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Shelley N Jackson

Publications and source records attributed to Shelley N Jackson.

18 recordsLinked to original sources
PubMed2006

Direct MALDI-MS analysis of cardiolipin from rat organs sections.

Cardiolipins (CL) are mitochondria specific lipids. They play a critical role in ATP synthesis mediated by oxidative phosphorylation. Abnormal CL distribution is associated with several disease states. MALDI-MS and MALDI-MS/MS were used to demonstrate in situ analysis and characterization of CL from tissue sections of organs containing high concentrations of mitochondria. Once the experimental parameters were established, a survey of CL distribution in heart, liver, kidney, leg muscle, and testis was undertaken. The major CL specie in the heart muscle, leg muscle, liver, and kidney is the (18:2)(4) CL, while liver and kidney also contain a minor specie, (18:2)(3)/(18:1) CL. The major CL specie in testis is the (16:0)(4) CL. The CL species distribution in various organs appeared to be in agreement with prior reports. Overall, proper matrix selection, tissue section handling, instrument tuning, and the inclusion of cesium ion in matrix ensured successful in situ MALDI-MS and MALDI-MS/MS analysis of CL. Upon modification and standardization, this method could be streamlined for rapid pathological diagnosis with short turnaround time in clinical settings.

Animals↗
PubMed2006

In situ structural characterization of glycerophospholipids and sulfatides in brain tissue using MALDI-MS/MS.

Lipids are major structural components of biomembranes. Negatively charged species such as phosphatidylinositol, phosphatidylserine, sulfatides, and the zwitterionic phosphatidylethanolamines are major components of the cytoplasmic surface of the cellular membrane lipid bilayer and play a key role in several receptors signaling functions. Lipids are not just involved in metabolic and neurological diseases; negatively charged lipids in particular play crucial roles in physiological events such as signal transduction, receptors, and enzymatic activation, as well as storage and release of therapeutic drugs and toxic chemicals in the body. Due to the importance of their role in signaling, the field of lipidomics has rapidly expanded in recent years. In the present study, direct probing of tissue slices with negative ion mode matrix assisted laser desorption/ionization mass spectrometry was employed to profile the distribution of lipids in the brain. In total, 32 lipid species consisting of phosphatidylethanolamines, phosphatidylglycerol, phosphatidylinositols, phosphatidylserines, and sulfatides were assigned. To confirm the structure of lipid species, MALDI-MS/MS analysis was conducted. Product-ion spectra obtained in negative ion mode allow for the assignment of the head groups and the fatty acid chains for the lipid species.

Animals↗
PubMed2006

Brain tissue lipidomics: direct probing using matrix-assisted laser desorption/ionization mass spectrometry.

Lipidomics is the new frontier in biomolecular structural studies. Not only are lipids the main components in membranes that define the contours of the cell and its organelles, but they are also used for storage. Lipids form stable noncovalent complexes with proteins as well as with many drugs. Lipids are a storage depot for drugs and certain types of organic molecules. To study lipid composition and distribution, complex and time-consuming techniques are used. However, recent advances in mass spectrometry, mainly matrix-assisted laser desorption/ionization (MALDI) have made it possible to directly probe tissues to study structural components, as well as for the localization of drugs. Direct tissue imaging is a powerful tool as it gives a more complete and accurate structural picture and can trace and follow where drugs localize in tissue with minimal anatomical disruption and a minimum of manipulations. Hence, we believe that in addition to its accuracy and efficiency, this new approach will lead to a better understanding of physiological processes as well as the pathophysiology of disease.

Brain↗
PubMed2006

Particle formation by infrared laser ablation of glycerol: implications for ion formation.

