Biomedical subjects

R J Ward

Publications and source records attributed to R J Ward.

At least 19 recordsLinked to original sources

PubMed2006

Differences in trabecular structure between knees with and without osteoarthritis quantified by macro and standard radiography, respectively.

OBJECTIVE: To compare the sensitivity of standard and macro-radiography for quantifying cancellous bone differences between subjects with and without medial compartment knee osteoarthritis (OA). METHODS: Patients with medial compartment knee OA (n=24) and non-OA reference subjects (n=10) had a standard and a macro-radiograph (x4 magnification) of one knee. Fractal Signature Analysis (FSA), a computerised image analysis technique, measured differences in cancellous bone structure between OA and non-OA tibiae in all radiographs. RESULTS: Compared to non-OA, FSA of vertical trabeculae in macro-radiographs increased significantly (P<0.05) in the OA group at several trabecular widths (0.30-0.60mm, 0.7 mm, 0.98-1.14 mm) and in standard radiographs at a single trabecular width (0.48 mm). CONCLUSION: Compared to standard radiography, increased spatial resolution of macro-radiography allowed greater detection of trabecular bone differences between OA and non-OA knees. Nonetheless, difference was also detected in standard radiographs.

Adult↗

PubMed2006

Osteophytes, juxta-articular radiolucencies and cancellous bone changes in the proximal tibia of patients with knee osteoarthritis.

OBJECTIVE: To determine differences in tibial cancellous bone organisation in knee osteoarthritis (OA) between the central weight-bearing region and juxta-articular radiolucencies adjacent to small, medium or large marginal osteophytes. METHODS: Patients with medial compartment OA (n = 60; F = 39), mean (SD) age 60.0 (9.7) years, and non-OA reference subjects (n = 21; F = 5), mean (SD) age 36.8 (11.5) years, had x4 macroradiographs digitised by laser scanner. Using a modified Osteoarthritis Research Society (OARS) Atlas, right and/or left knees were graded according to marginal osteophyte size into those with small (n = 30), medium (n = 30) or large (n = 27) marginal osteophytes, identified as OPH1, OPH2 and OPH3, respectively. Non-OA knees (n = 30) were anatomically normal. Computerised method of Fractal Signature Analysis (FSA) quantified differences in cancellous bone structure between non-OA and osteophyte subgroups at two regions of interest (ROIs); central weight-bearing and tibial margin. RESULTS: Compared to non-OA, vertical trabecular number increased significantly (P < 0.05) in all osteophyte subgroups (width range 0.12-1.14 mm) within both ROIs. In OPH3, this increase was significantly (P < 0.05) greater compared to OPH2 in the central ROI, and to OPH2 and OPH1 in the marginal ROI at most trabecular widths (0.12-1.14 mm). In the marginal ROI, compared to non-OA, horizontal trabeculae number decreased in all osteophyte subgroups. This decrease was significantly greater in OPH3 compared to OPH2 and OPH1 at small to medium trabecular widths (0.12-0.54 mm). CONCLUSION: Compared to disease associated bone loss at the central ROI of the tibia, the extent of juxta-articular bone loss appears to be associated with the size of the marginal osteophytes.

Adult↗

PubMed2006

A micelle nucleation model for the interaction of dodecyl sulphate with Lys49-phospholipases A(2).

Bothropstoxin-I (BthTx-I) is a Lys49-PLA(2) from the venom of Bothrops jararacussu that lacks detectable catalytic activity, yet causes rapid Ca(2+)-independent membrane damage. With the aim of understanding the interaction between BthTx-I and amphiphilic molecules, we have studied the interaction of sodium dodecyl sulphate (SDS) with the protein. Circular dichroism and attenuated total reflection Fourier-transform infrared spectra of BthTx-I reveal changes in the alpha-helical organization of the protein at an SDS/BthTx-I molar ratio of 20-25. At SDS/BthTx-I ratios of 40-45 the alpha-helices return to a native-like conformation, although fluorescence emission anisotropy measurements of 2-amino-N-hexadecyl-benzamide (AHBA) demonstrate that the total SDS is below the critical micelle concentration when this transition occurs. These results may be interpreted as the result of SDS accumulation by the BthTx-I homodimer and the formation of a pre-micelle SDS/BthTx-I complex, which may subsequently be released from the protein surface as a free micelle. Similar changes in the alpha-helical organization of BthTx-I were observed in the presence of dipalmitoylphosphatidylcholine liposomes, suggesting that protein structure transitions coupled to organization changes of bound amphiphiles may play a role in the Ca(2+)-independent membrane damage by Lys49-PLA(2)s.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2006

