A fuller understanding of pancreatic neuroendocrine tumours combined with aggressive management improves outcome

BACKGROUND

Neuroendocrine tumours of the pancreas (PNETs) represent 1-2% of all pancreatic tumours. The terms 'islet cell tumours' and 'carcinoids' of the pancreas should be avoided. The aim of this review is to offer an overview of the history and diagnosis of PNETs followed by a discussion of the available treatment options.

METHODS

A search on PubMed using the keywords 'neuroendocrine', 'pancreas' and 'carcinoid' was performed to identify relevant literature over the last 30 years.

RESULTS

The introduction of a revised classification of neuroendocrine tumours by the World Health Organisation (WHO) in 2000 significantly changed our understanding of and approach to the management of these tumours. Advances in laboratory and radiological techniques have also led to an increased detection of PNETs. Surgery remains the only treatment that offers a chance of cure with increasing number of non-surgical options serving as beneficial adjuncts. The better understanding of the behaviours of PNETs together with improvements in tumour localisation has resulted in a more aggressive management strategy with a concomitant improvement in symptom palliation and a prolongation of survival.

CONCLUSION

Due to their complex nature and the wide range of therapeutic options, the involvement of specialists from all necessary disciplines in a multidisciplinary team setting is vital to provide optimal treatment of this disease.

Obtaining explicit consent for the use of archival tissue samples: practical issues

BACKGROUND

Over the past few years, research ethics committees have increasingly demanded explicit consent before archival tissue samples can be used in research projects. Current UK guidance in this area requires an assessment of whether it is "practical" to obtain explicit consent. Ethics committees have little experience or evidence to help them to judge what is "practical" in this context.

METHODS

We attempted to obtain general consent for research use of surplus tissue from renal transplant biopsies from the entire patient population of the renal transplant unit in Leicester. The nature of this patient population would be expected to facilitate this task.

RESULTS

A total of 495 letters were sent. Attempts were made to contact non-responders when they attended the outpatient clinic. One year after the initiation of the project, the opinions of 26% of the patients had still not been ascertained.

CONCLUSIONS

The results confirm that the vast majority of patients are happy for "surplus" biopsy material to be used for research; the situation does not parallel the use of autopsy tissue. A requirement to obtain explicit consent for the study of archival tissue is likely, however, to block or at least seriously delay research, which is contrary to the public interest and specifically may harm the interests of the patients concerned. In the UK, the problem of tissue being used against the wishes of the donor has now been largely replaced by the problem of prohibition of tissue use against the wishes of the donor.

Randomized clinical trial of the effect of microemulsion cyclosporin and tacrolimus on renal allograft fibrosis

BACKGROUND

The aim of this study was to compare the effect of Neoral cyclosporin- and tacrolimus-based therapy on the development of renal allograft fibrosis (chronic allograft nephropathy; CAN) in a prospective randomized trial.

METHODS

A total of 102 patients undergoing renal transplantation were randomized to immunosuppression with either microemulsion cyclosporin (Neoral; 15 mg per kg per day adjusted to whole-blood trough concentrations of 200-300 ng/ml) or tacrolimus (0.2 mg per kg per day adjusted to whole-blood trough levels of 8-15 ng/ml) in conjunction with steroids, or at a lower dose (7 mg per kg per day and 0.1 mg per kg per day respectively) with the addition of azathioprine for non-heart-beating renal transplant recipients. Renal transplant interstitial fibrosis was quantified using computerized histomorphometric measurement of picrosirius red-stained 1-year protocol renal transplant biopsies. Levels of interstitial fibrosis were compared in relation to observed efficacy and toxicity profiles of the two drugs.

RESULTS

There was a significant increase in allograft interstitial fibrosis in the patients treated with Neoral compared with those given tacrolimus. There was no significant difference in the demographic characteristics between the patient groups or in the incidence of acute rejection (Neoral 36 per cent versus tacrolimus 35 per cent) or steroid-resistant rejection (both 10 per cent) between the two drugs. There was a higher incidence of insulin resistance in the tacrolimus group (post-transplant diabetes mellitus, glucose tolerance testing) but this was not statistically significant. Neoral was associated with a significant increase in total cholesterol (P = 0.030) and low-density lipoprotein (P = 0.021) levels, which persisted throughout the study period.

CONCLUSION

Despite equivalent efficacy and pretransplantation risk factors for CAN, Neoral was associated with increased allograft fibrosis and significantly higher serum low-density lipoprotein cholesterol levels compared with tacrolimus.

The development and evaluation of the UK national telepathology network

AIMS

As technology advances and costs fall, it may be anticipated that soon every histopathologist will expect to be able to exchange electronic images with colleagues. Arguing that the value of a network increases as more people are connected, we sought to install a simple, low-cost telepathology system into any histopathology laboratory which requested it within the UK.

