Serum Vitamin E Levels in Patients with Chronic Renal Failure

27 patients with chronic renal failure, 21 patients on chronic intermittend dialysis treatment and 27 healthy controls were tested for serum level of vitamin E estimated spectrophotometrically. Both patient groups had significant higher mean values (12.1 ± 1.2 and 7.2 ± 0.8 μg/ml respectively) in comparison with normal controls (4.6 ± 0.7 μg/ml). No correlation was found to serum creatinine, hematologic values, protein and lipoprotein concentration, nor to mode and duration of treatment regimes. Vitamin E was not extracted from blood throughout dialysis.

Under normal conditions of conservative or dialysis treatment of chronic renal failure patients vitamin E seems not to be a factor concerning uremic symptoms and there is no need for supplementation.

Interpretation erhöhter D-Dimerkonzentration

Hintergrund: Die Bestimmung der D-Dimerkonzentration ist unverzichtbarer Bestandteil der Diagnostik thromboembolischer Erkrankungen (z. B. Beinvenenthrombosen, Lungenembolien). D-Dimere sind als Spaltprodukte des Fibrins bei fibrinolytischen Prozessen im Rahmen der reaktiven Fibrinolyse nach thrombotischen Prozessen nachweisbar. Fragestellung: In der klinischen Praxis bestehen immer wieder Probleme bei der Interpretation erhöhter D-Dimerkonzentrationen, vor allem, wenn keine thromboembolische Erkrankung vorliegt. Vor der Einleitung einer weiterführenden (meist bildgebenden) Diagnostik sollen andere Ursachen für die erhöhten D-Dimerwerte (z. B. Schwangerschaft, Tumorerkrankung, systemische entzündliche Erkrankung, fortgeschrittene Arteriosklerose) differenzialdiagnostisch berücksichtigt werden. Zusammenfassung: Die Bestimmung des D-Dimerkonzentration muss zielgerichtet bei thromboembolischen Erkrankungen erfolgen. Der Parameter ist jedoch ungeeignet als Screening-Verfahren im Rahmen der klinischen Routine. Gesichert ist sein hoher prädiktiv-negativer Wert zum Ausschluss einer Thrombose bzw. Lungenembolie bei negativem Testergebnis. Zahlreiche weitere Erkrankungen oder physiologische Zustände führen ebenfalls zu erhöhter D-Dimerkonzentration, so dass ein positiver D-Dimer-Test nicht die Basis zur Diagnose einer Thromboembolie sein darf.

Vitamin status in patients with chronic renal failure

Many factors complicate the effort for a recommendation on individual vitamin requirements in CRF. On the basis of our present incomplete knowledge about the handling of vitamins in uremia, suggestions for appropriate supplementation only of water-soluble vitamins are given. Patients with advanced CRF without dialysis treatment should receive daily supplements of vitamin B6 (5 mg), ascorbic acid (70-100 mg), and the normal recommended daily allowance of the other water-soluble vitamins in addition to the vitamin intake from the diet. We give folic acid only in patients taking antifolate drugs or in combination with iron in iron deficiency state and anemia (1 tablet of Folicombin contains 0.5 mg folic acid and 0.4 g elemental iron). There is still a pressing need for more data on the vitamin status, on vitamin requirements, and on long-term effects of vitamin administration in CRF.

[Medical therapy of urinary tract infection]

Urinary tract infections (UTI) are the most common bacterial infectious diseases seen in the community, in most cases caused by E. coli. The treatment strategy differs depending on localization (lower vs. upper UT), acute uncomplicated vs. complicated infection, as well as for chronic disease and asymptomatic bacteriuria, the known or susceptible causative uropathogen with the (local) resistance pattern and the morbidity of the patient. There is a considerable worrying increase in the resistance rate of E. coli to TMP/SMX, quinolones and others. Most patients with uncomplicated, in the community acquired UTI are treated safely and effectively as out-patients. The available data support a short-course therapy with 3 days as the current standard therapy for lower UTI, but with a 7-14 days treatment for upper and complicated UTI. Recurrent UTI is best managed by low-dose antimicrobial prophylaxis for 3-6 (12 ore more) months. Besides that, new approaches to preventive strategies must prove their value in specific patient groups.

DNA Fragmentation in Acute and Chronic Rejection After Renal Transplantation

Acute and chronic rejections are important denominators for the long-term function of renal grafts. One important indicator of cell damage is enzymatic DNA fragmentation. To investigate possible mechanisms, the rate of DNA fragmentation (TUNEL staining), the expression of tissue transglutaminase II (a marker of advanced DNA damage), and 8-hydroxy-2'-deoxyguanosine (8-OhdG), an indicator of oxidative injury of nucleic acids, were studied by immunohistochemistry. Semithin sections of renal biopsies revealed 23 patients to show acute interstitial rejections (Banff 97 IA, IB); eight patients, acute vascular rejection (Banff 97 IIA, IIB); and 20 patients, chronic allograft nephropathy (Banff 97 I to III). Correlations were calculated between apoptotic cells and serum creatinine at the time of biopsy and after 6 months. In acute rejection, the proximal tubular cells were apoptotic, particularly in regions with mononuclear infiltrates. In consecutive sections, these apoptotic tubular cells also showed damage by reactive oxygen species (positive 8-OhdG staining). Patients with acute interstitial rejection revealed the highest number of tubular DNA fragmentation (14.9 +/- 10.3) versus chronic allograft nephropathy (9.2 +/- 5.6) as TUNEL-positive cells per 80,000 micro m(2) (P < .05). Patients with acute vascular rejection showed a low degree of tubular apoptosis (6.8 +/- 5.1). There was no significant difference in glomerular DNA fragmentation between acute interstitial and chronic rejections: acute interstitial rejection = 7.1 +/- 5.9 versus chronic allograft nephropathy=6.1 +/- 3.9 TUNEL-positive cells per 80,000 micro m(2). There was a significant negative correlation between the degree of tubular (P < .01) and glomerular (P < .05) apoptosis and the serum creatinine at the time of biopsy as well as after 6 months in all patients irrespective of the Banff class. However, there was heterogeneity in the correlation between renal function and the degree of apoptosis in the glomerular and tubular compartments in the various Banff classes. A positive correlation (P < .01) was observed between the degree of tubular apoptosis and serum creatinine at 6 months after biopsy among patients with acute vascular rejection (Banff 97 IIA, IIB). The present data revealed a high degree of tubular DNA fragmentation associated with oxidative stress in acute interstitial rejection. Nevertheless, apoptosis did not generally negatively influence future renal function and may be important to clear proliferating cells. Apoptosis may also play a different pathophysiological role depending on the type of rejection.

