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D Anderson

Publications and source records attributed to D Anderson.

At least 433 records · Page 24Linked to original sources
PubMed1989

Cleaving the prohead RNA of bacteriophage phi 29 alters the in vitro packaging of restriction fragments of DNA-gp3.

In vitro packaging of restriction fragments of the bacteriophage phi 29 DNA-gp3 (DNA-gene product 3 complex) in the defined system was dependent on prohead RNA. Truncated prohead RNAs were obtained by in situ RNase A digestion, isolated and sequenced. Proheads having the intact 174 base RNA were compared to proheads having RNAs of 120, 95, 71, 69 or 54 bases for the capacity to package the DNA-gp3 left and right ends and internal (non-end) fragments generated by the restriction enzymes EcoRI, HpaI and BstNI. Proheads with the 174 or 120 base RNAs packaged both left and right ends; internal fragments were packaged more efficiently by proheads with the 120 base RNA. Proheads with the 95 base RNA packaged DNA-gp3 left ends and internal fragments efficiently, but lost the capacity to package right ends. Only internal fragments were packaged by proheads with the 71 base RNA, and proheads having 69 or 54 base RNAs were inactive. RNA-free proheads were effectively reconstituted with purified 174 and 120 base RNAs to produce particles similar in biological activity to the proheads from which the RNAs were isolated. The 95 base RNA was the smallest RNA of the group that could reconstitute the prohead and direct fragment packaging, although packaging was inefficient. Alteration of the specificity of DNA fragment packaging with truncated prohead RNAs has delineated RNA domains that function in DNA-gp3 recognition and prohead binding.

Bacteriophage lambda↗
PubMed1989

Prohead RNA of bacteriophage phi 29: size, stoichiometry and biological activity.

We previously demonstrated (Guo et al., 1987. Nucl. Acids Res. 15, 7081-7090) that purified proheads of bacteriophage phi 29 contain an RNA of 120 bases which is essential for DNA packaging. Here we report that this RNA exists primarily as a polymer of ca. 174 residues in phage-infected cells and that ca. 54 bases are cleaved from its 3'-terminus by adventitious nucleases during the purification of proheads. The long and short forms of the RNA had similar activity in in vitro DNA packaging and phage assembly. We report the sequence of the long form of the RNA and show that similar long and short forms can be isolated from the proheads of the phi 29 relatives phi 21, phi 15 and SF5. The concentration dependence in the reconstitution of RNA-free proheads suggests that one copy of the RNA is sufficient to restore DNA packaging activity to RNA-free proheads. However, quantitative measurements indicate that 5 to 6 copies of the RNA are present on proheads isolated from phage-infected cells.

Bacillus subtilis↗
PubMed1989

Heterogeneity in human interleukin-3 receptors. A subclass that binds human granulocyte/macrophage colony stimulating factor.

125I-Labeled recombinant human interleukin-3 (IL-3) was used to study the characteristics and distribution of receptors for IL-3 on human cells. Receptors were found on primary monocytes, on some strains of KG-1 cells, and on pre-B cell lines. Binding was rapid at 37 degrees C, while requiring several hours to reach equilibrium at 4 degrees C. Equilibrium binding studies indicated that IL-3 bound to a single class of high affinity receptor (less than 500 receptors/cell) with a Ka of approximately 1 x 10(10) M-1. Inhibition studies revealed that human granulocyte/macrophage colony stimulating factor partially inhibited the binding of 125I-IL-3 to human monocytes but not JM-1 cells. Additional analysis showed that on KG-1 cells, both IL-3 and GM-CSF partially competed specific binding of heterologous radiolabeled ligand, with approximately equivalent capacities. This competition occurred at both 37 and 4 degrees C. These results suggest heterogeneity in the binding sites for IL-3 and GM-CSF in which a subset of receptors binds only IL-3, a subset only GM-CSF, and another subset can bind both, all with high affinity. Additional heterogeneity was suggested by equilibrium binding of 125I-IL-3 to KG-1 cells which revealed a biphasic Scatchard plot containing a low affinity component not observed on monocytes and JM-1 cells.