METHODS AND RESULTS

We assumed that laboratories had microscopes, computers and internet access. We offered low-cost video cameras, video input cards, software and training to any histopathology department requesting installation, limited only by resources supplied by the UK government. We also established central servers and a website with 'help' files. After 1 year we studied system use and pathologists' opinions by circulating a questionnaire. Installations were completed in 35 laboratories; there are currently 66 registered users of the system, with 16 identified 'experts' covering most organ systems. Serious difficulties were caused by institutional firewalls and reluctance of local information technology (IT) staff to make changes to facilitate the installation or to help resolve subsequent network problems. After installation, many of the telepathology systems remain unused. Concerns were expressed about image quality, though mainly by pathologists who had not used the system for diagnostic work. The system remains available, but the level of use is low.

CONCLUSIONS

This project has not achieved its aims. The reasons are complex, but mainly relate to human attitudes. Pathologists with excessive workloads were reluctant to use time to learn new skills which were not directed to reducing workload. IT staff did not perceive the project as part of their routine work. There were also numerous technological problems, but although image quality was cited by many, it was not a complaint of those who actively used the system. These problems have not been encountered by previous projects which involved small groups of committed enthusiasts.

International variation in the interpretation of renal transplant biopsies: report of the CERTPAP Project

BACKGROUND

The Banff working formulation of renal transplant pathology is intended to have international application. There remains a need to develop methods to harmonize the application of such grading systems between laboratories. Banff grades do not always permit precise management decisions to be made. Alternative schemes have been devised for the diagnosis of acute rejection, but there have been no independent tests of the different approaches.

METHODS

Sections from 55 renal transplant biopsies were circulated around the laboratories of 22 major transplant units for the Convergence of European Renal Transplant Pathology Assessment Procedures (CERTPAP) Project. Participating pathologists were asked to grade 32 different histological features, without any clinical information. After each circulation of five cases, feedback was provided to participants. Statistical evidence of improvement in interobserver variation was sought. At the end of the study, correlations with the original clinicopathological diagnosis were sought.

RESULTS

Interobserver variation was greater than has previously been reported. For every feature studied, some pathologists consistently under-grade or over-grade. There was relatively little evidence of improvement in interobserver variation as a result of the feedback system. No single feature permitted a reliable diagnosis of acute rejection. Applying the Banff and CCTT schemas to the histological grades showed no clear diagnostic advantage for either system, but a simple computer-based inference network, which combined data from 12 histological features, out performed either approach. Within the "protocol" biopsies studied, long-term survival correlated better with "acute" than with "chronic" histological features.

CONCLUSIONS

These results do not undermine the value of the Banff classification, but they demonstrate a need for caution when translating biopsy results between institutions. It is obvious that evaluation of biopsies in multicenter trials must be done in one center. In the management of individual patients, the need to interpret Banff grades in the light of local experience and clinical information is stressed.

Research using human tissues--a crisis of supply?

It is a paradox that the pursuit of ethical practice can sometimes produce distinctly unethical results. Pathologists seek to study diseased human tissues for the benefit of mankind, but in the UK there has been a sudden restriction in the availability of this basic resource, supposedly on ethical grounds. This was triggered by adverse publicity about the inappropriate retention of whole organs at paediatric post-mortem, but the reaction has spread to influence the use of 'surgical waste' left over after routine analysis of therapeutic resections, diagnostic biopsies, and even blood samples. The use of such material for research is being restricted, and its use in teaching and laboratory quality control is being questioned. This has occurred despite the facts that public opinion favours using such 'waste' material for research; that the tissues would otherwise be incinerated; and that until very recently, such tissues were regarded as having been 'abandoned' by the patient. This review attempts to chart how this dramatic change has occurred. It then considers some of the ethical problems in using such 'surplus' tissues and proposes mechanisms by which this valuable resource can remain available for most biomedical research, while maintaining or enhancing the autonomy of individual patients. This crisis has shown a tendency for regulatory authorities to apply very restrictive, oversimplified rules, without due consideration of the character of each project. The motivation is to avoid the possibility of media criticism, even though such rules block ethically sound work which is of value to all, including the individuals whose protection is supposedly being sought. The moral need for logical ethical arguments instead of such 'one size fits all' regulations is emphasized.

Sub-clinical acute rejection detected using protocol biopsies in patients with delayed graft function

Acute rejection in renal transplants is difficult to diagnose when patients have delayed graft function (DGF) in the early post-transplant period. In this study protocol, renal transplant biopsies were performed in an attempt to detect sub-clinical acute rejection episodes. Eighty-three patients were eligible for the study, of whom 33 had DGE All had protocol renal transplant biopsies performed under ultrasound control at 7 days post-transplant, and those with DGF had further biopsies weekly until the graft functioned. All histologically confirmed acute rejection episodes were treated. Sub-clinical acute rejection was detected in 6/33 (18%) patients with DGF compared to 2/50 (4%) in the other patients (P < 0.05). Borderline rejection was present in 4/33 (12%) and 4/50 (8%) patients, respectively. Because of the high detection rate of sub-clinical acute rejection and the low morbidity of renal transplant biopsies, their use is recommended in patients with DGF.