DNA Fragmentation in Chronic Glomerulonephritis: An Immunohistological Analysis

BACKGROUND

Experimental data suggest that apoptosis plays an important pathophysiological role in glomerulonephritis by restoring tissue structure after proliferation of intrinsic renal cells and infiltration of leukocytes. Relatively little is known of apoptosis in human glomerulonephritis, particularly in predicting renal function during follow-up.

METHODS

In order to colocalize different markers for cell damage in renal tissue from patients with different forms of glomerulonephritis (GN), a series of semithin sections from 34 kidney biopsies were studied retrospectively. Normal kidney from a nephrectomy specimen with a small renal adenocarcinoma served as a control. DNA fragmentation, expression of tissue transglutaminase II, BAX and BCL-2 were visualized immunohistochemically. In some renal biopsies, immunohistochemical staining for activated caspase 3 was performed. Proinflammatory markers (C-reactive protein, leukocytes), serum creatinine, creatinine clearance, total proteinuria, albuminuria, alpha(1)-microglobulin and IgG excretion were determined at the time of biopsy. Serum creatinine and total proteinuria were assessed 6 and 12 months after renal biopsy.

RESULTS

Nuclei with different degrees of DNA fragmentation were mainly found in epithelial cells of tubules, but also in glomerular cells, regardless of the form of GN studied. Transglutaminase II expression was found only in cells with a strong staining for DNA fragmentation. DNA fragmentation localized to glomerular cells was more pronounced in proliferative than in non-proliferative forms of GN, being most abundant in patients with rapid progressive GN. Staining for activated caspase 3 in selected biopsies confirmed the presence of apoptosis. BAX and BCL-2 staining was detected within the same cells, but exhibited a different intracellular distribution. In proliferative GN, the extent of DNA damage in tubular epithelial cells significantly corresponds with the concentration of serum creatinine (p < 0.04) and with urinary excretion of alpha(1)-microglobulin (p < 0.01) at the time of biopsy. A significant correlation (p < 0.01) was seen between glomerular DNA fragmentation and follow-up total proteinuria 12 months after biopsy for proliferative forms of GN. The damaged glomerular area (e.g. mesangial sclerosis) significantly correlated with DNA fragmentation in proliferative, but not in nonproliferative GN at the time of biopsy. Furthermore, glomerular damaged showed a significant correlation with tubular DNA damage in proliferative GN.

CONCLUSION

In glomerular cells, apoptosis may be important for the clearance of proliferating cells whereas in tubules, cell damage showed dependence on the degree of tubular injury mediated by inflammation and/or proteinuria. Although the degree of apoptosis in tubular cells correlates with serum creatinine in proliferative GN at the time of biopsy, it is of limited use to predict future renal function.

[Recurrent urinary tract infections in women. Virulence of pathogens and host reaction]

The interactions of host-specific and microbial factors are responsible for recurrent urinary tract infections (rUTI). The anatomical properties of the female urogenital tract favor colonization by uropathogens. Local factors such as glucose concentration of the urine, stability of the lactobacilli population, the influence of estrogens, the activity of Tamm-Horsfall protein or of defensins, and disturbance of the systemic defense mechanisms dictate the course of an infection. The most prominent uropathogen is E. coli. It expresses various virulence factors including adhesions, toxins, iron uptake systems, and a capsule. It is still unclear if there are virulence factors characteristic for E. coli strains causing rUTI. The formation of intracellular reservoirs by invasion of uroepithelial cells by E. coli could be another, as yet little noticed cause for rUTI. Therefore, in cases of rUTI the application of intracellularly active antibiotics should be considered.

Effect of L-methionine supplementation on plasma homocysteine and other free amino acids: a placebo-controlled double-blind cross-over study

OBJECTIVE

The essential amino acid L-methionine is a potential compound in the prophylaxis of recurrent or relapsing urinary tract infection due to acidification of urine. As an intermediate of L-methionine metabolism, homocysteine is formed. The objective was to study the metabolism of L-methionine and homocysteine, and to assess whether there are differences between patients with chronic urinary tract infection and healthy control subjects.

DESIGN

A randomized placebo-controlled double-blind intervention study with cross-over design.

SETTING

Department of Nutritional Physiology, Institute of Nutrition in cooperation with the Department of Internal Medicine III, Friedrich Schiller University of Jena, Germany.

SUBJECTS

Eight female patients with chronic urinary tract infection and 12 healthy women (controls).

INTERVENTIONS

After a methionine-loading test, the volunteers received 500 mg L-methionine or a placebo three times daily for 4 weeks.

MAIN OUTCOME MEASURES

Serum and urinary concentrations of methionine, homocysteine, cystathionine, cystine, serine, glycine and serum concentrations of vitamin B12, B6 and the state of folate.

RESULTS

Homocysteine plasma concentrations increased from 9.4+/-2.7 micromol/l (patients) and 8.9+/-1.8 micromol/l (controls) in the placebo period to 11.2+/-4.1 micromol/l (P=0.031) and 11.0+/-2.3 micromol/l (P=0.000), respectively, during L-methionine supplementation. There were significant increases in serum methionine (53.6+/-22.0 micromol/l; P=0.003; n=20) and cystathionine (0.62+/-0.30 micromol/l; P=0.000; n=20) concentrations compared with the placebo period (33.0+/-12.0 and 0.30+/-0.10 micromol/l; n=20). Simultaneously, renal excretion of methionine and homocysteine was significantly higher during L-methionine intake.

CONCLUSIONS

Despite an adequate vitamin status, the supplementation of 1500 mg of L-methionine daily significantly increases homocysteine plasma concentrations by an average of 2.0 micromol/l in patients and in control subjects. An optimal vitamin supplementation, especially with folate, might prevent such an increase.

