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Objective: The current research examined whether eating disorder risk and the attitudinal elements related to body image predict compulsive buying. Method: A sample of students attending two public universities located in the northeast United States were surveyed. Results: A multiple regression indicated that attitudes related to one's physical appearance, fitness, and health as well as eating disorder risk were predictors of compulsive buying with appearance orientation being the strongest predictor of compulsive buying. Conclusions: Understanding the factors that affect compulsive buying aids the identification of problematic compulsive buying and informs the treatment of compulsive buying. Treatment models may be more effective if additional attention is given to addressing the anxiety compulsive buyers experience when they experience a discrepancy between their ideal and actual self.

Objective: Population-based data on mortality and associated factors in patients with multiple myeloma (MM) are limited. We examined the association between all-cause mortality and demographic and clinical characteristics in newly diagnosed MM patients treated with guideline-recommended chemotherapeutic agents., Research Design and Methods: This retrospective cohort analysis used Medicare 20% data to create a cohort of adult (aged ≥18 years) newly diagnosed MM patients who received chemotherapy 2008-2011 and had no MM diagnosis in the 12 months before the disease index date. Patients were followed from treatment initiation through the earliest of death, loss of insurance coverage, or study end (December 2011). Modified Charlson Comorbidity Index scores and MM-related comorbid conditions (anemia, hypercalcemia, skeletal-related events) were identified in the 6 month pre-index-date period. All-cause mortality and associated factors were examined using multivariable Cox proportional hazard models., Results: We identified 2419 newly diagnosed patients who received MM therapy during follow-up. Mean (SD) and median follow-up were 1.51 (1.0) and 1.37 years. Of the cohort, 55% were female, 78% white, and 92% aged ≥65 years. Pre-index, 54%, 9%, and 5% were diagnosed with anemia, hypercalcemia, and skeletal-related events. Overall, 942 (39%) patients died during follow-up. Factors associated with increased risk of death were older age (≥65 vs. 18-64 years; hazard ratio 1.49, 95% confidence interval 1.13-1.99), higher comorbidity score (≥4 vs. 0; 1.78, 1.43-2.21), anemia (1.23, 1.06-1.42), and hypercalcemia (1.45, 1.19-1.76); female sex (0.86, 0.75-0.98) was associated with decreased risk., Conclusions: Older age, male sex, high comorbidity burden, anemia, and hypercalcemia were risk factors for death in newly diagnosed Medicare MM patients. Study limitations included non-causal observational design, non-validated MM algorithm, potential treatment misclassification, and non-availability of prognostic factors including disease staging information, biomarkers, and other laboratory variables. Additional analyses are warranted to understand the relationship between treatments and death.

Men have been found to attribute more sexual meaning to cross-gender interactions than women do--a finding that has come to be known as the oversexualization effect. Despite the large body of research supporting the notion that men are more biased in their perceptions than women, researchers are moving beyond gender differences and examining personality variables to identify factors that can explain and predict the oversexualization effect. However, results have been mixed. Thus, the goal of this study was to develop a measurement tool, the Sexual Intent Scale, which assesses individual differences in attributing sexual intent. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) of the Sexual Intent Scale revealed the scale has three components we termed Sexual Facility, Friendship Facility, and Sexual Empathy. Temporal reliability and convergent and construct validity as well as norms and subscale correlations are presented. Results are discussed in terms of the scale's utility and directions for future research are explored.

Purpose: In July 2007, the Centers for Medicare & Medicaid Services released a national coverage determination (NCD) for erythropoiesis-stimulating agent (ESA) use in cancer patients, mandating payment restrictions likely to reduce ESA use and possibly increase red blood cell transfusions. We aimed to quantify ESA and transfusion use pre-NCD and post-NCD., Methods: Medicare 5% sample data, 2005-2007, were used. Patients were 66 years or older, had lung, breast, or colorectal cancer or lymphomas, and initiated chemotherapy in pre-NCD and post-NCD periods (September-November 2006, September-November 2007). ESA use and transfusions were identified from claims. Differences in proportions of patients using ESAs and receiving transfusions pre-NCD and post-NCD were evaluated using logistic regression; differences in transfusion event rates were evaluated using a Poisson model., Results: The pre-NCD cohort included 1897 patients and the post-NCD cohort 1877. In the pre-NCD cohort, 31% of patients had lung cancer, 29% lymphoma, 20% colorectal cancer, and 20% breast cancer; distribution was similar in the post-NCD cohort. Overall, ESA use decreased from 35.0% pre-NCD to 15.2% post-NCD. Transfusion use increased from 9.3% to 10.4%, and transfusion event rates from 19.0 to 21.8 per 100 patient-quarters. Results adjusted for baseline characteristics and comorbid conditions were similar. ESA use reduction achieved statistical significance; transfusion use and rate increases did not., Conclusions: ESA use decreased sharply post-NCD. This was accompanied by an estimated 1.1% (95% confidence interval -0.8% to 3.0%) absolute increase in transfusion use., (Copyright © 2012 John Wiley & Sons, Ltd.)

