Biomedical subjects

Christopher Jones

Publications and source records attributed to Christopher Jones.

44 records · Page 3Linked to original sources

PubMed2002

Expression, purification, crystallization and preliminary characterization of an HHED aldolase homologue from Escherichia coli K12.

An ORF designated b2245 (yfaU) in the Escherichia coli K12 genome sequence, identified as an HHED aldolase homologue, was cloned into the high-expression plasmid pT7-7 and overexpressed in E. coli B835(DE3). The enzyme was purified in three steps to 95% purity prior to crystallization. Crystals were obtained by the hanging-drop vapour-diffusion method at 277 K from a number of screening conditions. Crystals suitable for structural studies were grown from solutions containing 0.4 M ammonium dihydrogen phosphate and grew to a maximum dimension of approximately 0.5 mm. Diffraction data to 1.7 A were collected using an in-house Cu Kalpha radiation source at 100 K. The crystals belong to space group C222(1), with unit-cell parameters a = 105.1, b = 136.6, c = 123.1 A. A 90% complete data set was collected to 1.78 A from a single native crystal using in-house facilities.

Aldehyde-Lyases↗

PubMed2002

Confirmation of the D configuration of the 2-substituted arabinitol 1-phosphate residue in the capsular polysaccharide from Streptococcus pneumoniae Type 17F.

The absolute configuration of the 2-substituted arabinitol 1-phosphate residue present in the repeating unit of the capsular polysaccharide (CPS) from Streptococcus pneumoniae Type 17F is confirmed as D, based on a comparison of proton and carbon chemical shifts in a synthetic oligosaccharide and in an oligosaccharide derived from the CPS by degradation.

Carbohydrate Conformation↗

PubMed2002

Use and validation of NMR assays for the identity and O-acetyl content of capsular polysaccharides from Neisseria meningitidis used in vaccine manufacture.

We describe a validated NMR (nuclear magnetic resonance) spectroscopic assay for the identity of the capsular polysaccharides (CPSs) from Neisseria meningitidis Groups A, C, W135 and Y used in vaccine manufacture, and to determine the proportion of residues carrying an O-acetyl substituent. Proof of structural identity and quantitation of the O-acetyl content are key control parameters for these vaccines. The meningococcal CPSs have variable levels of O-acetylation, present at multiple sites in the repeat unit, leading to complex NMR spectra. Base-catalysed de-O-acetylation of the Groups A, C, W135 and Y CPSs yields simplified and reproducible spectra suitable for comparison with reference data. The degree of O-acetylation of the original CPS can be determined by integration of the acetate anion resonance and a suitable resonance from the saccharide moiety. The assay was validated using 46 independent samples from five manufacturers, and is shown to be robust and reproducible.

Acetylation↗

PubMed2002

Induced osteogenesis by periosteal distraction.

PURPOSE: The purpose of this project was to evaluate a novel technique for inducing osteogenesis through periosteal distraction in a rabbit model. MATERIALS AND METHODS: A periosteal distraction device was rigidly fixed to the lateral surface of the mandible in 10 adult rabbits. Periosteal distraction was started 7 days after placement of the periosteal distraction device. The periosteum was distracted 7 mm over 15 days. The unoperated, contralateral side of the mandible served as the control. The animals were killed at postoperative days 28, 35, 42, and 56. The specimens were then fixed, decalcified, and stained with hematoxylin and eosin. Histologic examination and histomorphometric analysis were performed on all specimens. RESULTS: Nine of 10 periosteal distraction devices remained rigidly fixed to the lateral surface of the mandible. On postoperative day 28, the histologic specimen from the experimental side showed periosteal proliferation and an increase in the number of osteoblasts. On postoperative days 35, 42, and 56, the experimental side showed an increase in the number of osteocytes per unit area, collagen fibers parallel to the vector of distraction, islands of osteoblasts surrounded by newly formed bone, and maturation of bone. An average of 2.86 +/- 0.56 mm of new bone height was formed. CONCLUSION: We report on a novel technique for generating bone by periosteal distraction. Our histologic analysis showed proliferation of the periosteum, an increase in the number of osteoblasts and osteogenesis.

Animals↗

PubMed2002

Molecular analysis of a novel family of complex glycoinositolphosphoryl ceramides from Cryptococcus neoformans: structural differences between encapsulated and acapsular yeast forms.

