[Morphologic and functional assessment of renal artery stenosis: use of combined MR angiography and MR renography--preliminary report]

PURPOSE

To assess the possibility of use of multiphase magnetic resonance angiography for simultaneous acquiring of angiographic images and curves of contrast enhancement of renal cortex, medulla and pyelocalyceal system and evaluation of quality of obtained images.

MATERIAL AND METHODS

Twenty-four patients suspected of having renal artery stenosis underwent power-injection of 30 ml of Gd-DTPA (3 ml/sec). From 10 to 360 seconds after the beginning of the injection, 3D MRA sequence was performed multiple times. Acquisition time of single phase of MR examination was 7.5-8 sec (TR = 5 ms, TE = 1:6 ms, single 7 cm thick slab with 35 partitions, 164 x 512 matrix). First three phases were used to obtain angiographic images. All phases were used to obtain curves of renal cortical, medullary and pyelocaliceal enhancement. Two readers evaluated quality of MRA images, as well as, quality of enhancement curves.

RESULTS

21 of 24 MRA examinations were of good, 2 of fair and none of poor quality. Quality of enhancement curves was good in 22 cases. It was suboptimal in 2 cases because of irregular breath-holding. Maximum number of acquisitions per minute was 4-5. Eight accessory, 2 obstructed and 9 stenosed renal arteries were visualized. Renographic curves were abnormal in 8 patients.

CONCLUSIONS

MRA sequence with short acquisition time enables simultaneous acquisition of angiographic images and renographic curves of good quality. With further reduction in acquisition time it may be possible to obtain more points on MR renographic curves.

Treatment of chronic hepatitis B and C with interferon-alpha in renal allograft recipients: preliminary results

We evaluated the effects of treatment with interferon (IFN) on liver disease and renal allograft function in ten immunosuppressed cadaver kidney recipients. Two females and eight males (mean age 39 years) with biopsy-proven chronic active hepatitis (n = 8) or persistent hepatitis (n = 2) and serum positive for hepatitis B surface antigen (HBsAg) and HBe antigen (n = 5) or serum positive for anti-HCV antibodies (n = 3) or serum positive for HBsAg, anti-HCV and anti-HDV antibodies (n = 2) received 3 million units IFN thrice weekly of 6 months. All patients responded with a reduction in serum aminotransferase activity and in five of them liver function completely normalized. Three patients among five infected with HBV cleared HBeAg. During the follow-up period liver function remained stable in 9 patients after discontinuation of IFN therapy. Three patients lost their grafts due to rejection 1, 2, and 4 months after IFN therapy, respectively. In six patients renal function remained stable during and after IFN therapy. We conclude that in selected groups of renal allograft recipients IFN can be used safely and effectively for the treatment of chronic viral hepatitis.

Fucoidan improves the renal blood flow in the early stage of renal ischemia/reperfusion injury in the rat

It has been shown that monoclonal anti-P-selectin antibody administration protects renal function in an ischemic model of acute renal failure. This study was designed to evaluate the effect of administration of fucoidan, P-selectin inhibitor, on reduction in renal blood flow induced by ischemia/reperfusion injury in the rat. Experiments were performed on male Wistar rats weighting 35-400 g. The systemic blood pressure (mm Hg) (BP) and renal blood flow (RBF) were monitored continuously and renal vascular resistance (RVR) was calculated. After 20 min period of stabilization animals (6 rats in each group) received one of the following agents administered by continuous i.v. infusion during 165 min: 1 mg/kg of body weight of fucoidan (F1), 10 mg/kg of fucoidan (F10), 100 mg/kg of fucoidan (F100), 10 mg/kg of heparin (H), or 0.9% NaCl solution (control). After 15 min of drug administration the renal vessels of the both kidney were occluded with vascular clamps for 60 min. There were no significant changes in the initial values of RBF, RVR and BP between groups. None procedure affected significantly BP during all experiments. In F10 RBF returned to the initial values in 70th min of reperfusion and did not change up to 90th min. This value was significantly higher than respective value in the control group. In F1 group RBF in 90th min was also higher than in the control group, but it was not statistically significant. The dose of heparine and fucoidan used in the H and F100 groups failed to preserve RBF during reperfusion. In the present study we found that administration of fucoidan--P-selectin inhibitor, increases significantly postischemic renal blood flow and may have renoprotective activity.

