Increased in vitro platelet aggregation in hypertriglyceridemias

Platelet aggregation induced by ADP and collagen was monitored in 25 patients with increased serum levels of triglycerides (7 HLPs type IIb, 14 type IV, 4 type V patients) and compared with a group of 10 normolipidaemic control persons. Platelet aggregation was studied simultaneously in platelet rich plasma (PRP) by both turbidometric and impedance technique and also in whole blood (WB) by the impedance method. Whereas platelet aggregation testing by turbidometry was limited by the optical density of the plasma samples in hypertriglyceridemia, the aggregation process could easily be registered in PRP and WB using the impedance method. Threshold aggregatory concentrations with both agonists were significantly lower for all three groups of HLP.     

Linkage studies and mutation analysis of the PDEB gene in 23 families with Leber congenital amaurosis.

The phenotype in the rd mouse is similar to the clinical presentation of Leber congenital amaurosis (LCA) in humans. Recently a nonsense mutation in the beta subunit of the cGMP phosphodiesterase (Pdeb) gene has been defined as the cause for the rd phenotype in the mouse and has raised the question as to whether mutations in the human PDEB gene might cause LCA. We have previously cloned and characterized the human homologue of the mouse Pdeb gene and have mapped it to chromosome 4p16.3. In this study, a total of 23 LCA families of various ethnic backgrounds have been investigated. Linkage analysis using highly polymorphic (CA)n microsatellites has excluded the PDEB gene as a cause for LCA in 6 families. In the remaining 17 families, we have searched for mutations in the 22 exons of the PDEB gene using single-strand gel electrophoresis (SSGE). Multiple exonic polymorphisms have been determined. However, no DNA changes in the PDEB gene have been identified in our study population which could be causative for the LCA phenotype.     

Dual Exposure to Sevoflurane Improves Anesthetic Preconditioning in Intact Hearts

Background: Anesthetic preconditioning (APC) with sevoflurane reduces myocardial ischemia-reperfusion injury. The authors tested whether two brief exposures to sevoflurane would lead to a better preconditioning state than would a single longer exposure and whether dual exposure to a lower (L) concentration of sevoflurane would achieve an outcome similar to that associated with a single exposure to a higher (H) concentration.

Methods: Langendorff-prepared guinea pig hearts were exposed to 0.4 mm sevoflurane once for 15 min (H1-15; n = 8) or 0.4 mm (H2-5; n = 8) or 0.2 mm sevoflurane (L2-5; n = 8) twice for 5 min, with a 5-min washout period interspersed. Sevoflurane was then washed out for 20 min before 30 min of global no-flow ischemia and 120 min of reperfusion. Control hearts (n = 8) were not subjected to APC. Left ventricular pressure was measured isovolumetrically. Ventricular infarct size was determined by tetrazolium staining and cumulative planimetry. Values are expressed as mean +/- SD.

Results: The authors found a better functional return and a lesser percentage of infarction on reperfusion in H2-5 (28 +/- 9%) than in H1-15 (36 +/- 8%; P < 0.05), L2-5 (43 +/- 6%; P < 0.05), or control hearts (52 +/- 7%; P < 0.05).     

Detection of Parkin (PARK2) and DJ1 (PARK7) mutations in early-onset Parkinson disease: Parkin mutation frequency depends on ethnic origin of patients

Mutations in the Parkin (PARK2) and the DJ1 (PARK7) gene cause early-onset Parkinson disease (EOPD). We tested 75 Serbian EOPD patients for mutations in both genes by conventional mutational screening (SSCP/dHPLC/sequencing) to detect small sequence alterations and by gene dosage studies (quantitative PCR) to reveal deletions or multiplications of one or more exons. A compound heterozygous Parkin mutation (exon deletion and point mutation; [c.836_972del]+[c.1411C>T]; +1 is first nucleotide of GenBank AB009973.1) was identified in a patient who showed a relatively benign course after a disease onset at 41 years. Another case had a heterozygous exon deletion in DJ1 ([c.253_322del]+[?]) and presented with an age at onset of 45 years and a rapid disease course. In conclusion, Parkin mutations are surprisingly rare in our Serbian EOPD sample, suggesting that the mutation rate depends on the ethnic origin of the patients. Although DJ1 mutations appear to be rare, we confirm their role in EOPD and demonstrate the importance of gene dosage studies.     

CAG repeat length in RAI1 is associated with age at onset variability in spinocerebellar ataxia type 2 (SCA2)

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant disorder caused by the expansion of a polymorphic (CAG)(n) tract, which is translated into an expanded polyglutamine tract in the ataxin-2 protein. Although repeat length and age at disease onset are inversely related, approximately 50% of the age at onset variance in SCA2 remains unexplained. Other familial factors have been proposed to account for at least part of this remaining variance in the polyglutamine dis-orders. The ability of polyglutamine tracts to interact with each other, as well as the presence of intra-nuclear inclusions in other polyglutamine disorders, led us to hypothesize that other CAG-containing proteins may interact with expanded ataxin-2 and affect the rate of protein accumulation, and thus influence age at onset. To test this hypothesis, we used step-wise multiple linear regression to examine 10 CAG-containing genes for possible influences on SCA2 age at onset. One locus, RAI1, contributed an additional 4.1% of the variance in SCA2 age at onset after accounting for the effect of the SCA2 expanded repeat. This locus was further studied in SCA3/Machado-Joseph disease (MJD), but did not have an effect on SCA3/MJD age at onset. This result implicates RAI1 as a possible contributor to SCA2 neurodegeneration and raises the possibility that other CAG-containing proteins may play a role in the pathogenesis of other polyglutamine disorders.     

Activated protein C resistance shows an association with pregnancy-induced hypertension

A common mutation in the factor V gene, the Leiden mutation, is the most frequent genetic cause of resistance to activated protein C (APC). Recent studies have shown that the prevalence of APC resistance is associated with severe pregnancy-induced hypertension (PIH). Our objective was to determine whether the factor V Leiden mutation is more prevalent in patients who developed severe PIH than in normotensive pregnant women. In 70 women with a history of severe PIH, of whom 15 had pre-eclampsia, we investigated common coagulation factors as well as APC resistance (factor V related). We found that seven of these 70 women showed low values for APC. Out of these, five were heterozygous and none was homozygous for factor V Leiden mutation. In a control group of normotensive pregnant women we found a 3.0% rate of APC resistance and a 3.0% rate of carriers of the Leiden mutation. These results indicate a significantly higher prevalence of both APC resistance and factor V Leiden mutation in women with severe PIH. Placental infarctions and micro-embolisms are considered to be one of the principle pathophysiological changes in severe PIH. Our results suggest that APC resistance is a risk factor for severe PIH, in addition to its well-known role in macrothrombo-embolism.