Measurement of the fluorescence lifetime of GFP in high refractive index levitated droplets using FLIM

Green fluorescent protein (GFP) is a widely used fluorescent probe in the life sciences and biosciences due to its high quantum yield and extinction coefficient, and its ability to bind to biological systems of interest. This study measures the fluorescence lifetime of GFP in sucrose/water solutions of known molarity in order to determine the refractive index dependent lifetime of GFP. A range of refractive indices from 1.43-1.53 were probed by levitating micron sized droplets composed of water/sucrose/GFP in an optical trap under well-constrained conditions of relative humidity. This setup allows for the first reported measurements of the fluorescence lifetime of GFP at refractive indices greater than 1.46. The results obtained at refractive indices less than 1.46 show good agreement with previous studies. Further experiments that trapped droplets of deionised water containing GFP allowed the hygroscopic properties of GFP to be measured. GFP is found to be mildly hygroscopic by mass, but the high ratio of molecular masses of GFP to water (ca. 1500 : 1) signifies that water uptake is large on a per-mole basis. Hygroscopic properties are verified using brightfield microscope imaging, of GFP droplets at low and high relative humidity, by measuring the humidity dependent droplet size. In addition, this experiment allowed the refractive index of pure GFP to be estimated for the first time (1.72 ± 0.07). This work provides reference data for future experiments involving GFP, especially for those conducted in high refractive index media. The work also demonstrates that GFP can be used as a probe for aerosol studies, which require determination of the refractive index of the aerosol of any shape.

Measurement of the Raman spectra and hygroscopicity of four pharmaceutical aerosols as they travel from pressurised metered dose inhalers (pMDI) to a model lung

Particle inhalation is an effective and rapid delivery method for a variety of pharmaceuticals, particularly bronchodilation drugs used for treating asthma and COPD. Conditions of relative humidity and temperature inside the lungs are generally very different from the outside ambient air, with the lung typically being warmer and more humid. Changes in humidity, from inhaler to lung, can cause hygroscopic phase transitions and particle growth. Increasing particle size and mass can negatively affect particle deposition within the lung leading to inefficient treatment, while deliquescence prior to impaction is liable to accelerate drug uptake. To better understand the hygroscopic properties of four pharmaceutical aerosol particles; pharmaceutical particles from four commercially available pressurised metered dose inhalers (pMDIs) were stably captured in an optical trap, and their composition was examined online via Raman spectroscopy. Micron-sized particles of salbutamol sulfate, salmeterol xinafoate, fluticasone propionate and ciclesonide were levitated and examined over a range of relative humidity values inside a chamber designed to mimic conditions within the respiratory tract. The effect of temperature upon hygroscopicity was also investigated for salbutamol sulfate particles. Salbutamol sulfate was found to have significant hygroscopicity, salmeterol xinafoate showed some hygroscopic interactions, whilst fluticasone propionate and ciclesonide revealed no observable hygroscopicity. Thermodynamic and structural modelling is used to explain the observed experimental results.

In Vivo Quantification of Peroxisome Tethering to Chloroplasts in Tobacco Epidermal Cells Using Optical Tweezers

Peroxisomes are highly motile organelles that display a range of motions within a short time frame. In static snapshots, they can be juxtaposed to chloroplasts, which has led to the hypothesis that they are physically interacting. Here, using optical tweezers, we tested the dynamic physical interaction in vivo. Using near-infrared optical tweezers combined with TIRF microscopy, we were able to trap peroxisomes and approximate the forces involved in chloroplast association in vivo in tobacco (Nicotiana tabacum) and observed weaker tethering to additional unknown structures within the cell. We show that chloroplasts and peroxisomes are physically tethered through peroxules, a poorly described structure in plant cells. We suggest that peroxules have a novel role in maintaining peroxisome-organelle interactions in the dynamic environment. This could be important for fatty acid mobilization and photorespiration through the interaction with oil bodies and chloroplasts, highlighting a fundamentally important role for organelle interactions for essential biochemistry and physiological processes.

3D prostate histology reconstruction: an evaluation of image-based and fiducial-based algorithms

PURPOSE

Evaluation of in vivo prostate imaging modalities for determining the spatial distribution and aggressiveness of prostate cancer ideally requires accurate registration of images to an accepted reference standard, such as histopathological examination of radical prostatectomy specimens. Three-dimensional (3D) reconstruction of prostate histology facilitates these registration-based evaluations by reintroducing 3D spatial information lost during histology processing. Because the reconstruction accuracy may constrain the clinical questions that can be answered with these data, it is important to assess the tradeoffs between minimally disruptive methods based on intrinsic image information and potentially more robust methods based on extrinsic fiducial markers.

METHODS

Ex vivo magnetic resonance (MR) images and digitized whole-mount histology images from 12 radical prostatectomy specimens were used to evaluate four 3D histology reconstruction algorithms. 3D reconstructions were computed by registering each histology image to the corresponding ex vivo MR image using one of two similarity metrics (mutual information or fiducial registration error) and one of two search domains (affine transformations or a constrained subset thereof). The algorithms were evaluated for accuracy using the mean target registration error (TRE) computed from homologous intrinsic point landmarks (3-16 per histology section; 232 total) identified on histology and MR images, and for the sensitivity of TRE to rotational, translational, and scaling initialization errors.

