Neovascular age-related macular degeneration risk based on CFH, LOC387715/HTRA1, and smoking

Background

Age-related macular degeneration (AMD) is the major cause of blindness in the elderly. Those with the neovascular end-stage of disease have irreversible loss of central vision. AMD is a complex disorder in which genetic and environmental factors play a role. Polymorphisms in the complement factor H (CFH) gene, LOC387715, and the HTRA1 promoter are strongly associated with AMD. Smoking also contributes to the etiology. We aimed to provide a model of disease risk based on these factors.

Methods and Findings

We genotyped polymorphisms in CFH and LOC387715/HTRA1 in a case–control study of 401 patients with neovascular AMD and 266 controls without signs of disease, and used the data to produce genetic risk scores for the European-descent population based on haplotypes at these loci and smoking history. CFH and LOC387715/HTRA1 haplotypes and smoking status exerted large effects on AMD susceptibility, enabling risk scores to be generated with appropriate weighting of these three factors. Five common haplotypes of CFH conferred a range of odds ratios (ORs) per copy from 1 to 4.17. Most of the effect of LOC387715/HTRA1 was mediated through one detrimental haplotype (carriage of one copy: OR 2.83; 95% confidence interval [CI] 1.91–4.20), with homozygotes being at particularly high risk (OR 32.83; 95% CI 12.53–86.07). Patients with neovascular macular degeneration had considerably higher scores than those without disease, and risk of blinding AMD rose to 15.5% in the tenth of the population with highest predicted risk.

Conclusions

An individual''s risk of developing AMD in old age can be predicted by combining haplotype data with smoking status. Until there is effective treatment for AMD, encouragement to avoid smoking in those at high genetic risk may be the best option. We estimate that total absence of smoking would have reduced the prevalence of severe AMD by 33%. Unless smoking habits change or preventative treatment becomes available, the prevalence of AMD will rise as a consequence of the increasing longevity of the population.     

Excitation dynamics in Photosystem I from Chlamydomonas reinhardtii. Comparative studies of isolated complexes and whole cells

Identical time-resolved fluorescence measurements with ~ 3.5-ps resolution were performed for three types of PSI preparations from the green alga, Chlamydomonas reinhardtii: isolated PSI cores, isolated PSI–LHCI complexes and PSI–LHCI complexes in whole living cells. Fluorescence decay in these types of PSI preparations has been previously investigated but never under the same experimental conditions. As a result we present consistent picture of excitation dynamics in algal PSI. Temporal evolution of fluorescence spectra can be generally described by three decay components with similar lifetimes in all samples (6–8 ps, 25–30 ps, 166–314 ps). In the PSI cores, the fluorescence decay is dominated by the two fastest components (~ 90%), which can be assigned to excitation energy trapping in the reaction center by reversible primary charge separation. Excitation dynamics in the PSI–LHCI preparations is more complex because of the energy transfer between the LHCI antenna system and the core. The average trapping time of excitations created in the well coupled LHCI antenna system is about 12–15 ps longer than excitations formed in the PSI core antenna. Excitation dynamics in PSI–LHCI complexes in whole living cells is very similar to that observed in isolated complexes. Our data support the view that chlorophylls responsible for the long-wavelength emission are located mostly in LHCI. We also compared in detail our results with the literature data obtained for plant PSI.     

Supported phospholipid bilayers.

Phospholipid bilayers have been formed on glass, quartz, and silicon surfaces by a sequential transfer of two monolayers at a pressure of approximately 40 dyn/cm from the air-water interface to the solid substrates. Lateral diffusion measurements of L-alpha-dipalmitoylphosphatidylcholine (DPPC) bilayers supported on oxidized silicon wafers reveal two sharp phase transitions at temperatures similar to those found in multilayer systems with several different techniques. The diffusion measurements obtained using fluorescence recovery after pattern photobleaching provide evidence for the existence of an intermediate (probably P beta' or ripple) phase in single bilayers. While in the intermediate and high temperature (liquid-crystalline L alpha) phase, the diffusion coefficients do not vary very much with temperature, a strong temperature dependence is observed in the low temperature (gel L beta') phase. This is attributed to defect-mediated diffusion. Lipids in silicon supported bilayers made from L-alpha-dioleoylphosphatidylcholine (DOPC) or L-alpha-dimyristoylphosphatidylcholine (DMPC) diffuse rapidly above their respective chain-melting transition temperatures. Arrhenius plots show straight lines with activation energies of 40.9 and 43.7 kJ/mol, respectively. Supported DPPC bilayers on oxidized silicon form long tubular liposomes when heated through their oxidized silicon form long tubular liposomes when heated through their chain-melting-phase transition, as viewed with epifluorescence microscopy. It is suggested that this is a consequence of the expansion of the lipid on the fixed solid support. Conversely, DOPC bilayers form large void areas on this substrate upon cooling. Large circular membrane defects (holes) are observed under rapid coating conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lactobacilli and azoreductase activity in the murine cecum.

Azoreductase activity in the ceca of mice lacking lactobacilli as members of the normal microflora (reconstituted-lactobacillus-free [RLF] mice) was compared with that of RLF mice whose gastrointestinal tracts were colonized by strains of Lactobacillus delbrueckii and Lactobacillus fermentum. Azoreductase activity was 31% lower in the ceca of mice colonized by lactobacilli.     

Analysis of fecal populations of bifidobacteria and lactobacilli and investigation of the immunological responses of their human hosts to the predominant strains.

