Use of the omp50 gene for identification of Campylobacter species by PCR

We studied the prevalence of the omp50 gene and the Omp50 protein in Campylobacter strains. Immunodetection assays and DNA-DNA hybridizations showed that most C. coli strains tested were negative and most C. jejuni and C. lari strains tested were positive. A PCR assay was developed, using the omp50 gene as a species-specific target. We propose a combination of a hippurate test and an omp50 assay to perform identification of Campylobacter species.     

Neu–Laxova syndrome presenting prenatally with increased nuchal translucency and cystic hygroma: The utility of exome sequencing in deciphering the diagnosis

Neu–Laxova syndrome (NLS) is a lethal autosomal recessive microcephaly syndrome associated with intrauterine growth restriction (IUGR) and multiple congenital anomalies. Clinical features include central nervous system malformations, joint contractures, ichthyosis, edema, and dysmorphic facial features. Biallelic pathogenic variants in either the PHGDH or PSAT1 genes have been shown to cause NLS. Using exome sequencing, we aimed to identify the underlying genetic diagnosis in three fetuses (from one family) with prenatal skin edema, severe IUGR, micrognathia, renal anomalies, and arthrogryposis and identified a homozygous c.1A>C (p.Met1?, NM_006623.3) variant in the PHGDH gene. Loss of the translation start codon is a novel genetic mechanism for the development of NLS. Prenatal diagnosis of NLS is challenging and few reports describe the fetal pathology. Fetal neuropathologic examination revealed: delayed brain development, congenital agenesis of the corticospinal tracts, and hypoplasia of the hippocampus, cerebellum and brainstem. Each pregnancy also showed increased nuchal translucency (NT) or cystic hygroma. While NLS is rare, it may be a cause of recurrent increased NT/cystic hygroma. This finding provides further support that cystic hygroma has many different genetic causes and that exome sequencing may shed light on the underlying genetic diagnoses in this group of prenatal patients.     

Shear Rate Dependence of Ultrasound Backscattering from Blood Samples Characterized by Different Levels of Erythrocyte Aggregation

The objectives were (1) to determine the effect of the erythrocyte aggregation level (wide range of aggregation) and shear rate (which also affects aggregation) on the ultrasound backscattered power, and (2) to evaluate the reproducibility of the ultrasound method. Experiments were performed under steady flow (100–1250 ml/min) in a 12.7 mm diameter vertical tube. Doppler ultrasound at 10 MHz was used to measure simultaneously the velocity and the backscattered power across the tube. For each radial position, the shear rate was computed from the derivative of the velocity profile. The backscattered power decayed exponentially as a function of the shear rate, and for a given shear rate, the power increased monotonically with the level of aggregation measured by laser reflectometry. Using blood samples simulating hypo-, normal, and hyperaggregating erythrocytes, the power of the ultrasound signal varied respectively by –7.8, –13.2, and –16.1 dB as a function of the shear rate (from 0.4 to 50 s^–1). The reproducibility of the backscattered power was 5.5 dB, which is less than the variations observed as a function of the shear rate. In conclusion, ultrasound backscattering is sensitive to the level of erythrocyte aggregation. At a first glance, ultrasound seems less accurate when compared to laser reflectometry but it is suggested that this is because ultrasound backscattering may be sensitive to structural aggregate changes that are not detected by the laser method. © 2000 Biomedical Engineering Society. PAC00: 8718-h, 8719Tt, 8750Kk     

β-Adrenergic and muscarinic receptor mRNA accumulation in the sinoatrial node area of adult and senescent rat hearts

