Telehealth Treatment for Opioid Use Disorder During Pregnancy

This cohort study evaluates opioid use disorder (OUD) treatment and pregnancy outcomes among pregnant patients receiving OUD care through a multistate telemedicine program in the US.

Retention in Telehealth Treatment for Opioid Use Disorder Among Rural Populations: A Retrospective Cohort Study

Introduction: There are limited studies to date on telemedicine treatment outcomes for opioid use disorder (OUD) among rural populations. Methods: This was a retrospective cohort study of rural adults enrolled in telemedicine OUD treatment. Study outcomes were percent retained in care and adherence to buprenorphine assessed by urine drug screens at 1, 3, and 6 months. Results: From April 1, 2020, through January 31, 2022, 1,816 rural patients across 14 states attended an initial telemedicine visit and received a clinical diagnosis of OUD. Participants had the following characteristics: mean age 37.7 years (±8.6); 52.4% female; and 66.7% Medicaid. At 1, 3, and 6 months, 74.8%, 61.5%, and 52.3% of participants were retained in care, and 69.0%, 56.0%, and 49.2% of participants were adherent, respectively. Conclusions: Telemedicine is an effective approach for treating OUD in rural populations, with retention comparable to in-person treatment.

Anti-N-Methyl-D-Aspartate Receptor Encephalitis: A Review of Psychiatric Phenotypes and Management Considerations: A Report of the American Neuropsychiatric Association Committee on Research

OBJECTIVE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder characterized by prominent neuropsychiatric symptoms. Given the nature of its pathophysiology, psychiatrists tend to be one of the first clinicians encountering patients with the disease.

METHODS

In the present review of patients described in the literature with psychiatric symptoms, the authors aimed to characterize the psychiatric symptoms of the disease and its management in adults and adolescents as well as children (≤12 years old). A total of 544 patients fulfilled the inclusion criteria.

RESULTS

The authors found that 77% of patients with NMDAR encephalitis presented initially with psychiatric symptoms. These were mostly agitation (59%) and psychotic symptoms (in 54%, especially disorganized behavior and visual-auditory hallucinations), with agitation even more commonly being the presenting symptom in children (66%). Where psychotic symptoms were detailed, visual (64%) and auditory (59%) hallucinations were the most common, as well as persecutory delusions (73%). However, delusions were not clearly characterized in most cases. Catatonia was described in 42% of adult patients and 35% of children. Of the patients with documented exposure to antipsychotics, 33% were suspected to have an adverse drug reaction (notably, neuroleptic malignant syndrome in 22% of the cases).

CONCLUSIONS

On the basis of these findings, it is important to consider anti-NMDAR encephalitis in the differential diagnosis of patients with an acute onset psychosis, especially in association with agitation, catatonia, or adverse response to antipsychotics. Furthermore, it is important to use antipsychotics with caution in patients with suspected or confirmed anti-NMDAR encephalitis.

Therapeutic Uses of Seizures in Neuropsychiatry

Although seizures typically indicate a state of brain dysfunction, there are circumstances in which the biological effects of a seizure may exert therapeutic benefits. The standard technique for inducing controlled therapeutic seizures in humans is electroconvulsive therapy (ECT), a treatment that involves the application of an electrical stimulus to the scalp of a patient under general anesthesia and muscle relaxation. This review discusses the contemporary use of ECT for treating certain mental and neurologic disorders and previews two experimental forms of seizure therapy that are related to ECT and may hold promise for the future: focal electrically administered seizure therapy and magnetic seizure therapy.

The emerging story of emerging technologies in neuropsychiatry

The growth of new technologies in health care is exponential, and the impact of such rapid technological innovation on health care delivery is substantial. This review describes two emerging technologies—mobile applications and wearable technologies—and uses a virtual case report to illustrate the impact of currently available technologies on the health care experience of a patient with neuropsychiatric illness.

Suspected Delirium Predicts the Thoroughness of Catatonia Evaluation

Although commonly linked to psychiatric disorders, catatonia is frequently identified secondary to neurological and general medical conditions (GMCs). The present study aimed to characterize the diagnostic workup of cases of catatonia in a general hospital setting. The authors performed a retrospective chart review of 54 cases of catatonia, over 3 years. Clinical suspicion of comorbid delirium was the strongest predictor of a more thorough general medical workup. Attribution of catatonia to a psychiatric etiology was associated with significantly less diagnostic workup. Prospective studies should help clarify the relationship between catatonia and delirium and standardize the diagnostic approach to patients presenting with catatonia.

Health care contacts in the year before suicide death

BACKGROUND

Suicide prevention is a public health priority, but no data on the health care individuals receive prior to death are available from large representative United States population samples.

OBJECTIVE

To investigate variation in the types and timing of health services received in the year prior to suicide, and determine whether a mental health condition was diagnosed.

DESIGN

Longitudinal study from 2000 to 2010 within eight Mental Health Research Network health care systems serving eight states.

PARTICIPANTS

In all, 5,894 individuals who died by suicide, and were health plan members in the year before death.

MAIN MEASURES

Health system contacts in the year before death. Medical record, insurance claim, and mortality records were linked via the Virtual Data Warehouse, a federated data system at each site.

KEY RESULTS

Nearly all individuals received health care in the year prior to death (83 %), but half did not have a mental health diagnosis. Only 24 % had a mental health diagnosis in the 4-week period prior to death. Medical specialty and primary care visits without a mental health diagnosis were the most common visit types. The individuals more likely to make a visit in the year prior to death (p < 0.05) tended to be women, individuals of older age (65+ years), those where the neighborhood income was over $40,000 and 25 % were college graduates, and those who died by non-violent means.

CONCLUSIONS

This study indicates that opportunities for suicide prevention exist in primary care and medical settings, where most individuals receive services prior to death. Efforts may target improved identification of mental illness and suicidal ideation, as a large proportion may remain undiagnosed at death.

Human subject protections in genetic research

The Certificate of Confidentiality (COC) is a voluntary tool to protect researchers from being compelled to release identifying information about their subjects. Institutional review board (IRB) review and informed consent (IC) procedures are mandatory tools to protect human subjects. Although many studies reveal poor documentation of IRB and IC procurement, most published research undergoes IRB review and has appropriate IC procedures. There are no empirical data about the use of COCs. We examined the procurement and documentation of all these human subject protections in the genetics literature. A total of 112 (55%) articles documented IRB review, 108 (53%) document IC, and 82 (41%) documented both. None documented the procurement of a COC. Returned surveys provided additional information that confirmed that at least 74% (n = 150) of research had received appropriate IRB review, at least 71% (n = 143) had procured IC, and at least 10% (n = 21) had obtained a COC. An additional 22 respondents had procured COCs for other research, whereas 17 respondents were unaware of them and their purpose. In this era of public scrutiny of medical research, we recommend greater familiarity with and documentation of all human subject protections.

