Search

Pyruvate dehydrogenase complex (PDHC) deficiency is a major cause of congenital lactic acidemia in children. PDHC catalyzes the thiamine-dependent decarboxylation of pyruvate. Thiamine treatment was effective for some patients with PDHC deficiency. We reexamined 30 patients with congenital lactic acidemia of unknown origin who had normal PDHC activity in their cultured fibroblasts using a routine assay with a high (0.4 mM) thiamine pyrophosphate (TPP) concentration. We measured the activity of PDHC in the presence of a low (1x10(-4) mM) TPP concentration, and analyzed for mutations in the E1alpha subunit gene. Three males had low PDHC activity in the presence of 1x10(-4) mM TPP. The DNA sequence of these three patients' X-linked E1alpha subunit revealed a substitution of alanine for valine at position 71 (V71A) in exon 3, phenylalanine for cysteine at position 101 (C101F) in exon 4, and glycine for arginine at position 263 (R263G) in exon 8, respectively. Thiamine treatment was effective in these three patients. Therefore, they had a thiamine-responsive PDHC deficiency due to a point mutation in the E1alpha subunit gene. PDHC activity should be measured at a low TPP concentration to detect thiamine-responsive PDHC deficiency so that thiamine treatment can be initiated as soon as possible.

Type II citrullinaemia (CTLN2) is an adult- or late childhood-onset liver disease characterized by a liver-specific defect in argininosuccinate synthetase protein. The enzyme abnormality is caused by deficiency of the protein citrin, which is encoded by the SLC25A 13 gene. Until now, however, few cases with SLC25A13 mutations have been reported in children with liver disease. We describe an infant who presented with neonatal hepatitis in association with hypergalactosaemia detected by neonatal mass screening. DNA analysis of SLC25A13 revealed that the patient was homozygous for a IVS11+1GA mutation. This case suggests that SLC25A13 mutant should be suspected in neonatal patients with hypergalactosaemia of unknown cause.

Overexpression of α 1 β 1 integrin directly affects rat mesangial cell behavior. Background Glomerular mesangial cell (MC) proliferation, hypertrophy, and abnormal matrix remodeling characterized by increased expression of fibronectin, laminin and collagen type IV, and neoexpression of collagen I and III are the main biological features of progressive glomerulonephritis (GN). Especially, persistent pathological matrix remodeling may lead to glomerular scar formation (glomerular scarring). We reported recently that α 1 β 1 integrin, a major collagen receptor for MCs, may be a potential adhesion molecule for MC-mediated pathological collagen matrix remodeling in GN. Methods To address further the direct role of α 1 β 1 integrin in MC behavior, such as cell growth and matrix remodeling, α 1 β 1 integrin was overexpressed in MCs by transfecting an expression vector containing a full-length rat α 1 integrin cDNA. Flow cytometry and immunoprecipitation analysis were applied for selection of transfectants with a stable expression of the α 1 integrin subunit. The effect of α 1 β 1 integrin overexpression on MC biology was examined with a 3 H-thymidine incorporation assay, flow cytometric analysis of cell size and DNA content, Western blot analysis of a cyclin-dependent-kinase inhibitor, p27 Kip1 , α-smooth muscle actin expression, and a collagen gel contraction assay. Results The α 1 transfectants displayed a dramatic inhibition of 3 H-thymidine incorporation as compared with the mock transfectants. Increased expression of the α 1 subunit inversely correlated with cell cycle progression and paralleled the expression of p27 Kip1 and α-smooth muscle actin, as well as the cell size in MCs. In addition, the α 1 -transfectants were able to enhance collagen matrix reorganization effectively. Conclusion These results indicate that MC-α 1 β 1 integrin expression is a critical determinant of MC phenotypes, including cell growth, cell size, and collagen matrix remodeling ability, and thereby contributes to scar matrix remodeling (sclerosis) in GN.

The airway can become obstructed as a result of compression by an elongated aortic arch. In this study we evaluated tracheal compression using multidetector-row CT in patients with congenital heart disease and an elongated aortic arch. The trachea was measured at the level of the aortic arch in 205 children and young adults and then the severity of tracheal compression was determined by measuring the tracheal diameter ratio (short axis diameter/long axis diameter). Patients were divided as follows: group I (normal aortic arch; n=166), group II (transversely running aortic arch; n=22), and group III (elongated aortic arch; n=17). From the viewpoint of the relationship of the great arteries, group II had D-malposition, and group III had L-malposition. Age, height, weight and body surface area were significantly correlated with the short and long axis diameter in group I. There was a negative correlation between tracheal diameter ratio and the physical size parameters. The tracheal diameter ratio in group III was 0.50±0.13, which was significantly lower than in groups I and II (P

Compression of the spinal cord due to atlantoaxial subluxation was diagnosed in a patient with Morquio's syndrome and in another with spondyloepiphyseal dysplasia (SED) congenita by cervical radiography and magnetic resonance imaging (MRI). The patient with Morquio's syndrome, a 15 year old boy, had no neurologic symptoms and his somatosensory evoked potential (SSEP) was normal. However, MRI demonstrated spinal cord compression at C1-C2. In contrast, the patient with SED congenita, an 11 year old girl, had neck pain, hyperreflexia and loss of vibration sense in both legs. These findings were explained by the absence of P3 and later waves in SSEP and by compression of the spinal cord observed on MRI. Both SSEP and MRI should be used for evaluating disorders in which atlantoaxial subluxation might be present.

The human pyruvate dehydrogenase complex (PDHC) catalyzes the thiamine-dependent decarboxylation of pyruvate. Thiamine treatment is very effective for some patients with PDHC deficiency. Among these patients, five mutations of the pyruvate dehydrogenase (E1)alpha subunit have been reported previously: H44R, R88S, G89S, R263G, and V389fs. All five mutations are in a region outside the thiamine pyrophosphate (TPP)-binding region of the E1alpha subunit. We report the biochemical and molecular analysis of two patients with clinically thiamine-responsive lactic acidemia. The PDHC activity was assayed using two different concentrations of TPP. These two patients displayed very low PDHC activity in the presence of a low (1 x 10(-4) mM) TPP concentration, but their PDHC activity significantly increased at a high (0.4 mM) TPP concentration. Therefore, the PDHC deficiency in these two patients was due to a decreased affinity of PDHC for TPP. Treatment of both patients with thiamine resulted in a reduction in the serum lactate concentration and clinical improvement, suggesting that these two patients have a thiamine-responsive PDHC deficiency. The DNA sequence of these two male patients' X-linked E1alpha subunit revealed a point mutation (F205L and L216F) within the TPP-binding region in exon 7.