Effects of ketotifen on human lymphocytes in vitro and in vivo

The effects of the antiasthmatic drug ketotifen (CAS 34580-13-7) on human mononuclear leukocytes were studied in vitro and in vivo. In vitro ketotifen concentration-dependently inhibited mitogen-stimulated lymphocyte proliferation. High ketotifen concentrations also inhibited T-lymphocyte mitogen- and adenosine triphosphate stimulated increases in intracellular Ca2+ in lymphocytes and the U937 human monocyte precursor cell line, respectively; this involved inhibition of both Ca2+ influx and intracellular mobilization. In in vivo experiments, treatment of healthy volunteers with 1 mg ketotifen b.i.d. for 7 d did not alter the number or subset composition of circulating lymphocytes. Moreover, the mitogen-stimulated in vitro proliferation of lymphocytes obtained before and after ketotifen treatment in vivo was similar. It is concluded that high ketotifen concentrations can inhibit the activation of resting lymphocytes in vitro but standard ketotifen treatment does not notably affect the number of function of circulating lymphocytes in vivo.     

On the computation of the real Hurwitz-stability radius

Recently Qiu et al. (1995) obtained a computationally attractive formula for the evaluation of the real stability radius. This formula involves a global maximization over frequency. Here, for the Hurwitz stability case, we show that the frequency range can be limited to a certain finite interval. Numerical experimentation suggests that this interval is often reasonably small     

Uptake of Cm(III) and Eu(III) by calcium silicate hydrates: a solution chemistry and time-resolved laser fluorescence spectroscopy study

The interaction of the two chemical homologues [Cm(III) and Eu(III)] with calcium silicate hydrates (CSH phases) at pH 13.3 has been investigated in batch-type sorption studies using Eu(III) and complemented with time-resolved laser fluorescence spectroscopy (TRLFS) using Cm(III). The sorption data for Eu(III) reveal fast sorption kinetics and a strong uptake by CSH phases with distribution ratios of (6 +/- 3) x 10(5) L kg(-1). Three different Cm(III) species have been identified: A nonfluorescing species, which was identified as a curium hydroxide (surface) precipitate, and two fluorescing Cm(III)/CSH-sorbed species. The fluorescing sorbed species have characteristic emission spectra with main peak maxima at 618.9 and 620.9 nm and fluorescence emission lifetimes of 289 +/- 11 and 1482 +/- 200 micros, respectively. From the fluorescence lifetimes, it was calculated that the two fluorescing Cm(III) species have one or two and no water molecules left in their first coordination sphere, suggesting that these species are incorporated into the CSH structure. A structural model for Cm(III) and Eu(III) incorporation into CSH phases is proposed based on the substitution for Ca at two different types of sites in the CSH structure.     

When is the multiaffine image of a cube a convex polygon?

We give two simple sufficient conditions under which the multiaffine image in the complex plane of an m-dimensional cube is a convex polygon. A third condition which, in some generic sense, is necessary and sufficient is then obtained. Our conditions involve checking the locations of the image of the vertices of the cube. These results help determine whether a parameterized family of polynomials th stable.     

Pattern of cytokines and pharmacomodulation in sepsis induced by cecal ligation and puncture compared with that induced by endotoxin

The production of tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 and their pharmacomodulation were evaluated in a model of polymicrobial sepsis induced in mice by cecal ligation and puncture (CLP) and were compared with the effects of endotoxin (lipopolysaccharide [LPS]) treatment. LPS levels rose as early as 1 h after CLP and increased further after 2 and 21 h. TNF-alpha was detectable in serum, spleen, liver, and lungs during the first 4 h, with a peak 2 h after CLP. IL-1 beta was measurable in serum after 24 h, and levels increased significantly in spleen and liver 4 and 8 h after CLP. IL-6 levels increased significantly in serum throughout the first 16 h after CLP. These cytokines were detectable after LPS injection, with kinetics similar to those after CLP but at a significantly higher level. To cast more light on the differences between these two animal models of septic shock, we studied the effects of different reference drugs. Pretreatment with dexamethasone (DEX); ibuprofen (IBU), an inhibitor of cyclooxygenase; and NG-nitro-L-arginine, an inhibitor of nitric oxide synthase, significantly reduced survival, while chlorpromazine (CPZ) and TNF did not affect it. Only the antibiotics and pentoxifylline significantly increased survival in mice with CLP. However, CPZ and DEX protected the mice from LPS mortality. On inhibiting TNF-alpha with DEX, CPZ, or pentoxifylline, survival was reduced, unchanged, and increased, respectively, and on increasing TNF-alpha with IBU and TNF, survival was decreased or unchanged, respectively, suggesting that the modulation of this cytokine does not play a significant role in sepsis induced by CLP, unlike treatment with LPS. The negative effects of IBU and N(G)-nitro-L-arginine suggest a protective role by prostaglandins and nitric oxide in sepsis induced by CLP.     

A cross-layer approach for stable throughput maximization under channel state uncertainty

Obtaining the stable throughput region of a wireless network, and a policy that achieves this throughput, has attracted the interest of the research community in the past years. A major simplifying assumption in this line of research has been to assume that the network control policy has full access to the current channel conditions at every time a decision is made. However, in practice one may only estimate the actual conditions of the wireless channel process, and hence the network control policy can at most have access to an estimate of the channel which can in fact be highly inaccurate. In this work we determine a stationary joint link activation and routing policy based on a weighted version of the “back-pressure” algorithm that maximizes the stable throughput region of time-varying wireless networks with multiple commodities by having access to only a possibly inaccurate estimate of the true channel state. We further show optimality of this policy within a broad class of stationary, non-stationary, and even anticipative policies under certain mild conditions. The only restriction is that policies in this class have no knowledge on the current true channel state, except what is available through its estimate.

Guardian maps and the generalized stability of parametrized families of matrices and polynomials

The generalized stability of families of real matrices and polynomials is considered. (Generalized stability is meant in the usual sense of confinement of matrix eigenvalues or polynomial zeros to a prescribed domain in the complex plane, and includes Hurwitz and Schur stability as special cases.) Guardian maps and semiguardian maps are introduced as a unifying tool for the study of this problem. These are scalar maps which vanish when their matrix or polynomial argument loses stability. Such maps are exhibited for a wide variety of cases of interest corresponding to generalized stability with respect to domains of the complex plane. In the case of one- and two-parameter families of matrices or polynomials, concise necessary and sufficient conditions for generalized stability are derived. For the general multiparameter case, the problem is transformed into one of checking that a given map is nonzero for the allowed parameter values. This research was supported in part by the National Science Foundation’s Engineering Research Centers Program, NSFD CDR 8803012, and was also supported by the NSF under Grants ECS-86-57561, DMC-84-51515, and by the Air Force Office of Scientific Research under Grant AFOSR-87-0073.     

Novel technique for antenna gain measurement in satellite Earth stations

A novel technique is proposed for the measurement of the gain of antennas used in Earth stations involved in satellite communications. In principle the technique requires a standard-gain reference antenna, automatic level control over a satellite loop, and narrowband detection techniques. Advantages over conventional techniques (line-of-sight or radio star measurement) are claimed including stable received flux, measurement in situ at operational elevation, accurate crosscalibration with other earth-station antennas, and removal of the influence of propagation on the signal level.