WT1 is a key regulator of podocyte function: reduced expression levels cause crescentic glomerulonephritis and mesangial sclerosis

Glomerular disease is one of the most common causes of end-stage renal failure. Increasing evidence suggests that these glomerulopathies are frequently caused by primary lesions in the renal podocytes. One of the major consequences of podocyte lesions is the accumulation of mesangial matrix in the glomerular basement membrane, a process called glomerulosclerosis. Mesangial sclerosis is one of the most consistent findings in Denys-Drash patients and can be caused by dominant mutations in the Wilms' tumor 1 gene (WT1). The underlying mechanism, however, is poorly understood. WT1 is expressed in the podocytes throughout life, but its function in this cell type is unknown. Combining Wt1-knockout and inducible yeast artificial chromosome transgenic mouse models, we demonstrate that reduced expression levels of WT1 result in either crescentic glomerulonephritis or mesangial sclerosis depending on the gene dosage. Strikingly, the two podocyte-specific genes nphs1 and podocalyxin are dramatically downregulated in mice with decreased levels of Wt1, suggesting that these two genes act downstream of Wt1. Taken together, our data provide genetic evidence that reduced levels of Wt1 are responsible for the pathogenesis of two distinct renal diseases and offer a molecular explanation for the increased occurrence of glomerulosclerosis in patients with WAGR syndrome.     

<Emphasis Type="Italic">TCF7L2</Emphasis>variant genotypes and type 2 diabetes risk in Brazil: significant association,but not a significant tool for risk stratification in the general population

Background  

Genetic polymorphisms of the TCF7L2 gene are strongly associated with large increments in type 2 diabetes risk in different populations worldwide. In this study, we aimed to confirm the effect of the TCF7L2 polymorphism rs7903146 on diabetes risk in a Brazilian population and to assess the use of this genetic marker in improving diabetes risk prediction in the general population.     

Critical stages of tumor growth regulation in transgenic mice harboring a hepatocellular carcinoma revealed by distinct patterns of tumor necrosis factor-alpha and transforming growth factor-beta mRNA production

There is now good evidence that cytokines contribute to the regulation of tumor growth. The cytokine-driven modulation of tumor growth was investigated during the progression of a hepatocellular carcinoma (HCC) in SV40 large T tumor antigen transgenic mice. In vivo, an increased rate of liver growth correlated with increased transforming growth factor (TGF)-beta 1 mRNA expression, while the greatest amounts of tumor necrosis factor (TNF)-alpha mRNA were detected earlier during tumor development. Conversely, no particular alteration of IL-1 alpha, IL-1 beta, IL-6, IL-2, IL-4 and IFN-gamma mRNA production could be reported. In vitro, hepatocyte-like tumor cell lines established at two stages, either before or after HCC differentiation, were characterized. The early-stage-derived cell line produced TNF-alpha mRNA, but had barely detectable expression of TGF-beta 1 mRNA, while later-stage- derived cell lines showed the reciprocal pattern. All cell lines displayed a lack of sensitivity to TNF-alpha, although some degree of sensitivity to TNF-alpha could be observed in the presence of actinomycin-D or after treatment with IFN-gamma. The early-stage- derived cell line was sensitive to the growth inhibitory effects of TGF- beta 1, but late-stage-derived tumor cell lines displayed a loss of sensitivity to TGF-beta 1 which correlated with the increased expression of TGF-beta 1 mRNA. Altogether, this suggests that tumor cells contribute to the discrete TNF-alpha and TGF-beta 1 expression patterns during HCC progression. This model of HCC could be of valuable interest to assess the impact of various immunotherapeutic strategies on modulation of tumor growth.      

Symptomatic peripheral arterial disease: the value of a validated questionnaire and a clinical decision rule

BACKGROUND: If a validated questionnaire, when applied to patients reporting with symptoms of intermittent claudication, could adequately discriminate between those with and without peripheral arterial disease, GPs could avoid the diagnostic measurement of the ankle brachial index. AIM: To investigate the Edinburgh Claudication Questionnaire (ECQ) in general practice and to develop a clinical decision rule based on risk factors to enable GPs to easily assess the likelihood of peripheral arterial disease. DESIGN OF STUDY: An observational study. SETTING: General practice in The Netherlands. METHOD: This observational study included patients of > or =55 years visiting their GP for symptoms suggestive of intermittent claudication or with one risk factor. The ECQ and the ankle brachial index were performed. The prevalence of peripheral arterial disease, defined as an ankle brachial index <0.9, was related to risk factors using logistic regression analyses, on which a clinical decision rule was developed and related to the presence of peripheral arterial disease. RESULTS: Of the 4790 included patients visiting their GP with symptoms suggestive of intermittent claudication, 4527 were eligible for analyses. The prevalence of peripheral arterial disease in this group was 48.3%. The sensitivity of the ECQ was only 56.2%. The prevalence of peripheral arterial disease in a clinical decision rule that included age, male sex, smoking, hypertension, hypercholesterolemia, and a positive ECQ, increased from 14% in the lowest to 76% in the highest category. CONCLUSION: This study indicates that the ECQ alone has an inadequate diagnostic value in detecting patients with peripheral arterial disease. The ankle brachial index should be performed to diagnose peripheral arterial disease in patients with complaints suggestive of intermittent claudication, although our clinical decision rule could help to differentiate between extremely high and lower prevalence of peripheral arterial disease.     

