Diabetic nephropathy as a model of reversibility of established renal lesions.
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Animals↗
Biomedical subjects
P Fioretto
Publications and source records attributed to P Fioretto.
Renal function in noninsulin-dependent diabetes mellitus patients treated with angiotensin-converting enzyme inhibitors and calcium channel blockers.
BACKGROUND: Data have not shown consistent effects with calcium channel blockers on the course of renal function in patients with noninsulin-dependent diabetes mellitus (NIDDM) who have hypertension alone or in association with renal damage. The differences between the antiproteinuric effects of subclasses or formulations of calcium channel blockers and the heterogeneity of renal lesions may contribute to the discrepancy in these data. Clinical studies conducted by the authors and other recent data that describe the course of renal dysfunction in hypertensive NIDDM patients treated with antihypertensive agents are reviewed. Renal structural changes were also evaluated. RESULTS: Most available data indicate that angiotensin-converting enzyme inhibitors and dihydropyridine and nondihydropyridine calcium channel blockers produce similar effects on glomerular filtration rate. In one study of patients achieving intensified, strict control of blood pressure (target<140/85 mmHg) with either cilazapril or amlodipine, glomerular filtration rate declined by 2.03+/-0.66 ml/ min/1.73 m2 per year and 2.01+/-0.71 ml/min/1.73 m2 per year, respectively, in the subgroup with normoalbuminuria and by 2.15+/-0.69 ml/min/1.73 m2 per year and 2.33+/-0.83 ml/min/ 1.73 m2 per year, respectively, in the subgroup with microalbuminuria. Renal lesions in NIDDM patients were found to be structurally heterogeneous and glomerular filtration rate appeared to decline only in patients with renal structural changes typical of NIDDM. CONCLUSIONS: The extent of blood pressure control, rather than the method by which this is accomplished, is the most important factor in determining the evolution of incipient nephropathy in hypertensive NIDDM. The kidneys of microalbuminuric NIDDM patients are structurally heterogeneous with less than one-third of patients having 'typical' diabetic nephropathology.
Angiotensin-Converting Enzyme Inhibitors↗
Pathophysiology of diabetic complications.
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Animals↗
Growth factors and diabetic nephropathy: kidney structure and therapeutic interventions.
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Diabetes Mellitus, Type 1↗
Elevated sodium-lithium countertransport activity in erythrocytes is predictive of the development of microalbuminuria in IDDM.
Pathogenetic mechanisms other than the quality of metabolic control may play a role in the development of diabetic nephropathy. Some cross-sectional studies have shown that elevated erythrocyte sodium-lithium countertransport (Na+/Li+ CT) activity may be linked to incipient or overt nephropathy in insulin-dependent diabetic (IDDM) patients. The aim of the present work was to ascertain if high erythrocyte Na+/Li+ CT activity anticipates the development of microalbuminuria in IDDM patients. Evaluation of this cation transport system was carried out in 159 normotensive, normoalbuminuric IDDM patients, who were divided into two groups: those with values above (Group A) and those with values below (Group B) the median level in the overall population (300 mumol/erythrocytes x h). A total of 79 patients in Group A and 80 in Group B underwent periodic examinations over a similar time period (5.2 years, range 3.3-7.4 years and 5.4 years, range 3.4-7.5 years, respectively). Median sodium-lithium countertransport activity was stable when evaluated after 2 and 4 years of follow-up. Only seven patients were excluded from the protocol because changes in their sodium-lithium countertransport activity placed them on the other side of the median value with respect to their baseline measurement. Thus, 152 patients completed the study (76 in Group A and 76 in Group B). Of the 76 patients in Group A, 17 developed persistent microalbuminuria (22.3%). The number of patients in Group B showing persistent microalbuminuria was significantly lower (4 of 76; 5.2%; p < 0.01). The sensitivity of erythrocyte Na+/Li+ CT in predicting the development of microalbuminuria was 85% and its specificity was 55%. Seven patients of Group A and five of Group B developed arterial hypertension. Subjects in Group A had significantly higher mean HbA1c values of twice yearly measurements than those in Group B (9.6 +/- 1.7 vs 8.3 +/- 1.7%, p < 0.002, mean +/- SD) despite similar daily insulin requirements. Systolic and diastolic blood pressure levels were also evaluated every 6 months and were significantly higher in the Group A than in the Group B patients, although on average within the normal range. The odds ratio for developing persistent microalbuminuria in IDDM with elevated baseline erythrocyte Na+/Li+ CT activity after adjustment for gender and baseline albumin excretion rate, and mean 6 monthly plasma creatinine, HbA1c and systolic and diastolic blood pressure levels was 4.2 (95% confidence intervals 2.0-11.1). It was also found that the percentage of offspring having both parents with Na+/Li+ CT activity above the median value was significantly higher in Group A than in Group B (Group A vs Group B: 35 vs 19%; p < 0.01). On the contrary the percentage of offspring whose erythrocyte Na+/Li+ CT was lower in both parents was lower in Group A than in Group B: 10 vs 38%, p < 0.01). Parents of Group A offspring had arterial hypertension more frequently than those of Group B. These results indicate that erythrocyte Na+/Li+ CT activity is a useful diagnostic tool in identifying normotensive, normoalbuminuric patients who may be predisposed to develop persistent microalbuminuria. This disorder in the cation transport system is associated with poor metabolic control, higher blood pressure, and male sex; it also appears to be, at least partly, genetically transmitted.