The quantity and size distribution of micrometer-sized particles ejected from thin films of glycerol were measured using light scattering particle sizing. Thin glycerol films were irradiated at atmospheric pressure with an infrared optical parametric oscillator at wavelengths between 2.95 and 3.1 microm. Particulate material resulting from the ablation was sampled directly into a particle-sizing instrument and particles with diameters greater than 500 nm were detected and sized by light scattering. The fluence threshold for particle formation was between 2000 and 3000 J/m2 for all laser wavelengths. At threshold, fewer than 100 particles/cm3 were detected and this value increased to several thousand particles/cm3 at twice the threshold fluence. The average size of the coarse particles ranged from 900 nm to 1.6 microm at threshold and decreased by 10-20% at twice the threshold fluence. The coarse particle formation observations were compared with ion formation behavior in matrix-assisted laser desorption ionization and interpreted in terms of a photomechanical mechanism for material ablation and ion formation.

Atmospheric Pressure↗
PubMed2006

Phosphate stabilization of intermolecular interactions.

Receptor heteromerization is an important phenomenon that results from the interaction of epitopes on two receptors. Previous studies have suggested the possibility of Dopamine D2-NMDA receptors' interaction. We believe that the interaction is through an acidic epitope of the NMDA NR1 subunit (KVNSEEEEEDA) and a basic epitope of the D2 third intracellular loop (VLRRRRKRVN), which was shown to also interact with the Adenosine A2A receptor. In previous work, we highlighted the role of certain amino acid residues, mainly two or more adjacent arginine on one peptide and two or more adjacent glutamate, or aspartate, or a phosphorylated residue on the other in the formation of noncovalent complexes (NCX) between epitopes. In the present work, we use the phosphorylated (KVNSpEEEEEDA), nonphosphorylated (KVNSEEEEEDA) and modified (KVNpSAAAAAAA) forms of the NMDA epitope that possibly interact with the D2 epitope to investigate the gas-phase stability of the NCXs as a function of the nominal energy given to the NCX ion as it enters the collision cell. In addition to theoretical calculations, the experimental data was used to calculate the stability of each electrostatic complex versus that of the dimer of KVNSpEEEEEDA. Our results demonstrate the importance of the phosphate group in stabilizing molecular interactions and that appreciably higher collision energies are required to completely dissociate any of the three different NCX ions that are formed through electrostatic interaction in comparison to the energy required to dissociate the KVNpSEEEEEDA dimer ion, which is mainly kept together by hydrogen bonding. This study emphasizes ionic bonds stability and their importance to protein structure as their potent electrostatic attractions can in the gas-phase surpass the strength of covalent bonds.

Amino Acid Sequence↗
PubMed2006

Decoy peptides that bind dynorphin noncovalently prevent NMDA receptor-mediated neurotoxicity.

Prodynorphin-derived peptides elicit various pathological effects including neurological dysfunction and cell death. These actions are reduced by N-methyl-d-aspartate receptor (NMDAR) but not opioid receptor antagonists suggesting NMDAR-mediation. Here, we show that a conserved epitope (KVNSEEEEEDA) of the NR1 subunit of the NMDAR binds dynorphin peptides (DYNp) noncovalently. Synthetic peptides containing this epitope form stable complexes with DYNp and prevent the potentiation of NMDAR-gated currents produced by DYNp. They attenuate DYNp-evoked cell death in spinal cord and prevent, as well as reverse, DYNp-induced paralysis and allodynia. The data reveal a novel mechanism whereby prodynorphin-derived peptides facilitate NMDAR function and produce neurotoxicity. Furthermore, they suggest that synthetic peptides that bind DYNp, thus preventing their interaction with NMDAR, may be novel therapeutic agents for the treatment of spinal cord injury.

Amino Acid Sequence↗
PubMed2006

IR-MALDI-LDI combined with ion mobility orthogonal time-of-flight mass spectrometry.

Most MALDI instrumentation uses UV lasers. We have designed a MALDI-IM-oTOF-MS which employs both a Nd:YAG laser pumped optical parametric oscillator (OPOTEK, lambda = 2.8-3.2 microm at 20 Hz) to perform IR-LDI or IR-MALDI and a Nd:YLF laser (Crystalaser, lambda = 249 nm at 200 Hz) for the UV. Ion mobility (IM) gives a fast separation and analysis of biomolecules from complex mixtures in which ions of similar chemical type fall along well-defined "trend lines". Our data shows that ion mobility allows multiply charged monomers and multimers to be resolved; thus, yielding pure spectra of the singly charged protein ion which are virtually devoid of chemical noise. In addition, we have demonstrated that IR-LDI produced similar results as IR-MALDI for the direct tissue analysis of phospholipids from rat brain.