We previously demonstrated that inhaling nitric oxide (NO) increases the oxygen affinity of sickle red blood cells (RBCs) in patients with sickle cell disease (SCD). Our recent studies found that NO lowered the P(50) values of sickle hemoglobin (HbS) hemolysates but did not increase methemoglobin (metHb) levels, supporting the role of NO, but not metHb, in the oxygen affinity of HbS. Here we examine the mechanism by which NO increases HbS oxygen affinity. Because anti-sickling agents increase sickle RBC oxygen affinity, we first determined whether NO exhibits anti-sickling properties. The viscosity of HbS hemolysates, measured by falling ball assays, increased upon deoxygenation; NO treatment reduced the increment. Multiphoton microscopic analyses showed smaller HbS polymers in deoxygenated sickle RBCs and HbS hemolysates exposed to NO. These results suggest that NO inhibits HbS polymer formation and has anti-sickling properties. Furthermore, we found that HbS treated with NO exhibits an isoelectric point similar to that of HbA, suggesting that NO alters the electric charge of HbS. NO-HbS adducts had the same elution time as HbA upon high performance liquid chromatography analysis. This study demonstrates that NO may disrupt HbS polymers by abolishing the excess positive charge of HbS, resulting in increased oxygen affinity., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Intracellular levels of the light (L) and heavy (H) ferritin subunits are regulated by iron at the level of message translation via a modulated interaction between the iron regulatory proteins (IRP1 and IRP2) and a 5'-untranslated region. Iron-responsive element (IRE). Here we show that iron and interleukin-1beta (IL-1beta) act synergistically to increase H- and L-ferritin expression in hepatoma cells. A GC-rich cis-element, the acute box (AB), located downstream of the IRE in the H-ferritin mRNA 5'-untranslated region, conferred a substantial increase in basal and IL-1beta-stimulated translation over a similar time course to the induction of endogenous ferritin. A scrambled version of the AB was unresponsive to IL-1. Targeted mutation of the AB altered translation; reverse orientation and a deletion of the AB abolished the wild-type stem-loop structure and abrogated translational enhancement, whereas a conservative structural mutant had little effect. Labeled AB transcripts formed specific complexes with hepatoma cell extracts that contained the poly(C)-binding proteins, iso-alphaCP1 and -alphaCP2, which have well defined roles as translation regulators. Iron influx increased the association of alphaCP1 with ferritin mRNA and decreased the alphaCP2-ferritin mRNA interaction, whereas IL-1beta reduced the association of alphaCP1 and alphaCP2 with H-ferritin mRNA. In summary, the H-ferritin mRNA AB is a key cis-acting translation enhancer that augments H-subunit expression in Hep3B and HepG2 hepatoma cells, in concert with the IRE. The regulated association of H-ferritin mRNA with the poly(C)-binding proteins suggests a novel role for these proteins in ferritin translation and iron homeostasis in human liver.

This study sought to clarify previous research in the face recognition literature regarding memory for faces with spectacles. A second aim of this research was to further investigate Valentine's face-space model, a leading model of face recognition that predicts better performance on distinctive faces compared to typical faces. Prior to this experiment, independent observers provided distinctiveness ratings for faces with, and without, spectacles. Experimental participants then accessed the PsychExperiments website and completed a face recognition experiment. Based on the judgments of the independent observers, the face-space model predicts that memory for spectacled faces should be superior to memory for non-spectacled faces. An analysis of hit rate (percent correct) supported this notion, as a higher hit rate was observed for spectacled faces compared to non-spectacled faces. However, the analysis of false alarms (false identifications) did not support the predictions made by the face-space model, as participants demonstrated reliably higher false alarm rates for faces with spectacles. A further analysis of response bias suggests that the overall pattern of responding may have been largely due to changes in response criteria for trials where spectacled faces were presented. Implications for models of face recognition are discussed.

The Fear Survey Schedule-III (FSS-III) was administered to a total of 5491 students in Australia, East Germany, Great Britain, Greece, Guatemala, Hungary, Italy, Japan, Spain, Sweden, and Venezuela, and submitted to the multiple group method of confirmatory analysis (MGM) in order to determine the cross-national dimensional constancy of the five-factor model of self-assessed fears originally established in Dutch, British, and Canadian samples. The model comprises fears of bodily injury-illness-death, agoraphobic fears, social fears, fears of sexual and aggressive scenes, and harmless animals fears. Close correspondence between the factors was demonstrated across national samples. In each country, the corresponding scales were internally consistent, were intercorrelated at magnitudes comparable to those yielded in the original samples, and yielded (in 93% of the total number of 55 comparisons) sex differences in line with the usual finding (higher scores for females). In each country, the relatively largest sex differences were obtained on harmless animals fears. The organization of self-assessed fears is sufficiently similar across nations to warrant the use of the same weight matrix (scoring key) for the FSS-III in the different countries and to make cross-national comparisons feasible. This opens the way to further studies that attempt to predict (on an a priori basis) cross-national variations in fear levels with dimensions of national cultures.