Fucoidan inhibits smooth muscle cell proliferation and reduces mitogen-activated protein kinase activity

OBJECTIVES AND DESIGN

fucoidan has previously been shown to inhibit the proliferation of arterial smooth muscle cells both in animal models and in vitro. However, the mechanisms behind the anti-proliferative effects of this polysulfated polysaccharide are not known in detail. Here, the inhibitory effect of fucoidan on rat aortic smooth muscle cell proliferation was examined and compared with the effects of heparin after stimulation with fetal calf serum, platelet-derived growth factor BB, basic fibroblast growth factor, heparin-binding epidermal growth factor, and angiotensin II.

MATERIALS AND METHODS

the cultures were analysed with respect to cell proliferation and DNA synthesis by cell counting and measurement of(3)H-thymidine incorporation. Phosphorylation of mitogen-activated protein kinase and nuclear translocation of phosphorylated mitogen-activated protein kinase were studied by immunoblotting and immunocytochemistry.

RESULTS

fucoidan was shown to be a more potent inhibitor of smooth muscle cell proliferation than heparin. Fucoidan also reduced growth factor-induced activation of mitogen-activated protein kinase and prevented nuclear translocation of phosphorylated mitogen-activated protein kinase.

CONCLUSION

fucoidan is a more potent anti-proliferative polysulphated polysaccharide than heparin and may mediate its effects through inhibition of the mitogen-activated protein kinase pathway in a similar manner as heparin.

DNA from rejecting allografts can be detected in recipient nonlymphoid tissues

The main source of donor DNA in recipients of allograft are "passenger" cells. They are claimed to be responsible for the posttransplantation microchimerism and prolongation of allograft survival. We have noticed that beside of the cellular microchimerism, donor DNA can be found in the recipient tissues at the time of rejection of allograft. In this study we provide evidence for presence in the recipient of both, DNA in "passenger cells" and free DNA in tissues at terminal stage of rejection. Male BN (RTIn) rat heart or skin were transplanted to female LEW (RTII) rats followed by a vascularized bone marrow in hind-limb transplant. CsA was given in a dose of 17mg/kg b.w. for 30 days, then rats were followed until day 100 unless rejection occurred earlier. LEW blood, spleen, mesenteric node and bone marrow cells were stained with moAb OX27 specific for BN but not LEW. Genomic male DNA was isolated and amplified with SRY oligonucleotide. At day 30 and 100 cellular microchimerism was detected in blood, spleen, nodes and bone marrow cells. Donor DNA was detected in recipient skin, liver and heart extracts, beside of lymphoid organs, at the time of rejection of allograft but not when rats were maintained on CsA. Taken together, donor DNA can be detected in recipient tissues at the time of heart or skin rejection. It seems to be released from cells of rejecting grafts and not from "passenger" cells representing only a minor cellular mass compared with the graft.

Factors affecting reactivation of Epstein-Barr virus infection after kidney allograft transplantation

OBJECTIVES

Reactivation of Epstein-Barr virus (EBV) infection in renal transplant recipients may cause significant morbidity and mortality. To evaluate factors associated with activation of EBV replication we followed prospectively a group of 65 recipients of cadaveric kidney for 12 months.

METHODS

Sera were collected periodically from these patients and analyzed for the presence of specific anti-EBV antibodies. Control group consisted of renal (n=35) and healthy blood donors (n=35). Enzyme-linked immunoassays based on recombinant EBV proteins were used to detect the following antibody specificities: early antigen (EA) IgA, IgM, and IgG, nuclear antigen (EBNA) IgG.

RESULTS

During first year after transplantation, primary infection developed in 4 (6.15%) recipients and reactivation occurred in 18 (27.7%) recipients. Analysis did not show the association of reactivation with type of basic immunosuppressive therapy, prophylactic or therapeutic use of anti-lymphocyte antibodies, as well as acute rejection episodes. There was a borderline association (p=0.068) between the incidence of CMV infection and EBV reactivation.