Animals↗
PubMed2005

In situ structural characterization of phosphatidylcholines in brain tissue using MALDI-MS/MS.

Phosphatidylcholine (PC) is one of the most abundant classes of phospholipids and is a major component of membranes in biological systems. Recently, PCs have been detected by direct tissue analysis using MALDI-TOFMS. However, these studies did not allow for the structural characterization of PCs in tissue. In the current study, an in situ method for detection and structural analysis of PC species in brain tissue was developed using a MALDI-TOF/TOF mass spectrometer. Initial profiling of lipids in tissue is performed by MALDI-TOFMS, which allows for the assignment of PC species. However, to confirm the structure of the PC species detected in tissue, MALDI-MS/MS analysis was employed. In this work, protonated, sodiated, and potassiated PC species were detected in brain tissue using DHA matrix. MALDI-MS/MS analysis of these species yielded fragments that verified a phosphocholine head group, but did not supply any fragments that would permit the identification of acyl substituents. To obtain more structural information, lithium adducts of PC species were produced using DHA matrix dissolved in 100 mM lithium chloride. MALDI-MS/MS analysis of lithiated PC species produced fragments that allowed for the identification and positional assignment of acyl groups in PC species.

Animals↗
PubMed2005

Localization and analyses of small drug molecules in rat brain tissue sections.

Traditional detection of drugs in tissue requires tissue homogenization, which precludes the mapping and localization of drugs. The use of autoradiography could compensate for such shortcoming. However, it requires expensive custom-synthesized radioactive drugs. Recent improvement in sample preparation for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and MALDI-MS/MS provides an alternative approach for in situ drug detection. In this work, rat brains were collected after intracranial injection of chlorisondamine or intraperitoneal injection of cocaine and snap frozen. MALDI matrixes were applied directly to 14-mum brain cryosections and spectra acquired. The identity of the drugs was further confirmed by MS/MS. Careful matrix selection and tissue preparation allows for the successful detection of drugs and the mapping of their relative abundance across various regions of the brain. This new method is simple, safe, accurate, fast, cost-effective, and low in sample consumption and shows potential for imaging, pharmacokinetics, and toxicology applications.

Animals↗
PubMed2005

Direct profiling of lipid distribution in brain tissue using MALDI-TOFMS.

Recent developments in mass spectrometry have permitted direct analysis of biomolecules in tissue. However, most studies have focused on proteins with emphasis on biomarker discovery. In the present work, matrix-assisted laser desorption/ionization mass spectrometry was used for the direct analysis of lipids in rat cerebellum. The lipid bilayer role as a storage depot for small organic molecules such as therapeutic drugs and pollutants such as DDT, as well as the ability to compare lipid profiles in healthy and diseased animal models, are a few of the many reasons why the direct probing of tissue to determine the qualitative and possibly quantitative lipid content could be a very useful tool. Molecular ions corresponding to cholesterol, phosphatidylcholines, sphingomyelins, and phosphatidylethanolamines were recorded in positive ion mode, while ones corresponding to phosphatidylinositols, sulfatides, and gangliosides were recorded in negative ion mode. Overall, representatives from all major categories of brain lipids including cholesterol, 15 phospholipid species (9 phosphatidylcholines, 1 sphingomyelin, 3 phosphatidylethanolamines, 2 phosphatidylinositols), 10 sulfatides (5 hydroxylated species and 5 nonhydroxylated species), and 7 species of gangliosides were detected.

Animals↗
PubMed2005

Additive effects of endogenous cannabinoid anandamide and ethanol on alpha7-nicotinic acetylcholine receptor-mediated responses in Xenopus Oocytes.