The sinoatrial (SA) node is the cardiac pacemaker and changes in its adrenergic-muscarinic phenotype have been postulated as a determinant of age-associated modifications in heart rate variability. To address this question, right atria were microdissected, the SA node area was identified by acetylcholinesterase staining, and, using a RT-PCR method, the accumulation of mRNA molecules encoding β₁- and β₂-adrenergic (β₁- and β₂-AR) and muscarinic (M₂-R) receptor was quantified to define the proportion between β-AR and M₂-R mRNAs within the sinoatrial area of adult (3 months) and senescent (24 months) individual rat hearts. In adult hearts, the highest M₂-R/β-AR mRNA ratio was observed within the sinoatrial area compared with adjacent atrial myocardium, while in the senescent hearts, no difference was observed between sinoatrial and adjacent areas. This change was specific of the sinoatrial area since adult and senescent whole atrial or ventricular myocardium did not differ in their M₂-R/β-AR mRNA ratio, and was associated with a fragmentation of acetylcholinesterase staining of the senescent SA node. Quantitative changes in the expression of genes encoding proteins involved in heart rate regulation specifically affect the sinoatrial area of the senescent heart.     

Molecular cloning and expression of an anti-idiotype antibody mimicking a protective oligosaccharide of the parasite Schistosoma mansoni

Genes encoding the heavy and light chains of an anti-idiotype antibody (AB2) mimicking a protective oligosaccharide of Schistosoma mansoni were cloned and expressed as a single-chain Fv fragment. The expression in a functional state was tested using the AB1. A specific binding between sFv and AB1 was observed. Immunization with the recombinant AB2 indicates its capacity to elicit anti-S. mansoni antibodies. Received: 28 April 1997 / Accepted: 24 June 1997     

Correlation between genotype,metabolic data,and clinical presentation in carnitine palmitoyltransferase 2 (CPT2) deficiency

Carnitine palmitoyltransferase 2 (CPT2) deficiency, the most common inherited disease of the mitochondrial long-chain fatty acid (LCFA) oxidation, may result in distinct clinical phenotypes, namely a mild adult muscular form and a severe hepatocardiomuscular disease with an onset in the neonatal period or in infancy. In order to understand the mechanisms underlying the difference in severity between these phenotypes, we analyzed a cohort of 20 CPT2-deficient patients being affected either with the infantile (seven patients) or the adult onset form of the disease (13 patients). Using a combination of direct sequencing and denaturing gradient gel electrophoresis, 13 CPT2 mutations were identified, including five novel ones, namely: 371G>A (R124Q), 437A>C (N146T), 481C>T (R161W), 983A>G (D328G), and 1823G>C (D608H). After updating the spectrum of CPT2 mutations (n=39) and genotypes (n=38) as well as their consequences on CPT2 activity and LCFA oxidation, it appears that both the type and location of CPT2 mutations and one or several additional genetic factors to be identified would modulate the LCFA flux and therefore the severity of the disease.     

Hyperpipecolic acidaemia: a diagnostic tool for peroxisomal disorders

Peroxisomal disorders include a complex spectrum of diseases, characterized by a high heterogeneity from both the clinical and the biochemical points of view. Specific assays are required for the study of peroxisome metabolism. Among these, pipecolic acid evaluation is considered as a supplementary test. We have established the diagnostic role of pipecolic acid in 30 patients affected by a peroxisomal defect (5 Zellweger syndromes, 10 Infantile Refsum diseases, 1 neonatal adrenoleukodystrophy, 6 patients affected by a peroxisomal biogenesis disorder with unclassified phenotype, 1 case of rhizomelic chondrodysplasia punctata (RCDP), 2 acyl-CoA oxidase deficiencies, 2 bifunctional enzyme deficiencies, 2 Refsum diseases, and 1 beta-oxidation deficiency). Pipecolic acid was increased in all generalized peroxisomal disorders, while normal pipecolic acid with abnormal very long chain fatty acid concentrations was strong evidence for a single peroxisomal enzyme deficiency. Unexpectedly, hyperpipecolic acidaemia was found also in a child affected by RCDP and in two patients with Refsum disease. In six patients the suggestion of a peroxisomal disorder was raised by the fortuitous finding of a pipecolic acid peak in amino acid chromatography, routinely performed as a general metabolic screening. For all patients, pipecolic acid proved to be a useful parameter in the biochemical classification of peroxisomal disorders.