CONCLUSIONS

Our data suggest casual relationship between CMV infection and EBV reactivation.

Arteriosclerosis in rat aortic allografts: early changes in endothelial integrity and smooth muscle phenotype

BACKGROUND

Transplant arteriosclerosis remains a limiting factor for the long-term survival of transplanted organs and effective treatment is lacking. A rat model of aortic allografts was used to analyze this process by electron microscopy and further characterize the phenotypic properties of the cells involved.

METHODS

A segment of abdominal aorta was transplanted orthotopically from Fischer to Lewis rats. The animals were killed 1-12 weeks after the operation (four to six rats/group), and the grafts were removed and processed for microscopy.

RESULTS

The first changes (1 week) included detachment of endothelial cells, adhesion of degranulating platelets to the subendothelial matrix, and modification of smooth muscle cells in the media. The latter process was distinguished by loss of myofilaments and formation of a prominent endoplasmic reticulum and Golgi complex (shift from contractile to synthetic phenotype). Subsequently, modified smooth muscle cells invaded the intima. In parallel, lymphocytes and monocytes/macrophages infiltrated the intima and adventitia. The neointima grew in size by cell proliferation and production of extracellular matrix (4-8 weeks). Smooth muscle cells and monocytes/macrophages in the neointima and media were also noted to accumulate cytoplasmic lipid droplets and eventually turn into foam cells and die. Within the lipid-rich cell remnants, calcification occurred. Finally (12 weeks), the growth in mass of the intimal lesions ceased and in some places reformation of an endothelial lining was detected. Few viable smooth muscle cells remained in the media and the inflammatory infiltrate in the adventitia was reduced.

CONCLUSIONS

These observations highlight the importance of early changes in endothelial integrity and smooth muscle phenotype in the development of allograft vascular disease and form the basis for a partly modified model of the cellular mechanisms in this process.

The effect of cyclosporine on regulators of fibrinolysis in plasma from renal allograft recipients

Fibrinolytic disturbances are thought to play an important role in processes leading to deterioration of renal allograft function. We investigated the effect of CsA therapy on the regulation of fibrinolysis in kidney graft recipients by measuring plasma concentration and activity of plasminogen activators (tPA, uPA) and their inhibitors (PAI-1, 2). We found an increase in tPA activity and in PAI-1 concentration as well as a decrease in PAI-1 activity in renal allograft recipients as compared to healthy controls, but did not confirm a correlation between these observations and CsA administration. tPA and PAI-2 concentrations as well as uPA activity did not significantly differ between the studied groups. We showed a significant decrease in uPA plasma concentration in patients treated with azathioprine. The significance of this finding is unknown.

Clinical course of concomitant Hbv and Hcv infection in renal allograft recipients

We evaluated the impact of concomitant infection with Hepatitis B virus (HBV) and Hepatitis C virus (HCV) on the clinical course after renal transplantation (Tx). In 335 patients (pts) transplanted between 1991 and 1993 we found 30 (9%) recipients who were positive for Hepatitis B surface antigen (HBsAg) (ELISA, Organon) and anti-HCV antibodies (immunoblot assay Lia Tek) preTx. Chronic liver disease (CLD) (two-fold or greater increase in serum ALT and AST levels for at least six months) developed in 40.7% coinfected pts as compared to 24.4% and 25.7% pts infected only with HCV or HBV, respectively. Maintenance immunosuppression consisted of P + Aza + CsA, mean follow-up time was 28 +/- 15 months. The mean time of the onset of CLD was 3.0 months (range: 1-18 months) after Tx. Percutaneous liver biopsy performed in 5 CLD pts revealed chronic active hepatitis (CAH) in 4 and chronic persistent hepatitis (CPH) in 1 pt. Four pts who had CAH and were positive for HCV RNA (RT PCR) in serum and for HBcAg in liver tissue, received interferon-alpha therapy for 6 months. Clinical improvement of liver function was observed in all of them, but none cleared HBsAg or HCV RNA. One pt lost his graft due to acute rejection. Concomitant infection with HBV and HCV is associated with the high risk of development of CLD early after Tx. We recommend that pretransplant evaluation of both anti-HCV and HBsAg positive pts should include liver biopsy to exclude potential recipients with CAH.

