Anna Körner

Increased Renal Metabolism in Diabetes: Mechanism and Functional Implications

The coupling between the Na+/glucose cotransporter and Na+-K+-ATPase (NKA) described for epithelial cells (1) prompted us to study in rats with streptozocin-induced diabetes the effect of increased tubular glucose load on tubular Na+ reabsorption, NKA-dependent O2 consumption (QO2), and NKA activity. Filtered glucose is mainly reabsorbed in the proximal tubuli via the phlorizin-sensitive Na+/glucose cotransporter. In this study, the diabetic rats had a significantly higher renal blood flow (RBF), glomerular filtration rate (GFR), and Na+ reabsorption than the control rats. Total renal QO2 as well as QO2 in cortical tissue, which consists mainly of proximal tubular cells, was significantly higher in diabetic than in control rats. The increase in tissue QO2 was entirely caused by increased NKA-dependent QO2. NKA activity, measured as rate of ATP hydrolysis, was increased in cortical tubular but not glomerular tissue from diabetic rats. Phlorizin treatment abolished the increase in NKA activity, Na+ reabsorption, and QO2, as well as the increase in RBF and GFR in diabetic rats. We conclude that diabetes is associated with increased renal O2 metabolism secondary to the increase in coupled Na+ reabsorption via the Na+/glucose cotransporter and NKA. The increased oxygen consumption might contribute to the hyperperfusion and hyperfiltration in the diabetic kidney.

Frequencies of genetic polymorphisms of TLR4 and CD14 and of HLA-DQ genotypes in children with celiac disease, type 1 diabetes mellitus, or both

Objectives: Besides the central role of the adaptive immune system, a disturbance of innate immunity is also involved in the pathogenesis of celiac disease (CD). Inasmuch as CD and type 1 diabetes mellitus (T1DM) frequently coexist because of a common genetic predisposition, our aim was to study the frequency of CD14 C-260T and TLR4 A+896G single nucleotide polymorphisms (SNPs) and the distribution of HLA-DQ genotypes in children affected by CD, T1DM, or both. Patients and Methods: TLR4 and CD14 SNPs were tested by polymerase chain reaction, followed by restriction fragment length polymorphism analysis in 80 children with T1DM, 100 children with CD, and 47 children with both CD and T1DM. Determination of HLA-DQ alleles was done by sequence-specific polymerase chain reaction. Frequencies were compared with those of healthy control children. Results: The prevalence of the homozygous CD14 C-260TT genotype was significantly (P = 0.0081) lower in children with T1DM but not in those with CD and T1DM, compared with control children. No difference was found in the genotype and allele frequencies of TLR4 between the studied groups. In patients with T1DM, the frequency of the homozygous HLA-DQ8 genotype was significantly higher than in CD, whereas the frequency of homozygous or heterozygous HLA-DQ2 genotypes did not differ from that in control children. In patients with CD, both homozygous and heterozygous HLA-DQ2 genotypes were significantly more frequent than in the control and T1DM groups, and no elevation in the frequency of the HLA-DQ8 genotypes was observed. In patients with T1DM and those with CD and T1DM, the occurrence of HLA-DQ2/8 heterozygosity was significantly higher than in children with CD only and in control children. Conclusions: Our results suggest that in patients with T1DM, the CD14 C-260TT homozygous genotype increases the risk for the development of CD. The distribution of HLA-DQ genotype is different in children with CD and T1DM than in children with CD or T1DM only. Determination of the HLA-DQ genotype in children with T1DM may help in estimating the risk for the development of CD.

Changes in plasma and urinary amino acid levels during diabetic ketoacidosis in children

Plasma and urinary concentrations of different amino acids were investigated during diabetic ketoacidosis (DKA) and 12, 24, 72 hours after initiation of therapy. In DKA, plasma concentration of glutamic acid, aspartic acid, valine, leucine and isoleucine significantly increased while that of asparagine and glutamine decreased compared to levels in well-controlled diabetic patients. The urinary excretion of branched-chain amino acids, histidine, serine and threonine was elevated while those of glutamic acid, glutamine, glycine and taurine were reduced. Among the different amino acids, histidine excretion had the highest variability. A strong correlation was found between the urinary excretion of several amino acids and that of the beta-2-microglobulin characterizing tubular dysfunction. Changes in the excretion of different amino acids reflect the altered metabolic state and renal function due to DKA.

