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Biomedical subjects

M Ryan

Publications and source records attributed to M Ryan.

At least 145 records · Page 8Linked to original sources
PubMed1997

Stress response decreases NF-kappaB nuclear translocation and increases I-kappaBalpha expression in A549 cells.

The stress response and stress proteins confer protection against diverse forms of cellular and tissue injury, including acute lung injury. The stress response can inhibit nonstress protein gene expression, therefore transcriptional inhibition of proinflammatory responses could be a mechanism of protection against acute lung injury. To explore this possibility, we determined the effects of the stress response on nuclear translocation of the transcription factor NF-kappaB, an important regulator of proinflammatory gene expression. In A549 cells induction of the stress response decreased tumor necrosis factor-alpha (TNF-alpha)-mediated NF-kappaB nuclear translocation. TNF-alpha initiates NF-kappaB nuclear translocation by causing dissociation of the inhibitory protein I-kappaBalpha from NF-kappaB and rapid degradation of I-kappaBalpha. Prior induction of the stress response inhibited TNF-alpha-mediated dissociation of I-kappaBalpha from NF-kappaB and subsequent degradation of I-kappaBalpha. Induction of the stress response also increased expression of I-kappaBalpha. We conclude that the stress response affects NFkappaB-mediated gene regulation by two independent mechanisms. The stress response stabilizes I-kappaBalpha and induces expression of I-kappaBalpha. The composite result of these two effects is to decrease NF-kappaB nuclear translocation. We speculate that the protective effect of the stress response against acute lung injury involves a similar effect on the I-kappaB/NF-kappaB pathway.

Adenocarcinoma↗
PubMed1997

Monocyte chemotactic protein-3 (MCP-3)/fibroblast-induced cytokine (FIC) in eosinophilic inflammation of the airways and the inhibitory effects of an anti-MCP-3/FIC antibody.

Monocyte chemotactic protein-3 (MCP-3)/fibroblast-induced cytokine (FIC), a CC chemokine, is chemotactic for cells that typically infiltrate the late-phase allergic reaction. We developed a mouse model of airway inflammation to study the role of MCP-3/FIC. The immunization of mice with OVA resulted in Ag-specific IgE Ab production and the expression of mRNA for IL-4 in the lung tissue. Two weeks after immunization mice were challenged with the allergen by inhalation. Lungs were lavaged, and the tissue was examined at 2 or 24 h. Allergen challenge resulted in the increased recovery of leukocytes in the lavage fluid, but saline challenge did not. There was a significant increase in eosinophils (29 +/- 8% vs 1.2 +/- 0.2%) and lymphocytes (25 +/- 4% vs 5 +/- 2%) in the bronchoaveolar lavage fluid. Histologic examination of the lung demonstrated intense airway inflammation following OVA challenge. The expression of MCP-3/FIC and other CC chemokines (MCP-1, macrophage inflammatory protein-1alpha, and RANTES) was investigated by reverse transcription-PCR followed by densitometric analyses. The allergen challenge up-regulated the expression of mRNA for MCP-1, MCP-3/FIC, and macrophage inflammatory protein-1alpha at 2 and/or 24 h. Immunocytochemical staining for MCP-3/FIC showed that the allergen challenge induced the expression of MCP-3/FIC predominantly in the airway epithelium. Pretreatment of mice with an anti-MCP-3/FIC Ab significantly inhibited the OVA-induced airway inflammation and the bronchoalveolar lavage eosinophilia (8 +/- 2% vs 46 +/- 11% after control Ab, p < 0.03). We conclude that MCP-3/FIC plays a significant role in the allergen-induced eosinophilic inflammation of the airways.

Animals↗
PubMed1997

Saquinavir pharmacokinetics alone and in combination with ritonavir in HIV-infected patients.

