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Biomedical subjects

B Madden

Publications and source records attributed to B Madden.

At least 19 recordsLinked to original sources
PubMed2001

Bacterial endocarditis: a rare complication following orthotopic cardiac transplantation.

We describe a 46-year-old man who developed infective endocarditis, meningitis, sternal abscess, and infective cerebral emboli after cardiac transplantation. Staphylococcus aureus was the infective organism. We successfully managed the patient with flucloxacillin and fusidic acid to treat infection, and with prostacyclin for systemic embolization.

Cyclosporine↗
PubMed2001

Tracheal stenting for rupture of the posterior wall of the trachea following percutaneous tracheostomy.

Perforation of the posterior wall of the trachea during percutaneous tracheostomy is a recognised complication. Treatment by either conservative or surgical management has been described. We report two patients who developed posterior tracheal wall perforation following percutaneous tracheostomy who were successfully treated by insertion of covered, expandable metallic stents. This is a well tolerated procedure that has minimal complications and can be performed at the bedside. We recommend that tracheal stenting should be considered for the management of posterior tracheal wall perforation following percutaneous tracheostomy in those patients unsuitable for surgical intervention.

Aged↗
PubMed1999

Myocyte loss in chronic heart failure.

This study examined whether or not there is progressive loss of individual myocytes in established heart failure, accounting for the progressive left ventricular dysfunction; whether such loss is by necrosis or apoptosis; and whether such loss is more pronounced in ischaemic heart disease or idiopathic dilated cardiomyopathy. Tissue for patients undergoing cardiac transplantation for clinical end-stage heart disease was used. The clinical diagnosis was not known to the observer at the time of analysis. Indices of potential myocyte loss were: detection of apoptotic nuclei in situ, using the TUNEL method, immunohistochemistry for CD120a, CD120b, CD95, perforin and granzyme B; binding of C9 complex; and lipofuscin deposition within macrophages. Interstitial macrophages and T cells and their relationship to myocyte loss were also examined. There is indeed low grade myocyte loss in chronic heart failure, but there was no difference between the disease groups; rather, there was marked patient-to-patient variation within each category. Thus in chronic heart failure myocyte loss does occur, and both necrosis and apoptosis contribute to this loss, irrespective of the underlying nature of the disease. Any mechanism which accounts for myocyte loss must be common to both conditions, rather than specific for a pre-operative diagnosis.

Adult↗
PubMed1998

Regulation and processing of a precursor form of eosinophil granule major basic protein (ProMBP) in differentiating eosinophils.

The cDNA for eosinophil granule major basic protein (MBP) encodes a prepromolecule with a total length of 222 amino acids (preproMBP). PreproMBP includes a secretory leader of 15 amino acids, an acidic propiece of 90 amino acids, and a basic MBP portion of 117 amino acids. The function of the propiece, which has a predicted pI of 3.9, is unknown, but it gives proMBP an overall acidic charge. Because proMBP is not found in mature eosinophils, we analyzed eosinophil differentiation in interleukin-5 (IL-5)-stimulated umbilical cord stem cells cultured for 24 days. By immunofluorescence, proMBP appeared by day 6 and peaked on day 18, whereas MBP was prominent at days 12 to 24. By day 6, Western blots detected heterogeneous glycosylated 33-kD proMBP; its peak expression occurred on day 12. Western blots showed sequential processing of 33-kD proMBP to an 18-kD intermediate form and finally to 14-kD MBP. By dual label immunoelectron microscopy, proMBP was localized primarily to large uncondensed eosinophil granules, whereas MBP was localized to granules containing a condensed central area. Thus, proMBP is likely expressed and processed as the granule condenses in a multistep process to 14-kD MBP in differentiating eosinophils.

Amino Acid Sequence↗
PubMed1998

Synthesis, DNA-cleaving properties and cytotoxicity of intercalating chelidamic acid derivatives.

We have explored the potential antitumour activity of DNA-intercalating free radical generators based on compounds constructed from 9-anilinoacridine and chelidamic acid as an iron (II) binding centre. Here we describe their synthesis, DNA cleaving ability and activity against a panel of human tumour cell lines in culture. We also investigate their potential for use as DNA footprinting agents. Previous work has shown that the parent compound, FTP1, cleaves DNA in an essentially sequence neutral fashion and has modest cytotoxicity [Searcey, M., McClean, S., Madden, B. & Wakelin, L.P.G. (1997) Journal of the Chemical Society. Perkin Transactions, 2, 523]. Here we have equipped the acridine chromophore with an N,N-dimethylaminoethyl-4-carboxamide substituent, giving the threading agent FTP2, which confers selectivity for cleaving in GC-rich sequences, avoidance for binding to AT-tracts and 8-fold enhanced cytotoxicity compared with FTP1. Although this side chain bestows slow dissociation kinetics on DNA complexes of 9-anilinoacridines, it does not enhance the overall cutting efficiency of FTP2, implying that free-radical generation, DNA hydrogen abstraction and sugar fragmentation are fast compared with DNA-ligand complex lifetimes. FTP2 does not appear to be susceptible to resistance by the mdr phenotype in human ovarian carcinoma cells. We also report that FTP2 is an effective footprinting agent for GC-selective binding ligands and that it has some advantages over FTP1 in this regard.

