Quantifying intrinsic and extrinsic control of single-cell fates in cancer and stem/progenitor cell pedigrees with competing risks analysis.

The molecular control of cell fate and behaviour is a central theme in biology. Inherent heterogeneity within cell populations requires that control of cell fate is studied at the single-cell level. Time-lapse imaging and single-cell tracking are powerful technologies for acquiring cell lifetime data, allowing quantification of how cell-intrinsic and extrinsic factors control single-cell fates over time. However, cell lifetime data contain complex features. Competing cell fates, censoring, and the possible inter-dependence of competing fates, currently present challenges to modelling cell lifetime data. Thus far such features are largely ignored, resulting in loss of data and introducing a source of bias. Here we show that competing risks and concordance statistics, previously applied to clinical data and the study of genetic influences on life events in twins, respectively, can be used to quantify intrinsic and extrinsic control of single-cell fates. Using these statistics we demonstrate that 1) breast cancer cell fate after chemotherapy is dependent on p53 genotype; 2) granulocyte macrophage progenitors and their differentiated progeny have concordant fates; and 3) cytokines promote self-renewal of cardiac mesenchymal stem cells by symmetric divisions. Therefore, competing risks and concordance statistics provide a robust and unbiased approach for evaluating hypotheses at the single-cell level.

Differential expression of laminin isoforms in diabetic nephropathy and other renal diseases.

Laminin a non-collagenous glycoprotein is a major component of the renal glomerular basement membrane and mesangium. Thus far eleven distinct chains have been described, permutations of which make up 15 laminin isoforms. Laminin molecules interact with cells and other matrix molecules during organ development and differentiation. We studied the distribution of laminin isoforms in patients with type 1 diabetic nephropathy, membranous nephropathy, membranoproliferative glomerulonephritis and IgA nephropathy/ Henoch-Schönlein purpura. Immunofluorescence microscopic studies with laminin-chain-specific antibodies to the α1, α2, α5, ß1, ß2 and γ1 chains detected α2, ß1 and γ1 chain expression in the normal mesangium and α5, ß2 and γ1 in normal glomerular basement membrane. Significantly, constituents of the glomerular basement membrane, α5, ß2 and γ1 chains were overexpressed in kidneys with diabetic nephropathy. Initially the constituents of the mesangium increased commensurate with the degree of mesangial expansion and degree of diabetic nephropathy. Reduction in α2 chain intensity was observed with severe mesangial expansion and in the areas of nodular glomerulosclerosis. In addition, with late disease aberrant expression of α2 and ß2 chains was observed in the mesangium. Glomerular basement membrane in renal disease overexpressed molecules normally present in that location. In summary, the alterations in basement membrane composition in various renal diseases seem to not only reflect the balance between synthesis and degradation of normal basement membrane constituents, but also their aberrant expression.

[Interaction of vasotonic bioeffectors in endothelial dysfunction pathogenesis due to arterial hypertension on aging].

One of the earliest impairments of target-organs due to arterial hypertension (AH) dysfunction is considered. The interrelation between AH and expressiveness of endothelial dysfunctions (ED) degree in the involutive changed vessels is defined. Features of mutual relation vasotonic bioeffectors--oxyde nitrogen (NO) and endothelin-1 (ET-1), interfaced to results of endothelial vasodilation are designated. The technique estimating epy degree of interaction between NO and ET-1 is offered. It is established, that against inertness vasodilation, developing under the combination of involutive and hypertensive damages, maintaining adequate blood flow in the vessel after the mechanical stress induced impact is provided at the expense of increase of speed of systolic and diastolic blood flow, improve the sensitivity of the endothelium to pressure of shift, change the synthesis and secretion of ET-1 and NO.

[Interrelation of endothelial and myocardial dysfunction in persons of elderly age with arterial hypertension].

For the purpose of estimation of peculiarities of interrelation between endothelial dysfunction (ED) and myocardial dysfunction (MD) in elderly persons due to arterial hypertension (AH) 66 patients of elderly age with AH of II stage and 26 persons of similar age without cardiovascular diseases were examined. It is established, that development AH is accompanied by formation of a concentric hypertrophy and concentric remodelling of myocardium, diastolic and systolodiastolic myocardial dysfunction, its expressiveness is interfaced to severity of endothelial dysfunction. Progressing of ED is accompanied by infringements of lipids' metabolism, increasing of their peroxidation activity and decreasing in efficiency of anti-oxidation protection.

Is there a secular decline in motor skills in preschool children?

