Surgical treatment of gastric outlet obstruction from a large trichobezoar: A case report.

INTRODUCTION: Bezoars are concretions of foreign indigestible material accumulating in the gastrointestinal tract leading to intraluminal mass formation that impairs the gastrointestinal motility and can lead to gastric obstruction of the small or the large bowel. There are different types of bezoars, named according to the material they are made of. These include phytobezoar, lactobezoar, pharmacobezoar, trichobezoar, and polybezoar. Trichobezoars (hair ball) are usually located in the stomach but may extend through the pylorus into the duodenum and small bowel (Rapunzel syndrome). CASE PRESENTATION: Herein, we report a case of a young adult female known to have a long-standing trichophagia who presented with gastric outlet obstruction due to a large trichobezoar. Endoscopy revealed a large and hard gastric trichobezoar not amenable to endoscopic retrieval leading to surgical extraction as a last resort. DISCUSSION: They are almost always associated with trichotillomania and trichophagia or other psychiatric disorders. Trichobezoar can be treated either surgically by laparotomy/laparoscopy or by endoscopic intervention. CONCLUSION: Treatment should be coupled to psychiatric evaluation and therapy to prevent recurrence.

Hepatic Sinusoidal Obstruction Syndrome in a child after chemotherapy for medulloblastoma.

Hepatic Sinusoidal Obstruction Syndrome (HSOS), the new name given to veno-occlusive disease (VOD) of the liver, is a well-known complication of high-dose chemotherapy employed with hematopoietic stem cell transplantation, but it has rarely been observed in children who receive conventional chemotherapy. HSOS following standard chemotherapy has been reported in patients receiving vincristine, actinomycin D, and cyclophosphamide for the treatment of Wilms tumor and more rarely rhabdomyosarcoma. We report a 14-year-old boy with high risk medulloblastoma treated with craniospinal radiation followed by chemotherapy, who experienced severe HSOS after only one course of chemotherapy including carboplatin, vincristine, and cyclophosphamide. To our knowledge, this is the second report of HSOS after standard dose chemotherapy for brain tumor in childhood.

Allogeneic stem cell transplantation for Glanzmann thrombasthenia.

Glanzmann thrombasthenia (GT) is a rare autosomal recessive bleeding disorder characterized by normal platelet count, but lack of platelet aggregation. The molecular basis is linked to quantitative and/or qualitative abnormalities of the membrane glycoprotein IIb/IIIa complexes. Usually it is associated with mild bleeding but may lead to severe and potentially fatal hemorrhages. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment. However, because of the risks associated with HSCT, it is generally not recommended unless there are life threatening hemorrhages, or the patient has developed refractoriness to platelet transfusion due to antibody formation. Herein, we report an 11-year-old female from United Arab Emirates (UAE) with severe GT and anti platelet alloimmunization successfully treated with HSCT from her HLA-identical sibling.

Expression of cyclooxygenase-1 and 2 in naturally-occurring canine cancer.

The purpose of this work was to determine cox-1 and cox-2 expression by immunohistochemistry in forms of naturally occurring canine cancer in order to identify animal systems for pre-clinical evaluation of cox inhibitors and cox-2 inhibitors in cancer. Canine lymphoma (LSA), prostatic carcinoma (PCA), osteosarcoma (OSA), oral melanoma (MEL), oral squamous cell carcinoma (SCC), oral fibrosarcoma (FSA), mammary carcinoma (MCA), and normal tissues were included. Cox-2 was expressed in epithelial tumors (17 of 26 SCC, 8 of 13 MCA, 5 of 9 PCA cases) and MEL (9 of 15 cases), but was generally absent in normal tissues. Cox-2 expression was minimal or absent in mesenchymal tumors and LSA. Cox-1 was expressed in normal epithelial tissues and in some osteoclast and osteoblast in bone, but was absent in normal lymph node. In conclusion, forms of canine cancer were identified for in vivo studies of the effects of cox inhibitors and selective cox-2 inhibitors on cancer.

Isolation and characterization of canine satellite cells.