Binding, Competitive↗
PubMed1989

Recombinant interleukin 7, pre-B cell growth factor, has costimulatory activity on purified mature T cells.

The activation of highly purified murine peripheral T cells in vitro by Con A is dependent on a co-stimulatory signal that is not IL-1 or IL-2. Previous evidence has demonstrated that the recently defined lymphokine IL-6 could provide costimulatory activity for purified T cells cultured with Con A. In this report we demonstrate that IL-7 also has potent co-stimulatory activity for purified murine T cells, as well as its previously described ability to support the growth of pre-B cells in Witte-Whitlock cultures. When rIL-7 was added to cultures of purified T cells together with Con A, it induced the expression of IL-2 receptors, IL-2 production, and consequently proliferation. In addition, IL-7 exhibited the same magnitude of activity in this assay as IL-6. Also, anti-IL-6 antibody which inhibited the IL-6-induced response had no effect on the IL-7 response. Thus, IL-7 does not act by inducing IL-6. These results demonstrate that IL-7, a potent growth stimulus for pre-B cells, also has a role in T cell activation.

Animals↗
PubMed1989

The contributions of self-defeating philosophies, perceived helplessness, and repression to anxiety among psychiatric patients.

Four of the most influential psychological explanations for the development of anxiety attribute it to (1) repressed awareness of undesirable emotions; (2) the emergence of unacceptable feelings from the unconscious; (3) adherence to irrational, self-defeating philosophies; and (4) perceived helplessness/lack of control over one's affairs. To test these theories, the authors administered the Trait Anxiety, Denial, Irrational Beliefs, and Locus of Control scales to 190 psychiatric inpatients. Appropriate zero-order, attenuation-corrected, multiple, and partial correlations were run. Denial was correlated negatively with Trait Anxiety; this is consistent with the view that awareness of unpleasant emotions generates anxiety, but does not support the claim that it is the result of repression. The correlations of Trait Anxiety with the Irrational Beliefs scale were substantial. However, its relationships with Locus of Control were limited and nonsignificant after the effects of the Denial and Irrational Beliefs scales were removed statistically. The findings lend support to the positions that anxiety results from self-defeating philosophies and/or the emergence of unpleasant thoughts about oneself, but give only modest support to the "perceived helplessness" hypothesis and seem to contradict the "excessive repression" explanation.

Adjustment Disorders↗
PubMed1989

Laparoscopy, ultrasound and computed tomography in cancer of the oesophagus and gastric cardia: a prospective comparison for detecting intra-abdominal metastases.

We have evaluated the sensitivity, specificity and accuracy of laparoscopy under general anaesthesia, ultrasound and computed tomography (CT) in detecting intra-abdominal metastases in 90 consecutive patients with carcinoma of the oesophagus or cardia. Metastases were histologically confirmed as hepatic in 25 patients, nodal in 35 and peritoneal in nine. All investigations had high specificity (86-100 per cent) for each type of metastasis. Laparoscopy was found to be significantly more sensitive (P less than 0.01; P less than 0.02) and more accurate (P less than 0.01; P less than 0.01) than either ultrasound or CT, respectively, with regard to hepatic status. Although laparoscopy performed best with regard to nodal metastases, this reached statistical significance only when sensitivity of ultrasound was compared (P less than 0.01). Neither ultrasound nor CT detected any peritoneal metastases, although laparoscopy detected eight out of nine, giving a sensitivity of 89 per cent and an accuracy of 98 per cent. There was no morbidity or mortality associated with laparoscopy, which offers a safe, reliable method of determining intra-abdominal status and may obviate the need for surgery in some patients with malignant dysphagia.

Abdominal Neoplasms↗
PubMed1989

Phenotypic and functional differences in NK and LAK cells in the peripheral blood of sooty mangabeys and rhesus macaques.