Adolescent↗
Down-regulation of glomerular matrix metalloproteinase-2 gene in human NIDDM.
Regulation of mesangial matrix deposition is a dynamic phenomenon involving synthetic and degradative processes. The latter involve a number of matrix metalloproteinases (MMP) and tissue inhibitors of matrix metalloproteinases (TIMP). Experimental studies suggest that mesangial matrix degradation is inhibited in diabetic nephropathy, and that this phenomenon has a pathogenic role. The expression of genes for MMP2 and TIMP2 in human diabetic nephropathy was investigated. Reverse transcription polymerase chain reaction was carried out in microdissected glomeruli and tubulo-interstitium obtained from kidney biopsies. We studied 16 NIDDM patients, 5 patients with glomerulonephritis or chronic kidney transplant rejection, and 5 normal control subjects. Albumin excretion rate and renal histology for NIDDM patients were available. Contrary to TIMP2 which was expressed both in tubulo-interstitium and glomeruli in almost all renal biopsies, MMP2 gene down-regulation was observed in glomeruli from all NIDDM patients, irrespective of the albumin excretion rate, and of renal histology. In contrast, this gene was expressed in biopsies from other subjects (chi(2) = 20.6; p = 0.000). In conclusion, this study demonstrates that: 1) in glomeruli of NIDDM patients the MMP2 gene is down-regulated; 2) in biopsies of NIDDM patients the MMP2/TIMP2 pattern is peculiar for NIDDM; 3) the MMP2 gene down-regulation is observed in all NIDDM patients, irrespective of the level of albuminuria and of renal histology. MMP2 gene down-regulation seems to be a molecular epiphenomenon of diabetes, rather than a marker of diabetic nephropathy.
Adult↗
Renal structural changes in non-insulin-dependent diabetes mellitus.
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Albuminuria↗
Glomerular changes in normo- and microalbuminuric patients with long-standing insulin-dependent diabetes mellitus.
Normalbuminuric patients who have long-standing IDDM have a wide range of renal structure, from within normal limits to advanced lesions that overlap those of patients who have high levels of MA and border on those seen in patients who have overt DN. Patients who have low-level MA have reduced glomerular structure similar to that of patients who have NA. Low GFR, hypertension, or both can occur in patients who have NA or low-level MA and are associated with more advanced lesions. Patients who have MA and AER greater than 45 mg/24 hr have more advanced lesions than do patients with NA or low-level MA, but similar lesions are present in these patients whether AER is greater than or less than 100 mg/24 hr. Increasing AER in NA and MA patients who have long-standing IDDM is associated with GBM and mesangial expansion. A structural basis for MA cannot currently be deduced from studies of glomerular epithelial cell fine structure, capillary wall charge site analysis, or immunohistochemical studies of renal ECM composition. Hemodynamic adaptations to mesangial expansion and reduced filtration surface and, perhaps, hydraulic conductivity may accelerate glomerular damage, as expressed by increasing AER. Microalbuminuria derives its clinical utility in IDDM, as it identifies a population of patients at statistically increased risk of progression to overt DN by acting as a marker of already well-established DN lesions. Although MA is currently the best of the widely used indicators of DN risk, it is not precise. Therapies that reduce MA may ultimately slow or prevent progression toward ESRD, but this finding requires confirmation by demonstrating that a given treatment strategy can preserve GFR.
