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1.  PHC3 SAM linker allows open-ended polymerization of PHC3 SAM 
Biochemistry  2012;51(27):5379-5386.
Sterile alpha motifs (SAMs) are frequently found in eukaryotic genomes. An intriguing property of many SAMs is their ability to self-associate, forming an open-ended polymer structure whose formation has been shown to be essential for the function of the protein. What remains largely unresolved is how polymerization is controlled. Previously, we had determined that the stretch of unstructured residues N-terminal to the SAM of a Drosophila protein called Polyhomeotic (Ph), a member of the Polycomb Group (PcG) of gene silencers, plays a key role in controlling Ph SAM polymerization. Ph SAM with its native linker created shorter polymers compared to Ph SAM attached to either a random linker or no linker. Here, we show that the SAM linker for the human Ph ortholog, Polyhomeotic homolog 3 (PHC3), also controls PHC3 SAM polymerization but does so in the opposite fashion. PHC3 SAM with its native linker allows longer polymers to form compared to when attached to a random linker. Attaching the PHC3 SAM linker to Ph SAM also resulted in extending Ph SAM polymerization. Moreover, in the context of full-length Ph protein, replacing the SAM linker with PHC3 SAM linker, intended to create longer polymers, resulted in greater repressive ability for the chimera compared to wild-type Ph. These findings show that polymeric SAM linkers evolved to modulate a wide dynamic range of SAM polymerization abilities and suggest that rationally manipulating the function of SAM containing proteins through controlling their SAM polymerization may be possible.
PMCID: PMC4045017  PMID: 22724443
2.  Identification of nucleic acid binding residues in the FCS domain of the Polycomb Group protein Polyhomeotic 
Biochemistry  2011;50(22):4998-5007.
Polycomb Group (PcG) proteins maintain the silent state of developmentally important genes. Recent evidence indicates that non-coding RNAs also play an important role in targeting PcG proteins to chromatin and PcG mediated chromatin organization, although the molecular basis for how PcG and RNA function in concert remains unclear. The Phe-Cys-Ser (FCS) domain, named for three consecutive residues conserved in this domain, is a 30 - 40 residue Zn2+ binding motif found in a number of PcG proteins. The FCS domain has been shown to bind RNA in a non-sequence specific manner, but how it does so is not known. Here, we present the three dimensional structure of the FCS domain from human Polyhomeotic homolog 1 (hPh1) determined using multi-dimensional NMR methods. Chemical shift perturbations upon the addition of RNA and DNA resulted in the identification of Lys 816 as a potentially important residue required for nucleic acid binding. The role played by this residue in Polyhomeotic function was demonstrated in a transcription assay carried out in Drosophila S2 cells. Mutation of the Arg residue to Ala in the Drosophila Polyhomeotic (Ph) protein, that is equivalent to hPh1 Lys 816, was unable to repress transcription of a reporter gene to the level of wild-type Ph. These results suggest that direct interaction between the Ph FCS domain and nucleic acids is required for Ph mediated repression.
PMCID: PMC3938326  PMID: 21351738
3.  Consensus Treatments for Moderate Juvenile Dermatomyositis: Beyond the First Two Months 
Arthritis care & research  2012;64(4):546-553.
To use consensus methods and the considerable expertise contained within the Children’s Arthritis and Rheumatology Research Alliance (CARRA) organization, to extend the 3 previously developed treatment plans for moderate juvenile dermatomyositis (JDM) to span the full course of treatment.
A consensus meeting was held in Chicago on April 23–24, 2010 involving 30 pediatric rheumatologists and 4 lay participants. Nominal group technique was used to achieve consensus on treatment plans which represented typical management of moderate JDM. A pre-conference survey of CARRA, completed by 151/272 (56%) members, was used to provide additional guidance to discussion.
Consensus was reached on timing and rate of steroid tapering, duration of steroid therapy, and actions to be taken if patients were unchanged, worsening, experiencing medication side effects or disease complications. Of particular importance, a single, consensus steroid taper was developed.
We were able to develop consensus treatment plans which describe therapy for moderate JDM throughout the treatment course. These treatment plans can now be used clinically, and data collected prospectively regarding treatment effectiveness and toxicity. This will allow comparison of these treatment plans and facilitate the development of evidence-based treatment recommendations for moderate JDM.
PMCID: PMC3315594  PMID: 22076847
4.  Disease Activity, Proteinuria, and Vitamin D Status in Children with Systemic Lupus Erythematosus and Juvenile Dermatomyositis 
The Journal of Pediatrics  2011;160(2):297-302.
To evaluate relationships between vitamin D, proteinuria, and disease activity in pediatric systemic lupus erythematosus (SLE) and juvenile dermatomyositis (JDM).
Study design
Multiple linear regression was used to associate subject-reported race, sunscreen use, and vitamin D intake with physician-assessed disease activity and serum 25-hydroxyvitamin D [25(OH)D] in subjects with pediatric SLE (n = 37) or JDM (n = 21). Serum 25(OH)D was correlated with urinary vitamin D binding protein/creatinine ratio (DBP/C) and other indicators of proteinuria.
Serum 25(OH)D levels in subjects with SLE were inversely associated with the natural log of urinary DBP/C (r = −0.63, p < 0.001) and urine protein to creatinine ratio (r = −0.60, p<0.001), with an adjusted mean 10.9 (95% CI 5.1, 16.8) ng/mL decrease in 25(OH)D for those with proteinuria. Excluding subjects with proteinuria, serum 25(OH)D levels were inversely associated with disease activity in JDM, but not in SLE. Overall, 66% of all subjects were taking concurrent corticosteroids, but this was not associated with 25(OH)D levels.