The 34-item Social Support List developed in The Netherlands combines measures of support satisfaction and support interactions in six subscales plus a total score. The present study was designed to assess the applicability of the list in a different cultural context. Data from 421 American undergraduates were consistent with Dutch findings and support the efficacy of the English language version.

The Scale for Interpersonal Behaviour (SIB), a multidimensional, self-report measure of state assertiveness, was administered to a nationwide sample of 2375 undergraduates enrolled at 11 colleges and universities across the USA. The SIB was developed in the Netherlands for the independent assessment of both distress associated with self-assertion in a variety of social situations and the likelihood of engaging in a specific assertive response. This is done with four factorially-derived, first-order dimensions: (i) Display of negative feelings (Negative assertion); (ii) Expression of and dealing with personal limitations; (iii) Initiating assertiveness; and (iv) Praising others and the ability to deal with compliments/praise of others (Positive assertion). The present study was designed to determine the cross-national invariance of the original Dutch factors and the construct validity of the corresponding dimensions. It also set out to develop norms for a nationwide sample of US students. The results provide further support for the reliability, factorial and construct validity of the SIB. Compared to their Dutch equivalents, US students had meaningfully higher distress in assertiveness scores on all SIB scales (medium to large effect sizes), whereas differences on the performance scales reflected small effect sizes. The cross-national differences in distress scores were hypothesized to have originated from the American culture being more socially demanding with respect to interpersonal competence than the Dutch, and from the perceived threats and related cognitive appraisals that are associated with such demands.

Purpose: We determined whether the cytotoxicity of doxorubicin hydrochloride would be enhanced by adding hydrogen peroxide as a source of oxygen free radicals., Materials and Methods: Mouse bladder tumor cells (MBT-2) were grown in RPMI 1640 medium and treated with various concentrations of doxorubicin hydrochloride for 2 hours. Protein content was assayed as a measure of cell growth. A similar set of experiments was done with cells exposed to hydrogen peroxide only and combined doxorubicin and hydrogen peroxide. Protein content was again assayed as a measure of cell growth. Cells were also assayed for glutathione peroxidase and malonyl dialdehyde, a product of lipid peroxidation, to determine the mechanism of cell damage. Furthermore, MBT-2 cells were incubated with 100 M. alpha-tocopherol, a free radical scavenger, before exposure to hydrogen peroxide to determine whether the effects of hydrogen peroxide could be reversed., Results: We observed a dose dependent inhibition of MBT-2 cell growth after exposure to doxorubicin hydrochloride. Exposure to doxorubicin and hydrogen peroxide resulted in greater cell growth inhibition than exposure to either agent alone. The effects of hydrogen peroxide on cell proliferation were reversed by pre-incubation with alpha-tocopherol., Conclusions: As a source of oxygen free radicals, hydrogen peroxide enhances the antiproliferative effect of doxorubicin hydrochloride on a mouse bladder tumor cell line. Thus, hydrogen peroxide may be a relatively inexpensive, nontoxic method of augmenting the cytotoxicity of doxorubicin hydrochloride. Further studies are warranted to determine whether these observations may have clinical application.

Chloramphenicol is an antibiotic that consistently suppresses the bone marrow and induces sideroblastic anemia. It is also a rare cause of aplastic anemia. These toxicities are thought to be related to mitochondrial dysfunction, since chloramphenicol inhibits mitochondrial protein synthesis. We hypothesized that chloramphenicol-induced mitochondrial impairment alters the synthesis of ferritin and the transferrin receptor. After treating K562 erythroleukemia cells with a therapeutic dose of chloramphenicol (10 microg/ml) for 4 days, there was a marked decrease in cell surface transferrin receptor expression and de novo ferritin synthesis associated with significant decreases in cytochrome c oxidase activity, ATP levels, respiratory activity, and cell growth. Decreases in the transferrin receptor and ferritin were associated with reduced and unchanged message levels, respectively. The mechanism by which mitochondrial dysfunction alters these important proteins in iron homeostasis is not clear. A global decrease in synthetic processes seems unlikely, since the expression of the cellular adhesion proteins VLA4 and CD58 was not significantly decreased by chloramphenicol, nor were the message levels of beta-actin or ferritin. The alterations were not accompanied by changes in binding of the iron response protein (IRP) to the iron-responsive element (IRE), although cytosolic aconitase activity was reduced by 27% in chloramphenicol-treated cells. A disturbance in iron homeostasis due to alterations in the transferrin receptor and ferritin may explain the hypochromic-microcytic anemia and the accumulation of nonferritin iron in the mitochondria in some individuals after chloramphenicol therapy. Also, these studies provide evidence of a link between mitochondrial impairment and iron metabolism in K562 cells.

