Paul Claes

Influence of Conversion of Penicillin-g Into a Basic Derivative On its Accumulation and Subcellular-localization in Cultured Macrophages

beta-Lactam antibiotics do not accumulate in phagocytes, probably because of their acidic character. We therefore synthesized a basic derivative of penicillin G, namely, 14C-labeled N-(3-dimethylamino-propyl)benzylpenicillinamide (ABP), and studied its uptake and subcellular localization in J774 macrophages compared with that of 14C-labeled penicillin G. Whereas the intracellular concentration (Ci) of penicillin G remained lower than its extracellular concentration (Ce), ABP reached a Ci/Ce ratio of 4 to 5. Moreover, approximately 50% of intracellular ABP was found associated with lysosomes after isopycnic centrifugation of cell homogenates in isoosmotic Percoll or hyperosmotic sucrose gradients. The behavior of ABP was thus partly consistent with the model of de Duve et al. (C. de Duve, T. de Barsy, B. Poole, A. Trovet, P. Tulkens, and A. Van Hoof, Biochem. Pharmacol. 23:2495-2531, 1974), in which they described the intralysosomal accumulation of weak organic bases in lysosomes. Although ABP is microbiologically inactive, our results show that beta-lactam antibiotics can be driven into cells by appropriate modification. Further efforts therefore may be warranted in the design of active compounds or prodrugs that may prove useful in the chemotherapy of intracellular infections.

Unsaturated heavy products from. gamma. irradiation of solid forms of 2,3-dimethylbutane. [/sup 60/Co]

Gamma radiolysis at doses from 0.15 to 16 Mrad of solid forms of 2,3-dimethylbutane leads to the formation of saturated and unsaturated heavy products. Three analytical techniques are tested: hydrogenation of radiolysis products, chromatographic retention data, and gc/ms experiments; only the last technique permits identification of unsaturated products from the radiolysis product mixture. The reaction mechanism is not determined; however, the alkenes produced during radiolysis at 77 K play a major role. This study also points out that radiation-induced chemical processes and self-scavenging by radiolysis products in two polycrystalline states show matrix effects.

Effet de la temperature sur la conductivite et la viscosite des systemes eau—sel

Resume Ce travail a pour objet linfluence de la temperature sur la conductivite du systeme Ca(NO 3 ) 2 -H 2 O de 20 a 90°C a des fractions molaires en eau comprises entre 0,8 et 1. La conductivite et la viscosite solutions consituees du melange eutectique LiNO 3 ue5f8KNO 3 et deau ont egalement ete mesurees a toutes compositions et de 150 a 200°C. Levolution des energies dactivation en fonction de la composition change nettement dallure au voisinage des compositions caracterisees par une conductivite maximum. Ces resultats suggerent la transition dun milieu concentre en electrolyte constitue exclusivement dions hydrates a des solutions aqueuses dans lesquelles se trouve egalement le solvant libre.

[Conductivity and viscosity of systems composed of the NH/sub 4/NO/sub 3/-LiNO/sub 3/-NH/sub 4/Cl eutectic mixture and water]

The conductivity, the specific mass and the viscosity of mixtures of water and the eutectic system NH/sub 4/NO/sub 3/-LiNO/sub 3 /-NH/sub 4/Cl have been measured at concentrations ranging from dilute aqueous solutions to the pure molten salt. The conductivity reaches a maximum value at a molar fraction of water (/b X//sub H2O /) of 0.835. The viscosity of the mixtures raises strongly from /b X//sub H2O/=0.2 to /b X//sub H2O/=0, the Walden product remains approximately constant from /b X//sub H2O/=1 to /b X//sub H2O/=0.2. The results are discussed, the water content at the conductivity maximum is sufficient to ensure the primary hydration of all the ions of the solution.

Maximum de conductivite des solutions aqueuses d'electrolytes

Resume Les conductivites et masses specifiques de solutions aqueuses concentrees de sels alcalins et alcalino—terreux ont ete mesurees a 93°C. Le rapport du nombre de moles deau au nombre de moles de sel auquel apparait le maximum de conductivite (R max ) a ete determine. La valeur de R max est imposee essentiellement par la charge du cation. Dans le cas delectrolytes a cation monovalent, R max est de lordre de 8; pour les electrolytes a cation bivalent ce rapport prend une valeur moyenne de 20. Ces rapports sont correles aux nombres dhydratation primaire des ions constitutifs de lelectrolyte. Les conductivites et conductances equivalentes des systemes etudies se regroupent en familles anioniques; dans le domaine de concentration etudie et pour une composition donnee, la valeur de ces proprietes de transport est conditionnee en majeure partie par la nature de lanion.

Unsaturated heavy products from gamma irradiation of solid forms of 2,3-dimethylbutane. II. Radical contribution

For pt.I see ibid., vol.85, p.262-9, 1981. 2,3-dimethylbutane was gamma -irradiated in quenched and annealed solid phases at 77K. Postirradiation scavenging by dissolving the irradiated 2,3DMB in a propane-oxygen mixture at 95K lowered the saturated and unsaturated heavy product /b G/ values by 33 to 75%. From this observation, it is concluded that allyl radicals are trapped in the radiolysis of this solid branched alkane. This paper also summarizes results obtained from ESR studies of gamma -irradiated solid alkanes.

Chemical and Electrochemical-behavior in Molten Alkali Hydroxides .3. Chemistry of Tin(ii) and Tin(iv) in the Naoh-koh Eutectic Mixture and in Pure Naoh

Etude du comportement chimique de letain (II) et de letain (IV) dans leutectique NaOH−KOH a 483 K et dans NaOH fondu, a 623 K. Sn (II) est instable dans les hydroxydes fondus et est oxyde par le solvant. Loxydation de SnO se fait, soit directement dans la phase solide, soit apres sa dissolution sous forme de SnO 2 2− . Son (IV) se dissout dans leutectique sous forme de SnO 3 2− . Sa solubilite, elevee en milieu fondu basique, est faible en milieu fondu acide. Il precipite sous forme de Na 2 SnO 3 quand la concentration de leau est superieure a 4.10 −2 M et sous forme dun melange de SnO 2 et Na 2 SnO 3 dans un milieu plus acide

Application of chronoamperometry to the determination of diffusion coefficients in a solution of a molten salt

A chronoamperometric method has been applied to the measurement of the diffusion coefficient of the Co(II) ion in the LiCl-KCl eutectic melt at a temperature of 710 degrees K. An electrode of variable area is described, the advantage of which is the avoidance of inaccuracies connected with the determination of the active area of the electrode. The diffusion coefficient measured by chromoamperometry is of 1.44*10/sup -5/ cm/sup 2//s; this value is in good agreement with those determined by chronopotentiometry.