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Biomedical subjects

P Brooks

Publications and source records attributed to P Brooks.

At least 37 records · Page 2Linked to original sources
PubMed2001

Peripheral blood stem cell transplantation for rheumatoid arthritis--Australian experience.

Trials of high dose immunosuppression and peripheral blood stem cell transplantation (PBSCT) in patients with severe rheumatoid arthritis (RA) have now commenced based on encouraging data from case reports of patients with coexistent malignancy and animal transplant models. Early case reports in Australia documented the potential for cure of RA in most patients receiving allogeneic or syngeneic transplants. However, the relatively high morbidity and mortality of these procedures has necessitated the use of autologous PBSCT. in accordance with international guidelines released by the EBMT/EULAR working party. Phase I trials in autologous PBSCT have seen substantial remissions of RA in the majority of patients who had previously failed all available therapies. Recurrence of disease occurs in most patients usually within 2 years; however, the use of disease modifying agents after recurrence results in substantial amelioration of the disease, again suggesting a form of "immunomodulation." This observation raises the possibility of maintenance therapy associated with procedure to prolong responses. Other modifications of the procedure are discussed, including T cell depletion of the graft, currently the subject of a randomized trial.

Antigens, CD34↗
PubMed2000

Association of immunoproteasomes with the endoplasmic reticulum.

Proteasomes are complex multisubunit proteases which play a critical role in intracellular proteolysis. Immunoproteasomes, which contain three gamma-interferon-inducible subunits, are a subset of proteasomes which have a specialized function in antigen processing for presentation by the MHC class I pathway. Two of the gamma-interferon inducible subunits, LMP2 and LMP7, are encoded within the MHC class II region adjacent to the two TAP (transporter associated with antigen presentation) genes. We have investigated the localization of immunoproteasomes using monoclonal antibodies to LMP2 and LMP7. Immunoproteasomes were strongly enriched around the endoplasmic reticulum as judged by double-immunofluorescence experiments with anti-calreticulin antibodies, but were also present in the nucleus and throughout the cytosol. In contrast, proteasome subunit C2, which is present in all proteasomes, was found to be evenly distributed throughout the cytoplasm and in the nucleus, as was the delta subunit, which is replaced by LMP2 in immunoproteasomes. gamma-Interferon increased the level of immunoproteasomes, but had no effect on their distribution. Our results provide the first direct evidence that immunoproteasomes are strongly enriched at the endoplasmic reticulum, where they may be located close to the TAP transporter to provide efficient transport of peptides into the lumen of the endoplasmic recticulum for association with MHC class I molecules.

Antibodies, Monoclonal↗
PubMed2000

The effect of antigen presenting cells on the cytokine profiles of stable and reactional lepromatous leprosy patients.

In view of varied reports on the Th1/Th2 paradigm in leprosy, we used a novel real time (RT) fluorogenic reverse transcriptase based PCR (RT-PCR) to measure cytokine expression in peripheral blood cells from lepromatous leprosy patients with stable disease and those suffering from erythema nodosum leprosum (ENL/Type II) reactions. To evaluate the role of accessory cells in Th cell differentiation, co-expression of Th cytokines interferon gamma (IFNgamma) and interleukin (IL) 4 and regulatory cytokines IL 10 and IL 12 was compared in antigen stimulated peripheral blood mononuclear cells (PBMC), cultures containing T cells reconstituted with autologous monocytes (MO) and cultures containing T cells reconstituted with autologous dendritic cells (DC). 7/8 stable lepromatous leprosy patients showed co-expression of both IFNgamma and IL 4, suggesting a Th0 or a combination of Th1 + Th2 subsets in PBMC. The RT-PCR demonstrated that stable lepromatous patients and patients in ENL had significantly higher levels of IFNgamma mRNA molecules compared to IL 4. In fact, 5/8 ENL patients had undetectable levels of IL 4 mRNA, with a skewing of the cytokine response towards a Th1-like profile. Consistent with this. IL 12p40 mRNA molecules were significantly higher in the PBMC of ENL patients compared to stable lepromatous patients (P < 0.01). Reconstitution of purified T cells with autologous DC and MO from the stable lepromatous group resulted in down regulation of IL 4 (P < 0.03 for DC and P < 0.02 for MO) and IL 10 (P < 0. 01 for DC and P < 0.02 for MO), and a consequent skewing towards a Th1 profile similar to that seen in ENL patients. The fact that accessory cells could alter the cytokine profile in the reconstituted cultures suggests that they may play a role in determining Th subset differentiation in chronic diseases, and may influence the immunological stability of such diseases.