Differential effects of cyclosporin and tacrolimus on the expression of fibrosis-associated genes in isolated glomeruli from renal transplants

BACKGROUND

Chronic allograft nephropathy is characterized by an excessive accumulation of extracellular matrix proteins leading to glomerular and interstitial fibrosis. The aim of this study was to determine the effects of two different immunosuppressive agents (cyclosporin and tacrolimus) on the expression of the genes controlling extracellular matrix deposition in renal transplant glomeruli.

METHODS

Fifty-one renal transplant recipients were randomized to receive immunosuppression with either microemulsion cyclosporin or tacrolimus. Isolated glomeruli were plucked from protocol transplant biopsies performed 1 week, 3 months and 6 months after transplantation. Expression of the genes for collagen IValpha2, collagen III, matrix metalloproteinase 2, tissue inhibitor of metalloproteinases (TIMP) 1 and TIMP-2, tenascin and transforming growth factor (TGF) beta1 was studied by quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

The expression of messenger RNA (mRNA) for collagen III and TIMP-1 was significantly higher in patients receiving cyclosporin therapy than in those having tacrolimus (P < 0.01); this finding was accounted for by differences in the biopsy material at 1 week. A significant difference in collagen III, TIMP-1 and TIMP-2 mRNA expression was also detected between patients depending on the source of renal donor (cadaveric or living). There were no significant differences in the level of glomerular TGF-beta1.

CONCLUSION

The data provide new in vivo evidence that tacrolimus may exert a less fibrogenic influence on transplant glomeruli than cyclosporin.

Incidental adult nesidioblastosis after distal pancreatectomy for endocrine microadenoma

Persistent hyperinsulinaemic hypoglycaemia (nesidioblastosis) presenting with hypoglycaemia is extremely rare in adults. The features are suggestive of an insulinoma with a vague presentation and delayed diagnosis. We describe a report of adult nesidioblastosis in association with a pancreatic endocrine microadenoma.

IgA myeloma presenting as Henoch-Schönlein purpura with nephritis

IgA nephropathy (IgAN) and Henoch-Schönlein purpura (HSP) are both characterized by IgA-mediated tissue injury, including mesangial proliferative glomerulonephritis. Abnormalities of IgA1 glycosylation are described in IgA nephropathy and HSP nephritis. IgA-antineutrophil cytoplasmic antibodies (ANCA) have been inconsistently described in the serum of patients with HSP. In IgA myeloma, the paraprotein-mediated renal lesion is typically cast nephropathy; IgAN or HSP have only rarely been reported in myeloma even when an IgA paraprotein is circulating in large concentrations. We report the case of a 50-year-old man with IgA myeloma who presented with HSP including nephritis and rapidly progressive renal failure. His IgA1 had altered O-glycosylation in the pattern seen in IgAN and also contained an IgA-ANCA. This case adds further weight to the evidence that IgA1 O-glycosylation abnormalities predispose to mesangial IgA deposition and also that IgA-ANCA may have a pathogenic role in the development of HSP.

A prospective randomized trial of three different sizes of core-cutting needle for renal transplant biopsy

BACKGROUND

Needle-core biopsy remains one of the most important investigations in cases of renal allograft dysfunction. The size and quality of the biopsy material are likely to be important factors in achieving an accurate diagnosis. The aim of this study was to compare the success and complication rates of renal transplant biopsy procedures using three differently sized needles.

METHODS

One hundred renal allograft recipients undergoing transplant biopsy using an automated needle core method were randomized to a 14, 16, or 18 gauge (G) needle. The size of each biopsy core was measured, and the presence or absence of renal cortical and medullary tissue and the number of glomeruli were recorded. Assessments of the ease with which the procedure was performed, the diagnostic usefulness of the biopsy material, and the discomfort associated with the procedure were made using verbal response and linear analog scales.

RESULTS

Fourteen G biopsy cores (N = 33) were larger than both 16G (N = 33) and 18G (N = 34) cores and contained more gomeruli (mean number for 14G, 16G, and 18G = 15, 11 and 9, respectively). There were no differences in the ease of use of the three needle types, but scores for diagnostic usefulness were higher for 14G versus 18G and 16G versus 18G. The 14G needle was associated with significantly more pain than the two smaller needles when this was assessed using a linear analog score. Macroscopic hematuria occurred in eight patients, but there were no differences in complications rates between the three groups.

CONCLUSIONS

All three needle sizes are safe for use in renal allograft biopsy using a semiautomated biopsy gun. The larger needles provide more tissue and glomeruli and, thus, are more diagnostically useful. Use of a 14G needle may be associated with more pain, and the 16G needle appears to offer the best compromise between diagnostic usefulness and patient acceptability.

Acp. Best practice no 160. Renal biopsy specimens

Taking a kidney biopsy is not a trivial procedure. The sample is almost invariably smaller than the pathologist would like. Investigation usually requires division into even smaller samples to permit the application of specialist techniques. In some cases the biopsy is taken not for diagnosis, but to assess the extent of tissue damage. The clinical need is sometimes extremely urgent. These features all underline the crucial importance of collaboration between pathologist and nephrologist if maximum benefit is to be obtained from such very small samples. Consequently, in deciding what to do with a renal biopsy, flexibility and thought are required rather than a single prescribed list of procedures. This article, written after extensive international consultation, represents an attempt to define current best practice in the laboratory handling of renal biopsy specimens, while not neglecting the need to tailor processing to the individual needs of each case.

