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D E Ott

Publications and source records attributed to D E Ott.

At least 37 records · Page 2Linked to original sources
PubMed1995

Analysis and localization of cyclophilin A found in the virions of human immunodeficiency virus type 1 MN strain.

Previous reports have shown that cyclophilin A (CyPA) is found to be specifically associated with human immunodeficiency virus type-1 (HIV-1) virions and is required for infectivity (Franke et al. Nature 372:359; Thali et al. Nature 372:363). We have examined CyPA associated with HIV-1MN virions. Virions from infected human lymphoid cells were analyzed by high-pressure liquid chromatography (HPLC), protein sequence, and immunoblot analysis. At least three forms of CyPA were found: an unmodified form, an N-terminally modified form, and an N-terminally modified form that migrates as a larger isoform on a reducing-SDS polyacrylamide gel. Using a protease digestion procedure, CyPA that is associated with virions was found to be located inside the viral membrane. Similar examination of SIVMne produced by HUT-78 human T cells did not detect specific incorporation of CyPA into SIV virions. Our results are consistent with the role of CyPA acting early in the infectious process of HIV-1.

Amino Acid Isomerases↗
PubMed1995

The majority of cells are superinfected in a cloned cell line that produces high levels of human immunodeficiency virus type 1 strain MN.

We have isolated seven single-cell clones from an H9 culture infected with human immunodeficiency virus type 1 strain MN so that a stable producer of virus could be obtained. DNAs from these clones were examined by Southern blot analysis and found to contain between one and four proviruses per clone. One of these cell lines, Clone 4, produced high levels of replication-competent virus and contained two proviruses. Southern blot analysis of DNAs from Clone 4 revealed that, after extended culture, some of the cells had acquired additional proviruses, presumably by superinfection. Analysis of Clone 4 single-cell subclones isolated from a late-passage culture found that 14 out of 20 (70%) subclones were reinfected and that 8 out of 20 (40%) were reinfected more than once. Fluorescence-activated cell sorter analysis showed that surface CD4 levels on Clone 4 cells were appropriately down-regulated. Our results indicate that while there is significant interference to superinfection in the Clone 4 culture, it is not absolute and that superinfected cells accumulate in the culture over time in the presence of high virus exposure and extensive cell-to-cell contact. Given our data, it seems likely that superinfection can occur in vivo within the lymphoid reservoirs that harbor human immunodeficiency virus type 1 during the clinically latent period and may contribute to disease progression.

CD4 Antigens↗
PubMed1994

10A1 MuLV induces a murine leukemia that expresses hematopoietic stem cell markers by a mechanism that includes fli-1 integration.

The 10A1 murine leukemia virus induces tumors that lack lineage-specific markers found on myeloid, T-cell, and B-cell lineages. Either erythroid or multipotent stem cells can have this phenotype; therefore we have used fluorescence-activated cell sorter analysis with either multipotent stem cell markers or markers found on lineage-restricted precursors to differentiate between these two possibilities. The results showed that tumors induced by 10A1 expressed multipotent stem cell markers as well as some lineage-restricted precursor markers. To further study the tumor phenotype, we analyzed total RNAs from 10A1-induced tumors by Northern blotting for c-kit, erythropoietin receptor, and T-cell gamma receptor mRNAs. Most of the tumors contained these mRNAs, which are characteristic of early hematopoietic cells. These results are consistent with the hypothesis that 10A1-induced tumor cells are early multipotent hematopoietic stem cells. Southern blot analysis revealed that 14 of 14 10A1-induced tumor cell DNAs examined contained MuLV integrations into the fli-1 gene. The results strongly suggested that promoter insertion into fli-1 is required for tumor formation.

Animals↗
PubMed1992

Phenotypes of murine leukemia virus-induced tumors: influence of 3' viral coding sequences.