Antigen-Presenting Cells↗
PubMed2000

Unresolved issues in the role of cyclooxygenase-2 in normal physiologic processes and disease.

Originally suggested to function mainly in inflammatory situations, recent data have implied important roles for the cyclooxygenase-2 isoenzyme in reproductive biologic processes, renal and neurologic function, and the antithrombotic activities of endothelial cells. As cyclooxygenase-2-specific inhibitors have recently become available as analgesic and anti-inflammatory drugs, a comprehensive view of this rapidly evolving field is necessary to anticipate both the potential therapeutic benefits and toxic effects associated with these agents.

Animals↗
PubMed2000

Subcellular localization of proteasomes and their regulatory complexes in mammalian cells.

Proteasomes can exist in several different molecular forms in mammalian cells. The core 20S proteasome, containing the proteolytic sites, binds regulatory complexes at the ends of its cylindrical structure. Together with two 19S ATPase regulatory complexes it forms the 26S proteasome, which is involved in ubiquitin-dependent proteolysis. The 20S proteasome can also bind 11S regulatory complexes (REG, PA28) which play a role in antigen processing, as do the three variable gamma-interferon-inducible catalytic beta-subunits (e.g. LMP7). In the present study, we have investigated the subcellular distribution of the different forms of proteasomes using subunit specific antibodies. Both 20S proteasomes and their 19S regulatory complexes are found in nuclear, cytosolic and microsomal preparations isolated from rat liver. LMP7 was enriched approximately two-fold compared with core alpha-type proteasome subunits in the microsomal preparations. 20S proteasomes were more abundant than 26S proteasomes, both in liver and cultured cell lines. Interestingly, some significant differences were observed in the distribution of different subunits of the 19S regulatory complexes. S12, and to a lesser extent p45, were found to be relatively enriched in nuclear fractions from rat liver, and immunofluorescent labelling of cultured cells with anti-p45 antibodies showed stronger labelling in the nucleus than in the cytoplasm. The REG was found to be localized predominantly in the cytoplasm. Three- to six-fold increases in the level of REG were observed following gamma-interferon treatment of cultured cells but gamma-interferon had no obvious effect on its subcellular distribution. These results demonstrate that different regulatory complexes and subpopulations of proteasomes have different distributions within mammalian cells and, therefore, that the distribution is more complex than has been reported for yeast proteasomes.

Adenosine Triphosphate↗
PubMed2000

Interventions for psoriatic arthritis.

