Increased serum beta 2 microglobulin during rejection, cyclosporine-induced nephrotoxicity, and cytomegalovirus infection in renal transplant recipients

In 83 renal transplant recipients, serum beta 2 microglobulin (beta 2m) levels were significantly elevated during pretransplant uremia, rejection, cyclosporine-induced nephrotoxicity, and infections. In patients with normal serum creatinine, 74% had elevated serum beta 2m levels. None of the cyclosporine-treated patients had normal levels of beta 2m. Patients with stable renal allograft function receiving cyclosporine showed significantly higher serum beta 2m (P less than 0.001) and serum creatinine (P less than 0.01) levels than azathioprine treated patients. Patients with an irreversible rejection showed significantly higher serum concentrations of beta 2m than patients experiencing a reversible rejection (P less than 0.001). During cytomegalovirus (CMV) infection the serum beta 2m levels were elevated compared with other infections (P less than 0.001), while the serum creatinine was not. However, infected patients had higher serum levels of beta 2m and creatinine than patients with stable renal allograft function (P less than 0.001). Serum beta 2m may therefore be useful in the early diagnosis of CMV infection. To conclude, serum beta 2m levels cannot distinguish between rejection, cyclosporine nephrotoxicity, or infection.     

Urine macrophage migration inhibitory factor concentrations as a diagnostic tool in human renal allograft rejection.

BACKGROUND: Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that is a potent activator of macrophages and T cells. Previous studies have shown that local MIF production is increased in acute renal allograft rejection, suggesting that it may play an important role in the rejection process. AIMS: To determine if urine and serum MIF concentrations: (1) are increased in acute rejection, and (2) can be used as noninvasive tools to discriminate between acute rejection (AR) and cyclosporine nephrotoxicity (CyA toxicity). METHODS: In a prospective study of nine renal allograft patients (five acute rejection and four stable), serial urine MIF concentrations were measured by ELISA in the first 14 days after transplantation. In a retrospective study, MIF concentrations in urine and serum were measured in 24 patients who were biopsied for acute renal transplant dysfunction (11 AR, 13 CyA toxicity). Urine and serum MIF were also measured in 23 stable renal transplant patients and 10 normals. RESULTS: MIF was readily detected in the urine of normal healthy controls (106+/-61 pg/micromol creatinine). In the prospective study, the urinary MIF concentration was increased substantially on day 1 posttransplantation and subsequently fell in parallel with the serum creatinine. However, urine MIF increased before episodes of biopsy proven acute rejection. The retrospective study showed that urine MIF concentrations in patients with AR were increased 5-fold compared to normal controls (439+/-313 pg/micromol Cr; P<0.01). In contrast, urine MIF concentrations in CyA toxicity were not significantly different to normal controls (145+/-119 pg/micromol Cr; P=NS). A marked increase in MIF immunostaining was seen in biopsies of AR, but not in CyA toxicity. No significant differences were evident in serum MIF levels between normals and any transplant patient group. CONCLUSIONS: These results suggest that measurement of urine MIF concentration may be useful in monitoring renal transplant patients for acute rejection and as a discriminator from cyclosporine nephrotoxicity.     

Renal expression and urinary concentration of EGF and IL-6 in acutely dysfunctioning kidney transplanted patients

