The effect of surface charge, negative and bipolar ionization on the deposition of airborne bacteria

AIMS

A series of experiments were conducted to evaluate the effect of surface charge and air ionization on the deposition of airborne bacteria.

METHODS AND RESULTS

The interaction between surface electrostatic potential and the deposition of airborne bacteria in an indoor environment was investigated using settle plates charged with electric potentials of 0, +/-2.5kV and +/-5kV. Results showed that bacterial deposition on the plates increased proportionally with increased potential to over twice the gravitational sedimentation rate at +5kV. Experiments were repeated under similar conditions in the presence of either negative or bipolar air ionization. Bipolar air ionization resulted in reduction of bacterial deposition onto the charged surfaces to levels nearly equal to gravitational sedimentation. In contrast, diffusion charging appears to have occurred during negative air ionization, resulting in an even greater deposition onto the oppositely charged surface than observed without ionization.

CONCLUSIONS

Static charges on fomitic surfaces may attract bacteria resulting in deposition in excess of that expected by gravitational sedimentation or simple diffusion. Implementation of bipolar ionization may result in reduction of bacterial deposition.

SIGNIFICANCE AND IMPACT OF STUDY

Fomitic surfaces are important vehicles for the transmission of infectious organisms. This study has demonstrated a simple strategy for minimizing charge related deposition of bacteria on surfaces.

Key residues controlling binding of diverse ligands to human cytochrome P450 2A enzymes

Although the human lung cytochrome P450 2A13 (CYP2A13) and its liver counterpart cytochrome P450 2A6 (CYP2A6) are 94% identical in amino acid sequence, they metabolize a number of substrates with substantially different efficiencies. To determine differences in binding for a diverse set of cytochrome P450 2A ligands, we have measured the spectral binding affinities (K(D)) for nicotine, phenethyl isothiocyanate (PEITC), coumarin, 2'-methoxyacetophenone (MAP), and 8-methoxypsoralen. The differences in the K(D) values for CYP2A6 versus CYP2A13 ranged from 74-fold for 2'-methoxyacetophenone to 1.1-fold for coumarin, with CYP2A13 demonstrating the higher affinity. To identify active site amino acids responsible for the differences in binding of MAP, PEITC, and coumarin, 10 CYP2A13 mutant proteins were generated in which individual amino acids from the CYP2A6 active site were substituted into CYP2A13 at the corresponding position. Titrations revealed that substitutions at positions 208, 300, and 301 individually had the largest effects on ligand binding. The collective relevance of these amino acids to differential ligand selectivity was verified by evaluating binding to CYP2A6 mutant enzymes that incorporate several of the CYP2A13 amino acids at these positions. Inclusion of four CYP2A13 amino acids resulted in a CYP2A6 mutant protein (I208S/I300F/G301A/S369G) with binding affinities for MAP and PEITC much more similar to those observed for CYP2A13 than to those for CYP2A6 without altering coumarin binding. The structure-based quantitative structure-activity relationship analysis using COMBINE successfully modeled the observed mutant-ligand trends and emphasized steric roles for active site residues including four substituted amino acids and an adjacent conserved Leu(370).

Breast cancer in the United States: the burden on an aging, changing nation

Abstract #6076

Background: Over the next 20 years, important demographic changes in the US will emerge, with the number of older and non-white Americans increasing dramatically. Though breast cancer incidence is known to vary by both age and race, the projected impact of impending population changes on breast cancer incidence has never been quantified. To delineate the future burden of breast cancer, we calculated population-based projections of breast cancer incidence through 2030.
 Material and Methods: SEER data provided current age- and race-specific incidence rates for invasive or in situ female breast cancer. Age- and race-specific projections for the US population through 2030 were derived from Census Bureau data. Assuming stable race- and age-adjusted incidence, the total number of breast cancer cases by race and age through 2030 was estimated.
 Results: From 2008 to 2030, the total number of breast cancer cases is expected to increase from 264,000 to 357,000. Of cases diagnosed in 2030, 60% will occur in women ages 65 and older. This represents a 67% increase in the number of breast cancer cases in women age 65 and over (from 127,000 to 212,000), compared to a 6% increase in women under age 65 (from 137,000 to 145,000). In 2030, 19% of all cases will occur in non-whites, representing a 70% increase in non-whites (from 40,000 to 68,000), compared to a 29% increase in whites (from 224,000 to 289,000). While cases in older non-white women currently represent only 13% of older patients, they will comprise 17% by 2030.
 Discussion: With major demographic shifts on the horizon, an imminent wave of older breast cancer patients will impose a substantial burden on the US healthcare system. Efforts to expand capacity, contain cost, and define optimal treatment for older patients are urgently needed. Moreover, the projected increase in the percentage of breast cancer in non-whites heightens the importance of efforts to identify and minimize health care disparities.
 


Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6076.

Breast brachytherapy in the United States: how is this emerging modality being incorporated into the care of older breast cancer patients?

Abstract #6087

Introduction: Several studies have demonstrated the potential value of brachytherapy in the treatment of breast cancer, either as local boost irradiation, or alone as accelerated partial breast irradiation, after breast conserving surgery (BCS). In 2002, the Food and Drug Administration approved the first balloon-based brachytherapy delivery system, signaling the beginning of broader incorporation of partial breast irradiation into breast cancer treatment. While subsequent studies have been seeking to define the patient population that will derive optimal clinical benefit from breast brachytherapy, this treatment option has remained widely available for use in a variety of settings. However, no prior study has described the frequency of breast brachytherapy use in the US. In a population-based cohort of older breast cancer patients, we characterized utilization of breast brachytherapy across the nation at the inception of this era.
 Methods: A cross-sectional sample from a national Medicare database identified 37,323 beneficiaries (age≥65) with newly diagnosed invasive breast cancer treated with BCS in 2003. ICD-9 and CPT codes indicated receipt of external beam radiotherapy (EBRT) and brachytherapy. Percent use by state, region, age, and race was compared using Pearson χ2.
 Results: Across the nation, 73% of older patients were treated with any radiotherapy after BCS. Of these patients, 97% were treated with EBRT alone, 3% with brachytherapy alone, and <1% with EBRT plus brachytherapy boost. For patients treated with brachytherapy, 98% received interstitial therapy and 2% intracavitary therapy. Though percent utilization of brachytherapy modalities ranged from 1% to 4% across different locations in the US, no statistically significant variation was detected by state (P=0.62) or by region (P=0.32). In addition, brachytherapy use did not differ by race (P=0.63) or age (P=0.59).
 Conclusions: At the inception of the era in which partial breast irradiation was becoming incorporated into the care of breast cancer patients, only a small percentage of all patients received breast brachytherapy across the US. As contemporary data become available, future studies may seek to trace how this new treatment strategy is becoming more widely integrated into routine breast cancer treatment.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6087.

The sandhopper Talitrus saltator (Crustacea: Amphipoda) as a biomonitor of trace metal bioavailabilities in European coastal waters

The amphipod crustacean Talitrus saltator is an established, easily accessible, biomonitor of trace metal bioavailabilities in coastal waters. We have carried out a geographically widespread collection of T. saltator from European shores, stretching from the north-west Atlantic through the Baltic to the Mediterranean. A primary aim of the work was to establish a database of accumulated trace metal concentrations (Cd, Cr, Cu, Fe, Mn and Zn) in this biomonitor. Statistical analysis has shown significant geographical differences in the bioavailabilities of all the metals, the most distinct being copper, iron and manganese. It has proved possible to identify unusually high accumulated concentrations of Cd, Cr, Cu, Fe, Mn and Zn in this biomonitor, indicative of high metal bioavailability at a particular site. These may serve as reference points for future biomonitoring programmes seeking to identify metal contamination in coastal waters.

Salvage transplantation for allograft failure using fludarabine and alemtuzumab as conditioning regimen

Graft failure after allogeneic blood or marrow transplantation, although generally uncommon, can be a devastating complication. This report includes the outcome of nine patients who received a salvage transplant for failure to engraft after one (n=8) or 2 (n=1) prior transplants. Eight patients received allografts from the original donor. All received fludarabine 30 mg/m(2) i.v. and alemtuzumab 20 mg i.v. daily from days -6 to -2. Daily CYA was begun on day -2, and the allograft was infused on day 0. The therapy was well tolerated with low toxicity, and all nine patients engrafted, recovering neutrophils at a median of 12 days after transplant. Four patients died: two of relapse, one of a fungal infection in the setting of GVHD and one of multiple sclerosis. The combination of fludarabine and alemtuzumab is an effective and well-tolerated salvage conditioning regimen for patients who experience graft failure after blood or marrow transplants.

