Epidemiological, clinical, and neuropathological study of apolipoprotein E genotype in Alzheimer's disease

Our studies of the APOE genotype in AD confirm a strong association of the epsilon 4 allele with development of AD and a decreased risk associated with epsilon 2. From a clinical/neuropathological perspective, the major effects of APOE epsilon 4 are to lower the age of onset and to increase the amount of A beta deposit in the brain. Neither rate of progression nor number of neurofibrillary tangles were affected. We also carried out a longitudinal population-based assessment of the APOE genotype to determine the risk for developing cognitive impairment of someone in the general population based on APOE genotype. APOE epsilon 4 carried about 1.4-fold increased risk, and APOE epsilon 2 about 1.7-fold decreased risk. Thus, inheritance of APOE epsilon 4 is a major biological risk factor for AD, but it has limited utility as a prognostic indicator for development of dementia in an individual.

Natural beta-carotene and whole body irradiation in rats

beta-carotene and other carotenoids are reported to be potent free radical quenchers, singlet oxygen scavengers, and lipid antioxidants. Whole-body irradiation is known to cause an immunosuppression effect in mammals through the possible initiation and production of reactive oxygen species. We decided to test the possible antioxidative effect against whole-body irradiation of a natural beta-carotene, composed of equal amounts of the all-trans and 9-cis isomers, obtained from the unicellular alga Dunaliella bardawil. Rats were fed on ground commercial food enriched with natural beta-carotene (50 mg/kg diet). On completion of 1 week with beta-carotene, the rats were exposed to a single dose of 4 Gy whole-body irradiation, after which their livers and blood were removed for beta-carotene and retinol analysis in comparison with control livers of animals irradiated or not, or supplemented with beta-carotene after irradiation. A normal increase in body weight with no ill effects was noted in the groups of rats whose diet was supplemented by beta-carotene before and after irradiation, compared with the reduction in the specific growth rate in the group of rats irradiated without beta-carotene. Liver beta-carotene and retinol decreased significantly after irradiation compared with the rats which were not irradiated. This decrease was not shown in rats fed beta-carotene prior to irradiation, and the effect of irradiation was partially cured by supplementation with beta-carotene after irradiation. High-pressure liquid chromatography (HPLC) analysis of the irradiated animals showed a selective decline in 9-cis beta-carotene and in retinol over all-trans beta-carotene and retinyl-esters. These results suggest that 9-cis beta-carotene and retinol protect in vivo against the cellular damage by free radicals induced after whole-body irradiation.

Hemodynamic effects of peritoneovenous shunts in hemodialysis patients with ascites

Ascites in hemodialysis patients has been reported in association with systemic diseases, such as cirrhosis or congestive heart failure, and as an idiopathic form. Regardless of the etiology, these patients often are refractory to treatment with intradialytic ultrafiltration because of recurrent hypotensive episodes. In this report we describe the hemodynamic effects of peritoneovenous shunts (PVSs) in three hemodialysis patients with ascites refractory to conventional treatment. One patient had idiopathic ascites and the other two had associated liver disease. Patients were monitored for lowest blood pressure, number of intradialytic hypotensive episodes, number of grams of albumin infused to treat hypotensive episodes, interdialytic weight gain, and hemodynamic stability (defined as the difference between the predialysis mean arterial pressure and the lowest intradialytic mean arterial pressure). In all three patients the hemodynamic parameters stabilized after PVS placement despite equal or greater ultrafiltration during dialysis (due to a significant increase in the lowest measured intradialytic blood pressure). The total number of hypotensive episodes decreased from 219 prior to PVS placement to zero after shunt placement. The need for albumin infusion during hemodialysis (for blood pressure support) decreased (significantly in two patients), as did the volume of ascites in all three patients. One patient required PVS replacement secondary to infection, which was the only complication. We believe that refractory ascites in end-stage renal disease patients can be successfully treated by placement of a PVS, which often results in relief of the ascites and significant improvement in intradialytic hemodynamic stability.