The interaction between the effects of the endogenous cannabinoid receptor agonist anandamide and ethanol on the function of homomeric alpha(7)-nicotinic acetylcholine (nACh) receptors expressed in Xenopus oocytes were investigated using the two-electrode voltage-clamp technique. Anandamide and ethanol reversibly inhibited currents evoked with 100 microM acetylcholine in a concentration-dependent manner. Coapplication of anandamide and ethanol caused a significantly greater inhibition of alpha(7)-nACh receptor function than anandamide or ethanol alone. The IC(50) value of 238 +/- 34 nM for anandamide inhibition decreased significantly to 104 +/- 23 nM in the presence of 30 mM ethanol. The inhibition of alpha(7)-mediated currents by coapplication of anandamide and ethanol was not altered by phenylmethylsulfonyl fluoride, an inhibitor of anandamide hydrolyzing enzyme, or N-(4-hydroxyphenyl)-arachidonylamide, an anandamide transport inhibitor. Analysis of oocytes by matrix-assisted laser desorption/ionization technique indicated that ethanol treatment did not alter the lipid profile of oocytes, and there is negligible, if any, anandamide present in these cells. Results of studies with chimeric alpha(7)-nACh-5-HT(3) receptors comprised of the amino-terminal domain of the alpha(7)-nACh receptor and the transmembrane and carboxyl-terminal domains of 5-HT(3) receptors suggest that although ethanol inhibition of the alpha(7)-nACh receptor is likely to involve the N-terminal region of the receptor, the site of action for anandamide is located in the transmembrane and carboxyl-terminal domains of the receptors. These data indicate that endocannabinoids and ethanol potentiate each other's inhibitory effects on alpha(7)-nACh receptor function through distinct regions of the receptor.

Acetylcholine↗
PubMed2005

Matrix-assisted laser desorption/ionization mass spectrometry of collected bioaerosol particles.

A method was developed for collection and analysis of bioaerosols by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry using a modified Andersen N6 bioaerosol collector. The overall goal of the study was to develop methods for obtaining mass spectra with minimal reagents and treatment steps for potential use in remote collection and analysis systems. Test bioaerosol particles were generated from a nebulized E. coli bacterial suspension and collected on MALDI targets placed in an Andersen N6 single-stage aerosol impactor. The bioaerosols were mixed with matrix either by deposition on a bare target with the matrix solution added later, or by deposition on a target pre-coated with matrix. The matrix compounds alpha-cyano-4-hydroxycinnamic acid (CHCA) and sinapic acid (SA) were tested and the SA matrix was found to give the best results in number of peaks, resolution, and signal-to-noise ratio. Deposition of bioaerosol particles onto the matrix pre-coated target did not produce signal in the m/z region above 1000, but the signal could be recovered with the addition of a 1:1 (v/v) acetonitrile/water solvent. Addition of solvent by pipette to the pre-coated targets after particle deposition recovered signal comparable to the dried-droplet sample preparations, whereas solvent sprayed into the impactor recovered fewer peaks. Deposition on pre-coated targets with post-collection solvent addition was superior to deposition on bare target followed by post-collection addition of matrix solution.

Aerosols↗
PubMed2005

Direct tissue analysis of phospholipids in rat brain using MALDI-TOFMS and MALDI-ion mobility-TOFMS.

After water, lipids are the most common biomolecules found in the brain (12%). A brief perusal of the physiology, anatomy, and pathophysiology of the brain illustrates the importance of lipids. Recent advances in mass spectrometry have allowed the direct probing of tissues. However, most studies have focused on proteins. In the present work, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and MALDI-ion mobility (IM)-TOFMS were employed for direct analysis of phospholipids in rat brain tissue. Molecular ions (MH+) corresponding to phosphatidylcholines, phosphatidylethanolamines, and sphingomyelin, were recorded. When studying pharmacology, we learn that many therapeutic compounds are stored in the body's adipose tissue. MALDI-TOFMS and MALDI- IM-TOFMS were thus used to analyze rat brain tissue with chlorisondamine added directly onto the tissue slice. With both techniques, noncovalent complexes between the tissue phospholipids and chlorisondamine were detected. In addition, MALDI-IM-TOFMS of noncovalent complexes between phospholipids and chlorisondamine displayed a mobility between that of an isobaric lipid and peptide.