OBJECTIVES: To assess the effects of salazopyrin, auranofin, etretinate, fumaric acid, IMI gold, azathioprine, and methotrexate, in psoriatic arthritis. SEARCH STRATEGY: We searched Medline up to 1995, and Excerpta Medica (June 1974-95). Search terms were psoriasis, arthritis, therapy and/or controlled trial. This was supplemented by manually searching bibliographies of previously published reviews, conference proceedings and contacting drug companies. All languages were included in the initial search. SELECTION CRITERIA: All randomized trials comparing salazopyrin, auranofin, etretinate, fumaric acid, IMI gold, azathioprine, and methotrexate, in psoriatic arthritis. The main outcome measures included individual component variables derived from Outcome Measures in Rheumatology Clinical Trials (OMERACT). These include Acute Phase Reactants, Disability, Pain, Patient Global Assessment, Physician Global Assessment, Swollen joint count, Tender joint count and radiographic changes of joints in any trial of 1 year or longer [Tugwell 1993], and the change in pooled disease index. Only English trials were included in the review. DATA COLLECTION AND ANALYSIS: Data were independently extracted from the published reports by two of the reviewers. An independent blinded quality assessment was also performed. MAIN RESULTS: Nineteen randomized trials were identified of which eleven were included in the quantitative analysis with data from 777 subjects. Although all agents were better than placebo, parenteral high dose methotrexate (not included), salazopyrin, azathioprine and etretinate were the agents that achieved statistical significance in a global index of disease activity (although it should be noted that only one component variable was available for azathioprine and only one trial was available for etretinate suggesting some caution is necessary in interpreting these results). Analysis of response in individual disease activity markers was more variable with considerable differences between different medications and responses. In all trials the placebo group improved over baseline (pooled improvement 0.43 DI units, 95% CI 0. 28-0.59). There was insufficient data to examine toxicity. REVIEWER'S CONCLUSIONS: Parenteral high dose methotrexate and salazopyrin are the only two agents with well demonstrated published efficacy in psoriatic arthritis. The magnitude of the effect seen with azathioprine, etretinate, oral low dose methotrexate and perhaps colchicine suggests that they may be effective but that further multicentre clinical trials are required to establish their efficacy. Furthermore, the magnitude of the improvement observed in the placebo group strongly suggests that uncontrolled trials should not be used to guide management decisions in this condition.

Antirheumatic Agents↗
PubMed2000

Basic biology and clinical application of specific cyclooxygenase-2 inhibitors.

In summary, COX-2 is a highly regulated gene product that catalyzes the local production of PGs in pathologic and physiologic situations (Figure 1). It is clear that COX-2 is the isoform responsible for production of the PGs that mediate inflammation, pain, and fever. However, the role for COX-2 in normal physiology is still being defined. Specific COX-2 inhibitors represent a significant conceptual advance in therapy for patients with arthritis. Although there is no expectation of superior efficacy, clinical trials suggest that efficacy will be comparable with that of nonselective NSAIDs. Clinical trials demonstrate the potential for clinically meaningful reductions in the incidence of the most serious GI complications found with nonselective NSAIDs, i.e., ulcer, perforation, and GI bleeding. Over the next several years, treatment of large numbers of patients with specific COX-2 inhibitors will help to define the biology of COX-2. The magnitude of this advance in the therapy of rheumatic diseases is yet to be accurately determined, but the development of specific COX-2 inhibitors may afford significant new treatment options for many patients.

Cyclooxygenase 2↗
PubMed2000

Factors affecting young children's use of pronouns as referring expressions.

Most studies of children's use of pronouns have focused either on the morphology of personal pronouns or on the anaphoric use of pronouns by older children. The current two studies investigated factors affecting children's choice of pronouns as referring expressions-in contrast with their use of full nouns and null references. In the first study it was found that 2.5- and 3.5-year-old children did not use pronouns differentially whether the adult (a) modeled a pronoun or a noun for the target object or (b) did or did not witness the target event (although there was evidence that they did notice and take account of the adult's witnessing in other ways). In the second study it was found that children of this same age (a) do not use pronouns to avoid unfamiliar or difficult nouns but (b) do use pronouns differently depending on the immediately preceding discourse of the experimenter (whether they were asked a specific question such as "What did X do?" or a general question such as "What happened?"). In the case of specific questions, children prefer to use a null reference but use some pronouns as well (almost never using full nouns); in the case of the generic questions, children use pronouns even more often (and use nouns more as well). This finding was corroborated by some new analyses of children's use of pronouns in specific discourse situations in previously published studies. These findings suggest that children's choice of pronouns as referring expressions in early language development is influenced more by the immediately preceding discourse than other kinds of factors.

Child Language↗
PubMed2000

Non-steroidal anti-inflammatory drug toxicity in the upper gastrointestinal tract.

