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Biomedical subjects

C Campbell

Publications and source records attributed to C Campbell.

At least 109 records · Page 6Linked to original sources
PubMed1998

Optimizing the delivery of HIV counseling and testing services: the Uganda experience using rapid HIV antibody test algorithms.

The AIDS Information Center (AIC) was established in Kampala, Uganda in 1990 in response to increasing interest by members of the general public who wished to know their HIV serostatus. By 1996, >300,000 clients had been seen. HIV serologic testing was performed at a central laboratory and results reported back to AIC after 2 weeks. Approximately 25% of clients failed to learn their HIV serostatus as a result of failure to return or late arrival of results. To address these issues, AIC carried out an evaluation of 3 rapid HIV assays, Sero-Strip, SeroCard, and Capillus, against a standard criterion to identify a testing algorithm that could be used as an on-site confirmatory testing strategy. The study was carried out over a period of 5 working days and 325 clients were seen. An algorithm was identified, which gave no indeterminate results with unambiguously positive or negative specimens, which was 100% sensitive and specific, and which could be integrated with minimal disruption into existing counseling procedures. All clients left AIC knowing their HIV serostatus and having spent <2 hours at the Center. The results of this evaluation demonstrate that "same-day" results can be provided in counseling and testing settings without compromising the quality of counseling or the accuracy of HIV testing.

Algorithms↗
PubMed1998

Identification and characterization of the RAD51 gene from the ciliate Tetrahymena thermophila.

The RAD51 gene is a eukaryotic homolog of rec A, a critical component in homologous recombination and DNA repair pathways in Escherichia coli . We have cloned the RAD51 homolog from Tetrahymena thermophila , a ciliated protozoan. Tetrahymena thermophila RAD51 encodes a 36.3 kDa protein whose amino acid sequence is highly similar to representative Rad51 homologs from other eukaryotic taxa. Recombinant Rad51 protein was purified to near homogeneity following overproduction in a bacterial expression system. The purified protein binds to both single- and double-stranded DNA, possesses a DNA-dependent ATPase activity and promotes intermolecular ligation of linearized plasmid DNA. While steady-state levels of Rad51 mRNA are low in normally growing cells, treatment with UV light resulted in a >100-fold increase in mRNA levels. This increase in mRNA was time dependent, but relatively independent of UV dose over a range of 1400-5200 J/m2. Western blot analysis confirmed that Rad51 protein levels increase upon UV irradiation. Exposure to the alkylating agent methyl methane sulfonate also resulted in substantially elevated Rad51 protein levels in treated cells, with pronounced localization in the macronucleus. These data are consistent with the hypothesis that ciliates such as T.thermophila utilize a Rad51-dependent pathway to repair damaged DNA.

Amino Acid Sequence↗
PubMed1998

Fluid shear stress activation of egr-1 transcription in cultured human endothelial and epithelial cells is mediated via the extracellular signal-related kinase 1/2 mitogen-activated protein kinase pathway.

The primary response transcription factor, early growth response-1 (Egr-1), is rapidly activated by a variety of extracellular stimuli. Egr-1 binds to a sequence found in the promoters of genes involved in vascular injury, such as PDGF-A and tissue factor, and trans-activates their expression in endothelial cells in response to fluid shear stress. Here we show that egr-1 mRNA is increased after 30 min of flow in human aortic endothelial cell and HeLa cell cultures. Transient transfection of HeLa cells with reporter gene constructs driven by the murine or human egr-1 5' flanking sequence revealed a five- and ninefold induction, respectively, in transcriptional activity after exposure to a shear stress of 5 dynes/cm2 for 3 h. Deletion of sequences in the murine promoter containing two AP1 sites and an inhibitory Egr-1 binding sequence, did not reduce shear stress inducibility. However, progressive deletion of five serum response elements, reduced both the basal promoter activity and its capacity to be activated by shear stress. Further examination indicated that the three upstream serum response elements are predominantly responsible for shear stress activation of the egr-1 promoter. Treatment of cells with PD98059, a specific inhibitor of mitogen-activated protein kinase-1 inhibited shear stress activation of egr-1. We suggest that egr-1 activation by shear stress involves activation of Elk-1 but not c-jun activity. These data, which are consistent with previous findings for shear mediated signaling via the mitogen-activated protein kinase cascade, now implicate shear modulation of the Egr-1 transcription factor in this pathway.

Animals↗
PubMed1998

Long-chain alkenes of the haptophytes Isochrysis galbana and Emiliania huxleyi.

The major alkenes of the haptophytes Isochrysis galbana (strain CCAP 927/14) and Emiliania huxleyi (strains CCAP 920/2 and VAN 556) have been identified by nuclear magnetic resonance spectroscopy and by mass spectrometric analysis of their dimethyl disulfide adducts. The dominant alkene in I. galbana is (22Z)-1 ,22-hentriacontadiene, with 1,24-hentriacontadiene and 1,24-tritriacontadiene present in much lower abundance; (22Z)-1,22-hentriacontadiene also occurs in E. huxleyi (strain CCAP 920/2), together with (2Z,22Z)-2,22-hentriacontadliene (the major hydrocarbon) and (3Z,22Z)-3,22-hentriacontadiene. Minor abundances of 2,24-hentriacontadiene and 2,24-tritriacontadiene are also present in this strain. In contrast, the dominant alkene in E. huxleyi (strain VAN 556) is (15 E,22E)-1,16,23-heptatriacontatriene with the related alkatriene 1,15,22-octatriacontatriene also present and (22Z)-1,22-hentriacontadiene occurring as a minor component. From structural relationships (15E,22E)-1,15,22-heptatriacontatriene is proposed to derive from the same biosynthetic pathway as that of the characteristic C37 alkenones which occur in both E. huxleyi and I. galbana. The C31 and C33 dienes likely derive from chain extension and decarboxylation of (Z)-9-octadecenoic acid or (Z)-7-hexadecenoic acid, using a pathway analogous to that elucidated previously in the chlorophyte Botryococcus braunii. Therefore, long-chain dienes and trienes, which can co-occur in haptophytes, may have distinct biosynthetic pathways.

Alkenes↗