Ferritin and transferrin receptor expression is post-transcriptionally regulated by a conserved mRNA sequence termed the iron-responsive element (IRE), to which a transacting protein called the iron-regulatory protein (IRP) is bound. Our data demonstrate that hypoxia powerfully enhances IRE/IRP-1 binding in human cell lines. Using the human hepatoma cell line Hep3B as a model, we found that 16 h in a 1% oxygen atmosphere markedly increases IRE/IRP-1 binding as assessed by electromobility shift assay. Hypoxia also decreased cytosolic aconitase activity. The hypoxia-enhanced IRE/IRP-1 binding stabilized the transferrin receptor message, increased the cellular mRNA content by over 10-fold, and doubled surface receptor expression. Simultaneously, hypoxia suppressed ferritin message translation. Hypoxia's effect was most strikingly depicted by the absence of ferritin synthesis in cells challenged with inorganic iron. Our results contrast with previously reported data (Hanson, E. S., and Leibold, E. A. (1998) J. Biol. Chem. 273, 7588-7593) in which a 3% oxygen atmosphere reduced IRE/IRP-1 binding in rat hepatoma cells. We discuss some possible reasons for the differences. In aggregate with other investigations involving responses to hypoxia, iron, or nitric oxide, our data indicate that cellular iron metabolic responses are complex and that IRE/IRP-1 interactions vary between cell lines and perhaps between species.

The hallmark of sickle cell disease (SCD) is the polymerization of deoxygenated sickle hemoglobin (HbS). In SCD patients, one strategy to reduce red blood cell (RBC) sickling is to increase HbS oxygen affinity. Our objective was to determine if low concentrations of nitric oxide (NO) gas would augment the oxygen affinity of RBCs containing homozygous HbS (SS). Blood containing normal adult hemoglobin (AA) or SS RBCs was incubated in vitro in the presence of varying concentrations of NO up to 80 ppm, and oxygen dissociation curves (ODCs) were measured. In addition, blood was obtained from three AA and nine SS volunteers, before and after breathing 80 ppm NO in air for 45 min, and the ODCs were measured. Exposure of SS RBCs to 80 ppm NO in vitro for 5 min or longer decreased the partial pressure of oxygen at which hemoglobin is 50% saturated with oxygen (P50), an average of 15% (4.8+/-1.7 mmHg mean+/-SE; P < 0.001). The increase in SS RBC oxygen affinity correlated with the NO concentration. The P50 of AA RBCs was unchanged (P > 0.1) by 80 ppm NO. In SS volunteers breathing 80 ppm NO for 45 min, the P50 decreased (P < 0.001) by 4.6+/-2.0 mmHg. 60 min after NO breathing was discontinued, the RBC P50 remained decreased in five of seven volunteers in whom the ODC was measured. There was no RBC P50 change (P > 0.1) in AA volunteers breathing NO. Methemoglobin (Mhb) remained low in all subjects breathing NO (SS Mhb 1.4+/-0.5%), and there was no correlation (r = 0.02) between the reduction in P50 and the change in Mhb. Thus, low concentrations of NO augment the oxygen affinity of sickle erythrocytes in vitro and in vivo without significant Mhb production. These results suggest that low concentrations of NO gas may offer an attractive new therapeutic model for the treatment of SCD.

We have used quantitative fluorescence microscopy and fluorescence photobleaching recovery to examine the role of metabolic energy in the translational movement of transferrin receptors in the plasma membrane of K562 erythroleukemia cells. Cellular ATP depletion caused a significant decrease in the translational mobility of cell surface transferrin receptors and a significant increase in the number of receptors on the cell surface. ATP repletion restored receptor translational mobility and cell surface expression to control values. Inhibition of ATP hydrolases by orthovanadate also immobilized cell surface transferrin receptors and altered cell surface receptor expression, in a concentration-dependent manner. Vanadate-induced changes in receptor mobility and cell surface expression were reversible upon washing out the drug. Cellular ATP depletion did not affect the translational mobility of plasma membrane glycophorins or a fluorescent phospholipid analogue. We conclude that the translational movement of cell surface transferrin receptors specifically requires metabolic energy and ATP hydrolysis.

Replenishment of ascorbate in cultured cells, which are almost uniformly vitamin-deficient, increases ferritin mRNA translation in response to iron by 20-fold (Toth, I., Rogers, J. T., McPhee, J. A., Elliott, S. M., Abramson, S. L., and Bridges, K. R. (1995) J. Biol. Chem. 270, 2846-2852). We now demonstrate that ascorbate increases cytosolic aconitase activity. The iron-responsive element-binding protein (IRP-1) exists in three states: bound to mRNA without aconitase activity, free in the cytosol without aconitase activity, and free in the cytosol with aconitase activity. Ascorbate converts free IRP-1 to the enzymatically active form. Enhanced ferritin synthesis with subsequent iron stimulation is due to the altered equilibrium of the free IRP-1. The cellular biology of iron is closely intertwined with that of ascorbate.

