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Biomedical subjects

J L Kiel

Publications and source records attributed to J L Kiel.

At least 19 recordsLinked to original sources
PubMed1999

In vitro selection of DNA aptamers to anthrax spores with electrochemiluminescence detection.

Systematic evolution of ligands by exponential enrichment (SELEX) was used to select and PCR amplify DNA sequences (aptamers) capable of binding to and detecting nonpathogenic Sterne strain Bacillus anthracis spores. A simplified affinity separation approach was employed, in which autoclaved anthrax spores were used as the separation matrix. An aptamer-magnetic bead-electrochemiluminescence (AM-ECL) sandwich assay scheme was devised for detecting anthrax spores. Using a low SELEX DNA to spore ratio (154 ng DNA/10(6) spores), at least three distinct populations of single-stranded DNA aptamers, having varied affinities for anthrax spores, were noted by the AM-ECL assay. Results reflect detection of spore components with a dynamic range equivalent to < 10- > 6 x 10(6) anthrax spores. In the low DNA to spore ratio experiments, aptamers could be liberated from spore pellets by heating at 96 degrees C for 5 min after each round of SELEX. When a much higher DNA to spore ratio (10,256 ng DNA/10(6) spores) was used for SELEX development, a higher affinity set of aptamers was selected that could not be heat-eluted even at 99 degrees C for 5 min following round four of SELEX. However, high affinity spore surface bound aptamers were detectable via their 5'-biotinylated tails using labeled avidin and could be eluted in deionized water. Aptamers have potential for use as inexpensive, in vitro-generated receptors for biosensors in biological warfare detection and other areas.

Bacillus anthracis↗
PubMed1999

Luminescent radio frequency radiation dosimetry.

Thermoluminescent dosimetry has been the industry standard for ionizing radiation dosimetry because it is inexpensive, sensitive, and accurate. No such system exists for radio frequency radiation. This paper describes the state of the art of efforts toward developing such a system. Thermochemiluminescent (TCL) dosimetry, first reported in 1991, is a first step toward achieving this goal. However, it has had problems in the production of TCL materials and in conversion of the luminescent signal into specific absorption rate (SAR). The former problem has been solved by the development of a genetically engineered Escherichia coli bacterium (JM 109/plC20RNR1.1), described herein, that produces the TCL material in a fermentation process. The latter problem stems from the difficulty in determining the structure of the currently best TCL material diazoluminomelanin. A theoretical approach for the solution of this problem has been achieved by combining equations for delayed fluorescence, temperature determination by TCL, and the free energy equation for equilibrium reactions. It has led to an explanation for the stable display of steady-state energy disposition, illustrated by TCL, in phantoms without the expected disruption by thermal conduction or convection, at frequencies ranging from 2.06 GHz to 35 GHz.

Absorption↗
PubMed1999

Pulsed microwave induced light, sound, and electrical discharge enhanced by a biopolymer.

Intense flashes of light were observed in sodium bicarbonate and hydrogen peroxide solutions when they were exposed to pulsed microwave radiation, and the response was greatly enhanced by a microwave-absorbing, biosynthesized polymer, diazoluminomelanin. A FPS-7B radar transmitter, operating at 1.25 GHz provided pulses of 5.73 +/- 0.09 micros in duration at 10.00 +/- 0.03 pulses/s with 2.07 +/- 0.08 MW forward power (mean +/- standard deviation), induced the effect but only when the appropriate chemical interaction was present. This phenomenon involves acoustic wave generation, bubble formation, pulsed luminescence, ionized gas ejection, and electrical discharge. The use of pulsed microwave radiation to generate highly focused energy deposition opens up the possibility of a variety of biomedical applications, including targeting killing of microbes or eukaryotic cells. The full range of microwave intensities and frequencies that induce these effects has yet to be explored and, therefore, the health and safety implications of generating the phenomena in living tissues remain an open question.

Absorption↗
PubMed1999

Serum dioxin, insulin, fasting glucose, and sex hormone-binding globulin in veterans of Operation Ranch Hand.

