A multiplex inhalation platform to model in situ like aerosol delivery in a breathing lung-on-chip

Prolonged exposure to environmental respirable toxicants can lead to the development and worsening of severe respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and fibrosis. The limited number of FDA-approved inhaled drugs for these serious lung conditions has led to a shift from in vivo towards the use of alternative in vitro human-relevant models to better predict the toxicity of inhaled particles in preclinical research. While there are several inhalation exposure models for the upper airways, the fragile and dynamic nature of the alveolar microenvironment has limited the development of reproducible exposure models for the distal lung. Here, we present a mechanistic approach using a new generation of exposure systems, the Cloud α AX12. This novel in vitro inhalation tool consists of a cloud-based exposure chamber (VITROCELL) that integrates the breathing ^AXLung-on-chip system (AlveoliX). The ultrathin and porous membrane of the AX12 plate was used to create a complex multicellular model that enables key physiological culture conditions: the air-liquid interface (ALI) and the three-dimensional cyclic stretch (CS). Human-relevant cellular models were established for a) the distal alveolar-capillary interface using primary cell-derived immortalized alveolar epithelial cells (^AXiAECs), macrophages (THP-1) and endothelial (HLMVEC) cells, and b) the upper-airways using Calu3 cells. Primary human alveolar epithelial cells (^AXhAEpCs) were used to validate the toxicity results obtained from the immortalized cell lines. To mimic in vivo relevant aerosol exposures with the Cloud α AX12, three different models were established using: a) titanium dioxide (TiO2) and zinc oxide nanoparticles b) polyhexamethylene guanidine a toxic chemical and c) an anti-inflammatory inhaled corticosteroid, fluticasone propionate (FL). Our results suggest an important synergistic effect on the air-blood barrier sensitivity, cytotoxicity and inflammation, when air-liquid interface and cyclic stretch culture conditions are combined. To the best of our knowledge, this is the first time that an in vitro inhalation exposure system for the distal lung has been described with a breathing lung-on-chip technology. The Cloud α AX12 model thus represents a state-of-the-art pre-clinical tool to study inhalation toxicity risks, drug safety and efficacy.

Reaction microscope for investigating ionization dynamics of weakly bound alkali dimers

We report on the implementation of a far-off-resonant, optical dipole force trap in a reaction microscope combined with a magneto-optical trap. Kinematically complete multi-photon ionization experiments were performed on optically trapped ⁶Li atoms and photo-associated ⁶Li₂ molecules in their highest vibrational state. The apparatus allows us to distinguish different ionization mechanisms related to the presence of the IR field of the optical dipole trap that can occur during ionization of ⁶Li and ⁶Li₂ in strong fields. In a series of proof-of-principle experiments, we detect weakly bound dimers via three-photon ionization with femtosecond pulses (τ = 30 fs) at a central wavelength of 780 nm and measure directly the momenta of the photoelectrons in coincidence with recoil ions.

Probing Electron Spin Resonance in Monolayer Graphene

The precise value of the g factor in graphene is of fundamental interest for all spin-related properties and their application. We investigate monolayer graphene on a Si/SiO_{2} substrate by resistively detected electron spin resonance. Surprisingly, the magnetic moment and corresponding g factor of 1.952±0.002 is insensitive to charge carrier type, concentration, and mobility.

Two-center interferences in dielectronic transitions in H2(+) + He collisions

Molecular two-center interferences in a collision induced excitation of H2(+) projectile ions, with simultaneous ionization of helium target atoms, are investigated in a kinematically complete experiment. In the process under investigation, the helium atom is singly ionized and simultaneously the molecular hydrogen ion is dissociated. Different collision mechanisms are identified and interference fringes emerging from a correlated first-order mechanism and from an independent second-order process are observed.

Strong molecular alignment dependence of H2 electron impact ionization dynamics

Low-energy (E(0) = 54 eV) electron impact single ionization of molecular hydrogen (H(2)) has been investigated as a function of molecular alignment in order to benchmark recent theoretical predictions [Colgan et al., Phys. Rev. Lett. 101, 233201 (2008) and Al-Hagan et al., Nature Phys. 5, 59 (2009)]. In contrast to any previous work, we observe distinct alignment dependence of the (e,2e) cross sections in the perpendicular plane in good overall agreement with results from time-dependent close-coupling calculations. The cross section behavior can be consistently explained by a rescattering of the ejected electron in the molecular potential resulting in an effective focusing along the molecular axis.

