Relationship of depression to increased risk of mortality and rehospitalization in patients with congestive heart failure

BACKGROUND

Patients with congestive heart failure (CHF) may have a high prevalence of depression, which may increase the risk of adverse outcomes.

OBJECTIVE

To determine the prevalence and relationship of depression to outcomes of patients hospitalized with CHF.

METHODS

We screened patients aged 18 years or older having New York Heart Association class II or greater CHF, an ejection fraction of 35% or less, or both, admitted between March 1, 1997, and June 30, 1998, to the cardiology service of one hospital. Patients with a Beck Depression Inventory score of 10 or higher underwent a modified National Institute of Mental Health Diagnostic Interview Schedule to identify major depressive disorder. Primary care providers coordinated standard treatment for CHF and other medical and psychiatric disorders. We assessed all-cause mortality and readmission (rehospitalization) rates 3 months and 1 year after depression assessment. Logistic regression analyses were used to evaluate the independent prognostic value of depression after adjustment for clinical risk factors.

RESULTS

Of 374 patients screened, 35.3% had a Beck Depression Inventory score of 10 or higher and 13.9% had major depressive disorder. Overall mortality was 7.9% at 3 months and 16.2% at 1 year. Major depression was associated with increased mortality at 3 months (odds ratio, 2.5 vs no depression; P =.08) and at 1 year (odds ratio, 2.23; P =.04) and readmission at 3 months (odds ratio, 1.90; P =.04) and at 1 year (odds ratio, 3.07; P =.005). These increased risks were independent of age, New York Heart Association class, baseline ejection fraction, and ischemic etiology of CHF.

CONCLUSIONS

Major depression is common in patients hospitalized with CHF and is independently associated with a poor prognosis.

Fluid particle accelerations in fully developed turbulence

The motion of fluid particles as they are pushed along erratic trajectories by fluctuating pressure gradients is fundamental to transport and mixing in turbulence. It is essential in cloud formation and atmospheric transport, processes in stirred chemical reactors and combustion systems, and in the industrial production of nanoparticles. The concept of particle trajectories has been used successfully to describe mixing and transport in turbulence, but issues of fundamental importance remain unresolved. One such issue is the Heisenberg-Yaglom prediction of fluid particle accelerations, based on the 1941 scaling theory of Kolmogorov. Here we report acceleration measurements using a detector adapted from high-energy physics to track particles in a laboratory water flow at Reynolds numbers up to 63,000. We find that, within experimental errors, Kolmogorov scaling of the acceleration variance is attained at high Reynolds numbers. Our data indicate that the acceleration is an extremely intermittent variable--particles are observed with accelerations of up to 1,500 times the acceleration of gravity (equivalent to 40 times the root mean square acceleration). We find that the acceleration data reflect the anisotropy of the large-scale flow at all Reynolds numbers studied.

Development of high potency universal DR-restricted helper epitopes by modification of high affinity DR-blocking peptides

Pan DR-binding peptides engineered by introducing anchor residues for different DR motifs within a polyalanine backbone bound 10 of 10 DR molecules tested, with affinities, in most cases, in the nanomolar range. Because of the small methyl group exposed for T cell recognition, these peptides were poor immunogens but effective blockers of DR-restricted antigen presentation. Introduction of bulky and charged residues at positions accessible for T cell recognition yielded extremely powerful Pan DR epitope peptides (PADRE). These peptides elicited powerful responses in vitro from human peripheral blood mononuclear cells (PBMC). Because these cells also cross-react on certain mouse class II alleles, we could also demonstrate that PADRE peptides are active in vivo. In one example of their capacity to elicit T help, they were approximately 1000 times more powerful than natural T cell epitopes. We propose that PADRE peptides may be useful in the development of subunit vaccines.