Immunotherapy for myeloid leukemias: current status and future directions

Myeloid leukemias, although a heterogeneous group of hematopoietic stem cell neoplasms, are arguably among the most suited for active specific immunotherapy. Nevertheless, clinical development of myeloid leukemia vaccine lagged behind similar approaches in other solid and hematological malignancies. The recent identification of apparently specific leukemia antigens and advances in understanding the fundamentals of tumor immunology have helped initiate a number of early phase clinical studies evaluating the safety and clinical efficacy of this approach. Here we review the recently identified and characterized putative leukemia antigens, the main vaccination strategies employed by most investigators and the results of clinical studies of immunotherapy of myeloid leukemias. Although these studies are early and often difficult to interpret, they offer evidence that effective immunity to leukemia could be induced following vaccination, and that clinical benefit can sometimes be observed, thus setting the stage for future development of this strategy and in the combinatorial approaches to treatment of myeloid leukemias that incorporate immunotherapy.

Functional characterization of CYP2A13 polymorphisms

CYP2A13 is an efficient catalyst of metabolic activation of the human carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN). This study investigated the functional consequences of CYP2A13 polymorphisms that result in single amino acid substitutions. Five CYP2A13 variants, namely CYP2A13*2 (R257C), CYP2A13*5 (F453Y), CYP2A13*6 (R494C), CYP2A13*8 (D158E), and CYP2A13*9 (V323L), were expressed and evaluated for coumarin binding affinity, coumarin 7-hydroxylation, and -hydroxylation of (S)-NNN and NNK. In addition, the 133_134 Thr deletion variant, coded for by CYP2A13*3, was expressed but was not stable to the protein purification procedure. A 30-42% decrease in coumarin 7-hydroxylation catalytic efficiency was determined for R257C and D158E. No effect on coumarin binding or (S)-NNN metabolism was observed. Three variants, R257C, D158E, and V323L, had two- to threefold decreased catalytic efficiency for NNK -hydroxylation. CYP2A13 polymorphisms resulted in modest changes in coumarin 7-hydroxylation and NNK -hydroxylation activities in vitro. Although these changes are not likely to impact in vivo metabolism, these data should aid in the interpretation and design of future epidemiology studies.

Joseph Swan (1791-1874): pioneer of research on peripheral nerves

Joseph Swan was born in 1791 and appointed surgeon to Lincoln County Hospital in 1814. In addition to his clinical work, he carried out what were probably the first animal experiments on nerve injuries. These were mostly on rabbits, in which the sciatic nerves were partly or wholly divided, had a section excised, or were ligated. He found that regeneration could occur, even after neurectomy. He reported these results, together with his experience in human patients and the effects of neurectomy in a horse, in an essay of 1819, which won the Jacksonian Prize of the Royal College of Surgeons of England and is still preserved there. In 1827 he moved to London, where he devoted himself mainly to dissections of the nervous system and was active in the College. He retired to Filey in Yorkshire, where he died in 1874.

Butyltins, trace metals and morphological variables in surf scoter (Melanitta perspicillata) wintering on the south coast of British Columbia, Canada

From 1998 to 2001 we examined spatial and temporal variation in uptake of contaminants by surf scoters (Melanitta perspicillata) in the Georgia Basin region of the Pacific coast of Canada. Samples were collected during late fall and early spring at industrialized and reference locations, carcasses examined, and tissues collected for histology, biomarkers, and contaminant analyses. Scoters from both Vancouver and Victoria harbours had significantly higher hepatic concentrations of summation operatorbutyltins than birds from a reference site. In adult male surf scoters, hepatic summation operatorbutyltins increased over the winter at two sites (p=0.02, n=26), while mercury increased (p=0.03, n=15) and selenium decreased at one site (p=0.001, n=15). Body condition decreased over the winter at both the treatment site, Howe Sound (p<0.0001, n=12), and the reference site, Baynes Sound (p=0.02, n=15). Multiple regression analysis using Akaike's Information Criteria (AIC(C)) showed an association between hepatic butyltin concentrations and overall body condition (p=0.06, r=-0.237).

