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PubMed2001

Charge-reduced nano electrospray ionization combined with differential mobility analysis of peptides, proteins, glycoproteins, noncovalent protein complexes and viruses.

This study explores the potential of a novel electrospray-based method, termed gas-phase electrophoretic mobility molecular analysis (GEMMA), allowing the molecular mass determination of peptides, proteins and noncovalent biocomplexes up to 2 MDa (dimer of immunglobulin M). The macromolecular ions were formed by nano electrospray ionization (ESI) in the 'cone jet' mode. The multiple charged state of the monodisperse droplets/ions generated was reduced by means of bipolar ionized air (generated by an alpha-particle source) to yield exclusively singly charged positive and negative ions as well as neutrals. These ions are separated subsequently at atmospheric pressure using a nano differential mobility analyzer according to their electrophoretic mobility in air. Finally, the ions are detected using a standard condensation particle counter. Data were expressed as electrophoretic mobility diameters by applying the Millikan equation. The measured electrophoretic mobility diameters, or Millikan diameters, of 32 well-defined proteins were plotted against their molecular weights in the range 3.5 to 1920 kDa and exhibited an excellent squared correlation coefficient (r(2) = 0.999). This finding allowed the exact molecular weight determination of large (glyco)proteins and noncovalent biocomplexes by means of this new technique with a mass accuracy of +/-5.6% up to 2 MDa at the femtomole level. From the molecular masses of the weakly bound, large protein complexes thus obtained, the binding stoichiometry of the intact complex and the complex stability as a function of pH, for example, can be derived. Examples of specific protein complexes, such as the avidin or catalase homo-tetramer, are used to illustrate the potential of the technique for characterization of high-mass biospecific complexes. A discussion of current and future applications of charge-reduced nano ESI GEMMA, such as chemical reaction monitoring (reduction process of immunglobulin G) or size determination of an intact virus, a supramolecular complex, and monitoring of partial dissociation of a human rhinoviruses, is provided.

Electrophoresis↗
PubMed2002

Feasibility of mobile cancer screening and prevention.

Many areas have high cancer mortality rates and medically underserved populations. This study describes the feasibility (acceptability and costs) of an urban multiphasic (multiple cancers) screening van. Feasibility was evaluated by literature review and informant interviews. Costs were estimated by resource use from urban mobile screening units; decision analysis estimated the costs per cancer detected for breast, cervix, colorectal, and prostate cancer screening. Acceptability of a multiphasic van varied by the informant's perspective. Feasibility and costs were most sensitive to four parameters: age, prior screening history, risk factors, and volume of simultaneous examinations. Subsidized mobile screening facilities may have the potential to reduce cancer morbidity and mortality if they target hard-to-reach underscreened groups, maintain high volume, coordinate with primary care providers, and build on an infrastructure that provides diagnostic and treatment services regardless of ability to pay. It is unclear whether the investment required will translate into a reasonable cost per year of life saved.

Cost-Benefit Analysis↗
PubMed2001

A computer model of an image intensifier system working under automatic brightness control.

A computer model of a fluoroscopy unit operating under automatic brightness control has been developed. The model has been validated by simulating one particular unit but is very general in nature and can easily be applied to other fluoroscopy systems. The model was developed by breaking the operation of a fluoroscopy unit down into its constituent parts then implementing each part in a module of code. It is controlled using the input air kerma to the intensifier face. Discrepancies from the situation when the model is controlled by the energy deposited in the input phosphor have been investigated and shown to be negligible over the operating range. To calculate entrance surface dose rates (ESDRs) to water and polymethylmethacrylate (PMMA) phantoms, Monte Carlo techniques were used to generate backscatter factors for these materials using the beam geometry and range of possible tube potentials and field sizes of a typical mobile image intensifier unit. The model was validated by calculating ESDRs to different thicknesses of water and PMMA phantoms. The predictions generated by the model were in good agreement with experimental measurements. Potential uses of the model include evaluation of dose reduction techniques, investigation of the balance between patient dose and image quality, and assessment of scatter dose.

Algorithms↗
PubMed2002

TreeDock: a tool for protein docking based on minimizing van der Waals energies.

