Effects of adrenoceptor blockade on cardiac hypertrophy and myocardial phospholipids.

Catecholamines have been proposed as a stimulus for the hypertrophic response to pressure overload of the heart and could also mediate the membrane lipid changes associated with cardiac hypertrophy. To address both of these possibilities, cardiac hypertrophy was induced by aortic constriction in the presence or absence of chronic alpha- or beta-adrenoceptor blockade. Heart weights and heart weight to body weight ratios in aortic-constricted rats of the adrenoceptor-blocked and vehicle-treated groups were elevated to the same extent when compared with values in sham-operated rats of each group. Analysis of the fatty acyl composition of the major phospholipid classes revealed that similar changes occurred in vehicle-treated, alpha-blocked, and beta-blocked aortic-constricted rats when compared with respective groups of sham-operated rats. Specifically, linoleic acid was reduced in the phosphatidylcholine, phosphatidylethanolamine (PE), and cardiolipin (CL) fractions in all groups of aortic-constricted rats. This reduction was accompanied by increased docosahexaenoic acid, arachidonic acid, or palmitic acid in phosphatidylcholine; docosahexaenoic acid in phosphatidylethanolamine; and oleic acid in cardiolipin fractions. Adrenoceptor blockade did not prevent or attenuate the major changes in the fatty acyl composition of phospholipids or the increase in heart weight associated with aortic constriction. This suggests that a change in the level of adrenoceptor stimulation is not the stimulus for cardiac hypertrophy or the observed alterations in phospholipid composition in the pressure-overloaded rat heart.     

Impact of the new generation coronary care unit.

A 30-bed coronary care unit with facilities for fluoroscopy, haemodynamic monitoring, mechanical heart assistance, and long-term electrocardiographic monitoring operated at a reasonable cost over five years. Much of the work was entrusted to trained nurses, and there was close consultation with cardiac surgeons over those patients who needed catheterisation or surgery. New procedures greatly reduced the numbers of early deaths from cardiac arrest and cardiac failure but had less influence on late mortality. Hospital mortality for all 3353 patients was 6-8%, and for patients under 65 with definite infarction, who were admitted direct it was 5-7%.     

The relative influence of urban climates on outdoor human energy budgets and skin temperature I. Modeling considerations

An attempt is made to provide a tool for systematically analyzing variations of outdoor human energy budgets and skin temperatures as a result of different urban street canyon geometries and vegetative properties. To this end, three previously developed numerical models were combined. The interaction of the models and the derivation of the necessary human-urban view-factors is discussed. Some sample results are given for non-urban macadam and park plains, to be used later as standards in the comparison of the impact of urban morphology on human comfort.     

Odontometric microdifferentiation of transplanted Mexican Indian populations: Cuanalan and Saltillo

This study documents odontometric variation in four populations of related genetic background. It is found that the transplanted populations of Cuanalan and Saltillo have undergone significant microdifferentiation in tooth size relative to the two home valley populations. The extent and direction of this microdifferentiation is seen as reflecting differential amounts of admixture from African and European sources in demographic subunits of the two transplanted populations. The dental variables found to discriminate significantly between populations are the same variables predicted to be evolutionarily labile by Butler's Field Theory. Principal component analysis confirms the presence of morphological fields in these data and supports the position that each class has a stable tooth, with stability decreasing with increasing distance from the key tooth. The importance of hybridization in determining which variables significantly discriminate between populations is confounded by the effects of development of the dentition in morphogenetic fields. These data suggest the odontometric data provide an adequate, if somewhat conservative, base from which to evaluate microdifferentiation of human populations.     

Pollen in packrat middens

Fossil packrat middens are used to reconstruct late Quaternary environments in the arid Western U.S.A. Airborne pollen is contributed to middens both directly from the air, and through adherence to plant macrofossils. I examined the filtration of atmospheric pollen by Larrea tridentata leaves (resinous, with sparse recumbent hairs), Cercidium microphyllum twigs (glabrous with recumbent hairs) and Sphaeralcea ambigua leaves (covered with stellate hairs) and evaluated the potential biases of scavenged pollen on the interpretation of pollen records from middens. Pollen grains collected from the surfaces of the plants were most numerous during the spring when (airborne) pollen concentrations were high. Of the species investigated, the Sphaeralcea leaves filtered the greatest number of spring pollen grains from the air (3419 grains cm^?2); captured pollen was very low during other seasons. Sticky Larrea leaves continuously captured airborne pollen ( = 246 grains cm^?2). Pollen captured by smooth Cercidium was consistently low ( = 31 grains cm^?2). Only the spring pollen was filtered in sufficient numbers to obtain minimum pollen counts of 200 grains by all 3 taxa. The plants frequently captured greater proportions of their own pollen. Pollen content of packrat middens will reflect the season of plant macrofossil collection and the species composition of the plants incorporated.     