Myelodysplastic Syndromes: Review of Pathophysiology and Current Novel Treatment Approaches

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal disorders of hematopoietic progenitors manifest by cytopenias, bleeding, infection, and potential for progression to acute myelogenous leukemia. The wide spectrum of clinical manifestations, including variability in illness severity and potential for progression, suggest that myelodysplastic syndromes encompass a multitude of disorders, likely involving numerous pathologic pathways. In fact, it is the effort to understand the underlying biology of these syndromes that has led to recent advances in treatment approaches, including the FDA approval of three new agents (5-azacitidine, decitabine, and lenalidomide) for the treatment of MDS. This review will present data supporting each of the current pathophysiologic pathways implicated in the development and progression of MDS; summarize the emerging clinical paradigms for treating patients with MDS; and offer insights into several novel approaches attempting to improve treatment options for future MDS patients.

Acute bilineal leukemia: a rare disease with poor outcome

Most cases of acute leukemia can be assigned to the myeloid, B or T lineage. In a few cases, definitive assignment cannot be achieved because blasts express antigens of more than one lineage. A subset of these, referred to as acute bilineal leukemias (aBLLs), is characterized by the presence of more than one population of blasts, each comprising a single lineage. We identified 19 cases of aBLL, including 10 mixed T and myeloid (T-My) and nine mixed B and myeloid (B-My); no mixed B and T cases were identified. Cytogenetic data were available for 16 patients. Three of seven patients with B-My had a t(9;22)(q34q11.2), two had 11q23 translocations and one had del(9). Two of nine patients with T-My had 2p13 translocations; five had other unrelated abnormalities. Of 16 patients with outcome data, only six achieved complete remission and only two remain free of disease 2.5 and 4.5 years after chemotherapy or stem cell transplantation. aBLL is a rare disease that combines B or T and myeloid blasts. Cytogenetic abnormalities of t(9;22) and 11q23 are common in, and may be restricted to, B-My cases, while T-My cases have frequent but generally non-recurring abnormalities. Both types of aBLL are associated with poor outcome.

Induction of acute lymphocytic leukemia differentiation by maintenance therapy

Despite extensive study in many malignancies, maintenance therapy has clinically benefited only two diseases: acute lymphocytic leukemia (ALL) and acute promyelocytic leukemia (APL). ALL maintenance therapy utilizes low-dose 6-mercaptopurine (6MP) and methotrexate (MTX), while maintenance in APL primarily consists of all-trans-retinoic acid (ATRA). 6MP and MTX as used in ALL are also now usually added to maintenance ATRA for APL, based on data suggesting an improved disease-free survival. Although the mechanism of action of MTX and 6MP as maintenance is unknown, low-dose cytotoxic agents are potent inducers of differentiation in vitro. Thus, we studied whether maintenance therapy in ALL, like ATRA in APL, may be inducing terminal differentiation of ALL progenitors. The APL cell line NB4, the ALL cell lines REH and RS4;11, and patients' ALL blasts were incubated with ATRA, 6MP, and MTX in vitro. All three drugs inhibited the clonogenic growth of the APL and ALL cell lines without inducing immediate apoptosis, but associated with induction of phenotypic differentiation. The three drugs similarly upregulated lymphoid antigen expression, while decreasing CD34 expression, on patients' ALL blasts. These data suggest that induction of leukemia progenitor differentiation plays an important role in the mechanism of action of maintenance therapy in ALL.