Predicting protein-protein and protein-ligand docking remains one of the challenging topics of structural biology. The main problems are (i) to reliably estimate the binding free energies of docked states, (ii) to enumerate possible docking orientations at a high resolution, and (iii) to consider mobility of the docking surfaces and structural rearrangements upon interaction. Here we present a novel algorithm, TreeDock, that addresses the enumeration problem in a rigid-body docking search. By representing molecules as multidimensional binary search trees and by exploring a sufficient number of docking orientations such that two chosen atoms, one from each molecule, are always in contact, TreeDock is able to explore all clash-free orientations at very fine resolution in a reasonable amount of time. Due to the speed of the program, many contact pairs can be examined to search partial or complete surface areas. The deterministic systematic search of TreeDock is in contrast to most other docking programs that use stochastic searches such as Monte Carlo or simulated annealing methods. At this point, we have used the Lennard-Jones potential as the only scoring function and show that this can predict the correct docked conformation for a number of protein-protein and protein-ligand complexes. The program is most powerful if some information is known about the location of binding faces from NMR chemical-shift perturbation studies, orientation information from residual dipolar coupling, or mutational screening. The approach has the potential to include docking-site mobility by performing molecular dynamics or other randomization methods of the docking site and docking families to families of structures. The performance of the algorithm is demonstrated by docking three complexes of immunoglobulin superfamily domains, CD2 to CD58, the V(alpha) domain of a T-cell receptor to its V(beta) domain, and a T-cell receptor to a pMHC complex as well as a small molecule inhibitor to a phosphatase.

Algorithms↗
PubMed1999

Electrophysiological and ultrastructural correlates of cryoinjury in sciatic nerve of the freeze-tolerant wood frog, Rana sylvatica.

We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at -2.5 degrees C, -5.0 degrees C, or -7.5 degrees C. All frogs frozen at -2.5 degrees C, and most frogs (71%) frozen at -5.0 degrees C, recovered within 14 h after thawing began; however, frogs did not survive exposure to -7.5 degrees C. Sciatic nerves isolated from frogs frozen at -7.5 degrees C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to -2.5 degrees C or -5.0 degrees C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at -2.5 degrees C or -5.0 degrees C had little or no effect on tissue and cellular organization, but that (lethal) exposure to -7.5 degrees C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.

Action Potentials↗
PubMed1997

Mobilization and transplantation of Philadelphia-negative peripheral-blood progenitor cells early in chronic myelogenous leukemia.

PURPOSE: Mobilization of Philadelphia (Ph) chromosome-negative progenitors is now possible in many Ph1-positive chronic myelogenous leukemia (CML) patients who had received interferon alfa (IFN-alpha) with no cytogenetic response. In this pilot study, we used this approach in patients without prior IFN-alpha therapy to determine if the number and quality of mobilized progenitors would be increased and to evaluate the potential effect of these cells as autografts. PATIENTS AND METHODS: Twenty-two untreated patients were mobilized within 12 months of diagnosis. The treatment regimen consisted of the mini-ICE protocol. Beginning on day +8, granulocyte colony-stimulating factor (G-CSF) was used in all patients. Leukophoresis was performed as the patients were recovering from aplasia, when WBC count exceeded 0.8 x 10(9)/L. RESULTS: In 14 patients, (63%) the leukophoresis product was entirely Ph1-negative and in four patients the Ph1-positive cell rate was < or = 7%. Significant numbers of long-term culture-initiating cells (LTC-IC) and CD34+ Thy1+Lin- cells were found in most of the Ph1-negative collections that were tested. Twelve patients underwent autografting with their mobilized peripheral-blood progenitor cells (PBPC) (Ph1-negative collections, 10 patients; major cytogenetic response, two patients). All patients engrafted and are alive; six have Ph1-negative marrow 7 to 15 months after autografting. Posttransplant treatment was IFN-alpha combined with interleukin (IL)-2 because of the recent demonstration of synergistic activity in augmenting cytolytic activity. CONCLUSION: Intensive chemotherapy given in early chronic phase of CML is well tolerated and results in high numbers of circulating Ph1-negative precursor cells.

Adult↗
PubMed2001

Mobility impairments in crash-involved older drivers.