RESULTS

The algorithms using fiducial registration error and mutual information had mean ± standard deviation TREs of 0.7 ± 0.4 and 1.2 ± 0.7 mm, respectively, and one algorithm using fiducial registration error and affine transforms had negligible sensitivities to initialization errors. The postoptimization values of the mutual information-based metric showed evidence of errors due to both the optimizer and the similarity metric, and variation of parameters of the mutual information-based metric did not improve its performance.

CONCLUSIONS

The extrinsic fiducial-based algorithm had lower mean TRE and lower sensitivity to initialization than the intrinsic intensity-based algorithm using mutual information. A model relating statistical power to registration error for certain imaging validation study designs estimated that a reconstruction algorithm with a mean TRE of 0.7 mm would require 27% fewer subjects than the method used to initialize the algorithms (mean TRE 1.3 ± 0.7 mm), suggesting the choice of reconstruction technique can have a substantial impact on the design of imaging validation studies, and on their overall cost.

Dynamic position and force measurement for multiple optically trapped particles using a high-speed active pixel sensor

A high frame rate active pixel sensor designed to track the position of up to six optically trapped objects simultaneously within the field of view of a microscope is described. The sensor comprises 520 x 520 pixels from which a flexible arrangement of six independent regions of interest is accessed at a rate of up to 20 kHz, providing the capability to measure motion in multiple micron scale objects to nanometer accuracy. The combined control of both the sensor and optical traps is performed using unique, dedicated electronics (a field programmable gate array). The ability of the sensor to measure the dynamic position and the forces between six optically trapped spheres, down to femtonewton level, is demonstrated paving the way for application in the physical and life sciences.

Broadband Mie scattering from optically levitated aerosol droplets using a white LED

We describe a simple and efficient means of using a white LED source to illuminate an optically levitated aerosol droplet to enable study of broadband Mie scattering. The backscattered resonances are imaged through a spectrograph and CCD which show high resolution Mie scattering intensity distributions across a spectral range of 480 to 700 nm. The wide spectral range allows assignment of resonance mode numbers and mode orders using conventional Mie theory calculations. Accurate droplet sizing, within +/- 2 nm, is possible for water-based droplets with radii between 2 microm and 8 microm. We additionally demonstrate that the refractive index dispersion can be determined from a single refractive index value at known wavelength. Finally, morphological droplet dynamics are presented showing non-linear droplet evaporation behaviour at a temporal resolution of 100 milliseconds.

Immobilisation and synthesis of DNA on Si(111), nanocrystalline porous silicon and silicon nanoparticles

Oligonucleotides have been synthesized on hydrogen-terminated Si(111) and porous silicon using surface hydrosilation of difunctional molecules (1,(omega)-dimethoxytritylundecenol) to produce a monolayer bearing suitable reactive groups to allow automated solid-phase DNA synthesis. The absence of an intervening oxide enables electrochemical characterisation of the surface-bound oligonucleotides. Complementary sequences to the DNA synthesized on Si(111) undergo hybridisation at the surface and a straightforward electrochemical quantitation of the amount of synthesized DNA and its hybridisation efficiency (47%) is possible using Ru(NH3)6(3+) as a redox label. In the case of DNA synthesized in porous silicon, electron transfer (ET) between DNA and the underlying bulk semiconductor can be studied by cyclic voltammetry, however the anisotropic diffusion inside the porous layer and the large resistance of the porous silicon results in voltammograms for which thin-layer behaviour is not observed and the peak currents increase with the square root of scan rate. We interpret these voltammograms in terms of charge transport limitations in the layer of metal centres bound to the DNA inside the pores. Further evidence for this interpretation has been obtained using scanning electrochemical microscopy (SECM) to study the charge transport between redox species in films of DNA synthesized on Si(111) surfaces that are in contact with an aqueous phase. As the bulk concentration of Ru(NH3)6(3+) is reduced below about 250 microM the SECM feedback indicates that the rate of charge transport between surface-bound Ru(NH3)6(3+) exceeds that due to diffusion in the liquid phase. Electrochemical quantitation of the DNA is not possible in this situation, however we have been able to obtain independent determinations using radioassay based on 32P or UV/VIS spectrophotometry of dimethoxytrityl cation cleaved from the porous layer. In the case of the former, use of labelled complementary sequences shows an inverse relationship between the current density used to prepare the porous silicon and the amount of hybridisation. This can be interpreted in terms of the specific surface area of the porous silicon layers since the hybridisation efficiencies (ca. 40%) obtained by comparing DMT+ cleaved from sequences synthesized on the surface and then from complementary sequences after hybridisation were relatively insensitive to the current density used to prepare the layers. Our recent work has also been concerned with individual Si nanocrystals generated by breaking up porous silicon during thermal hydrosilation reactions. FTIR spectroscopy shows these particles are also coated with an organic Si-C-bonded monolayer and they form stable, non-turbid and strongly luminescent (lambdamax = 600-650 nm) dispersions in apolar solvents (L. H. Lie, M. S. Duerdin, E. M. Tuite, A. Houlton and B. R. Horrocks, J. Electroanal. Chem., 2002, 538/539, 183). The effect of carrying out synthetic reactions on the porous silicon prior to breaking up the layer is to produce instead larger, micron-scale assemblies with a nanometre scale internal structure. Micron-sized particles of porous silicon produced by breaking up the layer can be probed by confocal Raman spectroscopy using the electric field of a focused laser to trap such particles. Although these particles are also luminescent, the use of relatively long wavelength laser excitation (lambda = 785 nm) allows acquisition of Raman spectra from individual particles in the optical trap. The bulk optical phonon mode at ca. 520 cm(-1) characteristic of crystalline silicon is red-shifted and broadened providing evidence for an internal nanometre scale substructure in these micron-sized particles and we also see evidence for this mode in the colloidal suspensions of the Si nanoparticles. We propose a model for the formation of these two types of particles and briefly discuss the prospects to extend our solid-phase synthesis on porous silicon to allow the facile synthesis of luminescent Si nanocrystals bearing DNA or other biomolecules.