Complex glycoinositolphosphoryl ceramides (GIPCs) have been purified from a pathogenic encapsulated wild-type (WT) strain of Cryptococcus neoformans var. neoformans and from an acapsular mutant (Cap67). The structures of the GIPCs were determined by a combination of tandem mass spectrometry, nuclear magnetic resonance spectroscopy, methylation analysis, gas chromatography-mass spectrometry, and chemical degradation. The main GIPC from the WT strain had the structure Manp(alpha1-3)[Xylp(beta1-2)] Manp(alpha1-4)Galp(beta1-6)Manp(alpha1-2)Ins-1-phosphoryl ceramide (GIPC A), whereas the compounds from the acapsular mutant were more heterogeneous in their glycan chains, and variants with Manp(alpha1-6) (GIPC B), Manp(alpha1-6) Manp(alpha1-6) (GIPC C), and Manp(alpha1-2)Manp(alpha1-6)Manp(alpha1-6) (GIPC D) substituents linked to the nonreducing terminal mannose residue found in the WT GIPC A were abundant. The ceramide moieties of C. neoformans GIPCs were composed of a C(18) phytosphingosine long-chain base mainly N-acylated with 2-hydroxy-tetracosanoic acid in the WT GIPC while in the acapsular Cap67 mutant GIPCs, as well as 2-hydroxy-tetracosanoic acid, the unusual 2,3-dihydroxy-tetracosanoic acid was characterized. In addition, structural analysis revealed that the amount of GIPC in the WT cells was fourfold less of that in the acapsular mutant.

Carbohydrate Conformation↗

PubMed2002

Immunogenicity in a mouse model of a conjugate vaccine made with a synthetic single repeating unit of type 14 pneumococcal polysaccharide coupled to CRM197.

Oligosaccharides (OSs) related to the pneumococcal type 14 capsular polysaccharide (Pn14PS) were studied for their ability to inhibit the binding between anti-PS14 antisera and native PS14. A synthetic tetrasaccharide corresponding to the repeating unit of the Pn14PS, a hexasaccharide mimic, and an octasaccharide fragment obtained by Pn14PS depolymerization were good inhibitors. CRM197 conjugates of the tetrasaccharide and an octasaccharide mimic were prepared by using either adipic acid diester or diethyl squarate linkers. The conjugate with the tetrasaccharide chains induced anti-Pn14PS antibodies when injected subcutaneously into mice, as determined by an enzyme-linked immunosorbent assay, and antibody titers increased with oligosaccharide loading. The adipic acid-linked tetrasaccharide conjugates elicited higher antibody titers than those prepared with a squarate spacer. The lower anti-Pn14PS antibody response of the octasaccharide mimic conjugate indicates the importance of the backbone galactose residue for an appropriate antibody response. The OS-CRM197 conjugate prepared from a single repeat unit of the Pn14PS is a potential vaccine candidate.

Animals↗

PubMed2002

Developing a model to enhance the capacity of statutory organisations to engage with lay communities.

OBJECTIVE: To understand the processes that constrain the capacity of statutory organisations to work effectively with lay communities and to develop a model to enhance their capacity to do so. METHODS: The research consisted of three elements: a review of relevant literature; in-depth interviews with a purposive sample of people who had recently been involved in community-statutory sector partnership; and a deliberative workshop involving ten expert witnesses, selected to reflect a range of sectors and levels within organisations. RESULTS: Many factors contribute to a lack of effective strategic partnerships between lay communities and statutory organisations. These factors fall into five domains: the community's capacity to engage; the skills and competencies of organisational staff; the dominant professional service culture; the overall organisational ethos and culture; and the dynamics of the local and national political systems. A model of the relationships and/or interaction between these domains is postulated. There is potential for testing this model with statutory organisations to see whether it concurs with their reality and whether it is enhancing their organisational capacity. CONCLUSIONS: Commonly occurring constraints to effective partnerships between statutory organisations and lay communities need to be identified and addressed by applying a dynamic model of the type presented here.

Community Health Planning↗

PubMedDate not supplied

Genetics: overview and issues in child health.

When the normal growth and development of a child fails it can cause major developmental and clinical problems. It is important that nurses understand the rationale behind genetic tests and therapies for diseases such as cystic fibrosis and childhood cancers.

Base Pairing↗