Correlation between blood group phenotype and virulence properties of Escherichia coli in patients with chronic urinary tract infection

A predisposition to urinary tract infection (UTI) is associated with the expression of P1 as well as the presence of ABO blood group antigen on the boundary layer and with the secretor state. Infectious microorganisms interfere with specific molecules on epithelial cells, these are antigens of the P and ABO blood group system. The blood group phenotype was examined in 53 women (age 42 +/- 12 years) with chronic non-obstructive UTI. The diagnosis was established on the basis of clinical history as well as clinical laboratory and radiological findings. The ABO phenotype and the P1 antigen were analysed by anti-A and anti-B as well as anti-P1 serum. The Lewis phenotyping was performed by incubating erythrocytes with anti-Le(a) and anti-Le(b) serum. In all patients, the blood group status were investigated. The proportion of persons with B-phenotype was 23% (the incidence of this feature in the German population is 14.5%). P1 antigen was found in 76% patients. In comparison with P1 antigen-negative individuals, P1 antigen-positive persons have a longer disease history and suffer more frequently from symptomatic events as well as destructive renal changes. The Le (a)-antigen was detected in 82% and the Le (b)-phenotype was observed in 18% of patients. The blood group phenotypes (ABO, Lewis and P1 antigens) represent an interesting natural aspect of local defence system against the invasive efforts of uropathogens. Antigen structures on uroepithelial cells for example, the glycolipids of the P antigen, serve as receptors for adhesion of microorganisms.

Diabetes mellitus and dialysis

Diabetes mellitus is increasing, and in some countries is the single most important cause, for end-stage renal disease. In general, primarily elderly patients on renal replacement therapy, are not only affected by diabetes-related long-term complications, but also frequently with a wide range of co-morbidities. Apart from cardiac complications, the patients are subject to a wide range of vascular (i.e. peripheral vascular disease, stroke) and infectious complications. In the past this has been reflected by a relatively poor survival rate on dialysis, and minimized chances to obtain renal transplantation. Today, several renal replacement strategies are available, including the main 3: hemodialysis, peritoneal dialysis or kidney transplantation. For patients with diabetes mellitus, hemodialysis is the most commonly used therapy. Each dialysis unit should achieve an optimal dialysis adequacy represented by a single pool Kt/V of at least 1.2. The most important independent predictor of patient survival with hemodialysis treatment is age. Other factors related to complications are left ventricular hypertrophy, arterial hypertension, hypervolaemia and chronic anemia. Moreover, medial arterial calcification, malnutrition, gastrointestinal disorders and dialysis against low potassium dialysate are related to increased morbidity and mortality as well. An integral part of treatment is the availability of good vascular access. The survival rates of fistulas show a nearly twofold higher rate of failure for synthetic grafts compared with arteriovenous fistulas. The role of peritoneal dialysis in renal replacement therapy in patients with diabetic nephropathy is well established and used world-wide. Most patients with residual renal function start with continuous ambulatory peritoneal dialysis (CAPD), but automated peritoneal dialysis can also be used. An unresolved problem associated with CAPD is the glucose absorption and caloric intake. The optimum adjustment of blood glucose values is made more difficult. Death rates of diabetic patients on peritoneal dialysis remain higher than in non-diabetics. The changes in peritoneal membrane thickness and vascular alterations in relationship to the duration of dialysis are caused mainly by glucose and glucose degradation products, such as advanced glycation endproduct (AGEs). Therefore, new peritoneal dialysis solutions are needed to reduce the complications and to delay a long-time function of the peritoneal membrane. Peritonitis remains still the major cause of discontinuation of dialysis but there is no increased risk in diabetic patients. Nevertheless, an integrative care of end-stage renal disease patients with diabetic nephropathy should be offered to the patient, starting on peritoneal dialysis and switch to hemodialysis if problems arise. During the whole time patients should be kept on the renal transplantation waiting list.

[Interpretation of increased D-dimer values]

BACKGROUND

The determination of D-dimer concentration is an essential part in the diagnostic procedure of thromboembolic diseases, e.g. deep vein thrombosis, pulmonary embolism. D-dimers are the products of fibrin hydrolysis with elevated levels in fibrinolytic processes.

QUESTION

In the clinical practice problems exist in the interpretation of increased D-dimer concentrations, especially without thromboembolic disease. Before starting further expensive imaging diagnostics other reasons (i.e. pregnancy, neoplasma, systemic inflammatory disease, advanced arteriosclerosis) should be considered in differential diagnosis.

CONCLUSION

The determination of the concentration of D-dimers is involved in the diagnostic strategy in thromboembolic diseases. However, this parameter is not suited for routine screening. Its high predictive-negative value is proved for the exclusion of thrombosis or pulmonary embolism in case of negative test result. Since a range of diseases and physiological conditions lead to increased D-dimer values, a positive D-dimer result does not verify the diagnosis of thromboembolism.

Differential expression of b-chemokines MCP-1 and RANTES and their receptors CCR1, CCR2, CCR5 in acute rejection and chronic allograft nephropathy of human renal allografts

BACKGROUND

The beta-chemokines MCP-1 (CCL2) and RANTES (CCL5) have been shown to play important roles in acute renal transplant rejection (AR) and chronic allograft nephropathy (CAN). The potential relationship of expression of these chemokines, their chemokine receptors CCR1, CCR2, CCR5, and the cell populations of inflammatory infiltrate, histological and clinical diagnoses were investigated in biopsies at the time of AR and compared with biopsies of CAN.

METHODS

In 24 renal transplant biopsies with AR (n = 15) and CAN (n = 9), the expression of MCP-1 and RANTES, their receptors CCR1, CCR2, and CCR5 and the infiltration with monocytes/macrophages and T cells were studied.

RESULTS

As previously described, chemokine and chemokine receptor expression was found mainly in mononuclear cells infiltrating the interstitium and glomeruli. In the tubulointerstitial area and glomeruli the expression of MCP-1, RANTES, and their receptors correlated with an infiltration by monocytes/macrophages. Biopsies with CAN revealed a lower expression of MCP-1, RANTES, CCR1, CCR2 and CCR5 in tubulointerstitial cells, and a significantly lower infiltration with MRP14-positive monocytes/macrophages than biopsies with AR. In AR, MCP-1 and CCR1 showed a lower expression compared to RANTES, CCR2, and CCR5.

CONCLUSIONS

The positive correlation between chemokines and chemokine receptors and infiltrating leukocytes during acute rejection, the lower but detectable expression of MCP-1, RANTES, CCR1, CCR2 and CCR5 in CAN, and the differences in the quantity of expression between the different chemokines and chemokine receptors point to a complex regulation of chemokine expression in renal allografts. Since chemokines are not only involved in inflammation but also in tissue regeneration, this could have impact on the development of CAN.

