Biomedical subjects

R O Williams

Publications and source records attributed to R O Williams.

At least 55 records · Page 3Linked to original sources

PubMed1997

Suppression of collagen-induced arthritis by continuous administration of IL-4.

The onset of collagen-induced arthritis in DBA/1 mice is accompanied by a predominantly Th1 response, characterized by production of the proinflammatory cytokines IFN-gamma and TNF-alpha, and a predominance of IgG2a anti-collagen Abs. This study has primarily addressed the effects of continuous administration of exogenous IL-4, a Th2 cytokine, on collagen-induced arthritis in terms of time of onset, clinical symptoms, and histologic changes compared with those in untreated controls. The contributions of Th1 and Th2 cell responses were studied by examining anti-CII IgG subclasses, serum IgE levels, and cytokine production by synovial membrane and lymph node cell cultures. Continuous exposure to IL-4 for 28 days significantly delayed the onset of arthritis from 19 to 37 days and suppressed clinical symptoms. Arthritis occurred approximately 13 to 24 days after treatment ceased. Thereafter, the severity and duration of clinical symptoms were similar to those in control animals, although both joint damage and inflammation at the histologic and cellular levels were less severe than those in untreated controls. During IL-4 treatment, anti-collagen Ab levels were reduced (most significantly those of the IgG2a subclass), histology scores were lower, and the most striking effect was a 1000-fold decrease in TNF-alpha secretion by synovial cells. No significant differences in IgE levels were found between controls and IL-4-treated mice. These data suggest that the anti-inflammatory properties of IL-4 are mediated in part by down-regulation of Th1 responses rather than up-regulation of Th2 responses.

Animals↗

PubMed1997

Determination of diazolidinyl urea in a topical cream by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of diazolidinyl urea (DU) in a cream formulation is described. The aqueous phase of the emulsion was separated by centrifugation, removed, filtered, diluted and applied onto the HPLC system. DU was detected by ultraviolet absorption at a wavelength of 214 nm. The calibration curve was linear over the range of 79-553 micrograms/ml, and identical when determined on consecutive days. The relative standard deviation for repeat determinations was less than 0.5%. Recoveries were 97.74-101.72%. This analytical method is useful for quantitation of DU in cream formulations.

Administration, Topical↗

PubMed1997

Influence of metering chamber volume and water level on the emitted dose of a suspension-based pMDI containing propellant 134a.

PURPOSE: To determine the influence of metering chamber volume of a valve and water content of an aerosol formulation containing propellant 134a on dose delivery through the valve (DDV) and aerodynamic particle size distribution of the emitted dose. METHODS: The drug was admixed with ethanol, sonicated, and metered into cans. Valois DF10 RC valves were crimped onto the cans and propellant 134a was gassed through the valve. The DDV was determined using a dosage sampling tube. Aerodynamic particle size distributions were determined by cascade impaction. The water content was determined by Karl Fisher titration. RESULTS: The DDV increased linearly and the aerodynamic particle size distribution was not influenced as the metering chamber volume of the valve was increased. More drug was emitted from the valve from the initial actuations of the can than from the end. Valves with larger metering chamber volumes demonstrated less variability in DDV than those with smaller metering chamber volumes for the initial actuations. The DDV determined for actuations at the end of the can decreased as water was added extemporaneously. The mass median aerodynamic diameter (MMAD) increased as the water level was increased in the formulation. The geometric standard deviation (GSD) and percent respirable fraction (RF) were not influenced by metering chamber volume or water content. CONCLUSIONS: The valve chosen for the development of pressurized metered dose inhaler (pMDI) formulations with propellant HFA 134a must be investigated to determine the uniformity of drug delivery. The presence of water influences the characteristics of the emitted dose.

Administration, Intranasal↗

PubMed1997

Dynamics of proinflammatory cytokine expression in the joints of mice with collagen-induced arthritis (CIA).

This report contains a description of the cellular localization and kinetics of proinflammatory cytokine expression in murine CIA, a model for rheumatoid arthritis. Tissue cryostat sections of undecalcified paws from type II collagen-immunized DBA/1 mice, taken 1-10 days after the onset of clinical arthritis, were examined for the presence of tumour necrosis factor-alpha (TNF-alpha), IL-1beta and IL-6 using an indirect immunoperoxidase technique. In parallel, interferon-gamma (IFN-gamma) production by lymph node cells, stimulated in vitro with type II collagen, was assessed as a marker of T cell activity. The main areas of TNF-alpha, IL-1beta and IL-6 expression were in the synovial lining layer and in tissue contiguous with cartilage and bone (the marginal zone), in particular at sites of pannus formation and joint erosion. There was a progressive increase in the number of TNF-alpha-, IL-1beta- and IL-6-positive cells from day 1 to day 10 of arthritis, during which time IFN-gamma production by CD4+ T cells from draining lymph nodes declined sharply. A further finding of potential significance was that TNF-alpha was consistently detected at day 1 of arthritis, whereas IL- 1beta-positive cells were not found until day 3, suggesting that the expression of TNF-alpha precedes that of IL-1beta.