Neural-network classifiers for automatic real-world aerial image recognition

We describe the application of the multilayer perceptron (MLP) network and a version of the adaptive resonance theory version 2-A (ART 2-A) network to the problem of automatic aerial image recognition (AAIR). The classification of aerial images, independent of their positions and orientations, is required for automatic tracking and target recognition. Invariance is achieved by the use of different invariant feature spaces in combination with supervised and unsupervised neural networks. The performance of neural-network-based classifiers in conjunction with several types of invariant AAIR global features, such as the Fourier-transform space, Zernike moments, central moments, and polar transforms, are examined. The advantages of this approach are discussed. The performance of the MLP network is compared with that of a classical correlator. The MLP neural-network correlator outperformed the binary phase-only filter (BPOF) correlator. It was found that the ART 2-A distinguished itself with its speed and its low number of required training vectors. However, only the MLP classifier was able to deal with a combination of shift and rotation geometric distortions.

Twenty-four-hour ambulatory electrocardiography in elderly subjects: prevalence of various arrhythmias and prognostic implications (report from the Bronx Longitudinal Aging Study)

Functional, ambulatory, community-dwelling subjects (n = 423, aged 75 to 85 years) underwent baseline 24-hour ambulatory electrocardiography (ECG) examinations as part of the Bronx Aging Study, a 10-year prospective cohort study designed to identify risk factors and disease markers for cardiovascular, cerebrovascular, and dementia illnesses in old people. Premature ventricular contractions were the most commonly observed arrhythmia noted (93% of subjects), with a low prevalence of nonsustained ventricular tachycardia (5%), paroxysmal atrial tachycardia (13%), atrial fibrillation (4%), and atrioventricular blocks (4%). A 24-hour sinus rate of < 60 beats/min was noted in 13% of subjects, and 11% of subjects were noted to have transient episodes of severe bradycardia (< 40 beats/min). In a multivariate analysis, nonsustained ventricular tachycardia was an independent predictor of death (p = 0.015; relative risk [RR] 2.8; 95% confidence interval [CI] 1.4 to 5.8) and myocardial infarction (p = 0.031; RR 3.2; CI 1.2 to 9.4). Transient atrioventricular block was an independent predictor of stroke (p - 0.0006; RR 9.7; CI 3.3 to 28.9), as was sinus bradycardia over a 24-hour period (p = 0.033; RR 2.7; CI 1.2 to 6.4). Ventricular tachycardia approached significance as an independent predictor of multiinfarct dementia (p = 0.052; RR 6.3; CI 1.4 to 28.7). Episodes of paroxysmal atrial fibrillation, a trial tachycardia, and severe bradycardia were not associated with adverse outcomes. Some arrhythmias found on the ambulatory ECG in very old subjects can predict an increased risk for subsequent death, myocardial infarction, stroke, and multiinfarct dementia.

Syk tyrosine kinase is required for immunoreceptor tyrosine activation motif-dependent actin assembly

Clustering of several multisubunit receptors on hematopoetic cells results in a signaling cascade involving the phosphorylation of immunoreceptor tyrosine activation motifs, or "ITAMs," and actin polymerization. Recent experiments indicate that direct clustering of the ITAM-binding protein, p72(syk) (Syk), is capable of transmitting a phagocytic signal in COS cells (Greenberg, S., Chang, P., Wang, D., Xavier, R., and Seed, B.(1996) Proc. Natl. Acad. Sci. U. S. A. 93, 1103-1107). However, the possibility of redundant signaling pathways makes it difficult to test the requirement for Syk in ITAM-dependent actin polymerization in hematopoetic cells. We developed a model system to study ITAM-dependent actin assembly. DT40 lymphocytes were transfected with fusion proteins encoding the transmembrane and cytosolic domains of the ITAM-containing gamma subunit of Fc receptors. Clustering the gamma-containing fusion proteins with IgG-coated erythrocytes triggered submembranous actin assembly. This response depended on an intact ITAM, was absent in cell lines that had been engineered to lack Syk, and was augmented in cell lines that stably overexpressed Syk. These experiments demonstrate an absolute requirement for Syk tyrosine kinase in ITAM-dependent actin assembly in transfected lymphocytes.

