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L Tarnow

Publications and source records attributed to L Tarnow.

At least 55 records · Page 3Linked to original sources
PubMed1998

[The significance of deletion polymorphism in the ACE gene for progression of diabetic nephropathies treated with ACE inhibitors].

The aim of the study was to evaluate the effect of an insertion/deletion polymorphism of the angiotensin converting enzyme (ACE) gene on progression of diabetic nephropathy. We performed an observational follow-up study of 35 patients with insulin-dependent diabetes and diabetic nephropathy. Patients were investigated during captopril treatment for a median of seven (range three to nine) years. Eleven patients were homozygous for the deletion allele (DD) and 24 were hetero- or homozygous for the insertion allele (ID + II). The two groups had comparable glomerular filtration rate, albuminuria and blood pressure at baseline and captopril induced nearly the same mean reduction in blood pressure--to 103 (SD 5) mm Hg in the DD-group and 102 (8) mm Hg in the ID + II-group. The rate of decline in glomerular filtration rate was significantly steeper in the DD group than in the other group (mean 5.7 (SD 3.7) versus 2.6 (2.8) ml/min/year, p = 0.01). In conclusion, the deletion polymorphism in the ACE gene reduces the long term beneficial effect of ACE inhibition on the progression of diabetic nephropathy in patients with insulin dependent diabetes.

Adult↗
PubMed1998

Effects of nisoldipine and lisinopril on microvascular dysfunction in hypertensive Type I diabetes patients with nephropathy.

1. Our objective was to compare the effect of a long-acting calcium antagonist (nisoldipine) compared with an angiotensin-converting enzyme inhibitor (lisinopril) on the non-neurogenic regulation of the microvascular blood flow in hypertensive Type I diabetes patients with diabetic nephropathy.2. We performed a 1-year double-blind, double-dummy randomized controlled study comparing nisoldipine (20-40 mg once daily) with lisinopril (10-20 mg once daily) in 48 hypertensive Type I diabetes patients with diabetic nephropathy. For comparison, 22 age-matched normotensive healthy control subjects were included. Measurements were performed at baseline and after 1 year of antihypertensive treatment. The minimal vascular resistance and distensibility (stiffness) of resistance vessels in skin and skeletal muscle were measured using the local isotope washout method.3. Mean arterial pressure was reduced to the same extent in both groups: nisoldipine, 113+/-2.1 to 105+/-1.6 mmHg (P<0.001); lisinopril, 110+/-2.7 to 101+/-2.1 mmHg (P<0.002) (controls, 88+/-2.2 mmHg; P<0.0001 compared with diabetic patients). Nisoldipine improved the skin vascular distensibility from 28+/-3.3 to 43+/-3.8% (P<0.005) and decreased skin minimal vascular resistance from 16.9+/-1.0 to 13.6+/-0.8 mmHg.ml-1.min.100 g (P<0. 02). Lisinopril had no significant effect on skin vascular distensibility (40+/-4.0% and 41+/-4.4%), but minimal vascular resistance tended to diminish (18.1+/-0.9 to 15.8+/-1.3 mmHg.ml-1. min.100 g (P=0.09). Nisoldipine significantly increased the skin distensibility (P=0.05) after 1 year of antihypertensive treatment compared with lisinopril.4. The control group had a skin vascular distensibility of 54+/-3.2% and a minimal vascular resistance of 10. 8+/-0.7 mmHg.ml-1.min.100 g, both significantly different from the values in the diabetic groups (P<0.0001 for all). Skeletal muscle vascular distensibility was unaltered after 1 year of treatment with both nisoldipine (22+/-3.3% and 19+/-2.7%) and lisinopril (19+/-2.1% and 24+/-2.5%), but was reduced compared with a control value of 43+/-3.7% (P<0.0001 for diabetes patients versus controls). However, neither nisoldipine nor lisinopril had any effect on the increased minimal vascular resistance or the reduced skeletal muscle distensibility.5. Enhanced thickening of the basement membranes of the terminal arteriolar wall was found in skin biopsy specimens in 91% of diabetic patients and 38% only in control subjects (P<0. 000001 both before and after treatment for diabetic patients versus controls). There was no significant effect of antihypertensive treatment on arteriolar hyalinosis.6. The reduction in systemic blood pressure was identical during 1 year of treatment with nisoldipine or lisinopril. The abnormal arteriolar stiffness was more pronounced in the group treated with nisoldipine than with lisinopril and only nisoldipine compared with lisinopril improved the abnormal arteriolar stiffness and minimal vascular resistance in the skin. This suggests that nisoldipine can reverse the peripheral skin perfusion and thereby improve the local protection against development of ischaemic skin lesions in Type I diabetes patients with clinical diabetic nephropathy.

