Spectroscopic evidence of silica-lignin complexes: implications for treatment of non-wood pulp wastewater.

This research examined the hypothesis that lignin compounds form aqueous complexes with silica increasing its solubility, thereby inhibiting its precipitation. An experimental program using four lignin model compounds was conducted to test the hypothesis. Laser Raman spectroscopy (LRS) was used to characterize, qualitatively, the interaction between lignin and aqueous silica, and to identify the possibility of silica-lignin complexation. Solubility studies were then performed by analyzing the solubility of silica in presence and absence of lignin within the relevant pH range to confirm the results of LRS, and to obtain a quantitative assessment of the relative solubility. The findings have established the formation of silica-ferulic, silica-vanillic, and silica-4-methoxycinnamic acid complexes, but no evidence was detected for the formation of silica-veratryl alcohol complex. In fact, the black liquor undoubtedly contains much more complex lignin materials than the simple model compounds used in this work. The more complex lignin compounds are likely to have an even greater tendency to form silica complexes, thus contributing to the initial hypothesis. This finding provides a fundamental understanding as to why previous efforts to precipitate silica by lowering the pH from 10-11 (for black liquor) to less than 9 did not achieve satisfactory silica separation, and why alternative strategies need to be investigated.

Recommended design for more accurate duplication of natural conditions in salt marsh creation.

Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes ( Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function.

Simple mass balance approach for assessment of flood control sumps in an urban watershed: case study of heavy metal loading.

Levee sump systems are used by many riverine communities for temporary storage of urban wet weather flows. The complex hydraulics and transport of stormwater pollutants in sump systems, however, have not been systematically studied. The objective of this work is to present a case study, utilizing a relatively simple and low-cost methodology, for assessing the hydraulic performance of flood control sumps in an urban watershed. Two sumps of highly variable physical and hydraulic characteristics were selected for analysis. HEC-1 software was used to estimate the flow hydrograph for each outfall to a sump as part of the overall flow balance, resulting in a total runoff hydrograph for a precipitation event. To validate HEC-1 results, a water balance was used to estimate the total runoff using sump operational data. The results suggest that HEC-1 calculation provide a satisfactory estimate of the total runoff and its time-distribution to the sump. The hydraulic model was then used to estimate nonpoint loads of selected heavy metals to the sump and to the river. Although flow of stormwater through a sump system is regulated solely by flood-control requirements, these sumps may function as sedimentation basins that provide purification of stormwater. An example calculation of removal of heavy metals in a sump using a mass balance approach is presented.

Improved experimental limits on the production of magnetic monopoles.

We present new limits on low mass accelerator-produced pointlike Dirac magnetic monopoles trapped and bound in matter surrounding the D0 collision region of the Tevatron at Fermilab (experiment E-882). In the context of a Drell-Yan mechanism, we obtain cross section limits for the production of monopoles with magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac charge of the order of picobarns, some 100 times smaller than found in similar previous Fermilab searches. Mass limits inferred from these cross section limits are presented.

Heavy metal contaminants removal by soil washing.

The feasibility of soil washing for decontaminating a silty sand spiked with cadmium, chromium, lead, and zinc was evaluated in laboratory-scale batch and column experiments. Soil samples were subjected to chelant extraction using a solution of disodium salt of ethylenediaminetetraacetic acid (Na(2)EDTA), sodium metabisulfite (Na(2)S(2)O(5)) solution (an inexpensive reducing reagent), and a solution containing a mixture of the two reagents. Batch and column washing of the contaminated soil with deionized water (DI water) revealed that approximately 70% of the cadmium in the sample is weakly bound and readily mobilized in aqueous solution at neutral pH, followed by approximately 25%-30% of zinc, approximately 20%-25% chromium, and only approximately 10% of lead. Of the washing reagents tested, Na(2)EDTA solutions were generally more effective than Na(2)S(2)O(5) for removing heavy metals from the soil samples. Na(2)EDTA preferentially extracted lead over zinc and cadmium but exhibited little impact on chromium removal. Cadmium and, especially zinc, removal by a 0.01-M Na(2)EDTA solution were enhanced considerably by inclusion of 0.1 M Na(2)S(2)O(5), suggesting that a mixture of the two reagents may provide an economically optimum solution for certain contaminated soils.