Greater than 75% of the sooty mangabey monkeys at the Yerkes Regional Primate Research Center are naturally infected with SIV without any apparent clinical symptomology. On the other hand, experimental infection of rhesus macaques with SIV results in a clinical syndrome similar to human AIDS. These differences with regard to SIV infection prompted us to examine the natural immunosurveillance system of peripheral blood mononuclear cells (PBMC) from SIV-infected and uninfected monkeys of these two species. Phenotypic and functional studies of precursor and effector NK and LAK cells in the PBMC from these two species were carried out using monoclonal reagents, flow microfluorometry (FMF), and the standard in vitro 51Cr release assay against prototype K562 (NK sensitive) and RAJI (NK resistant, LAK susceptible) target cell lines. Data indicate that both NK and LAK cell activities in the PBMC of sooty mangabeys were significantly (P less than 0.01) greater than those in rhesus macaques. The predominant NK effector cells and LAK cell precursors were shown to be Leu 19-CD8+ in the PBMC of sooty mangabeys and Leu19+ CD8- in the PBMC of rhesus macaques as determined by panning depletion techniques and FMF analysis. On the other hand, the predominant LAK effector cells were found to be dual marked Leu 19+ CD8+ in rhesus macaques and Leu 19- CD8+ in sooty mangabeys. These qualitative and quantitative differences were not due to SIV infection of these two species since PBMC from both SIV-seropositive and virus-positive and SIV-sero-negative and virus-negative monkeys gave similar results. Moreover, of importance is the finding that the functional NK and LAK precursor cells are CD8+ and CD8- in sooty mangabeys and rhesus macaques, respectively. These data may have implications for the natural SIV/SMM virus-positive asymptomatic state of sooty mangabeys and may provide useful tools for tracing the ontogeny and lineage derivation of NK and LAK cells.

Animals↗
PubMed1989

Microsome-mediated clastogenicity of butylated hydroxyanisole (BHA) in cultured Chinese hamster ovary cells: the possible role of reactive oxygen species.

Butylated hydroxyanisole (BHA) was found to induce chromosome aberrations in Chinese hamster ovary (CHO) cells in the presence of Aroclor-induced rat-liver S9. The effects were more marked when washed microsomes were employed and chromosome damage was considerably reduced in the presence of catalase, suggesting that hydrogen peroxide was involved. Stimulation of H2O2 production by BHA in S9 or microsome incubation mixtures was demonstrated using the catalase-mediated production of formaldehyde from methanol. One of the major microsomal metabolites of BHA, tert.-butyl hydroquinone (t-BHQ), which autoxidises in solution producing H2O2 also induced extensive catalase-sensitive chromosome damage in the absence of metabolic activation. These observations suggest that extracellular generation of reactive oxygen species may be implicated in the mechanism of BHA clastogenicity in vitro. However, chromosome damage was not completely abolished by catalase and the end product of t-BHQ oxidation, tert.-butyl quinone, was also weakly clastogenic, suggesting that intracellular effects of quinone metabolites may also be involved in the clastogenicity of BHA.

Animals↗
PubMed1989

The protective effects of L-ascorbic acid and DL-alpha-tocopherol on cultured rat embryos treated with xanthine/xanthine oxidase.

Abnormalities of the neural suture were observed in cultured rat embryos exposed to oxygen radicals generated by xanthine and xanthine oxidase. The distribution of the severity of these abnormalities was altered by the addition of L-ascorbic acid (AA) or DL-alpha-tocopherol (AT). The antioxidant effect of AA and AT were probably responsible for the protection of the embryos from the damaging effects of oxygen radicals.

Animals↗
PubMed1989

Sister-chromatid exchanges in 52 Korean women living in the vicinity of an industrial complex.

Sister-chromatid exchanges (SCE) were examined in the peripheral lymphocytes of 52 Korean women living in the vicinity of an industrial complex. They were generally non-smokers ranging from 22 to 56 years of age. The mean SCE score of the volunteers was 6.01 +/- 0.15 (SE). Only coffee intake produced a significant increase of SCE by comparison with the mean SCE for those that did not take coffee. Other parameters, including alcohol intake, working in industry and the presence of hepatitis B surface antigen (HBsAg), did not produce an increase in SCE. There was no effect on SCE due to age.