Albuminuria↗
Renal structure and function in non-insulin dependent diabetic patients with microalbuminuria.
We have recently described heterogeneity in renal structure in non-insulin-dependent diabetic patients (NIDDM) with microalbuminuria (MA; defined as albumin excretion rate from 20 to 200 micrograms/min). Thus, at variance with IDDM patients, "typical" diabetic glomerulopathy by light microscopy is observed only in a third of NIDDM with MA (Category II, CII). Further, despite persistent MA, 30% of NIDDM have normal or near normal renal structure (Category I, CI). Another one-third shows "atypical" patterns of renal injury with absent or mild diabetic glomerular changes, associated with disproportionately severe tubulointerstitial lesions and/or arteriolar hyalinosis and global glomerular sclerosis (Category III, CIII). The aims of this study were to evaluate whether similar patterns of renal lesions could be confirmed in a larger group of NIDDM with MA and to investigate tubular function in order to understand the mechanisms underlying MA in NIDDM patients. Renal biopsies were performed in 53 NIDDM with MA. Categories I, II and III were found in 41%, 26% and 33% of NIDDM with MA, respectively. All 8 patients with proliferative diabetic retinopathy were in CII. We also studied the urinary daily excretion rate of alpha 1-microglobulin (alpha 1 m), a low molecular weight protein, which is a useful indicator of tubular function. alpha 1 m was markedly increased only in CII patients (CI vs. CII vs. CIII: 6.2 +/- 1.2 vs. 13.7 +/- 2.1 vs. 7.3 +/- 0.9 mg/day, ANOVA, P < 0.01). In conclusion, we confirm that there is heterogeneity in renal structure in NIDDM patients with MA. This heterogeneity is not due to renal diseases other than diabetes. Increased alpha 1 m and proliferative retinopathy are useful indicators of the subgroup of MA NIDDM patients with typical diabetic glomerulopathy. It is suggested that diabetic microangiopathy explains the simultaneous occurrence of typical diabetic glomerulopathy, proliferative retinopathy and tubular dysfunction in a subgroup of NIDDM patients with MA.
Albuminuria↗
Diabetic nephropathy as a model for the use of renal structural endpoints in clinical trials.
Slowly developing renal diseases (SDRD) such as diabetic nephropathy (DN) and hypertensive nephrosclerosis constitute the large majority of disorders leading to end-stage renal disease (ESRD). These disorders are characterized by years to decades without renal functional abnormalities during which renal structural changes are developing. The earliest renal functional abnormalities [such as microalbuminuria in patients with insulin dependent diabetes mellitus (IDDM)] are often associated with already well established renal lesions that may progress independent of the initiating cause. Since the clinical manifestations of these disorders are dependent upon established structural changes, prevention of the early lesions seems a logical goal and thus a useful endpoint for clinical trials. Functional endpoints are impractical at these early stages as they would take too long to manifest. Diabetic nephropathy in IDDM patients is a useful model for such study design, since there is sufficient knowledge of the natural history of the disorder and of the important structural endpoints to allow for the statistical power calculations crucial for study design. More information regarding natural history and structural-functional relationships is needed in non-insulin dependent diabetes, hypertension, and other SDRD before intervention trials using renal structural endpoints can be developed for these important causes of ESRD.
Animals↗
Patterns of renal injury in NIDDM patients with microalbuminuria.