Animals↗

PubMed1997

TNF blockade in rheumatoid arthritis: implications for therapy and pathogenesis.

The role of the immune response in rheumatoid arthritis (RA) is a subject of debate, although it is widely believed to be a T-cell-driven disease. Progress is being hindered by lack of convincing evidence of a defined specific antigen initiating or perpetuating the response. Clinical trials using monoclonal antibodies directed against T-cell surface molecules such as CD4. CD5, and CD7 have thus far not provided evidence of efficacy. The negative data may reflect inadequate dosing or could suggest that indiscriminate depletion of T cells is insufficient by itself as a therapeutic strategy. Blocking proinflammatory cytokines (e.g. TNF alpha, IL-1) or augmenting anti-inflammatory cytokines (e.g. IL-10) offers an alternative approach to therapy. Clinical trials using monoclonal anti-TNF alpha have been particularly successful in controlling inflammation and markedly reducing acute phase proteins and cellular ingress. However, because disease invariably relapses, repeated therapy is necessary. Preliminary experience suggests that this is possible. Anti-TNF therapy for RA has defined a molecular target and new approach for treating immuno-inflammatory disorders.

Animals↗

PubMed1997

An in vitro method to investigate food effects on drug release from film-coated beads.

The influence of simulated high-fat meals on drug release from beads coated with modified-release ethylcellulose coating formulations was investigated as a function of plasticizer type and concentration, and coating level. Ethylcellulose-coated beads were soaked in peanut oil prior to testing to simulate the influence of concomitant administration of the dosage form with ingestion of fatty meals. The USP apparatus 3 dissolution procedure was employed to study the drug release properties of the beads. It was found that the ethylcellulose-coated beads plasticized with either triethyl citrate (TEC) or dibutyl sebacate (DBS) had faster drug release rates after the peanut oil treatment. Scanning electron microscopy (SEM) revealed that the peanut oil soak caused the polymeric films to detach from the surface of the bead, producing a series of uneven ridges and cracks in the coating. Modulated differential scanning calorimetry (DSC) demonstrated that the glass transition temperature was increased for DBS-plasticized films soaked in peanut oil, and that it was not influenced for TEC plasticized films. Similar results were found for the puncture strength, percent elongation, and modulus of elasticity for the DBS- and TEC-plasticized films soaked in peanut oil. The results verified that the DBS was solubilized and extracted from the plasticized film during the peanut oil soak, and that the film plasticized with the TEC was not significantly affected by the peanut oil soak. Drug release was influenced by the plasticizer type and concentration, and coating level applied to the beads.

Calorimetry, Differential Scanning↗

PubMed1996

Anti-CD4 monoclonal antibodies suppress murine collagen-induced arthritis only at the time of primary immunisation.

We have examined the ability of a mixture of two anti-CD4 mAbs to protect against collagen-induced arthritis. Anti-CD4 mAbs, administered around the time of primary immunisation with type II collagen in adjuvant, reduced the subsequent incidence of arthritis from 67 to 16% (P < 0.01 by Fisher exact test). However, anti-CD4 treatment 3 weeks after the primary immunisation did not significantly affect the incidence of arthritis. This result extends earlier findings concerning the lack of efficacy of anti-CD4 treatment in established collagen-induced arthritis. Next, the ability of anti-CD4 treatment to induce tolerance to bovine type II collagen (and hence protect against arthritis) was evaluated using a regime known to be capable of inducing tolerance to human gamma-globulin. Anti-CD4 treatment completely failed to induce tolerance to type II collagen, as judged by levels of anti-collagen antibody, or protect against collagen-induced arthritis. These findings highlight the potential limitations of anti-CD4 mAb depleting treatment in immunotherapy.

Animals↗

PubMed1996

Interleukin-10 inhibition of the progression of established collagen-induced arthritis.