Anti-C1q antibodies and antiendothelial cell antibodies in systemic lupus erythematosus ? relationship with disease activity and renal involvement

The aim of this study was to investigate the relationship between the presence and titre of antibodies against C1q (anti-C1q Ab) and disease activity and renal involvement in patients with systemic lupus erythematosus (SLE). Anti-C1q Ab were measured in 79 patients with SLE (70 women and 9 men; mean age 41.7 years; mean disease duration 8.4 years): 19 patients had active disease with lupus nephritis, 8 active disease without nephritis, 26 inactive disease with nephritis and 26 inactive disease without nephritis. Anti-dsDNA antibodies (EIA and immunofluorescence), antiendothelial cell antibodies (AECA) and complement levels (C3, C4, total haemolytic complement activity) were determined in parallel. Anti-C1q Ab were positive in 49%, anti-dsDNA Ab in 61% and AECA in 19% of the patients, respectively. Significantly higher titres of anti-C1q Ab were found in patients with active disease compared with those with inactive SLE ( P < 0.01). Serum levels of anti-C1q Ab showed a positive correlation with anti-dsDNA Ab and SLEDAI score ( P < 0.01) and a negative correlation with C3 ( P < 0.05), C4 ( P < 0.01) and CH50U ( P < 0.01). The presence of anti-C1q Ab was not different between patients with or without nephritis. In patients with ( P < 0.05) and without nephritis ( P < 0.01) the frequency of anti-C1q Ab was significantly higher in active patients compared with inactive patients. Both anti-C1q and anti-ds-DNA Ab were detectable in 74% of patients with active nephritis but only in 30% of all other patients ( P=0.001). None of the patients with active nephritis was negative for anti-C1q and anti-dsDNA Ab, whereas 37% of the patients without active nephritis were negative for both antibodies ( P < 0.01). Sensitivity, specificity, positive and negative predictive values for active lupus nephritis among SLE patients were 100%, 50%, 51.9% and 100% for anti-dsDNA Ab (EIA) and 74%, 70%, 57% and 89.4% for positive findings of both anti-dsDNA and anti-C1q Ab. The presence and titre of anti-C1q-Ab in SLE are related to disease activity. Absence of anti-dsDNA Ab excludes active nephritis; positive findings of both anti-dsDNA Ab and anti-C1q Ab are of relatively high specificity for active nephritis.

[Validity of iohexol clearance in patients with chronic renal failure and normal renal function in comparison to (99m)Tc-DTPA-clearance]

BACKGROUND AND OBJECTIVE

The most common method used for testing dynamic renal function is creatinine clearance, but it has some limitations, e. g. variable muscle mass and tubular secretion of creatinine. The use of radionuclides as an exact method is limited in terms of availability, cost and time needed for examination. We compared the plasma clearance of iohexol with the established (99m)Tc-diethylenetriaminepentaacetate acid (DTPA) clearance. The aim of the present study was to validate iohexol clearance as a simple and suitable method for measuring to determine GFR with a comparable sensitivity to radioisotopic methods.

METHODS

120 patients (49 females, 71 males), mean age of 56 (range 20 to 84) years with normal renal function and different stages of renal failure, mean creatinine clearance of 61.6 +/- 44,9 (range 1.8 - 181.1) ml/min/1.73 m2 received a bolus injection of 10 ml iohexol, a non-ionic low osmolar x-ray contrast medium. Using the one-compartment model, plasma samples were taken after 150, 240 and 480 minutes. The total plasma disappearance of iohexol was measured by x-ray fluorescence analysis and the clearance was calculated. The (99m)Tc-DTPA clearance was determined in accordance with a standard protocol.

RESULTS

A high correlation was found between the clearance of iohexol and (99m)Tc-DTPA (r = 0.95). The average deviation between Iohexol and (99m)Tc-DTPA clearance was 7.4 ml/min/1.73 m2. Allergic and nephrotoxic side effects were not observed.

CONCLUSION

Iohexol clearance is a valid method for measuring GFR in patients at any stages of renal failure. It is easy to perform and inexpensive.

The effects of prolonged physical exercise on renal function, electrolyte balance and muscle cell breakdown

BACKGROUND

Postexercise proteinuria, hematuria and changes in serum electrolyte balance as well as increased levels of plasma indicators for muscle leakage are believed to be transient and of benign character.

METHODS

A group of 51 healthy athletes took part in a 100 km race over 14.25 hours. All of them had to reach the finish together. Urine and blood samples were collected before (a) and immediately after running (b) as well as 6 hours after the race (c).

RESULTS

The serum concentrations of potassium (4.8 +/- 0.5 (a) vs. 4.0 +/- 0.3 (c) mmol/l), protein (73.1 +/- 5.2 (a) vs. 71.1 +/- 3.9 (c) g/l) and albumin (44.0 +/- 2.85 (a) vs. 42.9 +/- 2.8 (c) g/l) decreased significantly (p < 0.0001, p < 0.05, p < 0.05, respectively) but remained within physiological ranges. The serum sodium concentration decreased immediately after the race (136.9 +/- 4.5 (a) vs. 131.1 +/- 2.4 (b) micromol/l, p < 0.0001). The fractional sodium excretion decreased 6 hours, but not immediately after the race (0.78 +/- 0.59 (a) vs. 0.48 +/- 0.82 (c), p < 0.05). Myoglobin (31.8 +/- 6.9 (a), 291.5 +/- 197.2 (b) and 182.2 +/- 135.3 (c) microg/l, p < 0.0001) and creatine kinase (1.13 +/- 0.45 (a), 10.76 +/- 6.9 (b) and 9.46 +/- 15.5 (c) pmol/l, p < 0.0001) increased dramatically. Troponin I was also significantly increased at finish (0.0186 +/- 0.0121 (a) vs. 0.0213 +/- 0.0165 (b) ng/ml, p < 0.05) and positively correlated with myoglobin and creatine kinase, but remained far below the pathologic range. Serum creatinine and urea remained almost unchanged. Glucosuria and hematuria occurred 6 hours after the run in 9.1% and 6.8%, respectively. The erythrocytes examined by phase-contrast microscopy were not damaged in terms of dysmorphic cells. Glomerular-type proteinuria was found in 11.4% of the participants 6 hours after the race.

CONCLUSIONS

We conclude that long lasting, mild exertion is harmless for renal function, electrolyte balance and skeletal muscle as well as myocardial metabolism in healthy persons.

Determination of erythrocyte antioxidant capacity in haemodialysis patients using electron paramagnetic resonance

BACKGROUND

The increased oxidative stress of uraemia is caused both by an increased generation of oxygen-free radicals and a decrease of antioxidative forces. There are, however, conflicting data concerning disturbances of the radical-scavenging power of red blood cells (RBCs) in uraemic patients.

