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Objective: To determine whether optimized glycemic control in type I diabetic recipients of renal allografts will prevent or delay diabetic renal lesions in the allograft.Design: Prospective, controlled, and randomized trial of glycemic control in an inception cohort of type I diabetic renal allograft recipients. The experimental group underwent maximized glycemic control, and the standard group was treated in the same way as other patients in the transplant clinic. Patients underwent baseline (before transplant) and 5-year posttransplant allograft biopsies.Setting: University of Minnesota Hospital and Clinic and the Clinical Research Center and Hennepin County Medical Center, Minneapolis.Patients: Type I diabetics with terminal diabetic renal failure undergoing renal transplantation. Forty-eight patients randomized to maximized or standard control completed the trial.Intervention: Subcutaneous insulin given several times a day or continuously (maximized group) and once or twice each day (standard group) was used throughout the trial. A significant difference for hemoglobin A1 level was maintained (mean +/- SD: standard, 0.117 +/- 0.013; maximized, 0.096 +/- 0.016; P < 0.001).Main Outcome: The primary end point of this trial was the difference between the groups in renal glomerular mesangial expansion as determined by electron microscopy.Results: There was a more than twofold increase in the volume fraction of mesangial matrix per glomerulus in the standard group (mean +/- SD, 0.043 +/- 0.034) compared with the maximized group (0.019 +/- 0.038; P = .024). The threefold increase in arteriolar hyalinosis, the greater widening of the glomerular basement membrane, and increase of volume fraction of the total mesangium in the patients who received standard treatment all approached significance (P = .10 or less). The incidence of severe hypoglycemic episodes was greater in the maximized group (1.7 per patient per year) than in the standard treatment group (< 0.1 per patient per year; P < .001).Conclusions: This trial indicates a causal relationship between hyperglycemia and an important lesion of diabetic nephropathy, mesangial matrix expansion, in renal allografts transplanted into diabetic recipients. In addition, the results with other lesions central to the development of diabetic nephropathy support the major conclusion. [ABSTRACT FROM AUTHOR]

Objective: To determine outcome in diabetic pancreas transplant recipients according to risk factors and the surgical techniques and immunosuppressive protocols that evolved during a 33-year period at a single institution., Summary Background Data: Insulin-dependent diabetes mellitus is associated with a high incidence of management problems and secondary complications. Clinical pancreas transplantation began at the University of Minnesota in 1966, initially with a high failure rate, but outcome improved in parallel with other organ transplants. The authors retrospectively analyzed the factors associated with the increased success rate of pancreas transplants., Methods: From December 16, 1966, to March 31, 2000, the authors performed 1,194 pancreas transplants (111 from living donors; 191 retransplants): 498 simultaneous pancreas-kidney (SPK) and 1 simultaneous pancreas-liver transplant; 404 pancreas after kidney (PAK) transplants; and 291 pancreas transplants alone (PTA). The analyses were divided into five eras: era 0, 1966 to 1973 (n = 14), historical; era 1, 1978 to 1986 (n = 148), transition to cyclosporine for immunosuppression, multiple duct management techniques, and only solitary (PAK and PTA) transplants; era 2, 1986 to 1994 (n = 461), all categories (SPK, PAK, and PTA), predominantly bladder drainage for graft duct management, and primarily triple therapy (cyclosporine, azathioprine, and prednisone) for maintenance immunosuppression; era 3, 1994 to 1998 (n = 286), tacrolimus and mycophenolate mofetil used; and era 4, 1998 to 2000 (n = 275), use of daclizumab for induction immunosuppression, primarily enteric drainage for SPK transplants, pretransplant immunosuppression in candidates awaiting PTA., Results: Patient and primary cadaver pancreas graft functional (insulin-independence) survival rates at 1 year by category and era were as follows: SPK, era 2 (n = 214) versus eras 3 and 4 combined (n = 212), 85% and 64% versus 92% and 79%, respectively; PAK, era 1 (n = 36) versus 2 (n = 61) versus 3 (n = 84) versus 4 (n = 92), 86% and 17%, 98% and 59%, 98% and 76%, and 98% and 81%, respectively; in PTA, era 1 (n = 36) versus 2 (n = 72) versus 3 (n = 30) versus 4 (n = 40), 77% and 31%, 99% and 50%, 90% and 67%, and 100% and 88%, respectively. In eras 3 and 4 combined for primary cadaver SPK transplants, pancreas graft survival rates were significantly higher with bladder drainage (n = 136) than enteric drainage (n = 70), 82% versus 74% at 1 year (P =.03). Increasing recipient age had an adverse effect on outcome only in SPK recipients. Vascular disease was common (in eras 3 and 4, 27% of SPK recipients had a pretransplant myocardial infarction and 40% had a coronary artery bypass); those with no vascular disease had significantly higher patient and graft survival rates in the SPK and PAK categories. Living donor segmental pancreas transplants were associated with higher technically successful graft survival rates in each era, predominately solitary (PAK and PTA) in eras 1 and 2 and SPK in eras 3 and 4. Diabetic secondary complications were ameliorated in some recipients, and quality of life studies showed significant gains after the transplant in all recipient categories., Conclusions: Patient and graft survival rates have significantly improved over time as surgical techniques and immunosuppressive protocols have evolved. Eventually, islet transplants will replace pancreas transplants for suitable candidates, but currently pancreas transplants can be applied and should be an option at all stages of diabetes. Early transplants are preferable for labile diabetes, but even patients with advanced complications can benefit.

Although chickenpox can cause severe morbidity and mortality in pediatric renal transplant recipients, published reports describing treatment of these patients are few, especially in the cyclosporine era. Sixty-nine episodes of chickenpox occurring in 66 patients were diagnosed in our transplant population between January 1984 and May 1996. Immunosuppression consisted of prednisone and azathioprine (30 cases); prednisone, azathioprine, and cyclosporine (38 cases); or prednisone alone (1 case). Azathioprine was temporarily discontinued in 66 of 68 cases. Cyclosporine was continued at the preexisting dose in 36 of 38 cases. Acyclovir was administered parenterally in 62 of 69 cases. Sixty-five of 66 patients survived. Cyclosporine use did not increase the incidence of severe disease (p > 0.1). Acute allograft rejection occurred in three patients and responded to prednisone. Chickenpox in children with renal transplants can be successfully treated with intravenous acyclovir and temporary withdrawal of azathioprine. Allograft rejection is uncommon with this approach. Patients receiving cyclosporine do not appear to experience increased morbidity or mortality with chickenpox.