OBJECTIVE: Interleukin-10 (IL-10) is a potent inhibitor of the proinflammatory cytokines, including tumor necrosis factor alpha and IL-1, which are considered important in the pathogenesis of rheumatoid arthritis (RA). The study was undertaken to establish whether IL-10 can ameliorate arthritis in the collagen-induced arthritis (CIA) model of RA. METHODS: DBA/1 mice were immunized with bovine type II collagen in adjuvant, and treated daily after disease onset with recombinant murine IL-10 or with saline as a control. Mice were monitored for paw swelling and clinical score. Histologic analysis was also performed. RESULTS: IL-10 treatment of established CIA inhibited paw swelling (P < 0.0001), as well as disease progression as defined by clinical score (P < 0.0002). Cartilage destruction, as assessed histologically, was reduced in IL-10-treated mice compared with controls (P < 0.01). CONCLUSION: IL-10 suppresses established CIA, probably by inhibiting proinflammatory cytokine production. Our results, taken together with previously reported findings, indicate a potential therapeutic role for IL-10 in RA.

Animals↗

PubMed1996

Relationship between Th1/Th2 cytokine patterns and the arthritogenic response in collagen-induced arthritis.

It is hypothesized that the balance of cytokines produced by Th1/Th2 subsets of T helper cells plays an important role in the development of autoimmune diseases. Murine collagen-induced arthritis (CIA) is an example of an autoimmune disease in which immunization with cartilage-derived type II collagen induces, firstly, a T cell response to type II collagen and, secondly, the manifestation of a destructive inflammatory response in affected joints. We have investigated the role of Th1/Th2 responses in the development of CIA by monitoring levels of interferon (IFN)-gamma (a Th1 cytokine) and interleukin (IL)-4 and IL-10 (Th2 cytokines), and IL-1 beta and tumor necrosis factor (TNF) (pro-inflammatory cytokines) produced by cultured draining lymph node cells (LNC) from collagen-immunized DBA/1 mice during the induction phase of arthritis and throughout the time of clinical manifestation and subsequent remission of the disease. Although a transient increase in IL-10 was detected 3 days after immunization, Th2 cytokine production was found to be almost completely suppressed 6 days after immunization. In contrast, IFN-gamma was detected in LNC cultures as early as 6 days after immunization and the addition of type II collagen to the culture medium resulted in an approximately 10-fold increase in IFN-gamma production, indicating that a predominantly Th1 response had become established by this time. IFN-gamma production by LNC was found to be further increased at the time of clinical manifestation of arthritis and could be up-regulated by co-culture with type II collagen. IL-10 was not detected in LNC cultures at the onset of arthritis and IL-4, although present, was found to be markedly suppressed in LNC cultures containing type II collagen. These findings indicate that Th1 responses are predominant at the time of onset of arthritis and that the activation of collagen-specific Th1 cells may result in suppression of Th2 activity. IFN-gamma production declined progressively during the progression and subsequent remission of arthritis whereas levels of IL-10 increased and low, though persistent, levels of IL-4 were detected throughout this period. High levels of IL-1 beta and TNF-alpha production were detected at the onset of the disease. The role of Th1 responses in the development of CIA was further emphasized by the observation that immunization of mice with type II collagen in incomplete Freund's adjuvant, which normally fails to induce arthritis, resulted in a predominantly Th2 cytokine profile.

Animals↗

PubMed1996

Beam flatness perturbation effects of a perforated thermoplastic immobilization device on 6 and 12 MeV electron beams.

PURPOSE: Perforated thermoplastic masks are widely used in radiotherapy of head and neck malignancies. They provide for patient immobilization and increase setup reproducibility. Some oncology treatment centers cut mask portals (windows) for the beam to pass through; for those centers that do not, the mask affects beam fluence. The extent to which beam flatness is altered by such a mask is investigated. MATERIALS AND METHODS: The effects of perforated thermoplastic on 6 MeV and 12 MeV electron beams was described in terms of optical density differences in a comparative film study. RESULTS: Variations of beam flatness were documented of up to 11.8% at 5 mm depth for 6 MeV, and 8.1% for 12 MeV electrons. The depth at which this effect may be considered insignificant (mean optical density differences < 2%) is approximately 10 mm for both beam energies. CONCLUSIONS: For clinical situations where the target volume is superficial, some consideration should be given to beam inhomogeneity caused by the mask.

Humans↗

PubMed1995

TNF alpha is an effective therapeutic target for rheumatoid arthritis.

Rheumatoid arthritis is the most common of a number of diseases in which inflammation and tissue destruction is driven by an autoimmune process. Current therapy is inadequate, and this has prompted major research efforts, both in academia and industry, to understand more about the pathogenesis, and hence provide the rationale for new therapeutic strategies. Here we review our studies of cytokine expression and regulation in rheumatoid joints, which has culminated in demonstrating that TNF alpha blockade, using a chimeric (human IgG1/K, mouse Fv) anti-TNF alpha antibody, cA2, markedly ameliorates arthritis. This defines a therapeutic target for rheumatoid arthritis.

