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Biomedical subjects

M Phillips

Publications and source records attributed to M Phillips.

At least 37 records · Page 2Linked to original sources
PubMed1992

Monophosphoryl lipid A-induced immune enhancement of Brucella abortus salt-extractable protein and lipopolysaccharide vaccines in BALB/c mice.

A study was conducted to determine the effect of monophosphoryl lipid A (MPL) and trehalose dimycolate (TDM) as adjuvants on the protective responses in BALB/c mice vaccinated with Brucella abortus salt-extractable protein (BCSP) or proteinase-K-treated B abortus lipopolysaccharide (PKLPS). Mice were vaccinated with different doses of BCSP or PKLPS given alone or in combination with MPL or TDM. Mice were challenge-exposed 4 weeks later with virulent B abortus strain 2308. Two weeks after challenge exposure, the number of B abortus colony-forming units (CFU) per spleen, spleen weights, and spleen cell interleukin 1 production were measured. Serum IgG and IgM concentrations specific for vaccinal immunogens were measured before and after challenge exposure with B abortus. Spleen weights and mean B abortus CFU per vaccine group were significantly lower in BCSP- and PKLPS-vaccinated mice, compared with those of nonvaccinated control mice. Monophosphoryl lipid A enhanced the suppression of splenic infection when given with the BCSP vaccine, but not when given with the PKLPS vaccine. Trehalose dimycolate had no effect on mean CFU when given with BCSP, but incorporation of TDM resulted in a significant increase in mean CFU when given with PKLPS. Spleen weights in BCSP- or PKLPS-vaccinated mice were not different when these vaccines were combined with MPL or TDM. Because of the wide variation in the results, we could not conclude that vaccination with BCSP or PKLPS alone, or in combination with MPL altered spleen cell interleukin-1 production in B abortus-infected mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1992

Identification of a neutral lipid core in a transiently expressed and secreted lipoprotein containing an apoB-48-like apolipoprotein.

The presence of core lipids in lipoproteins expressed and secreted by transfected HepG2 cells was demonstrated by measuring the densities of these lipoproteins before and after treatment with a bacterial lipase specific for neutral lipids. HepG2 cells were reproducibly transfected with pRSV/B48, containing a truncated human apolipoprotein B-100 (apoB-100) cDNA (nucleotides 1 to 6860, where nucleotide 129 is the start of translation). Northern blots of cellular message probed with apoB-48 showed abundant transcription of an apoB-48-sized message as well as endogenous apoB-100 message. When grown in the presence of [35S]methionine, pRSV/B48-transfected cells secreted lipoproteins containing an apoB-48-like apolipoprotein. This lipoprotein banded at a density of 1.11 g/ml in isopycnic NaBr gradients. Electron microscopy of the apoB-48-containing lipoproteins demonstrated spherical particles with an average diameter of 124A. A sedimentation rate of 8.4S was measured by sucrose gradient sedimentation. When the apoB-48-containing particles were treated with a bacterial lipase (from Chromobacterium viscosum), shown to hydrolyze triglycerides and cholesteryl esters but not phospholipids, their density increased to 1.18 g/ml, consistent with removal of core lipids. When the secreted lipoprotein was modeled as a spherical particle containing a single molecule of apoB-48, a triglyceride-filled core, and a surface monolayer of phospholipid and protein, the hydrodynamic properties were consistent with the observed sedimentation coefficient, buoyant densities before and after lipase treatment, and the diameter as seen with the electron microscope. These data indicate that transfected HepG2 cells assembled and secreted lipoproteins possessing the same physical structure as naturally occurring lipoproteins.

Apolipoprotein B-48↗
PubMed1992

Ion-trap detection of volatile organic compounds in alveolar breath.

We describe a method for the collection and microanalysis of the volatile organic compounds in human breath. A transportable apparatus supplies subjects with purified air and samples their alveolar breath; the volatile organic compounds are captured in an adsorptive trap containing activated carbon and molecular sieve. The sample is thermally desorbed from the trap in an automated microprocessor-controlled device, concentrated by two-stage cryofocusing, and assayed by gas chromatography with ion-trap detection. Compounds are identified by reference to a computer-based library of mass spectra with subtraction of the background components present in the inspired air. We used this device to study 10 normal subjects and determined the relative abundance of the volatile organic compounds in their alveolar breath. The breath-collecting apparatus was convenient to operate and was well tolerated by human volunteers.