Murine leukemia viruses (MuLVs) induce leukemias and lymphomas in mice. We have used fluorescence-activated cell sorter analysis to determine the hematopoietic phenotypes of tumor cells induced by a number of MuLVs. Tumor cells induced by ecotropic Moloney, amphotropic 4070A, and 10A1 MuLVs and by two chimeric MuLVs, Mo(4070A) and Mo(10A1), were examined with antibodies to 13 lineage-specific cell surface markers found on myeloid cell, T-cell, and B-cell lineages. The chimeric Mo(4070A) and Mo(10A1) MuLVs, consisting of Moloney MuLV with the carboxy half of the Pol region and nearly all of the Env region of 4070A and 10A1, respectively, were constructed to examine the possible influence of these sequences on Moloney MuLV-induced tumor cell phenotypes. In some instances, these phenotypic analyses were supplemented by Southern blot analysis for lymphoid cell-specific genomic DNA rearrangements at the immunoglobulin heavy-chain, the T-cell receptor gamma, and the T-cell receptor beta loci. The results of our analysis showed that Moloney MuLV, 4070A, Mo(4070A), and Mo(10A1) induced mostly T-cell tumors. Moloney MuLV and Mo(4070A) induced a wide variety of T-cell phenotypes, ranging from immature to mature phenotypes, while 4070A induced mostly prothymocyte and double-negative (CD4- CD8-) T-cell tumors. The tumor phenotypes obtained with 10A1 and Mo(10A1) were each less variable than those obtained with the other MuLVs tested. 10A1 uniformly induced a tumor consisting of lineage marker-negative cells that lack lymphoid cell-specific DNA rearrangements and histologically appear to be early undifferentiated erythroid cell-like precursors. The Mo(10A1) chimera consistently induced an intermediate T-cell tumor. The chimeric constructions demonstrated that while 4070A 3' pol and env sequences apparently did not influence the observed tumor cell phenotypes, the 10A1 half of pol and env had a strong effect on the phenotypes induced by Mo(10A1) that resulted in a phenotypic consistency not seen with other viruses. This result implicates 10A1 env in an active role in the tumorigenic process.

Animals↗
PubMed1991

Laparoscopic hypothermia.

Operative laparoscopy is experiencing an increase in its use and indications. This expansion exposes patients to increased operating time, larger volumes of carbon dioxide for maintenance of a pneumoperitoneum, and higher gas flow rates for intraperitoneal delivery. Patients with medical complications, advancing age, and potentially contaminated procedures are now considered acceptable candidates for operative endoscopic techniques via laparoscopy. A previously observed but unquantified amount of hypothermia was measured and evaluated by changes in core temperature after known quantities of carbon dioxide were delivered intra-abdominally over measured periods of time and with controlled flow rates. A decrease of 0.3 degrees C in the core temperature was observed for each 50 L of carbon dioxide delivered.

Blood Gas Analysis↗
PubMed1991

Correction of laparoscopic insufflation hypothermia.

Because of the iatrogenic hypothermic stress of a 0.3 degrees C loss created by carbon dioxide pneumoperitoneum insufflation at laparoscopy, it is important to reduce this danger to a minimum. The risk is diminished by increasing the temperature of the delivered carbon dioxide gas to 30.0-30.5 degrees C. This was demonstrated by evaluating 20 patients undergoing laparoscopies with unheated carbon dioxide pneumoperitoneum and 20 with heated carbon dioxide pneumoperitoneum. All procedures were performed without the use of laser or cautery. The group receiving the heated gas had lower and more stable thermal losses. Warming of the carbon dioxide prior to abdominal delivery is recommended to counteract hypothermia.

Abdomen↗
PubMed1989

Molecular requirements for immunoglobulin heavy chain constant region gene switch-recombination revealed with switch-substrate retroviruses.