Inactive matrix metalloproteinase 2 is a normal constituent of human glomerular basement membrane. An immuno-electron microscopic study

Remodelling of the extracellular matrix requires tight control not only of matrix synthesis, but also of matrix degradation. Control of matrix degradation is achieved mainly through the matrix metalloproteinase (MMP) enzymes. In the glomerulus, MMP-2 and MMP-9 are believed to be particularly important, as they have activity against type IV collagen. This study has demonstrated by immuno-electron microscopy that most of the immunoreactivity for MMP-2 in the normal glomerulus is located within the glomerular basement membranes and mesangial matrix. mRNA for MMP-2 is also detectable in normal glomeruli, but the other main gelatinase, MMP-9, could not be localized by immuno-electron microscopy. In the normal glomerulus, it seemed likely that MMP-2 is present in an inactive form. To confirm this, in situ zymography was carried out using frozen sections of normal kidney. Baseline activity of normal kidney was relatively weak, but this was dramatically increased by chemical activation of metalloproteinases. The results imply that MMP-2, in an inactive form, is a normal constituent of the extracellular matrix and glomerular basement membranes. Activation would presumably render the matrix 'self-degrading'; membrane-bound MMPs (MT-MMPs) seem particularly likely to be involved in leukocyte penetration of basement membranes in inflammation.

A neural network approach to the biopsy diagnosis of early acute renal transplant rejection

AIMS

To develop and test a neural network to assist in the histological diagnosis of early acute renal allograft rejection.

METHODS AND RESULTS

We used three sets of biopsies to train and test the network: 100 'routine' biopsies from Leicester; 21 selected difficult biopsies which had already been evaluated by most of the renal transplant pathologists in the UK, in a study of the Banff classification of allograft pathology and 25 cases which had been classified as 'borderline' according to the Banff classification in a review of transplant biopsies from Oxford. The correct diagnosis for each biopsy was defined by careful retrospective clinical review. Biopsies where this review did not provide a clear diagnosis were excluded. Each biopsy was graded for 12 histological features and the data was entered into a simple single layer perception network, designed using the MATLAB neural network toolbox. Results were compared with logistic regression using the same data, and with 'conventional' histological diagnosis. If the network was trained only with the 100 'routine' cases, its performance with either of the other sets was poor. However, if either of the 'difficult' sets was added to the training group, testing with the other 'difficult' group improved dramatically; 19 of the 21 'Banff' study cases were diagnosed correctly. This was achieved using observations made by a trainee pathologist. The result is better than was achieved by any of the many experienced pathologists who had previously seen these biopsies (maximum 18/21 correct), and is considerably better than that achieved by using logistic regression with the same data.

CONCLUSION

A neural network can provide a considerable improvement in the diagnosis of early acute allograft rejection, though further development work will be needed before this becomes a routine diagnostic tool. The selection of cases used to train the network is crucial to the quality of its performance. There is scope to improve the system further by incorporating clinical information. Other related areas where this approach is likely to be of value are discussed.

Vascular endothelial growth factor mRNA expression in minimal change, membranous, and diabetic nephropathy demonstrated by non-isotopic in situ hybridisation

AIM

To investigate vascular endothelial growth factor (VEGF) mRNA expression in glomerular disease in the context of heavy proteinuria.

METHODS

Non-radioisotopic in situ hybridisation was performed using a cocktail of 12 deoxyoligonucleotides complementary to VEGF mRNA labelled during solid phase synthesis with 2,4-dinitrophenyl. Archival renal biopsies were studied from cases of minimal change nephropathy, membranous nephropathy, diabetic nephropathy, and controls, matched for age, sex, race, and storage time. Hybrid detection used NBT/BCIP colorimetric development.

RESULTS

More VEGF mRNA positive glomerular cells per unit cross sectional diameter were seen in minimal change nephropathy (mean (SEM), 19.35 (1.5)) compared with controls (12.6 (1.73)), p < 0.01. In contrast, fewer were seen in diabetic nephropathy (5.93 (0.97)) compared with controls (9.97 (1.25)), p < 0.03. Analysis of membranous nephropathy (10 (1.62)) showed no difference from controls (10.98 (1.51)), NS. In addition, in minimal change nephropathy there was a significant correlation between 24 hour protein excretion at the time of biopsy and the number of VEGF mRNA cells per glomerulus (r = 0.08, p = 0.01).

CONCLUSIONS

Using non-radioisotopic in situ hybridisation, VEGF mRNA is almost exclusively expressed by visceral glomerular epithelial cells. Abnormal numbers of cells are seen in both minimal change and diabetic nephropathy. As VEGF exists in a number of functionally distinct isoforms, further study of qualitative VEGF isoform expression in diagnostic groups is indicated.

