Non-thermalization in trapped atomic ion spin chains

Linear arrays of trapped and laser-cooled atomic ions are a versatile platform for studying strongly interacting many-body quantum systems. Effective spins are encoded in long-lived electronic levels of each ion and made to interact through laser-mediated optical dipole forces. The advantages of experiments with cold trapped ions, including high spatio-temporal resolution, decoupling from the external environment and control over the system Hamiltonian, are used to measure quantum effects not always accessible in natural condensed matter samples. In this review, we highlight recent work using trapped ions to explore a variety of non-ergodic phenomena in long-range interacting spin models, effects that are heralded by the memory of out-of-equilibrium initial conditions. We observe long-lived memory in static magnetizations for quenched many-body localization and prethermalization, while memory is preserved in the periodic oscillations of a driven discrete time crystal state.This article is part of the themed issue 'Breakdown of ergodicity in quantum systems: from solids to synthetic matter'.

Overproduction and purification of the luxR gene product: Transcriptional activator of the Vibrio fischeri luminescence system

Expression of Vibrio fischeri luminescence genes requires an inducer, termed autoinducer, and a positive regulatory element, the luxR gene product. A plasmid containing luxR under control of a tac promoter was engineered to overproduce this gene product. The overproduced luxR gene product was active in vivo, and its apparent monomeric molecular weight was indistinguishable from that of the protein encoded by luxR under control of its own promoter (M(r) 27,000). The new tac-luxR construct directed the synthesis of large quantities of the luxR gene product in induced Escherichia coli cells lacking other lux genes. In the presence of the other lux genes, overexpression of the tac-luxR construct was not detected. The overproduced luxR gene product, which formed cytoplasmic inclusion bodies, was purified and used in subsequent studies. Nonequilibrium pH gradient electrophoresis indicated that the protein was basic, and the amino-terminal 15 amino acids were sequenced. DNA-binding activity was detected by membrane filter binding assays; under the conditions used, the binding was not lux DNA-specific. Binding of tritium-labeled autoinducer to the luxR gene product was not detected, and autoinducer enhancement of the binding of the luxR gene product to DNA could not be detected reproducibly.

Evolution of sensory complexity recorded in a myxobacterial genome

Myxobacteria are single-celled, but social, eubacterial predators. Upon starvation they build multicellular fruiting bodies using a developmental program that progressively changes the pattern of cell movement and the repertoire of genes expressed. Development terminates with spore differentiation and is coordinated by both diffusible and cell-bound signals. The growth and development of Myxococcus xanthus is regulated by the integration of multiple signals from outside the cells with physiological signals from within. A collection of M. xanthus cells behaves, in many respects, like a multicellular organism. For these reasons M. xanthus offers unparalleled access to a regulatory network that controls development and that organizes cell movement on surfaces. The genome of M. xanthus is large (9.14 Mb), considerably larger than the other sequenced delta-proteobacteria. We suggest that gene duplication and divergence were major contributors to genomic expansion from its progenitor. More than 1,500 duplications specific to the myxobacterial lineage were identified, representing >15% of the total genes. Genes were not duplicated at random; rather, genes for cell-cell signaling, small molecule sensing, and integrative transcription control were amplified selectively. Families of genes encoding the production of secondary metabolites are overrepresented in the genome but may have been received by horizontal gene transfer and are likely to be important for predation.

Biofilm formation as microbial development

Biofilms can be defined as communities of microorganisms attached to a surface. It is clear that microorganisms undergo profound changes during their transition from planktonic (free-swimming) organisms to cells that are part of a complex, surface-attached community. These changes are reflected in the new phenotypic characteristics developed by biofilm bacteria and occur in response to a variety of environmental signals. Recent genetic and molecular approaches used to study bacterial and fungal biofilms have identified genes and regulatory circuits important for initial cell-surface interactions, biofilm maturation, and the return of biofilm microorganisms to a planktonic mode of growth. Studies to date suggest that the planktonic-biofilm transition is a complex and highly regulated process. The results reviewed in this article indicate that the formation of biofilms serves as a new model system for the study of microbial development.

The Myxococcus xanthus wbgB gene encodes a glycosyltransferase homologue required for lipopolysaccharide O-antigen biosynthesis

Myxococcus xanthus is a gram-negative soil bacterium that initiates a complex developmental program in response to starvation. A transposon insertion (Tn5-lac omega109) mutant with developmental deficiencies was isolated and characterized in this study. A strain containing this insertion mutation in an otherwise wild-type background showed delayed developmental aggregation for about 12 h and sporulated at 1-2% of the wild-type level. Tn5-lac omega109 was found to have disrupted the M. xanthus wbgB gene, which is located 2.1 kb downstream of the M. xanthus lipopolysacharide (LPS) O-antigen biosynthesis genes wzm wzt wbgA. The deduced polypeptide sequence of WbgB shares significant similarity with bacterial glycosyltransferases including M. xanthus WbgA. The wbgB::Tn5-lac omega109 mutant was found to be defective in LPS O-antigen synthesis by immunochemical analysis. Further mutational analysis indicated that the defects of the wbgB::Tn5-lac omega109 mutant were not the result of polar effects on downstream genes. Various motility assays demonstrated that the Tn5-lac omega109 mutation affected both social (S) and adventurous (A) gliding motility of M. xanthus cells. The pleiotrophic effects of wbgB mutations indicate the importance of LPS O-antigen biosynthesis for various cellular functions in M. xanthus.

