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D E Burger

Publications and source records attributed to D E Burger.

13 recordsLinked to original sources
PubMed1991

The use of K X-ray fluorescence for measuring lead burden in epidemiological studies: high and low lead burdens and measurement uncertainty.

X-ray fluorescence (XRF), a rapid, noninvasive, low-radiation-dose method of measuring bone lead content, has emerged as a promising tool for providing an integrated estimate of low-level lead accumulation in epidemiological studies. Our group has settled on an XRF instrument that utilizes K X-rays (K-XRF) and normalizes the measurement to bone calcium. The unit of measurement provided is in micrograms of lead/gram bone mineral, an accurate proxy for micrograms of lead/gram bone ash. An estimate of measurement uncertainty is generated from the counting statistics and is theoretically dependent on several factors, primarily duration of measurement and bone mass. Data from pilot studies of community-exposed adults and workers with varying degrees of occupational lead exposure demonstrated that the K-XRF instrument can easily distinguish between populations with occupational versus environmental lead exposures. Among all subjects, bone lead increased with age. Larger measurement uncertainty was significantly associated with being female, greater subject weight, and smaller lead burdens.

Adult↗
PubMed1989

X-ray fluorescence: issues surrounding the application of a new tool for measuring burden of lead.

Studies of lead toxicity would greatly benefit from a convenient, noninvasive measure of body lead burden. X-ray fluorescence (XRF) promises to provide such a measure by rapidly estimating lead content in bone, the repository of greater than 95% of an adult's lead stores (73% in children). Two separate XRF techniques exist, L-XRF and K-XRF. They differ in terms of calibration method and type of bone sampled. They also involve different radiation energies; however, radiation doses and concomitant risks are similarly low. Since interpretation of an XRF measurement depends to an extent on the distribution of lead in the skeleton, this topic is reviewed. Available data suggest that trabecular and cortical bone comprise two distinct compartments with regard to lead kinetics. Within each compartment, however, there also appears to be a significant degree of variability. Furthermore, there is evidence to suggest that the subperiosteal surface layer of cortical bone has a pattern of lead absorption and release that is different from the rest of cortical bone. This may have implications for (1) the choice of XRF technique, since the L-XRF technique measures lead in surface bone, whereas the K-XRF technique derives an estimate of lead from the full thickness of bone, and (2) the selection of bone sites for taking XRF measurements. More research is necessary to fully optimize the applicability of the XRF instrument.

Adolescent↗
PubMed1984

Lectin receptor proximity on HL-60 leukemia cells determined by fluorescence energy transfer using flow cytometry.

Fluorescence energy transfer using flow cytometric measurements was utilized to determine the proximity of concanavalin A receptors on the surface of HL-60 promyelocytic leukemia cells before and after induction of differentiation. The HL-60 cells were induced to differentiate into granulocytes using dimethylsulfoxide and into macrophages using 12-O-tetradecanoylphorbol-13-acetate. Concanavalin A was labeled with either fluorescein (donor chromophore) or tetramethylrhodamine (acceptor chromophore), and these species were used to determine lectin proximity. With granulocytic differentiation, the amount of concanavalin A bound remained constant, but a decrease in receptor density was observed. During macrophage differentiation, however, both receptor density and receptor number increased. The increase in concanavalin A binding during differentiation appears to be a result of maturation rather than an initiating event.

Cell Line↗
PubMed1982

Extraction of morphological features from biological models and cells by Fourier analysis of static light scatter measurements.

Models of biological cells of varying geometric complexity were used to generate data to test a method of extracting geometric features from light scatter distributions. Measurements of the dynamic range and angular distribution of intensity and light scatter from these models was compared to the distributions predicted by a complete theory of light scatter (Mie) and by diffraction theory (Fraunhofer). An approximation to the Fraunhofer theory provides a means of obtaining size and shape features from the data by a spectrum analysis. Experimental verification using nucleated erythrocytes as the biological material show the potential application of this method for the extraction of important size and shape parameters from light scatter data.

Animals↗
PubMed1982

Analysis of glycosaminoglycans of flow sorted cells: incorporation of [35S]sulfate and [3H]glucosamine into glycosaminoglycans of B16-F10 cells during the cell cycle.

