Ethanol selectively counteracts hypotension evoked by central I(1)-imidazoline but not alpha2-adrenergic receptor activation in spontaneously hypertensive rats

Novel temperature-sensitive liposomes having surface properties that can be controlled by temperature were designed as liposomes coated with poly(N-isopropylacrylamide), which exhibits a hydrated coil to dehydrated globule transition at ca. 32 degrees C. To obtain the polymer with anchoring groups to the liposome, a copolymer of N-isopropylacrylamide and octadecyl acrylate (99:1, mol/mol) was synthesized by radical copolymerization. The copolymer revealed the transition near 30 degrees C. Liposomes made from various phospholipids were prepared by sonication and coated with the copolymer. When dipalmitoylphosphatidylcholine and distearoylphosphatidylcholine were used as liposome lipids, remarkable aggregation and fusion of the copolymer-modified liposomes took place between the transition temperature of the copolymer and the gel-liquid-crystalline transition temperature (Tc) of the lipid membranes. However, above the Tc, association between the liposomes was much less significant, although the copolymer is still hydrophobic. In the case of the copolymer-modified dilauroylphosphatidylcholine liposome, the membrane of which takes on a liquid-crystalline state under the experimental conditions, association between the liposomes also hardly occurred even when the copolymer became hydrophobic. On the other hand, below the transition temperature of the copolymer, the copolymer-modified liposomes were very stable and aggregation of the liposomes was not observed, irrespective of membrane lipid. Results obtained in this study demonstrate that the copolymer chains fixed on the surface of the liposome with a solid membrane promote aggregation and fusion of the liposomes by hydrophobic interactions between the copolymer chains and/or between the copolymer chains and the liposome membranes above the transition temperature of the copolymer.     

Direct evidence for selective involvement of aortic baroreceptors in ethanol-induced impairment of baroreflex control of heart rate

In a previous study, we have shown that ethanol reduced baroreflex control of heart rate (baroreflex sensitivity, BRS) in conscious sham-operated (SO) rats, but not in aortic barodenervated rats, which suggested, by elimination, a role for aortic baroreceptors in the depressant effect of ethanol on BRS. The present study sought direct evidence to support the hypothesis that aortic baroreceptors are selectively influenced by ethanol. The effect of ethanol on BRS measured by evoked increments (phenylephrine) and decrements (nitroprusside) in blood pressure was studied in conscious unrestrained carotid barodenervated (CBD) and SO rats. The experiments were carried out on 2 consecutive days in the same rats and used phenylephrine on one day and nitroprusside on the other. Compared to sham operation, CBD caused an acute rise in mean arterial pressure and heart rate and a significant reduction in BRS. Two days later, mean arterial pressure and heart rate of conscious unrestrained CBD rats subsided to control levels, whereas baroreflex-mediated bradycardic and tachycardic responses were 65 and 35%, respectively, of control values. Administration of ethanol (1 g/kg) produced similar brief pressor and bradycardic responses in CBD and SO rats. In spite of a significantly lower BRS in CBD as compared to SO rats, ethanol (1 g/kg) caused a significant (P < .05) and comparable attenuation of BRS measured by the response to phenylephrine in CBD and SO rats (30% vs. 38%). In contrast, ethanol caused slight nonsignificant reductions in BRS measured by the response to nitroprusside in CBD and SO rats. Blood ethanol concentrations were similar in both groups of rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Steep fronted surges applied to large AC motors-effect of surgecapacitor value and lead length

The line end coil of large AC motors is known to suffer increased inter-turn voltage stress under steep fronted surge conditions. Surge capacitors can be used to slow down the surge rise-time. The effects of capacitor value and lead length on the line end coil voltage are examined. The theoretical and measured waveforms for the line end coil of a 3.3 kV, 1 MW, four-pole induction motor are compared. The results show clearly that when the capacitor lead length approaches 1, even a relatively large capacitor value has little effect     

Efficacy of itraconazole in children with Trichophyton tonsurans tinea capitis

The microbiology of needle aspirates from 40 inflamed cervical lymph glands was studied for aerobic and anaerobic bacteria, fungi and mycobacteria. Forty-two bacterial, 11 mycobacterial and six fungal isolates were isolated. Aerobic bacteria only were recovered in 11 (27.5%), anaerobes alone in five (12.5%) and mixed aerobic and anaerobic bacteria in seven (17.5%). Mycobacterium sp. were recovered in 11 (27.5%) and fungi in six (15%). The recovery of anaerobes was associated with dental infection. Eighteen aerobic bacteria were isolated and the predominant ones were Staphylococcus aureus (eight isolates) and group A streptococci (four). Twenty-four anaerobic bacteria were recovered and the predominant ones were: Prevotella sp. (six), Peptostreptococcus sp. (five), Propionibacterium acnes (four) and Fusobacterium sp. (three). These findings demonstrate the role of anaerobic organisms in cervical lymphadenitis and the need to culture aspirated material from the glands for both aerobic and anaerobic microorganisms.     