OBJECTIVE: To evaluate potential associations of impairments in physical function with motor vehicle crash involvement in older drivers. METHODS: Case participants were randomly selected residents of Mobile County, Alabama, greater or less than 65 years old who had sustained an at-fault motor vehicle crash in 1996. Similarly selected crash-free controls were frequency matched to cases on gender and age. Self-report data on demographic variables, medical conditions, medications, driving exposure, and function were collected by telephone interviewers. RESULTS: Relative to crash-free subjects, crash-involved drivers were significantly more likely to report difficulty walking one fourth mile and moving outdoors. Marginally significant associations were observed for trouble carrying a heavy object 100 yards and for the occurrence of falls in the prior year. Increasing numbers of functional limitations were directly related to the odds of crash involvement. DISCUSSION: In comparison to crash-free controls, crash-involved older drivers are more likely to report other mobility-related impairments, possibly including falls.

Accidental Falls↗
PubMed2004

Making more heart muscle.

Postnatally, heart muscle cells almost completely lose their ability to divide, which makes their loss after trauma irreversible. Potential repair by cell grafting or mobilizing endogenous cells is of particular interest for possible treatments for heart disease, where the poor capacity for cardiomyocyte proliferation probably contributes to the irreversibility of heart failure. Knowledge of the molecular mechanisms that underly formation of heart muscle cells might provide opportunities to repair the diseased heart by induction of (trans) differentiation of endogenous or exogenous cells into heart muscle cells. We briefly review the molecular mechanisms involved in early development of the linear heart tube by differentiation of mesodermal cells into heart muscle cells. Because the initial heart tube does not comprise all the cardiac compartments present in the adult heart, heart muscle cells are added to the distal borders of the tube and within the tube. At both distal borders, mesodermal cell are recruited into the cardiac lineage and, within the heart tube, muscular septa are formed. In this review, the relative late additions of heart muscle cells to the linear heart tube are described and the potential underlying molecular mechanisms are discussed.

Animals↗
PubMed2005

Changes of chromium behavior in soil during phenanthrene removal by Penicillium frequentans.

Soil contamination due to polycyclic aromatic hydrocarbons is often associated with the presence of high levels of potentially toxic metals. Bioremediation is an important option for the clean up of this type of contamination. Changes of chromium fluxes and concentrations during the phenanthrene removal by Penicillium frequentans in soil were investigated. During the bioremediation process, changes in chromium behavior were monitored by Diffusive Gradients in Thin-films (DGT) and by filtration in both sterilized and non-sterilized soils. DGT provided absolute data on fluxes from the solid phase and relative trends of concentrations of the most labile metal species. Filtration provided data on the concentrations of Cr in the solution phase. Together the data provided information about the physical and chemical metal behavior. Results showed that the highest phenanthrene removal was observed in non-sterilized soil (which included the autochthonous microorganisms and P. frequentans inoculum), with a phenanthrene removal of 73 +/- 3.2%. However, in all cases microbial activity increased chromium fluxes and chromium soil solution concentration. The bioremediation of soil by P. frequentans increased the lability and mobility of chromium in soil, with potential consequences for plant uptake and for increased movement of metals into the human food chain.

Biodegradation, Environmental↗
PubMed2005

The McbR repressor modulated by the effector substance S-adenosylhomocysteine controls directly the transcription of a regulon involved in sulphur metabolism of Corynebacterium glutamicum ATCC 13032.

In a recent proteomics study we have shown that the mcbR gene of Corynebacterium glutamicum ATCC 13032 most probably encodes a transcriptional repressor of the TetR type, which regulates the expression of at least six genes involved in the synthesis of sulphur-containing amino acids. By means of DNA microarray hybridizations we detected 86 genes with enhanced transcription in an mcbR mutant when compared with the wild-type strain. Bioinformatic analysis identified the inverted repeat 5'-TAGAC-N6-GTCTA-3' as a consensus sequence within the upstream region of 22 genes and operons, suggesting that the transcription of at least 45 genes is directly controlled by the McbR repressor. These 45 genes encode a variety of functions in (S-adenosyl)methionine and cysteine biosynthesis, in sulphate reduction, in uptake and utilization of sulphur-containing compounds and in transcriptional regulation. The function of the inverted repeat motif as potential McbR binding site in front of the genes hom, cysI, cysK, metK and mcbR was verified experimentally by competitive electrophoretic mobility shift analysis. A systematic search for the potential effector substance modulating the function of McbR revealed that only S-adenosylhomocysteine prevented the binding of McbR to its target sequence. These results indicate that the transcriptional repressor McbR directly regulates a set of genes comprising all aspects of transport and metabolism of the macroelement sulphur in C. glutamicum. As the activity of McbR is modulated by S-adenosylhomocysteine, a major product of transmethylation reactions, the results point also to a novel regulatory mechanism in bacteria to control the biosynthesis of S-adenosylmethionine.