The incorporation of [35S]sulfate and [3H] glucosamine into cetyl pyridinium chloride (CPC) precipitable glycosaminoglycans was determined in B16-F10 cultured cells sorted with respect to DNA content. Incorporation into surface material was measured indirectly as the difference between the radioactivity of control and trypsin treated cells. Approximately 80% of the total cellular [35S] sulfate labeled CPC precipitable material, but only 5% of that labeled by [3H]glucosamine, was removed by this mild trypsin treatment. Incorporation of [35S]sulfate into the trypsin removable surface material increased progressively from G1 to S to F2 + M in both long-term (48 hours) and short-term (1 hour) labeled cells, while the ratio of surface to total incorporated [35S]sulfate remained relatively constant. Incorporation of [35S]sulfate into total cellular glycosaminoglycans in long- and short-term labeled cells increased as cells progressed from G1 to S to G2 + M; the incorporation of [3H]glucosamine into CPC precipitable material also increased progressively from G1 to S to G2 + M in long-term labeled cells but was greater during S phase relative to G1 or G2 + M in short-term labeled cells. The degree of sulfation of glycosaminoglycans as represented by the ratio of [35S]sulfate to [3H]glucosamine of double labeled cells was relatively constant in long-term labeled cells but was increased during the G1 and G2 + M phases of short-term labeled cells. Comparison of the degree of sulfation of short-term with long-term labeled cells suggests that highly sulfated glycosaminoglycans may be turned over more rapidly during G1 and G2 + M phases of the cell cycle.

Animals↗
PubMed1982

Prolactin storage in a clonal strain of rat pituitary tumor cells is cell-cycle dependent.

GH4C1 cells (CH cells) are a clonal strain of rat pituitary tumor cells which secrete prolactin. We measured intracellular prolactin at different stages of the cell cycle using flow microfluorometry. Prolactin was stained by an indirect immunocytochemical technique using fluorescein isothiocyanate (FITC)-conjugated antiserum, and DNA was stained simultaneously with propidium iodide. We found that prolactin storage in GH cells was cell-cycle dependent; prolactin storage increased as cells passed from G1 to S to G2 + M. We have shown previously that insulin and 17 beta-estradiol act synergistically to increase intracellular prolactin three- to sevenfold and slow the rate of cell growth to approximately 70% of control cells. In this study we observed that insulin and estradiol increased prolactin storage at each stage of the cell cycle but did not affect the cell-cycle distribution of the population even though cell growth was slowed. We conclude that insulin and estradiol did not increase prolactin storage by affecting the cell-cycle distribution of the population.

Animals↗
PubMedDate not supplied

X-ray fluorescence measurements of lead burden in subjects with low-level community lead exposure.

A k-x-ray fluorescence (K-XRF) instrument that can measure in vivo bone lead at low levels was used on a population of 34 adults with no known history of excessive lead exposure. A questionnaire that gathered information relevant to occupational and environmental lead exposure was administered prior to the measurement. A 30-min measurement that produced an average estimated uncertainty of 6 mcg lead/g bone mineral was taken at the mid-tibial diaphysis for each subject. Eighteen subjects had bone lead levels below the measurement uncertainty. The remainder had bone lead levels ranging up to 21 mcg lead/g bone mineral. Bone lead levels were greater among older subjects. Among young adult subjects, bone lead levels greater than the measurement uncertainty were confined entirely to subjects who had grown up in housing that was estimated to have been build prior to 1955. Such a childhood environment is at high risk of fostering exposure to biologically absorbable lead through ingestion of lead paint-contaminated dust and lead pipe-contaminated water. We conclude that the K-XRF technique has the potential to distinguish between low levels of lead burden in epidemiologic studies.

Adult↗
PubMedDate not supplied

Slide-based laser scanning cytometry.

OBJECTIVE: To show that laser scanning cytometry (LSCM) can provide data equivalent to flow cytometry (FCM) data and furnish a number of benefits, including cell relocation for visualization and several additional measurement features that may make it more suitable than FCM for pathology laboratories. STUDY DESIGN: A laser scanning cytometer, the LSC, was developed. Several instruments, at sites in the United States and Japan during the last two years, provided data characterizing the instrument and its usefulness. RESULTS: Data describing the sensitivity, precision, accuracy, utility of added measurement features and cell relocation capabilities of the LSC are presented. The data illustrate the applicability of the LSC to multiparameter DNA ploidy studies, resolution of phases of the cell cycle and cytogenetics. CONCLUSION: Because it is microscope based and measures cells on a slide, not in a flow chamber; records the position of each cell on the slide; and has higher resolution, LSCM provides a number of benefits that may make it more suitable than FCM for pathology laboratories.

Animals↗