Biomonitoring of trace metal contamination in the Potengi estuary, Natal (Brazil), using the oyster Crassostrea rhizophorae, a local food source

The oyster Crassostrea rhizophorae was collected in September 1997 from 10 stations along the Potengi estuary, Natal, Brazil, a mangrove-lined estuary receiving anthropogenic inputs of trace metals. C. rhizophorae is a net accumulator of trace metals and can be used as a biomonitor, the accumulated soft tissue concentrations representing integrated records of bioavailable metal fractions over the life of the oyster. Significant differences in oyster accumulated concentrations (and hence bioavailabilities) of Fe, Zn, Cu, Cr, Pb, Cd, Ni and Ag (but not Mn) were found between stations, and attributed to anthropogenic inputs including discharges of sewage and industrial effluent. The oysters are also a local food source, and concentrations of zinc, copper and lead in some of the oysters are above typical public health recommended limits.

A member of the Y-box protein family interacts with an upstream element in the alpha1(I) collagen gene

Transforming growth factor beta (TGF-beta) stimulates protein complex formation on a TGF-beta response element (TAE) found in the distal portion (-1624) of the collagen alpha 1(I) promoter. To identify the fibroblast proteins in this complex, an expression library constructed from human embryonic lung fibroblasts mRNA was screened using a tetramer of TAE. Y-box binding protein (YB-1), was identified as a protein in the TAE-protein complex. The protein expressed by phage clones formed a specific complex with labeled TAE but not mutated TAE (mTAE) similar to the complex formed with nuclear protein. Nuclear protein-TAE complexes isolated from native gels contained YB-1 by Western analysis. TGF-beta treatment increased the amount of YB-1 protein in nuclear extracts, decreased its amount in cytoplasm, but did not alter the steady state levels of YB-1 mRNA. A full-length YB-1 protein expressed in human lung fibroblasts was primarily located in the nucleus with punctate staining in cytoplasmic regions. The expression of YB-1 decreased in the cytoplasm after 2 h of TGF-beta treatment. Therefore, the increased binding activity seen in TGF-beta-stimulated nuclear extracts was due primarily to relocalization of YB-1 from the cytoplasm to the nuclear compartment. Co-transfection of YB-1 cDNA with a collagen promoter-reporter construct caused a dose-dependent activation of collagen promoter activity in rat fibroblasts whereas the promoter with a mutation in the TAE element was not sensitive to YB-1 co-expression. In conclusion, we have identified YB-1 as a protein that interacts with a TGF-beta response element in the distal region of the collagen alpha 1(I) gene. YB-1 protein activates the collagen promoter and translocates into the nucleus during TGF-beta addition to fibroblasts, suggesting a role for this protein in TGF-beta signaling.

Using pentafluorophenyl as a Lewis acid to stabilize a cis secondary amide conformation

[reaction: see text]. N-(pyrimidin-2-yl)pentafluorobenzamide adopts a cis amide bond in the solid state with a pyrimidyl nitrogen pointing toward the center of the perfluorophenyl ring. In solution, the compound is a mixture of cis and trans rotamers. The conformational equilibrium is strongly solvent dependent, and the cis rotamer is entropically favored. It is proposed that the entropic driving force is decreased solvation of the two aryl groups when in the cis conformation.

Durable treatment-free remission after high-dose cyclophosphamide therapy for previously untreated severe aplastic anemia

BACKGROUND

Severe aplastic anemia is a life-threatening bone marrow failure disorder. High-dose cyclophosphamide therapy followed by allogeneic bone marrow transplantation cures the disease. However, it requires a suitable donor and carries the risk for graft-versus-host disease. A small pilot study demonstrated that high-dose cyclophosphamide therapy without bone marrow transplantation leads to durable, treatment-free complete remission.

OBJECTIVE

To confirm the safety and efficacy of high-dose cyclophosphamide therapy alone in patients with severe aplastic anemia.

DESIGN

Uncontrolled clinical trial.

SETTING

Three tertiary care hospitals.

PATIENTS

19 patients with untreated severe aplastic anemia.

INTERVENTION

Cyclophosphamide, 50 mg/kg of body weight per day for 4 consecutive days.