Satellite cells were isolated from biopsies of the biceps femoris of adult dogs. Virtually all cells expressed muscle-specific proteins. Proliferation of satellite cells increased as the concentration of fetal calf serum (FCS) was increased from 1 to 10% of the basal medium. The addition of mitogenic growth factors resulted in greater proliferation than that of cells cultured in basal medium alone. Maximum proliferation was obtained when fibroblast growth factor-basic (FGF2) was added to the medium, but differences existed between sources or types. Proliferation did not plateau when the concentration of recombinant human FGF2 was 75 ng/ml but reached maximum levels when 50 ng/ml of bovine FGF2 or 10 ng/ml of growth hormone or insulin-like growth factor-1 were added to the medium. Proliferation of satellite cells decreased when more than 5 ng/ml of transforming growth factor-alpha was included in the medium. Exposure of canine satellite cells to chemically defined media induced greater fusion of total nuclei (ODM-34%; 4F, ITT-CF, and SFG-23%) than exposure to other treatments, such as basal medium plus 2 mg/ml of 1-beta-d-arabinofuranosylcytosine, 5% chick embryo extract, 1% horse serum (average 9% fused nuclei), or 1% FCS (2% fused nuclei). Actin, myosin, desmin, neural cell adhesion molecule, MyoD1, and myogenin were expressed by canine satellite cells, but expression of major histocompatibility complex class II antigen was not detected. Reverse transcriptase-polymerase chain reaction detected expression of messenger ribonucleic acid for interleukin-6 (IL-6), IL-15, and leukemia inhibitory factor by canine satellite cells. Collectively, these data suggest that isolated canine satellite cells display properties of other types of myogenic cells and may be useful for further study of the regulation of postnatal myogenesis.

Prostaglandin E2 concentrations in naturally occurring canine cancer.

The purpose of this study was to determine the PGE2 concentration in naturally-occurring cancer in pet dogs and in canine cancer cell lines in order to identify specific types of canine cancer with high PGE2 production which could serve as preclinical models to evaluate anticancer strategies targeting PGE2. PGE2 concentrations were measured by enzyme immunoassay in canine melanoma, soft tissue sarcoma, transitional cell carcinoma, osteosarcoma, and prostatic carcinoma cell lines; in 80 canine tumor tissue samples including oral melanoma (MEL), oral squamous cell carcinoma (SCC), transitional cell carcinoma of the urinary bladder (TCC), lymphoma (LSA), mammary carcinoma (MCA), osteosarcoma (OSA), prostatic carcinoma (PCA); and in corresponding normal organ tissues. High concentrations of PGE(2)(range 400-3300 pg/10(4)cells) were present in cell culture medium from the transitional cell carcinoma, prostatic carcinoma, and osteosarcoma cell lines. PGE2 concentrations in tumor tissues were elevated (tumor PGE2 concentration>mean+2X sd PGE(2)concentration of normal organ tissue) in 21/22 TCC, 5/6 PCA, 7/10 SCC, 5/10 MEL, 3/8 MCA, 4/15 OSA, and 0/9 LSA. Results of this study will help guide future investigations of anticancer therapies that target cyclooxygenase and PGE2.

Vitamin E and macrophage cyclooxygenase regulation in the aged.

Aging is associated with increased evidence of cardiovascular disease (CVD). Atherosclerosis, a major cause of CVD, is an inflammatory process whose development is influenced by several proinflammatory mediators. Products of arachidonic acid metabolism, in particular, prostaglandin (PG) E(2) and thromboxane (TX) A(2), play an important role in the development of atherosclerosis. We showed previously that the aged have higher PGE(2) production compared with their young counterparts. This age-associated increase in PGE(2) production is mainly a consequence of increased cyclooxygenase (COX) activity. We demonstrated further that increased COX activity in old mice is due to the increased expression of mRNA and protein for the inducible form of COX, COX-2. Vitamin E has been shown to reduce PGE(2) production and risk of CVD. In aged mice, we showed that a vitamin E-induced decrease in PGE(2) production is due to decreased COX activity. However, vitamin E had no effect on COX mRNA and protein levels, indicating a post-translational regulation of COX by vitamin E. Further experiments indicated that vitamin E decreases COX activity through reducing formation of peroxynitrite, a hydroperoxide shown to be involved in the activation of COX-2. Other homologues of tocopherols were also effective in inhibiting COX activity, but their degree of inhibition varied. The varied potency to inhibit COX activity was not explained totally by differences in their antioxidant capacity. Vitamin E-induced inhibition of COX activity might contribute to its effect of reducing CVD risk.

Effect of dietary supplements containing antioxidants on attenuation of muscle damage in exercising sled dogs.

