Urine π-Glutathione S-transferase but not Tamm-Horsfall protein correlates with carotid artery intima media thickness in childhood type1 diabetes.

BACKGROUND: Renal disease remains a serious threat in patients with insulin-dependent (type1) diabetes. Hence its detection early in the life of patients with type1 diabetes is crucial. Several lines of evidence suggest similar mechanisms for the development of both renal and arterial disease. We sought to investigate in young patients with type1 diabetes whether π-Glutathione S-transferase to creatinine (π-GST:crea) and Tamm-Horsfall protein to creatinine (THP:crea) ratios, markers of distal tubular renal function, relate to subclinical markers of arterial disease, which appear to onset early and develop rapidly in type1 diabetes. METHODS: Seventy-one children and adolescents (median age and diabetes duration 14 and 6 years, respectively) with type1 diabetes for at least 6 months were assessed for timed urine levels of π-GST, THP, HbA1c, albumin, and plasma C-reactive protein (CRP). Carotid artery intima-media thickness (IMT), brachial artery flow-mediated dilatation (FMD), and cutaneous microvascular function were assessed by high-resolution ultrasound and laser Doppler, respectively. RESULTS: Two patients had microalbuminuria (> 20 µg/min), and were therefore removed from the study population. π-GST:crea ratio and THP:crea showed no relationship to the demographic, diabetes, or inflammatory indices. Lower π-GST:crea ratio was associated with greater IMT (p = 0.01, r = -0.29), particularly in female patients (p = 0.004, r = -0.49). The association of π-GST:crea ratio with IMT was stronger in patients with passive smoke exposure (p = 0.002, r = -0.43). Among post-pubertal patients, lower π-GST:crea ratio was also associated with lower microvascular response to Ach (acetylcholine; p = 0.03, r = 0.49). CONCLUSIONS: In young patients with type1 diabetes, proximal tubular dysfunction as suggested by lower levels of π-GST:crea ratio seems to be paralleled by changes in arterial structure and microvascular function.

Intermittent maple syrup urine disease: two case reports.

The presenting symptoms and clinical course of 2 cases of intermittent maple syrup urine disease (MSUD) are described. Intermittent MSUD is a potentially life-threatening metabolic disorder caused by a deficiency of branched-chain α-keto acid dehydrogenase, the enzyme complex that decarboxylates the 3 branched-chain amino acids. In contrast to classic MSUD, children with the intermittent form show normal development with normal intelligence and, when asymptomatic, normal levels of branched-chain amino acids. Symptoms usually appear between 5 months and 2 years of age, when a trivial infection such as otitis media or viral gastroenteritis triggers catabolism of muscle protein. Intermittent MSUD should be suspected in cases of common infections with a clinically atypical course, especially in children displaying ataxia or marked drowsiness.

Urine α-Glutathione S-transferase, systemic inflammation and arterial function in juvenile type 1 diabetes.

