Microalbuminuria and nephropathy in insulin dependent diabetes mellitus

Intron 4 polymorphism of the endothelial nitric oxide synthase eNOS gene and early microangiopathy in type 1 diabetes

Nitric oxide (NO) is an endogenous vasodilator involved in inflammatory and autoimmune response, and in the pathophysiology of diabetic vascular disease. Endothelium-derived NO is formed from L-arginine by endothelial NO synthase (eNOS), and earlier studies have provided evidence for altered NO metabolism and impaired endothelial function in diabetes, probably due to polymorphisms in eNOS gene. In the present study we investigated the association of the eNOS gene intron 4 a/b VNTR polymorphism with diabetic microangiopathy in 61 young individuals with type 1 diabetes (T1D), 35 male and 26 female, aged 5.0-29.1 (mean 15.6) years, and followed up for 3.24-11.4 (mean 7.44) years. Ten patients (16.4%) had developed microalbuminuria, three hypertension and two retinopathy. Wild-type b/b homozygosity for eNOS gene intron 4 VNTR was found in 37 (60.7%) and a/b polymorphism in 24 (39.3%). No significant relationship was demonstrated between eNOS gene intron 4 polymorphisms and microalbuminuria, hypertension or retinopathy in these young individuals. Our findings suggest that a/b polymorphism of the intron 4 eNOS gene is not associated with early onset diabetic microangiopathy.

Diabetic nephropathy in children and adolescents

Type 1 diabetes mellitus (T1DM) commonly occurs in childhood or adolescence, although the rising prevalence of type 2 diabetes mellitus (T2DM) in these age groups is now being seen worldwide. Diabetic nephropathy (DN) develops in 15-20% of subjects with T1DM and in similar or higher percentage of T2DM patients, causing increased morbidity and premature mortality. Although overt DN or kidney failure caused by either type of diabetes are very uncommon during childhood or adolescence, diabetic kidney disease in susceptible patients almost certainly begins soon after disease onset and may accelerate during adolescence, leading to microalbuminuria or incipient DN. Therefore, all diabetics warrant ongoing assessment of kidney function and screening for the earliest manifestations of renal injury. Pediatric health care professionals ought to understand about risk factors, strategy for prevention, method for screening, and treatment of early DN. This review considers each form of diabetes separately, including natural history, risk factors for development, screening for early manifestations, and strategy recommended for prevention and treatment of DN in children and adolescents.

Novel roles of the IGF-IGFBP axis in etiopathophysiology of diabetic nephropathy

Mechanisms contributing to development of diabetic nephropathy (DN) remain unclear. High ambient glucose level transforms intracellular pathways, promoting stable phenotypic changes in the glomerulus such as mesangial cell hypertrophy, podocyte apoptosis, and matrix expansion. Insulin-like growth factors (IGFs) and the high affinity IGF binding proteins (IGFBPs) exert major effects on cell growth and metabolism. Compared with diabetic patients without microalbuminuria (MA), MA diabetic patients display perturbed GH-IGF-IGFBP homeostasis, including increased circulating IGF-I and IGFBP-3 protease activity, increased excretion of bioactive GH, IGF-I, and IGFBP-3, but decreased circulating IGFBP-3 levels. In diabetic animal models, expression of IGF-I and IGFBP-1 to -4 increases in key renal tissues and glomerular ulrafiltrate. Epithelial, mesangial, and endothelial cells derived from the kidney respond to IGF-I binding with increased protein synthesis, migration, and proliferation. This article reviews classic and emerging concepts for the roles of the GH-IGF-IGFBP axis in the etiopathophysiology, treatment, and prevention of diabetic renal disease. We report IGF-independent actions of IGFBP-3 in the podocyte for the first time.

