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J O'Mullane

Publications and source records attributed to J O'Mullane.

11 recordsLinked to original sources
PubMed2001

Quantification of red blood cells using atomic force microscopy.

For humans the sizes and shapes of their red blood cells are important indicators of well being. In this study, the feasibility of using the atomic force microscope (AFM) to provide the sizes and shapes of red blood cells has been investigated. An immobilisation procedure has been developed that enabled red blood cells to be reliably imaged by contact AFM in air. The shapes of the red blood cells were readily apparent in the AFM images. Various cell quantification parameters were investigated, including thickness, width, surface area and volume. Excellent correlation was found between the AFM-derived immobilised mean cell volume (IMCV) parameter and the mean cell volume (MCV) parameter used in current haematological practice. The correlation between MCV and IMCV values has validated the immobilisation procedure by demonstrating that the significant cell shrinkage that occurs during immobilisation and drying does not introduce quantification artifacts. Reliable IMCV values were obtained by quantifying 100 red blood cells and this typically required 3-5 AFM images of 100 microm x 100 microm area. This work has demonstrated that the AFM can provide in a single test the red blood cell size and shape data needed in the assessment of human health.

Anemia, Macrocytic↗
PubMed2001

Quantifying complement-mediated phagocytosis by human monocyte-derived macrophages.

The present study demonstrates that SRBC can be opsonized with untreated human serum such that lysis by active complement components is minimal but sufficient opsonization occurs to permit high rates of complement-mediated phagocytosis. Phagocytosis of SRBC opsonized with 2% whole human serum by human monocyte-derived macrophages was quantified in a colourimetric assay. Ingestion of SRBC was shown to occur solely via complement receptors because no phagocytosis was observed when SRBC were coated with heat- inactivated human serum, phagocytosis was augmented by the phorbol ester, PMA, and phagocytosis was inhibited by a protein kinase C (PKC)-specific inhibitor RO 31-8220. This method was used to demonstrate directly that HIV-1 infection of human monocyte-derived macrophages inhibits complement-mediated phagocytosis and will provide a useful tool for pharmacological investigations on complement-mediated phagocytosis by adherent macrophages.

Animals↗
PubMed2000

High-molecular-weight hydroxypropylmethylcellulose taken with or between meals is hypocholesterolemic in adult men.

Hydroxypropylmethylcellulose (HPMC) is a food gum that shares certain characteristics, such as high viscosity, with soluble fibers. In this trial, the safety and cholesterol-lowering efficacy of HPMC consumed with and between meals was evaluated in free-living male volunteers with mild-to-moderate hypercholesterolemia. After a 14-d baseline period, men (n = 51) with LDL cholesterol between 3.36 and 4.91 mmol/L and triglycerides <3.95 mmol/L were randomly assigned to consume 5.0 g/d HPMC in 240 mL of orange drink, taken either with or between meals, for a 2-wk treatment period. In the Between Meals group, total cholesterol was reduced by 8.0% vs. baseline in wk 1 of treatment (P < 0.05) and 5.1% in wk 2 (P < 0.01). LDL cholesterol concentrations fell by 12.0 and 7.7% (P < 0.01). In the With Meals group, reductions were 9.5 and 8.3% for total cholesterol, and 12.5 and 12.8% for LDL cholesterol (wk 1 and 2, respectively, P < 0.01). In both groups, HDL cholesterol decreased by approximately 5% during wk 1 of treatment (P < 0.01), but the wk 2 concentrations were not significantly different from baseline. There were no significant differences between groups in lipid responses, although there was a trend for a smaller LDL cholesterol-lowering effect during wk 2 of treatment in the Between Meals group (P < 0.06). Gastrointestinal-related adverse experiences (mostly mild) were twice as common among participants who ingested HPMC with meals (P < 0.05). These results suggest that HPMC has a lipid-lowering effect, which may be more consistent when taken with meals.

Adult↗
PubMed1999

Cholesterol lowering with high-viscosity hydroxypropylmethylcellulose.