Adult↗
PubMed1998

Angiotensin converting enzyme gene polymorphism and ACE inhibition in diabetic nephropathy.

The antiproteinuric effect of angiotensin converting enzyme (ACE) inhibition in insulin-dependent diabetes mellitus (IDDM) patients with diabetic nephropathy varies considerably. Therefore, we tested the potential role of an insertion (I)/deletion (D) polymorphism of the ACE gene on this early antiproteinuric responsiveness in an observational follow-up study. Sixty (II, N = 13; ID, N = 26 and DD, N = 21) young hypertensive IDDM patients suffering from diabetic nephropathy were investigated during three months before and for the initial six month period during ACE inhibition [captopril 44 (SD 22) mg/24 hr, no differences in drug dose between groups]. Blood pressure (MABP) and albuminuria (ELISA) were measured three (1 to 6) times before and three (1 to 13) times during ACE inhibition. At baseline the groups (II/ID/DD) had comparable (1) mean arterial blood pressure (MABP mm Hg) of 113 +/- 10/108 +/- 9/114 +/- 8, (2) albuminuria (geometric mean with 95% CI) 1394 (747 to 2608)/1176 (844 to 1797) and 1261 (827 to 2017) mg/24 hr, and (3) serum creatinine (geometric mean with 95% CI), 80 (68 to 93)/85 (76 to 97)/103 (85 to 119) mumol/liter, respectively. Angiotensin converting enzyme inhibition induced a significant reduction in MABP, albuminuria and kidney function in all three groups (II/ID/DD; P < 0.05): (1) MABP (mean +/- SD) 12 +/- 7/5 +/- 7/8 +/- 9 mm Hg (ANOVA, P = 0.02); (2) albuminuria [mean (95% CI)] 61 (34 to 77)/22 (3 to 37)/31 (13 to 46) %, (ANOVA, P < 0.01); and (3) increasing serum creatinine [mean (95% CI)] 8 (4 to 12)/9 (3 to 16)/8 (0 to 16) % (ANOVA, NS), respectively. Adjusting for differences in reduction in MABP did not change the association between decrease in albuminuria and ACE/ID genotypes (P < 0.01). A multiple linear regression analysis revealed that the ACE/ID polymorphism, albuminuria and MABP at baseline independently influenced the decline in albuminuria after initiation of ACE inhibition (R2 = 0.21, P < 0.01). A significant association between changes in MABP and albuminuria was demonstrated (R2 = 0.16, P < 0.01). Our data show that hypertensive albuminuric IDDM patients with the II genotype are particularly susceptible to commonly advocated renoprotective treatment.

Adult↗
PubMed1998

Predisposition to essential hypertension and development of diabetic nephropathy in IDDM patients.

Conflicting results have been reported on the relationship between familial predisposition to hypertension and development of diabetic nephropathy in IDDM. In our case-control study, we assessed the prevalence of hypertension among parents of 73 IDDM patients with diabetic nephropathy (DN+; persistent albuminuria > 200 microg/min or > 300 mg/24 h) and 73 IDDM patients without diabetic nephropathy (DN-; urinary albumin excretion < 20 microg/min or < 30 mg/24 h). Arterial hypertension, defined as antihypertensive therapy or a 24-h ambulatory blood pressure (SpaceLabs 90207) > or = 135/85 mmHg, was present in 57% of parents of DN+ patients compared with 41% of parents of DN- patients (P = 0.034; difference 16% [95% CI 1.3-29.6%]). In addition, the cumulative incidence of hypertension was higher among parents of DN+ patients (log-rank test P < 0.001), with a shift toward younger age at onset of hypertension in this group. However, the difference in prevalence of parental hypertension was not evident using office blood pressure measurements (64 vs. 57%; NS; difference 7% [-5.8-20%). Furthermore, patients with DN+ and with antihypertensive therapy in both parents were themselves more frequently treated for hypertension than were patients with DN+ and without parental treatment for hypertension (100 vs. 61%; P = 0.034; difference 39% [21-57%]). In conclusion, familial predisposition to essential hypertension increases the risk of diabetic nephropathy and may also contribute to the development of systemic hypertension in patients with IDDM and diabetic nephropathy.