A 2 yr longitudinal radiographic study examining the effect of a bisphosphonate (risedronate) upon subchondral bone loss in osteoarthritic knee patients.

OBJECTIVES: To determine whether risedronate (RIS) slows down trabecular bone loss in the medial compartment of the proximal tibia, a characteristic of patients with progressive knee osteoarthritis (OA). METHODS: Initially, 100 patients were randomly selected from each treatment group (each N approximately 300) comprising placebo and RIS 5 mg/day, 15 mg/day and 50 mg/week from a double blind, multi-centre, placebo-controlled, 2 yr investigation of OA knee patients in North America. Using fluoroscopic semi-flexed standard radiography, baseline and exit knee radiographs were digitized by laser scanner. Following computerized measurement of minimum medial compartment joint space width, each group was subdivided into joint space narrowing (JSN) non-progressor or JSN-progressor (JSN >or=0.6 mm measured at any point post-baseline). Computerized method of fractal signature analysis (FSA) quantified longitudinal changes separately in horizontal and vertical trabeculae in region of interest (three-fourth width of tibial compartment x 6 mm height) in the medial compartment. Following the initial study, all JSN-progressor knees within the entire patient cohort (N = 1232) were similarly analysed. RESULTS: OA knees in JSN non-progressor group had a slight decrease in FSA for vertical and horizontal trabeculae and showed no drug effect. In JSN-progressor knees, bone loss was greater in both placebo and RIS 5 mg/day groups compared with those in RIS 15 mg/day group in which trabeculae were retained, and in the RIS 50 mg/week group in which the vertical trabecular number increased significantly (P < 0.05). CONCLUSION: This preliminary study showed that patients with marked cartilage loss (JSN>or=0.6 mm) receiving RIS 15 mg/day retained vertical trabecular structure, and those receiving RIS 50 mg/week increased vertical trabecular number, thereby preserving the structural integrity of subchondral bone in knee OA.

Adult↗

PubMed2005

Cancellous bone changes in hip osteoarthritis: a short-term longitudinal study using fractal signature analysis.

OBJECTIVE: To quantify changes to the trabecular structure in the femoral heads of patients with hip osteoarthritis (OA). METHODS: Patients with OA (n=14; F=7), mean (standard deviation age) 50.6 (10.1) years, had macroradiographs at approximately x4 magnification at baseline and 18 months later using a standardized protocol. Following digitization, computerized measurement was obtained of minimum hip joint space width and fractal signature analysis (FSA) measured longitudinal changes separately in the principal compressive (vertical) and horizontal trabeculae at the region of interest within the centre of the head. RESULTS: The patient group had mean annual rate of joint space narrowing of 0.14+/-0.36 mm/yr. FSA detected no significant changes in horizontal trabeculae, whereas the larger principal compressive (vertical) trabeculae (0.96 mm to 1.02 mm) increased significantly in thickness and the fine to medium trabeculae (0.18 mm to 0.54 mm) decreased significantly in number. CONCLUSION: The increased thickness of the larger trabeculae within the compressive structural element of the femoral head is a response to the increase in stress associated with an overall loss of trabeculae in this region, suggesting the presence of an osteoporosis within the femoral head in OA patients.

Female↗

PubMed2005

Relationships between tibial rim alignment and joint space width measurement reproducibility in non-fluoroscopic radiographs of osteoarthritic knees.