Chronic rejection (CR) is the most common cause of graft loss beyond the 1st posttransplant year. The aim of this analysis was to identify the risk factors for the development of CR in pediatric renal transplant recipients. Between June 1984 and March 1994, 217 renal transplants were performed in children at our center. Immunosuppression included prednisone, azathioprine, cyclosporine (CsA), and prophylactic antibody. Using multivariate analysis, we studied the impact of the following variables on the development of biopsy-proven CR: age at transplant (< or = 5 years, > 5 years), gender, race, transplant number (primary, retransplant), donor source (cadaver, living donor), donor age (< 20 years, 20-49 years, > 49 years), number of ABDR mismatches (0, 1-2, 3-4, 5-6), number of DR mismatches (0, 1, 2), percentage peak panel reactive antibody (PRA) (< or = 50%, > 50%), percentage PRA at transplantation (< or = 50%, > 50%), dialysis pretransplant, preservation time > 24 h, acute tubular necrosis requiring dialysis, initial CsA dosage (< or = 5 mg/kg per day, > 5 mg/kg per day), CsA dosage at 1 year posttransplant (< or = 5 mg/kg per day, > 5 mg/kg per day), acute rejection (AR), number of AR episodes (ARE) (1, > 1), timing of AR (< or = 6 months, > 6 months), reversibility of AR (complete, partial), and infection [cytomegalovirus (CMV), non-CMV viral, bacterial]. Risk factors for the development of CR in pediatric renal transplant recipients were: AR (P < 0.0001, odds ratio 19.4), multiple ARE (> 1 vs. 1) (P < 0.0001, odds ratio 30.1), and high percentage peak PRA (> 50%) (P < 0.03, odds ratio 3.6).

The expression of mRNA and distribution of alpha 1(IV), alpha 3(IV) chains of type IV collagen, matrix metalloproteinase 2 (MMP-2), and tissue inhibitor of metalloproteinase 1 (TIMP-1) were examined in kidneys from streptozotocin-diabetic rats, 2.5 months after administration of the drug, an early time point when specific diabetic glomerular changes were still minimal. Ten age-matched Sprague-Dawley rats were assigned to control and diabetic groups. Compared to the controls, the diabetic rats had a significantly lower body weight, higher kidney weight and serum glucose levels, but no significant changes of glomerular surface area and urine albumin were observed. Northern blot analysis, using whole kidney mRNA, revealed that diabetic rat kidneys expressed 113.5% more alpha 1(IV), 46.5% more alpha 3(IV), 54.8% less MMP-2 and 246% more TIMP-1 (in all instances: p < 0.05). These results were corroborated by in situ hybridization for RNA expression. A quantitative analysis of the data indicated the following changes in glomeruli: (1) 74.6% more alpha 1(IV), (2) 103.8% more alpha 3(IV), (3) 40.7% less MMP-2 and (4) 80.9% more TIMP-1. Similar changes were observed in tubular (proximal and distal) cells. We conclude that an increased synthesis and decreased degradation of renal extracellular matrix components occur early after induction of experimental diabetes, before the onset of typical structural changes in the kidneys, and represent changes of specific gene expression at the transcriptional level. All the cell types in the glomerulus as well as the proximal and distal tubules appear to be involved in this alteration of expression, and this is a novel finding.

We studied the impact of early cyclosporine (CSA) levels on the incidence of rejection in pediatric transplant recipients. Between 1 January 1984 and 31 December 1994, a total of 234 pediatric patients underwent kidney transplants and received CSA immunosuppression. We analyzed the impact of CSA levels (at 1 wk, 2 wk, 1 month, 2 months, and 3 months) on the incidence of rejection in the first 3 and the first 6 months post-transplant. We found that CSA levels at all timepoints correlated, i.e. recipients with low levels in the early post-transplant period tended to have low levels throughout the first 12 months. Multivariate analysis for risk factors by biopsy-proven rejection in the first 3 months revealed that the CSA trough level was the critical factor (p < 0.05). Recipients with CSA trough levels < 100 ng/ml had 2.24 times the risk of rejections vs. those with blood levels > 100 ng/ml. Similarly, the CSA trough level at 1 month was the critical risk factor for biopsy-proven rejection within the first 6 months (p < 0.05). The major risk factor for graft loss within the first 12 months was a biopsy-proven rejection episode. We conclude that in pediatric kidney transplant recipients, early CSA trough levels < 100 ng/ml are associated with a significantly increased incidence of rejection in the first 6 months post-transplant.

Infants are thought to be more immunoreactive and at a greater risk for developing irreversible rejection compared with older children. We investigated this by analyzing patient and graft survival rates, incidence of acute rejection, reversibility of acute rejection, development of a subsequent acute rejection, and incidence of graft loss due to rejection in 154 children (< 18 years of age) after primary renal transplantation. Most patients (n = 139) were treated with quadruple immunosuppression (antibody, azathioprine, prednisone, cyclosporine). Treatment of the first acute rejection episode (ARE) consisted of antibody and increased prednisone (68%) or increased prednisone alone (30%), and was not significantly different between the age groups. Transplants were from living donors (LRD) in 80% of cases. Patients were followed for at least 1 year (mean 58 +/- 30 months); 68% (105/154) of recipients experienced 1 or more ARE. The incidence of ARE was significantly lower in patients < 2 years of age (45%) compared with patients 2-5 (76%, P = 0.01), 6-12 (78%, P = 0.005), and 13-17 (76%, P = 0.009) years of age. There was no significant difference in the 1-, 2- and 5-year patient or graft survival rates, the development of a subsequent acute rejection, or the incidence of graft loss due to acute rejection when analyzed by age group. These data suggest that the impact of an ARE is similar for younger and older children in our population receiving predominantly LRD transplants and quadruple immuno-suppression.

At the University of Minnesota, outcome of renal transplants for infants and young children is the same as outcome for older children and adults. We reviewed our decision-making process in the pre-, peri-, and postoperative care of these recipients.

Between May 1, 1986 and May 31, 1992 at the University of Minnesota, we interpreted 129 renal allograft biopsy specimens (done in 48 grafts during the first 6 months posttransplant) as showing changes consistent with chronic rejection. For this retrospective analysis, we reexamined these biopsies together with clinical information to determine: (a) whether a diagnosis other than chronic rejection would have been more appropriate, (b) how early posttransplant any chronic rejection changes occurred, and (c) if the diagnosis correlated with outcome. We found that (1) chronic rejection is uncommon in the first 6 months posttransplant; it was documented in only 27 (2.4%) of 1117 renal allografts and was preceded by acute rejection in all but 3 recipients (for these 3, the first biopsy specimen showed both acute and chronic rejection). (2) Chronic vascular rejection was seen in 1 recipient as early as 1 month posttransplant; the incidence increased over time and was associated with an actual graft survival rate of only 35%. (3) The most frequent cause of arterial intimal fibrosis in the first 6 months posttransplant was arteriosclerotic nephrosclerosis (ASNS) of donor origin. Long-term graft function for recipients with ASNS was 67%. (4) Early-onset ischemia or thrombosis was seen in 14 recipients and predicted poor outcome: only 35.7% of these recipients had long-term graft function. (5) Cyclosporine (CsA) toxicity was implicated in only 3 recipients, who had mild diffuse interstitial fibrosis in association with elevated CsA levels. Other variables (including systemic hypertension, urinary tract infection, obstructive uropathy, neurogenic bladder, cobalt therapy, and recurrent disease) were not significantly associated with chronic renal lesions in the first 6 months posttransplant. A significant number of biopsies were originally interpreted as showing chronic rejection, but the diagnosis was changed upon reevaluation in conjunction with clinical data. We conclude that many factors coexist to produce chronic lesions in biopsies during the first 6 months posttransplant, so clinical correlation is needed before establishing a diagnosis of chronic rejection.

