Lessons of slicing membranes: interplay of packing, free area, and lateral diffusion in phospholipid/cholesterol bilayers

We employ 100-ns molecular dynamics simulations to study the influence of cholesterol on structural and dynamic properties of dipalmitoylphosphatidylcholine bilayers in the fluid phase. The effects of the cholesterol content on the bilayer structure are considered by varying the cholesterol concentration between 0 and 50%. We concentrate on the free area in the membrane and investigate quantities that are likely to be affected by changes in the free area and free volume properties. It is found that cholesterol has a strong impact on the free area properties of the bilayer. The changes in the amount of free area are shown to be intimately related to alterations in molecular packing, ordering of phospholipid tails, and behavior of compressibility moduli. Also the behavior of the lateral diffusion of both dipalmitoylphosphatidylcholine and cholesterol molecules with an increasing amount of cholesterol can in part be understood in terms of free area. Summarizing, our results highlight the central role of free area in comprehending the structural and dynamic properties of membranes containing cholesterol.     

Oral health status and change in handgrip strength over a 5-year period in 80-year-old people

Objective: The number of remaining teeth may indicate the extent of life‐long exposure to inflammation, a known risk factor for muscle loss and consequent disability. The aim was to study dental health status as a risk factor for muscle strength loss in very old people. Design: Cross‐sectional and prospective cohort study over a 5‐year follow‐up. Setting: Research laboratory. Participants: One hundred and ninety‐three 80‐year‐old people participated in the baseline examinations. Five years later, 79 survivors were retested. Main outcome measures: Number of remaining teeth, presence of periodontitis and handgrip strength. Results: At baseline, grip strength of men correlated positively with number of teeth but not with the presence of periodontitis. In women, the cross‐sectional associations were not statistically significant. In the prospective analyses, the presence of periodontitis at baseline showed a clear association with a steeper decline in handgrip over the 5‐year follow‐up in both sexes. The values adjusted for gender, height, weight, number of chronic conditions and physical activity were ?28.3% (SE 5.7) among those with periodontitis vs. ?11.9% (SE 3.1, p = 0.015) among those with healthy gingiva. No association between the number of teeth at baseline and change in grip strength over 5 years was observed. Conclusions: The presence of oral inflammation may lead to loss in muscle strength increasing the risk of disability. Therefore, good dental care throughout the life span may decrease risk of disability in old age.     

Array comparative genomic hybridization with cyanin cis-platinum-labeled DNAs

Fluorescent cis-platinum compounds that react with the N7 atom of guanine are useful for labeling nucleic acids influorescence hybridization applications. Here we report that cyanin (CyN) cis-platinum labeling of DNA samples for array comparative genomic hybridizations (arrayCGH) can be achieved reproducibly and reliably. We demonstrate that degrees of labeling of approximately 1% of all nucleotides in test and reference DNA samples with CyN3- and CyN5-cis-platinum produces arrayCGH signal-to-background ratios ranging from 30 to 40. The arrayCGH results achieved during analyses of mouse and human tumor samples were comparable to those achieved using enzymatic labeling. Thus, we conclude that Cy-cis-platinum labeling is an alternative to enzymatic labeling for arrayCGH.     

Perturbations in brain monoamine systems during stress

Monoamines modulate the activity of many neurons and there is evidence that a balanced synthesis of central nervous monoamines is a prerequisite for normal brain functioning. Stress accelerates both release and turnover of brain monoamines and the resulting fluctuations in concentrations affect various parameters within neurotransmitter systems. Acute stress leads to only transient alterations in monoamine systems so that homeostasis can be restored, in contrast, chronic stress accompanied by repetitive and/or prolonged stimulation of monoaminergic neurons can induce a long-lasting imbalance in central nervous neurotransmitter systems. Accordingly, stress-induced changes in brain monoamine systems are suspected to contribute to psychiatric diseases such as depression. The present paper gives a short overview of stress effects on brain monoamines and their receptors.The work presented in this review was in part supported by the German Science Foundation (SFB406, C4 to G.F.). M.J.M. was supported by the DFG grant Fu 174/17–1 and EC Training Through Research (ERBFMBICT 961829).     

Adrenomedullin modulates hemodynamic and cardiac effects of angiotensin II in conscious rats

We examined whether adrenomedullin, a vasoactive peptide expressed in the heart, modulates the increase in blood pressure, changes in systolic and diastolic function, and left ventricular hypertrophy produced by long-term administration of ANG II or norepinephrine in rats. Subcutaneous administration of adrenomedullin (1.5 microg.kg(-1).h(-1)) for 1 wk inhibited the ANG II-induced (33.3 microg.kg(-1).h(-1) sc) increase in mean arterial pressure by 67% (P < 0.001) but had no effect of norepinephrine-induced (300 microg.kg(-1).h(-1) sc) hypertension. Adrenomedullin enhanced the ANG II-induced improvement in systolic function, resulting in a further 9% increase (P < 0.01) in the left ventricular ejection fraction and 19% increase (P < 0.05) in the left ventricular fractional shortening measured by echocardiography, meanwhile norepinephrine-induced changes in systolic function were remained unaffected. Adrenomedullin had no effect on ANG II- or norepinephrine-induced left ventricular hypertrophy or expression of hypertrophy-associated genes, including contractile protein and natriuretic peptide genes. The present study shows that adrenomedullin selectively suppressed the increase in blood pressure and augmented the improvement of systolic function induced by ANG II. Because adrenomedullin had no effects on ANG II- and norepinephrine-induced left ventricular hypertrophy, circulating adrenomedullin appears to act mainly as a regulator of vascular tone and cardiac function.     