Controlling two-electron threshold dynamics in double photoionization of lithium by initial-state preparation

Double photoionization (DPI) and ionization-excitation (IE) of Li(2s) and Li(2p), state-prepared and aligned in a magneto-optical trap, were explored in a reaction microscope at the free-electron laser in Hamburg (FLASH). From 6 to 12 eV above threshold (homega = 85, 91 eV), total as well as differential DPI cross sections were observed to critically depend on the initial state and, in particular, on the alignment of the 2p orbital with respect to the VUV-light polarization, whereas no effect is seen for IE. The alignment sensitivity is traced back to dynamical electron correlation at threshold.

A subnanosecond pulsed ion source for micrometer focused ion beams

A new, compact design of an ion source delivers nanosecond pulsed ion beams with low emittance, which can be focused to micrometer size. By using a high-power, 25 fs laser pulse focused into a gas region of 10(-6) mbar, ions at very low temperatures are produced in the small laser focal volume of 5 mum diameter by 20 mum length through multiphoton ionization. These ions are created in a cold environment, not in a hot plasma, and, since the ionization process itself does not significantly heat them, have as a result essentially room temperature. The generated ion pulse, up to several thousand ions per pulse, is extracted from the source volume with ion optical elements that have been carefully designed by simulation calculations. Externally triggered, its subnanosecond duration and even smaller time jitter allow it to be superimposed with other pulsed particle or laser beams. It therefore can be combined with any type of collision experiment where the size and the time structure of the projectile beam crucially affect the achievable experimental resolution.

The treatment of chronic hepatitis C in HIV-infected patients: a meta-analysis

OBJECTIVE

Hepatitis C virus (HCV) disease progression appears to be accelerated in patients coinfected with HIV. The impact of HCV on coinfected patients is being realized as patients are now living longer. The objective of our study was to further elucidate incremental improvement and safety concerns with combinations of pegylated interferon (peginterferon), interferon and ribavirin based on data obtained from prospective randomized controlled trials.

METHODS

A search of MEDLINE and the Cochrane database for material published between 1966 and 29 August 2005 and a hand search of abstracts from national meetings held between 2001 and August 2005 were performed. Trials comparing the use of peginterferon plus ribavirin vs peginterferon or interferon plus ribavirin were assessed.

RESULTS

In six randomized controlled trials, 1756 patients were randomized. Sustained virological response was greater for patients treated with peginterferon plus ribavirin compared with patients treated with interferon plus ribavirin [odds ratio (OR) 3.00; 95% confidence interval (CI) 2.27-3.96]. This increased sustained virological response with peginterferon and ribavirin was found for patients with HCV genotype 1 or 4 (OR 4.40; 95% CI 2.75-7.03) and genotype 2 or 3 (OR 2.56; 95% CI 1.71-3.85). Sustained virological responses were also higher with peginterferon and ribavirin as compared with peginterferon monotherapy (OR 2.60; 95% CI 1.84-3.67). Severe adverse effects (OR 1.09; 95% CI 0.74-1.4) and withdrawal rates (OR 0.97; 95% CI 0.75-1.25) were similar between patients treated with peginterferon plus ribavirin and patients treated with interferon plus ribavirin.

CONCLUSIONS

Patients with chronic HCV/HIV coinfection have a greater likelihood of achieving a sustained virological response with peginterferon plus ribavirin. The likelihoods of serious adverse effects and study withdrawal were similar.

Few-photon multiple ionization of ne and ar by strong free-electron-laser pulses

Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of Ne2+ production reveals the dominance of nonsequential two-photon double ionization at intensities of I<6x10(12) W/cm2 and significant contributions of three-photon ionization as I increases. Ne2+ recoil-ion-momentum distributions suggest that two electrons absorbing "instantaneously" two photons are ejected most likely into opposite hemispheres with similar energies.

(e,3e) on helium at low impact energy: the strongly correlated three-electron continuum

Double ionization of the helium atom by slow electron impact (E(0)=106 eV) is studied in a kinematically complete experiment. Because of a low excess energy E(exc)=27 eV above the double ionization threshold, a strongly correlated three-electron continuum is realized. This is demonstrated by measuring and calculating the fully differential cross sections for equal energy sharing of the final-state electrons. While the electron emission is dominated by a strong Coulomb repulsion, also signatures of more complex dynamics of the full four-body system are identified.