Myxococcus xanthus dif genes are required for biogenesis of cell surface fibrils essential for social gliding motility

Myxococcus xanthus social (S) gliding motility has been previously reported by us to require the chemotaxis homologues encoded by the dif genes. In addition, two cell surface structures, type IV pili and extracellular matrix fibrils, are also critical to M. xanthus S motility. We have demonstrated here that M. xanthus dif genes are required for the biogenesis of fibrils but not for that of type IV pili. Furthermore, the developmental defects of dif mutants can be partially rescued by the addition of isolated fibril materials. Along with the chemotaxis genes of various swarming bacteria and the pilGHIJ genes of the twitching bacterium Pseudomonas aeruginosa, the M. xanthus dif genes belong to a unique class of bacterial chemotaxis genes or homologues implicated in the biogenesis of structures required for bacterial surface locomotion. Genetic studies indicate that the dif genes are linked to the M. xanthus dsp region, a locus known to be crucial for M. xanthus fibril biogenesis and S gliding.

Identification and characterization of genes required for early Myxococcus xanthus developmental gene expression

Starvation and cell density regulate the developmental expression of Myxococcus xanthus gene 4521. Three classes of mutants allow expression of this developmental gene during growth on nutrient agar, such that colonies of strains containing a Tn5 lac Omega4521 fusion are Lac(+). One class of these mutants inactivates SasN, a negative regulator of 4521 expression; another class activates SasS, a sensor kinase-positive regulator of 4521 expression; and a third class blocks lipopolysaccharide (LPS) O-antigen biosynthesis. To identify additional positive regulators of 4521 expression, 11 Lac(-) TnV. AS transposon insertion mutants were isolated from a screen of 18,000 Lac(+) LPS O-antigen mutants containing Tn5 lac Omega4521 (Tc(r)). Ten mutations identified genes that could encode positive regulators of 4521 developmental expression based on their ability to abolish 4521 expression during development in the absence of LPS O antigen and in an otherwise wild-type background. Eight of these mutations mapped to the sasB locus, which encodes the known 4521 regulators SasS and SasN. One mapped to sasS, whereas seven identified new genes. Three mutations mapped to a gene encoding an NtrC-like response regulator homologue, designated sasR, and four others mapped to a gene designated sasP. One mutation, designated ssp10, specifically suppressed the LPS O-antigen defect; the ssp10 mutation had no effect on 4521 expression in an otherwise wild-type background but reduced 4521 developmental expression in the absence of LPS O antigen to a level close to that of the parent strain. All of the mutations except those in sasP conferred defects during growth and development. These data indicate that a number of elements are required for 4521 developmental expression and that most of these are necessary for normal growth and fruiting body development.

Myxococcus xanthus sasN encodes a regulator that prevents developmental gene expression during growth

Myxococcus xanthus multicellular fruiting body development is initiated by nutrient limitation at high cell density. Five clustered point mutations (sasB5, -14, -15, -16, and -17) can bypass the starvation and high-cell-density requirements for expression of the 4521 developmental reporter gene. These mutants express 4521 at high levels during growth and development in an asgB background, which is defective in generation of the cell density signal, A signal. A 1.3-kb region of the sasB locus cloned from the wild-type chromosome restored the SasB+ phenotype to the five mutants. DNA sequence analysis of the 1.3-kb region predicted an open reading frame, designated SasN. The N terminus of SasN appears to contain a strongly hydrophobic region and a leucine zipper motif. SasN showed no significant sequence similarities to known proteins. A strain containing a newly constructed sasN-null mutation and Omega4521 Tn5lac in an otherwise wild-type background expressed 4521 at a high level during growth and development. A similar sasN-null mutant formed abnormal fruiting bodies and sporulated at about 10% the level of wild type. These data indicate that the wild-type sasN gene product is necessary for normal M. xanthus fruiting body development and functions as a critical regulator that prevents 4521 expression during growth.

A new set of chemotaxis homologues is essential for Myxococcus xanthus social motility

Myxococcus xanthus cells aggregate and develop into multicellular fruiting bodies in response to starvation. A new M. xanthus locus, designated diffor defective in fruiting, was identified by the characterization of a mutant defective in fruiting body formation. Molecular cloning, DNA sequencing and sequence analysis indicate that the dif locus encodes a new set of chemotaxis homologues of the bacterial chemotaxis proteins MCPs (methyl-accepting chemotaxis proteins), CheW, CheY and CheA. The dif genes are distinct genetically and functionally from the previously identified M. xanthus frz chemotaxis genes, suggesting that multiple chemotaxis-like systems are required for the developmental process of M. xanthus fruiting body formation. Genetic analysis and phenotypical characterization indicate that the M. xanthus dif locus is required for social (S) motility. This is the first report of a M. xanthus chemotaxis-like signal transduction pathway that could regulate or co-ordinate the movement of M. xanthus cells to bring about S motility.