5-HT induces cAMP production in crypt colonocytes at a 5-HT4 receptor.

Previous studies demonstrate that both 5-hydroxytryptamine (5-HT) and cyclic AMP (cAMP) induce chloride efflux from crypt colonocytes in the rat distal colon; antagonist studies suggest that the 5-HT response is mediated primarily by the 5-HT4 receptor. Since this receptor is known to be positively coupled to adenylate cyclase, we postulated that 5-HT should induce generation of cAMP, which should be inhibited by 5-HT4 antagonists. Method. Mucosal cells from rat distal colon were taken by a sequential calcium chelation technique for enrichment of crypt cells. Cytokeratin stains demonstrated that >99% of cells were colonocytes. [3H]Thymidine uptake studies demonstrate a fivefold increased incorporation in this cell preparation compared to earlier fractions. 3-Isobutyl-l-methylxanthine (IBMX, 100 microM) was added to all cell suspensions in order to prevent cAMP metabolism. Cell suspensions were incubated for 2 min at 37 degreesC with different concentrations of 5-HT (n = 7). cAMP was measured by enzyme immunoassay. In another series of experiments, 5-HT (0.3 microM) stimulation of cAMP was similarly measured in the presence and absence of 5-HT receptor antagonists: 10 microM 5-HTP-DP (5-HT1P; n = 4), 0.1 microM ketanserin (5-HT2A; n = 4), 0.3 microM ondansetron (5-HT3; n = 4), 3 microM tropisetron (5-HT3 and 5-HT4; n = 4), and 10 nM GR-113808 (5-HT4; n = 5). Results. 5-HT produced a dose-dependent increase in cAMP. The increase was significant at concentrations >/=0.3 microM when compared to cells incubated with IBMX alone. In the second series of experiment, 5-HT-induced generation of cAMP at a dose of 0.3 microM was significantly inhibited in the presence of GR-113808 and tropisetron. Conclusion. 5-HT acts at a 5-HT4 receptor to induce production of cAMP in rat distal crypt colonocytes.

Ambient but not incremental oxidant generation effects intercellular adhesion molecule 1 induction by tumour necrosis factor alpha in endothelium.

Proinflammatory cytokines upregulate endothelial adhesion molecule expression, thereby initiating the microvascular inflammatory response. We re-evaluated the reported role of reactive oxygen metabolites (ROMs) in signalling upregulation of intercellular adhesion molecule 1 (ICAM-1) on endothelial cells by tumour necrosis factor alpha (TNF-alpha) in vitro. TNF-alpha upregulation of endothelial-cell ICAM-1 expression was inhibited by the cell-permeable antioxidants, or by the adenovirus-mediated intracellular overexpression of Cu,Zn-superoxide dismutase, but not by the exogenous (extracellular) administration of the cell-impermeable antioxidants, superoxide dismutase and/or catalase. This ICAM-1 upregulation was also inhibited by inhibitors of NADH dehydrogenase, cytochrome bc1 complex and NADPH oxidase. However, a measurable increase in net cellular ROM generation in response to TNF-alpha was not seen using four disparate sensitive ROM assays. Moreover, the stimulation of exogenous or endogenous ROM generation did not upregulate ICAM-1, nor enhance ICAM-1 upregulation by TNF-alpha. These findings suggest that an ambient background flux of ROMs, generated intracellularly, but not their net incremental generation, is necessary for TNF-alpha to induce ICAM-1 expression in endothelium in vitro.

Protein tyrosine phosphorylation mediates TNF-induced endothelial-neutrophil adhesion in vitro.