Animals↗
PubMed2004

Matrix-implanted laser desorption/ionization mass spectrometry.

The implantation of low-velocity massive gold clusters is shown to be a method of choice for homogeneous incorporation of a metallic matrix into the near-surface region of a solid biopolymer for subsequent laser desorption/ionization (LDI) MS analysis. Matrix implanted (MI)LDI spectra from cluster-implanted pure test peptide or tissue exhibit molecular ion peaks similar to those observed by matrix-assisted LDI. Moreover, the ion emission is very reproducible from any spot on the surface of these test samples. MILDI promises to be a powerful technique for mass spectrometric analysis of native biological samples as demonstrated by the first results on rat brain tissues.

Animals↗
PubMed2004

On-line laser desorption/ionization mass spectrometry of matrix-coated aerosols.

Matrix-assisted laser desorption/ionization (MALDI) was used for the on-line analysis of single particles. An aerosol was generated at atmospheric pressure and particles were introduced into a time-of-flight (TOF) mass spectrometer through a single-stage differentially pumped capillary inlet. Prior to entering the mass spectrometer, a matrix was added to the particles using a heated saturator and condenser. A liquid matrix, 3-nitrobenzyl alcohol (NBA), and a solid matrix, picolinic acid (PA), were used. Particles were ablated with a 351 nm excimer laser and the resulting ions were mass-separated in a two-stage reflectron TOF mass spectrometer. Aerosol particles containing the biomolecules erythromycin and gramicidin S were analyzed with and without the matrix addition step. The addition of NBA to the particles resulted in mass spectra that contained an intact molecular ion mass peak. In contrast, PA-coated particles did not yield molecular ion peaks from matrix-coated particles.

Aerosols↗
PubMed2002

Matrix addition by condensation for matrix-assisted laser desorption/ionization of collected aerosol particles.

Condensation of an ultraviolet absorbing liquid matrix onto aerosol particles was used to enhance the ionization efficiency of large molecules. Laboratory-generated particles were coated with matrix, deposited on a sample target, and analyzed by laser desorption mass spectrometry with no other matrix addition. The aerosol was generated in a Collison nebulizer, and the particles were dried in a diffusion dryer before entering a heated region saturated with the liquid matrix 3-nitrobenzyl alcohol (NBA) and then entering a cooled condensation region. Matrix-coated particles were collected on a sample target and analyzed using a 337-nm laser and a time-of-flight mass spectrometer. Particles containing the peptides gramicidin S and gramicidin D were analyzed both with and without the matrix addition step. Condensation addition of matrix increased the biomolecule ion signal and resulted in mass spectra with less fragmentation and low-mass ion interference.

Aerosols↗
PubMedDate not supplied

Study of the fragmentation patterns of the phosphate-arginine noncovalent bond.

Our previous work has highlighted the role of certain amino acid residues, mainly two or more adjacent arginine on one peptide and two or more adjacent glutamate, or aspartate, or a phosphorylated residue on the other in the formation of noncovalent complexes (NCX) between peptides. In the present study, we employ ESI-MS to investigate the gas-phase stability and dissociation pathways of the NCX of a basic peptide VLRRRRKRVN, an epitope from the third intracellular loop of the dopamine D(2) receptor, with the phosphopetide SVSTDpTpSAE, an epitope from the cannabinoid CB1 carboxyl terminus. ESI-MS/MS analysis of the NCX between VLRRRRKRVN and SVSTDpTpSAE suggests two dissociation pathways for the NCX. The major pathway is the disruption of the electrostatic interactions between the Arg residues and the phosphate groups, while an alternative pathway is also recorded, in which the complex is dissociated along the covalent bond between the oxygen from either Thr or Ser and HPO(3). To verify the alternative pathway, we have used an ion trap instrument to conduct MS(3) analysis on the product ions of both dissociation pathways.

Amino Acid Sequence↗