[Left flank tumor of fluctuating size in a 5-week-old boy: perirenal urinoma caused by urethral valves]

BACKGROUND

Flank swelling and pseudotumors of the kidney are unusual manifestations of obstructive uropathies in small children. Our case illustrates typical problems and briefly reviews management options.

CASE REPORT

A 5-week-old boy presented with a large, palpable urinoma due to posterior urethral valves. Sonography and voiding cystourethrogram led to the diagnosis and immediate suprapubic transcutaneous urinary diversion was performed. However, the urinoma did not resolve. Thus, in addition to suprapubic urinary diversion, indirect drainage - instead of percutaneous puncture - was performed by retrograde insertion of a double-J catheter. Urethral valves were resected 4 weeks later and follow-up demonstrated an uneventful further development with normal renal function as assessed by regular ultrasound studies, a repeat cystourethrogram and a renal scan.

CONCLUSION

Perirenal urinomas may be the first symptom in patients with posterior urethral valves. Drainage via double-J stenting offers a promising alternative to percutaneous puncture. A renoprotective "pop-off" mechanism by which intrarenal pressure may be relieved is discussed.

Three-dimensional images for electron-impact single ionization of He: complete and comprehensive (e, 2e) benchmark data

Comprehensive fully differential cross sections for electron emission into all three spatial dimensions are presented for 1 keV and 102 eV electron-impact single ionization of helium using an advanced reaction microscope. Surprising out-of-plane contributions, traced back to an interference term in a perturbation expansion by comparison with ion-impact data, severely challenge theoretical models that accurately predict coplanar emission. The data represent the ultimate benchmark for recently developed exact theoretical descriptions of the most fundamental three-body quantum problems.

Triple coincidence (e,gamma2e) experiment for simultaneous electron impact ionization excitation of helium

Simultaneous ionization and excitation of helium atoms by 500 eV electron impact is observed by a triple coincidence of an ionized slow electron, the recoiling He+ ion, and the radiated vacuum ultraviolet photon (lambda< or =30.4 nm). Kinematically complete differential cross sections are presented for the He+(2p)2P final ionic state, demonstrating the feasibility of a quantum mechanically complete experiment. The experimental data are compared to predictions from state-of-the-art numerical calculations. For large momentum transfers, a first-order treatment of the projectile-target interaction can reproduce the experimental angular dependence, but a second-order treatment is required to obtain consistent magnitudes.

Electron impact ionization in the presence of a laser field: a kinematically complete (ngammae,2e) experiment

Single ionization of He by 1 keV electron impact in the presence of an intense (I=4 x 10(12) W/cm(2)) laser field (lambda=1064 nm) has been explored in a kinematically complete experiment using a reaction microscope. Distinct differences in the singly to fully differential cross sections compared to the field-free situation are observed which cannot be explained by a first-order quantum calculation. Major features, such as the number of photons exchanged and the modification of the energy spectrum of emitted electrons, can be understood qualitatively within a simple classical model.

Breakup of H2 in singly ionizing collisions with fast protons: channel-selective low-energy electron spectra

Dissociative as well as nondissociative single ionization of H2 by 6 MeV proton impact has been studied in a kinematically complete experiment by measuring the momentum vectors of the electron and the H+ fragment or the H+2 target ion, respectively. For the two ionization pathways, the electron spectra reveal the role of autoionization of the doubly and singly excited states of H2. The latter explicitly involve the coupling between the electronic and the nuclear motion of the molecule. This is a clear manifestation of a breakdown of the Born-Oppenheimer approximation.

Tumorigenesis by adenovirus type 12 in newborn Syrian hamsters

Ad12 oncogenesis in hamsters has been studied in detail to provide the following new data in this tumor model. Cells in the Ad12-induced tumors, often thought to be of neuronal origin, actually exhibit mesenchymal and neuronal characteristics and are probably of an undifferentiated derivation. Their intraperitoneal spread upon intramuscular injection of Ad12 adds another important new aspect. Differences in the integration patterns among the tumors suggest clonal origins from individual transformation events. Ad12 gene expression in the tumors is determined, at least in part, by the patterns of DNA methylation imprinted de novo upon the integrated Ad12 genomes. Differential Ad12 gene expression patterns, which have previously not been described in tumors, are an important parameter in Ad12 oncogenesis. The availability of cellular DNA arrays has opened up unprecedented possibilities to document changes in cellular transcription patterns, particularly of cancer-specific genes. These patterns exhibit differences and similarities among the different Ad12-induced tumors. Among the cellular genes, which are expressed in the Ad12-induced tumors, many are cancer-specific. We pursue the hypothesis that these alterations in cellular transcription patterns as a consequence of viral DNA integration and expression play an essential role in Ad12 oncogenesis.

