Physiological changes in platelet aggregation and nitric oxide levels during menstrual cycle in healthy women.

Hormonal levels, mainly those of estrogens, protect women from the appearance of cardiovascular diseases by an increasing nitric oxide (NO) activity. NO is an endogenous vasodilator and antiaggregating substance. We decided to investigate platelet function and plasma levels of nitric oxide during preovulatory and midluteal phases in young and healthy women with normal menstrual cycles (MCs). Nine young, healthy female subjects had recorded three consecutive MCs before entering this program. Platelet-rich plasma (PRP) was used for the determination of platelet aggregation and NO measurements. Moreover, platelet sensitivity to the inhibitory effect of exogenous NO was tested. The EC(50) of collagen showed no differences between the preovulatory (1.36+/-0.16 microg/mL) and the midluteal (1.31+/-0.08 microg/mL; P, NS) phases. However, the EC(90) during the preovulatory phase was higher (2.05+/-0.2 microg/mL) than during the midluteal phase (1.8+/-0.6 microg/mL). Plasma levels of NO were lower during the preovulatory phase (19.1+/-2 microM) in comparison to the midluteal phase (20.9+/-2.3 microM). Interestingly, the exogenous amount of NO to produce at least half of the inhibition of an EC(90) collagen-induced aggregation was higher at the preovulatory phase (323.3+/-60.9 nM) than during the midluteal phase (240.0+/-37.5 nM; P, NS). We propose that during the follicular phase platelets rather use NO produced by the endothelium; therefore, it is necessary to add more agonist to activate those, but it results in higher consumption of circulating NO, whereas during luteal-phase platelets are not able to use NO, requiring lower amounts of agonist and thus resulting in higher plasma levels of NO. This is an interesting fact in research on cardiovascular diseases of women.     

Effect of Drosophila melanogaster Female Size on Male Mating Success

In this study, we examined the influence of female size on mating success in Drosophila melanogaster. The results that were obtained from experiments performed in mating chambers allowed us to confirm the results of previous studies, demonstrating higher mating success of larger D. melanogaster males, and to conclude that female size also affects mating success, either when considering a single male or two competing males. We observed that the advantage for larger males depends on their size relative to that of the female, demonstrating a previously unknown role for female size in mating behavior studies. This effect of female size on mating success depends on various factors: males take longer to initiate courtship toward larger females, large females receive more wing vibrations from males prior to mating, and large females tend to keep moving for longer periods during male courtship. The importance of this finding is discussed in the context of recent reports on sexual conflict in D. melanogaster, in which males were observed to depress fitness in females as a result of intercourse.     

Modeled connectivity of <Emphasis Type="Italic">Acropora millepora</Emphasis> populations from reefs of the Spratly Islands and the greater South China Sea

The Spratly Island archipelago is a remote network of coral reefs and islands in the South China Sea that is a likely source of coral larvae to the greater region, but about which little is known. Using a particle-tracking model driven by oceanographic data from the Coral Triangle region, we simulated both spring and fall spawning events of Acropora millepora, a common coral species, over a 46-yr period (1960–2005). Simulated population biology of A. millepora included the acquisition and loss of competency, settlement over appropriate benthic habitat, and mortality based on experimental data. The simulations aimed to provide insights into the connectivity of reefs within the Spratly Islands, the settlement of larvae on reefs of the greater South China Sea, and the potential dispersal range of reef organisms from the Spratly Islands. Results suggest that (1) the Spratly Islands may be a significant source of A. millepora larvae for the Palawan reefs (Philippines) and some of the most isolated reefs of the South China Sea; and (2) the relatively isolated western Spratly Islands have limited source reefs supplying them with larvae and fewer of their larvae successfully settling on other reefs. Examination of particle dispersal without biology (settlement and mortality) suggests that larval connectivity is possible throughout the South China Sea and into the Coral Triangle region. Strong differences in the spring versus fall larval connectivity and dispersal highlight the need for a greater understanding of spawning dynamics of the region. This study confirms that the Spratly Islands are likely an important source of larvae for the South China Sea and Coral Triangle region.     