Higher exposure to cyclosporine A with unchanged tolerability in patients converted from Sandimmun to Sandimmun Neoral

Neoral (NEO) is claimed to have better pharmacokinetics than standard preparation of cyclosporine (SIM) thus providing more reliable immunosuppression. We estimated safety and tolerability of NEO and compared pharmacokinetic parameters in 20 stable renal allograft recipients (RARs) converted from SIM to NEO treatment. Another 20 stable RARs continuously treated with SIM created a control group. Whole blood through CsA level (C0) did not differ after conversion (SIM: 136.2 +/- 33 ng/ml and NEO: 142.6 +/- 34 ng/ml). During therapy with NEO peak blood concentration (Cmax) was significantly higher (935.6 +/- 368 ng/ml) and occurred earlier (Tmax 1 hr. 36 min. +/- 30 min) as compared to the period on SIM (Cmax 598 +/- 309 ng/ml, p = 0.01), Tmax = 3 hr. +/- 1 h 36 min., (p = 0.01) respectively. AUC increased from 2975.4 +/- 1020 ngxhr/ml to 4236.1 +/- 1188 ngxhr/ml (p < 0.0001). Correlation coefficient between AUC and C0 was higher during NEO (r = 0.52) than SIM therapy (r = 0.32). The only noticeable change in laboratory tests after switch to NEO was slight increase of serum triglyceride concentration (119.5 +/- 44.7 mg/dL vs. 148.4 +/- 67.0 mg/dl). The mean serum creatinine concentration did not change significantly (1.42 +/- 0.32 mg/dL and 1.46 +/- 0.31 mg/dL). Tolerance of NEO was good and 1:1 switch from SIM to NEO is clinically safe. Higher bioavailability of NEO was not associated with decreased tolerability or increased nephrotoxicity. Better correlation between C0 and AUC during NEO administration makes CsA treatment monitoring more reliable.

Intraglomerular fibronectin and laminin turn-over in chronically rejected kidney allografts in humans

Chronic rejection is primarily responsible for the late loss of allografted organs and remains an important clinical problem. Chronic rejection in the kidney is characterised by arteriolosclerosis and nephrosclerosis, glomerulonephritis and interstitial fibrosis. Recently, a large number of studies have indicated that proteolytic enzymes play important roles as mediators of glomerular injury. The aim of the study was to assess intraglomerular fibronectin and laminin contents as well as cysteine proteinases in activity chronically rejected human kidneys. We investigated kidney tissue from graftectomy specimens obtained from 11 patients with end-stage renal disease following chronic rejection. A group of 9 patients undergoing nephrectomy because of cancer served as a control group, but only not involved parts of the kidneys were used. When intraglomerular laminin contents were related to DNA content, significant accumulation in chronically rejected allografts was found in comparison to controls (382 +/- 171 micrograms per microgram DNA and 190 +/- 82 micrograms per microgram DNA, respectively, p < 0.01. The accumulation of fibronectin was higher than in controls, however the difference was not significant. When proteinase activity was related to intraglomerular DNA content, significantly enhanced cathepsin B and L activity was found in rejected kidney allografts (57 +/- 16 nmol AMC/min per mg DNA) in comparison to controls (15 +/- 2 nmol AMC/min per mg DNA). Summarizing, we observed accumulation of fibronectin and laminin in glomeruli and simultaneously an excess of proteolytic activity in human chronically rejected kidneys. The above phenomenon indicates that a very active metabolic process takes place in glomeruli during rejection.