Regulation of the Na+/Ca2+ Exchanger by Pyridine Nucleotide Redox Potential in Ventricular Myocytes

The cardiac Na⁺/Ca²⁺ exchanger (NCX) is the major Ca²⁺ efflux pathway on the sarcolemma, counterbalancing Ca²⁺ influx via L-type Ca²⁺ current during excitation-contraction coupling. Altered NCX activity modulates the sarcoplastic reticulum Ca²⁺ load and can contribute to abnormal Ca²⁺ handling and arrhythmias. NADH/NAD⁺ is the main redox couple controlling mitochondrial energy production, glycolysis, and other redox reactions. Here, we tested whether cytosolic NADH/NAD⁺ redox potential regulates NCX activity in adult cardiomyocytes. NCX current (I_NCX), measured with whole cell patch clamp, was inhibited in response to cytosolic NADH loaded directly via pipette or increased by extracellular lactate perfusion, whereas an increase of mitochondrial NADH had no effect. Reactive oxygen species (ROS) accumulation was enhanced by increasing cytosolic NADH, and NADH-induced I_NCX inhibition was abolished by the H₂O₂ scavenger catalase. NADH-induced ROS accumulation was independent of mitochondrial respiration (rotenone-insensitive) but was inhibited by the flavoenzyme blocker diphenylene iodonium. NADPH oxidase was ruled out as the effector because I_NCX was insensitive to cytosolic NADPH, and NADH-induced ROS and I_NCX inhibition were not abrogated by the specific NADPH oxidase inhibitor gp91ds-tat. This study reveals a novel mechanism of NCX regulation by cytosolic NADH/NAD⁺ redox potential through a ROS-generating NADH-driven flavoprotein oxidase. The mechanism is likely to play a key role in Ca²⁺ homeostasis and the response to alterations in the cytosolic pyridine nucleotide redox state during ischemia-reperfusion or other cardiovascular diseases.     

Hybridization between two parapatric ranid frog species in the northern Sierra Nevada,California, USA

Contact zones between species provide a unique opportunity to test whether taxa can hybridize or not. Cross‐breeding or hybridization between closely related taxa can promote gene flow (introgression) between species, adaptation, or even speciation. Though hybridization events may be short‐lived and difficult to detect in the field, genetic data can provide information about the level of introgression between closely related taxa. Hybridization can promote introgression between species, which may be an important evolutionary mechanism for either homogenization (reversing initial divergence between species) or reproductive isolation (potentially leading to speciation). Here, we used thousands of genetic markers from nuclear DNA to detect hybridization between two parapatric frog species (Rana boylii and Rana sierrae) in the Sierra Nevada of California. Based on principal components analysis, admixture, and analysis of heterozygosity at species diagnostic SNPs, we detected two F1 hybrid individuals in the Feather River basin, as well as a weak signal of introgression and gene flow between the frog species compared with frog populations from two other adjacent watersheds. This study provides the first documentation of hybridization and introgression between these two species, which are of conservation concern.     

Impact of human activities on the reproduction of Hooded Vultures Necrosyrtes monachus in Burkina Faso

During the last decades, the critically endangered Hooded Vulture Necrosyrtes monachus has strongly declined across its African range. Although direct persecution has been suggested as a major cause of this decline, little is known about the impact of humans on reproductive output in West Africa. We studied the impact of human activities on the reproductive output of Hooded Vultures in the Garango area of Burkina Faso. Twenty and 56 nesting attempts were monitored, respectively, during the breeding season in 2013/14 and 2014/15, to determine reproductive success and identify causes of nest failure. Annual breeding success varied between 0.68 and 0.71 chicks fledged per breeding pair per year and productivity was assessed at 0.57 chicks fledged per territorial pair in 2014/15. The main threats imposed by humans were poaching of eggs, chicks and collection of nest materials, leading to 20% (13 out of 64 breeding attempts) of nest failures over the two years. An additional important reason for nest failure was the pruning and (partial) cutting of nest trees. Despite this high level of human interference, we found that Hooded Vulture nest success increased with proximity to human settlements, probably because breeding vultures benefit from protection by people against persecution and disturbance.     

Yield‐biodiversity trade‐off in patchy fields of Miscanthus × giganteus

Increasing crop productivity to meet rising demands for food and energy, but doing so in an environmentally sustainable manner, is one of the greatest challenges for agriculture to date. In Ireland, Miscanthus × giganteus has the potential to become a major feedstock for bioenergy production, but the economic feasibility of its cultivation depends on high yields. Miscanthus fields can have a large number of gaps in crop cover, adversely impacting yield and hence economic viability. Predominantly positive effects of Miscanthus on biodiversity reported from previous research might be attributable to high crop patchiness, particularly during the establishment phase. The aim of this research was to assess crop patchiness on a field scale and to analyse the relationship between Miscanthus yield and species richness and abundance of selected taxa of farmland wildlife. For 14 Miscanthus fields at the end of their establishment phase (4–5 years after planting), which had been planted either on improved grassland (MG) or tilled arable land (MT), we determined patchiness of the crop cover, percentage light penetration (LP) to the lower canopy, Miscanthus shoot density and height, vascular plants and epigeic arthropods. Plant species richness and noncrop vegetation cover in Miscanthus fields increased with increasing patchiness, due to higher levels of LP to the lower canopy. The species richness of ground beetles and the activity density of spiders followed the increase in vegetation cover. Plant species richness and activity density of spiders on both MT and MG fields, as well as vegetation cover and activity density of ground beetles on MG fields, were negatively associated with Miscanthus yield. In conclusion, positive effects of Miscanthus on biodiversity can diminish with increasing productivity. This matter needs to be considered when assessing the relative ecological impacts of developing biomass crops in comparison with other land use.