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Mark Bradley

Publications and source records attributed to Mark Bradley.

At least 19 recordsLinked to original sources
PubMed2003

Synthesis and evaluation of fluorescent probes for the detection of calpain activity.

Two new probes for the detection of calpain I activity based on fluorescence resonance energy transfer technology have been synthesized and evaluated. The probes incorporated the cleavage site present in alpha-spectrin, a naturally occurring substrate of calpain I. The design of the internally quenched substrates is such that the calpain-sensitive bond of the peptides (between the Tyr-Gly residues) is located centrally between the donor and the quencher chromophores. The calpain assay protocol is capable of detecting enzymatic activity in the nanomolar region.

Amino Acid Sequence↗
PubMed2003

Characterisation of a novel class of polyamine-based neuroprotective compounds.

Prolonged cerebral ischaemia initiates complex intra- and inter-cellular signalling cascades ultimately resulting in neuronal death. Well-characterised mediators of ischaemic cell death are glutamate, free radicals and nitric oxide. Many drugs that block these mechanisms are neuroprotective in vitro, but have unfavourable side-effect profiles in man. We have recently demonstrated that the compound L-arginyl-3,4-spermidine (L-Arg3,4) is neuroprotective in vitro through an interaction with several of these mechanisms, and prevents ischaemic neurodegeneration in vivo with no gross side effects. In this study, we have used solid-phase combinatorial chemistry, to synthesise a number of analogues of L-Arg3,4, and investigate the structure-activity relationship using an in vitro, organotypic hippocampal slice culture model of cerebral ischaemia. A number of molecular features were identified which were essential for the neuroprotective activity including the requirement for a positive charge and an amino acid in the L-configuration. Relatively minor alterations to both the terminal arginine and polyamine moieties significantly attenuated neuroprotective efficacy. Our data implies that these compounds are neuroprotective through a currently undefined mechanism rather than non-specific ionic interactions described previously for other polyamine-containing compounds.

Animals↗
PubMed2003

Mild and highly chemoselective oxidation of thioethers mediated by Sc(OTf)3.

[reaction: see text] Catalytic Sc(OTf)(3) greatly increases the efficiency of hydrogen peroxide mediated monooxidation of alkyl-aryl sulfides and methyl cysteine containing peptides. The method is high yielding, compatible with many widely used protecting groups, suitable for solid-phase applications and proceeds with minimum over-oxidation.

Journal Article↗
PubMed2003

Recycling solid supports--a head-to-tail linker.

The concept of a 'head-to-tail linker' designed to allow the regeneration and reuse of a variety of solid supports is introduced. The synthesis of this linker, its coupling to various solid supports, its application in a number of standard solid phase reactions and resin regeneration are presented.

Combinatorial Chemistry Techniques↗
PubMed2003

Loading amplification of radiation grafted polymers (crowns and lanterns) and their application in the solid-phase synthesis of hydantoin libraries.

Solid-phase dendrimer chemistry using a symmetrical 1 --> 3 C-branched isocyanate monomer was used to prepare radiation-grafted polymers with enhanced loading. After evaluation of the physical and chemical properties of these new high-loading supports, they were tested in the multiple parallel synthesis of hydantoins.

Combinatorial Chemistry Techniques↗
PubMed2002

Enzyme accessibility and solid supports: which molecular weight enzymes can be used on solid supports? An investigation using confocal Raman microscopy.

The accessibility of various solid supports (TentaGel, PEGA 1900, and beaded controlled pore glasses (CPGs)) to a range of enzymes was investigated. The different beaded materials were loaded with the peptide 4-cyanobenzamide-Gly-Pro-Leu-Gly-Leu-Phe-Ala-Arg-OH and incubated with the enzymes MMP-12 (22 kDa), thermolysin (35 kDa), MMP-13 (42.5 kDa), clostridium collagenase (68 kDa), and NEP (90 kDa). The absence/presence of the cyano stretching frequency was measured by means of confocal Raman microscopy. It was found that none of the investigated enzymes could enter the polymer matrices of TentaGel. PEGA 1900 was compatible only with the two smallest enzymes, while beaded CPG was successful even with NEP (90 kDa), proving its superiority over other materials in terms of bio-compatibility.

Biocompatible Materials↗
PubMed2002

A controlled trial of methadone treatment combined with directly observed isoniazid for tuberculosis prevention in injection drug users.