MEASUREMENTS

Probability of response and overall survival were measured. Complete remission was defined as normal blood count for age and sex. Partial remission was defined as independence from transfusion and an absolute neutrophil count greater than 0.5 x 10(9) cells/L without growth factor support. Nonresponders were patients who remained transfusion dependent or died. Relapse was defined as no longer meeting criteria for partial or complete remission.

RESULTS

The median time to an absolute neutrophil count of 0.5 x 10(9) cells/L was 49 days. The probability of survival was 84% (95% CI, 59% to 95%) at 24 months. The probability of achieving treatment-free remission was 73% (CI, 51% to 91%) at 24 months, and the probability of achieving complete remission was 65% (CI, 39% to 89%) at 50 months. No responding patients have had relapse or have developed secondary clonal disorders.

CONCLUSIONS

High-dose cyclophosphamide therapy without bone marrow transplantation produces durable treatment-free remission in severe aplastic anemia. This approach deserves further study in patients with severe aplastic anemia who are not suitable candidates for allogeneic bone marrow transplantation.

A FLT3 tyrosine kinase inhibitor is selectively cytotoxic to acute myeloid leukemia blasts harboring FLT3 internal tandem duplication mutations

Internal tandem duplication (ITD) mutations of the receptor tyrosine kinase FLT3 have been found in 20% to 30% of patients with acute myeloid leukemia (AML). These mutations constitutively activate the receptor and appear to be associated with a poor prognosis. Recent evidence that this constitutive activation is leukemogenic renders this receptor a potential target for specific therapy. In this study, dose-response cytotoxic assays were performed with AG1295, a tyrosine kinase inhibitor active against FLT3, on primary blasts from patients with AML. For each patient sample, the degree of cytotoxicity induced by AG1295 was compared to the response to cytosine arabinoside (Ara C) and correlated with the presence or absence of a FLT3/ITD mutation. AG1295 was specifically cytotoxic to AML blasts harboring FLT3/ITD mutations. The results suggest that these mutations contribute to the leukemic process and that the FLT3 receptor represents a therapeutic target in AML. (Blood. 2001;98:885-887)

Facilitated phosphatidylcholine flip-flop across erythrocyte membranes using low molecular weight synthetic translocases

The transmembrane distribution of phospholipids plays an important regulatory role in human erythrocytes. Membrane-bound translocase enzymes maintain an asymmetric phospholipid distribution across the membrane monolayers by promoting transmembrane diffusion or flip-flop. Mechanistic understanding of the flip-flop process is weak at the molecular level. Recently, we discovered that amide and sulfonamide derivatives of tris(aminoethyl)amine facilitate phospholipid flip-flop across vesicle membranes; that is, they act as low molecular weight, synthetic translocases. In this report, NMR evidence is provided that suggests that the synthetic translocases work by forming a hydrogen-bonded complex with the phosphocholine headgroup which decreases headgroup polarity and promotes diffusion across the lipophilic interior of the membrane. Also cell morphology and fluorescence probe methods are used to show that these synthetic translocases facilitate phosphatidylcholine flip-flop across erythrocyte membranes. Addition of a small amount of dilauroylphosphatidylcholine to erythrocytes produces echinocyte morphology which takes days to revert back to the original discocyte shape. The rate of return is significantly accelerated by the presence of the synthetic translocases. The synthetic translocases facilitate inward-translocation (flip) of the fluorescent phosphatidylcholine probe, 1-palmitoyl-2-(N-[7-nitrobenz-2-oxa-1,3-diazol-4-yl]aminohexanoyl)-sn-glycero-3-phosphocholine (PC-NBD).

Molecular marker expression in oral and oropharyngeal squamous cell carcinoma

OBJECTIVE

To determine the relative prognostic value of p53, cyclin D1, epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) expression in patients with oral and oropharyngeal squamous cell carcinoma.

DESIGN

Retrospective cohort study.

PATIENTS

Fifty-six patients with oral and oropharyngeal squamous cell carcinoma referred to the Department of Therapeutic Radiology at Yale-New Haven Hospital (Conn) between 1981 and 1992 who were treated with gross total surgical resection and postoperative external beam radiotherapy.