Antigen analog-major histocompatibility complexes act as antagonists of the T cell receptor

A novel mechanism for inhibition of T cell responses is described. Using the recognition of the influenza hemagglutinin (HA) 307-319 peptide in the context of DR1 class II major histocompatibility complex molecules, we have found that nonstimulatory analogs of the HA peptide preferentially inhibit HA-specific T cells in inhibition of antigen presentation assays. This antigen-specific effect could be generalized to another DR1-restricted peptide, Tetanus toxoid 830-843. Direct binding and cellular experiments indicated that the mechanism responsible was distinct from competition for binding to DR1 molecules. Likewise, negative signaling and induction of T cell tolerance could also be excluded as effector mechanisms. Thus, the most likely mechanism for this effect is engagement of antigen-specific T cell receptors by DR1-peptide analog complexes, which results in antigen-specific competitive blocking of T cell responses by virtue of their capacity to compete with DR1-antigen complexes for binding to the T cell receptor.

Serial assessment of doxorubicin cardiotoxicity with quantitative radionuclide angiocardiography

We measured cardiac performance sequentially, using quantitative radionuclide angiocardiography to estimate left ventricular ejection fraction in 55 patients receiving doxorubicin for treatment of cancer. With final doxorubicin dosages greater than 350 mg per square meter, the lowest ejection fraction measured was significantly less than the initial determination. Five patients had severe cardiotoxicity (congestive heart failure). All had an ejection fraction of less than 30 per cent at the time of heart failure, and demonstrated moderate cardiotoxicity (a decline in ejection fraction by at least 15 per cent to a final value of less than 45 per cent) before clinical manifestations. Six patients with moderate toxicity in whom doxorubicin was discontinued did not have heart failure or a further decline in ejection fraction during the follow-up period. Moderate toxicity was continued, but mild toxicity (decline of ejection fraction by greater than 10 per cent, noted in 11 patients) was not well predicted. The assessment of radionuclide left ventricular ejection fraction during doxorubicin therapy may make it possible to avoid congestive heart failure.

Gata5 is required for the development of the heart and endoderm in zebrafish

The mechanisms regulating vertebrate heart and endoderm development have recently become the focus of intense study. Here we present evidence from both loss- and gain-of-function experiments that the zinc finger transcription factor Gata5 is an essential regulator of multiple aspects of heart and endoderm development. We demonstrate that zebrafish Gata5 is encoded by the faust locus. Analysis of faust mutants indicates that early in embryogenesis Gata5 is required for the production of normal numbers of developing myocardial precursors and the expression of normal levels of several myocardial genes including nkx2.5. Later, Gata5 is necessary for the elaboration of ventricular tissue. We further demonstrate that Gata5 is required for the migration of the cardiac primordia to the embryonic midline and for endodermal morphogenesis. Significantly, overexpression of gata5 induces the ectopic expression of several myocardial genes including nkx2.5 and can produce ectopic foci of beating myocardial tissue. Together, these results implicate zebrafish Gata5 in controlling the growth, morphogenesis, and differentiation of the heart and endoderm and indicate that Gata5 regulates the expression of the early myocardial gene nkx2.5.

Congestive heart failure and left ventricular dysfunction complicating doxorubicin therapy. Seven-year experience using serial radionuclide angiocardiography