Phase II study of induction docetaxel/cisplatin with rhG-CSF followed by concurrent pulsed docetaxel chemoradiation for stage III non-small cell lung cancer (NSCLC)

17034

Background: Both local and distant failures contribute to poor outcome in chemoradiation (CRT) for stage III NSCLC. Our previous study applied pulsed low-dose paclitaxel CRT for stage III NSCLC yielded 97.6% in-field tumor control and a modest survival gain. A follow-up study was designed to target distant micrometastasis up-front by one-cycle induction (IND) chemotherapy (CT) w/o further delay of local therapy. This was followed by low-dose sensitizing docetaxel (Doc) CRT. Methods: IND CT consisted of day 1 Doc 75 mg/m2 & cisplatin 75 mg/m2, and rhG-CSF (150 mg/m2 days 2–10). CRT started 3–6 wks later. Twice-weekly Doc at 12 mg/m2 was given with daily RT of 64.8 Gy to gross dz and 45–57.6 Gy to subclinical dz. Toxicity (Tox), response and survival were assessed. Results: 22 pts enrolled with 16 evaluable. 6 did not complete due to: allergy, intercurrent dz or progressive dz prior-to/during RT. Overall response was 69%. Kaplan-Meier survival was 67%, 55%, and 55% for years 1, 2, and 3. Grade (Gd) 3 Tox of IND CT included: allergy (10%), infection/nl ANC (20%), nausea (10%), HTN (5%) hyperglycemia (5%), H/A (5%), fatigue (10%), dyspnea/gd 4 hyperglycemia/fatigue (5%). No gd 3/4 hematologic Tox. Esophagitis was the main Tox of CRT. Doc was reduced after 10th pt enrolled for high incidence of gd 3 esophagitis: 4/8 (50%) at Doc dose of 12 mg/m2. Subsequent pts received reduced Doc of 10 mg/m2 and 1/8 had gd 3 esophagitis (12.5%). Other gd 3 Tox of CRT included: fatigue (14%), appetite loss (14%), flushing (7%), chest pain (7%), diarrhea (7%), and nausea (28%). No other gd 3 or 4 Tox from CRT. Conclusion: The regimen is associated with low hematologic Tox. Despite published MTD of twice-weekly Doc/RT at 15 mg/m2, 50% treated at 12 mg/m2 had gd 3 esophagitis. This was reduced to 12.5% at 10 mg/m2. Local response was 69% and survival was much better compared with our previous study of pulsed paclitaxel/RT w/o IND CT, which yielded 2 and 3-year survival of 33% and 18% for all, and 40% and 21% for pts completed protocol (Chen et al Clin Cancer Res 9:969–975,2003). Data suggest that one-cycle IND CT followed by low-dose taxane-based CRT improves survival of stage III NSCLC pts and deserves further investigation. Study partly supported by Sanofi-Aventis.

No significant financial relationships to disclose.

Quantitative analysis of bone marrow CD34 cells in aplastic anemia and hypoplastic myelodysplastic syndromes

Aplastic anemia (AA) and hypoplastic myelodysplastic syndromes (hMDS) are often difficult to distinguish. However, an accurate diagnosis is important because the prognosis and treatment of these diseases may differ. CD34+ hematopoietic progenitors are central to the pathogenesis of both disorders; they are the targets of the autoimmune attack in AA and neoplastic transformation in MDS. The aim of this study was to assess whether bone marrow CD34+ cell numbers could be used in differentiating between AA and hMDS. The percentage of bone marrow CD34+ cells was normal or increased (mean -3.5+0.5%, range 1-7%) in 15 of 35 patients studied, and low (mean -0.13 +/- 0.02%, range 0.02-0.36%) in 20 of 35 patients. All patients with a normal or increased percentage of CD34+ cells were ultimately diagnosed with hMDS based on the detection of clonal cytogenetic abnormalities or progression to refractory anemia with excess blasts/acute myeloid leukemia. All patients with low marrow CD34+ cell numbers met standard clinical criteria for AA and have not demonstrated neoplastic transformation with follow-up. Quantification of marrow CD34+ cells may serve as an important tool for distinguishing between AA and hMDS.

Factors influencing the discomfort of intraoral needle penetration

This study with 24 volunteers compared the discomfort produced by needle penetration in different parts of the palatal mucosa. In addition, comparing a fresh needle to one that was used for a previous penetration in the same patient, we assessed the influence of the status of the needle on insertion discomfort during buccal mucosal penetration. The results showed that needle penetration in the anterior hard palate was more uncomfortable than in the posterior palate. Although men could not differentiate between fresh and used needles for a second buccal mucosal penetration, women reported a significant increase in discomfort with used needles.