BACKGROUND: Despite marked improvement in therapy and monitoring of patients with insulin-dependent (type 1) diabetes, diabetic nephropathy remains a serious complication, with subsequent end-stage renal disease in about 20% of cases. OBJECTIVE: To investigate in young patients with type 1 diabetes whether urine α-Glutathione S-transferase to creatinine ratio (α-GST:crea) relates to markers of systemic inflammation and subclinical vasculopathy. DESIGN: Children and adolescents (median age and diabetes duration 14 and 6 years, respectively) with type 1 diabetes screened in a previous study for proximal tubular (urine α-GST:crea ratio) and renal (plasma creatinine, cystatin C glomerular filtration rate (GFR), and timed urine albumin excretion rate (AER)) function were, within the same timeframe, also investigated for vascular (blood pressure, carotid artery intima-media thickness (IMT) and compliance (CAC), brachial artery flow-mediated dilatation (FMD) and plasma cyclic guanosine monophosphate (cGMP) and inflammatory (C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α)) profiles. Exposure to environmental tobacco smoke (ETS) was assessed through questionnaire (n=67 respondents). RESULTS: None of the patients (n=69) had overt renal insufficiency. AER correlated with age (p=0.01, r=0.3), diabetes duration (p=0.02, r=0.3), FMD (p=0.04, r=-0.3, n=52), CAC (p=0.03, r=-0.3, n=62) and cGMP (p=0.01, r=-0.3, n=59). α-GST:crea was lower (p=0.03) in patients than in controls. α-GST:crea appeared to be particularly lower in older patients (p=0.004, r=-0.34 vs age), in those with worse diabetic control (p=0.03, r=-0.26 vs HbA1c), and in those with lower carotid artery elasticity (p=0.017, r=0.3 vs CAC). Although ETS had no direct significant impact on α-GST:crea, α-GST:crea correlated with FMD only in patients with ETS (r=0.5, p=0.009, n=13). α-GST:crea showed positive association with TNF-α (p=0.01, r=0.3). CONCLUSION: In children and adolescents with type 1 diabetes, lower levels of urine excretion of α-GST:crea appear to be associated with decreasing elasticity and endothelial vasomotor function of peripheral arteries, especially in patients with ETS. In contrast, higher levels of α-GST:crea are more common in patients with elevated markers of systemic inflammation. Large scale prospective studies are needed to clarify the meaning and mechanisms of this association.

Comparing binding site information to binding affinity reveals that Crp/DNA complexes have several distinct binding conformers.

We show that the cAMP receptor protein (Crp) binds to DNA as several different conformers. This situation has precluded discovering a high correlation between any sequence property and binding affinity for proteins that bend DNA. Experimentally quantified affinities of Synechocystis sp. PCC 6803 cAMP receptor protein (SyCrp1), the Escherichia coli Crp (EcCrp, also CAP) and DNA were analyzed to mathematically describe, and make human-readable, the relationship of DNA sequence and binding affinity in a given system. Here, sequence logos and weight matrices were built to model SyCrp1 binding sequences. Comparing the weight matrix model to binding affinity revealed several distinct binding conformations. These Crp/DNA conformations were asymmetrical (non-palindromic).

Illumination stimulates cAMP receptor protein-dependent transcriptional activation from regulatory regions containing class I and class II promoter elements in Synechocystis sp. PCC 6803.

The cAMP receptor protein (Crp) is a global transcriptional regulator that binds sequence-specific promoter elements when associated with cAMP. In the motile cyanobacterium Synechocystis sp. strain PCC 6803, intracellular cAMP increases when dark-adapted cells are illuminated. Previous work has established that Crp binds proposed Crp target sites upstream of slr1351 (murF), sll1874 (chlA(II)), sll1708 (narL), slr0442 and sll1268 in vitro, and that slr0442 is downregulated in a crp mutant during photoautotrophic growth. To identify additional Crp target genes in Synechocystis, 11 different Crp binding sites proposed during a previous computational survey were tested for in vitro sequence-specific binding and crp-dependent transcription. The results indicate that murF, chlA(II) and slr0442 can be added as 'target genes of Sycrp1' in Synechocystis. Promoter mapping of the targets revealed the same close association of RNA polymerase and Crp as that found in Escherichia coli class I and class II Crp-regulated promoters, thereby strongly suggesting similar mechanisms of transcriptional activation.

Urinary transforming growth factor-beta(1), collagen IV and the effect of insulin in children at diagnosis of diabetes mellitus.

OBJECTIVE: This study investigated whether metabolic derangement at diagnosis of diabetes mellitus affects the function of the basement membrane and the excretion of several components and whether insulin treatment can normalize this. It was designed to evaluate urinary excretion rates of transforming growth factor-beta(1) (TGF-beta(1)), the carboxy-terminal domain of collagen IV (NC1) and albumin in children during the first 20 days of treatment after diagnosis of type 1 diabetes. MATERIAL AND METHODS: Thirty-four newly diagnosed diabetic children between 4 and 16 years of age and 26 healthy children of matching age were studied with timed overnight urine collections. Urine was collected during the first 20 days of treatment. RESULTS: Urinary excretion of albumin and TGF-beta(1) in diabetic children were significantly increased at entry but normalized during 20 days of treatment with insulin compared with control children. In contrast, the non-significant high NC1 excretion at diagnosis did not change but became significantly increased after 20 days of insulin treatment. Overall, the kidney size was within normal limits and unaffected by treatment. The largest kidneys had less NC1 excretion (R= - 0.67, p<0.05, n=13) and a lower glomerular filtration rate (R= - 0.77, p<0.01, n=10) than the smallest kidneys. After 20 days of treatment TGF-beta(1) excretion had decreased in children with kidney size > 8.5 cm. CONCLUSION: Correction of the metabolic derangement with insulin decreased excretion of albumin and TGF-beta(1), but had no effect on kidney size and urine NC1 excretion, presumably because the observation period was too short.