Comparison of the expression of fibrosis-associated genes in glomeruli after renal transplantation between conventional cadaveric and non-heart-beating donors

BACKGROUND

The main difference between cadaveric heart-beating donors and non-heart-beating donors (NHBDs) is the degree of warm ischaemia to which the kidney is subjected. This study was designed to see if this affected the expression of fibrosis-associated genes in the early period after transplantation.

METHODS

A series of 29 cadaveric and 19 NHBD renal transplants was studied. Patients underwent protocol needle-core renal transplant biopsies at 1 week, 3 months and 6 months after transplantation. At least two individual glomeruli were isolated from each biopsy. Messenger RNA was extracted and genes of interest were amplified by reverse transcriptase-polymerase chain reaction, then quantified in an enzyme-linked immunosorbent assay system.

RESULTS

Delayed graft function was common in NHBD (17 of 19) compared with cadaveric transplants (six of 29) (P < 0.0001). Acute rejection rates were similar. The level of tissue inhibitor of metalloproteinase 1, an inhibitor of extracellular matrix degradation, was higher in kidneys from NHBDs at 1 week (P = 0.02). There were no other statistically significant differences in the expression of fibrosis-associated genes between the two groups.

CONCLUSION

Although the increased ischaemic injury in kidneys retrieved from NHBDs leads to a higher rate of delayed graft function, this does not translate into increased expression of fibrosis-associated genes after the first week.

Intragraft expression of transforming growth factor beta1 gene in isolated glomeruli from human renal transplants

BACKGROUND

Experimental evidence suggests that transforming growth factor (TGF) beta1 is a fibrogenic cytokine. The histopathological changes of chronic renal allograft nephropathy are dominated by fibrotic changes and TGF-beta may have an important aetiological role. This study investigated the relationship between intragraft TGF-beta gene expression and extracellular matrix protein deposition in human renal allografts.

METHODS

Sixteen cadaveric renal transplant recipients immunosuppressed with cyclosporin and steroids were studied. Individual glomeruli were isolated from protocol needle-core biopsies and, following messenger RNA extraction, intragraft gene expression was studied by reverse transcriptase-polymerase chain reaction. Collagen III deposition in these renal transplant biopsies was examined by immunohistochemistry and quantified by computerized histomorphometry.

RESULTS

There was a positive correlation between renal cortical collagen III immunostaining and the levels of glomerular complementary DNA for TGF-beta1.

CONCLUSION

TGF-beta1 is a profibrotic influence in human renal transplants. The methods described should prove of benefit in investigating the mechanisms of chronic renal allograft damage.

Biphasic role for nitric oxide in experimental renal warm ischaemia-reperfusion injury

BACKGROUND

Whilst nitric oxide has a clearly defined role in renal haemostasis, debate continues over its pathophysiology. This study investigated the function of nitric oxide in a model of renal warm ischaemia-reperfusion injury.

METHODS

Rats underwent bilateral renal warm ischaemia (45 min) after pretreatment with nitric oxide donors, nitric oxide synthase (NOS) inhibitors or saline (control). Following reperfusion (20 min) a unilateral nephrectomy was performed to measure renal nitric oxide (as nitroxides) and oxidative DNA and protein damage. Renal function was measured on days 2 and 7 before terminal nephrectomy for analysis and morphology.

RESULTS

The increase in renal nitric oxide level seen early in reperfusion (20 min) (P < 0.01) was prevented by inhibition of constitutive (cNOS) but not inducible (iNOS) NOS. The increase in oxidative damage (P < 0.01) was exacerbated by nitric oxide donors (P < 0.01) but ameliorated by NOS inhibition (P < 0.01). Control nitric oxide remained increased through to day 7 (P < 0.01) but was reduced by nitric oxide donors and cNOS inhibitors (P < 0.05). Oxidative damage returned towards normal in the control group, whereas both DNA and protein damage persisted following NOS inhibition (P < 0.01).

CONCLUSION

Inhibition of the postischaemic increase in the level of nitric oxide was associated with an early decrease in, but eventual exacerbation of, oxidative damage. This suggests the prolonged increase in renal nitric oxide concentration was cytoprotective overall.

Computerized histomorphometric assessment of protocol renal transplant biopsy specimens for surrogate markers of chronic rejection

BACKGROUND

Chronic transplant rejection has emerged as the commonest cause of long-term renal allograft failure, and early identification of those grafts at risk could allow the targeting of specific therapies aimed at delaying this process. This study explores the usefulness of quantitative immunohistochemistry in defining biopsy-based surrogate markers of allograft damage.

METHODS

A consecutive series of 52 renal transplant recipients immunosuppressed with cyclosporine were studied. Needle core transplant biopsies were performed at 1, 3, and 6 months postoperatively. Immunostaining for collagen III, and smooth muscle actin, tenascin, and infiltrating leukocytes was performed using an indirect immunoperoxidase technique. The interstitial area stained (%) was measured using a semiautomatic image analysis system. The results were related to glomerular filtration rates (GFR) measured at 6, 12, and 24 months after transplantation using rank correlation coefficients.