Erythropoietin production after kidney transplantation

We studied production of erythropoietin (EPO) in long-term renal allograft recipients with posttransplant erythrocytosis (PTE). Among 951 recipients we found 74 patients with persistent elevation of hematocrit (Htc) value (female > 50%, male > 55%). However, only 63.5% of them had increased red-cell mass ( = "true" erythrocytosis). In all recipients with PTE known causes of secondary erythrocytosis were not found. EPO titer in peripheral blood was significantly higher in recipients with PTE (median 13.5 mIU/mL, range: 0.1-71.5 mIU/mL) as compared to healthy blood donors (median 5.75 mIU/mL, range: 0.1-19.5 mIU/mL) but not different from the group of renal allograft recipients without PTE (median 13.0, range 0.1-71.7 mIU/mL). However, EPO level measured in pretransplant sera was significantly higher in patients who developed PTE (median 16.4 mIU/mL, range: 1.0-281.2 mIU/mL) than in recipients without PTE (median 8.3, range: 1.0-50.3 mIU/mL). A significant difference in EPO level between systemic and effluent blood from native kidneys was found in 6 out of 14 recipients with PTE who underwent catheterization. After phlebotomy patients with PTE responded with higher increase in peak EPO titer than healthy blood donors (527 +/- 473% versus 194.5 +/- 44.2%, p < 0.05). Our results suggest that PTE develops spontaneously due to increased EPO production. Despite elevated EPO levels, regulation of EPO release remains preserved.

Long-term results of treatment of chronic hepatitis B, C and D with interferon-alpha in renal allograft recipients

The aim of this study was to evaluate the efficacy and safety of interferon-alpha (IFN-alpha) therapy of chronic hepatitis B, C and D (HBV, HCV and HDV, respectively) in renal transplant recipients. A group of 42 patients (30 males, 12 females, mean age 38 years) with documented viraemia and chronic active hepatitis (CAH) were studied, of whom 1 had HBV infection alone, 11 had HCV infection alone, 3 had HBV and HDV infection concomitantly, 12 had HBV and HCV infection concomitantly, and 2 had HBV, HCV and HDV infection concomitantly. Patients received 3 MU IFN-alpha three times weekly for 6 months. After IFN-alpha therapy, 18 patients (43%) achieved normal alanine aminotransferase (ALT) activity and a partial response was observed in 12 (29%) patients. Two patients relapsed (one with HCV and one with HBV + HCV infection) immediately after the cessation of IFN-alpha therapy. Repeated liver biopsy was performed in 16 patients after 6-24 months of therapy and revealed progression to cirrhosis in five patients, remission in two and stable disease in nine. None of the patients cleared HCV RNA, four patients cleared HBeAg (two also HDV), and one both HBV and HCV. Five patients died during IFN-alpha therapy (one as a consequence of liver failure), and four died during the 6 months after therapy (two as a consequence of liver failure). During IFN-alpha therapy renal allograft function remained stable in 31 patients and acute rejection episodes occurred in 7, of whom 5 lost their graft and all had experienced rejection episodes before. In 16 patients normalization of ALT continued during long-term follow-up (median 22 months, range 0-84 months). IFN-alpha seemed to be moderately effective in the treatment of chronic HBV or HCV infections, but cannot be recommended for recipients infected with both HBV and HCV.

Cyclosporine A blood concentration during pregnancy in renal allograft recipients

Pregnancy-induced changes increase hazards associated with cyclosporine (CsA) treatment. Blood CsA trough levels (C0) were estimated in 15 pregnant renal allograft recipients treated with prednisolone + CsA + azathioprine using the TDx Abbott fluorescent polarization immunoassay. Despite therapeutical dose levels of CsA administered during pregnancy (3.52-3.67 and 3.59 mg/kg body weight in the first, second, and third trimesters, respectively), C0 significantly decreased (first trimester 130.8 +/- 36.9, second 92.0 +/- 32.7, and third 99.0 +/- 36.9 ng/ml). The mean increase of patient's body weight in mid-pregnancy was 3.0 +/- 2.19 kg and was associated with a significant (P < 0.05) fall in a hematocrit value (from 42 +/- 4.9% prior to pregnancy to 34 +/- 6% at the 20th week). We postulate that C0 concentration does not reflect the true exposure to CsA as no episodes of acute graft rejection were observed during pregnancy.