OBJECTIVE: To determine whether dietary antioxidants would attenuate exercise-induced increases in plasma creatine kinase (CK) activity in sled dogs. ANIMALS: 41 trained adult sled dogs. PROCEDURE: Dogs, randomly assigned to 2 groups, received the same base diet throughout the study. After 8 weeks on that diet, 1 group (21 dogs) received a daily supplement containing vitamins E (457 U) and C (706 mg) and beta-carotene (5.1 mg), and a control group (20 dogs) received a supplement containing minimal amounts of antioxidants. After 3 weeks, both groups performed identical endurance exercise on each of 3 days. Blood samples were collected before and 3 weeks after addition of supplements and after each day of exercise. Plasma was analyzed for vitamins E and C, retinol, uric acid, triglyceride, and cholesterol concentrations, total antioxidant status (TAS), and CK activity. RESULTS: Feeding supplements containing antioxidants caused a significant increase in vitamin E concentration but did not change retinol or vitamin C concentrations orTAS. Exercise caused significantly higher CK activity, but did not cause a significant difference in CK activity between groups. Exercise was associated with significantly lower vitamin E, retinol, and cholesterol concentrations and TAS but significantly higher vitamin C, triglyceride, and uric acid concentrations in both groups. CONCLUSIONS AND CLINICAL RELEVANCE: Use of supplements containing the doses of antioxidants used here failed to attenuate exercise-induced increases in CK activity. Muscle damage in sled dogs, as measured by plasma CK activity, may be caused by a mechanism other than oxidant stress.

Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs.

OBJECTIVES: To determine effects of dietary antioxidant supplementation on plasma concentrations of antioxidants, exercise-induced oxidative damage, and resistance to oxidative damage during exercise in Alaskan sled dogs. ANIMALS: 62 Alaskan sled dogs. PROCEDURE: Dogs were matched for age, sex, and ability and assigned to 1 of 3 groups: sedentary and nonsupplemented (control [C]; n = 21), exercised and supplemented (S; 22), and exercised and nonsupplemented (N; 19). Dogs in group S were given 400 units of alpha-tocopherol acetate, 3 mg of beta-carotene, and 20 mg of lutein orally per day for 1 month, then dogs in groups S and N completed 3 days of exercise. Blood samples were collected before and after 1 and 3 days of exercise and after 3 days of rest. Plasma antioxidant concentrations were determined, and oxidative damage to DNA (plasma 7,8 dihydro-8-oxo-2'deoxyguanosine [8-oxodG] concentration) and membrane lipids (plasma hydroperoxide concentration) and resistance of plasma lipoproteins to oxidation were assessed. RESULTS: Supplementation increased plasma concentrations of alpha-tocopherol, beta-carotene, and lutein. Plasma concentration of alpha-tocopherol increased and concentration of lutein decreased in group S with exercise. Concentration of 8-oxodG decreased in group S but increased in group N during and after exercise. Lag time of in vitro oxidation of lipoprotein particles increased with exercise in group S only. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary supplementation with antioxidants resulted in increased plasma concentrations of antioxidants. Moreover, supplementation decreased DNA oxidation and increased resistance of lipoprotein particles to in vitro oxidation. Antioxidant supplementation of sled dogs may attenuate exercise-induced oxidative damage.

Dietary beta-carotene stimulates cell-mediated and humoral immune response in dogs.

The role of beta-carotene on immune response in domestic dogs is not known. Female Beagle dogs were fed 0, 2, 20 or 50 mg beta-carotene/d; blood was sampled at wk 0, 1, 2, 4 and 8 for analysis of the following: lymphoproliferation, leukocyte subpopulations and concentrations of interleukin-2 (IL-2), immunoglobulin (Ig)G and IgM. Delayed-type hypersensitivity (DTH) response was assessed at wk 0, 3 and 7. beta-Carotene supplementation increased plasma beta-carotene concentrations in a dose-dependent manner. Compared with unsupplemented dogs, those fed 20 or 50 mg of beta-carotene had higher CD4+ cell numbers and CD4:CD8 ratio. However, there was no treatment difference in CD8+, CD21+ and major histocompatability complex (MHC) class II+ cells. Plasma IgG, but not IgM concentration was higher in dogs fed beta-carotene throughout the study period. The DTH response to phytohemagglutinin (PHA) and vaccine was heightened in beta-carotene-supplemented dogs. beta-Carotene feeding did not influence mitogen-induced lymphocyte proliferation or IL-2 production. Immune response was impaired in dogs classified as low beta-carotene absorbers compared with similar dogs fed the same amount of beta-carotene. Therefore, dietary beta-carotene heightened cell-mediated and humoral immune responses in dogs.

Diffuse calcinosis cutis in a patient with congenital leukemia and leukemia cutis.