Acute renal insufficiency in the setting of hemolysis and thrombocytopenia, a triad that constitutes adult or pediatric hemolytic uremic syndrome, can be associated with or triggered by diverse conditions such as verocytotoxin-producing Escherichia coli, viral infections, pregnancy, malignant hypertension, scleroderma, renal radiation, allograft rejection, lupus erythematosus, and assorted medications such as mitomycin C, cyclosporine, and oral contraceptives. Recurrent and de novo hemolytic uremic syndrome occur after renal transplantation. Relapses are also common and probably reflect incomplete resolution of the initial episode. The major differential diagnoses of hemolytic uremic syndrome in the renal allograft include acute vascular rejection, cyclosporine, FK506 or antilymphocyte antibody nephrotoxicity, and malignant hypertension, all of which may display overlapping clinical and histologic features with primary hemolytic uremic syndrome; in such instances, the exact diagnosis may be quite difficult. It is possible that the risk of recurrence may be reduced by proper timing of transplantation and suitable choice of immunosuppressive agents. Intensive plasmapheresis in conjunction with fresh frozen plasma and supportive management of renal failure may lessen mortality and morbidity even in recurrent hemolytic uremic syndrome after transplantation.

We have previously characterized the evolution of renal cortical interstitial fibrosis in the rabbit model of unilateral ureteral obstruction (UUO). In our earlier report, we examined the extracellular matrix protein composition of the interstitial space. Of note, UUO was associated with the acquisition of prominent interstitial collagen IV immunoreactivity. Interstitial collagens I and III were also increased. In situ hybridization localized increased expression of collagens I and IV to cells of the interstitial space. In the current study, we examine metalloproteinase and metalloproteinase inhibitor expression in the obstructed renal cortex. Matrix metalloproteinase-2 is a metalloproteinase with activity against both collagen IV and denatured collagen I. At day 3 of UUO, both transcripts were significantly increased, although expression of these mRNAs was not different from controls after 7 and 16 days of UUO. Expression of mRNA of tissue inhibitor of the metalloproteinases (TIMP) was significantly increased in the UUO samples at all times, although it was maximal at day 3. Immunohistochemically, increased TIMP reactivity localized to the interstitial space, and TIMP mRNA expression was seen to parallel the interstitial macrophage infiltration that accompanies ureteteral obstruction. In contrast, TIMP-2 mRNA expression appeared to be biphasic, with peaks at both day 3 and day 16 of UUO. At day 7, expression was not different from controls. These data suggest a role for impaired matrix degradation in the development of interstitial fibrosis in the obstructed kidney, particularly at late times when collagen mRNA expression has returned to control values.

Renal morphometric analysis was performed in 15 (13 male) Alport syndrome patients ages 4 to 26 years, along with 10 controls ages 3 to 26 years, to better understand the structural basis of renal dysfunction in Alport syndrome. The glomerular basement membrane (GBM) width class frequencies of controls were normally distributed; those of Alport syndrome patients were slightly skewed, especially toward thicker classes, although there was also an increase in the proportion of thinner classes. Mesangial volume fraction was not different between Alport syndrome patients (0.21 +/- 0.09) and controls (0.19 +/- 0.04). There was an inverse correlation between mesangial volume fraction and creatinine clearance in Alport syndrome patients (r = -0.72, P < 0.01); however, the creatinine clearances in Alport syndrome patients were far less than in insulin-dependent diabetic patients with similar mesangial volume fraction. Similarly, there was no significant difference in the surface density of the peripheral GBM (in square micrometers per cubic micrometer) in Alport syndrome patients (0.12 +/- 0.04) versus controls (0.13 +/- 0.02). The surface density of the peripheral GBM correlated with creatinine clearance in Alport syndrome patients (r = 0.71, P < 0.01). However, there was a greater reduction in creatinine clearance as related to declining the surface density of the peripheral GBM in Alport syndrome than in diabetic patients. The cortical interstitial volume fraction was highly inversely correlated with creatinine clearance in Alport syndrome patients (r = -0.85, P < 0.01). Global glomerular sclerosis was 0% in five and 5 to 61% in nine Alport syndrome patients and correlated inversely with creatinine clearance (r = -0.74, P < 0.01). However, the creatinine clearance was lower in Alport syndrome than in diabetic patients with similar cortical interstitial volume fraction and percent glomerular sclerosis. There was no significant difference in an index of glomerular number between Alport syndrome patients and controls. Thus, changes in mesangial volume fraction, cortical interstitial volume fraction, percent glomerular sclerosis, and surface density of the peripheral GBM in Alport syndrome patients only partially account for the reduction in creatinine clearance. It was speculated that decreased glomerular capillary wall hydraulic conductivity in Alport syndrome could explain many of these observations.

Thickening of the glomerular basement membrane (GBM) and expansion of the mesangial matrix are hallmarks of human diabetic nephropathy. Renal tissues from 15 patients with type II (non-insulin-dependent) diabetes (NIDDM) were studied by immunofluorescence (IF) and immunogold electron microscopy (IEM) for the distribution of 2 type IV collagen peptides [alpha 3(IV) noncollagenous (NC) domain and alpha 4(IV) NC domain] and 2 classical type IV collagen chains [alpha 1(IV) NC domain and alpha 2(IV) domain]. There was intense staining for alpha 3(IV) NC and alpha 4(IV) NC domain in the GBM but not in the mesangial matrix of patients with overt diabetic nephropathy. In contrast, staining with antibodies to alpha 1(IV) NC and alpha 2(IV) NC domain reacted with mesangial matrix but was significantly decreased in the GBM in the patients with overt diabetic nephropathy. IEM confirmed the IF findings. These data suggest that expansion of the mesangial matrix and thickening of GBM in NIDDM involves separate and distinct type IV collagen components and that the site-specific matrix alterations in NIDDM and type I (insulin-dependent) diabetes are parallel.

In the past researchers have used an estimate of one million as the number of glomeruli in each human kidney. However, recent work on excised kidneys has demonstrated a large variation in glomerular number from one person to another (330,000 to 1,400,000) per kidney. Theoretically an in situ estimate of glomerular number could be obtained if renal cortical volume, volume density of glomeruli per cortex [Vv(glom/cortex)] and mean glomerular volume are known. We used a dog model to demonstrate that an accurate estimate of cortical volume could be obtained in situ using magnetic resonance imaging (MRI). Vv(glom/cortex) and mean glomerular volume were obtained from needle biopsies. An independent and more direct method (the fractionator) was used to validate the estimate of glomerular number obtained using MRI and renal biopsy. On average there was very good agreement between the fractionator method (379,000 +/- 40,000) and the MRI/renal biopsy method (376,000 +/- 108,000) for the 10 dog kidneys measured; however we found up to a 36% difference between the two methods in an individual kidney. Nonetheless, the estimate from the MRI/renal biopsy method has more precision than the assumption that there are one million glomeruli per human kidney.

