Effect of S-nitrosothiols on cellular glutathione and reactive protein sulfhydryls

S-Nitrosothiols may cause many of the biological effects of NO and cellular effects have been attributed to S-nitrosylation of reactive protein sulfhydryls. This report examines the effect of S-nitrosothiols on the low-molecular-weight thiols and protein thiols in NIH/3T3 cells. A low concentration of S-nitrosocysteine increased the cysteine content of the cells, with no evidence of either low-molecular-weight thiol or protein S-nitrosylation. Millimolar amounts of S-nitrosocysteine produced S-nitrosoglutathione (GSNO), cysteinyl glutathione, cysteine, and glutathione disulfide. Large amounts of protein S-nitrosylation and lesser amounts of protein S-glutathiolation and S-cysteylation were also observed. GSNO and S-nitroso-N-acetylpenicillamine (SNAP) were much less effective than S-nitrosocysteine, but a combination of cysteine and GSNO produced S-nitrosocysteine-like effects. In cultured hepatocytes, millimolar S-nitrosocysteine was significantly less effective since the cells contained three times more glutathione than NIH/3T3 cells. Results suggest that S-nitrosocysteine enters cells intact, and low concentrations do not significantly increase cellular pools of S-nitrosothiol or S-nitrosylated protein. Millimolar concentrations of S-nitrosocysteine generate S-nitrosylated, S-glutathiolated, and S-cysteylated proteins, as well as a variety of low-molecular-weight disulfides and S-nitrosothiols.

Crystal structure of S-glutathiolated carbonic anhydrase III

S-Glutathiolation of carbonic anhydrase III (CAIII) occurs rapidly in hepatocytes under oxidative stress. The crystal structure of the S-glutathiolated CAIII from rat liver reveals covalent adducts on cysteines 183 and 188. Electrostatic charge and steric contacts at each modification site inversely correlate with the relative rates of reactivity of these cysteines toward glutathione (GSH). Diffuse electron density associated with the GSH adducts suggests a lack of preferred bonding interactions between CAIII and the glutathionyl moieties. Hence, the GSH adducts are available for binding by a protein capable of reducing this mixed disulfide. These properties are consistent with the participation of CAIII in the protection/recovery from the damaging effects of oxidative agents.

p53 protein oxidation in cultured cells in response to pyrrolidine dithiocarbamate: a novel method for relating the amount of p53 oxidation in vivo to the regulation of p53-responsive genes

A novel method was developed to determine the oxidation status of proteins in cultured cells. Methoxy-polyethylene glycol-maleimide MW 2000 (MAL-PEG) was used to covalently tag p53 protein that was oxidized at cysteine residues in cultured cells. Treatment of MCF7 breast cancer cells with pyrrolidine dithiocarbamate (PDTC), a metal chelator, resulted in a minimum of 25% oxidation of p53. The oxidized p53 had an average of one cysteine residue oxidized per p53 protein molecule. The effect of PDTC treatment on downstream components of the p53 signal-transduction pathway was tested. PDTC treatment prevented actinomycin D-mediated up-regulation of two p53 effector gene products, murine double minute clone 2 oncoprotein and p21(WAF1/CIP1) (where WAF1 corresponds to wild-type p53-activated fragment 1 and CIP1 corresponds to cyclin-dependent kinase-interacting protein 1). Actinomycin D treatment led to accumulation of p53 protein in the nucleus. However, when cells were simultaneously treated with PDTC and actinomycin D, p53 accumulated in both the nucleus and the cytoplasm. The data indicate that an average of one cysteine residue per p53 protein molecule is highly sensitive to oxidation and that p53 can be efficiently oxidized by PDTC in cultured cells. PDTC-mediated oxidation of p53 correlates with altered p53 subcellular localization and reduced activation of p53 downstream effector genes. The novel method for detecting protein oxidation detailed in the present study may be used to determine the oxidation status of specific proteins in cells.

Surface expression of O-specific lipopolysaccharide in Escherichia coli requires the function of the TolA protein

We investigated the involvement of Tol proteins in the surface expression of lipopolysaccharide (LPS). tolQ, -R, -A and -B mutants of Escherichia coli K-12, which do not form a complete LPS-containing O antigen, were transformed with the O7+ cosmid pJHCV32. The tolA and tolQ mutants showed reduced O7 LPS expression compared with the respective isogenic parent strains. No changes in O7 LPS expression were found in the other tol mutants. The O7-deficient phenotype in the tolQ and tolA mutants was complemented with a plasmid encoding the tolQRA operon, but not with a similar plasmid containing a frameshift mutation inactivating tolA. Therefore, the reduction in O7 LPS was attributed to the lack of a functional tolA gene, caused either by a direct mutation of this gene or by a polar effect on tolA gene expression exerted by the tolQ mutation. Reduced surface expression of O7 LPS was not caused by changes in lipid A-core structure or downregulation of the O7 LPS promoter. However, an abnormal accumulation of radiolabelled mannose was detected in the plasma membrane. As mannose is a sugar unique to the O7 subunit, this result suggested the presence of accumulated O7 LPS biosynthesis intermediates. Attempts to construct a tolA mutant in the E. coli O7 wild-type strain VW187 were unsuccessful, suggesting that this mutation is lethal. In contrast, a polar tolQ mutation affecting tolA expression in VW187 caused slow growth rate and serum sensitivity in addition to reduced O7 LPS production. VW187 tolQ cells showed an elongated morphology and became permeable to the membrane-impermeable dye propidium iodide. All these phenotypes were corrected upon complementation with cloned tol genes but were not restored by complementation with the tolQRA operon containing the frameshift mutation in tolA. Our results demonstrate that the TolA protein plays a critical role in the surface expression of O antigen subunits by an as yet uncharacterized involvement in the processing of O antigen.