Background: Despite marked improvements in the success of solid organ transplantation, a significant percentage of transplanted organs is lost due to recurrent episodes of acute cellular rejection. The mechanisms that govern allograft rejection likely include a complex regulatory network of multiple cytokines and growth factors. Design and Method: This study investigated the kidney gene (in situ hybridization) and protein (immunohistochemistry) expression and the urinary excretion rate of IL-6 and EGF in 29 renal transplant recipients: 16 with acute cellular rejection (AR) and 13 with acute tubular damage/cyclosporine toxicity (ATD). Results: AR patients displayed a 4-fold increase of renal IL-6 expression, which localized chiefly to proximal tubular cells and monocytes/macrophages, whereas EGF signal was extremely weak or even absent. In ATD patients, EGF expression was markedly reduced, while IL-6 specific signal was unchanged. In all the patients examined the renal expression of IL-6 and EGF strictly correlated with their urinary excretion rate (r:0.459, P:0.001). Thus, urinary IL-6/EGF ratio was markedly increased in the former group (>20-fold at day 1), where it parallelled the modifications of plasma creatinine over time (r:0.603, P <0.0001), and was only slightly increased in the latter group (<3-fold). Conclusion: Kidney transplanted patients with acute cellular rejection or acute tubular damage/CyA nephrotoxicity exhibit a distinctly different pattern of intragraft expression of IL-6 and EGF, which is closely reflected by their rate of urinary excretion.     

普罗布考防治大鼠顺铂急性肾损伤的实验研究

目的：复制大鼠顺铂急性肾损伤模型,研究氧化应激与核转录因子Sp1及凋亡的关系;探讨普罗布考对顺铂急性肾损伤的保护作用及作用机制。方法：24只SD雄性大鼠被随机分为生理盐水对照组、顺铂模型组、普罗布考干预组、普罗布考对照组,每组6只;检测尿N-乙酰-β-D-氨基葡萄糖甘酶（NAG）、血清肌酐（Scr）、血尿素氮（BUN）、肾组织匀浆液丙二醛（MDA）和谷胱甘肽过氧化物酶（GSH-Px）,光镜观察肾脏病理改变;采用免疫组化染色检测肾组织Sp1蛋白表达;采用TUNEL染色检测肾小管上皮细胞凋亡。结果：与生理盐水对照组和普罗布考对照组相比,顺铂模型组大鼠血清BUN和Scr,尿NAG酶,肾脏组织匀浆MDA含量显著升高,肾组织匀浆GSH-Px活力显著下降（P〈0.01）;肾脏指数、肾小管损伤分数和肾小管上皮细胞凋亡百分比均明显增加（P〈0.01）;肾组织Sp1蛋白的表达上调。采用普罗布考干预后血清BUN和Scr,尿NAG酶,肾脏组织匀浆MDA含量显著下降（P〈0.05）;肾组织匀浆GSH-Px活力显著升高;肾脏指数、肾小管损伤分数和肾小管上皮细胞凋亡百分比均明显降低（P〈0.01）;肾组织Sp1蛋白的表达下调。结论：氧化应激和核转录因子Sp1在顺铂所致大鼠肾毒性中起一定作用;普罗布考对顺铂所致大鼠肾毒性有保护作用,其机制可能与抗氧化、抑制肾小管上皮细胞凋亡、下调肾组织Sp1蛋白表达有关。     

Eosinophil granule major basic protein in acute renal allograft rejection

Conventional staining techniques to determine the presence of tissue eosinophils underestimate their number and do not usually detect eosinophil degranulation. We have studied the involvement of eosinophils in acute renal allograft rejection by immunofluorescence localization of eosinophil granule major basic protein (MBP) in the kidney and by measurement of MBP in the plasma and urine by radioimmunoassay. Tissue eosinophilia and extracellular deposition of MBP indicative of eosinophil degranulation were observed in 94% and 87%, respectively, of patients with acute rejection as compared with 17% and 17%, respectively, of patients with cyclosporine nephrotoxicity. The urine levels of MBP were significantly elevated in acute rejection but not in cyclosporine nephrotoxicity. Plasma MBP concentrations were within the normal range in both acute rejection and cyclosporine nephrotoxicity. The presence of marked tissue eosinophilia and eosinophil degranulation did not always indicate irreversible rejection. Interleukin-2 and IL-2 receptors were also elevated in the urine during acute rejection. These results support a role for the eosinophil as an effector of tissue damage during rejection and suggest the potential usefulness of urine MBP determinations for the immunologic monitoring of transplanted patients.     

