Design of peptides: synthesis, crystal structure, molecular conformation, and conformational calculations of N-Boc-L-Phe-Dehydro-Ala-OCH3. It is noteworthy that the dehydro-Ala residue adopts an extended conformation that is different than those observed in dehydro-Phe, dehydro-Leu, and dehydro-Abu. The peptide N-Boc-L-Phe-dehydro-Ala-OCH3 (C18H24N2O5) was synthesized by the usual workup procedure and finally by converting N-Boc-L-Phe-L-Ser-OCH3 to N-Boc-L-Phe-dehydro-Ala- OCH3. It was crystallized from its solution in a methanol-water mixture at room temperature. The crystals belong to the monoclonic space group P2(1), with a = 9.577(1) A, b = 5.195(3) A, c = 19.563(3) A, beta = 94.67(5) degrees, V = 970.1(6) A3, Z = 2, dm = 1.201(5) Mg m-3, dc = 1.197(5) Mg m-3. The structure was determined using direct method procedures. It was refined by a full-matrix least-squares procedure to an R value of 0.048 for 1370 observed reflections. The C2 alpha-C2 beta distance is 1.327(8) A, while the bond angles N2-C2 alpha-C2' and C1'-N2-C2 alpha are 109.8(5) degrees and 127.8(5) degrees, respectively. The backbone adopts a nonspecific conformation with dehydro-Ala in a fully extended conformation with the following torsion angles: theta 1 = 175.2(4) degrees, omega 0 = 170.2(4) degrees, phi 1 = 135.8(5) degrees, psi 1 = -22.6(6) degrees, omega 1 = 168.5(5) degrees, phi 2 = -170.3(5) degrees, psi 2T = -178.6(5) degrees, theta T = 178.4(7) degrees. The rigid planar and trans conformation of dehydro-Ala forces Phe to adopt a strained conformation. The Boc group has a trans-trans conformation.(ABSTRACT TRUNCATED AT 250 WORDS)


Combined use of homo- and heteronuclear coupling constants as restraints in molecular dynamics simulations. A penalty function for scalar coupling constants has been applied in molecular dynamics simulations as an experimental constraint. The function is based on the difference between the coupling constant calculated from the dihedral angle and the experimentally measured coupling constant. The method is illustrated on a model cyclic pentapeptide for which 3JHN-H alpha and 3JHN-C beta, both about the phi backbone dihedral angle, have been measured. The function is efficient in producing structures consistent with the scalar couplings, but removed from the conformation observed in solution. This arises from the lack of J restraints for the psi dihedral angle. Simulations with both nuclear Overhauser effect (NOE) and J-coupling restraints illustrates small but significant differences from simulations using only NOEs.


Molecular dynamics conformational search of six cyclic peptides used in the template assembled synthetic protein approach for protein de novo design. Six cyclic peptides, designed to act as topological templates in the TASP (template assembled synthetic protein) approach in protein de novo design, were investigated employing a 100-ps, 900-K molecular dynamics conformational search. The peptides are composed of two Lys-X-Lys (X = Gly, Ala) tripeptides connected at its N- and C-terminal end by a Pro-Gly motif and a cystine bridge (I), two Pro-Gly units (II), naphthalene derivatives (III), and tetrahydronaphthalene derivatives of different stereochemistry (IV-VI). The molecular dynamics conformational search established that template I had beta-sheet like geometry. Templates II-VI showed different preferential geometries, among them, e.g., distinct preferences for type V turns in Pro-Gly containing peptides and close spatial arrangement of hydrophobic naphthalene moieties. The orientation of the lysine side chains within preferential geometries of the individual templates is analyzed and a tentative evaluation for their potential to stabilize TASP molecules of 4-helix bundle topology is given.


The spectroscopic properties of the lipodepsipeptide, syringomycin E. The spectroscopic properties of syringomycin E, an antibiotic lipodepsinonapeptide associated with pathological states in plants, have been investigated by uv absorbance and CD spectroscopies, and by the synthesis of relevant model compounds. Initial studies [E. Vaillo, A. Ballio, P. L. Luisi, and R. M. Thomas (1990) in Peptides 1990, Giralt, E. & Andreu, D., Eds., Escom Scientific, Leiden, Netherlands] suggested that a significant contribution to the spectra was due to the presence of a zdehydroaminobutyric acid residue in the amino acid sequence. The model peptides N-Boc-L-Phe-delta zAbu-OMe and its analogue, N-Boc-L-Phe-L-Thr-OMe, lacking the unsaturated bond, were synthesized using standard solution chemistry, and a detailed investigation was made in which the spectra of the models and that of syringotoxin (an antibiotic closely related to syringomycin E but without a Phe residue) were compared with those of syringomycin E under a variety of solvent conditions. The uv absorbance spectra of both N-Boc-L-Phe-delta zAbu-OMe and syringomycin E clearly showed the presence of the unsaturated residue while the CD spectra were complex, environmentally sensitive, and contained contributions from both the delta zAbu and Phe residues. In the course of these studies extinction coefficients were obtained for syringomycin E and its dipeptide model. The origins of the uv and CD spectra are discussed in detail, and a comparison is made with the spectra of other, similar lipopeptide antibiotics. Finally, a structural model for syringomycin is proposed in which the changes induced in the spectrum by alterations in the solvent environment are accommodated.


Variable ranges of interactions in polypeptide conformations with a method to complement molecular modeling. Formulations of conformational weights for helix-coil transitions can be extended to substantially more complex situations than are usually pursued. General rules for matrix multiplication that depend parametrically on the interaction ranges and numbers of rotamers of residues are presented. The orders of the matrices of statistical weights can be increased with chain length, so that an individual matrix element can represent any specified single conformation, as needed. By the appropriate choice of interaction ranges and numbers of available conformers, approximations can be introduced in which: (1) an average of the conformations of any chain segment is obtained, (2) specific residue-residue interactions are excluded, or (3) the conformation of a part of the chain is restricted or fixed. The method is appropriate for treating specific interactions in peptides and could be used together with available experimental information to develop models of conformational transitions. As such, the methods represent a class of calculations aimed at more rigorous calculations built around known features of a molecule. The aim is to facilitate calculations that bridge the gap between nonquantitative molecular model building and more rigorous but less directed molecular mechanics calculations. The method can directly include any desired longer range of interactions, if the interaction range is not too long to make impossible the manipulation of the requisite matrices. An outline is presented of an application to treat salt bridges in the C peptide of ribonuclease A.


Interpretation of 25Mg spin relaxation in Mg-DNA solutions: temperature variation and chemical exchange effects. The temperature dependencies of line shapes and spin-lattice relaxation times T1 have been measured for 25Mg in dilute solutions of Na-DNA/NaCl containing varying amounts of added magnesium(II) ions. The 25Mg spectrum is clearly non-Lorentzian, due to the presence of motions modulating the quadrupolar interaction that are slow compared to the inverse of the Larmor frequency. The weakly temperature-dependent line shapes and relaxation rates appear to be influenced by the relatively slow exchange of the Mg2+ ions between the DNA surface and the aqueous bulk phase. The observed temperature dependencies depend on the ratio of total magnesium to DNA phosphate, Mg/P. The line shape as well as the temperature dependence of the line width at half height can be qualitatively reproduced with a two-site discrete exchange model for the quadrupolar relaxation of a spin 5/2 nucleus in isotropic solution. The calculations give a value of the lifetime for magnesium bound to DNA of 4 ms at room temperature. Previously reported temperature-dependent 43Ca relaxation measurements in DNA solution can be reproduced under the assumption of a mean lifetime of bound calcium that is not larger than 2 ms but not smaller than 50 microseconds at room temperature. The temperature variation of T1 for 25Mg has been calculated, giving some qualitative agreement with the data. The correlation time for bound 25Mg has been found to be about 40 ns at room temperature.


Stacking interactions of ApA analogues with modified backbones. CD spectra have been measured as a function of temperature for a number of ApA analogues with modified backbones. Oligonucleotides with these modified backbones are being used as antisense agents having potential as viral therapeutics. Results of these studies show that when a carbonyl is substituted for the phosphate to produce an uncharged backbone, the analogues that have either sugar or morpholino substitution do not stack. In contrast, when a morpholino group is substituted for the sugar and the phosphate is modified so as to be uncharged, there is strong base stacking. Stacking interactions in the phosphorus-linked morpholino analogues are at least as strong as those found in d(ApA). The stacking interactions in ApA are weak by comparison. Singular value decomposition demonstrates that the stacking is two state, and Taylor series decomposition yields a coefficient that measures base stacking interactions. The van't Hoff equation is applied to the base stacking coefficient from the Taylor series fitting to give thermodynamic parameters.


Excluded volume effects on the partition of single- and double-stranded oligodeoxynucleotides between two liquid phases. The distribution coefficients of single- and double-stranded oligodeoxynucleotides in a PEG 8000/phosphate two-phase system are a function of their chain length. Values of the distribution coefficients are in general agreement with a simple extension of a model for excluded volume effects (the "available volume model") which was applied previously to the distribution of proteins in this system. The current results therefore provide a second set of examples for molecules of very different geometry where the distribution added molecules is controlled by excluded volume interactions between those molecules and the PEG 8000 of the two-phase system.


A molecular thermodynamic approach to predict the secondary structure of homopolypeptides in aqueous systems. Under physiological conditions, many polypeptide chains spontaneously fold into discrete and tightly packed three-dimensional structures. The folded polypeptide chain conformation is believed to represent a minimum Gibbs energy of the system, governed by the weak interactions that operate between the amino acid residues and between the residues and the solvent. A semiempirical molecular thermodynamic model is proposed to represent the Gibbs energy of folding of aqueous homopolypeptide systems. The model takes into consideration both the entropy contribution and the enthalpy contribution of folding homopolypeptide chains in aqueous solutions. The entropy contribution is derived from the Flory-Huggins expression for the entropy of mixing. It accounts for the entropy loss in folding a random-coiled polypeptide chain into a specific polypeptide conformation. The enthalpy contribution is derived from a molecular segment-based Non-Random Two Liquid (NRTL) local composition model [H. Renon and J. M. Prausnitz (1968) AIChE J., Vol. 14, pp. 135-142; C.-C. Chen and L. B. Evans (1986) AIChE J., Vol. 32, pp. 444-454], which takes into consideration of the residue-residue, residue-solvent, and solvent-solvent binary physical interactions along with the local compositions of amino acid residues in aqueous homopolypeptides. The UNIFAC group contribution method [A. Fredenslund, R. L. Jones, and J. M. Prausnitz (1975) AIChE J., 21, 1086-1099; A. Fredenslund, J. Gmehling, and P. Rasmussen (1977) Vapor-Liquid Equilibrium Using UNIFAC, Elsevier Scientific Publishing Company, Amsterdam], developed originally to estimate the excess Gibbs energy of solutions of small molecules, was used to estimate the NRTL binary interaction parameters. The model yields a hydrophobicity scale for the 20 amino acid side chains, which compares favorably with established scales [Y. Nozaki and C. Tanford (1971) Journal of Biological Chemistry, Vol. 46, pp. 2211-2217; E. B. Leodidis and T. A. Hatton (1990) Journal of Physical Chemistry, Vol. 94, pp. 6411-6420]. In addition, the model generates qualitatively correct thermodynamic constants and it accurately predicts thermodynamically favorable folding of a number of aqueous homopolypeptides from random-coiled states into alpha-helices. The model further facilitates estimation of the Zimm-Bragg helix growth parameter s and the nucleation parameter sigma for amino acid residues [B. H. Zimm and J. K. Bragg (1959) Journal of Chemical Physics, Vol. 31, pp. 526-535]. The calculated values of the two parameters fall into the ranges suggested by Zimm and Bragg.


