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Biomedical subjects

L Phillips

Publications and source records attributed to L Phillips.

At least 109 records · Page 6Linked to original sources
PubMed1995

Chattanooga Creek: case study of the public health nursing role in environmental health.

Public health nurses have two primary roles in protecting their communities from hazardous substances: community assessment and health education. Developing assessment skills in environmental health enables public health nurses to collaborate with other federal, state, and county agencies in identifying public health hazards and making health-based recommendations at hazardous waste sites needing remedial or removal interventions. Community health education empowers communities to minimize their exposure to hazardous wastes in their environment. Methods for community environmental health assessment and interventions are demonstrated in this article by activities conducted at the Chattanooga Creek site in Chattanooga, Tennessee. A thorough assessment and collaborative approach between government agencies, local health professionals, and community members resulted in a successful community health education program and this site's placement on the National Priorities List.

Environmental Health↗
PubMed1995

Isolation of a highly cytopathic lentivirus from a nondomestic cat.

A feline immunodeficiency virus-like virus (FIV-Oma) isolated from a Pallas' cat (Otocolobus manul) is highly cytopathic in CrFK cells, in contrast to the chronic, noncytolytic infection established by an FIV isolate from a domestic cat (FIV-Fca). The virions have typical lentivirus morphology, density, and magnesium-dependent reverse transcriptase activity. The major core protein is antigenically cross-reactive with that of FIV-Fca; however, FIV-Oma transcripts do not cross-hybridize with FIV-Fca. A conserved region of the FIV-Oma pol gene has 76 to 80% nucleic acid identify with the corresponding pol regions of other feline lentiviruses and 64 to 69% identity with those of human, ovine, and equine lentiviruses.

Animals↗
PubMed1994

5-Aminoimidazole-4-carboxamide ribotide transformylase-IMP cyclohydrolase from human CCRF-CEM leukemia cells: purification, pH dependence, and inhibitors.

The bifunctional enzyme 5-aminoimidazole-4-carboxamide ribotide (AICAR) transformylase-IMP cyclohydrolase has been purified 780-fold to apparent homogeneity from human CCRF-CEM leukemia cells, completed with chromatography on Affi-Gel Blue followed by AICAR-Sepharose 4B. Using a sensitive radioassay, IMP cyclohydrolase has a Ks value for 5-formamidoimidazole-4-carboxamide ribotide (FAICAR) at pH 7.4 of 0.87 +/- 0.11 microM. The following purine nucleotide derivatives were potent competitive inhibitors of IMP cyclohydrolase: 2-mercaptoinosine 5'-monophosphate (Ki = 0.094 +/- 0.024 microM), xanthosine 5'-monophosphate (Ki = 0.12 +/- 0.01 microM), 2-fluoroadenine arabinoside 5'-monophosphate (Ki = 0.16 +/- 0.02 microM), 6-mercaptopurine riboside 5'-monophosphate (Ki = 0.20 +/- 0.02 microM), adenosine N1-oxide 5'-monophosphate (Ki = 0.28 +/- 0.03 microM), and N6-(carboxymethyl)adenosine 5'-monophosphate (Ki = 1.7 +/- 0.42 microM). The pH dependencies of Vmax and Vmax/Ks values for IMP cyclohydrolase are consistent with a single ionizable amino acid residue (pKa = 7.57 +/- 0.09) of the enzyme which must be unprotonated for catalysis to occur and a residue (pKa = 7.57 +/- 0.14) which must be unprotonated for FAICAR to bind. The pKa values of 5.81 +/- 0.03 and 9.41 +/- 0.04 determined for FAICAR indicate that ionization of the substrate does not contribute significantly to the pH effects observed. Chemical modification of IMP cyclohydrolase provides evidence for arginine and cysteine residues at the active site, and roles for these residues in the mechanism of catalysis are proposed.

Acyltransferases↗
PubMed1994

Development and validation of an air-to-beef food chain model for dioxin-like compounds.