Is 3-hour cyclosporine blood level superior to trough level in early post-renal transplantation period?

PURPOSE: Cyclosporine dose is traditionally based on trough blood levels. Cyclosporine trough blood level correlates poorly with acute rejection and cyclosporine nephrotoxicity after renal transplantation. We determined whether cyclosporine blood level at any other time point is superior to cyclosporine trough blood level as a predictor of acute rejection and cyclosporine nephrotoxicity. MATERIALS AND METHODS: Cyclosporine blood level was measured before (trough), and 1, 2, 3 and 4 hours after the dose in 156 initial renal transplant cases 2 to 4 days after the initiation of cyclosporine micro-emulsion formula administration. The cylosporine micro-emulsion dose was based on cyclosporine trough blood level targeting 250 to 400 microg./l. RESULTS: Regression analysis revealed that only delayed graft function (p = 0.007) and cyclosporine blood level after 3 hours (p = 0.008) predicted acute rejection. Mean cyclosporine trough blood level plus or minus standard error was not significantly different in patients with and without acute rejection (293+/-21 versus 294+/-11 microg./l.). Mean cyclosporine blood level after 3 hours was significantly lower in patients with acute rejection (1,156+/-90 versus 1,421+/-50, p = 0.008). Cases were divided into tertiles at levels after 3 hours (1,100 and 1,500 microg./l.). The group in which the level after 3 hours was less than 1,100 microg./l. had the highest acute rejection rate (22 of 50 patients, 44%) and a cyclosporine nephrotoxicity rate of 13% (7 of 52 patients). The group in which the level after 3 hours was 1,100 to 1,500 microg./l. had the lowest acute rejection rate (5 of 46 patients, 11%) without increased cyclosporine nephrotoxicity (7 of 52 patients, 13%). A level after 3 hours of greater than 1,500 microg./l. was associated with a rejection rate of 15% (7 of 47 patients) but significantly higher cyclosporine nephrotoxicity (16 of 52 patients, 30%). CONCLUSIONS: Cyclosporine blood level after 3 hours in the early post-transplantation period is associated with acute rejection and cyclosporine nephrotoxicity. A cyclosporine blood level range after 3 hours of 1,100 to 1,500 microg./l. is associated with an optimal outcome. Our data suggest that cyclosporine blood level after 3 hours may represent a better method of monitoring cyclosporine micro-emulsion dose than cyclosporine trough blood level. This hypothesis must be further studied in randomized trials.     

Studies of urinary proteins, FDP (fibrinogen degradation products), and NAG (N-acetyl-beta-D-glucosaminidase) in renal transplanted patients

The urinary proteins, FDP (fibrinogen degradation products), and NAG (N-acetyl-beta-D-glucosaminidase) in renal transplanted patients were studied. SDS (sodium dodecyl sulphate) electrophoresis was used for the differentiation of urinary proteins according to their molecular size. In the azathioprine-treated patients with stable renal function, most of the urinary proteins were albumin. However, the low molecular weight (LMW) proteins, which were suggestive of tubular proteins, appeared in the urine of the ciclosporin-treated patients with stable renal function. During the rejection episodes of the ciclosporin-treated patients, the fraction of LMW proteins increased. The elevation of urinary FDP and NAG index (urinary NAG/urinary Cr) were detected in association with rejection episodes. Urinary NAG index increased in proportion to the elevation of serum Cr. However, the elevation of urinary NAG index was found in some ciclosporin-treated patients with normal serum Cr. The elevation of NAG index without the elevation of urinary FDP occurred in ciclosporin nephrotoxicity. The SDS electrophoresis of urinary proteins, urinary FDP, and urinary NAG index can be useful parameters for monitoring ciclosporin nephrotoxicity.     