Adult↗
PubMed1998

Beneficial impact of ramipril on left ventricular hypertrophy in normotensive nonalbuminuric NIDDM patients.

OBJECTIVE: To evaluate the effect of the ACE inhibitor ramipril as compared with placebo on left ventricular mass index (LVMI) in normotensive, nonalbuminuric NIDDM patients with left ventricular hypertrophy (LVH). Patients with NIDDM are characterized by excessive cardiovascular morbidity and mortality, and LVH, an independent risk factor for cardiac events, is often present in NIDDM patients. RESEARCH DESIGN AND METHODS: A total of 38 normotensive, nonalbuminuric (albuminuria < 100 mg/24 h) NIDDM patients with LVH (LVMI > 131 g/m2 in men and > 100 g/m2 in women) were enrolled in a 6-month randomized, double-blind parallel group study to compare the effects of ramipril (5 mg/day) with placebo on LVMI (echocardiography, Vingmed CFM725, Diasonics Sonotron), QTc dispersion determined as the interlead variation in QTc interval on standard electrocardiogram (ECG), and 24-h ambulatory blood pressure (A&D TM2420, Tokyo, Japan). A total of 16 ramipril (10 men, 60 +/- 9 years [mean +/- SD]) and 15 placebo-treated (8 men, 55 +/- 10 years) patients completed the study, and their data are presented. RESULTS: Ambulatory blood pressure was almost identical at baseline (132/76 +/- 3/1 vs. 133/74 +/- 5/2 mmHg [mean +/- SEM]) and remained stable during follow-up (134/76 +/- 3/1 vs. 136/74 +/- 6/2 mmHg) in the ramipril and placebo group, respectively. LVMI was comparable at baseline (137.1 +/- 7.0 vs. 129.6 +/- 3.7 g/m2) in the ramipril and placebo group, respectively, and decreased significantly more in the ramipril group as compared with the placebo group (17.6 +/- 3.0 vs. 5.7 +/- 4.6 g/m2, respectively, 11.9 [0.7-23.1] g/m2, mean difference [95% CI]; P = 0.037). QTc dispersion was comparable at baseline (60.2 [5.5] vs. 64.1 [6.5] ms) and did not change significantly during follow-up: -2.5 [7.0] vs. -12.2 [9.5] ms; mean difference 9.8 (-14.2 to 33.8 ms) in the ramipril and placebo group, respectively. CONCLUSIONS: Ramipril induces regression of LVH in normotensive, nonalbuminuric NIDDM patients, independent of reduction in systemic blood pressure.

Aged↗
PubMed1998

Increased left ventricular mass in normotensive type 1 diabetic patients with diabetic nephropathy.