Measurement of long-range repulsive forces between charged particles at an oil-water interface

Using a laser tweezers method, we have determined the long-range repulsive force as a function of separation between two charged, spherical polystyrene particles (2.7 microm diameter) present at a nonpolar oil-water interface. At large separations (6 to 12 microm between particle centers) the force is found to decay with distance to the power -4 and is insensitive to the ionic strength of the aqueous phase. The results are consistent with a model in which the repulsion arises primarily from the presence of a very small residual electric charge at the particle-oil interface. This charge corresponds to a fractional dissociation of the total ionizable (sulfate) groups present at the particle-oil surface of approximately 3 x 10(-4).

Synthesis of 4-methyl-5-arylpyrimidines and 4-arylpyrimidines: route specific markers for the Leuckardt preparation of amphetamine, 4-methoxyamphetamine, and 4-methylthioamphetamine

General synthetic routes to 4-methyl-5-arylpyrimidines and 5-arylpyrimidines are described. 4-Benzylpyrimidine, 4-methyl-5-phenylpyrimidine, 4-(4-methoxybenzyl)pyrimidine, and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been positively identified as route-specific by-products in the Leuckardt preparations of amphetamine and 4-methoxyamphetamine. Using headspace solid phase microextraction (SPME) 4-(4-methoxybenzyl)pyrimidine and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been identified in illicit tablets containing 4-methoxyamphetamine. This is an indication that illicit laboratories use the Leuckardt method for the preparation of 4-methoxyamphetamine. Flatliner tablets containing 4-methylthioamphetamine have been screened for the presence of 4-(4-methylthiobenzyl)pyrimidine and 4-methyl-5-(4-methylthiophenyl)pyrimidine using both headspace and aqueous phase SPME. As these pyrimidines were not detected it would appear likely that illicit laboratories are not using the Leuckardt method for the preparation of 4-methylthioamphetamine.

The synthesis and fluorescent properties of analogues of the zinc(II) specific fluorophore zinquin ester

The synthesis and fluorescent properties in the absence and presence of zinc(II) of a range of 2-substituted derivatives of N-(6-methoxy-2-methyl-8-quinolyl)-4-methylbenzenesulfonamide are described. These analogues formed complexes with zinc(II) as indicated by a bathochromic shift in their UV/vis spectra. Analogues with isobutenyl and isobutyl side chains at the 2-position formed fluorescent complexes whose fluorescence was stronger than that of the 2-methyl-containing parent. These derivatives were converted, via conversion to the phenol with boron tribromide and reaction with ethyl bromoacetate, to systems with ester-containing side chains analogous to zinquin ester, a specific cellular fluorophore for zinc(II). All of these ester derivatives formed complexes with zinc(II) resulting in a bathochomic shift in their UV/vis spectra. Compounds with isobutyl, isobutenyl, and styryl side chains exhibited increased fluorescence compared to that of zinquin ester in the presence of zinc(II). The compound with the 2-isobutyl side chain was more selective in its fluorescence for zinc(II) over cadmium(II) compared to zinquin ester.

The Structure of a Human Metabolite of Pholcodine

The structure of a metabolite of pholcodine produced by humans is shown, by spectroscopic and synthetic data, to be a morpholin-3-one (amide) derivative rather than the alternative morpholin-2-one ( lactone ) isomer. Acylation of diethanolamine leads to an N,O- diacyl product even when only 1 equiv. of acylating agent is used. A mechanism is proposed to account for this observation. The appropriately substituted diacyl product can be cyclized to give a morpholin-3-one derivative which can be coupled to morphine by using caesium carbonate to give the metabolite. Suitable morpholin-2-one systems were coupled with morphine in basic conditions to give the alternative metabolite structure whose lactone group hydrolysed on standing to form a hydroxy acid derivative.

