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M Bailey

Publications and source records attributed to M Bailey.

At least 145 records · Page 8Linked to original sources
PubMed1996

Expression of major histocompatibility complex class II antigens on normal porcine intestinal endothelium.

A novel monoclonal antibody (MIL 11) specific for an antigen expressed on porcine endothelial cells is described. The antigen recognized by MIL 11 is most strongly expressed in the intestine but is also expressed on the capillary endothelium of a wide range of tissues. Using two- and three-colour immunofluorescence microscopy we demonstrated the extensive coexpression of MIL 11 and major histocompatibility complex (MHC) class II antigens on normal porcine capillary endothelium in the intestine, trachea, thymus and small veins, while endothelium of large vessels and the heart were negative for MHC class II. In contrast to humans and rodents, available reagents do not detect MHC class II on the intestinal epithelium of pigs. However, porcine intestinal endothelium expressed both DR and DQ antigens. A population of strongly class II-positive cells was also detected immediately adjacent to the endothelium in the lamina propria. Three-colour immunofluorescence microscopy highlighted the close association between endothelium and intestinal CD4+ T cells. Lamina propria T cells were mainly MHC class II positive, whereas those in the epithelial compartment were MHC class II negative.

Animals↗
PubMed1996

Smoking cessation and lung cancer resection.

STUDY OBJECTIVE: This study was designed to examine the extent of smoking cessation prior to thoracotomy for resection of a pulmonary malignancy and the recidivism rate. DESIGN: Prospective, longitudinal study. PATIENTS: All patients presenting to the General Thoracic Clinic. RESULTS: The study included 362 patients, with an average age of 64.7 years; 95% with a smoking history were followed up for an average of 17.5 months. Five surgeons in the same practice group performed the procedures: pneumonectomy, 45; lobectomy, 288; and lesser resections, 29. Forty-two percent of patients had quit prior to 1 year; 6% quit 3 months to 1 year; 15% quit between 2 weeks to 3 months; 12% quit at 2 weeks; and 19% continued to smoke up to surgery. Postoperatively, 86% of previously smoking patients were nonsmoking; 13% of patients started smoking again. Of the restarted smoking patients, 61% had never quit preoperatively. Only 59% of smoking patients admitted that a physician had ever told them to stop smoking; however, 89% of patients who were smoking postoperatively acknowledged physician advice to stop smoking. CONCLUSIONS: Long-term smoking cessation occurs in a large proportion of patients after resection of lung cancer. The longer the patient is nonsmoking preoperatively, the more likely he or she is to remain nonsmoking postoperatively. Conversely, patients who do not quit preoperatively are at significant risk of continuing to smoke postoperatively.

Female↗
PubMed1995

Interaction between the Escherichia coli Regulatory protein TyrR and DNA: a fluorescence footprinting study.

The Escherichia coli regulatory protein TyrR controls the expression of eight transcription units that encode proteins involved in the biosynthesis and transport of aromatic amino acids. It is a homodimer of 57 600 subunit molecular weight and has a binding site for ATP and weak ATPase activity. In the presence of ATP, TyrR binds tyrosine, which induces self-association of TyrR from a dimer to a hexamer. This report examines the interaction of TyrR with a 42 bp DNA oligonucleotide containing a centrally located binding site for TyrR (TyrR box). Replacement of a thymidine residue with an aminouridine residue at positions 7, 9, 13, 15, 19, 22, and 26 from one end of the 42mer enables labeling with fluorescein and successive placement of the label along the major groove of the DNA. The fluorescence footprinting of the oligonucleotide was followed using steady-state and time-resolved fluorescence methods. Binding of the TyrR dimer caused significant changes in the fluorescent properties of the labels attached to positions 13, 15, and 26, suggesting the involvement of these bases in the binding of the protein. Except for the position 15 conjugate, binding of the TyrR dimer caused little change in fluorescence intensity. Therefore, fluorescence anisotropy was used to follow the binding equilibrium. The fluorescence of the position 15 conjugate increased 1.6-fold on binding TyrR, suggesting that the fluorophore was in close contact with the protein. For all conjugates, the addition of tyrosine at the end of the titration with TyrR increased the anisotropy markedly, suggesting that the hexameric form of TyrR could bind the oligonucleotide. Two rotational correlation times were found for the labeled conjugates: one reflecting the motion of the probe at its point of attachment to the DNA (220-290 ps), the other reflecting the global tumbling of the labeled oligonucleotide (14-21 ns). On binding TyrR, changes in the correlation times and their associated amplitudes and changes in the range of angular motion of the probe depended on the position of the label. Evidence is presented that the binding of the TyrR hexamer, but not the TyrR dimer, affects regions that flank the binding sequence. The results support the hypothesis that the binding of the TyrR hexamer is responsible for interaction between tandem TyrR boxes in the tyrR regulon.

Base Sequence↗
PubMed1995

Synthesis and characterisation of fluorescent oligonucleotides. Effect of internal labelling on protein recognition.

