The spectroscopic foundation of radiative forcing of climate by carbon dioxide.

The radiative forcing (RF) of carbon dioxide (CO2) is the leading contribution to climate change from anthropogenic activities. Calculating CO2 RF requires detailed knowledge of spectral line parameters for thousands of infrared absorption lines. A reliable spectroscopic characterization of CO2 forcing is critical to scientific and policy assessments of present climate and climate change. Our results show that CO2 RF in a variety of atmospheres is remarkably insensitive to known uncertainties in the three main CO2 spectroscopic parameters: the line shapes, line strengths, and half widths. We specifically examine uncertainty in RF due to line mixing as this process is critical in determining line shapes in the far wings of CO2 absorption lines. RF computed with a Voigt line shape is also examined. Overall, the spectroscopic uncertainty in present-day CO2 RF is less than 1%, indicating a robust foundation in our understanding of how rising CO2 warms the climate system.

Abscisic Acid Induces Formation of Floating Leaves in the Heterophyllous Aquatic Angiosperm Potamogeton nodosus.

Potamogeton nodosus tubers produce floating-type instead of submersed-type leaves when exposed to 10(-5) molar synthetic abscisic acid. Abscisic acid-induced leaves have stomata on upper leaf surfaces and higher width/length ratios than controls. These effects are wholly or partially overcome by simultaneous exposure to abscisic acid combined with gibberellic acid, kinetin, or benzyladenine.

Glycosaminoglycan synthesis by a cell line (C1-S1) established from a preneoplastic mouse mammary outgrowth.

We have measured the synthesis of several types of glycosaminoglycans by a line of mouse mammary epithelial cells (C1-S1) established from a hyperplastic nodule outgrowth. These epithelioid cells do not grow readily in vivo. Subconfluent monolayer cultures of C1-S1 cells produced more hyaluronic acid than heparan sulfate, but the opposite was true in confluent cultures. At saturation density in culture, the cell surface glycosaminoglycan of C1-S1 cells was approximately 80% heparan sulfate. For comparison, data are also reported on two related tumorigenic sublines (+SA and -SA) established from a spontaneous tumor in a hyperplastic outgrowth. These cells produced mostly hyaluronic acid even when confluent. Furthermore, the net rate of hyaluronic acid synthesis was higher in the more aggressive tumor cells (+SA). The data are consistent with the interpretation that a hyaluronic acid-rich, heparan sulfate-poor environment is associated with the growth of mammary epithelial cells and conversely that a heparan sulfate-rich environment may restrict growth. The glycosaminoglycan environment may thus contribute to growth modulation in vivo.

Serum uridine levels in patients receiving N-(phosphonacetyl)-L-aspartate.

Serum uridine levels of N-(phosphonacetyl)-L-aspartate-treated patients from Phase 1 and continuing trials receiving 1000 to 2000 mg/sq m/day were measured by reverse-phase high-pressure liquid chromatography. For the five patients studied, the predose serum levels ranged from 2.6 to 64. microM, well within the normal range of 1.9 to 8.9 microM. All serum uridine levels decreased in the first 24 hr, but the drop was quite variable (7 to 65%). Uridine levels in all five patients remained being 37 to 85% at differing time points. The only patient to show a daily decrease was the only responder and the patient with the largest decrease. N-(Phosphonacetyl)-L-aspartate appears to have a limited reductive effect on human serum uridine levels.

Effect of inhibitors of the de novo pyrimidine biosynthetic pathway on serum uridine levels in mice.

Since C57BL X DBA F1 (hereafter called BDF1) mice possess a relatively constant concentration of serum uridine [9.7 +/- 1.3 (S.D.) nmol/ml], circulating uridine is available to cells with an intact pyrimidine salvage pathway and thus could influence the effectiveness of certain antitumor agents which inhibit de novo pyrimidine biosynthesis and whose cytotoxic properties are reversed by uridine. Three inhibitors of the de novo pyrimidine biosynthetic pathway were studied to determine their effects on circulating uridine concentration in BDF1 mice. Pyrazofurin and 6-azauridine were found to have no significant effect on serum uridine levels when administered as a single dose or on 4 consecutive days. In contrast, N-(phosphonacetyl)-L-aspartate reduced serum uridine levels by 55% when administered either as a single dose or on 4 consecutive days. This reduction could contribute to the antitumor effectiveness of N-(phosphonacetyl)-L-aspartate by limiting the rescue of cells possessing a salvage pathway. D-Galactosamine, a stimulator of the de novo pyrimidine pathway, was also studied and found to increase total liver uridine (uridine plus uracil nucleotides and uridine diphosphate esters) by 4-fold at 8 hr, returning to normal by 24 to 48 hr. However, these large effects were not reflected in the serum.