OBJECTIVE: The most important hepatic enzyme involved in the metabolism of protease inhibitors is cytochrome P450 3A4 (CYP3A4). Ritonavir (RIT) is a potent inhibitor of CYP3A4 and inhibits saquinavir (SQV) metabolism in healthy volunteers. In this study we investigated the kinetics of SQV when administered alone and in combination with RIT in HIV-infected patients. DESIGN: SQV pharmacokinetics were determined in seven patients who had advanced HIV disease. Steady-state SQV profiles were obtained on two occasions following treatment with SQV 600 mg three times daily alone and when administered with RIT 300 mg twice daily. METHODS: Blood samples were obtained at times 0, 1, 2, 4, 6 and 8 h post-dosing. Following centrifugation, separated plasma was heated at 58 degrees C for at least 30 min to inactivate HIV and stored at -80 degrees C until analysis using high performance liquid chromatography. RESULTS: For patients treated with SQV alone there was a 12-fold variability in the area under the SQV concentration-time curve (AUC0-8h) ranging from 293 to 3446 ng.h/ml. When combined with RIT there was a marked increase in the maximum plasma concentration of SQV [median (range), 146 (57-702) versus 4795 (1420-15810) ng/ml; approximately 95% confidence interval (CI), 2988-6819; P = 0.0006, Mann-Whitney U test]. The AUC0-8h for SQV was also significantly increased in the presence of RIT [median (range), 470 (29-3446) versus 27,458 (7357-108,001) ng.h/ml; approximately 95% CI, 16,628-35,111; P = 0.0006]. CONCLUSIONS: For some patients, administration of SQV 600 mg three times daily results in very low SQV plasma levels and possibly little antiviral effect. Combination of SQV with RIT results in a significant drug interaction mediated by enzyme inhibition which exposes patients to very high SQV concentrations and potential toxicity. If combination therapy with SQV plus RIT is considered then the dose of SQV should be greatly reduced.

Adult↗
PubMed1997

The heat shock response inhibits inducible nitric oxide synthase gene expression by blocking I kappa-B degradation and NF-kappa B nuclear translocation.

We investigated the mechanisms by which the heat shock response inhibits inducible nitric oxide synthase (iNOS) gene expression. Incubation of cultured murine lung epithelium (MLE-15) at temperatures ranging from 39 to 43 degrees C, for 1 h, demonstrated that only severe thermal stress (41 to 43 degrees C) was sufficient to induce the heat shock response. Thermal stress inhibited cytokine-mediated iNOS gene expression only when associated with induction of the heat shock response. Transient transfection assays with an iNOS promoter-reporter gene construct demonstrated that the heat shock response inhibited cytokine-mediated iNOS promoter activity. Electromobility gel shift assays demonstrated that the heat shock response inhibited cytokine-mediated NF-kappa B nuclear translocation. The heat shock response also inhibited cytokine-mediated I kappa-B degradation. These data suggest that the heat shock response inhibits iNOS gene expression by transcriptional mechanisms involving the NF-kappa B/ I kappa-B pathway.

Animals↗
PubMed1997

Determination of pKa values of the histidine side chains of phosphatidylinositol-specific phospholipase C from Bacillus cereus by NMR spectroscopy and site-directed mutagenesis.

Two active site histidine residues have been implicated in the catalysis of phosphatidylinositol-specific phospholipase C (PI-PLC). In this report, we present the first study of the pKa values of histidines of a PI-PLC. All six histidines of Bacillus cereus PI-PLC were studied by 2D NMR spectroscopy and site-directed mutagenesis. The protein was selectively labeled with 13C epsilon 1-histidine. A series of 1H-13C HSQC NMR spectra were acquired over a pH range of 4.0-9.0. Five of the six histidines have been individually substituted with alanine to aid the resonance assignments in the NMR spectra. Overall, the remaining histidines in the mutants show little chemical shift changes in the 1H-13C HSQC spectra, indicating that the alanine substitution has no effect on the tertiary structure of the protein. H32A and H82A mutants are inactive enzymes, while H92A and H61A are fully active, and H81A retains about 15% of the wild-type activity. The active site histidines, His32 and His82, display pKa values of 7.6 and 6.9, respectively. His92 and His227 exhibit pKa values of 5.4 and 6.9. His61 and His81 do not titrate over the pH range studied. These values are consistent with the crystal structure data, which shows that His92 and His227 are on the surface of the protein, whereas His61 and His81 are buried. The pKa value of 6.9 corroborates the hypothesis of His82 acting as a general acid in the catalysis. His32 is essential to enzyme activity, but its putative role as the general base is in question due to its relatively high pKa.

