Adrenergic reactivity after inhibition of nitric oxide synthesis in the cerebral circulation of awake goats

The interaction between nitric oxide (NO) and adrenergic reactivity in the cerebral circulation was studied using in vivo and in vitro preparations. Blood flow to one brain hemisphere (cerebral blood flow) was electromagnetically measured in conscious goats, and the effects of norepinephrine, tyramine and cervical sympathetic nerve stimulation were recorded before (control) and after inhibition of NO formation with Nw-nitro-l-arginine methyl ester (l-NAME). The responses to norepinephrine, tyramine and electrical field stimulation were also recorded in segments, 4 mm in length, from the goat's middle cerebral artery under control conditions and after l-NAME. In vivo, l-NAME (10 goats, 47 mg kg-1 administered i.v.) reduced resting cerebral blood flow by 37+/-2%, increased mean systemic arterial pressure by 24+/-3%, reduced heart rate by 35+/-2%, and decreased cerebrovascular conductance by 52+/-2% (all P<0.01). Norepinephrine (0.3-9 microgram), tyramine (50-500 microgram), and supramaximal electrical sympathetic cervical nerve stimulation (1. 5-6 Hz) decreased cerebrovascular conductance, and these decreases were significantly higher after l-NAME than under control conditions, remaining higher for about 48 h after this treatment. Norepinephrine (10-8-10-3 M), tyramine (10-6-10-3 M) and electrical field stimulation (1.5-6 Hz) contracted isolated cerebral arteries, and the maximal contraction, but not the sensitivity, was significantly higher in the arteries treated than in non-treated with l-NAME (10-4 M). Therefore, the reactivity of cerebral vasculature to exogenous and endogenous norepinephrine may be increased after inhibition of NO synthesis. This increase might be related, at least in part, to changes at postjunctional level in the adrenergic innervation of the vessel wall, and it might contribute to the observed decreases in resting cerebral blood flow after inhibition of NO synthesis.     

Contribution and importance of wine spirit to the port wine final quality—initial approach

The commercial wine spirit used for this study revealed that the aldehyde content mainly comprises acetaldehyde but other aldehydes such as propionaldehyde, 2‐methylbutyraldehyde, isovaleraldehyde, methylglyoxal, benzaldehyde and others are also present in significant amounts. A typical grape must was used to assess the influence of wine spirit in the analytical and sensorial characteristics of fortified wines. Decreasing levels of anthocyanins, as well the increase in the red colour and tanning capacity, were observed, and seem to be positively correlated with the increase of the aldehyde content present in the wine spirits used to fortify the must. Using the CIE L*a*b* system, this aldehyde content present in the spirit used seemed to be correlated with the decrease of the wines' lightness (darkening effect), the displacement of the hue angle to higher values (yellowing effect) and the increase of the chromaticity (colour saturation) of the wines. Copyright © 2005 Society of Chemical Industry     

Automatic Synthesis of Motion Estimation Processors Based on a New Class of Hardware Architectures

A new class of fully parameterizable multiple array architectures for motion estimation in video sequences based on the Full-Search Block-Matching algorithm is proposed in this paper. This class is based on a new and efficient AB2 single array architecture with minimum latency, maximum throughput and full utilization of the hardware resources. It provides the ability to configure the target processor within the boundary values imposed for the configuration parameters concerning the algorithm setup, the processing time and the circuit area. With this purpose, a software configuration tool has been implemented to determine the set of possible configurations which fulfill the requisites of a given video coder. Experimental results using both FPGA and ASIC technologies are presented. In particular, the implementation of a single array processor configuration on a single-chip is illustrated, evidencing the ability to estimate motion vectors in real-time.     

A new control strategy for an AC/DC converter based on a piezoelectric transformer

Piezoelectric transformers (PTs) are an attractive solution to reduce size and weight in ac/dc converters. In this paper, a PT-based topology is presented together with a control method. As an application, an 8-W ac/dc adapter (110 V/sub AC/ input, 12 V/sub DC/ output) is presented operating at frequencies around 500 kHz.     

Response of coronary microvascular collaterals to activation of ATP-sensitive K+ channels

The feasibility of intragenerically characterizing bifidobacteria by a comparison of a short region within the recA gene was tested. An approximately 300 bp fragment of the recA gene was PCR-amplified from six species from the genus Bifidobacterium using primers directed to two universally conserved regions of the recA gene. A phylogenetic analysis of the sequenced recA products compared favorably to classification based on the 16S rRNA sequences of the species tested. To apply this rapid methodology to unknown human intestinal bifidobacteria, 46 isolates were randomly chosen from the feces of four subjects and initially characterized by RFLP analysis of a PCR-amplified region of their 16S RNA genes. From a representative of the dominant RFLP family in each of the subjects, the recA segment was PCR-amplified, sequenced and phylogenetically analyzed. All four isolates were found to be related to one another and to B. longum and B. infantis. These results illustrate that the recA gene may be useful for intrageneric phylogenetic analysis as well as for the identification of unknown fecal bifidobacteria.     