Controlling substitution chemistry in ruthenium(II) systems. Synthesis of heteroleptic complexes incorporating the [Ru([9]aneS3)]2+ metal center

The complex [Ru(py)3([9]aneS3)][PF6]2, 1 (py = pyridine), has proved to be a suitable starting material for the synthesis of heteroleptic Ru(II) complexes. By exploiting unfavorable steric interactions between 2-H and 6-H hydrogens of coordinated pyridyl ligands, we have synthesized half-sandwich complexes incorporating the thiocrown [9]aneS3 and a variety of facially coordinated N-donor ligands. Such complexes are easily prepared: Stirring 1 at room temperature in the presence of a suitable nitrile ligand leads to the exclusive substitution of one py ligand to produce complexes such as [([9]aneS3)Ru(py)2(NCMe)][PF6]2, 2. However, if the same reaction is carried out at higher temperatures, two py ligands are substituted, leading to complexes such as [([9]aneS3)Ru(py)(NCMe)2][PF6]2, 3. An alternative approach to such heteroleptic species has also been developed which exploits the restricted ability of thioethers to neutralize positive charges through sigma-donation. This phenomenon allows the synthesis of heteroleptic complexes in a two-step procedure via monocationic species. By variation of the donor/acceptor properties of ligands incorporated into the [Ru([9]aneS3)]2+ metal center, it is possible to tune the Ru(III)/Ru(II) redox couple over a range of > 700 mV. The solid-state structures of 1-3 were confirmed by X-ray crystallography studies. Crystal data: C22H30F12N4O2P2RuS3 (1.CH3NO2), monoclinic, Cc, a = 23.267(5) A, b = 11.5457(18) A, c = 26.192(5) A, alpha = 90 degrees, beta = 114.836(10) degrees, gamma = 90 degrees, Z = 8; C18H25F12N3P2RuS3 (2), triclinic, P1, a = 11.3958(19) A, b = 11.4280(19) A, c = 11.930(2) A, alpha = 100.518(3) degrees, beta = 100.542(3) degrees, gamma = 112,493(3) degrees, Z = 2; C15H23F12N3P2RuS3 (3), orthorhombic, Pna2(1)), a = 14.748(5) A, b = 18.037(18) A, c = 10.341(5) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 4.

Polymorphic growth rates in myrmecophilous insects

A polymorphism in growth rates was recently described affecting the larval development of the myrmecophilous butterfly Maculinea rebeli, spanning different years in a single insect population. The close integration of M. rebeli into the host ant colonies, facilitated by adaptations in behaviour and chemical mimicry, make extended larval development a successful strategy. Here we present additional data for M. rebeli and new data for Maculinea alcon (another cuckoo-feeding lycaenid) and the two myrmecophilous predators Maculinea arion and Microdon mutabilis (Diptera: Syrphidae). As predicted, M. alcon shows the same growth pattern as M. rebeli with a proportion of caterpillars developing in one year and the remainder over two years. This pattern holds in both northern and southern European populations, where M. alcon exploits different species of host. Against expectation, the same bimodal distribution of pre-pupation body weights, indicating one and two year developers, was found for the larvae of M. arion and M. mutabilis. As predators, both species are less closely integrated in their host ant colonies, suggesting that the polymorphism in growth rates is a more general adaptation to a myrmecophilous life style, arrived at by convergent evolution between the Maculinea and Microdon species. For predatory species we suggest that biennialism is an adaptation to the migratory behaviour of the host made possible by the predators' ability to fast over extended periods. We also hypothesize that M. arion represents an ancestral strategy in Maculinea butterflies and that the growth polymorphism might have become genetically fixed in the cuckoo-feeding species.

IL-1 receptor-associated kinase modulates host responsiveness to endotoxin

Endotoxin triggers many of the inflammatory, hemodynamic, and hematological derangements of Gram-negative septic shock. Recent genetic studies in mice have identified the Toll-like receptor 4 as the transmembrane endotoxin signal transducer. The IL-1 intracellular signaling pathway has been implicated in Toll-like receptor signal transduction. LPS-induced activation of the IL-1 receptor-associated kinase (IRAK), and the influence of IRAK on intracellular signaling and cellular responses to endotoxin has not been explored in relevant innate immune cells. We demonstrate that LPS activates IRAK in murine macrophages. IRAK-deficient macrophages, in contrast, are resistant to LPS. Deletion of IRAK disrupts several endotoxin-triggered signaling cascades. Furthermore, macrophages lacking IRAK exhibit impaired LPS-stimulated TNF-alpha production, and IRAK-deficient mice withstand the lethal effects of LPS. These findings, coupled with the critical role for IRAK in IL-1 and IL-18 signal transduction, demonstrate the importance of this kinase and the IL-1/Toll signaling cassette in sensing and responding to Gram-negative infection.

Risk of lymphoid neoplasia after cardiothoracic transplantation. a cohort study of the relation to Epstein-Barr virus

BACKGROUND

Organ transplantation is associated with a greatly increased risk of Epstein-Barr virus (EBV)-associated lymphoproliferative disease (LPD), which is often fatal. There has been little epidemiological analysis, however, of the risk factors for LPD in transplant patients and none on whether the risks of non-EBV-associated lymphoid neoplasms are also increased.

METHODS

The risk of lymphoid neoplasia was assessed in a cohort of 1563 patients who underwent cardiothoracic transplantation at Harefield Hospital, UK from 1980 to 1994 and were followed until December 1995. EBV antibody was assessed in the patients before transplantation, and lymphoid neoplasms were assessed for EBV RNA and latent EBV gene expression.

RESULTS

Thirty cases of LPD occurred during follow-up. One lymphoma of unknown EBV status occurred. There were also six cases of EBV-negative non-Hodgkin's lymphoma (EBV-negative NHL), a highly significant excess over expectations from the general population rates of NHL (standardized incidence ratio 10.2 [95% confidence interval, 4.6-22.8]). The risk of LPD was significantly 10-fold raised in individuals who were EBV seronegative before transplantation; independently of this, it decreased steeply with age at transplantation and was greatest in the first year after transplantation. The risk was significantly raised in young seronegative recipients if the donor was older than the recipient. EBV-negative NHL occurred entirely in men 45 years old and older who were EBV seropositive before transplantation, and risk was not related to duration since transplantation.

CONCLUSIONS

The risk factors found for LPD accord with EBV etiology and with greater hazard from primary infection than from reactivation. A second non-Hodgkin's lymphoid neoplasm, not related to EBV, seems also to be a consequence of transplantation and immunosuppression but is unlikely to be due to first infection by a ubiquitous agent. Its etiology and prevention need investigation separately from LPD.