The Synthesis of Zinquin Ester and Zinquin Acid, Zinc(II)-Specific Fluorescing Agents for Use in the Study of Biological Zinc(II)

The syntheses of Zinquin ester [ethyl [2-methyl-8-(p- tolylsulfonylamino )-6-quinolyloxy]acetate] and the corresponding acid, both of which are zinc(II)-specific fluorophores , are described. 6-Methoxy-2-methyl-8-(p- tolylsulfonylamino ) quinoline (2) can be demethylated , with boron tribromide, to form either the expected phenol or a mixture of the phenol and the corresponding 5-bromo derivative depending upon the reaction conditions. These compounds react with ethyl bromoacetate to give the corresponding esters, as well as the 5-ethoxycarbonyl derivative formed by electrophilic substitution. Halogenation of the sulfonamide (2) occurs readily at the 5-position. The 5-iodo product undergoes a Heck coupling with ethyl acrylate . The crystal structures of ethyl [5-ethoxycarbonylmethyl-2-methyl-8-(p- tolylsulfonylamino )-6-quinolyloxy]acetate and [5-carboxymethyl-2-methyl-8-(p- tolylsulfonylamino )-6-quinolyloxy]acetic acid are described.

Changes in distribution of labile zinc in mouse spermatozoa during maturation in the epididymis assessed by the fluorophore Zinquin

The Zn(II)-specific fluorophore Zinquin was used to determine the regional distribution of free or loosely-bound Zn(II) in mouse spermatozoa. Spermatozoa from the testes exhibited bright fluorescence over the entire head; those from the caput epididymides generally fluoresced more brightly in the post-acrosomal region; and spermatozoa from the caudae epididymides fluoresced less brightly, with foci of fluorescence over the sperm head which were lost after extraction with Triton X-100 and hence appeared to be membrane-associated. Treatment of cauda sperm with sodium dodecyl sulfate resulted in a bright uniform Zinquin fluorescence in the heads, similar to that observed in caput sperm, indicating that the two types of sperm have similar amounts of head Zn(II) but that the availability of Zn(II) for binding Zinquin is different. By contrast, the intensity of tail fluorescence was similar in spermatozoa from different regions of the male reproductive tract and was largely unaffected by Triton X-100 extraction, consistent with an intracellular location. Similar differences were observed between caput sperm and cauda sperm in the rat. It is concluded that visualization and measurement of free or loosely-bound Zn(II) in subcellular compartments of spermatozoa should facilitate investigation of the role of this metal in the development and function of spermatozoa and abnormalities that might accompany infertility and Zn(II) deficiency.

The Cyclization of Hex-5-Enylcarbamates and Related Compounds With Benzeneselenenyl Chloride and Some Reactions of the 2-Substituted Piperidine Products

The reaction of hex-5-enylcarbamates with benzeneselenenyl chloride gives adducts which cyclize , in the presence of silica or stannic chloride, to 2-phenylselenomethylpiperidine-1-carboxylates. The corresponding selenoxides eliminate to form 2-methylenepiperidine derivatives which are unstable, both thermally and on silica. The selenoxides also undergo a Pummerer-type reaction to form 2-acetoxy( phenylseleno ) methylpiperidine systems which can be oxidatively converted into a piperidine 2-aldehyde. The selenoxides react with carbon tetrachloride in base to form a 2,2,2-trichloroethyl substituent . Both the selenoxides and the phenylseleno groups of the cyclized products can be displaced by nucleophiles. Ethyl hept-6-enylcarbamate did not give a cyclic product with benzeneselenenyl chloride and silica, and gave a poor yield of a hexahydroazepine with stannic chloride. Hex-5-enamide cyclized to give a lactone, rather than a lactam , product. Hex-5-enenitrile gave Ritter reaction products with benzeneselenenyl chloride in acetonitrile , and a dimer in non- nucleophilic solvents.

Measurement of zinc in hepatocytes by using a fluorescent probe, zinquin: relationship to metallothionein and intracellular zinc

Zinquin [ethyl (2-methyl-8-p-toluenesulphonamido-6-quinolyloxy)acetate], a new intracellular zinc fluorophore, was used to reveal and to measure Zn in cultured rat hepatocytes before and after metallothionein (MT) induction. Hepatocytes labelled with an intense extranuclear fluorescence. Culture with combinations of Zn, dexamethasone and interleukin-6, increased intracellular MT by 24-fold, Zn 3-fold, and Zinquin fluorescence by approx. 2-fold above control values. Zinquin fluorescence correlated in descending order with the total cellular Zn (r = 0.747), exchangeable Zn (r = 0.735), soluble cytosolic Zn (r = 0.669) and MT (r = 0.666). When Zinquin was incubated with a cytosolic fraction of liver proteins before Sephadex G-75 column chromatography, it fluoresced with free, MT-incorporated and protein-bound Zn. Although only a slight attenuation of fluorescence was seen with high-molecular-mass protein-bound Zn, MT was degraded by 60% in the presence of Zinquin. The undegraded Zn-MT fluoresced at about 20% of the expected intensity. Although Zinquin fluoresces with all cytosolic Zn, caution is required when comparisons are made between samples with different concentrations of MT. This limitation was demonstrated by staining liver slices from adjuvant-treated rats where MT was increased 24-fold, intracellular Zn by 77%, but Zinquin fluorescence by only 19% above controls. Nevertheless, Zinquin should prove to be a useful tool for studying the distribution of Zn in living cells.