Diagnosis of tubular injury in renal transplant patients by a urinary assay for a proximal tubular antigen, the adenosine-deaminase-binding protein

Two murine monoclonal antibodies (URO-4 and URO-4a)--which detect different epitopes of a proximal tubular cell glycoprotein antigen, the adenosine-deaminase-binding protein (ABP)--have been formatted into a sandwich enzyme immunoassay for detection of ABP in the urine. Serial urine samples from 34 renal transplant patients during the first six months posttransplant were analyzed to determine the correlation of this test with clinical rejection and cyclosporin (CsA) nephrotoxicity. In 29/29 acute rejection episodes the ABP level was elevated, beginning 1-7 days prior to treatment of rejection. Eighteen patients were treated for rejection with courses of OKT3 or antithymocyte globulin: 0/6 whose ABP level fell to normal during therapy had rerejection; 10/12 whose ABP level remained elevated had rerejection within 7 days of therapy completion. Of 15 patients treated with CsA, 7 had no rejection or drug toxicity; all 7 had normal ABP levels. The remaining 8 had CsA nephrotoxicity, all in association with elevated ABP levels that rapidly fell to normal with decreased CsA dose. An additional 7 patients with creatinine elevations more than 6 months posttransplant were studied: 5 had chronic vascular changes on biopsy, no response to increased immunosuppression, and normal ABP levels; 2 had a cellular infiltrate on biopsy, response to increased immunosuppression, and elevated ABP levels. We conclude that the urinary ABP assay provides information useful in the management of renal transplant patients with acute and chronic rejection and CsA toxicity.     

Cyclosporine-induced acute renal dysfunction in the rat. Evidence of arteriolar vasoconstriction with preservation of tubular function

Dose-related cyclosporine-induced renal dysfunction is the most frequent adverse effect noted with this exciting immunosuppressive drug. To investigate pathogenetic factors involved, we studied renal tubular function and afferent arteriolar morphology during severe experimental cyclosporine-induced reduction in glomerular filtration rate. Pair-fed male rats were given cyclosporine 50 mg/kg or olive oil vehicle alone by gavage for periods of 3-14 days. Glomerular filtration rate declined progressively, reaching a nadir of 0.18 +/- .05 ml/min/100 g vs. .86 +/- .03 ml/min/100 g in controls at 14 days (P less than 0.001). Despite the severe reduction in glomerular filtration rate there was no difference in fractional sodium excretion, fractional lithium excretion, enzymuria, or in vitro renal cortical slice uptake of tetraethylammonium in cyclosporine and vehicle-treated animals. Light microscopy showed vacuolar changes without evidence of tubular necrosis at 7 and 14 days in cyclosporine-treated rats. Progressive decline in the diameter of the afferent arteriole was noted by scanning electron microscopy. By day 14 the lumenal diameter of afferent arterioles from cyclosporine-treated animals was 8.9 +/- 0.4 micron vs. 13.5 +/- 0.4 micron in controls (P less than 0.05). We conclude that afferent arteriolar vasoconstriction rather than direct tubular injury is a major pathogenetic factor in experimental cyclosporine nephrotoxicity.     

Serum levels of alpha-1 microglobulin in recipients of renal allografts

Serum levels of alpha 1 microglobulin (s-alpha 1 m) in 92 recipients of renal transplants were elevated during pretransplant uremia (P less than 0.001), acute rejection (P less than 0.01), and cyclosporin-induced nephrotoxicity (P less than 0.01). In patients with stable renal function, those treated with cyclosporin had higher s-alpha 1 m than those receiving azathioprine: 81 +/- 4 and 64 +/- 3 mg/l (mean +/- SEM), respectively (P less than 0.05). The serum creatinine levels were 127 +/- 5 and 115 +/- 7 mumol/l (mean +/- SEM), respectively (N.S.). Two of the patients with normal serum creatinine had normal s-alpha 1m levels. There were positive linear correlations between s-alpha 1m and serum creatinine levels during stable renal function, rejection, cyclosporin-induced nephrotoxicity, and cytomegalovirus infections (r = 0.7-0.8, P less than 0.01-0.001) and between s-alpha 1m and beta 2 microglobulin (beta 2m) during the same conditions (r = 0.5-0.8, P less than 0.01-0.001). During infections, serum creatinine and beta 2m increased (P less than 0.001), but s-alpha 1m did not. S-alpha 1m values did not distinguish between rejection and cyclosporin-induced nephrotoxicity. It is concluded that s-alpha 1m might be a valuable complement to serum creatinine levels in the evaluation of renal function in renal transplant recipients.     