We studied insulin, fasting glucose, and sex hormone-binding globulin (SHBG) in Air Force veterans exposed to Agent Orange and its contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), during the Vietnam War. The index subjects were veterans of Operation Ranch Hand, the unit responsible for aerial herbicide spraying in Vietnam from 1962-1971. Other Air Force veterans who served in Southeast Asia during the same period but were not involved with spraying herbicides served as comparisons. We assigned each Ranch Hand veteran based on his dioxin level to one of three exposure categories, named background, low, and high. Among nondiabetic veterans, we found the mean of the logarithm of insulin significantly increased in the high dioxin category. Additionally, in nondiabetic veterans the relation between SHBG and insulin interacted significantly with dioxin category on the log scale within strata defined by age and percent body fat. Among young (age, < or = 53 yr), lean (percent body fat, < or = 25%) nondiabetic veterans in the high category, the slope relating the logarithm of SHBG and the logarithm of insulin was significantly decreased. These findings suggest a compensatory metabolic relationship between dioxin and insulin regulation.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1995

Considerations for human exposure standards for fast-rise-time high-peak-power electromagnetic pulses.

Development of new emitter systems capable of producing high-peak-power electromagnetic pulses with very fast rise times and narrow pulse widths is continuing. Such directed energy weapons systems will be used in the future to defeat electronically vulnerable targets. Human exposures to these pulses can be expected during testing and operations. Development of these technologies for radar and communications purposes has the potential for wider environmental exposure, as well. Current IEEE C95.1-1991 human exposure guidelines do not specifically address these types of pulses, though limits are stated for pulsed emissions. The process for developing standards includes an evaluation of the relevant bioeffects data base. A recommendation has been made that human exposure to ultrashort electromagnetic pulses that engender electromagnetic transients, called precursor waves, should be avoided. Studies that purport to show the potential for tissue damage induced by such pulses were described. The studies cited in support of the recommendation were not relevant to the issues of tissue damage by propagated pulses. A number of investigations are cited in this review that directly address the biological effects of electromagnetic pulses. These studies have not shown evidence of tissue damage as a result of exposure to high-peak-power pulsed microwaves. It is our opinion that the current guidelines are sufficiently protective for human exposure to these pulses.

Animals↗
PubMed1994

Plant nitrate reductase gene fragments enhance nitrite production in activated murine macrophage cell lines.

Nitrate reductase (NR) gene fragments (1.1 kb and 800 bp) from the barley plant were incorporated into pSV2neo and transfected by electroporation into a variety of cell lines of different functionality. Only transfected murine macrophage cell lines demonstrated appreciably enhanced NO2- production (i.e., NR activity) both in the presence and absence of exogenous nitrate (NO3-). Addition of NO3- caused the greatest increase in NO2- production when macrophages were primed with interferon-gamma (INF-gamma) and lipopolysaccharide (LPS). Transfection of RAW 264.7 murine macrophages led to isolation of several novel neomycin-resistant subpopulations designated NR10(1), NR10(2) (both containing the 1.1 kb NR fragment) and NR800(5) (containing the 800 bp NR fragment). Similarly transfected nonleukocytic and leukocytic stem cell lines showed no significant NO2- production. Outside of the macrophage cell lines, only the murine T cell line EL-4 showed evidence of mild nitrite production enhancement. The mechanism of enhanced NO2- formation in NR transfected murine macrophages is unknown. However, study of these novel cells may lead to greater understanding of the expression of a plant NR in mammalian cells and highly controlled production of a cytotoxic molecule (NO2-) in macrophages.

Animals↗
PubMed1994

Synthesis of diazoluminomelanin (DALM) in HL-60 cells for possible use as a cellular-level microwave dosimeter.

Chemical and bacterial synthesis of a thermochemiluminescent polymer known as diazoluminomelanin (DALM) has been previously reported. This paper focuses on the intracellular synthesis of aminomelanin (AM) in mammalian cell lines and subsequent DALM synthesis from this core molecule. B16 melanoma cells, HL-60 myeloid leukemia cells, and RAW 264.7 macrophages show AM and DALM production. Macroscopic image analysis of HL-60 cell lysates containing DALM using the Quantitative Luminescence Imaging System (QLIS) showed increased chemiluminescence (CL) with increased microwave power input and increased temperature. This work represents a first step toward the goal of microscopic radiofrequency dosimetry of individual DALM-loaded cells using image analysis.

Biopolymers↗
PubMed1994

The ultimate biosensor.