Glycosaminoglycan synthesis by subpopulations of epithelial cells from a mammary adenocarcinoma.

Glycosaminoglycan synthesis by two subpopulations of a mouse mammary tumor cell line was compared. The two sublines express distinctly different growth characteristics in vitro and in vivo which indicate differences in growth regulation. Newly made glycosaminoglycans were recovered from the culture media, the cell surfaces, and residual cellular material. The cell population which grows more aggressively in vivo (+SA subline, a subline that grows in soft agarose) incorporated about 8 times more [14C]glucosamine per cell into total glycosaminoglycans than did the slower-growing population (-SA subline, which does not grow in soft agarose). Appropriate control experiments indicated that the apparent difference in rates of synthesis was not due to discrepancies in glucosamine uptake. The main residual cellular molecule labeled was heparan sulfate, but the predominant molecule at the cell surface and in the culture fluid was hyaluronic acid. Overall, +SA cells synthesized more hyaluronic acid and -SA cells synthesized more heparan sulfate; in both cell populations, these two molecules accounted for about 90% of total glycosaminoglycans produced.

Cyclophosphamide and 4-Hydroxycyclophosphamide/aldophosphamide kinetics in patients receiving high-dose cyclophosphamide chemotherapy.

Using a recently developed gas chromatography and mass spectrometry method to determine whole-blood cyclophosphamide (CP) and 4-hydroxycyclophosphamide/aldophosphamide (4-HO-CP/AP) concentrations, we investigated their pharmacokinetics in women receiving CP therapy. Patients (n = 18) received one or two courses of CP: (a) a 90-min i.v. infusion (4 g/m2) followed by a 96-h i.v. infusion (6 g/m2) in combination with high-dose thiotepa; or (b) a 96-h i.v. infusion (6 g/m2) in combination with high-dose thiotepa. Whole-blood exposures to CP [area under the whole blood concentration versus time curve (AUCCP)] and 4-HO-CP/AP (AUC4HOCP) between courses 1 and 2 were compared after normalization to dose (g/m2). A nonproportional increase was observed for the AUCCP between the first course [1112 micrometer. h/g/m2 +/- 14% coefficient of variation (CV)] and the second course (1579 micrometer . h/g/m2 +/- 28% CV) (P < 0.001). In contrast, the AUC4HOCP (27 micrometer . h/g/m2 +/- 25% CV) determined for the first course was 29% higher than the AUC4HOCP (21 micrometer . h/g/m2 +/- 26% CV) for the second course (P < 0.01). The interpatient whole-blood exposures to both CP and 4-HO-CP/AP were remarkably consistent in this patient population with percent CVs ranging from 14 to 28%. Because thiotepa (800 mg/m2) was administered simultaneously with CP during the second course of treatment, possible inhibition of CP metabolism by thiotepa was investigated using human liver microsomes in vitro. IC50 values determined for inhibition of CP metabolism in three individual liver donors ranged from 1.0 to 40 micrometer. However, the clinical relevance of this observation has not been established.

Isolation, structural determination, and biological activity of 6 alpha-hydroxytaxol, the principal human metabolite of taxol.

The principal biotransformation product of taxol was found to be identical for human hepatic microsomes, human liver slices, and patient bile samples. We have isolated this metabolite from the bile of a patient given taxol, and we report its structure and its cytotoxicity relative to taxol. The NMR and SIMS data presented here indicate that, in humans, taxol is regiospecifically hydroxylated at the 6-position on the taxane ring and that this hydroxyl is stereospecifically placed trans to the hydroxyl at position 7, yielding 6 alpha-hydroxytaxol. This metabolite is apparently not formed in rats. Tests of the growth inhibition potential of 6 alpha-hydroxytaxol versus taxol in two human tumor cell lines showed that the metabolite was approximately 30-fold less cytotoxic than taxol. Thus the cytochrome P-450-mediated biotransformation of taxol to 6 alpha-hydroxytaxol can be classified as a detoxification reaction.

An in vitro model of neoplastic progression in murine epithelial cells.