Ethical assessment of clinical asthma trials including children subjects

BACKGROUND

The inclusion of children with asthma in clinical asthma trials is increasing, including their participation in placebo-controlled trials (PCTs). The objectives of this study are to assess whether children with asthma have been harmed by their participation in PCTs.

METHODS

Seventy clinical asthma trials involving children published between January 1998 and December 2001 that involved distinct US research populations were identified. Studies were reviewed to determine whether all subjects with more than mild asthma received daily antiinflammatory medication as recommended by national guidelines. Sixty-two clinical asthma trials included data about subject withdrawal and were analyzed for the frequency of asthma exacerbations.

RESULTS

Forty-five studies were designed as PCTs and did not require that all subjects with more than mild asthma receive antiinflammatory medications. Of 24,953 subjects, 4653 (19%) for whom data are available withdrew from research, and 1247 subjects (9.4%) withdrew from PCTs due to asthma exacerbations compared with 358 subjects (3.1%) in other trials. In PCTs, subjects withdrew more frequently from the placebo arms than the active-treatment arms and did so more frequently because of an asthma exacerbation (667 or 15% vs 580 or 6.5%). Fifty-two studies enrolled both children and adults, although only 1 performed subset analysis of the children.

CONCLUSIONS

Subjects enrolled in PCTs of asthma have been exposed to unnecessary risks and harms. Clinical asthma trials involving children and adults do not benefit children as a class because they rarely provide subset analysis of children subjects.

Interactions of nitric oxide-derived reactive nitrogen species with peroxidases and lipoxygenases

Nitric oxide (NO) is a major free radical modulator of smooth muscle tone, which under basal conditions acts to preserve vascular homeostasis through its anti-inflammatory properties. The biochemistry of NO, in particular, its rapid conversion in vivo into secondary reactive nitrogen species (RNS), its chemical nature as a free radical and its high diffusibility and hydrophobicity dictate that this species will interact with numerous biomolecules and enzymes. In this review, we consider the interactions of a number of enzymes found in the vasculature with NO and NO-derived RNS. All these enzymes are either homeostatic or promote the development of atherosclerosis and hypertension. Therefore their interactions with NO and NO-derived RNS will be of central importance in the initiation and progression of vascular disease. In some examples, (e.g. lipoxygenase, LOX), such interactions provide catalytic 'sinks' for NO, but for others, in particular peroxidases and prostaglandin H synthase (PGHS), reactions with NO may be detrimental. Nitric oxide and NO-derived RNS directly modulate the activity of vascular peroxidases and LOXs through a combination of effects, including transcriptional regulation, altering substrate availability, and direct reaction with enzyme turnover intermediates. Therefore, these interactions will have two major consequences: (i) depletion of NO levels available to cause vasorelaxation and prevent leukocyte/platelet adhesion and (ii) modulation of activity of the target enzymes, thereby altering the generation of bioactive signaling molecules involved in maintenance of vascular homeostasis, including prostaglandins and leukotrienes.

Impaired functional activity of alveolar macrophages from GM-CSF-deficient mice

We hypothesized that pulmonary granulocyte-macrophage colony-stimulating factor (GM-CSF) is critically involved in determining the functional capabilities of alveolar macrophages (AM) for host defense. To test this hypothesis, cells were collected by lung lavage from GM-CSF mutant mice [GM(-/-)] and C57BL/6 wild-type mice. GM(-/-) mice yielded almost 4-fold more AM than wild-type mice. The percentage of cells positive for the beta(2)-integrins CD11a and CD11c was reduced significantly in GM(-/-) AM compared with wild-type cells, whereas expression of CD11b was similar in the two groups. The phagocytic activity of GM(-/-) AM for FITC-labeled microspheres was impaired significantly compared with that of wild-type AM both in vitro and in vivo (after intratracheal inoculation with FITC-labeled beads). Stimulated secretion of tumor necrosis factor-alpha (TNF-alpha) and leukotrienes by AM from the GM(-/-) mice was greatly reduced compared with wild-type AM, whereas secretion of monocyte chemoattractant protein-1 was increased. Transgenic expression of GM-CSF exclusively in the lungs of GM(-/-) mice resulted in AM with normal or supranormal expression of CD11a and CD11c, phagocytic activity, and TNF-alpha secretion. Thus, in the absence of GM-CSF, AM functional capabilities for host defense were significantly impaired but were restored by lung-specific expression of GM-CSF.

Peroxynitrite-induced nitrotyrosination of proteins is blocked by direct 5-lipoxygenase inhibitor zileuton

We have previously shown that the ability of overnight pretreatment with lipopolysaccharide (LPS) to suppress alveolar macrophage (AM) leukotrienes (LT) synthesis is explained by induction of nitric oxide (NO), and reactive oxygen intermediates (ROI). More recently we have demonstrated that the generation of peroxynitrite (ONOO-) from the combination of NO and ROI directly nitrotyrosinates the 5-lipoxygenase (5-LO) enzyme and reduces cell-free and intact AM 5-LO metabolism. This effect of ONOO- was associated with nitrotyrosination of the 5-LO enzyme in intact cells and after treatment of recombinant enzyme. We postulated that LPS treatment of cells resulted in activation of 5-LO with the generation of ROI, which in turn led to autoinactivation of the enzyme. In an effort to suppress ROI generated from activation of 5-LO we examined the effect of a direct 5-LO inhibitor on LPS-induced suppression of LT synthesis. Coincubation with the reversible 5-LO inhibitor zileuton during the LPS pretreatment of intact cells dose dependently blocked the inhibition of 5-LO metabolism by LPS. The effect of zileuton on LPS-induced suppression of LT synthesis was similar to that of N-monomethyl-L-arginine. Zileuton had no effect on inducible nitric-oxide synthase induction. Interestingly, zileuton blocked ONOO--induced nitrotyrosination of recombinant 5-LO in a cell-free system as well as of native enzyme in intact cells. Moreover, zileuton blocked the nitrotyrosination of other proteins. We conclude that the suppression of 5-LO activity occurring with LPS treatment can be blocked by zileuton. The mechanism by which zileuton is effective is in part explained by blocking nitrotyrosination of 5-LO.