The U.S. Air Force is concerned with the health and safety of personnel working with emitters of nonionizing electromagnetic radiation. Therefore, an understanding of basic mechanisms of interaction of this radiation with biosystems is essential. A nonresonance, nonclassical mechanism exists for interactions with biosystems under low energy (isothermal) field conditions. This mechanism is slow, or delayed, luminescence. Such a mechanism can form the basis for very sensitive biosensors naturally or artificially connected to metabolic and synthetic cellular processes.

Biosensing Techniques↗
PubMed1993

Luminol and diazoluminomelanin as indicators of HL-60 cell differentiation.

This paper describes use of a novel substituted melanin which is useful in detection of differentiating leukemia cells and their membranes. Comparisons of luminol-(5-amino-2,3-dihydro-1,4-phthalazinedione) and diazoluminomelanin (DALM)-mediated chemiluminescence (CL) were made with various types of differentiated and undifferentiated HL-60 whole cells, cell lysates, and membrane fractions. Luminol had a greater CL response than DALM with HL-60 promyelocytic stem cells and differentiated macrophage-like or neutrophil-like whole cell and cell lysate preparations. However, DALM showed markedly greater CL than luminol for membrane fractions derived from each cell type. The greatest luminol-dependent CL was observed for cell types high in myeloperoxidase (MPO). The greatest DALM-mediated CL was seen with cell types that are high in MPO or strong producers of superoxide (O2-) anions. In some cases, significant differences in CL could also be distinguished on the basis of inducing agent used [i.e. dimethylsulfoxide, all-trans retinoic acid or 12-o-tetradecanoylphorbol-13-acetate]. Both luminol- and DALM-dependent CL were strongly inhibited by preincubation of cellular preparations with 3-amino-L-tyrosine (a component of DALM). Taken together, these data suggest that the reaction mechanism of luminol favors interaction with cytoplasmic MPO whereas that of DALM favors membrane interactions. Thus, both reagents may be of use in assays to detect differentiating leukocytes or their cellular components.

Adult↗
PubMed1990

Interactions of methemoglobin and green hemoprotein in chemiluminescent gels.

Peroxidation of luminol (5-amino-2,3-dihydrophthalazine-1,4-dione) catalyzed by human green hemoprotein (GHP) and bovine methemoglobin (MetHb) in gels composed of cross-linked bovine serum albumin was examined. The chemiluminescence (CL) was followed with a low-light intensity video camera and imaging system attached to a circularly polarized microwave guide (2450 MHz) for heating the samples from 24 degrees C to 37 degrees C. Steady-state CL was maintained in the gels for 10 min. The intensity of the CL varied with temperature. When combined with MetHb in the same gel, GHP inhibited CL of MetHb from 83.6% to 98.2% over a fiftyfold concentration range of GHP. Although MetHb/GHP combination gels were inhibited, they generated a 6.12-fold CL per degree C change compared to a 0.19-fold per degree C change for MetHb gels and a 0.31-fold per degree C change for GHP gels. The data suggest an interaction between GHP and MetHb that inhibits the CL reaction, is not interfered with by large amounts of albumin, and is partially reversed by heating.

Animals↗
PubMed1990

Diazoluminomelanin: a synthetic luminescent biopolymer.

The purpose of this work was to synthesize a water-soluble derivative of 5-amino-2, 3-dihydro-1, 4-phthalazinedione (luminol) that generated sustained high level luminescence under physiologic conditions without the necessity of a catalyst. The derivative was made by a diazotization reaction with luminol and 3-amino-L-tyrosine. The resulting orange-brown anionic polymer has been given the trivial name of diazoluminomelanin (DALM). It was water soluble above and insoluble at or below pH 5.0. DALM luminesced when treated with hydrogen peroxide without the presence of a catalyst at pHs ranging from 6.5 to 12.0. Microgram quantities produced high levels of chemiluminescence for longer than 52 hr. Dried polymer generated a long-term stable electron spin resonance spectrum. The long-term chemiluminescence of DALM at pH 6.8-7.4 makes it a potentially useful reagent for detecting free radicals and peroxides in cellular and biochemical preparations.

Chemical Phenomena↗
PubMed1989

Involvement and relative importance of at least two distinct mechanisms in the effects of 2-mercaptoethanol on murine lymphocytes in culture.