OBJECTIVE: Diabetic nephropathy increases the risk of premature cardiovascular disease and sudden death, particularly in type 1 diabetic patients. One possible mechanism for this risk may be left ventricular hypertrophy. In our study, we aimed to evaluate left ventricular structure and function in normotensive type 1 diabetic patients with and without nephropathy. RESEARCH DESIGN AND METHODS: M-mode and Doppler echocardiography was performed in 17 type 1 diabetic patients with nephropathy (albuminuria [median (range)], 345 (135-2,846) mg/24 h) and compared with 34 normotensive, normoalbuminuric (10 [3-30] mg/24 h) type 1 diabetic patients matched for arterial blood pressure (mean +/- SD) ([134/77] +/- [13/7] vs. [129/78] +/- [12/7] mmHg), age (40 +/- 11 vs. 42 +/- 10 years), duration of diabetes (28 +/- 7 vs. 28 +/- 6 years), and BMI (24.2 +/- 4.2 vs. 24.6 +/- 2.4 kg/m2). RESULTS: Left ventricular mass (LVM) index was significantly higher in patients with nephropathy compared with patients with normoalbuminuria (100.8 +/- 10.3 vs. 88.2 +/- 21.0 g/m2, respectively; P = 0.02). Greater ventricular septum width was demonstrated in the nephropathic group compared with the control group (9.4 +/- 1.0 vs. 8.2 +/- 1.3 mm, respectively; P = 0.002). No significant difference in posterior wall thickness was apparent. The nephropathic group tended to have reduced diastolic function (E/A ratio, 1.2 +/- 0.3 vs. 1.4 +/- 0.4; P = 0.09). Fractional shortening was normal and about the same in the two groups. The groups did not differ with respect to serum creatinine or hemoglobin, while metabolic control (assessed by HbA1c) and plasma renin and prorenin levels were elevated in the nephropathic group compared with the normoalbuminuric group. CONCLUSIONS: A blood pressure-independent increase in LVM may contribute to the increased cardiac morbidity and mortality in normotensive type 1 diabetic patients with diabetic nephropathy. Glycemic abnormalities and activation of the renin-angiotensin system may lead to the ventricular enlargement.

Adult↗
PubMed1997

Genetic variation of a collagen IV alpha 1-chain gene polymorphism in Danish insulin-dependent diabetes mellitus (IDDM) patients: lack of association to nephropathy and proliferative retinopathy.

In insulin-dependent (Type 1) diabetes mellitus (IDDM) the development of nephropathy is partly due to genetic susceptibility. Previously one study has demonstrated a relationship between a HindIII restriction polymorphism of the collagen IV alpha 1-chain gene and diabetic nephropathy. The aim of the present study was to evaluate such as association in a case-control study including 207 Danish IDDM patients: 116 with nephropathy (urinary albumin excretion rate (AER) > 300 mg 24 h-1) and 91 without nephropathy (AER < 30 mg 24 h-1). Using genomic DNA, HindIII restriction fragment length analysis revealed a bi allele polymorphism visualized by southern hybridization with a cDNA probe recognizing the collagen IV alpha 1-chain gene. No differences in genotype frequencies or allele frequencies were demonstrated comparing patients with and without nephropathy: p = 0.39 and p = 0.96, respectively. Neither were there any difference in genotype frequencies or allele frequencies when the patients were stratified according to the presence of proliferative retinopathy: p = 0.44 and p = 0.84, respectively. Pooling the diabetic groups revealed genotype frequencies and allele frequencies comparable to those found in 57 healthy unrelated Danish individuals. We conclude that in a Danish IDDM population a HindIII restriction polymorphism of the collagen IV alpha 1-chain gene is not associated with diabetic nephropathy, diabetic retinopathy or with diabetes per se.

Adult↗
PubMed1997

Renal protection in diabetes--an emerging role for calcium antagonists.

The combination of diabetes and hypertension increases the changes of progressive renal disorder and ultimately renal failure. Roughly 40% of all diabetics, whether insulin dependent or not, develop diabetic nephropathy. Diabetic nephropathy is the single most important cause of end-stage renal disease in the western world and accounts for more than a quarter of all end-stage renal diseases. It is also a major cause of increased morbidity and mortality in diabetic patients. Increased arterial blood pressure is an early and common phenomenon in incipient and overt diabetic nephropathy. The relationship between arterial blood pressure and diabetic nephropathy is a complex one, diabetic nephropathy increasing blood pressure and blood pressure accelerating the course of nephropathy. Calcium antagonists antagonize preglomerular vasoconstriction. Furthermore, additional putative mechanisms include the ability to retard renal growth and possibly to attenuate mesangial entrapment of macromolecules and to attenuate the mitogenic effects of diverse growth factors. Calcium antagonists (except the old short-acting dihydropyridine drugs) reduce microalbuminuria and preserve kidney function in diabetic patients with incipient diabetic nephropathy. Long-term trials using the new long-acting dihydropyridine calcium antagonists for the treatment of patients with incipient nephropathy are still lacking. A recent 1-year randomized double-blind study in hypertensive insulin-dependent diabetic patients with diabetic nephropathy showed a more beneficial effect on the decline rate in the glomerular filtration rate of nisoldipine (long-acting dihydropyridine) than angiotensin-converting-enzyme (ACE) inhibition. The mean arterial blood pressure during the study based on 24-hour recordings was nearly identical, 103 (SD 9) and 101 (SD 11) mm Hg in the two groups. Furthermore, a recent 5-year randomized open study in hypertensive noninsulin-dependent patients with diabetic nephropathy has revealed the same beneficial effect of a calcium antagonist and ACE inhibition on the progression of nephropathy. In a third group treated with sympatholytic drugs, more than 50% of the subjects had a doubling of their creatinine as compared to less than 10% in the two other groups mentioned above. However, long-term studies are needed to consolidate these findings and expand them to insulin-dependent diabetic patients with diabetic kidney disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Differences between nisoldipine and lisinopril on glomerular filtration rates and albuminuria in hypertensive IDDM patients with diabetic nephropathy during the first year of treatment.