Analyzing the normal mode dynamics of macromolecules by the component synthesis method. This paper presents a general method for studying the harmonic dynamics of large biomolecules and molecular complexes. The performance and accuracy of the method applied to a number of molecules are also reported. The basic approach of the method is to divide a macromolecule into a number of smaller components. The local normal modes of the components are first calculated by treating individual components and the interactions between nearest neighboring components. The physical displacements of all atoms are then represented in the local normal mode space, in which a selected range of high-frequency local modes is neglected. The equation of motion of the molecule in the local normal mode space will then have a smaller dimension, and consequently the normal modes of the whole structure, particularly for large molecules, can be solved much more easily. The normal modes of two polypeptides--(Ala)6 and (Ala)12--and a double-helical DNA--d(ATATA).d(TATAT)--are analyzed with this method. Reductions on the dimensions of harmonic dynamic equations for these molecules have been made, with the fraction of the deleted high-frequency modes ranging from 1/2 to 5/6. The calculated low-frequency normal modes are found to be very accurate as compared to the exact solutions by standard procedure. The major advantage of the present approach on macromolecule harmonic dynamics is that the reduction on the dimensionality of the eigenvalue problems can be varied according to the size of molecules, so the method can be easily applied to large macromolecules with controlled accuracy.


Discontinuous volume transitions in ionic gels and their possible involvement in the nerve excitation process. Discontinuous volume changes in polymer gels carrying negatively ionized groups were studied by varying the molarities of univalent and bivalent cations in the bathing solution. These studies offer a sound basis for elucidating the origin of rapid swelling and heat production in nerve fibers associated with the process of excitation.


Vibrational studies of the disulfide group in proteins. VI. General correlations of SS and CS stretch frequencies with disulfide bridge geometry. Normal mode calculations have been done on a range of disulfide bridge conformations in order to determine how the SS stretch and CS stretch frequencies depend on structure. In addition to varying the C alpha C beta SS and NC alpha C beta S dihedral angles, we have varied the phi, psi of the adjoining peptide groups since we have shown that these also influence the above frequencies. In order to obtain structural information from the observed frequencies, we have done a study of the conformational states found in 92 disulfide bridges in 25 known protein structures. This permits making a statistically based correlation between CS stretch frequencies and the possible contributing conformers.


A molecular dynamics study of conformational changes and hydration of left-handed d(CGCGCGCGCGCG)2 in a nonsalt solution. Twelve dinucleotides (one complete turn) of left-handed, flexible, double-helix poly(dG-dC) Z-DNA have been simulated in aqueous solution with K+ counterions for 70 ps. Most of the d(GpC) phosphates have rotated in accordance with a ZI----ZII transition. The ZII conformation was probably partly stabilized by counterions, which coordinate one of the anionic oxygens and the guanine-N7 of the next (5'----3' direction) base. The presence of base-coordinating ions close to the helical axis rotated and pulled about half of the d(CpG) phosphates further into the groove. These ions also gave rise to rather large deviations from the crystal structure (ZI) with their tendency of pulling the bases closer toward the helical axis. A flipping of the orientation about the glycosyl bond from the +sc to the -sc region was observed for one guanosine, also leading to deviations from the crystal structure. Many bridges containing one or two water molecules were found, with a dominance for the latter. They essentially formed a network of intra- and interstrand bridges between anionic and esterified phosphate oxygens. A "spine" of water molecules could be distinguished as a dark zig-zag pattern in the water density map. The lifetime of a bridge containing one water was about twice as long as that of a two-water bridge and it lasted 5-15 times longer than a hydrogen bond in water. The lifetimes were also calculated for a selection of bridge types, in order of decreasing stability: O1P/O2P ... W ... O'4 much greater than O1P/O2P ... W ... guanine-N2 greater than O1P/O2P ... W ... O1P/O2P. The reorientational motion of water molecules in the first hydration shell around selected groups was slowed down considerably compared to bulk water and the decreasing order of correlation times was guanine-N2 greater than O'4 greater than O'3/O'5 greater than O1P/O2P.


The use of UV-visible spectroscopy for the determination of hydrophobic interactions between neuropeptides and membrane model systems. Ultraviolet-visible spectroscopy has been used as a rapid method to evaluate the hydrophobic interactions between a series of cationic and zwitterionic neuropeptides and dipeptides with the hydrophobic core of two membrane model systems; sodium dodecyl sulfate and lysophosphatidylcholine micelles. If a hydrophobic interaction occurs, a 1-nm bathochromic shift is observed in the uv-visible spectrum of the aromatic side chains when going from aqueous solution to a micellar solution. The aromatic residues of substance P, bradykinin, and Des-Arg9 bradykinin all exhibited the 1-nm bathochromic shift in the presence of sodium dodecyl sulfate while those of Met-enkephalin did not. The opposite effects were observed in the presence of lysophosphatidylcholine micelles.


DNA flexibility as a function of allomorphic conformation and of base sequence. Systematic theoretical modeling of symmetric DNA oligomers, carried out earlier for the B conformation, is now extended to A-DNA. In contrast to the previous results, it is found that A-DNA shows no multiplicity of low-energy substate conformations. The possibilities of the Jumna algorithm are subsequently applied to studying deformations of the oligomers. Controlled winding and stretching deformations are used to study how the two allomorphs and different base sequences absorb such external stress. The results help explain the internal mechanics of the DNA double helix and the extent to which fine structure influences this behavior. The results point to some differences between the A and B double helices, but also to many similarities. Sequence effects on flexibility are relatively limited compared to their impact on optimal energy conformations. It is also shown that the conformational substates detected for B-DNA oligomers are preserved under deformation, but have little influence on its energetics.


Electrostatic forces in two lysozymes: calculations and measurements of histidine pKa values. In order to examine the electrostatic forces in globular proteins, pKa values and their ionic strength dependence of His residues of hen egg white lysozyme (HEWL) and human lysozyme (HUML) were measured, and they were compared with those calculated numerically. pKa values of His residues in HEWL, HUML, and short oligopeptides were determined from chemical shift changes of His side chains by 1H-nmr measurements. The associated changes in pKa values in HEWL and HUML were calculated by solving the Poisson-Boltzmann equations numerically for macroscopic dielectric models. The calculated pKa changes and their ionic strength dependence agreed fairly well with the observed ones. The contribution from each residue of each alpha-helix dipole to the pKa values and their ionic strength dependence was analyzed using Green's reciprocity theorem. The results indicate that (1) the pKa of His residues are largely affected by surrounding ionized and polar groups; (2) the ionic strength dependence of the pKa values is determined by the overall charge distributions and their accessibilities to solvent; and (3) alpha-helix dipoles make a significant contribution to the pKa, when the His residue is close to the helix terminus and not fully exposed to the solvent.


Elongational flow studies on DNA in aqueous solution and stress-induced scission of the double helix. Elongational flow techniques are used to investigate the birefringent response and flow-induced molecular scission of monodisperse phage-DNA samples in aqueous solution. A 4-roll mill apparatus was used to characterize the solutions at low stain rates, epsilon less than or equal to 300 s-1, and the opposed jets apparatus used to study fracture of the DNA molecules at strain rates up to 15 x 10(3) s-1. The molecular weight values were measured before and after fracture in elongational flow using the high-resolution technique of pulsed field gel electrophoresis (PFGE). The birefringent response incorporates both rigid and flexible components. The birefringence is nonlocalized and rises gradually to a plateau value, similar to rigid-rod behavior. In addition a certain minimum value in the strain rate is necessary, an onset value epsilon 0, before the signal appears, indicating a flexible component. This behavior is consistent with a hinged-rod model and is similar to that observed for the protein collagen molecule at elevated temperature. We propose that this type of behavior is likely for multistrand rope-like macromolecules where localized separation or partial untwisting of the intertwined chains occurs, creating temporary hinges, in accordance with biochemical evidence for sequence-specific sites of flexibility. Results are presented on the entanglement effects at high concentrations. We have calculated rotational diffusion rates as a function of concentration and molecular weight. Using PFGE to measure the molecular weight profiles, our fracture studies at high strain rates demonstrate chain halving and quartering in accordance with the predictions of the thermally activated barrier to scission theory for single-chain polymers.


Origins and consequences of ligand-induced multiphasic thermal protein denaturation. The presence of subsaturating levels of a high-affinity ligand has been demonstrated both by experiment and calculation to have far-reaching consequences on thermally induced protein denaturation due to the coupling between the protein denaturation and ligand-binding equilibria. Under such circumstances, a protein may undergo biphasic denaturation even though in the absence of ligand it exhibits a thermogram comprised of a single essentially symmetric endotherm. Up to now, the presence of just 2 maxima in the thermogram has been presented merely as an experimental observation or as the result of equilibrium computations. Here we develop a thermodynamic description of the linkage between these equilibria in which the number of cusps present in the thermogram correlates with the number of resolved steps in the plot of saturation level of remaining native protein vs temperature (i.e., the thermal binding curve). During thermally induced denaturation, the concentration of native protein decreases; thus, the native protein in effect is titrated with ligand at constant total ligand concentration. The free ligand concentration The free ligand concentration increases substantially through the release of bound ligand by unfolding protein thereby increasing the saturation level of the remaining native protein. The form of this thermal binding curve is a function of the number of ligand-binding sites on the protein, the magnitudes of the association constants, and the total ligand and total protein concentrations. As a result, the model predicts multiphasic denaturation of a single cooperative unit when the thermal binding curve consists of discrete multiple steps. The presence of only 2 maxima (i.e., a single cusp) in a thermogram for a protein with multiple sites on the native species derives from the form of the thermal binding curve, which in this case is a single-step sigmoidal plot, and not from the predominant denaturation of unliganded and fully liganded native species. In addition, it is shown that, in general, the contributions from the denaturation of individual native protein species are decidedly non-two-state in character; thus, simple deconvolution should not be carried out. The effects of nonzero values of delta Cp and d delta Cp/dT for denaturation and of changes in enthalpy and in heat capacity for ligand binding, as well as the interaction of ligand with the denatured protein, are explored also.