Substance abuse is associated with high risk for tuberculosis (TB) and poor adherence to medication regimens. This study compared completion rates for isoniazid (INH) preventive therapy for injection drug users (IDUs) randomly assigned to methadone treatment combined with directly observed preventive treatment (DOPT) versus those assigned to routine TB clinic referral without methadone treatment. One hundred and eleven opioid-dependent patients with latent TB were assigned to one of three 6-month treatment conditions: standard methadone treatment including substance abuse counseling combined with daily INH DOPT (n=37); minimal methadone treatment without counseling, also combined with daily INH DOPT (n=35); or routine care referral to TB clinic for monthly INH supplies without DOPT and without methadone treatment (n=39). INH completion rates were 77.1% for minimal methadone and 59.5% for standard methadone, as compared with only 13.5% for routine care (P<0.0001). Mean duration of INH treatment retention was 5.7, 5.0 and 1.6 months, respectively (P<0.0001). TB incidence at 4-year follow-up was 0 of 54 subjects who completed preventive therapy versus 2 of 57 who failed to complete. One of these two had been assigned to routine care, and the other to minimal methadone. In conclusion, INH retention time and completion rates were significantly improved by methadone treatment combined with observed INH, whether or not substance abuse counseling was provided. The results of this study indicate that methadone treatment offers clear public health benefits when it is used to deliver preventive medical services.

Adult↗
PubMed2002

Solid supports for combinatorial chemistry.

Over the past year, numerous techniques have been used to study the resins commonly utilised in solid-phase synthesis to allow a greater understanding of the chemical nature and the physical properties of the supports. In addition, to overcome some of the drawbacks of existing materials, several new resins and new methods of handling solid supports have been developed. New methodologies have also been introduced to simplify the preparation of solid supports.

Combinatorial Chemistry Techniques↗
PubMed2002

L-arginyl-3,4-spermidine is neuroprotective in several in vitro models of neurodegeneration and in vivo ischaemia without suppressing synaptic transmission.

1. Stroke is the third most common cause of death in the world, and there is a clear need to develop new therapeutics for the stroke victim. To address this need, we generated a combinatorial library of polyamine compounds based on sFTX-3.3 toxin from which L-Arginyl-3,4-Spermidine (L-Arg-3,4) emerged as a lead neuroprotective compound. In the present study, we have extended earlier results to examine the compound's neuroprotective actions in greater detail. 2. In an in vitro ischaemia model, L-Arg-3,4 significantly reduced CA1 cell death when administered prior to induction of 60 min of ischaemia as well as when administered immediately after ischaemia. Surprisingly, L-Arg-3,4 continued to prevent cell death significantly when administration was delayed for as long as 60 min after ischaemia. 3. L-Arg-3,4 significantly reduced cell death in excitotoxicity models mediated by glutamate, NMDA, AMPA, or kainate. Unlike glutamate receptor antagonists, 300 microM L-Arg-3,4 did not suppress synaptic transmission as measured by evoked responses in acute hippocampal slices. 4. L-Arg-3,4 provided significant protection, in vitro, in a superoxide mediated injury model and prevented an increase of superoxide production after AMPA or NMDA stimulation. It also decreased nitric oxide production after in vitro ischaemia and NMDA stimulation, but did so without inhibiting nitric oxide synthase directly. 5. Furthermore, L-Arg-3,4 was significantly neuroprotective in an in vivo model of global forebrain ischaemia, without any apparent neurological side-effects. 6. Taken together, these results demonstrate that L-Arg-3,4 is protective in several models of neurodegeneration and may have potential as a new therapeutic compound for the treatment of stroke, trauma, and other neurodegenerative diseases.

Animals↗
PubMed2002

The combinatorial centre of excellence - a unique industrial academic partnership.

The Combinatorial Centre of Excellence (CCE) offers a unique opportunity for the exploitation of a broad range of combinatorial methodologies. Many areas of activity are under investigation, including high-throughput X-ray of small molecules, parallel polymer chemistry and the development of new multi-component reactions.

Academies and Institutes↗
PubMed1999

Solid-Phase Synthesis of Tyrosine Peptide Aldehydes. Analogues of (S)-MAPI.

We report an efficient solid-phase synthesis of C-terminal tyrosine peptide aldehydes based on the HIV protease inhibitors (S)-MAPI and GE 20372 A. Our strategy consisted of anchoring the side chain of Dde-Tyrosinol (5) onto the brominated Wang linker derivative ((4-bromomethyl)-phenoxy-allyl acetate) (6) to give after ester hydrolysis the N(alpha)-(Dde)-O-(4-methylphenoxyacetic acid)-L-Tyrosinol template (8). This was attached to aminomethyl resin and elongated using standard Fmoc protocols. Importantly there was no evidence of esterification side reactions. The unsymmetrically substituted urea linkage of the (S)-MAPI family was incorporated using the N(alpha)-(4-nitrophenyloxycarbonyl)amino acid tert-butyl esters following which the protected tetrapeptide alcohol immobilized on the solid support was oxidized to its corresponding aldehyde using sulfur trioxide-pyridine. The efficiency and reliability of the oxidation step was dramatically improved by the incorporation of a small PEG-spacer between the linker and the solid support. The tetrapeptides 12a and 12b were cleaved by acidolysis, purified by RP HPLC, and isolated in high yield and purity, demonstrating the success of the whole synthetic process.

Journal Article↗