Animals↗

PubMed1995

Development and in vitro-in vivo evaluation of a multiparticulate sustained release formulation of diltiazem.

PURPOSE: To develop and evaluate the in vitro/in vivo performance of diltiazem sustained release pellets that were prepared by the Wurster column process. METHODS: Pellets containing diltiazem were prepared by spraying a slurry of micronized diltiazem hydrochloride, pharmaceutical glaze and alcohol onto an appropriate mesh fraction of nonpareil seeds using the Wurster column. A two-step drug layering process was used to increase drug loading from 60% to 75%. The oven-dried diltiazem basic pellets were coated with ethylcellulose/dibutyl sebacate coating solution to yield diltiazem sustained release pellets. An open, randomized Latin square, three-way crossover clinical study was used to evaluate the in vivo performance of the coated product. RESULTS: Altering the mesh fraction of the starting nonpareil seeds for this layering process was found to affect the release characteristics of drug from the pellets. An oven-drying step was required to stabilize the diltiazem basic pellets. The thicker the drug loading layer the longer the oven drying is needed to stabilize the pellets. The diltiazem sustained release pellets produced by these methods displayed sustained release dissolution profiles both in vitro and in vivo. Diltiazem basic pellets coated with a 0.6% ethylcellulose/dibutyl sebacate coating showed a different rate of absorption (lower Cmax and higher Tmax) and the same extent of absorption as compared to Cardizem tablets. CONCLUSIONS: Clinical data confirmed that this formulation approach is an effective means to produce a diltiazem sustained release product.

Adult↗

PubMed1995

Monoclonal anti-TNF alpha antibody as a probe of pathogenesis and therapy of rheumatoid disease.

Rheumatoid arthritis is a common cause of chronic disability for which current therapies are of limited value in controlling the disease process and outcome. Our initial approach to understanding the pathogenesis of RA and defining a novel therapeutic target was to investigate the role of cytokines by blocking their action with antibodies on cultured synovial-derived mononuclear cells in vitro. These investigations suggested that neutralization of TNF alpha with antibodies significantly inhibited the generation of other pro-inflammatory cytokines also over-produced, such as, IL-1, GM-CSF, IL-6 and IL-8. The implication that blockade of a single cytokine, TNF alpha might have far-reaching effects on multiple cytokines and thereby exert significant anti-inflammatory and protective effects on cartilage and bone of joints, was tested in arthritic DBA/1 mice immunized with collagen II. Impressive amelioration of joint swelling and joint erosions in this model encouraged clinical trials with a monoclonal anti-TNF alpha antibody. The cA2 chimeric anti-TNF alpha high-affinity antibody was initially tested in an open-label study at a dose of 20 mg/kg on 20 patients, with substantial and universal benefit. Subsequently, a randomized placebo-controlled double-blind trial was performed on 73 patients comparing a single intravenous injection of placebo (0.1% human serum albumin) with two doses of cA2. Using a composite disease activity index, at 4 weeks post infusion, 8% of patients receiving placebo improved compared with 44% receiving 1 mg/kg cA/2 and 79% receiving 10 mg/kg. Between 2 to 4 repeated cycles of cA2 were administered to 7 patients and all patients showed improvement of a similar magnitude with each cycle. These data support our proposition that TNF alpha is implicated in the pathogenesis of RA, and is thus a key therapeutic target. Monoclonal anti-TNF alpha antibodies control disease flares and are candidate agents for longer-term control of RA, although repeated therapy with cA2 is associated with anti-idiotypic responses in 50% of patients and a trend toward shortening of the duration of response. In the DBA/1 arthritic mice, synergy of action of anti-TNF and anti-CD4 is observed together with suppression of an anti-globulin response, indicating one way in which benefit might be augmented in the future.

Animals↗

PubMed1995

Successful therapy of collagen-induced arthritis with TNF receptor-IgG fusion protein and combination with anti-CD4.