Oxidative stress and sleep apnoea in clinically healthy infants in the first year of life

Summary Question of the study   Respiratory instability as well as tissue damage by free radicals (oxidative stress) have been hypothesized to play a role in cases of sudden and unexpected infant death in the first year of life. The ratio of the oxidized/reduced form of redox compounds in the circulation could be used as a marker of oxidative stress. Therefore, the sleep apnoea rate and redox status of coenzyme Q10 (CoQ10) (percentage of the oxidized form in total CoQ10) were measured in a population of clinically healthy infants in their first year of life in order to study whether a physiological parameter of respiratory instability is related to a biochemical parameter of oxidative stress. Patients and methods   Between May and December 1999, 323 infants in the first year of life were referred to a paediatric sleep laboratory. Sleep apnoea rate, periodic breathing and parameters of oxygenation (SaO₂ and TcPO₂) were calculated based on polysomnographic recordings. The CoQ10 redox status was calculated based on high-pressure liquid chromatographic (HPLC) analysis. Results   Statistical analysis showed an age-dependent decrease in apnoea rate ( r = – 0.38) and CoQ10 redox status ( r = – 0.40). An increased CoQ10 redox status (median: 16.6 %; range: 7.3 – 29.7 %) was found in infants with high apnoea rates above the 90^th percentile of a reference group in comparison with infants with apnoea rates below the 90^th percentile of a reference group (median: 10.4 %; range: 5.1 – 20.4 %; P = 0.031). Conclusions   These findings may indicate that high apnoea rates are accompanied by increased formation of free radicals in clinically healthy infants in the first year of life.     

Mutational analysis of the SOX9 gene in campomelic dysplasia and autosomal sex reversal: lack of genotype/phenotype correlations

It has previously been shown that, in the heterozygous state, mutations in the SOX9 gene cause campomelic dysplasia (CD) and the often associated autosomal XY sex reversal. In 12 CD patients, 10 novel mutations and one recurrent mutation were characterized in one SOX9 allele each, and in one case, no mutation was found. Four missense mutations are all located within the high mobility group (HMG) domain. They either reduce or abolish the DNA-binding ability of the mutant SOX9 proteins. Among the five nonsense and three frameshift mutations identified, two leave the C-terminal transactivation (TA) domain encompassing residues 402-509 of SOX9 partly or almost completely intact. When tested in cell transfection experiments, the recurrent nonsense mutation Y440X, found in two patients who survived for four and more than 9 years, respectively, exhibits some residual transactivation ability. In contrast, a frameshift mutation extending the protein by 70 residues at codon 507, found in a patient who died shortly after birth, showed no transactivation. This is apparently due to instability of the mutant SOX9 protein as demonstrated by Western blotting. Amino acid substitutions and nonsense mutations are found in patients with and without XY sex reversal, indicating that sex reversal in CD is subject to variable penetrance. Finally, none of 18 female patients with XY gonadal dysgenesis (Swyer syndrome) showed an altered SOX9 banding pattern in SSCP assays, providing evidence that SOX9 mutations do not usually result in XY sex reversal without skeletal malformations.      

Somatic symptoms,pain, catastrophizing and the association with disability among children with heritable connective tissue disorders

The aim of the present study was to investigate the nature and prevalence of nonspecific somatic symptoms, pain and catastrophizing in children with Heritable Connective Tissue Disorders (HCTD), and to determine their association with disability. This observational, multicenter study included 127 children, aged 4–18 years, with Marfan syndrome (MFS) (59%), Loeys-Dietz syndrome (LDS) (8%), Ehlers-Danlos syndromes (EDS) (12%) and hypermobile Ehlers-Danlos syndrome (hEDS) (23%). The assessments included the Children's Somatization Inventory or parent proxy (CSI, PCSI), pain visual-analogue scale (VAS), SUPERKIDZ body diagram, Pain Catastrophizing Scale Child or parent proxy (PCS-C, PCS-P) and Childhood Health Assessment Questionnaire (CHAQ-30). Data from children aged ≥8 years were compared to normative data. In children ≥ 8 years (n = 90), pain was present in 59%, with a median of 4 (IQR = 3–9) pain areas. Compared to normative data, the HCTD group reported significantly higher on the CSI (p ≤ 0.001, d = 0.85), VAS pain intensity (p ≤ 0.001, d = 1.22) and CHAQ-30 (p ≤ 0.001, d = 1.16) and lower on the PCS-C (p = 0.017, d = −0.82) and PCS-P (p ≤ 0.001, d = −0.49). The intensity of nonspecific somatic symptoms and pain explained 45% of the variance in disability (r² = 0.45 F(2,48) = 19.70, p ≤ 0.001). In children ≤ 7 years (n = 37), pain was present in 35% with a median of 5(IQR = 1–13) pain areas. The mean(SD) VAS scores for pain intensity was 1.5(2.9). Functional disability was moderately correlated to the number of pain areas (r = 0.56, p ≤ 0.001), intensity of nonspecific somatic symptoms (r = 0.63, p ≤ 0.001) and pain (r = 0.83, p ≤ 0.001). In conclusion, this study supports the need for comprehensive assessment of nonspecific somatic symptoms, pain, and disability in children with HCTD to allow tailored treatment.