Rescattering of ultralow-energy electrons for single ionization of Ne in the tunneling regime

Electron emission for single ionization of Ne by 25 fs, 1.0 PW/cm(2) laser pulses at 800 nm has been investigated in a kinematically complete experiment using a "reaction microscope." Mapping the complete final state momentum space with high resolution, a distinct local minimum is observed at P(e parallel )=0, where P(e parallel ) is the electron momentum parallel to the laser polarization. Whereas tunneling theory predicts a maximum at zero momentum, our findings are in good agreement with recent semiclassical predictions which were interpreted to be due to "recollision."

Projectile-charge sign dependence of four-particle dynamics in helium double ionization

Double ionization of helium by 6 MeV proton impact has been explored in a kinematically complete experiment using a "reaction microscope." For the first time, fully differential cross sections for positively charged projectiles have been obtained and compared with data from 2 keV electron impact. The significant differences observed in the angular distribution of the ejected electrons are attributed to the charge sign of the projectile, resulting in different dynamics of the four-particle Coulomb system, which is not considered in the first Born approximation.

Ovicide-induced serosa degeneration and its impact on embryonic development in Manduca sexta (Insecta: Lepidoptera)

Eggs of Manduca sexta treated with the ovicide Ov. 165049 turn orange, and the embryos later die. The orange pigmentation is at first confined to the serosa, and is accompanied by pathological changes of serosal cells. Lipid vesicles aggregate and spindle-shaped electron-lucent vesicles-normally forming a single layer below the apical cell surface-greatly accumulate. The mitochondria swell considerably, and their matrices become electron-lucent. Subsequently, the serosal cells develop additional features of necrosis. They form many autophagic vacuoles which contain mostly degradating mitochondria, but also segregated rough endoplasmic reticulum (rER) and glycogen granules. The whole cytoplasm vesiculates, and the cells shrink considerably. The nuclei become less irregular in shape, the chromatin disperses rather evenly whereas the nucleoli persist. Neither chromatin condensation nor the production of apoptotic bodies was observed-further evidence, that the serosal cells die by necrosis rather than apoptosis. At some stage of development the damaged serosa ruptures, retracts from the embryo and forms a sphere beneath it. It is only after the rupture of the serosa, that the embryo also turns orange and disintegrates rapidly. This shows impressively the protective function which the serosa plays for the embryo. Our physiological tests indicate, that the orange pigmentation of the serosa induced by the ovicide results from a disturbance of the tryptophan/ommochrome pathway serving the excretion of potentially toxic metabolites of tryptophan-rich proteins. The results demonstrate first that the serosa represents an important target for ovicide pesticides and second that it plays a vital role as an excretory organ during embryogenesis.

Coincident fragment detection in strong field photoionization and dissociation of H2

Electron-ion momentum spectroscopy is used to investigate the correlated electronic and nuclear motion in fragmentation of H2 in 4 x 10(14) W/cm(2), 25 fs laser pulses at 795 nm. Reaction channel dependent photoelectron spectra indicate that besides the main, stepwise H2 ionization H2(+) dissociation mechanism resulting in the products H(1s) + H(+) + e(-) a second new mechanism has to be assumed. The momentum distribution of H(+) ions in the dissociation channels H(1s) + H(+) + e(-) and 2H(+) + 2e(-) is found to be independent of the kinetic energy of the photoelectrons.

Testis differentiation in the glowworm, Lampyris noctiluca, with special reference to the apical tissue