To impact on the development of clinical congestive heart failure as a complication of doxorubicin therapy, left ventricular ejection fraction was monitored with serial resting radionuclide angiocardiography in 1,487 patients with cancer over a seven-year period in both university and community hospital environments. A high-risk subset of 282 patients was selected for retrospective analysis of their clinical outcome. High-risk patients were identified by one or two of the following three criteria: decline of 10 percent or more in absolute left ventricular ejection fraction from a normal baseline to 50 percent or less; high cumulative dose of doxorubicin (more than 450 mg/m2); abnormal baseline left ventricular ejection fraction (less than 50 percent). Clinical congestive heart failure occurred in 46 (16 percent) during the treatment period, and in an additional three patients (1.3 percent) at last follow-up examination 11.8 +/- 14.2 months following discontinuation of doxorubicin. Total cumulative dosages of doxorubicin that precipitated congestive heart failure (75 to 1,095 mg/m2) and those that did not (30 to 880 mg/m2) varied widely. Decline of 10 percent or more in absolute left ventricular ejection fraction to a value of 50 percent or less preceded administration of the final dose of doxorubicin that precipitated clinical congestive heart failure in the majority of patients in whom congestive heart failure developed. Clinical congestive heart failure improved in 87 percent given routine therapy with digitalis, diuretics, and/or vasodilators. Criteria for monitoring left ventricular ejection fraction and discontinuing doxorubicin were formulated. The occurrence of clinical congestive heart failure was compared in those patients whose management was concordant with proposed criteria (Group A) and in those whose management was not (Group B). Group A had a lower incidence of congestive heart failure compared with Group B (2.9 percent versus 20.8 percent, p less than 0.001) and had only mild congestive heart failure that resolved with treatment (n = 2) and no deaths due to congestive heart failure. Multivariate analysis with proportional-hazards regression (Cox's model) demonstrated a fourfold reduction in the incidence of congestive heart failure independent of other clinical predictor variables in those patients whose management was concordant with proposed guideline criteria. The incidence, persistence, late development, predictability, and reversibility of clinical congestive heart failure were comparable in university and community hospital settings.(ABSTRACT TRUNCATED AT 400 WORDS)

Lyme carditis: cardiac abnormalities of Lyme disease

We studied 20 patients, mostly young adult men, with cardiac involvement of Lyme disease. The commonest abnormality (18 patients) was fluctuating degrees of atrioventricular block; eight of them developed complete heart block. Thirteen patients had evidence of more diffuse cardiac involvement: electrocardiographic changes compatible with acute myopericarditis (11 patients), radionuclide evidence of mild left ventricular dysfunction (five of 12 patients tested), or frank cardiomegaly (one patient). Heart involvement was usually preceded by erythema chronicum migrans and sometimes accompanied by meningoencephalitis, facial palsy, arthritis, elevated serum IgM levels, or cryoglobulins containing IgM. The duration of cardiac involvement was usually brief (3 days to 6 weeks). The clinical picture in these patients has similarities to acute rheumatic fever; but in Lyme disease, complete heart block may be commoner, myopericardial involvement tends to be milder, and valves seem not to be affected.

Presentation of viral antigen controlled by a gene in the major histocompatibility complex

We describe a mutant human cell line (LBL 721.174) that has lost a function required for presentation of intracellular viral antigens with class I molecules of the major histocompatibility complex (MHC), but retains the capacity to present defined epitopes as extracellular peptides. The cell also has a defect in the assembly and expression of class I MHC molecules, which we show can be restored by exposure of the cells to a peptide epitope. This phenotype suggests a defect in the association of intracellular antigen with class I molecules similar to that described for the murine mutant RMA-S (ref. 5), but in the present case the genetic defect can be mapped within the MHC locus on human chromosome 6.

Sex-associated hormones and immunity to protozoan parasites

Numerous epidemiological and clinical studies have noted differences in the incidence and severity of parasitic diseases between males and females. Although in some instances this may be due to gender-associated differences in behavior, there is overwhelming evidence that sex-associated hormones can also modulate immune responses and consequently directly influence the outcome of parasitic infection. Animal models of disease can often recreate the gender-dependent differences observed in humans, and the role of sex-associated hormones can be confirmed by experimentally altering their levels. Under normal circumstances, levels of sex hormones not only differ between males and females but vary according to age. Furthermore, not only are females of reproductive age subject to the regular hormonal cycles which control ovulation, they are also exposed to dramatically altered levels during pregnancy. It is thus not surprising that the severity of many diseases, including those caused by parasites, has been shown to be affected by one or more of these circumstances. In addition, infection with many pathogens has been shown to have an adverse influence on pregnancy. In this article we review the impact of sex-associated hormones on the immune system and the development and maintenance of immunity to the intracellular protozoan parasites Toxoplasma gondii, Plasmodium spp., and Leishmania spp.

A comparison of vascularized and nonvascularized bone grafts for reconstruction of mandibular continuity defects

PURPOSE

This study compared vascularized and nonvascularized bone grafts for the reconstruction of segmental defects of the mandible.