Interleukin-8 stimulates human immunodeficiency virus type 1 replication and is a potential new target for antiretroviral therapy

Production of the C-X-C chemokines interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) in macrophages is stimulated by exposure to human immunodeficiency virus type 1 (HIV-1). We have demonstrated previously that GRO-alpha then stimulates HIV-1 replication in both T lymphocytes and macrophages. Here we demonstrate that IL-8 also stimulates HIV-1 replication in macrophages and T lymphocytes. We further show that increased levels of IL-8 are present in the lymphoid tissue of patients with AIDS. In addition, we demonstrate that compounds which inhibit the actions of IL-8 and GRO-alpha via their receptors, CXCR1 and CXCR2, also inhibit HIV-1 replication in both T lymphocytes and macrophages, indicating potential therapeutic uses for these compounds in HIV-1 infection and AIDS.

Catalytic consumption of nitric oxide by 12/15- lipoxygenase: inhibition of monocyte soluble guanylate cyclase activation

12/15-Lipoxygenase (LOX) activity is elevated in vascular diseases associated with impaired nitric oxide (( small middle dot)NO) bioactivity, such as hypertension and atherosclerosis. In this study, primary porcine monocytes expressing 12/15-LOX, rat A10 smooth muscle cells transfected with murine 12/15-LOX, and purified porcine 12/15-LOX all consumed *NO in the presence of lipid substrate. Suppression of LOX diene conjugation by *NO was also found, although the lipid product profile was unchanged. *NO consumption by porcine monocytes was inhibited by the LOX inhibitor, eicosatetraynoic acid. Rates of arachidonate (AA)- or linoleate (LA)-dependent *NO depletion by porcine monocytes (2.68 +/- 0.03 nmol x min(-1) x 10(6) cells(-1) and 1.5 +/- 0.25 nmol x min(-1) x 10(6) cells(-1), respectively) were several-fold greater than rates of *NO generation by cytokine-activated macrophages (0.1-0.2 nmol x min(-1) x 10(6) cells(-1)) and LA-dependent *NO consumption by primary porcine monocytes inhibited *NO activation of soluble guanylate cyclase. These data indicate that catalytic *NO consumption by 12/15-LOX modulates monocyte *NO signaling and suggest that LOXs may contribute to vascular dysfunction not only by the bioactivity of their lipid products, but also by serving as catalytic sinks for *NO in the vasculature.

Human immunodeficiency virus type 1 (HIV-1)-induced GRO-alpha production stimulates HIV-1 replication in macrophages and T lymphocytes

We examined the early effects of infection by CCR5-using (R5 human immunodeficiency virus [HIV]) and CXCR4-using (X4 HIV) strains of HIV type 1 (HIV-1) on chemokine production by primary human monocyte-derived macrophages (MDM). While R5 HIV, but not X4 HIV, replicated in MDM, we found that the production of the C-X-C chemokine growth-regulated oncogene alpha (GRO-alpha) was markedly stimulated by X4 HIV and, to a much lesser extent, by R5 HIV. HIV-1 gp120 engagement of CXCR4 initiated the stimulation of GRO-alpha production, an effect blocked by antibodies to CXCR4. GRO-alpha then fed back and stimulated HIV-1 replication in both MDM and lymphocytes, and antibodies that neutralize GRO-alpha or CXCR2 (the receptor for GRO-alpha) markedly reduced viral replication in MDM and peripheral blood mononuclear cells. Therefore, activation of MDM by HIV-1 gp120 engagement of CXCR4 initiates an autocrine-paracrine loop that may be important in disease progression after the emergence of X4 HIV.

Pathogenic yeasts Cryptococcus neoformans and Candida albicans produce immunomodulatory prostaglandins

Enhanced prostaglandin production during fungal infection could be an important factor in promoting fungal colonization and chronic infection. Host cells are one source of prostaglandins; however, another potential source of prostaglandins is the fungal pathogen itself. Our objective was to determine if the pathogenic yeasts Cryptococcus neoformans and Candida albicans produce prostaglandins and, if so, to begin to define the role of these bioactive lipids in yeast biology and disease pathogenesis. C. neoformans and C. albicans both secreted prostaglandins de novo or via conversion of exogenous arachidonic acid. Treatment with cyclooxygenase inhibitors dramatically reduced the viability of the yeast and the production of prostaglandins, suggesting that an essential cyclooxygenase like enzyme may be responsible for fungal prostaglandin production. A PGE series lipid was purified from both C. albicans and C. neoformans and was biologically active on both fungal and mammalian cells. Fungal PGE(x) and synthetic PGE(2) enhanced the yeast-to-hypha transition in C. albicans. Furthermore, in mammalian cells, fungal PGE(x) down-modulated chemokine production, tumor necrosis factor alpha production, and splenocyte proliferation while up-regulating interleukin 10 production. These are all activities previously documented for mammalian PGE(2). Thus, eicosanoids are produced by pathogenic fungi, are critical for growth of the fungi, and can modulate host immune functions. The discovery that pathogenic fungi produce and respond to immunomodulatory eicosanoids reveals a virulence mechanism that has potentially great implications for understanding the mechanisms of chronic fungal infection, immune deviation, and fungi as disease cofactors.

Evidence for significant differences in microsomal drug glucuronidation by canine and human liver and kidney

The in vitro glucuronidation of a range of structurally diverse chemicals has been studied in hepatic and renal microsomes from human donors and the beagle dog. These studies were undertaken to improve on the limited knowledge of glucuronidation by the dog and to assess its suitability as a model species for pharmacokinetic studies. In general, the compounds studied were glucuronidated severalfold more rapidly (based on intrinsic clearance estimates) by DLM than by HLM. Intrinsic clearance values for human UGT1A1 and UGT2B7 substrates were an order of magnitude higher in DLM than in HLM (e.g., gemfibrozil: 31 microl/min/mg versus 3.0 microl/min/mg; ketoprofen: 2.4 microl/min/mg versus 0.2 microl/min/mg). There were also drug-specific differences. HLM readily glucuronidated propofol (2.4 microl/min/mg) whereas DLM appeared unable to glucuronidate this drug directly. Regioselective differences in morphine glucuronidation were also apparent. Human kidney microsomes catalyzed the glucuronidation of many xenobiotics, although glucuronidation of the endobiotic bilirubin was not detectable in this tissue. In direct contrast, dog kidney microsomes glucuronidated bilirubin only (no glucuronidation of all other xenobiotics was detected). These preliminary studies indicated significant differences in the glucuronidation of xenobiotics by microsomes from the livers and kidneys of human and dog and should be confirmed using a larger panel of tissues from individual dogs. Early knowledge of the relative rates of in vitro glucuronidation, the UGTs responsible for drug glucuronidation, and their tissue distribution in different species could assist the design and analysis of preclinical pharmacokinetic and safety evaluation studies.

