A detailed urinary excretion time course study of captan and folpet biomarkers in workers for the estimation of dose, main route-of-entry and most appropriate sampling and analysis strategies

Captan and folpet are two fungicides largely used in agriculture, but biomonitoring data are mostly limited to measurements of captan metabolite concentrations in spot urine samples of workers, which complicate interpretation of results in terms of internal dose estimation, daily variations according to tasks performed, and most plausible routes of exposure. This study aimed at performing repeated biological measurements of exposure to captan and folpet in field workers (i) to better assess internal dose along with main routes-of-entry according to tasks and (ii) to establish most appropriate sampling and analysis strategies. The detailed urinary excretion time courses of specific and non-specific biomarkers of exposure to captan and folpet were established in tree farmers (n = 2) and grape growers (n = 3) over a typical workweek (seven consecutive days), including spraying and harvest activities. The impact of the expression of urinary measurements [excretion rate values adjusted or not for creatinine or cumulative amounts over given time periods (8, 12, and 24 h)] was evaluated. Absorbed doses and main routes-of-entry were then estimated from the 24-h cumulative urinary amounts through the use of a kinetic model. The time courses showed that exposure levels were higher during spraying than harvest activities. Model simulations also suggest a limited absorption in the studied workers and an exposure mostly through the dermal route. It further pointed out the advantage of expressing biomarker values in terms of body weight-adjusted amounts in repeated 24-h urine collections as compared to concentrations or excretion rates in spot samples, without the necessity for creatinine corrections.

Spinal cord T-cell infiltration in the spared nerve injury model of neuropathic pain: a time course study

Background : Numerous studies have shown that immune cells infiltrate the spinal cord after peripheral nerve injury and that they play a major contribution to sensory hypersensitivity in rodents. In particular, the role of monocyte-derived cells and T lymphocytes seems to be prominent in this process. This exciting new perspective in research on neuropathic pain opens many different areas of work, including the understanding of the function of these cells and how they impact on neural function. However, no systematic description of the time course or cell types that characterize this infiltration has been published yet, although this seems to be the rational first step of an overall understanding of the phenomenon. Objective : Describe the time course and cell characteristics of T lymphocyte infiltration in the spinal cord in the Spared Nerve Injury (SNI) model of neuropathic pain in rats. Methods : Collect of lumbar spinal cords of rats at days 2, 7, 21 and 40 after SNI or sham operation (n=4). Immunofluorescence detecting different proteins of T cell subgroups (CD2+CD4+, CD2+CD8+, Th1 markers, Th2 markers, Th17 markers). Quantification of the infiltration rate of the different subgroups. Expected results : First, we expect to see an infiltration of T cells in the spinal cord ipsilateral to nerve injury, higher in SNI rats than in sham animals. Second, we anticipate that different subtypes of T cells penetrate at different time points. Finally, the number of T lymphocytes are expected to decrease at the latest time point, showing a resolution of the process underlying their infiltrating the spinal cord in the first place. Impact : A systematic description of the infiltration of T cells in the spinal cord after peripheral nerve injury is needed to have a better understanding of the role of immune cells in neuropathic pain. The time course that we want to establish will provide the scientific community with new perspectives. First, it will confirm that T cells do indeed infiltrate the spinal cord after SNI in rats. Second, the type of T cells infiltrating at different time points will give clues about their function, in particular their inflammatory or anti-inflammatory profile. From there on, other studies could be lead, investigating the functional side of the specific subtypes put to light by us. Ultimately, this could lead to the discovery of new drugs targeting T cells or their infiltration, in the hope of improving neuropathic pain.

Metric Short Course for the Office of Bridges and Structures, HR-378, 1995

This metric short course was developed in response to a request from the Office of Bridges and Structures to assist in the training of engineers in the use of metric units of measure which will be required in all highway designs and construction after September 30, 1996 (CFR Presidential Executive Order No. 12770). The course notes which are contained in this report, were developed for a half-day course. The course contains a brief review of metrication in the U.S., metric units, prefixes, symbols, basic conversions, etc. The unique part of the course is that it presents several typical bridge calculations (such as capacity of reinforced concrete compression members, strength of pile caps, etc.) worked two ways: inch-pound units throughout with end conversion to metric and initial hard conversion to metric with metric units throughout. Comparisons of partial results and final results (obtained by working the problems the two ways) are made for each of the example problems.

Dense Concrete Layer as Top Course of Bridge Deck Construction, HR-502, 1990

The use of deicing salts in this part of the country is a necessity to remove ice from our bridges. The use of these salts has always been a problem since the chloride-ions penetrate the concrete and reach the steel and cause corrosion which eventually cause deterioration of both the steel and concrete. One method used to try to prevent this from happening was to apply a waterproof membrane to the concrete after it was placed. This method did help, but was not cost effective as the longevity of the membrane system was of relatively short duration. For this reason, this research project was initiated. After the original deck was placed a second layer of concrete about 1 1/2" thick was placed on top. Biennial evaluation of the decks included testing for delaminations and steel corrosion. Cores were also obtained for a chloride analysis. Testing and observations showed the two-layer bridge deck to be effective in preventing corrosion. Since the time this project was initiated, epoxy steel has been introduced and is a cost effective way to protect the steel from corrosion.