Acridines↗
PubMed1997

Increased ventricular sialylation in patients with heart failure secondary to ischemic heart disease.

BACKGROUND: Elevated serum sialic acids are associated with increased cardiovascular mortality, but sialic acid levels have not been studied in cardiac tissue. METHODS: Myocardial samples were obtained at the time of transplantation from 23 patients (age 54 +/- 12 years) with heart failure secondary to ischemic heart disease and 16 patients (age 51 +/- 7 years) with idiopathic dilated cardiomyopathy (DCM). A control group comprised postmortem samples obtained from 14 patients (age 70 +/- 5 years) who died of non-cardiovascular causes. Ventricular sialylation was quantitated using the sialic acid-specific lectins Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA) using a chemiluminescence assay. Results are expressed as the percentage (+/-standard error of the mean) of the binding of lectin to a standardized control sample of human myocardium. RESULTS: Ventricular sialylation recognized by MAA was 55 +/- 7% in patients with heart failure secondary to ischemic heart disease compared with 26 +/- 7% for DCM (p = 0.006) and 32 +/- 8% for controls (p = 0.04), and that recognized by SNA was 69 +/- 7% in patients with heart failure secondary to ischemic heart disease compared with 42 +/- 6% for DCM (p = 0.006) and 38 +/- 7% for controls (p = 0.006). No significant difference in ventricular sialylation was observed between patients with DCM and controls. CONCLUSION: Myocardial levels of sialic acids are significantly increased in patients with heart failure secondary to ischemic heart disease compared with patients with idiopathic dilated cardiomyopathy and controls. Our findings are important in view of recent reports of an association between serum sialic acid concentration and cardiovascular mortality and require further investigation.

Aged↗
PubMed1997

Defective antigen presentation by lavage cells from terminal patients with cystic fibrosis.

Macrophages separated from lavage samples obtained from lungs removed at transplantation from patients with cystic fibrosis (CF) and other lung diseases, have been compared with circulating monocytes from the same patients for their ability to stimulate allogeneic normal circulating lymphocytes and to present antigen to autologous hilar lymph node cells. In general, macrophages separated from lavage samples from CF patients were unable to stimulate allogeneic lymphocytes and to present antigen, although monocytes from the same patients were functional in both assays. In contrast, lavage cells from non-CF patients were generally effective in both allogeneic stimulation and antigen presentation. These data suggest that immune cells within the lungs of CF patients are functionally compromised, a deficiency which may contribute to the recurrent infections characteristic of the disease.

Antigen Presentation↗
PubMed1995

Identification of a complex between centrin and heat shock proteins in CSF-arrested Xenopus oocytes and dissociation of the complex following oocyte activation.

Coimmunoprecipitation experiments using a monoclonal anti-centrin antibody (20H5) and cytostatic factor (CSF)-arrested Xenopus oocyte extracts specifically precipitates oocyte centrin (20-kDa) and two associated proteins of 70- and 90-kDa. Microsequence analysis of a tryptic peptide fragment of the 70-kDa protein reveals 100% identity with a 13-amino-acid peptide sequence from Xenopus heat shock protein hsp-70. Western blot analysis of immunoprecipitates using anti-hsp monoclonal antibodies (N27 and AC-88) confirms the identity of the 70-kDa protein as hsp-70 and identifies the 90-kDa protein as hsp-90. The centrin/hsp complex is also immunoprecipitated when anti-hsp-70 or anti-hsp-90 monoclonal antibodies (BB70 and 4F3, respectively) are used as primary antibodies during immunoprecipitation. The centrin/hsp complex is sensitive to pH and Ca2+ concentration. The complex shows differential dissociation of hsp-70 and hsp-90 under a variety of conditions, suggesting that each hsp can bind to centrin independently of the other. When oocytes are first activated by electric shock or ionophore treatment, followed by immunoprecipitation using anti-centrin monoclonal antibody 20H5, centrin precipitates with significantly reduced levels of hsp-70 in the complex, and these complexes contain no apparent hsp-90. We conclude that, in CSF-arrested oocytes, the centrosomal protein, centrin, is associated as a complex with the heat shock proteins, hsp-70 and hsp-90, and that this complex dissociates upon activation of the oocyte. The functional consequences of the formation of complexes between centrin and these hsps are unknown. However, based on the roles that have been defined for heat shock proteins in other systems, several possibilities are suggested.

Amino Acid Sequence↗
PubMed1994

Congenital cutis laxa with a dominant inheritance and early onset emphysema.