Role of glutathione modulation in acrylonitrile-induced gastric DNA damage in rats

Acrylonitrile (VCN) or its reactive metabolites irreversibly interact with gastric DNA in vivo and cause DNA damage. The effect of glutathione (GSH) modulation on VCN-induced genotoxicity and unscheduled DNA repair synthesis (UDRS) in DNA of gastric mucosal tissues was investigated. VCN-induced UDRS was determined: in control rats, rats with depleted gastric GSH contents, and rats treated with sulfhydryl compounds. A single oral dose (23 mg/kg) of VCN induced a time- and dose-dependent increase in gastric UDRS and decrease in GSH levels. While maximal UDRS in gastric mucosa was observed 2 h following oral administration of 23 mg/kg VCN, maximal GSH depletion (50% of control) was detected 4 h following treatment. Increasing the VCN dose to 46 mg/kg caused a further decrease in gastric GSH level (27% of control), while UDRS was elevated. Inhibition of VCN oxidation by treatment of the animals with the cytochrome P450 inhibitor, SKF 525-A, prior to VCN administration caused 65% reduction in VCN-induced UDRS. Treatment of rats with the GSH depletor diethylmaleate (DEM) prior to VCN administration caused 167% increase in UDRS in gastric mucosal tissues. Treatment of the animals with the sulfhydryl compounds, cysteine and penicillamine, prior to VCN administration protected against VCN-induced UDRS. The results demonstrated an inverse and highly significant correlation between gastric GSH levels and VCN-induced UDRS (r = -0.873, P < 0.0001). In conclusion, our study indicates that VCN bioactivation and the homeostasis of gastric GSH may play a major, role in the initial processes underlying VCN-induced gastric carcinogenesis.     

Would LEED-UHI greenery and high albedo strategies mitigate climate change at neighborhood scale in Cairo,Egypt?

Neighborhood has always been of significant interest to built environment stockholders as a basic planning unit. However, any discussion in these concerns, without drawing attention to sustainable microclimate approaches, would still in a mess at a time of increasing population and climate change. Emergence of the sustainable development concept at the mid-20th century and its emphasis led to increasing crucial role that the urban green infrastructure along with reflective materials can play in mitigating neighborhood microclimate’s symptoms of climate change. Considering the lack of studies for urban heat island (UHI) in hot arid regions, particularly in Egypt and the limited number of studies concerning the numerical simulation of all mitigation strategies incorporated, this research studies the mitigation of UHI phenomenon in a case study in Cairo in present and future (2020, 2050 and 2080) through applying the criteria of tree lines, green roofs, high albedo pavements and shading structures within the neighborhood sustainability assessment tool (Leadership in Energy and Environmental Design for Neighborhood; LEED-ND). The microclimatic numerical CFD simulations of ENVI-met 4.0 was used following the measurement of LAI and Albedo of selected Egyptian trees to assess UHI through air and radiant temperature differences before and after applying mitigation strategies. Results demonstrate a considerable ability to acclimatize the microclimate in terms of better conditions in present and future.     

Interaction of buckling modes in castellated steel beams

This paper investigates the behaviour of normal and high strength castellated steel beams under combined lateral torsional and distortional buckling modes. An efficient nonlinear 3D finite element model has been developed for the analysis of the beams. The initial geometric imperfection and material nonlinearities were carefully considered in the analysis. The nonlinear finite element model was verified against tests on castellated beams having different lengths and different cross-sections. Failure loads and interaction of buckling modes as well as load-lateral deflection curves of castellated steel beams were investigated in this study. An extensive parametric study was carried out using the finite element model to study the effects of the change in cross-section geometries, beam length and steel strength on the strength and buckling behaviour of castellated steel beams. The parametric study has shown that the presence of web distortional buckling causes a considerable decrease in the failure load of slender castellated steel beams. It is also shown that the use of high strength steel offers a considerable increase in the failure loads of less slender castellated steel beams. The failure loads predicted from the finite element model were compared with that predicted from Australian Standards for steel beams under lateral torsional buckling. It is shown that the Specification predictions are generally conservative for normal strength castellated steel beams failing by lateral torsional buckling, unconservative for castellated steel beams failing by web distortional buckling and quite conservative for high strength castellated steel beams failing by lateral torsional buckling.     

Nonlinear behaviour of unprotected composite slim floor steel beams exposed to different fire conditions

An efficient nonlinear 3D finite element model has been developed to investigate the structural performance of composite slim floor steel beams with deep profiled steel decking under fire conditions. The composite steel beams were unprotected simply supported with different cross-sectional dimensions, structural steel sections, load ratios during fire and were subjected to different fire scenarios. The nonlinear material properties of steel, composite slim concrete floor and reinforcement bars were incorporated in the model at ambient and elevated temperatures. The interface between the structural steel section and composite slim concrete floor was also considered, allowing the bond behaviour to be modelled and the different components to retain its profile during the deformation of the composite beam. Furthermore the thermal properties of the interface were included in the finite element analysis. The finite element model has been validated against published fire tests on unprotected composite slim floor steel beams. The time–temperature relationships, deformed shapes at failure, time–vertical displacement relationships, failure modes and fire resistances of the composite steel beams were evaluated by the finite element model. Comparisons between predicted behaviour and that recorded in fire tests have shown that the finite element model can accurately predict the behaviour of the composite steel beams under fire conditions. Furthermore, the variables that influence the fire resistance and behaviour of the unprotected composite slim floor steel beams, comprising different load ratios during fire, cross-section geometries, beam length and fire scenarios, were investigated in parametric studies. It is shown that the failure of the composite beams under fire conditions occurred for the standard fire curve, but did not occur for the natural fires. The use of high strength structural steel considerably limited the vertical displacements after fire exposure. It is also shown that presence of additional top reinforcement mesh is necessary for composite beams exposed to short hot natural fires. The fire resistances of the composite beams obtained from the finite element analyses were compared with the design values obtained from the Eurocode 4 for composite beams at elevated temperatures. It is shown that the EC4 predictions are generally conservative for the design of composite slim floor steel beams heated using different fire scenarios.