Asbestos Fibers in Type B Asphaltic Concrete Surface Course, MLR-67-1, 1968

The Standard Specifications for this project included requirements for placing two 500 foot test sections of Type B asphaltic concrete with 1-1/2 per cent asbestos fibres (mix size 3/8 inch, lift thickness 3/4 inch) as part of the regular construction of the surface course. These requirements were designed to provide asbestos modified mixtures for laboratory analysis and road performance evaluation. This report provides the preliminary results and analysis of test data obtained from tests on the mixtures placed on the roadway. Previous research by G. S. Zuelke (1) and J. H. Kestzman et al (2) indicated that asphaltic concrete mixtures modified with asbestos fibres improved stability, decreased permeability, and allowed the use of higher bitumen contents. This study indicated that the addition of asbestos fibres would permit the use of higher bitumen contents, theoretically improving durability, without adverse results. An indication was also obtained to the effect that asbestos mixtures were more difficult to compact in the field.

Factors Influencing Stability of Granular Base Course Mixes, Progress Report, HR-99, 1965

The problems of laboratory compaction procedures, the effect of gradation and mineralogy on shearing strength, and effect of stabilizing agents on shearing strength of granular base course mixes are discussed. For the materials tested, a suitable laboratory compaction procedure was developed which involves the use of a vibratory table to prepare triaxial test specimens. A computer program has been developed to facilitate the analysis of the test data of the effect of gradation and mineralogy on shearing strength of soils. The effects of the following materials have been selected for evaluation as stabilizing agents’ portland cement, sodium and calcium chloride, lime organic cationic waterproofer, and asphaltic materials.

Factors Influencing Stability of Granular Base Course Mixes, Progress Report, HR-99, 1964 (April)

The problems of laboratory compaction procedures, the effect of gradation and mineralogy on shearing strength, and effect of stabilizing agents on shearing strength of granular base course mixes are discussed. For the materials tested, a suitable laboratory compaction procedure was developed which involves the use of a vibratory table to prepare triaxial test specimens. A computer program has been developed to facilitate the analysis of the test data of the effect of gradation and mineralogy on shearing strength of soils. The effects of the following materials have been selected for evaluation as stabilizing agents’ portland cement, sodium and calcium chloride, lime organic cationic waterproofer, and asphaltic materials.

Factors Influencing Stability of Granular Base Course Mixes, Progress Report, HR-99, 1964 (November)

The problems of laboratory compaction procedures, the effect of gradation and mineralogy on shearing strength, and effect of stabilizing agents on shearing strength of granular base course mixes are discussed. For the materials tested, a suitable laboratory compaction procedure was developed which involves the use of a vibratory table to prepare triaxial test specimens. A computer program has been developed to facilitate the analysis of the test data of the effect of gradation and mineralogy on shearing strength of soils. The effects of the following materials have been selected for evaluation as stabilizing agents’ portland cement, sodium and calcium chloride, lime organic cationic waterproofer, and asphaltic materials.

Lime or Chloride Treatment of Granular Base Course Materials, HR-99

Results are presented of triaxial testing of three crushed limestones to which either hydrated high-calcium lime, sodium chloride or calcium chloride had been added. Lime was added at rates of 1, 3, 10 and 16 percent, chlorides were added at 0.5 percent rate only. Speciments were compacted using vibratory compaction apparatus and were tested in triaxial compression using lateral pressures from 10 to 100 psi. Triaxial test results indicate that: (1) sodium chloride slightly decreased the angle of internal friction and increased cohesion, (2) calcium chloride slightly increased the angle of internal friction and decreased cohesion, and (3) lime had no appreciable effect on angle of internal friction but increased cohesion, decreased density and increased pore water pressure.

Improvement of Granular Base Course Materials with Portland Cement, Special Report, HR-99

A highway base course may be defined as a layer of granular material which lies immediately below the wearing surface of a pavement and must possess high resistance to deformation in order to withstand pressures imposed by traffic. A material commonly used for base course construction is crushed limestone. Sources of limestone, acceptable for highway bases in the state of Iowa, occur almost entirely in the Pennsylvanian, Mississippian and Devonian strata. Performance records of the latter two have been quite good, while material from the Pennsylvanian stratum has failed on numerous occasions. The study reported herein is one segment of an extensive research program on compacted crushed limestone used for flexible highway base courses. The primary goals of the total study are: 1. Determination of a suitable and realistic laboratory method of compaction. 2. Effect of gradation, and mineralogy of the fines, on shearing strength. 3. Possible improvement of the shear strength with organic and inorganic chemical stabilization additives. Although the study reported herein deals primarily with the third goal, information gathered from work on the first two was required for this investigation. The primary goal of this study was the evaluation of various factors of stability of three crushed limestones when treated with small amounts of type I Portland cement. Investigation of the untreated materials has indicated that shear strength alone is not the controlling factor for stability of crushed stone bases. Thus the following observations were made in addition to shear strength parameters, to more adequately ascertain the stability of the cement treated materials: 1. Volume change during consolidation and shear testing. 2. Pore pressure during shear. The consolidated-undrained triaxial shear test was used for determination of the above factors.