Molecular heterogeneity in fetal forms of type II lissencephaly

Type II lissencephaly (type II LIS) is a group of autosomal recessive congenital muscular dystrophies (CMD) associated with defects in alpha-DG O-glycosylation, which comprises Walker-Warburg syndrome, Fukuyama cerebral and muscular dystrophy, or muscle-eye-brain disease. The most severe forms of these diseases often have a fetal presentation and lead to a pregnancy termination. We report here the first molecular study on fetal type II LIS in a series of 47 fetuses from 41 unrelated families. Sequencing of the different genes known to be involved in alpha-DG O-glycosylation allowed the molecular diagnosis in 22 families: involvement of POMT1 was demonstrated in 32% of cases, whereas POMGNT1 and POMT2 were incriminated in 15% and in 7% of cases, respectively. We found 30 different mutations in these three genes, 25 were described herein for the first time, 15 in POMT1, and five in POMT2 and POMGNT1. Despite sequencing of FKRP, FCMD, and LARGE, no definitive molecular diagnosis could be made for the other half of our cases. Preliminary results concerning genotype-phenotype correlations show that the choice of the first gene sequenced should depend on the clinical severity of the type II LIS; POMT1 and POMT2 for severest clinical picture and POMGNT1 for milder disease. The other genes, FKRP, FCMD, and LARGE, seem not to be implicated in the fetal form of CMD.     

The complete genome sequence of Lactobacillus bulgaricus reveals extensive and ongoing reductive evolution

Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) is a representative of the group of lactic acid-producing bacteria, mainly known for its worldwide application in yogurt production. The genome sequence of this bacterium has been determined and shows the signs of ongoing specialization, with a substantial number of pseudogenes and incomplete metabolic pathways and relatively few regulatory functions. Several unique features of the L. bulgaricus genome support the hypothesis that the genome is in a phase of rapid evolution. (i) Exceptionally high numbers of rRNA and tRNA genes with regard to genome size may indicate that the L. bulgaricus genome has known a recent phase of important size reduction, in agreement with the observed high frequency of gene inactivation and elimination; (ii) a much higher GC content at codon position 3 than expected on the basis of the overall GC content suggests that the composition of the genome is evolving toward a higher GC content; and (iii) the presence of a 47.5-kbp inverted repeat in the replication termination region, an extremely rare feature in bacterial genomes, may be interpreted as a transient stage in genome evolution. The results indicate the adaptation of L. bulgaricus from a plant-associated habitat to the stable protein and lactose-rich milk environment through the loss of superfluous functions and protocooperation with Streptococcus thermophilus.     

Should PMM2-deficiency (CDG Ia) be searched in every case of unexplained hydrops fetalis?

Hydrops fetalis (HF) is characterized by an accumulation of fluid in the extracellular compartments and in body cavities. Non-immune HF (NIHF) is caused by a wide variety of disorders and overall, 20–25% of NIHF remain unexplained. Inborn errors of metabolism, mostly lysosomal storage diseases have been estimated to account for 1–2% of cases, leading to HF by anemia or liver failure. Very few cases of NIHF and Congenital Disorder of Glycosylation (CDG) have been reported. We present here a case of recurrence of HF in a non-related couple in which the diagnosis of CDG type I was suspected at fetal pathological examination then confirmed at the enzymatic and molecular levels, as well as on a characteristic CDG I serum transferrin profile at 30 weeks of gestation. We also provide a systematic review of reported cases with CDG type I and NIHF reported thus far. When NIHF remains unexplained despite exhaustive obstetrical screening, analysis of PMM activity in the parents' leucocytes is possible and might be performed easily during pregnancy. The accurate diagnosis is important in terms of counseling during pregnancy or later, in order to allow an early molecular prenatal diagnosis for the following pregnancies.     

Inter- and intra-tumoral heterogeneity in DNA damage evaluated by comet assay in early breast cancer patients

There are no clinical tools to functionally assess degree of DNA damage in breast cancer. The comet assay is an accepted research tool for assessing DNA damage, however, most cancer studies have assessed lymphocytes as surrogate cells. The aim of this pilot study was to use the comet assay in early breast cancer directly in tumor tissue to compare DNA damage between and within traditionally defined subgroups, and to explore intra-tumoral heterogeneity. Scrapings of tumor and healthy breast tissue were obtained at primary surgery from 104 women. Comet assay was applied to quantitatively assess DNA damage, revealing substantial inter- and intra-subgroup variation. Marked intra-tumoral heterogeneity was evident across all subgroups. The degree of DNA damage for an individual could not be predicted by breast cancer subgroup. Comet assay warrants further study as a potential clinical tool for identification of tumoral DNA damage and ultimately, individualised use of DNA damaging therapy.     