Our objective was to compare the effect of a long-acting calcium antagonist (nisoldipine) versus an ACE inhibitor (lisinopril) on albuminuria, arterial blood pressure, and glomerular filtration rate (GFR) in hypertensive IDDM patients with diabetic nephropathy. We performed a 1-year, double-blind, double-dummy, randomized, controlled study comparing nisoldipine (20-40 mg once daily) with lisinopril (10-20 mg once daily) in 52 hypertensive IDDM subjects with diabetic nephropathy. Three patients dropped out, and results for the remaining 49 (25 nisoldipine, 24 lisinopril) are presented. Diuretics were required in 10 nisoldipine- and 8 lisinopril-treated patients. Every 3 months, 24-h ambulatory blood pressure (TM2420, A&D, Tokyo, Japan) and albuminuria in three 24-h samples (enzyme immunoassay) were measured; GFR (51Cr-EDTA plasma clearance) was recorded every 6 months. Mean arterial blood pressure (24 h) was reduced from (mean +/- SE) 108 +/- 3 mmHg at baseline to 101 +/- 2 in average during treatment in the lisinopril group and from 105 +/- 2 to 103 +/- 2 in the nisoldipine group (P = 0.06 comparing changes in the two groups). Albuminuria was reduced 47% (95% CI 21-65) in the lisinopril group versus an increase of 11% (-3 to 27) in the nisoldipine group (P = 0.001). Fractional albumin clearance was reduced 37% (95% CI 4-59%) in the lisinopril versus an increase of 35% (8-69%) in the nisoldipine group (P < 0.01). GFR decreased from 85 +/- 5 ml x min(-1) x 1.73 m(-2) to 73 +/- 5 in the lisinopril group and from 84 +/- 6 to 80 +/- 7 in the nisoldipine group (P < 0.05). The effect of study medication on albuminuria and GFR was independent of changes in systemic blood pressure and baseline variables in multiple regression analyses. In summary, lisinopril reduced albuminuria, but also GFR, to a greater extent than did nisoldipine in hypertensive IDDM patients with diabetic nephropathy during the 1st year of treatment. Longer follow-up is required to clarify whether these drugs have different renoprotective effects.

Adult↗
PubMed1996

[Low birth weight--increased risk of diabetic nephropathies?].

It has been demonstrated that intrauterine growth retardation gives rise to a reduction in nephron number. Oligonephropathy has been suggested to enhance the risk for expression of renal disease following exposure to potentially injurious renal stimuli. In a case-control study we investigated if low birth weight is a risk factor for development of diabetic nephropathy in 184 IDDM patients with diabetic nephropathy (persistent albuminuria > 300 mg/24 hours) and 182 normoalbuminuric (< 30 mg/24 hours) patients. In women with birthweight < 10 th centile (< or = 2,700 g, n = 16) 75% had nephropathy compared to only 35% among patients > 90 th centile (> or = 4,000 g, n = 17) (p = 0.05). In men with birth-weight < 10th centile (< or = 2,910 g, n = 22) the prevalence of nephropathy: 50%, was similar to the prevalence among patients > 90th centile (> or = 4,200 g, n = 24) 54%. Mean weight at birth were similar in patients with and without diabetic nephropathy. Men with diabetic nephropathy were significantly shorter than men with normoalbuminuria (176.9 (7.1) vs 179.4 (6.5), p < 0.01). In conclusion, our study supports the hypothesis that genetic predisposition or factors operating in utero or early childhood, or both, contribute to the development of diabetic nephropathy.