Individuals with abnormal phenotype and normal G-banding karyotype: improvement and limitations in the diagnosis by the use of 24-colour FISH

The simultaneous identification, by fluorescence in situ hybridisation (FISH), of each chromosome in a distinct colour became feasible a few years ago. The key question in the application of this and many other developments in molecular cytogenetics to clinical situations is whether the results add significant further information that is relevant to the diagnosis. So far, limited data exist regarding how much improvement the technique brings to the diagnosis of phenotypically abnormal individuals in whom no abnormalities have been detected by conventional G-banding analysis. Because of the lack of a conclusive diagnosis, genetic counselling, estimation of recurrence risk and prenatal diagnosis of these individuals and their relatives is problematic. We report a study with 24-colour whole-chromosome painting of 10 familial and 11 isolated cases with abnormal phenotypes and normal G-banding karyotypes. Previously undetected unbalanced translocations were revealed in two cases. The value and current cost-effectiveness of multicolour FISH for cytogenetic diagnosis is discussed.     

Global patterns in the metacommunity structuring of lake macrophytes: regional variations and driving factors

Oecologia - We studied community–environment relationships of lake macrophytes at two metacommunity scales using data from 16 regions across the world. More specifically, we examined (a)...     

The diet of breeding female wolverines (Gulo gulo) in two areas of Finland

The wolverine (Gulo gulo) hunts and scavenges for food. We examined how the presence of a semi-domesticated reindeer (Rangifer tarandus tarandus) influences the diet of breeding female wolverines in Finland. We compared the dietary composition of wolverines breeding in the reindeer management area (northern Finland) with that of wolverines breeding outside this area (eastern Finland) by analyzing 421 scats collected from six active dens in northern Finland and four dens in eastern Finland during 2004–2006. The occurrence of food sources in the diet was assessed for both areas using logistic mixed-effects models. Diet breadth per study area was also calculated. As expected, semi-domesticated reindeer was the most important food source (66 %) in northern Finland. Mountain hares (Lepus timidus) were the second most important food item (16 %). Wolverines also utilized grouse (7 %), small rodents (6 %), and moose (Alces alces; 4 %) in their diet. In eastern Finland, the most utilized prey species was moose (55 %), while the diet also comprised mountain hares (13 %), domestic pigs (Sus scrofa; 13 %), grouse (11 %), and small rodents (2 %). The diet of wolverines in eastern Finland included more moose and less semi-domesticated reindeers and small rodents than in northern Finland. The niche breadth did not differ between the study areas. In eastern Finland, the diet of wolverines shifted to 55 % moose and 0 % semi-domesticated reindeer; compared to 4 % moose and 66 % semi-domesticated reindeer in northern Finland. Our study highlights the important role of ungulates in the diet of breeding female wolverines. In areas with a low density of medium-sized ungulates, scavenging for wolf- and human-killed moose and carcasses on feeding sites plays an essential role in food acquisition by wolverines.     

Impacts of trichomonosis epidemics on Greenfinch Chloris chloris and Chaffinch Fringilla coelebs populations in Finland

Population consequences of parasites in wild birds are rarely documented. One exception is the decline of British finch populations due to an epidemic caused by the protozoan parasite Trichomonas gallinae. Finch trichomonosis has recently spread from the UK to northern Europe, but its consequences for local finch populations have not been studied. We assessed the extent to which the trichomonosis epidemic affected the Finnish population sizes of European Greenfinch Chloris chloris, Common Chaffinch Fringilla coelebs and a control species, Great Tit Parus major, and the body condition of Greenfinches. The disease was first documented in Finland in 2008 and epidemics were observed mainly in southwestern Finland. Greenfinches showed a significant decline of 47% in breeding numbers and 65% in wintering numbers in southern Finland during 2006–2010. Breeding Chaffinch numbers showed a slight decline (4%) during the same study period that was significant only in central Finland. Great Tit did not show a significant change in breeding numbers. During the initial disease epidemic the body condition of all demographic groups of Greenfinches decreased equally, which suggests that the disease was not selective in respect of age or sex. There were no encounters of Finnish‐ringed Greenfinches or Chaffinches in the UK, which could indicate that the parasite has not necessarily been transferred directly from the UK, but perhaps by migrants from Sweden and Germany.