Thermodynamic substantiation of water-bridged collagen structure. A solution of the problem of topology of a hydrogen bond net in a triple helix of collagen is suggested on the basis of an analysis of thermodynamic data on denaturation of phylogenetically different collagen [T. V. Burjanadze (1982), Vol. 21, pp. 1489-1501; T. V. Burjanadze, E. I. Tiktopulo, and P. L. Privalov (1987), Dokl. Akad. Nauk. USSR, Vol. 293, pp. 720-724] as well as on the earlier evaluation of the energy of the OH group of the 4-hydroxyproline bond [A. R. Ward and P. Mason (1973), Journal of Molecular Biology, Vol. 29, pp. 431-435]. It is shown that only the water-bridged collagen structure [G. N. Ramachandran and R. Chandrasekharan (1968), Biopolymers, Vol. 6, pp. 1649-1661; G. N. Ramachandran, M. Bansal, and R. S. Bhatnagar (1973), Biochimica Biophysica Acta, Vol. 322, pp. 166-171; M. Bansal, C. Ramakrishnan, and G. N. Ramachandran (1975), Proceedings of the Indian Academy of Sciences, Vol. 82, pp. 152-164] can explain both the change of thermostability upon proline hydroxylation [J. Rosenbloom, M. Harsch, and S. Jimenez (1973), Archives of Biochemistry and Biophysics, Vol. 158, pp. 478-484] and its phylogenetic change [T. V. Burjanadze (1982)].


Presence of a thermostable domain in the helical part of the type I collagen molecule and its role in the mechanism of triple helix folding. A study has been done of the effect of neutral salts (NaCl and CaCl2) on the mechanism of type I collagen triple helix folding and unfolding in concentrated acetic acid solutions (2-8.8 M). It is shown that in these conditions, thermoabsorption and secondary structure change in heated solutions proceed in two consecutive stages. Salts exert a different destabilizing effect on different sites of the macromolecule, promoting the detection of a thermostable domain. The presence of a thermostable domain permits one to carry out reversible denaturation of collagen and to study the mechanism of the triple helix folding. Proceeding from the mechanism of the triple helix folding, an assumption has been made on the localization of the thermostable domain and its biological role.


Synthesis of new hydrophilic microspheres: optimized carriers for microparticle-enhanced nephelometric immunoassays. To optimize antigen-antibody reactions, we have synthesized chemically well-defined hydrophilic microspheres. Proteins or haptens were covalently linked to these carriers. When the microsphere conjugates were agglutinated by the corresponding antiserum, the size of the complex artificially increased during the immunological reaction. After optimizing various parameters such as the hydrophilic character, repulsion charges, and amount of antigen coupled to the microspheres, we developed a rapid and sensitive immunoassay based on laser light scattering by the complexes.


Conformational studies of anionic melittin analogues: effect of peptide concentration, pH, ionic strength, and temperature--models for protein folding and halophilic proteins. Melittin (MLT), a 26-residue cationic (net charge +5 at pH 7.2) peptide from bee venom, is well known to be a monomeric, approximately random coil; but when its charges are reduced by titration, by acetylation (net charge +2) or succinylation (net charge -2), or by screening by salt, it goes over to tetrameric alpha-helix. The conversion is promoted by raising the peptide concentration. The tetramer is held together by hydrophobic forces. We have changed the net charge to -6 by acylation with acetylcitric anhydride (a new acylating agent); this anionic derivative forms tetrameric helix at neutral pH, without salt, and at relatively low concentration, conditions under which the cationic MLT does not become helical. Thus, a high net charge is not sufficient to prevent association and helix formation. We have synthesized an anionic melittin analogue of MLT (E-MLT; net charge -4) in which all five lysine and arginine residues are replaced with glutamate, and acetyl and succinyl derivatives of E-MLT (net charges -5 and -6). All three of these are resistant to helix formation. They require much higher NaCl or NaClO4 concentration for helix formation than does MLT. Even CaCl2, MgCl2, and spermine.4HCl are less effective in helicizing E-MLT than MLT. MLT, at pH 7.2, shows increasing helix as the peptide concentration increases (8-120 microM), but E-MLT and its acyl derivatives do not. MLT and acylated MLTs in the helical tetramer show both cold- and heat-induced unfolding, with maximum stability near room temperature. At high temperature, a significant amount of residual structure remains. Heating (to 100 degrees C) monomeric MLT (i.e., MLT at low concentration) or E-MLT results in a monotonic increase in negative ellipticity. In 1.0 M NaCl, E-MLT (at sufficiently high concentration) also shows cold and hot unfolding. The results are discussed in respect to charge-charge and charge-dipole interactions, and hydrophobic effects. E-MLT is also discussed in relation to proteins of halophilic bacteria, which have higher proportions of anionic residues than do corresponding proteins of nonhalophiles.


Conformational and ion binding properties of a cyclic octapeptide, cyclo (Ala-Leu-Pro-Gly)2. The conformation and ion-binding characteristics of a cyclic octapeptide, cyclo (Ala-Leu-Pro-Gly)2, in a liphophilic solvent, acetonitrile, have been studied using CD and nmr spectroscopy. The peptide binds preferentially to divalent cations such as calcium, magnesium, and barium. The conformations of the free cyclic peptide and its calcium complex are very similar with well-defined beta- and gamma-turns. The cyclic peptide readily forms equimolar and possibly 2:1 (peptide:cation) complexes with divalent cations.


The electrostatic potential for the phosphodiester group determined from X-ray diffraction. The charge density distribution in the crystal structure of ammonium dimethylphosphate at 123 K has been determined from x-ray diffraction data (MoK alpha) using 8437 reflections with sin theta/lambda less than 1.33 A-1 [NH4+.(CH3)2PO4-, M(r) = 143.08, monoclinic, P2(1)/c, a = 10.007(1), b = 6.926(1), c = 9.599(2) A, beta = 105.40(1) degrees, V = 641.4(3) A3, Z = 4, F000 = 304, Dx = 1.4815 g.cm-3, mu = 3.726 cm-1]. Least-squares structure refinement assuming Stewart's rigid pseudoatom model (variables including Slater-type radial exponents and electron populations for multipole terms extending to octapoles for C, N, O, and P, and dipoles for H) gave R(F2) = 0.039 for all reflections. The dimethylphosphate anion is in the gauche-gauche conformation and has approximate twofold symmetry. One phosphoryl O atom forms three hydrogen bonds and the other forms one. Neither of the ester O atoms is hydrogen bonded. For the dimethylphosphate anion isolated from the crystal structure, a map of the electrostatic potential obtained using the pseudoatom charge parameters shows that the phosphoryl O atoms are considerably more electronegative than the ester O atoms. The electrostatic potential distribution obtained in this way has been fitted by least squares to a system of atom-centered point charges. The potential calculated from these point charges agrees with the experimental result. It also agrees reasonably well with potentials obtained from three other systems of point charges that are widely used as part of the semiempirical force field for molecular mechanics and molecular dynamics calculations involving nucleic acids.


Conformation of diastereomeric peptide sequences: structural analysis of Z-D-Val-Ac6c-Gly-L-Phe-OMe. We have recently undertaken a systematic structural analysis of fully protected tetrapeptides containing at the N- and C-terminus either homo- or heterochiral amino acids, spaced by an achiral dipeptide segment. The interest for this class of peptides derives from the observation that, on reverse-phase (HPLC), the homo- and heterochiral sequences have a markedly different retention times. The diastereomeric sequences, namely Z-(L/D)-Val-X-Y-L-Phe-OMe (X = Sar, Gly, Ac3c, Aib, Ac5c, Ac6c, Deg, Dpg, Dbu, Dip, Dph; Y = Sar, Gly, Ac3c, Aib, Ac5c, Ac6c) show different overall hydrophobicity attributed to a different three-dimensional structure that also depends on the X-Y segment. Therefore, following preliminary studies in solution, we report here the detailed x-ray analysis of the tetrapeptide Z-D-Val-Ac6c-Gly-L-Phe-OMe in order to understand the structural features governing the overall hydrophobicity of linear fully protected tetrapeptides.


Conformations in solution of angiotensin II, and its 1-7 and 1-6 fragments. High-resolution proton spectra at 620 MHz of human angiotensin II (1-8), angiotensin II (1-7), and angiotensin II (1-6) have been obtained in aqueous solution at acidic pH, and in dimethylsulfoxide solution. Complete chemical shift assignments for all three angiotensin peptides were made based on two-dimensional (2D) correlated spectroscopy and 2D-CA-MELSPIN spectra. Based on the measured values of 3JHNCH, the pattern of observed transverse Overhauser effects, and side-chain coupling constants, it is concluded that all three analogues exist in H2O or DMSO-d6 as a mixture of conformers that is largely extended, with negligible content of folded structures, such as beta-turns, gamma-turns, or helix content. The results fit well with those of Nikiforovich et al.


Alpha-elastin coacervate as a protein liquid membrane: effect of pH on transmembrane potential responses. A protein liquid membrane composed of coacervated alpha-elastin, a chemical fragmentation product of the biological elastic fiber protein, functioned as an amphoteric liquid ion-exchange membrane. Ionic permselectivities of the alpha-elastin coacervate membrane to a series of metal chlorides were investigated for the concentration-cell systems by the ordinary electrochemical measurements. Effects of pH on the transmembrane potential responses for NaCl, CaCl2, and MgCl2 systems were examined. Only in the Ca(2+)-containing system did potential responses stay at constant levels against the pH changes, whereas in the other systems, increasing pH caused potential changes, indicating an improvement of cationic permselectivity across the alpha-elastin coacervate membrane. It was suggested that the characteristic Ca2+ transport mechanisms across the alpha-elastin coacervate membrane are related in some way to the polypeptide backbone interactions specific and selective to Ca2+ ions.