RESULTS

Archival tumor tissue was stained with monoclonal antibodies directed against these 4 oncoproteins and scored for staining intensity and percent distribution by a pathologist blinded to the patients' clinical outcomes. Frequency of marker expression was 48% for p53, 20% for cyclin D1, 64% for EGFR, and 41% for VEGF. In multivariate analysis, EGFR positivity was protective against locoregional relapse (relative risk [RR], 0.27; 95% confidence interval [CI], 0.11-0.66; P =.002). In contrast, advanced N stage predicted poor locoregional relapse-free survival (RR, 1.94; 95% CI, 1.03-3.66; P =.04). Predictors of poor overall survival in multivariate analysis included VEGF positivity (RR, 3.53; 95% CI, 1.75-7.13; P<.001) and black race (RR, 2.48; 95% CI, 1.05-5.85; P =.04). Cyclin D1 and p53 expression were not significantly associated with prognosis in this cohort.

CONCLUSIONS

In oral and oropharyngeal squamous cell carcinoma treated with surgery and postoperative radiotherapy, VEGF and EGFR expression may influence clinical outcome. If confirmed, these results have potential implications for the determination of patient prognosis and the development of biologically based pharmacotherapies.

Hemispheric specialization in emotion: attention, arousal, and EEG activation in unilateral temporal lobe epilepsy

To investigate the neural processing of emotion in right and left temporal lobe epilepsy (TLE), we monitored EEG during neutral and emotionally positive and negative auditory stimulation. Left TLE patients displayed increased right lateralization and a negative emotional stimulus rating bias, while right TLE patients did not. This EEG arousal and negative affect may reflect deactivated inhibition of the right hemisphere, symptomatically expressed as arousal and anxiety. Failure to increase lateralization to emotional stimuli in right TLE may reflect compromised emotional attention/arousal centers in the right hemisphere. Results support a two-dimensional theory of the neural processing of emotion.

Boronic acid fluorophore/beta-cyclodextrin complex sensors for selective sugar recognition in water

A novel boronic acid fluorophore 1/beta-cyclodextrin (beta-CyD) complex sensor for sugar recognition in water has been designed. The probe 1 bearing pyrene moiety as a fluorescent signal transducer exhibits no fluorescence emission, due to its aggregation in water containing 2% DMSO; however, the addition of beta-CyD to this solution largely changes UV-vis and fluorescence spectra of 1 by forming an inclusion complex with beta-CyD, and an efficient fluorescence emission response of 1/beta-CyD complex upon sugar binding is found to be obtained at pH 7.5. The pH-fluorescence profile of the 1/beta-CyD complex reveals that the boronate ester formation with fructose induces the apparent pKa shift from 7.95+/-0.03 in the absence of fructose to 6.06+/-0.03 in the presence of 30 mM fructose, resulting in the fluorescence emission response under the neutral condition. The spectral properties of 1 in 95% methanol:5% water (v/v), as well as the fluorescence quenching study of 1-methylpyrene with 4-methoxycarbonylphenyl-boronic acid 2, demonstrate that the response mechanism is based on the photoinduced electron transfer (PET) from the pyrene donor to the acid form of phenylboronic acid acceptor in 1, and thus, the proton dissociation of phenylboronic acid induced by sugar binding inhibits the PET system while increasing the fluorescence intensity of the pyrene moiety. To evaluate the binding ability and selectivity of the 1/beta-CyD complex for monosaccharides in water, the response equilibria have been derived. The 1:1 binding constants of the 1/beta-CyD complex obtained from the equilibrium analysis are in the order: D-fructose (2515+/-134 M(-1)) >> L-arabinose (269 +/- 28 M(-1)) > D-galactose (197+/-28 M(-1)) > D-glucose (79+/-33 M(-1)), which is consistent with the binding selectivity of phenylboronic acid.

Biology and management of idiopathic myelofibrosis

Idiopathic myelofibrosis (IMF) is a hematopoietic stem cell disorder characterized by hypercellularity of the bone marrow with an increase in abnormal megakaryocytes, varying degrees of marrow fibrosis, and extramedullary hematopoiesis. The central lesion of the IMF stem cell is not known; however, the marrow fibrosis is a polyclonal reaction to inflammatory mediators generated by the transformed clone. Historical management approaches have centered on improving the patient's blood counts in a palliative manner. Recent reports of autologous and allogeneic bone marrow transplantation (BMT) in IMF patients indicate that stable engraftment occurs easily, the marrow fibrosis is a reversible process, and a graft-versus-fibrosis effect may exist. The goals of future therapies will target marrow fibrosis and harness the graft-versus-fibrosis effect to safely and effectively treat patients with IMF.

