Effect of ETA receptor antagonists on cardiovascular responses induced by centrally administered sarafotoxin 6b: role of sympathetic nervous system

The present study was carried out to investigate the cardiovascular effects of centrally administered SRT6b in saline, BQ123 and BMS182874 pretreated male Sprague-Dawley rats, using a radioactive microsphere technique. SRT6b (100 ng, ICV) produced a transient increase (40%) in blood pressure at 5 min followed by a sustained decrease (-42%) at 30 and 60 min in control rats. Total peripheral resistance and heart rate were not significantly altered. Cardiac output increased (16%) at 5 min and decreased 30 and 60 min following SRT6b administration. Central venous pressure was not affected by SRT6b. Regional blood flow and vascular resistance did not change at 5 min following administration of SRT6b. However, a significant decrease in blood flow to the brain, heart, kidneys, liver, spleen, gastrointestinal tract and mesentery and pancreas was observed 30 and 60 min following administration of SRT6b in control (saline treated) rats. Pretreatment with ETA selective receptor antagonists, BQ123 (10 micrograms, ICV) or BMS182874 (50 micrograms, ICV) significantly attenuated the pressor and depressor effects of centrally administered SRT6b. SRT6b induced decrease in blood flow was completely blocked by pretreatment with BQ123 or BMS182874. ET-1 (100 ng, ICV) produced an increase followed by a decrease similar to SRT6b. Reserpine (5 mg/kg, IP) pretreatment attenuated the cardiovascular effects of ET-1. Role of sympathetic nervous system was determined by measuring splanchnic nerve activity. SRT6b when administered in the lateral cerebral ventricle did not produce any significant effect at 5 min, however, a significant decrease in sympathetic nerve activity was observed 30 min after its administration. It is concluded that centrally administered SRT6b produces significant changes in systematic and regional blood circulation which can be completely blocked by ETA receptor antagonist. The cardiovascular effects of centrally administered SRT6b appear to be mediated through the sympathetic nervous system.     

Profile design considerations for minimizing base transit time inSiGe HBT's

A unified closed form analytical model for base transit time of SiGe HBT's for uniform and exponential base dopant distributions with different Ge profiles in the base (e.g., box, trapezoidal, triangular) is reported. The model is subsequently used to study the design of Ge profile for different base doping profiles, including that of epitaxial base transistors. Consistent with the reported results, our unified model predicts that beyond a certain total Ge content, there is very little reduction in τ_b.SiGe. It is further demonstrated that the trapezoidal Ge profile with X_T~0.8W_B gives near optimal base transit time for all doping profiles considered. Our analysis shows that 1) for a given base width and intrinsic base resistance, the exponential base doping profile with Ge yields the least value of τ_{b, SiGe} and 2) for a given peak base doping concentration and the intrinsic base resistance, the uniform base doping with Ge gives minimum τ_{b, SiGe}. Also, the need for keeping the total base Ge content constant while optimizing the Ge profile in the base is emphasized by showing that a false minimum for τ_{b, SiGe} may appear if the total Ge content is not kept constant     

Bcl-2 deregulation leads to inhibition of sodium butyrate-induced apoptosis in human colorectal carcinoma cells

Epidemiological studies have linked dietary fiber to the prevention of human colorectal cancer and suggest that short chain fatty acids such as butyric acid, which is produced by fermentation of dietary fiber in the large intestine, may be an important mediator of the protective effects of fiber. We investigated the role of Bcl-2 deregulation on the sensitivity of colorectal carcinoma cells to undergo butyrate-induced apoptosis. Here we report an inverse relationship between the levels of Bcl-2 and the sensitivity of colorectal carcinoma cell lines to undergo apoptosis in response to butyrate. Overexpression of Bcl-2 in colorectal carcinoma DiFi cells resulted in suppression of butyrate-induced apoptosis and enhanced cell survival in response to butyrate. Butyrate-induced apoptosis was accompanied by inhibition of expression of a 30 kDa protein (p30, immunorecognized by anti-Bcl-2 mAb) and this cellular effect of butyrate was inhibited by Bcl-2 overexpression. These findings suggest that deregulation of Bcl-2 in human colorectal carcinoma cells confers resistance to induction of apoptosis by butyrate, a dietary micronutrient.     