The Myxococcus xanthus lipopolysaccharide O-antigen is required for social motility and multicellular development

The gliding bacterium Myxococcus xanthus aggregates to form spore-filled fruiting bodies when nutrients are limiting. Defective fruiting-body formation and sporulation result from mutations in the sasA locus, which encodes the wzm wzt wbgA (formerly rfbABC) lipopolysaccharide (LPS) O-antigen biosynthesis genes. Mutants carrying these same sasA mutations are defective in social motility and form small glossy colonies. We report here that the developmental and motility phenotypes of four mutants each containing different Tn5 insertions in LPS O-antigen biosynthesis genes are similar to those of the original sasA locus mutants. All of the LPS O-antigen mutants tested exhibited defective developmental aggregation and sporulated at only 0.02-15% of the wild-type level. In addition, all of the LPS O-antigen mutants were determined by genetic analyses to be wild type for adventurous motility and defective in social motility, indicating that the LPS O-antigen is necessary for normal development and social motility. The two previously identified cell-surface components required for social motility, type IV pili and the protein-associated polysaccharide material termed fibrils, were detected on the surfaces of all of the LPS O-antigen mutants. This indicates that LPS O-antigen is a third cell-surface component required for social motility.

Myxococcus xanthus sasS encodes a sensor histidine kinase required for early developmental gene expression

Initiation of Myxococcus xanthus multicellular development requires integration of information concerning the cells' nutrient status and density. A gain-of-function mutation, sasB7, that bypasses both the starvation and high cell density requirements for developmental expression of the 4521 reporter gene, maps to the sasS gene. The wild-type sasS gene was cloned and sequenced. This gene is predicted to encode a sensor histidine protein kinase that appears to be a key element in the transduction of starvation and cell density inputs. The sasS null mutants express 4521 at a basal level, form defective fruiting bodies, and exhibit reduced sporulation efficiencies. These data indicate that the wild-type sasS gene product functions as a positive regulator of 4521 expression and participates in M. xanthus development. The N terminus of SasS is predicted to contain two transmembrane domains that would locate the protein to the cytoplasmic membrane. The sasB7 mutation, an E139K missense mutation, maps to the predicted N-terminal periplasmic region. The C terminus of SasS contains all of the conserved residues typical of the sensor histidine protein kinases. SasS is predicted to be the sensor protein in a two-component system that integrates information required for M. xanthus developmental gene expression.

The Myxococcus xanthus developmentally expressed asgB-dependent genes can be targets of the A signal-generating or A signal-responding pathway

Functional Myxococcus xanthus A signal-generating and A signal-responding pathways are required for the progression through early multicellular development. To identify genes responsive to these pathways, the expression of eight early developmental genes was analyzed. This examination identified one gene as a target of the A signal-generating pathway and four genes as targets of the A signal-responding pathway.

A Myxococcus xanthus cell density-sensing system required for multicellular development

Progression through early Myxococcus xanthus multicellular fruiting body development requires the generation of and response to extracellular A signal. Extracellular A signal is a specific set of amino acids at an extracellular concentration greater than 10 muM. It functions as a cell density signal during starvation that allows the cells to sense that a minimal cell density has been reached and development can proceed. The generation of extracellular A signal requires the products of three asg genes. They have recently been identified as AsgA, a fused two-component histidine protein kinase and response regulator; AsgB, a putative DNA-binding protein; and AsgC, the M, xanthus major sigma factor. Other elements of the A signaling pathway map to the sasB locus and appear to be A signal transducers. These elements are regulators of the earliest A signal-dependent gene, whose promoter is a member of the sigma-54 family. Continued study of the A signaling pathway is expected to identify additional components of this network required for the complex behavioural response of fruiting body formation.

The Myxococcus xanthus rfbABC operon encodes an ATP-binding cassette transporter homolog required for O-antigen biosynthesis and multicellular development

A wild-type sasA locus is critical for Myxococcus xanthus multicellular development. Mutations in the sasA locus cause defective fruiting body formation, reduce sporulation, and restore developmental expression of the early A-signal-dependent gene 4521 in the absence of A signal. The wild-type sasA locus has been located on a 14-kb cloned fragment of the M. xanthus chromosome. The nucleotide sequence of a 7-kb region containing the complete sasA locus was determined. Three open reading frames encoded by the genes, designated rfbA, B and C were identified. The deduced amino acid sequences of rfbA and rfbB show identity to the integral membrane domains and ATPase domains, respectively, of the ATP-binding cassette (ABC) transporter family. The highest identities are to a set of predicted ABC transporters required for the biosynthesis of lipopolysaccharide O-antigen in certain gram-negative bacteria. The rfbC gene encodes a predicted protein of 1,276 amino acids. This predicted protein contains a region of 358 amino acids that is 33.8% identical to the Yersinia enterocolitica O3 rfbH gene product, which is also required for O-antigen biosynthesis. Immunoblot analysis revealed that the sasA1 mutant, which was found to encode a nonsense codon in the beginning of rfbA, produced less O-antigen than sasA+ strains. These data indicate that the sasA locus is required for the biosynthesis of O-antigen and, when mutated, results in A-signal-independent expression of 4521.