METHODS

The antioxidant capacities of the RBCs of 10 haemodialysis (HD) patients and 10 controls were examined after treatment with 0.324 mM tert-butylhydroperoxide (t-BOOH) in phosphate-buffered saline at 37 degrees C using electron paramagnetic resonance (EPR) with 5,5-dimethylpyrroline-N-oxide (DMPO) as a spin trap and glutathione (GSH) regeneration as an indicator of hexose monophosphate shunt (HMPS) activity. EPR investigations were also done after pre-incubation with N-ethylmaleimide (NEM) to inhibit the GSH system. Furthermore, we determined the RBC redox state in 15 HD patients and 15 controls.

RESULTS

There was no difference between HD patients and controls in the elimination of t-BOOH-generated free radicals in the RBCs. A more than 20-fold increase in radical concentration was observed after GSH trapping with NEM. In this case, we found a delayed decrease of the relative radical concentration in HD patients compared with controls with a significant difference after 7 min (2.2+/-0.26 vs 1.60+/-0.21; P=0.005) and after 10 min (1.82+/-0.41 vs 0.83+/-0.44; P=0.001). GSH regeneration via HMPS did not differ between the RBCs of HD patients (99.5+/-13.5 nmol/min x ml RBC) and those of the controls (94.2+/-16.9 nmol/min x ml RBC). There were no differences in the RBC concentrations of GSH, GSSG, NADP, NADPH, and in the GSH/GSSG and NADP/NADPH ratios between HD patients and controls.

CONCLUSIONS

These data suggest a strong antioxidant potential in the GSH system of erythrocytes without any evidence of a disturbance in HD patients. The HMPS pathway also appears not to be impaired in the RBCs of HD patients. However, the slower radical elimination in the RBCs of HD patients after inhibition of GSH-depending radical scavengers as compared with controls indicates a defect in the antioxidant forces outside the GSH system, and could be one reason for the reduced lifespan of RBCs in HD patients.

[Fluoroquinolones: utilization in renal and urogenital tract infections]

The purpose of this review is to give an introduction in the class of fluoroquinolones, which has become a large class of substances, and to discuss the use, role, and place of these drugs in the treatment of urinary tract infections. The classification of the fluoroquinolones contains four groups. Antibacterial spectrum, pharmacokinetics, and indications are the main criteria. The various fluoroquinolones differ in their antibacterial spectrum, the antibacterial activity, and pharmacokinetic properties. Therefore selection, use, and dosage regime of the substances should be carried out under respective clinical requirements and medical points of view. The physician has to consider the specific indications for each substance in each individual case. Fluoroquinolones are suitable antibacterial agents for various urinary tract infections and are a valuable and useful addition to the antimicrobial treatment.

S-Fimbria-encoding determinant sfa(I) is located on pathogenicity island III(536) of uropathogenic Escherichia coli strain 536

The sfa(I) determinant encoding the S-fimbrial adhesin of uropathogenic Escherichia coli strains was found to be located on a pathogenicity island of uropathogenic E. coli strain 536. This pathogenicity island, designated PAI III(536), is located at 5.6 min of the E. coli chromosome and covers a region of at least 37 kb between the tRNA locus thrW and yagU. As far as it has been determined, PAI III(536) also contains genes which code for components of a putative enterochelin siderophore system of E. coli and Salmonella spp. as well as for colicin V immunity. Several intact or nonfunctional mobility genes of bacteriophages and insertion sequence elements such as transposases and integrases are present on PAI III(536). The presence of known PAI III(536) sequences has been investigated in several wild-type E. coli isolates. The results demonstrate that the determinants of the members of the S-family of fimbrial adhesins may be located on a common pathogenicity island which, in E. coli strain 536, replaces a 40-kb DNA region which represents an E. coli K-12-specific genomic island.

Secretion of cytokines by uroepithelial cells stimulated by Escherichia coli and Citrobacter spp

Urinary tract epithelial cells (T 24/83) are able to express interleukin (IL)-6, IL-8, platelet-derived growth factor (PDGF) and tumour necrosis factor-alpha, but not IL-1 beta, IL-2, IL-4 and IL-10 in response to an infection with uropathogenic bacteria. The process of cytokine secretion is time dependent, with a significant increase in the cytokine activity after 60 min. The expression of virulence factors of the bacteria does not seem to play a role. The interaction between bacterial products (e.g. lipopolysaccharide) and/or bacterial adhesion mediated by adhesins and specific receptor molecules of cell surfaces may be responsible for the activity of mediator protein expression in the epithelial cells. The release of PDGF and IL-8 was found to be higher when due to Escherichia coli HB 101 (rough form) than that caused by other bacterial strains. Citrobacter CB 3009 provoked the highest level of IL-6. The PDGF level correlated significantly with IL-6 and IL-8 values (P<0.001). There was a significant correlation between the time-dependent release of IL-6 and IL-8 (P<0.05). In epithelial cytokine response to bacterial infection, the reaction of the epithelial cells may modify themselves (e.g. internalization of bacteria) and the immuno-regulatory processes that are caused by infection and responsible for parenchymal injury.

High phosphorus intake only slightly affects serum minerals, urinary pyridinium crosslinks and renal function in young women

OBJECTIVE

Assessment of the physiological effects of a diet rich in phosphorus in young women.

DESIGN

Control period I--commercial basic diet containing 1700 mg P and 1500 mg Ca/day for 4 weeks. Supplementation period--a 6 week high-phosphorus period of 3008 mg P and 1995 mg Ca/day. Control period II--4 weeks washout with basic diet as in period I.

SETTING

Institute of Nutritional Science, Friedrich Schiller University, Jena.

SUBJECTS

Ten healthy women, aged 20-30y.

INTERVENTIONS

Orange juice and tablets, containing supplements of Ca5(PO4)3OH and NaH2PO4, totalling 1436 mg elemental phosphorus per day.

RESULTS

There was an increase of 10.7+/-13.7 pg/ml in serum PTH, a decrease of 0.6+/-0.6 ng/ml in serum osteocalcin, an increase of 73.6+/-136.6 nmol/mmol creatinine in urinary pyridinoline and of 19.3+/-36.0 nmol/ mmol creatinine in urinary deoxypyridinoline, and a decrease of 2.6+/-9.3 mg/l in urinary microalbumin. All changes were insignificant. There were no changes in serum levels of Ca, PO4 or Zn, in serum concentration of 1,25-(OH)2D3, and in urinary beta-2-microglobulin excretion. Phosphorus supplementation caused intestinal distress, soft stools or mild diarrhoea.