Bacillus cereus↗
PubMed1997

Sports drinks: research asks for reevaluation of current recommendations.

Results of two clinical studies support the use of a carbohydrate-electrolyte beverage to improve performance of intermittent moderate- to high-intensity exercise, such as soccer and ice hockey. Two other studies documented that such beverages improved performance during steady-state moderate- to high-intensity exercise, although the mechanism by which carbohydrate improved performance in these protocols is yet to be determined.

Beverages↗
PubMed1997

Spontaneous regression of granulomatous mycosis fungoides in an HIV positive patient.

The development of mycosis fungoides in HIV-positive patients is uncommon. We describe the granulomatous type of mycosis fungoides in an HIV-positive patient whose cutaneous lesions regressed without treatment. In addition to HIV seropositivity and mycosis fungoides, he had a long history of pulmonary sarcoidosis. Immunophenotyping of the cutaneous lymphoid infiltrates revealed a predominance of CD4+ T cells, and monoclonality was demonstrated by T-cell gene rearrangement studies. The regression of mycosis fungoides in this patient was associated with a falling peripheral blood CD4 T-cell count.

Adult↗
PubMed1997

Using willingness to pay to value alternative models of antenatal care.

Recent years have seen the development of different models of antenatal care, especially for low risk women. More specifically, there has been a move for more general practitioner and midwifery involvement in such care. Given the current changes that are taking place in the provision of antenatal care, it is becoming increasingly important to carry out economic evaluations of alternative models of care. This paper applies the economic instrument of willingness to pay to assess the benefits of two alternative forms of antenatal care: general practitioner/midwife routine led care versus obstetrician led care. The results suggest a willingness to pay of pounds 2500 for antenatal care, with no significant difference between the types of care provided. It is concluded that before firm policy conclusions can be reached, further studies should be undertaken to address methodological issues around the willingness to pay technique.

Adult↗
PubMed1997

Efficacy of the Tibetan treatment for arthritis.

Tibetans in the refugee communities in Northern India are exposed to both traditional Tibetan and Western medicine. For Tibetans suffering from arthritis (or trung-bo), the Tibetan treatment was compared with the Western treatment in an open randomized controlled trial. On a significance level of 0.0005, this trial demonstrated that for these Tibetans, their indigenous treatment worked better than the Western treatment for improved limb mobility.

Arthritis↗
PubMed1997

Generating ideas for teaching mental health nursing.

University teachers who prepare mental health nurses require a variety of teaching techniques to encourage students to engage with the subject matter and to prepare for unknown future problems and dilemmas that they must resolve. Mental health nursing requires the development of specific discipline knowledge, intellectual skills, such as the ability to think laterally and make ethical decisions, and personal attributes, such as maturity and tolerance, as well as practical experience in collaborative care. This article offers a number of strategies that teachers may use in their classes to promote the development of these mental health nursing skills. Other teachers might use these examples to trigger the development of their own repertoire of teaching skills for beginning mental health nurses.

Art↗
PubMed1997

Bordetella pertussis respiratory infection in children is associated with preferential activation of type 1 T helper cells.

The mechanism of protective immunity against Bordetella pertussis generated following recovery from whooping cough in childhood has not yet been elucidated. Studies with a murine respiratory infection model have indicated that cellular immunity, mediated by Th1 cells, plays a role in the clearance of a primary infection with B. pertussis and in protection against subsequent challenge. In the present study, the induction of B. pertussis-specific Th cell subsets in children was examined. Peripheral blood mononuclear cells from B. pertussis-infected or convalescent children proliferated and secreted cytokines following antigen stimulation in vitro. In contrast, responses were weak or undetectable in the majority of children who had not been infected or vaccinated. In all cases, responding T cells produced interferon-gamma but low or undetectable interleukin-5. The findings suggest that Th1 cells may play a role in protective immunity generated following infection with B. pertussis in children.

Aging↗
PubMed1997

Heat shock protein induction protects human respiratory epithelium against nitric oxide-mediated cytotoxicity.