Hydroxypropylmethylcellulose (HPMC) is a food gum having several structural and functional properties in common with hypocholesterolemic soluble fibers. The safety and cholestero-lowering efficacy of HPMC, incorporated into a National Cholesterol Education Program Step I diet, was compared with placebo in patients with mild to moderate hypercholesterolemia. After an 8-week National Cholesterol Education Program Step I dietary lead-in phase, 160 patients with low-density lipoprotein (LDL) cholesterol between 130 and 200 mg/dl and triglycerides <300 mg/dl were randomized to placebo, 2.5, 5.0, or 7.5 g/day of HPMC for a 6-week treatment period. Patients returned to the clinic every 2 weeks for lipid measurements and safety assessments. HPMC significantly lowered total, LDL, and non-high-density lipoprotein (HDL) cholesterol. LDL cholesterol concentrations (average of weeks 4 and 6) decreased by 3.0% (4.9 mg/dl), 5.9% (10.3 mg/dl), 12.1% (20.4 mg/dl), and 11.7% (20.3 mg/dl) from baseline levels in the placebo and 2.5, 5.0, and 7.5 g/day HPMC treatment groups, respectively. Statistically significant (p<0.05) reductions in LDL cholesterol were observed in the 5.0 and 7.5 g/day HPMC groups compared with placebo and 2.5 g/day HPMC treatment groups. Total and non-HDL cholesterol responses paralleled those of LDL cholesterol. There were no significant differences between the treatment groups in HDL cholesterol or triglyceride responses, incidence of adverse experiences, or gastrointestinal-related adverse experiences. These results suggest that HPMC is a well-tolerated and effective adjunct to diet for lowering LDL cholesterol in patients with mild to moderate hypercholesterolemia.

Adult↗
PubMed1995

Detection of the heat-stable toxin coding gene (ST-gene) in enterotoxigenic Escherichia coli: development of a colour amplified PCR detection system.

Screening biological samples using the polymerase chain reaction (PCR) has obvious advantages compared with current molecular analytical methods based on gel electrophoresis and/or hybridisation, both of which are expensive and time-consuming, therefore the development of a PCR assay format that is applicable to large sample numbers and that can readily use equipment commonly found in diagnostic laboratories would be advantageous. This report describes the development of a colour amplified PCR detection system which is simple in design and could be universally applied to the detection of any DNA template. As an example, the system has been applied in the detection of the heat-stable toxin coding gene (ST-gene) from enterotoxigenic Escherichia coli (ETEC). The assay is sensitive, detecting 10 fg of a purified DNA template and 270 cfu of an ST-gene-positive ETEC strain.

Bacterial Toxins↗
PubMed1991

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

When dissolved in N,N-dimethylformamide and then dialyzed against phosphate-buffered saline, A-B-A block copolymers composed of poly [N5-(2-hydroxyethyl)-L-glutamine]-block-poly(gamma-benzyl-L-glutamate)- block-poly [N5-(2-hydroxyethyl)-L-glutamine] form particles. The particles are cage-like structures with average diameters of 300 nm (average polydispersity, 0.3-0.5). They are stable in aqueous solution at 4 degrees C for up to 3 weeks, at which time flocculation becomes apparent. Negative staining and freeze-fracture electron microscopy suggest that cage-like particles are formed by selective association of segregated micelle populations. A model of particle formation is presented in which B blocks form micelles in dimethylformamide. On dialysis against an aqueous solution, the extended A blocks then associate intermolecularly to form rod-shaped micelles, which connect the B block micelles. The result is a meshed cage-like particle. The implications of these observations on the aggregation behavior of polymeric surfactants in dilute solution are discussed.

Journal Article↗
PubMed1991

R-[N-acetyl]eglin c:poly(oxyethylene) conjugates: preparation, plasma persistence, and urinary excretion.

In this paper, we describe the preparation, purification, and characterization of conjugates of R-[N-acetyl]eglin c (Eglin c) with poly(oxyethylene) (POE; Eglin c:POE). The plasma profile and urinary excretion of the conjugates has been determined after iv administration in mice. The modification of Eglin c with POE does not significantly impair the ability of Eglin c to bind elastase as measured by an in vitro assay. In the best example, 79% of theoretical activity was retained by the conjugate. The in vivo results clearly show that the amount of Eglin c:POE in plasma after iv administration is much higher than comparative doses of unconjugated Eglin c. The time course of the plasma concentration of the conjugate matches closely that of the corresponding free polymer. Consequently, we can expect that higher plasma concentration could be achieved, if and when required, by selecting polymers of appropriate size.

Amino Acid Sequence↗
PubMedDate not supplied

Applications of the polymerase chain reaction (PCR) in diagnosis.

This paper reports on three applications of the polymerase chain reaction (PCR) in the pathology laboratory, cystic fibrosis carrier status investigation, Staphylococcus aureus identification and HLA-DQ alpha tissue typing. Allele specific PCR was used to detect the common cystic fibrosis mutation (delta F508) in an Irish family. The genomic status of each member was shown to be either heterozygous (carrier) or homozygous (affected) for the mutation, based on the resolution of allelic amplifications in an agarose gel. Five staphylococci were subjected to PCR designed to amplify a 137 bp DNA fragment from the S. aureus protein A gene (spa). Four isolates gave a coloured "dot-blot" positive signal, the fifth was negative. In the final application the HLA-DQ alpha region was amplified using DNA obtained from four unrelated individuals. Amplified DNA was tissue typed in a reverse "dot-blot" format. All individuals had unique HLA-DQ alpha types. These examples have been chosen to demonstrate the versatility of this technique and to illustrate some of its potential applications.

Alleles↗