Identification of the minimum regulatory region of a Myxococcus xanthus A-signal-dependent developmental gene

Developmental expression of the Myxococcus xanthus gene 4521 requires extracellular A-signal. This signal is generated in response to nutrient limitation and functions in cell density sensing. To identify the upstream limit of the minimum region required in vivo for A-signal-dependent 4521 expression, a 5' deletion analysis of the 4521 regulatory region was performed. A new vector, pHBK280, was designed to facilitate this analysis. This vector creates tandem copies of the 4521 gene in the M. xanthus chromosome, such that the regulatory region to be tested is upstream of a single copy of the lacZ reporter gene. The 5' deletion analysis revealed that at most, 146 bp of DNA upstream of the transcription start site (TSS) was required for full developmental expression of 4521. Basal expression levels were observed with constructions containing 90 bp of DNA upstream of the TSS. In vitro gel retardation assays revealed that DNA fragments with 5' ends of 146 and 125 bp upstream of the TSS and a common 3' end of +24 bp were retarded in their mobility after incubation with all of the M. xanthus developmental crude cell extracts tested. In contrast, a fragment starting at 90 bp upstream of the TSS and ending at +24 bp was not retarded in its mobility after incubation with the same cell extracts. These in vivo and in vitro data suggest that cis-acting elements located between 146 and 90 bp upstream of the TSS serve as binding sites for one or more trans-acting regulatory factors required for 4521 developmental expression.

Life events, social support, and immune response in elderly individuals

One hundred ninety-two elderly men and women were investigated to determine the effects of recent life events, psychological adjustment, and social support on lymphocyte count, controlling for nutritional status, age, education, income, and the presence of lymphocyte-altering drugs. Effects of specific recent life events were found. For elderly males, recent sexual dysfunction lowers lymphocyte count, while psychological adjustment and percentage kin in the intimate network elevates it. For elderly females, the experience of either family or legal problems elevates lymphocyte count as does frequent interaction with members of the intimate network. These results suggest that life events have very different effects on elderly men and women's immune systems. Social support has direct but mediating effects on lymphocyte count for both genders.

Cell-cell interactions that direct fruiting body development in Myxococcus xanthus

The soil bacterium, Myxococcus xanthus initiates a developmental program when nutrients are limited. This results in the formation of a multicellular fruiting body structure filled with differentiated, environmentally resistant spores. At least four cell-cell signals, cell motility, and aggregation functions are required for the completion of fruiting body formation.

Suppressors that permit A-signal-independent developmental gene expression in Myxococcus xanthus

Progression through the early stages of Myxococcus xanthus fruiting body development requires the cell-to-cell transmission of soluble material called A signal. During these early stages, expression from the gene identified by Tn5 lac insertion omega 4521 increases. A DNA probe of the omega 4521 gene was constructed. Use of this probe showed that accumulation of mRNA corresponding to the omega 4521 gene depends upon A signal. A-signal-deficient (asg) mutants fail to accumulate this RNA, and the external addition of A signal restores accumulation. To identify links between A signal and its responsive gene, omega 4521, suppressors of an asg mutation were generated. All of the suppressor alleles restored lacZ expression from omega 4521 in the absence of A signal, and they were demonstrated to be neither reversions of the asgB mutation nor mutations in the promoter of omega 4521. Fifteen suppressor mutations map to two loci, sasA and sasB (for suppressor of asg). sasA and sasB mutants differ phenotypically during growth and development. Mid-logarithmic-phase sasA asgB double mutants, like sas+ asg+ strains, express low levels of lacZ, whereas sasB asgB double mutants express high levels. sasA asg+ mutants form abnormal colonies, are less cohesive than wild type, and are defective in fruiting body formation and sporulation. In contrast, sasB asg+ mutants form normal colonies, are as cohesive as wild type, and appear to develop normally. The characteristics of sasA suppressors implicate the sasA+ product as a negative regulator in the A-signal-dependent regulation of omega 4521.

Social psychology of the immune system: a conceptual framework and review of the literature

The literature on psychosocial factors affecting the immune system is reviewed. The literature is summarized in terms of a provisional model accounting for immunosuppression in terms of four mutually influential explanatory constructs (dysphoric responses; immunosuppressive behaviors; adverse life experiences; and vulnerability) and the relationships among the diverse manifestations of the constructs. The literature and the summary provisional model point to directions for future research that should establish the intervening role of immunosuppression in the relationships between psychosocial factors and the disease process.

