Lysophosphatidylcholine modulates fibril formation of amyloid beta peptide

Phospholipids are known to influence fibril formation of amyloid beta (Aβ) peptide. Here, we show that lysophosphatidylcholine (LPC), a polar phospholipid, enhances Aβ(1-42) fibril formation, by decreasing the lag time and the critical peptide concentration required for fibril formation, and increasing the fibril elongation rate. Conversely, LPC did not have an enhancing effect on Aβ(1-40) fibril formation, and appeared to be inhibitory. Tyrosine fluorescence spectroscopy showed that LPC altered the fluorescence spectra of Aβ(1-40) and Aβ(1-42) in opposite ways. Further, 8-anilino-1-naphthalene sulfonic acid fluorescence spectroscopy showed that LPC significantly increased the hydrophobicity of Aβ(1-42), but not of Aβ(1-40). Tris-tricine gradient SDS/PAGE revealed that LPC increased the formation of higher-molecular-weight species of Aβ(1-42), including trimers and tetramers. LPC had no such effect on Aβ(1-40), and thus may specifically influence the oligomerization and nucleation processes of Aβ(1-42) in a manner dependent on its native structure. Dot-blot assays confirmed that LPC induced Aβ(1-42) oligomer formation at an early time point. Thus our results indicate that LPC specifically enhances the formation of Aβ(1-42) fibrils, the main component of senile plaques in Alzheimer's disease patients, and may be involved in Alzheimer's disease pathology.     

Five-year prognosis in an incident cohort of people presenting with acute myocardial infarction

Background

Following an AMI, it is important for patients and their physicians to appreciate the subsequent risk of death, and the potential benefits of invasive cardiac procedures and secondary preventive therapy. Studies, to-date, have focused largely on high-risk populations. We wished to determine the risk of death in a population-derived cohort of 2,887 patients after a first acute myocardial infarction (AMI).

Methods

Logistic regression and survival analysis were conducted to investigate the effect of different baseline characteristics, pharmacological therapies and revascularization procedures on coronary heart disease (CHD) and all-cause mortality outcomes.

Results

Within five years 44.4% of patients died (27.1% short-term [<30 days] and 23.7% longer-term [≥30 days]). Percutaneous transluminal coronary angioplasty (Adjusted Hazards Ratio (AHR) = 0.49, 95% Confidence Interval (CI) 0.26–0.93), β-blockers (AHR = 0.58, 95%CI 0.46–0.74) and statins (AHR = 0.60, 95%CI 0.47–0.77) were all associated with significant reductions in longer-term CHD-related mortality. However, not all patients received secondary preventive therapy (8.7%). Diabetes (AHR = 1.83, 95%CI 1.43–2.34), stroke (AHR = 1.73, 95%CI 1.35–2.22), heart failure (AHR = 1.69, 95%CI 1.28–2.22), smoking (AHR = 1.72, 95%CI 1.18–2.51) and obesity (>30 kg/m2; AHR = 1.39, 95%CI 1.01–1.90) increased the risk of longer-term mortality independent of other risk factors.

Conclusions

It is encouraging that the coronary procedure PTCA and pharmacological secondary prevention therapies were found to be strongly associated with an important reduced risk of subsequent death, although not all patients received these interventions. Smoking, being obese and having cardiovascular related disease at baseline were also associated with an increased likelihood of longer-term mortality, independent of other baseline characteristics. Thus, the provision of smoking cessation, advice on diet (for obese patients) and optimal treatment is likely to be crucial for reducing mortality in all patients after AMI.     

Synthesis and biological evaluation of gemcitabine-lipid conjugate (NEO6002)

A novel gemcitabine-lipid conjugate 5 was synthesized and tested for its in vivo efficacy and toxicity. Compound 5 was tested in BxPC-3 human pancreatic tumor model in SCID mice and exhibited promising activity and lower toxicity when compared with Gemzar.     

Expression profiling reveals differences in metabolic gene expression between exercise-induced cardiac effects and maladaptive cardiac hypertrophy

While cardiac hypertrophy elicited by pathological stimuli eventually leads to cardiac dysfunction, exercise-induced hypertrophy does not. This suggests that a beneficial hypertrophic phenotype exists. In search of an underlying molecular substrate we used microarray technology to identify cardiac gene expression in response to exercise. Rats exercised for seven weeks on a treadmill were characterized by invasive blood pressure measurements and echocardiography. RNA was isolated from the left ventricle and analysed on DNA microarrays containing 8740 genes. Selected genes were analysed by quantitative PCR. The exercise program resulted in cardiac hypertrophy without impaired cardiac function. Principal component analysis identified an exercise-induced change in gene expression that was distinct from the program observed in maladaptive hypertrophy. Statistical analysis identified 267 upregulated genes and 62 downregulated genes in response to exercise. Expression changes in genes encoding extracellular matrix proteins, cytoskeletal elements, signalling factors and ribosomal proteins mimicked changes previously described in maladaptive hypertrophy. Our most striking observation was that expression changes of genes involved in beta-oxidation of fatty acids and glucose metabolism differentiate adaptive from maladaptive hypertrophy. Direct comparison to maladaptive hypertrophy was enabled by quantitative PCR of key metabolic enzymes including uncoupling protein 2 (UCP2) and fatty acid translocase (CD36). DNA microarray analysis of gene expression changes in exercise-induced cardiac hypertrophy suggests that a set of genes involved in fatty acid and glucose metabolism could be fundamental to the beneficial phenotype of exercise-induced hypertrophy, as these changes are absent or reversed in maladaptive hypertrophy.     

Genomewide significant linkage to stuttering on chromosome 12

Stuttering is a common and sometimes severe communication disorder, of unknown primary etiology, that exists in populations worldwide. Many types of evidence suggest a genetic contribution to stuttering; however, the complex inheritance of this disorder has hindered identification of these factors. We have employed highly inbred families to increase the power of linkage analysis of this disorder. Forty-four Pakistani families with documented or probable consanguinity, from the city of Lahore and surrounding areas, were included. Each family contained multiple cases of stuttering, which were diagnosed using the Stuttering Severity Instrument. Using the Marshfield Weber 9 marker panel, we performed a genomewide linkage scan focused on affected individuals and their parents. The analysis included 199 genotyped individuals, 144 affected and 55 unaffected. The Pedigree Relationship Statistical Test (PREST) was used to identify pedigrees that required additional specification of inbreeding. Initial nonparametric analysis gave evidence of linkage on chromosomes 1, 5, 7, and 12. Additional genotyping was performed on chromosome 12 to a 5-cM level of resolution, and 16 additional individuals were then included, bringing the number of families to 46. Analysis of the enlarged data set provided consistent evidence of linkage on chromosome 12: the S(homoz) scoring function gave a nonparametric LOD score of 4.61, and a LOD score of 3.51 was obtained using the S(all) scoring function. These results suggest that a locus on chromosome 12q may contain a gene with a large effect in this sample.