Impaired cytokine signaling in mice lacking the IL-1 receptor-associated kinase

Stimulation of the type 1 IL-1R (IL-1R1) and the IL-18R by their cognate ligands induces recruitment of the IL-1R-associated kinase (IRAK). Activation of IRAK leads in turn to nuclear translocation of NF-kappaB, which directs expression of innate and adaptive immune response genes. To study IRAK function in cytokine signaling, we generated cells and mice lacking the IRAK protein. IRAK-deficient fibroblasts show diminished activation of NF-kappaB when stimulated with IL-1. Immune effector cells without IRAK exhibit a defective IFN-gamma response to costimulation with IL-18. Furthermore, mice lacking the Irak gene demonstrate an attenuated response to injected IL-1. Deletion of Irak, however, does not affect the ability of mice to develop delayed-type hypersensitivity or clear infection with the intracellular parasite, Listeria monocytogenes. These results demonstrate that although IRAK participates in IL-1 and IL-18 signal transduction, residual cytokine responsiveness operates through an IRAK-independent pathway.

Posttransplantation B lymphoblastic leukemia with Burkitt-like features

BACKGROUND

Posttransplantation Epstein-Barr virus-associated lymphoproliferative disease (PTLPD) occurs as a spectrum of disease ranging from benign, polyclonal, localized lymphoid hyperplasia to malignant, monoclonal, disseminated lymphoma, sometimes involving the bone marrow. To our knowledge, PTLPD has not been previously reported to present as acute lymphoblastic leukemia.

METHODS

We report the case of a boy who developed PTLPD in the form of acute lymphoblastic leukemia 6 years after cardiac transplantation. He had greater than 90% bone marrow invasion by Epstein-Barr virus-positive B lymphoblasts with Burkitt-like features and a t(8;14) translocation.

RESULTS

He was successfully treated with combination chemotherapy but unfortunately died, 6 months after completing treatment, from ischemic heart disease.

CONCLUSIONS

B lymphoblastic leukemia may occur as a manifestation of PTLPD and should be included in the classification of these diseases. Bone marrow examination should be an essential part of the investigation of patients suspected of having PTLPD.

Benchmark testing the Digital Imaging Network-Picture Archiving and Communications System proposal of the Department of Defense

The Department of Defense issued a Request for Proposal (RFP) for its next generation Picture Archiving and Communications System in January of 1997. The RFP was titled Digital Imaging Network-Picture Archiving and Communications System (DIN-PACS). Benchmark testing of the proposed vendors' systems occurred during the summer of 1997. This article highlights the methods for test material and test system organization, the major areas tested, and conduct of actual testing. Department of Defense and contract personnel wrote test procedures for benchmark testing based on the important features of the DIN-PACS Request for Proposal. Identical testing was performed with each vendor's system. The Digital Imaging and Communications in Medicine (DICOM) standard images used for the Benchmark Testing included all modalities. The images were verified as being DICOM standard compliant by the Mallinckrodt Institute of Radiology, Electronic Radiology Laboratory. The Johns Hopkins University Applied Physics Laboratory prepared the Unix-based server for the DICOM images and operated it during testing. The server was loaded with the images and shipped to each vendor's facility for on-site testing. The Defense Supply Center, Philadelphia (DSCP), the Department of Defense agency managing the DIN-PACS contract, provided representatives at each vendor site to ensure all tests were performed equitably and without bias. Each vendor's system was evaluated in the following nine major areas: DICOM Compliance; System Storage and Archive of Images; Network Performance; Workstation Performance; Radiology Information System Performance; Composite Health Care System/Health Level 7 communications standard Interface Performance; Teleradiology Performance; Quality Control; and Failover Functionality. These major sections were subdivided into workable test procedures and were then scored. A combined score for each section was compiled from this data. The names of the involved vendors and the scoring for each is contract sensitive and therefore can not be discussed. All of the vendors that underwent the benchmark testing did well. There was no one vendor that was markedly superior or inferior. There was a typical bell shaped curve of abilities. Each vendor had their own strong points and weaknesses. A standardized benchmark protocol and testing system for PACS architectures would be of great value to all agencies planning to purchase a PACS. This added information would assure the purchased system meets the needed functional requirements as outlined by the purchasers PACS Request for Proposal.

The philosophy of benchmark testing a standards-based picture archiving and communications system

The Department of Defense issued its requirements for a Digital Imaging Network-Picture Archiving and Communications System (DIN-PACS) in a Request for Proposals (RFP) to industry in January 1997, with subsequent contracts being awarded in November 1997 to the Agfa Division of Bayer and IBM Global Government Industry. The Government's technical evaluation process consisted of evaluating a written technical proposal as well as conducting a benchmark test of each proposed system at the vendor's test facility. The purpose of benchmark testing was to evaluate the performance of the fully integrated system in a simulated operational environment. The benchmark test procedures and test equipment were developed through a joint effort between the Government, academic institutions, and private consultants. Herein the authors discuss the resources required and the methods used to benchmark test a standards-based PACS.

Diet, micronutrients, and the prostate gland

Diseases of the prostate gland, particularly adenocarcinoma and benign prostatic hyperplasia (BPH), are age-related. Prostate cancer is the most commonly occurring tumor in U.S. men. Differences in the incidence of this disease among ethnic populations are not due solely to genetic differences. Many efforts have been devoted to studying associations between nutrition and prostate cancer. The strongest association appears to be related to total fat intake and increased risk of this malignancy. Evidence also exists to suggest a role for certain micronutrients, such as zinc, selenium, vitamin E, lycopene, phytoestrogens, and phytosterols, although the role of nutrition and micronutrients in protection against prostate cancer is less convincing. Further research is necessary.

S-nitrosylation and S-glutathiolation of protein sulfhydryls by S-nitroso glutathione

The modification of reactive protein sulfhydryls by S-nitrosoglutathione and other NO donors has been studied by gel isoelectric focusing. S-nitrosylated, unmodified, and S-glutathiolated protein forms are differentiated by this method. With specific antibodies for the protein of interest, both S-nitrosylation and S-glutathiolation of the protein were analyzed in mixtures obtained as soluble tissue or cell extracts. The effect of S-nitrosoglutathione (GSNO) on purified phosphorylase b, on carbonic anhydrase III in an extract from rat liver, and on H-ras expressed in Escherichia coli was examined. When fresh GSNO reacted with pure phosphorylase b, only S-nitrosylated forms of the protein were observed. Likewise the NO donors, amyl nitrite, spermine NONOate, and diethylamine NONOate, all generated S-nitrosylated phosphorylase b. When crude mixtures of proteins from rat liver (containing carbonic anhydrase III) or from E. coli (containing an overexpressed form of H-ras) were exposed to fresh GSNO, both the S-nitrosylated and the S-glutathiolated forms of the proteins were observed. It is suggested that reactive intermediates from the breakdown of GSNO are responsible for the observed S-glutathiolation. These experiments show that both S-nitrosylated and S-glutathiolated forms of proteins may be generated by the addition of GSNO to mixtures containing proteins with reactive sulfhydryls. These protein modifications may exhibit metabolic consequences independent of the release of nitric oxide.

