Self-Assembly of C3 Symmetric Rigid Macrolactams into Very Polar and Porous Trigonal Crystals

Cyclohexane and cyclotri-β-alanyl have been used as scaffolds for the design of new C₃-symmetric rings incorporating conjugated alkenes and dienes. All three C₃-symmetric lactams share the same triangular shape and their crystal system is trigonal. They all belong to the R3 space group, R3m, R3 and R3c, for the increasingly large 12-, 18- and 24-membered rigid rings, respectively. All lactams stack on top of each other, through H-bonds and van der Waals noncovalent interactions, leading to endless supramolecular cylinders and tubes. The largest member of the family leads to tubes, the central pores of which is wide enough to let water in. A common feature of all the lactams is their very large dipole, of around 9 D, according to DFT calculations. Surprisingly, all the resulting cylinders and tubes pack side by side in the crystals, with all the dipoles pointing to the same direction. As a result, all three crystals are anisotropic and appear to be the first members of a new kind of highly polar crystals.     

Theoretical evaluation of atomic charges to be integrated into conformational analyses of neutral lipids

Conformational analyses of large molecules as fatty acids and triglycerides are usually amenable by molecular mechanics. A correct evaluation of the electrostatic energy term is thus crucial in determining reliable results. In this contribution, we have considered the most abundant fatty acids in biomembranes, i.e., lauric, stearic, oleic, and elaidic acid, and the corresponding triglycerides, i.e., trilaurin, tristearin, triolein, and trielaidin, and estimated the Mulliken and potential-derived charges both at the semiempirical AM 1 and ab initio HF MO STO -3G level. Atomic charges obtained by the Mulliken population analysis do not take into account the full geometry of the molecule. On the contrary, the change of conformation, due to different chains length or the presence of a trans or cis double bond, greatly influences the repartition of the potential-derived charges. A systematic comparative analysis shows that charges calculated by AM 1 are not suitable because as they do not reproduce potential-derived charges obtained by ab initio. © 1993 John Wiley & Sons, Inc.     

Extracorporeal Photochemotherapy (Photopheresis) Induces Apoptosis in Lymphocytes: A Possible Mechanism of Action of PUVA Therapy

Abstract— The mechanism of action of psoralen plus UVA (PUVA) and photopheresis is not entirely understood. These therapies are assumed to be immunomodulating partly by gradually decreasing leukocyte viability. We investigated whether this delayed form of cell death was due to apoptosis. Untreated and treated (PUVA exposed) leukocytes obtained from six patients with systemic sclerosis and (untreated) leukocytes from healthy control individuals were studied. Qualitative gel electrophoresis and quantitative in situ nick translation analysis of DNA fragmentation was performed. Apoptosis of the treated cells did occur (gel electrophoresis) after 24 h. At t = 0 h, immediately after exposure to PUVA, there was no evidence of DNA fragmentation in the treated cells. The percentage of treated cells undergoing apoptosis was 20–55% at t = 24 h ( in situ nick translation). The untreated leukocytes of the patients and the healthy individuals showed no distinctive rise in apoptotic cells. Apoptosis of the leukocytes after PUVA or photopheresis treatment might be a mechanism of action and might explain the therapeutic response.     

Monotonicity properties of interpolation spaces

For any interpolation pair (A ₀ A ₁), Peetre’sK-functional is defined by: $$K\left( {t,a;A_0 ,A_1 } \right) = \mathop {\inf }\limits_{a = a_0 + a_1 } \left( {\left\| {a_0 } \right\|_{A_0 } + t\left\| {a_1 } \right\|_{A_1 } } \right).$$ It is known that for several important interpolation pairs (A ₀,A ₁), all the interpolation spacesA of the pair can be characterised by the property ofK-monotonicity, that is, ifa∈A andK(t, b; A₀, A₁)≦K(t, a; A₀, A₁) for all positivet thenb∈A also. We give a necessary condition for an interpolation pair to have its interpolation spaces characterized byK-monotonicity. We describe a weaker form ofK-monotonicity which holds for all the interpolation spaces of any interpolation pair and show that in a certain sense it is the strongest form of monotonicity which holds in such generality. On the other hand there exist pairs whose interpolation spaces exhibit properties lying somewhere betweenK-monotonicity and weakK-monotonicity. Finally we give an alternative proof of a result of Gunnar Sparr, that all the interpolation spaces for (L _v ^p , L _w ^q ) areK-monotone.     

Optimal decompositions for theK-functional for a couple of Banach lattices

Letf=g _t+h _t be the optimal decomposition for calculating the exact value of theK-functionalK(t, f; ) of an elementf with respect to a couple =(X ₀ ,X ₁) of Banach lattices of measurable functions. It is shown that this decomposition has a rather simple form in many cases where one of the spacesX ₀ andX ₁ is eitherL ^∞ orL ¹. Many examples are given of couples of lattices for which |g _t| increases monotonically a.e. with respect tot. It is shown that this property implies a sharpened estimate from above for the Brudnyi-KrugljakK-divisibility constant γ( ) for the couple. But it is also shown that certain couples do not have this property. These also provide examples of couples of lattices for which γ( ). Research supported by the Technion V. P. R. Fund.     

Synthesis and functional pharmacological effects on human bronchi of 20-hydroxyeicosatetraenoic acid

We have synthesized 20-hydroxyeicosatetraenoic acid (20-HETE) following a new route and delineated its functional effects in human bronchi. Isometric tension measurements were performed, and they demonstrated that synthetic 20-HETE induced a concentration-dependent relaxant effect in ASM on resting tone and on bronchi pre-contracted with methacholine.     

A New Look at the Diels–Alder Transition State

The chronology of π-orbital mixing in the Diels–Alder cycloaddition of butadiene and ethylene differs for the two main interactions, the HOMO_diene–LUMO_dieneophile and HOMO_dienophile–LUMO_diene interactions. The C2−C3 π bond of the cycloadduct is already well developed at the level of the transition state, which is reminiscent of a late transition state.     

Interpolation spaces between the Lipschitz class and the space of continuous functions

It is shown that the complex interpolation spaces and do not coincide with or and also that the couple is not a Calderón couple. Similar results are also obtained for the couples and when .