PATIENTS AND METHODS

The results in 39 patients having vascularized bone grafts (38 fibulas and one iliac crest) and 29 patients having nonvascularized bone grafts (26 iliac crest [22 corticocancellous block grafts, four cancellous bone grafts in a tray] and three rib grafts) for segmental mandibular reconstruction were evaluated in terms of overall success rate, total number of surgeries performed, total blood loss, total number of hospital days, and total number of hours in the operating room.

RESULTS

Of 39 vascularized bone grafts, two failed (95% success rate), whereas of 29 nonvascularized bone grafts, seven failed (76% success rate). Failure for the nonvascularized bone grafts was closely correlated to the length of the defect. Nonvascularized bone graft patients underwent an average of one more surgical procedure for total reconstruction than vascularized bone graft patients, including osseointegrated implants. However, vascularized bone graft patients spent a mean of over 14 additional days in the hospital for all of their reconstructive procedures and an additional 3 hours in the operating room as compared with nonvascularized bone graft patients. Blood loss was similar in both groups (1,100 mL). Only 20% to 24% of patients in each treatment group have completed reconstruction to include osseointegrated implants.

CONCLUSIONS

The success rate for vascularized bone grafting is high and is the treatment of choice when primary reconstruction is required, when the patient has been previously irradiated, or when simultaneous replacement of soft tissue is required. Vascularized bone grafts are also the treatment of choice for mandibular replacements over 9 cm in length. Nonvascularized bone grafts create a better contour and bone volume for facial esthetics and subsequent implant insertion, and may be the treatment of choice for secondary reconstruction of defects less than 9 cm in length.

casanova encodes a novel Sox-related protein necessary and sufficient for early endoderm formation in zebrafish

Early endoderm formation in zebrafish requires at least three loci that function downstream of Nodal signaling but upstream of the early endodermal marker sox17: bonnie and clyde (bon), faust (fau), and casanova (cas). cas mutants show the most severe phenotype as they do not form any gut tissue and lack all sox17 expression. Activation of the Nodal signaling pathway or overexpression of Bon or Fau/Gata5 fails to restore any sox17 expression in cas mutants, demonstrating that cas plays a central role in endoderm formation. Here we show that cas encodes a novel member of the Sox family of transcription factors. Initial cas expression appears in the dorsal yolk syncytial layer (YSL) in the early blastula, and is independent of Nodal signaling. In contrast, endodermal expression of cas, which begins in the late blastula, is regulated by Nodal signaling. Cas is a potent inducer of sox17 expression in wild-type embryos as well as in bon and fau/gata5 mutants. Cas is also a potent inducer of sox17 expression in MZoep mutants, which cannot respond to Nodal signaling. In addition, ectopic expression of cas in presumptive mesodermal cells leads to their transfating into endoderm. Altogether, these data indicate that Cas is the principal transcriptional effector of Nodal signaling during zebrafish endoderm formation.

A molecular pathway leading to endoderm formation in zebrafish

BACKGROUND

Several potentially important regulators of vertebrate endoderm development have been identified, including Activin-related growth factors and their receptors; transcriptional regulators encoded by the genes Mixer, Xsox17, and HNF3beta; zebrafish One-eyed pinhead (Oep), a member of the Cripto/FRL-1/Cryptic family of epidermal growth factor related proteins (EGF-CFC); and the product of the zebrafish locus casanova, which plays an essential cell-autonomous role in endoderm formation.

RESULTS

Using overexpression studies and the analysis of different zebrafish mutants, we have assembled a molecular pathway that leads to endoderm formation. We report that a zebrafish Sox17 homologue is expressed during gastrulation exclusively in the endoderm and that casanova mutants lack all sox17 expression. Overexpression of mixer induces ectopic sox17-expressing cells in wild-type embryos and promotes endoderm formation in oep mutants, but does not rescue sox17 expression or endoderm formation in casanova mutants. Overexpression of a constitutively active form of the type I transforming growth factor beta (TGF-beta) receptor TARAM-A also promotes sox17 expression in wild-type and oep mutant embryos, but not in casanova mutants. We also show that the Nodal-related molecules Cyclops and Squint and the transmembrane protein Oep are essential for normal mixer expression.