Heat shock does not attenuate low-frequency fatigue

Whole-body hyperthermia or heat shock confers protection to myocardial contractility against reperfusion-induced injury. The purpose of this study was to determine whether heat shock could provide similar protection to skeletal muscle contractility against low-frequency fatigue. Male Sprague-Dawley rats (6 rats/group) were heat shocked at 41.5 degrees C for 15 min either 24 h or 4 days prior to fatiguing stimulation to compare the contractile responses of the plantaris muscle with those of a nonheated group. Both 24 h and 4 days after heat shock, the 72-kDa heat shock protein (HSP72) was elevated above control levels. There were no differences between the heat-shocked and non-heat-shocked animals in measures of contractility prior to fatiguing contractions or in resistance to fatigue. Heat-shock preconditioning did not lead to improved postfatigue force recovery above control responses and, in fact, delayed the recovery of force. This study does not support the use of heat-shock therapy to improve skeletal muscle contractile performance under fatiguing conditions.

Heat shock does not attenuate low-frequency fatigue

Whole-body hyperthermia or heat shock confers protection to myocardial contractility against reperfusion-induced injury. The purpose of this study was to determine whether heat shock could provide similar protection to skeletal muscle contractility against low-frequency fatigue. Male Sprague-Dawley rats (6 rats/group) were heat shocked at 41.5°C for 15 min either 24 h or 4 days prior to fatiguing stimulation to compare the contractile responses of the plantaris muscle with those of a nonheated group. Both 24 h and 4 days after heat shock, the 72-kDa heat shock protein (HSP72) was elevated above control levels. There were no differences between the heat-shocked and non-heat-shocked animals in measures of contractility prior to fatiguing contractions or in resistance to fatigue. Heat-shock preconditioning did not lead to improved postfatigue force recovery above control responses and, in fact, delayed the recovery of force. This study does not support the use of heat-shock therapy to improve skeletal muscle contractile performance under fatiguing conditions.Key words: heat shock proteins, rat, skeletal muscle, contractile properties, HSP72.

Resting respiratory tract dendritic cells preferentially stimulate T helper cell type 2 (Th2) responses and require obligatory cytokine signals for induction of Th1 immunity

Consistent with their role in host defense, mature dendritic cells (DCs) from central lymphoid organs preferentially prime for T helper cell type 1 (Th1)-polarized immunity. However, the "default" T helper response at mucosal surfaces demonstrates Th2 polarity, which is reflected in the cytokine profiles of activated T cells from mucosal lymph nodes. This study on rat respiratory tract DCs (RTDCs) provides an explanation for this paradox. We demonstrate that freshly isolated RTDCs are functionally immature as defined in vitro, being surface major histocompatibility complex (MHC) II lo, endocytosishi, and mixed lymphocyte reactionlo, and these cells produce mRNA encoding interleukin (IL)-10. After ovalbumin (OVA)-pulsing and adoptive transfer, freshly isolated RTDCs preferentially stimulated Th2-dependent OVA-specific immunoglobulin (Ig)G1 responses, and antigen-stimulated splenocytes from recipient animals produced IL-4 in vitro. However, preculture with granulocyte/macrophage colony stimulating factor increased their in vivo IgG priming capacity by 2-3 logs, inducing production of both Th1- and Th2-dependent IgG subclasses and high levels of IFN-gamma by antigen-stimulated splenocytes. Associated phenotypic changes included upregulation of surface MHC II and B7 expression and IL-12 p35 mRNA, and downregulation of endocytosis, MHC II processing- associated genes, and IL-10 mRNA expression. Full expression of IL-12 p40 required additional signals, such as tumor necrosis factor alpha or CD40 ligand. These results suggest that the observed Th2 polarity of the resting mucosal immune system may be an inherent property of the resident DC population, and furthermore that mobilization of Th1 immunity relies absolutely on the provision of appropriate microenvironmental costimuli.

Optimal cascade operation of optical phased-array beam deflectors

An optimal strategy for cascading phased-array deflectors is presented that allows for high-resolution random-access beam steering with continuous scan-angle control but requires a minimum number of control lines. The system is analyzed theoretically by use of a Fourier optics approach and then verified experimentally. A pair of 32-channel optical phased arrays fabricated by use of surface electrodes on lanthanum-modified lead zirconate titanate (PLZT) was sandwiched together to form a functional two-stage phased-array cascade. Experimental results from the PLZT-based two-stage deflector are presented that confirm the performance enhancements of the optimized cascading technique. A phase-staggered discrete-offset-bias protocol for controlling the cascaded system is shown to be optimal in terms of maximum diffraction efficiency and minimum number of control lines, while still providing for full analog scan control.

Important drug-nutrient interactions in the elderly

Several drug-nutrient interactions can occur, but their prevalence may be accentuated in the elderly. Geriatric patients may experience age-related changes in the pharmacokinetics of a drug-absorption, distribution, metabolism and excretion. When drug-nutrient interactions occur, they usually affect absorptive processes more frequently. Specific transporter systems facilitate the absorption of many drugs. Little is known about how these transporter systems are affected by aging. Co-existing disease states in the elderly may exaggerate the action of a drug and represent a confounding factor in drug-nutrient interactions. While several different drug-nutrient interactions are important in the elderly, those affecting the cardiovascular system warrant special attention.

Cytoplasmic, nuclear, and platelet autoantibodies in human granulocytic ehrlichiosis patients

Serum samples from patients with confirmed human granulocytic ehrlichiosis (HGE) were tested for cytoplasmic, nuclear, and platelet autoantibodies and rheumatoid factor. The indirect fluorescence antinuclear antibody test on Hep-2 cells demonstrated antinuclear titers of > or = 40 and > or = 160 in 44 and 10%, respectively, of serum samples from HGE patients. Two patients (4%) had anticytoplasmic (mitochondrial and spindle apparatus) antibodies with a titer of 80 and two patients (4%) had anticytoplasmic (mitochondrial) antibodies with a titer of 160 or greater. Flow cytometry was used to demonstrate antiplatelet antibodies in 80% of first serum samples from HGE patients. Rheumatoid factor was not detected. Nuclear and cytoplasmic autoantibodies are a major cause of interference when the indirect fluorescence antibody test is used to detect fluorescence of morulae in Ehrlichia-infected equine neutrophils or HL-60 promyelocytes. Antiplatelet antibodies may contribute to the profound thrombocytopenia which is a characteristic laboratory feature during the acute phase of HGE infection. Whether autoantibodies precede infection or are caused by immune activation of HGE deserves further study.