Bacterial Proteins↗
PubMed1998

The influence of patient-related factors on ex vivo retroviral-mediated gene transfer into mobilized peripheral blood myeloid progenitors.

Mobilized human peripheral blood progenitor cells are potential alternatives to bone marrow cells as targets for ex vivo gene transfer. We report the transduction efficiency of retroviral-mediated gene transfer into myeloid progenitors of peripheral blood progenitor cell (PBPC) harvests, mobilized by high-dose cyclophosphamide and GM-CSF, compared with nonmobilized bone marrow (BM). Eleven PBPC samples were enriched for CD34+ cells, preincubated with IL-3 (10 ng/ml), IL-6 (50 ng/ml), and 10% autologous plasma for 42 hr, and transduced over a 6-hr incubation with IL-3 + IL-6 and a retroviral vector carrying the NeoR gene. NeoR-specific sequences were detected by polymerase chain reaction in 10 cell pellets (91%). Gene expression in CFU-GM colonies was found in nine transduced samples (82%), with a mean transduction efficiency of 5.2% (95% CI, 1.3-11.8%) CFU-GM per PBPC sample. In univariate analysis, a higher transduction efficiency into CFU-GM correlated significantly with a higher CFU-GM concentration in the CD34+-enriched sample (p = 0.009), a shorter interval from diagnosis (p < 0.001), and fewer months of prior cytotoxic treatment (p = 0.001); correlation with younger age was of borderline statistical significance (p = 0.077). In multivariate analysis a shorter interval from diagnosis and, to a lesser degree, a higher CFU-GM concentration in the CD34+-enriched sample were independent predictors of higher transduction efficiency. Twelve BM samples were similarly transduced; 11 pellets were PCR positive. CFU-GM NeoR gene expression was 4.2% (95% CI, 2.0-7.2%) CFU-GM per BM sample, which was not significantly different from the transduction efficiency into PBPC cells. No correlation was found between the transduction efficiency of CFU-GM in BM samples and CFU-GM concentration in the CD34+-enriched sample, time from diagnosis, months of prior cytotoxic treatment, and/or patient age. Our data suggest that the transduction efficiency ex vivo may be influenced by time from diagnosis, CFU-GM concentration in the sample, and possibly by the extent of prior cytotoxic administration.

Adult↗
PubMed1976

Synaptic depression at a synapse in Aplysia californica: analysis in terms of a material flow model of neurotransmitter.

When a pair of stimuli separated by an appropriate interval is given to the right visceropleural connective of Aplysia californica the amplitude of the second EPSP elicited in cell R15 is usually smaller than the amplitude of the first EPSP. In the present paper we show that this phenomenon, synaptic depression, can be analyzed in terms of the material flow model of neurotransmitter economics developed in our preceding publications. We specifically show how changes in the 4 model parameters; A, the available pool of transmitter; F, the fraction of the available pool released by a presynaptic action potential; M, the rate of transmitter mobilization into the available pool; and D, the rate constant of demobilization of transmitter from the available pool, all effect synaptic depression. In addition, we show how transient changes in F and M, that are observed immediately and for seconds after a stimulus, influence the time course of synaptic depression. Using this analysis we then tested our previous inferences about changes in the model parameters produced either by pharmacological manipulations or repetitive stimulation, by comparing the observed effects of these manipulations on synaptic depression with the theoretical predictions. The theoretical and experimental findings agreed, thereby strengthening both our previous conclusions of the mode of action of these manipulations and the model itself.

Animals↗
PubMed2004

NFATc1 activates the acetylcholinesterase promoter in rat muscle.