CONCLUSIONS

In spite of a high phosphorus supplementation no significant changes in bone-related hormones, pyridinium crosslinks as markers of bone resorption and parameters of renal function in young women were found.

Abnormal growth and clonal proliferation of fibroblasts in an animal model of unilateral ureteral obstruction

The time course for the development of renal interstitial fibrosis (RIF) in rats between days 5 and 25 after unilateral ureteral obstruction (UUO) was studied. In kidneys with UUO under histological examination, an interstitial fibrosis was observed after more than 10 days with progression up to day 25. On day 5, collagen peptidase activity in homogenates of UUO kidneys was about 50% higher than in controls but gradually declined afterwards until reaching the level obtained from contralateral kidneys (CL) on day 25. 10 days after UUO, renal hydroxyproline content was elevated about twofold as compared to CL and sham-operated rats, and increased considerably by day 25 of UUO. In primary cultures of cells obtained from UUO kidneys, fibroblast proliferation increased regardless of the extent of fibrosis. This could be a result of an early inflammatory process. Renal fibroblasts from rats are heterogenous when studied in vitro. When fibroblasts of passage 1 obtained from kidneys 25 days after UUO were plated at low density, the number of mitotic type I clones was elevated 5.5-fold as compared with cultures from CL kidneys. The majority of type I clones in UUO cultures from fibrotic kidneys developed in an unusual fashion with formation of three-dimensional structures. The changes detectable under the unfavorable conditions of clonal culture suggest phenotypical differentiation of a small fraction of fibroblasts from kidneys with RIF. These cells are able to overgrow cell monolayers forming circular growing colonies. Obviously, one needs to distinguish between intensive proliferation as a consequence of acute inflammation, and the changes in phenotype of a small fraction of renal fibroblasts which are resistant to normal physiologic regulative mechanisms in cell culture. The latter may contribute to matrix disorders and RIF.

[Asymptomatic bacteriuria]

With the availability of methods to quantitate microbes in urine, one has come to recognize that a certain proportion of apparently healthy individuals have bacteria in their urine in the absence of any clinical symptoms. By definition, asymptomatic bacteriuria is present, if on 1, 2 or more consecutive occasions > 100,000 colony forming units/ml are found in aseptically collected midstream urine, granted that the same microorganism is isolated. Such asymptomatic bacteriuria is found in 2.7% of women aged between 15 and 24 years and increases to 20 to 50% in women above an age of 80 years. In men the prevalence of asymptomatic bacteriuria is considerably lower, but increases to 6 to 20% above the age of 80 years. The microbe most frequently involved in asymptomatic bacteriuria is Escherichia coli, which is characterized by the expression of multiple virulence factors. In this respect they differ from bacteria found in patients with lower or upper urinary tract infections. There is a consensus that in the absence of anatomical or functional abnormalities of the urinary tract asymptomatic bacteriuria per se does not lead to renal scarring, renal dysfunction, or hypertension. The overall prevalence of asymptomatic bacteriuria in pregnancy varies between 2 and 10% with the very small risk of an acute symptomatic episode of urinary tract infection in early pregnancy, but with a substantial risk (30 to 60%) during the last trimester. There is an association between asymptomatic bacteriuria and low birth weight. Asymptomatic bacteriurias are seen in 4 to 60% of immunosuppressed renal graft recipients. The incidence of asymptomatic bacteriuria is also high among patients with diabetes mellitus; the prevalence is approximately 3 fold higher in adult women (7.9 to 11.1%). In these patients asymptomatic bacteriuria does not carry a renal risk. Renal functional prognosis in uncomplicated asymptomatic bacteriuria is excellent. Therefore asymptomatic bacteriuria should be treated during pregnancy, after renal transplantation, prior to urological interventions and in patients with frequent episodes of symptomatic urinary tract infection.

[Erythrocytes in the urine: glomerulonephritis or other source of bleeding. Answer with the microscope]

On the basis of an evaluation of the morphology of erythrocytes in urinary sediment, it is possible to distinguish between nephrological and urological hematuria. In the case of the former, the cells have "disruptive characteristics" (membrane evagination, ring formations, dwarf forms and loss of hemoglobin), enabling them to be distinguished from the regularly formed erythrocytes from hemorrhage within the urinary tract. Dysmorphic erythrocytes retain their characteristic shapes even when persisting in the urine for lengthy periods. An assessment of erythrocyte morphology forms a suitable basis for choosing appropriate further diagnostic measures for urological or nephrological work-up. The method of examination is simple and readily reproducible, and should therefore form an early part of the diagnostic strategy. Microscopic assessment erythrocyte shape is not suitable for the diagnostic work-up of tumors, nor can it obviate the need for kidney biopsy for the investigation of histomorphological changes in glomerular nephritis.

Time course of cytokine mRNA expression in kidneys of rats with unilateral ureteral obstruction

The development of renal interstitial fibrosis (RIF) is related to the expression and excretion of cytokines and growth factors. Thus, we investigated the time course of mRNA expression of cytokines known as causative factors in a model of RIF in rats before and on day 10 after unilateral ureteral obstruction (UUO), when first signs of fibrosis were visible, as well as during progressive RIF. UUO causes a fivefold increase in mRNA expression of monocyte chemoattractant protein 1 15 days after surgery as compared with contralateral kidneys. The level remains elevated about three-fold up to day 25. The mRNA of the fibrogenic cytokine transforming growth factor beta 1 (TGF-beta1) is increased two- to threefold during the time course, whereas the mRNAs of platelet-derived growth factor B chain (PDGF-B) and its receptor beta (PDGF-Rbeta) increase after UUO, reaching their maxima on days 10-15. PDGF-B mRNA increase up to day 15, marking the onset of fibrosis, and decreases thereafter, whereas the expression of the PDGF-Rbeta mRNA remains elevated more than threefold over the entire study period. Incubation of cultured renal fibroblasts with TGF-beta1 and/or PDGF-B suggests that their specific action on cell growth and proliferation is maintained even when they are used in combination. The sustained elevation of TGF-beta1 and PDGF-B/PDGF-Rbeta mRNA levels confirms the assumption of a particular involvement of these cytokines in the pathogenesis of RIF. The mRNA expression of the gap junctional protein connexin 43 in ureteral ligated kidneys is increased sixfold already 5 days after UUO. In this way, the increased connexin 43 mRNA levels indicate a possible function in the remodeling of the kidney tissue after tubular damage and fibrosis.