We performed 73 kidney transplants in 51 patients with steroid-resistant nephrotic syndrome (SRNS) with focal segmental glomerular sclerosis (FSG) ages 18.4 +/- 12.8 (mean +/- SD) years. Recurrence of SRNS, defined by rapid onset of proteinuria, hypoalbuminemia and/or > 95% epithelial cell foot process effacement with or without the presence of FSG, occurred in 26 grafts in 16 patients. Acute renal failure (ARF) occurred in 16 of 26 (61.5%) grafts with recurrence versus 7 of 47 (14.9%) grafts without recurrence (P < 0.0001). ARF occurred in 4 of 9 (44.4%) living-related donor (LRD) recipients with recurrence and 3 of 21 (12.5%) LRD recipients without recurrence (NS). ARF in cadaver donor (CAD) recipients with recurrence was 12 of 17 (70.5%) versus 4 of 23 (17.4%) without recurrence (P < 0.0001). ARF was also higher in LRD or CAD with recurrence than in a control group of non-SRNS patients matched for age, sex and time of transplantation. Graft survival at one year was lower in patients with recurrence and ARF [4 of 16 (25%)] compared to patients with recurrence and no ARF [9 of 11 (82%), P < 0.01]. There was no difference in graft survival in patients without recurrence who did or did not have ARF. One or more acute rejection episodes occurred in all 16 patients with ARF and recurrence, in all 7 patients with ARF without recurrence, and in 7 of 10 patients with recurrence without ARF compared with only 11 of 40 (28%) of patients with neither recurrence nor ARF (P < 0.0001, < 0.001 and < 0.04, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

We have reviewed the clinical course of 30 pediatric bone marrow transplant (BMT) recipients requiring dialysis for acute renal failure early after BMT. Patients requiring dialysis were not significantly different from the general pediatric BMT population except for: (1) a greater proportion of neuroblastoma patients in the dialysis group, and (2) fewer autologous and more unrelated BMT donors in the dialysis group. Twenty-three patients (77%) died without recovering renal function 1-72 days (mean 12 days) after dialysis was begun. Sepsis was the most commonly cited cause of renal failure and death in these patients. Seven patients (23%) recovered sufficient renal function to stop dialysis; all long-term survivors were in this group. Factors at the onset of dialysis associated with persistent renal failure were weight gain of > or = 10% of baseline body weight, requirement of three or more drugs for blood pressure support and hyperbilirubinemia. Although acute renal failure requiring dialysis is an ominous development following BMT, recovery of renal function is possible with aggressive supportive care.

We used immunogold electron microscopic (IEM) techniques with periodate-lysine-paraformaldehyde-fixed and Lowicryl-embedded or cryopreserved tissues to study the distribution of alpha 1(IV) and alpha 3(IV) chains of Types IV and VI collagen in glomerular basement membrane (GBM) and mesangial matrix of glomeruli in normal human kidneys. Monoclonal antibodies to alpha 1(IV) and alpha 3(IV) collagen chains and Type VI collagen could be detected only with cryoultramicrotomy, whereas polyclonal anti-Type IV collagen antibody was detectable in Lowicryl-embedded tissue. Ultrastructural detail was better preserved in the Lowicryl-embedded tissue. IEM labeling provided more detailed information as to the site-specific array of these extracellular matrix molecules in glomeruli than did immunofluorescent microscopy. The labeling of alpha 1(IV) collagen chain was distributed mainly along the endothelial side of glomerular basement membrane and the mesangial matrix. Mesangial GBM was relatively poorly labeled compared with that of mesangial matrix. In contrast, the alpha 3(IV) chain was detected throughout the thickness of the GBM, but there was no labeling of mesangial matrix. Type VI collagen distribution was identical to that of the alpha 1(IV) chain within the glomerulus but was also associated with interstitial collagen fibrils. This study documents and details the heterogeneous distribution of Type IV and VI collagen chains within the normal human glomerulus and provides the framework for the study of these matrix components in human glomerular diseases.

We studied renal autoregulation in nondiabetic and streptozotocin diabetic Münich-Wistar rats 6 weeks after diabetes induction. We had previously shown that diabetic rats had greater preservation of renal blood flow (RBF) at reduced renal perfusion pressures (RPP) than control rats and speculated that this could be due to higher protein intake in the diabetic rats. Because of hyperphagia, the diabetic rats in the present study on a 24% protein diet (D-24) had 70% or greater increase in dietary protein intake compared to controls on the same diet (C-24). Diabetic rats on a 14% protein diet (D-14) had a dietary protein intake similar to C-24 and less than that of D-24 animals. Baseline glomerular filtration rate (GFR) and renal blood flow were lower and renal vascular resistance (RVR) was higher in the D-14 compared to the C-24 or D-24 rats. Nonetheless, at markedly reduced RPP both diabetic groups had better sustained RBFs and lower RVRs than the controls. Thus, increased dietary protein intake cannot explain the autoregulatory abnormalities in diabetes. Bilateral carotid artery ligation increased systemic blood pressure similarly in the C-24, D-24, and D-14 rats. All three groups responded with increased RVR to carotid artery ligation. Following carotid artery ligation, differences were no longer seen between diabetic and control rats for RBF at reduced RPPs. These studies indicate that diabetic rats are capable of generating increased RVR, ruling out impaired vascular constrictive capacity as an explanation of these hemodynamic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Current knowledge regarding the concordance and discordance of the eye and kidney complications of diabetes is based on observations by ophthalmoscopy of retinal structural changes, which may be present at early stages of the disorder, and renal functional changes, which only become apparent at the later stages of the disease. For this reason we investigated the relationship between retinal structural lesions and quantitative measures of glomerular structure in patients with insulin-dependent diabetes mellitus (IDDM). Renal biopsies were evaluated using morphometric techniques, and retinopathy classification was determined by retinal fundus photography in 86 patients with IDDM: age 30.4 +/- 7.3 years and duration of IDDM 18.9 +/- 6.3 years (mean +/- SD). Retinopathy score correlated with glomerular basement membrane width (r = 0.39, P = 0.0002), mesangial volume fraction (VvMes/Glom) (r = 0.35, P = 0.0009), surface density of the peripheral capillary wall (SvPGBM/Glom) (r = 0.34, P = 0.0013), and index of arteriolar hyalinosis (r = 0.36, P = 0.0008). Abnormalities in VvMes/Glom and SvPGBM/Glom were more pronounced in patients with both retinopathy and hypertension. Four of the 15 patients (27%) with either normal urinary albumin excretion (UAE) or low-level microalbuminuria had advanced retinopathy but normal VvMes/Glom. In conclusion, the presence of advanced retinal disease with or without hypertension in patients with IDDM indicates a greater likelihood of advanced nephropathy as evidenced by increased VvMes/Glom and decreased SvPGBM/Glom. However, marked discordance between retinopathy and nephropathy occurs, as illustrated by patients with normal UAE or low-level microalbuminuria, normal glomerular structural measures, and advanced retinopathy.