Adult↗
PubMed1996

Effect of deletion polymorphism of angiotensin converting enzyme gene on progression of diabetic nephropathy during inhibition of angiotensin converting enzyme: observational follow up study.

OBJECTIVE: To evaluate the concept that an insertion/deletion polymorphism of the angiotensin converting enzyme gene predicts the therapeutic efficacy of inhibition of angiotensin converting enzyme on progression of diabetic nephropathy. DESIGN: Observational follow up study of patients with insulin dependent diabetes and nephropathy who had been treated with captopril for a median of 7 years (range 3-9 years). SETTING: Outpatient diabetic clinic in a tertiary referral centre. PATIENTS: 35 patients with insulin dependent diabetes and nephropathy were investigated during captopril treatment (median 75 mg/day (range 12.5 to 150 mg/day)) that was in many cases combined with a loop diuretic, 11 patients were homozygous for the deletion allele and 24 were heterozygous or homozygous for the insertion allele of the angiotensin converting enzyme gene. MAIN OUTCOME MEASURES: Albuminuria, arterial blood pressure, and glomerular filtration rate according to insertion/deletion polymorphism. RESULTS: The two groups had comparable glomerular filtration rate, albuminuria, blood pressure, and haemoglobin A1c concentration at baseline. Captopril induced nearly the same reduction in mean blood pressure in the two groups-to 103 (SD 5) mm Hg in the group with the deletion and 102 (8) mm Hg in the group with the insertion-and in geometric mean albumin excretion-573 (antilog SE 1.3) micrograms/min and 470 (1.2) micrograms/min, respectively. The rate of decline in glomerular filtration rate (linear regression of all glomerular filtration rate measurements during antihypertensive treatment) was significantly steeper in the group homozygous for the double deletion allele than in the other group (mean 5.7 (3.7) ml/min/year and 2.6 (2.8) ml/min/year, respectively; P = 0.01). Multiple linear regression analysis showed that haemoglobin A1c concentration, albuminuria, and the double deletion genotype independently influenced the sustained rate of decline in glomerular filtration rate (R1 (adjusted) = 0.51). CONCLUSION: The deletion polymorphism in the angiotensin converting enzyme gene reduces the long term beneficial effect of angiotensin converting enzyme inhibition on the progression of diabetic nephropathy in patients with insulin dependent diabetes.

Adult↗
PubMed1996

Circadian rhythm of arterial blood pressure and albuminuria in diabetic nephropathy.

The aim of our study was to evaluate the diurnal relationship between arterial blood pressure and albuminuria, and some potential mechanisms responsible for impaired nocturnal blood pressure reduction (non-dippers, groups I and II) in diabetic nephropathy (DN). Twenty-four-hour ambulatory blood pressure, heart rate (HR) variation (autonomic nervous function) and extracellular fluid volume (ECV) were measured, and urine samples were collected three times during the corresponding day- and nighttimes in 47 insulin-dependent diabetic (IDDM) patients with DN. Mean arterial blood pressure (MABP) during the daytime [mm Hg, median (range)] was identical in group I [105 (96-137)], group II [109 (86-124)] and group III [dippers; average blood pressure reduction from day to night > 10%, 107 (93-132), P = NS], while the nighttime MABP differed [group I, 106 (95-144); group II, 100 (78-118); group III, 91 (76-118); P < 0.001]. No significant difference between the groups concerning the daytime or nighttime albuminuria [microgram/min; median (range)] was observed; [Day: group I, 1467 (235-3933); group II, 695 (170-6719); group III, 875 (228-3173). Night: group I, 1079 (279-4665); group II, 572 (113-3807); group III, 659 (81-2493)]. A significant correlation between MABP and albuminuria was demonstrated during day- (rho = 0.50, P < 0.0005) and nighttime (rho = 0.46, P < 0.005), while neither the absolute nor the relative changes in MABP from day to night correlated significantly with absolute or relative changes in albuminuria from day to night. The night/day ratio of HR was higher in group I [0.93 (0.76-1.09), median (range)] compared to group III [0.83 (0.74-1.02), P < 0.005] and a significant correlation between this ratio and the night/day ratio of MABP was found (rho = 0.54, P < 0.0005). ECV was about the same in the three groups. Our study indicated an association between blood pressure and albuminuria, but the mechanisms involved in the reduction of albuminuria from day to night was not unraveled. A relative lack of sympathetic withdrawal during sleep seems to be an important feature of nocturnal hypertension in diabetic nephropathy.