Non-steroidal anti-inflammatory drug (NSAID) toxicity in the upper gastrointestinal tract is the most common serious drug-induced toxicity reported to drug regulatory authorities. In the last two decades, the rediscovery of H. pylori, development of potent ulcer-healing drugs and specific Cox-II inhibitors have opened new horizons in the management of NSAID toxicity. A Working Party composed of gastroenterologists and rheumatologists in the Asia-Pacific region met in Cairns, Australia, in 1999 to review the literature and develop appropriate guidelines. Recommendations were made based on the latest existing evidence. The importance of clinical events as study endpoints was emphasized. While differences exist between NSAIDs and aspirin, most studies have shown that advanced age, history of peptic ulcer disease, serious concomitant illnesses and coprescription of NSAID/aspirin with anticoagulants and steroids are high risk factors. These patients should be considered for prophylactic anti-ulcer therapy. Helicobacter pylori infection may aggravate the toxicity of NSAIDs and, in selected cases, should be treated before NSAID/aspirin is prescribed. Proton pump inhibitors and misoprostol are the most promising agents in preventing gastric and duodenal ulcers. When NSAID/aspirin needs to be continued in patients who develop an NSAID-related ulcer, proton pump inhibitors offer the best healing effect. With the discovery of cyclo-oxygenase isoforms (Cox-I and Cox-II), preferential and specific Cox-II inhibitors have been developed. While early clinical data have suggested promising antiinflammatory effects and improved safety profile in the gastrointestinal tract, several key issues on long-term safety remain unresolved. The use of potent anti-ulcer therapy, treatment of H. pylori infection and the development of Cox-II inhibitor will change the scenario of NSAID/aspirin-related gastrointestinal toxicity in the next millennium.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

A simple HPLC method for analysing diaminopimelic acid diastereomers in cell walls of Gram-positive bacteria.

A simple and sensitive method for separating and detecting the LL, DD and meso diastereomers of the dibasic amino acid diaminopimelic acid (DAP) in the peptidoglycan of Gram-positive bacteria is described. This method is based on reverse phase HPLC separation of chiral derivatives of DAP followed by fluorescence detection of the o-phthaldehyde derivatives. Its application to the analyses of cell walls of several Gram-positive bacteria is described, where 10 mg or less of dry cells is required.

Cell Wall↗
PubMed2000

Male systemic sclerosis and occupational silica exposure-a population-based study.

BACKGROUND: The continuing uncertainty about the silica-systemic sclerosis relationship led to the investigation of its role as a disease determinant in a large population-based study of systemic sclerosis. AIMS: To compare the frequency, socioeconomic and educational status, age-specific prevalence and duration of occupational silica exposure in males with and without systemic sclerosis. To assess the temporal relationship between exposure and disease onset. To estimate disease latency. To compare disease characteristics between silica-exposed and non-silica-exposed male cases. METHODS: The study was case-control in design. The exposure variable was occupational silica exposure as assessed by an occupational health officer blinded to case/control status and the outcome variable was systemic sclerosis. The employed instrument comprised either a standardised telephone questionnaire (interviewed cases and controls) or medical records (deceased or living-status-unknown cases). RESULTS: Sixty of 160 cases (37.5%) and 11 of 83 (13.3%) controls had occupational silica exposure (OR=3.93; 1.84-8.54). Comparison of data between 64 interviewed cases and all controls demonstrated initial occupational silica exposure occurring before age 40, comparable educational status but significantly different cumulative socioeconomic status with cases being over-represented in semi-skilled and unskilled occupations. Cross-sectional 'current' occupational data underestimated cumulative silica exposure by more than 50%. Silica exposure uniformly preceded onset of second disease symptoms and disease diagnosis. In most, it also preceded onset of first disease symptoms. Disease latency approximated two decades. No disease features distinguished silica-associated systemic sclerosis from idiopathic systemic sclerosis. The duration of silica exposure in the interviewed silica-exposed cases did not significantly exceed that of silica-exposed controls. CONCLUSIONS: Male systemic sclerosis displays socioeconomic dependence. Silica is a disease determinant in male systemic sclerosis, with disease features including a long latency and clinical characteristics indistinguishable from idiopathic disease. Cross-sectional 'current' occupational data underestimate cumulative occupational silica exposure.

Adolescent↗
PubMed2000

Dysregulation of IL-4 expression in lepromatous leprosy patients with and without erythema nodosum leprosum.

