Diabetic nephropathy is characterized by albuminuria which proceeds to overt proteinuria. The highly negatively stained HS side chain of heparan sulphate proteoglycan (HSPG) is a major determinant of the charge-dependent permeability of the GBM. We set out to study the presence of HS and HSPG in the GBM of patients with diabetic nephropathy using newly developed monoclonal antibodies, and to compare HSPG expression to the expression of other previously investigated glomerular extracellular matrix compounds. Immunohistochemically, glomerular extracellular matrix components were analysed in 14 renal biopsies of patients with diabetic nephropathy and compared with those of normal control subjects. Monoclonal antibodies used were: JM403 against the HS side chain of GBM HSPG and JM72 against the HSPG-core protein. Also, a polyclonal antiserum (B31) against human GBM-HSPG-core protein was used. Additionally, antibodies were used against collagen types I, III, IV and against alpha 1 (IV)NC, alpha 3(IV)NC and fibronectin. Staining was scored for intensity and for staining pattern by four independent observers who had no previous knowledge of the sample origin. No glomerular staining was seen for collagen type I. Collagen type III was present in some diabetic nodules. Anti-collagen type IV showed a decreased GBM staining in patients with diabetic nephropathy (p = 0.04). With anti-alpha 1 (IV)NC no changes in GBM staining intensity were observed; with anti-alpha 3 (IV)NC brilliant GBM staining was seen in both groups. Increased mesangial staining (p = 0.003) was seen with anti-collagen type IV in biopsies with nodular lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased expression of heparan sulphate has been shown in the glomerular basement membrane of patients with over diabetic nephropathy. Low- molecular-weight heparin (LMWH) is a highly sulphated glycosaminoglycan with strong structural and functional similarities to heparan sulphate. In a first study, we set out to assess if LMWH could decrease the urinary albumin excretion rate (AER) in diabetic patients with over nephropathy. Six patients entered a randomized, double-blind, placebo-controlled crossover study with treatment episodes of 1 month, separated by a 1-month wash-out. Patients self-administered prefilled syringes with either placebo or LMWH (enoxaparin 40 mg/0.4 ml) at bedtime. Baseline AER levels before either treatment period were similar. In contrast to placebo, AER significantly decreased from 447 (181-1102) to 295 (100-873) micrograms/min after 1 month treatment with LMWH (P < 0.05). Compared to placebo, the effect of LMWH did not reach statistical significance in these six patients after 1 month treatment (P = 0.16). Haemodynamic variables including glomerular filtration rate and filtration fraction did not change during enoxaparin treatment. We observed a favourable effect on AER during LMWH treatment in diabetic patients with over nephropathy. These data suggest that long-term treatment trials in a larger group of patients may potentially demonstrate a new therapeutic option for patients with over diabetic nephropathy.

This review provides a compact overview on the contribution of mutations in mtDNA to the pathogenesis of diabetes mellitus, with emphasis on the A3243G mutation in the tRNA(Leu, UUR) gene. This mutation associates in most individuals with maternally inherited diabetes and deafness (MIDD) whereas in some other carriers the MELAS syndrome or a progressive kidney failure is seen. Possible pathogenic mechanisms are discussed especially the question why particular mutations in mtDNA associate with distinct clinical entities. Mutations in mtDNA can affect the ATP production, thereby leading to particular clinical phenotypes such as muscle weakness. On the other hand mtDNA mutations may also alter the intracellular concentration of mitochondrial metabolites which can act as signalling molecules, such as Ca or glutamate. This situation may contribute to the development of particular phenotypes that are associated with distinct mtDNA mutations.

In Type 1 diabetes mellitus all tissues are exposed to hyperglycaemia, but only a subset (30±40 %) of diabetic patients develop diabetic kidney disease [1,2]. According to the Steno hypothesis, albuminuria and associated complications result from a genetic polymorphism of enzymes involved in the metabolism of heparan sulphate proteoglycans (HSPG) [2].HSPG consists of a core protein with heparan sulphate (HS) glycosaminoglycan side chains. Sulphate Diabetologia (1998) Summary In diabetic nephropathy, expression of glycosaminoglycan side chains of heparan sulphate proteoglycan in the glomerular basement membrane is reduced proportionally to the degree of proteinuria. We performed a cross-sectional study to evaluate whether non-vascular basement membranes also show a decrease in heparan sulphate side chain staining in patients with diabetic nephropathy. We evaluated the skin basement membrane for extracellular matrix components in the following groups: control subjects (n = 16); patients with Type 1 diabetes and normoalbuminuria (n = 17), microalbuminuria (n = 7), and macroalbuminuria (n = 16); patients with Type 1 diabetes and diabetic nephropathy undergoing renal replacement therapy (n = 13); and non-diabetic patients undergoing renal replacement therapy (n = 21). The following antibodies were used for this immunohistochemical study: monoclonal antibodies against the heparan sulphate side chain (JM403) and core protein (JM72) of the glomerular heparan sulphate proteoglycan; polyclonal antibodies against the core protein (B31); polyclonal antibodies against collagen types I, III, and IV, fibronectin, and laminin; and monoclonal antibodies against the noncollagenous domain of a1(collagen IV) and a3(collagen IV), against transforming growth factor b(2G7), and against advanced glycosylation end products (4G9). Expression of heparan sulphate side chains was reduced in the skin basement membrane of patients with overt diabetic nephropathy, of those with Type 1 diabetes undergoing renal replacement therapy, and those with non-diabetic renal failure. Increased intensity of staining was found for collagen type I and advanced glycosylation end products in patients with diabetic nephropathy. Changes in the extracellular matrix of the skin basement membrane seem to be similar to those in the glomerular basement membrane. These findings support the suggestion that patients with diabetic nephropathy also have altered heparan sulphate and collagen staining in extrarenal basement membranes. However, patients with non-diabetic renal failure also had reduced expression of heparan sulphate in the skin basement membrane, suggesting that this finding is not specific for diabetic nephropathy. [Diabetologia (1998) Keywords Advanced glycosylation end products, albuminuria, basement membrane, collagen, Type 1 diabetes mellitus, diabetic nephropathy, epidermodermal junction basement membrane zone, fibroblasts, heparitin sulphate, skin.Received: 13 November 1997 and in revised form: 10 February 1998Corresponding author: Dr. J. W. van de...

This study examined the effect of acute hyperglycaemia, induced by intravenous glucose, on gall bladder motility. Six healthy volunteers were studied in random order on three occasions during normoglycaemia and hyperglycaemia with blood glucose concentrations stabilised at 8 and 15 mmol/l. Gail bladder volumes, measured with ultrasonography, were studied before and during infusion of stepwise increasing doses of cholecystokinin 05, and 1.0 IDU.kg-1.h-1).