Current research seems to confirm a secular decline in movement skills in school children. Only few data are available for preschool children and no clear trend can be identified. In the year 2007, height, weight, and motor performance were determined in 726 preschool children [Prevention through Activity in Kindergarten Trial (PAKT)] and compared with historical samples from 1973, 1985, and 1989. There was no difference in height and weight between the samples of 1973 and 2007. Older boys of today were smaller and lighter than those of 1989. Regardless of age, PAKT children fared significantly better in standing long jump than those assessed in 1989. Compared with the sample of 1973, PAKT children did equally well in this task. There were no differences in performance in an obstacle course between children of 1989 and 2007. In balancing backwards, PAKT children performed significantly worse than those in 1985. Regarding target throwing only the PAKT 4-year-olds achieved significantly worse results than those in 1985.Therefore, in preschool children, a secular decline is only evident in some, but not all, motor skills, which may indicate a change in behavior activity over the last decades.

Clinically proven markers of metastasis predict metastatic spread of human melanoma cells engrafted in scid mice.

Metastasis formation is a complex process and as such can only be modelled in vivo. As markers indicating metastatic spread in syngenic mouse models differ significantly from those in man, this study aimed to develop a human melanoma xenograft mouse model that reflects the clinical situation. Six human melanoma cell lines (LOX, MV3, FEMX-1, G361, MeWo and UISO-Mel6) were xenografted into severe combined immunodeficient mice and tumour growth, metastatic behaviour and number of lung metastases were assessed. Tumours and metastases were analysed for HPA binding and expression of CEACAM-1 and L1, all markers indicative of metastasis in clinical studies. Development of primary tumour nodules ranged from 3 weeks (MV3) to 3 months (MeWo). Whereas G361 and FEMX-1 rarely formed lung metastases, MeWo, MV3 and LOX were moderately and UISO-Mel6 was highly metastatic. Similar to clinical studies, HPA, CEACAM1 and L1 indicated metastatic spread in the xenograft melanoma model, but were not all simultaneously expressed in all cell lines. Considering the strongest expression of one marker combined with an absent or low expression of the other two markers, we conclude that LOX is the cell line of choice for analyses of the functional role of HPA-binding glycoconjugates, UISO-Mel6 is ideally suited to study CEACAM1 function in melanoma spread and L1 function can best be modelled using MeWo.

Lessons learned from more than 1,000 pancreas transplants at a single institution.

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.

Development of a peptide-based sandwich ELISA for human tissue prokallikrein with no cross-reactivity from mature kallikrein.

Human tissue prokallikrein is the enzymatically inactive zymogen of a serine proteinase involved in the liberation of vasoactive kinin peptides, and it is supposed that an impaired prokallikrein-to-kallikrein conversion is closely related to certain hypertensive and inflammatory disorders. Progress in understanding the biological role of the proenzyme has been limited by the absence of an accurate assay for the kallikrein precursor. We describe a sandwich enzyme-linked immunosorbent assay to measure human tissue prokallikrein using monospecific anti-peptide antibodies raised against propeptide derivatives. This method could detect a minimum concentration of 60 pg/ml prokallikrein and displayed no cross-reactivity or interference with mature tissue kallikrein. The intra- and inter-assay precision varied from 8-15%, respectively, indicating a reasonable reproducibility of the method. The level of prokallikrein was defined in different human urine samples, and the corresponding dilution curves showed good linearity. The mean recovery of added zymogen was 104%. Prokallikrein immunoassay is the first reported tool for the direct and sensitive quantification of the precursor of tissue kallikrein and should facilitate the precise determination of prokallikrein levels in a variety of biological specimen.

Risk factors for chronic rejection in pediatric renal transplant recipients--a single-center experience.

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).

Altered kidney matrix gene expression in early stages of experimental diabetes.

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.

Outcome of chickenpox in 66 pediatric renal transplant recipients.

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.

The importance of early cyclosporine levels in pediatric kidney transplantation.

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.

Impact of age on renal graft survival in children after the first rejection episode.

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.

Recipient evaluation, preparation, and care in pediatric transplantation: the University of Minnesota protocols.

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.

Chronic renal allograft rejection in the first 6 months posttransplant.

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.

Recurrent hemolytic uremic syndrome in an adult renal allograft recipient: current concepts and management.

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.

Altered expression of matrix metalloproteinase-2, TIMP, and TIMP-2 in obstructive nephropathy.

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.

Structural-functional relationships in Alport syndrome.

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.

Differential distribution of type IV collagen chains in patients with diabetic nephropathy in non-insulin-dependent diabetes mellitus.

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.