The "point of no return" and the rate of progression in the natural history of IgA nephritis

BACKGROUND

Based on the observation of 7 patients with chronic IgA nephritis and on a course to end-stage renal failure after several years, D'Amico et al. [1993] reported on a "point of no return" at 2.5 to 3 mg/dl serum creatinine. After exceeding this limit all 7 patients exhibited an irreversible progressive renal failure.

PATIENTS AND METHODS

Therefore, 115 patients with IgA nephritis from the "German Glomerulonephritis Therapy Study" were examined in order to look for the existence of such a "point of no return".

RESULTS

Three different courses could be distinguished: a stable chronic course with constantly normal or only minor elevated serum creatinine lasting for years (91 patients), a progressive course with continuously increasing serum creatinine (22 patients), and a rare (only 2 patients) early acute course with a short-term increase of serum creatinine followed by a rapid return to the normal range. After exceeding 3 mg/dl serum creatinine no remissions were observed in the progressive cases. Sixteen patients showed a rapid, continuously progressive course until end-stage renal failure with exactly the same progression as the 7 patients of D'Amico et al. Six patients of the 22 progressors were not observed long enough. The serum creatinine level doubled on average from 3 to 6 mg/dl within 10 months.

CONCLUSION

Our study confirmed the existence of a "point of no return" at 3 mg/dl (265 micromol/l) during the natural course of chronic IgA nephritis.

The influence of ofloxacin (Tarivid) on the parasite-host inter-relationship in patients with chronic urinary tract infection

In urinary tract infection (UTI), the aim of antimicrobial chemotherapy is either to attenuate the virulence of infective micro-organisms, to influence the interaction between germs and host or to kill bacteria. In 25 females (aged 49.8+/-14.7 years) with chronic UTI, parameters of inflammation (CRP, alpha 2-globulin, leukocytes, ESR) as well as renal function were analyzed under the treatment with ofloxacin 2 x 200 mg. Subsequently, bacterial attachment, bacterial count, leukocytes, antibody-coated bacteria (ACB), immunoglobulin (Ig) G, albumin, a2-microglobulin, Tamm Horsfall protein, secretory IgA (sIgA) and lysozyme were determined in urine. The micro-organisms were examined with regard to the expression of hemolysin, aerobactin, P-fimbriae and according to their plasmid profile. Ofloxacin serum levels were analyzed once prior to, on day 6 during and on day 3 after drug administration. In all cases, the acute clinical symptoms had disappeared after 10 days of treatment, all bacteria were eliminated, and the parameters of inflammation in serum and urine had returned to normal. On the sixth day of therapy, no expression of P-fimbriae was detectable in the Escherichia coli strains isolated, and the attachment rate decreased from 42+/-30.9% to 11.1+/-18.1%. The sIgA level rose from 42.6+68.5 prior to therapy to 88.8+/-136.8 mmol/l on day 3 after therapy; acute symptoms of UTI did not recur in any case during the period of 1 year.

Colocalization of BAX and BCL-2 in small intestine and kidney biopsies with different degrees of DNA fragmentation

Morphological changes associated with apoptosis are closely correlated with the expression of specific proteins. However, the cause-effect relationships between the expression of these proteins and DNA degradation are barely known. For studying expression of apoptosis-related proteins in relation to different degrees of DNA fragmentation, the small intestine with its spatially organized continuum of proliferation, differentiation and death is a very useful preparation. Enterocytes towards the apex of the villi become increasingly susceptible to apoptosis. Here, this "apoptotic gradient" is used to demonstrate the presence of BAX and BCL-2 proteins in the cytoplasm of cells at the onset of apoptosis. In semithin serial sections of the small intestine, BAX, BCL-2 and DNA fragmentation were demonstrated. BAX and BCL-2 are always colocalized and only in cells with fragmented DNA. The gradient of BAX or BCL-2 staining is similar to the gradient of DNA fragmentation. Immunoreactivity for BCL-2 or BAX is most intense in cells that are prone to become apoptotic next in the course of cellular turnover but not in cells in an advanced apoptotic state, showing strongly condensed chromatin. When using the same technique on semithin sections of kidney biopsies, containing epithelia with low cellular turnover, we found DNA fragmentation mainly in the epithelial cells of the distal tubules. Similar to the situation in the enterocytes, BAX staining was confined to the cytoplasm of epithelial cells with a moderate degree of DNA fragmentation and reduced in epithelial cells with a high degree of DNA fragmentation. In contrast to the situation in the small intestine, very low levels of BCL-2 were found. The results suggest that expression of BCL-2 and BAX is related to cell damage as indicated by DNA fragmentation but not to advanced stages of cellular death, as indicated by chromatin condensation and cellular shrinkage.

Cell cultures from cryopreserved renal biopsies and other tissue samples

Answering questions regarding research or clinical aspects, histological and histochemical examinations of tissue specimens are playing an increasing role. The same is true for cell cultures obtained from organ specimens. In most cases, tissue samples are obtained only once and have to be examined immediately. This is often impracticable and therefore, it is necessary to store tissue samples or cells from established cell cultures so as to be able to continue examinations at a later time. Very rare reports exist on the preservation of tissue for performing cell culture examinations and they exclusively refer to tumour tissue and bone marrow, but not to normal organ tissue and biopsy samples. Therefore, in this study cell cultures from several organs have been prepared immediately after obtaining the tissue and compared with those established after cryopreservation several months later. The tissue specimens were obtained from rats (kidney, skin, heart) and from humans (kidney, placenta) or were biopsy specimens from the kidney and skin. From all these cryopreparations, typical cells were cultured. There was no significant difference in the mean population doubling time (MPD) and regarding morphological cell criteria between cell cultures obtained from fresh tissue samples after biopsy and those prepared several months after cryopreservation. There was nearly the same ratio between most cell types present in the tissue. From these results we can conclude that in the examined organs cells from cryopreserved tissue can be cultured even months or more than one year later. At least, these results make it possible to answer new questions and repeat different experiments at any time.

31P-magnetic resonance spectroscopy (31P-MRS) of human allografts after renal transplantation

BACKGROUND

31P-Magnetic resonance spectroscopy (31P-MRS) can be used as a non-invasive tool for measuring the relative intracellular concentrations of several phosphorus metabolites in different organs. Various pathological conditions are characterized by different metabolic patterns. We studied the value of 31P-MRS after renal transplantation with both an uneventful and a clinically complicated course.