We have developed an epithelial cell line derived from mouse liver which represents a spectrum of malignant progression. When inoculated into mice at low passage, the cells induced benign cysts; after extensive subcultures, the same line induced low grade adenocarcinomas. A variant of these cells with increased invasive and metastatic potential was selected. In culture, growth in methocel correlated with acquisition of malignant potential while increased homotypic aggregation correlated with metastatic ability. These cultures should be extremely valuable for studies on the nature of epithelial cell malignancy, the most common form of human cancer.

Comparison of a new latex agglutination assay with indirect immunofluorescence to detect varicella-zoster antibodies.

A comparison of a latex agglutination assay with an immunofluorescence assay for the detection of varicella-zoster virus antibodies is described. The two tests were completely concordant in their results; therefore the latex agglutination test may be valuable for laboratories that require rapid turnaround time or have limited personnel and equipment.

Oxime derivatives of the intermediary oncostatic metabolites of cyclophosphamide and ifosfamide: synthesis and deuterium labeling for applications to metabolite quantification.

There is ongoing interest in the selective, quantitative analysis of the cyclophosphamide metabolites 4-hydroxycyclophosphamide (2a) and aldophosphamide (3a) because these tautomers are generally believed to play a key role in oncostatic selectivity and metabolite transport. O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine (C6F5CH2ONH2, 1 equiv) provided for the complete conversion (by 31P NMR, 60% reaction within 15 min at 20 degrees C) of 2a/3a (17 mM in H2O/CH3OH) to E/Z-aldophosphamide O-(2,3,4,5,6-pentafluorobenzyl)oxime [C6F5CH2ON = CHCH2CH2OP-(O)(NH2)N(CH2CH2Cl)2; E:Z = 54:46 (+/- 3% average deviation)]. Under these conditions, the oxime exhibited little (6%) decomposition over 3 weeks. Parallel studies showed that 4-hydroxyifosfamide/aldoifosfamide reacted completely to give the analogous aldoifosfamide oxime [C6F5CH2ON = CHCH2CH2OP(O)(NHCH2CH2Cl)2; E:Z = 52:48 (+/- 1% average deviation)] with 50% reaction within 15 min at 20 degrees C with no product decomposition over 3 weeks. In aqueous methanol and with 2 equiv C6F5CH2ONH2, clinically useful 4-hydroperoxycyclophosphamide (10 mM; tau 1/2 = 10 min, 37 degrees C) and its isomer 4-hydroperoxyifosfamide (10 mM; tau 1/2 = 25 min, 20 degrees C) underwent complete conversion to the corresponding aldehyde oximes. Each oxime was synthesized with deuterium in the chloroethyl moieties for use as internal standards in GC/MS applications.

The Public Health Service role in the disposal of chemical munitions.

Within the last decade, the Centers for Disease Control (CDC) has increasingly emphasized environmental public health activities. The Center for Environmental Health (CEH), one of nine major units of the CDC, was established as a focus for assessment and prevention of environmentally related diseases. Many new, legislatively mandated programs have been delegated to CEH. One such mandated responsibility in Public Laws 91-121 and 91-441 directs the Department of Health and Human Services or its designee to review the Department of Defense (DOD) plans to dispose of or to transport chemical warfare agents. The Chemical Munitions Demilitarization Program, CEH, reviews DOD plans and makes recommendations to ensure that hazards to public health and safety have been provided for in the plans. In addition, these CEH staffers periodically review approved activities at DOD facilities, assessing their monitoring and evaluation programs. CEH staffers also contact State and local health and environmental agencies to identify and evaluate any concerns of the agencies or the public relating to these activities.

The aquatic fate of triclopyr in whole-pond treatments.