Prolonged exposure to lipopolysaccharide inhibits macrophage 5-lipoxygenase metabolism via induction of nitric oxide synthesis

LPS from bacteria can result in the development of sepsis syndrome and acute lung injury. Although acute exposure to endotoxin primes leukocytes for enhanced synthesis of leukotrienes (LT), little is known about the effect of chronic exposure. Therefore, we determined the effect of prolonged LPS treatment on 5-lipoxygenase (5-LO) metabolism of arachidonic acid in alveolar macrophages (AM) and in peripheral blood monocytes. Pretreatment of AM with LPS caused time- and dose-dependent suppression of LT synthetic capacity. LPS pretreatment failed to inhibit arachidonic acid (AA) release. The fact that LPS inhibited LT synthesis from endogenous AA more than from exogenous AA suggested an effect on 5-LO-activating protein (FLAP). In addition, an inhibitory effect of LPS treatment on AM 5-LO activity was suggested by cell-free 5-LO enzyme assay. No effect on the expression of either 5-LO or FLAP proteins was observed. New protein synthesis was necessary for LPS-induced reduction of 5-LO metabolism in AM, and immunoblotting demonstrated marked induction of NO synthase (NOS). Inhibition by LPS was reproduced by an NO donor and was abrogated by inhibitors of constitutive and inducible NOS. Compared with AM, peripheral blood monocytes exhibited no suppression by LPS of 5-LO metabolism and no induction of inducible NOS. We conclude that prolonged exposure to LPS impairs AM 5-LO metabolism by NO-mediated suppression of both 5-LO and FLAP function. Because LT contribute to antimicrobial defense, this down-regulation of 5-LO metabolism may contribute to the increased susceptibility to pneumonia in patients following sepsis.

GM-CSF regulates bleomycin-induced pulmonary fibrosis via a prostaglandin-dependent mechanism

To characterize the role of GM-CSF in pulmonary fibrosis, we have studied bleomycin-induced fibrosis in wild-type mice vs mice with a targeted deletion of the GM-CSF gene (GM-CSF-/- mice). Without GM-CSF, pulmonary fibrosis was worse both histologically and quantitatively. These changes were not related to enhanced recruitment of inflammatory cells because wild-type and GM-CSF-/- mice recruited equivalent numbers of cells to the lung following bleomycin. Interestingly, recruitment of eosinophils was absent in GM-CSF-/- mice. We investigated whether the enhanced fibrotic response in GM-CSF-/- animals was due to a deficiency in an endogenous down-regulator of fibrogenesis. Analysis of whole lung homogenates from saline- or bleomycin-treated mice revealed that GM-CSF-/- animals had reduced levels of PGE2. Additionally, alveolar macrophages were harvested from wild-type and GM-CSF-/- mice that had been exposed to bleomycin. Although bleomycin treatment impaired the ability of alveolar macrophages from wild-type mice to synthesize PGE2, alveolar macrophages from GM-CSF-/- mice exhibited a significantly greater defect in PGE2 synthesis than did wild-type cells. Exogenous addition of GM-CSF to alveolar macrophages reversed the PGE2 synthesis defect in vitro. Administration of the PG synthesis inhibitor, indomethacin, to wild-type mice during the fibrogenic phase postbleomycin worsened the severity of fibrosis, implying a causal role for PGE2 deficiency in the evolution of the fibrotic lesion. These data demonstrate that GM-CSF deficiency results in enhanced fibrogenesis in bleomycin-induced pulmonary fibrosis and indicate that one mechanism for this effect is impaired production of the potent antifibrotic eicosanoid, PGE2.

Patterns of organochlorine pesticide contamination in neotropical migrant passerines in relation to diet and winter habitat

Eleven species of Neotropical migrant passerines collected in Illinois (USA) during May 1996, were analyzed for the presence of organochlorine (OC) pesticides. At least one of five OC pesticide residues was detected in 66 of 72 birds, representing all species examined. The contaminants most frequently detected were p,p'-DDE, dieldrin and heptachlor epoxide, all of which were present in the 10-30 ng/g range. Insectivores had significantly higher levels of these compounds than did non-insectivores, while there was no significant main effect of winter habitat (forest and scrub). Future research on OC pesticide contamination in resident New World passerines may allow more accurate predictions regarding the sources of contamination in Neotropical migrants.

Transcriptional induction of bilirubin UDP-glucuronosyltransrase by ethanol in rat liver

Several drug-metabolizing enzymes including bilirubin UDP-glucuronosyltransferase (UGT1A1) are influenced by long-term ethanol consumption. In the present study, the activity and expression of UGT1A1 were investigated in livers of ethanol-treated rats. Animals were treated daily for 15 days with ethanol or isocaloric amount of glucose solution by gastric intubation. Microsomes and total RNA were prepared from the liver of rats and analyzed by Western blot and Northern hybridization using UGT1A1 specific antibody and cDNA probe. Microsomal bilirubin UGT activity was also measured. The elevation of UGT1A1 mRNA was observed in the liver of ethanol consumer animals with the simultaneous increase in microsomal UGT1A1 protein leading to stimulated bilirubin glucuronidation both in vivo and in microsomal vesicles. These results arise the possibility of the transcriptional induction and/or the mRNA stabilization by ethanol consumption, which can be caused by ethanol itself or the metabolic changes due to the treatment.