Ascorbate is an important cofactor in many cellular metabolic reactions and is intimately linked to iron homeostasis. Continuously cultured cells are ascorbate deficient due to the lability of the vitamin in solution and to the fact that daily supplementation of media with ascorbate is unusual. We found that ascorbate repletion alone did not alter ferritin synthesis. However, ascorbate-replete human hepatoma cells, Hep3B and HepG2, as well as K562 human leukemia cells achieved a substantially higher cellular ferritin content in response to a challenge with iron than did their ascorbate-deficient counterparts grown under standard culture conditions. Most of the elevation in ferritin content was due to an increase in de novo ferritin synthesis of greater than 50-fold, as shown by in vivo labeling with [35S]methionine and immunoprecipitation. RNA-blot analysis showed only minor changes in steady state levels of ferritin mRNA, suggesting that ascorbate enhances iron-induced ferritin synthesis primarily by post-transcriptional events. Transient gene expression experiments using chloramphenicol acetyltransferase reporter gene constructs showed that the ascorbate effect on ferritin translation is not mediated through the stem-loop near the translational start site that transduces ferritin synthesis in response to cytokines. The data suggest that ascorbate possibly modifies the action of the iron-responsive element on ferritin translation, although more precise structure-function studies are needed to clarify this issue. These data demonstrate a novel role of ascorbate as a signaling molecule in post-transcriptional gene regulation. The mechanism by which ascorbate modulates cellular iron metabolism is complex and requires additional detailed investigation.

We used quantitative fluorescence microscopy and fluorescence photobleaching recovery techniques to investigate the translational movement, cell surface expression, and endocytosis of transferrin receptors in K562 human erythroleukemia cells. Receptors were labeled with fluorescein-conjugated transferrin (FITC-Tf). Coordinated decreases in surface fluorescence counts, the photobleaching parameter K, and transferrin receptor fractional mobility were observed as FITC-Tf was cleared from the cell surface by receptor-mediated endocytosis. Based on the kinetics of decrease in these parameters, first order rate constants for FITC-Tf uptake at 37 degrees C and 21 degrees C were calculated to be 0.10-0.15 min-1 and 0.02-0.03 min, respectively. K562 cells were treated with colchicine or vinblastine to investigate the role of microtubules in transferrin receptor movement and endocytosis. Treatment of cells for 1 hr with a microtubule inhibitor prevented transferrin receptor endocytosis but had no effect on the translational mobility of cell surface receptors. In contrast, drug treatment for 3 hr caused translational immobilization of cell surface receptors as well as inhibition of endocytosis. These effects were not produced by beta-lumicolchicine, an inactive colchicine analog, or by cytochalasin, a microfilament inhibitor. The effect of microtubule inhibitors on transferrin receptor mobility was reversed by pretreating cells with taxol, a microtubule-stabilizing agent. Microtubule inhibitors had no effect on the translational mobility of cell surface glycophorins or phospholipids, indicating that intact microtubules were not required for translational movement of these molecules. We conclude that the translational movement of cell surface transferrin receptors is directed by a subpopulation of relatively drug-resistant microtubules. In contrast, transferrin receptor endocytosis depends on a subpopulation of microtubules that is relatively sensitive to the action of inhibitors. These results appear to demonstrate at least two functional roles for microtubules in receptor-mediated transferrin uptake in K562 cells.

Interleukin-1 beta (Il-1 beta), a key cytokine in the acute phase response, elevates hepatic expression of both the heavy (H) and light (L) ferritin subunits without influencing the steady-state levels of either ferritin transcript. Transfection experiments with human hepatoma cells reveal that sequences within the 5' untranslated region (5'UTR) of H-ferritin mRNA confer translational regulation to chimaeric chloramphenicol acetyl transferase (CAT) mRNAs in response to Il-1 beta in the absence of marked changes in CAT mRNA levels. Il-1 beta dependent translational enhancement is mediated by a distinct G + C rich RNA sequence within 70 nucleotides (nt) of the start codon. The upstream Iron Responsive Element RNA stemloop does not confer increased expression to CAT mRNA in Il-1 beta stimulated hepatoma transfectants. A 38 nucleotide consensus sequence within the 5'UTRs of the mRNAs encoding the hepatic acute phase proteins alpha 1-antitrypsin (alpha 1AT), alpha 1-acid glycoprotein (AGP) and haptoglobin (Dente et al., 1985) is similar to sequences in the G + C rich H-ferritin mRNA translational regulatory element. Deletion of three nucleotides from this region of the 61 nt G + C rich element in the H-ferritin mRNA 5' leader eliminates Il-1 beta translational enhancement of the CAT reporter transcripts.

Interleukin-1 (IL-1 beta) increases the synthesis of both heavy and light (L)-ferritin subunits when added to human hepatoma cells (HepG2) grown in culture. RNase protection and Northern blot analysis with L-ferritin probes revealed that no changes in L-ferritin mRNA levels occur after cytokine stimulation. However, the induction coincides with an increased association of the L-subunit mRNA with polyribosomes. Since the recruitment of stored ferritin mRNA onto polyribosomes is seen when iron enters the cell, the effect of IL-1 beta on iron uptake was tested and was found to be unaffected by the lymphokine. Neither transferrin receptor mRNA levels nor the number of receptors displayed on the cell surface was affected by IL-1 beta. However, the action of the cytokine on ferritin translation is inhibited by the action of the intracellular iron chelator deferoxamine. These data indicate that IL-1 beta induces ferritin gene expression by translational control of its mRNA. The pathway of induction is different from iron-dependent ferritin gene expression whereas regulation requires the background presence of cellular iron.