Proinflammatory cytokines initiate the vascular inflammatory response via the upregulation of adhesion molecules on the luminal endothelial surface. We investigated directly the role of protein tyrosine phosphorylation in the upregulation of the endothelial adhesion molecules, intercellular adhesion molecule 1 (ICAM-1) and E-selectin, and the consequent adhesion of neutrophils, after tumor necrosis factor (TNF)-alpha-stimulation of human aortic endothelial cells in vitro. Time- and dose-dependent TNF-alpha-stimulated ICAM-1 and E-selectin upregulation and neutrophil adhesion each were suppressed by tyrosine kinase inhibitors, including genistein (200 microM), but not genistein, its isoflavone analog without tyrosine kinase inhibitory activity. Tyrphostin AG 126, a synthetic selective tyrosine kinase inhibitor, also suppressed ICAM-1 and E-selectin upregulation and neutrophil adhesion, each in a dose-dependent manner, whereas tyrphostin AG 1288 had no effect. Tyrosine phosphorylation of two proteins (85 and 145 kDa in the cytoskeleton fraction) found minutes after TNF-alpha-stimulation was also inhibited by genistein. These findings suggest that, in endothelial cells, TNF-alpha upregulates ICAM-1 and E-selectin expression and consequent neutrophil adhesion via protein tyrosine phosphorylation.

Role of reactive oxygen metabolites in murine peritoneal macrophage phagocytosis and phagocytic killing.

This study was designed to quantify the role of reactive oxygen metabolites (ROMs) in two distinct components of murine peritoneal macrophage activity, phagocytosis and killing, and to discriminate quantitatively the degree to which each component is dependent on NADPH oxidase and/or xanthine oxidase. A fluorochromatic vital staining technique was modified to simultaneously quantify phagocytosis and microbicidal activity of macrophages incubated with Candida parapsilosis targets. To determine the role of ROMs, macrophages were preincubated with free radical scavengers [superoxide dismutase (SOD) and/or catalase] or with selective inhibitors of xanthine oxidase (XO, e.g., allopurinol) or NADPH oxidase [diphenyleneiodonium (DPI)]. Phagocytosis was not affected by treatment of macrophages with SOD, catalase, allopurinol, or DPI. Candidacidal activity, however, was inhibited by SOD, allopurinol, or DPI. The inhibitory effects of DPI and allopurinol were additive. Histochemical and biochemical assays demonstrated substantial quantities of XO in murine peritoneal macrophages. The findings suggest that the generation of ROMs by XO- and NADPH oxidase-dependent pathways are each important for phagocytic killing by murine peritoneal macrophages.

Identification of a 5-hydroxytryptamine (5-HT2) receptor on guinea pig small intestinal crypt cells.

Radioligand labeling of [3H]ketanserin was examined in suspensions of dispersed guinea pig small intestinal mucosal cells prepared by modification of the EDTA-chelation method described by M. M. Weiser (J. Biol. Chem. 248: 2536-2541, 1973). Preferential incorporation of [3H]thymidine was used to confirm that suspensions were enriched in crypt cells. At 25 degrees C, binding of [3H]ketanserin to dispersed enterocytes was rapid, maximal by 5 min, saturable (dissociation constant = 1.5 nM), 65 +/- 5% specific, stable, and reversible. The maximal number of binding sites per cell was 92,000 (range 86,000-105,500). Binding was temperature dependent, with maximal binding at 37 degrees C, and was inhibited by 5-hydroxytryptamine (5-HT) (half-maximal inhibition of [3H]ketanserin binding observed in response to 1 microM 5-HT) and ketanserin (half-maximal inhibition of [3H]ketanserin binding observed in response to 1 nM ketanserin) but not by the 5-HT1P antagonist N-acetyl-5-hydroxytryptophyl 5-hydroxytryptophan amide (5-HTP-DP) or the 5-HT3 antagonist 3-tropanyl-indole-3-carboxylate methiodide (ICS-205-930). The second messenger system coupled to the putative mucosal 5-HT2 receptor was examined. 5-HT stimulated a concentration-dependent production of inositol 1,4,5-trisphosphate (IP3) in the dispersed enterocytes. This was maximal at 1 min and was inhibited in a concentration-dependent manner by ketanserin. 5-HTP-DP and ICS-205-930 had no effect on 5-HT-stimulated production of IP3. These data provide evidence for the existence of a mucosal 5-HT2 receptor located on guinea pig small intestinal crypt cells.