Expression of HLA-DR antigens on peripheral blood T lymphocytes and renal graft tubular epithelial cells in association with rejection

Since the expression of HLA-DR antigens on peripheral blood T lymphocytes and renal graft tubular epithelial cells may be associated with immunological stimulation, we investigated the expression of these antigens on blood T lymphocytes and graft tubular epithelium in 84 renal transplant patients. Peripheral blood T lymphocytes were monitored by flow cytometry during the first 3 months after transplantation. Since the DR+ lymphocytes were selected by a double-labeling technique used for the Leu2a phenotype, the majority of the DR+ lymphocytes were also Leu2a+ with a small percentage of unidentified Leu2a- lymphocytes. Forty-one patients were treated with cyclosporine (CsA) and 43 with azathioprine (Aza), while both groups received low-dose steroids. Frozen sections of 57 renal biopsies from 43 patients (21 on CsA and 22 on Aza) were stained for HLA-DR antigens. In the Aza group, clinical rejection episodes correlated with an increased percentage of DR+ peripheral lymphocytes (P = 0.0005), and the expression of DR antigens on graft epithelial cells (P less than 0.001). In the CsA group, no relation between the expression of DR antigens on blood lymphocytes and clinical rejection episodes was evident, and the correlation between tubular DR staining and clinical rejection episodes was weaker than in the Aza group (P = 0.03). In both the Aza and CsA group, an increase in DR+ peripheral lymphocytes correlated with positive staining of the renal tubular cells for HLA-DR antigens (P less than 0.001).     

Differentiation between renal allograft rejection and cyclosporine toxicity: a clinicopathological study

The differentiation between cyclosporine nephrotoxicity (CyN) and acute rejection (AR) still remains a matter of intensive research. In a retrospective study over the last 2 years, we assessed the clinical and histopathological data of 43 episodes of renal dysfunction in 39 renal transplant recipients immunosuppressed with cyclosporine (CyA). Ten episodes (23.2%) were identified as AR and 10 (23.2%) as acute CyN; in six cases (13.9%), signs of both AR and CyN were found. Fever (80%), oliguria (50%), and edema (50%) were prominent features in AR, but not in CyN. Renal blood flow was higher in the nephrotoxicity group and for corresponding degree of renal dysfunction. Significant hyperuricemia (greater than 8 mg/dL) was a prominent finding in CyN (80%) and to a lesser extent in AR (20%). The helper to suppressor cell ratio in the peripheral blood remained stable or slightly decreased in all cases with CyN, but increased in 70% of the cases with AR. CyN was associated with significantly higher whole blood CyA levels (P less than 0.005) and there was a positive correlation between plasma creatinine and CyA levels during the nephrotoxicity episodes (P less than 0.02). Diffuse mononuclear cell infiltrate was observed in 90% of the biopsies with AR and only in 20% with CyN (P less than 0.005). Concerning the extent of the tubular lesions, no significant differences were observed between the two groups. In contrast, vascular lesions such as arterial endothelial proliferation (P less than 0.05), hyalinosis (P less than 0.05), and glomerular capillary thrombi (P less than 0.05) were more commonly seen in nephrotoxicity biopsies.(ABSTRACT TRUNCATED AT 250 WORDS)     

The use of fine-needle intrarenal manometry in the management of renal transplant patients receiving cyclosporine