Two cases (mother and daughter) are reported of autosomal dominant cutis laxa which are unusual in being associated with early onset emphysema. Both mother and daughter have been smokers and are heterozygotes for the alpha 1 antitrypsin genotype. The combination of cigarette smoking and subnormal alpha 1 antitrypsin levels may explain the pulmonary spread in these two women who have what is usually a benign form of cutis laxa limited to the skin.

Adult↗
PubMed1993

Identification of a 60-kilodalton stress-related protein, p60, which interacts with hsp90 and hsp70.

Immunoaffinity purification of hsp90 from chick oviduct cytosol reveals two major proteins, hsp70 and a 60-kDa protein (p60), copurifying with hsp90. A similar result is obtained when hsp90 is immunoaffinity purified from chick liver and brain cytosols, avian fibroblasts, and rabbit reticulocyte lysate. This p60 is the same protein previously identified in certain assembly complexes of chick progesterone receptor generated in a cell-free reconstitution system. Tryptic and cyanogen bromide peptide fragments were generated from gel-purified p60, and partial N-terminal sequences were determined from eight peptides. The sequences show a striking similarity to the sequence of a 63-kDa human protein (IEF SSP 3521) whose abundance is increased in MRC-5 fibroblasts following simian virus 40 transformation. A monoclonal antibody was prepared against avian p60; Western immunoblot analysis showed that p60 was present in each of eight chick tissues examined and in each of the human, rat, rabbit, and Xenopus tissues tested. Immunoaffinity purifications from both chick oviduct cytosol and rabbit reticulocyte lysate using anti-p60 and anti-hsp70 monoclonal antibodies confirm that there is a relatively abundant complex in these extracts containing hsp90, hsp70, and p60. This complex appears to comprise an important functional unit in the assembly of progesterone receptor complexes. However, judging from the abundance and widespread occurrence of this multiprotein complex, hsp90, hsp70, and p60 probably function interactively in other systems as well.

Amino Acid Sequence↗
PubMed1992

Paradoxical early lengthening and subsequent linear shortening of the QT interval in response to exercise.

The QT responses to exercise during ventricular pacing were evaluated in 12 patients in whom permanent pacemakers were implanted for complete heart block. The initial response of the QT to exercise was a paradoxical lengthening during the first minute of exercise (mean 4.8 ms P < 0.01). Thereafter, the QT was found to shorten in a linear fashion in response to increasing exercise, both in terms of exercise duration (r = 0.787; P < 0.001) and atrial rate (r = 0.712; P < 0.001). The total QT shortening with exercise was small (20 ms for a mean increase in atrial rate of 60 beats.min-1) and displayed substantial inter-individual variability (9-31 ms). These results explain some of the limitations of the QT pacemaker, and provide insights in to the dynamics of the QT response, which may help tailor the programming of these systems to the individual patient.

Adult↗
PubMed1992

The effect of orthotopic transplantation on total, beta 1- and beta 2-adrenoceptors in the human heart.

1. [125I]-(-)pindolol binding was used to determine beta-adrenoceptor density in homogenate preparations of right ventricular endomyocardial biopsies from 43 non-rejecting patients over the first 13 months following cardiac transplantation. The selective beta 1 subtype antagonist ligand CGP 20712A was used to determine the subtype density in 32 of the patients. Biopsy specimens from 15 donor hearts were used as controls. 2. beta-adrenoceptor density (expressed in terms of fmol mg-1 protein) was increased in the group of transplanted hearts as a whole compared with the donor hearts with respect to total (35 +/- 2 vs 23 +/- 2) and the beta 1 subtype (25 +/- 2 vs 16 +/- 2) whereas the beta 2 subtype and radioligand dissociation constant did not differ. 3. Non-parametric analysis of variance of total receptor density over time revealed significant heterogeneity which appears to be due to a discrete increase in beta-adrenoceptor density during the 4th post operative month. 4. These results indicate that beta-adrenoceptor density is not constant following transplantation. Furthermore, the increase in receptor density following transplantation is due mainly to an increase in the beta 1 subtype without a significant change in the beta 2 subtype.

Adult↗
PubMed1992

Lung allograft transplantation: indications, preoperative assessment and postoperative management.

In spite of a shortage of available donors, an increasing number of heart-lung transplantations have been performed within the last decade. This procedure, first limited to patients with pulmonary vascular disease, has been successfully extended to patients with end stage lung disease, including cystic fibrosis. More recently, single lung, double-lung and bilateral single lung transplantation have become other therapeutic options. Better selection of patients and donors as well as improvements in surgical techniques and immunosuppression regimens have contributed to the reduction in the high perioperative mortality experienced in the early stages. Moreover, the introduction of daily spirometry and transbronchial lung biopsies have permitted early and reliable diagnosis of opportunistic infection and rejection. The most serious late complication of lung transplantation is obliterative bronchiolitis and further research is urgently required to improve diagnosis and management of this condition.

Graft Rejection↗