Intersexes in Mississippi River shovelnose sturgeon sampled below Saint Louis, Missouri, USA

The Missouri Department of Conservation detected high organochlorine levels in tissues of fish from the Mississippi River south of Saint Louis. Chlordane, which is both a carcinogen and an endocrine disrupter, reached 2960 micrograms/kg in fillets of shovelnose sturgeon, Scaphirhynchus platyorynchus, and 1926 micrograms/kg in their roe, wet weight basis. Polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (DDE) in roe have reached 5810 and 780 micrograms/kg, respectively. The purpose of this study was to determine if endocrine disrupters and carcinogens are a potential cause of the significantly diminished reproduction capacity and population declines in the endangered pallid sturgeon, Scaphirhynchus albus. Twenty-four surrogate shovelnose sturgeons were sampled north of Saint Louis where contaminant levels were lower compared with 17 sampled south of Saint Louis where contaminant levels were high. Liver and gonad tissues were formalin-fixed, histologically processed and examined. Neoplasms were not found. The principal finding was that the testes of two of the seven downstream male fish contained ovigerous lamellae, in addition to mature sperm. Since sturgeons are gonochoristic and intersexes are rare and unusual, the occurrence of intersex in 29% of the male Mississippi River shovelnose sturgeon examined from a population contaminated with chlordane and other chemicals raise concern for human health, species biodiversity and preservation of waterway quality. These findings, however, need to be corroborated by expanded studies with a higher sample size.

Granulocyte-macrophage colony-stimulating factor upregulates reduced 5-lipoxygenase metabolism in peripheral blood monocytes and neutrophils in acquired immunodeficiency syndrome

Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway, which play a role in host defense, and are synthesized by both monocytes (peripheral blood monocyte [PBM]) and neutrophils (PMN). Because 5-LO metabolism is reduced in alveolar macrophages and PMN from acquired immunodeficiency syndrome (AIDS) subjects, we investigated the synthesis of LT by PBM and PMN from these subjects. There was a reduction (74.2% +/- 8.8% of control) in LT synthesis in PBM from human immunodeficiency virus (HIV)-infected compared with normal subjects. Expression of 5-LO (51.2% +/- 8.8% of control), and 5-LO activating protein (FLAP) (48.5% +/- 8.0% of control) was reduced in parallel. We hypothesized that this reduction in LT synthetic capacity in PBM and PMN was due to reduced cytokine production by CD4 T cells, such as granulocyte-macrophage colony-stimulating factor (GM-CSF). We treated 10 AIDS subjects with GM-CSF for 5 days. PBM 5-LO metabolism ex vivo was selectively increased after GM-CSF therapy and was associated with increased 5-LO and FLAP expression. PMN leukotriene B(4) (LTB(4)) synthesis was also augmented and associated with increased 5-LO, FLAP, and cytosolic phospholipase A(2) expression. In conclusion, as previously demonstrated for PMN, PBM from AIDS subjects also demonstrate reduced 5-LO metabolism. GM-CSF therapy reversed this defect in both PBM and PMN. In view of the role of LT in antimicrobial function, cytokine administration in AIDS may play a role as adjunct therapy for infections.

TNF-alpha inhibits HIV-1 replication in peripheral blood monocytes and alveolar macrophages by inducing the production of RANTES and decreasing C-C chemokine receptor 5 (CCR5) expression

The pathogenesis of HIV-1 infection is influenced by the immunoregulatory responses of the host. Macrophages present in the lymphoid tissue are susceptible to infection with HIV-1, but are relatively resistant to its cytopathic effects and serve as a reservoir for the virus during the course of disease. Previous investigators have demonstrated that increased serum levels of TNF-alpha contribute to the clinical symptoms of AIDS and that TNF-alpha stimulates the production of HIV-1 in chronically infected lymphocytic and monocytic cell lines by increasing HIV-1 gene expression. Although previous studies have suggested that TNF-alpha may increase HIV-1 infection of primary human mononuclear cells, some recent studies have indicated that TNF-alpha suppresses HIV-1 infection of macrophages. We now demonstrate that TNF-alpha suppresses HIV-1 replication in freshly infected peripheral blood monocytes (PBM) and alveolar macrophages (AM) in a dose-dependent manner. As TNF-alpha has been shown to increase the production of C-C chemokine receptor (CCR5)-binding chemokines under certain circumstances, we hypothesized that TNF-alpha inhibits HIV-1 replication by increasing the expression of these HIV-suppressive factors. We now show that TNF-alpha treatment of PBM and AM increases the production of the C-C chemokine, RANTES. Immunodepletion of RANTES alone or in combination with macrophage inflammatory protein-1alpha and -1beta block the ability of TNF-alpha to suppress viral replication in PBM and AM. In addition, we found that TNF-alpha treatment reduces CCR5 expression on PBM and AM. These findings suggest that TNF-alpha plays a significant role in inhibiting monocytotropic strains of HIV-1 by two distinct, but complementary, mechanisms.

Regulation of 5-lipoxygenase metabolism in mononuclear phagocytes by CD4 T lymphocytes

Alveolar macrophages (AM) are the primary resident effector cells in the alveolus. Leukotrienes (LT) are secreted by AM in their role as defender of the lung. 5-Lipoxygenase (5-LO) catalyzes the synthesis of LT in association with 5-LO-activating protein, termed "FLAP." AM demonstrate increased 5-LO metabolism compared to peripheral blood monocytes (PBM). Activated lymphocytes release mediators which upregulate 5-LO metabolism in PBM. The lymphocyte population of the lung consists predominantly of CD4+ helper constitutively "activated" T cells. We hypothesized that mediators released by pulmonary CD4+ T cells may upregulate and maintain of 5-LO metabolism in PBM as they enter the alveolar space and differentiate into AM. 5-LO metabolism in AM from CD4-depleted mice demonstrated reduced LT synthesis (LTC4: 66.9 +/- 8%; LTB4 61.4 +/- 6.2% control). The decrease in 5-LO metabolism was associated with reduced FLAP (30.1 +/- 14.5% of control) and 5-LO expression (49 +/- 13.7% of control). This defect in AM 5-LO metabolism in CD4-depleted mice was further associated with reduced LTC4 levels in bronchoalveolar lavage (BAL) fluid. In summary, factors secreted constitutively by lung lymphocytes, in particular CD4 cells, contribute to the increased 5-LO metabolism in AM.