We examined type IV collagen distribution and density in human diabetic kidneys by quantitative immunogold electron microscopy. We studied normal kidney transplant donors and "slow-track" and "fast-track" insulin dependent diabetic (IDDM) patients. The "slow-track" patients had IDDM for > or = 20 years and mesangial volume fraction (VvMes/glom) of < or = 0.32. The "fast-track" patients had IDDM for < or = 20 years and VvMes/glom > or = 0.37. Renal biopsies were embedded in Lowicryl, reacted with polyclonal anti-type IV collagen (in the distribution of the classical alpha 1(IV) and alpha 2(IV) collagen chains) and monoclonal anti-alpha 4(IV) collagen chain antibody followed by gold conjugated secondary antibody. We found, by morphometric techniques, a decrease in the immunogold densities of anti-type IV collagen in the subendothelial zone of the GBM in the "fast-track" IDDM patients. There was a trend towards a decrease in mesangial matrix (MM) particle density in the "fast-track" (P = 0.07) but not in the "slow-track" patients. However, because of the marked increase in MM in the "fast-track" patients, the per glomerulus estimated quantity of these antigens in MM was increased. In contrast, the density of alpha 4(IV) collagen chain was increased in the epithelial zone of the GBM in the "fast-track" IDDM patients. It is not known whether these changes in glomerular type IV collagen represent markers of advanced diabetic lesions or whether these changes might be detected earlier in diabetic patients destined for the later development of serious lesions.

At our institution, 521 kidney transplants were performed in 429 children (mean age 8.7 +/- 5.6-years) between 1969 and 1991. Of these transplants, 408 were primary, 113 were retransplants, 347 were living related, 171 were cadaver, and 3 were living nonrelated. Immunosuppression consisted of prednisone, azathioprine, and Minnesota antilymphocyte globulin (non-CSA) in 339 patients, total lymphoid irradiation in 8, and, more recently, cyclosporine (CSA) in addition in 168 patients. Average follow-up was 8.8 +/- 6.0 years. Actuarial graft survival in the non-CSA versus CSA groups at 1 year was 77.0% versus 85.7%; at 5 years, 59.6% versus 71.9%. Of 136 non-CSA patients, causes of graft loss at 5 years included: chronic rejection in 55 (40.4%), acute rejection in 27 (19.9%), recurrent disease in 16 (11.8%), technical complications in 8 (5.9%), infectious complications in 4 (2.9%), other causes in 5 (3.7%), and death with a functioning graft in 21 (15.4%). Of 40 CSA patients, causes of graft loss at 5 years included: chronic rejection in 16 (40.0%), acute rejection in 8 (20.0%), recurrent disease in 6 (15.0%), technical complications in 3 (7.5%), other causes in 2 (5.0%), and death with a functioning graft in 5 (12.5%). The causes of graft loss did not significantly differ in the non-CSA and CSA groups. Chronic rejection was the most common cause of graft loss in both groups. Research focusing on chronic rejection is needed to improve graft outcome in pediatric kidney transplantation.

Although 4000 pancreas transplants have now been done, alone or in combination with a kidney transplant, the risk/benefit profile of the procedure has not been established by controlled studies. A solo pancreas transplant abolishes the need for daily insulin but requires chronic immunosuppression, has high failure rates, and is not proved to lessen the chronic complications of diabetes. Thus, it is probably justified only in those diabetic patients with incapacitating disease. For uraemic diabetic patients, combined pancreas and kidney transplantation often removes dependence on both insulin and dialysis, and has lower rejection rates than pancreas transplant alone. However, it needs more immunosuppression than kidney transplant alone, has no proven benefit on chronic complications of diabetes, and carries an increased risk of rejection, infection, and cancer. Living-related-donor kidney transplantation followed by cadaver pancreas transplantation is a possible alternative. Transplantation of pancreatic islets could offer the advantages of strict metabolic control without the drawbacks of immunosuppressive therapy. Thus, research efforts should concentrate on immune-protected islet transplantation. An alternative approach to avoiding long-term immunosuppression is the promotion of allograft tolerance.

Diabetic rats manifest abnormal renal hemodynamic responses, with persistent renal vasodilation at reduced renal perfusion pressures. We hypothesized that in diabetes, renal hemodynamics are modulated by increased activity of the endogenous vasodilator, NO. In anesthetized Munich-Wistar rats, after 6 wk of streptozotocin-induced, insulin-treated diabetes, and in age-matched, nondiabetic littermates (n = 7-8), basal renal hemodynamics and responses to graded reductions in renal perfusion pressure were determined before and after intrarenal arterial infusion of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). An identical protocol was followed in a second cohort of rats pretreated with indomethacin (4 mg/kg iv). Diabetic rats demonstrated hyperglycemia, renal enlargement, hyperfiltration, and increased urinary excretion of the stable NO metabolites, NO2 and NO3. L-NAME eliminated basal hyperfiltration in diabetic rats, and L-NAME, but not indomethacin, also eliminated persistent renal vasodilation at reduced renal perfusion pressure. We conclude that in a rat model of diabetes, increased endogenous NO activity may play a role in basal hyperfiltration and in the persistent renal vasodilatation manifested at reduced renal perfusion pressures.

Pancreas transplantation prevents or retards development of early diabetic glomerular lesions in renal allografts transplanted to patients with insulin-dependent diabetes mellitus (IDDM), but its effect on established renal lesions in native kidneys of such patients is unknown. Renal biopsy samples were taken before and 5 years after pancreas transplantation from 13 non-uraemic IDDM patients and compared with baseline and 5-year biopsy samples from 10 persistently hyperglycaemic IDDM patients who did not undergo transplantation. The two groups were similar in age, duration of diabetes, metabolic control, renal function, and blood pressure. Glomerular structures were measured by standard morphometric techniques. Haemoglobin A1 concentrations fell to within the normal range after pancreas transplantation but did not change in the comparison group. Glomerular basement membrane width did not significantly change in either group. Glomerular volume decreased and mesangial fractional volume increased in the pancreas transplant recipients but there was no significant change in total mesangial volume over 5 years. By contrast, both glomerular volume and mesangial fractional volume increased in the comparison patients, resulting in increased total mesangial volume. Diabetic glomerular lesions in patients with their own kidneys were not ameliorated by pancreas transplantation, despite 5 years of normoglycaemia. Pancreas transplantation can correct severe metabolic instability and thus improve quality of life, but it cannot yet be recommended for the treatment of established lesions of diabetic nephropathy.

Interstitial fibrosis and tubular basement membrane (TBM) thickening are evident within 16 days of unilateral ureteral obstruction (UUO) in the rabbit, and resemble the changes previously reported in hydronephrotic human kidneys. The cortical interstitial volume fraction in this rabbit model at 16 days is 43.3 +/- 6.1% (+/- 1 SD) in UUO kidneys, 4.9 +/- 3.1% in contralateral kidneys (CLK), and 2.8 +/- 0.8% in kidneys from sham-operated animals (ANOVA, P < 0.0001). Immunohistochemically, UUO is associated with increased interstitial collagens I and III, fibronectin, heparan sulfate proteoglycan and tubulointerstitial nephritis antigen. Aberrant collagen expression is also evident as interstitial collagen IV becomes prominent. Focal, peritubular accumulation of collagens I and II also appear to encircle the TBM. These changes are accompanied by an early, transient increase in renal cortical mRNA encoding the alpha 1 monomers of collagens I, III and IV, implicating increased matrix synthesis in the pathogenesis of obstructive nephropathy. In situ hybridization localized increased expression of alpha 1 (I) and alpha 1 (IV) mRNA to cells in the interstitial space, with clusters of alpha 1(I) positive cells associated with dilated tubules, muscular arteries and the periglomerular interstitium.