Microalbuminuria predicts overt nephropathy in non-insulin-dependent diabetic (NIDDM) patients; however, the structural basis for this functional abnormality is unknown. In this study we evaluated renal structure and function in a cohort of 34 unselected microalbuminuric NIDDM patients (26 male/8 female, age: 58 +/- 7 years, known diabetes duration: 11 +/- 6 years, HbA1c: 8.5 +/- 1.6%). Systemic hypertension was present in all but 3. Glomerular filtration rate (GFR) was 101 +/- 27 ml.min-1.1.73 m-2 and albumin excretion rate (AER) 44 (20-199) micrograms/ min. Light microscopic slides were categorized as: C I) normal or near normal renal structure; C II) changes "typical" of diabetic nephropathology in insulin-dependent diabetes (IDDM) (glomerular, tubulo-interstitial and arteriolar changes occurring in parallel); C III) "atypical" patterns of injury, with absent or only mild diabetic glomerular changes associated with disproportionately severe renal structural changes including: important tubulo-interstitial with or without arteriolar hyalinosis with or without global glomerular sclerosis. Ten patients (29.4%) were classified as C I, 10 as C II (29.4%) and 14 as C III (41.2%); none of these patients had any definable non-diabetic renal disease. GFR, AER and blood pressure were similar in the three groups, while HbA1c was higher in C II and C III than in C I patients. Diabetic retinopathy was present in all C II patients (background in 50% and proliferative in 50%). None of the patients in C I and C III had proliferative retinopathy, while background retinopathy was observed in 50% of C I and 57% of C III patients. In summary, microalbuminuric NIDDM patients are structurally heterogeneous with less than one third having "typical" diabetic nephropathology. The presence of both "typical" and "atypical" patterns of renal pathology was associated with worse metabolic control, suggesting that hyperglycaemia may cause different patterns of renal injury in older NIDDM compared to younger IDDM patients.
Aged↗
Growth phenotype of cultured skin fibroblasts from IDDM patients with and without nephropathy and overactivity of the Na+/H+ antiporter.
An increased activity of the Na+/H+ antiporter in cells from patients with insulin-dependent diabetes mellitus (IDDM) has been proposed as a potential marker of nephropathy. We evaluated Na+/H+ antiporter activity and its relationship to DNA and protein synthesis in cultured skin fibroblasts from patients with IDDM classified as having either overt nephropathy or absence of nephropathy on the basis of urinary albumin excretion and kidney biopsy findings. In IDDM patients with overt nephropathy, Na+/H+ antiporter activity in serum stimulated cells was increased as compared to cells from control subjects (9.62 +/- 0.89 vs. 5.67 +/- 0.97 mmol H+/min, P < 0.005, respectively) and cells from IDDM patients without nephropathy (7.22 +/- 0.67 mmol H+/min, P < 0.025). By contrast, in cells made quiescent by serum deprivation Na+/H+ antiporter activity was lower than in serum-stimulated cells and there were no significant differences between the three groups. DNA synthesis assessed by [3H] thymidine incorporation was increased in the IDDM group with nephropathy as compared to the group without nephropathy (138 +/- 14 vs. 105 +/- 13 cpm/1000 cells, respectively, P < 0.05) and as compared to control subjects (65 +/- 11 cpm/1000 cells, P < 0.001). By contrast, protein synthesis assessed by [14C] L-leucine incorporation was not increased in fibroblasts from IDDM patients with nephropathy, suggesting that cellular hypertrophy is not a feature of their altered growth phenotype. After chronic inhibition of the Na+/H+ antiporter using EIPA (25 microM), [3H] thymidine incorporation was reduced by about 20% both in cells from IDDM patients and controls. This parameter therefore remained higher in cells from IDDM patients with nephropathy than in those from controls (81 +/- 16 vs. 40 +/- 6 cpm/1000 cells, P < 0.05), while in cells from IDDM patients without nephropathy [3H] thymidine incorporation after EIPA (56 +/- 7.0 cpm/1000 cells) was intermediate between cells from controls and IDDM patients with nephropathy. We argue that cultured skin fibroblasts from IDDM patients, with nephropathy display an abnormal growth phenotype characterized by cell hyperplasia. This growth phenotype is associated with overactivity of the Na+/H+ antiporter during serum stimulation but not when cells are made quiescent and persists after inhibition of the Na+/H+ antiporter. Our data, therefore, further shows that overactivity of the Na+/H+ antiporter is not required for the expression of the altered growth phenotype of cultured skin fibroblasts from IDDM patients with nephropathy.
Adult↗
Plasma clearance rate of 51Cr-EDTA provides a precise and convenient technique for measurement of glomerular filtration rate in diabetic humans.