The gonads of Lampyris noctiluca are sexually undifferentiated during the first larval instars. They consist of many gonadal follicles that include the germ stem cells enclosed by the somatic cells of the follicle wall. Follicle wall cells are more numerous at the follicle apices than at the distal parts, but different cell types cannot be distinguished. In male larvae, the appearance of apical follicle tissue, derived from follicle wall cells, marks the onset of testis differentiation. When maximally expressed, the apical tissue occupies about the upper half of the testis follicles and can be observed in larvae of the fifth and sixth instar. The apical tissue is characterized by its "light" appearance (due to poor stainability) caused by the small number cellular organelles, especially a paucity of free ribosomes. Maximal expression of the apical tissue must be very brief, since in most examined fifth and sixth instar larvae the apical tissue is partly or mostly translocated into the center of the upper half of the follicles and spermatogonia then occupy the apical follicle tips. During and after translocation apical cells form projections that grow around clusters of spermatogonia (spermatocysts). Thus, the apical cells transform into spermatocyst envelope cells. They retain their "light" appearance but undergo dramatic subcellular differentiation: smooth ER becomes extremely prominent, forming stacks and whorls of parallel cisternae. Golgi complexes are also conspicuous. The cellular organization suggests secretory activity. The possibility of ecdysteroid production and its function is discussed. The spermatocyst envelope cells persist into the pupal stage. When spermiohistogenesis takes place in cysts, cyst envelope cells show signs of regression. At all stages of testis development apical cells and their derivatives, the spermatocyst envelope cells, phagocytize degenerating spermatogonia. Although this is an important task of these cells, the impressive formation of sER in the cyst envelope cells is indicative of an additional, as yet unknown, function.

The serosa of Manduca sexta (Insecta, Lepidoptera): ontogeny, secretory activity, structural changes, and functional considerations

In Manduca sexta, the blastoderm forms successively and becomes immediately cellularized as the cleavage energids reach the surface of the oocyte. Presumptive serosal cells are large and contain 2 or 4 large polyploid nuclei; presumptive embryonic cells are small and mononuclear. All parts of the blastoderm participate in the uptake and digestion of yolk material. About 10 h post-oviposition, the blastoderm breaks at the amnioserosal fold and the extraembryonic part closes above the germ band and constitutes the serosa (12 h post-oviposition, i.e. 10% development completed). At once, the serosa starts to secrete a cuticle consisting of an epi- and a lamellated endocuticle. Detachment of the serosal cuticle, 22h post-oviposition, is reminiscent of apolysis of larval cuticle. Thereafter, the serosa deposits a membranous structure, the serosal membrane. The sercretory process lasts from 23h to 44h post-oviposition. At first a fine granular layer, then an amorphous, spongy-like, fibrillar layer is secreted via microvilli. This persisting membrane is tough, rubbery and very elastic. It may serve to bolster the serosa during katatrepsis (48h post-oviposition) and later embryonic movements. After detachment of the serosal membrane, 44h post-oviposition, a distinct subcellular reorganization of the serosa takes place. The nuclei become still larger and more irregular. Uptake of yolk granules, but not of lipid droplets, ceases, although interaction of serosa and yolk cells are intense. Serosal cells include many mitochondria, large areas of rER, besides some sER, increasing amounts of lysosomal bodies and prominent Golgi complexes. Most conspicuous is the assembly of spindle-shaped, electron-lucent vesicles below the apical surface. These vesicles may contain metabolic products which are released into the peripheral space. The studies show that the serosa assumes changing functions during embryogenesis: digestion of yolk substances, synthesis of a serosal cuticle and a serosal membrane, which may have a protective function, and excretion.

Tris-benzimidazole derivatives: design, synthesis and DNA sequence recognition

Two tris-benzimidazole derivatives have been designed and synthesized based on the known structures of the bis-benzimidazole stain Hoechst 33258 complexed to short oligonucleotide duplexes derived from single crystal X-ray studies and from NMR. In both derivatives the phenol group has been replaced by a methoxy-phenyl substituent. Whereas one tris-benzimidazole carries a N-methyl-piperazine at the 6-position, the other one has this group replaced by a 2-amino-pyrrolidine ring. This latter substituent results in stronger DNA binding. The optimized synthesis of the drugs is described. The two tris-benzimidazoles exhibit high AT-base pair (bp) selectivity evident in footprinting experiments which show that five to six base pairs are protected by the tris-benzimidazoles as compared to four to five protected by the bis-benzimidazoles. The tris-benzimidazoles bind well to sequences like 5'-TAAAC, 5'-TTTAC and 5'-TTTAT, but it is also evident that they can bind weakly to sequences such as 5'-TATGTT-3' where the continuity of an AT stretch is interrupted by a single G*C base pair.