RATIONALE: Superimposition of the rims of the medial tibial plateau to within 1mm is an aim of fluoroscopic knee positioning protocols for osteoarthritic (OA) knee radiography and has also been proposed as a measure of quality for non-fluoroscopic methods. OBJECTIVE: To evaluate the effect of tibial rim alignment (TRA) on reproducibility of joint space width (JSW) measurement, both were measured from radiographs taken with each tibial plateau at a range of angles determined by different non-fluoroscopic views. METHODS: TRA and JSW measurements were taken from both knees of 100 OA patients each radiographed in fully extended, schuss/tunnel, and MTP views. Degree of TRA was compared with JSW reproducibility using correlation, and between groups defined both by the 1mm threshold and by TRA-defined quartiles. RESULTS: JSW reproducibility was dependent on the degree of TRA in the fully extended and schuss/tunnel flexed knee views, although the use of the specific TRA threshold of 1mm was not supported. In the MTP view, JSW measurement was found to be highly reproducible across the full range of TRA values. CONCLUSION: These results contradict claims that TRA to within 1mm is essential for useful measurement of JSW. It is an arbitrary threshold, of use in quality control (QC) for protocols which explicitly require such alignment, and the choice of QC criteria for other protocols should be evaluated on a view-by-view basis. The results confirm previous studies showing the MTP view to afford highly reproducible JSW measurement.

Aged↗

PubMed2005

Crystallization and preliminary X-ray crystallographic studies of the mesophilic xylanase A from Bacillus subtilis 1A1.

Xylanases have been the focus of research owing to their industrial potential in animal feed production, food processing and pulp and paper processes. In order to obtain insight into the structural stability of family 11 xylanases, the mesophilic family 11 xylanase (beta-1,4-xylan xylanohydrolase; EC 3.2.1.8) from Bacillus subtilis 1A1 has been crystallized and diffraction data have been collected to 1.7 A. The crystals belong to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 50.93, b = 70.50, c = 40.05 A. The structure has been determined by molecular replacement, resulting in a crystallographic residual of 36.4% after rigid-body refinement.

Bacillus subtilis↗

PubMed2005

A predominant role for hydrogen bonding in the stability of the homodimer of bothropstoxin-I, A lysine 49-phospholipase A2.

Bothropstoxin-I (BthTx-I) is a homodimeric Lys49-phospholipase A(2) isolated from Bothrops jararacussu venom which damages liposome membranes via a Ca(2+)-independent mechanism. The Glu12/Trp77/Lys80 triad at the dimer interface forms extensive intermolecular hydrogen bonds and hydrophobic contacts, and equilibrium chemical denaturation was used to evaluate the effect on homodimer stability of site-directed mutagenesis of these residues. Changes in the intrinsic fluorescence anisotropy and farUV circular dichroism signals were analyzed using a two-step unfolding model of the BthTx-I dimer to estimate the Gibbs free energy changes of transitions between the dimer and native monomer and between the native and denatured monomers. Whereas the Trp77His, Trp77Gln and Glu12Gln mutants showed native-like dimer stabilities, the Trp77Phe, Lys80Met and Lys80Gly mutants showed significantly reduced K(d) values. A reduced dimer stability is correlated with a decrease in the Ca(2+)-independent membrane damaging activity as monitored by the release of a liposome entrapped fluorescent marker. Although the membrane damaging activity of the monomer is fivefold less than the dimer, the myotoxic activity was unaffected, indicating that these two effects are not correlated. These data suggest that the BthTx-I dimer is predominantly stabilized by hydrogen bonding interactions, and highlight the importance of the homodimeric form for efficient Ca(2+)-independent membrane damage.

Amino Acid Sequence↗

PubMed2005

Penetration of ammonium perfluorooctanoate through rat and human skin in vitro.