Rapid development of glomerulosclerosis in diabetic Dahl salt-sensitive rats

Summary Diabetic nephropathy tends to develop more readily in patients with a family history of hypertension and/or disturbances in sodium transport across the plasma membrane. This prompted us to study the renal effects of diabetes mellitus in a rat strain which is predisposed to develop salt-sensitive hypertension, the Dahl salt-sensitive rat. Diabetes is associated with several aberrations in the renal handling of sodium, such as elevation of tubular Na+, K+ATPase activity. This effect was more pronounced in Dahl salt-sensitive than in Dahl salt-resistant rats. Severe renal lesions, characteristic of the advanced phase of diabetic nephropathy are very rarely observed in rats with streptozotocin diabetes. However, 2 months after induction of diabetes, the Dahl salt-sensitive rats had morphological signs of advanced glomerular disease. The urinary albumin concentration was very high, but did not correlate with the blood pressure. Non-diabetic Dahl salt-sensitive rats as well as Dahl salt-resistant diabetic and non-diabetic rats had little or no signs of glomerular disease and consistently very low urinary albumin concentrations. [Diabetologia (1997) 40: 367–373]

Association between G−308A polymorphism of the tumor necrosis factor‐α gene and 24‐hour ambulatory blood pressure values in type 1 diabetic adolescents

Krikovszky D, V´s´rhelyi B, Tóth‐Heyn P, Körner A, Tulassay T, Madácsy L. Association between G−308A polymorphism of the tumor necrosis factor‐α gene and 24‐hour ambulatory blood pressure values in type 1 diabetic adolescents. 
Clin Genet 2002: 62: 474–477.

Genetic polymorphism of interleukin-1β is associated with risk of type 1 diabetes mellitus in children

Type 1 diabetes mellitus (T1DM) is an auto-immune disease characterised by the selective destruction of pancreatic b-cells. The events that trigger b-cell damage have remained elusive: however, the importance of local inflammatory processes has been established. Interleukin-1 (IL-1) is a crucial cytokine causing b-cell inhibition. Screening of a number of available cytokine preparations at relevant concentrations showed that no other single cytokine had similar effects on intact rat islets and IL-1 alone is cytotoxic to human pancreatic islet cells in monolayer cultures [2]. The biological activity of IL-1 resided in two major polypeptide species, called interleukin-1alpha (IL-1a) and interleukin-1beta (IL-1b). IL-1b plays a central role in b-cell dysfunction and death [1, 2]. The production of IL-1b is, at least partly determined by the C3954T polymorphism in exon 5 of the IL-1b gene. The carrier state of the 3954T allele is associated with enhanced cytokine production [5]. Limited data are available about its impact on the risk of T1DM [5, 6]. Therefore in our investigation the association between IL-1b C3954T polymorphism and T1DM was studied. Blood samples were taken from 312 children with T1DM (162 boys and 150 girls, mean age: 14±4 years, mean duration of diabetes: 6.3±3.7 years). The healthy reference population consisted of 171 healthy blood donors. Total genomic DNA was extracted from whole blood using the method of Miller et al. [3]. IL-1b C3954T polymorphism was determined by PCR and RFLP methods as previously described [4]. PCR products were digested at 65 C with TaqI. The products were separated in a 3% agarose gel, stained with ethidium bromide and visualised under UV illumination. The study was approved by the Institutional Ethics Committee and informed consent was obtained from the subjects and/or their parents. Allele-frequencies were compared using the chi-squared test. The Mann-Whitney test was used for the comparison of the age at the onset of T1DM between patients with different genotypes. Hardy-Weinberg criteria were fulfilled in the healthy reference population, but not in diabetic children. The prevalence of the 3954T allele was higher among children with T1DM than the healthy reference group (0.34 versus 0.26; P=0.0002; Odds Ratio =2.02, 95% confidence interval: 1.384–2.950) (Table 1). The age at the onset of T1DM was not associated with IL-1b genotype. This study is the first that investigates the importance of IL1-b C3954T polymorphism in a relatively large number of diabetic children. Our results indicate that the 3954T carrier state might be associated with the risk of T1DM. We suggest that when b-cells are exposed to harmful events, 3954T allele carrier children respond with elevated IL-1b production. This higher level of IL1b might play a role in the maintenance of auto-immune damage of pancreatic b-cells and contribute to the development of T1DM. Eur J Pediatr (2002) 161: 507–508 DOI 10.1007/s00431-002-1030-9

Severe Hyperinsulinemic Hypoglycemia in a Neonate: Response to Sirolimus Therapy

Hyperinsulinemic hypoglycemia (HH) is one of the most common causes of persistent hypoglycemic episodes in neonates. Current pharmacologic treatment of neonatal HH includes diazoxide and octreotide, whereas for diffuse, unresponsive cases a subtotal pancreatectomy may be the last resort, with questionable efficacy. Here we report a case of congenital diffuse neonatal HH, first suspected when severe hypoglycemia presented with extremely high serum insulin levels immediately after birth. Functional imaging and genetic tests later confirmed the diagnosis. Failure to respond to a sequence of different treatments and to avoid extensive surgery with predictable morbidity prompted us to introduce a recently suggested alternative therapy with sirolimus, a mammalian target of rapamycin inhibitor. Glucose intake could be reduced gradually while euglycemia was maintained, and we were able to achieve exclusively enteral feeding within 6 weeks. Sirolimus was found to be effective and well tolerated, with no major adverse side effects attributable to its administration.