Lack of association of trinucleotide repeat polymorphisms in very-low-density lipoprotein receptor gene with Alzheimer's disease

Inheritance of the apolipoprotein E epsilon 4 allele is a risk factor for Alzheimer's disease (AD). A recent report studying Japanese patients suggested that a polymorphism of a trinucleotide repeat in the 5' untranslated region of an apolipoprotein E receptor, the very-low-density lipoprotein receptor, is genetically associated with AD, with overrepresentation of the allele containing five copies of the repeat. We determined the allele frequencies of the very-low-density lipoprotein receptor in 3 white populations totaling 469 individuals. In contrast to the previous report, we found no differences in allele frequencies between case patients and control subjects. The discrepancy could be due to differences in Japanese and white populations. Nonetheless, these data weaken the likelihood that this polymorphism in the very-low-density lipoprotein receptor gene is strongly associated with AD.

Clustered syk tyrosine kinase domains trigger phagocytosis

Phagocytosis is a phylogenetically primitive mechanism adapted by specialized cells of the immune system to ingest particulate pathogens. Recent evidence suggests that the program of specific cytoskeletal rearrangements that underlies phagocytosis may share elements with the antigen receptor signaling pathway in lymphocytes. Tyrosine phosphorylation, necessary for both lymphocyte effector function and phagocytosis, is thought to allow cytoskeletal elements to couple to the intracellular domains of antigen and Fc receptor subunits. We show here that the intracellular domains of the receptors are not inherently required for cytoskeletal coupling. Chimeric transmembrane proteins bearing syk but not src family tyrosine kinase domains are capable of autonomously triggering phagocytosis and redistribution of filamentous actin in COS cells. These responses cannot be initiated by a receptor chimera bearing a point mutation in the syk catalytic domain, and the kinase domain alone is sufficient for initiating cytoskeletal coupling.

Cellular signaling pathways and cytoskeletal organization

We describe a possible mechanism by which the amyloid precursor protein (APP) may be linked to the intraneuronal pathology of Alzheimer's disease (AD). Extracellular proteolytic products of APP may directly or indirectly transduce signals to cells under normal as well as pathological conditions. This activity appears to reside in the cysteine-rich amino terminus of APP. How APP or its metabolic products may affect the phosphorylation of tau is considered.

Leukemic phase of mantle cell lymphoma two case reports and review of the literature

Two cases of mantle cell lymphoma are presented. Both patients were women, aged 68 and 56 years, who presented with lymph node enlargement. Each case was initially interpreted as a follicular small cleaved cell lymphoma. Both patients later presented with splenomegaly and recurrent lymphadenopathy. Morphologic and immunologic studies on a parotid swelling in one case and a splenectomy specimen in the other indicated a diagnosis of mantle cell lymphoma. Both women subsequently presented in leukemic phase associated with a poor prognosis, and both patients succumbed soon after. The characteristics, differential diagnosis, and leukemic phase of mantle cell lymphoma are discussed. The importance of appropriate immunohistochemical and flow cytometry analysis in distinguishing mantle cell lymphoma from morphologically similar follicular center cell lymphomas is demonstrated.