The contribution of residue ion pairs to the helical stability of a model peptide. Comparative CD measurements were made on the model helical peptides acetylYEAAAKEAXAKEAAAKAamide and acetylYEAAAEKAXAKEAAAKAamide in which X represents a nonaromatic nonionic residue. The former peptide contains three potential i, i + 4 complementary ion pairs at neutral pH, while the latter peptide contains one potential complementary and two potential antagonistic i, i + 4 ion pairs. The effect of pH and ionic strength on the mean residue ellipticity of these peptides was measured at 222 nm and 0 degrees C. These measurements were analyzed assuming a common two-state helix/coil transition and only i, i, + 4 ion-pair interactions. The analyses suggest that the central ion pairs do modulate helical content while the peripheral ion pairs do not, presumably due to the location of the peripheral ion pairs in the frayed ends of the helix. The complementary central ion pair stabilizes the helix by about 0.4 kcal/mole and the antagonistic central ion pair destabilizes the helix by about 0.2 kcal/mole.


The CD of ligand-DNA systems. 2. Poly(dA-dT) B-DNA. A systematic theoretical study of the CD of [poly(dA-dT)]2 and its complexes with achiral small molecules is presented. The CD spectra of [poly(dA-dT)]2 and of poly(dA):poly(dT) are calculated for various DNA structures using the matrix method. The calculated and experimental spectra agree reasonably well for [poly(dA-dT)]2 but less well for poly(dA):poly(dT). The calculated CD spectrum of [poly(dA-dT)]2 fails to reproduce the wavelength region of 205-245 nm of the experimental spectrum. This discrepancy can be explained by a magnetic dipole allowed transition contributing significantly to the CD spectrum in this region. The induced CD of a transition moment of a molecule bound to [poly(dA-dT)]2 is also calculated. As was the case for [poly(dG-dC)]2, the induced CD of a groove bound molecule is one order of magnitude stronger than that of an intercalated molecule. The calculations also show considerable differences between pyrimidine-purine sites and purine-pyrimidine sites. Both signs and magnitudes of the CD induced into ligands bound in the minor groove agree with experimental observations.


Shape distributions of protein topography. A method is presented for measuring protein surface shape. It is an improvement of an earlier method that intersects a sphere with the solvent-excluded volume of a protein molecule. The new method, called a shape distribution, produces a more sophisticated description of the region of the sphere inside the protein than is provided by simply measuring the region's area or solid angle. This method is applied to the prediction of molecular complexes in three systems: the hemoglobin nonallosteric interface, trypsin and trypsin inhibitor, and heme and apomyoglobin. It does not uniquely predict the correct structure, even though the individual structures are taken from the experimentally determined complex structure. However, it does provide a list of several hundred predicted complexes, one of which is correct, and from which the correct complex might be extracted by a subsequent chemical filter.


IR (vibrational) CD of peptide beta-turns: a theoretical and experimental study of cyclo-(-Gly-Pro-Gly-D-Ala-Pro-). IR vibrational CD (VCD) has been observed for the cyclic pentapeptide cyclo-(-Gly-Pro-Gly-D-Ala-Pro-) in solution in CDBr3. The observed VCD spectra do not resemble the VCD features of any of the previously reported peptide secondary structures, such as alpha-helical, "random coil," or sheet structures, and might be due to the beta-turn contained in this molecule. To shed light onto the origin of the observed spectra, VCD intensity calculations, based on the solution and solid-state structures of cyclo-(-Gly-Pro-Gly-D-Ala-Pro-), have been carried out. In addition, calculated VCD data for pure beta-turns are discussed.


Hydrophobicity scale for proteins based on inverse temperature transitions. In general, proteins fold with hydrophobic residues buried, away from water. Reversible protein folding due to hydrophobic interactions results from inverse temperature transitions where folding occurs on raising the temperature. Because homoiothermic animals constitute an infinite heat reservoir, it is the transition temperature, Tt, not the endothermic heat of the transition, that determines the hydrophobically folded state of polypeptides at body temperature. Reported here is a new hydrophobicity scale based on the values of Tt for each amino acid residue as a guest in a natural repeating peptide sequence, the high polymers of which exhibit reversible inverse temperature transitions. Significantly, a number of ways have been demonstrated for changing Tt such that reversibly lowering Tt from above to below physiological temperature becomes a means of isothermally and reversibly driving hydrophobic folding. Accordingly, controlling Tt becomes a mechanism whereby proteins can be induced to carry out isothermal free energy transduction.


Hydrophobicity of amino acid residues: differential scanning calorimetry and synthesis of the aromatic analogues of the polypentapeptide of elastin. Relative hydrophobicities of aromatic amino acid residues are investigated by using differential scanning calorimetry (DSC) on 10 synthetic copolypentapeptides of poly(VPGVG) of elastin. Utilizing the hydrophobic-driven process of the inverse temperature transition exhibited by these polypentapeptides in aqueous solution, the relative hydrophobicities of Phe, Trp, and Tyr residues are determined by the critical temperature and heat of the transition. The DSC data for the aromatic residue containing copolypentapeptide aqueous solution indicate that tryptophan is the most hydrophobic amino acid residue, phenylalanine the third most hydrophobic on basis of transition temperature and the second on basis of transition heat. For tyrosine, significant differences are observed between the phenolic and the phenoxide anionic states. At pH 7, where tyrosine is protonated, it is found to be the second most hydrophobic amino acid residue on the basis of the transition temperature, whereas on the basis of the heat of transition, it is less hydrophobic than both tryptophan and phenylalanine. Changing the pH from pH 7 to pH 12, for example, for poly[0.8(VPGVG), 0.2(VPGYG)] in aqueous solution shifts the transition temperature from 7 to 49 degrees C with a dramatically reduced heat. On the basis of both the transition temperature scale and the heat of transition, the hydroxylated tyrosine appears less hydrophobic than glycine.


Tumor necrosis factor-alpha gene expression in the tissues of normal mice. Although TNF-alpha is traditionally associated with macrophage activation during neoplasia and acute inflammation, recent Northern blot hybridization studies indicate that gene expression occurs in the absence of pathology. In order to identify the cellular sources of endogenous message and protein, normal mouse tissues were tested for TNF-alpha mRNA using in situ hybridization and for the corresponding protein by immunocytochemistry. Unexpectedly, specific TNF-alpha message was readily detected in hepatocytes, kidney tubule epithelial cells, various populations of spleen cells and neurons. TNF-alpha protein was present in the same liver and kidney cells as those that contained TNF-alpha mRNA, was low in spleen cells, and was absent in neurons. These results suggest that cells other than macrophages are the major sources of TNF-alpha gene products in normal tissues, indicate that regulation is accomplished by more than one mechanism, and are consistent with the postulate that products of this gene contribute to normal physiological processes.


Binding of neutrophil attractant/activation protein-1 (interleukin 8) to resident dermal cells. Putative tissue receptors for leukocyte attractants, including neutrophil attractant/activation protein-1 (interleukin 8, NAP-1/IL-8), have been implicated in the regulation of neutrophil emigration into the tissues. An in-situ binding assay and an ex-vivo autoradiographic approach were used to investigate the binding of radiolabeled NAP-1/IL-8 to human and animal skin. These methods revealed the presence of saturable NAP-1/IL-8-binding sites on the endothelial cells of venules and veins but not arteries or capillaries of the dermis. In addition, the binding of NAP-1/IL-8 to dermal macrophages and perivascular mast cells was observed. We suggest that the NAP-1/IL-8-binding sites described here could be involved in the regulation of NAP-1/IL-8-induced neutrophil emigration.


Pharmacokinetics, safety and immunomodulatory effects of human recombinant interleukin-1 receptor antagonist in healthy humans. A phase I study of human recombinant interleukin-1 receptor antagonist (IL-1ra) was conducted in healthy males between the ages of 18 and 30. Twenty-five volunteers received a single, 3 h continuous intravenous infusion of doses ranging between 1 mg/kg and 10 mg/kg IL-1ra. At 3 h into the infusion, plasma IL-1ra levels were 3.1 micrograms/ml and 29 micrograms/ml for the 1 mg/kg and 10 mg/kg doses, respectively. Post-infusion plasma IL-1ra levels declined rapidly, exhibiting an initial half-life of 21 min and a terminal half-life of 108 min. Clinical, hematological, biochemical, endocrinological and immunomodulatory effects were monitored over 72 h and compared to those of four subjects receiving a 3 h infusion of saline. There were no clinically significant differences between the drug and saline groups in symptoms, physical examinations, complete blood counts, mononuclear cell phenotypes, blood chemistry profiles, serum iron and serum cortisol levels. Peripheral blood mononuclear cells (PBMC) obtained after completion of the IL-1ra infusion synthesized significantly less interleukin 6 ex vivo than PBMC from saline-injected controls. These data suggest that transient blockade of interleukin 1 receptors is safe and does not significantly affect homeostasis.


Induction of inflammatory cytokine release from cultured human monocytes by C-reactive protein. The human acute phase protein, C-reactive protein (CRP), is capable of specifically binding to and modulating the function of mononuclear phagocytes. To investigate whether CRP can also affect the capacity of these cells to produce inflammatory cytokines, enzyme immunoassays and Western blot techniques were used to quantitate interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) produced by freshly-isolated normal human monocytes. CRP induced the rapid release of each cytokine, with significantly elevated levels in culture supernatants at 4 hours and maximal levels of TNF-alpha at 8 hours, and of IL-1 beta and IL-6 at 16 hours of culture. The effects of CRP were dose-dependent; greater than 10-fold increases of each cytokine were observed following culture with greater than or equal to 50 micrograms/ml CRP, concentrations which are often found in the presence of moderate to severe inflammation or tissue injury. The induction of cytokine release by CRP was unaffected by inclusion of 25 micrograms/ml polymyxin-B in culture media, but was completely abrogated by prior boiling of the CRP, a procedure which had no effect on induction of monocyte cytokine release by lipopolysaccharide. The dose-dependent induction of inflammatory cytokines by CRP provides further support for the hypothesis that interaction with mononuclear phagocytes constitutes an important biological role for this acute phase protein.