In vivo and in vitro action of endothelin-1 on goat cerebrovascular bed

This study concerned the effects and mechanisms of action of endothelin-1 on the cerebral circulation. Cerebral blood flow was electromagnetically measured in awake goats. Endothelin-1 (0.01-0.3 nmol) produced dose-dependent decreases in this flow (maximal reduction = 34%) and increases in cerebrovascular resistance (maximal increase = 74%) (P < 0.01). IRL 1620 (Suc-[Glu9, Ala11,15]endothelin-1-(8-21), agonist for endothelin ET(B) receptors, 0.01-0.3 nmol) slightly decreased cerebral blood flow. The effects of endothelin-1, but not those of IRL 1620, on cerebral blood flow were diminished by 50% during infusion of the antagonist for endothelin ET(A) receptors, BQ-123 (cyclo-(D-Asp-Pro-D-Val-Leu-Trp), 2 nmol min(-1)), but not affected during infusion of the antagonist for endothelin ET(B) receptors, BQ-788 (N-[N-[N-[(2,6-dimethyl-1-piperidinyl)carbonyl]-4-methyl-L-Leucyl-1-(met hoxycarbonyl)-D-tryptophyl]-Dnorleucine monosodium), 2 nmol min(-1)). Intravenous administration of NW-nitro-L-arginine methyl ester (L-NAME, 47 mg kg(-1)) or NW-nitro-L-arginine (L-NNA, 47 mg kg(-1)) reduced basal cerebral blood flow by 39 and 33%, increased cerebrovascular resistance by 108 and 98% and mean arterial pressure by 23 and 17%, and decreased heart rate by 27 and 25%, respectively (all at least P < 0.05). The increases in cerebrovascular resistance (as absolute values) induced by endothelin-1 were not affected during either L-NAME or L-NNA (as absolute values and percentages). Intravenous administration of meclofenamate (5 mg kg(-1)) did not change the cerebrovascular effects of endothelin-1 and IRL 1620. In isolated goat cerebral arteries under control, resting conditions, endothelin-1 (10(-11)-10(-7) M) induced concentration-dependent contractions (EC50 = 4.78 X 10(-9) M; maximal contraction = 3177+/-129 mg), whereas IRL 1620 (10(-11)-10(-7) M) produced no effect. This contraction produced by endothelin-1 was competitively blocked by BQ-123 (10(-7)-3 X 10(-6) M), and was not affected by BQ-788 (10(-6) and 10(-5) M). L-NAME (10(-4) M), meclofenamate (10(-5) M), indomethacin (10(-5) M), L-NAME (10(-4) M) plus meclofenamate (10(-5) M) and phosphoramidon (10(-4) M) did not affect the contraction in response to endothelin-1. Endothelium removal increased the response to endothelin-1, as well as the BQ-123 antagonism against endothelin-1 (pA2 values, 7.62 vs. 6.88; P < 0.01). In both intact and de-endothelized arteries precontracted with prostaglandin F2alpha endothelin-1 induced a further contraction, and IRL 1620 caused no effect. These results suggest that: (1) endothelin-1 produces cerebral vasoconstriction by activating endothelin ET(A) receptors probably located in smooth muscle; (2) endothelin ET(B) receptors, nitric oxide and prostanoids might be not involved in the cerebrovascular action of endothelin-1, and (3) endothelium removal may increase cerebrovascular reactivity by increasing sensitivity of endothelin ET(A) receptors to endothelin-1.     

Transposition of the EU cogeneration directive: A vision for Portugal

The potential for new, small-scale and micro-cogeneration installations in Portugal is very considerable due to the number of potential host buildings. In this work, we discuss the legal framework of the Portuguese energy market, and some modifications to accommodate the Directive, 2004/8/EC are stressed. A practical case of cogeneration is also presented, showing the application of the Annex III (b) and (c) of the Cogeneration Directive. The practical case presented shows that micro CHP can be considered highly efficient, with parameters calculated with the Directive rules. Two main improvements in Portugal's energy policy are important: improvement on the permission to access grid system and improvement on support mechanisms indexing it to PES. The Cogeneration Directive transposition is an excellent opportunity to induce a less restrictive framework for the installation of new cogeneration systems, reducing the technological barriers, namely allowing medium-voltage connection with the grid, and improving the revenues provided from these small cogeneration systems. These modifications can improve significantly the number of potential hosts for small-scale cogeneration systems.     

Intraoperative radiotherapy in recurrent gynecological cancer

In ten patients with chronic renal failure (CRF) serum concentrations of alpha 1-acid glycoprotein, alpha 1-antitrypsin, prealbumin, hemopexin, transferrin, haptoglobin, C3c and C4 complement components, ceruloplasmin, alpha 2-macroglobulin were determined using Partigen plates before, 30 min. and 2 hours after beginning of HD. Serum concentrations of C3c complement component, prealbumin increased significantly during HD using CU dialyser, but changes during HD using CA dialyser were not significant. Serum concentrations of alpha 1-antitrypsin, hemopexin increased significantly after two hours of HD using CA dialyser, but changes during HD using CU dialyser were again not significant. Serum concentrations of alpha 1-acid glycoprotein, transferrin, haptoglobin, ceruloplasmin, C4 complement component during HD using both dialyzers did not change significantly. Serum concentration of alpha 2-macroglobulin was higher after two hours of HD. The type of dialysis membrane has important influence on changes of serum acute phase proteins during the initial period of HD.