Flux of intracellular labile zinc during apoptosis (gene-directed cell death) revealed by a specific chemical probe, Zinquin

BACKGROUND

The transition metal Zn(II) is thought to regulate cell and tissue growth by enhancing mitosis (cell proliferation) and suppressing the counterbalancing process of apoptosis (gene-directed cell death). To investigate the role of Zn(II) further, we have used a UV-excitable Zn(II)-specific fluorophore, Zinquin. The ester group of Zinquin is hydrolyzed by living cells, ensuring its intracellular retention; this allows the visualization and measurement of free or loosely-bound (labile) intracellular Zn(II) by fluorescence video image analysis or fluorimetric spectroscopy.

RESULTS

Here we show that in cells undergoing early events of apoptosis, induced spontaneously or by diverse agents, there is a substantial increase in their Zinquin-detectable Zn(II). This increase occurred in the absence of exogenous Zn(II) and before changes in membrane permeability, consistent with a release of Zn(II) from intracellular stores or metalloproteins rather than enhanced uptake from the medium. We propose that there is a major redistribution of Zn(II) during the induction of apoptosis, which may influence or precipitate some of the later biochemical and morphological changes.

CONCLUSIONS

The phenomenon of Zn(II) mobilization, revealed by Zinquin, presents a new element in the process of apoptosis for investigation and may permit rapid and sensitive identification of apoptotic cells, particularly in those tissues where their frequency is low.

Video image analysis of labile zinc in viable pancreatic islet cells using a specific fluorescent probe for zinc

We used an intracellular zinc-specific fluorophore, Zinquin, in conjunction with fluorescence video image analysis, to reveal labile zinc in pancreatic islet cells, which concentrate this metal for use in synthesis, storage, and secretion of insulin. Zinquin vividly demonstrated zinc in the islet cell secretory granules, which formed a brightly labeled crescent in the cytoplasm between one side of the nucleus and the plasma membrane. Lower but still appreciable amounts of zinc were detected in the remaining cytoplasm, but there was little labeling in the nucleus. Fluorescence intensity varied among islet cells, suggesting differences in zinc content. Their average fluorescence intensity greatly surpassed that of the surrounding pancreatic acinar cells in frozen sections of pancreas and in all other types of cell studied, including lymphocytes, neutrophils, fibroblasts, and erythrocytes. Less labile zinc was detected in cells of the mouse insulinoma cell line NIT-1, regardless of whether they were maintained in long-term culture in the presence or absence of exogenous extracellular zinc. Exposure of islet or insulinoma cells to a high concentration of glucose or other secretagogue decreased the content of labile zinc. Zinquin should be a useful probe for revealing changes in zinc homeostasis in islet B-cells that may be important in their dysfunction and death during diabetes.

Attempted Heterocyclic Syntheses Through Electrophilic Ring Closure Reactions of 2-Allylaniline Systems Containing Larger Side Chains

The electrophile-initiated cyclization of some 2-allylanilines and their amide derivatives has been further investigated. Although 2-allylanilines with small, allylic substituents such as methyl reacted with iodine to yield 3-iodo-1,2,3,4-tetrahydroquinolines the 2-allylanilines with larger substituents related to those of virantmycin provided low yields of the tetrahydroquinoline as part of a complex product mixture.

Central Nervous System Active Compounds. XVII. Some Reactions of 6-Chloro-4,4-dimethyl-1,3,4,5-tetrahydro-2H-azepin-2-one and Its Dechlorinated Derivative

The vinyl chloride group of the title compound can be reduced to the enamide by using sodium metal. The enamide reacts with diborane or mercuric acetate to place a functional group at C7. The vinyl chloride is stable to hydrolysis under a variety of mild conditions but reacts with alkoxides under reflux to form a 6,7-dialkoxy derivative. A small amount of a dimer was obtained from the reaction of a mixture of unsaturated chlorocaprolactams with hydroxide.

Grignard Addition Reactions to 1,4-Difunctionalized But-2-ynes

Trisubstituted alkenes of E geometry have been prepared by anti addition of Grignard reagents to 1,4-difunctionalized but-2-ynes. Addition of primary, secondary and aromatic Grignard reagents to but-2-yne-1,4-diol provided (E)-2-substituted but-2-ene-1,4-diols as major products along with the corresponding 2-substituted buta-2,3-dien-1-ols. Addition of phenylmagnesium bromide to the mono- and di-methyl ethers of but-2-yne-1,4-diol gave 2,3-diphenyl-1,3-diene. Treatment of 4-dimethylaminobut-2-yn-1-ol with primary alkyl and alkenyl Grignard reagents afforded the 2-substituted anti addition product regiospecifically, stereospecifically and in high yield. Reaction of 1-dimethylamino-4-methoxybut-2-yne with butylmagnesium bromide provided only the 3-substituted anti addition product in good yield.