Primary hyperoxaluria type 1 (PH1) is a rare autosomal recessive disease caused by a deficiency of the liver-specific peroxisomal enzyme alanine:glyoxylate aminotransferase (AGT). Three unrelated PH1 patients, who possess a novel complex phenotype, are described. At the enzymological level, this phenotype is characterized by a complete, or nearly complete, absence of AGT catalytic activity and reduced AGT immunoreactivity. Unlike normal individuals in whom the AGT is confined to the peroxisomal matrix, the immunoreactive AGT in these three patients was distributed approximately equally between the peroxisomes and mitochondria. The peroxisomal AGT appeared to be aggregated into amorphous core-like structures in which no other peroxisomal enzymes could be identified. Mutational analysis of the AGT gene showed that two of the three patients were compound heterozygotes for two previously unrecognized point mutations which caused Gly41-->Arg and Phe152-->Iso amino acid substitutions. The third patient was shown to be a compound heterozygote for the Gly41-->Arg mutation and a previously recognized Gly170-->Arg mutation. All three patients were homozygous for the Pro11-->Leu polymorphism that had been found previously with a high allelic frequency in normal populations. It is suggested that the Phe152-->Iso and Gly170-->Arg substitutions, which are only eighteen residues apart and located in the same highly conserved internal region of 58 amino acids, might be involved in the inhibition of peroxisomal targeting and/or import of AGT and, in combination with the Pro11-->Leu polymorphism, be responsible for its aberrant mitochondrial compartmentalization. On the other hand, the Gly41-->Arg substitution, either in combination with the Pro11-->Leu polymorphism or by itself, is predicted to be responsible for the intraperoxisomal aggregation of the AGT protein.

Eighty-four patients with insulin-dependent diabetes mellitus had studies of renal function and quantitative renal morphometry including mesangial volume fraction (Vvmes/glom), index of arteriolar hyalinosis, percentage of globally sclerosed glomeruli (%GS), and interstitial volume fraction for total renal cortex (Vvint/T). There was significant correlation among these four parameters, and all four structural parameters correlated with glomerular filtration rate and the log of urinary albumin excretion. Stepwise multiple regression analysis showed that Vvmes/glom and Vvint/T were additive, suggesting that they are partially independent. Arteriolar hyalinosis and %GS did not improve the correlations further. We hypothesize that Vvmes/glom, Vvint/T, arteriolar hyalinosis, and %GS represent multiple but probably interrelated pathologic mechanisms leading to the functional disturbances of diabetic nephropathy. Longitudinal studies of patients with diabetes and studies of patients with diseases producing interstitial expansion in the absence of glomerular disease may help clarify the independent role of interstitial expansion in the kidney disease of diabetes mellitus.

We quantitated glomerular and cortical interstitial structures in nine type I mesangiocapillary glomerulonephritis (MCGN) patients aged 6 to 20 years whose creatinine clearance (CCr) was 10 to 129 ml/min/1.73 m,2 as compared to age-matched normal controls. Mean glomerular volume and mesangial volume fraction [Vv(mes/glom)] were increased and the percentage of the capillary endothelial circumference which was defined as filtration surface was decreased in type I MCGN patients. Vv(mes/glom) was inversely related to filtration surface area per glomerulus (r = -0.73, P < 0.05) and directly to volume density of cortical interstitium [Vv(int/cortex)] (r = +0.90; P < 0.01). Vv(mes/glom) (r = -0.87; P < 0.01), filtration surface area per glomerulus (r = +0.83; P < 0.01) and Vv(int/cortex) (r = -0.86; P < 0.01) were correlated with CCr. Thus, in type I MCGN, measures both of glomerular and of cortical interstitial structure are highly correlated with glomerular function.

We evaluated hepatic alanine glyoxylate aminotransferase (AGT) activity in percutaneous hepatic biopsy material obtained from four children with long-term renal allograft function following transplantation for primary hyperoxaluria type 1 (PH 1). The study was performed to determine whether these successes had occurred because relatively high residual levels of AGT activity had introduced a selection bias. The children ranged from seven months to eight years at transplant and are currently well 7 to 11 years later, with no oxalate deposition on repeated allograft biopsies and creatinine clearances of 80 to 128 ml/min/1.73 m2. AGT activity ranged from 0 to 13.8%, and in two of three patients with detectable levels the AGT was in mitochondria rather than peroxisomes. These results indicate that long-term renal allograft success can occur in spite of severe AGT deficiency. Thus, the therapeutic choice of kidney alone versus combined kidney-liver transplant cannot currently be made by measuring residual hepatic AGT in PH 1. Kidney transplant alone remains a reasonable initial therapeutic alternative for patients with recent onset of renal insufficiency due to PH 1.

Clinical diabetic nephropathy in man is the consequence of the development of a specific constellation of glomerular, tubular, vascular, and interstitial structural abnormalities accompanied by highly characteristic immunohistochemical alterations that, together, are unique to diabetes. Because changes resembling the specific pathology of diabetes do not develop in patients with conditions that lead to long-standing glomerular hyperfunction (such as unilateral nephrectomy), it is unlikely that glomerular hemodynamic abnormalities per se can be the cause of diabetic nephropathy. Whether hemodynamic abnormalities represent a risk factor that, in the presence of the diabetic state, can accelerate the rate of development of the basic lesions of diabetic nephropathy is currently unclear. However, there is considerable evidence that when the renal lesions of diabetes are far advanced, factors such as systemic hypertension can determine the rate of renal functional deterioration in diabetes as in other disorders. Although the diabetic rat may be a useful model for the study of aspects of the pathogenesis of diabetic nephropathy, much confusion has resulted from the inclusion of focal segmental glomerular sclerosis as a diabetic lesion. Similarly, the acceptance of all increases in urinary protein excretions in this model as resulting from or reflecting of diabetic nephropathology can be misleading. It is concluded that treatment aimed at manipulating renal hemodynamics in diabetic patients without evidence of renal disease should remain in the realm of clinical research.

In a cross-sectional study, glomerular basement membrane (GBM) width, the volume fractions of the mesangium (VvMes), its cell (VvCell) and matrix (VvMatx) components, and surface density of the peripheral capillary surface (SvPGBM) were measured in renal biopsies from 187 nondiabetic living related and cadaveric donors of kidneys for transplantation and from 150 patients with insulin-dependent (type I) diabetes mellitus of 1-41 yr duration. In the diabetic patients, the matrix was the major factor in the expansion of the mesangium. However, both VvCell (0.11 +/- 0.04) and VvMatx (0.20 +/- 10) in diabetic patients exceeded the same measurements in nondiabetic subjects (0.07 +/- 0.02 for each component) (P less than 0.001 in each case). Linear regression analysis demonstrated significant correlations (P less than 0.001 for all) between GBM width, VvMes, VvCell, VvMatx, or SvPGBM and either urinary albumin excretion and creatinine clearance, with the higher correlation coefficients in all cases with albuminuria. Of the structural parameters, VvMatx correlated best with either functional measure by stepwise regression, with GBM as an added factor only with albuminuria. Therefore, although models of diabetic glomerulopathy must consider enlargement of both mesangial cells and matrix, the predominant factor in the progression of structural and functional renal disease is mesangial matrix expansion.