2-Mercaptoethanol (2-ME) exerts several effects on murine lymphocytes in culture that might explain its ability to enhance survival and growth of these cells. The uptake of the essential amino acid cystine and consequently the maintenance of intracellular glutathione levels are enhanced by 2-ME. Furthermore, 2-ME (even in the disulfide form) causes lymphocytes to release thiols into the culture medium. These effects might protect the cells from oxidative damage. The additional cystine provided by treatment of lymphocyte cultures with 2-ME might also allow adequate protein synthesis to support survival and/or growth. This study was conducted to assess the relative importance of the antioxidant and protein synthesis effects of 2-ME. As expected, 2-ME increased cystine uptake at all concentrations that enhanced growth and survival, but four nonthiol antioxidants that enhanced growth and/or survival either did not substantially affect cystine uptake or decreased it and did not affect the release of cystine or its products. The results presented here demonstrate that antioxidant protection is necessary and sufficient for lymphocyte survival and that cystine uptake in untreated lymphocytes is sufficient to support the protein synthesis needed for survival and limited growth. However, we also noted that concentrations of 2-ME that stimulated maximal growth more than doubled protein synthesis as measured at 8 hr. Thus the portion of the effects of 2-ME not accounted for by antioxidant action could be accounted for by enhanced protein synthesis.

Animals↗
PubMed1989

Quantitative aspects of the feeder cell phenomenon: direct assessment of enhanced cystine uptake by lymphocytes.

It has been suggested that feeder cells and 2-mercaptoethanol enhance the survival and growth of murine lymphocytes in culture by increasing cysteine availability. We previously reported that although feeder cells produce thiols, they support lymphocyte growth at densities too low for measurable thiol production. This suggested that increasing the availability of cysteine might not be the major mechanism of feeder cell action. In the present study, [35S] cystine was used to directly monitor cyst(e)ine uptake in lymphocyte-feeder cell co-cultures. The results demonstrate that feeder cells substantially increase cyst(e)ine uptake by lymphocytes, even in the absence of detectable free thiols. Data are presented which suggest an explanation for this unexpected observation.

Animals↗
PubMed1988

Quantitative aspects of the feeder cell phenomenon: mechanistic implications.

It has been proposed that feeder cells function by supplying lymphocytes with the amino acid cysteine (a thiol compound). The results presented here indicate that thiols are the critical element of the feeder cell phenomenon. Specifically, we noted that the rank of thiol production by four different feeder cell lines corresponds to their relative abilities to support a lymphocyte cell line, CTLL-2. In addition, increasing thiol production by the feeder cells with lipopolysaccharide increased their support of CTLL-2 cells and decreasing it with homocysteate decreased support of CTLL-2 cells. However, it was also noted that substantial (up to 79% maximal) support of CTLL-2 growth was provided by feeder cell concentrations which could not produce detectable levels of free thiols. This prompted us to propose an alternative mechanism for the feeder effect which would explain these apparently paradoxical findings.

Animals↗
PubMed1988

Green hemoprotein of erythrocytes: methemoglobin superoxide transferase.

Influences of base (pH 10), heat (50 degrees C), microwave radiation (2450 MHz, 103 +/- 4 W/kg), and hydrogen peroxide (5.6 mM) generated by glucose oxidase on oxidation of human oxyhemoglobin to methemoglobin were examined. Conversion of oxyhemoglobin to methemoglobin was followed by the difference in absorbancy of 540 or 542 nm and 576 nm wavelength light versus time. Fresh basic hemolysates auto-oxidized on heating with a zero order rate constant, implying that hemoglobin or another protein saturated with oxyhemoglobin catalyzed the oxidation. Simultaneous microwave irradiation inhibited thermally induced auto-oxidation on the average by 28.6%. However, there was great variability among samples and a decrease in auto-oxidation with aging of individual samples. The auto-oxidation rate was independent of initial oxyhemoglobin concentration. Oxidation of partially purified oxyhemoglobin by hydrogen peroxide was not influenced by microwave irradiation. Adding green hemoprotein isolated from human erythrocytes to the oxyhemoglobin/glucose oxidase reaction mixture yielded absorption spectra (500-600 nm) that were a combination of oxyhemoglobin, deoxyhemoglobin, and methemoglobin spectra. Green hemoprotein was labile in hemolysates but stable in a partially purified ferric form. These results imply that thermally unstable reduced green hemoprotein can reverse oxidation of oxyhemoglobin by hydrogen peroxide and could mediate the thermally induced and microwave inhibited auto-oxidation of oxyhemoglobin.

Erythrocytes↗