Reconstitution of EBV-specific T cell immunity in solid organ transplant recipients

EBV-specific autologous CTL were grown in vitro from three adults (two liver transplant recipients and one patient on hemodialysis awaiting kidney retransplant). All CTL lines were TCR alphabeta, CD8 positive cells, EBV specific, and MHC class I restricted. The CTL lines were expanded in vitro and infused in three escalating doses (5 x 10(7), 1 x 10(8), and 2 x 10(8) at monthly intervals. Weekly blood samples were collected following each infusion. EBV-specific CTL precursor cells in peripheral blood were quantitated by limiting dilution analysis, and their effect on EBV load in vivo was assessed by semiquantitative PCR. In all three patients, the numbers of CTL precursor cells increased during the weeks following the infusions and were highest after the third infusion. This level gradually declined but remained above the preinfusion levels for up to 3 mo. EBV genome copy number, on the other hand, dropped following the first infusion and became undetectable thereafter. The EBV DNA level remained lower than the pretransplant level in all patients for up to 3 mo after the last infusion. Our study shows that it is feasible to generate and expand EBV-specific CTL from pretransplant blood samples of solid organ transplant recipients, that these CTL can be stored and infused posttransplant, and that they remain cytotoxic and EBV specific in vivo. The aim of this study is to use these CTL for prevention and treatment of lymphoproliferative disease in solid organ transplant recipients.

Analysis of the T-cell micro-environment in Epstein-Barr virus-related post-transplantation B lymphoproliferative disease

Epstein-Barr virus (EBV) post-transplantation B lymphoproliferative disease (BLPD) may undergo regression after immunosuppression withdrawal and restoration of EBV-specific cytotoxic T-cell (CTL) activity in the immunocompromised allografted host. The presence of morphologically normal T cells in the BLPD micro-environment may influence tumour behaviour in vivo. In this immunopathological study, the phenotype and the number of T cells and other immunoregulatory cells have been investigated in seven primary and four recurrent BLPD biopsies from nine solid organ transplant recipients. BLPD with either viral lymphadenopathic or polymorphic lymphoma appearances was found to contain sizeable T-cell populations, mainly of memory/helper (TCR alpha/beta +, CD3+, CD4+, CD45RO+) type. Cytotoxic (TCR alpha/beta +, CD3, CD8+, Tia-1+) T cells were strikingly low in all samples. Low CD28 and CD25 expression suggested that secondary signals for functional and sustained T-cell activation may be deficient in these tumours. No close correlation was found between the degree of T-cell infiltration and clinical outcome, although appreciably higher number of CD8+ T cells were detected in three BLPD tumours showing prolonged clinical remission after treatment. While some level of EBV-specific T-cell function may be present in untreated BLPD, the overall findings of this study suggest that the nature of T-cell infiltrates may reflect a response to immunosuppressive therapy rather than to EBV infection per se. The possibility that a local EBV-specific T-cell response is generated in BLPD undergoing regression after treatment needs to be investigated.

Effect of cutaneous burn injury and resuscitation on the cerebral circulation in an ovine model

The aim of our study was to evaluate the effects of a large cutaneous burn injury on the cerebral circulation. Anesthetized sheep (n = 8) were prepared with vascular catheters, a urinary catheter and a Richmond bolt for intracranial pressure monitoring. A scald injury was inflicted on 70 percent of total body surface area with hot water. Resuscitation was started 30 min after scald with Ringer's lactate to restore and maintain baseline oxygen delivery. Resuscitation maintained blood pressure, cardiac output and urine output at normal levels. Brain blood flow was measured with colored microspheres. During resuscitation intracranial pressure rose slowly from 10.6 +/- 1.5 to 17.0 +/- 4.0 mmHg (P < 0.05) and cerebral perfusion pressure was reduced from 86.4 +/- 6.8 to 64.1 +/- 2.8 mmHg (P < 0.05). During early resuscitation cerebrovascular resistance declined to maintain brain blood flow and oxygen delivery at baseline or better. After 6 h, mean cerebrovascular resistance was inappropriately increased during a period of reduced cerebral perfusion pressure which resulted in brain blood flow reductions of half the baseline levels. These data suggest that autoregulation maintains brain blood flow immediately after burn shock and early resuscitation, but the autoregulation may be less effective as burn resuscitation proceeds.

Gracile bone dysplasia

Gracile bones are a frequent abnormality associated with fetal hypokinesia of any cause. With the exception of thin, undermineralized bones, the chondro-osseous structure is usually normal in these cases. We present a lethal skeletal dysplasia comprising minor anomalies, central nervous system abnormalities, gracile long bones, and abnormal chondro-osseous morphology. In addition to a short, disordered growth plate, the chondrocytes contained dilated loops of rough endoplasmic reticulum, suggesting an abnormality of an extracellular matrix protein. This protein appears to have effects on chondro-osseous and on facial and central nervous system development. We suggest the term "gracile bone dysplasia" to describe this disorder.

A prospective study in heart and lung transplant recipients correlating persistent Epstein-Barr virus infection with clinical events

BACKGROUND

A 2-year prospective study was set up with 30 cardiothoracic transplant recipients to study Epstein-Barr virus (EBV) infection and immunity and their correlation with clinical events.

METHODS

Regression assays were used to measure EBV-specific cytotoxic T lymphocyte (CTL) function. Tissue culture, immunoblotting, and polymerase chain reaction were used for EBV detection and isolate variation studies.

RESULTS

CTL activity was significantly lower in pretransplant seropositive patients than in healthy controls (P<0.001). CTL response was undetectable in all patients during the first 6 months after transplantation, but returned at levels significantly lower than pretransplant and control levels during the second posttransplant year (P<0.001). Return of CTL function was directly correlated with time of last treated rejection episode (P<0.003) and duration of high plasma levels of cyclosporine (over 400 ng/ml; P<0.003). Significantly higher levels of EBV were detected in peripheral blood during the first 6 months than in pretransplant or control samples (P<0.05). Excretion of EBV in throat washings was significantly lower during the first 3 months when all patients were receiving acyclovir than in pretransplant and control samples (P=0.02). An increase in virus shedding was noted 3-6 months after transplantation, which was significantly higher than in pretransplant patients and controls (P<0.05). Comparison of recipients' and donors' virus isolates in 11 cases showed that seropositive recipients retained their original EBV isolate and did not acquire the donor virus.