Eight women with insulin-dependent diabetes mellitus (IDDM) with low creatinine clearance rate (CCR) and normal urinary albumin excretion (UAE) were compared with three other groups of diabetic women: 19 with normal creatinine clearance rate (CCR) and UAE, 7 with normal CCR and microalbuminuria, and 7 with low CCR and microalbuminuria. The four groups were similar in age, duration of diabetes, HbA1, incidence of urinary tract infection, prevalence of bladder neuropathy, and urinary urea nitrogen excretion rate. The prevalence of hypertension was similar among the groups, although mean arterial pressure was higher in the low CCR and microalbuminuria group. Renal area index was lower in the low CCR and normal UAE groups than in the other groups of diabetic patients, but was not different from normal. Morphometric measures of mesangial expansion and estimates of arteriolar hyalinosis and global glomerulosclerosis were increased to a similar degree in the low CCR and normal UAE, normal CCR and microalbuminuria, and low CCR and microalbuminuria groups compared with the group without abnormalities of renal function. Therefore, it is likely that diabetic glomerulopathy is, at least in part, responsible for the loss of glomerular filtration rate seen in the low CCR and normal UAE patients. Thus, the definition of incipient nephropathy may have to be expanded beyond the concept of microalbuminuria if longitudinal study of such patients reveals an increased risk of the subsequent development of overt nephropathy. Finally, screening for diabetic kidney disease among IDDM patients should include determination of glomerular filtration rate and measurement of UAE and blood pressure, especially among women.

The natural history of focal segmental glomerulosclerosis in patients retransplanted after loss of a primary allograft is not well established. We studied 14 patients with FSGS who were retransplanted between April 1964 and September 1990 to determine if recurrence in a second or subsequent allograft could be predicted. In this group, 8 of the primary allografts were lost to recurrent disease and 6 to rejection. None of the 6 patients who lost their primary allograft to rejection without evidence of recurrent FSGS suffered recurrent disease after retransplantation. In contrast, 3 of the 8 patients who lost their primary allograft rapidly to FSGS suffered recurrent disease and loss of function in all subsequent allografts. The remaining 5 patients had prolonged function of the primary allograft ranging between 4 and 10.5 years, despite recurrence of FSGS. Of these 5 patients, 2 have excellent renal function after retransplantation without recurrence of FSGS in the secondary allograft at 9 and 10.5 years posttransplant; 2 have lost their secondary allograft to recurrent FSGS, but are free of recurrence in the third allograft at 0.5 and 5.8 years postoperatively; 1 maintains a serum creatinine level of 1.9 mg% despite recurrence of FSGS in the secondary allograft at 1 year postoperatively. Our data show that, without recurrence of FSGS in the primary allograft, further renal transplants will be free of recurrent disease. Based on this finding, we advocate use of living-related donors for second transplants in these patients. With rapid recurrence of FSGS and subsequent accelerated loss of the primary allograft, further renal transplants carry a high likelihood of recurrent FSGS and graft loss. A substantial proportion of patients with recurrent FSGS in the primary allograft will have prolonged renal function, and are likely to have excellent results with subsequent allografts.

Methods for estimating glomerular volume were compared in Zenker-fixed, paraffin-embedded biopsies from 10 patients with insulin-dependent diabetes mellitus and 6 normal kidney donors. Two methods of measurement of individual glomerular volumes were used: the Cavalieri method (considered the "gold standard") and the maximal profile area (MPA) method. Also studied were the method of Weibel and Gomez and a method based on the disector principle; both estimate mean volume (VG). MPA and Cavalieri showed strong correlation (r = 0.93; P less than 0.001), although the MPA method consistently overestimated the true volume; six glomeruli were necessary for a reliable estimate of VG. The disector method did not correlate with VG determined by Cavalieri. Weibel-Gomez did correlate with Cavalieri (r = 0.68; P less than 0.05), but overestimated VG. At least 15 profiles were needed to provide a dependable estimate of VG by Weibel-Gomez. The Cavalieri, MPA, and Weibel-Gomez methods all can provide reliable estimates of VG, the latter two with appropriate correction factors. The individual glomerular volume methods, while more time consuming, provide information on variation and distribution of the glomerular population and are the methods of choice for studies of glomerular volume.

Purpose: To review renal pathological changes in diabetes, which include thickening of all renal extracellular basement membranes and the mesangial matrix and, to a lesser extent, mesangial cell expansion., Critical Renal Lesions in Diabetic Nephropathy: Two renal lesions appear critical in diabetic nephropathy. Mesangial expansion out of proportion to the size of the glomerulus is inversely related to proteinuria, hypertension and a declining glomerular filtration rate. Arteriolar hyalinosis is related to global glomerulosclerosis and both are correlated with the clinical features of nephropathy. By the time renal dysfunction is clinically detectable, these lesions tend to be advanced. Interstitial volume may be increased in insulin-dependent diabetes mellitus, particularly in areas containing sclerotic glomeruli or marked tubular atrophy., Future Research: Longitudinal studies of renal structure and function and a simultaneous study of potential risk factors and pathways of injury are necessary to develop more refined predictors and clearer pathogenic concepts of this important diabetic complication.

Renal pathological changes of diabetes include thickening of all renal extracellular basement membranes and the mesangial matrix and, to a lesser extent, mesangial cell expansion. Two renal lesions appear critical in diabetic nephropathy. Mesangial expansion out of proportion to the size of the glomerulus is related to proteinuria, hypertension, and declining GFR. Arteriolar hyalinosis is related to global glomerulosclerosis, and both are correlated with the clinical features of nephropathy. By the time renal dysfunction is clinically detectable, these lesions tend to be advanced. Interstitial volume may be increased in insulin-dependent diabetes mellitus, particularly in areas containing sclerotic glomeruli or marked tubular atrophy. Parallel findings were documented for type I membranoproliferative glomerulonephritis in which the increased mesangial volume fraction was related to decreased GFR, increased glomerular permeability to protein, and hypertension. As in diabetes, the cortical interstitial volume fraction is correlated with functional abnormalities in type I membranoproliferative glomerulonephritis. Thus, in both of these chronic glomerular disorders, mesangial expansion and interstitial expansion are associated with disordered renal function. Thus, it is not true that glomerular structural changes correlate poorly with glomerular function. Whether it is the glomerular or interstitial pathology or both that is causally responsible for the dysfunction requires further study.