At physiological temperature, the Fe-carrier transferrin is taken up by K562 human erythroleukemia cells through receptor-mediated endocytosis. Both ligand (now minus Fe) and receptor recycle back to the cell surface where the receptor is rapidly reutilized. After endocytosis, transferrin becomes transiently lodged within an acidic compartment inside the cell, as judged by the changed spectral characteristics and quantum yield of fluorescein isothiocyanate-labeled transferrin that is cell-associated at 37 degrees C. Upon binding to transferrin, anti-fluorescein antibody strongly quenches the emission of the fluorescein-labeled residues on the protein and is used to assess whether the transferrin is at the cell surface (incubation at 0 degrees C) or mainly internalized into the cell (incubation at 37 degrees C). Using Percoll gradient fractionation of postnuclear supernatants, we show that the acidic compartment is not the lysosomal compartment.

Delivery of iron to K562 cells by diferric transferrin involves a cycle of binding to surface receptors, internalization into an acidic compartment, transfer of iron to ferritin, and release of apotransferrin from the cell. To evaluate potential feedback effects of iron on this system, we exposed cells to iron chelators and monitored the activity of the transferrin receptor. In the present study, we found that chelation of extracellular iron by the hydrophilic chelators desferrioxamine B, diethylenetriaminepentaacetic acid, or apolactoferrin enhanced the release from the cells of previously internalized 125I-transferrin. Presaturation of these compounds with iron blocked this effect. These chelators did not affect the uptake of iron from transferrin. In contrast, the hydrophobic chelator 2,2-bipyridine, which partitions into cell membranes, completely blocked iron uptake by chelating the iron during its transfer across the membrane. The 2,2-bipyridine did not, however, enhance the release of 125I-transferrin from the cells, indicating that extracellular iron chelation is the key to this effect. Desferrioxamine, unlike the other hydrophilic chelators, can enter the cell and chelate an intracellular pool of iron. This produced a parallel increase in surface and intracellular transferrin receptors, reaching 2-fold at 24 h and 3-fold at 48 h. This increase in receptor number required ongoing protein synthesis and could be blocked by cycloheximide. Diethylenetriaminepentaacetic acid or desferrioxamine presaturated with iron did not induce new transferrin receptors. The new receptors were functionally active and produced an increase in 59Fe uptake from 59Fe-transferrin. We conclude that the transferrin receptor in the K562 cell is regulated in part by chelatable iron: chelation of extracellular iron enhances the release of apotransferrin from the cell, while chelation of an intracellular iron pool results in the biosynthesis of new receptors.

Ascorbic acid retards ferritin degradation in K562 erythroleukemia cells leading to an increase in the availability of cellular iron (Bridges, K. R., and Hoffman, K. E. (1986) J. Biol. Chem. 261, 14273-14277). To explore the mechanism of this effect, the influence of ascorbate on subcellular ferritin distribution was examined. Cellular ferritin was pulse-labeled with 59Fe for 2 h, after which the cells were hypotonically lysed and fractionated on an 8% Percoll density gradient. Immediately after the labeling, all of the ferritin was in the cytoplasmic fractions at the top of the gradient. When the labeling was followed by a 24-h period of growth, a portion of the ferritin shifted to the lysosome-associated fractions at the bottom of the gradient, consistent with lysosomal autophagy of cytoplasmic ferritin. When ascorbate was added to the culture medium during the 24-h incubation, the magnitude of the shift was reduced. This process was also examined by size-fractionation of the contents of labeled cells using a Sepharose CL-6B column. Immediately after labeling, ferritin emerged from the column in two peaks, indicating the existence of both ferritin monomer and aggregates within the cytoplasm. After a 24-h period of growth, the monomer peak disappeared, while a new ferritin peak coincident with lysosomes emerged again, indicative of lysosomal autophagy of ferritin. In cells cultured with ascorbate for 24-h, there was a marked attenuation of the shift of ferritin to the lysosomal fractions. The monomer peak disappeared, as in the controls, but there was instead, an accumulation of ferritin as cytoplasmic aggregates. The total ferritin content of the ascorbate-treated cells was increased by 4-fold over that of the control. These experiments indicate that ascorbate blocks the degradation of cytoplasmic ferritin by reducing lysosomal autophagy of the protein. The access to the cell of the potentially toxic iron stored within the ferritin molecule is thereby increased.