It has not yet been fully clarified whether the plasma or renal clearance approach is the most reliable to investigate GFR in humans. The study presented here aimed to compare plasma decay with renal clearance of 51Cr-EDTA in 27 diabetic patients with patterns of renal function broadly dispersed in a wide range of values. Moreover, the comparison was also performed with renal clearance of nonlabeled iothalamate in a subgroup of 17 patients. A biexponential function was found to fulfill statistical and heuristic criteria for the modeling analysis of plasma 51Cr-EDTA decay with 19 samples after bolus intravenous 51Cr-EDTA injection. Individual GFR values from 51Cr-EDTA plasma clearance highly correlated with those from renal clearance (r2 = 0.977, P < 0.0001), but resulted on average about 2.5 mL.min-1.1.73 m-2 higher (66.8 +/- 6.5 mL.min-1.1.73 m-2 (mean +/- SE) versus 64.3 +/- 6.4, P < 0.02). This difference remained relatively constant from patients with normal renal function to those with impaired renal function, suggesting that the plasma clearance is slightly less accurate than renal clearance approach because of a constant extrarenal clearance rate. In the subgroup studied, a similar difference was found between GFR values from 51Cr-EDTA plasma clearance (84.7 +/- 7.3) and renal clearance of iothalamate (82.8 +/- 7.3), although not statistically significant (P = 0.4). Individual GFR values well correlated (r2 = 0.913, P < 0.0001). The precision and reproducibility of the experimental approaches were assessed by comparing three coefficients of variation: (1) CVb of the bolus injection, because of measurement errors; (2) CVc of the continuous infusion, which additionally includes errors of urine volume measurement and physiological variability in the same day; and (3) CVr of repeated measurements by using bolus injection, which also accounts for physiological variability in different days. CVc of iothalamate and 51Cr-EDTA infusions were 7.5 +/- 1.9% and 7.4 +/- 1.2% respectively. CVb and CVr of bolus injection of 51Cr-EDTA were 2.6 +/- 0.3% and 3.5 +/- 0.8% respectively. CVb and CVr of bolus injection of 51Cr-EDTA, but not CVc of iothalamate and 51Cr-EDTA infusions were twofold to tenfold lower than the percent yearly change reported in IDDM and NIDDM patients. More particularly, CVr was significantly less than CVc. In order to make the test less cumbersome, a reduced sampling schedule with seven samples was designed and validated. GFR measured with seven samples was 66.1 +/- 6.4 (P = 0.1 when compared with the full 19-sample schedule) with a CVb of 3.5 +/- 0.5%. This seven-sample protocol was not different from that obtained with the previously described simplified method of Brøchner-Mortensen (63.9 +/- 6.8, P = 0.16), yet yielding a statistically more accurate estimate (coefficient of variation for Brøchner-Mortensen method = 12.1 +/- 2.9, P = 0.004). Moreover, only bolus injection, along with modeling analysis of plasma clearance rate, allows the accurate measurement of the extracellular fluid volume, an important parameter in diabetic patients. It was concluded that the reduced seven-plasma sample protocol is able to detect as small as 4 to 5% changes per year in a single patient. Moreover, it provides precise and accurate estimate of GFR in diabetic patients with hyperfiltration, who are postulated to be at higher risk to develop renal damage.
Chromium Radioisotopes↗
Effects of cilazapril and amlodipine on kidney function in hypertensive NIDDM patients.
