CONCLUSIONS: The nutritional status of all patients undergoing peritoneal dialysis was abnormal, which was not reflected by BMI. In overweight and obese patients increased changes over time were observed. This suggests the occurrence of protein-energy malnutrition.

The effect of immunosuppressive therapy on renal cell apoptosis in native rat kidneys.

AIM: To analyse the impact of the most commonly used immunosuppressive drugs on the occurrence of apoptosis in the native kidneys of Wistar rats. METHOD: The study involved 36 rats. the animals being grouped according to the immunosuppressive regimen used (tacrolimus, mycophenolate mofetil, cyclosporine A, rapamycin and prednisone). The rats in all study groups were treated with a 3-drug protocol for 6 months. The medication dose was adjusted based on available literature data. No drugs were administered to the control group. The rats were then killed. Autopsies of all animals were performed and the kidneys were isolated for histopathology (HE + PAS). To assess cell apoptosis the TUNEL reaction was performed. Blood trough levels of immunosuppressive drugs as well as the parameters of peripheral blood were determined. RESULTS: 1. In rats treated with cyclosporine A distal nephron tubules were characterised by more pronounced apoptosis. 2. In tacrolimus-treated rats a lower intensity of apoptosis was found in the distal tubules. 3. In rapamycin-treated rats the apoptosis was inhibited both in the distal and proximal nephron tubules. 4. In MMF treated rats intense apoptosis was observed in the proximal nephron tubules. 5. There were no significant changes in renal histopathology (HE + PAS). CONCLUSIONS: The apoptosis in nephron tubules caused by immunosuppressive therapy is not accompanied by any histopathological changes (eg fibrosis, inflammation, tubular atrophy, vacuolation of the tubular cells) in light microscopy.

Effects of immunosuppressive treatment on protein expression in rat kidney.

The structural proteins of renal tubular epithelial cells may become a target for the toxic metabolites of immunosuppressants. These metabolites can modify the properties of the proteins, thereby affecting cell function, which is a possible explanation for the mechanism of immunosuppressive agents' toxicity. In our study, we evaluated the effect of two immunosuppressive strategies on protein expression in the kidneys of Wistar rats. Fragments of the rat kidneys were homogenized after cooling in liquid nitrogen and then dissolved in lysis buffer. The protein concentration in the samples was determined using a protein assay kit, and the proteins were separated by two-dimensional electrophoresis. The obtained gels were then stained with Coomassie Brilliant Blue, and their images were analyzed to evaluate differences in protein expression. Identification of selected proteins was then performed using mass spectrometry. We found that the immunosuppressive drugs used in popular regimens induce a series of changes in protein expression in target organs. The expression of proteins involved in drug, glucose, amino acid, and lipid metabolism was pronounced. However, to a lesser extent, we also observed changes in nuclear, structural, and transport proteins' synthesis. Very slight differences were observed between the group receiving cyclosporine, mycophenolate mofetil, and glucocorticoids (CMG) and the control group. In contrast, compared to the control group, animals receiving tacrolimus, mycophenolate mofetil, and glucocorticoids (TMG) exhibited higher expression of proteins responsible for renal drug metabolism and lower expression levels of cytoplasmic actin and the major urinary protein. In the TMG group, we observed higher expression of proteins responsible for drug metabolism and a decrease in the expression of respiratory chain enzymes (thioredoxin-2) and markers of distal renal tubular damage (heart fatty acid-binding protein) compared to expression in the CMG group. The consequences of the reported changes in protein expression require further study.

N-acetyl-beta-glucosaminidase urine activity as a marker of early proximal tubule damage and a predictor of the long-term function of the transplanted kidneys.

INTRODUCTION: Ischaemia-reperfusion injury (IRI) is a factor leading to the damages of the transplanted kidney, what affects mainly the proximal tubules. Early monitoring of tubule damage can be an efficient tool to predict the allograft dysfunction. Present in proximal tubules, N-acetyl-beta-glucosaminidase (NAG) is a lysosomal enzyme whose excretion rises as a result of IRI or acute rejection. The aim of this study was to monitor the NAG urine activity to evaluate the early proximal tubule damage, and to try to predict the long-term function of the transplanted kidney. MATERIAL AND METHODS: The study enrolled 87 Caucasian renal transplant recipients (61.7% males, 38.3% females, mean age 45.56±14.34 years). Urine samples were collected for NAG and creatinine analysis on the 1st day after transplantation, and then in the 3rd and 12th month. Protocol biopsies were performed in the 3rd and 12th month. RESULTS: A significant positive correlation between NAG urine activity in the 3rd month after transplantation and creatinine concentration on the 14th (p=0.004) and 30th day (p=0.05), in the 3rd month (p=0.009) and after the 1st (p=0.005) and 2nd year (p=0.003) was observed. A statistically significantly higher urinary NAG activity in samples collected in the first 3 days and in the 3rd month after transplantation among patients with DGF (p=0.006 and p=0.03 respectively) was found. There was a significant positive correlation between NAG urine activity in the 3rd month and the grade of tubular atrophy in specimens collected in the 3rd (p=0.03) and 12th (p=0.04) month. CONCLUSIONS: Monitoring of NAG urine activity is useful in the evaluation of early proximal tubule damage and predicting the long-term function of the transplanted kidneys.

Urinary lysosomal enzyme excretion in pregnant women with hypertensive disorders.