Interleukin 4 inhibits IL-2-induced proliferation of a human T-leukemia cell line without interfering with p56-LCK kinase activation. Recently we described the establishment in culture and the immunophenotypic and functional characteristics of a human T-leukemia line TALL-103/2 derived from the T-cell receptor (TCR)-gamma/delta subset of T-lymphocytes. TALL-103/2 cells are absolutely dependent on interleukin 2 (IL-2) for their growth and survival in culture and thus provide a model cell line for studies of IL-2 signal transduction in a TCR-gamma/delta T-cell. In this report, we focus on the regulation of SRC-family protein tyrosine kinases (PTKs) by IL-2. TALL-103/2 cells were found to contain p56-LCK, p59-FYN, p62-YES and p53/56-LYN. Stimulation of growth factor-deprived TALL-103/2 cells with IL-2, however, induced increases in the relative activity only of the p56-LCK kinase. This IL-2-mediated increase in LCK kinase activity was manifested both by increased kinase autophosphorylation and by increased phosphorylation of the exogenous substrate enolase during in vitro kinase assays. Furthermore, immunoblot assays determined that the levels of p56-LCK protein were unaltered by IL-2-treatment, indicating that the measured elevations in LCK kinase activity reflected an increase in the specific activity of this PTK. In TALL-103/2 cells, IL-2 stimulated concentration-dependent increases in p56-LCK activity that displayed rapid and transient kinetics: detectable increases occurred within 1 minute after IL-2 stimulation, peaked at 10 minutes, and declined to baseline levels by 30 minutes. Treatment of TALL-103/2 cells with IL-4 abrogated IL-2-initiated proliferation, but did not inhibit IL-2-mediated activation of p56-LCK.(ABSTRACT TRUNCATED AT 250 WORDS)


Regulation of synovial cell growth: basic fibroblast growth factor synergizes with interleukin 1 beta stimulating phospholipase A2 enzyme activity, phospholipase A2 activating protein production and release of prostaglandin E2 by rheumatoid arthritis synovial cells in culture. Cytokines have been implicated in the regulation of eicosanoid synthesis and synovial cell proliferation. To further define these mechanisms, we have compared the effects of basic fibroblast growth factor and platelet-derived growth factor on cell growth, prostaglandin E2 (PGE2) production and phospholipase A2 enzyme activity in long-term cultures of synovial cells from rheumatoid arthritis (RA) patients capable of proliferating in serum-free medium. Compared with serum-free medium alone, RA synovial cell growth was significantly enhanced by adding either basic fibroblast growth factor (bFGF) or platelet-derived growth factor (PDGF) to the culture medium. Growing RA synovial cells for 14 days in serum-free medium plus bFGF caused them to spontaneously release significant amounts of PGE2, an effect not seen if cells were grown in serum-free medium alone, or serum-free medium plus PDGF. Enhanced release of PGE2 occurred when arachidonic acid was added to bFGF but not PDGF-treated RA synovial cells, suggesting that bFGF increased cyclooxygenase enzyme activity in these cells. Moreover, phospholipase A2 (PLA2) enzyme activity was found to be significantly greater in RA synovial cells grown for 14 days in serum-free medium containing bFGF alone, or bFGF plus interleukin 1 beta (IL-1 beta) compared with cells grown in either serum-free medium alone, or serum-free medium plus PDGF. Similarly, bFGF plus IL-1 beta-stimulated release of PLA2 activating protein, a novel mammalian phospholipase stimulator found in high concentrations in RA synovial fluid.(ABSTRACT TRUNCATED AT 250 WORDS)


Presence of interleukin 10 (IL-10) in the ascites of patients with ovarian and other intra-abdominal cancers. Typically, ovarian cancer remains restricted to the peritoneal cavity. Because of this unique localization, the study of ovarian cancer is particularly suitable for immune analysis and for the development of immunotherapy. Here we report that peritoneal fluid from patients with ovarian or other intra-abdominal cancers contained significantly elevated levels of interleukin 10 (IL-10) (542 +/- 77 pg/ml, N = 35), compared with peritoneal fluid from patients with benign gynecological conditions (34.2 +/- 7.5 pg/ml, N = 63) (P < 0.001). Peritoneal fluid IL-10 levels did not correlate with histology, tumor stage, grade, or prognosis. IL-10 levels were also elevated in the serum of patients with intra-abdominal cancer (1353 +/- 906, N = 8). Established ovarian cancer cell lines (N = 5) did not produce any detectable IL-10. Investigation of the cell surface phenotype of the cells in the peritoneal cavity indicated the presence of significant amounts of activated immune cells. The presence of cytokines such as IL-10 in the peritoneal cavity of ovarian cancer bearing patients could be important in the growth and development of cancer, more specifically, in relation to host immune responsiveness.


The autocrine role of tumor necrosis factor in the proliferation and functional differentiation of human lymphokine-activated T killer cells (T-LAK) in vitro. The autocrine role of tumor necrosis factor alpha (TNF) in the proliferation and functional differentiation of human lymphokine-activated T-killer cells (T-LAK) in vitro was investigated. Human peripheral blood lymphocytes initially stimulated with IL-2 and phytohemagglutinin-P (PHA) for 48 h will proliferate for long periods in vitro in the presence of IL-2. These T-LAK cells have been shown to be 95% CD3 positive. Employing ELISA techniques, greater than 500 pg/ml of TNF was found to be released in the supernatants of these cells during the first 5 days of culture. However, the levels dropped to 100-200 pg/ml by days 7-10. T-LAK cells grown from days 7 to 10 in the presence of IL-2 and rabbit anti-TNF were significantly growth inhibited (up to 23%). The cytolytic activity of T-LAK cells grown from days 0 to 7 in the presence of anti-TNF was also decreased (up to 75%). Phenotypic analysis of these anti-TNF treated T-LAK cells revealed a decrease in CD8 expression (up to 12%) and increase in CD4 expression (up to 27%) when compared with control cells. The data suggest that TNF has a regulatory role in the growth and functional differentiation of these human T-LAK cells.


In-vitro stimulation of TNF-alpha from human whole blood by cell-free supernatants of gram-positive bacteria. Gram-positive bacteria are being recognized increasingly as the cause of shock-like syndromes, clinically indistinguishable from those seen in association with Gram-negative endotoxic shock. Much clinical and experimental data link tumour necrosis factor-alpha (TNF-alpha) with the pathogenesis of endotoxic shock, and a number of studies of individual Gram-positive species have also implicated TNF-alpha. We report here the first systematic study of the ability of cell-free supernatants of common Gram-positive bacteria to induce TNF-alpha from human peripheral blood monocytes in vitro. Almost all the 63 strains were able to induce TNF-alpha, although the levels were substantially lower than those obtained from supernatants of Gram-negative bacteria, used as controls. Streptococcus pneumoniae, S. pyogenes, viridans streptococci and coagulase-negative staphylococci were consistently more active than group B and D streptococci. TNF-alpha induction did not correlate with conventional markers of pathogenicity; amongst strains of Staphylococcus aureus, commensal and blood culture isolates did not induce significantly different amounts of TNF. We conclude that cell-free supernatants of most Gram-positive bacteria are capable of inducing TNF-alpha from human peripheral blood monocytes in vitro, but the significance of this finding remains to be determined.


Cytological evaluation of the effect of Tamoxifen in premenopausal and post-menopausal women with primary breast cancer by analysis of the karyopyknotic indices of vaginal smears. The influence of Tamoxifen on the vaginal epithelium of 33 premenopausal and 99 post-menopausal women with primary advanced breast cancer was investigated. The karyopyknotic index (KPI) values were assessed before starting therapy and at monthly intervals during therapy with Tamoxifen. A decrease in the KPI in menstruating women and a slight but definite increase in KPI values in post-menopausal women were observed.


Well differentiated follicular neoplasms of the thyroid: reproducibility and validity of a 'decision tree' classification based on nucleolar and karyometric features. This study was conducted on fine-needle aspirates of well differentiated follicular neoplasms of the thyroid. A 'decision tree' classification based on the percentage of nucleolated nuclei, percentage of nuclei with two or more nucleoli and mean major nuclear diameter was adopted. We observed that the reproducibility and the validity of the follicular adenoma vs follicular carcinoma discrimination are greater than in the subjective evaluation. Moreover, similar classification results were obtained when measurements were performed either with a fully automated image analysis system or with semiautomatic or manual instrumentation. As for reproducibility of the inter-instrument comparisons, the k statistic values ranged from 0.85 to 1.00 (mean value 0.90, that is, an 'almost perfect' degree of agreement); in the subjective evaluations, the inter-observer comparisons showed values ranging from 0.20 to 0.56 (mean value 0.37, that is, 'fair'). In the decision tree classification, feature value thresholds were selected in order to have specificity of 100% and the predictive value of a positive result (carcinoma) of 100%; accuracy was 87% (range 86-89%), sensitivity 74% (71-79%), the predictive value of a negative result (adenoma) 79% (78-82%). In the subjective evaluation the values were as follows: accuracy 67% (64-71%), sensitivity 57% (50-64%), specificity 77% (71-79%), predictive value of a negative result (adenoma) 64% (61-69%), predictive value of a positive result (carcinoma) 71% (67-75%). The conclusion is that, by using a routine microscope equipped with a micrometer, the preoperative diagnosis of follicular carcinoma from smears can be formulated with a high degree of certainty.


Nucleolar organizer regions in pituitary gland adenomas. Nucleolar organizer regions are DNA segments concerned with the synthesis of ribosomal RNA (rRNA). Some specific proteins related to NORs can be demonstrated by a silver technique and are then referred to as Ag-NORs. The mean number of Ag-NORs per cell has been used as a marker of cell proliferation in recent years and there is some evidence to suggest that Ag-NOR counts can be used to differentiate between normal and neoplastic cells. Paraffin block sections of 42 pituitary gland adenomas and 24 normal adult pituitary glands have been examined using the Ag-NOR staining technique. Touch imprints of nine adenomas and 12 normal adult pituitary glands were also examined using the same Ag-NOR staining technique. Using light microscopy at x2000 magnification, the Ag-NORs were located as black dots in the cell nuclei and the mean number of Ag-NORs per cell was determined. No significant difference was observed between blocked sections and imprints of adenomas or between imprints and paraffin sections of normal glands. However, a significant difference was observed between the mean number of Ag-NORs in pituitary gland adenomas and normal glands in paraffin block sections and touch preparations (P less than 0.001). The modified Ag-NOR technique can be a useful aid in the differential diagnosis between normal pituitary gland tissue and pituitary adenomas, especially during surgical operations.


Leiomyosarcoma of the breast; cytological and histological features, with a review of the literature. This report describes the cytological and histological features of a leiomyosarcoma of the breast. The differential diagnosis of this rare tumour is discussed. Eleven well documented cases of leiomyosarcoma of the breast have been reported previously and details of these are included in this review.


Cytological appearances of a solitary squamous cell papilloma with associated mucous gland adenoma in the lung. Solitary papillomas of the lung are rare. They are usually squamous but mixed squamous cell papilloma and mucous gland adenoma can occur. We report for the first time the cytological findings of a fine needle aspirate from a mixed squamous cell papilloma and mucous gland adenoma from the lung periphery.