Molecular study of the rat liver NADH: Cytochrome c oxidoreductase complex during development and aging

The mechanisms involved in ageing are yet to be fully understood but it is thought that changes produced in energy transfer pathways occurring in the mitochondria may be responsible for the lack of energy typical of the later stages of life. The aim of the present investigation was to determine the enzymatic activity of the liver NADH cytochrome c oxidorectuctase complex (Complex I-III) in mitochondria isolated from the liver of rats of 3 different age groups: lactating, animals (15-17 days), adult females (3-5 months) and old animals (26-30 months). The activities of the unbound Complexes I and III were also determined.An increase in Complex I-III activity was detected during development (142 ± 10 vs. 447 ± 23 mol cyt. c/mg/min, p < 0.001) ang ageing (447 ± 23 vs. 713 ± 45 mol cyt. c/mg//min, p < 0.001). However, unbound Complex I showed a reduction in activity during the ageing period whilst Complex III activity moderately increased. Immunological studies indicated only a moderate increase in the amount of Complex I-III and studies on the purified complex suggested that the increase in activity was due to effects other than an increase in enzyme quantity. The analysis of protein bands and the quantification of prosthetic groups showed particular reductions in the relative concentrations of Complex I subunits including the 51 kDa unit, which binds FMN, confirmed by a similar reduction in levels of the nucleotide. In contrast, 4 of the 5 subunits which increased during the lifetime of the animals corresponded to those of Complex III. These subunits are responsible for the binding of catalytic groups. The results suggest that, in addition to the increase in the amount of enzyme, binding factors between Complexes I and III may also play an important role in the observed increase in Complex I-III activity.     

Impact of an educational video-based strategy on the behavior process associated with colorectal cancer screening: A randomized controlled study

Background: Low public awareness is an important barrier for colorectal cancer screening participation. Aim: To evaluate the impact of educational intervention on the health behavior process, patient knowledge and compliance with colorectal cancer screening in the average-risk population. Methods: 158 subjects (aged 50–79 years) were randomly assigned either to watch a non-medical video or a colorectal cancer educational video. Before and after watching the experimental or control videotape, participants completed a five-item questionnaire that assessed their knowledge about risk factors for colorectal cancer, age of risk, warning symptoms, 5-year prognosis, and incidence. Subjective risk perception for developing colorectal cancer, barriers or benefits of screening, and intention to be screened were also investigated. Finally, subjects received a faecal occult blood test kit and were requested to use and return it within 2 weeks. Results: Participants in the video-based intervention group showed significant improvement in knowledge of colorectal cancer scores (P < 0.001) and decreased barrier scores. The intervention group returned significantly more faecal occult blood tests than controls (69.6% vs. 54.4%, P = 0.035). The intervention had a positive effect on modifying attitudes and intention to take part in screening. Additionally, the intervention was a predictor of compliance (OR 2.0; 95% CI = 1.02–3.84, P = 0.044). Conclusion: Video-based intervention significantly reduced barriers to screening and improved participant awareness and compliance with colorectal cancer screening with faecal occult blood test.     

Temporal integration of pungency

Four experiments explored possible temporal summation in olfactionand the common chemical sense. In one experiment, participantsjudged the perceived magnitude of various concentrations anddurations (1.25–3.75 s) of the pungent odorant ammoniaand the nonpungent odorant isoamyl butyrate. The perceived magnitudeof ammonia increased during an inhalation whereas the magnitudeof isoamyl butyrate did not. Time-intensity trading relationsfor ammonia indicated nearly perfect temporal summation. Inanother experiment, modulation of the concentration of ammoniaduring an inhalation led to assessments of perceived magnitudethat confirmed the high degree of temporal summation seen inthe first experiment. That is, approximately equal time-integratedmass of inhaled ammonia led to approximately equal perceivedintensity. A third experiment indicated that temporal summationfor ammonia arose from its pungency rather than from its odor,a fourth that trigeminally-mediated reflex apnea in responseto ammonia also exhibits temporal summation. The degree of temporalsummation measured with the reflex came very close to that assessedpsychophysically. When stimulated with ammonia, the common chemicalsense behaves more like a totalmass detector than a concentrationdetector. The investigation raises the possibility that theshortterm sensory reaction to most pungent stimuli may followthis simple rule.     