Pajzsmirigy- autoimmunitás elofordulása 1-es típusú diabéteszes gyermekekben

UNLABELLED It is well known that patients suffering from an autoimmune disease are more prone to develop another one, too. The authors have previously shown frequent occurrence of celiac disease in patients with type 1 diabetes mellitus compared to the background population. Autoimmune thyroid disease, the most common autoimmune disease associated with type 1 diabetes mellitus, generally occurs after the manifestation of diabetes, in the second decade of life. The aim of the study was to investigate the prevalence of thyroid autoimmunity as well as the frequency of autoimmune thyroid disease in patients with type 1 diabetes mellitus. Their aim was also to compare the prevalence of autoimmune thyroid disease in patients with type 1 diabetes mellitus and in those with type 1 diabetes mellitus and celiac disease. METHODS Screening was performed in 268 patients with type 1 diabetes mellitus alone and in 48 children with type 1 diabetes mellitus and celiac disease, with anti-peroxidase and anti thyroglobulin antibody. In case of autoantibody positivity, testing thyroid function and ultrasonography confirmed the autoimmune thyroid disease. According to the results, frequency of autoantibody positivity was significantly higher in diabetic patients suffering from celiac disease (type 1 diabetes mellitus: 43 (16%), type 1 diabetes mellitus + celiac disease: 16 (33,3%), p < 0,01). Hypothyroidism due to thyroiditis was also more prevalent in patients with type 1 diabetes mellitus and celiac disease. CONCLUSIONS Due to increased risk, the authors emphasise the need of frequent screening for autoimmune thyroid disorder in patients with type 1 diabetes mellitus and celiac disease.

Sympathetic-Adrenergic Activity and Acid-Base Regulation under Acute Physical Stress in Type I (Insulin-Dependent) Diabetic Children

To evaluate the efficacy of the acute-physical-stress response, plasma catecholamine and lactate levels, serum electrolytes, fructosamine, blood glucose and acid-base status were measured in insulin-dependent diabetes mellitus (IDDM) children and the data compared to those of healthy controls. Four groups were studied: group 1, healthy controls; group 2, newly diagnosed diabetic patients with an IDDM duration of 2-4 weeks; group 3, with an IDDM duration of 5-7 years; group 4, with an IDDM duration of 10-13 years. According to their fructosamine levels, IDDM children were in a well-controlled metabolic state. The physical stress was induced by 1.5-1.7 W/kg/10 min bicycle ergometer determined by a target pulse rate of 170/min. IDDM children exhibited pronounced lactic acidosis under stress (pH: group 2, 7.27 +/- 0.07; group 3, 7.28 +/- 0.05; group 4, 7.20 +/- 0.04, vs. group 1; 7.34 +/- 0.03). Baseline plasma norepinephrine and epinephrine levels showed a significant decrease parallel to the duration of IDDM. Stress induced an increase in the concentration of norepinephrine in each group, but the elevation was significantly higher in the IDDM children versus the controls. A significant negative correlation was found between pH and maximal plasma norepinephrine levels (y = 7.3-0.006x, r = -0.46, p < 0.02). Stress resulted in blood glucose elevation in 13 patients regardless of their pre-exercise blood glucose levels.(ABSTRACT TRUNCATED AT 250 WORDS)

PPAR-γ2 Pro12Ala polymorphism is associated with post-challenge abnormalities of glucose homeostasis in children and adolescents with obesity

Abstract Aim: The aim of the study was to investigate the association between PPAR-γ2 Pro12Ala polymorphism and laboratory characteristics of carbohydrate metabolism in children and adolescents with obesity. In addition, serum levels of tumor necrosis factor (TNF)-α, and soluble form of its receptors (sTNFR1 and sTNFR2) were assessed. Methods: In a cross-sectional study, 79 obese children and adolescents of Caucasian origin were investigated. PPAR-γ2 Pro12Ala polymorphism was determined using polymerase chain reaction – restriction fragment length polymorphism technique. Serum levels of TNF-α, sTNFR1 and sTNFR2 were measured by enzyme amplified sensitivity immunoassay. Results: The minor Ala allele frequency was found to be 14.56% in our cohort. No significant differences in age, BMI, waist circumference, blood pressure, serum lipid, uric acid, TNF-α, sTNFR1 and sTNFR2 values were found between carriers of the Ala allele (Pro/Ala and Ala/Ala; n=21) vs. homozygous carriers of the Pro allele (Pro/Pro; n=58). However, post-challenge (120 min) plasma glucose and insulin values were significantly lower in Ala allele carriers vs. homozygous Pro allele carriers (6.56±0.26 vs. 7.36±0.25 mmol/L and 65.9±13.8 vs. 111.8±20.7 μU/mL, respectively; p<0.05); while no significant differences were found at fasting state. Conclusions: The association between PPAR-γ2 Pro12Ala polymorphism and glucose metabolism is already present in children and adolescents with obesity who might be at the very beginning of the natural course of type 2 diabetes. At this stage, higher insulin sensitivity can be detected in Ala allele carriers compared to homozygous Pro subjects at post-challenge but not in fasting state; however, the TNF-system seems not to be involved in the alteration of glucose homeostasis due to PPAR-γ2 Pro12Ala polymorphism.