New concepts in the treatment of acute myeloid malignancies: selected pathways for targeted therapy

Acute myeloid leukemia (AML) and myelodysplasia (MDS) continue to present formidable treatment challenges as there is not yet a "standard approach" that reliably and safely cures the majority of adults with these disorders. Understanding the basic cellular and molecular biology of leukemia is vital to the development of better treatment approaches. All malignant cells, including leukemias, carry survival advantages compared to their normal counterparts. These survival advantages are particularly evident when the cells face both normal environmental stressors as well as extreme stressors of potentially lethal DNA damage. The impact of such stressors is ultimately determined by the signaling pathways and resultant cellular activation, including alterations in cellular growth, differentiation, survival and death. It is our improving understanding of these signaling pathways, both normal and malignant, that provide the targets for novel therapies. In this review article, we will focus on several signaling pathways, as well as the regulation of the cell cycle, that not only represent potentially accessible sites for intervention in myeloid malignancies, but those that are actively being studied.

Accumulation and soluble binding of cadmium, copper, and zinc in the polychaete Hediste diversicolor from coastal sites with different trace metal bioavailabilities

Bioaccumulation of cadmium, copper, and zinc was examined in common ragworms Hediste diversicolor from control (Bay of Somme, Blackwater) and metal-rich (Seine estuary, Boulogne harbor, Restronguet Creek) sites in France and the United Kingdom. The degree of exposure in the field was assessed by considering both total concentrations in superficial sediment and the quantities of metals which may be released in vitro at different pH levels. Among the three contaminated sites, release of the three metals was not detectable in Boulogne harbor, in correlation with limited enhancement of the metal concentrations in the common ragworms from this site. Even at those sites where zinc could be released in vitro from the sediment, zinc concentrations were not enhanced in common ragworms, in agreement with previous findings indicating that the body content of this metal is regulated in H. diversicolor. At all the studied sites, bioaccumulated zinc was mainly in cytosolic form. The distribution of cadmium and copper varied according to the origin of the common rag-worms, the insoluble fraction increasing with the degree of contamination (cadmium in the Restronguet Creek, copper in the Seine estuary, and even more in Restronguet Creek). In the cytosolic fraction, metals were partly linked to cytosolic heat-stable thiolic compounds (CHSTC) with molecular masses (5-6 kDa and about 12 kDa) consistent with metallothionein-like proteins (MTLP). Metal-binding to MTLP varied with the degree of contamination and with the metal studied. In contrast to many invertebrates, the presence of metal-binding CHSTC (MM about 2 kDa) other than MTLP seems to be a peculiar feature of H. diversicolor.

Inhibition of the transforming activity of FLT3 internal tandem duplication mutants from AML patients by a tyrosine kinase inhibitor

FLT3 is a receptor tyrosine kinase that may play a role in a significant proportion of leukemias. In addition to being aberrantly expressed in acute leukemias, activating mutations of the FLT3 gene have been found in patients with AML, myelodysplastic syndrome (MDS) and more rarely, ALL. Internal tandem duplications (ITDs) of the FLT3 gene have been detected in 17-34% of patients with AML and portend a poor prognosis for these patients. FLT3 receptors containing ITD mutations (FLT3/ITDs) are constitutively activated in the absence of FLT3 ligand (FL) stimulation leading to the activation of downstream signaling proteins, including ERK and STAT 5. FLT3 activity, therefore, is a logical target for therapeutic intervention. AG1296 is a tyrosine kinase inhibitor of the tyrphostin class that shows inhibitory activity for wild-type FLT3, in addition to the PDGF and c-KIT receptors. We examined the inhibitory effects of AG1296 on FLT3/ITDs isolated from AML patients in the IL-3-dependent cell line, Ba/F3, as well as in primary leukemia samples from AML patients. Immunoprecipitation and immunoblotting analyses demonstrated that FLT3/ITDs were constitutively phosphorylated in the absence of FL. The auto-phosphorylation of FLT3/ITDs was inhibited by AG1296 with an IC(50) of approximately 1 microM. FLT3/ITDs were associated with constitutive phosphorylation of ERK, STAT 5A, STAT 5B, CBL, VAV and SHP2 in Ba/F3 cells. The phosphorylation of these downstream signaling molecules was suppressed in a dose-responsive fashion by AG1296. AG1296 inhibited IL-3 independent growth and induced apoptosis in Ba/F3 cells transformed by FLT3/ITDs. AG1296 also inhibited FLT3 auto-phosphorylation, and induced a cytotoxic effect, in primary AML cells. These findings suggest that inhibiting the activity of FLT3 may have a therapeutic value in some leukemias expressing FLT3/ITDs.