BACKGROUND: The authors assessed proximal renal tubular dysfunction and/or damage in pregnant women with various types of hypertension by measuring the three urinary lysosomal enzyme levels: N-acetyl-ß-d-glucosaminidase (NAG), arylsulfatase A and ß-glucuronidase. METHODS: The study consisted of 120 pregnant women divided into four groups: 41 women in 20th week of gestation or more, with pregnancy-induced hypertension (PIH group), 28 pregnant women after 20 weeks of pregnancy with pre-eclampsia (PE group), 21 pregnant women with chronic hypertension, identified before 20th week of pregnancy (CH group) and 30 healthy, pregnant women (healthy controls (HC) group). RESULTS: Statistical analysis showed significantly higher levels of all the three of lysosomal enzymes in the urine of patients with PE compared with the healthy pregnant women, pregnant women with PIH and the ones with chronic hypertension. Additionally, significantly higher values of NAG were found in the group of pregnant women with PIH compared with healthy pregnancies. No correlation was found between the concentration of enzymes in urine and values of blood pressure in any of the analyzed groups of pregnant women. CONCLUSIONS: The authors conclude that higher values of all the studied enzymes in PE group, in the comparison with the other groups, indicate proximal tubular damage at the cellular level. The lack of correlation between the concentration of lysosomal enzymes and blood pressure suggests that the damage to these parts of kidney is complex. In addition, mechanisms other than hypertension realizing intracellular enzymes may be involved in this process.

Nucleolin regulates phosphorylation and nuclear export of fibroblast growth factor 1 (FGF1).

Extracellular fibroblast growth factor 1 (FGF1) acts through cell surface tyrosine kinase receptors, but FGF1 can also act directly in the cell nucleus, as a result of nuclear import of endogenously produced, non-secreted FGF1 or by transport of extracellular FGF1 via endosomes and cytosol into the nucleus. In the nucleus, FGF1 can be phosphorylated by protein kinase C δ (PKCδ), and this event induces nuclear export of FGF1. To identify intracellular targets of FGF1 we performed affinity pull-down assays and identified nucleolin, a nuclear multifunctional protein, as an interaction partner of FGF1. We confirmed a direct nucleolin-FGF1 interaction by surface plasmon resonance and identified residues of FGF1 involved in the binding to be located within the heparin binding site. To assess the biological role of the nucleolin-FGF1 interaction, we studied the intracellular trafficking of FGF1. In nucleolin depleted cells, exogenous FGF1 was endocytosed and translocated to the cytosol and nucleus, but FGF1 was not phosphorylated by PKCδ or exported from the nucleus. Using FGF1 mutants with reduced binding to nucleolin and a FGF1-phosphomimetic mutant, we showed that the nucleolin-FGF1 interaction is critical for the intranuclear phosphorylation of FGF1 by PKCδ and thereby the regulation of nuclear export of FGF1.

Gamma-glutamyl transpeptidase as the marker of kidney graft function.

BACKGROUND: Gamma-glutamyl transpeptidase (GGT) is a glycoprotein of the external surface of various cell types. The activity of GGT has been observed in cells and tissues with secretory activity, such as the proximal tubular cells in kidneys. GGT also plays an important pro-oxidant role, stimulating the generation of hydroxyl radicals, and increases membrane lipid peroxidation. OBJECTIVES: In this study we examined whether the monitoring of GGT activity in urine may be a prognostic factor of kidney allograft function. The study enrolled 107 Caucasian renal transplant recipients. MATERIAL AND METHODS: Urine samples were collected for GGT and creatinine analysis on the 1st day after transplantation, and then in the 3rd and 12th month. RESULTS: Higher urine GGT activity in the 3rd month after transplantation was associated with significantly higher risk of graft failure (HR=1.063 per each U/g creatinine; 95%Cl:1.004-1.127; p=0.037) in the Cox proportional hazards model. Moreover, there were positive correlations between urine GGT and the grade of interstitial fibrosis (Rs=0.64, p=0.01) and tubular atrophy (Rs=0.54, p=0.056) in specimens collected in the 3rd month after transplantation. CONCLUSIONS: Our results suggest that higher urine GGT activity in the 3rd month after transplantation may be a prognostic factor of graft failure.

Adipokines and parameters of peritoneal membrane transport in newly started peritoneal dialysis patients.

AIM: Adiponectin and leptin are two adipokines playing important roles in the regulation of body weight, appetite, carbohydrate and lipid metabolism. In patients with chronic kidney disease (CKD) adipokines accumulate in serum due to reduced renal clearance. Since adipokines have pleiotropic actions, the adipokine balance may have an impact on peritoneal membrane transport. The aim of this study was to assess whether serum adiponectin and leptin levels were related to peritoneal transport and residual renal function (RRF) in newly started peritoneal dialysis patients. METHODS: 25 clinically stable patients, 4 to 6 weeks after the onset of PD, were included in the study. For each patient clinical and laboratory data were reviewed and standard PET test was performed. Serum adiponectin and leptin concentrations were determined and leptin/adiponectin (L/A) ratio was calculated. RESULTS: Serum adiponectin correlated negatively with weight, BMI and glucose concentration. Serum leptin and L/A ratio correlated positively with BMI. Serum adiponectin correlated positively with dialysate to plasma (D/P) creatinine ratio and ultrafiltration in PET test. Serum leptin level and L/A ratio correlated strongly negatively with peritoneal creatinine clearance. CONCLUSIONS: Serum adiponectin concentration is positively associated with baseline solute transport. Leptin concentration and L/A ratio are negatively associated with dialysis adequacy in newly started PD patients.