We have employed a retroviral vector, ZN(Smu/S gamma 2b)tk1, as a means of introducing immunoglobulin heavy chain (IgH) switch (S) region sequences into B cell lines to directly measure their switch-recombinase activities. In an earlier study, we demonstrated that retrovector Smu-S gamma 2b recombination events occurred in two thymidine kinase (tk)-negative murine pre-B cell lines (18-8 and 38B9) upon selection in bromodeoxyuridine (BUdR) media for the loss of an Htk gene inserted in between the vector's Smu and S gamma 2b sequences. Here we have used this assay system to show that the 300-18 murine pre-B cell line possesses a very high level of switch-recombinase activity (greater than 1 event in 2500 cells/generation) while a terminally differentiated, antibody-secreting hybridoma line (A39R 1.1) has no detectable recombinase activity. Both S mu and S gamma 2b segments are required for switch region-mediated deletions. Retrovectors harboring only an Smu segment or an Smu segment and a portion of the murine c-myc gene in place of S gamma 2b sequences were both non-recombinagenic in this assay system. Nucleotide sequence analysis of six retrovector S segment recombinants, recovered from ZN(Smu/S gamma 2b) tk1-infected 18-8 and 39B9 pre-B lines, did not reveal homology at their sites of recombination. We conclude that: (1) S segment repetitive sequences play an essential but indirect role in IgCH gene switch-recombination, which occurs by an illegitimate, non-homologous mechanism; (2) the c-myc gene is not a significant target for switch-recombination; and (3) since endogenous Smu and S gamma 2b rearrangements were not observed in populations and clones of pre-B cells expressing a high level of switch-recombinase activity, multiple factors (presumably contributed in part by the degree of S segment accessibility) in addition to S recombinase activity are required for CH class switching.

Animals↗
PubMed1987

Immunoglobulin heavy chain switch region recombination within a retroviral vector in murine pre-B cells.

We have employed a retroviral vector, ZN(Smu/S gamma 2b)tk1, as a substrate for detecting the presence of immunoglobulin heavy chain constant region (CH) gene switch (S) recombination activity in murine pre-B cells. ZN(Smu/S gamma 2b)tk1 contains a neomycin (neo) resistance gene in addition to the herpes simplex virus thymidine kinase (Htk) gene which is positioned between murine Smu and S gamma 2b sequences. Stable acquisition of the ZN(Smu/S gamma 2b)tk1 vector was selected in G-418 and switch region recombination within these proviruses was selected by resistance to the drug bromodeoxyuridine (BUdR). Fluctuation analyses of ZN(Smu/S gamma 2b)tk1 infected 18-8tk- and 38B9tk- pre-B lines revealed Htk gene inactivations with apparent frequencies of 5 X 10(-5) and 1 X 10(-5) events/cell/generation, respectively, while G-418 resistant Ltk- fibroblasts lost the HTK phenotype at an apparent rate of 4 X 10(-8). Southern blot analysis demonstrated that switch recombination caused the deletion of the Htk gene in all pre-B clones examined while the loss of Htk in Ltk- clones was not mediated by S region recombination. In 21 out of 24 pre-B clones, the recombinations involved the tandemly repetitive portions of the Smu and S gamma 2b sequences. These results demonstrate that the CH gene S region segments inserted into ZN(Smu/S gamma 2b)tk1 are sufficient for B-cell-specific recombination/deletion within the S region tandem repeats.

Animals↗
PubMed1983

Colorimetric method for field-screening above-tolerance parathion residues on and in citrus fruits.

A colorimetric technique has been developed which is suitable for use as a field-screening method for detecting above-tolerance levels of parathion on and in citrus fruits. By using this method, a grower should be able to postpone harvesting a crop until parathion residues are below tolerance level, so that the crop is safe to market. The method depends on the reaction of parathion with 4-(p-nitrobenzyl)-pyridine. Parathion is extracted by mixing chopped citrus rind with acetone in a hand-operated homogenizer. The extract is partially cleaned by a partitioning step before final cleanup with a Sep-Pak Florisil cartridge. The colored reaction solution is read at 560 nm by using a portable, rechargeable spectrophotometer. A single test can be completed in about 75 min; the average time per test when several are conducted sequentially is considerably shorter. The analytical system responds readily to less than 5 ppm parathion on or in 1 g navel orange rind, which corresponds to less than 1 ppm in the whole fruit. The present U.S. tolerance for parathion on or in citrus is 1 ppm on a whole fruit basis. Preliminary work indicates that the method should also be suitable for apples.