Induction of heat shock proteins (HSPs) confers protection against a variety of cytotoxic agents. We hypothesized that induction of HSPs would protect cultured human respiratory epithelium against nitric oxide (NO)-mediated injury. Incubation of a human bronchial epithelial cell line (BEAS-2B cells) at 43 degrees C for 1.5 h induced expression of several HSPs. Prior induction of HSPs was associated with protection against the NO-donors S-nitroso-N-acetyl penicillamine and 3-morpholinsydnonimine. Protection was evident as improved short term survival and improved ability of cells to recover and proliferate after exposure to NO. Prior induction of HSPs also attenuated NO-mediated decreases in cellular ATP levels, but did not decrease nitrotyrosine formation. Specific overexpression of HSP-70 by plasmid-directed gene transfer protected murine respiratory epithelial cells against S-nitroso-N-acetyl penicillamine. We conclude that in cultured human respiratory epithelium induction of HSPs confers protection against NO-mediated cytotoxicity, possibly by preservation of cellular energetics. We also suggest that HSP-70 may play a specific role in protection.

Adenosine Triphosphate↗
PubMed1997

Selective and transient in vitro effects of heat shock on alveolar type II cell gene expression.

The heat shock response is a highly conserved stress response that can transiently inhibit non-heat shock protein gene expression. Although heat shock protects against acute lung injury, its effects on lung cell gene expression are not known. We studied the in vitro effects of heat shock on the expression of several genes important to alveolar type II cells. Prior induction of heat shock transiently inhibited cytokine-mediated inducible nitric oxide synthase gene expression and cytokine-mediated manganese-superoxide dismutase mRNA expression in murine lung epithelium. In contrast, heat shock had no effect on expression of surfactant protein (SP) A or B mRNA, or SP-B peptide synthesis. Cell survival studies indicated that the inhibitory effects were not secondary to cytotoxicity. Previous heat shock also modestly enhanced the ability of cells to withstand oxidant stress. We conclude that in vitro heat shock has selective and transient inhibitory effects on alveolar type II cell gene expression. Transient inhibition of cytokine-inducible genes, with concomitant conservation of genes required for normal respiratory function (SP) may explain, in part, the mechanism by which heat shock protects during acute lung injury.

Animals↗
PubMed1997

The cost of medicines in the United Kingdom. A survey of general practitioners' opinions and knowledge.

Prescribing costs in general practice continue to grow. Their importance is underlined by the amount of information concerned with costs that general practitioners (GPs) receive, and by the existence of target budgets. In 1986 and 1991, surveys showed that GPs agreed that cost should be borne in mind when choosing medicines, but that their knowledge of drug prices was often inaccurate. This study assessed the current knowledge and attitudes of GPs in the UK in respect of prescribing costs, and examined the influence of various developments in general practice since 1986 on the accuracy of drug price estimation. 1000 randomly selected GP principals (500 in Scotland and 125 in each of 4 English health regions) were sent a postal questionnaire. The GPs' level of agreement with 5 statements concerned with prescribing costs, and the accuracy of their estimates of the basic price of 31 drugs, were analysed. Most GPs (71%) agreed that prescribing costs should be taken into account when deciding on the best treatment for patients. Fundholders were more likely than non-fundholders: (i) to agree that prescribing costs could be reduced without affecting patient care; (ii) to agree that providing more information on costs would lower the cost of prescribing; and (iii) to comment that cost guidelines had changed their prescribing habits. Fundholders were less likely than non-fundholders to reject the principle of fixed limits on prescribing costs. Overall, one-third of the price estimates given were accurate (within 25% of the actual cost). For the most expensive drugs in the survey [those priced over 10 pounds sterling (Pound) per pack], half of the price estimates were accurate. There were significant differences between non-fundholders' and fundholders' estimates of the price of less expensive drugs (those priced at less than 10 pounds per pack). Use of a formulary or computer-displayed drug price information did not affect the accuracy of price estimates. It may be that GPs who were more knowledgeable and concerned about costs were more likely to become fundholders. It is also possible that the expansion of fundholding, or other mechanisms that give GPs responsibility for resource allocation, might improve accurate cost awareness in prescribing. Clinical and economic review of repeat prescribing is recommended.

Cost-Benefit Analysis↗