Air Pollutants↗
PubMed1991

Isolation from commercial aurintricarboxylic acid of the most effective polymeric inhibitors of von Willebrand factor interaction with platelet glycoprotein Ib. Comparison with other polyanionic and polyaromatic polymers.

Solutions of commercial aurintricarboxylic acid (ATA) inhibit ristocetin- or shear stress-induced, von Willebrand factor (vWF)-mediated platelet aggregation by interacting with vWF and blocking its attachment to platelet membrane glycoprotein Ib. ATA has also been shown to prevent cyclic platelet clumping in a dog model of coronary artery thrombosis. Because these ATA solutions are actually a heterogeneous mixture of polyanionic, polycarboxylic polyaromatic polymers of molecular weight (Mr) 200 to greater than 6,000, we separated the most effective inhibitory components of commercial ATA using exclusion chromatography. ATA polymers larger than Mr 700 inhibited ristocetin-induced, vWF-mediated platelet aggregation more effectively than smaller ATA polymers, whereas shear-induced, vWF-mediated platelet aggregation was optimally inhibited by ATA polymers of Mr greater than or equal to 2,500. Platelet aggregation mediated by vWF was not inhibited by a nonphenolic, polyanionic polymer (polyglutamic acid) or by a polyphenolic ATA-like polymer (aurin) devoid of carboxyl groups. Polyanionic, polysulfonated aromatic polymers (polystyrene sulfonate) of Mr 35, 17.4, 8, and 4.6 x 10(3) inhibited ristocetin- and shear-induced, vWF-mediated aggregation with less potency on a mass/volume basis than large polymers of ATA. We conclude that a polyanionic, polycarboxylated, polyphenolic ATA polymer of Mr 2,500 is optimally potent as an inhibitor of shear- and ristocetin-induced, vWF-mediated platelet aggregation and is likely to be more effective than solutions of commercial ATA as an anti-arterial thrombotic agent.

Adenosine Diphosphate↗
PubMed1991

Method for the collection and analysis of volatile compounds in the breath.

A new method is described for the collection and assay of volatile compounds in the breath. Subjects expired into a pump-assisted collecting apparatus in which the breath was drawn through a water trap and then through an adsorptive trap where the volatile compounds were captured on graphitized carbon and molecular sieve. The sample was subsequently eluted from the trap by thermal desorption, concentrated by two-stage cryofocusing, then assayed by gas chromatography with flame ionization and flame photometric detection. Several compounds were regularly observed in the breath of normal human volunteers, including peaks eluting with the same retention times as isoprene, ethanol, acetone, acetaldehyde and carbon disulfide. As a quantitative assay for endogenous isoprene in the breath, the method was sensitive, linear, accurate and reproducible. This method provided a number of advantages: the collection technique was acceptable to volunteers and could be used at sites remote from the laboratory. The automated assay allowed isoprene and several other volatile compounds in the breath to be observed consistently and with improved sensitivity.

Acetaldehyde↗
PubMed1991

A comparison of phenotype and copper distribution in blotchy and brindled mutant mice and in nutritionally copper deficient controls.

The murine mottled mutants brindled, Mo br, and blotchy, Mo blo, are valuable animal models for the study of mammalian copper metabolism. In this paper, we present data showing that a nutritionally copper deficient suckling mouse, Cu-, with strong phenotypic similarities to the brindled mutant can be produced by feeding genetically normal dams a copper deficient diet (0.1-0.4 ppm Cu2+) from the day of mating. Comparisons of copper distribution between the Cu- mice and brindled mutants indicate that when a small dose of copper (0.5-0.9 micrograms Cu2+) was administered by intracardiac injection, the copper was abnormally distributed, and that the pattern of tissue distribution was very similar in Cu- mice and brindled mutants 24 h after injection. When, however, a treatment dose (50 micrograms Cu2+) was injected subcutaneously, and tissues assayed 3 d after injection, copper distribution in Cu- mice and brindled mutants was clearly different. Copper deficiency in Cu- suckling mice is entirely derived from maternal effects. Evidence that maternal effects may also influence the survival and phenotype of the brindled and blotchy mutants was obtained by comparing the viability of mutants born to dams carrying mottled mutations on one or both X chromosomes.