Citrus↗
PubMed1982

Field screening method for above-tolerance residues of dithiocarbamate fungicides.

A field screening method has been developed for detecting above-tolerance residues of dithiocarbamate (DTC) fungicides on fruits and vegetables. A harvested crop might be condemned as unfit for market if above-tolerance DTC residues are present; however, by using this screening method, a grower might be able to postpone harvesting a crop until the screening test indicates that residues have dissipated below the tolerance level. The method depends on carbon disulfide generated from DTC fungicides at an elevated temperature into the headspace gas above the contents of a septum-sealed reaction flask, with hydrochloric acid and stannous chloride present. The syringe-withdrawn, headspace carbon disulfide then reacts with the appropriate chromophore reagent already in the syringe. The lower limit of detectability is about 2 ppm DTC fungicide from 30 g chopped crop. A single test can be completed in about 90 min; the average time per test when several are conducted sequentially is considerably shorter.

Fruit↗
PubMed1978

Evaluation of amperometric detector for liquid chromatographic determination of 2-phenylphenol residues in orange rind.

A modular component liquid chromatograph has been assembled which has on-stream ultraviolet (UV) and amperometric detectors connected to a dual pen recorder. In this method, the commonly used UV detection technique provides a reference for direct comparisons of results from the amperometric detector. The system has been evaluated and applied to the determination of 2-phenylphenol (2PP) fortified in orange rind. The method is not tedious; before liquid chromatographic analysis, the sample is extracted with methylene chloride and cleaned up on a Florisil column. The method is sensitive to less than 1 ppm 2PP fortified in orange rind; there are no electrically oxidizable interference, from control samples, in the chromatographic region of 2PP. Some background interference does appear from the same samples on the UV chromatogram. Thus, amperometric detection is more specific than UV detection for this application.

Biphenyl Compounds↗
PubMed1977

Liquid chromatographic determination of azinphos methyl oxon in foliar dislodgeable residues and in soil surface dusts from an azinphos methyl-treated orange grove.

Specific parts of the worker environment in an orange grove that had been sprayed with azinphos methyl formulation were tested for azinphos methyl oxon. Extracts of soil surface dusts and dislodgeable residues from orange leaf surfaces were prepared and analyzed by liquid chromatographic procedures incorporating an ultraviolet absorption detector primarily for quantitation and an on-stream chemical reaction detector primarily for confirmation. Azinphos methyl oxon residues were found in both types of samples collected 3-59 days after spraying. Foliar dislodgeable residues of the oxon ranged from a high of 0.057 microgram/sq cm of leaf surface on the 17th day to a low of 0.014 microgram/sq cm on the 59th day for trees treated with a low-volume spray. The corresponding range in soil dust samples was 5.2 microgram/g (ppm) of dust on the 10th day to 1.4 microgram/g on the 59th day. Values were 9.7 and 2.7 microgram/g, respectively, for samples from under trees similarly treated with a high-volume spray.

Azinphosmethyl↗
PubMed1975

Automated fluorometric determination of thiabendazole.

An automated fluorometric method is presented for the determination of thiabendazole (2-(4'-thiazolyl)benzimidazole) in 0.1N HCl solutions. Test solutions of at least 1.1 ml starting volume are sampled and pumped successively at the rate of 60/hr into a fluorometer equipped with a simple flowcell. The minimum level of detection of the fungicide is about 0.05 mu-g/ml.

Autoanalysis↗