Peripheral low-grade mucoepidermoid carcinoma of the lung--needle aspiration cytodiagnosis and histology. Mucoepidermoid carcinoma of the lung is a rare tumour, and is not usually considered in the differential diagnosis of a peripheral lung mass. The cytological and histological features of an intimate admixture of polygonal intermediate cells, well differentiated mucinous and squamous cells, as illustrated in this case report, serve to differentiate a well differentiated mucoepidermoid carcinoma from adenosquamous carcinoma, low grade adenocarcinoma, bronchioloalveolar carcinoma, and benign reactive changes.


A statistical chronicle of tuberculosis in Canada: Part I. From the era of sanatorium treatment to the present. This report marks over 50 years of publication by Statistics Canada of annual reports on tuberculosis statistics. These years have witnessed what has been described as a conquest of tuberculosis in Canada. To quote George Jasper Wherrett in The Miracle of the Empty Beds: One hundred years ago the word consumption (as tuberculosis was then called) struck horror in human hearts. Today, in the western world, it barely evokes any emotion save a too easy surprise that it still exists. This statistical chronicle of tuberculosis in Canada is divided into two parts. Part I: From the Era of Sanatorium Treatment to the Present pulls together data from yellowed-with-age reports on tuberculosis and vital statistics, historical accounts and modern computer files, to document the changes in tuberculosis incidence and mortality over past decades to the present. Part II: Risk Today and Control takes a closer look at those most vulnerable to contracting tuberculosis. It also looks at the future, the need for maintaining and, indeed, strengthening vigilance, and the work yet to be done to eradicate tuberculosis in Canada. The fight against tuberculosis is far from over.


Comparison of granulocyte-macrophage colony stimulating factor and interleukin-1 production from human peripheral blood mononuclear cells as measured by specific radioimmunoassays. Attention has focused on cytokine networks in which gene and protein expression of some cytokines is under the influence of other cytokines. In the present studies, we addressed the relationship between the synthesis of granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-1 (IL-1) in human peripheral blood mononuclear cells (PBMC) stimulated with mitogens. Since bioassays for cytokines are sensitive to more than one of these factors, it was necessary to measure the amounts of IL-1 and GM-CSF independent of bioassays. A specific and sensitive (40 pg/ml) radioimmunoassay (RIA) was developed for human GM-CSF. The sensitivity of the RIA was greater when lysine residues were iodinated with Bolton-Hunter reagent than tyrosine residues using chloramine T. After stimulating PBMC with concanavalin A (Con A), the biological activity of GM-CSF was determined in bone marrow cultures and compared to immunoreactive GM-CSF; GM-CSF levels detected by bioassays and RIAs were highly correlated in two separate sets of experiments (r2 = 0.95 and 0.43). Incubation with Con A for 48 h induced more GM-CSF than stimulation by phytohemagglutinin (PHA) despite the fact that PHA stimulates large amounts of IL-1 alpha; indomethacin had no effect on Con A stimulated synthesis of GM-CSF or IL-1 alpha. In two separate studies, PBMC from 14 donors and a second group of 12 donors were incubated with Con A for 48 h and the total amount of immunoreactive IL-1 alpha and GM-CSF was determined in the same cell cultures. There was no correlation of the amount of either cytokines in these cultures.(ABSTRACT TRUNCATED AT 250 WORDS)


Activation of the systemic production of tumor necrosis factor after exposure to acute stress. Tumor necrosis factor (TNF), which was originally identified as a tumoricidal factor, is now regarded as one of the main regulators of inflammation and various immune systems. Thus it has been considered to be mobilized in case of emergency. However, we assume that TNF and the cytokine network driven by the monokine also function under normal condition for homeostasis of the animal body which is exposed to various kinds of physiological stress. To test this possibility, we exposed C3H/He mice for up to 3 days to five types of acute stress: food deprivation, drinking water deprivation, sleep deprivation, swimming, and physical restraint. After release from the stress, the level of priming for systemic production of TNF was examined using OK-432 (a streptococcal preparation) as a trigger. Priming of TNF production was not observed immediately after 2-day exposure to most of the stressors. Sleep deprivation alone tended to induce a primed state especially when the stress period was lengthened to 3 days. On the other hand, by keeping mice in a normal condition for a 2-day restorative interval after 2-day exposure to the stressors, systemic production of TNF was consistently primed for all the stress examined. The time course of the priming effect was examined in detail for water-deprivation stress. The effect was detected as early as 3 hours after release from stress, was sustained for 2 days, and returned to the basal level by 4 days after the release. Based on these results, we discussed the role of the TNF-driven cytokine circuit in adaptation to stress.


Gender inequalities in care-giving in Canada. In Canada today, as in the past, men and women devote different amounts of time and effort to providing health care to their family and in the broader community. This paper examines "the social distinction between masculinity and femininity" in care-giving. Issues of gender inequality in care-giving have the potential to affect the formal health care system as the burden of caring will increase over the next few decades with the aging of society. This increase in need for care is occurring at a time when primary care providers--women--have additional demand on their time. Canadian society has been facing a series of social, demographic and economic shifts such as a higher divorce rate, two-income families, women's increasing professional commitments and first pregnancies at later ages, these factors may not affect women's willingness to care for others. However women may need support to provide the care. Assuming present trends, increasing need for families to care for elderly relatives may be inevitable. Perhaps society will recognize this need and provide support to those providing informal care. This could take the form of allowing individuals more time to provide care through child care leave, leave to care for parents and job-sharing. Support to those providing informal care might also be facilitated through community support services such as respite care, household maintenance, psychological support to care-givers, support groups, informal networks within a community and consideration of unconventional support methods.


Interleukin-2 and blood brain barrier in cats: pharmacokinetics and tolerance following intrathecal and intravenous administration. Single bolus doses of glycosylated human interleukin-2 (n IL-2) in the range of 2.8 x 10(3) to 2.0 x 10(6) IU/kg were administered to anesthesized cats via the cephalic vein (n = 10) or using suboccipital puncture (n = 8). CSF (cerebrospinal fluid) and blood samples were collected by repeated puncture. The n IL-2 concentration in four cats was determined on the basis of its biologic activity using 3H-thymidine incorporation into human ConA-blasts and by radioimmunoassay. In additional experiments radioactivity was determined in cerebrospinal fluid and serum after intravenous and intrathecal (i.th.) application of 5.8 x 10(3) - 3.2 x 10(3) IU/kg of 14C-acetyl-n IL-2 in regular time intervals. CSF and serum concentration time-profiles show a biexponential decline in the plasma elimination phase with half-lives of 4 min (alpha-phase) and 90 min (beta-phase) after intravenous and 20-120 min (alpha-phase) and 2-16 hours (beta-phase) after intrathecal application. There is a trend towards longer terminal elimination half-lives with increasing doses. Interleukin-2 is able to penetrate the blood brain barrier from the circulation into the cerebrospinal fluid and vice versa. Due to a slow rate of penetration and rapid elimination from blood only traces of n IL-2 (2-8 IU/ml) are detected in CSF after i.v. injection of 2 x 10(6) IU/kg, whereas concentrations between 400 and 1600 IU/ml are maintained in CSF for several hours following i.th. administration of 2-10 x 10(5) IU/kg.(ABSTRACT TRUNCATED AT 250 WORDS)


Mortality differentials between three populations--residents of Scandinavia, Scandinavian immigrants to Canada and Canadian-born residents of Canada, 1979-1985. The study compares the mortality of Canadian residents born in Canada and Scandinavia (Finland, Sweden, Norway, Denmark) to the mortality of the four Scandinavian countries. The study focuses on the mortality experience of anyone who was 35-74 years old during the period 1979-85. Swedish and Norwegian populations both in Scandinavia as well as immigrants to Canada had relatively low mortality from all causes of death. On the other hand, populations in Finland and Denmark had comparatively higher mortality from certain causes of death. Finnish excess mortality from cardiovascular diseases and from external causes of death was present in Finnish living in Scandinavia as well as in Finnish immigrants to Canada. This contrasted with the excess mortality from non-cardiovascular disease in the population of Denmark which was not reflected in the mortality of Danish immigrants to Canada. Finally, the cardiovascular mortality of all Scandinavian-born immigrants to Canada was found to be lower than in their respective countries of origin. The article includes a discussion of possible explanations for these results.


1992 Canadian Cancer Statistics.

1992 Canadian Cancer Statistics. In Canada, it is estimated that in 1992 115,000 new cases of cancer will be diagnosed. This total excludes 47,200 estimated new cases of non-melanoma skin cancer. The number of new cases is increasing by about 3,000 per year due partly to the aging population, improved registration, earlier detection of cancer and real increases in the incidence of some types of cancer. It is estimated that there will be 58,300 cancer deaths in 1992. By 1992, prostate cancer will have overtaken lung cancer as the leading cancer among men in the four western provinces while lung cancer is expected to exceed breast cancer as the leading cause of cancer deaths among women in some provinces, notably British Columbia. In British Columbia, the relative survival rates for most cancers improved between the periods 1970 to 1974 and 1980 to 1984. However, stomach, lung and pancreatic cancers, which have low survival rates, showed little improvement. This article is based on 1992 estimates of cancer incidence and mortality, cancer trends in Canada and relative cancer survival rates in British Columbia, found in Canadian Cancer Statistics 1992. This publication was prepared at Statistics Canada through a collaborative effort involving the Canadian Cancer Society, Health and Welfare Canada and the provincial/territorial cancer registries.


Interleukin-1 and tumour necrosis factor production by human monocytoid cells: study on a single cell level. Human IL-1 beta and TNF alpha production by normal and transformed monocytoid cells was studied using biological assays, cytokine specific ELISA and by immunocytochemical methods on a single cell level. Quiescent human blood monocytes and cultured in vitro transformed human monocytoid cell lines U-937, THP-1 and HL-60 did not contain IL-1 beta and TNF alpha in their cytoplasm. IL-1 beta synthesis and secretion was induced by LPS stimulation in nearly 90% monocytes, 15-20% U-937, 3-5% THP-1 and in no HL-60 cells. Normal human blood monocytes had a more rapid kinetics of IL-1 beta synthesis. IL-1 beta positive cells stained with antibodies to human IL-1 beta appeared at 1-2 hours after LPS application, while in monocytic cell lines only after 4-6 hours. Using immunoperoxidase staining of U-937 cells pulse labelled with 3H-thymidine, it was shown that proliferating cells did not synthetize IL-1 beta. Instead of IL-1 beta, TNF alpha could be induced by LPS in U-937 cells only after preliminary differentiation with PMA. Recombinant IL-1 beta induced a very low level of TNF alpha production in PMA-treated cells. Similarly recombinant TNF alpha alone induced IL-1 beta synthesis only in a few U-937 cells.