Animals↗
PubMed1991

Unresponsiveness of vaccinated BALB/c mice to a second inoculation of lipopolysaccharide from Brucella abortus strain 2308.

A study was conducted to determine whether the protection induced in mice by a primary inoculation of lipopolysaccharide from Brucella abortus would be enhanced by a second inoculation given at different time intervals. Protection was challenged by exposure of the mice to a virulent culture of B. abortus strain 2308. Reduced mean viable count and/or splenic weights were the criteria of protection. There was no significant difference (P greater than 0.05) in the protective responses among mice given a single inoculation. Vaccinated mice were significantly (P less than 0.05) better protected than were nonvaccinated mice. Mice given vaccinal inoculations simultaneous with challenge exposure were less protected (P less than 0.001) than were mice vaccinated prior to challenge, but were better protected (P less than 0.010) than were nonvaccinated mice.

Animals↗
PubMed1991

Polymorphism due to variable number of repeats in the human involucrin gene.

The coding region of the involucrin gene in higher primates contains a segment consisting of numerous tandem repeats of a 10-codon sequence. The process of repeat addition began in a common ancestor of all higher primates and subsequent repeats were added vectorially. As a result, the principal site of repeat addition has moved in the 3' to 5' direction and the most recently generated repeats (the late region) are close to the 5' end of the segment of repeats. In the human, most of the late region is made up of two different blocks, each consisting of nearly identical repeats. We describe here five polymorphic forms resulting from the addition of differing numbers of repeats to each block. As the variety and nature of the polymorphic alleles are different in different human populations, we postulate that the process of repeat addition is genetically determined.

Alleles↗
PubMed1991

The involucrin genes of the white-fronted capuchin and cottontop tamarin: the platyrrhine middle region.

In all anthropoid species, the coding region of the involucrin gene contains a segment of short tandem repeats that were added sequentially, beginning in a common anthropoid ancestor. The involucrin coding region of each of two platyrrhine species, the white-fronted capuchin (Cebus albifrons) and the cottontop tamarin (Saguinus oedipus), has now been cloned and sequenced. These genes share with the genes of the catarrhines the repeats added in the common anthropoid lineage (the early region). After their divergence, the platyrrhines, like the catarrhines, continued to add repeats vectorially 5' of the early region, to form a middle region. The mechanism that was established in the common anthropoid lineage for the addition of repeats at a definite site in the coding region was transmitted to both platyrrhines and catarrhines, enabling each to generate its middle region independently. The process of vectorial repeat addition continued in two platyrrhine sublineages after their divergence from each other.

Animals↗
PubMed1991

Acute myeloid leukaemia in childhood: the costs and benefits of intensive treatment.

Response to treatment and resource implications were compared in two groups of children with acute myeloid leukaemia (AML) treated during consecutive periods. Event-free survival at 5 years improved from 12% (SE 3.4) during 1972-82 (group A) to 45% (SE 6.9) during 1983-87 (group B). The median time spent in hospital increased from 35 to 170 d. Allogeneic marrow transplantation was offered to all eligible children in group B. Eleven of the 53 children had a suitable donor and 10 proceeded to bone marrow transplantation (BMT). The relapse rate was lower after BMT than after chemotherapy, although not significantly so. We conclude that there has been a real improvement in prognosis for children with AML; that modern treatment requires intensive hospital resources and that these results should encourage further efforts to improve outlook and to explore treatments not involving radiation.

Acute Disease↗
PubMed1991

Establishment of dose-response relationships in BALB/c mice, using Brucella cell surface protein and lipopolysaccharide.

A study was conducted to determine the immune (increased antibody) and protective (reduced colony-forming units) responses induced in mice by a: (i) single vaccinal inoculation, using various concentrations of Brucella cell surface protein (BCSP) or lipopolysaccharide (LPS); (ii) primary inoculation, using various concentrations of BCSP, followed by a secondary inoculation, using a standard concentration of BCSP; and (iii) primary inoculation, using 1 concentration of BCSP or LPS, followed by a secondary inoculation, using various concentrations of BCSP or LPS. Four weeks after the primary inoculation, mice were challenge exposed with approximately 1 x 10(4) colony-forming units of Brucella abortus strain 2308 and all mice were euthanatized at 6 weeks. Reduced splenic weights and reduced colony-forming units in the spleens of vaccinated mice, compared with nonvaccinated mice, were the criteria of protection. Increase in serum IgM and IgG was defined as immunity. Both BCSP and LPS induced protective and immune responses that were proportional to the dose given up to an optimal limit. However, concentrations higher than optimal decreased the protective and immune responses. This was true for mice given either 1 or 2 vaccinal inoculations. Enhanced secondary protective responses were seen only when suboptimal doses were used in the primary inoculation. Excessive or optimal doses in the secondary inoculations prevented or obscured the protectiveness and immunity by primary inoculations. The protective effects appeared to be additive when suboptimal doses were used in the primary and secondary inoculations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The involucrin gene of the galago. Existence of a correction process acting on its segment of repeats.