Differential infectivity of two Pseudomonas species and the immune response in the milkweed bug, Oncopeltus fasciatus (Insecta: Hemiptera)

Pseudomonas aeruginosa and Pseudomonas putida show a profound differential infectivity after inoculation in Oncopeltus fasciatus. Whereas P. putida has no significant impact on nymphs, P. aeruginosa kills all experimental animals within 48 h. Both Pseudomonas species, however, induce the same four hemolymph peptides in O. fasciatus. Also injection of saline solution and injury induced these peptides. In general peptide induction was stronger in nymphs than in adult males. A significantly higher number of nymphs survived a challenge with P. aeruginosa when an immunization with P. putida preceded. The antibacterial properties of the hemolymph were demonstrated in inhibition experiments with P. putida. Two of the four inducible peptides (peptides 1 and 4) could be partially sequenced after Edman degradation and were compared with known antibacterial peptides. Peptide 1, of 15 kDa, showed 47.1% identity with the glycine-rich hemiptericin of Pyrrhocoris apterus. Peptide 4, of 2 kDa, had a 77.8% identity with the proline-rich pyrrhocoricin of P. apterus and a 76.9% identity with metalnikowin 1 of Palomena prasina. Peptides 2 and 3 are also small, with molecular weights of 8 and 5 kDa.

Separation of recollision mechanisms in nonsequential strong field double ionization of Ar: the role of excitation tunneling

Vector momentum distributions of two electrons created in double ionization of Ar by 25 fs, 0.25 PW/cm(2) laser pulses at 795 nm have been measured using a "reaction microscope." At this intensity, where nonsequential ionization dominates, distinct correlation patterns are observed in the two-electron momentum distributions. A kinematical analysis of these spectra within the classical "recollision model" revealed an (e,2e)-like process and excitation with subsequent tunneling of the second electron as two different ionization mechanisms. This allows a qualitative separation of the two mechanisms demonstrating that excitation-tunneling is the dominant contribution to the total double ionization yield.

Short report: floxacrine analog WR 243251 inhibits hematin polymerization

Floxacrine was a promising antimalarial compound that led to the identification of WR 243251. On the basis of their structures, we suspected that these compounds might be good inhibitors of hematin polymerization. Indeed, WR 243251 was as potent and floxacrine was only 2-fold less potent than chloroquine as inhibitors of this process. However, this hematin polymerization inhibition did not completely account for the increased antimalarial potency of WR 243251 versus chloroquine. The WR 243251 ketone hydrolysis product WR 243246 was without activity against hematin polymerization. These data also confirm that hematin polymerization inhibition can be quite sensitive to small changes in inhibitor structure.

Double ionization of helium by electron-impact: complete pictures of the four-body breakup dynamics

The dynamics of He double ionization by 2 keV electron impact is studied experimentally for a momentum transfer of 0.6 a.u. at excess energies of 10 and 40 eV. Complete sets of fivefold differential cross sections are presented for all electron emission angles in coplanar geometry. Contributions beyond the first Born approximation are identified comparing experimental data with first order convergent close-coupling calculations which are in considerably better agreement with the present experiment than with the earlier measurement of Kheifets et al. [J. Phys. B 32, 5047 (1999)].

Non-sequential double ionization of Ne in intense laser pulses: a coincidence experiment

The dynamics of Neon double ionization by 25 fs, 1.0 PW/cm 2 laser pulses at 795 nm has been studied in a many particle coincidence experiment. The momentum vectors of all ejected atomic fragments (electrons and ions) have been measured using combined electron and recoil-ion momentum spectroscopy. Electron emission spectra for double and single ionization will be discussed. In both processes the mean electron energies differ considerably and high energetic electrons with energies of more than 120 eV have been observed for double ionization. The experimental results are in qualitative agreement with the rescattering model.

Ergastoplasmic paracrystalline inclusion bodies in the adipose gonadal envelope and fat body of the glow worm, Lampyris noctiluca (Insecta, Coleoptera)

The gonads of glow worm larvae are enveloped by adipose tissue which represents a specialized fat body. The adipose gonadal envelope, and also to a lesser extent the fat body cells, contain tubular paracrystalline inclusion bodies (PIBs). Cells of other tissues are devoid of such inclusions. The PIBs form in the cisternae of rough ER. In young larvae PIB formation is sparse, but at advanced larval stages PIBs often occur as bundles in stacks of ergastoplasm. Typically, a PIB within a cisterna consists of four to seven parallel tubules. The outer diameter of a tubule is ca 28.8 nm and the width of the tubule lumen ca 12.2 nm. The "wall" of a tubule contains globular protein subunits of ca 8.3 nm diameter; the subunits are arranged helically. Since the adipose gonadal envelope progresses through a cytological differentiation process during differentiation and maturation of the gonads, the increased number of PIBs may indicate enhanced metabolic activity of the tissue related to nutrition of the growing gonads.