RESULTS

The area fraction of immunostained collagen III correlated with 6-month GFR (r=-0.42, P=0.005) and was predictive of 12-month GFR (r=-0.32, P=0.03). An area fraction of immunostained collagen III of >40% at 6 months was associated with a significantly lower GFR at 24 months, compared with a percentage area of < or =40% (31+/-4 versus 45+/-4 ml/min/1.73 m2, P=0.01). Furthermore, a collagen III of >40% at 6 months identified patients who were at risk of progressive deterioration in graft function.

CONCLUSIONS

Grafts with poorer long-term function can be predicted using 6-month protocol biopsy specimens immunostained for collagen III. This should prove to be a useful ad interim surrogate marker of allograft damage in studies addressing the effects of new immunosuppressive agents on the development of chronic rejection.

Glomerular expression of nephrin is decreased in acquired human nephrotic syndrome

BACKGROUND

Nephrin recently has been identified as a putative adhesion molecule, expressed in the glomerulus, in which mutations cause congenital nephrotic syndrome of Finnish type. We sought to determine whether expression of nephrin is altered in human glomeruli in patients with acquired nephrotic syndrome.

METHODS

We performed PCR amplification of nephrin cDNA, using cDNA previously prepared from single human glomeruli plucked fresh from the surface of human renal biopsies. We had available four cases of nephrotic syndrome (one membranous, three minimal change) and six normal controls. PCR product quantitation was by gel densitometry, confirmed by enzyme-linked immunosorbent assay using a specific oligonucleotide probe. Results were corrected for reaction efficiency and glomerular cellularity by expression as a ratio to levels of the 'housekeeping gene' glyceraldehyde phosphate dehydrogenase.

RESULTS

Glomerular levels ofnephrin mRNA are significantly decreased in cases of minimal change nephrotic syndrome. An apparent reduction was also seen in the single case of membranous nephropathy which was available for study.

CONCLUSIONS

Abnormalities of nephrin expression appear to be associated with acquired as well as congenital causes of human nephrotic syndrome.

Proteinuria induces tubular cell turnover: A potential mechanism for tubular atrophy

BACKGROUND

Proteinuria and tubular atrophy have both been closely linked with progressive renal failure. We hypothesized that apoptosis may be induced by tubular cell exposure to heavy proteinuria, potentially leading to tubular atrophy. Apoptosis was studied in a rat model of "pure" proteinuria, which does not induce renal impairment, namely protein-overload proteinuria.

METHODS

Adult female Lewis rats underwent intraperitoneal injection of 2 g of bovine serum albumin (BSA, N = 16) or sham saline injections (controls, N = 8) daily for seven days. Apoptosis was assessed at day 7 in tissue sections using in situ end labeling (ISEL) and electron microscopy. ISEL-positive nuclei (apoptotic particles) were counted in blinded fashion using image analysis with NIH Image. Cell proliferation was assessed by detection of mRNA for histone by in situ hybridization, followed by counting of positive cells using NIH Image.

RESULTS

Animals injected with saline showed very low levels of apoptosis on image analysis. BSA-injected rats had heavy proteinuria and showed both cortical and medullary apoptosis on ISEL. This was predominantly seen in the tubules and, to a lesser extent, in the interstitial compartment. Overall, the animals injected with BSA showed a significant 30-fold increase in the number of cortical apoptotic particles. Electron microscopy of tubular cells in a BSA-injected animal showed a progression of ultrastructural changes consistent with tubular cell apoptosis. The BSA-injected animals also displayed a significant increase in proximal tubular cell proliferation. This increased proliferation was less marked than the degree of apoptosis.

CONCLUSION

Protein-overload proteinuria in rats induces tubular cell apoptosis. This effect is only partially balanced by proliferation and potentially provides a direct mechanism whereby heavy proteinuria can induce tubular atrophy and progressive renal failure.

New model of renal warm ischaemia-reperfusion injury for comparative functional, morphological and pathophysiological studies

BACKGROUND

Renal warm ischaemia-reperfusion injury is pertinent to vascular and transplant surgery. While established models provide functional and morphological data the authors wanted to be able to correlate this with the underlying pathophysiology at any chosen time point, thus allowing future interventional effects on reperfusion injury to be evaluated.

METHODS

In a rodent model bilateral renal warm ischaemia (15-60 min) and then reperfusion (20 or 80 min) before nephrectomy allowed for analysis of early reperfusion pathophysiology. The remaining kidney provided functional data (glomerular filtration rate (GFR)) at days 2 and 7 before nephrectomy for late analysis and morphology using a new grading system.

RESULTS

Acceptable survival rate (ten of 12 animals) was seen with up to 45 min of warm ischaemia. Renal function was impaired at day 2 following 30-60 min of warm ischaemia (P< 0.01) and day 7 in the 45- and 60-min groups (P < 0.05 and P < 0.01 respectively). Strong correlation existed between duration of ischaemia and GFR at day 2 (r2=0.88) and day 7 (r2=0.95). Histological damage in the cortical tubules was evident in the 45- and 60-min groups (P< 0.01).