Configuration of triporphyrin ethers probed by fluorescence measurements

The fluorescence spectra and lifetimes of triporphyrin ethers derived from hematoporphyrin, mesoporphyrin and protoporphyrin were examined, together with relative hydrophobicities estimated from reverse-phase high performance liquid chromatography (HPLC) elution times. The following data suggest a molecular arrangement with two of the three rings in a "folded configuration". The trimers display a greater fluorescence yield (phi f) than the corresponding diporphyrin ethers which contain only the two folded rings. The fluorescence lifetime data for the trimers are consistent with signals from both a folded ring pair (7-8 ns) and a free ring (14 ns). Reverse-phase HPLC studies indicate that the trimers are intermediate in hydrophobicity between the monomers and dimers. Preliminary data suggest that, for certain peripheral substitutions, the trimer configuration is superior to the dimer for photodynamic therapy.

Photophysical and photobiological properties of diporphyrin ethers

Spectral properties of several diporphyrin ethers were assessed in different solvents and after accumulation by leukemia L1210 cells in vitro. To facilitate studies in a variety of solvents, both tetramethylesters of the diporphyrin ethers and free acids were employed. For comparison, studies on the corresponding porphyrin monomers were also carried out. The joining of two porphyrins by an ether linkage had several consequences. We observed a blue shift in the Soret band of the ethers, but not of the corresponding simple porphyrins, in protic solvents. This phenomenon is likely related to ether aggregation under conditions which promote H-bonding. The presence of an ether linkage was associated with enhanced fluorescence at 630-640 nm and decreased fluorescence lifetimes and yields, especially in protic solvents. The ether linkage was unaffected by intracellular enzymes, but porphyrin esters were readily hydrolyzed upon accumulation by L1210 cells. The joining of two hematoporphyrin molecules by an ether linkage promoted dye accumulation by L1210 cells. In contrast, accumulation of mesoporphyrin and protoporphyrin was thereby retarded.

Heterocyclic Syntheses Through Electrophilic Ring Closure Reactions of ortho-Allylaniline Systems

Amide derivatives of 2-allylanilines have been prepared by metallation of the amide derivatives of the corresponding 2-bromoanilines and subsequent reaction with an allylic halide. The electrophile -promoted cyclization of these compounds has been investigated. The free allylanilines readily undergo aminomercuration to form unstable mercury derivatives of tetrahydroquinolines but the corresponding amide derivatives do not cyclize. Instead, oxymercuration of the double bond occurs. The allylanilines react with iodine to yield 3-iodo-1,2,3,4-tetrahydroquinolines. The anion of 2,2,2-trifluoro-N-[4-hydroxymethyl-2-(3-methylbut-2-enyl)phenyl] acetamide reacts with iodine to give a 2,3-dihydroindole. These iodinated compounds can be further cyclized with base to form 7,7a-dihydro-1H-azirino[1,2-a] indoles. One of these aziridine systems was cleaved with hydrogen chloride to form a mixture of chlorinated tetrahydroquinoline and dihydroindole analogous to the iodo systems.

The Preparation of Analogs of the Ether-Linked Dimer and Oligomer Components of Hematoporphyrin Derivative

The preparation of ether-linked porphyrin dimers and oligomers which are analogues of those present in the anticancer drugs hematoporphyrin derivative and Photofrin IIR is described. These materials are prepared from the appropriately substituted porphyrins containing a 1-hydroxyethyl or a vinyl side chain through an intermediate 1-bromoethyl derivative. Ether-linked porphyrin dimers with ethyl, formyl , hydroxymethyl and 1-alkoxyethyl side chains were prepared, together with trimers and tetramers containing ethyl side chains. Some of the spectroscopic and biological properties of these compounds are discussed.

The composition of Photofrin II

The compositions of Photofrin II and haematoporphyrin derivative (HPD) were examined. Dihaematoporphyrin ester was unambiguously synthesized and shown by high performance liquid chromatography (HPLC) not to be a significant component of Photofrin II. Hydrolysis studies showed the presence of an acid-stable oligomer in Photofrin II which comprised about 40% of of an acid-stable oligomer in Photofrin II which comprised about 40% of the total sample. A dimer derivative was isolated from this oligomeric material by fully dehydrating the methyl-esterified acidic hydrolysis product of Photofrin II. The structure of this dimer, in which two porphyrin units are linked by a three-carbon bridge containing a double bond and a methyl group, was determined by nuclear magnetic resonance (NMR) and fast atom bombardment (FAB) mass spectrometry. An analogous trimer was also isolated and identified. Structures for the hydroxyl-containing precursors to the dimer and trimer, and for the acid-stable oligomeric material in Photofrin II, are suggested. The acid-stable oligomeric material is produced in the sodium hydroxide polymerization step of the preparation of Photofrin II.

Nitrate Selectivity of Ion-Exchange Resins and of Their Model Compounds. I. Conductance Measurements on Benzyltrialkylammonium Salts

The concentration dependence of the conductance in aqueous solution of a series of benzyltrialkylammonium chlorides, nitrates and sulfates was measured. The n-alkyl substituents in this series were methyl, ethyl, propyl , butyl and pentyl. The conductances of the chlorides, nitrates and sulfates fit satisfactorily the electrostatic ion pairing models relevant to 1 : 1 and 1 : 2 electrolytes. The extent of ion pairing is small in all the solutions studied but consistently larger for nitrates and sulfates compared with chlorides. The dependence of the association constants on the alkyl substitutents shows different trends for the monovalent anions compared with the sulfate salts.