Contrasting information has been reported concerning the course of renal function in NIDDM with hypertension alone or in association with renal damage. The aim of the present study was to elucidate the course of the glomerular filtration rate (GFR) in hypertensive NIDDM patients during antihypertensive therapy. Furthermore, we compared the effects of ACE inhibitors (cilazapril, Inibace, Roche, Milan, Italy) and Ca(2+)-channel blockers (amlodipine, Norvasc, Pfizer, Rome, Italy). Of the hypertensive NIDDM patients attending the outpatient's clinic of the internal medicine departments of the University of Padova and Sassari, 44 participated in the present study. Of these patients, 26 were normoalbuminuric and 18 microalbuminuric. They were randomly treated with either cilazapril or amlodipine. The target of antihypertensive treatment was a value < 140 mmHg for systolic and 85 mmHg for diastolic blood pressure (BP). Microalbuminuria was defined as an albumin excretion rate (AER) between 20 and 200 micrograms/min. GFR was measured by plasma clearance of 51Cr-labeled EDTA at baseline and every 6-12 months during a 3-year follow-up interval. A significant decrease was observed in the values of GFR, AER, and systolic and diastolic BP in normoalbuminuric and microalbuminuric patients during antihypertensive therapy. The GFR fall in the overall population of NIDDM patients was significantly and inversely related to the decrease of mean BP (diastolic + 1/3 pulse pressure) (r = -0.80, P < 0.0001) but not to that of HbA1c, triglycerides, and BMI. The GFR decline (mean +/- SE) per year in the normoalbuminuric patient was 2.03 +/- 0.66 ml.min-1 x 1.73 m-2 (95% CI 0.92-3.17) during cilazapril and 2.01 +/- 0.71 ml.min-1 x 1.73 m-2 (95% CI 0.82-3.11) during amlodipine therapy. The GFR decline per year in the microalbuminuric patient was 2.15 +/- 0.69 ml.min-1 x 1.73 m-2 (95% CI 0.86-3.89) during cilazapril and 2.33 +/- 0.83 ml.min-1 x 1.73 m-2 per year (95% CI 1.03-3.67) during amlodipine therapy. Cilazapril and amlodipine lowered AER to a similar extent in normoalbuminuric and microalbuminuric patients. No significant changes were observed concerning other clinical and biochemical features between the two antihypertensive therapies and particularly HbA1c, BMI, triglycerides, and cholesterol plasma values. These results support the tenet that arterial hypertension plays a pivotal role in contributing to renal damage in NIDDM, even when AER is normal. However, the degree of BP control, with both cilazapril and amlodipine, can successfully delay the slope of GFR decline in hypertensive NIDDM patients with or without incipient nephropathy.
Adult↗
Cyclosporine associated lesions in native kidneys of diabetic pancreas transplant recipients.
Five years of normoglycemia following pancreas transplantation (PT) does not ameliorate glomerular lesions in patients with their own kidneys and with long-term insulin-dependent diabetes (IDDM) (Lancet 342:1193, 1993). All these patients received cyclosporine (CsA) as part of their immunosuppression. Here we examined the relationship of CsA dose and blood levels to the presence and severity of CsA-associated renal lesions and changes in renal function in these PT patients. Renal biopsies were taken before (0) and two and five years after PT from 13 non-uremic IDDM patients and were compared with baseline and five year biopsies from 10 IDDM controls (C). CsA dose was reduced from 10 +/- 3 mg/kg/day in the first month to 5 +/- 2 in the fifth year post-PT. Creatinine clearance (CCr) decreased by 34% at one year post-PT and was stable thereafter, and did not change in C. The decline in CCr from 0 to one year was related to CsA blood levels and dose (P < 0.005) at one year. Cortical interstitial volume fraction [Vv(Int/Cortex)], the index of tubular atrophy, and % sclerotic glomeruli increased significantly from 0 to five years post-PT (P < 0.005, 0.01 and 0.001, respectively), but did not change in C. There was no significant change from 0 to two years post-PT in these lesions, while there was a clear progression from two to five years. Mean CsA dose and blood levels in the first year post-PT correlated with the increase (delta) in Vv(Int/Cortex) at five years (P < 0.05 for both).(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Sequential renal biopsies in insulin-dependent diabetic patients: structural factors associated with clinical progression.