Implantable cardioverter defibrillator: use in patients with no symptoms and at high risk

Twenty-seven patients with asymptomatic, nonsustained ventricular tachycardia whose evaluation suggested they were at high risk for sustained ventricular arrhythmias were treated with implantable cardioverter defibrillators. The option of conventional therapy (including the option of no therapy) was presented to each patient and rejected in favor of defibrillator implantation on an experimental basis. Eighteen patients had coronary artery disease and inducible sustained ventricular tachycardia, 8 had idiopathic dilated cardiomyopathy, and 1 had hypertrophic cardiomyopathy and a strong family history of sudden cardiac death. The mean ejection fraction was 27% +/- 10%. Operative morbidity (3%) and mortality (3%) were low. Mean overall survival was 92% and 88% at 1 and 2 years, respectively. Sixteen (59%) of the 27 patients had appropriate defibrillator discharges during a mean follow-up of 35 +/- 15 months. The mean time to first appropriate discharge was 18 +/- 17 months, and mean follow-up after first discharge was 17 +/- 20 months. In conclusion, implantable cardioverter defibrillator placement in high-risk patients without symptoms is a feasible approach that may have resulted in benefit in selected patients. Large-scale randomized trials currently under way will determine the risk/benefit ratio of this management approach.

Mesna, doxorubicin, ifosfamide, and dacarbazine chemotherapy for ovarian mixed müllerian sarcoma: report of four cases

Four patients with metastatic ovarian mixed Müllerian sarcoma (2 homologous, 2 heterologous) were treated with mesna, doxorubicin, ifosfamide, and dacarbazine (MAID) chemotherapy. Two of four patients had optimal debulking. Three of four patients responded to chemotherapy, with two complete responses of 34- and 46-month duration. The MAID regimen appears to be active in patients with ovarian sarcoma.

Unsuspected primary cervical lymphoma presenting as "cervical fibroid": partial response to leuprolide acetate

An unsuspected primary cervical lymphoma thought to be a cervical fibroid decreased in size dramatically after initiation of Leuprolide acetate prior to being correctly diagnosed during subsequent hysterectomy for uterine bleeding. This case represents the first reported successful use of Leuprolide acetate against a reticuloendothelial tumor.

Treatment of Hassidic Jewish patients in a general hospital medical-psychiatric unit

A combined medical-psychiatric inpatient unit at a general medical center in Brooklyn, New York, provides inpatient psychiatric treatment to members of the Orthodox Jewish sect of the Lubavitcher Hassidim, who are generally reluctant to accept treatment in traditional psychiatric inpatient settings. The unit's biological treatment model, which emphasizes long-term maintenance on psychotropic medication, monthly postdischarge pharmacotherapeutic visits, lowered expectations, and minimal use of expressive psychotherapy, is compatible with the Hassidic community's view of mental illness. A practicing Orthodox Jewish psychiatrist on the unit staff sensitizes other staff members to religious and cultural issues in treating Hassidic patients.

Soluble ligands of the alpha v beta 3 integrin mediate enhanced tyrosine phosphorylation of multiple proteins in adherent bovine pulmonary artery endothelial cells

Binding of substrate-bound extracellular matrix proteins to cell surface integrins results in a variety of cellular responses including adhesion, cytoskeletal reorganization, and gene expression. We have previously shown that addition of soluble SC5b-9, the complement-vitronectin complex, resulted in an RGD-dependent increase in lung venular hydraulic conductivity (Ishikawa, S., Tsukada, H., and Bhattacharya, J. (1993) J. Clin. Invest. 91, 103-109). To identify specific integrin(s) and signal transduction pathways that are responsive to soluble vitronectin-containing ligands, we exposed confluent bovine pulmonary artery cells to purified soluble human mono- or multimeric vitronectin, or SC5b-9, and determined the extent of endothelial cell protein tyrosine phosphorylation. Monomeric vitronectin (Vn) did not induce enhanced protein tyrosine phosphorylation. However, multimeric Vn and SC5b-9 elicited time- and concentration-dependent increases in tyrosine phosphorylation of numerous proteins. Antiserum against vitronectin, RGD peptides, and monoclonal and polyclonal antibodies against the alpha v beta 3 integrin blocked the vitronectin- or SC5b-9-induced enhanced accumulation of tyrosine phosphoproteins, while antibodies against beta 1 integrins and the alpha v beta 5 integrin did not. Clustering of the alpha v beta 3 integrin using monoclonal antibody LM609 caused a pattern of enhanced tyrosine phosphorylation similar to that caused by multimeric Vn and SC5b-9, suggesting that aggregation of alpha v beta 3 was critical for signaling. Among the proteins that underwent enhanced tyrosine phosphorylation in response to vitronectin were the cytoskeletal proteins paxillin, cortactin, and ezrin, as well as the SH2 domain-containing protein Shc, and p125FAK. We conclude that ligation of the alpha v beta 3 integrin by soluble ligands promotes enhanced phosphorylation of several proteins implicated in tyrosine kinase signaling and suggest that this pathway may be important in inflammatory states which are accompanied by accumulation of SC5b-9.