Molecular basis of bilirubin UDP-glucuronosyltransferase induction in spontaneously diabetic rats, acetone-treated rats and starved rats

The co-ordinated induction of several hepatic drug-metabolizing enzymes is a common feature in the regulation of drug biotransformation under normal and pathological conditions. In the present study the activity and expression of bilirubin UDP-glucuronosyltransferase (UGT1A1) were investigated in livers of BioBreeding/Worcester diabetic, fasted and acetone-treated rats. Bilirubin glucuronidation was stimulated by all three treatments; this was correlated with an increase in the UGT1A1 protein concentration in hepatic microsomes. Transcriptional induction of UGT1A1 was also observed in diabetes and starvation but not with acetone treatment, which apparently caused translational stabilization of the enzyme protein. The hormonal/metabolic alterations in diabetes and starvation might be a model for postnatal development. The sudden interruption of maternal glucose supply signals the enhanced expression of UGT1A1, giving a novel explanation for the physiological induction of bilirubin glucuronidation in newborn infants.

Alveolar lining fluid regulates mononuclear phagocyte 5-lipoxygenase metabolism

The enzyme 5-lipoxygenase (5-LO) catalyses the synthesis of leukotrienes (LT), which are important in phagocytosis and killing of microorganisms. The alveolar macrophage (AM), the primary resident defender of the alveolar space, has a greater capacity for LT synthesis than its precursor, the peripheral blood monocyte (PBM). This study investigated whether the alveolar lining fluid (ALF) upregulates LT synthetic capacity in mononuclear phagocytes. Rat AM, peritoneal macrophages (PM) and ALF were obtained by lavage from pathogen-free animals. Human PBM were isolated from normal subjects. 5-LO metabolism and expression were measured with and without ALF. Rat ALF increased 5-LO metabolism (136.4+/-15.1% of control) in cultured PBM. This was associated with increased 5-LO activating protein (FLAP) (357+/-29.5 %), and 5-LO expression (188+/-31.3%). Culture of AM for 3 days resulted in a greater decrement in LTB4 synthesis (LTB4 15.4+/-6.9% of day 1) than in PM (54.7+/-8.3% of day 1), suggesting a greater dependence of AM 5-LO metabolism on ALF. 5-LO and FLAP expression decreased to a greater degree in AM than PM in culture. Furthermore, AM cultured with ALF maintained their LT synthetic capacity, FLAP and 5-LO expression compared with control cells cultured in medium alone. In conclusion, alveolar lining fluid increased 5-lipoxygenase metabolism in peripheral blood monocytes and maintained it in cultured alveolar macrophages, by a mechanism of increased 5-lipoxygenase and 5-lipoxygenase activating protein expression. This may boost host defence capabilities.

Granulocyte colony-stimulating factor administration to HIV-infected subjects augments reduced leukotriene synthesis and anticryptococcal activity in neutrophils

Neutrophil (PMN) dysfunction occurs in HIV infection. Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway that play a role in host defense and are synthesized by PMN. We investigated the synthesis of LT by PMN from HIV-infected subjects. There was a reduction (4.0+/-1.3% of control) in LT synthesis in PMN from HIV-infected compared with normal subjects. This was associated with reduced expression of 5-LO-activating protein (31.2+/-9.6% of normal), but not of 5-LO itself. Since HIV does not directly infect PMN, we considered that these effects were due to reduced release of cytokines, such as granulocyte colony-stimulating factor (G-CSF). We examined the effect of G-CSF treatment (300 microgram daily for 5 d) on eight HIV-infected subjects. PMN were studied in vitro before therapy (day 1) and on days 4 and 7. LTB4 synthesis was increased on day 4 of G-CSF treatment, and returned toward day 1 levels on day 7. 5-LO and 5-LO-activating protein expression were increased in parallel. As a functional correlate to this increase in PMN LT synthesis by G-CSF, we examined the effects on killing of Cryptococcus neoformans. Anticryptococcal activity of PMN from HIV-infected subjects was less than that of PMN from normal subjects. G-CSF treatment improved fungistatic activity of PMN. This increase in antifungal activity was attenuated by in vitro treatment with the LT synthesis inhibitor, MK-886. In conclusion, PMN from HIV-infected subjects demonstrate reduced 5-LO metabolism and antifungal activity in vitro, which was reversed by in vivo G-CSF therapy.

Regulation of 5-lipoxygenase activity in mononuclear phagocytes: characterization of an endogenous cytosolic inhibitor

The proinflammatory leukotrienes (LT) play important roles in host defense and disease states. However, no endogenous mechanisms to downregulate 5-lipoxygenase (5-LO), the enzyme catalyzing LT synthesis, have been described. We observed that the cytosolic fraction of rat alveolar macrophages (AMs) and peritoneal macrophages (PMs), and of peripheral blood monocytes (PBMs) contain substantial amounts of 5-LO protein, but little detectable 5-LO activity. We therefore examined these mononuclear phagocyte (MNP) cytosolic fractions for inhibitory activity against 5-LO. MNP cytosol dose-dependently reduced the 5-LO activity in neutrophil (PMN) cytosol and AM membrane. Furthermore, MNP cytosol dose-dependently prolonged the lag phase of soybean lipoxygenase (LO) without affecting the rate of product formation. This effect was overcome by subsequent addition of 13(S)-hydroperoxy-9-cis-11-trans-octadecadienoic acid (13-HpOD), suggesting that the active factor scavenges hydroperoxides. Inactivation by boiling and roteinase K suggest that is a protein. We speculate that this cytosolic factor(s) may serve as an endogenous means for the down-regulation of 5-LO in macrophages.

RANTES inhibits HIV-1 replication in human peripheral blood monocytes and alveolar macrophages

Infection with human immunodeficiency virus (HIV)-1 most often leads to the development of acquired immune deficiency syndrome, which may manifest with opportunistic infections, many of which occur in the lung. Mononuclear phagocytes infected by HIV-1, being relatively resistant to its cytopathic effects, potentially act as a reservoir for the virus. The alveolar macrophage (AM), a differentiated lung tissue macrophage, is readily infected by HIV-1, after which the virus becomes relatively dormant. C-C chemokines, secreted by CD8 T lymphocytes and other cells, are known to suppress HIV replication in lymphocytes. In view of this observation, and the relative increase in CD8+ T lymphocytes during HIV-1 disease, particularly in the lung, we hypothesized that C-C chemokines might play a key role in suppressing HIV-1 replication in AM. We examined the effect of the C-C chemokines macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and regulated on activation normal T cell expressed and secreted (RANTES) singly and in combination on HIV-1 replication in peripheral blood monocytes (PBM) and AM infected in vitro. Our findings indicate that RANTES suppresses HIV-1 replication, as measured by reverse transcriptase activity, in PBM (41.3 +/- 15.2% of control, n = 3, P < 0.05) and AM (30.3 +/- 7.8% of control, n = 3, P < 0.05) in a dose-dependent manner. The other C-C chemokines had no significant effect singly (MIP-1 alpha PBM: 64.8 +/- 21.9%; AM: 115.0 +/- 2.4% of control; MIP-1 beta PBM: 68 +/- 19.6; AM: 63.3 +/- 26.2% of control) but modestly decreased HIV replication when incubated in addition to RANTES (24.5 +/- 6.5% of control). These observations suggest that RANTES plays a key role in modulating HIV-1 replication in mononuclear phagocytes in the blood and lung, and this may have therapeutic implications for prevention and/or treatment of HIV disease.