Fluorescently labelled 42 base pair DNA duplexes were synthesised to examine the interaction between the TyR repressor protein of Escherichia coli and its DNA recognition sequence. An Fmoc-protected 5-(3-aminoprop-l-yn-l-yl)-2'-deoxyuridine phosphoramidite was synthesised and incorporated into oligonucleotides using standard beta-cyanoethyl phosphoramidite chemistry. Oligonucleotides containing the 3-aminopropynyl nucleotide at internal positions were reacted with fluorescein isothiocyanate to generate fluorescent DNA molecules useful for characterising interactions between DNA and proteins. Short DNA duplexes were investigated with respect to their melting temperatures and their ability to bind TyrR. Oligonucleotides containing a TyrR binding site were labelled in the central region of the recognition sequence or near the 5' edge of the recognition sequence. Fluorescein-labelled oligonucleotides could hybridise to form duplex DNA, and gel retardation experiments showed that the presence of the dye did not alter the binding affinity for the TyrR protein significantly. Fluorescence anisotropy measurements were used to examine the binding equilibrium in low and high salt buffers. A dissociation constant of 200-500 nM was obtained for the interaction of the TyrR dimer with a 42 bp duplex containing a centrally located 22 bp TyrR binding site.

Amides↗
PubMed1995

Effect of early weaning on the development of immune cells in the pig small intestine.

The controlled effects of age and weaning on the numbers of CD2+ T cells, subsets (CD4+, CD8+), accessory cells (macrophage/granulocyte) and cells expressing MHC class II (DQw) and IL-2R in the piglet intestine was investigated. At birth low numbers of CD2+CD4-CD8- cells were the only demonstrable T cells in the intestine. Monocyte/granulocyte and MHC class II+ cells were also detected in low numbers and IL-2R+ cells were proportionally quite numerous. All those cell populations, except the IL-2R+ cells, increased thereafter and peaked at Week 7 when the numbers of cells were comparable with those of adult animals. CD4+ cells increased dramatically after Week 1. In contrast, CD8+ remained scarce until after 5-7 weeks of age in unweaned animals. Four days after weaning at 3 weeks old, there were increases in CD2+ (P < 0.001) and macrophage/granulocyte (P < 0.01) cells in proximal small intestinal villi and in CD2+ cells only (P < 0.01) in crypts. No significant changes in cell numbers were demonstrated in the distal small intestine.

Aging↗
PubMed1995

Presentation of soluble and bacterial antigens by milk-derived cells to unprimed bovine T cells in vitro.

The ability of cells isolated from bovine milk and peripheral blood to present soluble protein and particulate bacterial antigens to peripheral blood T lymphocytes was compared using a culture system which consistently supports antigen-specific, primary, proliferative responses. The present study shows that cells from blood and from milk can present antigen to unprimed T cells. Major histocompatibility complex class II restriction of the responses was demonstrated by abrogation of proliferation by the addition of anti-bovine class II monoclonal antibody to cultures. Although cells derived from blood or milk were shown to be capable of presenting antigen to T cells, differences in optimal culture conditions and kinetics of the resulting response were observed.

Animals↗
PubMed1995

A successful backcross in Trypanosoma brucei.

Genetic exchange can take place between different strains of Trypanosoma brucei ssp. when they are cotransmitted via the tsetse fly vector, but the mechanism and limits of compatibility between strains are ill-defined as yet. Following the recovery of several hybrid genotypes with single drug resistance from a cross of drug resistant parental strains, we attempted a series of backcrosses and F1 crosses, selecting hybrids by double drug resistance. Of 4 backcrosses, one produced hybrid progeny, the analysis of which is presented here, but none of the 4 F1 crosses produced hybrid progeny. However, among experimental flies from the 8 crosses, although there were large numbers of salivary gland infections, very few consisted of a mixture of parental clones, a prerequisite for mating. In the successful backcross both parents were diploid, but none of the crosses involving triploid clones produced hybrid progeny. The hybrid-secreting fly from the backcross contained a mixture of hybrid and parental clones. The hybrid clones had approximately 3n DNA contents relative to the 2n parental clones and fell into 2 groups with respect to restriction site polymorphisms in kinetoplast DNA maxi-circles. Fingerprinting by random PCR amplification using 8 different arbitrary primers showed minor variation between the hybrid clones.

Animals↗
PubMed1995

31P-nuclear magnetic resonance studies of chronic myocardial ischemia in the Yucatan micropig.