CONCLUSIONS

Immunosuppression decreased EBV-specific host immune function, which in turn favored increased EBV load in peripheral blood and increased excretion in the oropharynx. The transfer of donor virus to the seropositive recipients was not observed.

Highlights of the Digital Imaging Network-Picture Archiving and Communications System Project

The Department of Defense issued its requirements for a Digital imaging Network-Picture Archiving and Communications System (DIN-PACS) in a Request for Proposals to industry in January, 1997. The DIN-PACS shall be an open systems network of digital devices designed for the effective acquisition, transmission, display and management of diagnostic imaging studies. This network is primarily based on two international standards, Digital imaging and Communications in Medicine (DICOM) and Health Level 7 (HL7). The DIN-PACS is required to communicate in a bidirectional manner with the Department of Defense standard hospital information system called the Composite Health Care System (CHCS) through an HL7 compliant interface. The DIN-PACS model and its published specifications stress functionality and performance rather than system architecture to allow industry to propose optimal approaches for implementation. This paper discusses the functional requirements of the DIN-PACS in terms of its internal operations as well as its communication with external systems and components. This is a US government work. There are no restrictions on its use.

Successful treatment of severe dysrhythmias in infants with respiratory syncytial virus infections: two cases and a literature review

OBJECTIVES

To describe severe myocardial manifestations in two infants with respiratory syncytial virus infection and to review published literature reporting cardiac involvement in patients with respiratory syncytial virus disease.

DESIGN

Case report and literature review.

SETTING

Tertiary care pediatric intensive care unit (ICU).

PATIENTS

Two infants admitted to the pediatric ICU for dysrhythmias and severe myocardial dysfunction and infected with respiratory syncytial virus.

INTERVENTIONS

Conventional cardiovascular, antidysrhythmic, and respiratory support, as well as extracorporeal membrane oxygenation and high-frequency oscillatory ventilation.

MEASUREMENTS AND MAIN RESULTS

Both patients had respiratory syncytial virus infections and clinical evidence of severe myocarditis, with dysrhythmias, cardiomegaly, and cardiogenic shock. Both infants survived their hospitalizations. To our knowledge, these two patients are the first reported cases of myocarditis in infants with respiratory syncytial virus infection.

CONCLUSIONS

Severe myocardial dysfunction and dysrhythmias may accompany respiratory syncytial virus infection in some infants and may be reversible with aggressive supportive therapy.

Chromosomes 22q11 deletion syndrome: an update and review for the primary pediatrician

Chromosome 22q11 deletion syndrome is a relatively newly described syndrome that encompasses the majority of patients previously felt to have velo-cardio-facial syndrome, DiGeorge syndrome, and conotruncal anomaly face syndrome. The disorder is characterized by a deletion of band 11 on the long arm of chromosome 22 most often recognized by fluorescent in situ hybridization (FISH) techniques. Extensive laboratory investigations are currently ongoing to uncover the specific genes involved and their functions. Phenotypically, individuals present with congenital heart disease, palatal abnormalities, facial dysmorphism, and developmental delay, as well as variable degrees of immunodeficiency, hypocalcemia, and endocrine abnormalities. The primary care physician has an important role in caring for these patients and their families. We review the current state of knowledge regarding chromosome 22q11 deletion syndrome, with an emphasis on the clinical presentation and on prevention and treatment of the known complications associated with this multisystem disorder. Chromosome 22q11 deletion syndrome can be inherited in an autosomal dominant fashion or result from a de novo deletion or translocation. Hence, this syndrome may have significant reproductive risks to affected individuals and families.

Is atelectasis following aortocoronary bypass related to temperature?

OBJECTIVE

To determine the frequency of acute postoperative atelectasis in patients undergoing aortocoronary bypass with either normothermic (warm) or hypothermic (cold) technique.

DESIGN

Prospective, randomized study comparing two groups.

SETTING

University-affiliated hospital.

PATIENTS

Three hundred thirty-one patients (166 cold and 165 warm) undergoing isolated aortocoronary bypass.

MEASUREMENTS

Chest radiographs were obtained preoperatively, on the day of surgery, and subsequently as clinically indicated until discharge from the hospital. Radiologist (blinded to the patient allocation into warm or cold group) scored the atelectasis from 0 to 3 based on its severity. Regression analysis was used to determine if there was any difference in the atelectasis scores between the two groups.

RESULTS

Mean daily postoperative atelectasis scores were not different between the cold and warm groups. The number of patients requiring chest radiographs was similar in both groups. The percent of patients with abnormal chest radiographs was similar in both groups.

CONCLUSION

The temperature of cardioplegia has no effect on the development of atelectasis following aortocoronary bypass, and therefore temperature-related cold injury is not a major cause of atelectasis following this type of surgery.

Steroids inhibit uptake and/or processing but not presentation of antigen by airway dendritic cells

Recent studies from our laboratory indicate that local and (particularly) systemic steroids can modulate the traffic of dendritic cells (DC) through resting and inflamed airway epithelial tissues. The present report focuses upon the T-cell activating properties of DC, which are controlled by granulocyte-macrophage colony-stimulating factor (GM-CSF) signals, and in particular the question of whether the DC-stimulating effects of GM-CSF are susceptible to regulation by steroids. We present evidence that while dexamethasone inhibited GM-CSF-dependent uptake and/or processing of exogenous antigen by DC, it was ineffective in blocking the presentation of preprocessed self antigen to alloreactive T cells in a one-way mixed lymphocyte reaction (MLR). Associated GM-CSF-induced up-regulation of major histocompatability complex (MHC) class II and CTLA4 ligand expression by DC were also unaffected by dexamethasone phosphate (DX), reinforcing the view that the inhibitory effects of steroids on the T-cell activating functions of DC are restricted to steps upstream from presentation of processed antigen to the T-cell receptor (TCR). These findings have potentially important implications in relation to the use of topical steroids in the treatment of atopic asthma, a disease in which local T-cell activation in airway tissue is a key pathogenic factor, and which furthermore is characterized by intense production of GM-CSF within the airway epithelium.