Although hypertension is an important complication of diabetes it is unclear whether its association with other diabetic complications represents cause or consequence. Our study is a cross sectional evaluation of the relationship of blood pressure to renal structural and functional parameters. In 139 patients with insulin dependent diabetes for 18.9 +/- 7.4 years (mean +/- SD), we divided the patients into those with markedly increased mesangial volume fraction [Vv(mes/glom) greater than or equal to 0.37] and those with less [Vv(mes/glom) less than 0.37]. Hypertension (systolic BP greater than or equal to 160 and/or diastolic BP greater than 90 mm Hg or receiving BP medications) occurred in 29/40 with Vv(mes/glom) greater than or equal to 0.37. All 40 had clinical nephropathy with urinary albumin excretion (UAE) greater than 200 mg/24 hr. By two-way ANOVA creatinine clearance was lower and albuminuria was increased with both hypertension and the expanded mesangium. Also other measures of renal structure including filtration surface, index of interstitial fibrosis and index of arteriolar hyalinosis were increased by hypertension and mesangial expansion. Most patients with hypertension had other criteria for clinical nephropathy. Since, in these studies, we could not determine if hypertension contributed to or resulted from the renal lesions, we developed an estimate of the rate of mesangial expansion. We found that patients with normal BP (119 +/- 11/78 +/- 7 mm Hg) can be rapidly developing mesangial expansion. These studies support the view that the development of serious renal lesions can be independent of hypertension in IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)

Heparan sulfate proteoglycans (HSPG) are negatively charged constituents of the renal extracellular matrix including the glomerular basement membrane (GBM) and mesangial matrix. Biochemical and functional studies of patients with type-1 insulin dependent diabetes mellitus (IDDM) suggest that alterations of HSPG may occur in diabetic nephropathy. We have utilized a specific cytochemical method and electron microscopy to quantitate the distribution of HSPG in the GBM of 10 normal people and in 16 IDDM patients with a spectrum of clinical and structural changes. Enzyme incubation studies of normal infant kidney demonstrated that heparitinase removed 94% of the stainable anionic sites in the lamina rara externa (LRE) and 77% of the sites in the lamina rara interna (LRI) of the GBM. In contrast, incubation in the enzyme chondroitinase ABC did not reduce the number of sites in the LRE but reduced the number of sites in the LRI by 26%. The HSPG anionic sites in normal subjects were distributed in the LRE as 20.9 +/- 1.3, and in the LRI as 13.1 +/- 2.2 per micron GBM length. Anionic sites were slightly reduced (19.6 +/- 1.3, P less than 0.04) in the LRE of IDDM patients with normal urinary albumin excretion rates (UAE), or microalbuminuria, and were reduced in both the LRE and LRI of IDDM patients with clinical proteinuria (13.1 +/- 2.3, P less than 0.001 and 8.9 +/- 2.1, P less than 0.001, respectively). The number of anionic sites in the LRE and LRI, respectively, correlated with UAE (r = +0.78, P less than 0.001, r = +0.58, P less than 0.02), with GBM thickness (LRE, r = +0.81, P less than 0.001; LRI, r = +0.67, P less than 0.01) and with the volume fraction of mesangium (LRE, r = +0.59, P less than 0.02; LRI, r = +0.58, P less than 0.03). These data confirm earlier biochemical findings of a reduction of HSPG in the GBM in advanced diabetic nephropathy but do not provide evidence for the loss of HSPG in the GBM as a mechanism for early microalbuminuria.

Two female siblings were treated for acute neonatal hyperammonaemia due to complete carbamyl phosphate synthetase I deficiency. The first child was detected clinically at 65 hours of age and therapy started at 79 hours. The second child was followed from birth and therapy started at 5 hours of age. The extrapolated rate of increase of blood ammonia, in the first hours of life before therapy started, was 19 mumol L-1 h-1 in both babies. Peak blood ammonia level was 2235 mumol/L in the first (clinically detected) child and 271 mumol/L in the second (prospectively followed) child. The second child became symptomatic at 3 hours of age when blood ammonia level was as low as 90 mumol/L, whereas blood ammonia levels above 100 mumol/L caused no symptoms during recovery. The child detected clinically required haemodialysis and peritoneal dialysis to treat the hyperammonaemia. In the prospectively treated child, early therapy with intravenous sodium benzoate and sodium phenylacetate slowed the rate of increase in blood ammonia level, but this therapy did not prevent the need for peritoneal dialysis.

Diabetic nephropathy, clinically defined by overt albuminuria, hypertension and declining GFR, affects 25-35% of IDDM patients. The risk of nephropathy peaks during the second decade of IDDM and declines thereafter, suggesting that only a subset of IDDM patients is at risk for nephropathy. A role for hypertension in the progression of established renal damage in IDDM is now accepted; however the role of hypertension in the genesis of diabetic nephropathy is not yet clear. Mesangial expansion is a characteristic lesion of diabetic nephropathology and correlates with renal function. Functional studies are not indicative of underlying renal pathology except relatively late, when glomerular injury is advanced. Microalbuminuria in the 'predictive' range (greater than 30 micrograms/min) and associated with hypertension and/or declining GFR is a marker of established diabetic glomerulopathy. Only carefully designed longitudinal studies of renal morphology and function with accurate blood pressure monitoring beginning early in the course of IDDM will clarify the relationships between blood pressure and renal damage in IDDM. In NIDDM the frequent presence of non-diabetic renal lesions, of hypertension at or before the onset of diabetes, and the relative paucity of clinical-pathological correlations currently make it difficult to understand the role of hypertension in the genesis and progression of nephropathy. Again, longitudinal studies of blood pressure and renal structure and function are required in NIDDM patients. Finally, animal models of hypertension and diabetes may aid progress in these areas.

Denys-Drash syndrome is a rare human condition in which severe urogenital aberrations result in renal failure, pseudohermaphroditism, and Wilms' tumor (nephroblastoma). To investigate its possible role, we have analyzed the coding exons of the Wilms' tumor suppressor gene (WT1) for germline mutations. In ten independent cases of Denys-Drash syndrome, point mutations in the zinc finger domains of one WT1 gene copy were found. Nine of these mutations are found within exon 9 (zinc finger III); the remaining mutation is in exon 8 (zinc finger II). These mutations directly affect DNA sequence recognition. In two families analyzed, the mutations were shown to arise de novo. Wilms' tumors from three individuals and one juvenile granulosa cell tumor demonstrate reduction to homozygosity for the mutated WT1 allele. Our results provide evidence of a direct role for WT1 in Denys-Drash syndrome and thus urogenital system development.

In examining the pathophysiology underlying the development of hypertension in diabetes mellitus, it is important to draw clear distinctions between Type I and Type II diabetes. In patients with Type I diabetes, with a peak onset of disease early in the second decade of life, hypertension clearly represents the sequelae to the development of substantial renal lesions, especially in the glomerulus. Thus the prevalence of hypertension in those patients without substantial glomerular lesions approximates the incidence of hypertension in the general population (approximately 4%). In patients with Type II diabetes mellitus and onset generally later in adult life, an increase in blood pressure can often be demonstrated early after or even before diagnosis of the disease (most readily demonstrated in the Pima Indians). Furthermore, clear familial tendencies towards the development of nephropathic complications of diabetes can be shown. In patients with Type I disease, the fall in glomerular filtration rate parallels the fall in glomerular capillary surface available for filtration. This reduction in the peripheral glomerular capillary surface correlates well with the expansion of the mesangium, strongly implicating the mesangial expansion in the demise in renal function. For both Type I and Type II diabetes mellitus, the increase in albuminuria may reflect an opening of large pores in the glomerular basement membrane, thereby allowing serum proteins to cross into the filtration space.