Molecular markers in head and neck squamous cell carcinoma: their biological function and prognostic significance

Head and neck squamous cell carcinoma affects more than 500,000 people worldwide each year. Despite optimal treatment with surgery, irradiation, and chemotherapy, disease recurrence and progression remains a common and challenging oncological problem. Recently, interest has developed in identifying novel molecular markers that allow identification of those patients at increased risk for locoregional recurrence and death. This article reviews several such molecular markers studied in head and neck cancer, including p53, angiogenesis-related markers, cyclin D1, and epidermal growth factor receptor. The biological function of these markers and the potential clinical implications are discussed. The purpose of this review is to update the otolaryngologist on a rapidly emerging segment of applied translational research in our field.

E-cadherin expression is silenced by 5' CpG island methylation in acute leukemia

E-Cadherin is a transmembrane glycoprotein that mediates Ca2+-dependent intercellular adhesion in normal epithelium. In tumors of epithelial origin, E-cadherin expression frequently is reduced, an event that contributes to tumor invasion and metastasis. The role of E-cadherin in hematopoietic tissues is less clear. In normal bone marrow, E-cadherin is expressed on erythroid progenitors, CD34+ stem cells, and stromal cells, where it likely contributes to intercellular interactions during hematopoiesis. In this study, we used a nested-PCR approach to examine the methylation status of the E-cadherin 5' CpG island in blood and bone marrow samples from normal donors and in bone marrow from patients with acute leukemia. In normal peripheral blood mononuclear cells and bone marrow, E-cadherin was completely unmethylated. In peripheral blood mononuclear cells, expression was evident by reverse transcription-PCR. Immunoblotting confirmed E-cadherin protein expression in two lymphoblastoid cell lines derived from normal donors. In contrast, E-cadherin was aberrantly methylated in 4 of 4 (100%) leukemia cell lines, 14 of 44 (32%) acute myelogenous leukemias, and 18 of 33 (53%) acute lymphoblastic leukemias. Genomic bisulfite sequencing of primary leukemias confirmed dense methylation across the CpG island. Methylation was associated with loss of E-cadherin RNA and protein in leukemia cell lines and primary leukemias. Following treatment with 5-aza-2'-deoxycytidine, a methylated leukemia cell line expressed both E-cadherin transcript and protein. Our results show that methylation of E-cadherin occurs commonly in acute leukemia and suggests a hypothesis for E-cadherin down-regulation in leukemogenesis.

Universal newborn hearing screening

BACKGROUND

New technology has made universal newborn hearing screening possible. Our goal was to investigate the feasibility of universal newborn screening using distortion product otoacoustic emissions (DPOAE) on infants in a community hospital in a normal newborn nursery.

METHODS

We used DPOAE to screen newborn infants from February 1997 to March 1999.

RESULTS

Of 1002 infants, 111 failed the initial screen (11.1%). When screening was repeated, only 2 infants failed. One infant failed the second screen and a tympanogram. He was treated and he passed a third use of DPOAE. An additional infant failed the repeat screen but passed the tympanogram. That infant was referred on for auditory brain response testing.

CONCLUSIONS

DPOAE testing can be accomplished easily in a normal newborn nursery with an acceptable false-positive rate when a two-stage approach is used. The cost for each test was $19.88. The cost to find the 1 infant with sensory neural hearing loss was $22,114.