Methodological problems in the study of psychosocial influences on the AIDS process

Recent psychosocial research on the onset and course of AIDS is reviewed toward the goal of identifying major methodological problems in carrying out such research. The problems are identified as related to guiding theoretical statements, sampling plans, validity of measurement models, and analytic strategies. Increased understanding of the onset and course of AIDS will depend on the speed and effectiveness with which the methodological problems are addressed.

Explaining adolescent drug use: an elaboration strategy for structural equations modeling

We report a series of analyses designed to estimate increasingly elaborated theoretical models that explain adolescent drug use. Each of the successive elaborations adds a theoretical construct to the explanatory model in order to increase our understanding of drug use by specifying in greater detail the nature of the structural relationships among the latent variables. The more detailed specification is accomplished by 1) specifying new direct effects that increase explained variance in drug use, 2) decomposing direct effects through the interpolation of hypothesized intervening variables, 3) specifying antecedents of variables that modify their direct effects, and 4) exposing suppressor effects. Where indicated, we evaluate alternative explanations of the observed relationships. We do this by controlling for common antecedent effects to reduce spuriousness or by examining different specifications of causal linkages among the explanatory constructs.

Complement activation during systemic lupus erythematosus. C3a and C5a anaphylatoxins circulate during exacerbations of disease

To determine whether activated complement components appear in the circulation of patients with systemic lupus erythematosus (SLE), we measured C5a and C3a by radioimmunoassay. Mean C5a concentration in the plasma of acutely ill SLE patients was 46.0 ng/ml, compared with 17.1 ng/ml in normal controls (P less than 0.01). Mean C3a concentration in patients with severe disease was 526 ng/ml, compared with 134 ng/ml in controls (P less than 0.01). In patients with moderately active SLE, the mean C3a concentration, but not the mean C5a concentration, was also elevated. In addition, C3a was elevated in 15 or 21 patients with active SLE, whereas low levels of C3 or C4 were noted in only 7 of these 21 patients. We conclude that the measurement of complement-derived anaphylatoxins may be useful in the management of patients with SLE. In addition, we suggest that these circulating mediators may contribute to the pathogenesis of vascular injury in patients with the disease.

Self-derogation and adjustment in the community: a longitudinal study of psychiatric patients

The authors assessed the symptoms and role performance of a group of psychiatric inpatients 1 year after their discharge to determine their level of adjustment in the community. Level of self-derogation at the time of discharge was consistently found to predict the level of adjustment. The occurrence of stressful life events was also predictive of symptoms but was not found to be significantly related to role performance. The chronicity of the disease was unrelated to adjustment. The change in self-derogation level and its ability to predict community adjustment is interpreted in terms of reestablishing the patient's belief in his or her own worth and efficacy.

Crisis treatment in a day hospital. Impact on medical care-seeking

The cost-effectiveness of a day hospital program is documented by examining the utilization of medical and psychiatric services before and after a time-limited following crisis-presentations. Patients in crisis have been shown to have increased need for services following a crisis. In contrast, medical-care events decreased for the population treated in the day hospital. The results, with respect to reduction of medical care were greatest for those patients judged to have benefited from the psychiatric interventions.

Diffusion of autoinducer is involved in regulation of the Vibrio fischeri luminescence system

The enzymes for luminescence in Vibrio fischeri are induced by the accumulation of a species-specific metabolite (autoinducer) in the culture medium. Tritium-labeled autoinducer was used to study the mechanism of autoinduction. When 3H-autoinducer was added to suspensions of V. fischeri or Escherichia coli, cellular concentrations equaled external concentrations. For V. fischeri, equilibration of 3H-autoinducer was rapid (within 20 s), and greater than 90% of the cellular tritium remained in unmodified autoinducer. When V. fischeri or E. coli cells containing 3H-autoinducer were transferred to autoinducer-free buffer, 85 to 99.5% of the radiotracer escaped from the cells, depending on the strain. Concentrations of autoinducer as low as 10 nM, which is equivalent to 1 or 2 molecules per cell, were sufficient for induction, and the maximal response to autoinducer occurred at about 200 nM. If external autoinducer concentrations were decreased to below 10 nM after induction had commenced, the induction response did not continue. Based on this study, a model for autoinduction is described wherein autoinducer association with cells is by simple diffusion and binding of autoinducer to its active site is reversible.

Generation of C5-derived peptides and other immune reactants in the sera of patients with systemic lupus erythematosus

Activated complement components and immune complexes cause neutrophil aggregation in vitro and in vivo. We have previously demonstrated that sera of patients with active systemic lupus erythematosus (SLE) provoke the aggregation of normal neutrophils in vitro. In this study the serum or plasma of 4 such patients was fractionated on Sephadex G-75. In 3 patients neutrophil aggregating activity (NAA) was detectable in fractions which coeluted with reference C5-derived peptides (estimated molecular radius of 17,000). The activity of these fractions was inhibitable by antibodies to human C5. All patients also had activity that coeluted with reference immune complexes. In addition, material of apparent molecular radius under 12,000 that contributed to the neutrophil aggregating activity of SLE sera was detected. In separate experiments increased levels of C5a desarg were demonstrated during active disease by means of radioimmunoassay. These findings suggest that multiple neutrophil aggregants circulate during the course of active SLE. The formation of intravascular leukoaggregates may contribute to endothelial injury in this disease.