Adult↗
PubMed1996

Development of enzyme-linked immunoassays for human angiotensin I converting enzyme suitable for large-scale studies.

OBJECTIVE: To develop and validate a simple immunological assay for human angiotensin converting enzyme (ACE) based on monoclonal antibodies. METHODS: Microtitre plates were coated with mouse monoclonal antibody (MoAb) to human ACE (9B9) and incubated with diluted samples of human plasma. In the sandwich enzyme-linked immunosorbent assay (ELISA), the plasma ACE, bound to MoAb 9B9, was revealed using polyclonal anti-ACE antibodies and alkaline phosphatase conjugated to goat anti-rabbit immunoglobulin G. In the plate precipitation assay the ACE activity, quantitatively precipitated from human plasma by MoAb 9B9, was measured by enzymatic fluorimetric assay with p-benzyloxycarboxyl-glycyl-L-histidyl-L-leucine or p-benzyloxycarboxyl-L-phenylalanyl-L-histidyl-L-leucine as substrate, directly in the wells. RESULTS: These assays are specific for the amino-terminal domain of ACE and recognize differences in the conformations of native and recombinant ACE. The sensitivity of the sandwich ELISA was 200 pg/ml assay medium; it quantifies the ACE in 10 microliters human plasma or less. Intra- and inter-assay variability coefficients were 6.2 and 13.6%, respectively. Both variants of the assay determined the plasma ACE concentration in the presence of ACE inhibitors or EDTA. The ACE concentrations were determined by sandwich ELISA in a population of 138 middle-aged healthy Caucasian subjects. They were strongly correlated with the ACE gene insertion/deletion (I/D) polymorphism, which accounted for 20% of the variance of plasma ACE concentration in this population and 16-24% of the variance in plasma ACE activity as measured with three different enzymatic assays. CONCLUSION: The ACE concentration (but not inhibition) can be determined by this ELISA which is suitable for large-scale studies of plasma ACE levels.

Animals↗
PubMed1996

Renal protection in diabetes: an emerging role for calcium antagonists.

BACKGROUND: The combination of diabetes and hypertension increases the chances of progressive renal disorder and, ultimately, renal failure. Roughly 40% of all diabetics, whether insulin-dependent or not, develop diabetic nephropathy. Diabetic nephropathy is the single most important cause of end-stage renal disease in the Western world and accounts for more than a quarter of all end-stage renal diseases. Diabetic nephropathy is a major cause of increased morbidity and mortality in diabetic patients. Increased arterial blood pressure is an early and common phenomenon in incipient and overt diabetic nephropathy. The relationship between arterial blood pressure and diabetic nephropathy is a complex one, with diabetic nephropathy increasing blood pressure and blood pressure accelerating the course of nephropathy. OVERVIEW: Calcium antagonists antagonize preglomerular vasoconstriction. Additional putative mechanisms include the ability to retard renal growth and possibly to attenuate mesangial entrapment of macromolecules, and to attenuate the mitogenic effect of diverse growth factors. Calcium antagonists (except the original short-acting dihydropyridine drugs) reduce microalbuminuria and preserve kidney function in diabetic patients with incipient diabetic nephropathy. There are still no long-term trials using the new long-acting dihydropyridine calcium antagonists to treat patients with incipient nephropathy. A recent, 1-year, randomized, double-blind study in hypertensive insulin-dependent diabetic patients with diabetic nephropathy showed a better attenuation of the rate of decline in glomerular filtration in patients treated with nisoldipine (long-acting dihydropyridine) than with an angiotension converting enzyme (ACE) inhibitor. The mean 24-h arterial blood pressure during this study was almost identical in both treatment groups, at 103 (SD 9) and 101 (SD 11) mmHg, respectively. Furthermore, a recent 5-year randomized open study in hypertensive non-insulin-dependent patients with diabetic nephropathy has revealed the same beneficial effect of a calcium antagonist and of ACE inhibition on the progression of nephropathy. In a third group treated with sympatholytic drugs, creatinine levels doubled in more than 50% of the subjects compared to less than 10% in the two other groups mentioned above. However, long-term studies are needed to consolidate these findings and expand them to insulin-dependent diabetic patients with diabetic kidney disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Genetics of diabetic nephropathy.