Increased 5-lipoxygenase metabolism in the lungs of human subjects exposed to ozone

The environmental pollutant ozone, at sufficiently high levels, is known to induce pulmonary inflammation with resultant airway obstruction in normal subjects. Eicosanoids comprise one group of mediators released from alveolar macrophages which are involved in the pathogenesis of inflammatory lung diseases. We compared the effects of 2-h exposures to 0.4 ppm ozone and filtered air on pulmonary function and eicosanoid levels in bronchoalveolar lavage fluid in 11 normal healthy volunteers. Subjects were exposed to a 6-fold increase in minute ventilation using an adjusted work load on a cycle ergometer. All subjects complained of cough and dyspnea, and demonstrated increased airway obstruction, and increased specific airway resistance following ozone exposure as compared to air exposure. Bronchoalveolar lavage cell count demonstrated a 9-fold increase in the number of neutrophils with a lesser reduction in the number of alveolar macrophages following ozone exposure. Notably, bronchoalveolar lavage fluid leukotriene (LT) C4 (8-fold) and to a lesser extent LTB4 (1.5-fold) levels were higher following ozone exposure compared to air control, with no change in prostaglandins. In a subset of four subjects, alveolar macrophage arachidonic acid metabolism was studied in vitro following separate in vivo exposures to both ozone and air. Alveolar macrophages obtained following ozone exposure released more 5-lipoxygenase (1.5-fold) metabolites, with no change in cyclooxygenase metabolites, than did cells obtained following air exposure. These observations document activation of the 5-lipoxygenase pathway in the lung following ozone exposure, and suggest that alveolar macrophages may participate in the generation of LT, whose actions promote airway inflammation and obstruction.

Leukotriene-deficient mice manifest enhanced lethality from Klebsiella pneumonia in association with decreased alveolar macrophage phagocytic and bactericidal activities

Leukotrienes (LTs) are potent mediators of inflammation derived from the 5-lipoxygenase pathway of arachidonic acid metabolism. Although they are known to enhance leukocyte recruitment and function, their role in antimicrobial host defense has not been established. To determine the role of endogenous LTs in the host response to pulmonary infection, wild-type mice and mice rendered LT-deficient by targeted disruption of the 5-lipoxygenase gene (knockout mice) were studied following intratracheal challenge with Klebsiella pneumoniae. Wild-type mice demonstrated a marked increase in lung LT levels and neutrophil numbers following bacterial challenge. As compared with wild-type animals, knockout animals manifested a greater degree of lethality as well as bacteremia following challenge. Interestingly, they displayed no defect in neutrophil recruitment to the lung. However, alveolar macrophages from knockout animals exhibited impairments in bacterial phagocytosis and killing, and these defects were overcome by in vitro addition of exogenous LTB4. We conclude that endogenous LTs play a critical role in the defense against bacterial pneumonia in this murine model.

Leukotriene-deficient mice manifest enhanced lethality from Klebsiella pneumonia in association with decreased alveolar macrophage phagocytic and bactericidal activities

Leukotrienes (LTs) are potent mediators of inflammation derived from the 5-lipoxygenase pathway of arachidonic acid metabolism. Although they are known to enhance leukocyte recruitment and function, their role in antimicrobial host defense has not been established. To determine the role of endogenous LTs in the host response to pulmonary infection, wild-type mice and mice rendered LT-deficient by targeted disruption of the 5-lipoxygenase gene (knockout mice) were studied following intratracheal challenge with Klebsiella pneumoniae. Wild-type mice demonstrated a marked increase in lung LT levels and neutrophil numbers following bacterial challenge. As compared with wild-type animals, knockout animals manifested a greater degree of lethality as well as bacteremia following challenge. Interestingly, they displayed no defect in neutrophil recruitment to the lung. However, alveolar macrophages from knockout animals exhibited impairments in bacterial phagocytosis and killing, and these defects were overcome by in vitro addition of exogenous LTB4. We conclude that endogenous LTs play a critical role in the defense against bacterial pneumonia in this murine model.

5-Lipoxygenase metabolism in alveolar macrophages from subjects infected with the human immunodeficiency virus

Pulmonary infection represents a major source of morbidity and mortality in AIDS. One important component of pulmonary host defense is the elaboration by resident alveolar macrophages (AM) of proinflammatory leukotrienes (LT) and other 5-lipoxygenase (5-LO) metabolites of arachidonic acid (AA). In this study, we compared the 5-LO metabolic capacity of AM isolated from normal controls with two groups of HIV-infected subjects: (1) patients with low CD4 counts undergoing diagnostic evaluation for pulmonary indications, and (2) volunteers without pulmonary complaints stratified into normal (&gt; 500) and low (&lt; 200) CD4 count groups. Compared with AM from control subjects, AM from HIV-infected subjects with normal and low CD4 counts demonstrated a marked reduction in LT synthesis. This reduced metabolic capacity could not be attributed to in vivo activation because there was no increase in lavage fluid LTB4 levels. However, there was a reduction (approximately twofold) in 5-LO protein expression in both the normal and the low CD4 subsets. 5-LO-activating protein (FLAP) expression was unchanged in cells from the normal CD4 HIV group, but was decreased threefold in the two groups with low CD4 counts. These observations indicate that there is a graded defect in the 5-LO metabolic capacity of AM from HIV-infected subjects, with decreased expression of only 5-LO in the normal CD4 group, and decreased expression of both 5-LO and FLAP in the low CD4 group. This defect would be expected to compound the immunosuppression seen in these subjects.