Prognostic value of troponins in sepsis: a meta-analysis

Rationale

The role of biomarkers such as troponin in risk stratification of sepsis is still debated. The aim of this meta-analysis is to assess the relation between troponin elevation in sepsis and mortality.

Methods

All observational studies from Embase, Medline and those manually searched up to September 2010 were included. Studies identified were those which reported on patients with a diagnosis of sepsis and if a 2 × 2 table could be constructed based on troponins and death. We pooled the relative risk (RR) and odds-ratio (OR) using the inverse variance method in studies that conducted univariate and multivariable (adjusted) analysis.

Main results

Thirteen studies encompassing 1,227 patients were included. The prevalence of elevated troponin was 61 % ([95 %] CI 58–64 %). Elevated troponin was significantly associated with all-cause mortality (RR 1.91; CI 1.63–2.24), with homogeneity across studies. In adjusted analysis (four studies comprising 791 patients) according to prognostic scores, elevated troponin was associated with an increased risk of death (OR 1.92; CI 1.35–2.74). The area under the ROC curve was 0.68 (CI 0.63–0.71). Pooled sensitivity and specificity were 77 % (CI 61–88) and 47 % (CI 30–64) with heterogeneity across studies. It corresponded to positive and negative likelihood ratios of 1.50 (95 % CI: 1.20–1.90) and 0.49 (CI 0.38–0.64), respectively.

Conclusions

Elevated troponin identifies a subset of patients with sepsis at higher risk of death. Further studies are needed to define the precise role of troponins and their optimal cut-offs.     

Hypometabolism exceeds atrophy in presymptomatic early-onset familial Alzheimer's disease.

The aim of the present study is to compare brain atrophy with hypometabolism as preclinical markers of Alzheimer's disease (AD) by studying presymptomatic individuals from families with known early-onset autosomal dominant AD (FAD) carrying mutations in the Presenilin 1 gene. METHODS: Seven asymptomatic at-risk FAD individuals (age, 35-49 y; 4 women; education >/= 12 y) and 7 matched healthy control subjects received complete clinical, neuropsychologic, MRI, and (18)F-FDG PET examinations. Regions of interest (ROIs: whole brain [WB], hippocampus [Hip], entorhinal cortex [EC], posterior cingulate cortex [PCC], inferior parietal lobule [IPL], and superior temporal gyrus (STG]) were drawn on the MRI scans of all subjects and used to measure volumes on MRI and glucose metabolism (MRglc) from the MRI-coregistered, atrophy-corrected PET scans. RESULTS: Compared with controls and after correcting for head size, MRI volume reductions in FAD subjects were restricted to the IPL (18%, P < 0.02). After atrophy correction and adjusting for pons MRglc, PET MRglc reductions were found in all FAD subjects compared with controls in the WB (13%), bilaterally in the IPL (17%) and in the STG (12%), and in the left EC (21%), PCC (20%), and Hip (12%) (P values < 0.05). PET MRglc measurements were consistently less variable than MRI measures, yielding significantly larger effect sizes in separating FAD from controls. CONCLUSION: Presymptomatic FAD individuals show widespread MRglc reductions consistent with the typical AD PET pattern in the relative absence of structural brain atrophy. These data further suggest that PET MRglc measures may serve as biomarkers for the preclinical diagnosis of AD.     

Comparison between two amplification sets for molecular diagnosis of toxoplasmosis by real-time PCR

PCR is now commonly applied to the diagnosis of toxoplasmosis. Although several methods are available, comparative studies are few, making it difficult to compare the performance of each technique. We compared the sensitivities of two real-time PCR assays through a prospective study on fetuses, neonates, and immunocompromised patients and on the ocular diagnosis of toxoplasmosis. The first system targeted the widely used B1 gene (GenBank accession number AF179871) while the second (RE) targeted a more recently described sequence repeated roughly 200 to 300 times (GenBank accession number AF146527). We demonstrated that molecular diagnosis requires the duplication of PCR assays, especially with the B1 system, as only one PCR was positive in 33.3% of cases. Our study showed that the RE target was more sensitive for all biological samples (amniotic fluid, placenta, aqueous humor, whole blood, and cerebrospinal and bronchoalveolar fluids) and significantly improved the performance of the diagnosis of toxoplasmosis. Taking into consideration all clinical samples, the mean gain in the crossing point value was 4.2 +/- 1.7 cycles and was even more significant for amniotic fluid (5.8 +/- 1.7 cycles).     

The dual role of cognitive reserve in subjective cognitive decline and mild cognitive impairment: a 7-year follow-up study

Journal of Neurology - The aim of this study was to evaluate the effect of cognitive reserve (CR), in progression from subjective cognitive decline (SCD) to mild cognitive impairment (MCI) and...