The Synthesis of the Dimer and Trimer Ether-Linked Components of Hematoporphyrin Derivative

The preparation is described of all of the likely dimer and trimer ether-linked components of the anticancer material known as hematoporphyrin derivative. The hydroxyethyl side chain of one porphyrin, related to hematoporphyrin, reacts readily with a bromoethyl system derived from the same, or similar, hematoporphyrin -derived porphyrin to form a diporphyrin ether. The coupling reaction can be controlled to occur in situ, allowing the preparation of a symmetrical ether-linked dimer , or separately to provide an asymmetrically substituted porphyrin dimer . The bromoethyl groups can be formed from either the hydroxyethyl groups or, more slowly, from a vinyl side chain by using hydrogen bromide in dichloromethane. Ether-linked porphyrin trimers can be prepared by reacting a dibromoethyl system with 2 equiv. of a hydroxyethyl -containing porphyrin or by further reaction of an initially formed dimer. Hydroxyethyl side chains in the dimers and trimers are best obtained by reduction of an acetyl group. Some spectral properties of the products are described.

Reactions of Epoxides Derived From 2′-(3″-Methylbut-2″-enyl)trifluoroacetanilides

The intramolecular nucleophilic ring opening of the epoxides derived from 2′-(3″-methylbut-2″-enyl) trifluoroacetanilides has been investigated under both acidic and basic conditions. Boron trifluoride caused rearrangement of the epoxides to a ketone but no cyclization. Potassium carbonate in methanol caused regiospecific opening of the epoxides and generated dihydroindole products. The formation of a five-membered ring was confirmed by a single-crystal X-ray study of one of the products. The epoxides hydrolysed very readily in acidic conditions; the structure of one of the diol products was confirmed by a single-crystal X-ray study.

Treatment of advanced ovarian cancer with sequential combination chemotherapy

Fifty previously untreated patients with advanced or recurrent ovarian cancer (FIGO Stages III and IV) were treated with alternating combination chemotherapy. This consisted of high-dose doxorubicin (70 mg/m2) and cisplatin (100 mg/m2) alternated with CHF (cyclophosphamide, hexamethylmelamine, and 5-fluorouracil). Toxicity (myelosuppression, nephropathy, and neuropathy) was infrequent and mild. Clinical response rates were high (94% response, 62% complete clinical response), but the majority of patients had residual intraabdominal disease at second-look surgery (75%). Thirteen patients (26%) are alive after 4 years of observation (minimum follow-up). Survival was adversely influenced in patients who were older than 70, had Stage IV disease, residual tumor bulk greater than 2 cm, and who failed to achieve complete clinical remission. The median duration of survival (28 months) and percentage of long-term survivors appear similar to that in other platinum-based chemotherapy studies. Although the role of alternating combination chemotherapy in epithelial ovarian cancer remains undefined, it is likely that an alternate approach will be necessary to markedly improve survival rates for patients with this disease.

The photorespiratory hydrogen shuttle. Synthesis of phthalonic acid and its use in the characterization of the malate/aspartate shuttle in pea (Pisum sativum) leaf mitochondria

A method is presented for the preparation of pure phthalonic acid (PTA) in high yields. This PTA was used to determine the capacity of the malate/aspartate shuttle in pea (Pisum sativum) leaf mitochondria. The inhibition of glycine-dependent O2 uptake in the combined presence of 5 mM-aspartate and 5 mM-2-oxoglutarate (2-OG) was decreased by 55 +/- 22% (n = 13) in washed and 50 +/- 2% (n = 11) in purified mitochondria by 0.23 mM-PTA. This concentration of PTA had no effect on the oxidation of 5 mM-2-OG, suggesting that part of the observed inhibition of O2 uptake in the presence of aspartate and 2-OG was due to the production of oxaloacetate (OAA) by aspartate aminotransferase external to the mitochondrial inner membrane. Levels of external aspartate aminotransferase were estimated to be 24 +/- 1% (n = 4) and 13 +/- 1% (n = 4) of the total mitochondrial activity in washed and purified mitochondria respectively. Malate/aspartate-shuttle activity was estimated directly by measuring rates of malate efflux from isolated mitochondria and was found to match estimates of shuttle activity based on the PTA-insensitive inhibition of O2 uptake. Comparisons of malate/aspartate- and malate/OAA-shuttle activities indicated potentially similar rates of NADH export from pea leaf mitochondria under conditions in vivo. These extrapolated to whole-tissue rates of 5-11 mumol of NADH.h-1.mg of chlorophyll-1. The potential role of the malate/aspartate shuttle in the support of photorespiratory glycine oxidation in leaf tissue is discussed.