Nuclear factor of activated T-cells (NFAT) plays a role in the response of muscle to chronic contractile activity that can result in fiber type switching and hypertrophy. These effects are due in part to activation of target genes following Ca2+-mediated nuclear translocation of NFAT. Acetylcholinesterase (AChE), a component of the neuromuscular junction, is regulated by chronic muscle and nerve activity through changes in intracellular Ca2+, suggesting that the Ache gene may be a potential downstream target of NFAT signaling. To determine whether elements of the Ache promoter are modulated by NFAT, we transiently co-expressed reporter constructs driven by fragments of the Ache promoter with an NFATc1 that is constitutively translocated to the nucleus [NFATc1(S --> A)] in rat muscle cultures. NFATc1 potentiated reporter activity when co-transfected with constructs containing Ache genomic elements from -1280 to -490 bp upstream of transcription initiation. Electrophoretic mobility shift assays demonstrated strong binding to a potential NFAT element at -793 bp and weaker binding to one at -678 bp. Co-transfection of promoter fragments, containing the binding sites at -793 and at -678 bp, with NFATc1(S --> A) potentiated reporter activity, supporting sites of interaction with NFAT. Our data suggests a role for NFAT as a modulator of Ache gene transcription.

Acetylcholinesterase↗
PubMed1987

[Bupivacaine and mepivacaine on artificial lipid membranes. A comparison of physicochemical parameters].

Mepivacaine and bupivacaine, frequently used local anesthetics, differ in a variety of clinical effects but show only small differences in chemical structure. In order to learn more about molecular mechanisms of action, we investigated the effects of these two local anesthetics on artificial membranes and liposomes. Methods. Artificial membranes were formed from dipalmitoylphosphatidylcholine - cholesterol or from a phospholipid mixture extracted from rabbit heart to separate into two aqueous phases (100 mM NaCl, 1 mM glycine, pH 7.4). Membrane current and potential were recorded after addition of local anesthetics on one side of the membrane. Electrophoretic mobility of liposomes, formed from phosphatidylcholine and a mixture of phosphatidylcholine with phosphatidylinositol, was measured by laser Doppler techniques. The surface potential (zeta potential) was calculated by Gouy-Chapman theory. Lipid/buffer partition coefficients were determined in phosphatidylcholine liposomes by centrifugation and spectrophotometric measurement of the concentration. Results. Mepivacaine and bupivacaine induce concentration-dependent electrostatic potentials on artificial membranes, resulting from incorporation of the charged drug form. Bupivacaine is more active than mepivacaine. The time of onset is short for mepivacaine and delayed for bupivacaine. The effects are retarded in the presence of glucose and are higher and more rapid for the carbonized form of bupivacaine (CO2 form instead of hydrochloride form). The electrostatic surface potential, measured by electrophoretic liposome mobility, is changed by the local anesthetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Bupivacaine↗
PubMed1991

Pharmacological evidence for the possible involvement of repetitive action potentials in facilitation by GABA of catecholamine secretion in bovine adrenal chromaffin cells.

1. gamma-Aminobutyric acid (GABA) evokes catecholamine (CA) secretion and enhances the stimulation-evoked CA secretion via facilitation of Ca2+ entry in a Cl(-)-dependent manner. The present study was designed to investigate further the ionic mechanism of modulation by GABA of CA secretion from adrenal medulla, using a primary culture of bovine chromaffin cells. 2. Tetrodotoxin (TTX), a voltage-sensitive Na+ channel blocker, reduced GABA-evoked CA secretion. 3. Inhibition of the sodium pump by ouabain or removal of extracellular K+ enhanced GABA-evoked CA secretion in a TTX-sensitive manner. 4. Tetraethylammonium (TEA) and cesium, which are known to block some types of K+ channels, markedly enhanced GABA-evoked CA secretion in a concentration-related fashion. TEA-induced enhancement of the GABA-evoked CA secretion was attenuated by TTX or replacement of extracellular Na+ by choline. On the other hand, ouabain accelerated the effect of TEA. 5. TEA and ouabain also enhanced GABA-induced Ca2+ influx and accumulation of cytosolic Ca2+, assessed with 45Ca2+ uptake and quin2 fluorescence. 6. Veratridine increased accumulation of cytosolic Ca2+ in a TTX-sensitive manner. GABA facilitated the veratridine-induced elevation of cytosolic Ca2+ even when the GABA-induced rise of cytosolic Ca2+ levelled off. 7. These results suggest the involvement of repetitive action potentials in modulation of GABA by Ca2+ mobilization and, as a consequence, of the CA secretion in chromaffin cells.