CONCLUSIONS

The data indicate that the following pathway leads to zebrafish endoderm formation: Cyclops and Squint activate receptors such as TARAM-A; Oep also appears to act upstream of such receptors; signals transduced by these receptors lead to the expression of mixer, Mixer then acts through casanova to promote the expression of sox17 and differentiation of the endoderm.

Vascular permeability factor/vascular endothelial cell growth factor-mediated permeability occurs through disorganization of endothelial junctional proteins

Vascular permeability factor/vascular endothelial growth factor stimulates endothelial proliferation, angiogenesis, and increased vascular permeability in vivo. We investigated mechanisms of vascular permeability factor-mediated endothelial monolayer permeability changes in vitro. [14C]Albumin flux across endothelial monolayers was measured following a 90-min exposure to vascular permeability factor (660 pM). Vascular permeability factor increased albumin flux to 3.4 times that of control albumin flux. Endothelial monolayers were also incubated for 90 min with vascular permeability factor plus Gö6976 (10 nM), staurosporine (1 microM), wortmannin (10 nM), AG126 (1 and 2.67 microM), and PD98059 (20 microM). Vascular permeability factor-mediated permeability was not blocked by Gö6976, an antagonist of "classical" protein kinase C, staurosporine, a pan-protein kinase C antagonist, nor wortmannin, a PI3-kinase blocker, but was blocked by incubation with AG126 or PD98059, inhibitors of mitogen-activated protein kinase activation. Immunofluorescent staining of the junctional proteins VE-cadherin and occludin showed a loss of these proteins from the endothelial junction that was prevented by co-incubation with AG126 or PD98059. These data demonstrate that vascular permeability factor increases albumin permeability across endothelial monolayers in vitro and suggests that permeability increases through rearrangement of endothelial junctional proteins involving the mitogen-activated protein kinase signal transduction pathway.

casanova plays an early and essential role in endoderm formation in zebrafish

The cellular and molecular mechanisms that regulate endoderm development in vertebrates have only recently begun to be explored. Here we show that the zebrafish locus casanova plays an early and essential role in this process. casanova mutants lack a gut tube and do not express any molecular markers of endoderm differentiation. The early endodermal expression of genes such as axial, gata5, and fkd2 does not initiate in casanova mutants, indicating that the endoderm is defective from the onset of gastrulation. Mosaic analysis demonstrates that casanova functions cell autonomously within the endodermal progenitors. We also report the isolation of a zebrafish homologue of Mixer, a gene important for early endoderm formation in Xenopus. casanova does not encode zebrafish Mixer, and mixer expression is normal in casanova mutants, indicating that casanova acts downstream of, or parallel to, mixer to promote endoderm formation. We further find that the forerunner cells, a specialized group of noninvoluting dorsal mesendodermal cells, do not form in casanova mutants. Studies of casanova mutants do not support an important role for the forerunner cells in either dorsal axis or tail development, as has been previously proposed. In addition, although different populations of mesodermal precursors are generated normally in casanova mutants, morphogenetic defects in the heart, vasculature, blood, and kidney are apparent, suggesting a possible role for the endoderm in morphogenesis of these organs.

TGF-β1-induced EMT promotes targeted migration of breast cancer cells through the lymphatic system by the activation of CCR7/CCL21-mediated chemotaxis

