The direct action of 17 beta-estradiol in isolated omental artery from nonpregnant and pregnant women is related to calcium antagonism

OBJECTIVE: Our purpose was to study the mechanism by which 17 beta-estradiol modulates contractile activity in isolated rings of omental artery from nonpregnant and pregnant patients. STUDY DESIGN: Rings of omental artery with intact endothelium from nonpregnant and pregnant women were mounted in organ chambers for isometric tension recording. The concentration-relaxation relationship to 17 beta-estradiol (10(-7) mol/L to 3 x 10(-5) mol/L) was studied in rings contracted with 60 mmol/L potassium chloride (in both the absence and the presence of tamoxifen, 10(-6) mol/L). The effect of 17 beta-estradiol (10(-5) mol/L) on the contraction induced by 60 mmol/L potassium chloride and on the concentration-contraction relationships to both norepinephrine (10(-9) mol/L to 10(-5) mol/L) and calcium ion (0.05 mmol/L to 2.5 mmol/L in calcium-free depolarizing solution) were studied in the presence and absence of tamoxifen (10(-6) mol/L). The maximal contraction, negative logarithm of the concentration producing 50% relaxation or 50% contraction to the reference 60 mmol/L potassium chloride contraction, and the area under the curve were calculated. Data analysis was by one-way analysis of variance, Newman-Keuls test, and two-sample tests as appropriate. Probability values less than 0.05 in a two-tailed test were considered statistically significant. RESULTS: 17 beta-Estradiol relaxed omental arteries contracted with 60 mmol/L potassium chloride, and this effect was potentiated by tamoxifen in both groups. Incubation of the omental arteries with 17 beta-estradiol inhibited contractions induced by 60 mmol/L potassium chloride in rings from both groups of patients, and tamoxifen did not antagonize this effect in either group. Rings of omental artery from the nonpregnant patients (expressed as percentage of the reference potassium chloride contraction) showed greater contraction than rings from the pregnant women when exposed to norepinephrine, a statistically significant difference. 17 beta-Estradiol decreased the norepinephrine-induced contraction in omental arteries from nonpregnant but not pregnant women in a statistically significant way. Tamoxifen did not influence the effect of norepinephrine for either group. 17 beta-Estradiol inhibited calcium ion-induced contraction similarly in rings of omental artery from both nonpregnant and pregnant patients. Tamoxifen potentiated estradiol-induced inhibition in arteries from pregnant patients. CONCLUSIONS: 17 beta-Estradiol inhibits norepinephrine-induced contractions in omental arteries from nonpregnant but no pregnant patients. The inhibition of the ter sion developed after exposure to potassium chloride, norepinephrine, and calcium ion is caused by a calcium channel blocking action.     

Mesoporous polystyrene nanoparticles synthesized by semicontinuous heterophase polymerization

The synthesis by semicontinuous heterophase polymerization and the characterization of mesoporous crosslinked polystyrene particles in the nanometer range (ca. 30 nm) are reported here. The particles have pores between 6 and 8 nm in diameter and pore volume around 0.40 cm³/g. In spite that the polymerization was not carried out at highly monomer-starved conditions, particles with narrow size distribution were obtained, which is ascribed to inter-particle hetero-coagulation at latter stages of polymerization, due to lack of enough surfactant to cover all the particles even before 45% global conversion.     

A unifying approach to defuzzification and comparison of theoutputs of fuzzy controllers

This paper addresses the defuzzification of the fuzzy set outputs of fuzzy controllers from a comparison or ranking perspective. This is done by emphasizing the fuzzy controller as a decision-making system. Based on the extensive study and justification of the fuzzy-set comparison criteria that were developed and published elsewhere by the author, a ranking and, thus, a defuzzification index is introduced. This index is shown to overcome the disadvantages of the commonly used defuzzification methods whose attempted justifications based on probabilistic arguments have not been successful. In addition, the proposed index is based on the generalization of the Hurwicz criterion that is usually adopted in decision making under nonprobabilistic uncertainty and it encompasses the pessimistic maximin and the optimistic maximax criteria as special cases     

Modeling, authoring and formatting hypermedia documents in the HyperProp system

This paper discusses multimedia and hypermedia modeling, authoring and formatting tools, presenting the proposals of the HyperProp system and comparing them to related work. It also highlights several research challenges that still need to be addressed. Moreover, it stresses the importance of document logical structuring and considers the use of compositions in order to represent context relations, synchronization relations, derivation relations and task relations in hypermedia systems. It discusses temporal and spatial synchronization among multimedia objects and briefly presents the HyperProp graphical authoring and formatting tools. Integration between the proposed system and the WWW is also addressed.     