Rat and human epidermal membranes were mounted onto in vitro diffusion cells with an exposure area of 0.64 cm2, and skin integrity was confirmed using electrical impedance. Following membrane selection, Fluorad FC-118, a 20% aqueous solution of ammonium perfluorooctanoate (AFPO), was applied to the epidermal surface of each skin replicate at approximately 150 microL/cm2 and the donor chamber opening occluded with Parafilm. Serial receptor fluid samples were collected hourly from 1 to 6 h and at 12, 24, 30, and 48 h and analyzed by liquid chromatography-mass spectrometry (LC-MS) for APFO anion (PFO-). For rat skin, the time to steady-state penetration (6500+/-3000 ng APFO x cm(-2) x h(-1)) occurred in less than 12 h, which was sustained until termination (48 h). Based on the concentration of the applied test material, the permeability coefficient (Kp) for APFO in rat skin was calculated to be 3.25+/-1.51 x 10(-5) cm/h. By end of the 48-h exposure period, only a small portion of the total APFO applied (1.44+/-1.13%) had penetrated through rat skin. For human skin, steady-state penetration of APFO (190+/-57 ng APFO x cm(-2) x h(-1)) was reached by 12 h. Based on the concentration of the applied test material, the permeability coefficient for APFO in human skin was calculated to be 9.49+/-2.86 x 10(-7) cm/h. By the end of the 48-h exposure period, only a negligible amount of the total APFO applied (0.048+/-0.01%) had penetrated through human skin. Thus, under infinite dose and occlusive conditions, the steady-state penetration of APFO from a 20% solution was approximately 34-fold faster through rat skin than human skin.

Animals↗

PubMed2004

Effect of crotapotin on the biological activity of Asp49 and Lys49 phospholipases A(2) from Bothrops snake venoms.

Myonecrosis, in addition to edema and other biological manifestations, are conspicuous effects of Bothrops snake venoms, some of them caused by phospholipases A(2) (PLA(2)s). Asp49-PLA(2)s are catalytically active, whereas Lys49-PLA(2)s, although highly toxic, have little or no enzymatic activity upon artificial substrates, due to a substitution of lysine for aspartic acid at position 49. Crotapotin (CA), the acidic counterpart of crotoxin PLA(2) (CB), is a PLA(2)-like protein from Crotalus durissus terrificus snake venom, and is considered a chaperone protein for CB, able to increase its lethality about ten fold, but to inhibit the formation of the rat paw edema induced by carrageenin and by snake venoms. In this study, we demonstrate that CA significantly inhibits the edema induced by BthTX-I (23% inhibition), BthTX-II (27%), PrTX-I (25%), PrTX-III (35%) and MjTX-II (10%) on the mouse paw. CK levels evoked by isolated Asp49 or Lys49-PLA(2)s were reduced by 40% to 54% in the presence of CA and, in all cases, the membrane damaging activity of the toxins was also reduced. Circular dichroism spectra of the PLA(2)s in the presence and absence of CA showed that there was not any detectable secondary structural modification due to association between CA and the myotoxins. However, Fourier Transformed Infrared (FT-IR) analysis indicated that ionic and hydrophobic contacts contributed to stabilize this interaction.

Animals↗

PubMed2004

Multi-species assessment of electrical resistance as a skin integrity marker for in vitro percutaneous absorption studies.

Assessment of percutaneous absorption in vitro provides key information when predicting dermal absorption in vivo. Confirmation of skin membrane integrity is an essential component of the in vitro method, as described in test guideline OECD 428. Historically, assessment of the membrane's permeability to tritiated water (T2O) and the generation of a permeability coefficient (Kp) were used to confirm that the skin membrane was intact prior to application of the test penetrant. Measuring electrical resistance (ER) across the membrane is a simpler, quicker, safer and more cost effective method. To investigate the robustness of the ER integrity measure, the Kp values for T2O for a range of human and animal skin membranes were compared with corresponding ER data. Overall, for human, rat, pig, mouse, rabbit and guinea pig skin, the ER data gave a good inverse association with the corresponding Kp values; the higher the Kp the lower the ER values. In addition, the distribution across a large dataset for individual skin samples was similar for Kp and ER, allowing a cut-off value for ER to be established for each skin type. Based on CTL's (Syngenta Central Toxicology Laboratory) standard static diffusion cells and databridge, we propose that intact skin should have an ER equal to or above (in kOmega): human (10), mouse (5) guinea pig (5), pig (4) rat (3), and rabbit (0.8). We conclude that measurement of ER across in vitro skin membranes provides a robust measurement of skin barrier integrity and is an appropriate alternative to Kp for T2O in order to identify intact membranes that have acceptable permeability characteristics for in vitro percutaneous absorption studies.