Expression of the transferrin receptor on target cell lines has recently been implicated as a determinant of susceptibility to cytolysis by natural killer (NK) lymphocytes. We have examined this proposed relationship in several ways. First, K562 (a cell line highly vulnerable to NK lysis) cells were grown for 24 h in the iron chelator desferrioxamine. Under these conditions, the cells doubled their surface transferrin receptor expression as determined both by radioligand binding and surface binding of the OK-T9 monoclonal anti-transferrin receptor antibody. In contrast, cells grown for the same period of time in hemin halved their receptor expression. This fourfold change in transferrin receptor expression between the desferrioxamine-treated and hemin-treated cells produced no change in susceptibility to NK cytolysis. Second, HeLa (a cell line which in its native state is very resistant to NK cytolysis) cells were compared with K562 cells with respect to surface transferrin receptor expression. The difference in NK susceptibility of the two cell lines was not reflected in differences in transferrin receptor expression: the K562 cells expressed approximately 1.5 X 10(5) receptors per cell while HeLa cells expressed 2.0 X 10(5) receptors/cell. Third, infection of HeLa cells by measles virus greatly increased their susceptibility to NK lysis but produced no change in surface transferrin receptor expression. Furthermore, when measles-infected HeLa cells were grown for 6 d in medium supplemented with iron-saturated human transferrin they underwent a 50% reduction in receptor expression but no change in NK susceptibility. Finally, possible alterations in the surface expression of NK target antigens on modified cells were further assayed by their ability to serve as cold-target inhibitors of cytolysis of NK-sensitive target cells. We examined two groups of cells in which transferrin receptor expression was reduced. These were the transferrin-treated, measles-infected HeLa cells with the 50% receptor reduction, and K562 cells grown in medium containing hemin and iron salts where the reduction was five- to sixfold relative to control. In neither case was there a change in the apparent expression of NK target antigen(s). We conclude that there is a discordance between transferrin receptor expression and susceptibility to NK cytolysis in the model systems examined. Therefore, it is unlikely that the transferrin receptor per se is the target recognition structure for human NK cells, although a role in concert with other, as yet undefined molecules, cannot be excluded.

The binding of apotransferrin to the transferrin receptor on the surface of human leukemic K562 cells was found to be significantly less tight than that of the holoprotein, diferric transferrin. The finding that both ligands displayed linear Scatchard plots with similar receptor number (approximately equal to 150,000 per cell) and mutually inhibit each other's binding suggested that they bind to the same receptor. Both the dissociation and association rate of apotransferrin were markedly increased (28-fold and 15-fold, respectively) at pH 7.2 compared to pH 4.8. Using the values of these binding parameters, we propose a mechanism to account for the recycling of transferrin subsequent to internalization and residence within an acidic nonlysosomal organelle where iron is removed.

Problem and nonproblem drinking, college student sons of alcoholics were compared to problem and nonproblem drinking college student sons of nonalcoholic fathers with respect to cognitive functioning. Problem drinkers performed more poorly on two of the four cognitive tasks, Group Embedded Figures and Symbol-Digit Paired Associates Learning Task, thus supporting earlier findings of cognitive deficits in problem drinking nonalcoholics. Additionally, sons of alcoholics tended to perform more poorly than sons of nonalcoholics on the Group Embedded Figures Test. Cognitive performance was not predicted by any of four measures of impulsive/antisocial personality and behavior-preadult antisocial behavior, childhood behavior problems, sensation seeking, and the MacAndrew Alcoholism Scale. The findings of the research pointed to the importance of considering both drinking and familial alcoholism risk statuses in studies of the cognitive performance of nonalcoholics. Further implications and limitations of the findings are discussed.

An important property of ascorbic acid is its ability to increase the availability of storage iron to chelators. To examine the mechanism of this effect, K562 cells were incubated with ascorbate, attaining an intracellular level of 1 nmol/10(7) cells. In contrast to the reductive mobilization of iron seen with isolated ferritin, ascorbate stabilized iron preincorporated into cellular ferritin. Biosynthetic labeling with [35S]methionine demonstrated that ascorbate also retarded the degradation of the ferritin protein shell. Ferritin is normally degraded in lysosomes. The lysosomal protease inhibitors leupeptin and chloroquine produced a qualitatively similar stabilization of ferritin. Ascorbate did not act as a general inhibitor of proteolysis, however, since it did not effect hemoglobin degradation in these cells. The stabilization of cellular ferritin by ascorbate was accompanied by an expansion of the pool of chelatable iron.

Seventeen high risk and seventeen low risk college-aged men were compared with respect to drinking behavior/problems and certain implicated personality characteristics. The low risk subjects were, surprisingly, found to drink and become intoxicated more frequently than high risk subjects. They also reported significantly higher sensation seeking scores. This latter variable accounted for the greatest amount of variance in both risk status and frequency of drinking. By contrast, high risk subjects reported somewhat more lifetime alcohol-related symptomatology and significantly more preadult antisocial symptoms. Preadult antisocial symptoms, alone, explained 39% and 29%, respectively, of the variance in alcohol-related symptoms and the amount consumed on a typical drinking day. The implications and limitations of the findings with respect to the development of alcoholism are discussed.