CONCLUSION

This new model allowed comparative functional, morphological and pathophysiological studies while minimizing the number of animals required. Overall 45 min of warm ischaemia gave significant, recoverable injury and is recommended for investigating renal reperfusion injury.

Nitric oxide generation is increased in experimental renal warm ischaemia-reperfusion injury

BACKGROUND

Nitric oxide has a clearly defined place in normal renal homoeostasis while there is a continuing debate as to its role under pathophysiological conditions. This study investigated the role of nitric oxide in a model of renal warm ischaemia-reperfusion injury.

METHODS

Groups of rats underwent bilateral renal warm ischaemia (for 15-60 min) followed by reperfusion (20 or 80 min) before unilateral nephrectomy for measurement of renal nitric oxide (as nitroxides) and oxidative damage. Renal function was measured on days 2 and 7 before killing and nephrectomy. A further group received the nitric oxide synthase inhibitor N(G)-nitro L-arginine methyl ester (L-NAME; 50 mg per kg body-weight) before induction of warm ischaemia.

RESULTS

In early reperfusion there was a correlation between the duration of warm ischaemia (15-45 min) and renal nitrate (r2=0.97) which increased from a mean(s.e.m.) baseline value of 95(5.9) to 208(17.3) nmol per mg protein following 45 min of warm ischaemia. Levels were further raised at 80 min and maintained through to day 7 (241(12.5) nmol per mg protein in 45-min group). This rise was attenuated by L-NAME (P< 0.01) as was the early rise in oxidative damage seen otherwise. By day 7, however, oxidative damage was increased (all P< or = 0.01).

CONCLUSION

Renal nitric oxide increased early in recoverable warm ischaemia-reperfusion injury and remained raised to day 7. Nitric oxide synthase inhibition ameliorated early but exacerbated late damage suggesting that the early burst of nitric oxide is cytotoxic but that overall nitric oxide may exert a cytoprotective effect.

Visceral glomerular epithelial cell DNA synthesis in experimental and human membranous disease

BACKGROUND

Membranous nephropathy (MN) is a 'non-proliferative' glomerulonephritis. However, visceral glomerular epithelial cell (vGEC) proliferating cell nuclear antigen staining and increased glomerular histone mRNA in passive Heymann nephritis (PHN), suggest that vGECs may enter the cell cycle and undergo DNA synthesis. We used in situ hybridisation for histone mRNA, an S-phase specific marker, to investigate this possibility and identify the cellular origin of histone mRNA in PHN and MN.

METHODS

PHN was induced in 16 Sprague-Dawley rats. There were 8 saline/serum controls. 12 animals were sacrificed on days 5 and 10. Renal biopsies from 10 proteinuric cases with MN and matched controls were studied.

RESULTS

Day-5 Heymann animals demonstrated more S-phase cells/glomerulus than controls (0.53 +/- 0.09 vs. 0.195 +/- 0.045; p < 0.01). Glomerular S-phase cells were also increased in patients compared to controls (0.24 +/- 0.07 vs. 0.04 +/- 0.018; p < 0.03). In both experimental and human MN, the peripheral location and morphology of glomerular histone mRNA-positive cells was typical of vGECs.

CONCLUSION

The results in PHN indicate that vGECs recently injured with antibody and complement enter into the cell cycle and undergo DNA synthesis. The S-phase vGECs in MN may indicate the persistence of immune injury. Whether or not this process leads to cell replication is open to question.

Reproducibility in the quantification of mRNA levels by RT-PCR-ELISA and RT competitive-PCR-ELISA

The use of reverse transcription (RT) PCR for relative quantitation of gene transcripts relies on the reproducibility of the individual RT, PCR and product measurement steps. Semi-competitive RT-PCR (RT-cPCR) uses an internal competitor template in the PCR step to improve quantitation. We have surveyed the reproducibility of RT, PCR, RT-cPCR and measurement, amplifying the glyceraldehyde-3-phosphate dehydrogenase "housekeeping" gene from isolated renal glomeruli. We used an enzyme-linked immunosorbent assay (ELISA) to quantify PCR products. We also report our PCR-based method for constructing a competitor DNA identifiable independently of the native product. Our results show that the entire RT-PCR and ELISA process had a standard deviation (SD) of less than 10% (n = 10). This compared to an SD of less than 13% (n = 10) in PCR and ELISA. The SD for ELISA alone was less than 11% (n = 10). RT-cPCR quantitation gave an SD of approximately 15% (n = 10). These results support the use of standard RT-PCR for the relative quantitation of mRNA. RT-cPCR is also suited to relative quantitation, but it is also independent of the amplification saturation curve and permits the identification of differences in cellularity between samples.