We have previously shown that anti-tumour necrosis factor (TNF) monoclonal antibody (mAb) ameliorates established collagen-induced arthritis and that the efficacy of this form of treatment can be enhanced by concurrent anti-CD4 treatment. Here we assess the efficacy of a human p55 TNF receptor-IgG fusion protein (p55-sf2), given alone or with anti-CD4 mAb. TNF receptor-IgG fusion protein (100 micrograms) suppressed paw swelling and limb recruitment in established arthritis and reduced the incidence of erosions in the proximal interphalangeal joints from 92% to 50%, which was comparable to 41% erosions using anti-TNF mAb. Methylprednisolone acetate (4.2 mg/kg/week) reduced clinical signs of inflammation in a manner comparable to TNF blockade but had little effect on the incidence of erosions. Co-administration of anti-CD4 and TNF receptor-IgG led to an even greater therapeutic effect than TNF receptor-IgG alone, with the incidence of erosions being reduced from 100% to 17%. Serological analyses showed that the beneficial effects of anti-CD4 and TNF receptor-IgG could be partly explained by the ability of anti-CD4 to prevent a neutralizing antibody response. These results confirm the importance of TNF in destructive inflammatory arthritis and demonstrate the feasibility of therapeutically targeting TNF with a form of TNF receptor. Finally, the findings confirm the beneficial effects of TNF-targeted therapy coupled with anti-CD4 therapy.

Animals↗

PubMed1994

Synergy between anti-CD4 and anti-tumor necrosis factor in the amelioration of established collagen-induced arthritis.

Anti-CD4 treatment is reported to prevent collagen-induced arthritis if administered before the onset of clinical disease but has relatively little effect on established arthritis. In contrast, we have recently shown that anti-tumor necrosis factor alpha/beta (TNF) treatment reduces the severity of established arthritis. We now study the effect of combined administration of anti-CD4 monoclonal antibody (YTS 191.1.2/YTA 3.1.2) and anti-TNF monoclonal antibody (TN3-19.12) in established arthritis. Anti-CD4 treatment caused some reduction in paw-swelling but did not significantly prevent joint erosion. A suboptimal dose of anti-TNF alone had no significant effect on arthritis. In contrast, anti-CD4 plus suboptimal anti-TNF significantly reduced paw-swelling, limb involvement, and joint erosion. As previously reported, an optimal dose of anti-TNF alone inhibited paw-swelling, limb involvement, and joint erosion. However, optimal anti-TNF combined with anti-CD4 caused significantly greater reductions in paw-swelling and joint erosion than those achieved by optimal anti-TNF alone. Coadministration of anti-CD4 was also effective in preventing an antibody response to the hamster anti-TNF antibody, which may have implications for long-term therapy in human disease. Thus anti-CD4 acts synergistically with anti-TNF in ameliorating established collagen-induced arthritis and this combined therapeutic approach may provide effective long-term control of rheumatoid arthritis.

Animals↗

PubMed1994

Sequence and expression of a 90-kilodalton heat-shock protein family member of Theileria parva.

A Theileria parva specific full-length cDNA clone, T7, which encodes a protein with more than 60% homology to heat shock protein 90 (hsp90) of other organisms, has been identified. T7 appears to be a single copy gene. The gene is expressed as a protein of 87 kDa in both the sporozoite and schizont stages of T. parva. The protein was not found in the piroplasm stage, although the corresponding transcript was detected, suggesting post-transcriptional regulation of the gene. In the schizont stage the T7 protein is upregulated upon heat shock and localized in the cytoplasm.

Amino Acid Sequence↗

PubMed1994

High levels of anti-type II collagen IgG in west African patients with rheumatoid arthritis.

OBJECTIVE: To compare levels of antitype II collagen IgG in West African and British patients with rheumatoid arthritis (RA). METHODS: IgG levels to native and denatured type II collagen were measured by ELISA: RESULTS: Serum levels of antinative type II collagen IgG were raised in 17 of 58 (29%) West African patients with RA. In contrast, 14 of 89 (16%) British RA patients had raised levels of antinative type II collagen IgG. Levels of antinative type II collagen IgG were also higher in West African patients with RA than in the British patients. CONCLUSION: Our results suggest that type II collagen autoimmunity plays a more prominent role in RA in West Africa than in Britain.

Africa, Western↗

PubMed1993

The molecular basis of transformation of lymphocytes by Theileria parva infection.

The protozoan intracellular parasites, Theileria parva and Theileria annulata, infect cattle and cause severe and fatal leukocytic proliferative diseases. The proliferation is dependent on the presence of the parasites in the host cell cytoplasm. T. parva-infected cells proliferate permanently in cell culture and exhibit many features characteristic of tumor cells. The proliferation is reversible by treatment with parasite-specific drugs. Constitutive expression of interleukin-2, its receptor and their transcription factor, NF-kappa B, are dependent on the parasite and suggest autocrine growth. Cell-cell contact possibly via T cell adhesion molecules has been shown to stimulate proliferation.

Animals↗