S-glutathiolated hepatocyte proteins and insulin disulfides as substrates for reduction by glutaredoxin, thioredoxin, protein disulfide isomerase, and glutathione

The disulfide-reducing activities of glutaredoxin, thioredoxin, protein disulfide isomerase, glutathione, and cysteine were directly compared with a mixture of hepatocyte 35S-glutathiolated proteins as the substrate. Dethiolation of individual 35S-labeled protein bands from the mixture of hepatocyte proteins was analyzed by SDS-PAGE. All of the 35S-labeled protein bands could be completely dethiolated by glutaredoxin, thioredoxin, protein disulfide isomerase, glutathione, or cysteine. On a molar basis glutaredoxin was over 10 times more effective than either thioredoxin or protein disulfide isomerase. Dethiolation rates of individual proteins varied in minor ways. For example, glutaredoxin dethiolated the 15-, 30-, and 48-kDa protein bands 3 to 4 times faster than the 27-, 28-, and 77-kDa bands. Glutaredoxins from pig liver or from bovine heart had the same specificity and similar activity. The rate of dethiolation by glutathione alone was low compared to the glutaredoxin-catalyzed process, but all 35S-labeled protein bands could be reduced by glutathione, cysteine, or dithiothreitol. Glutathione was clearly more effective than cysteine when these two thiols were compared on the basis of the concentration of thiolate anion available at neutral pH. Therefore, glutathione is a more specific reductant of S-glutathiolated proteins than is cysteine but it is much less effective than glutaredoxin. Since glutaredoxin activity in cells is 10 times higher than the concentration used in these experiments, ample activity is available to account for substantial rates of dethiolation in vivo. Thioredoxin is quite inefficient as a reductant of S-glutathiolated proteins, but it was reasoned that it might first reduce glutaredoxin, which then could reduce the S-glutathiolated protein. A combination of thioredoxin and glutaredoxin was effective. It is proposed that glutaredoxin is the principal agent responsible for protein dethiolation in vivo. The effectiveness of glutaredoxin, thioredoxin, and protein disulfide isomerase as reductants for protein disulfide bonds was examined with insulin as the substrate. Protein disulfide isomerase was very effective and thioredoxin was nearly as effective. Human thioredoxin was similar to Escherichia coli thioredoxin in reactivity and specificity. Glutaredoxin did not facilitate insulin reduction at equal concentrations. Thus, protein disulfide isomerase and thioredoxin are more effective than glutaredoxin as reductants of insulin protein disulfides. The apparent reduction potential of pig liver glutaredoxin (-0.159 +/- 0.004 V) was determined by measuring the amount of reduced glutaredoxin in equilibrium with mixtures of glutathione and glutathione disulfide. Glutaredoxin was a weaker reductant than E. coli thioredoxin (-0.260 V) and was similar to protein disulfide isomerase (-0.11 to -0.19 V). The role of these proteins as disulfide reductants is not determined solely by thermodynamic considerations. A glutathione binding site at the dithiol region of glutaredoxin may be of primary importance for its function in protein dethiolation, while a different specific peptide binding site in thioredoxin may be more suited to certain protein disulfide structures.

beta-mercaptoethanol enhances blastocyst formation rate of bovine in vitro-matured/in vitro-fertilized embryos

The objectives of this research were to determine the effects of beta-mercaptoethanol (beta-ME) and fetal bovine serum (FBS) on in vitro development of bovine embryos derived from oocytes matured and fertilized in vitro and to examine the mechanism through which beta-ME may influence embryo development. A 2 x 2 factorial treatment arrangement was used to evaluate the effect of 0 or 100 microM beta-ME and 0% or 10% FBS on embryos cultured in Medium 199 (M199) in the absence of somatic cells. Embryos were randomly allocated within stage of development (< 8 cells or 8-16 cells) to one of four treatment combinations and were cultured for 6 days. Both beta-ME and FBS promoted increased (p < 0.01) development of embryos to the blastocyst stage, and their effects were greater (p < 0.01) in 8- to 16-cell embryos than in embryos having fewer than 8 cells at the initiation of treatment. The cysteine and cystine content of M199, with and without beta-ME, were determined by HPLC. Medium supplemented with beta-ME contained neither cysteine nor cystine, and it is suggested that these compounds were converted into a mixed disulfide between cysteine and beta-ME. These results indicate that beta-ME is capable of enhancing bovine embryo development in a cell-free, serum-free culture system.

Constitutively active human estrogen receptors containing amino acid substitutions for tyrosine 537 in the receptor protein

To better understand structure-activity relationships in the human estrogen receptor (ER), we examined the role of tyrosine 537 in the transcriptional response of the receptor, since this residue is close to a region of the hormone-binding domain shown previously to be important in hormone-dependent transcriptional activity and because this amino acid has been proposed to be a tyrosine kinase phosphorylation site important in the activity of the ER. We substituted five amino acids at this position (alanine, phenylalanine, glutamic acid, lysine, or serine) and screened these mutants for their biological activities in the presence and absence of estradiol. Two of the ER mutants, Y537A and Y537S, displayed estrogen-independent constitutive activity that was approximately 20% or 100%, respectively, of the activity of the wild type receptor with estradiol, when assessed in two different cell backgrounds using three different estrogen-responsive promoters. In some circumstances, the Y537E and Y537K proteins also exhibited some low level of constitutive activity. The constitutive activity of the mutants, as well as their activity in the presence of E2, was fully suppressed by antiestrogen. The extent of interaction of the constitutively active ERs with the steroid receptor coactivator-1 (SRC-1) closely parallel the magnitude of transcriptional activity of the receptor. Whereas wild type ER showed interaction with SRC-1 only in the presence of estrogen, Y537A and Y537S ER showed moderate or full interaction in the absence of ligand, an interaction that was blocked by antiestrogen, and the magnitude of interaction was increased to or remained at 100% upon estradiol treatment, implying that the ability of an ER to associate with SRC-1 is a good indicator of a transcriptionally active conformational state of the receptor. Our findings indicate that tyrosine 537 is in a region important in the ligand regulation of ER transcriptional activity and that the presence of certain amino acids at this position can shift ER into a conformation that is active even without ligand. However, tyrosine is not required at this site for estrogen binding or transcriptional response to estrogen in the systems investigated. Our findings, interpreted in light of the recently published x-ray crystal structure of the ligand-binding domains of three related receptors of the nuclear receptor superfamily, suggest that some of the amino acid substitutions introduced at position 537 may facilitate the shift of helix 12 of the ER into an active conformation and/or allow for differential stabilization of the receptor in its active form.