In this work, an x-irradiation/high fat/high cholesterol diet-induced atherogenic model was invoked to examine the effects of severe diffuse atherosclerosis on myocardial metabolism in the in vivo porcine heart. This model was studied using spatially localized 31P-nuclear magnetic resonance (NMR) to monitor pH and the levels of inorganic phosphate, phosphomonoesters, creatine phosphate, and adenosine triphosphate as a function of workload transmurally in control swine and in animals suffering from chronic ischemic heart disease. These preliminary studies revealed that the development of severe atherosclerosis and the accompanying chronically diseased state produce changes in high energy phosphates and that increases in rate pressure products result in demonstrable signs of ischemia in the myocardium which span the entire left ventricular wall. Ischemic changes include a global increase in inorganic phosphate and corresponding decreases in creatine phosphate, ATP, and pH. Importantly, changes in intracellular pH are noted with even the slightest increase in workload suggesting that these diseased hearts display elevated glycolytic activity. By challenging these animals with increased cardiac workload, we directly visualize how the chronically compromised heart responds to severe oxygen challenges in a clinically relevant model of this situation.

Animals↗
PubMed1995

Effects of monovalent cations, pH and temperature on the dissociation constant (KD) for the fluorescent indicator mag-fura-2 at different excitation wavelengths.

The use of fluorescent indicators to quantify intracellular magnesium ([Mg(2+)]i) requires accurate determination of the dissociation constant (K(D)). Ideally, the K(D) should be determined intracellularly; however, in practice this is difficult to achieve. An alternative method is to measure the K(D) in solutions which attempt to mimic the intracellular milieu. This study investigated the effect of monovalent cations, pH and temperature on the Mg(2+)-mag-fura-2 K(D) determined at individual excitation wavelength intensities of either 340 nm or 380 nm, with emission fluorescence set at 510 nm. Monovalent cation concentration had little effect on K(D). Temperatures in the range 25 degrees C to 37 degrees C had significant effects on K(D) measured at 340 nm and 380 nm. At 340 nm the K(D) values at 25 degrees C and 37 degrees C were 2.02 and 1.15 mM, respectively and at 380 nm 2.84 to 1.68 mM, respectively. Changes of pH in the range 6.5 to 8.5 had variable effects on the K(D) depending on the wavelength at which it was measured. The results illustrate not only how estimation of K(D) can vary with environmental conditions, including temperature and pH. but also the choice of wavelength.

Fluorescent Dyes↗
PubMed1994

Characterization of monoclonal antibodies specific for monocytes, macrophages and granulocytes from porcine peripheral blood and mucosal tissues.

A panel of four monoclonal antibodies produced in our laboratory, MIL1, MIL2, MIL3, MIL4, and the type-specific monocyte/granulocyte marker 74-22-15 were used to isolate and to discriminate between monocytes, macrophages and granulocytes derived from porcine peripheral blood, lung and gut lamina propria. Two-colour flow cytometry and cell sorting showed that while no monoclonal antibody was specific for just a single cell population, each cell type had a unique and characteristic combination of surface antigens. These differences could be used to identify and purify monocytes, macrophages, neutrophils, eosinophils and basophils from the three different sites. The study also demonstrated similarities and differences within cell types from the same site and from different sites: polymorphonuclear neutrophils (PMN) from peripheral blood were subdivided into two subpopulations by the presence or absence of the surface antigen recognized by MIL4, while PMN from alveolar lavage did not express this antigen. Peripheral blood eosinophils were also divided into subpopulations by the presence or absence of the same surface antigen. Lamina propria eosinophils strongly expressed the MIL4 marker and differed morphologically from blood eosinophils. Peripheral blood basophils and lamina propria mast cells were morphologically similar and expressed similar antigens. Monocytes and alveolar macrophages also expressed the same surface antigens.

Animals↗
PubMed1994

DNA content and molecular karyotype of trypanosomes of the subgenus Nannomonas.

The relative DNA contents of representative stocks of 5 groups within the trypanosome subgenus Nannomonas (Trypanosoma simiae, Godfreyi, T. congolense Savannah, Forest and Kilifi) were measured by flow cytometry. The range of DNA contents formed a continuum. Nevertheless small differences were observed between the groups, with T. simiae/T. congolense Savannah and T. congolense Kilifi/Forest at the lower and higher ends of the range respectively. Analysis of karyotype by pulsed field gel electrophoresis showed all the 5 Nannomonas groups to have minichromosomes and variable numbers of small chromosomes in the 100-700 kb size range. The size and relative number of mini-chromosomes varied from group to group, but no correlation between molecular karyotype and DNA content was observed.

Animals↗
PubMed1994

Immunology of the porcine gastrointestinal tract.

The gastrointestinal immune system is presented with a contrasting array of antigens, ranging from harmless dietary components to highly pathogenic microorganisms. The mucosal immune system has the ability to recognise different groups of antigens and has evolved a battery of responses from which an appropriate response may be orchestrated. The question as to how the mucosal immune system categories antigens and selects a particular response is central to this process but it remains largely unanswered. The solution to this question is likely to hold the key to the development of safe and effective mucosal vaccines as well as suggesting methods for the prevention and control of allergic responses. Enteric diseases resulting from antigens (microbial and dietary) presented via the gastrointestinal tract are a major cause of morbidity and mortality. In addition to being of substantial economic importance, growing public awareness on animal welfare and food quality confirms the urgent need for new methods of disease control.

Animals↗