Determinants of energy expenditure in ventilated preterm infants

The purpose of this study was to determine oxygen consumption (VO2), carbon dioxide production (VCO2), and energy expenditure (EE) in a group of preterm ventilated infants during the first 3 weeks of life, and to determine the major factors that influence EE. Thirty-eight indirect calorimetry studies were performed in 18 ventilated infants with mean gestational age of 27.9 +/- 0.6 (SEM) weeks. The relationship of demographic factors, nutrient intake, and severity of illness assessments of EE were determined by regression analysis. Repeated measure analysis was performed for the effect of multiple studies in the same patient. Although VO2, VCO2, and EE all tended to increase over the first 3 weeks of life, there was a wide range of values. EE was best predicted by nonprotein calorie intake and postnatal age, while there was no correlation with birthweight, weight at the time of study, gestational age, protein intake, or severity of illness. Multiple regression analyses demonstrated a strong interaction between PNA and EI. In this population EE is best predicted by PNA and EI. The interactive effect between PNA and EI on EE is probably explained by the clinical practice of daily increments in substrate intake in these patients.

Evaluation of the components of insulin-like growth factor (IGF)-IGF binding protein (IGFBP) system in adolescents with type 1 diabetes and persistent microalbuminuria: relationship with increased urinary excretion of IGFBP-3 18 kD N-terminal fragment

OBJECTIVE

IGFs and their binding proteins (IGFBPs) have an important role in controlling glucose homeostasis and there is evidence to support their involvement in complications related to type I diabetes. The aim of this study was to evaluate the components of the IGF-IGFBP system in adolescents with type 1 diabetes that had developed persistent microalbuminuria (MA).

DESIGN AND PATIENTS

A cohort of 49 adolescents with type 1 diabetes were enrolled in the study. Patients were evaluated at baseline and 1 year later (follow-up). Twenty-six patients with persistent urinary albumin excretion (UAE) of more than 20 microg/min/1.73 m2 (21.6-109. 4 microg/min/1.73 m2) in three different nocturnal urinary collections within 6 months were considered to have MA (baseline mean: 41.9 +/- 22.3 microg/min/1.73 m2; follow-up: 55.9 +/- 24.8 microg/min/1.73 m2). Twenty-three patients with UAE of less than 20 microg/min/1.73 m2 were assigned to the group without MA (baseline mean: 8.6 +/- 3.7 microg/min/1.73 m2; follow-up: 11.8 +/- 4.2 microg/min/1.73 m2). Fasting serum levels of IGFBP-1, IGFBP-2, IGFBP-3, IGF-I and free-IGF-I were determined using appropriate immunoenzymatic, radioimmuno- or immunoradiometric assays. Overnight 12-h urinary collections were obtained and assessed for IGFBP-3 levels, determined by immunoradiometric assay. Urinary and circulating immunoreactive IGFBP-3 forms were determined by Western-immunoblotting (WIB) analysis using a specific polyclonal antibody and monoclonal antibodies directed against N-terminal and C-terminal epitopes of IGFBP-3. IGFBP-3 protease activity was determined using protease assay and by analysis of the intact over the fragmented immunoreactive forms of IGFBP-3 determined by WIB analysis.

RESULTS

Patients with MA showed higher levels of urinary IGFBP-3 (649 +/- 440 ng/h/m2) than patients without MA (398 +/- 229 ng/h/m2; P < 0.05). Urinary levels of IGFBP-3 were directly correlated to UAE (P < 0.001). WIB analysis, using monoclonal antibodies directed against characterized N-terminal and C-terminal IGFBP-3 epitopes, determined that the immunoreactive form of IGFBP-3 found in urine from patients with diabetes was an N-terminal 18 kD fragment. Serum IGFBP-3 levels were lower in patients with MA (baseline: 3613 +/- 598 microg/l; one year follow-up: 3347 +/- 624 microg/l) compared with patients without MA (baseline: 4701 +/- 1484 microg/l; follow-up: 4177 +/- 703 microg/l; P < 0.001). In serum from patients with MA, intact IGFBP-3 was decreased, as indicated by WIB analysis. Conversely, IGFBP-3 proteolysis was increased in patients with MA (baseline: 131 +/- 21% of control; follow-up: 130 +/- 23% of control), compared to patients with normal UAE (baseline: 96 +/- 23% of control; follow-up: 96 +/- 14% of control; P < 0.001). Serum IGFBP-3 protease activity was directly correlated to urinary IGFBP-3 levels (P < 0.001). Serum IGFBP-1 levels were increased in patients with MA (baseline: 36 +/- 20 microg/l; follow-up: 36 +/- 17 microg/l) compared with patients without MA (baseline: 17 +/- 11 microg/l; follow-up: 18 +/- microg/l; P < 0.05). Serum IGFBP-2 levels were also persistently increased in patients with MA (baseline: 503 +/- 134 microg/l; follow-up: 484 +/- 166 microg/l) compared with patients without MA (baseline: 375 +/- 83 microg/l; follow-up: 390 +/- 85 microg/l; P < 0.05). On the other hand, free IGF-I levels were decreased in patients with MA (baseline: 2.3 +/- 1. 5 microg/l; follow-up: 2.5 +/- 1. (ABSTRACT TRUNCATED)