Epstein-Barr virus associated Burkitt lymphoma in a heart transplant recipient

This report describes a case of Epstein-Barr [correction of Epstein Barr] Virus related post-transplantation B lymphoproliferative disease of unusual Burkitt lymphoma (BL) type in which combined cytotoxic agents (PACE BOM) successfully produced complete and long-term tumor remission.

Transmission of donor Epstein-Barr virus (EBV) in transplanted organs causes lymphoproliferative disease in EBV-seronegative recipients

Epstein-Barr virus (EBV) is associated with post-transplant lymphoproliferative disease (PTLD). To determine whether the donor EBV isolate is transmitted to the recipient via the allograft and causes PTLD, EBV isolates from four cases of PTLD in cadaveric heart and/or lung transplant recipients were compared with the donor isolates by PCR and DNA sequence analysis. Two recipients who were EBV seronegative at transplantation acquired an EBV isolate indistinguishable from that of the donor and developed PTLD. In contrast, in two patients who were seropositive before transplantation, the donor isolate differed from that present in PTLD of the recipient. The results suggest that the acquisition of donor EBV is a risk factor for PTLD development in a previously seronegative transplant recipient.

Hunter-McAlpine craniosynostosis phenotype associated with skeletal anomalies and interstitial deletion of chromosome 17q

Hunter-McAlpine syndrome is an autosomal dominant disorder consisting of variable manifestations including craniosynostosis, almond-shaped palpebral fissures, small mouth, mild acral-skeletal anomalies, short stature, and mental deficiency. We report on a 9-year-old boy with this phenotype with more severe skeletal abnormalities than previously described. Chromosomes showed del(17)(q23.1-->q24.2); the more severe phenotype may be explained by the deletion. The deletion also suggests the possibility that the gene for Hunter-McAlpine syndrome might map to that region.

Risk assessment of polymyositis/dermatomyositis after treatment with injectable bovine collagen implants

BACKGROUND

Questions have been raised about a possible relation between injectable collagen and polymyositis and dermatomyositis (PM/DM). Predictions of the prevalence of PM/DM have been based on anecdotal estimates of the duration of follow-up for the collagen-treated population.

OBJECTIVE

Our purpose was to study the duration of follow-up for a large sample of collagen-treated patients.

METHODS

Physicians in North America who purchased collagen implants during fiscal year 1988 were categorized according to collagen practice size; one third were randomly invited to participate in the study.

RESULTS

Review of 2622 patient records yielded an average duration of follow-up of 4 years.

CONCLUSION

Five-year incidence rates were used to estimate the expected number of cases of PM/DM in the collagen-treated population. Through June 1993 the expected number was 30.2. The number of confirmed cases after treatment was seven, less than one fourth of the number of cases expected for a model of the collagen-treated population, matched for age, sex, and race.

Protein S-thiolation and dethiolation during the respiratory burst in human monocytes. A reversible post-translational modification with potential for buffering the effects of oxidant stress

Stimulation of the respiratory burst in mouse macrophages or human neutrophils results in the formation of disulfide bonds between low m.w. thiols and sulfhydryl groups on specific cytosolic proteins (S-thiolation). S-thiolation is reversible in certain chemical systems. The aim of the present study was to analyze the dynamic nature of this process in human monocytes under physiologic conditions. We report here that the extent of S-thiolation and the rate of respiratory burst stimulated by opsonized zymosan or phorbol diester increased for 10 to 20 min and then declined (dethiolation) in close association. Individual proteins underwent S-thiolation and dethiolation at different rates. H2O--appeared particularly effective in mediating S-thiolation, based on inhibition of S-thiolation by added catalase and accentuation by azide, which inhibits cellular catalase. S-thiolation did not occur in stimulated monocytes from patients with chronic granulomatous disease. The addition of H2O2 to monocytes or lymphocytes induced rapid S-thiolation (1 to 3 min); a subsequent dethiolation returned most of the proteins to baseline by 15 to 30 min. At 0 degrees C and after addition of 1,3-bis-(2-chloroethyl)-1-nitrosourea, there was effective S-thiolation on exposure to H2O2, but dethiolation was inhibited, suggesting a possible role for glutathione (GSH)/thioredoxin reductase systems in this process. GSH was determined to be the most abundant low m.w. thiol bound to S-thiolated proteins, but gamma-glutamylcysteine and cysteine were also bound. The time of maximal reduction in cytosolic GSH during the respiratory burst (10 min) coincided with the time at which protein-bound GSH was highest. S-thiolation-dethiolation represents a reversible post-translational modification that could protect cellular proteins from irreversible oxidative damage.

Protein S-thiolation and dethiolation during the respiratory burst in human monocytes. A reversible post-translational modification with potential for buffering the effects of oxidant stress

Stimulation of the respiratory burst in mouse macrophages or human neutrophils results in the formation of disulfide bonds between low m.w. thiols and sulfhydryl groups on specific cytosolic proteins (S-thiolation). S-thiolation is reversible in certain chemical systems. The aim of the present study was to analyze the dynamic nature of this process in human monocytes under physiologic conditions. We report here that the extent of S-thiolation and the rate of respiratory burst stimulated by opsonized zymosan or phorbol diester increased for 10 to 20 min and then declined (dethiolation) in close association. Individual proteins underwent S-thiolation and dethiolation at different rates. H2O--appeared particularly effective in mediating S-thiolation, based on inhibition of S-thiolation by added catalase and accentuation by azide, which inhibits cellular catalase. S-thiolation did not occur in stimulated monocytes from patients with chronic granulomatous disease. The addition of H2O2 to monocytes or lymphocytes induced rapid S-thiolation (1 to 3 min); a subsequent dethiolation returned most of the proteins to baseline by 15 to 30 min. At 0 degrees C and after addition of 1,3-bis-(2-chloroethyl)-1-nitrosourea, there was effective S-thiolation on exposure to H2O2, but dethiolation was inhibited, suggesting a possible role for glutathione (GSH)/thioredoxin reductase systems in this process. GSH was determined to be the most abundant low m.w. thiol bound to S-thiolated proteins, but gamma-glutamylcysteine and cysteine were also bound. The time of maximal reduction in cytosolic GSH during the respiratory burst (10 min) coincided with the time at which protein-bound GSH was highest. S-thiolation-dethiolation represents a reversible post-translational modification that could protect cellular proteins from irreversible oxidative damage.