We report an unusual case of congenital leukemia with leukemia cutis (LC) and diffuse calcinosis cutis. A newborn girl presented with widespread dusky red and yellowish cutaneous nodules and papules. Bone marrow morphology was consistent with the diagnosis of acute monocytic leukemia of the FAB M5 type. Skin biopsy specimens confirmed the presence of a leukemic infiltrate and revealed calcium salt deposition in the papillary and reticular dermis. Calcinosis was diffuse in the whole skin but spared other organs. Vascular calcification was not present. Serum calcium levels oscillated between 2.5 and 2.86 mmol/l, and phosphorus, parathyroid hormone and 25-hydroxyvitamin D(3) levels were normal. There were diffuse osteoporosis and spontaneous fractures of small tubular bones. The patient responded to chemotherapy but, following consolidation treatment, developed sepsis and died at 120 days of age. Congenital leukemia is rare and LC is uncommon. Hypercalcemia may be a complication of leukemia, which leads to multiorgan metastatic calcification. Despite the absence of frank hypercalcemia, the presence of bone lesions suggests that the patient's calcinosis cutis was of the metastatic type. However, the cutaneous leukemic infiltrate may also represent a triggering factor for calcium deposition in the skin.

Antioxidant modulation of cytokines and their biologic function in the aged.

The oxidant/antioxidant balance is an important determinant of immune cell function, including maintaining integrity and functionality of membrane lipids, cellular proteins, nucleic acids, and for control of signal transduction and gene expression in immune cells. Optimal levels of antioxidants are needed for maintenance of the immune response across all age groups. This need might be more critical, however, in the aged. Age-associated dysregulation of immune response, particularly of cytokine production and T-cell-mediated function, is well documented. The well-known age-related increase in free radical formation and lipid peroxidation contributes, at least in part, to this phenomenon. This review will summarize animal and human studies undertaken by the authors as well as those by other investigators on the effect of antioxidants, vitamin E, beta-carotene, and glutathione on cytokine production and T-cell-mediated function in the aged.

Clinical presentation and outcome of tuberculosis in kidney, liver, and heart transplant recipients in Spain. Spanish Transplantation Infection Study Group, GESITRA.

BACKGROUND: Tuberculosis is unusual in transplant recipients. The incidence, clinical manifestations, and optimal treatment of this disease in this population has not been adequately defined. The present study was undertaken to assess the incidence, clinical features, and response to therapy of Mycobacterium tuberculosis infection in solid-organ transplant recipients. METHODS: We evaluated retrospectively the incidence, clinical characteristics, diagnostic procedures, antituberculous treatment, clinical course, and factors influencing mortality in 51 solid-organ transplant recipients who developed tuberculosis after transplantation. We also reviewed the world literature on tuberculosis in solid-organ transplantation. RESULTS: The overall incidence of tuberculosis was 0.8%. The localization was pulmonary in 63% of the cases, disseminated in 25%, and extrapulmonary in 12%. Tuberculosis developed from 15 days to 13 years after surgery (mean, 23 months). In one third of the cases, diagnosis was not suspected initially, and in three cases, diagnosis was made at necropsy. Fever was the most frequent symptom, followed by constitutional symptoms, cough, respiratory insufficiency, and pleuritic pain. Fifteen patients (33%) developed hepatotoxicity during treatment; hepatotoxicity was severe in seven cases. Hepatotoxicity was higher in patients receiving four or more antituberculous drugs (50%) than in patients receiving three drugs (21%; P=0.03). Serum levels of cyclosporine decreased in the 26 patients under the simultaneous use of rifampin. Nine of them (35%) developed acute rejection, and five (56%) died, in comparison with 3 of 17 patients (18%) who did not develop rejection after the use of cyclosporine and rifampin (P=0.03). Although microbiological response was favorable in 94% of the 35 patients who completed 6 or more months of treatment, 16 other patients (31%) died before diagnosis or in the course of treatment. None of the patients treated for more than 9 months died as a consequence of tuberculosis, whereas the mortality rate was 33% among those treated for 6 to 9 months (P=0.03). Use of antilymphocyte antibodies or high doses of steroids for acute rejection before tuberculosis was associated with a higher mortality rate. CONCLUSIONS: M tuberculosis causes serious and potentially life-threatening disease in solid-organ transplant recipients. Treatment with at least three drugs during 9 months or more, avoiding the use of rifampin, appears to be appropriate.

Epidemiology of gastric cancer.