The bifidobacterial and lactobacillus populations of fecal samples collected from 10 human subjects were studied. The numbers of bifidobacteria were similar in the fecal samples of all of the subjects, but lactobacillus numbers varied, even between samples collected from the same individual. Analysis of the composition of the bacterial populations by ribotyping and pulsed-field gel electrophoresis to differentiate between strains showed that, at least for the numerically predominant strains, each subject harbored a unique collection of bifidobacteria and lactobacilli. Predominant bifidobacterial and lactobacillus strains detected in the feces of each subject were used in immunological assays (lymphocyte transformation, serum antibody titers) to determine the influence of the bacteria on the immune system of their host. Immunoglobulin G antibodies reactive with lactobacilli were detected at high concentrations; antibodies reactive with bifidobacteria were present at lower concentrations. The antibodies appeared to be genus specific rather than strain specific. The results of the study emphasized the complexity of the relationship that exists between the intestinal microflora and the human host.     

Delta-opioid augments cardiac contraction through β-adrenergic and CGRP-receptor co-signaling

Cardiac epinephrine and calcitonin gene-related peptide (CGRP) are produced by intrinsic cardiac adrenergic cells (ICA cells) residing in human and animal hearts. ICA cells are neuroparicine cells expressing δ-opioid receptors (DOR). We hypothesized that δ-opioid stimulation of ICA cells enhances epinephrine and CGRP release, which results in the augmentation of heart contraction. Rats were injected with DOR-agonist DPDPE (100 μg/kg) with or without 10-min pretreatment with either β-adrenergic receptor (β-AR) blocker propranolol (2mg/kg) or CGRP-receptor (CGRPR) blocker CGRP(8-37) (300 μg/kg), or their combination. Hemodynamics were monitored with echocardiogram and systolic blood pressure (SBP) was monitored via a tail arterial catheter. Changes in left ventricular fraction-shortening (LVFS) and heart rate (HR) were observed at 5-min after DPDPE infusion. At 5-min DPDPE induced a 36 ± 18% (p<0.001) increase of the LVFS, which continues to increase to 51 ± 24% (p<0.0001) by 10 min, and 68 ± 19% (p<0.001) by 20 min. The increase in LVFS was accompanied by the decrease of HR by 9±5% (p<0.01) by 5 min and 11 ± 6% (p<0.001) by 15 min post DPDPE infusion. This magnitude of HR reduction was observed for the remainder of the 20 min. Despite the HR-reduction, cardiac output was increased by 17 ± 8% (p<0.05) and 28±5% (p<0.001) by 5- and 20-min post DPDPE administration, respectively. There was a modest (9 ± 9%, p=0.03) decrease in SBP that was not apparent until 20 min post DPDPE infusion. The positive inotropism of DPDPE was abrogated in animals pretreated with propranolol, CGRP(8-37), or combined propranolol+CGRP(8-37). Furthermore, in whole animal and cardiomyocyte cell culture preparations, DPDPE induced myocardial protein-kinase A (PKA) activation which was abrogated in the animals pretreated with propranolol+CGRP(8-37). DOR agonists augment myocardial contraction through enhanced β-AR and CGRPR co-signaling.     

Application of pattern recognition and feature extraction techniques to volatile constituent metabolic profiles obtained by capillary gas chromatography

The applicability of threshold logic units, a form of nonparametric pattern recognition, to the processing of metabolic profile data obtained by high-efficiency glass capillary column gas chromatography has been investigated. The test data included profiles of the volatile constituents of urine from normal individuals and from individuals with diabetes mellitus. A feature extraction algorithm allowed for dimensionality reduction and indicated the constituents most important in the normal versus pathological distinction. With an optimum number of dimensions, a normal versus pathological prediction rate of 93.75% was achieved. Gas chromatography—mass spectrometry was utilized to identify important profile constituents.     

Interactions of proteins and cholesterol with lipids in bilayer membranes.

Mixtures of lipids and protein, the ATPase from rabbit sarcoplasmic reticulum, were studied by freeze-fracture electron microscopy and by measurement of the amount of fluid lipid with the spin label 2,2,6,6-tetramethylpiperidine-1-oxyl (TEM-PO). In dimyristoyl phosphatidylcholine vesicles the protein molecules were randomly distributed above the transition temperature, Tt, of the lipid and aggregated below Tt. For mixtures of dimyristoyl and dipalmitoyl phosphatidylcholine the existence of fluid and solid domains were shown in the temperature interval predicted from earlier TEMPO measurements. When protein was incorporated into this lipid mixture, freeze-fracture particles were randomly distributed in fluid lipids, or aggregated when only solid lipids were present. In mixtures of dimyristoyl phosphatidylcholine with cholesterol the protein was distributed randomly above the transition temperature of the phosphatidylcholine. Below that transition temperature the protein was excluded from a banded phase of solid lipid in the case of 10 mol% cholesterol. In mixtures containing 20 mol% cholesterol, protein molecules formed linear arrays, 50-200 nm in length, around smooth patches of lipid. Phase diagrams for lipid/cholesterol and lipid/protein systems are proposed which account for many of the available data. A model for increasing solidification of lipid around protein molecules or cholesterol above the transition temperature of the lipid is discussed.     

The production of 5-HETE and leukotriene B in rat neutrophils from carrageenan pleural exudates

Rat neutrophils isolated from three-hour carrageenan pleural exudates actively metabolize arachidonic acid into three major metabolites, HHT, 11-HETE and 15-HETE. However, in the presence of the calcium ionophore, A23187, or the non-ionic detergent, BRIJ 56, these cells also produce 5-HETE and LTB. The production of these lipoxygenase products is calcium dependent. While non-steroidal anti-inflammatory drugs do not affect 5-HETE or LTB production, BW 755C and ETYA inhibit formation of these metabolites from exogenously added arachidonic acid.