Induction of heat shock response leads to apoptosis in endothelial cells previously exposed to endotoxin.

The homeostatic response of complex eukaryotes to the challenge of environmental stress includes the induction of several programs of gene expression; among them are those for the acute phase genes and those for the heat shock genes. In some systems, the heat shock response, which is often elicited by more severe stimuli, preempts the acute phase response, which is seen in response to less severe challenges, as well as constitutive gene expression. Nevertheless, each response appears to provide a natural selective advantage for survival of the organism in a toxic environment. However, when cultured porcine endothelial cells were exposed first to a nonlethal level of bacterial endotoxin lipopolysaccharide (LPS), an inducer of the acute phase response, and then, simultaneously to standard stimuli, which normally elicit a salutary heat shock response, the cells died manifesting a pattern of DNA fragmentation (nucleolysis) characteristic of programmed cell death (apoptosis). The treatment of LPS-exposed cells with cycloheximide to block protein synthesis reproduced the lethal apoptosis that had been elicited by the induction of heat shock gene expression. Therefore, the preemption of other programs of stress gene expression by the prioritized expression of heat shock genes is associated with apoptosis.

Synthesis and use of the n-bromododecane-1,12-diols as conformational probes for general anesthetic target sites.

The n-bromododecane-1,12-diols with bromine on carbons 2, 3, 5, and 6, respectively, were synthesized and found to be potent general anesthetics. They were also found to be potent inhibitors of firefly luciferase, a protein model for the primary target sites underlying general anesthesia. However, their effects on lipid bilayers were small, lowering the chain-melting phase transition temperature by less than 1 degree C at their EC50 concentrations for general anesthesia. A large dependence upon the position of the bromine atom was found for both n-hexadecane/water partition coefficients and inhibition constants for firefly luciferase; a much smaller positional dependence was found for induction of general anesthesia and for disrupting lipids. These results are consistent with the bulky bromine atom inhibiting the conformational flexibility of the diol hydrocarbon chain, making these bromo diols useful probes for ascertaining the shapes of apolar binding sites. In particular, our measurements suggest that these novel anesthetics produce general anesthesia by binding to long and relatively narrow apolar target sites in the central nervous system.

A double-blind, multicenter comparison of 0.05% halobetasol propionate ointment and 0.05% clobetasol propionate ointment in patients with chronic, localized plaque psoriasis.

In a double-blind, parallel-group, multicenter trial in 134 patients with severe, localized, plaque psoriasis, the success rate (described as "healed" or "marked improvement") at the end of the study was 96% in the halobetasol propionate group and 91% in the clobetasol propionate group. A significantly larger proportion of patients treated with halobetasol had no disease or mild disease after 14 days compared with those treated with clobetasol (86% versus 70%, p = 0.023). Healing within 24 days of starting treatment was noted in 69% and 56% of patients treated with halobetasol and clobetasol, respectively. Adverse effects were reported in a smaller percentage of patients treated with halobetasol propionate ointment than in those treated with clobetasol propionate ointment (7% versus 12%). Cosmetic acceptability and ease of application were recorded as "very good" in a larger percentage of patients treated with halobetasol propionate ointment than in the group treated with clobetasol propionate (90% versus 80%).

Complications of percutaneous abdominal fine-needle biopsy. Review.

To determine whether the increasing use of percutaneous fine-needle biopsy of abdominal lesions is associated with an increase in serious complications, the author updated a literature search and evaluated a questionnaire (distributed among selected hospitals in the United States in 1986 and 1987) that followed up a questionnaire distributed in 1983. The updated literature review revealed a total of 24 deaths and 20 needle tract seedings. The updated questionnaire revealed five deaths after 16,381 biopsies (0.031%), whereas the previous questionnaire had shown four deaths after 63,108 biopsies (0.006%). Two similar European questionnaires revealed mortality rates of 0.008% and 0.018%, respectively. Of the total of 33 deaths, 21 involved biopsies of liver lesions; six involved pancreatic biopsies. Seventeen of the 21 deaths after liver biopsies were secondary to hemorrhage; five of the six deaths after pancreatic biopsies were due to pancreatitis. Of the 23 instances of needle tract seeding, 10 occurred after biopsies of pancreatic malignancies. The frequencies of needle tract seeding in the four questionnaires were 0.005%, 0.006%, 0.003%, and 0.009%, respectively. Although infrequent, serious complications may be associated with this procedure. The author makes suggestions that may help minimize them.