A rule-based approach for robust clump splitting

This paper presents a robust rule-based approach for the splitting of binary clumps that are formed by objects of diverse shapes and sizes. First, the deepest boundary pixels, i.e., the concavity pixels in a clump, are detected using a fast and accurate scheme. Next, concavity-based rules are applied to generate the candidate split lines that join pairs of concavity pixels. A figure of merit is used to determine the best split line from the set of candidate lines. Experimental results show that the proposed approach is robust and accurate.     

Microwave-Assisted Synthesis of Fine Particle Oxides Employing Wet Redox Mixtures

Interaction of electromagnetic radiation with a physical mixture of metal nitrates and amides/hydrazides is observed to initiate high-temperature reactions, useful for realizing several high-temperature ceramic materials. A judicious choice of such redox mixtures undergoes exothermic reactions when they couple with microwave radiation. The coupling of electromagnetic radiation with metal salts and amides/hydrazides depends on the dielectric properties of the individual components in the reaction mixture. The approach has been used to prepare γ-Fe₂O₃, Fe₃O₄, MgCr₂O₄, α-CaCr₂O₄, and La_0.7Ba_0.3MnO₃.     

Traffic classification and scheduling in ATM networks

Virtual paths (VPs) are an integral part of the resource management and control hierarchy of ATM (asynchronous transfer mode) networks. To improve the utilization of network resources and facilitate management and control, source types are organized into traffic classes. Each traffic class is transported by its own virtual path subnetwork. In this paper, we consider issues related to the design of traffic classes. We consider an ATM switch node to which cells arrive from a diverse set of source types. Traffic classes are assumed to be served according to a weighted round robin policy, while cells belonging to a given traffic class are served in first-come-first-served order. We consider the problem of determining the optimal set of traffic classes. Under suitable simplifying assumptions, it is shown that the above problem can be modeled as a set-partitioning problem. The structure of the problem at hand is then exploited to develop an efficient heuristic. Several examples are given to illustrate the developed methodology.Supported partially through NSF Grant NCR-891447 and AT&T Grant 5-23690.     

SYNTHESIS AND CHARACTERIZATION OF CONTROLLED SIZES: POLYSTYRENE LATEXES

Several parameters and their limitations to prepare monodisperse polystyrene particles were discussed. Polystyrene latexes B, C and D of diameter 129.8, 142.8 and 264.5 nm, respectively, were synthesized by emulsion polymerization method. The latex D is almost monodisperse with very low polydispersity of 0.005 while B and C are having polydispersity of 0.1837 and 0.1601. The particle size and particle size distribution of the latexes were determined by a TEM and Brookhaven particle size analyzer. It was observed that the particle size of the latexes decreased with increasing initiator (ammonium persulfate) or surfactant (SDS) concentrations. The surface area of the latexes were calculated by using BET equation on the basis of the amount of nitrogen gas adsorbed at the surface of the particles to form a monolayer. It was observed that the surface area of latex D is less than B and C because of the bigger size of the particles. The average molecular weights, zeta potentials and densities of the latexes were also presented.     

Free convection and mass transfer flow of non-newtonian fluid with thermal diffusion effect

An analytical study is performed to examine the thermal diffusion characteristics of free convection and mass transfer flow in a non-Newtonian fluid (Walters, 1962: liquid B') past a uniformly accelerated infinite vertical plate in the presence of thermal diffusion. The expression for the velocity field is obtained by the Laplace transform technique. The influence of the Soret number (a thermal diffusion parameter) on the velocity field is extensively discussed with the help of graphs.