Characterization of fatty acid clearance in premature neonates during intralipid infusion

This study reports the clearance of plasma triglyceride and phospholipid fatty acids during Intralipid 20% infusion (Pharmacia, Sweden) in nine ventilated preterm infants receiving parenteral nutrition. Blood samples were taken during lipid infusion and over a subsequent period of 36 h of fat-free parenteral nutrition. Plasma triglyceride fatty acids showed a uniform and rapid decline after lipid was stopped from the peak values recorded during infusion. In contrast, plasma phospholipid fatty acids showed a variable decline during fat-free nutrition. This variability appeared to be the result of a differing contribution of infused egg yolk phospholipid fatty acids to the measured plasma values, and to changing fatty acid composition of endogenous phospholipid in response to fat free nutrition. Red cell phospholipid fatty acid composition was stable over the 36-h clearance study period. These results indicate the complexity of interpretation of plasma fatty acids during lipid infusion. We conclude that red cell phospholipid fatty acids provide the only stable measure of tissue fatty acid composition in parenterally fed preterm infants.

Sepsis during total parenteral nutrition: exploration of risk factors and determination of the effectiveness of peripherally inserted central venous catheters

BACKGROUND

Sepsis is the most frequent serious complication during total parenteral nutrition (TPN), resulting in increased morbidity, mortality and health care costs. Existing reports have not documented the risk factors of sepsis during TPN. The objectives of this study were to determine the rate of sepsis in our practice and to explore the risk factors for sepsis during TPN. We also determined the role and efficacy of using peripherally inserted central venous catheters (PCVC) as insertion catheters to administer TPN.

METHODS

From October, 1994, to May, 1996, we administered TPN to 378 pediatric patients hospitalized at Mackay Memorial Hospital. We followed all cases for the occurrences of any complications while administering TPN. We studied all patients who had fever, a clinical presentation of sepsis and a positive blood culture during their course of TPN.

RESULTS

During the 20-month period 378 patients received TPN for a total of 6562 days. Fifty-six patients presented with clinical sepsis and positive blood cultures. Significant features in the sepsis group included longer duration of TPN, age < 3 months, usage of central venous catheters, gastrointestinal diseases as indication for TPN, low birth weight and short gestational age in prematurity. Seven patients died despite prompt antimicrobial therapy. One hundred eleven patients received TPN via PCVC for a mean duration of 17.1 days, significantly longer than 10.4 days in the peripheral intravenous catheter group but no difference between the sepsis rates.

CONCLUSION

Considering the high incidence of sepsis during TPN, every attempt should be made to minimize the length of TPN therapy and encourage early enteral feeding. We also recommend the use of PCVC in patients requiring prolonged nutritional support.

Early onset of diabetic nephropathy

A 12 year old Asian girl with a four year history of poorly controlled insulin dependent diabetes mellitus developed overt diabetic nephropathy. There were no clinical features of Rabson-Mendenhall syndrome. Screening for microalbuminuria would have identified incipient diabetic nephropathy and highlighted the importance of good glycaemic control. Although screening for microalbuminuria is recommended after five years from diagnosis, it may be appropriate to undertake this annually in those with poor glycaemic control.