CT of the pancreas with a fat-density oral contrast regimen.

Visualization of the head of the pancreas by CT was prospectively evaluated in two groups of 100 patients who did not have pancreatic disease. Patients were given either a fat-density oral contrast material (12.5% corn-oil emulsion and metoclopramide) or a conventional high-density oral contrast material (barium suspension or iodinated solution). There was no statistically significant difference in the subjects' tolerance to the two regimens. There was, however, a significant improvement in ability to distinguish the head of the pancreas from the duodenal C-loop when the fat-density contrast material was given. When pancreaticoduodenal discrimination was graded, patients given corn-oil emulsion and metoclopramide received an average score of 0.94, whereas those given the high-density agent received an average score of 0.74, with 1.00 being the highest possible score (p less than .005). These data suggest that for routine CT evaluation of the head of the pancreas, a combination of corn-oil emulsion and metoclopramide may be superior to the conventional high-density oral contrast agents given without metoclopramide.

Beta-adrenoceptors on duodenal mucosal cells mediate venous serotonin release.

We have previously documented predominant intraluminal release of serotonin (5-HT) following activation of muscarinic receptors on enterochromaffin cells. Gronstad et al. reported that portal venous release of 5-HT in response to vagal stimulation was mediated by beta-adrenergic receptors. The purpose of this study was to determine whether 5-HT release induced by the beta-adrenergic agonist, isoproterenol, is mediated by enteric nerves or is a direct action at the enterochromaffin cell level. We mounted rabbit duodenal mucosal sheets stripped of muscularis in modified Ussing chambers and measured release of 5-HT in response to 10(-5) M isoproterenol, in the presence and absence of the neural conduction blocker tetrotoxin, 10(-6) M. Serotonin was measured in the buffer bathing the mucosal and submucosal surfaces by HPLC. In the presence of isoproterenol, total (mucosal and submucosal) 5-HT release (21.0 +/- 4.9 ng/cm2/45 min) was significantly (P less than 0.05) greater than that in untreated controls (7.8 +/- 2.7 ng/cm2/45 min); release was predominantly toward the submucosal surface. In the presence of tetrodotoxin alone, net 5-HT release was significantly (P less than 0.05) increased to 12.8 +/- 2.8 ng/cm2/45 min. In tetrodotoxin-treated mucosa, isoproterenol increased 5-HT release to 28.6 +/- 5.3 ng/cm2/45 min which was significantly greater (P less than 0.05) than that with tetrodotoxin alone. Since 5-HT release was increased even in the presence of neural blockade, these results suggest that activation of beta-adrenergic receptors on or near enterochromaffin cells induces release of 5-HT predominantly toward the submucosal surface.

Clinicians' appraisal of sonography.

The perceived efficacy of sonography in making diagnostic and management decisions in clinical practice was determined through a questionnaire survey of physicians who had recently referred patients to a university radiology department. Of 2,178 questionnaires sent, 1,611 were returned (74%). Sensitivity and specificity of sonography, corrected for verification bias, were 72% and 84%. Referring physicians considered the studies to be of value in arriving at the final diagnosis and in the clinical management of patients in approximately two-thirds of the cases. Results were considered of no value and misleading in 4% of the cases. Sonography was more accurate and was reported to be valuable by approximately 10% more physicians when a specific indication for an examination could be identified rather than when indications were vague and when sonographic findings were abnormal rather than normal (P less than .005). In general, sonography was of equal value to both specialists and nonspecialists. The results of this study suggest that sonography is, and is perceived by clinicians to be, an accurate and valuable clinical diagnostic modality.