Direct measurement of salicylphenolic glucuronide in human urine

Indirect measurement of salicylphenolic glucuronide (SPG) has suggested that the formation of this metabolite from therapeutic doses of salicyclic acid (SA) is capacity-limited in humans. A direct high performance liquid chromatographic (HPLC) assay for SPG in human urine is described. SPG was prepared by a published method and purified by HPLC. On treatment with beta-glucuronidase, SPG yielded the expected amount of SA. Spectroscopic data, melting point, and optical rotation of the glucuronide and/or its triacetyl dimethyl ester derivative were consistent with the proposed structure. SPG was assayed using a 5-micron C18 column (temperature 55 degrees C) and fluorescence detection. A nonlinear gradient mobile phase at a flow rate of 2 ml/min was used, beginning with 100% 0.1 M pH 2.1 phosphate buffer and finishing with 84% buffer, 16% acetonitrile. Total run time was 25 min. Urine (10 microliter) was injected directly on the column, and quantitation was performed using urine standards. Within-run precision for SPG ranged from 1.2% at 150 mg/L to 2.4% at 5 mg/L. The limit of detection was less than 1 mg/L. A pilot study in two volunteers, each receiving a single 500-mg dose of sodium salicylate, was carried out to validate the usefulness of the assay.

Trimethyl(3-Oxido-1-Oxoinden-2-Yl)Ammonium, a New 1,4-Dipolar Ylide

Reaction of isobenzofuran-1(3H)-one ( phthalide ) and its derivatives with dimethylformamide dimethyl acetal in the presence of base gives small amounts (c. 10%)1 of the ylid trimethyl (3-oxido-1-oxoinden-2- yl )ammonium (3). The same compound is formed in higher yield from the corresponding 3-dimethylaminomethyleneisobenzofuran-1(3H)-one. Support for this structure comes from chemical degradation and its mode of synthesis, but relies mainly on X-ray crystallography. The title compound crystallizes as clear prisms in the monoclinic space group P21/n with a 15.992(2), b 9.329(4), c 7.112(3)Ǻ, β 90.15(3)° and Z 4. The structural final refinement of a full-matrix least-squares calculation converged with R 0.044 and Rw 0.045.

Central-Nervous-System Active Compounds .XVI. Some Chemistry of 6-Oxo Caprolactams Derived From an Enamine Ring-Expansion Synthesis

Several 6-oxo caprolactam derivatives have been prepared by the ring- expansion of enaminopyrrolidones with dimethyl acetylenedicarboxylate . Other acetylenic systems did not react. The products exist in the enol form of the β- keto ester system are are very resistant towards hydrolysis. They react with hydrazine and phenylhydrazine to form pyrazolo [3,4-c] azepinones in low yield. Many of the caprolactams and their pyrazolo -fused derivatives show central nervous system activity of a depressant nature in mice.

Central nervous system active compounds. XIV. On the cyclization of N-Acyl-N'-arylureas

The cyclization of N-acyl-N'-arylureas in polyphosphoric acid has been reinvestigated. The product is not only the 4-substituted quinazolin-2(1H)-one as reported, but also contains the 2-acylaniline in major proportions. Two minor products have also been isolated. At 80�, an intermediate has been detected, the properties of which are consistent with it being the corresponding 2-acylphenyl- urea. Acyl ureas with strongly electron-withdrawing acyl groups form major amounts of the corresponding anilide by the formal loss of cyanic acid. The application of this reaction to the synthesis of quinazolinylphthalides has been investigated.

The rearrangements of the nitrones of simple cyclic conjugated ketones

The ring expansions of N-methyl nitrones formed from cyclic conjugated ketones have been investigated.� Low yields of cyclic amides were obtained. In general, the best conditions for the rearrangementinvolved using p-toluenesulfonyl chloride and polyphosphoric acid in tetrahydrofuran. The parent ketone and, in some cases, an N-aryl sulfonamide were also obtained; mechanisms for their formation are discussed.

Central nervous system active compounds. XIII. The use of aminomethylene phthalides in the synthesis of phthalideisoquinoline alkaloids

Dimethylaminomethyleneisobenzofuranones react with alkoxyphenylethylamines in aqueous acidic solution to give phthalide isoquinolines (tetrahydroisoquinolinylisobenzofuranones) in moderate yields. N-Methylation gives the naturally occurring phthalideisoquinoline alkaloids. A number of examples of this reaction sequence are reported, including the synthesis of (�)-cordrastine, (�)-corlumine and (�)-adlumine.

Central nervous system active compounds. VIII. New syntheses of phthalide isoquinolines

Isoquinoline methiodides react with phthalides in the presence of sodium methoxide to give intermediates which may be reduced to phthalide isoquinolines with hydrogen or sodium cyanoborohydride. The predominant isomer formed is the erythro, which is also the more active compound when tested for central nervous system activity. The direct coupling of phthalides with dihydroisoquinoline methiodides under these conditions fails to occur.

Central nervous system active compounds. VI. Reissert compounds as precursors of 1-(3-phthalidy1)isoquinolines

The reactions of isoquinoline and phthalazine Reissert compounds with phthalaldehydic acids and their derivatives have been investigated as a means of synthesizing 1-(3-phthalidyl)isoquinolines. Of a variety of conditions tried those involving phase transfer were found, in general, to be the most suitable. The products, which are analogues of the convulsant alkaloid bicuculline, showed weak central nervous system depressant activity.