Effects of non-steroidal anti-inflammatory agents on human neutrophil functions in vitro and in vivo

Human blood neutrophils exposed to appropriate stimuli aggregate, degranulate and generate superoxide anion (O2-). These responses are anteceded by mobilization of membrane-associated calcium, monitored as a decrease in fluorescence of cells preloaded with chlortetracycline (CTC). We studied the effects, both in vitro and in vivo, of non-steroidal anti-inflammatory agents (aspirin, indomethacin, ibuprofen and piroxicam) on these neutrophil responses to three stimuli: a chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (FMLP); a tumor promotor, phorbol myristate acetate (PMA); and a lectin, concanavalin A (Con A). The effects of these drugs were compared with those of two polyenoic inhibitors of arachidonate metabolism: eicosatrienoic acid (ETI) and eicosatetraynoic acid (ETYA). The pattern of inhibition of neutrophil functions varied both with inhibitor and the nature of the stimulus. Thus, aspirin, piroxicam, ETYA and ETI inhibited neutrophil aggregation, degranulation, and O2- generation in response to FMLP, whereas ibuprofen inhibited only aggregation and degranulation and indomethacin only inhibited aggregation. None of the agents inhibited aggregation or degranulation induced by PMA or Con A: only piroxicam inhibited O2- generation in response to PMA or Con A. ETI and ibuprofen inhibited decrements of CTC fluorescence induced by FMLP, but whereas ETI inhibited the CTC response to PMA or Con A, ibuprofen was without effect. The agents had varying effects on binding of the stimulus [( 3H]FMLP, [3H]Con A), but these did not correlate with neutrophil responses to the ligands. Neutrophils from subjects taking therapeutic doses of ibuprofen, indomethacin, or piroxicam showed profiles of inhibited responses to FMLP similar to those observed with these agents in vitro. These data suggest that, although non-steroidal anti-inflammatory agents may inhibit discrete neutrophil functions both in vitro and in vivo, their effects do not duplicate those of polyenoic inhibitors of arachidonate metabolism. Moreover, since the susceptibility of neutrophils differed not only with respect to each inhibitor, but also to the stimulus, it is unlikely that all neutrophil responses are necessarily linked by a common pathway that is blocked by inhibitors of arachidonic acid metabolism.

Effects of diagnosis and treatment history on relapse of psychiatric patients

Of 400 patients followed up for 1 year after release from the hospital, 34% were readmitted during that year. For schizophrenic patients the readmission rate was 49%, and for nonschizophrenic patients it was 21%. Rate of rehospitalization was positively related to number of prior hospitalizations, cumulative months of prior hospitalization, and duration of illness, but the relationship varied between the schizophrenic and nonschizophrenic groups. In contrast to the findings of Linn and associates, in this study prior hospitalization of nonschizophrenic patients markedly increased the likelihood of rehospitalization.

The roles of degranulation and superoxide anion generation in neutrophil aggregation

Human neutrophils when exposed to appropriate stimuli aggregate, generate O(2) and secrete lysosomal constituents. To determine whether a causal relationship may exist between these responses neutrophils were exposed to either N-formyl-methionyl-leucyl-phenylalanine, phorbol myristate acetate, or the two calcium ionophores, A23187 and prostaglandin Bx. Each agent elicited all of the above responses. The concentrations required to elicit the aggregation of 30 . 10(6) neutrophils/ml were comparable to that required for O(2) generation or lysozyme release. In a series of experiments designed to dissociate these responses, cells were suspended in a concentration too dilute (3 . 10(6) neutrophils/ml) to permit aggregation to occur. O(2) generation and lysozyme release was measurable and varied in a dose-dependent fashion to the concentration of stimulus. In a second series of experiments, neutrophils were treated with 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid to inhibit degranulation without affecting O(2) generation. Aggregation was inhibited in a parallel fashion with lysozyme release. When detectable O(2) was removed from the medium by superoxide dismutase and catalase, aggregation and lysozyme release unaffected showing that aggregation can not be due to the presence of O(2) or its products in the extracellular medium. Neither aggregation of resting cells nor augmentation of fMet-Leu-Phe-induced aggregation was observed when cells were exposed to either supernatants of degranulated neutrophils or constituents of specific granules (lysozyme, lactoferrin). Kinetic analysis showed that in the absence of cytochalasin B degranulation preceded aggregation, while in its presence aggregation preceded degranulation.