Tubular function in diabetic children assessed by Tamm-Horsfall protein and glutathione S-transferase.

In a previous study, we found urinary excretion of Tamm-Horsfall protein (THP) to be persistently decreased in 25% of patients during the first year after diagnosis of diabetes mellitus. We thus wanted to study another marker for distal tubular function, pi glutathione S-transferase (pi-GST) and compare this and THP with proximal tubular function evaluated with alpha-GST and alpha-1-microglobulin (HC) in patients with longer duration of diabetes. One hundred and eighty-four diabetic and 16 control children were studied with timed overnight urine collections. Median age was 14 years, and median age at diagnosis was 8 years. The urinary excretion of alpha- and pi-GST was significant lower in diabetic than control children. There were no differences in the excretion of HC and THP. Diabetic children with decreased alpha-GST had higher albumin excretion, HbA 1c levels, and longer diabetes duration but decreased THP excretion and cystatin-C clearance compared with those with normal excretion. In contrast, a decreased pi-GST or THP excretion was not associated with such differences. Diabetic children with increased HC excretion had increased HbA 1c levels. Diabetic children, before the stage of microalbuminuria, may have signs of both proximal and distal tubular dysfunction, which is related to diabetes duration and poor metabolic control. Alpha-GST and pi-GST seem to be more sensitive than other parameters studied.

Pore size and charge selectivity of the glomerular membrane at the time of diagnosis of diabetes.

The urinary albumin excretion rate is increased at the time of diagnosis of diabetes. We investigated whether this is caused by change in pore size or charge selectivity in the glomerular basement membrane. Urine excretion of immunoglobulins (IgG2, IgG4), glycosaminoglycans (GAG), and albumin was analyzed during the first 20 days after diagnosis of diabetes in children aged 4-15 years; 36 diabetic and 24 age-matched apparently healthy children were included. The excretion of albumin was significantly increased on day 1 in the diabetic children. Between day 1 and 20 the excretion of IgG2 and IgG4 decreased significantly from normal to a level below normal. GAG excretion was not affected. The GAG/creatinine index (GAGCI) was normal. IgG2CI was significantly below normal on days 4-20. IgG4CI was below normal on days 2-20. The albumin creatinine index decreased significantly from day 1 to normal levels on day 4-20. A charge selectivity index, expressed as the ratio between the neutrally charged IgG2 and the negatively charged IgG4, was significantly below the normal level on days 16 and 20. In conclusion, an increased albumin excretion rate in urine did not seem to be caused by a change in charge selectivity. Other explanations such as change in the small pore radius or tubular reabsorption are suggested.

Metabolic status in diabetes mellitus affects markers for glomerular filtration rate.

The present study was performed in newly diagnosed diabetic children to evaluate the effect of metabolic derangement on routine tests for glomerular filtration rate (GFR). Children with ( n=16) and without ( n=10) ketonuria at diagnosis of diabetes followed a routine clinical treatment program. Serum creatinine, creatinine clearance, serum cystatin C, and iohexol clearance were analyzed at diagnosis and after 20 days of treatment. Iohexol clearance was used as the "true GFR". Serum creatinine and iohexol clearances were not affected by the acute metabolic status or ketonuria. In contrast, serum cystatin C was significantly influenced by ketonuria. Creatinine clearance was an unreliable marker for GFR both in the more deranged and in the balanced metabolic situation.