Tumor cells frequently disseminate through the lymphatic system during metastatic spread of breast cancer and many other types of cancer. Yet it is not clear how tumor cells make their way into the lymphatic system and how they choose between lymphatic and blood vessels for migration. Here we report that mammary tumor cells undergoing epithelial–mesenchymal transition (EMT) in response to transforming growth factor-β (TGF-β1) become activated for targeted migration through the lymphatic system, similar to dendritic cells (DCs) during inflammation. EMT cells preferentially migrated toward lymphatic vessels compared with blood vessels, both in vivo and in 3D cultures. A mechanism of this targeted migration was traced to the capacity of TGF-β1 to promote CCR7/CCL21-mediated crosstalk between tumor cells and lymphatic endothelial cells. On one hand, TGF-β1 promoted CCR7 expression in EMT cells through p38 MAP kinase-mediated activation of the JunB transcription factor. Blockade of CCR7, or treatment with a p38 MAP kinase inhibitor, reduced lymphatic dissemination of EMT cells in syngeneic mice. On the other hand, TGF-β1 promoted CCL21 expression in lymphatic endothelial cells. CCL21 acted in a paracrine fashion to mediate chemotactic migration of EMT cells toward lymphatic endothelial cells. The results identify TGF-β1-induced EMT as a mechanism, which activates tumor cells for targeted, DC-like migration through the lymphatic system. Furthermore, it suggests that p38 MAP kinase inhibition may be a useful strategy to inhibit EMT and lymphogenic spread of tumor cells.

Randomised controlled trial of psychological debriefing for victims of acute burn trauma

BACKGROUND

Psychological debriefing (PD) is widely used following major traumatic events in an attempt to reduce psychological sequelae.

METHOD

One hundred and thirty-three adult burn trauma victims entered the study. After initial questionnaire completion, participants were randomly allocated to an individual/couple PD group or a control group who received no intervention; 110 (83%) were interviewed by an assessor blind to PD status three and 13 months later.

RESULTS

Sixteen (26%) of the PD group had PTSD at 13-month follow-up, compared with four (9%) of the control group. The PD group had higher initial questionnaire scores and more severe dimensions of burn trauma than the control group, both of which were associated with a poorer outcome.

CONCLUSION

This study seriously questions the wisdom of advocating one-off interventions post-trauma, and should stimulate research into more effective initiatives.

Deep venous thrombosis: US assessment using vein compression

To assess vein compressibility as a simple ultrasound (US) technique to determine the presence of venous thrombi, 51 patients undergoing contrast material venography of the lower extremity because of a clinical suspicion of deep venous thrombosis (DVT) also underwent high-resolution US evaluation of the veins. DVT was diagnosed on 28 venograms. In 25 patients US studies demonstrated non-compressibility of the veins, indicating the presence of clot. In 23 patients with normal venograms, US examinations demonstrated total compressibility of the veins, indicating the absence of DVT. Clots below the knee were not depicted by US. In this study US had a sensitivity of 89% and a specificity of 100%.

Leishmania species: models of intracellular parasitism

Leishmania species are obligate intracellular parasites of cells of the macrophage-dendritic cell lineage. Indeed, the ability to survive and multiply within macrophages is a feature of a surprising number of infectious agents of major importance to public health, including Mycobacterium tuberculosis, Mycobacterium leprae, Listeria monocytogenes, Salmonella typhimurium, Toxoplasma gondii and Trypanosoma cruzi. The relationship between such organisms and their host cells is particularly intriguing because, not only are macrophages capable of potent microbicidal activity, but in their antigen-presenting capacity they can orchestrate the developing immune response. Thus, to initiate a successful infection parasites must gain entry into macrophages, and also withstand or circumvent their killing and degradative functions. However, to sustain a chronic infection, parasites must also subvert macrophage-accessory-cell activities and ablate the development of protective immunity. The leishmanias produce a wide spectrum of disease in mice, and as such they have provided excellent models for studying problems associated with intracellular parasitism. In recent years, largely using these organisms, we have made enormous progress in elucidating the mechanisms by which successful intracellular infection occurs. Furthermore, characterization of immunological pathways that are responsible for resistance or susceptibility to Leishmania has given rise to the Th1/Th2 paradigm of cellular/humoral dominance of the immune response.