Diagnosis of early acute renal allograft rejection by evaluation of multiple histological features using a Bayesian belief network

BACKGROUND AND AIMS

The development of the Banff classification of renal transplant pathology has allowed the standardisation of approaches to transplant biopsy histology and reduced interobserver and interdepartmental variation. The usefulness of the Banff classification in the diagnosis of acute rejection has previously been tested by sending sections from 21 "difficult" biopsies to almost all of the renal transplant pathologists in the UK. Although the Banff classification improved reproducibility, the accuracy of diagnosis of early acute rejection was unchanged from the "conventional" approach. Perhaps this is because in making a diagnosis of acute rejection, the Banff classification uses only two features: tubulitis and intimal arteritis. To include more features on a systematic basis would be laborious for a human observer. Therefore, a Bayesian belief network was developed for this task.

METHODS

The network was initialised with observations from 110 transplant biopsies. Its performance was then tested on 21 biopsies that had been seen by 37 different renal transplant pathologists in an earlier study. These biopsies had been selected to represent histologically difficult problems but, in retrospect, they all had clear diagnoses of rejection or non-rejection on clinical grounds.

RESULTS

Using the Bayesian belief network, a relatively inexperienced pathologist made 19 of 21 correct diagnoses, better than had been achieved by any of the pathologists who had seen the same sections previously (17 of 21), and considerably better than the average proportion of correct diagnoses provided by all 37 renal transplant pathologists (65%). Application of the system by a second pathologist produced a tendency to overdiagnosis of acute rejection, illustrating the consequences of interobserver variation.

CONCLUSIONS

In the diagnosis of acute rejection, further useful information can be extracted from features that are currently not considered in the Banff classification. Integration of data by a computer can give a more reliable diagnosis of early acute rejection, but routine application will require the development of a more sophisticated system that can also accommodate clinical data, perhaps one that can continue to "learn" as more data are entered.

The use of digital images in pathology

Digital images are routinely used by the publishing industry, but most diagnostic pathologists are unfamiliar with the technology and its possibilities. This review aims to explain the basic principles of digital image acquisition, storage, manipulation and use, and the possibilities provided not only in research, but also in teaching and in routine diagnostic pathology. Images of natural objects are usually expressed digitally as 'bitmaps'--rectilinear arrays of small dots. The size of each dot can vary, but so can its information content in terms, for example, of colour, greyscale or opacity. Various file formats and compression algorithms are available. Video cameras connected to microscopes are familiar to most pathologists; video images can be converted directly to a digital form by a suitably equipped computer. Digital cameras and scanners are alternative acquisition tools of relevance to pathologists. Once acquired, a digital image can easily be subjected to the digital equivalent of any conventional darkroom manipulation and modern software allows much more flexibility, to such an extent that a new tool for scientific fraud has been created. For research, image enhancement and analysis is an increasingly powerful and affordable tool. Morphometric measurements are, after many predictions, at last beginning to be part of the toolkit of the diagnostic pathologist. In teaching, the potential to create dramatic yet informative presentations is demonstrated daily by the publishing industry; such methods are readily applicable to the classroom. The combination of digital images and the Internet raises many possibilities; for example, instead of seeking one expert diagnostic opinion, one could simultaneously seek the opinion of many, all around the globe. It is inevitable that in the coming years the use of digital images will spread from the laboratory to the medical curriculum and to the whole of diagnostic pathology.

A quantitative immunofluorescence study of glomerular cell adhesion proteins in proteinuric states

Whenever there is heavy proteinuria, the glomerular epithelial cells, the podocytes, show dramatic morphological changes which clearly demonstrate changes in cell adhesion. However, there is little information on the types of cell adhesion molecules expressed in the normal human glomerulus. Assessments of changes in cell adhesion molecules in human proteinuria have been confined to semi-quantitative immunostaining for integrins, and the results have not been entirely consistent. This study sought first to define which cell adhesion molecules are present in the normal glomerulus, using indirect immunofluorescence and a panel of antibodies directed against transmembrane adhesion proteins and against several cytoplasmic proteins which are known to be involved in adhesion. A wide variety of integrins were detected, the dominant form being alpha 3 beta 1. The cytoplasmic focal adhesion proteins vinculin, talin, paxillin, p130CAS, and pp125FAK were detected, although vinculin appeared to be confined mainly to the mesangium. The only intercellular adhesion molecule detected in the vicinity of the slit diaphragm was ZO-1; the results imply that the slit diaphragm does not bear a close relationship to any other form of intercellular junction. Changes in these adhesion components were also studied in proteinuria, using 18 cases each of minimal change nephropathy, 'early' membranous nephropathy, and normal controls. Fluorescence intensity was measured by image capture using a low light video camera and subsequent digital image analysis, an approach which demonstrated acceptable reproducibility. The most striking changes were an increase in phosphotyrosine and p130CAS in the nephrotic patients. Contrary to previous reports, little change was found in the expression of the most abundant integrins, nor did overall glomerular staining for ZO-1 alter. These results imply a controlled alteration in glomerular cell adhesion in nephrotic states in man, probable representing increased turnover of cell adhesion structures rather than the decrease which has been reported in short-term animal models. This is the first report of increased glomerular phosphotyrosine in man, which is associated with less stable adhesions and may be related to the loss of foot processes. Using human biopsy material, it was not possible to determine which proteins were phosphorylated, but the probable relationships to changes in cytoskeletal structure and slit diaphragm permeability justify further study.