Administration, Topical↗

PubMed2004

G protein-coupled receptor fusion proteins in drug discovery.

A wide range of peptides and polypeptides can be appended to either the N- or C-terminus of G protein-coupled receptors without disrupting substantially ligand binding and signal transduction. Following fusion of fluorescent proteins, reporter gene constructs or G protein alpha subunits to the C-terminal tail of a receptor high content and G protein activation assays can be employed to identify agonist ligands. Further modification of the receptor fusions to introduce enhanced levels of constitutive activity and to physically destabilise the protein allows antagonist/inverse agonists screens to be developed in parallel. Equivalent C-terminal addition of pairs of complementary, non-functional, polypeptide fragments allows the application of enzyme complementation techniques. Introduction of N-terminal tags to receptors has also allowed the introduction of novel assay techniques based on a pH-sensitive cyanine dye. These have the capacity to overcome certain limitations of GPCR-fluorescent protein fusions.

Animals↗

PubMed2003

Women and alcohol susceptibility: could differences in alcohol metabolism predispose women to alcohol-related diseases?

These present studies have identified some important differences between male and female subjects in ethanol pharmacokinetics. The development of alcohol misuse in female subjects clearly altered the rate of ethanol elimination as well as increasing the circulating levels of blood acetaldehyde. The identification of an increased level of acetaldehyde in subjects homogenous for ADH(3)(2) genotype, may in part contribute to the higher incidence of alcohol-related damage, i.e. liver cirrhosis, associated with this ADH(3) genotype. The enhanced presystemic alcohol metabolism identified in female Caucasian controls, but not female alcohol misusers, may be an important factor in removing a significant quantity of ethanol during its first pass through the liver and thereby reduce circulating acetaldehyde concentrations.

Acetaldehyde↗

PubMed2003

Comparison of injectable iron complexes in their ability to iron load tissues and to induce oxidative stress.

Iron and copper homeostasis have been studied in various tissues after iron-loading with the polynuclear ferric hydroxide carbohydrate complexes, iron dextran, iron polymaltose, iron sucrose and iron gluconate for four weeks. There were significant increases in the iron content of the different rat tissues compared to controls, with the exception of the brain, which showed no change in its iron content following iron loading. However, the level of iron loading in the different tissues varied according to the preparation administered and only iron dextran was able to significantly increase the iron content of both broncho-alveolar macrophages and heart. The hepatic copper content decreased with iron loading, although this did not reach significance. However the copper content did not alter in the iron loaded broncho-alveolar macrophages. Despite such increases in hepatic iron content, there was little evidence of changes in oxidative stress, the activities of cytosolic (apart from iron dextran) or mitochondrial hepatic superoxide dismutase, SOD, were similar to that of the control rats, confirming the fact that the low reduction potential of these compounds prevents the reduction of the ferric moiety. It was not necessary for macrophages to significantly increase their iron content to initiate changes in NO* release. Iron gluconate and iron sucrose increased NO* release, while iron polymaltose and iron dextran decreased NO* release although only the latter iron preparation significantly increased their iron content. It may be that the speciation of iron within the macrophage is an important determinant in changes in NO* release after ex vivo stimulation. We conclude that tissues loaded with iron by such polynuclear iron complexes have variable loading despite the comparable iron dose. However, there was little evidence for participation of the accumulated iron in free radical reactions although there was some evidence for alteration in immune function of broncho-alveolar macrophages.