Ceruloplasmin: an acute phase reactant that scavenges oxygen-derived free radicals

Superoxide anion radicals have been implicated recently as mediators of inflammation and tissue injury. Protection from superoxide anion radicals is provided primarily by a copper-containing, intracellular enzyme (superoxide dismutase) (SOD) that catalyzes the dismutation of superoxide to hydrogen peroxide and oxygen. We have found that the action of cytoplasmic SOD to scavenge superoxide and thereby to inhibit superoxide-mediated reactions can be mimicked by the copper-containing plasma protein and acute-phase reactant, ceruloplasmin. Ceruloplasmin, at concentrations present in normal plasma, inhibited reduction of both cytochrome c and nitroblue tetrazolium (NBT) mediated by the aerobic action of xanthine oxidase on hypoxanthine (a superoxide-generating system). Ceruloplasmin neither inhibited formation of uric acid by xanthine oxidase nor accelerated autooxidation of cytochrome c. Furthermore, in an experimental system in which contact between ceruloplasmin and indicator was prevented by a relatively impermeable lipid membrane barrier, ceruloplasmin inhibited reduction of NBT trapped within liposomes exposed to xanthine oxidase and hypoxanthine. Ceruloplasmin also inhibited reduction of cytochrome c and NBT mediated by the aerobic action of xanthine oxidase on acetaldehyde (another superoxide-generating system) and mimicked the activity of purified human erythrocyte SOD by inhibiting photoreduction of NBT and by accelerating aerobic photooxidation of dianisidine. Ceruloplasmin could be separated from purified human erythrocyte SOD by electrophoresis on alkaline 12% polyacrylamide gels and identified by its superoxide-scavenging activity. These results suggest that ceruloplasmin may function as a circulating scavenger of oxygen-derived free radicals.

Effect of high-dose methylprednisolone infusion on polymorphonuclear leukocyte function in patients with systemic lupus erythematosus

We have studied the effect of high-dose (1 gm) methylprednisolone infusion on polymorphonuclear leukocyte (PMN) function in 11 patients with active systemic lupus erythematosus (SLE). The only alteration of polymorphonuclear leukocyte function produced consistently by methylprednisolone was decreased adherence to plastic surfaces when tested 2 hours after infusion. This steroid-induced abnormality, however, was transient. Cells obtained from patients 24 hours after a single dose of drug exhibited normal adhesiveness. These results indicate that single, large doses of methylprednisolone do not produce long-lasting abnormalities of PMN function in patients with lupus.

Thromboxane generation by human peripheral blood polymorphonuclear leukocytes

Human peripheral blood polymorphonuclear leukocytes were stimulated to generate thromboxane B2 in a time- and concentration-dependent fashion upon exposure to serum-treated zymosan particles. Conversion by stimulated PMN of [14C] arachidonic acid to [14C]thromboxane B2 was confirmed by thin-layer radiochromatography, radio-gas chromatography, and mass spectrometry. Generation of thromboxane B2 was independent of platelet contamination and could be inhibited by the cyclooxygenase inhibitor, indomethacin. Cells rendered incapable of ingesting particles by treatment with cytochalasin B generated comparable amounts of thromboxane B2. These results suggest that human peripheral blood polymorphonuclear leukocytes synthesize thromboxanes in response to surface stimulation independently of phagocytosis.

Evidence of complement catabolism in acute pancreatitis

Active proteolytic enzymes are released into the gland parenchyma and surrounding tissues during episodes of acute pancreatitis. Since complement components are potential substrates for active proteases and may be the source of biologically active peptides capable of mediating tissue injury, we have examined sera obtained from 12 patients during 13 episodes of acute pancreatitis for evidence of complement catabolism. In 8 of 13 acute phase sera, there were decreased levels of CH50, C3, C4, or some combination thereof as well as degradation products of C3 (revealed by crossed immunoelectrophoresis). In convalescent sera, levels of complement components were normal or elevated. Measurements of alpha1-antitrypsin, alpha2-macroglobulin, and trypsin inhibitory capacity failed to reveal evidence of protease-antiprotease imbalance. These findings provide evidence of complement catabolism in acute pancreatitis and suggest the possibility that activated complement components may play a role in the pathogenesis of some systemic pathologic changes which occur in this disease.

Evidence that the superoxide-generating system of human leukocytes is associated with the cell surface