Diabetic nephropathy is a clinical syndrome characterized by persistent albuminuria, a relentless decline in GFR, raised arterial blood pressure, and increased relative mortality for cardiovascular diseases. Diabetic nephropathy is a leading cause of end-stage renal failure. The pathogenesis of diabetic nephropathy is multifactorial, with contributions from metabolic abnormalities, hemodynamic alterations, and various growth factors and genetic factors. Epidemiologic and family studies have demonstrated that only a subset of the patients develop this complication that family clustering of nephropathy is present, and that ethnicity plays an important role in the risk of developing this kidney disease. Short stature and low birth weight are both associated with increased risk of developing diabetic nephropathy, supporting the hypothesis that genetic predisposition or factors operating in utero, in early childhood, or both contribute to the development of diabetic nephropathy. Studies elucidating phenotypic markers such as parenteral hypertension and systemic blood pressure elevation have yielded conflicting results. The contribution from elevated blood pressure only plays a minor role in the majority of the patients developing diabetic nephropathy. The majority of the studies have demonstrated increased sodium/lithium countertransport activity in insulin-dependent diabetes mellitus patients with nephropathy, whereas studies of this phenotypic marker in parents of patients with and without nephropathy have yielded conflicting results. Recently, studies of genetic markers involved in the regulation of blood pressure and levels of cardiovascular risk factors have been conducted. Several studies have demonstrated that the deletion polymorphism in the angiotensin-I-converting enzyme acts as a risk factor for cardiovascular disease in diabetic patients. However, a meta-analysis does not support the suggestion that this factor plays any role for the initiation of diabetic nephropathy. Similar negative results have been obtained in relation to polymorphisms of the genes encoding for angiotensinogen and the angiotensin II Type 1 receptor. However, studies in diabetic and non-diabetic glomerulopathies have clearly demonstrated a deleterious effect of the deletion polymorphism in the angiotensin-converting enzyme on the progression of kidney function.

Antiporters↗
PubMed1996

Angiotensinogen gene polymorphisms in IDDM patients with diabetic nephropathy.

Genotypic abnormalities of the renin-ANG system have been suggested as a risk factor for the development of diabetic nephropathy. Cleavage of angiotensinogen is the rate-limiting step in the activation of the renin-ANG system. The TT genotype of a polymorphism encoding threonine instead of methionine (M235T) has been associated not only with increased plasma angiotensinogen concentration but also with essential hypertension. In addition, a polymorphism in the angiotensinogen gene substituting methionine for threonine (T174M) has been associated with hypertension in nondiabetic populations. We studied the relationship between these polymorphisms in the angiotensinogen gene in IDDM patients with diabetic nephropathy (121 men, 74 women, age 40.9 +/- 10 years, diabetes duration 27 +/- 8 years). There was no difference in M235T genotype distribution between IDDM patients with diabetic nephropathy and those with normoalbuminuria: 73/97/25 (37/50/13%) vs. 67/95/23 (36/52/12%) had MM/MT/TT genotypes, respectively. No difference in distribution of T174M genotypes between nephropathic and normoalbuminuric IDDM patients was observed either: 148/44/1 (77/23/0.5%) vs. 141/42/2 (76/23/1%) had TT/TM/MM genotypes, respectively. In patients with nephropathy, systolic blood pressure was higher (161 +/- 22 mmHg [mean +/- SD]) in patients carrying TT genotype of the M235T angiotensinogen polymorphism as compared with patients with MM or MT genotypes (150 +/- 23 mmHg; P = 0.03). We conclude that neither the M235T nor the T174M polymorphism in the angiotensinogen gene contributes to genetic susceptibility to diabetic nephropathy in white IDDM patients, whereas the TT genotype of the M235T is associated with elevated blood pressure in patients with diabetic nephropathy.

Adult↗