Partitioning of accumulated trace metals in the talitrid amphipod crustacean Orchestia gammarellus: a cautionary tale on the use of metallothionein-like proteins as biomarkers

The induction of metallothionein-like proteins (MTLP) as biomarkers of trace metal pollution has been investigated in the talitrid amphipod Orchestia gammarellus, an established biomonitor of trace metal availabilities in coastal areas. Sensitivity to metal exposure, MTLP and copper and zinc concentrations have been examined in amphipods from a metal-contaminated site (Dulas Bay, Wales) and two clean sites (Millport, Scotland and Bradwell, England). Groups of 10 amphipods from Dulas Bay and Millport were exposed separately to one of a concentration series (1, 3.16, 10, 31.6, 100 microM) of Cu or Zn for 17 days at 10 degrees C. Specimens from Bradwell were exposed under similar conditions but the experiment was extended to 25 days with intermediate samplings at 5, 10 and 17 days and additional groups were exposed to a mixture of Cu+Zn (7:10 molar ratio). In addition, specimens from Millport were exposed to 1 or 31.6 microM Cd for 17 days. Amphipods from Dulas Bay, which had been chronically exposed to metals in their natural environment had not acquired any tolerance to Cu and Zn since the lowest LC 50s were registered in these samples. Whatever the origin of the amphipods experimentally exposed to metals and whatever the dose of exposure, both Cu and Zn remained approximately equally distributed between cytosolic and insoluble fractions in the amphipods, suggesting that mechanisms of metal storage were identical over the whole range of conditions. Concentrations of MTLP were higher in O. gammarellus from Dulas Bay than in those from Millport analysed directly after collection, although laboratory exposures to dissolved Cd, Cu or Zn have failed to demonstrate differences in the induction of MTLP between amphipods from the clean or contaminated sites. A potential role for metallothionein-like proteins as biomarkers is thus unlikely although it remains plausible that turnover of these proteins does increase in response to increased metal challenges, enabling MTLP to play a role in metal detoxification.

Trace metal uptake by the Chinese mitten crab Eriocheir sinensis: the role of osmoregulation

Changes in salinity affect the bioavailability and consequent uptake of trace metals by euryhaline invertebrates. In many cases, salinity-related effects on metal uptake can be explained by changes in chemical speciation but salinity may also influence uptake indirectly through its action on osmoregulatory mechanisms. Specifically, it can be hypothesised that trace metal uptake may be reduced at salinities approaching the isosmotic point of a species because, at this point, there is reduced activity of ionic exchange pumps. The present study tested this hypothesis using the Chinese mitten crab, Eriocheir sinensis, a hyper-hypoosmoregulator with an isosmotic point around 33 per thousand. Crabs were exposed to radio-labelled cadmium and zinc at 23, 33 and 43 per thousand for 4 days. To eradicate speciation effects, crabs were exposed to the same concentration of the radio-labelled free metal ion (estimated using MineQL computer software) at each salinity. Haemolymph samples were taken daily and radio-labelled metal concentrations were estimated from radioactivity counts and used to provide relative measures of metal uptake. Neither cadmium nor zinc uptake was lowest at the isosmotic point. The uptake of cadmium increased significantly with increase in salinity, while the uptake of zinc showed no significant change with increased salinity. Thus changes in trace metal uptake rates in E. sinensis do not appear to be controlled only by changes in free metal ion concentrations. The different effects of salinity change on the uptake of cadmium and zinc (in the absence of free metal ion change) also indicate that physiological responses to osmotic change alone do not control metal uptake rates for this species.