The involucrin gene of the galago, a prosimian, has been cloned and sequenced. The coding region contains a segment of repeats homologous to the segment of repeats in the gene of another prosimian, the lemur, and different from the segments of repeats in the genes of higher primates. The repeats lengths in the two prosimians are similar; and except for a single duplication of a block of repeats in the lemur alone, the number of repeats is the same. However, the nucleotide consensus sequences of the repeats differ between the two species at 3 out of 39 nucleotide positions. The repeats therefore appear to have been modified by a correction process that led toward homogeneity in the repeats of each species while permitting divergence between the two species. The correction process, an example of concerted evolution, has taken place preferentially between adjacent repeats. The numerous differences between the segments of repeats of higher primates and the segments of repeats of lower animals reveal a discontinuity in the evolutionary processes acting on the gene.

Animals↗
PubMed1990

Immunochemical probing of the N-terminal segment on actin: the polymerization reaction.

The N-terminal segment of actin contains a cluster of acidic residues which are implicated in macromolecular interactions of this protein. In this work, the interrelationship between the N-terminal segment and the polymerization of actin was studied by using affinity-purified antibodies directed against the first seven N-terminal residues on alpha-skeletal actin (S alpha N). The Fab fragments of these antibodies showed equal affinities for G- and F-actin while the bivalent IgG bound preferentially to the polymerized actin. As monitored by pyrene fluorescence measurements, the binding of Fab to G-actin did not alter the kinetics of the MgCl2-induced polymerization; IgG accelerated this reaction considerably. Consistent with these observations, the binding of Fab to F-actin did not change its morphological appearance in electron micrographs and had no effect on the stability and the rate of dissociation of actin filaments. These results are discussed in terms of their implications to the spatial relationship between the N-terminal segment and the rest of the molecule and the context of the polymerization reaction of actin in vitro and in vivo.

Actins↗
PubMed1990

Ryanodine receptor gene is a candidate for predisposition to malignant hyperthermia.

Malignant hyperthermia (MH) is a potentially lethal condition in which sustained muscle contracture, with attendant hypercatabolic reactions and elevation in body temperature, are triggered by commonly used inhalational anaesthetics and skeletal muscle relaxants. In humans, the trait is usually inherited in an autosomal dominant fashion, but in halothane-sensitive pigs with a similar phenotype, inheritance of the disease is autosomal recessive or co-dominant. A simple and accurate non-invasive test for the gene is not available and predisposition to the disease is currently determined through a halothane- and/or caffeine-induced contracture test on a skeletal muscle biopsy. Because Ca2+ is the chief regulator of muscle contraction and metabolism, the primary defect in MH is believed to lie in Ca2+ regulation. Indeed, several studies indicate a defect in the Ca2+ release channel of the sarcoplasmic reticulum, making it a prime candidate for the altered gene product in predisposed individuals. We have recently cloned complementary DNA and genomic DNA encoding the human ryanodine receptor (the Ca2(+)-release channel of the sarcoplasmic reticulum) and mapped the ryanodine receptor gene (RYR) to region q13.1 of human chromosome 19 (ref. 14), in close proximity to genetic markers that have been shown to map near the MH susceptibility locus in humans and the halothane-sensitive gene in pigs. As a more definitive test of whether the RYR gene is a candidate gene for the human MH phenotype, we have carried out a linkage study with MH families to determine whether the MH phenotype segregates with chromosome 19q markers, including markers in the RYR gene. Co-segregation of MH with RYR markers, resulting in a lod score of 4.20 at a linkage distance of zero centimorgans, indicates that MH is likely to be caused by mutations in the RYR gene.

Animals↗