METHODS

We determined the relative concentrations of phosphate-containing metabolites in renal allografts of humans with 31P-MRS (1.5 Tesla) in the first few weeks after transplantation; 18 patients with an uneventful clinical course and 10 patients who required dialysis after transplantation were examined. Six patients with a stable allograft function 2-3 months after transplantation served as controls.

RESULTS

In patients with primary allograft function, we found a significant correlation between the phosphomonoester/phosphodiester-ratio (PME/PDE) (r = 0.66, r < 0.01) and the time after transplantation, but no correlation between the nucleoside triphosphate (beta-NTP)-concentration (r = -0.11) and the time course. In the patients with primary or early allograft dysfunction caused by histologically proven rejection (n=5), we found a low beta-NTP compared to patients with an uncomplicated clinical course (0.09+/-0.01 vs 0.15+/-0.03), but no differences in the PME/PDE ratio (0.73+/-0.21 vs 0.80+/-0.21). In contrast, the PME/PDE ratio was lowered in three patients with delayed graft function caused by acute tubular necrosis (0.45+/-0.07 vs 0.80+/-0.21), but the beta-NTP concentration was not reduced (0.15+/-0.003 vs 0.15+/-0.03). The 31P-MR spectrum of two patients with cyclosporin A damage was not altered compared to the controls.

CONCLUSIONS

31P-MRS can be used in patients in the early period after renal transplantation. A significant correlation between the PME/PDE ratio and the time course but no change in the beta-NTP concentration was found in patients with primary allograft function in the first 4 weeks after renal transplantation. Different patterns of 31P-MR spectra were observed depending on the different causes of primary and early transplant dysfunction.

[Pathogenetic aspects of urinary tract infection]

Most urinary tract infections are caused by Enterobacteriaceae; E. coli-strains dominating in 50 to 80% of primary infections. Microorganisms possessing the ability to colonize the uroepithelium (fimbriae/pili) and to cytotoxically damage of cells (hemolysin) may initiate acute infections. On the other hand, properties favouring the survival of these strains in the tissue (K-antigen, iron sequestering/aerobactin) tend to produce relapse and/or chronic infection. A variety of host-specific factors, especially glycosphingolipids, on the surface of epithelial cells determine the virulence of pathogenic microorganisms in the urinary tract and the course of a disease. Structural damages resulting from intra- or extrarenal obstructions, disturbances of the urinary flow and metabolic disorders are essential, predisposing factors of a host organism. These different factors and interactions of these mechanisms determine the manifestation and course of urinary tract infections.

[Prevention of reinfection by L-methionine in patients with recurrent urinary tract infection]

PROBLEM

A great variety of different antimicrobial chemotherapeutics is available for the treatment of urinary tract infections. Influencing the course of chronic diseases is a problem because recurrent diseases may result in disturbances of renal and bladder functions as well as in irreversible damages of the renal parenchyma. The present investigations are expected to clarify whether an effective prevention of reinfection in patients with chronically recurrent urinary tract infection is possible by a regular administration of L-methionine (Acimethin).

PATIENTS AND METHODS

33 female patients were included in the examinations. Following acute disease, 23 females (aged: 47.4 +/- 13.3 years) were treated with 3 x 1 tablet of Acimethin (L-methionine) daily over a period of 26 months. Ten female patients (aged: 47.4 +/- 12.2 years) taking 1 tablet of Nevigramon (nalidixic acid) three times daily over 21.6 months served as a control group. Before starting treatment and in the middle of the therapy period control examinations were performed and following the last drug administration so as to assess the therapeutic result.

RESULTS

No acute infection occurred during L-methionine treatment. All parameters of inflammation (leucocyte count, C-reactive protein, blood sedimentation rate, alpha 2-globulin concentration) were in the normal range; no impairment of renal function was observed. Although L-methionine, i.e. nalidixic acid, did not yield any significant changes in the range of bacteria, the adherence of uropathogenic microorganisms to the cells of the urinary tract was reduced. Before L-methionine treatment, the average load of the uroepithelial cells was 95.9 +/- 73.6 bacteria per cell. When the observation period was completed, 51.2 +/- 56.4 bacteria per cell were registered (p < 0.03). During nalidixic acid treatment, the rate of adherence was reduced from 74.0 +/- 88.4 to 34.4 +/- 37.8 bacteria per cell (p < 0.25). During L-methionine treatment, no Escherichia coli strains that are able to produce hemolysin or to form aerobactine were found. Among agents adhering to uroepithelial cells, however, an increase in their ability to produce mannose-resistant hemagglutination was conspicuous.

CONCLUSION

L-methionine is suitable to prevent reinfection with chronic urinary tract infection. The therapeutic result is essentially due to its influence on bacterial cytoadherence. In contrast to the established recommendations concerning the prevention of reinfection by the use of antibiotics and sulphonamides selecting resistant strains during long-term treatment, nothing is known about the development of resistance to L-methionine.

[Pathogenesis of interstitial kidney fibrosis. Studies in the rat model of unilateral ureteral obstruction]

BACKGROUND

The animal model of unilateral ureteral obstruction (UUO) of the rat is suitable to cause a renal interstitial fibrosis within a few weeks. Prior to the 10th day after UUO, no fibrotic changes were detectable in ureter-ligated kidneys, whereas after day 20 fibrosis was developing strongly.

METHOD

Using cell cultures it was examined whether any in vivo changes in proliferation and function of fibroblasts are also detectable in cell cultures and whether, due to their persistency, they are of fundamental importance for the development of renal interstitial fibrosis.

RESULTS

The comparison of the proliferation in cell cultures established 5 and 21 days after UUO showed that the cultures of the two experimental groups behave similarly. Consequently, the action of acute inflammatory processes on fibroblast proliferation without any existing fibrosis is comparable with that of pronounced fibrosis in the animal model. High concentrations of fetal calf serum in the culture medium cause a stimulation of the cell proliferation as well as a selection of mitotically active differentiation stages of fibroblasts.

CONCLUSION

Obviously, the loss of inhibition of the fibroblast proliferation under the conditions of cell culture causes similar changes to those effected by pathogenic mechanisms in the kidneys of rats with UUO. If the behaviour of fibroblasts in organs is to be assessed using results of cell culture experiments, the stimulating action of the culture conditions and the missing influence of other cells present in the tissue should be considered. These factors make the recognition of remaining differences between cells from normal and damaged kidneys more difficult under the conditions of primary cell cultures.