The roles of IL-4, TGF-beta and LPS in IgA switching. CH12.LX B cells have been used as a lymphoma model of MHC restricted, antigen-dependent B cell differentiation. These B cells express surface IgM and secrete IgM. Most recently we have demonstrated that CH12.LX is a model of cytokine driven IgA differentiation. Recently, transforming growth factor beta (TGF-beta) has been shown to be a probable switch factor for IgA in LPS-stimulated mouse lymphocytes, therefore we chose CH12.LX B cells to study the effect of IL-4, TGF-beta and LPS in IgA isotype switching. Adding TGF-beta to the monoclonal cell line CH12.LX results in induction of mIgA expression but no enhancement of IgA secretion similar to the effect of IL-4. The addition of LPS serves as a non-specific stimulus to enhance the secretion of the expressed immunoglobulin, but has no IgA specific activity of its own. IL-4 and TGF-beta together are synergistic for mIgA expression. Pretreatment studies show that TGF-beta added after IL-4 is the same as TGF-beta alone whereas the converse is the same as adding both cytokines together. TGF-beta acts by increasing the steady state levels of alpha message, whereas northern analysis indicates that IL-4 does not induce alpha message the way TGF-beta does. These data confirm that TGF-beta by itself is an isotype switch factor for IgA. In addition, IL-4 and TGF-beta cause mIgA expression through different mechanisms. CH12.LX B cells serve as a valuable model to study the role of multiple signals required for mIgA expression and IgA secretion.


Inhibition of morphine dependence by a lipopolysaccharide from Pantoea agglomerans. A lipopolysaccharide from Pantoea agglomerans (LPSp) was purified and examined for relief of morphine dependence by observing its inhibition of the jumping of mice on naloxone-precipitate withdrawal. Administration of LPSp either intravenously or intradermally showed marked inhibition of the jumping. Beta-endorphin in mouse serum and brain tissue were recognized to be in synchrony with the time course of the relief. Administration of TNF-alpha gave similar effect, suggesting that LPSp induces a cytokine cascade to produce endogenous TNF followed by ACTH/beta-LPH gene products and beta-endorphin. The effect of LPSp was better than that of LPS from E. coli or Bordetella pertussis, and thus is considered to be applicable for clinical use.


Retrospective study correlating clinical infectious history and peripheral blood T-cell subpopulations in cancer, GvH and HIV+ patients. The CD4+ CD8- inducer helper cell and the CD4- CD8+ cytotoxic/suppressor cell absolute numbers were measured in the peripheral blood of patients with various pathological conditions: with leukemia-lymphomas or solid tumors, patients with bone marrow grafts suffering from GvH, HIV-1 asymptomatic carriers, ARC and AIDS patients. The study was carried out during observation periods when they were not suffering from opportunistic infections and were untreated. In all the groups a decrease of the CD4+ CD8- cell absolute number was observed. In the leukemia-lymphoma and solid tumor bearing patients the CD4- CD8+ absolute value was lower than normal, while in the GvH- and HIV-infected patients, it was significantly higher. The clinical follow-up of each group indicates that GvH, ARC and AIDS patients developed infection in 40-68% of the cases, ie the only groups at risk of infection are those in which the CD4- CD8+ absolute values are high: we suggest that the balance CD4+ versus CD8+ should be considered rather the absolute CD4+ when discussing appropriate use of immuno-regulators.


Analysis of purine nucleotides in lymphocytes from healthy subjects and AIDS patients. The most important purine nucleotides (NAD, AMP, IMP, GMP, XMP, ADP, ATP, GDP, GTP) were analyzed by HPLC in the lymphocytes of healthy subjects and HIV-1 seropositive patients at different stages of the disease (ARC-AIDS). Several differences, which focus attention on the behaviour of purine nucleotide metabolism in the lymphocytes of these patients, were observed.


The role of drugs in the origin of AIDS. It is proposed that the new American and European AIDS epidemics are caused by recreational and anti-HIV drugs rather than by human immunodeficiency virus (HIV). Chronologically, the AIDS epidemic in the 1980s followed a massive escalation in the consumption of recreational drugs that started in the 1960s and 70s. Epidemiologically, both epidemics derive about 80% of their victims from the same groups of 20-44 year-olds, of which 90% are males. In America 32% of these are intravenous drug users and their children, about 60% are male homosexuals who are long-term users of oral aphrodisiac drugs and an unknown percentage are prescribed the cytotoxic DNA chain terminator AZT, as inhibitor of HIV. Direct evidence indicates that these drugs are necessary for HIV-positives and sufficient for HIV-negatives to develop AIDS diseases. The drug-AIDS hypothesis predicts correctly that: (i) AIDS is new in the US, because the drug epidemic is new, while the HIV epidemic is old--fixed at a constant 1 million Americans since 1985; (ii) despite an increase in venereal diseases, AIDS remains restricted to long-term drug users and small groups with clinical deficiencies; (iii) over 72% of AIDS occurs in 20-44 year-old males, because they make up over 80% of hard psychoactive drug use; (iv) distinct AIDS diseases correlate with the use of distinct drugs, eg Kaposi's sarcoma with nitrite inhalants, tuberculosis with intravenous drugs, and leukopenia, anemia, and nausea with AZT; (v) AIDS diseases are only acquired after long-term drug consumption, rather than after single contacts as the virus-hypothesis predicts. The drug hypothesis can be tested epidemiologically and experimentally in animals. It predicts that most AIDS can be prevented by stopping the consumption of drugs, and provides a rational basis for therapy.


Serum bone alkaline phosphatase and CA 549 in breast cancer with bone metastases. A monoclonal radioimmunometric assay for bone alkaline phosphatase (BAP) developed by Hybritech, USA, with an upper limit of normal of 40 U/l, was examined in 125 patients with breast cancer. Eleven patients who remained tumour free for 5-6 years had small intra-individual variations of BAP. The median value in 33 patients with multiple bone metastases of 60 U/l was elevated when compared with that in 40 patients with no evidence of metastases (22 U/l) and 34 U/l in 16 with limited bone disease (1-2 hot spots). By contrast, only 2 out of 25 patients with extensive local recurrence, lung, or hepatic metastases, without bone involvement showed an increase of BAP (< 200 U/l). The BAP levels were compared to total alkaline phosphatase (TAP), the breast cancer marker CA 549 (HybriBREScan). Longitudinal studies of 15 patients with bony metastases showed that TAP and BAP were well correlated only when the TAP was elevated; CA 549 and BAP could vary independently. The main use of BAP in patients with bone metastases appears to be an aid to the monitoring of treatment; however, it is not significantly raised in limited bone metastases.


Serum erythropoietin levels in hemodialysed patients after administration of recombinant human erythropoietin. In anemic patients on regular hemodialysis (HD), correction of anemia with recombinant human erythropoietin (rHuEpo) administered intravenously (iv) or subcutaneously (sc) was followed over a 2-month period. Monitoring serum Epo post-dose concentrations after the first iv rHuEpo injection and following another regular injection after 2 months of therapy with rHuEpo iv in 9 patients showed that the Epo elimination half-life was reduced from 7.48 h to 4.68 h. In the same patients the initially low percentage of erythroblasts and mature erythroid progenitors increased during 2 months of rHuEpo therapy. Because Epo molecules bound to Epo receptors are internalized in target cells we suggest that the expansion of the Epo responsive cell pool could explain the shorted Epo elimination time after 2 months of rHuEpo treatment. By monitoring serum Epo concentration following sc rHuEpo injection in 7 HD patients it was found that the modest increase in serum Epo levels (30-60 mU/ml) was sufficient to correct anemia.


Levels and variability of purine nucleotides in normal human lymphocytes. Anion-exchange, high performance liquid chromatography was used to determine purine nucleotides in lymphocytes of healthy males and females of various ages. We observed a considerable dispersion of values which were unrelated to age or sex, possibly linked to various states of activation of circulating lymphocytes and to other unknown factors.


TSH binding site structures in human eye muscle fractions identified by using covalent-crosslinking. 125I-labelled human TSH was crosslinked to the human thyroid and extraocular eye muscle membrane and cytosol fractions (which were obtained by centrifugation). Studying crosslinking of 125I-labelled TSH to the thyroid fractions, TSH binding sites' structures were demonstrated on the eye muscle membranes and in the cytosol fractions. The binding of 125I-labelled TSH was inhibited by the addition of 120 mIU/mL of unlabelled TSH (and not with 12 mIU/mL) which confirmed the presence of TSH binding sites structures (MW about 66,000 Da) on the eye muscle membrane and in its cytosol. Adding purified IgG fractions from the sera from controls and Graves' disease (with high titer of antibodies against TSH receptor) to the thyroid and eye muscle membranes and cytosol fractions, the binding of 125I-labelled human TSH was inhibited by molecular weight of about 66,000 Da in the cytosol fractions. The affinity constant of the binding sites in the human eye muscle cytosol and the number of TSH receptors were found to be 146 x 10(9) M-1 and 9.8 x 10(10) molecules/mg/mL by Scatchard analysis, respectively.


Current problems in organ transplantation. Organ transplantation has evolved over the past 30 years, although 'new' and 'old' problems remain unsolved, which from a personal point of view, might be summarized as: i) the transfusion effect; ii) HLA matching and pre-graft sensitization of the potential recipient; iii) immunosuppressive drugs; iv) the pathogenesis of chronic rejection; v) infections; vi) de novo cancers. The aim is to attain a state of specific immunological tolerance without the use of immunosuppressive drugs.


Current status of allogeneic bone marrow transplantation. Use of allogeneic bone marrow transplants continues to increase. During the 36-year period between 1955 and 1990, more than 33,000 patients received allogeneic bone marrow transplants; more than 45% of these were performed during the 3 years 1988-1990. Transplants are effective therapy for leukemia and other hematologic diseases. It is widely considered that transplants are the treatment of choice for aplastic anemia and chronic myelogenous leukemia, those who fail conventional therapy for acute leukemia and a variety of genetic, metabolic and immune deficiency disorders. Successful application of bone marrow transplantation is limited by complications such as graft failure, graft versus host disease GVHD and interstitial pneumonia and, until recently, the requirement for an HLA-identical sibling donor. In the past few years, an increasing number of transplants were performed using unrelated or HLA-partially matched related donors with some success. Development of post-transplant complications can often be predicted by risk factor assessment. In this report, current data from the IBMTR are summarized and several risk factors affecting outcome identified.