Phosphorothioate oligonucleotides bind in a non sequence-specific manner to the nucleolar protein C23/nucleolin

To design optimal strategies for intracellular delivery of antisense phosphorothioate oligonucleotides, it may be useful to understand their interaction with cellular macromolecules. Nuclear extracts from LOX amelanotic myeloma cells were studied for protein binding to phosphorothioate oligonucleotides using a Southwestern protocol. Multiple nuclear proteins bound to the phosphorothioate oligonucleotides but no detectable protein binding was found to phosphodiester oligonucleotides. The protein with the strongest binding signals was shown by immunoprecipitation to be nucleolar C23/nucleolin, a 110 kDa protein. With glutathione S-transferase/nucleolin fusion protein constructs, the region of nucleolin containing the RNA recognition motifs had binding activity to phosphorothioate oligonucleotides.

Differential effects of in vivo ethanol on LPS-induced TNF and nitric oxide production in the lung

Alcohol (EtOH) has been shown to suppress lipopolysaccharide (LPS)-induced nitric oxide (NO) generation and tumor necrosis factor (TNF) production in the lung in vivo. We have previously reported that EtOH suppressed gene expression for inducible nitric oxide synthase (iNOS) with a subsequent decrease in release of reactive nitrogen intermediates by alveolar macrophages and recruited lung neutrophils. We hypothesized that a similar mechanism may be involved in EtOH-induced suppression of LPS-stimulated TNF production. In contrast to what we found with iNOS, EtOH had no effect on TNF mRNA in alveolar macrophages or recruited lung neutrophils. However, immunoreactive and bioactive TNF was reduced by 72%. EtOH treatment resulted in an increased level of the membrane-bound 26-kDa form of TNF, which suggested that proteolytic cleavage of this prohormone was affected by EtOH. Experiments with t-butyl alcohol, a tertiary alcohol that is not metabolized to acetaldehyde, yielded similar results. Thus EtOH appears to be the active substance in suppression of TNF in the lung in vivo. Pretreatment with intratracheal interferon-gamma 24 h before intratracheal LPS increased TNF bioactivity partly due to increased TNF mRNA and by increasing TNF processing, as evidenced by a decrease in the 26-kDa TNF prohormone and an increase in immunoreactive and bioactive TNF.

Acute interstitial nephritis associated with ticlopidine

Ticlopidine, a platelet aggregation inhibitor, has been approved to decrease the risk of thrombotic stroke. We describe a 75-year-old white woman who developed acute renal failure 10 days after initiating ticlopidine therapy. A renal biopsy revealed interstitial infiltrates containing lymphocytes and eosinophils. To our knowledge this is the first report of ticlopidine-induced acute interstitial nephritis.

Reframing dependence in old age: a positive transition for families

This article re-evaluates the role of dependence in late-life development using concepts drawn from psychology, sociology, social work, gerontology, and scholarship on women's development. A perspective of old age as a time of continued, positive growth and change is proposed. Dependence is not a marker of decline and deterioration, but a necessary development for mutual growth and enhancement of late-life family reciprocity. Accepting dependence helps an older person maintain his or her competence, autonomy, and self-esteem. The process of dependence as growth promoting is discussed and illustrated with case examples.