In order to increase our understanding of the immunological basis of erythema nodosum leprosum (ENL), we studied Th-like cytokine profiles in 130 leprosy patients, employing both the conventional and a novel, real-time, fluorogenic reverse transcriptase-based PCR (RT-PCR). The concomitant expression of both Th-like cytokines, interferon-gamma and IL-4, and the regulatory cytokines, IL-10 and IL-12, was studied in the peripheral blood cells of leprosy patients with and without ENL. In the conventional RT-PCR, varied cytokine profiles were observed in individual patients of all clinical types. Fifty-three percent of lepromatous patients without ENL and 59% of tuberculoid leprosy patients showed co-expression of IFN gamma and IL-4, indicating a non-polarized Th 0 pattern. Of the 36 patients with ENL, 58% demonstrated a polarized Th 1 pattern, with only 30% expressing both cytokines. Semiquantitative RT-PCR indicated a lower expression of IL-4 compared to that of IFN gamma in the lepromatous patients without ENL; the difference was even greater among those with ENL. The sensitive, real-time PCR confirmed the down-regulation of IL-4 and IL-10, with absence of IL-4 in half of the patients, resulting in skewing of the cytokine response toward a Th 1-like profile.

Cytokines↗
PubMed2000

Following the electronic trail.

How can you protect patient information while maintaining immediate access for qualified employees? HIM professionals across the country are taking leadership roles in developing and managing audit trails for computerized health information. Here are a few of their success stories.

Computer Security↗
PubMed1999

ATP hydrolysis-dependent formation of a dynamic ternary nucleoprotein complex with MutS and MutL.

Functional interactions of Escherichia coli MutS and MutL in mismatch repair are dependent on ATP. In this study, we show that MutS and MutL associate with immobilised DNA in a manner dependent on ATP hydrolysis and with an ATP concentration near the solution K m of the ATPase of MutS. After removal of MutS, MutL and ATP, much of the protein in this ternary complex is not stably associated, with MutL leaving the complex more rapidly than MutS. The rapid dissociation reveals a dynamic interaction with concurrent rapid association and dissociation of proteins from the DNA. Analysis by surface plasmon resonance showed that the DNA interacting with dynamically bound protein was more resistant to nuclease digestion than the DNA in MutS-DNA complexes. Non-hydrolysable analogs of ATP inhibit the formation of this dynamic complex, but permit formation of a second type of ternary complex with MutS and MutL stably bound to the immobilised DNA.

Adenosine Triphosphatases↗
PubMed1999

Autologous haematopoietic stem cell transplants for autoimmune disease--feasibility and transplant-related mortality. Autoimmune Disease and Lymphoma Working Parties of the European Group for Blood and Marrow Transplantation, the European League Against Rheumatism and the International Stem Cell Project for Autoimmune Disease.

This ongoing multicentre prospective phase I/II trial enrolled 74 consecutive patients from 22 centres worldwide with severe autoimmune disease, 35 with rheumatological disorders, 31 with neurological, five with haematological and three with vasculitides. They were treated with autologous peripheral blood or bone marrow transplants according to predetermined criteria. Two patients died after mobilisation before transplant. Seventy-two patients were given 73 transplants, seven bone marrow, and 66 mobilised peripheral blood stem cell transplants. The graft was manipulated to remove T and/or B cells in 43 cases. All 73 transplants engrafted. Five patients died of transplant-related complications: two from bleeding, three from infections. Two patients died of progressive disease. The transplant-related mortality at 1 year of 9% (1-17%; 95% CI) is comparable to the transplant-related mortality of 6% (3-9%; 95% CI) in patients transplanted during the same period in Europe for non-Hodgkin's lymphoma in sensitive relapse (P = 0.39). Sixty patients are evaluable for response, 40 patients (65%) showed some improvement in their disease. Haematopoietic stem cell transplants are feasible for patients with severe refractory autoimmune disease. Transplant-related mortality is comparable to results in patients with non-Hodgkin's lymphoma in responsive relapse. Two-thirds of the patients show at least some response. These preliminary data are promising. Although associated with considerable risk, randomised trials comparing autologous stem cell transplants to conventional therapy are warranted.

Adolescent↗