High-generation polycationic dendrimers are unusually effective at disrupting anionic vesicles: membrane bending model

The membrane disruption properties of high generation (G4 to G7) poly(amidoamine) (PAMAM) dendrimers are evaluated and compared to linear poly(lysine). The G6 and G7 dendrimers are unusually effective at inducing leaky fusion of anionic, large unilamellar vesicles, as determined by standard fluorescence assays for lipid mixing, leakage, and contents mixing. Both G7 dendrimer and poly(lysine) are able to disrupt sterically stabilized vesicles that are coated with poly(ethylene glycol). A G7 dendrimer/DNA complex with a 1:1 concentration ratio of dendrimer surface amines to DNA phosphate groups is unable to induce leakage of 3:7 POPA-PE vesicles; however, extensive leakage is observed when the surface amine to phosphate stoichiometry is >/=3:1. Thus, the DNA/dendrimer complexes that typically induce high levels of cell transfection are also able to induce high levels of vesicle leakage. The G7 dendrimer does not induce membrane phase separation in 3:7 POPA-PE vesicles, but an inverse hexagonal phase is observed by (31)P NMR. The enhanced membrane disruption is interpreted in terms of a membrane bending model. A rigid, polycationic dendrimer sphere uses electrostatic forces to bend a malleable, anionic membrane and induce bilayer packing stresses. This bending model is biomimetic in the sense that protein-induced membrane bending is currently thought to be an important factor in the fusion mechanism of influenza virus.

BP1, a new homeobox gene, is frequently expressed in acute leukemias

Aberrant expression of homeobox genes has been described in primary leukemia blasts. We recently cloned a new cDNA, BP1, which is a member of the homeobox gene family. BP1 expression was investigated in bone marrow samples from acute myeloid leukemia (AML), acute T cell lymphocytic leukemia (ALL) and pre-B cell ALL. Expression levels of two apparent isoforms of BP1, DLX7 and DLX4, were measured in the same samples. They are weakly if at all detectable in normal bone marrow, PHA-stimulated T cells or B cells. BP1 RNA was highly expressed in 63% of AML cases, including 81% of the pediatric and 47% of the adult cases, and in 32% of T-ALL cases, but was not found in any of the pre-B ALL cases. Coexpression of BP1, DLX7 and DLX4 occurred in a significant number of leukemias. Our data, including co-expression of BP1 with c-myb and GATA-1, markers of early progenitors, suggest that BP1 expression occurs in primitive cells in AML. Analysis of CD34+ and CD34- normal bone marrow cells revealed BP1 is expressed in CD34- cells and virtually extinguished in CD34+ cells. Ectopic expression of BP1 in the leukemia cell line K562 increased clonogenicity, consistent with a role for BP1 in leukemogenesis. The presence of BP1 RNA in leukemic blasts may therefore be a molecular marker for primitive cells and/or may indicate that BP1 is an important upstream factor in an oncogenic pathway.

Trait anxiety and prior exposure to non-stressful stimuli: effects on psychophysiological arousal and anxiety

Arousal and anxiety responses to stressful stimulation are products of multiple factors that may include the physiological, behavioral, cognitive, affective, trait, and state components of our six-system model, as well as mediational and non-mediational perspectives. Within the context of this model, the present experiment examined the effects of prior exposure to neutral stimuli on arousal and anxiety responses to stress. High and low trait-anxious participants were randomly assigned to one of three prior exposure conditions in which they were exposed to stressful stimuli following exposure to: (a) neutral, non-stressful stimulation in the same modality (the Intramodality Prior Exposure or IPE experimental condition); (b) neutral stimuli in a different modality (the Cross-modality Prior Exposure or CPE control condition); or (c) a rest period (the Stress Only or SO control condition). Results showed that low trait anxious subjects had consistently larger arousal and anxiety responses to stress than did highs and that prior exposure to certain same-modality neutral stimuli reduced responses to subsequent stressors. In addition, arousal was greater in response to cognitive than to affective and in response to non-mediational than mediational conditions. Results are discussed in terms of the inverted-U arousal function and of the six-system model and its implications for understanding anxiety and arousal.