A model for predicting concentrations of dioxin-like compounds in beef is developed and tested. The key premise of the model is that concentrations of these compounds in air are the source term, or starting point, for estimating beef concentrations. Vapor-phase concentrations transfer to vegetations that cattle consume, and particle-bound concentrations deposit onto soils and these vegetations as well. Congener-specific bioconcentration parameters, coupled with assumptions on cattle diet, transform soil and vegetative concentrations into beef fat concentrations. The premise of the validation exercise is that a profile of typical air concentrations of dioxin-like compounds in a United States rural environment is an appropriate observed independent data set, and that a representative profile of United States beef concentrations of dioxin-like compounds is an appropriate observed dependent result. These data were developed for the validation exercise. An observed concentration of dioxin toxic equivalents in whole beef of 0.48 ng/kg is compared with a predicted 0.36 ng/kg. Principal uncertainties in the approach are identified and discussed. A major finding of this exercise was that vapor phase transfers of dioxin-like compounds to vegetations that cattle consume dominate the estimation of final beef concentrations: over 80% of the modeled beef concentration was attributed to such transfers.

Air Pollutants↗
PubMed1994

Interleukin-1 beta induces differential adhesiveness on human endothelial cell surfaces.

The adhesive strength between HL-60 and endothelial cells activated with IL-1 beta was investigated according to the region (area) on the endothelial cell surface where the HL-60 cell was attached (nuclear, junctional, or cytoplasmic). Using a micropipette single-cell manipulation system, we demonstrated that the increase of adhesive force was due to the activation of the endothelial cell with IL-1 beta and a function of the region of the endothelial cell. The increase in adhesion strength due to the increased expression of E-Selectin on the endothelial cell was studied by the addition of monoclonal antibodies against E-Selectin, ICAM-1, VCAM, and PECAM-1. Our findings suggest that the greatest adhesive strength was seen in the junctional region where the antibodies could not block the adhesion. However, the contribution of E-Selectin was significant in the nuclear region.

Antibodies, Monoclonal↗
PubMed1994

Cytotoxic effects of inhibitors of de novo pyrimidine biosynthesis upon Plasmodium falciparum.

The malarial parasite Plasmodium falciparum can only synthesize pyrimidine nucleotides via the de novo pathway which is therefore a suitable target for development of antimalarial drugs. New assay procedures have been developed using high-pressure liquid chromatography (HPLC) which enable concurrent measurement of pyrimidine intermediates in malaria. Synchronized parasites growing in erythrocytes were pulse-labeled with [14C]bicarbonate at 6-h intervals around the 48-h asexual life cycle. Analysis of malarial extracts by HPLC showed tht incorporation of [14C]bicarbonate into pyrimidine nucleotides was maximal during the transition from trophozoites to schizonts. The reaction, N-carbamyl-L-aspartate-->L-dihydroorotate (CA-asp-->DHO) catalyzed by malarial dihydroorotase is inhibited by L-6-thiodihydroorotate (TDHO) in vitro (Ki = 6.5 microM), and TDHO, as the free acid or methyl ester, induces a major accumulation of CA-asp in malaria. Atovaquone, a naphthoquinone, is a moderate inhibitor of dihydroorotate dehydrogenase in vitro (Ki = 27 microM) but induces major accumulations of CA-asp and DHO. Pyrazofurin induces accumulation of orotate and orotidine in malaria, consistent with inhibition of orotidine 5'-monophosphate (OMP) decarboxylase with subsequent dephosphorylation of the OMP accumulated. Although TDHO, atovaquone, and pyrazofurin arrest the growth of P. falciparum, only moderate decreases in UTP, CTP, and dTTP were observed. 5-Fluoroorotate also arrests the growth of P. falciparum with major accumulations of 5-fluorouridine mono-, di-, and triphosphates and the most significant inhibition of de novo biosynthesis of pyrimidine nucleotides.

Amides↗