The aquatic fate of the triethylamine salt formulation of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) was determined in whole-pond applications in closed (no water exchange) systems in California, Missouri and Texas in two studies conducted in 1995 and 1996. These studies determined dissipation rates of triclopyr and its principal metabolites, 3,5,6-trichloropyridinol (TCP) and 3,5,6-trichloro-2-methoxypridine (TMP) in water, sediment and finfish. Ponds at each site containing a healthy biological community were treated at 2.5 mg AE litre-1 triclopyr. Water and sediment samples were collected through 12 weeks post-treatment, and non-target animals were collected through 4 weeks post-treatment. Dissipation rates for triclopyr, TCP and TMP were similar at each of the study sites, despite differences in weather, water quality, biotic community, light transmission and geographic location. Half-lives of triclopyr in water ranged from 5.9 to 7.5 days, while those of TCP and TMP ranged from 4 to 8.8 and 4 to 10 days, respectively. Levels of triclopyr and TCP declined in sediments at half-lives ranging from 2.8 to 4.6 days and 3.8 to 13.3 days, respectively. No TMP was detected in sediment. Triclopyr and TCP cleared from fish in relation to concentrations found in the water column. TMP levels in fish were generally an order of magnitude higher than levels of triclopyr and TCP, particularly in the visceral portion of the animals. No adverse effects on water quality or on the non-target biotic community were found following triclopyr applications. Results of these studies were comparable to those of triclopyr dissipation studies conducted in reservoirs, lakes and riverine systems in Georgia, Florida, Minnesota and Washington, indicating that the degradation and dissipation of triclopyr and its metabolites are similar in representative systems throughout the USA.

Collection and cultivation in vitro of equine mammary macrophages.

Equine macrophages were obtained from female Shetland ponies by injection of Escherichia coli lipopolysaccharide through the lactiferous ducts of the mammary gland. After 6 to 11 days, balanced salt solution was injected into the mammary gland to wash out accumulated cells. Harvested cells contained a mixture of macrophages, lymphocytes, and neutrophils, with the majority of the cells of mononuclear type. In culture, cells adherent after 24 hours were characterized as macrophages by morphologic features, nonspecific esterase staining, and by the presence of complement and immunoglobulin receptors. These cultures were grown to a variety of culture media. A basal medium, consisting of 15% equine serum and 10% bovine fetal serum in conjunction with RPMI 1640 medium containing 20 mM HEPES buffer, was the most effective for maintaining spreading and adhesion of cells. Conditioned medium from mouse fibroblast cultures (L cells), added at 30% to the basal medium, improved cell monolayers by reducing giant cell formation and prolonging cell adhesion.

Culture characteristics and tumorigenicity of the equine sarcoid-derived MC-1 cell line.

MC-1 is an equine sarcoid-derived cell line which spontaneously releases a retrovirus possessing genomic sequence homology with an inducible endogenous retrovirus of normal equine cells. A complete characterization of MC-1 tumor cells was undertaken, including morphology, growth kinetics, and saturation density, selective growth in semisolid media, uptake of 2-deoxyglucose, and tumorigenicity in athymic nude mice. MC-1 cells, in contrast to normal equine dermal fibroblasts, exhibit all of the characteristics of malignantly transformed cells.

Spontaneous expression of an endogenous retrovirus by the equine sarcoid-derived MC-1 cell line.

A retrovirus is spontaneously released into the culture medium of the equine sarcoid-derived MC-1 cell line. The MC-1 virus did not exhibit in vitro transforming activity or replication when tested on equine fibroblasts or a variety of other mammalian cell cultures. Complementary DNA, synthesized using detergent-activated MC-1 virus RNA-dependent DNA polymerase, detected homologous sequences in the DNA of an established equine dermal cell line and in the DNA of primary equine dermal fibroblasts. Iododeoxyuridine or azacytidine induced a replication-deficient endogenous retrovirus in the normal fibroblasts and amplified the production of MC-1 virus by the tumor cells. It was concluded that the endogenous virus, repressed in normal equine cells, is spontaneously expressed by the tumor cells.

Electron-impact excitation out of the metastable levels of krypton.

We have measured the electron-impact excitation cross sections out of the two metastable levels of Kr into the ten levels of the 4p(5)5p configuration. For a common 4p(5)5p final level, the peak excitation cross sections out of the two individual 4p(5)5s metastable levels are found to differ by 1 to 2 orders of magnitude. This is explained by the special features of the electronic structure of the two configurations involved. The peak cross sections are 10 to 1600 times larger than the corresponding peak cross sections out of the ground state.

Measuring change in academic self-concept resulting from curricular and instructional innovations.

The paper begins with a discussion of the psychometric and psychological problems involved in attempts to measure changes in human characteristics. The Rasch psychometric model is proposed as a model which has the potential of alleviating or eliminating many of the problems. The model is applied to a set of responses to an academic self-concept instrument administered to seventh-, eighth-, and ninth-grade students. Items that failed to conform adequately to the model at every grade level were eliminated from the scale. The resulting scale was found to possess several properties which permitted its use in the measurement of school-induced change in academic self-concept.