Fusion of host cell secondary lysosomes with the parasitophorous vacuoles of Leishmania mexicana-infected macrophages

Secondary lysosomes of cultured mouse peritoneal macrophages were labeled with the electron-dense colloid saccharated iron oxide; the identity of the labeled structures was checked by the Gomori reaction for acid phosphatase. Amastigotes of Leishmania mexicana mexicana derived from mouse lesions were used to infect these macrophages in vitro. In electron micrographs of thin sections of infected macrophages the labeled secondary lysosomes were seen fused with the parasitophorous vacuoles without preventing subsequent multiplication of the parasites. A similar fusion probably occurs in vivo, and may provide a pathway through which not only nutrients but also drugs and host antibodies could reach the intracellular parasite.

Tissue distribution and clearance kinetics of non-transferrin-bound iron in the hypotransferrinemic mouse: a rodent model for hemochromatosis

Genetically hypotransferrinemic mice accumulate iron in the liver and pancreas. A similar pattern of tissue iron accumulation occurs in humans with hereditary hemochromatosis. In both disorders, there is a decreased plasma concentration of apotransferrin. To test the hypothesis that nontransferrin-bound iron exists and is cleared by the parenchymal tissues, the tissue distribution of 59Fe was studied in animals lacking apotransferrin. Two groups of animals were used: normal rats and mice whose transferrin had been saturated by an intravenous injection of nonradiolabeled iron, and mice with congenital hypotransferrinemia. In control animals, injected 59Fe was found primarily in the bone marrow and spleen. In the transferrin iron-saturated animals, injected 59Fe accumulated in the liver and pancreas. Gastrointestinally absorbed iron in hypotransferrinemic or transferrin iron-saturated mice was deposited in the liver. This indicates that newly absorbed iron is released from mucosal cells not bound to transferrin. Clearance studies demonstrated that transferrin-bound 59Fe was removed from the circulation of rats with a half-time of 50 min. In transferrin iron-saturated animals, injected 59Fe was removed with a half-time of less than 30 s. Analysis of the distribution of 59Fe in serum samples by polyacrylamide gel electrophoresis demonstrated the presence of 59Fe not bound to transferrin. These results demonstrate the existence of and an uptake system for non-transferrin-bound iron. These observations support the hypothesis that parenchymal iron overload is a consequence of reduced concentrations of apotransferrin.

H(2)O(2)-mediated permeability: role of MAPK and occludin

H(2)O(2)-mediated elevation in endothelial solute permeability is associated with pathological events such as ischemia-reperfusion and inflammation. To understand how H(2)O(2) mediates increased permeability, we investigated the effects of H(2)O(2) administration on vascular endothelial barrier properties and tight junction organization and function. We report that H(2)O(2) exposure caused an increase in endothelial solute permeability in a time-dependent manner through extracellularly regulated kinase 1 and 2 (ERK1/ERK2) signal pathways. H(2)O(2) exposure caused the tight junctional protein occludin to be rearranged from endothelial cell-cell junctions. Occludin rearrangement involved redistribution of occludin on the cell surface and dissociation of occludin from ZO-1. Occludin also was heavily phosphorylated on serine residues upon H(2)O(2) administration. H(2)O(2) mediates changes in ERK1/ERK2 phosphorylation, increases endothelial solute permeability, and alters occludin localization and phosphorylation were all blocked by PD-98059, a specific mitogen-activated protein (MAP) or ERK kinase 1 inhibitor. These data strongly suggest that H(2)O(2)-mediated increased endothelial solute permeability involves the loss of endothelial tight junction integrity through increased ERK1/ERK2 activation.

Reversal of natural killing susceptibility in target cells expressing transfected class I HLA genes

A number of studies have suggested that resistance of target cells to natural killing (NK) may be correlated with their level of expression of major histocompatibility complex (MHC) class I antigens. To examine this hypothesis directly, a NK-sensitive class I-deficient human B-cell line was transfected with MHC class I genes. The expression of transfected HLA, but not H-2, class I gene products resulted in loss of susceptibility to human NK-mediated conjugation and cytolysis. Furthermore, this protection did not extend to cytotoxicity mediated by interleukin 2-stimulated human NK effector cells.