Adult↗
PubMed1989

Developmental defects of the tympanic plate: case reports and review of the literature.

A complete otoscopic examination should be performed in all patients seeking treatment of temporomandibular disorders. The presence of a bulge in the external auditory meatus that disappears with mouth opening may suggest the persistence of the foramen of Huschke. The clinician should rule out the presence or history of infection, trauma, or neoplasm before ascribing the etiology of a defect to a developmental aberration.

Aged↗
PubMed1989

Thymidine kinase obliteration: creation of transgenic mice with controlled immune deficiency.

The cell-specific expression of herpes simplex virus 1 thymidine kinase (HSV-1-tk) has provided a simple and highly efficient technique to achieve conditional ablation of targeted cell types in transgenic mice. The ablation is induced by treating transgenic animals expressing HSV-1-tk with the antiherpetic drug ganciclovir. In lymphoid tissues of mice expressing HSV-1-tk from an immunoglobulin promoter, administration of ganciclovir leads to massive destruction of B- and T-cell lineages. Tissues not expressing HSV-1-tk are insensitive to drug treatment. After depletion of greater than 99% of total thymocytes, a number of progenitor cells remain that are able to repopulate all T-cell lineages within 7 days. The ability to control and direct ablation allows for creation of conditional mutant phenotypes at precise periods of development. This technique also provides a potential means to enrich stem cell populations as well as permitting the creation of animal models for particular pathological conditions.

Acyclovir↗
PubMed1989

A multicentre randomized trial comparing delivery with a silicone rubber cup and rigid metal vacuum extractor cups.

A total of 258 women requiring assisted delivery where vacuum extraction was thought to be suitable were randomly allocated to delivery with a new silicone rubber cup or metal vacuum extractor cups. There was a tendency for the silicone rubber cup to effect delivery more quickly and to cause less scalp trauma, but to fail to effect delivery on more occasions than metal cups. However, none of these differences was statistically significant. There were no statistically significant differences in the rates of birth canal trauma, maternal blood loss, or neonatal jaundice. The silicone rubber cup produced a cosmetically more acceptable chignon than the metal cups. The introduction of vacuum extractors with silicone rubber cups into obstetric units should be encouraged.

Double-Blind Method↗
PubMed1989

Cooperative binding of Agrobacterium tumefaciens VirE2 protein to single-stranded DNA.

The VirE2 protein of Agrobacterium tumefaciens Ti plasmid pTiA6 is a single-stranded-DNA-binding protein. Density gradient centrifugation studies showed that it exists as a tetramer in solution. Monomeric VirE2 active in DNA binding could also be obtained by using a different protein isolation procedure. VirE2 was found to be thermolabile; brief incubation at 37 degrees C abolished its DNA-binding activity. It was insensitive to the sulfhydryl-specific reagent N-ethylmaleimide. Removal of the carboxy-terminal 37 residues of the 533-residue VirE2 polypeptide led to complete loss of DNA-binding activity; however, chimeric fusion proteins containing up to 125 residues of the VirE2 C terminus were inactive in DNA binding. In nuclease protection studies, VirE2 protected single-stranded DNA against degradation by DNase I. Analysis of the DNA-VirE2 complex by electron microscopy demonstrated that VirE2 coats a single-stranded DNA molecule and that the binding of VirE2 to its substrate is cooperative.

Bacterial Proteins↗
PubMed1989

Immunocytochemical studies of gastric H+,K+-ATPase in the developing rat.

The appearance of the enzyme H+,K+-ATPase was studied in the gastric mucosa of rats during the perinatal period. By means of monoclonal antibodies against the enzyme, immunoreactivity was regularly detected in parietal cells 1 day before birth. The intensity of the staining and the frequency of stained cells increased up to 10-12 days after birth, when adult levels were approached. Electron microscopy showed that the initial staining occurred at the apical surface of the parietal cells, with only faint or no staining at the secretory canaliculi. From 5 days after birth immunoreactivity was observed also at the tubulovesicular membranes.

Adenosine Triphosphatases↗