Ethanol suppresses Mycobacteria tuberculosis-induced mRNA for nitric oxide synthase in alveolar macrophages, in vivo

Acute ingestion of alcohol [ethanol (ETOH)] adversely affects the immunocompetence of both naive individuals as well as chronic alcohol abusers. An increased incidence and severity of tuberculosis is found in chronic alcohol abusers. Nitric oxide (NO) produced by alveolar macrophages (AMs) may play a role in the in vitro killing of Mycobacterium avium and Mycobacterium tuberculosis (MTB). Moreover, tumor necrosis factor-alpha (TNF-alpha) is believed to be a primary cytokine mediator of NO production by AMs. Recent studies from our laboratory demonstrated that ETOH suppressed endotoxin-induced increases in both TNF-alpha and NO in AMs, in vivo. We tested the postulate that acute ingestion of ETOH can interfere with mycobacteria-induced upregulation of the NO system in AMs, in vivo. We show that heat-killed M. avium complex (MAC) and human virulent MTB instilled into rat lungs rapidly increased mRNA for inducible NO synthase II (iNOS) of AMs in fluid obtained by bronchoalveolar lavage (BAL fluid). This was associated with production of reactive nitrogen intermediates [(RNIs); NO2- and NO3-] in BAL fluid, lung homogenate, and AMs in the absence of a significant increase in BAL fluid TNF-alpha. A single dose of ETOH (5.5 g/kg, ip) administered 30 min before intratracheal administration of MAC or MTB attenuated both MAC and MTB-induced increases in RNI in BAL fluid, lung, and AMs, and the increase in mRNA for iNOS. Thus, mycobacteria upregulate iNOS mRNA and enhance RNI production by AMs without any increase in the production of TNF-alpha. Moreover, ETOH attenuates mycobacteria-induced upregulation of mRNA for iNOS and RNI production in the absence of ETOH-mediated suppression of TNF. Speculatively, ETOH-mediated inhibition of the AM NO system may offer an explanation for the increased severity of mycobacterial infections in alcoholics.

Adenovirus-mediated blockade of tumor necrosis factor in mice protects against endotoxic shock yet impairs pulmonary host defense

A replication-deficient recombinant adenovirus encoding a chimeric protein capable of binding tumor necrosis factor (TNF) and lymphotoxin was given to mice. Administration of this virus (10(9) pfu intravenously) yielded high levels of the recombinant protein in plasma and afforded significant protection to a lethal challenge with lipopolysaccharide with or without D-galactosamine. However, this protein inhibitor was readily detectable in the lung and was associated with decreased neutrophil recruitment and bacterial killing after intratracheal LPS or Pseudomonas aeruginosa, respectively. These data reflect the dual role of many proinflammatory cytokines. This model of TNF inhibition is similar to the homozygous 55-kDa TNF receptor deletion; thus, adenovirus-mediated gene transfer of cytokine inhibitors in vivo is a useful tool to abrogate the function of single or multiple cytokines for investigational or therapeutic purposes.

Relationship between sodium balance and renal innervation during hypertension development in the spontaneously hypertensive rat

INTRODUCTION

The spontaneously hypertensive rat (SHR) has been shown to possess elevated efferent sympathetic nerve activity, and renal denervation delays the development of hypertension in this genetic strain. Evidence that the renal sympathetic nerves have direct effects on tubular function suggests that one of the mechanisms for increasing arterial pressure in the SHR might involve neurally mediated sodium retention.

AIMS AND METHODS

The present study examined the relationships between renal sympathetic tone, daily sodium balance and the development of hypertension in SHR over a 4-week period. Conscious, unrestrained, 7-week-old SHR with innervated or denervated kidneys were placed on a fixed sodium intake by intravenous infusion (5.72 mumol/day per 100 g body weight). Urinary sodium excretion was determined once a day for 28 consecutive days; systolic blood pressure (SBP) and body weight were monitored twice a week.

RESULTS

Renal denervation delayed the onset of and retarded the development of hypertension. Despite the difference in SBP, daily sodium balance was equal in the innervated and the denervated SHR. The positive sodium balances exhibited by both groups are attributed to the rapid growth observed during the time course of the experiment. The growth rate was also similar in the two groups.