The pressure inside a renal transplant can be measured by means of a fine (25-G) needle passed into the kidney, and we have shown previously that a rise in pressure to more than 40 mmHg commonly occurs during rejection episodes. A rise was not observed in patients with cyclosporine nephrotoxicity or acute tubular necrosis, so we have now used this test prospectively as part of our management of 37 patients undergoing renal transplantation. Fine needle intrarenal pressure was recorded weekly during the first three weeks after transplantation, with more frequent measures taken in patients with deteriorating or absent renal function. Treatment was dictated by the result of these tests. Deteriorating function in a kidney registering a normal pressure was diagnosed as cyclosporine nephrotoxicity and the dose of cyclosporine was reduced appropriately. A pressure reading in excess of 40 mmHg was regarded as rejection--and, after obtaining a conventional needle biopsy of the kidney, antirejection treatment was commenced immediately. Nineteen episodes of nephrotoxicity were confirmed and there was only one false-positive result. Twenty-eight of twenty-nine rejection episodes (observed in twenty-three patients) were associated with a significant rise in intrarenal pressure and were treated appropriately. In six patients who were oliguric at the time, as a result of posttransplant acute tubular necrosis, this rise in pressure was the first indication of rejection. A high pressure was recorded on the first day that the creatinine rose in two-thirds of the cases. In the remainder the pressure was seen to rise more slowly, particularly when the rejection was of the chronic vascular type and was occurring two months or more after transplantation. Fine-needle intrarenal manometry accurately identified rejection episodes in newly transplanted patients--and, because the results were unaffected by cyclosporine nephrotoxicity and acute tubular necrosis, the test was of most value in monitoring patients with these conditions.     

Enzyme-linked immunosorbent assay for serum renal tubular antigen in kidney transplant patients

A mouse monoclonal antibody, specific for binding with the epithelial surface antigen in human renal proximal tubules, was produced by hybridoma culture. Using this antibody, an enzyme-linked immunosorbent assay was developed to measure the human renal tubular epithelial antigen (HRTE) concentrations in serum samples from 25 normal subjects and 66 consecutive renal allograft recipients. In 46 patients treated with azathioprine and prednisone, serum HRTE was elevated more than two-fold in 56 of 62 rejection episodes 2-5 days before the clinical diagnosis was made. Of the 56 rejection episodes, the antigen level fell to baseline after treatment in 44 steroid-responsive episodes, but it remained elevated in 8 steroid-resistant rejections, and it became undetectable 3-4 days after the initial elevation in 4 episodes in which allografts were lost to rejection. In 20 patients treated with cyclosporine and prednisone, all 25 rejection episodes demonstrated a greater than two-fold increase of serum HRTE 1-6 days prior to the diagnosis of rejection. The antigen level fell to baseline in 23 reversible rejection episodes, however serum HRTE remained elevated in 2 steroid-resistant patients whose grafts were lost to rejection. Cyclosporine nephrotoxicity without rejection was confirmed in 6 episodes, each of which demonstrated a more than two-fold increase in HRTE 2-4 days before toxicity was diagnosed. When the cyclosporine dose was reduced, the antigen level decreased as the serum creatinine declined. Serial determinations of serum HRTE in renal transplant recipients can provide valuable information for the early diagnosis and management of allograft rejection and cyclosporine nephrotoxicity.     

Proteomic-Based Identification of Cleaved Urinary β2-microglobulin as a Potential Marker for Acute Tubular Injury in Renal Allografts

Our aim is to develop noninvasive tests to monitor the renal allograft posttransplant. Previously, we have reported that an unbiased proteomic-based approach can detect urine protein peaks associated with acute tubulointerstitial renal allograft rejection. Identification of these proteins peaks by mass spectrometry demonstrated that they all derive from nontryptic cleaved forms of β2-microglobulin. In vitro experiments showed that cleavage of intact β2-microglobulin requires a urine pH < 6 and the presence of aspartic proteases. Patients with acute tubulointerstitial rejection had lower urine pH than stable transplants and healthy individuals. In addition, they had higher amounts of aspartic proteases and intact β2-microglobulin in urine. These factors ultimately lead to increased amounts of cleaved urinary β2-microglobulin. Cleaved β2-microglobulin as an indicator of acute tubular injury may become a useful tool for noninvasive monitoring of renal allografts.     