Action Potentials↗
PubMedDate not supplied

Escaping the box: preparing allied health practitioners for management positions.

Career ladders designed for health care practitioners are not always long enough to reach beyond the top rungs of clinical practice. Limited upward mobility can result in dissatisfaction and potential loss of experienced staff members. The same skills that allow practitioners to function successfully in patient care can be tapped into to prepare clinicians to move upward in administrative positions. This has already occurred successfully in the nursing profession. Managers should take advantage of the yearly performance evaluation to identify those health professionals who are interested in advancement. Using a strengths, weakness, opportunities, and threats analysis, the manager and clinician can work together to develop a developmental plan that will build on existing strengths while developing the less prepared areas. Managerial skill enhancement should be combined with mentoring from persons already filling administrative roles to enable the clinician to develop a network of contacts. A planned approach should enable interested clinicians to successfully transition from hands-on practice into managerial positions.

Allied Health Personnel↗
PubMed1995

[Pulmonary embolism and thrombi of the right heart].

In general, there are two types of right heart thrombi diagnosed by echocardiography: mobile and non-mobile thrombi, more often located in the atrium than in the ventricle and a potential source of pulmonary embolism. However, they differ in several points: clinical context, clinical and echocardiographic presentations, embolic potential, prognosis and treatment. The result of peripheral venous thrombosis, mobile thrombus it is usually diagnosed during echocardiographic investigation of pulmonary embolism. The appearances are often that of serpentine thrombus floating in the right heart chambers associated with signs of acute cor pulmonale. It is a marker of imminent and often fatal embolism as it completes a previous and usually severe pulmonary embolism; the mortality is over 40%. It is a contra-indication for pulmonary angiography because of the risk of embolism and a therapeutic emergency. Some groups advocate surgical embolectomy and others thrombolysis. Its precise frequency in the acute stage of pulmonary embolism and its treatment remain to be determined by a prospective, multicentre clinical trial. The adherent non-mobile thrombus is usually implanted on the free wall of the right atrium or the interatrial septum. Its formation, in situ, is due to stasis secondary to decompensated congenital or acquired cardiac disease or to the presence of an intracardiac foreign body such as a pacing wire. It is less likely to cause pulmonary embolism. It decreases or disappears with anticoagulant therapy and the outcome is usually good. The differential diagnosis between a mobile thrombus and a Chiari network, or between an adherent thrombus and a vegetation on a intracardiac pacing wire may be difficult and requires transoesophageal echocardiography. The investigation of pulmonary embolism requires systematic echocardiography, one of the objectives of which is to search for right sided thrombi.

Anticoagulants↗
PubMed2003

Toxicity of aqueous and sediment-associated fluoride to freshwater organisms.

Inorganic fluorides were declared toxic under the Canadian Environmental Protection Act in 1993 based on their potential to cause long-term harmful effects in aquatic and terrestrial ecosystems, but information on the toxicity of sediment-associated fluoride to freshwater benthic organisms was considered incomplete. The purpose of this study was to determine the toxicity of aqueous and sediment-associated fluoride to several species of freshwater organisms and to determine if toxic effects could be expected under environmentally realistic exposures. Toxicity of fluoride (as NaF) in short-term (48-96-h) lethality tests was greatest for the amphipod Hyalella azteca (median lethal concentration [LC50] = 14.6 mg F-/L), followed by the mayfly Hexagenia limbata (32.3), the midge Chironomus tentans (124.1), the fathead minnow Pimephales promelas (262.4), and the cladoceran Daphnia magna (282.8). Relative toxicity in long-term (10-28-d) growth and survival tests in spiked sediment was similar. Hyalella azteca was the most sensitive species for growth (25% inhibitory concentration [IC25] = 290.2 microg F-/g), followed by C. tentans (661.4), H. limbata (1,221.3), and P. promelas (>5,600); H. azteca was also the most sensitive species for survival (LC50 = 1,114.6 microg F-/g), followed by H. limbata (1,652.2) and P. promelas and C. tentans (>5,600 for both). Concentrations of fluoride measured in sediments near some industrial point sources exceed some of these toxicity thresholds. Fluoride is highly mobile in aquatic systems and could potentially reach toxic levels in the water column during dredging to remove fluoride-contaminated sediment.

Amphipoda↗