Observations on the interaction of zinc and cadmium uptake rates in crustaceans (amphipods and crabs) from coastal sites in UK and France differentially enriched with trace metals

This paper presents results on the possible interaction of zinc and cadmium uptake rates in crustaceans. Zn and Cd uptake rates were measured in amphipods (Orchestia gammarellus) and crabs (Carcinus maenas and Pachygrapsus marmoratus) from five coastal sites in Britain and France subjected to different degrees of trace metal enrichment. The presence or absence of 100 µg l(-1) of one metal (1.53 µM l(-1) Zn, 0.89 µM l(-1) Cd) had an inconsistent effect on the rate of uptake of the other metal by O. gammarellus. The presence or absence of 50 µg l(-1) of either zinc (0.76 µM l(-1)) or cadmium (0.45 µM l(-1)) had no effect on the rate of uptake of the other metal by C. maenas (from Millport, Scotland). Zinc and cadmium uptake rates were correlated in individual amphipods and crabs of both species from the five sites. These correlations indicate that zinc and cadmium might share common routes of uptake from solution by crustaceans, but the metals do not consistently interact competitively or synergistically at the exposure concentrations investigated. Regression coefficients of the relationship between zinc and cadmium uptake rates in amphipods and crabs showed occasional, but inconsistent, differences between sites and over time. All three crustaceans take up zinc from solution at a higher rate than cadmium for the same total dissolved metal molar concentration, but at a lower rate than cadmium per free metal ion molar concentration.

Activase region on chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase. Nonconservative substitution in the large subunit alters species specificity of protein interaction

In the active form of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC ), a carbamate at lysine 201 binds Mg(2+), which then interacts with the carboxylation transition state. Rubisco activase facilitates this spontaneous carbamylation/metal-binding process by removing phosphorylated inhibitors from the Rubisco active site. Activase from Solanaceae plants (e.g. tobacco) fails to activate Rubisco from non-Solanaceae plants (e.g. spinach and Chlamydomonas reinhardtii), and non-Solanaceae activase fails to activate Solanaceae Rubisco. Directed mutagenesis and chloroplast transformation previously showed that a proline 89 to arginine substitution on the surface of the large subunit of Chlamydomonas Rubisco switched its specificity from non-Solanaceae to Solanaceae activase activation. To define the size and function of this putative activase binding region, substitutions were created at positions flanking residue 89. As in the past, these substitutions changed the identities of Chlamydomonas residues to those of tobacco. Whereas an aspartate 86 to arginine substitution had little effect, aspartate 94 to lysine Rubisco was only partially activated by spinach activase but now fully activated by tobacco activase. In an attempt to eliminate the activase/Rubisco interaction, proline 89 was changed to alanine, which is not present in either non-Solanaceae or Solanaceae Rubisco. This substitution also caused reversal of activase specificity, indicating that amino acid identity alone does not determine the specificity of the interaction.

Increasing access and providing social services to improve drug abuse treatment for women with children

AIMS

To assess the impact of a substance abuse treatment program for women with children designed to increase access to treatment through transportation, outreach and child-care services. Also, to assess the impact of using access services on the use of other services and on treatment effectiveness.

DESIGN

A quasi-experimental non-equivalent control group design was used with path analysis to examine the impact of participation in an enhanced services program that provided transportation, outreach and child-care services on the use of other social services and on the use of alcohol and illicit drugs.

SETTING

Treatment clients were interviewed in-person at enhanced treatment programs and regular substance abuse programs.

PARTICIPANTS

Study participants included a randomly selected sample of women with children who were clients of the Illinois Department of Children and Family Services. Participants were enrolled in enhanced or regular substance abuse treatment programs.

MEASUREMENTS

Study participants completed in-person interviews about their characteristics, services use and past and current substance use.

FINDINGS

Participation in the enhanced program was negatively related to substance use. Further, use of access services was related to use of social services which in turn, was negatively related to substance use.

CONCLUSION

The study indicates that services that enhance access to treatment and respond to the range of social service needs of women are important for effective substance abuse treatment for women with children.

Heuristic comparison of sertraline with nortriptyline for the treatment of depression in frail elderly patients

Studies have demonstrated that the selective serotonin reuptake inhibitor antidepressants have similar efficacy to other agents, such as tricyclic antidepressants. However, data are limited for direct comparisons with other antidepressants. The authors conducted a contemporaneous comparison of nursing home residents treated with open-label sertraline in doses up to 100 mg/day with nursing home residents treated in a double-blind randomized study of low vs. regular doses of nortriptyline. There were 97 patients enrolled in the study (28 treated with sertraline), with an average treatment duration of 55 days. There were no differences in the tolerability of sertraline vs. nortriptyline. However, in this group of frail older adults, sertraline was not as effective as nortriptyline for the treatment of depression.