Synthesis and characterization of thermosensitive core–shell polymeric nanoparticles

Thermosensitive core–shell nanoparticles were synthesized by semicontinuous heterophase polymerization of styrene, followed by a seeded polymerization for forming a shell of poly(N-isopropyl acrylamide) (PNIPAM). Nanoparticles characterization by scanning transmission electronic microscopy showed core–shell morphology with average particle diameters around 40 nm. An inverse dependence of the particle size with temperature in the range 20–55 °C was identified by quasielastic light scattering measurements. As was expected for core–shell particles with PNIPAM as the shell, a volume phase transition near 32 °C was detected. In spite of thermosensitive properties of core–shell nanoparticles synthesized here, the volume percentage loss values were not so high, probably due to their relatively low content of PNIPAM.     

The nitric oxide pathway in pre-eclampsia: pathophysiological implications

Ageing constitutes a risk factor for magnesium deficit. Primary magnesium deficit originates from two etiological mechanisms: deficiency and depletion. Primary magnesium deficiency is due to insufficient magnesium intake. Dietary amounts of magnesium are marginal in the whole population whatever the age. Nutritional deficiencies are more pronounced in institutionalized than in free-living ageing groups. Primary magnesium depletion is due to dysregulation of factors controlling magnesium status: intestinal magnesium hypoabsorption, reduced magnesium bone uptake and mobilisation, sometimes urinary leakage, hyperadrenoglucocorticism by decreased adaptability to stress, insulin-resistance and adrenergic hyporeceptivity. Secondary magnesium deficit in ageing largely results from various pathologies and treatments common to elderly persons: i.e. non insulin dependent diabetes mellitus and use of hypermagnesuric diuretics. Magnesium deficit may participate in the clinical pattern of ageing: mainly neuromuscular, cardiovascular and renal symptomatologies. The consequences of hyperadrenoglucocorticism--whose non response to dexamethasone suppression test appears the simplest marker--may concern immunosuppression, muscle atrophy, centralization of fat mass, osteoporosis, hyperglycemia, hyperlipidemia, atherosclerosis, disturbances in mood and mental performances through accelerated hippocampal ageing particularly. Treatment of magnesium deficiency requires simple oral physiological magnesium supplementation. Treatment of the different types of magnesium depletion leads to a more or less specific control of pathophysiological disturbances of the required magnesium substrate. Open and double blind studies on the effects of the treatments of magnesium deficiency and of magnesium depletions in geriatic populations are too scarce. Further study is necessary to assess the accurate place of magnesium deficit in the physiopathology of ageing.     

A Lean and Green approach for the eco-efficiency assessment on construction sites: description and case study

Clean Technologies and Environmental Policy - Lean and Green seeks to increase added value and reduce waste generation, while also improving environmental sustainability performance in production...     

Reactive extrusion process for the grafting of maleic anhydride onto linear low‐density polyethylene with ultraviolet radiation

In this work, we chemically modified linear low‐density polyethylene with maleic anhydride in the molten state using, in a first step, different doses of ultraviolet irradiation to generate hydroperoxide groups, which were highly reactive at the processing temperature. Then, in a second reactive extrusion step, maleic anhydride was grafted to the linear low‐density polyethylene under different processing conditions. Characterization of the modified and unmodified linear low‐density polyethylene material was performed with Fourier transform infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Amniotic septostomy for the treatment of twin oligohydramnios-polyhydramnios sequence

A mass balance for lead for the year 1989 in the South Coast Air Basin has inputs to the atmosphere of 600 +/- 190 kg/day and outputs of 580 +/- 160 kg/day, showing rough agreement. Stationary sources are responsible for only about 5% of the total lead emissions. The bulk of the lead is emitted from vehicles using leaded gasoline (37%) and unleaded gasoline (15%), as well as from resuspension of previously deposited lead on roads (43%). Over half of the total emitted lead deposits on roads and nearby soil, while about one-third is carried out the basin by wind. A small amount, less than 10%, is deposited on surfaces throughout the basin. These percentages are approximately the same as those in a mass balance for the same region calculated for 1972, when lead emissions from leaded gasoline were about a factor of 70 greater than leaded gas emissions in 1989. When the lead emissions are used as inputs to a simple continuously stirred flow reactor model for the basin, reasonable agreement is obtained between calculated and measured concentrations.     

A strategic framework for improving food security in Arab countries

In 2007 and the first half of 2008, a sharp rise in agricultural commodity and food prices triggered grave concerns about food security, malnutrition and increased poverty. While the threat of a prolonged food-price shock receded in the second half of 2008, many factors underlying the price volatility are likely to persist, and will require careful management if future food-price shocks are to be avoided. This paper suggests three strategies that, together, could reduce vulnerability to price shocks: (1) strengthen safety nets, improve access to family planning services, and promote education; (2) enhance domestic food production and improve rural livelihoods through increased investment in research and development to increase productivity; and (3) reduce exposure to market volatility through more efficient supply chains and better use of financial instruments to hedge risk. The challenge of food security will require a global response, involving governments, international and regional funding and lending institutions, United Nations agencies, non-governmental organizations, civil society, and the private sector.