Urine excretion of protein HC in proteinuric glomerular diseases correlates to urine IgG but not to albuminuria.

BACKGROUND: Proteinuric glomerular diseases often are associated with tubulointerstitial injury, which imposes on the progression of renal failure. Tubular damage is partly referable to toxic effects on the tubular epithelial cells induced by filtered plasma proteins. Patients with nonselective proteinuria, that is, increased urine excretion of high-molecular-weight plasma proteins such as IgG in comparison to albumin, often have poor renal outcome. The present observational study examined correlations between the degree of tubular damage, measured by urine concentration of protein HC, and the levels of urine IgG and albuminuria. METHODS: Measurements of urine concentrations of IgG, albumin, and protein HC were performed in 56 proteinuric patients (33 males and 23 females) with nondiabetic glomerular diseases at the time of the diagnostic renal biopsy and at a mean of 49 follow-up months. RESULTS: A highly significant correlation between the urine IgG excretion and the urine protein HC concentration was found both at the start and at the end of the observational time (r = 0.74 and 0.65, respectively, P < 0.001). Furthermore, alterations in the urinary excretion of the two proteins in single patients correlated significantly to each other (r = 0.84, P < 0.001). The correlation between the degree of albuminuria and the protein HC excretion was significant at the time of kidney biopsy, but ceased to exist during the follow-up time. Stepwise linear regression analysis showed that in comparison with the creatinine clearance and albuminuria, only the changes in urinary IgG excretion were related to the corresponding changes in urinary protein HC excretion (r = 0.84 and r2 = 0.7, P < 0.001). CONCLUSION: The findings of the study suggest that the urinary protein HC concentration correlates to the degree of IgG-uria but not to the degree of albuminuria during the course of proteinuric glomerular disease. Whether this correlation is to be explained by an intrinsic toxic effect on tubular cells executed by IgG or perhaps by some other high molecular weight proteins, needs to be investigated further. However, the results contribute to the understanding of the poor renal survival in patients with glomerular diseases and nonselective proteinuria.     

Assessment of renal function in the early stages of nephrotoxicity induced by iodinated contrast media.

To determine whether there are early renal function parameters (RFP) which can be monitored to rapidly detect nephrotoxicity induced by contrast media (CM), we observed RFP in 16 patients with normal renal function before and after administration of CM. Forty-eight hours after diatrizoate meglumine administration, blood urea nitrogen (BUN) and serum creatinine (SCr) increased (p < 0.05). In all patients, acute tubular damage was revealed by early urinary RFP. Increases in levels of serum angiotensin-I-converting enzyme (ACE), beta(2)-microglobulin (beta(2)M) and urinary albumin (Alb) were associated with alterations in glomerular function. The changes in early RFP occurred earlier than those of BUN and SCr. The present study demonstrates that serum ACE, beta(2)M, urinary Alb, gamma-glutamyl-transpeptidase and N-acetyl-beta-D-glucosidase are sensitive parameters for the early assessment of subclinical nephrotoxicity induced by CM.     

Early computed colour echo Doppler imaging following renal transplantation

Thirty patients with renal allografts were monitored for 15 postoperative days by colour-coded Doppler imaging and categorized as stable, rejection, acute tubular necrosis and cyclosporine toxicity. All forms of graft dysfunction showed significantly raised resistance (P less than 0.01) and pulsatility (P less than 0.01) indices (RI and PI, respectively). It was not possible to use Doppler imaging to differentiate the cause of graft dysfunction, but stable grafts in patients with high cyclosporin levels had significantly higher RI (P less than 0.04) and PI (P less than 0.04) than similar grafts in patients with cyclosporine levels in the therapeutic range.     