The incidence of gastric cancer varies widely by country and population, with higher rates among the lower socioeconomic groups. Although the most common cause of cancer death in the United States in 1930, its incidence has decreased dramatically during the past 60 years. Most populations show a 2-1 ratio for male to female gastric cancer cases, and a higher incidence rate among United States blacks than whites. Although rates have generally decreased, there has been a dramatic increase in the incidence of gastric cancer in the cardia. Diet has been the most studied risk factor for gastric cancer. Of particular interest have been N-nitroso compounds derived from the consumption of preserved, smoked, and cured foods. An inverse association with the consumption of fruits and vegetables has also been consistently demonstrated, though the specific nutrient(s) that this represents has been unclear, although ascorbate and beta-carotene have been intensively studied. Among nondietary factors, substantial evidence has accumulated for an increased risk with Helicobacter pylori infection. Other exposures which have been fairly consistently associated with gastric cancer include cigarette smoking, partial gastrectomy, radiation exposure, family history, pernicious anemia, blood group A, certain occupational exposures, and Epstein-Barr virus.

Antioxidants and immune response in aged persons: overview of present evidence.

The oxidant-antioxidant balance is an important determinant of immune cell function, including maintaining the integrity and functionality of membrane lipids, cellular proteins, and nucleic acids and controlling signal transduction and gene expression in immune cells. Optimal amounts of antioxidants are needed for maintenance of the immune response across all age groups. This need might be more critical, however, in aged persons. Age-associated dysregulation of immune response, particularly of T cell-mediated function, is well documented. The well-known age-related increase in free radical formation and lipid peroxidation contributes, at least in part, to this phenomenon. We summarize animal and human studies undertaken by ourselves as well as other investigators on the effects of antioxidants, vitamin E, beta-carotene, and glutathione on the immune response of aged persons. The underlying mechanisms for the antioxidant nutrients' effects as well as their health implications for aged persons are discussed.

Vitamin E and aging immune response.

Aging is associated with decline in immune response, which contributes to increased incidence of infectious and neoplastic diseases. This article summarizes animal and human studies demonstrating the immuno-stimulatory effects of vitamin E for the immune response in aging. The mechanisms of the effect of vitamin E are discussed.

[Corynebacterium urealyticum in kidney transplant patients]. / Corynebacterium urealyticum en pacientes con transplante renal.

BACKGROUND: Corynebacterium urealyticum may produce severe urinary tract infections (UTI) in patients with renal transplantation (RT). The aim of this study was to define the prevalence, clinical spectrum and risk factors for the development of symptomatic UTI in RT receptors with bacteriuria by C. urealyticum. METHODS: The clinical data of RT patients with bacteriuria by C. urealyticum diagnosed in the Hospital Doce de Octubre in Madrid from January 1990 to September 1993 were retrospectively reviewed. The patients corresponded to two clearly differentiated periods. In the first, the presence of C. urealyticum was not actively sought in the urine sample while in the second an intentional search was carried out in all the RT with a selective culture medium containing different antibiotics, Tween-80 and urea to facilitate C. urealyticum identification and growth. RESULTS: C. urealyticum was isolated in the urine of 46 patients (14% of the RT performed in the study period). In the first phase 16 cases were diagnosed with 30 being found in the second with the selective medium. Bacteriuria by C. urealyticum was symptomatic in 18 patients (39%): 12 acute cystitis, one encrusted cystitis (IC), and 5 encrusted pyelitis (IP). Of the symptomatic patients 39% had a history of prolonged vesical catheterization, 27% carried ureteral catheterization and 50% had undergone other urologic manipulations. The clinical consequences were important with development of obstructive uropathy and alteration in renal function (28%), need for surgery (33%) and graft loss (5.5%). All the C. urealyticum strains were sensitive to vancomycin and teicoplanin which were useful in the treatment although the most severe cases (IC, IP) required surgery. CONCLUSIONS: The prevalence of UTI by Corynebacterium urealyticum is high in RT patients. Occasionally, these infections may have severe consequences, particularly in patients with a history of urologic manipulation, if early diagnosis is not performed and adequate antibiotic treatment given. A selective culture medium should be used to isolate C. urealyticum in RT patients.

In vitro glutathione supplementation enhances interleukin-2 production and mitogenic response of peripheral blood mononuclear cells from young and old subjects.