Human diferric transferrin binds to the surface of K562 cells, a human leukemic cell line. There are about 1.6 X 10(5) binding sites per cell surface, exhibiting a KD of about 10(-9) M. Upon warming cells to 37 degrees C there is a rapid increase in uptake to a steady state level of twice that obtained at 0 degree C. This is accounted for by internalization of the ligand as shown by the development of resistance to either acid wash or protease treatment of the ligand-cell association. After a minimum residency time of 4-5 min, undegraded transferrin is released from the cell. Internalization is rapid but is dependent upon cell surface occupancy; at occupancies of 20% or greater the rate coefficient is maximal at about 0.1-0.2 min-1. In the absence of externally added ligand only 50% of the internalized transferrin completes the cycle and is released to the medium with a rate coefficient of 0.05 min-1. The remaining transferrin can be released from the cell only by the addition of ligand, suggesting a tight coupling between cell surface binding, internalization, and release of internalized ligand. There is a loss of cell surface-binding capacity that accompanies transferrin internalization. At low (less than 50%) occupancy this loss is monotonic with the extent of internalization. Even at saturating levels of transferrin, the loss of surface receptors upon internalization never exceeds 60-70% of the initial binding capacity. This suggests that receptors enter the cell with ligand but are replaced so as to maintain a constant, albeit reduced, receptor number on the cell surface. In the absence of ligand, the cell surface receptor number returns at 37 degrees C. Neither sodium azide nor NH4Cl blocks internalization of ligand. However, they both prevent the release of transferrin from the cell thus halting the transferrin cycle. Excess ligand can overcome the block due to NH4Cl but not azide although the cycle is markedly slower. Iron is delivered to these cells by transferrin at 37 degrees C with a rate coefficient of 0.15 to 0.2 min-1. The iron is released from the transferrin and the majority is found in intracellular ferritin. There is a large internal receptor pool comprising 70 to 80% of the total cell receptors and this may be involved in maintaining the steady state iron uptake.

Iron delivery to K562 cells is enhanced by desferrioxamine through induction of transferrin receptors. Experiments were performed to further characterize this event with respect to iron metabolism and heme synthesis. In control cells, up to 85% of the iron taken up from iron-transferrin was incorporated into ferritin, 7% into heme, and the remainder into compartments not yet identified. In cells grown with desferrioxamine, net accumulation of intracellular desferrioxamine (14-fold) was observed and iron incorporation into ferritin and heme was inhibited by 86% and 75%, respectively. In contrast, complete inhibition of heme synthesis in cells grown with succinylacetone had no effect on transferrin binding or iron uptake. Exogenous hemin (30 microM) inhibited transferrin binding and iron uptake by 70% and heme synthesis by 90%. These effects were already evident after 2 h. Thus, although heme production could be reduced by desferrioxamine, succinylacetone, and hemin, cell iron uptake was enhanced only by the intracellular iron chelator. The effects of exogenous heme are probably unphysiologic and the greater inhibition of iron flow into heme can be explained by effects on early steps of heme synthesis. We conclude that in this cell model a chelatable intracellular iron pool rather than heme synthesis mediates regulation of iron uptake.

The chemical modification of hemoglobin by aspirin (ASA) has been studied, both in intact human red cells and in purified hemoglobin solutions. After incubation of red cells with 20 mM [acetyl-1minus14C]ASA, incorporation of radioactivity into hemoglobin was observed in agreement with the results of Klotz and Tam (1973. Proc. Natl. Acad. Sci. U. S. A. 70: 1313-1315). In contrast, no labeling of hemoglobin was seen when [carbosyl-14-C]ASA was used. These results indicate that ASA acetylates hemoglobin. The acetylated hemoglobin was readily separated from unmodified hemoglobin by both gel electrofocusing and by column chromatography. Quantitation of the extent of acetylation by densitometric scanning of gels agreed very well with estimates obtained from radioactivity measurements. Hemolysates prepared from red cells incubated with ASA showed normal oxygen affinity and heme-heme interaction. Purified acetylated hemoglobin had a slightly increased oxygen affinity and decreased heme-heme interaction. There was no difference in the rate of acetylation of oxy- and deoxyhemoglobin. ASA acetylated column-purified hemoglobin A more readily than hemoglobin in crude hemolysate, but less rapidly than purified human serum albumin. The rate of acetylation of hemoglobulin increased with pH up to approximately pH 8,5. Structural studies were done on hemoglobin incubated with 2.0 mM and 20 mM [acetyl-1-14-C]ASA. Alpha- and beta-chains were acetylated almost equally. Tryptic digests of purified acetylated subunits were fingerprinted on cellulose thin layer plates and autoradiographed. Both alpha- and beta-chains showed a number of radioactive spots that were either ninhydrin negative or weakly ninhydrin positive. These results indicate that hemoglobin is acetylated at a number of sites, probably at the epislon-amino group of lysine residues. To determine whether ASA acetylates hemoglobin in vivo, hemolysates of 14 patients on long-term high-dose ASA therapy were analyzed by gel electrofocusing and compared to specimens of individuals not receiving ASA. The ASA-treated group had a twofold increase in a minor hemoglobin component having an isoelectric point lower than that of hemoglobin A, and indistinguishable from the minoe component which appears when hemoglobin is incubated with ASA in vitro.