20-Hydroxyecdysone-induced differentiation and apoptosis in the Drosophila cell line, l(2)mbn

20-Hydroxyecdysone has an inhibitory effect on the proliferation of l(2)mbn cells, causes vacuolization and fragmentation of cells, and promotes a strong phagocytotic activity. From several lines of evidence, it can be concluded that 20-hydroxyecdysone induces apoptosis. Long-term video observations following the fate of individual cells, scanning and transmission electron microscopy reveal the typical characteristics of apoptosis: sequestration of small cellular protuberances or larger parts of the cell with nuclear fragments (apoptotic bodies), chromatin condensation, condensation and vesiculation of cytoplasm, whereas the mitochondria retain their normal appearance. The induction of apoptosis by 20-hydroxyecdysone was confirmed by the TUNEL reaction and quantitatively determined by a method based on this reaction. Onset of apoptosis precedes phagocytotic activity. JH III alone has no clear-cut effect on l(2)mbn cells. In double treatments, the inhibitory effect of 20-hydroxyecdysone on cell proliferation is significantly reduced by the addition of JH III. Whether or not JH III also reduces apoptotic activity is not yet clear. It is shown that the l(2)mbn cell line is an advantageous model system for the exploration of steroid-induced apoptosis.

Hematin polymerization assay as a high-throughput screen for identification of new antimalarial pharmacophores

Hematin polymerization is a parasite-specific process that enables the detoxification of heme following its release in the lysosomal digestive vacuole during hemoglobin degradation, and represents both an essential and a unique pharmacological drug target. We have developed a high-throughput in vitro microassay of hematin polymerization based on the detection of (14)C-labeled hematin incorporated into polymeric hemozoin (malaria pigment). The assay uses 96-well filtration microplates and requires 12 h and a Wallac 1450 MicroBeta liquid scintillation counter. The robustness of the assay allowed the rapid screening and evaluation of more than 100, 000 compounds. Random screening was complemented by the development of a pharmacophore hypothesis using the "Catalyst" program and a large amount of data available on the inhibitory activity of a large library of 4-aminoquinolines. Using these methods, we identified "hit" compounds belonging to several chemical structural classes that had potential antimalarial activity. Follow-up evaluation of the antimalarial activity of these compounds in culture and in the Plasmodium berghei murine model further identified compounds with actual antimalarial activity. Of particular interest was a triarylcarbinol (Ro 06-9075) and a related benzophenone (Ro 22-8014) that showed oral activity in the murine model. These compounds are chemically accessible and could form the basis of a new antimalarial medicinal chemistry program.

Characterization of chloroquine-hematin mu-oxo dimer binding by isothermal titration calorimetry

Numerous studies indicate that a key feature of chloroquine's (CQ) antimalarial activity is its interaction with hematin. We now characterize this CQ-hematin interaction in detail using isothermal titration calorimetry (ITC). Between pH 5.6 and 9.0, association constants (K(a) values) for enthalpy-driven CQ-hematin mu-oxo dimer binding fell in the narrow range of 2.3-4.4 x 10(5) M(-1). It is therefore probable that CQ-hematin mu-oxo dimer binding affinity does not diminish at the pH range (4.8-5.4) of the parasite food vacuole. The binding affinity was unaffected by high salt concentrations, suggesting that ionic interactions do not contribute significantly to this complexation. With increasing ionic strength, the entropic penalty of CQ-hematin mu-oxo dimer binding decreased accompanied by increased hematin mu-oxo dimer aggregation. A stoichiometry (n) of 1:4 in the pH range 6.5-9.0 indicates that CQ binds to two hematin mu-oxo dimers. At pH 5.6, a stoichiometry of 1:8 suggests that CQ binds to an aggregate of four hematin mu-oxo dimers. This work adds further evidence supporting the hypothesis that CQ impedes hematin monomer incorporation into hemozoin by producing a forward shift in the hematin monomer-hematin mu-oxo dimer equilibrium, contributing to a destructive accumulation of soluble forms of hematin in the parasite and leading to its death by hematin poisoning.