Animals↗

PubMed2003

Glasgow's community care programme: 10 year follow up of discharged patients with schizophrenia.

In 1986, the rehabilitation of every long stay psychiatric patient in Glasgow was assessed with a view to reducing bed numbers and developing comprehensive community services. Ten years on, we have attempted to trace 91 patients with a diagnosis of schizophrenia assessed at Gartnavel Hospital, in order to repeat assessments of their psychopathology and levels of functioning. We believe this population represents a unique group in terms of their age, length of hospital stay and chronicity of symptoms. Only two patients were untraced but 36% of the original 91 patients were decreased. Discharge to the community and variations in standards of care appeared to have little impact on the symptomatic presentation of the survivors over ten years. The results provide useful information on the success or otherwise of a large scale discharge and community care programme which is continuing in Scotland.

Aged↗

PubMed2002

The use of taurine analogues to investigate taurine functions and their potential therapeutic applications.

Despite the multitude of evidence for the beneficial effects of taurine supplementation in a variety of disease, the underlying modifying action of taurine with respect to either molecular or biochemical mechanisms is almost totally unknown. We have assessed the development of taurine analogues, particularly where there has been substitution at the suphonate or amine group. Such substitutions allow the investigator to probe the relationship between structure and function of the taurine molecule. In addition such studies should help to ascertain taurine's point of interaction with the effector molecule. These results will prepare the way for the development of the second generation of taurine analogues.

Animals↗

PubMed2002

The influence of iron homoeostasis on macrophage function.

Iron loading of alveolar macrophages in vivo significantly altered their ability to respond to various inflammatory stimuli. This was exemplified by reduced synthesis of inducible nitric oxide synthase after stimulus with lipopolysaccharide and interferon gamma, and an enhanced activation of nuclear factor kappa B in the absence of tumour necrosis factor alpha stimulation, and enhanced production of reactive oxygen species after activation with activated zymosan and PMA. Such results may indicate an imbalance in the production of reactive oxygen and reactive nitrogen species generated by the iron-loaded macrophages after an appropriate stimulus.

Animals↗

PubMed2002

European Community Respiratory Health Survey calibration project of dosimeter driving pressures.

Two potential sources of systematic variation in output from Mefar dosimeters, the system used in the European Community Respiratory Health Survey (ECRHS) study have been evaluated: individual nebulizer characteristics and dosimeter driving pressure. Output variation from 366 new nebulizers produced in two batches for the second ECRHS were evaluated, using a solute tracer method, at a fixed driving pressure. The relationship between dosimeter driving pressure was then characterized and between-centre variation in dosimeter driving pressure was evaluated in an Internet-based survey. A systematic difference between nebulizers manufactured in the two batches was identified. Batch one had a mean+/-SD output of 7.0+/-0.8 mg x s(-1) and batch two, 6.3+/-0.7 mg x s(-1) (p<0.005). There was a wide range of driving pressures generated by Mefar dosimeters as set, ranging between 70-245 kPa, with most outside the quoted manufacturer's specification of 180+/-5%. Nebulizer output was confirmed as linearly related to dosimeter driving pressure (coefficient of determination (R2)=0.99, output=0.0377 x driving pressure-0.4151). The range in driving pressures observed was estimated as consistent with a variation of about one doubling in the provocative dose causing a 20% fall in forced expiratory volume in one second. Systematic variation has been identified that constitutes potentially significant confounders for between-centre comparisons of airway responsiveness in the European Community Respiratory Health Survey, with the dosimeter driving pressure representing the most serious issue. This work confirms the need for appropriate quality control of both nebulizer output and dosimeter driving pressure, in laboratories undertaking field measurements of airway responsiveness. In particular, appropriate data on driving pressures need to be collected and factored into between-centre comparisons. Comprehensive collection of such data to optimize quality control is practicable and has been instigated by the organizing committee for the European Community Respiratory Health Survey II.

Aerosols↗