5-Lipoxygenase metabolism in alveolar macrophages from subjects infected with the human immunodeficiency virus

Pulmonary infection represents a major source of morbidity and mortality in AIDS. One important component of pulmonary host defense is the elaboration by resident alveolar macrophages (AM) of proinflammatory leukotrienes (LT) and other 5-lipoxygenase (5-LO) metabolites of arachidonic acid (AA). In this study, we compared the 5-LO metabolic capacity of AM isolated from normal controls with two groups of HIV-infected subjects: (1) patients with low CD4 counts undergoing diagnostic evaluation for pulmonary indications, and (2) volunteers without pulmonary complaints stratified into normal (> 500) and low (< 200) CD4 count groups. Compared with AM from control subjects, AM from HIV-infected subjects with normal and low CD4 counts demonstrated a marked reduction in LT synthesis. This reduced metabolic capacity could not be attributed to in vivo activation because there was no increase in lavage fluid LTB4 levels. However, there was a reduction (approximately twofold) in 5-LO protein expression in both the normal and the low CD4 subsets. 5-LO-activating protein (FLAP) expression was unchanged in cells from the normal CD4 HIV group, but was decreased threefold in the two groups with low CD4 counts. These observations indicate that there is a graded defect in the 5-LO metabolic capacity of AM from HIV-infected subjects, with decreased expression of only 5-LO in the normal CD4 group, and decreased expression of both 5-LO and FLAP in the low CD4 group. This defect would be expected to compound the immunosuppression seen in these subjects.

Effects of granulocyte-macrophage colony-stimulating factor on eicosanoid production by mononuclear phagocytes

Granulocyte-macrophage CSF (GM-CSF) primes granulocytes for leukotriene (LT) synthesis. Here, we examined the effects of GM-CSF on arachidonic acid (AA) metabolism in rat alveolar macrophages (AM), peritoneal macrophages, and human peripheral blood monocytes. Pretreatment of AMs with GM-CSF for 24 h significantly increased the synthesis of immunoreactive LTB4 upon subsequent stimulation with calcium ionophore. Enhanced LT synthesis required a minimum of 6 h of GM-CSF pretreatment, suggesting that protein synthesis was required for enhanced LT production; indeed, cycloheximide completely abolished the GM-CSF effect on LT synthesis. HPLC analysis confirmed that GM-CSF primed AMs for enhanced generation of LTB4, as well as the 5-lipoxygenase products LTC, and 5-HETE. Moreover, parallel increases in other AA metabolites and free AA were observed following GM-CSF pretreatment. The enhanced production of all AA metabolites indicated that GM-CSF up-regulated AA release. Consistent with this, whole cell lysates from GM-CSF-treated AMs demonstrated increased phospholipase A2 (PLA2) activity. The increased activity was resistant to DTT, indicating the involvement of a PLA2 other than the 14-kDa PLA2s. By immunoblot analysis, GM-CSF treatment caused an increase in the 85-kDa PLA2 protein comparable to the observed increase in PLA2 activity. Unlike AMs, neither peritoneal macrophages nor peripheral blood monocytes showed increased eicosanoid generation or increased expression of the 85-kDa PLA2 protein following GM-CSF pretreatment. These results indicate that GM-CSF increases the capacity of AMs, but not peritoneal macrophages or peripheral blood monocytes, to generate eicosanoids. This effect results from increased PLA2 activity, due at least in part to increased levels of the 85-kDa PLA2 protein.

Effects of granulocyte-macrophage colony-stimulating factor on eicosanoid production by mononuclear phagocytes

Granulocyte-macrophage CSF (GM-CSF) primes granulocytes for leukotriene (LT) synthesis. Here, we examined the effects of GM-CSF on arachidonic acid (AA) metabolism in rat alveolar macrophages (AM), peritoneal macrophages, and human peripheral blood monocytes. Pretreatment of AMs with GM-CSF for 24 h significantly increased the synthesis of immunoreactive LTB4 upon subsequent stimulation with calcium ionophore. Enhanced LT synthesis required a minimum of 6 h of GM-CSF pretreatment, suggesting that protein synthesis was required for enhanced LT production; indeed, cycloheximide completely abolished the GM-CSF effect on LT synthesis. HPLC analysis confirmed that GM-CSF primed AMs for enhanced generation of LTB4, as well as the 5-lipoxygenase products LTC, and 5-HETE. Moreover, parallel increases in other AA metabolites and free AA were observed following GM-CSF pretreatment. The enhanced production of all AA metabolites indicated that GM-CSF up-regulated AA release. Consistent with this, whole cell lysates from GM-CSF-treated AMs demonstrated increased phospholipase A2 (PLA2) activity. The increased activity was resistant to DTT, indicating the involvement of a PLA2 other than the 14-kDa PLA2s. By immunoblot analysis, GM-CSF treatment caused an increase in the 85-kDa PLA2 protein comparable to the observed increase in PLA2 activity. Unlike AMs, neither peritoneal macrophages nor peripheral blood monocytes showed increased eicosanoid generation or increased expression of the 85-kDa PLA2 protein following GM-CSF pretreatment. These results indicate that GM-CSF increases the capacity of AMs, but not peritoneal macrophages or peripheral blood monocytes, to generate eicosanoids. This effect results from increased PLA2 activity, due at least in part to increased levels of the 85-kDa PLA2 protein.

Generation of active oxygen in elicited cells of Arabidopsis thaliana is mediated by a NADPH oxidase-like enzyme

Suspension-cultured cells of Arabidopsis thaliana generated active oxygen species (AOS) (measured by luminol-dependent chemiluminescence) following challenge with the bacterial protein elicitor harpin or the protein kinase activator phorbol 12-myristate 13-acetate. These responses were blocked by inhibitors of superoxide dismutase (SOD), NADPH oxidase and protein kinase. Harpin treatment also resulted in an increase in cell death, a response reduced by inhibitors of AOS generation or AOS scavengers. Extracellular SOD activity was found to be present in cell culture medium. Immunoblotting of Arabidopsis extracts revealed the presence of proteins immunologically related to the human neutrophil NADPH oxidase complex, and cell-free reconstitution assays showed that human neutrophil cytosol combined with Arabidopsis membranes could initiate superoxide generation. These data suggest that the enzyme catalysing the generation of superoxide in elicited Arabidopsis cells is similar to the mammalian NADPH oxidase and that a signalling cascade leading to AOS generation involves protein phosphorylation.