Momentum distributions of ne(n+) ions created by an intense ultrashort laser pulse

Vector momentum distributions of Ne(n+) (n = 1,2,3) ions created by 30 fs, approximately 1 PW/cm(2) laser pulses at 795 nm have been measured using recoil-ion momentum spectroscopy. Distinct maxima along the light polarization axis are observed at 4.0 and 7.5 a.u. for Ne2+ and Ne3+ production, respectively. Hence, mechanisms based on an instantaneous release of two (or more) electrons can be ruled out as a dominant contribution to nonsequential strong-field multiple ionization. The positions of the maxima are in accord with kinematical constraints set by the classical "rescattering model."

Expression of phase-specific haemolymph polypeptides in a laboratory strain and field catches of Schistocerca gregaria

Uvarov's theory of locust phase polymorphism implies a differential phase-specific gene expression. It was the goal of the present investigation to provide data on the molecular level for this concept. We used the technique of 2D gel electrophoresis to generate haemolymph polypeptide maps from mature locust males. Under the given conditions we identified 238 polypeptide spots by their molecular weight and isoelectrical point. Isolated and crowded males from the Mainz strain, all originating from crowded ancesters, differed in 20 spots: three were solitary-specific and 17 crowded-specific. Field catches of solitary and gregarious S. gregaria in Mauritania revealed that those males showed the phase-specific expression of the same 20 polypeptide spots as the Mainz strain. (It should be mentioned that the field catches and the Mainz animals differed in nine spots, but none of them was phase-specific.) As a crosscheck we reared originally solitary field catches for two generations under crowded conditions. This resulted in the repression of one solitary-specific spot and the expression of 14 gregarious/crowded-specific spots. Since JH conceivably plays a decisive role in the manifestation of the solitary phase we applied the JH analogue fenoxycarb to crowded Mainz males. 15 days after the treatment nine of the 17 gregarious-specific polypeptide spots were repressed. The fact that experimental manipulations-limited by time-cannot alter the expression of all phase-specific polypeptides may reflect the observation that, in nature, some phase characteristics can change within hours whereas others need several generations. The results provide evidence that a number of haemolymph polypeptides are expressed and repressed, respectively, in relation to phase.

Structural specificity of chloroquine-hematin binding related to inhibition of hematin polymerization and parasite growth

Considerable data now support the hypothesis that chloroquine (CQ)-hematin binding in the parasite food vacuole leads to inhibition of hematin polymerization and parasite death by hematin poisoning. To better understand the structural specificity of CQ-hematin binding, 13 CQ analogues were chosen and their hematin binding affinity, inhibition of hematin polymerization, and inhibition of parasite growth were measured. As determined by isothermal titration calorimetry (ITC), the stoichiometry data and exothermic binding enthalpies indicated that, like CQ, these analogues bind to two or more hematin mu-oxo dimers in a cofacial pi-pi sandwich-type complex. Association constants (K(a)'s) ranged from 0.46 to 2.9 x 10(5) M(-1) compared to 4.0 x 10(5) M(-1) for CQ. Remarkably, we were not able to measure any significant interaction between hematin mu-oxo dimer and 11, the 6-chloro analogue of CQ. This result indicates that the 7-chloro substituent in CQ is a critical structural determinant in its binding affinity to hematin mu-oxo dimer. Molecular modeling experiments reinforce the view that the enthalpically favorable pi-pi interaction observed in the CQ-hematin mu-oxo dimer complex derives from a favorable alignment of the out-of-plane pi-electron density in CQ and hematin mu-oxo dimer at the points of intermolecular contact. For 4-aminoquinolines related to CQ, our data suggest that electron-withdrawing functional groups at the 7-position of the quinoline ring are required for activity against both hematin polymerization and parasite growth and that chlorine substitution at position 7 is optimal. Our results also confirm that the CQ diaminoalkyl side chain, especially the aliphatic tertiary nitrogen atom, is an important structural determinant in CQ drug resistance. For CQ analogues 1-13, the lack of correlation between K(a) and hematin polymerization IC(50) values suggests that other properties of the CQ-hematin mu-oxo dimer complex, rather than its association constant alone, play a role in the inhibition of hematin polymerization. However, there was a modest correlation between inhibition of hematin polymerization and inhibition of parasite growth when hematin polymerization IC(50) values were normalized for hematin mu-oxo dimer binding affinities, adding further evidence that antimalarial 4-aminoquinolines act by this mechanism.