The effect of in vitro glutathione (GSH) supplementation on mitogenic response, interleukin-1, interleukin-2 and prostaglandin E2 production, and cellular GSH level in peripheral blood mononuclear cells (PBMC) from healthy young and old human subjects was studied. In vitro addition of GSH increased cellular GSH level (P < 0.001). Glutathione supplementation at concentrations between 2 to 10 mmol/L enhanced lymphocyte proliferation but at low concentrations (0.5 and 1 mmol/L) decreased mitogenic response. Glutathione-induced enhancement of lymphocyte proliferation due to phytohemagglutinin or concanavalin A was greater in the PBMC from old subjects than in those from young subjects. At optimal concentration (5 mmol), GSH increased interleukin-2 production (P < 0.05) and decreased prostaglandin E2 and leukotriene B4 production (P < 0.01) in both age groups. Furthermore, decreased PBMC mitogenic response by in vitro addition of prostaglandin E2 was reversed by GSH supplementation. Glutathione did not have an effect on interleukin-1 production by PBMC from young subjects; however, GSH supplementation tended (P = 0.08) to increase interleukin-1 production by PBMC from old subjects. We conclude that GSH supplementation enhances T cell-mediated mitogenic response in young and old subjects. This effect is due at least in part to decreased eicosanoid production.

Transferrin and lactoferrin undergo proteolytic cleavage in the Pseudomonas aeruginosa-infected lungs of patients with cystic fibrosis.

Bacterium- and neutrophil-derived proteases have been suggested to contribute to tissue injury at sites of Pseudomonas aeruginosa infection. Pseudomonas elastase cleavage of transferrin enhances in vitro iron removal from this protein by the P. aeruginosa siderophore pyoverdin. This cleavage also generates new iron chelates which, in contrast to iron bound to transferrin, are able to catalyze formation of the highly cytotoxic hydroxyl radical from neutrophil-derived superoxide and hydrogen peroxide via the Haber-Weiss reaction. In order to determine whether this cleavage occurs in vivo, a chemiluminescence immunoblot system was developed to detect the presence of proteolysis products of transferrin or the related iron-binding protein, lactoferrin. Using this immunoblot system, we detected transferrin and lactoferrin cleavage products in bronchoalveolar lavage (BAL) samples from 21 of 22 and 20 of 21 cystic fibrosis (CF) patients, respectively. Three of eleven and two of nine BAL samples from individuals with other forms of chronic inflammatory lung disease had transferrin and lactoferrin cleavage products, respectively. Each patient in whom such products were detected was also infected with P. aeruginosa. No such products were detected in normal individuals. In the CF patients, there was no clear correlation between the extent of transferrin or lactoferrin cleavage and BAL neutrophil or P. aeruginosa concentration or the disease status of the patient. In contrast, in the non-CF patients with chronic inflammatory lung disease, transferrin and lactoferrin cleavage products were detected only in those BAL samples which contained the greatest concentration of both neutrophils and P. aeruginosa. These data provide evidence that P. aeruginosa- and/or human-derived protease cleavage of transferrin and lactoferrin occurs in vivo in the airways of individuals with CF and other forms of chronic lung disease, suggesting that this process could contribute to P. aeruginosa-associated lung injury in these patients.

Iron sequestration by macrophages decreases the potential for extracellular hydroxyl radical formation.

Alveolar macrophages (AM) from smokers contain a much higher quantity of intracellular iron than AM from nonsmokers. Since some forms of iron will catalyze the formation of hydroxyl radical (.OH) from superoxide and hydrogen peroxide, the ability of AM derived from smokers and nonsmokers to generate .OH was assessed. No detectable .OH was produced by AM from either source, suggesting that iron sequestration by AM may limit the potential for .OH-mediated lung injury. Consistent with this hypothesis, the ability of bronchoalveolar lavage fluid (BAL) from smokers and nonsmokers to act as an .OH catalyst decreased after exposure to AM. We found that, like AM, human monocyte-derived macrophages (MDM) have the ability to acquire large quantities of iron from small low molecular weight iron chelates as well as decrease the ability of BAL to act as a .OH catalyst. When MDM or AM were exposed to the iron chelates or BAL they were then able to generate .OH after phorbol myristate acetate stimulation. However, when acutely iron-loaded or BAL-exposed MDM were placed in culture, their ability to produce .OH decreased with time to the level of non-iron-exposed controls. This process correlated with iron translocation from the plasma membrane to the cytosol as well as a 3-9-fold increase in cellular ferritin. No increase in antioxidant enzyme levels or induction of the heat shock response was observed. Iron sequestration by macrophages may protect nearby cells from exposure to potentially cytotoxic iron-catalyzed oxidants such as .OH.