Pancreas and islet transplantation in man. The results of pancreas transplantation have greatly improved, the overall patient and graft 1-year survival rates now being 89 and 62%, respectively. A technically successful graft ensures a near-normal glucose metabolism in most cases, and improves the patient's quality of life. However, pancreas transplantation is not a life-saving procedure and because of the necessary permanent immunosuppression it is usually performed in patients in whom a kidney transplant is needed or has been previously established. In such patients the other diabetic chronic complications are often advanced and limit the potential benefit of pancreas transplantation, but it seems premature to extend the indications to early stage diabetes. Islet transplantation has many potential advantages, mainly the possibilities of immune alteration and immune protection of the transplant that could allow transplantation to be performed without immunosuppression and the use of xenogenic tissue. Major limiting factors are the high numbers of islets necessary to ensure insulin independence and the low yield of islet isolation from adult pancreas. Encouraging, albeit preliminary results have been recently reported in man.


Liver transplantation: the challenges of the 1990s. An enormous increase in liver transplantation has been observed over the last decade since it now represents a suitable therapeutic option for patients with end-stage liver disease. The overall one-year survival rate is about 75% for adults and 85% for children, when fulminant hepatic failure and malignancies are excluded. Such improvements in both survival and quality of life are due to many concurrent factors: better timing and selection; development of the UW solution for liver preservation; improvement in operative management including surgical technique, veno-venous bypass and cell-saver; progress in intensive care management of immunosuppressed patients. Nevertheless, the increasing demand for livers is now confronting the transplant teams with organ shortage, for which the introduction of graft reduction, hepatic biparition and living-related donation will contribute to alleviate the scarcity of donors. As a consequence of the increasing number of long-term survivors, greater efforts are now being directed towards the long-term outcome after liver transplantation: disease recurrence, the need for permanent immunosuppression and the quality of rehabilitation will become the challenges of the 1990s before reaching the next step towards multiple organ transplantation.


Allogenic recognition in 1992.

Allogenic recognition in 1992. Many new data have been obtained in the last 4 years concerning the structure and functions of major histocompatibility complex (MHC) molecules. Structural data are summarized and the functions of MHC molecules in the presentation of peptides to T cells are described. The high selectivity of peptides binding to MHC molecules is discussed. The negative and positive selection of T cells in the thymus is described and the notion of repertoire introduced. The consequences of these new data on the understanding of H2 restriction and alloreactivity are described. The four potential types of alloreactivity are defined: i) house keeping gene (HKG) peptides bound to allogenic MHC molecules; ii) allogenic peptides (derived from allogenic MHC molecules) bound to allogenic MHC molecules; iii) empty allogenic MHC molecules; iv) allogenic peptides bound to autologous MHC molecules. In fact, the allogenic response is mostly directed toward HKG peptides bound to the allogenic MHC molecules of the graft cells (type 1). The potential role of type four alloreactivity in rejection is discussed.


Endoscopic ultrasonography in colorectal diseases. Since new flexible high-frequency ultrasound endoscopes are now available, the use of this technique in colorectal disease has been determined. Its role in the preoperative staging of rectal cancer, and in follow-up after surgery has been established, but its use in cases of anal cancer and in non-neoplastic rectal diseases still has to be demonstrated more precisely.


Surgical endoscopy in thoracic surgery.

Surgical endoscopy in thoracic surgery. From November 1990 to April 1992, 32 patients were operated on by video thoracoscopic surgery (VTS). Included were 22 males and 10 females, mean age 47.6 years. VTS has been used therapeutically on 25 occasions: 20 spontaneous pneumothoraxes; two recurrent pleuritis; two cysts; one mediastinal; one pulmonary; and one thoracic sympathectomy. VTS was also used diagnostically seven times: five lung biopsies and two mediastinal lymph node biopsies. It was necessary to perform a mini-thoracotomy in one patient and proceed to immediate thoracotomy in three patients. There were no deaths in this series, the morbidity was two patients with collapsed lungs, one of which required drainage. VTS must be performed under standard thoracic surgical conditions: selective intubation, and fully equipped to make an immediate thoracotomy. The advantages of VTS are aesthetic and functional, the post-operative pain is reduced in intensity and duration. At present, VTS is indicated for the treatment of spontaneous pneumothorax, the assessment and biopsy of mediastinal lymph node and the excision of some lung lesions. Improvements in the apparatus should lead to a broadening of these indications in the future.


Non-surgical management of bile duct stones. Endoscopic sphincterotomy with stone extraction is the non-surgical method of choice for treatment of choledocholithiasis in patients unfit for surgery or with previous cholecystectomy. Its success rate is 85-90%. Many adjunctive methods have been developed to increase the clearance rate after initial failure and are reviewed in this paper. Collaboration among the surgeon, endoscopist and radiologist offers the patient a high opportunity for successful clearance of common bile duct (CBD) stones with the least morbidity and mortality. The application of endoscopic sphincterotomy combined with laparoscopic cholecystectomy to younger patients is now debated.


Immunogenicity of combined anti-HIV and anti-suppressive vaccine preparations. HIV-1 antigens generate in man both a humoral and cellular immune reaction. However, in ARC/AIDS patients, the cellular response is inhibited by HIV-1 which induces an antiproliferative (suppressive) effect on activated T cells. To overcome this inhibition and up-regulate the cellular response, we designed a new vaccine strategy directed both against HIV-1 and immunosuppression and we used an immunizing preparation composed of HIV-1 antigens combined with immunoregulatory peptides prepared in a biologically inactivated but immunogenic form. In mice, this preparation induced anti-HIV-1 antibodies and a cell-mediated cytotoxicity directed against H2 restricted cells carrying HIV-1 antigens.


Effect of pinaverium bromide on jejunal motility and colonic transit time in healthy humans. Pinaverium bromide is a specific calcium channel blocker used in the treatment of irritable bowel syndrome (IBS) for its spasmolytic activity. The aim of the present study was to evaluate the effect of orally administered pinaverium bromide on jejunal motility and total and segmental colonic transit time in control subjects. Gastrointestinal studies were performed in 10 healthy volunteers (30 +/- 3 years), before and after a treatment phase of 14 days (150 mg/d). Jejunal motility was measured by prolonged manometry (14 h) and colonic transit time by a multiple ingestion, single marker technique. No significant modification of phase III of the migrating motor complexes was demonstrated. On the contrary, a significant (p < 0.01) but weak decrease of the frequency of contraction was found. Unlike previous studies, no decrease of total or segmental colonic transit time was demonstrated.


Minocycline and benign intracranial hypertension. A case is reported of a 16-year-old girl who developed benign intracranial hypertension, with severe bilateral papilledema after minocycline therapy. A lumboperitoneal bypass was carried out in view of the ophthalmologic signs and the pressure of cerebrospinal fluid.


Displacement of rifampicin bound to serum proteins by addition of levamisole. We have studied, by ultrafiltration, the interactions between rifampicin (15 and 30 microM) and levamisole (7 microM) since both drugs may be associated for the treatment of brucellosis. We can observe a statistically significant increase in the free plasmatic fraction of rifampicin at the studied concentration of levamisole, which indicated that levamisole reduced rifampicin bound to proteins (290 and 250%, respectively).


Comparative bioavailability and steady state fluctuations of Tegretol commercial and carbamazepine OROS tablets in adult and pediatric epileptic patients. The comparative bioavailability and steady state fluctuations resulting from the administration of Tegretol 200 mg commercial tablets and carbamazepine OROS controlled delivery tablets were investigated in 22 adult and 12 pediatric epileptic patients. Tegretol commercial tablets were dosed according to previously established clinical regimens of 400 to 2000 mg daily doses divided into four equal or unequal intervals. Carbamazepine OROS was dosed every 12 h at the same corresponding daily dose. Comparisons of the pharmacokinetic parameters AUC, Cmax, Cmin, and tmax at steady state for the two dosage forms demonstrated definitively the bioequivalence of carbamazepine OROS with Tegretol commercial tablet over a 24-h treatment interval.


Applicability of teicoplanin dosage adjustment guidelines for renally impaired patients over the range of 3 to 30 mg kg-1. The pharmacokinetics of teicoplanin were investigated in 13 subjects with various degrees of renal impairment using a randomized two-period crossover design; 11 subjects completed both periods. Doses of 3 and 30 mg kg-1 were administered as single dose, 60-min constant rate intravenous infusions. Blood samples were obtained over 28 days and urine was collected over 48 h. Serum and urine were analyzed using a microbiological assay. As previously observed in studies conducted in renally impaired subjects, teicoplanin total and renal clearance significantly decreased with decreasing creatinine clearance (p < 0.0001). However, for these parameters, no differences between doses were observed. Dosage adjustment guidelines for renally impaired patients are usually developed using the ratio of total clearance in renally impaired patients to the total clearance in patients with normal renal function. Since no dose-related differences existed in the relationship between teicoplanin total clearance and creatinine clearance, initial dosage adjustment guidelines for renally impaired patients developed at 3 or 30 mg kg-1 are applicable over the range of 3 to 30 mg kg-1.


Disposition kinetics of 7,12-dimethylbenz(a)anthracene in rats. One of the most potent carcinogens is 7,12-dimethylbenz(a)anthracene (7,12-DMBA), which is used routinely to conduct studies to evaluate carcinogen inhibitors. Its pharmacokinetics have not been reported in the literature. In view of its significant effects on drug metabolizing enzymes and clearance mechanisms, it is important to know its disposition characteristics. In this study, we monitored the disposition characteristics of 7,12-DMBA in rats as a function of dose range commonly used in carcinogenesis studies. A mean residence time of 40-55 min was observed; the total body clearance ranged from 8-13 l kg-1. No effect of dose was observed on the pharmacokinetic parameters. This suggests that the dose-dependent effects of 7,12-DMBA carcinogenesis are related to its transient disposition characteristics.


Input rate-dependent stereoselective pharmacokinetics: enantiomeric oral bioavailability and blood concentration ratios after constant oral input. A pharmacokinetic model and relevant equations were used to simulate the blood concentration ratio (Cratio) and oral bioavailability ratio (Fratio) of the two enantiomers of model racemic drugs after different oral input rates. The simulations were carried out for six metabolically eliminated racemic drugs with regard to differences between the two enantiomers in their metabolic maximum velocity (Vmax) and/or Michaelis-Menten constant (Km). Both Cratio and Fratio values were dependent on the oral input rate of the drugs, with the maximum sensitivity observed for input rates close to the Vmax of the enantiomers. However, at input rates substantially lower or higher than Vmax, the dependence of ratios to input rate was minimal. The profile of dependence of Cratio and Fratio on the input rate differed for the various modeled drugs and, in one case, input rate alteration lead to a reversal in the stereoselectivity of the ratios. Relevance of these findings with regard to alterations in the dose and/or formulation of racemic drugs is discussed.