Superoxide anion (O-2-) generation by human peripheral blood polymorphonuclear leukocytes is enhanced when these cells encounter appropriate soluble or particulate stimuli. O-2- generation requires intact, viable cells and proceeds independently of phagocytosis. To investigate the possibility that the O-2--generating system is associated with the outer surface of the polymorphonuclear leukocyte plasma membrane, we have examined the effects upon O-2- production of p-diazobenzenesulfonic acid, a reagent which can react predominantly with proteins of the external cell membrane. When normal human polymorphonuclear leukocytes were preincubated with cytochalasin B (to minimize endocytosis) and then exposed to the surface-active lectin, concanavalin A, the cells were stimulated to generate O-2- in a concentration- and time-dependent fashion and selectively to discharge the granule-associated enzyme, lysozyme, into the surrounding medium. These responses, as well as cellular binding of [H] concanavalin A, could be blocked by alpha-methyl-D-mannoside. Brief treatment (less than 5 min at 4 degrees C) of the cells with p-diazobenzenesulfonic acid (1.0-5.0 mM) significantly interfered with concanavalin A-mediated O-2- generation but had no influence upon lysozyme release or upon binding of [3H] concanavalin A. The diazonium salt did not alter cell viability or the specific activity of the cytoplasmic enzyme, lactate dehydrogenase (inhibitable under conditions which allowed entry of this reagent into the cytosol). p-Diazobenzenesulfonic acid, therefore, very likely exerted its effects at the cell surface of the intact polymorphonuclear leukocyte, selectively inhibiting O-2- production (either directly or indirectly) without influencing another response to lectin-cell contact: release of lysozyme. These results support the possibility that a polymorphonuclear leukocyte ectoenzyme is responsible for O-2- production.

Independent effects of IgG and complement upon human polymorphonuclear leukocyte function

Particle ingestion by polymorphonuclear leukocytes (PMN) is promoted by cell surface recognition and binding of fragments of the third component of complement (C3) and Fc regions of certain immunoglobulin (IgG) molecules. In order to determine the influence of these specific ligandsurface membrane interactions upon other PMN functions, we have employed nonphagocytosable particles (serum-treated Sepharose beads) coated with fragments of C3 and/or IgG, and have investigated whether these provide a sufficient stimulus for the metabolic changes and degranulation that ordinarly accompany phagocytosis by PMN. Sepharose 4B activates complement in fresh normal serum and consequently is coated with fragments of C3 (confirmed by immunoelectrophoretic evidence of factor B and C3 conversion and by immunofluorescence). Adsorbed IgG could be removed from serum-treated Sepharose by boiling in 2 M NaCl without significantly influencing bound complement. We have found that normal human PMN recognize and adhere to Sepharose beads coated with fragments of C3 and consequently are stimulated to increase their oxidative metabolism (measured as superoxide anion generation). This PMN response occurred in the absence of IgG but could be amplified if this immunoglobulin was also present on the bead surfaces. Both adherence and metabolic stimulation could be blocked by treatment of the beads with F(ab)2 anti-C3. In contrast to metabolic stimulation, degranulation (selective extracellular release of lysosomal constituents) was observed only when PMN encountered both C3 fragments and IgG on the beads. This response could be blocked by treating beads with either F(ab)2 anti-C3 or F(ab)2 anti-IgG. These results indicate that cell surface stimulation of PMN is not an "all or none" phenomenon and that certain vital functions of these cells may be mediated or modulated independently by immunoglobulins and complement.

Prediction of chronicity in psychiatric patients

In order to determine the best combination of variables for predicting which patients would be released from state mental hospitals and which would be retained, the 1,500 patients examined in the course of a cross-sectional survey of the residental population of Texas state mental hospitals in 1966 were followed up in 1971. Eighteen variables were selected for discriminant analysis, comparing the patients nerver released from the hospital with those known to be current extrainstitutional residents. The stepwise program selected four variables: (1) length of prior stay; (2) relatives' attitudes toward release; (3) social adequacy; and (4) conceptual disorganization. Applying this model to the study groups, 79% were correctly classified with regard to their in hospitals/not in hospital status, suggesting that early identification of chronicity in future studies is feasible.

Dissociation of phagocytosis, metabolic stimulation and lysosomal enzyme release in human leukocytes

In this paper studies are reported concerning the relationship between particle binding to the plasma membrane of human polymorphonuclear leukocytes (PMN's), phagocytosis, generation of oxidative metabolites, and the release of lysosomal enzymes by these cells. Superoxide (O2-) generation by, and lysosomal enzyme release from, normal PMN's and cytochalasin B-treated cells were measured. We have found that neither phagocytosis nor lysosomal degranulation are prerequisites for enhanced O2- generation. Cytochalasin B-treated PMN's, incapable of ingesting particles but still able to bind particles to membrane receptors, generated enhanced amounts of O2- when treated with serum-treated zymosan (STZ), a C3b receptor stimulus, or with aggregated IgG (agg IgG), an Fc receptor stimulus. Moreover, the soluble stimulators complement component C5a, phorbol myristate acetate (PMA), and calcium ions in the presence of the ionophore A23187, also increased the O2- production of these cells. In all cases a time and dose-dependent stimulation was found of both the O2- generation and the lysosomal enzyme release, but there was no correlation between ability of any stimulus to provoke enzyme release and its ability to stimulate O2- generation. When PMN's were preincubated with 5 X 10(-4) M hydrocortisone-Na-succinate, lysosomal enzyme exocytosis with the immune reactants was inhibited 16-35%. Hydrocortisone also inhibited O2- generation, except when STZ was used as the stimulus. Thus, in the case of stimulation of functional processes of PMN's via the C3b receptor, hydrocortisone inhibits membrane fusion without interfering with one of the early biochemical events (O2-production).