Quantitative structural studies in native kidneys of IDDM patients have almost all been cross sectional, and little is known regarding the dynamics of progression of structural lesions in relation to clinical progression. It has been suggested that interstitial may be more important than glomerular changes in determining functional outcome. This study evaluated renal structure in sequential biopsies from IDDM patients with established renal lesions to determine whether glomerular, arteriolar and interstitial changes progress together and in concordance with measures of renal function. Eleven long-term IDDM patients [age 29 +/- 10 years, duration 17 +/- 7 years (mean +/- SD)] had renal function studies and kidney biopsies performed at two occasions 5.6 +/- 1.6 years apart. HbA1 as well as creatinine clearance (CCr) did not change over this time; albumin excretion rate (AER) increased from 12 (6 to 280) to 19 (5 to 2462) [median (range)] mg/24 hr (P < 0.03). AER increased in the three patients with abnormal albuminuria at first observation, and two normoalbuminuric patients became microalbuminuric. Blood pressure (BP) did not change; however, the number of patients on antihypertensive therapy increased from 1 to 5. All structural parameters were abnormal at first evaluation. Mesangial fractional volume [Vv(mes/glom)] and mean glomerular volume increased and the surface density of the peripheral glomerular basement membrane (GBM) decreased, while GBM width did not change over the five years of the study. Also, arteriolar hyalinosis lesions progressed, while the fractional volume of cortical interstitium [Vv(interstitium/cortex)] and the percent of globally sclerosed glomeruli did not change. The only structural change that correlated with the increasing AER was the change in Vv(mes/glom). Changes in structural parameters, AER or CCr did not significantly correlate with baseline BP or change in BP over the five years. Although based on a small number of patients, this study suggests that at the stage of disease where renal lesions are established and where some IDDM patients are in transition to microalbuminuria or early clinical nephropathy, continuing mesangial expansion is the central variable. Interstitial changes were not occurring over this time. Progressive interstitial expansion at the later stages of diabetic nephropathy may thus be consequent to advanced diabetic glomerular injury.
Adult↗
Peripheral, rather than hepatic, insulin resistance and atherogenic lipoprotein phenotype predict cardiovascular complications in NIDDM.
Microalbuminuria, hypertension and hyperinsulinaemia are three independent risk factors for cardiac disease in non insulin-dependent diabetes (NIDDM). However, it is unknown to what extent hyperinsulinaemia reflects resistance to insulin action at hepatic, extrahepatic or at both sites. A cross-sectional study from our Department showed that peripheral insulin resistance, hypertension, microalbuminuria and lipid abnormalities are associated in NIDDM. Non diabetic individuals with the so-called 'atherogenic lipoprotein phenotype', characterized by small dense low density lipoproteins (LDL subclass pattern B) have up to 3-fold higher risk of myocardial infarction. The aim of the present study was to investigate whether impaired peripheral insulin sensitivity, during euglycaemic-hyperinsulinaemic clamp, as well as abnormalities in lipid concentrations and LDL size, predict abnormalities in albumin excretion rate, blood pressure and cardiac function in 73 consecutive normotensive (< 85 mmHg diastolic level) and normoalbuminuric (< 15 micrograms min-1 daily albumin excretion rate) NIDDM patients. These patients showed a bimodal distribution of whole body glucose utilization rate, a parameter of peripheral insulin sensitivity. The cut-off point between the two modes of distribution was located close to the mean value minus one standard deviation in a population of 24 control subjects. Therefore, this latter value was used to identify two subgroups inside the overall population of NIDDM patients, i.e. 28 patients (group 1), with whole body glucose utilization rate, above, and 45 patients (group 2), below, the mean value minus 1 SD in the 24 controls.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Glomerular structure in nonproteinuric IDDM patients with various levels of albuminuria.
Although microalbuminuria is known to foretell the later development of overt proteinuria in patients with insulin-dependent diabetes mellitus (IDDM), different investigators have reported different levels of albuminuria as being predictive. However, whether different levels of albuminuria reflect differences in glomerular structure is not well known. In this study, we divided a cohort of 66 nonproteinuric long-standing (duration 20 +/- 7 years) IDDM patients, who had both renal functional and structural studies performed, into four groups according to their urinary albumin excretion rate (AER). The several different levels of microalbuminuria previously reported to be predictive served to demarcate these groups: group I, AER < or = 22 mg/24 h (upper limit for normal in our laboratory) (33 patients); group II, AER 23-45 mg/24 h (11 patients); group III, AER 46-100 mg/24 h (13 patients); and group IV, AER 101-220 mg/24 h (9 patients). Creatinine clearance was similar in groups I, II, and III but was lower in group IV. Systemic hypertension was present in five patients in group I, one in group II, seven in group III, and five in group IV. Mean values for glomerular basement membrane (GBM) width and volume fraction of the mesangium [Vv(mes/glom)] were greater in all groups than in a group of 52 age-matched normal kidney donors (P < 0.0001). Also, filtration surface density [Sv(PGBM)], inversely related to Vv(mes/glom) (r = 0.61, P < 0.0001), was reduced in all diabetic groups compared with the normal group (P < 0.0001). Structural measures were identical in group I and II.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