Low serum 25(OH)D in patients with SLE is associated with proteinuria and urinary DBP. Vitamin D deficiency is associated with disease activity in patients with JDM and SLE; this relationship in SLE may be confounded by proteinuria.
PMCID: PMC3258326  PMID: 21924736
25-hydroxyvitamin D; vitamin D binding protein
9.  The social value of a QALY: raising the bar or barring the raise? 
Since the inception of the National Institute for Health and Clinical Excellence (NICE) in England, there have been questions about the empirical basis for the cost-per-QALY threshold used by NICE and whether QALYs gained by different beneficiaries of health care should be weighted equally. The Social Value of a QALY (SVQ) project, reported in this paper, was commissioned to address these two questions. The results of SVQ were released during a time of considerable debate about the NICE threshold, and authors with differing perspectives have drawn on the SVQ results to support their cases. As these discussions continue, and given the selective use of results by those involved, it is important, therefore, not only to present a summary overview of SVQ, but also for those who conducted the research to contribute to the debate as to its implications for NICE.
The issue of the threshold was addressed in two ways: first, by combining, via a set of models, the current UK Value of a Prevented Fatality (used in transport policy) with data on fatality age, life expectancy and age-related quality of life; and, second, via a survey designed to test the feasibility of combining respondents' answers to willingness to pay and health state utility questions to arrive at values of a QALY. Modelling resulted in values of £10,000-£70,000 per QALY. Via survey research, most methods of aggregating the data resulted in values of a QALY of £18,000-£40,000, although others resulted in implausibly high values. An additional survey, addressing the issue of weighting QALYs, used two methods, one indicating that QALYs should not be weighted and the other that greater weight could be given to QALYs gained by some groups.
Although we conducted only a feasibility study and a modelling exercise, neither present compelling evidence for moving the NICE threshold up or down. Some preliminary evidence would indicate it could be moved up for some types of QALY and down for others. While many members of the public appear to be open to the possibility of using somewhat different QALY weights for different groups of beneficiaries, we do not yet have any secure evidence base for introducing such a system.
PMCID: PMC3023672  PMID: 21223540
10.  The Glycinergic System in Human Startle Disease: A Genetic Screening Approach 
Human startle disease, also known as hyperekplexia (OMIM 149400), is a paroxysmal neurological disorder caused by defects in glycinergic neurotransmission. Hyperekplexia is characterised by an exaggerated startle reflex in response to tactile or acoustic stimuli which first presents as neonatal hypertonia, followed in some with episodes of life-threatening infantile apnoea. Genetic screening studies have demonstrated that hyperekplexia is genetically heterogeneous with several missense and nonsense mutations in the postsynaptic glycine receptor (GlyR) α1 subunit gene (GLRA1) as the primary cause. More recently, missense, nonsense and frameshift mutations have also been identified in the glycine transporter GlyT2 gene, SLC6A5, demonstrating a presynaptic component to this disease. Further mutations, albeit rare, have been identified in the genes encoding the GlyR β subunit (GLRB), collybistin (ARHGEF9) and gephyrin (GPHN) – all of which are postsynaptic proteins involved in orchestrating glycinergic neurotransmission. In this review, we describe the clinical ascertainment aspects, phenotypic considerations and the downstream molecular genetic tools utilised to analyse both presynaptic and postsynaptic components of this heterogeneous human neurological disorder. Moreover, we will describe how the ancient startle response is the preserve of glycinergic neurotransmission and how animal models and human hyperekplexia patients have provided synergistic evidence that implicates this inhibitory system in the control of startle reflexes.
PMCID: PMC2854534  PMID: 20407582
glycine; hyperekplexia; receptor; transporter; mutation
11.  Reflections of a president 
Sexually Transmitted Infections  2006;82(2):99-100.
PMCID: PMC2564702  PMID: 16581730
12.  Purification and crystallization of complexes modeling the active state of the fragile histidine triad protein 
Protein engineering  1997;10(12):1461-1463.
Fragile histidine triad protein (Fhit) is a diadenosine triphosphate (ApppA) hydrolase encoded at the human chromosome 3 fragile site which is frequently disrupted in tumors. Reintroduction of FHIT coding sequences to cancer cell lines with FHIT deletions suppressed the ability of these cell lines to form tumors in nude mice even when the reintroduced FHIT gene had been mutated to allow ApppA binding but not hydrolysis. Because this suggested that the tumor suppressor activity of Fhit protein depends on substrate-dependent signaling rather than ApppA catabolism, we prepared two crystalline forms of Fhit protein that are expected to model its biologically active, substrate bound state. Wild-type and the His96Asn forms of Fhit were overexpressed in Escherichia coli, purified to homogeneity and crystallized in the presence and absence of ApppA and an ApppA analog. Single crystals obtained by vapor diffusion against ammonium sulfate diffracted Xrays to beyond 2.75 Å resolution. High quality native synchrotron X-ray data were collected for an orthorhombic and a hexagonal crystal form.
PMCID: PMC2556046  PMID: 9543008
Fhit; nucleotide-binding; tumor-suppressor; ApppA
13.  Rising rates of HIV infection 
BMJ : British Medical Journal  2005;330(7487):320-321.
PMCID: PMC548714  PMID: 15705670

Results 1-14 (14)