An assessment of intrarenal hydrostatic pressure measurements in the diagnosis of acute renal allograft rejection

Postoperative intrarenal pressure measurements may be an aid to the diagnosis of acute renal transplant rejection, especially in patients treated with cyclosporine. Serial measurements of intrarenal pressure were made in 38 recipients using a fine-needle technique. Thirty-two intraoperative and 207 postoperative measurements were made, and 39 clinical rejection episodes (23 confirmed by biopsy) monitored. Intraoperative pressures in grafts with immediate function (37.4 +/- 4.0 mmHg, mean +/- SEM) were not significantly different from those with delayed function (30.9 +/- 4.8 mmHg), whereas postoperative pressures were greater (P less than 0.01) in kidneys with acute tubular necrosis (29.4 +/- 1.9 mmHg) than in functioning grafts (20.4 +/- 0.9 mmHg). Pressures recorded during clinical rejection episodes (44.3 +/- 2.3 mmHg) exceeded (P less than 0.001) those during quiescent periods (23.6 +/- 1.0 mmHg). During rejection episodes, higher pressures (P less than 0.01) were recorded from tender or palpably enlarged grafts (52.5 +/- 3.0 mmHg) than in the absence of these signs (36.3 +/- 3.1 mmHg), and patients whose transplants biopsies showed cellular rejection tended to have greater pressures (50.1 +/- 4.1 mmHg) than those with concomitant vasculopathy (36.4 +/- 3.9 mmHg), but the latter did not reach statistical significance. In 7 cases of cyclosporine toxicity the intrarenal pressure was 17.8 +/- 4.2 mmHg. Using a diagnostic cut off point of 40 mmHg, the investigation failed to recognize 26% of acute rejection episodes--and, in the presence of acute tubular necrosis, it wrongly categorized 21% of nonrejectors. While its predictive capacity was limited, the test may occasionally be helpful in the differentiation of cyclosporine toxicity and rejection in functioning kidneys.     

Acute renal allograft rejection is associated with increased levels of vascular endothelial growth factor in the urine

AIM: The purpose of this study was to assess whether measurement of urinary vascular endothelial growth factor (VEGF) could be adopted as a new non-invasive diagnostic tool for acute rejection following renal transplantation. METHODS: Urinary concentration of VEGF was determined by an enzyme-linked immunosorbent assay technique in 215 renal allograft recipients and 80 healthy controls. RESULTS: Subjects with acute rejection (n=67) excreted urinary VEGF at a significantly higher level (28.57+/-6.21, 95% CI: 16.18-40.97 pg/mumol creatinine) than those without acute rejection. This included subjects with stable renal function and no abnormal histological findings (n=119), acute tubular necrosis (n=15), chronic allograft nephropathy (n=14) and healthy controls (n=80). Using a urinary VEGF/creatinine ratio of 3.64 pg/micromol as the cut-off point, the sensitivity and specificity for diagnosing acute rejection were 85.1 and 74.8%, respectively (P<0.001). Patients with steroid-resistant acute rejection had significantly greater urinary VEGF concentration than patients with steroid-sensitive acute rejection (42.09+/-10.00 vs 9.74+/-2.63 pg/micromol creatinine, P<0.001). Patients with graft loss after acute rejection had significantly greater urinary VEGF concentration than patients with reversible acute rejection (106.66+/-38.60 vs 19.46+/-4.13 pg/micromol creatinine, P=0.001). Using a urinary VEGF/creatinine ratio of 22.48 pg/micromol as the cut-off point, the sensitivity and specificity of the prediction to graft loss after acute rejection were 85.7% and 78.3%, respectively (P=0.001). CONCLUSION: This study demonstrates that the monitoring of urinary VEGF may be a useful non-invasive approach for the detection of acute rejection. Additionally, urinary VEGF levels were shown to predict the response to anti-rejection therapy and to predict a poor outcome after acute rejection.