CONCLUSION

The present data indicate that, although the renal nerves may mediate enhanced transient tubular sodium reabsorption, sodium retention does not contribute directly to the development of hypertension in the SHR. Rather, it appears that the elevation of arterial pressure might occur as a requirement to excrete excess sodium and thus maintain a daily sodium balance.

P2Z adenosine triphosphate receptor activity in cultured human monocyte-derived macrophages

The present study shows that human mononuclear phagocytes express a P2Z-like purinergic membrane receptor activity. Extracellular adenosine triphosphate (ATP) induces the formation of nonselective membrane pores in human mononuclear phagocytes that allow the entry of otherwise membrane impermeant fluorescent dyes (YO-PRO-1 or Lucifer yellow) into the cytoplasm of these cells. The percentage of mononuclear phagocytes that was permeabilized by ATP increased as monocytes matured into macrophages. Their response to ATP was inhibited by Mg2+ and oxidized ATP. Benzoylbenzoic-ATP (BzBzATP) was approximately 60% as effective as ATP and adenosine-5 -O-(thiophosphate) (ATP gamma S) was less than 20% as effective as ATP in permeabilizing human macrophages to YO-PRO-1 or Lucifer Yellow. Thus, the human P2Z-like receptor differs from its murine counterpart because BzBzATP, ATP, and ATP gamma S are equally efficacious in permeabilizing murine macrophage-like J774 cells to these dyes. UTP, GTP, and CTP were ineffective in permeabilizing human or murine macrophages to YO-PRO-1. Taken together, these data indicate that human monocyte-derived macrophages express a P2Z-like activity that is pharmacologically distinct from that expressed by their murine counterparts and that expression of these receptors is developmentally regulated in human mononuclear phagocytes.

Characterization of a novel tumor-derived cytokine. Endothelial-monocyte activating polypeptide II

Endothelial-monocyte activating polypeptide II (EMAP II) was initially identified in the supernatant of murine methylcholanthrene A-induced fibrosarcomas (Meth A) by its capacity to activate host effector cells (Kao, J., Ryan, J., Brett, J., Chen, J., Shen, H., Fan, Y-G., Godman, G., Familletti, P., Wang, F., Pan, Y-C., Stern, D., and Clauss, M. (1992) J. Biol. Chem. 267, 20239-20247). Based on the NH2-terminal protein sequence, a full-length cDNA has been cloned which indicates that the precursor of EMAP II is a unique, leaderless, single polypeptide chain with predicted molecular mass approximately 34 kDa and that the mature form released by Meth A cells corresponds to approximately 20 kDa. Purified recombinant mature EMAP II (EMAP II, approximately 20 kDa form) activated endothelial cells with resulting elevation of cytosolic free calcium concentration, release of von Willebrand factor, induction of tissue factor, and expression of the adhesion molecules E-selectin and P-selectin. Neutrophils exposed to EMAP II demonstrated elevated cytosolic free calcium concentration, peroxidase generation, and chemotaxis. EMAP II also activated mononuclear phagocytes elevating cytosolic free calcium concentration, inducing tumor necrosis factor-alpha (TNF) and tissue factor, and stimulating chemotaxis. Systemic infusion of EMAP II into C3H/HeJ or Balb/c mice was associated with systemic toxicity, pulmonary congestion, and the appearance of TNF, interleukin-1 and -6 in the plasma. A single intra-tumor injection of EMAP II into Meth A sarcomas induced acute thrombohemorrhage and partial tumor regression. Local injection of EMAP II into a tumor resistant to the effects of TNF, murine mammary carcinoma, rendered it sensitive to subsequently administered TNF, which resulted in acute thrombohemorrhage and partial regression. These data suggest that recombinant EMAP II, a tumor-derived cytokine, has properties of a proinflammatory mediator with the capacity to prime the tumor vasculature for a locally destructive process.