Fungal biodiversity in aquatic habitats

Fungal biodiversity in freshwater, brackish and marine habitats was estimated based on reports in the literature. The taxonomic groups treated were those with species commonly found on submerged substrates in aquatic habitats: Ascomycetes (exclusive of yeasts), Basidiomycetes, Chytridiomycetes, and the non-fungal Saprolegniales in the Class Oomycetes. Based on presence/absence data for a large number and variety of aquatic habitats, about 3,000 fungal species and 138 saprolegnialean species have been reported from aquatic habitats. The greatest number of taxa comprise the Ascomycetes, including mitosporic taxa, and Chytridiomycetes. Taxa of Basidiomycetes are, for the most part, excluded from aquatic habitats. The greatest biodiversity for all groups occurs in temperate areas, followed by Asian tropical areas. This pattern may be an artifact of the location of most of the sampling effort. The least sampled geographic areas include Africa, Australia, China, South America and boreal and tropical regions worldwide. Some species overlap occurs among terrestrial and freshwater taxa but little species overlap occurs among freshwater and marine taxa. We predict that many species remain to be discovered in aquatic habitats given the few taxonomic specialists studying these fungi, the few substrate types studied intensively, and the vast geographical area not yet sampled.     

A protein phosphatase 2A catalytic subunit is a negative regulator of abscisic acid signalling

The key regulatory role of abscisic acid (ABA) in many physiological processes in plants is well established. However, compared with other plant hormones, the molecular mechanisms underlying ABA signalling are poorly characterized. In this work, a specific catalytic subunit of protein phosphatase 2A (PP2Ac-2) has been identified as a component of the signalling pathway that represses responses to ABA. A loss-of-function pp2ac-2 mutant is hypersensitive to ABA. Moreover, pp2ac-2 plants have altered responses in developmental and environmental processes that are mediated by ABA, such as primary and lateral root development, seed germination and responses to drought and high salt and sugar stresses. Conversely, transgenic plants overexpressing PP2Ac-2 are less sensitive to ABA than wild type, a phenotype that is manifested in all the above-mentioned physiological processes. DNA microarray hybridization experiments reveal that PP2Ac-2 is negatively involved in ABA responses through regulation of ABA-dependent gene expression. Moreover, the results obtained indicate that ABA antagonistically regulates PP2Ac-2 expression and PP2Ac-2 activity thus allowing plant sensitivity to the hormone to be reset after induction. Phenotypic, genetic and gene expression data strongly suggest that PP2Ac-2 is a negative regulator of the ABA pathway. Activity of protein phosphatase 2A thus emerges as a key element in the control of ABA signalling.     

Kinetics of the 5′-nucleotidase and the adenosine deaminase in subcellular fractions of rat brain

Suspensions of rat brain microsomes, synaptosomes, and synaptic vesicles were able to convert adenosine to inosine by means of adenosine deaminase. Isosbestic points of this transformation, at 222, 250 and 281 nm, remained unchanged with time-course. This fact suggests that adenosine deaminase (ADA, E.C. 3.5.4.4) is located on the surface of the vesicles whereas purine nucleoside phosphorylase (PNP, E.C. 2.1.2.4) is located inside the vesicles. Kinetic parameters of the particulate 5-nucleotidase (5N, E.C. 3.1.3.5) and adenosine deaminase were analogous to those of the cytosolic enzymes. These results suggest that soluble and particulate enzymes represent different pools of the same molecular species.     

A qualitative mathematical model of the ontogeny of a circadian rhythm in crayfish

Based on experimental work on the ontogeny of the electroretinogram circadian rhythm in crayfish, we present a mathematical model simulating changes in both frequency and amplitude of the electroretinogram oscillation during several developmental stages until shortly before the adult age. Simultaneously, we propose a hypothetical oscillation in the hormonal release whose frequency is imposed on the electroretinogram oscillation. The model consists of two coupled nonlinear oscillators in which a dynamical response is obtained mainly through an Andronov-Hopf bifurcation. Through the construction of the model, a biological hypothesis about the essential elements underlying the ERG circadian rhythm and their interrelations is formulated and discussed.